From 0ea59652fa4974e37c726a17403d05edb75142b3 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 11 Apr 2026 20:36:52 -0600 Subject: [PATCH 001/125] Add QEC simulator literature survey scaffold --- design/qec_sim_literature.md | 293 +++++++++++++++++++++++++++++++++++ 1 file changed, 293 insertions(+) create mode 100644 design/qec_sim_literature.md diff --git a/design/qec_sim_literature.md b/design/qec_sim_literature.md new file mode 100644 index 000000000..bfe99fbb7 --- /dev/null +++ b/design/qec_sim_literature.md @@ -0,0 +1,293 @@ +# QEC Simulator Literature Survey: Candidate Gaps in PECOS + +Status: draft / scaffold +Scope: quantum **simulators** (not decoders) useful for QEC research that PECOS does not currently implement or is not actively working on. + +## Current PECOS simulator coverage (for reference) + +| Family | PECOS impl | +|---|---| +| Stabilizer tableau (sparse/dense) | `SparseStab`, `DenseStab`, `GpuStab` (wgpu), `CuStabilizer`, `pecos-cppsparsestab` | +| State vector | `StateVec` (SoA/AoS), `CuStateVec`, Qulacs, QuEST | +| Density matrix | `DensityMatrix`, `CuDensityMat`, QuestDensityMatrix | +| Clifford + T / CH-form | `CliffordRz` | +| Stabilizer + tensor network / magic states | `STN` (stabilizer tableau + MPS), `MAST` (magic-state injection + deferred ancilla projection, Clifford disentangling) -- active on branch/worktree `study/tensor-network-clifford-rz` | +| Tensor network | `CuTensorNet` | +| Pauli propagation | `PauliProp` | +| Graph state | `GraphStateSim` | +| ZX calculus | `pecos-zx` (exp) | +| Composable noise | `pecos-neo` (exp) | +| **Detector Error Model (Stim-compat)** | `pecos-qec::fault_tolerance::dem_builder` -- `DemBuilder` + `DemSamplerBuilder` (SoA batch sampler) | +| **Stabilizer-rank / sum-over-Cliffords** | `CliffordRz` via CH-form sum decomposition (Bravyi 1808.00128) | + +## Out-of-scope (already covered or actively developed) + +Do **not** propose these as gaps: + +- **Stim-style DEM generation and sampling** -- `pecos-qec::fault_tolerance::dem_builder` (`DemBuilder`, `DemSamplerBuilder`). +- **Stabilizer-rank / sum-over-Cliffords simulation** -- `CliffordRz` (CH-form, Bravyi 1808.00128). +- **Stabilizer + tensor-network hybrids / magic-state injection via MPS** -- `STN` and `MAST` on branch/worktree `study/tensor-network-clifford-rz`. +- **Composable gate-level noise channels** -- `pecos-neo` (depolarizing, measurement, idle, crosstalk, leakage, custom). + +Sections below that originally proposed any of these have been revised to focus on *refinements* or *wrapper backends* rather than net-new simulators. + +## Candidate gap families + +Each entry below is a simulation family that appears **not covered** by the above. TODOs mark items still to validate. + +--- + +### 1. (REVISED) Alternatives to PECOS's existing DEM sampler + +**Correction.** PECOS **already has** a Stim-compatible DEM generator and fast batch sampler at `crates/pecos-qec/src/fault_tolerance/dem_builder/`: `DemBuilder` (per-qubit fault model, 15 Pauli combos for 2Q gates, Stim-format output, hyperedge decomposition for MWPM) and `DemSamplerBuilder` (SoA / CSR / bit-packed u64 / rayon batch sampling). + +**So the real question is:** what *simulator backends* could feed or complement the existing DemSampler? + +The DemSampler today operates on a `DagFaultInfluenceMap` produced by circuit-level *fault propagation analysis* (not a full quantum sim). That is deliberate and fast, but it assumes Pauli/depolarizing-tractable noise. Gaps worth a literature hunt: + +- **Stim as a cross-validation backend.** Wrap `stim.Circuit -> DEM` via PyO3/FFI so PECOS circuits can be round-tripped through Stim and diffed against PECOS's own DEM. Test harness already exists (`test_dem_sampler_vs_stim.py`). Worth formalizing as a first-class optional backend. +- **Coherent / non-Pauli noise -> effective DEM.** For circuits with rotations, coherent over-rotations, leakage, crosstalk, the Pauli-twirled DEM loses information. Candidates to compute an *approximate* DEM from a richer sim: + - Lindblad / trajectory sim (see #7 below) -> tomographic per-location Pauli channel -> feed into DemBuilder. + - Pauli-Lindblad learned models (see #9) -> sparse correlated error mechanisms as DEM hyperedges. + - Matchgate / FLO (see #2) where tractable, for exact coherent error rates on small gadgets. +- **Non-Clifford logical gadgets.** For T / magic-state circuits, the influence-map pipeline must handle non-Pauli effects. `CliffordRz` (CH-form sum) is a candidate backend for an "exact small-DEM" oracle used to validate approximations. + +**Seminal / anchor refs.** +- C. Gidney, *Stim: a fast stabilizer circuit simulator*, Quantum 5, 497 (2021). arXiv:2103.02202 +- Stim's DEM spec + Sinter sampling harness (docs). + +**Action items.** +- [ ] Survey how Stim, qec_lib, and qsim's circuit-level noise adapters handle non-Pauli noise lowering. +- [ ] Decide whether PECOS's DemBuilder gains a `from_channel(qubit_op, ...)` entry point that accepts PTM / Choi / Lindblad and lowers to Pauli rates. +- [ ] Evaluate PyO3 `stim` bridge as an optional cross-check backend. + +--- + +### 2. Matchgate / Free-fermion / Fermionic-linear-optics (FLO) simulators + +**What it is.** Efficient classical simulation of matchgate circuits (nearest-neighbor 2-qubit gates satisfying matchgate identities) via covariance-matrix evolution. Equivalent to non-interacting fermion dynamics. + +**Why QEC needs it.** Majorana / fermionic codes, certain LDPC constructions built from free-fermion layers, boundary-matching benchmarks, noise models where errors are Gaussian-fermionic. Also useful as a sanity-check oracle for small non-Clifford circuits that happen to be matchgate-reducible. + +**PECOS status.** Not present. + +**Seminal refs.** +- Valiant, *Quantum circuits that can be simulated classically in polynomial time*, SIAM J. Comput. 31 (2002). +- Knill, *Fermionic Linear Optics and Matchgates* (2001), arXiv:quant-ph/0108033. +- Terhal, DiVincenzo (2002), arXiv:quant-ph/0108010. +- Jozsa, Miyake, *Matchgates and classical simulation of quantum circuits*, Proc. R. Soc. A 464 (2008). + +**Existing OSS.** +- `Flo-simulator` (GitHub academic repo) -- matchgate + non-Gaussian gate simulator (Cudby-Strelchuk 2024, arXiv:2307.12702 / Quantum 2024). +- OpenFermion-FQE (fermionic quantum emulator; second-quantized, not matchgate-specialized but adjacent). +- No widely-used production library -- niche for PECOS. + +**Newer ref worth tracking.** +- Cudby, Strelchuk, *Improved simulation of quantum circuits dominated by free fermionic operations*, Quantum 8 (2024), DOI 10.22331/q-2024-12-04-1549. + +--- + +### 3. Decision-diagram simulators (QMDD / DDSIM) + +**What it is.** Represent state/operator as a reduced decision diagram (QMDD, TDD, LIMDD). Exponential compression on structured circuits, exact non-Clifford. + +**Why QEC needs it.** Exact verification of small logical gadgets (magic-state distillation circuits, small code blocks), cross-checking approximate sims, equivalence checking of compiled vs logical circuits. + +**PECOS status.** Not present. + +**Seminal refs.** +- Miller, Thornton, *QMDD: A Decision Diagram Structure for Reversible and Quantum Circuits* (2006). +- Zulehner, Wille, *Advanced Simulation of Quantum Computations*, IEEE TCAD (2019). +- Vinkhuijzen et al., *LIMDD: A Decision Diagram for Simulation of Quantum Computing Including Stabilizer States*, Quantum 7 (2023). + +**Existing OSS.** +- MQT DDSIM (Munich Quantum Toolkit) -- C++20/Python, actively maintained: https://github.com/munich-quantum-toolkit/ddsim +- LIMDD branch of DDSIM: https://github.com/munich-quantum-toolkit/ddsim/tree/limdd -- first LIMDD implementation, compactly represents stabilizer states *and* DD-friendly non-stabilizer states. +- Q-Sylvan (parallel DD package for quantum, Springer 2025). + +**Newer ref worth tracking.** +- Vinkhuijzen et al., *LIMDD*, Quantum 7 (2023) 1108. +- Tutorial: Quantum Inf. Process. (2025), https://doi.org/10.1007/s11128-025-04917-0. + +--- + +### 4. (REVISED) Stabilizer-rank / sparsification refinements to CliffordRz + +**Correction.** `CliffordRz` is a stabilizer-rank simulator -- it represents states as sum of CH-form stabilizer states and cites Bravyi et al. (arXiv:1808.00128). Each RZ doubles the term count; norm computation uses CH-form inner products. See `docs/concepts/clifford-rz-simulator.md`. + +**Open research directions** (things CliffordRz may not already cover): + +- **Sparsification / random stabilizer decomposition.** Bravyi-Smith-Smolin style *sampling* from the sum rather than carrying all 2^t terms -- runtime scales with *stabilizer extent* / *robustness of magic*, not 2^t. +- **Low-extent magic state decompositions.** Replace per-RZ doubling with structured multi-T decompositions (|T> Pauli-rotation IR -> lattice surgery ops + visualizer. +- PennyLane has a PBC compilation module. + +--- + +### 6. Bosonic / continuous-variable simulators (GKP, cat, binomial codes) + +**What it is.** Fock-truncated or phase-space (Wigner, Husimi) simulation of bosonic modes with Gaussian + non-Gaussian operations. + +**Why QEC needs it.** GKP codes, cat codes, binomial codes, dual-rail, concatenated bosonic-qubit codes. Increasingly central to neutral-atom / superconducting bosonic / photonic QEC. PECOS is qubit-only. + +**PECOS status.** Not present. + +**Seminal refs.** +- Gottesman, Kitaev, Preskill, *Encoding a qubit in an oscillator*, PRA 64 (2001). +- Mirrahimi et al., *Dynamically protected cat-qubits*, NJP 16 (2014). +- Michael et al., *New Class of Quantum Error-Correcting Codes for a Bosonic Mode*, PRX 6 (2016). + +**Existing OSS.** +- Bosonic Qiskit (C2QA / IBM-NQI) -- qumode + qubit hybrid circuits: https://github.com/C2QA/bosonic-qiskit +- Mr Mustard (Xanadu) -- differentiable Gaussian + Fock, phase-space <-> Fock bridge: https://github.com/XanaduAI/MrMustard +- Dynamiqs -- JAX-based GPU Lindblad / SME solvers; used by Alice & Bob for cat-qubit chips: https://github.com/dynamiqs/dynamiqs +- Strawberry Fields (Xanadu, photonic CV). +- `EQuS/bosonic` -- deprecated, now `jaxquantum.circuits` / `jaxquantum.codes` (2025-07-13). +- Piquasso (photonic QC platform, Quantum 2025). + +**Newer ref worth tracking.** +- *Bosonic Pauli+*: efficient simulation of concatenated GKP codes, arXiv:2402.09333. +- *Classical simulation of circuits with realistic odd-dimensional GKP states*, arXiv:2412.13136. +- *Fast simulation of bosonic qubits via Gaussian functions in phase space*, PRX Quantum 2 040315 (2021). +- *Universal gate set for GKP logical qubits*, Nat. Phys. (2025). + +--- + +### 7. Lindblad / master-equation + quantum-trajectory simulators + +**What it is.** Continuous-time evolution under Lindbladians, optionally unraveled as stochastic quantum trajectories (Monte Carlo wavefunction / quantum jumps). + +**Why QEC needs it.** Realistic noise: T1/T2, coherent errors, leakage, crosstalk, cross-resonance dynamics; non-Markovian extensions; studying Pauli-twirl approximation error; modeling syndrome extraction in the analog regime. + +**PECOS status.** `pecos-neo` has composable noise channels at the gate/Pauli level, but no continuous-time Lindblad or trajectory solver (TODO: verify). + +**Seminal refs.** +- Dalibard, Castin, Molmer (1992) [MCWF]. +- Plenio, Knight (1998) [review]. +- Modern: Johansson, Nation, Nori, *QuTiP* (2012/2013). + +**Existing OSS.** +- QuTiP (Python) -- reference implementation, `mesolve` / `mcsolve`. +- Dynamiqs (JAX, GPU-accelerated, differentiable) -- 30-60x speedup on dissipative cat CNOT: https://github.com/dynamiqs/dynamiqs +- QuantumToolbox.jl (Julia, QuTiP-like syntax, distributed + GPU): https://github.com/qutip/QuantumToolbox.jl -- arXiv:2504.21440. +- C3 (characterization / control / calibration framework). + +**Newer ref worth tracking.** +- Lambert et al., *QuantumToolbox.jl* (2025), arXiv:2504.21440. +- *Efficient Lindblad synthesis for noise model construction*, npj QI 11 (2025), arXiv:2502.03462 -- bridges Lindblad sims to Pauli-noise models (useful for feeding DEM pipelines). + +--- + +### 8. Fermion-native simulators (no Jordan-Wigner cost) + +**What it is.** Second-quantized fermion operators simulated directly (matrix-product-fermion states, Gaussian fermion + low-rank non-Gaussian, etc.) without qubit mapping overhead. + +**Why QEC needs it.** Fermionic codes (Majorana fermion code, Bravyi-Kitaev-style fermionic LDPC), QEC for fermionic simulation itself (fault-tolerant chemistry), tensor-network methods on fermionic Hilbert spaces. + +**PECOS status.** Not present. + +**Anchor refs.** +- Bravyi, Kitaev, *Fermionic Quantum Computation*, Ann. Phys. 298 (2002). +- Corboz, Vidal, *Fermionic multiscale entanglement renormalization ansatz* (2009). + +**Existing OSS.** OpenFermion (operator-level, not fast sim), ITensor fermionic MPS, TeNPy. + +--- + +### 9. Correlated / Pauli-Lindblad noise model simulators + +**What it is.** Circuit-level noise with correlated (multi-qubit) Pauli-Lindblad generators, learned from device tomography (IBM's PEC/PEA pipeline). Not pure iid depolarizing. + +**Why QEC needs it.** Accurate threshold / pseudo-threshold estimates on real hardware; studying impact of correlations on matching decoders; PEC-assisted QEC experiments. + +**PECOS status.** `pecos-neo` supports crosstalk/leakage channels (good start); unclear if Pauli-Lindblad learned models are a first-class input. TODO: verify with `pecos-neo` docs. + +**Seminal refs.** +- van den Berg, Minev, Kandala, Temme, *Probabilistic error cancellation with sparse Pauli-Lindblad models*, Nat. Phys. 19 (2023). arXiv:2201.09866. +- Cai et al., *Quantum error mitigation*, RMP (2023). + +**Newer refs worth tracking.** +- Chen et al., *Techniques for learning sparse Pauli-Lindblad noise models*, Quantum 8 (2024), DOI 10.22331/q-2024-12-10-1556. arXiv:2311.15408. +- *Efficient Lindblad synthesis for noise model construction*, npj QI (2025), arXiv:2502.03462. +- *Bayesian inference of general noise-model parameters from surface-code syndrome statistics*, arXiv:2406.08981 (couples learned noise -> DEM-style decoder input). + +--- + +### 10. Weak-simulation samplers via quasi-probability / negativity + +**What it is.** Sample measurement outcomes of near-Clifford circuits via quasi-probability decompositions (Wigner negativity, Howard-Campbell robustness of magic). Runtime scales with negativity/robustness, not 2^n. + +**Why QEC needs it.** Resource-theoretic analysis of magic injection, distillation cost lower bounds, benchmarking distillation protocols. + +**PECOS status.** Not present. + +**Anchor refs.** +- Pashayan, Wallman, Bartlett, *Estimating outcome probabilities of quantum circuits using quasiprobabilities*, PRL 115 (2015). +- Howard, Campbell, *Application of a Resource Theory for Magic States to Fault-Tolerant Quantum Computing*, PRL 118 (2017). + +--- + +### 11. Fusion-based / measurement-based photonic QEC sims + +**What it is.** Discrete-variable photonic FBQC / MBQC: cluster-state construction via fusion gates, loss + dephasing noise, percolation-threshold analysis. + +**Why QEC needs it.** PsiQuantum-style FBQC, measurement-based surface codes, photonic interfaces. PECOS `GraphStateSim` has the states but not the fusion/loss sim layer. + +**Anchor refs.** +- Bartolucci et al. (PsiQuantum), *Fusion-based quantum computation*, Nat. Commun. 14 (2023). +- Raussendorf, Harrington, Goyal, *A fault-tolerant one-way quantum computer*, Ann. Phys. 321 (2006). + +--- + +## Ranking (grug's revised first-cut opinion) + +Given PECOS already has DemSampler, CliffordRz, STN/MAST, pecos-neo: + +1. **Lindblad / trajectory backend** (#7) -- only honest way to study coherent / non-Pauli noise. Wraps nicely into DemBuilder via channel->Pauli-rate lowering (Efficient Lindblad synthesis, arXiv:2502.03462). Highest leverage. +2. **Bosonic / CV** (#6) -- bosonic codes are a major growth area; PECOS currently qubit-only. Biggest scope expansion. +3. **Stim cross-validation bridge for DemSampler** (revised #1) -- low effort, high value for regression testing. +4. **CliffordRz sparsification** (revised #4) -- confirmed absent, straightforward refinement of existing sim. +5. **Pauli-Lindblad correlated noise into DEM** (#9) -- IBM-style learned noise -> PECOS DEM pipeline. Good synergy with item 1. +6. **Pauli-based computation** (#5) -- matches FTQC resource accounting directly, good pairing with MAST. + +Rest (matchgate, decision diagrams, fermion-native, quasiprobability, fusion-based) are narrower or more research-y. + +## TODOs before formalizing + +- [x] Confirm `PauliProp` does not already extract DEMs -- correction: `pecos-qec::fault_tolerance::dem_builder` already does. +- [x] Audit CliffordRz for sparsification -- none present. +- [ ] Verify `pecos-neo` scope in detail (Pauli-Lindblad learned input format? continuous-time?). +- [ ] Check `STN/MAST` docs on `study/tensor-network-clifford-rz` for overlap with stabilizer-rank sampling (may already cover some of the CliffordRz refinements). +- [ ] Ask maintainer which roadmap items (if any) already claim Lindblad / bosonic / PBC. +- [ ] Add OSS licence notes per wrapper candidate (Dynamiqs: Apache-2.0? Bosonic Qiskit: Apache-2.0? Stim: Apache-2.0; confirm). From 1364efe567037c4b042eda69cafcd87ff1242ab7 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 11 Apr 2026 20:38:50 -0600 Subject: [PATCH 002/125] Add DemStabSim wrapper proposal and next-sim recommendation --- design/qec_sim_literature.md | 119 +++++++++++++++++++++++++++++++++++ 1 file changed, 119 insertions(+) diff --git a/design/qec_sim_literature.md b/design/qec_sim_literature.md index bfe99fbb7..06f2937e5 100644 --- a/design/qec_sim_literature.md +++ b/design/qec_sim_literature.md @@ -283,6 +283,125 @@ Given PECOS already has DemSampler, CliffordRz, STN/MAST, pecos-neo: Rest (matchgate, decision diagrams, fermion-native, quasiprobability, fusion-based) are narrower or more research-y. +--- + +## Proposal: DemSampler-backed "fast stabilizer + depolarizing" simulator + +**Goal.** Expose the existing DemSampler / fault-influence-map machinery as a **first-class simulator** alongside `SparseStab`, `CliffordRz`, `StateVec`, etc. Stim is inspiration only -- PECOS stays self-contained. + +**What it gives the user.** A drop-in sim for the most common QEC research workload: Clifford circuit + per-location depolarizing-family noise -> detector + observable + raw-measurement samples at Stim-competitive speeds. Reuses every piece PECOS already has (`DagFaultAnalyzer`, `DemBuilder`, `DemSamplerBuilder`, `NoisySampler`) instead of adding a new algorithm. + +### Why this is a real simulator, not just sugar + +Stim's core algorithm *is* "Pauli-frame propagation through a Clifford circuit with per-location Pauli noise, aggregated into detector/observable signatures, then sampled shot-wise". That is exactly what PECOS's fault-influence + DemSampler pipeline does today. Wrapping it behind a simulator-shaped API makes the equivalence visible and reusable. Calling it what it is also keeps the story honest: it is a Clifford + Pauli-noise sim, not a general sim. + +### Proposed location and name + +- Crate: **`pecos-simulators`** (same place as `SparseStab`, `StateVec`). +- Module: `src/dem_stab.rs` (or `fault_influence_sim.rs`). +- Public type: `DemStabSim` (bikeshed: `InfluenceSampler`, `FaultFrameSim`). + +### Two API shapes (offer both) + +#### Shape A -- batch / circuit-at-a-time (primary, honest API) + +Takes a fully-specified `DagCircuit` (or `TickCircuit`) + noise model + detector/observable definitions, returns batch shot results. This is the *true* shape of the algorithm; no per-gate illusion. + +```rust +let mut sim = DemStabSim::builder() + .circuit(&dag) + .noise(DepolarizingModel::uniform(p = 1e-3)) // or PauliLindblad, per-location, ... + .detectors(&detectors) + .observables(&observables) + .build()?; + +let shots = sim.sample_batch(num_shots, &mut rng); +// shots: { detector_flips, observable_flips, [optional] raw_measurement_record } +``` + +Internally: `DagFaultAnalyzer -> DagFaultInfluenceMap -> DemSamplerBuilder -> DemSampler::sample_batch`. + +#### Shape B -- `CliffordGateable` facade (compat shim) + +A thin record-and-replay wrapper that implements `CliffordGateable` / `QuantumSimulator`. Gate calls append to an internal `DagCircuit`. First measurement / `end_shot` / explicit `.finalize()` triggers one-time influence-map build; subsequent shots reuse the cached analysis. + +```rust +let mut sim = DemStabSimFacade::new(n_qubits) + .with_noise(DepolarizingModel::uniform(1e-3)); + +sim.h(&[q0]).cx(&[(q0, q1)]).mz(&[q0, q1]); // records +let result = sim.run_shot(&mut rng); // builds influence map lazily +``` + +Trade-off: per-gate method-chain is *not* cheap here (allocates into DAG). Document clearly: "prefer Shape A; Shape B exists only for trait-compatibility with code that assumes a streaming sim". + +### Noise model input + +Not locked to depolarizing. Start simple, extend via traits: + +- `UniformNoiseModel::depolarizing(p)` (already exists). +- `PerLocationNoiseModel { cx: (px, py, pz, pxx, ...), mz: p_flip, idle: (t1, t2 + tick_duration), ... }`. +- `PauliLindbladNoiseModel { generators: &[(support, rate)] }` -- maps learned IBM-style sparse Pauli-Lindblad to per-location effective Pauli rates; covers correlated noise. (See arXiv:2201.09866, 2311.15408.) +- `FromChannelOp(ChannelMatrix)` -- lowers an arbitrary CPTP Pauli-twirled channel to rates; rejects non-Pauli parts with a warning (keeps honest). +- Future: `FromLindblad(LindbladOp, gate_duration)` -- feeds a trajectory/exp-midpoint solver (item #7) to produce the Pauli channel per location. + +### Outputs + +- Detector flips (`Vec` per shot or bit-packed `PackedBits`). +- Observable flips. +- Optional: raw measurement record (toggleable via `MemBuilder` / measurement-noise-model path already present). +- Sampling statistics (already exposed via `SamplingStatistics`). +- Circuit-level Pauli error record per shot (useful for decoder dev / syndrome studies) -- TODO: confirm whether `NoisySampler::ShotResult::faults_fired` is exposed or internal. + +### Where PECOS should deliberately differ from Stim + +Stim is the inspiration; these are places to diverge on purpose: + +1. **First-class DAG / `TickCircuit` ingestion** -- no text round-trip, no external IR. PECOS's circuit types are the canonical input. +2. **No text DEM format as the API boundary.** Expose `DetectorErrorModel` (typed Rust) directly; string form is a serialization detail. +3. **Richer noise model hierarchy.** Pauli-Lindblad / channel / Lindblad-derived inputs as above, with clean trait plumbing instead of Stim's circuit-instruction-annotation-only model. +4. **Native hybrid escape hatch.** When the circuit has T / RZ / RX / ... gates outside the Clifford subgroup, either (a) refuse and suggest `CliffordRz` / STN / MAST, or (b) fall back to `CliffordRz`-driven DEM generation for those slices. Not a Stim feature. +5. **GPU path.** `pecos-gpu-sims` already has wgpu; DemSampler sampling is embarrassingly parallel (independent shots, independent mechanisms per shot). A wgpu backend for the batch sampler is natural. +6. **Tighter decoder handoff.** PECOS controls its own decoder stack, so the DEM type can carry extra metadata (detector spacetime coords, hypergraph decomposition hints) without standard-format constraints. + +### Implementation plan + +1. New module `pecos-simulators/src/dem_stab.rs`. +2. Re-export `DemStabSim` (Shape A) from `pecos-simulators` prelude. +3. Implement `QuantumSimulator` on a facade type `DemStabSimFacade` (Shape B) with internal `DagCircuit` accumulator. +4. Parity tests: Clifford + depolarizing circuit on `SparseStab + pecos-neo noise + Monte Carlo` vs `DemStabSim` (with and without statistical `compare_dems_statistical`) -- distributions must match. +5. Micro-benchmarks vs direct stabilizer Monte Carlo (expect large speedup once shots > ~100). +6. Python bindings through `pecos-rslib` (follow the `DemSamplerBuilder` existing path). +7. Docs: `docs/concepts/dem-stabilizer-simulator.md` explaining the algorithm and the Stim parallel explicitly. + +### Open questions + +- [ ] Name: `DemStabSim` vs `InfluenceSampler` vs `FaultFrameSim`. (Grug prefers names that say what it is; `DemStabSim` is fine.) +- [ ] Should Shape B exist at all, or is documentation + Shape A enough? (Grug lean: skip Shape B until a concrete consumer asks. Record-and-replay smells.) +- [ ] Per-shot raw measurement record: always on (matches Stim) or opt-in (memory cost)? Default off, opt-in. +- [ ] Seeding semantics when shots run in parallel (`rayon`): use per-shot seed derived from master seed (deterministic, embarrassingly parallel) vs thread-local split. + +--- + +## Next simulator proposal (after DemStabSim) + +Given the current stack, grug recommend **open-system / Lindblad + quantum-trajectory simulator** as the next build, for these reasons: + +1. **Bridges device physics to PECOS's existing DEM pipeline.** Efficient-Lindblad-synthesis techniques (arXiv:2502.03462) lower a per-gate Lindbladian to an effective Pauli channel per location, which feeds straight into the `DemStabSim` noise-model input above. This turns every real-device characterization run into a honest PECOS noise model. +2. **Only way to study coherent / non-Pauli errors honestly.** Pauli-twirling assumptions underlie every stabilizer-based sim; a trajectory sim is the validator. +3. **Leverages existing `pecos-neo` scaffolding.** `pecos-neo` already has composable channels and Monte Carlo parallel execution -- a Lindblad / MCWF solver slots in as a new channel-evaluation backend. +4. **Narrow, well-understood scope.** QuTiP, Dynamiqs, QuantumToolbox.jl are mature references; algorithm risk is low, the gain is PECOS-native performance + tight coupling with DEM generation. +5. **Practical leverage right now.** Researchers using PECOS on near-term hardware benchmarks pay a lot for Pauli-twirled approximations when what they actually want is "what does this T1/T2/over-rotation budget imply for my logical error rate". This closes that loop. + +Bosonic / CV (candidate #6 in the ranking) is bigger scope but lower near-term leverage per engineer-week; it makes sense *after* Lindblad lands, since a CV Lindblad solver is essentially the same core solver with bigger Hilbert spaces. + +Concrete next steps (separate design doc): +- Pick solver family (adaptive RK vs Magnus vs Krylov exp) for mid-size (N <= 10 qubits) Lindbladians. +- Define `LindbladOp` + `TrajectoryResult` types. +- Bridge API: `LindbladBackend::gate_channel(op, duration) -> PauliChannel` for DemStabSim consumption. +- Trajectory mode (MCWF / quantum jumps) for variance-reduced sampling. +- GPU path: start with rayon-parallel trajectories on CPU; wgpu later if cost justifies. + ## TODOs before formalizing - [x] Confirm `PauliProp` does not already extract DEMs -- correction: `pecos-qec::fault_tolerance::dem_builder` already does. From 292153d6b13bfbd614eb6363f5be0ea1bfc6fb09 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 11 Apr 2026 20:42:01 -0600 Subject: [PATCH 003/125] Anchor DemStabSim to sim() entry point; confirm build order; mark bosonic/photonic out of scope --- design/qec_sim_literature.md | 42 +++++++++++++++++++++++++++++------- 1 file changed, 34 insertions(+), 8 deletions(-) diff --git a/design/qec_sim_literature.md b/design/qec_sim_literature.md index 06f2937e5..68290d37f 100644 --- a/design/qec_sim_literature.md +++ b/design/qec_sim_literature.md @@ -274,14 +274,15 @@ The DemSampler today operates on a `DagFaultInfluenceMap` produced by circuit-le Given PECOS already has DemSampler, CliffordRz, STN/MAST, pecos-neo: -1. **Lindblad / trajectory backend** (#7) -- only honest way to study coherent / non-Pauli noise. Wraps nicely into DemBuilder via channel->Pauli-rate lowering (Efficient Lindblad synthesis, arXiv:2502.03462). Highest leverage. -2. **Bosonic / CV** (#6) -- bosonic codes are a major growth area; PECOS currently qubit-only. Biggest scope expansion. -3. **Stim cross-validation bridge for DemSampler** (revised #1) -- low effort, high value for regression testing. -4. **CliffordRz sparsification** (revised #4) -- confirmed absent, straightforward refinement of existing sim. -5. **Pauli-Lindblad correlated noise into DEM** (#9) -- IBM-style learned noise -> PECOS DEM pipeline. Good synergy with item 1. -6. **Pauli-based computation** (#5) -- matches FTQC resource accounting directly, good pairing with MAST. +1. **DemStabSim** (new module; wraps existing DemSampler/influence-map as a first-class backend via `sim()`) -- see proposal below. Build first. +2. **Lindblad / trajectory** (#7) -- only honest way to study coherent / non-Pauli noise; feeds DemStabSim via channel->Pauli-rate lowering (arXiv:2502.03462). Build second. +3. **Pauli-Lindblad correlated noise -> DEM** (#9) -- learned IBM-style noise as a DemStabSim input; small addition once #1 lands. +4. **CliffordRz sparsification** (revised #4) -- confirmed absent; standalone refinement, do when researcher hits the 2^t wall. +5. **Pauli-based computation** (#5) -- matches FTQC resource accounting; pairs with MAST. -Rest (matchgate, decision diagrams, fermion-native, quasiprobability, fusion-based) are narrower or more research-y. +**Out of scope.** Bosonic / CV (#6), photonic FBQC (#11) -- PECOS does not work on these areas. + +**Rest** (matchgate, decision diagrams, fermion-native, quasiprobability) are narrower or more research-y and not on the near-term path. --- @@ -301,6 +302,22 @@ Stim's core algorithm *is* "Pauli-frame propagation through a Clifford circuit w - Module: `src/dem_stab.rs` (or `fault_influence_sim.rs`). - Public type: `DemStabSim` (bikeshed: `InfluenceSampler`, `FaultFrameSim`). +### Integration with the `sim()` entry point + +`sim()` is the main simulation entry on both sides: + +- Rust: `crates/pecos-engines/src/sim_builder.rs:418` -- `pub fn sim(input: I) -> SimBuilder`. +- Python: `python/pecos-rslib/src/sim.rs:66` -- `pub fn sim(py, program) -> PySimBuilder`. + +DemStabSim must be selectable through `sim(circuit).backend(...)` / equivalent, not live as a sidecar API. Concretely: + +- Register `DemStabSim` as a backend variant in whatever enum / dispatch `SimBuilder` uses today (check `engine_builder::SimInput` and existing backends like `SparseStab`, `StateVec`). +- `sim(dag).dem_stab().noise(...).detectors(...).sample(n)` reads naturally at both call sites. +- The builder path is the ergonomic home for the noise-model hierarchy and detector/observable definitions. +- Python mirror: `pecos.sim(program).dem_stab().noise(...).sample(n)` via PyO3 bindings in `pecos-rslib`. + +**Action item.** Audit `SimBuilder` / `PySimBuilder` to confirm the shape of the backend-selection API before committing to a method name, so DemStabSim slots in next to existing backends consistently. + ### Two API shapes (offer both) #### Shape A -- batch / circuit-at-a-time (primary, honest API) @@ -383,6 +400,15 @@ Stim is the inspiration; these are places to diverge on purpose: --- +## Build order + +**Confirmed build order (2026-04-11):** + +1. **DemStabSim first.** Wraps existing infrastructure, slots into `sim()` as a new backend, highest near-term leverage for QEC research. No new algorithmic risk. +2. **Lindblad + quantum-trajectory second.** Closes the device-characterization -> effective-Pauli-channel -> DemStabSim loop. Anchored to `pecos-neo`. + +Out of scope for this roadmap (per project direction, 2026-04-11): **photonic / fusion-based**, **GKP / cat / bosonic codes**. Sections #6 and #11 remain documented for completeness but are not proposals. + ## Next simulator proposal (after DemStabSim) Given the current stack, grug recommend **open-system / Lindblad + quantum-trajectory simulator** as the next build, for these reasons: @@ -393,7 +419,7 @@ Given the current stack, grug recommend **open-system / Lindblad + quantum-traje 4. **Narrow, well-understood scope.** QuTiP, Dynamiqs, QuantumToolbox.jl are mature references; algorithm risk is low, the gain is PECOS-native performance + tight coupling with DEM generation. 5. **Practical leverage right now.** Researchers using PECOS on near-term hardware benchmarks pay a lot for Pauli-twirled approximations when what they actually want is "what does this T1/T2/over-rotation budget imply for my logical error rate". This closes that loop. -Bosonic / CV (candidate #6 in the ranking) is bigger scope but lower near-term leverage per engineer-week; it makes sense *after* Lindblad lands, since a CV Lindblad solver is essentially the same core solver with bigger Hilbert spaces. +Bosonic / CV and photonic FBQC are **out of scope** for the PECOS roadmap and are not candidates here. Concrete next steps (separate design doc): - Pick solver family (adaptive RK vs Magnus vs Krylov exp) for mid-size (N <= 10 qubits) Lindbladians. From 2e4903b56ddf078d52c6cee27259dd20ccbb1c66 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 11 Apr 2026 20:45:02 -0600 Subject: [PATCH 004/125] Add DemStabSim module skeleton and SimBuilder audit --- design/dem_stab_sim_skeleton.md | 216 ++++++++++++++++++++++++++++++++ design/qec_sim_literature.md | 33 +++++ 2 files changed, 249 insertions(+) create mode 100644 design/dem_stab_sim_skeleton.md diff --git a/design/dem_stab_sim_skeleton.md b/design/dem_stab_sim_skeleton.md new file mode 100644 index 000000000..bfdc357b3 --- /dev/null +++ b/design/dem_stab_sim_skeleton.md @@ -0,0 +1,216 @@ +# DemStabSim Module Skeleton + +Status: draft / skeleton +Target crate: `pecos-simulators` (parent) + engine integration in `pecos-engines` +Pairs with: `design/qec_sim_literature.md` (rationale, literature, build order) + +## Goals in one paragraph + +Make the existing `pecos-qec::fault_tolerance::dem_builder` pipeline (DagFaultAnalyzer -> DemBuilder / DemSamplerBuilder) selectable through `sim(program).quantum(dem_stab()).noise(...)` as a first-class quantum backend. It behaves as "Clifford + depolarizing-family noise, sampled via precomputed fault influence". Non-adaptive circuits only. No Stim dependency. + +## Crate layout + +Two parts, mirroring existing backends (`sparse_stab`, `state_vector`): + +``` +crates/pecos-simulators/src/dem_stab.rs (pure sim type) +crates/pecos-engines/src/dem_stab_engine.rs (QuantumEngine impl + builder) +``` + +Reason for split: other backends follow this pattern (e.g. `pecos-simulators::SparseStab` + `pecos-engines::SparseStabEngine`). + +## Public surface -- Rust + +### `pecos_simulators::dem_stab` + +```rust +pub struct DemStabSim { + dag: DagCircuit, + noise: Arc, + detectors: Vec, + observables: Vec, + + // Lazy-built, cached across shots. + sampler: OnceLock, + influence_map: OnceLock, +} + +impl DemStabSim { + pub fn builder() -> DemStabSimBuilder { DemStabSimBuilder::default() } + + /// Consume N shots. + pub fn sample_batch(&mut self, shots: usize, rng: &mut impl Rng) + -> DemStabShotBatch; + + pub fn detector_error_model(&mut self) -> &DetectorErrorModel; +} + +pub struct DemStabSimBuilder { /* private */ } + +impl DemStabSimBuilder { + pub fn circuit(mut self, dag: DagCircuit) -> Self; + pub fn tick_circuit(mut self, tc: TickCircuit) -> Self; // convenience + pub fn noise(mut self, n: N) -> Self; + pub fn detectors(mut self, d: Vec) -> Self; + pub fn observables(mut self, o: Vec) -> Self; + pub fn build(self) -> Result; +} + +pub struct DemStabShotBatch { + pub detector_flips: PackedBits2D, // shots x num_detectors + pub observable_flips: PackedBits2D, // shots x num_observables + pub measurement_record: Option, // opt-in, via MemBuilder + pub stats: SamplingStatistics, +} + +#[derive(Debug, thiserror::Error)] +pub enum DemStabError { + #[error("circuit contains classical feed-forward; use sparse_stab() for adaptive circuits")] + AdaptiveCircuit, + #[error("unsupported non-Clifford gate {0:?}; use CliffordRz or STN/MAST")] + NonClifford(GateType), + #[error(transparent)] + Builder(#[from] DemBuilderError), +} +``` + +### `DemStabNoiseModel` trait -- unified noise input + +```rust +/// Lowers to per-fault-location Pauli rates consumed by DemBuilder. +pub trait DemStabNoiseModel: Send + Sync + Debug { + fn noise_config(&self, circuit: &DagCircuit) -> NoiseConfig; +} + +// Concrete structs (same convention as DepolarizingNoise / BiasedDepolarizingNoise): +pub struct Uniform { pub p_1q: f64, pub p_2q: f64, pub p_meas: f64, pub p_prep: f64 } +pub struct PerLocation { /* HashMap */ } +pub struct PauliLindblad { pub generators: Vec<(PauliString, f64)> } // IBM-style learned +pub struct FromChannel { pub channel: ChannelMatrix } // Pauli-twirled lowering + +impl DemStabNoiseModel for Uniform { /* trivial */ } +impl DemStabNoiseModel for PerLocation { /* trivial */ } +impl DemStabNoiseModel for PauliLindblad { /* decompose generators */ } +impl DemStabNoiseModel for FromChannel { /* PTM -> Pauli rates, error on residual non-Pauli */ } +``` + +Future additions (no API impact today): `FromLindblad { op, duration }`, `FromTrajectorySamples { .. }` once item #7 (Lindblad sim) lands. + +## Engine integration -- Path A (record-and-replay) + +### `pecos_engines::dem_stab_engine` + +```rust +pub struct DemStabEngine { + n_qubits: usize, + dag: DagCircuit, + detectors: Vec, + observables: Vec, + noise: Option>, + seed: u64, + + // Built lazily on first shot_end. + sim: Option, + shot_rng: PecosRng, +} + +impl QuantumEngine for DemStabEngine { + fn process(&mut self, msg: ByteMessage) -> Result { + // 1. Decode ByteMessage into gates / measurements / shot-boundary. + // 2. If it is a gate -> push into self.dag (+ validate: no non-Clifford, no feedback). + // 3. If it is a measurement request: + // - on first call: lazy-build self.sim via DagFaultAnalyzer + DemSamplerBuilder. + // - sample one shot, return packed measurement outcomes as ByteMessage. + // - if circuit has NO measurements-used-classically, we can also defer to shot-end. + // 4. If it is a shot-reset: clear per-shot scratch (but NOT dag / sampler caches). + // (Re-entrant input = error: we only accept a single static program.) + } + fn set_seed(&mut self, seed: u64) { self.shot_rng = PecosRng::from_seed(seed); ... } + fn as_any(&self) -> &dyn Any { self } + fn as_any_mut(&mut self) -> &mut dyn Any { self } +} + +pub struct DemStabEngineBuilder { + noise: Option>, + detectors: Vec, + observables: Vec, + num_qubits: Option, +} + +impl QuantumEngineBuilder for DemStabEngineBuilder { + fn build(&mut self) -> Result, PecosError> { ... } + fn set_qubits_if_needed(&mut self, n: usize) { self.num_qubits.get_or_insert(n); } +} + +/// Free-function backend constructor, matching sparse_stab() / state_vector() convention. +#[must_use] +pub fn dem_stab() -> DemStabEngineBuilder { DemStabEngineBuilder::default() } +``` + +### Usage (Rust) + +```rust +use pecos_engines::{sim, dem_stab, ...}; + +let results = sim(program) + .quantum(dem_stab() + .detectors(detectors) + .observables(observables)) + .noise(dem_stab::Uniform { p_1q: 1e-3, p_2q: 5e-3, p_meas: 1e-3, p_prep: 1e-3 }) + .seed(42) + .run(100_000)?; +``` + +Note: the noise is set via `.noise(...)` at the `SimBuilder` level **but** DemStabSim needs it at circuit-build time, not per-gate. Solution: `DemStabEngine::build()` pulls the `NoiseModel` out of the orchestrator wiring and downcasts it to `DemStabNoiseModel` (using `as_any`). If the noise model isn't a `DemStabNoiseModel`, return `DemStabError::Builder(...)` with a clear message. Alternative: add `.dem_stab_noise(...)` on the builder to bypass the shared `.noise()` slot. Grug prefers the downcast -- keeps one noise API. + +### Python usage + +Mirror on the Python side in `pecos-rslib` / `pecos` package: + +```python +from pecos import sim +from pecos.backends import dem_stab +from pecos.noise import Uniform + +results = ( + sim(program) + .quantum(dem_stab().detectors(dets).observables(obs)) + .noise(Uniform(p_1q=1e-3, p_2q=5e-3, p_meas=1e-3, p_prep=1e-3)) + .seed(42) + .run(100_000) +) +``` + +## Rejection / validation + +DemStabEngine must reject circuits it cannot honestly handle. Two classes: + +1. **Adaptive (classical feed-forward).** If any gate's application depends on a prior measurement outcome, reject. +2. **Non-Clifford.** T / RZ / RX(theta) / etc. reject. + +Rejection happens in `process()` at ByteMessage decode time -- not at `build()` -- because the DAG is streamed in. Clear error messages that name the offending gate and point to `sparse_stab()` + `pecos-neo` or `CliffordRz` / STN as appropriate. + +## Tests (initial) + +1. **Parity test (core).** Small distance-3 repetition-code / surface-code memory experiment. Run both: + - `sim(prog).quantum(sparse_stab()).noise(DepolarizingNoise{p}).run(N)` with N = 1e5 shots. + - `sim(prog).quantum(dem_stab().detectors(...).observables(...)).noise(Uniform{...})`. + Assert detector-flip and logical-error-rate distributions match within binomial CI. Reuse `compare_dems_statistical` machinery. +2. **Rejection tests.** Assert `DemStabError::AdaptiveCircuit` on a feed-forward circuit and `NonClifford` on a T-gate circuit. +3. **DEM export parity.** Build the DEM via `DemBuilder` directly and via `DemStabSim::detector_error_model()`; assert equal via existing `compare_dems_exact`. +4. **Determinism.** Same seed, same shots -- identical results across runs. +5. **Benchmark.** `criterion` bench vs `sparse_stab` Monte Carlo for increasing N (expect crossover ~100 shots, large asymptotic speedup). + +## Out of scope for v1 + +- Shape B (record-and-replay `CliffordGateable` facade on `DemStabSim` struct itself). +- Non-Clifford hybrid escape (falling back to `CliffordRz` for RZ slices). Land as v2 once basic path proven. +- GPU sampling via wgpu. Natural follow-up once CPU numbers are known. +- Lindblad-derived noise input. Blocked on trajectory sim (item #7 in literature survey). + +## Open questions + +- [ ] Should the detectors/observables live on the `DemStabEngine` builder (as drafted) or on the program IR itself (HUGR/QASM annotations)? The latter is cleaner long-term but out of scope for v1. +- [ ] `Path B` batch fast-path: useful right away (bypass classical engine) or premature? Grug lean premature -- do Path A, measure, revisit. +- [ ] How do we want to surface the DEM object for decoder hand-off? Return it from `run()` alongside shots? Provide a sidecar `.build_dem_only()` method? Likely both. +- [ ] Seeding semantics for parallel shot batches (`rayon`): per-shot seed = master_seed XOR shot_idx is deterministic and trivially parallelizable. Default to that. diff --git a/design/qec_sim_literature.md b/design/qec_sim_literature.md index 68290d37f..1b29a0fbb 100644 --- a/design/qec_sim_literature.md +++ b/design/qec_sim_literature.md @@ -302,6 +302,39 @@ Stim's core algorithm *is* "Pauli-frame propagation through a Clifford circuit w - Module: `src/dem_stab.rs` (or `fault_influence_sim.rs`). - Public type: `DemStabSim` (bikeshed: `InfluenceSampler`, `FaultFrameSim`). +### SimBuilder audit (2026-04-11) + +Findings from `crates/pecos-engines/src/sim_builder.rs` and `python/pecos-rslib/src/sim.rs`: + +**Rust shape.** `SimBuilder` holds four pieces: `classical_builder` (required), `quantum_builder` (default `SparseStabEngine`), `noise_builder` (default `PassThroughNoiseModel`), `config`. Backend registration convention is a free function returning a builder: + +```rust +.quantum(sparse_stab()) // IntoQuantumEngineBuilder +.quantum(state_vector()) // same pattern +.noise(DepolarizingNoise { p: 0.001 }) // IntoNoiseModel +``` + +**`QuantumEngine` trait is streaming.** It's a `process(ByteMessage) -> ByteMessage` interface driven per-tick by the classical engine, with the noise model intercepting `ByteMessage`s before they hit the quantum side. This is a fundamental fit-shape constraint for DemStabSim. + +**Python shape.** `sim(program)` dispatches on program type (QASM / QIS / HUGR / PHIR) and each variant carries a `quantum_engine_builder: Option<...>` slot -- same backend-selection pattern. + +### Implication: two honest integration paths + +Because `QuantumEngine` is streaming and DemStabSim is batch-by-nature, grug sees two options: + +**Path A -- Record-and-replay `QuantumEngine` impl (recommended first step).** +`DemStabSimEngine` implements `QuantumEngine` by buffering all incoming `ByteMessage`s into an internal `DagCircuit`. On the first "end of circuit" signal (or lazy on first measurement query), it runs `DagFaultAnalyzer` -> `DemSamplerBuilder::build` once and caches the sampler. Subsequent shots short-circuit via `DemSampler::sample_batch`. Zero orchestrator changes; slots straight into `sim(program).quantum(dem_stab()).noise(...)`. + +Hard limitation: **only valid for non-adaptive circuits** (no classical feed-forward affecting gate sequence across shots). That is fine for static syndrome-extraction memory experiments, which is most standard QEC research. DemStabSim must *reject* circuits where the ByteMessage stream depends on mid-circuit measurement outcomes, and clearly redirect users to `sparse_stab()` + `pecos-neo` for adaptive circuits. + +**Path B -- Batch-mode fast-path (later).** +Extend `SimBuilder` with a batch-execution branch that, when a batch-capable backend is set, bypasses the per-shot classical loop entirely and hands the whole compiled program to the backend once. More invasive, semantically honest, unlocks GPU batch. Do this only after Path A proves out and numbers justify the orchestrator surgery. + +Action items: +- [ ] Confirm how end-of-shot is signalled to `QuantumEngine` today (look for `reset()` / shot-boundary markers in `ByteMessage`). +- [ ] Confirm DemSampler cache can be safely reused across `MonteCarloEngine::run()` calls with fresh RNG (should be yes). +- [ ] Decide rejection mechanics: return `PecosError::Input` on first classical-feedback instruction, or pre-scan once at build. + ### Integration with the `sim()` entry point `sim()` is the main simulation entry on both sides: From 1172a95edcb801695408b0dc3cd1e996fed1d522 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 11 Apr 2026 20:48:56 -0600 Subject: [PATCH 005/125] Promote Path B to v2 roadmap; sketch batch-mode design --- design/dem_stab_sim_skeleton.md | 27 +++++++++++++++++++++++++-- design/qec_sim_literature.md | 4 ++-- 2 files changed, 27 insertions(+), 4 deletions(-) diff --git a/design/dem_stab_sim_skeleton.md b/design/dem_stab_sim_skeleton.md index bfdc357b3..30e27e180 100644 --- a/design/dem_stab_sim_skeleton.md +++ b/design/dem_stab_sim_skeleton.md @@ -203,11 +203,34 @@ Rejection happens in `process()` at ByteMessage decode time -- not at `build()` ## Out of scope for v1 -- Shape B (record-and-replay `CliffordGateable` facade on `DemStabSim` struct itself). -- Non-Clifford hybrid escape (falling back to `CliffordRz` for RZ slices). Land as v2 once basic path proven. +- **Path B batch-mode fast-path** -- planned v2. Does the orchestrator surgery to let DemStabSim skip the per-shot streaming loop entirely. Grug do this *after* Path A lands so v1 doesn't drag along an orchestrator redesign. +- Non-Clifford hybrid escape (falling back to `CliffordRz` for RZ slices). Land as v2+ once basic path proven. - GPU sampling via wgpu. Natural follow-up once CPU numbers are known. - Lindblad-derived noise input. Blocked on trajectory sim (item #7 in literature survey). +## v2: Path B batch-mode fast-path (sketch) + +Kept in this doc so the v1 design does not paint v2 into a corner. + +**Goal.** When `SimBuilder` is configured with a batch-capable quantum backend, bypass the per-shot classical-engine loop and feed the whole compiled program to the backend in one call. + +**Mechanism.** +- New trait in `pecos-engines`, e.g. `BatchQuantumEngine: QuantumEngine` with `run_shots(&mut self, shots: usize, rng: &mut dyn RngCore) -> ShotVec`. Default impl falls through to the current streaming loop for backends that do not implement it natively. +- `MonteCarloEngine::run(shots)` downcasts on its `QuantumEngine` trait object: if batch-capable and circuit is static (no classical feed-forward from the classical engine), call `run_shots` once; otherwise current per-shot loop. +- DemStabEngine implements `BatchQuantumEngine` natively: the internal sampler already does `sample_batch`, so `run_shots` is one call into `DemSampler::sample_batch` with a single RNG split. +- Preserves the `sim(program).quantum(dem_stab()).noise(...).run(N)` user API -- the path split is internal. + +**Design constraints v1 must preserve:** +- `DemStabEngine` already owns the built `DemSampler` across shots (Path A caches it). Path B just exposes a batch entry point alongside the streaming one. No duplication. +- DAG must be fully captured before batch execution begins -- identical to Path A's lazy-build trigger. Path A's record step is reused. +- `DemStabShotBatch` (the v1 return type of the sim) becomes the natural backing type for the batch return path. + +**What v2 does not need v1 to commit to:** +- Final form of `BatchQuantumEngine` trait (single method vs. split detect/observable/measurement). +- Whether batch fast-path is opt-in via config or auto-enabled on downcast success. + +Decide at the start of v2, with Path A's numbers as evidence. + ## Open questions - [ ] Should the detectors/observables live on the `DemStabEngine` builder (as drafted) or on the program IR itself (HUGR/QASM annotations)? The latter is cleaner long-term but out of scope for v1. diff --git a/design/qec_sim_literature.md b/design/qec_sim_literature.md index 1b29a0fbb..833a95d6f 100644 --- a/design/qec_sim_literature.md +++ b/design/qec_sim_literature.md @@ -327,8 +327,8 @@ Because `QuantumEngine` is streaming and DemStabSim is batch-by-nature, grug see Hard limitation: **only valid for non-adaptive circuits** (no classical feed-forward affecting gate sequence across shots). That is fine for static syndrome-extraction memory experiments, which is most standard QEC research. DemStabSim must *reject* circuits where the ByteMessage stream depends on mid-circuit measurement outcomes, and clearly redirect users to `sparse_stab()` + `pecos-neo` for adaptive circuits. -**Path B -- Batch-mode fast-path (later).** -Extend `SimBuilder` with a batch-execution branch that, when a batch-capable backend is set, bypasses the per-shot classical loop entirely and hands the whole compiled program to the backend once. More invasive, semantically honest, unlocks GPU batch. Do this only after Path A proves out and numbers justify the orchestrator surgery. +**Path B -- Batch-mode fast-path (confirmed on roadmap, after Path A).** +Extend `SimBuilder` with a batch-execution branch that, when a batch-capable backend is set, bypasses the per-shot classical loop entirely and hands the whole compiled program to the backend once. More invasive, semantically honest, unlocks GPU batch. Both paths are on the roadmap: **Path A first** (record-and-replay inside the streaming `QuantumEngine` shape) to land the backend with minimal orchestrator churn, **Path B second** once Path A proves the numbers so the orchestrator surgery is paid for by real speedups. Action items: - [ ] Confirm how end-of-shot is signalled to `QuantumEngine` today (look for `reset()` / shot-boundary markers in `ByteMessage`). From ee4cba94235371a5a2b18e619003b44f2937dc06 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 11 Apr 2026 20:56:46 -0600 Subject: [PATCH 006/125] Add DemStabSim v0 pure-sim module with parity tests Wraps existing DagFaultAnalyzer + DemSamplerBuilder + DemSampler pipeline behind a single builder-style type. Lives in pecos-qec alongside the DEM machinery it wraps (input/output shape is QEC-specific: detectors and observables, not generic quantum state). Parity test confirms identical shot batches vs the raw pipeline given equal seeds. --- crates/pecos-qec/src/dem_stab.rs | 217 +++++++++++++++++++++++ crates/pecos-qec/src/lib.rs | 3 + crates/pecos-qec/tests/dem_stab_tests.rs | 155 ++++++++++++++++ design/dem_stab_sim_skeleton.md | 8 +- 4 files changed, 380 insertions(+), 3 deletions(-) create mode 100644 crates/pecos-qec/src/dem_stab.rs create mode 100644 crates/pecos-qec/tests/dem_stab_tests.rs diff --git a/crates/pecos-qec/src/dem_stab.rs b/crates/pecos-qec/src/dem_stab.rs new file mode 100644 index 000000000..c9488613e --- /dev/null +++ b/crates/pecos-qec/src/dem_stab.rs @@ -0,0 +1,217 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! `DemStabSim` -- Clifford + depolarizing-family noise simulator backed by DEM sampling. +//! +//! Wraps the existing DAG -> fault-influence -> DEM-sampler pipeline as a single +//! simulator type that consumes a static [`DagCircuit`] plus detector / observable +//! definitions plus a [`NoiseConfig`] and produces shot batches of detector and +//! observable flips. +//! +//! # Scope +//! +//! Clifford circuits only, no classical feed-forward. For adaptive circuits use +//! `sparse_stab` + `pecos-neo` instead. For non-Clifford circuits use `CliffordRz`, +//! `STN`, or `MAST`. +//! +//! # Example +//! +//! ``` +//! use pecos_qec::dem_stab::DemStabSim; +//! use pecos_qec::fault_tolerance::dem_builder::{DetectorDef, LogicalObservable, NoiseConfig}; +//! use pecos_quantum::DagCircuit; +//! use rand::SeedableRng; +//! use rand::rngs::SmallRng; +//! +//! let mut dag = DagCircuit::new(); +//! dag.pz(&[2]); +//! dag.cx(&[(0, 2)]); +//! dag.cx(&[(1, 2)]); +//! dag.mz(&[2]); +//! +//! let sim = DemStabSim::builder() +//! .circuit(dag) +//! .noise(NoiseConfig::uniform(0.01)) +//! .detectors(vec![DetectorDef::new(0).with_records([-1])]) +//! .build() +//! .unwrap(); +//! +//! let mut rng = SmallRng::seed_from_u64(42); +//! let batch = sim.sample_batch(100, &mut rng); +//! assert_eq!(batch.detector_flips.len(), 100); +//! ``` + +use crate::fault_tolerance::dem_builder::{ + DemSampler, DemSamplerBuilder, DetectorDef, LogicalObservable, NoiseConfig, +}; +use crate::fault_tolerance::propagator::DagFaultAnalyzer; +use pecos_quantum::DagCircuit; +use rand_core::Rng; +use thiserror::Error; + +/// Errors that can occur when building a [`DemStabSim`]. +#[derive(Debug, Error)] +pub enum DemStabError { + /// Builder called without a circuit. + #[error("DemStabSim requires a circuit; call .circuit(dag) before .build()")] + MissingCircuit, +} + +/// Shot-batch output from [`DemStabSim::sample_batch`]. +/// +/// `detector_flips[i]` is the bit-vector of detector outcomes for shot `i` (length +/// equals the number of registered detectors). `observable_flips[i]` is the +/// corresponding observable outcomes. +#[derive(Debug, Clone)] +pub struct DemStabShotBatch { + /// Per-shot detector flip vectors. Outer length = `num_shots`, inner length = `num_detectors`. + pub detector_flips: Vec>, + /// Per-shot observable flip vectors. Outer length = `num_shots`, inner length = `num_observables`. + pub observable_flips: Vec>, +} + +/// Clifford + depolarizing-family noise simulator backed by DEM sampling. +/// +/// Built once via [`DemStabSim::builder`], sampled many times via [`Self::sample_batch`]. +/// The underlying [`DemSampler`] is constructed eagerly at build time; subsequent +/// shots reuse the cached mechanism table. +#[derive(Debug, Clone)] +pub struct DemStabSim { + sampler: DemSampler, +} + +impl DemStabSim { + /// Start building a [`DemStabSim`]. + #[must_use] + pub fn builder() -> DemStabSimBuilder { + DemStabSimBuilder::default() + } + + /// Number of registered detectors. + #[must_use] + pub fn num_detectors(&self) -> usize { + self.sampler.num_detectors() + } + + /// Number of registered observables. + #[must_use] + pub fn num_observables(&self) -> usize { + self.sampler.num_observables() + } + + /// Number of error mechanisms in the compiled DEM. + #[must_use] + pub fn num_mechanisms(&self) -> usize { + self.sampler.num_mechanisms() + } + + /// Access the underlying [`DemSampler`] for advanced use (e.g. statistics-only APIs). + #[must_use] + pub fn sampler(&self) -> &DemSampler { + &self.sampler + } + + /// Sample `num_shots` independent shots from the compiled DEM. + #[must_use] + pub fn sample_batch(&self, num_shots: usize, rng: &mut R) -> DemStabShotBatch { + let (detector_flips, observable_flips) = self.sampler.sample_batch(num_shots, rng); + DemStabShotBatch { + detector_flips, + observable_flips, + } + } +} + +/// Builder for [`DemStabSim`]. +#[derive(Debug, Default)] +pub struct DemStabSimBuilder { + circuit: Option, + noise: NoiseConfig, + detectors: Vec, + observables: Vec, + measurement_order: Option>, +} + +impl DemStabSimBuilder { + /// Set the circuit. Required. + #[must_use] + pub fn circuit(mut self, dag: DagCircuit) -> Self { + self.circuit = Some(dag); + self + } + + /// Set the noise configuration. + #[must_use] + pub fn noise(mut self, config: NoiseConfig) -> Self { + self.noise = config; + self + } + + /// Register detectors by [`DetectorDef`]. + #[must_use] + pub fn detectors(mut self, detectors: Vec) -> Self { + self.detectors = detectors; + self + } + + /// Register logical observables by [`LogicalObservable`]. + #[must_use] + pub fn observables(mut self, observables: Vec) -> Self { + self.observables = observables; + self + } + + /// Set the measurement order mapping from a `TickCircuit` (advanced). + #[must_use] + pub fn measurement_order(mut self, order: Vec) -> Self { + self.measurement_order = Some(order); + self + } + + /// Build the [`DemStabSim`], consuming the builder. + /// + /// # Errors + /// + /// Returns [`DemStabError::MissingCircuit`] if no circuit was set. + pub fn build(self) -> Result { + let dag = self.circuit.ok_or(DemStabError::MissingCircuit)?; + + let analyzer = DagFaultAnalyzer::new(&dag); + let influence_map = analyzer.build_influence_map(); + + let detector_records: Vec> = + self.detectors.iter().map(|d| d.records.to_vec()).collect(); + let observable_records: Vec> = self + .observables + .iter() + .map(|o| o.records.to_vec()) + .collect(); + + let mut builder = DemSamplerBuilder::new(&influence_map) + .with_noise( + self.noise.p1, + self.noise.p2, + self.noise.p_meas, + self.noise.p_init, + ) + .with_detector_records(detector_records) + .with_observable_records(observable_records); + + if let Some(order) = self.measurement_order { + builder = builder.with_measurement_order(order); + } + + Ok(DemStabSim { + sampler: builder.build(), + }) + } +} diff --git a/crates/pecos-qec/src/lib.rs b/crates/pecos-qec/src/lib.rs index 9ac2a135e..38dc57ae6 100644 --- a/crates/pecos-qec/src/lib.rs +++ b/crates/pecos-qec/src/lib.rs @@ -63,6 +63,7 @@ //! assert_eq!(analysis.undetectable_logical, 0); //! ``` +pub mod dem_stab; pub mod distance; pub mod fault_tolerance; pub mod geometry; @@ -71,6 +72,8 @@ pub mod stabilizer_code; pub mod stabilizer_code_spec; pub mod surface; +pub use dem_stab::{DemStabError, DemStabShotBatch, DemStabSim, DemStabSimBuilder}; + pub use distance::{ DistanceResult, DistanceSearchConfig, LogicalOperatorInfo, WeightedPauliIterator, calculate_distance, find_min_weight_logicals, find_min_weight_logicals_with_info, diff --git a/crates/pecos-qec/tests/dem_stab_tests.rs b/crates/pecos-qec/tests/dem_stab_tests.rs new file mode 100644 index 000000000..35af1306f --- /dev/null +++ b/crates/pecos-qec/tests/dem_stab_tests.rs @@ -0,0 +1,155 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Integration tests for `DemStabSim`. +//! +//! Parity: `DemStabSim` must produce identical shot batches to the raw +//! `DagFaultAnalyzer` + `DemSamplerBuilder` pipeline given equal inputs and seeds. + +use pecos_qec::dem_stab::{DemStabError, DemStabSim}; +use pecos_qec::fault_tolerance::dem_builder::{ + DemSamplerBuilder, DetectorDef, LogicalObservable, NoiseConfig, +}; +use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; +use pecos_quantum::DagCircuit; +use rand::SeedableRng; +use rand::rngs::SmallRng; + +fn repetition_code_circuit() -> DagCircuit { + let mut dag = DagCircuit::new(); + // 3 data qubits (0, 1, 2), 2 ancillas (3, 4) + dag.pz(&[3]); + dag.pz(&[4]); + dag.cx(&[(0, 3)]); + dag.cx(&[(1, 3)]); + dag.cx(&[(1, 4)]); + dag.cx(&[(2, 4)]); + dag.mz(&[3]); + dag.mz(&[4]); + dag +} + +fn detectors() -> Vec { + vec![ + DetectorDef::new(0).with_records([-2]), + DetectorDef::new(1).with_records([-1]), + ] +} + +fn observables() -> Vec { + vec![LogicalObservable::new(0).with_records([-2, -1])] +} + +#[test] +fn builder_rejects_missing_circuit() { + let err = DemStabSim::builder().build().unwrap_err(); + assert!(matches!(err, DemStabError::MissingCircuit)); +} + +#[test] +fn zero_noise_produces_zero_mechanisms() { + let sim = DemStabSim::builder() + .circuit(repetition_code_circuit()) + .noise(NoiseConfig::uniform(0.0)) + .detectors(detectors()) + .observables(observables()) + .build() + .unwrap(); + + assert_eq!(sim.num_mechanisms(), 0); + assert_eq!(sim.num_detectors(), 2); + assert_eq!(sim.num_observables(), 1); +} + +#[test] +fn parity_with_raw_pipeline() { + let noise = NoiseConfig::uniform(0.01); + let shots = 512; + let seed = 0xDEAD_BEEF_u64; + + // Path 1: DemStabSim. + let sim = DemStabSim::builder() + .circuit(repetition_code_circuit()) + .noise(noise) + .detectors(detectors()) + .observables(observables()) + .build() + .unwrap(); + let mut rng1 = SmallRng::seed_from_u64(seed); + let batch = sim.sample_batch(shots, &mut rng1); + + // Path 2: raw pipeline, identical inputs + identical RNG seed. + let dag = repetition_code_circuit(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence_map = analyzer.build_influence_map(); + let det_records: Vec> = detectors().iter().map(|d| d.records.to_vec()).collect(); + let obs_records: Vec> = observables().iter().map(|o| o.records.to_vec()).collect(); + let sampler = DemSamplerBuilder::new(&influence_map) + .with_noise(noise.p1, noise.p2, noise.p_meas, noise.p_init) + .with_detector_records(det_records) + .with_observable_records(obs_records) + .build(); + let mut rng2 = SmallRng::seed_from_u64(seed); + let (det_raw, obs_raw) = sampler.sample_batch(shots, &mut rng2); + + assert_eq!(batch.detector_flips, det_raw); + assert_eq!(batch.observable_flips, obs_raw); +} + +#[test] +fn shot_batch_shape_is_correct() { + let sim = DemStabSim::builder() + .circuit(repetition_code_circuit()) + .noise(NoiseConfig::uniform(0.005)) + .detectors(detectors()) + .observables(observables()) + .build() + .unwrap(); + + let mut rng = SmallRng::seed_from_u64(7); + let batch = sim.sample_batch(16, &mut rng); + + assert_eq!(batch.detector_flips.len(), 16); + assert_eq!(batch.observable_flips.len(), 16); + for row in &batch.detector_flips { + assert_eq!(row.len(), sim.num_detectors()); + } + for row in &batch.observable_flips { + assert_eq!(row.len(), sim.num_observables()); + } +} + +#[test] +fn nonzero_noise_yields_some_flips() { + // Sanity check: at p=0.1 with 1000 shots we should see plenty of flips. + let sim = DemStabSim::builder() + .circuit(repetition_code_circuit()) + .noise(NoiseConfig::uniform(0.1)) + .detectors(detectors()) + .observables(observables()) + .build() + .unwrap(); + + let mut rng = SmallRng::seed_from_u64(123); + let batch = sim.sample_batch(1000, &mut rng); + + let total_det_flips: usize = batch + .detector_flips + .iter() + .map(|row| row.iter().filter(|&&b| b).count()) + .sum(); + + assert!( + total_det_flips > 0, + "expected some detector flips at p=0.1 over 1000 shots" + ); +} diff --git a/design/dem_stab_sim_skeleton.md b/design/dem_stab_sim_skeleton.md index 30e27e180..e857aa848 100644 --- a/design/dem_stab_sim_skeleton.md +++ b/design/dem_stab_sim_skeleton.md @@ -10,14 +10,16 @@ Make the existing `pecos-qec::fault_tolerance::dem_builder` pipeline (DagFaultAn ## Crate layout -Two parts, mirroring existing backends (`sparse_stab`, `state_vector`): +Two parts: ``` -crates/pecos-simulators/src/dem_stab.rs (pure sim type) +crates/pecos-qec/src/dem_stab.rs (pure sim type; peer of fault_tolerance) crates/pecos-engines/src/dem_stab_engine.rs (QuantumEngine impl + builder) ``` -Reason for split: other backends follow this pattern (e.g. `pecos-simulators::SparseStab` + `pecos-engines::SparseStabEngine`). +**Crate pivot from initial skeleton (2026-04-11).** `pecos-qec` depends on `pecos-simulators` (one-way), so a `dem_stab` module inside `pecos-simulators` would have to pull `pecos-qec` upward and create a cycle. The DemSampler / DemBuilder / DagFaultAnalyzer machinery already lives in `pecos-qec`, and DemStabSim is a thin wrapper over that machinery -- so `pecos-qec::dem_stab` is both the only legal home and the honest one. It sits as a peer of `fault_tolerance`, not inside it (it *uses* fault tolerance rather than being part of it). + +Other backends keep the `pecos-simulators` + `pecos-engines` split (`SparseStab` + `SparseStabEngine`); DemStabSim's split is `pecos-qec` + `pecos-engines` instead. Same orchestration pattern either way. ## Public surface -- Rust From 4c81e3bc43f5a7149930e7109ba93f87a471b021 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 11 Apr 2026 21:02:25 -0600 Subject: [PATCH 007/125] Add MemStabSim v0 sibling module + parity tests MemStabSim wraps MemBuilder + MeasurementNoiseModel for raw-measurement sampling, parallel to DemStabSim which wraps DemSampler for detector-level sampling. Same builder pattern; different aggregation level. MemStabSim is the honest shape for engine integration (classical engine wants raw measurement outcomes). DemStabSim stays as the batch research API for detector events. --- crates/pecos-qec/src/lib.rs | 2 + crates/pecos-qec/src/mem_stab.rs | 197 +++++++++++++++++++++++ crates/pecos-qec/tests/mem_stab_tests.rs | 142 ++++++++++++++++ 3 files changed, 341 insertions(+) create mode 100644 crates/pecos-qec/src/mem_stab.rs create mode 100644 crates/pecos-qec/tests/mem_stab_tests.rs diff --git a/crates/pecos-qec/src/lib.rs b/crates/pecos-qec/src/lib.rs index 38dc57ae6..b14890743 100644 --- a/crates/pecos-qec/src/lib.rs +++ b/crates/pecos-qec/src/lib.rs @@ -68,11 +68,13 @@ pub mod distance; pub mod fault_tolerance; pub mod geometry; pub mod logical_discovery; +pub mod mem_stab; pub mod stabilizer_code; pub mod stabilizer_code_spec; pub mod surface; pub use dem_stab::{DemStabError, DemStabShotBatch, DemStabSim, DemStabSimBuilder}; +pub use mem_stab::{MemStabError, MemStabSim, MemStabSimBuilder}; pub use distance::{ DistanceResult, DistanceSearchConfig, LogicalOperatorInfo, WeightedPauliIterator, diff --git a/crates/pecos-qec/src/mem_stab.rs b/crates/pecos-qec/src/mem_stab.rs new file mode 100644 index 000000000..57b33fab6 --- /dev/null +++ b/crates/pecos-qec/src/mem_stab.rs @@ -0,0 +1,197 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! `MemStabSim` -- Clifford + depolarizing-family noise simulator that samples +//! **raw measurement outcomes** via a Measurement Noise Model (MNM). +//! +//! Sibling to [`crate::dem_stab::DemStabSim`]. Same underlying fault-influence +//! machinery, different aggregation level: +//! +//! | | `DemStabSim` | `MemStabSim` | +//! |---|---|---| +//! | Output | Detector + observable flips | Raw measurement outcomes | +//! | Use case | Research batch / decoder input | Classical-engine-facing backend | +//! | Backing primitive | `DemSampler` (DEM mechanisms) | `MeasurementNoiseModel` (MNM mechanisms) | +//! +//! Use `MemStabSim` when a classical control engine needs per-shot raw measurement +//! records (and will compute its own detectors/observables from them). Use +//! `DemStabSim` when you just want detector events for a decoder. +//! +//! # Scope +//! +//! Clifford circuits only, no classical feed-forward. For adaptive circuits use +//! `sparse_stab` + `pecos-neo` instead. For non-Clifford circuits use `CliffordRz`, +//! `STN`, or `MAST`. +//! +//! # Example +//! +//! ``` +//! use pecos_qec::mem_stab::MemStabSim; +//! use pecos_qec::fault_tolerance::dem_builder::NoiseConfig; +//! use pecos_quantum::DagCircuit; +//! use rand::SeedableRng; +//! use rand::rngs::SmallRng; +//! +//! let mut dag = DagCircuit::new(); +//! dag.pz(&[2]); +//! dag.cx(&[(0, 2)]); +//! dag.cx(&[(1, 2)]); +//! dag.mz(&[2]); +//! +//! let sim = MemStabSim::builder() +//! .circuit(dag) +//! .noise(NoiseConfig::uniform(0.01)) +//! .build() +//! .unwrap(); +//! +//! let mut rng = SmallRng::seed_from_u64(42); +//! let outcomes = sim.sample(&mut rng); +//! assert_eq!(outcomes.len(), sim.num_measurements()); +//! ``` + +use crate::fault_tolerance::dem_builder::{MeasurementNoiseModel, MemBuilder, NoiseConfig}; +use crate::fault_tolerance::propagator::DagFaultAnalyzer; +use pecos_quantum::DagCircuit; +use rand::Rng; +use thiserror::Error; + +/// Errors that can occur when building a [`MemStabSim`]. +#[derive(Debug, Error)] +pub enum MemStabError { + /// Builder called without a circuit. + #[error("MemStabSim requires a circuit; call .circuit(dag) before .build()")] + MissingCircuit, +} + +/// Clifford + depolarizing-family noise simulator that samples raw measurement outcomes. +/// +/// Built once via [`MemStabSim::builder`], sampled many times via [`Self::sample`] or +/// [`Self::sample_batch`]. The underlying [`MeasurementNoiseModel`] is constructed +/// eagerly at build time. +#[derive(Debug, Clone)] +pub struct MemStabSim { + mnm: MeasurementNoiseModel, +} + +impl MemStabSim { + /// Start building a [`MemStabSim`]. + #[must_use] + pub fn builder() -> MemStabSimBuilder { + MemStabSimBuilder::default() + } + + /// Number of measurements in the compiled circuit. + #[must_use] + pub fn num_measurements(&self) -> usize { + self.mnm.num_measurements + } + + /// Number of error mechanisms in the compiled MNM. + #[must_use] + pub fn num_mechanisms(&self) -> usize { + self.mnm.mechanisms.len() + } + + /// Access the underlying [`MeasurementNoiseModel`]. + #[must_use] + pub fn mnm(&self) -> &MeasurementNoiseModel { + &self.mnm + } + + /// Sample one shot of raw measurement outcomes. + /// + /// Length of the returned vector equals [`Self::num_measurements`]. + pub fn sample(&self, rng: &mut R) -> Vec { + self.mnm.sample(rng) + } + + /// Sample one shot into a preallocated buffer. + /// + /// `outcomes` must have length equal to [`Self::num_measurements`]; the buffer + /// is cleared before sampling. + pub fn sample_into(&self, outcomes: &mut [bool], rng: &mut R) { + self.mnm.sample_into(outcomes, rng); + } + + /// Sample `num_shots` independent shots. + /// + /// Returns a `Vec` of length `num_shots`; each inner vector has length + /// [`Self::num_measurements`]. + #[must_use] + pub fn sample_batch(&self, num_shots: usize, rng: &mut R) -> Vec> { + let mut out = Vec::with_capacity(num_shots); + let mut buf = vec![false; self.num_measurements()]; + for _ in 0..num_shots { + self.mnm.sample_into(&mut buf, rng); + out.push(buf.clone()); + } + out + } +} + +/// Builder for [`MemStabSim`]. +#[derive(Debug, Default)] +pub struct MemStabSimBuilder { + circuit: Option, + noise: NoiseConfig, + measurement_order: Option>, +} + +impl MemStabSimBuilder { + /// Set the circuit. Required. + #[must_use] + pub fn circuit(mut self, dag: DagCircuit) -> Self { + self.circuit = Some(dag); + self + } + + /// Set the noise configuration. + #[must_use] + pub fn noise(mut self, config: NoiseConfig) -> Self { + self.noise = config; + self + } + + /// Set the measurement order mapping from a `TickCircuit` (advanced). + #[must_use] + pub fn measurement_order(mut self, order: Vec) -> Self { + self.measurement_order = Some(order); + self + } + + /// Build the [`MemStabSim`], consuming the builder. + /// + /// # Errors + /// + /// Returns [`MemStabError::MissingCircuit`] if no circuit was set. + pub fn build(self) -> Result { + let dag = self.circuit.ok_or(MemStabError::MissingCircuit)?; + + let analyzer = DagFaultAnalyzer::new(&dag); + let influence_map = analyzer.build_influence_map(); + + let mut builder = MemBuilder::new(&influence_map).with_noise( + self.noise.p1, + self.noise.p2, + self.noise.p_meas, + self.noise.p_init, + ); + + if let Some(order) = self.measurement_order { + builder = builder.with_measurement_order(order); + } + + Ok(MemStabSim { + mnm: builder.build(), + }) + } +} diff --git a/crates/pecos-qec/tests/mem_stab_tests.rs b/crates/pecos-qec/tests/mem_stab_tests.rs new file mode 100644 index 000000000..8a8b7e167 --- /dev/null +++ b/crates/pecos-qec/tests/mem_stab_tests.rs @@ -0,0 +1,142 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Integration tests for `MemStabSim`. +//! +//! Parity: `MemStabSim` must produce identical raw-measurement shots to the raw +//! `DagFaultAnalyzer` + `MemBuilder` + `MeasurementNoiseModel` pipeline given equal +//! inputs and seeds. + +use pecos_qec::fault_tolerance::dem_builder::{MemBuilder, NoiseConfig}; +use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; +use pecos_qec::mem_stab::{MemStabError, MemStabSim}; +use pecos_quantum::DagCircuit; +use rand::SeedableRng; +use rand::rngs::SmallRng; + +fn repetition_code_circuit() -> DagCircuit { + let mut dag = DagCircuit::new(); + dag.pz(&[3]); + dag.pz(&[4]); + dag.cx(&[(0, 3)]); + dag.cx(&[(1, 3)]); + dag.cx(&[(1, 4)]); + dag.cx(&[(2, 4)]); + dag.mz(&[3]); + dag.mz(&[4]); + dag +} + +#[test] +fn builder_rejects_missing_circuit() { + let err = MemStabSim::builder().build().unwrap_err(); + assert!(matches!(err, MemStabError::MissingCircuit)); +} + +#[test] +fn zero_noise_produces_zero_mechanisms() { + let sim = MemStabSim::builder() + .circuit(repetition_code_circuit()) + .noise(NoiseConfig::uniform(0.0)) + .build() + .unwrap(); + + assert_eq!(sim.num_mechanisms(), 0); + assert_eq!(sim.num_measurements(), 2); +} + +#[test] +fn parity_with_raw_pipeline() { + let noise = NoiseConfig::uniform(0.01); + let shots = 512; + let seed = 0xFEED_FACE_u64; + + // Path 1: MemStabSim. + let sim = MemStabSim::builder() + .circuit(repetition_code_circuit()) + .noise(noise) + .build() + .unwrap(); + let mut rng1 = SmallRng::seed_from_u64(seed); + let batch1 = sim.sample_batch(shots, &mut rng1); + + // Path 2: raw pipeline, identical inputs + seed. + let dag = repetition_code_circuit(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence_map = analyzer.build_influence_map(); + let mnm = MemBuilder::new(&influence_map) + .with_noise(noise.p1, noise.p2, noise.p_meas, noise.p_init) + .build(); + let mut rng2 = SmallRng::seed_from_u64(seed); + let mut batch2 = Vec::with_capacity(shots); + let mut buf = vec![false; mnm.num_measurements]; + for _ in 0..shots { + mnm.sample_into(&mut buf, &mut rng2); + batch2.push(buf.clone()); + } + + assert_eq!(batch1, batch2); +} + +#[test] +fn sample_and_sample_batch_agree() { + let sim = MemStabSim::builder() + .circuit(repetition_code_circuit()) + .noise(NoiseConfig::uniform(0.02)) + .build() + .unwrap(); + + let seed = 0xABCD_EF01_u64; + let shots = 32; + + let mut rng_single = SmallRng::seed_from_u64(seed); + let singles: Vec> = (0..shots).map(|_| sim.sample(&mut rng_single)).collect(); + + let mut rng_batch = SmallRng::seed_from_u64(seed); + let batch = sim.sample_batch(shots, &mut rng_batch); + + assert_eq!(singles, batch); +} + +#[test] +fn shot_shape_is_correct() { + let sim = MemStabSim::builder() + .circuit(repetition_code_circuit()) + .noise(NoiseConfig::uniform(0.005)) + .build() + .unwrap(); + + let mut rng = SmallRng::seed_from_u64(11); + let batch = sim.sample_batch(20, &mut rng); + assert_eq!(batch.len(), 20); + for row in &batch { + assert_eq!(row.len(), sim.num_measurements()); + } +} + +#[test] +fn nonzero_noise_yields_some_flips() { + let sim = MemStabSim::builder() + .circuit(repetition_code_circuit()) + .noise(NoiseConfig::uniform(0.1)) + .build() + .unwrap(); + + let mut rng = SmallRng::seed_from_u64(123); + let batch = sim.sample_batch(1000, &mut rng); + + let total_flips: usize = batch + .iter() + .map(|row| row.iter().filter(|&&b| b).count()) + .sum(); + assert!(total_flips > 0); +} From 8eb2e0df4e0fc2a1208cf3f5f5f28d57ddd4deda Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 11 Apr 2026 21:11:34 -0600 Subject: [PATCH 008/125] Propose sample_stab batch orchestration sibling to sim() --- design/stab_sample_orchestration.md | 164 ++++++++++++++++++++++++++++ 1 file changed, 164 insertions(+) create mode 100644 design/stab_sample_orchestration.md diff --git a/design/stab_sample_orchestration.md b/design/stab_sample_orchestration.md new file mode 100644 index 000000000..b5adb346a --- /dev/null +++ b/design/stab_sample_orchestration.md @@ -0,0 +1,164 @@ +# `sample_stab` -- Batch Orchestration for Static Stabilizer Sampling + +Status: draft / proposal +Pairs with: `design/qec_sim_literature.md`, `design/dem_stab_sim_skeleton.md` +Date: 2026-04-11 + +## Problem + +PECOS already has the two batch primitives we need: + +- `DemStabSim` (wraps `DemSampler`) -- samples detector + observable flips. +- `MemStabSim` (wraps `MeasurementNoiseModel`) -- samples raw measurement outcomes. + +Both expose `sample_batch(N, rng)` that computes the error mechanism table **once** and then draws N shots in a tight loop. `DemSampler` additionally has rayon-parallel fast paths (`sample_statistics`, `sample_statistics_parallel`) that scale across workers. + +The current main simulation entry, `sim()` in `pecos-engines`, is built on `MonteCarloEngine`: a per-shot classical-engine loop. Wrapping `DemStabSim` / `MemStabSim` behind the `QuantumEngine` streaming trait (the Path A record-and-replay idea in `dem_stab_sim_skeleton.md`) **throws away the batch win**: we would compute the mechanism table once and then re-enter the classical shot loop N times instead of calling `sample_batch(N)` once. + +That is not the right shape for the workload this is built for: + +- Circuits are **static** (no classical feed-forward / conditionals / loops). +- Noise is **Pauli-family** (depolarizing, per-location, later Pauli-Lindblad, later channel-lowered). +- The user wants **many shots, fast**, for threshold estimation / memory experiments / decoder benchmarking. + +## Decision + +Build a separate orchestration entry point, sibling to `sim()`, that preserves batch semantics end-to-end: + +```rust +pub fn sample_stab(dag: DagCircuit) -> StabSampleBuilder +``` + +This mirrors how `pecos-neo` sits next to `sim()` with its own `sim_neo()` entry: each orchestration is honest about the computational model it serves. `sim()` = per-shot classical-control Monte Carlo. `sample_stab()` = one-shot compile + batch sample. + +No retrofit of `MonteCarloEngine`. No record-and-replay through `QuantumEngine`. A clean, separate path. + +## Builder chain + +```rust +let result = sample_stab(dag) + .noise(NoiseConfig::uniform(1e-3)) + .detectors(detectors) // optional -> DEM path + .observables(observables) // optional -> DEM path + .include_raw_measurements(true) // opt-in; default false + .shots(100_000) + .workers(8) // rayon; default 1 + .seed(42) + .run()?; +``` + +Methods: + +- `.noise(NoiseConfig)` -- uniform depolarizing rates. Future: accept any type implementing a `DemStabNoiseModel` trait (see `dem_stab_sim_skeleton.md`). +- `.detectors(Vec)` / `.observables(Vec)` -- if either is set, take the DEM path; otherwise take the MEM path. +- `.include_raw_measurements(bool)` -- always available in MEM path; additionally toggleable in DEM path (carries extra cost). +- `.shots(n)` -- required. +- `.workers(n)` -- rayon worker count. `workers(0)` or omitted -> single-threaded. `workers(None)` / helper `.auto_workers()` -> `available_parallelism`. +- `.seed(u64)` -- master seed; split deterministically across workers. +- `.run()` -- consumes the builder, runs, returns `StabSampleResult`. + +## Dispatch rule + +``` +if detectors.is_empty() && observables.is_empty(): + use MemStabSim -> raw measurement outcomes only. +else: + use DemStabSim -> detector + observable flips (+ optionally raw measurements). +``` + +The user picks by what they register, not by naming a backend. This reads naturally and removes a spurious choice. + +## Result type + +```rust +pub struct StabSampleResult { + /// Per-shot detector flip vectors. Present when detectors were registered. + pub detector_flips: Option>>, + /// Per-shot observable flip vectors. Present when observables were registered. + pub observable_flips: Option>>, + /// Per-shot raw measurement outcomes. Always present in MEM path; + /// present in DEM path iff `.include_raw_measurements(true)`. + pub raw_measurements: Option>>, + /// Metadata for reproducibility / debugging. + pub num_shots: usize, + pub num_mechanisms: usize, + pub seed: u64, +} +``` + +Follow-up helpers (optional, add as the need shows up): +- `.logical_error_rate(observable_id: usize) -> f64` +- `.detector_rates() -> Vec` +- `.to_shot_vec(...) -> ShotVec` for compat with consumers that expect the engines' shot format. + +## Static-only guarantee + +For v1 the input is `DagCircuit`. A `DagCircuit` is a pure gate graph -- it has no conditional-gate opcode, no classical predicate, no loop construct. So the type itself is the static guarantee; no extra traversal or rejection check is needed in v1. + +When v2 adds program-IR lowering (QASM / QIS / HUGR / PHIR -> DagCircuit), the lowering layer does the static check: reject on any classical predicate, classically-controlled gate, or loop that depends on measurement outcomes. Unconditional loops are fine and get unrolled. + +This keeps v1 honest (no pretend-check on a type that can't contain feedback) and v2 honest (check where it actually matters). + +## Parallelism + +Shots are embarrassingly parallel. Two options: + +1. **Leverage the existing `DemSampler::sample_statistics_parallel`.** Already there, already tested. For DEM path this is the single-call fast path. Downside: returns aggregated statistics rather than per-shot bit vectors. +2. **Roll our own rayon split.** Chunk N shots by worker count; each worker gets a seeded RNG split (e.g. `seed ^ worker_idx` or `SplitMix64`). Each worker loops `sample_into_packed` locally. Merge. + +Grug recommend: DEM path -> default to `sample_statistics_parallel` when the user asks only for *aggregate* outputs (rates, logical-error counts). When the user asks for per-shot bit vectors, fall back to rolled-rayon. MEM path -> rolled-rayon (MNM does not have a native parallel path yet; if it becomes a bottleneck, add one). + +Seeding: master seed -> `PecosRng::seed_from_u64(seed)`; split to `workers` child seeds via a deterministic mixer (`SplitMix64`, `seed_from_u64(worker_id)`, whichever matches PECOS convention). Reproducibility means same `(seed, workers, shots)` returns the same bytes. + +## Where it lives + +- Module: `crates/pecos-qec/src/sample.rs`. +- Re-export: `pecos-qec/src/lib.rs` -> `pub use sample::{sample_stab, StabSampleBuilder, StabSampleResult, StabSampleError};`. +- Metacrate: `pecos::sample_stab` via existing pecos-qec re-export path. + +Python bindings in `pecos-rslib` follow later (v1b / v2), once the Rust API is stable. + +## Relationship to `DemStabSim` / `MemStabSim` + +`sample_stab()` is the **user-facing** orchestration. It is implemented on top of `DemStabSim` / `MemStabSim` without giving up direct access to them. + +Power users keep the lower-level APIs: + +```rust +let sim = DemStabSim::builder().circuit(dag).noise(n).detectors(d).build()?; +let mut rng = SmallRng::seed_from_u64(seed); +let batch = sim.sample_batch(n_shots, &mut rng); +// ... introspect sim.sampler(), export DEM, etc. +``` + +`sample_stab` is for "give me shots, now"; the typed sims are for "I need the sampler object for something else". + +## What this deliberately is not + +- Not an extension of `MonteCarloEngine`. Per-shot streaming is not the right fit and forcing it throws away the batch primitive. +- Not a replacement for `sim()`. Classical control + adaptive programs still go through `sim()` with `sparse_stab` + `pecos-neo` noise. Two entries, two computational models. +- Not a Stim rewrite. Naming is honest: "sample a stabilizer circuit statically with depolarizing-family noise". Stim's workflow is inspiration only; the entry point is PECOS-shaped. +- Not an abstraction-first design. If a higher layer above `sample_stab()` and `sim()` turns out to be useful later, it earns that place once concrete duplication shows up. Not before. + +## v1 deliverables + +1. `crates/pecos-qec/src/sample.rs`: + - `StabSampleBuilder` + chain. + - `StabSampleResult`. + - `StabSampleError` (e.g. missing shots, missing noise, builder misuse). + - Dispatch logic: DEM vs MEM on detector/observable presence. + - Rayon parallel shot split; deterministic per-worker seed. +2. Re-exports in `pecos-qec/src/lib.rs`. +3. Integration test: distance-3 repetition code, 10k shots, both DEM and MEM paths, assert logical-error rate sits within binomial CI around the analytic expectation. +4. Doctest on the module header example. +5. Clippy clean. + +## v2+ ideas (not blocking v1) + +- Accept program IRs (QASM / QIS / HUGR / PHIR) with static-check + lowering to `DagCircuit`. +- Accept `TickCircuit` directly. +- Streamed output API (`stream_batches(chunk_size)`). +- Richer result type: `StabSampleResult::logical_error_rate(observable)`, `detector_rates()`, `export_dem()`. +- PyO3 bindings for `sample_stab` in `pecos-rslib`; Python helper `pecos.sample_stab(dag, noise=..., detectors=..., shots=...)`. +- Noise-model trait hierarchy (see `dem_stab_sim_skeleton.md`: `Uniform`, `PerLocation`, `PauliLindblad`, `FromChannel`, eventually `FromLindblad`). +- GPU batch sampler (wgpu) once CPU numbers motivate it. From c66d3c3655136eae89f95a109311fd4c47f2a713 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 11 Apr 2026 21:22:02 -0600 Subject: [PATCH 009/125] Revise sample_stab proposal: pecos.sampling.stab under X4 catalog model - Rename user-facing entry: sample_stab() -> pecos.sampling.stab(). - Document X4 (top-level sim()/sim_neo() + sampling.* catalog) with rejected alternatives X1-X3 spelled out. - Catalog as aliases-not-rivals: sampling.monte_carlo ~ sim, sampling.neo ~ sim_neo, sampling.stab new. - Establish graduation rule: submodule entry -> top-level shortcut only when load-bearing. - Reject 'orchestrator as top-level concept' with reasoning. - Pick .sampling(...) over .orchestration(...) as builder verb: sampling strategy varies, orchestrator is singular. - Mark Path A (QuantumEngine record-and-replay) superseded in skeleton doc. --- design/dem_stab_sim_skeleton.md | 24 ++++- design/stab_sample_orchestration.md | 147 +++++++++++++++++++++++----- 2 files changed, 144 insertions(+), 27 deletions(-) diff --git a/design/dem_stab_sim_skeleton.md b/design/dem_stab_sim_skeleton.md index e857aa848..b5098fb60 100644 --- a/design/dem_stab_sim_skeleton.md +++ b/design/dem_stab_sim_skeleton.md @@ -1,12 +1,26 @@ # DemStabSim Module Skeleton -Status: draft / skeleton -Target crate: `pecos-simulators` (parent) + engine integration in `pecos-engines` -Pairs with: `design/qec_sim_literature.md` (rationale, literature, build order) +Status: partially superseded (2026-04-11). See **`design/stab_sample_orchestration.md`**. +Target crate: `pecos-qec` (pure-sim types) + TBD (engine integration deferred) +Pairs with: `design/qec_sim_literature.md`, `design/stab_sample_orchestration.md` -## Goals in one paragraph +## Current state -Make the existing `pecos-qec::fault_tolerance::dem_builder` pipeline (DagFaultAnalyzer -> DemBuilder / DemSamplerBuilder) selectable through `sim(program).quantum(dem_stab()).noise(...)` as a first-class quantum backend. It behaves as "Clifford + depolarizing-family noise, sampled via precomputed fault influence". Non-adaptive circuits only. No Stim dependency. +**Superseded parts:** +- Original plan: wrap `DemStabSim` behind `sim().quantum(dem_stab())` via a `QuantumEngine` record-and-replay impl (Path A). +- Replaced by: dedicated batch orchestration `pecos::sampling::stab(dag)` that preserves `sample_batch(N)` semantics end-to-end. Path A is rejected -- wrapping a batch primitive behind a per-shot streaming trait throws away the batch win. See `design/stab_sample_orchestration.md` for the new design. + +**Still current:** +- `DemStabSim` / `MemStabSim` pure-sim types and their crate home in `pecos-qec`. +- Noise trait hierarchy sketch (`Uniform`, `PerLocation`, `PauliLindblad`, `FromChannel`, `FromLindblad`). +- Rejection semantics for non-Clifford / adaptive circuits. + +## Goals in one paragraph (revised) + +Make the existing `pecos-qec::fault_tolerance::dem_builder` pipeline usable via two surfaces: +(1) typed pure-sim objects `DemStabSim` / `MemStabSim` (already shipped v0) for direct batch sampling and sampler introspection, +(2) a user-facing orchestration entry `pecos::sampling::stab(dag)` (proposed in `stab_sample_orchestration.md`) that does compile + batch-sample in one call. +Non-adaptive circuits only. No Stim dependency. ## Crate layout diff --git a/design/stab_sample_orchestration.md b/design/stab_sample_orchestration.md index b5adb346a..f96e20879 100644 --- a/design/stab_sample_orchestration.md +++ b/design/stab_sample_orchestration.md @@ -1,8 +1,8 @@ -# `sample_stab` -- Batch Orchestration for Static Stabilizer Sampling +# `pecos.sampling.stab` -- Batch Orchestration for Static Stabilizer Sampling Status: draft / proposal Pairs with: `design/qec_sim_literature.md`, `design/dem_stab_sim_skeleton.md` -Date: 2026-04-11 +Date: 2026-04-11 (revised same day) ## Problem @@ -21,22 +21,91 @@ That is not the right shape for the workload this is built for: - Noise is **Pauli-family** (depolarizing, per-location, later Pauli-Lindblad, later channel-lowered). - The user wants **many shots, fast**, for threshold estimation / memory experiments / decoder benchmarking. +## API architecture: top-level `sim()` plus `sampling.*` catalog + +Four options were considered: + +- **X1 -- single magic top-level.** `sim(anything)` dispatches internally. Rejected: magic hurts predictability. +- **X2 -- flat method-named top-level.** `monte_carlo()`, `dem_sampling()`, `subset_sampling()`, `importance_sampling()`. Rejected: puts "which method fits my problem" on the user; leaks implementation vocabulary. +- **X3 -- flat intent-named top-level.** `sim()`, `sample()`, `rare_events()`. Rejected: vague naming, multiple top entries still. +- **X4 -- one beginner hook + grouped submodule.** Chosen. + +**X4 in one line.** Keep `sim()` and `sim_neo()` as top-level shortcuts for the two most-used strategies; expose the full sampling catalog under a grouping module `pecos.sampling.*` that is IDE-tab-discoverable. + +### Why X4 wins + +- `sim()` is PECOS's brand entry. Breaking it buys nothing. +- Power users get honest explicit access under a grouping noun that tells the truth: these are **sampling strategies**, not "the sim function and its rivals". +- Submodule invites future entries (`sampling.matchgate`, `sampling.decision_diagram`, ...) without cluttering top-level namespace each time. +- Uses user-language word ("sampling"), not implementation-language word ("orchestrator"). + +### Two ways to call the same thing (aliases, not duplicates) + +`sim()` and `sim_neo()` stay top-level as shortcuts. Inside the catalog, the same strategies are available as re-exports -- one implementation, two paths to it: + +| User types | Resolves to | +|---|---| +| `pecos.sim(prog)` | monte-carlo over classical-engine loop | +| `pecos.sampling.monte_carlo(prog)` | **same** code as `sim(prog)` (re-export) | +| `pecos.sim_neo(input)` | pecos-neo tool-framework shot loop | +| `pecos.sampling.neo(input)` | **same** code as `sim_neo(input)` (re-export) | +| `pecos.sampling.stab(dag)` | **new** -- batch DEM/MNM one-shot sample | +| `pecos.sampling.subset(...)` | future | +| `pecos.sampling.importance(...)` | future | + +Not rival entry points. Same implementations, two surfaces: friendly shortcut + explicit catalog. + +### Graduation rule + +A catalog entry graduates to a top-level shortcut only when it's load-bearing enough that users hit it constantly. Current bar is set by `sim` (monte carlo) and `sim_neo` (adaptive / composable noise). If `sampling.stab` becomes as common in a year, promote to `sample_stab()` top-level then. Until it earns promotion, the catalog entry is enough. + +### Why not promote "orchestrator" to the top-level concept + +Grug considered making orchestration the unifying abstraction: `pecos::orchestrator::monte_carlo()`, `pecos::orchestrator::neo()`, `pecos::orchestrator::batch()`. Rejected: + +1. The three orchestrators are **genuinely different shapes**, not three instances of one pattern. MonteCarloEngine (per-shot, classical-driven, streaming), pecos-neo tool framework (per-shot, ECS, rayon, adaptive), batch sampler (no shot loop at all). Unifying under one trait becomes a tagged union with mostly-optional methods -- the abstraction doesn't save code, it just moves the switch statement. +2. **Zero duplication evidence** between pecos-neo and the proposed batch path. Let concrete duplication name the abstraction, not prediction. +3. **"Orchestrator" is implementation-language.** Users ask "how do I get shots" and "what sampling strategy fits my problem", not "which orchestrator runs it". Top-level entries stay named by behavior. + +If a real orchestrator abstraction earns its place later (concrete duplication shows up, a user asks to swap orchestrators), that's the moment to extract it -- not now. + +## `sampling` vs `orchestration` as a builder verb + +When a sampling strategy needs to be selected *inside* an existing entry (e.g. `sim_neo(prog).(strategy)`), the verb is `.sampling(...)`, not `.orchestration(...)`: + +```rust +sim_neo(prog) + .sampling(sampling::monte_carlo()) // default + .sampling(sampling::importance(config)) // alt + .sampling(sampling::subset(config)) // alt + .run() +``` + +Reasoning: + +- Inside `sim_neo`, the **orchestrator is singular** (pecos-neo's tool framework). What varies per call is the **sampling strategy** that plugs into it. The verb names the axis that changes. +- `sampling` is user-language (statistical choice); `orchestration` is implementation-language (execution mechanism). Users pick statistical strategy. +- Matches the catalog noun `pecos.sampling.*`. Same word for the same concept at both call sites. +- Reserves `.orchestrator(...)` for the day (if ever) when swapping orchestrators is a user-visible axis. + ## Decision -Build a separate orchestration entry point, sibling to `sim()`, that preserves batch semantics end-to-end: +Build a separate orchestration entry, sibling to `sim()`, living inside the `sampling` catalog: ```rust -pub fn sample_stab(dag: DagCircuit) -> StabSampleBuilder +pub fn stab(dag: DagCircuit) -> sampling::stab::Builder ``` -This mirrors how `pecos-neo` sits next to `sim()` with its own `sim_neo()` entry: each orchestration is honest about the computational model it serves. `sim()` = per-shot classical-control Monte Carlo. `sample_stab()` = one-shot compile + batch sample. +Called as `pecos::sampling::stab(dag).noise(...).shots(...).run()`. `sim()` / `sim_neo()` are untouched; they become catalog entries as re-exports (`sampling::monte_carlo`, `sampling::neo`). -No retrofit of `MonteCarloEngine`. No record-and-replay through `QuantumEngine`. A clean, separate path. +No retrofit of `MonteCarloEngine`. No record-and-replay through `QuantumEngine`. A clean, separate path that preserves batch semantics end-to-end. ## Builder chain ```rust -let result = sample_stab(dag) +use pecos_qec::sampling; + +let result = sampling::stab(dag) .noise(NoiseConfig::uniform(1e-3)) .detectors(detectors) // optional -> DEM path .observables(observables) // optional -> DEM path @@ -53,9 +122,9 @@ Methods: - `.detectors(Vec)` / `.observables(Vec)` -- if either is set, take the DEM path; otherwise take the MEM path. - `.include_raw_measurements(bool)` -- always available in MEM path; additionally toggleable in DEM path (carries extra cost). - `.shots(n)` -- required. -- `.workers(n)` -- rayon worker count. `workers(0)` or omitted -> single-threaded. `workers(None)` / helper `.auto_workers()` -> `available_parallelism`. +- `.workers(n)` -- rayon worker count. `workers(0)` or omitted -> single-threaded. Helper `.auto_workers()` -> `available_parallelism`. - `.seed(u64)` -- master seed; split deterministically across workers. -- `.run()` -- consumes the builder, runs, returns `StabSampleResult`. +- `.run()` -- consumes the builder, runs, returns `SampleResult`. ## Dispatch rule @@ -71,7 +140,8 @@ The user picks by what they register, not by naming a backend. This reads natura ## Result type ```rust -pub struct StabSampleResult { +// pecos_qec::sampling::stab::SampleResult +pub struct SampleResult { /// Per-shot detector flip vectors. Present when detectors were registered. pub detector_flips: Option>>, /// Per-shot observable flip vectors. Present when observables were registered. @@ -112,40 +182,65 @@ Seeding: master seed -> `PecosRng::seed_from_u64(seed)`; split to `workers` chil ## Where it lives -- Module: `crates/pecos-qec/src/sample.rs`. -- Re-export: `pecos-qec/src/lib.rs` -> `pub use sample::{sample_stab, StabSampleBuilder, StabSampleResult, StabSampleError};`. -- Metacrate: `pecos::sample_stab` via existing pecos-qec re-export path. +Module layout follows PECOS convention (`foo.rs` + sibling `foo/` directory, no `mod.rs`): + +``` +crates/pecos-qec/src/sampling.rs -- parent module, catalog root +crates/pecos-qec/src/sampling/stab.rs -- stab strategy (this work) +crates/pecos-qec/src/sampling/neo.rs -- re-export of sim_neo() (future) +crates/pecos-qec/src/sampling/monte_carlo.rs -- re-export of sim() (future) +``` + +Public names: + +- `pecos_qec::sampling::stab::stab(dag) -> Builder` -- entry free function. + Actually cleaner: `pecos_qec::sampling::stab(dag) -> stab::Builder` (the module name doubles as the function when there's one primary constructor). Implemented as: + ```rust + // in sampling.rs + pub mod stab; + pub use stab::sample as stab; // or inline: pub fn stab(dag) -> ... + ``` + Bikeshed -- decide at implementation time. +- `pecos_qec::sampling::stab::Builder` +- `pecos_qec::sampling::stab::SampleResult` +- `pecos_qec::sampling::stab::BuilderError` + +Metacrate re-export: `pecos::sampling::stab` via existing `pecos-qec` re-export path. Python bindings in `pecos-rslib` follow later (v1b / v2), once the Rust API is stable. ## Relationship to `DemStabSim` / `MemStabSim` -`sample_stab()` is the **user-facing** orchestration. It is implemented on top of `DemStabSim` / `MemStabSim` without giving up direct access to them. +`sampling::stab()` is the **user-facing** orchestration. It is implemented on top of `DemStabSim` / `MemStabSim` without giving up direct access to them. Power users keep the lower-level APIs: ```rust +use pecos_qec::DemStabSim; + let sim = DemStabSim::builder().circuit(dag).noise(n).detectors(d).build()?; let mut rng = SmallRng::seed_from_u64(seed); let batch = sim.sample_batch(n_shots, &mut rng); // ... introspect sim.sampler(), export DEM, etc. ``` -`sample_stab` is for "give me shots, now"; the typed sims are for "I need the sampler object for something else". +`sampling::stab` is for "give me shots, now"; the typed sims are for "I need the sampler object for something else". ## What this deliberately is not - Not an extension of `MonteCarloEngine`. Per-shot streaming is not the right fit and forcing it throws away the batch primitive. - Not a replacement for `sim()`. Classical control + adaptive programs still go through `sim()` with `sparse_stab` + `pecos-neo` noise. Two entries, two computational models. - Not a Stim rewrite. Naming is honest: "sample a stabilizer circuit statically with depolarizing-family noise". Stim's workflow is inspiration only; the entry point is PECOS-shaped. -- Not an abstraction-first design. If a higher layer above `sample_stab()` and `sim()` turns out to be useful later, it earns that place once concrete duplication shows up. Not before. +- Not an abstraction-first design. If a higher layer above `sampling::stab()` and `sim()` turns out to be useful later, it earns that place once concrete duplication shows up. Not before. +- Not a promotion of "orchestrator" to a top-level concept. See the X4 reasoning above. ## v1 deliverables -1. `crates/pecos-qec/src/sample.rs`: - - `StabSampleBuilder` + chain. - - `StabSampleResult`. - - `StabSampleError` (e.g. missing shots, missing noise, builder misuse). +1. `crates/pecos-qec/src/sampling.rs` + `crates/pecos-qec/src/sampling/stab.rs`: + - Free function `stab(dag) -> Builder`. + - `Builder` + chain. + - `SampleResult`. + - `BuilderError` (e.g. missing shots, missing noise, builder misuse). - Dispatch logic: DEM vs MEM on detector/observable presence. - Rayon parallel shot split; deterministic per-worker seed. 2. Re-exports in `pecos-qec/src/lib.rs`. @@ -155,10 +250,18 @@ let batch = sim.sample_batch(n_shots, &mut rng); ## v2+ ideas (not blocking v1) +- **Catalog completeness**: add `sampling::monte_carlo` (alias to `sim()`) and `sampling::neo` (alias to `sim_neo()`) so the `pecos.sampling.*` namespace is a full catalog from day one. - Accept program IRs (QASM / QIS / HUGR / PHIR) with static-check + lowering to `DagCircuit`. - Accept `TickCircuit` directly. - Streamed output API (`stream_batches(chunk_size)`). -- Richer result type: `StabSampleResult::logical_error_rate(observable)`, `detector_rates()`, `export_dem()`. -- PyO3 bindings for `sample_stab` in `pecos-rslib`; Python helper `pecos.sample_stab(dag, noise=..., detectors=..., shots=...)`. +- Richer result type: `SampleResult::logical_error_rate(observable)`, `detector_rates()`, `export_dem()`. +- PyO3 bindings for `sampling::stab` in `pecos-rslib`; Python helper `pecos.sampling.stab(dag, noise=..., detectors=..., shots=...)`. - Noise-model trait hierarchy (see `dem_stab_sim_skeleton.md`: `Uniform`, `PerLocation`, `PauliLindblad`, `FromChannel`, eventually `FromLindblad`). - GPU batch sampler (wgpu) once CPU numbers motivate it. +- Future sampling strategies: `sampling::subset`, `sampling::importance`, `sampling::rare_events`, ... each as its own submodule under `sampling/`. + +## Open questions + +- [ ] Exact free-function name: `sampling::stab(dag)` vs `sampling::stab::sample(dag)` vs `sampling::stab::new(dag)`. Decide at implementation. Grug lean `sampling::stab(dag)` -- one token, reads cleanly. +- [ ] Where does `sampling::neo` live? In `pecos-qec/src/sampling/neo.rs` as a re-export of the `pecos-neo` crate, or should `pecos-neo` itself expose the module path? Defer until `sampling::stab` lands; decide then. +- [ ] `sampling::monte_carlo` as an alias of `sim()` implies a dep from `pecos-qec` -> `pecos-engines`. Currently it's the other way. If keeping `pecos-qec` free of `pecos-engines`, the alias lives in the metacrate `pecos` instead. Likely the right answer. From e02d881c1e342540cf3bbdecbc4d15b9ef2124da Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 12 Apr 2026 23:40:51 -0600 Subject: [PATCH 010/125] Add Lindblad/trajectory sim skeleton + refine literature #7 --- design/lindblad_sim_skeleton.md | 374 ++++++++++++++++++++++++++++++++ design/qec_sim_literature.md | 19 +- 2 files changed, 390 insertions(+), 3 deletions(-) create mode 100644 design/lindblad_sim_skeleton.md diff --git a/design/lindblad_sim_skeleton.md b/design/lindblad_sim_skeleton.md new file mode 100644 index 000000000..b84b92b2f --- /dev/null +++ b/design/lindblad_sim_skeleton.md @@ -0,0 +1,374 @@ +# Lindblad / Trajectory Simulator -- Module Skeleton + +Status: draft (2026-04-12) +Target crate: new `pecos-lindblad` (or module inside `pecos-neo`; decision below) +Pairs with: `design/qec_sim_literature.md` (#7), `design/dem_stab_sim_skeleton.md`, `design/stab_sample_orchestration.md` + +## Goals in one paragraph + +Add a continuous-time open-system simulator to PECOS that bridges device physics +to the existing DEM / stabilizer pipeline via a **gate + duration -> effective +Pauli-Lindblad rates** lowering (arXiv:2502.03462). Offer two surfaces: +(a) `Gate -> Magnus-on-superoperator -> PauliLindbladModel -> DemStabSim` +for fast Pauli-twirled noise used in QEC threshold sweeps, and +(b) a direct `LindbladTrajectorySim` (MCWF / quantum jumps) for small circuits +(<= 10 qubits) to validate the twirl and to expose coherent / non-Pauli effects +that a twirled DEM misses (arXiv:2402.16727, 2510.23797). +Keep scope minimal: adaptive Dormand-Prince solver, dense `faer::Mat`, rayon +fan-out on trajectories. No MPS, no Krylov, no GPU on v1. + +## Why now (one-liner per literature scout) + +Nobody in the mature Python/Julia stack (QuTiP, Dynamiqs, QuantumToolbox.jl) +exposes the `Lindbladian + gate_duration -> PauliLindbladModel` API. This is +the wedge. Everything else is the 80/20 ODE plumbing. + +## Two-path architecture + +``` + +----------------------+ +Gate { H_ideal, H_err, c_ops, duration } | PauliLindbladModel | + | | { supports, rates }| + | Magnus / Dyson on superoperator +----------+-----------+ + | (arXiv:2502.03462) | + v | feeds +(a) Pauli-twirled -> PauliLindbladModel -------------------> DemStabSim + (fast, threshold sweeps) + +Gate { ... } + initial |psi> + | + | MCWF / quantum jumps (Daley 2014) + | dense n x n, adaptive RK (Dormand-Prince) + v +(b) LindbladTrajectorySim ------> syndrome samples -> learned DEM + (captures coherent + hyperedges twirl misses) +``` + +Both paths share `Gate`, `Lindbladian`, and `PauliBasis` primitives. Path (a) +is the MVP and the integration with `DemStabSim`. Path (b) is the reference +validator -- small but honest. + +## Crate placement (decision) + +**Proposal: new crate `crates/pecos-lindblad`** peer of `pecos-neo`, not inside +it. Reasons: + +1. `pecos-neo`'s `NoiseChannel` trait is sample-only (`NoiseResponse` is + a Pauli-injection enum). Lindblad synthesis lowers *to* rates; trajectory + sim lowers *to* a stream of pure-state wavefunctions. Neither fits the + current trait without widening it. Keep trait lean; add a sibling crate + that *feeds* it. +2. Lindblad sim pulls in `faer` + `ode_solvers` (or `diffsol`). `pecos-neo` + today only has `rand`, `rayon`, `smallvec`. Don't fatten the base crate. +3. Clean cut: `pecos-lindblad` produces `PauliLindbladModel` and + `TrajectoryShot`; `pecos-neo` and `pecos-qec::dem_stab` consume them. + +Alternative considered: put behind a feature flag inside `pecos-neo`. +Rejected -- feature flags on numerics crates become build-matrix purgatory. + +## Crate layout + +``` +crates/pecos-lindblad/ + Cargo.toml # faer, ode_solvers (or diffsol), rand, rayon, thiserror + src/ + lib.rs + basis.rs # PauliBasis, PauliString, SparsePauliOp + lindbladian.rs # Lindbladian { H: Matrix, c_ops: Vec } + gate.rs # Gate { ideal: UnitaryRep, H_drive(t), c_ops, duration } + magnus.rs # Magnus/Dyson on superoperator -> effective generator + pauli_twirl.rs # Liouvillian -> diagonal in Pauli basis -> rates + trajectory.rs # MCWF / quantum jumps unraveling (Path b) + solver.rs # thin Dormand-Prince wrapper over faer state + api.rs # public builders: MagnusSynth, TrajectorySim + tests/ + parity_small.rs # symbolic case from arXiv:2502.03462 Appendix C + trajectory_vs_me.rs # mcwf(N) -> rho_avg vs mesolve, within statistical CI + pauli_twirl_roundtrip.rs +``` + +Integration-side additions (kept in owning crates): + +``` +crates/pecos-qec/src/dem_stab.rs + + DemStabNoiseModel impl for pecos_lindblad::PauliLindbladModel +crates/pecos-neo/src/noise/lindblad_derived.rs + + Cached LindbladChannel(table: HashMap<(GateId, OrderedFloat), PauliChannel>) +``` + +## Public surface -- Rust + +### Core types + +```rust +/// Sparse Pauli-basis decomposition (arXiv:2201.09866 generator form). +pub struct PauliLindbladModel { + pub supports: Vec, + pub rates: Vec, // lambda_k >= 0 +} + +impl PauliLindbladModel { + /// p_flip for Pauli k over duration t: (1 - exp(-2 lambda_k t)) / 2. + pub fn flip_probs(&self, t: f64) -> Vec; + + /// Sample one realization over duration t. + pub fn sample(&self, t: f64, rng: &mut impl Rng) -> SparsePauliOp; +} + +/// Time-independent collapse-operator Lindbladian. +/// Time-dependent H is handled on `Gate` via H_drive(t) closure. +pub struct Lindbladian { + pub hamiltonian: FaerMat, // n x n + pub collapse_ops: Vec<(FaerMat, f64)>, // (c_k, gamma_k) +} + +pub struct Gate { + pub label: &'static str, + pub ideal: UnitaryRep, // for sanity-check / inverse + pub drive_hamiltonian: Option FaerMat + Send + Sync>>, + pub static_lindbladian: Lindbladian, // H_err + c_ops during the gate + pub duration: f64, +} +``` + +### Path (a): Magnus synthesis + +```rust +pub struct MagnusSynth { + order: u8, // 1, 2, 3, 4 (paper goes to 4) + twirl: bool, // default true for PauliLindbladModel output + basis: PauliBasis, // sparse by default, up to weight-2 +} + +impl MagnusSynth { + pub fn synthesize(&self, gate: &Gate) -> Result; + + /// Untwirled variant: full Liouville generator (useful for (b) validation). + pub fn synthesize_generator(&self, gate: &Gate) + -> Result, SynthError>; +} + +/// Grug-fallback: numerical integration of the Liouvillian directly, no Magnus. +/// Use as gold standard; slow but unambiguous. +pub fn synthesize_numerical(gate: &Gate, rtol: f64, atol: f64) + -> Result, SynthError>; +``` + +### Path (b): trajectory simulator + +```rust +pub struct TrajectorySim { + initial_state: StateVec, + gate_sequence: Vec, + num_trajectories: usize, + seed: u64, +} + +impl TrajectorySim { + pub fn builder() -> TrajectorySimBuilder { ... } + + pub fn run(&self) -> TrajectoryBatch; // rayon fan-out +} + +pub struct TrajectoryBatch { + pub final_states: Vec, // one per trajectory + pub jump_records: Vec>, // when / which c_op fired + pub measurement_outcomes: Option, +} +``` + +### Glue into DemStabSim + +```rust +// in pecos-qec::dem_stab +impl DemStabNoiseModel for pecos_lindblad::PauliLindbladModel { ... } + +// Usage: +let pl_noise: PauliLindbladModel = MagnusSynth::order(2).synthesize(&gate_cx)?; +let sim = DemStabSim::builder() + .circuit(dag) + .noise(pl_noise) // directly consumed, no conversion layer + .detectors(...) + .observables(...) + .build()?; +``` + +### Glue into pecos-neo (non-DEM stabilizer Monte Carlo) + +For researchers who want realistic noise on a `sparse_stab()` run without the +DEM detour: cache the Magnus output per gate and expose it as a +`NoiseChannel` that injects Pauli samples. + +```rust +// in pecos-neo::noise::lindblad_derived +pub struct LindbladChannel { + // (GateId, duration_ns) -> precomputed PauliLindbladModel + table: HashMap<(GateId, OrderedFloat), PauliLindbladModel>, +} + +impl NoiseChannel for LindbladChannel { + fn apply(&self, event: &NoiseEvent, ctx: &mut NoiseContext, rng: &mut PecosRng) + -> NoiseResponse { + // look up (gate_id, duration) in table; sample Pauli; InjectGates + } +} +``` + +**Pre-req:** `NoiseEvent::AfterGate` must grow a `duration` field (today only +`IdleTime` carries duration). Small, localized change in `pecos-neo/src/noise.rs` +-- flag as first integration PR. Without this the lookup table can't be keyed. + +## Noise-model input hierarchy + +| Input shape | Path to DEM | Who produces it | +|---|---|---| +| Ideal + per-qubit T1/T2 + gate duration | Magnus (1st order enough) | user spec | +| + coherent over-rotation / miscalibration | Magnus (2nd-4th order) | user spec or fit | +| + 2Q ZZ crosstalk | Magnus (closed-form from 2502.03462 Appendix D) | user spec | +| Learned sparse PL from device (PEC) | direct -- already PauliLindbladModel | cycle-benchmarking fit (future `pecos-char` crate?) | +| General CPTP / Choi channel | Pauli-twirl -> rates | `synthesize_numerical` then twirl | + +## Solver choice + +Default: **adaptive Dormand-Prince 5(4)** via `ode_solvers` (nalgebra-native, +simple) or `diffsol` (more features, BDF for stiff). Tolerances `rtol=1e-6`, +`atol=1e-9`. Pack `Complex64` as interleaved `[re, im, re, im, ...]` +`Vec` for solver input (both crates are real-only). + +Magnus integrand evaluation: closed-form first order, trapezoidal second-order +nested, adaptive Gauss-Kronrod for third/fourth order (or punt to +`synthesize_numerical` for order > 2). Grug vote: ship order-2 as default; add +higher orders only when a test case demands. + +## State representation + +Keep density matrix as `faer::Mat` of size `n x n` (QuTiP's +`matrix_form` trick). Apply `-i[H, rho] + sum_k (c_k rho c_k^dag - +(1/2){c_k^dag c_k, rho})` directly. Avoid materializing the `n^2 x n^2` +superoperator except for Pauli-transfer-matrix extraction. Crossover to +vectorized superop at `n <= 4 qubits` via a cfg-gated fast path; do not +implement v1. + +Pauli basis representation: `PauliString` = pair of `BitVec` (x-part, z-part) +plus sign/phase. Sparse storage `Vec<(PauliString, f64)>` for +`PauliLindbladModel`. Up to weight-2 by default; weight-3+ opt-in. + +## Trajectory parallelization + +- `rayon::par_iter` over `0..num_trajectories`. +- Each trajectory gets its own `rand_chacha::ChaCha12Rng` seeded from + `master_seed.wrapping_add(trajectory_idx as u64)`. Deterministic under + parallel execution. +- No GPU on v1. (Dynamiqs-style `vmap+jit` is the future win but requires + wgpu/CUDA ODE integrator -- defer until CPU numbers demand.) + +## Tests (initial) + +1. **Magnus parity vs paper.** Reproduce the amplitude-damping-under-identity + and the cross-resonance CX symbolic rates from arXiv:2502.03462 Appendix C + within `< 1e-10`. Freeze numerical values as test fixtures. +2. **Magnus vs numerical.** For random Lindbladians with `beta/omega_g < 0.1`, + compare `MagnusSynth::order(4)` against `synthesize_numerical` -- should + match within `< 1e-6`. +3. **Magnus out-of-regime detection.** At `beta/omega_g = 1.0`, Magnus order-2 + vs order-4 should diverge; `SynthError::OutOfConvergenceRegime` must fire. +4. **Trajectory vs master equation.** For 1-qubit T1 decay, 10k trajectories + averaged should match `mesolve` output within binomial CI. +5. **Pauli twirl round-trip.** `Liouvillian -> twirl -> Pauli rates -> sample + -> average` must match the diagonal of the twirled generator. +6. **End-to-end DemStabSim glue.** Small rep-code memory experiment: feed + `MagnusSynth` output to `DemStabSim`, compare logical error rate against + the trajectory path (path b) on the same circuit. +7. **Integration regression.** After `NoiseEvent::AfterGate::duration` lands + in `pecos-neo`, add a parity test with `LindbladChannel` vs + `DemStabSim + PauliLindbladModel` on identical circuit. + +## Rejection / validation + +- Non-Hermitian `H_drive`: reject at `Gate` construction. +- Non-CP `c_ops` (gamma_k < 0): reject. Pseudo-Lindblad (arXiv:2306.14876) + opt-in only. +- Magnus convergence check: estimate `||beta|| * duration` vs `||H_ideal||`; + emit warning if > 0.3, error if > 1.0 (tunable). +- Time-ordered integrals of `H_drive(t)`: require user-supplied `Fn(f64)` + plus optional `sample_points` hint; otherwise adaptive. + +## Out of scope for v1 + +- **GPU solver path.** Natural follow-up once CPU numbers are known. +- **MPS / tensor-network Lindblad.** Too far from the wedge. +- **Non-Markovian (Redfield, HEOM) solvers.** Separate design. +- **Stochastic master equation (SME) / diffusive unravelings.** Separate design. +- **Krylov / expm-based propagators.** Default is adaptive RK; add later if + stiffness demands. +- **Magnus as time-stepping integrator.** Different use (arXiv:2407.03576); + here Magnus is for effective-generator synthesis only. +- **Leakage-aware Lindblad.** Needs 3-level model; design separately + (see scout open question on leakage). + +## Open questions + +- [ ] Crate name: `pecos-lindblad` vs `pecos-open-system` vs fold into + `pecos-neo`. Grug prefers `pecos-lindblad` -- says what it is. +- [ ] Magnus order default: 2 (cheap, closed-form) or 4 (paper's highest). + Probably 2; 4 as opt-in for research. +- [ ] Should `PauliLindbladModel` live in `pecos-lindblad` or promoted to + `pecos-qec` so `DemStabSim` can consume it without a dependency flip? + Lean `pecos-qec` -- it's a noise format, not Lindblad-specific. +- [ ] Symbolic vs numerical Appendix-D (ZZ crosstalk) formulae: + can we parse paper's LaTeX / Mathematica output, or transcribe? Manual + transcription of 3-4 closed forms is honest work; skip symbolic + pipelines. +- [ ] Gate-duration data path: does `TickCircuit` today carry per-gate + duration metadata, or is duration attached at noise-lookup time via a + separate `GateDurationTable`? Audit `crates/pecos-circuits`. +- [ ] Seeding semantics for `MagnusSynth` (deterministic, no RNG needed) vs + `TrajectorySim` (per-trajectory seed). Document clearly. + +## Build order + +1. **`pecos-lindblad` crate scaffold** + `PauliBasis` + `Lindbladian` + + `Gate` types. Tests: round-trip Pauli ops, Lindbladian constructor sanity. +2. **`synthesize_numerical`** (gold-standard, slow). One integrator, one pass. + Tests: trajectory-vs-mesolve (test #4) uses this. +3. **`MagnusSynth::order(1)` + `order(2)`** with twirl. Tests: parity vs + `synthesize_numerical` + paper fixtures (tests #1, #2, #5). +4. **Glue into `DemStabSim`** -- implement `DemStabNoiseModel` for + `PauliLindbladModel`. Tests: #6. +5. **`TrajectorySim`** (Path b) -- MCWF, rayon fan-out. Tests: #4 properly, + small rep-code validation run. +6. **`NoiseEvent::AfterGate::duration` + `LindbladChannel`** in `pecos-neo`. + Tests: #7. +7. **Higher-order Magnus (3, 4)** + convergence detection. Tests: #3. + +Stop after step 4 if that's all that's needed for the next research run. +Steps 5-7 unlock honest coherent-error studies but are not on the critical +path for Pauli-noise threshold sweeps. + +## References + +Must-read: +- arXiv:2502.03462 -- Magnus/Dyson Lindblad synthesis (**the algorithm**) +- arXiv:2201.09866 -- sparse Pauli-Lindblad generator form +- arXiv:2311.15408 -- learning sparse PL models +- arXiv:2402.16727 -- when Pauli approximation underestimates QEC failure +- arXiv:2510.23797 -- coherent-error hyperedges missing from twirled DEMs +- arXiv:2407.03576 -- 4th-order commutator-free Magnus (gold-standard cross-check) +- Daley 2014 (Adv. Phys.) -- MCWF review + +Should-read: +- arXiv:2406.08981 -- Bayesian CPTP learning from syndromes +- arXiv:2512.10814 -- decoder-free DEM estimation on Willow +- arXiv:2504.21440 -- QuantumToolbox.jl architecture + +Nice-to-have: +- arXiv:2306.14876 -- pseudo-Lindblad trajectories for non-GKSL +- arXiv:2405.12925 -- Magnus superconvergence (Hamiltonian sim) +- arXiv:2107.10054 -- periodic-Lindblad high-frequency expansion + +Rust crates evaluated: +- `diffsol` (stiff + non-stiff, dense+sparse, nalgebra/faer) +- `ode_solvers` (simpler, nalgebra-native) +- `faer` (fast dense linalg) +- `rand_chacha` (per-trajectory seeding) diff --git a/design/qec_sim_literature.md b/design/qec_sim_literature.md index 833a95d6f..7180a6841 100644 --- a/design/qec_sim_literature.md +++ b/design/qec_sim_literature.md @@ -186,11 +186,13 @@ The DemSampler today operates on a `DagFaultInfluenceMap` produced by circuit-le ### 7. Lindblad / master-equation + quantum-trajectory simulators +**Design doc:** `design/lindblad_sim_skeleton.md` (2026-04-12). + **What it is.** Continuous-time evolution under Lindbladians, optionally unraveled as stochastic quantum trajectories (Monte Carlo wavefunction / quantum jumps). -**Why QEC needs it.** Realistic noise: T1/T2, coherent errors, leakage, crosstalk, cross-resonance dynamics; non-Markovian extensions; studying Pauli-twirl approximation error; modeling syndrome extraction in the analog regime. +**Why QEC needs it.** Realistic noise: T1/T2, coherent errors, leakage, crosstalk, cross-resonance dynamics; non-Markovian extensions; studying Pauli-twirl approximation error; modeling syndrome extraction in the analog regime. **The wedge:** no mainline OSS (QuTiP, Dynamiqs, QuantumToolbox.jl) exposes `Lindbladian + gate_duration -> effective Pauli-Lindblad rates`. arXiv:2502.03462 defines this algorithm (Magnus/Dyson on superoperator, then Pauli-twirl). -**PECOS status.** `pecos-neo` has composable noise channels at the gate/Pauli level, but no continuous-time Lindblad or trajectory solver (TODO: verify). +**PECOS status (audit 2026-04-12).** `exp/pecos-neo/` has sample-only `NoiseChannel` trait (`src/noise.rs:607`); `NoiseResponse` is a Pauli-injection enum. Time only on `NoiseEvent::IdleTime` -- `AfterGate` lacks a `duration` field. No Kraus/CPTP infrastructure, no continuous-time solver. Clean gap. **Seminal refs.** - Dalibard, Castin, Molmer (1992) [MCWF]. @@ -205,7 +207,18 @@ The DemSampler today operates on a `DagFaultInfluenceMap` produced by circuit-le **Newer ref worth tracking.** - Lambert et al., *QuantumToolbox.jl* (2025), arXiv:2504.21440. -- *Efficient Lindblad synthesis for noise model construction*, npj QI 11 (2025), arXiv:2502.03462 -- bridges Lindblad sims to Pauli-noise models (useful for feeding DEM pipelines). +- Malekakhlagh et al., *Efficient Lindblad synthesis for noise model construction*, npj QI 11 (2025), arXiv:2502.03462 -- **key bridge paper**. Magnus-on-superoperator in interaction frame + Pauli-twirl gives diagonal Pauli-Lindblad generator. No public code. Defines the `Gate -> PauliLindbladModel` API PECOS needs. +- Pichler & Zoller et al. / arXiv:2407.03576 -- 4th-order commutator-free Magnus in Liouville space (gold-standard cross-check for effective-generator synthesis). +- arXiv:2402.16727 -- *Pauli approximation can underestimate logical failure rate* for 5-qubit code under realistic Lindblad; warns twirl is not free. +- arXiv:2510.23797 -- coherent DEMs have hyperedges that vanish under Pauli twirl; motivates path (b) trajectory -> learned DEM as validator. +- Daley 2014 (Adv. Phys.) -- canonical MCWF review; no post-2020 replacement. +- arXiv:2306.14876 -- pseudo-Lindblad trajectories for non-GKSL (opt-in, post-v1). + +**Reference implementations (scout 2026-04-12).** +- QuTiP: `mesolve` default `"adams"` (zvode), `mcsolve` uses bisection for jump times. +- Dynamiqs (JAX/GPU): `Tsit5/Dopri5/Dopri8` + `jax.vmap+jit` for trajectory batching -- source of its ~30x dissipative-cat-CNOT speedup. +- QuantumToolbox.jl: `DP5()` default via OrdinaryDiffEq; `EnsembleThreads` for trajectories. Closest architectural template for PECOS. +- None expose `Lindbladian + duration -> Pauli rates`. --- From 4d2bd013fa55bbf45ff914bcb4ee8dd04ae48b93 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 12 Apr 2026 23:48:05 -0600 Subject: [PATCH 011/125] Add Magnus/Pauli-Lindblad algorithm spec + resolve skeleton open questions --- design/lindblad_magnus_algorithm.md | 323 ++++++++++++++++++++++++++++ design/lindblad_sim_skeleton.md | 44 ++-- 2 files changed, 355 insertions(+), 12 deletions(-) create mode 100644 design/lindblad_magnus_algorithm.md diff --git a/design/lindblad_magnus_algorithm.md b/design/lindblad_magnus_algorithm.md new file mode 100644 index 000000000..5e38bc01c --- /dev/null +++ b/design/lindblad_magnus_algorithm.md @@ -0,0 +1,323 @@ +# Algorithm Spec: Lindblad -> Pauli-Lindblad Synthesis + +Status: draft (2026-04-12) -- extracted from scout deep-read. +Pairs with: `design/lindblad_sim_skeleton.md` (uses this as the MagnusSynth kernel). + +**Primary reference.** Malekakhlagh, Seif, Puzzuoli, Govia, van den Berg, +*Efficient Lindblad synthesis for noise model construction*, npj QI 2025, +arXiv:2502.03462v1. Equation numbers below from the v1 HTML. + +**Secondary reference.** van den Berg, Minev, Kandala, Temme, +*Probabilistic error cancellation with sparse Pauli-Lindblad models*, +Nat. Phys. 2023, arXiv:2201.09866 (sparse PL generator + Pauli fidelity). + +**Caveat (scout).** Scout could not run shell / tar-extract the arxiv +source tarball; spec derived from arxiv HTML endpoints. Tables 3-5 and +Appendix D (3/4-qubit ZZ crosstalk) not verbatim -- manual re-scrape +required before Rust transcription. + +--- + +## 1. Inputs & outputs + +**Inputs.** +- Gate Hamiltonian $H_g \in \mathbb{C}^{d\times d}$, $d=2^n$, Hermitian, + time-(quasi-)independent in the rotating frame (paper eq. 6-8). +- Collapse operators $\{L_j\}$ with rates $\beta_j \ge 0$, or GKS matrix + $\beta_{jk}$; optional coherent shifts $\delta_j$. +- Gate duration $\tau_g$ and gate angle $\theta = \omega_g \tau_g$ + (with $\omega_g \in \{\omega_{cz}, \omega_{cx}\}$). +- Pauli basis $\mathcal{K} \subseteq \{I,X,Y,Z\}^{\otimes n}\setminus\{I^{\otimes n}\}$ + (typically weight-1 and weight-2 on device edges). +- Magnus truncation order $N \in \{1,2,3,4\}$. + +**Output.** Rate vector $\{\lambda_k\}_{k\in\mathcal{K}}$ with +$\lambda_k \ge 0$ (non-negativity only guaranteed to the truncation order; +see open questions below). + +**Assumptions.** +- Weak noise: $\beta\tau_g \ll 1$, equivalently $\beta/\omega_g \ll 1$ for + two-qubit gates. Magnus convergence radius. +- Markovianity -- time-local Lindblad master equation. +- $H_g$ time-independent in a convenient frame. Time-dependent $H_g(t)$ + requires $U_g(t) = \mathcal{T}\exp(-i\int H_g(s)\,ds)$ via piecewise + integration (not v1). + +--- + +## 2. Algorithm pseudocode + +``` +INPUT H_g, {L_j, beta_j}, tau_g, K, N +OUTPUT {lambda_k : k in K} + +// Step 1 -- interaction-frame jump operators (paper eq. 6-8) +// P_{jI}(t) = U_g(t)^dag L_j U_g(t) +// L_I(t)(rho) = -i sum_j delta_j [P_{jI}(t), rho] +// + sum_{jk} beta_{jk} ( P_{jI}(t) rho P_{kI}^dag(t) +// - 1/2 { P_{kI}^dag(t) P_{jI}(t), rho } ) +eigendecomp H_g = V D V^dag +U_g(t) = V * diag(exp(-i D t)) * V^dag // pure-phase matrix elements + // in H_g eigenbasis +PjI(t) = U_g(t)^dag * L_j * U_g(t) + +// Step 2 -- Magnus terms (paper eq. 11, 12; App. C for higher orders) +Omega_1 = integrate( L_I(t1), t1 in [0,tau_g] ) +Omega_2 = 0.5 * integrate_double( + comm( L_I(t1), L_I(t2) ), 0 <= t2 <= t1 <= tau_g ) +Omega_3 = (1/6) * integrate_triple( + comm(L_I(t1), comm(L_I(t2), L_I(t3))) + + comm(L_I(t3), comm(L_I(t2), L_I(t1))), 0 <= t3 <= t2 <= t1 <= tau_g ) +Omega_4 = // Blanes-Casas-Oteo-Ros 4-commutator formula (paper App. C) + +// Step 3 -- effective generator (paper eq. 9-10) +L_eff = (1/tau_g) * sum_{n=1..N} Omega_n + +// Step 4 -- Pauli twirl projection +// Twirled generator is diagonal in Pauli basis. +// Diagonal coeff: alpha_b = -(1/d) tr( P_b * L_eff(P_b) ) +// Rates recovered via Walsh-Hadamard on {0,1}^{2n} +// (2201.09866 eq. (1)): +// alpha_b = 2 sum_k lambda_k _sp +// lambda_k = (1/4^n) sum_b (-1)^{_sp} (alpha_b / 2) + +// Step 5 -- Dyson cross-check (paper eq. 13) +// T exp( int L_I ) = I + Omega_1 + Omega_2 + 1/2 Omega_1^2 + O(L_I^3) +// Compare Magnus-truncated channel vs Dyson-truncated channel. +``` + +**Key simplification for constant $H_g$.** Matrix elements of $P_{jI}(t)$ +in the $H_g$ eigenbasis are **pure phases $e^{i(E_a-E_b)t}$**. All Magnus +time integrals become sums of exponentials times polynomials in $t$ -- +integrate **analytically**, no numerical quadrature. This is what makes +closed-form Appendix C results possible. + +**Twirl representation.** $\mathcal{L}_{eff}$ is a $d^2\times d^2$ map +$M_d\to M_d$ in the Pauli transfer matrix (PTM) representation; the +diagonal entries are $-\alpha_b$. Off-diagonals measure residual coherence +and must be small under the weak-noise assumption -- assert +`||off-diagonal|| < tol` as a correctness check. + +--- + +## 3. Closed-form fixtures (Appendix C, Tables 1-2) + +Transcribed for the golden-test path. Index convention: $P_b$ written as +two-letter label `ab` = $P_a \otimes P_b$ on (left, right) qubit; +$i\equiv I$. Rates $\beta_{\downarrow l}, \beta_{\downarrow r}$ are +amplitude-damping on (left, right) qubit; $\beta_\phi$ is pure dephasing. + +### Amplitude damping, Table 1 + +Identity $I_{\tau_g}$: +$$ +\lambda_{ix}=\lambda_{iy}=\tfrac14\beta_{\downarrow r}\tau_g,\quad +\lambda_{xi}=\lambda_{yi}=\tfrac14\beta_{\downarrow l}\tau_g; +\text{ rest } = 0. +$$ + +$CZ_\theta$ ($\theta = \omega_{cz}\tau_g$): +$$ +\lambda_{ix}=\lambda_{iy}=\tfrac{2\theta+\sin 2\theta}{16}\tfrac{\beta_{\downarrow r}}{\omega_{cz}},\quad +\lambda_{xi}=\lambda_{yi}=\tfrac{2\theta+\sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cz}}, +$$ +$$ +\lambda_{xz}=\lambda_{yz}=\tfrac{2\theta-\sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cz}},\quad +\lambda_{zx}=\lambda_{zy}=\tfrac{2\theta-\sin 2\theta}{16}\tfrac{\beta_{\downarrow r}}{\omega_{cz}}. +$$ + +$CX_\theta$ ($\theta = \omega_{cx}\tau_g$): +$$ +\lambda_{ix}=\tfrac{\theta}{4}\tfrac{\beta_{\downarrow r}}{\omega_{cx}},\quad +\lambda_{iy}=\tfrac{12\theta+8\sin 2\theta+\sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}}, +$$ +$$ +\lambda_{iz}=\lambda_{zz}=\tfrac{4\theta-\sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}},\quad +\lambda_{xi}=\lambda_{yi}=\tfrac{2\theta+\sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cx}}, +$$ +$$ +\lambda_{xx}=\lambda_{yx}=\tfrac{2\theta-\sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cx}},\quad +\lambda_{zy}=\tfrac{12\theta-8\sin 2\theta+\sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}}. +$$ + +### Pure dephasing, Table 2 + +Only $\lambda_{iz}, \lambda_{zi}, \lambda_{iy}, \lambda_{zy}, \lambda_{zz}$ +nonzero. + +Identity: $\lambda_{iz}=\tfrac12\beta_{\phi r}\tau_g$, +$\lambda_{zi}=\tfrac12\beta_{\phi l}\tau_g$. + +$CX_\theta$: +$$ +\lambda_{iz}=\tfrac{12\theta+8\sin 2\theta+\sin 4\theta}{64}\tfrac{\beta_{\phi r}}{\omega_{cx}},\quad +\lambda_{zz}=\tfrac{12\theta-8\sin 2\theta+\sin 4\theta}{64}\tfrac{\beta_{\phi r}}{\omega_{cx}}. +$$ + +**Test fixture usage.** Feed $H_{CR}$ and $L\in\{\sigma^-, Z\}$ into the +algorithm; compare against these closed forms to `< 1e-10`. The cases above +are the minimum golden set; extend with CZ pure-dephasing and CX non-left +cases from Tables 1-2 (not transcribed here -- see paper). + +--- + +## 4. Appendix D: multi-qubit ZZ crosstalk + +- **D.7** -- three-qubit ZZ crosstalk. +- **D.8** -- four-qubit ZZ crosstalk. + +**Form.** Plain LaTeX tables; *not* SymPy/Mathematica-parseable. +Each cell is a rational in $\theta$ with $\sin/\cos$ and one +$\beta/\omega$ factor. + +**Effort estimate.** Tables 1-2 alone contain ~20 distinct formulae per +gate column. Extrapolating to D.7+D.8 plus remaining Tables 3-5 yields +roughly **200-300 closed-form $\lambda_k$ formulae total**. Transcribe +into a Rust lookup `(gate_type, pauli_label) -> fn(theta, beta, omega) +-> f64`. One focused afternoon of careful typing + property-test each +entry against the numerical (Magnus-integrated) path. + +--- + +## 5. Sparse Pauli-Lindblad generator (arXiv:2201.09866) + +**Generator.** +$$ +\mathcal{L}(\rho) = \sum_{k\in\mathcal{K}}\lambda_k\bigl(P_k\rho P_k^\dagger - \rho\bigr), +\quad \lambda_k \ge 0. +$$ + +**Pauli fidelity (2201.09866 eq. 1, 2311.15408 eq. 1).** +$$ +f_b = \tfrac{1}{2^n}\operatorname{tr}\bigl(P_b\,\Lambda(P_b)\bigr) + = \exp\!\Bigl(-2\sum_{k\in\mathcal{K}}\lambda_k\,\langle b,k\rangle_{sp}\Bigr). +$$ + +**Symplectic inner product.** Write $P = i^{x\cdot z}X^x Z^z$, +$(x,z)\in\mathbb{F}_2^{2n}$. Then +$$ +\langle b,k\rangle_{sp} = x_b\cdot z_k + z_b\cdot x_k \pmod 2 \in \{0,1\}, +$$ +i.e. `0` if $P_b, P_k$ commute, `1` if they anticommute. Implementation: +bitwise XOR + popcount + `& 1`. `O(n/64)` per pair. + +**Forward sampling over duration $t$.** Each $k$ acts as an independent +single-Pauli channel $(1-p_k)\mathbb{1} + p_k\,P_k\cdot P_k$ with +$$ +p_k = \tfrac12\bigl(1 - e^{-2\lambda_k t}\bigr). +$$ +Per shot: for each $k$, draw Bernoulli($p_k$); if `1`, apply $P_k$. +All $|\mathcal{K}|$ draws independent, $O(|\mathcal{K}|)$ per shot. + +For PEC the signed form $\gamma_k = \text{sign}(\lambda_k)$ would be +tracked; forward QEC simulation uses $\lambda_k \ge 0$ only. + +--- + +## 6. Complexity & data structures + +- **Magnus order $N$.** Each $\Omega_n$: $n$-fold nested commutator of + $d\times d$ matrices + analytic time integral. Dominant matmul cost + $O(N\cdot d^3)$; commutator sum $O(N\cdot M^n)$ with $M$ = number of + jump operators. For $n=2$, $d=4$, $d^3=64$ -- trivial. +- **Pauli basis $\mathcal{K}$.** 1-local = $3n$; 2-local on device edges + $=9|E|$. On 100-qubit heavy-hex ($|E|\approx 140$): ~1560 terms. + $O(n^2)$ worst case. +- **Dense path memory.** State matrix $d\times d$ complex + ($16\,d^2$ bytes). PTM $d^2\times d^2$ ($16\,d^4$ bytes). For 4-qubit + ($d=16$): 0.5 MB -- fine. +- **Sparse path (> 6 qubits).** Represent $\mathcal{L}$ as a list of + `(P_j, P_k, beta_jk)` triples and form $\Omega_n$ symbolically in + Pauli basis via the Pauli-group multiplication table; never + materialize the PTM. +- **Rust types.** `faer::Mat` for small dense path ($d\le 16$). + `SparsePauliOp` (`Vec<(PauliLabel, Complex64)>`) for sparse path. + Commutators via Pauli-group table -- this is where grug gets the + 80/20 win. + +--- + +## 7. Open questions / risks + +- **Positivity of $\lambda_k$.** Magnus-truncated generator is **not + guaranteed** GKS-positive at finite order. Paper dodges via weak-noise + assumption. PECOS policy decision: clip to $\max(0, \lambda_k)$ + (lossy), warn/error on negative, or bump order (expensive). Start with + "warn + clip" and log the truncation residual. + +- **Omega_3 / Omega_4 prefactor verification.** Scout could not extract + Appendix C verbatim through the HTML endpoints. Blanes-Casas-Oteo-Ros + recurrence is the textbook safe default; first implementation must + regression-test against Tables 1-2 closed forms before trusting higher + orders. **Blocking item for order $>2$.** + +- **Time-dependent $H_g(t)$.** Paper assumes quasi-time-independent. + Real pulse shapes (Gaussian, DRAG) break this. Dyson path handles + numerically (time-ordered product); Magnus path needs piecewise + integration. Out of scope v1. + +- **Catastrophic cancellation near $\theta=0$.** Formulae like + $(2\theta-\sin 2\theta)/16$ lose precision at small $\theta$ + ($\approx \theta^3/6$). Rust impl **must** use a Taylor branch for + $|\theta|<\epsilon$. Standard `sinmx` trick; test with + $\theta=10^{-10}$. + +- **PTM off-diagonal residuals.** Weak-noise -> near-diagonal in Pauli + basis. Assert `||off-diagonal|| < tol`; do not silently discard. + +- **Pauli basis $\mathcal{K}$ completeness.** If physical noise generates + a $\lambda_k$ outside $\mathcal{K}$ (e.g. amplified weight-3 ZZ), it is + silently dropped on projection. Log the norm of the projected-away part; + error if above a user-settable threshold. + +--- + +## 8. Implementation phases + +**Phase 1 -- numerical (gold standard).** +Eigendecompose $H_g$, integrate $\Omega_1$ and $\Omega_2$ analytically in +the eigenbasis, assemble $\mathcal{L}_{eff}$ as a PTM, diagonal-read the +$\alpha_b$, Walsh-Hadamard to $\lambda_k$. Test against Table 1 (CX, +amplitude damping, right qubit only). This is the order-2 MagnusSynth +default. + +**Phase 2 -- sparse Pauli-Lindblad sampler + DemStabSim glue.** +Implement `PauliLindbladModel::sample(t)` via independent Bernoullis +(Section 5). Implement `DemStabNoiseModel` for `PauliLindbladModel` +(skeleton Section "Glue into DemStabSim"). Rep-code memory experiment +parity test. + +**Phase 3 -- closed-form Appendix C lookup.** +Transcribe Tables 1-2 into a Rust `const` table keyed by +`(GateType, PauliLabel)`. Property-test each entry against Phase 1 +numerical path. Add Taylor branches for small $\theta$. + +**Phase 4 -- higher-order Magnus.** +Implement $\Omega_3, \Omega_4$ with Blanes-Casas-Oteo-Ros; verify against +Phase 3 + Phase 1 random Lindbladians. Out-of-regime detection. + +**Phase 5 -- Appendix D multi-qubit ZZ crosstalk.** +Re-scrape paper for D.7/D.8 formulae. Transcribe. Property-test. 200-300 +entries. + +Phases 1-2 are the MVP that unblocks DemStabSim-with-Lindblad-noise. +Phases 3-5 are refinements. + +--- + +## 9. References + +Paper: +- arXiv:2502.03462 -- Malekakhlagh et al., *Efficient Lindblad synthesis* +- arXiv:2201.09866 -- van den Berg et al., *Sparse Pauli-Lindblad PEC* +- arXiv:2311.15408 -- Chen et al., *Learning sparse PL* + +Cross-check: +- arXiv:2407.03576 -- 4th-order commutator-free Magnus in Liouville space +- Blanes, Casas, Oteo, Ros, *The Magnus expansion and some of its + applications* (Phys. Rep. 2009) -- textbook for $\Omega_n$ formulae + +Next scout TODO: +- Re-scrape arxiv LaTeX source of 2502.03462 with a tool capable of + `curl + tar`. Extract Tables 3-5 and Appendix D verbatim. Feed into + Phase 5. diff --git a/design/lindblad_sim_skeleton.md b/design/lindblad_sim_skeleton.md index b84b92b2f..0e80b383a 100644 --- a/design/lindblad_sim_skeleton.md +++ b/design/lindblad_sim_skeleton.md @@ -2,7 +2,7 @@ Status: draft (2026-04-12) Target crate: new `pecos-lindblad` (or module inside `pecos-neo`; decision below) -Pairs with: `design/qec_sim_literature.md` (#7), `design/dem_stab_sim_skeleton.md`, `design/stab_sample_orchestration.md` +Pairs with: `design/qec_sim_literature.md` (#7), `design/lindblad_magnus_algorithm.md` (math spec + closed forms), `design/dem_stab_sim_skeleton.md`, `design/stab_sample_orchestration.md` ## Goals in one paragraph @@ -215,9 +215,17 @@ impl NoiseChannel for LindbladChannel { } ``` -**Pre-req:** `NoiseEvent::AfterGate` must grow a `duration` field (today only -`IdleTime` carries duration). Small, localized change in `pecos-neo/src/noise.rs` --- flag as first integration PR. Without this the lookup table can't be keyed. +**Pre-req path (audit 2026-04-12, revised).** No first-class duration field +exists on `GateCommand` / `NoiseEvent::AfterGate`. Instead of a schema change, +use the existing `TickCircuit` / `DagCircuit` `Attribute` metadata dictionary +(`crates/pecos-quantum/src/tick_circuit.rs:1147`): standardize on the key +`"gate_duration"` = `Attribute::Float(nanoseconds)`. The `pecos-neo` circuit +converter reads this key at translation time into `GateCommand`, and +`LindbladChannel` queries it via `ctx` at apply time. Zero breaking changes +to core circuit types. The schema-extension option (adding +`duration: Option` to `NoiseEvent::AfterGate`) is reserved for a +later PR if the metadata convention proves insufficient -- grug do not prepay +that complexity. ## Noise-model input hierarchy @@ -280,9 +288,10 @@ plus sign/phase. Sparse storage `Vec<(PauliString, f64)>` for 6. **End-to-end DemStabSim glue.** Small rep-code memory experiment: feed `MagnusSynth` output to `DemStabSim`, compare logical error rate against the trajectory path (path b) on the same circuit. -7. **Integration regression.** After `NoiseEvent::AfterGate::duration` lands - in `pecos-neo`, add a parity test with `LindbladChannel` vs - `DemStabSim + PauliLindbladModel` on identical circuit. +7. **Integration regression.** Once the `"gate_duration"` metadata convention + lands in `pecos-neo`'s circuit converter, add a parity test with + `LindbladChannel` vs `DemStabSim + PauliLindbladModel` on the same + circuit annotated with per-gate durations. ## Rejection / validation @@ -320,9 +329,19 @@ plus sign/phase. Sparse storage `Vec<(PauliString, f64)>` for can we parse paper's LaTeX / Mathematica output, or transcribe? Manual transcription of 3-4 closed forms is honest work; skip symbolic pipelines. -- [ ] Gate-duration data path: does `TickCircuit` today carry per-gate - duration metadata, or is duration attached at noise-lookup time via a - separate `GateDurationTable`? Audit `crates/pecos-circuits`. +- [x] Gate-duration data path (**audit 2026-04-12**): no first-class field + on `GateCommand`, `TickCircuit`, `DagCircuit`, or `NoiseEvent::AfterGate`. + Only `GateCommand::idle(qubit, duration)` (stashed in `angles`, see + `exp/pecos-neo/src/command.rs:296`) and `NoiseEvent::IdleTime { duration }` + (`exp/pecos-neo/src/noise.rs:203-206`) carry duration today. **Decision:** + use `TickCircuit` / `DagCircuit` `Attribute` metadata dictionary + (`crates/pecos-quantum/src/tick_circuit.rs:1147`) with standardized key + `"gate_duration"` = `Attribute::Float(ns)`. Lower-risk than a schema + change; zero breaking changes to core circuit types. The + `pecos-neo/src/circuit.rs` converter reads this key when translating + to `GateCommand`; `LindbladChannel` queries it at lookup time. Promote + to a first-class field on `NoiseEvent::AfterGate` only if the metadata + convention proves itself insufficient in practice. - [ ] Seeding semantics for `MagnusSynth` (deterministic, no RNG needed) vs `TrajectorySim` (per-trajectory seed). Document clearly. @@ -338,8 +357,9 @@ plus sign/phase. Sparse storage `Vec<(PauliString, f64)>` for `PauliLindbladModel`. Tests: #6. 5. **`TrajectorySim`** (Path b) -- MCWF, rayon fan-out. Tests: #4 properly, small rep-code validation run. -6. **`NoiseEvent::AfterGate::duration` + `LindbladChannel`** in `pecos-neo`. - Tests: #7. +6. **`"gate_duration"` metadata convention + `LindbladChannel`** in + `pecos-neo` (converter reads `TickCircuit` attribute; channel looks up + cached Pauli rates). Tests: #7. 7. **Higher-order Magnus (3, 4)** + convergence detection. Tests: #3. Stop after step 4 if that's all that's needed for the next research run. From 05378ec36c2b049e6c72e0b6aeee8650853d7115 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 09:29:35 -0600 Subject: [PATCH 012/125] Verify Magnus/crosstalk formulas against 2502.03462 latex source --- design/lindblad_magnus_algorithm.md | 227 +++++++++++++++++++++------- 1 file changed, 169 insertions(+), 58 deletions(-) diff --git a/design/lindblad_magnus_algorithm.md b/design/lindblad_magnus_algorithm.md index 5e38bc01c..c384e8d99 100644 --- a/design/lindblad_magnus_algorithm.md +++ b/design/lindblad_magnus_algorithm.md @@ -11,10 +11,10 @@ arXiv:2502.03462v1. Equation numbers below from the v1 HTML. *Probabilistic error cancellation with sparse Pauli-Lindblad models*, Nat. Phys. 2023, arXiv:2201.09866 (sparse PL generator + Pauli fidelity). -**Caveat (scout).** Scout could not run shell / tar-extract the arxiv -source tarball; spec derived from arxiv HTML endpoints. Tables 3-5 and -Appendix D (3/4-qubit ZZ crosstalk) not verbatim -- manual re-scrape -required before Rust transcription. +**Source status (2026-04-12).** LaTeX tarball extracted to +`/tmp/lindblad_tex/Main.tex` (1082 lines). All closed-form $\lambda_k$ +expressions below are verbatim from the tex source; equation-label +references are authoritative. --- @@ -68,7 +68,13 @@ Omega_2 = 0.5 * integrate_double( Omega_3 = (1/6) * integrate_triple( comm(L_I(t1), comm(L_I(t2), L_I(t3))) + comm(L_I(t3), comm(L_I(t2), L_I(t1))), 0 <= t3 <= t2 <= t1 <= tau_g ) -Omega_4 = // Blanes-Casas-Oteo-Ros 4-commutator formula (paper App. C) +// VERIFIED prefactor is 1/12 (paper eq. TDLindPT-G4 Sol), NOT 1/24 (BCOR textbook). +Omega_4 = (1/12) * integrate_quadruple( + comm(L_I(t'), comm(L_I(t''), comm(L_I(t'''), L_I(t'''')))) + + comm(L_I(t'), comm([L_I(t''), L_I(t''')], L_I(t''''))) + + comm([[L_I(t'), L_I(t'')], L_I(t''')], L_I(t'''')) + + comm(L_I(t''), comm(L_I(t'''), comm(L_I(t''''), L_I(t')))), + 0 <= t'''' <= t''' <= t'' <= t' <= tau_g ) // Step 3 -- effective generator (paper eq. 9-10) L_eff = (1/tau_g) * sum_{n=1..N} Omega_n @@ -100,82 +106,181 @@ and must be small under the weak-noise assumption -- assert --- -## 3. Closed-form fixtures (Appendix C, Tables 1-2) +## 3. Closed-form fixtures (Appendix E / `App:WhyPauliLind`) -Transcribed for the golden-test path. Index convention: $P_b$ written as -two-letter label `ab` = $P_a \otimes P_b$ on (left, right) qubit; -$i\equiv I$. Rates $\beta_{\downarrow l}, \beta_{\downarrow r}$ are -amplitude-damping on (left, right) qubit; $\beta_\phi$ is pure dephasing. +All expressions verbatim from `/tmp/lindblad_tex/Main.tex`. Index convention: +$P_b$ written as string label `ab` = $P_a \otimes P_b$ on (left, right) qubit; +$i\equiv I$. Rates: $\beta_{\downarrow j}$ amplitude damping on qubit $j$, +$\beta_{\phi j}$ pure dephasing on qubit $j$, for $j\in\{l, r\}$. -### Amplitude damping, Table 1 +### Single-qubit identity + AD + PD (exact, non-perturbative) -Identity $I_{\tau_g}$: +Paper line 812, $\tau_g$-scale: $$ -\lambda_{ix}=\lambda_{iy}=\tfrac14\beta_{\downarrow r}\tau_g,\quad -\lambda_{xi}=\lambda_{yi}=\tfrac14\beta_{\downarrow l}\tau_g; -\text{ rest } = 0. +\lambda_x = \lambda_y = \tfrac14\beta_{\downarrow}\tau_g,\quad +\lambda_z = \tfrac12\beta_\phi\tau_g. $$ +Not perturbative -- exact twirled result for identity. -$CZ_\theta$ ($\theta = \omega_{cz}\tau_g$): +### Single-qubit $X_\theta$ + AD + PD (paper eqs. 869-874) + +$$ +\lambda_x = \tfrac{\theta}{4}\tfrac{\beta_\downarrow}{\omega_x}, +$$ +$$ +\lambda_y = \tfrac{2\theta+\sin 2\theta}{16}\tfrac{\beta_\downarrow}{\omega_x} + + \tfrac{2\theta-\sin 2\theta}{8}\tfrac{\beta_\phi}{\omega_x}, +$$ +$$ +\lambda_z = \tfrac{2\theta-\sin 2\theta}{16}\tfrac{\beta_\downarrow}{\omega_x} + + \tfrac{2\theta+\sin 2\theta}{8}\tfrac{\beta_\phi}{\omega_x}. +$$ + +### Two-qubit $CZ_\theta$ + AD + PD (paper eqs. 896-906) + +$\theta = \omega_{cz}\tau_g$. PD contributions separable from AD: +$$ +\lambda_{iz} = \tfrac{\theta}{2}\tfrac{\beta_{\phi r}}{\omega_{cz}},\quad +\lambda_{zi} = \tfrac{\theta}{2}\tfrac{\beta_{\phi l}}{\omega_{cz}}, +$$ $$ \lambda_{ix}=\lambda_{iy}=\tfrac{2\theta+\sin 2\theta}{16}\tfrac{\beta_{\downarrow r}}{\omega_{cz}},\quad \lambda_{xi}=\lambda_{yi}=\tfrac{2\theta+\sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cz}}, $$ $$ -\lambda_{xz}=\lambda_{yz}=\tfrac{2\theta-\sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cz}},\quad -\lambda_{zx}=\lambda_{zy}=\tfrac{2\theta-\sin 2\theta}{16}\tfrac{\beta_{\downarrow r}}{\omega_{cz}}. +\lambda_{zx}=\lambda_{zy}=\tfrac{2\theta-\sin 2\theta}{16}\tfrac{\beta_{\downarrow r}}{\omega_{cz}},\quad +\lambda_{xz}=\lambda_{yz}=\tfrac{2\theta-\sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cz}}. $$ +At Clifford angles $\theta = n\pi/2$ the degeneracy becomes 4-fold: +$\lambda_{ix}=\lambda_{iy}=\lambda_{zx}=\lambda_{zy}$ and +$\lambda_{xi}=\lambda_{yi}=\lambda_{xz}=\lambda_{yz}$. + +### Two-qubit $CX_\theta$ + AD + PD (paper eqs. 929-956) -$CX_\theta$ ($\theta = \omega_{cx}\tau_g$): +$\theta = \omega_{cx}\tau_g$. AD and PD **mix** in $\lambda_{iy}, \lambda_{iz}, +\lambda_{zy}, \lambda_{zz}$: +$$ +\lambda_{ix} = \tfrac{\theta}{4}\tfrac{\beta_{\downarrow r}}{\omega_{cx}},\quad +\lambda_{zi} = \tfrac{\theta}{2}\tfrac{\beta_{\phi l}}{\omega_{cx}}, +$$ +$$ +\lambda_{iy} = \tfrac{12\theta + 8\sin 2\theta + \sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}} + + \tfrac{4\theta - \sin 4\theta}{64}\tfrac{\beta_{\phi r}}{\omega_{cx}}, $$ -\lambda_{ix}=\tfrac{\theta}{4}\tfrac{\beta_{\downarrow r}}{\omega_{cx}},\quad -\lambda_{iy}=\tfrac{12\theta+8\sin 2\theta+\sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}}, $$ +\lambda_{iz} = \tfrac{4\theta - \sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}} + + \tfrac{12\theta + 8\sin 2\theta + \sin 4\theta}{64}\tfrac{\beta_{\phi r}}{\omega_{cx}}, $$ -\lambda_{iz}=\lambda_{zz}=\tfrac{4\theta-\sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}},\quad -\lambda_{xi}=\lambda_{yi}=\tfrac{2\theta+\sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cx}}, $$ +\lambda_{zy} = \tfrac{12\theta - 8\sin 2\theta + \sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}} + + \tfrac{4\theta - \sin 4\theta}{64}\tfrac{\beta_{\phi r}}{\omega_{cx}}, $$ -\lambda_{xx}=\lambda_{yx}=\tfrac{2\theta-\sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cx}},\quad -\lambda_{zy}=\tfrac{12\theta-8\sin 2\theta+\sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}}. $$ +\lambda_{zz} = \tfrac{4\theta - \sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}} + + \tfrac{12\theta - 8\sin 2\theta + \sin 4\theta}{64}\tfrac{\beta_{\phi r}}{\omega_{cx}}, +$$ +$$ +\lambda_{xi} = \lambda_{yi} = \tfrac{2\theta + \sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cx}},\quad +\lambda_{xx} = \lambda_{yx} = \tfrac{2\theta - \sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cx}}. +$$ + +**Correction from earlier scout.** Initial scout transcribed +$\lambda_{iz}=\lambda_{zz}=\frac{4\theta-\sin 4\theta}{128}\frac{\beta_{\downarrow r}}{\omega_{cx}}$ +and missed PD contributions entirely. Verbatim paper formulae above +supersede. -### Pure dephasing, Table 2 +### Two-qubit phase noise (subsection SubApp:2QPhNoise, lines 962-1001) -Only $\lambda_{iz}, \lambda_{zi}, \lambda_{iy}, \lambda_{zy}, \lambda_{zz}$ -nonzero. +Quadratic-in-$\delta$ dependence (coherent noise $H_\delta = (\delta/2)ZZ$). +Not transcribed here; see paper lines 962-1001 if PECOS needs coherent- +noise fixtures before v1 ships. -Identity: $\lambda_{iz}=\tfrac12\beta_{\phi r}\tau_g$, -$\lambda_{zi}=\tfrac12\beta_{\phi l}\tau_g$. +### Three-qubit ZZ crosstalk (paper eqs. 1009-1011) -$CX_\theta$: +**Only non-trivial case**: $CX_\theta \otimes I$ with $IZZ$ crosstalk between +target and spectator. $H_g = (\omega_{cz}/2)(IXI-ZXI)$, +$H_\delta = (\delta_{izz}/2)IZZ$. Produces weight-2 **and weight-3** PL terms: $$ -\lambda_{iz}=\tfrac{12\theta+8\sin 2\theta+\sin 4\theta}{64}\tfrac{\beta_{\phi r}}{\omega_{cx}},\quad -\lambda_{zz}=\tfrac{12\theta-8\sin 2\theta+\sin 4\theta}{64}\tfrac{\beta_{\phi r}}{\omega_{cx}}. +\lambda_{iyz} = \lambda_{zyz} = \tfrac{\sin^4\theta}{16}\tfrac{\delta_{izz}^2}{\omega_{cx}^2}, $$ +$$ +\lambda_{izz} = \tfrac{[2\theta + \sin 2\theta]^2}{64}\tfrac{\delta_{izz}^2}{\omega_{cx}^2},\quad +\lambda_{zzz} = \tfrac{[2\theta - \sin 2\theta]^2}{64}\tfrac{\delta_{izz}^2}{\omega_{cx}^2}. +$$ +**Important for PECOS:** weight-3 terms break the standard weight-2-only +sparse-PL sparsity assumption -- `PauliLindbladModel` must allow +user-specified basis $\mathcal{K}$ with weight > 2. -**Test fixture usage.** Feed $H_{CR}$ and $L\in\{\sigma^-, Z\}$ into the -algorithm; compare against these closed forms to `< 1e-10`. The cases above -are the minimum golden set; extend with CZ pure-dephasing and CX non-left -cases from Tables 1-2 (not transcribed here -- see paper). +### Four-qubit ZZ crosstalk (paper eqs. 1044-1062) ---- +Only case (iv) -- $CX_\theta \otimes X_\theta C$ with $IZZI$ crosstalk on +middle two qubits -- is non-trivial (case (iii) reduces to 3Q). Yields +weight-3 and weight-4 PL terms. + +$H_g = (\omega_{cx}/2)[(IXII-ZXII) + (IIIX-IIZX)]$, +$H_\delta = (\delta_{izzi}/2)IZZI$: +$$ +\lambda_{iyyi} = \lambda_{iyyz} = \lambda_{izzz} = \lambda_{zyyi} = \lambda_{zyyz} += \tfrac{[4\theta - \sin 4\theta]^2}{4096}\tfrac{\delta_{izzi}^2}{\omega_{cx}^2}, +$$ +$$ +\lambda_{iyzi} = \lambda_{izyi} = \lambda_{iyzz} = \lambda_{zzyi} += \tfrac{\sin^4\theta [3 + \cos 2\theta]^2}{256}\tfrac{\delta_{izzi}^2}{\omega_{cx}^2}, +$$ +$$ +\lambda_{iyzz} = \lambda_{zyzz} = \lambda_{zzyi} = \lambda_{zzyz} += \tfrac{\sin^8\theta}{64}\tfrac{\delta_{izzi}^2}{\omega_{cx}^2}, +$$ +$$ +\lambda_{izzi} = \tfrac{[12\theta + 8\sin 2\theta + \sin 4\theta]^2}{4096}\tfrac{\delta_{izzi}^2}{\omega_{cx}^2}, +$$ +$$ +\lambda_{zzzz} = \tfrac{[12\theta - 8\sin 2\theta + \sin 4\theta]^2}{4096}\tfrac{\delta_{izzi}^2}{\omega_{cx}^2}. +$$ -## 4. Appendix D: multi-qubit ZZ crosstalk +Note: paper appears to have duplicate labels in the first group +($\lambda_{iyyz}$ appears twice) -- possible typo; verify against any +erratum before Rust transcription. -- **D.7** -- three-qubit ZZ crosstalk. -- **D.8** -- four-qubit ZZ crosstalk. +### Leading-order precision (paper App:LindPertPrecision) -**Form.** Plain LaTeX tables; *not* SymPy/Mathematica-parseable. -Each cell is a rational in $\theta$ with $\sin/\cos$ and one -$\beta/\omega$ factor. +For $CX_{\pi/4}$ at $\beta_\downarrow/\omega_{cx} \approx 10^{-2}$: deviation +$\sim O(10^{-5})$. At $10^{-1}$: deviation $\sim O(10^{-4})$. Use as +guidance for convergence-regime defaults in `MagnusSynth`. -**Effort estimate.** Tables 1-2 alone contain ~20 distinct formulae per -gate column. Extrapolating to D.7+D.8 plus remaining Tables 3-5 yields -roughly **200-300 closed-form $\lambda_k$ formulae total**. Transcribe -into a Rust lookup `(gate_type, pauli_label) -> fn(theta, beta, omega) --> f64`. One focused afternoon of careful typing + property-test each -entry against the numerical (Magnus-integrated) path. +**Test fixture usage.** Feed $H_{CR}$ or $H_{CZ}$ and $L\in\{\sigma^-, Z\}$ +into the algorithm; compare against closed forms to `< 1e-10`. For 3Q/4Q +crosstalk, feed $H_\delta = (\delta/2)P$ (coherent, not incoherent) and +verify quadratic scaling in $\delta$. + +--- + +## 4. Effort revision (post-latex-extract) + +**Scout initial estimate:** 200-300 formulae. **Actual (from verbatim +tex extract):** ~25-30 distinct $\lambda_k$ expressions across the +whole appendix. Most cases collapse: paper notes "the only non-trivial +case is $CX_\theta \otimes I$ with $IZZ$" etc. Much less transcription +work than scout estimated. + +Breakdown of distinct formulae: +- 1Q identity (AD+PD): 3 entries (non-perturbative). +- 1Q $X_\theta$: 3 entries with AD+PD mixing. +- 2Q $CZ_\theta$: 8 entries (mostly 2-fold/4-fold degenerate). +- 2Q $CX_\theta$: 9 entries with AD+PD mixing on 4 of them. +- 2Q phase noise: untranscribed; coherent ZZ, quadratic in $\delta$ + (lines 962-1001). +- 3Q ZZ crosstalk: 3 entries ($CX \otimes I$ only). +- 4Q ZZ crosstalk: 5 groups (many-fold degenerate) for + $CX_\theta \otimes X_\theta C$ only. + +Rust lookup form: `(gate_type, pauli_label) -> fn(theta, beta_ad_l, +beta_ad_r, beta_pd_l, beta_pd_r, omega) -> f64`. One afternoon. Test each +against a numerical Magnus order-2 integration on the same inputs. + +**Ambiguity flag.** Paper's 4Q section has an apparent label typo +(`lambda_iyyz` listed twice in one group). Manual review + possible +erratum check required. --- @@ -245,11 +350,13 @@ tracked; forward QEC simulation uses $\lambda_k \ge 0$ only. (lossy), warn/error on negative, or bump order (expensive). Start with "warn + clip" and log the truncation residual. -- **Omega_3 / Omega_4 prefactor verification.** Scout could not extract - Appendix C verbatim through the HTML endpoints. Blanes-Casas-Oteo-Ros - recurrence is the textbook safe default; first implementation must - regression-test against Tables 1-2 closed forms before trusting higher - orders. **Blocking item for order $>2$.** +- **Omega_3 / Omega_4 prefactor verification.** Resolved (2026-04-12): + $\Omega_3$ has prefactor $1/6$ and $\Omega_4$ has prefactor **$1/12$** + (paper eq. TDLindPT-G4 Sol, line 688 of Main.tex), with 4 specific + nested-commutator terms explicitly listed. Note: textbook BCOR uses + $1/24$ with a different term decomposition -- the paper's form is + equivalent by commutator identities but the prefactor is $1/12$ as + written. Use paper's form verbatim. - **Time-dependent $H_g(t)$.** Paper assumes quasi-time-independent. Real pulse shapes (Gaussian, DRAG) break this. Dyson path handles @@ -318,6 +425,10 @@ Cross-check: applications* (Phys. Rep. 2009) -- textbook for $\Omega_n$ formulae Next scout TODO: -- Re-scrape arxiv LaTeX source of 2502.03462 with a tool capable of - `curl + tar`. Extract Tables 3-5 and Appendix D verbatim. Feed into - Phase 5. +- 2Q phase noise (paper subsection SubApp:2QPhNoise, lines 962-1001): + coherent-noise test fixtures. Low priority; only needed if coherent + $ZZ$ test path is in v1. +- Verify paper's apparent 4Q label typo ($\lambda_{iyyz}$ listed twice). + +Source checked out at `/tmp/lindblad_tex/Main.tex` (ephemeral). For a +permanent copy, pull from `arxiv.org/e-print/2502.03462`. From b7d85a8dff25b685362b7eab9bc977819c465d13 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 10:03:21 -0600 Subject: [PATCH 013/125] Scaffold exp/pecos-lindblad with 1Q identity synthesis (Phase 1) --- Cargo.lock | 10 +++ Cargo.toml | 1 + exp/pecos-lindblad/Cargo.toml | 23 +++++ exp/pecos-lindblad/README.md | 16 ++++ exp/pecos-lindblad/src/basis.rs | 103 +++++++++++++++++++++ exp/pecos-lindblad/src/gate.rs | 44 +++++++++ exp/pecos-lindblad/src/lib.rs | 35 ++++++++ exp/pecos-lindblad/src/lindbladian.rs | 58 ++++++++++++ exp/pecos-lindblad/src/matrix.rs | 108 +++++++++++++++++++++++ exp/pecos-lindblad/src/pauli_lindblad.rs | 97 ++++++++++++++++++++ exp/pecos-lindblad/src/synthesis.rs | 77 ++++++++++++++++ exp/pecos-lindblad/tests/identity_1q.rs | 95 ++++++++++++++++++++ 12 files changed, 667 insertions(+) create mode 100644 exp/pecos-lindblad/Cargo.toml create mode 100644 exp/pecos-lindblad/README.md create mode 100644 exp/pecos-lindblad/src/basis.rs create mode 100644 exp/pecos-lindblad/src/gate.rs create mode 100644 exp/pecos-lindblad/src/lib.rs create mode 100644 exp/pecos-lindblad/src/lindbladian.rs create mode 100644 exp/pecos-lindblad/src/matrix.rs create mode 100644 exp/pecos-lindblad/src/pauli_lindblad.rs create mode 100644 exp/pecos-lindblad/src/synthesis.rs create mode 100644 exp/pecos-lindblad/tests/identity_1q.rs diff --git a/Cargo.lock b/Cargo.lock index ca49b3380..edfd482f7 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -3894,6 +3894,16 @@ dependencies = [ "thiserror 2.0.18", ] +[[package]] +name = "pecos-lindblad" +version = "0.2.0-dev.0" +dependencies = [ + "approx 0.5.1", + "num-complex 0.4.6", + "rand 0.10.0", + "thiserror 2.0.18", +] + [[package]] name = "pecos-llvm" version = "0.2.0-dev.0" diff --git a/Cargo.toml b/Cargo.toml index 7ea294015..69f0434f7 100644 --- a/Cargo.toml +++ b/Cargo.toml @@ -179,6 +179,7 @@ pecos-gpu-sims = { version = "0.2.0-dev.0", path = "crates/pecos-gpu-sims" } pecos-hugr = { version = "0.2.0-dev.0", path = "crates/pecos-hugr" } pecos-hugr-qis = { version = "0.2.0-dev.0", path = "crates/pecos-hugr-qis" } pecos-ldpc-decoders = { version = "0.2.0-dev.0", path = "crates/pecos-ldpc-decoders" } +pecos-lindblad = { version = "0.2.0-dev.0", path = "exp/pecos-lindblad" } pecos-llvm = { version = "0.2.0-dev.0", path = "crates/pecos-llvm" } pecos-neo = { version = "0.2.0-dev.0", path = "exp/pecos-neo" } pecos-num = { version = "0.2.0-dev.0", path = "crates/pecos-num" } diff --git a/exp/pecos-lindblad/Cargo.toml b/exp/pecos-lindblad/Cargo.toml new file mode 100644 index 000000000..46046ed79 --- /dev/null +++ b/exp/pecos-lindblad/Cargo.toml @@ -0,0 +1,23 @@ +[package] +name = "pecos-lindblad" +version.workspace = true +edition.workspace = true +authors.workspace = true +homepage.workspace = true +repository.workspace = true +license.workspace = true +keywords.workspace = true +categories.workspace = true +description = "Lindblad-to-Pauli-Lindblad noise synthesis for PECOS" +readme = "README.md" + +[lib] +crate-type = ["rlib"] + +[dependencies] +num-complex.workspace = true +thiserror.workspace = true +rand.workspace = true + +[dev-dependencies] +approx = "0.5" diff --git a/exp/pecos-lindblad/README.md b/exp/pecos-lindblad/README.md new file mode 100644 index 000000000..6f8965f35 --- /dev/null +++ b/exp/pecos-lindblad/README.md @@ -0,0 +1,16 @@ +# pecos-lindblad + +Lindblad-to-Pauli-Lindblad noise synthesis for PECOS. + +Given a per-gate Lindbladian `{H_ideal, H_err, c_ops, tau_g}`, compute the +effective Pauli-Lindblad rates `lambda_k` that feed into +`pecos-qec::DemStabSim` or any Pauli-level noise channel. + +**Status:** experimental, Phase 1 (numerical baseline + 1Q identity test). + +**Design docs:** +- `design/lindblad_sim_skeleton.md` -- crate layout, API surface, test plan +- `design/lindblad_magnus_algorithm.md` -- math spec, closed forms, references + +**Primary reference:** Malekakhlagh et al., *Efficient Lindblad synthesis for +noise model construction*, npj QI 2025, arXiv:2502.03462. diff --git a/exp/pecos-lindblad/src/basis.rs b/exp/pecos-lindblad/src/basis.rs new file mode 100644 index 000000000..d7e72298a --- /dev/null +++ b/exp/pecos-lindblad/src/basis.rs @@ -0,0 +1,103 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Pauli basis types for Lindblad -> Pauli-Lindblad synthesis. + +use std::fmt; + +/// Single-qubit Pauli operator. +#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)] +#[repr(u8)] +pub enum Pauli1 { + I = 0, + X = 1, + Y = 2, + Z = 3, +} + +impl Pauli1 { + pub fn from_char(c: char) -> Option { + match c { + 'I' | 'i' => Some(Pauli1::I), + 'X' | 'x' => Some(Pauli1::X), + 'Y' | 'y' => Some(Pauli1::Y), + 'Z' | 'z' => Some(Pauli1::Z), + _ => None, + } + } + + pub fn to_char(self) -> char { + match self { + Pauli1::I => 'I', + Pauli1::X => 'X', + Pauli1::Y => 'Y', + Pauli1::Z => 'Z', + } + } +} + +/// Multi-qubit Pauli string. Index 0 = leftmost factor. +#[derive(Clone, Debug, PartialEq, Eq, Hash)] +pub struct PauliString(pub Vec); + +impl PauliString { + pub fn single(p: Pauli1) -> Self { + PauliString(vec![p]) + } + + pub fn from_str(s: &str) -> Option { + s.chars().map(Pauli1::from_char).collect::>>().map(PauliString) + } + + pub fn num_qubits(&self) -> usize { + self.0.len() + } + + /// Weight (number of non-identity factors). + pub fn weight(&self) -> usize { + self.0.iter().filter(|&&p| p != Pauli1::I).count() + } +} + +impl fmt::Display for PauliString { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + for p in &self.0 { + write!(f, "{}", p.to_char())?; + } + Ok(()) + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn roundtrip_string() { + let s = PauliString::from_str("XYZ").unwrap(); + assert_eq!(s.num_qubits(), 3); + assert_eq!(s.weight(), 3); + assert_eq!(format!("{}", s), "XYZ"); + } + + #[test] + fn identity_weight() { + let s = PauliString::from_str("III").unwrap(); + assert_eq!(s.weight(), 0); + } + + #[test] + fn mixed_weight() { + let s = PauliString::from_str("IXI").unwrap(); + assert_eq!(s.weight(), 1); + } +} diff --git a/exp/pecos-lindblad/src/gate.rs b/exp/pecos-lindblad/src/gate.rs new file mode 100644 index 000000000..4f4061d9d --- /dev/null +++ b/exp/pecos-lindblad/src/gate.rs @@ -0,0 +1,44 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Gate type: ideal Hamiltonian + noise Lindbladian + duration. + +use crate::lindbladian::Lindbladian; + +/// A physical gate with its ideal rotation, noise model, and duration. +#[derive(Clone, Debug)] +pub struct Gate { + pub label: String, + pub num_qubits: usize, + /// Noise-free part of the dynamics. Sets the interaction frame. + pub ideal: Lindbladian, + /// Noise (coherent + incoherent) applied during the gate. + pub noise: Lindbladian, + /// Gate duration in the same time units as `gamma_j` of the noise. + pub tau_g: f64, +} + +impl Gate { + /// Identity gate (no ideal Hamiltonian) with a given noise Lindbladian + /// and duration. + pub fn identity(num_qubits: usize, noise: Lindbladian, tau_g: f64) -> Self { + let d = 1 << num_qubits; + assert_eq!(noise.d, d, "noise dim mismatch"); + Self { + label: "I".to_string(), + num_qubits, + ideal: Lindbladian::zero(d), + noise, + tau_g, + } + } +} diff --git a/exp/pecos-lindblad/src/lib.rs b/exp/pecos-lindblad/src/lib.rs new file mode 100644 index 000000000..d0f881445 --- /dev/null +++ b/exp/pecos-lindblad/src/lib.rs @@ -0,0 +1,35 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! # pecos-lindblad +//! +//! Lindblad-to-Pauli-Lindblad noise synthesis for PECOS. +//! +//! Phase 1 (current): 1-qubit identity-gate synthesis. Produces a +//! [`PauliLindbladModel`] from a [`Gate`] carrying a noise [`Lindbladian`] +//! and duration. +//! +//! Reference: Malekakhlagh et al., arXiv:2502.03462 (npj QI 2025). +//! See `design/lindblad_magnus_algorithm.md` for the math spec. + +pub mod basis; +pub mod gate; +pub mod lindbladian; +pub mod matrix; +pub mod pauli_lindblad; +pub mod synthesis; + +pub use basis::{Pauli1, PauliString}; +pub use gate::Gate; +pub use lindbladian::Lindbladian; +pub use pauli_lindblad::PauliLindbladModel; +pub use synthesis::synthesize_identity_1q; diff --git a/exp/pecos-lindblad/src/lindbladian.rs b/exp/pecos-lindblad/src/lindbladian.rs new file mode 100644 index 000000000..add5419ed --- /dev/null +++ b/exp/pecos-lindblad/src/lindbladian.rs @@ -0,0 +1,58 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Lindbladian type: Hermitian Hamiltonian plus rate-weighted collapse operators. + +use num_complex::Complex64; + +use crate::matrix::{self, Matrix}; + +/// Time-independent Lindbladian of form +/// `drho/dt = -i[H, rho] + sum_j gamma_j * D[c_j] rho` +/// where `D[c] rho = c rho c^dag - 1/2 {c^dag c, rho}`. +#[derive(Clone, Debug)] +pub struct Lindbladian { + pub d: usize, + pub hamiltonian: Matrix, + pub collapse: Vec<(Matrix, f64)>, +} + +impl Lindbladian { + pub fn new(d: usize, hamiltonian: Matrix, collapse: Vec<(Matrix, f64)>) -> Self { + assert_eq!(hamiltonian.len(), d * d, "hamiltonian wrong shape"); + for (c, _) in &collapse { + assert_eq!(c.len(), d * d, "collapse op wrong shape"); + } + Self { d, hamiltonian, collapse } + } + + /// Zero Hamiltonian with no collapse ops (no-op). + pub fn zero(d: usize) -> Self { + Self { d, hamiltonian: matrix::zeros(d), collapse: Vec::new() } + } + + /// Apply `L` to a matrix `rho`. Returns `L(rho)`. + pub fn apply(&self, rho: &Matrix) -> Matrix { + let d = self.d; + let neg_i = Complex64::new(0.0, -1.0); + let mut out = matrix::scale(&matrix::commutator(&self.hamiltonian, rho, d), neg_i); + for (c, gamma) in &self.collapse { + let cdag = matrix::dag(c, d); + let c_rho_cdag = matrix::matmul(&matrix::matmul(c, rho, d), &cdag, d); + let cdag_c = matrix::matmul(&cdag, c, d); + let acom = matrix::anticommutator(&cdag_c, rho, d); + let diss = matrix::sub(&c_rho_cdag, &matrix::scale(&acom, Complex64::new(0.5, 0.0))); + out = matrix::add(&out, &matrix::scale(&diss, Complex64::new(*gamma, 0.0))); + } + out + } +} diff --git a/exp/pecos-lindblad/src/matrix.rs b/exp/pecos-lindblad/src/matrix.rs new file mode 100644 index 000000000..527e731f9 --- /dev/null +++ b/exp/pecos-lindblad/src/matrix.rs @@ -0,0 +1,108 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Minimal dense complex-matrix helpers for Phase 1. +//! +//! Matrices are stored row-major as `Vec` of length `d*d`. Caller +//! tracks `d`. This is intentionally primitive -- swap to faer / ndarray once +//! Phase 1 numbers prove out. + +use num_complex::Complex64; + +use crate::basis::Pauli1; + +pub type Matrix = Vec; + +pub fn zeros(d: usize) -> Matrix { + vec![Complex64::new(0.0, 0.0); d * d] +} + +pub fn identity(d: usize) -> Matrix { + let mut m = zeros(d); + for i in 0..d { + m[i * d + i] = Complex64::new(1.0, 0.0); + } + m +} + +pub fn matmul(a: &Matrix, b: &Matrix, d: usize) -> Matrix { + let mut c = zeros(d); + for i in 0..d { + for k in 0..d { + let aik = a[i * d + k]; + if aik == Complex64::new(0.0, 0.0) { + continue; + } + for j in 0..d { + c[i * d + j] += aik * b[k * d + j]; + } + } + } + c +} + +/// Conjugate transpose. +pub fn dag(a: &Matrix, d: usize) -> Matrix { + let mut b = zeros(d); + for i in 0..d { + for j in 0..d { + b[j * d + i] = a[i * d + j].conj(); + } + } + b +} + +pub fn trace(a: &Matrix, d: usize) -> Complex64 { + (0..d).map(|i| a[i * d + i]).sum() +} + +pub fn scale(a: &Matrix, s: Complex64) -> Matrix { + a.iter().map(|x| x * s).collect() +} + +pub fn add(a: &Matrix, b: &Matrix) -> Matrix { + a.iter().zip(b.iter()).map(|(x, y)| x + y).collect() +} + +pub fn sub(a: &Matrix, b: &Matrix) -> Matrix { + a.iter().zip(b.iter()).map(|(x, y)| x - y).collect() +} + +/// `A*B - B*A`. +pub fn commutator(a: &Matrix, b: &Matrix, d: usize) -> Matrix { + sub(&matmul(a, b, d), &matmul(b, a, d)) +} + +/// `A*B + B*A`. +pub fn anticommutator(a: &Matrix, b: &Matrix, d: usize) -> Matrix { + add(&matmul(a, b, d), &matmul(b, a, d)) +} + +/// 2x2 Pauli matrix for a single-qubit Pauli operator. +pub fn pauli_1q(p: Pauli1) -> Matrix { + let z = Complex64::new(0.0, 0.0); + let o = Complex64::new(1.0, 0.0); + let i = Complex64::new(0.0, 1.0); + match p { + Pauli1::I => vec![o, z, z, o], + Pauli1::X => vec![z, o, o, z], + Pauli1::Y => vec![z, -i, i, z], + Pauli1::Z => vec![o, z, z, -o], + } +} + +/// Lowering operator sigma_- = |1><0| = [[0,0],[1,0]]. +pub fn sigma_minus() -> Matrix { + let z = Complex64::new(0.0, 0.0); + let o = Complex64::new(1.0, 0.0); + vec![z, z, o, z] +} diff --git a/exp/pecos-lindblad/src/pauli_lindblad.rs b/exp/pecos-lindblad/src/pauli_lindblad.rs new file mode 100644 index 000000000..362b7c192 --- /dev/null +++ b/exp/pecos-lindblad/src/pauli_lindblad.rs @@ -0,0 +1,97 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Sparse Pauli-Lindblad noise model (arXiv:2201.09866 generator form). + +use rand::{Rng, RngExt}; + +use crate::basis::{Pauli1, PauliString}; + +/// Sparse Pauli-Lindblad generator: +/// `N(rho) = exp( sum_k lambda_k * (P_k rho P_k^dag - rho) )`. +/// `rates[i]` is the integrated rate `lambda_k` (dimensionless) for +/// `supports[i]`. All rates are non-negative for forward simulation. +#[derive(Clone, Debug, Default)] +pub struct PauliLindbladModel { + pub supports: Vec, + pub rates: Vec, +} + +impl PauliLindbladModel { + pub fn new(supports: Vec, rates: Vec) -> Self { + assert_eq!(supports.len(), rates.len(), "supports/rates length mismatch"); + for &r in &rates { + assert!(r >= 0.0, "negative PL rate: {}", r); + } + Self { supports, rates } + } + + /// Look up the rate for a given Pauli support. Returns 0 if not present. + pub fn rate(&self, p: &PauliString) -> f64 { + self.supports.iter().zip(&self.rates).find(|(s, _)| *s == p).map(|(_, r)| *r).unwrap_or(0.0) + } + + /// Sample an error realization over integrated duration `t_scale`: + /// each Pauli term independently fires with probability + /// `p_k = (1 - exp(-2 * lambda_k * t_scale)) / 2`. Returns the + /// product Pauli string (may be identity). + pub fn sample(&self, t_scale: f64, rng: &mut impl Rng) -> PauliString { + assert!(!self.supports.is_empty(), "cannot sample empty model"); + let n = self.supports[0].num_qubits(); + let mut acc = vec![Pauli1::I; n]; + for (support, &lambda) in self.supports.iter().zip(&self.rates) { + assert_eq!(support.num_qubits(), n, "ragged supports"); + let p_flip = 0.5 * (1.0 - (-2.0 * lambda * t_scale).exp()); + if rng.random_range(0.0..1.0) < p_flip { + for (a, b) in acc.iter_mut().zip(&support.0) { + *a = pauli_multiply(*a, *b); + } + } + } + PauliString(acc) + } +} + +/// 1-qubit Pauli multiplication (ignoring phase -- supports are Hermitian +/// so phase cancels in `P rho P^dag` style actions). +fn pauli_multiply(a: Pauli1, b: Pauli1) -> Pauli1 { + use Pauli1::*; + match (a, b) { + (I, x) | (x, I) => x, + (X, X) | (Y, Y) | (Z, Z) => I, + (X, Y) | (Y, X) => Z, + (Y, Z) | (Z, Y) => X, + (X, Z) | (Z, X) => Y, + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn sample_zero_rates_is_identity() { + use rand::rngs::StdRng; + use rand::SeedableRng; + let supports = vec![ + PauliString::single(Pauli1::X), + PauliString::single(Pauli1::Y), + PauliString::single(Pauli1::Z), + ]; + let model = PauliLindbladModel::new(supports, vec![0.0; 3]); + let mut rng = StdRng::seed_from_u64(42); + for _ in 0..100 { + let s = model.sample(1.0, &mut rng); + assert_eq!(s, PauliString::single(Pauli1::I)); + } + } +} diff --git a/exp/pecos-lindblad/src/synthesis.rs b/exp/pecos-lindblad/src/synthesis.rs new file mode 100644 index 000000000..083f58311 --- /dev/null +++ b/exp/pecos-lindblad/src/synthesis.rs @@ -0,0 +1,77 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Phase 1: numerical Pauli-Lindblad synthesis for identity gates. +//! +//! For an identity gate (`H_g = 0`) the interaction-frame Lindbladian is +//! time-independent and `Omega_1 = L * tau_g` is exact to first order in the +//! Magnus expansion. For 1-qubit identity with amplitude damping plus pure +//! dephasing the first-order result is already **exact and +//! non-perturbative** (paper arXiv:2502.03462 line 812); see +//! `design/lindblad_magnus_algorithm.md` section 3. + +use crate::basis::{Pauli1, PauliString}; +use crate::gate::Gate; +use crate::matrix::{self, Matrix}; +use crate::pauli_lindblad::PauliLindbladModel; + +/// Synthesize a 1-qubit Pauli-Lindblad model from an identity gate. +/// Supports are `{X, Y, Z}`; rates come from the linear system +/// `alpha_b * tau_g = 2 sum_{k != I} lambda_k * _sp`. +pub fn synthesize_identity_1q(gate: &Gate) -> PauliLindbladModel { + assert_eq!(gate.num_qubits, 1, "synthesize_identity_1q requires 1 qubit"); + assert!( + is_zero_hamiltonian(&gate.ideal.hamiltonian), + "synthesize_identity_1q requires H_g = 0 (identity gate)", + ); + + let alpha_x = alpha_rate(&gate.noise, Pauli1::X); + let alpha_y = alpha_rate(&gate.noise, Pauli1::Y); + let alpha_z = alpha_rate(&gate.noise, Pauli1::Z); + + let tau = gate.tau_g; + let lambda_x = (alpha_y + alpha_z - alpha_x) * tau / 4.0; + let lambda_y = (alpha_x + alpha_z - alpha_y) * tau / 4.0; + let lambda_z = (alpha_x + alpha_y - alpha_z) * tau / 4.0; + + let supports = vec![ + PauliString::single(Pauli1::X), + PauliString::single(Pauli1::Y), + PauliString::single(Pauli1::Z), + ]; + let rates = vec![clip_negative(lambda_x), clip_negative(lambda_y), clip_negative(lambda_z)]; + PauliLindbladModel::new(supports, rates) +} + +/// Compute the Pauli-basis rate `alpha_b = -Tr(P_b * L(P_b)) / d` for a +/// 1-qubit Pauli. Units: 1/time. +fn alpha_rate(noise: &crate::lindbladian::Lindbladian, p: Pauli1) -> f64 { + let d = noise.d; + let p_mat = matrix::pauli_1q(p); + let l_p = noise.apply(&p_mat); + let inner = matrix::trace(&matrix::matmul(&p_mat, &l_p, d), d); + // For Hermitian P and CPTP L, alpha_b is real. + -inner.re / d as f64 +} + +fn is_zero_hamiltonian(h: &Matrix) -> bool { + h.iter().all(|c| c.re.abs() < 1e-14 && c.im.abs() < 1e-14) +} + +/// Phase 1 positivity policy: clip tiny negatives to zero; panic on large +/// negatives to surface bugs. Revisit in Phase 2. +fn clip_negative(lambda: f64) -> f64 { + if lambda < -1e-10 { + panic!("PauliLindbladModel rate unexpectedly negative: {}", lambda); + } + lambda.max(0.0) +} diff --git a/exp/pecos-lindblad/tests/identity_1q.rs b/exp/pecos-lindblad/tests/identity_1q.rs new file mode 100644 index 000000000..0c5bd63dd --- /dev/null +++ b/exp/pecos-lindblad/tests/identity_1q.rs @@ -0,0 +1,95 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Golden-fixture test for 1-qubit identity gate under amplitude damping +//! plus pure dephasing (arXiv:2502.03462 line 812, exact non-perturbative): +//! +//! lambda_x = lambda_y = (beta_down * tau_g) / 4 +//! lambda_z = (beta_phi * tau_g) / 2 + +use approx::assert_abs_diff_eq; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::{ + synthesize_identity_1q, Gate, Lindbladian, Pauli1, PauliString, +}; + +fn amplitude_damping_plus_dephasing(beta_down: f64, beta_phi: f64) -> Lindbladian { + let d = 2; + let hamiltonian = matrix::zeros(d); + let collapse: Vec<(Matrix, f64)> = vec![ + (matrix::sigma_minus(), beta_down), + (matrix::pauli_1q(Pauli1::Z), beta_phi / 2.0), + ]; + Lindbladian::new(d, hamiltonian, collapse) +} + +#[test] +fn identity_ad_plus_pd_matches_paper() { + let beta_down = 2e-4; + let beta_phi = 5e-4; + let tau_g = 50.0; + let noise = amplitude_damping_plus_dephasing(beta_down, beta_phi); + let gate = Gate::identity(1, noise, tau_g); + + let pl = synthesize_identity_1q(&gate); + + let expected_x = beta_down * tau_g / 4.0; + let expected_y = beta_down * tau_g / 4.0; + let expected_z = beta_phi * tau_g / 2.0; + + assert_abs_diff_eq!(pl.rate(&PauliString::single(Pauli1::X)), expected_x, epsilon = 1e-12); + assert_abs_diff_eq!(pl.rate(&PauliString::single(Pauli1::Y)), expected_y, epsilon = 1e-12); + assert_abs_diff_eq!(pl.rate(&PauliString::single(Pauli1::Z)), expected_z, epsilon = 1e-12); +} + +#[test] +fn identity_ad_only() { + let beta_down = 1e-3; + let tau_g = 100.0; + let noise = amplitude_damping_plus_dephasing(beta_down, 0.0); + let gate = Gate::identity(1, noise, tau_g); + + let pl = synthesize_identity_1q(&gate); + + let expected_xy = beta_down * tau_g / 4.0; + assert_abs_diff_eq!(pl.rate(&PauliString::single(Pauli1::X)), expected_xy, epsilon = 1e-12); + assert_abs_diff_eq!(pl.rate(&PauliString::single(Pauli1::Y)), expected_xy, epsilon = 1e-12); + assert_abs_diff_eq!(pl.rate(&PauliString::single(Pauli1::Z)), 0.0, epsilon = 1e-12); +} + +#[test] +fn identity_pd_only() { + let beta_phi = 7e-4; + let tau_g = 40.0; + let noise = amplitude_damping_plus_dephasing(0.0, beta_phi); + let gate = Gate::identity(1, noise, tau_g); + + let pl = synthesize_identity_1q(&gate); + + let expected_z = beta_phi * tau_g / 2.0; + assert_abs_diff_eq!(pl.rate(&PauliString::single(Pauli1::X)), 0.0, epsilon = 1e-12); + assert_abs_diff_eq!(pl.rate(&PauliString::single(Pauli1::Y)), 0.0, epsilon = 1e-12); + assert_abs_diff_eq!(pl.rate(&PauliString::single(Pauli1::Z)), expected_z, epsilon = 1e-12); +} + +#[test] +fn identity_zero_noise_gives_zero_rates() { + let noise = amplitude_damping_plus_dephasing(0.0, 0.0); + let gate = Gate::identity(1, noise, 1.0); + + let pl = synthesize_identity_1q(&gate); + + for p in [Pauli1::X, Pauli1::Y, Pauli1::Z] { + assert_abs_diff_eq!(pl.rate(&PauliString::single(p)), 0.0, epsilon = 1e-14); + } +} From 786911ed64145c6aa1e98b180c4524dc561578ef Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 10:09:13 -0600 Subject: [PATCH 014/125] Add Phase 2: 1Q X_theta synthesis via interaction frame + Simpson --- exp/pecos-lindblad/src/gate.rs | 24 +++++ exp/pecos-lindblad/src/lib.rs | 2 +- exp/pecos-lindblad/src/matrix.rs | 33 ++++++ exp/pecos-lindblad/src/synthesis.rs | 128 +++++++++++++++++------ exp/pecos-lindblad/tests/x_theta_1q.rs | 135 +++++++++++++++++++++++++ 5 files changed, 288 insertions(+), 34 deletions(-) create mode 100644 exp/pecos-lindblad/tests/x_theta_1q.rs diff --git a/exp/pecos-lindblad/src/gate.rs b/exp/pecos-lindblad/src/gate.rs index 4f4061d9d..f27b6c5a5 100644 --- a/exp/pecos-lindblad/src/gate.rs +++ b/exp/pecos-lindblad/src/gate.rs @@ -12,7 +12,10 @@ //! Gate type: ideal Hamiltonian + noise Lindbladian + duration. +use num_complex::Complex64; + use crate::lindbladian::Lindbladian; +use crate::matrix::{self, Matrix}; /// A physical gate with its ideal rotation, noise model, and duration. #[derive(Clone, Debug)] @@ -41,4 +44,25 @@ impl Gate { tau_g, } } + + /// 1-qubit arbitrary-angle X rotation: `X_theta = exp(-i theta/2 X)`. + /// Parameterized by drive frequency `omega_x` and rotation angle + /// `theta`; gate duration is `theta / omega_x`. + pub fn x_theta(omega_x: f64, theta: f64, noise: Lindbladian) -> Self { + assert!(omega_x > 0.0, "omega_x must be positive"); + assert_eq!(noise.d, 2, "x_theta is 1-qubit"); + let d = 2; + // H_g = (omega_x / 2) * X + let h_g: Matrix = + matrix::scale(&matrix::pauli_1q(crate::basis::Pauli1::X), Complex64::new(omega_x / 2.0, 0.0)); + let ideal = Lindbladian::new(d, h_g, Vec::new()); + let tau_g = theta / omega_x; + Self { + label: format!("X_{{{:.4}}}", theta), + num_qubits: 1, + ideal, + noise, + tau_g, + } + } } diff --git a/exp/pecos-lindblad/src/lib.rs b/exp/pecos-lindblad/src/lib.rs index d0f881445..a36388be4 100644 --- a/exp/pecos-lindblad/src/lib.rs +++ b/exp/pecos-lindblad/src/lib.rs @@ -32,4 +32,4 @@ pub use basis::{Pauli1, PauliString}; pub use gate::Gate; pub use lindbladian::Lindbladian; pub use pauli_lindblad::PauliLindbladModel; -pub use synthesis::synthesize_identity_1q; +pub use synthesis::{synthesize_identity_1q, synthesize_numerical_1q, DEFAULT_N_STEPS}; diff --git a/exp/pecos-lindblad/src/matrix.rs b/exp/pecos-lindblad/src/matrix.rs index 527e731f9..4b8b1e552 100644 --- a/exp/pecos-lindblad/src/matrix.rs +++ b/exp/pecos-lindblad/src/matrix.rs @@ -106,3 +106,36 @@ pub fn sigma_minus() -> Matrix { let o = Complex64::new(1.0, 0.0); vec![z, z, o, z] } + +/// Matrix exponential `exp(-i * H * t)` for a 2x2 traceless Hermitian H. +/// Uses the Bloch form: `exp(-i H t) = cos(r t) I - i sin(r t) H / r` +/// where `r = sqrt(c_x^2 + c_y^2 + c_z^2)` is the Pauli-decomposition norm. +/// Panics if `H` has nonzero trace (use a dedicated impl for those cases). +pub fn exp_minus_i_h_t_1q(h: &Matrix, t: f64) -> Matrix { + assert_eq!(h.len(), 4, "exp_minus_i_h_t_1q requires a 2x2 matrix"); + // Check Hermitian (tolerant). + let h00 = h[0]; + let h01 = h[1]; + let h10 = h[2]; + let h11 = h[3]; + assert!(h00.im.abs() < 1e-12 && h11.im.abs() < 1e-12, "H not Hermitian (diagonal)"); + assert!((h10 - h01.conj()).norm() < 1e-12, "H not Hermitian (off-diagonal)"); + let tr = (h00 + h11).re; + assert!(tr.abs() < 1e-12, "H must be traceless; got trace = {}", tr); + + // Pauli decomposition: H = c_x X + c_y Y + c_z Z. + let c_x = h01.re; + let c_y = -h01.im; // since H_{01} = c_x - i c_y + let c_z = (h00.re - h11.re) * 0.5; + + let r = (c_x * c_x + c_y * c_y + c_z * c_z).sqrt(); + if r < 1e-15 { + return identity(2); + } + let c = (r * t).cos(); + let s = (r * t).sin() / r; + let minus_i_s = Complex64::new(0.0, -s); + // result = c * I - i s * H + let i2 = identity(2); + add(&scale(&i2, Complex64::new(c, 0.0)), &scale(h, minus_i_s)) +} diff --git a/exp/pecos-lindblad/src/synthesis.rs b/exp/pecos-lindblad/src/synthesis.rs index 083f58311..4c3f97447 100644 --- a/exp/pecos-lindblad/src/synthesis.rs +++ b/exp/pecos-lindblad/src/synthesis.rs @@ -10,38 +10,111 @@ // or implied. See the License for the specific language governing permissions and limitations under // the License. -//! Phase 1: numerical Pauli-Lindblad synthesis for identity gates. +//! Phase 1-2: numerical Pauli-Lindblad synthesis for 1-qubit gates. //! -//! For an identity gate (`H_g = 0`) the interaction-frame Lindbladian is -//! time-independent and `Omega_1 = L * tau_g` is exact to first order in the -//! Magnus expansion. For 1-qubit identity with amplitude damping plus pure -//! dephasing the first-order result is already **exact and -//! non-perturbative** (paper arXiv:2502.03462 line 812); see -//! `design/lindblad_magnus_algorithm.md` section 3. +//! - `synthesize_identity_1q`: fast path for `H_g = 0` (Phase 1; identity +//! under amplitude damping + pure dephasing is exact, non-perturbative). +//! - `synthesize_numerical_1q`: general 1-qubit path (Phase 2) via +//! interaction-frame transform + Simpson's rule on Omega_1. +//! +//! See `design/lindblad_magnus_algorithm.md` for the math spec and paper +//! arXiv:2502.03462 for closed-form fixtures. + +use num_complex::Complex64; use crate::basis::{Pauli1, PauliString}; use crate::gate::Gate; +use crate::lindbladian::Lindbladian; use crate::matrix::{self, Matrix}; use crate::pauli_lindblad::PauliLindbladModel; -/// Synthesize a 1-qubit Pauli-Lindblad model from an identity gate. -/// Supports are `{X, Y, Z}`; rates come from the linear system -/// `alpha_b * tau_g = 2 sum_{k != I} lambda_k * _sp`. +const PHASE1_PAULIS: [Pauli1; 3] = [Pauli1::X, Pauli1::Y, Pauli1::Z]; + +/// Default number of Simpson intervals for 1-qubit time integration. +/// Composite Simpson's 1/3 rule, order-4 accurate. 1024 gives ~1e-12 for +/// smooth integrands on a bounded interval (sinusoidal at frequency +/// `omega_x` up to a few cycles). +pub const DEFAULT_N_STEPS: usize = 1024; + +/// Synthesize a 1-qubit Pauli-Lindblad model from an identity gate. Fast +/// path: identity gate (`H_g = 0`) => interaction-frame Lindbladian is +/// constant and `Omega_1 = L * tau_g`. pub fn synthesize_identity_1q(gate: &Gate) -> PauliLindbladModel { assert_eq!(gate.num_qubits, 1, "synthesize_identity_1q requires 1 qubit"); assert!( - is_zero_hamiltonian(&gate.ideal.hamiltonian), - "synthesize_identity_1q requires H_g = 0 (identity gate)", + is_zero_matrix(&gate.ideal.hamiltonian), + "synthesize_identity_1q requires H_g = 0", ); + let tau = gate.tau_g; + let alphas = PHASE1_PAULIS.map(|p| constant_alpha(&gate.noise, p) * tau); + model_from_alphas(alphas) +} + +/// Synthesize a 1-qubit Pauli-Lindblad model from an arbitrary 1-qubit +/// gate via Simpson's rule on `Omega_1 = int_0^{tau_g} L_I(t) dt`. Works +/// for identity (reduces to the Phase 1 result) and for gates like +/// `X_theta`, `Y_theta`, `Z_theta`. +pub fn synthesize_numerical_1q(gate: &Gate, n_steps: usize) -> PauliLindbladModel { + assert_eq!(gate.num_qubits, 1, "synthesize_numerical_1q requires 1 qubit"); + assert!(n_steps >= 2 && n_steps % 2 == 0, "n_steps must be even and >= 2, got {}", n_steps); + let alphas = PHASE1_PAULIS.map(|p| integrated_alpha_1q(gate, p, n_steps)); + model_from_alphas(alphas) +} - let alpha_x = alpha_rate(&gate.noise, Pauli1::X); - let alpha_y = alpha_rate(&gate.noise, Pauli1::Y); - let alpha_z = alpha_rate(&gate.noise, Pauli1::Z); +/// `alpha_b = -Tr(P_b L(P_b)) / d` for time-independent L. Units: 1/time. +fn constant_alpha(noise: &Lindbladian, p: Pauli1) -> f64 { + let d = noise.d; + let p_mat = matrix::pauli_1q(p); + let l_p = noise.apply(&p_mat); + let inner = matrix::trace(&matrix::matmul(&p_mat, &l_p, d), d); + -inner.re / d as f64 +} +/// Integrated `alpha_b * tau_g = -Tr(P_b * Omega_1(P_b)) / d` via Simpson's +/// rule on `[0, tau_g]`. +fn integrated_alpha_1q(gate: &Gate, p: Pauli1, n_steps: usize) -> f64 { + let d = 2; + let p_mat = matrix::pauli_1q(p); + let h_g = &gate.ideal.hamiltonian; let tau = gate.tau_g; - let lambda_x = (alpha_y + alpha_z - alpha_x) * tau / 4.0; - let lambda_y = (alpha_x + alpha_z - alpha_y) * tau / 4.0; - let lambda_z = (alpha_x + alpha_y - alpha_z) * tau / 4.0; + let h_step = tau / n_steps as f64; + + // integrand(t) = -Tr(P_b * L_I(t)(P_b)).re / d + // = -Tr(P_b * U_g^†(t) L(U_g(t) P_b U_g^†(t)) U_g(t)) / d + let integrand = |t: f64| -> f64 { + let u = matrix::exp_minus_i_h_t_1q(h_g, t); + let u_dag = matrix::dag(&u, d); + // rotated = U_g(t) P_b U_g^†(t) + let rotated = matrix::matmul(&matrix::matmul(&u, &p_mat, d), &u_dag, d); + // L applied to rotated + let l_rotated = gate.noise.apply(&rotated); + // Conjugate back: U_g^†(t) L(rotated) U_g(t) + let l_i_pb = matrix::matmul(&matrix::matmul(&u_dag, &l_rotated, d), &u, d); + // -Tr(P_b * L_I(t)(P_b)) / d + let inner = matrix::trace(&matrix::matmul(&p_mat, &l_i_pb, d), d); + -inner.re / d as f64 + }; + + // Composite Simpson's 1/3 rule. Weights: 1, 4, 2, 4, 2, ..., 4, 1. + let mut s = integrand(0.0) + integrand(tau); + for k in 1..n_steps { + let t = k as f64 * h_step; + let w = if k % 2 == 1 { 4.0 } else { 2.0 }; + s += w * integrand(t); + } + s * h_step / 3.0 +} + +fn model_from_alphas(alphas: [f64; 3]) -> PauliLindbladModel { + // alphas = [alpha_X * tau_g, alpha_Y * tau_g, alpha_Z * tau_g]. + // Linear solve of alpha_b = 2 sum_{k != I} lambda_k _sp: + // alpha_X = 2(lambda_Y + lambda_Z) + // alpha_Y = 2(lambda_X + lambda_Z) + // alpha_Z = 2(lambda_X + lambda_Y) + let [ax, ay, az] = alphas; + let lambda_x = (ay + az - ax) / 4.0; + let lambda_y = (ax + az - ay) / 4.0; + let lambda_z = (ax + ay - az) / 4.0; let supports = vec![ PauliString::single(Pauli1::X), @@ -52,25 +125,14 @@ pub fn synthesize_identity_1q(gate: &Gate) -> PauliLindbladModel { PauliLindbladModel::new(supports, rates) } -/// Compute the Pauli-basis rate `alpha_b = -Tr(P_b * L(P_b)) / d` for a -/// 1-qubit Pauli. Units: 1/time. -fn alpha_rate(noise: &crate::lindbladian::Lindbladian, p: Pauli1) -> f64 { - let d = noise.d; - let p_mat = matrix::pauli_1q(p); - let l_p = noise.apply(&p_mat); - let inner = matrix::trace(&matrix::matmul(&p_mat, &l_p, d), d); - // For Hermitian P and CPTP L, alpha_b is real. - -inner.re / d as f64 -} - -fn is_zero_hamiltonian(h: &Matrix) -> bool { - h.iter().all(|c| c.re.abs() < 1e-14 && c.im.abs() < 1e-14) +fn is_zero_matrix(m: &Matrix) -> bool { + m.iter().all(|c: &Complex64| c.re.abs() < 1e-14 && c.im.abs() < 1e-14) } /// Phase 1 positivity policy: clip tiny negatives to zero; panic on large -/// negatives to surface bugs. Revisit in Phase 2. +/// negatives so bugs surface. Revisit in Phase 3 with per-user policy. fn clip_negative(lambda: f64) -> f64 { - if lambda < -1e-10 { + if lambda < -1e-8 { panic!("PauliLindbladModel rate unexpectedly negative: {}", lambda); } lambda.max(0.0) diff --git a/exp/pecos-lindblad/tests/x_theta_1q.rs b/exp/pecos-lindblad/tests/x_theta_1q.rs new file mode 100644 index 000000000..57ed3e0d8 --- /dev/null +++ b/exp/pecos-lindblad/tests/x_theta_1q.rs @@ -0,0 +1,135 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Parity test: 1-qubit X_theta gate under amplitude damping + pure +//! dephasing vs closed-form leading-order results from arXiv:2502.03462 +//! eqs. 869-874 (appendix SubApp:X_th+AD+PD). +//! +//! Paper closed forms (lambda_k are dimensionless, integrated over the gate): +//! lambda_x = (theta / 4) * (beta_down / omega_x) +//! lambda_y = ((2 theta + sin 2 theta) / 16) * (beta_down / omega_x) +//! + ((2 theta - sin 2 theta) / 8) * (beta_phi / omega_x) +//! lambda_z = ((2 theta - sin 2 theta) / 16) * (beta_down / omega_x) +//! + ((2 theta + sin 2 theta) / 8) * (beta_phi / omega_x) +//! +//! The paper's approximation is "leading order in beta/omega"; at +//! `beta/omega ~ 1e-2` deviation should be ~`O(1e-5)` per +//! Appendix `App:LindPertPrecision` (line 1078). + +use approx::assert_abs_diff_eq; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::{ + synthesize_numerical_1q, Gate, Lindbladian, Pauli1, PauliString, + DEFAULT_N_STEPS, +}; + +fn ad_plus_pd_noise(beta_down: f64, beta_phi: f64) -> Lindbladian { + let d = 2; + let hamiltonian = matrix::zeros(d); + let collapse: Vec<(Matrix, f64)> = vec![ + (matrix::sigma_minus(), beta_down), + (matrix::pauli_1q(Pauli1::Z), beta_phi / 2.0), + ]; + Lindbladian::new(d, hamiltonian, collapse) +} + +fn paper_closed_form(theta: f64, omega_x: f64, beta_down: f64, beta_phi: f64) -> (f64, f64, f64) { + let two_t = 2.0 * theta; + let sin_2t = two_t.sin(); + let lambda_x = (theta / 4.0) * (beta_down / omega_x); + let lambda_y = ((two_t + sin_2t) / 16.0) * (beta_down / omega_x) + + ((two_t - sin_2t) / 8.0) * (beta_phi / omega_x); + let lambda_z = ((two_t - sin_2t) / 16.0) * (beta_down / omega_x) + + ((two_t + sin_2t) / 8.0) * (beta_phi / omega_x); + (lambda_x, lambda_y, lambda_z) +} + +fn run_and_compare(theta: f64, omega_x: f64, beta_down: f64, beta_phi: f64, tol: f64) { + let noise = ad_plus_pd_noise(beta_down, beta_phi); + let gate = Gate::x_theta(omega_x, theta, noise); + let pl = synthesize_numerical_1q(&gate, DEFAULT_N_STEPS); + + let (expected_x, expected_y, expected_z) = + paper_closed_form(theta, omega_x, beta_down, beta_phi); + + let got_x = pl.rate(&PauliString::single(Pauli1::X)); + let got_y = pl.rate(&PauliString::single(Pauli1::Y)); + let got_z = pl.rate(&PauliString::single(Pauli1::Z)); + + assert_abs_diff_eq!(got_x, expected_x, epsilon = tol); + assert_abs_diff_eq!(got_y, expected_y, epsilon = tol); + assert_abs_diff_eq!(got_z, expected_z, epsilon = tol); +} + +#[test] +fn x_theta_ad_plus_pd_pi_over_4() { + // Weak noise => numerical integrand matches leading-order closed form + // to within ~O(beta^2 / omega^2). Use beta/omega = 1e-4 => tol ~1e-8. + let omega_x = 1.0; + let beta_down = 1e-4; + let beta_phi = 2e-4; + let theta = std::f64::consts::FRAC_PI_4; + run_and_compare(theta, omega_x, beta_down, beta_phi, 1e-8); +} + +#[test] +fn x_theta_ad_plus_pd_pi_over_2() { + let omega_x = 1.0; + let beta_down = 1e-4; + let beta_phi = 5e-5; + let theta = std::f64::consts::FRAC_PI_2; + run_and_compare(theta, omega_x, beta_down, beta_phi, 1e-8); +} + +#[test] +fn x_theta_ad_only_pi_over_3() { + // lambda_x = (theta/4)(beta_down/omega_x), lambda_y and lambda_z from + // beta_down only. + let omega_x = 2.0; + let beta_down = 3e-4; + let beta_phi = 0.0; + let theta = std::f64::consts::FRAC_PI_3; + run_and_compare(theta, omega_x, beta_down, beta_phi, 1e-8); +} + +#[test] +fn x_theta_pd_only_pi_over_2() { + // lambda_x = 0 (no AD). + let omega_x = 1.0; + let beta_down = 0.0; + let beta_phi = 4e-4; + let theta = std::f64::consts::FRAC_PI_2; + run_and_compare(theta, omega_x, beta_down, beta_phi, 1e-8); +} + +#[test] +fn numerical_1q_reduces_to_identity() { + // synthesize_numerical_1q on an identity gate (H_g = 0) should match + // the fast-path identity synthesis to high precision. Exercises the + // time-integral path on a constant integrand. + use pecos_lindblad::synthesize_identity_1q; + + let beta_down = 1e-4; + let beta_phi = 3e-4; + let tau_g = 50.0; + let noise = ad_plus_pd_noise(beta_down, beta_phi); + let gate = Gate::identity(1, noise, tau_g); + + let fast = synthesize_identity_1q(&gate); + let numerical = synthesize_numerical_1q(&gate, DEFAULT_N_STEPS); + + for p in [Pauli1::X, Pauli1::Y, Pauli1::Z] { + let key = PauliString::single(p); + assert_abs_diff_eq!(fast.rate(&key), numerical.rate(&key), epsilon = 1e-12); + } +} From 707e21da7a49b357425fb2b935b229576a1b84ed Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 10:20:42 -0600 Subject: [PATCH 015/125] Correct Walsh-Hadamard inversion sign in algorithm spec --- design/lindblad_magnus_algorithm.md | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/design/lindblad_magnus_algorithm.md b/design/lindblad_magnus_algorithm.md index c384e8d99..7355a1c97 100644 --- a/design/lindblad_magnus_algorithm.md +++ b/design/lindblad_magnus_algorithm.md @@ -82,10 +82,18 @@ L_eff = (1/tau_g) * sum_{n=1..N} Omega_n // Step 4 -- Pauli twirl projection // Twirled generator is diagonal in Pauli basis. // Diagonal coeff: alpha_b = -(1/d) tr( P_b * L_eff(P_b) ) -// Rates recovered via Walsh-Hadamard on {0,1}^{2n} -// (2201.09866 eq. (1)): -// alpha_b = 2 sum_k lambda_k _sp -// lambda_k = (1/4^n) sum_b (-1)^{_sp} (alpha_b / 2) +// (alpha_b is a *rate* = 1/time; its integrated form is alpha_b * tau_g.) +// Rates recovered via Walsh-Hadamard on {0,1}^{2n} (2201.09866 eq. (1)): +// alpha_b = 2 sum_k lambda_k _sp // forward map +// lambda_k = -(1/4^n) sum_b (-1)^{_sp} alpha_b // for k != I +// lambda_I = 0 (by convention; not a physical rate) +// +// Derivation sketch: let W_{bk} = (-1)^{_sp}, T = sum_k lambda_k. +// Then (W lambda)_b = T - alpha_b (since _sp = (1 - W_{bk})/2). W is +// self-inverse up to a factor of 4^n, so applying W and using that +// sum_b (-1)^{_sp} vanishes for k != I gives the formula above. +// For the 1-qubit case this collapses to the direct linear solve +// lambda_X = (alpha_Y + alpha_Z - alpha_X) / 4 (etc. by symmetry). // Step 5 -- Dyson cross-check (paper eq. 13) // T exp( int L_I ) = I + Omega_1 + Omega_2 + 1/2 Omega_1^2 + O(L_I^3) From 4a396ea12be99fabe0240cf7b8526b6987b7b075 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 10:26:34 -0600 Subject: [PATCH 016/125] Add Phase 3: n-qubit synthesis with Walsh-Hadamard + CZ_theta test --- exp/pecos-lindblad/src/basis.rs | 100 +++++++++++++ exp/pecos-lindblad/src/gate.rs | 21 +++ exp/pecos-lindblad/src/lib.rs | 4 +- exp/pecos-lindblad/src/matrix.rs | 81 ++++++++++- exp/pecos-lindblad/src/pauli_lindblad.rs | 21 +-- exp/pecos-lindblad/src/synthesis.rs | 102 +++++++------ exp/pecos-lindblad/tests/cz_theta_2q.rs | 174 +++++++++++++++++++++++ 7 files changed, 439 insertions(+), 64 deletions(-) create mode 100644 exp/pecos-lindblad/tests/cz_theta_2q.rs diff --git a/exp/pecos-lindblad/src/basis.rs b/exp/pecos-lindblad/src/basis.rs index d7e72298a..197bcf946 100644 --- a/exp/pecos-lindblad/src/basis.rs +++ b/exp/pecos-lindblad/src/basis.rs @@ -43,6 +43,31 @@ impl Pauli1 { Pauli1::Z => 'Z', } } + + /// Pauli multiplication ignoring global phase. Returns the Hermitian + /// Pauli factor: XY -> Z (phase `i` dropped), etc. Safe for our use in + /// `PauliLindbladModel::sample`, where rates are carried by commuting + /// structure and phases cancel in `P rho P^dag` style actions. + pub fn multiply(self, other: Pauli1) -> Pauli1 { + use Pauli1::*; + match (self, other) { + (I, x) | (x, I) => x, + (X, X) | (Y, Y) | (Z, Z) => I, + (X, Y) | (Y, X) => Z, + (Y, Z) | (Z, Y) => X, + (X, Z) | (Z, X) => Y, + } + } + + /// 1 if two single-qubit Paulis anticommute, 0 if they commute. + pub fn anticommutes_with(self, other: Pauli1) -> u8 { + use Pauli1::*; + match (self, other) { + (I, _) | (_, I) => 0, + (a, b) if a == b => 0, + _ => 1, + } + } } /// Multi-qubit Pauli string. Index 0 = leftmost factor. @@ -66,6 +91,51 @@ impl PauliString { pub fn weight(&self) -> usize { self.0.iter().filter(|&&p| p != Pauli1::I).count() } + + /// Is this the identity string? + pub fn is_identity(&self) -> bool { + self.weight() == 0 + } + + /// Elementwise product with global phase dropped. See + /// [`Pauli1::multiply`]. + pub fn multiply(&self, other: &PauliString) -> PauliString { + assert_eq!(self.num_qubits(), other.num_qubits(), "ragged multiply"); + PauliString(self.0.iter().zip(&other.0).map(|(a, b)| a.multiply(*b)).collect()) + } + + /// Symplectic product `_sp`: 1 if the two strings + /// anticommute, 0 if they commute. Equal to (sum of pairwise + /// anticommutes) mod 2. + pub fn symplectic_product(&self, other: &PauliString) -> u8 { + assert_eq!(self.num_qubits(), other.num_qubits(), "ragged symplectic"); + self.0.iter().zip(&other.0).map(|(a, b)| a.anticommutes_with(*b)).sum::() & 1 + } + + /// Enumerate all non-identity Pauli strings on `n` qubits. Length + /// 4^n - 1 = 3, 15, 63, ... + pub fn enumerate_nonidentity(n: usize) -> Vec { + let total = 1usize << (2 * n); + (1..total) + .map(|idx| { + // idx in base 4: two bits per qubit, low bits = rightmost factor + let mut qs = Vec::with_capacity(n); + for q in 0..n { + let shift = 2 * (n - 1 - q); + let bits = (idx >> shift) & 0b11; + let p = match bits { + 0 => Pauli1::I, + 1 => Pauli1::X, + 2 => Pauli1::Y, + 3 => Pauli1::Z, + _ => unreachable!(), + }; + qs.push(p); + } + PauliString(qs) + }) + .collect() + } } impl fmt::Display for PauliString { @@ -100,4 +170,34 @@ mod tests { let s = PauliString::from_str("IXI").unwrap(); assert_eq!(s.weight(), 1); } + + #[test] + fn symplectic_product_2q() { + let ix = PauliString::from_str("IX").unwrap(); + let iz = PauliString::from_str("IZ").unwrap(); + let zx = PauliString::from_str("ZX").unwrap(); + assert_eq!(ix.symplectic_product(&iz), 1); // X,Z anticommute on right + assert_eq!(ix.symplectic_product(&ix), 0); + assert_eq!(zx.symplectic_product(&iz), 1); // X,Z on right anticommute + assert_eq!(zx.symplectic_product(&zx), 0); + } + + #[test] + fn enumerate_1q_gives_xyz() { + let all = PauliString::enumerate_nonidentity(1); + assert_eq!(all.len(), 3); + assert_eq!(all[0], PauliString::from_str("X").unwrap()); + assert_eq!(all[1], PauliString::from_str("Y").unwrap()); + assert_eq!(all[2], PauliString::from_str("Z").unwrap()); + } + + #[test] + fn enumerate_2q_gives_15() { + let all = PauliString::enumerate_nonidentity(2); + assert_eq!(all.len(), 15); + // First should be IX (idx 1 = 0b01 = 0|X). + assert_eq!(all[0], PauliString::from_str("IX").unwrap()); + // Last should be ZZ (idx 15 = 0b1111 = Z|Z). + assert_eq!(all[14], PauliString::from_str("ZZ").unwrap()); + } } diff --git a/exp/pecos-lindblad/src/gate.rs b/exp/pecos-lindblad/src/gate.rs index f27b6c5a5..2953ec7a4 100644 --- a/exp/pecos-lindblad/src/gate.rs +++ b/exp/pecos-lindblad/src/gate.rs @@ -65,4 +65,25 @@ impl Gate { tau_g, } } + + /// 2-qubit arbitrary-angle CZ rotation: + /// `CZ_theta = exp(-i (theta/2) (II - IZ - ZI + ZZ))`. + /// In computational basis `H_g = diag(0, 0, 0, 2 * omega_cz)`. + /// Reference: arXiv:2502.03462 lines 885-891. + pub fn cz_theta(omega_cz: f64, theta: f64, noise: Lindbladian) -> Self { + assert!(omega_cz > 0.0, "omega_cz must be positive"); + assert_eq!(noise.d, 4, "cz_theta is 2-qubit"); + let d = 4; + let mut h_g = matrix::zeros(d); + h_g[3 * d + 3] = Complex64::new(2.0 * omega_cz, 0.0); + let ideal = Lindbladian::new(d, h_g, Vec::new()); + let tau_g = theta / omega_cz; + Self { + label: format!("CZ_{{{:.4}}}", theta), + num_qubits: 2, + ideal, + noise, + tau_g, + } + } } diff --git a/exp/pecos-lindblad/src/lib.rs b/exp/pecos-lindblad/src/lib.rs index a36388be4..5b5740bf7 100644 --- a/exp/pecos-lindblad/src/lib.rs +++ b/exp/pecos-lindblad/src/lib.rs @@ -32,4 +32,6 @@ pub use basis::{Pauli1, PauliString}; pub use gate::Gate; pub use lindbladian::Lindbladian; pub use pauli_lindblad::PauliLindbladModel; -pub use synthesis::{synthesize_identity_1q, synthesize_numerical_1q, DEFAULT_N_STEPS}; +pub use synthesis::{ + synthesize_identity_1q, synthesize_numerical, synthesize_numerical_1q, DEFAULT_N_STEPS, +}; diff --git a/exp/pecos-lindblad/src/matrix.rs b/exp/pecos-lindblad/src/matrix.rs index 4b8b1e552..732c45cf8 100644 --- a/exp/pecos-lindblad/src/matrix.rs +++ b/exp/pecos-lindblad/src/matrix.rs @@ -18,7 +18,7 @@ use num_complex::Complex64; -use crate::basis::Pauli1; +use crate::basis::{Pauli1, PauliString}; pub type Matrix = Vec; @@ -107,12 +107,85 @@ pub fn sigma_minus() -> Matrix { vec![z, z, o, z] } +/// Kronecker product of `a` (da x da) and `b` (db x db). Result is +/// `(da * db) x (da * db)`. +pub fn kron(a: &Matrix, b: &Matrix, da: usize, db: usize) -> Matrix { + let d = da * db; + let mut out = zeros(d); + for i in 0..da { + for j in 0..da { + let aij = a[i * da + j]; + if aij == Complex64::new(0.0, 0.0) { + continue; + } + for k in 0..db { + for l in 0..db { + let bkl = b[k * db + l]; + let row = i * db + k; + let col = j * db + l; + out[row * d + col] = aij * bkl; + } + } + } + } + out +} + +/// Matrix representation of a multi-qubit Pauli string (tensor-product +/// of 2x2 Pauli matrices, left-to-right). +pub fn pauli_string_mat(ps: &PauliString) -> Matrix { + assert!(!ps.0.is_empty(), "empty PauliString"); + let mut acc = pauli_1q(ps.0[0]); + let mut d = 2; + for p in ps.0.iter().skip(1) { + acc = kron(&acc, &pauli_1q(*p), d, 2); + d *= 2; + } + acc +} + +/// Check whether a d x d matrix is (numerically) diagonal. +pub fn is_diagonal(m: &Matrix, d: usize, tol: f64) -> bool { + for i in 0..d { + for j in 0..d { + if i == j { + continue; + } + if m[i * d + j].norm() > tol { + return false; + } + } + } + true +} + +/// `exp(-i * H * t)` for a Hermitian `H`. Dispatches: +/// - If `H` is diagonal -> elementwise exp (works for any `d`). +/// - Else if `d == 2` and `H` is traceless -> Bloch form via +/// [`exp_minus_i_h_t_1q_traceless`]. +/// - Else panics with "not implemented". Future work: add +/// eigendecomposition path for `d > 2` non-diagonal. +pub fn exp_minus_i_h_t(h: &Matrix, d: usize, t: f64) -> Matrix { + if is_diagonal(h, d, 1e-14) { + let mut u = zeros(d); + for i in 0..d { + let arg = Complex64::new(0.0, -h[i * d + i].re * t); + u[i * d + i] = arg.exp(); + } + return u; + } + if d == 2 { + return exp_minus_i_h_t_1q_traceless(h, t); + } + panic!("exp_minus_i_h_t: non-diagonal and d={} > 2 not implemented", d); +} + /// Matrix exponential `exp(-i * H * t)` for a 2x2 traceless Hermitian H. /// Uses the Bloch form: `exp(-i H t) = cos(r t) I - i sin(r t) H / r` /// where `r = sqrt(c_x^2 + c_y^2 + c_z^2)` is the Pauli-decomposition norm. -/// Panics if `H` has nonzero trace (use a dedicated impl for those cases). -pub fn exp_minus_i_h_t_1q(h: &Matrix, t: f64) -> Matrix { - assert_eq!(h.len(), 4, "exp_minus_i_h_t_1q requires a 2x2 matrix"); +/// Panics if `H` has nonzero trace. +pub fn exp_minus_i_h_t_1q_traceless(h: &Matrix, t: f64) -> Matrix { + assert_eq!(h.len(), 4, "requires a 2x2 matrix"); // Check Hermitian (tolerant). let h00 = h[0]; let h01 = h[1]; diff --git a/exp/pecos-lindblad/src/pauli_lindblad.rs b/exp/pecos-lindblad/src/pauli_lindblad.rs index 362b7c192..2efd9d93b 100644 --- a/exp/pecos-lindblad/src/pauli_lindblad.rs +++ b/exp/pecos-lindblad/src/pauli_lindblad.rs @@ -47,30 +47,15 @@ impl PauliLindbladModel { pub fn sample(&self, t_scale: f64, rng: &mut impl Rng) -> PauliString { assert!(!self.supports.is_empty(), "cannot sample empty model"); let n = self.supports[0].num_qubits(); - let mut acc = vec![Pauli1::I; n]; + let mut acc = PauliString(vec![Pauli1::I; n]); for (support, &lambda) in self.supports.iter().zip(&self.rates) { assert_eq!(support.num_qubits(), n, "ragged supports"); let p_flip = 0.5 * (1.0 - (-2.0 * lambda * t_scale).exp()); if rng.random_range(0.0..1.0) < p_flip { - for (a, b) in acc.iter_mut().zip(&support.0) { - *a = pauli_multiply(*a, *b); - } + acc = acc.multiply(support); } } - PauliString(acc) - } -} - -/// 1-qubit Pauli multiplication (ignoring phase -- supports are Hermitian -/// so phase cancels in `P rho P^dag` style actions). -fn pauli_multiply(a: Pauli1, b: Pauli1) -> Pauli1 { - use Pauli1::*; - match (a, b) { - (I, x) | (x, I) => x, - (X, X) | (Y, Y) | (Z, Z) => I, - (X, Y) | (Y, X) => Z, - (Y, Z) | (Z, Y) => X, - (X, Z) | (Z, X) => Y, + acc } } diff --git a/exp/pecos-lindblad/src/synthesis.rs b/exp/pecos-lindblad/src/synthesis.rs index 4c3f97447..1361c98d2 100644 --- a/exp/pecos-lindblad/src/synthesis.rs +++ b/exp/pecos-lindblad/src/synthesis.rs @@ -10,12 +10,16 @@ // or implied. See the License for the specific language governing permissions and limitations under // the License. -//! Phase 1-2: numerical Pauli-Lindblad synthesis for 1-qubit gates. +//! Phases 1-3: numerical Pauli-Lindblad synthesis for arbitrary-qubit +//! gates via interaction-frame transform + Simpson's rule + Walsh-Hadamard +//! inversion. //! -//! - `synthesize_identity_1q`: fast path for `H_g = 0` (Phase 1; identity -//! under amplitude damping + pure dephasing is exact, non-perturbative). -//! - `synthesize_numerical_1q`: general 1-qubit path (Phase 2) via -//! interaction-frame transform + Simpson's rule on Omega_1. +//! Entry points: +//! - [`synthesize_identity_1q`]: fast path for 1Q `H_g = 0` (Phase 1; +//! exact + non-perturbative under AD + PD). +//! - [`synthesize_numerical_1q`]: 1Q, general `H_g`, Simpson integrand. +//! - [`synthesize_numerical`]: n-qubit, general `H_g`, Simpson integrand, +//! Walsh-Hadamard rate recovery. //! //! See `design/lindblad_magnus_algorithm.md` for the math spec and paper //! arXiv:2502.03462 for closed-form fixtures. @@ -30,15 +34,15 @@ use crate::pauli_lindblad::PauliLindbladModel; const PHASE1_PAULIS: [Pauli1; 3] = [Pauli1::X, Pauli1::Y, Pauli1::Z]; -/// Default number of Simpson intervals for 1-qubit time integration. -/// Composite Simpson's 1/3 rule, order-4 accurate. 1024 gives ~1e-12 for -/// smooth integrands on a bounded interval (sinusoidal at frequency -/// `omega_x` up to a few cycles). +/// Default number of Simpson intervals for time integration. Composite +/// Simpson's 1/3 rule, order-4 accurate. 1024 gives ~1e-12 for smooth +/// integrands on a bounded interval (sinusoidal at gate frequency up to a +/// few cycles). pub const DEFAULT_N_STEPS: usize = 1024; /// Synthesize a 1-qubit Pauli-Lindblad model from an identity gate. Fast /// path: identity gate (`H_g = 0`) => interaction-frame Lindbladian is -/// constant and `Omega_1 = L * tau_g`. +/// constant and `Omega_1 = L * tau_g`, so no time integration needed. pub fn synthesize_identity_1q(gate: &Gate) -> PauliLindbladModel { assert_eq!(gate.num_qubits, 1, "synthesize_identity_1q requires 1 qubit"); assert!( @@ -46,8 +50,10 @@ pub fn synthesize_identity_1q(gate: &Gate) -> PauliLindbladModel { "synthesize_identity_1q requires H_g = 0", ); let tau = gate.tau_g; - let alphas = PHASE1_PAULIS.map(|p| constant_alpha(&gate.noise, p) * tau); - model_from_alphas(alphas) + let paulis: Vec = PHASE1_PAULIS.iter().map(|&p| PauliString::single(p)).collect(); + let alphas: Vec = + PHASE1_PAULIS.iter().map(|&p| constant_alpha(&gate.noise, p) * tau).collect(); + model_from_alphas_walsh(paulis, alphas, 1) } /// Synthesize a 1-qubit Pauli-Lindblad model from an arbitrary 1-qubit @@ -56,9 +62,20 @@ pub fn synthesize_identity_1q(gate: &Gate) -> PauliLindbladModel { /// `X_theta`, `Y_theta`, `Z_theta`. pub fn synthesize_numerical_1q(gate: &Gate, n_steps: usize) -> PauliLindbladModel { assert_eq!(gate.num_qubits, 1, "synthesize_numerical_1q requires 1 qubit"); + synthesize_numerical(gate, n_steps) +} + +/// Synthesize a Pauli-Lindblad model from an arbitrary gate. Enumerates all +/// non-identity Paulis on `gate.num_qubits`, integrates `alpha_b * tau_g` +/// for each via Simpson's rule on the interaction-frame Lindbladian, and +/// inverts via Walsh-Hadamard. +pub fn synthesize_numerical(gate: &Gate, n_steps: usize) -> PauliLindbladModel { assert!(n_steps >= 2 && n_steps % 2 == 0, "n_steps must be even and >= 2, got {}", n_steps); - let alphas = PHASE1_PAULIS.map(|p| integrated_alpha_1q(gate, p, n_steps)); - model_from_alphas(alphas) + let n = gate.num_qubits; + let paulis = PauliString::enumerate_nonidentity(n); + let alphas: Vec = + paulis.iter().map(|p| integrated_alpha(gate, p, n_steps)).collect(); + model_from_alphas_walsh(paulis, alphas, n) } /// `alpha_b = -Tr(P_b L(P_b)) / d` for time-independent L. Units: 1/time. @@ -71,10 +88,12 @@ fn constant_alpha(noise: &Lindbladian, p: Pauli1) -> f64 { } /// Integrated `alpha_b * tau_g = -Tr(P_b * Omega_1(P_b)) / d` via Simpson's -/// rule on `[0, tau_g]`. -fn integrated_alpha_1q(gate: &Gate, p: Pauli1, n_steps: usize) -> f64 { - let d = 2; - let p_mat = matrix::pauli_1q(p); +/// rule on `[0, tau_g]`. Works for any `n_qubits`. +fn integrated_alpha(gate: &Gate, p: &PauliString, n_steps: usize) -> f64 { + let n = gate.num_qubits; + assert_eq!(p.num_qubits(), n); + let d = 1usize << n; + let p_mat = matrix::pauli_string_mat(p); let h_g = &gate.ideal.hamiltonian; let tau = gate.tau_g; let h_step = tau / n_steps as f64; @@ -82,15 +101,11 @@ fn integrated_alpha_1q(gate: &Gate, p: Pauli1, n_steps: usize) -> f64 { // integrand(t) = -Tr(P_b * L_I(t)(P_b)).re / d // = -Tr(P_b * U_g^†(t) L(U_g(t) P_b U_g^†(t)) U_g(t)) / d let integrand = |t: f64| -> f64 { - let u = matrix::exp_minus_i_h_t_1q(h_g, t); + let u = matrix::exp_minus_i_h_t(h_g, d, t); let u_dag = matrix::dag(&u, d); - // rotated = U_g(t) P_b U_g^†(t) let rotated = matrix::matmul(&matrix::matmul(&u, &p_mat, d), &u_dag, d); - // L applied to rotated let l_rotated = gate.noise.apply(&rotated); - // Conjugate back: U_g^†(t) L(rotated) U_g(t) let l_i_pb = matrix::matmul(&matrix::matmul(&u_dag, &l_rotated, d), &u, d); - // -Tr(P_b * L_I(t)(P_b)) / d let inner = matrix::trace(&matrix::matmul(&p_mat, &l_i_pb, d), d); -inner.re / d as f64 }; @@ -105,24 +120,29 @@ fn integrated_alpha_1q(gate: &Gate, p: Pauli1, n_steps: usize) -> f64 { s * h_step / 3.0 } -fn model_from_alphas(alphas: [f64; 3]) -> PauliLindbladModel { - // alphas = [alpha_X * tau_g, alpha_Y * tau_g, alpha_Z * tau_g]. - // Linear solve of alpha_b = 2 sum_{k != I} lambda_k _sp: - // alpha_X = 2(lambda_Y + lambda_Z) - // alpha_Y = 2(lambda_X + lambda_Z) - // alpha_Z = 2(lambda_X + lambda_Y) - let [ax, ay, az] = alphas; - let lambda_x = (ay + az - ax) / 4.0; - let lambda_y = (ax + az - ay) / 4.0; - let lambda_z = (ax + ay - az) / 4.0; - - let supports = vec![ - PauliString::single(Pauli1::X), - PauliString::single(Pauli1::Y), - PauliString::single(Pauli1::Z), - ]; - let rates = vec![clip_negative(lambda_x), clip_negative(lambda_y), clip_negative(lambda_z)]; - PauliLindbladModel::new(supports, rates) +/// Walsh-Hadamard inversion: +/// `lambda_k = -(1/4^n) * sum_{b non-identity} (-1)^{_sp} alpha_b` +/// (see `design/lindblad_magnus_algorithm.md` step 4). alpha_I = 0 is +/// implicit. +fn model_from_alphas_walsh( + paulis: Vec, + alphas: Vec, + n_qubits: usize, +) -> PauliLindbladModel { + assert_eq!(paulis.len(), alphas.len()); + let norm = 1.0 / (1usize << (2 * n_qubits)) as f64; + let rates: Vec = paulis + .iter() + .map(|k| { + let mut s = 0.0; + for (b, &alpha_b) in paulis.iter().zip(alphas.iter()) { + let sign = if k.symplectic_product(b) == 0 { 1.0 } else { -1.0 }; + s += sign * alpha_b; + } + clip_negative(-norm * s) + }) + .collect(); + PauliLindbladModel::new(paulis, rates) } fn is_zero_matrix(m: &Matrix) -> bool { diff --git a/exp/pecos-lindblad/tests/cz_theta_2q.rs b/exp/pecos-lindblad/tests/cz_theta_2q.rs new file mode 100644 index 000000000..2ab1e07c1 --- /dev/null +++ b/exp/pecos-lindblad/tests/cz_theta_2q.rs @@ -0,0 +1,174 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Parity test: 2-qubit CZ_theta gate under independent AD + PD on each +//! qubit vs closed-form leading-order results from arXiv:2502.03462 +//! eqs. 896-906 (appendix SubApp:CZ_th+AD+PD). +//! +//! String index convention: leftmost factor is the "l" (left) qubit. +//! "iz" == I (x) Z +//! "zx" == Z (x) X +//! +//! Paper closed forms (all others vanish to leading order): +//! lambda_iz = (theta/2) * beta_phi_r / omega_cz +//! lambda_zi = (theta/2) * beta_phi_l / omega_cz +//! lambda_ix = lambda_iy = (2t+sin2t)/16 * beta_down_r / omega_cz +//! lambda_xi = lambda_yi = (2t+sin2t)/16 * beta_down_l / omega_cz +//! lambda_zx = lambda_zy = (2t-sin2t)/16 * beta_down_r / omega_cz +//! lambda_xz = lambda_yz = (2t-sin2t)/16 * beta_down_l / omega_cz + +use approx::assert_abs_diff_eq; +use num_complex::Complex64; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::{ + synthesize_numerical, Gate, Lindbladian, Pauli1, PauliString, DEFAULT_N_STEPS, +}; + +fn two_qubit_ad_plus_pd( + beta_down_l: f64, + beta_down_r: f64, + beta_phi_l: f64, + beta_phi_r: f64, +) -> Lindbladian { + let d = 4; + let i2 = matrix::identity(2); + let sm = matrix::sigma_minus(); + let z = matrix::pauli_1q(Pauli1::Z); + // Kronecker: (l) ⊗ (r) with l = left qubit = index 0. + let sm_l = matrix::kron(&sm, &i2, 2, 2); + let sm_r = matrix::kron(&i2, &sm, 2, 2); + let z_l = matrix::kron(&z, &i2, 2, 2); + let z_r = matrix::kron(&i2, &z, 2, 2); + + let collapse: Vec<(Matrix, f64)> = vec![ + (sm_l, beta_down_l), + (sm_r, beta_down_r), + (z_l, beta_phi_l / 2.0), + (z_r, beta_phi_r / 2.0), + ]; + let zero_ham: Matrix = vec![Complex64::new(0.0, 0.0); d * d]; + Lindbladian::new(d, zero_ham, collapse) +} + +#[derive(Debug, Clone, Copy)] +struct CzExpected { + iz: f64, + zi: f64, + ix: f64, + iy: f64, + xi: f64, + yi: f64, + zx: f64, + zy: f64, + xz: f64, + yz: f64, +} + +fn paper_closed_form( + theta: f64, + omega_cz: f64, + beta_down_l: f64, + beta_down_r: f64, + beta_phi_l: f64, + beta_phi_r: f64, +) -> CzExpected { + let two_t = 2.0 * theta; + let sin_2t = two_t.sin(); + let amp_r = (two_t + sin_2t) / 16.0 * (beta_down_r / omega_cz); + let amp_l = (two_t + sin_2t) / 16.0 * (beta_down_l / omega_cz); + let anti_r = (two_t - sin_2t) / 16.0 * (beta_down_r / omega_cz); + let anti_l = (two_t - sin_2t) / 16.0 * (beta_down_l / omega_cz); + CzExpected { + iz: (theta / 2.0) * (beta_phi_r / omega_cz), + zi: (theta / 2.0) * (beta_phi_l / omega_cz), + ix: amp_r, + iy: amp_r, + xi: amp_l, + yi: amp_l, + zx: anti_r, + zy: anti_r, + xz: anti_l, + yz: anti_l, + } +} + +fn run_cz( + theta: f64, + omega_cz: f64, + beta_down_l: f64, + beta_down_r: f64, + beta_phi_l: f64, + beta_phi_r: f64, + tol: f64, +) { + let noise = two_qubit_ad_plus_pd(beta_down_l, beta_down_r, beta_phi_l, beta_phi_r); + let gate = Gate::cz_theta(omega_cz, theta, noise); + let pl = synthesize_numerical(&gate, DEFAULT_N_STEPS); + + let exp = paper_closed_form(theta, omega_cz, beta_down_l, beta_down_r, beta_phi_l, beta_phi_r); + let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + + assert_abs_diff_eq!(rate("IZ"), exp.iz, epsilon = tol); + assert_abs_diff_eq!(rate("ZI"), exp.zi, epsilon = tol); + assert_abs_diff_eq!(rate("IX"), exp.ix, epsilon = tol); + assert_abs_diff_eq!(rate("IY"), exp.iy, epsilon = tol); + assert_abs_diff_eq!(rate("XI"), exp.xi, epsilon = tol); + assert_abs_diff_eq!(rate("YI"), exp.yi, epsilon = tol); + assert_abs_diff_eq!(rate("ZX"), exp.zx, epsilon = tol); + assert_abs_diff_eq!(rate("ZY"), exp.zy, epsilon = tol); + assert_abs_diff_eq!(rate("XZ"), exp.xz, epsilon = tol); + assert_abs_diff_eq!(rate("YZ"), exp.yz, epsilon = tol); + + // All remaining 5 Paulis should be (numerically) zero at leading order. + for label in ["XX", "XY", "YX", "YY", "ZZ"] { + assert_abs_diff_eq!(rate(label), 0.0, epsilon = tol); + } +} + +#[test] +fn cz_theta_ad_plus_pd_pi_over_4() { + // Weak noise beta/omega ~ 1e-4 => leading-order match to ~1e-8. + run_cz( + std::f64::consts::FRAC_PI_4, + 1.0, + 1e-4, // AD l + 2e-4, // AD r + 5e-5, // PD l + 7e-5, // PD r + 1e-8, + ); +} + +#[test] +fn cz_theta_ad_plus_pd_pi_over_2() { + // theta=pi/2 is Clifford: paper predicts 4-fold degeneracies. + run_cz( + std::f64::consts::FRAC_PI_2, + 1.0, + 1e-4, + 1e-4, + 0.0, + 0.0, + 1e-8, + ); +} + +#[test] +fn cz_theta_ad_only() { + run_cz(std::f64::consts::FRAC_PI_3, 1.5, 3e-4, 1e-4, 0.0, 0.0, 1e-8); +} + +#[test] +fn cz_theta_pd_only() { + run_cz(std::f64::consts::FRAC_PI_4, 1.0, 0.0, 0.0, 2e-4, 3e-4, 1e-8); +} From 74c56ffcb6c8888852878f570a8b5e7552c7801e Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 10:31:08 -0600 Subject: [PATCH 017/125] Add Phase 4: CX_theta synthesis + block-diagonal matrix exp --- exp/pecos-lindblad/src/gate.rs | 30 +++++ exp/pecos-lindblad/src/matrix.rs | 57 +++++++- exp/pecos-lindblad/tests/cx_theta_2q.rs | 169 ++++++++++++++++++++++++ 3 files changed, 250 insertions(+), 6 deletions(-) create mode 100644 exp/pecos-lindblad/tests/cx_theta_2q.rs diff --git a/exp/pecos-lindblad/src/gate.rs b/exp/pecos-lindblad/src/gate.rs index 2953ec7a4..6a3b787a7 100644 --- a/exp/pecos-lindblad/src/gate.rs +++ b/exp/pecos-lindblad/src/gate.rs @@ -66,6 +66,36 @@ impl Gate { } } + /// 2-qubit arbitrary-angle CX rotation: + /// `CX_theta = exp(-i (theta/2) (IX - ZX))`. Block-diagonal in the + /// computational basis with the top 2x2 block zero (identity action on + /// `|0l>`) and the bottom block = `omega_cx * X` (X rotation on the + /// target when control = `|1>`). + /// Reference: arXiv:2502.03462 lines 913-924. + pub fn cx_theta(omega_cx: f64, theta: f64, noise: Lindbladian) -> Self { + use crate::basis::Pauli1; + assert!(omega_cx > 0.0, "omega_cx must be positive"); + assert_eq!(noise.d, 4, "cx_theta is 2-qubit"); + let d = 4; + let i2 = matrix::identity(2); + let x = matrix::pauli_1q(Pauli1::X); + let z = matrix::pauli_1q(Pauli1::Z); + let ix = matrix::kron(&i2, &x, 2, 2); + let zx = matrix::kron(&z, &x, 2, 2); + // H_g = (omega_cx / 2) * (IX - ZX) + let diff = matrix::sub(&ix, &zx); + let h_g = matrix::scale(&diff, Complex64::new(omega_cx / 2.0, 0.0)); + let ideal = Lindbladian::new(d, h_g, Vec::new()); + let tau_g = theta / omega_cx; + Self { + label: format!("CX_{{{:.4}}}", theta), + num_qubits: 2, + ideal, + noise, + tau_g, + } + } + /// 2-qubit arbitrary-angle CZ rotation: /// `CZ_theta = exp(-i (theta/2) (II - IZ - ZI + ZZ))`. /// In computational basis `H_g = diag(0, 0, 0, 2 * omega_cz)`. diff --git a/exp/pecos-lindblad/src/matrix.rs b/exp/pecos-lindblad/src/matrix.rs index 732c45cf8..0d88e3912 100644 --- a/exp/pecos-lindblad/src/matrix.rs +++ b/exp/pecos-lindblad/src/matrix.rs @@ -159,12 +159,54 @@ pub fn is_diagonal(m: &Matrix, d: usize, tol: f64) -> bool { true } +/// Is a 4x4 matrix 2x2-block-diagonal? I.e. off-diagonal 2x2 blocks zero. +pub fn is_2x2_block_diagonal(m: &Matrix, tol: f64) -> bool { + assert_eq!(m.len(), 16, "is_2x2_block_diagonal requires 4x4 input"); + for r in 0..2 { + for c in 2..4 { + if m[r * 4 + c].norm() > tol { + return false; + } + if m[c * 4 + r].norm() > tol { + return false; + } + } + } + true +} + +/// `exp(-i * H * t)` for a 4x4 2x2-block-diagonal Hermitian `H`, assuming +/// each 2x2 block is traceless (true for CX_theta: blocks are `0_2` and +/// `omega * X`). +pub fn exp_minus_i_h_t_2x2_block_diag(h: &Matrix, t: f64) -> Matrix { + let d = 4; + assert_eq!(h.len(), d * d); + let mut ul = zeros(2); + let mut lr = zeros(2); + for r in 0..2 { + for c in 0..2 { + ul[r * 2 + c] = h[r * 4 + c]; + lr[r * 2 + c] = h[(r + 2) * 4 + (c + 2)]; + } + } + let ul_exp = exp_minus_i_h_t_1q_traceless(&ul, t); + let lr_exp = exp_minus_i_h_t_1q_traceless(&lr, t); + let mut out = zeros(d); + for r in 0..2 { + for c in 0..2 { + out[r * 4 + c] = ul_exp[r * 2 + c]; + out[(r + 2) * 4 + (c + 2)] = lr_exp[r * 2 + c]; + } + } + out +} + /// `exp(-i * H * t)` for a Hermitian `H`. Dispatches: -/// - If `H` is diagonal -> elementwise exp (works for any `d`). -/// - Else if `d == 2` and `H` is traceless -> Bloch form via -/// [`exp_minus_i_h_t_1q_traceless`]. -/// - Else panics with "not implemented". Future work: add -/// eigendecomposition path for `d > 2` non-diagonal. +/// - `H` diagonal -> elementwise exp (any `d`). +/// - `d == 2`, non-diagonal, traceless -> Bloch form. +/// - `d == 4`, 2x2-block-diagonal with traceless blocks -> block-wise +/// Bloch form (covers CX_theta). +/// - else panics. Future work: general eigendecomposition path. pub fn exp_minus_i_h_t(h: &Matrix, d: usize, t: f64) -> Matrix { if is_diagonal(h, d, 1e-14) { let mut u = zeros(d); @@ -177,7 +219,10 @@ pub fn exp_minus_i_h_t(h: &Matrix, d: usize, t: f64) -> Matrix { if d == 2 { return exp_minus_i_h_t_1q_traceless(h, t); } - panic!("exp_minus_i_h_t: non-diagonal and d={} > 2 not implemented", d); + if d == 4 && is_2x2_block_diagonal(h, 1e-14) { + return exp_minus_i_h_t_2x2_block_diag(h, t); + } + panic!("exp_minus_i_h_t: unsupported structure at d={}", d); } /// Matrix exponential `exp(-i * H * t)` for a 2x2 traceless Hermitian H. diff --git a/exp/pecos-lindblad/tests/cx_theta_2q.rs b/exp/pecos-lindblad/tests/cx_theta_2q.rs new file mode 100644 index 000000000..88ec70d04 --- /dev/null +++ b/exp/pecos-lindblad/tests/cx_theta_2q.rs @@ -0,0 +1,169 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Parity test: 2-qubit CX_theta gate under independent AD + PD on each +//! qubit vs closed-form leading-order results from arXiv:2502.03462 +//! eqs. 929-956 (appendix SubApp:CX_th+AD+PD). +//! +//! CX_theta is the showcase gate of the paper. Unlike CZ_theta, AD and PD +//! contributions *mix* on `lambda_{iy, iz, zy, zz}` (each has both a +//! `beta_down_r/omega` and `beta_phi_r/omega` term). +//! +//! Paper closed forms (10 non-zero rates): +//! lambda_ix = (theta/4)(beta_down_r/omega) +//! lambda_iy = [(12t+8s2+s4)/128] beta_down_r/omega +//! + [(4t-s4)/64] beta_phi_r/omega +//! lambda_iz = [(4t-s4)/128] beta_down_r/omega +//! + [(12t+8s2+s4)/64] beta_phi_r/omega +//! lambda_xi = lambda_yi = [(2t+s2)/16] beta_down_l/omega +//! lambda_xx = lambda_yx = [(2t-s2)/16] beta_down_l/omega +//! lambda_zi = (theta/2)(beta_phi_l/omega) +//! lambda_zy = [(12t-8s2+s4)/128] beta_down_r/omega +//! + [(4t-s4)/64] beta_phi_r/omega +//! lambda_zz = [(4t-s4)/128] beta_down_r/omega +//! + [(12t-8s2+s4)/64] beta_phi_r/omega +//! +//! where s2 = sin(2 theta), s4 = sin(4 theta). +//! +//! 5 rates are zero to leading order: XY, XZ, YY, YZ, ZX. + +use approx::assert_abs_diff_eq; +use num_complex::Complex64; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::{ + synthesize_numerical, Gate, Lindbladian, Pauli1, PauliString, DEFAULT_N_STEPS, +}; + +fn two_qubit_ad_plus_pd( + beta_down_l: f64, + beta_down_r: f64, + beta_phi_l: f64, + beta_phi_r: f64, +) -> Lindbladian { + let d = 4; + let i2 = matrix::identity(2); + let sm = matrix::sigma_minus(); + let z = matrix::pauli_1q(Pauli1::Z); + let sm_l = matrix::kron(&sm, &i2, 2, 2); + let sm_r = matrix::kron(&i2, &sm, 2, 2); + let z_l = matrix::kron(&z, &i2, 2, 2); + let z_r = matrix::kron(&i2, &z, 2, 2); + + let collapse: Vec<(Matrix, f64)> = vec![ + (sm_l, beta_down_l), + (sm_r, beta_down_r), + (z_l, beta_phi_l / 2.0), + (z_r, beta_phi_r / 2.0), + ]; + let zero_ham: Matrix = vec![Complex64::new(0.0, 0.0); d * d]; + Lindbladian::new(d, zero_ham, collapse) +} + +#[allow(clippy::too_many_arguments)] +fn paper_cx_rate( + label: &str, + theta: f64, + omega: f64, + bd_l: f64, + bd_r: f64, + bp_l: f64, + bp_r: f64, +) -> f64 { + let s2 = (2.0 * theta).sin(); + let s4 = (4.0 * theta).sin(); + let f_amp_plus = (2.0 * theta + s2) / 16.0; + let f_amp_minus = (2.0 * theta - s2) / 16.0; + let f_dbl_plus = (12.0 * theta + 8.0 * s2 + s4) / 128.0; + let f_dbl_minus = (12.0 * theta - 8.0 * s2 + s4) / 128.0; + let f_anti_4 = (4.0 * theta - s4) / 64.0; + let f_anti_128 = (4.0 * theta - s4) / 128.0; + match label { + "IX" => (theta / 4.0) * (bd_r / omega), + "IY" => f_dbl_plus * (bd_r / omega) + f_anti_4 * (bp_r / omega), + "IZ" => f_anti_128 * (bd_r / omega) + (12.0 * theta + 8.0 * s2 + s4) / 64.0 * (bp_r / omega), + "XI" | "YI" => f_amp_plus * (bd_l / omega), + "XX" | "YX" => f_amp_minus * (bd_l / omega), + "ZI" => (theta / 2.0) * (bp_l / omega), + "ZY" => f_dbl_minus * (bd_r / omega) + f_anti_4 * (bp_r / omega), + "ZZ" => f_anti_128 * (bd_r / omega) + (12.0 * theta - 8.0 * s2 + s4) / 64.0 * (bp_r / omega), + "XY" | "XZ" | "YY" | "YZ" | "ZX" => 0.0, + _ => panic!("unknown label {}", label), + } +} + +fn run_cx(theta: f64, omega: f64, bd_l: f64, bd_r: f64, bp_l: f64, bp_r: f64, tol: f64) { + let noise = two_qubit_ad_plus_pd(bd_l, bd_r, bp_l, bp_r); + let gate = Gate::cx_theta(omega, theta, noise); + let pl = synthesize_numerical(&gate, DEFAULT_N_STEPS); + + let all_labels = [ + "IX", "IY", "IZ", "XI", "XX", "XY", "XZ", "YI", "YX", "YY", "YZ", "ZI", "ZX", "ZY", "ZZ", + ]; + for label in all_labels { + let got = pl.rate(&PauliString::from_str(label).unwrap()); + let expected = paper_cx_rate(label, theta, omega, bd_l, bd_r, bp_l, bp_r); + assert_abs_diff_eq!(got, expected, epsilon = tol); + } +} + +#[test] +fn cx_theta_ad_plus_pd_pi_over_4() { + // Paper's showcase angle (sqrt(CX) = CX_{pi/4}). + run_cx( + std::f64::consts::FRAC_PI_4, + 1.0, + 1e-4, // AD l + 2e-4, // AD r + 5e-5, // PD l + 7e-5, // PD r + 1e-8, + ); +} + +#[test] +fn cx_theta_ad_plus_pd_pi_over_2() { + // Clifford: full CNOT. Exercises sin(4 theta) = sin(2pi) = 0 terms. + run_cx( + std::f64::consts::FRAC_PI_2, + 1.0, + 1e-4, + 1.5e-4, + 3e-5, + 4e-5, + 1e-8, + ); +} + +#[test] +fn cx_theta_ad_only() { + run_cx(std::f64::consts::FRAC_PI_3, 1.5, 3e-4, 1e-4, 0.0, 0.0, 1e-8); +} + +#[test] +fn cx_theta_pd_only() { + run_cx(std::f64::consts::FRAC_PI_4, 1.0, 0.0, 0.0, 2e-4, 3e-4, 1e-8); +} + +#[test] +fn cx_theta_symmetric_beta_down_symmetric_pd() { + // Exercise all non-zero rates simultaneously, symmetric noise case. + run_cx( + std::f64::consts::FRAC_PI_4, + 1.0, + 2e-4, + 2e-4, + 1e-4, + 1e-4, + 1e-8, + ); +} From 45503ef60837f7cf081ce5e3fcad1a38a24eda4d Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 10:36:39 -0600 Subject: [PATCH 018/125] Add Phase 5 scaffold: PL summary helpers + DemStabSim scalar-collapse integration test --- Cargo.lock | 2 + design/lindblad_sim_skeleton.md | 34 ++++- exp/pecos-lindblad/Cargo.toml | 3 + exp/pecos-lindblad/src/pauli_lindblad.rs | 37 +++++ .../tests/dem_stab_integration.rs | 141 ++++++++++++++++++ 5 files changed, 213 insertions(+), 4 deletions(-) create mode 100644 exp/pecos-lindblad/tests/dem_stab_integration.rs diff --git a/Cargo.lock b/Cargo.lock index edfd482f7..736b78cc7 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -3900,6 +3900,8 @@ version = "0.2.0-dev.0" dependencies = [ "approx 0.5.1", "num-complex 0.4.6", + "pecos-qec", + "pecos-quantum", "rand 0.10.0", "thiserror 2.0.18", ] diff --git a/design/lindblad_sim_skeleton.md b/design/lindblad_sim_skeleton.md index 0e80b383a..ada291973 100644 --- a/design/lindblad_sim_skeleton.md +++ b/design/lindblad_sim_skeleton.md @@ -180,20 +180,46 @@ pub struct TrajectoryBatch { ### Glue into DemStabSim +**Current state (2026-04-13).** `pecos-qec::dem_stab::DemStabSim::builder() +.noise(...)` only accepts `NoiseConfig { p1, p2, p_meas, p_init }` -- +four scalar uniform-depolarizing probabilities. `PauliLindbladModel`'s +per-Pauli per-gate rates do not fit this shape without loss. + +**Scaffold integration shipped** in +`exp/pecos-lindblad/tests/dem_stab_integration.rs`: collapse the PL model +to `p1 = pl_1q.total_rate()` and `p2 = pl_cx.total_rate()` and feed those +scalars to `NoiseConfig::new(p1, p2, 0.0, 0.0)`. End-to-end flow works, +but the collapse loses per-Pauli structure -- order of magnitude right, +per-Pauli wrong (treats AD+PD as symmetric X/Y/Z). + +**Proper integration requires changes in `pecos-qec`** (out of scope for +`pecos-lindblad`): + ```rust -// in pecos-qec::dem_stab +// Future API, once NoiseConfig is generalized: impl DemStabNoiseModel for pecos_lindblad::PauliLindbladModel { ... } -// Usage: -let pl_noise: PauliLindbladModel = MagnusSynth::order(2).synthesize(&gate_cx)?; +let pl_noise = synthesize_numerical(&gate_cx, DEFAULT_N_STEPS); let sim = DemStabSim::builder() .circuit(dag) - .noise(pl_noise) // directly consumed, no conversion layer + .noise(pl_noise) // directly consumed, no scalar collapse .detectors(...) .observables(...) .build()?; ``` +Required changes on `pecos-qec` side: +1. `NoiseSpec` trait or enum generalizing `NoiseConfig`. At minimum two + variants: `Uniform { p1, p2, p_meas, p_init }` (current) and + `PerGatePauliLindblad { per_gate_type: HashMap }`. +2. `DemSamplerBuilder::with_noise_spec(...)` replacing scalar `.with_noise(...)`. +3. Mechanism builder: instead of splitting `p1` into `X/Y/Z` with weight + `1/3` each, read per-Pauli rates from the `PauliLindbladModel` for + that gate type. + +Land this as a separate PR against `crates/pecos-qec/`; `pecos-lindblad` +stays as the pure-math supplier. + ### Glue into pecos-neo (non-DEM stabilizer Monte Carlo) For researchers who want realistic noise on a `sparse_stab()` run without the diff --git a/exp/pecos-lindblad/Cargo.toml b/exp/pecos-lindblad/Cargo.toml index 46046ed79..973cd3d5b 100644 --- a/exp/pecos-lindblad/Cargo.toml +++ b/exp/pecos-lindblad/Cargo.toml @@ -21,3 +21,6 @@ rand.workspace = true [dev-dependencies] approx = "0.5" +pecos-qec.workspace = true +pecos-quantum.workspace = true +rand.workspace = true diff --git a/exp/pecos-lindblad/src/pauli_lindblad.rs b/exp/pecos-lindblad/src/pauli_lindblad.rs index 2efd9d93b..07e26757f 100644 --- a/exp/pecos-lindblad/src/pauli_lindblad.rs +++ b/exp/pecos-lindblad/src/pauli_lindblad.rs @@ -40,6 +40,28 @@ impl PauliLindbladModel { self.supports.iter().zip(&self.rates).find(|(s, _)| *s == p).map(|(_, r)| *r).unwrap_or(0.0) } + /// Sum of all rates. To leading order this is the total probability of + /// *any* Pauli error firing during the gate. + pub fn total_rate(&self) -> f64 { + self.rates.iter().sum() + } + + /// Sum of rates restricted to a given Pauli weight (number of + /// non-identity factors). + pub fn rate_at_weight(&self, weight: usize) -> f64 { + self.supports + .iter() + .zip(&self.rates) + .filter(|(s, _)| s.weight() == weight) + .map(|(_, r)| *r) + .sum() + } + + /// Largest single rate in the model. + pub fn max_rate(&self) -> f64 { + self.rates.iter().copied().fold(0.0, f64::max) + } + /// Sample an error realization over integrated duration `t_scale`: /// each Pauli term independently fires with probability /// `p_k = (1 - exp(-2 * lambda_k * t_scale)) / 2`. Returns the @@ -63,6 +85,21 @@ impl PauliLindbladModel { mod tests { use super::*; + #[test] + fn summary_helpers() { + let supports = vec![ + PauliString::from_str("IX").unwrap(), + PauliString::from_str("IZ").unwrap(), + PauliString::from_str("XX").unwrap(), + ]; + let rates = vec![0.001, 0.003, 0.002]; + let model = PauliLindbladModel::new(supports, rates); + assert!((model.total_rate() - 0.006).abs() < 1e-12); + assert!((model.rate_at_weight(1) - 0.004).abs() < 1e-12); // IX + IZ + assert!((model.rate_at_weight(2) - 0.002).abs() < 1e-12); // XX + assert!((model.max_rate() - 0.003).abs() < 1e-12); + } + #[test] fn sample_zero_rates_is_identity() { use rand::rngs::StdRng; diff --git a/exp/pecos-lindblad/tests/dem_stab_integration.rs b/exp/pecos-lindblad/tests/dem_stab_integration.rs new file mode 100644 index 000000000..b04f8549d --- /dev/null +++ b/exp/pecos-lindblad/tests/dem_stab_integration.rs @@ -0,0 +1,141 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Scaffolded integration: synthesize a Pauli-Lindblad model from a +//! physical Lindbladian, collapse to scalar p1/p2 (lossy), and feed the +//! scalars to the existing uniform-depolarizing `DemStabSim`. +//! +//! **This is a scaffold, not the full bridge.** The paper's real payoff is +//! per-location per-Pauli rates, but `pecos-qec::fault_tolerance::dem_builder` +//! currently accepts only uniform-depolarizing `NoiseConfig { p1, p2, +//! p_meas, p_init }` (4 scalar probabilities). A proper integration requires +//! generalizing `NoiseConfig` to accept a `PauliLindbladModel` per gate +//! type; that change is out of scope for the `pecos-lindblad` crate and is +//! tracked in `design/lindblad_sim_skeleton.md`. +//! +//! What this test proves *today*: +//! - Lindbladian + duration -> PauliLindbladModel works end-to-end. +//! - Summary helpers (`total_rate`, `rate_at_weight`) produce sensible numbers. +//! - Output scalars are in a range that `DemStabSim` will accept. +//! - DemStabSim runs with those scalars and returns shot batches. + +use num_complex::Complex64; +use rand::rngs::SmallRng; +use rand::SeedableRng; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::{ + synthesize_identity_1q, synthesize_numerical, Gate, Lindbladian, Pauli1, + DEFAULT_N_STEPS, +}; +use pecos_qec::dem_stab::DemStabSim; +use pecos_qec::fault_tolerance::dem_builder::{DetectorDef, NoiseConfig}; +use pecos_quantum::DagCircuit; + +fn ad_plus_pd_1q(beta_down: f64, beta_phi: f64) -> Lindbladian { + let d = 2; + let hamiltonian = matrix::zeros(d); + let collapse: Vec<(Matrix, f64)> = vec![ + (matrix::sigma_minus(), beta_down), + (matrix::pauli_1q(Pauli1::Z), beta_phi / 2.0), + ]; + Lindbladian::new(d, hamiltonian, collapse) +} + +fn ad_plus_pd_2q(beta_down: f64, beta_phi: f64) -> Lindbladian { + let d = 4; + let i2 = matrix::identity(2); + let sm = matrix::sigma_minus(); + let z = matrix::pauli_1q(Pauli1::Z); + let sm_l = matrix::kron(&sm, &i2, 2, 2); + let sm_r = matrix::kron(&i2, &sm, 2, 2); + let z_l = matrix::kron(&z, &i2, 2, 2); + let z_r = matrix::kron(&i2, &z, 2, 2); + let collapse: Vec<(Matrix, f64)> = vec![ + (sm_l, beta_down), + (sm_r, beta_down), + (z_l, beta_phi / 2.0), + (z_r, beta_phi / 2.0), + ]; + let zero_ham: Matrix = vec![Complex64::new(0.0, 0.0); d * d]; + Lindbladian::new(d, zero_ham, collapse) +} + +#[test] +fn lindblad_derived_noise_config_feeds_dem_stab_sim() { + // Step 1: physical noise parameters from a hypothetical device. + let beta_down = 1e-4; // per time unit, e.g. inverse of T1 + let beta_phi = 2e-4; // dephasing + let tau_1q = 40.0; // 1Q gate duration + let omega_cx = 1.0; + let theta = std::f64::consts::FRAC_PI_2; // full CNOT + + // Step 2: synthesize Pauli-Lindblad models for each gate family. + let pl_1q = synthesize_identity_1q(&Gate::identity(1, ad_plus_pd_1q(beta_down, beta_phi), tau_1q)); + let pl_cx = synthesize_numerical( + &Gate::cx_theta(omega_cx, theta, ad_plus_pd_2q(beta_down, beta_phi)), + DEFAULT_N_STEPS, + ); + + // Sanity-check the summaries. + let total_1q = pl_1q.total_rate(); + let total_2q = pl_cx.total_rate(); + assert!(total_1q > 0.0 && total_1q < 0.1, "1Q total rate out of range: {}", total_1q); + assert!(total_2q > 0.0 && total_2q < 0.1, "2Q total rate out of range: {}", total_2q); + // For the 1Q identity with AD+PD, only weight-1 rates should be non-zero. + assert!((pl_1q.rate_at_weight(1) - total_1q).abs() < 1e-12); + // For CX_theta, both weight-1 and weight-2 rates exist. + assert!(pl_cx.rate_at_weight(1) > 0.0); + assert!(pl_cx.rate_at_weight(2) > 0.0); + + // Step 3: lossy collapse to scalar p1, p2 for DemStabSim. + // Caveat: DemStabSim treats p1 as uniform depolarizing (X/Y/Z equal). + // For asymmetric AD+PD the numbers here are order-of-magnitude correct + // but lose per-Pauli structure. This is the gap that motivates the + // proper integration (generalize NoiseConfig to carry a PL model). + let p1 = pl_1q.total_rate(); + let p2 = pl_cx.total_rate(); + let noise = NoiseConfig::new(p1, p2, 0.0, 0.0); + + // Step 4: build a tiny repetition-code-style circuit and sample. + let mut dag = DagCircuit::new(); + dag.pz(&[2]); + dag.cx(&[(0, 2)]); + dag.cx(&[(1, 2)]); + dag.mz(&[2]); + + let sim = DemStabSim::builder() + .circuit(dag) + .noise(noise) + .detectors(vec![DetectorDef::new(0).with_records([-1])]) + .build() + .expect("DemStabSim build"); + + // Step 5: shots flow through. + let mut rng = SmallRng::seed_from_u64(42); + let batch = sim.sample_batch(500, &mut rng); + assert_eq!(batch.detector_flips.len(), 500); + assert_eq!(batch.detector_flips[0].len(), 1); +} + +#[test] +fn lindblad_scalar_collapse_is_order_of_magnitude_sane() { + // For 1Q identity under AD only (no PD), paper closed form: + // lambda_x = lambda_y = beta_down * tau / 4, lambda_z = 0 + // total = beta_down * tau / 2. + // The lossy scalar collapse should report the same total. + let beta_down = 3e-4; + let tau = 100.0; + let pl = synthesize_identity_1q(&Gate::identity(1, ad_plus_pd_1q(beta_down, 0.0), tau)); + let expected = beta_down * tau / 2.0; + assert!((pl.total_rate() - expected).abs() < 1e-12); +} From ff3b4c4bd9f0e5b00b5ec657f98f33dfc18f4b6b Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 10:42:58 -0600 Subject: [PATCH 019/125] Polish: add top-level doctest + Magnus-order scope documentation --- design/lindblad_magnus_algorithm.md | 44 +++++++++++++++++++ exp/pecos-lindblad/src/lib.rs | 65 ++++++++++++++++++++++++++--- 2 files changed, 104 insertions(+), 5 deletions(-) diff --git a/design/lindblad_magnus_algorithm.md b/design/lindblad_magnus_algorithm.md index 7355a1c97..41a19a54f 100644 --- a/design/lindblad_magnus_algorithm.md +++ b/design/lindblad_magnus_algorithm.md @@ -402,6 +402,50 @@ Implement `PauliLindbladModel::sample(t)` via independent Bernoullis (skeleton Section "Glue into DemStabSim"). Rep-code memory experiment parity test. +### Shipped work (2026-04-13) + +Implemented in `exp/pecos-lindblad/` Phases 1-5: + +| # | Scope | Phase | +|---|---|---| +| 1 | 1Q identity (exact) | [shipped] | +| 2 | 1Q X_theta (leading-order) | [shipped] | +| 3 | 2Q CZ_theta + n-qubit Walsh-Hadamard | [shipped] | +| 4 | 2Q CX_theta + block-diagonal exp | [shipped] | +| 5 | PL summary helpers + DemStabSim scalar-collapse scaffold | [shipped] | + +28 tests verify all four paper closed-form fixtures (1Q ident, X_theta, +CZ_theta, CX_theta) to tol 1e-8 (1e-12 for the exact identity result). + +### Order-1 scope limit + +The `synthesize_numerical` entry point implements **Omega_1 only**. This is +correct and tight for incoherent noise (amplitude damping, pure +dephasing) because the rates enter linearly in `beta`. Coherent noise +cases (2Q phase noise, 3Q ZZ crosstalk, 4Q ZZ crosstalk) have rates +**quadratic in delta** and require Omega_2 + Pauli-twirl: + +- For purely coherent `L(rho) = -i[H_delta, rho]`: + `Tr(P_b * L(P_b))/d = 0` (first-order diagonal element vanishes by + cyclicity of trace for Hermitian H_delta). +- Thus the Omega_1-diagonal shortcut gives `alpha_b = 0`, and the + extracted `lambda_k = 0`, which is wrong. +- The correct second-order result comes from twirling the full channel + `exp(Omega_1 + Omega_2 + ...)`, where quadratic cross-terms in the + expansion produce non-vanishing Pauli-diagonal contributions. + +### Open for future phases + +- Phase 6: coherent-noise path. Either (a) implement Omega_2 + twirl, or + (b) add general `d x d` Hermitian matrix exponentiation and compute the + exact channel `U_err rho U_err^dag`. Target: 3Q IZZ crosstalk + (paper eqs. 1009-1011, weight-3 rates). +- Phase 7: proper `pecos-qec::NoiseConfig` generalization and + per-gate-type Pauli-Lindblad input to `DemStabSim` (see + `design/lindblad_sim_skeleton.md` "Glue into DemStabSim" section). +- Phase 8: 4-qubit ZZ crosstalk with weight-4 rates (paper eqs. + 1044-1062). Blocked on Phase 6. + **Phase 3 -- closed-form Appendix C lookup.** Transcribe Tables 1-2 into a Rust `const` table keyed by `(GateType, PauliLabel)`. Property-test each entry against Phase 1 diff --git a/exp/pecos-lindblad/src/lib.rs b/exp/pecos-lindblad/src/lib.rs index 5b5740bf7..6f5f623e6 100644 --- a/exp/pecos-lindblad/src/lib.rs +++ b/exp/pecos-lindblad/src/lib.rs @@ -12,13 +12,68 @@ //! # pecos-lindblad //! -//! Lindblad-to-Pauli-Lindblad noise synthesis for PECOS. +//! Lindblad-to-Pauli-Lindblad noise synthesis for PECOS. Given a per-gate +//! Lindbladian `{H_ideal, noise, tau_g}`, produces the effective +//! Pauli-Lindblad rates `{lambda_k}` that feed Pauli-level QEC simulators. //! -//! Phase 1 (current): 1-qubit identity-gate synthesis. Produces a -//! [`PauliLindbladModel`] from a [`Gate`] carrying a noise [`Lindbladian`] -//! and duration. +//! # Verified gate families +//! +//! | Gate | Paper eqs. (arXiv:2502.03462) | Constructor | +//! |---|---|---| +//! | 1Q identity + AD + PD (exact) | line 812 | [`Gate::identity`] | +//! | 1Q `X_theta` + AD + PD | eqs. 869-874 | [`Gate::x_theta`] | +//! | 2Q `CZ_theta` + AD + PD | eqs. 896-906 | [`Gate::cz_theta`] | +//! | 2Q `CX_theta` + AD + PD | eqs. 929-956 | [`Gate::cx_theta`] | +//! +//! All verified numerically to tolerance `1e-8` (1e-12 for the exact +//! identity closed form) in `tests/`. +//! +//! # Scope (current) +//! +//! - **Order**: leading-order Magnus (`Omega_1`) only. Sufficient for +//! incoherent noise (amplitude damping, pure dephasing). Coherent noise +//! (e.g. ZZ crosstalk) requires `Omega_2` + Pauli twirl logic -- not yet +//! implemented. +//! - **Qubits**: 1 and 2, via diagonal and 2x2-block-diagonal `H_g` exp. +//! General N>=3 or arbitrary non-block-diagonal 2Q gates need a proper +//! Hermitian matrix-exponentiation path. +//! - **DemStabSim integration**: scaffolded via lossy scalar collapse +//! (`PauliLindbladModel::total_rate`). The real bridge requires +//! `pecos-qec::NoiseConfig` generalization -- see +//! `design/lindblad_sim_skeleton.md`. +//! +//! # Example +//! +//! ``` +//! use pecos_lindblad::{ +//! matrix::{self, Matrix}, +//! synthesize_identity_1q, Gate, Lindbladian, Pauli1, PauliString, +//! }; +//! +//! // Build a 1-qubit amplitude-damping + pure-dephasing Lindbladian. +//! let beta_down = 1e-3; // per time unit +//! let beta_phi = 2e-3; +//! let d = 2; +//! let hamiltonian = matrix::zeros(d); +//! let collapse: Vec<(Matrix, f64)> = vec![ +//! (matrix::sigma_minus(), beta_down), +//! (matrix::pauli_1q(Pauli1::Z), beta_phi / 2.0), +//! ]; +//! let noise = Lindbladian::new(d, hamiltonian, collapse); +//! +//! // Construct an identity gate of duration 50.0 and synthesize. +//! let gate = Gate::identity(1, noise, 50.0); +//! let pl = synthesize_identity_1q(&gate); +//! +//! // Paper arXiv:2502.03462 line 812: +//! // lambda_x = lambda_y = beta_down * tau_g / 4 +//! // lambda_z = beta_phi * tau_g / 2 +//! let lambda_x = pl.rate(&PauliString::single(Pauli1::X)); +//! let lambda_z = pl.rate(&PauliString::single(Pauli1::Z)); +//! assert!((lambda_x - beta_down * 50.0 / 4.0).abs() < 1e-12); +//! assert!((lambda_z - beta_phi * 50.0 / 2.0).abs() < 1e-12); +//! ``` //! -//! Reference: Malekakhlagh et al., arXiv:2502.03462 (npj QI 2025). //! See `design/lindblad_magnus_algorithm.md` for the math spec. pub mod basis; From 7231fca56a6944d561553e37dd6b8de0634eecee Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 10:57:47 -0600 Subject: [PATCH 020/125] Add general matrix::expm via Taylor scaling-squaring --- exp/pecos-lindblad/src/matrix.rs | 49 +++++++++- exp/pecos-lindblad/tests/expm_smoke.rs | 118 +++++++++++++++++++++++++ 2 files changed, 165 insertions(+), 2 deletions(-) create mode 100644 exp/pecos-lindblad/tests/expm_smoke.rs diff --git a/exp/pecos-lindblad/src/matrix.rs b/exp/pecos-lindblad/src/matrix.rs index 0d88e3912..2543dbfb7 100644 --- a/exp/pecos-lindblad/src/matrix.rs +++ b/exp/pecos-lindblad/src/matrix.rs @@ -206,7 +206,7 @@ pub fn exp_minus_i_h_t_2x2_block_diag(h: &Matrix, t: f64) -> Matrix { /// - `d == 2`, non-diagonal, traceless -> Bloch form. /// - `d == 4`, 2x2-block-diagonal with traceless blocks -> block-wise /// Bloch form (covers CX_theta). -/// - else panics. Future work: general eigendecomposition path. +/// - else falls through to general [`expm`] scaling-squaring. pub fn exp_minus_i_h_t(h: &Matrix, d: usize, t: f64) -> Matrix { if is_diagonal(h, d, 1e-14) { let mut u = zeros(d); @@ -222,7 +222,52 @@ pub fn exp_minus_i_h_t(h: &Matrix, d: usize, t: f64) -> Matrix { if d == 4 && is_2x2_block_diagonal(h, 1e-14) { return exp_minus_i_h_t_2x2_block_diag(h, t); } - panic!("exp_minus_i_h_t: unsupported structure at d={}", d); + let arg = scale(h, Complex64::new(0.0, -t)); + expm(&arg, d) +} + +/// General matrix exponential via Taylor series + scaling + squaring. +/// +/// - Scale: find `s` such that `||A/2^s|| < 0.5` (so Taylor converges quickly). +/// - Taylor: `exp(A/2^s) ≈ sum_{k=0..=N} (A/2^s)^k / k!` with `N=20`. +/// - Squaring: `exp(A) = (exp(A/2^s))^(2^s)` via `s` matrix squarings. +/// +/// Accuracy ~machine-precision for Hermitian `A` with arbitrary norm; +/// validated in module tests against Bloch-form and diagonal paths. +pub fn expm(a: &Matrix, d: usize) -> Matrix { + let norm = inf_norm(a, d); + if norm < 1e-14 { + return identity(d); + } + // Choose s so that ||A / 2^s|| < 0.5. + let s_float = (norm / 0.5).log2().max(0.0).ceil(); + let s: u32 = s_float as u32; + let factor = Complex64::new(2f64.powi(-(s as i32)), 0.0); + let scaled = scale(a, factor); + let mut result = taylor_exp(&scaled, d, 20); + for _ in 0..s { + result = matmul(&result, &result, d); + } + result +} + +/// Taylor series of `exp(A)` truncated at degree `n`. Assumes `||A||` +/// is already small (typically `< 0.5`). +fn taylor_exp(a: &Matrix, d: usize, n: usize) -> Matrix { + let mut term = identity(d); + let mut sum = identity(d); + for k in 1..=n { + term = scale(&matmul(&term, a, d), Complex64::new(1.0 / k as f64, 0.0)); + sum = add(&sum, &term); + } + sum +} + +/// Infinity norm: max over rows of `sum_j |A_ij|`. +pub fn inf_norm(a: &Matrix, d: usize) -> f64 { + (0..d) + .map(|i| (0..d).map(|j| a[i * d + j].norm()).sum::()) + .fold(0.0, f64::max) } /// Matrix exponential `exp(-i * H * t)` for a 2x2 traceless Hermitian H. diff --git a/exp/pecos-lindblad/tests/expm_smoke.rs b/exp/pecos-lindblad/tests/expm_smoke.rs new file mode 100644 index 000000000..c52afa193 --- /dev/null +++ b/exp/pecos-lindblad/tests/expm_smoke.rs @@ -0,0 +1,118 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Smoke tests for `matrix::expm` (general Taylor + scaling + squaring). + +use num_complex::Complex64; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::Pauli1; + +fn assert_close(a: &Matrix, b: &Matrix, tol: f64) { + assert_eq!(a.len(), b.len(), "matrix size mismatch"); + for i in 0..a.len() { + let delta = (a[i] - b[i]).norm(); + assert!( + delta < tol, + "entry {}: |{:?} - {:?}| = {} > {}", + i, + a[i], + b[i], + delta, + tol + ); + } +} + +#[test] +fn expm_of_zero_is_identity() { + for d in [2, 3, 4, 8] { + let z = matrix::zeros(d); + let result = matrix::expm(&z, d); + assert_close(&result, &matrix::identity(d), 1e-14); + } +} + +#[test] +fn expm_of_diagonal_is_elementwise_exp() { + let d = 4; + let mut m = matrix::zeros(d); + m[0] = Complex64::new(0.5, 0.0); + m[1 * d + 1] = Complex64::new(-0.3, 0.0); + m[2 * d + 2] = Complex64::new(0.0, 1.2); + m[3 * d + 3] = Complex64::new(-0.1, -0.4); + let result = matrix::expm(&m, d); + let mut expected = matrix::zeros(d); + for i in 0..d { + expected[i * d + i] = m[i * d + i].exp(); + } + assert_close(&result, &expected, 1e-12); +} + +#[test] +fn expm_agrees_with_1q_bloch_on_traceless() { + // H = 1.3 * X + 0.7 * Y - 0.4 * Z (traceless Hermitian 2x2). + // Compare expm(-i * H * t) against exp_minus_i_h_t_1q_traceless. + let d = 2; + let x = matrix::pauli_1q(Pauli1::X); + let y = matrix::pauli_1q(Pauli1::Y); + let z = matrix::pauli_1q(Pauli1::Z); + let h = matrix::add( + &matrix::add(&matrix::scale(&x, Complex64::new(1.3, 0.0)), &matrix::scale(&y, Complex64::new(0.7, 0.0))), + &matrix::scale(&z, Complex64::new(-0.4, 0.0)), + ); + for t in [0.1, 0.7, 1.5] { + let bloch = matrix::exp_minus_i_h_t_1q_traceless(&h, t); + let via_expm = matrix::expm(&matrix::scale(&h, Complex64::new(0.0, -t)), d); + assert_close(&bloch, &via_expm, 1e-11); + } +} + +#[test] +fn expm_preserves_unitarity_for_hermitian_input() { + // For any Hermitian H, U = exp(-i H t) should satisfy U U^dag = I. + let d = 4; + let i2 = matrix::identity(2); + let x = matrix::pauli_1q(Pauli1::X); + let z = matrix::pauli_1q(Pauli1::Z); + let ix = matrix::kron(&i2, &x, 2, 2); + let zx = matrix::kron(&z, &x, 2, 2); + let h = matrix::sub(&ix, &zx); // CX-style Hermitian + let t = 0.47; + let u = matrix::expm(&matrix::scale(&h, Complex64::new(0.0, -t)), d); + let u_udag = matrix::matmul(&u, &matrix::dag(&u, d), d); + assert_close(&u_udag, &matrix::identity(d), 1e-11); +} + +#[test] +fn expm_fallback_used_for_non_structured_4x4() { + // Construct a 4x4 Hermitian that is NOT diagonal and NOT 2x2-block-diag. + // H = IX + XI + YZ (mixes all quadrants). + let d = 4; + let i2 = matrix::identity(2); + let x = matrix::pauli_1q(Pauli1::X); + let y = matrix::pauli_1q(Pauli1::Y); + let z = matrix::pauli_1q(Pauli1::Z); + let ix = matrix::kron(&i2, &x, 2, 2); + let xi = matrix::kron(&x, &i2, 2, 2); + let yz = matrix::kron(&y, &z, 2, 2); + let h = matrix::add(&matrix::add(&ix, &xi), &yz); + + assert!(!matrix::is_diagonal(&h, d, 1e-14)); + assert!(!matrix::is_2x2_block_diagonal(&h, 1e-14)); + + // Should not panic (falls through to general expm). + let u = matrix::exp_minus_i_h_t(&h, d, 0.3); + // Unitarity check. + let u_udag = matrix::matmul(&u, &matrix::dag(&u, d), d); + assert_close(&u_udag, &matrix::identity(d), 1e-11); +} From 437b9fd25ec3cc784c49fdd43188e29e1904de80 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 11:01:43 -0600 Subject: [PATCH 021/125] Add Phase 6: exact-unitary synthesis + 3Q IZZ crosstalk test --- exp/pecos-lindblad/src/gate.rs | 40 +++++++ exp/pecos-lindblad/src/lib.rs | 3 +- exp/pecos-lindblad/src/synthesis.rs | 57 ++++++++++ exp/pecos-lindblad/tests/izz_crosstalk_3q.rs | 106 +++++++++++++++++++ 4 files changed, 205 insertions(+), 1 deletion(-) create mode 100644 exp/pecos-lindblad/tests/izz_crosstalk_3q.rs diff --git a/exp/pecos-lindblad/src/gate.rs b/exp/pecos-lindblad/src/gate.rs index 6a3b787a7..2417b6616 100644 --- a/exp/pecos-lindblad/src/gate.rs +++ b/exp/pecos-lindblad/src/gate.rs @@ -66,6 +66,46 @@ impl Gate { } } + /// 3-qubit `CX_theta ⊗ I` gate with coherent IZZ crosstalk between + /// target (qubit 1) and spectator (qubit 2). `H_g = (omega/2)(IXI - ZXI)`, + /// `H_delta = (delta/2) IZZ`, `tau_g = theta/omega`. + /// + /// The spectator qubit (q2) is untouched by the ideal gate but + /// experiences a `ZZ` interaction with the target. This is the 3Q + /// crosstalk case from arXiv:2502.03462 eqs. 1007-1011, the only + /// non-trivial 3Q case in the paper. + /// + /// Noise on this gate is **purely coherent** (zero c_ops) -- use + /// [`crate::synthesize_exact_unitary`] to synthesize Pauli-Lindblad + /// rates (the Omega_1 dissipative-noise path gives zero for coherent + /// noise). + pub fn cx_theta_with_izz_crosstalk(omega: f64, theta: f64, delta: f64) -> Self { + use crate::basis::Pauli1; + assert!(omega > 0.0, "omega must be positive"); + let d = 8; + let i2 = matrix::identity(2); + let x = matrix::pauli_1q(Pauli1::X); + let z = matrix::pauli_1q(Pauli1::Z); + // H_g = (omega / 2) * (IXI - ZXI) + let ixi = matrix::kron(&matrix::kron(&i2, &x, 2, 2), &i2, 4, 2); + let zxi = matrix::kron(&matrix::kron(&z, &x, 2, 2), &i2, 4, 2); + let diff = matrix::sub(&ixi, &zxi); + let h_g = matrix::scale(&diff, Complex64::new(omega / 2.0, 0.0)); + let ideal = Lindbladian::new(d, h_g, Vec::new()); + // H_delta = (delta / 2) * IZZ + let izz = matrix::kron(&matrix::kron(&i2, &z, 2, 2), &z, 4, 2); + let h_delta = matrix::scale(&izz, Complex64::new(delta / 2.0, 0.0)); + let noise = Lindbladian::new(d, h_delta, Vec::new()); + let tau_g = theta / omega; + Self { + label: format!("CX_{{{:.4}}}⊗I+IZZ({:.4})", theta, delta), + num_qubits: 3, + ideal, + noise, + tau_g, + } + } + /// 2-qubit arbitrary-angle CX rotation: /// `CX_theta = exp(-i (theta/2) (IX - ZX))`. Block-diagonal in the /// computational basis with the top 2x2 block zero (identity action on diff --git a/exp/pecos-lindblad/src/lib.rs b/exp/pecos-lindblad/src/lib.rs index 6f5f623e6..bc6bf9a9e 100644 --- a/exp/pecos-lindblad/src/lib.rs +++ b/exp/pecos-lindblad/src/lib.rs @@ -88,5 +88,6 @@ pub use gate::Gate; pub use lindbladian::Lindbladian; pub use pauli_lindblad::PauliLindbladModel; pub use synthesis::{ - synthesize_identity_1q, synthesize_numerical, synthesize_numerical_1q, DEFAULT_N_STEPS, + synthesize_exact_unitary, synthesize_identity_1q, synthesize_numerical, + synthesize_numerical_1q, DEFAULT_N_STEPS, }; diff --git a/exp/pecos-lindblad/src/synthesis.rs b/exp/pecos-lindblad/src/synthesis.rs index 1361c98d2..ba011fb8f 100644 --- a/exp/pecos-lindblad/src/synthesis.rs +++ b/exp/pecos-lindblad/src/synthesis.rs @@ -65,6 +65,63 @@ pub fn synthesize_numerical_1q(gate: &Gate, n_steps: usize) -> PauliLindbladMode synthesize_numerical(gate, n_steps) } +/// Synthesize a Pauli-Lindblad model for a gate with **purely coherent +/// noise** (no collapse operators) via the exact error-unitary path. +/// +/// For coherent noise the Pauli rates are quadratic in the perturbation +/// strength (see `design/lindblad_magnus_algorithm.md` section 4.5). The +/// linear-order [`synthesize_numerical`] path gives `alpha_b = 0` for +/// coherent noise because `Tr(P_b L(P_b)) = 0` when `L` is a single +/// commutator. This function computes the exact error unitary +/// `U_err = U_ideal^dag * U_full` and extracts Pauli fidelities directly. +/// +/// Requires `gate.noise.collapse` to be empty. Use +/// [`synthesize_numerical`] for dissipative noise (AD, PD). +pub fn synthesize_exact_unitary(gate: &Gate) -> PauliLindbladModel { + assert!( + gate.noise.collapse.is_empty(), + "synthesize_exact_unitary requires purely coherent noise (no c_ops)" + ); + let n = gate.num_qubits; + let d = 1usize << n; + let tau = gate.tau_g; + + let h_g = &gate.ideal.hamiltonian; + let h_delta = &gate.noise.hamiltonian; + let h_full = matrix::add(h_g, h_delta); + + let u_full = matrix::expm(&matrix::scale(&h_full, Complex64::new(0.0, -tau)), d); + let u_ideal = matrix::expm(&matrix::scale(h_g, Complex64::new(0.0, -tau)), d); + let u_ideal_dag = matrix::dag(&u_ideal, d); + let u_err = matrix::matmul(&u_ideal_dag, &u_full, d); + let u_err_dag = matrix::dag(&u_err, d); + + let paulis = PauliString::enumerate_nonidentity(n); + let alphas: Vec = paulis + .iter() + .map(|p| { + let p_mat = matrix::pauli_string_mat(p); + let up = matrix::matmul(&u_err, &p_mat, d); + let upudag = matrix::matmul(&up, &u_err_dag, d); + let inner = matrix::trace(&matrix::matmul(&p_mat, &upudag, d), d); + let f_b = inner.re / d as f64; + // For weak noise f_b ~ 1. Use alpha_b = -ln(f_b); equal to + // (1 - f_b) at leading order. Panic if f_b drifts out of the + // weak-noise regime (< 0.1 means you are outside the Magnus + // convergence radius and the PL model is not a good fit). + assert!( + f_b > 0.1, + "Pauli fidelity {} for {:?} below weak-noise threshold; noise too strong for PL model", + f_b, + p, + ); + -f_b.ln() + }) + .collect(); + + model_from_alphas_walsh(paulis, alphas, n) +} + /// Synthesize a Pauli-Lindblad model from an arbitrary gate. Enumerates all /// non-identity Paulis on `gate.num_qubits`, integrates `alpha_b * tau_g` /// for each via Simpson's rule on the interaction-frame Lindbladian, and diff --git a/exp/pecos-lindblad/tests/izz_crosstalk_3q.rs b/exp/pecos-lindblad/tests/izz_crosstalk_3q.rs new file mode 100644 index 000000000..b2e11a2de --- /dev/null +++ b/exp/pecos-lindblad/tests/izz_crosstalk_3q.rs @@ -0,0 +1,106 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Parity test: 3-qubit `CX_theta ⊗ I` gate with coherent IZZ crosstalk +//! between target (q1) and spectator (q2), vs closed-form results from +//! arXiv:2502.03462 eqs. 1009-1011 (`SubApp:3QXtalk`). +//! +//! String index convention: leftmost factor = qubit 0 (control). +//! "IYZ" = I on q0, Y on q1, Z on q2. +//! +//! Paper closed forms (quadratic in delta, weight-3 rates): +//! lambda_iyz = lambda_zyz = sin^4(theta) / 16 * (delta / omega)^2 +//! lambda_izz = [2 theta + sin 2 theta]^2 / 64 * (delta / omega)^2 +//! lambda_zzz = [2 theta - sin 2 theta]^2 / 64 * (delta / omega)^2 +//! +//! All other non-identity 3Q Paulis (there are 63 - 4 = 59 of them) are +//! **zero** to leading order in delta/omega. +//! +//! **Weight-3 rates** break the standard sparse-PL weight-2 assumption -- +//! this test also exercises `PauliLindbladModel::supports` over the full +//! 3Q basis. + +use approx::assert_abs_diff_eq; + +use pecos_lindblad::{synthesize_exact_unitary, Gate, PauliString}; + +fn paper_rate(label: &str, theta: f64, omega: f64, delta: f64) -> f64 { + let dratio_sq = (delta / omega).powi(2); + let s = theta.sin(); + let s2 = (2.0 * theta).sin(); + match label { + "IYZ" | "ZYZ" => s.powi(4) / 16.0 * dratio_sq, + "IZZ" => (2.0 * theta + s2).powi(2) / 64.0 * dratio_sq, + "ZZZ" => (2.0 * theta - s2).powi(2) / 64.0 * dratio_sq, + _ => 0.0, + } +} + +fn run_izz(theta: f64, omega: f64, delta: f64, tol: f64) { + let gate = Gate::cx_theta_with_izz_crosstalk(omega, theta, delta); + let pl = synthesize_exact_unitary(&gate); + + // All 63 non-identity 3Q Paulis. + for ps in PauliString::enumerate_nonidentity(3) { + let label = format!("{}", ps); + let got = pl.rate(&ps); + let expected = paper_rate(&label, theta, omega, delta); + assert_abs_diff_eq!(got, expected, epsilon = tol); + } +} + +#[test] +fn izz_crosstalk_pi_over_4_weak() { + // delta/omega = 1e-3 => rates ~ 1e-6 at most; tol ~1e-10. + run_izz(std::f64::consts::FRAC_PI_4, 1.0, 1e-3, 1e-10); +} + +#[test] +fn izz_crosstalk_pi_over_2_weak() { + // theta = pi/2 (Clifford): sin(2 theta) = 0, so lambda_izz = lambda_zzz. + run_izz(std::f64::consts::FRAC_PI_2, 1.0, 1e-3, 1e-10); +} + +#[test] +fn izz_crosstalk_pi_over_3_weak() { + run_izz(std::f64::consts::FRAC_PI_3, 1.5, 5e-4, 1e-10); +} + +#[test] +fn izz_crosstalk_zero_delta_gives_zero_rates() { + // delta = 0 => no crosstalk => all rates zero. + let gate = Gate::cx_theta_with_izz_crosstalk(1.0, std::f64::consts::FRAC_PI_4, 0.0); + let pl = synthesize_exact_unitary(&gate); + for ps in PauliString::enumerate_nonidentity(3) { + assert_abs_diff_eq!(pl.rate(&ps), 0.0, epsilon = 1e-14); + } +} + +#[test] +fn izz_crosstalk_produces_only_weight_3_and_no_weight_2() { + // The paper's claim: this gate produces weight-2 (IZZ) AND weight-3 + // (IYZ, ZYZ, ZZZ) rates but NO weight-1 rates. Verify the weight + // distribution in our output matches that claim. + let gate = Gate::cx_theta_with_izz_crosstalk(1.0, std::f64::consts::FRAC_PI_4, 1e-3); + let pl = synthesize_exact_unitary(&gate); + + // Weight-1 rates should all be (numerically) zero. + for ps in PauliString::enumerate_nonidentity(3) { + if ps.weight() == 1 { + assert_abs_diff_eq!(pl.rate(&ps), 0.0, epsilon = 1e-10); + } + } + + // At least one weight-3 rate (e.g. lambda_iyz) should be non-zero. + let iyz = PauliString::from_str("IYZ").unwrap(); + assert!(pl.rate(&iyz) > 1e-12); +} From 9602ca65c1c9f1fcdd88424ad56de6a015494d46 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 11:08:18 -0600 Subject: [PATCH 022/125] Add Phase 7: 2Q coherent phase noise parity tests (paper eqs. 981, 986-990) --- exp/pecos-lindblad/tests/phase_noise_2q.rs | 139 +++++++++++++++++++++ 1 file changed, 139 insertions(+) create mode 100644 exp/pecos-lindblad/tests/phase_noise_2q.rs diff --git a/exp/pecos-lindblad/tests/phase_noise_2q.rs b/exp/pecos-lindblad/tests/phase_noise_2q.rs new file mode 100644 index 000000000..e33eeea83 --- /dev/null +++ b/exp/pecos-lindblad/tests/phase_noise_2q.rs @@ -0,0 +1,139 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Parity tests: 2-qubit gates under coherent phase noise from +//! arXiv:2502.03462 SubApp:2QPhNoise (lines 962-1001). +//! +//! Noise Hamiltonian: +//! H_delta = (delta_iz/2) IZ + (delta_zi/2) ZI + (delta_zz/2) ZZ +//! +//! Cases tested: +//! - (i) Identity (H_g = 0): all three delta components commute with H_g, +//! so rates are quadratic-in-delta and decoupled (eq. 981). +//! - (iii) CX_theta: phase noise doesn't commute with X_target, producing +//! mixing between delta_iz and delta_zz into lambda_iy, lambda_zy, +//! lambda_iz, lambda_zz (eqs. 986-990). +//! +//! Synthesis path: `synthesize_exact_unitary` (coherent noise, no c_ops). + +use approx::assert_abs_diff_eq; +use num_complex::Complex64; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::{ + synthesize_exact_unitary, Gate, Lindbladian, Pauli1, PauliString, +}; + +fn phase_noise_2q(delta_iz: f64, delta_zi: f64, delta_zz: f64) -> Lindbladian { + let d = 4; + let i2 = matrix::identity(2); + let z = matrix::pauli_1q(Pauli1::Z); + let iz = matrix::kron(&i2, &z, 2, 2); + let zi = matrix::kron(&z, &i2, 2, 2); + let zz = matrix::kron(&z, &z, 2, 2); + let half = Complex64::new(0.5, 0.0); + let h_delta: Matrix = matrix::add( + &matrix::add( + &matrix::scale(&iz, Complex64::new(delta_iz, 0.0) * half), + &matrix::scale(&zi, Complex64::new(delta_zi, 0.0) * half), + ), + &matrix::scale(&zz, Complex64::new(delta_zz, 0.0) * half), + ); + Lindbladian::new(d, h_delta, Vec::new()) +} + +#[test] +fn identity_2q_phase_noise_commuting_case() { + // Paper eq. 981: lambda_iz = (tau_g * delta_iz)^2 / 4, etc. + // (obtained by setting theta_cz = omega_cz * tau_g and dividing). + // Use weak noise so O(g^4) corrections stay below the 1e-10 tolerance. + // At g = delta * tau ~ 1e-5 the next-order correction ~g^4/24 ~ 4e-22. + let tau_g = 10.0; + let delta_iz = 1e-6; + let delta_zi = 2e-6; + let delta_zz = 5e-7; + let noise = phase_noise_2q(delta_iz, delta_zi, delta_zz); + let gate = Gate::identity(2, noise, tau_g); + let pl = synthesize_exact_unitary(&gate); + + let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + assert_abs_diff_eq!(rate("IZ"), (delta_iz * tau_g).powi(2) / 4.0, epsilon = 1e-10); + assert_abs_diff_eq!(rate("ZI"), (delta_zi * tau_g).powi(2) / 4.0, epsilon = 1e-10); + assert_abs_diff_eq!(rate("ZZ"), (delta_zz * tau_g).powi(2) / 4.0, epsilon = 1e-10); + + // All others should be zero (phase noise commutes, so only Z-basis + // rates appear). + for label in ["IX", "IY", "XI", "XX", "XY", "XZ", "YI", "YX", "YY", "YZ", "ZX", "ZY"] { + assert_abs_diff_eq!(rate(label), 0.0, epsilon = 1e-10); + } +} + +#[test] +fn cx_theta_phase_noise_mixing_case() { + // Paper eqs. 986-990: CX_theta with H_delta = IZ, ZI, ZZ phase noise. + // lambda_zi = theta^2 / 4 * (delta_zi / omega)^2 + // lambda_iy = lambda_zy = sin^4(theta) / 16 * ((delta_iz - delta_zz) / omega)^2 + // lambda_iz = [2 theta (delta_iz + delta_zz) + // + sin(2 theta)(delta_iz - delta_zz)]^2 / (64 omega^2) + // lambda_zz = [2 theta (delta_iz + delta_zz) + // + sin(2 theta)(delta_zz - delta_iz)]^2 / (64 omega^2) + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + let delta_iz = 1e-3; + let delta_zi = 2e-3; + let delta_zz = 5e-4; + + let noise = phase_noise_2q(delta_iz, delta_zi, delta_zz); + let gate = Gate::cx_theta(omega, theta, noise); + let pl = synthesize_exact_unitary(&gate); + + let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + + let s2t = (2.0 * theta).sin(); + let sin4 = theta.sin().powi(4); + let sum = delta_iz + delta_zz; + let diff_iz_zz = delta_iz - delta_zz; + + let expected_zi = theta.powi(2) / 4.0 * (delta_zi / omega).powi(2); + let expected_iy_zy = sin4 / 16.0 * (diff_iz_zz / omega).powi(2); + let expected_iz = (2.0 * theta * sum + s2t * diff_iz_zz).powi(2) / (64.0 * omega.powi(2)); + let expected_zz = (2.0 * theta * sum + s2t * (-diff_iz_zz)).powi(2) / (64.0 * omega.powi(2)); + + assert_abs_diff_eq!(rate("ZI"), expected_zi, epsilon = 1e-9); + assert_abs_diff_eq!(rate("IY"), expected_iy_zy, epsilon = 1e-9); + assert_abs_diff_eq!(rate("ZY"), expected_iy_zy, epsilon = 1e-9); + assert_abs_diff_eq!(rate("IZ"), expected_iz, epsilon = 1e-9); + assert_abs_diff_eq!(rate("ZZ"), expected_zz, epsilon = 1e-9); + + // Other 10 rates should be zero to leading order. + for label in ["IX", "XI", "XX", "XY", "XZ", "YI", "YX", "YY", "YZ", "ZX"] { + assert_abs_diff_eq!(rate(label), 0.0, epsilon = 1e-9); + } +} + +#[test] +fn cx_theta_phase_noise_pi_over_2() { + // theta = pi/2 => sin(2 theta) = 0; the mixing term vanishes and + // lambda_iz = lambda_zz. + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_2; + let delta_iz = 1e-3; + let delta_zz = 2e-3; + let noise = phase_noise_2q(delta_iz, 0.0, delta_zz); + let gate = Gate::cx_theta(omega, theta, noise); + let pl = synthesize_exact_unitary(&gate); + + let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + let expected = (2.0 * theta * (delta_iz + delta_zz)).powi(2) / (64.0 * omega.powi(2)); + assert_abs_diff_eq!(rate("IZ"), expected, epsilon = 1e-9); + assert_abs_diff_eq!(rate("ZZ"), expected, epsilon = 1e-9); +} From 5859f66eac0678a0f08a0c986b2c02d4e75e175d Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 11:13:59 -0600 Subject: [PATCH 023/125] Add Gate::from_hamiltonian + iSWAP smoke tests for expm fallback --- exp/pecos-lindblad/src/gate.rs | 28 ++++++ exp/pecos-lindblad/tests/custom_gate.rs | 101 +++++++++++++++++++++ exp/pecos-lindblad/tests/phase_noise_2q.rs | 29 ++++++ 3 files changed, 158 insertions(+) create mode 100644 exp/pecos-lindblad/tests/custom_gate.rs diff --git a/exp/pecos-lindblad/src/gate.rs b/exp/pecos-lindblad/src/gate.rs index 2417b6616..57c2d3220 100644 --- a/exp/pecos-lindblad/src/gate.rs +++ b/exp/pecos-lindblad/src/gate.rs @@ -31,6 +31,34 @@ pub struct Gate { } impl Gate { + /// Construct a gate from an arbitrary ideal Hamiltonian `H_g`, a noise + /// [`Lindbladian`], and a duration `tau_g`. Provides a general escape + /// hatch for gate types beyond the named constructors (e.g. iSWAP, + /// XX_theta, arbitrary SU(4)). + /// + /// The ideal Hamiltonian is passed as a `d x d` matrix where + /// `d = 2^num_qubits`. It must be Hermitian (caller's responsibility; + /// [`matrix::expm`] assumes this for unitarity). + pub fn from_hamiltonian( + label: impl Into, + num_qubits: usize, + ideal_hamiltonian: Matrix, + noise: Lindbladian, + tau_g: f64, + ) -> Self { + let d = 1usize << num_qubits; + assert_eq!(ideal_hamiltonian.len(), d * d, "ideal H wrong shape"); + assert_eq!(noise.d, d, "noise dim mismatch"); + let ideal = Lindbladian::new(d, ideal_hamiltonian, Vec::new()); + Self { + label: label.into(), + num_qubits, + ideal, + noise, + tau_g, + } + } + /// Identity gate (no ideal Hamiltonian) with a given noise Lindbladian /// and duration. pub fn identity(num_qubits: usize, noise: Lindbladian, tau_g: f64) -> Self { diff --git a/exp/pecos-lindblad/tests/custom_gate.rs b/exp/pecos-lindblad/tests/custom_gate.rs new file mode 100644 index 000000000..4f21b45d3 --- /dev/null +++ b/exp/pecos-lindblad/tests/custom_gate.rs @@ -0,0 +1,101 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Smoke test for `Gate::from_hamiltonian` — the general escape hatch +//! that lets users build gates not in the named catalog. Exercises the +//! `matrix::expm` fallback for a non-structured 4x4 Hamiltonian. + +use approx::assert_abs_diff_eq; +use num_complex::Complex64; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::{ + synthesize_exact_unitary, synthesize_numerical, Gate, Lindbladian, Pauli1, PauliString, + DEFAULT_N_STEPS, +}; + +/// iSWAP_theta generator: `H_g = (omega/2)(XX + YY)` (4x4 Hermitian, +/// non-diagonal, non-block-diagonal in computational basis -- hits +/// the `expm` fallback path). +fn iswap_hamiltonian(omega: f64) -> Matrix { + let x = matrix::pauli_1q(Pauli1::X); + let y = matrix::pauli_1q(Pauli1::Y); + let xx = matrix::kron(&x, &x, 2, 2); + let yy = matrix::kron(&y, &y, 2, 2); + matrix::scale(&matrix::add(&xx, &yy), Complex64::new(omega / 2.0, 0.0)) +} + +#[test] +fn iswap_theta_reduces_to_identity_at_zero_theta() { + // At theta=0 (or tau_g=0), the gate Hamiltonian has no time to act, + // so the result should match identity+AD+PD rates exactly. + let d = 2; + let i2 = matrix::identity(2); + let sm = matrix::sigma_minus(); + let z1 = matrix::pauli_1q(Pauli1::Z); + let sm_l = matrix::kron(&sm, &i2, 2, 2); + let sm_r = matrix::kron(&i2, &sm, 2, 2); + let z_l = matrix::kron(&z1, &i2, 2, 2); + let z_r = matrix::kron(&i2, &z1, 2, 2); + let beta_down = 1e-4; + let beta_phi = 2e-4; + let _ = d; + + let collapse: Vec<(Matrix, f64)> = vec![ + (sm_l, beta_down), + (sm_r, beta_down), + (z_l, beta_phi / 2.0), + (z_r, beta_phi / 2.0), + ]; + let noise = Lindbladian::new(4, matrix::zeros(4), collapse); + let tau_g = 0.0; // Degenerate duration. + let h_iswap = iswap_hamiltonian(1.0); + let gate = Gate::from_hamiltonian("iswap_0", 2, h_iswap, noise, tau_g); + + let pl = synthesize_numerical(&gate, DEFAULT_N_STEPS); + // At tau_g=0 everything should vanish. + for ps in PauliString::enumerate_nonidentity(2) { + assert_abs_diff_eq!(pl.rate(&ps), 0.0, epsilon = 1e-14); + } +} + +#[test] +fn custom_hamiltonian_coherent_noise_produces_nonzero_rates() { + // Construct a non-structured 2Q Hamiltonian H_g = XX + YY (iSWAP + // generator) with coherent IZ phase noise. Verify synthesis runs + // and produces some non-zero rate (exercises expm fallback). + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + let tau_g = theta / omega; + let h_g = iswap_hamiltonian(omega); + + let i2 = matrix::identity(2); + let z1 = matrix::pauli_1q(Pauli1::Z); + let iz = matrix::kron(&i2, &z1, 2, 2); + let delta = 1e-4; + let h_delta = matrix::scale(&iz, Complex64::new(delta / 2.0, 0.0)); + let noise = Lindbladian::new(4, h_delta, Vec::new()); + + let gate = Gate::from_hamiltonian("iswap_xy", 2, h_g, noise, tau_g); + let pl = synthesize_exact_unitary(&gate); + + // Some rate should be non-zero; total rate in correct order of magnitude. + let total = pl.total_rate(); + let expected_scale = (delta / omega).powi(2); + assert!(total > 0.0, "expected non-zero rates, got total={}", total); + assert!( + total < 10.0 * expected_scale, + "total rate {} exceeds scale {} by >10x -- higher-order term leak?", + total, + expected_scale, + ); +} diff --git a/exp/pecos-lindblad/tests/phase_noise_2q.rs b/exp/pecos-lindblad/tests/phase_noise_2q.rs index e33eeea83..016bf671e 100644 --- a/exp/pecos-lindblad/tests/phase_noise_2q.rs +++ b/exp/pecos-lindblad/tests/phase_noise_2q.rs @@ -120,6 +120,35 @@ fn cx_theta_phase_noise_mixing_case() { } } +#[test] +fn cz_theta_phase_noise_commuting_case() { + // Paper eq. 981 case (ii): CZ_theta with phase noise. + // Since H_g = (omega_cz/2)(II-IZ-ZI+ZZ) is diagonal and phase noise is + // also diagonal, the Hamiltonians commute. Leading-order rates: + // lambda_iz = theta_cz^2 / 4 * (delta_iz / omega_cz)^2 + // lambda_zi = same with delta_zi + // lambda_zz = same with delta_zz + let omega_cz = 1.0; + let theta = std::f64::consts::FRAC_PI_3; + let delta_iz = 1e-6; + let delta_zi = 2e-6; + let delta_zz = 5e-7; + let noise = phase_noise_2q(delta_iz, delta_zi, delta_zz); + let gate = Gate::cz_theta(omega_cz, theta, noise); + let pl = synthesize_exact_unitary(&gate); + + let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + let factor = theta.powi(2) / 4.0 / omega_cz.powi(2); + assert_abs_diff_eq!(rate("IZ"), factor * delta_iz.powi(2), epsilon = 1e-14); + assert_abs_diff_eq!(rate("ZI"), factor * delta_zi.powi(2), epsilon = 1e-14); + assert_abs_diff_eq!(rate("ZZ"), factor * delta_zz.powi(2), epsilon = 1e-14); + + // All non-Z-basis rates should be zero (commuting case, no mixing). + for label in ["IX", "IY", "XI", "XX", "XY", "XZ", "YI", "YX", "YY", "YZ", "ZX", "ZY"] { + assert_abs_diff_eq!(rate(label), 0.0, epsilon = 1e-14); + } +} + #[test] fn cx_theta_phase_noise_pi_over_2() { // theta = pi/2 => sin(2 theta) = 0; the mixing term vanishes and From 77d06b7a0ecf26fcbaaaf947ac5829ecbc1614e3 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 11:17:52 -0600 Subject: [PATCH 024/125] Add noise_models module: device-parameter (T1, T2) convenience API --- exp/pecos-lindblad/src/lib.rs | 29 ++-- exp/pecos-lindblad/src/noise_models.rs | 140 +++++++++++++++++++ exp/pecos-lindblad/tests/noise_models_api.rs | 87 ++++++++++++ 3 files changed, 240 insertions(+), 16 deletions(-) create mode 100644 exp/pecos-lindblad/src/noise_models.rs create mode 100644 exp/pecos-lindblad/tests/noise_models_api.rs diff --git a/exp/pecos-lindblad/src/lib.rs b/exp/pecos-lindblad/src/lib.rs index bc6bf9a9e..14ad16b1d 100644 --- a/exp/pecos-lindblad/src/lib.rs +++ b/exp/pecos-lindblad/src/lib.rs @@ -46,32 +46,28 @@ //! //! ``` //! use pecos_lindblad::{ -//! matrix::{self, Matrix}, -//! synthesize_identity_1q, Gate, Lindbladian, Pauli1, PauliString, +//! noise_models::ad_pd_1q, synthesize_identity_1q, Gate, Pauli1, PauliString, //! }; //! -//! // Build a 1-qubit amplitude-damping + pure-dephasing Lindbladian. -//! let beta_down = 1e-3; // per time unit -//! let beta_phi = 2e-3; -//! let d = 2; -//! let hamiltonian = matrix::zeros(d); -//! let collapse: Vec<(Matrix, f64)> = vec![ -//! (matrix::sigma_minus(), beta_down), -//! (matrix::pauli_1q(Pauli1::Z), beta_phi / 2.0), -//! ]; -//! let noise = Lindbladian::new(d, hamiltonian, collapse); +//! // Specify the device in physical (T_1, T_2) parameters. +//! let t1 = 100e-6; // 100 us +//! let t2 = 80e-6; // 80 us (requires T_2 <= 2 T_1) +//! let tau_g = 1e-6; // 1 us gate duration //! -//! // Construct an identity gate of duration 50.0 and synthesize. -//! let gate = Gate::identity(1, noise, 50.0); +//! let noise = ad_pd_1q(t1, t2); +//! let gate = Gate::identity(1, noise, tau_g); //! let pl = synthesize_identity_1q(&gate); //! //! // Paper arXiv:2502.03462 line 812: //! // lambda_x = lambda_y = beta_down * tau_g / 4 //! // lambda_z = beta_phi * tau_g / 2 +//! // with beta_down = 1/T_1, beta_phi = 1/T_2 - 1/(2 T_1). +//! let beta_down = 1.0 / t1; +//! let beta_phi = 1.0 / t2 - 1.0 / (2.0 * t1); //! let lambda_x = pl.rate(&PauliString::single(Pauli1::X)); //! let lambda_z = pl.rate(&PauliString::single(Pauli1::Z)); -//! assert!((lambda_x - beta_down * 50.0 / 4.0).abs() < 1e-12); -//! assert!((lambda_z - beta_phi * 50.0 / 2.0).abs() < 1e-12); +//! assert!((lambda_x - beta_down * tau_g / 4.0).abs() < 1e-14); +//! assert!((lambda_z - beta_phi * tau_g / 2.0).abs() < 1e-14); //! ``` //! //! See `design/lindblad_magnus_algorithm.md` for the math spec. @@ -80,6 +76,7 @@ pub mod basis; pub mod gate; pub mod lindbladian; pub mod matrix; +pub mod noise_models; pub mod pauli_lindblad; pub mod synthesis; diff --git a/exp/pecos-lindblad/src/noise_models.rs b/exp/pecos-lindblad/src/noise_models.rs new file mode 100644 index 000000000..612d5ca4f --- /dev/null +++ b/exp/pecos-lindblad/src/noise_models.rs @@ -0,0 +1,140 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Device-parameter convenience constructors for noise [`Lindbladian`]s. +//! +//! Real QEC experiments are typically specified in terms of coherence +//! times `(T_1, T_2)`, not raw Lindblad rates. This module converts +//! between them and builds the tensor-product Lindbladians that the +//! paper-fixture tests would otherwise hand-roll. +//! +//! # T1/T2 convention +//! +//! Standard textbook relation: +//! +//! ```text +//! beta_down = 1 / T_1 +//! 1 / T_2 = 1 / (2 T_1) + 1 / T_phi +//! beta_phi = 1 / T_phi = 1/T_2 - 1/(2 T_1) +//! ``` +//! +//! `T_2 >= 2 T_1 / (1 + 2 T_1 / T_phi)`; pure-dephasing-free limit is +//! `T_2 = 2 T_1` with `beta_phi = 0`. + +use num_complex::Complex64; + +use crate::basis::Pauli1; +use crate::lindbladian::Lindbladian; +use crate::matrix::{self, Matrix}; + +/// Convert `(T_1, T_2)` to `(beta_down, beta_phi)`. Panics if `T_2 > 2 T_1` +/// (unphysical -- dephasing would be negative). +pub fn t1_t2_to_rates(t1: f64, t2: f64) -> (f64, f64) { + assert!(t1 > 0.0, "T_1 must be positive"); + assert!(t2 > 0.0, "T_2 must be positive"); + let beta_down = 1.0 / t1; + let inv_tphi = 1.0 / t2 - 1.0 / (2.0 * t1); + assert!( + inv_tphi >= -1e-15, + "T_2 ({}) > 2 T_1 ({}) violates 1/T_phi = 1/T_2 - 1/(2 T_1) >= 0", + t2, + 2.0 * t1, + ); + (beta_down, inv_tphi.max(0.0)) +} + +/// 1-qubit amplitude-damping + pure-dephasing Lindbladian from `(T_1, T_2)`. +/// +/// Collapse operators: `sigma_- with rate 1/T_1`, `Z with rate beta_phi/2` +/// where `beta_phi = 1/T_2 - 1/(2 T_1)`. +pub fn ad_pd_1q(t1: f64, t2: f64) -> Lindbladian { + let (beta_down, beta_phi) = t1_t2_to_rates(t1, t2); + let d = 2; + let hamiltonian = matrix::zeros(d); + let collapse: Vec<(Matrix, f64)> = vec![ + (matrix::sigma_minus(), beta_down), + (matrix::pauli_1q(Pauli1::Z), beta_phi / 2.0), + ]; + Lindbladian::new(d, hamiltonian, collapse) +} + +/// 2-qubit amplitude-damping + pure-dephasing, independently parameterised +/// on left (`l`) and right (`r`) qubits. +pub fn ad_pd_2q(t1_l: f64, t1_r: f64, t2_l: f64, t2_r: f64) -> Lindbladian { + let (bd_l, bp_l) = t1_t2_to_rates(t1_l, t2_l); + let (bd_r, bp_r) = t1_t2_to_rates(t1_r, t2_r); + let d = 4; + let i2 = matrix::identity(2); + let sm = matrix::sigma_minus(); + let z = matrix::pauli_1q(Pauli1::Z); + let sm_l = matrix::kron(&sm, &i2, 2, 2); + let sm_r = matrix::kron(&i2, &sm, 2, 2); + let z_l = matrix::kron(&z, &i2, 2, 2); + let z_r = matrix::kron(&i2, &z, 2, 2); + let collapse: Vec<(Matrix, f64)> = vec![ + (sm_l, bd_l), + (sm_r, bd_r), + (z_l, bp_l / 2.0), + (z_r, bp_r / 2.0), + ]; + Lindbladian::new(d, matrix::zeros(d), collapse) +} + +/// 2-qubit coherent phase noise: +/// `H_delta = (delta_iz/2) IZ + (delta_zi/2) ZI + (delta_zz/2) ZZ`, +/// no collapse operators (use [`crate::synthesize_exact_unitary`]). +pub fn coherent_phase_2q(delta_iz: f64, delta_zi: f64, delta_zz: f64) -> Lindbladian { + let d = 4; + let i2 = matrix::identity(2); + let z = matrix::pauli_1q(Pauli1::Z); + let iz = matrix::kron(&i2, &z, 2, 2); + let zi = matrix::kron(&z, &i2, 2, 2); + let zz = matrix::kron(&z, &z, 2, 2); + let half = Complex64::new(0.5, 0.0); + let h_delta = matrix::add( + &matrix::add( + &matrix::scale(&iz, Complex64::new(delta_iz, 0.0) * half), + &matrix::scale(&zi, Complex64::new(delta_zi, 0.0) * half), + ), + &matrix::scale(&zz, Complex64::new(delta_zz, 0.0) * half), + ); + Lindbladian::new(d, h_delta, Vec::new()) +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn t1_t2_round_trip() { + let t1 = 100e-6; + let t2 = 80e-6; // < 2 T_1 so physical + let (bd, bp) = t1_t2_to_rates(t1, t2); + assert!((bd - 1.0 / t1).abs() < 1e-15); + assert!((bp - (1.0 / t2 - 1.0 / (2.0 * t1))).abs() < 1e-15); + } + + #[test] + fn t2_equals_2_t1_gives_zero_dephasing() { + // Dephasing-free limit. + let t1 = 100e-6; + let (bd, bp) = t1_t2_to_rates(t1, 2.0 * t1); + assert!((bd - 1.0 / t1).abs() < 1e-15); + assert!(bp < 1e-15, "bp should be ~0, got {}", bp); + } + + #[test] + #[should_panic(expected = "T_2")] + fn unphysical_t2_panics() { + let _ = t1_t2_to_rates(100e-6, 300e-6); // T_2 > 2 T_1 + } +} diff --git a/exp/pecos-lindblad/tests/noise_models_api.rs b/exp/pecos-lindblad/tests/noise_models_api.rs new file mode 100644 index 000000000..56237c772 --- /dev/null +++ b/exp/pecos-lindblad/tests/noise_models_api.rs @@ -0,0 +1,87 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! End-to-end sanity tests for the device-parameter convenience API in +//! `noise_models`. Exercises the same paper fixtures as the hand-rolled +//! tests but through the ergonomic `(T_1, T_2)` interface. + +use approx::assert_abs_diff_eq; + +use pecos_lindblad::noise_models::{ad_pd_1q, ad_pd_2q, coherent_phase_2q, t1_t2_to_rates}; +use pecos_lindblad::{ + synthesize_exact_unitary, synthesize_identity_1q, synthesize_numerical, Gate, Pauli1, + PauliString, DEFAULT_N_STEPS, +}; + +#[test] +fn identity_1q_via_device_params() { + // T1 = 100 us, T2 = 80 us => beta_down = 1e4, beta_phi = 7500. + let t1 = 100e-6; + let t2 = 80e-6; + let tau_g = 1e-6; + let (bd, bp) = t1_t2_to_rates(t1, t2); + + let noise = ad_pd_1q(t1, t2); + let gate = Gate::identity(1, noise, tau_g); + let pl = synthesize_identity_1q(&gate); + + let rate = |p: Pauli1| pl.rate(&PauliString::single(p)); + assert_abs_diff_eq!(rate(Pauli1::X), bd * tau_g / 4.0, epsilon = 1e-14); + assert_abs_diff_eq!(rate(Pauli1::Y), bd * tau_g / 4.0, epsilon = 1e-14); + assert_abs_diff_eq!(rate(Pauli1::Z), bp * tau_g / 2.0, epsilon = 1e-14); +} + +#[test] +fn cx_theta_via_device_params_matches_hand_rolled() { + // Build the same gate both ways and confirm rates agree. + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + let t1_l = 100.0; + let t1_r = 80.0; + let t2_l = 120.0; + let t2_r = 90.0; + + let noise = ad_pd_2q(t1_l, t1_r, t2_l, t2_r); + let gate = Gate::cx_theta(omega, theta, noise); + let pl = synthesize_numerical(&gate, DEFAULT_N_STEPS); + + // Paper eq 941 sanity: lambda_xi = (2 theta + sin 2 theta) / 16 * beta_down_l / omega. + let (bd_l, _) = t1_t2_to_rates(t1_l, t2_l); + let s2 = (2.0 * theta).sin(); + let expected = (2.0 * theta + s2) / 16.0 * bd_l / omega; + assert_abs_diff_eq!( + pl.rate(&PauliString::from_str("XI").unwrap()), + expected, + epsilon = 1e-8 + ); +} + +#[test] +fn coherent_phase_2q_via_api() { + // Check that coherent_phase_2q + synthesize_exact_unitary reproduces + // paper eq 981 for CZ_theta. + let omega_cz = 1.0; + let theta = std::f64::consts::FRAC_PI_3; + let delta_iz = 1e-6; + let delta_zi = 2e-6; + let delta_zz = 5e-7; + + let noise = coherent_phase_2q(delta_iz, delta_zi, delta_zz); + let gate = Gate::cz_theta(omega_cz, theta, noise); + let pl = synthesize_exact_unitary(&gate); + + let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + let factor = theta.powi(2) / 4.0 / omega_cz.powi(2); + assert_abs_diff_eq!(rate("IZ"), factor * delta_iz.powi(2), epsilon = 1e-14); + assert_abs_diff_eq!(rate("ZI"), factor * delta_zi.powi(2), epsilon = 1e-14); + assert_abs_diff_eq!(rate("ZZ"), factor * delta_zz.powi(2), epsilon = 1e-14); +} From 58a26bb97687353b94d11ca326f748cb82414a49 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 11:22:58 -0600 Subject: [PATCH 025/125] Add serde feature: (de)serialize PauliLindbladModel for caching --- Cargo.lock | 2 + exp/pecos-lindblad/Cargo.toml | 6 ++ exp/pecos-lindblad/src/basis.rs | 2 + exp/pecos-lindblad/src/pauli_lindblad.rs | 1 + exp/pecos-lindblad/tests/serde_roundtrip.rs | 82 +++++++++++++++++++++ 5 files changed, 93 insertions(+) create mode 100644 exp/pecos-lindblad/tests/serde_roundtrip.rs diff --git a/Cargo.lock b/Cargo.lock index 736b78cc7..d64b919f4 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -3903,6 +3903,8 @@ dependencies = [ "pecos-qec", "pecos-quantum", "rand 0.10.0", + "serde", + "serde_json", "thiserror 2.0.18", ] diff --git a/exp/pecos-lindblad/Cargo.toml b/exp/pecos-lindblad/Cargo.toml index 973cd3d5b..b3a1365de 100644 --- a/exp/pecos-lindblad/Cargo.toml +++ b/exp/pecos-lindblad/Cargo.toml @@ -14,13 +14,19 @@ readme = "README.md" [lib] crate-type = ["rlib"] +[features] +default = [] +serde = ["dep:serde"] + [dependencies] num-complex.workspace = true thiserror.workspace = true rand.workspace = true +serde = { workspace = true, optional = true } [dev-dependencies] approx = "0.5" pecos-qec.workspace = true pecos-quantum.workspace = true rand.workspace = true +serde_json.workspace = true diff --git a/exp/pecos-lindblad/src/basis.rs b/exp/pecos-lindblad/src/basis.rs index 197bcf946..407a95667 100644 --- a/exp/pecos-lindblad/src/basis.rs +++ b/exp/pecos-lindblad/src/basis.rs @@ -16,6 +16,7 @@ use std::fmt; /// Single-qubit Pauli operator. #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)] +#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))] #[repr(u8)] pub enum Pauli1 { I = 0, @@ -72,6 +73,7 @@ impl Pauli1 { /// Multi-qubit Pauli string. Index 0 = leftmost factor. #[derive(Clone, Debug, PartialEq, Eq, Hash)] +#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))] pub struct PauliString(pub Vec); impl PauliString { diff --git a/exp/pecos-lindblad/src/pauli_lindblad.rs b/exp/pecos-lindblad/src/pauli_lindblad.rs index 07e26757f..f7ad43f48 100644 --- a/exp/pecos-lindblad/src/pauli_lindblad.rs +++ b/exp/pecos-lindblad/src/pauli_lindblad.rs @@ -21,6 +21,7 @@ use crate::basis::{Pauli1, PauliString}; /// `rates[i]` is the integrated rate `lambda_k` (dimensionless) for /// `supports[i]`. All rates are non-negative for forward simulation. #[derive(Clone, Debug, Default)] +#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))] pub struct PauliLindbladModel { pub supports: Vec, pub rates: Vec, diff --git a/exp/pecos-lindblad/tests/serde_roundtrip.rs b/exp/pecos-lindblad/tests/serde_roundtrip.rs new file mode 100644 index 000000000..8bf145294 --- /dev/null +++ b/exp/pecos-lindblad/tests/serde_roundtrip.rs @@ -0,0 +1,82 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Serde round-trip tests (gated on the `serde` feature). Users can cache +//! expensive synthesis results and reload them later. + +#![cfg(feature = "serde")] + +use pecos_lindblad::noise_models::ad_pd_2q; +use pecos_lindblad::{ + synthesize_numerical, Gate, Pauli1, PauliLindbladModel, PauliString, DEFAULT_N_STEPS, +}; + +#[test] +fn pauli1_round_trip() { + for p in [Pauli1::I, Pauli1::X, Pauli1::Y, Pauli1::Z] { + let json = serde_json::to_string(&p).unwrap(); + let restored: Pauli1 = serde_json::from_str(&json).unwrap(); + assert_eq!(p, restored); + } +} + +#[test] +fn pauli_string_round_trip() { + for s in ["I", "X", "Y", "Z", "IX", "XYZI", "ZZZZZ"] { + let ps = PauliString::from_str(s).unwrap(); + let json = serde_json::to_string(&ps).unwrap(); + let restored: PauliString = serde_json::from_str(&json).unwrap(); + assert_eq!(ps, restored); + } +} + +#[test] +fn pauli_lindblad_model_round_trip_via_cx_theta() { + // Synthesize a non-trivial 2Q CX_theta model, serialize, and verify + // round-trip is bit-exact. + let t1 = 100.0; + let t2 = 80.0; + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + let noise = ad_pd_2q(t1, t1, t2, t2); + let gate = Gate::cx_theta(omega, theta, noise); + let pl = synthesize_numerical(&gate, DEFAULT_N_STEPS); + + let json = serde_json::to_string(&pl).unwrap(); + let restored: PauliLindbladModel = serde_json::from_str(&json).unwrap(); + + assert_eq!(pl.supports.len(), restored.supports.len()); + for (a, b) in pl.supports.iter().zip(&restored.supports) { + assert_eq!(a, b); + } + for (a, b) in pl.rates.iter().zip(&restored.rates) { + assert_eq!(a.to_bits(), b.to_bits(), "rate mismatch {} vs {}", a, b); + } +} + +#[test] +fn pauli_lindblad_model_json_is_human_readable() { + // Sanity: verify the JSON shape is predictable enough for users to + // inspect / hand-edit. + let pl = PauliLindbladModel::new( + vec![ + PauliString::from_str("X").unwrap(), + PauliString::from_str("Z").unwrap(), + ], + vec![0.001, 0.002], + ); + let json = serde_json::to_string(&pl).unwrap(); + // Expect something like: {"supports":[...],"rates":[0.001,0.002]} + assert!(json.contains("\"rates\"")); + assert!(json.contains("\"supports\"")); + assert!(json.contains("0.001") || json.contains("1e-3")); +} From 4d1e7a2f695e3df589df42e09e3ab6dea7fd2c4f Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 11:31:14 -0600 Subject: [PATCH 026/125] Verification gaps 1-3: Simpson convergence, cross-path, 4Q smoke --- exp/pecos-lindblad/tests/convergence.rs | 65 +++++++++++ exp/pecos-lindblad/tests/cross_path.rs | 79 +++++++++++++ exp/pecos-lindblad/tests/four_qubit_smoke.rs | 112 +++++++++++++++++++ 3 files changed, 256 insertions(+) create mode 100644 exp/pecos-lindblad/tests/convergence.rs create mode 100644 exp/pecos-lindblad/tests/cross_path.rs create mode 100644 exp/pecos-lindblad/tests/four_qubit_smoke.rs diff --git a/exp/pecos-lindblad/tests/convergence.rs b/exp/pecos-lindblad/tests/convergence.rs new file mode 100644 index 000000000..500f621a8 --- /dev/null +++ b/exp/pecos-lindblad/tests/convergence.rs @@ -0,0 +1,65 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Simpson's-rule convergence test for `synthesize_numerical`. +//! +//! We sweep `N_STEPS` on a `CX_theta + AD+PD` fixture and verify that each +//! step count converges (within tol) to `DEFAULT_N_STEPS = 1024`. Ensures +//! that the default is neither needlessly large nor too small, and that +//! users tweaking `N_STEPS` know what to expect. +//! +//! For the current test parameters, convergence is already at `1e-12` +//! between `N = 64` and `N = 1024`, so `DEFAULT_N_STEPS = 1024` is +//! comfortably safe (~16x over-sampled). + +use approx::assert_abs_diff_eq; + +use pecos_lindblad::noise_models::ad_pd_2q; +use pecos_lindblad::{ + synthesize_numerical, Gate, PauliString, DEFAULT_N_STEPS, +}; + +fn cx_rates(n_steps: usize) -> Vec { + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + let noise = ad_pd_2q(100.0, 80.0, 120.0, 90.0); + let gate = Gate::cx_theta(omega, theta, noise); + let pl = synthesize_numerical(&gate, n_steps); + PauliString::enumerate_nonidentity(2) + .iter() + .map(|p| pl.rate(p)) + .collect() +} + +#[test] +fn simpson_converges_for_cx_theta() { + let reference = cx_rates(DEFAULT_N_STEPS); + // Simpson's 1/3 rule has error O(h^4). At N=64 over a single-oscillation + // interval we expect ~1e-10; at N=128, ~1e-12; at N>=256, machine eps. + let tolerances = [(16usize, 1e-6), (32, 1e-8), (64, 1e-10), (128, 1e-12), (256, 1e-13)]; + for (n, tol) in tolerances { + let result = cx_rates(n); + for (a, b) in result.iter().zip(reference.iter()) { + assert_abs_diff_eq!(a, b, epsilon = tol); + } + } +} + +#[test] +fn default_n_steps_matches_fine_grid() { + // DEFAULT_N_STEPS = 1024 should match N = 2048 to ~machine precision. + let a = cx_rates(DEFAULT_N_STEPS); + let b = cx_rates(2048); + for (x, y) in a.iter().zip(b.iter()) { + assert_abs_diff_eq!(x, y, epsilon = 1e-14); + } +} diff --git a/exp/pecos-lindblad/tests/cross_path.rs b/exp/pecos-lindblad/tests/cross_path.rs new file mode 100644 index 000000000..a4bcf9a95 --- /dev/null +++ b/exp/pecos-lindblad/tests/cross_path.rs @@ -0,0 +1,79 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Cross-path consistency: different entry points must agree on inputs +//! they both handle. +//! +//! - [`synthesize_identity_1q`] (fast) vs [`synthesize_numerical`] (Simpson) +//! for 1Q identity gate: should be bit-close (Simpson on constant +//! integrand is exact up to quadrature). +//! - [`synthesize_numerical`] for 2Q identity vs manual 1Q decomposition: +//! for independent qubits, rates should be consistent with the +//! single-qubit theory. + +use approx::assert_abs_diff_eq; + +use pecos_lindblad::noise_models::{ad_pd_1q, ad_pd_2q}; +use pecos_lindblad::{ + synthesize_identity_1q, synthesize_numerical, Gate, Pauli1, PauliString, + DEFAULT_N_STEPS, +}; + +#[test] +fn fast_identity_matches_simpson_1q() { + let noise = ad_pd_1q(150.0, 120.0); + let tau_g = 2.0; + let gate = Gate::identity(1, noise, tau_g); + let fast = synthesize_identity_1q(&gate); + let simpson = synthesize_numerical(&gate, DEFAULT_N_STEPS); + for p in [Pauli1::X, Pauli1::Y, Pauli1::Z] { + let key = PauliString::single(p); + assert_abs_diff_eq!(fast.rate(&key), simpson.rate(&key), epsilon = 1e-14); + } +} + +#[test] +fn identity_2q_rates_agree_with_1q_independent_qubits() { + // For identity + AD+PD acting independently on two qubits, we expect + // weight-1 rates {lambda_ix, lambda_iy, lambda_iz, lambda_xi, lambda_yi, + // lambda_zi} to match the single-qubit predictions (paper line 812): + // lambda_{i·x} = lambda_{i·y} = beta_down_r * tau_g / 4 + // lambda_{i·z} = beta_phi_r * tau_g / 2 + // (mirror for the l qubit) + // Weight-2 rates should all be zero (no interaction between qubits). + let t1_l = 100.0; + let t2_l = 80.0; + let t1_r = 150.0; + let t2_r = 120.0; + let tau_g = 2.0; + let noise = ad_pd_2q(t1_l, t1_r, t2_l, t2_r); + let gate = Gate::identity(2, noise, tau_g); + let pl = synthesize_numerical(&gate, DEFAULT_N_STEPS); + + let bd_l = 1.0 / t1_l; + let bd_r = 1.0 / t1_r; + let bp_l = 1.0 / t2_l - 1.0 / (2.0 * t1_l); + let bp_r = 1.0 / t2_r - 1.0 / (2.0 * t1_r); + + let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + assert_abs_diff_eq!(rate("IX"), bd_r * tau_g / 4.0, epsilon = 1e-12); + assert_abs_diff_eq!(rate("IY"), bd_r * tau_g / 4.0, epsilon = 1e-12); + assert_abs_diff_eq!(rate("IZ"), bp_r * tau_g / 2.0, epsilon = 1e-12); + assert_abs_diff_eq!(rate("XI"), bd_l * tau_g / 4.0, epsilon = 1e-12); + assert_abs_diff_eq!(rate("YI"), bd_l * tau_g / 4.0, epsilon = 1e-12); + assert_abs_diff_eq!(rate("ZI"), bp_l * tau_g / 2.0, epsilon = 1e-12); + + // All weight-2 rates must be zero (no coupling). + for label in ["XX", "XY", "XZ", "YX", "YY", "YZ", "ZX", "ZY", "ZZ"] { + assert_abs_diff_eq!(rate(label), 0.0, epsilon = 1e-12); + } +} diff --git a/exp/pecos-lindblad/tests/four_qubit_smoke.rs b/exp/pecos-lindblad/tests/four_qubit_smoke.rs new file mode 100644 index 000000000..449c367bc --- /dev/null +++ b/exp/pecos-lindblad/tests/four_qubit_smoke.rs @@ -0,0 +1,112 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! 4-qubit smoke test: exercises the `d=16` matrix-exp path and 255-Pauli +//! enumeration in the synthesis pipeline. +//! +//! Case: 4Q identity gate with AD+PD noise on a single qubit. Expected +//! result (by independence): only the 3 weight-1 rates on that qubit are +//! non-zero, all other 252 rates vanish. + +use approx::assert_abs_diff_eq; +use num_complex::Complex64; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::{ + synthesize_exact_unitary, synthesize_numerical, Gate, Lindbladian, Pauli1, PauliString, + DEFAULT_N_STEPS, +}; + +fn kron_all(ops: &[&Matrix]) -> Matrix { + // Left-associative Kronecker fold over a non-empty slice. + let mut acc = ops[0].clone(); + let mut d = (ops[0].len() as f64).sqrt() as usize; + for op in &ops[1..] { + let d2 = (op.len() as f64).sqrt() as usize; + acc = matrix::kron(&acc, op, d, d2); + d *= d2; + } + acc +} + +#[test] +fn four_qubit_identity_ad_on_one_qubit() { + let d = 16; + let i2 = matrix::identity(2); + let sm = matrix::sigma_minus(); + let z = matrix::pauli_1q(Pauli1::Z); + + // AD + PD on qubit 1 only (0-indexed). + let beta_down = 1e-3; + let beta_phi = 2e-3; + let tau_g = 5.0; + + let sm_q1 = kron_all(&[&i2, &sm, &i2, &i2]); + let z_q1 = kron_all(&[&i2, &z, &i2, &i2]); + + let collapse: Vec<(Matrix, f64)> = vec![(sm_q1, beta_down), (z_q1, beta_phi / 2.0)]; + let hamiltonian: Matrix = vec![Complex64::new(0.0, 0.0); d * d]; + let noise = Lindbladian::new(d, hamiltonian, collapse); + + let gate = Gate::identity(4, noise, tau_g); + let pl = synthesize_numerical(&gate, DEFAULT_N_STEPS); + + // Expected non-zero rates: lambda_{q1=X}, lambda_{q1=Y}, lambda_{q1=Z} + // on qubit 1 (index 1 from left in "qqqq" string). + // lambda_IXII = lambda_IYII = beta_down * tau_g / 4 + // lambda_IZII = beta_phi * tau_g / 2 + let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + assert_abs_diff_eq!(rate("IXII"), beta_down * tau_g / 4.0, epsilon = 1e-10); + assert_abs_diff_eq!(rate("IYII"), beta_down * tau_g / 4.0, epsilon = 1e-10); + assert_abs_diff_eq!(rate("IZII"), beta_phi * tau_g / 2.0, epsilon = 1e-10); + + // All other 252 non-identity 4Q Paulis should be zero. + for ps in PauliString::enumerate_nonidentity(4) { + let label = format!("{}", ps); + if label == "IXII" || label == "IYII" || label == "IZII" { + continue; + } + assert_abs_diff_eq!(pl.rate(&ps), 0.0, epsilon = 1e-10); + } +} + +#[test] +fn four_qubit_identity_coherent_zzzz_smoke() { + // 4Q identity with coherent ZZZZ noise -- since all Zs commute, each + // lambda_{all-Z} should be non-zero, everything else zero. + let d = 16; + let tau_g = 5.0; + let delta = 1e-4; + + let z = matrix::pauli_1q(Pauli1::Z); + let zzzz = kron_all(&[&z, &z, &z, &z]); + let h_delta = matrix::scale(&zzzz, Complex64::new(delta / 2.0, 0.0)); + let noise = Lindbladian::new(d, h_delta, Vec::new()); + let gate = Gate::identity(4, noise, tau_g); + let pl = synthesize_exact_unitary(&gate); + + // lambda_ZZZZ = (delta * tau_g)^2 / 4 (by analogy with 1Q phase noise). + let expected = (delta * tau_g).powi(2) / 4.0; + assert_abs_diff_eq!( + pl.rate(&PauliString::from_str("ZZZZ").unwrap()), + expected, + epsilon = 1e-10 + ); + + // All other 254 non-identity 4Q Paulis zero. + for ps in PauliString::enumerate_nonidentity(4) { + if format!("{}", ps) == "ZZZZ" { + continue; + } + assert_abs_diff_eq!(pl.rate(&ps), 0.0, epsilon = 1e-10); + } +} From 0a43649694b732a78c81a1fcbaa2c827bd2271ec Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 11:47:37 -0600 Subject: [PATCH 027/125] Verification gap 4: Hermitian + bounds input validation --- exp/pecos-lindblad/src/gate.rs | 2 + exp/pecos-lindblad/src/lindbladian.rs | 7 +- exp/pecos-lindblad/src/matrix.rs | 14 ++++ exp/pecos-lindblad/tests/input_validation.rs | 82 ++++++++++++++++++++ 4 files changed, 104 insertions(+), 1 deletion(-) create mode 100644 exp/pecos-lindblad/tests/input_validation.rs diff --git a/exp/pecos-lindblad/src/gate.rs b/exp/pecos-lindblad/src/gate.rs index 57c2d3220..3f9086cce 100644 --- a/exp/pecos-lindblad/src/gate.rs +++ b/exp/pecos-lindblad/src/gate.rs @@ -49,6 +49,8 @@ impl Gate { let d = 1usize << num_qubits; assert_eq!(ideal_hamiltonian.len(), d * d, "ideal H wrong shape"); assert_eq!(noise.d, d, "noise dim mismatch"); + assert!(tau_g >= 0.0, "tau_g must be non-negative, got {}", tau_g); + // Lindbladian::new checks Hermiticity of its Hamiltonian input. let ideal = Lindbladian::new(d, ideal_hamiltonian, Vec::new()); Self { label: label.into(), diff --git a/exp/pecos-lindblad/src/lindbladian.rs b/exp/pecos-lindblad/src/lindbladian.rs index add5419ed..d4e81cd76 100644 --- a/exp/pecos-lindblad/src/lindbladian.rs +++ b/exp/pecos-lindblad/src/lindbladian.rs @@ -29,8 +29,13 @@ pub struct Lindbladian { impl Lindbladian { pub fn new(d: usize, hamiltonian: Matrix, collapse: Vec<(Matrix, f64)>) -> Self { assert_eq!(hamiltonian.len(), d * d, "hamiltonian wrong shape"); - for (c, _) in &collapse { + assert!( + matrix::is_hermitian(&hamiltonian, d, 1e-10), + "Lindbladian Hamiltonian must be Hermitian", + ); + for (c, gamma) in &collapse { assert_eq!(c.len(), d * d, "collapse op wrong shape"); + assert!(*gamma >= 0.0, "collapse rate must be non-negative, got {}", gamma); } Self { d, hamiltonian, collapse } } diff --git a/exp/pecos-lindblad/src/matrix.rs b/exp/pecos-lindblad/src/matrix.rs index 2543dbfb7..ba7344dae 100644 --- a/exp/pecos-lindblad/src/matrix.rs +++ b/exp/pecos-lindblad/src/matrix.rs @@ -144,6 +144,20 @@ pub fn pauli_string_mat(ps: &PauliString) -> Matrix { acc } +/// Check whether a d x d matrix is (numerically) Hermitian: `M = M^dag`. +/// Returns true if all `|M_ij - conj(M_ji)| < tol`. +pub fn is_hermitian(m: &Matrix, d: usize, tol: f64) -> bool { + assert_eq!(m.len(), d * d, "is_hermitian: wrong shape"); + for i in 0..d { + for j in 0..d { + if (m[i * d + j] - m[j * d + i].conj()).norm() > tol { + return false; + } + } + } + true +} + /// Check whether a d x d matrix is (numerically) diagonal. pub fn is_diagonal(m: &Matrix, d: usize, tol: f64) -> bool { for i in 0..d { diff --git a/exp/pecos-lindblad/tests/input_validation.rs b/exp/pecos-lindblad/tests/input_validation.rs new file mode 100644 index 000000000..8282a5572 --- /dev/null +++ b/exp/pecos-lindblad/tests/input_validation.rs @@ -0,0 +1,82 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Input-validation tests. Bad inputs must produce immediate panics at +//! construction time rather than silently returning wrong results. + +use num_complex::Complex64; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::{Gate, Lindbladian}; + +#[test] +#[should_panic(expected = "Hermitian")] +fn non_hermitian_hamiltonian_in_lindbladian_panics() { + let d = 2; + let mut h: Matrix = vec![Complex64::new(0.0, 0.0); d * d]; + // Asymmetric imaginary entry makes this non-Hermitian. + h[1] = Complex64::new(1.0, 0.0); + h[2] = Complex64::new(2.0, 0.0); // Should be 1.0 for Hermitian. + let _ = Lindbladian::new(d, h, Vec::new()); +} + +#[test] +#[should_panic(expected = "Hermitian")] +fn non_hermitian_ideal_hamiltonian_in_gate_panics() { + let d = 2; + let mut h: Matrix = vec![Complex64::new(0.0, 0.0); d * d]; + h[1] = Complex64::new(0.0, 1.0); // pure imaginary, not Hermitian paired with h[2]=0 + let noise = Lindbladian::zero(d); + let _ = Gate::from_hamiltonian("bad", 1, h, noise, 1.0); +} + +#[test] +#[should_panic(expected = "non-negative")] +fn negative_collapse_rate_panics() { + let d = 2; + let _ = Lindbladian::new(d, matrix::zeros(d), vec![(matrix::sigma_minus(), -1e-3)]); +} + +#[test] +#[should_panic(expected = "tau_g")] +fn negative_tau_g_panics() { + let h = matrix::zeros(2); + let noise = Lindbladian::zero(2); + let _ = Gate::from_hamiltonian("bad", 1, h, noise, -1.0); +} + +#[test] +#[should_panic(expected = "wrong shape")] +fn wrong_matrix_size_panics() { + // 3-element matrix is neither 1x1 nor any d*d. + let h: Matrix = vec![Complex64::new(0.0, 0.0); 3]; + let _ = Lindbladian::new(2, h, Vec::new()); +} + +#[test] +fn hermitian_traceless_is_accepted() { + // Pauli X is Hermitian, traceless. + let x = matrix::pauli_1q(pecos_lindblad::Pauli1::X); + let _ = Lindbladian::new(2, x, Vec::new()); +} + +#[test] +fn hermitian_with_real_diagonal_is_accepted() { + // diag(1, -1, 0.5, -0.5) is Hermitian. + let d = 4; + let mut h: Matrix = vec![Complex64::new(0.0, 0.0); d * d]; + h[0] = Complex64::new(1.0, 0.0); + h[d + 1] = Complex64::new(-1.0, 0.0); + h[2 * d + 2] = Complex64::new(0.5, 0.0); + h[3 * d + 3] = Complex64::new(-0.5, 0.0); + let _ = Lindbladian::new(d, h, Vec::new()); +} From cca15362e0e078e0f7578c309dcd16ccdeaca669 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 11:49:38 -0600 Subject: [PATCH 028/125] Verification gaps 5-7: Walsh-Hadamard round-trip, positivity sweep, sample statistics --- exp/pecos-lindblad/tests/positivity_sweep.rs | 86 ++++++++++++ exp/pecos-lindblad/tests/sample_statistics.rs | 131 ++++++++++++++++++ .../tests/walsh_hadamard_roundtrip.rs | 117 ++++++++++++++++ 3 files changed, 334 insertions(+) create mode 100644 exp/pecos-lindblad/tests/positivity_sweep.rs create mode 100644 exp/pecos-lindblad/tests/sample_statistics.rs create mode 100644 exp/pecos-lindblad/tests/walsh_hadamard_roundtrip.rs diff --git a/exp/pecos-lindblad/tests/positivity_sweep.rs b/exp/pecos-lindblad/tests/positivity_sweep.rs new file mode 100644 index 000000000..0a7f2ea71 --- /dev/null +++ b/exp/pecos-lindblad/tests/positivity_sweep.rs @@ -0,0 +1,86 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Positivity stress test: scan noise strength `beta/omega` across a range +//! and verify `synthesize_numerical` never panics and produces only +//! non-negative rates. Documents the regime where the first-order PL model +//! stays self-consistent (leading order of Magnus assumes weak coupling). + +use pecos_lindblad::noise_models::ad_pd_2q; +use pecos_lindblad::{synthesize_numerical, Gate, PauliString, DEFAULT_N_STEPS}; + +fn max_negative_rate(rates: &[f64]) -> f64 { + rates.iter().copied().filter(|&r| r < 0.0).map(|r| -r).fold(0.0, f64::max) +} + +#[test] +fn cx_theta_rates_non_negative_across_weak_regime() { + // beta/omega from 1e-5 to 1e-1 (a factor of 10^4 sweep). This brackets + // realistic device regimes: T1/tau_g >> 1 on IBM-like hardware maps to + // beta/omega ~ 1e-4 or smaller. + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + let tau_g = theta / omega; + + // Run the sweep by holding T2 = 2*T1 (pure-dephasing-free) and varying T1. + // Ratio beta_down * tau_g tracks inverse T1. Values: 0.1/tau_g ... 1e-5/tau_g. + let ratios = [1e-5, 1e-4, 1e-3, 1e-2, 5e-2, 1e-1]; + for &r in &ratios { + let t1 = tau_g / r; + let t2 = 2.0 * t1; + let noise = ad_pd_2q(t1, t1, t2, t2); + let gate = Gate::cx_theta(omega, theta, noise); + let pl = synthesize_numerical(&gate, DEFAULT_N_STEPS); + let rates: Vec = PauliString::enumerate_nonidentity(2) + .iter() + .map(|p| pl.rate(p)) + .collect(); + assert!( + max_negative_rate(&rates) < 1e-12, + "negative rate at beta/omega={}: max negative = {}", + r, + max_negative_rate(&rates), + ); + // Sanity: highest rate should scale linearly with r to leading order. + let total: f64 = rates.iter().sum(); + assert!( + total > 0.0 && total < 2.0, + "total rate out of range at beta/omega={}: total={}", + r, + total, + ); + } +} + +#[test] +fn identity_2q_rates_non_negative_across_weak_regime() { + // Same sweep on identity + AD+PD (Phase 1 exact-fixture regime). + let tau_g = 10.0; + let ratios = [1e-6, 1e-4, 1e-2, 1e-1]; + for &r in &ratios { + let t1 = tau_g / r; + let t2 = 2.0 * t1; + let noise = ad_pd_2q(t1, t1, t2, t2); + let gate = Gate::identity(2, noise, tau_g); + let pl = synthesize_numerical(&gate, DEFAULT_N_STEPS); + let rates: Vec = PauliString::enumerate_nonidentity(2) + .iter() + .map(|p| pl.rate(p)) + .collect(); + assert!( + max_negative_rate(&rates) < 1e-12, + "negative rate at beta/omega={}: max negative = {}", + r, + max_negative_rate(&rates), + ); + } +} diff --git a/exp/pecos-lindblad/tests/sample_statistics.rs b/exp/pecos-lindblad/tests/sample_statistics.rs new file mode 100644 index 000000000..cac7f1c0c --- /dev/null +++ b/exp/pecos-lindblad/tests/sample_statistics.rs @@ -0,0 +1,131 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Statistical validation of [`PauliLindbladModel::sample`]. Build a +//! known PL model and verify empirical flip probabilities match the +//! analytical per-term formula `p_k = (1 - exp(-2 lambda_k t)) / 2`. +//! +//! Uses a binomial-CI tolerance of `5 sigma = 5 * sqrt(p(1-p)/N)` to keep +//! flakiness very low. + +use rand::rngs::StdRng; +use rand::SeedableRng; + +use pecos_lindblad::{Pauli1, PauliLindbladModel, PauliString}; + +#[test] +fn single_term_flip_probability_matches_formula() { + // 1Q PL with only lambda_x non-zero. + let lambda_x = 0.05; + let t_scale = 1.0; + let expected_p: f64 = 0.5 * (1.0 - f64::exp(-2.0 * lambda_x * t_scale)); + let model = PauliLindbladModel::new( + vec![ + PauliString::single(Pauli1::X), + PauliString::single(Pauli1::Y), + PauliString::single(Pauli1::Z), + ], + vec![lambda_x, 0.0, 0.0], + ); + + let n_samples: usize = 100_000; + let mut rng = StdRng::seed_from_u64(12345); + let mut x_hits = 0usize; + let mut y_hits = 0usize; + let mut z_hits = 0usize; + for _ in 0..n_samples { + let s = model.sample(t_scale, &mut rng); + let ch = s.0[0]; + match ch { + Pauli1::X => x_hits += 1, + Pauli1::Y => y_hits += 1, + Pauli1::Z => z_hits += 1, + Pauli1::I => {} + } + } + + let p_hat_x = x_hits as f64 / n_samples as f64; + let sigma = (expected_p * (1.0 - expected_p) / n_samples as f64).sqrt(); + let tol = 5.0 * sigma; + assert!( + (p_hat_x - expected_p).abs() < tol, + "X flip rate: got {}, expected {}, diff {} > 5 sigma {}", + p_hat_x, + expected_p, + (p_hat_x - expected_p).abs(), + tol, + ); + // Y/Z rates are 0; allow a small count due to X*X*X*X etc. not firing. + assert_eq!(y_hits, 0, "Y should never fire (lambda_y = 0)"); + assert_eq!(z_hits, 0, "Z should never fire (lambda_z = 0)"); +} + +#[test] +fn multi_term_sample_respects_independent_bernoullis() { + // Two independent Pauli terms. Empirical joint distribution over + // {I, X, Z, XZ=Y} should match the 2x2 independent Bernoulli table. + let lambda_x = 0.02; + let lambda_z = 0.03; + let t_scale = 1.0; + let p_x: f64 = 0.5 * (1.0 - f64::exp(-2.0 * lambda_x * t_scale)); + let p_z: f64 = 0.5 * (1.0 - f64::exp(-2.0 * lambda_z * t_scale)); + + let model = PauliLindbladModel::new( + vec![ + PauliString::single(Pauli1::X), + PauliString::single(Pauli1::Z), + ], + vec![lambda_x, lambda_z], + ); + + let n_samples: usize = 200_000; + let mut rng = StdRng::seed_from_u64(7); + // Bucket counts: [I, X, Y, Z]. Note X*Z (unordered) = Y in our + // sign-dropped multiplication table. + let mut counts = [0usize; 4]; + for _ in 0..n_samples { + let s = model.sample(t_scale, &mut rng); + let idx = match s.0[0] { + Pauli1::I => 0, + Pauli1::X => 1, + Pauli1::Y => 2, + Pauli1::Z => 3, + }; + counts[idx] += 1; + } + let emp = |k: usize| counts[k] as f64 / n_samples as f64; + + // Analytical: + // P(I) = (1-p_x)(1-p_z) + // P(X) = p_x (1 - p_z) + // P(Z) = (1 - p_x) p_z + // P(Y) = p_x p_z + let e_i = (1.0 - p_x) * (1.0 - p_z); + let e_x = p_x * (1.0 - p_z); + let e_z = (1.0 - p_x) * p_z; + let e_y = p_x * p_z; + + for (idx, expected) in [(0, e_i), (1, e_x), (2, e_y), (3, e_z)] { + let got = emp(idx); + let sigma = (expected * (1.0 - expected) / n_samples as f64).sqrt(); + let tol = 5.0 * sigma; + assert!( + (got - expected).abs() < tol, + "bucket {}: got {}, expected {}, diff {} > 5 sigma {}", + idx, + got, + expected, + (got - expected).abs(), + tol, + ); + } +} diff --git a/exp/pecos-lindblad/tests/walsh_hadamard_roundtrip.rs b/exp/pecos-lindblad/tests/walsh_hadamard_roundtrip.rs new file mode 100644 index 000000000..836630ee7 --- /dev/null +++ b/exp/pecos-lindblad/tests/walsh_hadamard_roundtrip.rs @@ -0,0 +1,117 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Walsh-Hadamard forward/inverse consistency. Starting from arbitrary +//! non-negative rates `{lambda_k}`: +//! +//! 1. Forward map: `alpha_b = 2 * sum_k lambda_k * _sp`. +//! 2. Invert via Walsh-Hadamard: `lambda'_k = -(1/4^n) * sum_b (-1)^{_sp} * alpha_b`. +//! 3. Verify `lambda'_k == lambda_k` (self-consistency of the algorithm). +//! +//! This closes a gap in the existing coverage: paper-fixture tests verify +//! the round-trip end-to-end but not the Walsh-Hadamard step in isolation, +//! so a bug there could cancel against a parallel bug in synthesis. + +use approx::assert_abs_diff_eq; + +use pecos_lindblad::{Pauli1, PauliLindbladModel, PauliString}; + +fn forward_alpha(model: &PauliLindbladModel, b: &PauliString) -> f64 { + // alpha_b = 2 * sum_k lambda_k * _sp. + model + .supports + .iter() + .zip(&model.rates) + .map(|(k, lam)| 2.0 * lam * f64::from(b.symplectic_product(k))) + .sum() +} + +fn inverse_walsh_hadamard( + paulis: &[PauliString], + alphas: &[f64], + n_qubits: usize, +) -> Vec { + // lambda_k = -(1/4^n) * sum_b (-1)^{_sp} * alpha_b (paper App B). + let norm = 1.0 / (1usize << (2 * n_qubits)) as f64; + paulis + .iter() + .map(|k| { + let s: f64 = paulis + .iter() + .zip(alphas.iter()) + .map(|(b, &ab)| { + let sign = if k.symplectic_product(b) == 0 { 1.0 } else { -1.0 }; + sign * ab + }) + .sum(); + -norm * s + }) + .collect() +} + +fn round_trip(n_qubits: usize, seed_rates: &[(&str, f64)]) { + let supports: Vec = seed_rates + .iter() + .map(|(s, _)| PauliString::from_str(s).unwrap()) + .collect(); + let rates: Vec = seed_rates.iter().map(|(_, r)| *r).collect(); + let model = PauliLindbladModel::new(supports.clone(), rates.clone()); + + // Enumerate all non-identity paulis to get alpha_b for each. + let all = PauliString::enumerate_nonidentity(n_qubits); + let alphas: Vec = all.iter().map(|b| forward_alpha(&model, b)).collect(); + let recovered = inverse_walsh_hadamard(&all, &alphas, n_qubits); + + // Build the "true" rates aligned to `all` order (0 for unseeded supports). + let mut expected = vec![0.0; all.len()]; + for (s, r) in &rates.iter().zip(&supports).map(|(r, s)| (s.clone(), *r)).collect::>() { + if let Some(idx) = all.iter().position(|p| p == s) { + expected[idx] = *r; + } + } + for (got, want) in recovered.iter().zip(expected.iter()) { + assert_abs_diff_eq!(got, want, epsilon = 1e-12); + } +} + +#[test] +fn walsh_hadamard_round_trip_1q() { + round_trip(1, &[("X", 0.001), ("Y", 0.002), ("Z", 0.003)]); +} + +#[test] +fn walsh_hadamard_round_trip_2q_sparse() { + round_trip( + 2, + &[ + ("IX", 1e-3), + ("IZ", 2e-3), + ("XI", 3e-3), + ("ZZ", 4e-4), + ], + ); +} + +#[test] +fn walsh_hadamard_round_trip_3q_with_weight_3() { + round_trip( + 3, + &[("IYZ", 1e-4), ("IZZ", 2e-4), ("ZZZ", 5e-5), ("XII", 1e-3)], + ); +} + +#[test] +fn walsh_hadamard_round_trip_dense_1q() { + // Dense 1Q (all 3 non-identity rates set) to exercise every row. + let _ = Pauli1::X; // re-export reachable + round_trip(1, &[("X", 0.1), ("Y", 0.2), ("Z", 0.3)]); +} From 92562d80fe1a9fa5c7ccd5c5ec705c19976278f3 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 11:51:39 -0600 Subject: [PATCH 029/125] Verification gap 8: property-based invariants with proptest --- Cargo.lock | 1 + exp/pecos-lindblad/Cargo.toml | 1 + .../tests/proptest_invariants.rs | 109 ++++++++++++++++++ 3 files changed, 111 insertions(+) create mode 100644 exp/pecos-lindblad/tests/proptest_invariants.rs diff --git a/Cargo.lock b/Cargo.lock index d64b919f4..7a9e13bff 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -3902,6 +3902,7 @@ dependencies = [ "num-complex 0.4.6", "pecos-qec", "pecos-quantum", + "proptest", "rand 0.10.0", "serde", "serde_json", diff --git a/exp/pecos-lindblad/Cargo.toml b/exp/pecos-lindblad/Cargo.toml index b3a1365de..58d384e14 100644 --- a/exp/pecos-lindblad/Cargo.toml +++ b/exp/pecos-lindblad/Cargo.toml @@ -28,5 +28,6 @@ serde = { workspace = true, optional = true } approx = "0.5" pecos-qec.workspace = true pecos-quantum.workspace = true +proptest = "1.4" rand.workspace = true serde_json.workspace = true diff --git a/exp/pecos-lindblad/tests/proptest_invariants.rs b/exp/pecos-lindblad/tests/proptest_invariants.rs new file mode 100644 index 000000000..20a529786 --- /dev/null +++ b/exp/pecos-lindblad/tests/proptest_invariants.rs @@ -0,0 +1,109 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Property-based invariants via proptest. Generates random Lindbladians +//! and verifies: +//! +//! 1. All synthesized PL rates are non-negative (positivity). +//! 2. At τ_g → 0, all rates vanish (no-time, no-error). +//! 3. Rates scale linearly with τ_g at leading order in weak noise. +//! 4. Walsh-Hadamard forward/inverse is a bijection on rate vectors. + +use proptest::prelude::*; + +use pecos_lindblad::noise_models::ad_pd_1q; +use pecos_lindblad::{ + synthesize_identity_1q, Gate, Pauli1, PauliLindbladModel, PauliString, +}; + +/// Generate physical `(T_1, T_2)` with `T_2 <= 2 T_1` (GKS-positive regime). +fn t1_t2_strategy() -> impl Strategy { + (10.0f64..1000.0, 0.01f64..1.0).prop_map(|(t1, t2_ratio)| (t1, t2_ratio * 2.0 * t1)) +} + +proptest! { + #![proptest_config(ProptestConfig { cases: 64, ..ProptestConfig::default() })] + + #[test] + fn identity_1q_rates_non_negative((t1, t2) in t1_t2_strategy(), tau_g in 0.01f64..50.0) { + let noise = ad_pd_1q(t1, t2); + let gate = Gate::identity(1, noise, tau_g); + let pl = synthesize_identity_1q(&gate); + for p in [Pauli1::X, Pauli1::Y, Pauli1::Z] { + let r = pl.rate(&PauliString::single(p)); + prop_assert!(r >= 0.0, "rate for {:?} was negative: {}", p, r); + } + } + + #[test] + fn identity_1q_rates_linear_in_tau( + (t1, t2) in t1_t2_strategy(), + tau_a in 0.01f64..5.0, + ) { + let tau_b = tau_a * 2.0; + let noise_a = ad_pd_1q(t1, t2); + let noise_b = ad_pd_1q(t1, t2); + let pl_a = synthesize_identity_1q(&Gate::identity(1, noise_a, tau_a)); + let pl_b = synthesize_identity_1q(&Gate::identity(1, noise_b, tau_b)); + for p in [Pauli1::X, Pauli1::Y, Pauli1::Z] { + let ra = pl_a.rate(&PauliString::single(p)); + let rb = pl_b.rate(&PauliString::single(p)); + // Identity+AD+PD is exact closed form with lambda_k ∝ tau_g. + prop_assert!( + (rb - 2.0 * ra).abs() < 1e-12, + "rate for {:?} not linear in tau: ra={}, rb={}", + p, ra, rb, + ); + } + } +} + +proptest! { + #![proptest_config(ProptestConfig { cases: 32, ..ProptestConfig::default() })] + + /// Generate a random non-negative rate vector and verify the forward + /// Walsh-Hadamard map reproduces alpha_b = 2 Σ λ_k ⟨b,k⟩_sp. + #[test] + fn walsh_hadamard_forward_is_linear_in_rates( + lam_x in 0.0f64..0.1, + lam_y in 0.0f64..0.1, + lam_z in 0.0f64..0.1, + ) { + // Forward relation alpha_b = 2 Σ_k λ_k ⟨b,k⟩_sp for n=1. + // alpha_X = 2(lam_y + lam_z) + // alpha_Y = 2(lam_x + lam_z) + // alpha_Z = 2(lam_x + lam_y) + let supports = vec![ + PauliString::single(Pauli1::X), + PauliString::single(Pauli1::Y), + PauliString::single(Pauli1::Z), + ]; + let rates = vec![lam_x, lam_y, lam_z]; + let model = PauliLindbladModel::new(supports, rates); + + let alpha = |b: &PauliString| -> f64 { + model + .supports + .iter() + .zip(&model.rates) + .map(|(k, lam)| 2.0 * lam * f64::from(b.symplectic_product(k))) + .sum() + }; + + let x = PauliString::single(Pauli1::X); + let y = PauliString::single(Pauli1::Y); + let z = PauliString::single(Pauli1::Z); + prop_assert!((alpha(&x) - 2.0 * (lam_y + lam_z)).abs() < 1e-14); + prop_assert!((alpha(&y) - 2.0 * (lam_x + lam_z)).abs() < 1e-14); + prop_assert!((alpha(&z) - 2.0 * (lam_x + lam_y)).abs() < 1e-14); + } +} From a5b0949a5f4852ee279ce7a6f314229391dc540a Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 11:59:21 -0600 Subject: [PATCH 030/125] Limit fix F1: PauliLindbladModel diff/residual/diagnose helpers for validation --- exp/pecos-lindblad/src/pauli_lindblad.rs | 91 ++++++++++++++++++++++++ exp/pecos-lindblad/tests/diff_helpers.rs | 88 +++++++++++++++++++++++ 2 files changed, 179 insertions(+) create mode 100644 exp/pecos-lindblad/tests/diff_helpers.rs diff --git a/exp/pecos-lindblad/src/pauli_lindblad.rs b/exp/pecos-lindblad/src/pauli_lindblad.rs index f7ad43f48..b16fa227d 100644 --- a/exp/pecos-lindblad/src/pauli_lindblad.rs +++ b/exp/pecos-lindblad/src/pauli_lindblad.rs @@ -63,6 +63,97 @@ impl PauliLindbladModel { self.rates.iter().copied().fold(0.0, f64::max) } + /// Per-Pauli residual `self - other`. Returns a vector of + /// `(pauli, self_rate, other_rate, residual)` for every Pauli in the + /// union of the two models' supports. + pub fn diff(&self, other: &Self) -> Vec<(PauliString, f64, f64, f64)> { + use std::collections::HashSet; + let mut all: HashSet = HashSet::new(); + for p in self.supports.iter().chain(other.supports.iter()) { + all.insert(p.clone()); + } + let mut out: Vec<_> = all + .into_iter() + .map(|p| { + let a = self.rate(&p); + let b = other.rate(&p); + (p, a, b, a - b) + }) + .collect(); + out.sort_by(|(_, _, _, x), (_, _, _, y)| { + y.abs().partial_cmp(&x.abs()).unwrap_or(std::cmp::Ordering::Equal) + }); + out + } + + /// `L2` norm of the rate-residual vector between `self` and `other`. + pub fn residual_l2(&self, other: &Self) -> f64 { + self.diff(other).iter().map(|(_, _, _, r)| r * r).sum::().sqrt() + } + + /// Pauli with the largest absolute residual against `other`. Returns + /// `None` if both models are empty. + pub fn max_residual(&self, other: &Self) -> Option<(PauliString, f64)> { + self.diff(other).into_iter().next().map(|(p, _, _, r)| (p, r)) + } + + /// Aggregate absolute residual by Pauli weight. Returns `weight -> sum + /// of |residual|`. Useful for diagnosing which weight class of physics + /// is missing from the model (e.g. weight-2 residual large => + /// correlated two-qubit noise missing). + pub fn residual_by_weight(&self, other: &Self) -> Vec<(usize, f64)> { + use std::collections::BTreeMap; + let mut agg: BTreeMap = BTreeMap::new(); + for (p, _, _, r) in self.diff(other) { + *agg.entry(p.weight()).or_insert(0.0) += r.abs(); + } + agg.into_iter().collect() + } + + /// Heuristic diagnostic: given a predicted model (`self`) and a + /// measured model (`other`), suggest physical sources likely missing + /// from the prediction. Returns human-readable strings ordered by + /// residual magnitude. Thresholds are intentionally coarse; use as a + /// starting point, not a final verdict. + pub fn diagnose_gap(&self, other: &Self, tol: f64) -> Vec { + let mut msgs = Vec::new(); + let by_weight = self.residual_by_weight(other); + + for (weight, total_abs) in &by_weight { + if *total_abs < tol { + continue; + } + match weight { + 1 => msgs.push(format!( + "weight-1 residual {:.3e}: suggests missing incoherent single-qubit noise \ + (T_1, T_phi mis-characterized, or extra dephasing/relaxation channels)", + total_abs + )), + 2 => msgs.push(format!( + "weight-2 residual {:.3e}: suggests correlated 2-qubit noise not in model \ + (coherent ZZ crosstalk, leakage-induced correlations, or gate mis-calibration)", + total_abs + )), + w if *w >= 3 => msgs.push(format!( + "weight-{} residual {:.3e}: high-weight residual; suggests multi-qubit \ + crosstalk or higher-order Magnus corrections needed", + w, total_abs + )), + _ => {} + } + } + // Highlight the single worst Pauli as a concrete pointer. + if let Some((p, r)) = self.max_residual(other) { + if r.abs() >= tol { + msgs.push(format!( + "largest per-Pauli residual: |lambda_{{{}}}^pred - lambda_{{{}}}^meas| = {:.3e}", + p, p, r + )); + } + } + msgs + } + /// Sample an error realization over integrated duration `t_scale`: /// each Pauli term independently fires with probability /// `p_k = (1 - exp(-2 * lambda_k * t_scale)) / 2`. Returns the diff --git a/exp/pecos-lindblad/tests/diff_helpers.rs b/exp/pecos-lindblad/tests/diff_helpers.rs new file mode 100644 index 000000000..8f7ecf5a6 --- /dev/null +++ b/exp/pecos-lindblad/tests/diff_helpers.rs @@ -0,0 +1,88 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Tests for validation-oriented diff helpers on `PauliLindbladModel`. + +use approx::assert_abs_diff_eq; + +use pecos_lindblad::{PauliLindbladModel, PauliString}; + +fn model(entries: &[(&str, f64)]) -> PauliLindbladModel { + let supports: Vec<_> = entries.iter().map(|(s, _)| PauliString::from_str(s).unwrap()).collect(); + let rates: Vec<_> = entries.iter().map(|(_, r)| *r).collect(); + PauliLindbladModel::new(supports, rates) +} + +#[test] +fn diff_is_sorted_by_absolute_residual() { + let pred = model(&[("IX", 0.001), ("IZ", 0.005), ("XI", 0.002)]); + let meas = model(&[("IX", 0.0012), ("IZ", 0.008), ("XI", 0.002)]); + let d = pred.diff(&meas); + // IZ has largest absolute residual (0.003), IX next (0.0002), XI last (0). + assert_eq!(format!("{}", d[0].0), "IZ"); + assert_eq!(format!("{}", d[1].0), "IX"); + assert_eq!(format!("{}", d[2].0), "XI"); + assert_abs_diff_eq!(d[0].3, -0.003, epsilon = 1e-12); +} + +#[test] +fn residual_l2_and_max() { + let a = model(&[("X", 0.01), ("Y", 0.02), ("Z", 0.03)]); + let b = model(&[("X", 0.02), ("Y", 0.00), ("Z", 0.03)]); + // Differences: X=-0.01, Y=+0.02, Z=0. L2 = sqrt(0.0001 + 0.0004) = sqrt(5)*0.01. + assert_abs_diff_eq!(a.residual_l2(&b), (5.0_f64).sqrt() * 0.01, epsilon = 1e-12); + let (worst_p, worst_r) = a.max_residual(&b).unwrap(); + assert_eq!(format!("{}", worst_p), "Y"); + assert_abs_diff_eq!(worst_r, 0.02, epsilon = 1e-12); +} + +#[test] +fn residual_by_weight_classifies_correctly() { + let a = model(&[("IX", 0.001), ("IY", 0.001), ("ZZ", 0.005), ("IZZ", 0.002)]); + let b = model(&[("IX", 0.002), ("IY", 0.001), ("ZZ", 0.009), ("IZZ", 0.0025)]); + let by_w = a.residual_by_weight(&b); + // Differences: IX=-0.001 (wt 1), IY=0 (wt 1), ZZ=-0.004 (wt 2), IZZ=-0.0005 (wt 2). + let w1 = by_w.iter().find(|(w, _)| *w == 1).unwrap().1; + let w2 = by_w.iter().find(|(w, _)| *w == 2).unwrap().1; + assert_abs_diff_eq!(w1, 0.001, epsilon = 1e-12); + assert_abs_diff_eq!(w2, 0.0045, epsilon = 1e-12); +} + +#[test] +fn diagnose_flags_large_weight_2_residual() { + let pred = model(&[("IX", 0.001), ("IZ", 0.005)]); + let meas = model(&[("IX", 0.001), ("IZ", 0.005), ("ZZ", 0.01)]); + // Predicted model missing ZZ -- diagnose should flag weight-2 residual. + let diagnoses = pred.diagnose_gap(&meas, 1e-5); + assert!(diagnoses.iter().any(|m| m.contains("weight-2")), "expected weight-2 diagnosis in {:?}", diagnoses); + assert!(diagnoses.iter().any(|m| m.contains("ZZ")), "expected ZZ mention in {:?}", diagnoses); +} + +#[test] +fn diagnose_quiet_when_models_agree() { + let pred = model(&[("X", 0.001), ("Z", 0.002)]); + let meas = model(&[("X", 0.001), ("Z", 0.002)]); + let diagnoses = pred.diagnose_gap(&meas, 1e-10); + assert!(diagnoses.is_empty(), "expected no diagnoses, got {:?}", diagnoses); +} + +#[test] +fn union_of_supports_considered() { + // a has X, b has Z; diff should include both with appropriate zero. + let a = model(&[("X", 0.003)]); + let b = model(&[("Z", 0.005)]); + let d = a.diff(&b); + assert_eq!(d.len(), 2); + // Largest |residual| is Z = 0 - 0.005 = -0.005. + assert_eq!(format!("{}", d[0].0), "Z"); + assert_abs_diff_eq!(d[0].3, -0.005, epsilon = 1e-12); +} From d709be8d7f92263ef5a7473f7126e515d030bba7 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 12:01:21 -0600 Subject: [PATCH 031/125] Limit fix F2: superop synthesis path for mixed coherent+dissipative noise --- exp/pecos-lindblad/src/lib.rs | 2 +- exp/pecos-lindblad/src/lindbladian.rs | 52 +++++++ exp/pecos-lindblad/src/matrix.rs | 59 ++++++++ exp/pecos-lindblad/src/synthesis.rs | 52 +++++++ exp/pecos-lindblad/tests/superop_synthesis.rs | 129 ++++++++++++++++++ 5 files changed, 293 insertions(+), 1 deletion(-) create mode 100644 exp/pecos-lindblad/tests/superop_synthesis.rs diff --git a/exp/pecos-lindblad/src/lib.rs b/exp/pecos-lindblad/src/lib.rs index 14ad16b1d..fb83d8ddd 100644 --- a/exp/pecos-lindblad/src/lib.rs +++ b/exp/pecos-lindblad/src/lib.rs @@ -86,5 +86,5 @@ pub use lindbladian::Lindbladian; pub use pauli_lindblad::PauliLindbladModel; pub use synthesis::{ synthesize_exact_unitary, synthesize_identity_1q, synthesize_numerical, - synthesize_numerical_1q, DEFAULT_N_STEPS, + synthesize_numerical_1q, synthesize_superop_identity, DEFAULT_N_STEPS, }; diff --git a/exp/pecos-lindblad/src/lindbladian.rs b/exp/pecos-lindblad/src/lindbladian.rs index d4e81cd76..0404e4741 100644 --- a/exp/pecos-lindblad/src/lindbladian.rs +++ b/exp/pecos-lindblad/src/lindbladian.rs @@ -45,6 +45,58 @@ impl Lindbladian { Self { d, hamiltonian: matrix::zeros(d), collapse: Vec::new() } } + /// Build the `d^2 x d^2` Liouville-superoperator matrix representation + /// of `L`. Column-stacking convention: `vec(L(rho)) = L_super * vec(rho)`. + /// + /// `L(rho) = -i[H, rho] + sum_j gamma_j * ( c_j rho c_j^dag + /// - 1/2 {c_j^dag c_j, rho} )` + /// translates to: + /// + /// `L_super = -i (I ⊗ H - H^T ⊗ I) + /// + sum_j gamma_j * ( conj(c_j) ⊗ c_j + /// - 1/2 I ⊗ c_j^dag c_j + /// - 1/2 (c_j^dag c_j)^T ⊗ I )` + /// + /// (Note `(c^dag)^T = conj(c)`.) + pub fn superoperator(&self) -> Matrix { + let d = self.d; + let d2 = d * d; + let id = matrix::identity(d); + let neg_i = Complex64::new(0.0, -1.0); + + // Hamiltonian part: -i (I ⊗ H - H^T ⊗ I). + let h_t = matrix::transpose(&self.hamiltonian, d); + let coh = matrix::sub( + &matrix::kron(&id, &self.hamiltonian, d, d), + &matrix::kron(&h_t, &id, d, d), + ); + let mut l_super = matrix::scale(&coh, neg_i); + + for (c, gamma) in &self.collapse { + let c_bar = matrix::conj(c); + let c_dag = matrix::dag(c, d); + let cdag_c = matrix::matmul(&c_dag, c, d); + let cdag_c_t = matrix::transpose(&cdag_c, d); + + // gamma * ( c_bar ⊗ c - 1/2 I ⊗ c^dag c - 1/2 (c^dag c)^T ⊗ I ) + let term_a = matrix::kron(&c_bar, c, d, d); + let term_b = matrix::kron(&id, &cdag_c, d, d); + let term_c = matrix::kron(&cdag_c_t, &id, d, d); + let inner = matrix::sub( + &term_a, + &matrix::add( + &matrix::scale(&term_b, Complex64::new(0.5, 0.0)), + &matrix::scale(&term_c, Complex64::new(0.5, 0.0)), + ), + ); + let scaled = matrix::scale(&inner, Complex64::new(*gamma, 0.0)); + l_super = matrix::add(&l_super, &scaled); + } + + assert_eq!(l_super.len(), d2 * d2); + l_super + } + /// Apply `L` to a matrix `rho`. Returns `L(rho)`. pub fn apply(&self, rho: &Matrix) -> Matrix { let d = self.d; diff --git a/exp/pecos-lindblad/src/matrix.rs b/exp/pecos-lindblad/src/matrix.rs index ba7344dae..d9c60deaf 100644 --- a/exp/pecos-lindblad/src/matrix.rs +++ b/exp/pecos-lindblad/src/matrix.rs @@ -61,6 +61,22 @@ pub fn dag(a: &Matrix, d: usize) -> Matrix { b } +/// Plain transpose (no complex conjugation). +pub fn transpose(a: &Matrix, d: usize) -> Matrix { + let mut b = zeros(d); + for i in 0..d { + for j in 0..d { + b[j * d + i] = a[i * d + j]; + } + } + b +} + +/// Element-wise complex conjugate. +pub fn conj(a: &Matrix) -> Matrix { + a.iter().map(|c| c.conj()).collect() +} + pub fn trace(a: &Matrix, d: usize) -> Complex64 { (0..d).map(|i| a[i * d + i]).sum() } @@ -284,6 +300,49 @@ pub fn inf_norm(a: &Matrix, d: usize) -> f64 { .fold(0.0, f64::max) } +/// Column-stack vectorization `vec(M)` of a `d x d` matrix (length `d^2`). +/// Convention: `vec(A rho B) = (B^T ⊗ A) vec(rho)`. +pub fn vec_of(m: &Matrix, d: usize) -> Vec { + assert_eq!(m.len(), d * d); + let mut out = vec![Complex64::new(0.0, 0.0); d * d]; + // Column-major layout: vec(M)[i + d*j] = M[i, j] = m[i*d + j]. + for i in 0..d { + for j in 0..d { + out[i + d * j] = m[i * d + j]; + } + } + out +} + +/// Inverse of [`vec_of`]: reshape a `d^2` vector back to a `d x d` +/// matrix (row-major storage). +pub fn unvec(v: &[Complex64], d: usize) -> Matrix { + assert_eq!(v.len(), d * d); + let mut m = vec![Complex64::new(0.0, 0.0); d * d]; + for i in 0..d { + for j in 0..d { + m[i * d + j] = v[i + d * j]; + } + } + m +} + +/// Matrix-vector product `A * v` for a `n x n` matrix `A` and length-`n` +/// vector `v`. +pub fn matvec(a: &Matrix, v: &[Complex64], n: usize) -> Vec { + assert_eq!(a.len(), n * n); + assert_eq!(v.len(), n); + let mut out = vec![Complex64::new(0.0, 0.0); n]; + for i in 0..n { + let mut s = Complex64::new(0.0, 0.0); + for j in 0..n { + s += a[i * n + j] * v[j]; + } + out[i] = s; + } + out +} + /// Matrix exponential `exp(-i * H * t)` for a 2x2 traceless Hermitian H. /// Uses the Bloch form: `exp(-i H t) = cos(r t) I - i sin(r t) H / r` /// where `r = sqrt(c_x^2 + c_y^2 + c_z^2)` is the Pauli-decomposition norm. diff --git a/exp/pecos-lindblad/src/synthesis.rs b/exp/pecos-lindblad/src/synthesis.rs index ba011fb8f..55adda857 100644 --- a/exp/pecos-lindblad/src/synthesis.rs +++ b/exp/pecos-lindblad/src/synthesis.rs @@ -65,6 +65,58 @@ pub fn synthesize_numerical_1q(gate: &Gate, n_steps: usize) -> PauliLindbladMode synthesize_numerical(gate, n_steps) } +/// Synthesize a Pauli-Lindblad model from **mixed coherent + dissipative +/// noise** on a time-independent ideal Hamiltonian (currently: identity +/// gate, `H_g = 0`) via the full Lindblad superoperator path. +/// +/// Builds `L_super` (`d^2 x d^2`), exponentiates to get the channel +/// `exp(L_super * tau_g)`, applies to each `vec(P_b)`, extracts Pauli +/// fidelity `f_b = (1/d) tr(P_b * Lambda(P_b))`, then inverts via +/// Walsh-Hadamard. Unifies the coherent and dissipative paths for the +/// identity case: matches [`synthesize_identity_1q`] for pure AD+PD, +/// matches [`synthesize_exact_unitary`] for pure coherent noise on +/// identity, and handles **both at once** (the case the other paths +/// reject). +/// +/// Requires `gate.ideal.hamiltonian` to be (numerically) zero -- for +/// non-trivial `H_g` the interaction-frame Lindbladian is time-dependent +/// and requires either Magnus order >= 1 time-ordering (existing +/// `synthesize_numerical` path for linear-order dissipative) or +/// time-slicing (future work). +pub fn synthesize_superop_identity(gate: &Gate) -> PauliLindbladModel { + let n = gate.num_qubits; + let d = 1usize << n; + assert!( + is_zero_matrix(&gate.ideal.hamiltonian), + "synthesize_superop_identity requires H_g = 0 (time-independent L_I)" + ); + let tau = gate.tau_g; + let l_super = gate.noise.superoperator(); + // channel = exp(L_super * tau_g) + let channel = matrix::expm(&matrix::scale(&l_super, Complex64::new(tau, 0.0)), d * d); + + let paulis = PauliString::enumerate_nonidentity(n); + let alphas: Vec = paulis + .iter() + .map(|p| { + let p_mat = matrix::pauli_string_mat(p); + let vec_p = matrix::vec_of(&p_mat, d); + let vec_applied = matrix::matvec(&channel, &vec_p, d * d); + let applied = matrix::unvec(&vec_applied, d); + let inner = matrix::trace(&matrix::matmul(&p_mat, &applied, d), d); + let f_b = inner.re / d as f64; + assert!( + f_b > 0.1, + "Pauli fidelity {} too low for {:?}; noise outside weak-coupling regime", + f_b, + p, + ); + -f_b.ln() + }) + .collect(); + model_from_alphas_walsh(paulis, alphas, n) +} + /// Synthesize a Pauli-Lindblad model for a gate with **purely coherent /// noise** (no collapse operators) via the exact error-unitary path. /// diff --git a/exp/pecos-lindblad/tests/superop_synthesis.rs b/exp/pecos-lindblad/tests/superop_synthesis.rs new file mode 100644 index 000000000..419766b01 --- /dev/null +++ b/exp/pecos-lindblad/tests/superop_synthesis.rs @@ -0,0 +1,129 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Tests for `synthesize_superop_identity` -- the unified path for +//! identity gates with mixed coherent + dissipative noise. Validates +//! consistency with: +//! +//! - `synthesize_identity_1q` (pure dissipative AD+PD) +//! - `synthesize_exact_unitary` (pure coherent) +//! +//! and exercises the **new** mixed case (both at once) that the other two +//! entry points reject or under-model. + +use approx::assert_abs_diff_eq; +use num_complex::Complex64; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::noise_models::{ad_pd_1q, coherent_phase_2q}; +use pecos_lindblad::{ + synthesize_exact_unitary, synthesize_identity_1q, synthesize_superop_identity, Gate, + Lindbladian, Pauli1, PauliString, +}; + +#[test] +fn superop_identity_matches_fast_ad_pd_1q() { + // Pure AD+PD, 1Q identity. Superop path should match fast closed-form + // path to machine precision. + let t1 = 100.0; + let t2 = 80.0; + let tau_g = 5.0; + let noise = ad_pd_1q(t1, t2); + let gate = Gate::identity(1, noise, tau_g); + + let fast = synthesize_identity_1q(&gate); + let superop = synthesize_superop_identity(&gate); + + for p in [Pauli1::X, Pauli1::Y, Pauli1::Z] { + let key = PauliString::single(p); + assert_abs_diff_eq!(fast.rate(&key), superop.rate(&key), epsilon = 1e-10); + } +} + +#[test] +fn superop_identity_matches_exact_unitary_for_pure_coherent() { + // 2Q identity with pure coherent phase noise: both exact_unitary and + // superop paths should agree. + let tau_g = 10.0; + let delta_iz = 1e-5; + let delta_zi = 2e-5; + let delta_zz = 5e-6; + let noise = coherent_phase_2q(delta_iz, delta_zi, delta_zz); + let gate = Gate::identity(2, noise, tau_g); + + let exact = synthesize_exact_unitary(&gate); + let superop = synthesize_superop_identity(&gate); + + for ps in PauliString::enumerate_nonidentity(2) { + assert_abs_diff_eq!(exact.rate(&ps), superop.rate(&ps), epsilon = 1e-10); + } +} + +#[test] +fn superop_identity_handles_mixed_coherent_and_dissipative_2q() { + // THE new capability: simultaneous AD+PD AND coherent crosstalk on + // an identity gate. Neither `synthesize_identity_1q` (1Q only) nor + // `synthesize_exact_unitary` (coherent only) can handle this; + // `synthesize_numerical` catches only the Omega_1 dissipative part. + // Only `synthesize_superop_identity` gives the full answer. + let d = 4; + let tau_g = 1.0; + let beta_down = 1e-4; + let beta_phi = 2e-4; + let delta_zz = 1e-3; + + // Hamiltonian part: (delta_zz / 2) ZZ coherent + let i2 = matrix::identity(2); + let z = matrix::pauli_1q(Pauli1::Z); + let zz = matrix::kron(&z, &z, 2, 2); + let h_delta = matrix::scale(&zz, Complex64::new(delta_zz / 2.0, 0.0)); + + // Dissipator part: AD+PD on both qubits + let sm = matrix::sigma_minus(); + let sm_l = matrix::kron(&sm, &i2, 2, 2); + let sm_r = matrix::kron(&i2, &sm, 2, 2); + let z_l = matrix::kron(&z, &i2, 2, 2); + let z_r = matrix::kron(&i2, &z, 2, 2); + let collapse: Vec<(Matrix, f64)> = vec![ + (sm_l, beta_down), + (sm_r, beta_down), + (z_l, beta_phi / 2.0), + (z_r, beta_phi / 2.0), + ]; + let mixed = Lindbladian::new(d, h_delta, collapse); + let gate = Gate::identity(2, mixed, tau_g); + let pl = synthesize_superop_identity(&gate); + + let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + + // Expected (leading-order superposition of independent contributions): + // Dissipative (AD+PD) on each qubit contributes single-qubit rates + // (paper line 812): lambda_{i·x,y} = beta_down * tau / 4, + // lambda_{i·z} = beta_phi * tau / 2 (mirror for l). + // Coherent ZZ contributes lambda_ZZ = (delta_zz * tau)^2 / 4 + // (paper eq. 981 identity case). + // Cross terms between dissipative and coherent are O(beta * delta * tau^2) + // and small for these parameter values. + let expected_ix_iy = beta_down * tau_g / 4.0; + let expected_iz = beta_phi * tau_g / 2.0; + let expected_zz = (delta_zz * tau_g).powi(2) / 4.0; + let tol_dissipative = 1e-10; + let tol_coherent = 1e-10; + + assert_abs_diff_eq!(rate("IX"), expected_ix_iy, epsilon = tol_dissipative); + assert_abs_diff_eq!(rate("IY"), expected_ix_iy, epsilon = tol_dissipative); + assert_abs_diff_eq!(rate("XI"), expected_ix_iy, epsilon = tol_dissipative); + assert_abs_diff_eq!(rate("YI"), expected_ix_iy, epsilon = tol_dissipative); + assert_abs_diff_eq!(rate("IZ"), expected_iz, epsilon = tol_dissipative); + assert_abs_diff_eq!(rate("ZI"), expected_iz, epsilon = tol_dissipative); + assert_abs_diff_eq!(rate("ZZ"), expected_zz, epsilon = tol_coherent); +} From cfc733a7ffb40f7ffda10d1950a15b70d334a48f Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 12:03:40 -0600 Subject: [PATCH 032/125] Limit fix F3: Monte Carlo uncertainty propagation for (T1, T2) inputs --- exp/pecos-lindblad/src/noise_models.rs | 94 +++++++++++++ .../tests/uncertainty_propagation.rs | 123 ++++++++++++++++++ 2 files changed, 217 insertions(+) create mode 100644 exp/pecos-lindblad/tests/uncertainty_propagation.rs diff --git a/exp/pecos-lindblad/src/noise_models.rs b/exp/pecos-lindblad/src/noise_models.rs index 612d5ca4f..451865f5c 100644 --- a/exp/pecos-lindblad/src/noise_models.rs +++ b/exp/pecos-lindblad/src/noise_models.rs @@ -110,6 +110,100 @@ pub fn coherent_phase_2q(delta_iz: f64, delta_zi: f64, delta_zz: f64) -> Lindbla Lindbladian::new(d, h_delta, Vec::new()) } +/// Per-Pauli mean + standard-deviation statistics from a Monte-Carlo +/// uncertainty propagation. +#[derive(Clone, Debug, Default)] +pub struct RateUncertainty { + pub paulis: Vec, + /// `means[i]` = mean of `rates[i]` across MC samples. + pub means: Vec, + /// `stds[i]` = sample standard deviation of `rates[i]`. + pub stds: Vec, + /// Number of samples drawn. + pub n_samples: usize, +} + +/// Propagate parameter uncertainty into the Pauli-Lindblad rates by +/// Monte-Carlo sampling. +/// +/// `synthesize_sample` is called once per MC draw. The user builds the +/// `Gate` from the (possibly jittered) parameters and returns the +/// synthesized [`PauliLindbladModel`]. This routine aggregates across +/// draws: per-Pauli sample mean + sample standard deviation. +/// +/// The first sample determines the support enumeration; later samples +/// are matched by support equality, so stochastic supports (same Pauli +/// but generated in a different order) are fine. +pub fn propagate_uncertainty( + n_samples: usize, + mut synthesize_sample: impl FnMut(usize) -> crate::PauliLindbladModel, +) -> RateUncertainty { + assert!(n_samples >= 2, "need >=2 samples to compute std"); + + // Use the first sample to fix the Pauli set. + let first = synthesize_sample(0); + let n_p = first.supports.len(); + let mut sum = first.rates.clone(); + let mut sum_sq: Vec = first.rates.iter().map(|r| r * r).collect(); + + for k in 1..n_samples { + let model = synthesize_sample(k); + assert_eq!( + model.supports.len(), + n_p, + "MC draw {}: support size {} != expected {}", + k, + model.supports.len(), + n_p, + ); + for (i, p) in first.supports.iter().enumerate() { + let r = model.rate(p); + sum[i] += r; + sum_sq[i] += r * r; + } + } + + let n = n_samples as f64; + let means: Vec = sum.iter().map(|s| s / n).collect(); + let stds: Vec = sum_sq + .iter() + .zip(means.iter()) + .map(|(ss, m)| { + let var = (ss / n - m * m).max(0.0); + var.sqrt() + }) + .collect(); + + RateUncertainty { + paulis: first.supports, + means, + stds, + n_samples, + } +} + +impl RateUncertainty { + /// Look up mean rate for a given Pauli; returns 0 if not in support. + pub fn mean(&self, p: &crate::PauliString) -> f64 { + self.paulis + .iter() + .zip(&self.means) + .find(|(s, _)| *s == p) + .map(|(_, v)| *v) + .unwrap_or(0.0) + } + + /// Look up standard deviation for a given Pauli; returns 0 if not in support. + pub fn std(&self, p: &crate::PauliString) -> f64 { + self.paulis + .iter() + .zip(&self.stds) + .find(|(s, _)| *s == p) + .map(|(_, v)| *v) + .unwrap_or(0.0) + } +} + #[cfg(test)] mod tests { use super::*; diff --git a/exp/pecos-lindblad/tests/uncertainty_propagation.rs b/exp/pecos-lindblad/tests/uncertainty_propagation.rs new file mode 100644 index 000000000..b879abda3 --- /dev/null +++ b/exp/pecos-lindblad/tests/uncertainty_propagation.rs @@ -0,0 +1,123 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Monte-Carlo uncertainty propagation tests. For 1Q identity + AD+PD the +//! rates are exactly `lambda_x = lambda_y = beta_down tau/4` and +//! `lambda_z = beta_phi tau/2`, so uncertainty propagation is analytic: +//! +//! d lambda_x / d T_1 = -tau / (4 T_1^2) +//! d lambda_z / d T_1 = -tau / (2 * 2 T_1^2) = -tau / (4 T_1^2) (from 1/(2T_1)) +//! d lambda_z / d T_2 = -tau / (2 T_2^2) +//! +//! For small Gaussian jitter, first-order MC std should match these +//! derivatives times the input sigma, to within Monte-Carlo error. + +use rand::rngs::StdRng; +use rand::{RngExt, SeedableRng}; + +use pecos_lindblad::noise_models::{ad_pd_1q, propagate_uncertainty}; +use pecos_lindblad::{synthesize_identity_1q, Gate, Pauli1, PauliString}; + +fn gaussian(rng: &mut StdRng, mean: f64, sigma: f64) -> f64 { + // Box-Muller. + let u1: f64 = rng.random_range(1e-15f64..1.0f64); + let u2: f64 = rng.random_range(0.0f64..1.0f64); + mean + sigma * f64::sqrt(-2.0 * f64::ln(u1)) * f64::cos(2.0 * std::f64::consts::PI * u2) +} + +#[test] +fn uncertainty_propagation_gives_expected_std_scale() { + let t1_mean = 100.0; + let t2_mean = 80.0; + let t1_sigma = 5.0; // 5% relative + let t2_sigma = 4.0; // 5% relative + let tau_g = 1.0; + let n_samples = 2000; + + let mut rng = StdRng::seed_from_u64(42); + let unc = propagate_uncertainty(n_samples, |_k| { + let t1 = gaussian(&mut rng, t1_mean, t1_sigma).max(t2_mean / 2.0 + 1e-3); + let t2 = gaussian(&mut rng, t2_mean, t2_sigma).min(2.0 * t1).max(1e-3); + let noise = ad_pd_1q(t1, t2); + let gate = Gate::identity(1, noise, tau_g); + synthesize_identity_1q(&gate) + }); + + // Sanity: means should be close to central-parameter prediction. + let beta_down = 1.0 / t1_mean; + let beta_phi = 1.0 / t2_mean - 1.0 / (2.0 * t1_mean); + let expected_mean_x = beta_down * tau_g / 4.0; + let expected_mean_z = beta_phi * tau_g / 2.0; + + let got_mean_x = unc.mean(&PauliString::single(Pauli1::X)); + let got_mean_z = unc.mean(&PauliString::single(Pauli1::Z)); + // Monte-Carlo sample-mean error ~ std / sqrt(N); allow 5 sigma. + let got_std_x = unc.std(&PauliString::single(Pauli1::X)); + let got_std_z = unc.std(&PauliString::single(Pauli1::Z)); + let mean_err_tol_x = 5.0 * got_std_x / (n_samples as f64).sqrt(); + let mean_err_tol_z = 5.0 * got_std_z / (n_samples as f64).sqrt(); + // Add small bias tolerance for the boundary clamping above. + assert!( + (got_mean_x - expected_mean_x).abs() < 5.0 * mean_err_tol_x + 0.05 * expected_mean_x, + "mean_x: got {}, expected {}, diff {}", + got_mean_x, + expected_mean_x, + (got_mean_x - expected_mean_x).abs(), + ); + assert!( + (got_mean_z - expected_mean_z).abs() < 5.0 * mean_err_tol_z + 0.05 * expected_mean_z, + "mean_z: got {}, expected {}, diff {}", + got_mean_z, + expected_mean_z, + (got_mean_z - expected_mean_z).abs(), + ); + + // Std should be non-trivial (not collapsed to zero) and in the right ballpark + // via first-order propagation: sigma_lambda_x ~ tau/(4 T_1^2) * sigma_T1. + let predicted_sigma_x = tau_g / (4.0 * t1_mean.powi(2)) * t1_sigma; + assert!( + got_std_x > 0.3 * predicted_sigma_x && got_std_x < 3.0 * predicted_sigma_x, + "sigma_x: got {}, predicted (1st-order) {}, out of factor-3 range", + got_std_x, + predicted_sigma_x, + ); +} + +#[test] +fn uncertainty_std_scales_linearly_with_input_sigma() { + // Double the input sigma -> output sigma should roughly double + // (first-order Taylor expansion). + let t1_mean = 100.0; + let t2_mean = 80.0; + let tau_g = 1.0; + + let run = |sigma_t1: f64, seed: u64| -> f64 { + let mut rng = StdRng::seed_from_u64(seed); + let unc = propagate_uncertainty(1000, |_k| { + let t1 = gaussian(&mut rng, t1_mean, sigma_t1).max(t2_mean / 2.0 + 1e-3); + let noise = ad_pd_1q(t1, t2_mean); + let gate = Gate::identity(1, noise, tau_g); + synthesize_identity_1q(&gate) + }); + unc.std(&PauliString::single(Pauli1::X)) + }; + + let s1 = run(2.0, 11); + let s2 = run(4.0, 11); + // Ratio should be ~2, allow 25% slack for MC noise. + let ratio = s2 / s1; + assert!( + (ratio - 2.0).abs() < 0.5, + "std did not scale linearly: s1={}, s2={}, ratio={}", + s1, s2, ratio + ); +} From 6eb56eb74a0f9e41440e03a17c9683358d2c8d87 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 12:21:12 -0600 Subject: [PATCH 033/125] Limit fix F4: general time-sliced superop synthesis for mixed noise + H_g != 0 --- exp/pecos-lindblad/src/lib.rs | 3 +- exp/pecos-lindblad/src/synthesis.rs | 87 ++++++++++++ .../tests/synthesize_superop_full.rs | 127 ++++++++++++++++++ 3 files changed, 216 insertions(+), 1 deletion(-) create mode 100644 exp/pecos-lindblad/tests/synthesize_superop_full.rs diff --git a/exp/pecos-lindblad/src/lib.rs b/exp/pecos-lindblad/src/lib.rs index fb83d8ddd..48874ada9 100644 --- a/exp/pecos-lindblad/src/lib.rs +++ b/exp/pecos-lindblad/src/lib.rs @@ -86,5 +86,6 @@ pub use lindbladian::Lindbladian; pub use pauli_lindblad::PauliLindbladModel; pub use synthesis::{ synthesize_exact_unitary, synthesize_identity_1q, synthesize_numerical, - synthesize_numerical_1q, synthesize_superop_identity, DEFAULT_N_STEPS, + synthesize_numerical_1q, synthesize_superop, synthesize_superop_identity, + DEFAULT_N_SLICES, DEFAULT_N_STEPS, }; diff --git a/exp/pecos-lindblad/src/synthesis.rs b/exp/pecos-lindblad/src/synthesis.rs index 55adda857..dd439db60 100644 --- a/exp/pecos-lindblad/src/synthesis.rs +++ b/exp/pecos-lindblad/src/synthesis.rs @@ -65,6 +65,93 @@ pub fn synthesize_numerical_1q(gate: &Gate, n_steps: usize) -> PauliLindbladMode synthesize_numerical(gate, n_steps) } +/// Default number of time slices for `synthesize_superop`. Midpoint-rule +/// propagator per slice is second-order accurate; `N=128` gives ~`1e-10` +/// precision for single-oscillation gates. +pub const DEFAULT_N_SLICES: usize = 128; + +/// **General** synthesis for any gate with any combination of coherent +/// and dissipative noise via time-slicing of the interaction-frame +/// Lindblad superoperator. +/// +/// For each midpoint `t_k`, builds `L_I(t_k) = U_g^dag(t_k) L_noise +/// U_g(t_k)`, exponentiates to get a per-slice propagator +/// `exp(L_I(t_k) * dt)` and multiplies them left-to-right to form +/// `U_total`. Applies to each `vec(P_b)`, extracts Pauli fidelity, inverts +/// via Walsh-Hadamard. +/// +/// This is the only path that handles **gates with `H_g != 0` AND +/// simultaneous coherent + dissipative noise** -- the general case that +/// `synthesize_numerical` (dissipative leading-order only) and +/// `synthesize_exact_unitary` (coherent, asserts no c_ops) don't cover. +/// +/// Cost: `n_slices` per-slice superoperator builds + exps at size +/// `d^2 x d^2`. For 2Q gates `d^2=16`, comfortably sub-second at +/// `n_slices=128`. +pub fn synthesize_superop(gate: &Gate, n_slices: usize) -> PauliLindbladModel { + assert!(n_slices >= 1, "n_slices must be >= 1"); + let n = gate.num_qubits; + let d = 1usize << n; + let d2 = d * d; + let tau = gate.tau_g; + let dt = tau / n_slices as f64; + + let h_g = &gate.ideal.hamiltonian; + let h_delta = &gate.noise.hamiltonian; + + // U_total = prod_k exp(L_I(t_k) * dt), built left-to-right (newest leftmost). + let mut u_total = matrix::identity(d2); + for k in 0..n_slices { + let t_mid = (k as f64 + 0.5) * dt; + let u_g = matrix::exp_minus_i_h_t(h_g, d, t_mid); + let u_g_dag = matrix::dag(&u_g, d); + + // Transform noise operators to the interaction frame at t_mid. + let h_i = matrix::matmul(&matrix::matmul(&u_g_dag, h_delta, d), &u_g, d); + let collapse_i: Vec<(Matrix, f64)> = gate + .noise + .collapse + .iter() + .map(|(c, g)| { + ( + matrix::matmul(&matrix::matmul(&u_g_dag, c, d), &u_g, d), + *g, + ) + }) + .collect(); + + // L_I(t_mid) superop. + let lind_i = Lindbladian::new(d, h_i, collapse_i); + let l_super = lind_i.superoperator(); + + // Per-slice propagator and accumulate. + let u_slice = matrix::expm(&matrix::scale(&l_super, Complex64::new(dt, 0.0)), d2); + u_total = matrix::matmul(&u_slice, &u_total, d2); + } + + // Apply to each Pauli, extract fidelities, invert. + let paulis = PauliString::enumerate_nonidentity(n); + let alphas: Vec = paulis + .iter() + .map(|p| { + let p_mat = matrix::pauli_string_mat(p); + let vec_p = matrix::vec_of(&p_mat, d); + let vec_applied = matrix::matvec(&u_total, &vec_p, d2); + let applied = matrix::unvec(&vec_applied, d); + let inner = matrix::trace(&matrix::matmul(&p_mat, &applied, d), d); + let f_b = inner.re / d as f64; + assert!( + f_b > 0.1, + "Pauli fidelity {} too low for {:?}; noise outside weak regime", + f_b, + p, + ); + -f_b.ln() + }) + .collect(); + model_from_alphas_walsh(paulis, alphas, n) +} + /// Synthesize a Pauli-Lindblad model from **mixed coherent + dissipative /// noise** on a time-independent ideal Hamiltonian (currently: identity /// gate, `H_g = 0`) via the full Lindblad superoperator path. diff --git a/exp/pecos-lindblad/tests/synthesize_superop_full.rs b/exp/pecos-lindblad/tests/synthesize_superop_full.rs new file mode 100644 index 000000000..6ac831d61 --- /dev/null +++ b/exp/pecos-lindblad/tests/synthesize_superop_full.rs @@ -0,0 +1,127 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Tests for `synthesize_superop` -- the fully-general time-sliced path +//! that handles `H_g != 0` AND simultaneous coherent + dissipative noise. +//! +//! Three validation modes: +//! 1. Matches `synthesize_numerical` on pure dissipative inputs (CX+AD+PD). +//! 2. Matches `synthesize_exact_unitary` on pure coherent inputs (CX+phase). +//! 3. NEW: handles mixed input that neither of the above covers +//! (CX_theta + AD+PD + coherent ZZ phase, all at once). + +use approx::assert_abs_diff_eq; +use num_complex::Complex64; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::noise_models::{ad_pd_2q, coherent_phase_2q}; +use pecos_lindblad::{ + synthesize_exact_unitary, synthesize_numerical, synthesize_superop, Gate, Lindbladian, Pauli1, + PauliString, DEFAULT_N_SLICES, DEFAULT_N_STEPS, +}; + +#[test] +fn superop_matches_synthesize_numerical_cx_ad_pd() { + // Weak dissipative noise on CX_theta: superop (all orders) and + // synthesize_numerical (leading order) should agree to high precision. + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + let noise = ad_pd_2q(1e5, 1e5, 8e4, 8e4); // very weak + let gate = Gate::cx_theta(omega, theta, noise); + + let simpson = synthesize_numerical(&gate, DEFAULT_N_STEPS); + let superop = synthesize_superop(&gate, DEFAULT_N_SLICES); + + for ps in PauliString::enumerate_nonidentity(2) { + // At this noise level (~1e-5), O(beta^2) corrections are ~1e-10 + // and negligible. Expect agreement to ~1e-9. + assert_abs_diff_eq!(simpson.rate(&ps), superop.rate(&ps), epsilon = 1e-9); + } +} + +#[test] +fn superop_matches_synthesize_exact_unitary_cx_coherent() { + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + let noise = coherent_phase_2q(1e-5, 2e-5, 5e-6); + let gate = Gate::cx_theta(omega, theta, noise); + + let exact = synthesize_exact_unitary(&gate); + let superop = synthesize_superop(&gate, DEFAULT_N_SLICES); + + for ps in PauliString::enumerate_nonidentity(2) { + assert_abs_diff_eq!(exact.rate(&ps), superop.rate(&ps), epsilon = 1e-10); + } +} + +#[test] +fn superop_handles_cx_mixed_ad_pd_plus_coherent_zz() { + // THE new capability: CX_theta with simultaneous AD+PD dissipators + // AND coherent ZZ phase noise. No other synthesis path can do this: + // - synthesize_numerical: dissipative leading-order, loses coherent + // quadratic contribution. + // - synthesize_exact_unitary: asserts no c_ops, refuses mixed input. + // - synthesize_superop_identity: requires H_g = 0. + let d = 4; + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + let t1 = 1e5; // very weak AD + let t2 = 8e4; // weak PD + let delta_zz = 1e-4; // weak coherent ZZ + + let i2 = matrix::identity(2); + let sm = matrix::sigma_minus(); + let z = matrix::pauli_1q(Pauli1::Z); + let sm_l = matrix::kron(&sm, &i2, 2, 2); + let sm_r = matrix::kron(&i2, &sm, 2, 2); + let z_l = matrix::kron(&z, &i2, 2, 2); + let z_r = matrix::kron(&i2, &z, 2, 2); + let zz = matrix::kron(&z, &z, 2, 2); + + let beta_down = 1.0 / t1; + let beta_phi = 1.0 / t2 - 1.0 / (2.0 * t1); + let h_delta = matrix::scale(&zz, Complex64::new(delta_zz / 2.0, 0.0)); + let collapse: Vec<(Matrix, f64)> = vec![ + (sm_l, beta_down), + (sm_r, beta_down), + (z_l, beta_phi / 2.0), + (z_r, beta_phi / 2.0), + ]; + let mixed = Lindbladian::new(d, h_delta, collapse); + let mixed_gate = Gate::cx_theta(omega, theta, mixed); + + // Also build pure-dissipative and pure-coherent variants for + // superposition comparison. + let pure_diss = ad_pd_2q(t1, t1, t2, t2); + let diss_gate = Gate::cx_theta(omega, theta, pure_diss); + let pure_coh = coherent_phase_2q(0.0, 0.0, delta_zz); + let coh_gate = Gate::cx_theta(omega, theta, pure_coh); + + let pl_mixed = synthesize_superop(&mixed_gate, DEFAULT_N_SLICES); + let pl_diss = synthesize_superop(&diss_gate, DEFAULT_N_SLICES); + let pl_coh = synthesize_superop(&coh_gate, DEFAULT_N_SLICES); + + // At weak coupling, the mixed rates should equal the superposition of + // the two individual-noise rates (cross-terms are second-order small). + for ps in PauliString::enumerate_nonidentity(2) { + let expected = pl_diss.rate(&ps) + pl_coh.rate(&ps); + let got = pl_mixed.rate(&ps); + // Cross-term O(beta * delta * tau^2) ~ 1e-5 * 1e-4 * 1 = 1e-9. + // Use tolerance slightly above that to account for MC/numerical noise. + assert_abs_diff_eq!(got, expected, epsilon = 1e-8); + } + + // Additional sanity: mixed has non-trivial rates from both sources. + let rate_mixed = |s: &str| pl_mixed.rate(&PauliString::from_str(s).unwrap()); + assert!(rate_mixed("IX") > 1e-8, "dissipative contribution should be present"); + assert!(rate_mixed("ZZ") > 1e-10, "coherent ZZ contribution should be present"); +} From cb958eef9a1353cc18cb5873d521feb66d3561c2 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 12:27:50 -0600 Subject: [PATCH 034/125] Limit fix F5: inverse fit (analytic 1Q recovery) + compose_independent --- exp/pecos-lindblad/src/noise_models.rs | 49 ++++++++ exp/pecos-lindblad/src/pauli_lindblad.rs | 25 ++++ exp/pecos-lindblad/tests/inverse_fit.rs | 146 +++++++++++++++++++++++ 3 files changed, 220 insertions(+) create mode 100644 exp/pecos-lindblad/tests/inverse_fit.rs diff --git a/exp/pecos-lindblad/src/noise_models.rs b/exp/pecos-lindblad/src/noise_models.rs index 451865f5c..8c051567b 100644 --- a/exp/pecos-lindblad/src/noise_models.rs +++ b/exp/pecos-lindblad/src/noise_models.rs @@ -110,6 +110,55 @@ pub fn coherent_phase_2q(delta_iz: f64, delta_zi: f64, delta_zz: f64) -> Lindbla Lindbladian::new(d, h_delta, Vec::new()) } +/// Analytic back-solve: given measured PL rates from a 1Q identity gate +/// with AD+PD noise, recover `(T_1, T_2)`. +/// +/// Inverse of [`ad_pd_1q`] applied to [`crate::synthesize_identity_1q`] +/// using the paper's closed form (line 812): +/// +/// ```text +/// lambda_x = lambda_y = beta_down * tau_g / 4 => T_1 = tau_g / (4 lambda_x) +/// lambda_z = beta_phi * tau_g / 2 => T_phi = tau_g / (2 lambda_z) +/// 1/T_2 = 1/(2 T_1) + 1/T_phi => T_2 = 1 / (1/(2 T_1) + 1/T_phi) +/// ``` +/// +/// Returns `None` if rates are inconsistent (e.g. negative or would imply +/// `T_2 > 2 T_1`). Averages `lambda_x` and `lambda_y` for robustness +/// against small measurement noise. +pub fn recover_t1_t2_from_identity_1q( + model: &crate::PauliLindbladModel, + tau_g: f64, +) -> Option<(f64, f64)> { + use crate::{Pauli1, PauliString}; + if tau_g <= 0.0 { + return None; + } + let lam_x = model.rate(&PauliString::single(Pauli1::X)); + let lam_y = model.rate(&PauliString::single(Pauli1::Y)); + let lam_z = model.rate(&PauliString::single(Pauli1::Z)); + // AD gives equal lambda_x and lambda_y; average for noise robustness. + let lam_avg_xy = 0.5 * (lam_x + lam_y); + if lam_avg_xy <= 0.0 || lam_z < 0.0 { + return None; + } + let t1 = tau_g / (4.0 * lam_avg_xy); + if t1 <= 0.0 { + return None; + } + // lambda_z = 0 is allowed (pure-T1 limit => T_2 = 2 T_1). + let t2 = if lam_z < 1e-30 { + 2.0 * t1 + } else { + let t_phi = tau_g / (2.0 * lam_z); + let inv_t2 = 1.0 / (2.0 * t1) + 1.0 / t_phi; + if inv_t2 <= 0.0 { + return None; + } + 1.0 / inv_t2 + }; + Some((t1, t2)) +} + /// Per-Pauli mean + standard-deviation statistics from a Monte-Carlo /// uncertainty propagation. #[derive(Clone, Debug, Default)] diff --git a/exp/pecos-lindblad/src/pauli_lindblad.rs b/exp/pecos-lindblad/src/pauli_lindblad.rs index b16fa227d..d9829bf3b 100644 --- a/exp/pecos-lindblad/src/pauli_lindblad.rs +++ b/exp/pecos-lindblad/src/pauli_lindblad.rs @@ -97,6 +97,31 @@ impl PauliLindbladModel { self.diff(other).into_iter().next().map(|(p, _, _, r)| (p, r)) } + /// Leading-order composition of two independent noise sources: rates + /// add per Pauli. Exact for small rates where `(1 - (1-p_A)(1-p_B)) ≈ + /// p_A + p_B`. For larger rates, prefer [`synthesize_superop`] on the + /// combined physical Lindbladian directly (all-orders). + /// + /// Use case: combine a predicted physical-model PL with an + /// experimentally-observed residual-noise PL to get an effective + /// model for circuit-level noise. + pub fn compose_independent(&self, other: &Self) -> Self { + use std::collections::HashMap; + let mut combined: HashMap = HashMap::new(); + for (p, r) in self.supports.iter().zip(&self.rates) { + combined.insert(p.clone(), *r); + } + for (p, r) in other.supports.iter().zip(&other.rates) { + *combined.entry(p.clone()).or_insert(0.0) += *r; + } + let mut entries: Vec<_> = combined.into_iter().collect(); + entries.sort_by(|(a, _), (b, _)| { + a.0.iter().map(|p| *p as u8).cmp(b.0.iter().map(|p| *p as u8)) + }); + let (supports, rates): (Vec<_>, Vec<_>) = entries.into_iter().unzip(); + Self::new(supports, rates) + } + /// Aggregate absolute residual by Pauli weight. Returns `weight -> sum /// of |residual|`. Useful for diagnosing which weight class of physics /// is missing from the model (e.g. weight-2 residual large => diff --git a/exp/pecos-lindblad/tests/inverse_fit.rs b/exp/pecos-lindblad/tests/inverse_fit.rs new file mode 100644 index 000000000..3038d59a3 --- /dev/null +++ b/exp/pecos-lindblad/tests/inverse_fit.rs @@ -0,0 +1,146 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Inverse fit / parameter recovery tests. Closes the "validation loop": +//! forward synthesis produces rates; inverse recovery back-solves physical +//! parameters from rates. At the 1Q identity level, the recovery is +//! analytic and must be a bit-exact round-trip of +//! [`noise_models::ad_pd_1q`] -> [`synthesize_identity_1q`]. + +use approx::assert_abs_diff_eq; + +use pecos_lindblad::noise_models::{ad_pd_1q, recover_t1_t2_from_identity_1q}; +use pecos_lindblad::{ + synthesize_identity_1q, Gate, Pauli1, PauliLindbladModel, PauliString, +}; + +fn synth_1q(t1: f64, t2: f64, tau_g: f64) -> PauliLindbladModel { + synthesize_identity_1q(&Gate::identity(1, ad_pd_1q(t1, t2), tau_g)) +} + +#[test] +fn round_trip_recovery_1q_ad_pd() { + for (t1, t2, tau) in [ + (100.0, 80.0, 1.0), + (300.0, 200.0, 0.5), + (50.0, 50.0, 2.0), // T_2 = T_1 case + ] { + let pl = synth_1q(t1, t2, tau); + let (t1_rec, t2_rec) = recover_t1_t2_from_identity_1q(&pl, tau).unwrap(); + assert_abs_diff_eq!(t1_rec, t1, epsilon = 1e-10); + assert_abs_diff_eq!(t2_rec, t2, epsilon = 1e-10); + } +} + +#[test] +fn recovery_handles_t2_equals_2_t1_limit() { + // Pure-T1 limit (no dephasing): T_2 = 2 T_1, so lambda_z = 0 exactly. + let t1 = 150.0; + let t2 = 2.0 * t1; + let tau = 1.0; + let pl = synth_1q(t1, t2, tau); + let (t1_rec, t2_rec) = recover_t1_t2_from_identity_1q(&pl, tau).unwrap(); + assert_abs_diff_eq!(t1_rec, t1, epsilon = 1e-10); + assert_abs_diff_eq!(t2_rec, t2, epsilon = 1e-10); +} + +#[test] +fn recovery_returns_none_on_inconsistent_rates() { + // lambda_x=0 => cannot determine T_1. + let pl = PauliLindbladModel::new( + vec![ + PauliString::single(Pauli1::X), + PauliString::single(Pauli1::Z), + ], + vec![0.0, 0.01], + ); + assert!(recover_t1_t2_from_identity_1q(&pl, 1.0).is_none()); +} + +#[test] +fn recovery_returns_none_on_zero_tau() { + let pl = synth_1q(100.0, 80.0, 1.0); + assert!(recover_t1_t2_from_identity_1q(&pl, 0.0).is_none()); +} + +#[test] +fn compose_independent_sums_rates() { + let a = PauliLindbladModel::new( + vec![ + PauliString::from_str("IX").unwrap(), + PauliString::from_str("ZZ").unwrap(), + ], + vec![0.001, 0.005], + ); + let b = PauliLindbladModel::new( + vec![ + PauliString::from_str("IX").unwrap(), + PauliString::from_str("XI").unwrap(), + ], + vec![0.002, 0.003], + ); + let ab = a.compose_independent(&b); + // Expected support: IX (merged), XI, ZZ. Rates: IX=0.003, XI=0.003, ZZ=0.005. + assert_abs_diff_eq!( + ab.rate(&PauliString::from_str("IX").unwrap()), + 0.003, + epsilon = 1e-14 + ); + assert_abs_diff_eq!( + ab.rate(&PauliString::from_str("XI").unwrap()), + 0.003, + epsilon = 1e-14 + ); + assert_abs_diff_eq!( + ab.rate(&PauliString::from_str("ZZ").unwrap()), + 0.005, + epsilon = 1e-14 + ); + assert_eq!(ab.supports.len(), 3); +} + +#[test] +fn compose_commutes() { + let a = PauliLindbladModel::new( + vec![PauliString::single(Pauli1::X)], + vec![0.01], + ); + let b = PauliLindbladModel::new( + vec![PauliString::single(Pauli1::Z)], + vec![0.02], + ); + let ab = a.compose_independent(&b); + let ba = b.compose_independent(&a); + for p in [Pauli1::X, Pauli1::Y, Pauli1::Z] { + let k = PauliString::single(p); + assert_abs_diff_eq!(ab.rate(&k), ba.rate(&k), epsilon = 1e-14); + } +} + +#[test] +fn round_trip_validation_workflow() { + // End-to-end: predict rates from (T1, T2), then recover T1/T2 from + // those rates, verify the loop closes. + let t1_nominal = 250.0; + let t2_nominal = 180.0; + let tau = 0.5; + + // 1. Forward: physics -> rates. + let predicted = synth_1q(t1_nominal, t2_nominal, tau); + + // 2. Inverse: rates -> physics. + let (t1_back, t2_back) = recover_t1_t2_from_identity_1q(&predicted, tau).unwrap(); + + // 3. Closure. + assert_abs_diff_eq!(t1_back, t1_nominal, epsilon = 1e-10); + assert_abs_diff_eq!(t2_back, t2_nominal, epsilon = 1e-10); +} From 28be80a2b9fa98ce8f09051feff9862b9cc769c2 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 12:38:59 -0600 Subject: [PATCH 035/125] Limit fix F6: 2Q CZ_theta inverse fit with model-mismatch residual --- exp/pecos-lindblad/src/noise_models.rs | 84 +++++++++++++ exp/pecos-lindblad/tests/inverse_fit_2q.rs | 130 +++++++++++++++++++++ 2 files changed, 214 insertions(+) create mode 100644 exp/pecos-lindblad/tests/inverse_fit_2q.rs diff --git a/exp/pecos-lindblad/src/noise_models.rs b/exp/pecos-lindblad/src/noise_models.rs index 8c051567b..5b52f0513 100644 --- a/exp/pecos-lindblad/src/noise_models.rs +++ b/exp/pecos-lindblad/src/noise_models.rs @@ -159,6 +159,90 @@ pub fn recover_t1_t2_from_identity_1q( Some((t1, t2)) } +/// Recovered 2-qubit coherence-time parameters for the (left, right) +/// qubits of a 2Q gate. +#[derive(Clone, Copy, Debug, PartialEq)] +pub struct RecoveredParams2Q { + pub t1_l: f64, + pub t2_l: f64, + pub t1_r: f64, + pub t2_r: f64, +} + +/// Analytic 2Q recovery: given a measured `CZ_theta + AD+PD` PL model, +/// back-solve `(T_1, T_2)` on each qubit. +/// +/// Uses paper arXiv:2502.03462 eqs. 896-906: +/// +/// ```text +/// lambda_zi = (theta/2) * (beta_phi_l / omega_cz) +/// lambda_iz = (theta/2) * (beta_phi_r / omega_cz) +/// lambda_xi = lambda_yi = (2*theta + sin(2*theta))/16 * beta_down_l / omega_cz +/// lambda_ix = lambda_iy = (2*theta + sin(2*theta))/16 * beta_down_r / omega_cz +/// ``` +/// +/// Averages the degenerate-in-paper pairs (`lambda_xi` ≈ `lambda_yi`) +/// for robustness against noisy measurements. Returns `None` if rates +/// are inconsistent (e.g. negative) or would imply `T_2 > 2 T_1`. +pub fn recover_ad_pd_2q_from_cz_theta( + model: &crate::PauliLindbladModel, + omega_cz: f64, + theta: f64, +) -> Option { + use crate::PauliString; + if omega_cz <= 0.0 || theta <= 0.0 { + return None; + } + let r = |s: &str| model.rate(&PauliString::from_str(s).unwrap()); + let factor_weight1_amp = (2.0 * theta + (2.0 * theta).sin()) / 16.0; + + // Amplitude damping: average the two equal rates (paper's 2-fold degeneracy). + let beta_down_r = 0.5 * (r("IX") + r("IY")) * omega_cz / factor_weight1_amp; + let beta_down_l = 0.5 * (r("XI") + r("YI")) * omega_cz / factor_weight1_amp; + + // Dephasing: single-rate back-solve. + let beta_phi_r = r("IZ") * 2.0 * omega_cz / theta; + let beta_phi_l = r("ZI") * 2.0 * omega_cz / theta; + + if beta_down_l < 0.0 || beta_down_r < 0.0 || beta_phi_l < 0.0 || beta_phi_r < 0.0 { + return None; + } + if beta_down_l < 1e-300 || beta_down_r < 1e-300 { + return None; + } + + let t1_l = 1.0 / beta_down_l; + let t1_r = 1.0 / beta_down_r; + // 1/T_2 = 1/(2 T_1) + 1/T_phi and 1/T_phi = beta_phi. + let inv_t2_l = 1.0 / (2.0 * t1_l) + beta_phi_l; + let inv_t2_r = 1.0 / (2.0 * t1_r) + beta_phi_r; + if inv_t2_l <= 0.0 || inv_t2_r <= 0.0 { + return None; + } + Some(RecoveredParams2Q { + t1_l, + t2_l: 1.0 / inv_t2_l, + t1_r, + t2_r: 1.0 / inv_t2_r, + }) +} + +/// Consistency residual for a `CZ_theta + AD+PD` recovery: for the +/// recovered parameters, compute the L2 residual between observed +/// degenerate-pair rates (`lambda_xi` vs `lambda_yi`, etc.). Large +/// residuals flag model mismatch (noise source beyond AD+PD). +pub fn cz_recovery_residual(model: &crate::PauliLindbladModel) -> f64 { + use crate::PauliString; + let r = |s: &str| model.rate(&PauliString::from_str(s).unwrap()); + let pairs = [ + (r("IX"), r("IY")), + (r("XI"), r("YI")), + (r("ZX"), r("ZY")), + (r("XZ"), r("YZ")), + ]; + pairs.iter().map(|(a, b)| (a - b).powi(2)).sum::().sqrt() +} + /// Per-Pauli mean + standard-deviation statistics from a Monte-Carlo /// uncertainty propagation. #[derive(Clone, Debug, Default)] diff --git a/exp/pecos-lindblad/tests/inverse_fit_2q.rs b/exp/pecos-lindblad/tests/inverse_fit_2q.rs new file mode 100644 index 000000000..021b0e0cf --- /dev/null +++ b/exp/pecos-lindblad/tests/inverse_fit_2q.rs @@ -0,0 +1,130 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! 2-qubit inverse-fit tests for `CZ_theta + AD+PD`. Round-trip: +//! (T_1, T_2)_{l,r} -> synthesize -> PL rates -> recover -> (T_1, T_2)_{l,r}. +//! Must be bit-close on clean (noiseless) synthetic data. + +use approx::assert_abs_diff_eq; + +use pecos_lindblad::noise_models::{ + ad_pd_2q, cz_recovery_residual, recover_ad_pd_2q_from_cz_theta, +}; +use pecos_lindblad::{ + synthesize_numerical, Gate, PauliLindbladModel, PauliString, DEFAULT_N_STEPS, +}; + +fn synth_cz(t1_l: f64, t1_r: f64, t2_l: f64, t2_r: f64, omega: f64, theta: f64) -> PauliLindbladModel { + let noise = ad_pd_2q(t1_l, t1_r, t2_l, t2_r); + let gate = Gate::cz_theta(omega, theta, noise); + synthesize_numerical(&gate, DEFAULT_N_STEPS) +} + +#[test] +fn round_trip_2q_asymmetric_params() { + // Four independent parameters; recovery should find all four. + let t1_l = 120.0; + let t1_r = 80.0; + let t2_l = 90.0; + let t2_r = 60.0; + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + + let pl = synth_cz(t1_l, t1_r, t2_l, t2_r, omega, theta); + let rec = recover_ad_pd_2q_from_cz_theta(&pl, omega, theta).unwrap(); + + assert_abs_diff_eq!(rec.t1_l, t1_l, epsilon = 1e-10); + assert_abs_diff_eq!(rec.t1_r, t1_r, epsilon = 1e-10); + assert_abs_diff_eq!(rec.t2_l, t2_l, epsilon = 1e-10); + assert_abs_diff_eq!(rec.t2_r, t2_r, epsilon = 1e-10); +} + +#[test] +fn round_trip_2q_at_pi_over_3() { + let pl = synth_cz(200.0, 200.0, 150.0, 150.0, 1.5, std::f64::consts::FRAC_PI_3); + let rec = recover_ad_pd_2q_from_cz_theta(&pl, 1.5, std::f64::consts::FRAC_PI_3).unwrap(); + assert_abs_diff_eq!(rec.t1_l, 200.0, epsilon = 1e-10); + assert_abs_diff_eq!(rec.t1_r, 200.0, epsilon = 1e-10); + assert_abs_diff_eq!(rec.t2_l, 150.0, epsilon = 1e-10); + assert_abs_diff_eq!(rec.t2_r, 150.0, epsilon = 1e-10); +} + +#[test] +fn recovery_residual_small_for_pure_ad_pd() { + // On clean AD+PD synthesis, the degenerate rate pairs should + // coincide to machine precision -> residual ~ 0. + let pl = synth_cz(100.0, 80.0, 80.0, 60.0, 1.0, std::f64::consts::FRAC_PI_4); + let residual = cz_recovery_residual(&pl); + assert!(residual < 1e-10, "residual for clean AD+PD should be near zero: {}", residual); +} + +#[test] +fn recovery_residual_nonzero_under_model_mismatch() { + // Build a model where the degenerate pairs explicitly *differ* -- + // simulating measured rates that don't fit the pure-AD+PD form. + let supports: Vec<_> = ["IX", "IY", "XI", "YI"] + .iter() + .map(|s| PauliString::from_str(s).unwrap()) + .collect(); + // IX, IY differ by 20% (not allowed under pure AD+PD for CZ). + let rates = vec![0.003, 0.0036, 0.002, 0.002]; + let pl = PauliLindbladModel::new(supports, rates); + let residual = cz_recovery_residual(&pl); + assert!( + residual > 1e-4, + "expected residual to flag the mismatch, got {}", + residual + ); +} + +#[test] +fn recovery_returns_none_on_negative_rates() { + let supports = vec![ + PauliString::from_str("IX").unwrap(), + PauliString::from_str("IY").unwrap(), + PauliString::from_str("XI").unwrap(), + PauliString::from_str("YI").unwrap(), + PauliString::from_str("IZ").unwrap(), + PauliString::from_str("ZI").unwrap(), + ]; + // lambda_ix is zero -> recovery can't infer beta_down_r. + let rates = vec![0.0, 0.0, 0.001, 0.001, 0.002, 0.002]; + let pl = PauliLindbladModel::new(supports, rates); + assert!(recover_ad_pd_2q_from_cz_theta(&pl, 1.0, std::f64::consts::FRAC_PI_4).is_none()); +} + +#[test] +fn round_trip_2q_validation_workflow() { + // End-to-end validation story: 4 device params -> 15 PL rates -> + // recover 4 params -> compare. + let t1_l = 250.0; + let t2_l = 180.0; + let t1_r = 300.0; + let t2_r = 220.0; + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + + // 1. Forward: physics -> rates. + let pl = synth_cz(t1_l, t1_r, t2_l, t2_r, omega, theta); + + // 2. Consistency check: on clean data the 2-fold pair residual = 0. + assert!(cz_recovery_residual(&pl) < 1e-10); + + // 3. Inverse. + let rec = recover_ad_pd_2q_from_cz_theta(&pl, omega, theta).unwrap(); + + // 4. Closure. + assert_abs_diff_eq!(rec.t1_l, t1_l, epsilon = 1e-10); + assert_abs_diff_eq!(rec.t2_l, t2_l, epsilon = 1e-10); + assert_abs_diff_eq!(rec.t1_r, t1_r, epsilon = 1e-10); + assert_abs_diff_eq!(rec.t2_r, t2_r, epsilon = 1e-10); +} From 6f5bfa57f6bd2efb4d07f83318ee76b05cad2500 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 12:41:13 -0600 Subject: [PATCH 036/125] Limit fix F7: 2Q CX_theta inverse fit with sin(2 theta) decoupling --- exp/pecos-lindblad/src/noise_models.rs | 63 +++++++++++ exp/pecos-lindblad/tests/inverse_fit_2q_cx.rs | 103 ++++++++++++++++++ 2 files changed, 166 insertions(+) create mode 100644 exp/pecos-lindblad/tests/inverse_fit_2q_cx.rs diff --git a/exp/pecos-lindblad/src/noise_models.rs b/exp/pecos-lindblad/src/noise_models.rs index 5b52f0513..3794c1d63 100644 --- a/exp/pecos-lindblad/src/noise_models.rs +++ b/exp/pecos-lindblad/src/noise_models.rs @@ -227,6 +227,69 @@ pub fn recover_ad_pd_2q_from_cz_theta( }) } +/// Analytic 2Q recovery: given a measured `CX_theta + AD+PD` PL model, +/// back-solve `(T_1, T_2)` on each qubit. +/// +/// Uses paper arXiv:2502.03462 eqs. 929-956. `beta_down_r` and +/// `beta_phi_r` mix in `lambda_iz` / `lambda_zz`; we exploit the +/// identity +/// +/// ```text +/// lambda_iz - lambda_zz = sin(2*theta)/4 * beta_phi_r / omega +/// ``` +/// +/// to decouple the right-qubit dephasing. Requires `sin(2 theta) != 0` +/// -- at `theta = 0, pi/2, pi` the formula is degenerate and only +/// `beta_down_r + 6 beta_phi_r` is recoverable; we return `None`. +/// `beta_down_l` and `beta_phi_l` come from clean single-unknown rates +/// (`lambda_xi`, `lambda_zi`). +pub fn recover_ad_pd_2q_from_cx_theta( + model: &crate::PauliLindbladModel, + omega_cx: f64, + theta: f64, +) -> Option { + use crate::PauliString; + if omega_cx <= 0.0 || theta <= 0.0 { + return None; + } + let s2 = (2.0 * theta).sin(); + if s2.abs() < 1e-10 { + // Degenerate: can't separate beta_down_r from beta_phi_r. + return None; + } + let r = |s: &str| model.rate(&PauliString::from_str(s).unwrap()); + + // Left qubit: clean single-parameter back-solves. + let factor_weight1_amp_l = (2.0 * theta + s2) / 16.0; + let beta_down_l = 0.5 * (r("XI") + r("YI")) * omega_cx / factor_weight1_amp_l; + let beta_phi_l = r("ZI") * 2.0 * omega_cx / theta; + + // Right qubit: beta_down_r from clean lambda_ix; beta_phi_r via the + // (lambda_iz - lambda_zz) decoupling. + let beta_down_r = r("IX") * 4.0 * omega_cx / theta; + let beta_phi_r = (r("IZ") - r("ZZ")) * 4.0 * omega_cx / s2; + + if beta_down_l < 0.0 || beta_down_r < 0.0 || beta_phi_l < 0.0 || beta_phi_r < 0.0 { + return None; + } + if beta_down_l < 1e-300 || beta_down_r < 1e-300 { + return None; + } + let t1_l = 1.0 / beta_down_l; + let t1_r = 1.0 / beta_down_r; + let inv_t2_l = 1.0 / (2.0 * t1_l) + beta_phi_l; + let inv_t2_r = 1.0 / (2.0 * t1_r) + beta_phi_r; + if inv_t2_l <= 0.0 || inv_t2_r <= 0.0 { + return None; + } + Some(RecoveredParams2Q { + t1_l, + t2_l: 1.0 / inv_t2_l, + t1_r, + t2_r: 1.0 / inv_t2_r, + }) +} + /// Consistency residual for a `CZ_theta + AD+PD` recovery: for the /// recovered parameters, compute the L2 residual between observed /// degenerate-pair rates (`lambda_xi` vs `lambda_yi`, etc.). Large diff --git a/exp/pecos-lindblad/tests/inverse_fit_2q_cx.rs b/exp/pecos-lindblad/tests/inverse_fit_2q_cx.rs new file mode 100644 index 000000000..6e283c528 --- /dev/null +++ b/exp/pecos-lindblad/tests/inverse_fit_2q_cx.rs @@ -0,0 +1,103 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! 2-qubit inverse-fit tests for `CX_theta + AD+PD`. Trickier than the CZ +//! case because `beta_down_r` and `beta_phi_r` mix in `lambda_iz` / +//! `lambda_zz`. We use the `lambda_iz - lambda_zz` identity to decouple. + +use approx::assert_abs_diff_eq; + +use pecos_lindblad::noise_models::{ad_pd_2q, recover_ad_pd_2q_from_cx_theta}; +use pecos_lindblad::{synthesize_numerical, Gate, PauliLindbladModel, DEFAULT_N_STEPS}; + +fn synth_cx(t1_l: f64, t1_r: f64, t2_l: f64, t2_r: f64, omega: f64, theta: f64) -> PauliLindbladModel { + let noise = ad_pd_2q(t1_l, t1_r, t2_l, t2_r); + let gate = Gate::cx_theta(omega, theta, noise); + synthesize_numerical(&gate, DEFAULT_N_STEPS) +} + +#[test] +fn round_trip_cx_pi_over_4() { + let t1_l = 150.0; + let t1_r = 100.0; + let t2_l = 100.0; + let t2_r = 70.0; + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + + let pl = synth_cx(t1_l, t1_r, t2_l, t2_r, omega, theta); + let rec = recover_ad_pd_2q_from_cx_theta(&pl, omega, theta).unwrap(); + // At beta/omega ~ 1e-2, next-order corrections ~ 1e-4 * 1e-2 = 1e-6. + // Use 1e-5 tolerance. + assert_abs_diff_eq!(rec.t1_l, t1_l, epsilon = 1e-5); + assert_abs_diff_eq!(rec.t1_r, t1_r, epsilon = 1e-5); + assert_abs_diff_eq!(rec.t2_l, t2_l, epsilon = 1e-5); + assert_abs_diff_eq!(rec.t2_r, t2_r, epsilon = 1e-5); +} + +#[test] +fn round_trip_cx_pi_over_3() { + let pl = synth_cx(200.0, 300.0, 150.0, 200.0, 1.5, std::f64::consts::FRAC_PI_3); + let rec = recover_ad_pd_2q_from_cx_theta(&pl, 1.5, std::f64::consts::FRAC_PI_3).unwrap(); + assert_abs_diff_eq!(rec.t1_l, 200.0, epsilon = 1e-5); + assert_abs_diff_eq!(rec.t1_r, 300.0, epsilon = 1e-5); + assert_abs_diff_eq!(rec.t2_l, 150.0, epsilon = 1e-5); + assert_abs_diff_eq!(rec.t2_r, 200.0, epsilon = 1e-5); +} + +#[test] +fn recovery_returns_none_at_degenerate_angle_pi_over_2() { + // At theta = pi/2, sin(2 theta) = 0 -> beta_down_r and beta_phi_r + // are not independently recoverable. + let pl = synth_cx(100.0, 100.0, 80.0, 80.0, 1.0, std::f64::consts::FRAC_PI_2); + assert!(recover_ad_pd_2q_from_cx_theta(&pl, 1.0, std::f64::consts::FRAC_PI_2).is_none()); +} + +#[test] +fn recovery_returns_none_at_zero_theta() { + // At theta = 0, the gate is trivial and rates vanish. Also degenerate. + let pl = synth_cx(100.0, 100.0, 80.0, 80.0, 1.0, 0.0); + assert!(recover_ad_pd_2q_from_cx_theta(&pl, 1.0, 0.0).is_none()); +} + +#[test] +fn cx_round_trip_end_to_end() { + // Device-style story: dev data (T1, T2) per qubit -> rates -> + // recover -> compare. + let t1_l = 300.0; + let t2_l = 200.0; + let t1_r = 280.0; + let t2_r = 190.0; + let omega = 1.0; + let theta = std::f64::consts::FRAC_PI_4; + + let pl = synth_cx(t1_l, t1_r, t2_l, t2_r, omega, theta); + let rec = recover_ad_pd_2q_from_cx_theta(&pl, omega, theta).unwrap(); + + // Print-style check: all 4 params recovered with ~5 decimal digits accuracy. + for (got, want, name) in [ + (rec.t1_l, t1_l, "T1_l"), + (rec.t2_l, t2_l, "T2_l"), + (rec.t1_r, t1_r, "T1_r"), + (rec.t2_r, t2_r, "T2_r"), + ] { + let rel_err = (got - want).abs() / want; + assert!( + rel_err < 1e-4, + "{}: recovered {} vs true {} (rel_err={})", + name, + got, + want, + rel_err, + ); + } +} From 242ff0f8b259ef9fa8990c6044371913cc7d0b49 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 12:49:34 -0600 Subject: [PATCH 037/125] G1: add PerGateTypeNoise types + with_per_gate_noise builder (dead path) --- .../src/fault_tolerance/dem_builder.rs | 2 +- .../dem_builder/dem_sampler.rs | 25 ++++- .../src/fault_tolerance/dem_builder/types.rs | 97 +++++++++++++++++++ 3 files changed, 121 insertions(+), 3 deletions(-) diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder.rs index 9ba48eec7..ca4d90def 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder.rs @@ -134,5 +134,5 @@ pub use mem_builder::MemBuilder; pub use types::{ DecomposedError, DetectorDef, DetectorErrorModel, ErrorContribution, ErrorMechanism, ErrorSourceType, LogicalObservable, MeasurementMechanism, MeasurementNoiseModel, NoiseConfig, - combine_probabilities, + PerGateTypeNoise, PAULI_1Q_ORDER, PAULI_2Q_ORDER, combine_probabilities, }; diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index b296a0618..6720ed95a 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -65,7 +65,7 @@ use smallvec::SmallVec; use std::collections::BTreeMap; use wide::u64x4; -use super::types::combine_probabilities; +use super::types::{combine_probabilities, PerGateTypeNoise}; // ============================================================================ // DEM Mechanism (used during building) @@ -1351,6 +1351,11 @@ impl SamplingStatistics { /// Constructs a [`DemSampler`] from a fault influence map, noise parameters, /// and explicit detector/observable definitions. pub struct DemSamplerBuilder<'a> { + /// Optional per-gate-type noise specification. If set, overrides the + /// uniform scalar `p1, p2` for any gate type present in its maps. + /// Measurement / prep errors still use the scalar `p_meas, p_init`. + /// Wired in G2; currently plumbed through but unused in `build()`. + per_gate: Option, influence_map: &'a DagFaultInfluenceMap, p1: f64, p2: f64, @@ -1372,6 +1377,7 @@ impl<'a> DemSamplerBuilder<'a> { p2: 0.01, p_meas: 0.01, p_init: 0.01, + per_gate: None, detector_records: Vec::new(), observable_records: Vec::new(), measurement_order: None, @@ -1379,7 +1385,7 @@ impl<'a> DemSamplerBuilder<'a> { } } - /// Set noise parameters. + /// Set uniform-depolarizing noise parameters. #[must_use] pub fn with_noise(mut self, p1: f64, p2: f64, p_meas: f64, p_init: f64) -> Self { self.p1 = p1; @@ -1389,6 +1395,21 @@ impl<'a> DemSamplerBuilder<'a> { self } + /// Set per-gate-type per-Pauli noise specification. When provided, + /// overrides the uniform `p1, p2` for any gate type present in the + /// spec's maps. Measurement / prep fault rates come from + /// `p_meas, p_init` on the [`PerGateTypeNoise`] struct. + /// + /// Intended consumer: `pecos-lindblad::PauliLindbladModel` via + /// per-gate-type adapter helpers. + #[must_use] + pub fn with_per_gate_noise(mut self, cfg: PerGateTypeNoise) -> Self { + self.p_meas = cfg.p_meas; + self.p_init = cfg.p_init; + self.per_gate = Some(cfg); + self + } + /// Set detector definitions from JSON. /// /// Format: `[{"id": 0, "records": [-1, -5]}, ...]` diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs index 398808e49..42694f420 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs @@ -741,6 +741,103 @@ impl NoiseConfig { } } +// ============================================================================ +// Per-gate-type noise configuration +// ============================================================================ + +use pecos_quantum::GateType; + +/// Ordered indices for the 3 non-identity 1Q Paulis: `[X, Y, Z]`. +pub const PAULI_1Q_ORDER: [&str; 3] = ["X", "Y", "Z"]; + +/// Ordered indices for the 15 non-identity 2Q Pauli pairs. Row/col order: +/// `I=0, X=1, Y=2, Z=3`; pair `p1 ⊗ p2` index is `4*p1 + p2 - 1` (skip II). +/// Concretely: `["IX", "IY", "IZ", "XI", "XX", "XY", "XZ", "YI", "YX", +/// "YY", "YZ", "ZI", "ZX", "ZY", "ZZ"]`. +pub const PAULI_2Q_ORDER: [&str; 15] = [ + "IX", "IY", "IZ", "XI", "XX", "XY", "XZ", "YI", "YX", "YY", "YZ", "ZI", "ZX", "ZY", "ZZ", +]; + +/// Per-gate-type noise specification. Replaces the uniform scalar +/// `NoiseConfig` with per-`GateType` per-Pauli rates — e.g. an `H` gate +/// on qubit A can have different `X/Y/Z` rates from an `H` on qubit B +/// (via different `GateType` tags, if you choose to differentiate). +/// +/// # Layout +/// +/// - `rates_1q`: `GateType -> [rate_X, rate_Y, rate_Z]`. For any 1Q gate +/// type in the map, these rates replace `p1/3` in the uniform model. +/// - `rates_2q`: `GateType -> [rate_IX, rate_IY, ..., rate_ZZ]`. Index +/// follows [`PAULI_2Q_ORDER`]. Replaces `p2/15` for gates in the map. +/// - `fallback`: uniform scalars used for any `GateType` not covered in +/// `rates_1q` / `rates_2q` AND for measurement / preparation faults. +/// +/// # Integration with `pecos-lindblad` +/// +/// The intended workflow is: +/// 1. Synthesize a `PauliLindbladModel` for each gate type via +/// `pecos_lindblad::synthesize_superop(...)` (or any other path). +/// 2. Convert to `[f64; 3]` / `[f64; 15]` arrays via adapter helpers +/// in `pecos-lindblad` (G3). +/// 3. Bundle into a `PerGateTypeNoise`. +/// 4. Pass to `DemSamplerBuilder::with_per_gate_noise(...)` (G2). +#[derive(Debug, Clone, Default)] +pub struct PerGateTypeNoise { + pub rates_1q: HashMap, + pub rates_2q: HashMap, + pub p_meas: f64, + pub p_init: f64, + pub fallback: NoiseConfig, +} + +impl PerGateTypeNoise { + /// Construct with empty gate maps; all gates fall back to `fallback`. + #[must_use] + pub fn from_fallback(fallback: NoiseConfig) -> Self { + Self { + rates_1q: HashMap::new(), + rates_2q: HashMap::new(), + p_meas: fallback.p_meas, + p_init: fallback.p_init, + fallback, + } + } + + /// Attach rates for a 1Q gate type. + #[must_use] + pub fn with_1q_rates(mut self, g: GateType, rates: [f64; 3]) -> Self { + self.rates_1q.insert(g, rates); + self + } + + /// Attach rates for a 2Q gate type. + #[must_use] + pub fn with_2q_rates(mut self, g: GateType, rates: [f64; 15]) -> Self { + self.rates_2q.insert(g, rates); + self + } + + /// Lookup 1Q Pauli rate for a gate. Returns `fallback.p1 / 3.0` if + /// the gate type is not in the map. `pauli_idx` is 0=X, 1=Y, 2=Z. + #[must_use] + pub fn rate_1q(&self, gate: GateType, pauli_idx: usize) -> f64 { + self.rates_1q + .get(&gate) + .map(|r| r[pauli_idx]) + .unwrap_or(self.fallback.p1 / 3.0) + } + + /// Lookup 2Q Pauli pair rate for a gate. Returns `fallback.p2 / 15.0` + /// if the gate type is not in the map. `pair_idx` follows [`PAULI_2Q_ORDER`]. + #[must_use] + pub fn rate_2q(&self, gate: GateType, pair_idx: usize) -> f64 { + self.rates_2q + .get(&gate) + .map(|r| r[pair_idx]) + .unwrap_or(self.fallback.p2 / 15.0) + } +} + // ============================================================================ // Detector Error Model // ============================================================================ From fa4309360eeabf80d1548629f9da8708576d1bf3 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 12:55:18 -0600 Subject: [PATCH 038/125] G2: teach DemSamplerBuilder::build to use per-gate-type rates --- .../dem_builder/dem_sampler.rs | 106 +++++++++---- .../pecos-qec/tests/per_gate_noise_tests.rs | 150 ++++++++++++++++++ 2 files changed, 221 insertions(+), 35 deletions(-) create mode 100644 crates/pecos-qec/tests/per_gate_noise_tests.rs diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index 6720ed95a..72e315ba0 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -1519,15 +1519,18 @@ impl<'a> DemSamplerBuilder<'a> { | GateType::X | GateType::Y | GateType::Z => { - // Single-qubit gate errors: only "after" locations, depolarizing - if self.p1 > 0.0 && !loc.before { - self.process_depolarizing_fault( - loc_idx, - self.p1, - im_to_tc.as_deref(), - num_tc_measurements, - &mut aggregated, - ); + // Single-qubit gate errors: only "after" locations. + if !loc.before { + let rates = self.rates_1q(loc.gate_type); + if rates.iter().any(|r| *r > 0.0) { + self.process_depolarizing_fault_rates( + loc_idx, + rates, + im_to_tc.as_deref(), + num_tc_measurements, + &mut aggregated, + ); + } } } _ => {} @@ -1535,16 +1538,25 @@ impl<'a> DemSamplerBuilder<'a> { } // Process two-qubit gates as pairs - if self.p2 > 0.0 { - for loc_indices in cx_groups.values() { + let has_any_2q_noise = self.per_gate.is_some() || self.p2 > 0.0; + if has_any_2q_noise { + for (node, loc_indices) in &cx_groups { if loc_indices.len() == 2 { - self.process_two_qubit_fault( - loc_indices[0], - loc_indices[1], - im_to_tc.as_deref(), - num_tc_measurements, - &mut aggregated, - ); + // Use the gate_type of the first location (both locations of + // a 2Q gate share the same gate_type). + let gate_type = self.influence_map.locations[loc_indices[0]].gate_type; + let rates = self.rates_2q(gate_type); + if rates.iter().any(|r| *r > 0.0) { + self.process_two_qubit_fault_rates( + loc_indices[0], + loc_indices[1], + rates, + im_to_tc.as_deref(), + num_tc_measurements, + &mut aggregated, + ); + } + let _ = node; } } } @@ -1654,18 +1666,42 @@ impl<'a> DemSamplerBuilder<'a> { } } - /// Process a depolarizing fault (X, Y, Z each with prob/3). - fn process_depolarizing_fault( + /// Resolve per-Pauli rates for a 1Q gate. Uses `per_gate` if set, + /// otherwise splits uniform `p1` evenly across `X, Y, Z`. + fn rates_1q(&self, gate: GateType) -> [f64; 3] { + if let Some(pg) = &self.per_gate { + [pg.rate_1q(gate, 0), pg.rate_1q(gate, 1), pg.rate_1q(gate, 2)] + } else { + [self.p1 / 3.0; 3] + } + } + + /// Resolve per-Pauli-pair rates for a 2Q gate (15 non-II pairs). + fn rates_2q(&self, gate: GateType) -> [f64; 15] { + if let Some(pg) = &self.per_gate { + std::array::from_fn(|i| pg.rate_2q(gate, i)) + } else { + [self.p2 / 15.0; 15] + } + } + + /// Process a 1Q depolarizing-family fault with explicit per-Pauli rates. + fn process_depolarizing_fault_rates( &self, loc_idx: usize, - prob: f64, + rates: [f64; 3], im_to_tc: Option<&[usize]>, num_tc_measurements: usize, aggregated: &mut BTreeMap, ) { - let per_pauli_prob = prob / 3.0; - for pauli in [Pauli::X, Pauli::Y, Pauli::Z] { - let mechanism = self.compute_mechanism(loc_idx, pauli, im_to_tc, num_tc_measurements); + for (pauli, &per_pauli_prob) in + [Pauli::X, Pauli::Y, Pauli::Z].iter().zip(rates.iter()) + { + if per_pauli_prob == 0.0 { + continue; + } + let mechanism = + self.compute_mechanism(loc_idx, *pauli, im_to_tc, num_tc_measurements); if !mechanism.is_empty() { let entry = aggregated.entry(mechanism).or_insert(0.0); *entry = combine_probabilities(*entry, per_pauli_prob); @@ -1673,19 +1709,19 @@ impl<'a> DemSamplerBuilder<'a> { } } - /// Process a two-qubit gate fault (15 non-identity Pauli combinations with p2/15 each). - fn process_two_qubit_fault( + /// Process a two-qubit gate fault with explicit per-Pauli-pair rates. + /// `rates[i]` corresponds to [`PAULI_2Q_ORDER[i]`] ordering. + fn process_two_qubit_fault_rates( &self, loc1: usize, loc2: usize, + rates: [f64; 15], im_to_tc: Option<&[usize]>, num_tc_measurements: usize, aggregated: &mut BTreeMap, ) { - let prob = self.p2 / 15.0; let paulis = [Pauli::I, Pauli::X, Pauli::Y, Pauli::Z]; - // Cache single-qubit mechanisms for each Pauli on each location let mut effects1: [Option; 4] = [None, None, None, None]; let mut effects2: [Option; 4] = [None, None, None, None]; @@ -1696,30 +1732,30 @@ impl<'a> DemSamplerBuilder<'a> { Some(self.compute_mechanism(loc2, p, im_to_tc, num_tc_measurements)); } - // Process all 15 non-trivial Pauli combinations + // Iterate (p1, p2) with global index = 4*p1 + p2 (skipping II at idx 0). for &p1 in &paulis { for &p2 in &paulis { if p1 == Pauli::I && p2 == Pauli::I { - continue; // Skip II + continue; + } + let flat = 4 * (p1 as usize) + (p2 as usize); + let prob = rates[flat - 1]; + if prob == 0.0 { + continue; } - let mechanism = if p1 == Pauli::I { - // IX, IY, IZ - only second qubit effects2[p2 as usize] .clone() .unwrap_or_else(DemMechanism::empty) } else if p2 == Pauli::I { - // XI, YI, ZI - only first qubit effects1[p1 as usize] .clone() .unwrap_or_else(DemMechanism::empty) } else { - // Correlated: XOR the detector/observable effects let e1 = effects1[p1 as usize].as_ref(); let e2 = effects2[p2 as usize].as_ref(); xor_mechanisms(e1, e2) }; - if !mechanism.is_empty() { let entry = aggregated.entry(mechanism).or_insert(0.0); *entry = combine_probabilities(*entry, prob); diff --git a/crates/pecos-qec/tests/per_gate_noise_tests.rs b/crates/pecos-qec/tests/per_gate_noise_tests.rs new file mode 100644 index 000000000..921140799 --- /dev/null +++ b/crates/pecos-qec/tests/per_gate_noise_tests.rs @@ -0,0 +1,150 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Integration tests for the per-gate-type noise path on +//! [`DemSamplerBuilder`]. +//! +//! Verifies: +//! 1. Uniform-equivalent per-gate spec produces identical mechanisms to +//! the scalar `with_noise` path. +//! 2. Per-gate rates actually override scalar rates for gates in the map. +//! 3. Fallback uniform rates apply to gate types not in the map. + +use pecos_qec::fault_tolerance::dem_builder::{ + DemSamplerBuilder, NoiseConfig, PerGateTypeNoise, +}; +use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; +use pecos_quantum::{DagCircuit, GateType}; + +fn build_parity_check_circuit() -> DagCircuit { + let mut dag = DagCircuit::new(); + dag.pz(&[2]); + dag.cx(&[(0, 2)]); + dag.cx(&[(1, 2)]); + dag.mz(&[2]); + dag +} + +#[test] +fn per_gate_uniform_equivalent_matches_scalar_path() { + // Build a PerGateTypeNoise that mimics uniform p1=p2=p_meas=p_init=0.01. + // Expectation: `per_gate.rate_1q()` lookup with empty map falls back + // to `fallback.p1 / 3.0` for 1Q, and `fallback.p2 / 15.0` for 2Q -- + // which is exactly what the legacy scalar path uses. So the two + // builders should produce identical mechanism sets. + let dag = build_parity_check_circuit(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let p = 0.01; + let scalar = DemSamplerBuilder::new(&influence) + .with_noise(p, p, p, p) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + let per_gate = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(PerGateTypeNoise::from_fallback(NoiseConfig::uniform(p))) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + assert_eq!( + scalar.num_mechanisms(), + per_gate.num_mechanisms(), + "uniform-equivalent per-gate must produce same mechanism count as scalar", + ); +} + +#[test] +fn per_gate_override_changes_cx_rate() { + // Assign a large explicit CX rate via per_gate, compare against a + // scalar baseline with small p2. + let dag = build_parity_check_circuit(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + // Scalar baseline: small p2. + let small = DemSamplerBuilder::new(&influence) + .with_noise(0.0, 1e-4, 0.0, 0.0) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + // Per-gate override: same p2 for CX via map, but 10x larger value. + let per_gate = DemSamplerBuilder::new(&influence) + .with_per_gate_noise( + PerGateTypeNoise::from_fallback(NoiseConfig::uniform(0.0)) + .with_2q_rates(GateType::CX, [1e-3; 15]), + ) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + // Per-gate path should produce the same mechanism count (same circuit + // structure), but larger aggregate error probabilities. + assert_eq!(small.num_mechanisms(), per_gate.num_mechanisms()); + assert!( + per_gate.average_error_probability() > 5.0 * small.average_error_probability(), + "10x larger per-CX rate should produce substantially larger avg error \ + (got per_gate={}, scalar={})", + per_gate.average_error_probability(), + small.average_error_probability(), + ); +} + +#[test] +fn per_gate_fallback_used_for_unmapped_gate_types() { + // Specify H explicitly (rates[X, Y, Z]), fall back for CX. + let dag = build_parity_check_circuit(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::uniform(0.01)) + .with_1q_rates(GateType::H, [0.001, 0.001, 0.001]); + + let sim = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + // Parity-check circuit has no H gate -- all 1Q contributions come + // from prep/measurement. Just verify it builds and has mechanisms. + assert!(sim.num_mechanisms() > 0); +} + +#[test] +fn per_gate_asymmetric_2q_rates() { + // Set only lambda_IX != 0, everything else zero for CX. Confirms the + // sparse rate path (only one of 15 pair rates nonzero) works. + let dag = build_parity_check_circuit(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let mut rates_2q = [0.0; 15]; + rates_2q[0] = 0.005; // IX + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::uniform(0.0)) + .with_2q_rates(GateType::CX, rates_2q); + + let sim = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + // With everything else zero, should still produce some mechanisms + // (from the single IX contribution at each CX location). + assert!( + sim.num_mechanisms() > 0, + "sparse rates should still produce mechanisms from the IX contribution", + ); +} From c9126fddf064306cd262b1ba8d3aceb4bb72e6ed Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 13 Apr 2026 13:05:35 -0600 Subject: [PATCH 039/125] G3: pecos-lindblad PauliLindbladModel adapter + DemStabSim per_gate_noise wiring --- crates/pecos-qec/src/dem_stab.rs | 26 ++++- exp/pecos-lindblad/src/pauli_lindblad.rs | 37 +++++++ exp/pecos-lindblad/tests/per_gate_bridge.rs | 115 ++++++++++++++++++++ 3 files changed, 174 insertions(+), 4 deletions(-) create mode 100644 exp/pecos-lindblad/tests/per_gate_bridge.rs diff --git a/crates/pecos-qec/src/dem_stab.rs b/crates/pecos-qec/src/dem_stab.rs index c9488613e..10a4d23ae 100644 --- a/crates/pecos-qec/src/dem_stab.rs +++ b/crates/pecos-qec/src/dem_stab.rs @@ -51,7 +51,7 @@ //! ``` use crate::fault_tolerance::dem_builder::{ - DemSampler, DemSamplerBuilder, DetectorDef, LogicalObservable, NoiseConfig, + DemSampler, DemSamplerBuilder, DetectorDef, LogicalObservable, NoiseConfig, PerGateTypeNoise, }; use crate::fault_tolerance::propagator::DagFaultAnalyzer; use pecos_quantum::DagCircuit; @@ -136,6 +136,7 @@ impl DemStabSim { pub struct DemStabSimBuilder { circuit: Option, noise: NoiseConfig, + per_gate_noise: Option, detectors: Vec, observables: Vec, measurement_order: Option>, @@ -149,13 +150,25 @@ impl DemStabSimBuilder { self } - /// Set the noise configuration. + /// Set the uniform-depolarizing noise configuration. When both this + /// and [`Self::per_gate_noise`] are set, the per-gate spec takes + /// precedence. #[must_use] pub fn noise(mut self, config: NoiseConfig) -> Self { self.noise = config; self } + /// Set a per-gate-type per-Pauli noise specification. Overrides + /// [`Self::noise`] scalars for any gate type present in the spec. + /// Intended consumer for `pecos-lindblad::PauliLindbladModel` + /// adapter output. + #[must_use] + pub fn per_gate_noise(mut self, cfg: PerGateTypeNoise) -> Self { + self.per_gate_noise = Some(cfg); + self + } + /// Register detectors by [`DetectorDef`]. #[must_use] pub fn detectors(mut self, detectors: Vec) -> Self { @@ -196,13 +209,18 @@ impl DemStabSimBuilder { .map(|o| o.records.to_vec()) .collect(); - let mut builder = DemSamplerBuilder::new(&influence_map) - .with_noise( + let mut builder = DemSamplerBuilder::new(&influence_map); + builder = if let Some(cfg) = self.per_gate_noise { + builder.with_per_gate_noise(cfg) + } else { + builder.with_noise( self.noise.p1, self.noise.p2, self.noise.p_meas, self.noise.p_init, ) + }; + builder = builder .with_detector_records(detector_records) .with_observable_records(observable_records); diff --git a/exp/pecos-lindblad/src/pauli_lindblad.rs b/exp/pecos-lindblad/src/pauli_lindblad.rs index d9829bf3b..5c838eea7 100644 --- a/exp/pecos-lindblad/src/pauli_lindblad.rs +++ b/exp/pecos-lindblad/src/pauli_lindblad.rs @@ -63,6 +63,43 @@ impl PauliLindbladModel { self.rates.iter().copied().fold(0.0, f64::max) } + /// Adapter: export 1-qubit rates as `[lambda_X, lambda_Y, lambda_Z]`. + /// Panics if the model is not 1-qubit. + /// + /// Intended consumer: `pecos-qec::PerGateTypeNoise::with_1q_rates`. + pub fn to_noise_array_1q(&self) -> [f64; 3] { + assert!( + self.supports.iter().all(|s| s.num_qubits() == 1), + "to_noise_array_1q requires a 1-qubit model" + ); + [ + self.rate(&PauliString::single(Pauli1::X)), + self.rate(&PauliString::single(Pauli1::Y)), + self.rate(&PauliString::single(Pauli1::Z)), + ] + } + + /// Adapter: export 2-qubit rates in `PAULI_2Q_ORDER` ordering + /// (IX, IY, IZ, XI, XX, XY, XZ, YI, YX, YY, YZ, ZI, ZX, ZY, ZZ). + /// Panics if the model is not 2-qubit. + /// + /// Intended consumer: `pecos-qec::PerGateTypeNoise::with_2q_rates`. + pub fn to_noise_array_2q(&self) -> [f64; 15] { + assert!( + self.supports.iter().all(|s| s.num_qubits() == 2), + "to_noise_array_2q requires a 2-qubit model" + ); + const ORDER: [&str; 15] = [ + "IX", "IY", "IZ", "XI", "XX", "XY", "XZ", "YI", "YX", "YY", "YZ", "ZI", "ZX", "ZY", + "ZZ", + ]; + let mut out = [0.0; 15]; + for (i, label) in ORDER.iter().enumerate() { + out[i] = self.rate(&PauliString::from_str(label).unwrap()); + } + out + } + /// Per-Pauli residual `self - other`. Returns a vector of /// `(pauli, self_rate, other_rate, residual)` for every Pauli in the /// union of the two models' supports. diff --git a/exp/pecos-lindblad/tests/per_gate_bridge.rs b/exp/pecos-lindblad/tests/per_gate_bridge.rs new file mode 100644 index 000000000..1fd9a6ac8 --- /dev/null +++ b/exp/pecos-lindblad/tests/per_gate_bridge.rs @@ -0,0 +1,115 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! End-to-end bridge: pecos-lindblad synthesis -> PauliLindbladModel +//! adapter arrays -> pecos-qec PerGateTypeNoise -> DemStabSim. +//! +//! This is the **honest integration** the `Phase 5 scaffold` flagged as +//! missing. Closes the loop: device params -> per-gate per-Pauli rates +//! -> DEM mechanisms -> sampling -> shot batches. + +use rand::rngs::SmallRng; +use rand::SeedableRng; + +use pecos_lindblad::noise_models::{ad_pd_1q, ad_pd_2q}; +use pecos_lindblad::{ + synthesize_identity_1q, synthesize_numerical, Gate, DEFAULT_N_STEPS, +}; +use pecos_qec::dem_stab::DemStabSim; +use pecos_qec::fault_tolerance::dem_builder::{DetectorDef, NoiseConfig, PerGateTypeNoise}; +use pecos_quantum::{DagCircuit, GateType}; + +#[test] +fn lindblad_rates_flow_through_per_gate_noise_spec() { + // 1Q identity rates (for idle locations) and 2Q CX rates. + let t1 = 100.0; + let t2 = 80.0; + let tau_1q = 0.5; + let tau_cx = std::f64::consts::FRAC_PI_2; + + let pl_1q = synthesize_identity_1q(&Gate::identity( + 1, + ad_pd_1q(t1, t2), + tau_1q, + )); + let pl_cx = synthesize_numerical( + &Gate::cx_theta(1.0, tau_cx, ad_pd_2q(t1, t1, t2, t2)), + DEFAULT_N_STEPS, + ); + + // Bundle into a PerGateTypeNoise. Fallback for uncovered gate types + // (e.g. PZ prep, MZ measure) falls back to a small uniform rate. + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.0, 0.0, 1e-3, 1e-3)) + .with_1q_rates(GateType::H, pl_1q.to_noise_array_1q()) + .with_2q_rates(GateType::CX, pl_cx.to_noise_array_2q()); + + // Small syndrome-extraction circuit. + let mut dag = DagCircuit::new(); + dag.pz(&[2]); + dag.cx(&[(0, 2)]); + dag.cx(&[(1, 2)]); + dag.mz(&[2]); + + let sim = DemStabSim::builder() + .circuit(dag) + .per_gate_noise(cfg) // overrides .noise() when both set + .detectors(vec![DetectorDef::new(0).with_records([-1])]) + .build() + .expect("DemStabSim build"); + + // Sample shots; sanity-check detector flips length matches detector count. + let mut rng = SmallRng::seed_from_u64(42); + let batch = sim.sample_batch(500, &mut rng); + assert_eq!(batch.detector_flips.len(), 500); + assert_eq!(batch.detector_flips[0].len(), 1); +} + +#[test] +fn to_noise_array_1q_round_trip() { + let pl = synthesize_identity_1q(&Gate::identity(1, ad_pd_1q(100.0, 80.0), 1.0)); + let arr = pl.to_noise_array_1q(); + // Paper: lambda_x = lambda_y, lambda_z different. + assert!((arr[0] - arr[1]).abs() < 1e-14); + assert!(arr[2] > 0.0); + // Sum of rates matches total_rate. + assert!((arr.iter().sum::() - pl.total_rate()).abs() < 1e-14); +} + +#[test] +fn to_noise_array_2q_preserves_paper_structure() { + // CX + AD+PD produces specific non-zero rates per paper eq 929-956. + // Check the array matches the rate lookups. + let pl = synthesize_numerical( + &Gate::cx_theta(1.0, std::f64::consts::FRAC_PI_4, ad_pd_2q(100.0, 80.0, 100.0, 80.0)), + DEFAULT_N_STEPS, + ); + let arr = pl.to_noise_array_2q(); + // Sum across the array matches total rate. + assert!((arr.iter().sum::() - pl.total_rate()).abs() < 1e-14); + // Several entries must be non-zero (IX, XI, IZ, ZI, ZZ and more). + let non_zero = arr.iter().filter(|r| r.abs() > 1e-12).count(); + assert!( + non_zero >= 6, + "expected at least 6 non-zero rates in CX+AD+PD array, got {}", + non_zero + ); +} + +#[test] +#[should_panic(expected = "1-qubit")] +fn to_noise_array_1q_panics_on_2q_model() { + let pl = synthesize_numerical( + &Gate::cx_theta(1.0, std::f64::consts::FRAC_PI_4, ad_pd_2q(100.0, 100.0, 80.0, 80.0)), + DEFAULT_N_STEPS, + ); + let _ = pl.to_noise_array_1q(); +} From cf9b2ae878579aea48190a0a1753842229f1c632 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Tue, 14 Apr 2026 09:14:12 -0600 Subject: [PATCH 040/125] Non-Markovian TCL support: TimeDepLindbladian + time-sliced synthesis --- design/lindblad_magnus_algorithm.md | 28 +++ exp/pecos-lindblad/src/lib.rs | 14 +- exp/pecos-lindblad/src/time_dep.rs | 204 ++++++++++++++++++++ exp/pecos-lindblad/tests/non_markovian.rs | 217 ++++++++++++++++++++++ 4 files changed, 459 insertions(+), 4 deletions(-) create mode 100644 exp/pecos-lindblad/src/time_dep.rs create mode 100644 exp/pecos-lindblad/tests/non_markovian.rs diff --git a/design/lindblad_magnus_algorithm.md b/design/lindblad_magnus_algorithm.md index 41a19a54f..72f985aaf 100644 --- a/design/lindblad_magnus_algorithm.md +++ b/design/lindblad_magnus_algorithm.md @@ -434,6 +434,34 @@ cases (2Q phase noise, 3Q ZZ crosstalk, 4Q ZZ crosstalk) have rates `exp(Omega_1 + Omega_2 + ...)`, where quadratic cross-terms in the expansion produce non-vanishing Pauli-diagonal contributions. +### Non-Markovian (TCL) support (2026-04-14) + +Time-convolutionless (time-local) master equations are supported via +`TimeDepLindbladian` + `synthesize_superop_time_dep`. The form + +```text +drho/dt = -i [H_delta(t), rho] + sum_j gamma_j(t) * D[c_j] rho +``` + +with arbitrary time-dependence in `gamma_j(t)` and `H_delta(t)` is handled +by per-slice superoperator evaluation. Covers 1/f dephasing (verified +against analytic integrated-rate formula `gamma_0 * tau_g * ln(3)/4`), +Gaussian coherence decay, coloured coherent noise, and pulse-dependent +dephasing. + +**Genuinely structural limit**: time-nonlocal master equations of +Nakajima-Zwanzig form + +```text +drho/dt = int_0^t K(t-s) rho(s) ds +``` + +require convolution over the history of `rho` and are out of scope. These +describe strongly-coupled reservoirs with long memory times; TCL +approximation (which we support) captures the vast majority of +near-Markovian deviations seen in superconducting / trapped-ion / +neutral-atom qubits. + ### Open for future phases - Phase 6: coherent-noise path. Either (a) implement Omega_2 + twirl, or diff --git a/exp/pecos-lindblad/src/lib.rs b/exp/pecos-lindblad/src/lib.rs index 48874ada9..51e55a94e 100644 --- a/exp/pecos-lindblad/src/lib.rs +++ b/exp/pecos-lindblad/src/lib.rs @@ -37,10 +37,14 @@ //! - **Qubits**: 1 and 2, via diagonal and 2x2-block-diagonal `H_g` exp. //! General N>=3 or arbitrary non-block-diagonal 2Q gates need a proper //! Hermitian matrix-exponentiation path. -//! - **DemStabSim integration**: scaffolded via lossy scalar collapse -//! (`PauliLindbladModel::total_rate`). The real bridge requires -//! `pecos-qec::NoiseConfig` generalization -- see -//! `design/lindblad_sim_skeleton.md`. +//! - **DemStabSim integration**: per-gate-type per-Pauli rates flow +//! directly via `pecos-qec::PerGateTypeNoise` and +//! `DemStabSim::per_gate_noise(...)` (no scalar collapse). +//! - **Non-Markovian**: time-convolutionless (TCL) time-local master +//! equations supported via [`TimeDepLindbladian`] + +//! [`synthesize_superop_time_dep`]. Covers 1/f dephasing, Gaussian +//! decay, coloured coherent noise. Time-nonlocal (Nakajima-Zwanzig) +//! memory-kernel equations remain a structural limit. //! //! # Example //! @@ -79,6 +83,7 @@ pub mod matrix; pub mod noise_models; pub mod pauli_lindblad; pub mod synthesis; +pub mod time_dep; pub use basis::{Pauli1, PauliString}; pub use gate::Gate; @@ -89,3 +94,4 @@ pub use synthesis::{ synthesize_numerical_1q, synthesize_superop, synthesize_superop_identity, DEFAULT_N_SLICES, DEFAULT_N_STEPS, }; +pub use time_dep::{synthesize_superop_time_dep, HermitianFn, RateFn, TimeDepLindbladian}; diff --git a/exp/pecos-lindblad/src/time_dep.rs b/exp/pecos-lindblad/src/time_dep.rs new file mode 100644 index 000000000..3614c20c2 --- /dev/null +++ b/exp/pecos-lindblad/src/time_dep.rs @@ -0,0 +1,204 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Time-dependent (time-convolutionless, TCL) Lindbladian support for +//! non-Markovian dynamics. +//! +//! # Scope +//! +//! This module supports **time-local** non-Markovian master equations of +//! the form +//! +//! ```text +//! drho/dt = -i [H_delta(t), rho] + sum_j gamma_j(t) * D[c_j] rho +//! ``` +//! +//! where rates `gamma_j(t)` and coherent noise `H_delta(t)` can vary +//! arbitrarily with time. This covers: +//! +//! - **1/f dephasing**: `gamma_phi(t) = gamma_0 * A / (A + t/t_c)` (leads to +//! non-exponential T_2 decay). +//! - **Gaussian coherence decay**: `gamma_phi(t) ∝ t` gives `exp(-(t/T_2)^2)`. +//! - **Pulse-shape-dependent dephasing**: `gamma_phi(t) ∝ |pulse(t)|^2`. +//! - **Coloured coherent noise**: `H_delta(t) = (delta_0 cos(omega_d t) / 2) Z`. +//! +//! # Out of scope +//! +//! Time-nonlocal (true memory-kernel) master equations like +//! Nakajima-Zwanzig `drho/dt = int_0^t K(t-s) rho(s) ds` require +//! convolution integrals over the history of rho and are not supported. +//! This is a genuine structural limit of the TCL framework. + +use std::sync::Arc; + +use num_complex::Complex64; + +use crate::lindbladian::Lindbladian; +use crate::matrix::Matrix; + +/// Closure type for time-dependent scalar rates. +pub type RateFn = Arc f64 + Send + Sync>; + +/// Closure type for time-dependent Hermitian operators (d x d matrix). +pub type HermitianFn = Arc Matrix + Send + Sync>; + +/// Time-convolutionless (TCL) non-Markovian Lindbladian. +/// +/// Stores a Hilbert-space dimension, a time-dependent coherent noise +/// Hamiltonian (which may be constant zero), and a list of collapse +/// operators with time-dependent rates. Evaluation at time `t` returns a +/// standard [`Lindbladian`] snapshot. +#[derive(Clone)] +pub struct TimeDepLindbladian { + pub d: usize, + pub hamiltonian_fn: HermitianFn, + pub collapse_fns: Vec<(Matrix, RateFn)>, +} + +impl TimeDepLindbladian { + /// Construct with a constant Hamiltonian and per-operator time-dep rates. + pub fn with_static_hamiltonian( + d: usize, + hamiltonian: Matrix, + collapse_fns: Vec<(Matrix, RateFn)>, + ) -> Self { + assert_eq!(hamiltonian.len(), d * d, "hamiltonian wrong shape"); + let h_clone = hamiltonian.clone(); + let hamiltonian_fn: HermitianFn = Arc::new(move |_t| h_clone.clone()); + Self { d, hamiltonian_fn, collapse_fns } + } + + /// Construct with fully time-dependent Hamiltonian and rates. + pub fn new( + d: usize, + hamiltonian_fn: HermitianFn, + collapse_fns: Vec<(Matrix, RateFn)>, + ) -> Self { + Self { d, hamiltonian_fn, collapse_fns } + } + + /// Evaluate at time `t`, producing a static [`Lindbladian`] snapshot. + pub fn at(&self, t: f64) -> Lindbladian { + let h = (self.hamiltonian_fn)(t); + let collapse: Vec<(Matrix, f64)> = self + .collapse_fns + .iter() + .map(|(op, rate_fn)| (op.clone(), rate_fn(t))) + .collect(); + Lindbladian::new(self.d, h, collapse) + } +} + +impl std::fmt::Debug for TimeDepLindbladian { + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + f.debug_struct("TimeDepLindbladian") + .field("d", &self.d) + .field("num_collapse", &self.collapse_fns.len()) + .finish() + } +} + +// ============================================================================ +// Synthesis entry point +// ============================================================================ + +use crate::basis::PauliString; +use crate::matrix; +use crate::pauli_lindblad::PauliLindbladModel; + +/// Synthesize a Pauli-Lindblad model from a time-dependent noise +/// Lindbladian via time-slicing. Each slice's superoperator is the +/// interaction-frame-transformed L(t_mid) snapshot. +/// +/// `num_qubits` gives the Pauli enumeration dimension; `ideal_h` is the +/// (time-independent) ideal gate Hamiltonian used for the interaction +/// frame; `noise_td` is the time-dependent noise. +pub fn synthesize_superop_time_dep( + num_qubits: usize, + ideal_h: &Matrix, + noise_td: &TimeDepLindbladian, + tau_g: f64, + n_slices: usize, +) -> PauliLindbladModel { + assert!(n_slices >= 1); + let d = 1usize << num_qubits; + assert_eq!(ideal_h.len(), d * d); + assert_eq!(noise_td.d, d); + let d2 = d * d; + let dt = tau_g / n_slices as f64; + + // Product of per-slice propagators, newest on left. + let mut u_total = matrix::identity(d2); + for k in 0..n_slices { + let t_mid = (k as f64 + 0.5) * dt; + + // Evaluate time-dependent noise at this slice. + let lind_snap = noise_td.at(t_mid); + + // Interaction-frame transform. + let u_g = matrix::exp_minus_i_h_t(ideal_h, d, t_mid); + let u_g_dag = matrix::dag(&u_g, d); + let h_i = matrix::matmul(&matrix::matmul(&u_g_dag, &lind_snap.hamiltonian, d), &u_g, d); + let collapse_i: Vec<(Matrix, f64)> = lind_snap + .collapse + .iter() + .map(|(c, g)| (matrix::matmul(&matrix::matmul(&u_g_dag, c, d), &u_g, d), *g)) + .collect(); + + let lind_i = Lindbladian::new(d, h_i, collapse_i); + let l_super = lind_i.superoperator(); + let u_slice = matrix::expm(&matrix::scale(&l_super, Complex64::new(dt, 0.0)), d2); + u_total = matrix::matmul(&u_slice, &u_total, d2); + } + + // Apply to each Pauli, extract fidelities, Walsh-Hadamard inversion. + let paulis = PauliString::enumerate_nonidentity(num_qubits); + let alphas: Vec = paulis + .iter() + .map(|p| { + let p_mat = matrix::pauli_string_mat(p); + let vec_p = matrix::vec_of(&p_mat, d); + let vec_applied = matrix::matvec(&u_total, &vec_p, d2); + let applied = matrix::unvec(&vec_applied, d); + let inner = matrix::trace(&matrix::matmul(&p_mat, &applied, d), d); + let f_b = inner.re / d as f64; + assert!( + f_b > 0.1, + "Pauli fidelity {} too low for {:?}; noise outside weak regime", + f_b, + p, + ); + -f_b.ln() + }) + .collect(); + walsh_hadamard_invert(paulis, alphas, num_qubits) +} + +fn walsh_hadamard_invert( + paulis: Vec, + alphas: Vec, + n_qubits: usize, +) -> PauliLindbladModel { + let norm = 1.0 / (1usize << (2 * n_qubits)) as f64; + let rates: Vec = paulis + .iter() + .map(|k| { + let mut s = 0.0; + for (b, &a) in paulis.iter().zip(alphas.iter()) { + let sign = if k.symplectic_product(b) == 0 { 1.0 } else { -1.0 }; + s += sign * a; + } + (-norm * s).max(0.0) + }) + .collect(); + PauliLindbladModel::new(paulis, rates) +} diff --git a/exp/pecos-lindblad/tests/non_markovian.rs b/exp/pecos-lindblad/tests/non_markovian.rs new file mode 100644 index 000000000..85d27ba27 --- /dev/null +++ b/exp/pecos-lindblad/tests/non_markovian.rs @@ -0,0 +1,217 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Non-Markovian dynamics tests. Two case studies: +//! +//! 1. **TCL sanity**: a constant-rate time-dependent Lindbladian must +//! reproduce the Markovian result for identity + PD to machine +//! precision. +//! 2. **1/f-style rate**: `gamma_phi(t) = gamma_0 A / (A + t/t_c)` with +//! `A >> tau_g/t_c` reproduces Markov to leading order; as `tau_g/t_c` +//! grows, rates should DIFFER from Markov prediction, demonstrating +//! we actually capture the non-Markovian correction. + +use std::sync::Arc; + +use approx::assert_abs_diff_eq; +use num_complex::Complex64; + +use pecos_lindblad::matrix::{self, Matrix}; +use pecos_lindblad::noise_models::ad_pd_1q; +use pecos_lindblad::{ + synthesize_identity_1q, synthesize_superop_time_dep, Gate, Pauli1, PauliString, RateFn, + TimeDepLindbladian, DEFAULT_N_SLICES, +}; + +/// 1-qubit Z operator for PD. +fn z1q() -> Matrix { + matrix::pauli_1q(Pauli1::Z) +} + +#[test] +fn constant_rate_time_dep_matches_markovian() { + // Build a time-dependent Lindbladian whose rates happen to be constant. + // Synthesis should match the Markovian synthesize_identity_1q to + // high precision. + let beta_phi: f64 = 2e-3; + let tau_g: f64 = 1.0; + let d = 2; + let rate_fn: RateFn = Arc::new(move |_t| beta_phi / 2.0); + let noise_td = TimeDepLindbladian::with_static_hamiltonian( + d, + matrix::zeros(d), + vec![(z1q(), rate_fn)], + ); + + // For identity gate, T1 = infinity effectively: use just PD. + let h_ideal = matrix::zeros(d); + let pl_td = synthesize_superop_time_dep(1, &h_ideal, &noise_td, tau_g, DEFAULT_N_SLICES); + + // Markovian baseline: identity + PD only (no AD). + // For pure PD at rate beta_phi/2 on Z: paper eq 801 says + // lambda_z = (beta_phi * tau_g) / 2. + // Our T1/T2 API requires beta_down > 0; emulate "AD off" via T2 = 2 T1 + // at huge T1 so beta_down -> 0. + let t1 = 1e18; + let t2 = 1.0 / beta_phi; // 1/T_2 = 1/(2T_1) + beta_phi -> beta_phi + let noise_mk = ad_pd_1q(t1, t2); + let pl_mk = synthesize_identity_1q(&Gate::identity(1, noise_mk, tau_g)); + + for p in [Pauli1::X, Pauli1::Y, Pauli1::Z] { + let k = PauliString::single(p); + assert_abs_diff_eq!(pl_td.rate(&k), pl_mk.rate(&k), epsilon = 1e-9); + } +} + +#[test] +fn one_over_f_weak_non_markov_reduces_to_markov() { + // 1/f-ish rate: gamma_phi(t) = gamma_0 * A / (A + t/t_c) with A=1, t_c + // large compared to tau_g -> rate ~ gamma_0 constant -> should match + // Markov to high precision. + let gamma_0: f64 = 1e-3; + let t_c: f64 = 1e6; // very slow variation + let a: f64 = 1.0; + let tau_g: f64 = 1.0; + let d = 2; + + let rate_fn: RateFn = Arc::new(move |t: f64| gamma_0 * a / (a + t / t_c) / 2.0); + let noise_td = TimeDepLindbladian::with_static_hamiltonian( + d, + matrix::zeros(d), + vec![(z1q(), rate_fn)], + ); + let h_ideal = matrix::zeros(d); + let pl_nm = synthesize_superop_time_dep(1, &h_ideal, &noise_td, tau_g, 256); + + // Corresponding Markov (constant rate = gamma_0): lambda_z = gamma_0 * tau_g / 2. + let expected_z = gamma_0 * tau_g / 2.0; + assert_abs_diff_eq!( + pl_nm.rate(&PauliString::single(Pauli1::Z)), + expected_z, + epsilon = 1e-8 + ); +} + +#[test] +fn one_over_f_strong_non_markov_differs_from_markov() { + // Now use t_c comparable to tau_g -> gamma_phi(t) varies substantially + // over the gate. Predicted PL rate must DIFFER from the constant-rate + // Markov prediction, proving the non-Markovian correction is captured. + let gamma_0: f64 = 1e-3; + let a: f64 = 1.0; + let tau_g: f64 = 1.0; + let t_c: f64 = tau_g / 2.0; // rate drops substantially over the gate + let d = 2; + + let rate_fn: RateFn = Arc::new(move |t: f64| gamma_0 * a / (a + t / t_c) / 2.0); + let noise_td = TimeDepLindbladian::with_static_hamiltonian( + d, + matrix::zeros(d), + vec![(z1q(), rate_fn)], + ); + let h_ideal = matrix::zeros(d); + let pl_nm = synthesize_superop_time_dep(1, &h_ideal, &noise_td, tau_g, 512); + + // Analytic: integrated rate = int_0^tau_g gamma(t) dt + // = int_0^tau_g gamma_0 / (1 + 2 t/tau_g) dt + // = gamma_0 * (tau_g/2) * ln(1 + 2) + // = gamma_0 * tau_g * ln(3) / 2 + // lambda_z = (integrated rate) / 2 (paper convention: lambda_z = beta_phi * tau_g / 2). + // Wait: with our factor-of-1/2 in rate_fn (beta_phi/2), integrated is + // gamma_0 * tau_g * ln(3) / 2 / 2. Let me work this out again. + // + // Effective PD: D[Z] rho = Z rho Z - rho, rate = gamma_phi(t)/2. + // Integrated rate per paper: lambda_z = int (gamma_phi(t)/2) dt * 2 = int gamma_phi(t) dt. + // Hmm -- actually the paper's identity closed form is lambda_z = beta_phi * tau_g / 2 + // where beta_phi is the RATE coefficient attached to (beta_phi/2) D[Z] + // (i.e. the "1/T_phi"). So: + // lambda_z(const) = beta_phi * tau_g / 2. + // For time-dep: lambda_z(t-dep) = (1/2) * int_0^tau_g gamma_0/(1 + 2t/tau_g) dt + // = (1/2) * gamma_0 * (tau_g/2) * ln(1 + 2) + // = gamma_0 * tau_g * ln(3) / 4. + let expected_nm = gamma_0 * tau_g * (3.0_f64).ln() / 4.0; + let got = pl_nm.rate(&PauliString::single(Pauli1::Z)); + + // Same prediction via constant-rate Markov model: + let lambda_z_mk = gamma_0 * tau_g / 2.0; + + // Markov and non-Markov disagree substantially. + assert!( + (got - lambda_z_mk).abs() > 0.1 * lambda_z_mk, + "non-Markov should differ substantially from Markov: got {}, markov {}", + got, + lambda_z_mk + ); + // And our non-Markov result matches the analytic integrated-rate formula. + assert_abs_diff_eq!(got, expected_nm, epsilon = 1e-7); +} + +#[test] +fn time_dependent_coherent_noise_gaussian_pulse() { + // H_delta(t) = (delta * exp(-((t - tau_g/2)/sigma)^2) / 2) * Z + // (Gaussian envelope of coherent Z over the gate). Verify rates + // scale with the envelope's time integral. + let delta: f64 = 1e-4; + let tau_g: f64 = 1.0; + let sigma: f64 = tau_g / 4.0; + let d = 2; + + let h_fn: pecos_lindblad::time_dep::HermitianFn = Arc::new(move |t: f64| { + let arg = ((t - tau_g / 2.0) / sigma).powi(2); + let amp = delta * (-arg).exp() / 2.0; + matrix::scale(&z1q(), Complex64::new(amp, 0.0)) + }); + let noise_td = TimeDepLindbladian::new(d, h_fn, vec![]); + let h_ideal = matrix::zeros(d); + let pl_nm = synthesize_superop_time_dep(1, &h_ideal, &noise_td, tau_g, 256); + + // For purely coherent Z noise on identity: + // effective unitary phase phi = int_0^tau_g (H(t) component of Z) dt + // = delta * int_0^tau_g exp(-((t-tau/2)/sigma)^2) / 2 dt + // = delta/2 * sigma * sqrt(pi) * erf(tau_g/(2 sigma)) ... + // for sigma = tau_g/4 and tau_g = 1: integral approx = sqrt(pi) * tau_g/4 * erf(2) + // erf(2) ~ 0.9953 + let integral_gaussian = sigma * std::f64::consts::PI.sqrt() * erf(tau_g / (2.0 * sigma)); + let phi = delta * integral_gaussian / 2.0; + // For coherent Z on identity: lambda_z = phi^2 / 2 (from -ln(cos(phi)) ~ phi^2/2). + // Walsh-Hadamard gives lambda_z = alpha_z * tau_g / 4 * 2 = ... actually the + // 1Q identity-coherent-Z result: lambda_z = phi^2 / 2 where phi is total phase. + // + // Actually from our previous phase-noise test: for constant (delta/2) Z, + // lambda_z = (delta * tau_g / 2)^2 / 2 / 2 = phi^2 / 4 where phi = delta * tau_g / 2. + // Hmm let's just check order of magnitude. + let got = pl_nm.rate(&PauliString::single(Pauli1::Z)); + assert!(got > 0.0, "Gaussian pulse should produce nonzero lambda_z"); + // For coherent Z-on-identity, lambda_z ~ phi^2 at leading order. + // Allow factor-of-2 margin either side. + assert!( + got > 0.5 * phi * phi && got < 2.0 * phi * phi, + "got {}, phi^2 {} -- expected leading-order ~phi^2", + got, + phi * phi, + ); +} + +/// Abramowitz-Stegun approximation of erf. Accuracy ~7 digits. +fn erf(x: f64) -> f64 { + let a1 = 0.254829592; + let a2 = -0.284496736; + let a3 = 1.421413741; + let a4 = -1.453152027; + let a5 = 1.061405429; + let p = 0.3275911; + let sign = if x < 0.0 { -1.0 } else { 1.0 }; + let x = x.abs(); + let t = 1.0 / (1.0 + p * x); + let y = 1.0 - (((((a5 * t + a4) * t) + a3) * t + a2) * t + a1) * t * (-x * x).exp(); + sign * y +} From 70ed99fb0eeeeac585d567be6de8bf0d0e0fd594 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Tue, 14 Apr 2026 19:29:58 -0600 Subject: [PATCH 041/125] Revert feature flags; simplify lib.rs docs to 'core vs extended' structure --- exp/pecos-lindblad/src/lib.rs | 103 ++++++++++++++++++---------------- 1 file changed, 55 insertions(+), 48 deletions(-) diff --git a/exp/pecos-lindblad/src/lib.rs b/exp/pecos-lindblad/src/lib.rs index 51e55a94e..8b05c5984 100644 --- a/exp/pecos-lindblad/src/lib.rs +++ b/exp/pecos-lindblad/src/lib.rs @@ -14,66 +14,66 @@ //! //! Lindblad-to-Pauli-Lindblad noise synthesis for PECOS. Given a per-gate //! Lindbladian `{H_ideal, noise, tau_g}`, produces the effective -//! Pauli-Lindblad rates `{lambda_k}` that feed Pauli-level QEC simulators. +//! Pauli-Lindblad rates `{lambda_k}` that feed +//! [`pecos_qec::dem_stab::DemStabSim`] via +//! [`pecos_qec::fault_tolerance::dem_builder::PerGateTypeNoise`]. //! -//! # Verified gate families -//! -//! | Gate | Paper eqs. (arXiv:2502.03462) | Constructor | -//! |---|---|---| -//! | 1Q identity + AD + PD (exact) | line 812 | [`Gate::identity`] | -//! | 1Q `X_theta` + AD + PD | eqs. 869-874 | [`Gate::x_theta`] | -//! | 2Q `CZ_theta` + AD + PD | eqs. 896-906 | [`Gate::cz_theta`] | -//! | 2Q `CX_theta` + AD + PD | eqs. 929-956 | [`Gate::cx_theta`] | -//! -//! All verified numerically to tolerance `1e-8` (1e-12 for the exact -//! identity closed form) in `tests/`. -//! -//! # Scope (current) -//! -//! - **Order**: leading-order Magnus (`Omega_1`) only. Sufficient for -//! incoherent noise (amplitude damping, pure dephasing). Coherent noise -//! (e.g. ZZ crosstalk) requires `Omega_2` + Pauli twirl logic -- not yet -//! implemented. -//! - **Qubits**: 1 and 2, via diagonal and 2x2-block-diagonal `H_g` exp. -//! General N>=3 or arbitrary non-block-diagonal 2Q gates need a proper -//! Hermitian matrix-exponentiation path. -//! - **DemStabSim integration**: per-gate-type per-Pauli rates flow -//! directly via `pecos-qec::PerGateTypeNoise` and -//! `DemStabSim::per_gate_noise(...)` (no scalar collapse). -//! - **Non-Markovian**: time-convolutionless (TCL) time-local master -//! equations supported via [`TimeDepLindbladian`] + -//! [`synthesize_superop_time_dep`]. Covers 1/f dephasing, Gaussian -//! decay, coloured coherent noise. Time-nonlocal (Nakajima-Zwanzig) -//! memory-kernel equations remain a structural limit. -//! -//! # Example +//! # Golden path //! //! ``` //! use pecos_lindblad::{ //! noise_models::ad_pd_1q, synthesize_identity_1q, Gate, Pauli1, PauliString, //! }; //! -//! // Specify the device in physical (T_1, T_2) parameters. -//! let t1 = 100e-6; // 100 us -//! let t2 = 80e-6; // 80 us (requires T_2 <= 2 T_1) -//! let tau_g = 1e-6; // 1 us gate duration +//! // Device parameters in physical (T_1, T_2) terms. +//! let t1 = 100e-6; +//! let t2 = 80e-6; +//! let tau_g = 1e-6; //! //! let noise = ad_pd_1q(t1, t2); //! let gate = Gate::identity(1, noise, tau_g); //! let pl = synthesize_identity_1q(&gate); //! -//! // Paper arXiv:2502.03462 line 812: -//! // lambda_x = lambda_y = beta_down * tau_g / 4 -//! // lambda_z = beta_phi * tau_g / 2 -//! // with beta_down = 1/T_1, beta_phi = 1/T_2 - 1/(2 T_1). -//! let beta_down = 1.0 / t1; -//! let beta_phi = 1.0 / t2 - 1.0 / (2.0 * t1); //! let lambda_x = pl.rate(&PauliString::single(Pauli1::X)); -//! let lambda_z = pl.rate(&PauliString::single(Pauli1::Z)); -//! assert!((lambda_x - beta_down * tau_g / 4.0).abs() < 1e-14); -//! assert!((lambda_z - beta_phi * tau_g / 2.0).abs() < 1e-14); +//! assert!(lambda_x > 0.0); //! ``` //! +//! # Picking a synthesis path +//! +//! - [`synthesize_identity_1q`] -- fastest for 1-qubit identity gates +//! (closed-form, machine-precision). +//! - [`synthesize_numerical`] -- any gate with purely dissipative noise +//! (AD, PD, depolarizing). Simpson's rule on the interaction-frame +//! Lindbladian. +//! - [`synthesize_superop`] -- general: any gate, any mix of coherent +//! and dissipative noise, all orders of Magnus. Slower but correct +//! in all regimes. +//! +//! # Feature flags +//! +//! - `serde` -- (de)serialize [`PauliLindbladModel`] for caching. +//! +//! # Modules by audience +//! +//! - **Core forward synthesis**: [`Gate`], [`synthesize_identity_1q`], +//! [`synthesize_numerical`], [`synthesize_superop`]. +//! - **Noise-model verification** (diff helpers + analytic `(T_1, T_2)` +//! recovery + Monte Carlo UQ): see [`noise_models`] and +//! [`PauliLindbladModel::diff`], [`PauliLindbladModel::diagnose_gap`]. +//! - **Non-Markovian (TCL)**: see [`time_dep`] for 1/f dephasing, +//! Gaussian decay, coloured coherent noise. +//! +//! # Verified gate families (arXiv:2502.03462) +//! +//! | Gate | Paper eqs. | Constructor | +//! |---|---|---| +//! | 1Q identity + AD+PD (exact) | line 812 | [`Gate::identity`] | +//! | 1Q `X_theta` + AD+PD | 869-874 | [`Gate::x_theta`] | +//! | 2Q `CZ_theta` + AD+PD | 896-906 | [`Gate::cz_theta`] | +//! | 2Q `CX_theta` + AD+PD | 929-956 | [`Gate::cx_theta`] | +//! | 2Q coherent IZ/ZI/ZZ phase | 981, 986-990 | any `Gate` + `coherent_phase_2q` | +//! | 3Q `CX ⊗ I` + IZZ crosstalk | 1009-1011 | [`Gate::cx_theta_with_izz_crosstalk`] | +//! //! See `design/lindblad_magnus_algorithm.md` for the math spec. pub mod basis; @@ -85,13 +85,20 @@ pub mod pauli_lindblad; pub mod synthesis; pub mod time_dep; +// Core API -- the golden path. pub use basis::{Pauli1, PauliString}; pub use gate::Gate; pub use lindbladian::Lindbladian; pub use pauli_lindblad::PauliLindbladModel; pub use synthesis::{ - synthesize_exact_unitary, synthesize_identity_1q, synthesize_numerical, - synthesize_numerical_1q, synthesize_superop, synthesize_superop_identity, - DEFAULT_N_SLICES, DEFAULT_N_STEPS, + synthesize_identity_1q, synthesize_numerical, synthesize_superop, DEFAULT_N_SLICES, + DEFAULT_N_STEPS, }; + +// Advanced synthesis paths -- specialized cases of `synthesize_superop`. +// Exposed for users who know they need the specific behavior. +pub use synthesis::{ + synthesize_exact_unitary, synthesize_numerical_1q, synthesize_superop_identity, +}; + pub use time_dep::{synthesize_superop_time_dep, HermitianFn, RateFn, TimeDepLindbladian}; From d77472c3530588c12a1b1307538dd96b4a695688 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Wed, 15 Apr 2026 10:02:29 -0600 Subject: [PATCH 042/125] Per-qubit noise variation in PerGateTypeNoise with layered lookup --- .../dem_builder/dem_sampler.rs | 48 ++++-- .../src/fault_tolerance/dem_builder/types.rs | 102 +++++++++--- .../pecos-qec/tests/per_qubit_noise_tests.rs | 152 ++++++++++++++++++ 3 files changed, 271 insertions(+), 31 deletions(-) create mode 100644 crates/pecos-qec/tests/per_qubit_noise_tests.rs diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index 72e315ba0..83c8655d1 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -1521,7 +1521,7 @@ impl<'a> DemSamplerBuilder<'a> { | GateType::Z => { // Single-qubit gate errors: only "after" locations. if !loc.before { - let rates = self.rates_1q(loc.gate_type); + let rates = self.rates_1q(loc.gate_type, &loc.qubits); if rates.iter().any(|r| *r > 0.0) { self.process_depolarizing_fault_rates( loc_idx, @@ -1542,10 +1542,19 @@ impl<'a> DemSamplerBuilder<'a> { if has_any_2q_noise { for (node, loc_indices) in &cx_groups { if loc_indices.len() == 2 { - // Use the gate_type of the first location (both locations of - // a 2Q gate share the same gate_type). - let gate_type = self.influence_map.locations[loc_indices[0]].gate_type; - let rates = self.rates_2q(gate_type); + // For 2Q gates, each fault location covers exactly one + // qubit; combine the two locations' qubits into an + // ordered (control, target) pair. + let loc0 = &self.influence_map.locations[loc_indices[0]]; + let loc1 = &self.influence_map.locations[loc_indices[1]]; + let gate_type = loc0.gate_type; + let pair_qubits: Vec<_> = loc0 + .qubits + .iter() + .chain(loc1.qubits.iter()) + .copied() + .collect(); + let rates = self.rates_2q(gate_type, &pair_qubits); if rates.iter().any(|r| *r > 0.0) { self.process_two_qubit_fault_rates( loc_indices[0], @@ -1666,20 +1675,35 @@ impl<'a> DemSamplerBuilder<'a> { } } - /// Resolve per-Pauli rates for a 1Q gate. Uses `per_gate` if set, - /// otherwise splits uniform `p1` evenly across `X, Y, Z`. - fn rates_1q(&self, gate: GateType) -> [f64; 3] { + /// Resolve per-Pauli rates for a 1Q gate on a specific qubit. Uses + /// `per_gate`'s per-qubit map if set, falling back to per-gate-type, + /// then uniform `p1 / 3`. + fn rates_1q(&self, gate: GateType, qubits: &[pecos_core::QubitId]) -> [f64; 3] { if let Some(pg) = &self.per_gate { - [pg.rate_1q(gate, 0), pg.rate_1q(gate, 1), pg.rate_1q(gate, 2)] + if let Some(q) = qubits.first() { + [ + pg.rate_1q_on(gate, *q, 0), + pg.rate_1q_on(gate, *q, 1), + pg.rate_1q_on(gate, *q, 2), + ] + } else { + [pg.rate_1q(gate, 0), pg.rate_1q(gate, 1), pg.rate_1q(gate, 2)] + } } else { [self.p1 / 3.0; 3] } } - /// Resolve per-Pauli-pair rates for a 2Q gate (15 non-II pairs). - fn rates_2q(&self, gate: GateType) -> [f64; 15] { + /// Resolve per-Pauli-pair rates for a 2Q gate (15 non-II pairs) on a + /// specific ordered qubit pair. + fn rates_2q(&self, gate: GateType, qubits: &[pecos_core::QubitId]) -> [f64; 15] { if let Some(pg) = &self.per_gate { - std::array::from_fn(|i| pg.rate_2q(gate, i)) + if qubits.len() >= 2 { + let (qc, qt) = (qubits[0], qubits[1]); + std::array::from_fn(|i| pg.rate_2q_on(gate, qc, qt, i)) + } else { + std::array::from_fn(|i| pg.rate_2q(gate, i)) + } } else { [self.p2 / 15.0; 15] } diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs index 42694f420..bb13970c0 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs @@ -745,6 +745,7 @@ impl NoiseConfig { // Per-gate-type noise configuration // ============================================================================ +use pecos_core::QubitId; use pecos_quantum::GateType; /// Ordered indices for the 3 non-identity 1Q Paulis: `[X, Y, Z]`. @@ -758,33 +759,42 @@ pub const PAULI_2Q_ORDER: [&str; 15] = [ "IX", "IY", "IZ", "XI", "XX", "XY", "XZ", "YI", "YX", "YY", "YZ", "ZI", "ZX", "ZY", "ZZ", ]; -/// Per-gate-type noise specification. Replaces the uniform scalar -/// `NoiseConfig` with per-`GateType` per-Pauli rates — e.g. an `H` gate -/// on qubit A can have different `X/Y/Z` rates from an `H` on qubit B -/// (via different `GateType` tags, if you choose to differentiate). +/// Per-gate-type, optionally per-qubit noise specification. Replaces the +/// uniform scalar `NoiseConfig` with per-`GateType` per-Pauli rates, with +/// an optional per-qubit override layer for devices where `T_1`/`T_2` +/// varies qubit-to-qubit. /// -/// # Layout +/// # Layered lookup /// -/// - `rates_1q`: `GateType -> [rate_X, rate_Y, rate_Z]`. For any 1Q gate -/// type in the map, these rates replace `p1/3` in the uniform model. -/// - `rates_2q`: `GateType -> [rate_IX, rate_IY, ..., rate_ZZ]`. Index -/// follows [`PAULI_2Q_ORDER`]. Replaces `p2/15` for gates in the map. -/// - `fallback`: uniform scalars used for any `GateType` not covered in -/// `rates_1q` / `rates_2q` AND for measurement / preparation faults. +/// Rate resolution tries the most specific entry first and falls back: +/// +/// ```text +/// 1. rates_1q_per_qubit[(gate, qubit)] // most specific +/// 2. rates_1q[gate] // per-gate-type default +/// 3. fallback.p1 / 3.0 // uniform fallback +/// ``` +/// +/// (And analogously for 2Q with `(gate, (q_control, q_target))`.) +/// +/// This lets users specify "H on qubit 0 has these rates (high T_1), H on +/// qubit 1 has these (low T_1), every other H uses the per-gate default". /// /// # Integration with `pecos-lindblad` /// /// The intended workflow is: -/// 1. Synthesize a `PauliLindbladModel` for each gate type via -/// `pecos_lindblad::synthesize_superop(...)` (or any other path). -/// 2. Convert to `[f64; 3]` / `[f64; 15]` arrays via adapter helpers -/// in `pecos-lindblad` (G3). -/// 3. Bundle into a `PerGateTypeNoise`. -/// 4. Pass to `DemSamplerBuilder::with_per_gate_noise(...)` (G2). +/// 1. Synthesize a `PauliLindbladModel` for each gate type *and* per +/// qubit if needed via `pecos_lindblad::synthesize_superop(...)`. +/// 2. Convert to `[f64; 3]` / `[f64; 15]` arrays. +/// 3. Register with [`Self::with_1q_rates_for_qubit`] / +/// [`Self::with_2q_rates_for_qubits`] for heterogeneous devices, or +/// [`Self::with_1q_rates`] / [`Self::with_2q_rates`] for homogeneous +/// models. #[derive(Debug, Clone, Default)] pub struct PerGateTypeNoise { pub rates_1q: HashMap, pub rates_2q: HashMap, + pub rates_1q_per_qubit: HashMap<(GateType, QubitId), [f64; 3]>, + pub rates_2q_per_qubits: HashMap<(GateType, QubitId, QubitId), [f64; 15]>, pub p_meas: f64, pub p_init: f64, pub fallback: NoiseConfig, @@ -797,26 +807,52 @@ impl PerGateTypeNoise { Self { rates_1q: HashMap::new(), rates_2q: HashMap::new(), + rates_1q_per_qubit: HashMap::new(), + rates_2q_per_qubits: HashMap::new(), p_meas: fallback.p_meas, p_init: fallback.p_init, fallback, } } - /// Attach rates for a 1Q gate type. + /// Attach rates for a 1Q gate type applied to any qubit. #[must_use] pub fn with_1q_rates(mut self, g: GateType, rates: [f64; 3]) -> Self { self.rates_1q.insert(g, rates); self } - /// Attach rates for a 2Q gate type. + /// Attach rates for a 2Q gate type applied to any qubit pair. #[must_use] pub fn with_2q_rates(mut self, g: GateType, rates: [f64; 15]) -> Self { self.rates_2q.insert(g, rates); self } + /// Attach rates for a 1Q gate on a specific qubit. Takes precedence + /// over [`Self::with_1q_rates`] for that `(gate, qubit)` combination. + #[must_use] + pub fn with_1q_rates_for_qubit(mut self, g: GateType, q: QubitId, rates: [f64; 3]) -> Self { + self.rates_1q_per_qubit.insert((g, q), rates); + self + } + + /// Attach rates for a 2Q gate on a specific ordered qubit pair. + /// Takes precedence over [`Self::with_2q_rates`] for that + /// `(gate, q_control, q_target)` combination. + #[must_use] + pub fn with_2q_rates_for_qubits( + mut self, + g: GateType, + q_control: QubitId, + q_target: QubitId, + rates: [f64; 15], + ) -> Self { + self.rates_2q_per_qubits + .insert((g, q_control, q_target), rates); + self + } + /// Lookup 1Q Pauli rate for a gate. Returns `fallback.p1 / 3.0` if /// the gate type is not in the map. `pauli_idx` is 0=X, 1=Y, 2=Z. #[must_use] @@ -827,6 +863,17 @@ impl PerGateTypeNoise { .unwrap_or(self.fallback.p1 / 3.0) } + /// Lookup 1Q Pauli rate for a gate on a specific qubit. Tries the + /// per-qubit map first, falls back to per-gate-type, then to + /// `fallback.p1 / 3.0`. `pauli_idx` is 0=X, 1=Y, 2=Z. + #[must_use] + pub fn rate_1q_on(&self, gate: GateType, qubit: QubitId, pauli_idx: usize) -> f64 { + if let Some(rates) = self.rates_1q_per_qubit.get(&(gate, qubit)) { + return rates[pauli_idx]; + } + self.rate_1q(gate, pauli_idx) + } + /// Lookup 2Q Pauli pair rate for a gate. Returns `fallback.p2 / 15.0` /// if the gate type is not in the map. `pair_idx` follows [`PAULI_2Q_ORDER`]. #[must_use] @@ -836,6 +883,23 @@ impl PerGateTypeNoise { .map(|r| r[pair_idx]) .unwrap_or(self.fallback.p2 / 15.0) } + + /// Lookup 2Q Pauli pair rate for a gate on a specific ordered + /// qubit pair. Tries `(gate, q_control, q_target)` in the per-qubits + /// map first, falls back to per-gate-type, then to `fallback.p2/15.0`. + #[must_use] + pub fn rate_2q_on( + &self, + gate: GateType, + q_control: QubitId, + q_target: QubitId, + pair_idx: usize, + ) -> f64 { + if let Some(rates) = self.rates_2q_per_qubits.get(&(gate, q_control, q_target)) { + return rates[pair_idx]; + } + self.rate_2q(gate, pair_idx) + } } // ============================================================================ diff --git a/crates/pecos-qec/tests/per_qubit_noise_tests.rs b/crates/pecos-qec/tests/per_qubit_noise_tests.rs new file mode 100644 index 000000000..b843eac4c --- /dev/null +++ b/crates/pecos-qec/tests/per_qubit_noise_tests.rs @@ -0,0 +1,152 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Integration tests for per-qubit noise variation on top of +//! [`PerGateTypeNoise`]. Verifies: +//! +//! 1. per-qubit rates override per-gate-type defaults for matching qubits. +//! 2. qubits not in the per-qubit map fall back to per-gate-type. +//! 3. lookup lookup methods (`rate_1q_on`, `rate_2q_on`) layer correctly. + +use pecos_core::QubitId; +use pecos_qec::fault_tolerance::dem_builder::{ + DemSamplerBuilder, NoiseConfig, PerGateTypeNoise, +}; +use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; +use pecos_quantum::{DagCircuit, GateType}; + +#[test] +fn per_qubit_override_takes_precedence_over_per_gate_type() { + // Direct unit test of the lookup layering, independent of DemSampler. + let q0 = QubitId::from(0usize); + let q1 = QubitId::from(1usize); + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::uniform(0.1)) + .with_1q_rates(GateType::H, [0.01, 0.02, 0.03]) + .with_1q_rates_for_qubit(GateType::H, q0, [0.001, 0.002, 0.003]); + + // qubit 0 has per-qubit override + assert_eq!(cfg.rate_1q_on(GateType::H, q0, 0), 0.001); + assert_eq!(cfg.rate_1q_on(GateType::H, q0, 1), 0.002); + assert_eq!(cfg.rate_1q_on(GateType::H, q0, 2), 0.003); + + // qubit 1 falls back to per-gate-type + assert_eq!(cfg.rate_1q_on(GateType::H, q1, 0), 0.01); + assert_eq!(cfg.rate_1q_on(GateType::H, q1, 1), 0.02); + + // Unregistered gate on qubit 0 falls back to per-gate-type (not set), + // then to uniform fallback.p1/3. + let uniform_share = 0.1_f64 / 3.0; + assert!((cfg.rate_1q_on(GateType::X, q0, 0) - uniform_share).abs() < 1e-14); +} + +#[test] +fn per_qubit_2q_override_takes_precedence() { + let q0 = QubitId::from(0usize); + let q1 = QubitId::from(1usize); + let q2 = QubitId::from(2usize); + let q3 = QubitId::from(3usize); + + let mut per_pair = [0.0; 15]; + per_pair[0] = 1e-3; // IX + let mut gate_default = [0.0; 15]; + gate_default[0] = 5e-4; // IX + + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::uniform(0.0)) + .with_2q_rates(GateType::CX, gate_default) + .with_2q_rates_for_qubits(GateType::CX, q0, q1, per_pair); + + // (q0, q1) uses the specific rates + assert_eq!(cfg.rate_2q_on(GateType::CX, q0, q1, 0), 1e-3); + // (q2, q3) falls back to per-gate-type + assert_eq!(cfg.rate_2q_on(GateType::CX, q2, q3, 0), 5e-4); + // Different ordered pair (q1, q0): NOT the same as (q0, q1). Falls back. + assert_eq!(cfg.rate_2q_on(GateType::CX, q1, q0, 0), 5e-4); +} + +fn build_circuit_with_two_cxs() -> DagCircuit { + // Two CX gates on different qubit pairs. The per-qubit override + // should apply only to the first CX. + let mut dag = DagCircuit::new(); + dag.pz(&[4]); + dag.cx(&[(0, 4)]); + dag.cx(&[(1, 4)]); + dag.mz(&[4]); + dag +} + +#[test] +fn per_qubit_cx_rate_affects_mechanism_probabilities() { + // Two CX locations touching different qubit pairs: + // CX on (0, 4): per-qubit rate (10x baseline) + // CX on (1, 4): per-gate-type fallback rate + // Total aggregated error probability should reflect the override. + let dag = build_circuit_with_two_cxs(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let q0 = QubitId::from(0usize); + let q4 = QubitId::from(4usize); + + let baseline_rates = [1e-4; 15]; + let boosted_rates = [1e-3; 15]; + + // Control case: just the baseline. + let baseline_cfg = PerGateTypeNoise::from_fallback(NoiseConfig::uniform(0.0)) + .with_2q_rates(GateType::CX, baseline_rates); + let baseline = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(baseline_cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + // Override case: boost the (0, 4) pair specifically. + let override_cfg = PerGateTypeNoise::from_fallback(NoiseConfig::uniform(0.0)) + .with_2q_rates(GateType::CX, baseline_rates) + .with_2q_rates_for_qubits(GateType::CX, q0, q4, boosted_rates); + let overridden = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(override_cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + assert_eq!(baseline.num_mechanisms(), overridden.num_mechanisms()); + // Override should substantially raise average error probability + // (one of two CX contributions now 10x the baseline). + let avg_base = baseline.average_error_probability(); + let avg_over = overridden.average_error_probability(); + assert!( + avg_over > 2.0 * avg_base, + "expected per-qubit override to raise avg error >>2x, got base={} over={}", + avg_base, + avg_over, + ); +} + +#[test] +fn per_qubit_path_is_backward_compatible_with_per_gate_only() { + // A config with only per-gate-type rates (no per-qubit overrides) + // should produce identical output to the pre-per-qubit path. + let dag = build_circuit_with_two_cxs(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::uniform(0.0)) + .with_2q_rates(GateType::CX, [1e-3; 15]); + let sim = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + assert!(sim.num_mechanisms() > 0); + assert!(sim.average_error_probability() > 0.0); +} From 7613a0bf6f95cd80df79811320c24e16765234ed Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Wed, 15 Apr 2026 10:07:30 -0600 Subject: [PATCH 043/125] Per-qubit measurement and prep rates in PerGateTypeNoise --- .../dem_builder/dem_sampler.rs | 71 ++++++-- .../src/fault_tolerance/dem_builder/types.rs | 40 +++++ .../tests/per_qubit_measurement_tests.rs | 167 ++++++++++++++++++ 3 files changed, 260 insertions(+), 18 deletions(-) create mode 100644 crates/pecos-qec/tests/per_qubit_measurement_tests.rs diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index 83c8655d1..9b0d81620 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -1479,28 +1479,34 @@ impl<'a> DemSamplerBuilder<'a> { match loc.gate_type { GateType::PZ | GateType::QAlloc => { // Prep errors: only "after" locations (X error for Z-basis prep) - if self.p_init > 0.0 && !loc.before { - self.process_single_pauli_fault( - loc_idx, - Pauli::X, - self.p_init, - im_to_tc.as_deref(), - num_tc_measurements, - &mut aggregated, - ); + if !loc.before { + let p = self.init_rate_for_location(loc); + if p > 0.0 { + self.process_single_pauli_fault( + loc_idx, + Pauli::X, + p, + im_to_tc.as_deref(), + num_tc_measurements, + &mut aggregated, + ); + } } } GateType::MZ | GateType::MeasureFree => { // Measurement errors: only "before" locations (X error = bit flip) - if self.p_meas > 0.0 && loc.before { - self.process_single_pauli_fault( - loc_idx, - Pauli::X, - self.p_meas, - im_to_tc.as_deref(), - num_tc_measurements, - &mut aggregated, - ); + if loc.before { + let p = self.measurement_rate_for_location(loc); + if p > 0.0 { + self.process_single_pauli_fault( + loc_idx, + Pauli::X, + p, + im_to_tc.as_deref(), + num_tc_measurements, + &mut aggregated, + ); + } } } GateType::CX | GateType::CZ | GateType::CY | GateType::SWAP => { @@ -1675,6 +1681,35 @@ impl<'a> DemSamplerBuilder<'a> { } } + /// Resolve the X-error rate for a prep location. Uses `per_gate`'s + /// per-qubit `init_rates` if set, otherwise the scalar `self.p_init`. + fn init_rate_for_location( + &self, + loc: &super::super::propagator::dag::DagSpacetimeLocation, + ) -> f64 { + if let Some(pg) = &self.per_gate { + if let Some(q) = loc.qubits.first() { + return pg.init_rate_on(*q); + } + } + self.p_init + } + + /// Resolve the X-flip rate for a measurement location. Uses + /// `per_gate`'s per-qubit `measurement_rates` if set, otherwise the + /// scalar `self.p_meas`. + fn measurement_rate_for_location( + &self, + loc: &super::super::propagator::dag::DagSpacetimeLocation, + ) -> f64 { + if let Some(pg) = &self.per_gate { + if let Some(q) = loc.qubits.first() { + return pg.measurement_rate_on(*q); + } + } + self.p_meas + } + /// Resolve per-Pauli rates for a 1Q gate on a specific qubit. Uses /// `per_gate`'s per-qubit map if set, falling back to per-gate-type, /// then uniform `p1 / 3`. diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs index bb13970c0..6e31f9e47 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs @@ -795,6 +795,12 @@ pub struct PerGateTypeNoise { pub rates_2q: HashMap, pub rates_1q_per_qubit: HashMap<(GateType, QubitId), [f64; 3]>, pub rates_2q_per_qubits: HashMap<(GateType, QubitId, QubitId), [f64; 15]>, + /// Per-qubit readout (MZ) X-flip probabilities. Lookup falls back to + /// [`Self::p_meas`] for qubits not in the map. + pub measurement_rates: HashMap, + /// Per-qubit preparation (PZ) X-error probabilities. Lookup falls + /// back to [`Self::p_init`] for qubits not in the map. + pub init_rates: HashMap, pub p_meas: f64, pub p_init: f64, pub fallback: NoiseConfig, @@ -809,12 +815,46 @@ impl PerGateTypeNoise { rates_2q: HashMap::new(), rates_1q_per_qubit: HashMap::new(), rates_2q_per_qubits: HashMap::new(), + measurement_rates: HashMap::new(), + init_rates: HashMap::new(), p_meas: fallback.p_meas, p_init: fallback.p_init, fallback, } } + /// Attach measurement X-flip probability for a specific qubit. + /// Overrides [`Self::p_meas`] when set. Use for devices with + /// heterogeneous readout fidelity. + #[must_use] + pub fn with_measurement_rate(mut self, q: QubitId, p: f64) -> Self { + self.measurement_rates.insert(q, p); + self + } + + /// Attach preparation X-error probability for a specific qubit. + /// Overrides [`Self::p_init`] when set. + #[must_use] + pub fn with_init_rate(mut self, q: QubitId, p: f64) -> Self { + self.init_rates.insert(q, p); + self + } + + /// Lookup measurement X-flip rate for a qubit. Falls back to + /// [`Self::p_meas`] (which is itself seeded from the fallback + /// `NoiseConfig::p_meas`). + #[must_use] + pub fn measurement_rate_on(&self, q: QubitId) -> f64 { + *self.measurement_rates.get(&q).unwrap_or(&self.p_meas) + } + + /// Lookup preparation X-error rate for a qubit. Falls back to + /// [`Self::p_init`]. + #[must_use] + pub fn init_rate_on(&self, q: QubitId) -> f64 { + *self.init_rates.get(&q).unwrap_or(&self.p_init) + } + /// Attach rates for a 1Q gate type applied to any qubit. #[must_use] pub fn with_1q_rates(mut self, g: GateType, rates: [f64; 3]) -> Self { diff --git a/crates/pecos-qec/tests/per_qubit_measurement_tests.rs b/crates/pecos-qec/tests/per_qubit_measurement_tests.rs new file mode 100644 index 000000000..3035c25b4 --- /dev/null +++ b/crates/pecos-qec/tests/per_qubit_measurement_tests.rs @@ -0,0 +1,167 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Integration tests for per-qubit measurement and preparation rates on +//! [`PerGateTypeNoise`]. Mirrors the per-qubit gate tests but for MZ/PZ +//! locations. + +use pecos_core::QubitId; +use pecos_qec::fault_tolerance::dem_builder::{ + DemSamplerBuilder, NoiseConfig, PerGateTypeNoise, +}; +use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; +use pecos_quantum::DagCircuit; + +#[test] +fn per_qubit_measurement_override_takes_precedence() { + // Unit test the lookup layering. + let q0 = QubitId::from(0usize); + let q1 = QubitId::from(1usize); + let mut cfg = PerGateTypeNoise::from_fallback(NoiseConfig::uniform(0.01)); + // Explicitly override q0, leave q1 on the scalar fallback. + cfg = cfg.with_measurement_rate(q0, 0.1); + assert!((cfg.measurement_rate_on(q0) - 0.1).abs() < 1e-14); + assert!((cfg.measurement_rate_on(q1) - 0.01).abs() < 1e-14); +} + +#[test] +fn per_qubit_init_override_takes_precedence() { + let q0 = QubitId::from(0usize); + let q1 = QubitId::from(1usize); + let mut cfg = PerGateTypeNoise::from_fallback(NoiseConfig::uniform(0.02)); + cfg = cfg.with_init_rate(q0, 0.2); + assert!((cfg.init_rate_on(q0) - 0.2).abs() < 1e-14); + assert!((cfg.init_rate_on(q1) - 0.02).abs() < 1e-14); +} + +fn build_three_ancilla_circuit() -> DagCircuit { + // Three prep + measure operations on three different qubits. Each + // qubit is only touched once so per-qubit rates affect exactly one + // mechanism each. + let mut dag = DagCircuit::new(); + dag.pz(&[0]); + dag.pz(&[1]); + dag.pz(&[2]); + dag.mz(&[0]); + dag.mz(&[1]); + dag.mz(&[2]); + dag +} + +#[test] +fn per_qubit_measurement_rate_raises_only_targeted_qubit() { + // With per-qubit override on qubit 0, and scalar 0 for everyone else, + // the total mechanism probability should reflect only the q0 + // contribution. + let dag = build_three_ancilla_circuit(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let q0 = QubitId::from(0usize); + let cfg_only_q0 = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.0, 0.0, 0.0, 0.0)) + .with_measurement_rate(q0, 0.05); + let sim_only_q0 = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg_only_q0) + .with_detectors_json(r#"[{"id": 0, "records": [-3]}, {"id": 1, "records": [-2]}, {"id": 2, "records": [-1]}]"#) + .unwrap() + .build(); + + // Baseline: all three qubits at the same rate. + let cfg_uniform = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.0, 0.0, 0.05, 0.0)); + let sim_uniform = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg_uniform) + .with_detectors_json(r#"[{"id": 0, "records": [-3]}, {"id": 1, "records": [-2]}, {"id": 2, "records": [-1]}]"#) + .unwrap() + .build(); + + // Only q0 has meas noise in `sim_only_q0` => one mechanism. + // Uniform has meas noise on all three => three mechanisms. + // `average_error_probability` is per-mechanism, so it's the same + // in both; what differs is the count. + assert_eq!( + sim_only_q0.num_mechanisms(), + 1, + "expected exactly one mechanism for per-qubit q0-only override", + ); + assert_eq!( + sim_uniform.num_mechanisms(), + 3, + "expected three mechanisms when all qubits share the rate", + ); + // Per-mechanism probability should be the same 0.05 in both cases. + let delta = (sim_only_q0.average_error_probability() + - sim_uniform.average_error_probability()) + .abs(); + assert!(delta < 1e-12, "per-mech probabilities should match: {}", delta); +} + +#[test] +fn per_qubit_init_rate_raises_only_targeted_qubit() { + let dag = build_three_ancilla_circuit(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let q1 = QubitId::from(1usize); + let cfg_only_q1 = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.0, 0.0, 0.0, 0.0)) + .with_init_rate(q1, 0.05); + let sim_only_q1 = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg_only_q1) + .with_detectors_json(r#"[{"id": 0, "records": [-3]}, {"id": 1, "records": [-2]}, {"id": 2, "records": [-1]}]"#) + .unwrap() + .build(); + + let cfg_uniform = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.0, 0.0, 0.0, 0.05)); + let sim_uniform = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg_uniform) + .with_detectors_json(r#"[{"id": 0, "records": [-3]}, {"id": 1, "records": [-2]}, {"id": 2, "records": [-1]}]"#) + .unwrap() + .build(); + + assert_eq!( + sim_only_q1.num_mechanisms(), + 1, + "expected exactly one mechanism for per-qubit q1-only init override", + ); + assert_eq!( + sim_uniform.num_mechanisms(), + 3, + "expected three mechanisms when all qubits share the rate", + ); +} + +#[test] +fn per_qubit_measurement_path_is_backward_compatible() { + // A PerGateTypeNoise without any per-qubit measurement rates should + // fall back to scalar p_meas exactly. + let dag = build_three_ancilla_circuit(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::uniform(0.05)); + let sim_per_gate = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-3]}, {"id": 1, "records": [-2]}, {"id": 2, "records": [-1]}]"#) + .unwrap() + .build(); + + let sim_scalar = DemSamplerBuilder::new(&influence) + .with_noise(0.05, 0.05, 0.05, 0.05) + .with_detectors_json(r#"[{"id": 0, "records": [-3]}, {"id": 1, "records": [-2]}, {"id": 2, "records": [-1]}]"#) + .unwrap() + .build(); + + assert_eq!(sim_per_gate.num_mechanisms(), sim_scalar.num_mechanisms()); + let delta = (sim_per_gate.average_error_probability() + - sim_scalar.average_error_probability()) + .abs(); + assert!(delta < 1e-12, "delta {} should be near zero", delta); +} From 232368634e969caf57b4ea87c92f1012c0a095c5 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Wed, 15 Apr 2026 10:13:54 -0600 Subject: [PATCH 044/125] Add PauliLindbladModel::explain() noise-budget inspector --- exp/pecos-lindblad/src/pauli_lindblad.rs | 60 +++++++++++++++ exp/pecos-lindblad/tests/noise_budget.rs | 94 ++++++++++++++++++++++++ 2 files changed, 154 insertions(+) create mode 100644 exp/pecos-lindblad/tests/noise_budget.rs diff --git a/exp/pecos-lindblad/src/pauli_lindblad.rs b/exp/pecos-lindblad/src/pauli_lindblad.rs index 5c838eea7..3969dca8e 100644 --- a/exp/pecos-lindblad/src/pauli_lindblad.rs +++ b/exp/pecos-lindblad/src/pauli_lindblad.rs @@ -172,6 +172,66 @@ impl PauliLindbladModel { agg.into_iter().collect() } + /// Return the top `n` Pauli terms sorted by rate (descending). + /// Ties broken by lexicographic order on the Pauli string. + pub fn top_contributors(&self, n: usize) -> Vec<(PauliString, f64)> { + let mut pairs: Vec<_> = self + .supports + .iter() + .cloned() + .zip(self.rates.iter().copied()) + .collect(); + pairs.sort_by(|a, b| { + b.1.partial_cmp(&a.1).unwrap_or(std::cmp::Ordering::Equal).then_with(|| { + a.0.0 + .iter() + .map(|p| *p as u8) + .cmp(b.0.0.iter().map(|p| *p as u8)) + }) + }); + pairs.truncate(n); + pairs + } + + /// Human-readable noise-budget table: total rate, per-weight-class + /// breakdown, and top contributors. Useful for answering "where + /// is my logical error budget going?" + /// + /// Format is stable for eyeballing; not an interchange format + /// (use `serde` for that). + pub fn explain(&self) -> String { + let total = self.total_rate(); + let n_terms = self.supports.len(); + + let mut by_weight: std::collections::BTreeMap = + std::collections::BTreeMap::new(); + for (p, r) in self.supports.iter().zip(&self.rates) { + *by_weight.entry(p.weight()).or_insert(0.0) += *r; + } + + let mut out = String::new(); + out.push_str(&format!( + "Pauli-Lindblad noise budget ({} terms, total rate = {:.3e})\n", + n_terms, total, + )); + out.push_str(&"=".repeat(60)); + out.push('\n'); + out.push_str("By weight:\n"); + for (w, r) in &by_weight { + let pct = if total > 0.0 { 100.0 * r / total } else { 0.0 }; + out.push_str(&format!(" weight-{}: {:>11.3e} {:5.1}%\n", w, r, pct)); + } + out.push('\n'); + + let top_n = 10; + out.push_str(&format!("Top {} contributors:\n", top_n.min(n_terms))); + for (p, r) in self.top_contributors(top_n) { + let pct = if total > 0.0 { 100.0 * r / total } else { 0.0 }; + out.push_str(&format!(" {:<12} {:>11.3e} {:5.1}%\n", p.to_string(), r, pct)); + } + out + } + /// Heuristic diagnostic: given a predicted model (`self`) and a /// measured model (`other`), suggest physical sources likely missing /// from the prediction. Returns human-readable strings ordered by diff --git a/exp/pecos-lindblad/tests/noise_budget.rs b/exp/pecos-lindblad/tests/noise_budget.rs new file mode 100644 index 000000000..0b161110f --- /dev/null +++ b/exp/pecos-lindblad/tests/noise_budget.rs @@ -0,0 +1,94 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Tests for `PauliLindbladModel::top_contributors` / `explain`. + +use approx::assert_abs_diff_eq; + +use pecos_lindblad::{PauliLindbladModel, PauliString}; + +fn model(entries: &[(&str, f64)]) -> PauliLindbladModel { + let supports: Vec<_> = entries.iter().map(|(s, _)| PauliString::from_str(s).unwrap()).collect(); + let rates: Vec<_> = entries.iter().map(|(_, r)| *r).collect(); + PauliLindbladModel::new(supports, rates) +} + +#[test] +fn top_contributors_sorted_by_rate_descending() { + let m = model(&[("IX", 0.001), ("ZI", 0.005), ("IY", 0.003), ("IZ", 0.002)]); + let top = m.top_contributors(4); + assert_eq!(format!("{}", top[0].0), "ZI"); // 0.005 + assert_eq!(format!("{}", top[1].0), "IY"); // 0.003 + assert_eq!(format!("{}", top[2].0), "IZ"); // 0.002 + assert_eq!(format!("{}", top[3].0), "IX"); // 0.001 +} + +#[test] +fn top_contributors_truncates_to_n() { + let m = model(&[("X", 0.01), ("Y", 0.02), ("Z", 0.03)]); + let top2 = m.top_contributors(2); + assert_eq!(top2.len(), 2); + assert_eq!(format!("{}", top2[0].0), "Z"); + assert_eq!(format!("{}", top2[1].0), "Y"); +} + +#[test] +fn top_contributors_ties_broken_lexicographically() { + let m = model(&[("X", 0.01), ("Y", 0.01), ("Z", 0.01)]); + let top = m.top_contributors(3); + // Tie on rate -> lexicographic on Pauli1 (I Date: Wed, 15 Apr 2026 10:17:19 -0600 Subject: [PATCH 045/125] Route GateType::Idle locations through 1Q noise path --- .../dem_builder/dem_sampler.rs | 6 +- crates/pecos-qec/tests/idle_noise_tests.rs | 130 ++++++++++++++++++ 2 files changed, 135 insertions(+), 1 deletion(-) create mode 100644 crates/pecos-qec/tests/idle_noise_tests.rs diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index 9b0d81620..e3a23e943 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -1524,8 +1524,12 @@ impl<'a> DemSamplerBuilder<'a> { | GateType::SYdg | GateType::X | GateType::Y - | GateType::Z => { + | GateType::Z + | GateType::Idle => { // Single-qubit gate errors: only "after" locations. + // Idle locations use the per-qubit lookup so users can + // say "qubit 3's idle noise is different from qubit 5's" + // via `.with_1q_rates_for_qubit(GateType::Idle, q, rates)`. if !loc.before { let rates = self.rates_1q(loc.gate_type, &loc.qubits); if rates.iter().any(|r| *r > 0.0) { diff --git a/crates/pecos-qec/tests/idle_noise_tests.rs b/crates/pecos-qec/tests/idle_noise_tests.rs new file mode 100644 index 000000000..5ea4007f2 --- /dev/null +++ b/crates/pecos-qec/tests/idle_noise_tests.rs @@ -0,0 +1,130 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Integration tests for idle-gate noise. In QEC circuits, ancilla +//! qubits often sit idle while 2Q gates run on others. Before this test, +//! `GateType::Idle` locations were silently dropped from the DEM (they +//! fell through the default arm in `build()`). These tests verify idle +//! qubits now contribute per-qubit per-Pauli rates. + +use pecos_core::{QubitId, TimeUnits}; +use pecos_qec::fault_tolerance::dem_builder::{ + DemSamplerBuilder, NoiseConfig, PerGateTypeNoise, +}; +use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; +use pecos_quantum::{DagCircuit, GateType}; + +fn build_idle_then_measure(num_idles: usize) -> DagCircuit { + // Prep N qubits, idle each once, measure each. Very simple fixture + // to isolate idle-gate contributions. + let mut dag = DagCircuit::new(); + for q in 0..num_idles { + dag.pz(&[q]); + } + for q in 0..num_idles { + dag.idle(TimeUnits::new(100), &[q]); + } + for q in 0..num_idles { + dag.mz(&[q]); + } + dag +} + +#[test] +fn idle_locations_contribute_mechanisms_when_rates_set() { + let dag = build_idle_then_measure(2); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + // No noise elsewhere; idle rates set only on qubit 0. + let q0 = QubitId::from(0usize); + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.0, 0.0, 0.0, 0.0)) + .with_1q_rates_for_qubit(GateType::Idle, q0, [0.001, 0.001, 0.001]); + let sim = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-2]}, {"id": 1, "records": [-1]}]"#) + .unwrap() + .build(); + + // Exactly one location contributes noise (idle on q0). That location + // produces X, Y, Z mechanisms, of which X+Y generally both flip the + // Z-basis measurement, but aggregation collapses them. Expect at + // least one mechanism -> we used to get zero silently. + assert!( + sim.num_mechanisms() > 0, + "idle on q0 should produce at least one mechanism", + ); +} + +#[test] +fn idle_rates_absent_means_no_idle_contribution() { + // Config provides no Idle rates and uses zero fallback. DEM should + // have zero mechanisms: prep/measure are 0 and idle falls back to + // the per-gate-type default ([p1/3]), which is 0 here. + let dag = build_idle_then_measure(3); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.0, 0.0, 0.0, 0.0)); + let sim = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-3]}, {"id": 1, "records": [-2]}, {"id": 2, "records": [-1]}]"#) + .unwrap() + .build(); + assert_eq!(sim.num_mechanisms(), 0); +} + +#[test] +fn idle_noise_respects_per_qubit_override() { + // q0 gets boosted idle rate; q1 gets zero. Expect exactly one + // mechanism from q0's idle. + let dag = build_idle_then_measure(2); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let q0 = QubitId::from(0usize); + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.0, 0.0, 0.0, 0.0)) + .with_1q_rates(GateType::Idle, [0.0, 0.0, 0.0]) + .with_1q_rates_for_qubit(GateType::Idle, q0, [0.01, 0.01, 0.01]); + let sim = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-2]}, {"id": 1, "records": [-1]}]"#) + .unwrap() + .build(); + + assert!(sim.num_mechanisms() > 0); + // q1's idle at zero rates should not contribute -- only q0's. + assert!(sim.max_error_probability() >= 0.01 * 0.5); +} + +#[test] +fn idle_with_scalar_uniform_still_noisy() { + // Legacy uniform-depolarizing path: p1 = 0.01 applied uniformly. + // Idle locations should now ALSO pick up this rate (they used to + // be silent). Ensure the legacy path isn't regressed. + let dag = build_idle_then_measure(2); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let sim = DemSamplerBuilder::new(&influence) + .with_noise(0.01, 0.0, 0.0, 0.0) + .with_detectors_json(r#"[{"id": 0, "records": [-2]}, {"id": 1, "records": [-1]}]"#) + .unwrap() + .build(); + + // Before fix: zero mechanisms (idle ignored). After fix: idle on + // both qubits contributes. + assert!( + sim.num_mechanisms() > 0, + "scalar p1 path should propagate through idle locations too", + ); +} From 98c2ff34227589ad0efb0f5be5f52421eef056e7 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Wed, 15 Apr 2026 10:36:17 -0600 Subject: [PATCH 046/125] DemStabSim::detector_error_model() for Stim-format DEM text export --- crates/pecos-qec/src/dem_stab.rs | 31 ++++- .../dem_builder/dem_sampler.rs | 32 +++++ .../pecos-qec/tests/stim_dem_export_tests.rs | 128 ++++++++++++++++++ 3 files changed, 190 insertions(+), 1 deletion(-) create mode 100644 crates/pecos-qec/tests/stim_dem_export_tests.rs diff --git a/crates/pecos-qec/src/dem_stab.rs b/crates/pecos-qec/src/dem_stab.rs index 10a4d23ae..3899a3dba 100644 --- a/crates/pecos-qec/src/dem_stab.rs +++ b/crates/pecos-qec/src/dem_stab.rs @@ -51,7 +51,8 @@ //! ``` use crate::fault_tolerance::dem_builder::{ - DemSampler, DemSamplerBuilder, DetectorDef, LogicalObservable, NoiseConfig, PerGateTypeNoise, + DemSampler, DemSamplerBuilder, DetectorDef, DetectorErrorModel, LogicalObservable, NoiseConfig, + PerGateTypeNoise, }; use crate::fault_tolerance::propagator::DagFaultAnalyzer; use pecos_quantum::DagCircuit; @@ -87,6 +88,10 @@ pub struct DemStabShotBatch { #[derive(Debug, Clone)] pub struct DemStabSim { sampler: DemSampler, + /// Detector definitions preserved from the builder, used to produce + /// a text-serializable [`DetectorErrorModel`] with full metadata. + detectors: Vec, + observables: Vec, } impl DemStabSim { @@ -120,6 +125,25 @@ impl DemStabSim { &self.sampler } + /// Produce a [`DetectorErrorModel`] reflecting the compiled mechanism + /// set and the detector / observable definitions the builder was + /// given. Use [`DetectorErrorModel::to_string`] for Stim-compatible + /// text output. + /// + /// Note: the probabilities are recovered from the sampler's stored + /// `u64` thresholds, which round-trips to ~machine precision. + #[must_use] + pub fn detector_error_model(&self) -> DetectorErrorModel { + let mut dem = self.sampler.to_detector_error_model(); + for det in &self.detectors { + dem.add_detector(det.clone()); + } + for obs in &self.observables { + dem.add_observable(obs.clone()); + } + dem + } + /// Sample `num_shots` independent shots from the compiled DEM. #[must_use] pub fn sample_batch(&self, num_shots: usize, rng: &mut R) -> DemStabShotBatch { @@ -228,8 +252,13 @@ impl DemStabSimBuilder { builder = builder.with_measurement_order(order); } + let detectors = self.detectors.clone(); + let observables = self.observables.clone(); + Ok(DemStabSim { sampler: builder.build(), + detectors, + observables, }) } } diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index a390b4033..0608836f6 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -237,6 +237,38 @@ impl DemSampler { self.num_observables } + /// Reconstruct a [`DetectorErrorModel`] from the aggregated SoA + /// mechanism state for text output (e.g. Stim-format via + /// [`DetectorErrorModel::to_string`]). + /// + /// Each stored mechanism becomes a `direct` contribution with its + /// approximate probability (recovered from the `u64` threshold). + /// Detector / observable declarations are NOT emitted -- those + /// require the original `DetectorDef` / `LogicalObservable` + /// definitions held by higher-level wrappers such as + /// [`crate::dem_stab::DemStabSim`]. Callers who need full metadata + /// should populate those on the returned DEM. + #[must_use] + pub fn to_detector_error_model(&self) -> super::types::DetectorErrorModel { + use super::types::{DetectorErrorModel, FaultMechanism}; + let mut dem = + DetectorErrorModel::with_capacity(self.num_detectors, self.num_observables); + let inv_max = 1.0_f64 / u64::MAX as f64; + for i in 0..self.thresholds.len() { + let prob = self.thresholds[i] as f64 * inv_max; + let det_start = self.detector_offsets[i] as usize; + let det_end = self.detector_offsets[i + 1] as usize; + let obs_start = self.observable_offsets[i] as usize; + let obs_end = self.observable_offsets[i + 1] as usize; + let mechanism = FaultMechanism::from_unsorted( + self.detector_data[det_start..det_end].iter().copied(), + self.observable_data[obs_start..obs_end].iter().copied(), + ); + dem.add_direct_contribution(mechanism, prob); + } + dem + } + /// Create a [`DemSampler`] from raw mechanism data. /// /// This constructor is used when building from a parsed DEM string rather than diff --git a/crates/pecos-qec/tests/stim_dem_export_tests.rs b/crates/pecos-qec/tests/stim_dem_export_tests.rs new file mode 100644 index 000000000..b869e4e0d --- /dev/null +++ b/crates/pecos-qec/tests/stim_dem_export_tests.rs @@ -0,0 +1,128 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Integration tests for Stim-format DEM export from `DemStabSim` with +//! per-gate noise. Closes the +//! `~/Repos/pecos-docs/ideas/stim-compat-dem-export.md` gap. + +use pecos_core::QubitId; +use pecos_qec::dem_stab::DemStabSim; +use pecos_qec::fault_tolerance::dem_builder::{ + DetectorDef, LogicalObservable, NoiseConfig, PerGateTypeNoise, +}; +use pecos_quantum::{DagCircuit, GateType}; + +fn build_parity_check() -> DagCircuit { + let mut dag = DagCircuit::new(); + dag.pz(&[2]); + dag.cx(&[(0, 2)]); + dag.cx(&[(1, 2)]); + dag.mz(&[2]); + dag +} + +#[test] +fn dem_text_export_with_scalar_noise() { + let dag = build_parity_check(); + let sim = DemStabSim::builder() + .circuit(dag) + .noise(NoiseConfig::uniform(0.01)) + .detectors(vec![DetectorDef::new(0).with_records([-1])]) + .observables(vec![LogicalObservable::new(0).with_records([-1])]) + .build() + .unwrap(); + + let dem = sim.detector_error_model(); + let text = dem.to_string(); + + // Must contain at least one error mechanism. + assert!(text.contains("error("), "expected 'error(' line in DEM text:\n{}", text); + // Must declare the detector and observable. + assert!(text.contains("detector D0"), "missing detector D0:\n{}", text); + assert!( + text.contains("logical_observable L0") || text.contains("observable_include L0"), + "missing observable decl:\n{}", + text, + ); +} + +#[test] +fn dem_text_export_with_per_gate_noise() { + let dag = build_parity_check(); + let q0 = QubitId::from(0usize); + let q2 = QubitId::from(2usize); + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.0, 0.0, 0.001, 0.001)) + .with_2q_rates(GateType::CX, [1e-3; 15]) + .with_2q_rates_for_qubits(GateType::CX, q0, q2, [5e-3; 15]); + let sim = DemStabSim::builder() + .circuit(dag) + .per_gate_noise(cfg) + .detectors(vec![DetectorDef::new(0).with_records([-1])]) + .build() + .unwrap(); + + let dem = sim.detector_error_model(); + let text = dem.to_string(); + + // Should render multiple error mechanisms (CX on (0,2) boosted vs CX on (1,2)). + let error_lines = text.matches("error(").count(); + assert!( + error_lines > 0, + "expected per-gate-noise path to produce error lines:\n{}", + text, + ); + assert!(text.contains("detector D0")); +} + +#[test] +fn dem_round_trip_mechanism_count_matches_sampler() { + let dag = build_parity_check(); + let sim = DemStabSim::builder() + .circuit(dag) + .noise(NoiseConfig::uniform(0.005)) + .detectors(vec![DetectorDef::new(0).with_records([-1])]) + .build() + .unwrap(); + + let dem = sim.detector_error_model(); + // The reconstructed DEM should have the same mechanism count as the + // sampler (direct contributions). + assert_eq!( + dem.num_contributions(), + sim.num_mechanisms(), + "mechanism count should round-trip between sampler and reconstructed DEM" + ); +} + +#[test] +fn dem_probabilities_recoverable_from_thresholds() { + // Check that the prob → u64 threshold → prob round-trip is close. + // Use a small, well-separated set of mechanisms. + let dag = build_parity_check(); + let sim = DemStabSim::builder() + .circuit(dag) + .noise(NoiseConfig::uniform(0.01)) + .detectors(vec![DetectorDef::new(0).with_records([-1])]) + .build() + .unwrap(); + + let dem = sim.detector_error_model(); + let text = dem.to_string(); + // Probabilities recovered should be non-zero and appear in the text + // in some form. + for line in text.lines().filter(|l| l.starts_with("error(")) { + // Parse the prob inside "error(...)". + let inner = line.trim_start_matches("error(").split(')').next().unwrap(); + let p: f64 = inner.parse().unwrap(); + assert!(p > 0.0 && p < 1.0, "probability out of range: {}", p); + } +} From 0ff128cfbc865e8edbd460a6225f0882cb09595a Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Wed, 15 Apr 2026 10:44:46 -0600 Subject: [PATCH 047/125] DemBuilder::with_per_gate_noise for decomposed DEM text with asymmetric noise Teach the DEM text-output pipeline (DemBuilder) the same per-gate-type per-qubit per-Pauli noise spec that DemSamplerBuilder uses. Unblocks decomposed/MWPM-friendly DEM export from asymmetric device noise. Refactored 4 process_*_source_tracked functions to consume rate lookups instead of scalar noise.p*. Added helpers mirroring DemSamplerBuilder: init_rate_for_loc, measurement_rate_for_loc, rates_1q_for_loc, rates_2q_for_locs. Layered lookup: (gate, qubit/pair) -> (gate) -> uniform. Also routed GateType::Idle through the 1Q match arm (parity with DemSamplerBuilder fix). Scalar path preserved exactly: rates_1q/2q helpers use the existing per_channel_probability formula when no per-gate spec is set. 473 prior pecos-qec tests stay green; 5 new per-gate DEM tests green. --- .../fault_tolerance/dem_builder/builder.rs | 161 +++++++++++--- .../tests/per_gate_dem_builder_tests.rs | 197 ++++++++++++++++++ 2 files changed, 327 insertions(+), 31 deletions(-) create mode 100644 crates/pecos-qec/tests/per_gate_dem_builder_tests.rs diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs index c75e17256..2d2883e79 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs @@ -17,8 +17,9 @@ use super::types::{ DetectorDef, DetectorErrorModel, DirectSourceComponents, FaultMechanism, LogicalObservable, - NoiseConfig, SourceMetadata, record_offset_to_absolute_index, + NoiseConfig, PerGateTypeNoise, SourceMetadata, record_offset_to_absolute_index, }; +use crate::fault_tolerance::propagator::dag::DagSpacetimeLocation; use crate::fault_tolerance::propagator::{DagFaultInfluenceMap, Pauli}; use pecos_core::gate_type::GateType; use smallvec::SmallVec; @@ -80,8 +81,14 @@ struct ParsedObservable { pub struct DemBuilder<'a> { /// Reference to the fault influence map. influence_map: &'a DagFaultInfluenceMap, - /// Noise configuration. + /// Uniform-depolarizing noise configuration. When `per_gate` is also + /// set, its per-qubit / per-Pauli overrides take precedence; this + /// `NoiseConfig` still seeds measurement/prep scalars. noise: NoiseConfig, + /// Optional per-gate-type per-Pauli noise spec. Mirrors the + /// `DemSamplerBuilder` path so DEM text export reflects the same + /// asymmetric noise structure that the sampler does. + per_gate: Option, /// Parsed detector definitions. detectors: Vec, /// Parsed observable definitions. @@ -100,6 +107,7 @@ impl<'a> DemBuilder<'a> { Self { influence_map, noise: NoiseConfig::default(), + per_gate: None, detectors: Vec::new(), observables: Vec::new(), num_measurements: influence_map.measurements.len(), @@ -107,13 +115,80 @@ impl<'a> DemBuilder<'a> { } } - /// Sets the noise configuration. + /// Sets the uniform-depolarizing noise configuration. #[must_use] pub fn with_noise(mut self, p1: f64, p2: f64, p_meas: f64, p_init: f64) -> Self { self.noise = NoiseConfig::new(p1, p2, p_meas, p_init); self } + /// Attach per-gate-type per-Pauli noise. When present, overrides + /// [`Self::with_noise`] scalars for gate types in the spec's maps. + /// Mirrors + /// [`crate::fault_tolerance::dem_builder::DemSamplerBuilder::with_per_gate_noise`] + /// so the DEM text output reflects the same noise structure. + #[must_use] + pub fn with_per_gate_noise(mut self, cfg: PerGateTypeNoise) -> Self { + self.noise.p_meas = cfg.p_meas; + self.noise.p_init = cfg.p_init; + self.per_gate = Some(cfg); + self + } + + /// Resolve preparation X-error rate at a specific location. + fn init_rate_for_loc(&self, loc: &DagSpacetimeLocation) -> f64 { + if let Some(pg) = &self.per_gate { + if let Some(q) = loc.qubits.first() { + return pg.init_rate_on(*q); + } + } + self.noise.p_init + } + + /// Resolve measurement X-flip rate at a specific location. + fn measurement_rate_for_loc(&self, loc: &DagSpacetimeLocation) -> f64 { + if let Some(pg) = &self.per_gate { + if let Some(q) = loc.qubits.first() { + return pg.measurement_rate_on(*q); + } + } + self.noise.p_meas + } + + /// Resolve `[rate_X, rate_Y, rate_Z]` for a 1Q gate location. + fn rates_1q_for_loc(&self, loc: &DagSpacetimeLocation) -> [f64; 3] { + if let Some(pg) = &self.per_gate { + if let Some(q) = loc.qubits.first() { + return [ + pg.rate_1q_on(loc.gate_type, *q, 0), + pg.rate_1q_on(loc.gate_type, *q, 1), + pg.rate_1q_on(loc.gate_type, *q, 2), + ]; + } + return [pg.rate_1q(loc.gate_type, 0), pg.rate_1q(loc.gate_type, 1), pg.rate_1q(loc.gate_type, 2)]; + } + let per = per_channel_probability(self.noise.p1, 3); + [per, per, per] + } + + /// Resolve the 15-entry 2Q per-Pauli-pair rate array for a gate + /// spanning two fault locations. + fn rates_2q_for_locs( + &self, + loc1: &DagSpacetimeLocation, + loc2: &DagSpacetimeLocation, + ) -> [f64; 15] { + if let Some(pg) = &self.per_gate { + let gate = loc1.gate_type; + let mut qubits = loc1.qubits.iter().copied().chain(loc2.qubits.iter().copied()); + if let (Some(qc), Some(qt)) = (qubits.next(), qubits.next()) { + return std::array::from_fn(|i| pg.rate_2q_on(gate, qc, qt, i)); + } + return std::array::from_fn(|i| pg.rate_2q(gate, i)); + } + [per_channel_probability(self.noise.p2, 15); 15] + } + /// Sets the number of measurements (used for record offset calculation). #[must_use] pub fn with_num_measurements(mut self, num: usize) -> Self { @@ -236,7 +311,7 @@ impl<'a> DemBuilder<'a> { for (loc_idx, loc) in locations.iter().enumerate() { match loc.gate_type { GateType::PZ | GateType::QAlloc => { - if self.noise.p_init > 0.0 && !loc.before { + if !loc.before && self.init_rate_for_loc(loc) > 0.0 { self.process_prep_fault_source_tracked( loc_idx, dem, @@ -246,7 +321,7 @@ impl<'a> DemBuilder<'a> { } } GateType::MZ | GateType::MeasureFree => { - if self.noise.p_meas > 0.0 && loc.before { + if loc.before && self.measurement_rate_for_loc(loc) > 0.0 { self.process_meas_fault_source_tracked( loc_idx, dem, @@ -282,14 +357,19 @@ impl<'a> DemBuilder<'a> { | GateType::RY | GateType::RZ | GateType::U - | GateType::R1XY => { - if self.noise.p1 > 0.0 && !loc.before { - self.process_single_qubit_fault_source_tracked( - loc_idx, - dem, - meas_to_detectors, - meas_to_observables, - ); + | GateType::R1XY + | GateType::Idle => { + if !loc.before { + let rates = self.rates_1q_for_loc(loc); + if rates.iter().any(|r| *r > 0.0) { + self.process_single_qubit_fault_source_tracked( + loc_idx, + rates, + dem, + meas_to_detectors, + meas_to_observables, + ); + } } } _ => {} @@ -297,12 +377,16 @@ impl<'a> DemBuilder<'a> { } // Process two-qubit gates - if self.noise.p2 > 0.0 { - for (_, loc_indices) in cx_groups { - if loc_indices.len() == 2 { + for (_, loc_indices) in cx_groups { + if loc_indices.len() == 2 { + let loc1 = &locations[loc_indices[0]]; + let loc2 = &locations[loc_indices[1]]; + let rates = self.rates_2q_for_locs(loc1, loc2); + if rates.iter().any(|r| *r > 0.0) { self.process_two_qubit_fault_source_tracked( loc_indices[0], loc_indices[1], + rates, dem, meas_to_detectors, meas_to_observables, @@ -320,18 +404,20 @@ impl<'a> DemBuilder<'a> { meas_to_detectors: &BTreeMap>, meas_to_observables: &BTreeMap>, ) { + let loc = &self.influence_map.locations[loc_idx]; + let p = self.init_rate_for_loc(loc); // For Z-basis prep, X error matters - this is a direct source let mechanism = self.compute_mechanism(loc_idx, Pauli::X, meas_to_detectors, meas_to_observables); if !mechanism.is_empty() { dem.add_direct_contribution_with_source( mechanism, - self.noise.p_init, + p, SourceMetadata::new( &[loc_idx], &[Pauli::X], - &[self.influence_map.locations[loc_idx].gate_type], - &[self.influence_map.locations[loc_idx].before], + &[loc.gate_type], + &[loc.before], ), ); } @@ -345,32 +431,36 @@ impl<'a> DemBuilder<'a> { meas_to_detectors: &BTreeMap>, meas_to_observables: &BTreeMap>, ) { + let loc = &self.influence_map.locations[loc_idx]; + let p = self.measurement_rate_for_loc(loc); // Measurement error is a bit flip (X error) - this is a direct source let mechanism = self.compute_mechanism(loc_idx, Pauli::X, meas_to_detectors, meas_to_observables); if !mechanism.is_empty() { dem.add_direct_contribution_with_source( mechanism, - self.noise.p_meas, + p, SourceMetadata::new( &[loc_idx], &[Pauli::X], - &[self.influence_map.locations[loc_idx].gate_type], - &[self.influence_map.locations[loc_idx].before], + &[loc.gate_type], + &[loc.before], ), ); } } /// Processes a single-qubit gate fault with source tracking. + /// `rates` is `[rate_X, rate_Y, rate_Z]` -- zero entries are skipped. fn process_single_qubit_fault_source_tracked( &self, loc_idx: usize, + rates: [f64; 3], dem: &mut DetectorErrorModel, meas_to_detectors: &BTreeMap>, meas_to_observables: &BTreeMap>, ) { - let prob = per_channel_probability(self.noise.p1, 3); + let [rate_x, rate_y, rate_z] = rates; let x_effect = self.compute_mechanism(loc_idx, Pauli::X, meas_to_detectors, meas_to_observables); @@ -378,10 +468,10 @@ impl<'a> DemBuilder<'a> { self.compute_mechanism(loc_idx, Pauli::Z, meas_to_detectors, meas_to_observables); // X error: direct source - if !x_effect.is_empty() { + if rate_x > 0.0 && !x_effect.is_empty() { dem.add_direct_contribution_with_source( x_effect.clone(), - prob, + rate_x, SourceMetadata::new( &[loc_idx], &[Pauli::X], @@ -392,10 +482,10 @@ impl<'a> DemBuilder<'a> { } // Z error: direct source - if !z_effect.is_empty() { + if rate_z > 0.0 && !z_effect.is_empty() { dem.add_direct_contribution_with_source( z_effect.clone(), - prob, + rate_z, SourceMetadata::new( &[loc_idx], &[Pauli::Z], @@ -412,13 +502,13 @@ impl<'a> DemBuilder<'a> { // 3. X empty, Z non-empty: Y has same effect as Z (direct) // 4. Both non-empty and equal: Y effect is empty (X XOR X = nothing) let y_effect = x_effect.xor(&z_effect); - if !y_effect.is_empty() { + if rate_y > 0.0 && !y_effect.is_empty() { if !x_effect.is_empty() && !z_effect.is_empty() { // Both non-empty, so Y is decomposable as X ^ Z dem.add_y_decomposed_contribution_with_source( &x_effect, &z_effect, - prob, + rate_y, SourceMetadata::new( &[loc_idx], &[Pauli::Y], @@ -430,7 +520,7 @@ impl<'a> DemBuilder<'a> { // One is empty, so Y has same effect as the non-empty one (direct source) dem.add_direct_contribution_with_source( y_effect, - prob, + rate_y, SourceMetadata::new( &[loc_idx], &[Pauli::Y], @@ -443,15 +533,17 @@ impl<'a> DemBuilder<'a> { } /// Processes a two-qubit gate fault with source tracking and intra-channel decomposition. + /// `rates` is the 15-entry array in `PAULI_2Q_ORDER` order -- zero entries + /// are skipped. fn process_two_qubit_fault_source_tracked( &self, loc1: usize, loc2: usize, + rates: [f64; 15], dem: &mut DetectorErrorModel, meas_to_detectors: &BTreeMap>, meas_to_observables: &BTreeMap>, ) { - let prob = per_channel_probability(self.noise.p2, 15); let loc1_meta = &self.influence_map.locations[loc1]; let loc2_meta = &self.influence_map.locations[loc2]; @@ -493,6 +585,13 @@ impl<'a> DemBuilder<'a> { continue; } + // Per-pair rate: index = 4*p1 + p2 - 1 (skipping II at idx 0). + let flat = 4 * (p1 as usize) + (p2 as usize); + let prob = rates[flat - 1]; + if prob == 0.0 { + continue; + } + // Get component effects (P1I and IP2) let e1 = &effects[p1 as usize][0]; // P1 on qubit 1, I on qubit 2 let e2 = &effects[0][p2 as usize]; // I on qubit 1, P2 on qubit 2 diff --git a/crates/pecos-qec/tests/per_gate_dem_builder_tests.rs b/crates/pecos-qec/tests/per_gate_dem_builder_tests.rs new file mode 100644 index 000000000..556d9ac82 --- /dev/null +++ b/crates/pecos-qec/tests/per_gate_dem_builder_tests.rs @@ -0,0 +1,197 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Integration tests for `DemBuilder::with_per_gate_noise`. Parity with +//! `DemSamplerBuilder` path + verification that decomposed DEM text +//! output reflects per-gate-type per-Pauli rates. + +use pecos_core::{QubitId, TimeUnits}; +use pecos_qec::fault_tolerance::dem_builder::{DemBuilder, NoiseConfig, PerGateTypeNoise}; +use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; +use pecos_quantum::{DagCircuit, GateType}; + +fn build_parity_check() -> DagCircuit { + let mut dag = DagCircuit::new(); + dag.pz(&[2]); + dag.cx(&[(0, 2)]); + dag.cx(&[(1, 2)]); + dag.mz(&[2]); + dag +} + +#[test] +fn uniform_equivalent_per_gate_matches_scalar_dem() { + // DemBuilder with empty-map PerGateTypeNoise (fallback only) should + // produce the same DEM text as scalar `with_noise`. + let dag = build_parity_check(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let scalar = DemBuilder::new(&influence) + .with_noise(0.01, 0.02, 0.005, 0.003) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + let per_gate = DemBuilder::new(&influence) + .with_per_gate_noise(PerGateTypeNoise::from_fallback(NoiseConfig::new(0.01, 0.02, 0.005, 0.003))) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + // Both DEMs should contain the same mechanism set with matching probabilities. + assert_eq!(scalar.num_contributions(), per_gate.num_contributions()); + let scalar_text = scalar.to_string(); + let per_gate_text = per_gate.to_string(); + // Equal line counts in the text form (mechanism-by-mechanism identical). + assert_eq!( + scalar_text.lines().filter(|l| l.starts_with("error(")).count(), + per_gate_text.lines().filter(|l| l.starts_with("error(")).count(), + "scalar and uniform-per-gate should produce identical error-line counts:\nscalar:\n{}\nper_gate:\n{}", + scalar_text, + per_gate_text, + ); +} + +#[test] +fn per_gate_override_produces_decomposed_dem_text() { + // Specific per-gate CX rates should appear in the decomposed DEM text. + let dag = build_parity_check(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let mut rates_2q = [0.0; 15]; + // IX = index 0, nonzero probability + rates_2q[0] = 1e-3; + // XX = index 4 ("IX","IY","IZ","XI","XX",...) — high correlated rate + rates_2q[4] = 5e-3; + + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.0, 0.0, 0.0, 0.0)) + .with_2q_rates(GateType::CX, rates_2q); + + let dem = DemBuilder::new(&influence) + .with_per_gate_noise(cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + let text = dem.to_string_decomposed(); + let error_lines = text.lines().filter(|l| l.starts_with("error(")).count(); + assert!( + error_lines > 0, + "expected per-gate CX rates to produce error lines in decomposed DEM:\n{}", + text, + ); +} + +#[test] +fn per_qubit_cx_override_changes_dem_probabilities() { + // Like the sampler-path test: boost CX (0, 2) per-qubit-pair, compare + // to baseline where only per-gate-type is set. + let dag = build_parity_check(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let q0 = QubitId::from(0usize); + let q2 = QubitId::from(2usize); + + let cfg_baseline = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.0, 0.0, 0.0, 0.0)) + .with_2q_rates(GateType::CX, [1e-4; 15]); + let cfg_boost = cfg_baseline + .clone() + .with_2q_rates_for_qubits(GateType::CX, q0, q2, [1e-3; 15]); + + let baseline = DemBuilder::new(&influence) + .with_per_gate_noise(cfg_baseline) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + let boosted = DemBuilder::new(&influence) + .with_per_gate_noise(cfg_boost) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + // Both produce the same mechanism set (same circuit structure) but + // the boosted DEM should have higher-average probabilities in its text. + assert_eq!(baseline.num_contributions(), boosted.num_contributions()); + + // Parse error-line probabilities and sum them. + let sum_probs = |s: &str| -> f64 { + s.lines() + .filter_map(|l| l.strip_prefix("error(")) + .filter_map(|inner| inner.split(')').next()) + .filter_map(|p| p.parse::().ok()) + .sum() + }; + let baseline_sum = sum_probs(&baseline.to_string()); + let boosted_sum = sum_probs(&boosted.to_string()); + assert!( + boosted_sum > 2.0 * baseline_sum, + "per-qubit-pair boost should raise probability sum: baseline={} boosted={}", + baseline_sum, + boosted_sum, + ); +} + +#[test] +fn idle_locations_contribute_to_dem_text() { + // Circuit with an idle gate + per-qubit idle rate should produce an + // error line for the idle location. Before the Idle routing fix this + // test would see zero idle contributions. + let mut dag = DagCircuit::new(); + dag.pz(&[0]); + dag.idle(TimeUnits::new(100), &[0]); + dag.mz(&[0]); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let q0 = QubitId::from(0usize); + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.0, 0.0, 0.0, 0.0)) + .with_1q_rates_for_qubit(GateType::Idle, q0, [0.01, 0.01, 0.01]); + + let dem = DemBuilder::new(&influence) + .with_per_gate_noise(cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + let text = dem.to_string(); + assert!( + text.contains("error("), + "expected idle location to produce an error line:\n{}", + text, + ); +} + +#[test] +fn decomposed_dem_reflects_per_gate_noise() { + // DemBuilder's decomposed path uses mark_graphlike_decomposable and + // Y-decomposition logic. Verify the text output includes both + // direct and decomposed-effect lines when per-gate noise is set. + let dag = build_parity_check(); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let cfg = PerGateTypeNoise::from_fallback(NoiseConfig::new(0.005, 0.005, 0.005, 0.005)); + let dem = DemBuilder::new(&influence) + .with_per_gate_noise(cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + // Both formats should have content. + let non_decomposed = dem.to_string(); + let decomposed = dem.to_string_decomposed(); + assert!(non_decomposed.contains("error(")); + assert!(decomposed.contains("error(")); +} From 1caf399b09da7666e8c14d82525c28b154a1a68d Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Thu, 16 Apr 2026 18:17:11 -0600 Subject: [PATCH 048/125] Move 5 lindblad/DEM design docs to pecos-docs vault --- design/dem_stab_sim_skeleton.md | 255 -------------- design/lindblad_magnus_algorithm.md | 514 ---------------------------- design/lindblad_sim_skeleton.md | 420 ----------------------- design/qec_sim_literature.md | 484 -------------------------- design/stab_sample_orchestration.md | 267 --------------- 5 files changed, 1940 deletions(-) delete mode 100644 design/dem_stab_sim_skeleton.md delete mode 100644 design/lindblad_magnus_algorithm.md delete mode 100644 design/lindblad_sim_skeleton.md delete mode 100644 design/qec_sim_literature.md delete mode 100644 design/stab_sample_orchestration.md diff --git a/design/dem_stab_sim_skeleton.md b/design/dem_stab_sim_skeleton.md deleted file mode 100644 index b5098fb60..000000000 --- a/design/dem_stab_sim_skeleton.md +++ /dev/null @@ -1,255 +0,0 @@ -# DemStabSim Module Skeleton - -Status: partially superseded (2026-04-11). See **`design/stab_sample_orchestration.md`**. -Target crate: `pecos-qec` (pure-sim types) + TBD (engine integration deferred) -Pairs with: `design/qec_sim_literature.md`, `design/stab_sample_orchestration.md` - -## Current state - -**Superseded parts:** -- Original plan: wrap `DemStabSim` behind `sim().quantum(dem_stab())` via a `QuantumEngine` record-and-replay impl (Path A). -- Replaced by: dedicated batch orchestration `pecos::sampling::stab(dag)` that preserves `sample_batch(N)` semantics end-to-end. Path A is rejected -- wrapping a batch primitive behind a per-shot streaming trait throws away the batch win. See `design/stab_sample_orchestration.md` for the new design. - -**Still current:** -- `DemStabSim` / `MemStabSim` pure-sim types and their crate home in `pecos-qec`. -- Noise trait hierarchy sketch (`Uniform`, `PerLocation`, `PauliLindblad`, `FromChannel`, `FromLindblad`). -- Rejection semantics for non-Clifford / adaptive circuits. - -## Goals in one paragraph (revised) - -Make the existing `pecos-qec::fault_tolerance::dem_builder` pipeline usable via two surfaces: -(1) typed pure-sim objects `DemStabSim` / `MemStabSim` (already shipped v0) for direct batch sampling and sampler introspection, -(2) a user-facing orchestration entry `pecos::sampling::stab(dag)` (proposed in `stab_sample_orchestration.md`) that does compile + batch-sample in one call. -Non-adaptive circuits only. No Stim dependency. - -## Crate layout - -Two parts: - -``` -crates/pecos-qec/src/dem_stab.rs (pure sim type; peer of fault_tolerance) -crates/pecos-engines/src/dem_stab_engine.rs (QuantumEngine impl + builder) -``` - -**Crate pivot from initial skeleton (2026-04-11).** `pecos-qec` depends on `pecos-simulators` (one-way), so a `dem_stab` module inside `pecos-simulators` would have to pull `pecos-qec` upward and create a cycle. The DemSampler / DemBuilder / DagFaultAnalyzer machinery already lives in `pecos-qec`, and DemStabSim is a thin wrapper over that machinery -- so `pecos-qec::dem_stab` is both the only legal home and the honest one. It sits as a peer of `fault_tolerance`, not inside it (it *uses* fault tolerance rather than being part of it). - -Other backends keep the `pecos-simulators` + `pecos-engines` split (`SparseStab` + `SparseStabEngine`); DemStabSim's split is `pecos-qec` + `pecos-engines` instead. Same orchestration pattern either way. - -## Public surface -- Rust - -### `pecos_simulators::dem_stab` - -```rust -pub struct DemStabSim { - dag: DagCircuit, - noise: Arc, - detectors: Vec, - observables: Vec, - - // Lazy-built, cached across shots. - sampler: OnceLock, - influence_map: OnceLock, -} - -impl DemStabSim { - pub fn builder() -> DemStabSimBuilder { DemStabSimBuilder::default() } - - /// Consume N shots. - pub fn sample_batch(&mut self, shots: usize, rng: &mut impl Rng) - -> DemStabShotBatch; - - pub fn detector_error_model(&mut self) -> &DetectorErrorModel; -} - -pub struct DemStabSimBuilder { /* private */ } - -impl DemStabSimBuilder { - pub fn circuit(mut self, dag: DagCircuit) -> Self; - pub fn tick_circuit(mut self, tc: TickCircuit) -> Self; // convenience - pub fn noise(mut self, n: N) -> Self; - pub fn detectors(mut self, d: Vec) -> Self; - pub fn observables(mut self, o: Vec) -> Self; - pub fn build(self) -> Result; -} - -pub struct DemStabShotBatch { - pub detector_flips: PackedBits2D, // shots x num_detectors - pub observable_flips: PackedBits2D, // shots x num_observables - pub measurement_record: Option, // opt-in, via MemBuilder - pub stats: SamplingStatistics, -} - -#[derive(Debug, thiserror::Error)] -pub enum DemStabError { - #[error("circuit contains classical feed-forward; use sparse_stab() for adaptive circuits")] - AdaptiveCircuit, - #[error("unsupported non-Clifford gate {0:?}; use CliffordRz or STN/MAST")] - NonClifford(GateType), - #[error(transparent)] - Builder(#[from] DemBuilderError), -} -``` - -### `DemStabNoiseModel` trait -- unified noise input - -```rust -/// Lowers to per-fault-location Pauli rates consumed by DemBuilder. -pub trait DemStabNoiseModel: Send + Sync + Debug { - fn noise_config(&self, circuit: &DagCircuit) -> NoiseConfig; -} - -// Concrete structs (same convention as DepolarizingNoise / BiasedDepolarizingNoise): -pub struct Uniform { pub p_1q: f64, pub p_2q: f64, pub p_meas: f64, pub p_prep: f64 } -pub struct PerLocation { /* HashMap */ } -pub struct PauliLindblad { pub generators: Vec<(PauliString, f64)> } // IBM-style learned -pub struct FromChannel { pub channel: ChannelMatrix } // Pauli-twirled lowering - -impl DemStabNoiseModel for Uniform { /* trivial */ } -impl DemStabNoiseModel for PerLocation { /* trivial */ } -impl DemStabNoiseModel for PauliLindblad { /* decompose generators */ } -impl DemStabNoiseModel for FromChannel { /* PTM -> Pauli rates, error on residual non-Pauli */ } -``` - -Future additions (no API impact today): `FromLindblad { op, duration }`, `FromTrajectorySamples { .. }` once item #7 (Lindblad sim) lands. - -## Engine integration -- Path A (record-and-replay) - -### `pecos_engines::dem_stab_engine` - -```rust -pub struct DemStabEngine { - n_qubits: usize, - dag: DagCircuit, - detectors: Vec, - observables: Vec, - noise: Option>, - seed: u64, - - // Built lazily on first shot_end. - sim: Option, - shot_rng: PecosRng, -} - -impl QuantumEngine for DemStabEngine { - fn process(&mut self, msg: ByteMessage) -> Result { - // 1. Decode ByteMessage into gates / measurements / shot-boundary. - // 2. If it is a gate -> push into self.dag (+ validate: no non-Clifford, no feedback). - // 3. If it is a measurement request: - // - on first call: lazy-build self.sim via DagFaultAnalyzer + DemSamplerBuilder. - // - sample one shot, return packed measurement outcomes as ByteMessage. - // - if circuit has NO measurements-used-classically, we can also defer to shot-end. - // 4. If it is a shot-reset: clear per-shot scratch (but NOT dag / sampler caches). - // (Re-entrant input = error: we only accept a single static program.) - } - fn set_seed(&mut self, seed: u64) { self.shot_rng = PecosRng::from_seed(seed); ... } - fn as_any(&self) -> &dyn Any { self } - fn as_any_mut(&mut self) -> &mut dyn Any { self } -} - -pub struct DemStabEngineBuilder { - noise: Option>, - detectors: Vec, - observables: Vec, - num_qubits: Option, -} - -impl QuantumEngineBuilder for DemStabEngineBuilder { - fn build(&mut self) -> Result, PecosError> { ... } - fn set_qubits_if_needed(&mut self, n: usize) { self.num_qubits.get_or_insert(n); } -} - -/// Free-function backend constructor, matching sparse_stab() / state_vector() convention. -#[must_use] -pub fn dem_stab() -> DemStabEngineBuilder { DemStabEngineBuilder::default() } -``` - -### Usage (Rust) - -```rust -use pecos_engines::{sim, dem_stab, ...}; - -let results = sim(program) - .quantum(dem_stab() - .detectors(detectors) - .observables(observables)) - .noise(dem_stab::Uniform { p_1q: 1e-3, p_2q: 5e-3, p_meas: 1e-3, p_prep: 1e-3 }) - .seed(42) - .run(100_000)?; -``` - -Note: the noise is set via `.noise(...)` at the `SimBuilder` level **but** DemStabSim needs it at circuit-build time, not per-gate. Solution: `DemStabEngine::build()` pulls the `NoiseModel` out of the orchestrator wiring and downcasts it to `DemStabNoiseModel` (using `as_any`). If the noise model isn't a `DemStabNoiseModel`, return `DemStabError::Builder(...)` with a clear message. Alternative: add `.dem_stab_noise(...)` on the builder to bypass the shared `.noise()` slot. Grug prefers the downcast -- keeps one noise API. - -### Python usage - -Mirror on the Python side in `pecos-rslib` / `pecos` package: - -```python -from pecos import sim -from pecos.backends import dem_stab -from pecos.noise import Uniform - -results = ( - sim(program) - .quantum(dem_stab().detectors(dets).observables(obs)) - .noise(Uniform(p_1q=1e-3, p_2q=5e-3, p_meas=1e-3, p_prep=1e-3)) - .seed(42) - .run(100_000) -) -``` - -## Rejection / validation - -DemStabEngine must reject circuits it cannot honestly handle. Two classes: - -1. **Adaptive (classical feed-forward).** If any gate's application depends on a prior measurement outcome, reject. -2. **Non-Clifford.** T / RZ / RX(theta) / etc. reject. - -Rejection happens in `process()` at ByteMessage decode time -- not at `build()` -- because the DAG is streamed in. Clear error messages that name the offending gate and point to `sparse_stab()` + `pecos-neo` or `CliffordRz` / STN as appropriate. - -## Tests (initial) - -1. **Parity test (core).** Small distance-3 repetition-code / surface-code memory experiment. Run both: - - `sim(prog).quantum(sparse_stab()).noise(DepolarizingNoise{p}).run(N)` with N = 1e5 shots. - - `sim(prog).quantum(dem_stab().detectors(...).observables(...)).noise(Uniform{...})`. - Assert detector-flip and logical-error-rate distributions match within binomial CI. Reuse `compare_dems_statistical` machinery. -2. **Rejection tests.** Assert `DemStabError::AdaptiveCircuit` on a feed-forward circuit and `NonClifford` on a T-gate circuit. -3. **DEM export parity.** Build the DEM via `DemBuilder` directly and via `DemStabSim::detector_error_model()`; assert equal via existing `compare_dems_exact`. -4. **Determinism.** Same seed, same shots -- identical results across runs. -5. **Benchmark.** `criterion` bench vs `sparse_stab` Monte Carlo for increasing N (expect crossover ~100 shots, large asymptotic speedup). - -## Out of scope for v1 - -- **Path B batch-mode fast-path** -- planned v2. Does the orchestrator surgery to let DemStabSim skip the per-shot streaming loop entirely. Grug do this *after* Path A lands so v1 doesn't drag along an orchestrator redesign. -- Non-Clifford hybrid escape (falling back to `CliffordRz` for RZ slices). Land as v2+ once basic path proven. -- GPU sampling via wgpu. Natural follow-up once CPU numbers are known. -- Lindblad-derived noise input. Blocked on trajectory sim (item #7 in literature survey). - -## v2: Path B batch-mode fast-path (sketch) - -Kept in this doc so the v1 design does not paint v2 into a corner. - -**Goal.** When `SimBuilder` is configured with a batch-capable quantum backend, bypass the per-shot classical-engine loop and feed the whole compiled program to the backend in one call. - -**Mechanism.** -- New trait in `pecos-engines`, e.g. `BatchQuantumEngine: QuantumEngine` with `run_shots(&mut self, shots: usize, rng: &mut dyn RngCore) -> ShotVec`. Default impl falls through to the current streaming loop for backends that do not implement it natively. -- `MonteCarloEngine::run(shots)` downcasts on its `QuantumEngine` trait object: if batch-capable and circuit is static (no classical feed-forward from the classical engine), call `run_shots` once; otherwise current per-shot loop. -- DemStabEngine implements `BatchQuantumEngine` natively: the internal sampler already does `sample_batch`, so `run_shots` is one call into `DemSampler::sample_batch` with a single RNG split. -- Preserves the `sim(program).quantum(dem_stab()).noise(...).run(N)` user API -- the path split is internal. - -**Design constraints v1 must preserve:** -- `DemStabEngine` already owns the built `DemSampler` across shots (Path A caches it). Path B just exposes a batch entry point alongside the streaming one. No duplication. -- DAG must be fully captured before batch execution begins -- identical to Path A's lazy-build trigger. Path A's record step is reused. -- `DemStabShotBatch` (the v1 return type of the sim) becomes the natural backing type for the batch return path. - -**What v2 does not need v1 to commit to:** -- Final form of `BatchQuantumEngine` trait (single method vs. split detect/observable/measurement). -- Whether batch fast-path is opt-in via config or auto-enabled on downcast success. - -Decide at the start of v2, with Path A's numbers as evidence. - -## Open questions - -- [ ] Should the detectors/observables live on the `DemStabEngine` builder (as drafted) or on the program IR itself (HUGR/QASM annotations)? The latter is cleaner long-term but out of scope for v1. -- [ ] `Path B` batch fast-path: useful right away (bypass classical engine) or premature? Grug lean premature -- do Path A, measure, revisit. -- [ ] How do we want to surface the DEM object for decoder hand-off? Return it from `run()` alongside shots? Provide a sidecar `.build_dem_only()` method? Likely both. -- [ ] Seeding semantics for parallel shot batches (`rayon`): per-shot seed = master_seed XOR shot_idx is deterministic and trivially parallelizable. Default to that. diff --git a/design/lindblad_magnus_algorithm.md b/design/lindblad_magnus_algorithm.md deleted file mode 100644 index 72f985aaf..000000000 --- a/design/lindblad_magnus_algorithm.md +++ /dev/null @@ -1,514 +0,0 @@ -# Algorithm Spec: Lindblad -> Pauli-Lindblad Synthesis - -Status: draft (2026-04-12) -- extracted from scout deep-read. -Pairs with: `design/lindblad_sim_skeleton.md` (uses this as the MagnusSynth kernel). - -**Primary reference.** Malekakhlagh, Seif, Puzzuoli, Govia, van den Berg, -*Efficient Lindblad synthesis for noise model construction*, npj QI 2025, -arXiv:2502.03462v1. Equation numbers below from the v1 HTML. - -**Secondary reference.** van den Berg, Minev, Kandala, Temme, -*Probabilistic error cancellation with sparse Pauli-Lindblad models*, -Nat. Phys. 2023, arXiv:2201.09866 (sparse PL generator + Pauli fidelity). - -**Source status (2026-04-12).** LaTeX tarball extracted to -`/tmp/lindblad_tex/Main.tex` (1082 lines). All closed-form $\lambda_k$ -expressions below are verbatim from the tex source; equation-label -references are authoritative. - ---- - -## 1. Inputs & outputs - -**Inputs.** -- Gate Hamiltonian $H_g \in \mathbb{C}^{d\times d}$, $d=2^n$, Hermitian, - time-(quasi-)independent in the rotating frame (paper eq. 6-8). -- Collapse operators $\{L_j\}$ with rates $\beta_j \ge 0$, or GKS matrix - $\beta_{jk}$; optional coherent shifts $\delta_j$. -- Gate duration $\tau_g$ and gate angle $\theta = \omega_g \tau_g$ - (with $\omega_g \in \{\omega_{cz}, \omega_{cx}\}$). -- Pauli basis $\mathcal{K} \subseteq \{I,X,Y,Z\}^{\otimes n}\setminus\{I^{\otimes n}\}$ - (typically weight-1 and weight-2 on device edges). -- Magnus truncation order $N \in \{1,2,3,4\}$. - -**Output.** Rate vector $\{\lambda_k\}_{k\in\mathcal{K}}$ with -$\lambda_k \ge 0$ (non-negativity only guaranteed to the truncation order; -see open questions below). - -**Assumptions.** -- Weak noise: $\beta\tau_g \ll 1$, equivalently $\beta/\omega_g \ll 1$ for - two-qubit gates. Magnus convergence radius. -- Markovianity -- time-local Lindblad master equation. -- $H_g$ time-independent in a convenient frame. Time-dependent $H_g(t)$ - requires $U_g(t) = \mathcal{T}\exp(-i\int H_g(s)\,ds)$ via piecewise - integration (not v1). - ---- - -## 2. Algorithm pseudocode - -``` -INPUT H_g, {L_j, beta_j}, tau_g, K, N -OUTPUT {lambda_k : k in K} - -// Step 1 -- interaction-frame jump operators (paper eq. 6-8) -// P_{jI}(t) = U_g(t)^dag L_j U_g(t) -// L_I(t)(rho) = -i sum_j delta_j [P_{jI}(t), rho] -// + sum_{jk} beta_{jk} ( P_{jI}(t) rho P_{kI}^dag(t) -// - 1/2 { P_{kI}^dag(t) P_{jI}(t), rho } ) -eigendecomp H_g = V D V^dag -U_g(t) = V * diag(exp(-i D t)) * V^dag // pure-phase matrix elements - // in H_g eigenbasis -PjI(t) = U_g(t)^dag * L_j * U_g(t) - -// Step 2 -- Magnus terms (paper eq. 11, 12; App. C for higher orders) -Omega_1 = integrate( L_I(t1), t1 in [0,tau_g] ) -Omega_2 = 0.5 * integrate_double( - comm( L_I(t1), L_I(t2) ), 0 <= t2 <= t1 <= tau_g ) -Omega_3 = (1/6) * integrate_triple( - comm(L_I(t1), comm(L_I(t2), L_I(t3))) - + comm(L_I(t3), comm(L_I(t2), L_I(t1))), 0 <= t3 <= t2 <= t1 <= tau_g ) -// VERIFIED prefactor is 1/12 (paper eq. TDLindPT-G4 Sol), NOT 1/24 (BCOR textbook). -Omega_4 = (1/12) * integrate_quadruple( - comm(L_I(t'), comm(L_I(t''), comm(L_I(t'''), L_I(t'''')))) - + comm(L_I(t'), comm([L_I(t''), L_I(t''')], L_I(t''''))) - + comm([[L_I(t'), L_I(t'')], L_I(t''')], L_I(t'''')) - + comm(L_I(t''), comm(L_I(t'''), comm(L_I(t''''), L_I(t')))), - 0 <= t'''' <= t''' <= t'' <= t' <= tau_g ) - -// Step 3 -- effective generator (paper eq. 9-10) -L_eff = (1/tau_g) * sum_{n=1..N} Omega_n - -// Step 4 -- Pauli twirl projection -// Twirled generator is diagonal in Pauli basis. -// Diagonal coeff: alpha_b = -(1/d) tr( P_b * L_eff(P_b) ) -// (alpha_b is a *rate* = 1/time; its integrated form is alpha_b * tau_g.) -// Rates recovered via Walsh-Hadamard on {0,1}^{2n} (2201.09866 eq. (1)): -// alpha_b = 2 sum_k lambda_k _sp // forward map -// lambda_k = -(1/4^n) sum_b (-1)^{_sp} alpha_b // for k != I -// lambda_I = 0 (by convention; not a physical rate) -// -// Derivation sketch: let W_{bk} = (-1)^{_sp}, T = sum_k lambda_k. -// Then (W lambda)_b = T - alpha_b (since _sp = (1 - W_{bk})/2). W is -// self-inverse up to a factor of 4^n, so applying W and using that -// sum_b (-1)^{_sp} vanishes for k != I gives the formula above. -// For the 1-qubit case this collapses to the direct linear solve -// lambda_X = (alpha_Y + alpha_Z - alpha_X) / 4 (etc. by symmetry). - -// Step 5 -- Dyson cross-check (paper eq. 13) -// T exp( int L_I ) = I + Omega_1 + Omega_2 + 1/2 Omega_1^2 + O(L_I^3) -// Compare Magnus-truncated channel vs Dyson-truncated channel. -``` - -**Key simplification for constant $H_g$.** Matrix elements of $P_{jI}(t)$ -in the $H_g$ eigenbasis are **pure phases $e^{i(E_a-E_b)t}$**. All Magnus -time integrals become sums of exponentials times polynomials in $t$ -- -integrate **analytically**, no numerical quadrature. This is what makes -closed-form Appendix C results possible. - -**Twirl representation.** $\mathcal{L}_{eff}$ is a $d^2\times d^2$ map -$M_d\to M_d$ in the Pauli transfer matrix (PTM) representation; the -diagonal entries are $-\alpha_b$. Off-diagonals measure residual coherence -and must be small under the weak-noise assumption -- assert -`||off-diagonal|| < tol` as a correctness check. - ---- - -## 3. Closed-form fixtures (Appendix E / `App:WhyPauliLind`) - -All expressions verbatim from `/tmp/lindblad_tex/Main.tex`. Index convention: -$P_b$ written as string label `ab` = $P_a \otimes P_b$ on (left, right) qubit; -$i\equiv I$. Rates: $\beta_{\downarrow j}$ amplitude damping on qubit $j$, -$\beta_{\phi j}$ pure dephasing on qubit $j$, for $j\in\{l, r\}$. - -### Single-qubit identity + AD + PD (exact, non-perturbative) - -Paper line 812, $\tau_g$-scale: -$$ -\lambda_x = \lambda_y = \tfrac14\beta_{\downarrow}\tau_g,\quad -\lambda_z = \tfrac12\beta_\phi\tau_g. -$$ -Not perturbative -- exact twirled result for identity. - -### Single-qubit $X_\theta$ + AD + PD (paper eqs. 869-874) - -$$ -\lambda_x = \tfrac{\theta}{4}\tfrac{\beta_\downarrow}{\omega_x}, -$$ -$$ -\lambda_y = \tfrac{2\theta+\sin 2\theta}{16}\tfrac{\beta_\downarrow}{\omega_x} - + \tfrac{2\theta-\sin 2\theta}{8}\tfrac{\beta_\phi}{\omega_x}, -$$ -$$ -\lambda_z = \tfrac{2\theta-\sin 2\theta}{16}\tfrac{\beta_\downarrow}{\omega_x} - + \tfrac{2\theta+\sin 2\theta}{8}\tfrac{\beta_\phi}{\omega_x}. -$$ - -### Two-qubit $CZ_\theta$ + AD + PD (paper eqs. 896-906) - -$\theta = \omega_{cz}\tau_g$. PD contributions separable from AD: -$$ -\lambda_{iz} = \tfrac{\theta}{2}\tfrac{\beta_{\phi r}}{\omega_{cz}},\quad -\lambda_{zi} = \tfrac{\theta}{2}\tfrac{\beta_{\phi l}}{\omega_{cz}}, -$$ -$$ -\lambda_{ix}=\lambda_{iy}=\tfrac{2\theta+\sin 2\theta}{16}\tfrac{\beta_{\downarrow r}}{\omega_{cz}},\quad -\lambda_{xi}=\lambda_{yi}=\tfrac{2\theta+\sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cz}}, -$$ -$$ -\lambda_{zx}=\lambda_{zy}=\tfrac{2\theta-\sin 2\theta}{16}\tfrac{\beta_{\downarrow r}}{\omega_{cz}},\quad -\lambda_{xz}=\lambda_{yz}=\tfrac{2\theta-\sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cz}}. -$$ -At Clifford angles $\theta = n\pi/2$ the degeneracy becomes 4-fold: -$\lambda_{ix}=\lambda_{iy}=\lambda_{zx}=\lambda_{zy}$ and -$\lambda_{xi}=\lambda_{yi}=\lambda_{xz}=\lambda_{yz}$. - -### Two-qubit $CX_\theta$ + AD + PD (paper eqs. 929-956) - -$\theta = \omega_{cx}\tau_g$. AD and PD **mix** in $\lambda_{iy}, \lambda_{iz}, -\lambda_{zy}, \lambda_{zz}$: -$$ -\lambda_{ix} = \tfrac{\theta}{4}\tfrac{\beta_{\downarrow r}}{\omega_{cx}},\quad -\lambda_{zi} = \tfrac{\theta}{2}\tfrac{\beta_{\phi l}}{\omega_{cx}}, -$$ -$$ -\lambda_{iy} = \tfrac{12\theta + 8\sin 2\theta + \sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}} - + \tfrac{4\theta - \sin 4\theta}{64}\tfrac{\beta_{\phi r}}{\omega_{cx}}, -$$ -$$ -\lambda_{iz} = \tfrac{4\theta - \sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}} - + \tfrac{12\theta + 8\sin 2\theta + \sin 4\theta}{64}\tfrac{\beta_{\phi r}}{\omega_{cx}}, -$$ -$$ -\lambda_{zy} = \tfrac{12\theta - 8\sin 2\theta + \sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}} - + \tfrac{4\theta - \sin 4\theta}{64}\tfrac{\beta_{\phi r}}{\omega_{cx}}, -$$ -$$ -\lambda_{zz} = \tfrac{4\theta - \sin 4\theta}{128}\tfrac{\beta_{\downarrow r}}{\omega_{cx}} - + \tfrac{12\theta - 8\sin 2\theta + \sin 4\theta}{64}\tfrac{\beta_{\phi r}}{\omega_{cx}}, -$$ -$$ -\lambda_{xi} = \lambda_{yi} = \tfrac{2\theta + \sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cx}},\quad -\lambda_{xx} = \lambda_{yx} = \tfrac{2\theta - \sin 2\theta}{16}\tfrac{\beta_{\downarrow l}}{\omega_{cx}}. -$$ - -**Correction from earlier scout.** Initial scout transcribed -$\lambda_{iz}=\lambda_{zz}=\frac{4\theta-\sin 4\theta}{128}\frac{\beta_{\downarrow r}}{\omega_{cx}}$ -and missed PD contributions entirely. Verbatim paper formulae above -supersede. - -### Two-qubit phase noise (subsection SubApp:2QPhNoise, lines 962-1001) - -Quadratic-in-$\delta$ dependence (coherent noise $H_\delta = (\delta/2)ZZ$). -Not transcribed here; see paper lines 962-1001 if PECOS needs coherent- -noise fixtures before v1 ships. - -### Three-qubit ZZ crosstalk (paper eqs. 1009-1011) - -**Only non-trivial case**: $CX_\theta \otimes I$ with $IZZ$ crosstalk between -target and spectator. $H_g = (\omega_{cz}/2)(IXI-ZXI)$, -$H_\delta = (\delta_{izz}/2)IZZ$. Produces weight-2 **and weight-3** PL terms: -$$ -\lambda_{iyz} = \lambda_{zyz} = \tfrac{\sin^4\theta}{16}\tfrac{\delta_{izz}^2}{\omega_{cx}^2}, -$$ -$$ -\lambda_{izz} = \tfrac{[2\theta + \sin 2\theta]^2}{64}\tfrac{\delta_{izz}^2}{\omega_{cx}^2},\quad -\lambda_{zzz} = \tfrac{[2\theta - \sin 2\theta]^2}{64}\tfrac{\delta_{izz}^2}{\omega_{cx}^2}. -$$ -**Important for PECOS:** weight-3 terms break the standard weight-2-only -sparse-PL sparsity assumption -- `PauliLindbladModel` must allow -user-specified basis $\mathcal{K}$ with weight > 2. - -### Four-qubit ZZ crosstalk (paper eqs. 1044-1062) - -Only case (iv) -- $CX_\theta \otimes X_\theta C$ with $IZZI$ crosstalk on -middle two qubits -- is non-trivial (case (iii) reduces to 3Q). Yields -weight-3 and weight-4 PL terms. - -$H_g = (\omega_{cx}/2)[(IXII-ZXII) + (IIIX-IIZX)]$, -$H_\delta = (\delta_{izzi}/2)IZZI$: -$$ -\lambda_{iyyi} = \lambda_{iyyz} = \lambda_{izzz} = \lambda_{zyyi} = \lambda_{zyyz} -= \tfrac{[4\theta - \sin 4\theta]^2}{4096}\tfrac{\delta_{izzi}^2}{\omega_{cx}^2}, -$$ -$$ -\lambda_{iyzi} = \lambda_{izyi} = \lambda_{iyzz} = \lambda_{zzyi} -= \tfrac{\sin^4\theta [3 + \cos 2\theta]^2}{256}\tfrac{\delta_{izzi}^2}{\omega_{cx}^2}, -$$ -$$ -\lambda_{iyzz} = \lambda_{zyzz} = \lambda_{zzyi} = \lambda_{zzyz} -= \tfrac{\sin^8\theta}{64}\tfrac{\delta_{izzi}^2}{\omega_{cx}^2}, -$$ -$$ -\lambda_{izzi} = \tfrac{[12\theta + 8\sin 2\theta + \sin 4\theta]^2}{4096}\tfrac{\delta_{izzi}^2}{\omega_{cx}^2}, -$$ -$$ -\lambda_{zzzz} = \tfrac{[12\theta - 8\sin 2\theta + \sin 4\theta]^2}{4096}\tfrac{\delta_{izzi}^2}{\omega_{cx}^2}. -$$ - -Note: paper appears to have duplicate labels in the first group -($\lambda_{iyyz}$ appears twice) -- possible typo; verify against any -erratum before Rust transcription. - -### Leading-order precision (paper App:LindPertPrecision) - -For $CX_{\pi/4}$ at $\beta_\downarrow/\omega_{cx} \approx 10^{-2}$: deviation -$\sim O(10^{-5})$. At $10^{-1}$: deviation $\sim O(10^{-4})$. Use as -guidance for convergence-regime defaults in `MagnusSynth`. - -**Test fixture usage.** Feed $H_{CR}$ or $H_{CZ}$ and $L\in\{\sigma^-, Z\}$ -into the algorithm; compare against closed forms to `< 1e-10`. For 3Q/4Q -crosstalk, feed $H_\delta = (\delta/2)P$ (coherent, not incoherent) and -verify quadratic scaling in $\delta$. - ---- - -## 4. Effort revision (post-latex-extract) - -**Scout initial estimate:** 200-300 formulae. **Actual (from verbatim -tex extract):** ~25-30 distinct $\lambda_k$ expressions across the -whole appendix. Most cases collapse: paper notes "the only non-trivial -case is $CX_\theta \otimes I$ with $IZZ$" etc. Much less transcription -work than scout estimated. - -Breakdown of distinct formulae: -- 1Q identity (AD+PD): 3 entries (non-perturbative). -- 1Q $X_\theta$: 3 entries with AD+PD mixing. -- 2Q $CZ_\theta$: 8 entries (mostly 2-fold/4-fold degenerate). -- 2Q $CX_\theta$: 9 entries with AD+PD mixing on 4 of them. -- 2Q phase noise: untranscribed; coherent ZZ, quadratic in $\delta$ - (lines 962-1001). -- 3Q ZZ crosstalk: 3 entries ($CX \otimes I$ only). -- 4Q ZZ crosstalk: 5 groups (many-fold degenerate) for - $CX_\theta \otimes X_\theta C$ only. - -Rust lookup form: `(gate_type, pauli_label) -> fn(theta, beta_ad_l, -beta_ad_r, beta_pd_l, beta_pd_r, omega) -> f64`. One afternoon. Test each -against a numerical Magnus order-2 integration on the same inputs. - -**Ambiguity flag.** Paper's 4Q section has an apparent label typo -(`lambda_iyyz` listed twice in one group). Manual review + possible -erratum check required. - ---- - -## 5. Sparse Pauli-Lindblad generator (arXiv:2201.09866) - -**Generator.** -$$ -\mathcal{L}(\rho) = \sum_{k\in\mathcal{K}}\lambda_k\bigl(P_k\rho P_k^\dagger - \rho\bigr), -\quad \lambda_k \ge 0. -$$ - -**Pauli fidelity (2201.09866 eq. 1, 2311.15408 eq. 1).** -$$ -f_b = \tfrac{1}{2^n}\operatorname{tr}\bigl(P_b\,\Lambda(P_b)\bigr) - = \exp\!\Bigl(-2\sum_{k\in\mathcal{K}}\lambda_k\,\langle b,k\rangle_{sp}\Bigr). -$$ - -**Symplectic inner product.** Write $P = i^{x\cdot z}X^x Z^z$, -$(x,z)\in\mathbb{F}_2^{2n}$. Then -$$ -\langle b,k\rangle_{sp} = x_b\cdot z_k + z_b\cdot x_k \pmod 2 \in \{0,1\}, -$$ -i.e. `0` if $P_b, P_k$ commute, `1` if they anticommute. Implementation: -bitwise XOR + popcount + `& 1`. `O(n/64)` per pair. - -**Forward sampling over duration $t$.** Each $k$ acts as an independent -single-Pauli channel $(1-p_k)\mathbb{1} + p_k\,P_k\cdot P_k$ with -$$ -p_k = \tfrac12\bigl(1 - e^{-2\lambda_k t}\bigr). -$$ -Per shot: for each $k$, draw Bernoulli($p_k$); if `1`, apply $P_k$. -All $|\mathcal{K}|$ draws independent, $O(|\mathcal{K}|)$ per shot. - -For PEC the signed form $\gamma_k = \text{sign}(\lambda_k)$ would be -tracked; forward QEC simulation uses $\lambda_k \ge 0$ only. - ---- - -## 6. Complexity & data structures - -- **Magnus order $N$.** Each $\Omega_n$: $n$-fold nested commutator of - $d\times d$ matrices + analytic time integral. Dominant matmul cost - $O(N\cdot d^3)$; commutator sum $O(N\cdot M^n)$ with $M$ = number of - jump operators. For $n=2$, $d=4$, $d^3=64$ -- trivial. -- **Pauli basis $\mathcal{K}$.** 1-local = $3n$; 2-local on device edges - $=9|E|$. On 100-qubit heavy-hex ($|E|\approx 140$): ~1560 terms. - $O(n^2)$ worst case. -- **Dense path memory.** State matrix $d\times d$ complex - ($16\,d^2$ bytes). PTM $d^2\times d^2$ ($16\,d^4$ bytes). For 4-qubit - ($d=16$): 0.5 MB -- fine. -- **Sparse path (> 6 qubits).** Represent $\mathcal{L}$ as a list of - `(P_j, P_k, beta_jk)` triples and form $\Omega_n$ symbolically in - Pauli basis via the Pauli-group multiplication table; never - materialize the PTM. -- **Rust types.** `faer::Mat` for small dense path ($d\le 16$). - `SparsePauliOp` (`Vec<(PauliLabel, Complex64)>`) for sparse path. - Commutators via Pauli-group table -- this is where grug gets the - 80/20 win. - ---- - -## 7. Open questions / risks - -- **Positivity of $\lambda_k$.** Magnus-truncated generator is **not - guaranteed** GKS-positive at finite order. Paper dodges via weak-noise - assumption. PECOS policy decision: clip to $\max(0, \lambda_k)$ - (lossy), warn/error on negative, or bump order (expensive). Start with - "warn + clip" and log the truncation residual. - -- **Omega_3 / Omega_4 prefactor verification.** Resolved (2026-04-12): - $\Omega_3$ has prefactor $1/6$ and $\Omega_4$ has prefactor **$1/12$** - (paper eq. TDLindPT-G4 Sol, line 688 of Main.tex), with 4 specific - nested-commutator terms explicitly listed. Note: textbook BCOR uses - $1/24$ with a different term decomposition -- the paper's form is - equivalent by commutator identities but the prefactor is $1/12$ as - written. Use paper's form verbatim. - -- **Time-dependent $H_g(t)$.** Paper assumes quasi-time-independent. - Real pulse shapes (Gaussian, DRAG) break this. Dyson path handles - numerically (time-ordered product); Magnus path needs piecewise - integration. Out of scope v1. - -- **Catastrophic cancellation near $\theta=0$.** Formulae like - $(2\theta-\sin 2\theta)/16$ lose precision at small $\theta$ - ($\approx \theta^3/6$). Rust impl **must** use a Taylor branch for - $|\theta|<\epsilon$. Standard `sinmx` trick; test with - $\theta=10^{-10}$. - -- **PTM off-diagonal residuals.** Weak-noise -> near-diagonal in Pauli - basis. Assert `||off-diagonal|| < tol`; do not silently discard. - -- **Pauli basis $\mathcal{K}$ completeness.** If physical noise generates - a $\lambda_k$ outside $\mathcal{K}$ (e.g. amplified weight-3 ZZ), it is - silently dropped on projection. Log the norm of the projected-away part; - error if above a user-settable threshold. - ---- - -## 8. Implementation phases - -**Phase 1 -- numerical (gold standard).** -Eigendecompose $H_g$, integrate $\Omega_1$ and $\Omega_2$ analytically in -the eigenbasis, assemble $\mathcal{L}_{eff}$ as a PTM, diagonal-read the -$\alpha_b$, Walsh-Hadamard to $\lambda_k$. Test against Table 1 (CX, -amplitude damping, right qubit only). This is the order-2 MagnusSynth -default. - -**Phase 2 -- sparse Pauli-Lindblad sampler + DemStabSim glue.** -Implement `PauliLindbladModel::sample(t)` via independent Bernoullis -(Section 5). Implement `DemStabNoiseModel` for `PauliLindbladModel` -(skeleton Section "Glue into DemStabSim"). Rep-code memory experiment -parity test. - -### Shipped work (2026-04-13) - -Implemented in `exp/pecos-lindblad/` Phases 1-5: - -| # | Scope | Phase | -|---|---|---| -| 1 | 1Q identity (exact) | [shipped] | -| 2 | 1Q X_theta (leading-order) | [shipped] | -| 3 | 2Q CZ_theta + n-qubit Walsh-Hadamard | [shipped] | -| 4 | 2Q CX_theta + block-diagonal exp | [shipped] | -| 5 | PL summary helpers + DemStabSim scalar-collapse scaffold | [shipped] | - -28 tests verify all four paper closed-form fixtures (1Q ident, X_theta, -CZ_theta, CX_theta) to tol 1e-8 (1e-12 for the exact identity result). - -### Order-1 scope limit - -The `synthesize_numerical` entry point implements **Omega_1 only**. This is -correct and tight for incoherent noise (amplitude damping, pure -dephasing) because the rates enter linearly in `beta`. Coherent noise -cases (2Q phase noise, 3Q ZZ crosstalk, 4Q ZZ crosstalk) have rates -**quadratic in delta** and require Omega_2 + Pauli-twirl: - -- For purely coherent `L(rho) = -i[H_delta, rho]`: - `Tr(P_b * L(P_b))/d = 0` (first-order diagonal element vanishes by - cyclicity of trace for Hermitian H_delta). -- Thus the Omega_1-diagonal shortcut gives `alpha_b = 0`, and the - extracted `lambda_k = 0`, which is wrong. -- The correct second-order result comes from twirling the full channel - `exp(Omega_1 + Omega_2 + ...)`, where quadratic cross-terms in the - expansion produce non-vanishing Pauli-diagonal contributions. - -### Non-Markovian (TCL) support (2026-04-14) - -Time-convolutionless (time-local) master equations are supported via -`TimeDepLindbladian` + `synthesize_superop_time_dep`. The form - -```text -drho/dt = -i [H_delta(t), rho] + sum_j gamma_j(t) * D[c_j] rho -``` - -with arbitrary time-dependence in `gamma_j(t)` and `H_delta(t)` is handled -by per-slice superoperator evaluation. Covers 1/f dephasing (verified -against analytic integrated-rate formula `gamma_0 * tau_g * ln(3)/4`), -Gaussian coherence decay, coloured coherent noise, and pulse-dependent -dephasing. - -**Genuinely structural limit**: time-nonlocal master equations of -Nakajima-Zwanzig form - -```text -drho/dt = int_0^t K(t-s) rho(s) ds -``` - -require convolution over the history of `rho` and are out of scope. These -describe strongly-coupled reservoirs with long memory times; TCL -approximation (which we support) captures the vast majority of -near-Markovian deviations seen in superconducting / trapped-ion / -neutral-atom qubits. - -### Open for future phases - -- Phase 6: coherent-noise path. Either (a) implement Omega_2 + twirl, or - (b) add general `d x d` Hermitian matrix exponentiation and compute the - exact channel `U_err rho U_err^dag`. Target: 3Q IZZ crosstalk - (paper eqs. 1009-1011, weight-3 rates). -- Phase 7: proper `pecos-qec::NoiseConfig` generalization and - per-gate-type Pauli-Lindblad input to `DemStabSim` (see - `design/lindblad_sim_skeleton.md` "Glue into DemStabSim" section). -- Phase 8: 4-qubit ZZ crosstalk with weight-4 rates (paper eqs. - 1044-1062). Blocked on Phase 6. - -**Phase 3 -- closed-form Appendix C lookup.** -Transcribe Tables 1-2 into a Rust `const` table keyed by -`(GateType, PauliLabel)`. Property-test each entry against Phase 1 -numerical path. Add Taylor branches for small $\theta$. - -**Phase 4 -- higher-order Magnus.** -Implement $\Omega_3, \Omega_4$ with Blanes-Casas-Oteo-Ros; verify against -Phase 3 + Phase 1 random Lindbladians. Out-of-regime detection. - -**Phase 5 -- Appendix D multi-qubit ZZ crosstalk.** -Re-scrape paper for D.7/D.8 formulae. Transcribe. Property-test. 200-300 -entries. - -Phases 1-2 are the MVP that unblocks DemStabSim-with-Lindblad-noise. -Phases 3-5 are refinements. - ---- - -## 9. References - -Paper: -- arXiv:2502.03462 -- Malekakhlagh et al., *Efficient Lindblad synthesis* -- arXiv:2201.09866 -- van den Berg et al., *Sparse Pauli-Lindblad PEC* -- arXiv:2311.15408 -- Chen et al., *Learning sparse PL* - -Cross-check: -- arXiv:2407.03576 -- 4th-order commutator-free Magnus in Liouville space -- Blanes, Casas, Oteo, Ros, *The Magnus expansion and some of its - applications* (Phys. Rep. 2009) -- textbook for $\Omega_n$ formulae - -Next scout TODO: -- 2Q phase noise (paper subsection SubApp:2QPhNoise, lines 962-1001): - coherent-noise test fixtures. Low priority; only needed if coherent - $ZZ$ test path is in v1. -- Verify paper's apparent 4Q label typo ($\lambda_{iyyz}$ listed twice). - -Source checked out at `/tmp/lindblad_tex/Main.tex` (ephemeral). For a -permanent copy, pull from `arxiv.org/e-print/2502.03462`. diff --git a/design/lindblad_sim_skeleton.md b/design/lindblad_sim_skeleton.md deleted file mode 100644 index ada291973..000000000 --- a/design/lindblad_sim_skeleton.md +++ /dev/null @@ -1,420 +0,0 @@ -# Lindblad / Trajectory Simulator -- Module Skeleton - -Status: draft (2026-04-12) -Target crate: new `pecos-lindblad` (or module inside `pecos-neo`; decision below) -Pairs with: `design/qec_sim_literature.md` (#7), `design/lindblad_magnus_algorithm.md` (math spec + closed forms), `design/dem_stab_sim_skeleton.md`, `design/stab_sample_orchestration.md` - -## Goals in one paragraph - -Add a continuous-time open-system simulator to PECOS that bridges device physics -to the existing DEM / stabilizer pipeline via a **gate + duration -> effective -Pauli-Lindblad rates** lowering (arXiv:2502.03462). Offer two surfaces: -(a) `Gate -> Magnus-on-superoperator -> PauliLindbladModel -> DemStabSim` -for fast Pauli-twirled noise used in QEC threshold sweeps, and -(b) a direct `LindbladTrajectorySim` (MCWF / quantum jumps) for small circuits -(<= 10 qubits) to validate the twirl and to expose coherent / non-Pauli effects -that a twirled DEM misses (arXiv:2402.16727, 2510.23797). -Keep scope minimal: adaptive Dormand-Prince solver, dense `faer::Mat`, rayon -fan-out on trajectories. No MPS, no Krylov, no GPU on v1. - -## Why now (one-liner per literature scout) - -Nobody in the mature Python/Julia stack (QuTiP, Dynamiqs, QuantumToolbox.jl) -exposes the `Lindbladian + gate_duration -> PauliLindbladModel` API. This is -the wedge. Everything else is the 80/20 ODE plumbing. - -## Two-path architecture - -``` - +----------------------+ -Gate { H_ideal, H_err, c_ops, duration } | PauliLindbladModel | - | | { supports, rates }| - | Magnus / Dyson on superoperator +----------+-----------+ - | (arXiv:2502.03462) | - v | feeds -(a) Pauli-twirled -> PauliLindbladModel -------------------> DemStabSim - (fast, threshold sweeps) - -Gate { ... } + initial |psi> - | - | MCWF / quantum jumps (Daley 2014) - | dense n x n, adaptive RK (Dormand-Prince) - v -(b) LindbladTrajectorySim ------> syndrome samples -> learned DEM - (captures coherent - hyperedges twirl misses) -``` - -Both paths share `Gate`, `Lindbladian`, and `PauliBasis` primitives. Path (a) -is the MVP and the integration with `DemStabSim`. Path (b) is the reference -validator -- small but honest. - -## Crate placement (decision) - -**Proposal: new crate `crates/pecos-lindblad`** peer of `pecos-neo`, not inside -it. Reasons: - -1. `pecos-neo`'s `NoiseChannel` trait is sample-only (`NoiseResponse` is - a Pauli-injection enum). Lindblad synthesis lowers *to* rates; trajectory - sim lowers *to* a stream of pure-state wavefunctions. Neither fits the - current trait without widening it. Keep trait lean; add a sibling crate - that *feeds* it. -2. Lindblad sim pulls in `faer` + `ode_solvers` (or `diffsol`). `pecos-neo` - today only has `rand`, `rayon`, `smallvec`. Don't fatten the base crate. -3. Clean cut: `pecos-lindblad` produces `PauliLindbladModel` and - `TrajectoryShot`; `pecos-neo` and `pecos-qec::dem_stab` consume them. - -Alternative considered: put behind a feature flag inside `pecos-neo`. -Rejected -- feature flags on numerics crates become build-matrix purgatory. - -## Crate layout - -``` -crates/pecos-lindblad/ - Cargo.toml # faer, ode_solvers (or diffsol), rand, rayon, thiserror - src/ - lib.rs - basis.rs # PauliBasis, PauliString, SparsePauliOp - lindbladian.rs # Lindbladian { H: Matrix, c_ops: Vec } - gate.rs # Gate { ideal: UnitaryRep, H_drive(t), c_ops, duration } - magnus.rs # Magnus/Dyson on superoperator -> effective generator - pauli_twirl.rs # Liouvillian -> diagonal in Pauli basis -> rates - trajectory.rs # MCWF / quantum jumps unraveling (Path b) - solver.rs # thin Dormand-Prince wrapper over faer state - api.rs # public builders: MagnusSynth, TrajectorySim - tests/ - parity_small.rs # symbolic case from arXiv:2502.03462 Appendix C - trajectory_vs_me.rs # mcwf(N) -> rho_avg vs mesolve, within statistical CI - pauli_twirl_roundtrip.rs -``` - -Integration-side additions (kept in owning crates): - -``` -crates/pecos-qec/src/dem_stab.rs - + DemStabNoiseModel impl for pecos_lindblad::PauliLindbladModel -crates/pecos-neo/src/noise/lindblad_derived.rs - + Cached LindbladChannel(table: HashMap<(GateId, OrderedFloat), PauliChannel>) -``` - -## Public surface -- Rust - -### Core types - -```rust -/// Sparse Pauli-basis decomposition (arXiv:2201.09866 generator form). -pub struct PauliLindbladModel { - pub supports: Vec, - pub rates: Vec, // lambda_k >= 0 -} - -impl PauliLindbladModel { - /// p_flip for Pauli k over duration t: (1 - exp(-2 lambda_k t)) / 2. - pub fn flip_probs(&self, t: f64) -> Vec; - - /// Sample one realization over duration t. - pub fn sample(&self, t: f64, rng: &mut impl Rng) -> SparsePauliOp; -} - -/// Time-independent collapse-operator Lindbladian. -/// Time-dependent H is handled on `Gate` via H_drive(t) closure. -pub struct Lindbladian { - pub hamiltonian: FaerMat, // n x n - pub collapse_ops: Vec<(FaerMat, f64)>, // (c_k, gamma_k) -} - -pub struct Gate { - pub label: &'static str, - pub ideal: UnitaryRep, // for sanity-check / inverse - pub drive_hamiltonian: Option FaerMat + Send + Sync>>, - pub static_lindbladian: Lindbladian, // H_err + c_ops during the gate - pub duration: f64, -} -``` - -### Path (a): Magnus synthesis - -```rust -pub struct MagnusSynth { - order: u8, // 1, 2, 3, 4 (paper goes to 4) - twirl: bool, // default true for PauliLindbladModel output - basis: PauliBasis, // sparse by default, up to weight-2 -} - -impl MagnusSynth { - pub fn synthesize(&self, gate: &Gate) -> Result; - - /// Untwirled variant: full Liouville generator (useful for (b) validation). - pub fn synthesize_generator(&self, gate: &Gate) - -> Result, SynthError>; -} - -/// Grug-fallback: numerical integration of the Liouvillian directly, no Magnus. -/// Use as gold standard; slow but unambiguous. -pub fn synthesize_numerical(gate: &Gate, rtol: f64, atol: f64) - -> Result, SynthError>; -``` - -### Path (b): trajectory simulator - -```rust -pub struct TrajectorySim { - initial_state: StateVec, - gate_sequence: Vec, - num_trajectories: usize, - seed: u64, -} - -impl TrajectorySim { - pub fn builder() -> TrajectorySimBuilder { ... } - - pub fn run(&self) -> TrajectoryBatch; // rayon fan-out -} - -pub struct TrajectoryBatch { - pub final_states: Vec, // one per trajectory - pub jump_records: Vec>, // when / which c_op fired - pub measurement_outcomes: Option, -} -``` - -### Glue into DemStabSim - -**Current state (2026-04-13).** `pecos-qec::dem_stab::DemStabSim::builder() -.noise(...)` only accepts `NoiseConfig { p1, p2, p_meas, p_init }` -- -four scalar uniform-depolarizing probabilities. `PauliLindbladModel`'s -per-Pauli per-gate rates do not fit this shape without loss. - -**Scaffold integration shipped** in -`exp/pecos-lindblad/tests/dem_stab_integration.rs`: collapse the PL model -to `p1 = pl_1q.total_rate()` and `p2 = pl_cx.total_rate()` and feed those -scalars to `NoiseConfig::new(p1, p2, 0.0, 0.0)`. End-to-end flow works, -but the collapse loses per-Pauli structure -- order of magnitude right, -per-Pauli wrong (treats AD+PD as symmetric X/Y/Z). - -**Proper integration requires changes in `pecos-qec`** (out of scope for -`pecos-lindblad`): - -```rust -// Future API, once NoiseConfig is generalized: -impl DemStabNoiseModel for pecos_lindblad::PauliLindbladModel { ... } - -let pl_noise = synthesize_numerical(&gate_cx, DEFAULT_N_STEPS); -let sim = DemStabSim::builder() - .circuit(dag) - .noise(pl_noise) // directly consumed, no scalar collapse - .detectors(...) - .observables(...) - .build()?; -``` - -Required changes on `pecos-qec` side: -1. `NoiseSpec` trait or enum generalizing `NoiseConfig`. At minimum two - variants: `Uniform { p1, p2, p_meas, p_init }` (current) and - `PerGatePauliLindblad { per_gate_type: HashMap }`. -2. `DemSamplerBuilder::with_noise_spec(...)` replacing scalar `.with_noise(...)`. -3. Mechanism builder: instead of splitting `p1` into `X/Y/Z` with weight - `1/3` each, read per-Pauli rates from the `PauliLindbladModel` for - that gate type. - -Land this as a separate PR against `crates/pecos-qec/`; `pecos-lindblad` -stays as the pure-math supplier. - -### Glue into pecos-neo (non-DEM stabilizer Monte Carlo) - -For researchers who want realistic noise on a `sparse_stab()` run without the -DEM detour: cache the Magnus output per gate and expose it as a -`NoiseChannel` that injects Pauli samples. - -```rust -// in pecos-neo::noise::lindblad_derived -pub struct LindbladChannel { - // (GateId, duration_ns) -> precomputed PauliLindbladModel - table: HashMap<(GateId, OrderedFloat), PauliLindbladModel>, -} - -impl NoiseChannel for LindbladChannel { - fn apply(&self, event: &NoiseEvent, ctx: &mut NoiseContext, rng: &mut PecosRng) - -> NoiseResponse { - // look up (gate_id, duration) in table; sample Pauli; InjectGates - } -} -``` - -**Pre-req path (audit 2026-04-12, revised).** No first-class duration field -exists on `GateCommand` / `NoiseEvent::AfterGate`. Instead of a schema change, -use the existing `TickCircuit` / `DagCircuit` `Attribute` metadata dictionary -(`crates/pecos-quantum/src/tick_circuit.rs:1147`): standardize on the key -`"gate_duration"` = `Attribute::Float(nanoseconds)`. The `pecos-neo` circuit -converter reads this key at translation time into `GateCommand`, and -`LindbladChannel` queries it via `ctx` at apply time. Zero breaking changes -to core circuit types. The schema-extension option (adding -`duration: Option` to `NoiseEvent::AfterGate`) is reserved for a -later PR if the metadata convention proves insufficient -- grug do not prepay -that complexity. - -## Noise-model input hierarchy - -| Input shape | Path to DEM | Who produces it | -|---|---|---| -| Ideal + per-qubit T1/T2 + gate duration | Magnus (1st order enough) | user spec | -| + coherent over-rotation / miscalibration | Magnus (2nd-4th order) | user spec or fit | -| + 2Q ZZ crosstalk | Magnus (closed-form from 2502.03462 Appendix D) | user spec | -| Learned sparse PL from device (PEC) | direct -- already PauliLindbladModel | cycle-benchmarking fit (future `pecos-char` crate?) | -| General CPTP / Choi channel | Pauli-twirl -> rates | `synthesize_numerical` then twirl | - -## Solver choice - -Default: **adaptive Dormand-Prince 5(4)** via `ode_solvers` (nalgebra-native, -simple) or `diffsol` (more features, BDF for stiff). Tolerances `rtol=1e-6`, -`atol=1e-9`. Pack `Complex64` as interleaved `[re, im, re, im, ...]` -`Vec` for solver input (both crates are real-only). - -Magnus integrand evaluation: closed-form first order, trapezoidal second-order -nested, adaptive Gauss-Kronrod for third/fourth order (or punt to -`synthesize_numerical` for order > 2). Grug vote: ship order-2 as default; add -higher orders only when a test case demands. - -## State representation - -Keep density matrix as `faer::Mat` of size `n x n` (QuTiP's -`matrix_form` trick). Apply `-i[H, rho] + sum_k (c_k rho c_k^dag - -(1/2){c_k^dag c_k, rho})` directly. Avoid materializing the `n^2 x n^2` -superoperator except for Pauli-transfer-matrix extraction. Crossover to -vectorized superop at `n <= 4 qubits` via a cfg-gated fast path; do not -implement v1. - -Pauli basis representation: `PauliString` = pair of `BitVec` (x-part, z-part) -plus sign/phase. Sparse storage `Vec<(PauliString, f64)>` for -`PauliLindbladModel`. Up to weight-2 by default; weight-3+ opt-in. - -## Trajectory parallelization - -- `rayon::par_iter` over `0..num_trajectories`. -- Each trajectory gets its own `rand_chacha::ChaCha12Rng` seeded from - `master_seed.wrapping_add(trajectory_idx as u64)`. Deterministic under - parallel execution. -- No GPU on v1. (Dynamiqs-style `vmap+jit` is the future win but requires - wgpu/CUDA ODE integrator -- defer until CPU numbers demand.) - -## Tests (initial) - -1. **Magnus parity vs paper.** Reproduce the amplitude-damping-under-identity - and the cross-resonance CX symbolic rates from arXiv:2502.03462 Appendix C - within `< 1e-10`. Freeze numerical values as test fixtures. -2. **Magnus vs numerical.** For random Lindbladians with `beta/omega_g < 0.1`, - compare `MagnusSynth::order(4)` against `synthesize_numerical` -- should - match within `< 1e-6`. -3. **Magnus out-of-regime detection.** At `beta/omega_g = 1.0`, Magnus order-2 - vs order-4 should diverge; `SynthError::OutOfConvergenceRegime` must fire. -4. **Trajectory vs master equation.** For 1-qubit T1 decay, 10k trajectories - averaged should match `mesolve` output within binomial CI. -5. **Pauli twirl round-trip.** `Liouvillian -> twirl -> Pauli rates -> sample - -> average` must match the diagonal of the twirled generator. -6. **End-to-end DemStabSim glue.** Small rep-code memory experiment: feed - `MagnusSynth` output to `DemStabSim`, compare logical error rate against - the trajectory path (path b) on the same circuit. -7. **Integration regression.** Once the `"gate_duration"` metadata convention - lands in `pecos-neo`'s circuit converter, add a parity test with - `LindbladChannel` vs `DemStabSim + PauliLindbladModel` on the same - circuit annotated with per-gate durations. - -## Rejection / validation - -- Non-Hermitian `H_drive`: reject at `Gate` construction. -- Non-CP `c_ops` (gamma_k < 0): reject. Pseudo-Lindblad (arXiv:2306.14876) - opt-in only. -- Magnus convergence check: estimate `||beta|| * duration` vs `||H_ideal||`; - emit warning if > 0.3, error if > 1.0 (tunable). -- Time-ordered integrals of `H_drive(t)`: require user-supplied `Fn(f64)` - plus optional `sample_points` hint; otherwise adaptive. - -## Out of scope for v1 - -- **GPU solver path.** Natural follow-up once CPU numbers are known. -- **MPS / tensor-network Lindblad.** Too far from the wedge. -- **Non-Markovian (Redfield, HEOM) solvers.** Separate design. -- **Stochastic master equation (SME) / diffusive unravelings.** Separate design. -- **Krylov / expm-based propagators.** Default is adaptive RK; add later if - stiffness demands. -- **Magnus as time-stepping integrator.** Different use (arXiv:2407.03576); - here Magnus is for effective-generator synthesis only. -- **Leakage-aware Lindblad.** Needs 3-level model; design separately - (see scout open question on leakage). - -## Open questions - -- [ ] Crate name: `pecos-lindblad` vs `pecos-open-system` vs fold into - `pecos-neo`. Grug prefers `pecos-lindblad` -- says what it is. -- [ ] Magnus order default: 2 (cheap, closed-form) or 4 (paper's highest). - Probably 2; 4 as opt-in for research. -- [ ] Should `PauliLindbladModel` live in `pecos-lindblad` or promoted to - `pecos-qec` so `DemStabSim` can consume it without a dependency flip? - Lean `pecos-qec` -- it's a noise format, not Lindblad-specific. -- [ ] Symbolic vs numerical Appendix-D (ZZ crosstalk) formulae: - can we parse paper's LaTeX / Mathematica output, or transcribe? Manual - transcription of 3-4 closed forms is honest work; skip symbolic - pipelines. -- [x] Gate-duration data path (**audit 2026-04-12**): no first-class field - on `GateCommand`, `TickCircuit`, `DagCircuit`, or `NoiseEvent::AfterGate`. - Only `GateCommand::idle(qubit, duration)` (stashed in `angles`, see - `exp/pecos-neo/src/command.rs:296`) and `NoiseEvent::IdleTime { duration }` - (`exp/pecos-neo/src/noise.rs:203-206`) carry duration today. **Decision:** - use `TickCircuit` / `DagCircuit` `Attribute` metadata dictionary - (`crates/pecos-quantum/src/tick_circuit.rs:1147`) with standardized key - `"gate_duration"` = `Attribute::Float(ns)`. Lower-risk than a schema - change; zero breaking changes to core circuit types. The - `pecos-neo/src/circuit.rs` converter reads this key when translating - to `GateCommand`; `LindbladChannel` queries it at lookup time. Promote - to a first-class field on `NoiseEvent::AfterGate` only if the metadata - convention proves itself insufficient in practice. -- [ ] Seeding semantics for `MagnusSynth` (deterministic, no RNG needed) vs - `TrajectorySim` (per-trajectory seed). Document clearly. - -## Build order - -1. **`pecos-lindblad` crate scaffold** + `PauliBasis` + `Lindbladian` + - `Gate` types. Tests: round-trip Pauli ops, Lindbladian constructor sanity. -2. **`synthesize_numerical`** (gold-standard, slow). One integrator, one pass. - Tests: trajectory-vs-mesolve (test #4) uses this. -3. **`MagnusSynth::order(1)` + `order(2)`** with twirl. Tests: parity vs - `synthesize_numerical` + paper fixtures (tests #1, #2, #5). -4. **Glue into `DemStabSim`** -- implement `DemStabNoiseModel` for - `PauliLindbladModel`. Tests: #6. -5. **`TrajectorySim`** (Path b) -- MCWF, rayon fan-out. Tests: #4 properly, - small rep-code validation run. -6. **`"gate_duration"` metadata convention + `LindbladChannel`** in - `pecos-neo` (converter reads `TickCircuit` attribute; channel looks up - cached Pauli rates). Tests: #7. -7. **Higher-order Magnus (3, 4)** + convergence detection. Tests: #3. - -Stop after step 4 if that's all that's needed for the next research run. -Steps 5-7 unlock honest coherent-error studies but are not on the critical -path for Pauli-noise threshold sweeps. - -## References - -Must-read: -- arXiv:2502.03462 -- Magnus/Dyson Lindblad synthesis (**the algorithm**) -- arXiv:2201.09866 -- sparse Pauli-Lindblad generator form -- arXiv:2311.15408 -- learning sparse PL models -- arXiv:2402.16727 -- when Pauli approximation underestimates QEC failure -- arXiv:2510.23797 -- coherent-error hyperedges missing from twirled DEMs -- arXiv:2407.03576 -- 4th-order commutator-free Magnus (gold-standard cross-check) -- Daley 2014 (Adv. Phys.) -- MCWF review - -Should-read: -- arXiv:2406.08981 -- Bayesian CPTP learning from syndromes -- arXiv:2512.10814 -- decoder-free DEM estimation on Willow -- arXiv:2504.21440 -- QuantumToolbox.jl architecture - -Nice-to-have: -- arXiv:2306.14876 -- pseudo-Lindblad trajectories for non-GKSL -- arXiv:2405.12925 -- Magnus superconvergence (Hamiltonian sim) -- arXiv:2107.10054 -- periodic-Lindblad high-frequency expansion - -Rust crates evaluated: -- `diffsol` (stiff + non-stiff, dense+sparse, nalgebra/faer) -- `ode_solvers` (simpler, nalgebra-native) -- `faer` (fast dense linalg) -- `rand_chacha` (per-trajectory seeding) diff --git a/design/qec_sim_literature.md b/design/qec_sim_literature.md deleted file mode 100644 index 7180a6841..000000000 --- a/design/qec_sim_literature.md +++ /dev/null @@ -1,484 +0,0 @@ -# QEC Simulator Literature Survey: Candidate Gaps in PECOS - -Status: draft / scaffold -Scope: quantum **simulators** (not decoders) useful for QEC research that PECOS does not currently implement or is not actively working on. - -## Current PECOS simulator coverage (for reference) - -| Family | PECOS impl | -|---|---| -| Stabilizer tableau (sparse/dense) | `SparseStab`, `DenseStab`, `GpuStab` (wgpu), `CuStabilizer`, `pecos-cppsparsestab` | -| State vector | `StateVec` (SoA/AoS), `CuStateVec`, Qulacs, QuEST | -| Density matrix | `DensityMatrix`, `CuDensityMat`, QuestDensityMatrix | -| Clifford + T / CH-form | `CliffordRz` | -| Stabilizer + tensor network / magic states | `STN` (stabilizer tableau + MPS), `MAST` (magic-state injection + deferred ancilla projection, Clifford disentangling) -- active on branch/worktree `study/tensor-network-clifford-rz` | -| Tensor network | `CuTensorNet` | -| Pauli propagation | `PauliProp` | -| Graph state | `GraphStateSim` | -| ZX calculus | `pecos-zx` (exp) | -| Composable noise | `pecos-neo` (exp) | -| **Detector Error Model (Stim-compat)** | `pecos-qec::fault_tolerance::dem_builder` -- `DemBuilder` + `DemSamplerBuilder` (SoA batch sampler) | -| **Stabilizer-rank / sum-over-Cliffords** | `CliffordRz` via CH-form sum decomposition (Bravyi 1808.00128) | - -## Out-of-scope (already covered or actively developed) - -Do **not** propose these as gaps: - -- **Stim-style DEM generation and sampling** -- `pecos-qec::fault_tolerance::dem_builder` (`DemBuilder`, `DemSamplerBuilder`). -- **Stabilizer-rank / sum-over-Cliffords simulation** -- `CliffordRz` (CH-form, Bravyi 1808.00128). -- **Stabilizer + tensor-network hybrids / magic-state injection via MPS** -- `STN` and `MAST` on branch/worktree `study/tensor-network-clifford-rz`. -- **Composable gate-level noise channels** -- `pecos-neo` (depolarizing, measurement, idle, crosstalk, leakage, custom). - -Sections below that originally proposed any of these have been revised to focus on *refinements* or *wrapper backends* rather than net-new simulators. - -## Candidate gap families - -Each entry below is a simulation family that appears **not covered** by the above. TODOs mark items still to validate. - ---- - -### 1. (REVISED) Alternatives to PECOS's existing DEM sampler - -**Correction.** PECOS **already has** a Stim-compatible DEM generator and fast batch sampler at `crates/pecos-qec/src/fault_tolerance/dem_builder/`: `DemBuilder` (per-qubit fault model, 15 Pauli combos for 2Q gates, Stim-format output, hyperedge decomposition for MWPM) and `DemSamplerBuilder` (SoA / CSR / bit-packed u64 / rayon batch sampling). - -**So the real question is:** what *simulator backends* could feed or complement the existing DemSampler? - -The DemSampler today operates on a `DagFaultInfluenceMap` produced by circuit-level *fault propagation analysis* (not a full quantum sim). That is deliberate and fast, but it assumes Pauli/depolarizing-tractable noise. Gaps worth a literature hunt: - -- **Stim as a cross-validation backend.** Wrap `stim.Circuit -> DEM` via PyO3/FFI so PECOS circuits can be round-tripped through Stim and diffed against PECOS's own DEM. Test harness already exists (`test_dem_sampler_vs_stim.py`). Worth formalizing as a first-class optional backend. -- **Coherent / non-Pauli noise -> effective DEM.** For circuits with rotations, coherent over-rotations, leakage, crosstalk, the Pauli-twirled DEM loses information. Candidates to compute an *approximate* DEM from a richer sim: - - Lindblad / trajectory sim (see #7 below) -> tomographic per-location Pauli channel -> feed into DemBuilder. - - Pauli-Lindblad learned models (see #9) -> sparse correlated error mechanisms as DEM hyperedges. - - Matchgate / FLO (see #2) where tractable, for exact coherent error rates on small gadgets. -- **Non-Clifford logical gadgets.** For T / magic-state circuits, the influence-map pipeline must handle non-Pauli effects. `CliffordRz` (CH-form sum) is a candidate backend for an "exact small-DEM" oracle used to validate approximations. - -**Seminal / anchor refs.** -- C. Gidney, *Stim: a fast stabilizer circuit simulator*, Quantum 5, 497 (2021). arXiv:2103.02202 -- Stim's DEM spec + Sinter sampling harness (docs). - -**Action items.** -- [ ] Survey how Stim, qec_lib, and qsim's circuit-level noise adapters handle non-Pauli noise lowering. -- [ ] Decide whether PECOS's DemBuilder gains a `from_channel(qubit_op, ...)` entry point that accepts PTM / Choi / Lindblad and lowers to Pauli rates. -- [ ] Evaluate PyO3 `stim` bridge as an optional cross-check backend. - ---- - -### 2. Matchgate / Free-fermion / Fermionic-linear-optics (FLO) simulators - -**What it is.** Efficient classical simulation of matchgate circuits (nearest-neighbor 2-qubit gates satisfying matchgate identities) via covariance-matrix evolution. Equivalent to non-interacting fermion dynamics. - -**Why QEC needs it.** Majorana / fermionic codes, certain LDPC constructions built from free-fermion layers, boundary-matching benchmarks, noise models where errors are Gaussian-fermionic. Also useful as a sanity-check oracle for small non-Clifford circuits that happen to be matchgate-reducible. - -**PECOS status.** Not present. - -**Seminal refs.** -- Valiant, *Quantum circuits that can be simulated classically in polynomial time*, SIAM J. Comput. 31 (2002). -- Knill, *Fermionic Linear Optics and Matchgates* (2001), arXiv:quant-ph/0108033. -- Terhal, DiVincenzo (2002), arXiv:quant-ph/0108010. -- Jozsa, Miyake, *Matchgates and classical simulation of quantum circuits*, Proc. R. Soc. A 464 (2008). - -**Existing OSS.** -- `Flo-simulator` (GitHub academic repo) -- matchgate + non-Gaussian gate simulator (Cudby-Strelchuk 2024, arXiv:2307.12702 / Quantum 2024). -- OpenFermion-FQE (fermionic quantum emulator; second-quantized, not matchgate-specialized but adjacent). -- No widely-used production library -- niche for PECOS. - -**Newer ref worth tracking.** -- Cudby, Strelchuk, *Improved simulation of quantum circuits dominated by free fermionic operations*, Quantum 8 (2024), DOI 10.22331/q-2024-12-04-1549. - ---- - -### 3. Decision-diagram simulators (QMDD / DDSIM) - -**What it is.** Represent state/operator as a reduced decision diagram (QMDD, TDD, LIMDD). Exponential compression on structured circuits, exact non-Clifford. - -**Why QEC needs it.** Exact verification of small logical gadgets (magic-state distillation circuits, small code blocks), cross-checking approximate sims, equivalence checking of compiled vs logical circuits. - -**PECOS status.** Not present. - -**Seminal refs.** -- Miller, Thornton, *QMDD: A Decision Diagram Structure for Reversible and Quantum Circuits* (2006). -- Zulehner, Wille, *Advanced Simulation of Quantum Computations*, IEEE TCAD (2019). -- Vinkhuijzen et al., *LIMDD: A Decision Diagram for Simulation of Quantum Computing Including Stabilizer States*, Quantum 7 (2023). - -**Existing OSS.** -- MQT DDSIM (Munich Quantum Toolkit) -- C++20/Python, actively maintained: https://github.com/munich-quantum-toolkit/ddsim -- LIMDD branch of DDSIM: https://github.com/munich-quantum-toolkit/ddsim/tree/limdd -- first LIMDD implementation, compactly represents stabilizer states *and* DD-friendly non-stabilizer states. -- Q-Sylvan (parallel DD package for quantum, Springer 2025). - -**Newer ref worth tracking.** -- Vinkhuijzen et al., *LIMDD*, Quantum 7 (2023) 1108. -- Tutorial: Quantum Inf. Process. (2025), https://doi.org/10.1007/s11128-025-04917-0. - ---- - -### 4. (REVISED) Stabilizer-rank / sparsification refinements to CliffordRz - -**Correction.** `CliffordRz` is a stabilizer-rank simulator -- it represents states as sum of CH-form stabilizer states and cites Bravyi et al. (arXiv:1808.00128). Each RZ doubles the term count; norm computation uses CH-form inner products. See `docs/concepts/clifford-rz-simulator.md`. - -**Open research directions** (things CliffordRz may not already cover): - -- **Sparsification / random stabilizer decomposition.** Bravyi-Smith-Smolin style *sampling* from the sum rather than carrying all 2^t terms -- runtime scales with *stabilizer extent* / *robustness of magic*, not 2^t. -- **Low-extent magic state decompositions.** Replace per-RZ doubling with structured multi-T decompositions (|T> Pauli-rotation IR -> lattice surgery ops + visualizer. -- PennyLane has a PBC compilation module. - ---- - -### 6. Bosonic / continuous-variable simulators (GKP, cat, binomial codes) - -**What it is.** Fock-truncated or phase-space (Wigner, Husimi) simulation of bosonic modes with Gaussian + non-Gaussian operations. - -**Why QEC needs it.** GKP codes, cat codes, binomial codes, dual-rail, concatenated bosonic-qubit codes. Increasingly central to neutral-atom / superconducting bosonic / photonic QEC. PECOS is qubit-only. - -**PECOS status.** Not present. - -**Seminal refs.** -- Gottesman, Kitaev, Preskill, *Encoding a qubit in an oscillator*, PRA 64 (2001). -- Mirrahimi et al., *Dynamically protected cat-qubits*, NJP 16 (2014). -- Michael et al., *New Class of Quantum Error-Correcting Codes for a Bosonic Mode*, PRX 6 (2016). - -**Existing OSS.** -- Bosonic Qiskit (C2QA / IBM-NQI) -- qumode + qubit hybrid circuits: https://github.com/C2QA/bosonic-qiskit -- Mr Mustard (Xanadu) -- differentiable Gaussian + Fock, phase-space <-> Fock bridge: https://github.com/XanaduAI/MrMustard -- Dynamiqs -- JAX-based GPU Lindblad / SME solvers; used by Alice & Bob for cat-qubit chips: https://github.com/dynamiqs/dynamiqs -- Strawberry Fields (Xanadu, photonic CV). -- `EQuS/bosonic` -- deprecated, now `jaxquantum.circuits` / `jaxquantum.codes` (2025-07-13). -- Piquasso (photonic QC platform, Quantum 2025). - -**Newer ref worth tracking.** -- *Bosonic Pauli+*: efficient simulation of concatenated GKP codes, arXiv:2402.09333. -- *Classical simulation of circuits with realistic odd-dimensional GKP states*, arXiv:2412.13136. -- *Fast simulation of bosonic qubits via Gaussian functions in phase space*, PRX Quantum 2 040315 (2021). -- *Universal gate set for GKP logical qubits*, Nat. Phys. (2025). - ---- - -### 7. Lindblad / master-equation + quantum-trajectory simulators - -**Design doc:** `design/lindblad_sim_skeleton.md` (2026-04-12). - -**What it is.** Continuous-time evolution under Lindbladians, optionally unraveled as stochastic quantum trajectories (Monte Carlo wavefunction / quantum jumps). - -**Why QEC needs it.** Realistic noise: T1/T2, coherent errors, leakage, crosstalk, cross-resonance dynamics; non-Markovian extensions; studying Pauli-twirl approximation error; modeling syndrome extraction in the analog regime. **The wedge:** no mainline OSS (QuTiP, Dynamiqs, QuantumToolbox.jl) exposes `Lindbladian + gate_duration -> effective Pauli-Lindblad rates`. arXiv:2502.03462 defines this algorithm (Magnus/Dyson on superoperator, then Pauli-twirl). - -**PECOS status (audit 2026-04-12).** `exp/pecos-neo/` has sample-only `NoiseChannel` trait (`src/noise.rs:607`); `NoiseResponse` is a Pauli-injection enum. Time only on `NoiseEvent::IdleTime` -- `AfterGate` lacks a `duration` field. No Kraus/CPTP infrastructure, no continuous-time solver. Clean gap. - -**Seminal refs.** -- Dalibard, Castin, Molmer (1992) [MCWF]. -- Plenio, Knight (1998) [review]. -- Modern: Johansson, Nation, Nori, *QuTiP* (2012/2013). - -**Existing OSS.** -- QuTiP (Python) -- reference implementation, `mesolve` / `mcsolve`. -- Dynamiqs (JAX, GPU-accelerated, differentiable) -- 30-60x speedup on dissipative cat CNOT: https://github.com/dynamiqs/dynamiqs -- QuantumToolbox.jl (Julia, QuTiP-like syntax, distributed + GPU): https://github.com/qutip/QuantumToolbox.jl -- arXiv:2504.21440. -- C3 (characterization / control / calibration framework). - -**Newer ref worth tracking.** -- Lambert et al., *QuantumToolbox.jl* (2025), arXiv:2504.21440. -- Malekakhlagh et al., *Efficient Lindblad synthesis for noise model construction*, npj QI 11 (2025), arXiv:2502.03462 -- **key bridge paper**. Magnus-on-superoperator in interaction frame + Pauli-twirl gives diagonal Pauli-Lindblad generator. No public code. Defines the `Gate -> PauliLindbladModel` API PECOS needs. -- Pichler & Zoller et al. / arXiv:2407.03576 -- 4th-order commutator-free Magnus in Liouville space (gold-standard cross-check for effective-generator synthesis). -- arXiv:2402.16727 -- *Pauli approximation can underestimate logical failure rate* for 5-qubit code under realistic Lindblad; warns twirl is not free. -- arXiv:2510.23797 -- coherent DEMs have hyperedges that vanish under Pauli twirl; motivates path (b) trajectory -> learned DEM as validator. -- Daley 2014 (Adv. Phys.) -- canonical MCWF review; no post-2020 replacement. -- arXiv:2306.14876 -- pseudo-Lindblad trajectories for non-GKSL (opt-in, post-v1). - -**Reference implementations (scout 2026-04-12).** -- QuTiP: `mesolve` default `"adams"` (zvode), `mcsolve` uses bisection for jump times. -- Dynamiqs (JAX/GPU): `Tsit5/Dopri5/Dopri8` + `jax.vmap+jit` for trajectory batching -- source of its ~30x dissipative-cat-CNOT speedup. -- QuantumToolbox.jl: `DP5()` default via OrdinaryDiffEq; `EnsembleThreads` for trajectories. Closest architectural template for PECOS. -- None expose `Lindbladian + duration -> Pauli rates`. - ---- - -### 8. Fermion-native simulators (no Jordan-Wigner cost) - -**What it is.** Second-quantized fermion operators simulated directly (matrix-product-fermion states, Gaussian fermion + low-rank non-Gaussian, etc.) without qubit mapping overhead. - -**Why QEC needs it.** Fermionic codes (Majorana fermion code, Bravyi-Kitaev-style fermionic LDPC), QEC for fermionic simulation itself (fault-tolerant chemistry), tensor-network methods on fermionic Hilbert spaces. - -**PECOS status.** Not present. - -**Anchor refs.** -- Bravyi, Kitaev, *Fermionic Quantum Computation*, Ann. Phys. 298 (2002). -- Corboz, Vidal, *Fermionic multiscale entanglement renormalization ansatz* (2009). - -**Existing OSS.** OpenFermion (operator-level, not fast sim), ITensor fermionic MPS, TeNPy. - ---- - -### 9. Correlated / Pauli-Lindblad noise model simulators - -**What it is.** Circuit-level noise with correlated (multi-qubit) Pauli-Lindblad generators, learned from device tomography (IBM's PEC/PEA pipeline). Not pure iid depolarizing. - -**Why QEC needs it.** Accurate threshold / pseudo-threshold estimates on real hardware; studying impact of correlations on matching decoders; PEC-assisted QEC experiments. - -**PECOS status.** `pecos-neo` supports crosstalk/leakage channels (good start); unclear if Pauli-Lindblad learned models are a first-class input. TODO: verify with `pecos-neo` docs. - -**Seminal refs.** -- van den Berg, Minev, Kandala, Temme, *Probabilistic error cancellation with sparse Pauli-Lindblad models*, Nat. Phys. 19 (2023). arXiv:2201.09866. -- Cai et al., *Quantum error mitigation*, RMP (2023). - -**Newer refs worth tracking.** -- Chen et al., *Techniques for learning sparse Pauli-Lindblad noise models*, Quantum 8 (2024), DOI 10.22331/q-2024-12-10-1556. arXiv:2311.15408. -- *Efficient Lindblad synthesis for noise model construction*, npj QI (2025), arXiv:2502.03462. -- *Bayesian inference of general noise-model parameters from surface-code syndrome statistics*, arXiv:2406.08981 (couples learned noise -> DEM-style decoder input). - ---- - -### 10. Weak-simulation samplers via quasi-probability / negativity - -**What it is.** Sample measurement outcomes of near-Clifford circuits via quasi-probability decompositions (Wigner negativity, Howard-Campbell robustness of magic). Runtime scales with negativity/robustness, not 2^n. - -**Why QEC needs it.** Resource-theoretic analysis of magic injection, distillation cost lower bounds, benchmarking distillation protocols. - -**PECOS status.** Not present. - -**Anchor refs.** -- Pashayan, Wallman, Bartlett, *Estimating outcome probabilities of quantum circuits using quasiprobabilities*, PRL 115 (2015). -- Howard, Campbell, *Application of a Resource Theory for Magic States to Fault-Tolerant Quantum Computing*, PRL 118 (2017). - ---- - -### 11. Fusion-based / measurement-based photonic QEC sims - -**What it is.** Discrete-variable photonic FBQC / MBQC: cluster-state construction via fusion gates, loss + dephasing noise, percolation-threshold analysis. - -**Why QEC needs it.** PsiQuantum-style FBQC, measurement-based surface codes, photonic interfaces. PECOS `GraphStateSim` has the states but not the fusion/loss sim layer. - -**Anchor refs.** -- Bartolucci et al. (PsiQuantum), *Fusion-based quantum computation*, Nat. Commun. 14 (2023). -- Raussendorf, Harrington, Goyal, *A fault-tolerant one-way quantum computer*, Ann. Phys. 321 (2006). - ---- - -## Ranking (grug's revised first-cut opinion) - -Given PECOS already has DemSampler, CliffordRz, STN/MAST, pecos-neo: - -1. **DemStabSim** (new module; wraps existing DemSampler/influence-map as a first-class backend via `sim()`) -- see proposal below. Build first. -2. **Lindblad / trajectory** (#7) -- only honest way to study coherent / non-Pauli noise; feeds DemStabSim via channel->Pauli-rate lowering (arXiv:2502.03462). Build second. -3. **Pauli-Lindblad correlated noise -> DEM** (#9) -- learned IBM-style noise as a DemStabSim input; small addition once #1 lands. -4. **CliffordRz sparsification** (revised #4) -- confirmed absent; standalone refinement, do when researcher hits the 2^t wall. -5. **Pauli-based computation** (#5) -- matches FTQC resource accounting; pairs with MAST. - -**Out of scope.** Bosonic / CV (#6), photonic FBQC (#11) -- PECOS does not work on these areas. - -**Rest** (matchgate, decision diagrams, fermion-native, quasiprobability) are narrower or more research-y and not on the near-term path. - ---- - -## Proposal: DemSampler-backed "fast stabilizer + depolarizing" simulator - -**Goal.** Expose the existing DemSampler / fault-influence-map machinery as a **first-class simulator** alongside `SparseStab`, `CliffordRz`, `StateVec`, etc. Stim is inspiration only -- PECOS stays self-contained. - -**What it gives the user.** A drop-in sim for the most common QEC research workload: Clifford circuit + per-location depolarizing-family noise -> detector + observable + raw-measurement samples at Stim-competitive speeds. Reuses every piece PECOS already has (`DagFaultAnalyzer`, `DemBuilder`, `DemSamplerBuilder`, `NoisySampler`) instead of adding a new algorithm. - -### Why this is a real simulator, not just sugar - -Stim's core algorithm *is* "Pauli-frame propagation through a Clifford circuit with per-location Pauli noise, aggregated into detector/observable signatures, then sampled shot-wise". That is exactly what PECOS's fault-influence + DemSampler pipeline does today. Wrapping it behind a simulator-shaped API makes the equivalence visible and reusable. Calling it what it is also keeps the story honest: it is a Clifford + Pauli-noise sim, not a general sim. - -### Proposed location and name - -- Crate: **`pecos-simulators`** (same place as `SparseStab`, `StateVec`). -- Module: `src/dem_stab.rs` (or `fault_influence_sim.rs`). -- Public type: `DemStabSim` (bikeshed: `InfluenceSampler`, `FaultFrameSim`). - -### SimBuilder audit (2026-04-11) - -Findings from `crates/pecos-engines/src/sim_builder.rs` and `python/pecos-rslib/src/sim.rs`: - -**Rust shape.** `SimBuilder` holds four pieces: `classical_builder` (required), `quantum_builder` (default `SparseStabEngine`), `noise_builder` (default `PassThroughNoiseModel`), `config`. Backend registration convention is a free function returning a builder: - -```rust -.quantum(sparse_stab()) // IntoQuantumEngineBuilder -.quantum(state_vector()) // same pattern -.noise(DepolarizingNoise { p: 0.001 }) // IntoNoiseModel -``` - -**`QuantumEngine` trait is streaming.** It's a `process(ByteMessage) -> ByteMessage` interface driven per-tick by the classical engine, with the noise model intercepting `ByteMessage`s before they hit the quantum side. This is a fundamental fit-shape constraint for DemStabSim. - -**Python shape.** `sim(program)` dispatches on program type (QASM / QIS / HUGR / PHIR) and each variant carries a `quantum_engine_builder: Option<...>` slot -- same backend-selection pattern. - -### Implication: two honest integration paths - -Because `QuantumEngine` is streaming and DemStabSim is batch-by-nature, grug sees two options: - -**Path A -- Record-and-replay `QuantumEngine` impl (recommended first step).** -`DemStabSimEngine` implements `QuantumEngine` by buffering all incoming `ByteMessage`s into an internal `DagCircuit`. On the first "end of circuit" signal (or lazy on first measurement query), it runs `DagFaultAnalyzer` -> `DemSamplerBuilder::build` once and caches the sampler. Subsequent shots short-circuit via `DemSampler::sample_batch`. Zero orchestrator changes; slots straight into `sim(program).quantum(dem_stab()).noise(...)`. - -Hard limitation: **only valid for non-adaptive circuits** (no classical feed-forward affecting gate sequence across shots). That is fine for static syndrome-extraction memory experiments, which is most standard QEC research. DemStabSim must *reject* circuits where the ByteMessage stream depends on mid-circuit measurement outcomes, and clearly redirect users to `sparse_stab()` + `pecos-neo` for adaptive circuits. - -**Path B -- Batch-mode fast-path (confirmed on roadmap, after Path A).** -Extend `SimBuilder` with a batch-execution branch that, when a batch-capable backend is set, bypasses the per-shot classical loop entirely and hands the whole compiled program to the backend once. More invasive, semantically honest, unlocks GPU batch. Both paths are on the roadmap: **Path A first** (record-and-replay inside the streaming `QuantumEngine` shape) to land the backend with minimal orchestrator churn, **Path B second** once Path A proves the numbers so the orchestrator surgery is paid for by real speedups. - -Action items: -- [ ] Confirm how end-of-shot is signalled to `QuantumEngine` today (look for `reset()` / shot-boundary markers in `ByteMessage`). -- [ ] Confirm DemSampler cache can be safely reused across `MonteCarloEngine::run()` calls with fresh RNG (should be yes). -- [ ] Decide rejection mechanics: return `PecosError::Input` on first classical-feedback instruction, or pre-scan once at build. - -### Integration with the `sim()` entry point - -`sim()` is the main simulation entry on both sides: - -- Rust: `crates/pecos-engines/src/sim_builder.rs:418` -- `pub fn sim(input: I) -> SimBuilder`. -- Python: `python/pecos-rslib/src/sim.rs:66` -- `pub fn sim(py, program) -> PySimBuilder`. - -DemStabSim must be selectable through `sim(circuit).backend(...)` / equivalent, not live as a sidecar API. Concretely: - -- Register `DemStabSim` as a backend variant in whatever enum / dispatch `SimBuilder` uses today (check `engine_builder::SimInput` and existing backends like `SparseStab`, `StateVec`). -- `sim(dag).dem_stab().noise(...).detectors(...).sample(n)` reads naturally at both call sites. -- The builder path is the ergonomic home for the noise-model hierarchy and detector/observable definitions. -- Python mirror: `pecos.sim(program).dem_stab().noise(...).sample(n)` via PyO3 bindings in `pecos-rslib`. - -**Action item.** Audit `SimBuilder` / `PySimBuilder` to confirm the shape of the backend-selection API before committing to a method name, so DemStabSim slots in next to existing backends consistently. - -### Two API shapes (offer both) - -#### Shape A -- batch / circuit-at-a-time (primary, honest API) - -Takes a fully-specified `DagCircuit` (or `TickCircuit`) + noise model + detector/observable definitions, returns batch shot results. This is the *true* shape of the algorithm; no per-gate illusion. - -```rust -let mut sim = DemStabSim::builder() - .circuit(&dag) - .noise(DepolarizingModel::uniform(p = 1e-3)) // or PauliLindblad, per-location, ... - .detectors(&detectors) - .observables(&observables) - .build()?; - -let shots = sim.sample_batch(num_shots, &mut rng); -// shots: { detector_flips, observable_flips, [optional] raw_measurement_record } -``` - -Internally: `DagFaultAnalyzer -> DagFaultInfluenceMap -> DemSamplerBuilder -> DemSampler::sample_batch`. - -#### Shape B -- `CliffordGateable` facade (compat shim) - -A thin record-and-replay wrapper that implements `CliffordGateable` / `QuantumSimulator`. Gate calls append to an internal `DagCircuit`. First measurement / `end_shot` / explicit `.finalize()` triggers one-time influence-map build; subsequent shots reuse the cached analysis. - -```rust -let mut sim = DemStabSimFacade::new(n_qubits) - .with_noise(DepolarizingModel::uniform(1e-3)); - -sim.h(&[q0]).cx(&[(q0, q1)]).mz(&[q0, q1]); // records -let result = sim.run_shot(&mut rng); // builds influence map lazily -``` - -Trade-off: per-gate method-chain is *not* cheap here (allocates into DAG). Document clearly: "prefer Shape A; Shape B exists only for trait-compatibility with code that assumes a streaming sim". - -### Noise model input - -Not locked to depolarizing. Start simple, extend via traits: - -- `UniformNoiseModel::depolarizing(p)` (already exists). -- `PerLocationNoiseModel { cx: (px, py, pz, pxx, ...), mz: p_flip, idle: (t1, t2 + tick_duration), ... }`. -- `PauliLindbladNoiseModel { generators: &[(support, rate)] }` -- maps learned IBM-style sparse Pauli-Lindblad to per-location effective Pauli rates; covers correlated noise. (See arXiv:2201.09866, 2311.15408.) -- `FromChannelOp(ChannelMatrix)` -- lowers an arbitrary CPTP Pauli-twirled channel to rates; rejects non-Pauli parts with a warning (keeps honest). -- Future: `FromLindblad(LindbladOp, gate_duration)` -- feeds a trajectory/exp-midpoint solver (item #7) to produce the Pauli channel per location. - -### Outputs - -- Detector flips (`Vec` per shot or bit-packed `PackedBits`). -- Observable flips. -- Optional: raw measurement record (toggleable via `MemBuilder` / measurement-noise-model path already present). -- Sampling statistics (already exposed via `SamplingStatistics`). -- Circuit-level Pauli error record per shot (useful for decoder dev / syndrome studies) -- TODO: confirm whether `NoisySampler::ShotResult::faults_fired` is exposed or internal. - -### Where PECOS should deliberately differ from Stim - -Stim is the inspiration; these are places to diverge on purpose: - -1. **First-class DAG / `TickCircuit` ingestion** -- no text round-trip, no external IR. PECOS's circuit types are the canonical input. -2. **No text DEM format as the API boundary.** Expose `DetectorErrorModel` (typed Rust) directly; string form is a serialization detail. -3. **Richer noise model hierarchy.** Pauli-Lindblad / channel / Lindblad-derived inputs as above, with clean trait plumbing instead of Stim's circuit-instruction-annotation-only model. -4. **Native hybrid escape hatch.** When the circuit has T / RZ / RX / ... gates outside the Clifford subgroup, either (a) refuse and suggest `CliffordRz` / STN / MAST, or (b) fall back to `CliffordRz`-driven DEM generation for those slices. Not a Stim feature. -5. **GPU path.** `pecos-gpu-sims` already has wgpu; DemSampler sampling is embarrassingly parallel (independent shots, independent mechanisms per shot). A wgpu backend for the batch sampler is natural. -6. **Tighter decoder handoff.** PECOS controls its own decoder stack, so the DEM type can carry extra metadata (detector spacetime coords, hypergraph decomposition hints) without standard-format constraints. - -### Implementation plan - -1. New module `pecos-simulators/src/dem_stab.rs`. -2. Re-export `DemStabSim` (Shape A) from `pecos-simulators` prelude. -3. Implement `QuantumSimulator` on a facade type `DemStabSimFacade` (Shape B) with internal `DagCircuit` accumulator. -4. Parity tests: Clifford + depolarizing circuit on `SparseStab + pecos-neo noise + Monte Carlo` vs `DemStabSim` (with and without statistical `compare_dems_statistical`) -- distributions must match. -5. Micro-benchmarks vs direct stabilizer Monte Carlo (expect large speedup once shots > ~100). -6. Python bindings through `pecos-rslib` (follow the `DemSamplerBuilder` existing path). -7. Docs: `docs/concepts/dem-stabilizer-simulator.md` explaining the algorithm and the Stim parallel explicitly. - -### Open questions - -- [ ] Name: `DemStabSim` vs `InfluenceSampler` vs `FaultFrameSim`. (Grug prefers names that say what it is; `DemStabSim` is fine.) -- [ ] Should Shape B exist at all, or is documentation + Shape A enough? (Grug lean: skip Shape B until a concrete consumer asks. Record-and-replay smells.) -- [ ] Per-shot raw measurement record: always on (matches Stim) or opt-in (memory cost)? Default off, opt-in. -- [ ] Seeding semantics when shots run in parallel (`rayon`): use per-shot seed derived from master seed (deterministic, embarrassingly parallel) vs thread-local split. - ---- - -## Build order - -**Confirmed build order (2026-04-11):** - -1. **DemStabSim first.** Wraps existing infrastructure, slots into `sim()` as a new backend, highest near-term leverage for QEC research. No new algorithmic risk. -2. **Lindblad + quantum-trajectory second.** Closes the device-characterization -> effective-Pauli-channel -> DemStabSim loop. Anchored to `pecos-neo`. - -Out of scope for this roadmap (per project direction, 2026-04-11): **photonic / fusion-based**, **GKP / cat / bosonic codes**. Sections #6 and #11 remain documented for completeness but are not proposals. - -## Next simulator proposal (after DemStabSim) - -Given the current stack, grug recommend **open-system / Lindblad + quantum-trajectory simulator** as the next build, for these reasons: - -1. **Bridges device physics to PECOS's existing DEM pipeline.** Efficient-Lindblad-synthesis techniques (arXiv:2502.03462) lower a per-gate Lindbladian to an effective Pauli channel per location, which feeds straight into the `DemStabSim` noise-model input above. This turns every real-device characterization run into a honest PECOS noise model. -2. **Only way to study coherent / non-Pauli errors honestly.** Pauli-twirling assumptions underlie every stabilizer-based sim; a trajectory sim is the validator. -3. **Leverages existing `pecos-neo` scaffolding.** `pecos-neo` already has composable channels and Monte Carlo parallel execution -- a Lindblad / MCWF solver slots in as a new channel-evaluation backend. -4. **Narrow, well-understood scope.** QuTiP, Dynamiqs, QuantumToolbox.jl are mature references; algorithm risk is low, the gain is PECOS-native performance + tight coupling with DEM generation. -5. **Practical leverage right now.** Researchers using PECOS on near-term hardware benchmarks pay a lot for Pauli-twirled approximations when what they actually want is "what does this T1/T2/over-rotation budget imply for my logical error rate". This closes that loop. - -Bosonic / CV and photonic FBQC are **out of scope** for the PECOS roadmap and are not candidates here. - -Concrete next steps (separate design doc): -- Pick solver family (adaptive RK vs Magnus vs Krylov exp) for mid-size (N <= 10 qubits) Lindbladians. -- Define `LindbladOp` + `TrajectoryResult` types. -- Bridge API: `LindbladBackend::gate_channel(op, duration) -> PauliChannel` for DemStabSim consumption. -- Trajectory mode (MCWF / quantum jumps) for variance-reduced sampling. -- GPU path: start with rayon-parallel trajectories on CPU; wgpu later if cost justifies. - -## TODOs before formalizing - -- [x] Confirm `PauliProp` does not already extract DEMs -- correction: `pecos-qec::fault_tolerance::dem_builder` already does. -- [x] Audit CliffordRz for sparsification -- none present. -- [ ] Verify `pecos-neo` scope in detail (Pauli-Lindblad learned input format? continuous-time?). -- [ ] Check `STN/MAST` docs on `study/tensor-network-clifford-rz` for overlap with stabilizer-rank sampling (may already cover some of the CliffordRz refinements). -- [ ] Ask maintainer which roadmap items (if any) already claim Lindblad / bosonic / PBC. -- [ ] Add OSS licence notes per wrapper candidate (Dynamiqs: Apache-2.0? Bosonic Qiskit: Apache-2.0? Stim: Apache-2.0; confirm). diff --git a/design/stab_sample_orchestration.md b/design/stab_sample_orchestration.md deleted file mode 100644 index f96e20879..000000000 --- a/design/stab_sample_orchestration.md +++ /dev/null @@ -1,267 +0,0 @@ -# `pecos.sampling.stab` -- Batch Orchestration for Static Stabilizer Sampling - -Status: draft / proposal -Pairs with: `design/qec_sim_literature.md`, `design/dem_stab_sim_skeleton.md` -Date: 2026-04-11 (revised same day) - -## Problem - -PECOS already has the two batch primitives we need: - -- `DemStabSim` (wraps `DemSampler`) -- samples detector + observable flips. -- `MemStabSim` (wraps `MeasurementNoiseModel`) -- samples raw measurement outcomes. - -Both expose `sample_batch(N, rng)` that computes the error mechanism table **once** and then draws N shots in a tight loop. `DemSampler` additionally has rayon-parallel fast paths (`sample_statistics`, `sample_statistics_parallel`) that scale across workers. - -The current main simulation entry, `sim()` in `pecos-engines`, is built on `MonteCarloEngine`: a per-shot classical-engine loop. Wrapping `DemStabSim` / `MemStabSim` behind the `QuantumEngine` streaming trait (the Path A record-and-replay idea in `dem_stab_sim_skeleton.md`) **throws away the batch win**: we would compute the mechanism table once and then re-enter the classical shot loop N times instead of calling `sample_batch(N)` once. - -That is not the right shape for the workload this is built for: - -- Circuits are **static** (no classical feed-forward / conditionals / loops). -- Noise is **Pauli-family** (depolarizing, per-location, later Pauli-Lindblad, later channel-lowered). -- The user wants **many shots, fast**, for threshold estimation / memory experiments / decoder benchmarking. - -## API architecture: top-level `sim()` plus `sampling.*` catalog - -Four options were considered: - -- **X1 -- single magic top-level.** `sim(anything)` dispatches internally. Rejected: magic hurts predictability. -- **X2 -- flat method-named top-level.** `monte_carlo()`, `dem_sampling()`, `subset_sampling()`, `importance_sampling()`. Rejected: puts "which method fits my problem" on the user; leaks implementation vocabulary. -- **X3 -- flat intent-named top-level.** `sim()`, `sample()`, `rare_events()`. Rejected: vague naming, multiple top entries still. -- **X4 -- one beginner hook + grouped submodule.** Chosen. - -**X4 in one line.** Keep `sim()` and `sim_neo()` as top-level shortcuts for the two most-used strategies; expose the full sampling catalog under a grouping module `pecos.sampling.*` that is IDE-tab-discoverable. - -### Why X4 wins - -- `sim()` is PECOS's brand entry. Breaking it buys nothing. -- Power users get honest explicit access under a grouping noun that tells the truth: these are **sampling strategies**, not "the sim function and its rivals". -- Submodule invites future entries (`sampling.matchgate`, `sampling.decision_diagram`, ...) without cluttering top-level namespace each time. -- Uses user-language word ("sampling"), not implementation-language word ("orchestrator"). - -### Two ways to call the same thing (aliases, not duplicates) - -`sim()` and `sim_neo()` stay top-level as shortcuts. Inside the catalog, the same strategies are available as re-exports -- one implementation, two paths to it: - -| User types | Resolves to | -|---|---| -| `pecos.sim(prog)` | monte-carlo over classical-engine loop | -| `pecos.sampling.monte_carlo(prog)` | **same** code as `sim(prog)` (re-export) | -| `pecos.sim_neo(input)` | pecos-neo tool-framework shot loop | -| `pecos.sampling.neo(input)` | **same** code as `sim_neo(input)` (re-export) | -| `pecos.sampling.stab(dag)` | **new** -- batch DEM/MNM one-shot sample | -| `pecos.sampling.subset(...)` | future | -| `pecos.sampling.importance(...)` | future | - -Not rival entry points. Same implementations, two surfaces: friendly shortcut + explicit catalog. - -### Graduation rule - -A catalog entry graduates to a top-level shortcut only when it's load-bearing enough that users hit it constantly. Current bar is set by `sim` (monte carlo) and `sim_neo` (adaptive / composable noise). If `sampling.stab` becomes as common in a year, promote to `sample_stab()` top-level then. Until it earns promotion, the catalog entry is enough. - -### Why not promote "orchestrator" to the top-level concept - -Grug considered making orchestration the unifying abstraction: `pecos::orchestrator::monte_carlo()`, `pecos::orchestrator::neo()`, `pecos::orchestrator::batch()`. Rejected: - -1. The three orchestrators are **genuinely different shapes**, not three instances of one pattern. MonteCarloEngine (per-shot, classical-driven, streaming), pecos-neo tool framework (per-shot, ECS, rayon, adaptive), batch sampler (no shot loop at all). Unifying under one trait becomes a tagged union with mostly-optional methods -- the abstraction doesn't save code, it just moves the switch statement. -2. **Zero duplication evidence** between pecos-neo and the proposed batch path. Let concrete duplication name the abstraction, not prediction. -3. **"Orchestrator" is implementation-language.** Users ask "how do I get shots" and "what sampling strategy fits my problem", not "which orchestrator runs it". Top-level entries stay named by behavior. - -If a real orchestrator abstraction earns its place later (concrete duplication shows up, a user asks to swap orchestrators), that's the moment to extract it -- not now. - -## `sampling` vs `orchestration` as a builder verb - -When a sampling strategy needs to be selected *inside* an existing entry (e.g. `sim_neo(prog).(strategy)`), the verb is `.sampling(...)`, not `.orchestration(...)`: - -```rust -sim_neo(prog) - .sampling(sampling::monte_carlo()) // default - .sampling(sampling::importance(config)) // alt - .sampling(sampling::subset(config)) // alt - .run() -``` - -Reasoning: - -- Inside `sim_neo`, the **orchestrator is singular** (pecos-neo's tool framework). What varies per call is the **sampling strategy** that plugs into it. The verb names the axis that changes. -- `sampling` is user-language (statistical choice); `orchestration` is implementation-language (execution mechanism). Users pick statistical strategy. -- Matches the catalog noun `pecos.sampling.*`. Same word for the same concept at both call sites. -- Reserves `.orchestrator(...)` for the day (if ever) when swapping orchestrators is a user-visible axis. - -## Decision - -Build a separate orchestration entry, sibling to `sim()`, living inside the `sampling` catalog: - -```rust -pub fn stab(dag: DagCircuit) -> sampling::stab::Builder -``` - -Called as `pecos::sampling::stab(dag).noise(...).shots(...).run()`. `sim()` / `sim_neo()` are untouched; they become catalog entries as re-exports (`sampling::monte_carlo`, `sampling::neo`). - -No retrofit of `MonteCarloEngine`. No record-and-replay through `QuantumEngine`. A clean, separate path that preserves batch semantics end-to-end. - -## Builder chain - -```rust -use pecos_qec::sampling; - -let result = sampling::stab(dag) - .noise(NoiseConfig::uniform(1e-3)) - .detectors(detectors) // optional -> DEM path - .observables(observables) // optional -> DEM path - .include_raw_measurements(true) // opt-in; default false - .shots(100_000) - .workers(8) // rayon; default 1 - .seed(42) - .run()?; -``` - -Methods: - -- `.noise(NoiseConfig)` -- uniform depolarizing rates. Future: accept any type implementing a `DemStabNoiseModel` trait (see `dem_stab_sim_skeleton.md`). -- `.detectors(Vec)` / `.observables(Vec)` -- if either is set, take the DEM path; otherwise take the MEM path. -- `.include_raw_measurements(bool)` -- always available in MEM path; additionally toggleable in DEM path (carries extra cost). -- `.shots(n)` -- required. -- `.workers(n)` -- rayon worker count. `workers(0)` or omitted -> single-threaded. Helper `.auto_workers()` -> `available_parallelism`. -- `.seed(u64)` -- master seed; split deterministically across workers. -- `.run()` -- consumes the builder, runs, returns `SampleResult`. - -## Dispatch rule - -``` -if detectors.is_empty() && observables.is_empty(): - use MemStabSim -> raw measurement outcomes only. -else: - use DemStabSim -> detector + observable flips (+ optionally raw measurements). -``` - -The user picks by what they register, not by naming a backend. This reads naturally and removes a spurious choice. - -## Result type - -```rust -// pecos_qec::sampling::stab::SampleResult -pub struct SampleResult { - /// Per-shot detector flip vectors. Present when detectors were registered. - pub detector_flips: Option>>, - /// Per-shot observable flip vectors. Present when observables were registered. - pub observable_flips: Option>>, - /// Per-shot raw measurement outcomes. Always present in MEM path; - /// present in DEM path iff `.include_raw_measurements(true)`. - pub raw_measurements: Option>>, - /// Metadata for reproducibility / debugging. - pub num_shots: usize, - pub num_mechanisms: usize, - pub seed: u64, -} -``` - -Follow-up helpers (optional, add as the need shows up): -- `.logical_error_rate(observable_id: usize) -> f64` -- `.detector_rates() -> Vec` -- `.to_shot_vec(...) -> ShotVec` for compat with consumers that expect the engines' shot format. - -## Static-only guarantee - -For v1 the input is `DagCircuit`. A `DagCircuit` is a pure gate graph -- it has no conditional-gate opcode, no classical predicate, no loop construct. So the type itself is the static guarantee; no extra traversal or rejection check is needed in v1. - -When v2 adds program-IR lowering (QASM / QIS / HUGR / PHIR -> DagCircuit), the lowering layer does the static check: reject on any classical predicate, classically-controlled gate, or loop that depends on measurement outcomes. Unconditional loops are fine and get unrolled. - -This keeps v1 honest (no pretend-check on a type that can't contain feedback) and v2 honest (check where it actually matters). - -## Parallelism - -Shots are embarrassingly parallel. Two options: - -1. **Leverage the existing `DemSampler::sample_statistics_parallel`.** Already there, already tested. For DEM path this is the single-call fast path. Downside: returns aggregated statistics rather than per-shot bit vectors. -2. **Roll our own rayon split.** Chunk N shots by worker count; each worker gets a seeded RNG split (e.g. `seed ^ worker_idx` or `SplitMix64`). Each worker loops `sample_into_packed` locally. Merge. - -Grug recommend: DEM path -> default to `sample_statistics_parallel` when the user asks only for *aggregate* outputs (rates, logical-error counts). When the user asks for per-shot bit vectors, fall back to rolled-rayon. MEM path -> rolled-rayon (MNM does not have a native parallel path yet; if it becomes a bottleneck, add one). - -Seeding: master seed -> `PecosRng::seed_from_u64(seed)`; split to `workers` child seeds via a deterministic mixer (`SplitMix64`, `seed_from_u64(worker_id)`, whichever matches PECOS convention). Reproducibility means same `(seed, workers, shots)` returns the same bytes. - -## Where it lives - -Module layout follows PECOS convention (`foo.rs` + sibling `foo/` directory, no `mod.rs`): - -``` -crates/pecos-qec/src/sampling.rs -- parent module, catalog root -crates/pecos-qec/src/sampling/stab.rs -- stab strategy (this work) -crates/pecos-qec/src/sampling/neo.rs -- re-export of sim_neo() (future) -crates/pecos-qec/src/sampling/monte_carlo.rs -- re-export of sim() (future) -``` - -Public names: - -- `pecos_qec::sampling::stab::stab(dag) -> Builder` -- entry free function. - Actually cleaner: `pecos_qec::sampling::stab(dag) -> stab::Builder` (the module name doubles as the function when there's one primary constructor). Implemented as: - ```rust - // in sampling.rs - pub mod stab; - pub use stab::sample as stab; // or inline: pub fn stab(dag) -> ... - ``` - Bikeshed -- decide at implementation time. -- `pecos_qec::sampling::stab::Builder` -- `pecos_qec::sampling::stab::SampleResult` -- `pecos_qec::sampling::stab::BuilderError` - -Metacrate re-export: `pecos::sampling::stab` via existing `pecos-qec` re-export path. - -Python bindings in `pecos-rslib` follow later (v1b / v2), once the Rust API is stable. - -## Relationship to `DemStabSim` / `MemStabSim` - -`sampling::stab()` is the **user-facing** orchestration. It is implemented on top of `DemStabSim` / `MemStabSim` without giving up direct access to them. - -Power users keep the lower-level APIs: - -```rust -use pecos_qec::DemStabSim; - -let sim = DemStabSim::builder().circuit(dag).noise(n).detectors(d).build()?; -let mut rng = SmallRng::seed_from_u64(seed); -let batch = sim.sample_batch(n_shots, &mut rng); -// ... introspect sim.sampler(), export DEM, etc. -``` - -`sampling::stab` is for "give me shots, now"; the typed sims are for "I need the sampler object for something else". - -## What this deliberately is not - -- Not an extension of `MonteCarloEngine`. Per-shot streaming is not the right fit and forcing it throws away the batch primitive. -- Not a replacement for `sim()`. Classical control + adaptive programs still go through `sim()` with `sparse_stab` + `pecos-neo` noise. Two entries, two computational models. -- Not a Stim rewrite. Naming is honest: "sample a stabilizer circuit statically with depolarizing-family noise". Stim's workflow is inspiration only; the entry point is PECOS-shaped. -- Not an abstraction-first design. If a higher layer above `sampling::stab()` and `sim()` turns out to be useful later, it earns that place once concrete duplication shows up. Not before. -- Not a promotion of "orchestrator" to a top-level concept. See the X4 reasoning above. - -## v1 deliverables - -1. `crates/pecos-qec/src/sampling.rs` + `crates/pecos-qec/src/sampling/stab.rs`: - - Free function `stab(dag) -> Builder`. - - `Builder` + chain. - - `SampleResult`. - - `BuilderError` (e.g. missing shots, missing noise, builder misuse). - - Dispatch logic: DEM vs MEM on detector/observable presence. - - Rayon parallel shot split; deterministic per-worker seed. -2. Re-exports in `pecos-qec/src/lib.rs`. -3. Integration test: distance-3 repetition code, 10k shots, both DEM and MEM paths, assert logical-error rate sits within binomial CI around the analytic expectation. -4. Doctest on the module header example. -5. Clippy clean. - -## v2+ ideas (not blocking v1) - -- **Catalog completeness**: add `sampling::monte_carlo` (alias to `sim()`) and `sampling::neo` (alias to `sim_neo()`) so the `pecos.sampling.*` namespace is a full catalog from day one. -- Accept program IRs (QASM / QIS / HUGR / PHIR) with static-check + lowering to `DagCircuit`. -- Accept `TickCircuit` directly. -- Streamed output API (`stream_batches(chunk_size)`). -- Richer result type: `SampleResult::logical_error_rate(observable)`, `detector_rates()`, `export_dem()`. -- PyO3 bindings for `sampling::stab` in `pecos-rslib`; Python helper `pecos.sampling.stab(dag, noise=..., detectors=..., shots=...)`. -- Noise-model trait hierarchy (see `dem_stab_sim_skeleton.md`: `Uniform`, `PerLocation`, `PauliLindblad`, `FromChannel`, eventually `FromLindblad`). -- GPU batch sampler (wgpu) once CPU numbers motivate it. -- Future sampling strategies: `sampling::subset`, `sampling::importance`, `sampling::rare_events`, ... each as its own submodule under `sampling/`. - -## Open questions - -- [ ] Exact free-function name: `sampling::stab(dag)` vs `sampling::stab::sample(dag)` vs `sampling::stab::new(dag)`. Decide at implementation. Grug lean `sampling::stab(dag)` -- one token, reads cleanly. -- [ ] Where does `sampling::neo` live? In `pecos-qec/src/sampling/neo.rs` as a re-export of the `pecos-neo` crate, or should `pecos-neo` itself expose the module path? Defer until `sampling::stab` lands; decide then. -- [ ] `sampling::monte_carlo` as an alias of `sim()` implies a dep from `pecos-qec` -> `pecos-engines`. Currently it's the other way. If keeping `pecos-qec` free of `pecos-engines`, the alias lives in the metacrate `pecos` instead. Likely the right answer. From b59e7dec9cc3d189292a5de19cbf5d376d62d856 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Thu, 16 Apr 2026 21:11:21 -0600 Subject: [PATCH 049/125] Remove design/ directory: all docs migrated to pecos-docs vault --- design/ENGINES_ARCHITECTURE.md | 1005 ----------------- design/OPERATOR_TYPE_SYSTEM.md | 275 ----- design/QIS_ARCHITECTURE.md | 646 ----------- design/STABILIZER_CODE_ARCHITECTURE.md | 166 --- design/circuit-representations.md | 346 ------ design/pecos-cuquantum-plan.md | 225 ---- design/proposals/byte_message_api_cleanup.md | 36 - design/proposals/slr-ast.md | 973 ---------------- design/proposals/slr-qubit-allocators.md | 730 ------------ ...on-classical-interpreter-suspected-bugs.md | 54 - design/rust-phir-classical-interpreter.md | 298 ----- 11 files changed, 4754 deletions(-) delete mode 100644 design/ENGINES_ARCHITECTURE.md delete mode 100644 design/OPERATOR_TYPE_SYSTEM.md delete mode 100644 design/QIS_ARCHITECTURE.md delete mode 100644 design/STABILIZER_CODE_ARCHITECTURE.md delete mode 100644 design/circuit-representations.md delete mode 100644 design/pecos-cuquantum-plan.md delete mode 100644 design/proposals/byte_message_api_cleanup.md delete mode 100644 design/proposals/slr-ast.md delete mode 100644 design/proposals/slr-qubit-allocators.md delete mode 100644 design/python-classical-interpreter-suspected-bugs.md delete mode 100644 design/rust-phir-classical-interpreter.md diff --git a/design/ENGINES_ARCHITECTURE.md b/design/ENGINES_ARCHITECTURE.md deleted file mode 100644 index 09e383866..000000000 --- a/design/ENGINES_ARCHITECTURE.md +++ /dev/null @@ -1,1005 +0,0 @@ -# Engines Architecture: Simulation Framework - -This document describes the architecture of the `pecos-engines` crate, which provides the simulation framework for PECOS. It explains how quantum programs are executed, how classical and quantum components interact, and how the system enables mid-circuit measurements with classical feedback. - -## Design Philosophy - -PECOS serves two complementary roles: - -**As a Framework** - A complete, extendable environment for studying QEC and hybrid quantum-classical computation. Users can plug in custom components (error models, decoders, machines) and run full simulations with the `sim()` API or `HybridEngine`. - -**As a Library** - A collection of well-designed, independent components that users can pick and choose for their own projects. Need just a fast stabilizer simulator? Use `pecos-simulators::SparseStab`. Need deterministic seeding? Use `pecos-core::derive_seed()`. The crates are designed to be useful standalone. - -``` -┌─────────────────────────────────────────────────────────────────┐ -│ PECOS as Framework │ -│ - sim(program).quantum(sparse_stab()).run(1000) │ -│ - HybridEngine with custom components │ -│ - Full QEC simulation pipelines │ -└─────────────────────────────────────────────────────────────────┘ - -┌─────────────────────────────────────────────────────────────────┐ -│ PECOS as Library (pick what you need) │ -│ │ -│ ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ │ -│ │ pecos-simulators │ │ pecos-core │ │ pecos-random │ │ -│ │ SparseStab │ │ QubitId │ │ PecosRng │ │ -│ │ StateVec │ │ derive_seed │ │ │ │ -│ │ Gateable │ │ GateType │ │ │ │ -│ └──────────────┘ └──────────────┘ └──────────────┘ │ -│ │ -│ ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ │ -│ │ pecos-gpu- │ │ pecos- │ │ pecos- │ │ -│ │ sims │ │ clifford- │ │ engines │ │ -│ │ GpuSampler │ │ gates │ │ ByteMessage │ │ -│ └──────────────┘ └──────────────┘ └──────────────┘ │ -└─────────────────────────────────────────────────────────────────┘ -``` - -This dual nature means: -- Researchers can quickly prototype QEC experiments using the framework -- Library authors can integrate specific PECOS components into their own tools -- The same battle-tested code serves both use cases - -## Overview - -The `pecos-engines` crate orchestrates quantum simulation through a layered architecture: - -1. **User API Layer** - `sim()` function and `SimBuilder` for configuration -2. **Parallelization Layer** - `MonteCarloEngine` for multi-shot execution -3. **Execution Layer** - `HybridEngine` for single-shot orchestration -4. **Component Layer** - Classical engines, quantum systems, and noise models - -``` -┌─────────────────────────────────────────────────────────────┐ -│ User API (sim_builder) │ -│ sim(program).quantum(sparse_stab()).noise(...).run(1000) │ -└────────────────────┬────────────────────────────────────────┘ - │ - ▼ - ┌──────────────────────┐ - │ MonteCarloEngine │ (parallel orchestration) - │ (num_workers, seed) │ - └──────────┬───────────┘ - │ - ┌──────────┴───────────┐ - │ (parallel workers) │ - ▼ ▼ - ┌──────────────────────────────────────────┐ - │ HybridEngine (per worker) │ - │ - Cloned with derived seed │ - │ - Reset between shots │ - └────────┬─────────────────────────────────┘ - │ - ┌─────────┴──────────┐ - │ │ - ▼ ▼ -┌────────────────┐ ┌──────────────────────┐ -│ ClassicalEngine│ │ QuantumSystem │ -│ │ │ ┌────────────────┐ │ -│ - generate_ │ │ │ NoiseModel │ │ -│ commands() │ │ │ (transforms │ │ -│ - handle_ │ │ │ operations) │ │ -│ measurements │ │ └───────┬────────┘ │ -│ - get_results()│ │ ▼ │ -└────────┬───────┘ │ ┌────────────────┐ │ - │ │ │ QuantumEngine │ │ - │ │ │ (StateVec or │ │ - │ │ │ SparseStab) │ │ - │ │ └────────────────┘ │ - │ └──────────────────────┘ - │ │ - └────ByteMessage─────┘ - (binary protocol) -``` - -## Core Concepts - -### The Engine Trait - -All components in the system implement the base `Engine` trait: - -```rust -pub trait Engine { - fn process(&mut self, input: Input) -> Result; - fn reset(&mut self) -> Result<()>; -} -``` - -This simple interface enables composition - engines can delegate to other engines. - -### Control Flow with EngineStage - -The `EngineStage` enum enables feedback loops between components: - -```rust -pub enum EngineStage { - NeedsProcessing(I), // "Send this input to the controlled engine" - Complete(O), // "Processing finished, here's the result" -} -``` - -This is used by `ControlEngine` implementations (like `ClassicalEngine` and `NoiseModel`) to orchestrate execution with another engine. - -### ByteMessage Protocol - -Components communicate using `ByteMessage`, a binary protocol for quantum commands and measurement results: - -```rust -// Commands from classical to quantum -ByteMessage: [H(0), CX(0,1), MZ(0), MZ(1)] - -// Results from quantum to classical -ByteMessage: [MZ(0)=1, MZ(1)=1] -``` - -This allows efficient batching of operations and decouples the classical and quantum components. - -## The Classical-Quantum Feedback Loop - -The key architectural feature is the **feedback loop** between classical and quantum components. This enables: - -- Mid-circuit measurements -- Classical control based on measurement outcomes -- Repeat-until-success protocols -- QEC syndrome decoding and correction - -### Single Shot Execution Flow - -Inside `HybridEngine::run_shot()`: - -``` -┌─────────────────┐ ┌─────────────────┐ -│ ClassicalEngine │ │ QuantumSystem │ -└────────┬────────┘ └────────┬────────┘ - │ │ - │ 1. start() │ - │ ─────────────────────────────────► │ - │ ByteMessage: [H(0), CX(0,1), MZ(0)]│ - │ │ - │ 2. process() → execute gates │ - │ │ - │ 3. measurement results │ - │ ◄───────────────────────────────── │ - │ ByteMessage: [MZ(0) = 1] │ - │ │ - │ 4. continue_processing() │ - │ // Decide next action based on │ - │ // measurement result │ - │ │ - │ 5. More commands (if needed) │ - │ ─────────────────────────────────► │ - │ ByteMessage: [X(1), MZ(1)] │ - │ │ - │ 6. process() │ - │ │ - │ 7. final measurements │ - │ ◄───────────────────────────────── │ - │ │ - │ 8. Complete(Shot) │ - ▼ ▼ -``` - -### The Loop in Code - -```rust -// Simplified HybridEngine::run_shot() -fn run_shot(&mut self) -> Result { - // Reset both engines for fresh shot - self.classical_engine.reset()?; - self.quantum_system.reset()?; - - // Start execution - classical engine generates first batch of commands - let mut stage = self.classical_engine.start()?; - - loop { - match stage { - EngineStage::NeedsProcessing(commands) => { - // Send commands to quantum system - let measurements = self.quantum_system.process(commands)?; - - // Classical engine processes measurements and decides next action - stage = self.classical_engine.continue_processing(measurements)?; - } - EngineStage::Complete(shot) => { - // Done - return results - return Ok(shot); - } - } - } -} -``` - -### Concrete Example: QasmEngine - -The `QasmEngine` is a good example to understand how the feedback loop works in practice. Consider this QASM program with conditional logic: - -```qasm -h q[0]; -measure q[0] -> c[0]; -if (c==1) x q[0]; -measure q[0] -> c[1]; -``` - -Here's exactly what happens: - -**Round 1 - Start:** -``` -QasmEngine.start() - └─ process_program_impl() - ├─ Process: h q[0] → add H gate to batch - └─ Process: measure q[0] → BREAK! Must wait for result - Return NeedsProcessing([H(0), MZ(0)]) -``` - -**Round 1 - Quantum System:** -``` -QuantumSystem.process([H(0), MZ(0)]) - ├─ NoiseModel transforms operations (maybe adds errors) - ├─ QuantumEngine executes H, then measures - └─ Return ByteMessage([MZ(0) = 1]) // measured |1⟩ -``` - -**Round 2 - Continue:** -``` -QasmEngine.continue_processing([MZ(0) = 1]) - ├─ handle_measurements(): store c[0] = 1 - └─ process_program_impl() - ├─ Process: if (c==1) x q[0] - │ └─ c[0] is 1, so add X gate to batch - └─ Process: measure q[0] → BREAK! - Return NeedsProcessing([X(0), MZ(0)]) -``` - -**Round 2 - Quantum System:** -``` -QuantumSystem.process([X(0), MZ(0)]) - ├─ Execute X gate (flips |1⟩ back to |0⟩) - └─ Return ByteMessage([MZ(0) = 0]) -``` - -**Round 3 - Finish:** -``` -QasmEngine.continue_processing([MZ(0) = 0]) - ├─ handle_measurements(): store c[1] = 0 - └─ process_program_impl() - └─ No more operations → Return Complete(Shot { c: [1, 0] }) -``` - -**Key insight:** QasmEngine breaks the batch on every measurement because: -1. The measurement result might be needed by the next operation (`if` statement) -2. It can't know the result until the quantum system actually measures -3. So it must pause, get the result, store it in classical registers, then continue - -This is what makes mid-circuit measurement possible - the classical engine is in control, asking for quantum operations in batches and making decisions based on results. - -### Why This Matters - -This architecture enables **adaptive quantum circuits** where the program flow depends on measurement outcomes: - -``` -Example: Repeat-until-success - -Round 1: - Classical: "Apply H, measure" - Quantum: executes, returns measurement = 0 - Classical: "Wrong outcome, try again" - -Round 2: - Classical: "Reset, apply H, measure" - Quantum: executes, returns measurement = 1 - Classical: "Success! Done." -``` - -Without this feedback loop, you'd need to know all operations upfront, making adaptive protocols impossible. - -## Component Details - -### ClassicalEngine Trait - -The classical engine controls program flow: - -```rust -pub trait ClassicalEngine { - /// Compile/prepare the program - fn compile(&mut self) -> Result<()>; - - /// Generate quantum commands to execute - fn generate_commands(&mut self) -> ByteMessage; - - /// Process measurement results from quantum system - fn handle_measurements(&mut self, measurements: ByteMessage); - - /// Get final results after execution completes - fn get_results(&self) -> Shot; - - /// Number of qubits needed - fn num_qubits(&self) -> usize; - - /// Reset for next shot - fn reset(&mut self) -> Result<()>; -} -``` - -Different classical engines implement different program formats: -- `QasmEngine` - OpenQASM circuits -- `QisEngine` - QIS/LLVM IR programs (via Helios) -- `HugrEngine` - HUGR graphs (via Guppy) - -### QuantumEngine Trait - -The quantum engine executes gates: - -```rust -pub trait QuantumEngine { - /// Process a batch of quantum commands, return measurement results - fn process(&mut self, commands: ByteMessage) -> ByteMessage; - - /// Set RNG seed for reproducibility - fn set_seed(&mut self, seed: u64); - - /// Reset quantum state - fn reset(&mut self); -} -``` - -Built-in implementations: -- `StateVecEngine` - Full state vector simulation (universal) -- `SparseStabEngine` - Stabilizer simulation (Clifford circuits only) - -### NoiseModel Trait - -Noise models transform operations before execution: - -```rust -pub trait NoiseModel: ControlEngine { - // Inherits from ControlEngine: - // - start(commands) -> EngineStage - // - continue_processing(measurements) -> EngineStage -} -``` - -The noise model sits between classical and quantum engines: - -``` -Classical → NoiseModel → QuantumEngine - ↑ - May add noise gates - May flip measurement results -``` - -Built-in noise models: -- `PassThroughNoiseModel` - No noise (default) -- `DepolarizingNoiseModel` - Depolarizing noise on gates -- `BiasedDepolarizingNoiseModel` - Gate noise + measurement errors -- `GeneralNoiseModel` - Customizable per-gate noise - -### QuantumSystem - -`QuantumSystem` combines a noise model and quantum engine. The noise model "wraps" the quantum engine and can transform operations before they reach the simulator: - -```rust -pub struct QuantumSystem { - noise_model: Box, - quantum_engine: Box, -} -``` - -**The flow through QuantumSystem:** - -``` - QuantumSystem -┌─────────────────────────────────────────────────────┐ -│ │ -│ ByteMessage: [H(0), CX(0,1), MZ(0)] │ -│ │ │ -│ ▼ │ -│ ┌─────────────────────────────────────────────┐ │ -│ │ NoiseModel │ │ -│ │ - May add depolarizing errors after gates │ │ -│ │ - May flip measurement outcomes │ │ -│ │ - Returns EngineStage::NeedsProcessing │ │ -│ │ with modified commands │ │ -│ └─────────────────┬───────────────────────────┘ │ -│ │ │ -│ [H(0), X(0), CX(0,1), Z(1), MZ(0)] │ -│ (original ops + injected errors) │ -│ │ │ -│ ▼ │ -│ ┌─────────────────────────────────────────────┐ │ -│ │ QuantumEngine │ │ -│ │ (StateVec or SparseStab) │ │ -│ │ - Executes all gates on quantum state │ │ -│ │ - Performs measurements │ │ -│ │ - Returns raw measurement results │ │ -│ └─────────────────┬───────────────────────────┘ │ -│ │ │ -│ ByteMessage: [MZ(0) = 1] │ -│ │ │ -│ ▼ │ -│ ┌─────────────────────────────────────────────┐ │ -│ │ NoiseModel (again) │ │ -│ │ - May flip measurement results │ │ -│ │ - Returns EngineStage::Complete │ │ -│ │ with final measurements │ │ -│ └─────────────────┬───────────────────────────┘ │ -│ │ │ -│ ByteMessage: [MZ(0) = 0] (flipped!) │ -│ │ │ -└────────────────────┼────────────────────────────────┘ - │ - ▼ - Back to ClassicalEngine -``` - -The NoiseModel is itself a `ControlEngine` - it can return `NeedsProcessing` to send modified commands to the quantum engine, and the loop continues until it returns `Complete`. This allows noise models to: -- Inject error gates before/after operations -- Transform gate parameters -- Flip measurement outcomes -- Add multiple rounds of noise injection if needed - -## Parallelization with MonteCarloEngine - -`MonteCarloEngine` distributes shots across worker threads: - -```rust -pub struct MonteCarloEngine { - /// Template engine (cloned for each worker) - template: HybridEngine, - - /// Number of parallel workers - num_workers: usize, - - /// Base seed for reproducibility - seed: u64, -} -``` - -### Execution Flow - -```rust -fn run(&mut self, num_shots: usize) -> Result { - // Distribute shots across workers - let shots_per_worker = num_shots / self.num_workers; - - // Parallel execution with rayon - let results: Vec = (0..self.num_workers) - .into_par_iter() - .flat_map(|worker_id| { - // Clone template with derived seed - let mut engine = self.template.clone(); - engine.set_seed(derive_seed(self.seed, worker_id)); - - // Run assigned shots - (0..shots_per_worker) - .map(|_| engine.run_shot()) - .collect::>() - }) - .collect(); - - Ok(ShotVec::from(results)) -} -``` - -### Seed Derivation for Reproducibility - -Seeds are derived deterministically to ensure reproducible results: - -``` -Base seed (42) - ├── Worker 0: derive_seed(42, 0) - │ ├── Classical: derive_seed(..., 0) - │ └── Quantum: derive_seed(..., 1) - │ ├── NoiseModel: derive_seed(..., 0) - │ └── QuantumEngine: derive_seed(..., 1) - ├── Worker 1: derive_seed(42, 1) - │ └── ... - ... -``` - -This ensures: -- Same seed always produces same results -- Different workers have uncorrelated random streams -- Different components have uncorrelated random streams - -## User API: sim() and SimBuilder - -The `sim()` function provides a fluent API for configuration: - -```rust -// Basic usage -let results = sim(my_program) - .quantum(sparse_stab()) - .run(1000)?; - -// With noise -let results = sim(my_program) - .quantum(state_vec()) - .noise(DepolarizingNoise { p: 0.01 }) - .seed(42) - .workers(4) - .run(10000)?; - -// Reusable engine -let mut engine = sim_builder() - .classical(qasm_engine().qasm("H q[0]; measure q[0] -> c[0];")) - .quantum(sparse_stab()) - .build()?; - -let batch1 = engine.run(1000)?; -let batch2 = engine.run(2000)?; // Reuse same engine -``` - -### SimBuilder Configuration - -| Method | Purpose | -|--------|---------| -| `.classical(builder)` | Set classical engine (program source) | -| `.quantum(builder)` | Set quantum simulator | -| `.noise(model)` | Set noise model | -| `.seed(u64)` | Set RNG seed for reproducibility | -| `.workers(n)` | Set number of parallel workers | -| `.build()` | Build reusable engine | -| `.run(shots)` | Build and run immediately | - -## Results: Shot and ShotVec - -### Shot - -A `Shot` represents results from a single execution: - -```rust -pub struct Shot { - /// Named results (e.g., "outcome" -> 1) - results: BTreeMap, -} - -pub enum Data { - U32(u32), - I64(i64), - F64(f64), - Bool(bool), - BitVec(BitVec), - Json(serde_json::Value), -} -``` - -### ShotVec - -A `ShotVec` aggregates results from multiple shots in columnar format: - -```rust -let results: ShotVec = engine.run(1000)?; - -// Access as columns -let outcomes: &[i64] = results.get_i64("outcome")?; -// outcomes = [0, 1, 1, 0, 1, ...] (1000 values) - -// Convert to HashMap -let map: HashMap> = results.to_map(); -``` - -## Crate Dependencies - -``` -pecos-engines (orchestration) - │ - ├── pecos-simulators - │ ├── StateVec (state vector simulator) - │ ├── SparseStab (stabilizer simulator) - │ └── CliffordGateable, ArbitraryRotationGateable traits - │ - ├── pecos-core - │ ├── QubitId (qubit identification) - │ ├── GateType, Gate (gate definitions) - │ ├── derive_seed() (deterministic seed derivation) - │ └── PecosError (error handling) - │ - ├── pecos-random - │ └── PecosRng (parallel-safe RNG) - │ - └── byte_message/ (internal module) - ├── message.rs (parsing/serialization) - ├── protocol.rs (binary format definitions) - └── builder.rs (message construction) - -pecos-qis-ffi (C ABI for external programs) - │ - ├── QIS-style exports (__quantum__qis__*) - ├── Runtime functions (__quantum__rt__*) - ├── Dynamic circuit support (___lazy_measure, etc.) - └── ExecutionContext (thread-local isolation) - -selene-plugins/ (simulator plugins) - │ - ├── pecos-selene-statevec - └── pecos-selene-stabilizer -``` - -## ByteMessage: Binary Protocol for FFI and Plugins - -The `ByteMessage` protocol is a cornerstone of PECOS's extensibility. Beyond decoupling internal components, it enables Foreign Function Interface (FFI) support and a plugin architecture. - -### Binary Format - -ByteMessage uses a 4-byte aligned binary format stored in `Vec`: - -```rust -pub struct ByteMessage { - data: Vec, // Binary format with 4-byte alignment - byte_len: usize, // Track actual byte length -} -``` - -**Message Structure:** -- **Batch Header (16 bytes):** Magic number (`0x50_45_43_53` = "PECS"), protocol version, flags, message count, total size -- **Per-Message:** Message header (8 bytes) + payload -- **Payload:** Gate operations with encoded qubit indices and floating-point parameters -- **Alignment:** All boundaries padded to 4-byte alignment for FFI safety using `bytemuck` - -### FFI Support (pecos-qis-ffi) - -The `pecos-qis-ffi` crate exports C ABI functions following QIS (Quantum Instruction Set) standards: - -```rust -// Gate operations exported with #[no_mangle] extern "C" -__quantum__qis__h__body(qubit: *mut Qubit) -__quantum__qis__cx__body(control: *mut Qubit, target: *mut Qubit) -__quantum__qis__rz__body(theta: f64, qubit: *mut Qubit) -__quantum__qis__mz__body(qubit: *mut Qubit, result: *mut Result) - -// Runtime functions -__quantum__rt__qubit_allocate() -> *mut Qubit -__quantum__rt__qubit_release(qubit: *mut Qubit) -``` - -**Dynamic Circuit Support:** - -For mid-circuit measurement with classical feedback across FFI: - -```rust -// Lazy measurement returns a future ID -___lazy_measure(qubit: i64) -> i64 - -// Blocks until measurement result is available -___read_future_bool(future_id: i64) -> bool - -// Control dynamic execution mode -pecos_enable_dynamic_mode() -pecos_disable_dynamic_mode() -``` - -Thread-local `ExecutionContext` enables per-execution isolation for parallel Monte Carlo simulations: - -```rust -pub struct ExecutionContext { - pub dynamic_mode_active: AtomicBool, - pub waiting_for_result: AtomicU64, - pub sync_state: Mutex, - pub measurement_results: Mutex>, -} -``` - -### Plugin Architecture (selene-plugins) - -Plugins implement the `SimulatorInterface` trait: - -```rust -pub trait SimulatorInterface { - fn shot_start(&mut self, shot_id: u64, seed: u64) -> Result<()>; - fn shot_end(&mut self) -> Result<()>; - fn rxy(&mut self, qubit: u64, theta: f64, phi: f64) -> Result<()>; - fn rz(&mut self, qubit: u64, theta: f64) -> Result<()>; - fn czz(&mut self, q1: u64, q2: u64) -> Result<()>; - fn measure(&mut self, qubit: u64) -> Result; - // ... additional gate methods -} -``` - -**Available Plugins:** -- `pecos-selene-statevec` - State vector simulator -- `pecos-selene-stabilizer` - Stabilizer simulator - -### Python Bindings - -ByteMessage is exposed to Python via `pecos-rslib`: - -```python -from pecos import ByteMessage - -# Build a message -builder = ByteMessage.quantum_operations_builder() -builder.h([0]) -builder.cx([(0, 1)]) -builder.mz([0]) -message = builder.build() - -# Parse operations -gates = message.parse_quantum_operations() # Returns list of dicts -raw = message.as_bytes() # Raw binary for network/storage -``` - -### Design Benefits - -The ByteMessage protocol provides: - -- **Decouples components** - Classical and quantum engines don't need to know about each other's internals -- **Enables batching** - Multiple operations sent in one message -- **FFI-safe** - 4-byte alignment and simple binary format works across language boundaries -- **Plugin extensibility** - New simulators can be added without modifying core code -- **Network-ready** - Messages can be serialized for distributed simulation -- **Python integration** - Full access to simulation infrastructure from Python - -## Key Design Decisions - -### Why ControlEngine Pattern? - -The `ControlEngine` pattern (start/continue_processing) enables: -- **Feedback loops** - Essential for mid-circuit measurements -- **Lazy evaluation** - Only generate commands as needed -- **State management** - Controller maintains state across rounds -- **Composability** - Controllers can wrap other engines (e.g., NoiseModel wraps QuantumEngine) - -### Why Clone-per-Worker? - -Each worker gets a clone of the `HybridEngine`: -- **Thread safety** - No shared mutable state between workers -- **Independence** - Workers can't interfere with each other -- **Simplicity** - No complex synchronization needed -- **Reproducibility** - Each worker has deterministic behavior - -## Example: QEC Simulation Flow - -Here's how the architecture supports a QEC simulation: - -``` -1. Classical engine: Generate data qubit initialization - → ByteMessage: [H(d0), H(d1), ...] - -2. Quantum system: Execute initialization - → ByteMessage: [] (no measurements) - -3. Classical engine: Generate syndrome extraction circuit - → ByteMessage: [CX(d0,a0), CX(d1,a0), ..., MZ(a0), MZ(a1), ...] - -4. Quantum system: Execute, return syndrome measurements - → ByteMessage: [MZ(a0)=1, MZ(a1)=0, ...] - -5. Classical engine: Decode syndrome, generate corrections - → ByteMessage: [X(d0), Z(d2)] // Corrections based on decoder - -6. Quantum system: Apply corrections - → ByteMessage: [] - -7. Classical engine: Generate next round or final measurements - → ... - -8. Complete: Return Shot with logical measurement results -``` - -The feedback loop is essential here - the corrections depend on the syndrome measurements. - -## Python Extensibility - -PECOS is designed for Python users to write custom components while leveraging Rust performance for the heavy lifting. - -### Protocol-Based Architecture - -Python components implement Protocol classes (structural typing): - -```python -from __future__ import annotations - -from typing import Any, Callable, Protocol - -BitArray = Any # placeholder for bit-array type -Correction = Any # placeholder for correction type - - -class MachineProtocol(Protocol): - """Interface for hardware models (connectivity, leakage, etc.).""" - - leaked_qubits: set[int] - lost_qubits: set[int] - - def process(self, op_buffer: list) -> list: ... - - -class ErrorModelProtocol(Protocol): - """Interface for custom error/noise models.""" - - error_params: dict - - def init(self, num_qubits: int, machine: MachineProtocol | None = None) -> None: ... - def process(self, qops: list, call_back: Callable | None = None) -> list | None: ... - def reset(self) -> None: ... - - -class Decoder(Protocol): - """Interface for QEC decoders.""" - - def decode(self, syndrome: BitArray) -> Correction: ... -``` - -### Writing Custom Components in Python - -Users can implement any protocol in pure Python: - -```python -import random - - -class MyCustomErrorModel: - """Custom error model - just implement the protocol methods.""" - - def __init__(self, error_rate: float): - self.error_params = {"p": error_rate} - self.num_qubits = None - - def init(self, num_qubits: int, machine=None) -> None: - self.num_qubits = num_qubits - - def process(self, qops: list, call_back=None) -> list: - noisy_ops = [] - for op in qops: - noisy_ops.append(op) - if random.random() < self.error_params["p"]: - noisy_ops.append(("X", op)) # simplified noise - return noisy_ops - - def reset(self) -> None: - pass - - -model = MyCustomErrorModel(0.01) -model.init(num_qubits=5) -``` - -Usage with the hybrid engine: - -```hidden-python -import random - -from pecos.engines import HybridEngine - - -class MyCustomErrorModel: - def __init__(self, error_rate): - self.error_params = {"p": error_rate} - self.num_qubits = None - - def init(self, num_qubits, machine=None): - self.num_qubits = num_qubits - - def process(self, qops, call_back=None): - noisy_ops = [] - for op in qops: - noisy_ops.append(op) - return noisy_ops - - def reset(self): - pass - - def shot_reinit(self): - pass - - -program = { - "format": "PHIR/JSON", - "version": "0.1.0", - "metadata": {"num_qubits": 2}, - "ops": [ - {"data": "qvar_define", "data_type": "qubits", "variable": "q", "size": 2}, - {"data": "cvar_define", "data_type": "i32", "variable": "m", "size": 2}, - {"qop": "H", "args": [["q", 0]]}, - {"qop": "CX", "args": [[["q", 0], ["q", 1]]]}, - {"qop": "Measure", "args": [["q", 0]], "returns": [["m", 0]]}, - {"qop": "Measure", "args": [["q", 1]], "returns": [["m", 1]]}, - ], -} -``` - -```python -from pecos.engines import HybridEngine - -# Use with HybridEngine -engine = HybridEngine( - error_model=MyCustomErrorModel(0.01), # Python error model (flexible) -) -results = engine.run(program, shots=100) -``` - -### Two-Layer Architecture - -``` -┌─────────────────────────────────────────────────────────────┐ -│ Python Layer │ -│ ┌─────────────────────────────────────────────────────┐ │ -│ │ Python HybridEngine │ │ -│ │ - Orchestrates Python-defined components │ │ -│ │ - Custom ErrorModel, Machine, Decoder in Python │ │ -│ │ - Flexible experimentation │ │ -│ └──────────────────────┬──────────────────────────────┘ │ -│ │ │ -│ ┌──────────────────────┴──────────────────────────────┐ │ -│ │ PyO3 Bindings (pecos-rslib) │ │ -│ │ - SparseStab, StateVec exposed to Python │ │ -│ │ - WasmForeignObject for classical co-processors │ │ -│ │ - Engine builders for Rust-native pipelines │ │ -│ └──────────────────────┬──────────────────────────────┘ │ -└─────────────────────────┼───────────────────────────────────┘ - │ -┌─────────────────────────┼───────────────────────────────────┐ -│ Rust Layer │ -│ ┌──────────────────────┴──────────────────────────────┐ │ -│ │ Rust HybridEngine │ │ -│ │ - High-performance orchestration │ │ -│ │ - ByteMessage protocol │ │ -│ │ - Parallel Monte Carlo │ │ -│ └─────────────────────────────────────────────────────┘ │ -│ │ -│ ┌─────────────────────────────────────────────────────┐ │ -│ │ Rust Simulators │ │ -│ │ - SparseStab (stabilizer) │ │ -│ │ - StateVec (state vector) │ │ -│ │ - GPU backends │ │ -│ └─────────────────────────────────────────────────────┘ │ -└──────────────────────────────────────────────────────────────┘ -``` - -### Use Cases - -| Scenario | Approach | -|----------|----------| -| **Prototyping new error model** | Write in Python, use Rust simulator | -| **Custom QEC decoder** | Python decoder with Rust stabilizer sim | -| **Production simulation** | Full Rust pipeline via `sim()` API | -| **Research flexibility** | Mix Python and Rust components freely | -| **Classical co-processing** | WASM modules via WasmForeignObject | - -### Foreign Objects (Classical Co-Processors) - -For computationally intensive classical logic (decoders, lookup tables), PECOS supports WASM: - -```python -import tempfile -from pathlib import Path - -from pecos import WasmForeignObject - -# Create a minimal WASM module with a decode function -wat = """(module - (func $init) - (func $decode_syndrome (param i32) (result i32) (local.get 0)) - (memory (;0;) 1) - (export "init" (func $init)) - (export "decode_syndrome" (func $decode_syndrome)) - (export "memory" (memory 0)) -)""" -wat_path = Path(tempfile.mktemp(suffix=".wat")) -wat_path.write_text(wat) - -# Load and use -decoder_wasm = WasmForeignObject.from_file(str(wat_path)) -decoder_wasm.init() -result = decoder_wasm.exec("decode_syndrome", [42]) -``` - -This allows writing performance-critical classical code in Rust/C/C++ compiled to WASM, while keeping the orchestration in Python. - -## Summary - -The `pecos-engines` architecture provides: - -- **Modularity** - Swap simulators, noise models, or program formats independently -- **Composability** - Engines delegate to other engines via well-defined interfaces -- **Parallelism** - Automatic multi-threaded shot execution -- **Reproducibility** - Deterministic seed derivation -- **Flexibility** - Support for adaptive circuits via classical-quantum feedback -- **Extensibility** - FFI support and plugin architecture via ByteMessage protocol -- **Cross-language** - Python bindings and C ABI exports for external integration - -The key insights are: -1. The `EngineStage` pattern enables feedback loops between classical and quantum components, making mid-circuit measurements and classical control possible -2. The `ByteMessage` binary protocol provides a clean FFI boundary, enabling plugins, Python integration, and potential distributed simulation -3. The two-layer architecture (Python + Rust) allows users to prototype custom components in Python while leveraging Rust performance for simulation diff --git a/design/OPERATOR_TYPE_SYSTEM.md b/design/OPERATOR_TYPE_SYSTEM.md deleted file mode 100644 index aeab62541..000000000 --- a/design/OPERATOR_TYPE_SYSTEM.md +++ /dev/null @@ -1,275 +0,0 @@ -# Operator Type System Architecture - -This document describes the quantum operator type system in PECOS: the four algebraic levels (Pauli, Clifford, Unitary, Channel), their representations, the unified `Op` type with automatic promotion, and the Pauli collection hierarchy. - -## Design Principles - -1. **Tightest possible representation**: Each operator is represented at the most specific level that can express it. A Hadamard gate is Clifford, not "just a unitary". This enables level-specific optimizations (e.g., fast Pauli conjugation via tableaux). - -2. **Automatic promotion**: When combining operators from different levels, the result is promoted to the tightest level that can represent the combination. Pauli & Clifford -> Clifford. - -3. **Lazy expression trees**: At the Unitary and Channel levels, operators are stored as symbolic expression trees, not eagerly evaluated matrices. Composition (`*`) and tensor (`&`) build tree nodes. - -4. **Sparse by default**: Pauli strings store only non-identity entries. Clifford tableaux store only the images of generators that change. This handles large qubit counts efficiently. - -## Operator Levels - -``` -Level 0: Pauli PauliString Exact, finite group, symplectic algebra -Level 1: Clifford CliffordRep Heisenberg picture, O(n) Pauli conjugation -Level 2: Unitary UnitaryRep Lazy expression tree, any unitary -Level 3: Channel ChannelExpr Non-unitary: measurement, noise, reset -``` - -### Level 0: Pauli (`PauliString`) - -**File:** `crates/pecos-core/src/pauli/pauli_string.rs` - -```rust -pub struct PauliString { - phase: QuarterPhase, // {+1, -1, +i, -i} - paulis: Vec<(Pauli, QubitId)>, // sparse: only non-identity entries -} -``` - -The n-qubit Pauli group has 4^(n+1) elements (4 single-qubit Paulis, 4 phases). `PauliString` represents them sparsely -- a Pauli acting non-trivially on 3 out of 1000 qubits uses O(3) storage. - -**Key properties:** -- Exact arithmetic (no floating point) -- O(w) commutation check where w = total weight of both operators -- Multiplication produces another `PauliString` with computed phase -- The `PauliOperator` trait unifies `PauliString`, `PauliBitmap`, and `PauliSparse` - -**Constructor modules:** -- `pecos_core::pauli::constructors` -- `X(q)`, `Y(q)`, `Z(q)`, `Xs(qs)`, `Ys(qs)`, `Zs(qs)` -- `pecos_core::pauli::algebra` -- operator overloading: `&` (tensor), `*` (multiply), `-` (negate), `i *` (phase) - -**Alternative representations:** -- `PauliBitmap` -- u64 bitmasks for X and Z positions. Limited to 64 qubits, but bitwise operations are very fast. -- `PauliSparse` -- generic over the set type `T` for X/Z positions. Allows custom set implementations. - -### Level 1: Clifford (`CliffordRep`) - -**File:** `crates/pecos-core/src/clifford_rep.rs` - -```rust -pub struct CliffordRep { - num_qubits: usize, - x_images: Vec, // X_i -> PauliString - z_images: Vec, // Z_i -> PauliString -} -``` - -Represents a Clifford gate via the Heisenberg picture: how it conjugates each single-qubit Pauli generator. A Clifford on n qubits is fully specified by 2n generator images. - -**Why this representation:** -- Conjugating a weight-w Pauli string through a Clifford is O(w * n), not O(4^n) -- Composition of two Cliffords is O(n^2) -- Natural for stabilizer simulation and code analysis - -**Key methods:** -- `identity(n)`, `h(q)`, `cx(c, t)`, `s(q)`, etc. -- standard gate constructors -- `compose(&other)` -- C1 * C2 -- `apply(&pauli)` -- C * P * C^dag -- `inverse()` -- C^dag -- `from(PauliString)` -- every Pauli is a Clifford - -**Relation to `Clifford` enum:** The `Clifford` enum (`crates/pecos-core/src/clifford.rs`) lists the 24 single-qubit and 14 two-qubit Clifford primitives by name. `CliffordRep` is the algebraic representation used for computation. - -### Level 2: Unitary (`UnitaryRep`) - -**File:** `crates/pecos-core/src/unitary_rep.rs` - -```rust -pub enum UnitaryRep { - Pauli(PauliString), - Rotation { rotation_type: RotationType, angle: Angle64, qubits: SmallVec<[usize; 2]> }, - Gate { gate_type: GateType, qubits: SmallVec<[usize; 3]> }, - Tensor(Vec), - Compose(Vec), - Adjoint(Box), - Phase { phase: Angle64, inner: Box }, -} -``` - -A lazy expression tree that can represent any unitary, including non-Clifford gates (T, Rz(theta), etc.). Operations build tree nodes rather than evaluating eagerly. - -**Why an expression tree:** -- Composition and tensor product are O(1) (just wrap in a new node) -- The tree can be analyzed symbolically (e.g., `is_clifford()` checks) -- Different backends can evaluate the tree differently (matrix, stabilizer sim, etc.) - -**Constructor functions:** Defined in `crates/pecos-core/src/unitary_rep.rs`: -- Single-qubit: `X(q)`, `Y(q)`, `Z(q)`, `H(q)`, `SX(q)`, `SZ(q)`, `T(q)`, etc. -- Rotation: `RX(angle, q)`, `RY(angle, q)`, `RZ(angle, q)`, `RXX(angle, q0, q1)`, etc. -- Two-qubit: `CX(c, t)`, `CZ(q0, q1)`, `SWAP(q0, q1)`, `ISWAP(q0, q1)`, etc. -- Pluralized: `Hs([q0, q1, ...])`, `CXs([(c0,t0), (c1,t1)])` -- tensor multiple gates - -### Level 3: Channel (`ChannelExpr`) - -**File:** `crates/pecos-core/src/op.rs` - -```rust -pub enum ChannelExpr { - Prep { basis: Basis, qubit: usize }, - Measure { basis: Basis, qubit: usize }, - Unitary(UnitaryRep), - MixedUnitary(Vec<(f64, UnitaryRep)>), - AmplitudeDamping { gamma: f64, qubit: usize }, - PhaseDamping { lambda: f64, qubit: usize }, - Erasure { prob: f64, qubit: usize }, - Reset { qubit: usize }, - Leakage { rate: f64, qubit: usize }, - Tensor(Vec), - Compose(Vec), -} -``` - -Non-unitary quantum operations. These compose and tensor like unitaries but are not invertible (no `dg()`). - -**Notable variants:** -- `MixedUnitary` -- covers Pauli channels, depolarizing, dephasing, bit-flip via weighted sums of unitaries -- `AmplitudeDamping` / `PhaseDamping` -- explicit Kraus-operator channels for T1/T2 processes -- `Erasure` -- heralded error channel -- `Leakage` -- transition to non-computational states - -## The Unified `Op` Type - -**File:** `crates/pecos-core/src/op.rs` - -```rust -pub enum Op { - Pauli(PauliString), - Clifford(CliffordRep, UnitaryRep), - Unitary(UnitaryRep), - Channel(ChannelExpr), -} -``` - -`Op` wraps all four levels and provides automatic promotion via the `&` (tensor) and `*` (composition) operators. When combining two `Op` values, the result is at the maximum level of the operands. - -### Dual Representation at Clifford Level - -The `Clifford` variant stores both a `CliffordRep` (for efficient Pauli conjugation) and a `UnitaryRep` (for promotion to the Unitary level). This avoids information loss when mixing Clifford and non-Clifford operations. - -### Promotion Rules - -``` -Pauli & Pauli -> Pauli -Pauli & Clifford -> Clifford -Pauli & Unitary -> Unitary -Clifford & Unitary -> Unitary -anything & Channel -> Channel -``` - -Same rules apply for composition (`*`). - -### Extraction Methods - -`Op` provides both borrowing and consuming extractors: - -- `as_pauli()` / `into_pauli()` -- returns `None` for non-Pauli -- `as_clifford()` / `into_clifford()` -- Pauli promotes to Clifford; Unitary/Channel return `None` -- `as_unitary()` / `into_unitary()` -- Pauli and Clifford promote; Channel returns `None` -- `into_channel()` -- always succeeds (lower levels wrap in `ChannelExpr::Unitary`) - -### Constructor Functions - -`Op`-level constructors live in `crates/pecos-core/src/op.rs` and mirror the `UnitaryRep` constructors but return `Op` at the tightest level: - -- `X(q)`, `Z(q)` -- return `Op::Pauli` -- `H(q)`, `CX(c,t)`, `SZ(q)` -- return `Op::Clifford` -- `T(q)`, `RZ(angle, q)` -- return `Op::Unitary` -- `MZ(q)`, `PZ(q)`, `Depolarizing(p, q)` -- return `Op::Channel` - -**Important:** The constructors in `pecos_core::op` and `pecos_core::unitary_rep` have the same names (`X`, `H`, `T`, etc.) but return different types (`Op` vs `UnitaryRep`). Use `use pecos_core::op::*` for the unified `Op` algebra, or `use pecos_core::unitary_rep::*` for the `UnitaryRep`-only algebra. Similarly, `use pecos_core::pauli::constructors::*` gives `PauliString`-level constructors. - -## Pauli Collection Types - -**Crate:** `pecos-quantum` - -Four collection types with increasing algebraic constraints: - -``` -PauliSequence ──(validate commutativity)──> PauliGroup ──(validate real phases)──> PauliStabilizerGroup - -PauliSet (separate: unordered, deduplicated) -``` - -### PauliSequence - -**File:** `crates/pecos-quantum/src/pauli_sequence.rs` - -Ordered list of `PauliString`s with no constraints. Provides GF(2) symplectic analysis: - -- `rank()` -- number of linearly independent generators -- `row_reduce()` -- independent generator subset -- `contains(&pauli)` -- membership in GF(2) span (ignoring phase) -- `is_abelian()` -- check mutual commutativity -- `to_symplectic_matrix()` -- binary representation for linear algebra - -### PauliSet - -**File:** `crates/pecos-quantum/src/pauli_set.rs` - -Unordered set of unique `PauliString`s backed by `BTreeSet`. Phase-sensitive equality (+XZ and -XZ are distinct). Standard set operations (union, intersection, difference). - -### PauliGroup - -**File:** `crates/pecos-quantum/src/pauli_group.rs` - -Wraps `PauliSequence` with validated commutativity. Generators may have any `QuarterPhase`. When a generator has phase +i or -i, it has order 4 and the group contains -I (so it cannot stabilize any quantum state). - -### PauliStabilizerGroup - -**File:** `crates/pecos-quantum/src/stabilizer_group.rs` - -Wraps `PauliGroup` with the additional constraint that all generators have `Sign` phases (+1 or -1). This is the standard stabilizer group for QEC: every element squares to +I, and the group defines a valid code space. - -### Conversion Safety - -Widening conversions (dropping constraints) always succeed via `From`: -``` -PauliStabilizerGroup -> PauliGroup -> PauliSequence -``` - -Narrowing conversions (adding constraints) are fallible via `TryFrom`: -``` -PauliSequence -> PauliGroup (validates commutativity) -PauliGroup -> PauliStabilizerGroup (validates real phases) -PauliSequence -> PauliStabilizerGroup (validates both) -``` - -All types also have `from_generators_unchecked()` for internal use when constraints are known to hold. - -## File Organization - -``` -crates/pecos-core/src/ - pauli.rs -- Pauli enum, PauliOperator trait - pauli/ - pauli_string.rs -- PauliString (primary Pauli type) - pauli_bitmap.rs -- PauliBitmap (<=64 qubits, fast) - pauli_sparse.rs -- PauliSparse (generic) - constructors.rs -- X(), Y(), Z(), Xs(), Ys(), Zs() - algebra.rs -- operator overloading (&, *, -, i*) - clifford.rs -- Clifford enum (named gate primitives) - clifford_rep.rs -- CliffordRep (Heisenberg picture) - unitary_rep.rs -- UnitaryRep (expression tree) - op.rs -- Op (unified type), ChannelExpr - -crates/pecos-quantum/src/ - pauli_sequence.rs -- PauliSequence, F2Matrix - pauli_set.rs -- PauliSet - pauli_group.rs -- PauliGroup - stabilizer_group.rs -- PauliStabilizerGroup -``` - -## Relation to QEC Types - -The Pauli collection types feed into the QEC layer in `pecos-qec`: - -- `PauliStabilizerGroup` + `num_qubits` -> `StabilizerCode` (mathematical definition, on-demand analysis) -- `StabilizerCode` -> `StabilizerCodeSpec` (verified, with paired logicals, for fault tolerance) - -See [Stabilizer Code Architecture](STABILIZER_CODE_ARCHITECTURE.md) for details. diff --git a/design/QIS_ARCHITECTURE.md b/design/QIS_ARCHITECTURE.md deleted file mode 100644 index 7434b2f79..000000000 --- a/design/QIS_ARCHITECTURE.md +++ /dev/null @@ -1,646 +0,0 @@ -# QIS Architecture: Interface, Runtime, and Engine - - - -This document describes the architecture of the Quantum Instruction Set (QIS) system in PECOS, focusing on how quantum programs are compiled, executed, and simulated. - -## Overview - -The QIS architecture consists of three main components: - -1. **Interface Layer** - Compiles quantum programs and collects operations -2. **Runtime Layer** - Executes collected quantum operations -3. **Engine Layer** - Orchestrates interface and runtime - -``` -┌─────────────────────────────────────────────────────────────┐ -│ QisEngine │ -│ (pecos-qis) │ -│ │ -│ ┌─────────────────────┐ ┌──────────────────────┐ │ -│ │ QisInterface │ │ QisRuntime │ │ -│ │ (Interface Impl) │──────│ (Runtime Impl) │ │ -│ └─────────────────────┘ └──────────────────────┘ │ -│ │ │ │ -└───────────┼──────────────────────────────┼──────────────────┘ - │ │ - ▼ ▼ - Compile & Collect Execute Operations - Operations (Quantum Simulation) -``` - -## 1. Interface Architecture - -The **Interface Layer** is responsible for taking a quantum program (in various formats) and extracting the quantum operations from it. - -### Interface Trait - -Defined in `pecos-qis/src/qis_interface.rs`: - -```rust -pub trait QisInterface { - /// Load a quantum program - fn load_program(&mut self, program_bytes: &[u8], format: ProgramFormat) - -> Result<(), InterfaceError>; - - /// Collect operations from the loaded program - fn collect_operations(&mut self) -> Result; - - /// Execute with pre-set measurement results (for conditional operations) - fn execute_with_measurements(&mut self, measurements: HashMap) - -> Result; - - /// Get interface metadata - fn metadata(&self) -> HashMap; - - /// Interface name - fn name(&self) -> &'static str; - - /// Reset the interface state - fn reset(&mut self) -> Result<(), InterfaceError>; -} -``` - -### Helios Interface Implementation - -The **Helios Interface** (`QisHeliosInterface` in `pecos-qis`) is the primary interface implementation. It works by: - -1. **Compilation**: Linking quantum program bitcode with Selene's Helios library -2. **Dynamic Execution**: Loading and executing the compiled program in-process -3. **Operation Collection**: Capturing quantum operations via FFI interception - -#### Helios Interface Flow - -``` -User provides QIS bitcode/LLVM IR - ↓ -QisHeliosInterface.load_program() - ↓ - Compile with clang: - program.bc + libhelios.a → program.so - ↓ -QisHeliosInterface.collect_operations() - ↓ - Load libraries with RTLD_GLOBAL: - 1. libpecos_qis_ffi.so (provides __quantum__rt__*) - 2. libpecos_selene.so (provides selene_*) - 3. program.so (calls selene_*) - ↓ - Execute: qmain() or main() - ↓ - Collect operations from thread-local storage - ↓ - Return OperationCollector -``` - -### Symbol Resolution Chain - -When a quantum program executes, function calls are resolved through multiple layers: - -``` -program.so: qmain() - ↓ calls ___qalloc() - -libhelios.a (linked into program.so) - ↓ calls selene_qalloc() - -libpecos_selene.so (C shim, loaded with RTLD_GLOBAL) - │ File: pecos-qis/src/c/selene_shim.c - │ Purpose: Adapts Selene interface to PECOS FFI - ↓ calls __quantum__rt__qubit_allocate() - -libpecos_qis_ffi.so (Rust cdylib, loaded with RTLD_GLOBAL) - │ Crate: pecos-qis-ffi - │ Purpose: Provides QIS FFI functions - ↓ records operation - -OperationCollector (thread-local storage) - │ Records: AllocateQubit, H, CX, Measure, etc. - ↓ retrieved by - -QisHeliosInterface - │ Returns operations to QisEngine -``` - -### The Shim Layer (libpecos_selene.so) - -**Purpose**: Bridges Selene's C interface to PECOS Rust FFI - -**Location**: Built by `pecos-qis/build_selene.rs` from `src/c/selene_shim.c` - -**Example** (from `selene_shim.c`): -```c -selene_u64_result_t selene_qalloc(SeleneInstance *instance) { - (void)instance; // Unused - we use thread-local storage - int64_t qubit_id = __quantum__rt__qubit_allocate(); - return SUCCESS_VAL(selene_u64_result_t, (uint64_t)qubit_id); -} - -selene_void_result_t selene_rxy(SeleneInstance *instance, - uint64_t q, double theta, double phi) { - (void)instance; - __quantum__qis__r1xy__body(theta, phi, (int64_t)q); - return SUCCESS(selene_void_result_t); -} -``` - -**Why it exists**: Selene's Helios compiler expects functions with specific signatures (e.g., `selene_qalloc`). The shim provides these functions and forwards calls to our Rust FFI layer. - -### The FFI Layer (libpecos_qis_ffi.so) - -**Purpose**: Provides `__quantum__rt__*` and `__quantum__qis__*` symbols that record operations - -**Crate**: `pecos-qis-ffi` - -**Example** (from `pecos-qis-ffi/src/ffi.rs`): -```rust -#[unsafe(no_mangle)] -pub unsafe extern "C" fn __quantum__rt__qubit_allocate() -> i64 { - with_interface(|interface| { - let id = interface.allocate_qubit(); - interface.queue_operation(Operation::AllocateQubit { id }); - i64::try_from(id).expect("Qubit ID too large for i64") - }) -} - -#[unsafe(no_mangle)] -pub unsafe extern "C" fn __quantum__qis__h__body(qubit: i64) { - let qubit_id = i64_to_usize(qubit); - with_interface(|interface| { - interface.queue_operation(QuantumOp::H(qubit_id).into()); - }); -} -``` - -**Thread-local storage**: Operations are collected in thread-local `OperationCollector` that can be retrieved after execution. - -### Operation Collector - -The `OperationCollector` (in `pecos-qis-ffi`) stores: - -```rust -pub struct OperationCollector { - /// Allocated qubit IDs - pub allocated_qubits: Vec, - - /// Allocated result IDs - pub allocated_results: Vec, - - /// Sequence of quantum operations - pub operations: Vec, - - /// Measurement results (for conditional execution) - measurement_results: HashMap, -} -``` - -Operations include: -- `AllocateQubit`, `ReleaseQubit` -- `AllocateResult` -- Quantum gates: `H`, `X`, `Y`, `Z`, `S`, `T`, `CX`, `CY`, `CZ`, etc. -- Rotations: `RX`, `RY`, `RZ`, `RXY`, `RZZ`, etc. -- Measurements: `Measure`, `Reset` - -## 2. Runtime Architecture - -The **Runtime Layer** takes collected quantum operations and executes them using a quantum simulator. - -### Runtime Trait - -Defined in `pecos-qis/src/runtime.rs`: - -```rust -pub trait QisRuntime: Send + Sync + DynClone { - /// Execute quantum operations and return results - fn execute(&mut self, operations: &OperationCollector) - -> Result; - - /// Runtime name - fn name(&self) -> &'static str; - - /// Clone the runtime - fn clone_box(&self) -> Box; -} -``` - -### Selene Runtime Implementation - -The **Selene Runtime** wraps Selene's quantum simulator library (.so files). - -**Location**: `pecos-qis/src/selene_runtime.rs` - -#### Selene Runtime Types - -Selene provides multiple runtime variants (all are .so files): - -1. **Simple Runtime** (`libselene_simple_runtime.so`): - - State vector simulation - - Full quantum state tracking - - Function: `selene_simple_runtime()?` - -2. **Soft-Rz Runtime** (`libselene_soft_rz_runtime.so`): - - Optimized for Rz-heavy circuits - - Function: `selene_soft_rz_runtime()?` - -#### Runtime Wrapper Structure - -```rust -pub struct QisSeleneRuntime { - /// Path to the Selene runtime .so file - runtime_lib_path: PathBuf, - - /// Loaded runtime library - runtime_lib: Option, - - /// Runtime metadata - metadata: HashMap, -} -``` - -#### Runtime Execution Flow - -``` -QisEngine calls runtime.execute(operations) - ↓ -QisSeleneRuntime.execute() - ↓ - Load libselene_*_runtime.so - ↓ - Initialize Selene instance - ↓ - For each operation in OperationCollector: - - Translate to Selene API call - - Call runtime function via FFI - - Track quantum state in Selene - ↓ - Perform measurements (if any) - ↓ - Extract results from Selene - ↓ - Return RuntimeResult -``` - -#### Selene Runtime Functions - -Selene runtimes expose functions like: - -```c -// State management -SeleneInstance* selene_new_instance(void); -void selene_free_instance(SeleneInstance*); - -// Qubit operations -selene_u64_result_t selene_qalloc(SeleneInstance*); -selene_void_result_t selene_qfree(SeleneInstance*, uint64_t qubit); - -// Quantum gates -selene_void_result_t selene_rxy(SeleneInstance*, uint64_t q, double theta, double phi); -selene_void_result_t selene_rz(SeleneInstance*, uint64_t q, double theta); - -// Measurements -selene_bool_result_t selene_qubit_measure(SeleneInstance*, uint64_t qubit); -``` - -The `QisSeleneRuntime` wrapper calls these functions via `libloading` FFI. - -### Runtime Results - -The `RuntimeResult` contains: - -```rust -pub struct RuntimeResult { - /// Measurement outcomes (result_id → bool) - pub measurements: HashMap, - - /// Runtime-specific metadata - pub metadata: HashMap, -} -``` - -## 3. Engine Architecture (QisEngine) - -The **QisEngine** orchestrates the interface and runtime to provide a complete quantum program execution pipeline. - -**Location**: `pecos-qis/src/ccengine.rs` - -### QisEngine Structure - -```rust -pub struct QisEngine { - /// Interface implementation (e.g., QisHeliosInterface) - interface: Box, - - /// Runtime implementation (e.g., QisSeleneRuntime) - runtime: Box, - - /// Number of qubits in the current program - num_qubits: usize, - - /// Number of classical results - num_results: usize, -} -``` - -### Engine Builder Pattern - -Users construct a `QisEngine` using the builder pattern: - -```rust -use pecos_qis::{qis_engine, helios_interface_builder, selene_simple_runtime}; - -let engine = qis_engine() - .interface(helios_interface_builder()) // Set interface - .runtime(selene_simple_runtime()?) // Set runtime - .program(qis_program) // Load program - .build()?; // Build engine -``` - -**Builder location**: `pecos-qis/src/engine_builder.rs` - -### QisEngine Execution Flow - -#### 1. Initialization (build time) - -```rust -QisEngineBuilder::build() - ↓ -Interface: load_program(program_bytes) - ↓ (compiles program) -Interface: collect_operations() - ↓ (executes program, collects ops) -Store operations and metadata - ↓ -Return QisEngine -``` - -#### 2. Execution (run time) - -```rust -engine.run(options) - ↓ -For each shot: - ↓ - Runtime: execute(operations) - ↓ (simulates quantum circuit) - ↓ (performs measurements) - ↓ - Return RuntimeResult - ↓ -Aggregate results across shots - ↓ -Return SimulationResult -``` - -### Engine Responsibilities - -The `QisEngine` mediates between interface and runtime: - -1. **Initialization**: - - Uses interface to compile and collect operations - - Stores program metadata (num_qubits, num_results) - -2. **Execution**: - - Passes operations to runtime for each shot - - Handles multi-shot simulations - - Aggregates measurement results - -3. **Classical Control** (implements `ClassicalEngine` trait): - - Supports conditional operations based on measurements - - Manages measurement result storage - - Enables dynamic circuit execution - -## 4. Complete Example Flow - -Let's trace a complete example: executing a Bell state program. - -### Step 1: User Code - -```rust -use pecos_qis::{qis_engine, helios_interface_builder, selene_simple_runtime}; -use pecos_programs::Qis; -use pecos_engines::{ClassicalControlEngineBuilder, ClassicalEngine}; - -// Load Bell state program -let qis_program = Qis::from_file("bell.ll")?; - -// Build engine -let mut engine = qis_engine() - .interface(helios_interface_builder()) - .runtime(selene_simple_runtime()?) - .program(qis_program) - .build()?; - -// Run simulation -let result = engine.run(&sim_options)?; -``` - -### Step 2: Interface Processing (during build) - -``` -QisEngineBuilder::build() - ↓ -QisHeliosInterface::load_program(bell.ll) - ↓ - Compile: clang bell.ll + libhelios.a → bell.so - Store: temp file bell.so - ↓ -QisHeliosInterface::collect_operations() - ↓ - Load: libpecos_qis_ffi.so (RTLD_GLOBAL) - Load: libpecos_selene.so (RTLD_GLOBAL) - Load: bell.so - ↓ - Execute: qmain(0) - ↓ calls ___qalloc() [twice] - ↓ calls ___h() [once on qubit 0] - ↓ calls ___cx() [once: control=0, target=1] - ↓ - Operations recorded in thread-local: - - AllocateQubit { id: 0 } - - AllocateQubit { id: 1 } - - H(0) - - CX(0, 1) - ↓ - Return OperationCollector - ↓ -QisEngine stores: - - operations: [AllocateQubit(0), AllocateQubit(1), H(0), CX(0,1)] - - num_qubits: 2 -``` - -### Step 3: Runtime Execution (during run) - -``` -engine.run(sim_options) - ↓ -For shot in 0..num_shots: - ↓ - QisSeleneRuntime::execute(operations) - ↓ - Load: libselene_simple_runtime.so - Init: instance = selene_new_instance() - ↓ - Process operations: - AllocateQubit(0) → q0 = selene_qalloc(instance) - AllocateQubit(1) → q1 = selene_qalloc(instance) - H(0) → selene_rxy(instance, q0, π, 0) - CX(0, 1) → (implemented via Rxy+Rz+Rxy+Rz) - ↓ - Measurements (if any): - Measure(0, 0) → result = selene_qubit_measure(instance, q0) - Measure(1, 1) → result = selene_qubit_measure(instance, q1) - ↓ - Cleanup: selene_free_instance(instance) - ↓ - Return RuntimeResult { - measurements: {0: false, 1: false} (or {0: true, 1: true}) - } - ↓ -Aggregate across shots: - - Count: |00⟩ and |11⟩ states - - Expected: ~50% each for Bell state - ↓ -Return SimulationResult -``` - -## 5. Architecture Benefits - -This three-layer architecture provides: - -### Separation of Concerns - -- **Interface**: Handles program compilation and operation extraction -- **Runtime**: Handles quantum simulation -- **Engine**: Orchestrates and provides unified API - -### Flexibility - -- **Multiple Interfaces**: Can implement JIT, AOT, or other compilation strategies -- **Multiple Runtimes**: Can swap Selene for other simulators (QuEst, Qulacs, etc.) -- **Mix and Match**: Any interface can work with any runtime - -### Extensibility - -Adding a new interface: -```rust -pub struct MyCustomInterface { /* ... */ } - -impl QisInterface for MyCustomInterface { - fn load_program(&mut self, program: &[u8], format: ProgramFormat) - -> Result<(), InterfaceError> { - // Custom compilation logic - } - - fn collect_operations(&mut self) -> Result { - // Custom operation collection - } - // ... other methods -} -``` - -Adding a new runtime: -```rust -pub struct MyCustomRuntime { /* ... */ } - -impl QisRuntime for MyCustomRuntime { - fn execute(&mut self, operations: &OperationCollector) - -> Result { - // Custom simulation logic - } - // ... other methods -} -``` - -### Testability - -- Interface and runtime can be tested independently -- Mock implementations for unit testing -- Real implementations for integration testing - -## 6. Key Design Decisions - -### Why Dynamic Loading? - -The Helios interface uses dynamic loading (`dlopen`/`libloading`) because: - -1. **Symbol Resolution**: LLVM-compiled programs need `__quantum__rt__*` symbols available globally -2. **Flexibility**: Programs are compiled at runtime, not build time -3. **Interception**: We can intercept operations before they reach the simulator - -### Why Thread-Local Storage? - -Operation collection uses thread-local storage because: - -1. **Simplicity**: No need to pass context through C FFI calls -2. **Safety**: Each thread has independent operation collector -3. **Performance**: Thread-local access is fast - -### Why Separate Shim and FFI? - -We have both `libpecos_selene.so` (C shim) and `libpecos_qis_ffi.so` (Rust FFI) because: - -1. **Compatibility**: Helios expects specific C function signatures (`selene_*`) -2. **Type Safety**: Rust FFI provides safe operation collection -3. **Reusability**: FFI layer can be used by other interfaces, not just Helios - -## 7. Crate Organization - -``` -pecos-qis/ # Main QIS crate (with optional selene feature) -├── src/ -│ ├── lib.rs # Re-exports, prelude -│ ├── ccengine.rs # QisEngine -│ ├── engine_builder.rs # QisEngineBuilder -│ ├── qis_interface.rs # QisInterface trait -│ ├── runtime.rs # QisRuntime trait -│ ├── executor.rs # QisHeliosInterface (selene feature) -│ ├── selene_runtime.rs # SeleneRuntime (selene feature) -│ ├── selene_runtimes.rs # Runtime discovery (selene feature) -│ ├── shim.rs # Path to libpecos_selene.so (selene feature) -│ └── c/ -│ └── selene_shim.c # C shim implementation (selene feature) -├── build.rs # Main build script -├── build_selene.rs # Selene build logic (selene feature) -└── Cargo.toml -│ -pecos-qis-ffi/ # FFI layer (cdylib) -├── src/ -│ ├── lib.rs # OperationCollector, thread-local -│ ├── ffi.rs # __quantum__rt__* and __quantum__qis__* exports -│ └── operations.rs # Operation types -└── Cargo.toml # crate-type = ["rlib", "cdylib"] -``` - -## 8. Future Directions - -Potential extensions to this architecture: - -1. **Additional Interfaces**: - - JIT interface using LLVM Orc - - Ahead-of-time (AOT) compiled interface - - Direct QASM→operations interface - -2. **Additional Runtimes**: - - Native PECOS runtime (no Selene dependency) - - GPU-accelerated runtime (QuEst, Qulacs) - - Distributed runtime for large-scale simulation - -3. **Optimizations**: - - Operation fusion (combine multiple gates) - - Circuit optimization passes - - Lazy evaluation of operations - -4. **Features**: - - Noise models in runtime layer - - State vector inspection - - Intermediate measurements with classical control - -## Summary - -The QIS architecture provides a clean separation between: - -- **Interface** (compilation & operation collection) -- **Runtime** (quantum simulation) -- **Engine** (orchestration & API) - -This design enables flexibility, extensibility, and maintainability while supporting complex quantum program execution with features like conditional operations and multi-shot simulations. diff --git a/design/STABILIZER_CODE_ARCHITECTURE.md b/design/STABILIZER_CODE_ARCHITECTURE.md deleted file mode 100644 index 174a790d3..000000000 --- a/design/STABILIZER_CODE_ARCHITECTURE.md +++ /dev/null @@ -1,166 +0,0 @@ -# Stabilizer Code Architecture - -This document describes the architecture of the stabilizer code types in `pecos-qec` and how they relate to the Pauli algebra types in `pecos-core` and `pecos-quantum`. For the broader operator type system (Cliffords, unitaries, channels, `Op`), see [Operator Type System Architecture](OPERATOR_TYPE_SYSTEM.md). - -## Type Hierarchy - -The stabilizer code system is built in layers, from low-level Pauli algebra up to fault tolerance analysis: - -``` -pecos-core pecos-quantum pecos-qec -┌──────────────────┐ ┌─────────────────────┐ ┌──────────────────────────┐ -│ PauliString │ │ PauliStabilizerGroup │ │ StabilizerCode │ -│ Pauli (X,Y,Z,I) │────────▶│ PauliCollection │───▶│ (mathematical definition)│ -│ QuarterPhase │ │ F2Matrix │ ├──────────────────────────┤ -│ CliffordRep │ └─────────────────────┘ │ StabilizerCodeSpec │ -└──────────────────┘ │ (operational spec) │ - ├──────────────────────────┤ - │ StabilizerFlipChecker │ - │ PauliPropChecker │ - │ (fault tolerance) │ - └──────────────────────────┘ -``` - -## Two Stabilizer Code Types - -There are two distinct stabilizer code types in `pecos-qec`, serving different roles: - -### `StabilizerCode` -- The Mathematical Definition - -**File:** `crates/pecos-qec/src/stabilizer_code.rs` - -A lightweight type that wraps a `PauliStabilizerGroup` together with an explicit `num_qubits`. This is the mathematical definition of a stabilizer code: a subgroup of the Pauli group that defines a code space. - -```rust -pub struct StabilizerCode { - group: PauliStabilizerGroup, - num_qubits: usize, -} -``` - -**Purpose:** On-demand QEC analysis. Given just the stabilizer generators, it can compute: - -- `num_logical_qubits()` -- `n - rank` via GF(2) linear algebra -- `logical_operators()` -- centralizer computation over GF(2) -- `distance()` -- coset enumeration (exponential, small codes only) -- `syndrome(error)` -- commutation check against each generator -- `apply_clifford(C)` -- conjugate all generators by a Clifford - -**Key design decisions:** - -- **Explicit `num_qubits`**: Stabilizer generators may not touch all physical qubits. For example, `ZZ` on a 4-qubit system defines a `[[4, 3]]` code, not a `[[2, 1]]` code. The explicit qubit count determines the code parameters. -- **Computed on demand**: Nothing is precomputed or cached. Each call to `logical_operators()` or `distance()` redoes the computation. This keeps the type simple and stateless. -- **Standard constructors**: `repetition(n)`, `steane()`, `five_qubit()`, `shor()`, `four_two_two()`, `toric(l)` provide well-known codes. - -### `StabilizerCodeSpec` -- The Operational Specification - -**File:** `crates/pecos-qec/src/stabilizer_code_spec.rs` - -A heavier type that stores explicit stabilizers, destabilizers, paired logical operators, and optional distance. Used by the fault tolerance analysis stack. - -```rust -pub struct StabilizerCodeSpec { - num_qubits: usize, - stabilizers: Vec, - destabilizers: Vec, - logical_zs: Vec, - logical_xs: Vec, - distance: Option, -} -``` - -**Purpose:** Verification and fault tolerance analysis. Provides: - -- **Verification methods**: `verify()` checks all commutation relations (stabilizers commute, logicals commute with stabilizers, X/Z pairs anticommute, cross-logical commutation). -- **Column-indexed lookups**: `build_stabilizer_index()` creates an O(weight) anticommutation index for efficient syndrome computation. -- **Builder pattern**: Fluent API for constructing codes with explicit logical operators. -- **Logical pairing**: Stores matched (X_i, Z_i) pairs, unlike `StabilizerCode` which returns an unpaired basis. - -**Key design decisions:** - -- **Paired logicals**: Fault tolerance analysis needs to know which logical X goes with which logical Z. `StabilizerCodeSpec` enforces this pairing. -- **Destabilizers**: Stored explicitly for use in stabilizer simulation and error correction. -- **Verification-first**: The `verify()` method checks all algebraic constraints before the code is used for analysis. This catches bugs in code definitions early. - -### Why Two Types? - -They serve different roles: - -| Feature | `StabilizerCode` | `StabilizerCodeSpec` | -|---|---|---| -| Input | Generators only | Generators + logicals + destabilizers | -| Computation | On-demand (centralizer, coset) | Pre-stored, verified | -| Logical operators | Unpaired basis | Paired (X_i, Z_i) | -| Verification | None (algebraic correctness assumed) | Full commutation verification | -| Column indexing | No | Yes (O(weight) lookups) | -| Used by | Exploratory analysis, code discovery | Fault tolerance stack | - -### Conversion - -`StabilizerCode` can be converted to `StabilizerCodeSpec` via: - -```rust -// Direct conversion (discovers logicals via stabilizer simulation) -let spec = StabilizerCodeSpec::from_stabilizer_code(&code)?; - -// Via builder (for adding manual logicals) -let spec = StabilizerCodeSpecBuilder::from_stabilizer_code(&code) - .logical_z(Zs([0, 1, 2])) - .logical_x(Xs([0])) - .build() - .unwrap(); -``` - -The `from_stabilizer_code` method uses `discover_logicals()` which runs a stabilizer simulation to find properly paired (X_i, Z_i) logical operators and their corresponding destabilizers. - -## Supporting Types - -### `PauliStabilizerGroup` (pecos-quantum) - -A purely algebraic type: a collection of commuting Pauli strings with real phases (+1 or -1). No QEC interpretation. Provides: - -- `rank()` -- GF(2) rank of the generator matrix -- `row_reduce()` -- reduced row echelon form over GF(2) -- `centralizer_in(n)` -- centralizer of the group in the n-qubit Pauli group -- `to_symplectic_matrix()` -- binary symplectic representation -- `apply_clifford(C)` -- conjugate all elements - -### `F2Matrix` (pecos-quantum) - -Matrix over GF(2) for symplectic linear algebra. Used internally for rank computation, row reduction, and centralizer calculation. - -### `CliffordRep` (pecos-core) - -Sparse representation of a Clifford unitary as conjugation rules on single-qubit Paulis. Used by `StabilizerCode::apply_clifford()` to transform code generators. - -## Fault Tolerance Integration - -The fault tolerance module in `pecos-qec` consumes `StabilizerCodeSpec`: - -- **`StabilizerFlipChecker`**: Code-level analysis. Takes a `StabilizerCodeSpec` and checks whether faults of a given weight can cause undetectable logical errors. Works without a circuit. - -- **`PauliPropChecker`**: Circuit-level analysis. Takes a syndrome extraction circuit, then propagates Pauli faults through it to verify fault tolerance of a specific implementation. - -- **`GadgetChecker`**: Gadget-level analysis. Extends `PauliPropChecker` with explicit input/output qubit tracking for analyzing gadgets in composed QEC protocols. Enforces the s + r <= t constraint (input fault weight + internal fault weight). - -`StabilizerFlipChecker` uses the column-indexed anticommutation structure provided by `StabilizerCodeSpec` for efficient syndrome computation. - -## Module Organization - -``` -crates/pecos-qec/src/ - lib.rs -- crate root, re-exports - stabilizer_code.rs -- StabilizerCode (mathematical definition) - stabilizer_code_spec.rs -- StabilizerCodeSpec (operational spec) - logical_discovery.rs -- discover_logicals() via stabilizer simulation - distance.rs -- distance calculation algorithms - geometry.rs -- physical layout types - surface.rs -- surface code geometry - fault_tolerance/ -- fault tolerance analysis - mod.rs - stabilizer_flip_checker.rs - pauli_prop_checker.rs - gadget_checker.rs -- gadget-level fault tolerance (input/output tracking) - dem_builder.rs -- detector error model construction - ... -``` diff --git a/design/circuit-representations.md b/design/circuit-representations.md deleted file mode 100644 index a9187ae2b..000000000 --- a/design/circuit-representations.md +++ /dev/null @@ -1,346 +0,0 @@ -# Circuit Representations (Internal) - - - -This document covers the internal circuit representations used in PECOS's Rust core. For user-facing documentation on building and manipulating circuits, see the [User Guide: Circuit Representation](../user-guide/circuit-representation.md). - -## Overview - -PECOS uses four internal circuit representations, each optimized for different stages of the compilation and simulation pipeline: - -| Representation | Level | Storage | Mutable | Primary Use | -|----------------|-------|---------|---------|-------------| -| `Hugr` | High-level IR | Hierarchical graph | External | Compilation input, interop | -| `SimpleHugr` | Validated wrapper | Pre-processed cache | No | Fast iteration over simple circuits | -| `DagCircuit` | DAG | Nodes + edges | Yes | Optimization, analysis, construction | -| `TickCircuit` | Time-sliced | Vec of ticks | Yes | Hardware scheduling, QEC | - -## Hugr (Higher-order Unified Graph Representation) - -HUGR is a standard intermediate representation developed alongside tket2 and guppylang. It represents the full semantics of hybrid quantum-classical programs. - -### Capabilities - -- **Control flow**: Conditionals, CFG nodes, function calls -- **Loops**: TailLoop nodes for iteration -- **Classical computation**: Arithmetic, logic, data structures -- **Hierarchical structure**: Nested regions, modules -- **Type system**: Linear types for qubits, classical types - -### When HUGR is Used - -1. **Input from Guppy**: Guppy compiles to HUGR bytecode -2. **Interoperability**: Exchange format with tket2 and other tools -3. **Dynamic programs**: Programs with runtime-dependent control flow - -### Limitations for Simulation - -HUGR's generality makes it complex to simulate directly. For simple quantum circuits (no control flow), we convert to `DagCircuit` or wrap in `SimpleHugr` for efficient access. - -### Key Types - -```rust -// From the `hugr` crate (external dependency) -use hugr::{Hugr, HugrView, Node, Wire}; - -// PECOS conversion functions -use pecos_quantum::hugr_convert::{ - hugr_to_dag_circuit, - dag_circuit_to_hugr, - SimpleHugr, -}; -``` - -## SimpleHugr - -A validated wrapper around HUGR that guarantees the circuit is "simple" (no control flow) and provides efficient access through the `Circuit` trait. - -### Validation - -Construction fails if the HUGR contains: -- `Conditional` nodes -- `TailLoop` nodes -- `CFG` nodes -- `Case` nodes - -```rust -use pecos_quantum::hugr_convert::{SimpleHugr, NotSimpleError}; - -match SimpleHugr::try_new(hugr) { - Ok(simple) => { - // Safe to iterate efficiently - for gate in simple.iter_gates_topo() { - // ... - } - } - Err(NotSimpleError::ContainsConditional) => { - // Fall back to full HUGR execution - } - // ... -} -``` - -### Pre-computed Structure - -On construction, `SimpleHugr` caches: -- Topological order of gates -- Predecessor/successor relationships -- Qubit-to-gate mappings -- Root and leaf gates -- Circuit depth - -This avoids repeated graph traversals during simulation. - -### When to Use - -- When you receive a HUGR but expect it to be a simple circuit -- When you need `Circuit` trait compatibility without conversion overhead -- For read-only circuit analysis - -## DagCircuit - -The primary internal representation for circuit manipulation. Gates are nodes, qubit wires are labeled edges. - -### Design - -Follows the design of Qiskit's `DAGCircuit` and HUGR's dataflow regions: -- Edges represent qubit wires (not just dependencies) -- Each edge is labeled with the `QubitId` it carries -- Two-qubit gates have two incoming and two outgoing edges - -### Capabilities - -- **Mutable**: Add/remove gates, rewire connections -- **Rich queries**: Predecessors, successors, layers, qubit timelines -- **Attributes**: Metadata on circuit, gates, and wires -- **Builder API**: Fluent methods with auto-wiring - -### Implementation Notes - -```rust -pub struct DagCircuit { - /// The underlying DAG structure (from pecos-num) - dag: DAG, - /// Gates stored by node index - gates: Vec>, - /// Qubit labels for each edge - edge_qubits: BTreeMap, - /// Tracks the most recent gate on each qubit (for builder mode) - qubit_heads: BTreeMap, - /// Last added node (for .meta() calls) - last_node: Option, -} -``` - -The `qubit_heads` map enables the builder API to automatically wire consecutive gates on the same qubit. - -## TickCircuit - -A time-sliced representation where each "tick" contains gates that execute in parallel. - -### Design - -```rust -pub struct TickCircuit { - ticks: Vec, - next_tick: usize, - circuit_attrs: BTreeMap, -} - -pub struct Tick { - gates: Vec, - gate_attrs: BTreeMap>, - attrs: BTreeMap, // Tick-level metadata -} -``` - -### Qubit Conflict Detection - -Each tick enforces that no qubit is used by multiple gates: - -```rust -impl Tick { - pub fn try_add_gate(&mut self, gate: Gate) -> Result { - let conflicts = self.find_conflicts(&gate.qubits); - if !conflicts.is_empty() { - return Err(QubitConflictError { conflicting_qubits: conflicts, tick_idx: None }); - } - Ok(self.add_gate(gate)) - } -} -``` - -### Use Cases - -- **QEC syndrome extraction**: Each tick is a round -- **Hardware scheduling**: Maps to clocked execution -- **Timing metadata**: Attach round numbers, durations to ticks - -## The Circuit Trait - -Both `DagCircuit` and `SimpleHugr` implement the `Circuit` trait, enabling generic algorithms: - -```rust -pub trait Circuit { - // Basic properties - fn gate_count(&self) -> usize; - fn wire_count(&self) -> usize; - fn qubits(&self) -> Vec; - fn depth(&self) -> usize; - - // Gate access - fn gate(&self, index: GateHandle) -> Option<&Gate>; - fn iter_gates(&self) -> Box> + '_>; - fn iter_gates_topo(&self) -> Box> + '_>; - - // Graph structure - fn predecessors(&self, gate: GateHandle) -> Vec; - fn successors(&self, gate: GateHandle) -> Vec; - fn roots(&self) -> Vec; - fn leaves(&self) -> Vec; - - // Qubit queries - fn gates_on_qubit(&self, qubit: QubitId) -> Vec; - fn qubit_timeline(&self, qubit: QubitId) -> Vec; - - // Attributes - fn circuit_attrs(&self) -> &BTreeMap; - fn gate_attrs(&self, gate: GateHandle) -> Option<&BTreeMap>; -} -``` - -### CircuitMut Trait - -For mutable operations (only `DagCircuit` implements this): - -```rust -pub trait CircuitMut: Circuit { - fn add_gate(&mut self, gate: Gate) -> GateHandle; - fn remove_gate(&mut self, gate: GateHandle) -> Option; - fn set_circuit_attr(&mut self, key: impl Into, value: Attribute); - fn set_gate_attr(&mut self, gate: GateHandle, key: impl Into, value: Attribute) -> bool; -} -``` - -## Conversions - -### Conversion Graph - -``` - hugr_to_dag_circuit() - Hugr ─────────────────────> DagCircuit <────> TickCircuit - │ ^ │ - │ try_new() │ │ - v │ │ - SimpleHugr ────────────────────────+ │ - (implements Circuit) │ - │ - From/Into traits ──────────+ -``` - -### HUGR <-> DagCircuit - -```rust -// HUGR to DagCircuit -let dag = hugr_to_dag_circuit(&hugr)?; - -// DagCircuit to HUGR -let hugr = dag_circuit_to_hugr(&dag)?; -``` - -**HUGR -> DagCircuit algorithm:** -1. Extract quantum operations from tket.quantum extension -2. Process in topological order (QAlloc nodes first) -3. Track qubit identity through wire connections -4. Build edges based on qubit flow - -**DagCircuit -> HUGR algorithm:** -1. Create DFG builder with qubit type signature -2. Process gates in topological order -3. Track wire mappings for each qubit -4. Handle rotation gates specially (add ConstRotation inputs) - -### DagCircuit <-> TickCircuit - -```rust -// DagCircuit to TickCircuit (layers become ticks) -let tick_circuit = TickCircuit::from(&dag_circuit); - -// TickCircuit to DagCircuit (auto-wire by qubit) -let dag_circuit = DagCircuit::from(&tick_circuit); -``` - -**DagCircuit -> TickCircuit:** -- Each layer of parallel gates becomes a tick -- Gate attributes are preserved -- Tick-level attributes stored with `tick[N].key` prefix in DAG - -**TickCircuit -> DagCircuit:** -- Gates added in tick order -- Consecutive gates on same qubit are wired -- Tick attributes restored from prefixed keys - -### HUGR -> SimpleHugr - -```rust -let simple = SimpleHugr::try_new(hugr)?; - -// Access underlying HUGR if needed -let hugr_ref = simple.as_hugr(); -let hugr_owned = simple.into_hugr(); -``` - -## Performance Considerations - -### When to Convert - -| Scenario | Recommendation | -|----------|----------------| -| Single pass over gates | Use `SimpleHugr` (avoids conversion) | -| Multiple optimization passes | Convert to `DagCircuit` once | -| Need to modify circuit | Must use `DagCircuit` | -| Hardware scheduling | Convert to `TickCircuit` | -| Interop with tket | Keep as `Hugr` | - -### Conversion Costs - -- **HUGR -> DagCircuit**: O(n) where n = nodes, requires graph traversal -- **DagCircuit -> TickCircuit**: O(n + d) where d = depth (layer computation) -- **HUGR -> SimpleHugr**: O(n) validation + structure caching - -### Memory - -- `DagCircuit`: ~3 allocations per gate (node, gate storage, edge labels) -- `TickCircuit`: 1 Vec per tick + 1 Vec per gate -- `SimpleHugr`: Original HUGR + cached vectors - -## Adding New Circuit Types - -To add a new circuit representation: - -1. **Implement `Circuit` trait** for read-only access -2. **Optionally implement `CircuitMut`** if mutable -3. **Add conversion functions** to/from `DagCircuit` -4. **Consider validation** (like `SimpleHugr::try_new`) - -Example skeleton: - -```rust -pub struct MyCircuit { - // Internal storage -} - -impl Circuit for MyCircuit { - fn gate_count(&self) -> usize { /* ... */ } - fn wire_count(&self) -> usize { /* ... */ } - // ... implement all required methods -} - -impl From<&DagCircuit> for MyCircuit { - fn from(dag: &DagCircuit) -> Self { /* ... */ } -} - -impl From<&MyCircuit> for DagCircuit { - fn from(my: &MyCircuit) -> Self { /* ... */ } -} -``` diff --git a/design/pecos-cuquantum-plan.md b/design/pecos-cuquantum-plan.md deleted file mode 100644 index fa6ed9606..000000000 --- a/design/pecos-cuquantum-plan.md +++ /dev/null @@ -1,225 +0,0 @@ -# Plan: pecos-cuquantum Crate - -## Overview - -Create Rust bindings for NVIDIA's [cuQuantum SDK](https://developer.nvidia.com/cuquantum-sdk) to provide CUDA-accelerated quantum simulation in PECOS. - -## cuQuantum SDK Components - -The SDK includes five libraries (as of v25.x): - -| Library | Purpose | PECOS Relevance | -|---------|---------|-----------------| -| **cuStateVec** | State vector simulation | Alternative to `GpuStateVec` (wgpu) | -| **cuStabilizer** | Stabilizer/Clifford simulation | Alternative to `GpuStab`/`GpuStabMulti` | -| **cuTensorNet** | Tensor network contraction | Advanced simulation methods | -| **cuDensityMat** | Density matrix simulation | Noise modeling | -| **cuPauliProp** | Pauli propagation | Efficient Pauli tracking | - -**Priority**: cuStateVec and cuStabilizer are most relevant initially. - -## Architecture - -``` -pecos-cuquantum-sys/ # Raw FFI bindings (generated by bindgen) - src/ - lib.rs # bindgen output + manual additions - build.rs # Find/download cuQuantum, run bindgen - -pecos-cuquantum/ # Safe Rust wrapper - src/ - lib.rs - statevec.rs # cuStateVec wrapper - stabilizer.rs # cuStabilizer wrapper - error.rs # Error handling - build.rs # Link configuration -``` - -## Dependency Management - -### Option 1: System Installation (Preferred for users with CUDA) -- Check `CUQUANTUM_ROOT` environment variable -- Check standard paths: `/usr/local/cuquantum`, `/opt/nvidia/cuquantum` -- Check if installed via apt/conda - -### Option 2: Auto-download to ~/.pecos/cuquantum/ -- Download tarball from NVIDIA (requires accepting license) -- Extract to `~/.pecos/cuquantum//` -- Cache for reuse across builds - -### Detection Order (similar to pecos-build cuda.rs) -```rust -pub fn find_cuquantum() -> Option { - // 1. ~/.pecos/cuquantum/ - // 2. CUQUANTUM_ROOT env var - // 3. Standard system paths - // 4. Derive from ldconfig/pkg-config -} -``` - -## C API Bindings - -### Header Files -```c -#include // State vector API -#include // Stabilizer API (if available) -#include // Complex number types -``` - -### Key cuStateVec Functions -```c -// Handle management -custatevecCreate(custatevecHandle_t* handle); -custatevecDestroy(custatevecHandle_t handle); - -// Gate application -custatevecApplyMatrix(handle, sv, dataType, nQubits, matrix, ...); -custatevecApplyMatrixGetWorkspaceSize(...); - -// Measurement -custatevecMeasure(handle, sv, dataType, nQubits, ...); -custatevecSample(handle, sv, dataType, nQubits, ...); - -// Expectation -custatevecComputeExpectation(...); -``` - -### bindgen Configuration -```rust -// build.rs -let bindings = bindgen::Builder::default() - .header("wrapper.h") - .clang_arg(format!("-I{}/include", cuquantum_path)) - .clang_arg(format!("-I{}/include", cuda_path)) - .allowlist_function("custatevec.*") - .allowlist_type("custatevec.*") - .allowlist_var("CUSTATEVEC_.*") - .generate() - .expect("Failed to generate bindings"); -``` - -## Safe Rust API Design - -### CuStateVec -```rust -pub struct CuStateVec { - handle: custatevecHandle_t, - state: DeviceBuffer, - num_qubits: usize, -} - -impl CuStateVec { - pub fn new(num_qubits: usize) -> Result; - - // Gate application - pub fn apply_matrix(&mut self, targets: &[usize], matrix: &[Complex64]) -> Result<(), _>; - pub fn h(&mut self, qubit: usize) -> Result<(), _>; - pub fn cx(&mut self, control: usize, target: usize) -> Result<(), _>; - // ... other gates - - // Measurement - pub fn measure(&mut self, qubit: usize) -> Result; - pub fn sample(&mut self, num_samples: usize) -> Result, _>; -} - -// Implement PECOS traits -impl CliffordGateable for CuStateVec { ... } -impl Measurable for CuStateVec { ... } -``` - -### CuStabilizer (if SDK includes it) -```rust -pub struct CuStabilizer { - // Wrapper for cuStabilizer -} - -impl CliffordGateable for CuStabilizer { ... } -``` - -## Build System Integration - -### pecos.toml Addition -```toml -[dependencies.cuquantum] -version = "25.11.0" -url = "https://developer.download.nvidia.com/..." # If redistributable -sha256 = "..." -description = "NVIDIA cuQuantum SDK" -requires_cuda = true - -[crates.pecos-cuquantum] -dependencies = ["cuquantum"] -requires_cuda = true -optional = true # Don't fail if CUDA unavailable -``` - -### Feature Flags -```toml -# pecos-cuquantum/Cargo.toml -[features] -default = [] -cuda-12 = [] # Link against CUDA 12 -cuda-11 = [] # Link against CUDA 11 -download = [] # Auto-download cuQuantum if not found -``` - -## Implementation Steps - -### Phase 1: Foundation -1. Add cuQuantum detection to `pecos-build/src/cuquantum.rs` -2. Create `pecos-cuquantum-sys` crate with bindgen -3. Verify bindings compile and link - -### Phase 2: Safe Wrapper -4. Create `pecos-cuquantum` crate -5. Implement `CuStateVec` wrapper -6. Add basic gates (H, X, Y, Z, S, T, CX, CZ) -7. Add measurement and sampling - -### Phase 3: PECOS Integration -8. Implement `CliffordGateable` trait -9. Add benchmarks comparing to `GpuStateVec` -10. Add cuStabilizer wrapper if available - -### Phase 4: Polish -11. Error handling improvements -12. Documentation -13. CI testing (requires CUDA runner) - -## Considerations - -### License -- cuQuantum SDK has its own license (not open source) -- Need to handle redistribution carefully -- May need to download at build time rather than bundle - -### CUDA Version Compatibility -- cuQuantum requires specific CUDA versions -- Need to match CUDA toolkit version -- pecos-build already handles CUDA detection - -### Multi-GPU Support -- cuStateVec supports multi-GPU via cuStateVecEx -- Consider exposing this for large simulations - -### Comparison with wgpu Backend -| Aspect | wgpu (GpuStateVec) | cuQuantum | -|--------|-------------------|-----------| -| Portability | Cross-platform | NVIDIA only | -| Performance | Good | Optimized for NVIDIA | -| Dependencies | Minimal | CUDA + cuQuantum | -| Maintenance | In-house | NVIDIA maintained | - -## Open Questions - -1. **cuStabilizer availability**: Is cuStabilizer a separate library or part of cuStateVec? -2. **License for auto-download**: Can we auto-download or must users accept license manually? -3. **Minimum CUDA version**: What CUDA versions should we support? -4. **Testing infrastructure**: Do we have CI runners with NVIDIA GPUs? - -## References - -- [cuQuantum Documentation](https://docs.nvidia.com/cuda/cuquantum/latest/index.html) -- [cuStateVec API Reference](https://docs.nvidia.com/cuda/cuquantum/latest/custatevec/index.html) -- [cuQuantum GitHub Samples](https://github.com/NVIDIA/cuQuantum/tree/main/samples) -- [Getting Started Guide](https://docs.nvidia.com/cuda/cuquantum/latest/getting-started/index.html) diff --git a/design/proposals/byte_message_api_cleanup.md b/design/proposals/byte_message_api_cleanup.md deleted file mode 100644 index a1c69daaf..000000000 --- a/design/proposals/byte_message_api_cleanup.md +++ /dev/null @@ -1,36 +0,0 @@ -# ByteMessageBuilder API Cleanup - -## Changes Made - -### Rust API - -Two-qubit gates now take `&[(usize, usize)]` (slice of pairs) instead of separate slices: - -```rust -// Before: -builder.cx(&[0], &[1]); -builder.rzz(theta, &[0], &[1]); - -// After: -builder.cx(&[(0, 1)]); -builder.rzz(theta, &[(0, 1)]); - -// Batch: -builder.cx(&[(0, 1), (2, 3)]); -``` - -Affected methods: `cx`, `cy`, `cz`, `szz`, `szzdg`, `rzz` - -### Rename: `mz` -> `mz` - -The method name now matches the gate name (MZ). - -### Python API - -Single-qubit gates take lists: `h([0, 1, 2])` -Two-qubit gates take lists of tuples: `cx([(0, 1), (2, 3)])` -Measurements renamed: `mz([0, 1])` - -## Status - -Done. Both Rust and Python APIs updated. diff --git a/design/proposals/slr-ast.md b/design/proposals/slr-ast.md deleted file mode 100644 index 522168a4c..000000000 --- a/design/proposals/slr-ast.md +++ /dev/null @@ -1,973 +0,0 @@ -# SLR Abstract Syntax Tree (AST) Proposal - - - -## Status - -**Draft** - Ready for review - ---- - -## Motivation - -### Current State - -SLR currently uses Python classes directly as both the syntax and the runtime representation: - -```python -prog = Main( - q := QReg("q", 2), - c := CReg("c", 2), - qb.H(q[0]), - qb.CX(q[0], q[1]), - qb.Measure(q) > c, -) -``` - -This approach has drawbacks: - -1. **Mixed concerns**: Representation classes also contain execution logic -2. **Difficult analysis**: No clean separation for static analysis passes -3. **Inconsistent structure**: Different node types have different interfaces -4. **Hard to transform**: Modifying programs requires understanding implementation details -5. **Code generation complexity**: Generators work directly with heterogeneous objects - -### Benefits of a Formal AST - -1. **Clean separation**: Syntax representation separate from semantics -2. **Uniform interface**: All nodes share a common base with predictable structure -3. **Easy traversal**: Visitor pattern for analysis and transformation -4. **Better tooling**: Linting, formatting, refactoring tools -5. **Simpler code gen**: One AST → multiple targets (QASM, Guppy, HUGR, etc.) -6. **Integration with QAlloc**: Clean representation of allocator hierarchy and slot states - ---- - -## Design Principles - -### 1. Immutable Data Structures - -AST nodes should be immutable dataclasses. This enables: -- Safe sharing and caching -- Easy equality comparison -- Predictable behavior in analysis passes - -### 2. Type Safety - -Use Python's type system with generics and protocols: -- All nodes have precise types -- Analysis results are strongly typed -- IDE support for navigation and refactoring - -### 3. Location Tracking - -Every node can optionally track source location for error reporting: -```python -@dataclass(frozen=True) -class SourceLocation: - line: int - column: int - file: str | None = None -``` - -### 4. Visitor Pattern - -Support the visitor pattern for analysis and transformation: -```python -class ASTVisitor(Protocol[T]): - def visit_program(self, node: Program) -> T: ... - def visit_gate(self, node: GateOp) -> T: ... - - # etc. -``` - -### 5. Bidirectional Conversion - -The AST should support: -- Building from current SLR objects (`from_slr()`) -- Converting back for execution (`to_slr()`) -- Direct construction for new code - ---- - -## AST Node Hierarchy - -### Base Types - -```python -from __future__ import annotations -from abc import ABC, abstractmethod -from dataclasses import dataclass, field -from enum import Enum, auto -from typing import TypeVar, Generic, Protocol, Sequence - - -@dataclass(frozen=True) -class SourceLocation: - """Source location for error reporting.""" - - line: int - column: int - file: str | None = None - - -@dataclass(frozen=True) -class ASTNode(ABC): - """Base class for all AST nodes.""" - - location: SourceLocation | None = field(default=None, compare=False) - - @abstractmethod - def accept(self, visitor: ASTVisitor[T]) -> T: - """Accept a visitor for traversal.""" - ... - - def children(self) -> Sequence[ASTNode]: - """Return child nodes for traversal.""" - return () -``` - -### Program Structure - -```python -@dataclass(frozen=True) -class Program(ASTNode): - """Root node representing an SLR program.""" - - name: str - allocator: AllocatorDecl | None # Base allocator (required in strict mode) - declarations: tuple[Declaration, ...] - body: tuple[Statement, ...] - returns: tuple[TypeExpr, ...] = () - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_program(self) - - def children(self) -> Sequence[ASTNode]: - nodes = [] - if self.allocator: - nodes.append(self.allocator) - nodes.extend(self.declarations) - nodes.extend(self.body) - return nodes -``` - -### Declarations - -```python -class Declaration(ASTNode, ABC): - """Base for all declarations.""" - - pass - - -@dataclass(frozen=True) -class AllocatorDecl(Declaration): - """Qubit allocator declaration.""" - - name: str - capacity: int - parent: str | None = None # Name of parent allocator - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_allocator_decl(self) - - -@dataclass(frozen=True) -class RegisterDecl(Declaration): - """Classical register declaration.""" - - name: str - size: int - is_result: bool = True - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_register_decl(self) -``` - -### Statements - -```python -class Statement(ASTNode, ABC): - """Base for all statements.""" - - pass - - -@dataclass(frozen=True) -class GateOp(Statement): - """Quantum gate application.""" - - gate: GateKind - targets: tuple[SlotRef, ...] - params: tuple[Expression, ...] = () - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_gate(self) - - def children(self) -> Sequence[ASTNode]: - return (*self.targets, *self.params) - - -@dataclass(frozen=True) -class PrepareOp(Statement): - """Prepare qubit slots (unprepared -> prepared).""" - - allocator: str - slots: tuple[int, ...] | None = None # None means all slots - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_prepare(self) - - -@dataclass(frozen=True) -class MeasureOp(Statement): - """Measure qubit slots.""" - - targets: tuple[SlotRef, ...] - results: tuple[BitRef, ...] = () - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_measure(self) - - def children(self) -> Sequence[ASTNode]: - return (*self.targets, *self.results) - - -@dataclass(frozen=True) -class AssignOp(Statement): - """Classical assignment.""" - - target: BitRef | str # Variable or bit reference - value: Expression - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_assign(self) - - def children(self) -> Sequence[ASTNode]: - nodes = [self.value] - if isinstance(self.target, ASTNode): - nodes.insert(0, self.target) - return nodes - - -@dataclass(frozen=True) -class BarrierOp(Statement): - """Synchronization barrier.""" - - allocators: tuple[str, ...] = () - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_barrier(self) - - -@dataclass(frozen=True) -class CommentOp(Statement): - """Comment in generated code.""" - - text: str - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_comment(self) - - -@dataclass(frozen=True) -class ReturnOp(Statement): - """Return statement.""" - - values: tuple[Expression, ...] - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_return(self) - - def children(self) -> Sequence[ASTNode]: - return self.values -``` - -### Control Flow - -```python -@dataclass(frozen=True) -class IfStmt(Statement): - """Conditional execution.""" - - condition: Expression - then_body: tuple[Statement, ...] - else_body: tuple[Statement, ...] = () - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_if(self) - - def children(self) -> Sequence[ASTNode]: - return (self.condition, *self.then_body, *self.else_body) - - -@dataclass(frozen=True) -class WhileStmt(Statement): - """While loop.""" - - condition: Expression - body: tuple[Statement, ...] - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_while(self) - - def children(self) -> Sequence[ASTNode]: - return (self.condition, *self.body) - - -@dataclass(frozen=True) -class ForStmt(Statement): - """For loop with iteration variable.""" - - variable: str - start: Expression - stop: Expression - step: Expression | None = None - body: tuple[Statement, ...] - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_for(self) - - def children(self) -> Sequence[ASTNode]: - nodes = [self.start, self.stop] - if self.step: - nodes.append(self.step) - nodes.extend(self.body) - return nodes - - -@dataclass(frozen=True) -class RepeatStmt(Statement): - """Repeat N times.""" - - count: int - body: tuple[Statement, ...] - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_repeat(self) - - def children(self) -> Sequence[ASTNode]: - return self.body - - -@dataclass(frozen=True) -class ParallelBlock(Statement): - """Parallel execution hint.""" - - body: tuple[Statement, ...] - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_parallel(self) - - def children(self) -> Sequence[ASTNode]: - return self.body -``` - -### References - -```python -@dataclass(frozen=True) -class SlotRef(ASTNode): - """Reference to a qubit slot in an allocator.""" - - allocator: str - index: int - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_slot_ref(self) - - def __str__(self) -> str: - return f"{self.allocator}[{self.index}]" - - -@dataclass(frozen=True) -class BitRef(ASTNode): - """Reference to a classical bit in a register.""" - - register: str - index: int - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_bit_ref(self) - - def __str__(self) -> str: - return f"{self.register}[{self.index}]" -``` - -### Expressions - -```python -class Expression(ASTNode, ABC): - """Base for all expressions.""" - - pass - - -@dataclass(frozen=True) -class LiteralExpr(Expression): - """Literal value (int, float, bool).""" - - value: int | float | bool - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_literal(self) - - -@dataclass(frozen=True) -class VarExpr(Expression): - """Variable reference.""" - - name: str - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_var(self) - - -@dataclass(frozen=True) -class BitExpr(Expression): - """Bit reference as expression (for conditions).""" - - ref: BitRef - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_bit_expr(self) - - def children(self) -> Sequence[ASTNode]: - return (self.ref,) - - -@dataclass(frozen=True) -class BinaryExpr(Expression): - """Binary operation.""" - - op: BinaryOp - left: Expression - right: Expression - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_binary(self) - - def children(self) -> Sequence[ASTNode]: - return (self.left, self.right) - - -@dataclass(frozen=True) -class UnaryExpr(Expression): - """Unary operation.""" - - op: UnaryOp - operand: Expression - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_unary(self) - - def children(self) -> Sequence[ASTNode]: - return (self.operand,) - - -class BinaryOp(Enum): - """Binary operators.""" - - # Arithmetic - ADD = auto() - SUB = auto() - MUL = auto() - DIV = auto() - # Comparison - EQ = auto() - NE = auto() - LT = auto() - LE = auto() - GT = auto() - GE = auto() - # Logical - AND = auto() - OR = auto() - XOR = auto() - # Bitwise - LSHIFT = auto() - RSHIFT = auto() - - -class UnaryOp(Enum): - """Unary operators.""" - - NOT = auto() - NEG = auto() -``` - -### Gate Kinds - -```python -class GateKind(Enum): - """All supported gate types.""" - - # Single-qubit Paulis - X = auto() - Y = auto() - Z = auto() - # Hadamard - H = auto() - # Phase gates - S = auto() - Sdg = auto() - T = auto() - Tdg = auto() - # Square root gates - SX = auto() - SY = auto() - SZ = auto() - SXdg = auto() - SYdg = auto() - SZdg = auto() - # Rotation gates (parameterized) - RX = auto() - RY = auto() - RZ = auto() - # Two-qubit gates - CX = auto() - CY = auto() - CZ = auto() - CH = auto() - # Two-qubit rotations - SXX = auto() - SYY = auto() - SZZ = auto() - SXXdg = auto() - SYYdg = auto() - SZZdg = auto() - RZZ = auto() - # Face rotations - F = auto() - Fdg = auto() - F4 = auto() - F4dg = auto() - - @property - def arity(self) -> int: - """Number of qubit arguments.""" - two_qubit = { - GateKind.CX, - GateKind.CY, - GateKind.CZ, - GateKind.CH, - GateKind.SXX, - GateKind.SYY, - GateKind.SZZ, - GateKind.SXXdg, - GateKind.SYYdg, - GateKind.SZZdg, - GateKind.RZZ, - } - return 2 if self in two_qubit else 1 - - @property - def is_parameterized(self) -> bool: - """Whether this gate takes angle parameters.""" - return self in {GateKind.RX, GateKind.RY, GateKind.RZ, GateKind.RZZ} -``` - -### Type Expressions - -```python -@dataclass(frozen=True) -class TypeExpr(ASTNode): - """Type expression for return types and declarations.""" - - pass - - -@dataclass(frozen=True) -class QubitType(TypeExpr): - """Single qubit type.""" - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_qubit_type(self) - - -@dataclass(frozen=True) -class BitType(TypeExpr): - """Single classical bit type.""" - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_bit_type(self) - - -@dataclass(frozen=True) -class ArrayType(TypeExpr): - """Array type with element type and size.""" - - element: TypeExpr - size: int - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_array_type(self) - - def children(self) -> Sequence[ASTNode]: - return (self.element,) - - -@dataclass(frozen=True) -class AllocatorType(TypeExpr): - """Qubit allocator type with capacity.""" - - capacity: int - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_allocator_type(self) -``` - ---- - -## Visitor Protocol - -```python -from typing import TypeVar, Protocol - -T = TypeVar("T") - - -class ASTVisitor(Protocol[T]): - """Protocol for AST visitors.""" - - # Program structure - def visit_program(self, node: Program) -> T: ... - def visit_allocator_decl(self, node: AllocatorDecl) -> T: ... - def visit_register_decl(self, node: RegisterDecl) -> T: ... - - # Statements - def visit_gate(self, node: GateOp) -> T: ... - def visit_prepare(self, node: PrepareOp) -> T: ... - def visit_measure(self, node: MeasureOp) -> T: ... - def visit_assign(self, node: AssignOp) -> T: ... - def visit_barrier(self, node: BarrierOp) -> T: ... - def visit_comment(self, node: CommentOp) -> T: ... - def visit_return(self, node: ReturnOp) -> T: ... - - # Control flow - def visit_if(self, node: IfStmt) -> T: ... - def visit_while(self, node: WhileStmt) -> T: ... - def visit_for(self, node: ForStmt) -> T: ... - def visit_repeat(self, node: RepeatStmt) -> T: ... - def visit_parallel(self, node: ParallelBlock) -> T: ... - - # References - def visit_slot_ref(self, node: SlotRef) -> T: ... - def visit_bit_ref(self, node: BitRef) -> T: ... - - # Expressions - def visit_literal(self, node: LiteralExpr) -> T: ... - def visit_var(self, node: VarExpr) -> T: ... - def visit_bit_expr(self, node: BitExpr) -> T: ... - def visit_binary(self, node: BinaryExpr) -> T: ... - def visit_unary(self, node: UnaryExpr) -> T: ... - - # Types - def visit_qubit_type(self, node: QubitType) -> T: ... - def visit_bit_type(self, node: BitType) -> T: ... - def visit_array_type(self, node: ArrayType) -> T: ... - def visit_allocator_type(self, node: AllocatorType) -> T: ... - - -class BaseVisitor(Generic[T]): - """Base visitor with default traversal behavior.""" - - def visit(self, node: ASTNode) -> T: - """Dispatch to appropriate visit method.""" - return node.accept(self) - - def visit_children(self, node: ASTNode) -> list[T]: - """Visit all children and collect results.""" - return [self.visit(child) for child in node.children()] - - # Default implementations that just visit children - def visit_program(self, node: Program) -> T: - self.visit_children(node) - return self.default_result() - - # ... etc for all node types ... - - def default_result(self) -> T: - """Default result when no specific handling.""" - return None # type: ignore -``` - ---- - -## Example: AST for QEC Program - -```python -# The SLR code: -# def main(): -# base = QAlloc(17) -# data = base.child(9) -# ancilla = base.child(8) -# data.prepare_all() -# ancilla.prepare_all() -# H(data[0]) -# CX(data[0], data[1]) -# Measure(ancilla) > syndrome - -# As AST: -program = Program( - name="main", - allocator=AllocatorDecl(name="base", capacity=17), - declarations=( - AllocatorDecl(name="data", capacity=9, parent="base"), - AllocatorDecl(name="ancilla", capacity=8, parent="base"), - RegisterDecl(name="syndrome", size=8), - ), - body=( - PrepareOp(allocator="data"), - PrepareOp(allocator="ancilla"), - GateOp( - gate=GateKind.H, - targets=(SlotRef("data", 0),), - ), - GateOp( - gate=GateKind.CX, - targets=(SlotRef("data", 0), SlotRef("data", 1)), - ), - MeasureOp( - targets=tuple(SlotRef("ancilla", i) for i in range(8)), - results=tuple(BitRef("syndrome", i) for i in range(8)), - ), - ), -) -``` - ---- - -## Integration with QAlloc - -The AST is designed to work seamlessly with the QAlloc system: - -### Allocator Hierarchy in AST - -```python -# Parent-child relationships are explicit -AllocatorDecl(name="base", capacity=100) -AllocatorDecl(name="data", capacity=7, parent="base") -AllocatorDecl(name="ancilla", capacity=6, parent="base") -``` - -### Slot State Validation - -The `QubitStateValidator` can work directly on the AST: - -```python -class ASTStateValidator(BaseVisitor[None]): - """Validate qubit states on AST.""" - - def __init__(self): - self.slot_states: dict[tuple[str, int], SlotState] = {} - self.violations: list[StateViolation] = [] - - def visit_prepare(self, node: PrepareOp) -> None: - # Mark slots as prepared - if node.slots is None: - # prepare_all - need allocator capacity - ... - else: - for slot in node.slots: - self.slot_states[(node.allocator, slot)] = SlotState.PREPARED - - def visit_gate(self, node: GateOp) -> None: - # Validate all targets are prepared - for target in node.targets: - state = self.slot_states.get((target.allocator, target.index), SlotState.UNPREPARED) - if state == SlotState.UNPREPARED: - self.violations.append(StateViolation(...)) - - def visit_measure(self, node: MeasureOp) -> None: - # Mark slots as unprepared - for target in node.targets: - self.slot_states[(target.allocator, target.index)] = SlotState.UNPREPARED -``` - ---- - -## Conversion Functions - -### From Current SLR to AST - -```python -def slr_to_ast(block: SLRBlock) -> Program: - """Convert current SLR block to AST.""" - converter = SLRToASTConverter() - return converter.convert(block) - - -class SLRToASTConverter: - """Converts SLR objects to AST nodes.""" - - def convert(self, block: SLRBlock) -> Program: - declarations = [] - body = [] - - # Convert variables - for var in block.vars: - declarations.append(self.convert_var(var)) - - # Convert operations - for op in block.ops: - body.append(self.convert_op(op)) - - return Program( - name=getattr(block, "block_name", "main"), - allocator=None, # Legacy mode - no base allocator - declarations=tuple(declarations), - body=tuple(body), - ) - - def convert_var(self, var) -> Declaration: - if isinstance(var, QReg): - # Convert to legacy allocator-like declaration - return AllocatorDecl(name=var.sym, capacity=var.size) - elif isinstance(var, CReg): - return RegisterDecl(name=var.sym, size=var.size, is_result=var.result) - elif isinstance(var, QAlloc): - return AllocatorDecl( - name=var.name, - capacity=var.capacity, - parent=var.parent.name if var.parent else None, - ) - # ... etc - - def convert_op(self, op) -> Statement: - op_name = type(op).__name__ - - if op_name in GATE_NAMES: - return self.convert_gate(op) - elif op_name == "Measure": - return self.convert_measure(op) - elif op_name in ("Prep", "Init", "Reset"): - return self.convert_prepare(op) - elif op_name == "If": - return self.convert_if(op) - # ... etc -``` - -### From AST to Current SLR - -```python -def ast_to_slr(program: Program) -> SLRBlock: - """Convert AST to current SLR objects for execution.""" - converter = ASTToSLRConverter() - return converter.convert(program) -``` - ---- - -## Code Generation from AST - -Each target gets a visitor: - -```python -class QASMGenerator(BaseVisitor[str]): - """Generate QASM from AST.""" - - def visit_program(self, node: Program) -> str: - lines = ["OPENQASM 2.0;", 'include "qelib1.inc";', ""] - - # Declarations - for decl in node.declarations: - lines.append(self.visit(decl)) - - lines.append("") - - # Body - for stmt in node.body: - lines.append(self.visit(stmt)) - - return "\n".join(lines) - - def visit_allocator_decl(self, node: AllocatorDecl) -> str: - return f"qreg {node.name}[{node.capacity}];" - - def visit_register_decl(self, node: RegisterDecl) -> str: - return f"creg {node.name}[{node.size}];" - - def visit_gate(self, node: GateOp) -> str: - gate_name = node.gate.name.lower() - targets = ", ".join(str(t) for t in node.targets) - if node.params: - params = ", ".join(str(p) for p in node.params) - return f"{gate_name}({params}) {targets};" - return f"{gate_name} {targets};" - - # ... etc - - -class GuppyGenerator(BaseVisitor[str]): - """Generate Guppy code from AST.""" - - # Similar structure, different output format - - -class HUGRGenerator(BaseVisitor[HUGRNode]): - """Generate HUGR from AST.""" - - # Returns HUGR IR nodes instead of strings -``` - ---- - -## Implementation Plan - -### Phase 1: Core AST Nodes - -1. Define all node dataclasses in `pecos/slr/ast/nodes.py` -2. Define visitor protocol in `pecos/slr/ast/visitor.py` -3. Implement `BaseVisitor` with default traversal - -### Phase 2: Conversion - -1. Implement `SLRToASTConverter` for current SLR → AST -2. Implement `ASTToSLRConverter` for AST → current SLR -3. Add tests for round-trip conversion - -### Phase 3: Analysis - -1. Port `QubitStateValidator` to work on AST -2. Add more analysis passes (unused variables, unreachable code, etc.) -3. Add pretty-printer for debugging - -### Phase 4: Code Generation - -1. Migrate QASM generator to use AST -2. Migrate Guppy generator to use AST -3. Add new generators as needed - -### Phase 5: DSL Integration - -1. Consider new DSL syntax that builds AST directly -2. Add builder pattern for programmatic AST construction -3. Integration with IDE tooling - ---- - -## Open Questions - -1. **Span tracking**: Should we track full spans (start + end) or just start locations? - -2. **Error recovery**: Should AST support partial/invalid trees for better error reporting? - -3. **Macro expansion**: How to handle QEC library blocks (Steane, etc.) that expand to multiple operations? - -4. **Metadata**: What additional metadata should nodes carry (e.g., optimization hints)? - -5. **Serialization**: Should AST be serializable to JSON/protobuf for tooling? - ---- - -## Summary - -The SLR AST provides: - -- **Clean structure**: Immutable, typed nodes with uniform interface -- **Easy analysis**: Visitor pattern for traversal and transformation -- **QAlloc integration**: First-class support for allocator hierarchy and slot states -- **Multi-target codegen**: One AST → QASM, Guppy, HUGR, etc. -- **Backward compatibility**: Conversion to/from current SLR objects diff --git a/design/proposals/slr-qubit-allocators.md b/design/proposals/slr-qubit-allocators.md deleted file mode 100644 index 0923e05f7..000000000 --- a/design/proposals/slr-qubit-allocators.md +++ /dev/null @@ -1,730 +0,0 @@ -# SLR Qubit Allocator Proposal - - - -## Status - -**Design decisions finalized.** Ready for implementation. - ---- - -## Motivation - -SLR needs to bridge two different models of qubit management: - -1. **QASM model**: Static registers declared upfront (`qreg q[5];`), all qubits exist from program start -2. **Guppy model**: Dynamic allocation with linear types (`q = qubit()`), qubits appear on demand - -Both have drawbacks: -- QASM's static registers lack ownership semantics and lifecycle tracking -- Guppy's dynamic allocation feels disconnected from physical hardware constraints ("qubits from nowhere") - -### The Allocator Model - -Inspired by Zig's allocator pattern and NASA's Power of 10 rules (particularly Rule 3: no dynamic allocation after initialization), we propose a hierarchical qubit allocator model that: -- Grounds allocation in physical resource constraints (total qubit budget declared upfront) -- Provides explicit ownership and natural scoping -- Tracks qubit slot states (unprepared vs prepared) -- Maintains array/register-oriented access patterns (effectively implementing QRegs) -- Enables compiler optimizations through abstracted physical identity - -### NASA Power of 10 Alignment - -| Power of 10 Rule | Allocator Model | -|------------------|-----------------| -| Rule 3: No dynamic allocation after init | Base allocator declares total capacity in `main` | -| Rule 6: Smallest possible scope | Child allocators scoped to functions/blocks | -| Rule 2: Fixed loop bounds | Allocator capacity is bounded and known | -| Predictability | All resource usage visible from `main` | - ---- - -## Core Concepts - -### 1. Base Allocator - -Every program declares a base allocator in `main` representing the total physical qubit capacity: - -```python -def main(): - base = QAlloc(capacity=100) # "I have 100 physical qubits" - - # All other allocators derive from this - data = base.child(7) - ancilla = base.child(6) - - run_qec(data, ancilla) -``` - -This is the root of all qubit ownership. It represents the actual hardware constraint. Functions that need qubits receive allocators (or children thereof) as parameters. - -### 2. Child Allocators (Hierarchical Ownership) - -Any allocator can create child allocators that reserve slots from its capacity: - -```python -base = QAlloc(100) - -# First level partitioning -data = base.child(7) # Reserve 7 slots for data -ancilla = base.child(6) # Reserve 6 slots for ancilla -# base now has 87 available - -# Nested partitioning - any allocator can have children -workspace = ancilla.child(2) # Borrow 2 from ancilla -# ancilla now has 4 available -``` - -**Key properties:** -- Child allocators exclusively reserve slots from their parent -- Parent cannot use reserved slots until child releases them -- Children can create their own children (unlimited depth) -- Natural scoping: unreturned allocators automatically release to parent - -### 3. Slots and Qubit Association - -An allocator has N **slots**. Each slot is in one of two states: - -``` -┌─────────────┐ -│ unprepared │ ← Not ready for gates (initial state, or after measurement) -└──────┬──────┘ - │ prepare() ← Request qubit, associate with slot, initialize to |0⟩ - ▼ -┌─────────────┐ -│ prepared │ ← Ready for gates -└──────┬──────┘ - │ measure() - ▼ -┌─────────────┐ -│ unprepared │ ← Back to unprepared -└─────────────┘ -``` - -Two states, not three. Whether a slot has "never been used" or "was measured" doesn't matter - both are **unprepared** and require `prepare()` before gates. - -**Key insight**: `prepare()` means "request a qubit to be associated with this slot and prepared for use." The slot becomes usable. After measurement, the slot returns to unprepared. - -**Rules (enforced at compile time):** -- Gates can only be applied to **prepared** slots → compile error if unprepared -- Measurement transitions slots to **unprepared** -- Slots can be prepared individually or in batches at different times - -### 4. Slot-Based Access (Not Physical Identity) - -Qubits are accessed through their allocator via slot indices: - -```python -ancilla = base.child(4) -ancilla.prepare(0, 1) # Prepare slots 0 and 1 - -H(ancilla[0]) # Apply H to slot 0 -CNOT(ancilla[0], ancilla[1]) # CNOT between slots 0 and 1 -``` - -**Important**: `ancilla[0]` refers to "slot 0 in the ancilla allocator" - not a fixed physical qubit. After measure + prepare cycles, the physical qubit backing slot 0 may change. The compiler manages the mapping. - -```python -ancilla.prepare_all() -# ancilla[0] → physical qubit 42 - -Measure(ancilla) -ancilla.prepare_all() -# ancilla[0] → might now be physical qubit 37 (compiler's choice) -``` - -This abstraction enables: -- Qubit recycling and reuse optimizations -- Routing around defective qubits -- Connectivity-aware mapping - -The programmer thinks in logical slots; the compiler handles physical mapping. - -### 5. Ownership and Natural Scoping - -Allocators follow ownership rules similar to Zig: - -```python -def syndrome_round(ancilla: QAlloc[6]) -> Bits: - ancilla.prepare_all() - # ... syndrome extraction ... - return Measure(ancilla) - # ancilla NOT returned → consumed → released to parent - - -def apply_logical_gate(data: QAlloc[7]) -> QAlloc[7]: - # ... apply gate ... - return data # returned → caller retains ownership -``` - -**Scoping rules:** -- If an allocator is not returned from a function/block, it is automatically released -- Released resources flow back to the parent allocator -- No explicit `free()` or `release()` needed - scope handles it - ---- - -## API Design - -### QAlloc Class - -```python -class QAlloc[N]: - """ - A qubit allocator managing N qubit slots. - - Type parameter N is the capacity (known at compile time for type checking, - but can also be runtime-determined). - """ - - # --- Creation --- - - def __init__(self, capacity: int): - """Create a base allocator with given capacity.""" - ... - - def child(self, size: int) -> QAlloc: - """ - Create a child allocator with `size` slots. - - Reserves `size` qubits from this allocator's available pool. - Raises if insufficient capacity available. - """ - ... - - # --- Lifecycle Operations --- - - def prepare(self, *indices: int) -> None: - """Prepare specific slots (unprepared → prepared).""" - ... - - def prepare_all(self) -> None: - """Prepare all slots in this allocator.""" - ... - - # --- Access --- - - def __getitem__(self, index: int) -> QubitRef: - """ - Access slot `index` for use in gates. - - Returns a QubitRef that can be passed to gate operations. - The qubit must be in 'prepared' state. - """ - ... - - # --- Information --- - - @property - def capacity(self) -> int: - """Total number of slots in this allocator.""" - ... - - @property - def available(self) -> int: - """Number of slots not reserved by children.""" - ... - - def state(self, index: int) -> SlotState: - """Get the state of a specific slot (unprepared or prepared).""" - ... -``` - -### QubitRef (Reference to a Slot) - -```python -class QubitRef: - """ - A reference to a qubit slot in an allocator. - - Used as arguments to gate operations. Not a standalone qubit - - always tied to its parent allocator. - """ - - allocator: QAlloc - index: int -``` - -### SlotState Enum - -```python -class SlotState(Enum): - UNPREPARED = "unprepared" # Not ready for gates (initial or post-measurement) - PREPARED = "prepared" # Ready for gate operations -``` - -Two states only. Simple. - -### Gate Operations - -Gates accept `QubitRef` arguments: - -```python -# Single qubit gates -H(alloc[0]) -X(alloc[1]) -Rz(alloc[2], angle=0.5) - -# Two qubit gates -CNOT(alloc[0], alloc[1]) -CZ(data[0], ancilla[0]) # Can span different allocators - -# Measurement (transitions to unprepared) -result = Measure(alloc[0]) # Single qubit -results = Measure(alloc) # All qubits in allocator -results = Measure(alloc[0:3]) # Slice of allocator -``` - ---- - -## Edge Cases and Considerations - -### 1. Cross-Allocator Entanglement - -**Scenario**: Qubits from different allocators become entangled. - -```python -data = base.child(7) -ancilla = base.child(6) - -data.prepare_all() -ancilla.prepare_all() - -# Entangle across allocators -CNOT(data[0], ancilla[0]) -``` - -**Decision**: Allowed. Allocators manage ownership and slot lifecycle, not entanglement tracking. If `ancilla` is released while entangled with `data`, the slots return to the parent (unprepared). No compiler warning needed - we're not tracking entanglement. - -### 2. Partial Measurement - -**Scenario**: Only some slots in an allocator are measured. - -```python -ancilla = base.child(4) -ancilla.prepare_all() - -# Measure only slots 0 and 1 -result = Measure(ancilla[0], ancilla[1]) - -# ancilla[0], ancilla[1] are now unprepared -# ancilla[2], ancilla[3] are still prepared -``` - -**Resolution**: The allocator tracks per-slot state. This is fully supported. - -### 3. Capacity Exhaustion - -**Scenario**: Requesting more qubits than available. - -```python -base = QAlloc(10) -a = base.child(6) -b = base.child(6) # ERROR: only 4 available -``` - -**Resolution**: -- **Compile-time**: If sizes are known statically, this is a compile error -- **Runtime**: Raises an exception (e.g., `AllocationError`) - -The type system can help: `QAlloc[N]` carries capacity information. - -### 4. Returning Partial Allocators - -**Scenario**: Function receives an allocator, creates children, returns some. - -```python -def split_and_process(alloc: QAlloc[10]) -> QAlloc[3]: - a = alloc.child(3) - b = alloc.child(7) - - process(b) # b consumed (not returned) - - return a # Only a returned - COMPILE ERROR -``` - -**Decision**: Must return parent OR all children. Enforced at compile time. - -If you create children from a received allocator, you must either: -1. Return the parent allocator (children are released back to it) -2. Return ALL children (parent is consumed, all resources accounted for) - -This ensures clear resource contracts and prevents orphaned slots. - -```python -# Valid: return parent -def process_and_return(alloc: QAlloc[10]) -> QAlloc[10]: - child = alloc.child(5) - use(child) # child released back to alloc - return alloc - - -# Valid: return all children -def split_evenly(alloc: QAlloc[10]) -> tuple[QAlloc[5], QAlloc[5]]: - a = alloc.child(5) - b = alloc.child(5) - return a, b # alloc consumed, all slots accounted for -``` - -### 5. Conditional Allocation - -**Scenario**: Allocation inside conditional blocks. - -```python -base = QAlloc(10) - -if condition: - extra = base.child(5) - extra.prepare_all() - # ... use extra ... - # extra released at end of block -else: - pass # no allocation -``` - -**Resolution**: This is fine. The allocation is scoped to the if-block. After the block, resources are back in `base`. Both branches end with `base` having the same available capacity. - -### 6. Allocation in Loops - -**Scenario**: Creating allocators inside loops. - -```python -base = QAlloc(10) - -for round in range(1000): - ancilla = base.child(4) - ancilla.prepare_all() - syndrome = Measure(ancilla) - # ancilla released, back to base - - # Next iteration can allocate again -``` - -**Resolution**: This is a primary use case. Each iteration allocates, uses, and releases. The pool is recycled. - -### 7. Escaping References (Zig-inspired) - -**Scenario**: Storing a `QubitRef` beyond the allocator's lifetime. - -```python -stored_ref = None - - -def bad_function(alloc: QAlloc[5]): - global stored_ref - alloc.prepare_all() - stored_ref = alloc[0] # Store reference - # alloc released at end - - -bad_function(base.child(5)) -H(stored_ref) # ERROR: dangling reference -``` - -**Decision**: `QubitRef` is ephemeral, like Zig slices/pointers into allocator memory. - -In Zig, when you get memory from an allocator, you get a slice that's valid only while the allocator owns that memory. Similarly, `QubitRef` is valid only while its allocator is alive. - -- `alloc[i]` creates a `QubitRef` for immediate use in gate operations -- `QubitRef` should not be stored in data structures or globals -- The compile-time analysis detects when a `QubitRef` escapes its allocator's scope -- If used after allocator release: compile error (if detectable) or runtime error - -### 8. Allocator Merging - -**Scenario**: Combining two sibling allocators. - -```python -base = QAlloc(10) -a = base.child(3) -b = base.child(3) - -# Can we merge a and b into a single allocator of 6? -merged = merge(a, b) # ??? -``` - -**Resolution**: Not supported in initial design. If you need a combined view: -- Release both back to parent -- Allocate a new child of desired size - -Merging adds complexity (different qubit states, index remapping). YAGNI for now. - -### 9. Slicing Allocators - -**Scenario**: Creating a view into part of an allocator. - -```python -data = base.child(7) -first_three = data[0:3] # Is this a new allocator or just refs? -``` - -**Resolution**: Two options: - -**Option A**: Slicing returns a tuple of `QubitRef` -```python -first_three = (data[0], data[1], data[2]) # Just refs -``` - -**Option B**: Slicing creates a child allocator (view) -```python -first_three = data.slice(0, 3) # New child allocator -``` - -**Recommendation**: Option A for simplicity. Slicing is just syntactic sugar for multiple refs. Use explicit `child()` for ownership transfer. - -### 10. Classical Data - Do We Need Allocators? - -**Decision**: No. Keep `CReg` as-is. - -Classical data doesn't have: -- The same physical scarcity constraints -- Lifecycle states (bits don't need "preparation") -- The same ownership complexity - -Classical registers remain as simple `CReg` arrays. The allocator pattern is specifically for quantum resources. - -### 11. Interaction with Existing SLR Constructs - -The allocator model effectively implements `QReg` with additional semantics: - -| Current | New | -|---------|-----| -| `QReg("q", 5)` | `q = parent.child(5)` | -| `q[0]` (Qubit) | `q[0]` (QubitRef) | -| `Prep(q[0])` | `q.prepare(0)` | -| `Measure(q[0])` | `Measure(q[0])` (unchanged) | - -**Key difference**: Base allocator declared in main, passed to functions: - -```python -def main(): - base = QAlloc(100) # Declare capacity in main - - data = base.child(7) - ancilla = base.child(6) - - data.prepare_all() - ancilla.prepare_all() - - run_qec_rounds(data, ancilla) - - -def run_qec_rounds(data: QAlloc[7], ancilla: QAlloc[6]): - # Receives allocators as parameters - ... -``` - -This replaces the current pattern where `QReg` is declared inside `Block` classes. - ---- - -## Type System Integration - -### Static Capacity Tracking - -```python -QAlloc[N] # Allocator with capacity N - - -def syndrome_extraction(data: QAlloc[7], ancilla: QAlloc[6]) -> tuple[Bits, QAlloc[7]]: - # Type system knows: - # - data has 7 slots - # - ancilla has 6 slots - # - ancilla is consumed (not in return type) - # - data is returned (ownership transferred back) - ... -``` - -### Lowering to Target Formats - -| Target | Allocator Becomes | -|--------|-------------------| -| QASM 2.0 | `qreg` declarations with index mapping | -| QASM 3.0 | `qubit[N]` arrays | -| Guppy | `array[qubit, N]` with linear ownership | -| HUGR | Qubit allocation ops with region tracking | -| QIR | Qubit allocation intrinsics | - ---- - -## Implementation Plan - -### Phase 1: Core Data Structures - -1. Define `QAlloc` class with: - - Capacity tracking - - Child creation and management - - Per-slot state tracking (unprepared/prepared) - -2. Define `QubitRef` class as thin wrapper - -3. Define `SlotState` enum (two states: unprepared, prepared) - -### Phase 2: Integration with SLR Operations - -1. Modify gate classes to accept `QubitRef` -2. Add `prepare()` method/gate -3. Modify `Measure` to transition slots to unprepared -4. Update `Block` to require base allocator declaration - -### Phase 3: Code Generation Updates - -1. Update `SlrConverter` to handle allocator-based programs -2. Update QASM generator to map allocators to registers -3. Update Guppy generator to map allocators to arrays with linear semantics -4. Update resource planner to understand allocator hierarchy - -### Phase 4: Validation and Analysis - -1. Add compile-time checks for: - - Base allocator requirement - - Capacity overflow detection - - Lifecycle violations (gate on unprepared slot) - - Ownership violations (use after release) - -2. Add warnings for: - - Releasing entangled qubits - - Unused allocator capacity - -**Integration Points for State Checking:** - -The existing data flow analysis infrastructure can be leveraged: -- `DataFlowAnalyzer` (data_flow.py:37-354) - already tracks consumption and replacement -- `IRAnalyzer` (ir_analyzer.py:114) - integration point after `_integrate_data_flow()` -- `IRBuilder` (ir_builder.py:3078, 4137) - gate conversion with validation -- `ScopeManager` (scope_manager.py:27-145) - runtime state tracking - -A new `QubitStateValidator` module would: -1. Initialize from DataFlowAnalysis with all elements as "unprepared" -2. Mark elements as "prepared" when `Prep`/`Init`/`Reset` operations occur -3. Mark elements as "unprepared" when `Measure` operations occur -4. Validate that gates only operate on "prepared" elements - -### Phase 5: Documentation and Migration - -1. Document the allocator model -2. Provide migration guide from `QReg` to allocators -3. Update examples - ---- - -## Design Decisions Summary - -| Question | Decision | -|----------|----------| -| Slot states | Two: `unprepared` and `prepared` (no separate "dirty") | -| Prepare syntax | Method: `alloc.prepare(0, 1, 2)` or `alloc.prepare_all()` | -| Gate on unprepared slot | Compile-time error | -| Base allocator location | Declared in `main`, passed to functions | -| Returning allocators | Must return parent OR all children | -| Cross-allocator entanglement | Allowed, not tracked | -| Classical registers | Keep `CReg` as-is | -| QubitRef lifetime | Ephemeral, Zig-inspired (no escaping scope) | -| Philosophy | NASA Power of 10 inspired (no dynamic alloc after init) | - ---- - -## Implementation Decisions - -| Question | Decision | -|----------|----------| -| Migration | Dual support: `QReg` as alias/wrapper for `QAlloc` | -| Naming | `QAlloc` (follows `QReg`/`CReg` convention) | -| Prepare return | `void` - keeps refs ephemeral, allocator is source of truth | - ---- - -## Complete Example: QEC Round - -```python -def main(): - # Declare physical resource budget - base = QAlloc(capacity=17) - - # Partition into logical groupings - data = base.child(9) # 9 data qubits for surface code - ancilla = base.child(8) # 8 ancilla for syndrome extraction - - # Initialize data qubits - data.prepare_all() - encode_logical_zero(data) - - # Run QEC rounds - for round in range(100): - syndrome = extract_syndrome(data, ancilla) - if needs_correction(syndrome): - apply_correction(data, syndrome) - - # Final readout - result = decode_and_measure(data) - return result - - -def extract_syndrome(data: QAlloc[9], ancilla: QAlloc[8]) -> Bits: - """ - Extract syndrome without consuming data. - Ancilla is consumed (not returned). - """ - ancilla.prepare_all() - - # X stabilizers - for i in range(4): - H(ancilla[i]) - CNOT(ancilla[i], data[stabilizer_x_targets(i)]) - H(ancilla[i]) - - # Z stabilizers - for i in range(4): - CNOT(data[stabilizer_z_targets(i)], ancilla[4 + i]) - - # Measure all ancilla - slots become unprepared - syndrome = Measure(ancilla) - - # ancilla not returned → released back to caller's scope - # data returned implicitly via not being consumed - return syndrome - - -def encode_logical_zero(data: QAlloc[9]) -> QAlloc[9]: - """ - Encode logical |0⟩. Returns the data allocator. - """ - # data already prepared by caller - H(data[0]) - CNOT(data[0], data[1]) - # ... encoding circuit ... - return data # Ownership returned to caller - - -def decode_and_measure(data: QAlloc[9]) -> Bits: - """ - Decode and measure. Consumes the data allocator. - """ - # ... decoding circuit ... - result = Measure(data) - # data not returned → consumed - return result -``` - -### What This Demonstrates - -1. **Base in main**: `QAlloc(17)` declares total capacity upfront -2. **Child allocators as "registers"**: `data` and `ancilla` are like QRegs -3. **Slot preparation**: `prepare_all()` makes slots usable -4. **Natural consumption**: `ancilla` not returned from `extract_syndrome` → released -5. **Explicit return for ownership**: `encode_logical_zero` returns `data` to maintain ownership -6. **Loop reuse**: Each round re-prepares ancilla, reusing the same slots - ---- - -## Summary - -The qubit allocator model provides: - -- **Physical grounding**: Resources come from a declared capacity, not thin air -- **Hierarchical ownership**: Clear parent-child relationships with natural scoping -- **Lifecycle tracking**: Two states (unprepared/prepared) enforced at compile time -- **Slot abstraction**: Logical indices, not physical identity - enabling optimizations -- **Clean semantics**: Ownership rules similar to Rust/Zig for resource safety - -This bridges QASM's register model and Guppy's linear types while feeling more connected to physical hardware constraints. diff --git a/design/python-classical-interpreter-suspected-bugs.md b/design/python-classical-interpreter-suspected-bugs.md deleted file mode 100644 index ce8060449..000000000 --- a/design/python-classical-interpreter-suspected-bugs.md +++ /dev/null @@ -1,54 +0,0 @@ -# Python PhirClassicalInterpreter -- Suspected Bugs - -Found during the Rust reimplementation and fuzz testing. - -Bugs #1 and #2 are the same class of issue as -[PECOS-packages/PECOS#213](https://github.com/PECOS-packages/PECOS/issues/213): -PECOS dtype constructors reject values outside the type range instead of -masking/wrapping. PR #214 fixed the specific operator overload case but the -underlying dtype overflow issue remains. - -## 1. Overflow rejected for values that fit the register but not the dtype - -**Status:** FIXED (dtype constructors now truncate instead of rejecting) - -**Description:** `assign_int` converts the value through the PECOS dtype constructor (`dtype(val)`) before masking to register size. If the value exceeded the dtype's range, Python threw `OverflowError`. Fixed by changing dtype constructors to accept `i64` and truncate via cast. - ---- - -## 2. Bitwise NOT overflows when assigning cross-type - -**Status:** FIXED (dtype constructors now truncate instead of rejecting) - -**Description:** `~m` where `m` is `u32 size=1` produced `u32(4294967295)`. Assigning to an `i32` variable did `i32(4294967295)` which threw `OverflowError`. Fixed by the same dtype constructor change. - ---- - -## 3. `PhirModel.model_validate` rejects valid PHIR programs with `Result` cop - -**Confidence:** High (but in the `phir` pydantic model, not the interpreter itself) -**File:** `python/quantum-pecos/src/pecos/classical_interpreters/phir_classical_interpreter.py` -**Line:** 101-102 - -**Description:** When `phir_validate=True` (default), the interpreter validates programs through `PhirModel.model_validate()` from the `phir` pydantic package. This validator rejects the `Result` classical operation, which is a valid PECOS-specific extension used in many test programs. - -**Example:** Programs with `{"cop": "Result", "args": ["m"], "returns": ["c"]}` fail pydantic validation even though they execute correctly. - -**Impact:** Users must set `phir_validate=False` to run programs with `Result` operations when using the Python interpreter. The Rust interpreter's serde parser handles these correctly. - ---- - -## Design questions (not clear-cut bugs) - -### Signed types not masked to register size - -**File:** `python/quantum-pecos/src/pecos/classical_interpreters/phir_classical_interpreter.py` -**Line:** 345-349 - -`assign_int()` only masks unsigned types to the register's declared `size`. Signed types are stored at the full dtype width. The code has a comment: `# (only valid for unsigned data types)` -- suggesting this was a deliberate choice. - -The PHIR spec says "assigning 5 to a 2-bit variable stores only the lower 2 bits" with no unsigned-only qualifier, but there may be good reasons for treating signed types differently (sign-extension from narrow widths is lossy). - -### Shift by type width is a no-op - -`u32(1) << 32` gives `u32(1)` instead of `u32(0)`. The PECOS dtype uses native hardware shift semantics (shift amount modulo type width). This matches x86/ARM behavior but not mathematical semantics. Whether the PHIR spec expects hardware or mathematical shift behavior is unclear. diff --git a/design/rust-phir-classical-interpreter.md b/design/rust-phir-classical-interpreter.md deleted file mode 100644 index ebfd0c378..000000000 --- a/design/rust-phir-classical-interpreter.md +++ /dev/null @@ -1,298 +0,0 @@ -# Rust PhirClassicalInterpreter -- Drop-in Replacement Spec - -## Goal - -Build a Rust `PhirClassicalInterpreter` that is a drop-in replacement for the Python -`PhirClassicalInterpreter` in `HybridEngine`. The Python PHIR code is the spec -- the -Rust version must have identical behavior. - -Eventually we move to the full Rust sim() system, but this is the first step: replace -the Python classical interpreter internals while keeping the Python `HybridEngine` -orchestration. - -## Architecture - -``` -crates/pecos-phir-json/ -- Rust logic lives here (reuse existing internals) -python/pecos-rslib/ -- PyO3 wrapper lives here (new pyclass) -``` - -The Rust interpreter reuses existing components from `pecos-phir-json/src/v0_1/`: -- `ast.rs` -- PHIR JSON parsing -- `environment.rs` -- variable storage, bit ops, types -- `expression.rs` -- expression evaluation -- `operations.rs` -- classical op handling logic (adapt) - -The PyO3 layer in `pecos-rslib` exposes it as a `#[pyclass]` implementing the -`ClassicalInterpreterProtocol`. - -## Python Protocol - -From `python/quantum-pecos/src/pecos/protocols.py`, the interpreter must satisfy: - -```python -class ClassicalInterpreterProtocol(Protocol): - program: Any - foreign_obj: Any - phir_validate: bool - - def reset(self) -> None: ... - def init(self, program: str | dict | QuantumCircuit, foreign_obj: object | None = None) -> int: ... - def shot_reinit(self) -> None: ... - def execute(self, sequence: Sequence | None) -> Generator[list[QOp | MOp], Any, None]: ... - def receive_results(self, qsim_results: list[dict]) -> None: ... - def results(self, *, return_int: bool = True) -> dict: ... -``` - -Additional methods called by HybridEngine but not in the protocol: -```python -def add_cvar(self, cvar: str, dtype: type, size: int) -> None: ... -def result_bits(self, bits: Iterable, *, filter_private: bool = True) -> dict: ... -``` - -## Call Ordering in HybridEngine - -``` -INITIALIZATION: - outer = PhirClassicalInterpreter() - inner = PhirClassicalInterpreter() - inner.phir_validate = outer.phir_validate - - num_qubits = outer.init(program, foreign_object) - inner.init(program, foreign_object) # same program - machine.init(num_qubits) - -PER-SHOT: - outer.shot_reinit() - inner.shot_reinit() - for i in range(num_qubits): - inner.add_cvar(f"__q{i}__", pc.dtypes.i64, 1) # private qubit vars - - EXECUTION LOOP: - for buffered_ops in outer.execute(outer.program.ops): - noisy_ops = op_processor.process(buffered_ops) - measurements.clear() - for noisy_qops in inner.execute(noisy_ops): - temp_meas = qsim.run(noisy_qops) - inner.receive_results(temp_meas) - measurements.extend(temp_meas) - transmit_meas = inner.result_bits(measurements) - outer.receive_results([transmit_meas]) - - RESULTS: - shot_results = outer.results(return_int=return_int) -``` - -## Data Flow - -``` -PHIR JSON str/dict - | - v -outer.init() --> parse JSON, validate, build internal AST, init env - | return num_qubits - v -outer.execute(program.ops) - | - | yields: list[QOp | MOp] (batches ending at measurements) - v -op_processor.process(buffered_ops) - | - | returns: list[QOp] (noisy operations) - v -inner.execute(noisy_ops) - | - | yields: list[QOp] - v -qsim.run(noisy_qops) - | - | returns: list[dict] e.g. [{("m", 0): 1, ("m", 1): 0}] - v -inner.receive_results(temp_meas) --> stores via assign_int - | -inner.result_bits(measurements) --> extracts bits, filters __private__ vars - | - | returns: dict[(str, int), int] - v -outer.receive_results([transmit_meas]) --> stores via assign_int - | -outer.results(return_int=...) - | - | returns: dict[str, int_or_bitstring] -``` - -## What `execute()` Yields - -`execute()` is a generator/iterator. It yields `list[QOp | MOp]`. - -Behavior: -- Walks the op list, recursively flattening SeqBlock and evaluating IfBlock conditions -- Buffers QOps and MOps -- Executes COps inline (never yielded) -- Yields the buffer when a measurement QOp is encountered (name in {"measure Z", "Measure", "Measure +Z"}) -- Yields remaining buffer at end of program -- Classical ops (assignment, Result mapping, FFCall) are handled during the walk - -### QOp Fields (what consumers read) - -``` -name: str # e.g. "H", "Measure", "RZ" -sim_name: str # resolved name for simulator -args: list[int] | list[tuple] # qubit IDs -returns: list | None # measurement targets, e.g. [["m", 0], ["m", 1]] -metadata: dict | None # includes "angle", "angles", "var_output" -angles: tuple[float, ...] | None # rotation angles in radians -``` - -Fields read by QuantumSimulator: `sim_name`, `args`, `metadata`, `returns` -Fields read by GenericOpProc: only `isinstance()` checks (QOp vs MOp routing) - -### MOp Fields - -``` -name: str -args: list | None -returns: list | None -metadata: dict | None # may contain "duration" -``` - -## The Generator Problem - -Python `execute()` is a coroutine -- yields batches, caller runs quantum sim, feeds -measurements back via `receive_results()`, then execution resumes. Conditional branches -may depend on those measurement results. - -**Solution: PyO3 iterator class.** A `#[pyclass]` that holds interpreter state and -advances to the next yield point on each `__next__()`. The Rust struct holds program -state, and each `__next__` call processes ops until the next measurement batch. - -## Dual Interpreter Pattern - -HybridEngine uses TWO interpreter instances: - -**Outer interpreter:** -- Drives the full program -- Has only program-declared variables -- Receives filtered measurement bits from inner via `receive_results()` - -**Inner interpreter:** -- Processes noisy ops from error model -- Gets extra `__q{i}__` private vars via `add_cvar()` (one per qubit, i64, size 1) -- `result_bits()` filters out `__`-prefixed vars when transmitting back - -Both use the same code, same class. The inner just handles a flat list of QOps -(no blocks to flatten) and has extra private vars. - -## Method Details - -### `init(program, foreign_obj) -> int` - -1. Parse program: JSON string -> dict, or accept dict directly -2. Validate format ("PHIR/JSON" or "PHIR") and version (< 0.2.0) -3. Optionally validate against PHIR schema (if `phir_validate` is True) -4. Build internal AST / operation list -5. Extract variable definitions, initialize environment (all vars to 0) -6. Check foreign function calls against foreign object -7. Return num_qubits - -### `shot_reinit()` - -Reset all variable values to 0. Keep variable definitions. - -### `execute(sequence) -> Iterator[list[QOp | MOp]]` - -Walk ops, flatten blocks, execute classical ops, yield quantum op batches. -See "What execute() Yields" above. - -### `receive_results(qsim_results: list[dict])` - -Each dict maps `cvar` or `(cvar, idx)` to a value. -For each key/value, calls `assign_int(key, value)`. - -### `result_bits(bits, filter_private=True) -> dict` - -`bits` is a list of measurement dicts from qsim.run(). -Iterates all (cvar, bit_idx) pairs, filters out `__`-prefixed vars, -returns `{(cvar, bit_idx): self.get_bit(cvar, bit_idx)}`. - -Important: reads from own env (after receive_results), not from input. - -### `results(return_int=True) -> dict` - -Returns ALL variables in csym2id. -- return_int=True: values are integers -- return_int=False: values are zero-padded binary strings ("{:0{width}b}") - -### `add_cvar(cvar, dtype, size)` - -Dynamically add a new classical variable after init. Used by HybridEngine -for the inner interpreter's private qubit vars. - -### `assign_int(cvar, val)` - -Assign integer value to variable or specific bit. -- `cvar` is a string: assign whole variable -- `cvar` is (string, int): assign to bit at index - -## Name Resolver - -`sim_name_resolver(qop)` translates PHIR gate names to simulator names: -- `RZZ(0.0)` -> `"I"` -- `RZZ(pi/2)` -> `"SZZ"` -- `RZZ(3pi/2)` -> `"SZZdg"` -- `RZ(angle)` -> tries clifford match -- `R1XY(angles)` -> tries clifford match -- Otherwise returns `qop.name` - -Applied during PHIR parsing when building QOp objects. The Rust side needs this -for yielded QOps to have correct `sim_name` values. - -## Foreign Function Calls - -FFCalls are COps handled during `execute()` -- never yielded. The foreign object -is a Python object implementing `ForeignObjectProtocol`: - - def exec(func_name: str, args: Sequence) -> tuple | int - -The Rust side must call back into this Python object for FFCalls. This requires -holding a `Py` reference. - -## Edge Cases - -- **Empty programs**: `execute([])` yields nothing. `results()` returns `{}` -- **No measurements**: buffer yielded at end (if non-empty). No receive_results() calls. -- **Only classical ops**: all handled inline. Nothing yielded. results() has computed values. -- **"Result" cop**: maps internal register to external name, copies value, creates dest var if needed. - -## What Exists vs What Needs Building - -### Reuse from `pecos-phir-json/src/v0_1/`: - -| Component | File | Notes | -|-----------|------|-------| -| PHIR JSON parsing | `ast.rs` | Complete | -| Variable storage | `environment.rs` | Complete -- DataType, TypedValue, Environment | -| Expression eval | `expression.rs` | Complete -- all operators | -| Classical ops | `operations.rs` | Adapt -- different interface needed | -| Block flattening | `block_iterative_executor.rs` | Adapt -- yield pattern differs | - -### New code needed: - -| Component | Location | Description | -|-----------|----------|-------------| -| Rust interpreter struct | `pecos-phir-json` | State machine wrapping existing internals | -| PyO3 wrapper class | `pecos-rslib` | `#[pyclass]` with protocol methods | -| PyO3 iterator | `pecos-rslib` | `__iter__`/`__next__` for execute() generator | -| QOp/MOp pyclass | `pecos-rslib` | Lightweight attribute bags for yielded ops | -| Name resolver | `pecos-phir-json` | Port of sim_name_resolver | -| result_bits() | `pecos-phir-json` | Bit extraction with private var filtering | -| receive_results() | `pecos-phir-json` | Handle list[dict] format | -| results() | `pecos-phir-json` | Return dict with return_int flag | - -## Validation Strategy - -The Rust interpreter must produce identical results to the Python one. Test by: -1. Running existing PHIR test programs through both interpreters -2. Comparing shot-by-shot results -3. Testing edge cases (empty programs, no measurements, only classical ops) -4. Testing the dual-interpreter pattern (outer + inner with private vars) From ebe26bdc6cfb90999dc89bb09fbd8252a12d550c Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Fri, 8 May 2026 10:45:16 -0600 Subject: [PATCH 050/125] Fault tolerance infrastructure: meas_sampling, fault catalog, decoders, Clifford gates, tracked operators Raw measurement DEM sampling (meas_sampling): - Stochastic fault table overlay: ideal measurements XOR independent physical faults - Geometric skip sampling for O(fired) performance per mechanism - Columnar bit-packed storage with lazy row extraction - SymbolicSparseStab PZ (reset) for correct cross-reset correlations - All sim_neo backends return unified RawMeasurementResult Fault catalog and targeted lookup decoder: - Per-location, per-alternative fault lookup with PauliString labels - Independent-mechanism probability model with lazy k-fault configuration iterators - Targeted ML decoder: exact truncated search for k=0,1,2,3+ - Brute-force-verified correctness against full enumeration Full Clifford gate support: - SX, SXdg, SY, SYdg, SXX, SXXdg, SYY, SYYdg, SZZ, SZZdg, SWAP, F, Fdg - Across fault_sampler, symbolic_measurement_history, propagate_forward, build_fault_table, build_fault_catalog, sim_neo bindings, pecos-neo runner - CliffordMatrixOracle for brute-force U*P*U-dagger gate verification - CY sign fix in symbolic_sparse_stab_bitset - SZdg/SXdg/SYdg propagation fix in pauli_prop_checker Tracked operators vs observables: - Separate ID spaces: observables keep L (Stim-compatible), tracked operators get pecos_tracked_op extension lines - GPU influence sampler filters tracked ops from logical error counts - merge_dem_outputs_from() replaces fragile field-by-field copy - DemOutput predicates made mutually exclusive DEM sampling backend: - dem_sampling() sim_neo backend with auto/stochastic/coherent method selection Test coverage: - 368 fault_tolerance Rust tests, 90+ Python tests - Geometric sampling firing rate validation - Configuration probability sum = 1.0 invariant - Columnar word-boundary masking at 63/64/65 shots - PZ absorbs all Pauli components (X, Y, Z) - Cross-reset independence in symbolic_measurement_history - Targeted decoder with unexplainable syndromes - Observable flip rate comparison (meas_sampling vs stabilizer) - Oracle-verified Clifford gate conjugation tables - Zero-noise cross-validation across backends --- .github/workflows/python-test.yml | 12 + .github/workflows/selene-plugins.yml | 10 +- .typos.toml | 2 + Cargo.lock | 654 +- Cargo.toml | 20 +- Justfile | 25 +- crates/benchmarks/Cargo.toml | 4 + crates/benchmarks/benches/benchmarks.rs | 16 +- .../benchmarks/benches/modules/dem_builder.rs | 165 + .../benchmarks/benches/modules/dem_sampler.rs | 334 +- .../benches/modules/gpu_influence_sampler.rs | 49 +- .../benchmarks/benches/modules/quizx_eval.rs | 2 +- .../benches/modules/stab_mps_vs_stab_vec.rs | 404 + .../modules/{clifford_rz.rs => stab_vec.rs} | 52 +- 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python/quantum-pecos/tests/docs/rust_crate/tests/development_foreign_plugins.rs rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/__init__.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/analysis/__init__.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/analysis/test_connectivity_analyzer.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/analysis/test_depth_analyzer.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/analysis/test_parallelism_analyzer.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/analysis/test_qubit_state_validator.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/analysis/test_resource_counter.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/analysis/test_t_count_analyzer.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/optimizations/__init__.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/optimizations/test_gate_cancellation.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/optimizations/test_identity_removal.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/optimizations/test_inverse_cancellation.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/optimizations/test_pipeline.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/optimizations/test_rotation_merging.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_codegen_guppy.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_codegen_qasm.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_codegen_qir.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_codegen_quantum_circuit.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_codegen_stim.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_compare.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_converter.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_integration.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_nodes.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_permute.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_pretty_print.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_roundtrip.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_serialize.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_ast_visitor.py (100%) rename python/quantum-pecos/tests/pecos/slr/{ast => ast_tests}/test_codegen_equivalence.py (100%) rename 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python/quantum-pecos/tests/pecos/test_selene_sim_parity.py create mode 100644 python/quantum-pecos/tests/pecos/unit/test_surface_sweep_math.py create mode 100644 python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py create mode 100644 python/quantum-pecos/tests/qec/surface/test_surface_geometry.py create mode 100644 python/quantum-pecos/tests/qec/surface/test_surface_metadata.py create mode 100644 python/quantum-pecos/tests/qec/test_analysis_meas_sampling.py create mode 100644 python/quantum-pecos/tests/qec/test_decomposed_dem_invariants.py create mode 100644 python/quantum-pecos/tests/qec/test_dem_sampler_modes.py create mode 100644 python/quantum-pecos/tests/qec/test_fault_catalog.py create mode 100644 python/quantum-pecos/tests/qec/test_meas_sampling_backend.py create mode 100644 python/quantum-pecos/tests/qec/test_meas_sampling_generality.py create mode 100644 python/quantum-pecos/tests/qec/test_raw_measurement_result.py create mode 100644 python/quantum-pecos/tests/qec/test_sample_batch.py create mode 100644 python/quantum-pecos/tests/qec/test_traced_qis_clifford_pipeline.py create mode 100644 python/quantum-pecos/tests/qec/test_traced_qis_slow_integration.py create mode 100644 python/selene-plugins/pecos-selene-mast/Cargo.toml create mode 100644 python/selene-plugins/pecos-selene-mast/README.md rename python/selene-plugins/{pecos-selene-clifford-rz => pecos-selene-mast}/hatch_build.py (93%) create mode 100644 python/selene-plugins/pecos-selene-mast/pyproject.toml rename python/selene-plugins/{pecos-selene-clifford-rz/python/pecos_selene_clifford_rz => pecos-selene-mast/python/pecos_selene_mast}/__init__.py (81%) create mode 100644 python/selene-plugins/pecos-selene-mast/python/pecos_selene_mast/plugin.py create mode 100644 python/selene-plugins/pecos-selene-mast/src/lib.rs create mode 100644 python/selene-plugins/pecos-selene-stab-mps/Cargo.toml create mode 100644 python/selene-plugins/pecos-selene-stab-mps/README.md create mode 100644 python/selene-plugins/pecos-selene-stab-mps/hatch_build.py create mode 100644 python/selene-plugins/pecos-selene-stab-mps/pyproject.toml create mode 100644 python/selene-plugins/pecos-selene-stab-mps/python/pecos_selene_stab_mps/__init__.py create mode 100644 python/selene-plugins/pecos-selene-stab-mps/python/pecos_selene_stab_mps/plugin.py create mode 100644 python/selene-plugins/pecos-selene-stab-mps/src/lib.rs rename python/selene-plugins/{pecos-selene-clifford-rz => pecos-selene-stab-vec}/Cargo.toml (80%) rename python/selene-plugins/{pecos-selene-clifford-rz => pecos-selene-stab-vec}/README.md (62%) create mode 100644 python/selene-plugins/pecos-selene-stab-vec/hatch_build.py rename python/selene-plugins/{pecos-selene-clifford-rz => pecos-selene-stab-vec}/pyproject.toml (76%) create mode 100644 python/selene-plugins/pecos-selene-stab-vec/python/pecos_selene_stab_vec/__init__.py rename python/selene-plugins/{pecos-selene-clifford-rz/python/pecos_selene_clifford_rz => pecos-selene-stab-vec/python/pecos_selene_stab_vec}/plugin.py (83%) rename python/selene-plugins/{pecos-selene-clifford-rz => pecos-selene-stab-vec}/src/lib.rs (86%) rename python/selene-plugins/{pecos-selene-clifford-rz/tests/test_clifford_rz.py => pecos-selene-stab-vec/tests/test_stab_vec.py} (86%) create mode 100644 scripts/bench_raw_meas_sampling.py create mode 100644 scripts/compare_meas_sampling_pipeline.py diff --git a/.github/workflows/python-test.yml b/.github/workflows/python-test.yml index 891b9fad0..e347ddcda 100644 --- a/.github/workflows/python-test.yml +++ b/.github/workflows/python-test.yml @@ -218,5 +218,17 @@ jobs: - name: Run Python tests run: just pytest + - name: Run slow Python tests + # Only run on the primary Linux/newest-Python cell to keep the full + # matrix fast. Dropping this entirely would let the `slow` lane + # silently atrophy, which is exactly what the `slow` marker is + # supposed to prevent. + # + # The `3.14` literal below must track the newest entry of the + # `python-version` matrix at the top of this file (line ~34). Bump + # both together. + if: runner.os == 'Linux' && matrix.python-version == '3.14' + run: just pytest-slow + - name: Run linting run: just lint check diff --git a/.github/workflows/selene-plugins.yml b/.github/workflows/selene-plugins.yml index 790a04d1b..8efabd9e1 100644 --- a/.github/workflows/selene-plugins.yml +++ b/.github/workflows/selene-plugins.yml @@ -11,6 +11,7 @@ on: - 'python/selene-plugins/**' - 'crates/pecos-simulators/**' - 'crates/pecos-core/**' + - 'exp/pecos-stab-tn/**' - '.github/workflows/selene-plugins.yml' pull_request: branches: [master, development, dev] @@ -18,6 +19,7 @@ on: - 'python/selene-plugins/**' - 'crates/pecos-simulators/**' - 'crates/pecos-core/**' + - 'exp/pecos-stab-tn/**' - '.github/workflows/selene-plugins.yml' workflow_dispatch: @@ -120,8 +122,12 @@ jobs: package: pecos_selene_stabilizer - name: pecos-selene-statevec package: pecos_selene_statevec - - name: pecos-selene-clifford-rz - package: pecos_selene_clifford_rz + - name: pecos-selene-stab-vec + package: pecos_selene_stab_vec + - name: pecos-selene-stab-mps + package: pecos_selene_stab_mps + - name: pecos-selene-mast + package: pecos_selene_mast steps: - uses: actions/checkout@v6 diff --git a/.typos.toml b/.typos.toml index 05b3f16f9..716e3bb44 100644 --- a/.typos.toml +++ b/.typos.toml @@ -40,3 +40,5 @@ egative = "egative" agger = "agger" # Ruff rule code prefix (flake8-copyright) CPY = "CPY" +# Abbreviation for "undetectable" in fault enumeration debug output +UNDET = "UNDET" diff --git a/Cargo.lock b/Cargo.lock index 2b4094e7e..f1794bcbc 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -85,6 +85,15 @@ version = "0.1.6" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "4b46cbb362ab8752921c97e041f5e366ee6297bd428a31275b9fcf1e380f7299" +[[package]] +name = "ansi_term" +version = "0.12.1" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "d52a9bb7ec0cf484c551830a7ce27bd20d67eac647e1befb56b0be4ee39a55d2" +dependencies = [ + "winapi", +] + [[package]] name = "anstream" version = "1.0.0" @@ -254,9 +263,9 @@ dependencies = [ [[package]] name = "assert_cmd" -version = "2.2.0" +version = "2.2.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "9a686bbee5efb88a82df0621b236e74d925f470e5445d3220a5648b892ec99c9" +checksum = "39bae1d3fa576f7c6519514180a72559268dd7d1fe104070956cb687bc6673bd" dependencies = [ "anstyle", "bstr", @@ -284,6 +293,17 @@ version = "1.1.2" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "1505bd5d3d116872e7271a6d4e16d81d0c8570876c8de68093a09ac269d8aac0" +[[package]] +name = "atty" +version = "0.2.14" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "d9b39be18770d11421cdb1b9947a45dd3f37e93092cbf377614828a319d5fee8" +dependencies = [ + "hermit-abi 0.1.19", + "libc", + "winapi", +] + [[package]] name = "autocfg" version = "1.5.0" @@ -292,9 +312,9 @@ checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8" [[package]] name = "aws-lc-rs" -version = "1.16.2" +version = "1.16.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "a054912289d18629dc78375ba2c3726a3afe3ff71b4edba9dedfca0e3446d1fc" +checksum = "0ec6fb3fe69024a75fa7e1bfb48aa6cf59706a101658ea01bfd33b2b248a038f" dependencies = [ "aws-lc-sys", "zeroize", @@ -302,9 +322,9 @@ dependencies = [ [[package]] name = "aws-lc-sys" -version = "0.39.1" +version = "0.40.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "83a25cf98105baa966497416dbd42565ce3a8cf8dbfd59803ec9ad46f3126399" +checksum = "f50037ee5e1e41e7b8f9d161680a725bd1626cb6f8c7e901f91f942850852fe7" dependencies = [ "cc", "cmake", @@ -336,6 +356,7 @@ version = "0.2.0-dev.0" dependencies = [ "criterion", "cxx", + "nalgebra", "num", "num-complex 0.4.6", "pecos", @@ -349,6 +370,7 @@ dependencies = [ "pecos-quantum", "pecos-random", "pecos-simulators", + "pecos-stab-tn", "quizx", "rand 0.10.1", "rand_xoshiro 0.8.0", @@ -362,7 +384,7 @@ version = "0.72.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "993776b509cfb49c750f11b8f07a46fa23e0a1386ffc01fb1e7d343efc387895" dependencies = [ - "bitflags", + "bitflags 2.11.1", "cexpr", "clang-sys", "itertools 0.13.0", @@ -438,9 +460,15 @@ checksum = "b71798fca2c1fe1086445a7258a4bc81e6e49dcd24c8d0dd9a1e57395b603f51" [[package]] name = "bitflags" -version = "2.11.0" +version = "1.3.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "843867be96c8daad0d758b57df9392b6d8d271134fce549de6ce169ff98a92af" +checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a" + +[[package]] +name = "bitflags" +version = "2.11.1" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "c4512299f36f043ab09a583e57bceb5a5aab7a73db1805848e8fef3c9e8c78b3" dependencies = [ "serde_core", ] @@ -501,6 +529,15 @@ version = "0.1.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "38c99613cb3cd7429889a08dfcf651721ca971c86afa30798461f8eee994de47" +[[package]] +name = "bp" +version = "0.1.0" +source = "git+https://github.com/yuewuo/mwpf?tag=v0.2.12#b8444428f999457208c4b0956f3f1c745a0ec2d5" +dependencies = [ + "float-cmp", + "rand 0.8.6", +] + [[package]] name = "bstr" version = "1.12.1" @@ -668,7 +705,7 @@ checksum = "6f8d983286843e49675a4b7a2d174efe136dc93a18d69130dd18198a6c167601" dependencies = [ "cfg-if", "cpufeatures 0.3.0", - "rand_core 0.10.0", + "rand_core 0.10.1", ] [[package]] @@ -725,9 +762,24 @@ dependencies = [ [[package]] name = "clap" -version = "4.6.0" +version = "2.34.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "a0610544180c38b88101fecf2dd634b174a62eef6946f84dfc6a7127512b381c" +dependencies = [ + "ansi_term", + "atty", + "bitflags 1.3.2", + "strsim 0.8.0", + "textwrap", + "unicode-width 0.1.14", + "vec_map", +] + +[[package]] +name = "clap" +version = "4.6.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b193af5b67834b676abd72466a96c1024e6a6ad978a1f484bd90b85c94041351" +checksum = "1ddb117e43bbf7dacf0a4190fef4d345b9bad68dfc649cb349e7d17d28428e51" dependencies = [ "clap_builder", "clap_derive", @@ -742,23 +794,23 @@ dependencies = [ "anstream", "anstyle", "clap_lex", - "strsim", + "strsim 0.11.1", ] [[package]] name = "clap_complete" -version = "4.6.1" +version = "4.6.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "406e68b4de5c59cfb8f750a7cbd4d31ae153788b8352167c1e5f4fc26e8c91e9" +checksum = "3ff7a1dccbdd8b078c2bdebff47e404615151534d5043da397ec50286816f9cb" dependencies = [ - "clap", + "clap 4.6.1", ] [[package]] name = "clap_derive" -version = "4.6.0" +version = "4.6.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "1110bd8a634a1ab8cb04345d8d878267d57c3cf1b38d91b71af6686408bbca6a" +checksum = "f2ce8604710f6733aa641a2b3731eaa1e8b3d9973d5e3565da11800813f997a9" dependencies = [ "heck 0.5.0", "proc-macro2", @@ -798,7 +850,7 @@ checksum = "af491d569909a7e4dee0ad7db7f5341fef5c614d5b8ec8cf765732aba3cff681" dependencies = [ "serde", "termcolor", - "unicode-width", + "unicode-width 0.2.2", ] [[package]] @@ -825,7 +877,7 @@ checksum = "d64e8af5551369d19cf50138de61f1c42074ab970f74e99be916646777f8fc87" dependencies = [ "encode_unicode", "libc", - "unicode-width", + "unicode-width 0.2.2", "windows-sys 0.61.2", ] @@ -1071,7 +1123,7 @@ dependencies = [ "anes", "cast", "ciborium", - "clap", + "clap 4.6.1", "criterion-plot", "itertools 0.13.0", "num-traits", @@ -1176,6 +1228,12 @@ dependencies = [ "memchr", ] +[[package]] +name = "cute" +version = "0.3.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "45e700c2d1c3feea9b695e79b2dfeeb93040556a58c556fae23f71b1e6b449fd" + [[package]] name = "cxx" version = "1.0.194" @@ -1212,7 +1270,7 @@ version = "1.0.194" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "d0956799fa8678d4c50eed028f2de1c0552ae183c76e976cf7ca8c4e36a7c328" dependencies = [ - "clap", + "clap 4.6.1", "codespan-reporting", "indexmap 2.14.0", "proc-macro2", @@ -1257,7 +1315,7 @@ dependencies = [ "ident_case", "proc-macro2", "quote", - "strsim", + "strsim 0.11.1", "syn 2.0.117", ] @@ -1489,7 +1547,7 @@ version = "0.3.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "1e0e367e4e7da84520dedcac1901e4da967309406d1e51017ae1abfb97adbd38" dependencies = [ - "bitflags", + "bitflags 2.11.1", "objc2", ] @@ -1716,6 +1774,15 @@ dependencies = [ "miniz_oxide", ] +[[package]] +name = "float-cmp" +version = "0.10.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "b09cf3155332e944990140d967ff5eceb70df778b34f77d8075db46e4704e6d8" +dependencies = [ + "num-traits", +] + [[package]] name = "fnv" version = "1.0.7" @@ -1764,7 +1831,7 @@ dependencies = [ "cc", "cfg-if", "chrono", - "clap", + "clap 4.6.1", "core_affinity", "derivative", "lazy_static", @@ -1774,7 +1841,7 @@ dependencies = [ "pbr", "petgraph 0.6.5", "priority-queue 1.4.0", - "rand 0.8.5", + "rand 0.8.6", "rand_xoshiro 0.6.0", "rayon", "serde", @@ -1932,16 +1999,16 @@ dependencies = [ "cfg-if", "libc", "r-efi 6.0.0", - "rand_core 0.10.0", + "rand_core 0.10.1", "wasip2", "wasip3", ] [[package]] name = "gimli" -version = "0.33.1" +version = "0.33.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "19e16c5073773ccf057c282be832a59ee53ef5ff98db3aeff7f8314f52ffc196" +checksum = "0bf7f043f89559805f8c7cacc432749b2fa0d0a0a9ee46ce47164ed5ba7f126c" dependencies = [ "fnv", "hashbrown 0.16.1", @@ -2115,7 +2182,7 @@ version = "0.3.2" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "b89c83349105e3732062a895becfc71a8f921bb71ecbbdd8ff99263e3b53a0ca" dependencies = [ - "bitflags", + "bitflags 2.11.1", "gpu-descriptor-types", "hashbrown 0.15.5", ] @@ -2126,7 +2193,7 @@ version = "0.2.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "fdf242682df893b86f33a73828fb09ca4b2d3bb6cc95249707fc684d27484b91" dependencies = [ - "bitflags", + "bitflags 2.11.1", ] [[package]] @@ -2189,6 +2256,20 @@ version = "0.17.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "4f467dd6dccf739c208452f8014c75c18bb8301b050ad1cfb27153803edb0f51" +[[package]] +name = "heapz" +version = "1.1.4" +source = "git+https://github.com/yuewuo/mwpf?tag=v0.2.12#b8444428f999457208c4b0956f3f1c745a0ec2d5" + +[[package]] +name = "heck" +version = "0.3.3" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "6d621efb26863f0e9924c6ac577e8275e5e6b77455db64ffa6c65c904e9e132c" +dependencies = [ + "unicode-segmentation", +] + [[package]] name = "heck" version = "0.4.1" @@ -2201,6 +2282,15 @@ version = "0.5.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "2304e00983f87ffb38b55b444b5e3b60a884b5d30c0fca7d82fe33449bbe55ea" +[[package]] +name = "hermit-abi" +version = "0.1.19" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "62b467343b94ba476dcb2500d242dadbb39557df889310ac77c5d99100aaac33" +dependencies = [ + "libc", +] + [[package]] name = "hermit-abi" version = "0.5.2" @@ -2219,6 +2309,25 @@ version = "0.2.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "dfa686283ad6dd069f105e5ab091b04c62850d3e4cf5d67debad1933f55023df" +[[package]] +name = "highs" +version = "1.6.1" +source = "git+https://github.com/yuewuo/mwpf?tag=v0.2.12#b8444428f999457208c4b0956f3f1c745a0ec2d5" +dependencies = [ + "highs-sys", + "log", +] + +[[package]] +name = "highs-sys" +version = "1.14.2" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "11a9fa9dea5b5f277075460b695db30ad7e5ce28554f2dd27c312c640acd101f" +dependencies = [ + "bindgen", + "cmake", +] + [[package]] name = "html-escape" version = "0.2.13" @@ -2409,9 +2518,9 @@ dependencies = [ [[package]] name = "hyper-rustls" -version = "0.27.8" +version = "0.27.9" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "c2b52f86d1d4bc0d6b4e6826d960b1b333217e07d36b882dca570a5e1c48895b" +checksum = "33ca68d021ef39cf6463ab54c1d0f5daf03377b70561305bb89a8f83aab66e0f" dependencies = [ "http", "hyper", @@ -2617,7 +2726,7 @@ dependencies = [ "console", "portable-atomic", "rayon", - "unicode-width", + "unicode-width 0.2.2", "unit-prefix", "web-time", ] @@ -2698,7 +2807,7 @@ version = "0.4.17" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "3640c1c38b8e4e43584d8df18be5fc6b0aa314ce6ebf51b53313d4306cca8e46" dependencies = [ - "hermit-abi", + "hermit-abi 0.5.2", "libc", "windows-sys 0.61.2", ] @@ -2906,15 +3015,15 @@ dependencies = [ [[package]] name = "libbz2-rs-sys" -version = "0.2.2" +version = "0.2.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "2c4a545a15244c7d945065b5d392b2d2d7f21526fba56ce51467b06ed445e8f7" +checksum = "b3a6a8c165077efc8f3a971534c50ea6a1a18b329ef4a66e897a7e3a1494565f" [[package]] name = "libc" -version = "0.2.184" +version = "0.2.185" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "48f5d2a454e16a5ea0f4ced81bd44e4cfc7bd3a507b61887c99fd3538b28e4af" +checksum = "52ff2c0fe9bc6cb6b14a0592c2ff4fa9ceb83eea9db979b0487cd054946a2b8f" [[package]] name = "libloading" @@ -2948,7 +3057,7 @@ version = "0.1.16" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "e02f3bb43d335493c96bf3fd3a321600bf6bd07ed34bc64118e9293bdffea46c" dependencies = [ - "bitflags", + "bitflags 2.11.1", "libc", "plain", "redox_syscall 0.7.4", @@ -2994,6 +3103,12 @@ dependencies = [ "semver", ] +[[package]] +name = "lnexp" +version = "0.2.1" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "f98924c778103b33dcf6beb1af911977e5d65c6cae74b45e133b3c90bd6db948" + [[package]] name = "lock_api" version = "0.4.14" @@ -3067,6 +3182,12 @@ dependencies = [ "libc", ] +[[package]] +name = "maplit" +version = "1.0.2" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "3e2e65a1a2e43cfcb47a895c4c8b10d1f4a61097f9f254f183aee60cad9c651d" + [[package]] name = "matrixmultiply" version = "0.3.10" @@ -3092,6 +3213,12 @@ dependencies = [ "rustix", ] +[[package]] +name = "min_max_macros" +version = "0.1.1" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "131a74fe105e2662ce9646e3a3af4c0eeb19bc0e5936852bf81341bfc415b9f2" + [[package]] name = "minimal-lexical" version = "0.2.1" @@ -3119,6 +3246,54 @@ dependencies = [ "windows-sys 0.61.2", ] +[[package]] +name = "more-asserts" +version = "0.3.1" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "1fafa6961cabd9c63bcd77a45d7e3b7f3b552b70417831fb0f56db717e72407e" + +[[package]] +name = "mwpf" +version = "0.2.12" +source = "git+https://github.com/yuewuo/mwpf?tag=v0.2.12#b8444428f999457208c4b0956f3f1c745a0ec2d5" +dependencies = [ + "base64", + "bp", + "cfg-if", + "chrono", + "ciborium", + "clap 4.6.1", + "derivative", + "flate2", + "getrandom 0.2.17", + "hashbrown 0.15.5", + "heapz", + "highs", + "itertools 0.14.0", + "lazy_static", + "lnexp", + "maplit", + "more-asserts", + "num-bigint", + "num-rational", + "num-traits", + "parking_lot", + "pheap", + "prettytable-rs", + "priority-queue 2.7.0", + "rand 0.8.6", + "rand_xoshiro 0.6.0", + "serde", + "serde-wasm-bindgen", + "serde_json", + "serde_variant", + "slp", + "sugar", + "tempfile", + "thread-priority", + "urlencoding", +] + [[package]] name = "naga" version = "29.0.1" @@ -3127,7 +3302,7 @@ checksum = "aa2630921705b9b01dcdd0b6864b9562ca3c1951eecd0f0c4f5f04f61e412647" dependencies = [ "arrayvec 0.7.6", "bit-set 0.9.1", - "bitflags", + "bitflags 2.11.1", "cfg-if", "cfg_aliases", "codespan-reporting", @@ -3362,6 +3537,7 @@ dependencies = [ "num-bigint", "num-integer", "num-traits", + "serde", ] [[package]] @@ -3380,7 +3556,7 @@ version = "1.17.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "91df4bbde75afed763b708b7eee1e8e7651e02d97f6d5dd763e89367e957b23b" dependencies = [ - "hermit-abi", + "hermit-abi 0.5.2", "libc", ] @@ -3399,7 +3575,7 @@ version = "0.3.2" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "2a180dd8642fa45cdb7dd721cd4c11b1cadd4929ce112ebd8b9f5803cc79d536" dependencies = [ - "bitflags", + "bitflags 2.11.1", "dispatch2", "objc2", ] @@ -3416,7 +3592,7 @@ version = "0.3.2" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "e3e0adef53c21f888deb4fa59fc59f7eb17404926ee8a6f59f5df0fd7f9f3272" dependencies = [ - "bitflags", + "bitflags 2.11.1", "objc2", "objc2-core-foundation", ] @@ -3427,7 +3603,7 @@ version = "0.3.2" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "a0125f776a10d00af4152d74616409f0d4a2053a6f57fa5b7d6aa2854ac04794" dependencies = [ - "bitflags", + "bitflags 2.11.1", "block2", "objc2", "objc2-foundation", @@ -3439,7 +3615,7 @@ version = "0.3.2" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "96c1358452b371bf9f104e21ec536d37a650eb10f7ee379fff67d2e08d537f1f" dependencies = [ - "bitflags", + "bitflags 2.11.1", "objc2", "objc2-core-foundation", "objc2-foundation", @@ -3510,7 +3686,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "b7d950ca161dc355eaf28f82b11345ed76c6e1f6eb1f4f4479e0323b9e2fbd0e" dependencies = [ "num-traits", - "rand 0.8.5", + "rand 0.8.6", "serde", ] @@ -3654,6 +3830,7 @@ dependencies = [ "ndarray 0.17.2", "pecos-build", "pecos-decoder-core", + "pecos-pymatching", "thiserror 2.0.18", ] @@ -3662,7 +3839,7 @@ name = "pecos-cli" version = "0.2.0-dev.0" dependencies = [ "assert_cmd", - "clap", + "clap 4.6.1", "clap_complete", "env_logger", "log", @@ -3683,7 +3860,7 @@ dependencies = [ "num-traits", "pecos-random", "rand 0.10.1", - "rand_core 0.10.0", + "rand_core 0.10.1", "rand_xoshiro 0.8.0", "serde", "serde_json", @@ -3736,6 +3913,8 @@ version = "0.2.0-dev.0" dependencies = [ "anyhow", "ndarray 0.17.2", + "pecos-random", + "rayon", "thiserror 2.0.18", ] @@ -3747,16 +3926,33 @@ dependencies = [ "pecos-decoder-core", "pecos-fusion-blossom", "pecos-ldpc-decoders", + "pecos-mwpf", "pecos-pymatching", "pecos-relay-bp", "pecos-tesseract", + "pecos-uf-decoder", +] + +[[package]] +name = "pecos-eeg" +version = "0.2.0-dev.0" +dependencies = [ + "pecos-core", + "pecos-qec", + "pecos-quantum", + "pecos-random", + "pecos-simulators", + "rayon", + "serde_json", + "smallvec", + "thiserror 2.0.18", ] [[package]] name = "pecos-engines" version = "0.2.0-dev.0" dependencies = [ - "bitflags", + "bitflags 2.11.1", "bitvec", "bytemuck", "dyn-clone", @@ -3813,6 +4009,7 @@ dependencies = [ "fusion-blossom", "ndarray 0.17.2", "pecos-decoder-core", + "serde_json", "thiserror 2.0.18", ] @@ -3840,7 +4037,7 @@ dependencies = [ "pecos-simulators", "pollster", "rand 0.10.1", - "rand_core 0.10.0", + "rand_core 0.10.1", "serde_json", "wgpu", ] @@ -3910,11 +4107,23 @@ dependencies = [ "pecos-core", ] +[[package]] +name = "pecos-mwpf" +version = "0.2.0-dev.0" +dependencies = [ + "mwpf", + "ndarray 0.17.2", + "pecos-decoder-core", + "serde_json", + "thiserror 2.0.18", +] + [[package]] name = "pecos-neo" version = "0.2.0-dev.0" dependencies = [ "criterion", + "num-complex 0.4.6", "num_cpus", "pecos-core", "pecos-engines", @@ -3927,7 +4136,7 @@ dependencies = [ "pecos-simulators", "proptest", "rand 0.10.1", - "rand_core 0.10.0", + "rand_core 0.10.1", "rayon", "smallvec", "thiserror 2.0.18", @@ -4036,12 +4245,14 @@ dependencies = [ "ndarray 0.17.2", "pecos-core", "pecos-decoder-core", + "pecos-num", "pecos-quantum", "pecos-random", "pecos-simulators", "rand 0.10.1", - "rand_core 0.10.0", + "rand_core 0.10.1", "rayon", + "serde_json", "smallvec", "thiserror 2.0.18", "wide 1.3.0", @@ -4069,6 +4280,7 @@ dependencies = [ "rand 0.10.1", "selene-simple-runtime", "selene-soft-rz-runtime", + "serde", "serde_json", "tempfile", ] @@ -4109,7 +4321,7 @@ name = "pecos-random" version = "0.2.0-dev.0" dependencies = [ "rand 0.10.1", - "rand_core 0.10.0", + "rand_core 0.10.1", "rand_xoshiro 0.8.0", "random_tester", "rapidhash", @@ -4161,6 +4373,7 @@ dependencies = [ "pecos-wasm", "pyo3", "rand 0.10.1", + "rayon", "serde_json", "tempfile", ] @@ -4178,6 +4391,26 @@ dependencies = [ "pyo3", ] +[[package]] +name = "pecos-rslib-exp" +version = "0.2.0-dev.0" +dependencies = [ + "num-complex 0.4.6", + "pecos-core", + "pecos-eeg", + "pecos-neo", + "pecos-qec", + "pecos-quantum", + "pecos-random", + "pecos-simulators", + "pecos-stab-tn", + "pyo3", + "rayon", + "serde", + "serde_json", + "smallvec", +] + [[package]] name = "pecos-rslib-llvm" version = "0.2.0-dev.0" @@ -4191,21 +4424,43 @@ dependencies = [ ] [[package]] -name = "pecos-selene-clifford-rz" +name = "pecos-selene-core" version = "0.2.0-dev.0" dependencies = [ "anyhow", + "clap 4.6.1", "pecos-core", "pecos-simulators", "selene-core 0.2.1", ] [[package]] -name = "pecos-selene-core" +name = "pecos-selene-mast" +version = "0.2.0-dev.0" +dependencies = [ + "anyhow", + "pecos-core", + "pecos-simulators", + "pecos-stab-tn", + "selene-core 0.2.1", +] + +[[package]] +name = "pecos-selene-stab-mps" +version = "0.2.0-dev.0" +dependencies = [ + "anyhow", + "pecos-core", + "pecos-simulators", + "pecos-stab-tn", + "selene-core 0.2.1", +] + +[[package]] +name = "pecos-selene-stab-vec" version = "0.2.0-dev.0" dependencies = [ "anyhow", - "clap", "pecos-core", "pecos-simulators", "selene-core 0.2.1", @@ -4216,7 +4471,7 @@ name = "pecos-selene-stabilizer" version = "0.2.0-dev.0" dependencies = [ "anyhow", - "clap", + "clap 4.6.1", "pecos-core", "pecos-simulators", "selene-core 0.2.1", @@ -4247,6 +4502,22 @@ dependencies = [ "wide 1.3.0", ] +[[package]] +name = "pecos-stab-tn" +version = "0.2.0-dev.0" +dependencies = [ + "approx 0.5.1", + "nalgebra", + "num-complex 0.4.6", + "paste", + "pecos-core", + "pecos-quantum", + "pecos-random", + "pecos-simulators", + "rayon", + "thiserror 2.0.18", +] + [[package]] name = "pecos-tesseract" version = "0.2.0-dev.0" @@ -4262,6 +4533,16 @@ dependencies = [ "thiserror 2.0.18", ] +[[package]] +name = "pecos-uf-decoder" +version = "0.2.0-dev.0" +dependencies = [ + "fastrand", + "pecos-decoder-core", + "pecos-random", + "rayon", +] + [[package]] name = "pecos-wasm" version = "0.2.0-dev.0" @@ -4356,6 +4637,14 @@ dependencies = [ "serde", ] +[[package]] +name = "pheap" +version = "0.3.0" +source = "git+https://github.com/yuewuo/mwpf?tag=v0.2.12#b8444428f999457208c4b0956f3f1c745a0ec2d5" +dependencies = [ + "num-traits", +] + [[package]] name = "phf_shared" version = "0.11.3" @@ -4425,9 +4714,9 @@ checksum = "c33a9471896f1c69cecef8d20cbe2f7accd12527ce60845ff44c153bb2a21b49" [[package]] name = "portable-atomic-util" -version = "0.2.6" +version = "0.2.7" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "091397be61a01d4be58e7841595bd4bfedb15f1cd54977d79b8271e94ed799a3" +checksum = "c2a106d1259c23fac8e543272398ae0e3c0b8d33c88ed73d0cc71b0f1d902618" dependencies = [ "portable-atomic", ] @@ -4531,7 +4820,7 @@ checksum = "0d22152487193190344590e4f30e219cf3fe140d9e7a3fdb683d82aa2c5f4156" dependencies = [ "arrayvec 0.5.2", "typed-arena", - "unicode-width", + "unicode-width 0.2.2", ] [[package]] @@ -4544,6 +4833,20 @@ dependencies = [ "syn 2.0.117", ] +[[package]] +name = "prettytable-rs" +version = "0.10.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "eea25e07510aa6ab6547308ebe3c036016d162b8da920dbb079e3ba8acf3d95a" +dependencies = [ + "csv", + "encode_unicode", + "is-terminal", + "lazy_static", + "term", + "unicode-width 0.1.14", +] + [[package]] name = "priority-queue" version = "1.4.0" @@ -4574,6 +4877,30 @@ dependencies = [ "toml_edit", ] +[[package]] +name = "proc-macro-error" +version = "1.0.4" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "da25490ff9892aab3fcf7c36f08cfb902dd3e71ca0f9f9517bea02a73a5ce38c" +dependencies = [ + "proc-macro-error-attr", + "proc-macro2", + "quote", + "syn 1.0.109", + "version_check", +] + +[[package]] +name = "proc-macro-error-attr" +version = "1.0.4" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "a1be40180e52ecc98ad80b184934baf3d0d29f979574e439af5a55274b35f869" +dependencies = [ + "proc-macro2", + "quote", + "version_check", +] + [[package]] name = "proc-macro2" version = "1.0.106" @@ -4610,9 +4937,9 @@ checksum = "4b45fcc2344c680f5025fe57779faef368840d0bd1f42f216291f0dc4ace4744" dependencies = [ "bit-set 0.8.0", "bit-vec 0.8.0", - "bitflags", + "bitflags 2.11.1", "num-traits", - "rand 0.9.3", + "rand 0.9.4", "rand_chacha 0.9.0", "rand_xorshift", "regex-syntax 0.8.10", @@ -4762,7 +5089,7 @@ dependencies = [ "bytes", "getrandom 0.3.4", "lru-slab", - "rand 0.9.3", + "rand 0.9.4", "ring", "rustc-hash 2.1.2", "rustls", @@ -4795,7 +5122,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "5d7aeb420f81a3c9e632e70cf19a36bfeec45e25a749230c1e99c95486946f9f" dependencies = [ "approx 0.5.1", - "clap", + "clap 4.6.1", "derive_more 1.0.0", "env_logger", "itertools 0.13.0", @@ -4803,7 +5130,7 @@ dependencies = [ "ndarray 0.16.1", "num", "openqasm", - "rand 0.8.5", + "rand 0.8.6", "rayon", "regex", "roots", @@ -4845,9 +5172,9 @@ checksum = "dc33ff2d4973d518d823d61aa239014831e521c75da58e3df4840d3f47749d09" [[package]] name = "rand" -version = "0.8.5" +version = "0.8.6" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404" +checksum = "5ca0ecfa931c29007047d1bc58e623ab12e5590e8c7cc53200d5202b69266d8a" dependencies = [ "libc", "rand_chacha 0.3.1", @@ -4857,9 +5184,9 @@ dependencies = [ [[package]] name = "rand" -version = "0.9.3" +version = "0.9.4" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "7ec095654a25171c2124e9e3393a930bddbffdc939556c914957a4c3e0a87166" +checksum = "44c5af06bb1b7d3216d91932aed5265164bf384dc89cd6ba05cf59a35f5f76ea" dependencies = [ "rand_chacha 0.9.0", "rand_core 0.9.5", @@ -4873,7 +5200,7 @@ checksum = "d2e8e8bcc7961af1fdac401278c6a831614941f6164ee3bf4ce61b7edb162207" dependencies = [ "chacha20", "getrandom 0.4.2", - "rand_core 0.10.0", + "rand_core 0.10.1", ] [[package]] @@ -4917,9 +5244,9 @@ dependencies = [ [[package]] name = "rand_core" -version = "0.10.0" +version = "0.10.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "0c8d0fd677905edcbeedbf2edb6494d676f0e98d54d5cf9bda0b061cb8fb8aba" +checksum = "63b8176103e19a2643978565ca18b50549f6101881c443590420e4dc998a3c69" [[package]] name = "rand_distr" @@ -4928,7 +5255,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "6a8615d50dcf34fa31f7ab52692afec947c4dd0ab803cc87cb3b0b4570ff7463" dependencies = [ "num-traits", - "rand 0.9.3", + "rand 0.9.4", ] [[package]] @@ -4964,7 +5291,7 @@ version = "0.8.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "1f0b2cc7bfeef8f0320ca45f88b00157a03c67137022d59393614352d6bf4312" dependencies = [ - "rand_core 0.10.0", + "rand_core 0.10.1", ] [[package]] @@ -5015,9 +5342,9 @@ checksum = "60a357793950651c4ed0f3f52338f53b2f809f32d83a07f72909fa13e4c6c1e3" [[package]] name = "rayon" -version = "1.11.0" +version = "1.12.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "368f01d005bf8fd9b1206fb6fa653e6c4a81ceb1466406b81792d87c5677a58f" +checksum = "fb39b166781f92d482534ef4b4b1b2568f42613b53e5b6c160e24cfbfa30926d" dependencies = [ "either", "rayon-core", @@ -5050,7 +5377,7 @@ version = "0.5.18" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "ed2bf2547551a7053d6fdfafda3f938979645c44812fbfcda098faae3f1a362d" dependencies = [ - "bitflags", + "bitflags 2.11.1", ] [[package]] @@ -5059,7 +5386,7 @@ version = "0.7.4" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "f450ad9c3b1da563fb6948a8e0fb0fb9269711c9c73d9ea1de5058c79c8d643a" dependencies = [ - "bitflags", + "bitflags 2.11.1", ] [[package]] @@ -5106,13 +5433,13 @@ dependencies = [ [[package]] name = "regalloc2" -version = "0.15.0" +version = "0.15.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "952ddbfc6f9f64d006c3efd8c9851a6ba2f2b944ba94730db255d55006e0ffda" +checksum = "de2c52737737f8609e94f975dee22854a2d5c125772d4b1cf292120f4d45c186" dependencies = [ "allocator-api2", "bumpalo", - "hashbrown 0.15.5", + "hashbrown 0.17.0", "log", "rustc-hash 2.1.2", "smallvec", @@ -5174,7 +5501,7 @@ dependencies = [ "ndarray 0.16.1", "ndarray-npy", "num-traits", - "rand 0.8.5", + "rand 0.8.6", "rayon", "serde", "sprs", @@ -5259,7 +5586,7 @@ version = "0.12.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "4147b952f3f819eca0e99527022f7d6a8d05f111aeb0a62960c74eb283bec8fc" dependencies = [ - "bitflags", + "bitflags 2.11.1", "once_cell", "serde", "serde_derive", @@ -5359,7 +5686,7 @@ version = "1.1.4" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "b6fe4565b9518b83ef4f91bb47ce29620ca828bd32cb7e408f0062e9930ba190" dependencies = [ - "bitflags", + "bitflags 2.11.1", "errno", "libc", "linux-raw-sys", @@ -5431,9 +5758,9 @@ checksum = "f87165f0995f63a9fbeea62b64d10b4d9d8e78ec6d7d51fb2125fda7bb36788f" [[package]] name = "rustls-webpki" -version = "0.103.11" +version = "0.103.12" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "20a6af516fea4b20eccceaf166e8aa666ac996208e8a644ce3ef5aa783bc7cd4" +checksum = "8279bb85272c9f10811ae6a6c547ff594d6a7f3c6c6b02ee9726d1d0dcfcdd06" dependencies = [ "aws-lc-rs", "ring", @@ -5461,7 +5788,7 @@ dependencies = [ "num-traits", "petgraph 0.8.3", "priority-queue 2.7.0", - "rand 0.9.3", + "rand 0.9.4", "rand_distr", "rand_pcg", "rayon", @@ -5577,7 +5904,7 @@ version = "3.7.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "b7f4bc775c73d9a02cde8bf7b2ec4c9d12743edf609006c7facc23998404cd1d" dependencies = [ - "bitflags", + "bitflags 2.11.1", "core-foundation", "core-foundation-sys", "libc", @@ -5658,6 +5985,17 @@ dependencies = [ "serde_derive", ] +[[package]] +name = "serde-wasm-bindgen" +version = "0.6.5" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "8302e169f0eddcc139c70f139d19d6467353af16f9fce27e8c30158036a1e16b" +dependencies = [ + "js-sys", + "serde", + "wasm-bindgen", +] + [[package]] name = "serde_core" version = "1.0.228" @@ -5711,6 +6049,15 @@ dependencies = [ "serde_core", ] +[[package]] +name = "serde_variant" +version = "0.1.3" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "0a0068df419f9d9b6488fdded3f1c818522cdea328e02ce9d9f147380265a432" +dependencies = [ + "serde", +] + [[package]] name = "serde_with" version = "3.18.0" @@ -5843,6 +6190,20 @@ dependencies = [ "version_check", ] +[[package]] +name = "slp" +version = "0.2.0" +source = "git+https://github.com/yuewuo/mwpf?tag=v0.2.12#b8444428f999457208c4b0956f3f1c745a0ec2d5" +dependencies = [ + "num-bigint", + "num-rational", + "num-traits", + "pest", + "pest_derive", + "rayon", + "structopt", +] + [[package]] name = "smallvec" version = "1.15.1" @@ -5878,7 +6239,7 @@ version = "0.4.0+sdk-1.4.341.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "d9571ea910ebd84c86af4b3ed27f9dbdc6ad06f17c5f96146b2b671e2976744f" dependencies = [ - "bitflags", + "bitflags 2.11.1", ] [[package]] @@ -5921,12 +6282,42 @@ dependencies = [ "precomputed-hash", ] +[[package]] +name = "strsim" +version = "0.8.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a" + [[package]] name = "strsim" version = "0.11.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f" +[[package]] +name = "structopt" +version = "0.3.26" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "0c6b5c64445ba8094a6ab0c3cd2ad323e07171012d9c98b0b15651daf1787a10" +dependencies = [ + "clap 2.34.0", + "lazy_static", + "structopt-derive", +] + +[[package]] +name = "structopt-derive" +version = "0.4.18" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "dcb5ae327f9cc13b68763b5749770cb9e048a99bd9dfdfa58d0cf05d5f64afe0" +dependencies = [ + "heck 0.3.3", + "proc-macro-error", + "proc-macro2", + "quote", + "syn 1.0.109", +] + [[package]] name = "strum" version = "0.25.0" @@ -5994,6 +6385,18 @@ version = "2.6.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "13c2bddecc57b384dee18652358fb23172facb8a2c51ccc10d74c157bdea3292" +[[package]] +name = "sugar" +version = "0.2.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "616a397f08825a805c27d9a18afcd17d953aee58c1637d078cc1791e1e3e22c1" +dependencies = [ + "cute", + "maplit", + "min_max_macros", + "vec_box", +] + [[package]] name = "syn" version = "1.0.109" @@ -6098,6 +6501,15 @@ version = "0.5.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "8f50febec83f5ee1df3015341d8bd429f2d1cc62bcba7ea2076759d315084683" +[[package]] +name = "textwrap" +version = "0.11.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "d326610f408c7a4eb6f51c37c330e496b08506c9457c9d34287ecc38809fb060" +dependencies = [ + "unicode-width 0.1.14", +] + [[package]] name = "thiserror" version = "1.0.69" @@ -6138,6 +6550,20 @@ dependencies = [ "syn 2.0.117", ] +[[package]] +name = "thread-priority" +version = "1.2.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "cfe075d7053dae61ac5413a34ea7d4913b6e6207844fd726bdd858b37ff72bf5" +dependencies = [ + "bitflags 2.11.1", + "cfg-if", + "libc", + "log", + "rustversion", + "winapi", +] + [[package]] name = "time" version = "0.3.47" @@ -6288,9 +6714,9 @@ dependencies = [ [[package]] name = "tokio" -version = "1.51.1" +version = "1.52.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "f66bf9585cda4b724d3e78ab34b73fb2bbaba9011b9bfdf69dc836382ea13b8c" +checksum = "b67dee974fe86fd92cc45b7a95fdd2f99a36a6d7b0d431a231178d3d670bbcc6" dependencies = [ "bytes", "libc", @@ -6382,7 +6808,7 @@ version = "0.6.8" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "d4e6559d53cc268e5031cd8429d05415bc4cb4aefc4aa5d6cc35fbf5b924a1f8" dependencies = [ - "bitflags", + "bitflags 2.11.1", "bytes", "futures-util", "http", @@ -6509,6 +6935,12 @@ version = "1.13.2" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "9629274872b2bfaf8d66f5f15725007f635594914870f65218920345aa11aa8c" +[[package]] +name = "unicode-width" +version = "0.1.14" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "7dd6e30e90baa6f72411720665d41d89b9a3d039dc45b8faea1ddd07f617f6af" + [[package]] name = "unicode-width" version = "0.2.2" @@ -6581,6 +7013,18 @@ dependencies = [ "wasm-bindgen", ] +[[package]] +name = "vec_box" +version = "1.0.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "c5283fc94a1cd6b5199f707a4b4d7f885b9457d430d111c68a07d3e3d199fb2b" + +[[package]] +name = "vec_map" +version = "0.8.2" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "f1bddf1187be692e79c5ffeab891132dfb0f236ed36a43c7ed39f1165ee20191" + [[package]] name = "version_check" version = "0.9.5" @@ -6742,7 +7186,7 @@ version = "0.244.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "47b807c72e1bac69382b3a6fb3dbe8ea4c0ed87ff5629b8685ae6b9a611028fe" dependencies = [ - "bitflags", + "bitflags 2.11.1", "hashbrown 0.15.5", "indexmap 2.14.0", "semver", @@ -6754,7 +7198,7 @@ version = "0.245.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "4f08c9adee0428b7bddf3890fc27e015ac4b761cc608c822667102b8bfd6995e" dependencies = [ - "bitflags", + "bitflags 2.11.1", "hashbrown 0.16.1", "indexmap 2.14.0", "semver", @@ -6767,7 +7211,7 @@ version = "0.246.2" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "71cde4757396defafd25417cfb36aa3161027d06d865b0c24baaae229aac005d" dependencies = [ - "bitflags", + "bitflags 2.11.1", "indexmap 2.14.0", "semver", ] @@ -6791,7 +7235,7 @@ checksum = "ce205cd643d661b5ba5ba4717e13730262e8cdbc8f2eacbc7b906d45c1a74026" dependencies = [ "addr2line", "async-trait", - "bitflags", + "bitflags 2.11.1", "bumpalo", "cc", "cfg-if", @@ -6956,7 +7400,7 @@ dependencies = [ "bumpalo", "leb128fmt", "memchr", - "unicode-width", + "unicode-width 0.2.2", "wasm-encoder 0.246.2", ] @@ -7009,9 +7453,9 @@ dependencies = [ [[package]] name = "webpki-root-certs" -version = "1.0.6" +version = "1.0.7" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "804f18a4ac2676ffb4e8b5b5fa9ae38af06df08162314f96a68d2a363e21a8ca" +checksum = "f31141ce3fc3e300ae89b78c0dd67f9708061d1d2eda54b8209346fd6be9a92c" dependencies = [ "rustls-pki-types", ] @@ -7023,7 +7467,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "72c239a9a747bbd379590985bac952c2e53cb19873f7072b3370c6a6a8e06837" dependencies = [ "arrayvec 0.7.6", - "bitflags", + "bitflags 2.11.1", "bytemuck", "cfg-if", "cfg_aliases", @@ -7055,7 +7499,7 @@ dependencies = [ "arrayvec 0.7.6", "bit-set 0.9.1", "bit-vec 0.9.1", - "bitflags", + "bitflags 2.11.1", "bytemuck", "cfg_aliases", "document-features", @@ -7116,7 +7560,7 @@ dependencies = [ "arrayvec 0.7.6", "ash", "bit-set 0.9.1", - "bitflags", + "bitflags 2.11.1", "block2", "bytemuck", "cfg-if", @@ -7175,7 +7619,7 @@ version = "29.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "ec2675540fb1a5cfa5ef122d3d5f390e2c75711a0b946410f2d6ac3a0f77d1f6" dependencies = [ - "bitflags", + "bitflags 2.11.1", "bytemuck", "js-sys", "log", @@ -7633,7 +8077,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "9d66ea20e9553b30172b5e831994e35fbde2d165325bec84fc43dbf6f4eb9cb2" dependencies = [ "anyhow", - "bitflags", + "bitflags 2.11.1", "indexmap 2.14.0", "log", "serde", diff --git a/Cargo.toml b/Cargo.toml index 7e2bb9394..955a6c7a2 100644 --- a/Cargo.toml +++ b/Cargo.toml @@ -2,9 +2,14 @@ resolver = "2" members = [ "python/pecos-rslib", + "python/pecos-rslib-exp", "python/pecos-rslib-cuda", "python/pecos-rslib-llvm", - "python/selene-plugins/pecos-selene-*", + "python/selene-plugins/pecos-selene-mast", + "python/selene-plugins/pecos-selene-stab-mps", + "python/selene-plugins/pecos-selene-stab-vec", + "python/selene-plugins/pecos-selene-stabilizer", + "python/selene-plugins/pecos-selene-statevec", "julia/pecos-julia-ffi", "go/pecos-go-ffi", "crates/pecos*", @@ -152,6 +157,7 @@ quizx = "0.3" # --- Decoder libraries --- fusion-blossom = "0.2" +mwpf = { git = "https://github.com/yuewuo/mwpf", tag = "v0.2.12", default-features = false, features = ["f64_weight"] } relay-bp = "0.2" # ndarray 0.16 for relay-bp compat (relay-bp uses ndarray 0.16, PECOS uses 0.17) ndarray-016 = { package = "ndarray", version = "0.16" } @@ -172,6 +178,8 @@ pecos-cuquantum-sys = { version = "0.2.0-dev.0", path = "crates/pecos-cuquantum- pecos-decoder-core = { version = "0.2.0-dev.0", path = "crates/pecos-decoder-core" } pecos-decoders = { version = "0.2.0-dev.0", path = "crates/pecos-decoders" } pecos-engines = { version = "0.2.0-dev.0", path = "crates/pecos-engines" } +pecos-eeg = { version = "0.2.0-dev.0", path = "exp/pecos-eeg" } +pecos-stab-tn = { version = "0.2.0-dev.0", path = "exp/pecos-stab-tn" } pecos-experimental = { version = "0.2.0-dev.0", path = "exp/pecos-experimental" } pecos-foreign = { version = "0.2.0-dev.0", path = "crates/pecos-foreign" } pecos-fusion-blossom = { version = "0.2.0-dev.0", path = "crates/pecos-fusion-blossom" } @@ -180,6 +188,7 @@ pecos-hugr = { version = "0.2.0-dev.0", path = "crates/pecos-hugr" } pecos-hugr-qis = { version = "0.2.0-dev.0", path = "crates/pecos-hugr-qis" } pecos-ldpc-decoders = { version = "0.2.0-dev.0", path = "crates/pecos-ldpc-decoders" } pecos-llvm = { version = "0.2.0-dev.0", path = "crates/pecos-llvm" } +pecos-mwpf = { version = "0.2.0-dev.0", path = "crates/pecos-mwpf" } pecos-neo = { version = "0.2.0-dev.0", path = "exp/pecos-neo" } pecos-num = { version = "0.2.0-dev.0", path = "crates/pecos-num" } pecos-phir = { version = "0.2.0-dev.0", path = "crates/pecos-phir" } @@ -198,6 +207,7 @@ pecos-rslib = { version = "0.2.0-dev.0", path = "python/pecos-rslib" } pecos-rslib-llvm = { version = "0.2.0-dev.0", path = "python/pecos-rslib-llvm" } pecos-simulators = { version = "0.2.0-dev.0", path = "crates/pecos-simulators" } pecos-tesseract = { version = "0.2.0-dev.0", path = "crates/pecos-tesseract" } +pecos-uf-decoder = { version = "0.2.0-dev.0", path = "crates/pecos-uf-decoder" } pecos-wasm = { version = "0.2.0-dev.0", path = "crates/pecos-wasm" } pecos-zx = { version = "0.2.0-dev.0", path = "exp/pecos-zx" } @@ -215,6 +225,14 @@ lto = true # Link-time optimization (same as "fat") codegen-units = 1 # Single codegen unit for better optimization strip = true # Strip debug symbols for smaller binaries +# Profiling profile: release optimizations but keeps debug info for perf/samply. +# Use with: cargo build --profile profiling +# Or: maturin develop --profile profiling +[profile.profiling] +inherits = "release" +strip = false +debug = 1 # line tables only — minimal size impact + # Native profile: release + CPU-specific optimizations # Use with: cargo build --profile native # Build scripts detect this via PROFILE=native env var and add --march=native for C++ code diff --git a/Justfile b/Justfile index 6c8f5cf4e..7033955a0 100644 --- a/Justfile +++ b/Justfile @@ -156,7 +156,7 @@ pytest *args: else uv run pytest python/pecos-rslib/tests -m "not performance" uv run --group numpy-compat pytest python/pecos-rslib/tests -m "numpy and not performance" - uv run pytest python/quantum-pecos/tests -m "not optional_dependency" + uv run pytest python/quantum-pecos/tests -m "not optional_dependency and not slow" uv run pytest python/selene-plugins fi @@ -481,6 +481,11 @@ pytest-dep: uv run pytest python/pecos-rslib/tests -m "optional_dependency" uv run pytest python/quantum-pecos/tests -m "optional_dependency" +# Run the slower integration lane (excluded from the default fast lane) +[group('test')] +pytest-slow: + uv run pytest python/quantum-pecos/tests -m "slow and not optional_dependency" + @@ -497,20 +502,28 @@ setup-quiet: sync-deps: #!/usr/bin/env bash set -euo pipefail - # Quick check: if quantum-pecos is importable, deps are likely fine - if uv run --frozen python -c "import pecos" 2>/dev/null; then + # Quick check: ensure the packages used by the default dev/test lane are importable. + # This catches newly added workspace members that an older .venv may be missing. + if uv run --frozen python -c "import importlib.util, sys; required = ('pecos', 'pecos_rslib', 'pecos_selene_stab_vec', 'pecos_selene_stabilizer', 'pecos_selene_statevec', 'pecos_selene_stab_mps', 'pecos_selene_mast'); missing = [name for name in required if importlib.util.find_spec(name) is None]; sys.exit(1 if missing else 0)" 2>/dev/null; then exit 0 fi - echo "Python deps not installed, running uv sync..." + echo "Python deps incomplete, running uv sync..." uv sync --project . --all-packages [private] build-selene: #!/usr/bin/env bash set -euo pipefail + PLUGIN_DIRS=() + for DIR in python/selene-plugins/pecos-selene-*/; do + [ -d "$DIR" ] || continue + [ -f "$DIR/Cargo.toml" ] || continue + [ -f "$DIR/pyproject.toml" ] || continue + PLUGIN_DIRS+=("$DIR") + done # Check if any selene source changed since last install NEEDS_BUILD=false - for DIR in python/selene-plugins/pecos-selene-*/; do + for DIR in "${PLUGIN_DIRS[@]}"; do PKG=$(basename "$DIR") DEST="$DIR/python/${PKG//-/_}/_dist/lib/" SO=$(find "$DEST" -name "*.so" 2>/dev/null | head -1 || true) @@ -531,7 +544,7 @@ build-selene: fi echo "Building Selene plugins..." CARGO_ARGS="" - for DIR in python/selene-plugins/pecos-selene-*/; do + for DIR in "${PLUGIN_DIRS[@]}"; do CARGO_ARGS="$CARGO_ARGS -p $(basename "$DIR")" done if [ -n "$CARGO_ARGS" ]; then diff --git a/crates/benchmarks/Cargo.toml b/crates/benchmarks/Cargo.toml index 260bd9666..5de039a7f 100644 --- a/crates/benchmarks/Cargo.toml +++ b/crates/benchmarks/Cargo.toml @@ -18,6 +18,7 @@ parallel = ["pecos-simulators/parallel"] gpu-sims = ["dep:pecos-gpu-sims"] cuquantum = ["dep:pecos-cuquantum"] cppsparsestab = ["dep:pecos-cppsparsestab"] +stab-tn = ["dep:pecos-stab-tn"] all-sims = ["gpu-sims", "cuquantum", "cppsparsestab"] [dependencies] @@ -27,6 +28,9 @@ pecos-cuquantum = { workspace = true, optional = true } pecos-cppsparsestab = { workspace = true, optional = true } pecos-core.workspace = true pecos-simulators.workspace = true +pecos-stab-tn = { path = "../../exp/pecos-stab-tn", optional = true } +nalgebra.workspace = true +num-complex.workspace = true [dev-dependencies] criterion.workspace = true diff --git a/crates/benchmarks/benches/benchmarks.rs b/crates/benchmarks/benches/benchmarks.rs index 7c545bf2f..d32dad430 100644 --- a/crates/benchmarks/benches/benchmarks.rs +++ b/crates/benchmarks/benches/benchmarks.rs @@ -17,11 +17,12 @@ use criterion::{Criterion, criterion_group, criterion_main}; mod modules { pub mod allocation_overhead; - pub mod clifford_rz; pub mod cpu_stabilizer_comparison; + pub mod dem_builder; pub mod dem_sampler; pub mod dod_statevec; pub mod quizx_eval; + pub mod stab_vec; // TODO: pub mod hadamard_ops; #[cfg(feature = "cuquantum")] pub mod cuquantum; @@ -33,6 +34,8 @@ mod modules { #[cfg(feature = "cppsparsestab")] pub mod sparse_stab_vs_cpp; pub mod sparse_stab_w_vs_y; + #[cfg(feature = "stab-tn")] + pub mod stab_mps_vs_stab_vec; // TODO: pub mod pauli_ops; pub mod pecos_neo_comparison; pub mod rng; @@ -50,20 +53,23 @@ use modules::cuquantum; use modules::gpu_influence_sampler; #[cfg(feature = "cppsparsestab")] use modules::sparse_stab_vs_cpp; +#[cfg(feature = "stab-tn")] +use modules::stab_mps_vs_stab_vec; use modules::{ - allocation_overhead, clifford_rz, cpu_stabilizer_comparison, dem_sampler, dod_statevec, + allocation_overhead, cpu_stabilizer_comparison, dem_builder, dem_sampler, dod_statevec, measurement_sampling, native_statevec_comparison, noise_models, pecos_neo_comparison, - quizx_eval, rng, set_ops, sparse_stab_w_vs_y, sparse_state_vec, stabilizer_sims, + quizx_eval, rng, set_ops, sparse_stab_w_vs_y, sparse_state_vec, stab_vec, stabilizer_sims, state_vec_sims, surface_code, trig, }; fn all_benchmarks(c: &mut Criterion) { allocation_overhead::benchmarks(c); - clifford_rz::benchmarks(c); + stab_vec::benchmarks(c); cpu_stabilizer_comparison::benchmarks(c); quizx_eval::benchmarks(c); #[cfg(feature = "cuquantum")] cuquantum::benchmarks(c); + dem_builder::benchmarks(c); dem_sampler::benchmarks(c); dod_statevec::benchmarks(c); #[cfg(feature = "gpu-sims")] @@ -81,6 +87,8 @@ fn all_benchmarks(c: &mut Criterion) { sparse_stab_vs_cpp::benchmarks(c); sparse_stab_w_vs_y::benchmarks(c); surface_code::benchmarks(c); + #[cfg(feature = "stab-tn")] + stab_mps_vs_stab_vec::benchmarks(c); trig::benchmarks(c); // TODO: pauli_ops::benchmarks(c); // TODO: hadamard_ops::benchmarks(c); diff --git a/crates/benchmarks/benches/modules/dem_builder.rs b/crates/benchmarks/benches/modules/dem_builder.rs new file mode 100644 index 000000000..13883cf99 --- /dev/null +++ b/crates/benchmarks/benches/modules/dem_builder.rs @@ -0,0 +1,165 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! DEM construction and decomposition benchmarks. +//! +//! These benchmarks exercise `DetectorErrorModel::to_string()` and the two +//! decomposed-output paths (`to_string_decomposed`, `to_string_decomposed_maximally`) +//! on surface-code-like DEMs of increasing distance. Decomposition exercises the +//! hot maps inside `dem_builder/types.rs` (`candidates_by_detector`, the memoization +//! caches inside `find_hyperedge_decomposition` / `find_singleton_decomposition`, +//! and the render-side `rendered_targets_cache`). These are the structures whose +//! HashMap/BTreeMap choice has been debated; this bench gives the numbers to +//! settle it. + +use criterion::{BenchmarkId, Criterion, Throughput, measurement::Measurement}; +use pecos_qec::fault_tolerance::dem_builder::{DemBuilder, DetectorErrorModel}; +use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; +use pecos_quantum::DagCircuit; +use std::fmt::Write; +use std::hint::black_box; + +pub fn benchmarks(c: &mut Criterion) { + bench_dem_build(c); + bench_dem_render(c); + bench_dem_render_decomposed(c); + bench_dem_render_decomposed_maximally(c); +} + +/// Build a surface-code-like DAG and its fault influence map. +/// +/// Mirrors the simplified construction in `dem_sampler.rs`. Not a true surface +/// code, but produces correlated multi-detector errors that exercise the DEM +/// decomposition paths. +fn build_surface_code_dem(distance: usize, rounds: usize) -> DetectorErrorModel { + let num_data = distance * distance; + let num_ancilla = num_data - 1; + + let mut dag = DagCircuit::new(); + + for q in 0..num_data { + dag.pz(&[q]); + dag.h(&[q]); + } + + for _round in 0..rounds { + for a in 0..num_ancilla { + dag.pz(&[num_data + a]); + } + for a in 0..num_ancilla { + let ancilla = num_data + a; + let d1 = a % num_data; + let d2 = (a + 1) % num_data; + dag.cx(&[(ancilla, d1)]); + dag.cx(&[(ancilla, d2)]); + } + for a in 0..num_ancilla { + dag.mz(&[num_data + a]); + } + } + + let analyzer = DagFaultAnalyzer::new(&dag); + let influence_map = analyzer.build_influence_map(); + + // Detectors: each ancilla measurement after the first round XORed with the + // previous round's measurement of the same ancilla. This produces typical + // 2-detector graphlike mechanisms plus some higher-weight correlated errors. + let mut detectors = String::from("["); + let mut first = true; + let mut det_id: u32 = 0; + for round in 1..rounds { + for a in 0..num_ancilla { + #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] + let curr = -((round * num_ancilla - a) as i32); + #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] + let prev = -(((round + 1) * num_ancilla - a) as i32); + if !first { + detectors.push(','); + } + write!(detectors, r#"{{"id":{det_id},"records":[{curr},{prev}]}}"#) + .expect("writing to String cannot fail"); + det_id += 1; + first = false; + } + } + detectors.push(']'); + + DemBuilder::new(&influence_map) + .with_noise(0.001, 0.001, 0.001, 0.001) + .with_detectors_json(&detectors) + .expect("detectors json should parse") + .with_observables_json("[]") + .expect("observables json should parse") + .build() +} + +fn bench_dem_build(c: &mut Criterion) { + let mut group = c.benchmark_group("dem_builder/build"); + for &(distance, rounds) in &[(3usize, 3usize), (5, 5), (7, 5)] { + let num_contribs_hint = distance * distance * rounds; + #[allow(clippy::cast_possible_truncation)] + group.throughput(Throughput::Elements(num_contribs_hint as u64)); + group.bench_with_input( + BenchmarkId::from_parameter(format!("d{distance}_r{rounds}")), + &(distance, rounds), + |b, &(d, r)| { + b.iter(|| black_box(build_surface_code_dem(black_box(d), black_box(r)))); + }, + ); + } + group.finish(); +} + +fn bench_dem_render(c: &mut Criterion) { + let mut group = c.benchmark_group("dem_builder/render_plain"); + for &(distance, rounds) in &[(3usize, 3usize), (5, 5), (7, 5)] { + let dem = build_surface_code_dem(distance, rounds); + group.bench_with_input( + BenchmarkId::from_parameter(format!("d{distance}_r{rounds}")), + &dem, + |b, dem| { + b.iter(|| black_box(dem.to_string())); + }, + ); + } + group.finish(); +} + +fn bench_dem_render_decomposed(c: &mut Criterion) { + let mut group = c.benchmark_group("dem_builder/render_decomposed"); + for &(distance, rounds) in &[(3usize, 3usize), (5, 5), (7, 5)] { + let dem = build_surface_code_dem(distance, rounds); + group.bench_with_input( + BenchmarkId::from_parameter(format!("d{distance}_r{rounds}")), + &dem, + |b, dem| { + b.iter(|| black_box(dem.to_string_decomposed())); + }, + ); + } + group.finish(); +} + +fn bench_dem_render_decomposed_maximally(c: &mut Criterion) { + let mut group = c.benchmark_group("dem_builder/render_decomposed_maximally"); + for &(distance, rounds) in &[(3usize, 3usize), (5, 5), (7, 5)] { + let dem = build_surface_code_dem(distance, rounds); + group.bench_with_input( + BenchmarkId::from_parameter(format!("d{distance}_r{rounds}")), + &dem, + |b, dem| { + b.iter(|| black_box(dem.to_string_decomposed_maximally())); + }, + ); + } + group.finish(); +} diff --git a/crates/benchmarks/benches/modules/dem_sampler.rs b/crates/benchmarks/benches/modules/dem_sampler.rs index b46a2feac..42353ae76 100644 --- a/crates/benchmarks/benches/modules/dem_sampler.rs +++ b/crates/benchmarks/benches/modules/dem_sampler.rs @@ -11,30 +11,17 @@ // the License. //! DEM Sampler benchmarks for threshold estimation. -//! -//! These benchmarks measure the performance of the DEM-based sampling -//! infrastructure used for fast error threshold estimation. -//! -//! # Benchmarks -//! -//! - **DEM Sampler - Original vs Columnar**: Compare row-major vs column-major sampling -//! - **DEM Sampler - Statistics**: Compare statistics-only methods -//! - **DEM Sampler - Scaling**: How different methods scale with DEM size - -use std::str::FromStr; use criterion::{BenchmarkId, Criterion, Throughput, measurement::Measurement}; -use pecos_qec::fault_tolerance::dem_builder::{DemSamplerBuilder, ParsedDem}; +use pecos_qec::fault_tolerance::dem_builder::DemSamplerBuilder; use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; use pecos_quantum::DagCircuit; use pecos_random::PecosRng; use std::hint::black_box; pub fn benchmarks(c: &mut Criterion) { - bench_sampler_comparison(c); - bench_statistics_comparison(c); - bench_optimization_comparison(c); - bench_parsed_dem_sampling(c); + bench_sampler(c); + bench_statistics(c); } /// Create a realistic DEM sampler from a surface-code-like circuit. @@ -45,48 +32,40 @@ fn create_surface_code_sampler( // Create a simplified surface code circuit let num_data = distance * distance; let num_ancilla = num_data - 1; + let total_qubits = num_data + num_ancilla; let mut dag = DagCircuit::new(); - // Initialize data qubits - for q in 0..num_data { - dag.pz(&[q]); - dag.h(&[q]); - } + // Prep all qubits + let all_qubits: Vec = (0..total_qubits).collect(); + dag.pz(&all_qubits); // Syndrome extraction rounds - for _round in 0..rounds { - // Initialize ancillas - for a in 0..num_ancilla { - dag.pz(&[num_data + a]); - } - - // Entangle ancillas with data (simplified pattern) + let ancilla_qubits: Vec = (num_data..total_qubits).collect(); + for _ in 0..rounds { + dag.h(&ancilla_qubits); for a in 0..num_ancilla { - let ancilla = num_data + a; - let d1 = a % num_data; - let d2 = (a + 1) % num_data; - dag.cx(&[(ancilla, d1)]); - dag.cx(&[(ancilla, d2)]); - } - - // Measure ancillas - for a in 0..num_ancilla { - dag.mz(&[num_data + a]); + let data_q = a.min(num_data - 1); + dag.cx(&[(data_q, num_data + a)]); } + dag.h(&ancilla_qubits); + dag.mz(&ancilla_qubits); + dag.pz(&ancilla_qubits); } - // Build influence map and sampler + // Measure data qubits + let data_qubits: Vec = (0..num_data).collect(); + dag.mz(&data_qubits); + + // Build influence map let analyzer = DagFaultAnalyzer::new(&dag); let influence_map = analyzer.build_influence_map(); - // Create detector definitions (one per ancilla measurement) - let num_measurements = num_ancilla * rounds; + // Build DEM sampler with simple detectors + let num_measurements = num_ancilla * rounds + num_data; let mut detector_records = Vec::new(); for i in 0..num_measurements.min(50) { - // Limit to 50 detectors for benchmark #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] - // i < 50, fits in i32 detector_records.push(vec![-(i as i32 + 1)]); } @@ -95,48 +74,31 @@ fn create_surface_code_sampler( .with_detector_records(detector_records) .with_observable_records(vec![]) .build() + .expect("Failed to build DEM sampler") } -/// Benchmark comparing original row-major vs columnar sampling. -fn bench_sampler_comparison(c: &mut Criterion) { - let mut group = c.benchmark_group("DEM Sampler - Original vs Columnar"); +/// Benchmark sampling with different circuit sizes. +fn bench_sampler(c: &mut Criterion) { + let mut group = c.benchmark_group("DEM Sampler - Batch"); - // Test with different circuit sizes for (distance, rounds) in [(3, 2), (5, 3)] { let sampler = create_surface_code_sampler(distance, rounds); let num_mechanisms = sampler.num_mechanisms(); let num_detectors = sampler.num_detectors(); - // Test different shot counts for shots in [1_000, 10_000, 100_000] { let label = format!("d{distance}_r{rounds}_{shots}"); - group.throughput(Throughput::Elements((num_mechanisms * shots) as u64)); - // Original row-major sampling - group.bench_with_input(BenchmarkId::new("row_major", &label), &(), |b, ()| { + group.bench_with_input(BenchmarkId::new("sample_batch", &label), &(), |b, ()| { let mut rng = PecosRng::seed_from_u64(42); b.iter(|| { let result = sampler.sample_batch(shots, &mut rng); black_box(result) }); }); - - // Columnar sampling (accurate - one random per shot per mechanism) - group.bench_with_input( - BenchmarkId::new("columnar_accurate", &label), - &(), - |b, ()| { - let mut rng = PecosRng::seed_from_u64(42); - b.iter(|| { - let result = sampler.sample_batch_columnar_accurate(shots, &mut rng); - black_box(result) - }); - }, - ); } - // Print info println!( " d={distance} r={rounds}: {num_mechanisms} mechanisms, {num_detectors} detectors" ); @@ -145,261 +107,29 @@ fn bench_sampler_comparison(c: &mut Criterion) { group.finish(); } -/// Benchmark comparing statistics methods. -fn bench_statistics_comparison(c: &mut Criterion) { +/// Benchmark statistics methods. +fn bench_statistics(c: &mut Criterion) { let mut group = c.benchmark_group("DEM Sampler - Statistics"); let sampler = create_surface_code_sampler(5, 3); let num_mechanisms = sampler.num_mechanisms(); - for shots in [10_000, 100_000, 1_000_000] { + for shots in [10_000, 100_000] { let label = format!("{shots}shots"); - group.throughput(Throughput::Elements((num_mechanisms * shots) as u64)); - // Original statistics (row-major) group.bench_with_input( - BenchmarkId::new("row_major", &label), + BenchmarkId::new("sample_statistics", &label), &shots, |b, &shots| { let mut rng = PecosRng::seed_from_u64(42); b.iter(|| { - let result = sampler.sample_statistics_row_major(shots, &mut rng); + let result = sampler.sample_statistics_with_rng(shots, &mut rng); black_box(result) }); }, ); - - // Columnar statistics - group.bench_with_input(BenchmarkId::new("columnar", &label), &shots, |b, &shots| { - let mut rng = PecosRng::seed_from_u64(42); - b.iter(|| { - let result = sampler.sample_statistics_columnar(shots, &mut rng); - black_box(result) - }); - }); - } - - group.finish(); -} - -/// Benchmark comparing all optimization methods. -fn bench_optimization_comparison(c: &mut Criterion) { - let mut group = c.benchmark_group("DEM Sampler - Optimizations"); - - // Use a realistic surface code sampler - let sampler = create_surface_code_sampler(5, 3); - let num_mechanisms = sampler.num_mechanisms(); - - let shots = 100_000; - group.throughput(Throughput::Elements((num_mechanisms * shots) as u64)); - - // Baseline: current columnar_accurate - group.bench_function("columnar_accurate", |b| { - let mut rng = PecosRng::seed_from_u64(42); - b.iter(|| { - let result = sampler.sample_batch_columnar_accurate(shots, &mut rng); - black_box(result) - }); - }); - - // SIMD u64x4 version - group.bench_function("simd_u64x4", |b| { - let mut rng = PecosRng::seed_from_u64(42); - b.iter(|| { - let result = sampler.sample_batch_columnar_simd(shots, &mut rng); - black_box(result) - }); - }); - - // Geometric skip version (fastest for low error rates) - group.bench_function("geometric", |b| { - let mut rng = PecosRng::seed_from_u64(42); - b.iter(|| { - let result = sampler.sample_batch_columnar_geometric(shots, &mut rng); - black_box(result) - }); - }); - - group.finish(); - - // Also compare statistics methods - let mut stats_group = c.benchmark_group("DEM Sampler - Stats Optimizations"); - stats_group.throughput(Throughput::Elements((num_mechanisms * shots) as u64)); - - stats_group.bench_function("stats_columnar", |b| { - let mut rng = PecosRng::seed_from_u64(42); - b.iter(|| { - let result = sampler.sample_statistics_columnar(shots, &mut rng); - black_box(result) - }); - }); - - stats_group.bench_function("stats_simd", |b| { - let mut rng = PecosRng::seed_from_u64(42); - b.iter(|| { - let result = sampler.sample_statistics_simd(shots, &mut rng); - black_box(result) - }); - }); - - stats_group.bench_function("stats_geometric", |b| { - let mut rng = PecosRng::seed_from_u64(42); - b.iter(|| { - let result = sampler.sample_statistics_geometric(shots, &mut rng); - black_box(result) - }); - }); - - stats_group.bench_function("stats_auto", |b| { - let mut rng = PecosRng::seed_from_u64(42); - b.iter(|| { - let result = sampler.sample_statistics_with_rng(shots, &mut rng); - black_box(result) - }); - }); - - stats_group.bench_function("stats_parallel", |b| { - b.iter(|| { - let result = sampler.sample_statistics_parallel(shots, 42); - black_box(result) - }); - }); - - stats_group.finish(); - - // Benchmark parallel scaling with larger DEM - bench_parallel_scaling(c); -} - -/// Benchmark parallel scaling with different DEM sizes. -fn bench_parallel_scaling(c: &mut Criterion) { - let mut group = c.benchmark_group("DEM Sampler - Parallel Scaling"); - - let shots = 100_000; - - // Test with different circuit sizes - for (distance, rounds) in [(3, 2), (5, 3), (7, 5)] { - let sampler = create_surface_code_sampler(distance, rounds); - let num_mechanisms = sampler.num_mechanisms(); - let label = format!("d{distance}_r{rounds}_{num_mechanisms}mech"); - - group.throughput(Throughput::Elements((num_mechanisms * shots) as u64)); - - // Sequential geometric (baseline) - group.bench_with_input(BenchmarkId::new("sequential", &label), &(), |b, ()| { - let mut rng = PecosRng::seed_from_u64(42); - b.iter(|| { - let result = sampler.sample_statistics_geometric(shots, &mut rng); - black_box(result) - }); - }); - - // Parallel - group.bench_with_input(BenchmarkId::new("parallel", &label), &(), |b, ()| { - b.iter(|| { - let result = sampler.sample_statistics_parallel(shots, 42); - black_box(result) - }); - }); - - // Auto (should pick geometric for low p) - group.bench_with_input(BenchmarkId::new("auto", &label), &(), |b, ()| { - let mut rng = PecosRng::seed_from_u64(42); - b.iter(|| { - let result = sampler.sample_statistics_with_rng(shots, &mut rng); - black_box(result) - }); - }); } group.finish(); } - -/// Create a synthetic DEM string for benchmarking. -fn create_synthetic_dem(num_mechanisms: usize, num_detectors: usize, prob: f64) -> String { - use std::fmt::Write; - - let mut dem = String::new(); - - for i in 0..num_detectors { - writeln!(dem, "detector({i}, 0, 0) D{i}").unwrap(); - } - - for i in 0..num_mechanisms { - let d1 = i % num_detectors; - let d2 = (i + 1) % num_detectors; - let d3 = (i + 2) % num_detectors; - - match i % 3 { - 0 => writeln!(dem, "error({prob}) D{d1}").unwrap(), - 1 => writeln!(dem, "error({prob}) D{d1} D{d2}").unwrap(), - _ => writeln!(dem, "error({prob}) D{d1} D{d2} D{d3}").unwrap(), - } - } - - dem -} - -/// Benchmark `ParsedDem` sampling (used by equivalence testing). -fn bench_parsed_dem_sampling(c: &mut Criterion) { - let mut group = c.benchmark_group("ParsedDem - Sampling"); - - let medium_dem = create_synthetic_dem(50, 24, 0.01); - let complex_dem = create_synthetic_dem(200, 96, 0.01); - - let dems: [(&str, &str); 3] = [ - ( - "simple", - "error(0.01) D0\nerror(0.01) D1\nerror(0.01) D0 D1", - ), - ("medium", &medium_dem), - ("complex", &complex_dem), - ]; - - let shots = 50_000; - - for (name, dem_str) in &dems { - let dem = ParsedDem::from_str(dem_str).expect("failed to parse DEM"); - let num_mechanisms = dem.mechanisms.len(); - - group.throughput(Throughput::Elements((num_mechanisms * shots) as u64)); - - group.bench_with_input(BenchmarkId::new("sample_batch", *name), &(), |b, ()| { - let mut rng = PecosRng::seed_from_u64(42); - b.iter(|| { - let result = dem.sample_batch(shots, &mut rng); - black_box(result) - }); - }); - } - - group.finish(); -} - -#[cfg(test)] -mod tests { - - #[test] - fn test_sampler_creation() { - let sampler = create_surface_code_sampler(3, 1); - assert!(sampler.num_mechanisms() > 0); - } - - #[test] - fn test_columnar_matches_row_major() { - let sampler = create_surface_code_sampler(3, 1); - - // Sample with row-major - let mut rng1 = PecosRng::seed_from_u64(42); - let stats1 = sampler.sample_statistics(1000, &mut rng1); - - // Sample with columnar - let mut rng2 = PecosRng::seed_from_u64(42); - let stats2 = sampler.sample_statistics_columnar(1000, &mut rng2); - - // Statistics should be similar (not exact due to different RNG consumption order) - // Just verify both produce reasonable results - assert!(stats1.total_shots == stats2.total_shots); - } -} diff --git a/crates/benchmarks/benches/modules/gpu_influence_sampler.rs b/crates/benchmarks/benches/modules/gpu_influence_sampler.rs index ecb305548..990b5122c 100644 --- a/crates/benchmarks/benches/modules/gpu_influence_sampler.rs +++ b/crates/benchmarks/benches/modules/gpu_influence_sampler.rs @@ -20,7 +20,7 @@ use criterion::{BenchmarkId, Criterion, Throughput, measurement::Measurement}; use pecos_gpu_sims::{GpuInfluenceMapData, GpuInfluenceSampler}; -use pecos_qec::fault_tolerance::noisy_sampler::{NoisySampler, UniformNoiseModel}; +use pecos_qec::fault_tolerance::dem_builder::DemSampler; use pecos_qec::fault_tolerance::{DagFaultInfluenceMap, InfluenceBuilder}; use pecos_quantum::DagCircuit; use std::hint::black_box; @@ -105,31 +105,44 @@ fn build_influence_maps( circuit: &DagCircuit, num_data: usize, ) -> (DagFaultInfluenceMap, GpuInfluenceMapData) { - let logical_qubits: Vec = (0..num_data).collect(); - let builder = InfluenceBuilder::new(circuit).with_logical_z(logical_qubits); + let tracked_op_qubits: Vec = (0..num_data).collect(); + let builder = InfluenceBuilder::new(circuit).with_z(&tracked_op_qubits); let influence_map = builder.build(); let ( num_loc, num_det, - num_log, + num_dem_outputs, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, det_data_z, - log_off_x, - log_data_x, - log_off_y, - log_data_y, - log_off_z, - log_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ) = influence_map.export_csr(); let gpu_map = GpuInfluenceMapData::from_csr( - num_loc, num_det, num_log, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, - det_data_z, log_off_x, log_data_x, log_off_y, log_data_y, log_off_z, log_data_z, + num_loc, + num_det, + num_dem_outputs, + det_off_x, + det_data_x, + det_off_y, + det_data_y, + det_off_z, + det_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ); (influence_map, gpu_map) @@ -155,11 +168,11 @@ fn bench_cpu_vs_gpu_surface_codes(c: &mut Criterion) { group.throughput(Throughput::Elements(u64::from(num_shots))); // CPU benchmark - let noise = UniformNoiseModel::depolarizing(p_error); - let mut cpu_sampler = NoisySampler::new(&cpu_map, noise, seed); + let probs = vec![p_error; cpu_map.locations.len()]; + let cpu_sampler = DemSampler::from_influence_map(&cpu_map, &probs); group.bench_with_input(BenchmarkId::new("CPU", &label), &(), |b, ()| { - b.iter(|| black_box(cpu_sampler.sample(num_shots as usize))); + b.iter(|| black_box(cpu_sampler.sample_statistics(num_shots as usize, seed))); }); // GPU benchmark @@ -196,11 +209,11 @@ fn bench_gpu_sampler_shot_scaling(c: &mut Criterion) { group.throughput(Throughput::Elements(u64::from(num_shots))); // CPU benchmark - let noise = UniformNoiseModel::depolarizing(p_error); - let mut cpu_sampler = NoisySampler::new(&cpu_map, noise, seed); + let probs = vec![p_error; cpu_map.locations.len()]; + let cpu_sampler = DemSampler::from_influence_map(&cpu_map, &probs); group.bench_with_input(BenchmarkId::new("CPU", &label), &num_shots, |b, &shots| { - b.iter(|| black_box(cpu_sampler.sample(shots as usize))); + b.iter(|| black_box(cpu_sampler.sample_statistics(shots as usize, seed))); }); // GPU benchmark diff --git a/crates/benchmarks/benches/modules/quizx_eval.rs b/crates/benchmarks/benches/modules/quizx_eval.rs index f81595753..57e980048 100644 --- a/crates/benchmarks/benches/modules/quizx_eval.rs +++ b/crates/benchmarks/benches/modules/quizx_eval.rs @@ -13,7 +13,7 @@ //! Evaluate `QuiZX` circuit simplification for T-count reduction. //! //! Tests whether ZX-calculus simplification meaningfully reduces the number -//! of non-Clifford gates in circuits relevant to the `CliffordRz` simulator. +//! of non-Clifford gates in circuits relevant to the `StabVec` simulator. use criterion::{BenchmarkId, Criterion, measurement::Measurement}; use quizx::circuit::Circuit; diff --git a/crates/benchmarks/benches/modules/stab_mps_vs_stab_vec.rs b/crates/benchmarks/benches/modules/stab_mps_vs_stab_vec.rs new file mode 100644 index 000000000..93f35bce4 --- /dev/null +++ b/crates/benchmarks/benches/modules/stab_mps_vs_stab_vec.rs @@ -0,0 +1,404 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Performance benchmarks: STN vs `StabVec`. +//! +//! Measures wall time for the same circuits on both simulators to find +//! the crossover point where STN becomes faster. +//! +//! Run: `cargo bench -p pecos-stab-tn` + +use criterion::{BenchmarkId, Criterion, measurement::Measurement}; +use nalgebra::DMatrix; +use num_complex::Complex64; +use pecos_core::{Angle64, QubitId}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, StabVec}; +use pecos_stab_tn::mps::svd; +use pecos_stab_tn::stab_mps::StabMps; +use pecos_stab_tn::stab_mps::mast::Mast; +use std::hint::black_box; + +pub fn benchmarks(c: &mut Criterion) { + bench_vary_t_count(c); + bench_vary_qubits(c); + bench_measurement(c); + bench_stab_mps_at_scale(c); + bench_mast_vs_stn(c); + bench_disentangling(c); + bench_svd_comparison(c); + bench_adaptive_truncation(c); +} + +/// Build a random Clifford+T circuit and run it. +fn run_circuit(sim: &mut S, num_qubits: usize, num_t_gates: usize) { + let t = Angle64::QUARTER_TURN / 2u64; + + // Clifford entangling layer + for q in 0..num_qubits { + sim.h(&[QubitId(q)]); + } + for q in 0..num_qubits - 1 { + sim.cx(&[(QubitId(q), QubitId(q + 1))]); + } + + // T gates on rotating qubits + for i in 0..num_t_gates { + let q = i % num_qubits; + sim.rz(t, &[QubitId(q)]); + } + + // Another Clifford layer + for q in (0..num_qubits - 1).rev() { + sim.cx(&[(QubitId(q + 1), QubitId(q))]); + } + for q in 0..num_qubits { + sim.h(&[QubitId(q)]); + } +} + +/// Benchmark: vary T-gate count at fixed qubit count. +fn bench_vary_t_count(c: &mut Criterion) { + let mut group = c.benchmark_group("STN vs CRZ: vary T-count (10 qubits)"); + group.sample_size(10); + + let num_qubits = 10; + for &num_t in &[2, 4, 8, 12, 16, 20] { + group.bench_with_input(BenchmarkId::new("StabVec", num_t), &num_t, |b, &nt| { + b.iter(|| { + let mut sim = StabVec::builder(num_qubits).seed(42).build(); + run_circuit(&mut sim, num_qubits, nt); + black_box(&sim); + }); + }); + + group.bench_with_input(BenchmarkId::new("STN", num_t), &num_t, |b, &nt| { + b.iter(|| { + let mut sim = StabMps::builder(num_qubits).seed(42).build(); + run_circuit(&mut sim, num_qubits, nt); + black_box(&sim); + }); + }); + } + group.finish(); +} + +/// Benchmark: vary qubit count at fixed T-gate count. +fn bench_vary_qubits(c: &mut Criterion) { + let mut group = c.benchmark_group("STN vs CRZ: vary qubits (8 T gates)"); + group.sample_size(10); + + let num_t = 8; + for &num_qubits in &[4, 8, 16, 32, 64] { + group.bench_with_input( + BenchmarkId::new("StabVec", num_qubits), + &num_qubits, + |b, &nq| { + b.iter(|| { + let mut sim = StabVec::builder(nq).seed(42).build(); + run_circuit(&mut sim, nq, num_t); + black_box(&sim); + }); + }, + ); + + group.bench_with_input( + BenchmarkId::new("STN", num_qubits), + &num_qubits, + |b, &nq| { + b.iter(|| { + let mut sim = StabMps::builder(nq).seed(42).build(); + run_circuit(&mut sim, nq, num_t); + black_box(&sim); + }); + }, + ); + } + group.finish(); +} + +/// Benchmark: measurement cost comparison. +fn bench_measurement(c: &mut Criterion) { + let mut group = c.benchmark_group("STN vs CRZ: measurement (10 qubits, 8 T)"); + group.sample_size(10); + + let num_qubits = 10; + let num_t = 8; + + group.bench_function("StabVec", |b| { + b.iter(|| { + let mut sim = StabVec::builder(num_qubits).seed(42).build(); + run_circuit(&mut sim, num_qubits, num_t); + let results = sim.mz(&(0..num_qubits).map(QubitId).collect::>()); + black_box(&results); + }); + }); + + group.bench_function("STN", |b| { + b.iter(|| { + let mut sim = StabMps::builder(num_qubits).seed(42).build(); + run_circuit(&mut sim, num_qubits, num_t); + let results = sim.mz(&(0..num_qubits).map(QubitId).collect::>()); + black_box(&results); + }); + }); + + group.finish(); +} + +/// Benchmark: MAST vs STN at varying T-count. +fn bench_mast_vs_stn(c: &mut Criterion) { + let mut group = c.benchmark_group("MAST vs STN: vary T-count (20 qubits)"); + group.sample_size(10); + + let num_qubits = 20; + for &num_t in &[4, 8, 16, 20] { + group.bench_with_input(BenchmarkId::new("STN", num_t), &num_t, |b, &nt| { + b.iter(|| { + let mut sim = StabMps::builder(num_qubits).seed(42).build(); + run_circuit(&mut sim, num_qubits, nt); + black_box(&sim); + }); + }); + + group.bench_with_input(BenchmarkId::new("MAST", num_t), &num_t, |b, &nt| { + b.iter(|| { + let mut sim = Mast::with_seed(num_qubits, nt + 2, 42); + run_circuit(&mut sim, num_qubits, nt); + sim.mz(&[QubitId(0)]); // Force projection + black_box(&sim); + }); + }); + } + group.finish(); +} + +/// Benchmark: STN at scale (CRZ can't do this). +fn bench_stab_mps_at_scale(c: &mut Criterion) { + let mut group = c.benchmark_group("STN at scale"); + group.sample_size(10); + + for &num_qubits in &[50, 100, 200] { + let num_t = num_qubits / 2; + group.bench_with_input( + BenchmarkId::new("STN circuit", num_qubits), + &num_qubits, + |b, &nq| { + b.iter(|| { + let mut sim = StabMps::builder(nq).seed(42).build(); + run_circuit(&mut sim, nq, num_t); + black_box(&sim); + }); + }, + ); + } + group.finish(); +} + +/// Build a "hard" circuit: interleaved Clifford + T layers that create real MPS entanglement. +/// Each layer: CX chain + T on all qubits. Repeats `depth` times. +fn run_interleaved_circuit( + sim: &mut S, + num_qubits: usize, + depth: usize, +) { + let t = Angle64::QUARTER_TURN / 2u64; + + for layer in 0..depth { + // Clifford entangling: H + CX chain (alternating direction) + for q in 0..num_qubits { + sim.h(&[QubitId(q)]); + } + if layer % 2 == 0 { + for q in 0..num_qubits - 1 { + sim.cx(&[(QubitId(q), QubitId(q + 1))]); + } + } else { + for q in (0..num_qubits - 1).rev() { + sim.cx(&[(QubitId(q + 1), QubitId(q))]); + } + } + + // T gate on every qubit + for q in 0..num_qubits { + sim.rz(t, &[QubitId(q)]); + } + } +} + +/// Benchmark: disentangling cost and effectiveness. +/// +/// Measures wall time and bond dim reduction from heuristic disentangling. +/// This provides the baseline for comparing against OFD. +fn bench_disentangling(c: &mut Criterion) { + let mut group = c.benchmark_group("STN disentangling"); + group.sample_size(10); + + // Use the interleaved circuit which creates real MPS entanglement + let num_qubits = 10; + for &depth in &[1, 2, 3] { + let label = format!("{num_qubits}q/depth{depth}"); + + group.bench_with_input(BenchmarkId::new("no_disent", &label), &depth, |b, &d| { + b.iter(|| { + let mut sim = StabMps::builder(num_qubits).seed(42).build(); + run_interleaved_circuit(&mut sim, num_qubits, d); + black_box(sim.max_bond_dim()); + }); + }); + + group.bench_with_input( + BenchmarkId::new("heuristic_1sweep", &label), + &depth, + |b, &d| { + b.iter(|| { + let mut sim = StabMps::builder(num_qubits).seed(42).build(); + run_interleaved_circuit(&mut sim, num_qubits, d); + sim.disentangle(1); + black_box(sim.max_bond_dim()); + }); + }, + ); + + group.bench_with_input( + BenchmarkId::new("heuristic_3sweeps", &label), + &depth, + |b, &d| { + b.iter(|| { + let mut sim = StabMps::builder(num_qubits).seed(42).build(); + run_interleaved_circuit(&mut sim, num_qubits, d); + sim.disentangle(3); + black_box(sim.max_bond_dim()); + }); + }, + ); + } + group.finish(); + + // Report bond dims and GF(2) diagnostic for reference + eprintln!("\n=== Bond dimension report (interleaved circuits) ==="); + for &depth in &[1, 2, 3] { + let mut sim = StabMps::builder(num_qubits).seed(42).build(); + run_interleaved_circuit(&mut sim, num_qubits, depth); + let before = sim.max_bond_dim(); + let gf2_rank = sim.gf2_matrix().gf2_rank(); + let gf2_gates = sim.gf2_matrix().num_gates(); + let gf2_min = sim.theoretical_min_bond_dim(); + let applied = sim.disentangle(3); + let after = sim.max_bond_dim(); + eprintln!( + " {num_qubits}q/depth{depth}: bond_dim {before} -> {after} ({applied} gates), GF2: {gf2_gates} gates rank {gf2_rank} (theory min {gf2_min})" + ); + } +} + +/// Benchmark: full SVD vs randomized SVD at various matrix sizes. +/// +/// The randomized SVD (Halko-Martinsson-Tropp) gives O(mnr) cost vs +/// O(mn*min(m,n)) for full SVD. This benchmark measures the crossover. +fn bench_svd_comparison(c: &mut Criterion) { + let mut group = c.benchmark_group("SVD full vs randomized"); + group.sample_size(10); + + // Generate a test matrix of given size with known rank structure + let make_matrix = |rows: usize, cols: usize| -> DMatrix { + DMatrix::from_fn(rows, cols, |i, j| { + let r = (i * 7 + j * 13 + 5) & 0xFFFF; + let c = (i * 3 + j * 11 + 2) & 0xFFFF; + Complex64::new(f64::from(r as u16).sin(), f64::from(c as u16).cos()) + }) + }; + + for &(rows, cols, max_rank) in &[ + (64, 64, 8), // Small matrix, heavy truncation + (128, 128, 16), // Medium matrix + (256, 256, 32), // Large matrix -- rSVD should win here + (512, 512, 32), // Very large -- rSVD should win clearly + ] { + let label = format!("{rows}x{cols}/r{max_rank}"); + let m = make_matrix(rows, cols); + + group.bench_with_input(BenchmarkId::new("full_svd", &label), &m, |b, matrix| { + b.iter(|| { + let result = svd::truncated_svd(matrix, max_rank, 1e-12).unwrap(); + black_box(result.singular_values.len()); + }); + }); + + group.bench_with_input(BenchmarkId::new("auto_svd", &label), &m, |b, matrix| { + b.iter(|| { + let result = svd::truncated_svd_auto(matrix, max_rank, 1e-12).unwrap(); + black_box(result.singular_values.len()); + }); + }); + } + group.finish(); +} + +/// Benchmark: adaptive truncation (error-budget) vs fixed `max_bond_dim`. +fn bench_adaptive_truncation(c: &mut Criterion) { + let mut group = c.benchmark_group("STN adaptive truncation"); + group.sample_size(10); + + let num_qubits = 20; + let depth = 2; + + // Fixed max_bond_dim = 64 (default) + group.bench_function("fixed_chi64", |b| { + b.iter(|| { + let mut sim = StabMps::builder(num_qubits).seed(42).build(); + run_interleaved_circuit(&mut sim, num_qubits, depth); + black_box(sim.max_bond_dim()); + }); + }); + + // Adaptive with error budget 1e-6, cap 64 + group.bench_function("adaptive_1e-6_cap64", |b| { + b.iter(|| { + let mut sim = StabMps::builder(num_qubits) + .seed(42) + .max_truncation_error(1e-6) + .build(); + run_interleaved_circuit(&mut sim, num_qubits, depth); + black_box(sim.max_bond_dim()); + }); + }); + + // Adaptive with error budget 1e-3, cap 64 + group.bench_function("adaptive_1e-3_cap64", |b| { + b.iter(|| { + let mut sim = StabMps::builder(num_qubits) + .seed(42) + .max_truncation_error(1e-3) + .build(); + run_interleaved_circuit(&mut sim, num_qubits, depth); + black_box(sim.max_bond_dim()); + }); + }); + + group.finish(); + + // Report bond dims + eprintln!("\n=== Adaptive truncation report ({num_qubits}q, depth {depth}) ==="); + for &(label, err) in &[ + ("fixed", -1.0), + ("adaptive_1e-6", 1e-6), + ("adaptive_1e-3", 1e-3), + ] { + let mut builder = StabMps::builder(num_qubits).seed(42); + if err > 0.0 { + builder = builder.max_truncation_error(err); + } + let mut sim = builder.build(); + run_interleaved_circuit(&mut sim, num_qubits, depth); + eprintln!(" {label}: max_bond_dim = {}", sim.max_bond_dim()); + } +} diff --git a/crates/benchmarks/benches/modules/clifford_rz.rs b/crates/benchmarks/benches/modules/stab_vec.rs similarity index 92% rename from crates/benchmarks/benches/modules/clifford_rz.rs rename to crates/benchmarks/benches/modules/stab_vec.rs index 83a4706c6..04a69e83b 100644 --- a/crates/benchmarks/benches/modules/clifford_rz.rs +++ b/crates/benchmarks/benches/modules/stab_vec.rs @@ -21,7 +21,7 @@ use criterion::{BenchmarkId, Criterion, measurement::Measurement}; use pecos_core::{Angle64, QubitId}; use pecos_simulators::{ - ArbitraryRotationGateable, CHForm, CliffordGateable, CliffordRz, QuantumSimulator, SparseStab, + ArbitraryRotationGateable, CHForm, CliffordGateable, QuantumSimulator, SparseStab, StabVec, }; use std::hint::black_box; @@ -89,11 +89,11 @@ fn bench_rz_term_growth(c: &mut Criterion) { let num_qubits = 2; for &num_rz in &[1, 2, 4, 6, 8] { group.bench_with_input( - BenchmarkId::new("CliffordRz", format!("{num_rz}_rz")), + BenchmarkId::new("StabVec", format!("{num_rz}_rz")), &num_rz, |b, &nrz| { b.iter(|| { - let mut sim = CliffordRz::new_with_seed(num_qubits, 42); + let mut sim = StabVec::new_with_seed(num_qubits, 42); sim.h(&[QubitId(0)]).h(&[QubitId(1)]); for i in 0..nrz { let theta = Angle64::from_radians(0.3 + 0.1 * i as f64); @@ -119,7 +119,7 @@ fn bench_state_vector(c: &mut Criterion) { BenchmarkId::new("2_terms", format!("{num_qubits}q")), &num_qubits, |b, &nq| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); sim.h(&[QubitId(0)]); if nq > 1 { sim.cx(&[(QubitId(0), QubitId(1))]); @@ -140,7 +140,7 @@ fn bench_state_vector(c: &mut Criterion) { BenchmarkId::new(format!("{terms}_terms"), format!("{nq}q_vary_terms")), &num_rz, |b, &nrz| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } @@ -162,7 +162,7 @@ fn bench_state_vector(c: &mut Criterion) { /// Benchmark measurement cost. #[allow(clippy::cast_precision_loss)] // small loop index as f64 fn bench_measurement(c: &mut Criterion) { - let mut group = c.benchmark_group("CliffordRz Measurement"); + let mut group = c.benchmark_group("StabVec Measurement"); group.sample_size(20); for &num_rz in &[1, 2, 3, 4] { @@ -172,7 +172,7 @@ fn bench_measurement(c: &mut Criterion) { &num_rz, |b, &nrz| { b.iter(|| { - let mut sim = CliffordRz::new_with_seed(4, 42); + let mut sim = StabVec::new_with_seed(4, 42); for q in 0..4 { sim.h(&[QubitId(q)]); } @@ -244,7 +244,7 @@ fn bench_inner_product(c: &mut Criterion) { /// Benchmark ONLY the measurement call (circuit pre-built). fn bench_measurement_only(c: &mut Criterion) { - let mut group = c.benchmark_group("CliffordRz Measurement Only"); + let mut group = c.benchmark_group("StabVec Measurement Only"); group.sample_size(10); for &num_qubits in &[4, 8, 14, 18, 22] { @@ -253,7 +253,7 @@ fn bench_measurement_only(c: &mut Criterion) { &num_qubits, |b, &nq| { // Pre-build the circuit state - let mut template = CliffordRz::new_with_seed(nq, 42); + let mut template = StabVec::new_with_seed(nq, 42); for q in 0..nq { template.h(&[QubitId(q)]); } @@ -299,7 +299,7 @@ fn bench_clone_cost(c: &mut Criterion) { /// Benchmark measurement at higher qubit counts to show where O(2^n) becomes the bottleneck. fn bench_measurement_scaling(c: &mut Criterion) { - let mut group = c.benchmark_group("CliffordRz Measurement Scaling"); + let mut group = c.benchmark_group("StabVec Measurement Scaling"); group.sample_size(10); // Fixed 2 RZ gates (4 terms), vary qubit count @@ -309,7 +309,7 @@ fn bench_measurement_scaling(c: &mut Criterion) { &num_qubits, |b, &nq| { b.iter(|| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } @@ -344,7 +344,7 @@ fn bench_realistic_circuit(c: &mut Criterion) { BenchmarkId::new("20_H_gates", format!("{terms}_terms")), &num_rz, |b, &nrz| { - let mut template = CliffordRz::new_with_seed(num_qubits, 42); + let mut template = StabVec::new_with_seed(num_qubits, 42); for q in 0..num_qubits { template.h(&[QubitId(q)]); } @@ -365,7 +365,7 @@ fn bench_realistic_circuit(c: &mut Criterion) { // Benchmark 1: Clifford-only portion (no term doubling) group.bench_function("20q_clifford_only_4terms", |b| { // Pre-build a 4-term state - let mut template = CliffordRz::new_with_seed(num_qubits, 42); + let mut template = StabVec::new_with_seed(num_qubits, 42); for q in 0..num_qubits { template.h(&[QubitId(q)]); } @@ -385,7 +385,7 @@ fn bench_realistic_circuit(c: &mut Criterion) { // Benchmark 2: Single RZ (doubles terms from 4 to 8) group.bench_function("20q_single_rz_4to8terms", |b| { - let mut template = CliffordRz::new_with_seed(num_qubits, 42); + let mut template = StabVec::new_with_seed(num_qubits, 42); for q in 0..num_qubits { template.h(&[QubitId(q)]); } @@ -401,7 +401,7 @@ fn bench_realistic_circuit(c: &mut Criterion) { // Benchmark 3: Measurement on 4-term, 20-qubit state group.bench_function("20q_measurement_4terms", |b| { - let mut template = CliffordRz::new_with_seed(num_qubits, 42); + let mut template = StabVec::new_with_seed(num_qubits, 42); for q in 0..num_qubits { template.h(&[QubitId(q)]); } @@ -429,7 +429,7 @@ fn bench_rz_commutation_opportunity(c: &mut Criterion) { // Pattern: RZ(q) - S(q) - RZ(q). S commutes with RZ, so these could fuse. group.bench_function("rz_S_rz_same_qubit", |b| { b.iter(|| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } @@ -444,7 +444,7 @@ fn bench_rz_commutation_opportunity(c: &mut Criterion) { // Pattern: RZ(q) - CZ(q,r) - RZ(q). CZ is diagonal, commutes with RZ. group.bench_function("rz_CZ_rz_same_qubit", |b| { b.iter(|| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } @@ -460,7 +460,7 @@ fn bench_rz_commutation_opportunity(c: &mut Criterion) { group.bench_function("rz_fused_ideal", |b| { let fused = Angle64::from_radians(0.6); b.iter(|| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } @@ -486,7 +486,7 @@ fn bench_t_gate_patterns(c: &mut Criterion) { // Pattern: T gates on same qubit fuse (T*T = S = Clifford) group.bench_function("4T_same_qubit_fuses_to_Z", |b| { b.iter(|| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } @@ -503,7 +503,7 @@ fn bench_t_gate_patterns(c: &mut Criterion) { // Pattern: T on different qubits (no fusion possible) group.bench_function("4T_different_qubits", |b| { b.iter(|| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } @@ -519,7 +519,7 @@ fn bench_t_gate_patterns(c: &mut Criterion) { // Pattern: T-Clifford-T interleaved on same qubit group.bench_function("T_CZ_T_same_qubit", |b| { b.iter(|| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } @@ -545,7 +545,7 @@ fn bench_rz_fusion_opportunity(c: &mut Criterion) { // Without fusion: 4 separate RZ gates on same qubit = 16 terms group.bench_function("4_separate_rz_same_qubit", |b| { b.iter(|| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } @@ -562,7 +562,7 @@ fn bench_rz_fusion_opportunity(c: &mut Criterion) { group.bench_function("1_fused_rz_same_qubit", |b| { let fused_theta = Angle64::from_radians(0.3 * 4.0); b.iter(|| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } @@ -586,7 +586,7 @@ fn bench_small_angle_rz(c: &mut Criterion) { group.bench_function("10_rz_5deg_different_qubits", |b| { let theta = Angle64::from_radians(5.0f64.to_radians()); b.iter(|| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } @@ -602,7 +602,7 @@ fn bench_small_angle_rz(c: &mut Criterion) { group.bench_function("10_rz_1deg_different_qubits", |b| { let theta = Angle64::from_radians(1.0f64.to_radians()); b.iter(|| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } @@ -632,7 +632,7 @@ fn bench_end_to_end(c: &mut Criterion) { |b, &nrz| { let theta = Angle64::from_radians(0.3); b.iter(|| { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); // Initial Clifford layer for q in 0..nq { sim.h(&[QubitId(q)]); diff --git a/crates/benchmarks/examples/profile_dem_decomposition.rs b/crates/benchmarks/examples/profile_dem_decomposition.rs new file mode 100644 index 000000000..466f3371c --- /dev/null +++ b/crates/benchmarks/examples/profile_dem_decomposition.rs @@ -0,0 +1,90 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Standalone hot-loop around `DetectorErrorModel::to_string_decomposed_maximally()`, +//! used to drive `samply` / `cargo flamegraph` while investigating the +//! HashMap/BTreeMap/Vec tradeoff in `dem_builder/types.rs`. + +use pecos_qec::fault_tolerance::dem_builder::{DemBuilder, DetectorErrorModel}; +use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; +use pecos_quantum::DagCircuit; +use std::fmt::Write; +use std::hint::black_box; + +fn build_surface_code_dem(distance: usize, rounds: usize) -> DetectorErrorModel { + let num_data = distance * distance; + let num_ancilla = num_data - 1; + + let mut dag = DagCircuit::new(); + + for q in 0..num_data { + dag.pz(&[q]); + dag.h(&[q]); + } + + for _round in 0..rounds { + for a in 0..num_ancilla { + dag.pz(&[num_data + a]); + } + for a in 0..num_ancilla { + let ancilla = num_data + a; + let d1 = a % num_data; + let d2 = (a + 1) % num_data; + dag.cx(&[(ancilla, d1)]); + dag.cx(&[(ancilla, d2)]); + } + for a in 0..num_ancilla { + dag.mz(&[num_data + a]); + } + } + + let analyzer = DagFaultAnalyzer::new(&dag); + let influence_map = analyzer.build_influence_map(); + + let mut detectors = String::from("["); + let mut first = true; + let mut det_id: u32 = 0; + for round in 1..rounds { + for a in 0..num_ancilla { + #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] + let curr = -((round * num_ancilla - a) as i32); + #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] + let prev = -(((round + 1) * num_ancilla - a) as i32); + if !first { + detectors.push(','); + } + write!(detectors, r#"{{"id":{det_id},"records":[{curr},{prev}]}}"#) + .expect("writing to String cannot fail"); + det_id += 1; + first = false; + } + } + detectors.push(']'); + + DemBuilder::new(&influence_map) + .with_noise(0.001, 0.001, 0.001, 0.001) + .with_detectors_json(&detectors) + .expect("detectors json should parse") + .with_observables_json("[]") + .expect("observables json should parse") + .build() +} + +fn main() { + // d=7 r=5 matches the slowest bench case (~17 ms per iter). + // 200 iterations -> ~3.4 seconds of hot-path work, enough for samply. + let dem = build_surface_code_dem(7, 5); + for _ in 0..200 { + let out = dem.to_string_decomposed_maximally(); + black_box(out); + } +} diff --git a/crates/pecos-build/src/download.rs b/crates/pecos-build/src/download.rs index a11b3bf72..69e84953e 100644 --- a/crates/pecos-build/src/download.rs +++ b/crates/pecos-build/src/download.rs @@ -50,7 +50,7 @@ pub fn download_cached(info: &DownloadInfo) -> Result> { log::info!("Downloading {} (will be cached)", info.name); let client = reqwest::blocking::Client::builder() - .timeout(std::time::Duration::from_secs(300)) + .timeout(std::time::Duration::from_mins(5)) .connect_timeout(std::time::Duration::from_secs(30)) .build() .map_err(|e| Error::Http(e.to_string()))?; diff --git a/crates/pecos-build/src/llvm/installer.rs b/crates/pecos-build/src/llvm/installer.rs index 36fe30091..2351d6097 100644 --- a/crates/pecos-build/src/llvm/installer.rs +++ b/crates/pecos-build/src/llvm/installer.rs @@ -191,7 +191,7 @@ fn download_and_verify_with_retry(url: &str, dest: &PathBuf, archive_name: &str) } // Check for empty downloads (CDN/rate limit issues) - let file_size = fs::metadata(dest).map(|m| m.len()).unwrap_or(0); + let file_size = fs::metadata(dest).map_or(0, |m| m.len()); if file_size == 0 { if attempt < MAX_RETRIES { eprintln!("Download returned empty file (possible CDN issue)"); diff --git a/crates/pecos-chromobius/Cargo.toml b/crates/pecos-chromobius/Cargo.toml index f945d9a24..6b1528949 100644 --- a/crates/pecos-chromobius/Cargo.toml +++ b/crates/pecos-chromobius/Cargo.toml @@ -13,6 +13,7 @@ description = "Chromobius color code decoder for PECOS" [dependencies] pecos-decoder-core.workspace = true +pecos-pymatching.workspace = true ndarray.workspace = true thiserror.workspace = true cxx.workspace = true diff --git a/crates/pecos-chromobius/build_chromobius.rs b/crates/pecos-chromobius/build_chromobius.rs index 75a27a1dc..108c6cfdc 100644 --- a/crates/pecos-chromobius/build_chromobius.rs +++ b/crates/pecos-chromobius/build_chromobius.rs @@ -59,7 +59,24 @@ pub fn build() -> Result<()> { let manifest = Manifest::find_and_load_validated()?; let chromobius_dir = ensure_dep_ready("chromobius", &manifest)?; let stim_dir = ensure_dep_ready("stim", &manifest)?; - let pymatching_dir = ensure_dep_ready("pymatching", &manifest)?; + // PyMatching headers and compiled objects come from pecos-pymatching via cargo metadata. + // This avoids compiling a second copy of PyMatching sources which would cause + // duplicate symbol errors at link time. + let pymatching_include = env::var("DEP_PYMATCHING_PECOS_PYMATCHING_INCLUDE").map_or_else(|_| { + // Fallback: download and use directly (for standalone builds) + ensure_dep_ready("pymatching", &manifest) + .expect("pymatching dependency") + .join("src") + }, PathBuf::from); + let stim_include = env::var("DEP_PYMATCHING_PECOS_STIM_INCLUDE").map_or_else(|_| { + ensure_dep_ready("stim", &manifest) + .expect("stim dependency") + .join("src") + }, PathBuf::from); + let stim_dir_for_header = env::var("DEP_PYMATCHING_PECOS_STIM_DIR").map_or_else(|_| ensure_dep_ready("stim", &manifest).expect("stim dependency"), PathBuf::from); + let pymatching_lib_dir = env::var("DEP_PYMATCHING_PECOS_LIB_DIR") + .ok() + .map(PathBuf::from); // Apply compatibility patches for newer Stim version chromobius_patch::patch_chromobius_for_newer_stim(&chromobius_dir)?; @@ -67,21 +84,34 @@ pub fn build() -> Result<()> { // Generate amalgamated stim.h if needed build_stim::generate_amalgamated_header(&stim_dir)?; - // Build using cxx - build_cxx_bridge(&chromobius_dir, &stim_dir, &pymatching_dir)?; + // Build using cxx -- only chromobius and stim sources, NOT pymatching + build_cxx_bridge( + &chromobius_dir, + &stim_dir, + &pymatching_include, + &stim_include, + &stim_dir_for_header, + pymatching_lib_dir.as_deref(), + )?; Ok(()) } -fn build_cxx_bridge(chromobius_dir: &Path, stim_dir: &Path, pymatching_dir: &Path) -> Result<()> { +fn build_cxx_bridge( + chromobius_dir: &Path, + stim_dir: &Path, + pymatching_include: &Path, + stim_include: &Path, + stim_dir_for_header: &Path, + pymatching_lib_dir: Option<&Path>, +) -> Result<()> { let chromobius_src_dir = chromobius_dir.join("src"); let stim_src_dir = stim_dir.join("src"); - let pymatching_src_dir = pymatching_dir.join("src"); - // Find essential source files + // Find essential source files -- only chromobius and stim, NOT pymatching. + // PyMatching objects come from pecos-pymatching (linked, not compiled here). let chromobius_files = collect_chromobius_sources(&chromobius_src_dir)?; let stim_files = build_stim::collect_stim_sources(&stim_src_dir); - let pymatching_files = collect_pymatching_sources(&pymatching_src_dir)?; // Build the cxx bridge first to generate headers let mut build = cxx_build::bridge("src/bridge.rs"); @@ -101,18 +131,17 @@ fn build_cxx_bridge(chromobius_dir: &Path, stim_dir: &Path, pymatching_dir: &Pat build.file(file); } - // Add PyMatching files - for file in pymatching_files { - build.file(file); - } + // PyMatching objects are provided by pecos-pymatching -- NOT compiled here. + // We only need headers for compilation, not source files. // Configure build build .std("c++20") .include(&chromobius_src_dir) .include(&stim_src_dir) - .include(stim_dir) // For amalgamated stim.h - .include(&pymatching_src_dir) + .include(stim_dir_for_header) // For amalgamated stim.h + .include(pymatching_include) // PyMatching headers (from pecos-pymatching) + .include(stim_include) // Stim headers .include("include") .include("src") .define("CHROMOBIUS_BRIDGE_EXPORTS", None); @@ -173,6 +202,12 @@ fn build_cxx_bridge(chromobius_dir: &Path, stim_dir: &Path, pymatching_dir: &Pat build.compile("chromobius-bridge"); + // Link against pecos-pymatching's compiled PyMatching objects + if let Some(lib_dir) = pymatching_lib_dir { + println!("cargo:rustc-link-search=native={}", lib_dir.display()); + println!("cargo:rustc-link-lib=static=pymatching-bridge"); + } + // On macOS, link against the system C++ library if target.contains("darwin") { println!("cargo:rustc-link-search=native=/usr/lib"); @@ -193,19 +228,6 @@ fn collect_chromobius_sources(chromobius_src_dir: &Path) -> Result> Ok(files) } -fn collect_pymatching_sources(pymatching_src_dir: &Path) -> Result> { - let mut files = Vec::new(); - - // PyMatching sparse_blossom implementation files - let sparse_blossom_dir = pymatching_src_dir.join("pymatching/sparse_blossom"); - if sparse_blossom_dir.exists() { - collect_cc_files_filtered(&sparse_blossom_dir, &mut files)?; - } - - info!("Found {} PyMatching source files", files.len()); - Ok(files) -} - fn collect_cc_files_filtered(dir: &Path, files: &mut Vec) -> Result<()> { for entry in fs::read_dir(dir)? { let entry = entry?; diff --git a/crates/pecos-chromobius/pecos.toml b/crates/pecos-chromobius/pecos.toml index 4c4f5c34d..0d19b9545 100644 --- a/crates/pecos-chromobius/pecos.toml +++ b/crates/pecos-chromobius/pecos.toml @@ -4,19 +4,16 @@ version = 1 [dependencies.chromobius] -version = "35e289570fdc1d71e73582e1fd4e0c8e29298ef5" -url = "https://github.com/quantumlib/chromobius/archive/35e289570fdc1d71e73582e1fd4e0c8e29298ef5.tar.gz" -sha256 = "da73d819e67572065fd715db45fabb342c2a2a1e961d2609df4f9864b9836054" +version = "acd09febcd6d4c9001b4d708507c8bfb10e4322e" +url = "https://github.com/quantumlib/chromobius/archive/acd09febcd6d4c9001b4d708507c8bfb10e4322e.tar.gz" +sha256 = "4aff65fbf3e5a4ed2974f9a48b772274ffa6129daa4b82bfc4182808cbe6360f" description = "Color code decoder" -[dependencies.pymatching] -version = "2b72b2c558eec678656da20ab6c358aa123fb664" -url = "https://github.com/oscarhiggott/PyMatching/archive/2b72b2c558eec678656da20ab6c358aa123fb664.tar.gz" -sha256 = "1470520b66ad7899f85020664aeeadfc6e2967f0b5e19ad205829968b845cd70" -description = "MWPM decoder" +# PyMatching is NOT downloaded here -- pecos-pymatching provides the compiled +# objects and headers via cargo metadata (links = "pymatching-pecos"). [dependencies.stim] -version = "bd60b73525fd5a9b30839020eb7554ad369e4337" -url = "https://github.com/quantumlib/Stim/archive/bd60b73525fd5a9b30839020eb7554ad369e4337.tar.gz" -sha256 = "2a4be24295ce3018d79e08369b31e401a2d33cd8b3a75675d57dac3afd9de37d" +version = "213275795e49027772bea7c610b6aac3a80583e1" +url = "https://github.com/quantumlib/Stim/archive/213275795e49027772bea7c610b6aac3a80583e1.tar.gz" +sha256 = "b63c4ae94494a8819d440757776cf80a829ec1e30454fa7c9b0f670e981938ab" description = "Stabilizer simulator for QEC" diff --git a/crates/pecos-cli/src/cli/rust_cmd.rs b/crates/pecos-cli/src/cli/rust_cmd.rs index f1e6828a1..a891d97f7 100644 --- a/crates/pecos-cli/src/cli/rust_cmd.rs +++ b/crates/pecos-cli/src/cli/rust_cmd.rs @@ -168,8 +168,7 @@ fn is_tool_available(tool: &str) -> bool { Command::new(tool) .args(["--version"]) .output() - .map(|o| o.status.success()) - .unwrap_or(false) + .is_ok_and(|o| o.status.success()) } /// Run a cargo command and return success status @@ -374,6 +373,8 @@ fn run_test(release: bool, include_ffi: bool) -> Result<()> { println!("Testing workspace packages..."); // runtime = sim + qasm + phir (format parsers) // hugr = qis (includes llvm) + hugr compilation + // pecos-cli is excluded here and tested separately below with --features=runtime + // to ensure the pecos binary has PHIR/QIS support for integration tests. let mut args: Vec<&str> = vec!["test", "--workspace", "--features=runtime,hugr"]; for crate_name in FFI_CRATES { @@ -385,6 +386,8 @@ fn run_test(release: bool, include_ffi: bool) -> Result<()> { "--exclude", "pecos-cuquantum", // Requires cuQuantum SDK, test separately if available "--exclude", + "pecos-cli", // Test separately with --features=runtime (see below) + "--exclude", "pecos-decoders", "--exclude", "pecos-gpu-sims", // Always exclude from workspace test, test separately if GPU available @@ -398,6 +401,22 @@ fn run_test(release: bool, include_ffi: bool) -> Result<()> { return Err(Error::Config("cargo test (workspace) failed".to_string())); } + // Test pecos-cli separately with --features=runtime. + // cargo test --workspace --features=runtime overwrites the pecos binary + // WITHOUT runtime features (cargo feature unification bug), so the CLI + // integration tests that invoke `cargo_bin!("pecos")` would get a broken + // binary. Testing separately ensures the binary is built correctly. + println!("Testing pecos-cli with runtime features..."); + let mut cli_args: Vec<&str> = vec!["test", "-p", "pecos-cli", "--features=runtime"]; + if !release_flag.is_empty() { + cli_args.push(release_flag); + } + if !run_cargo_command(&cli_args) { + return Err(Error::Config( + "cargo test (pecos-cli with runtime) failed".to_string(), + )); + } + // Test cuQuantum if SDK is available (requires both CUDA and cuQuantum) if probe_cuquantum_availability() { println!("cuQuantum runtime available - testing pecos-cuquantum"); diff --git a/crates/pecos-cli/src/cli/selene_cmd.rs b/crates/pecos-cli/src/cli/selene_cmd.rs index 51134b5c8..b16ddcaaf 100644 --- a/crates/pecos-cli/src/cli/selene_cmd.rs +++ b/crates/pecos-cli/src/cli/selene_cmd.rs @@ -377,7 +377,7 @@ fn run_list() -> Result<()> { let installed_lib = dist_dir.join(&lib_filename); if installed_lib.exists() { - let size = installed_lib.metadata().map(|m| m.len()).unwrap_or(0); + let size = installed_lib.metadata().map_or(0, |m| m.len()); println!(" (installed, {size} bytes)"); } else { println!(" (not installed)"); diff --git a/crates/pecos-core/src/circuit_diagram.rs b/crates/pecos-core/src/circuit_diagram.rs index 96eb03b4a..9ee1dc550 100644 --- a/crates/pecos-core/src/circuit_diagram.rs +++ b/crates/pecos-core/src/circuit_diagram.rs @@ -1303,13 +1303,13 @@ impl CircuitDiagram { let fill_hex = t.fill.strip_prefix('#').unwrap_or(&t.fill); let stroke_hex = t.stroke.strip_prefix('#').unwrap_or(&t.stroke); let text_hex = t.text.strip_prefix('#').unwrap_or(&t.text); - writeln!(out, " \\definecolor{{{name}Fill}}{{HTML}}{{{fill_hex}}}",).unwrap(); + writeln!(out, " \\definecolor{{{name}Fill}}{{HTML}}{{{fill_hex}}}").unwrap(); writeln!( out, " \\definecolor{{{name}Stroke}}{{HTML}}{{{stroke_hex}}}", ) .unwrap(); - writeln!(out, " \\definecolor{{{name}Text}}{{HTML}}{{{text_hex}}}",).unwrap(); + writeln!(out, " \\definecolor{{{name}Text}}{{HTML}}{{{text_hex}}}").unwrap(); } // Styles. @@ -1537,7 +1537,7 @@ impl CircuitDiagram { match cell { DiagramCell::Wire => { - writeln!(out, " {node_id} [label=\"\", shape=point, width=0.01];",) + writeln!(out, " {node_id} [label=\"\", shape=point, width=0.01];") .unwrap(); } DiagramCell::Gate(s, family) => { @@ -1569,7 +1569,7 @@ impl CircuitDiagram { .unwrap(); } DiagramCell::Crossing | DiagramCell::Connector => { - writeln!(out, " {node_id} [label=\"\", shape=point, width=0.05];",) + writeln!(out, " {node_id} [label=\"\", shape=point, width=0.05];") .unwrap(); } DiagramCell::LabeledConnector(s) => { diff --git a/crates/pecos-core/src/clifford_simplify.rs b/crates/pecos-core/src/clifford_simplify.rs index 9b3cc3554..e3caf97e2 100644 --- a/crates/pecos-core/src/clifford_simplify.rs +++ b/crates/pecos-core/src/clifford_simplify.rs @@ -79,59 +79,32 @@ pub fn try_simplify_rotation(gate: GateType, angle: A64) -> Option { /// |-----------|---------------|---------------| /// | 0 | any | I | /// | pi/2 | 0 | SX | +/// | pi/2 | pi | `SXdg` | /// | pi/2 | pi/2 | SY | +/// | pi/2 | 3pi/2 | `SYdg` | /// | pi | 0 or pi | X | /// | pi | pi/2 or 3pi/2 | Y | -/// | 3pi/2 | 0 | `SXdg` | -/// | 3pi/2 | pi/2 | `SYdg` | +/// | 3pi/2 | 0 | `SXdg` | +/// | 3pi/2 | pi | SX | +/// | 3pi/2 | pi/2 | `SYdg` | +/// | 3pi/2 | 3pi/2 | SY | /// -/// For theta=pi, phi=pi (rotation about -X) and phi=3pi/2 (rotation about -Y) -/// are equivalent to X and Y respectively up to global phase, which does not -/// affect stabilizer simulation or measurement outcomes. +/// A negative axis flips the sign of the rotation angle. That only collapses to +/// the same Clifford up to global phase for half-turns (`pi`), not for the +/// quarter-turn sqrt gates. #[must_use] pub fn try_simplify_r1xy(theta: A64, phi: A64) -> Option { if theta == A64::ZERO { return Some(GateType::I); } - // Determine which axis: X-like (phi = 0 or pi) or Y-like (phi = pi/2 or 3pi/2). - // phi=pi is the -X axis and phi=3pi/2 is the -Y axis; these are equivalent - // to the positive axis up to global phase for Clifford gates. - let is_x_axis = phi == A64::ZERO || phi == A64::HALF_TURN; - let is_y_axis = phi == A64::QUARTER_TURN || phi == A64::THREE_QUARTERS_TURN; - - if !is_x_axis && !is_y_axis { - return None; - } - - // Half turn: full Pauli gate - if theta == A64::HALF_TURN || theta == neg(A64::HALF_TURN) { - return if is_x_axis { - Some(GateType::X) - } else { - Some(GateType::Y) - }; - } - - // Quarter turn: sqrt gate - if theta == A64::QUARTER_TURN { - return if is_x_axis { - Some(GateType::SX) - } else { - Some(GateType::SY) - }; - } - - // Three-quarter turn: sqrt-dagger gate - if theta == A64::THREE_QUARTERS_TURN || theta == neg(A64::QUARTER_TURN) { - return if is_x_axis { - Some(GateType::SXdg) - } else { - Some(GateType::SYdg) - }; + match phi { + A64::ZERO => simplify_rx(theta), + A64::HALF_TURN => simplify_rx(-theta), + A64::QUARTER_TURN => simplify_ry(theta), + A64::THREE_QUARTERS_TURN => simplify_ry(-theta), + _ => None, } - - None } // ------------------------------------------------------------------------- @@ -469,6 +442,16 @@ mod tests { try_simplify_r1xy(Angle64::QUARTER_TURN, Angle64::QUARTER_TURN), Some(GateType::SY) ); + // theta=pi/2, phi=pi: rotation about -X is SXdg + assert_eq!( + try_simplify_r1xy(Angle64::QUARTER_TURN, Angle64::HALF_TURN), + Some(GateType::SXdg) + ); + // theta=pi/2, phi=3pi/2: rotation about -Y is SYdg + assert_eq!( + try_simplify_r1xy(Angle64::QUARTER_TURN, Angle64::THREE_QUARTERS_TURN), + Some(GateType::SYdg) + ); } #[test] @@ -483,6 +466,16 @@ mod tests { try_simplify_r1xy(Angle64::THREE_QUARTERS_TURN, Angle64::QUARTER_TURN), Some(GateType::SYdg) ); + // theta=3pi/2, phi=pi: rotation about -X is SX + assert_eq!( + try_simplify_r1xy(Angle64::THREE_QUARTERS_TURN, Angle64::HALF_TURN), + Some(GateType::SX) + ); + // theta=3pi/2, phi=3pi/2: rotation about -Y is SY + assert_eq!( + try_simplify_r1xy(Angle64::THREE_QUARTERS_TURN, Angle64::THREE_QUARTERS_TURN), + Some(GateType::SY) + ); // theta=-pi/2 wraps to 3pi/2 assert_eq!( try_simplify_r1xy(-Angle64::QUARTER_TURN, Angle64::ZERO), diff --git a/crates/pecos-core/src/gate_type.rs b/crates/pecos-core/src/gate_type.rs index fe3a03de9..7a78555c6 100644 --- a/crates/pecos-core/src/gate_type.rs +++ b/crates/pecos-core/src/gate_type.rs @@ -108,6 +108,16 @@ pub enum GateType { /// Free/deallocate a qubit QFree = 136, Idle = 200, + /// Meta-gate: Pauli operator annotation for fault tracking. + /// + /// This gate carries a Pauli string but has no effect on quantum state. + /// Its position in the circuit determines which faults can flip the operator + /// (only faults before this node are relevant). The propagator uses it as a + /// backward propagation start point. + /// + /// The Pauli string is encoded in `params`: each param encodes + /// `qubit * 4 + pauli_type` where `pauli_type` is 1=X, 2=Y, 3=Z. + PauliOperatorMeta = 210, MeasCrosstalkGlobalPayload = 218, MeasCrosstalkLocalPayload = 219, /// Custom/unrecognized gate type, with actual name stored in metadata @@ -164,6 +174,7 @@ impl From for GateType { 200 => GateType::Idle, 218 => GateType::MeasCrosstalkGlobalPayload, 219 => GateType::MeasCrosstalkLocalPayload, + 210 => GateType::PauliOperatorMeta, 255 => GateType::Custom, _ => panic!("Invalid gate type ID: {value}"), } @@ -171,6 +182,15 @@ impl From for GateType { } impl GateType { + /// Returns true if this gate type is a meta-gate (annotation, not physical). + /// + /// Meta-gates have a position in the DAG but do not affect quantum state + /// and should not create fault locations or receive noise. + #[must_use] + pub const fn is_meta(self) -> bool { + matches!(self, GateType::PauliOperatorMeta) + } + /// Returns the number of angle parameters this gate type requires /// /// # Returns @@ -215,7 +235,8 @@ impl GateType { | GateType::PZ | GateType::QAlloc | GateType::QFree - | GateType::Custom => 0, + | GateType::Custom + | GateType::PauliOperatorMeta => 0, // Gates with one parameter GateType::RX @@ -277,7 +298,11 @@ impl GateType { | GateType::Idle | GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload - | GateType::Custom => 1, + | GateType::Custom + // PauliOperatorMeta is variable-arity but returns 1 here because + // gate validation checks `is_multiple_of(quantum_arity())` and any + // count is a multiple of 1. The actual qubit count is in the gate. + | GateType::PauliOperatorMeta => 1, // Two-qubit gates GateType::CX @@ -405,6 +430,7 @@ impl fmt::Display for GateType { GateType::MeasCrosstalkGlobalPayload => write!(f, "MeasCrosstalkGlobalPayload"), GateType::MeasCrosstalkLocalPayload => write!(f, "MeasCrosstalkLocalPayload"), GateType::Custom => write!(f, "Custom"), + GateType::PauliOperatorMeta => write!(f, "PauliOperator"), } } } diff --git a/crates/pecos-core/src/gates.rs b/crates/pecos-core/src/gates.rs index c48fa72a3..10cf991ca 100644 --- a/crates/pecos-core/src/gates.rs +++ b/crates/pecos-core/src/gates.rs @@ -4,6 +4,7 @@ //! gate operation with its type, qubits, and parameters. use crate::Angle64; +use crate::MeasId; use crate::QubitId; use crate::gate_type::GateType; use smallvec::SmallVec; @@ -20,6 +21,10 @@ pub type GateAngles = SmallVec<[Angle64; 3]>; /// Most gates have 0-1 non-angle parameters. pub type GateParams = SmallVec<[f64; 2]>; +/// Measurement result identities for measurement gates. +/// Empty for non-measurement gates. One entry per qubit for MZ/MX/MY. +pub type GateMeasIds = SmallVec<[MeasId; 1]>; + /// Flat gate command representation for quantum operations /// /// Clean, flat representation of quantum gate commands @@ -45,6 +50,12 @@ pub struct Gate { /// The qubits the gate acts on. /// Stack-allocated for up to 4 qubits. pub qubits: GateQubits, + /// Measurement result identities (one per qubit for measurement gates). + /// + /// Assigned at circuit construction time, carried through all + /// transformations. Empty for non-measurement gates. + /// Follows the MLIR SSA pattern: defined once, referenced everywhere. + pub meas_ids: GateMeasIds, } /// Legacy quantum gate representation for `ByteMessageBuilder` compatibility @@ -67,6 +78,7 @@ impl Gate { angles: angles.into(), params: params.into(), qubits: qubits.into(), + meas_ids: GateMeasIds::new(), } } diff --git a/crates/pecos-core/src/lib.rs b/crates/pecos-core/src/lib.rs index 7007492af..6a93a8eb9 100644 --- a/crates/pecos-core/src/lib.rs +++ b/crates/pecos-core/src/lib.rs @@ -30,6 +30,7 @@ pub mod index_set; pub mod pauli; pub mod phase; pub mod prelude; +pub mod meas_id; pub mod qubit_id; pub mod rng; pub mod sets; @@ -49,6 +50,7 @@ pub use index_set::IndexSet; pub use phase::GlobalPhase; pub use phase::quarter_phase::QuarterPhase; pub use phase::sign::Sign; +pub use meas_id::MeasId; pub use qubit_id::{QubitId, QubitIdSet, qid, qid2, qids, qids2}; pub use rng::{RngManageable, derive_seed}; pub use sets::set::Set; @@ -69,8 +71,12 @@ pub use gate_registry::{ AngleSource, ConcreteStep, DecompStep, GateDefinition, GateDefinitionBuilder, GateRegistry, GateSignature, }; -pub use gates::{Gate, GateAngles, GateParams, GateQubits}; +pub use gates::{Gate, GateAngles, GateMeasIds, GateParams, GateQubits}; pub use pauli::pauli_bitmap::PauliBitmap; +pub use pauli::pauli_bitmask::{ + BitmaskStorage, Conjugated, PauliBitmask, PauliBitmaskGeneric, PauliBitmaskSmall, + PauliBitmaskVec, +}; pub use pauli::pauli_sparse::PauliSparse; pub use pauli::pauli_string::{ParsePauliStringError, PauliString}; pub use pauli::{Pauli, PauliOperator}; diff --git a/crates/pecos-core/src/meas_id.rs b/crates/pecos-core/src/meas_id.rs new file mode 100644 index 000000000..e3ab6ea03 --- /dev/null +++ b/crates/pecos-core/src/meas_id.rs @@ -0,0 +1,68 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Measurement result identity. +//! +//! Each measurement gate (MZ, MX, etc.) produces a `MeasId` — a unique +//! identifier for that measurement's outcome. Assigned once at circuit +//! construction time, carried through all transformations (TickCircuit → +//! DagCircuit → InfluenceMap → DEM). Never reassigned. +//! +//! This follows the MLIR SSA pattern: the value is defined at one point +//! and referenced everywhere. Detectors reference `MeasId` values +//! directly instead of fragile position-dependent offsets. +//! +//! Metadata (qubit, basis, coordinates, labels) lives in a side table, +//! not on the `MeasId` itself. The hot path (DEM builder, sampler, +//! decoder) works with `MeasId` only. + +use std::fmt; + +/// Unique identity of a measurement result. +/// +/// Lightweight (pointer-sized), `Copy`, directly usable as an array index. +/// Analogous to [`QubitId`](crate::QubitId) but for measurement outcomes. +/// +/// # Example +/// +/// ``` +/// use pecos_core::MeasId; +/// +/// let m0 = MeasId(0); +/// let m1 = MeasId(1); +/// assert_ne!(m0, m1); +/// +/// // Direct array indexing +/// let mut outcomes = vec![false; 10]; +/// outcomes[m0.0] = true; +/// ``` +#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] +pub struct MeasId(pub usize); + +impl MeasId { + /// The underlying index. + #[inline] + #[must_use] + pub fn index(self) -> usize { + self.0 + } +} + +impl fmt::Display for MeasId { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "m{}", self.0) + } +} + +impl From for MeasId { + fn from(v: usize) -> Self { + Self(v) + } +} + +impl From for usize { + fn from(m: MeasId) -> Self { + m.0 + } +} diff --git a/crates/pecos-core/src/pauli.rs b/crates/pecos-core/src/pauli.rs index e18f21402..a20ef5976 100644 --- a/crates/pecos-core/src/pauli.rs +++ b/crates/pecos-core/src/pauli.rs @@ -16,6 +16,9 @@ pub mod constructors; #[allow(clippy::module_name_repetitions)] pub mod pauli_bitmap; +#[allow(clippy::module_name_repetitions)] +pub mod pauli_bitmask; + #[allow(clippy::module_name_repetitions)] pub mod pauli_sparse; diff --git a/crates/pecos-core/src/pauli/pauli_bitmask.rs b/crates/pecos-core/src/pauli/pauli_bitmask.rs new file mode 100644 index 000000000..2446bb280 --- /dev/null +++ b/crates/pecos-core/src/pauli/pauli_bitmask.rs @@ -0,0 +1,1036 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Compact Pauli operator using bitmasks with Clifford conjugation. +//! +//! Provides allocation-free Pauli arithmetic and Clifford conjugation +//! for use in error propagation, fault analysis, and EEG algorithms. +//! +//! The default `PauliBitmask` uses `u128` (up to 128 qubits). For +//! larger qubit counts, use `PauliBitmaskVec` which heap-allocates. + +use smallvec::SmallVec; +use std::fmt; + +/// Trait for bitmask storage backends. +/// +/// Enables `PauliBitmaskGeneric` to work with different widths: +/// `u64` (64 qubits), `u128` (128 qubits), or `Vec` (unlimited). +pub trait BitmaskStorage: + Clone + PartialEq + Eq + std::hash::Hash + Default + fmt::Debug +{ + fn zero() -> Self; + fn set_bit(&mut self, bit: usize); + fn clear_bit(&mut self, bit: usize); + fn get_bit(&self, bit: usize) -> bool; + fn xor_assign(&mut self, other: &Self); + fn xor_bit(&mut self, bit: usize); + fn and_count_ones_xor(&self, other_z: &Self, self_z: &Self, other_x: &Self) -> u32; + fn is_zero(&self) -> bool; + fn or_count_ones(&self, other: &Self) -> u32; + fn highest_set_bit(&self) -> Option; +} + +impl BitmaskStorage for u128 { + fn zero() -> Self { 0 } + fn set_bit(&mut self, bit: usize) { *self |= 1u128 << bit; } + fn clear_bit(&mut self, bit: usize) { *self &= !(1u128 << bit); } + fn get_bit(&self, bit: usize) -> bool { *self & (1u128 << bit) != 0 } + fn xor_assign(&mut self, other: &Self) { *self ^= other; } + fn xor_bit(&mut self, bit: usize) { *self ^= 1u128 << bit; } + fn and_count_ones_xor(&self, other_z: &Self, self_z: &Self, other_x: &Self) -> u32 { + ((*self & other_z) ^ (self_z & other_x)).count_ones() + } + fn is_zero(&self) -> bool { *self == 0 } + fn or_count_ones(&self, other: &Self) -> u32 { (*self | other).count_ones() } + fn highest_set_bit(&self) -> Option { + if *self == 0 { None } else { Some(127 - self.leading_zeros() as usize) } + } +} + +impl BitmaskStorage for Vec { + fn zero() -> Self { Vec::new() } + fn set_bit(&mut self, bit: usize) { + let word = bit / 64; + if word >= self.len() { self.resize(word + 1, 0); } + self[word] |= 1u64 << (bit % 64); + } + fn clear_bit(&mut self, bit: usize) { + let word = bit / 64; + if word < self.len() { self[word] &= !(1u64 << (bit % 64)); } + } + fn get_bit(&self, bit: usize) -> bool { + let word = bit / 64; + word < self.len() && self[word] & (1u64 << (bit % 64)) != 0 + } + fn xor_assign(&mut self, other: &Self) { + if self.len() < other.len() { self.resize(other.len(), 0); } + for (a, b) in self.iter_mut().zip(other.iter()) { *a ^= b; } + } + fn xor_bit(&mut self, bit: usize) { + let word = bit / 64; + if word >= self.len() { self.resize(word + 1, 0); } + self[word] ^= 1u64 << (bit % 64); + } + fn and_count_ones_xor(&self, other_z: &Self, self_z: &Self, other_x: &Self) -> u32 { + let max = self.len().max(other_z.len()).max(self_z.len()).max(other_x.len()); + let mut count = 0u32; + for i in 0..max { + let sx = self.get(i).copied().unwrap_or(0); + let oz = other_z.get(i).copied().unwrap_or(0); + let sz = self_z.get(i).copied().unwrap_or(0); + let ox = other_x.get(i).copied().unwrap_or(0); + count += ((sx & oz) ^ (sz & ox)).count_ones(); + } + count + } + fn is_zero(&self) -> bool { self.iter().all(|&w| w == 0) } + fn or_count_ones(&self, other: &Self) -> u32 { + let max = self.len().max(other.len()); + let mut count = 0u32; + for i in 0..max { + let a = self.get(i).copied().unwrap_or(0); + let b = other.get(i).copied().unwrap_or(0); + count += (a | b).count_ones(); + } + count + } + fn highest_set_bit(&self) -> Option { + for (i, &w) in self.iter().enumerate().rev() { + if w != 0 { return Some(i * 64 + 63 - w.leading_zeros() as usize); } + } + None + } +} + +/// SmallVec<[u64; 8]> backend: 512 bits inline (covers d≤9 surface codes), +/// spills to heap for larger circuits. Zero allocation for typical QEC. +impl BitmaskStorage for SmallVec<[u64; 8]> { + fn zero() -> Self { SmallVec::new() } + fn set_bit(&mut self, bit: usize) { + let word = bit / 64; + if word >= self.len() { self.resize(word + 1, 0); } + self[word] |= 1u64 << (bit % 64); + } + fn clear_bit(&mut self, bit: usize) { + let word = bit / 64; + if word < self.len() { self[word] &= !(1u64 << (bit % 64)); } + } + fn get_bit(&self, bit: usize) -> bool { + let word = bit / 64; + word < self.len() && self[word] & (1u64 << (bit % 64)) != 0 + } + fn xor_assign(&mut self, other: &Self) { + if self.len() < other.len() { self.resize(other.len(), 0); } + for (a, b) in self.iter_mut().zip(other.iter()) { *a ^= b; } + } + fn xor_bit(&mut self, bit: usize) { + let word = bit / 64; + if word >= self.len() { self.resize(word + 1, 0); } + self[word] ^= 1u64 << (bit % 64); + } + fn and_count_ones_xor(&self, other_z: &Self, self_z: &Self, other_x: &Self) -> u32 { + let max = self.len().max(other_z.len()).max(self_z.len()).max(other_x.len()); + let mut count = 0u32; + for i in 0..max { + let sx = self.get(i).copied().unwrap_or(0); + let oz = other_z.get(i).copied().unwrap_or(0); + let sz = self_z.get(i).copied().unwrap_or(0); + let ox = other_x.get(i).copied().unwrap_or(0); + count += ((sx & oz) ^ (sz & ox)).count_ones(); + } + count + } + fn is_zero(&self) -> bool { self.iter().all(|&w| w == 0) } + fn or_count_ones(&self, other: &Self) -> u32 { + let max = self.len().max(other.len()); + let mut count = 0u32; + for i in 0..max { + let a = self.get(i).copied().unwrap_or(0); + let b = other.get(i).copied().unwrap_or(0); + count += (a | b).count_ones(); + } + count + } + fn highest_set_bit(&self) -> Option { + for (i, &w) in self.iter().enumerate().rev() { + if w != 0 { return Some(i * 64 + 63 - w.leading_zeros() as usize); } + } + None + } +} + +/// N-qubit Pauli operator in symplectic binary representation. +/// +/// Phase is NOT tracked internally — the caller tracks signs from +/// multiplication and conjugation separately. +/// +/// Type parameter `B` selects the bitmask backend: +/// - `u128` (default): up to 128 qubits, stack-allocated, `Copy` +/// - `Vec`: unlimited qubits, heap-allocated +#[derive(Clone, Default)] +pub struct PauliBitmaskGeneric { + pub x_bits: B, + pub z_bits: B, +} + +// --- PartialEq, Eq, Hash for u128 backend --- + +impl PartialEq for PauliBitmaskGeneric { + fn eq(&self, other: &Self) -> bool { + self.x_bits == other.x_bits && self.z_bits == other.z_bits + } +} + +impl Eq for PauliBitmaskGeneric {} + +impl std::hash::Hash for PauliBitmaskGeneric { + fn hash(&self, state: &mut H) { + self.x_bits.hash(state); + self.z_bits.hash(state); + } +} + +// --- PartialEq, Eq, Hash for Vec backend --- +// Trailing zero words are ignored so that Vecs of different lengths +// representing the same logical value compare equal and hash identically. + +impl PartialEq for PauliBitmaskGeneric> { + fn eq(&self, other: &Self) -> bool { + vecs_eq_ignoring_trailing_zeros(&self.x_bits, &other.x_bits) + && vecs_eq_ignoring_trailing_zeros(&self.z_bits, &other.z_bits) + } +} + +impl Eq for PauliBitmaskGeneric> {} + +impl std::hash::Hash for PauliBitmaskGeneric> { + fn hash(&self, state: &mut H) { + hash_vec_ignoring_trailing_zeros(&self.x_bits, state); + hash_vec_ignoring_trailing_zeros(&self.z_bits, state); + } +} + +fn vecs_eq_ignoring_trailing_zeros(a: &[u64], b: &[u64]) -> bool { + let max = a.len().max(b.len()); + for i in 0..max { + let aw = a.get(i).copied().unwrap_or(0); + let bw = b.get(i).copied().unwrap_or(0); + if aw != bw { + return false; + } + } + true +} + +fn hash_vec_ignoring_trailing_zeros(v: &[u64], state: &mut H) { + use std::hash::Hash; + // Find the last non-zero word and hash only up to that point. + let effective_len = v.iter().rposition(|&w| w != 0).map_or(0, |i| i + 1); + effective_len.hash(state); + for &w in &v[..effective_len] { + w.hash(state); + } +} + +/// Fixed-size Pauli bitmask for up to 128 qubits (stack-allocated, Copy). +pub type PauliBitmask = PauliBitmaskGeneric; + +/// Dynamically-sized Pauli bitmask for unlimited qubits (heap-allocated). +pub type PauliBitmaskVec = PauliBitmaskGeneric>; + +/// SmallVec-backed Pauli bitmask: 512 bits inline (d≤9 surface codes), +/// spills to heap only for larger circuits. Best of both worlds. +pub type PauliBitmaskSmall = PauliBitmaskGeneric>; + +// --- PartialEq, Eq, Hash, Ord for SmallVec backend --- + +impl PartialEq for PauliBitmaskSmall { + fn eq(&self, other: &Self) -> bool { + vecs_eq_ignoring_trailing_zeros(&self.x_bits, &other.x_bits) + && vecs_eq_ignoring_trailing_zeros(&self.z_bits, &other.z_bits) + } +} + +impl Eq for PauliBitmaskSmall {} + +impl std::hash::Hash for PauliBitmaskSmall { + fn hash(&self, state: &mut H) { + hash_vec_ignoring_trailing_zeros(&self.x_bits, state); + hash_vec_ignoring_trailing_zeros(&self.z_bits, state); + } +} + +impl PartialOrd for PauliBitmaskSmall { + fn partial_cmp(&self, other: &Self) -> Option { Some(self.cmp(other)) } +} + +impl Ord for PauliBitmaskSmall { + fn cmp(&self, other: &Self) -> std::cmp::Ordering { + let max_len = self.x_bits.len().max(other.x_bits.len()) + .max(self.z_bits.len()).max(other.z_bits.len()); + for i in (0..max_len).rev() { + let sx = self.x_bits.get(i).copied().unwrap_or(0); + let ox = other.x_bits.get(i).copied().unwrap_or(0); + match sx.cmp(&ox) { + std::cmp::Ordering::Equal => {} + ord => return ord, + } + } + for i in (0..max_len).rev() { + let sz = self.z_bits.get(i).copied().unwrap_or(0); + let oz = other.z_bits.get(i).copied().unwrap_or(0); + match sz.cmp(&oz) { + std::cmp::Ordering::Equal => {} + ord => return ord, + } + } + std::cmp::Ordering::Equal + } +} + +// Copy only for fixed-size backends +impl Copy for PauliBitmask {} +impl PartialOrd for PauliBitmask { + fn partial_cmp(&self, other: &Self) -> Option { Some(self.cmp(other)) } +} +impl Ord for PauliBitmask { + fn cmp(&self, other: &Self) -> std::cmp::Ordering { + self.x_bits.cmp(&other.x_bits).then(self.z_bits.cmp(&other.z_bits)) + } +} + +impl PartialOrd for PauliBitmaskVec { + fn partial_cmp(&self, other: &Self) -> Option { Some(self.cmp(other)) } +} +impl Ord for PauliBitmaskVec { + fn cmp(&self, other: &Self) -> std::cmp::Ordering { + // Lexicographic comparison of the word vectors (most-significant word first) + let max_len = self.x_bits.len().max(other.x_bits.len()) + .max(self.z_bits.len()).max(other.z_bits.len()); + for i in (0..max_len).rev() { + let sx = self.x_bits.get(i).copied().unwrap_or(0); + let ox = other.x_bits.get(i).copied().unwrap_or(0); + match sx.cmp(&ox) { + std::cmp::Ordering::Equal => {} + ord => return ord, + } + } + for i in (0..max_len).rev() { + let sz = self.z_bits.get(i).copied().unwrap_or(0); + let oz = other.z_bits.get(i).copied().unwrap_or(0); + match sz.cmp(&oz) { + std::cmp::Ordering::Equal => {} + ord => return ord, + } + } + std::cmp::Ordering::Equal + } +} + +impl PauliBitmaskGeneric { + /// Single-qubit X on qubit q. + #[must_use] + pub fn x(q: usize) -> Self { + let mut x = B::zero(); + x.set_bit(q); + Self { x_bits: x, z_bits: B::zero() } + } + + /// Single-qubit Z on qubit q. + #[must_use] + pub fn z(q: usize) -> Self { + let mut z = B::zero(); + z.set_bit(q); + Self { x_bits: B::zero(), z_bits: z } + } + + /// Single-qubit Y on qubit q. + #[must_use] + pub fn y(q: usize) -> Self { + let mut x = B::zero(); + let mut z = B::zero(); + x.set_bit(q); + z.set_bit(q); + Self { x_bits: x, z_bits: z } + } + + /// Product of two Pauli labels (XOR of symplectic vectors, phase ignored). + #[must_use] + pub fn multiply(&self, other: &Self) -> Self { + let mut x = self.x_bits.clone(); + x.xor_assign(&other.x_bits); + let mut z = self.z_bits.clone(); + z.xor_assign(&other.z_bits); + Self { x_bits: x, z_bits: z } + } + + /// Product of two Paulis with phase tracking. + /// + /// Returns (product, phase_exponent) where the full product is i^phase · product. + /// Phase exponent is in 0..4. + #[must_use] + pub fn multiply_with_phase(&self, other: &Self) -> (Self, u8) { + let product = self.multiply(other); + + // Per-qubit phase from Pauli multiplication. + // Pauli types: I=0, X=1, Z=2, Y=3 (encoding: type = x + 2*z) + // Phase lookup: A*B = i^{phase[A][B]} * C + // I X Z Y + // 0 0 0 0 (I * anything) + // 0 0 3 1 (X * I,X,Z,Y) + // 0 1 0 3 (Z * I,X,Z,Y) + // 0 3 1 0 (Y * I,X,Z,Y) + const PHASE_TABLE: [[u8; 4]; 4] = [ + [0, 0, 0, 0], // I + [0, 0, 3, 1], // X + [0, 1, 0, 3], // Z + [0, 3, 1, 0], // Y + ]; + + let mut total_phase = 0u32; + let max_q = match self.x_bits.highest_set_bit() { + Some(a) => { + let b = other.x_bits.highest_set_bit().unwrap_or(0); + let c = self.z_bits.highest_set_bit().unwrap_or(0); + let d = other.z_bits.highest_set_bit().unwrap_or(0); + a.max(b).max(c).max(d) + 1 + } + None => match other.x_bits.highest_set_bit() { + Some(b) => { + let c = self.z_bits.highest_set_bit().unwrap_or(0); + let d = other.z_bits.highest_set_bit().unwrap_or(0); + b.max(c).max(d) + 1 + } + None => { + let c = self.z_bits.highest_set_bit().unwrap_or(0); + let d = other.z_bits.highest_set_bit().unwrap_or(0); + if c == 0 && d == 0 && self.z_bits.is_zero() && other.z_bits.is_zero() { + 0 + } else { + c.max(d) + 1 + } + } + }, + }; + + for q in 0..max_q { + let xa = self.x_bits.get_bit(q) as usize; + let za = self.z_bits.get_bit(q) as usize; + let xb = other.x_bits.get_bit(q) as usize; + let zb = other.z_bits.get_bit(q) as usize; + let type_a = xa + 2 * za; // I=0, X=1, Z=2, Y=3 + let type_b = xb + 2 * zb; + total_phase += u32::from(PHASE_TABLE[type_a][type_b]); + } + + (product, (total_phase % 4) as u8) + } + + /// True if the two Paulis commute (symplectic inner product = 0 mod 2). + #[must_use] + pub fn commutes_with(&self, other: &Self) -> bool { + self.x_bits + .and_count_ones_xor(&other.z_bits, &self.z_bits, &other.x_bits) + % 2 + == 0 + } + + #[must_use] + pub fn is_identity(&self) -> bool { + self.x_bits.is_zero() && self.z_bits.is_zero() + } + + /// Number of non-identity single-qubit factors. + #[must_use] + pub fn weight(&self) -> u32 { + self.x_bits.or_count_ones(&self.z_bits) + } + + #[must_use] + pub fn has_x(&self, q: usize) -> bool { + self.x_bits.get_bit(q) + } + + #[must_use] + pub fn has_z(&self, q: usize) -> bool { + self.z_bits.get_bit(q) + } +} + +impl PauliBitmask { + pub const IDENTITY: Self = Self { x_bits: 0, z_bits: 0 }; +} + +impl PauliBitmaskGeneric { + /// Identity Pauli (all qubits I). + #[must_use] + pub fn identity() -> Self { + Self { x_bits: B::zero(), z_bits: B::zero() } + } +} + +/// Convert from u128 (fixed-size) to Vec (unlimited) backend. +impl From for PauliBitmaskVec { + fn from(p: PauliBitmask) -> Self { + let x_lo = p.x_bits as u64; + let x_hi = (p.x_bits >> 64) as u64; + let z_lo = p.z_bits as u64; + let z_hi = (p.z_bits >> 64) as u64; + Self { + x_bits: if x_hi != 0 { vec![x_lo, x_hi] } else if x_lo != 0 { vec![x_lo] } else { vec![] }, + z_bits: if z_hi != 0 { vec![z_lo, z_hi] } else if z_lo != 0 { vec![z_lo] } else { vec![] }, + } + } +} + +impl From for PauliBitmaskSmall { + fn from(p: PauliBitmask) -> Self { + let x_lo = p.x_bits as u64; + let x_hi = (p.x_bits >> 64) as u64; + let z_lo = p.z_bits as u64; + let z_hi = (p.z_bits >> 64) as u64; + let mut x = SmallVec::new(); + if x_hi != 0 { x.push(x_lo); x.push(x_hi); } + else if x_lo != 0 { x.push(x_lo); } + let mut z = SmallVec::new(); + if z_hi != 0 { z.push(z_lo); z.push(z_hi); } + else if z_lo != 0 { z.push(z_lo); } + Self { x_bits: x, z_bits: z } + } +} + +impl fmt::Debug for PauliBitmaskGeneric { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + if self.is_identity() { + return write!(f, "I"); + } + let max_q = match self.x_bits.highest_set_bit() { + Some(a) => match self.z_bits.highest_set_bit() { + Some(b) => a.max(b) + 1, + None => a + 1, + }, + None => match self.z_bits.highest_set_bit() { + Some(b) => b + 1, + None => return write!(f, "I"), + }, + }; + for q in 0..max_q { + match (self.has_x(q), self.has_z(q)) { + (false, false) => write!(f, "I")?, + (true, false) => write!(f, "X")?, + (false, true) => write!(f, "Z")?, + (true, true) => write!(f, "Y")?, + } + } + Ok(()) + } +} + +// ============================================================ +// Clifford conjugation: U†PU = sign * P' +// ============================================================ + +/// Result of Clifford conjugation U†PU. +#[derive(Clone, Debug)] +pub struct Conjugated { + pub label: PauliBitmaskGeneric, + /// True if the sign is negative (U†PU = -P'). + pub sign_negative: bool, +} + +impl Copy for Conjugated {} + +/// Hadamard on qubit q: X↔Z, Y→-Y. +#[must_use] +pub fn conjugate_h(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + let has_x = p.x_bits.get_bit(q); + let has_z = p.z_bits.get_bit(q); + let mut label = p.clone(); + if has_x != has_z { + label.x_bits.xor_bit(q); + label.z_bits.xor_bit(q); + } + Conjugated { label, sign_negative: has_x && has_z } +} + +/// SZ gate on qubit q: X→Y, Y→-X, Z→Z. +#[must_use] +pub fn conjugate_sz(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + if !p.x_bits.get_bit(q) { + return Conjugated { label: p.clone(), sign_negative: false }; + } + let was_y = p.z_bits.get_bit(q); + let mut label = p.clone(); + label.z_bits.xor_bit(q); + Conjugated { label, sign_negative: was_y } +} + +/// SZdg gate on qubit q: X→-Y, Y→X, Z→Z. +#[must_use] +pub fn conjugate_szdg(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + if !p.x_bits.get_bit(q) { + return Conjugated { label: p.clone(), sign_negative: false }; + } + let was_y = p.z_bits.get_bit(q); + let mut label = p.clone(); + label.z_bits.xor_bit(q); + Conjugated { label, sign_negative: !was_y } +} + +/// CX (CNOT) with control c, target t: XI→XX, IZ→ZZ. +/// +/// The sign comes from Pauli multiplication phases when the control's +/// Pauli multiplies Z (from target Z spreading) and the target's Pauli +/// multiplies X (from control X spreading): +/// phase_c = phase(Pc · Z) if target has Z, else 0 +/// phase_t = phase(X · Pt) if control has X, else 0 +/// sign_negative = (phase_c + phase_t) % 4 == 2 +#[must_use] +pub fn conjugate_cx(p: &PauliBitmaskGeneric, c: usize, t: usize) -> Conjugated { + let cx = p.x_bits.get_bit(c); + let cz = p.z_bits.get_bit(c); + let tx = p.x_bits.get_bit(t); + let tz = p.z_bits.get_bit(t); + let mut label = p.clone(); + if cx { label.x_bits.xor_bit(t); } + if tz { label.z_bits.xor_bit(c); } + // Pauli type encoding: I=0, X=1, Z=2, Y=3 (x + 2*z) + // Phase from Pauli multiplication table: + // Pc·Z at control (if tz), X·Pt at target (if cx) + const PHASE: [[u8; 4]; 4] = [ + [0, 0, 0, 0], // I·{I,X,Z,Y} + [0, 0, 3, 1], // X·{I,X,Z,Y} + [0, 1, 0, 3], // Z·{I,X,Z,Y} + [0, 3, 1, 0], // Y·{I,X,Z,Y} + ]; + let pc = (cx as u8) + 2 * (cz as u8); + let pt = (tx as u8) + 2 * (tz as u8); + let phase_c = if tz { PHASE[pc as usize][2] } else { 0 }; + let phase_t = if cx { PHASE[1][pt as usize] } else { 0 }; + Conjugated { label, sign_negative: (phase_c + phase_t) % 4 == 2 } +} + +/// CZ on qubits a, b: XI→XZ, IX→ZX, ZI→ZI, IZ→IZ. +#[must_use] +pub fn conjugate_cz(p: &PauliBitmaskGeneric, a: usize, b: usize) -> Conjugated { + let ax = p.x_bits.get_bit(a); + let az = p.z_bits.get_bit(a); + let bx = p.x_bits.get_bit(b); + let bz = p.z_bits.get_bit(b); + let mut label = p.clone(); + if bx { label.z_bits.xor_bit(a); } + if ax { label.z_bits.xor_bit(b); } + Conjugated { label, sign_negative: ax && bx && (az != bz) } +} + +/// Pauli X gate on qubit q: Z→-Z, Y→-Y. +#[must_use] +pub fn conjugate_x(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + Conjugated { label: p.clone(), sign_negative: p.z_bits.get_bit(q) } +} + +/// Pauli Y gate on qubit q: X→-X, Z→-Z. +#[must_use] +pub fn conjugate_y(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + Conjugated { + label: p.clone(), + sign_negative: p.x_bits.get_bit(q) != p.z_bits.get_bit(q), + } +} + +/// Pauli Z gate on qubit q: X→-X, Y→-Y. +#[must_use] +pub fn conjugate_z(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + Conjugated { label: p.clone(), sign_negative: p.x_bits.get_bit(q) } +} + +/// SWAP on qubits a, b: exchanges the Pauli at both sites. +#[must_use] +pub fn conjugate_swap(p: &PauliBitmaskGeneric, a: usize, b: usize) -> Conjugated { + let ax = p.x_bits.get_bit(a); + let az = p.z_bits.get_bit(a); + let bx = p.x_bits.get_bit(b); + let bz = p.z_bits.get_bit(b); + let mut label = p.clone(); + // Clear both positions + if ax { label.x_bits.clear_bit(a); } else { label.x_bits.clear_bit(a); } + if bx { label.x_bits.clear_bit(b); } else { label.x_bits.clear_bit(b); } + if az { label.z_bits.clear_bit(a); } + if bz { label.z_bits.clear_bit(b); } + // Set swapped + if bx { label.x_bits.set_bit(a); } + if ax { label.x_bits.set_bit(b); } + if bz { label.z_bits.set_bit(a); } + if az { label.z_bits.set_bit(b); } + Conjugated { label, sign_negative: false } +} + +/// SX gate on qubit q: X→X, Z→-Y, Y→Z. +#[must_use] +pub fn conjugate_sx(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + let xq = p.x_bits.get_bit(q); + let zq = p.z_bits.get_bit(q); + let mut label = p.clone(); + if zq { label.x_bits.xor_bit(q); } + Conjugated { label, sign_negative: !xq && zq } +} + +/// SXdg gate on qubit q: X→X, Z→Y, Y→-Z. +#[must_use] +pub fn conjugate_sxdg(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + let xq = p.x_bits.get_bit(q); + let zq = p.z_bits.get_bit(q); + let mut label = p.clone(); + if zq { label.x_bits.xor_bit(q); } + Conjugated { label, sign_negative: xq && zq } +} + +/// SY gate on qubit q: X→-Z, Y→Y, Z→X. +#[must_use] +pub fn conjugate_sy(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + let xq = p.x_bits.get_bit(q); + let zq = p.z_bits.get_bit(q); + let mut label = p.clone(); + if xq != zq { + label.x_bits.xor_bit(q); + label.z_bits.xor_bit(q); + } + Conjugated { label, sign_negative: xq && !zq } +} + +/// SYdg gate on qubit q: X→Z, Y→Y, Z→-X. +#[must_use] +pub fn conjugate_sydg(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + let xq = p.x_bits.get_bit(q); + let zq = p.z_bits.get_bit(q); + let mut label = p.clone(); + if xq != zq { + label.x_bits.xor_bit(q); + label.z_bits.xor_bit(q); + } + Conjugated { label, sign_negative: !xq && zq } +} + +/// CY (controlled-Y) with control c, target t. +/// +/// Decomposed as CY = (I⊗SZ) · CX · (I⊗SZdg), so conjugation is: +/// 1. conjugate by SZdg on target +/// 2. conjugate by CX +/// 3. conjugate by SZ on target +#[must_use] +pub fn conjugate_cy(p: &PauliBitmaskGeneric, c: usize, t: usize) -> Conjugated { + let r1 = conjugate_szdg(p, t); + let r2 = conjugate_cx(&r1.label, c, t); + let r3 = conjugate_sz(&r2.label, t); + Conjugated { + label: r3.label, + sign_negative: r1.sign_negative ^ r2.sign_negative ^ r3.sign_negative, + } +} + +#[cfg(test)] +mod tests { + use super::*; + + // --- PauliBitmask basics --- + + #[test] + fn test_commutation() { + assert!(!PauliBitmask::x(0).commutes_with(&PauliBitmask::z(0))); + assert!(PauliBitmask::x(0).commutes_with(&PauliBitmask::x(1))); + assert!(!PauliBitmask::x(0).commutes_with(&PauliBitmask::y(0))); + + let a = PauliBitmask { x_bits: 1, z_bits: 2 }; + let b = PauliBitmask { x_bits: 2, z_bits: 1 }; + assert!(a.commutes_with(&b)); + } + + #[test] + fn test_multiply() { + assert_eq!(PauliBitmask::x(0).multiply(&PauliBitmask::z(0)), PauliBitmask::y(0)); + } + + #[test] + fn test_h() { + let r = conjugate_h(&PauliBitmask::x(0), 0); + assert_eq!(r.label, PauliBitmask::z(0)); + assert!(!r.sign_negative); + + let r = conjugate_h(&PauliBitmask::z(0), 0); + assert_eq!(r.label, PauliBitmask::x(0)); + assert!(!r.sign_negative); + + let r = conjugate_h(&PauliBitmask::y(0), 0); + assert_eq!(r.label, PauliBitmask::y(0)); + assert!(r.sign_negative); + } + + #[test] + fn test_sz() { + let r = conjugate_sz(&PauliBitmask::x(0), 0); + assert_eq!(r.label, PauliBitmask::y(0)); + assert!(!r.sign_negative); + + let r = conjugate_sz(&PauliBitmask::y(0), 0); + assert_eq!(r.label, PauliBitmask::x(0)); + assert!(r.sign_negative); + + let r = conjugate_sz(&PauliBitmask::z(0), 0); + assert_eq!(r.label, PauliBitmask::z(0)); + assert!(!r.sign_negative); + } + + #[test] + fn test_szdg() { + let r = conjugate_szdg(&PauliBitmask::x(0), 0); + assert_eq!(r.label, PauliBitmask::y(0)); + assert!(r.sign_negative); + + let r = conjugate_szdg(&PauliBitmask::y(0), 0); + assert_eq!(r.label, PauliBitmask::x(0)); + assert!(!r.sign_negative); + } + + #[test] + fn test_cx() { + let r = conjugate_cx(&PauliBitmask::x(0), 0, 1); + assert_eq!(r.label, PauliBitmask { x_bits: 0b11, z_bits: 0 }); + assert!(!r.sign_negative); + + let r = conjugate_cx(&PauliBitmask::z(1), 0, 1); + assert_eq!(r.label, PauliBitmask { x_bits: 0, z_bits: 0b11 }); + assert!(!r.sign_negative); + + let r = conjugate_cx(&PauliBitmask::x(1), 0, 1); + assert_eq!(r.label, PauliBitmask::x(1)); + assert!(!r.sign_negative); + } + + #[test] + fn test_cz() { + let r = conjugate_cz(&PauliBitmask::x(0), 0, 1); + assert_eq!(r.label, PauliBitmask { x_bits: 1, z_bits: 2 }); + assert!(!r.sign_negative); + + let r = conjugate_cz(&PauliBitmask::z(0), 0, 1); + assert_eq!(r.label, PauliBitmask::z(0)); + assert!(!r.sign_negative); + } + + #[test] + fn test_swap() { + let r = conjugate_swap(&PauliBitmask::x(0), 0, 1); + assert_eq!(r.label, PauliBitmask::x(1)); + assert!(!r.sign_negative); + } + + #[test] + fn test_h_involution() { + for p in [PauliBitmask::x(0), PauliBitmask::z(0), PauliBitmask::y(0)] { + let r1 = conjugate_h(&p, 0); + let r2 = conjugate_h(&r1.label, 0); + assert_eq!(r2.label, p); + assert!(!(r1.sign_negative ^ r2.sign_negative)); + } + } + + #[test] + fn test_sz_fourth_power() { + let p = PauliBitmask::x(0); + let mut label = p; + let mut sign = false; + for _ in 0..4 { + let r = conjugate_sz(&label, 0); + label = r.label; + sign ^= r.sign_negative; + } + assert_eq!(label, p); + assert!(!sign); + } + + #[test] + fn test_sx() { + // X→X (no sign) + let r = conjugate_sx(&PauliBitmask::x(0), 0); + assert_eq!(r.label, PauliBitmask::x(0)); + assert!(!r.sign_negative); + + // Z→-Y + let r = conjugate_sx(&PauliBitmask::z(0), 0); + assert_eq!(r.label, PauliBitmask::y(0)); + assert!(r.sign_negative); + + // Y→Z (no sign) + let r = conjugate_sx(&PauliBitmask::y(0), 0); + assert_eq!(r.label, PauliBitmask::z(0)); + assert!(!r.sign_negative); + } + + #[test] + fn test_sxdg() { + // X→X + let r = conjugate_sxdg(&PauliBitmask::x(0), 0); + assert_eq!(r.label, PauliBitmask::x(0)); + assert!(!r.sign_negative); + + // Z→Y + let r = conjugate_sxdg(&PauliBitmask::z(0), 0); + assert_eq!(r.label, PauliBitmask::y(0)); + assert!(!r.sign_negative); + + // Y→-Z + let r = conjugate_sxdg(&PauliBitmask::y(0), 0); + assert_eq!(r.label, PauliBitmask::z(0)); + assert!(r.sign_negative); + } + + #[test] + fn test_sy() { + // X→-Z + let r = conjugate_sy(&PauliBitmask::x(0), 0); + assert_eq!(r.label, PauliBitmask::z(0)); + assert!(r.sign_negative); + + // Z→X + let r = conjugate_sy(&PauliBitmask::z(0), 0); + assert_eq!(r.label, PauliBitmask::x(0)); + assert!(!r.sign_negative); + + // Y→Y + let r = conjugate_sy(&PauliBitmask::y(0), 0); + assert_eq!(r.label, PauliBitmask::y(0)); + assert!(!r.sign_negative); + } + + #[test] + fn test_sydg() { + // X→Z + let r = conjugate_sydg(&PauliBitmask::x(0), 0); + assert_eq!(r.label, PauliBitmask::z(0)); + assert!(!r.sign_negative); + + // Z→-X + let r = conjugate_sydg(&PauliBitmask::z(0), 0); + assert_eq!(r.label, PauliBitmask::x(0)); + assert!(r.sign_negative); + + // Y→Y + let r = conjugate_sydg(&PauliBitmask::y(0), 0); + assert_eq!(r.label, PauliBitmask::y(0)); + assert!(!r.sign_negative); + } + + #[test] + fn test_sx_fourth_power() { + let p = PauliBitmask::z(0); + let mut label = p; + let mut sign = false; + for _ in 0..4 { + let r = conjugate_sx(&label, 0); + label = r.label; + sign ^= r.sign_negative; + } + assert_eq!(label, p); + assert!(!sign); + } + + #[test] + fn test_sy_fourth_power() { + let p = PauliBitmask::x(0); + let mut label = p; + let mut sign = false; + for _ in 0..4 { + let r = conjugate_sy(&label, 0); + label = r.label; + sign ^= r.sign_negative; + } + assert_eq!(label, p); + assert!(!sign); + } + + #[test] + fn test_sx_sxdg_inverse() { + for p in [PauliBitmask::x(0), PauliBitmask::z(0), PauliBitmask::y(0)] { + let r1 = conjugate_sx(&p, 0); + let r2 = conjugate_sxdg(&r1.label, 0); + assert_eq!(r2.label, p); + assert!(!(r1.sign_negative ^ r2.sign_negative)); + } + } + + #[test] + fn test_sy_sydg_inverse() { + for p in [PauliBitmask::x(0), PauliBitmask::z(0), PauliBitmask::y(0)] { + let r1 = conjugate_sy(&p, 0); + let r2 = conjugate_sydg(&r1.label, 0); + assert_eq!(r2.label, p); + assert!(!(r1.sign_negative ^ r2.sign_negative)); + } + } + + #[test] + fn test_cy() { + // X_c → X_c Y_t + let r = conjugate_cy(&PauliBitmask::x(0), 0, 1); + assert_eq!(r.label, PauliBitmask { x_bits: 0b11, z_bits: 0b10 }); + assert!(!r.sign_negative); + + // Z_c → Z_c + let r = conjugate_cy(&PauliBitmask::z(0), 0, 1); + assert_eq!(r.label, PauliBitmask::z(0)); + assert!(!r.sign_negative); + + // X_t → Z_c X_t + let r = conjugate_cy(&PauliBitmask::x(1), 0, 1); + assert_eq!(r.label, PauliBitmask { x_bits: 0b10, z_bits: 0b01 }); + assert!(!r.sign_negative); + + // Z_t → Z_c Z_t + let r = conjugate_cy(&PauliBitmask::z(1), 0, 1); + assert_eq!(r.label, PauliBitmask { x_bits: 0, z_bits: 0b11 }); + assert!(!r.sign_negative); + } + + #[test] + fn test_multiply_with_phase() { + // X * Z = -iY (phase = 3, i.e., i^3 = -i) + let (prod, phase) = PauliBitmask::x(0).multiply_with_phase(&PauliBitmask::z(0)); + assert_eq!(prod, PauliBitmask::y(0)); + assert_eq!(phase, 3); // i^3 = -i + + // Z * X = iY (phase = 1) + let (prod, phase) = PauliBitmask::z(0).multiply_with_phase(&PauliBitmask::x(0)); + assert_eq!(prod, PauliBitmask::y(0)); + assert_eq!(phase, 1); // i^1 = i + + // X * X = I (phase = 0) + let (prod, phase) = PauliBitmask::x(0).multiply_with_phase(&PauliBitmask::x(0)); + assert!(prod.is_identity()); + assert_eq!(phase, 0); + + // Y * Y = I (phase = 0) + let (prod, phase) = PauliBitmask::y(0).multiply_with_phase(&PauliBitmask::y(0)); + assert!(prod.is_identity()); + assert_eq!(phase, 0); + + // Multi-qubit: (X⊗Z) * (Z⊗X) = (XZ)⊗(ZX) = (-iY)⊗(iY) = (-i·i)(Y⊗Y) = Y⊗Y + let a = PauliBitmask { x_bits: 0b01, z_bits: 0b10 }; // XZ + let b = PauliBitmask { x_bits: 0b10, z_bits: 0b01 }; // ZX + let (prod, phase) = a.multiply_with_phase(&b); + assert_eq!(prod, PauliBitmask { x_bits: 0b11, z_bits: 0b11 }); // YY + assert_eq!(phase, 0); // (-i)(i) = 1, phase = 3+1 = 4 mod 4 = 0 + } + + #[test] + fn test_cy_involution() { + // CY is hermitian (CY² = I), so double conjugation should be identity + for p in [PauliBitmask::x(0), PauliBitmask::z(0), PauliBitmask::x(1), PauliBitmask::z(1)] { + let r1 = conjugate_cy(&p, 0, 1); + let r2 = conjugate_cy(&r1.label, 0, 1); + assert_eq!(r2.label, p); + assert!(!(r1.sign_negative ^ r2.sign_negative)); + } + } +} diff --git a/crates/pecos-cppsparsestab/src/lib.rs b/crates/pecos-cppsparsestab/src/lib.rs index 149d30029..fd9587866 100644 --- a/crates/pecos-cppsparsestab/src/lib.rs +++ b/crates/pecos-cppsparsestab/src/lib.rs @@ -172,6 +172,10 @@ impl CppSparseStab { } impl QuantumSimulator for CppSparseStab { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { self.state_mut().clear(); // Don't reset the RNG - just reset the quantum state @@ -512,8 +516,4 @@ impl StabilizerTableauSimulator for CppSparseStab { fn destab_tableau(&self) -> String { self.format_generators(false) } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } diff --git a/crates/pecos-cuquantum-sys/Cargo.toml b/crates/pecos-cuquantum-sys/Cargo.toml index 4c22c8171..a1b3dc4cd 100644 --- a/crates/pecos-cuquantum-sys/Cargo.toml +++ b/crates/pecos-cuquantum-sys/Cargo.toml @@ -26,8 +26,6 @@ env_logger.workspace = true [features] default = [] -# Generate bindings at build time (requires cuQuantum headers) -runtime-bindgen = [] [package.metadata.docs.rs] # Don't try to build docs on docs.rs (no CUDA/cuQuantum available) diff --git a/crates/pecos-cuquantum/src/stabilizer.rs b/crates/pecos-cuquantum/src/stabilizer.rs index 9fdc3ee29..2f2799f65 100644 --- a/crates/pecos-cuquantum/src/stabilizer.rs +++ b/crates/pecos-cuquantum/src/stabilizer.rs @@ -524,6 +524,10 @@ impl QuantumSimulator for CuStabilizer { self.measurement_count = 0; self } + + fn num_qubits(&self) -> usize { + self.num_qubits + } } impl CliffordGateable for CuStabilizer { @@ -625,10 +629,6 @@ impl StabilizerTableauSimulator for CuStabilizer { fn destab_tableau(&self) -> String { unimplemented!("CuStabilizer does not support local tableau access") } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } impl ForcedMeasurement for CuStabilizer { diff --git a/crates/pecos-cuquantum/src/statevec.rs b/crates/pecos-cuquantum/src/statevec.rs index 57d5e1b64..3bf547935 100644 --- a/crates/pecos-cuquantum/src/statevec.rs +++ b/crates/pecos-cuquantum/src/statevec.rs @@ -539,6 +539,10 @@ impl QuantumSimulator for CuStateVec { .expect("Failed to reset state vector"); self } + + fn num_qubits(&self) -> usize { + self.num_qubits + } } impl CliffordGateable for CuStateVec { diff --git a/crates/pecos-decoder-core/Cargo.toml b/crates/pecos-decoder-core/Cargo.toml index e165df193..0b1031d92 100644 --- a/crates/pecos-decoder-core/Cargo.toml +++ b/crates/pecos-decoder-core/Cargo.toml @@ -15,6 +15,8 @@ description = "Core traits and utilities for PECOS decoders" ndarray.workspace = true thiserror.workspace = true anyhow.workspace = true +pecos-random.workspace = true +rayon.workspace = true [lints] workspace = true diff --git a/crates/pecos-decoder-core/src/adaptive.rs b/crates/pecos-decoder-core/src/adaptive.rs new file mode 100644 index 000000000..f937797eb --- /dev/null +++ b/crates/pecos-decoder-core/src/adaptive.rs @@ -0,0 +1,177 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Adaptive decoder wrapper for time-varying noise. +//! +//! Wraps any `ObservableDecoder` with automatic rebuilding when the +//! noise model changes. The decoder factory is called with a new DEM +//! whenever `update_noise` is invoked. +//! +//! Use cases: +//! - Neutral atoms: noise drifts on hour timescales (calibration drift) +//! - Trapped ions: slow parameter drift between recalibrations +//! - Any platform where the DEM becomes stale + +use crate::ObservableDecoder; +use crate::errors::DecoderError; + +/// Adaptive decoder that rebuilds when noise changes. +/// +/// Holds a decoder factory and the current DEM. When `update_dem` is +/// called with a new DEM string, the decoder is rebuilt transparently. +pub struct AdaptiveDecoder { + decoder: Box, + factory: Box Result, DecoderError>>, + current_dem: String, + rebuild_count: usize, + /// Calibration monitoring: recent outcomes (true = logical error). + recent_outcomes: std::collections::VecDeque, + /// Size of the monitoring window. + monitoring_window: usize, + /// Error rate threshold above which recalibration is recommended. + recalibration_threshold: f64, +} + +impl AdaptiveDecoder { + /// Create from a DEM string and factory. + /// + /// # Errors + /// + /// Returns `DecoderError` if the factory fails. + pub fn new(dem: &str, mut factory: F) -> Result + where + F: FnMut(&str) -> Result, DecoderError> + 'static, + { + let decoder = factory(dem)?; + Ok(Self { + decoder, + factory: Box::new(factory), + current_dem: dem.to_string(), + rebuild_count: 0, + recent_outcomes: std::collections::VecDeque::new(), + monitoring_window: 1000, + recalibration_threshold: 0.1, + }) + } + + /// Update the DEM and rebuild the decoder. + /// + /// # Errors + /// + /// Returns `DecoderError` if the factory fails on the new DEM. + pub fn update_dem(&mut self, new_dem: &str) -> Result<(), DecoderError> { + self.decoder = (self.factory)(new_dem)?; + self.current_dem = new_dem.to_string(); + self.rebuild_count += 1; + Ok(()) + } + + /// Number of times the decoder has been rebuilt. + #[must_use] + pub fn rebuild_count(&self) -> usize { + self.rebuild_count + } + + /// The current DEM string. + #[must_use] + pub fn current_dem(&self) -> &str { + &self.current_dem + } + + /// Report a logical outcome for calibration monitoring. + /// + /// `was_logical_error`: true if this QEC cycle resulted in a logical error. + /// The adaptive decoder tracks recent error rate and signals when + /// recalibration may be needed (noise model drift). + pub fn report_outcome(&mut self, was_logical_error: bool) { + self.recent_outcomes.push_back(was_logical_error); + if self.recent_outcomes.len() > self.monitoring_window { + self.recent_outcomes.pop_front(); + } + } + + /// Check if recalibration is recommended. + /// + /// Returns true if the recent error rate exceeds `recalibration_threshold`. + /// This suggests the noise model has drifted and the DEM should be regenerated. + #[must_use] + pub fn should_recalibrate(&self) -> bool { + if self.recent_outcomes.len() < self.monitoring_window / 2 { + return false; // Not enough data + } + let errors = self.recent_outcomes.iter().filter(|&&e| e).count(); + let rate = errors as f64 / self.recent_outcomes.len() as f64; + rate > self.recalibration_threshold + } + + /// Recent logical error rate from monitoring window. + #[must_use] + pub fn recent_error_rate(&self) -> f64 { + if self.recent_outcomes.is_empty() { + return 0.0; + } + let errors = self.recent_outcomes.iter().filter(|&&e| e).count(); + errors as f64 / self.recent_outcomes.len() as f64 + } + + /// Set the monitoring window size and recalibration threshold. + pub fn set_monitoring(&mut self, window: usize, threshold: f64) { + self.monitoring_window = window; + self.recalibration_threshold = threshold; + } +} + +impl ObservableDecoder for AdaptiveDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + self.decoder.decode_to_observables(syndrome) + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_adaptive_decode() { + let dec = AdaptiveDecoder::new("error(0.1) D0\n", |_dem| { + struct Zero; + impl ObservableDecoder for Zero { + fn decode_to_observables(&mut self, _: &[u8]) -> Result { + Ok(0) + } + } + Ok(Box::new(Zero)) + }); + assert!(dec.is_ok()); + let mut dec = dec.unwrap(); + assert_eq!(dec.decode_to_observables(&[0]).unwrap(), 0); + assert_eq!(dec.rebuild_count(), 0); + } + + #[test] + fn test_adaptive_update() { + let mut dec = AdaptiveDecoder::new("error(0.1) D0\n", |_dem| { + struct Zero; + impl ObservableDecoder for Zero { + fn decode_to_observables(&mut self, _: &[u8]) -> Result { + Ok(0) + } + } + Ok(Box::new(Zero)) + }) + .unwrap(); + + dec.update_dem("error(0.2) D0\n").unwrap(); + assert_eq!(dec.rebuild_count(), 1); + assert_eq!(dec.current_dem(), "error(0.2) D0\n"); + } +} diff --git a/crates/pecos-decoder-core/src/bp_matching.rs b/crates/pecos-decoder-core/src/bp_matching.rs new file mode 100644 index 000000000..a8d983f91 --- /dev/null +++ b/crates/pecos-decoder-core/src/bp_matching.rs @@ -0,0 +1,127 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Belief-matching: BP soft info → reweighted matching decoder. +//! +//! Wraps any `MatchingDecoder` with BP-computed edge weights. +//! The BP posteriors are computed by an external `BpWeightProvider`, +//! then fed to the matching decoder via `decode_with_weights`. +//! +//! This achieves belief-matching (Higgott 2022) with any matching backend: +//! - Fusion Blossom (MWPM, ~0.94% threshold) +//! - UF (already in BP+UF, ~0.5% threshold) +//! - `PyMatching` (if it had dynamic weights) + +use crate::correlated_decoder::MatchingDecoder; +use crate::correlation_table::CorrelationTable; +use crate::errors::DecoderError; + +/// Trait for providing BP-adjusted weights per syndrome. +pub trait BpWeightProvider { + /// Compute BP-adjusted matching graph edge weights for a syndrome. + /// Returns one weight per matching graph edge. + fn compute_weights(&mut self, syndrome: &[u8]) -> Vec; + + /// Number of matching graph edges. + fn num_edges(&self) -> usize; + + /// Check if this syndrome is trivial (predecoder can handle it). + fn is_trivial(&self, syndrome: &[u8]) -> Option; +} + +/// Belief-matching decoder: BP weights → matching decoder. +/// +/// Optionally performs a second pass with correlation table adjustment +/// (correlated belief-matching) for exploiting X-Z cross-lattice correlations. +pub struct BpMatchingDecoder { + matching: M, + bp: B, + /// Optional correlation table for two-pass correlated decoding. + correlation: Option, + /// Reusable buffer for adjusted weights in the second pass. + adjusted_weights: Vec, +} + +impl BpMatchingDecoder { + /// Create a single-pass belief-matching decoder. + pub fn new(matching: M, bp: B) -> Self { + let n = bp.num_edges(); + Self { + matching, + bp, + correlation: None, + adjusted_weights: vec![0.0; n], + } + } + + /// Create a two-pass correlated belief-matching decoder. + /// + /// First pass: BP weights → MWPM → matched edges. + /// Second pass: correlation table adjusts weights → MWPM again. + pub fn with_correlations(matching: M, bp: B, correlation: CorrelationTable) -> Self { + let n = bp.num_edges(); + Self { + matching, + bp, + correlation: Some(correlation), + adjusted_weights: vec![0.0; n], + } + } +} + +impl crate::ObservableDecoder for BpMatchingDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + // Predecoder fast path: only for zero-defect syndromes. + // At d>=5, always use full MWPM (predecoder can be suboptimal). + // At d=3, BP + predecoder is actually better than MWPM for simple + // syndromes, but we can't easily detect d here. So we skip the + // predecoder and let MWPM handle everything for consistency. + let num_defects = syndrome.iter().filter(|&&v| v != 0).count(); + if num_defects == 0 { + return Ok(0); + } + + // Compute BP-adjusted weights. + let bp_weights = self.bp.compute_weights(syndrome); + + if let Some(corr) = &self.correlation + && corr.has_correlations() { + // Two-pass correlated belief-matching. + + // First pass: decode with BP weights to get matched edges. + let (_, matched_edges) = + self.matching.decode_with_weights(syndrome, &bp_weights)?; + + // Apply correlation adjustments to BP weights. + self.adjusted_weights.copy_from_slice(&bp_weights); + for &edge_idx in &matched_edges { + if edge_idx < corr.implied_weights.len() { + for iw in &corr.implied_weights[edge_idx] { + if iw.conditional_weight < self.adjusted_weights[iw.target_edge_idx] { + self.adjusted_weights[iw.target_edge_idx] = iw.conditional_weight; + } + } + } + } + + // Second pass: decode with correlation-adjusted weights. + let (obs, _) = self + .matching + .decode_with_weights(syndrome, &self.adjusted_weights)?; + return Ok(obs); + } + + // Single-pass belief-matching. + let (obs, _) = self.matching.decode_with_weights(syndrome, &bp_weights)?; + Ok(obs) + } +} diff --git a/crates/pecos-decoder-core/src/committed_osd.rs b/crates/pecos-decoder-core/src/committed_osd.rs new file mode 100644 index 000000000..8157cd6a8 --- /dev/null +++ b/crates/pecos-decoder-core/src/committed_osd.rs @@ -0,0 +1,175 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! OSD with software commitment for streaming decoding. +//! +//! Wraps an `ObservableSubgraphDecoder` with per-detector commitment +//! tracking. Committed detectors are masked during future decodes, +//! implementing the "software commitment" concept from Cain et al. +//! (arXiv:2505.13587). +//! +//! This enables streaming: decode a region, commit it, decode the next +//! region. Only uncommitted detectors participate in matching. + +use crate::ObservableDecoder; +use crate::decode_budget::{DecodeStrategy, DetectorRegion}; +use crate::errors::DecoderError; +use crate::observable_subgraph::ObservableSubgraphDecoder; + +/// Observable subgraph decoder with software commitment. +/// +/// After decoding a region, call `commit_range()` to mark those +/// detectors as finalized. Future decodes will mask committed +/// detectors (treat as syndrome=0), preventing re-matching of +/// already-corrected errors. +/// +/// The total correction is `committed_obs ^ active_obs`: the XOR +/// of committed corrections and the latest active decode. +pub struct CommittedOsdDecoder { + /// The underlying OSD (unchanged). + inner: ObservableSubgraphDecoder, + /// Per-detector commitment state. True = committed. + committed: Vec, + /// Accumulated observable correction from committed regions. + committed_obs: u64, + /// Total number of detectors. + num_detectors: usize, + /// Reusable masked syndrome buffer. + masked_syndrome: Vec, +} + +impl CommittedOsdDecoder { + /// Wrap an existing OSD with commitment tracking. + #[must_use] + pub fn new(inner: ObservableSubgraphDecoder, num_detectors: usize) -> Self { + Self { + inner, + committed: vec![false; num_detectors], + committed_obs: 0, + num_detectors, + masked_syndrome: vec![0u8; num_detectors], + } + } + + /// Decode only uncommitted detectors. + /// + /// Committed detectors are masked to 0 before passing to the + /// inner OSD. Returns the correction for the active (uncommitted) + /// region. + pub fn decode_active(&mut self, syndrome: &[u8]) -> Result { + // Build masked syndrome: zero out committed detectors + let len = syndrome.len().min(self.num_detectors); + self.masked_syndrome[..len].copy_from_slice(&syndrome[..len]); + for i in 0..len { + if self.committed[i] { + self.masked_syndrome[i] = 0; + } + } + self.inner + .decode_to_observables(&self.masked_syndrome[..len]) + } + + /// Mark detectors in [start, end) as committed. + /// + /// Before committing, decodes the full syndrome to get the + /// correction that includes the about-to-be-committed region. + /// The committed correction is stored for accumulation. + pub fn commit_range( + &mut self, + syndrome: &[u8], + region: &DetectorRegion, + ) -> Result { + // Decode with current syndrome (including uncommitted detectors) + let obs = self.decode_active(syndrome)?; + + // Mark detectors as committed + for i in region.start..region.end.min(self.num_detectors) { + self.committed[i] = true; + } + + // Accumulate the correction + self.committed_obs ^= obs; + Ok(obs) + } + + /// Total correction: committed + latest active. + /// + /// Call `decode_active` first to get the active correction, + /// then XOR with `committed_obs` for the full correction. + #[must_use] + pub fn committed_obs(&self) -> u64 { + self.committed_obs + } + + /// Number of committed detectors. + #[must_use] + pub fn num_committed(&self) -> usize { + self.committed.iter().filter(|&&c| c).count() + } + + /// Reset all commitment state for the next shot. + pub fn reset(&mut self) { + self.committed.fill(false); + self.committed_obs = 0; + } +} + +impl ObservableDecoder for CommittedOsdDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + // Full decode: committed XOR active + let active = self.decode_active(syndrome)?; + Ok(self.committed_obs ^ active) + } +} + +impl DecodeStrategy for CommittedOsdDecoder { + fn decode(&mut self, syndrome: &[u8]) -> Result { + self.decode_active(syndrome) + } + + fn commit(&mut self, region: &DetectorRegion) -> Result { + // Commit with zeros — the actual syndrome was already decoded + // via decode(). Just mark the region. + for i in region.start..region.end.min(self.num_detectors) { + self.committed[i] = true; + } + Ok(self.committed_obs) + } + + fn committed_obs(&self) -> u64 { + self.committed_obs + } + + fn reset(&mut self) { + CommittedOsdDecoder::reset(self); + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_detector_region() { + let r = DetectorRegion { start: 5, end: 15 }; + assert_eq!(r.len(), 10); + assert!(r.contains(5)); + assert!(!r.contains(15)); + } + + #[test] + fn test_decode_strategy_trait() { + // Verify the trait exists and has the right methods + // (compile-time check via trait bound) + fn _assert_strategy() {} + } +} diff --git a/crates/pecos-decoder-core/src/correlated_decoder.rs b/crates/pecos-decoder-core/src/correlated_decoder.rs new file mode 100644 index 000000000..4c3f81e4c --- /dev/null +++ b/crates/pecos-decoder-core/src/correlated_decoder.rs @@ -0,0 +1,243 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Two-pass correlated MWPM decoder (DGR-style). +//! +//! Wraps any `ObservableDecoder` that also supports a `decode_with_weights` +//! interface. After a training phase to build correlation statistics, each +//! shot is decoded twice: +//! +//! 1. First pass with alignment-corrected weights (from observed frequencies) +//! 2. Second pass with correlation-adjusted weights (from first-pass matching) +//! +//! This improves accuracy by exploiting pairwise edge correlations that +//! standard MWPM ignores. + +use crate::correlated_reweighting::EdgeCorrelationTracker; +use crate::errors::DecoderError; + +/// Configuration for the correlated decoder. +#[derive(Debug, Clone)] +pub struct CorrelatedDecoderConfig { + /// Number of training shots before enabling correlation re-weighting. + /// During training, shots are decoded normally and matchings are recorded. + pub training_shots: usize, + /// Whether to use alignment re-weighting (update base weights from + /// observed edge frequencies). + pub use_alignment: bool, + /// Whether to use correlation re-weighting (per-shot two-pass decode). + pub use_correlation: bool, +} + +impl Default for CorrelatedDecoderConfig { + fn default() -> Self { + Self { + training_shots: 1000, + use_alignment: true, + use_correlation: true, + } + } +} + +/// Trait for decoders that can report which edges were matched. +/// +/// This is needed for the correlation tracker to build statistics. +/// The decoder must return both the observable mask and the matched edge +/// indices from each decode. +pub trait MatchingDecoder { + /// Decode a syndrome and return (`observable_mask`, `matched_edge_indices`). + fn decode_with_matching(&mut self, syndrome: &[u8]) -> Result<(u64, Vec), DecoderError>; + + /// Decode with adjusted per-edge weights. + /// The weights slice has one entry per edge in the matching graph. + fn decode_with_weights( + &mut self, + syndrome: &[u8], + weights: &[f64], + ) -> Result<(u64, Vec), DecoderError>; + + /// Number of edges in the matching graph. + fn num_edges(&self) -> usize; +} + +/// Extension of `MatchingDecoder` that exposes per-edge metadata. +/// +/// Used by overlapping/sandwich windowed decoders to classify matched edges +/// as core or buffer based on endpoint locations and weight thresholds. +pub trait EdgeTrackingDecoder: MatchingDecoder { + /// First endpoint node index of the given edge. + fn edge_node1(&self, edge_idx: usize) -> u32; + + /// Second endpoint node index. Boundary nodes have index >= `num_detectors()`. + fn edge_node2(&self, edge_idx: usize) -> u32; + + /// Log-likelihood weight of the given edge. + fn edge_weight(&self, edge_idx: usize) -> f64; + + /// Observable bitmask for the given edge. + fn edge_obs_mask(&self, edge_idx: usize) -> u64; + + /// Number of detector nodes (not counting boundary/virtual nodes). + fn num_detectors(&self) -> usize; +} + +/// Two-pass correlated MWPM decoder. +/// +/// Wraps a `MatchingDecoder` with DGR-style correlation tracking and +/// re-weighting. Transparent to the `ObservableDecoder` interface -- +/// callers see the same API, just better accuracy. +pub struct CorrelatedDecoder { + inner: D, + tracker: EdgeCorrelationTracker, + config: CorrelatedDecoderConfig, + shots_decoded: usize, + /// Base weights (from DEM, updated by alignment after training). + base_weights: Vec, + /// Buffer for matched-edge flags (avoids per-shot allocation). + matched_flags: Vec, +} + +impl CorrelatedDecoder { + /// Create a new correlated decoder wrapping an inner decoder. + pub fn new(inner: D, base_weights: Vec, config: CorrelatedDecoderConfig) -> Self { + let num_edges = inner.num_edges(); + Self { + tracker: EdgeCorrelationTracker::new(num_edges), + matched_flags: vec![false; num_edges], + inner, + config, + shots_decoded: 0, + base_weights, + } + } + + /// Whether the training phase is complete. + #[must_use] + pub fn is_trained(&self) -> bool { + self.shots_decoded >= self.config.training_shots + } + + /// Number of training shots remaining. + #[must_use] + pub fn training_remaining(&self) -> usize { + self.config + .training_shots + .saturating_sub(self.shots_decoded) + } +} + +impl crate::ObservableDecoder for CorrelatedDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + self.shots_decoded += 1; + + // During training: decode normally, record matchings + if !self.is_trained() { + let (mask, matched_edges) = self.inner.decode_with_matching(syndrome)?; + self.tracker.record_matching(&matched_edges); + + // After training is complete, update base weights from alignment + if self.is_trained() && self.config.use_alignment { + self.base_weights = self.tracker.aligned_weights(); + } + + return Ok(mask); + } + + // After training: two-pass decode with correlation adjustment + + // First pass: decode with (possibly alignment-corrected) base weights + let (first_mask, first_matching) = self + .inner + .decode_with_weights(syndrome, &self.base_weights)?; + + // Record the matching for ongoing statistics + self.tracker.record_matching(&first_matching); + + if !self.config.use_correlation { + return Ok(first_mask); + } + + // Build matched-edge flags for correlation adjustment + self.matched_flags.fill(false); + for &e in &first_matching { + if e < self.matched_flags.len() { + self.matched_flags[e] = true; + } + } + + // Compute correlation-adjusted weights + let adjusted_weights = self + .tracker + .correlation_adjusted_weights(&self.base_weights, &self.matched_flags); + + // Second pass: re-decode with adjusted weights + let (second_mask, _) = self + .inner + .decode_with_weights(syndrome, &adjusted_weights)?; + + Ok(second_mask) + } +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::ObservableDecoder; + + /// Simple mock decoder for testing. + struct MockDecoder { + num_edges: usize, + } + + impl MatchingDecoder for MockDecoder { + fn decode_with_matching( + &mut self, + _syndrome: &[u8], + ) -> Result<(u64, Vec), DecoderError> { + Ok((0, vec![0, 2])) + } + + fn decode_with_weights( + &mut self, + _syndrome: &[u8], + _weights: &[f64], + ) -> Result<(u64, Vec), DecoderError> { + Ok((0, vec![0, 2])) + } + + fn num_edges(&self) -> usize { + self.num_edges + } + } + + #[test] + fn test_training_phase() { + let mock = MockDecoder { num_edges: 5 }; + let weights = vec![1.0; 5]; + let config = CorrelatedDecoderConfig { + training_shots: 3, + ..Default::default() + }; + let mut decoder = CorrelatedDecoder::new(mock, weights, config); + + assert!(!decoder.is_trained()); + assert_eq!(decoder.training_remaining(), 3); + + // Decode 3 training shots + for _ in 0..3 { + let _ = decoder.decode_to_observables(&[0, 0, 0]); + } + + assert!(decoder.is_trained()); + assert_eq!(decoder.training_remaining(), 0); + } +} diff --git a/crates/pecos-decoder-core/src/correlated_reweighting.rs b/crates/pecos-decoder-core/src/correlated_reweighting.rs new file mode 100644 index 000000000..9b88f737d --- /dev/null +++ b/crates/pecos-decoder-core/src/correlated_reweighting.rs @@ -0,0 +1,274 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Correlated edge re-weighting for MWPM decoders. +//! +//! Implements a simplified version of the DGR (Decoding Graph Re-weighting) +//! scheme from arXiv:2311.16214. The key idea: after an initial MWPM decode, +//! adjust edge weights based on pairwise correlations between edges, then +//! re-decode with the adjusted weights. +//! +//! Two phases: +//! 1. **Alignment**: track edge frequencies across shots, update weights to +//! match observed probabilities (corrects for DEM inaccuracies). +//! 2. **Correlation**: for each shot, adjust weights based on which correlated +//! edges were/weren't in the initial matching, then re-decode. + +/// Tracks edge occurrence statistics for alignment and correlation re-weighting. +pub struct EdgeCorrelationTracker { + /// Number of edges in the matching graph. + num_edges: usize, + /// Number of shots observed. + num_shots: usize, + /// Per-edge occurrence count (how many times edge appeared in a matching). + edge_counts: Vec, + /// Pairwise co-occurrence counts: `co_counts`[i * `num_edges` + j] = count of + /// edges i and j both appearing in the same matching. + /// Only stores upper triangle (i < j) to save memory. + co_counts: Vec, +} + +impl EdgeCorrelationTracker { + /// Create a new tracker for the given number of edges. + #[must_use] + pub fn new(num_edges: usize) -> Self { + // For large graphs, the co-occurrence matrix is O(E^2). + // At d=5 with ~200 edges, this is ~40K entries (320KB) -- fine. + // At d=9 with ~2000 edges, this is ~4M entries (32MB) -- manageable. + let co_size = num_edges * (num_edges - 1) / 2; + Self { + num_edges, + num_shots: 0, + edge_counts: vec![0; num_edges], + co_counts: vec![0; co_size], + } + } + + /// Index into the upper-triangle co-occurrence array. + fn co_index(&self, i: usize, j: usize) -> usize { + let (a, b) = if i < j { (i, j) } else { (j, i) }; + a * self.num_edges - a * (a + 1) / 2 + b - a - 1 + } + + /// Record a matching result: which edges were selected. + pub fn record_matching(&mut self, matched_edges: &[usize]) { + self.num_shots += 1; + + // Update single-edge counts + for &e in matched_edges { + if e < self.num_edges { + self.edge_counts[e] += 1; + } + } + + // Update co-occurrence counts for all pairs in the matching + for (idx_a, &e_a) in matched_edges.iter().enumerate() { + for &e_b in &matched_edges[idx_a + 1..] { + if e_a < self.num_edges && e_b < self.num_edges && e_a != e_b { + let co_idx = self.co_index(e_a, e_b); + if co_idx < self.co_counts.len() { + self.co_counts[co_idx] += 1; + } + } + } + } + } + + /// Get the empirical probability of edge e appearing in a matching. + #[must_use] + pub fn edge_probability(&self, e: usize) -> f64 { + if self.num_shots == 0 || e >= self.num_edges { + return 0.0; + } + self.edge_counts[e] as f64 / self.num_shots as f64 + } + + /// Get the empirical co-occurrence probability of edges i and j. + #[must_use] + pub fn co_occurrence_probability(&self, i: usize, j: usize) -> f64 { + if self.num_shots == 0 || i >= self.num_edges || j >= self.num_edges || i == j { + return 0.0; + } + let co_idx = self.co_index(i, j); + if co_idx >= self.co_counts.len() { + return 0.0; + } + self.co_counts[co_idx] as f64 / self.num_shots as f64 + } + + /// Number of shots recorded. + #[must_use] + pub fn num_shots(&self) -> usize { + self.num_shots + } + + /// Compute alignment-reweighted edge weights. + /// + /// Replaces original DEM weights with weights derived from observed + /// edge frequencies: `w_e` = -`ln(p_e` / (1 - `p_e`)) where `p_e` is the + /// empirical edge probability. + #[must_use] + pub fn aligned_weights(&self) -> Vec { + (0..self.num_edges) + .map(|e| { + let p = self.edge_probability(e); + if p <= 0.0 || p >= 1.0 { + // Edge never/always matched -- keep a default weight + if p <= 0.0 { 20.0 } else { 0.0 } + } else { + ((1.0 - p) / p).ln() + } + }) + .collect() + } + + /// Compute correlation-adjusted weights for a specific matching. + /// + /// Given an initial matching M, adjust each edge weight based on + /// correlations with matched/unmatched edges (DGR Equation 1): + /// + /// `w̃_j` = `w_j` - Σ_{`e_i` ∈ M} `p(e_i,e_j)/p(e_i)` + Σ_{`e_i` ∉ M} `p(e_i,e_j)/p(e_i)` + /// + /// Intuition: if edge j is correlated with matched edges, decrease its + /// weight (make it more likely). If correlated with unmatched edges, + /// increase its weight (make it less likely). + /// Compute correlation-adjusted weights for a specific matching. + /// + /// Given an initial matching M, adjust each edge weight based on + /// correlations with matched/unmatched edges (DGR Equation 1): + /// + /// `w̃_j` = `w_j` - Σ_{`e_i` ∈ M} `p(e_i,e_j)/p(e_i)` + Σ_{`e_i` ∉ M} `p(e_i,e_j)/p(e_i)` + /// + /// Only edges with significant correlation (conditional probability > + /// `min_conditional`) contribute to the sum. This avoids the bias from + /// summing over hundreds of near-zero terms. + #[must_use] + pub fn correlation_adjusted_weights( + &self, + base_weights: &[f64], + matched_edges: &[bool], + ) -> Vec { + self.correlation_adjusted_weights_filtered(base_weights, matched_edges, 0.05) + } + + /// Correlation adjustment with configurable significance threshold. + /// + /// `min_conditional`: minimum p(i,j)/p(i) to include an edge pair. + /// Higher values mean fewer pairs contribute (sparser adjustment). + #[must_use] + pub fn correlation_adjusted_weights_filtered( + &self, + base_weights: &[f64], + matched_edges: &[bool], + min_conditional: f64, + ) -> Vec { + let mut adjusted = base_weights.to_vec(); + + for j in 0..self.num_edges { + let mut adjustment = 0.0; + for i in 0..self.num_edges { + if i == j { + continue; + } + let p_i = self.edge_probability(i); + if p_i <= 0.0 { + continue; + } + let p_ij = self.co_occurrence_probability(i, j); + let conditional = p_ij / p_i; + + // Only include significantly correlated pairs + if conditional < min_conditional { + continue; + } + + if matched_edges[i] { + // Correlated edge is matched -> decrease weight (more likely). + // We only adjust for matched edges -- the unmatched term + // creates a large positive bias that dominates when most + // edges are unmatched. + adjustment -= conditional; + } + } + adjusted[j] += adjustment; + // Clamp to prevent negative weights + if adjusted[j] < 0.0 { + adjusted[j] = 0.0; + } + } + + adjusted + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_tracker_basic() { + let mut tracker = EdgeCorrelationTracker::new(5); + + // Record some matchings + tracker.record_matching(&[0, 2]); + tracker.record_matching(&[0, 3]); + tracker.record_matching(&[1, 2]); + tracker.record_matching(&[0, 2]); + + assert_eq!(tracker.num_shots(), 4); + assert!((tracker.edge_probability(0) - 0.75).abs() < 1e-10); + assert!((tracker.edge_probability(1) - 0.25).abs() < 1e-10); + assert!((tracker.edge_probability(2) - 0.75).abs() < 1e-10); + assert!((tracker.edge_probability(4) - 0.0).abs() < 1e-10); + + // Co-occurrence: edges 0 and 2 both appear in 2 matchings + assert!((tracker.co_occurrence_probability(0, 2) - 0.5).abs() < 1e-10); + // Edges 0 and 3 both appear in 1 matching + assert!((tracker.co_occurrence_probability(0, 3) - 0.25).abs() < 1e-10); + } + + #[test] + fn test_aligned_weights() { + let mut tracker = EdgeCorrelationTracker::new(3); + for _ in 0..100 { + tracker.record_matching(&[0]); + } + for _ in 0..900 { + tracker.record_matching(&[]); + } + // Edge 0 appears in 10% of matchings -> p=0.1 -> w = ln(0.9/0.1) = ln(9) ≈ 2.197 + let weights = tracker.aligned_weights(); + assert!((weights[0] - 9.0_f64.ln()).abs() < 0.01); + } + + #[test] + fn test_correlation_adjustment() { + let mut tracker = EdgeCorrelationTracker::new(3); + // Edges 0 and 1 are highly correlated (always appear together) + for _ in 0..100 { + tracker.record_matching(&[0, 1]); + } + for _ in 0..900 { + tracker.record_matching(&[]); + } + + let base_weights = vec![2.0, 2.0, 2.0]; + // If edge 0 is matched, edge 1's weight should decrease (correlated) + let matched = vec![true, false, false]; + let adjusted = tracker.correlation_adjusted_weights(&base_weights, &matched); + + // Edge 1 should have lower weight (more likely given edge 0 is matched) + assert!(adjusted[1] < base_weights[1]); + // Edge 2 should be unchanged (no correlation with edge 0) + assert!((adjusted[2] - base_weights[2]).abs() < 1e-10); + } +} diff --git a/crates/pecos-decoder-core/src/correlation_table.rs b/crates/pecos-decoder-core/src/correlation_table.rs new file mode 100644 index 000000000..2016da361 --- /dev/null +++ b/crates/pecos-decoder-core/src/correlation_table.rs @@ -0,0 +1,274 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Pre-computed correlation table from DEM decomposition. +//! +//! Extracts pairwise edge correlations from the `^` decomposition in a DEM +//! and pre-computes conditional weights for two-pass correlated decoding. +//! +//! The algorithm (matching `PyMatching`'s implementation): +//! +//! 1. Parse decomposed error mechanisms (with `^` separators) +//! 2. For each pair of components (A, B) in a decomposed mechanism with +//! probability p, accumulate joint probability: `p_joint = p_a*(1-p) + p*(1-p_a)` +//! 3. Also accumulate marginal probability for each edge +//! 4. Conditional probability: `P(B|A) = P_joint(A,B) / P_marginal(A)` +//! 5. Conditional weight: `w_cond = ln((1-P(B|A)) / P(B|A))` +//! +//! The conditional weight is only applied during decoding if it's LOWER than +//! the current weight (makes the correlated edge more likely). + +use crate::errors::DecoderError; +use std::collections::BTreeMap; + +/// An implied weight change: if edge (node1, node2) was matched, +/// change the weight of edge (`target_node1`, `target_node2`) to `conditional_weight`. +#[derive(Debug, Clone)] +pub struct ImpliedWeight { + /// Target edge (by index in the matching graph). + pub target_edge_idx: usize, + /// Conditional weight: the weight edge should have given the source was matched. + pub conditional_weight: f64, +} + +/// Pre-computed correlation table from DEM decomposition. +/// +/// For each edge in the matching graph, stores a list of implied weight +/// changes that should be applied when that edge is matched in the first +/// pass of a two-pass decode. +#[derive(Debug, Clone)] +pub struct CorrelationTable { + /// For each edge index, the list of implied weights for correlated edges. + pub implied_weights: Vec>, + /// Number of edges. + pub num_edges: usize, +} + +/// Edge key for lookup: (`min_node`, `max_node`), where `max_node` = `u32::MAX` for boundary. +type EdgeKey = (u32, u32); + +/// Independent probability combination (Bernoulli XOR): +/// `p_combined = p_a * (1 - p_b) + p_b * (1 - p_a)` +fn bernoulli_xor(p_a: f64, p_b: f64) -> f64 { + p_a * (1.0 - p_b) + p_b * (1.0 - p_a) +} + +/// Convert probability to weight for correlations: `ln((1-p) / p)` +/// Clamped to avoid infinite weights. +fn prob_to_weight(p: f64) -> f64 { + let p_clamped = p.clamp(1e-15, 0.5); + ((1.0 - p_clamped) / p_clamped).ln() +} + +impl CorrelationTable { + /// Build a correlation table from a DEM string. + /// + /// Parses the DEM, identifies decomposed error mechanisms (with `^`), + /// computes joint probabilities between component pairs, and derives + /// conditional weights. + /// + /// `edge_index_map` maps (node1, node2) pairs to edge indices in the + /// matching graph (after merging). This must match the decoder's edge + /// indexing. + /// + /// # Errors + /// + /// Returns `DecoderError` if the DEM is malformed. + pub fn from_dem_str( + dem: &str, + edge_index_map: &BTreeMap, + num_edges: usize, + ) -> Result { + // Accumulate joint and marginal probabilities. + // joint_probs[(edge_A, edge_B)] = P(A and B both fire from shared mechanisms) + // marginal_probs[edge_A] = P(A fires from any mechanism) + let mut joint_probs: BTreeMap<(EdgeKey, EdgeKey), f64> = BTreeMap::new(); + + for line in dem.lines() { + let line = line.trim(); + if !line.starts_with("error(") { + continue; + } + + let close_paren = line.find(')').ok_or_else(|| { + DecoderError::InvalidConfiguration("Missing closing parenthesis".into()) + })?; + let prob_str = &line[6..close_paren]; + let probability: f64 = prob_str.parse().map_err(|_| { + DecoderError::InvalidConfiguration(format!("Invalid probability: {prob_str}")) + })?; + + if probability <= 0.0 || probability > 0.5 { + continue; + } + + let tokens_str = &line[close_paren + 1..]; + let components: Vec<&str> = tokens_str.split('^').collect(); + + if components.len() < 2 { + // Non-decomposed mechanism: accumulate marginal only + let key = parse_component_edge_key(components[0]); + if let Some(key) = key { + let marginal = joint_probs.entry((key, key)).or_insert(0.0); + *marginal = bernoulli_xor(*marginal, probability); + } + continue; + } + + // Decomposed mechanism: accumulate joint and marginal for all pairs + let mut component_keys: Vec = Vec::new(); + for component in &components { + if let Some(key) = parse_component_edge_key(component) { + component_keys.push(key); + } + } + + // Joint probabilities for all pairs + for i in 0..component_keys.len() { + for j in (i + 1)..component_keys.len() { + let k0 = component_keys[i]; + let k1 = component_keys[j]; + let p01 = joint_probs.entry((k0, k1)).or_insert(0.0); + *p01 = bernoulli_xor(*p01, probability); + let p10 = joint_probs.entry((k1, k0)).or_insert(0.0); + *p10 = bernoulli_xor(*p10, probability); + } + } + + // Marginal for each component + for &key in &component_keys { + let marginal = joint_probs.entry((key, key)).or_insert(0.0); + *marginal = bernoulli_xor(*marginal, probability); + } + } + + // Build implied weight table + let mut implied_weights: Vec> = vec![Vec::new(); num_edges]; + + for (&(causal_key, affected_key), &joint_p) in &joint_probs { + if causal_key == affected_key { + continue; // Skip marginals + } + + let marginal_p = joint_probs + .get(&(causal_key, causal_key)) + .copied() + .unwrap_or(0.0); + if marginal_p <= 0.0 { + continue; + } + + let conditional_p = (joint_p / marginal_p).min(0.5); + if conditional_p <= 0.0 { + continue; + } + + let conditional_weight = prob_to_weight(conditional_p); + + if let (Some(&causal_idx), Some(&affected_idx)) = ( + edge_index_map.get(&causal_key), + edge_index_map.get(&affected_key), + ) { + implied_weights[causal_idx].push(ImpliedWeight { + target_edge_idx: affected_idx, + conditional_weight, + }); + } + } + + Ok(Self { + implied_weights, + num_edges, + }) + } + + /// Check if the table has any correlations. + #[must_use] + pub fn has_correlations(&self) -> bool { + self.implied_weights.iter().any(|v| !v.is_empty()) + } + + /// Number of correlated edge pairs. + #[must_use] + pub fn num_correlations(&self) -> usize { + self.implied_weights.iter().map(Vec::len).sum() + } +} + +/// Parse detector indices from a DEM component string, return edge key. +fn parse_component_edge_key(component: &str) -> Option { + let mut detectors: Vec = Vec::new(); + for token in component.split_whitespace() { + if let Some(d_str) = token.strip_prefix('D') + && let Ok(d) = d_str.parse::() { + detectors.push(d); + } + } + match detectors.len() { + 0 => None, // Pure observable, no edge + 1 => Some((detectors[0], u32::MAX)), // Boundary edge + 2 => { + let (a, b) = if detectors[0] <= detectors[1] { + (detectors[0], detectors[1]) + } else { + (detectors[1], detectors[0]) + }; + Some((a, b)) + } + _ => None, // Hyperedge, skip + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_bernoulli_xor() { + assert!((bernoulli_xor(0.1, 0.2) - 0.26).abs() < 1e-10); + assert!((bernoulli_xor(0.0, 0.5) - 0.5).abs() < 1e-10); + assert!((bernoulli_xor(0.5, 0.5) - 0.5).abs() < 1e-10); + } + + #[test] + fn test_decomposed_dem() { + // DEM with one decomposed mechanism: D0 D1 ^ D2 D3 + // When D0-D1 is matched, D2-D3 should get a lower weight + let dem = "error(0.01) D0 D1 ^ D2 D3\nerror(0.02) D0 D1\nerror(0.02) D2 D3"; + + let mut edge_map = BTreeMap::new(); + edge_map.insert((0, 1), 0usize); // D0-D1 = edge 0 + edge_map.insert((2, 3), 1usize); // D2-D3 = edge 1 + + let table = CorrelationTable::from_dem_str(dem, &edge_map, 2).unwrap(); + assert!(table.has_correlations()); + + // Edge 0 should have an implied weight for edge 1 + assert!(!table.implied_weights[0].is_empty()); + let iw = &table.implied_weights[0][0]; + assert_eq!(iw.target_edge_idx, 1); + // The conditional weight should be lower than the unconditional + let unconditional_weight = prob_to_weight(0.02 + 0.01); // approximate + assert!(iw.conditional_weight < unconditional_weight); + } + + #[test] + fn test_no_decomposition() { + let dem = "error(0.01) D0 D1\nerror(0.02) D2 D3"; + let mut edge_map = BTreeMap::new(); + edge_map.insert((0, 1), 0usize); + edge_map.insert((2, 3), 1usize); + + let table = CorrelationTable::from_dem_str(dem, &edge_map, 2).unwrap(); + assert!(!table.has_correlations()); + } +} diff --git a/crates/pecos-decoder-core/src/decode_budget.rs b/crates/pecos-decoder-core/src/decode_budget.rs new file mode 100644 index 000000000..b3bca9aa1 --- /dev/null +++ b/crates/pecos-decoder-core/src/decode_budget.rs @@ -0,0 +1,236 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Decode budget and strategy framework for real-time QEC. +//! +//! Different hardware platforms have different time budgets for decoding: +//! superconducting (~1μs), neutral atoms (~1ms), ion traps (~10ms). +//! The framework selects the best decode strategy based on the budget. +//! +//! # Example +//! +//! ```ignore +//! let budget = DecodeBudget::neutral_atom(distance); +//! let strategy = CommittedOsdStrategy::new(osd, budget); +//! let decoder = LogicalCircuitDecoder::new(descriptor, strategy); +//! ``` + +use crate::errors::DecoderError; +use std::time::Duration; + +/// Time and resource budget for decoding. +/// +/// Two timing constraints govern QEC decoding: +/// +/// - **Throughput**: decoder must keep up with syndrome generation to +/// avoid backlog. Measured in time per syndrome round. +/// - **Reaction time**: at feed-forward decision points (T gates, magic +/// state injection), the decoder must produce a correction within a +/// deadline. For Clifford-only circuits, this is unlimited (corrections +/// are metadata applied at the end). +/// +/// The budget also controls the accuracy/latency trade-off via window +/// size and overlap parameters. +#[derive(Debug, Clone)] +pub struct DecodeBudget { + /// Maximum wall-clock time per decode at a decision point. + /// For Clifford circuits this is unlimited; for T gates it's + /// the time between last syndrome and correction application. + pub reaction_time: Duration, + /// Maximum detectors to include in a single decode call. + /// Controls memory usage and decode time. + pub max_window_detectors: usize, + /// Number of overlap rounds at window boundaries. + /// More overlap = better accuracy, more compute. + /// Set to 0 for non-overlapping (fastest, least accurate). + pub overlap_rounds: usize, + /// Code distance (used to scale window sizes). + pub code_distance: usize, +} + +impl DecodeBudget { + /// Unlimited budget: full-circuit decode. Maximum accuracy. + /// + /// Use for Clifford-only circuits (no feed-forward decisions), + /// offline simulation, or any situation where the decoder can + /// take as long as needed. + #[must_use] + pub fn unlimited() -> Self { + Self { + reaction_time: Duration::from_hours(1), + max_window_detectors: usize::MAX, + overlap_rounds: usize::MAX, + code_distance: 0, + } + } + + /// Create a budget from the reaction time at decision points. + /// + /// `reaction_time`: time available between last syndrome and when + /// the correction must be applied (e.g., at T gate injection). + /// + /// Window size and overlap are scaled based on available time: + /// - Very generous (>100ms): unlimited (full-circuit decode) + /// - Generous (1ms - 100ms): large windows, d overlap + /// - Medium (10μs - 1ms): d-round windows, d/2 overlap + /// - Tight (<10μs): minimal windows, no overlap + #[must_use] + pub fn from_reaction_time(reaction_time: Duration, distance: usize) -> Self { + let us = reaction_time.as_micros() as usize; + + let (max_dets, overlap) = if us >= 100_000 { + (usize::MAX, usize::MAX) + } else if us >= 1_000 { + (distance * distance * 4 * distance, distance) + } else if us >= 10 { + (distance * distance * 2 * distance, distance / 2) + } else { + (distance * distance * 2, 0) + }; + + Self { + reaction_time, + max_window_detectors: max_dets, + overlap_rounds: overlap, + code_distance: distance, + } + } + + /// Create a budget with explicit parameters. + #[must_use] + pub fn with_params( + reaction_time: Duration, + max_window_detectors: usize, + overlap_rounds: usize, + code_distance: usize, + ) -> Self { + Self { + reaction_time, + max_window_detectors, + overlap_rounds, + code_distance, + } + } + + /// Whether the budget allows full-circuit decoding (unlimited window). + #[must_use] + pub fn is_unlimited(&self) -> bool { + self.max_window_detectors == usize::MAX && self.overlap_rounds == usize::MAX + } + + /// Whether windowed decoding is needed (non-unlimited budget). + #[must_use] + pub fn is_windowed(&self) -> bool { + !self.is_unlimited() + } +} + +/// A region of detectors in the circuit. +/// +/// Represents a contiguous block of detectors by their global indices. +/// Used by strategies to define decode/commit boundaries. +#[derive(Debug, Clone)] +pub struct DetectorRegion { + /// First global detector index in this region. + pub start: usize, + /// One past the last global detector index. + pub end: usize, +} + +impl DetectorRegion { + /// Number of detectors in this region. + #[must_use] + pub fn len(&self) -> usize { + self.end.saturating_sub(self.start) + } + + /// Whether the region is empty. + #[must_use] + pub fn is_empty(&self) -> bool { + self.start >= self.end + } + + /// Whether a detector index is in this region. + #[must_use] + pub fn contains(&self, det: usize) -> bool { + det >= self.start && det < self.end + } +} + +/// Strategy for decoding a logical circuit. +/// +/// Strategies implement different decode/commit patterns depending +/// on the time budget. All strategies produce the same type of output +/// (observable correction mask) but with different accuracy/latency +/// trade-offs. +pub trait DecodeStrategy: Send + Sync { + /// Decode a syndrome and return the observable correction mask. + /// + /// The syndrome covers the full circuit. The strategy decides + /// which portion to decode based on its internal state and budget. + fn decode(&mut self, syndrome: &[u8]) -> Result; + + /// Commit corrections for a detector region. + /// + /// After commitment, detectors in this region are excluded from + /// future decode calls. Their corrections are accumulated into + /// the committed observable mask. + fn commit(&mut self, region: &DetectorRegion) -> Result; + + /// Total committed observable correction so far. + fn committed_obs(&self) -> u64; + + /// Reset all state for the next shot. + fn reset(&mut self); +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_budget_unlimited() { + let b = DecodeBudget::unlimited(); + assert!(b.is_unlimited()); + assert!(!b.is_windowed()); + } + + #[test] + fn test_budget_from_reaction_time() { + // Very tight: no overlap + let b = DecodeBudget::from_reaction_time(Duration::from_micros(1), 7); + assert_eq!(b.overlap_rounds, 0); + assert!(b.is_windowed()); + + // Medium: d/2 overlap + let b = DecodeBudget::from_reaction_time(Duration::from_micros(100), 7); + assert_eq!(b.overlap_rounds, 3); + + // Generous: d overlap + let b = DecodeBudget::from_reaction_time(Duration::from_millis(10), 7); + assert_eq!(b.overlap_rounds, 7); + + // Very generous: unlimited + let b = DecodeBudget::from_reaction_time(Duration::from_millis(200), 7); + assert!(b.is_unlimited()); + } + + #[test] + fn test_detector_region() { + let r = DetectorRegion { start: 10, end: 20 }; + assert_eq!(r.len(), 10); + assert!(r.contains(10)); + assert!(r.contains(19)); + assert!(!r.contains(20)); + assert!(!r.contains(9)); + } +} diff --git a/crates/pecos-decoder-core/src/dem.rs b/crates/pecos-decoder-core/src/dem.rs index a04d96216..e497d7dea 100644 --- a/crates/pecos-decoder-core/src/dem.rs +++ b/crates/pecos-decoder-core/src/dem.rs @@ -200,6 +200,521 @@ pub mod utils { } } +/// Check matrix representation extracted from a Detector Error Model. +/// +/// Converts a DEM string into the matrices needed by check-matrix-based +/// decoders (BP+OSD, `UnionFind`, `RelayBP`, etc.): +/// +/// - **`check_matrix`** `H[d][m]`: 1 if error mechanism `m` flips detector `d` +/// - **`observable_matrix`** `L[o][m]`: 1 if mechanism `m` flips observable `o` +/// - **`error_priors`** `p[m]`: probability of mechanism `m` +/// +/// # Example +/// +/// ``` +/// use pecos_decoder_core::dem::DemCheckMatrix; +/// +/// let dem = "error(0.01) D0 D1 L0\nerror(0.02) D1 D2"; +/// let dcm = DemCheckMatrix::from_dem_str(dem).unwrap(); +/// assert_eq!(dcm.num_detectors, 3); +/// assert_eq!(dcm.num_observables, 1); +/// assert_eq!(dcm.num_mechanisms, 2); +/// assert_eq!(dcm.error_priors, vec![0.01, 0.02]); +/// ``` +#[derive(Debug, Clone)] +pub struct DemCheckMatrix { + /// Check matrix: rows = detectors, columns = error mechanisms. + pub check_matrix: ndarray::Array2, + /// Observable matrix: rows = observables, columns = error mechanisms. + pub observable_matrix: ndarray::Array2, + /// Error probability per mechanism. + pub error_priors: Vec, + /// Number of detectors (rows of `check_matrix`). + pub num_detectors: usize, + /// Number of observables (rows of `observable_matrix`). + pub num_observables: usize, + /// Number of error mechanisms (columns of both matrices). + pub num_mechanisms: usize, +} + +impl DemCheckMatrix { + /// Parse a DEM string into check matrix form. + /// + /// Each `error(p) D_i D_j ... L_k ...` line becomes one column in the + /// check matrix (for the D entries) and one column in the observable + /// matrix (for the L entries). Decomposed mechanisms (`D0 ^ D1`) are + /// combined by XOR. + /// + /// # Errors + /// + /// Returns [`DecoderError`] if the DEM string is malformed. + pub fn from_dem_str(dem: &str) -> Result { + // First pass: collect mechanisms and find dimensions. + let mut mechanisms: Vec<(f64, Vec, Vec)> = Vec::new(); + let mut max_detector: Option = None; + let mut max_observable: Option = None; + + for line in dem.lines() { + let line = line.trim(); + if line.is_empty() || line.starts_with('#') { + continue; + } + if !line.starts_with("error(") { + // Skip non-error lines (detector, logical_observable, etc.) + continue; + } + + // Parse "error(p) D0 D1 ... L0 ..." or "error(p) D0 ^ D1 ..." + let close_paren = line.find(')').ok_or_else(|| { + DecoderError::InvalidConfiguration( + "Missing closing parenthesis in error line".into(), + ) + })?; + let prob_str = &line[6..close_paren]; + let probability: f64 = prob_str.parse().map_err(|_| { + DecoderError::InvalidConfiguration(format!("Invalid probability: {prob_str}")) + })?; + + let tokens_str = &line[close_paren + 1..]; + + // Handle decomposed mechanisms (with ^) by XOR-ing components. + let mut det_set = std::collections::BTreeSet::new(); + let mut obs_set = std::collections::BTreeSet::new(); + + for component in tokens_str.split('^') { + for token in component.split_whitespace() { + if let Some(d_str) = token.strip_prefix('D') { + let d: u32 = d_str.parse().map_err(|_| { + DecoderError::InvalidConfiguration(format!("Invalid detector: {token}")) + })?; + // XOR: toggle membership + if !det_set.remove(&d) { + det_set.insert(d); + } + max_detector = Some(max_detector.map_or(d, |m| m.max(d))); + } else if let Some(l_str) = token.strip_prefix('L') { + let l: u32 = l_str.parse().map_err(|_| { + DecoderError::InvalidConfiguration(format!( + "Invalid observable: {token}" + )) + })?; + if !obs_set.remove(&l) { + obs_set.insert(l); + } + max_observable = Some(max_observable.map_or(l, |m| m.max(l))); + } + } + } + + let detectors: Vec = det_set.into_iter().collect(); + let observables: Vec = obs_set.into_iter().collect(); + mechanisms.push((probability, detectors, observables)); + } + + let num_detectors = max_detector.map_or(0, |m| m as usize + 1); + let num_observables = max_observable.map_or(0, |m| m as usize + 1); + let num_mechanisms = mechanisms.len(); + + // Build matrices. + let mut check_matrix = ndarray::Array2::::zeros((num_detectors, num_mechanisms)); + let mut observable_matrix = ndarray::Array2::::zeros((num_observables, num_mechanisms)); + let mut error_priors = Vec::with_capacity(num_mechanisms); + + for (col, (prob, detectors, observables)) in mechanisms.iter().enumerate() { + error_priors.push(*prob); + for &d in detectors { + check_matrix[[d as usize, col]] = 1; + } + for &o in observables { + observable_matrix[[o as usize, col]] = 1; + } + } + + Ok(Self { + check_matrix, + observable_matrix, + error_priors, + num_detectors, + num_observables, + num_mechanisms, + }) + } + + /// Compute the observable prediction from a correction vector. + /// + /// Given a binary correction vector (one entry per mechanism, from a + /// check-matrix decoder), returns the observable mask as + /// `observable_matrix @ correction (mod 2)`. + #[must_use] + pub fn observables_from_correction(&self, correction: &[u8]) -> Vec { + let mut obs = vec![0u8; self.num_observables]; + for (o, row) in self.observable_matrix.rows().into_iter().enumerate() { + let mut sum = 0u8; + for (m, &val) in row.iter().enumerate() { + if val != 0 && m < correction.len() && correction[m] != 0 { + sum ^= 1; + } + } + obs[o] = sum; + } + obs + } + + /// Pack observable predictions into a bitmask (u64). + /// + /// Bit `i` is set if observable `i` is predicted to flip. + #[must_use] + pub fn observables_mask_from_correction(&self, correction: &[u8]) -> u64 { + let obs = self.observables_from_correction(correction); + let mut mask = 0u64; + for (i, &v) in obs.iter().enumerate() { + if v != 0 { + mask |= 1 << i; + } + } + mask + } +} + +/// An edge in a matching graph extracted from a DEM. +#[derive(Debug, Clone)] +pub struct MatchingEdge { + /// First detector node (always present). + pub node1: u32, + /// Second detector node, or `None` for a boundary edge. + pub node2: Option, + /// Weight for MWPM: `ln((1-p) / p)`. + pub weight: f64, + /// Observable indices flipped by this error. + pub observables: Vec, + /// Original error probability. + pub probability: f64, + /// Fault mechanism ID (DEM line number). Components from the same + /// decomposed mechanism share the same `fault_id`. + pub fault_id: usize, +} + +/// Matching graph representation extracted from a Detector Error Model. +/// +/// Parses a DEM into edges suitable for MWPM decoders (`PyMatching`, Fusion +/// Blossom). Each graphlike error mechanism (1-2 detectors) becomes one edge. +/// Decomposed mechanisms (`D0 ^ D1`) are split into their components. +/// Hyperedges (3+ detectors after resolution) are skipped with a warning. +/// +/// # Example +/// +/// ``` +/// use pecos_decoder_core::dem::DemMatchingGraph; +/// +/// let dem = "error(0.01) D0 D1 L0\nerror(0.02) D1"; +/// let graph = DemMatchingGraph::from_dem_str(dem).unwrap(); +/// assert_eq!(graph.edges.len(), 2); +/// assert_eq!(graph.num_detectors, 2); +/// ``` +#[derive(Debug, Clone)] +pub struct DemMatchingGraph { + /// Edges in the matching graph. + pub edges: Vec, + /// Number of detectors (max detector ID + 1). + pub num_detectors: usize, + /// Number of observables (max observable ID + 1). + pub num_observables: usize, + /// Number of hyperedges skipped (3+ detectors). + pub skipped_hyperedges: usize, + /// Detector coordinates (from `detector(x,y,t) D_i` declarations). + /// Indexed by detector ID. Empty if no detector declarations in DEM. + pub detector_coords: Vec>>, +} + +impl DemMatchingGraph { + /// Parse a DEM string into a matching graph. + /// + /// # Errors + /// + /// Returns [`DecoderError`] if the DEM string is malformed. + pub fn from_dem_str(dem: &str) -> Result { + let mut edges = Vec::new(); + let mut max_detector: Option = None; + let mut max_observable: Option = None; + let mut skipped = 0usize; + let mut fault_id = 0usize; + + for line in dem.lines() { + let line = line.trim(); + if line.is_empty() || line.starts_with('#') || !line.starts_with("error(") { + continue; + } + + let close_paren = line.find(')').ok_or_else(|| { + DecoderError::InvalidConfiguration("Missing closing parenthesis".into()) + })?; + let prob_str = &line[6..close_paren]; + let probability: f64 = prob_str.parse().map_err(|_| { + DecoderError::InvalidConfiguration(format!("Invalid probability: {prob_str}")) + })?; + + if probability <= 0.0 { + continue; + } + + let weight = if probability < 1.0 { + ((1.0 - probability) / probability).ln() + } else { + 0.0 + }; + + let tokens_str = &line[close_paren + 1..]; + + // For decomposed mechanisms (with ^), each component is a separate edge. + // For non-decomposed mechanisms, there's one component. + let components: Vec<&str> = tokens_str.split('^').collect(); + + for component in &components { + let mut detectors = Vec::new(); + let mut observables = Vec::new(); + + for token in component.split_whitespace() { + if let Some(d_str) = token.strip_prefix('D') { + let d: u32 = d_str.parse().map_err(|_| { + DecoderError::InvalidConfiguration(format!("Invalid detector: {token}")) + })?; + detectors.push(d); + max_detector = Some(max_detector.map_or(d, |m| m.max(d))); + } else if let Some(l_str) = token.strip_prefix('L') { + let l: u32 = l_str.parse().map_err(|_| { + DecoderError::InvalidConfiguration(format!( + "Invalid observable: {token}" + )) + })?; + observables.push(l); + max_observable = Some(max_observable.map_or(l, |m| m.max(l))); + } + } + + match detectors.len() { + 0 => {} // Pure observable error, skip + 1 => { + edges.push(MatchingEdge { + node1: detectors[0], + node2: None, // boundary + weight, + observables, + probability, + fault_id, + }); + } + 2 => { + edges.push(MatchingEdge { + node1: detectors[0], + node2: Some(detectors[1]), + weight, + observables, + probability, + fault_id, + }); + } + _ => { + skipped += 1; + } + } + } + fault_id += 1; + } + + let num_detectors = max_detector.map_or(0, |m| m as usize + 1); + let num_observables = max_observable.map_or(0, |m| m as usize + 1); + + let edges = Self::merge_parallel_edges(edges); + + // Parse detector coordinates + let coords = parse_detector_coords(dem); + let mut detector_coords = vec![None; num_detectors]; + for dc in coords { + if (dc.id as usize) < num_detectors { + detector_coords[dc.id as usize] = Some(dc.coords); + } + } + + Ok(Self { + edges, + num_detectors, + num_observables, + skipped_hyperedges: skipped, + detector_coords, + }) + } + + /// Merge edges with independent fault-ID-aware probability combination. + /// + /// Components from the same fault mechanism (same `fault_id`) that land on + /// the same edge pair are NOT merged -- they're part of one correlated event. + /// Components from different fault mechanisms (different `fault_id`) are + /// combined using: `p_combined = p_a*(1-p_b) + p_b*(1-p_a)`. + /// + /// This matches `PyMatching`'s "independent" merge strategy with fault ID tracking. + pub(crate) fn merge_parallel_edges(edges: Vec) -> Vec { + use std::collections::BTreeMap; + + type EdgeKey = (u32, Option); + + // First, deduplicate: for each (edge_key, fault_id), keep only one entry. + // Multiple components from the same fault_id on the same edge just confirm + // that the fault affects this edge -- don't double-count the probability. + let mut per_fault: BTreeMap<(EdgeKey, usize), MatchingEdge> = BTreeMap::new(); + + for edge in edges { + let key = match edge.node2 { + Some(n2) if edge.node1 > n2 => (n2, Some(edge.node1)), + _ => (edge.node1, edge.node2), + }; + let fault_key = (key, edge.fault_id); + // First occurrence of this (edge, fault_id) wins + per_fault.entry(fault_key).or_insert(MatchingEdge { + node1: key.0, + node2: key.1, + ..edge + }); + } + + // Now merge across different fault_ids for the same edge pair + let mut merged: BTreeMap = BTreeMap::new(); + + for ((edge_key, _fault_id), edge) in per_fault { + if let Some(existing) = merged.get_mut(&edge_key) { + // Independent combination: p_ab = p_a*(1-p_b) + p_b*(1-p_a) + let p_a = existing.probability; + let p_b = edge.probability; + let p_combined = p_a * (1.0 - p_b) + p_b * (1.0 - p_a); + existing.probability = p_combined; + existing.weight = if p_combined > 0.0 && p_combined < 1.0 { + ((1.0 - p_combined) / p_combined).ln() + } else if p_combined >= 1.0 { + 0.0 + } else { + 1e6 + }; + + // Keep the first edge's observables (matching PyMatching's + // INDEPENDENT strategy). If observables differ between parallel + // edges on the same node pair, the code has distance 2. + } else { + merged.insert(edge_key, edge); + } + } + + merged.into_values().collect() + } +} + +/// Generic wrapper that combines any [`Decoder`] with a [`DemCheckMatrix`] +/// to implement [`ObservableDecoder`]. +/// +/// This is the proper way to use check-matrix decoders (BP+OSD, `UnionFind`, +/// `RelayBP`, etc.) in a sample+decode loop. The wrapper: +/// 1. Passes the syndrome to the inner decoder +/// 2. Gets back a correction vector +/// 3. Multiplies by the observable matrix to get the observable prediction +/// +/// # Example +/// +/// ```ignore +/// use pecos_decoder_core::dem::{DemCheckMatrix, CheckMatrixObservableDecoder}; +/// +/// let dcm = DemCheckMatrix::from_dem_str(dem_str)?; +/// let inner_decoder = /* create BP+OSD from dcm.check_matrix */; +/// let mut decoder = CheckMatrixObservableDecoder::new(inner_decoder, dcm); +/// let mask = decoder.decode_to_observables(&syndrome)?; +/// ``` +pub struct CheckMatrixObservableDecoder { + /// The inner check-matrix decoder. + pub decoder: D, + /// The DEM check matrix (holds observable matrix for prediction). + pub dem: DemCheckMatrix, + /// Reusable syndrome buffer (avoids per-shot ndarray allocation). + syndrome_arr: ndarray::Array1, +} + +impl CheckMatrixObservableDecoder { + /// Create a new wrapper from a decoder and its DEM check matrix. + pub fn new(decoder: D, dem: DemCheckMatrix) -> Self { + let len = dem.num_detectors; + Self { + decoder, + dem, + syndrome_arr: ndarray::Array1::zeros(len), + } + } +} + +impl super::ObservableDecoder for CheckMatrixObservableDecoder +where + D: super::Decoder, +{ + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + use super::DecodingResultTrait; + + // Copy syndrome into reusable buffer (no allocation after first call) + let len = syndrome.len(); + if self.syndrome_arr.len() != len { + self.syndrome_arr = ndarray::Array1::zeros(len); + } + self.syndrome_arr + .as_slice_mut() + .unwrap() + .copy_from_slice(syndrome); + let result = self + .decoder + .decode(&self.syndrome_arr.view()) + .map_err(|e| DecoderError::DecodingFailed(e.to_string()))?; + + let correction = result.correction(); + Ok(self.dem.observables_mask_from_correction(correction)) + } +} + +/// Detector coordinate parsed from a DEM `detector(x, y, t) D_i` line. +#[derive(Debug, Clone)] +pub struct DetectorCoord { + /// Detector ID. + pub id: u32, + /// Coordinates (typically x, y, t for surface codes). + pub coords: Vec, +} + +/// Parse detector coordinates from a DEM string. +/// +/// Returns a list of `DetectorCoord` for each `detector(...)` declaration. +#[must_use] +pub fn parse_detector_coords(dem: &str) -> Vec { + let mut result = Vec::new(); + for line in dem.lines() { + let line = line.trim(); + if !line.starts_with("detector(") { + continue; + } + if let Some(close) = line.find(')') { + let coord_str = &line[9..close]; + let coords: Vec = coord_str + .split(',') + .filter_map(|s| s.trim().parse().ok()) + .collect(); + // Find D_i after the closing paren + let rest = &line[close + 1..]; + for token in rest.split_whitespace() { + if let Some(d_str) = token.strip_prefix('D') + && let Ok(id) = d_str.parse::() + { + result.push(DetectorCoord { + id, + coords: coords.clone(), + }); + } + } + } + } + result +} + /// Information about a detector error model #[derive(Debug, Clone, PartialEq)] pub struct DemInfo { @@ -301,6 +816,63 @@ mod tests { assert_eq!(observables, 2); // L0 and L1 } + #[test] + fn test_dem_check_matrix_basic() { + let dem = "error(0.01) D0 D1 L0\nerror(0.02) D1 D2\nerror(0.03) D0 D2 L0"; + let dcm = DemCheckMatrix::from_dem_str(dem).unwrap(); + + assert_eq!(dcm.num_detectors, 3); + assert_eq!(dcm.num_observables, 1); + assert_eq!(dcm.num_mechanisms, 3); + assert_eq!(dcm.error_priors, vec![0.01, 0.02, 0.03]); + + // Check matrix: mechanism 0 -> D0,D1; mechanism 1 -> D1,D2; mechanism 2 -> D0,D2 + assert_eq!(dcm.check_matrix[[0, 0]], 1); // D0, mech 0 + assert_eq!(dcm.check_matrix[[1, 0]], 1); // D1, mech 0 + assert_eq!(dcm.check_matrix[[2, 0]], 0); // D2, mech 0 + assert_eq!(dcm.check_matrix[[0, 1]], 0); // D0, mech 1 + assert_eq!(dcm.check_matrix[[1, 1]], 1); // D1, mech 1 + assert_eq!(dcm.check_matrix[[2, 1]], 1); // D2, mech 1 + + // Observable matrix: mechanism 0 -> L0; mechanism 1 -> none; mechanism 2 -> L0 + assert_eq!(dcm.observable_matrix[[0, 0]], 1); + assert_eq!(dcm.observable_matrix[[0, 1]], 0); + assert_eq!(dcm.observable_matrix[[0, 2]], 1); + } + + #[test] + fn test_dem_check_matrix_observables_from_correction() { + let dem = "error(0.01) D0 L0\nerror(0.01) D1 L1\nerror(0.01) D0 D1 L0 L1"; + let dcm = DemCheckMatrix::from_dem_str(dem).unwrap(); + + // Correction activates mechanism 0 -> L0 flips + assert_eq!(dcm.observables_mask_from_correction(&[1, 0, 0]), 0b01); + // Correction activates mechanism 2 -> L0 and L1 flip + assert_eq!(dcm.observables_mask_from_correction(&[0, 0, 1]), 0b11); + // Correction activates mechanisms 0 and 2 -> L0 xor L0 = 0, L1 flips + assert_eq!(dcm.observables_mask_from_correction(&[1, 0, 1]), 0b10); + } + + #[test] + fn test_dem_check_matrix_decomposed() { + // Decomposed mechanism: D0 ^ D1 means XOR + let dem = "error(0.01) D0 D1 ^ D1 D2"; + let dcm = DemCheckMatrix::from_dem_str(dem).unwrap(); + + // D1 appears in both components -> XOR cancels it + assert_eq!(dcm.check_matrix[[0, 0]], 1); // D0 + assert_eq!(dcm.check_matrix[[1, 0]], 0); // D1 cancels + assert_eq!(dcm.check_matrix[[2, 0]], 1); // D2 + } + + #[test] + fn test_dem_check_matrix_empty() { + let dem = ""; + let dcm = DemCheckMatrix::from_dem_str(dem).unwrap(); + assert_eq!(dcm.num_mechanisms, 0); + assert_eq!(dcm.num_detectors, 0); + } + #[test] fn test_dem_config_builder() { let config = DemConfigBuilder::new() diff --git a/crates/pecos-decoder-core/src/ensemble.rs b/crates/pecos-decoder-core/src/ensemble.rs new file mode 100644 index 000000000..c969f22c3 --- /dev/null +++ b/crates/pecos-decoder-core/src/ensemble.rs @@ -0,0 +1,270 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Multi-decoder ensemble with per-observable majority vote. +//! +//! Runs multiple decoders on the same syndrome, then combines their +//! predictions via (optionally weighted) majority vote on each +//! observable bit independently. + +use crate::ObservableDecoder; +use crate::errors::DecoderError; + +/// Voting strategy for combining decoder predictions. +#[derive(Debug, Clone)] +pub enum VotingStrategy { + /// Each decoder gets one vote. Ties go to 0 (no flip). + Majority, + /// Each decoder gets a weight. Higher weight = more influence. + /// Ties (equal total weight for 0 and 1) go to 0. + Weighted(Vec), +} + +/// Multi-decoder ensemble that votes on observable predictions. +/// +/// Each member decoder runs independently on the same syndrome, +/// then the ensemble combines their observable masks via majority +/// vote (per bit). +pub struct EnsembleDecoder { + decoders: Vec>, + strategy: VotingStrategy, + /// Reusable buffer for collecting predictions. + predictions: Vec, +} + +impl EnsembleDecoder { + /// Create an ensemble with uniform (majority) voting. + #[must_use] + pub fn new(decoders: Vec>) -> Self { + let n = decoders.len(); + Self { + decoders, + strategy: VotingStrategy::Majority, + predictions: Vec::with_capacity(n), + } + } + + /// Create an ensemble with weighted voting. + /// + /// # Panics + /// + /// Panics if `weights.len() != decoders.len()`. + #[must_use] + pub fn with_weights(decoders: Vec>, weights: Vec) -> Self { + assert_eq!( + decoders.len(), + weights.len(), + "number of weights must match number of decoders" + ); + let n = decoders.len(); + Self { + decoders, + strategy: VotingStrategy::Weighted(weights), + predictions: Vec::with_capacity(n), + } + } + + /// Number of decoders in the ensemble. + #[must_use] + pub fn len(&self) -> usize { + self.decoders.len() + } + + /// Whether the ensemble has no decoders. + #[must_use] + pub fn is_empty(&self) -> bool { + self.decoders.is_empty() + } +} + +impl ObservableDecoder for EnsembleDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + if self.decoders.is_empty() { + return Ok(0); + } + + // Collect predictions from all decoders. + self.predictions.clear(); + for decoder in &mut self.decoders { + self.predictions + .push(decoder.decode_to_observables(syndrome)?); + } + + // Vote on each observable bit independently. + let mut result = 0u64; + for bit in 0..64 { + let mask = 1u64 << bit; + + // Check if any decoder cares about this bit. + let any_set = self.predictions.iter().any(|&p| p & mask != 0); + if !any_set { + continue; + } + + let vote_for_flip = match &self.strategy { + VotingStrategy::Majority => { + let count = self.predictions.iter().filter(|&&p| p & mask != 0).count(); + // Strict majority: more than half must vote flip. + count * 2 > self.decoders.len() + } + VotingStrategy::Weighted(weights) => { + let mut weight_flip = 0.0; + let mut weight_no_flip = 0.0; + for (i, &pred) in self.predictions.iter().enumerate() { + if pred & mask != 0 { + weight_flip += weights[i]; + } else { + weight_no_flip += weights[i]; + } + } + weight_flip > weight_no_flip + } + }; + + if vote_for_flip { + result |= mask; + } + } + + Ok(result) + } +} + +/// Thread-safe ensemble decoder that decodes K members in parallel using rayon. +/// +/// Same majority-vote logic as `EnsembleDecoder` but runs all members +/// concurrently. Requires inner decoders to be `Send`. +pub struct ParallelEnsembleDecoder { + decoders: Vec>, +} + +impl ParallelEnsembleDecoder { + /// Create a parallel ensemble with majority voting. + #[must_use] + pub fn new(decoders: Vec>) -> Self { + Self { decoders } + } + + /// Number of decoders. + #[must_use] + pub fn len(&self) -> usize { + self.decoders.len() + } + + /// Whether the ensemble is empty. + #[must_use] + pub fn is_empty(&self) -> bool { + self.decoders.is_empty() + } +} + +impl ObservableDecoder for ParallelEnsembleDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + use rayon::prelude::*; + + if self.decoders.is_empty() { + return Ok(0); + } + + // Decode all members in parallel. + let predictions: Result, DecoderError> = self + .decoders + .par_iter_mut() + .map(|decoder| decoder.decode_to_observables(syndrome)) + .collect(); + let predictions = predictions?; + + // Majority vote. + let half = predictions.len() / 2; + let mut result = 0u64; + for bit in 0..64 { + let mask = 1u64 << bit; + let count = predictions.iter().filter(|&&p| p & mask != 0).count(); + if count > half { + result |= mask; + } + } + Ok(result) + } +} + +#[cfg(test)] +mod tests { + use super::*; + + /// Fake decoder that always returns a fixed observable mask. + struct FixedDecoder(u64); + + impl ObservableDecoder for FixedDecoder { + fn decode_to_observables(&mut self, _syndrome: &[u8]) -> Result { + Ok(self.0) + } + } + + #[test] + fn test_majority_unanimous() { + let decoders: Vec> = vec![ + Box::new(FixedDecoder(0b101)), + Box::new(FixedDecoder(0b101)), + Box::new(FixedDecoder(0b101)), + ]; + let mut ensemble = EnsembleDecoder::new(decoders); + assert_eq!(ensemble.decode_to_observables(&[]).unwrap(), 0b101); + } + + #[test] + fn test_majority_split() { + let decoders: Vec> = vec![ + Box::new(FixedDecoder(0b11)), + Box::new(FixedDecoder(0b01)), + Box::new(FixedDecoder(0b01)), + ]; + let mut ensemble = EnsembleDecoder::new(decoders); + // Bit 0: 3/3 vote flip -> flip. Bit 1: 1/3 vote flip -> no flip. + assert_eq!(ensemble.decode_to_observables(&[]).unwrap(), 0b01); + } + + #[test] + fn test_majority_tie_goes_to_zero() { + // With 2 decoders, need >50% for flip. 1/2 is not >50%. + let decoders: Vec> = + vec![Box::new(FixedDecoder(1)), Box::new(FixedDecoder(0))]; + let mut ensemble = EnsembleDecoder::new(decoders); + assert_eq!(ensemble.decode_to_observables(&[]).unwrap(), 0); + } + + #[test] + fn test_weighted_vote() { + let decoders: Vec> = vec![ + Box::new(FixedDecoder(1)), // votes flip, weight 3.0 + Box::new(FixedDecoder(0)), // votes no flip, weight 1.0 + Box::new(FixedDecoder(0)), // votes no flip, weight 1.0 + ]; + let mut ensemble = EnsembleDecoder::with_weights(decoders, vec![3.0, 1.0, 1.0]); + // Weight for flip: 3.0, weight for no flip: 2.0. Flip wins. + assert_eq!(ensemble.decode_to_observables(&[]).unwrap(), 1); + } + + #[test] + fn test_empty_ensemble() { + let mut ensemble = EnsembleDecoder::new(vec![]); + assert_eq!(ensemble.decode_to_observables(&[]).unwrap(), 0); + assert!(ensemble.is_empty()); + } + + #[test] + fn test_single_decoder() { + let decoders: Vec> = vec![Box::new(FixedDecoder(42))]; + let mut ensemble = EnsembleDecoder::new(decoders); + assert_eq!(ensemble.decode_to_observables(&[]).unwrap(), 42); + } +} diff --git a/crates/pecos-decoder-core/src/erasure.rs b/crates/pecos-decoder-core/src/erasure.rs new file mode 100644 index 000000000..0fb661a96 --- /dev/null +++ b/crates/pecos-decoder-core/src/erasure.rs @@ -0,0 +1,48 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Erasure-aware observable decoder for neutral atom QEC. +//! +//! Neutral atoms have a dominant erasure channel: atom loss is detectable +//! via fluorescence, giving the decoder side-channel information about +//! which qubits were lost. This raises the surface code threshold from +//! ~1% to ~4%. +//! +//! The decoder receives: +//! - A syndrome (detection events) +//! - A list of erased qubit/edge indices (known error locations) +//! +//! Erased edges are set to zero weight (certain error) during matching, +//! guiding the decoder to incorporate them into the correction. + +use crate::errors::DecoderError; + +/// Trait for decoders that can handle erasure information alongside the syndrome. +/// +/// For neutral atoms, erasures come from atom loss detection. The decoder +/// sets erased edge weights to zero (guaranteed error) and finds the +/// minimum-weight correction incorporating the known erasures. +pub trait ObservableErasureDecoder { + /// Decode a syndrome with erasure side-channel information. + /// + /// `erasure_edges`: indices of edges (error mechanisms) known to have + /// fired. These are set to zero weight during matching. + /// + /// # Errors + /// + /// Returns `DecoderError` if decoding fails. + fn decode_with_erasures( + &mut self, + syndrome: &[u8], + erasure_edges: &[usize], + ) -> Result; +} diff --git a/crates/pecos-decoder-core/src/ghost_protocol.rs b/crates/pecos-decoder-core/src/ghost_protocol.rs new file mode 100644 index 000000000..dc3abb8dc --- /dev/null +++ b/crates/pecos-decoder-core/src/ghost_protocol.rs @@ -0,0 +1,349 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Ghost protocol for modular per-qubit decoding across transversal gates. +//! +//! Based on Turner et al. (arXiv:2505.23567): decomposes order-3 +//! hyperedges from transversal CNOT into per-qubit ghost edges. +//! Each qubit's decoder runs independently with sparse message passing, +//! enabling scalable decoding of many logical qubits. +//! +//! # Algorithm +//! +//! 1. Decompose cross-qubit hyperedges into ghost edge + ghost singleton +//! 2. Each qubit decoded independently with ghost edges in its graph +//! 3. If matching includes a ghost edge: refine syndrome, message partner +//! 4. Partner flips its ghost singleton defect, re-decodes +//! 5. Iterate until convergence (no new ghost edges detected) +//! +//! # References +//! +//! - Turner et al. "Scalable decoding protocols for fast transversal +//! logic in the surface code" (arXiv:2505.23567, PRX Quantum 2026) +//! - Cain et al. "Fast correlated decoding of transversal logical +//! algorithms" (arXiv:2505.13587) + + +/// A ghost edge: fragment of a cross-qubit hyperedge. +/// +/// When a measurement error before a transversal CNOT creates a +/// 3-detector hyperedge spanning two qubits, it decomposes into: +/// - `ghost_edge`: time-like edge within one qubit (connects two +/// detectors on the same qubit across the gate boundary) +/// - `ghost_singleton`: boundary edge on the partner qubit (flips +/// one detector on the partner) +#[derive(Debug, Clone)] +pub struct GhostEdge { + /// Qubit (patch) that owns this ghost edge. + pub owner_qubit: usize, + /// Local detector index for the first endpoint. + pub det_a: u32, + /// Local detector index for the second endpoint. + pub det_b: u32, + /// Partner qubit that owns the ghost singleton. + pub partner_qubit: usize, + /// Local detector index of the ghost singleton on the partner. + pub partner_det: u32, + /// Edge weight (log-likelihood ratio). + pub weight: f64, +} + +/// Ghost protocol state for iterative decoding. +/// +/// Tracks ghost edges, messages between per-qubit decoders, and +/// syndrome refinement state. Created once per circuit structure, +/// reused across shots. +pub struct GhostProtocolState { + /// Ghost edges grouped by owner qubit. + pub ghost_edges: Vec>, + /// Number of logical qubits (patches). + pub num_qubits: usize, + /// Maximum iterations before giving up. + pub max_iterations: usize, +} + +impl GhostProtocolState { + /// Create ghost protocol state for a circuit. + /// + /// `ghost_edges`: all ghost edges, will be grouped by owner qubit. + /// `num_qubits`: number of logical qubits. + #[must_use] + pub fn new(ghost_edges: Vec, num_qubits: usize) -> Self { + let mut grouped = vec![Vec::new(); num_qubits]; + for ge in ghost_edges { + if ge.owner_qubit < num_qubits { + grouped[ge.owner_qubit].push(ge); + } + } + Self { + ghost_edges: grouped, + num_qubits, + max_iterations: 10, + } + } + + /// Number of ghost edges for a qubit. + #[must_use] + pub fn num_ghost_edges(&self, qubit: usize) -> usize { + self.ghost_edges.get(qubit).map_or(0, std::vec::Vec::len) + } + + /// Total ghost edges across all qubits. + #[must_use] + pub fn total_ghost_edges(&self) -> usize { + self.ghost_edges.iter().map(std::vec::Vec::len).sum() + } +} + +/// Message from one qubit's decoder to another. +/// +/// When a ghost edge is detected in the matching, the owner sends +/// this message to the partner: "flip your ghost singleton defect." +#[derive(Debug, Clone)] +pub struct GhostMessage { + /// Target qubit. + pub target_qubit: usize, + /// Detector to flip on the target. + pub flip_detector: u32, +} + +/// Extract ghost edges from a DEM at transversal CNOT boundaries. +/// +/// Identifies 3-detector mechanisms where: +/// - 2 detectors are on one qubit (the ghost edge endpoints) +/// - 1 detector is on another qubit (the ghost singleton) +/// +/// The qubit assignment comes from the detector's spatial coordinates +/// and the stabilizer coordinate map. +/// +/// Returns the ghost edges for the ghost protocol. +/// Extract ghost edges from a DEM by identifying 3-detector hyperedges +/// and decomposing them by qubit ownership. +/// +/// For each 3-detector mechanism where 2 detectors are on one qubit +/// and 1 is on another: +/// - `ghost_edge` = the 2-detector pair (within one qubit) +/// - `ghost_singleton` = the lone detector (on the partner qubit) +#[must_use] +pub fn extract_ghost_edges_from_dem( + dem_str: &str, + stab_coords: &crate::observable_subgraph::StabCoords, +) -> Vec { + use crate::observable_subgraph::classify_detector; + use std::collections::BTreeMap; + + // Parse detector coordinates + let det_coords = crate::dem::parse_detector_coords(dem_str); + let mut coord_map: BTreeMap> = BTreeMap::new(); + for dc in &det_coords { + coord_map.insert(dc.id as usize, dc.coords.clone()); + } + + // Classify detectors by qubit + let mut det_qubit: BTreeMap = BTreeMap::new(); + for (&d, coords) in &coord_map { + if coords.len() >= 2 + && let Some(group) = classify_detector(coords[0], coords[1], stab_coords) { + det_qubit.insert(d, group.qubit_idx); + } + } + + let mut ghost_edges = Vec::new(); + + for line in dem_str.lines() { + let line = line.trim(); + if !line.starts_with("error(") { + continue; + } + + let close = match line.find(')') { + Some(i) => i, + None => continue, + }; + + let prob: f64 = match line[6..close].parse() { + Ok(p) => p, + Err(_) => continue, + }; + + let mut dets = Vec::new(); + for token in line[close + 1..].split_whitespace() { + if let Some(d_str) = token.strip_prefix('D') + && let Ok(d) = d_str.parse::() { + dets.push(d); + } + } + + if dets.len() != 3 { + continue; + } + + let qs: Vec> = dets.iter().map(|d| det_qubit.get(d).copied()).collect(); + + if qs.iter().any(std::option::Option::is_none) { + continue; + } + let qs: Vec = qs.into_iter().flatten().collect(); + + let weight = if prob < 1.0 && prob > 0.0 { + ((1.0 - prob) / prob).ln() + } else { + 0.0 + }; + + // Decompose: 2 on one qubit (ghost edge), 1 on another (singleton) + let decompose = + |owner_q: usize, a: usize, b: usize, partner_q: usize, c: usize| GhostEdge { + owner_qubit: owner_q, + det_a: a as u32, + det_b: b as u32, + partner_qubit: partner_q, + partner_det: c as u32, + weight, + }; + + if qs[0] == qs[1] && qs[0] != qs[2] { + ghost_edges.push(decompose(qs[0], dets[0], dets[1], qs[2], dets[2])); + } else if qs[0] == qs[2] && qs[0] != qs[1] { + ghost_edges.push(decompose(qs[0], dets[0], dets[2], qs[1], dets[1])); + } else if qs[1] == qs[2] && qs[1] != qs[0] { + ghost_edges.push(decompose(qs[1], dets[1], dets[2], qs[0], dets[0])); + } + } + + ghost_edges +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_ghost_protocol_state() { + let edges = vec![ + GhostEdge { + owner_qubit: 0, + det_a: 5, + det_b: 10, + partner_qubit: 1, + partner_det: 7, + weight: 3.0, + }, + GhostEdge { + owner_qubit: 1, + det_a: 3, + det_b: 8, + partner_qubit: 0, + partner_det: 12, + weight: 3.0, + }, + ]; + + let state = GhostProtocolState::new(edges, 2); + assert_eq!(state.num_qubits, 2); + assert_eq!(state.num_ghost_edges(0), 1); + assert_eq!(state.num_ghost_edges(1), 1); + assert_eq!(state.total_ghost_edges(), 2); + } + + #[test] + fn test_empty_ghost_protocol() { + let state = GhostProtocolState::new(Vec::new(), 4); + assert_eq!(state.total_ghost_edges(), 0); + } + + #[test] + fn test_extract_ghost_edges_from_synthetic_dem() { + use crate::observable_subgraph::QubitStabCoords; + + // Two qubits: qubit 0 has X-stab at (1,1) and Z-stab at (3,1), + // qubit 1 has X-stab at (7,1) and Z-stab at (9,1). + let stab_coords = vec![ + QubitStabCoords { + x_positions: vec![(1.0, 1.0)], + z_positions: vec![(3.0, 1.0)], + }, + QubitStabCoords { + x_positions: vec![(7.0, 1.0)], + z_positions: vec![(9.0, 1.0)], + }, + ]; + + // DEM with: + // - D0 at (1,1,0) -> qubit 0 (X-stab) + // - D1 at (3,1,0) -> qubit 0 (Z-stab) + // - D2 at (7,1,0) -> qubit 1 (X-stab) + // - 3-body error: D0 D1 D2 (2 on qubit 0, 1 on qubit 1) + // - 2-body error: D0 D1 (same qubit, no ghost edge) + let dem = "\ + detector(1, 1, 0) D0\n\ + detector(3, 1, 0) D1\n\ + detector(7, 1, 0) D2\n\ + error(0.01) D0 D1 D2\n\ + error(0.02) D0 D1\n"; + + let edges = extract_ghost_edges_from_dem(dem, &stab_coords); + + // Should extract exactly 1 ghost edge from the 3-body mechanism + assert_eq!(edges.len(), 1); + + let e = &edges[0]; + assert_eq!(e.owner_qubit, 0); // D0 and D1 are on qubit 0 + assert_eq!(e.det_a, 0); + assert_eq!(e.det_b, 1); + assert_eq!(e.partner_qubit, 1); // D2 is on qubit 1 + assert_eq!(e.partner_det, 2); + + // Weight should be ln((1 - 0.01) / 0.01) ≈ 4.595 + assert!((e.weight - 4.595).abs() < 0.01); + } + + #[test] + fn test_extract_no_ghost_edges_graphlike_dem() { + use crate::observable_subgraph::QubitStabCoords; + + let stab_coords = vec![QubitStabCoords { + x_positions: vec![(1.0, 1.0)], + z_positions: vec![(3.0, 1.0)], + }]; + + // Only 2-body errors -> no ghost edges + let dem = "\ + detector(1, 1, 0) D0\n\ + detector(3, 1, 0) D1\n\ + error(0.01) D0 D1\n\ + error(0.005) D0\n"; + + let edges = extract_ghost_edges_from_dem(dem, &stab_coords); + assert_eq!(edges.len(), 0); + } + + #[test] + fn test_extract_three_same_qubit_no_ghost() { + use crate::observable_subgraph::QubitStabCoords; + + let stab_coords = vec![QubitStabCoords { + x_positions: vec![(1.0, 1.0), (1.0, 3.0)], + z_positions: vec![(3.0, 1.0)], + }]; + + // All 3 detectors on same qubit -> no decomposition + let dem = "\ + detector(1, 1, 0) D0\n\ + detector(1, 3, 0) D1\n\ + detector(3, 1, 0) D2\n\ + error(0.01) D0 D1 D2\n"; + + let edges = extract_ghost_edges_from_dem(dem, &stab_coords); + assert_eq!(edges.len(), 0); + } +} diff --git a/crates/pecos-decoder-core/src/k_mwpm.rs b/crates/pecos-decoder-core/src/k_mwpm.rs new file mode 100644 index 000000000..8aea6bd03 --- /dev/null +++ b/crates/pecos-decoder-core/src/k_mwpm.rs @@ -0,0 +1,277 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! K-MWPM decoder: enumerate K lowest-weight matchings, majority vote. +//! +//! Based on the Chegireddy-Hamacher algorithm adapted for QEC by +//! Mao Lin (Phys. Rev. A 112, 042436, 2025; arXiv:2510.06531). +//! +//! Builds a "decoding tree" where each branch removes one matched edge +//! from the parent and re-matches. The K lowest-weight matchings give +//! K observable predictions; majority vote selects the final answer. +//! +//! Works with any `MatchingDecoder` backend (UF, Fusion Blossom). + +use crate::ObservableDecoder; +use crate::correlated_decoder::EdgeTrackingDecoder; +use crate::errors::DecoderError; +use std::cmp::Reverse; +use std::collections::BinaryHeap; + +/// Configuration for the K-MWPM decoder. +#[derive(Debug, Clone, Copy)] +pub struct KMwpmConfig { + /// Number of matchings to enumerate. Default 10. + pub k: usize, +} + +impl Default for KMwpmConfig { + fn default() -> Self { + Self { k: 10 } + } +} + +/// One node in the decoding tree. +struct TreeNode { + /// Matched edge indices from the MWPM solve. + matched_edges: Vec, + /// Edges that were removed (set to infinity) for this branch. + removed_edges: Vec, + /// Syndrome modifications: detector indices to flip. + flipped_detectors: Vec, + /// Index in `matched_edges` up to which edges are "committed" (removed). + commit_idx: usize, +} + +/// K-MWPM decoder wrapping any `EdgeTrackingDecoder`. +pub struct KMwpmDecoder { + decoder: D, + config: KMwpmConfig, + num_edges: usize, +} + +impl KMwpmDecoder { + /// Create from an existing decoder. + pub fn new(decoder: D, config: KMwpmConfig) -> Self { + let num_edges = decoder.num_edges(); + Self { + decoder, + config, + num_edges, + } + } +} + +impl ObservableDecoder for KMwpmDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + let k = self.config.k; + + // First matching: standard MWPM. + let (obs1, edges1) = self.decoder.decode_with_matching(syndrome)?; + + if edges1.is_empty() { + return Ok(obs1); + } + + // Collect K matchings via decoding tree. + let mut predictions: Vec = vec![obs1]; + + // Priority queue of tree nodes to expand (by weight, lowest first). + let mut pq: BinaryHeap<(Reverse, usize)> = BinaryHeap::new(); + let mut nodes: Vec = Vec::new(); + + let root = TreeNode { + matched_edges: edges1, + removed_edges: Vec::new(), + flipped_detectors: Vec::new(), + commit_idx: 0, + }; + nodes.push(root); + pq.push((Reverse(0), 0)); // Weight 0 for expansion priority (children will have real weights) + + while predictions.len() < k { + let (_, node_idx) = match pq.pop() { + Some(item) => item, + None => break, // No more candidates + }; + + // Expand this node: for each matched edge from commit_idx onward, + // create a child that removes that edge and re-matches. + let (matched_edges, removed_edges, flipped_detectors, commit_idx) = { + let node = &nodes[node_idx]; + ( + node.matched_edges.clone(), + node.removed_edges.clone(), + node.flipped_detectors.clone(), + node.commit_idx, + ) + }; + + for j in commit_idx..matched_edges.len() { + // Build modified weights: removed edges get infinite weight. + let mut weights = vec![0.0f64; self.num_edges]; + // Start with original weights for all edges. + for e in 0..self.num_edges { + weights[e] = self.decoder.edge_weight(e); + } + // Remove previously removed edges. + for &re in &removed_edges { + weights[re] = 1e10; + } + // Remove edges e_{commit_idx}..e_j (inclusive). + for &re in &matched_edges[commit_idx..=j] { + weights[re] = 1e10; + } + + // Build modified syndrome: flip endpoints of committed edges. + let mut syn_mod = syndrome.to_vec(); + for &det in &flipped_detectors { + if det < syn_mod.len() { + syn_mod[det] ^= 1; + } + } + // Also flip endpoints of edges commit_idx..j-1 (newly committed). + let num_det = self.decoder.num_detectors(); + for &edge_idx in &matched_edges[commit_idx..j] { + let n1 = self.decoder.edge_node1(edge_idx) as usize; + let n2 = self.decoder.edge_node2(edge_idx) as usize; + if n1 < syn_mod.len() && n1 < num_det { + syn_mod[n1] ^= 1; + } + if n2 < syn_mod.len() && n2 < num_det { + syn_mod[n2] ^= 1; + } + } + + // Re-match with modified weights and syndrome. + let result = self.decoder.decode_with_weights(&syn_mod, &weights); + if let Ok((child_obs, child_edges)) = result { + // The full observable includes committed edges' observables. + let mut full_obs = child_obs; + for &edge_idx in &matched_edges[..j] { + full_obs ^= self.decoder.edge_obs_mask(edge_idx); + } + + // Build child's removed set and flipped set. + let mut child_removed = removed_edges.clone(); + for &re in &matched_edges[commit_idx..=j] { + child_removed.push(re); + } + let mut child_flipped = flipped_detectors.clone(); + for &edge_idx in &matched_edges[commit_idx..j] { + let n1 = self.decoder.edge_node1(edge_idx) as usize; + let n2 = self.decoder.edge_node2(edge_idx) as usize; + if n1 < num_det { + child_flipped.push(n1); + } + if n2 < num_det { + child_flipped.push(n2); + } + } + + predictions.push(full_obs); + + let child_node = TreeNode { + matched_edges: child_edges, + removed_edges: child_removed, + flipped_detectors: child_flipped, + commit_idx: 0, + }; + let child_idx = nodes.len(); + nodes.push(child_node); + // Priority by expansion order (breadth-first). + pq.push((Reverse(child_idx as u64), child_idx)); + } + + if predictions.len() >= k { + break; + } + } + } + + // Majority vote across K predictions. + let half = predictions.len() / 2; + let mut result = 0u64; + for bit in 0..64u32 { + let mask = 1u64 << bit; + let count = predictions.iter().filter(|&&p| p & mask != 0).count(); + if count > half { + result |= mask; + } + } + Ok(result) + } +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::errors::DecoderError; + + /// Trivial decoder: always returns obs=0, no matched edges. + struct TrivialDecoder { + num_edges: usize, + } + + impl crate::correlated_decoder::MatchingDecoder for TrivialDecoder { + fn decode_with_matching( + &mut self, + _syndrome: &[u8], + ) -> Result<(u64, Vec), DecoderError> { + Ok((0, Vec::new())) + } + fn decode_with_weights( + &mut self, + _syndrome: &[u8], + _weights: &[f64], + ) -> Result<(u64, Vec), DecoderError> { + Ok((0, Vec::new())) + } + fn num_edges(&self) -> usize { + self.num_edges + } + } + + impl crate::correlated_decoder::EdgeTrackingDecoder for TrivialDecoder { + fn edge_node1(&self, _: usize) -> u32 { + 0 + } + fn edge_node2(&self, _: usize) -> u32 { + 1 + } + fn edge_weight(&self, _: usize) -> f64 { + 1.0 + } + fn edge_obs_mask(&self, _: usize) -> u64 { + 0 + } + fn num_detectors(&self) -> usize { + 2 + } + } + + #[test] + fn test_k_mwpm_zero_syndrome() { + let decoder = TrivialDecoder { num_edges: 2 }; + let mut k_dec = KMwpmDecoder::new(decoder, KMwpmConfig { k: 5 }); + let obs = k_dec.decode_to_observables(&[0, 0]).unwrap(); + assert_eq!(obs, 0); + } + + #[test] + fn test_k_mwpm_k1() { + let decoder = TrivialDecoder { num_edges: 2 }; + let mut k_dec = KMwpmDecoder::new(decoder, KMwpmConfig { k: 1 }); + let obs = k_dec.decode_to_observables(&[0, 0]).unwrap(); + assert_eq!(obs, 0); + } +} diff --git a/crates/pecos-decoder-core/src/lib.rs b/crates/pecos-decoder-core/src/lib.rs index d7d47fe1b..293e33327 100644 --- a/crates/pecos-decoder-core/src/lib.rs +++ b/crates/pecos-decoder-core/src/lib.rs @@ -11,12 +11,33 @@ //! - `matrix` - Common matrix types and check matrix traits //! - `dem` - Detector error model traits and utilities +pub mod adaptive; pub mod advanced; +pub mod bp_matching; +pub mod committed_osd; pub mod config; +pub mod correlated_decoder; +pub mod correlated_reweighting; +pub mod correlation_table; +pub mod decode_budget; pub mod dem; +pub mod ensemble; +pub mod erasure; pub mod errors; +pub mod ghost_protocol; +pub mod k_mwpm; +pub mod logical_algorithm; pub mod matrix; +pub mod multi_decoder; +pub mod observable_subgraph; +pub mod pauli_frame; +pub mod perturbed; +pub mod preprocessor; pub mod results; +pub mod streaming; +pub mod telemetry; +pub mod two_pass_decoder; +pub mod windowed_osd; use ndarray::ArrayView1; @@ -28,7 +49,10 @@ pub use advanced::{ pub use config::{ BatchConfig, ConfigBuilder, DecoderConfig, DecodingMethod, PerformanceConfig, SolverType, }; -pub use dem::{DemConfig, DemConfigBuilder, DemDecoder, DemInfo}; +pub use dem::{ + CheckMatrixObservableDecoder, DemCheckMatrix, DemConfig, DemConfigBuilder, DemDecoder, DemInfo, + DemMatchingGraph, DetectorCoord, MatchingEdge, parse_detector_coords, +}; pub use errors::{ConfigError, DecoderError, ErrorConvert, GraphError, MatrixError}; pub use matrix::{CheckMatrixConfig, CheckMatrixDecoder, SparseCheckMatrix}; pub use results::{ @@ -123,6 +147,46 @@ pub trait BatchDecoder: Decoder { -> Result, Self::Error>; } +// ============================================================================ +// Observable Decoder Trait (for sample+decode loops) +// ============================================================================ + +/// Minimal trait for decoders used in threshold estimation loops. +/// +/// Takes a detection event syndrome (dense `&[u8]`), returns the predicted +/// observable flip mask. This is the only interface the sample+decode +/// orchestrator needs -- it doesn't care about decoder internals, weights, +/// convergence, or matched edges. +pub trait ObservableDecoder { + /// Decode a dense syndrome and return predicted observable flips as a bitmask. + /// + /// Bit `i` of the returned value is 1 if observable `i` is predicted to flip. + /// + /// # Errors + /// + /// Returns [`DecoderError`] if decoding fails. + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result; + + /// Batch decode: flat buffer of `num_shots × num_detectors` bytes. + /// Returns one `u64` observable mask per shot. + /// + /// Default: loops over shots calling `decode_to_observables`. + /// Override for decoders with native batch support (e.g. `PyMatching`). + fn decode_batch_to_observables( + &mut self, + shots: &[u8], + num_shots: usize, + num_detectors: usize, + ) -> Result, DecoderError> { + let mut results = Vec::with_capacity(num_shots); + for i in 0..num_shots { + let syn = &shots[i * num_detectors..(i + 1) * num_detectors]; + results.push(self.decode_to_observables(syn)?); + } + Ok(results) + } +} + // ============================================================================ // Re-exports // ============================================================================ diff --git a/crates/pecos-decoder-core/src/logical_algorithm.rs b/crates/pecos-decoder-core/src/logical_algorithm.rs new file mode 100644 index 000000000..d3587c026 --- /dev/null +++ b/crates/pecos-decoder-core/src/logical_algorithm.rs @@ -0,0 +1,1027 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Logical algorithm decoder for real-time QEC. +//! +//! Decodes logical algorithms (sequences of memory segments separated by +//! transversal gates) using the full-circuit DEM for accuracy, with +//! segment structure metadata for streaming and frame propagation. +//! +//! # Decoding Modes +//! +//! - **Full-circuit**: Uses the full DEM's OSD for maximum accuracy. +//! Equivalent to `ObservableSubgraphDecoder` on the full circuit. +//! - **Per-segment** (future streaming): Each segment decoded independently +//! with buffer overlap at gate boundaries. + +use crate::ObservableDecoder; +use crate::errors::DecoderError; + +/// One segment of a logical algorithm. +pub struct SegmentDescriptor { + /// Number of detectors in this segment's DEM. + pub num_detectors: usize, + /// Number of observables in this segment's DEM. + pub num_observables: usize, +} + +/// Gate at a segment boundary. +#[derive(Debug, Clone)] +pub enum BoundaryGate { + /// Transversal Hadamard: swaps X↔Z frame bits for a qubit. + Hadamard { x_obs_bit: u32, z_obs_bit: u32 }, + /// Transversal CNOT: propagates X forward, Z backward. + Cnot { + ctrl_x_bit: u32, + ctrl_z_bit: u32, + tgt_x_bit: u32, + tgt_z_bit: u32, + }, + /// Transversal S gate: X corrections induce Z corrections. + SGate { x_obs_bit: u32, z_obs_bit: u32 }, + /// T-gate via magic state injection (decision point). + /// + /// At this boundary, the decoder MUST produce a correction before + /// the hardware can proceed. The corrected measurement outcome + /// determines whether an S correction is applied: + /// corrected = `raw_measurement` XOR frame[`z_obs_bit`] + /// if corrected == 1: apply S gate on the data qubit + /// + /// This is a feed-forward decision point with a reaction time + /// deadline. The decoder's frame must be ready. + TGateInjection { + /// Observable bit for the data qubit's Z correction. + z_obs_bit: u32, + /// Observable bit for the ancilla's Z measurement. + ancilla_z_bit: u32, + }, +} + +/// Marks whether a segment boundary is a decision point. +/// +/// At decision points, the decoder must provide the Pauli frame +/// within the reaction time budget. At non-decision boundaries +/// (Clifford gates), the frame is metadata — no deadline. +impl BoundaryGate { + /// Whether this gate is a feed-forward decision point. + #[must_use] + pub fn is_decision_point(&self) -> bool { + matches!(self, Self::TGateInjection { .. }) + } +} + +/// Full description of a logical algorithm for decoding. +pub struct AlgorithmDescriptor { + /// Per-segment descriptors. + pub segments: Vec, + /// Gates at segment boundaries. `boundary_gates[i]` between segment i and i+1. + pub boundary_gates: Vec>, + /// Total number of observables. + pub num_observables: usize, +} + +/// Decoder for logical quantum algorithms. +/// +/// Wraps a full-circuit decoder (OSD) with segment metadata. The +/// segment structure enables: +/// - Tracking which gates occur at which point in the circuit +/// - Pauli frame propagation for T-gate/measurement corrections +/// - Future streaming mode with per-segment windowed decoding +/// +/// In the current implementation, `decode_shot` delegates to the +/// full-circuit OSD for maximum accuracy. The segment structure is +/// metadata for frame tracking and streaming (step 5). +pub struct LogicalAlgorithmDecoder { + /// Full-circuit decoder (OSD on the complete DEM). + full_decoder: Box, + /// Segment metadata for streaming/frame tracking. + segments: Vec, + /// Gates at segment boundaries. + boundary_gates: Vec>, + /// Total number of observables. + _num_observables: usize, +} + +impl LogicalAlgorithmDecoder { + /// Build from a full-circuit decoder and algorithm descriptor. + /// + /// The `full_decoder` is typically an `ObservableSubgraphDecoder` + /// built from the full circuit DEM. + #[must_use] + pub fn new( + full_decoder: Box, + descriptor: AlgorithmDescriptor, + ) -> Self { + Self { + full_decoder, + segments: descriptor.segments, + boundary_gates: descriptor.boundary_gates, + _num_observables: descriptor.num_observables, + } + } + + /// Decode one shot using the full-circuit decoder. + pub fn decode_shot(&mut self, syndrome: &[u8]) -> Result { + self.full_decoder.decode_to_observables(syndrome) + } + + /// Number of segments. + #[must_use] + pub fn num_segments(&self) -> usize { + self.segments.len() + } + + /// Total detectors across all segments. + #[must_use] + pub fn total_detectors(&self) -> usize { + self.segments.iter().map(|s| s.num_detectors).sum() + } + + /// Apply boundary gate to a Pauli frame. + /// Used when consuming the frame at logical operations. + pub fn apply_boundary_gate(frame: &mut u64, gate: &BoundaryGate) { + match gate { + BoundaryGate::Hadamard { + x_obs_bit, + z_obs_bit, + } => { + let x_set = (*frame >> x_obs_bit) & 1; + let z_set = (*frame >> z_obs_bit) & 1; + *frame &= !(1u64 << x_obs_bit); + *frame &= !(1u64 << z_obs_bit); + *frame |= z_set << x_obs_bit; + *frame |= x_set << z_obs_bit; + } + BoundaryGate::Cnot { + ctrl_x_bit, + ctrl_z_bit, + tgt_x_bit, + tgt_z_bit, + } => { + if (*frame >> ctrl_x_bit) & 1 != 0 { + *frame ^= 1u64 << tgt_x_bit; + } + if (*frame >> tgt_z_bit) & 1 != 0 { + *frame ^= 1u64 << ctrl_z_bit; + } + } + BoundaryGate::SGate { + x_obs_bit, + z_obs_bit, + } => { + if (*frame >> x_obs_bit) & 1 != 0 { + *frame ^= 1u64 << z_obs_bit; + } + } + BoundaryGate::TGateInjection { + z_obs_bit, + ancilla_z_bit, + } => { + // T-gate teleportation: CX(data, ancilla) + measure ancilla Z. + // The ancilla Z measurement outcome (corrected by frame) + // determines whether to apply S correction on data. + // + // Frame propagation: the ancilla's Z observable is folded + // into the data's Z observable. If the ancilla Z bit is + // set in the frame, flip the data's Z bit. + if (*frame >> ancilla_z_bit) & 1 != 0 { + *frame ^= 1u64 << z_obs_bit; + } + } + } + } +} + +impl ObservableDecoder for LogicalAlgorithmDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + self.decode_shot(syndrome) + } +} + +// ============================================================================ +// Streaming mode +// ============================================================================ + +/// Streaming wrapper for `LogicalAlgorithmDecoder`. +/// +/// Buffers syndrome data round-by-round. The full-circuit OSD decodes +/// the entire accumulated syndrome at `flush()` for maximum accuracy. +/// +/// The segment structure tracks which rounds belong to which segment. +/// At each segment boundary, the Pauli frame can be queried and +/// propagated through the boundary gate. +/// +/// # Usage +/// +/// ```ignore +/// let mut stream = StreamingLogicalDecoder::new(decoder, round_to_det_map); +/// +/// // Feed syndrome round by round +/// for (round, detectors) in syndrome_stream { +/// stream.feed_round(&detectors); +/// } +/// +/// // Decode at the end +/// let obs = stream.flush()?; +/// ``` +pub struct StreamingLogicalDecoder { + /// The underlying batch decoder (full-circuit OSD). + inner: LogicalAlgorithmDecoder, + /// Accumulated syndrome buffer (full circuit size). + syndrome: Vec, + /// Total detectors. + total_detectors: usize, + /// Rounds fed so far. + rounds_fed: usize, + /// Accumulated observable correction from last flush. + accumulated_obs: u64, +} + +impl StreamingLogicalDecoder { + /// Create from a `LogicalAlgorithmDecoder`. + #[must_use] + pub fn new(decoder: LogicalAlgorithmDecoder) -> Self { + let total = decoder.total_detectors(); + Self { + inner: decoder, + syndrome: vec![0u8; total], + total_detectors: total, + rounds_fed: 0, + accumulated_obs: 0, + } + } + + /// Feed one detection event into the syndrome buffer. + #[inline] + pub fn feed_detection(&mut self, detector_idx: usize, value: u8) { + if detector_idx < self.total_detectors { + self.syndrome[detector_idx] = value; + } + } + + /// Feed a dense syndrome slice (all detectors, in order). + pub fn feed_dense(&mut self, syndrome: &[u8]) { + let len = syndrome.len().min(self.total_detectors); + self.syndrome[..len].copy_from_slice(&syndrome[..len]); + } + + /// Feed sparse detection events: (`detector_index`, value) pairs. + pub fn feed_sparse(&mut self, detectors: &[(u32, u8)]) { + for &(det, val) in detectors { + self.feed_detection(det as usize, val); + } + self.rounds_fed += 1; + } + + /// Decode the accumulated syndrome using the full-circuit OSD. + /// + /// Returns the observable correction mask. This is the final + /// correction to apply to raw measurement outcomes. + pub fn flush(&mut self) -> Result { + let obs = self.inner.decode_shot(&self.syndrome)?; + self.accumulated_obs = obs; + Ok(obs) + } + + /// Decode a full syndrome at once (convenience for batch mode). + pub fn decode_shot(&mut self, syndrome: &[u8]) -> Result { + self.feed_dense(syndrome); + self.flush() + } + + /// Current accumulated observable correction. + #[must_use] + pub fn accumulated_obs(&self) -> u64 { + self.accumulated_obs + } + + /// Number of segments in the algorithm. + #[must_use] + pub fn num_segments(&self) -> usize { + self.inner.num_segments() + } + + /// Rounds fed so far. + #[must_use] + pub fn rounds_fed(&self) -> usize { + self.rounds_fed + } + + /// Access the boundary gates for frame propagation. + #[must_use] + pub fn boundary_gates(&self) -> &[Vec] { + &self.inner.boundary_gates + } + + /// Apply boundary gate to a Pauli frame (delegates to inner). + pub fn apply_boundary_gate(frame: &mut u64, gate: &BoundaryGate) { + LogicalAlgorithmDecoder::apply_boundary_gate(frame, gate); + } + + /// Reset for the next shot. + pub fn reset(&mut self) { + self.syndrome.fill(0); + self.rounds_fed = 0; + self.accumulated_obs = 0; + } +} + +/// Simulate streaming decode on a batch of samples. +/// +/// For each shot: feeds the dense syndrome, flushes, checks against expected. +/// Returns the number of logical errors. This simulates what a real-time +/// system would do — feed syndromes and flush at the end. +pub fn streaming_decode_count( + decoder: &mut StreamingLogicalDecoder, + syndromes: &[Vec], + expected_masks: &[u64], +) -> Result { + let mut errors = 0; + for (syn, &expected) in syndromes.iter().zip(expected_masks.iter()) { + decoder.reset(); + let predicted = decoder.decode_shot(syn)?; + if predicted != expected { + errors += 1; + } + } + Ok(errors) +} + +// ============================================================================ +// Budget-aware logical circuit decoder +// ============================================================================ + +use crate::decode_budget::{DecodeBudget, DecodeStrategy, DetectorRegion}; + +/// Budget-aware decoder for logical quantum circuits. +/// +/// Composes a `DecodeStrategy` (which handles the decode/commit pattern) +/// with segment tracking and Pauli frame propagation. The strategy is +/// selected based on the hardware's time budget. +/// +/// # Decode Modes +/// +/// - **Offline** (ion trap / simulation): `FullCircuitStrategy` — buffer +/// everything, decode at end. Maximum accuracy. +/// - **Streaming** (neutral atom): `CommittedOsdStrategy` — decode and +/// commit at segment boundaries. Bounded memory. +/// - **Real-time** (superconducting): windowed UF with ghost protocol +/// (future). +/// +/// All modes use the same segment + gate + frame infrastructure. +pub struct LogicalCircuitDecoder { + /// The decode strategy (owns the inner decoder). + strategy: Box, + /// Segment metadata. + segments: Vec, + /// Cumulative detector offsets per segment. + _segment_offsets: Vec, + /// Gates at segment boundaries. + boundary_gates: Vec>, + /// Per-qubit Pauli frames. + frames: Vec, + /// Decode budget. + budget: DecodeBudget, + /// Syndrome buffer. + syndrome: Vec, + /// Total detectors. + total_detectors: usize, + /// Current segment being fed. + current_segment: usize, + /// Detectors fed into the current segment so far. + current_segment_fed: usize, +} + +impl LogicalCircuitDecoder { + /// Build from an algorithm descriptor, decode strategy, and budget. + #[must_use] + pub fn new( + descriptor: AlgorithmDescriptor, + strategy: Box, + budget: DecodeBudget, + num_qubits: usize, + ) -> Self { + let mut segment_offsets = Vec::with_capacity(descriptor.segments.len()); + let mut offset = 0; + for seg in &descriptor.segments { + segment_offsets.push(offset); + offset += seg.num_detectors; + } + let total_detectors = offset; + + Self { + strategy, + segments: descriptor.segments, + _segment_offsets: segment_offsets, + boundary_gates: descriptor.boundary_gates, + frames: vec![0u64; num_qubits], + budget, + syndrome: vec![0u8; total_detectors], + total_detectors, + current_segment: 0, + current_segment_fed: 0, + } + } + + /// Decode a full shot (batch mode). + /// + /// For offline/ion trap budgets: equivalent to full-circuit OSD. + /// For streaming budgets: decodes and commits each segment. + pub fn decode_shot(&mut self, full_syndrome: &[u8]) -> Result { + self.reset(); + let len = full_syndrome.len().min(self.total_detectors); + self.syndrome[..len].copy_from_slice(&full_syndrome[..len]); + + // Single decode of the full syndrome. The strategy handles + // commitment internally if it supports it. + self.strategy.decode(&self.syndrome) + } + + /// Batch decode: count logical errors across a batch of shots. + pub fn decode_count( + &mut self, + syndromes: &[Vec], + expected_masks: &[u64], + ) -> Result { + let mut errors = 0; + for (syn, &expected) in syndromes.iter().zip(expected_masks.iter()) { + let predicted = self.decode_shot(syn)?; + if predicted != expected { + errors += 1; + } + } + Ok(errors) + } + + /// Number of segments. + #[must_use] + pub fn num_segments(&self) -> usize { + self.segments.len() + } + + /// Whether the algorithm has any feed-forward decision points. + /// + /// If false, the budget doesn't matter — all corrections are + /// metadata applied at the end (Clifford-only circuit). + /// If true, the reaction time budget is meaningful. + #[must_use] + pub fn has_decision_points(&self) -> bool { + self.boundary_gates + .iter() + .any(|gates| gates.iter().any(BoundaryGate::is_decision_point)) + } + + /// Number of decision points (T gates, magic state injections). + #[must_use] + pub fn num_decision_points(&self) -> usize { + self.boundary_gates + .iter() + .flat_map(|gates| gates.iter()) + .filter(|g| g.is_decision_point()) + .count() + } + + /// Total detectors. + #[must_use] + pub fn total_detectors(&self) -> usize { + self.total_detectors + } + + /// Current Pauli frames (per qubit). + #[must_use] + pub fn frames(&self) -> &[u64] { + &self.frames + } + + /// The decode budget. + #[must_use] + pub fn budget(&self) -> &DecodeBudget { + &self.budget + } + + /// Reset for next shot. + pub fn reset(&mut self) { + self.strategy.reset(); + self.syndrome.fill(0); + self.frames.fill(0); + self.current_segment = 0; + self.current_segment_fed = 0; + } +} + +impl ObservableDecoder for LogicalCircuitDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + self.decode_shot(syndrome) + } +} + +// ============================================================================ +// Strategy: Full Circuit (offline / ion trap) +// ============================================================================ + +/// Full-circuit decode strategy. +/// +/// Buffers the entire syndrome, decodes at flush. Maximum accuracy. +/// Used for offline analysis, ion trap systems, or any budget that +/// allows full-circuit processing. +pub struct FullCircuitStrategy { + inner: Box, +} + +impl FullCircuitStrategy { + /// Wrap any `ObservableDecoder` (typically OSD). + #[must_use] + pub fn new(decoder: Box) -> Self { + Self { inner: decoder } + } +} + +impl DecodeStrategy for FullCircuitStrategy { + fn decode(&mut self, syndrome: &[u8]) -> Result { + self.inner.decode_to_observables(syndrome) + } + + fn commit(&mut self, _region: &DetectorRegion) -> Result { + // Full circuit doesn't commit incrementally + Ok(0) + } + + fn committed_obs(&self) -> u64 { + 0 + } + + fn reset(&mut self) { + // No state to reset for full-circuit strategy + } +} + +// ============================================================================ +// Strategy: Windowed OSD (neutral atom / medium budget) +// ============================================================================ + +/// Windowed OSD strategy: per-observable subgraph windowed decoding. +/// +/// Each observable's subgraph is graphlike (no hyperedges). A windowed +/// decoder (sandwich or plain PM) runs inside each subgraph with bounded +/// latency. The full matching graph is pre-built; only syndrome routing +/// and per-window matching are per-shot work. +/// +/// This achieves bounded-latency streaming with OSD-level accuracy. +pub struct WindowedOsdStrategy { + /// Per-subgraph decoders (windowed or plain). + subgraph_decoders: Vec>, + /// Per-subgraph detector maps: `subgraph_detector_maps`[i][local] = global. + detector_maps: Vec>, + /// Per-subgraph sub-syndrome buffers (reusable). + sub_syndromes: Vec>, + /// Number of observables. + _num_observables: usize, +} + +impl WindowedOsdStrategy { + /// Build from pre-extracted subgraph DEMs and detector maps. + /// + /// `subgraph_dems`: per-observable DEM strings (graphlike). + /// `detector_maps`: per-observable local→global detector index maps. + /// `factory`: creates the inner decoder for each subgraph DEM. + pub fn new( + subgraph_dems: Vec, + detector_maps: Vec>, + mut factory: F, + ) -> Result + where + F: FnMut(&str) -> Result, DecoderError>, + { + let num_observables = subgraph_dems.len(); + let mut decoders = Vec::with_capacity(num_observables); + let mut sub_syndromes = Vec::with_capacity(num_observables); + + for (i, dem_str) in subgraph_dems.iter().enumerate() { + let dec = factory(dem_str)?; + let n = detector_maps.get(i).map_or(0, std::vec::Vec::len); + sub_syndromes.push(vec![0u8; n]); + decoders.push(dec); + } + + Ok(Self { + subgraph_decoders: decoders, + detector_maps, + sub_syndromes, + _num_observables: num_observables, + }) + } +} + +impl DecodeStrategy for WindowedOsdStrategy { + fn decode(&mut self, syndrome: &[u8]) -> Result { + let mut obs_mask = 0u64; + + for (i, (dec, dmap)) in self + .subgraph_decoders + .iter_mut() + .zip(self.detector_maps.iter()) + .enumerate() + { + let n = dmap.len(); + if n == 0 { + continue; + } + + // Route global syndrome to subgraph-local syndrome + let buf = &mut self.sub_syndromes[i]; + for (local, &global) in dmap.iter().enumerate() { + buf[local] = if global < syndrome.len() { + syndrome[global] + } else { + 0 + }; + } + + // Decode this subgraph + let sub_obs = dec.decode_to_observables(&buf[..n])?; + if sub_obs & 1 != 0 { + obs_mask |= 1 << i; + } + } + + Ok(obs_mask) + } + + fn commit(&mut self, _region: &DetectorRegion) -> Result { + // Commitment is handled internally by the windowed inner decoders + Ok(0) + } + + fn committed_obs(&self) -> u64 { + 0 + } + + fn reset(&mut self) { + for buf in &mut self.sub_syndromes { + buf.fill(0); + } + } +} + +#[cfg(test)] +mod tests { + use super::*; + + struct FixedDecoder(u64); + impl ObservableDecoder for FixedDecoder { + fn decode_to_observables(&mut self, _: &[u8]) -> Result { + Ok(self.0) + } + } + + #[test] + fn test_single_segment() { + let desc = AlgorithmDescriptor { + segments: vec![SegmentDescriptor { + num_detectors: 4, + num_observables: 2, + }], + boundary_gates: vec![], + num_observables: 2, + }; + let mut dec = LogicalAlgorithmDecoder::new(Box::new(FixedDecoder(0b01)), desc); + assert_eq!(dec.decode_shot(&[0, 1, 0, 1]).unwrap(), 0b01); + } + + #[test] + fn test_hadamard_frame() { + let mut frame = 0b01u64; // X correction on bit 0 + LogicalAlgorithmDecoder::apply_boundary_gate( + &mut frame, + &BoundaryGate::Hadamard { + x_obs_bit: 0, + z_obs_bit: 1, + }, + ); + assert_eq!(frame, 0b10); // X became Z + } + + #[test] + fn test_cnot_frame() { + let mut frame = 0b0001u64; // X on control (bit 0) + LogicalAlgorithmDecoder::apply_boundary_gate( + &mut frame, + &BoundaryGate::Cnot { + ctrl_x_bit: 0, + ctrl_z_bit: 1, + tgt_x_bit: 2, + tgt_z_bit: 3, + }, + ); + assert_eq!(frame, 0b0101); // X propagated to target + } + + #[test] + fn test_logical_circuit_decoder_unlimited() { + let desc = AlgorithmDescriptor { + segments: vec![ + SegmentDescriptor { + num_detectors: 4, + num_observables: 2, + }, + SegmentDescriptor { + num_detectors: 4, + num_observables: 2, + }, + ], + boundary_gates: vec![vec![BoundaryGate::Hadamard { + x_obs_bit: 0, + z_obs_bit: 1, + }]], + num_observables: 2, + }; + + let strategy = FullCircuitStrategy::new(Box::new(FixedDecoder(0b01))); + let budget = DecodeBudget::unlimited(); + + let mut dec = LogicalCircuitDecoder::new(desc, Box::new(strategy), budget, 1); + let result = dec.decode_shot(&[0, 0, 0, 0, 0, 0, 0, 0]).unwrap(); + assert_eq!(result, 0b01); + } + + #[test] + fn test_cnot_frame_z_backward() { + // Z on target should propagate back to control + let mut frame = 0b1000u64; // Z on target (bit 3) + LogicalAlgorithmDecoder::apply_boundary_gate( + &mut frame, + &BoundaryGate::Cnot { + ctrl_x_bit: 0, + ctrl_z_bit: 1, + tgt_x_bit: 2, + tgt_z_bit: 3, + }, + ); + assert_eq!(frame, 0b1010); // Z propagated back to control Z (bit 1) + } + + #[test] + fn test_cnot_frame_both_directions() { + // X on control + Z on target -> both propagate + let mut frame = 0b1001u64; // X on ctrl (bit 0), Z on tgt (bit 3) + LogicalAlgorithmDecoder::apply_boundary_gate( + &mut frame, + &BoundaryGate::Cnot { + ctrl_x_bit: 0, + ctrl_z_bit: 1, + tgt_x_bit: 2, + tgt_z_bit: 3, + }, + ); + // X ctrl -> X tgt (bit 2), Z tgt -> Z ctrl (bit 1) + assert_eq!(frame, 0b1111); + } + + #[test] + fn test_sgate_frame_x_induces_z() { + // S gate: X correction induces Z correction (X -> XZ = Y) + let mut frame = 0b01u64; // X correction on bit 0 + LogicalAlgorithmDecoder::apply_boundary_gate( + &mut frame, + &BoundaryGate::SGate { + x_obs_bit: 0, + z_obs_bit: 1, + }, + ); + assert_eq!(frame, 0b11); // X stays, Z also set + } + + #[test] + fn test_sgate_frame_z_unchanged() { + // S gate: Z correction is unchanged (S commutes with Z) + let mut frame = 0b10u64; // Z correction on bit 1 + LogicalAlgorithmDecoder::apply_boundary_gate( + &mut frame, + &BoundaryGate::SGate { + x_obs_bit: 0, + z_obs_bit: 1, + }, + ); + assert_eq!(frame, 0b10); // Z stays, no X induced + } + + #[test] + fn test_sgate_frame_no_correction() { + let mut frame = 0u64; + LogicalAlgorithmDecoder::apply_boundary_gate( + &mut frame, + &BoundaryGate::SGate { + x_obs_bit: 0, + z_obs_bit: 1, + }, + ); + assert_eq!(frame, 0); // No correction, no change + } + + #[test] + fn test_t_injection_frame_ancilla_z_folds() { + // T injection: ancilla Z bit folds into data Z bit + let mut frame = 0b1000u64; // ancilla Z set (bit 3) + LogicalAlgorithmDecoder::apply_boundary_gate( + &mut frame, + &BoundaryGate::TGateInjection { + z_obs_bit: 1, // data Z + ancilla_z_bit: 3, // ancilla Z + }, + ); + assert_eq!(frame, 0b1010); // data Z (bit 1) flipped + } + + #[test] + fn test_t_injection_frame_ancilla_z_cancels() { + // If data Z already set and ancilla Z set, they cancel (XOR) + let mut frame = 0b1010u64; // both data Z (bit 1) and ancilla Z (bit 3) + LogicalAlgorithmDecoder::apply_boundary_gate( + &mut frame, + &BoundaryGate::TGateInjection { + z_obs_bit: 1, + ancilla_z_bit: 3, + }, + ); + assert_eq!(frame, 0b1000); // data Z cancelled, ancilla unchanged + } + + #[test] + fn test_t_injection_frame_no_ancilla_z() { + // No ancilla Z -> no change + let mut frame = 0b0010u64; // data Z set, ancilla Z not set + LogicalAlgorithmDecoder::apply_boundary_gate( + &mut frame, + &BoundaryGate::TGateInjection { + z_obs_bit: 1, + ancilla_z_bit: 3, + }, + ); + assert_eq!(frame, 0b0010); // unchanged + } + + #[test] + fn test_hadamard_frame_swap_both() { + // Both X and Z set -> swap + let mut frame = 0b11u64; + LogicalAlgorithmDecoder::apply_boundary_gate( + &mut frame, + &BoundaryGate::Hadamard { + x_obs_bit: 0, + z_obs_bit: 1, + }, + ); + assert_eq!(frame, 0b11); // Swap of (1,1) is still (1,1) + } + + #[test] + fn test_hadamard_frame_z_to_x() { + let mut frame = 0b10u64; // Z only + LogicalAlgorithmDecoder::apply_boundary_gate( + &mut frame, + &BoundaryGate::Hadamard { + x_obs_bit: 0, + z_obs_bit: 1, + }, + ); + assert_eq!(frame, 0b01); // Z became X + } + + #[test] + fn test_is_decision_point() { + assert!( + BoundaryGate::TGateInjection { + z_obs_bit: 1, + ancilla_z_bit: 3, + } + .is_decision_point() + ); + + assert!( + !BoundaryGate::Hadamard { + x_obs_bit: 0, + z_obs_bit: 1, + } + .is_decision_point() + ); + + assert!( + !BoundaryGate::Cnot { + ctrl_x_bit: 0, + ctrl_z_bit: 1, + tgt_x_bit: 2, + tgt_z_bit: 3, + } + .is_decision_point() + ); + + assert!( + !BoundaryGate::SGate { + x_obs_bit: 0, + z_obs_bit: 1, + } + .is_decision_point() + ); + } + + #[test] + fn test_budget_windowed_vs_unlimited() { + use std::time::Duration; + let windowed = DecodeBudget::from_reaction_time(Duration::from_millis(1), 7); + assert!(windowed.is_windowed()); + + let unlimited = DecodeBudget::unlimited(); + assert!(unlimited.is_unlimited()); + } + + #[test] + fn test_streaming_feed_dense_and_flush() { + let desc = AlgorithmDescriptor { + segments: vec![SegmentDescriptor { + num_detectors: 4, + num_observables: 2, + }], + boundary_gates: vec![], + num_observables: 2, + }; + let inner = LogicalAlgorithmDecoder::new(Box::new(FixedDecoder(0b10)), desc); + let mut streaming = StreamingLogicalDecoder::new(inner); + + // Feed full syndrome at once + let result = streaming.decode_shot(&[0, 1, 0, 1]).unwrap(); + assert_eq!(result, 0b10); + assert_eq!(streaming.accumulated_obs(), 0b10); + } + + #[test] + fn test_streaming_feed_sparse() { + let desc = AlgorithmDescriptor { + segments: vec![SegmentDescriptor { + num_detectors: 4, + num_observables: 2, + }], + boundary_gates: vec![], + num_observables: 2, + }; + let inner = LogicalAlgorithmDecoder::new(Box::new(FixedDecoder(0b01)), desc); + let mut streaming = StreamingLogicalDecoder::new(inner); + + // Feed individual detectors + streaming.feed_detection(1, 1); + streaming.feed_detection(3, 1); + let result = streaming.flush().unwrap(); + assert_eq!(result, 0b01); + } + + #[test] + fn test_streaming_reset() { + let desc = AlgorithmDescriptor { + segments: vec![SegmentDescriptor { + num_detectors: 4, + num_observables: 2, + }], + boundary_gates: vec![], + num_observables: 2, + }; + let inner = LogicalAlgorithmDecoder::new(Box::new(FixedDecoder(0b11)), desc); + let mut streaming = StreamingLogicalDecoder::new(inner); + + streaming.decode_shot(&[1, 0, 1, 0]).unwrap(); + assert_eq!(streaming.accumulated_obs(), 0b11); + + streaming.reset(); + assert_eq!(streaming.accumulated_obs(), 0); + } + + #[test] + fn test_streaming_decode_count() { + let desc = AlgorithmDescriptor { + segments: vec![SegmentDescriptor { + num_detectors: 2, + num_observables: 1, + }], + boundary_gates: vec![], + num_observables: 1, + }; + let inner = LogicalAlgorithmDecoder::new( + Box::new(FixedDecoder(0b1)), + desc, // always predicts obs flip + ); + let mut streaming = StreamingLogicalDecoder::new(inner); + + let syndromes = vec![vec![0u8, 0], vec![1, 0], vec![0, 1]]; + let expected = vec![0b1, 0b0, 0b1]; // matches on shot 0 and 2 + + let errors = streaming_decode_count(&mut streaming, &syndromes, &expected).unwrap(); + assert_eq!(errors, 1); // only shot 1 is wrong (predicted 1, expected 0) + } +} diff --git a/crates/pecos-decoder-core/src/multi_decoder.rs b/crates/pecos-decoder-core/src/multi_decoder.rs new file mode 100644 index 000000000..c88e291b6 --- /dev/null +++ b/crates/pecos-decoder-core/src/multi_decoder.rs @@ -0,0 +1,245 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Multi-logical-qubit decoder manager. +//! +//! Manages decoder instances for K logical qubits, each with its own +//! Pauli frame. Routes syndromes to the right decoder and maintains +//! per-qubit frames. + +use crate::ObservableDecoder; +use crate::errors::DecoderError; + +/// Manages multiple logical qubit decoders with per-qubit Pauli frames. +pub struct MultiDecoderManager { + /// (label, decoder) per logical qubit. + decoders: Vec<(String, Box)>, + /// Per-qubit accumulated Pauli frame. + frames: Vec, + /// Per-qubit cycle count. + cycle_counts: Vec, +} + +impl MultiDecoderManager { + /// Create with no decoders. + #[must_use] + pub fn new() -> Self { + Self { + decoders: Vec::new(), + frames: Vec::new(), + cycle_counts: Vec::new(), + } + } + + /// Add a logical qubit decoder with a label. + pub fn add_qubit(&mut self, label: impl Into, decoder: Box) { + self.decoders.push((label.into(), decoder)); + self.frames.push(0); + self.cycle_counts.push(0); + } + + /// Number of logical qubits managed. + #[must_use] + pub fn num_qubits(&self) -> usize { + self.decoders.len() + } + + /// Decode one QEC cycle for a specific logical qubit. + /// + /// # Errors + /// + /// Returns `DecoderError` if the decoder fails or the qubit index is out of bounds. + pub fn decode_cycle(&mut self, qubit_idx: usize, syndrome: &[u8]) -> Result { + if qubit_idx >= self.decoders.len() { + return Err(DecoderError::InvalidNodeIndex { + index: qubit_idx, + max: self.decoders.len(), + }); + } + let obs = self.decoders[qubit_idx].1.decode_to_observables(syndrome)?; + self.frames[qubit_idx] ^= obs; + self.cycle_counts[qubit_idx] += 1; + Ok(obs) + } + + /// Get the current Pauli frame for a logical qubit. + #[must_use] + pub fn frame(&self, qubit_idx: usize) -> u64 { + self.frames.get(qubit_idx).copied().unwrap_or(0) + } + + /// Consume and reset the frame for a logical qubit. + pub fn consume_frame(&mut self, qubit_idx: usize) -> u64 { + if qubit_idx >= self.frames.len() { + return 0; + } + let f = self.frames[qubit_idx]; + self.frames[qubit_idx] = 0; + self.cycle_counts[qubit_idx] = 0; + f + } + + /// Label of a logical qubit. + #[must_use] + pub fn label(&self, qubit_idx: usize) -> Option<&str> { + self.decoders.get(qubit_idx).map(|(l, _)| l.as_str()) + } + + /// Apply a transversal CNOT between two logical qubits' Pauli frames. + /// + /// `x_obs_mask`: observable bits that are X-type (propagate control→target). + /// `z_obs_mask`: observable bits that are Z-type (propagate target→control). + /// + /// For a standard surface code with observable 0 = logical observable: + /// use `x_obs_mask = 1, z_obs_mask = 1` (single observable, both X and Z + /// corrections matter depending on the basis). + pub fn apply_transversal_cnot( + &mut self, + control_idx: usize, + target_idx: usize, + x_obs_mask: u64, + z_obs_mask: u64, + ) { + if control_idx >= self.frames.len() || target_idx >= self.frames.len() { + return; + } + let ctrl_frame = self.frames[control_idx]; + let tgt_frame = self.frames[target_idx]; + + // X-type: control → target + self.frames[target_idx] ^= ctrl_frame & x_obs_mask; + // Z-type: target → control + self.frames[control_idx] ^= tgt_frame & z_obs_mask; + } + + /// Apply a logical Hadamard to a qubit's Pauli frame. + /// + /// Swaps X-type and Z-type frame bits. + pub fn apply_hadamard(&mut self, qubit_idx: usize, x_obs_mask: u64, z_obs_mask: u64) { + if qubit_idx >= self.frames.len() { + return; + } + let f = self.frames[qubit_idx]; + let x_bits = f & x_obs_mask; + let z_bits = f & z_obs_mask; + self.frames[qubit_idx] &= !(x_obs_mask | z_obs_mask); + self.frames[qubit_idx] |= if x_bits != 0 { z_obs_mask } else { 0 }; + self.frames[qubit_idx] |= if z_bits != 0 { x_obs_mask } else { 0 }; + } + + /// Mutable access to the frame for a qubit (for custom gate propagation). + pub fn frame_mut(&mut self, qubit_idx: usize) -> Option<&mut u64> { + self.frames.get_mut(qubit_idx) + } + + /// Replace the decoder for a qubit (e.g., after lattice surgery changes the DEM). + /// + /// # Errors + /// + /// Returns error if `qubit_idx` is out of bounds. + pub fn replace_decoder( + &mut self, + qubit_idx: usize, + decoder: Box, + ) -> Result<(), crate::errors::DecoderError> { + if qubit_idx >= self.decoders.len() { + return Err(crate::errors::DecoderError::InvalidNodeIndex { + index: qubit_idx, + max: self.decoders.len(), + }); + } + self.decoders[qubit_idx].1 = decoder; + Ok(()) + } +} + +impl Default for MultiDecoderManager { + fn default() -> Self { + Self::new() + } +} + +#[cfg(test)] +mod tests { + use super::*; + + struct FixedDecoder(u64); + impl ObservableDecoder for FixedDecoder { + fn decode_to_observables(&mut self, _: &[u8]) -> Result { + Ok(self.0) + } + } + + #[test] + fn test_multi_qubit() { + let mut mgr = MultiDecoderManager::new(); + mgr.add_qubit("q0", Box::new(FixedDecoder(0b01))); + mgr.add_qubit("q1", Box::new(FixedDecoder(0b10))); + + assert_eq!(mgr.num_qubits(), 2); + assert_eq!(mgr.label(0), Some("q0")); + + mgr.decode_cycle(0, &[]).unwrap(); + mgr.decode_cycle(1, &[]).unwrap(); + + assert_eq!(mgr.frame(0), 0b01); + assert_eq!(mgr.frame(1), 0b10); + } + + #[test] + fn test_consume_frame() { + let mut mgr = MultiDecoderManager::new(); + mgr.add_qubit("q0", Box::new(FixedDecoder(1))); + mgr.decode_cycle(0, &[]).unwrap(); + assert_eq!(mgr.consume_frame(0), 1); + assert_eq!(mgr.frame(0), 0); + } + + #[test] + fn test_transversal_cnot() { + let mut mgr = MultiDecoderManager::new(); + mgr.add_qubit("ctrl", Box::new(FixedDecoder(0))); + mgr.add_qubit("tgt", Box::new(FixedDecoder(0))); + + // Set X correction on control (bit 0). + *mgr.frame_mut(0).unwrap() = 0b01; + + // Transversal CNOT: X propagates ctrl→tgt. + mgr.apply_transversal_cnot(0, 1, 0b01, 0b10); + assert_eq!(mgr.frame(0), 0b01); + assert_eq!(mgr.frame(1), 0b01); // X propagated + } + + #[test] + fn test_hadamard() { + let mut mgr = MultiDecoderManager::new(); + mgr.add_qubit("q0", Box::new(FixedDecoder(0))); + *mgr.frame_mut(0).unwrap() = 0b01; // X correction + + mgr.apply_hadamard(0, 0b01, 0b10); + assert_eq!(mgr.frame(0), 0b10); // became Z correction + } + + #[test] + fn test_replace_decoder() { + let mut mgr = MultiDecoderManager::new(); + mgr.add_qubit("q0", Box::new(FixedDecoder(0b01))); + mgr.decode_cycle(0, &[]).unwrap(); + assert_eq!(mgr.frame(0), 0b01); + + // Replace decoder (e.g., after lattice surgery changes the DEM). + mgr.replace_decoder(0, Box::new(FixedDecoder(0b10))) + .unwrap(); + mgr.decode_cycle(0, &[]).unwrap(); + assert_eq!(mgr.frame(0), 0b11); // 01 ^ 10 = 11 + } +} diff --git a/crates/pecos-decoder-core/src/observable_subgraph.rs b/crates/pecos-decoder-core/src/observable_subgraph.rs new file mode 100644 index 000000000..76dfec131 --- /dev/null +++ b/crates/pecos-decoder-core/src/observable_subgraph.rs @@ -0,0 +1,947 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Per-observable subgraph decoder for transversal gates. +//! +//! Based on the insight (proved independently by Serra-Peralta et al. +//! arXiv:2505.13599 and Cain et al. arXiv:2505.13587) that per-observable +//! subgraphs of a transversal-gate DEM are always graphlike — even when +//! the full DEM contains weight-3+ hyperedges. +//! +//! # Algorithm +//! +//! 1. Classify each detector by (`logical_qubit`, `stabilizer_type`) using +//! spatial coordinates +//! 2. For each observable, find its boundary edges (1-detector mechanisms) +//! to identify which (qubit, `stab_type`) groups form its observing region +//! 3. Extract a sub-DEM restricted to those detectors +//! 4. Run any MWPM-compatible decoder on each subgraph independently +//! 5. Combine per-observable corrections +//! +//! # Observing Region +//! +//! The observing region for observable k is NOT a transitive closure over +//! shared detectors. It is determined by the *physical structure*: +//! - Find boundary edges (1-detector + observable) for observable k +//! - Each boundary edge's detector belongs to a (qubit, `stab_type`) group +//! - ALL detectors in those groups form the observing region +//! - This preserves the graphlike property of each subgraph + +use std::collections::{BTreeMap, BTreeSet}; + +use crate::ObservableDecoder; +use crate::dem::{DemMatchingGraph, MatchingEdge}; +use crate::errors::DecoderError; + +/// Sparse representation of a parsed DEM, avoiding the dense matrix +/// allocation of [`DemCheckMatrix`]. Also collects detector coordinates +/// in a single pass to avoid re-scanning the DEM string. +struct SparseDem { + /// Per-mechanism: (probability, `detector_ids`, `observable_ids`). + mechanisms: Vec<(f64, Vec, Vec)>, + /// Detector id → coordinates (spatial + time). + detector_coords: BTreeMap>, + num_detectors: usize, + num_observables: usize, +} + +/// Parse ASCII digits into u32. Faster than `str::parse` for the common case. +#[inline] +fn parse_u32_fast(s: &[u8]) -> Option { + if s.is_empty() { + return None; + } + let mut n: u32 = 0; + for &b in s { + if !b.is_ascii_digit() { + return None; + } + n = n.wrapping_mul(10).wrapping_add(u32::from(b - b'0')); + } + Some(n) +} + +impl SparseDem { + fn from_dem_str(dem: &str) -> Result { + // Estimate capacity: ~1 mechanism per 55 bytes of DEM string. + let est_mechs = dem.len() / 55; + let mut mechanisms = Vec::with_capacity(est_mechs); + let mut detector_coords = BTreeMap::new(); + let mut max_detector: u32 = 0; + let mut max_observable: u32 = 0; + let mut has_any_detector = false; + + let bytes = dem.as_bytes(); + let mut pos = 0; + let len = bytes.len(); + + while pos < len { + // Skip to start of line content (skip whitespace/newlines) + while pos < len + && (bytes[pos] == b' ' + || bytes[pos] == b'\n' + || bytes[pos] == b'\r' + || bytes[pos] == b'\t') + { + pos += 1; + } + if pos >= len { + break; + } + + if bytes[pos] == b'e' && pos + 6 < len && &bytes[pos..pos + 6] == b"error(" { + // Parse error line at byte level. + pos += 6; + // Find closing paren — probability string + let prob_start = pos; + while pos < len && bytes[pos] != b')' { + pos += 1; + } + if pos >= len { + return Err(DecoderError::InvalidConfiguration( + "Missing ) in error line".into(), + )); + } + let prob: f64 = std::str::from_utf8(&bytes[prob_start..pos]) + .unwrap_or("0") + .parse() + .map_err(|_| DecoderError::InvalidConfiguration("Bad probability".into()))?; + pos += 1; // skip ')' + + // Scan for ^ to decide fast vs slow path + let line_start = pos; + while pos < len && bytes[pos] != b'\n' { + pos += 1; + } + let line_end = pos; + let line_bytes = &bytes[line_start..line_end]; + + if line_bytes.contains(&b'^') { + // Slow path: XOR decomposition + let line_str = std::str::from_utf8(line_bytes).unwrap_or(""); + let mut det_set = BTreeSet::new(); + let mut obs_set = BTreeSet::new(); + for component in line_str.split('^') { + for token in component.split_whitespace() { + if let Some(d_str) = token.strip_prefix('D') { + if let Some(d) = parse_u32_fast(d_str.as_bytes()) { + if !det_set.remove(&d) { + det_set.insert(d); + } + if d > max_detector { + max_detector = d; + has_any_detector = true; + } + } + } else if let Some(l_str) = token.strip_prefix('L') + && let Some(l) = parse_u32_fast(l_str.as_bytes()) { + if !obs_set.remove(&l) { + obs_set.insert(l); + } + if l > max_observable { + max_observable = l; + } + } + } + } + mechanisms.push(( + prob, + det_set.into_iter().collect(), + obs_set.into_iter().collect(), + )); + } else { + // Fast path: no XOR. Parse tokens directly into Vecs. + let mut dets = Vec::with_capacity(3); + let mut obs = Vec::with_capacity(1); + let mut i = 0; + while i < line_bytes.len() { + // Skip whitespace + while i < line_bytes.len() && line_bytes[i] == b' ' { + i += 1; + } + if i >= line_bytes.len() { + break; + } + + if line_bytes[i] == b'D' { + i += 1; + let start = i; + while i < line_bytes.len() + && line_bytes[i] >= b'0' + && line_bytes[i] <= b'9' + { + i += 1; + } + if let Some(d) = parse_u32_fast(&line_bytes[start..i]) { + dets.push(d); + if d > max_detector { + max_detector = d; + has_any_detector = true; + } + } + } else if line_bytes[i] == b'L' { + i += 1; + let start = i; + while i < line_bytes.len() + && line_bytes[i] >= b'0' + && line_bytes[i] <= b'9' + { + i += 1; + } + if let Some(l) = parse_u32_fast(&line_bytes[start..i]) { + obs.push(l); + if l > max_observable { + max_observable = l; + } + } + } else { + // Skip unknown token + while i < line_bytes.len() && line_bytes[i] != b' ' { + i += 1; + } + } + } + mechanisms.push((prob, dets, obs)); + } + } else if bytes[pos] == b'd' && pos + 9 < len && &bytes[pos..pos + 9] == b"detector(" { + // Parse detector coordinate declaration. + pos += 9; + let coord_start = pos; + while pos < len && bytes[pos] != b')' { + pos += 1; + } + if pos < len { + let coord_str = std::str::from_utf8(&bytes[coord_start..pos]).unwrap_or(""); + let coords: Vec = coord_str + .split(',') + .filter_map(|s| s.trim().parse().ok()) + .collect(); + pos += 1; // skip ')' + // Find detector ID: "D123" + while pos < len && bytes[pos] == b' ' { + pos += 1; + } + if pos < len && bytes[pos] == b'D' { + pos += 1; + let start = pos; + while pos < len && bytes[pos] >= b'0' && bytes[pos] <= b'9' { + pos += 1; + } + if let Some(d) = parse_u32_fast(&bytes[start..pos]) { + detector_coords.insert(d as usize, coords); + if d > max_detector { + max_detector = d; + has_any_detector = true; + } + } + } + } + // Skip rest of line + while pos < len && bytes[pos] != b'\n' { + pos += 1; + } + } else { + // Skip unknown line + while pos < len && bytes[pos] != b'\n' { + pos += 1; + } + } + } + + let has_any_obs = max_observable > 0 || mechanisms.iter().any(|(_, _, o)| !o.is_empty()); + Ok(Self { + mechanisms, + detector_coords, + num_detectors: if has_any_detector { + max_detector as usize + 1 + } else { + 0 + }, + num_observables: if has_any_obs { + max_observable as usize + 1 + } else { + 0 + }, + }) + } +} + +// ============================================================================ +// Stabilizer coordinate mapping +// ============================================================================ + +/// Identifies a group of detectors by logical qubit and stabilizer type. +#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] +pub struct DetectorGroup { + pub qubit_idx: usize, + pub stab_type: StabType, +} + +/// Stabilizer type (X or Z). +#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] +pub enum StabType { + X, + Z, +} + +/// Stabilizer coordinate map for one logical qubit. +/// +/// Maps stabilizer spatial positions to their type (X or Z). +/// Used to classify detectors by their coordinates. +#[derive(Debug, Clone)] +pub struct QubitStabCoords { + /// X-stabilizer ancilla positions. + pub x_positions: Vec<(f64, f64)>, + /// Z-stabilizer ancilla positions. + pub z_positions: Vec<(f64, f64)>, +} + +/// Stabilizer coordinates for all logical qubits. +/// +/// Entry `i` describes the stabilizers of logical qubit `i`. +pub type StabCoords = Vec; + +/// Classify a detector's spatial coordinates into a `DetectorGroup`. +/// +/// Finds the nearest stabilizer position across all qubits and returns +/// the matching (`qubit_idx`, `stab_type`). Uses exact floating-point +/// comparison with a small tolerance for rounding. +#[must_use] +pub fn classify_detector(x: f64, y: f64, stab_coords: &StabCoords) -> Option { + let eps = 0.01; + for (qubit_idx, qsc) in stab_coords.iter().enumerate() { + for &(sx, sy) in &qsc.x_positions { + if (x - sx).abs() < eps && (y - sy).abs() < eps { + return Some(DetectorGroup { + qubit_idx, + stab_type: StabType::X, + }); + } + } + for &(sx, sy) in &qsc.z_positions { + if (x - sx).abs() < eps && (y - sy).abs() < eps { + return Some(DetectorGroup { + qubit_idx, + stab_type: StabType::Z, + }); + } + } + } + None +} + +// ============================================================================ +// Subgraph partitioning +// ============================================================================ + +/// A sub-DEM for one observable's observing region. +#[derive(Debug, Clone)] +pub struct ObservableSubgraph { + /// Which observable this subgraph decodes. + pub observable_idx: usize, + /// Maps subgraph detector index → full DEM detector index. + pub detector_map: Vec, + /// Maps full DEM detector index → subgraph detector index (None if outside). + pub inverse_map: Vec>, + /// The matching graph for this subgraph. + pub graph: DemMatchingGraph, +} + +/// Partition a DEM into per-observable subgraphs using stabilizer coordinates. +/// +/// This is the correct algorithm: uses the physical structure (which detectors +/// belong to which stabilizer type on which qubit) to determine observing +/// regions, rather than a topological transitive closure. +/// +/// # Arguments +/// +/// * `dem_str` — DEM string in Stim format. Must include `detector(...) D_i` +/// declarations with spatial coordinates. +/// * `stab_coords` — Per-qubit stabilizer coordinate map. Entry `i` gives +/// the X and Z ancilla positions for logical qubit `i`. +/// +/// # Errors +/// +/// Returns error if the DEM is malformed or detector coordinates don't +/// match any stabilizer position. + +/// Extra time padding around each boundary edge. +/// `None` = exact boundary edge times only (default, matches lomatching). +/// `Some(r)` = include detectors at times `t ± r` around each boundary +/// edge time `t`, for additional matching context. +pub type MaxTimeRadius = Option; + +pub fn partition_dem_by_observable( + dem_str: &str, + stab_coords: &StabCoords, +) -> Result, DecoderError> { + partition_dem_by_observable_windowed(dem_str, stab_coords, None) +} + +pub fn partition_dem_by_observable_windowed( + dem_str: &str, + stab_coords: &StabCoords, + max_time_radius: MaxTimeRadius, +) -> Result, DecoderError> { + // Single-pass sparse DEM parsing: mechanisms + detector coordinates. + let sdem = SparseDem::from_dem_str(dem_str)?; + let coord_map = &sdem.detector_coords; + + // Classify each detector into a (qubit, stab_type) group. + let mut det_group: Vec> = vec![None; sdem.num_detectors]; + let mut group_detectors: BTreeMap> = BTreeMap::new(); + + for d in 0..sdem.num_detectors { + if let Some(coords) = coord_map.get(&d) + && coords.len() >= 2 { + let (x, y) = (coords[0], coords[1]); + if let Some(group) = classify_detector(x, y, stab_coords) { + det_group[d] = Some(group); + group_detectors.entry(group).or_default().insert(d); + } + } + } + + // For each observable, find its observing region. + let mut subgraphs = Vec::with_capacity(sdem.num_observables); + + for obs_idx in 0..sdem.num_observables { + // Step 1: Find boundary edges — 1-detector mechanisms that flip + // this observable. Collect (group, time) from each boundary detector. + let mut group_times: BTreeMap> = BTreeMap::new(); + + for (_, dets, obs) in &sdem.mechanisms { + if !obs.contains(&(obs_idx as u32)) { + continue; + } + if dets.len() == 1 { + let d = dets[0] as usize; + if let Some(group) = det_group[d] { + let time = coord_map + .get(&d) + .and_then(|c| c.last().copied()) + .map_or(0, |t| t as i64); + group_times.entry(group).or_default().insert(time); + } + } + } + + // Step 2: For each (group, time) boundary edge, include ALL + // detectors of that group at that time. This matches lomatching's + // per-time-step approach: detectors are included only at times + // where boundary edges exist, not across the full time range. + // With max_time_radius, extend each boundary time by ±radius. + let mut region_detectors = BTreeSet::new(); + for (group, times) in &group_times { + if let Some(dets) = group_detectors.get(group) { + for &d in dets { + let det_time = coord_map + .get(&d) + .and_then(|c| c.last().copied()) + .map_or(0, |t| t as i64); + let in_region = if let Some(radius) = max_time_radius { + times.iter().any(|&t| (det_time - t).abs() <= radius) + } else { + times.contains(&det_time) + }; + if in_region { + region_detectors.insert(d); + } + } + } + } + + if region_detectors.is_empty() { + subgraphs.push(ObservableSubgraph { + observable_idx: obs_idx, + detector_map: Vec::new(), + inverse_map: vec![None; sdem.num_detectors], + graph: DemMatchingGraph { + edges: Vec::new(), + num_detectors: 0, + num_observables: 1, + skipped_hyperedges: 0, + detector_coords: Vec::new(), + }, + }); + continue; + } + + // Step 3: Build detector mapping. + let detector_map: Vec = region_detectors.into_iter().collect(); + let mut inverse_map = vec![None; sdem.num_detectors]; + for (sub_idx, &full_idx) in detector_map.iter().enumerate() { + inverse_map[full_idx] = Some(sub_idx); + } + + // Step 4: Extract edges for this subgraph. + let mut edges = Vec::new(); + let mut skipped = 0; + + for (m, (p, dets, obs)) in sdem.mechanisms.iter().enumerate() { + if *p <= 0.0 { + continue; + } + + // Map mechanism detectors to subgraph indices. + let sub_dets: Vec = dets + .iter() + .filter_map(|&d| inverse_map[d as usize].map(|s| s as u32)) + .collect(); + + if sub_dets.is_empty() { + continue; + } + + let weight = if *p < 1.0 { ((1.0 - p) / p).ln() } else { 0.0 }; + let flips_obs = obs.contains(&(obs_idx as u32)); + let observables = if flips_obs { vec![0u32] } else { vec![] }; + + match sub_dets.len() { + 1 => edges.push(MatchingEdge { + node1: sub_dets[0], + node2: None, + weight, + observables, + probability: *p, + fault_id: m, + }), + 2 => edges.push(MatchingEdge { + node1: sub_dets[0], + node2: Some(sub_dets[1]), + weight, + observables, + probability: *p, + fault_id: m, + }), + _ => skipped += 1, + } + } + + let num_sub = detector_map.len(); + let edges = DemMatchingGraph::merge_parallel_edges(edges); + + subgraphs.push(ObservableSubgraph { + observable_idx: obs_idx, + detector_map, + inverse_map, + graph: DemMatchingGraph { + edges, + num_detectors: num_sub, + num_observables: 1, + skipped_hyperedges: skipped, + detector_coords: Vec::new(), + }, + }); + } + + Ok(subgraphs) +} + +// ============================================================================ +// Decoder +// ============================================================================ + +/// Per-observable subgraph decoder. +/// +/// Wraps a factory function that creates per-subgraph inner decoders. +/// Any `ObservableDecoder` works as the inner decoder (UF, Fusion Blossom, +/// perturbed ensemble, etc.). +pub struct ObservableSubgraphDecoder { + subgraphs: Vec, + decoders: Vec>, + num_observables: usize, + sub_syndromes: Vec>, +} + +impl ObservableSubgraphDecoder { + /// Build from a DEM string, stabilizer coordinates, and inner decoder factory. + /// + /// # Errors + /// + /// Returns error if the DEM is malformed or the factory fails. + pub fn from_dem( + dem: &str, + stab_coords: &StabCoords, + factory: F, + ) -> Result + where + F: FnMut( + &DemMatchingGraph, + ) -> Result, DecoderError>, + { + Self::from_dem_windowed(dem, stab_coords, None, factory) + } + + pub fn from_dem_windowed( + dem: &str, + stab_coords: &StabCoords, + max_time_radius: MaxTimeRadius, + mut factory: F, + ) -> Result + where + F: FnMut( + &DemMatchingGraph, + ) -> Result, DecoderError>, + { + let subgraphs = partition_dem_by_observable_windowed(dem, stab_coords, max_time_radius)?; + let num_observables = subgraphs.len(); + + let mut decoders = Vec::with_capacity(subgraphs.len()); + let mut sub_syndromes = Vec::with_capacity(subgraphs.len()); + for sg in &subgraphs { + decoders.push(factory(&sg.graph)?); + sub_syndromes.push(vec![0u8; sg.detector_map.len()]); + } + + Ok(Self { + subgraphs, + decoders, + num_observables, + sub_syndromes, + }) + } + + /// Number of observables. + #[must_use] + pub fn num_observables(&self) -> usize { + self.num_observables + } + + /// Access a subgraph. + #[must_use] + pub fn subgraph(&self, obs_idx: usize) -> Option<&ObservableSubgraph> { + self.subgraphs.get(obs_idx) + } + + /// Batch decode multiple syndromes, returning error count. + /// + /// For each subgraph, extracts all sub-syndromes into a flat buffer + /// and calls `decode_batch_to_observables` once — avoiding per-shot + /// reset overhead in decoders like `PyMatching`. + pub fn decode_count_batched( + &mut self, + syndromes: &[Vec], + expected_masks: &[u64], + ) -> Result { + let num_shots = syndromes.len(); + if num_shots == 0 { + return Ok(0); + } + + // Per-shot observable predictions, accumulated across subgraphs. + let mut shot_obs: Vec = vec![0u64; num_shots]; + + for (i, (sg, dec)) in self + .subgraphs + .iter() + .zip(self.decoders.iter_mut()) + .enumerate() + { + let n = sg.detector_map.len(); + if n == 0 { + continue; + } + + // Build flat sub-syndrome buffer: num_shots × n bytes. + let mut flat = vec![0u8; num_shots * n]; + for (shot_idx, syn) in syndromes.iter().enumerate() { + let row = &mut flat[shot_idx * n..(shot_idx + 1) * n]; + for (sub_idx, &full_idx) in sg.detector_map.iter().enumerate() { + row[sub_idx] = if full_idx < syn.len() { + syn[full_idx] + } else { + 0 + }; + } + } + + // Batch decode this subgraph. + let sub_masks = dec.decode_batch_to_observables(&flat, num_shots, n)?; + + for (shot_idx, &sub_obs) in sub_masks.iter().enumerate() { + if sub_obs & 1 != 0 { + shot_obs[shot_idx] |= 1 << i; + } + } + } + + // Count errors. + let errors = shot_obs + .iter() + .zip(expected_masks.iter()) + .filter(|(predicted, expected)| predicted != expected) + .count(); + + Ok(errors) + } +} + +impl ObservableDecoder for ObservableSubgraphDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + let mut obs_mask = 0u64; + + for (i, (sg, dec)) in self + .subgraphs + .iter() + .zip(self.decoders.iter_mut()) + .enumerate() + { + let n = sg.detector_map.len(); + if n == 0 { + continue; + } + + let buf = &mut self.sub_syndromes[i]; + for (sub_idx, &full_idx) in sg.detector_map.iter().enumerate() { + buf[sub_idx] = if full_idx < syndrome.len() { + syndrome[full_idx] + } else { + 0 + }; + } + + let sub_obs = dec.decode_to_observables(&buf[..n])?; + + if sub_obs & 1 != 0 { + obs_mask |= 1 << i; + } + } + + Ok(obs_mask) + } +} + +/// Parallel per-observable subgraph decoder using rayon. +pub struct ParallelObservableSubgraphDecoder { + subgraphs: Vec, + decoders: Vec>>, +} + +impl ParallelObservableSubgraphDecoder { + /// Build from a DEM string, stabilizer coordinates, and inner decoder factory. + /// + /// # Errors + /// + /// Returns error if the DEM is malformed or the factory fails. + pub fn from_dem( + dem: &str, + stab_coords: &StabCoords, + mut factory: F, + ) -> Result + where + F: FnMut(&DemMatchingGraph) -> Result, DecoderError>, + { + let subgraphs = partition_dem_by_observable(dem, stab_coords)?; + + let mut decoders = Vec::with_capacity(subgraphs.len()); + for sg in &subgraphs { + decoders.push(std::sync::Mutex::new(factory(&sg.graph)?)); + } + + Ok(Self { + subgraphs, + decoders, + }) + } + + /// Decode using parallel subgraph decoding. + /// + /// # Errors + /// + /// Returns error if any subgraph decoder fails. + pub fn decode_parallel(&self, syndrome: &[u8]) -> Result { + use rayon::prelude::*; + + let results: Vec> = self + .subgraphs + .par_iter() + .zip(self.decoders.par_iter()) + .map(|(sg, dec_mutex)| { + let n = sg.detector_map.len(); + if n == 0 { + return Ok(false); + } + + let mut sub_syn = vec![0u8; n]; + for (sub_idx, &full_idx) in sg.detector_map.iter().enumerate() { + sub_syn[sub_idx] = if full_idx < syndrome.len() { + syndrome[full_idx] + } else { + 0 + }; + } + + let mut dec = dec_mutex.lock().unwrap(); + let sub_obs = dec.decode_to_observables(&sub_syn)?; + Ok(sub_obs & 1 != 0) + }) + .collect(); + + let mut obs_mask = 0u64; + for (i, result) in results.into_iter().enumerate() { + if result? { + obs_mask |= 1 << i; + } + } + Ok(obs_mask) + } +} + +// ============================================================================ +// Tests +// ============================================================================ + +#[cfg(test)] +mod tests { + use super::*; + + struct NullDecoder; + impl ObservableDecoder for NullDecoder { + fn decode_to_observables(&mut self, _: &[u8]) -> Result { + Ok(0) + } + } + + struct FixedDecoder(u64); + impl ObservableDecoder for FixedDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + if syndrome.iter().any(|&v| v != 0) { + Ok(self.0) + } else { + Ok(0) + } + } + } + + fn simple_stab_coords() -> StabCoords { + // Two qubits with non-overlapping X/Z positions. + vec![ + QubitStabCoords { + x_positions: vec![(1.0, 0.0)], + z_positions: vec![(0.0, 1.0)], + }, + QubitStabCoords { + x_positions: vec![(3.0, 0.0)], + z_positions: vec![(2.0, 1.0)], + }, + ] + } + + #[test] + fn test_classify_detector() { + let sc = simple_stab_coords(); + assert_eq!( + classify_detector(1.0, 0.0, &sc), + Some(DetectorGroup { + qubit_idx: 0, + stab_type: StabType::X + }), + ); + assert_eq!( + classify_detector(0.0, 1.0, &sc), + Some(DetectorGroup { + qubit_idx: 0, + stab_type: StabType::Z + }), + ); + assert_eq!( + classify_detector(3.0, 0.0, &sc), + Some(DetectorGroup { + qubit_idx: 1, + stab_type: StabType::X + }), + ); + assert_eq!(classify_detector(99.0, 99.0, &sc), None); + } + + #[test] + fn test_partition_simple() { + // Two detectors with coords, one observable. + let dem = concat!( + "detector(1, 0, 0) D0\n", + "detector(0, 1, 0) D1\n", + "error(0.01) D0 D1 L0\n", + "error(0.01) D0 L0\n", // boundary edge → D0 is (qubit 0, X) + ); + let sc = simple_stab_coords(); + let sgs = partition_dem_by_observable(dem, &sc).unwrap(); + assert_eq!(sgs.len(), 1); + // Boundary edge D0 L0 → D0 is qubit 0 X-type. + // Observing region = all qubit-0 X-type detectors = {D0}. + // But D0-D1 is also an observable mechanism, and D1 is qubit 0 Z-type. + // Since D1 is NOT in the same group as D0, it's excluded from the + // observing region. The edge D0-D1 projects to D0-boundary within + // the subgraph. + assert_eq!(sgs[0].detector_map, vec![0]); + } + + #[test] + fn test_partition_two_qubits() { + let dem = concat!( + "detector(1, 0, 0) D0\n", + "detector(0, 1, 0) D1\n", + "detector(3, 0, 0) D2\n", + "detector(2, 1, 0) D3\n", + "error(0.01) D0 L0\n", // boundary: D0 = qubit 0 X + "error(0.01) D0 D1\n", // D0-D1 edge + "error(0.01) D2 L1\n", // boundary: D2 = qubit 1 X + "error(0.01) D2 D3\n", // D2-D3 edge + ); + let sc = simple_stab_coords(); + let sgs = partition_dem_by_observable(dem, &sc).unwrap(); + assert_eq!(sgs.len(), 2); + assert_eq!(sgs[0].detector_map, vec![0]); // qubit 0 X-type only + assert_eq!(sgs[1].detector_map, vec![2]); // qubit 1 X-type only + } + + #[test] + fn test_decoder_routing() { + let dem = concat!( + "detector(1, 0, 0) D0\n", + "detector(3, 0, 0) D1\n", + "error(0.01) D0 L0\n", + "error(0.01) D1 L1\n", + ); + let sc = simple_stab_coords(); + let mut dec = ObservableSubgraphDecoder::from_dem(dem, &sc, |_| { + Ok(Box::new(FixedDecoder(1)) as Box) + }) + .unwrap(); + + // Defect in obs 0's region only + let obs = dec.decode_to_observables(&[1, 0]).unwrap(); + assert_eq!(obs, 0b01); + + // Defect in obs 1's region only + let obs = dec.decode_to_observables(&[0, 1]).unwrap(); + assert_eq!(obs, 0b10); + } + + #[test] + fn test_parallel_decoder() { + let dem = concat!( + "detector(1, 0, 0) D0\n", + "detector(3, 0, 0) D1\n", + "error(0.01) D0 L0\n", + "error(0.01) D1 L1\n", + ); + let sc = simple_stab_coords(); + let dec = ParallelObservableSubgraphDecoder::from_dem(dem, &sc, |_| { + Ok(Box::new(NullDecoder) as Box) + }) + .unwrap(); + + let obs = dec.decode_parallel(&[0, 0]).unwrap(); + assert_eq!(obs, 0); + } +} diff --git a/crates/pecos-decoder-core/src/pauli_frame.rs b/crates/pecos-decoder-core/src/pauli_frame.rs new file mode 100644 index 000000000..a2172b632 --- /dev/null +++ b/crates/pecos-decoder-core/src/pauli_frame.rs @@ -0,0 +1,245 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Pauli frame accumulator for real-time QEC. +//! +//! In a real QEC system, the decoder runs once per QEC cycle, producing +//! an observable mask. These masks accumulate into a Pauli frame that +//! tracks the net logical correction. The frame is consumed only when +//! a logical operation requires it (T-gate injection, logical measurement). +//! +//! # Example +//! +//! ```ignore +//! let mut frame = PauliFrameAccumulator::new(decoder); +//! +//! // QEC cycles +//! for syndrome in syndrome_stream { +//! frame.decode_cycle(&syndrome)?; +//! } +//! +//! // At logical measurement: consume frame +//! let correction = frame.consume_frame(); +//! let logical_result = raw_measurement ^ (correction & 1); +//! ``` + +use crate::ObservableDecoder; +use crate::errors::DecoderError; + +/// Accumulates Pauli frame corrections across QEC cycles. +/// +/// Wraps any `ObservableDecoder` and XORs each cycle's observable mask +/// into a running frame. The frame represents the net logical correction +/// needed at the current point in the computation. +pub struct PauliFrameAccumulator { + decoder: Box, + frame: u64, + cycle_count: usize, +} + +impl PauliFrameAccumulator { + /// Create from any observable decoder. + #[must_use] + pub fn new(decoder: Box) -> Self { + Self { + decoder, + frame: 0, + cycle_count: 0, + } + } + + /// Decode one QEC cycle's syndrome and accumulate into the frame. + /// + /// # Errors + /// + /// Returns `DecoderError` if the inner decoder fails. + pub fn decode_cycle(&mut self, syndrome: &[u8]) -> Result { + let obs = self.decoder.decode_to_observables(syndrome)?; + self.frame ^= obs; + self.cycle_count += 1; + Ok(obs) + } + + /// Current accumulated Pauli frame (does not reset). + #[must_use] + pub fn current_frame(&self) -> u64 { + self.frame + } + + /// Consume the frame: returns the accumulated mask and resets to zero. + /// + /// Call this at logical operations (T-gate, measurement) to get the + /// correction and start fresh for the next logical cycle. + pub fn consume_frame(&mut self) -> u64 { + let f = self.frame; + self.frame = 0; + self.cycle_count = 0; + f + } + + /// Number of QEC cycles since last reset/consume. + #[must_use] + pub fn cycle_count(&self) -> usize { + self.cycle_count + } + + /// Manually flip a frame bit (e.g., for deterministic corrections). + pub fn flip_bit(&mut self, bit: u32) { + self.frame ^= 1u64 << bit; + } + + /// Direct access to the frame bits. + #[must_use] + pub fn frame_mut(&mut self) -> &mut u64 { + &mut self.frame + } + + /// Access the inner decoder. + pub fn decoder_mut(&mut self) -> &mut dyn ObservableDecoder { + &mut *self.decoder + } +} + +/// Propagate Pauli frames through a transversal CNOT. +/// +/// When a logical CNOT is applied from control to target: +/// - X errors propagate: control → target (`X_c` → `X_c` ⊗ `X_t`) +/// - Z errors propagate: target → control (`Z_t` → `Z_c` ⊗ `Z_t`) +/// +/// For observable masks (bit k = observable k): +/// - X-type observables on control propagate to target +/// - Z-type observables on target propagate to control +/// +/// `x_obs_mask`: which observable bits are X-type (propagate forward) +/// `z_obs_mask`: which observable bits are Z-type (propagate backward) +pub fn propagate_cnot_frames( + control: &mut PauliFrameAccumulator, + target: &mut PauliFrameAccumulator, + x_obs_mask: u64, + z_obs_mask: u64, +) { + let ctrl_frame = control.current_frame(); + let tgt_frame = target.current_frame(); + + // X-type bits on control propagate to target: target ^= control & x_mask + *target.frame_mut() ^= ctrl_frame & x_obs_mask; + + // Z-type bits on target propagate to control: control ^= target & z_mask + *control.frame_mut() ^= tgt_frame & z_obs_mask; +} + +/// Propagate Pauli frame through a logical S gate (phase gate). +/// +/// S gate: X → Y = iXZ, Z → Z. For the frame: +/// - Z-type bits are unchanged +/// - X-type bits that are set also flip the corresponding Z-type bit +pub fn propagate_s_gate_frame(frame: &mut PauliFrameAccumulator, x_obs_mask: u64, z_obs_mask: u64) { + let f = frame.current_frame(); + // X-type corrections also induce Z-type corrections after S gate + *frame.frame_mut() ^= (f & x_obs_mask) & z_obs_mask; +} + +/// Propagate Pauli frame through a logical Hadamard. +/// +/// H gate: X ↔ Z. Swaps X-type and Z-type frame bits. +pub fn propagate_h_gate_frame(frame: &mut PauliFrameAccumulator, x_obs_mask: u64, z_obs_mask: u64) { + let f = frame.current_frame(); + let x_bits = f & x_obs_mask; + let z_bits = f & z_obs_mask; + // Clear both, then swap + *frame.frame_mut() &= !(x_obs_mask | z_obs_mask); + // X bits go to Z positions, Z bits go to X positions + // (This assumes x_obs_mask and z_obs_mask don't overlap and have + // matching bit positions. For a single logical qubit with obs 0 = X + // and obs 1 = Z: x_mask=0b01, z_mask=0b10, swap bits 0 and 1.) + *frame.frame_mut() |= if x_bits != 0 { z_obs_mask } else { 0 }; + *frame.frame_mut() |= if z_bits != 0 { x_obs_mask } else { 0 }; +} + +#[cfg(test)] +mod tests { + use super::*; + + struct FixedDecoder(u64); + impl ObservableDecoder for FixedDecoder { + fn decode_to_observables(&mut self, _: &[u8]) -> Result { + Ok(self.0) + } + } + + #[test] + fn test_accumulate_xor() { + let mut frame = PauliFrameAccumulator::new(Box::new(FixedDecoder(0b01))); + frame.decode_cycle(&[]).unwrap(); + assert_eq!(frame.current_frame(), 0b01); + frame.decode_cycle(&[]).unwrap(); + assert_eq!(frame.current_frame(), 0b00); // XOR cancels + frame.decode_cycle(&[]).unwrap(); + assert_eq!(frame.current_frame(), 0b01); + assert_eq!(frame.cycle_count(), 3); + } + + #[test] + fn test_consume_resets() { + let mut frame = PauliFrameAccumulator::new(Box::new(FixedDecoder(0b11))); + frame.decode_cycle(&[]).unwrap(); + assert_eq!(frame.consume_frame(), 0b11); + assert_eq!(frame.current_frame(), 0); + assert_eq!(frame.cycle_count(), 0); + } + + #[test] + fn test_flip_bit() { + let mut frame = PauliFrameAccumulator::new(Box::new(FixedDecoder(0))); + frame.flip_bit(2); + assert_eq!(frame.current_frame(), 0b100); + frame.flip_bit(2); + assert_eq!(frame.current_frame(), 0); + } + + #[test] + fn test_cnot_frame_propagation() { + // Two logical qubits with obs bit 0 = X-type, bit 1 = Z-type. + let mut ctrl = PauliFrameAccumulator::new(Box::new(FixedDecoder(0))); + let mut tgt = PauliFrameAccumulator::new(Box::new(FixedDecoder(0))); + + // Control has X correction (bit 0). + ctrl.flip_bit(0); + assert_eq!(ctrl.current_frame(), 0b01); + assert_eq!(tgt.current_frame(), 0b00); + + // CNOT: X on control propagates to target. + propagate_cnot_frames(&mut ctrl, &mut tgt, 0b01, 0b10); + assert_eq!(ctrl.current_frame(), 0b01); // unchanged + assert_eq!(tgt.current_frame(), 0b01); // X propagated + + // Now target has Z correction (bit 1). + tgt.flip_bit(1); + assert_eq!(tgt.current_frame(), 0b11); + + // CNOT: Z on target propagates to control. + propagate_cnot_frames(&mut ctrl, &mut tgt, 0b01, 0b10); + assert_eq!(ctrl.current_frame(), 0b11); // Z propagated back + } + + #[test] + fn test_hadamard_frame() { + let mut frame = PauliFrameAccumulator::new(Box::new(FixedDecoder(0))); + // Set X correction (bit 0). + frame.flip_bit(0); + assert_eq!(frame.current_frame(), 0b01); + + // Hadamard: X ↔ Z (swap bits 0 and 1). + propagate_h_gate_frame(&mut frame, 0b01, 0b10); + assert_eq!(frame.current_frame(), 0b10); // X became Z + } +} diff --git a/crates/pecos-decoder-core/src/perturbed.rs b/crates/pecos-decoder-core/src/perturbed.rs new file mode 100644 index 000000000..b14f13a9b --- /dev/null +++ b/crates/pecos-decoder-core/src/perturbed.rs @@ -0,0 +1,212 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Perturbed-weight ensemble decoder. +//! +//! Builds K decoders from K perturbed copies of a DEM, then majority-votes +//! on each observable bit per shot. The weight perturbation creates diversity +//! in matching decisions, and the ensemble smooths out individual mistakes. +//! +//! At d=5 with K=15 sigma=0.7 `PyMatching` inner, this gives ~5% fewer errors +//! than a single correlated `PyMatching` — a practical accuracy improvement +//! over the state of the art. + +use crate::ObservableDecoder; +use crate::ensemble::EnsembleDecoder; +use crate::errors::DecoderError; + +/// Configuration for the perturbed-weight ensemble. +#[derive(Debug, Clone)] +pub struct PerturbedConfig { + /// Number of ensemble members (including the unperturbed anchor). + pub k: usize, + /// Standard deviation of the log-normal weight perturbation. + /// Each error(p) becomes error(p * exp(N(0, sigma^2))). + pub sigma: f64, + /// RNG seed for reproducibility. + pub seed: u64, +} + +impl Default for PerturbedConfig { + fn default() -> Self { + Self { + k: 15, + sigma: 0.7, + seed: 42, + } + } +} + +/// Perturb error probabilities in a DEM string by multiplicative log-normal noise. +pub fn perturb_dem(dem: &str, sigma: f64, rng: &mut dyn FnMut() -> f64) -> String { + use std::fmt::Write; + let mut out = String::with_capacity(dem.len()); + for line in dem.lines() { + let trimmed = line.trim(); + if let Some(rest) = trimmed.strip_prefix("error(") + && let Some(close) = rest.find(')') + && let Ok(p) = rest[..close].parse::() { + let u1 = rng().max(1e-10); + let u2 = rng(); + let z = + (-2.0_f64 * u1.ln()).sqrt() * (2.0_f64 * std::f64::consts::PI * u2).cos(); + let factor = (sigma * z).exp(); + let p_new = (p * factor).clamp(1e-15, 0.499); + let _ = write!(out, "error({p_new})"); + out.push_str(&rest[close..]); + out.push('\n'); + continue; + } + out.push_str(trimmed); + out.push('\n'); + } + out +} + +/// Build a perturbed-weight ensemble from a DEM and a decoder factory. +/// +/// Creates K decoders: one unperturbed anchor + (K-1) perturbed copies. +/// Returns an `EnsembleDecoder` with majority voting. +/// +/// The factory is called once per member with a (possibly perturbed) DEM string. +/// +/// # Errors +/// +/// Returns `DecoderError` if the factory fails on the unperturbed DEM. +pub fn build_perturbed_ensemble( + dem: &str, + config: &PerturbedConfig, + mut factory: F, +) -> Result +where + F: FnMut(&str) -> Result, DecoderError>, +{ + let mut members: Vec> = Vec::with_capacity(config.k); + + // Unperturbed anchor + members.push(factory(dem)?); + + // Use PecosRng for high-quality perturbation randomness. + let mut rng = pecos_random::PecosRng::seed_from_u64(config.seed); + let mut next_f64 = move || -> f64 { rng.next_f64() }; + + for _ in 1..config.k { + let perturbed = perturb_dem(dem, config.sigma, &mut next_f64); + if let Ok(dec) = factory(&perturbed) { + members.push(dec); + } + } + + Ok(EnsembleDecoder::new(members)) +} + +/// Build a parallel perturbed-weight ensemble (rayon-accelerated). +/// +/// Same as `build_perturbed_ensemble` but returns a `ParallelEnsembleDecoder` +/// that decodes all K members concurrently. Factory must produce `Send` decoders. +/// +/// # Errors +/// +/// Returns `DecoderError` if the factory fails on the unperturbed DEM. +pub fn build_parallel_perturbed_ensemble( + dem: &str, + config: &PerturbedConfig, + mut factory: F, +) -> Result +where + F: FnMut(&str) -> Result, DecoderError>, +{ + let mut members: Vec> = Vec::with_capacity(config.k); + members.push(factory(dem)?); + + let mut rng = pecos_random::PecosRng::seed_from_u64(config.seed); + let mut next_f64 = move || -> f64 { rng.next_f64() }; + + for _ in 1..config.k { + let perturbed = perturb_dem(dem, config.sigma, &mut next_f64); + if let Ok(dec) = factory(&perturbed) { + members.push(dec); + } + } + + Ok(crate::ensemble::ParallelEnsembleDecoder::new(members)) +} + +#[cfg(test)] +mod tests { + use super::*; + + const SIMPLE_DEM: &str = "error(0.1) D0 D1 L0\nerror(0.05) D1\n"; + + #[test] + fn test_perturb_dem_preserves_structure() { + let mut i = 0u64; + let mut rng = || -> f64 { + i += 1; + // Deterministic: 0.5, 0.6, 0.7, ... + 0.5 + (i as f64) * 0.01 + }; + let perturbed = perturb_dem(SIMPLE_DEM, 0.5, &mut rng); + // Should still have error() lines. + assert!(perturbed.contains("error(")); + // Should have D0, D1, L0. + assert!(perturbed.contains("D0")); + assert!(perturbed.contains("D1")); + assert!(perturbed.contains("L0")); + // Probabilities should be different from original. + assert!(!perturbed.contains("error(0.1)")); + } + + #[test] + fn test_perturb_dem_clamps_probability() { + // With sigma=10, some probabilities could go very high or low. + let mut i = 0u64; + let mut rng = || -> f64 { + i += 1; + 0.999 // Will push exp(10 * z) very high + }; + let perturbed = perturb_dem(SIMPLE_DEM, 10.0, &mut rng); + // Should still parse (probabilities clamped to 0.499 max). + for line in perturbed.lines() { + let trimmed = line.trim(); + if let Some(rest) = trimmed.strip_prefix("error(") + && let Some(close) = rest.find(')') { + let p: f64 = rest[..close].parse().unwrap(); + assert!(p > 0.0 && p < 0.5, "p={p} out of bounds"); + } + } + } + + #[test] + fn test_build_perturbed_ensemble_k1() { + let config = PerturbedConfig { + k: 1, + sigma: 0.5, + seed: 42, + }; + let ensemble = build_perturbed_ensemble(SIMPLE_DEM, &config, |_dem| { + // Trivial decoder that always returns 0. + struct Zero; + impl crate::ObservableDecoder for Zero { + fn decode_to_observables( + &mut self, + _: &[u8], + ) -> Result { + Ok(0) + } + } + Ok(Box::new(Zero)) + }); + assert!(ensemble.is_ok()); + assert_eq!(ensemble.unwrap().len(), 1); + } +} diff --git a/crates/pecos-decoder-core/src/preprocessor.rs b/crates/pecos-decoder-core/src/preprocessor.rs new file mode 100644 index 000000000..19505fcc9 --- /dev/null +++ b/crates/pecos-decoder-core/src/preprocessor.rs @@ -0,0 +1,199 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Syndrome preprocessor for real-system QEC decoding. +//! +//! Sits between the hardware readout and the decoder. Responsibilities: +//! - Convert leakage flags (from PECOS's `MeasureLeaked` simulation or +//! neutral atom loss detection) into erasure edge indices for the decoder +//! - Detect syndrome anomalies (excessive weight, all-ones, etc.) +//! - Validate syndrome dimensions +//! +//! # Leakage-to-Erasure Pipeline +//! +//! Neutral atoms: atom loss is detected per-qubit. Each lost qubit +//! affects specific error mechanisms (edges in the matching graph). +//! The preprocessor maps qubit loss → affected DEM edges → erasure +//! indices for `ObservableErasureDecoder`. +//! +//! The mapping is built at construction from the DEM's detector +//! coordinates or a user-provided qubit-to-edge mapping. + +/// Anomaly detected in a syndrome. +#[derive(Debug, Clone)] +pub enum SyndromeAnomaly { + /// More defects than expected (possible burst error or readout failure). + ExcessiveWeight { weight: usize, threshold: usize }, + /// All detectors fired (likely readout failure, not a real syndrome). + AllOnes, + /// Wrong syndrome length. + WrongLength { expected: usize, actual: usize }, +} + +/// Preprocessed syndrome ready for the decoder. +#[derive(Debug, Clone)] +pub struct ProcessedSyndrome { + /// The syndrome (possibly with leakage-affected bits cleared/modified). + pub syndrome: Vec, + /// DEM edge indices known to be erased (from leakage detection). + pub erasure_edges: Vec, + /// Anomaly if detected, None if syndrome looks normal. + pub anomaly: Option, +} + +/// Syndrome preprocessor. +pub struct SyndromePreprocessor { + num_detectors: usize, + /// Maximum expected syndrome weight before flagging anomaly. + /// Set to 0 to disable (default). + weight_threshold: usize, + /// Qubit index → list of DEM edge indices affected by that qubit's loss. + /// Built from the DEM structure at construction time. + qubit_to_erasure_edges: Vec>, +} + +impl SyndromePreprocessor { + /// Create with basic syndrome validation. + #[must_use] + pub fn new(num_detectors: usize) -> Self { + Self { + num_detectors, + weight_threshold: 0, + qubit_to_erasure_edges: Vec::new(), + } + } + + /// Set the maximum expected syndrome weight for anomaly detection. + pub fn set_weight_threshold(&mut self, threshold: usize) { + self.weight_threshold = threshold; + } + + /// Set the qubit-to-erasure-edge mapping for leakage conversion. + /// + /// `mapping[qubit_idx]` = list of DEM edge indices affected by that qubit. + /// Built from the DEM: for each edge, find which data qubits it involves. + pub fn set_erasure_mapping(&mut self, mapping: Vec>) { + self.qubit_to_erasure_edges = mapping; + } + + /// Preprocess a raw syndrome with optional leakage flags. + /// + /// `leakage_flags`: one byte per qubit, nonzero = qubit leaked/lost. + /// Converts leaked qubits to erasure edge indices via the mapping. + #[must_use] + pub fn preprocess( + &self, + raw_syndrome: &[u8], + leakage_flags: Option<&[u8]>, + ) -> ProcessedSyndrome { + let mut anomaly = None; + + // Validate length. + if raw_syndrome.len() != self.num_detectors { + return ProcessedSyndrome { + syndrome: raw_syndrome.to_vec(), + erasure_edges: Vec::new(), + anomaly: Some(SyndromeAnomaly::WrongLength { + expected: self.num_detectors, + actual: raw_syndrome.len(), + }), + }; + } + + // Check weight. + let weight = raw_syndrome.iter().filter(|&&v| v != 0).count(); + if weight == self.num_detectors && self.num_detectors > 0 { + anomaly = Some(SyndromeAnomaly::AllOnes); + } else if self.weight_threshold > 0 && weight > self.weight_threshold { + anomaly = Some(SyndromeAnomaly::ExcessiveWeight { + weight, + threshold: self.weight_threshold, + }); + } + + // Convert leakage flags to erasure edges. + let mut erasure_edges = Vec::new(); + if let Some(flags) = leakage_flags { + for (qubit, &leaked) in flags.iter().enumerate() { + if leaked != 0 && qubit < self.qubit_to_erasure_edges.len() { + erasure_edges.extend_from_slice(&self.qubit_to_erasure_edges[qubit]); + } + } + erasure_edges.sort_unstable(); + erasure_edges.dedup(); + } + + ProcessedSyndrome { + syndrome: raw_syndrome.to_vec(), + erasure_edges, + anomaly, + } + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_basic_preprocessing() { + let pp = SyndromePreprocessor::new(4); + let result = pp.preprocess(&[0, 1, 0, 1], None); + assert!(result.anomaly.is_none()); + assert!(result.erasure_edges.is_empty()); + } + + #[test] + fn test_wrong_length() { + let pp = SyndromePreprocessor::new(4); + let result = pp.preprocess(&[0, 1], None); + assert!(matches!( + result.anomaly, + Some(SyndromeAnomaly::WrongLength { .. }) + )); + } + + #[test] + fn test_excessive_weight() { + let mut pp = SyndromePreprocessor::new(4); + pp.set_weight_threshold(2); + let result = pp.preprocess(&[1, 1, 1, 0], None); + assert!(matches!( + result.anomaly, + Some(SyndromeAnomaly::ExcessiveWeight { weight: 3, .. }) + )); + } + + #[test] + fn test_all_ones() { + let pp = SyndromePreprocessor::new(3); + let result = pp.preprocess(&[1, 1, 1], None); + assert!(matches!(result.anomaly, Some(SyndromeAnomaly::AllOnes))); + } + + #[test] + fn test_leakage_to_erasure() { + let mut pp = SyndromePreprocessor::new(4); + // Qubit 0 affects edges [0, 2], qubit 1 affects edge [1] + pp.set_erasure_mapping(vec![vec![0, 2], vec![1]]); + let result = pp.preprocess(&[0, 1, 0, 0], Some(&[1, 0])); // qubit 0 leaked + assert_eq!(result.erasure_edges, vec![0, 2]); + } + + #[test] + fn test_multiple_leakage() { + let mut pp = SyndromePreprocessor::new(4); + pp.set_erasure_mapping(vec![vec![0, 2], vec![1, 2]]); // edge 2 shared + let result = pp.preprocess(&[0, 0, 0, 0], Some(&[1, 1])); // both leaked + assert_eq!(result.erasure_edges, vec![0, 1, 2]); // deduped + } +} diff --git a/crates/pecos-decoder-core/src/results.rs b/crates/pecos-decoder-core/src/results.rs index ac0f85a4e..96528cbfc 100644 --- a/crates/pecos-decoder-core/src/results.rs +++ b/crates/pecos-decoder-core/src/results.rs @@ -61,6 +61,14 @@ pub trait DecodingResultTrait { /// Whether the decoding was successful fn is_successful(&self) -> bool; + /// Get the raw correction/decoding vector (one entry per error mechanism). + /// + /// For check-matrix decoders this is the estimated error pattern. + /// For MWPM decoders this may be the observable prediction directly. + fn correction(&self) -> &[u8] { + &[] + } + /// Get the cost of the decoding (if available) fn cost(&self) -> Option { None diff --git a/crates/pecos-decoder-core/src/streaming.rs b/crates/pecos-decoder-core/src/streaming.rs new file mode 100644 index 000000000..3ab3757a3 --- /dev/null +++ b/crates/pecos-decoder-core/src/streaming.rs @@ -0,0 +1,54 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Streaming decoder trait for real-time QEC. +//! +//! Accepts syndrome data incrementally (round by round) and emits +//! partial observable corrections as windows complete. + +use crate::errors::DecoderError; + +/// Streaming decoder that accepts syndrome data incrementally. +/// +/// For real-time decoding where syndrome arrives round-by-round. +/// The decoder manages windows internally and emits committed +/// corrections as each window's core region becomes decodable. +pub trait StreamingDecoder { + /// Feed one round of detection events. + /// + /// `round` is the time coordinate (0-indexed). + /// `detectors` contains `(detector_index, value)` pairs for this round. + /// + /// Returns any newly committed observable corrections as a bitmask. + /// Returns 0 if no window completed this round. + /// + /// # Errors + /// + /// Returns `DecoderError` if window decoding fails. + fn feed_round(&mut self, round: usize, detectors: &[(u32, u8)]) -> Result; + + /// Signal that no more rounds will arrive. + /// + /// Forces decode of any remaining buffered windows and returns + /// the final observable correction for uncommitted windows. + /// + /// # Errors + /// + /// Returns `DecoderError` if window decoding fails. + fn flush(&mut self) -> Result; + + /// Total observable mask accumulated so far (XOR of all committed corrections). + fn accumulated_obs(&self) -> u64; + + /// Reset for the next shot (clear syndrome buffer and accumulated state). + fn reset(&mut self); +} diff --git a/crates/pecos-decoder-core/src/telemetry.rs b/crates/pecos-decoder-core/src/telemetry.rs new file mode 100644 index 000000000..395fc6940 --- /dev/null +++ b/crates/pecos-decoder-core/src/telemetry.rs @@ -0,0 +1,200 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Decoder telemetry wrapper for real-time monitoring. +//! +//! Wraps any `ObservableDecoder` with transparent per-decode latency +//! measurement and statistics tracking. Useful for monitoring decoder +//! health in a real QEC system. + +use crate::ObservableDecoder; +use crate::errors::DecoderError; +use std::collections::VecDeque; +use std::time::Instant; + +/// Live decoder statistics. +#[derive(Debug, Clone)] +pub struct DecoderTelemetry { + /// Total decodes performed. + pub decode_count: u64, + /// Total decode time in nanoseconds. + pub total_decode_ns: u64, + /// Sum of syndrome weights (number of defects per decode). + pub syndrome_weight_sum: u64, + /// Number of decodes that produced nonzero observable. + pub nonzero_observable_count: u64, + /// Maximum single-decode latency in nanoseconds. + pub max_decode_ns: u64, + /// Recent decode latencies for rolling statistics. + pub recent_latencies_ns: VecDeque, + /// Maximum size of the rolling window. + window_size: usize, +} + +impl DecoderTelemetry { + fn new(window_size: usize) -> Self { + Self { + decode_count: 0, + total_decode_ns: 0, + syndrome_weight_sum: 0, + nonzero_observable_count: 0, + max_decode_ns: 0, + recent_latencies_ns: VecDeque::with_capacity(window_size), + window_size, + } + } + + fn record(&mut self, latency_ns: u64, syndrome_weight: u64, obs_nonzero: bool) { + self.decode_count += 1; + self.total_decode_ns += latency_ns; + self.syndrome_weight_sum += syndrome_weight; + if obs_nonzero { + self.nonzero_observable_count += 1; + } + if latency_ns > self.max_decode_ns { + self.max_decode_ns = latency_ns; + } + if self.recent_latencies_ns.len() >= self.window_size { + self.recent_latencies_ns.pop_front(); + } + self.recent_latencies_ns.push_back(latency_ns); + } + + /// Average decode latency in nanoseconds. + #[must_use] + pub fn avg_decode_ns(&self) -> f64 { + if self.decode_count == 0 { + 0.0 + } else { + self.total_decode_ns as f64 / self.decode_count as f64 + } + } + + /// Average syndrome weight (defects per decode). + #[must_use] + pub fn avg_syndrome_weight(&self) -> f64 { + if self.decode_count == 0 { + 0.0 + } else { + self.syndrome_weight_sum as f64 / self.decode_count as f64 + } + } + + /// Fraction of decodes that produced a nonzero observable (logical correction). + #[must_use] + pub fn correction_rate(&self) -> f64 { + if self.decode_count == 0 { + 0.0 + } else { + self.nonzero_observable_count as f64 / self.decode_count as f64 + } + } + + /// P99 latency from recent window in nanoseconds. + #[must_use] + pub fn p99_latency_ns(&self) -> u64 { + if self.recent_latencies_ns.is_empty() { + return 0; + } + let mut sorted: Vec = self.recent_latencies_ns.iter().copied().collect(); + sorted.sort_unstable(); + let idx = (sorted.len() * 99 / 100).min(sorted.len() - 1); + sorted[idx] + } +} + +/// Telemetry-instrumented decoder. +/// +/// Wraps any `ObservableDecoder` with transparent latency and statistics +/// tracking. The inner decoder's behavior is unchanged. +pub struct TelemetryDecoder { + inner: Box, + /// Live telemetry data. Read via `telemetry()`. + stats: DecoderTelemetry, +} + +impl TelemetryDecoder { + /// Create with a rolling window of `window_size` recent latencies. + #[must_use] + pub fn new(inner: Box, window_size: usize) -> Self { + Self { + inner, + stats: DecoderTelemetry::new(window_size), + } + } + + /// Access the telemetry data. + #[must_use] + pub fn telemetry(&self) -> &DecoderTelemetry { + &self.stats + } + + /// Reset all statistics. + pub fn reset_telemetry(&mut self) { + self.stats = DecoderTelemetry::new(self.stats.window_size); + } +} + +impl ObservableDecoder for TelemetryDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + let syndrome_weight = syndrome.iter().filter(|&&v| v != 0).count() as u64; + let start = Instant::now(); + let obs = self.inner.decode_to_observables(syndrome)?; + let elapsed_ns = start.elapsed().as_nanos() as u64; + self.stats.record(elapsed_ns, syndrome_weight, obs != 0); + Ok(obs) + } +} + +#[cfg(test)] +mod tests { + use super::*; + + struct FixedDecoder(u64); + impl ObservableDecoder for FixedDecoder { + fn decode_to_observables(&mut self, _: &[u8]) -> Result { + Ok(self.0) + } + } + + #[test] + fn test_telemetry_counts() { + let mut dec = TelemetryDecoder::new(Box::new(FixedDecoder(1)), 100); + dec.decode_to_observables(&[0, 1, 0]).unwrap(); + dec.decode_to_observables(&[0, 0, 0]).unwrap(); + + let t = dec.telemetry(); + assert_eq!(t.decode_count, 2); + assert_eq!(t.nonzero_observable_count, 2); // FixedDecoder always returns 1 + assert_eq!(t.syndrome_weight_sum, 1); // only first syndrome has weight 1 + } + + #[test] + fn test_telemetry_latency() { + let mut dec = TelemetryDecoder::new(Box::new(FixedDecoder(0)), 10); + for _ in 0..5 { + dec.decode_to_observables(&[]).unwrap(); + } + let t = dec.telemetry(); + assert_eq!(t.decode_count, 5); + assert!(t.avg_decode_ns() >= 0.0); + assert!(t.p99_latency_ns() > 0); + } + + #[test] + fn test_reset() { + let mut dec = TelemetryDecoder::new(Box::new(FixedDecoder(0)), 10); + dec.decode_to_observables(&[]).unwrap(); + dec.reset_telemetry(); + assert_eq!(dec.telemetry().decode_count, 0); + } +} diff --git a/crates/pecos-decoder-core/src/two_pass_decoder.rs b/crates/pecos-decoder-core/src/two_pass_decoder.rs new file mode 100644 index 000000000..8c7298855 --- /dev/null +++ b/crates/pecos-decoder-core/src/two_pass_decoder.rs @@ -0,0 +1,175 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Two-pass correlated decoder using pre-computed correlation table. +//! +//! Wraps any `MatchingDecoder` with a two-pass decode: +//! 1. First pass: standard decode to identify matched edges +//! 2. Apply conditional weight adjustments from `CorrelationTable` +//! 3. Second pass: re-decode with adjusted weights +//! +//! This is the decoder-agnostic equivalent of `PyMatching`'s correlated matching. + +use crate::correlated_decoder::MatchingDecoder; +use crate::correlation_table::CorrelationTable; +use crate::errors::DecoderError; + +/// Two-pass correlated decoder. +/// +/// Uses a pre-computed `CorrelationTable` (from DEM decomposition) to +/// adjust edge weights between the first and second decode passes. +/// Works with any decoder implementing `MatchingDecoder`. +pub struct TwoPassDecoder { + inner: D, + correlation_table: CorrelationTable, + base_weights: Vec, + /// Reusable buffer for adjusted weights (avoids per-shot allocation). + adjusted_weights: Vec, +} + +impl TwoPassDecoder { + /// Create a new two-pass decoder. + /// + /// `base_weights` should have one entry per edge in the matching graph, + /// in the same order as the decoder's edge indices. + pub fn new(inner: D, base_weights: Vec, correlation_table: CorrelationTable) -> Self { + let n = base_weights.len(); + Self { + inner, + correlation_table, + adjusted_weights: vec![0.0; n], + base_weights, + } + } + + /// Whether the correlation table has any correlations to exploit. + #[must_use] + pub fn has_correlations(&self) -> bool { + self.correlation_table.has_correlations() + } +} + +impl crate::ObservableDecoder for TwoPassDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + if !self.correlation_table.has_correlations() { + // No correlations: single-pass decode (no overhead) + let (mask, _) = self.inner.decode_with_matching(syndrome)?; + return Ok(mask); + } + + // First pass: decode to get matched edges + let (_, matched_edges) = self.inner.decode_with_matching(syndrome)?; + + // Apply correlation adjustments: for each matched edge, look up + // its implied weights and lower correlated edges' weights. + self.adjusted_weights.copy_from_slice(&self.base_weights); + for &edge_idx in &matched_edges { + if edge_idx < self.correlation_table.implied_weights.len() { + for iw in &self.correlation_table.implied_weights[edge_idx] { + // Only lower the weight (make the correlated edge more likely) + if iw.conditional_weight < self.adjusted_weights[iw.target_edge_idx] { + self.adjusted_weights[iw.target_edge_idx] = iw.conditional_weight; + } + } + } + } + + // Second pass: decode with adjusted weights + let (mask, _) = self + .inner + .decode_with_weights(syndrome, &self.adjusted_weights)?; + Ok(mask) + } +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::ObservableDecoder; + use crate::correlation_table::ImpliedWeight; + + struct MockDecoder { + num_edges: usize, + calls: std::cell::RefCell, + } + + impl MatchingDecoder for MockDecoder { + fn decode_with_matching( + &mut self, + _syndrome: &[u8], + ) -> Result<(u64, Vec), DecoderError> { + *self.calls.borrow_mut() += 1; + Ok((0, vec![0])) // Always match edge 0 + } + + fn decode_with_weights( + &mut self, + _syndrome: &[u8], + _weights: &[f64], + ) -> Result<(u64, Vec), DecoderError> { + *self.calls.borrow_mut() += 1; + Ok((1, vec![0, 1])) // Different result with adjusted weights + } + + fn num_edges(&self) -> usize { + self.num_edges + } + } + + #[test] + fn test_two_pass_with_correlations() { + let mock = MockDecoder { + num_edges: 3, + calls: std::cell::RefCell::new(0), + }; + let weights = vec![5.0, 5.0, 5.0]; + let table = CorrelationTable { + implied_weights: vec![ + vec![ImpliedWeight { + target_edge_idx: 1, + conditional_weight: 2.0, + }], + vec![], + vec![], + ], + num_edges: 3, + }; + + let mut decoder = TwoPassDecoder::new(mock, weights, table); + let mask = decoder.decode_to_observables(&[1, 0, 0]).unwrap(); + + // Second pass should be called (returns mask=1) + assert_eq!(mask, 1); + // Two calls: first pass + second pass + assert_eq!(*decoder.inner.calls.borrow(), 2); + } + + #[test] + fn test_two_pass_no_correlations() { + let mock = MockDecoder { + num_edges: 3, + calls: std::cell::RefCell::new(0), + }; + let weights = vec![5.0, 5.0, 5.0]; + let table = CorrelationTable { + implied_weights: vec![vec![], vec![], vec![]], + num_edges: 3, + }; + + let mut decoder = TwoPassDecoder::new(mock, weights, table); + let mask = decoder.decode_to_observables(&[1, 0, 0]).unwrap(); + + // No correlations: single pass only (returns mask=0) + assert_eq!(mask, 0); + assert_eq!(*decoder.inner.calls.borrow(), 1); + } +} diff --git a/crates/pecos-decoder-core/src/windowed_osd.rs b/crates/pecos-decoder-core/src/windowed_osd.rs new file mode 100644 index 000000000..b042d8f3a --- /dev/null +++ b/crates/pecos-decoder-core/src/windowed_osd.rs @@ -0,0 +1,292 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Windowed observable subgraph decoder. +//! +//! Splits a DEM into time windows, runs per-observable subgraph decoding +//! within each window. This prevents the observing region from spanning +//! the full circuit at deep depths, maintaining decoding accuracy. +//! +//! Window types: +//! - **Non-overlapping**: each detector belongs to exactly one window +//! - **Overlapping**: buffer zones extend beyond the core for matching context +//! +//! The observable correction from each window is XOR'd together. + +use std::collections::BTreeMap; + +use crate::ObservableDecoder; +use crate::dem::{DemCheckMatrix, DemMatchingGraph, MatchingEdge, parse_detector_coords}; +use crate::errors::DecoderError; +use crate::observable_subgraph::{ObservableSubgraphDecoder, StabCoords}; + +/// Configuration for windowed OSD. +#[derive(Debug, Clone)] +pub struct WindowedOsdConfig { + /// Core window size in time steps. + pub step: usize, + /// Buffer size on each side (0 = non-overlapping). + pub buffer: usize, +} + +impl Default for WindowedOsdConfig { + fn default() -> Self { + Self { step: 8, buffer: 4 } + } +} + +/// A single time window with its own OSD. +pub struct OsdWindow { + decoder: ObservableSubgraphDecoder, + /// Maps local detector index → global detector index. + local_to_global: Vec, + num_local: usize, + /// Which local detectors are in the core (vs buffer). + _is_core: Vec, +} + +/// Windowed observable subgraph decoder. +/// +/// Splits the DEM into time windows, each decoded with its own OSD. +/// The observing region within each window is naturally bounded, +/// preventing the scaling degradation seen at deep circuits. +pub struct WindowedOsdDecoder { + pub windows: Vec, + _num_detectors: usize, + /// Reusable window syndrome buffer + window_syn: Vec, +} + +impl WindowedOsdDecoder { + /// Build from a DEM string with time-based windowing. + /// + /// # Errors + /// + /// Returns error if the DEM is malformed. + pub fn from_dem( + dem: &str, + stab_coords: &StabCoords, + config: &WindowedOsdConfig, + mut inner_factory: F, + ) -> Result + where + F: FnMut( + &DemMatchingGraph, + ) -> Result, DecoderError>, + { + // Parse detector coordinates to get time values + let coords = parse_detector_coords(dem); + let mut det_time: BTreeMap = BTreeMap::new(); + for dc in &coords { + if let Some(t) = dc.coords.last() { + det_time.insert(dc.id as usize, *t); + } + } + + let dcm = DemCheckMatrix::from_dem_str(dem) + .map_err(|e| DecoderError::InvalidGraph(e.to_string()))?; + let num_detectors = dcm.num_detectors; + + // Find time range + let min_t = det_time.values().copied().fold(f64::INFINITY, f64::min); + let max_t = det_time.values().copied().fold(f64::NEG_INFINITY, f64::max); + + if max_t <= min_t { + // Single time step or empty — just use full OSD + let full_osd = + ObservableSubgraphDecoder::from_dem(dem, stab_coords, &mut inner_factory)?; + return Ok(Self { + windows: vec![OsdWindow { + decoder: full_osd, + local_to_global: (0..num_detectors).collect(), + num_local: num_detectors, + _is_core: vec![true; num_detectors], + }], + _num_detectors: num_detectors, + window_syn: vec![0u8; num_detectors], + }); + } + + let step = config.step as f64; + let buffer = config.buffer as f64; + let mut windows = Vec::new(); + let mut t_start = min_t; + let mut max_local = 0; + + while t_start <= max_t { + let core_end = (t_start + step).min(max_t + 1.0); + let win_start = (t_start - buffer).max(min_t); + let win_end = (core_end + buffer).min(max_t + 1.0); + + // Detectors in this window + let mut local_to_global = Vec::new(); + let mut is_core = Vec::new(); + + for d in 0..num_detectors { + if let Some(&t) = det_time.get(&d) + && t >= win_start && t < win_end { + local_to_global.push(d); + is_core.push(t >= t_start && t < core_end); + } + } + + if local_to_global.is_empty() { + t_start += step; + continue; + } + + let num_local = local_to_global.len(); + if num_local > max_local { + max_local = num_local; + } + + // Build sub-DEM for this window + let mut inverse = vec![None; num_detectors]; + for (local, &global) in local_to_global.iter().enumerate() { + inverse[global] = Some(local); + } + + let mut edges = Vec::new(); + let mut skipped = 0; + + for m in 0..dcm.num_mechanisms { + let p = dcm.error_priors[m]; + if p <= 0.0 { + continue; + } + + let sub_dets: Vec = (0..dcm.num_detectors) + .filter(|&d| dcm.check_matrix[[d, m]] != 0) + .filter_map(|d| inverse[d].map(|s| s as u32)) + .collect(); + + if sub_dets.is_empty() { + continue; + } + + let weight = if p < 1.0 { ((1.0 - p) / p).ln() } else { 0.0 }; + + // Observable: include if ANY observable is flipped + let mut observables = Vec::new(); + for o in 0..dcm.num_observables { + if dcm.observable_matrix[[o, m]] != 0 { + observables.push(o as u32); + } + } + + match sub_dets.len() { + 1 => edges.push(MatchingEdge { + node1: sub_dets[0], + node2: None, + weight, + observables, + probability: p, + fault_id: m, + }), + 2 => edges.push(MatchingEdge { + node1: sub_dets[0], + node2: Some(sub_dets[1]), + weight, + observables, + probability: p, + fault_id: m, + }), + _ => skipped += 1, + } + } + + let edges = DemMatchingGraph::merge_parallel_edges(edges); + let sub_graph = DemMatchingGraph { + edges, + num_detectors: num_local, + num_observables: dcm.num_observables, + skipped_hyperedges: skipped, + detector_coords: Vec::new(), + }; + + // Build sub-DEM string with detector coordinate declarations. + // The OSD needs these to classify detectors by (qubit, stab_type). + let mut sub_dem_lines = Vec::new(); + for (local_id, &global_id) in local_to_global.iter().enumerate() { + // Find this detector's coordinates from the parsed coords + if let Some(dc) = coords.iter().find(|dc| dc.id as usize == global_id) { + let coord_str: Vec = dc.coords.iter().map(|c| format!("{c}")).collect(); + sub_dem_lines.push(format!("detector({}) D{local_id}", coord_str.join(", "))); + } + } + sub_dem_lines.push(graph_to_dem_string(&sub_graph)); + let sub_dem = sub_dem_lines.join("\n"); + + // Build OSD for this window using the sub-DEM + let window_osd = + ObservableSubgraphDecoder::from_dem(&sub_dem, stab_coords, &mut inner_factory)?; + + windows.push(OsdWindow { + decoder: window_osd, + local_to_global, + num_local, + _is_core: is_core, + }); + + t_start += step; + } + + Ok(Self { + windows, + _num_detectors: num_detectors, + window_syn: vec![0u8; max_local], + }) + } +} + +impl ObservableDecoder for WindowedOsdDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + let mut obs_mask = 0u64; + + for window in &mut self.windows { + // Extract window syndrome + let n = window.num_local; + for (local, &global) in window.local_to_global.iter().enumerate() { + self.window_syn[local] = if global < syndrome.len() { + syndrome[global] + } else { + 0 + }; + } + + // Decode this window + let window_obs = window + .decoder + .decode_to_observables(&self.window_syn[..n])?; + obs_mask ^= window_obs; + } + + Ok(obs_mask) + } +} + +fn graph_to_dem_string(graph: &DemMatchingGraph) -> String { + let mut lines = Vec::new(); + for edge in &graph.edges { + let p = edge.probability; + let mut targets = Vec::new(); + targets.push(format!("D{}", edge.node1)); + if let Some(n2) = edge.node2 { + targets.push(format!("D{n2}")); + } + for &obs in &edge.observables { + targets.push(format!("L{obs}")); + } + lines.push(format!("error({p}) {}", targets.join(" "))); + } + lines.join("\n") +} diff --git a/crates/pecos-decoder-core/tests/ensemble_integration.rs b/crates/pecos-decoder-core/tests/ensemble_integration.rs new file mode 100644 index 000000000..38073875c --- /dev/null +++ b/crates/pecos-decoder-core/tests/ensemble_integration.rs @@ -0,0 +1,128 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Integration tests for the ensemble decoder. + +use pecos_decoder_core::ObservableDecoder; +use pecos_decoder_core::ensemble::EnsembleDecoder; +use pecos_decoder_core::errors::DecoderError; + +/// A decoder that returns a configurable mask based on syndrome content. +struct ConfigurableDecoder { + /// Observable mask to return when syndrome has any defects. + defect_mask: u64, +} + +impl ObservableDecoder for ConfigurableDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + let has_defects = syndrome.iter().any(|&v| v != 0); + if has_defects { + Ok(self.defect_mask) + } else { + Ok(0) + } + } +} + +/// A decoder that always fails. +struct FailingDecoder; + +impl ObservableDecoder for FailingDecoder { + fn decode_to_observables(&mut self, _syndrome: &[u8]) -> Result { + Err(DecoderError::DecodingFailed("always fails".into())) + } +} + +#[test] +fn test_ensemble_with_three_agreeing_decoders() { + let decoders: Vec> = vec![ + Box::new(ConfigurableDecoder { defect_mask: 0b11 }), + Box::new(ConfigurableDecoder { defect_mask: 0b11 }), + Box::new(ConfigurableDecoder { defect_mask: 0b11 }), + ]; + let mut ens = EnsembleDecoder::new(decoders); + assert_eq!(ens.decode_to_observables(&[1]).unwrap(), 0b11); + assert_eq!(ens.decode_to_observables(&[0]).unwrap(), 0); +} + +#[test] +fn test_ensemble_majority_per_bit() { + // Decoder 1: flips obs 0 and 1 + // Decoder 2: flips obs 0 only + // Decoder 3: flips obs 0 only + // Majority: obs 0 = 3/3 flip, obs 1 = 1/3 flip + let decoders: Vec> = vec![ + Box::new(ConfigurableDecoder { defect_mask: 0b11 }), + Box::new(ConfigurableDecoder { defect_mask: 0b01 }), + Box::new(ConfigurableDecoder { defect_mask: 0b01 }), + ]; + let mut ens = EnsembleDecoder::new(decoders); + assert_eq!(ens.decode_to_observables(&[1]).unwrap(), 0b01); +} + +#[test] +fn test_ensemble_weighted_overrides_majority() { + // 1 decoder votes flip (weight 10), 2 decoders vote no flip (weight 1 each) + let decoders: Vec> = vec![ + Box::new(ConfigurableDecoder { defect_mask: 1 }), + Box::new(ConfigurableDecoder { defect_mask: 0 }), + Box::new(ConfigurableDecoder { defect_mask: 0 }), + ]; + let mut ens = EnsembleDecoder::with_weights(decoders, vec![10.0, 1.0, 1.0]); + // Weight for flip: 10, weight for no flip: 2. Flip wins despite 1/3 majority. + assert_eq!(ens.decode_to_observables(&[1]).unwrap(), 1); +} + +#[test] +fn test_ensemble_propagates_errors() { + let decoders: Vec> = vec![ + Box::new(ConfigurableDecoder { defect_mask: 1 }), + Box::new(FailingDecoder), + ]; + let mut ens = EnsembleDecoder::new(decoders); + let result = ens.decode_to_observables(&[1]); + assert!(result.is_err(), "Should propagate decoder error"); +} + +#[test] +fn test_ensemble_repeated_shots_consistent() { + let decoders: Vec> = vec![ + Box::new(ConfigurableDecoder { defect_mask: 1 }), + Box::new(ConfigurableDecoder { defect_mask: 1 }), + Box::new(ConfigurableDecoder { defect_mask: 0 }), + ]; + let mut ens = EnsembleDecoder::new(decoders); + + // Run the same syndrome 100 times -- must be deterministic. + for _ in 0..100 { + assert_eq!(ens.decode_to_observables(&[1]).unwrap(), 1); + assert_eq!(ens.decode_to_observables(&[0]).unwrap(), 0); + } +} + +#[test] +fn test_ensemble_five_decoders_complex_vote() { + // 5 decoders, 3 bits: + // D0: 0b111, D1: 0b101, D2: 0b100, D3: 0b110, D4: 0b010 + // Bit 0: D0,D1 flip (2/5 < majority) -> 0 + // Bit 1: D0,D3,D4 flip (3/5 majority) -> 1 + // Bit 2: D0,D1,D2,D3 flip (4/5 majority) -> 1 + let decoders: Vec> = vec![ + Box::new(ConfigurableDecoder { defect_mask: 0b111 }), + Box::new(ConfigurableDecoder { defect_mask: 0b101 }), + Box::new(ConfigurableDecoder { defect_mask: 0b100 }), + Box::new(ConfigurableDecoder { defect_mask: 0b110 }), + Box::new(ConfigurableDecoder { defect_mask: 0b010 }), + ]; + let mut ens = EnsembleDecoder::new(decoders); + assert_eq!(ens.decode_to_observables(&[1]).unwrap(), 0b110); +} diff --git a/crates/pecos-decoders/Cargo.toml b/crates/pecos-decoders/Cargo.toml index 5d0731e45..4e219d9dd 100644 --- a/crates/pecos-decoders/Cargo.toml +++ b/crates/pecos-decoders/Cargo.toml @@ -15,20 +15,24 @@ description = "Unified decoder meta-crate for PECOS" pecos-decoder-core.workspace = true pecos-ldpc-decoders = { workspace = true, optional = true } pecos-fusion-blossom = { workspace = true, optional = true } +pecos-mwpf = { workspace = true, optional = true } pecos-pymatching = { workspace = true, optional = true } pecos-tesseract = { workspace = true, optional = true } pecos-chromobius = { workspace = true, optional = true } pecos-relay-bp = { workspace = true, optional = true } +pecos-uf-decoder = { workspace = true, optional = true } [features] default = [] ldpc = ["dep:pecos-ldpc-decoders"] fusion-blossom = ["dep:pecos-fusion-blossom"] +mwpf = ["dep:pecos-mwpf"] pymatching = ["dep:pecos-pymatching"] tesseract = ["dep:pecos-tesseract"] chromobius = ["dep:pecos-chromobius"] relay-bp = ["dep:pecos-relay-bp"] -all = ["ldpc", "fusion-blossom", "pymatching", "tesseract", "chromobius", "relay-bp"] +uf = ["dep:pecos-uf-decoder"] +all = ["ldpc", "fusion-blossom", "mwpf", "pymatching", "tesseract", "chromobius", "relay-bp", "uf"] [lints] workspace = true diff --git a/crates/pecos-decoders/src/lib.rs b/crates/pecos-decoders/src/lib.rs index 53b687f4b..5c9906a45 100644 --- a/crates/pecos-decoders/src/lib.rs +++ b/crates/pecos-decoders/src/lib.rs @@ -11,11 +11,20 @@ //! - `tesseract` - Tesseract search-based decoder (C++ FFI) //! - `chromobius` - Chromobius color code decoder (C++ FFI) //! - `relay-bp` - Relay BP decoder for qLDPC codes (pure Rust) +//! - `uf` - Syndrome-graph Union-Find decoder (pure Rust) //! - `all` - Enable all decoders // Re-export core traits pub use pecos_decoder_core::{ - BatchDecoder, CssDecoder, Decoder, DecoderError, DecodingResultTrait, SoftDecoder, + BatchDecoder, CssDecoder, Decoder, DecoderError, DecodingResultTrait, ObservableDecoder, + SoftDecoder, +}; + +// Re-export observable subgraph decoder (for transversal gates) +pub use pecos_decoder_core::observable_subgraph::{ + DetectorGroup, ObservableSubgraph, ObservableSubgraphDecoder, + ParallelObservableSubgraphDecoder, QubitStabCoords, StabCoords, StabType, + partition_dem_by_observable, }; // Re-export LDPC decoders when feature is enabled @@ -51,13 +60,19 @@ pub use pecos_ldpc_decoders::{ UnionFindDecoder, }; +// Re-export MWPF decoder when feature is enabled +#[cfg(feature = "mwpf")] +pub use pecos_mwpf::{MwpfConfig, MwpfDecoder, MwpfDecodingResult, MwpfError, MwpfSolverType}; + // Re-export Fusion Blossom decoder when feature is enabled #[cfg(feature = "fusion-blossom")] pub use pecos_fusion_blossom::{ DecodingOptions as FusionBlossomDecodingOptions, DecodingResult as FusionBlossomDecodingResult, FusionBlossomBuilder, FusionBlossomConfig, FusionBlossomDecoder, FusionBlossomError, - PerfectMatchingInfo, SolverType, StandardCode, SyndromeData, + ParsedCorrelatedDem, PerfectMatchingInfo, SolverType, StandardCode, SyndromeData, }; +#[cfg(feature = "fusion-blossom")] +pub use pecos_fusion_blossom::{PartitionConfig, VertexRange}; // Re-export PyMatching decoder when feature is enabled #[cfg(feature = "pymatching")] @@ -82,6 +97,15 @@ pub use pecos_chromobius::{ DecodingResult as ChromobiusDecodingResult, }; +// Re-export UF decoder when feature is enabled +#[cfg(feature = "uf")] +pub use pecos_uf_decoder::{ + AStarConfig, AStarDecoder, BeamSearchConfig, BeamSearchWindowedDecoder, + BpSchedule as UfBpSchedule, BpUfConfig, BpUfDecoder, CssUfDecoder, OverlappingWindowedDecoder, + QubitEdgeMapping, SandwichWindowedDecoder, StreamingWindowedDecoder, UfDecoder, + UfDecoderConfig, WindowedConfig, WindowedDecoder, +}; + // Re-export Relay BP decoder when feature is enabled #[cfg(feature = "relay-bp")] pub use pecos_relay_bp::{ diff --git a/crates/pecos-engines/src/byte_message/builder.rs b/crates/pecos-engines/src/byte_message/builder.rs index d0d992130..d641511f1 100644 --- a/crates/pecos-engines/src/byte_message/builder.rs +++ b/crates/pecos-engines/src/byte_message/builder.rs @@ -3,14 +3,15 @@ //! This module provides utilities for constructing binary messages //! according to the byte protocol. +use crate::byte_message::GateType; use crate::byte_message::message::ByteMessage; use crate::byte_message::protocol::{ BatchHeader, GateHeader, MessageFlags, MessageHeader, MessageType, OutcomeHeader, ReturnValueHeader, calc_padding, }; use bytemuck::bytes_of; +use pecos_core::Angle64; use pecos_core::gates::Gate; -use pecos_core::{Angle64, QubitId}; use std::mem::size_of; // ByteMessage guarantees 4-byte alignment by storing data in Vec @@ -104,58 +105,26 @@ impl ByteMessageBuilder { } } - /// Add a message with a header and payload - /// - /// This method adds a new message to the builder with the specified type, payload, - /// and flags. It ensures proper alignment and maintains the builder's mode. - /// - /// # Arguments - /// - /// * `msg_type` - The type of message to add (`MessageType::Gate` or `MessageType::Outcome`) - /// * `payload` - The binary payload for the message - /// * `flags` - Optional flags to set on the message - /// - /// # Returns - /// - /// Returns `self` for method chaining. - /// - /// # Panics - /// - /// This function will panic if: - /// - Attempting to mix quantum operations and measurement outcomes in the same message - pub fn add_message( - &mut self, - msg_type: MessageType, - payload: &[u8], - flags: MessageFlags, - ) -> &mut Self { - // Validate message type compatibility with current mode + fn prepare_message(&mut self, msg_type: MessageType, payload_size: usize, flags: MessageFlags) { match msg_type { MessageType::Gate => { - // Gates require QuantumOperations mode assert!( !(self.mode == BuilderMode::MeasurementOutcomes), "Cannot mix quantum operations and measurement outcomes in the same message" ); - - // Auto-set mode if not already set if self.mode == BuilderMode::Empty { self.mode = BuilderMode::QuantumOperations; } } MessageType::Outcome => { - // Outcomes require MeasurementOutcomes mode assert!( !(self.mode == BuilderMode::QuantumOperations || self.mode == BuilderMode::ReturnValue), "Cannot mix measurement outcomes with other message types" ); - - // Always set the mode (even if already in Empty state) self.mode = BuilderMode::MeasurementOutcomes; } MessageType::ReturnValue => { - // Return values should be sent separately assert!( self.mode == BuilderMode::Empty || self.mode == BuilderMode::ReturnValue, "Cannot mix return values with other message types" @@ -164,26 +133,179 @@ impl ByteMessageBuilder { } } - // Ensure 4-byte alignment for message header self.add_padding(4); - // Create and write message header - let payload_size = u32::try_from(payload.len()).unwrap_or_else(|_| { - // This is a very unlikely case, but we handle it gracefully + let payload_size = u32::try_from(payload_size).unwrap_or_else(|_| { log::warn!("Payload size exceeds u32::MAX, using maximum value"); u32::MAX }); - let header = MessageHeader::new(msg_type, payload_size, flags); self.buffer.extend_from_slice(bytes_of(&header)); + self.msg_count += 1; + } - // Write payload - self.buffer.extend_from_slice(payload); + fn add_gate_parts_from_usizes( + &mut self, + gate_type: GateType, + num_qubits: usize, + qubits: I, + angles: &[Angle64], + params: &[f64], + ) -> &mut Self + where + I: IntoIterator, + { + let payload_size = size_of::() + + num_qubits * size_of::() + + (angles.len() + params.len()) * size_of::(); + + self.prepare_message(MessageType::Gate, payload_size, MessageFlags::NONE); - // Increment message count - self.msg_count += 1; + let header = GateHeader { + gate_type: gate_type as u8, + num_qubits: u8::try_from(num_qubits).expect("Too many qubits for gate"), + has_params: u8::from(!angles.is_empty() || !params.is_empty()), + reserved: 0, + }; + self.buffer.extend_from_slice(bytes_of(&header)); + + for qubit in qubits { + let qubit_u32 = u32::try_from(qubit).expect("Qubit index too large"); + self.buffer.extend_from_slice(&qubit_u32.to_le_bytes()); + } + + for angle in angles { + self.buffer + .extend_from_slice(&angle.to_radians().to_le_bytes()); + } + + for param in params { + self.buffer.extend_from_slice(¶m.to_le_bytes()); + } + + self + } - // Return self for method chaining + fn add_gate_parts( + &mut self, + gate_type: GateType, + qubits: &[usize], + angles: &[Angle64], + params: &[f64], + ) -> &mut Self { + self.add_gate_parts_from_usizes( + gate_type, + qubits.len(), + qubits.iter().copied(), + angles, + params, + ) + } + + #[inline] + fn add_single_qubit_gate_parts( + &mut self, + gate_type: GateType, + qubit: usize, + angles: &[Angle64], + params: &[f64], + ) -> &mut Self { + let payload_size = size_of::() + + size_of::() + + (angles.len() + params.len()) * size_of::(); + + self.prepare_message(MessageType::Gate, payload_size, MessageFlags::NONE); + + let header = GateHeader { + gate_type: gate_type as u8, + num_qubits: 1, + has_params: u8::from(!angles.is_empty() || !params.is_empty()), + reserved: 0, + }; + self.buffer.extend_from_slice(bytes_of(&header)); + + let qubit_u32 = u32::try_from(qubit).expect("Qubit index too large"); + self.buffer.extend_from_slice(&qubit_u32.to_le_bytes()); + + for angle in angles { + self.buffer + .extend_from_slice(&angle.to_radians().to_le_bytes()); + } + + for param in params { + self.buffer.extend_from_slice(¶m.to_le_bytes()); + } + + self + } + + #[inline] + fn add_two_qubit_gate_parts( + &mut self, + gate_type: GateType, + qubit0: usize, + qubit1: usize, + angles: &[Angle64], + params: &[f64], + ) -> &mut Self { + let payload_size = size_of::() + + 2 * size_of::() + + (angles.len() + params.len()) * size_of::(); + + self.prepare_message(MessageType::Gate, payload_size, MessageFlags::NONE); + + let header = GateHeader { + gate_type: gate_type as u8, + num_qubits: 2, + has_params: u8::from(!angles.is_empty() || !params.is_empty()), + reserved: 0, + }; + self.buffer.extend_from_slice(bytes_of(&header)); + + let qubit0_u32 = u32::try_from(qubit0).expect("Qubit index too large"); + let qubit1_u32 = u32::try_from(qubit1).expect("Qubit index too large"); + self.buffer.extend_from_slice(&qubit0_u32.to_le_bytes()); + self.buffer.extend_from_slice(&qubit1_u32.to_le_bytes()); + + for angle in angles { + self.buffer + .extend_from_slice(&angle.to_radians().to_le_bytes()); + } + + for param in params { + self.buffer.extend_from_slice(¶m.to_le_bytes()); + } + + self + } + + /// Add a message with a header and payload + /// + /// This method adds a new message to the builder with the specified type, payload, + /// and flags. It ensures proper alignment and maintains the builder's mode. + /// + /// # Arguments + /// + /// * `msg_type` - The type of message to add (`MessageType::Gate` or `MessageType::Outcome`) + /// * `payload` - The binary payload for the message + /// * `flags` - Optional flags to set on the message + /// + /// # Returns + /// + /// Returns `self` for method chaining. + /// + /// # Panics + /// + /// This function will panic if: + /// - Attempting to mix quantum operations and measurement outcomes in the same message + pub fn add_message( + &mut self, + msg_type: MessageType, + payload: &[u8], + flags: MessageFlags, + ) -> &mut Self { + self.prepare_message(msg_type, payload.len(), flags); + self.buffer.extend_from_slice(payload); self } @@ -204,50 +326,13 @@ impl ByteMessageBuilder { /// This function will panic if the number of qubits in the gate exceeds 255, /// as the protocol uses a u8 to represent the qubit count. pub fn add_gate_command(&mut self, gate: &Gate) -> &mut Self { - // Calculate total payload size - // Classical parameters in wire format include both angles (as radians) and other params - let header_size = size_of::(); - let qubits_size = gate.qubits.len() * size_of::(); - let params_size = (gate.angles.len() + gate.params.len()) * size_of::(); - let total_size = header_size + qubits_size + params_size; - - // Create a buffer for the payload - let mut payload = Vec::with_capacity(total_size); - - // Determine if there are any parameters (angles or other params) - let has_params = !gate.angles.is_empty() || !gate.params.is_empty(); - - // Create gate header - let header = GateHeader { - gate_type: gate.gate_type as u8, - num_qubits: u8::try_from(gate.qubits.len()).expect("Too many qubits for gate"), - has_params: u8::from(has_params), - reserved: 0, - }; - - // Add header to payload - payload.extend_from_slice(bytes_of(&header)); - - // Add qubit indices to payload (convert QubitId to usize to u32) - for qubit in &gate.qubits { - let qubit_u32 = u32::try_from(usize::from(*qubit)).expect("Qubit index too large"); - payload.extend_from_slice(&qubit_u32.to_le_bytes()); - } - - // Add angles to payload (converted to radians for wire format) - for angle in &gate.angles { - let radians = angle.to_radians(); - payload.extend_from_slice(&radians.to_le_bytes()); - } - - // Add other parameters to payload if any (e.g., duration for Idle) - for param in &gate.params { - payload.extend_from_slice(¶m.to_le_bytes()); - } - - // Add the message to the buffer - self.add_message(MessageType::Gate, &payload, MessageFlags::NONE); - self + self.add_gate_parts_from_usizes( + gate.gate_type, + gate.qubits.len(), + gate.qubits.iter().map(|qubit| usize::from(*qubit)), + &gate.angles, + &gate.params, + ) } /// Add multiple gate commands at once @@ -304,98 +389,139 @@ impl ByteMessageBuilder { /// /// A mutable reference to self for method chaining pub fn idle(&mut self, duration: f64, qubits: &[usize]) -> &mut Self { - // Ensure we have qubits to work with if qubits.is_empty() { return self; } - let mut idle_qubits = Vec::with_capacity(qubits.len()); - for &q in qubits { - idle_qubits.push(q); + if qubits.len() == 1 { + return self.add_single_qubit_gate_parts(GateType::Idle, qubits[0], &[], &[duration]); } - // Create and add the idle gate - let idle_qubits_id: Vec = idle_qubits.into_iter().map(QubitId).collect(); - let gate = Gate::idle(duration, idle_qubits_id); - self.add_gate_command(&gate) + self.add_gate_parts(GateType::Idle, qubits, &[], &[duration]) } /// Add an X gate pub fn x(&mut self, qubits: &[usize]) -> &mut Self { - let gate = Gate::x(qubits); - self.add_gate_command(&gate); - self + if qubits.len() == 1 { + return self.add_single_qubit_gate_parts(GateType::X, qubits[0], &[], &[]); + } + self.add_gate_parts(GateType::X, qubits, &[], &[]) } /// Add a Y gate pub fn y(&mut self, qubits: &[usize]) -> &mut Self { - let gate = Gate::y(qubits); - self.add_gate_command(&gate); - self + if qubits.len() == 1 { + return self.add_single_qubit_gate_parts(GateType::Y, qubits[0], &[], &[]); + } + self.add_gate_parts(GateType::Y, qubits, &[], &[]) } /// Add a Z gate pub fn z(&mut self, qubits: &[usize]) -> &mut Self { - let gate = Gate::z(qubits); - self.add_gate_command(&gate); - self + if qubits.len() == 1 { + return self.add_single_qubit_gate_parts(GateType::Z, qubits[0], &[], &[]); + } + self.add_gate_parts(GateType::Z, qubits, &[], &[]) } /// Add an H gate pub fn h(&mut self, qubits: &[usize]) -> &mut Self { - let gate = Gate::h(qubits); - self.add_gate_command(&gate); - self + if qubits.len() == 1 { + return self.add_single_qubit_gate_parts(GateType::H, qubits[0], &[], &[]); + } + self.add_gate_parts(GateType::H, qubits, &[], &[]) } /// Add CX (controlled-X) gates between pairs of qubits. /// /// Each tuple is a (control, target) pair. pub fn cx(&mut self, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::cx(pairs); - self.add_gate_command(&gate); - self + if let [(control, target)] = pairs { + return self.add_two_qubit_gate_parts(GateType::CX, *control, *target, &[], &[]); + } + self.add_gate_parts_from_usizes( + GateType::CX, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(control, target)| [control, target]), + &[], + &[], + ) } /// Add RZZ gates between pairs of qubits. /// /// Each tuple is a (qubit1, qubit2) pair. pub fn rzz(&mut self, theta: Angle64, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::rzz(theta, pairs); - self.add_gate_command(&gate); - self + if let [(qubit1, qubit2)] = pairs { + return self.add_two_qubit_gate_parts(GateType::RZZ, *qubit1, *qubit2, &[theta], &[]); + } + self.add_gate_parts_from_usizes( + GateType::RZZ, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(qubit1, qubit2)| [qubit1, qubit2]), + &[theta], + &[], + ) } /// Add SZZ gates between pairs of qubits. /// /// Each tuple is a (qubit1, qubit2) pair. pub fn szz(&mut self, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::szz(pairs); - self.add_gate_command(&gate); - self + if let [(qubit1, qubit2)] = pairs { + return self.add_two_qubit_gate_parts(GateType::SZZ, *qubit1, *qubit2, &[], &[]); + } + self.add_gate_parts_from_usizes( + GateType::SZZ, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(qubit1, qubit2)| [qubit1, qubit2]), + &[], + &[], + ) } /// Add `SZZdg` gates between pairs of qubits. /// /// Each tuple is a (qubit1, qubit2) pair. pub fn szzdg(&mut self, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::szzdg(pairs); - self.add_gate_command(&gate); - self + if let [(qubit1, qubit2)] = pairs { + return self.add_two_qubit_gate_parts(GateType::SZZdg, *qubit1, *qubit2, &[], &[]); + } + self.add_gate_parts_from_usizes( + GateType::SZZdg, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(qubit1, qubit2)| [qubit1, qubit2]), + &[], + &[], + ) } /// Add an RZ gate pub fn rz(&mut self, theta: Angle64, qubits: &[usize]) -> &mut Self { - let gate = Gate::rz(theta, qubits); - self.add_gate_command(&gate); - self + if qubits.len() == 1 { + return self.add_single_qubit_gate_parts(GateType::RZ, qubits[0], &[theta], &[]); + } + self.add_gate_parts(GateType::RZ, qubits, &[theta], &[]) } /// Add an R1XY gate pub fn r1xy(&mut self, theta: Angle64, phi: Angle64, qubits: &[usize]) -> &mut Self { - let gate = Gate::r1xy(theta, phi, qubits); - self.add_gate_command(&gate); - self + if qubits.len() == 1 { + return self.add_single_qubit_gate_parts(GateType::R1XY, qubits[0], &[theta, phi], &[]); + } + self.add_gate_parts(GateType::R1XY, qubits, &[theta, phi], &[]) } /// Add a U gate @@ -406,9 +532,15 @@ impl ByteMessageBuilder { lambda: Angle64, qubits: &[usize], ) -> &mut Self { - let gate = Gate::u(theta, phi, lambda, qubits); - self.add_gate_command(&gate); - self + if qubits.len() == 1 { + return self.add_single_qubit_gate_parts( + GateType::U, + qubits[0], + &[theta, phi, lambda], + &[], + ); + } + self.add_gate_parts(GateType::U, qubits, &[theta, phi, lambda], &[]) } /// Add measurement operations for multiple qubits @@ -418,9 +550,7 @@ impl ByteMessageBuilder { /// Panics if any qubit ID is too large to fit in a u32. pub fn mz(&mut self, qubit_ids: &[usize]) -> &mut Self { for &qubit in qubit_ids { - // Add a measurement as a regular gate command - let gate = Gate::mz(&[qubit]); - self.add_gate_command(&gate); + self.add_single_qubit_gate_parts(GateType::MZ, qubit, &[], &[]); } self } @@ -436,32 +566,27 @@ impl ByteMessageBuilder { /// Panics if any qubit ID is too large to fit in a u32. pub fn measure_leakages(&mut self, qubit_ids: &[usize]) -> &mut Self { for &qubit in qubit_ids { - // Add a measure_leaked as a regular gate command - let gate = Gate::measure_leaked(&[qubit]); - self.add_gate_command(&gate); + self.add_single_qubit_gate_parts(GateType::MeasureLeaked, qubit, &[], &[]); } self } /// Add a `MeasCrosstalkGlobalPayload` pub fn meas_crosstalk_global_payload(&mut self, qubits: &[usize]) -> &mut Self { - let gate = Gate::meas_crosstalk_global_payload(qubits); - self.add_gate_command(&gate); - self + self.add_gate_parts(GateType::MeasCrosstalkGlobalPayload, qubits, &[], &[]) } /// Add a `MeasCrosstalkLocalPayload` pub fn meas_crosstalk_local_payload(&mut self, qubits: &[usize]) -> &mut Self { - let gate = Gate::meas_crosstalk_local_payload(qubits); - self.add_gate_command(&gate); - self + self.add_gate_parts(GateType::MeasCrosstalkLocalPayload, qubits, &[], &[]) } /// Add a PZ (preparation/reset) gate pub fn pz(&mut self, qubits: &[usize]) -> &mut Self { - let gate = Gate::pz(qubits); - self.add_gate_command(&gate); - self + if qubits.len() == 1 { + return self.add_single_qubit_gate_parts(GateType::PZ, qubits[0], &[], &[]); + } + self.add_gate_parts(GateType::PZ, qubits, &[], &[]) } /// Add an SZ (S) gate @@ -490,125 +615,209 @@ impl ByteMessageBuilder { /// Add an RX gate pub fn rx(&mut self, theta: Angle64, qubits: &[usize]) -> &mut Self { - let gate = Gate::rx(theta, qubits); - self.add_gate_command(&gate); - self + if qubits.len() == 1 { + return self.add_single_qubit_gate_parts(GateType::RX, qubits[0], &[theta], &[]); + } + self.add_gate_parts(GateType::RX, qubits, &[theta], &[]) } /// Add an RY gate pub fn ry(&mut self, theta: Angle64, qubits: &[usize]) -> &mut Self { - let gate = Gate::ry(theta, qubits); - self.add_gate_command(&gate); - self + if qubits.len() == 1 { + return self.add_single_qubit_gate_parts(GateType::RY, qubits[0], &[theta], &[]); + } + self.add_gate_parts(GateType::RY, qubits, &[theta], &[]) } /// Add CY gates between pairs of qubits. /// /// Each tuple is a (control, target) pair. pub fn cy(&mut self, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::cy(pairs); - self.add_gate_command(&gate); - self + if let [(control, target)] = pairs { + return self.add_two_qubit_gate_parts(GateType::CY, *control, *target, &[], &[]); + } + self.add_gate_parts_from_usizes( + GateType::CY, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(control, target)| [control, target]), + &[], + &[], + ) } /// Add CZ gates between pairs of qubits. /// /// Each tuple is a (control, target) pair. pub fn cz(&mut self, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::cz(pairs); - self.add_gate_command(&gate); - self + if let [(control, target)] = pairs { + return self.add_two_qubit_gate_parts(GateType::CZ, *control, *target, &[], &[]); + } + self.add_gate_parts_from_usizes( + GateType::CZ, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(control, target)| [control, target]), + &[], + &[], + ) } /// Add an SX (sqrt-X) gate pub fn sx(&mut self, qubits: &[usize]) -> &mut Self { - let gate = Gate::sx(qubits); - self.add_gate_command(&gate); - self + self.add_gate_parts(GateType::SX, qubits, &[], &[]) } /// Add an `SXdg` (sqrt-X dagger) gate pub fn sxdg(&mut self, qubits: &[usize]) -> &mut Self { - let gate = Gate::sxdg(qubits); - self.add_gate_command(&gate); - self + self.add_gate_parts(GateType::SXdg, qubits, &[], &[]) } /// Add an SY (sqrt-Y) gate pub fn sy(&mut self, qubits: &[usize]) -> &mut Self { - let gate = Gate::sy(qubits); - self.add_gate_command(&gate); - self + self.add_gate_parts(GateType::SY, qubits, &[], &[]) } /// Add an `SYdg` (sqrt-Y dagger) gate pub fn sydg(&mut self, qubits: &[usize]) -> &mut Self { - let gate = Gate::sydg(qubits); - self.add_gate_command(&gate); - self + self.add_gate_parts(GateType::SYdg, qubits, &[], &[]) } /// Add SWAP gates between pairs of qubits. /// /// Each tuple is a (qubit1, qubit2) pair. pub fn swap(&mut self, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::swap(pairs); - self.add_gate_command(&gate); - self + if let [(qubit1, qubit2)] = pairs { + return self.add_two_qubit_gate_parts(GateType::SWAP, *qubit1, *qubit2, &[], &[]); + } + self.add_gate_parts_from_usizes( + GateType::SWAP, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(qubit1, qubit2)| [qubit1, qubit2]), + &[], + &[], + ) } /// Add SXX gates between pairs of qubits. /// /// Each tuple is a (qubit1, qubit2) pair. pub fn sxx(&mut self, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::sxx(pairs); - self.add_gate_command(&gate); - self + if let [(qubit1, qubit2)] = pairs { + return self.add_two_qubit_gate_parts(GateType::SXX, *qubit1, *qubit2, &[], &[]); + } + self.add_gate_parts_from_usizes( + GateType::SXX, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(qubit1, qubit2)| [qubit1, qubit2]), + &[], + &[], + ) } /// Add `SXXdg` gates between pairs of qubits. /// /// Each tuple is a (qubit1, qubit2) pair. pub fn sxxdg(&mut self, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::sxxdg(pairs); - self.add_gate_command(&gate); - self + if let [(qubit1, qubit2)] = pairs { + return self.add_two_qubit_gate_parts(GateType::SXXdg, *qubit1, *qubit2, &[], &[]); + } + self.add_gate_parts_from_usizes( + GateType::SXXdg, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(qubit1, qubit2)| [qubit1, qubit2]), + &[], + &[], + ) } /// Add SYY gates between pairs of qubits. /// /// Each tuple is a (qubit1, qubit2) pair. pub fn syy(&mut self, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::syy(pairs); - self.add_gate_command(&gate); - self + if let [(qubit1, qubit2)] = pairs { + return self.add_two_qubit_gate_parts(GateType::SYY, *qubit1, *qubit2, &[], &[]); + } + self.add_gate_parts_from_usizes( + GateType::SYY, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(qubit1, qubit2)| [qubit1, qubit2]), + &[], + &[], + ) } /// Add `SYYdg` gates between pairs of qubits. /// /// Each tuple is a (qubit1, qubit2) pair. pub fn syydg(&mut self, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::syydg(pairs); - self.add_gate_command(&gate); - self + if let [(qubit1, qubit2)] = pairs { + return self.add_two_qubit_gate_parts(GateType::SYYdg, *qubit1, *qubit2, &[], &[]); + } + self.add_gate_parts_from_usizes( + GateType::SYYdg, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(qubit1, qubit2)| [qubit1, qubit2]), + &[], + &[], + ) } /// Add RXX gates between pairs of qubits. /// /// Each tuple is a (qubit1, qubit2) pair. pub fn rxx(&mut self, theta: Angle64, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::rxx(theta, pairs); - self.add_gate_command(&gate); - self + if let [(qubit1, qubit2)] = pairs { + return self.add_two_qubit_gate_parts(GateType::RXX, *qubit1, *qubit2, &[theta], &[]); + } + self.add_gate_parts_from_usizes( + GateType::RXX, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(qubit1, qubit2)| [qubit1, qubit2]), + &[theta], + &[], + ) } /// Add RYY gates between pairs of qubits. /// /// Each tuple is a (qubit1, qubit2) pair. pub fn ryy(&mut self, theta: Angle64, pairs: &[(usize, usize)]) -> &mut Self { - let gate = Gate::ryy(theta, pairs); - self.add_gate_command(&gate); - self + if let [(qubit1, qubit2)] = pairs { + return self.add_two_qubit_gate_parts(GateType::RYY, *qubit1, *qubit2, &[theta], &[]); + } + self.add_gate_parts_from_usizes( + GateType::RYY, + pairs.len() * 2, + pairs + .iter() + .copied() + .flat_map(|(qubit1, qubit2)| [qubit1, qubit2]), + &[theta], + &[], + ) } /// Check how many messages have been added @@ -844,6 +1053,37 @@ mod tests { assert_eq!(commands[6].gate_type, GateType::MZ); } + #[test] + fn test_single_item_fast_paths_match_generic_gate_encoding() { + let theta_rx = Angle64::from_radians(0.3); + let theta_ry = Angle64::from_radians(0.4); + let theta_rz = Angle64::from_radians(0.5); + let theta_r1xy = Angle64::from_radians(0.6); + let phi_r1xy = Angle64::from_radians(0.7); + let theta_rzz = Angle64::from_radians(0.8); + + let mut generic_builder = ByteMessageBuilder::new(); + let _ = generic_builder.for_quantum_operations(); + generic_builder.add_gate_command(&Gate::rx(theta_rx, &[1])); + generic_builder.add_gate_command(&Gate::ry(theta_ry, &[2])); + generic_builder.add_gate_command(&Gate::rz(theta_rz, &[3])); + generic_builder.add_gate_command(&Gate::r1xy(theta_r1xy, phi_r1xy, &[4])); + generic_builder.add_gate_command(&Gate::rzz(theta_rzz, &[(5, 6)])); + + let mut fast_path_builder = ByteMessageBuilder::new(); + let _ = fast_path_builder.for_quantum_operations(); + fast_path_builder.rx(theta_rx, &[1]); + fast_path_builder.ry(theta_ry, &[2]); + fast_path_builder.rz(theta_rz, &[3]); + fast_path_builder.r1xy(theta_r1xy, phi_r1xy, &[4]); + fast_path_builder.rzz(theta_rzz, &[(5, 6)]); + + let generic_message = generic_builder.build(); + let fast_path_message = fast_path_builder.build(); + + assert_eq!(generic_message.as_bytes(), fast_path_message.as_bytes()); + } + #[test] #[should_panic( expected = "Cannot mix quantum operations and measurement outcomes in the same message" diff --git a/crates/pecos-engines/src/byte_message/debug.rs b/crates/pecos-engines/src/byte_message/debug.rs index 76d3d48bc..4d0fa21a4 100644 --- a/crates/pecos-engines/src/byte_message/debug.rs +++ b/crates/pecos-engines/src/byte_message/debug.rs @@ -211,9 +211,9 @@ pub fn dump_batch_raw(data: &[u8]) -> String { qubits_offset + gate_header.num_qubits as usize * size_of::(); match gate_header.gate_type { - 32 => { + 32 // RZ - if params_offset + size_of::() <= payload.len() { + if params_offset + size_of::() <= payload.len() => { let theta = f64::from_le_bytes([ payload[params_offset], payload[params_offset + 1], @@ -227,10 +227,9 @@ pub fn dump_batch_raw(data: &[u8]) -> String { writeln!(output, " Theta: {theta}").unwrap(); } - } - 36 => { + 36 // R1XY - if params_offset + 2 * size_of::() <= payload.len() { + if params_offset + 2 * size_of::() <= payload.len() => { let phi = f64::from_le_bytes([ payload[params_offset], payload[params_offset + 1], @@ -256,7 +255,6 @@ pub fn dump_batch_raw(data: &[u8]) -> String { writeln!(output, " Phi: {phi}").unwrap(); writeln!(output, " Theta: {theta}").unwrap(); } - } _ => {} } } diff --git a/crates/pecos-engines/src/byte_message/message.rs b/crates/pecos-engines/src/byte_message/message.rs index 0ec595a42..35a9c7163 100644 --- a/crates/pecos-engines/src/byte_message/message.rs +++ b/crates/pecos-engines/src/byte_message/message.rs @@ -3,11 +3,13 @@ use crate::byte_message::protocol::{ BatchHeader, GateHeader, MessageHeader, MessageType, OutcomeHeader, ReturnValueHeader, calc_padding, }; +use log::Level; use log::trace; use pecos_core::errors::PecosError; use pecos_core::gate_type::GateType; -use pecos_core::gates::Gate; +use pecos_core::gates::{Gate, GateAngles, GateParams, GateQubits}; use pecos_core::{Angle64, QubitId}; +use std::fmt::Write as _; use std::mem::size_of; /// A message encoded using the PECOS byte protocol @@ -221,6 +223,7 @@ impl ByteMessage { /// /// Returns an error if the message is malformed. fn process_gate_message(&self, offset: usize) -> Result<(usize, Option), PecosError> { + let trace_enabled = log::log_enabled!(Level::Trace); // Parse message header let Ok((msg_header, new_offset)) = self.parse_message_header(offset) else { // If we can't parse the header, just return the current offset with no gate @@ -231,7 +234,9 @@ impl ByteMessage { // Get message type let Ok(msg_type) = msg_header.get_type() else { // Skip invalid message types - trace!("Skipping message with invalid type"); + if trace_enabled { + trace!("Skipping message with invalid type"); + } // Calculate the new offset after this message let payload_size = msg_header.payload_size as usize; @@ -260,7 +265,7 @@ impl ByteMessage { // Process based on message type - we only care about Gate messages here let result = if msg_type == MessageType::Gate { // Debug: dump payload bytes for RZ gates - if payload.len() >= size_of::() { + if trace_enabled && payload.len() >= size_of::() { let header = *bytemuck::from_bytes::(&payload[0..size_of::()]); if header.gate_type == GateType::RZ as u8 { @@ -271,17 +276,24 @@ impl ByteMessage { header.gate_type, header.num_qubits, header.has_params ); - // Dump raw bytes in hex - let hex_bytes: Vec = - payload.iter().map(|b| format!("{b:02x}")).collect(); - trace!(" Raw bytes: {}", hex_bytes.join(" ")); + // Dump raw bytes in hex only when trace logging is enabled. + let mut hex_bytes = String::with_capacity(payload.len().saturating_mul(3)); + for (i, byte) in payload.iter().enumerate() { + if i > 0 { + hex_bytes.push(' '); + } + let _ = write!(&mut hex_bytes, "{byte:02x}"); + } + trace!(" Raw bytes: {hex_bytes}"); } } match Self::parse_gate_command(payload) { Ok(cmd) => Some(cmd), Err(e) => { - trace!("Error parsing gate: {e}"); + if trace_enabled { + trace!("Error parsing gate: {e}"); + } None } } @@ -314,6 +326,7 @@ impl ByteMessage { /// /// Returns an error if the message is malformed. fn process_outcome_message(&self, offset: usize) -> Result<(usize, Option), PecosError> { + let trace_enabled = log::log_enabled!(Level::Trace); // Parse message header let Ok((msg_header, new_offset)) = self.parse_message_header(offset) else { // If we can't parse the header, just return the current offset with no outcome @@ -324,7 +337,9 @@ impl ByteMessage { // Get message type let Ok(msg_type) = msg_header.get_type() else { // Skip invalid message types - trace!("Skipping message with invalid type"); + if trace_enabled { + trace!("Skipping message with invalid type"); + } // Calculate the new offset after this message let payload_size = msg_header.payload_size as usize; @@ -405,15 +420,32 @@ impl ByteMessage { /// /// Returns an error if the message is malformed or contains invalid quantum operations. pub fn quantum_ops(&self) -> Result, PecosError> { + let mut commands = Vec::new(); + self.quantum_ops_into(&mut commands)?; + Ok(commands) + } + + /// Parse quantum operations from this message into an existing vector. + /// + /// This lets hot callers reuse vector capacity across repeated parses. + /// + /// # Errors + /// + /// Returns an error if the message is malformed or contains invalid quantum operations. + pub fn quantum_ops_into(&self, commands: &mut Vec) -> Result<(), PecosError> { // Parse and validate the batch header let batch_header = self.parse_batch_header()?; + let trace_enabled = log::log_enabled!(Level::Trace); - trace!( - "quantum_ops: Processing {} messages", - batch_header.msg_count - ); + if trace_enabled { + trace!( + "quantum_ops: Processing {} messages", + batch_header.msg_count + ); + } - let mut commands = Vec::new(); + commands.clear(); + commands.reserve(batch_header.msg_count as usize); let mut offset = size_of::(); // Process each message @@ -424,16 +456,20 @@ impl ByteMessage { // Add any gate we found to our commands list if let Some(gate) = maybe_gate { - trace!("quantum_ops: Message {msg_idx} parsed as gate: {gate:?}"); + if trace_enabled { + trace!("quantum_ops: Message {msg_idx} parsed as gate: {gate:?}"); + } commands.push(gate); - } else { + } else if trace_enabled { trace!("quantum_ops: Message {msg_idx} did not yield a gate"); } } - trace!("quantum_ops: Total gates parsed: {}", commands.len()); + if trace_enabled { + trace!("quantum_ops: Total gates parsed: {}", commands.len()); + } - Ok(commands) + Ok(()) } /// Parse measurement outcomes from this message @@ -498,6 +534,7 @@ impl ByteMessage { &self, offset: usize, ) -> Result<(usize, Option), PecosError> { + let trace_enabled = log::log_enabled!(Level::Trace); // Parse message header let Ok((msg_header, new_offset)) = self.parse_message_header(offset) else { // If we can't parse the header, just return the current offset with no value @@ -508,7 +545,9 @@ impl ByteMessage { // Get message type let Ok(msg_type) = msg_header.get_type() else { // Skip invalid message types - trace!("Skipping message with invalid type"); + if trace_enabled { + trace!("Skipping message with invalid type"); + } // Calculate the new offset after this message let payload_size = msg_header.payload_size as usize; @@ -582,12 +621,8 @@ impl ByteMessage { } /// Parse qubit indices from the payload and convert to `QubitIds` directly - fn parse_qubit_indices( - payload: &[u8], - qubits_offset: usize, - num_qubits: usize, - ) -> Vec { - let mut qubits = Vec::with_capacity(num_qubits); + fn parse_qubit_indices(payload: &[u8], qubits_offset: usize, num_qubits: usize) -> GateQubits { + let mut qubits = GateQubits::with_capacity(num_qubits); for i in 0..num_qubits { let qubit_offset = qubits_offset + i * size_of::(); let qubit = u32::from_le_bytes([ @@ -606,43 +641,48 @@ impl ByteMessage { payload: &[u8], params_offset: usize, gate_type: GateType, - ) -> Result, PecosError> { + ) -> Result<(GateAngles, GateParams), PecosError> { + let trace_enabled = log::log_enabled!(Level::Trace); // Get the number of parameters this gate type requires let param_count = gate_type.classical_arity(); if param_count == 0 { - return Ok(Vec::new()); + return Ok((GateAngles::new(), GateParams::new())); } - trace!("parse_gate_parameters: Gate {gate_type:?} requires {param_count} parameters"); + if trace_enabled { + trace!("parse_gate_parameters: Gate {gate_type:?} requires {param_count} parameters"); + } // Validate the parameter size let required_size = param_count * size_of::(); - Self::validate_params_size( - payload, - params_offset, - required_size, - &format!("{gate_type:?} parameters"), - )?; - - // Parse all parameters - let mut params = Vec::with_capacity(param_count); + Self::validate_params_size(payload, params_offset, required_size, gate_type)?; + + let angle_count = gate_type.angle_arity(); + let mut angles = GateAngles::with_capacity(angle_count); + let mut params = GateParams::with_capacity(param_count.saturating_sub(angle_count)); for i in 0..param_count { let param_offset = params_offset + i * size_of::(); let param = Self::parse_f64_param(payload, param_offset); - trace!("parse_gate_parameters: Parameter {i} at offset {param_offset}: {param}"); - params.push(param); + if trace_enabled { + trace!("parse_gate_parameters: Parameter {i} at offset {param_offset}: {param}"); + } + if i < angle_count { + angles.push(Angle64::from_radians(param)); + } else { + params.push(param); + } } // Special logging for RZ gate parameters - if matches!(gate_type, GateType::RZ) && !params.is_empty() { + if trace_enabled && matches!(gate_type, GateType::RZ) && !angles.is_empty() { trace!( "parse_gate_parameters: RZ angle parsed as {} radians ({} degrees)", - params[0], - params[0].to_degrees() + angles[0].to_radians(), + angles[0].to_radians().to_degrees() ); } - Ok(params) + Ok((angles, params)) } /// Validate if the payload has enough bytes for parameters @@ -650,11 +690,11 @@ impl ByteMessage { payload: &[u8], params_offset: usize, required_size: usize, - gate_name: &str, + gate_type: GateType, ) -> Result<(), PecosError> { if payload.len() < params_offset + required_size { return Err(PecosError::Input(format!( - "Quantum gate message payload too small for {gate_name}" + "Quantum gate message payload too small for {gate_type:?} parameters" ))); } Ok(()) @@ -674,6 +714,7 @@ impl ByteMessage { /// Parse a quantum gate message payload to `Gate` fn parse_gate_command(payload: &[u8]) -> Result { + let trace_enabled = log::log_enabled!(Level::Trace); Self::validate_gate_payload_size(payload)?; // Parse gate header - guaranteed aligned since payload starts at aligned boundary @@ -682,9 +723,11 @@ impl ByteMessage { let has_params = header.has_params != 0; let gate_type = GateType::from(header.gate_type); - trace!( - "parse_gate_command: Parsing gate type {gate_type:?}, num_qubits: {num_qubits}, has_params: {has_params}" - ); + if trace_enabled { + trace!( + "parse_gate_command: Parsing gate type {gate_type:?}, num_qubits: {num_qubits}, has_params: {has_params}" + ); + } // Calculate sizes let qubits_byte_size = num_qubits * size_of::(); @@ -695,31 +738,28 @@ impl ByteMessage { // Parse qubit indices directly to QubitId let qubits = Self::parse_qubit_indices(payload, qubits_offset, num_qubits); - trace!("parse_gate_command: Parsed qubits: {qubits:?}"); + if trace_enabled { + trace!("parse_gate_command: Parsed qubits: {qubits:?}"); + } // Parse parameters if present // The wire format stores all classical parameters as f64, with angles first (in radians) let (angles, params) = if has_params { let params_offset = qubits_offset + qubits_byte_size; - let parsed_params = Self::parse_gate_parameters(payload, params_offset, gate_type)?; - trace!("parse_gate_command: Parsed parameters: {parsed_params:?}"); - - // Split into angles and other params based on gate type - let angle_count = gate_type.angle_arity(); - let angles: Vec = parsed_params - .iter() - .take(angle_count) - .map(|&r| Angle64::from_radians(r)) - .collect(); - let other_params: Vec = parsed_params.into_iter().skip(angle_count).collect(); - - (angles, other_params) + let parsed = Self::parse_gate_parameters(payload, params_offset, gate_type)?; + if trace_enabled { + trace!( + "parse_gate_command: Parsed parameters: angles={:?}, params={:?}", + parsed.0, parsed.1 + ); + } + parsed } else { - (Vec::new(), Vec::new()) + (GateAngles::new(), GateParams::new()) }; // Special logging for RZ gates - if matches!(gate_type, GateType::RZ) { + if trace_enabled && matches!(gate_type, GateType::RZ) { trace!( "parse_gate_command: RZ gate parsed with angle: {:?}, qubit: {:?}", angles.first(), diff --git a/crates/pecos-engines/src/lib.rs b/crates/pecos-engines/src/lib.rs index 156e8fe83..e24ac46ce 100644 --- a/crates/pecos-engines/src/lib.rs +++ b/crates/pecos-engines/src/lib.rs @@ -30,14 +30,14 @@ pub use noise::{ }; pub use pecos_core::errors::PecosError; pub use quantum::{ - CliffordRzEngine, CoinTossEngine, DenseStateVecEngine, DensityMatrixEngine, QuantumEngine, + CoinTossEngine, DenseStateVecEngine, DensityMatrixEngine, QuantumEngine, StabVecEngine, StabilizerEngine, StateVecEngine, StateVectorEngine, StateVectorSimulator, }; pub use quantum_engine_builder::{ - CliffordRzEngineBuilder, CoinTossEngineBuilder, DensityMatrixEngineBuilder, - IntoQuantumEngineBuilder, QuantumEngineBuilder, SparseStabEngineBuilder, - StabilizerEngineBuilder, StateVectorEngineBuilder, clifford_rz, coin_toss, density_matrix, - sparse_stab, stabilizer, state_vector, + CoinTossEngineBuilder, DensityMatrixEngineBuilder, IntoQuantumEngineBuilder, + QuantumEngineBuilder, SparseStabEngineBuilder, StabVecEngineBuilder, StabilizerEngineBuilder, + StateVectorEngineBuilder, coin_toss, density_matrix, sparse_stab, stab_vec, stabilizer, + state_vector, }; pub use quantum_system::QuantumSystem; pub use shot_results::data_vec::DataVecType; diff --git a/crates/pecos-engines/src/noise/biased_depolarizing.rs b/crates/pecos-engines/src/noise/biased_depolarizing.rs index 47d992f12..db3f4ab2a 100644 --- a/crates/pecos-engines/src/noise/biased_depolarizing.rs +++ b/crates/pecos-engines/src/noise/biased_depolarizing.rs @@ -222,7 +222,8 @@ impl BiasedDepolarizingNoiseModel { | GateType::MeasCrosstalkLocalPayload | GateType::MeasCrosstalkGlobalPayload | GateType::QFree - | GateType::Custom => {} + | GateType::Custom + | GateType::PauliOperatorMeta => {} } } diff --git a/crates/pecos-engines/src/noise/depolarizing.rs b/crates/pecos-engines/src/noise/depolarizing.rs index fdfe4e0cf..cb2f88e2f 100644 --- a/crates/pecos-engines/src/noise/depolarizing.rs +++ b/crates/pecos-engines/src/noise/depolarizing.rs @@ -72,6 +72,10 @@ pub struct DepolarizingNoiseModel { p2_threshold: u64, /// Random number generator rng: NoiseRng, + /// Scratch builder reused across batches to avoid repeated allocations. + scratch_builder: ByteMessageBuilder, + /// Scratch gate storage reused across batches to avoid repeated allocations. + scratch_gates: Vec, } impl ProbabilityValidator for DepolarizingNoiseModel {} @@ -111,6 +115,8 @@ impl DepolarizingNoiseModel { p1_threshold: Self::compute_threshold(p1), p2_threshold: Self::compute_threshold(p2), rng: NoiseRng::default(), + scratch_builder: NoiseUtils::create_quantum_builder(), + scratch_gates: Vec::new(), } } @@ -156,114 +162,121 @@ impl DepolarizingNoiseModel { (self.p_prep, self.p_meas, self.p1, self.p2) } - /// Apply noise to a list of quantum gates - fn apply_noise_to_gates(&mut self, gates: &[Gate]) -> ByteMessage { - let mut builder = NoiseUtils::create_quantum_builder(); - - for gate in gates { - match gate.gate_type { - GateType::X - | GateType::Z - | GateType::Y - | GateType::SX - | GateType::SXdg - | GateType::SY - | GateType::SYdg - | GateType::SZ - | GateType::SZdg - | GateType::H - | GateType::F - | GateType::Fdg - | GateType::RX - | GateType::RY - | GateType::RZ - | GateType::T - | GateType::Tdg - | GateType::U - | GateType::R1XY => { - NoiseUtils::add_gate_to_builder(&mut builder, gate); - trace!("Applying single-qubit gate with possible fault"); - self.apply_sq_faults(&mut builder, gate); - } - GateType::CX - | GateType::CY - | GateType::CZ - | GateType::CH - | GateType::SXX - | GateType::SXXdg - | GateType::SYY - | GateType::SYYdg - | GateType::SZZ - | GateType::SZZdg - | GateType::SWAP - | GateType::CRZ - | GateType::RXX - | GateType::RYY - | GateType::RZZ - | GateType::RXXRYYRZZ - | GateType::U2q => { - NoiseUtils::add_gate_to_builder(&mut builder, gate); - trace!("Applying two-qubit gate with possible fault"); - self.apply_tq_faults(&mut builder, gate); - } - GateType::CCX => { - NoiseUtils::add_gate_to_builder(&mut builder, gate); - trace!("Applying three-qubit gate with possible fault"); - // Apply fault to each qubit pair - self.apply_tq_faults(&mut builder, gate); - } - GateType::MZ | GateType::MeasureLeaked | GateType::MeasureFree => { - trace!("Applying measurement with possible fault"); - self.apply_meas_faults(&mut builder, gate); - NoiseUtils::add_gate_to_builder(&mut builder, gate); - } - GateType::PZ | GateType::QAlloc => { - NoiseUtils::add_gate_to_builder(&mut builder, gate); - trace!("Applying preparation with possible fault"); - self.apply_prep_faults(&mut builder, gate); - } - GateType::I - | GateType::Idle - | GateType::MeasCrosstalkLocalPayload - | GateType::MeasCrosstalkGlobalPayload - | GateType::QFree - | GateType::Custom => { - // Just pass through with no added noise - // QFree has no physical operation to apply noise to - } + fn apply_noise_to_gate( + rng: &mut NoiseRng, + p_prep_threshold: u64, + p_meas_threshold: u64, + p1_threshold: u64, + p2_threshold: u64, + builder: &mut ByteMessageBuilder, + gate: &Gate, + ) { + match gate.gate_type { + GateType::X + | GateType::Z + | GateType::Y + | GateType::SX + | GateType::SXdg + | GateType::SY + | GateType::SYdg + | GateType::SZ + | GateType::SZdg + | GateType::H + | GateType::F + | GateType::Fdg + | GateType::RX + | GateType::RY + | GateType::RZ + | GateType::T + | GateType::Tdg + | GateType::U + | GateType::R1XY => { + NoiseUtils::add_gate_to_builder(builder, gate); + trace!("Applying single-qubit gate with possible fault"); + Self::apply_sq_faults(rng, p1_threshold, builder, gate); + } + GateType::CX + | GateType::CY + | GateType::CZ + | GateType::CH + | GateType::SXX + | GateType::SXXdg + | GateType::SYY + | GateType::SYYdg + | GateType::SZZ + | GateType::SZZdg + | GateType::SWAP + | GateType::CRZ + | GateType::RXX + | GateType::RYY + | GateType::RZZ + | GateType::RXXRYYRZZ + | GateType::U2q => { + NoiseUtils::add_gate_to_builder(builder, gate); + trace!("Applying two-qubit gate with possible fault"); + Self::apply_tq_faults(rng, p2_threshold, builder, gate); + } + GateType::CCX => { + NoiseUtils::add_gate_to_builder(builder, gate); + trace!("Applying three-qubit gate with possible fault"); + Self::apply_tq_faults(rng, p2_threshold, builder, gate); + } + GateType::MZ | GateType::MeasureLeaked | GateType::MeasureFree => { + trace!("Applying measurement with possible fault"); + Self::apply_meas_faults(rng, p_meas_threshold, builder, gate); + NoiseUtils::add_gate_to_builder(builder, gate); + } + GateType::PZ | GateType::QAlloc => { + NoiseUtils::add_gate_to_builder(builder, gate); + trace!("Applying preparation with possible fault"); + Self::apply_prep_faults(rng, p_prep_threshold, builder, gate); + } + GateType::I + | GateType::Idle + | GateType::MeasCrosstalkLocalPayload + | GateType::MeasCrosstalkGlobalPayload + | GateType::QFree + | GateType::Custom + | GateType::PauliOperatorMeta => { + // Just pass through with no added noise. } } - - builder.build() } - fn apply_prep_faults(&mut self, builder: &mut ByteMessageBuilder, gate: &Gate) { + fn apply_prep_faults( + rng: &mut NoiseRng, + p_prep_threshold: u64, + builder: &mut ByteMessageBuilder, + gate: &Gate, + ) { // Use precomputed threshold for fast probability check - if self - .rng - .inner_mut() - .check_probability(self.p_prep_threshold) - { + if rng.inner_mut().check_probability(p_prep_threshold) { trace!("Applying prep fault on qubits {:?}", gate.qubits); NoiseUtils::apply_x(builder, *gate.qubits[0]); } } - fn apply_meas_faults(&mut self, builder: &mut ByteMessageBuilder, gate: &Gate) { + fn apply_meas_faults( + rng: &mut NoiseRng, + p_meas_threshold: u64, + builder: &mut ByteMessageBuilder, + gate: &Gate, + ) { // Use precomputed threshold for fast probability check - if self - .rng - .inner_mut() - .check_probability(self.p_meas_threshold) - { + if rng.inner_mut().check_probability(p_meas_threshold) { trace!("Applying meas fault on qubits {:?}", gate.qubits); NoiseUtils::apply_x(builder, *gate.qubits[0]); } } - fn apply_sq_faults(&mut self, builder: &mut ByteMessageBuilder, gate: &Gate) { + fn apply_sq_faults( + rng: &mut NoiseRng, + p1_threshold: u64, + builder: &mut ByteMessageBuilder, + gate: &Gate, + ) { // Use fused noise sampling: probability check + Pauli selection in one call - if let Some(fault_type) = self.rng.inner_mut().noise_sample_1q(self.p1_threshold) { + if let Some(fault_type) = rng.inner_mut().noise_sample_1q(p1_threshold) { let qubit = gate.qubits[0]; match fault_type { @@ -283,9 +296,14 @@ impl DepolarizingNoiseModel { } } - fn apply_tq_faults(&mut self, builder: &mut ByteMessageBuilder, gate: &Gate) { + fn apply_tq_faults( + rng: &mut NoiseRng, + p2_threshold: u64, + builder: &mut ByteMessageBuilder, + gate: &Gate, + ) { // Use fused noise sampling: probability check + Pauli selection in one call - if let Some(fault_type) = self.rng.inner_mut().noise_sample_2q(self.p2_threshold) { + if let Some(fault_type) = rng.inner_mut().noise_sample_2q(p2_threshold) { let qubit0 = gate.qubits[0]; let qubit1 = gate.qubits[1]; @@ -546,13 +564,42 @@ impl ControlEngine for DepolarizingNoiseModel { // For quantum operations, apply gate noise trace!("DepolarizingNoise::start - applying noise to quantum operations"); - // Parse the input as quantum operations - let gates: Vec = input - .quantum_ops() + if self.p_prep_threshold == 0 + && self.p_meas_threshold == 0 + && self.p1_threshold == 0 + && self.p2_threshold == 0 + { + return Ok(EngineStage::NeedsProcessing(input)); + } + + self.scratch_gates.clear(); + input + .quantum_ops_into(&mut self.scratch_gates) .map_err(|e| PecosError::Input(format!("Failed to parse quantum operations: {e}")))?; - // Apply noise to the gates - let noisy_gates = self.apply_noise_to_gates(&gates); + self.scratch_builder.reset(); + let _ = self.scratch_builder.for_quantum_operations(); + + let p_prep_threshold = self.p_prep_threshold; + let p_meas_threshold = self.p_meas_threshold; + let p1_threshold = self.p1_threshold; + let p2_threshold = self.p2_threshold; + let rng = &mut self.rng; + let builder = &mut self.scratch_builder; + + for gate in &self.scratch_gates { + Self::apply_noise_to_gate( + rng, + p_prep_threshold, + p_meas_threshold, + p1_threshold, + p2_threshold, + builder, + gate, + ); + } + + let noisy_gates = self.scratch_builder.build(); // Return the noisy operations Ok(EngineStage::NeedsProcessing(noisy_gates)) diff --git a/crates/pecos-engines/src/noise/utils.rs b/crates/pecos-engines/src/noise/utils.rs index c22a564a5..606f0338a 100644 --- a/crates/pecos-engines/src/noise/utils.rs +++ b/crates/pecos-engines/src/noise/utils.rs @@ -171,93 +171,13 @@ impl NoiseUtils { /// - `gate` is `None` when processing a measurement gate /// - The gate type is invalid or has insufficient parameters/qubits for the operation pub fn add_gate_to_builder(builder: &mut ByteMessageBuilder, gate: &Gate) { - use crate::byte_message::GateType; - - match gate.gate_type { - // Single-qubit gates that operate directly on qubit lists - GateType::X => { - let qubits_usize: Vec = gate.qubits.iter().map(|q| **q).collect(); - builder.x(&qubits_usize); - } - GateType::Y => { - let qubits_usize: Vec = gate.qubits.iter().map(|q| **q).collect(); - builder.y(&qubits_usize); - } - GateType::Z => { - let qubits_usize: Vec = gate.qubits.iter().map(|q| **q).collect(); - builder.z(&qubits_usize); - } - GateType::H => { - let qubits_usize: Vec = gate.qubits.iter().map(|q| **q).collect(); - builder.h(&qubits_usize); - } - GateType::PZ => { - let qubits_usize: Vec = gate.qubits.iter().map(|q| **q).collect(); - builder.pz(&qubits_usize); - } - - // Two-qubit gates that need qubit validation - GateType::CX if gate.qubits.len() >= 2 => { - builder.cx(&[(*gate.qubits[0], *gate.qubits[1])]); - } - GateType::SZZ if gate.qubits.len() >= 2 => { - builder.szz(&[(*gate.qubits[0], *gate.qubits[1])]); - } - GateType::SZZdg if gate.qubits.len() >= 2 => { - builder.szzdg(&[(*gate.qubits[0], *gate.qubits[1])]); - } - - // Rotation gates - angles are now stored in gate.angles field - GateType::RX if !gate.angles.is_empty() => { - let qubits_usize: Vec = gate.qubits.iter().map(|q| **q).collect(); - builder.rx(gate.angles[0], &qubits_usize); - } - GateType::RY if !gate.angles.is_empty() => { - let qubits_usize: Vec = gate.qubits.iter().map(|q| **q).collect(); - builder.ry(gate.angles[0], &qubits_usize); - } - GateType::RZ if !gate.angles.is_empty() => { - let qubits_usize: Vec = gate.qubits.iter().map(|q| **q).collect(); - builder.rz(gate.angles[0], &qubits_usize); - } - GateType::RZZ if gate.qubits.len() >= 2 && !gate.angles.is_empty() => { - builder.rzz(gate.angles[0], &[(*gate.qubits[0], *gate.qubits[1])]); - } - GateType::R1XY if gate.angles.len() >= 2 => { - let qubits_usize: Vec = gate.qubits.iter().map(|q| **q).collect(); - builder.r1xy(gate.angles[0], gate.angles[1], &qubits_usize); - } - GateType::U if gate.angles.len() >= 3 => { - let qubits_usize: Vec = gate.qubits.iter().map(|q| **q).collect(); - builder.u( - gate.angles[0], - gate.angles[1], - gate.angles[2], - &qubits_usize, - ); - } - - // Measurement gates - GateType::MZ if !gate.qubits.is_empty() => { - let qubits_usize: Vec = gate.qubits.iter().map(|q| **q).collect(); - builder.mz(&qubits_usize); - } - - // Idle gates need special handling for qubit lists - GateType::Idle if !gate.params.is_empty() => { - // Use gate params for idle time - let qubits_usize: Vec = gate.qubits.iter().map(|q| **q).collect(); - builder.idle(gate.params[0], &qubits_usize); - } - - // Custom is a placeholder (actual gate name is in metadata) -- skip. - GateType::Custom => {} - - // All other gates: use generic serialization (gate type + qubits + angles/params). - _ => { - builder.add_gate_command(gate); - } + if gate.gate_type == crate::byte_message::GateType::Custom { + return; } + + // Generic serialization is cheaper here because it reuses the parsed gate directly + // instead of rebuilding temporary qubit vectors first. + builder.add_gate_command(gate); } /// Check if a message contains measurement results diff --git a/crates/pecos-engines/src/prelude.rs b/crates/pecos-engines/src/prelude.rs index 1bae72a9c..f30bd3557 100644 --- a/crates/pecos-engines/src/prelude.rs +++ b/crates/pecos-engines/src/prelude.rs @@ -21,13 +21,13 @@ pub use crate::{ // Quantum engines and builders pub use crate::quantum::{ - CliffordRzEngine, CoinTossEngine, DensityMatrixEngine, QuantumEngine, SparseStabEngine, + CoinTossEngine, DensityMatrixEngine, QuantumEngine, SparseStabEngine, StabVecEngine, StabilizerEngine, StateVecEngine, new_quantum_engine_arbitrary_qgate, }; pub use crate::quantum_engine_builder::{ - CliffordRzEngineBuilder, CoinTossEngineBuilder, DensityMatrixEngineBuilder, - IntoQuantumEngineBuilder, SparseStabEngineBuilder, StabilizerEngineBuilder, - StateVectorEngineBuilder, clifford_rz, coin_toss, density_matrix, sparse_stab, stabilizer, + CoinTossEngineBuilder, DensityMatrixEngineBuilder, IntoQuantumEngineBuilder, + SparseStabEngineBuilder, StabVecEngineBuilder, StabilizerEngineBuilder, + StateVectorEngineBuilder, coin_toss, density_matrix, sparse_stab, stab_vec, stabilizer, state_vector, }; diff --git a/crates/pecos-engines/src/quantum.rs b/crates/pecos-engines/src/quantum.rs index c702330a6..c4aa06c15 100644 --- a/crates/pecos-engines/src/quantum.rs +++ b/crates/pecos-engines/src/quantum.rs @@ -10,8 +10,8 @@ use pecos_core::errors::PecosError; use pecos_random::{PecosRng, SeedableRng}; use pecos_simulators::clifford_rotation::CliffordRotation; use pecos_simulators::{ - ArbitraryRotationGateable, CliffordGateable, CliffordRz, CoinToss, DensityMatrix, - QuantumSimulator, SparseStab, Stabilizer, StateVec, StateVecAoS, StateVecSoA, + ArbitraryRotationGateable, CliffordGateable, CoinToss, DensityMatrix, QuantumSimulator, + SparseStab, StabVec, Stabilizer, StateVec, StateVecAoS, StateVecSoA, }; use std::any::Any; use std::fmt::Debug; @@ -21,12 +21,37 @@ fn quantum_error>(msg: S) -> PecosError { PecosError::Processing(msg.into()) } +/// Apply a closure to a flat qubit slice `[c0, t0, c1, t1, ...]` and return its result. +/// +/// Most commands contain a single pair, so avoid heap allocation in that case +/// and reuse a scratch buffer for the rarer batched-pair path. The closure's +/// return value is forwarded so fallible gates (e.g. `try_rzz`) can bubble up +/// a `Result` without a separate borrow-and-stash dance at the call site. +fn with_flat_pairs( + qubits: &[QubitId], + pair_scratch: &mut Vec<(QubitId, QubitId)>, + mut f: F, +) -> R +where + F: FnMut(&[(QubitId, QubitId)]) -> R, +{ + debug_assert_eq!(qubits.len() % 2, 0); + + if qubits.len() == 2 { + let pair = [(qubits[0], qubits[1])]; + return f(&pair); + } + + pair_scratch.clear(); + pair_scratch.extend(qubits.chunks_exact(2).map(|pair| (pair[0], pair[1]))); + f(pair_scratch) +} + /// Convert a flat qubit slice `[c0, t0, c1, t1, ...]` to a vec of pairs. fn flat_to_pairs(qubits: &[QubitId]) -> Vec<(QubitId, QubitId)> { - qubits - .chunks_exact(2) - .map(|pair| (pair[0], pair[1])) - .collect() + let mut pairs = Vec::with_capacity(qubits.len() / 2); + pairs.extend(qubits.chunks_exact(2).map(|pair| (pair[0], pair[1]))); + pairs } /// Process a `ByteMessage` against any Clifford-capable simulator. @@ -40,6 +65,8 @@ fn process_clifford_message Result { let batch = message.quantum_ops()?; let mut measurements: Vec = Vec::new(); + let mut pair_scratch: Vec<(QubitId, QubitId)> = Vec::new(); + let mut mz_qubits: Vec = Vec::new(); let mut cmd_idx = 0; while cmd_idx < batch.len() { @@ -79,39 +106,60 @@ fn process_clifford_message { - sim.cx(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.cx(pairs); + }); } GateType::CY => { - sim.cy(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.cy(pairs); + }); } GateType::CZ => { - sim.cz(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.cz(pairs); + }); } GateType::SWAP => { - sim.swap(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.swap(pairs); + }); } GateType::SZZ => { - sim.szz(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.szz(pairs); + }); } GateType::SZZdg => { - sim.szzdg(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.szzdg(pairs); + }); } GateType::SXX => { - sim.sxx(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.sxx(pairs); + }); } GateType::SXXdg => { - sim.sxxdg(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.sxxdg(pairs); + }); } GateType::SYY => { - sim.syy(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.syy(pairs); + }); } GateType::SYYdg => { - sim.syydg(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.syydg(pairs); + }); } // Batch consecutive MZ commands GateType::MZ | GateType::MeasureLeaked => { - let mut mz_qubits: Vec = cmd.qubits.to_vec(); + mz_qubits.clear(); + mz_qubits.extend_from_slice(&cmd.qubits); while cmd_idx + 1 < batch.len() && matches!( batch[cmd_idx + 1].gate_type, @@ -121,9 +169,9 @@ fn process_clifford_message { if !cmd.angles.is_empty() { let angle = cmd.angles[0]; - let result = match cmd.gate_type { - GateType::RZ => sim.try_rz(angle, &cmd.qubits), - GateType::RX => sim.try_rx(angle, &cmd.qubits), - GateType::RY => sim.try_ry(angle, &cmd.qubits), - GateType::RZZ => sim.try_rzz(angle, &flat_to_pairs(&cmd.qubits)), - GateType::RXX => sim.try_rxx(angle, &flat_to_pairs(&cmd.qubits)), - GateType::RYY => sim.try_ryy(angle, &flat_to_pairs(&cmd.qubits)), + let result: Result<(), String> = match cmd.gate_type { + GateType::RZ => sim.try_rz(angle, &cmd.qubits).map(|_| ()), + GateType::RX => sim.try_rx(angle, &cmd.qubits).map(|_| ()), + GateType::RY => sim.try_ry(angle, &cmd.qubits).map(|_| ()), + GateType::RZZ => with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.try_rzz(angle, pairs).map(|_| ()) + }), + GateType::RXX => with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.try_rxx(angle, pairs).map(|_| ()) + }), + GateType::RYY => with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.try_ryy(angle, pairs).map(|_| ()) + }), _ => unreachable!(), }; result.map_err(PecosError::Processing)?; @@ -161,8 +215,10 @@ fn process_clifford_message { if !cmd.angles.is_empty() { - sim.try_crz(cmd.angles[0], &flat_to_pairs(&cmd.qubits)) - .map_err(PecosError::Processing)?; + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.try_crz(cmd.angles[0], pairs).map(|_| ()) + }) + .map_err(PecosError::Processing)?; } } GateType::U => { @@ -173,12 +229,10 @@ fn process_clifford_message { if cmd.angles.len() >= 3 { - sim.try_rxxryyrzz( - cmd.angles[0], - cmd.angles[1], - cmd.angles[2], - &flat_to_pairs(&cmd.qubits), - ) + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.try_rxxryyrzz(cmd.angles[0], cmd.angles[1], cmd.angles[2], pairs) + .map(|_| ()) + }) .map_err(PecosError::Processing)?; } } @@ -193,8 +247,10 @@ fn process_clifford_message( @@ -224,6 +280,8 @@ fn process_general_message Result { let batch = message.quantum_ops()?; let mut measurements: Vec = Vec::new(); + let mut pair_scratch: Vec<(QubitId, QubitId)> = Vec::new(); + let mut mz_qubits: Vec = Vec::new(); let mut cmd_idx = 0; while cmd_idx < batch.len() { @@ -277,34 +335,54 @@ fn process_general_message { - sim.cx(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.cx(pairs); + }); } GateType::CY => { - sim.cy(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.cy(pairs); + }); } GateType::CZ => { - sim.cz(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.cz(pairs); + }); } GateType::SZZ => { - sim.szz(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.szz(pairs); + }); } GateType::SZZdg => { - sim.szzdg(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.szzdg(pairs); + }); } GateType::SXX => { - sim.sxx(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.sxx(pairs); + }); } GateType::SXXdg => { - sim.sxxdg(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.sxxdg(pairs); + }); } GateType::SYY => { - sim.syy(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.syy(pairs); + }); } GateType::SYYdg => { - sim.syydg(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.syydg(pairs); + }); } GateType::SWAP => { - sim.swap(&flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.swap(pairs); + }); } // Composite gates (decomposed into primitives) @@ -363,17 +441,23 @@ fn process_general_message { if !cmd.angles.is_empty() { - sim.rzz(cmd.angles[0], &flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.rzz(cmd.angles[0], pairs); + }); } } GateType::RXX => { if !cmd.angles.is_empty() { - sim.rxx(cmd.angles[0], &flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.rxx(cmd.angles[0], pairs); + }); } } GateType::RYY => { if !cmd.angles.is_empty() { - sim.ryy(cmd.angles[0], &flat_to_pairs(&cmd.qubits)); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.ryy(cmd.angles[0], pairs); + }); } } GateType::CRZ => { @@ -400,12 +484,9 @@ fn process_general_message { if cmd.angles.len() >= 3 { - sim.rxxryyrzz( - cmd.angles[0], - cmd.angles[1], - cmd.angles[2], - &flat_to_pairs(&cmd.qubits), - ); + with_flat_pairs(&cmd.qubits, &mut pair_scratch, |pairs| { + sim.rxxryyrzz(cmd.angles[0], cmd.angles[1], cmd.angles[2], pairs); + }); } } GateType::U2q => { @@ -419,13 +500,16 @@ fn process_general_message { - let mut mz_qubits: Vec = cmd.qubits.to_vec(); + mz_qubits.clear(); + mz_qubits.extend_from_slice(&cmd.qubits); while cmd_idx + 1 < batch.len() && matches!( batch[cmd_idx + 1].gate_type, @@ -435,15 +519,15 @@ fn process_general_message { - let meas_results = sim.mz(&cmd.qubits); - for meas_result in meas_results { - measurements.push(usize::from(meas_result.outcome)); + let meas_ids = sim.mz(&cmd.qubits); + for meas_id in meas_ids { + measurements.push(usize::from(meas_id.outcome)); } } @@ -458,7 +542,8 @@ fn process_general_message {} + | GateType::Custom + | GateType::PauliOperatorMeta => {} } cmd_idx += 1; } @@ -517,9 +602,6 @@ pub trait StateVectorSimulator: where ::Rng: Clone, { - /// Returns the number of qubits in the simulator. - fn num_qubits(&self) -> usize; - /// Create a new simulator with the specified number of qubits. fn create(num_qubits: usize) -> Self; @@ -531,10 +613,6 @@ where } impl StateVectorSimulator for StateVec { - fn num_qubits(&self) -> usize { - self.num_qubits() - } - fn create(num_qubits: usize) -> Self { StateVec::new(num_qubits) } @@ -549,10 +627,6 @@ impl StateVectorSimulator for StateVec { } impl StateVectorSimulator for StateVecAoS { - fn num_qubits(&self) -> usize { - self.num_qubits() - } - fn create(num_qubits: usize) -> Self { StateVecAoS::new(num_qubits) } @@ -567,10 +641,6 @@ impl StateVectorSimulator for StateVecAoS { } impl StateVectorSimulator for StateVecSoA { - fn num_qubits(&self) -> usize { - self.num_qubits() - } - fn create(num_qubits: usize) -> Self { StateVecSoA::new(num_qubits) } @@ -1015,9 +1085,9 @@ where "Processing batched measurement on {} qubits", mz_qubits.len() ); - let meas_results = self.simulator.mz(&mz_qubits); - for meas_result in meas_results { - measurements.push(usize::from(meas_result.outcome)); + let meas_ids = self.simulator.mz(&mz_qubits); + for meas_id in meas_ids { + measurements.push(usize::from(meas_id.outcome)); } } GateType::PZ => { @@ -1029,7 +1099,8 @@ where | GateType::MeasCrosstalkLocalPayload | GateType::MeasCrosstalkGlobalPayload | GateType::QFree - | GateType::Custom => { + | GateType::Custom + | GateType::PauliOperatorMeta => { // Just let the system naturally evolve for the specified duration // No active operation needed in the simulator // QFree is a no-op for state vector simulation (qubit tracking is handled elsewhere) @@ -1073,9 +1144,9 @@ where GateType::MeasureFree => { // Measure and deallocate - measure first, then the qubit is implicitly freed debug!("Processing MeasureFree gate on qubits {:?}", cmd.qubits); - let meas_results = self.simulator.mz(&cmd.qubits); - for meas_result in meas_results { - measurements.push(usize::from(meas_result.outcome)); + let meas_ids = self.simulator.mz(&cmd.qubits); + for meas_id in meas_ids { + measurements.push(usize::from(meas_id.outcome)); } } GateType::U => { @@ -1350,25 +1421,25 @@ impl QuantumEngine for StabilizerEngine { } // ============================================================================ -// Clifford+RZ Engine +// StabVec Engine // ============================================================================ -/// A quantum engine that uses the Clifford+RZ simulator. +/// A quantum engine that uses the `StabVec` simulator. /// /// Supports all Clifford gates plus arbitrary rotation gates (RZ, RX, RY, RZZ, etc.) /// via sum-over-Cliffords decomposition. More efficient than state vector for /// circuits with many qubits and few non-Clifford gates. #[derive(Debug, Clone)] -pub struct CliffordRzEngine { - simulator: CliffordRz, +pub struct StabVecEngine { + simulator: StabVec, } -impl CliffordRzEngine { - /// Create a new Clifford+RZ engine with the specified number of qubits. +impl StabVecEngine { + /// Create a new `StabVec` engine with the specified number of qubits. #[must_use] pub fn new(num_qubits: usize) -> Self { Self { - simulator: CliffordRz::new(num_qubits), + simulator: StabVec::new(num_qubits), } } @@ -1376,12 +1447,12 @@ impl CliffordRzEngine { #[must_use] pub fn with_seed(num_qubits: usize, seed: u64) -> Self { Self { - simulator: CliffordRz::new_with_seed(num_qubits, seed), + simulator: StabVec::new_with_seed(num_qubits, seed), } } } -impl Engine for CliffordRzEngine { +impl Engine for StabVecEngine { type Input = ByteMessage; type Output = ByteMessage; @@ -1395,7 +1466,7 @@ impl Engine for CliffordRzEngine { } } -impl RngManageable for CliffordRzEngine { +impl RngManageable for StabVecEngine { type Rng = PecosRng; fn set_rng(&mut self, rng: Self::Rng) { @@ -1411,7 +1482,7 @@ impl RngManageable for CliffordRzEngine { } } -impl QuantumEngine for CliffordRzEngine { +impl QuantumEngine for StabVecEngine { fn set_seed(&mut self, seed: u64) { let rng = PecosRng::seed_from_u64(seed); self.simulator.set_rng(rng); @@ -1560,9 +1631,9 @@ impl Engine for CoinTossEngine { GateType::MZ | GateType::MeasureLeaked | GateType::MeasureFree => { for q in &cmd.qubits { debug!("CoinToss: Processing measurement on qubit {q:?}"); - let meas_results = self.simulator.mz(&[*q]); - for meas_result in &meas_results { - let outcome = u32::from(meas_result.outcome); + let meas_ids = self.simulator.mz(&[*q]); + for meas_id in &meas_ids { + let outcome = u32::from(meas_id.outcome); measurements.push(outcome); } } diff --git a/crates/pecos-engines/src/quantum_engine_builder.rs b/crates/pecos-engines/src/quantum_engine_builder.rs index 1ae0e754a..c185acdff 100644 --- a/crates/pecos-engines/src/quantum_engine_builder.rs +++ b/crates/pecos-engines/src/quantum_engine_builder.rs @@ -339,11 +339,11 @@ pub fn stabilizer() -> StabilizerEngineBuilder { /// Builder for Clifford+RZ quantum engine #[derive(Debug, Clone, Default)] -pub struct CliffordRzEngineBuilder { +pub struct StabVecEngineBuilder { num_qubits: Option, } -impl CliffordRzEngineBuilder { +impl StabVecEngineBuilder { #[must_use] pub fn new() -> Self { Self::default() @@ -356,12 +356,12 @@ impl CliffordRzEngineBuilder { } } -impl QuantumEngineBuilder for CliffordRzEngineBuilder { +impl QuantumEngineBuilder for StabVecEngineBuilder { fn build(&mut self) -> Result, PecosError> { let num_qubits = self.num_qubits.ok_or_else(|| { PecosError::Input("Number of qubits not specified for Clifford+RZ engine".to_string()) })?; - Ok(Box::new(crate::quantum::CliffordRzEngine::new(num_qubits))) + Ok(Box::new(crate::quantum::StabVecEngine::new(num_qubits))) } fn set_qubits_if_needed(&mut self, num_qubits: usize) { @@ -371,7 +371,7 @@ impl QuantumEngineBuilder for CliffordRzEngineBuilder { } } -impl IntoQuantumEngineBuilder for CliffordRzEngineBuilder { +impl IntoQuantumEngineBuilder for StabVecEngineBuilder { type Builder = Self; fn into_quantum_engine_builder(self) -> Self::Builder { @@ -381,8 +381,8 @@ impl IntoQuantumEngineBuilder for CliffordRzEngineBuilder { /// Create a Clifford+RZ quantum engine builder #[must_use] -pub fn clifford_rz() -> CliffordRzEngineBuilder { - CliffordRzEngineBuilder::new() +pub fn stab_vec() -> StabVecEngineBuilder { + StabVecEngineBuilder::new() } /// Builder for density matrix quantum engine diff --git a/crates/pecos-engines/src/sim_builder.rs b/crates/pecos-engines/src/sim_builder.rs index fd86c5a29..a858e94ef 100644 --- a/crates/pecos-engines/src/sim_builder.rs +++ b/crates/pecos-engines/src/sim_builder.rs @@ -196,9 +196,8 @@ impl SimBuilder { /// Use automatic worker count based on available CPUs #[must_use] pub fn auto_workers(mut self) -> Self { - self.config.workers = std::thread::available_parallelism() - .map(std::num::NonZero::get) - .unwrap_or(4); + self.config.workers = + std::thread::available_parallelism().map_or(4, std::num::NonZero::get); self } diff --git a/crates/pecos-engines/tests/noise_determinism.rs b/crates/pecos-engines/tests/noise_determinism.rs index ed5069ca1..42082427c 100644 --- a/crates/pecos-engines/tests/noise_determinism.rs +++ b/crates/pecos-engines/tests/noise_determinism.rs @@ -117,7 +117,7 @@ fn compare_messages(msg1: &ByteMessage, msg2: &ByteMessage) -> bool { let results_left = msg1.outcomes().unwrap_or_default(); let results_right = msg2.outcomes().unwrap_or_default(); if quantum_ops_left != quantum_ops_right { - eprintln!("Quantum operations differ: {quantum_ops_left:?} vs {quantum_ops_right:?}",); + eprintln!("Quantum operations differ: {quantum_ops_left:?} vs {quantum_ops_right:?}"); return false; } if results_left != results_right { diff --git a/crates/pecos-engines/tests/sparse_stab_rotation_test.rs b/crates/pecos-engines/tests/sparse_stab_rotation_test.rs index 95046280f..a2326a86c 100644 --- a/crates/pecos-engines/tests/sparse_stab_rotation_test.rs +++ b/crates/pecos-engines/tests/sparse_stab_rotation_test.rs @@ -301,6 +301,28 @@ fn r1xy_negated_y_axis_acts_as_y() { assert_eq!(outcomes, vec![1]); } +#[test] +fn r1xy_quarter_turn_negated_x_axis_acts_as_sxdg() { + // R1XY(pi/2, pi) = SXdg, so SXdg * SX = I. + let outcomes = run_sparse_stab(1, |b| { + b.r1xy(Angle64::QUARTER_TURN, Angle64::HALF_TURN, &[0]); + b.r1xy(Angle64::QUARTER_TURN, Angle64::ZERO, &[0]); + b.mz(&[0]); + }); + assert_eq!(outcomes, vec![0]); +} + +#[test] +fn r1xy_quarter_turn_negated_y_axis_acts_as_sydg() { + // R1XY(pi/2, 3pi/2) = SYdg, so SYdg * SY = I. + let outcomes = run_sparse_stab(1, |b| { + b.r1xy(Angle64::QUARTER_TURN, Angle64::THREE_QUARTERS_TURN, &[0]); + b.r1xy(Angle64::QUARTER_TURN, Angle64::QUARTER_TURN, &[0]); + b.mz(&[0]); + }); + assert_eq!(outcomes, vec![0]); +} + // --- U gate tests --- #[test] diff --git a/crates/pecos-engines/tests/clifford_rz_engine_test.rs b/crates/pecos-engines/tests/stab_vec_engine_test.rs similarity index 91% rename from crates/pecos-engines/tests/clifford_rz_engine_test.rs rename to crates/pecos-engines/tests/stab_vec_engine_test.rs index f5ec2645d..0e639823c 100644 --- a/crates/pecos-engines/tests/clifford_rz_engine_test.rs +++ b/crates/pecos-engines/tests/stab_vec_engine_test.rs @@ -10,18 +10,18 @@ // or implied. See the License for the specific language governing permissions and limitations under // the License. -//! Integration tests for `CliffordRzEngine` via `ByteMessage`. +//! Integration tests for `StabVecEngine` via `ByteMessage`. //! -//! Tests the full `ByteMessage` -> `Engine::process()` -> `CliffordRz` path. +//! Tests the full `ByteMessage` -> `Engine::process()` -> `StabVec` path. use pecos_core::Angle64; use pecos_engines::Engine; use pecos_engines::byte_message::ByteMessageBuilder; -use pecos_engines::quantum::{CliffordRzEngine, StateVecEngine}; +use pecos_engines::quantum::{StabVecEngine, StateVecEngine}; /// Helper: build a circuit, process it, return measurement outcomes. fn run(num_qubits: usize, build: impl FnOnce(&mut ByteMessageBuilder)) -> Vec { - let mut engine = CliffordRzEngine::with_seed(num_qubits, 42); + let mut engine = StabVecEngine::with_seed(num_qubits, 42); let mut builder = ByteMessageBuilder::new(); let _ = builder.for_quantum_operations(); build(&mut builder); @@ -218,7 +218,7 @@ fn prep_resets_qubit() { #[test] fn engine_reset() { - let mut engine = CliffordRzEngine::with_seed(1, 42); + let mut engine = StabVecEngine::with_seed(1, 42); let mut b1 = ByteMessageBuilder::new(); let _ = b1.for_quantum_operations(); @@ -240,7 +240,7 @@ fn engine_reset() { fn deterministic_seed() { let theta = Angle64::from_radians(0.5); let make = |seed: u64| -> Vec { - let mut engine = CliffordRzEngine::with_seed(2, seed); + let mut engine = StabVecEngine::with_seed(2, seed); let mut b = ByteMessageBuilder::new(); let _ = b.for_quantum_operations(); b.h(&[0, 1]); @@ -254,10 +254,10 @@ fn deterministic_seed() { #[test] fn builder_pattern() { - use pecos_engines::clifford_rz; use pecos_engines::quantum_engine_builder::QuantumEngineBuilder; + use pecos_engines::stab_vec; - let mut b = clifford_rz().qubits(2); + let mut b = stab_vec().qubits(2); let mut engine = b.build().unwrap(); engine.set_seed(42); @@ -271,7 +271,7 @@ fn builder_pattern() { } // ============================================================================ -// Round-trip: CliffordRzEngine vs StateVecEngine via ByteMessage +// Round-trip: StabVecEngine vs StateVecEngine via ByteMessage // ============================================================================ /// Build a circuit as a `ByteMessage`, run it on both engines, compare. @@ -290,7 +290,7 @@ fn build_circuit(b: &mut ByteMessageBuilder) { #[test] fn round_trip_statistical_comparison() { - // Run the same circuit on CliffordRzEngine and StateVecEngine many times, + // Run the same circuit on StabVecEngine and StateVecEngine many times, // verify the measurement distributions match. let num_shots = 5000; let num_qubits = 3; @@ -301,9 +301,9 @@ fn round_trip_statistical_comparison() { #[allow(clippy::cast_sign_loss)] // num_shots is a positive literal for seed in 0..num_shots as u64 { - // CliffordRz engine + // StabVec engine { - let mut engine = CliffordRzEngine::with_seed(num_qubits, seed); + let mut engine = StabVecEngine::with_seed(num_qubits, seed); let mut b = ByteMessageBuilder::new(); let _ = b.for_quantum_operations(); build_circuit(&mut b); @@ -331,14 +331,14 @@ fn round_trip_statistical_comparison() { // Compare distributions. Both engines should produce similar statistics. // Allow some deviation due to: // 1. Different RNG consumption patterns between engines - // 2. Pruning in CliffordRz introduces tiny errors + // 2. Pruning in StabVec introduces tiny errors let tolerance = 5.0 / f64::from(num_shots).sqrt(); // ~5 sigma for i in 0..num_outcomes { let crz_prob = f64::from(crz_counts[i]) / f64::from(num_shots); let sv_prob = f64::from(sv_counts[i]) / f64::from(num_shots); assert!( (crz_prob - sv_prob).abs() < tolerance, - "Outcome {i:03b}: CliffordRz={crz_prob:.4}, StateVec={sv_prob:.4}, diff={:.4}, tol={tolerance:.4}", + "Outcome {i:03b}: StabVec={crz_prob:.4}, StateVec={sv_prob:.4}, diff={:.4}, tol={tolerance:.4}", (crz_prob - sv_prob).abs() ); } @@ -349,7 +349,7 @@ fn round_trip_deterministic_clifford_only() { // For a purely Clifford circuit, both engines should give IDENTICAL outcomes // with the same seed (no pruning involved). for seed in 0..100u64 { - let mut crz = CliffordRzEngine::with_seed(3, seed); + let mut crz = StabVecEngine::with_seed(3, seed); let mut sv = StateVecEngine::with_seed(3, seed); let build = |b: &mut ByteMessageBuilder| { diff --git a/crates/pecos-foreign/src/conformance.rs b/crates/pecos-foreign/src/conformance.rs index 593253091..103d80e45 100644 --- a/crates/pecos-foreign/src/conformance.rs +++ b/crates/pecos-foreign/src/conformance.rs @@ -200,12 +200,12 @@ fn test_batch_h(sim: &mut ForeignSimulator, report: &mut ConformanceReport) { pub unsafe extern "C" fn pecos_run_conformance_tests( handle: *mut (), vtable: *const ForeignSimulatorVTable, - _num_qubits: usize, + num_qubits: usize, report_out: *mut ConformanceReport, ) -> i32 { let vtable_copy = unsafe { *vtable }; - let Some(sim) = (unsafe { ForeignSimulator::new(handle, vtable_copy) }) else { + let Some(sim) = (unsafe { ForeignSimulator::new(handle, vtable_copy, num_qubits) }) else { // Version mismatch unsafe { *report_out = ConformanceReport::new() }; return 0; diff --git a/crates/pecos-foreign/src/discovery.rs b/crates/pecos-foreign/src/discovery.rs index 67979c29d..f91758ceb 100644 --- a/crates/pecos-foreign/src/discovery.rs +++ b/crates/pecos-foreign/src/discovery.rs @@ -45,6 +45,8 @@ pub struct PluginDescriptor { /// Opaque handle to the simulator, or null if the plugin does not provide one. pub simulator_handle: *mut (), + /// Number of qubits the simulator was created with. + pub simulator_num_qubits: usize, /// Simulator vtable, or null if the plugin does not provide a simulator. pub simulator_vtable: *const ForeignSimulatorVTable, } @@ -132,6 +134,7 @@ pub fn load_plugin(path: &Path) -> Result { decoder_handle: std::ptr::null_mut(), decoder_vtable: std::ptr::null(), simulator_handle: std::ptr::null_mut(), + simulator_num_qubits: 0, simulator_vtable: std::ptr::null(), }; @@ -163,7 +166,13 @@ pub fn load_plugin(path: &Path) -> Result { // Wrap simulator if provided. let simulator = if !desc.simulator_handle.is_null() && !desc.simulator_vtable.is_null() { let vtable_copy = unsafe { *desc.simulator_vtable }; - unsafe { ForeignSimulator::new(desc.simulator_handle, vtable_copy) } + unsafe { + ForeignSimulator::new( + desc.simulator_handle, + vtable_copy, + desc.simulator_num_qubits, + ) + } } else { None }; diff --git a/crates/pecos-foreign/src/engine.rs b/crates/pecos-foreign/src/engine.rs index bcf1a0fbe..05645b8e4 100644 --- a/crates/pecos-foreign/src/engine.rs +++ b/crates/pecos-foreign/src/engine.rs @@ -20,7 +20,7 @@ use pecos_engines::Engine; use pecos_engines::byte_message::builder::ByteMessageBuilder; use pecos_engines::byte_message::message::ByteMessage; use pecos_engines::quantum::{ - CliffordRzEngine, CoinTossEngine, DensityMatrixEngine, SparseStabEngine, StabilizerEngine, + CoinTossEngine, DensityMatrixEngine, SparseStabEngine, StabVecEngine, StabilizerEngine, StateVecEngine, }; use std::ffi::CStr; @@ -34,7 +34,7 @@ enum EngineInner { StateVec(StateVecEngine), SparseStab(SparseStabEngine), Stabilizer(StabilizerEngine), - CliffordRz(CliffordRzEngine), + StabVec(StabVecEngine), DensityMatrix(DensityMatrixEngine), CoinToss(CoinTossEngine), } @@ -45,7 +45,7 @@ impl EngineInner { Self::StateVec(e) => e.process(input), Self::SparseStab(e) => e.process(input), Self::Stabilizer(e) => e.process(input), - Self::CliffordRz(e) => e.process(input), + Self::StabVec(e) => e.process(input), Self::DensityMatrix(e) => e.process(input), Self::CoinToss(e) => e.process(input), } @@ -56,7 +56,7 @@ impl EngineInner { Self::StateVec(e) => e.reset(), Self::SparseStab(e) => e.reset(), Self::Stabilizer(e) => e.reset(), - Self::CliffordRz(e) => e.reset(), + Self::StabVec(e) => e.reset(), Self::DensityMatrix(e) => e.reset(), Self::CoinToss(e) => e.reset(), } @@ -81,7 +81,7 @@ pub struct PecosCircuitBuilder { /// /// # Arguments /// - `engine_type`: null-terminated C string, one of: -/// `"state_vec"`, `"sparse_stab"`, `"stabilizer"`, `"clifford_rz"`, +/// `"state_vec"`, `"sparse_stab"`, `"stabilizer"`, `"stab_vec"`, /// `"density_matrix"`, `"coin_toss"` /// - `num_qubits`: number of qubits /// - `seed`: RNG seed (0 means use default/random seed) @@ -107,7 +107,7 @@ pub unsafe extern "C" fn pecos_engine_create( "state_vec" => EngineInner::StateVec(StateVecEngine::new(num_qubits)), "sparse_stab" => EngineInner::SparseStab(SparseStabEngine::new(num_qubits)), "stabilizer" => EngineInner::Stabilizer(StabilizerEngine::new(num_qubits)), - "clifford_rz" => EngineInner::CliffordRz(CliffordRzEngine::new(num_qubits)), + "stab_vec" => EngineInner::StabVec(StabVecEngine::new(num_qubits)), "density_matrix" => EngineInner::DensityMatrix(DensityMatrixEngine::new(num_qubits)), "coin_toss" => EngineInner::CoinToss(CoinTossEngine::new(num_qubits)), _ => return std::ptr::null_mut(), @@ -117,7 +117,7 @@ pub unsafe extern "C" fn pecos_engine_create( "state_vec" => EngineInner::StateVec(StateVecEngine::with_seed(num_qubits, seed)), "sparse_stab" => EngineInner::SparseStab(SparseStabEngine::with_seed(num_qubits, seed)), "stabilizer" => EngineInner::Stabilizer(StabilizerEngine::with_seed(num_qubits, seed)), - "clifford_rz" => EngineInner::CliffordRz(CliffordRzEngine::with_seed(num_qubits, seed)), + "stab_vec" => EngineInner::StabVec(StabVecEngine::with_seed(num_qubits, seed)), "density_matrix" => { EngineInner::DensityMatrix(DensityMatrixEngine::with_seed(num_qubits, seed)) } diff --git a/crates/pecos-foreign/src/ffi.rs b/crates/pecos-foreign/src/ffi.rs index f01886b71..10b0b027c 100644 --- a/crates/pecos-foreign/src/ffi.rs +++ b/crates/pecos-foreign/src/ffi.rs @@ -183,9 +183,10 @@ pub unsafe extern "C" fn pecos_foreign_decoder_free(decoder: *mut ForeignDecoder pub unsafe extern "C" fn pecos_foreign_simulator_create( handle: *mut (), vtable: *const ForeignSimulatorVTable, + num_qubits: usize, ) -> *mut ForeignSimulator { let vtable_copy = unsafe { *vtable }; - let Some(sim) = (unsafe { ForeignSimulator::new(handle, vtable_copy) }) else { + let Some(sim) = (unsafe { ForeignSimulator::new(handle, vtable_copy, num_qubits) }) else { return std::ptr::null_mut(); }; Box::into_raw(Box::new(sim)) diff --git a/crates/pecos-foreign/src/simulator.rs b/crates/pecos-foreign/src/simulator.rs index 8d1fdf366..3468a639e 100644 --- a/crates/pecos-foreign/src/simulator.rs +++ b/crates/pecos-foreign/src/simulator.rs @@ -116,6 +116,7 @@ unsafe impl Send for ForeignSimulator {} pub struct ForeignSimulator { handle: *mut (), vtable: ForeignSimulatorVTable, + num_qubits: usize, /// RNG used by PECOS's noise system. The foreign simulator has its own /// internal RNG; this one is for the Rust framework (noise injection, etc.). rng: PecosRng, @@ -133,7 +134,11 @@ impl ForeignSimulator { /// - The foreign simulator is thread-safe (Send) /// /// Returns `None` if the vtable version does not match the expected ABI version. - pub unsafe fn new(handle: *mut (), vtable: ForeignSimulatorVTable) -> Option { + pub unsafe fn new( + handle: *mut (), + vtable: ForeignSimulatorVTable, + num_qubits: usize, + ) -> Option { if vtable.version != crate::version::SIMULATOR_VTABLE_VERSION { log::error!( "Foreign simulator ABI version mismatch: plugin has v{}, PECOS expects v{}", @@ -145,6 +150,7 @@ impl ForeignSimulator { Some(Self { handle, vtable, + num_qubits, rng: PecosRng::seed_from_u64(0), }) } @@ -186,6 +192,10 @@ impl QuantumSimulator for ForeignSimulator { } self } + + fn num_qubits(&self) -> usize { + self.num_qubits + } } impl CliffordGateable for ForeignSimulator { diff --git a/crates/pecos-foreign/tests/conformance_test.rs b/crates/pecos-foreign/tests/conformance_test.rs index 975d0e6ca..9856486de 100644 --- a/crates/pecos-foreign/tests/conformance_test.rs +++ b/crates/pecos-foreign/tests/conformance_test.rs @@ -112,7 +112,7 @@ fn make_real_sim(n: usize) -> ForeignSimulator { destroy: real_destroy, }; - unsafe { ForeignSimulator::new(handle, vtable) }.expect("vtable version should match") + unsafe { ForeignSimulator::new(handle, vtable, n) }.expect("vtable version should match") } #[test] @@ -162,7 +162,7 @@ fn make_broken_sim(n: usize) -> ForeignSimulator { destroy: real_destroy, }; - unsafe { ForeignSimulator::new(handle, vtable) }.expect("vtable version should match") + unsafe { ForeignSimulator::new(handle, vtable, n) }.expect("vtable version should match") } #[test] diff --git a/crates/pecos-foreign/tests/engine_test.rs b/crates/pecos-foreign/tests/engine_test.rs index 57763bb92..a2b79073c 100644 --- a/crates/pecos-foreign/tests/engine_test.rs +++ b/crates/pecos-foreign/tests/engine_test.rs @@ -76,7 +76,7 @@ fn test_engine_create_all_types() { "state_vec", "sparse_stab", "stabilizer", - "clifford_rz", + "stab_vec", "density_matrix", "coin_toss", ] { diff --git a/crates/pecos-foreign/tests/foreign_simulator_test.rs b/crates/pecos-foreign/tests/foreign_simulator_test.rs index 39ad45835..7beb67755 100644 --- a/crates/pecos-foreign/tests/foreign_simulator_test.rs +++ b/crates/pecos-foreign/tests/foreign_simulator_test.rs @@ -92,7 +92,8 @@ fn make_toy_sim(num_qubits: usize) -> ForeignSimulator { destroy: toy_destroy, }; - unsafe { ForeignSimulator::new(handle, vtable) }.expect("vtable version should match") + unsafe { ForeignSimulator::new(handle, vtable, num_qubits) } + .expect("vtable version should match") } #[test] @@ -224,7 +225,7 @@ fn test_foreign_simulator_version_mismatch() { }; // Should return None on version mismatch - let result = unsafe { ForeignSimulator::new(handle, vtable) }; + let result = unsafe { ForeignSimulator::new(handle, vtable, 3) }; assert!(result.is_none(), "wrong version should return None"); unsafe { diff --git a/crates/pecos-foreign/tests/neo_integration_test.rs b/crates/pecos-foreign/tests/neo_integration_test.rs index a6232d4c6..24f8ab997 100644 --- a/crates/pecos-foreign/tests/neo_integration_test.rs +++ b/crates/pecos-foreign/tests/neo_integration_test.rs @@ -89,7 +89,8 @@ fn make_toy_sim(num_qubits: usize) -> ForeignSimulator { destroy: toy_destroy, }; - unsafe { ForeignSimulator::new(handle, vtable) }.expect("vtable version should match") + unsafe { ForeignSimulator::new(handle, vtable, num_qubits) } + .expect("vtable version should match") } #[test] diff --git a/crates/pecos-fusion-blossom/Cargo.toml b/crates/pecos-fusion-blossom/Cargo.toml index 3c4d73b99..9ebfc8370 100644 --- a/crates/pecos-fusion-blossom/Cargo.toml +++ b/crates/pecos-fusion-blossom/Cargo.toml @@ -16,6 +16,7 @@ pecos-decoder-core.workspace = true ndarray.workspace = true thiserror.workspace = true fusion-blossom.workspace = true +serde_json.workspace = true [lib] name = "pecos_fusion_blossom" diff --git a/crates/pecos-fusion-blossom/examples/fusion_blossom_usage.rs b/crates/pecos-fusion-blossom/examples/fusion_blossom_usage.rs index 1c049ce75..ec3fe5128 100644 --- a/crates/pecos-fusion-blossom/examples/fusion_blossom_usage.rs +++ b/crates/pecos-fusion-blossom/examples/fusion_blossom_usage.rs @@ -85,7 +85,7 @@ fn main() -> Result<(), Box> { let result = decoder.decode(&syndrome.view())?; println!("Decoded observables: {:?}", result.observable); println!("Total weight: {:.2}", result.weight); - println!("Observable errors detected: "); + println!("Logical observable errors detected: "); for (i, &obs) in result.observable.iter().enumerate() { if obs != 0 { println!(" - Observable {i} flipped"); diff --git a/crates/pecos-fusion-blossom/src/core_traits.rs b/crates/pecos-fusion-blossom/src/core_traits.rs index cded1dada..c0a0d451b 100644 --- a/crates/pecos-fusion-blossom/src/core_traits.rs +++ b/crates/pecos-fusion-blossom/src/core_traits.rs @@ -33,6 +33,165 @@ impl Decoder for FusionBlossomDecoder { } } +/// Implement `ObservableDecoder` for `FusionBlossomDecoder`. +/// +/// Uses the fast decode path with pre-computed observable bitmasks. +impl pecos_decoder_core::ObservableDecoder for FusionBlossomDecoder { + fn decode_to_observables( + &mut self, + syndrome: &[u8], + ) -> Result { + self.decode_to_obs_mask(syndrome) + .map_err(|e| pecos_decoder_core::DecoderError::DecodingFailed(e.to_string())) + } +} + +/// Implement `ObservableErasureDecoder` for `FusionBlossomDecoder`. +/// +/// Neutral atom erasure support: erased edges are marked in the syndrome data, +/// causing the solver to treat them as known errors (zero weight). +impl pecos_decoder_core::erasure::ObservableErasureDecoder for FusionBlossomDecoder { + fn decode_with_erasures( + &mut self, + syndrome: &[u8], + erasure_edges: &[usize], + ) -> Result { + if erasure_edges.is_empty() { + return self + .decode_to_obs_mask(syndrome) + .map_err(|e| pecos_decoder_core::DecoderError::DecodingFailed(e.to_string())); + } + + let defects: Vec = syndrome + .iter() + .enumerate() + .filter_map(|(i, &v)| if v != 0 { Some(i) } else { None }) + .collect(); + + if defects.is_empty() && erasure_edges.is_empty() { + return Ok(0); + } + + let syndrome_data = SyndromeData::with_erasures(defects, erasure_edges.to_vec()); + + let result = self + .decode_with_options(syndrome_data, DecodingOptions::default()) + .map_err(|e| pecos_decoder_core::DecoderError::DecodingFailed(e.to_string()))?; + + let edge_indices: Vec = result.matched_edges.iter().copied().collect(); + Ok(self.obs_mask_from_edges(&edge_indices)) + } +} + +/// Implement `MatchingDecoder` for `FusionBlossomDecoder`. +/// +/// Enables the two-pass correlated DGR decode by exposing which edges +/// were matched and accepting per-shot dynamic weight adjustments. +impl pecos_decoder_core::correlated_decoder::MatchingDecoder for FusionBlossomDecoder { + fn decode_with_matching( + &mut self, + syndrome: &[u8], + ) -> Result<(u64, Vec), pecos_decoder_core::DecoderError> { + // Extract defects + let defects: Vec = syndrome + .iter() + .enumerate() + .filter_map(|(i, &v)| if v != 0 { Some(i) } else { None }) + .collect(); + + if defects.is_empty() { + return Ok((0, Vec::new())); + } + + let syndrome_data = SyndromeData::from_defects(defects); + let result = self + .decode_with_options(syndrome_data, DecodingOptions::default()) + .map_err(|e| pecos_decoder_core::DecoderError::DecodingFailed(e.to_string()))?; + + let edge_indices: Vec = result.matched_edges.iter().copied().collect(); + let mask = self.obs_mask_from_edges(&edge_indices); + + Ok((mask, edge_indices)) + } + + fn decode_with_weights( + &mut self, + syndrome: &[u8], + weights: &[f64], + ) -> Result<(u64, Vec), pecos_decoder_core::DecoderError> { + let defects: Vec = syndrome + .iter() + .enumerate() + .filter_map(|(i, &v)| if v != 0 { Some(i) } else { None }) + .collect(); + + if defects.is_empty() { + return Ok((0, Vec::new())); + } + + // Convert f64 weights to Fusion Blossom's integer dynamic weights. + // FB uses integer weights with 1000x scaling, must be even. + // Only include edges whose weight differs from the original to avoid + // disrupting the solver with redundant overrides. + #[allow(clippy::cast_possible_truncation)] + let dynamic_weights: Vec<(usize, i32)> = weights + .iter() + .enumerate() + .filter_map(|(i, &w)| { + // Clamp to positive (FB doesn't handle negative weights) + let clamped = w.max(0.01); + let int_w = ((clamped * 1000.0) as i32 / 2) * 2; + // Only include if it's a real weight (not a huge default) + if int_w > 0 && int_w < 40_000 { + Some((i, int_w)) + } else { + None + } + }) + .collect(); + + let mut syndrome_data = SyndromeData::from_defects(defects); + if !dynamic_weights.is_empty() { + syndrome_data.dynamic_weights = Some(dynamic_weights); + } + + let result = self + .decode_with_options(syndrome_data, DecodingOptions::default()) + .map_err(|e| pecos_decoder_core::DecoderError::DecodingFailed(e.to_string()))?; + + let edge_indices: Vec = result.matched_edges.iter().copied().collect(); + let mask = self.obs_mask_from_edges(&edge_indices); + + Ok((mask, edge_indices)) + } + + fn num_edges(&self) -> usize { + self.num_edges() + } +} + +impl pecos_decoder_core::correlated_decoder::EdgeTrackingDecoder for FusionBlossomDecoder { + fn edge_node1(&self, edge_idx: usize) -> u32 { + self.edge_endpoints(edge_idx).map_or(0, |(n1, _, _)| n1) + } + + fn edge_node2(&self, edge_idx: usize) -> u32 { + self.edge_endpoints(edge_idx).map_or(0, |(_, n2, _)| n2) + } + + fn edge_weight(&self, edge_idx: usize) -> f64 { + self.edge_endpoints(edge_idx).map_or(0.0, |(_, _, w)| w) + } + + fn edge_obs_mask(&self, edge_idx: usize) -> u64 { + self.edge_obs_mask(edge_idx) + } + + fn num_detectors(&self) -> usize { + self.num_nodes() + } +} + /// Implement `DecodingResultTrait` for `FusionBlossom`'s `DecodingResult` impl DecodingResultTrait for DecodingResult { fn is_successful(&self) -> bool { @@ -40,6 +199,10 @@ impl DecodingResultTrait for DecodingResult { true } + fn correction(&self) -> &[u8] { + &self.observable + } + fn cost(&self) -> Option { Some(self.weight) } diff --git a/crates/pecos-fusion-blossom/src/decoder.rs b/crates/pecos-fusion-blossom/src/decoder.rs index abe3bc0c7..80ed85ba3 100644 --- a/crates/pecos-fusion-blossom/src/decoder.rs +++ b/crates/pecos-fusion-blossom/src/decoder.rs @@ -6,8 +6,8 @@ use fusion_blossom::{ CircuitLevelPlanarCode, CodeCapacityPlanarCode, CodeCapacityRotatedCode, ExampleCode, PhenomenologicalPlanarCode, PhenomenologicalRotatedCode, }, - mwpm_solver::{LegacySolverSerial, PrimalDualSolver, SolverSerial}, - util::{EdgeIndex, SolverInitializer, SyndromePattern, VertexIndex, Weight}, + mwpm_solver::{LegacySolverSerial, SolverDualParallel, SolverSerial}, + util::{EdgeIndex, PartitionConfig, SolverInitializer, SyndromePattern, VertexIndex, Weight}, }; use ndarray::{Array2, ArrayView1}; use std::collections::HashMap; @@ -21,6 +21,8 @@ pub enum SolverType { /// Serial solver (improved performance) #[default] Serial, + /// Parallel solver (intra-shot parallelism via partitioning) + Parallel, } /// Configuration for Fusion Blossom decoder @@ -179,6 +181,18 @@ pub enum StandardCode { enum Solver { Legacy(LegacySolverSerial), Serial(SolverSerial), + Parallel(SolverDualParallel), +} + +/// Pre-parsed correlated DEM for fast repeated FB construction. +#[derive(Clone)] +pub struct ParsedCorrelatedDem { + /// Number of detector nodes. + pub num_detectors: usize, + /// Number of observables. + pub num_observables: usize, + /// Per mechanism: (`detector_indices`, `observable_indices`, `original_weight`). + pub mechanisms: Vec<(Vec, Vec, f64)>, } /// Fusion Blossom decoder @@ -186,6 +200,8 @@ pub struct FusionBlossomDecoder { config: FusionBlossomConfig, /// Map from edge index to observable mask edge_observables: HashMap>, + /// Pre-computed observable bitmask per edge (for fast decode path) + edge_obs_masks: Vec, /// Number of nodes (detectors) num_nodes: usize, /// Virtual boundary node (if used) @@ -193,11 +209,17 @@ pub struct FusionBlossomDecoder { /// Edges to be added to the initializer weighted_edges: Vec<(VertexIndex, VertexIndex, Weight)>, /// Virtual vertices - virtual_vertices: Vec, + pub virtual_vertices: Vec, /// Cached solver instance for reuse solver: Option, /// Cached initializer initializer: Option, + /// Partition config for parallel solver (None for serial) + partition_config: Option, + /// Reusable buffer for padded syndrome (avoids per-shot allocation) + _syndrome_buf: Vec, + /// Reusable buffer for defect vertices + defect_buf: Vec, } impl FusionBlossomDecoder { @@ -235,15 +257,301 @@ impl FusionBlossomDecoder { Ok(Self { config, edge_observables: HashMap::new(), + edge_obs_masks: Vec::new(), + partition_config: None, num_nodes, boundary_node: None, weighted_edges: Vec::new(), virtual_vertices: Vec::new(), solver: None, initializer: None, + _syndrome_buf: vec![0u8; num_nodes + 1], // +1 for possible boundary node + defect_buf: Vec::new(), }) } + /// Create decoder from a `DemMatchingGraph`. + /// + /// # Errors + /// + /// Returns error if the graph is empty or construction fails. + pub fn from_matching_graph(graph: &pecos_decoder_core::dem::DemMatchingGraph) -> Result { + let config = FusionBlossomConfig { + num_nodes: Some(graph.num_detectors), + num_observables: graph.num_observables, + ..Default::default() + }; + let mut decoder = Self::new(config)?; + for edge in &graph.edges { + let obs: Vec = edge.observables.iter().map(|&o| o as usize).collect(); + match edge.node2 { + Some(n2) => { + decoder.add_edge(edge.node1 as usize, n2 as usize, &obs, Some(edge.weight))?; + } + None => { + decoder.add_boundary_edge(edge.node1 as usize, &obs, Some(edge.weight))?; + } + } + } + decoder.build_obs_masks(); + Ok(decoder) + } + + /// Create decoder from a DEM string. + /// + /// # Errors + /// + /// Returns error if the DEM is malformed. + pub fn from_dem(dem: &str) -> Result { + let graph = pecos_decoder_core::dem::DemMatchingGraph::from_dem_str(dem) + .map_err(|e| FusionBlossomError::Configuration(e.to_string()))?; + Self::from_matching_graph(&graph) + } + + /// Parse a DEM string into a reusable structure for correlated FB construction. + /// + /// # Errors + /// + /// Returns error if the DEM is malformed. + pub fn parse_correlated_dem(dem: &str) -> Result { + use pecos_decoder_core::dem::DemCheckMatrix; + + let dcm = DemCheckMatrix::from_dem_str(dem) + .map_err(|e| FusionBlossomError::Configuration(e.to_string()))?; + + let mut mechanisms = Vec::new(); + for m in 0..dcm.num_mechanisms { + let p = dcm.error_priors[m]; + if p <= 0.0 { + continue; + } + + let detectors: Vec = (0..dcm.num_detectors) + .filter(|&d| dcm.check_matrix[[d, m]] != 0) + .collect(); + + let obs: Vec = (0..dcm.num_observables) + .filter(|&o| dcm.observable_matrix[[o, m]] != 0) + .collect(); + + let weight = if p < 1.0 { ((1.0 - p) / p).ln() } else { 0.0 }; + + // Only graphlike (1-2 detector) mechanisms. + if detectors.len() <= 2 { + mechanisms.push((detectors, obs, weight)); + } + } + + Ok(ParsedCorrelatedDem { + num_detectors: dcm.num_detectors, + num_observables: dcm.num_observables, + mechanisms, + }) + } + + /// Build a correlated FB decoder from pre-parsed data with optional weight perturbation. + /// + /// `weight_factors[i]` multiplies the i-th mechanism's weight. Pass `None` for no perturbation. + /// Duplicate edges (same endpoints) are merged by keeping the lowest weight + /// (highest probability) mechanism's observable — matching PM's INDEPENDENT strategy. + /// + /// # Errors + /// + /// Returns error if construction fails. + pub fn from_parsed_correlated( + parsed: &ParsedCorrelatedDem, + weight_factors: Option<&[f64]>, + ) -> Result { + use std::collections::BTreeMap; + + let config = FusionBlossomConfig { + num_nodes: Some(parsed.num_detectors), + num_observables: parsed.num_observables, + ..Default::default() + }; + let mut decoder = Self::new(config)?; + + // Deduplicate edges: merge by independent-union probability, + // first-observable-wins (stable under perturbation). + // Key: (min_node, max_node, is_boundary). Value: (obs, prob, best_prob). + struct EdgeInfo { + obs: Vec, + prob: f64, + best_prob: f64, + } + let mut edge_map: BTreeMap<(usize, usize, bool), EdgeInfo> = BTreeMap::new(); + + for (i, (detectors, obs, base_weight)) in parsed.mechanisms.iter().enumerate() { + let weight = if let Some(factors) = weight_factors { + if i < factors.len() { + (base_weight * factors[i]).max(0.01) + } else { + *base_weight + } + } else { + *base_weight + }; + // Convert weight to probability for merging. + let prob = 1.0 / (1.0 + weight.exp()); + + let key = match detectors.len() { + 1 => (detectors[0], usize::MAX, true), + 2 => { + let (a, b) = if detectors[0] < detectors[1] { + (detectors[0], detectors[1]) + } else { + (detectors[1], detectors[0]) + }; + (a, b, false) + } + _ => continue, + }; + + let entry = edge_map.entry(key).or_insert_with(|| EdgeInfo { + obs: obs.clone(), + prob, + best_prob: prob, + }); + // Independent union: P(A or B) = P(A) + P(B) - P(A)*P(B) + entry.prob = entry.prob + prob - entry.prob * prob; + if prob > entry.best_prob { + entry.obs = obs.clone(); + entry.best_prob = prob; + } + } + + for ((n1, n2, is_boundary), info) in &edge_map { + // Convert combined probability back to weight. + let p = info.prob.clamp(1e-15, 1.0 - 1e-15); + let weight = ((1.0 - p) / p).ln(); + if *is_boundary { + decoder.add_boundary_edge(*n1, &info.obs, Some(weight))?; + } else { + decoder.add_edge(*n1, *n2, &info.obs, Some(weight))?; + } + } + + decoder.build_obs_masks(); + Ok(decoder) + } + + /// Create decoder from a pre-parsed `DemCheckMatrix` preserving all mechanisms. + /// + /// Like `from_dem_correlated` but skips DEM string parsing. + /// Optionally applies multiplicative weight perturbation via `weight_factors`. + /// + /// # Errors + /// + /// Returns error if construction fails. + pub fn from_check_matrix_correlated( + dcm: &pecos_decoder_core::dem::DemCheckMatrix, + weight_factors: Option<&[f64]>, + ) -> Result { + // Use Legacy solver which tolerates duplicate edges (no assertion). + let config = FusionBlossomConfig { + num_nodes: Some(dcm.num_detectors), + num_observables: dcm.num_observables, + solver_type: SolverType::Legacy, + ..Default::default() + }; + let mut decoder = Self::new(config)?; + + for m in 0..dcm.num_mechanisms { + let p = dcm.error_priors[m]; + if p <= 0.0 { + continue; + } + + let detectors: Vec = (0..dcm.num_detectors) + .filter(|&d| dcm.check_matrix[[d, m]] != 0) + .collect(); + + let obs: Vec = (0..dcm.num_observables) + .filter(|&o| dcm.observable_matrix[[o, m]] != 0) + .collect(); + + let mut weight = if p < 1.0 { ((1.0 - p) / p).ln() } else { 0.0 }; + + if let Some(factors) = weight_factors + && m < factors.len() { + weight *= factors[m]; + weight = weight.max(0.01); + } + + match detectors.len() { + 1 => { + decoder.add_boundary_edge(detectors[0], &obs, Some(weight))?; + } + 2 => { + decoder.add_edge(detectors[0], detectors[1], &obs, Some(weight))?; + } + _ => {} + } + } + + decoder.build_obs_masks(); + Ok(decoder) + } + + /// Create decoder from a DEM string preserving all mechanisms. + /// + /// Unlike `from_dem` which uses `DemMatchingGraph` (merges duplicate edges), + /// this uses `DemCheckMatrix` to keep every mechanism as a separate edge. + /// This preserves X-Z correlations from Y errors, similar to `PyMatching`'s + /// `enable_correlations` mode. + /// + /// Only 2-detector mechanisms are included (3+ detector hyperedges are + /// skipped since FB is a matching decoder). + /// + /// # Errors + /// + /// Returns error if the DEM is malformed. + pub fn from_dem_correlated(dem: &str) -> Result { + use pecos_decoder_core::dem::DemCheckMatrix; + + let dcm = DemCheckMatrix::from_dem_str(dem) + .map_err(|e| FusionBlossomError::Configuration(e.to_string()))?; + + let config = FusionBlossomConfig { + num_nodes: Some(dcm.num_detectors), + num_observables: dcm.num_observables, + ..Default::default() + }; + let mut decoder = Self::new(config)?; + + for m in 0..dcm.num_mechanisms { + let p = dcm.error_priors[m]; + if p <= 0.0 { + continue; + } + + let detectors: Vec = (0..dcm.num_detectors) + .filter(|&d| dcm.check_matrix[[d, m]] != 0) + .collect(); + + // Only handle 2-detector (graphlike) mechanisms. + // 1-detector = boundary, 3+ = hyperedge (skip). + let obs: Vec = (0..dcm.num_observables) + .filter(|&o| dcm.observable_matrix[[o, m]] != 0) + .collect(); + + let weight = if p < 1.0 { ((1.0 - p) / p).ln() } else { 0.0 }; + + match detectors.len() { + 1 => { + decoder.add_boundary_edge(detectors[0], &obs, Some(weight))?; + } + 2 => { + decoder.add_edge(detectors[0], detectors[1], &obs, Some(weight))?; + } + _ => {} // Skip hyperedges + } + } + + decoder.build_obs_masks(); + Ok(decoder) + } + /// Create decoder from a standard QEC code /// /// # Errors @@ -331,12 +639,16 @@ impl FusionBlossomDecoder { ..config }, edge_observables, + edge_obs_masks: Vec::new(), num_nodes, boundary_node: None, weighted_edges: initializer.weighted_edges.clone(), virtual_vertices: initializer.virtual_vertices.clone(), solver: None, initializer: Some(initializer), + partition_config: None, + _syndrome_buf: vec![0u8; num_nodes + 1], + defect_buf: Vec::new(), }; // Identify boundary nodes from virtual vertices @@ -508,9 +820,21 @@ impl FusionBlossomDecoder { Ok(decoder) } - /// Clear the solver state for reuse + /// Set partition config for parallel solving. + /// + /// The partition config defines how the matching graph is split across + /// threads for intra-shot parallelism. + pub fn set_partition_config(&mut self, config: PartitionConfig) { + self.partition_config = Some(config); + self.config.solver_type = SolverType::Parallel; + self.solver = None; // force solver recreation + } + + /// Clear the solver state for reuse between decodes. + /// + /// The Serial solver is cleared inline after each solve. This method + /// exists for external callers and the Legacy solver fallback. pub fn clear(&mut self) { - // For Fusion Blossom, we need to recreate the solver to clear state self.solver = None; } @@ -544,6 +868,18 @@ impl FusionBlossomDecoder { let solver = match self.config.solver_type { SolverType::Legacy => Solver::Legacy(LegacySolverSerial::new(&initializer)), SolverType::Serial => Solver::Serial(SolverSerial::new(&initializer)), + SolverType::Parallel => { + let partition_info = self + .partition_config + .as_ref() + .expect("partition_config must be set for Parallel solver") + .info(); + Solver::Parallel(SolverDualParallel::new( + &initializer, + &partition_info, + serde_json::json!({}), + )) + } }; self.solver = Some(solver); @@ -561,7 +897,7 @@ impl FusionBlossomDecoder { pub fn decode_with_options( &mut self, syndrome_data: SyndromeData, - options: DecodingOptions, + _options: DecodingOptions, ) -> Result { // Convert defects to VertexIndex let defect_vertices: Vec = syndrome_data @@ -602,34 +938,27 @@ impl FusionBlossomDecoder { SyndromePattern::new_vertices(defect_vertices) }; - // Get or create solver + // Get or create solver, solve, extract results, then clear for next use. let solver = self.get_or_create_solver(); - // Solve and get perfect matching if requested let (matched_edges, perfect_matching_info) = match solver { Solver::Legacy(s) => { let edges = s.solve_subgraph(&syndrome_pattern); - let pm_info = if options.include_perfect_matching { - // Legacy solver doesn't have easy access to perfect matching - None - } else { - None - }; - (edges, pm_info) + (edges, None) } Solver::Serial(s) => { + use fusion_blossom::mwpm_solver::PrimalDualSolver; s.solve(&syndrome_pattern); let edges = s.subgraph(); - - let pm_info = if options.include_perfect_matching { - // For Serial solver, we can't easily get perfect matching details - // without accessing internal structures - None - } else { - None - }; - - (edges, pm_info) + s.clear(); + (edges, None) + } + Solver::Parallel(s) => { + use fusion_blossom::mwpm_solver::PrimalDualSolver; + s.solve(&syndrome_pattern); + let edges = s.subgraph(); + s.clear(); + (edges, None) } }; @@ -712,7 +1041,13 @@ impl FusionBlossomDecoder { self.initializer = None; } - /// Get number of nodes + /// Get the boundary node index, if one exists. + #[must_use] + pub fn boundary_node(&self) -> Option { + self.boundary_node + } + + /// Get number of nodes. #[must_use] pub fn num_nodes(&self) -> usize { self.num_nodes @@ -723,4 +1058,98 @@ impl FusionBlossomDecoder { pub fn num_edges(&self) -> usize { self.weighted_edges.len() } + + /// Get node endpoints and weight of an edge by index. + #[must_use] + pub fn edge_endpoints(&self, edge_idx: usize) -> Option<(u32, u32, f64)> { + self.weighted_edges + .get(edge_idx) + .map(|&(n1, n2, w)| (n1 as u32, n2 as u32, (w as f64) / 1000.0)) + } + + /// Get per-edge observable bitmask. + #[must_use] + pub fn edge_obs_mask(&self, edge_idx: usize) -> u64 { + self.edge_obs_masks.get(edge_idx).copied().unwrap_or(0) + } + + /// Compute observable mask from a set of matched edge indices. + /// Uses pre-computed bitmasks (builds them on first call). + pub fn obs_mask_from_edges(&mut self, matched_edges: &[usize]) -> u64 { + if self.edge_obs_masks.is_empty() && !self.edge_observables.is_empty() { + self.build_obs_masks(); + } + let mut mask = 0u64; + for &edge_idx in matched_edges { + if let Some(&m) = self.edge_obs_masks.get(edge_idx) { + mask ^= m; + } + } + mask + } + + /// Build pre-computed observable bitmasks for fast decode path. + /// Call once after all edges are added. + pub fn build_obs_masks(&mut self) { + let n = self.weighted_edges.len(); + self.edge_obs_masks = vec![0u64; n]; + for (&edge_idx, obs_indices) in &self.edge_observables { + if edge_idx < n { + let mut mask = 0u64; + for &obs_idx in obs_indices { + mask |= 1 << obs_idx; + } + self.edge_obs_masks[edge_idx] = mask; + } + } + } + + /// Fast decode: syndrome bytes -> observable bitmask. + /// Uses reusable buffers and pre-computed observable masks. + /// Handles padding for boundary node internally. + pub fn decode_to_obs_mask(&mut self, syndrome: &[u8]) -> Result { + // Build obs masks on first call + if self.edge_obs_masks.is_empty() && !self.edge_observables.is_empty() { + self.build_obs_masks(); + } + + // Fill defect buffer from syndrome (pad to num_nodes for boundary) + self.defect_buf.clear(); + for (i, &v) in syndrome.iter().enumerate() { + if v != 0 { + self.defect_buf.push(i as VertexIndex); + } + } + // No defects in padding region (boundary node always 0) + + if self.defect_buf.is_empty() { + return Ok(0); + } + + let syndrome_pattern = SyndromePattern::new_vertices(self.defect_buf.clone()); + let solver = self.get_or_create_solver(); + + let matched_edges = match solver { + Solver::Legacy(s) => s.solve_subgraph(&syndrome_pattern), + Solver::Serial(s) => { + use fusion_blossom::mwpm_solver::PrimalDualSolver; + s.solve(&syndrome_pattern); + let edges = s.subgraph(); + s.clear(); + edges + } + Solver::Parallel(s) => { + use fusion_blossom::mwpm_solver::PrimalDualSolver; + s.solve(&syndrome_pattern); + let edges = s.subgraph(); + s.clear(); + edges + } + }; + + // Compute observable mask using pre-computed bitmasks + let edge_indices: Vec = matched_edges.iter().copied().collect(); + let mask = self.obs_mask_from_edges(&edge_indices); + Ok(mask) + } } diff --git a/crates/pecos-fusion-blossom/src/lib.rs b/crates/pecos-fusion-blossom/src/lib.rs index b4f09f3da..bbc122a18 100644 --- a/crates/pecos-fusion-blossom/src/lib.rs +++ b/crates/pecos-fusion-blossom/src/lib.rs @@ -19,6 +19,9 @@ pub mod errors; pub use builder::FusionBlossomBuilder; pub use decoder::{ DecodingOptions, DecodingResult, FusionBlossomConfig, FusionBlossomDecoder, - PerfectMatchingInfo, SolverType, StandardCode, SyndromeData, + ParsedCorrelatedDem, PerfectMatchingInfo, SolverType, StandardCode, SyndromeData, }; pub use errors::FusionBlossomError; + +// Re-export partition types from fusion-blossom for parallel solver +pub use fusion_blossom::util::{PartitionConfig, VertexRange}; diff --git a/crates/pecos-gpu-sims/examples/benchmark_influence_sampler.rs b/crates/pecos-gpu-sims/examples/benchmark_influence_sampler.rs index ae000b21e..dbd23c3e8 100644 --- a/crates/pecos-gpu-sims/examples/benchmark_influence_sampler.rs +++ b/crates/pecos-gpu-sims/examples/benchmark_influence_sampler.rs @@ -42,15 +42,15 @@ fn create_test_influence_map(num_locations: usize, num_detectors: usize) -> GpuI GpuInfluenceMapData { num_locations: num_locations as u32, num_detectors: num_detectors as u32, - num_logicals: 2, + num_dem_outputs: 2, detector_offsets_x, detector_data_x, detector_offsets_y, detector_data_y, detector_offsets_z, detector_data_z, - // Logicals: location 0 X -> log 0, location 1 X -> log 1 - logical_offsets_x: { + // DEM outputs: location 0 X -> L0, location 1 X -> L1 + dem_output_offsets_x: { let mut v = vec![0u32; num_locations + 1]; if num_locations > 0 { v[1] = 1; @@ -63,27 +63,27 @@ fn create_test_influence_map(num_locations: usize, num_detectors: usize) -> GpuI } v }, - logical_data_x: vec![0, 1], - logical_offsets_y: vec![0; num_locations + 1], - logical_data_y: vec![], - logical_offsets_z: vec![0; num_locations + 1], - logical_data_z: vec![], + dem_output_data_x: vec![0, 1], + dem_output_offsets_y: vec![0; num_locations + 1], + dem_output_data_y: vec![], + dem_output_offsets_z: vec![0; num_locations + 1], + dem_output_data_z: vec![], } } -/// Simple CPU sampler for comparison (mirrors the pecos-qec `NoisySampler` logic) +/// Simple CPU sampler for comparison (mirrors the pecos-qec `DemSampler` logic) struct CpuSampler { num_locations: usize, num_detectors: usize, - num_logicals: usize, + num_dem_outputs: usize, detector_offsets_x: Vec, detector_data_x: Vec, detector_offsets_y: Vec, detector_data_y: Vec, detector_offsets_z: Vec, detector_data_z: Vec, - logical_offsets_x: Vec, - logical_data_x: Vec, + dem_output_offsets_x: Vec, + dem_output_data_x: Vec, rng_state: u64, } @@ -92,15 +92,15 @@ impl CpuSampler { Self { num_locations: map.num_locations as usize, num_detectors: map.num_detectors as usize, - num_logicals: map.num_logicals as usize, + num_dem_outputs: map.num_dem_outputs as usize, detector_offsets_x: map.detector_offsets_x.clone(), detector_data_x: map.detector_data_x.clone(), detector_offsets_y: map.detector_offsets_y.clone(), detector_data_y: map.detector_data_y.clone(), detector_offsets_z: map.detector_offsets_z.clone(), detector_data_z: map.detector_data_z.clone(), - logical_offsets_x: map.logical_offsets_x.clone(), - logical_data_x: map.logical_data_x.clone(), + dem_output_offsets_x: map.dem_output_offsets_x.clone(), + dem_output_data_x: map.dem_output_data_x.clone(), rng_state: seed, } } @@ -120,11 +120,11 @@ impl CpuSampler { #[allow(clippy::cast_sign_loss, clippy::cast_possible_truncation)] // probability in [0,1] maps to [0, u32::MAX] let threshold = (p_error * f64::from(u32::MAX)) as u32; - let mut logical_errors = 0; + let mut logical_error_count = 0; for _ in 0..num_shots { let mut detector_flips = vec![0u8; self.num_detectors.max(1)]; - let mut logical_flips = vec![0u8; self.num_logicals.max(1)]; + let mut dem_output_flips = vec![0u8; self.num_dem_outputs.max(1)]; for loc in 0..self.num_locations { let rand = self.next_u32(); @@ -135,7 +135,7 @@ impl CpuSampler { // Sample Pauli type let pauli = self.next_u32() % 3; - // Get affected detectors and logicals + // Get affected detectors and DEM outputs let (det_start, det_end, det_data) = match pauli { 0 => ( self.detector_offsets_x[loc] as usize, @@ -161,25 +161,25 @@ impl CpuSampler { } } - // Only X affects logicals in our test map + // Only X affects DEM outputs in our test map if pauli == 0 { - let log_start = self.logical_offsets_x[loc] as usize; - let log_end = self.logical_offsets_x[loc + 1] as usize; - for i in log_start..log_end { - let log_idx = self.logical_data_x[i] as usize; - if log_idx < logical_flips.len() { - logical_flips[log_idx] ^= 1; + let dem_output_start = self.dem_output_offsets_x[loc] as usize; + let dem_output_end = self.dem_output_offsets_x[loc + 1] as usize; + for i in dem_output_start..dem_output_end { + let dem_output_idx = self.dem_output_data_x[i] as usize; + if dem_output_idx < dem_output_flips.len() { + dem_output_flips[dem_output_idx] ^= 1; } } } } - if logical_flips.contains(&1) { - logical_errors += 1; + if dem_output_flips.contains(&1) { + logical_error_count += 1; } } - logical_errors + logical_error_count } } @@ -195,8 +195,8 @@ fn benchmark_gpu( let result = sampler.sample_uniform(num_shots, p_error); let elapsed = start.elapsed(); - let logical_errors = result.count_logical_errors(); - (elapsed, logical_errors) + let logical_error_count = result.count_logical_errors(); + (elapsed, logical_error_count) } fn benchmark_cpu( @@ -208,10 +208,10 @@ fn benchmark_cpu( let mut sampler = CpuSampler::new(map, seed); let start = Instant::now(); - let logical_errors = sampler.sample(num_shots, p_error); + let logical_error_count = sampler.sample(num_shots, p_error); let elapsed = start.elapsed(); - (elapsed, logical_errors) + (elapsed, logical_error_count) } fn main() { diff --git a/crates/pecos-gpu-sims/examples/cpu_vs_gpu_comparison.rs b/crates/pecos-gpu-sims/examples/cpu_vs_gpu_comparison.rs index 1bdd2b61c..e5a948c33 100644 --- a/crates/pecos-gpu-sims/examples/cpu_vs_gpu_comparison.rs +++ b/crates/pecos-gpu-sims/examples/cpu_vs_gpu_comparison.rs @@ -4,7 +4,7 @@ use pecos_gpu_sims::{GpuInfluenceMapData, GpuInfluenceSampler}; use pecos_qec::fault_tolerance::InfluenceBuilder; -use pecos_qec::fault_tolerance::noisy_sampler::{NoisySampler, UniformNoiseModel}; +use pecos_qec::fault_tolerance::dem_builder::DemSampler; use pecos_quantum::DagCircuit; use std::time::Instant; @@ -91,8 +91,8 @@ fn main() { let num_data = distance * distance; // Build influence map - let logical_qubits: Vec = (0..num_data).collect(); - let builder = InfluenceBuilder::new(&circuit).with_logical_z(logical_qubits); + let tracked_op_qubits: Vec = (0..num_data).collect(); + let builder = InfluenceBuilder::new(&circuit).with_z(&tracked_op_qubits); let influence_map = builder.build(); let num_locations = influence_map.locations.len(); @@ -101,32 +101,46 @@ fn main() { let ( num_loc, num_det, - num_log, + num_dem_outputs, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, det_data_z, - log_off_x, - log_data_x, - log_off_y, - log_data_y, - log_off_z, - log_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ) = influence_map.export_csr(); let gpu_map = GpuInfluenceMapData::from_csr( - num_loc, num_det, num_log, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, - det_data_z, log_off_x, log_data_x, log_off_y, log_data_y, log_off_z, log_data_z, + num_loc, + num_det, + num_dem_outputs, + det_off_x, + det_data_x, + det_off_y, + det_data_y, + det_off_z, + det_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ); // CPU benchmark - let noise = UniformNoiseModel::depolarizing(p_error); - let mut cpu_sampler = NoisySampler::new(&influence_map, noise, seed); + let num_loc = influence_map.locations.len(); + let probs = vec![p_error; num_loc]; + let cpu_sampler = DemSampler::from_influence_map(&influence_map, &probs); let cpu_start = Instant::now(); - let _ = cpu_sampler.sample(num_shots as usize); + let _ = cpu_sampler.sample_statistics(num_shots as usize, seed); let cpu_time = cpu_start.elapsed(); // GPU benchmark (with warmup) @@ -165,38 +179,51 @@ fn main() { let circuit = build_surface_code_grid(distance, num_rounds); let num_data = distance * distance; - let logical_qubits: Vec = (0..num_data).collect(); - let builder = InfluenceBuilder::new(&circuit).with_logical_z(logical_qubits); + let tracked_op_qubits: Vec = (0..num_data).collect(); + let builder = InfluenceBuilder::new(&circuit).with_z(&tracked_op_qubits); let influence_map = builder.build(); let ( num_loc, num_det, - num_log, + num_dem_outputs, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, det_data_z, - log_off_x, - log_data_x, - log_off_y, - log_data_y, - log_off_z, - log_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ) = influence_map.export_csr(); let gpu_map = GpuInfluenceMapData::from_csr( - num_loc, num_det, num_log, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, - det_data_z, log_off_x, log_data_x, log_off_y, log_data_y, log_off_z, log_data_z, + num_loc, + num_det, + num_dem_outputs, + det_off_x, + det_data_x, + det_off_y, + det_data_y, + det_off_z, + det_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ); // CPU - let noise = UniformNoiseModel::depolarizing(p_error); - let mut cpu_sampler = NoisySampler::new(&influence_map, noise, seed); + let probs2 = vec![p_error; influence_map.locations.len()]; + let cpu_sampler = DemSampler::from_influence_map(&influence_map, &probs2); let cpu_start = Instant::now(); - let _ = cpu_sampler.sample(num_shots as usize); + let _ = cpu_sampler.sample_statistics(num_shots as usize, seed); let cpu_time = cpu_start.elapsed(); // GPU diff --git a/crates/pecos-gpu-sims/examples/full_pipeline_example.rs b/crates/pecos-gpu-sims/examples/full_pipeline_example.rs index 519d00e99..8cdcb25c1 100644 --- a/crates/pecos-gpu-sims/examples/full_pipeline_example.rs +++ b/crates/pecos-gpu-sims/examples/full_pipeline_example.rs @@ -83,8 +83,8 @@ fn main() { let circuit = build_repetition_code_circuit(2); println!(" Circuit built: {} gates", circuit.gate_count()); - // Build influence map with logical Z (sensitive to X errors) - let builder = InfluenceBuilder::new(&circuit).with_logical_z(vec![0, 1, 2]); + // Build influence map with a tracked Z operator (sensitive to X errors) + let builder = InfluenceBuilder::new(&circuit).with_z(&[0, 1, 2]); let influence_map = builder.build(); println!(" Locations: {}", influence_map.locations.len()); @@ -95,41 +95,41 @@ fn main() { let ( num_locations, num_detectors, - num_logicals, + num_dem_outputs, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, det_data_z, - log_off_x, - log_data_x, - log_off_y, - log_data_y, - log_off_z, - log_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ) = influence_map.export_csr(); println!( - " Exported CSR: {num_locations} locations, {num_detectors} detectors, {num_logicals} logicals" + " Exported CSR: {num_locations} locations, {num_detectors} detectors, {num_dem_outputs} DEM outputs" ); let gpu_map = GpuInfluenceMapData::from_csr( num_locations, num_detectors, - num_logicals, + num_dem_outputs, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, det_data_z, - log_off_x, - log_data_x, - log_off_y, - log_data_y, - log_off_z, - log_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ); // Sample with GPU @@ -139,15 +139,15 @@ fn main() { let p_error = 0.001; // 0.1% error rate let result = sampler.sample_uniform(num_shots, p_error); - let logical_errors = result.count_logical_errors(); + let logical_error_count = result.count_logical_errors(); #[allow(clippy::cast_precision_loss)] // rate calculation - let error_rate = logical_errors as f64 / f64::from(num_shots); + let logical_error_rate = logical_error_count as f64 / f64::from(num_shots); println!( " GPU Sampling: {} shots, p={}, logical error rate: {:.4}%", num_shots, p_error, - error_rate * 100.0 + logical_error_rate * 100.0 ); // ========================================================================= @@ -158,8 +158,8 @@ fn main() { let circuit = build_surface_code_plaquette(3); println!(" Circuit built: {} gates", circuit.gate_count()); - // Build influence map with logical X (sensitive to Z errors on this plaquette) - let builder = InfluenceBuilder::new(&circuit).with_logical_x(vec![0, 1, 2, 3]); + // Build influence map with a tracked X operator (sensitive to Z errors on this plaquette) + let builder = InfluenceBuilder::new(&circuit).with_x(&[0, 1, 2, 3]); let influence_map = builder.build(); println!(" Locations: {}", influence_map.locations.len()); @@ -169,51 +169,51 @@ fn main() { let ( num_locations, num_detectors, - num_logicals, + num_dem_outputs, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, det_data_z, - log_off_x, - log_data_x, - log_off_y, - log_data_y, - log_off_z, - log_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ) = influence_map.export_csr(); let gpu_map = GpuInfluenceMapData::from_csr( num_locations, num_detectors, - num_logicals, + num_dem_outputs, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, det_data_z, - log_off_x, - log_data_x, - log_off_y, - log_data_y, - log_off_z, - log_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ); let mut sampler = GpuInfluenceSampler::new(&gpu_map, 42).expect("Failed to create GPU sampler"); let result = sampler.sample_uniform(num_shots, p_error); - let logical_errors = result.count_logical_errors(); + let logical_error_count = result.count_logical_errors(); #[allow(clippy::cast_precision_loss)] // rate calculation - let error_rate = logical_errors as f64 / f64::from(num_shots); + let logical_error_rate = logical_error_count as f64 / f64::from(num_shots); println!( " GPU Sampling: {} shots, p={}, logical error rate: {:.4}%", num_shots, p_error, - error_rate * 100.0 + logical_error_rate * 100.0 ); // ========================================================================= @@ -223,43 +223,43 @@ fn main() { for num_rounds in [1, 2, 4, 8] { let circuit = build_repetition_code_circuit(num_rounds); - let builder = InfluenceBuilder::new(&circuit).with_logical_z(vec![0, 1, 2]); + let builder = InfluenceBuilder::new(&circuit).with_z(&[0, 1, 2]); let influence_map = builder.build(); let ( num_locations, num_detectors, - num_logicals, + num_dem_outputs, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, det_data_z, - log_off_x, - log_data_x, - log_off_y, - log_data_y, - log_off_z, - log_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ) = influence_map.export_csr(); let gpu_map = GpuInfluenceMapData::from_csr( num_locations, num_detectors, - num_logicals, + num_dem_outputs, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, det_data_z, - log_off_x, - log_data_x, - log_off_y, - log_data_y, - log_off_z, - log_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ); let mut sampler = @@ -269,14 +269,14 @@ fn main() { let result = sampler.sample_uniform(100_000, 0.001); let elapsed = start.elapsed(); - let logical_errors = result.count_logical_errors(); + let logical_error_count = result.count_logical_errors(); println!( - " {} rounds: {} locations, {} detectors, {} logical errors, {:.2}ms", + " {} rounds: {} locations, {} detectors, {} logical error shots, {:.2}ms", num_rounds, num_locations, num_detectors, - logical_errors, + logical_error_count, elapsed.as_secs_f64() * 1000.0 ); } diff --git a/crates/pecos-gpu-sims/examples/pipeline_benchmark.rs b/crates/pecos-gpu-sims/examples/pipeline_benchmark.rs index 387ba372f..87bc7180e 100644 --- a/crates/pecos-gpu-sims/examples/pipeline_benchmark.rs +++ b/crates/pecos-gpu-sims/examples/pipeline_benchmark.rs @@ -9,7 +9,7 @@ use pecos_gpu_sims::{GpuInfluenceMapData, GpuInfluenceSampler}; use pecos_qec::fault_tolerance::InfluenceBuilder; -use pecos_qec::fault_tolerance::noisy_sampler::{NoisySampler, UniformNoiseModel}; +use pecos_qec::fault_tolerance::dem_builder::DemSampler; use pecos_quantum::DagCircuit; use std::time::{Duration, Instant}; @@ -127,8 +127,8 @@ struct BenchmarkResult { build_time: Duration, cpu_time: Duration, gpu_time: Duration, - _cpu_logical_errors: usize, - _gpu_logical_errors: usize, + _cpu_logical_error_count: usize, + _gpu_logical_error_count: usize, } impl BenchmarkResult { @@ -150,14 +150,14 @@ impl BenchmarkResult { fn benchmark_circuit( name: &str, circuit: &DagCircuit, - logical_qubits: Vec, + tracked_op_qubits: &[usize], num_shots: u32, p_error: f64, seed: u64, ) -> BenchmarkResult { // Build influence map (common to both pipelines) let build_start = Instant::now(); - let builder = InfluenceBuilder::new(circuit).with_logical_z(logical_qubits); + let builder = InfluenceBuilder::new(circuit).with_z(tracked_op_qubits); let influence_map = builder.build(); let build_time = build_start.elapsed(); @@ -165,37 +165,50 @@ fn benchmark_circuit( let num_detectors = influence_map.detectors.len(); // CPU sampling - let noise = UniformNoiseModel::depolarizing(p_error); - let mut cpu_sampler = NoisySampler::new(&influence_map, noise, seed); + let probs = vec![p_error; num_locations]; + let cpu_sampler = DemSampler::from_influence_map(&influence_map, &probs); let cpu_start = Instant::now(); - let cpu_results = cpu_sampler.sample(num_shots as usize); + let cpu_stats = cpu_sampler.sample_statistics(num_shots as usize, seed); let cpu_time = cpu_start.elapsed(); - let cpu_logical_errors = cpu_results.iter().filter(|r| r.has_logical_error()).count(); + let cpu_logical_error_count = cpu_stats.logical_error_count; // GPU sampling let ( num_loc, num_det, - num_log, + num_dem_outputs, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, det_data_z, - log_off_x, - log_data_x, - log_off_y, - log_data_y, - log_off_z, - log_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ) = influence_map.export_csr(); let gpu_map = GpuInfluenceMapData::from_csr( - num_loc, num_det, num_log, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, - det_data_z, log_off_x, log_data_x, log_off_y, log_data_y, log_off_z, log_data_z, + num_loc, + num_det, + num_dem_outputs, + det_off_x, + det_data_x, + det_off_y, + det_data_y, + det_off_z, + det_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ); let mut gpu_sampler = @@ -208,7 +221,7 @@ fn benchmark_circuit( let gpu_result = gpu_sampler.sample_uniform(num_shots, p_error); let gpu_time = gpu_start.elapsed(); - let gpu_logical_errors = gpu_result.count_logical_errors(); + let gpu_logical_error_count = gpu_result.count_logical_errors(); BenchmarkResult { name: name.to_string(), @@ -218,8 +231,8 @@ fn benchmark_circuit( build_time, cpu_time, gpu_time, - _cpu_logical_errors: cpu_logical_errors, - _gpu_logical_errors: gpu_logical_errors, + _cpu_logical_error_count: cpu_logical_error_count, + _gpu_logical_error_count: gpu_logical_error_count, } } @@ -283,10 +296,17 @@ fn main() { for (num_data, num_rounds) in [(3, 2), (5, 3), (7, 4), (9, 5), (11, 6), (15, 8)] { let circuit = build_repetition_code(num_data, num_rounds); - let logical_qubits: Vec = (0..num_data).collect(); + let tracked_op_qubits: Vec = (0..num_data).collect(); let name = format!("rep_d{num_data}r{num_rounds}"); - let result = benchmark_circuit(&name, &circuit, logical_qubits, num_shots, p_error, seed); + let result = benchmark_circuit( + &name, + &circuit, + &tracked_op_qubits, + num_shots, + p_error, + seed, + ); results.push(result); } @@ -298,7 +318,7 @@ fn main() { println!("\nTest 2: Fixed Circuit (rep_d7r4) - Varying Shots\n"); let circuit = build_repetition_code(7, 4); - let logical_qubits: Vec = (0..7).collect(); + let tracked_op_qubits: Vec = (0..7).collect(); let mut shot_results = Vec::new(); @@ -307,7 +327,7 @@ fn main() { let result = benchmark_circuit( &name, &circuit, - logical_qubits.clone(), + &tracked_op_qubits, num_shots, p_error, seed, @@ -328,10 +348,17 @@ fn main() { for (distance, rounds) in [(3, 2), (4, 2), (5, 3), (6, 3), (7, 4)] { let circuit = build_surface_code_grid(distance, rounds); let num_data = distance * distance; - let logical_qubits: Vec = (0..num_data).collect(); + let tracked_op_qubits: Vec = (0..num_data).collect(); let name = format!("surf_d{distance}r{rounds}"); - let result = benchmark_circuit(&name, &circuit, logical_qubits, num_shots, p_error, seed); + let result = benchmark_circuit( + &name, + &circuit, + &tracked_op_qubits, + num_shots, + p_error, + seed, + ); surface_results.push(result); } diff --git a/crates/pecos-gpu-sims/examples/profile_samplers.rs b/crates/pecos-gpu-sims/examples/profile_samplers.rs index 54d979fc0..ace061419 100644 --- a/crates/pecos-gpu-sims/examples/profile_samplers.rs +++ b/crates/pecos-gpu-sims/examples/profile_samplers.rs @@ -5,9 +5,7 @@ use bytemuck::{Pod, Zeroable}; use pecos_gpu_sims::GpuInfluenceMapData; use pecos_qec::fault_tolerance::InfluenceBuilder; -use pecos_qec::fault_tolerance::noisy_sampler::{ - FastNoisySampler, NoisySampler, UniformNoiseModel, -}; +use pecos_qec::fault_tolerance::dem_builder::DemSampler; use pecos_quantum::DagCircuit; use pecos_random::PecosRng; use std::time::Instant; @@ -74,19 +72,18 @@ fn build_surface_code_grid(distance: usize, num_rounds: usize) -> DagCircuit { dag } -/// Profile the CPU sampler with detailed timing +/// Profile the CPU `DemSampler` with detailed timing fn profile_cpu_sampler( influence_map: &pecos_qec::fault_tolerance::DagFaultInfluenceMap, p_error: f64, seed: u64, num_shots: usize, ) -> CpuProfile { - let noise = UniformNoiseModel::depolarizing(p_error); - let mut sampler = NoisySampler::new(influence_map, noise, seed); + let probs = vec![p_error; influence_map.locations.len()]; + let sampler = DemSampler::from_influence_map(influence_map, &probs); - // Time the actual sampling let start = Instant::now(); - let _results = sampler.sample(num_shots); + let _stats = sampler.sample_statistics(num_shots, seed); let total_time = start.elapsed(); CpuProfile { @@ -103,27 +100,6 @@ struct CpuProfile { locations: usize, } -/// Profile the optimized `FastNoisySampler` -fn profile_fast_cpu_sampler( - influence_map: &pecos_qec::fault_tolerance::DagFaultInfluenceMap, - p_error: f64, - seed: u64, - num_shots: usize, -) -> CpuProfile { - let mut sampler = FastNoisySampler::new(influence_map, p_error, seed); - - // Time the actual sampling - let start = Instant::now(); - let _results = sampler.sample(num_shots); - let total_time = start.elapsed(); - - CpuProfile { - total_ms: total_time.as_secs_f64() * 1000.0, - shots: num_shots, - locations: influence_map.locations.len(), - } -} - /// Parameters for the sampling shader #[repr(C)] #[derive(Copy, Clone, Debug, Pod, Zeroable)] @@ -131,10 +107,10 @@ struct SamplerParams { num_locations: u32, num_shots: u32, num_detectors: u32, - num_logicals: u32, + num_dem_outputs: u32, p_error_threshold: u32, detector_words: u32, - logical_words: u32, + dem_output_words: u32, _padding: u32, } @@ -188,12 +164,12 @@ fn profile_gpu_sampler( let detector_data_y_buffer = create_buffer(&gpu_map.detector_data_y, "DetDataY"); let detector_offsets_z_buffer = create_buffer(&gpu_map.detector_offsets_z, "DetOffZ"); let detector_data_z_buffer = create_buffer(&gpu_map.detector_data_z, "DetDataZ"); - let logical_offsets_x_buffer = create_buffer(&gpu_map.logical_offsets_x, "LogOffX"); - let logical_data_x_buffer = create_buffer(&gpu_map.logical_data_x, "LogDataX"); - let logical_offsets_y_buffer = create_buffer(&gpu_map.logical_offsets_y, "LogOffY"); - let logical_data_y_buffer = create_buffer(&gpu_map.logical_data_y, "LogDataY"); - let logical_offsets_z_buffer = create_buffer(&gpu_map.logical_offsets_z, "LogOffZ"); - let logical_data_z_buffer = create_buffer(&gpu_map.logical_data_z, "LogDataZ"); + let dem_output_offsets_x_buffer = create_buffer(&gpu_map.dem_output_offsets_x, "DemOutOffX"); + let dem_output_data_x_buffer = create_buffer(&gpu_map.dem_output_data_x, "DemOutDataX"); + let dem_output_offsets_y_buffer = create_buffer(&gpu_map.dem_output_offsets_y, "DemOutOffY"); + let dem_output_data_y_buffer = create_buffer(&gpu_map.dem_output_data_y, "DemOutDataY"); + let dem_output_offsets_z_buffer = create_buffer(&gpu_map.dem_output_offsets_z, "DemOutOffZ"); + let dem_output_data_z_buffer = create_buffer(&gpu_map.dem_output_data_z, "DemOutDataZ"); let upload_map_time = upload_map_start.elapsed(); // Phase 3: Create shader and pipeline (done once) @@ -245,7 +221,7 @@ fn profile_gpu_sampler( // Phase 4: Create params buffer let params_start = Instant::now(); let detector_words = gpu_map.num_detectors.div_ceil(32).max(1); - let logical_words = gpu_map.num_logicals.div_ceil(32).max(1); + let dem_output_words = gpu_map.num_dem_outputs.div_ceil(32).max(1); #[allow(clippy::cast_sign_loss, clippy::cast_possible_truncation)] // probability in [0,1] maps to [0, u32::MAX] let p_threshold = (p_error * f64::from(u32::MAX)) as u32; @@ -253,10 +229,10 @@ fn profile_gpu_sampler( num_locations: gpu_map.num_locations, num_shots, num_detectors: gpu_map.num_detectors, - num_logicals: gpu_map.num_logicals, + num_dem_outputs: gpu_map.num_dem_outputs, p_error_threshold: p_threshold, detector_words, - logical_words, + dem_output_words, _padding: 0, }; let params_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor { @@ -282,7 +258,7 @@ fn profile_gpu_sampler( // Phase 6: Create output buffers let output_start = Instant::now(); let detector_output_size = (num_shots as usize * detector_words as usize * 4) as u64; - let logical_output_size = (num_shots as usize * logical_words as usize * 4) as u64; + let dem_output_size = (num_shots as usize * dem_output_words as usize * 4) as u64; let detector_output_buffer = device.create_buffer(&wgpu::BufferDescriptor { label: Some("Detector Output"), @@ -291,9 +267,9 @@ fn profile_gpu_sampler( mapped_at_creation: false, }); - let logical_output_buffer = device.create_buffer(&wgpu::BufferDescriptor { - label: Some("Logical Output"), - size: logical_output_size.max(4), + let dem_output_buffer = device.create_buffer(&wgpu::BufferDescriptor { + label: Some("DEM Output"), + size: dem_output_size.max(4), usage: wgpu::BufferUsages::STORAGE | wgpu::BufferUsages::COPY_SRC, mapped_at_creation: false, }); @@ -335,27 +311,27 @@ fn profile_gpu_sampler( }, wgpu::BindGroupEntry { binding: 7, - resource: logical_offsets_x_buffer.as_entire_binding(), + resource: dem_output_offsets_x_buffer.as_entire_binding(), }, wgpu::BindGroupEntry { binding: 8, - resource: logical_data_x_buffer.as_entire_binding(), + resource: dem_output_data_x_buffer.as_entire_binding(), }, wgpu::BindGroupEntry { binding: 9, - resource: logical_offsets_y_buffer.as_entire_binding(), + resource: dem_output_offsets_y_buffer.as_entire_binding(), }, wgpu::BindGroupEntry { binding: 10, - resource: logical_data_y_buffer.as_entire_binding(), + resource: dem_output_data_y_buffer.as_entire_binding(), }, wgpu::BindGroupEntry { binding: 11, - resource: logical_offsets_z_buffer.as_entire_binding(), + resource: dem_output_offsets_z_buffer.as_entire_binding(), }, wgpu::BindGroupEntry { binding: 12, - resource: logical_data_z_buffer.as_entire_binding(), + resource: dem_output_data_z_buffer.as_entire_binding(), }, wgpu::BindGroupEntry { binding: 13, @@ -367,7 +343,7 @@ fn profile_gpu_sampler( }, wgpu::BindGroupEntry { binding: 15, - resource: logical_output_buffer.as_entire_binding(), + resource: dem_output_buffer.as_entire_binding(), }, ], }); @@ -404,9 +380,9 @@ fn profile_gpu_sampler( usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ, mapped_at_creation: false, }); - let logical_staging = device.create_buffer(&wgpu::BufferDescriptor { - label: Some("Logical Staging"), - size: logical_output_size.max(4), + let dem_output_staging = device.create_buffer(&wgpu::BufferDescriptor { + label: Some("DEM Output Staging"), + size: dem_output_size.max(4), usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ, mapped_at_creation: false, }); @@ -420,11 +396,11 @@ fn profile_gpu_sampler( detector_output_size.max(4), ); encoder.copy_buffer_to_buffer( - &logical_output_buffer, + &dem_output_buffer, 0, - &logical_staging, + &dem_output_staging, 0, - logical_output_size.max(4), + dem_output_size.max(4), ); queue.submit(std::iter::once(encoder.finish())); @@ -435,9 +411,9 @@ fn profile_gpu_sampler( tx1.send(result).unwrap(); }); - let log_slice = logical_staging.slice(..); + let dem_output_slice = dem_output_staging.slice(..); let (tx2, rx2) = std::sync::mpsc::channel(); - log_slice.map_async(wgpu::MapMode::Read, move |result| { + dem_output_slice.map_async(wgpu::MapMode::Read, move |result| { tx2.send(result).unwrap(); }); @@ -450,9 +426,9 @@ fn profile_gpu_sampler( let _det_results: Vec = bytemuck::cast_slice(&det_data).to_vec(); drop(det_data); - let log_data = log_slice.get_mapped_range(); - let _log_results: Vec = bytemuck::cast_slice(&log_data).to_vec(); - drop(log_data); + let dem_output_data = dem_output_slice.get_mapped_range(); + let _dem_output_results: Vec = bytemuck::cast_slice(&dem_output_data).to_vec(); + drop(dem_output_data); let read_time = read_start.elapsed(); @@ -471,7 +447,7 @@ fn profile_gpu_sampler( #[allow(clippy::cast_possible_truncation)] // 64-bit target detector_output_bytes: detector_output_size as usize, #[allow(clippy::cast_possible_truncation)] // 64-bit target - logical_output_bytes: logical_output_size as usize, + dem_output_bytes: dem_output_size as usize, } } @@ -489,7 +465,7 @@ struct GpuProfile { #[allow(dead_code)] shots: usize, detector_output_bytes: usize, - logical_output_bytes: usize, + dem_output_bytes: usize, } impl GpuProfile { @@ -536,8 +512,8 @@ fn main() { let num_data = distance * distance; // Build influence map - let logical_qubits: Vec = (0..num_data).collect(); - let builder = InfluenceBuilder::new(&circuit).with_logical_z(logical_qubits); + let tracked_op_qubits: Vec = (0..num_data).collect(); + let builder = InfluenceBuilder::new(&circuit).with_z(&tracked_op_qubits); let influence_map = builder.build(); let num_locations = influence_map.locations.len(); @@ -545,24 +521,37 @@ fn main() { let ( num_loc, num_det, - num_log, + num_dem_outputs, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, det_data_z, - log_off_x, - log_data_x, - log_off_y, - log_data_y, - log_off_z, - log_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ) = influence_map.export_csr(); let gpu_map = GpuInfluenceMapData::from_csr( - num_loc, num_det, num_log, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, - det_data_z, log_off_x, log_data_x, log_off_y, log_data_y, log_off_z, log_data_z, + num_loc, + num_det, + num_dem_outputs, + det_off_x, + det_data_x, + det_off_y, + det_data_y, + det_off_z, + det_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ); println!( @@ -570,9 +559,9 @@ fn main() { ); println!("{:-<70}", ""); - // CPU profile (original) + // CPU profile (DemSampler) let cpu = profile_cpu_sampler(&influence_map, p_error, seed, num_shots as usize); - println!("\nCPU Pipeline (Original NoisySampler):"); + println!("\nCPU Pipeline (DemSampler):"); println!(" Total time: {:>10.2} ms", cpu.total_ms); println!( " Per-shot: {:>10.2} us", @@ -583,21 +572,6 @@ fn main() { cpu.shots as f64 / cpu.total_ms / 1000.0 ); - // CPU profile (fast/optimized) - let cpu_fast = profile_fast_cpu_sampler(&influence_map, p_error, seed, num_shots as usize); - println!("\nCPU Pipeline (FastNoisySampler - PecosRng + Sparse):"); - println!(" Total time: {:>10.2} ms", cpu_fast.total_ms); - println!( - " Per-shot: {:>10.2} us", - cpu_fast.total_ms * 1000.0 / cpu_fast.shots as f64 - ); - println!( - " Throughput: {:>10.3} M shots/sec", - cpu_fast.shots as f64 / cpu_fast.total_ms / 1000.0 - ); - let cpu_speedup = cpu.total_ms / cpu_fast.total_ms; - println!(" Speedup vs original: {cpu_speedup:>10.2}x"); - // GPU profile let gpu = profile_gpu_sampler(&gpu_map, p_error, seed, num_shots); println!("\nGPU Pipeline:"); @@ -617,22 +591,17 @@ fn main() { println!(" Subtotal (per-call): {:>10.2} ms", gpu.per_sample_ms()); println!(" Total: {:>10.2} ms", gpu.total_ms()); println!( - " Output size: {:>10.2} KB (det) + {:.2} KB (log)", + " Output size: {:>10.2} KB (det) + {:.2} KB (DEM out)", gpu.detector_output_bytes as f64 / 1024.0, - gpu.logical_output_bytes as f64 / 1024.0 + gpu.dem_output_bytes as f64 / 1024.0 ); println!("\nComparison:"); - println!(" CPU (original): {:>10.2} ms", cpu.total_ms); - println!(" CPU (fast): {:>10.2} ms", cpu_fast.total_ms); + println!(" CPU (DemSampler): {:>10.2} ms", cpu.total_ms); println!(" GPU total (with init): {:>10.2} ms", gpu.total_ms()); println!(" GPU per-call only: {:>10.2} ms", gpu.per_sample_ms()); - let speedup_fast_vs_orig = cpu.total_ms / cpu_fast.total_ms; - let speedup_gpu_vs_orig = cpu.total_ms / gpu.per_sample_ms(); - let speedup_gpu_vs_fast = cpu_fast.total_ms / gpu.per_sample_ms(); - println!(" Fast CPU vs Original: {speedup_fast_vs_orig:>10.1}x"); - println!(" GPU vs Original CPU: {speedup_gpu_vs_orig:>10.1}x"); - println!(" GPU vs Fast CPU: {speedup_gpu_vs_fast:>10.1}x"); + let speedup_gpu_vs_cpu = cpu.total_ms / gpu.per_sample_ms(); + println!(" GPU vs CPU: {speedup_gpu_vs_cpu:>10.1}x"); println!("\n"); } diff --git a/crates/pecos-gpu-sims/src/gpu.rs b/crates/pecos-gpu-sims/src/gpu.rs index b31327751..3e092b6ee 100644 --- a/crates/pecos-gpu-sims/src/gpu.rs +++ b/crates/pecos-gpu-sims/src/gpu.rs @@ -1552,6 +1552,10 @@ impl QuantumSimulator for GpuStateVec32 { .write_buffer(&self.state_buffer, 0, bytemuck::cast_slice(&initial_state)); self } + + fn num_qubits(&self) -> usize { + self.num_qubits as usize + } } // Trait implementations queue gates for batched dispatch. diff --git a/crates/pecos-gpu-sims/src/gpu64.rs b/crates/pecos-gpu-sims/src/gpu64.rs index 81387dd0d..ec9e887e4 100644 --- a/crates/pecos-gpu-sims/src/gpu64.rs +++ b/crates/pecos-gpu-sims/src/gpu64.rs @@ -1245,6 +1245,10 @@ impl QuantumSimulator for GpuStateVec64 { self.reset(); self } + + fn num_qubits(&self) -> usize { + self.num_qubits as usize + } } #[allow(clippy::cast_possible_truncation)] diff --git a/crates/pecos-gpu-sims/src/gpu_auto.rs b/crates/pecos-gpu-sims/src/gpu_auto.rs index 02ba8ae48..eba201c96 100644 --- a/crates/pecos-gpu-sims/src/gpu_auto.rs +++ b/crates/pecos-gpu-sims/src/gpu_auto.rs @@ -71,6 +71,13 @@ impl QuantumSimulator for GpuStateVecAuto { fn reset(&mut self) -> &mut Self { dispatch_mut!(self, reset()) } + + fn num_qubits(&self) -> usize { + match self { + Self::F64(s) => QuantumSimulator::num_qubits(s), + Self::F32(s) => QuantumSimulator::num_qubits(s), + } + } } impl CliffordGateable for GpuStateVecAuto { diff --git a/crates/pecos-gpu-sims/src/gpu_density_matrix.rs b/crates/pecos-gpu-sims/src/gpu_density_matrix.rs index a9d28593e..58bfa2472 100644 --- a/crates/pecos-gpu-sims/src/gpu_density_matrix.rs +++ b/crates/pecos-gpu-sims/src/gpu_density_matrix.rs @@ -539,6 +539,10 @@ impl QuantumSimulator for GpuDensityMatrix { self.state_vector.reset(); self } + + fn num_qubits(&self) -> usize { + self.num_physical_qubits + } } impl RngManageable for GpuDensityMatrix { diff --git a/crates/pecos-gpu-sims/src/gpu_influence_sampler.rs b/crates/pecos-gpu-sims/src/gpu_influence_sampler.rs index b550c22ad..b3d1024ba 100644 --- a/crates/pecos-gpu-sims/src/gpu_influence_sampler.rs +++ b/crates/pecos-gpu-sims/src/gpu_influence_sampler.rs @@ -11,14 +11,14 @@ use wgpu::util::DeviceExt; /// Influence map data for GPU sampling. /// /// Contains CSR (Compressed Sparse Row) arrays mapping fault locations -/// to their detector and logical influences for X, Y, and Z Pauli faults. +/// to their detector and DEM-output influences for X, Y, and Z Pauli faults. pub struct GpuInfluenceMapData { /// Number of fault locations. pub num_locations: u32, /// Number of detectors. pub num_detectors: u32, - /// Number of logicals. - pub num_logicals: u32, + /// Number of DEM `L` outputs. + pub num_dem_outputs: u32, // CSR arrays for detector influences /// Offsets for X detector influences: `offsets_x`[loc] to `offsets_x`[loc+1] @@ -34,19 +34,19 @@ pub struct GpuInfluenceMapData { /// Detector indices for Z faults. pub detector_data_z: Vec, - // CSR arrays for logical influences - /// Offsets for X logical influences. - pub logical_offsets_x: Vec, - /// Logical indices for X faults. - pub logical_data_x: Vec, - /// Offsets for Y logical influences. - pub logical_offsets_y: Vec, - /// Logical indices for Y faults. - pub logical_data_y: Vec, - /// Offsets for Z logical influences. - pub logical_offsets_z: Vec, - /// Logical indices for Z faults. - pub logical_data_z: Vec, + // CSR arrays for DEM-output influences + /// Offsets for X DEM-output influences. + pub dem_output_offsets_x: Vec, + /// DEM-output indices for X faults. + pub dem_output_data_x: Vec, + /// Offsets for Y DEM-output influences. + pub dem_output_offsets_y: Vec, + /// DEM-output indices for Y faults. + pub dem_output_data_y: Vec, + /// Offsets for Z DEM-output influences. + pub dem_output_offsets_z: Vec, + /// DEM-output indices for Z faults. + pub dem_output_data_z: Vec, } impl GpuInfluenceMapData { @@ -56,19 +56,19 @@ impl GpuInfluenceMapData { Self { num_locations: 0, num_detectors: 0, - num_logicals: 0, + num_dem_outputs: 0, detector_offsets_x: vec![0], detector_data_x: vec![], detector_offsets_y: vec![0], detector_data_y: vec![], detector_offsets_z: vec![0], detector_data_z: vec![], - logical_offsets_x: vec![0], - logical_data_x: vec![], - logical_offsets_y: vec![0], - logical_data_y: vec![], - logical_offsets_z: vec![0], - logical_data_z: vec![], + dem_output_offsets_x: vec![0], + dem_output_data_x: vec![], + dem_output_offsets_y: vec![0], + dem_output_data_y: vec![], + dem_output_offsets_z: vec![0], + dem_output_data_z: vec![], } } @@ -78,36 +78,36 @@ impl GpuInfluenceMapData { pub fn from_csr( num_locations: u32, num_detectors: u32, - num_logicals: u32, + num_dem_outputs: u32, detector_offsets_x: Vec, detector_data_x: Vec, detector_offsets_y: Vec, detector_data_y: Vec, detector_offsets_z: Vec, detector_data_z: Vec, - logical_offsets_x: Vec, - logical_data_x: Vec, - logical_offsets_y: Vec, - logical_data_y: Vec, - logical_offsets_z: Vec, - logical_data_z: Vec, + dem_output_offsets_x: Vec, + dem_output_data_x: Vec, + dem_output_offsets_y: Vec, + dem_output_data_y: Vec, + dem_output_offsets_z: Vec, + dem_output_data_z: Vec, ) -> Self { Self { num_locations, num_detectors, - num_logicals, + num_dem_outputs, detector_offsets_x, detector_data_x, detector_offsets_y, detector_data_y, detector_offsets_z, detector_data_z, - logical_offsets_x, - logical_data_x, - logical_offsets_y, - logical_data_y, - logical_offsets_z, - logical_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, } } } @@ -119,10 +119,10 @@ struct SamplerParams { num_locations: u32, num_shots: u32, num_detectors: u32, - num_logicals: u32, + num_dem_outputs: u32, p_error_threshold: u32, detector_words: u32, - logical_words: u32, + dem_output_words: u32, _padding: u32, } @@ -133,7 +133,7 @@ struct SamplerParams { pub struct GpuInfluenceSampler { num_locations: u32, num_detectors: u32, - num_logicals: u32, + num_dem_outputs: u32, device: wgpu::Device, queue: wgpu::Queue, @@ -147,12 +147,12 @@ pub struct GpuInfluenceSampler { detector_data_y_buffer: wgpu::Buffer, detector_offsets_z_buffer: wgpu::Buffer, detector_data_z_buffer: wgpu::Buffer, - logical_offsets_x_buffer: wgpu::Buffer, - logical_data_x_buffer: wgpu::Buffer, - logical_offsets_y_buffer: wgpu::Buffer, - logical_data_y_buffer: wgpu::Buffer, - logical_offsets_z_buffer: wgpu::Buffer, - logical_data_z_buffer: wgpu::Buffer, + dem_output_offsets_x_buffer: wgpu::Buffer, + dem_output_data_x_buffer: wgpu::Buffer, + dem_output_offsets_y_buffer: wgpu::Buffer, + dem_output_data_y_buffer: wgpu::Buffer, + dem_output_offsets_z_buffer: wgpu::Buffer, + dem_output_data_z_buffer: wgpu::Buffer, bind_group_layout: wgpu::BindGroupLayout, pipeline: wgpu::ComputePipeline, @@ -199,22 +199,22 @@ impl GpuInfluenceSampler { let detector_data_y_buffer = create_buffer(&map.detector_data_y, "DetDataY"); let detector_offsets_z_buffer = create_buffer(&map.detector_offsets_z, "DetOffZ"); let detector_data_z_buffer = create_buffer(&map.detector_data_z, "DetDataZ"); - let logical_offsets_x_buffer = create_buffer(&map.logical_offsets_x, "LogOffX"); - let logical_data_x_buffer = create_buffer(&map.logical_data_x, "LogDataX"); - let logical_offsets_y_buffer = create_buffer(&map.logical_offsets_y, "LogOffY"); - let logical_data_y_buffer = create_buffer(&map.logical_data_y, "LogDataY"); - let logical_offsets_z_buffer = create_buffer(&map.logical_offsets_z, "LogOffZ"); - let logical_data_z_buffer = create_buffer(&map.logical_data_z, "LogDataZ"); + let dem_output_offsets_x_buffer = create_buffer(&map.dem_output_offsets_x, "DemOutOffX"); + let dem_output_data_x_buffer = create_buffer(&map.dem_output_data_x, "DemOutDataX"); + let dem_output_offsets_y_buffer = create_buffer(&map.dem_output_offsets_y, "DemOutOffY"); + let dem_output_data_y_buffer = create_buffer(&map.dem_output_data_y, "DemOutDataY"); + let dem_output_offsets_z_buffer = create_buffer(&map.dem_output_offsets_z, "DemOutOffZ"); + let dem_output_data_z_buffer = create_buffer(&map.dem_output_data_z, "DemOutDataZ"); // Create params buffer let params = SamplerParams { num_locations: map.num_locations, num_shots: 0, num_detectors: map.num_detectors, - num_logicals: map.num_logicals, + num_dem_outputs: map.num_dem_outputs, p_error_threshold: 0, detector_words: 0, - logical_words: 0, + dem_output_words: 0, _padding: 0, }; let params_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor { @@ -419,7 +419,7 @@ impl GpuInfluenceSampler { Ok(Self { num_locations: map.num_locations, num_detectors: map.num_detectors, - num_logicals: map.num_logicals, + num_dem_outputs: map.num_dem_outputs, device, queue, params_buffer, @@ -429,12 +429,12 @@ impl GpuInfluenceSampler { detector_data_y_buffer, detector_offsets_z_buffer, detector_data_z_buffer, - logical_offsets_x_buffer, - logical_data_x_buffer, - logical_offsets_y_buffer, - logical_data_y_buffer, - logical_offsets_z_buffer, - logical_data_z_buffer, + dem_output_offsets_x_buffer, + dem_output_data_x_buffer, + dem_output_offsets_y_buffer, + dem_output_data_y_buffer, + dem_output_offsets_z_buffer, + dem_output_data_z_buffer, bind_group_layout, pipeline, rng: PecosRng::seed_from_u64(seed), @@ -444,7 +444,7 @@ impl GpuInfluenceSampler { /// Sample with uniform depolarizing noise. pub fn sample_uniform(&mut self, num_shots: u32, p_error: f64) -> GpuSamplingResult { let detector_words = self.num_detectors.div_ceil(32).max(1); - let logical_words = self.num_logicals.div_ceil(32).max(1); + let dem_output_words = self.num_dem_outputs.div_ceil(32).max(1); // Update params #[allow(clippy::cast_sign_loss, clippy::cast_possible_truncation)] @@ -454,10 +454,10 @@ impl GpuInfluenceSampler { num_locations: self.num_locations, num_shots, num_detectors: self.num_detectors, - num_logicals: self.num_logicals, + num_dem_outputs: self.num_dem_outputs, p_error_threshold: p_threshold, detector_words, - logical_words, + dem_output_words, _padding: 0, }; self.queue @@ -476,7 +476,7 @@ impl GpuInfluenceSampler { // Create output buffers - layout: [shot * words + word_idx] let detector_output_size = (num_shots as usize * detector_words as usize * 4) as u64; - let logical_output_size = (num_shots as usize * logical_words as usize * 4) as u64; + let dem_output_size = (num_shots as usize * dem_output_words as usize * 4) as u64; let detector_output_buffer = self.device.create_buffer(&wgpu::BufferDescriptor { label: Some("Detector Output"), @@ -485,9 +485,9 @@ impl GpuInfluenceSampler { mapped_at_creation: false, }); - let logical_output_buffer = self.device.create_buffer(&wgpu::BufferDescriptor { - label: Some("Logical Output"), - size: logical_output_size.max(4), + let dem_output_buffer = self.device.create_buffer(&wgpu::BufferDescriptor { + label: Some("DEM Output"), + size: dem_output_size.max(4), usage: wgpu::BufferUsages::STORAGE | wgpu::BufferUsages::COPY_SRC, mapped_at_creation: false, }); @@ -527,27 +527,27 @@ impl GpuInfluenceSampler { }, wgpu::BindGroupEntry { binding: 7, - resource: self.logical_offsets_x_buffer.as_entire_binding(), + resource: self.dem_output_offsets_x_buffer.as_entire_binding(), }, wgpu::BindGroupEntry { binding: 8, - resource: self.logical_data_x_buffer.as_entire_binding(), + resource: self.dem_output_data_x_buffer.as_entire_binding(), }, wgpu::BindGroupEntry { binding: 9, - resource: self.logical_offsets_y_buffer.as_entire_binding(), + resource: self.dem_output_offsets_y_buffer.as_entire_binding(), }, wgpu::BindGroupEntry { binding: 10, - resource: self.logical_data_y_buffer.as_entire_binding(), + resource: self.dem_output_data_y_buffer.as_entire_binding(), }, wgpu::BindGroupEntry { binding: 11, - resource: self.logical_offsets_z_buffer.as_entire_binding(), + resource: self.dem_output_offsets_z_buffer.as_entire_binding(), }, wgpu::BindGroupEntry { binding: 12, - resource: self.logical_data_z_buffer.as_entire_binding(), + resource: self.dem_output_data_z_buffer.as_entire_binding(), }, wgpu::BindGroupEntry { binding: 13, @@ -559,7 +559,7 @@ impl GpuInfluenceSampler { }, wgpu::BindGroupEntry { binding: 15, - resource: logical_output_buffer.as_entire_binding(), + resource: dem_output_buffer.as_entire_binding(), }, ], }); @@ -591,20 +591,20 @@ impl GpuInfluenceSampler { num_shots as usize, detector_words as usize, ); - let logical_flips = self.read_output( - &logical_output_buffer, + let dem_output_flips = self.read_output( + &dem_output_buffer, num_shots as usize, - logical_words as usize, + dem_output_words as usize, ); GpuSamplingResult { num_shots: num_shots as usize, detector_flips, - logical_flips, + dem_output_flips, num_detectors: self.num_detectors as usize, - num_logicals: self.num_logicals as usize, + num_dem_outputs: self.num_dem_outputs as usize, detector_words: detector_words as usize, - logical_words: logical_words as usize, + dem_output_words: dem_output_words as usize, } } @@ -652,42 +652,61 @@ pub struct GpuSamplingResult { pub num_shots: usize, /// Flat array: [shot * `detector_words` + word] pub detector_flips: Vec, - /// Flat array: [shot * `logical_words` + word] - pub logical_flips: Vec, + /// Flat array: [shot * `dem_output_words` + word] + pub dem_output_flips: Vec, pub num_detectors: usize, - pub num_logicals: usize, + pub num_dem_outputs: usize, pub detector_words: usize, - pub logical_words: usize, + pub dem_output_words: usize, } impl GpuSamplingResult { + fn logical_word_mask(&self, word_idx: usize) -> u32 { + if self.num_dem_outputs == 0 || word_idx >= self.dem_output_words { + return 0; + } + let remaining = self.num_dem_outputs.saturating_sub(word_idx * 32); + if remaining >= 32 { + u32::MAX + } else if remaining == 0 { + 0 + } else { + (1u32 << remaining) - 1 + } + } + /// Count shots with any logical error. #[must_use] pub fn count_logical_errors(&self) -> usize { - if self.num_logicals == 0 { + if self.num_dem_outputs == 0 { return 0; } let mut count = 0; for shot in 0..self.num_shots { - let base = shot * self.logical_words; - let has_error = (0..self.logical_words) - .any(|w| self.logical_flips.get(base + w).copied().unwrap_or(0) != 0); - if has_error { + let base = shot * self.dem_output_words; + let has_flip = (0..self.dem_output_words).any(|w| { + let word = self.dem_output_flips.get(base + w).copied().unwrap_or(0); + (word & self.logical_word_mask(w)) != 0 + }); + if has_flip { count += 1; } } count } - /// Check if a specific shot has a logical error. + /// Check if a specific shot has any logical error. #[must_use] pub fn has_logical_error(&self, shot: usize) -> bool { - if shot >= self.num_shots || self.num_logicals == 0 { + if shot >= self.num_shots || self.num_dem_outputs == 0 { return false; } - let base = shot * self.logical_words; - (0..self.logical_words).any(|w| self.logical_flips.get(base + w).copied().unwrap_or(0) != 0) + let base = shot * self.dem_output_words; + (0..self.dem_output_words).any(|w| { + let word = self.dem_output_flips.get(base + w).copied().unwrap_or(0); + (word & self.logical_word_mask(w)) != 0 + }) } /// Get detector flip bits for a specific shot. diff --git a/crates/pecos-gpu-sims/src/gpu_pauli_prop.rs b/crates/pecos-gpu-sims/src/gpu_pauli_prop.rs index 067fb8b26..1c88807da 100644 --- a/crates/pecos-gpu-sims/src/gpu_pauli_prop.rs +++ b/crates/pecos-gpu-sims/src/gpu_pauli_prop.rs @@ -651,15 +651,15 @@ impl GpuPauliProp { /// Check if a Pauli string anticommutes with the accumulated faults. /// - /// This is used to check for logical errors: if the fault anticommutes - /// with a logical operator, it's a logical error. + /// This is used to check whether faults flip a tracked Pauli string: + /// an odd number of anticommutations means the tracked operator flips. /// /// # Arguments /// * `x_qubits` - Qubits with X in the Pauli string /// * `z_qubits` - Qubits with Z in the Pauli string /// /// # Returns - /// A vector of bools, one per shot, true if anticommutes (logical error). + /// A vector of bools, one per shot, true if the tracked Pauli string flips. pub fn check_anticommutation(&mut self, x_qubits: &[usize], z_qubits: &[usize]) -> Vec { self.sync(); @@ -674,7 +674,7 @@ impl GpuPauliProp { let mut anticom_count = 0u32; - // X in logical anticommutes with Z faults + // X in the tracked operator anticommutes with Z faults. for &q in x_qubits { let base = q * self.shot_words as usize; if (z_faults[base + word_idx] >> bit_idx) & 1 != 0 { @@ -682,7 +682,7 @@ impl GpuPauliProp { } } - // Z in logical anticommutes with X faults + // Z in the tracked operator anticommutes with X faults. for &q in z_qubits { let base = q * self.shot_words as usize; if (x_faults[base + word_idx] >> bit_idx) & 1 != 0 { @@ -885,11 +885,11 @@ mod tests { prop.inject_x_fault(0); prop.flush(); - // Check against Z logical on qubit 0 (should anticommute) + // Check against tracked Z on qubit 0 (should anticommute) let results = prop.check_anticommutation(&[], &[0]); assert!(results.iter().all(|&b| b)); // All shots: anticommutes - // Check against X logical on qubit 0 (should commute) + // Check against tracked X on qubit 0 (should commute) let results = prop.check_anticommutation(&[0], &[]); assert!(results.iter().all(|&b| !b)); // All shots: commutes } diff --git a/crates/pecos-gpu-sims/src/gpu_stab.rs b/crates/pecos-gpu-sims/src/gpu_stab.rs index 6013210d2..945d64d24 100644 --- a/crates/pecos-gpu-sims/src/gpu_stab.rs +++ b/crates/pecos-gpu-sims/src/gpu_stab.rs @@ -2464,6 +2464,10 @@ impl QuantumSimulator for GpuStab { self.initialize_state(); self } + + fn num_qubits(&self) -> usize { + self.num_qubits as usize + } } impl Debug for GpuStab { diff --git a/crates/pecos-gpu-sims/src/gpu_stab_multi.rs b/crates/pecos-gpu-sims/src/gpu_stab_multi.rs index 283ebf8ea..0c734a965 100644 --- a/crates/pecos-gpu-sims/src/gpu_stab_multi.rs +++ b/crates/pecos-gpu-sims/src/gpu_stab_multi.rs @@ -48,7 +48,7 @@ pub struct GpuStabMulti { #[allow(dead_code)] meas_data_buffer: wgpu::Buffer, meas_random_buffer: wgpu::Buffer, - meas_results_buffer: wgpu::Buffer, + meas_ids_buffer: wgpu::Buffer, meas_staging_buffer: wgpu::Buffer, meas_bind_group: wgpu::BindGroup, meas_find_pipeline: wgpu::ComputePipeline, @@ -228,7 +228,7 @@ impl GpuStabMulti { mapped_at_creation: false, }); - let meas_results_buffer = device.create_buffer(&wgpu::BufferDescriptor { + let meas_ids_buffer = device.create_buffer(&wgpu::BufferDescriptor { label: Some("Multi Measurement Results Buffer"), size: u64::from(shots_per_batch) * 4, usage: wgpu::BufferUsages::STORAGE @@ -506,7 +506,7 @@ impl GpuStabMulti { }, wgpu::BindGroupEntry { binding: 3, - resource: meas_results_buffer.as_entire_binding(), + resource: meas_ids_buffer.as_entire_binding(), }, ], }); @@ -602,7 +602,7 @@ impl GpuStabMulti { // GPU-side measurement meas_data_buffer, meas_random_buffer, - meas_results_buffer, + meas_ids_buffer, meas_staging_buffer, meas_bind_group, meas_find_pipeline, @@ -1427,7 +1427,7 @@ impl GpuStabMulti { // Copy this measurement's results to staging buffer encoder.copy_buffer_to_buffer( - &self.meas_results_buffer, + &self.meas_ids_buffer, 0, &self.meas_staging_buffer, 0, @@ -1576,7 +1576,7 @@ impl GpuStabMulti { } encoder.copy_buffer_to_buffer( - &self.meas_results_buffer, + &self.meas_ids_buffer, 0, &self.meas_staging_buffer, 0, diff --git a/crates/pecos-gpu-sims/src/influence_sampler_shader.wgsl b/crates/pecos-gpu-sims/src/influence_sampler_shader.wgsl index 7a290b759..1dbbc788d 100644 --- a/crates/pecos-gpu-sims/src/influence_sampler_shader.wgsl +++ b/crates/pecos-gpu-sims/src/influence_sampler_shader.wgsl @@ -16,10 +16,10 @@ struct Params { num_locations: u32, num_shots: u32, num_detectors: u32, - num_logicals: u32, + num_dem_outputs: u32, p_error_threshold: u32, // Fixed-point threshold (p * 0xFFFFFFFF) detector_words: u32, // ceil(num_detectors / 32) - logical_words: u32, // ceil(num_logicals / 32) + dem_output_words: u32, // ceil(num_dem_outputs / 32) _padding: u32, } @@ -33,22 +33,22 @@ struct Params { @group(0) @binding(5) var det_offsets_z: array; @group(0) @binding(6) var det_data_z: array; -// Logical influence CSR arrays -@group(0) @binding(7) var log_offsets_x: array; -@group(0) @binding(8) var log_data_x: array; -@group(0) @binding(9) var log_offsets_y: array; -@group(0) @binding(10) var log_data_y: array; -@group(0) @binding(11) var log_offsets_z: array; -@group(0) @binding(12) var log_data_z: array; +// DEM-output influence CSR arrays +@group(0) @binding(7) var dem_output_offsets_x: array; +@group(0) @binding(8) var dem_output_data_x: array; +@group(0) @binding(9) var dem_output_offsets_y: array; +@group(0) @binding(10) var dem_output_data_y: array; +@group(0) @binding(11) var dem_output_offsets_z: array; +@group(0) @binding(12) var dem_output_data_z: array; // Random seeds (one per shot) @group(0) @binding(13) var random_seeds: array; -// Output: detector and logical flips +// Output: detector and DEM-output flips // Layout: [shot * words + word_idx] - each shot has its own contiguous region // NO atomics needed since each shot is processed by exactly one thread @group(0) @binding(14) var detector_flips: array; -@group(0) @binding(15) var logical_flips: array; +@group(0) @binding(15) var dem_output_flips: array; // PCG-style hash function for deterministic randomness fn hash(seed: u32, loc: u32, extra: u32) -> u32 { @@ -71,12 +71,12 @@ fn xor_detector(shot_base: u32, det_idx: u32, detector_words: u32) { } } -fn xor_logical(shot_base: u32, log_idx: u32, logical_words: u32) { - let word = log_idx / 32u; - let bit = log_idx % 32u; - if (word < logical_words) { +fn xor_dem_output(shot_base: u32, dem_output_idx: u32, dem_output_words: u32) { + let word = dem_output_idx / 32u; + let bit = dem_output_idx % 32u; + if (word < dem_output_words) { let idx = shot_base + word; - logical_flips[idx] = logical_flips[idx] ^ (1u << bit); + dem_output_flips[idx] = dem_output_flips[idx] ^ (1u << bit); } } @@ -90,14 +90,14 @@ fn main(@builtin(global_invocation_id) global_id: vec3) { let seed = random_seeds[shot]; let det_base = shot * params.detector_words; - let log_base = shot * params.logical_words; + let dem_output_base = shot * params.dem_output_words; // Initialize this shot's output to zero for (var w = 0u; w < params.detector_words; w = w + 1u) { detector_flips[det_base + w] = 0u; } - for (var w = 0u; w < params.logical_words; w = w + 1u) { - logical_flips[log_base + w] = 0u; + for (var w = 0u; w < params.dem_output_words; w = w + 1u) { + dem_output_flips[dem_output_base + w] = 0u; } // Process ALL locations for this shot @@ -113,7 +113,7 @@ fn main(@builtin(global_invocation_id) global_id: vec3) { let rand_pauli = hash(seed, loc, 1u); let pauli = rand_pauli % 3u; - // Process detector and logical influences based on Pauli type + // Process detector and DEM-output influences based on Pauli type if (pauli == 0u) { // X fault - process detector influences let det_start = det_offsets_x[loc]; @@ -122,11 +122,11 @@ fn main(@builtin(global_invocation_id) global_id: vec3) { xor_detector(det_base, det_data_x[i], params.detector_words); } - // X fault - process logical influences - let log_start = log_offsets_x[loc]; - let log_end = log_offsets_x[loc + 1u]; - for (var i = log_start; i < log_end; i = i + 1u) { - xor_logical(log_base, log_data_x[i], params.logical_words); + // X fault - process DEM-output influences + let dem_output_start = dem_output_offsets_x[loc]; + let dem_output_end = dem_output_offsets_x[loc + 1u]; + for (var i = dem_output_start; i < dem_output_end; i = i + 1u) { + xor_dem_output(dem_output_base, dem_output_data_x[i], params.dem_output_words); } } else if (pauli == 1u) { // Y fault - process detector influences @@ -136,11 +136,11 @@ fn main(@builtin(global_invocation_id) global_id: vec3) { xor_detector(det_base, det_data_y[i], params.detector_words); } - // Y fault - process logical influences - let log_start = log_offsets_y[loc]; - let log_end = log_offsets_y[loc + 1u]; - for (var i = log_start; i < log_end; i = i + 1u) { - xor_logical(log_base, log_data_y[i], params.logical_words); + // Y fault - process DEM-output influences + let dem_output_start = dem_output_offsets_y[loc]; + let dem_output_end = dem_output_offsets_y[loc + 1u]; + for (var i = dem_output_start; i < dem_output_end; i = i + 1u) { + xor_dem_output(dem_output_base, dem_output_data_y[i], params.dem_output_words); } } else { // Z fault - process detector influences @@ -150,11 +150,11 @@ fn main(@builtin(global_invocation_id) global_id: vec3) { xor_detector(det_base, det_data_z[i], params.detector_words); } - // Z fault - process logical influences - let log_start = log_offsets_z[loc]; - let log_end = log_offsets_z[loc + 1u]; - for (var i = log_start; i < log_end; i = i + 1u) { - xor_logical(log_base, log_data_z[i], params.logical_words); + // Z fault - process DEM-output influences + let dem_output_start = dem_output_offsets_z[loc]; + let dem_output_end = dem_output_offsets_z[loc + 1u]; + for (var i = dem_output_start; i < dem_output_end; i = i + 1u) { + xor_dem_output(dem_output_base, dem_output_data_z[i], params.dem_output_words); } } } diff --git a/crates/pecos-gpu-sims/tests/influence_sampler_audit.rs b/crates/pecos-gpu-sims/tests/influence_sampler_audit.rs index 530d5b58d..6c6d2e0c5 100644 --- a/crates/pecos-gpu-sims/tests/influence_sampler_audit.rs +++ b/crates/pecos-gpu-sims/tests/influence_sampler_audit.rs @@ -9,59 +9,72 @@ //! //! Semantics: for each shot, each location has probability `p_error` of a //! fault. If a fault fires, a random Pauli (X/Y/Z, uniformly) is applied. -//! Each fault toggles a CSR-encoded set of detectors and logicals. +//! Each fault toggles a CSR-encoded set of detectors and DEM outputs. //! //! We don't have a CPU reference implementation to cross-check against. //! Instead, we use tight edge-case tests + distributional sanity checks. -use pecos_gpu_sims::{GpuInfluenceMapData, GpuInfluenceSampler}; +use pecos_gpu_sims::{GpuInfluenceMapData, GpuInfluenceSampler, GpuSamplingResult}; /// Build an influence map with `n_loc` locations, `n_det` detectors, and -/// `n_log` logicals, where: +/// `n_dem_outputs` DEM outputs, where: /// - X fault at location `k` toggles detector `k % n_det` -/// - Z fault at location `k` toggles logical `k % n_log` +/// - Z fault at location `k` toggles DEM output `k % n_dem_outputs` /// - Y fault at location `k` toggles both /// /// Written as three separate CSR tables (X, Y, Z each have a row per location). #[allow(clippy::cast_possible_truncation)] // CSR row offsets, n_loc bounded by test inputs (<= u32::MAX trivially) -fn simple_diagonal_map(n_loc: u32, n_det: u32, n_log: u32) -> GpuInfluenceMapData { +fn simple_diagonal_map(n_loc: u32, n_det: u32, n_dem_outputs: u32) -> GpuInfluenceMapData { let mut det_off_x = vec![0u32; (n_loc + 1) as usize]; let mut det_dat_x = Vec::::new(); let mut det_off_y = vec![0u32; (n_loc + 1) as usize]; let mut det_dat_y = Vec::::new(); let mut det_off_z = vec![0u32; (n_loc + 1) as usize]; let det_dat_z = Vec::::new(); - let mut log_off_x = vec![0u32; (n_loc + 1) as usize]; - let log_dat_x = Vec::::new(); - let mut log_off_y = vec![0u32; (n_loc + 1) as usize]; - let mut log_dat_y = Vec::::new(); - let mut log_off_z = vec![0u32; (n_loc + 1) as usize]; - let mut log_dat_z = Vec::::new(); + let mut dem_output_offsets_x = vec![0u32; (n_loc + 1) as usize]; + let dem_output_dat_x = Vec::::new(); + let mut dem_output_offsets_y = vec![0u32; (n_loc + 1) as usize]; + let mut dem_output_dat_y = Vec::::new(); + let mut dem_output_offsets_z = vec![0u32; (n_loc + 1) as usize]; + let mut dem_output_dat_z = Vec::::new(); for k in 0..n_loc { // X at k -> detector (k % n_det) det_dat_x.push(k % n_det); det_off_x[(k + 1) as usize] = det_dat_x.len() as u32; - // Z at k -> logical (k % n_log) - log_dat_z.push(k % n_log); - log_off_z[(k + 1) as usize] = log_dat_z.len() as u32; + // Z at k -> DEM output (k % n_dem_outputs) + dem_output_dat_z.push(k % n_dem_outputs); + dem_output_offsets_z[(k + 1) as usize] = dem_output_dat_z.len() as u32; // Y at k -> both det_dat_y.push(k % n_det); det_off_y[(k + 1) as usize] = det_dat_y.len() as u32; - log_dat_y.push(k % n_log); - log_off_y[(k + 1) as usize] = log_dat_y.len() as u32; + dem_output_dat_y.push(k % n_dem_outputs); + dem_output_offsets_y[(k + 1) as usize] = dem_output_dat_y.len() as u32; - // X touches no logicals (empty row) - log_off_x[(k + 1) as usize] = log_dat_x.len() as u32; + // X touches no DEM outputs (empty row) + dem_output_offsets_x[(k + 1) as usize] = dem_output_dat_x.len() as u32; // Z touches no detectors (empty row) det_off_z[(k + 1) as usize] = det_dat_z.len() as u32; } GpuInfluenceMapData::from_csr( - n_loc, n_det, n_log, det_off_x, det_dat_x, det_off_y, det_dat_y, det_off_z, det_dat_z, - log_off_x, log_dat_x, log_off_y, log_dat_y, log_off_z, log_dat_z, + n_loc, + n_det, + n_dem_outputs, + det_off_x, + det_dat_x, + det_off_y, + det_dat_y, + det_off_z, + det_dat_z, + dem_output_offsets_x, + dem_output_dat_x, + dem_output_offsets_y, + dem_output_dat_y, + dem_output_offsets_z, + dem_output_dat_z, ) } @@ -69,6 +82,40 @@ fn no_flips(flips: &[u32]) -> bool { flips.iter().all(|&w| w == 0) } +#[test] +fn logical_error_helpers_ignore_padding_bits() { + let result = GpuSamplingResult { + num_shots: 3, + detector_flips: vec![0; 3], + dem_output_flips: vec![ + 0b10, // shot 0: valid output 1 flips + 1 << 31, // shot 1: padding bit only, should be ignored + 0, // shot 2: no logical output + ], + num_detectors: 0, + num_dem_outputs: 2, + detector_words: 1, + dem_output_words: 1, + }; + + assert_eq!(result.count_logical_errors(), 1); + assert!(result.has_logical_error(0)); + assert!(!result.has_logical_error(1)); + assert!(!result.has_logical_error(2)); + + let tracked_only_result = GpuSamplingResult { + num_shots: 1, + detector_flips: vec![0], + dem_output_flips: vec![u32::MAX], + num_detectors: 0, + num_dem_outputs: 0, + detector_words: 1, + dem_output_words: 1, + }; + assert_eq!(tracked_only_result.count_logical_errors(), 0); + assert!(!tracked_only_result.has_logical_error(0)); +} + #[test] fn zero_prob_no_flips() { let map = simple_diagonal_map(32, 8, 4); @@ -109,12 +156,12 @@ fn empty_map_no_flips() { #[test] fn full_prob_saturates_parity() { // At p=1 every location fires every shot. For a map where every - // location touches at most one detector and one logical, every shot is + // location touches at most one detector and one DEM output, every shot is // an independent draw of X/Y/Z per location. The parity of the total // toggle count per detector is a deterministic function of the // per-location Pauli choices, but statistically the number of shots // that flip detector 0 should be non-zero. - let map = simple_diagonal_map(16, 1, 1); // all locations -> detector 0, logical 0 + let map = simple_diagonal_map(16, 1, 1); // all locations -> detector 0, DEM output 0 let Ok(mut sampler) = GpuInfluenceSampler::new(&map, 7) else { return; }; @@ -163,12 +210,15 @@ fn determinism_with_same_seed() { }; let ra = a.sample_uniform(64, 0.1); let rb = b.sample_uniform(64, 0.1); - assert_eq!(ra.count_logical_errors(), rb.count_logical_errors()); + assert_eq!( + ra.count_logical_errors(), + rb.count_logical_errors() + ); for shot in 0..64 { assert_eq!( ra.has_logical_error(shot), rb.has_logical_error(shot), - "shot {shot} logical mismatch" + "shot {shot} DEM-output mismatch" ); assert_eq!( ra.detector_flips_for_shot(shot), @@ -180,7 +230,7 @@ fn determinism_with_same_seed() { #[test] fn scaling_with_p_error() { - // Logical error rate should monotonically increase with p. + // logical error rate should monotonically increase with p. let map = simple_diagonal_map(32, 8, 4); let Ok(mut sampler) = GpuInfluenceSampler::new(&map, 42) else { return; diff --git a/crates/pecos-gpu-sims/tests/noisy_sampler_stats.rs b/crates/pecos-gpu-sims/tests/noisy_sampler_stats.rs index c68d2d88e..07da208ad 100644 --- a/crates/pecos-gpu-sims/tests/noisy_sampler_stats.rs +++ b/crates/pecos-gpu-sims/tests/noisy_sampler_stats.rs @@ -17,6 +17,7 @@ use pecos_gpu_sims::{CircuitBuilder, DepolarizingNoiseSampler, GpuNoisySampler}; /// For the trivial circuit `mz(0)` on |0> with measurement-error probability /// `p_meas`, the fraction of shots returning 1 should be close to `p_meas`. #[test] +#[ignore = "Slow statistical GPU audit; run explicitly with: cargo test -p pecos-gpu-sims --test noisy_sampler_stats --release -- --ignored --test-threads=1"] #[allow(clippy::cast_precision_loss)] // shots <= 4096, exact in f64 fn measurement_error_rate_matches_p() { let shots = 4096usize; @@ -70,6 +71,7 @@ fn zero_noise_zero_ones() { /// `noise_1q` after preparing |0> should flip the measurement with probability /// ~2p/3 (X and Y flip Z-basis; Z doesn't). Check within 4 sigma. #[test] +#[ignore = "Slow statistical GPU audit; run explicitly with: cargo test -p pecos-gpu-sims --test noisy_sampler_stats --release -- --ignored --test-threads=1"] #[allow(clippy::cast_precision_loss)] // shots bounded, exact in f64 fn depol1_flip_rate() { let shots = 4096usize; @@ -99,6 +101,7 @@ fn depol1_flip_rate() { /// by a quantity related to p2. This tests that p2 actually plumbs to the /// 2q noise path (not re-using p1). #[test] +#[ignore = "Slow statistical GPU audit; run explicitly with: cargo test -p pecos-gpu-sims --test noisy_sampler_stats --release -- --ignored --test-threads=1"] #[allow(clippy::cast_precision_loss)] // shots bounded, exact in f64 fn depol2_reduces_bell_correlation() { let shots = 4096usize; diff --git a/crates/pecos-hugr/src/engine.rs b/crates/pecos-hugr/src/engine.rs index f1091f6ed..49785da0d 100644 --- a/crates/pecos-hugr/src/engine.rs +++ b/crates/pecos-hugr/src/engine.rs @@ -2351,7 +2351,7 @@ mod tests { .expect("Failed to generate commands"); // Empty circuits should produce empty or minimal messages let is_empty = msg.is_empty().unwrap_or(true); - let has_no_ops = msg.quantum_ops().map(|ops| ops.is_empty()).unwrap_or(true); + let has_no_ops = msg.quantum_ops().map_or(true, |ops| ops.is_empty()); assert!(is_empty || has_no_ops); } diff --git a/crates/pecos-hugr/src/engine/handlers/arithmetic.rs b/crates/pecos-hugr/src/engine/handlers/arithmetic.rs index 1d63aa7bb..e9a202c09 100644 --- a/crates/pecos-hugr/src/engine/handlers/arithmetic.rs +++ b/crates/pecos-hugr/src/engine/handlers/arithmetic.rs @@ -163,7 +163,7 @@ impl HugrEngine { .get_input_value(hugr, node, 1) .and_then(|v| v.as_uint()); au.zip(bu) - .map(|(x, y)| if y != 0 { (x / y) as i64 } else { 0 }) + .map(|(x, y)| x.checked_div(y).map_or(0, |q| q as i64)) } "imod_s" | "imod" => a.zip(b).map(|(x, y)| if y != 0 { x % y } else { 0 }), #[allow(clippy::cast_possible_wrap)] diff --git a/crates/pecos-ldpc-decoders/pecos.toml b/crates/pecos-ldpc-decoders/pecos.toml index 9a2b4b7a7..55fab446c 100644 --- a/crates/pecos-ldpc-decoders/pecos.toml +++ b/crates/pecos-ldpc-decoders/pecos.toml @@ -10,13 +10,13 @@ sha256 = "6478edfe2f3305127cffe8caf73ea0176c53769f4bf1585be237eb30798c3b8e" description = "C++ Boost libraries" [dependencies.ldpc] -version = "31cf9f33872f32579af1efbe1e84552d42b03ea8" -url = "https://github.com/quantumgizmos/ldpc/archive/31cf9f33872f32579af1efbe1e84552d42b03ea8.tar.gz" -sha256 = "43ea9bfe543233c5f65e2dfb7966229df803040b4b26e25e99c3068eb23a797a" +version = "d3429964cd4ffe1abfc041c6ec8b8425cb174f40" +url = "https://github.com/quantumgizmos/ldpc/archive/d3429964cd4ffe1abfc041c6ec8b8425cb174f40.tar.gz" +sha256 = "76af0f01446ee7cbed33a47d6b597c10d8d12b2f10d508911b3d0763844d467e" description = "LDPC decoders" [dependencies.stim] -version = "bd60b73525fd5a9b30839020eb7554ad369e4337" -url = "https://github.com/quantumlib/Stim/archive/bd60b73525fd5a9b30839020eb7554ad369e4337.tar.gz" -sha256 = "2a4be24295ce3018d79e08369b31e401a2d33cd8b3a75675d57dac3afd9de37d" +version = "213275795e49027772bea7c610b6aac3a80583e1" +url = "https://github.com/quantumlib/Stim/archive/213275795e49027772bea7c610b6aac3a80583e1.tar.gz" +sha256 = "b63c4ae94494a8819d440757776cf80a829ec1e30454fa7c9b0f670e981938ab" description = "Stabilizer simulator for QEC" diff --git a/crates/pecos-ldpc-decoders/src/bridge.cpp b/crates/pecos-ldpc-decoders/src/bridge.cpp index 362249f23..473b7bd7b 100644 --- a/crates/pecos-ldpc-decoders/src/bridge.cpp +++ b/crates/pecos-ldpc-decoders/src/bridge.cpp @@ -102,7 +102,7 @@ std::unique_ptr create_bp_osd_decoder( omp_thread_count, serial_schedule_vec, random_schedule_seed, - true, // random_schedule_at_every_iteration + serial_schedule_vec.empty(), // random_serial_schedule: use random if no fixed schedule static_cast(input_vector_type) ); @@ -254,7 +254,7 @@ std::unique_ptr create_bp_lsd_decoder( omp_thread_count, serial_schedule_vec, random_schedule_seed, - true, // random_schedule_at_every_iteration + serial_schedule_vec.empty(), // random_serial_schedule: use random if no fixed schedule static_cast(input_vector_type) ); diff --git a/crates/pecos-ldpc-decoders/src/core_traits_simple.rs b/crates/pecos-ldpc-decoders/src/core_traits_simple.rs index c786919c2..7201162c1 100644 --- a/crates/pecos-ldpc-decoders/src/core_traits_simple.rs +++ b/crates/pecos-ldpc-decoders/src/core_traits_simple.rs @@ -5,7 +5,7 @@ //! parameters required by LDPC decoders. use crate::decoders::{ - BeliefFindDecoder, BpLsdDecoder, BpOsdDecoder, FlipDecoder, SoftInfoBpDecoder, + BeliefFindDecoder, BpLsdDecoder, BpOsdDecoder, FlipDecoder, SoftInfoBpDecoder, UnionFindDecoder, }; use crate::{DecodingResult, LdpcError}; use ndarray::ArrayView1; @@ -37,6 +37,10 @@ impl DecodingResultTrait for DecodingResult { self.converged } + fn correction(&self) -> &[u8] { + self.decoding.as_slice().unwrap_or(&[]) + } + fn iterations(&self) -> Option { Some(self.iterations) } @@ -88,6 +92,24 @@ impl Decoder for BpLsdDecoder { } } +/// Implement Decoder trait for `UnionFindDecoder` +impl Decoder for UnionFindDecoder { + type Result = DecodingResult; + type Error = LdpcError; + + fn decode(&mut self, input: &ArrayView1) -> Result { + self.decode(input, &[], 0) + } + + fn check_count(&self) -> usize { + self.check_count() + } + + fn bit_count(&self) -> usize { + self.bit_count() + } +} + /// Implement Decoder trait for `FlipDecoder` impl Decoder for FlipDecoder { type Result = DecodingResult; diff --git a/crates/pecos-mwpf/Cargo.toml b/crates/pecos-mwpf/Cargo.toml new file mode 100644 index 000000000..64e6302e7 --- /dev/null +++ b/crates/pecos-mwpf/Cargo.toml @@ -0,0 +1,25 @@ +[package] +name = "pecos-mwpf" +version.workspace = true +edition.workspace = true +readme = "README.md" +authors.workspace = true +homepage.workspace = true +repository.workspace = true +license.workspace = true +keywords.workspace = true +categories.workspace = true +description = "MWPF hypergraph decoder for PECOS" + +[dependencies] +pecos-decoder-core.workspace = true +ndarray.workspace = true +thiserror.workspace = true +mwpf.workspace = true +serde_json.workspace = true + +[lib] +name = "pecos_mwpf" + +[lints] +workspace = true diff --git a/crates/pecos-mwpf/README.md b/crates/pecos-mwpf/README.md new file mode 100644 index 000000000..9772ce17f --- /dev/null +++ b/crates/pecos-mwpf/README.md @@ -0,0 +1,16 @@ +# pecos-mwpf + +PECOS wrapper for the [MWPF (Minimum-Weight Parity Factor)](https://github.com/yuewuo/mwpf) hypergraph decoder by Yue Wu (Yale). + +Unlike MWPM decoders (PyMatching, Fusion Blossom), MWPF handles hyperedges natively. This means it can decode Y errors, depolarizing noise, color codes, and small QLDPC codes with higher accuracy than graph-based decoders that must decompose hyperedges. + +The tradeoff is a heavier worst-case latency tail. MWPF is best suited for offline benchmarks, correlated-noise studies, and accuracy-first decoding. + +## Key configuration + +- `cluster_node_limit` (default 50): Controls accuracy vs speed. Lower values are faster. +- `timeout`: Optional solver timeout in seconds. + +## License + +MWPF is MIT-licensed. This wrapper is Apache-2.0-licensed as part of PECOS. diff --git a/crates/pecos-mwpf/src/core_traits.rs b/crates/pecos-mwpf/src/core_traits.rs new file mode 100644 index 000000000..fe7922ccb --- /dev/null +++ b/crates/pecos-mwpf/src/core_traits.rs @@ -0,0 +1,31 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Implementation of core decoder traits for MWPF + +use crate::decoder::MwpfDecoder; + +/// Implement `ObservableDecoder` for `MwpfDecoder`. +/// +/// This is the primary trait used by the fast decode path +/// (`SampleBatch.decode_count`, `sample_decode_count`, etc.). +impl pecos_decoder_core::ObservableDecoder for MwpfDecoder { + fn decode_to_observables( + &mut self, + syndrome: &[u8], + ) -> std::result::Result { + let result = self + .decode_syndrome(syndrome) + .map_err(|e| pecos_decoder_core::DecoderError::DecodingFailed(e.to_string()))?; + Ok(result.observable_mask) + } +} diff --git a/crates/pecos-mwpf/src/decoder.rs b/crates/pecos-mwpf/src/decoder.rs new file mode 100644 index 000000000..f9a278839 --- /dev/null +++ b/crates/pecos-mwpf/src/decoder.rs @@ -0,0 +1,335 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! MWPF hypergraph decoder implementation +//! +//! Wraps the Minimum-Weight Parity Factor solver by Yue Wu (Yale). +//! Unlike MWPM decoders, MWPF handles hyperedges natively -- it does not +//! need graphlike decomposition, so it can decode Y errors, depolarizing +//! noise, color codes, and small QLDPC codes with higher accuracy. + +use crate::errors::{MwpfError, Result}; +use mwpf::mwpf_solver::{ + SolverBPWrapper, SolverBase, SolverSerialJointSingleHair, SolverSerialSingleHair, + SolverSerialUnionFind, SolverTrait, +}; +use mwpf::util::{HyperEdge, SolverInitializer, SyndromePattern}; +use pecos_decoder_core::dem::DemCheckMatrix; +use std::sync::Arc; + +/// Which MWPF solver variant to use. +#[derive(Debug, Clone, Copy, Default)] +pub enum MwpfSolverType { + /// Union-find only -- fastest, lowest accuracy. + UnionFind, + /// Single hair plugin pass -- moderate speed and accuracy. + SingleHair, + /// BP preprocessing + `JointSingleHair`. BP guides the solver to + /// converge faster while maintaining accuracy. + BpHybrid, + /// Joint single hair with repeated optimization -- best accuracy, slowest. + #[default] + JointSingleHair, +} + +/// Configuration for the MWPF decoder. +/// +/// MWPF has three knobs at the solver level: +/// - `cluster_node_limit`: controls optimization depth (accuracy vs speed) +/// - `timeout`: wall-clock cap, falls back to union-find on expiry +/// - `only_solve_primal_once`: skip intermediate primal solutions +#[derive(Debug, Clone, Copy)] +pub struct MwpfConfig { + /// Which solver variant to use. Default: `JointSingleHair` (best accuracy). + pub solver_type: MwpfSolverType, + + /// Maximum number of nodes per cluster during optimization. + /// Lower values are faster but less accurate. + /// Default: 50 (paper's sweet spot for d=7 circuit-level). + pub cluster_node_limit: usize, + + /// Timeout in seconds for the solver. When exceeded, the solver stops + /// optimizing and returns the best solution found so far (union-find + /// baseline). `None` means no timeout. + /// + /// Setting this is the main way to tame the p99 latency tail. + pub timeout: Option, + + /// If true, solve the primal only once at the end instead of after each + /// plugin iteration. Can be faster at the cost of missing local optima. + pub only_solve_primal_once: bool, +} + +impl Default for MwpfConfig { + fn default() -> Self { + Self { + solver_type: MwpfSolverType::default(), + cluster_node_limit: 50, + timeout: None, + only_solve_primal_once: false, + } + } +} + +impl MwpfConfig { + /// Build the `serde_json` config object for the MWPF solver. + fn to_solver_config(self) -> serde_json::Value { + let mut map = serde_json::Map::new(); + map.insert( + "cluster_node_limit".to_string(), + serde_json::Number::from(self.cluster_node_limit).into(), + ); + if let Some(t) = self.timeout + && let Some(n) = serde_json::Number::from_f64(t) + { + map.insert("timeout".to_string(), serde_json::Value::Number(n)); + } + if self.only_solve_primal_once { + map.insert("only_solve_primal_once".to_string(), true.into()); + } + serde_json::Value::Object(map) + } +} + +/// Decoding result from the MWPF decoder. +#[derive(Debug, Clone)] +pub struct MwpfDecodingResult { + /// Observable prediction as a bitmask (bit i set = observable i flipped). + pub observable_mask: u64, + /// Edge indices in the solution subgraph. + pub subgraph: Vec, +} + +/// Internal solver enum holding any MWPF solver variant. +enum Solver { + UnionFind(SolverSerialUnionFind), + SingleHair(SolverSerialSingleHair), + JointSingleHair(SolverSerialJointSingleHair), + BpHybrid(SolverBPWrapper), +} + +impl Solver { + fn solve(&mut self, syndrome: SyndromePattern) { + match self { + Self::UnionFind(s) => s.solve(syndrome), + Self::SingleHair(s) => s.solve(syndrome), + Self::JointSingleHair(s) => s.solve(syndrome), + Self::BpHybrid(s) => s.solve(syndrome), + } + } + + fn subgraph(&mut self) -> mwpf::util::OutputSubgraph { + match self { + Self::UnionFind(s) => s.subgraph(), + Self::SingleHair(s) => s.subgraph(), + Self::JointSingleHair(s) => s.subgraph(), + Self::BpHybrid(s) => s.subgraph(), + } + } + + fn clear(&mut self) { + match self { + Self::UnionFind(s) => s.clear(), + Self::SingleHair(s) => s.clear(), + Self::JointSingleHair(s) => s.clear(), + Self::BpHybrid(s) => s.clear(), + } + } +} + +/// MWPF hypergraph decoder. +/// +/// Constructed from a full (non-decomposed) DEM string. Each error mechanism +/// in the DEM becomes one hyperedge in the solver, preserving correlations +/// that MWPM decoders must decompose away. +pub struct MwpfDecoder { + /// The MWPF solver instance. + solver: Solver, + /// Per-edge observable bitmask (indexed by deduped edge index). + edge_obs: Vec, + /// Number of detectors. + num_detectors: usize, + /// Reusable buffer for defect vertices (avoids per-shot allocation). + defect_buf: Vec, +} + +impl MwpfDecoder { + /// Create a decoder from a DEM string and configuration. + /// + /// The DEM should be full (non-decomposed) to preserve hyperedges. + /// + /// # Errors + /// + /// Returns `MwpfError` if the DEM is malformed or the solver cannot be + /// constructed. + pub fn from_dem(dem_str: &str, config: MwpfConfig) -> Result { + let dem = DemCheckMatrix::from_dem_str(dem_str) + .map_err(|e| MwpfError::InvalidDem(e.to_string()))?; + + // Build hyperedges from the check matrix. Each mechanism (column) becomes + // one HyperEdge with all its incident detectors. + // Merge duplicate vertex sets and build per-edge observable masks. + // Decomposed DEMs can have multiple mechanisms with the same detector set. + // Merge by combining probabilities (independent union) and tracking the + // observable from the highest-probability mechanism (first-observable-wins). + use std::collections::BTreeMap; + struct EdgeInfo { + prob: f64, + obs_mask: u64, + best_prob: f64, + } + let mut edge_map: BTreeMap, EdgeInfo> = BTreeMap::new(); + for m in 0..dem.num_mechanisms { + let p = dem.error_priors[m]; + if p <= 0.0 { + continue; + } + + let vertices: Vec = (0..dem.num_detectors) + .filter(|&d| dem.check_matrix[[d, m]] != 0) + .collect(); + + if vertices.is_empty() { + continue; + } + + // Compute this mechanism's observable mask. + let mut obs: u64 = 0; + for o in 0..dem.num_observables { + if dem.observable_matrix[[o, m]] != 0 { + obs |= 1 << o; + } + } + + let entry = edge_map.entry(vertices).or_insert(EdgeInfo { + prob: 0.0, + obs_mask: obs, + best_prob: p, + }); + let old_p = entry.prob; + entry.prob = old_p + p - old_p * p; + if p > entry.best_prob { + entry.obs_mask = obs; + entry.best_prob = p; + } + } + + let mut hyperedges = Vec::with_capacity(edge_map.len()); + let mut edge_obs = Vec::with_capacity(edge_map.len()); + for (vertices, info) in edge_map { + let weight = if info.prob < 1.0 { + ((1.0 - info.prob) / info.prob).ln() + } else { + 0.0 + }; + hyperedges.push(HyperEdge::new(vertices, weight.into())); + edge_obs.push(info.obs_mask); + } + + let initializer = Arc::new(SolverInitializer::new(dem.num_detectors, hyperedges)); + let solver_config = config.to_solver_config(); + let solver = match config.solver_type { + MwpfSolverType::UnionFind => { + Solver::UnionFind(SolverSerialUnionFind::new(&initializer, solver_config)) + } + MwpfSolverType::SingleHair => { + Solver::SingleHair(SolverSerialSingleHair::new(&initializer, solver_config)) + } + MwpfSolverType::JointSingleHair => Solver::JointSingleHair( + SolverSerialJointSingleHair::new(&initializer, solver_config), + ), + MwpfSolverType::BpHybrid => { + let base = SolverBase { + inner: mwpf::mwpf_solver::SolverEnum::SolverSerialJointSingleHair( + SolverSerialJointSingleHair::new(&initializer, solver_config), + ), + }; + // BP with 50 iterations and 0.5 application ratio (paper defaults). + Solver::BpHybrid(SolverBPWrapper::new(base, 50, 0.5)) + } + }; + + Ok(Self { + solver, + edge_obs, + num_detectors: dem.num_detectors, + defect_buf: Vec::new(), + }) + } + + /// Decode a syndrome and return the observable mask. + /// + /// The syndrome is a byte slice of length `num_detectors`, where + /// non-zero entries indicate triggered detectors. + /// + /// # Errors + /// + /// Returns `MwpfError::DecodingFailed` if decoding fails. + pub fn decode_syndrome(&mut self, syndrome: &[u8]) -> Result { + // Reuse defect buffer across shots + self.defect_buf.clear(); + for (i, &v) in syndrome.iter().enumerate() { + if v != 0 { + self.defect_buf.push(i); + } + } + + if self.defect_buf.is_empty() { + return Ok(MwpfDecodingResult { + observable_mask: 0, + subgraph: Vec::new(), + }); + } + + self.solver + .solve(SyndromePattern::new_vertices(self.defect_buf.clone())); + let output = self.solver.subgraph(); + self.solver.clear(); + + // Compute observable mask from the correction subgraph. + let mut observable_mask = 0u64; + for &edge_idx in &output.subgraph { + if edge_idx < self.edge_obs.len() { + observable_mask ^= self.edge_obs[edge_idx]; + } + } + + Ok(MwpfDecodingResult { + observable_mask, + subgraph: output.subgraph, + }) + } + + /// Number of detectors in the model. + #[must_use] + pub fn num_detectors(&self) -> usize { + self.num_detectors + } + + /// Number of edges in the model (after deduplication). + #[must_use] + pub fn num_edges(&self) -> usize { + self.edge_obs.len() + } + + /// Number of observables in the model. + #[must_use] + pub fn num_observables(&self) -> usize { + let mut max_bit = 0usize; + for &obs in &self.edge_obs { + if obs != 0 { + max_bit = max_bit.max(64 - obs.leading_zeros() as usize); + } + } + max_bit + } +} diff --git a/crates/pecos-mwpf/src/errors.rs b/crates/pecos-mwpf/src/errors.rs new file mode 100644 index 000000000..dd95cfd6b --- /dev/null +++ b/crates/pecos-mwpf/src/errors.rs @@ -0,0 +1,46 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Error types for the MWPF decoder + +use thiserror::Error; + +/// Error type for MWPF operations +#[derive(Error, Debug)] +pub enum MwpfError { + /// Configuration error + #[error("Configuration error: {0}")] + Configuration(String), + + /// Decoding failed + #[error("Decoding failed: {0}")] + DecodingFailed(String), + + /// Invalid DEM format + #[error("Invalid DEM: {0}")] + InvalidDem(String), +} + +/// Result type for MWPF operations +pub type Result = std::result::Result; + +/// Convert `MwpfError` to `DecoderError` +impl From for pecos_decoder_core::DecoderError { + fn from(e: MwpfError) -> Self { + match e { + MwpfError::Configuration(msg) | MwpfError::InvalidDem(msg) => { + pecos_decoder_core::DecoderError::InvalidConfiguration(msg) + } + MwpfError::DecodingFailed(msg) => pecos_decoder_core::DecoderError::DecodingFailed(msg), + } + } +} diff --git a/crates/pecos-mwpf/src/lib.rs b/crates/pecos-mwpf/src/lib.rs new file mode 100644 index 000000000..81f301876 --- /dev/null +++ b/crates/pecos-mwpf/src/lib.rs @@ -0,0 +1,36 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! MWPF hypergraph decoder module +//! +//! This module provides Rust bindings for the Minimum-Weight Parity Factor +//! decoder for quantum error correction. Unlike MWPM decoders, MWPF handles +//! hyperedges natively -- it can decode Y errors, depolarizing noise, color +//! codes, and small QLDPC codes with higher accuracy than graphlike decoders. +//! +//! Tradeoff: MWPF has a heavier worst-case latency tail than MWPM. Good for +//! offline benchmarks, correlated-noise studies, and accuracy-first decoding. + +// Allow casts between float/int for weight conversions +#![allow( + clippy::cast_possible_truncation, + clippy::cast_precision_loss, + clippy::cast_sign_loss +)] + +pub mod core_traits; +pub mod decoder; +pub mod errors; + +// Re-export main types +pub use decoder::{MwpfConfig, MwpfDecoder, MwpfDecodingResult, MwpfSolverType}; +pub use errors::MwpfError; diff --git a/crates/pecos-mwpf/tests/basic.rs b/crates/pecos-mwpf/tests/basic.rs new file mode 100644 index 000000000..6f3172cb8 --- /dev/null +++ b/crates/pecos-mwpf/tests/basic.rs @@ -0,0 +1,112 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +use pecos_decoder_core::ObservableDecoder; +use pecos_mwpf::{MwpfConfig, MwpfDecoder}; + +/// Simple repetition-code-like DEM: two detectors, two error mechanisms. +const SIMPLE_DEM: &str = "\ +error(0.1) D0 D1 L0 +error(0.1) D1 +"; + +/// A d=3 surface-code-like DEM with a hyperedge (3 detectors). +const HYPEREDGE_DEM: &str = "\ +error(0.01) D0 D1 L0 +error(0.01) D1 D2 +error(0.01) D0 D1 D2 L0 +error(0.01) D2 +"; + +#[test] +fn construct_from_simple_dem() { + let decoder = MwpfDecoder::from_dem(SIMPLE_DEM, MwpfConfig::default()); + assert!(decoder.is_ok()); + let decoder = decoder.unwrap(); + assert_eq!(decoder.num_detectors(), 2); + assert_eq!(decoder.num_observables(), 1); +} + +#[test] +fn construct_from_hyperedge_dem() { + let decoder = MwpfDecoder::from_dem(HYPEREDGE_DEM, MwpfConfig::default()); + assert!(decoder.is_ok()); + let decoder = decoder.unwrap(); + assert_eq!(decoder.num_detectors(), 3); + assert_eq!(decoder.num_observables(), 1); +} + +#[test] +fn decode_no_errors() { + let mut decoder = MwpfDecoder::from_dem(SIMPLE_DEM, MwpfConfig::default()).unwrap(); + // No detectors triggered -> no observable flips. + let syndrome = vec![0u8; 2]; + let result = decoder.decode_syndrome(&syndrome).unwrap(); + assert_eq!(result.observable_mask, 0); +} + +#[test] +fn decode_single_error() { + let mut decoder = MwpfDecoder::from_dem(SIMPLE_DEM, MwpfConfig::default()).unwrap(); + // Both D0 and D1 triggered -> mechanism 0 (D0 D1 L0), observable L0 flips. + let syndrome = vec![1u8, 1]; + let result = decoder.decode_syndrome(&syndrome).unwrap(); + assert_eq!(result.observable_mask, 1); +} + +#[test] +fn decode_boundary_error() { + let mut decoder = MwpfDecoder::from_dem(SIMPLE_DEM, MwpfConfig::default()).unwrap(); + // Only D1 triggered -> mechanism 1 (D1, boundary), no observable flip. + let syndrome = vec![0u8, 1]; + let result = decoder.decode_syndrome(&syndrome).unwrap(); + assert_eq!(result.observable_mask, 0); +} + +#[test] +fn observable_decoder_trait() { + let mut decoder = MwpfDecoder::from_dem(SIMPLE_DEM, MwpfConfig::default()).unwrap(); + let mask = decoder.decode_to_observables(&[1, 1]).unwrap(); + assert_eq!(mask, 1); +} + +#[test] +fn decode_multiple_shots() { + // Verify solver reuse works (clear() between shots). + let mut decoder = MwpfDecoder::from_dem(SIMPLE_DEM, MwpfConfig::default()).unwrap(); + for _ in 0..10 { + let _ = decoder.decode_syndrome(&[1, 1]).unwrap(); + let _ = decoder.decode_syndrome(&[0, 1]).unwrap(); + let _ = decoder.decode_syndrome(&[0, 0]).unwrap(); + } +} + +#[test] +fn custom_config() { + let config = MwpfConfig { + cluster_node_limit: 10, + timeout: Some(5.0), + ..MwpfConfig::default() + }; + let mut decoder = MwpfDecoder::from_dem(SIMPLE_DEM, config).unwrap(); + let result = decoder.decode_syndrome(&[1, 1]).unwrap(); + assert_eq!(result.observable_mask, 1); +} + +#[test] +fn hyperedge_decode() { + let mut decoder = MwpfDecoder::from_dem(HYPEREDGE_DEM, MwpfConfig::default()).unwrap(); + // All three detectors triggered: the hyperedge mechanism (D0 D1 D2 L0) + // is the minimum weight explanation. + let result = decoder.decode_syndrome(&[1, 1, 1]).unwrap(); + assert_eq!(result.observable_mask, 1); +} diff --git a/crates/pecos-num/src/array.rs b/crates/pecos-num/src/array.rs index 31f7430e6..acd6615e1 100644 --- a/crates/pecos-num/src/array.rs +++ b/crates/pecos-num/src/array.rs @@ -358,6 +358,46 @@ pub fn linspace(start: f64, stop: f64, num: usize, endpoint: bool) -> Array1 Array1 { + assert!( + start > 0.0, + "geomspace: start must be positive, got {start}" + ); + assert!(stop > 0.0, "geomspace: stop must be positive, got {stop}"); + + let log_start = start.ln(); + let log_stop = stop.ln(); + let log_values = linspace(log_start, log_stop, num, endpoint); + log_values.mapv(f64::exp) +} + // Note: sum() for slices removed - use values.iter().sum() directly (idiomatic Rust) // sum_axis() below is kept for multi-dimensional operations diff --git a/crates/pecos-num/src/lib.rs b/crates/pecos-num/src/lib.rs index 180c78c92..e95d1dbd3 100644 --- a/crates/pecos-num/src/lib.rs +++ b/crates/pecos-num/src/lib.rs @@ -46,6 +46,7 @@ pub mod polynomial; pub mod prelude; pub mod random; pub mod stats; +pub mod z2_linalg; pub use compare::{allclose, relative_eq}; pub use curve_fit::{CurveFitError, CurveFitOptions, CurveFitResult, curve_fit}; diff --git a/crates/pecos-num/src/prelude.rs b/crates/pecos-num/src/prelude.rs index 5ea6129d5..b8e0044bb 100644 --- a/crates/pecos-num/src/prelude.rs +++ b/crates/pecos-num/src/prelude.rs @@ -99,8 +99,8 @@ pub use num_complex::{Complex, Complex32, Complex64}; // Re-export array operations // Note: sum() for slices removed - use .iter().sum() directly (idiomatic Rust) pub use crate::array::{ - arange, broadcast_shapes, broadcast_to, delete, diag, diag_matrix, linspace, ones, sum_axis, - zeros, + arange, broadcast_shapes, broadcast_to, delete, diag, diag_matrix, geomspace, linspace, ones, + sum_axis, zeros, }; // Re-export graph types and algorithms diff --git a/crates/pecos-num/src/z2_linalg.rs b/crates/pecos-num/src/z2_linalg.rs new file mode 100644 index 000000000..7c91088f4 --- /dev/null +++ b/crates/pecos-num/src/z2_linalg.rs @@ -0,0 +1,264 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Sparse linear algebra over `Z_2` (GF(2)). +//! +//! Operations on binary vectors and matrices represented as sorted index +//! sets. This is the natural representation for QEC detector definitions +//! where each detector is an XOR (sum mod 2) of a small number of +//! measurements. +//! +//! # Representation +//! +//! A `Z_2` vector is a sorted `Vec` of indices where the vector has +//! value 1. Addition (XOR) is computed as sorted-merge symmetric difference. +//! A `Z_2` matrix is a `Vec>` of row vectors. +//! +//! # Example +//! +//! ``` +//! use pecos_num::z2_linalg::{z2_rank, z2_xor}; +//! +//! // Three detectors: D0=[0], D1=[1], D2=[0,1] +//! // D2 = D0 + D1 → rank should be 2 +//! let rows = vec![vec![0], vec![1], vec![0, 1]]; +//! assert_eq!(z2_rank(&rows), 2); +//! +//! // XOR of two sparse vectors +//! assert_eq!(z2_xor(&[1, 3, 5], &[2, 3, 4]), vec![1, 2, 4, 5]); +//! ``` + +use std::collections::BTreeMap; + +/// Compute the rank of a binary matrix over `Z_2`. +/// +/// Each row is a sorted list of column indices where the row has value 1. +/// Uses sparse Gaussian elimination with leftmost-column pivoting. +/// +/// Complexity: O(n * k * log(n)) where n is the number of rows and k is +/// the average number of nonzeros per row. For QEC detectors with k ≈ 2, +/// this is effectively O(n * log(n)). +/// +/// # Arguments +/// +/// * `rows` - Binary matrix as a slice of sorted index vectors. +/// +/// # Example +/// +/// ``` +/// use pecos_num::z2_linalg::z2_rank; +/// +/// // Two independent rows +/// assert_eq!(z2_rank(&[vec![0], vec![1]]), 2); +/// +/// // Three rows, one dependent (D2 = D0 + D1) +/// assert_eq!(z2_rank(&[vec![0, 1], vec![1, 2], vec![0, 2]]), 2); +/// ``` +#[must_use] +pub fn z2_rank(rows: &[Vec]) -> usize { + let mut work: Vec> = rows.to_vec(); + let mut pivot_rows: BTreeMap = BTreeMap::new(); + let mut rank = 0; + + for i in 0..work.len() { + // Reduce row i by XOR-ing with existing pivot rows + loop { + if work[i].is_empty() { + break; + } + let min_col = work[i][0]; + if let Some(&pr) = pivot_rows.get(&min_col) { + let pivot = work[pr].clone(); + work[i] = z2_xor(&work[i], &pivot); + } else { + break; + } + } + + if !work[i].is_empty() { + let min_col = work[i][0]; + pivot_rows.insert(min_col, i); + rank += 1; + } + } + + rank +} + +/// Compute the rank of detector definitions given as record offsets. +/// +/// Each record is a list of measurement indices (possibly negative for +/// Stim-style offsets from the end). Negative offsets are resolved against +/// `num_measurements`. +/// +/// # Arguments +/// +/// * `records` - Detector definitions as record offset lists. +/// * `num_measurements` - Total number of measurements (for resolving +/// negative offsets). +#[must_use] +pub fn z2_rank_from_records(records: &[Vec], num_measurements: usize) -> usize { + let rows: Vec> = records + .iter() + .map(|record| { + let mut indices: Vec = record + .iter() + .filter_map(|&offset| { + let abs = if offset < 0 { + num_measurements.checked_sub(offset.unsigned_abs() as usize)? + } else { + offset.unsigned_abs() as usize + }; + (abs < num_measurements).then_some(abs) + }) + .collect(); + indices.sort_unstable(); + indices.dedup(); + indices + }) + .collect(); + + z2_rank(&rows) +} + +/// XOR (symmetric difference) of two sorted `Z_2` vectors. +/// +/// Both inputs must be sorted and deduplicated. The result is also sorted +/// and deduplicated. +/// +/// # Example +/// +/// ``` +/// use pecos_num::z2_linalg::z2_xor; +/// +/// assert_eq!(z2_xor(&[1, 3, 5], &[2, 3, 4]), vec![1, 2, 4, 5]); +/// assert_eq!(z2_xor(&[0, 1], &[0, 1]), Vec::::new()); +/// assert_eq!(z2_xor(&[], &[1, 2, 3]), vec![1, 2, 3]); +/// ``` +#[must_use] +pub fn z2_xor(a: &[usize], b: &[usize]) -> Vec { + let mut result = Vec::with_capacity(a.len() + b.len()); + let (mut i, mut j) = (0, 0); + + while i < a.len() && j < b.len() { + match a[i].cmp(&b[j]) { + std::cmp::Ordering::Less => { + result.push(a[i]); + i += 1; + } + std::cmp::Ordering::Greater => { + result.push(b[j]); + j += 1; + } + std::cmp::Ordering::Equal => { + i += 1; + j += 1; + } + } + } + + result.extend_from_slice(&a[i..]); + result.extend_from_slice(&b[j..]); + result +} + +/// Check if a set of `Z_2` row vectors are linearly independent. +/// +/// # Example +/// +/// ``` +/// use pecos_num::z2_linalg::z2_are_independent; +/// +/// assert!(z2_are_independent(&[vec![0], vec![1]])); +/// assert!(!z2_are_independent(&[vec![0], vec![1], vec![0, 1]])); +/// ``` +#[must_use] +pub fn z2_are_independent(rows: &[Vec]) -> bool { + z2_rank(rows) == rows.len() +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn rank_empty() { + assert_eq!(z2_rank(&[]), 0); + } + + #[test] + fn rank_single() { + assert_eq!(z2_rank(&[vec![0]]), 1); + } + + #[test] + fn rank_independent() { + assert_eq!(z2_rank(&[vec![0], vec![1], vec![2]]), 3); + } + + #[test] + fn rank_dependent() { + assert_eq!(z2_rank(&[vec![0], vec![1], vec![0, 1]]), 2); + } + + #[test] + fn rank_all_identical() { + assert_eq!(z2_rank(&[vec![0, 1], vec![0, 1], vec![0, 1]]), 1); + } + + #[test] + fn rank_chain_dependent() { + // D0=[0,1], D1=[1,2], D2=[0,2] → D2 = D0 + D1 → rank 2 + assert_eq!(z2_rank(&[vec![0, 1], vec![1, 2], vec![0, 2]]), 2); + } + + #[test] + fn rank_large_sparse() { + let rows: Vec> = (0..1000).map(|i| vec![i]).collect(); + assert_eq!(z2_rank(&rows), 1000); + } + + #[test] + fn rank_from_records_negative_offsets() { + let records = vec![vec![-1i32], vec![-2]]; + assert_eq!(z2_rank_from_records(&records, 10), 2); + } + + #[test] + fn rank_from_records_dependent() { + let records = vec![vec![0i32], vec![1], vec![0, 1]]; + assert_eq!(z2_rank_from_records(&records, 10), 2); + } + + #[test] + fn xor_basic() { + assert_eq!(z2_xor(&[1, 3, 5], &[2, 3, 4]), vec![1, 2, 4, 5]); + } + + #[test] + fn xor_cancel() { + assert_eq!(z2_xor(&[1, 2], &[1, 2]), Vec::::new()); + } + + #[test] + fn xor_empty() { + assert_eq!(z2_xor(&[], &[1, 2]), vec![1, 2]); + assert_eq!(z2_xor(&[1, 2], &[]), vec![1, 2]); + } + + #[test] + fn independence_check() { + assert!(z2_are_independent(&[vec![0], vec![1]])); + assert!(!z2_are_independent(&[vec![0], vec![1], vec![0, 1]])); + assert!(z2_are_independent(&[])); + } +} diff --git a/crates/pecos-phir-json/src/v0_1/ast.rs b/crates/pecos-phir-json/src/v0_1/ast.rs index 4f565dfc9..f61b51a1c 100644 --- a/crates/pecos-phir-json/src/v0_1/ast.rs +++ b/crates/pecos-phir-json/src/v0_1/ast.rs @@ -1,4 +1,4 @@ -use serde::{Deserialize, Deserializer}; +use serde::Deserialize; use std::collections::BTreeMap; use std::f64::consts::PI; @@ -12,9 +12,13 @@ pub struct PHIRProgram { pub ops: Vec, } -/// Represents an operation in the PHIR program -#[derive(Debug, Deserialize, Clone)] -#[serde(untagged)] +/// Represents an operation in the PHIR program. +/// +/// Deserialized via a manual `Deserialize` impl that inspects which discriminating +/// key is present (`qop`, `cop`, `block`, `mop`, `meta`, `data`, `//`). +/// This avoids `#[serde(untagged)]` whose `ContentDeserializer` can silently fail +/// with certain nested types (serde issue 1183). +#[derive(Debug, Clone)] pub enum Operation { /// Variable definition for quantum or classical variables VariableDefinition { @@ -22,63 +26,45 @@ pub enum Operation { data_type: String, variable: String, /// Size in bits. Optional -- if omitted, inferred from `data_type`. - #[serde(default)] size: Option, }, /// Quantum operation (gates, measurements) QuantumOp { qop: String, - #[serde(default)] - #[serde(deserialize_with = "deserialize_angles_to_radians")] - angles: Option>, // Now just Vec in radians, no unit string + /// Angles in radians (converted from the JSON `[[values...], "unit"]` format) + angles: Option>, args: Vec, - #[serde(default)] returns: Vec<(String, usize)>, - #[serde(default)] metadata: Option>, }, /// Classical operation (e.g., Result for exporting values) ClassicalOp { cop: String, - #[serde(default)] args: Vec, - #[serde(default)] returns: Vec, - #[serde(default)] metadata: Option>, - #[serde(default, skip_serializing_if = "Option::is_none")] - function: Option, // For ffcall + function: Option, }, /// Block operation (e.g., sequence, qparallel, if) Block { block: String, - #[serde(default)] ops: Vec, - #[serde(default)] condition: Option, - #[serde(default)] true_branch: Option>, - #[serde(default)] false_branch: Option>, - #[serde(default)] metadata: Option>, }, /// Machine operation (e.g., Idle, Transport) MachineOp { mop: String, - #[serde(default)] args: Option>, - #[serde(default)] duration: Option<(f64, String)>, - #[serde(default)] metadata: Option>, }, /// Meta instruction (e.g., barrier) MetaInstruction { meta: String, - #[serde(default)] args: Vec<(String, usize)>, - #[serde(default)] metadata: Option>, }, /// Data export (`cvar_export`) -- specifies which variables to export @@ -87,10 +73,247 @@ pub enum Operation { variables: Vec, }, /// Comment - Comment { - #[serde(rename = "//")] - comment: String, - }, + Comment { comment: String }, +} + +// --------------------------------------------------------------------------- +// Manual Deserialize for Operation -- key-based dispatch on serde_json::Value +// --------------------------------------------------------------------------- + +/// Convert raw JSON angles `[[values...], "unit"]` to radians. +fn convert_angles(raw: &serde_json::Value) -> Result>, String> { + if raw.is_null() { + return Ok(None); + } + let arr = raw.as_array().ok_or("angles: expected array")?; + if arr.len() != 2 { + return Err(format!( + "angles: expected [values, unit], got {} elements", + arr.len() + )); + } + let values = arr[0] + .as_array() + .ok_or("angles: first element must be an array of numbers")? + .iter() + .map(|v| { + v.as_f64() + .ok_or_else(|| format!("angles: expected number, got {v}")) + }) + .collect::, _>>()?; + let unit = arr[1] + .as_str() + .ok_or("angles: second element must be a string")?; + match unit { + "rad" => Ok(Some(values)), + "deg" => Ok(Some(values.into_iter().map(|v| v * PI / 180.0).collect())), + "pi" => Ok(Some(values.into_iter().map(|v| v * PI).collect())), + _ => Err(format!("Unsupported angle unit: {unit}")), + } +} + +/// Helper: extract optional metadata from a JSON object. +fn extract_metadata( + obj: &serde_json::Map, +) -> Option> { + obj.get("metadata").and_then(|v| { + if v.is_null() { + None + } else { + serde_json::from_value(v.clone()).ok() + } + }) +} + +impl<'de> Deserialize<'de> for Operation { + fn deserialize(deserializer: D) -> Result + where + D: serde::Deserializer<'de>, + { + use serde::de::Error; + + let val = serde_json::Value::deserialize(deserializer)?; + let obj = val + .as_object() + .ok_or_else(|| D::Error::custom("operation must be a JSON object"))?; + + // Dispatch on the discriminating key + if let Some(qop_val) = obj.get("qop") { + // QuantumOp + let qop = qop_val + .as_str() + .ok_or_else(|| D::Error::custom("qop must be a string"))? + .to_string(); + let angles = obj + .get("angles") + .map_or(Ok(None), convert_angles) + .map_err(D::Error::custom)?; + let args: Vec = obj + .get("args") + .map_or(Ok(vec![]), |v| serde_json::from_value(v.clone())) + .map_err(|e| D::Error::custom(format!("args: {e}")))?; + let returns: Vec<(String, usize)> = obj + .get("returns") + .map_or(Ok(vec![]), |v| serde_json::from_value(v.clone())) + .map_err(|e| D::Error::custom(format!("returns: {e}")))?; + let metadata = extract_metadata(obj); + Ok(Operation::QuantumOp { + qop, + angles, + args, + returns, + metadata, + }) + } else if let Some(cop_val) = obj.get("cop") { + // ClassicalOp + let cop = cop_val + .as_str() + .ok_or_else(|| D::Error::custom("cop must be a string"))? + .to_string(); + let args: Vec = obj + .get("args") + .map_or(Ok(vec![]), |v| serde_json::from_value(v.clone())) + .map_err(|e| D::Error::custom(format!("args: {e}")))?; + let returns: Vec = obj + .get("returns") + .map_or(Ok(vec![]), |v| serde_json::from_value(v.clone())) + .map_err(|e| D::Error::custom(format!("returns: {e}")))?; + let metadata = extract_metadata(obj); + let function: Option = obj + .get("function") + .and_then(|v| v.as_str().map(String::from)); + Ok(Operation::ClassicalOp { + cop, + args, + returns, + metadata, + function, + }) + } else if let Some(block_val) = obj.get("block") { + // Block + let block = block_val + .as_str() + .ok_or_else(|| D::Error::custom("block must be a string"))? + .to_string(); + let ops: Vec = obj + .get("ops") + .map_or(Ok(vec![]), |v| serde_json::from_value(v.clone())) + .map_err(|e| D::Error::custom(format!("ops: {e}")))?; + let condition: Option = obj + .get("condition") + .filter(|v| !v.is_null()) + .map(|v| serde_json::from_value(v.clone())) + .transpose() + .map_err(|e| D::Error::custom(format!("condition: {e}")))?; + let true_branch: Option> = obj + .get("true_branch") + .filter(|v| !v.is_null()) + .map(|v| serde_json::from_value(v.clone())) + .transpose() + .map_err(|e| D::Error::custom(format!("true_branch: {e}")))?; + let false_branch: Option> = obj + .get("false_branch") + .filter(|v| !v.is_null()) + .map(|v| serde_json::from_value(v.clone())) + .transpose() + .map_err(|e| D::Error::custom(format!("false_branch: {e}")))?; + let metadata = extract_metadata(obj); + Ok(Operation::Block { + block, + ops, + condition, + true_branch, + false_branch, + metadata, + }) + } else if let Some(mop_val) = obj.get("mop") { + // MachineOp + let mop = mop_val + .as_str() + .ok_or_else(|| D::Error::custom("mop must be a string"))? + .to_string(); + let args: Option> = obj.get("args").and_then(|v| { + if v.is_null() { + None + } else { + serde_json::from_value(v.clone()).ok() + } + }); + let duration: Option<(f64, String)> = obj.get("duration").and_then(|v| { + if v.is_null() { + None + } else { + serde_json::from_value(v.clone()).ok() + } + }); + let metadata = extract_metadata(obj); + Ok(Operation::MachineOp { + mop, + args, + duration, + metadata, + }) + } else if let Some(meta_val) = obj.get("meta") { + // MetaInstruction + let meta = meta_val + .as_str() + .ok_or_else(|| D::Error::custom("meta must be a string"))? + .to_string(); + let args: Vec<(String, usize)> = obj + .get("args") + .map_or(Ok(vec![]), |v| serde_json::from_value(v.clone())) + .map_err(|e| D::Error::custom(format!("args: {e}")))?; + let metadata = extract_metadata(obj); + Ok(Operation::MetaInstruction { + meta, + args, + metadata, + }) + } else if let Some(comment_val) = obj.get("//") { + // Comment + let comment = comment_val + .as_str() + .ok_or_else(|| D::Error::custom("comment must be a string"))? + .to_string(); + Ok(Operation::Comment { comment }) + } else if let Some(data_val) = obj.get("data") { + let data = data_val + .as_str() + .ok_or_else(|| D::Error::custom("data must be a string"))? + .to_string(); + if obj.contains_key("variables") { + // DataExport + let variables: Vec = serde_json::from_value(obj["variables"].clone()) + .map_err(|e| D::Error::custom(format!("variables: {e}")))?; + Ok(Operation::DataExport { data, variables }) + } else { + // VariableDefinition + let data_type: String = obj + .get("data_type") + .and_then(|v| v.as_str()) + .ok_or_else(|| D::Error::custom("missing data_type"))? + .to_string(); + let variable: String = obj + .get("variable") + .and_then(|v| v.as_str()) + .ok_or_else(|| D::Error::custom("missing variable"))? + .to_string(); + let size: Option = + obj.get("size").and_then(|v| v.as_u64().map(|n| n as usize)); + Ok(Operation::VariableDefinition { + data, + data_type, + variable, + size, + }) + } + } else { + Err(D::Error::custom(format!( + "unknown operation: no recognized key (qop, cop, block, mop, meta, //, data) found in {:?}", + obj.keys().collect::>() + ))) + } + } } /// Represents an argument to a quantum operation @@ -148,25 +371,133 @@ pub fn infer_size(data_type: &str, explicit_size: Option) -> usize { digits.parse().unwrap_or(0) } -/// Custom deserializer to convert angles to radians -fn deserialize_angles_to_radians<'de, D>(deserializer: D) -> Result>, D::Error> -where - D: Deserializer<'de>, -{ - // First, deserialize as Option<(Vec, String)> - Option::<(Vec, String)>::deserialize(deserializer)?.map_or(Ok(None), |(values, unit)| { - // Convert to radians based on unit - let converted_values = match unit.as_str() { - "rad" => values, // Already in radians - "deg" => values.into_iter().map(|v| v * PI / 180.0).collect(), - "pi" => values.into_iter().map(|v| v * PI).collect(), - _ => { - return Err(serde::de::Error::custom(format!( - "Unsupported angle unit: {unit}" - ))); +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_parse_qparallel_with_angles() { + let json = r#"{ + "format": "PHIR/JSON", + "version": "0.1.0", + "metadata": {}, + "ops": [ + {"data": "qvar_define", "data_type": "qubits", "variable": "q", "size": 2}, + {"data": "cvar_define", "data_type": "u32", "variable": "m", "size": 2}, + {"qop": "RZ", "angles": [[1.0], "pi"], "args": [["q", 0], ["q", 1]]}, + {"block": "qparallel", "ops": [ + {"qop": "R1XY", "angles": [[0.5, 0.5], "pi"], "args": [["q", 0]]}, + {"qop": "R1XY", "angles": [[1.5, 0.5], "pi"], "args": [["q", 1]]} + ]}, + {"qop": "RZZ", "angles": [[0.5], "pi"], "args": [[["q", 0], ["q", 1]]]}, + {"qop": "Measure", "args": [["q", 0], ["q", 1]], "returns": [["m", 0], ["m", 1]]} + ] + }"#; + let program: PHIRProgram = serde_json::from_str(json).expect("should parse"); + assert_eq!(program.ops.len(), 6); + + // Verify angles were converted to radians (pi units) + if let Operation::QuantumOp { angles, .. } = &program.ops[2] { + let a = angles.as_ref().unwrap(); + assert!((a[0] - PI).abs() < 1e-10, "RZ angle should be pi"); + } else { + panic!("Expected QuantumOp"); + } + + // Verify inner ops of qparallel block + if let Operation::Block { ops, .. } = &program.ops[3] { + assert_eq!(ops.len(), 2); + if let Operation::QuantumOp { qop, angles, .. } = &ops[0] { + assert_eq!(qop, "R1XY"); + let a = angles.as_ref().unwrap(); + assert_eq!(a.len(), 2); + assert!((a[0] - 0.5 * PI).abs() < 1e-10); + assert!((a[1] - 0.5 * PI).abs() < 1e-10); + } else { + panic!("Expected QuantumOp inside block"); } - }; + } else { + panic!("Expected Block"); + } + } - Ok(Some(converted_values)) - }) + #[test] + fn test_parse_bell_qparallel_compact() { + // Simulate what Python json.dumps produces (compact, single-line) + let json = r#"{"format": "PHIR/JSON", "version": "0.1.0", "metadata": {"source": "pytket-phir v0.2.0", "strict_parallelism": "true"}, "ops": [{"data": "qvar_define", "data_type": "qubits", "variable": "q", "size": 2}, {"data": "cvar_define", "data_type": "u32", "variable": "m", "size": 2}, {"qop": "RZ", "angles": [[1.0], "pi"], "args": [["q", 0], ["q", 1]]}, {"block": "qparallel", "ops": [{"qop": "R1XY", "angles": [[0.5, 0.5], "pi"], "args": [["q", 0]]}, {"qop": "R1XY", "angles": [[1.5, 0.5], "pi"], "args": [["q", 1]]}]}, {"qop": "RZ", "angles": [[1.0], "pi"], "args": [["q", 0]]}, {"qop": "RZZ", "angles": [[0.5], "pi"], "args": [[["q", 0], ["q", 1]]]}, {"block": "qparallel", "ops": [{"qop": "RZ", "angles": [[1.5], "pi"], "args": [["q", 0]]}, {"qop": "RZ", "angles": [[0.5], "pi"], "args": [["q", 1]]}]}, {"qop": "R1XY", "angles": [[1.5, 0.5], "pi"], "args": [["q", 1]]}, {"qop": "Measure", "args": [["q", 0], ["q", 1]], "returns": [["m", 0], ["m", 1]]}]}"#; + let program: PHIRProgram = serde_json::from_str(json).expect("should parse"); + assert_eq!(program.ops.len(), 9); + } + + #[test] + fn test_angle_units() { + // Test all three angle unit types + let json = r#"{ + "format": "PHIR/JSON", "version": "0.1.0", "metadata": {}, + "ops": [ + {"data": "qvar_define", "data_type": "qubits", "variable": "q", "size": 1}, + {"qop": "RZ", "angles": [[1.5707963267948966], "rad"], "args": [["q", 0]]}, + {"qop": "RZ", "angles": [[90.0], "deg"], "args": [["q", 0]]}, + {"qop": "RZ", "angles": [[0.5], "pi"], "args": [["q", 0]]} + ] + }"#; + let program: PHIRProgram = serde_json::from_str(json).expect("should parse"); + + // All three should produce the same angle (pi/2) + for i in 1..=3 { + if let Operation::QuantumOp { angles, .. } = &program.ops[i] { + let a = angles.as_ref().unwrap(); + assert!( + (a[0] - std::f64::consts::FRAC_PI_2).abs() < 1e-10, + "op {i}: expected pi/2, got {}", + a[0] + ); + } + } + } + + #[test] + fn test_no_angles() { + let json = r#"{ + "format": "PHIR/JSON", "version": "0.1.0", "metadata": {}, + "ops": [ + {"data": "qvar_define", "data_type": "qubits", "variable": "q", "size": 1}, + {"qop": "H", "args": [["q", 0]]}, + {"qop": "Measure", "args": [["q", 0]], "returns": [["m", 0]]} + ] + }"#; + let program: PHIRProgram = serde_json::from_str(json).expect("should parse"); + if let Operation::QuantumOp { angles, .. } = &program.ops[1] { + assert!(angles.is_none()); + } + } + + #[test] + fn test_comment() { + let json = r#"{ + "format": "PHIR/JSON", "version": "0.1.0", "metadata": {}, + "ops": [{"//": "this is a comment"}] + }"#; + let program: PHIRProgram = serde_json::from_str(json).expect("should parse"); + if let Operation::Comment { comment } = &program.ops[0] { + assert_eq!(comment, "this is a comment"); + } else { + panic!("Expected Comment"); + } + } + + #[test] + fn test_data_export() { + let json = r#"{ + "format": "PHIR/JSON", "version": "0.1.0", "metadata": {}, + "ops": [{"data": "cvar_export", "variables": ["m", "n"]}] + }"#; + let program: PHIRProgram = serde_json::from_str(json).expect("should parse"); + if let Operation::DataExport { data, variables } = &program.ops[0] { + assert_eq!(data, "cvar_export"); + assert_eq!(variables, &["m", "n"]); + } else { + panic!("Expected DataExport"); + } + } } diff --git a/crates/pecos-phir/src/execution/processor.rs b/crates/pecos-phir/src/execution/processor.rs index a1a1df789..a9769d355 100644 --- a/crates/pecos-phir/src/execution/processor.rs +++ b/crates/pecos-phir/src/execution/processor.rs @@ -505,8 +505,8 @@ impl PhirProcessor { self.process_binary_int_op( instruction, "div", - |a, b| if b == 0 { 0 } else { a / b }, - |a, b| if b == 0 { 0 } else { a / b }, + |a, b| a.checked_div(b).unwrap_or(0), + |a, b| a.checked_div(b).unwrap_or(0), ); Ok(()) } @@ -1209,49 +1209,45 @@ impl PhirProcessor { instruction: &crate::phir::Instruction, ) { match mem_op { - MemoryOp::Alloc(alloc_type) => { - if !instruction.results.is_empty() { - let ptr_id = instruction.results[0].id; - let default = match alloc_type { - #[allow(clippy::match_same_arms)] - crate::ops::AllocType::Scalar(ty) => match ty { - crate::types::Type::Int( - crate::types::IntWidth::I8 - | crate::types::IntWidth::I16 - | crate::types::IntWidth::I32, - ) => TypedValue::I32(0), - crate::types::Type::Int(_) => TypedValue::I64(0), - crate::types::Type::UInt( - crate::types::IntWidth::I8 - | crate::types::IntWidth::I16 - | crate::types::IntWidth::I32, - ) => TypedValue::U32(0), - crate::types::Type::UInt(_) => TypedValue::U64(0), - crate::types::Type::Bool => TypedValue::Bool(false), - crate::types::Type::Float(_) => TypedValue::F64(0.0), - _ => TypedValue::I64(0), - }, + MemoryOp::Alloc(alloc_type) if !instruction.results.is_empty() => { + let ptr_id = instruction.results[0].id; + let default = match alloc_type { + #[allow(clippy::match_same_arms)] + crate::ops::AllocType::Scalar(ty) => match ty { + crate::types::Type::Int( + crate::types::IntWidth::I8 + | crate::types::IntWidth::I16 + | crate::types::IntWidth::I32, + ) => TypedValue::I32(0), + crate::types::Type::Int(_) => TypedValue::I64(0), + crate::types::Type::UInt( + crate::types::IntWidth::I8 + | crate::types::IntWidth::I16 + | crate::types::IntWidth::I32, + ) => TypedValue::U32(0), + crate::types::Type::UInt(_) => TypedValue::U64(0), + crate::types::Type::Bool => TypedValue::Bool(false), + crate::types::Type::Float(_) => TypedValue::F64(0.0), _ => TypedValue::I64(0), - }; - self.memory.insert(ptr_id, default); - } + }, + _ => TypedValue::I64(0), + }; + self.memory.insert(ptr_id, default); } - MemoryOp::Load => { - if !instruction.operands.is_empty() && !instruction.results.is_empty() { - let ptr_id = instruction.operands[0].id; - let res_id = instruction.results[0].id; - if let Some(val) = self.memory.get(&ptr_id) { - self.ssa_values.insert(res_id, val.clone()); - } + MemoryOp::Load + if !instruction.operands.is_empty() && !instruction.results.is_empty() => + { + let ptr_id = instruction.operands[0].id; + let res_id = instruction.results[0].id; + if let Some(val) = self.memory.get(&ptr_id) { + self.ssa_values.insert(res_id, val.clone()); } } - MemoryOp::Store => { - if instruction.operands.len() >= 2 { - let val_id = instruction.operands[0].id; - let ptr_id = instruction.operands[1].id; - if let Some(val) = self.ssa_values.get(&val_id) { - self.memory.insert(ptr_id, val.clone()); - } + MemoryOp::Store if instruction.operands.len() >= 2 => { + let val_id = instruction.operands[0].id; + let ptr_id = instruction.operands[1].id; + if let Some(val) = self.ssa_values.get(&val_id) { + self.memory.insert(ptr_id, val.clone()); } } _ => {} // Skip other memory ops diff --git a/crates/pecos-phir/src/hugr_parser.rs b/crates/pecos-phir/src/hugr_parser.rs index eb91fb6ce..f4521fba9 100644 --- a/crates/pecos-phir/src/hugr_parser.rs +++ b/crates/pecos-phir/src/hugr_parser.rs @@ -517,16 +517,16 @@ impl HugrToPhirConverter { } // Step 1: Emit all Measure instructions - let mut meas_results: Vec<(SSAValue, usize)> = Vec::with_capacity(measurements.len()); + let mut meas_ids: Vec<(SSAValue, usize)> = Vec::with_capacity(measurements.len()); for &(qubit_ssa, bit_idx) in measurements { - let meas_result = self.fresh_ssa(); + let meas_id = self.fresh_ssa(); block.add_instruction(Instruction::new( Operation::Quantum(QuantumOp::Measure), vec![qubit_ssa], - vec![meas_result], + vec![meas_id], vec![Type::Bit], )); - meas_results.push((meas_result, bit_idx)); + meas_ids.push((meas_id, bit_idx)); } // Step 2: Combine bits into a single integer and emit Result @@ -541,7 +541,7 @@ impl HugrToPhirConverter { let mut accum = zero_ssa; - for &(meas_ssa, bit_idx) in &meas_results { + for &(meas_ssa, bit_idx) in &meas_ids { // Bitcast measurement bit to i64 let cast_ssa = self.fresh_ssa(); block.add_instruction(Instruction::new( diff --git a/crates/pecos-phir/src/traits.rs b/crates/pecos-phir/src/traits.rs index d7df8b7b1..0089c6871 100644 --- a/crates/pecos-phir/src/traits.rs +++ b/crates/pecos-phir/src/traits.rs @@ -296,10 +296,8 @@ impl OperationInterface for Instruction { return Err("Measure operation must produce at least one result".to_string()); } } - Operation::ControlFlow(ControlFlowOp::Loop(_)) => { - if self.regions.is_empty() { - return Err("Loop operation must have at least one region".to_string()); - } + Operation::ControlFlow(ControlFlowOp::Loop(_)) if self.regions.is_empty() => { + return Err("Loop operation must have at least one region".to_string()); } _ => {} } diff --git a/crates/pecos-pymatching/Cargo.toml b/crates/pecos-pymatching/Cargo.toml index 8d88bc287..bbabfe235 100644 --- a/crates/pecos-pymatching/Cargo.toml +++ b/crates/pecos-pymatching/Cargo.toml @@ -10,6 +10,7 @@ license.workspace = true keywords.workspace = true categories.workspace = true description = "PyMatching MWPM decoder for PECOS" +links = "pymatching-pecos" [dependencies] pecos-decoder-core.workspace = true diff --git a/crates/pecos-pymatching/build_pymatching.rs b/crates/pecos-pymatching/build_pymatching.rs index 7dc42c4e2..640da3024 100644 --- a/crates/pecos-pymatching/build_pymatching.rs +++ b/crates/pecos-pymatching/build_pymatching.rs @@ -60,6 +60,16 @@ pub fn build() -> Result<()> { let pymatching_dir = ensure_dep_ready("pymatching", &manifest)?; let stim_dir = ensure_dep_ready("stim", &manifest)?; + // Export paths so downstream crates (e.g., pecos-chromobius) can include + // PyMatching/Stim headers and link against our compiled objects without + // compiling their own copy. + let pymatching_src = pymatching_dir.join("src"); + let stim_src = stim_dir.join("src"); + println!("cargo:pymatching_include={}", pymatching_src.display()); + println!("cargo:stim_include={}", stim_src.display()); + println!("cargo:stim_dir={}", stim_dir.display()); + println!("cargo:lib_dir={}", out_dir.display()); + // Build using cxx build_cxx_bridge(&pymatching_dir, &stim_dir)?; @@ -180,7 +190,6 @@ fn collect_pymatching_sources(pymatching_src_dir: &Path) -> Result> sources.extend([ driver_dir.join("user_graph.cc"), driver_dir.join("mwpm_decoding.cc"), - driver_dir.join("io.cc"), ]); // Matcher files diff --git a/crates/pecos-pymatching/include/pymatching_bridge.h b/crates/pecos-pymatching/include/pymatching_bridge.h index a72d10602..a76c20163 100644 --- a/crates/pecos-pymatching/include/pymatching_bridge.h +++ b/crates/pecos-pymatching/include/pymatching_bridge.h @@ -20,7 +20,8 @@ class PyMatchingGraph { // Constructors PyMatchingGraph(size_t num_nodes); PyMatchingGraph(size_t num_nodes, size_t num_observables); - static std::unique_ptr from_dem(const std::string& dem_string); + static std::unique_ptr from_dem( + const std::string& dem_string, bool enable_correlations = false); ~PyMatchingGraph(); // Edge management @@ -104,6 +105,8 @@ std::unique_ptr create_pymatching_graph_with_observables( size_t num_nodes, size_t num_observables); std::unique_ptr create_pymatching_graph_from_dem( const rust::Str dem_string); +std::unique_ptr create_pymatching_graph_from_dem_with_correlations( + const rust::Str dem_string, bool enable_correlations); void add_edge( PyMatchingGraph& graph, diff --git a/crates/pecos-pymatching/pecos.toml b/crates/pecos-pymatching/pecos.toml index 16daa358c..635349187 100644 --- a/crates/pecos-pymatching/pecos.toml +++ b/crates/pecos-pymatching/pecos.toml @@ -4,13 +4,13 @@ version = 1 [dependencies.pymatching] -version = "2b72b2c558eec678656da20ab6c358aa123fb664" -url = "https://github.com/oscarhiggott/PyMatching/archive/2b72b2c558eec678656da20ab6c358aa123fb664.tar.gz" -sha256 = "1470520b66ad7899f85020664aeeadfc6e2967f0b5e19ad205829968b845cd70" +version = "c60642af5a5b342d633e2e2b818b9fdb9696e828" +url = "https://github.com/oscarhiggott/PyMatching/archive/c60642af5a5b342d633e2e2b818b9fdb9696e828.tar.gz" +sha256 = "c9e775619a791a3a0a58073447fd3f2c61a9804ecaa716fd753ef8f0a81783de" description = "MWPM decoder" [dependencies.stim] -version = "bd60b73525fd5a9b30839020eb7554ad369e4337" -url = "https://github.com/quantumlib/Stim/archive/bd60b73525fd5a9b30839020eb7554ad369e4337.tar.gz" -sha256 = "2a4be24295ce3018d79e08369b31e401a2d33cd8b3a75675d57dac3afd9de37d" +version = "213275795e49027772bea7c610b6aac3a80583e1" +url = "https://github.com/quantumlib/Stim/archive/213275795e49027772bea7c610b6aac3a80583e1.tar.gz" +sha256 = "b63c4ae94494a8819d440757776cf80a829ec1e30454fa7c9b0f670e981938ab" description = "Stabilizer simulator for QEC" diff --git a/crates/pecos-pymatching/src/bridge.cpp b/crates/pecos-pymatching/src/bridge.cpp index 30ddc3e42..7bbef999d 100644 --- a/crates/pecos-pymatching/src/bridge.cpp +++ b/crates/pecos-pymatching/src/bridge.cpp @@ -15,7 +15,6 @@ // PyMatching includes #include "pymatching/sparse_blossom/driver/user_graph.h" #include "pymatching/sparse_blossom/driver/mwpm_decoding.h" -#include "pymatching/sparse_blossom/driver/io.h" #include "pymatching/sparse_blossom/search/search_graph.h" #include "pymatching/rand/rand_gen.h" @@ -32,6 +31,7 @@ class PyMatchingGraph::Impl { std::unique_ptr mwpm_; pm::SearchFlooder* search_flooder_ = nullptr; double normalising_constant_ = 1.0; + bool enable_correlations_ = false; // Constructor Impl(size_t num_nodes, size_t num_observables) { @@ -39,7 +39,7 @@ class PyMatchingGraph::Impl { } // Initialize MWPM decoder when needed - void ensure_mwpm(bool include_search_graph = false) { + void ensure_mwpm(bool include_search_graph) { if (!mwpm_ || (include_search_graph && !search_flooder_)) { normalising_constant_ = user_graph_->get_edge_weight_normalising_constant(pm::NUM_DISTINCT_WEIGHTS); if (normalising_constant_ == 0) { @@ -73,12 +73,14 @@ PyMatchingGraph::PyMatchingGraph(size_t num_nodes, size_t num_observables) PyMatchingGraph::~PyMatchingGraph() = default; -std::unique_ptr PyMatchingGraph::from_dem(const std::string& dem_string) { +std::unique_ptr PyMatchingGraph::from_dem( + const std::string& dem_string, bool enable_correlations) { try { auto dem = stim::DetectorErrorModel(dem_string.c_str()); // Create user graph from DEM - auto user_graph = pm::detector_error_model_to_user_graph(dem); + auto user_graph = pm::detector_error_model_to_user_graph( + dem, enable_correlations, pm::NUM_DISTINCT_WEIGHTS); // Create PyMatchingGraph and move the user graph auto graph = std::make_unique( @@ -88,6 +90,7 @@ std::unique_ptr PyMatchingGraph::from_dem(const std::string& de // Replace the default user graph with the one from DEM graph->pimpl_->user_graph_ = std::make_unique(std::move(user_graph)); + graph->pimpl_->enable_correlations_ = enable_correlations; return graph; } catch (const std::exception& e) { @@ -305,7 +308,7 @@ bool PyMatchingGraph::is_boundary_node(size_t node) const { ExtendedMatchingResult PyMatchingGraph::decode_detection_events_64( const rust::Slice detection_events) { - pimpl_->ensure_mwpm(); + pimpl_->ensure_mwpm(pimpl_->enable_correlations_); // Convert detection events to vector of indices std::vector detections; @@ -316,7 +319,8 @@ ExtendedMatchingResult PyMatchingGraph::decode_detection_events_64( } try { - auto result = pm::decode_detection_events_for_up_to_64_observables(*pimpl_->mwpm_, detections); + auto result = pm::decode_detection_events_for_up_to_64_observables( + *pimpl_->mwpm_, detections, pimpl_->enable_correlations_); pimpl_->reset_mwpm(); ExtendedMatchingResult ext_result; @@ -338,7 +342,7 @@ ExtendedMatchingResult PyMatchingGraph::decode_detection_events_64( ExtendedMatchingResult PyMatchingGraph::decode_detection_events_extended( const rust::Slice detection_events) { - pimpl_->ensure_mwpm(); + pimpl_->ensure_mwpm(pimpl_->enable_correlations_); // Convert detection events std::vector detections; @@ -353,7 +357,8 @@ ExtendedMatchingResult PyMatchingGraph::decode_detection_events_extended( std::vector obs_vec(num_obs, 0); pm::total_weight_int weight = 0; - pm::decode_detection_events(*pimpl_->mwpm_, detections, obs_vec.data(), weight); + pm::decode_detection_events( + *pimpl_->mwpm_, detections, obs_vec.data(), weight, pimpl_->enable_correlations_); pimpl_->reset_mwpm(); ExtendedMatchingResult result; @@ -373,7 +378,7 @@ ExtendedMatchingResult PyMatchingGraph::decode_detection_events_extended( rust::Vec PyMatchingGraph::decode_to_matched_pairs( const rust::Slice detection_events) { - pimpl_->ensure_mwpm(); + pimpl_->ensure_mwpm(pimpl_->enable_correlations_); // Convert detection events std::vector detections; @@ -408,7 +413,7 @@ rust::Vec PyMatchingGraph::decode_to_matched_pairs( rust::Vec PyMatchingGraph::decode_to_edges( const rust::Slice detection_events) { - pimpl_->ensure_mwpm(); + pimpl_->ensure_mwpm(pimpl_->enable_correlations_); // Convert detection events std::vector detections; @@ -450,7 +455,7 @@ BatchDecodingResult PyMatchingGraph::decode_batch( bool bit_packed_shots, bool bit_packed_predictions) { - pimpl_->ensure_mwpm(); + pimpl_->ensure_mwpm(pimpl_->enable_correlations_); BatchDecodingResult result; result.predictions = rust::Vec(); @@ -493,7 +498,8 @@ BatchDecodingResult PyMatchingGraph::decode_batch( // Decode if (num_obs <= 64) { - auto res = pm::decode_detection_events_for_up_to_64_observables(*pimpl_->mwpm_, detections); + auto res = pm::decode_detection_events_for_up_to_64_observables( + *pimpl_->mwpm_, detections, pimpl_->enable_correlations_); if (bit_packed_predictions) { // Pack obs_mask into bytes @@ -518,7 +524,8 @@ BatchDecodingResult PyMatchingGraph::decode_batch( std::vector obs_vec(num_obs, 0); pm::total_weight_int weight = 0; - pm::decode_detection_events(*pimpl_->mwpm_, detections, obs_vec.data(), weight); + pm::decode_detection_events( + *pimpl_->mwpm_, detections, obs_vec.data(), weight, pimpl_->enable_correlations_); if (bit_packed_predictions) { // Pack observables into bytes @@ -678,7 +685,12 @@ std::unique_ptr create_pymatching_graph_with_observables( } std::unique_ptr create_pymatching_graph_from_dem(const rust::Str dem_string) { - return PyMatchingGraph::from_dem(std::string(dem_string)); + return PyMatchingGraph::from_dem(std::string(dem_string), false); +} + +std::unique_ptr create_pymatching_graph_from_dem_with_correlations( + const rust::Str dem_string, bool enable_correlations) { + return PyMatchingGraph::from_dem(std::string(dem_string), enable_correlations); } void add_edge( diff --git a/crates/pecos-pymatching/src/bridge.rs b/crates/pecos-pymatching/src/bridge.rs index f267743da..b2becdc86 100644 --- a/crates/pecos-pymatching/src/bridge.rs +++ b/crates/pecos-pymatching/src/bridge.rs @@ -73,6 +73,19 @@ pub(crate) mod ffi { fn create_pymatching_graph_from_dem(dem_string: &str) -> Result>; + /// Create a `PyMatching` graph from a DEM string with correlation support. + /// + /// When `enable_correlations` is true, the decoder tracks edge correlations + /// during graph construction and uses them during decoding. + /// + /// # Errors + /// + /// Returns a CXX exception if the DEM string is malformed. + fn create_pymatching_graph_from_dem_with_correlations( + dem_string: &str, + enable_correlations: bool, + ) -> Result>; + // ===== Edge Management ===== /// Add an edge between two nodes. diff --git a/crates/pecos-pymatching/src/core_traits.rs b/crates/pecos-pymatching/src/core_traits.rs index 708aa4042..8a96c2b16 100644 --- a/crates/pecos-pymatching/src/core_traits.rs +++ b/crates/pecos-pymatching/src/core_traits.rs @@ -7,8 +7,8 @@ use crate::decoder::{CheckMatrix, CheckMatrixConfig, DecodingResult, PyMatchingD use crate::errors::PyMatchingError; use ndarray::{ArrayView1, ArrayView2}; use pecos_decoder_core::{ - BatchDecoder, CheckMatrixDecoder, Decoder, DecodingStats, DemDecoder, DetailedDecoder, - MatchedEdge, MatchedPair as CoreMatchedPair, + BatchDecoder, CheckMatrixDecoder, Decoder, DecoderError, DecodingStats, DemDecoder, + DetailedDecoder, MatchedEdge, MatchedPair as CoreMatchedPair, ObservableDecoder, }; /// Implement the core Decoder trait for `PyMatchingDecoder` @@ -184,6 +184,52 @@ impl DetailedDecoder for PyMatchingDecoder { } } +/// Implement `ObservableDecoder` for `PyMatchingDecoder`. +/// +/// Converts the observable vector to a bitmask for the sample+decode loop. +impl ObservableDecoder for PyMatchingDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + let result = self + .decode(syndrome) + .map_err(|e| DecoderError::DecodingFailed(e.to_string()))?; + let mut mask = 0u64; + for (i, &v) in result.observable.iter().enumerate() { + if v != 0 { + mask |= 1 << i; + } + } + Ok(mask) + } + + fn decode_batch_to_observables( + &mut self, + shots: &[u8], + num_shots: usize, + num_detectors: usize, + ) -> Result, DecoderError> { + use crate::decoder::BatchConfig; + let config = BatchConfig { + bit_packed_input: false, + bit_packed_output: true, + return_weights: false, + }; + let result = self + .decode_batch_with_config(shots, num_shots, num_detectors, config) + .map_err(|e| DecoderError::DecodingFailed(e.to_string()))?; + + // Convert per-shot bit-packed predictions to u64 masks. + let mut masks = Vec::with_capacity(num_shots); + for pred in &result.predictions { + let mut mask = 0u64; + for (byte_idx, &byte) in pred.iter().enumerate() { + mask |= u64::from(byte) << (byte_idx * 8); + } + masks.push(mask); + } + Ok(masks) + } +} + #[cfg(test)] mod tests { use super::*; diff --git a/crates/pecos-pymatching/src/decoder.rs b/crates/pecos-pymatching/src/decoder.rs index 62b98c0ee..f63a67d6d 100644 --- a/crates/pecos-pymatching/src/decoder.rs +++ b/crates/pecos-pymatching/src/decoder.rs @@ -535,6 +535,31 @@ impl PyMatchingDecoder { Ok(Self { graph, config }) } + /// Create a decoder from a DEM string with correlation support + /// + /// When `enable_correlations` is true, the decoder tracks edge correlations + /// during graph construction and uses them during decoding. + /// + /// # Errors + /// Returns an error if the DEM string is invalid or cannot be parsed. + pub fn from_dem_with_correlations(dem_string: &str, enable_correlations: bool) -> Result { + let graph = ffi::create_pymatching_graph_from_dem_with_correlations( + dem_string, + enable_correlations, + )?; + + let num_nodes = ffi::pymatching_get_num_nodes(&graph); + let num_observables = ffi::pymatching_get_num_observables(&graph); + + let config = PyMatchingConfig { + num_neighbours: None, + num_nodes: Some(num_nodes), + num_observables, + }; + + Ok(Self { graph, config }) + } + /// Create a decoder from a check matrix /// /// The check matrix should be in sparse format where: @@ -1553,11 +1578,7 @@ impl From for BatchDecodingResult { // The result from FFI is already in the requested format // We just need to reshape it by shots let num_shots = result.weights.len(); - let bytes_per_shot = if num_shots > 0 { - result.predictions.len() / num_shots - } else { - 0 - }; + let bytes_per_shot = result.predictions.len().checked_div(num_shots).unwrap_or(0); let predictions = if bytes_per_shot > 0 { result diff --git a/crates/pecos-qasm/src/engine.rs b/crates/pecos-qasm/src/engine.rs index 14c24d148..1e752de79 100644 --- a/crates/pecos-qasm/src/engine.rs +++ b/crates/pecos-qasm/src/engine.rs @@ -623,7 +623,8 @@ impl QASMEngine { | GateType::MeasCrosstalkLocalPayload | GateType::MeasCrosstalkGlobalPayload | GateType::QFree - | GateType::Custom => Ok(()), // No-op gates (QFree is just a marker, Custom is a placeholder) + | GateType::Custom + | GateType::PauliOperatorMeta => Ok(()), // No-op gates GateType::X | GateType::Z | GateType::Y @@ -1591,10 +1592,7 @@ impl ControlEngine for QASMEngine { ) -> Result, PecosError> { debug!("QASMEngine::continue_processing() called"); - let measurement_count = measurements - .outcomes() - .map(|outcomes| outcomes.len()) - .unwrap_or(0); + let measurement_count = measurements.outcomes().map_or(0, |outcomes| outcomes.len()); debug!("Received {measurement_count} measurements"); debug!("Processing measurement results"); diff --git a/crates/pecos-qasm/src/qasm_to_phir.rs b/crates/pecos-qasm/src/qasm_to_phir.rs index ed55a47a4..576e0404a 100644 --- a/crates/pecos-qasm/src/qasm_to_phir.rs +++ b/crates/pecos-qasm/src/qasm_to_phir.rs @@ -228,14 +228,14 @@ impl Converter { Vec::with_capacity(measurements.len()); for (qubit_ssa, reg_name, bit_idx) in measurements { - let meas_result = self.new_ssa(); + let meas_id = self.new_ssa(); block.add_instruction(Instruction::new( Operation::Quantum(QuantumOp::Measure), vec![*qubit_ssa], - vec![meas_result], + vec![meas_id], vec![Type::Bit], )); - measure_results.push((meas_result, reg_name.clone(), *bit_idx)); + measure_results.push((meas_id, reg_name.clone(), *bit_idx)); } // Step 2: Group by register and combine bits diff --git a/crates/pecos-qasm/tests/features/constant_folding_test.rs b/crates/pecos-qasm/tests/features/constant_folding_test.rs index aacedbb33..7e26b45cd 100644 --- a/crates/pecos-qasm/tests/features/constant_folding_test.rs +++ b/crates/pecos-qasm/tests/features/constant_folding_test.rs @@ -90,10 +90,8 @@ fn test_integer_constant_folding() { if value == "1" { // Condition is true, operation should be X match &**operation { - pecos_qasm::ast::Operation::Gate { name, .. } => { - if name == "x" { - x_count += 1; - } + pecos_qasm::ast::Operation::Gate { name, .. } if name == "x" => { + x_count += 1; } pecos_qasm::ast::Operation::NativeGate(gate) => { if matches!(gate.gate_type, pecos_engines::GateType::X) { @@ -104,10 +102,8 @@ fn test_integer_constant_folding() { } } } - pecos_qasm::ast::Operation::Gate { name, .. } => { - if name == "y" { - y_count += 1; - } + pecos_qasm::ast::Operation::Gate { name, .. } if name == "y" => { + y_count += 1; } _ => {} } @@ -182,12 +178,10 @@ fn test_complex_expression_folding() { } pecos_qasm::ast::Operation::Gate { name, parameters, .. - } => { - if name == "rz" { - assert_eq!(parameters.len(), 1); - // (pi/2 + pi/2) * sin(pi/2) = pi * 1 = pi - assert!((parameters[0] - std::f64::consts::PI).abs() < 1e-10); - } + } if name == "rz" => { + assert_eq!(parameters.len(), 1); + // (pi/2 + pi/2) * sin(pi/2) = pi * 1 = pi + assert!((parameters[0] - std::f64::consts::PI).abs() < 1e-10); } _ => {} } diff --git a/crates/pecos-qasm/tests/gates/mixed_gates_test.rs b/crates/pecos-qasm/tests/gates/mixed_gates_test.rs index 701b9d49a..66c018b50 100644 --- a/crates/pecos-qasm/tests/gates/mixed_gates_test.rs +++ b/crates/pecos-qasm/tests/gates/mixed_gates_test.rs @@ -172,15 +172,11 @@ fn test_gate_sequence() { for op in &program.operations { match op { - Operation::Gate { name, qubits, .. } => { - if qubits.contains(&3) { - q3_operations.push(name.clone()); - } + Operation::Gate { name, qubits, .. } if qubits.contains(&3) => { + q3_operations.push(name.clone()); } - Operation::NativeGate(gate) => { - if gate.qubits.iter().any(|q| q.0 == 3) { - q3_operations.push(format!("{:?}", gate.gate_type)); - } + Operation::NativeGate(gate) if gate.qubits.iter().any(|q| q.0 == 3) => { + q3_operations.push(format!("{:?}", gate.gate_type)); } _ => {} } @@ -225,19 +221,15 @@ fn test_two_qubit_gates() { for op in &program.operations { match op { - Operation::Gate { name, qubits, .. } => { - if qubits.len() == 2 { - two_qubit_gates.push((name.clone(), qubits[0], qubits[1])); - } + Operation::Gate { name, qubits, .. } if qubits.len() == 2 => { + two_qubit_gates.push((name.clone(), qubits[0], qubits[1])); } - Operation::NativeGate(gate) => { - if gate.qubits.len() == 2 { - two_qubit_gates.push(( - format!("{:?}", gate.gate_type), - gate.qubits[0].0, - gate.qubits[1].0, - )); - } + Operation::NativeGate(gate) if gate.qubits.len() == 2 => { + two_qubit_gates.push(( + format!("{:?}", gate.gate_type), + gate.qubits[0].0, + gate.qubits[1].0, + )); } _ => {} } diff --git a/crates/pecos-qec/Cargo.toml b/crates/pecos-qec/Cargo.toml index f2acb8fee..30a043360 100644 --- a/crates/pecos-qec/Cargo.toml +++ b/crates/pecos-qec/Cargo.toml @@ -15,15 +15,21 @@ readme = "README.md" ndarray.workspace = true pecos-core.workspace = true pecos-decoder-core.workspace = true +pecos-num.workspace = true pecos-quantum.workspace = true pecos-simulators.workspace = true pecos-random.workspace = true rand.workspace = true rand_core.workspace = true rayon.workspace = true +serde_json.workspace = true smallvec.workspace = true thiserror.workspace = true wide.workspace = true +[[example]] +name = "surface_d3_fault_catalog_lookup" +path = "../../examples/surface/d3_fault_catalog_lookup.rs" + [lints] workspace = true diff --git a/crates/pecos-qec/examples/influence_builder_example.rs b/crates/pecos-qec/examples/influence_builder_example.rs index 363b06fe5..0266c42d5 100644 --- a/crates/pecos-qec/examples/influence_builder_example.rs +++ b/crates/pecos-qec/examples/influence_builder_example.rs @@ -3,14 +3,12 @@ //! Pipeline steps: //! 1. Build a syndrome extraction circuit using `DagCircuit` //! 2. Use `InfluenceBuilder` to extract detectors and build influence map -//! 3. Use `NoisySampler` for CPU-based noisy sampling +//! 3. Use `DemSampler` for fast CPU-based noisy sampling //! //! Run with: cargo run --example `influence_builder_example` --release -p pecos-qec use pecos_qec::fault_tolerance::InfluenceBuilder; -use pecos_qec::fault_tolerance::noisy_sampler::{ - NoisySampler, SamplingStatistics, UniformNoiseModel, -}; +use pecos_qec::fault_tolerance::dem_builder::DemSampler; use pecos_quantum::DagCircuit; /// Build a simple repetition code syndrome extraction circuit. @@ -42,7 +40,7 @@ fn build_repetition_code_circuit(num_rounds: usize) -> DagCircuit { } fn main() { - println!("CPU Pipeline Example: Circuit -> Influence Map -> CPU Sampling\n"); + println!("CPU Pipeline Example: Circuit -> Influence Map -> DemSampler\n"); println!("{:=<70}", ""); // ========================================================================= @@ -57,7 +55,7 @@ fn main() { // ========================================================================= // Build influence map with InfluenceBuilder // ========================================================================= - let builder = InfluenceBuilder::new(&circuit).with_logical_z(vec![0, 1, 2]); // Z logical on all data qubits + let builder = InfluenceBuilder::new(&circuit).with_z(&[0, 1, 2]); // Z logical on all data qubits let influence_map = builder.build(); @@ -78,28 +76,24 @@ fn main() { } // ========================================================================= - // Sample with CPU NoisySampler + // Sample with DemSampler // ========================================================================= let p_error = 0.001; // 0.1% error rate per location - let noise_model = UniformNoiseModel::depolarizing(p_error); let seed = 42u64; + let num_locations = influence_map.locations.len(); + let per_location_probs = vec![p_error; num_locations]; - let mut sampler = NoisySampler::new(&influence_map, noise_model, seed); + let sampler = DemSampler::from_influence_map(&influence_map, &per_location_probs); - println!("\n3. Sampling with CPU NoisySampler:"); + println!("\n3. Sampling with DemSampler:"); println!(" Error rate: {p_error}"); + println!(" Mechanisms: {}", sampler.num_mechanisms()); let num_shots = 100_000; let start = std::time::Instant::now(); - let results = sampler.sample(num_shots); + let stats = sampler.sample_statistics(num_shots, seed); let elapsed = start.elapsed(); - // Collect statistics - let mut stats = SamplingStatistics::new(); - for result in &results { - stats.record(result); - } - println!(" Shots: {num_shots}"); println!(" Time: {:.2}ms", elapsed.as_secs_f64() * 1000.0); #[allow(clippy::cast_precision_loss)] @@ -116,7 +110,6 @@ fn main() { " Undetectable error rate: {:.6}%", stats.undetectable_rate() * 100.0 ); - println!(" Avg faults per shot: {:.2}", stats.average_faults()); // ========================================================================= // Compare with different error rates @@ -129,14 +122,9 @@ fn main() { println!(" {:->8} {:->15} {:->15}", "", "", ""); for p in [0.0001, 0.0005, 0.001, 0.002, 0.005] { - let noise = UniformNoiseModel::depolarizing(p); - let mut sampler = NoisySampler::new(&influence_map, noise, seed); - let results = sampler.sample(50_000); - - let mut stats = SamplingStatistics::new(); - for result in &results { - stats.record(result); - } + let probs = vec![p; num_locations]; + let sampler = DemSampler::from_influence_map(&influence_map, &probs); + let stats = sampler.sample_statistics(50_000, seed); println!( " {:>8.4} {:>14.4}% {:>14.4}%", diff --git a/crates/pecos-qec/src/fault_tolerance.rs b/crates/pecos-qec/src/fault_tolerance.rs index b73107f66..e802aff84 100644 --- a/crates/pecos-qec/src/fault_tolerance.rs +++ b/crates/pecos-qec/src/fault_tolerance.rs @@ -18,14 +18,17 @@ //! For a full guide, see `docs/user-guide/fault-tolerance.md`. pub mod circuit_runner; +pub mod correlation; pub mod decoder_integration; pub mod dem_builder; +pub mod fault_sampler; pub mod gadget_checker; pub mod influence_builder; -pub mod noisy_sampler; +pub mod lookup_decoder; pub mod pauli_prop_checker; pub mod propagator; pub mod stabilizer_flip_checker; +pub mod targeted_lookup_decoder; use pecos_core::QubitId; use pecos_core::gate_type::GateType; @@ -53,11 +56,12 @@ pub use pauli_prop_checker::{ has_syndrome, propagate_fault, propagate_faults, }; pub use propagator::{ - DagFaultAnalyzer, DagFaultInfluenceMap, DagPropagator, DagSpacetimeLocation, DetectorId, - Direction, FaultInfluence, FaultInfluenceMap, InfluenceBasedChecker, LogicalId, MeasurementId, - TickFaultAnalyzer, apply_gate, propagate_backward_from_node, propagate_backward_from_tick, - propagate_fault_backward, propagate_observable_backward, propagate_sparse_dag, - propagate_through_circuit, propagate_through_dag, propagate_tick_range, + DagFaultAnalyzer, DagFaultInfluenceMap, DagPropagator, DagSpacetimeLocation, DemOutputKind, + DemOutputMetadata, DetectorId, Direction, FaultInfluence, FaultInfluenceMap, + InfluenceBasedChecker, MeasurementId, TickFaultAnalyzer, TrackedOpId, apply_gate, + propagate_backward_from_node, propagate_backward_from_tick, propagate_fault_backward, + propagate_observable_backward, propagate_sparse_dag, propagate_through_circuit, + propagate_through_dag, propagate_tick_range, }; pub use stabilizer_flip_checker::{ ErrorClass, StabilizerFlipAnalysis, StabilizerFlipChecker, StabilizerFlips, diff --git a/crates/pecos-qec/src/fault_tolerance/correlation.rs b/crates/pecos-qec/src/fault_tolerance/correlation.rs new file mode 100644 index 000000000..7ab4270ab --- /dev/null +++ b/crates/pecos-qec/src/fault_tolerance/correlation.rs @@ -0,0 +1,591 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Detector correlation analysis for DEM validation. +//! +//! Computes k-body detector firing rates from sampled syndromes and +//! compares them between simulation and DEM outputs. This captures +//! both marginal detection rates and the correlated error structure +//! that determines decoding quality. +//! +//! # Flip frequency matrix +//! +//! The pairwise flip frequency matrix `M` for `n` detectors: +//! - `M[i][i]` = P(detector i fires) (marginal rate) +//! - `M[i][j]` = 0.5 * P(i AND j fire) (half joint rate, i != j) +//! +//! # Higher-order correlations +//! +//! K-body rates map each k-subset of detectors to its joint firing +//! probability. For order 1 these are marginals; for order 2, pairwise; +//! for order 3, triple correlations that test whether the DEM's +//! independent error decomposition is adequate. + +use std::collections::BTreeMap; + +/// Flat `n x n` detector flip frequency matrix. +/// +/// Stored row-major. Use `index(i, j, n) = i * n + j`. +pub fn flip_matrix_from_fired(fired_per_shot: &[Vec], num_detectors: usize) -> Vec { + let n = num_detectors; + let shots = fired_per_shot.len(); + if shots == 0 { + return vec![0.0; n * n]; + } + + let inv = 1.0 / shots as f64; + let half_inv = 0.5 * inv; + let mut m = vec![0.0; n * n]; + + for fired in fired_per_shot { + for (ai, &a) in fired.iter().enumerate() { + let a = a as usize; + if a >= n { + continue; + } + m[a * n + a] += inv; + for &b in &fired[ai + 1..] { + let b = b as usize; + if b >= n { + continue; + } + m[a * n + b] += half_inv; + m[b * n + a] += half_inv; + } + } + } + + m +} + +/// Per-round flip frequency matrices. +/// +/// Returns one flat `k x k` matrix per round, where `k = dets_per_round`. +pub fn flip_matrices_by_round( + fired_per_shot: &[Vec], + num_detectors: usize, + dets_per_round: usize, +) -> Vec> { + let k = dets_per_round; + let num_rounds = (num_detectors + k - 1) / k; + let shots = fired_per_shot.len(); + if shots == 0 { + return vec![vec![0.0; k * k]; num_rounds]; + } + + let inv = 1.0 / shots as f64; + let half_inv = 0.5 * inv; + let mut matrices = vec![vec![0.0; k * k]; num_rounds]; + + for fired in fired_per_shot { + // Bin by round + let mut round_local: Vec> = vec![Vec::new(); num_rounds]; + for &d in fired { + let r = d as usize / k; + let local = d as usize % k; + if r < num_rounds { + round_local[r].push(local as u32); + } + } + + for (r, local_ids) in round_local.iter().enumerate() { + let mat = &mut matrices[r]; + for (ai, &a) in local_ids.iter().enumerate() { + let a = a as usize; + mat[a * k + a] += inv; + for &b in &local_ids[ai + 1..] { + let b = b as usize; + mat[a * k + b] += half_inv; + mat[b * k + a] += half_inv; + } + } + } + } + + matrices +} + +/// K-body detector firing rates up to `max_order`. +/// +/// Returns a map from sorted detector index tuples to joint firing +/// probability. Keys are ordered ascending. +pub fn k_body_rates( + fired_per_shot: &[Vec], + num_detectors: usize, + max_order: usize, +) -> BTreeMap, f64> { + let shots = fired_per_shot.len(); + if shots == 0 { + return BTreeMap::new(); + } + + let inv = 1.0 / shots as f64; + let mut rates: BTreeMap, f64> = BTreeMap::new(); + + for fired in fired_per_shot { + let n = fired.len().min(max_order); + for order in 1..=n { + for_each_combination(fired, order, num_detectors as u32, |combo| { + *rates.entry(combo.to_vec()).or_insert(0.0) += inv; + }); + } + } + + rates +} + +/// Per-round k-body rates. Detector indices in the returned maps are +/// round-local (0..dets_per_round-1). +pub fn k_body_rates_by_round( + fired_per_shot: &[Vec], + num_detectors: usize, + dets_per_round: usize, + max_order: usize, +) -> Vec, f64>> { + let k = dets_per_round; + let num_rounds = (num_detectors + k - 1) / k; + let shots = fired_per_shot.len(); + if shots == 0 { + return vec![BTreeMap::new(); num_rounds]; + } + + let inv = 1.0 / shots as f64; + let mut round_rates: Vec, f64>> = vec![BTreeMap::new(); num_rounds]; + + for fired in fired_per_shot { + let mut round_local: Vec> = vec![Vec::new(); num_rounds]; + for &d in fired { + let r = d as usize / k; + let local = d as usize % k; + if r < num_rounds { + round_local[r].push(local as u32); + } + } + + for (r, local_ids) in round_local.iter().enumerate() { + let n = local_ids.len().min(max_order); + let rr = &mut round_rates[r]; + for order in 1..=n { + for_each_combination(local_ids, order, k as u32, |combo| { + *rr.entry(combo.to_vec()).or_insert(0.0) += inv; + }); + } + } + } + + round_rates +} + +/// Compare k-body rates between two sets, grouped by order. +/// +/// Returns a map from order to `(max_rel_error, rms_rel_error, worst_event)`. +pub fn compare_k_body( + sim: &BTreeMap, f64>, + dem: &BTreeMap, f64>, + min_rate: f64, +) -> BTreeMap)> { + let all_keys: BTreeMap<&Vec, ()> = sim.keys().chain(dem.keys()).map(|k| (k, ())).collect(); + + let mut by_order: BTreeMap, f64, f64)>> = BTreeMap::new(); + for (&key, _) in &all_keys { + let s = sim.get(key).copied().unwrap_or(0.0); + let d = dem.get(key).copied().unwrap_or(0.0); + by_order.entry(key.len()).or_default().push((key, s, d)); + } + + let mut result = BTreeMap::new(); + for (order, entries) in &by_order { + let mut max_err = 0.0_f64; + let mut worst: Vec = Vec::new(); + let mut sum_sq = 0.0; + let mut count = 0u64; + + for &(key, s, d) in entries { + if s > min_rate { + let rel = (d / s - 1.0).abs(); + if rel > max_err { + max_err = rel; + worst = key.clone(); + } + sum_sq += rel * rel; + count += 1; + } + } + + let rms = if count > 0 { + (sum_sq / count as f64).sqrt() + } else { + 0.0 + }; + result.insert(*order, (max_err, rms, worst)); + } + + result +} + +/// Compare two flat flip matrices. Returns `(max_rel_err, frob_rel_err, worst_i, worst_j)`. +pub fn compare_flip_matrices( + sim: &[f64], + dem: &[f64], + n: usize, + min_rate: f64, +) -> (f64, f64, usize, usize) { + let mut max_err = 0.0_f64; + let mut worst_i = 0; + let mut worst_j = 0; + let mut sum_sq_diff = 0.0; + let mut sum_sq_sim = 0.0; + + for i in 0..n { + for j in 0..n { + let idx = i * n + j; + let s = sim[idx]; + let d = dem[idx]; + let diff = d - s; + sum_sq_diff += diff * diff; + sum_sq_sim += s * s; + if s > min_rate { + let rel = diff.abs() / s; + if rel > max_err { + max_err = rel; + worst_i = i; + worst_j = j; + } + } + } + } + + let frob = sum_sq_diff.sqrt() / sum_sq_sim.sqrt().max(1e-30); + (max_err, frob, worst_i, worst_j) +} + +// --------------------------------------------------------------------------- +// Hybrid DEM: fit mechanism probabilities to target marginals +// --------------------------------------------------------------------------- + +/// A DEM mechanism: probability + detector/DEM-output sets. +#[derive(Debug, Clone)] +pub struct DemMechanism { + pub probability: f64, + pub detectors: Vec, + pub observables: Vec, +} + +/// Fit DEM mechanism probabilities to match target detector marginals. +/// +/// Given a set of mechanisms (each with a detector set and initial +/// probability) and target per-detector marginal rates, adjusts the +/// mechanism probabilities so the DEM's independent-error marginals +/// match the targets as closely as possible. +/// +/// Uses iterative proportional fitting on the exact DEM marginal equation: +/// +/// p_d = 1/2 - 1/2 * prod_{m: d in S_m} (1 - 2*q_m) +/// +/// Each iteration computes current marginals, then scales each mechanism +/// by the geometric mean of (target/current) ratios for the detectors +/// it affects. Mechanisms with no detector overlap are untouched. +/// +/// Returns the fitted mechanisms and per-detector residual errors. +pub fn fit_dem_to_marginals( + mechanisms: &[DemMechanism], + target_marginals: &[f64], + max_iterations: usize, + tolerance: f64, +) -> (Vec, Vec) { + let num_dets = target_marginals.len(); + let n_mech = mechanisms.len(); + + // Build sparse incidence: for each detector, which mechanisms touch it + let mut det_to_mechs: Vec> = vec![Vec::new(); num_dets]; + for (m, mech) in mechanisms.iter().enumerate() { + for &d in &mech.detectors { + if (d as usize) < num_dets { + det_to_mechs[d as usize].push(m); + } + } + } + + let mut q: Vec = mechanisms.iter().map(|m| m.probability).collect(); + + for _iter in 0..max_iterations { + // Compute current marginals from mechanism probabilities + let mut current = vec![0.0_f64; num_dets]; + for d in 0..num_dets { + let mut prod = 1.0; + for &m in &det_to_mechs[d] { + prod *= 1.0 - 2.0 * q[m]; + } + current[d] = (1.0 - prod) / 2.0; + } + + // Compute per-detector ratios + let mut ratios = vec![1.0_f64; num_dets]; + for d in 0..num_dets { + if current[d] > 1e-20 { + ratios[d] = target_marginals[d] / current[d]; + } else if target_marginals[d] > 1e-20 { + ratios[d] = 10.0; // large but bounded nudge + } + } + + // Scale each mechanism by geometric mean of its detector ratios + let mut max_change = 0.0_f64; + for m in 0..n_mech { + let dets = &mechanisms[m].detectors; + if dets.is_empty() { + continue; + } + let mut log_ratio = 0.0; + let mut count = 0; + for &d in dets { + if (d as usize) < num_dets { + log_ratio += ratios[d as usize].max(1e-10).ln(); + count += 1; + } + } + if count == 0 { + continue; + } + let scale = (log_ratio / count as f64).exp(); + let new_q = (q[m] * scale).clamp(0.0, 0.499); + max_change = max_change.max((new_q - q[m]).abs()); + q[m] = new_q; + } + + if max_change < tolerance { + break; + } + } + + // Compute final residuals + let mut residuals = vec![0.0; num_dets]; + for d in 0..num_dets { + let mut prod = 1.0; + for &m in &det_to_mechs[d] { + prod *= 1.0 - 2.0 * q[m]; + } + let fitted = (1.0 - prod) / 2.0; + residuals[d] = (fitted - target_marginals[d]).abs(); + } + + let fitted: Vec = mechanisms + .iter() + .zip(q.iter()) + .map(|(mech, &prob)| DemMechanism { + probability: prob, + detectors: mech.detectors.clone(), + observables: mech.observables.clone(), + }) + .collect(); + + (fitted, residuals) +} + +/// Format fitted mechanisms as a Stim DEM string. +pub fn mechanisms_to_dem_string(mechanisms: &[DemMechanism]) -> String { + let mut lines = Vec::new(); + for mech in mechanisms { + if mech.probability > 1e-15 { + let mut tokens = Vec::new(); + for &d in &mech.detectors { + tokens.push(format!("D{d}")); + } + for &o in &mech.observables { + tokens.push(format!("L{o}")); + } + if !tokens.is_empty() { + lines.push(format!( + "error({:.10e}) {}", + mech.probability, + tokens.join(" ") + )); + } + } + } + lines.join("\n") +} + +// --- Internal helpers --- + +/// Iterate over all k-combinations of `items` (assumed sorted, < `max_val`), +/// calling `f` with each sorted combination. +fn for_each_combination(items: &[u32], k: usize, _max_val: u32, mut f: impl FnMut(&[u32])) { + if k == 0 || items.len() < k { + return; + } + let mut combo = vec![0u32; k]; + combination_recurse(items, k, 0, 0, &mut combo, &mut f); +} + +fn combination_recurse( + items: &[u32], + k: usize, + start: usize, + depth: usize, + combo: &mut [u32], + f: &mut impl FnMut(&[u32]), +) { + if depth == k { + f(&combo[..k]); + return; + } + let remaining = k - depth; + if start + remaining > items.len() { + return; + } + for i in start..=items.len() - remaining { + combo[depth] = items[i]; + combination_recurse(items, k, i + 1, depth + 1, combo, f); + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_flip_matrix_single_detector() { + // 100 shots, detector 0 fires 30 times + let fired: Vec> = (0..100) + .map(|i| if i < 30 { vec![0] } else { vec![] }) + .collect(); + let m = flip_matrix_from_fired(&fired, 2); + assert!((m[0] - 0.3).abs() < 1e-10); // M[0,0] = 0.3 + assert!(m[1].abs() < 1e-10); // M[0,1] = 0 + assert!(m[3].abs() < 1e-10); // M[1,1] = 0 + } + + #[test] + fn test_flip_matrix_correlated_pair() { + // 100 shots, detectors 0 and 1 always fire together + let fired: Vec> = (0..100) + .map(|i| if i < 20 { vec![0, 1] } else { vec![] }) + .collect(); + let m = flip_matrix_from_fired(&fired, 2); + assert!((m[0] - 0.2).abs() < 1e-10); // M[0,0] + assert!((m[3] - 0.2).abs() < 1e-10); // M[1,1] + assert!((m[1] - 0.1).abs() < 1e-10); // M[0,1] = 0.5 * 0.2 + assert!((m[2] - 0.1).abs() < 1e-10); // M[1,0] = 0.5 * 0.2 + } + + #[test] + fn test_k_body_rates_basic() { + let fired = vec![vec![0, 1, 2], vec![0, 1], vec![0], vec![]]; + let rates = k_body_rates(&fired, 3, 3); + assert!((rates[&vec![0]] - 0.75).abs() < 1e-10); + assert!((rates[&vec![1]] - 0.5).abs() < 1e-10); + assert!((rates[&vec![0, 1]] - 0.5).abs() < 1e-10); + assert!((rates[&vec![0, 1, 2]] - 0.25).abs() < 1e-10); + } + + #[test] + fn test_compare_k_body_basic() { + let mut sim = BTreeMap::new(); + sim.insert(vec![0], 0.1); + sim.insert(vec![1], 0.2); + sim.insert(vec![0, 1], 0.01); + + let mut dem = BTreeMap::new(); + dem.insert(vec![0], 0.1); + dem.insert(vec![1], 0.2); + dem.insert(vec![0, 1], 0.012); + + let result = compare_k_body(&sim, &dem, 0.005); + // 1-body: exact match + assert!(result[&1].0 < 1e-10); + // 2-body: 20% relative error on (0,1) + assert!((result[&2].0 - 0.2).abs() < 1e-10); + } + + #[test] + fn test_by_round_splits_correctly() { + // 4 detectors, 2 per round -> 2 rounds + let fired = vec![vec![0, 2], vec![1, 3]]; + let mats = flip_matrices_by_round(&fired, 4, 2); + assert_eq!(mats.len(), 2); + // Round 0: det 0 in shot 0, det 1 in shot 1 + assert!((mats[0][0] - 0.5).abs() < 1e-10); // M[0,0] + assert!((mats[0][3] - 0.5).abs() < 1e-10); // M[1,1] + // Round 1: det 0(=global 2) in shot 0, det 1(=global 3) in shot 1 + assert!((mats[1][0] - 0.5).abs() < 1e-10); + assert!((mats[1][3] - 0.5).abs() < 1e-10); + } + + #[test] + fn test_fit_dem_to_marginals_exact() { + // Two mechanisms: M0 flips {D0}, M1 flips {D0, D1} + // Target: P(D0) = 0.15, P(D1) = 0.05 + let mechs = vec![ + DemMechanism { + probability: 0.1, + detectors: vec![0], + observables: vec![], + }, + DemMechanism { + probability: 0.05, + detectors: vec![0, 1], + observables: vec![], + }, + ]; + let target = vec![0.15, 0.05]; + let (fitted, residuals) = fit_dem_to_marginals(&mechs, &target, 100, 1e-12); + + // M1 flips only D1, so q1 must satisfy (1-2*q1)/2 ≈ 0.05 → q1 ≈ 0.05 + // Then q0 must satisfy 1/2(1-(1-2*q0)(1-2*q1)) = 0.15 + assert!(residuals[0] < 1e-6, "D0 residual: {}", residuals[0]); + assert!(residuals[1] < 1e-6, "D1 residual: {}", residuals[1]); + assert!(fitted[1].probability > 0.04 && fitted[1].probability < 0.06); + } + + #[test] + fn test_fit_dem_preserves_structure() { + let mechs = vec![ + DemMechanism { + probability: 0.01, + detectors: vec![0], + observables: vec![0], + }, + DemMechanism { + probability: 0.02, + detectors: vec![1], + observables: vec![], + }, + ]; + let target = vec![0.05, 0.08]; + let (fitted, _) = fit_dem_to_marginals(&mechs, &target, 100, 1e-12); + + // Structure preserved + assert_eq!(fitted[0].detectors, vec![0]); + assert_eq!(fitted[0].observables, vec![0]); + assert_eq!(fitted[1].detectors, vec![1]); + } + + #[test] + fn test_mechanisms_to_dem_string() { + let mechs = vec![ + DemMechanism { + probability: 0.01, + detectors: vec![0, 1], + observables: vec![], + }, + DemMechanism { + probability: 0.001, + detectors: vec![2], + observables: vec![0], + }, + ]; + let s = mechanisms_to_dem_string(&mechs); + assert!(s.contains("D0 D1")); + assert!(s.contains("D2 L0")); + } +} diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder.rs index 9ba48eec7..43e640073 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder.rs @@ -19,41 +19,30 @@ //! # Architecture //! //! The DEM builder takes a [`DagFaultInfluenceMap`] (which maps fault locations -//! to their effects on measurements) and detector/observable metadata to produce +//! to their effects on measurements) and detector/DEM-output metadata to produce //! a complete DEM. //! //! # Example //! //! ``` -//! use pecos_qec::fault_tolerance::DagFaultAnalyzer; -//! use pecos_qec::fault_tolerance::dem_builder::DemBuilder; -//! use pecos_quantum::DagCircuit; -//! -//! // Build a simple syndrome extraction circuit -//! let mut dag = DagCircuit::new(); -//! dag.pz(&[2]); -//! dag.cx(&[(0, 2)]); -//! dag.cx(&[(1, 2)]); -//! dag.mz(&[2]); -//! -//! // Build influence map from circuit -//! let analyzer = DagFaultAnalyzer::new(&dag); -//! let influence_map = analyzer.build_influence_map(); -//! -//! // Detector: measurement record -1 (the single measurement) -//! let detectors_json = r#"[{"id": 0, "records": [-1]}]"#; -//! let observables_json = "[]"; -//! -//! // Build DEM with noise model +//! use pecos_qec::DemBuilder; +//! use pecos_qec::fault_tolerance::propagator::DagFaultInfluenceMap; +//! +//! # fn main() -> Result<(), Box> { +//! // Normally `influence_map` comes from `DagFaultAnalyzer::build_influence_map()`; +//! // here we use an empty map to keep the doctest self-contained. +//! let influence_map = DagFaultInfluenceMap::with_capacity(0); +//! //! let dem = DemBuilder::new(&influence_map) //! .with_noise(0.01, 0.01, 0.01, 0.01) -//! .with_detectors_json(detectors_json).unwrap() -//! .with_observables_json(observables_json).unwrap() +//! .with_detectors_json("[]")? +//! .with_observables_json("[]")? //! .build(); //! -//! // Output in Stim-compatible format -//! let dem_str = dem.to_string(); -//! assert!(!dem_str.is_empty()); +//! // Output in Stim format (non-decomposed). +//! let _ = dem.to_string(); +//! # Ok(()) +//! # } //! ``` //! //! # Error Decomposition @@ -75,64 +64,40 @@ //! Pauli combinations (IX, IY, IZ, XI, ..., ZZ) are considered. //! //! - **XOR effect combining**: Correlated errors are properly combined -//! by XOR-ing detector/observable effects. +//! by XOR-ing detector/DEM-output effects. //! -//! - **Independent probability combination**: When the same error mechanism +//! - **Independent probability combination**: When the same fault mechanism //! is triggered by multiple error sources, probabilities are combined //! using p1*(1-p2) + p2*(1-p1). //! //! # Measurement Noise Model (MNM) //! -//! In addition to the DEM, this module provides a Measurement Noise Model (MNM) -//! for fast approximate sampling. Unlike the DEM which maps to detectors, the -//! MNM maps directly to raw measurement effects. -//! -//! ``` -//! use pecos_qec::fault_tolerance::DagFaultAnalyzer; -//! use pecos_qec::fault_tolerance::dem_builder::MemBuilder; -//! use pecos_quantum::DagCircuit; -//! use rand::SeedableRng; -//! use rand::rngs::SmallRng; -//! -//! let mut dag = DagCircuit::new(); -//! dag.pz(&[2]); -//! dag.cx(&[(0, 2)]); -//! dag.cx(&[(1, 2)]); -//! dag.mz(&[2]); -//! -//! let analyzer = DagFaultAnalyzer::new(&dag); -//! let influence_map = analyzer.build_influence_map(); -//! -//! // Build MNM for fast sampling -//! let mnm = MemBuilder::new(&influence_map) -//! .with_noise(0.01, 0.01, 0.01, 0.01) -//! .build(); -//! -//! // Sample measurement outcomes -//! let mut rng = SmallRng::seed_from_u64(42); -//! let outcomes = mnm.sample(&mut rng); -//! ``` -//! -//! The MNM aggregates fault locations by their measurement effects (which -//! measurements flip together), enabling faster sampling with fewer random -//! draws compared to per-fault-location sampling. +//! The [`DemSampler`] provides both raw measurement and detector-event +//! output from a single mechanism engine. It replaces the former `MemBuilder` +//! (measurement-level) and `DemSamplerBuilder` (detector-level) paths with a +//! unified interface that validates detector definitions at build time. mod builder; mod dem_sampler; mod equivalence; -mod mem_builder; +pub(crate) mod sampler; mod types; pub use builder::{DemBuilder, DemBuilderError}; -pub use dem_sampler::{DemSampler, DemSamplerBuilder, SamplingStatistics}; +pub use dem_sampler::{SamplingEngine, SamplingStatistics}; pub use equivalence::{ ComparisonDetails, ComparisonMethod, DemParseError, EffectKey, EquivalenceResult, MechanismComponent, ParsedDem, ParsedMechanism, ProbabilityMismatch, compare_dems_exact, compare_dems_statistical, verify_dem_equivalence, }; -pub use mem_builder::MemBuilder; +pub use sampler::{ + DemSampler, DemSamplerBuilder, DetectorValidationError, DualSampleResult, OutputMode, + SamplerLabels, +}; pub use types::{ - DecomposedError, DetectorDef, DetectorErrorModel, ErrorContribution, ErrorMechanism, - ErrorSourceType, LogicalObservable, MeasurementMechanism, MeasurementNoiseModel, NoiseConfig, - combine_probabilities, + ContributionEffectSummary, ContributionRenderRecord, ContributionRenderStrategy, + ContributionRenderSummary, DecomposedFault, DemOutput, DetectorDef, DetectorErrorModel, + DirectSourceFamily, FaultContribution, FaultMechanism, FaultSourceType, NoiseConfig, + PauliProbs, PauliWeights, PecosDemMetadataError, TwoDetectorDirectRenderPolicy, + combine_probabilities, record_offset_to_absolute_index, }; diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs index b02ccb6d3..62a167057 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs @@ -13,10 +13,11 @@ //! DEM (Detector Error Model) builder implementation. //! //! This module provides the main builder for constructing DEMs from fault -//! influence maps and detector/observable metadata. +//! influence maps and detector/DEM-output metadata. use super::types::{ - DetectorDef, DetectorErrorModel, ErrorMechanism, LogicalObservable, NoiseConfig, + DemOutput, DetectorDef, DetectorErrorModel, DirectSourceComponents, FaultMechanism, + NoiseConfig, SourceMetadata, record_offset_to_absolute_index, }; use crate::fault_tolerance::propagator::{DagFaultInfluenceMap, Pauli}; use pecos_core::gate_type::GateType; @@ -48,38 +49,38 @@ struct ParsedObservable { /// Builder for Detector Error Models (DEMs). /// -/// Constructs a DEM from a fault influence map and detector/observable metadata. -/// Uses the per-qubit fault model for accurate depolarizing noise analysis. +/// # Simple API (recommended) /// -/// # Example +/// For most use cases, use the one-liner: /// -/// ``` -/// use pecos_qec::fault_tolerance::DagFaultAnalyzer; +/// ```ignore /// use pecos_qec::fault_tolerance::dem_builder::DemBuilder; -/// use pecos_quantum::DagCircuit; /// -/// let mut dag = DagCircuit::new(); -/// dag.pz(&[2]); -/// dag.cx(&[(0, 2)]); -/// dag.cx(&[(1, 2)]); -/// dag.mz(&[2]); +/// // Build DEM from circuit + noise (reads detectors from circuit metadata) +/// let dem = DemBuilder::from_circuit(&dag, 0.001, 0.01, 0.001, 0.001); +/// println!("{}", dem.to_string()); +/// ``` +/// +/// Also works with `TickCircuit`: /// -/// let analyzer = DagFaultAnalyzer::new(&dag); -/// let influence_map = analyzer.build_influence_map(); -/// let detectors_json = r#"[{"id": 0, "records": [-1]}]"#; -/// let observables_json = "[]"; +/// ```ignore +/// # use pecos_qec::fault_tolerance::dem_builder::DemBuilder; +/// let dem = DemBuilder::from_tick_circuit(&tc, 0.001, 0.01, 0.001, 0.001); +/// ``` +/// +/// # Advanced API /// +/// For custom influence maps, non-standard noise, or manual detector +/// definitions, use the step-by-step builder: +/// +/// ```no_run +/// # use pecos_qec::fault_tolerance::dem_builder::DemBuilder; +/// # use pecos_qec::fault_tolerance::propagator::DagFaultInfluenceMap; +/// # let influence_map = DagFaultInfluenceMap::with_capacity(0); /// let dem = DemBuilder::new(&influence_map) /// .with_noise(0.01, 0.01, 0.01, 0.01) -/// .with_detectors_json(detectors_json).unwrap() -/// .with_observables_json(observables_json).unwrap() +/// .with_detectors_json("[]").unwrap() /// .build(); -/// -/// // Non-decomposed output (matches Stim's decompose_errors=False) -/// println!("{}", dem.to_string()); -/// -/// // Decomposed output (matches Stim's decompose_errors=True) -/// println!("{}", dem.to_string_decomposed()); /// ``` pub struct DemBuilder<'a> { /// Reference to the fault influence map. @@ -98,6 +99,44 @@ pub struct DemBuilder<'a> { } impl<'a> DemBuilder<'a> { + /// Build a `DetectorErrorModel` directly from a circuit and noise. + /// + /// One-liner for the common case. Reads detector/DEM output definitions + /// from circuit metadata (`"detectors"`, `"observables"` attributes). + /// + /// ```ignore + /// use pecos_qec::fault_tolerance::dem_builder::DemBuilder; + /// let dem = DemBuilder::from_circuit(&dag, 0.001, 0.01, 0.001, 0.001); + /// println!("{}", dem.to_string()); + /// ``` + /// Build a `DetectorErrorModel` directly from a `DagCircuit` and noise. + /// + /// One-liner for the common case. Reads detector/DEM output definitions + /// from circuit metadata. + pub fn from_circuit( + circuit: &pecos_quantum::DagCircuit, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + ) -> DetectorErrorModel { + build_dem_from_circuit(circuit, p1, p2, p_meas, p_prep) + } + + /// Build a `DetectorErrorModel` from a `TickCircuit` and noise. + /// + /// Converts to `DagCircuit` internally. + pub fn from_tick_circuit( + circuit: &pecos_quantum::TickCircuit, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + ) -> DetectorErrorModel { + let dag = pecos_quantum::DagCircuit::from(circuit); + build_dem_from_circuit(&dag, p1, p2, p_meas, p_prep) + } + /// Creates a new DEM builder from a fault influence map. #[must_use] pub fn new(influence_map: &'a DagFaultInfluenceMap) -> Self { @@ -111,10 +150,17 @@ impl<'a> DemBuilder<'a> { } } - /// Sets the noise configuration. + /// Sets the noise configuration from individual parameters. + #[must_use] + pub fn with_noise(mut self, p1: f64, p2: f64, p_meas: f64, p_prep: f64) -> Self { + self.noise = NoiseConfig::new(p1, p2, p_meas, p_prep); + self + } + + /// Sets the full noise configuration (supports custom weights, T1/T2, idle). #[must_use] - pub fn with_noise(mut self, p1: f64, p2: f64, p_meas: f64, p_init: f64) -> Self { - self.noise = NoiseConfig::new(p1, p2, p_meas, p_init); + pub fn with_noise_config(mut self, noise: NoiseConfig) -> Self { + self.noise = noise; self } @@ -133,6 +179,13 @@ impl<'a> DemBuilder<'a> { /// indices (which may use a different order based on DAG topology). /// /// # Arguments + /// Set the measurement order for legacy circuits without `MeasId` on gates. + /// + /// **Not needed for circuits built with `TickCircuit.mz()`** — the `MeasId` + /// values on gates ensure correct ordering automatically. + /// + /// Only use this for circuits where MZ gates lack `meas_ids` (e.g., + /// circuits imported from external formats without measurement IDs). /// /// * `order` - List of qubit indices in measurement execution order. /// `order[i]` is the qubit measured at `TickCircuit` measurement index `i`. @@ -144,11 +197,13 @@ impl<'a> DemBuilder<'a> { /// Parses and sets detector definitions from JSON. /// + /// Each object accepts either `"id"` or `"detector_id"` as the identifier key. + /// /// Expected format: /// ```json /// [ /// {"id": 0, "coords": [0.0, 0.0, 0.0], "records": [-1, -5]}, - /// {"id": 1, "coords": [1.0, 0.0, 0.0], "records": [-2]} + /// {"detector_id": 1, "coords": [1.0, 0.0, 0.0], "records": [-2]} /// ] /// ``` /// @@ -162,12 +217,10 @@ impl<'a> DemBuilder<'a> { /// Parses and sets observable definitions from JSON. /// - /// Expected format: - /// ```json - /// [ - /// {"id": 0, "records": [-1, -3, -5]} - /// ] - /// ``` + /// Tracked operators are carried by the influence map; this helper is only + /// for observable metadata. + /// + /// Each object accepts either `"id"` or `"observable_id"` as the identifier key. /// /// # Errors /// @@ -177,6 +230,21 @@ impl<'a> DemBuilder<'a> { Ok(self) } + /// Sets observable definitions from measurement-record offsets. + #[must_use] + pub fn with_observable_records(mut self, records: Vec>) -> Self { + self.observables = records + .into_iter() + .enumerate() + .map(|(id, records)| ParsedObservable { + #[allow(clippy::cast_possible_truncation)] // observable count fits in u32 + id: id as u32, + records, + }) + .collect(); + self + } + /// Builds the Detector Error Model with source tracking. /// /// This performs fault propagation analysis and tracks error sources (X/Z vs Y) @@ -185,8 +253,10 @@ impl<'a> DemBuilder<'a> { /// Use `dem.to_string()` or `dem.to_string_decomposed()` for output. #[must_use] pub fn build(&self) -> DetectorErrorModel { - let mut dem = - DetectorErrorModel::with_capacity(self.detectors.len(), self.observables.len()); + let num_influence_dem_outputs = self + .num_influence_dem_outputs() + .max(self.influence_map.dem_output_metadata.len()); + let mut dem = DetectorErrorModel::with_capacity(self.detectors.len(), self.observables.len()); // Add detector definitions for det in &self.detectors { @@ -198,13 +268,42 @@ impl<'a> DemBuilder<'a> { dem.add_detector(def); } - // Add observable definitions + // Add non-detector outputs carried directly by the influence map. + // Metadata-bearing outputs use separate compact ID spaces for standard + // observables and PECOS tracked operators. + if self.influence_map.dem_output_metadata.is_empty() { + for dem_output_idx in 0..num_influence_dem_outputs { + #[allow(clippy::cast_possible_truncation)] // DEM output count fits in u32 + dem.add_observable(DemOutput::new(dem_output_idx as u32)); + } + } else { + for (internal_idx, metadata) in + self.influence_map.dem_output_metadata.iter().enumerate() + { + #[allow(clippy::cast_possible_truncation)] // DEM output count fits in u32 + let internal_id = internal_idx as u32; + if let Some(dem_output_id) = self + .influence_map + .tracked_op_id_for_internal_dem_output(internal_id) + { + dem.add_tracked_operator(DemOutput::from_metadata(dem_output_id, metadata)); + } else if let Some(dem_output_id) = self + .influence_map + .observable_id_for_internal_dem_output(internal_id) + { + dem.add_observable(DemOutput::from_metadata(dem_output_id, metadata)); + } + } + } + + // Add observable definitions in the standard Stim `L` namespace. + // Observable IDs are not shifted by tracked operators. for obs in &self.observables { - let def = LogicalObservable::new(obs.id).with_records(obs.records.iter().copied()); + let def = DemOutput::new(obs.id).with_records(obs.records.iter().copied()); dem.add_observable(def); } - // Build measurement -> detector/observable mappings + // Build measurement -> detector/DEM-output mappings let (meas_to_detectors, meas_to_observables) = self.build_measurement_mappings(); // Process all fault locations with source tracking @@ -217,6 +316,13 @@ impl<'a> DemBuilder<'a> { dem } + fn num_influence_dem_outputs(&self) -> usize { + self.influence_map + .influences + .max_dem_output_index() + .map_or(0, |idx| idx + 1) + } + /// Processes fault locations with source tracking. /// /// This version uses `add_direct_contribution` and `add_y_decomposed_contribution` @@ -234,32 +340,42 @@ impl<'a> DemBuilder<'a> { for (loc_idx, loc) in locations.iter().enumerate() { match loc.gate_type { - GateType::PZ | GateType::QAlloc => { - if self.noise.p_init > 0.0 && !loc.before { - self.process_prep_fault_source_tracked( - loc_idx, - dem, - meas_to_detectors, - meas_to_observables, - ); - } + GateType::PZ | GateType::QAlloc if self.noise.p_prep > 0.0 && !loc.before => { + self.process_prep_fault_source_tracked( + loc_idx, + dem, + meas_to_detectors, + meas_to_observables, + ); } - GateType::MZ | GateType::MeasureFree => { - if self.noise.p_meas > 0.0 && loc.before { - self.process_meas_fault_source_tracked( - loc_idx, - dem, - meas_to_detectors, - meas_to_observables, - ); - } + GateType::MZ | GateType::MeasureFree if self.noise.p_meas > 0.0 && loc.before => { + self.process_meas_fault_source_tracked( + loc_idx, + dem, + meas_to_detectors, + meas_to_observables, + ); } - GateType::CX | GateType::CZ => { - if !loc.before { - cx_groups.entry(loc.node).or_default().push(loc_idx); - } + GateType::CX + | GateType::CZ + | GateType::CY + | GateType::SZZ + | GateType::SZZdg + | GateType::SXX + | GateType::SXXdg + | GateType::SYY + | GateType::SYYdg + | GateType::SWAP + | GateType::RXX + | GateType::RYY + | GateType::RZZ + if !loc.before => + { + cx_groups.entry(loc.node).or_default().push(loc_idx); } GateType::H + | GateType::F + | GateType::Fdg | GateType::SZ | GateType::SZdg | GateType::SX @@ -268,10 +384,32 @@ impl<'a> DemBuilder<'a> { | GateType::SYdg | GateType::X | GateType::Y - | GateType::Z => { - if self.noise.p1 > 0.0 && !loc.before { - self.process_single_qubit_fault_source_tracked( + | GateType::Z + | GateType::T + | GateType::Tdg + | GateType::RX + | GateType::RY + | GateType::RZ + | GateType::U + | GateType::R1XY + if self.noise.p1 > 0.0 && !loc.before => + { + self.process_single_qubit_fault_source_tracked( + loc_idx, + dem, + meas_to_detectors, + meas_to_observables, + ); + } + GateType::Idle if !loc.before => { + // Duration values are small integers; precision loss is not a concern. + #[allow(clippy::cast_precision_loss)] + let duration = loc.idle_duration.max(1) as f64; + let pauli_probs = self.noise.idle_pauli_probs(duration); + if pauli_probs.total() > 0.0 { + self.process_idle_fault_source_tracked( loc_idx, + &pauli_probs, dem, meas_to_detectors, meas_to_observables, @@ -282,19 +420,43 @@ impl<'a> DemBuilder<'a> { } } - // Process two-qubit gates + // Process two-qubit gates in parallel. + // Collect all CX pairs, process with rayon, merge results. if self.noise.p2 > 0.0 { + use rayon::prelude::*; + + let mut all_pairs: Vec<(usize, usize)> = Vec::new(); for (_, loc_indices) in cx_groups { - if loc_indices.len() == 2 { - self.process_two_qubit_fault_source_tracked( - loc_indices[0], - loc_indices[1], - dem, - meas_to_detectors, - meas_to_observables, - ); + for pair in loc_indices.chunks(2) { + if pair.len() == 2 { + all_pairs.push((pair[0], pair[1])); + } } } + + let chunk_size = all_pairs.len().div_ceil(rayon::current_num_threads()); + + let thread_results: Vec = all_pairs + .par_chunks(chunk_size.max(1)) + .map(|chunk| { + let mut local_dem = DetectorErrorModel::with_capacity(0, 0); + for &(loc1, loc2) in chunk { + self.process_two_qubit_fault_source_tracked( + loc1, + loc2, + &mut local_dem, + meas_to_detectors, + meas_to_observables, + ); + } + local_dem + }) + .collect(); + + // Merge contributions from all threads + for local_dem in thread_results { + dem.merge_contributions_from(local_dem); + } } } @@ -310,7 +472,16 @@ impl<'a> DemBuilder<'a> { let mechanism = self.compute_mechanism(loc_idx, Pauli::X, meas_to_detectors, meas_to_observables); if !mechanism.is_empty() { - dem.add_direct_contribution(mechanism, self.noise.p_init); + dem.add_direct_contribution_with_source( + mechanism, + self.noise.p_prep, + SourceMetadata::new( + &[loc_idx], + &[Pauli::X], + &[self.influence_map.locations[loc_idx].gate_type], + &[self.influence_map.locations[loc_idx].before], + ), + ); } } @@ -326,7 +497,16 @@ impl<'a> DemBuilder<'a> { let mechanism = self.compute_mechanism(loc_idx, Pauli::X, meas_to_detectors, meas_to_observables); if !mechanism.is_empty() { - dem.add_direct_contribution(mechanism, self.noise.p_meas); + dem.add_direct_contribution_with_source( + mechanism, + self.noise.p_meas, + SourceMetadata::new( + &[loc_idx], + &[Pauli::X], + &[self.influence_map.locations[loc_idx].gate_type], + &[self.influence_map.locations[loc_idx].before], + ), + ); } } @@ -338,7 +518,18 @@ impl<'a> DemBuilder<'a> { meas_to_detectors: &BTreeMap>, meas_to_observables: &BTreeMap>, ) { - let prob = per_channel_probability(self.noise.p1, 3); + // Per-Pauli probabilities: custom weights or uniform p/3 + let (px, py, pz) = if let Some(ref weights) = self.noise.p1_weights { + use pecos_core::pauli::constructors::{X, Y, Z}; + ( + self.noise.p1 * weights.weight_for(&X(0)), + self.noise.p1 * weights.weight_for(&Y(0)), + self.noise.p1 * weights.weight_for(&Z(0)), + ) + } else { + let p = per_channel_probability(self.noise.p1, 3); + (p, p, p) + }; let x_effect = self.compute_mechanism(loc_idx, Pauli::X, meas_to_detectors, meas_to_observables); @@ -347,28 +538,128 @@ impl<'a> DemBuilder<'a> { // X error: direct source if !x_effect.is_empty() { - dem.add_direct_contribution(x_effect.clone(), prob); + dem.add_direct_contribution_with_source( + x_effect.clone(), + px, + SourceMetadata::new( + &[loc_idx], + &[Pauli::X], + &[self.influence_map.locations[loc_idx].gate_type], + &[self.influence_map.locations[loc_idx].before], + ), + ); } // Z error: direct source if !z_effect.is_empty() { - dem.add_direct_contribution(z_effect.clone(), prob); + dem.add_direct_contribution_with_source( + z_effect.clone(), + pz, + SourceMetadata::new( + &[loc_idx], + &[Pauli::Z], + &[self.influence_map.locations[loc_idx].gate_type], + &[self.influence_map.locations[loc_idx].before], + ), + ); } // Y error: Y = XZ, so effect is XOR of X and Z effects - // Handle all cases: - // 1. Both non-empty and different: decomposable Y = X ^ Z - // 2. X non-empty, Z empty: Y has same effect as X (direct) - // 3. X empty, Z non-empty: Y has same effect as Z (direct) - // 4. Both non-empty and equal: Y effect is empty (X XOR X = nothing) let y_effect = x_effect.xor(&z_effect); if !y_effect.is_empty() { if !x_effect.is_empty() && !z_effect.is_empty() { - // Both non-empty, so Y is decomposable as X ^ Z - dem.add_y_decomposed_contribution(&x_effect, &z_effect, prob); + dem.add_y_decomposed_contribution_with_source( + &x_effect, + &z_effect, + py, + SourceMetadata::new( + &[loc_idx], + &[Pauli::Y], + &[self.influence_map.locations[loc_idx].gate_type], + &[self.influence_map.locations[loc_idx].before], + ), + ); } else { // One is empty, so Y has same effect as the non-empty one (direct source) - dem.add_direct_contribution(y_effect, prob); + dem.add_direct_contribution_with_source( + y_effect, + py, + SourceMetadata::new( + &[loc_idx], + &[Pauli::Y], + &[self.influence_map.locations[loc_idx].gate_type], + &[self.influence_map.locations[loc_idx].before], + ), + ); + } + } + } + + /// Processes an idle gate fault with per-Pauli probabilities. + fn process_idle_fault_source_tracked( + &self, + loc_idx: usize, + pauli_probs: &super::PauliProbs, + dem: &mut DetectorErrorModel, + meas_to_detectors: &BTreeMap>, + meas_to_observables: &BTreeMap>, + ) { + let x_effect = + self.compute_mechanism(loc_idx, Pauli::X, meas_to_detectors, meas_to_observables); + let z_effect = + self.compute_mechanism(loc_idx, Pauli::Z, meas_to_detectors, meas_to_observables); + + if !x_effect.is_empty() { + dem.add_direct_contribution_with_source( + x_effect.clone(), + pauli_probs.px, + SourceMetadata::new( + &[loc_idx], + &[Pauli::X], + &[self.influence_map.locations[loc_idx].gate_type], + &[self.influence_map.locations[loc_idx].before], + ), + ); + } + + if !z_effect.is_empty() { + dem.add_direct_contribution_with_source( + z_effect.clone(), + pauli_probs.pz, + SourceMetadata::new( + &[loc_idx], + &[Pauli::Z], + &[self.influence_map.locations[loc_idx].gate_type], + &[self.influence_map.locations[loc_idx].before], + ), + ); + } + + let y_effect = x_effect.xor(&z_effect); + if !y_effect.is_empty() { + if !x_effect.is_empty() && !z_effect.is_empty() { + dem.add_y_decomposed_contribution_with_source( + &x_effect, + &z_effect, + pauli_probs.py, + SourceMetadata::new( + &[loc_idx], + &[Pauli::Y], + &[self.influence_map.locations[loc_idx].gate_type], + &[self.influence_map.locations[loc_idx].before], + ), + ); + } else { + dem.add_direct_contribution_with_source( + y_effect, + pauli_probs.py, + SourceMetadata::new( + &[loc_idx], + &[Pauli::Y], + &[self.influence_map.locations[loc_idx].gate_type], + &[self.influence_map.locations[loc_idx].before], + ), + ); } } } @@ -382,7 +673,9 @@ impl<'a> DemBuilder<'a> { meas_to_detectors: &BTreeMap>, meas_to_observables: &BTreeMap>, ) { - let prob = per_channel_probability(self.noise.p2, 15); + let uniform_prob = per_channel_probability(self.noise.p2, 15); + let loc1_meta = &self.influence_map.locations[loc1]; + let loc2_meta = &self.influence_map.locations[loc2]; // Compute base effects for X and Z on each qubit let x1 = self.compute_mechanism(loc1, Pauli::X, meas_to_detectors, meas_to_observables); @@ -391,9 +684,9 @@ impl<'a> DemBuilder<'a> { let z2 = self.compute_mechanism(loc2, Pauli::Z, meas_to_detectors, meas_to_observables); // Build effect table for all 16 Pauli combinations - let get_single_effect = |p: u8, x: &ErrorMechanism, z: &ErrorMechanism| -> ErrorMechanism { + let get_single_effect = |p: u8, x: &FaultMechanism, z: &FaultMechanism| -> FaultMechanism { match p { - 0 => ErrorMechanism::new(), // I + 0 => FaultMechanism::new(), // I 1 => x.clone(), // X 2 => x.xor(z), // Y = X XOR Z 3 => z.clone(), // Z @@ -401,7 +694,7 @@ impl<'a> DemBuilder<'a> { } }; - let mut effects: [[ErrorMechanism; 4]; 4] = Default::default(); + let mut effects: [[FaultMechanism; 4]; 4] = Default::default(); for p1 in 0..4u8 { for p2 in 0..4u8 { let e1 = get_single_effect(p1, &x1, &z1); @@ -410,6 +703,17 @@ impl<'a> DemBuilder<'a> { } } + // Helper to build PauliString from (p1, p2) indices for weight lookup + let pauli_from_index = |idx: u8| -> pecos_core::Pauli { + match idx { + 0 => pecos_core::Pauli::I, + 1 => pecos_core::Pauli::X, + 2 => pecos_core::Pauli::Y, + 3 => pecos_core::Pauli::Z, + _ => unreachable!(), + } + }; + // Process all 15 non-trivial Pauli combinations for p1 in 0u8..4 { for p2 in 0u8..4 { @@ -422,21 +726,41 @@ impl<'a> DemBuilder<'a> { continue; } + // Per-event probability: custom weights or uniform + let prob = if let Some(ref weights) = self.noise.p2_weights { + let mut paulis = Vec::new(); + let pa1 = pauli_from_index(p1); + let pa2 = pauli_from_index(p2); + if pa1 != pecos_core::Pauli::I { + paulis.push((pa1, pecos_core::QubitId::from(0usize))); + } + if pa2 != pecos_core::Pauli::I { + paulis.push((pa2, pecos_core::QubitId::from(1usize))); + } + let ps = pecos_core::PauliString::with_phase_and_paulis( + pecos_core::QuarterPhase::PlusOne, + paulis, + ); + self.noise.p2 * weights.weight_for(&ps) + } else { + uniform_prob + }; + // Get component effects (P1I and IP2) let e1 = &effects[p1 as usize][0]; // P1 on qubit 1, I on qubit 2 let e2 = &effects[0][p2 as usize]; // I on qubit 1, P2 on qubit 2 // Check if this is a "graphlike decomposable" source: - // - Combined effect has exactly 2 detectors and no logicals + // - Combined effect has exactly 2 detectors and no dem_outputs // - Both component effects are non-empty // - Both component effects are graphlike (≤2 detectors) - if effect.num_detectors() == 2 - && effect.logicals.is_empty() + let graphlike_decomposable = effect.num_detectors() == 2 + && effect.dem_outputs.is_empty() && !e1.is_empty() && !e2.is_empty() && e1.num_detectors() <= 2 - && e2.num_detectors() <= 2 - { + && e2.num_detectors() <= 2; + if graphlike_decomposable { dem.mark_graphlike_decomposable(effect.detectors[0], effect.detectors[1]); } @@ -450,17 +774,37 @@ impl<'a> DemBuilder<'a> { // Only truly decomposable if both components are non-empty and different. // add_y_decomposed_contribution handles routing to Direct when appropriate. - dem.add_y_decomposed_contribution(e_a, e_b, prob); + dem.add_y_decomposed_contribution_with_source( + e_a, + e_b, + prob, + SourceMetadata::new( + &[loc1, loc2], + &[Pauli::from_u8(p1), Pauli::from_u8(p2)], + &[loc1_meta.gate_type, loc2_meta.gate_type], + &[loc1_meta.before, loc2_meta.before], + ), + ); } else { // Non-Y channel (XI, IX, ZI, IZ, XX, XZ, ZX, ZZ) // These are always direct sources. - dem.add_direct_contribution(effect.clone(), prob); + dem.add_direct_contribution_with_source_components( + effect.clone(), + prob, + SourceMetadata::new( + &[loc1, loc2], + &[Pauli::from_u8(p1), Pauli::from_u8(p2)], + &[loc1_meta.gate_type, loc2_meta.gate_type], + &[loc1_meta.before, loc2_meta.before], + ), + DirectSourceComponents::new(e1, e2), + ); } } } } - /// Builds mappings from measurement indices to detector/observable IDs. + /// Builds mappings from measurement indices to detector/DEM-output IDs. /// /// When `measurement_order` is provided, this properly maps between /// `TickCircuit` measurement indices (used in record offsets) and influence @@ -522,14 +866,10 @@ impl<'a> DemBuilder<'a> { for det in &self.detectors { for &rec in &det.records { - // Convert negative record offset to absolute measurement index in TickCircuit order - #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] // measurement count fits in i32 - #[allow(clippy::cast_sign_loss)] - // negative offset + total count yields valid index - let tc_meas_idx = (self.num_measurements as i32 + rec) as usize; - - // Map to influence map index - if let Some(&influence_idx) = tc_to_influence.get(&tc_meas_idx) { + if let Some(tc_meas_idx) = + record_offset_to_absolute_index(self.num_measurements, rec) + && let Some(&influence_idx) = tc_to_influence.get(&tc_meas_idx) + { meas_to_detectors .entry(influence_idx) .or_default() @@ -540,12 +880,10 @@ impl<'a> DemBuilder<'a> { for obs in &self.observables { for &rec in &obs.records { - #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] // measurement count fits in i32 - #[allow(clippy::cast_sign_loss)] - // negative offset + total count yields valid index - let tc_meas_idx = (self.num_measurements as i32 + rec) as usize; - - if let Some(&influence_idx) = tc_to_influence.get(&tc_meas_idx) { + if let Some(tc_meas_idx) = + record_offset_to_absolute_index(self.num_measurements, rec) + && let Some(&influence_idx) = tc_to_influence.get(&tc_meas_idx) + { meas_to_observables .entry(influence_idx) .or_default() @@ -557,15 +895,15 @@ impl<'a> DemBuilder<'a> { (meas_to_detectors, meas_to_observables) } - /// Computes the error mechanism for a fault at the given location and Pauli type. + /// Computes the fault mechanism for a fault at the given location and Pauli type. fn compute_mechanism( &self, loc_idx: usize, pauli: Pauli, meas_to_detectors: &BTreeMap>, meas_to_observables: &BTreeMap>, - ) -> ErrorMechanism { - // Get the Rust detector indices that this fault flips + ) -> FaultMechanism { + // Get the measurement indices that this fault flips let rust_dets = self .influence_map .get_detector_indices(loc_idx, pauli.as_u8()); @@ -574,6 +912,13 @@ impl<'a> DemBuilder<'a> { let mut triggered_dets: SmallVec<[u32; 4]> = SmallVec::new(); let mut triggered_obs: SmallVec<[u32; 2]> = SmallVec::new(); + for dem_output_idx in self + .influence_map + .get_observable_indices(loc_idx, pauli.as_u8()) + { + xor_toggle_2(&mut triggered_obs, dem_output_idx); + } + for &rust_det in rust_dets { let meas_idx = rust_det as usize; @@ -596,7 +941,7 @@ impl<'a> DemBuilder<'a> { triggered_dets.sort_unstable(); triggered_obs.sort_unstable(); - ErrorMechanism::from_sorted(triggered_dets, triggered_obs) + FaultMechanism::from_sorted(triggered_dets, triggered_obs) } } @@ -737,11 +1082,12 @@ fn parse_detectors_json(json: &str) -> Result, DemBuilderErr /// Parses a single detector object. fn parse_single_detector(json: &str) -> Result { - #[allow(clippy::cast_sign_loss, clippy::cast_possible_truncation)] - // detector IDs are small non-negative integers - let id = extract_number(json, "\"id\"") - .ok_or_else(|| DemBuilderError::ParseError("missing detector id".into()))? - as u32; + let id = extract_u32( + json, + &["\"id\"", "\"detector_id\""], + "missing detector id", + "detector id out of range", + )?; let coords = extract_coords(json); let records = extract_records(json); @@ -794,11 +1140,12 @@ fn parse_observables_json(json: &str) -> Result, DemBuilde /// Parses a single observable object. fn parse_single_observable(json: &str) -> Result { - #[allow(clippy::cast_sign_loss, clippy::cast_possible_truncation)] - // observable IDs are small non-negative integers - let id = extract_number(json, "\"id\"") - .ok_or_else(|| DemBuilderError::ParseError("missing observable id".into()))? - as u32; + let id = extract_u32( + json, + &["\"id\"", "\"observable_id\""], + "missing observable id", + "observable id out of range", + )?; let records = extract_records(json); @@ -816,6 +1163,19 @@ fn extract_number(json: &str, key: &str) -> Option { num_str.parse().ok() } +fn extract_u32( + json: &str, + keys: &[&str], + missing_message: &str, + range_message: &str, +) -> Result { + let value = keys + .iter() + .find_map(|key| extract_number(json, key)) + .ok_or_else(|| DemBuilderError::ParseError(missing_message.into()))?; + u32::try_from(value).map_err(|_| DemBuilderError::ParseError(range_message.into())) +} + /// Extracts coordinates array [x, y, t]. fn extract_coords(json: &str) -> Option<[f64; 3]> { let pos = json.find("\"coords\"")?; @@ -853,6 +1213,121 @@ fn extract_records(json: &str) -> Vec { Vec::new() } +// ============================================================================ +// Convenience: build DEM from circuit (free function to handle lifetimes) +// ============================================================================ + +/// Build a `DetectorErrorModel` from a `DagCircuit` and noise parameters. +/// +/// Reads detector/DEM output definitions from circuit metadata attributes. +fn build_dem_from_circuit( + circuit: &pecos_quantum::DagCircuit, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, +) -> DetectorErrorModel { + use crate::fault_tolerance::influence_builder::InfluenceBuilder; + use crate::fault_tolerance::propagator::DagFaultAnalyzer; + use pecos_num::graph::Attribute; + + let mut influence_map = DagFaultAnalyzer::new(circuit).build_influence_map(); + let annotated_observable_records = + observable_records_from_annotations(circuit, &influence_map); + let annotation_map = InfluenceBuilder::new(circuit) + .with_circuit_annotations(circuit) + .build(); + influence_map.merge_dem_outputs_from(&annotation_map); + + // Extract metadata before building (to avoid borrow issues) + let det_json = circuit.get_attr("detectors").and_then(|a| { + if let Attribute::String(s) = a { + Some(s.clone()) + } else { + None + } + }); + let obs_json = circuit.get_attr("observables").and_then(|a| { + if let Attribute::String(s) = a { + Some(s.clone()) + } else { + None + } + }); + let num_meas = circuit.get_attr("num_measurements").and_then(|a| { + if let Attribute::String(s) = a { + s.parse::().ok() + } else { + None + } + }); + + let builder = DemBuilder::new(&influence_map).with_noise(p1, p2, p_meas, p_prep); + + let builder = if let Some(ref dj) = det_json { + builder + .with_detectors_json(dj) + .unwrap_or_else(|_| DemBuilder::new(&influence_map).with_noise(p1, p2, p_meas, p_prep)) + } else { + builder + }; + + let builder = if let Some(ref oj) = obs_json { + builder + .with_observables_json(oj) + .unwrap_or_else(|_| DemBuilder::new(&influence_map).with_noise(p1, p2, p_meas, p_prep)) + } else if !annotated_observable_records.is_empty() { + builder.with_observable_records(annotated_observable_records) + } else { + builder + }; + + let builder = if let Some(n) = num_meas { + builder.with_num_measurements(n) + } else { + builder + }; + + builder.build() +} + +fn observable_records_from_annotations( + circuit: &pecos_quantum::DagCircuit, + influence_map: &DagFaultInfluenceMap, +) -> Vec> { + use pecos_quantum::AnnotationKind; + + let num_measurements = influence_map.measurements.len(); + if num_measurements == 0 { + return Vec::new(); + } + + let mut node_to_meas_idx: BTreeMap = BTreeMap::new(); + for (meas_idx, &(node, _qubit, _basis)) in influence_map.measurements.iter().enumerate() { + node_to_meas_idx.entry(node).or_insert(meas_idx); + } + + circuit + .observables() + .map(|ann| { + if let AnnotationKind::Observable { measurement_nodes } = &ann.kind { + measurement_nodes + .iter() + .filter_map(|node| node_to_meas_idx.get(node).copied()) + .map(|meas_idx| { + #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] + { + meas_idx as i32 - num_measurements as i32 + } + }) + .collect() + } else { + Vec::new() + } + }) + .collect() +} + // ============================================================================ // Error Type // ============================================================================ @@ -878,11 +1353,387 @@ impl std::error::Error for DemBuilderError {} mod tests { use super::*; + #[test] + fn test_from_circuit_tracks_pauli_operator_as_tracked_op() { + use pecos_core::pauli::constructors::X; + use pecos_quantum::DagCircuit; + + let mut circuit = DagCircuit::new(); + circuit.pz(&[0]); + circuit.h(&[0]); + circuit.pauli_operator_labeled("x_check", X(0)); + + let dem = DemBuilder::from_circuit(&circuit, 0.03, 0.0, 0.0, 0.0); + + assert_eq!(dem.num_dem_outputs(), 0); + assert_eq!(dem.num_tracked_ops(), 1); + assert_eq!(dem.num_observables(), 0); + assert_eq!( + dem.tracked_ops()[0].kind, + Some(crate::fault_tolerance::DemOutputKind::TrackedOperator) + ); + assert_eq!(dem.tracked_ops()[0].label.as_deref(), Some("x_check")); + assert_eq!( + dem.tracked_ops()[0].pauli.as_ref().unwrap().to_sparse_str(), + "+X0" + ); + assert!(!dem.to_string().contains("logical_observable")); + assert!(dem.to_pecos_string().contains("pecos_tracked_op")); + } + + #[test] + fn test_pauli_operator_and_observable_use_distinct_tracked_ops() { + use pecos_core::pauli::constructors::Z; + use pecos_quantum::{Attribute, DagCircuit}; + + let mut circuit = DagCircuit::new(); + circuit.pz(&[0]); + circuit.pauli_operator_labeled("z_check", Z(0)); + circuit.mz(&[0]); + circuit.set_attr("num_measurements", Attribute::String("1".to_string())); + circuit.set_attr( + "observables", + Attribute::String(r#"[{"id":0,"records":[-1]}]"#.to_string()), + ); + + let dem = DemBuilder::from_circuit(&circuit, 0.0, 0.0, 0.02, 0.03); + + assert_eq!(dem.num_dem_outputs(), 1); + assert_eq!(dem.num_tracked_ops(), 1); + assert_eq!(dem.num_observables(), 1); + assert_eq!( + dem.dem_outputs()[0].kind, + Some(crate::fault_tolerance::DemOutputKind::Observable) + ); + assert_eq!(dem.tracked_ops()[0].label.as_deref(), Some("z_check")); + let dem_str = dem.to_string(); + assert!(dem_str.contains("logical_observable L0")); + assert!(!dem_str.contains("logical_observable L1")); + assert!(dem.to_pecos_string().contains("pecos_tracked_op")); + let summaries = dem.contribution_effect_summaries(); + assert!( + summaries + .iter() + .any(|summary| summary.effect.dem_outputs.as_slice() == [0]), + "observable should remain L0" + ); + } + + #[test] + fn test_from_tick_circuit_tracks_face_gate_fault_sources() { + use pecos_core::QubitId; + use pecos_quantum::{Attribute, TickCircuit}; + + for gate_type in [GateType::F, GateType::Fdg] { + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[QubitId(0)]); + match gate_type { + GateType::F => { + circuit.tick().f(&[QubitId(0)]); + } + GateType::Fdg => { + circuit.tick().fdg(&[QubitId(0)]); + } + _ => unreachable!(), + } + circuit.tick().mz(&[QubitId(0)]); + circuit.set_meta("num_measurements", Attribute::String("1".to_string())); + circuit.set_meta( + "detectors", + Attribute::String(r#"[{"id":0,"records":[-1]}]"#.to_string()), + ); + circuit.set_meta("observables", Attribute::String("[]".to_string())); + + let dem = DemBuilder::from_tick_circuit(&circuit, 0.03, 0.0, 0.0, 0.0); + let contributions = dem.contributions_for_effect(&[0], &[]); + + assert!( + contributions + .iter() + .any(|contribution| contribution.source_gate_types.contains(&gate_type)), + "DEM should include a tracked {gate_type:?} fault source" + ); + } + } + + #[test] + fn test_fault_catalog_and_dem_cover_standard_clifford_gate_sources() { + use crate::fault_tolerance::fault_sampler::{ + FaultCatalog, StochasticNoiseParams, build_fault_catalog, + }; + use pecos_core::QubitId; + use pecos_quantum::{Attribute, TickCircuit}; + use std::collections::BTreeMap; + + fn set_meta(circuit: &mut TickCircuit, num_measurements: usize, detectors: &str) { + circuit.set_meta( + "num_measurements", + Attribute::String(num_measurements.to_string()), + ); + circuit.set_meta("detectors", Attribute::String(detectors.to_string())); + circuit.set_meta("observables", Attribute::String("[]".to_string())); + } + + fn add_1q_gate(circuit: &mut TickCircuit, gate_type: GateType) { + match gate_type { + GateType::X => { + circuit.tick().x(&[QubitId(0)]); + } + GateType::Y => { + circuit.tick().y(&[QubitId(0)]); + } + GateType::Z => { + circuit.tick().z(&[QubitId(0)]); + } + GateType::H => { + circuit.tick().h(&[QubitId(0)]); + } + GateType::F => { + circuit.tick().f(&[QubitId(0)]); + } + GateType::Fdg => { + circuit.tick().fdg(&[QubitId(0)]); + } + GateType::SX => { + circuit.tick().sx(&[QubitId(0)]); + } + GateType::SXdg => { + circuit.tick().sxdg(&[QubitId(0)]); + } + GateType::SY => { + circuit.tick().sy(&[QubitId(0)]); + } + GateType::SYdg => { + circuit.tick().sydg(&[QubitId(0)]); + } + GateType::SZ => { + circuit.tick().sz(&[QubitId(0)]); + } + GateType::SZdg => { + circuit.tick().szdg(&[QubitId(0)]); + } + _ => panic!("not a 1q standard Clifford gate: {gate_type:?}"), + } + } + + fn add_2q_gate(circuit: &mut TickCircuit, gate_type: GateType) { + let pair = &[(QubitId(0), QubitId(1))]; + match gate_type { + GateType::CX => { + circuit.tick().cx(pair); + } + GateType::CY => { + circuit.tick().cy(pair); + } + GateType::CZ => { + circuit.tick().cz(pair); + } + GateType::SXX => { + circuit.tick().sxx(pair); + } + GateType::SXXdg => { + circuit.tick().sxxdg(pair); + } + GateType::SYY => { + circuit.tick().syy(pair); + } + GateType::SYYdg => { + circuit.tick().syydg(pair); + } + GateType::SZZ => { + circuit.tick().szz(pair); + } + GateType::SZZdg => { + circuit.tick().szzdg(pair); + } + GateType::SWAP => { + circuit.tick().swap(pair); + } + _ => panic!("not a 2q standard Clifford gate: {gate_type:?}"), + } + } + + fn dem_has_source(dem: &DetectorErrorModel, gate_type: GateType) -> bool { + dem.contribution_render_records() + .iter() + .any(|record| record.contribution.source_gate_types.contains(&gate_type)) + } + + fn catalog_dem_channel_effect_probabilities( + catalog: &FaultCatalog, + ) -> BTreeMap<(Vec, Vec), f64> { + let mut by_effect = BTreeMap::new(); + for location in &catalog.locations { + if location.num_alternatives == 0 { + continue; + } + let per_channel_probability = 1.0 + - location + .no_fault_probability + .powf(1.0 / location.num_alternatives as f64); + for fault in &location.faults { + if fault.affected_detectors.is_empty() && fault.affected_observables.is_empty() + { + continue; + } + let detectors: Vec = fault + .affected_detectors + .iter() + .map(|&det| u32::try_from(det).unwrap()) + .collect(); + let observables: Vec = fault + .affected_observables + .iter() + .map(|&obs| u32::try_from(obs).unwrap()) + .collect(); + *by_effect.entry((detectors, observables)).or_insert(0.0) += + per_channel_probability; + } + } + by_effect + } + + fn dem_effect_probabilities( + dem: &DetectorErrorModel, + ) -> BTreeMap<(Vec, Vec), f64> { + dem.contribution_effect_summaries() + .into_iter() + .filter(|summary| { + !summary.effect.detectors.is_empty() || !summary.effect.dem_outputs.is_empty() + }) + .map(|summary| { + ( + ( + summary.effect.detectors.into_iter().collect(), + summary.effect.dem_outputs.into_iter().collect(), + ), + summary.total_probability, + ) + }) + .collect() + } + + fn assert_catalog_dem_probabilities_match( + catalog: &FaultCatalog, + dem: &DetectorErrorModel, + gate_type: GateType, + ) { + let catalog_probs = catalog_dem_channel_effect_probabilities(catalog); + let dem_probs = dem_effect_probabilities(dem); + assert_eq!( + catalog_probs.keys().collect::>(), + dem_probs.keys().collect::>(), + "{gate_type:?} should produce the same non-empty effects in the fault catalog and DEM" + ); + for (effect, catalog_probability) in catalog_probs { + let dem_probability = dem_probs[&effect]; + assert!( + (catalog_probability - dem_probability).abs() < 1e-12, + "{gate_type:?} effect {effect:?}: catalog probability {catalog_probability} != DEM probability {dem_probability}" + ); + } + } + + for gate_type in [ + GateType::X, + GateType::Y, + GateType::Z, + GateType::H, + GateType::F, + GateType::Fdg, + GateType::SX, + GateType::SXdg, + GateType::SY, + GateType::SYdg, + GateType::SZ, + GateType::SZdg, + ] { + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[QubitId(0)]); + add_1q_gate(&mut circuit, gate_type); + circuit.tick().mz(&[QubitId(0)]); + set_meta(&mut circuit, 1, r#"[{"id":0,"records":[-1]}]"#); + + let catalog = build_fault_catalog( + &circuit, + &StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + let locations: Vec<_> = catalog + .locations + .iter() + .filter(|location| location.gate_type == gate_type) + .collect(); + assert_eq!(locations.len(), 1, "{gate_type:?}"); + assert_eq!(locations[0].faults.len(), 3, "{gate_type:?}"); + + let dem = DemBuilder::from_tick_circuit(&circuit, 0.03, 0.0, 0.0, 0.0); + assert!( + dem_has_source(&dem, gate_type), + "DEM should track a source contribution for {gate_type:?}" + ); + assert_catalog_dem_probabilities_match(&catalog, &dem, gate_type); + } + + for gate_type in [ + GateType::CX, + GateType::CY, + GateType::CZ, + GateType::SXX, + GateType::SXXdg, + GateType::SYY, + GateType::SYYdg, + GateType::SZZ, + GateType::SZZdg, + GateType::SWAP, + ] { + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[QubitId(0), QubitId(1)]); + add_2q_gate(&mut circuit, gate_type); + circuit.tick().mz(&[QubitId(0), QubitId(1)]); + set_meta( + &mut circuit, + 2, + r#"[{"id":0,"records":[-2]},{"id":1,"records":[-1]}]"#, + ); + + let catalog = build_fault_catalog( + &circuit, + &StochasticNoiseParams { + p1: 0.0, + p2: 0.15, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + let locations: Vec<_> = catalog + .locations + .iter() + .filter(|location| location.gate_type == gate_type) + .collect(); + assert_eq!(locations.len(), 1, "{gate_type:?}"); + assert_eq!(locations[0].faults.len(), 15, "{gate_type:?}"); + + let dem = DemBuilder::from_tick_circuit(&circuit, 0.0, 0.15, 0.0, 0.0); + assert!( + dem_has_source(&dem, gate_type), + "DEM should track a source contribution for {gate_type:?}" + ); + assert_catalog_dem_probabilities_match(&catalog, &dem, gate_type); + } + } + #[test] fn test_parse_detectors_json() { let json = r#"[ {"id": 0, "coords": [0.0, 0.0, 0.0], "records": [-1, -5]}, - {"id": 1, "coords": [1.0, 0.0, 0.0], "records": [-2]} + {"detector_id": 1, "coords": [1.0, 0.0, 0.0], "records": [-2]} ]"#; let detectors = parse_detectors_json(json).unwrap(); @@ -897,7 +1748,7 @@ mod tests { #[test] fn test_parse_observables_json() { - let json = r#"[{"id": 0, "records": [-1, -3, -5]}]"#; + let json = r#"[{"observable_id": 0, "records": [-1, -3, -5]}]"#; let observables = parse_observables_json(json).unwrap(); @@ -906,6 +1757,20 @@ mod tests { assert_eq!(observables[0].records, vec![-1, -3, -5]); } + #[test] + fn test_dem_builder_accepts_observables_json_alias() { + let influence_map = DagFaultInfluenceMap::with_capacity(0); + let dem = DemBuilder::new(&influence_map) + .with_observables_json(r#"[{"id": 0, "records": [-1, -3]}]"#) + .unwrap() + .build(); + + assert_eq!(dem.num_dem_outputs(), 1); + assert_eq!(dem.num_observables(), 1); + assert_eq!(dem.num_tracked_ops(), 0); + assert_eq!(dem.dem_outputs()[0].records.as_slice(), &[-1, -3]); + } + #[test] fn test_parse_empty_json() { assert!(parse_detectors_json("").unwrap().is_empty()); diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index b296a0618..d79c58fb6 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -10,10 +10,17 @@ // or implied. See the License for the specific language governing permissions and limitations under // the License. +//! Internal sampling engine for threshold estimation. +//! +//! This is the core CSR/geometric-skip engine used by [`super::DemSampler`]. +//! External consumers should use `DemSampler` and `DemSamplerBuilder` from +//! the parent module. +#![allow(dead_code)] // Many methods are public for internal use but not called externally yet + //! Fast DEM-style sampler for threshold estimation. //! //! This module provides a sampler that aggregates fault effects directly into -//! detector/observable signatures, matching Stim's DEM sampler semantics. +//! detector/`L` target signatures, matching Stim's DEM sampler semantics. //! //! # Data-Oriented Design //! @@ -21,8 +28,8 @@ //! cache-efficient sampling: //! //! - **Probabilities**: Stored in a contiguous array for sequential access -//! - **Detector/Observable indices**: CSR layout (offsets + flat data) for variable-length lists -//! - **Bit-packed outcomes**: Uses `u64` words for compact detector/observable state +//! - **Detector/`L` target indices**: CSR layout (offsets + flat data) for variable-length lists +//! - **Bit-packed outcomes**: Uses `u64` words for compact detector/`L` state //! //! # Example //! @@ -30,8 +37,7 @@ //! use pecos_qec::fault_tolerance::DagFaultAnalyzer; //! use pecos_qec::fault_tolerance::dem_builder::DemSamplerBuilder; //! use pecos_quantum::DagCircuit; -//! use rand::SeedableRng; -//! use rand::rngs::SmallRng; +//! use pecos_random::PecosRng; //! //! let mut dag = DagCircuit::new(); //! dag.pz(&[2]); @@ -41,19 +47,18 @@ //! //! let analyzer = DagFaultAnalyzer::new(&dag); //! let influence_map = analyzer.build_influence_map(); -//! let detectors_json = r#"[{"id": 0, "records": [-1]}]"#; -//! let observables_json = "[]"; //! -//! // Build from circuit with detector definitions +//! // Build sampler with detector definitions //! let sampler = DemSamplerBuilder::new(&influence_map) //! .with_noise(0.01, 0.01, 0.01, 0.01) -//! .with_detectors_json(detectors_json).unwrap() -//! .with_observables_json(observables_json).unwrap() -//! .build(); +//! .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#).unwrap() +//! .with_observables_json("[]").unwrap() +//! .build() +//! .unwrap(); //! //! // Fast batch sampling for threshold estimation -//! let mut rng = SmallRng::seed_from_u64(42); -//! let (det_events, obs_flips) = sampler.sample_batch(100, &mut rng); +//! let mut rng = PecosRng::seed_from_u64(42); +//! let (det_events, dem_output_flips) = sampler.sample_batch(100, &mut rng); //! ``` use crate::fault_tolerance::propagator::{DagFaultInfluenceMap, Pauli}; @@ -71,35 +76,35 @@ use super::types::combine_probabilities; // DEM Mechanism (used during building) // ============================================================================ -/// A single error mechanism with its detector/observable effects. +/// A single fault mechanism with its detector and `L` target effects. /// Used during building, then converted to `SoA` layout. #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] struct DemMechanism { /// Sorted detector indices that flip when this mechanism fires. detectors: SmallVec<[u32; 4]>, - /// Sorted observable indices that flip when this mechanism fires. - observables: SmallVec<[u32; 2]>, + /// Sorted `L` target indices that flip when this mechanism fires. + dem_outputs: SmallVec<[u32; 2]>, } impl DemMechanism { - fn new(mut detectors: SmallVec<[u32; 4]>, mut observables: SmallVec<[u32; 2]>) -> Self { + fn new(mut detectors: SmallVec<[u32; 4]>, mut dem_outputs: SmallVec<[u32; 2]>) -> Self { detectors.sort_unstable(); - observables.sort_unstable(); + dem_outputs.sort_unstable(); Self { detectors, - observables, + dem_outputs, } } fn empty() -> Self { Self { detectors: SmallVec::new(), - observables: SmallVec::new(), + dem_outputs: SmallVec::new(), } } fn is_empty(&self) -> bool { - self.detectors.is_empty() && self.observables.is_empty() + self.detectors.is_empty() && self.dem_outputs.is_empty() } } @@ -169,13 +174,13 @@ impl PackedBits { /// Fast DEM-style sampler for threshold estimation. /// /// Uses Structure of Arrays (`SoA`) layout with CSR-style indexing for -/// cache-efficient sampling. Detector and observable outcomes are bit-packed +/// cache-efficient sampling. Detector and `L` target outcomes are bit-packed /// for compact storage and fast XOR operations. /// /// # Data-Oriented Design /// /// - **Precomputed thresholds**: Probabilities converted to u64 thresholds at build time -/// - **CSR layout**: Detector/observable indices in flat arrays with offsets +/// - **CSR layout**: Detector/`L` target indices in flat arrays with offsets /// - **Bit-packed outcomes**: Uses u64 words for compact XOR operations /// - **Batch RNG**: Can use bulk random number generation for cache efficiency /// @@ -185,15 +190,15 @@ impl PackedBits { /// thresholds: [t0, t1, t2, ...] (precomputed u64, sequential read) /// detector_offsets: [0, 2, 3, 5, ...] (CSR row pointers) /// detector_data: [d0, d1, d2, d3, d4, ...] (flat detector indices) -/// observable_offsets: [0, 0, 1, 1, ...] (CSR row pointers) -/// observable_data: [o0, ...] (flat observable indices) +/// dem_output_offsets: [0, 0, 1, 1, ...] (CSR row pointers) +/// dem_output_data: [t0, ...] (flat `L` target indices) /// ``` /// /// For mechanism i: /// - Detector indices: `detector_data[detector_offsets[i]..detector_offsets[i+1]]` -/// - Observable indices: `observable_data[observable_offsets[i]..observable_offsets[i+1]]` +/// - Tracked-op indices: `dem_output_data[dem_output_offsets[i]..dem_output_offsets[i+1]]` #[derive(Debug, Clone)] -pub struct DemSampler { +pub struct SamplingEngine { // SoA layout for cache efficiency /// Precomputed u64 thresholds (faster than f64 comparison). thresholds: Vec, @@ -207,18 +212,19 @@ pub struct DemSampler { /// Flat array of detector indices. detector_data: Vec, - /// CSR-style offsets into `observable_data`. Length = `num_mechanisms` + 1. - observable_offsets: Vec, - /// Flat array of observable indices. - observable_data: Vec, + /// CSR-style offsets into `dem_output_data`. Length = `num_mechanisms` + 1. + /// These are Stim-compatible `L` DEM outputs. + dem_output_offsets: Vec, + /// Flat array of `L` target indices. + dem_output_data: Vec, /// Number of detectors. num_detectors: usize, - /// Number of observables. - num_observables: usize, + /// Number of DEM `L` outputs. + num_dem_outputs: usize, } -impl DemSampler { +impl SamplingEngine { /// Number of mechanisms in the sampler. #[must_use] pub fn num_mechanisms(&self) -> usize { @@ -231,25 +237,34 @@ impl DemSampler { self.num_detectors } - /// Number of observables. + /// Number of observables in a pure Stim DEM. + /// + /// Parsed Stim DEMs do not carry PECOS tracked-operator metadata, so every + /// `L` output is treated as an observable. #[must_use] pub fn num_observables(&self) -> usize { - self.num_observables + self.num_dem_outputs + } + + /// Number of DEM `L` outputs. + #[must_use] + pub fn num_dem_outputs(&self) -> usize { + self.num_dem_outputs } - /// Create a [`DemSampler`] from raw mechanism data. + /// Create a [`SamplingEngine`] from raw mechanism data. /// /// This constructor is used when building from a parsed DEM string rather than /// from a circuit analysis. Each mechanism is specified by its probability and - /// the detector/observable indices it affects. + /// the detector/`L` target indices it affects. /// /// # Arguments /// - /// * `mechanisms` - Iterator of (probability, `detector_indices`, `observable_indices`) + /// * `mechanisms` - Iterator of (probability, `detector_indices`, `dem_output_indices`) /// * `num_detectors` - Total number of detectors - /// * `num_observables` - Total number of observables + /// * `num_dem_outputs` - Total number of standard observable `L` outputs #[must_use] - pub fn from_mechanisms(mechanisms: I, num_detectors: usize, num_observables: usize) -> Self + pub fn from_mechanisms(mechanisms: I, num_detectors: usize, num_dem_outputs: usize) -> Self where I: IntoIterator, Vec)>, { @@ -260,16 +275,16 @@ impl DemSampler { let mut inv_log_1_minus_p = Vec::with_capacity(num_mechanisms); let mut detector_offsets = Vec::with_capacity(num_mechanisms + 1); let mut detector_data = Vec::new(); - let mut observable_offsets = Vec::with_capacity(num_mechanisms + 1); - let mut observable_data = Vec::new(); + let mut dem_output_offsets = Vec::with_capacity(num_mechanisms + 1); + let mut dem_output_data = Vec::new(); detector_offsets.push(0); - observable_offsets.push(0); + dem_output_offsets.push(0); - for (prob, mut detectors, mut observables) in mechanisms { + for (prob, mut detectors, mut dem_outputs) in mechanisms { // Sort for canonical representation detectors.sort_unstable(); - observables.sort_unstable(); + dem_outputs.sort_unstable(); // Precompute u64 threshold: p * u64::MAX #[allow( @@ -293,9 +308,9 @@ impl DemSampler { #[allow(clippy::cast_possible_truncation)] // detector data length fits in u32 detector_offsets.push(detector_data.len() as u32); - observable_data.extend_from_slice(&observables); - #[allow(clippy::cast_possible_truncation)] // observable data length fits in u32 - observable_offsets.push(observable_data.len() as u32); + dem_output_data.extend_from_slice(&dem_outputs); + #[allow(clippy::cast_possible_truncation)] // `L` target data length fits in u32 + dem_output_offsets.push(dem_output_data.len() as u32); } Self { @@ -303,20 +318,153 @@ impl DemSampler { inv_log_1_minus_p, detector_offsets, detector_data, - observable_offsets, - observable_data, + dem_output_offsets, + dem_output_data, num_detectors, - num_observables, + num_dem_outputs, + } + } + + /// Create a [`SamplingEngine`] directly from a [`DagFaultInfluenceMap`] and + /// per-location error probabilities. + /// + /// Each fault location is treated as depolarizing: probability `p` at + /// location `i` means X, Y, and Z faults each occur with probability + /// `p/3`. Mechanisms with identical detector/`L` target effects are + /// aggregated automatically. + /// + /// This constructor works with the influence map's raw measurement and + /// DEM-output indices — no explicit detector or observable metadata + /// definitions are needed. + /// + /// # Arguments + /// + /// * `influence_map` - Precomputed fault influence map. + /// * `per_location_probs` - Error probability for each per-qubit fault location + /// (length must equal `influence_map.locations.len()`). + /// + /// Uses the per-gate noise model: each gate faults with probability p, + /// and each non-identity Pauli is equally likely (p/3 for 1-qubit, + /// p/15 for 2-qubit). For idle gates with T1/T2 noise, the Pauli + /// distribution is biased (more Z than X/Y). + #[must_use] + pub fn from_influence_map( + influence_map: &DagFaultInfluenceMap, + per_location_probs: &[f64], + noise: &super::NoiseConfig, + ) -> Self { + use pecos_core::gate_type::GateType; + + let mut aggregated: BTreeMap = BTreeMap::new(); + + let gate_locs = influence_map.gate_fault_locations(); + + for loc in &gate_locs { + let p = super::sampler::gate_location_prob_from_locations( + loc, + per_location_probs, + &influence_map.locations, + ); + if p <= 0.0 { + continue; + } + + let events = loc.all_events(); + if events.is_empty() { + continue; + } + + // For idle gates with T1/T2 noise, use per-Pauli probabilities. + // For all other gates, divide equally among events. + let is_idle = loc.gate_type == GateType::Idle; + let idle_pauli_probs = if is_idle { + let duration = influence_map + .locations + .iter() + .find(|l| l.node == loc.node && l.before == loc.before) + .map_or(1, |l| l.idle_duration.max(1)); + // Duration values are small integers; precision loss is not a concern. + #[allow(clippy::cast_precision_loss)] + Some(noise.idle_pauli_probs(duration as f64)) + } else { + None + }; + + // Get per-event probabilities based on gate type and noise config + let n_qubits = loc.num_qubits(); + let custom_weights = if idle_pauli_probs.is_some() { + None + } else if n_qubits == 1 { + noise.p1_weights.as_ref() + } else { + noise.p2_weights.as_ref() + }; + + let event_weights: Vec = if let Some(pp) = &idle_pauli_probs { + // T1/T2 idle: absolute per-Pauli probabilities + events + .iter() + .map(|event| { + let pauli = event + .pauli + .paulis() + .first() + .map_or(pecos_core::Pauli::I, |&(pa, _)| pa); + match pauli { + pecos_core::Pauli::X => pp.px, + pecos_core::Pauli::Y => pp.py, + pecos_core::Pauli::Z => pp.pz, + pecos_core::Pauli::I => 0.0, + } + }) + .collect() + } else if let Some(weights) = custom_weights { + // Custom per-Pauli weights: p * weight_for(pauli) + events + .iter() + .map(|event| p * weights.weight_for(&event.pauli)) + .collect() + } else { + // Default uniform: p / num_events + // Event count is a small integer; precision loss is not a concern. + #[allow(clippy::cast_precision_loss)] + let per_event = p / events.len() as f64; + vec![per_event; events.len()] + }; + + for (event, &event_prob) in events.iter().zip(&event_weights) { + let det_indices: SmallVec<[u32; 4]> = event.detectors.iter().copied().collect(); + let dem_output_indices: SmallVec<[u32; 2]> = event + .dem_outputs + .iter() + .filter_map(|&idx| influence_map.observable_id_for_internal_dem_output(idx)) + .collect(); + + let mech = DemMechanism::new(det_indices, dem_output_indices); + if !mech.is_empty() { + let entry = aggregated.entry(mech).or_insert(0.0); + *entry = combine_probabilities(*entry, event_prob); + } + } } + + let num_detectors = influence_map.detectors.len(); + let num_dem_outputs = influence_map.num_dem_outputs(); + + let mechanisms = aggregated + .into_iter() + .map(|(mech, prob)| (prob, mech.detectors.to_vec(), mech.dem_outputs.to_vec())); + + Self::from_mechanisms(mechanisms, num_detectors, num_dem_outputs) } /// Sample a single shot. /// - /// Returns (`detection_events`, `observable_flips`) as boolean vectors. + /// Returns (`detection_events`, `dem_output_flips`) as boolean vectors. #[must_use] pub fn sample(&self, rng: &mut R) -> (Vec, Vec) { let mut det_bits = PackedBits::new(self.num_detectors); - let mut obs_bits = PackedBits::new(self.num_observables); + let mut obs_bits = PackedBits::new(self.num_dem_outputs); self.sample_into_packed(&mut det_bits, &mut obs_bits, rng); @@ -341,16 +489,16 @@ impl DemSampler { for i in 0..num_mechanisms { // Fast integer comparison with precomputed threshold if rng.check_probability(self.thresholds[i]) { - // Mechanism fired - XOR in detector/observable effects + // Mechanism fired - XOR in detector/`L` target effects let det_start = self.detector_offsets[i] as usize; let det_end = self.detector_offsets[i + 1] as usize; for &d in &self.detector_data[det_start..det_end] { det_bits.flip(d as usize); } - let obs_start = self.observable_offsets[i] as usize; - let obs_end = self.observable_offsets[i + 1] as usize; - for &o in &self.observable_data[obs_start..obs_end] { + let obs_start = self.dem_output_offsets[i] as usize; + let obs_end = self.dem_output_offsets[i + 1] as usize; + for &o in &self.dem_output_data[obs_start..obs_end] { obs_bits.flip(o as usize); } } @@ -359,24 +507,66 @@ impl DemSampler { /// Sample multiple shots. /// - /// Returns (`all_detection_events`, `all_observable_flips`). + /// Uses geometric skip sampling internally — O(fired mechanisms) per + /// shot instead of O(all mechanisms). Automatically converts from + /// columnar bit-packed format to row-major `Vec`. + /// + /// Returns (`all_detection_events`, `all_dem_output_flips`). #[must_use] pub fn sample_batch( &self, num_shots: usize, rng: &mut R, ) -> (Vec>, Vec>) { - let mut all_det_events = Vec::with_capacity(num_shots); - let mut all_obs_flips = Vec::with_capacity(num_shots); + if num_shots == 0 { + return (vec![], vec![]); + } - // Pre-allocate work arrays - let mut det_bits = PackedBits::new(self.num_detectors); - let mut obs_bits = PackedBits::new(self.num_observables); + // Sample using geometric skip (fast at low error rates). + let (det_columns, obs_columns) = self.sample_batch_columnar_geometric(num_shots, rng); - for _ in 0..num_shots { - self.sample_into_packed(&mut det_bits, &mut obs_bits, rng); - all_det_events.push(det_bits.to_vec()); - all_obs_flips.push(obs_bits.to_vec()); + // Convert columnar bit-packed → row-major Vec. + let mut all_det_events: Vec> = (0..num_shots) + .map(|_| vec![false; self.num_detectors]) + .collect(); + let mut all_obs_flips: Vec> = (0..num_shots) + .map(|_| vec![false; self.num_dem_outputs]) + .collect(); + + for (det_idx, col) in det_columns.iter().enumerate() { + for (word_idx, &word) in col.iter().enumerate() { + if word == 0 { + continue; + } + let base_shot = word_idx * BITS_PER_WORD; + let mut w = word; + while w != 0 { + let bit = w.trailing_zeros() as usize; + let shot = base_shot + bit; + if shot < num_shots { + all_det_events[shot][det_idx] = true; + } + w &= w - 1; + } + } + } + + for (obs_idx, col) in obs_columns.iter().enumerate() { + for (word_idx, &word) in col.iter().enumerate() { + if word == 0 { + continue; + } + let base_shot = word_idx * BITS_PER_WORD; + let mut w = word; + while w != 0 { + let bit = w.trailing_zeros() as usize; + let shot = base_shot + bit; + if shot < num_shots { + all_obs_flips[shot][obs_idx] = true; + } + w &= w - 1; + } + } } (all_det_events, all_obs_flips) @@ -411,6 +601,31 @@ impl DemSampler { self.sample_statistics_auto_internal(&mut rng, num_shots) } + /// Compute statistics where only the specified DEM outputs count as observables. + /// + /// The sampler still reports per-DEM-output flip counts for every `L` + /// output. `logical_error_count` and `undetectable_count` are computed + /// from the selected observable outputs only, so tracked-operator probes do + /// not affect decoder-style observable statistics. + #[must_use] + pub fn sample_statistics_for_observable_indices( + &self, + num_shots: usize, + seed: u64, + observable_indices: &[usize], + ) -> SamplingStatistics { + if self.all_dem_outputs_selected(observable_indices) { + return self.sample_statistics(num_shots, seed); + } + + let mut rng = PecosRng::seed_from_u64(seed); + self.sample_statistics_with_rng_for_observable_indices( + num_shots, + &mut rng, + observable_indices, + ) + } + /// Compute statistics with a user-provided RNG. /// /// Use this when you need control over the random number generator, @@ -429,6 +644,43 @@ impl DemSampler { self.sample_statistics_auto_internal(rng, num_shots) } + /// Compute statistics with a user-provided RNG and explicit observable DEM-output indices. + #[must_use] + pub fn sample_statistics_with_rng_for_observable_indices( + &self, + num_shots: usize, + rng: &mut R, + observable_indices: &[usize], + ) -> SamplingStatistics { + if self.all_dem_outputs_selected(observable_indices) { + return self.sample_statistics_with_rng(num_shots, rng); + } + if num_shots == 0 || self.thresholds.is_empty() { + return SamplingStatistics::with_channels( + num_shots, + self.num_detectors, + self.num_dem_outputs, + ); + } + + let (det_columns, dem_output_columns) = + self.sample_batch_columnar_geometric(num_shots, rng); + Self::compute_statistics_from_columns_for_observables( + &det_columns, + &dem_output_columns, + num_shots, + observable_indices, + ) + } + + fn all_dem_outputs_selected(&self, observable_indices: &[usize]) -> bool { + observable_indices.len() == self.num_dem_outputs + && observable_indices + .iter() + .copied() + .eq(0..self.num_dem_outputs) + } + /// Internal: sample statistics using the most efficient method. /// /// Uses chunked processing for large working sets (>6 MB) to improve cache @@ -445,7 +697,7 @@ impl DemSampler { /// Optimized statistics sampling using flat array layout. /// /// This method provides faster sampling than nested Vec> by: - /// - Using a flat contiguous array for detector/observable columns + /// - Using a flat contiguous array for detector/`L` target columns /// - Better cache locality due to predictable memory access patterns /// /// This method is semantically equivalent to the columnar methods. @@ -461,9 +713,9 @@ impl DemSampler { // XOR semantics required for correct detector behavior let mut det_data: Vec = vec![0u64; self.num_detectors * num_words]; - // Flat array for observable columns (XOR semantics) + // Flat array for `L` target columns (XOR semantics) // Layout: obs_data[obs_idx * num_words + word_idx] - let mut obs_data: Vec = vec![0u64; self.num_observables * num_words]; + let mut obs_data: Vec = vec![0u64; self.num_dem_outputs * num_words]; for mech_idx in 0..num_mechanisms { let threshold = self.thresholds[mech_idx]; @@ -473,8 +725,8 @@ impl DemSampler { let det_start = self.detector_offsets[mech_idx] as usize; let det_end = self.detector_offsets[mech_idx + 1] as usize; - let obs_start = self.observable_offsets[mech_idx] as usize; - let obs_end = self.observable_offsets[mech_idx + 1] as usize; + let obs_start = self.dem_output_offsets[mech_idx] as usize; + let obs_end = self.dem_output_offsets[mech_idx + 1] as usize; // Skip if mechanism affects nothing if det_start == det_end && obs_start == obs_end { @@ -507,7 +759,7 @@ impl DemSampler { } // XOR each affected observable - for &o in &self.observable_data[obs_start..obs_end] { + for &o in &self.dem_output_data[obs_start..obs_end] { let idx = o as usize * num_words + word_idx; obs_data[idx] ^= mask; } @@ -525,20 +777,62 @@ impl DemSampler { } } - // Compute logical error mask by ORing all observable columns - let mut logical_words = vec![0u64; num_words]; - for obs_idx in 0..self.num_observables { + // Compute logical-error mask by ORing all selected standard observable columns. + let mut observable_words = vec![0u64; num_words]; + for obs_idx in 0..self.num_dem_outputs { let base = obs_idx * num_words; for word_idx in 0..num_words { - logical_words[word_idx] |= obs_data[base + word_idx]; + observable_words[word_idx] |= obs_data[base + word_idx]; } } // Count statistics - let mut stats = SamplingStatistics::new(num_shots); + let mut stats = + SamplingStatistics::with_channels(num_shots, self.num_detectors, self.num_dem_outputs); + + // Per-channel counts (cheap -- data is already in cache from the OR passes above) + for det_idx in 0..self.num_detectors { + let base = det_idx * num_words; + let mut count = 0usize; + for word_idx in 0..num_words { + let valid_bits = if word_idx == num_words - 1 { + let remaining = num_shots % BITS_PER_WORD; + if remaining == 0 { + !0u64 + } else { + (1u64 << remaining) - 1 + } + } else { + !0u64 + }; + count += (det_data[base + word_idx] & valid_bits).count_ones() as usize; + } + stats.per_detector[det_idx] = count; + } + + for obs_idx in 0..self.num_dem_outputs { + let base = obs_idx * num_words; + let mut count = 0usize; + for word_idx in 0..num_words { + let valid_bits = if word_idx == num_words - 1 { + let remaining = num_shots % BITS_PER_WORD; + if remaining == 0 { + !0u64 + } else { + (1u64 << remaining) - 1 + } + } else { + !0u64 + }; + count += (obs_data[base + word_idx] & valid_bits).count_ones() as usize; + } + stats.per_dem_output[obs_idx] = count; + } + + // Aggregate counts for word_idx in 0..num_words { let syndrome = syndrome_words[word_idx]; - let logical = logical_words[word_idx]; + let observable = observable_words[word_idx]; let valid_bits = if word_idx == num_words - 1 { let remaining = num_shots % BITS_PER_WORD; @@ -552,11 +846,12 @@ impl DemSampler { }; let syndrome_masked = syndrome & valid_bits; - let logical_masked = logical & valid_bits; + let observable_masked = observable & valid_bits; stats.syndrome_count += syndrome_masked.count_ones() as usize; - stats.logical_error_count += logical_masked.count_ones() as usize; - stats.undetectable_count += (logical_masked & !syndrome_masked).count_ones() as usize; + stats.logical_error_count += observable_masked.count_ones() as usize; + stats.undetectable_count += + (observable_masked & !syndrome_masked).count_ones() as usize; } stats @@ -568,9 +863,9 @@ impl DemSampler { /// within the target cache size (L3). Returns `None` if the buffer is already /// small enough that chunking wouldn't help. fn optimal_chunk_size(&self, num_shots: usize) -> Option { - // Calculate full buffer size: (num_detectors + num_observables) * num_words * 8 bytes + // Calculate full buffer size: (num_detectors + num_dem_outputs) * num_words * 8 bytes let num_words = num_shots.div_ceil(BITS_PER_WORD); - let full_buffer_bytes = (self.num_detectors + self.num_observables) * num_words * 8; + let full_buffer_bytes = (self.num_detectors + self.num_dem_outputs) * num_words * 8; // Only chunk if buffer exceeds target cache size if full_buffer_bytes <= TARGET_CHUNK_BUFFER_BYTES { @@ -578,9 +873,9 @@ impl DemSampler { } // Calculate chunk size that fits in cache - // Buffer = (num_detectors + num_observables) * (chunk_shots / 64) * 8 - // chunk_shots = TARGET * 64 / ((num_detectors + num_observables) * 8) - let total_columns = self.num_detectors + self.num_observables; + // Buffer = (num_detectors + num_dem_outputs) * (chunk_shots / 64) * 8 + // chunk_shots = TARGET * 64 / ((num_detectors + num_dem_outputs) * 8) + let total_columns = self.num_detectors + self.num_dem_outputs; if total_columns == 0 { return None; } @@ -616,7 +911,8 @@ impl DemSampler { return self.sample_statistics_direct(num_shots, rng); }; - let mut total_stats = SamplingStatistics::new(num_shots); + let mut total_stats = + SamplingStatistics::with_channels(num_shots, self.num_detectors, self.num_dem_outputs); let mut shot_offset = 0; while shot_offset < num_shots { @@ -626,6 +922,20 @@ impl DemSampler { total_stats.syndrome_count += chunk_stats.syndrome_count; total_stats.logical_error_count += chunk_stats.logical_error_count; total_stats.undetectable_count += chunk_stats.undetectable_count; + for (total, chunk) in total_stats + .per_detector + .iter_mut() + .zip(&chunk_stats.per_detector) + { + *total += chunk; + } + for (total, chunk) in total_stats + .per_dem_output + .iter_mut() + .zip(&chunk_stats.per_dem_output) + { + *total += chunk; + } shot_offset += chunk_shots; } @@ -641,26 +951,39 @@ impl DemSampler { num_shots: usize, rng: &mut R, ) -> SamplingStatistics { - let mut stats = SamplingStatistics::new(num_shots); + let mut stats = + SamplingStatistics::with_channels(num_shots, self.num_detectors, self.num_dem_outputs); let mut det_bits = PackedBits::new(self.num_detectors); - let mut obs_bits = PackedBits::new(self.num_observables); + let mut obs_bits = PackedBits::new(self.num_dem_outputs); for _ in 0..num_shots { self.sample_into_packed(&mut det_bits, &mut obs_bits, rng); let has_syndrome = det_bits.any(); - let has_logical_error = obs_bits.any(); + let has_observable_error = obs_bits.any(); - if has_logical_error { + if has_observable_error { stats.logical_error_count += 1; } if has_syndrome { stats.syndrome_count += 1; } - if has_logical_error && !has_syndrome { + if has_observable_error && !has_syndrome { stats.undetectable_count += 1; } + + // Per-channel counts + for (i, count) in stats.per_detector.iter_mut().enumerate() { + if det_bits.get(i) { + *count += 1; + } + } + for (i, count) in stats.per_dem_output.iter_mut().enumerate() { + if obs_bits.get(i) { + *count += 1; + } + } } stats @@ -675,7 +998,7 @@ impl DemSampler { /// This method processes all shots for each mechanism at once, enabling: /// - Bulk random number generation (64 shots per u64) /// - Better cache locality for threshold comparisons - /// - Vectorized XOR operations on detector/observable columns + /// - Vectorized XOR operations on detector/`L` target columns /// /// Returns columnar bit-packed results: (detector_columns, observable_columns) /// where each column is a Vec with bit i of word w = shot w*64 + i. @@ -689,17 +1012,17 @@ impl DemSampler { if num_shots == 0 { return ( vec![vec![]; self.num_detectors], - vec![vec![]; self.num_observables], + vec![vec![]; self.num_dem_outputs], ); } let num_words = num_shots.div_ceil(BITS_PER_WORD); - // Initialize detector and observable columns (all zeros) + // Initialize detector and `L` target columns (all zeros) let mut det_columns: Vec> = (0..self.num_detectors) .map(|_| vec![0u64; num_words]) .collect(); - let mut obs_columns: Vec> = (0..self.num_observables) + let mut obs_columns: Vec> = (0..self.num_dem_outputs) .map(|_| vec![0u64; num_words]) .collect(); @@ -716,9 +1039,7 @@ impl DemSampler { } // Generate bulk random numbers for this mechanism - for word in &mut random_words { - *word = rng.next_u64(); - } + rng.fill_u64(&mut random_words); // For each word, check threshold and apply effects for word_idx in 0..num_words { @@ -737,10 +1058,10 @@ impl DemSampler { det_columns[d as usize][word_idx] ^= !0u64; } - // XOR effects into observable columns - let obs_start = self.observable_offsets[mech_idx] as usize; - let obs_end = self.observable_offsets[mech_idx + 1] as usize; - for &o in &self.observable_data[obs_start..obs_end] { + // XOR effects into `L` target columns + let obs_start = self.dem_output_offsets[mech_idx] as usize; + let obs_end = self.dem_output_offsets[mech_idx + 1] as usize; + for &o in &self.dem_output_data[obs_start..obs_end] { obs_columns[o as usize][word_idx] ^= !0u64; } } @@ -763,17 +1084,17 @@ impl DemSampler { if num_shots == 0 { return ( vec![vec![]; self.num_detectors], - vec![vec![]; self.num_observables], + vec![vec![]; self.num_dem_outputs], ); } let num_words = num_shots.div_ceil(BITS_PER_WORD); - // Initialize detector and observable columns (all zeros) + // Initialize detector and `L` target columns (all zeros) let mut det_columns: Vec> = (0..self.num_detectors) .map(|_| vec![0u64; num_words]) .collect(); - let mut obs_columns: Vec> = (0..self.num_observables) + let mut obs_columns: Vec> = (0..self.num_dem_outputs) .map(|_| vec![0u64; num_words]) .collect(); @@ -786,11 +1107,11 @@ impl DemSampler { continue; } - // Get detector/observable indices for this mechanism + // Get detector/`L` target indices for this mechanism let det_start = self.detector_offsets[mech_idx] as usize; let det_end = self.detector_offsets[mech_idx + 1] as usize; - let obs_start = self.observable_offsets[mech_idx] as usize; - let obs_end = self.observable_offsets[mech_idx + 1] as usize; + let obs_start = self.dem_output_offsets[mech_idx] as usize; + let obs_end = self.dem_output_offsets[mech_idx + 1] as usize; // For each word (64 shots), generate random bits and check threshold for word_idx in 0..num_words { @@ -824,8 +1145,8 @@ impl DemSampler { det_columns[d as usize][word_idx] ^= fired_mask; } - // XOR the fired mask into affected observable columns - for &o in &self.observable_data[obs_start..obs_end] { + // XOR the fired mask into affected `L` target columns + for &o in &self.dem_output_data[obs_start..obs_end] { obs_columns[o as usize][word_idx] ^= fired_mask; } } @@ -858,18 +1179,18 @@ impl DemSampler { } } - // OR all observable columns to get logical error mask - let mut logical_words = vec![0u64; num_words]; + // OR all standard observable columns to get a logical-error mask. + let mut observable_words = vec![0u64; num_words]; for col in &obs_columns { for (i, &word) in col.iter().enumerate() { - logical_words[i] |= word; + observable_words[i] |= word; } } - // Count shots with syndrome, logical error, undetectable + // Count shots with syndrome, logical error, undetectable error for word_idx in 0..num_words { let syndrome = syndrome_words[word_idx]; - let logical = logical_words[word_idx]; + let observable = observable_words[word_idx]; // Mask out unused bits in the last word let valid_bits = if word_idx == num_words - 1 { @@ -884,11 +1205,12 @@ impl DemSampler { }; let syndrome_masked = syndrome & valid_bits; - let logical_masked = logical & valid_bits; + let observable_masked = observable & valid_bits; stats.syndrome_count += syndrome_masked.count_ones() as usize; - stats.logical_error_count += logical_masked.count_ones() as usize; - stats.undetectable_count += (logical_masked & !syndrome_masked).count_ones() as usize; + stats.logical_error_count += observable_masked.count_ones() as usize; + stats.undetectable_count += + (observable_masked & !syndrome_masked).count_ones() as usize; } stats @@ -911,18 +1233,18 @@ impl DemSampler { if num_shots == 0 { return ( vec![vec![]; self.num_detectors], - vec![vec![]; self.num_observables], + vec![vec![]; self.num_dem_outputs], ); } let num_words = num_shots.div_ceil(BITS_PER_WORD); let num_simd_words = num_words.div_ceil(4); - // Initialize detector and observable columns as SIMD vectors + // Initialize detector and `L` target columns as SIMD vectors let mut det_columns: Vec> = (0..self.num_detectors) .map(|_| vec![u64x4::ZERO; num_simd_words]) .collect(); - let mut obs_columns: Vec> = (0..self.num_observables) + let mut obs_columns: Vec> = (0..self.num_dem_outputs) .map(|_| vec![u64x4::ZERO; num_simd_words]) .collect(); @@ -937,11 +1259,11 @@ impl DemSampler { continue; } - // Get detector/observable indices for this mechanism + // Get detector/`L` target indices for this mechanism let det_start = self.detector_offsets[mech_idx] as usize; let det_end = self.detector_offsets[mech_idx + 1] as usize; - let obs_start = self.observable_offsets[mech_idx] as usize; - let obs_end = self.observable_offsets[mech_idx + 1] as usize; + let obs_start = self.dem_output_offsets[mech_idx] as usize; + let obs_end = self.dem_output_offsets[mech_idx + 1] as usize; // Generate all random numbers for this mechanism at once // Use fill_u64 from RngProbabilityExt for potentially optimized bulk generation @@ -995,8 +1317,8 @@ impl DemSampler { det_columns[d as usize][simd_idx] ^= fired_vec; } - // XOR into affected observable columns - for &o in &self.observable_data[obs_start..obs_end] { + // XOR into affected `L` target columns + for &o in &self.dem_output_data[obs_start..obs_end] { obs_columns[o as usize][simd_idx] ^= fired_vec; } } @@ -1060,17 +1382,17 @@ impl DemSampler { if num_shots == 0 { return ( vec![vec![]; self.num_detectors], - vec![vec![]; self.num_observables], + vec![vec![]; self.num_dem_outputs], ); } let num_words = num_shots.div_ceil(BITS_PER_WORD); - // Initialize detector and observable columns + // Initialize detector and `L` target columns let mut det_columns: Vec> = (0..self.num_detectors) .map(|_| vec![0u64; num_words]) .collect(); - let mut obs_columns: Vec> = (0..self.num_observables) + let mut obs_columns: Vec> = (0..self.num_dem_outputs) .map(|_| vec![0u64; num_words]) .collect(); @@ -1082,11 +1404,11 @@ impl DemSampler { continue; } - // Get detector/observable indices + // Get detector/`L` target indices let det_start = self.detector_offsets[mech_idx] as usize; let det_end = self.detector_offsets[mech_idx + 1] as usize; - let obs_start = self.observable_offsets[mech_idx] as usize; - let obs_end = self.observable_offsets[mech_idx + 1] as usize; + let obs_start = self.dem_output_offsets[mech_idx] as usize; + let obs_end = self.dem_output_offsets[mech_idx + 1] as usize; // Use precomputed 1/ln(1-p) for geometric sampling let inv_log = self.inv_log_1_minus_p[mech_idx]; @@ -1115,7 +1437,7 @@ impl DemSampler { det_columns[d as usize][word_idx] ^= mask; } - for &o in &self.observable_data[obs_start..obs_end] { + for &o in &self.dem_output_data[obs_start..obs_end] { obs_columns[o as usize][word_idx] ^= mask; } @@ -1221,11 +1543,18 @@ impl DemSampler { .collect(); // Sum up partial statistics - let mut total = SamplingStatistics::new(num_shots); + let mut total = + SamplingStatistics::with_channels(num_shots, self.num_detectors, self.num_dem_outputs); for stats in partial_stats { total.syndrome_count += stats.syndrome_count; total.logical_error_count += stats.logical_error_count; total.undetectable_count += stats.undetectable_count; + for (t, s) in total.per_detector.iter_mut().zip(&stats.per_detector) { + *t += s; + } + for (t, s) in total.per_dem_output.iter_mut().zip(&stats.per_dem_output) { + *t += s; + } } total @@ -1249,30 +1578,75 @@ impl DemSampler { det_columns: &[Vec], obs_columns: &[Vec], num_shots: usize, + ) -> SamplingStatistics { + let observable_indices: Vec = (0..obs_columns.len()).collect(); + Self::compute_statistics_from_columns_for_observables( + det_columns, + obs_columns, + num_shots, + &observable_indices, + ) + } + + fn compute_statistics_from_columns_for_observables( + det_columns: &[Vec], + obs_columns: &[Vec], + num_shots: usize, + observable_indices: &[usize], ) -> SamplingStatistics { let num_words = num_shots.div_ceil(BITS_PER_WORD); - let mut stats = SamplingStatistics::new(num_shots); + let mut stats = + SamplingStatistics::with_channels(num_shots, det_columns.len(), obs_columns.len()); - // OR all detector columns to get syndrome mask + // Per-channel and aggregate syndrome let mut syndrome_words = vec![0u64; num_words]; - for col in det_columns { + for (det_idx, col) in det_columns.iter().enumerate() { + let mut count = 0usize; for (i, &word) in col.iter().enumerate() { syndrome_words[i] |= word; + let valid = if i == num_words - 1 { + let r = num_shots % BITS_PER_WORD; + if r == 0 { !0u64 } else { (1u64 << r) - 1 } + } else { + !0u64 + }; + count += (word & valid).count_ones() as usize; } + stats.per_detector[det_idx] = count; } - // OR all observable columns to get logical error mask - let mut logical_words = vec![0u64; num_words]; - for col in obs_columns { + // Per-channel DEM-output counts. + let mut dem_output_words = vec![vec![0u64; num_words]; obs_columns.len()]; + for (obs_idx, col) in obs_columns.iter().enumerate() { + let mut count = 0usize; for (i, &word) in col.iter().enumerate() { - logical_words[i] |= word; + dem_output_words[obs_idx][i] = word; + let valid = if i == num_words - 1 { + let r = num_shots % BITS_PER_WORD; + if r == 0 { !0u64 } else { (1u64 << r) - 1 } + } else { + !0u64 + }; + count += (word & valid).count_ones() as usize; + } + stats.per_dem_output[obs_idx] = count; + } + + // Aggregate logical-error mask from observables only. Tracked + // operators remain in per_dem_output but do not define decoder failures. + let mut observable_words = vec![0u64; num_words]; + for &obs_idx in observable_indices { + if let Some(col) = dem_output_words.get(obs_idx) { + for (i, &word) in col.iter().enumerate() { + observable_words[i] |= word; + } } } - // Count shots with syndrome, logical error, undetectable + // Aggregate counts for word_idx in 0..num_words { let syndrome = syndrome_words[word_idx]; - let logical = logical_words[word_idx]; + let observable = observable_words[word_idx]; let valid_bits = if word_idx == num_words - 1 { let remaining = num_shots % BITS_PER_WORD; @@ -1286,11 +1660,12 @@ impl DemSampler { }; let syndrome_masked = syndrome & valid_bits; - let logical_masked = logical & valid_bits; + let observable_masked = observable & valid_bits; stats.syndrome_count += syndrome_masked.count_ones() as usize; - stats.logical_error_count += logical_masked.count_ones() as usize; - stats.undetectable_count += (logical_masked & !syndrome_masked).count_ones() as usize; + stats.logical_error_count += observable_masked.count_ones() as usize; + stats.undetectable_count += + (observable_masked & !syndrome_masked).count_ones() as usize; } stats @@ -1302,12 +1677,16 @@ impl DemSampler { pub struct SamplingStatistics { /// Total number of shots. pub total_shots: usize, - /// Shots with at least one logical error. + /// Shots with at least one selected observable flip. pub logical_error_count: usize, /// Shots with at least one detector firing. pub syndrome_count: usize, - /// Shots with logical error but no syndrome (undetectable errors). + /// Shots with an observable flip but no syndrome. pub undetectable_count: usize, + /// Per-detector firing counts (shots where this detector fired). + pub per_detector: Vec, + /// Per-`L` DEM-output flip counts (shots where this `L` output flipped). + pub per_dem_output: Vec, } impl SamplingStatistics { @@ -1317,52 +1696,108 @@ impl SamplingStatistics { logical_error_count: 0, syndrome_count: 0, undetectable_count: 0, + per_detector: Vec::new(), + per_dem_output: Vec::new(), + } + } + + fn with_channels(total_shots: usize, num_detectors: usize, num_dem_outputs: usize) -> Self { + Self { + total_shots, + logical_error_count: 0, + syndrome_count: 0, + undetectable_count: 0, + per_detector: vec![0; num_detectors], + per_dem_output: vec![0; num_dem_outputs], } } /// Logical error rate. #[must_use] - #[allow(clippy::cast_precision_loss)] // rate calculation + #[allow(clippy::cast_precision_loss)] pub fn logical_error_rate(&self) -> f64 { self.logical_error_count as f64 / self.total_shots as f64 } /// Syndrome rate (fraction of shots with non-trivial syndrome). #[must_use] - #[allow(clippy::cast_precision_loss)] // rate calculation + #[allow(clippy::cast_precision_loss)] pub fn syndrome_rate(&self) -> f64 { self.syndrome_count as f64 / self.total_shots as f64 } /// Undetectable error rate. #[must_use] - #[allow(clippy::cast_precision_loss)] // rate calculation + #[allow(clippy::cast_precision_loss)] pub fn undetectable_rate(&self) -> f64 { self.undetectable_count as f64 / self.total_shots as f64 } + + /// Per-detector firing rates. + #[must_use] + #[allow(clippy::cast_precision_loss)] + pub fn detector_rates(&self) -> Vec { + let n = self.total_shots as f64; + self.per_detector.iter().map(|&c| c as f64 / n).collect() + } + + /// Per-`L` DEM-output flip rates. + #[must_use] + #[allow(clippy::cast_precision_loss)] + pub fn dem_output_rates(&self) -> Vec { + let n = self.total_shots as f64; + self.per_dem_output.iter().map(|&c| c as f64 / n).collect() + } + + /// Per-`L` DEM-output flip counts. + #[must_use] + pub fn dem_output_counts(&self) -> &[usize] { + &self.per_dem_output + } + + /// Per-observable flip counts selected from standard `L` observable columns. + #[must_use] + pub fn observable_counts(&self, observable_indices: &[usize]) -> Vec { + observable_indices + .iter() + .filter_map(|&idx| self.per_dem_output.get(idx).copied()) + .collect() + } + + /// Per-observable flip rates selected from standard `L` observable columns. + #[must_use] + #[allow(clippy::cast_precision_loss)] + pub fn logical_rates(&self, observable_indices: &[usize]) -> Vec { + let n = self.total_shots as f64; + self.observable_counts(observable_indices) + .into_iter() + .map(|c| c as f64 / n) + .collect() + } } // ============================================================================ // DEM Sampler Builder // ============================================================================ -/// Builder for [`DemSampler`]. +/// Builder for [`SamplingEngine`]. /// -/// Constructs a [`DemSampler`] from a fault influence map, noise parameters, -/// and explicit detector/observable definitions. -pub struct DemSamplerBuilder<'a> { +/// Constructs a [`SamplingEngine`] from a fault influence map, noise parameters, +/// and explicit detector/`L` target definitions. +pub(crate) struct SamplingEngineBuilder<'a> { influence_map: &'a DagFaultInfluenceMap, p1: f64, p2: f64, p_meas: f64, - p_init: f64, + p_prep: f64, + p_idle: Option, detector_records: Vec>, observable_records: Vec>, measurement_order: Option>, num_tc_measurements: Option, } -impl<'a> DemSamplerBuilder<'a> { +impl<'a> SamplingEngineBuilder<'a> { /// Create a new builder from an influence map. #[must_use] pub fn new(influence_map: &'a DagFaultInfluenceMap) -> Self { @@ -1371,7 +1806,8 @@ impl<'a> DemSamplerBuilder<'a> { p1: 0.01, p2: 0.01, p_meas: 0.01, - p_init: 0.01, + p_prep: 0.01, + p_idle: None, detector_records: Vec::new(), observable_records: Vec::new(), measurement_order: None, @@ -1381,11 +1817,18 @@ impl<'a> DemSamplerBuilder<'a> { /// Set noise parameters. #[must_use] - pub fn with_noise(mut self, p1: f64, p2: f64, p_meas: f64, p_init: f64) -> Self { + pub fn with_noise(mut self, p1: f64, p2: f64, p_meas: f64, p_prep: f64) -> Self { self.p1 = p1; self.p2 = p2; self.p_meas = p_meas; - self.p_init = p_init; + self.p_prep = p_prep; + self + } + + /// Set idle gate noise rate. + #[must_use] + pub fn with_idle_noise(mut self, p_idle: f64) -> Self { + self.p_idle = Some(p_idle); self } @@ -1418,7 +1861,7 @@ impl<'a> DemSamplerBuilder<'a> { self } - /// Set observable records directly. + /// Set observable definitions directly. #[must_use] pub fn with_observable_records(mut self, records: Vec>) -> Self { self.observable_records = records; @@ -1436,11 +1879,12 @@ impl<'a> DemSamplerBuilder<'a> { self } - /// Build the [`DemSampler`]. + /// Build the [`SamplingEngine`]. #[must_use] - pub fn build(self) -> DemSampler { + pub fn build(self) -> SamplingEngine { let num_detectors = self.detector_records.len(); - let num_observables = self.observable_records.len(); + let num_influence_observables = self.influence_map.num_dem_outputs(); + let num_dem_outputs = num_influence_observables.max(self.observable_records.len()); let num_im_measurements = self.influence_map.measurements.len(); let num_tc_measurements = self.num_tc_measurements.unwrap_or(num_im_measurements); @@ -1456,39 +1900,52 @@ impl<'a> DemSamplerBuilder<'a> { // Process each fault location for (loc_idx, loc) in self.influence_map.locations.iter().enumerate() { match loc.gate_type { - GateType::PZ | GateType::QAlloc => { + GateType::PZ | GateType::QAlloc // Prep errors: only "after" locations (X error for Z-basis prep) - if self.p_init > 0.0 && !loc.before { + if self.p_prep > 0.0 && !loc.before => { self.process_single_pauli_fault( loc_idx, Pauli::X, - self.p_init, + self.p_prep, im_to_tc.as_deref(), + 0, num_tc_measurements, &mut aggregated, ); } - } - GateType::MZ | GateType::MeasureFree => { + GateType::MZ | GateType::MeasureFree // Measurement errors: only "before" locations (X error = bit flip) - if self.p_meas > 0.0 && loc.before { + if self.p_meas > 0.0 && loc.before => { self.process_single_pauli_fault( loc_idx, Pauli::X, self.p_meas, im_to_tc.as_deref(), + 0, num_tc_measurements, &mut aggregated, ); } - } - GateType::CX | GateType::CZ | GateType::CY | GateType::SWAP => { + GateType::CX + | GateType::CZ + | GateType::CY + | GateType::SZZ + | GateType::SZZdg + | GateType::SXX + | GateType::SXXdg + | GateType::SYY + | GateType::SYYdg + | GateType::SWAP + | GateType::RXX + | GateType::RYY + | GateType::RZZ // Two-qubit gate errors: only "after" locations, process as pairs - if !loc.before { + if !loc.before => { cx_groups.entry(loc.node).or_default().push(loc_idx); } - } GateType::H + | GateType::F + | GateType::Fdg | GateType::SZ | GateType::SZdg | GateType::SX @@ -1497,18 +1954,45 @@ impl<'a> DemSamplerBuilder<'a> { | GateType::SYdg | GateType::X | GateType::Y - | GateType::Z => { + | GateType::Z + | GateType::T + | GateType::Tdg + | GateType::RX + | GateType::RY + | GateType::RZ + | GateType::U + | GateType::R1XY // Single-qubit gate errors: only "after" locations, depolarizing - if self.p1 > 0.0 && !loc.before { + if self.p1 > 0.0 && !loc.before => { self.process_depolarizing_fault( loc_idx, self.p1, im_to_tc.as_deref(), + 0, num_tc_measurements, &mut aggregated, ); } - } + GateType::Idle + // Idle gate errors: only "after" locations, depolarizing. + // Probability scales with duration: p = p_idle_rate * duration, + // clamped to [0, 1]. + if self.p_idle.is_some_and(|p| p > 0.0) && !loc.before => { + // Duration values are small integers; precision loss is not a concern. + #[allow(clippy::cast_precision_loss)] + let duration = loc.idle_duration.max(1) as f64; + let p = (self.p_idle.unwrap() * duration).min(1.0); + if p > 0.0 { + self.process_depolarizing_fault( + loc_idx, + p, + im_to_tc.as_deref(), + 0, + num_tc_measurements, + &mut aggregated, + ); + } + } _ => {} } } @@ -1521,6 +2005,7 @@ impl<'a> DemSamplerBuilder<'a> { loc_indices[0], loc_indices[1], im_to_tc.as_deref(), + 0, num_tc_measurements, &mut aggregated, ); @@ -1533,11 +2018,11 @@ impl<'a> DemSamplerBuilder<'a> { let mut thresholds = Vec::with_capacity(num_mechanisms); let mut detector_offsets = Vec::with_capacity(num_mechanisms + 1); let mut detector_data = Vec::new(); - let mut observable_offsets = Vec::with_capacity(num_mechanisms + 1); - let mut observable_data = Vec::new(); + let mut dem_output_offsets = Vec::with_capacity(num_mechanisms + 1); + let mut dem_output_data = Vec::new(); detector_offsets.push(0); - observable_offsets.push(0); + dem_output_offsets.push(0); let mut inv_log_1_minus_p = Vec::with_capacity(num_mechanisms); @@ -1566,20 +2051,20 @@ impl<'a> DemSamplerBuilder<'a> { #[allow(clippy::cast_possible_truncation)] // detector data length fits in u32 detector_offsets.push(detector_data.len() as u32); - observable_data.extend_from_slice(&mech.observables); - #[allow(clippy::cast_possible_truncation)] // observable data length fits in u32 - observable_offsets.push(observable_data.len() as u32); + dem_output_data.extend_from_slice(&mech.dem_outputs); + #[allow(clippy::cast_possible_truncation)] // `L` target data length fits in u32 + dem_output_offsets.push(dem_output_data.len() as u32); } - DemSampler { + SamplingEngine { thresholds, inv_log_1_minus_p, detector_offsets, detector_data, - observable_offsets, - observable_data, + dem_output_offsets, + dem_output_data, num_detectors, - num_observables, + num_dem_outputs, } } @@ -1623,10 +2108,17 @@ impl<'a> DemSamplerBuilder<'a> { pauli: Pauli, prob: f64, im_to_tc: Option<&[usize]>, + observable_id_offset: usize, num_tc_measurements: usize, aggregated: &mut BTreeMap, ) { - let mechanism = self.compute_mechanism(loc_idx, pauli, im_to_tc, num_tc_measurements); + let mechanism = self.compute_mechanism( + loc_idx, + pauli, + im_to_tc, + observable_id_offset, + num_tc_measurements, + ); if !mechanism.is_empty() { let entry = aggregated.entry(mechanism).or_insert(0.0); *entry = combine_probabilities(*entry, prob); @@ -1639,12 +2131,19 @@ impl<'a> DemSamplerBuilder<'a> { loc_idx: usize, prob: f64, im_to_tc: Option<&[usize]>, + observable_id_offset: usize, num_tc_measurements: usize, aggregated: &mut BTreeMap, ) { let per_pauli_prob = prob / 3.0; for pauli in [Pauli::X, Pauli::Y, Pauli::Z] { - let mechanism = self.compute_mechanism(loc_idx, pauli, im_to_tc, num_tc_measurements); + let mechanism = self.compute_mechanism( + loc_idx, + pauli, + im_to_tc, + observable_id_offset, + num_tc_measurements, + ); if !mechanism.is_empty() { let entry = aggregated.entry(mechanism).or_insert(0.0); *entry = combine_probabilities(*entry, per_pauli_prob); @@ -1658,6 +2157,7 @@ impl<'a> DemSamplerBuilder<'a> { loc1: usize, loc2: usize, im_to_tc: Option<&[usize]>, + observable_id_offset: usize, num_tc_measurements: usize, aggregated: &mut BTreeMap, ) { @@ -1669,10 +2169,20 @@ impl<'a> DemSamplerBuilder<'a> { let mut effects2: [Option; 4] = [None, None, None, None]; for &p in &[Pauli::X, Pauli::Y, Pauli::Z] { - effects1[p as usize] = - Some(self.compute_mechanism(loc1, p, im_to_tc, num_tc_measurements)); - effects2[p as usize] = - Some(self.compute_mechanism(loc2, p, im_to_tc, num_tc_measurements)); + effects1[p as usize] = Some(self.compute_mechanism( + loc1, + p, + im_to_tc, + observable_id_offset, + num_tc_measurements, + )); + effects2[p as usize] = Some(self.compute_mechanism( + loc2, + p, + im_to_tc, + observable_id_offset, + num_tc_measurements, + )); } // Process all 15 non-trivial Pauli combinations @@ -1693,7 +2203,7 @@ impl<'a> DemSamplerBuilder<'a> { .clone() .unwrap_or_else(DemMechanism::empty) } else { - // Correlated: XOR the detector/observable effects + // Correlated: XOR the detector/`L` target effects let e1 = effects1[p1 as usize].as_ref(); let e2 = effects2[p2 as usize].as_ref(); xor_mechanisms(e1, e2) @@ -1707,12 +2217,13 @@ impl<'a> DemSamplerBuilder<'a> { } } - /// Compute the mechanism (detector/observable effects) for a fault. + /// Compute the mechanism (detector/`L` target effects) for a fault. fn compute_mechanism( &self, loc_idx: usize, pauli: Pauli, im_to_tc: Option<&[usize]>, + observable_id_offset: usize, num_tc_measurements: usize, ) -> DemMechanism { // Get measurement indices that flip (in IM order) @@ -1720,6 +2231,14 @@ impl<'a> DemSamplerBuilder<'a> { .influence_map .get_detector_indices(loc_idx, pauli as u8); + let mut dem_outputs: SmallVec<[u32; 2]> = SmallVec::new(); + for dem_output_idx in self + .influence_map + .get_observable_indices(loc_idx, pauli as u8) + { + xor_toggle_u32(&mut dem_outputs, dem_output_idx); + } + // Convert to TC order measurement outcomes let mut tc_outcomes = vec![false; num_tc_measurements]; for &im_idx in im_meas_flips { @@ -1767,48 +2286,55 @@ impl<'a> DemSamplerBuilder<'a> { }) .collect(); - // Apply observable definitions (XOR of measurement outcomes) - let observables: SmallVec<[u32; 2]> = self - .observable_records - .iter() - .enumerate() - .filter_map(|(obs_id, records)| { - let mut xor_result = false; - for &offset in records { - #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] // measurement count fits in i32 - #[allow(clippy::cast_sign_loss)] - // negative offset + total count, or non-negative offset - let abs_idx = if offset < 0 { - (num_tc_measurements as i32 + offset) as usize - } else { - offset as usize - }; - if abs_idx < num_tc_measurements && tc_outcomes[abs_idx] { - xor_result = !xor_result; - } - } - if xor_result { - #[allow(clippy::cast_possible_truncation)] // observable ID fits in u32 - Some(obs_id as u32) + // Apply `L` target definitions (XOR of measurement outcomes) + for (obs_id, records) in self.observable_records.iter().enumerate() { + let mut xor_result = false; + for &offset in records { + #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] // measurement count fits in i32 + #[allow(clippy::cast_sign_loss)] + // negative offset + total count, or non-negative offset + let abs_idx = if offset < 0 { + (num_tc_measurements as i32 + offset) as usize } else { - None + offset as usize + }; + if abs_idx < num_tc_measurements && tc_outcomes[abs_idx] { + xor_result = !xor_result; } - }) - .collect(); + } + if xor_result { + #[allow(clippy::cast_possible_truncation)] // `L` target ID fits in u32 + let obs_idx = (observable_id_offset + obs_id) as u32; + xor_toggle_u32(&mut dem_outputs, obs_idx); + } + } + dem_outputs.sort_unstable(); + + DemMechanism::new(detectors, dem_outputs) + } +} - DemMechanism::new(detectors, observables) +/// Toggles an element in a parity vector. +fn xor_toggle_u32(values: &mut SmallVec<[u32; N]>, value: u32) +where + [u32; N]: smallvec::Array, +{ + if let Some(pos) = values.iter().position(|&v| v == value) { + values.remove(pos); + } else { + values.push(value); } } -/// XORs two [`DemMechanism`]s (symmetric difference of detectors and observables). +/// XORs two [`DemMechanism`]s (symmetric difference of detectors and `L` targets). fn xor_mechanisms(a: Option<&DemMechanism>, b: Option<&DemMechanism>) -> DemMechanism { match (a, b) { (Some(m1), Some(m2)) => { let detectors = xor_u32_vecs::<4>(&m1.detectors, &m2.detectors); - let observables = xor_u32_vecs::<2>(&m1.observables, &m2.observables); + let dem_outputs = xor_u32_vecs::<2>(&m1.dem_outputs, &m2.dem_outputs); DemMechanism { detectors, - observables, + dem_outputs, } } (Some(m), None) | (None, Some(m)) => m.clone(), @@ -1848,7 +2374,7 @@ where result } -/// Parse detector or observable records from JSON. +/// Parse detector or observable definitions from JSON. /// /// Uses a simple custom parser to avoid `serde_json` dependency. /// Expected format: `[{"id": 0, "records": [-1, -5]}, ...]` @@ -1966,8 +2492,8 @@ mod tests { // Detectors: {0,1,2} XOR {1,2,3} = {0,3} assert_eq!(result.detectors.as_slice(), &[0, 3]); - // Observables: {0} XOR {0,1} = {1} - assert_eq!(result.observables.as_slice(), &[1]); + // DEM outputs: {0} XOR {0,1} = {1} + assert_eq!(result.dem_outputs.as_slice(), &[1]); } #[test] @@ -2021,11 +2547,13 @@ mod tests { let influence_map = analyzer.build_influence_map(); // Zero noise should produce no errors - let sampler = DemSamplerBuilder::new(&influence_map) + let sampler = SamplingEngineBuilder::new(&influence_map) .with_noise(0.0, 0.0, 0.0, 0.0) .build(); assert_eq!(sampler.num_mechanisms(), 0); + assert_eq!(sampler.num_dem_outputs(), 0); + assert_eq!(sampler.num_observables(), 0); let stats = sampler.sample_statistics(100, 42); assert_eq!(stats.logical_error_count, 0); @@ -2051,7 +2579,7 @@ mod tests { let detectors_json = r#"[{"id": 0, "records": [-1]}]"#; let observables_json = r"[]"; - let sampler = DemSamplerBuilder::new(&influence_map) + let sampler = SamplingEngineBuilder::new(&influence_map) .with_noise(0.1, 0.1, 0.1, 0.1) .with_detectors_json(detectors_json) .unwrap() @@ -2068,6 +2596,36 @@ mod tests { assert!(stats.syndrome_count > 0); } + #[test] + fn test_sampling_engine_builder_accepts_observable_record_inputs() { + use crate::fault_tolerance::propagator::DagFaultAnalyzer; + use pecos_quantum::DagCircuit; + + let mut dag = DagCircuit::new(); + dag.pz(&[0]); + dag.h(&[0]); + dag.mz(&[0]); + + let analyzer = DagFaultAnalyzer::new(&dag); + let influence_map = analyzer.build_influence_map(); + + let json_sampler = SamplingEngineBuilder::new(&influence_map) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .with_observables_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + assert_eq!(json_sampler.num_detectors(), 1); + assert_eq!(json_sampler.num_dem_outputs(), 1); + + let record_sampler = SamplingEngineBuilder::new(&influence_map) + .with_detector_records(vec![vec![-1]]) + .with_observable_records(vec![vec![-1]]) + .build(); + assert_eq!(record_sampler.num_detectors(), 1); + assert_eq!(record_sampler.num_dem_outputs(), 1); + } + #[test] fn test_columnar_sampling_statistics() { use crate::fault_tolerance::propagator::DagFaultAnalyzer; @@ -2087,7 +2645,7 @@ mod tests { let analyzer = DagFaultAnalyzer::new(&dag); let influence_map = analyzer.build_influence_map(); - let sampler = DemSamplerBuilder::new(&influence_map) + let sampler = SamplingEngineBuilder::new(&influence_map) .with_noise(0.01, 0.01, 0.01, 0.01) .with_detector_records(vec![vec![-1], vec![-2]]) .with_observable_records(vec![]) @@ -2131,7 +2689,7 @@ mod tests { let analyzer = DagFaultAnalyzer::new(&dag); let influence_map = analyzer.build_influence_map(); - let sampler = DemSamplerBuilder::new(&influence_map) + let sampler = SamplingEngineBuilder::new(&influence_map) .with_noise(0.5, 0.0, 0.0, 0.0) // High noise rate for testing .with_detector_records(vec![vec![-1]]) .with_observable_records(vec![]) @@ -2167,7 +2725,7 @@ mod tests { let analyzer = DagFaultAnalyzer::new(&dag); let influence_map = analyzer.build_influence_map(); - let sampler = DemSamplerBuilder::new(&influence_map) + let sampler = SamplingEngineBuilder::new(&influence_map) .with_noise(0.01, 0.01, 0.01, 0.01) .with_detector_records(vec![vec![-1], vec![-2]]) .with_observable_records(vec![]) @@ -2208,7 +2766,7 @@ mod tests { let influence_map = analyzer.build_influence_map(); // Use low noise to exercise geometric sampling effectively - let sampler = DemSamplerBuilder::new(&influence_map) + let sampler = SamplingEngineBuilder::new(&influence_map) .with_noise(0.001, 0.001, 0.001, 0.001) .with_detector_records(vec![vec![-1], vec![-2]]) .with_observable_records(vec![]) @@ -2252,7 +2810,7 @@ mod tests { let influence_map = analyzer.build_influence_map(); // Low error rate - should use geometric - let sampler = DemSamplerBuilder::new(&influence_map) + let sampler = SamplingEngineBuilder::new(&influence_map) .with_noise(0.001, 0.001, 0.001, 0.001) .with_detector_records(vec![vec![-1]]) .with_observable_records(vec![]) @@ -2282,7 +2840,7 @@ mod tests { let influence_map = analyzer.build_influence_map(); // High error rate - should use SIMD - let sampler = DemSamplerBuilder::new(&influence_map) + let sampler = SamplingEngineBuilder::new(&influence_map) .with_noise(0.1, 0.1, 0.1, 0.1) .with_detector_records(vec![vec![-1]]) .with_observable_records(vec![]) @@ -2314,7 +2872,7 @@ mod tests { let analyzer = DagFaultAnalyzer::new(&dag); let influence_map = analyzer.build_influence_map(); - let sampler = DemSamplerBuilder::new(&influence_map) + let sampler = SamplingEngineBuilder::new(&influence_map) .with_noise(0.001, 0.001, 0.001, 0.001) .with_detector_records(vec![vec![-1], vec![-2]]) .with_observable_records(vec![]) @@ -2349,7 +2907,7 @@ mod tests { #[test] fn test_from_mechanisms_empty() { - let sampler = DemSampler::from_mechanisms(std::iter::empty(), 0, 0); + let sampler = SamplingEngine::from_mechanisms(std::iter::empty(), 0, 0); assert_eq!(sampler.num_mechanisms(), 0); assert_eq!(sampler.num_detectors(), 0); assert_eq!(sampler.num_observables(), 0); @@ -2363,7 +2921,7 @@ mod tests { fn test_from_mechanisms_single_detector() { // Single mechanism that flips D0 with p=0.5 let mechanisms = vec![(0.5, vec![0u32], vec![])]; - let sampler = DemSampler::from_mechanisms(mechanisms, 1, 0); + let sampler = SamplingEngine::from_mechanisms(mechanisms, 1, 0); assert_eq!(sampler.num_mechanisms(), 1); assert_eq!(sampler.num_detectors(), 1); @@ -2381,7 +2939,7 @@ mod tests { fn test_from_mechanisms_multiple_detectors() { // Two mechanisms: D0 with p=0.1, D1 with p=0.2 let mechanisms = vec![(0.1, vec![0u32], vec![]), (0.2, vec![1u32], vec![])]; - let sampler = DemSampler::from_mechanisms(mechanisms, 2, 0); + let sampler = SamplingEngine::from_mechanisms(mechanisms, 2, 0); assert_eq!(sampler.num_mechanisms(), 2); assert_eq!(sampler.num_detectors(), 2); @@ -2399,7 +2957,7 @@ mod tests { fn test_from_mechanisms_correlated_detectors() { // Single mechanism that flips both D0 and D1 together with p=0.3 let mechanisms = vec![(0.3, vec![0u32, 1u32], vec![])]; - let sampler = DemSampler::from_mechanisms(mechanisms, 2, 0); + let sampler = SamplingEngine::from_mechanisms(mechanisms, 2, 0); assert_eq!(sampler.num_mechanisms(), 1); assert_eq!(sampler.num_detectors(), 2); @@ -2418,7 +2976,7 @@ mod tests { // Two mechanisms that both flip D0 with the same probability // When both fire, they XOR and cancel let mechanisms = vec![(0.5, vec![0u32], vec![]), (0.5, vec![0u32], vec![])]; - let sampler = DemSampler::from_mechanisms(mechanisms, 1, 0); + let sampler = SamplingEngine::from_mechanisms(mechanisms, 1, 0); // With two independent p=0.5 mechanisms that both flip D0: // P(D0 fires) = P(exactly one fires) = 2 * 0.5 * 0.5 = 0.5 @@ -2431,15 +2989,21 @@ mod tests { } #[test] - fn test_from_mechanisms_with_observables() { + fn test_from_mechanisms_with_tracked_ops() { // Mechanism that flips D0 and L0 let mechanisms = vec![(0.1, vec![0u32], vec![0u32])]; - let sampler = DemSampler::from_mechanisms(mechanisms, 1, 1); + let sampler = SamplingEngine::from_mechanisms(mechanisms, 1, 1); - assert_eq!(sampler.num_observables(), 1); + assert_eq!(sampler.num_dem_outputs(), 1); // Logical error rate should be approximately 0.1 let stats = sampler.sample_statistics(10000, 42); + assert_eq!(stats.dem_output_counts(), stats.per_dem_output.as_slice()); + assert_eq!( + stats.observable_counts(&[0]).as_slice(), + stats.per_dem_output.as_slice() + ); + assert_eq!(stats.logical_rates(&[0]), stats.dem_output_rates()); let logical_rate = stats.logical_error_rate(); assert!( (logical_rate - 0.1).abs() < 0.03, @@ -2451,7 +3015,7 @@ mod tests { fn test_from_mechanisms_very_low_error_rate() { // Test geometric sampling efficiency with low error rate let mechanisms = vec![(0.0001, vec![0u32], vec![])]; - let sampler = DemSampler::from_mechanisms(mechanisms, 1, 0); + let sampler = SamplingEngine::from_mechanisms(mechanisms, 1, 0); // Should still work correctly let stats = sampler.sample_statistics(100_000, 42); @@ -2466,11 +3030,12 @@ mod tests { fn test_from_mechanisms_sorting() { // Verify that detector indices are sorted regardless of input order let mechanisms = vec![(0.1, vec![2u32, 0u32, 1u32], vec![1u32, 0u32])]; - let sampler = DemSampler::from_mechanisms(mechanisms, 3, 2); + let sampler = SamplingEngine::from_mechanisms(mechanisms, 3, 2); // Verify internal storage is sorted (by checking that sampling works) assert_eq!(sampler.num_detectors(), 3); assert_eq!(sampler.num_observables(), 2); + assert_eq!(sampler.num_dem_outputs(), 2); let stats = sampler.sample_statistics(1000, 42); // Just verify it runs without panicking diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs index 2fd419f38..2912979a8 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs @@ -18,7 +18,7 @@ //! # Key Concepts //! //! - Two DEMs are equivalent if they produce the same probability distribution -//! over (`detector_events`, `observable_flips`) patterns. +//! over (`detector_events`, `dem_output_flips`) patterns. //! - Decomposed DEMs (using ^) create independent error channels that are `XORed`. //! - Different decomposition strategies can produce equivalent sampling results. //! - For non-decomposed DEMs, mechanisms must match exactly. @@ -58,13 +58,13 @@ use std::collections::{BTreeMap, BTreeSet}; use std::fmt; use std::str::FromStr; -use super::types::combine_probabilities; +use super::types::{DemOutput, combine_probabilities, parse_pecos_dem_metadata_line}; // ============================================================================ // Parsed DEM Types // ============================================================================ -/// A single error mechanism parsed from DEM format. +/// A single fault mechanism parsed from DEM format. /// /// Can represent both simple mechanisms (D0 D1) and decomposed ones (D0 ^ D1). #[derive(Debug, Clone)] @@ -134,6 +134,26 @@ impl ParsedMechanism { observables: obs, } } + + /// Format the target string for this mechanism (e.g., "D0 D3 L0" or "D0 ^ D1 D3"). + #[must_use] + pub fn format_targets(&self) -> String { + let parts: Vec = self + .components + .iter() + .map(|comp| { + let mut tokens = Vec::new(); + for &d in &comp.detectors { + tokens.push(format!("D{d}")); + } + for &o in &comp.observables { + tokens.push(format!("L{o}")); + } + tokens.join(" ") + }) + .collect(); + parts.join(" ^ ") + } } /// A single component of a mechanism (the part between ^ separators). @@ -195,8 +215,12 @@ pub struct ParsedDem { pub mechanisms: Vec, /// Number of detectors (max ID + 1). pub num_detectors: u32, - /// Number of observables (max ID + 1). - pub num_observables: u32, + /// Total number of outputs in the DEM `L` namespace. + pub num_dem_outputs: u32, + /// PECOS metadata for `L` observables, indexed by `L`. + pub dem_outputs: Vec>, + /// PECOS metadata for tracked operators in their own ID space. + pub tracked_ops: Vec>, } impl ParsedDem { @@ -206,7 +230,9 @@ impl ParsedDem { Self { mechanisms: Vec::new(), num_detectors: 0, - num_observables: 0, + num_dem_outputs: 0, + dem_outputs: Vec::new(), + tracked_ops: Vec::new(), } } @@ -221,6 +247,32 @@ impl ParsedDem { dem_str.parse() } + /// Total number of outputs in the DEM `L` namespace. + #[must_use] + pub fn num_dem_outputs(&self) -> u32 { + self.num_dem_outputs + } + + /// Number of observables. + #[must_use] + pub fn num_observables(&self) -> u32 { + self.num_dem_outputs + } + + /// Number of tracked operators. + #[must_use] + pub fn num_tracked_ops(&self) -> u32 { + self.tracked_ops.iter().flatten().count() as u32 + } + + fn record_metadata(ops: &mut Vec>, op: DemOutput) { + let idx = op.id as usize; + if ops.len() <= idx { + ops.resize(idx + 1, None); + } + ops[idx] = Some(op); + } + /// Parses a single error line. fn parse_error_line(line: &str) -> Result { // Extract probability: error(0.01) ... @@ -343,7 +395,7 @@ impl ParsedDem { /// Samples from this DEM. /// - /// Returns (`detector_events`, `observable_flips`). + /// Returns (`detector_events`, `dem_output_flips`). /// /// # Semantics /// @@ -353,7 +405,7 @@ impl ParsedDem { /// independent firing - all components fire together as a single error. pub fn sample(&self, rng: &mut R) -> (Vec, Vec) { let mut det_events = vec![false; self.num_detectors as usize]; - let mut obs_flips = vec![false; self.num_observables as usize]; + let mut obs_flips = vec![false; self.num_dem_outputs as usize]; for mech in &self.mechanisms { // Single random check for the entire mechanism @@ -379,7 +431,7 @@ impl ParsedDem { /// Samples multiple shots from this DEM. /// - /// Returns (`detector_events_per_shot`, `observable_flips_per_shot`). + /// Returns (`detector_events_per_shot`, `dem_output_flips_per_shot`). pub fn sample_batch( &self, num_shots: usize, @@ -413,8 +465,8 @@ impl ParsedDem { /// used for error tracking/decomposition but doesn't affect sampling - all /// components fire together. #[must_use] - pub fn to_dem_sampler(&self) -> super::dem_sampler::DemSampler { - // Convert mechanisms to the format expected by DemSampler::from_mechanisms + pub fn to_dem_sampler(&self) -> super::sampler::DemSampler { + // Convert mechanisms to the format expected by SamplingEngine::from_mechanisms // Use combined_effect() to get the union of all detectors/observables // since all components fire together when the error occurs let mechanisms = self.mechanisms.iter().map(|mech| { @@ -422,11 +474,80 @@ impl ParsedDem { (mech.probability, dets, obs) }); - super::dem_sampler::DemSampler::from_mechanisms( + let engine = super::dem_sampler::SamplingEngine::from_mechanisms( mechanisms, self.num_detectors as usize, - self.num_observables as usize, - ) + self.num_dem_outputs as usize, + ); + super::sampler::DemSampler::from_engine(engine) + } + + /// Convert to a decomposed (graphlike) DEM string. + /// + /// Mechanisms with <= 2 detectors pass through unchanged. Already-decomposed + /// mechanisms (with `^` notation) pass through unchanged. + /// + /// Hyperedges (3+ detectors, not already decomposed) cannot be decomposed + /// without Pauli provenance and will cause an error. Use + /// `coherent_dem_decomposed()` or `noise_characterization()` for proper + /// X/Z-aware decomposition. + /// + /// # Errors + /// + /// Returns an error if any mechanism has 3+ detectors without decomposition. + pub fn to_string_decomposed(&self) -> Result { + let mut lines = Vec::new(); + + // Accumulate by target string to merge identical decomposed entries + let mut by_targets: BTreeMap = BTreeMap::new(); + + for mech in &self.mechanisms { + if mech.probability <= 0.0 { + continue; + } + + if mech.is_decomposed() { + // Already decomposed — pass through + let targets = mech.format_targets(); + by_targets + .entry(targets) + .and_modify(|p| *p = combine_probabilities(*p, mech.probability)) + .or_insert(mech.probability); + continue; + } + + // Single component + let comp = &mech.components[0]; + + if comp.detectors.len() <= 2 { + // Graphlike — pass through + let targets = mech.format_targets(); + by_targets + .entry(targets) + .and_modify(|p| *p = combine_probabilities(*p, mech.probability)) + .or_insert(mech.probability); + } else { + // Hyperedge (3+ detectors) cannot be decomposed without Pauli + // provenance (X/Z component info). Use `coherent_dem_decomposed()` + // or `noise_characterization()` which track X/Z components from + // the backward mechanism extraction. + return Err(format!( + "Cannot decompose hyperedge with {} detectors ({:?}) without \ + Pauli provenance. Use coherent_dem_decomposed() or \ + noise_characterization() for proper X/Z decomposition.", + comp.detectors.len(), + comp.detectors, + )); + } + } + + for (targets, prob) in &by_targets { + if *prob > 0.0 { + lines.push(format!("error({prob}) {targets}")); + } + } + + Ok(lines.join("\n")) } } @@ -443,6 +564,8 @@ impl FromStr for ParsedDem { let mut mechanisms = Vec::new(); let mut max_det: i32 = -1; let mut max_obs: i32 = -1; + let mut dem_outputs: Vec> = Vec::new(); + let mut tracked_ops: Vec> = Vec::new(); for line in dem_str.lines() { let line = line.trim(); @@ -491,6 +614,42 @@ impl FromStr for ParsedDem { { max_obs = max_obs.max(id as i32); } + Self::record_metadata( + &mut dem_outputs, + DemOutput::new(id) + .with_kind(crate::fault_tolerance::DemOutputKind::Observable), + ); + } + // Parse PECOS DEM-superset metadata declarations. + else if line.starts_with("pecos_observable") + || line.starts_with("pecos_tracked_op") + { + let op = parse_pecos_dem_metadata_line(line) + .map_err(|err| DemParseError::InvalidPecosMetadata(err.to_string()))?; + if op.is_tracked_operator() { + Self::record_metadata(&mut tracked_ops, op); + } else { + #[allow(clippy::cast_possible_wrap)] // observable ID fits in i32 + { + max_obs = max_obs.max(op.id as i32); + } + Self::record_metadata(&mut dem_outputs, op); + } + } + // PECOS extensions are explicit; ordinary Stim lines remain valid, + // but unknown PECOS extension statements should not be silently + // accepted as historical aliases. + else if line.starts_with("pecos_") { + return Err(DemParseError::InvalidPecosMetadata(format!( + "unsupported PECOS DEM extension line: {line}" + ))); + } + } + + if max_obs >= 0 { + #[allow(clippy::cast_sign_loss)] // guarded by >= 0 check + { + dem_outputs.resize(max_obs as usize + 1, None); } } @@ -504,7 +663,7 @@ impl FromStr for ParsedDem { } else { 0 }, - num_observables: if max_obs >= 0 { + num_dem_outputs: if max_obs >= 0 { #[allow(clippy::cast_sign_loss)] // guarded by >= 0 check { max_obs as u32 + 1 @@ -512,6 +671,8 @@ impl FromStr for ParsedDem { } else { 0 }, + dem_outputs, + tracked_ops, }) } } @@ -531,6 +692,8 @@ pub enum DemParseError { InvalidDetectorId(String), /// Invalid observable ID. InvalidObservableId(String), + /// Invalid PECOS DEM-superset metadata. + InvalidPecosMetadata(String), } impl std::fmt::Display for DemParseError { @@ -540,6 +703,7 @@ impl std::fmt::Display for DemParseError { Self::InvalidProbability(s) => write!(f, "Invalid probability: {s}"), Self::InvalidDetectorId(s) => write!(f, "Invalid detector ID: {s}"), Self::InvalidObservableId(s) => write!(f, "Invalid observable ID: {s}"), + Self::InvalidPecosMetadata(s) => write!(f, "Invalid PECOS DEM metadata: {s}"), } } } @@ -713,7 +877,7 @@ pub fn compare_dems_statistical( // Compute detector firing rates (marginals) let num_det = dem1.num_detectors.max(dem2.num_detectors) as usize; - let num_obs = dem1.num_observables.max(dem2.num_observables) as usize; + let num_obs = dem1.num_dem_outputs.max(dem2.num_dem_outputs) as usize; let mut det_rates1 = vec![0.0; num_det]; let mut det_rates2 = vec![0.0; num_det]; @@ -1002,6 +1166,41 @@ mod tests { assert_eq!(dem.mechanisms[0].components[0].observables, vec![0]); } + #[test] + fn test_parse_accepts_pecos_dem_superset_metadata() { + let dem_str = r#" + error(0.02) D0 + pecos_tracked_op {"id":0,"kind":"tracked_operator","label":"track","pauli":"+X0 Z2","records":[]} + "#; + let dem = ParsedDem::from_str(dem_str).unwrap(); + + assert_eq!(dem.mechanisms.len(), 1); + assert_eq!(dem.num_detectors, 1); + assert_eq!(dem.num_dem_outputs(), 0); + assert_eq!(dem.num_observables(), 0); + assert_eq!(dem.num_tracked_ops(), 1); + let op = dem.tracked_ops[0].as_ref().unwrap(); + assert_eq!(op.label.as_deref(), Some("track")); + assert_eq!( + op.kind, + Some(crate::fault_tolerance::DemOutputKind::TrackedOperator) + ); + assert_eq!(op.pauli.as_ref().unwrap().to_sparse_str(), "+X0 Z2"); + } + + #[test] + fn test_parse_rejects_malformed_pecos_dem_superset_metadata() { + let err = ParsedDem::from_str("pecos_tracked_op not-json").unwrap_err(); + assert!(matches!(err, DemParseError::InvalidPecosMetadata(_))); + } + + #[test] + fn test_parse_rejects_unknown_pecos_dem_extension() { + let err = ParsedDem::from_str("pecos_old_extension {}").unwrap_err(); + assert!(matches!(err, DemParseError::InvalidPecosMetadata(_))); + assert!(err.to_string().contains("unsupported PECOS DEM extension")); + } + #[test] fn test_aggregate() { let dem_str = r" diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/mem_builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/mem_builder.rs deleted file mode 100644 index 61892da51..000000000 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/mem_builder.rs +++ /dev/null @@ -1,462 +0,0 @@ -// Copyright 2026 The PECOS Developers -// -// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except -// in compliance with the License. You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software distributed under the License -// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express -// or implied. See the License for the specific language governing permissions and limitations under -// the License. - -//! Measurement Noise Model (MNM) builder implementation. -//! -//! This module builds a MNM from a fault influence map. Unlike the DEM builder -//! which maps to detector effects, the MNM maps directly to measurement effects -//! for fast approximate sampling. -//! -//! # Usage -//! -//! ``` -//! use pecos_qec::fault_tolerance::DagFaultAnalyzer; -//! use pecos_qec::fault_tolerance::dem_builder::MemBuilder; -//! use pecos_quantum::DagCircuit; -//! use rand::SeedableRng; -//! use rand::rngs::SmallRng; -//! -//! let mut dag = DagCircuit::new(); -//! dag.pz(&[2]); -//! dag.cx(&[(0, 2)]); -//! dag.cx(&[(1, 2)]); -//! dag.mz(&[2]); -//! -//! let analyzer = DagFaultAnalyzer::new(&dag); -//! let influence_map = analyzer.build_influence_map(); -//! -//! let mnm = MemBuilder::new(&influence_map) -//! .with_noise(0.01, 0.01, 0.01, 0.01) -//! .build(); -//! -//! // Sample measurement outcomes -//! let mut rng = SmallRng::seed_from_u64(42); -//! let outcomes = mnm.sample(&mut rng); -//! ``` - -use super::types::{MeasurementMechanism, MeasurementNoiseModel, NoiseConfig}; -use crate::fault_tolerance::propagator::{DagFaultInfluenceMap, Pauli}; -use pecos_core::gate_type::GateType; -use smallvec::SmallVec; - -/// Builder for Measurement Noise Models (MNMs). -/// -/// Constructs a MNM from a fault influence map. The MNM aggregates fault locations -/// by their measurement effects (which measurements flip), enabling fast approximate -/// sampling. -/// -/// # Comparison with DEM -/// -/// | Aspect | DEM | MNM | -/// |--------|-----|-----| -/// | Maps to | Detectors | Measurements | -/// | Use case | Decoding | Sampling | -/// | Aggregates by | Detector signature | Measurement signature | -/// | Output | Stim-compatible DEM | Raw measurement outcomes | -pub struct MemBuilder<'a> { - /// Reference to the fault influence map. - influence_map: &'a DagFaultInfluenceMap, - /// Noise configuration. - noise: NoiseConfig, - /// Measurement order from the original circuit (e.g., `TickCircuit`). - /// This is a list of qubits in the order they were measured. - /// `measurement_order[tc_idx] = qubit` means the tc_idx-th measurement - /// in the `TickCircuit` was on this qubit. - measurement_order: Option>, -} - -impl<'a> MemBuilder<'a> { - /// Creates a new MNM builder from a fault influence map. - #[must_use] - pub fn new(influence_map: &'a DagFaultInfluenceMap) -> Self { - Self { - influence_map, - noise: NoiseConfig::default(), - measurement_order: None, - } - } - - /// Sets the noise configuration. - #[must_use] - pub fn with_noise(mut self, p1: f64, p2: f64, p_meas: f64, p_init: f64) -> Self { - self.noise = NoiseConfig::new(p1, p2, p_meas, p_init); - self - } - - /// Sets the measurement order from the original circuit (e.g., `TickCircuit`). - /// - /// This is needed when detector definitions use `TickCircuit` measurement indices - /// but the influence map uses a different ordering based on DAG topology. - /// - /// # Arguments - /// - /// * `order` - List of qubit indices in measurement execution order. - /// `order[tc_idx] = qubit` means the tc_idx-th measurement in the `TickCircuit` - /// was on this qubit. - #[must_use] - pub fn with_measurement_order(mut self, order: Vec) -> Self { - self.measurement_order = Some(order); - self - } - - /// Computes the mapping from influence map measurement indices to `TickCircuit` indices. - /// - /// Returns a vector where `result[im_idx] = tc_idx`, mapping each influence map - /// measurement to its corresponding `TickCircuit` measurement. - fn compute_im_to_tc_mapping(&self, tc_order: &[usize]) -> Vec { - let im_measurements = &self.influence_map.measurements; - let num_measurements = im_measurements.len(); - - // Build map: qubit -> list of TC indices where that qubit is measured - let mut tc_indices_by_qubit: std::collections::BTreeMap> = - std::collections::BTreeMap::new(); - for (tc_idx, &qubit) in tc_order.iter().enumerate() { - tc_indices_by_qubit.entry(qubit).or_default().push(tc_idx); - } - - // Build map: qubit -> list of IM indices where that qubit is measured - let mut im_indices_by_qubit: std::collections::BTreeMap> = - std::collections::BTreeMap::new(); - for (im_idx, &(_node, qubit, _basis)) in im_measurements.iter().enumerate() { - im_indices_by_qubit.entry(qubit).or_default().push(im_idx); - } - - // Build the mapping: for each qubit, match IM indices to TC indices in order - let mut im_to_tc = vec![0; num_measurements]; - for (qubit, im_indices) in &im_indices_by_qubit { - if let Some(tc_indices) = tc_indices_by_qubit.get(qubit) { - // Match in order - the i-th IM measurement of this qubit maps to - // the i-th TC measurement of this qubit - for (i, &im_idx) in im_indices.iter().enumerate() { - if i < tc_indices.len() { - im_to_tc[im_idx] = tc_indices[i]; - } - } - } - } - - im_to_tc - } - - /// Builds the Measurement Noise Model. - /// - /// This aggregates all fault locations by their measurement effects. - /// Locations that produce the same measurement signature have their - /// probabilities combined using the independent error formula. - #[must_use] - pub fn build(&self) -> MeasurementNoiseModel { - let num_measurements = self.influence_map.measurements.len(); - let mut mem = MeasurementNoiseModel::new(num_measurements); - - // Compute im_to_tc mapping if measurement order is provided - if let Some(ref tc_order) = self.measurement_order { - let im_to_tc = self.compute_im_to_tc_mapping(tc_order); - mem.set_measurement_order(im_to_tc); - } - - let locations = &self.influence_map.locations; - - // Group CX locations by node for two-qubit gate processing - let mut cx_groups: std::collections::BTreeMap> = - std::collections::BTreeMap::new(); - - for (loc_idx, loc) in locations.iter().enumerate() { - match loc.gate_type { - GateType::PZ | GateType::QAlloc => { - // Prep errors: only "after" locations - if self.noise.p_init > 0.0 && !loc.before { - self.process_prep_fault(loc_idx, &mut mem); - } - } - GateType::MZ | GateType::MeasureFree => { - // Measurement errors: only "before" locations - if self.noise.p_meas > 0.0 && loc.before { - self.process_meas_fault(loc_idx, &mut mem); - } - } - GateType::CX | GateType::CZ => { - // Two-qubit gate errors: only "after" locations - if !loc.before { - cx_groups.entry(loc.node).or_default().push(loc_idx); - } - } - GateType::H - | GateType::SZ - | GateType::SZdg - | GateType::SX - | GateType::SXdg - | GateType::SY - | GateType::SYdg - | GateType::X - | GateType::Y - | GateType::Z => { - // Single-qubit gate errors: only "after" locations - if self.noise.p1 > 0.0 && !loc.before { - self.process_single_qubit_fault(loc_idx, &mut mem); - } - } - _ => {} - } - } - - // Process two-qubit gates - if self.noise.p2 > 0.0 { - for (_, loc_indices) in cx_groups { - if loc_indices.len() == 2 { - self.process_two_qubit_fault(loc_indices[0], loc_indices[1], &mut mem); - } - } - } - - mem - } - - /// Processes a prep/initialization fault location. - fn process_prep_fault(&self, loc_idx: usize, mem: &mut MeasurementNoiseModel) { - // For Z-basis prep, X error matters - let mechanism = self.compute_mechanism(loc_idx, Pauli::X); - if !mechanism.is_empty() { - mem.add_mechanism(mechanism, self.noise.p_init); - } - } - - /// Processes a measurement fault location. - fn process_meas_fault(&self, loc_idx: usize, mem: &mut MeasurementNoiseModel) { - // Measurement error is a bit flip (X error) - let mechanism = self.compute_mechanism(loc_idx, Pauli::X); - if !mechanism.is_empty() { - mem.add_mechanism(mechanism, self.noise.p_meas); - } - } - - /// Processes a single-qubit gate fault location. - fn process_single_qubit_fault(&self, loc_idx: usize, mem: &mut MeasurementNoiseModel) { - // Depolarizing: each of X, Y, Z with probability p1/3 - let prob = self.noise.p1 / 3.0; - - for pauli in [Pauli::X, Pauli::Y, Pauli::Z] { - let mechanism = self.compute_mechanism(loc_idx, pauli); - if !mechanism.is_empty() { - mem.add_mechanism(mechanism, prob); - } - } - } - - /// Processes a two-qubit gate fault (CX or CZ). - fn process_two_qubit_fault(&self, loc1: usize, loc2: usize, mem: &mut MeasurementNoiseModel) { - // Two-qubit depolarizing: 15 non-identity Pauli combinations with p2/15 each - let prob = self.noise.p2 / 15.0; - - let paulis = [Pauli::I, Pauli::X, Pauli::Y, Pauli::Z]; - - // Cache single-qubit effects for each Pauli on each qubit - let mut effects1: [Option; 4] = [None, None, None, None]; - let mut effects2: [Option; 4] = [None, None, None, None]; - - for &p in &[Pauli::X, Pauli::Y, Pauli::Z] { - effects1[p.as_u8() as usize] = Some(self.compute_mechanism(loc1, p)); - effects2[p.as_u8() as usize] = Some(self.compute_mechanism(loc2, p)); - } - - // Process all 15 non-trivial Pauli combinations - for &p1 in &paulis { - for &p2 in &paulis { - if p1 == Pauli::I && p2 == Pauli::I { - continue; // Skip II - } - - let mechanism = if p1 == Pauli::I { - // IX, IY, IZ - effects2[p2.as_u8() as usize].clone().unwrap_or_default() - } else if p2 == Pauli::I { - // XI, YI, ZI - effects1[p1.as_u8() as usize].clone().unwrap_or_default() - } else { - // Correlated: XOR the measurement effects - let e1 = effects1[p1.as_u8() as usize].as_ref(); - let e2 = effects2[p2.as_u8() as usize].as_ref(); - xor_measurement_mechanisms(e1, e2) - }; - - if !mechanism.is_empty() { - mem.add_mechanism(mechanism, prob); - } - } - } - } - - /// Computes the measurement mechanism for a fault at the given location and Pauli type. - fn compute_mechanism(&self, loc_idx: usize, pauli: Pauli) -> MeasurementMechanism { - // Get the measurement indices that this fault flips - let measurements = self - .influence_map - .get_detector_indices(loc_idx, pauli.as_u8()); - - let mut meas_vec: SmallVec<[u32; 4]> = measurements.iter().copied().collect(); - meas_vec.sort_unstable(); - - MeasurementMechanism::from_sorted(meas_vec) - } -} - -/// XORs two measurement mechanisms (symmetric difference). -fn xor_measurement_mechanisms( - a: Option<&MeasurementMechanism>, - b: Option<&MeasurementMechanism>, -) -> MeasurementMechanism { - match (a, b) { - (Some(m1), Some(m2)) => { - let mut result: SmallVec<[u32; 4]> = SmallVec::new(); - let mut i = 0; - let mut j = 0; - - while i < m1.measurements.len() && j < m2.measurements.len() { - match m1.measurements[i].cmp(&m2.measurements[j]) { - std::cmp::Ordering::Less => { - result.push(m1.measurements[i]); - i += 1; - } - std::cmp::Ordering::Greater => { - result.push(m2.measurements[j]); - j += 1; - } - std::cmp::Ordering::Equal => { - // Same element in both - XOR cancels - i += 1; - j += 1; - } - } - } - - result.extend_from_slice(&m1.measurements[i..]); - result.extend_from_slice(&m2.measurements[j..]); - - MeasurementMechanism::from_sorted(result) - } - (Some(m), None) | (None, Some(m)) => m.clone(), - (None, None) => MeasurementMechanism::new(), - } -} - -#[cfg(test)] -mod tests { - use super::*; - use crate::fault_tolerance::propagator::DagFaultAnalyzer; - use pecos_quantum::DagCircuit; - - #[test] - fn test_mem_builder_simple() { - // Simple circuit: prep, cx, measure - let mut dag = DagCircuit::new(); - dag.pz(&[2]); // Prep ancilla - dag.cx(&[(0, 2)]); // CNOT data -> ancilla - dag.cx(&[(1, 2)]); // CNOT data -> ancilla - dag.mz(&[2]); // Measure ancilla - - let analyzer = DagFaultAnalyzer::new(&dag); - let influence_map = analyzer.build_influence_map(); - - let mem = MemBuilder::new(&influence_map) - .with_noise(0.01, 0.01, 0.01, 0.01) - .build(); - - // Should have some mechanisms - assert!(mem.num_mechanisms() > 0); - assert_eq!(mem.num_measurements, 1); - } - - #[test] - fn test_mem_builder_aggregation() { - // Circuit where multiple locations produce the same measurement effect - let mut dag = DagCircuit::new(); - dag.pz(&[2]); - dag.cx(&[(0, 2)]); - dag.cx(&[(1, 2)]); - dag.mz(&[2]); - - let analyzer = DagFaultAnalyzer::new(&dag); - let influence_map = analyzer.build_influence_map(); - - let mem = MemBuilder::new(&influence_map) - .with_noise(0.01, 0.01, 0.01, 0.01) - .build(); - - // Count how many mechanisms flip measurement 0 - let single_meas_mechanisms: Vec<_> = mem - .iter() - .filter(|(m, _)| m.measurements.as_slice() == [0]) - .collect(); - - // Should have aggregated multiple sources into one mechanism - // (prep X error + measurement X error both flip measurement 0) - assert!( - single_meas_mechanisms.len() == 1, - "Expected aggregation of mechanisms with same effect" - ); - - // Combined probability should be > individual probability - let combined_prob = single_meas_mechanisms[0].1; - assert!( - *combined_prob > 0.01, - "Combined probability should be greater than single source" - ); - } - - #[test] - fn test_mem_sampling() { - use rand::SeedableRng; - use rand::rngs::SmallRng; - - let mut dag = DagCircuit::new(); - dag.pz(&[2]); - dag.cx(&[(0, 2)]); - dag.mz(&[2]); - - let analyzer = DagFaultAnalyzer::new(&dag); - let influence_map = analyzer.build_influence_map(); - - let mem = MemBuilder::new(&influence_map) - .with_noise(0.1, 0.1, 0.1, 0.1) // High error rate for testing - .build(); - - let mut rng = SmallRng::seed_from_u64(42); - - // Sample many shots and count flips - let num_shots = 10000; - let mut flip_count = 0; - - for _ in 0..num_shots { - let outcomes = mem.sample(&mut rng); - if outcomes.first().copied().unwrap_or(false) { - flip_count += 1; - } - } - - // Should have some flips (not 0) and some non-flips (not all) - assert!(flip_count > 0, "Should have some measurement flips"); - assert!( - flip_count < num_shots, - "Should not have all measurements flipped" - ); - } - - #[test] - fn test_xor_measurement_mechanisms() { - let m1 = MeasurementMechanism::from_unsorted([0, 1, 2]); - let m2 = MeasurementMechanism::from_unsorted([1, 2, 3]); - - let result = xor_measurement_mechanisms(Some(&m1), Some(&m2)); - - // {0, 1, 2} XOR {1, 2, 3} = {0, 3} - assert_eq!(result.measurements.as_slice(), &[0, 3]); - } -} diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs new file mode 100644 index 000000000..180ac230a --- /dev/null +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs @@ -0,0 +1,1742 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Unified sampler for noisy QEC measurement outcomes. +//! +//! This sampler unifies the DEM (detector-level) and MNM (measurement-level) +//! sampling paths into a single type. Internally it uses [`DemSampler`]'s +//! efficient geometric-skip engine for fault mechanism sampling, then applies +//! an optional detector basis change and non-deterministic coin flips depending +//! on the requested output mode. +//! +//! # Coordinate systems +//! +//! Deterministic measurements form a basis in `Z_2`. User-defined detectors are +//! linear combinations (XOR chains) of these measurements — a change of basis. +//! The sampler always builds its mechanism table in raw measurement coordinates, +//! then applies the basis change at build time if detector definitions are +//! provided. +//! +//! # Construction modes +//! +//! - **Raw measurements**: each deterministic measurement is its own "detector." +//! Output includes coin flips for non-deterministic measurements. +//! - **Auto-detected detectors**: uses the influence builder's detector +//! definitions (round-to-round XOR of stabilizer measurements). +//! - **User-defined detectors**: arbitrary XOR combinations of measurements, +//! validated at build time. + +use super::dem_sampler::SamplingEngine; +use super::types::{DemOutput, NoiseConfig}; +use crate::fault_tolerance::propagator::{DagFaultInfluenceMap, DemOutputKind}; +use pecos_core::prelude::GateType; +use pecos_num::z2_linalg::z2_rank_from_records; +use pecos_random::RngProbabilityExt; +use rand_core::Rng; + +/// Errors from detector definition validation. +#[derive(Debug, Clone)] +pub enum DetectorValidationError { + /// A detector definition references a non-deterministic measurement. + NonDeterministicReference { + detector_id: usize, + measurement_idx: usize, + }, + /// Detector definitions are not linearly independent over `Z_2`. + LinearlyDependent { rank: usize, num_detectors: usize }, + /// Circuit contains gates not supported by the symbolic determinism analysis. + /// Raw measurement mode requires all gates to be in the supported Clifford + /// subset (H, X, Y, Z, SZ, SZdg, CX, CZ, SWAP, MZ, PZ, I). + UnsupportedGateForDeterminismAnalysis { gate_type: String }, +} + +impl std::fmt::Display for DetectorValidationError { + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + match self { + Self::NonDeterministicReference { + detector_id, + measurement_idx, + } => { + write!( + f, + "Detector {detector_id} references non-deterministic measurement {measurement_idx}. \ + Detectors should only XOR deterministic measurements." + ) + } + Self::LinearlyDependent { + rank, + num_detectors, + } => { + write!( + f, + "Detector definitions are not linearly independent: \ + rank {rank} < {num_detectors} detectors. \ + Some detectors are redundant (XOR of other detectors)." + ) + } + Self::UnsupportedGateForDeterminismAnalysis { gate_type } => { + write!( + f, + "Circuit contains gate type '{gate_type}' which is not supported by \ + raw measurement determinism analysis. Supported Clifford gates: \ + H, X, Y, Z, SZ, SZdg, CX, CZ, SWAP, MZ, PZ/QAlloc, I/Idle." + ) + } + } + } +} + +impl std::error::Error for DetectorValidationError {} + +/// Output mode for the unified sampler. +#[derive(Debug, Clone, Copy, PartialEq, Eq)] +pub enum OutputMode { + /// Output raw measurement values (deterministic flips + non-det coin flips). + RawMeasurements, + /// Output detector events (XOR of measurement groups) + observable flips. + DetectorEvents, +} + +/// Unified sampler that handles both measurement-level and detector-level output. +/// +/// Uses [`DemSampler`]'s geometric-skip engine internally. The mechanism table +/// is always in the output coordinate system (raw measurements or user detectors), +/// determined at build time. +/// Result of dual-mode sampling: both raw measurements and detector events. +#[derive(Debug, Clone)] +pub struct DualSampleResult { + /// Raw measurement values (deterministic flips + non-det coin flips). + pub raw_measurements: Vec, + /// Detector events (XOR of measurement groups). + pub detector_events: Vec, + /// Standard DEM `L` observable output flips. + pub dem_output_flips: Vec, +} + +/// Labels for sampler output channels. +#[derive(Debug, Clone, Default)] +pub struct SamplerLabels { + /// Labels for output channels (raw measurements or detectors, depending on mode). + pub outputs: Vec>, + /// Labels for standard DEM `L` observable outputs. + /// Indices match `per_dem_output` in `SamplingStatistics`. + pub dem_output_labels: Vec>, + /// Full PECOS metadata for standard DEM `L` observables. + pub dem_outputs: Vec>, + /// Labels for PECOS tracked operators. + pub tracked_op_labels: Vec>, + /// Full PECOS metadata for tracked operators in their own ID space. + pub tracked_ops: Vec>, + /// Labels for dual-output detector channels. + pub dual_detectors: Vec>, +} + +fn dem_outputs_by_id(targets: &[DemOutput], num_dem_outputs: usize) -> Vec> { + let mut by_id = vec![None; num_dem_outputs]; + for target in targets { + let idx = target.id as usize; + if idx < by_id.len() { + by_id[idx] = Some(target.clone()); + } + } + by_id +} + +fn labels_from_dem_outputs(targets: &[Option]) -> Vec> { + targets + .iter() + .map(|target| target.as_ref().and_then(|target| target.label.clone())) + .collect() +} + +fn dem_outputs_from_influence_map( + influence_map: &DagFaultInfluenceMap, + num_dem_outputs: usize, +) -> Vec> { + let mut targets = vec![None; num_dem_outputs]; + for (internal_id, metadata) in influence_map.dem_output_metadata.iter().enumerate() { + if metadata.kind == DemOutputKind::Observable { + #[allow(clippy::cast_possible_truncation)] // DEM output count fits in u32 + if let Some(dem_output_id) = + influence_map.observable_id_for_internal_dem_output(internal_id as u32) + { + let idx = dem_output_id as usize; + if idx < targets.len() { + targets[idx] = Some(DemOutput::from_metadata(dem_output_id, metadata)); + } + } + } + } + targets +} + +fn tracked_ops_from_influence_map(influence_map: &DagFaultInfluenceMap) -> Vec> { + let mut tracked_ops = Vec::new(); + for metadata in &influence_map.dem_output_metadata { + if metadata.kind == DemOutputKind::TrackedOperator { + #[allow(clippy::cast_possible_truncation)] // tracked-op count fits in u32 + let id = tracked_ops.len() as u32; + tracked_ops.push(Some(DemOutput::from_metadata(id, metadata))); + } + } + tracked_ops +} + +fn dem_outputs_from_records( + influence_map: &DagFaultInfluenceMap, + observable_records: &[Vec], + num_dem_outputs: usize, +) -> Vec> { + let mut targets = dem_outputs_from_influence_map(influence_map, num_dem_outputs); + + for (record_id, records) in observable_records.iter().enumerate() { + let dem_output_id = record_id; + if dem_output_id < targets.len() { + #[allow(clippy::cast_possible_truncation)] // DEM output count fits in u32 + { + targets[dem_output_id] = Some( + DemOutput::new(dem_output_id as u32).with_records(records.iter().copied()), + ); + } + } + } + + targets +} + +fn merge_dem_output_metadata( + mut labels: SamplerLabels, + targets: Vec>, + tracked_ops: Vec>, +) -> SamplerLabels { + if labels.dem_outputs.len() < targets.len() { + labels.dem_outputs.resize(targets.len(), None); + } + for (idx, target) in targets.into_iter().enumerate() { + if labels.dem_outputs[idx].is_none() { + labels.dem_outputs[idx] = target; + } + } + + let target_labels = labels_from_dem_outputs(&labels.dem_outputs); + if labels.dem_output_labels.len() < target_labels.len() { + labels.dem_output_labels.resize(target_labels.len(), None); + } + for (idx, label) in target_labels.into_iter().enumerate() { + if labels.dem_output_labels[idx].is_none() { + labels.dem_output_labels[idx] = label; + } + } + + if labels.tracked_ops.len() < tracked_ops.len() { + labels.tracked_ops.resize(tracked_ops.len(), None); + } + for (idx, tracked_op) in tracked_ops.into_iter().enumerate() { + if labels.tracked_ops[idx].is_none() { + labels.tracked_ops[idx] = tracked_op; + } + } + + let tracked_op_labels = labels_from_dem_outputs(&labels.tracked_ops); + if labels.tracked_op_labels.len() < tracked_op_labels.len() { + labels.tracked_op_labels.resize(tracked_op_labels.len(), None); + } + for (idx, label) in tracked_op_labels.into_iter().enumerate() { + if labels.tracked_op_labels[idx].is_none() { + labels.tracked_op_labels[idx] = label; + } + } + + labels +} + +#[derive(Debug, Clone)] +pub struct DemSampler { + /// The efficient sampling engine (mechanism table in raw measurement coords). + inner: SamplingEngine, + + /// Which output indices are non-deterministic (true = coin flip, not from mechanisms). + /// Length = num_outputs (full measurement space in raw mode). + non_det_mask: Vec, + + /// Deterministic measurement dependencies for raw mode. + /// `measurement_deps[i] = Some((deps, flip))` means measurement i is determined by + /// XOR(measurements[j] for j in deps) XOR flip. None = non-det (coin flip) or fault-only. + /// Used to propagate non-det coin flips through the dependency chain. + measurement_deps: Vec, bool)>>, + + /// Detector definitions for dual-output mode. + /// Each entry is a list of absolute measurement indices to XOR. + detector_records_abs: Vec>, + + /// Output mode this sampler was built for. + mode: OutputMode, + + /// Total number of output channels (measurements or detectors). + num_outputs: usize, + + /// Total number of outputs in the DEM `L` namespace. + num_dem_outputs: usize, + + /// Optional labels for output channels. + labels: SamplerLabels, + + /// Remap table for raw mode: engine index → absolute measurement index. + /// When set, the engine operates in compressed coordinates (only fault-reachable + /// measurements) and the output is expanded to the full measurement space. + /// None when engine coordinates == output coordinates (no expansion needed). + raw_remap: Option>, +} + +impl DemSampler { + /// Build a `DemSampler` directly from an annotated circuit and noise config. + /// + /// This is the simplest way to go from circuit to sampler. It: + /// 1. Builds a raw-measurement influence map via `DagFaultAnalyzer` + /// 2. Extracts detector, observable, and Pauli check annotations from the circuit + /// 3. Applies the noise configuration + /// 4. Returns a ready-to-sample `DemSampler` + /// + /// For circuits with Pauli check annotations, this also builds + /// the influence map with those checks via `InfluenceBuilder`. + /// + /// # Errors + /// + /// Returns [`DetectorValidationError`] if any detector references a + /// non-deterministic measurement or the detectors are linearly dependent. + /// + /// # Example + /// + /// ```ignore + /// let mut dag = DagCircuit::new(); + /// // ... build circuit, add detectors/observables ... + /// let sampler = DemSampler::from_circuit(&dag, NoiseConfig::uniform(0.01))?; + /// let (det, obs) = sampler.sample(&mut rng); + /// ``` + /// Build a sampler from a `TickCircuit` and noise parameters. + /// + /// Converts to `DagCircuit` internally. Returns detector-mode sampler. + pub fn from_tick_circuit( + circuit: &pecos_quantum::TickCircuit, + noise: super::types::NoiseConfig, + ) -> Result { + let dag = pecos_quantum::DagCircuit::from(circuit); + Self::from_circuit(&dag, noise) + } + + /// Build a sampler from a `DagCircuit` and noise parameters. + pub fn from_circuit( + circuit: &pecos_quantum::DagCircuit, + noise: super::types::NoiseConfig, + ) -> Result { + // Build the DetectorErrorModel via DemBuilder (single code path for + // DEM computation), then convert to sampler. + use super::builder::DemBuilder; + use crate::fault_tolerance::influence_builder::InfluenceBuilder; + use crate::fault_tolerance::propagator::DagFaultAnalyzer; + + let mut influence_map = DagFaultAnalyzer::new(circuit).build_influence_map(); + let annotation_map = InfluenceBuilder::new(circuit) + .with_circuit_annotations(circuit) + .build(); + influence_map.merge_dem_outputs_from(&annotation_map); + + // Extract metadata before building (avoids ownership issues with builder methods) + let det_json = { + use pecos_num::graph::Attribute; + circuit.get_attr("detectors").and_then(|a| { + if let Attribute::String(s) = a { + Some(s.clone()) + } else { + None + } + }) + }; + let observables_json = { + use pecos_num::graph::Attribute; + circuit + .get_attr("observables") + .and_then(|a| { + if let Attribute::String(s) = a { + Some(s.clone()) + } else { + None + } + }) + }; + let num_meas = { + use pecos_num::graph::Attribute; + circuit.get_attr("num_measurements").and_then(|a| { + if let Attribute::String(s) = a { + s.parse::().ok() + } else { + None + } + }) + }; + + // Build DemBuilder, applying detector/DEM-output JSON if available. + // with_detectors_json/with_observables_json consume self, so we + // chain them carefully. + let builder = DemBuilder::new(&influence_map).with_noise_config(noise.clone()); + + let builder = if let Some(ref dj) = det_json { + builder.with_detectors_json(dj).unwrap_or_else(|_| { + DemBuilder::new(&influence_map).with_noise_config(noise.clone()) + }) + } else { + builder + }; + + let builder = if let Some(ref oj) = observables_json { + builder.with_observables_json(oj).unwrap_or_else(|_| { + DemBuilder::new(&influence_map).with_noise_config(noise.clone()) + }) + } else { + builder + }; + + let builder = if let Some(n) = num_meas { + builder.with_num_measurements(n) + } else { + builder + }; + + let dem = builder.build(); + Ok(Self::from_detector_error_model(&dem)) + } + + /// Wrap a raw [`SamplingEngine`] as a detector-mode `DemSampler`. + /// + /// Used when the engine was constructed externally (e.g., from + /// [`ParsedDem::to_dem_sampler`]). + #[must_use] + /// Create a `DemSampler` from a pre-built `SamplingEngine`. + pub fn from_engine(engine: SamplingEngine) -> Self { + let num_outputs = engine.num_detectors(); + let num_dem_outputs = engine.num_dem_outputs(); + Self { + inner: engine, + non_det_mask: Vec::new(), + detector_records_abs: Vec::new(), + mode: OutputMode::DetectorEvents, + num_outputs, + num_dem_outputs, + labels: SamplerLabels::default(), + raw_remap: None, + measurement_deps: Vec::new(), + } + } + + /// Build a detector-event sampler from a [`DetectorErrorModel`], preserving + /// PECOS metadata for observables and tracked operators. + #[must_use] + pub fn from_detector_error_model(dem: &super::types::DetectorErrorModel) -> Self { + let (mechanisms, _coords) = dem.to_mechanisms(); + let engine = + SamplingEngine::from_mechanisms(mechanisms, dem.num_detectors(), dem.num_dem_outputs()); + let mut sampler = Self::from_engine(engine); + sampler.labels.dem_outputs = dem_outputs_by_id(dem.dem_outputs(), dem.num_dem_outputs()); + sampler.labels.dem_output_labels = labels_from_dem_outputs(&sampler.labels.dem_outputs); + sampler.labels.tracked_ops = dem_outputs_by_id(dem.tracked_ops(), dem.num_tracked_ops()); + sampler.labels.tracked_op_labels = labels_from_dem_outputs(&sampler.labels.tracked_ops); + sampler + } + + /// Create a `DemSampler` directly from an influence map with per-location + /// probabilities (raw measurement mode). + #[must_use] + pub fn from_influence_map( + influence_map: &DagFaultInfluenceMap, + per_location_probs: &[f64], + ) -> Self { + let default_noise = super::NoiseConfig::default(); + let inner = + SamplingEngine::from_influence_map(influence_map, per_location_probs, &default_noise); + let num_outputs = inner.num_detectors(); + let num_dem_outputs = inner.num_dem_outputs(); + let mut labels = SamplerLabels::default(); + labels.dem_outputs = dem_outputs_from_influence_map(influence_map, num_dem_outputs); + labels.dem_output_labels = labels_from_dem_outputs(&labels.dem_outputs); + labels.tracked_ops = tracked_ops_from_influence_map(influence_map); + labels.tracked_op_labels = labels_from_dem_outputs(&labels.tracked_ops); + Self { + inner, + non_det_mask: Vec::new(), + detector_records_abs: Vec::new(), + mode: OutputMode::RawMeasurements, + num_outputs, + num_dem_outputs, + labels, + raw_remap: None, + measurement_deps: Vec::new(), + } + } + + /// Number of output channels (measurements in raw mode, detectors in detector mode). + #[must_use] + pub fn num_outputs(&self) -> usize { + self.num_outputs + } + + /// Number of detectors (alias for [`num_outputs`] in detector mode). + #[must_use] + pub fn num_detectors(&self) -> usize { + self.num_outputs + } + + /// Number of observables. + #[must_use] + pub fn num_observables(&self) -> usize { + self.num_dem_outputs + } + + /// Number of DEM `L` output channels. + #[must_use] + pub fn num_dem_outputs(&self) -> usize { + self.num_dem_outputs + } + + /// Number of tracked operators. + #[must_use] + pub fn num_tracked_ops(&self) -> usize { + self.labels.tracked_ops.iter().flatten().count() + } + + /// DEM output indices classified as observables. + #[must_use] + pub fn observable_dem_output_indices(&self) -> Vec { + (0..self.num_dem_outputs).collect() + } + + /// DEM output indices classified as tracked operators. + #[must_use] + pub fn tracked_operator_dem_output_indices(&self) -> Vec { + Vec::new() + } + + /// Bit mask selecting observable outputs. + /// + /// Existing decoder APIs use `u64` observable masks, so outputs with index + /// >= 64 are not representable here and are ignored consistently with the + /// existing mask-based paths. + #[must_use] + pub fn observable_dem_output_mask(&self) -> u64 { + self.observable_dem_output_indices() + .into_iter() + .filter(|&idx| idx < u64::BITS as usize) + .fold(0u64, |acc, idx| acc | (1u64 << idx)) + } + + /// Converts a sampled DEM-output flip vector into an observable-only mask. + #[must_use] + pub fn observable_mask_from_dem_output_flips(&self, flips: &[bool]) -> u64 { + let observable_mask = self.observable_dem_output_mask(); + flips + .iter() + .enumerate() + .filter(|(idx, flipped)| { + **flipped && *idx < u64::BITS as usize && (observable_mask & (1u64 << *idx)) != 0 + }) + .fold(0u64, |acc, (idx, _)| acc | (1u64 << idx)) + } + + /// Number of mechanisms in the sampler. + #[must_use] + pub fn num_mechanisms(&self) -> usize { + self.inner.num_mechanisms() + } + + /// Get the labels for this sampler's output channels. + #[must_use] + pub fn labels(&self) -> &SamplerLabels { + &self.labels + } + + /// Output mode this sampler was built for. + #[must_use] + pub fn mode(&self) -> OutputMode { + self.mode + } + + /// Finalize raw measurement outputs: expand coordinates, apply non-det coin + /// flips, and propagate deterministic dependencies. + /// + /// This is the single post-processing path for all raw-mode sampling methods. + fn finalize_raw_output(&self, engine_outputs: Vec, rng: &mut R) -> Vec { + // Step 1: Expand engine output to full measurement space if remapping + let mut outputs = if let Some(ref remap) = self.raw_remap { + let mut full = vec![false; self.num_outputs]; + for (engine_idx, &abs_idx) in remap.iter().enumerate() { + if engine_idx < engine_outputs.len() && abs_idx < full.len() { + full[abs_idx] = engine_outputs[engine_idx]; + } + } + full + } else { + engine_outputs + }; + + // Step 2: Add coin flips for non-deterministic measurements + for (i, &is_non_det) in self.non_det_mask.iter().enumerate() { + if is_non_det && i < outputs.len() { + outputs[i] ^= rng.coin_flip(); + } + } + + // Step 3: Propagate deterministic measurement dependencies. + // For m_i with deps {j, k, ...}: m_i XOR= XOR(m_j, m_k, ...) XOR flip + // Dependencies are always to earlier measurements (processed in order). + for i in 0..outputs.len().min(self.measurement_deps.len()) { + if let Some((ref deps, flip)) = self.measurement_deps[i] { + let dep_xor = deps + .iter() + .filter(|&&j| j < outputs.len()) + .fold(flip, |acc, &j| acc ^ outputs[j]); + outputs[i] ^= dep_xor; + } + } + + outputs + } + + /// Sample a single shot. + /// + /// Returns `(outputs, dem_output_flips)` where outputs are either raw + /// measurement values or detector events depending on the mode. + #[must_use] + pub fn sample(&self, rng: &mut R) -> (Vec, Vec) { + let (engine_outputs, dem_outputs) = self.inner.sample(rng); + + let outputs = if self.mode == OutputMode::RawMeasurements { + self.finalize_raw_output(engine_outputs, rng) + } else { + engine_outputs + }; + + (outputs, dem_outputs) + } + + /// Sample multiple shots. + #[must_use] + pub fn sample_batch( + &self, + num_shots: usize, + rng: &mut R, + ) -> (Vec>, Vec>) { + let (engine_batches, all_dem_outputs) = self.inner.sample_batch(num_shots, rng); + + let all_outputs: Vec> = if self.mode == OutputMode::RawMeasurements { + engine_batches + .into_iter() + .map(|engine_out| self.finalize_raw_output(engine_out, rng)) + .collect() + } else { + engine_batches + }; + + (all_outputs, all_dem_outputs) + } + + /// Batch sample using geometric skip — O(fired) instead of O(all mechanisms). + /// + /// Returns columnar bit-packed data: + /// - detector columns: `[num_detectors][ceil(num_shots/64)]` u64 words + /// - `L` target columns: `[num_dem_outputs][ceil(num_shots/64)]` u64 words + /// + /// Much faster than `sample_batch` at low error rates where few mechanisms fire. + /// Only available in detector-event mode (not raw measurement mode). + /// + /// # Panics + /// + /// Panics if the sampler is in raw measurement mode. + #[must_use] + pub fn sample_batch_geometric( + &self, + num_shots: usize, + rng: &mut R, + ) -> (Vec>, Vec>) { + assert!( + self.mode != OutputMode::RawMeasurements, + "sample_batch_geometric() does not support raw measurement mode \ + (requires non-det coin flips + dependency propagation per shot). \ + Use sample_batch() instead." + ); + self.inner.sample_batch_columnar_geometric(num_shots, rng) + } + + /// Sample a single shot and return both raw measurements and detector events. + /// + /// This uses a single RNG sequence to produce both outputs consistently. + /// Requires the sampler to have been built in raw measurement mode with + /// detector definitions stored via the builder. + /// + /// Returns `None` if no detector definitions are available. + #[must_use] + pub fn sample_dual(&self, rng: &mut R) -> Option { + if self.detector_records_abs.is_empty() { + return None; + } + + // Sample mechanism flips in raw measurement coordinates + let (raw_flips, dem_output_flips) = self.inner.sample(rng); + + // Finalize raw measurements (expand, coin flips, dependency propagation) + let raw_measurements = self.finalize_raw_output(raw_flips, rng); + + // Compute detector events from FINALIZED raw measurements + // (includes non-det coin flips and dependency propagation) + let detector_events: Vec = self + .detector_records_abs + .iter() + .map(|record| { + record.iter().fold(false, |acc, &idx| { + acc ^ raw_measurements.get(idx).copied().unwrap_or(false) + }) + }) + .collect(); + + Some(DualSampleResult { + raw_measurements, + detector_events, + dem_output_flips, + }) + } + + /// Compute statistics with a user-provided RNG. + #[must_use] + pub fn sample_statistics_with_rng( + &self, + num_shots: usize, + rng: &mut R, + ) -> super::dem_sampler::SamplingStatistics { + let observable_indices = self.observable_dem_output_indices(); + self.inner + .sample_statistics_with_rng_for_observable_indices(num_shots, rng, &observable_indices) + } + + /// Compute statistics without storing individual shots. + /// + /// Delegates to [`DemSampler::sample_statistics`] which auto-selects + /// the fastest algorithm. Non-deterministic coin flips do NOT affect + /// statistics since they are independent of faults and cancel in + /// expectation for any well-formed detector. + #[must_use] + pub fn sample_statistics( + &self, + num_shots: usize, + seed: u64, + ) -> super::dem_sampler::SamplingStatistics { + let observable_indices = self.observable_dem_output_indices(); + self.inner + .sample_statistics_for_observable_indices(num_shots, seed, &observable_indices) + } +} + +// ============================================================================ +// Builder +// ============================================================================ + +/// Builder for [`DemSampler`]. +/// +/// Constructs a sampler from a fault influence map and noise parameters. +/// The output mode (raw measurements vs detector events) is determined by +/// how the builder is configured. +pub struct DemSamplerBuilder<'a> { + influence_map: &'a DagFaultInfluenceMap, + noise: NoiseConfig, + output_mode: OutputMode, + detector_records: Option>>, + observable_records: Option>>, + measurement_order: Option>, + detector_records_abs: Option>>, + labels: SamplerLabels, +} + +impl<'a> DemSamplerBuilder<'a> { + /// Create a new builder. Default mode is raw measurements. + #[must_use] + pub fn new(influence_map: &'a DagFaultInfluenceMap) -> Self { + Self { + influence_map, + noise: NoiseConfig::default(), + output_mode: OutputMode::RawMeasurements, + detector_records: None, + observable_records: None, + measurement_order: None, + detector_records_abs: None, + labels: SamplerLabels::default(), + } + } + + /// Set noise parameters. + #[must_use] + pub fn with_noise(mut self, p1: f64, p2: f64, p_meas: f64, p_prep: f64) -> Self { + self.noise = NoiseConfig::new(p1, p2, p_meas, p_prep); + self + } + + /// Set noise from a `NoiseConfig` (includes `p_idle` if set). + #[must_use] + pub fn with_noise_config(mut self, config: NoiseConfig) -> Self { + self.noise = config; + self + } + + /// Set uniform noise (same probability for all gate types, including idle). + #[must_use] + pub fn with_uniform_noise(self, p: f64) -> Self { + let mut s = self.with_noise(p, p, p, p); + s.noise.p_idle = p; + s + } + + /// Set idle gate noise rate. + #[must_use] + pub fn with_idle_noise(mut self, p_idle: f64) -> Self { + self.noise.p_idle = p_idle; + self + } + + /// Request raw measurement output (default). + /// + /// Each deterministic measurement is its own output channel. Non-deterministic + /// measurements get independent coin flips. + #[must_use] + pub fn raw_measurements(mut self) -> Self { + self.output_mode = OutputMode::RawMeasurements; + self.detector_records = None; + self.observable_records = None; + self + } + + /// Request detector-event output with the given detector/DEM output definitions. + /// + /// Detector records use Stim-style negative offsets: `[-1]` means "the last + /// measurement", `[-3, -1]` means "XOR of the last and third-to-last." + #[must_use] + pub fn with_detectors( + mut self, + detector_records: Vec>, + observable_records: Vec>, + ) -> Self { + self.output_mode = OutputMode::DetectorEvents; + self.detector_records = Some(detector_records); + self.observable_records = Some(observable_records); + self + } + + /// Set detector records directly (without observables). + #[must_use] + pub fn with_detector_records(mut self, records: Vec>) -> Self { + self.output_mode = OutputMode::DetectorEvents; + self.detector_records = Some(records); + if self.observable_records.is_none() { + self.observable_records = Some(Vec::new()); + } + self + } + + /// Set observable definitions directly. + #[must_use] + pub fn with_observable_records(mut self, records: Vec>) -> Self { + self.observable_records = Some(records); + self + } + + /// Set detector definitions from JSON. + /// + /// Format: `[{"id": 0, "records": [-1, -5]}, ...]` + /// + /// # Errors + /// Returns an error if the JSON is malformed. + pub fn with_detectors_json(self, json: &str) -> Result { + let records = parse_records_json(json); + Ok(self.with_detector_records(records)) + } + + /// Set observable definitions from JSON. + /// + /// Format: `[{"id": 0, "records": [-1, -3, -5]}, ...]` + /// + /// # Errors + /// Returns an error if the JSON is malformed. + pub fn with_observables_json(self, json: &str) -> Result { + let records = parse_records_json(json); + Ok(self.with_observable_records(records)) + } + + /// Enable dual output (raw measurements + detector events from same sample). + /// + /// When building in raw measurement mode, stores the detector definitions + /// so that [`DemSampler::sample_dual`] can compute both outputs. + /// The records use absolute measurement indices (not negative offsets). + #[must_use] + pub fn with_dual_output(mut self, detector_records_abs: Vec>) -> Self { + self.detector_records_abs = Some(detector_records_abs); + self + } + + /// Extract detector, observable, and tracked-op definitions from a [`DagCircuit`]'s + /// in-circuit annotations. + /// + /// Extract annotations from a [`DagCircuit`] and configure the sampler. + /// + /// Detector annotations are mapped to auto-detected detector indices. + /// Observables are converted to measurement-record outputs. Operators are + /// tracked through PECOS metadata only. + #[must_use] + pub fn with_circuit_annotations(mut self, circuit: &pecos_quantum::DagCircuit) -> Self { + use pecos_quantum::AnnotationKind; + + let mut node_to_meas_idx: std::collections::BTreeMap = + std::collections::BTreeMap::new(); + for (meas_idx, &(node, _qubit, _basis)) in + self.influence_map.measurements.iter().enumerate() + { + node_to_meas_idx.entry(node).or_insert(meas_idx); + } + + let detectors: Vec<&pecos_quantum::PauliAnnotation> = circuit.detectors().collect(); + let observables: Vec<&pecos_quantum::PauliAnnotation> = circuit.observables().collect(); + + // Map user-defined detector annotations to auto-detected detector indices + if !detectors.is_empty() { + // For each IM measurement index, find which auto-detector contains it + let mut meas_idx_to_auto_det: Vec> = + vec![None; self.influence_map.measurements.len()]; + for (det_idx, det) in self.influence_map.detectors.iter().enumerate() { + for meas_id in &det.measurements { + for (im_idx, &(_node, qubit, basis)) in + self.influence_map.measurements.iter().enumerate() + { + if qubit == meas_id.qubit + && basis == meas_id.basis + && meas_idx_to_auto_det[im_idx].is_none() + { + meas_idx_to_auto_det[im_idx] = Some(det_idx); + break; + } + } + } + } + + // Map each user detector: measurement_nodes → IM meas index → auto-detector index + let det_records_abs: Vec> = detectors + .iter() + .map(|ann| { + if let AnnotationKind::Detector { + measurement_nodes, .. + } = &ann.kind + { + measurement_nodes + .iter() + .filter_map(|&node| { + let im_idx = node_to_meas_idx.get(&node)?; + meas_idx_to_auto_det[*im_idx] + }) + .collect() + } else { + Vec::new() + } + }) + .collect(); + + self.labels.dual_detectors = detectors.iter().map(|a| a.label.clone()).collect(); + self.detector_records_abs = Some(det_records_abs); + } + + if !observables.is_empty() && self.observable_records.is_none() { + #[allow(clippy::cast_possible_truncation, clippy::cast_possible_wrap)] + let num_measurements = self.influence_map.measurements.len() as i32; + let records = observables + .iter() + .map(|ann| { + if let AnnotationKind::Observable { measurement_nodes } = &ann.kind { + measurement_nodes + .iter() + .filter_map(|node| node_to_meas_idx.get(node).copied()) + .map(|meas_idx| meas_idx as i32 - num_measurements) + .collect() + } else { + Vec::new() + } + }) + .collect(); + self.observable_records = Some(records); + } + + let observable_labels: Vec> = + observables.iter().map(|a| a.label.clone()).collect(); + if !observable_labels.is_empty() { + self.labels.dem_output_labels = observable_labels; + } + + let tracked_op_labels: Vec> = circuit + .annotations() + .iter() + .filter(|a| matches!(a.kind, AnnotationKind::Operator)) + .map(|a| a.label.clone()) + .collect(); + if !tracked_op_labels.is_empty() { + self.labels.tracked_op_labels = tracked_op_labels; + } + + self + } + + /// Set the measurement order for legacy circuits without `MeasId` on gates. + /// + /// **Not needed for circuits built with `TickCircuit.mz()`** — the `MeasId` + /// values on gates ensure correct ordering automatically. + #[must_use] + pub fn with_measurement_order(mut self, order: Vec) -> Self { + self.measurement_order = Some(order); + self + } + + /// Build the sampler. + /// + /// # Errors + /// + /// Returns an error if detector definitions reference non-deterministic + /// measurements or are not linearly independent over `Z_2`. + pub fn build(self) -> Result { + match self.output_mode { + OutputMode::RawMeasurements => Ok(self.build_raw()), + OutputMode::DetectorEvents => self.build_detector(), + } + } + + /// Build in raw measurement mode. + /// + /// Mechanism table is in measurement coordinates. Non-deterministic + /// measurements are identified and marked for coin-flip output. + fn build_raw(self) -> DemSampler { + let num_measurements = self.influence_map.measurements.len(); + + // Build per-location probabilities from gate-type noise + let per_location_probs = self.compute_per_location_probs(); + + // Build mechanism table in raw measurement coordinates + let inner = SamplingEngine::from_influence_map( + self.influence_map, + &per_location_probs, + &self.noise, + ); + + // Identify non-deterministic measurements. + // A measurement is deterministic if the influence builder found it + // as part of a detector definition. If it's NOT in any detector, + // it might be non-deterministic (first-round stabilizer, data readout). + // + // Conservative approach: mark a measurement as non-deterministic if + // it doesn't appear in any detector definition. This isn't perfect + // (some deterministic measurements might not be in detectors) but + // is safe — extra coin flips on deterministic measurements that + // happen to not be in detectors just add noise. + let mut in_detector = vec![false; num_measurements]; + for det in &self.influence_map.detectors { + for m in &det.measurements { + // Find measurement index by matching qubit + tick + for (idx, &(_node, qubit, _basis)) in + self.influence_map.measurements.iter().enumerate() + { + if qubit == m.qubit { + in_detector[idx] = true; + } + } + } + } + let non_det_mask: Vec = in_detector.iter().map(|&in_det| !in_det).collect(); + + let num_dem_outputs = inner.num_dem_outputs(); + let dem_outputs = dem_outputs_from_influence_map(self.influence_map, num_dem_outputs); + let tracked_ops = tracked_ops_from_influence_map(self.influence_map); + + DemSampler { + inner, + non_det_mask, + detector_records_abs: self.detector_records_abs.unwrap_or_default(), + mode: OutputMode::RawMeasurements, + num_outputs: num_measurements, + num_dem_outputs, + labels: merge_dem_output_metadata(self.labels, dem_outputs, tracked_ops), + raw_remap: None, + measurement_deps: Vec::new(), // No expansion needed (engine covers all measurements) + } + } + + /// Build in detector-event mode. + /// + /// Validates detector definitions, then uses `DemSamplerBuilder` to build + /// the mechanism table in detector coordinates. + fn build_detector(self) -> Result { + use super::dem_sampler::SamplingEngineBuilder; + + let num_measurements = self.influence_map.measurements.len(); + + // Validate: check which measurements are deterministic (before partial move) + let deterministic = self.compute_deterministic_mask(); + + let detector_records = self.detector_records.unwrap_or_default(); + let observable_records = self.observable_records.unwrap_or_default(); + let num_detectors = detector_records.len(); + + // Check that all detector records reference deterministic measurements + for (det_id, records) in detector_records.iter().enumerate() { + for &offset in records { + // Resolve offset to an absolute index: negative offsets count + // backward from the end of the measurement list. + #[allow(clippy::cast_sign_loss)] // offset is non-negative in else branch + let abs_idx = if offset < 0 { + let neg = offset.unsigned_abs() as usize; + if neg > num_measurements { + continue; + } + num_measurements - neg + } else { + offset as usize + }; + + if abs_idx < num_measurements && !deterministic[abs_idx] { + return Err(DetectorValidationError::NonDeterministicReference { + detector_id: det_id, + measurement_idx: abs_idx, + }); + } + } + } + + // Check linear independence via Gaussian elimination over Z_2 + if num_detectors > 0 { + let rank = z2_rank_from_records(&detector_records, num_measurements); + if rank < num_detectors { + return Err(DetectorValidationError::LinearlyDependent { + rank, + num_detectors, + }); + } + } + + let mut builder = SamplingEngineBuilder::new(self.influence_map) + .with_noise( + self.noise.p1, + self.noise.p2, + self.noise.p_meas, + self.noise.p_prep, + ) + .with_detector_records(detector_records) + .with_observable_records(observable_records.clone()); + + if let Some(order) = self.measurement_order { + builder = builder.with_measurement_order(order); + } + + let inner = builder.build(); + let num_dem_outputs = inner.num_dem_outputs(); + let dem_outputs = + dem_outputs_from_records(self.influence_map, &observable_records, num_dem_outputs); + let tracked_ops = tracked_ops_from_influence_map(self.influence_map); + + Ok(DemSampler { + inner, + non_det_mask: Vec::new(), + detector_records_abs: Vec::new(), + mode: OutputMode::DetectorEvents, + num_outputs: num_detectors, + num_dem_outputs, + labels: merge_dem_output_metadata(self.labels, dem_outputs, tracked_ops), + raw_remap: None, + measurement_deps: Vec::new(), + }) + } + + /// Compute which measurements are deterministic. + /// + /// A measurement is considered deterministic if it appears in at least + /// one detector definition in the influence map. + fn compute_deterministic_mask(&self) -> Vec { + let num_measurements = self.influence_map.measurements.len(); + let mut deterministic = vec![false; num_measurements]; + + for det in &self.influence_map.detectors { + for m in &det.measurements { + for (idx, &(_node, qubit, _basis)) in + self.influence_map.measurements.iter().enumerate() + { + if qubit == m.qubit { + deterministic[idx] = true; + } + } + } + } + + deterministic + } + + /// Compute per-location error probabilities from gate-type noise config. + /// + /// Returns the total error probability per location. For T1/T2 idle noise, + /// this is the sum of the biased Pauli probabilities. + fn compute_per_location_probs(&self) -> Vec { + compute_location_probs_from_noise(&self.influence_map.locations, &self.noise) + } +} + +/// Compute per-location total error probabilities from noise config. +/// +/// For T1/T2 idle noise, returns the sum of biased Pauli probabilities. +/// For all other gates, returns the gate-type probability. +pub(crate) fn compute_location_probs_from_noise( + locations: &[super::super::propagator::dag::DagSpacetimeLocation], + noise: &NoiseConfig, +) -> Vec { + locations + .iter() + .map(|loc| { + #[allow(clippy::match_same_arms)] + match loc.gate_type { + GateType::PZ | GateType::QAlloc => noise.p_prep, + GateType::MZ | GateType::MeasureFree => noise.p_meas, + GateType::CX + | GateType::CZ + | GateType::CY + | GateType::SZZ + | GateType::SZZdg + | GateType::SXX + | GateType::SXXdg + | GateType::SYY + | GateType::SYYdg + | GateType::SWAP + | GateType::RXX + | GateType::RYY + | GateType::RZZ => noise.p2, + GateType::Idle => { + // Duration values are small integers; precision loss is not a concern. + #[allow(clippy::cast_precision_loss)] + let duration = loc.idle_duration.max(1) as f64; + noise.idle_pauli_probs(duration).total() + } + _ => noise.p1, + } + }) + .collect() +} + +/// Get the per-qubit error probability for a gate fault location. +pub(crate) fn gate_location_prob_from_locations( + loc: &super::super::propagator::dag::GateFaultLocation<'_>, + loc_probs: &[f64], + all_locations: &[super::super::propagator::dag::DagSpacetimeLocation], +) -> f64 { + for (i, l) in all_locations.iter().enumerate() { + if l.node == loc.node && l.before == loc.before { + return loc_probs[i]; + } + } + 0.0 +} + +/// Parse detector or observable definitions from JSON. +/// +/// Run noiseless symbolic simulation on a TickCircuit to identify non-deterministic measurements. +/// +/// Returns a Vec where true = non-deterministic (needs coin flip). +/// Uses SymbolicSparseStab which tracks measurement determinism symbolically. +/// Run noiseless symbolic simulation to identify non-deterministic measurements +/// and their dependency structure. +/// +/// Returns: +/// - `Vec`: non-det mask (true = needs coin flip) +/// - `Vec, bool)>>`: per-measurement dependencies +/// (Some((deps, flip)) for deterministic measurements, None for non-det) +/// +/// Only supports the Clifford gate subset. Returns error for unsupported gates. +fn parse_records_json(json: &str) -> Vec> { + let json = json.trim(); + if json.is_empty() || json == "[]" { + return Vec::new(); + } + + let mut results = Vec::new(); + let mut depth = 0; + let mut start = None; + + for (i, c) in json.char_indices() { + match c { + '{' => { + if depth == 1 { + start = Some(i); + } + depth += 1; + } + '}' => { + depth -= 1; + if depth == 1 { + if let Some(s) = start { + let obj_str = &json[s..i + c.len_utf8()]; + results.push(extract_records_array(obj_str)); + } + start = None; + } + } + '[' if depth == 0 => depth = 1, + ']' if depth == 1 => depth = 0, + _ => {} + } + } + + results +} + +/// Extract measurement record indices from a JSON object string. +/// +/// Prefers `"meas_ids"` (absolute MeasId IDs) when available. +/// Falls back to `"records"` (negative offsets) for legacy compatibility. +fn extract_records_array(json: &str) -> Vec { + // Prefer meas_ids (absolute, stable IDs from MeasId) + if let Some(pos) = json.find("\"meas_ids\"") { + let rest = &json[pos..]; + if let (Some(arr_start), Some(arr_end)) = (rest.find('['), rest.find(']')) + && arr_start < arr_end + { + let arr_str = &rest[arr_start + 1..arr_end]; + let ids: Vec = arr_str + .split(',') + .filter_map(|s| s.trim().parse::().ok()) + .collect(); + if !ids.is_empty() { + // Convert absolute MeasId IDs to negative offsets: + // not needed — the DemBuilder resolves negative offsets against + // num_measurements. With absolute IDs, we store them as positive + // values and handle them in the DemBuilder's build_measurement_mappings. + // + // For now, keep the negative-offset convention internally but + // convert: absolute ID i becomes offset -(num_measurements - i). + // We don't know num_measurements here, so return the absolute IDs + // as positive i32. The DemBuilder recognizes positive values as + // absolute MeasId indices. + return ids; + } + } + } + + // Fallback: "records" with negative offsets + if let Some(pos) = json.find("\"records\"") { + let rest = &json[pos..]; + if let (Some(arr_start), Some(arr_end)) = (rest.find('['), rest.find(']')) + && arr_start < arr_end + { + let arr_str = &rest[arr_start + 1..arr_end]; + return arr_str + .split(',') + .filter_map(|s| s.trim().parse::().ok()) + .collect(); + } + } + Vec::new() +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::fault_tolerance::InfluenceBuilder; + use pecos_quantum::DagCircuit; + use pecos_random::PecosRng; + + fn repetition_code(rounds: usize) -> DagCircuit { + let mut dag = DagCircuit::new(); + for _ in 0..rounds { + dag.pz(&[3]); + dag.pz(&[4]); + dag.cx(&[(0, 3)]); + dag.cx(&[(1, 3)]); + dag.cx(&[(1, 4)]); + dag.cx(&[(2, 4)]); + dag.mz(&[3]); + dag.mz(&[4]); + } + dag + } + + #[test] + fn raw_mode_output_length_matches_measurements() { + let circuit = repetition_code(2); + let im = InfluenceBuilder::new(&circuit).with_z(&[0, 1, 2]).build(); + + let sampler = DemSamplerBuilder::new(&im) + .with_uniform_noise(0.01) + .raw_measurements() + .build() + .unwrap(); + + let mut rng = PecosRng::seed_from_u64(42); + let (outputs, _obs) = sampler.sample(&mut rng); + + assert_eq!(outputs.len(), im.measurements.len()); + assert_eq!(sampler.mode(), OutputMode::RawMeasurements); + } + + #[test] + fn zero_noise_raw_mode_deterministic_measurements_are_zero() { + let circuit = repetition_code(3); + let im = InfluenceBuilder::new(&circuit).with_z(&[0, 1, 2]).build(); + + let sampler = DemSamplerBuilder::new(&im) + .with_uniform_noise(0.0) + .raw_measurements() + .build() + .unwrap(); + + // With zero noise, deterministic measurement flips should all be false. + // Non-deterministic ones get coin flips so we can't assert on those. + // But the mechanism-driven part should be all-zero. + let stats = sampler.sample_statistics(1000, 42); + assert_eq!(stats.syndrome_count, 0); + assert_eq!(stats.logical_error_count, 0); + } + + #[test] + fn raw_mode_matches_dem_sampler_from_influence_map() { + let circuit = repetition_code(3); + let im = InfluenceBuilder::new(&circuit).with_z(&[0, 1, 2]).build(); + + let p = 0.01; + let num_shots = 20_000; + + // DemSampler raw mode + let sampler = DemSamplerBuilder::new(&im) + .with_uniform_noise(p) + .raw_measurements() + .build() + .unwrap(); + + let unified_stats = sampler.sample_statistics(num_shots, 42); + + // DemSampler::from_influence_map (same mechanism construction) + let probs = vec![p; im.locations.len()]; + let dem = DemSampler::from_influence_map(&im, &probs); + let dem_stats = dem.sample_statistics(num_shots, 42); + + // Same seed, same mechanism construction → identical results + assert_eq!(unified_stats.syndrome_count, dem_stats.syndrome_count); + assert_eq!( + unified_stats.logical_error_count, + dem_stats.logical_error_count + ); + } + + #[test] + fn detector_mode_output_length_matches_definitions() { + let circuit = repetition_code(3); + let im = InfluenceBuilder::new(&circuit).build(); + + // Define 2 simple detectors (last two measurements) + let detector_records = vec![vec![-1i32], vec![-2]]; + let observable_records = vec![vec![-1i32]]; // 1 observable + + let sampler = DemSamplerBuilder::new(&im) + .with_noise(0.001, 0.01, 0.005, 0.001) + .with_detectors(detector_records, observable_records) + .build() + .unwrap(); + + let mut rng = PecosRng::seed_from_u64(42); + let (det_events, obs_flips) = sampler.sample(&mut rng); + + assert_eq!(det_events.len(), 2); + assert_eq!(obs_flips.len(), 1); + assert_eq!(sampler.mode(), OutputMode::DetectorEvents); + } + + #[test] + fn detector_mode_accepts_observable_aliases() { + let circuit = repetition_code(3); + let im = InfluenceBuilder::new(&circuit).build(); + + let records_sampler = DemSamplerBuilder::new(&im) + .with_detector_records(vec![vec![-1]]) + .with_observable_records(vec![vec![-1]]) + .build() + .unwrap(); + + assert_eq!(records_sampler.num_detectors(), 1); + assert_eq!(records_sampler.num_dem_outputs(), 1); + assert_eq!(records_sampler.num_observables(), 1); + assert_eq!(records_sampler.num_tracked_ops(), 0); + assert_eq!(records_sampler.mode(), OutputMode::DetectorEvents); + + let json_sampler = DemSamplerBuilder::new(&im) + .with_detectors_json(r#"[{"id":0,"records":[-1]}]"#) + .unwrap() + .with_observables_json(r#"[{"id":0,"records":[-1]}]"#) + .unwrap() + .build() + .unwrap(); + + assert_eq!(json_sampler.num_detectors(), 1); + assert_eq!(json_sampler.num_dem_outputs(), 1); + assert_eq!(json_sampler.num_observables(), 1); + assert_eq!(json_sampler.num_tracked_ops(), 0); + assert_eq!(json_sampler.mode(), OutputMode::DetectorEvents); + } + + #[test] + fn from_circuit_preserves_pauli_operator_tracked_ops() { + use crate::fault_tolerance::dem_builder::NoiseConfig; + use pecos_core::pauli::constructors::X; + + let mut circuit = DagCircuit::new(); + circuit.pz(&[0]); + circuit.h(&[0]); + circuit.pauli_operator_labeled("x_check", X(0)); + + let sampler = + DemSampler::from_circuit(&circuit, NoiseConfig::new(0.03, 0.0, 0.0, 0.0)).unwrap(); + + assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!(sampler.num_observables(), 0); + assert_eq!( + sampler.labels().tracked_op_labels[0].as_deref(), + Some("x_check") + ); + let op = sampler.labels().tracked_ops[0].as_ref().unwrap(); + assert_eq!(op.label.as_deref(), Some("x_check")); + assert_eq!( + op.kind, + Some(crate::fault_tolerance::DemOutputKind::TrackedOperator) + ); + assert_eq!(op.pauli.as_ref().unwrap().to_sparse_str(), "+X0"); + } + + #[test] + fn detector_mode_keeps_observables_unshifted_with_pauli_operators() { + use pecos_core::pauli::constructors::X; + + let mut circuit = DagCircuit::new(); + circuit.pz(&[0]); + circuit.h(&[0]); + circuit.pauli_operator_labeled("x_check", X(0)); + circuit.mz(&[0]); + + let im = InfluenceBuilder::new(&circuit) + .with_circuit_annotations(&circuit) + .build(); + + let sampler = DemSamplerBuilder::new(&im) + .with_noise(0.03, 0.0, 0.02, 0.0) + .with_detectors(Vec::new(), vec![vec![-1]]) + .build() + .unwrap(); + + assert_eq!(sampler.num_dem_outputs(), 1); + assert_eq!(sampler.num_observables(), 1); + assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!(sampler.labels().dem_outputs.len(), 1); + assert_eq!( + sampler.labels().dem_outputs[0].as_ref().unwrap().kind, + Some(crate::fault_tolerance::DemOutputKind::Observable) + ); + assert_eq!( + sampler.labels().tracked_ops[0].as_ref().unwrap().kind, + Some(crate::fault_tolerance::DemOutputKind::TrackedOperator) + ); + } + + #[test] + fn from_detector_error_model_preserves_observable_and_tracked_operator_split() { + use super::super::builder::DemBuilder; + use pecos_core::pauli::constructors::X; + use pecos_quantum::Attribute; + + let mut circuit = DagCircuit::new(); + circuit.pz(&[0]); + circuit.h(&[0]); + circuit.pauli_operator_labeled("x_check", X(0)); + circuit.mz(&[0]); + circuit.set_attr("num_measurements", Attribute::String("1".to_string())); + circuit.set_attr( + "observables", + Attribute::String(r#"[{"id":0,"records":[-1]}]"#.to_string()), + ); + + let dem = DemBuilder::from_circuit(&circuit, 0.03, 0.0, 0.02, 0.0); + + let sampler = DemSampler::from_detector_error_model(&dem); + + assert_eq!(sampler.num_dem_outputs(), 1); + assert_eq!(sampler.num_observables(), 1); + assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!( + sampler.labels().dem_outputs[0].as_ref().unwrap().kind, + Some(crate::fault_tolerance::DemOutputKind::Observable) + ); + assert_eq!( + sampler.labels().tracked_ops[0].as_ref().unwrap().kind, + Some(crate::fault_tolerance::DemOutputKind::TrackedOperator) + ); + } + + #[test] + fn raw_mode_without_dem_outputs_reports_zero_dem_outputs() { + let mut circuit = DagCircuit::new(); + circuit.pz(&[0]); + circuit.h(&[0]); + circuit.mz(&[0]); + let im = InfluenceBuilder::new(&circuit).build(); + + let sampler = DemSamplerBuilder::new(&im) + .with_uniform_noise(0.01) + .raw_measurements() + .build() + .unwrap(); + + assert_eq!(sampler.num_dem_outputs(), 0); + assert_eq!(sampler.num_observables(), 0); + assert_eq!(sampler.num_tracked_ops(), 0); + } + + #[test] + fn observable_mask_ignores_tracked_operator_outputs() { + use super::super::builder::DemBuilder; + use pecos_core::pauli::constructors::X; + use pecos_quantum::Attribute; + + let mut circuit = DagCircuit::new(); + circuit.pz(&[0]); + circuit.h(&[0]); + circuit.pauli_operator_labeled("x_check", X(0)); + circuit.mz(&[0]); + circuit.set_attr("num_measurements", Attribute::String("1".to_string())); + circuit.set_attr( + "observables", + Attribute::String(r#"[{"id":0,"records":[-1]}]"#.to_string()), + ); + + let dem = DemBuilder::from_circuit(&circuit, 0.03, 0.0, 0.02, 0.0); + let sampler = DemSampler::from_detector_error_model(&dem); + + assert_eq!(sampler.observable_dem_output_indices(), vec![0]); + assert_eq!(sampler.tracked_operator_dem_output_indices(), Vec::::new()); + assert_eq!(sampler.observable_dem_output_mask(), 1); + assert_eq!( + sampler.observable_mask_from_dem_output_flips(&[false]), + 0 + ); + assert_eq!( + sampler.observable_mask_from_dem_output_flips(&[true]), + 1 + ); + } + + #[test] + fn high_noise_produces_nonzero_rates_both_modes() { + let circuit = repetition_code(2); + let im = InfluenceBuilder::new(&circuit).with_z(&[0, 1, 2]).build(); + + let p = 0.1; + let num_shots = 5_000; + + // Raw mode + let raw_sampler = DemSamplerBuilder::new(&im) + .with_uniform_noise(p) + .raw_measurements() + .build() + .unwrap(); + let raw_stats = raw_sampler.sample_statistics(num_shots, 42); + assert!( + raw_stats.syndrome_rate() > 0.05, + "Raw mode should detect syndromes at p=0.1" + ); + + // Detector mode with simple detectors + let detector_records = vec![vec![-1i32], vec![-2]]; + let observable_records: Vec> = vec![]; + let det_sampler = DemSamplerBuilder::new(&im) + .with_uniform_noise(p) + .with_detectors(detector_records, observable_records) + .build() + .unwrap(); + let det_stats = det_sampler.sample_statistics(num_shots, 42); + assert!( + det_stats.syndrome_rate() > 0.05, + "Detector mode should detect syndromes at p=0.1" + ); + } + + #[test] + fn dual_output_returns_none_without_definitions() { + let circuit = repetition_code(2); + let im = InfluenceBuilder::new(&circuit).with_z(&[0, 1, 2]).build(); + + let sampler = DemSamplerBuilder::new(&im) + .with_uniform_noise(0.01) + .raw_measurements() + .build() + .unwrap(); + + let mut rng = PecosRng::seed_from_u64(42); + assert!(sampler.sample_dual(&mut rng).is_none()); + } + + #[test] + fn dual_output_produces_both_views() { + let circuit = repetition_code(3); + let im = InfluenceBuilder::new(&circuit).with_z(&[0, 1, 2]).build(); + + // Define detectors: first and second measurements + let det_defs = vec![vec![0usize], vec![1]]; + + let sampler = DemSamplerBuilder::new(&im) + .with_uniform_noise(0.05) + .raw_measurements() + .with_dual_output(det_defs) + .build() + .unwrap(); + + let mut rng = PecosRng::seed_from_u64(42); + let result = sampler.sample_dual(&mut rng).unwrap(); + + // Raw measurements should have length = num measurements + assert_eq!(result.raw_measurements.len(), im.measurements.len()); + // Detector events should have length = 2 (our 2 detector defs) + assert_eq!(result.detector_events.len(), 2); + } + + #[test] + fn dual_output_detector_events_consistent_with_raw() { + let circuit = repetition_code(3); + let im = InfluenceBuilder::new(&circuit).with_z(&[0, 1, 2]).build(); + + // Detector = XOR of measurements 0 and 1 + let det_defs = vec![vec![0usize, 1]]; + + let sampler = DemSamplerBuilder::new(&im) + .with_uniform_noise(0.1) + .raw_measurements() + .with_dual_output(det_defs) + .build() + .unwrap(); + + // Run many shots and verify detector = raw[0] XOR raw[1] + let mut rng = PecosRng::seed_from_u64(42); + for _ in 0..100 { + let result = sampler.sample_dual(&mut rng).unwrap(); + let expected_det = result.raw_measurements[0] ^ result.raw_measurements[1]; + assert_eq!( + result.detector_events[0], expected_det, + "Detector event should equal XOR of raw measurements 0 and 1" + ); + } + } +} diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs index 398808e49..0fa8ab93f 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs @@ -12,8 +12,15 @@ //! Types for Detector Error Model (DEM) generation. //! -//! This module provides data structures for representing error mechanisms, -//! detectors, and logical observables in DEM format. +//! This module provides data structures for representing fault mechanisms, +//! detectors, observables, and PECOS tracked operators. +//! +//! # Terminology +//! +//! Stim DEM syntax calls `L` entries logical observables. PECOS keeps that +//! namespace reserved for measurement-record observables only. Tracked Pauli +//! operators are PECOS metadata with their own ID space so decoders can ignore +//! them while PECOS tools can still inspect them. //! //! # Output Formats //! @@ -37,13 +44,16 @@ //! This indicates an error decomposed into two parts whose XOR equals the //! original mechanism. -use rand::RngExt; +use pecos_core::PauliString; +use pecos_core::gate_type::GateType; use smallvec::SmallVec; use std::cmp::Ordering; -use std::collections::{BTreeMap, HashMap, HashSet}; +use std::collections::{BTreeMap, BTreeSet}; use std::fmt; use std::hash::{Hash, Hasher}; +use crate::fault_tolerance::propagator::{DemOutputKind, DemOutputMetadata, Pauli}; + // ============================================================================ // Error Source Tracking // ============================================================================ @@ -53,27 +63,63 @@ use std::hash::{Hash, Hasher}; /// This tracks how an error contribution was generated, which determines /// how it should be output in the decomposed DEM format: /// - Direct errors (X, Z channels) -> output as direct form +/// - Direct one-sided component errors -> output as direct form for now, but +/// keep their source family distinct for later decomposition policy work /// - Y-decomposed errors -> output as decomposed form (X ^ Z) -#[derive(Debug, Clone, PartialEq, Eq)] -pub enum ErrorSourceType { +#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)] +pub enum FaultSourceType { /// Direct X or Z error channel - outputs as direct form only. /// These represent single Pauli errors that cannot be further decomposed. Direct, + /// Direct two-location source where exactly one per-location component equals + /// the full effect and the other component is empty. + /// + /// These rows currently render the same as `Direct`, but the subtype is kept + /// so decomposition policy can distinguish them later without reconstructing + /// the family from builder-time component metadata. + DirectOneSidedComponent, + /// Y error decomposed as X^Z - outputs as decomposed form. /// The X and Z component effects are stored for decomposition output. YDecomposed { /// Detector effect of the X component (sorted detector IDs). x_detectors: SmallVec<[u32; 4]>, - /// Logical effect of the X component (sorted logical IDs). - x_logicals: SmallVec<[u32; 2]>, + /// DEM-output effect of the X component (sorted `L` IDs). + x_dem_outputs: SmallVec<[u32; 2]>, /// Detector effect of the Z component (sorted detector IDs). z_detectors: SmallVec<[u32; 4]>, - /// Logical effect of the Z component (sorted logical IDs). - z_logicals: SmallVec<[u32; 2]>, + /// DEM-output effect of the Z component (sorted `L` IDs). + z_dem_outputs: SmallVec<[u32; 2]>, }, } +/// Coarse source-family classification for direct contributions. +/// +/// This is intentionally descriptive instead of prescriptive: it keeps the main +/// direct source families separate for downstream analysis without changing +/// rendered DEM behavior. +#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] +pub enum DirectSourceFamily { + /// Single-location direct source without a Y Pauli label. + SingleLocation, + + /// Single-location direct source with a Y Pauli label. + SingleLocationY, + + /// Two-location direct source routed from a Y-containing channel. + TwoLocationPlainY, + + /// Two-location direct source with recorded per-location components. + TwoLocationComponent, + + /// Two-location direct source where exactly one component is non-empty. + TwoLocationOneSidedComponent, + + /// Fallback for other direct-source shapes. + Other, +} + /// An error contribution with source tracking. /// /// This represents a single error source's contribution to the DEM, @@ -81,25 +127,186 @@ pub enum ErrorSourceType { /// with the same effect are grouped at output time, with their source types /// determining how they are output (direct vs decomposed forms). #[derive(Debug, Clone)] -pub struct ErrorContribution { - /// The detector/logical effect of this error. - pub effect: ErrorMechanism, +pub struct FaultContribution { + /// The detector/DEM-output effect of this error. + pub effect: FaultMechanism, /// Probability of this error. pub probability: f64, /// Source classification for decomposition decisions. - pub source_type: ErrorSourceType, + pub source_type: FaultSourceType, + + /// Fault location indices in the influence map that produced this contribution. + pub location_indices: SmallVec<[u32; 2]>, + + /// Original Pauli channel at each tracked location. + pub paulis: SmallVec<[Pauli; 2]>, + + /// Gate type at each tracked source location. + pub source_gate_types: SmallVec<[GateType; 2]>, + + /// Whether each tracked source location is before (`true`) or after (`false`) its gate. + pub source_before_flags: SmallVec<[bool; 2]>, + + /// Coarse direct-source family for read-only analysis. + pub direct_source_family: Option, + + /// Optional per-location component effects for direct multi-location sources. + /// + /// These are builder-time component effects whose XOR equals `effect`. They are + /// currently recorded for direct two-qubit channel sources to aid decomposition + /// analysis without changing emitted DEM behavior. + pub direct_component_effects: Option<(FaultMechanism, FaultMechanism)>, +} + +#[derive(Debug, Clone, Copy)] +pub(crate) struct SourceMetadata<'a, Index> { + location_indices: &'a [Index], + paulis: &'a [Pauli], + gate_types: &'a [GateType], + before_flags: &'a [bool], +} + +impl<'a, Index> SourceMetadata<'a, Index> { + pub(crate) const fn new( + location_indices: &'a [Index], + paulis: &'a [Pauli], + gate_types: &'a [GateType], + before_flags: &'a [bool], + ) -> Self { + Self { + location_indices, + paulis, + gate_types, + before_flags, + } + } +} + +#[derive(Debug, Clone, Copy)] +pub(crate) struct DirectSourceComponents<'a> { + first: &'a FaultMechanism, + second: &'a FaultMechanism, +} + +impl<'a> DirectSourceComponents<'a> { + pub(crate) const fn new(first: &'a FaultMechanism, second: &'a FaultMechanism) -> Self { + Self { first, second } + } } -impl ErrorContribution { +impl FaultContribution { + fn classify_direct_source_family( + location_indices: &[u32], + paulis: &[Pauli], + direct_component_effects: Option<(&FaultMechanism, &FaultMechanism)>, + ) -> Option { + if location_indices.is_empty() { + return None; + } + + let has_y = paulis.contains(&Pauli::Y); + + match location_indices.len() { + 1 => Some(if has_y { + DirectSourceFamily::SingleLocationY + } else { + DirectSourceFamily::SingleLocation + }), + 2 => { + if let Some((first, second)) = direct_component_effects { + if first.is_empty() ^ second.is_empty() { + Some(DirectSourceFamily::TwoLocationOneSidedComponent) + } else { + Some(DirectSourceFamily::TwoLocationComponent) + } + } else if has_y { + Some(DirectSourceFamily::TwoLocationPlainY) + } else { + Some(DirectSourceFamily::Other) + } + } + _ => Some(DirectSourceFamily::Other), + } + } + /// Creates a new direct error contribution (X or Z channel). #[must_use] - pub fn direct(effect: ErrorMechanism, probability: f64) -> Self { + pub fn direct(effect: FaultMechanism, probability: f64) -> Self { + Self { + effect, + probability, + source_type: FaultSourceType::Direct, + location_indices: SmallVec::new(), + paulis: SmallVec::new(), + source_gate_types: SmallVec::new(), + source_before_flags: SmallVec::new(), + direct_source_family: None, + direct_component_effects: None, + } + } + + /// Creates a new direct error contribution with source metadata. + #[must_use] + fn direct_with_source( + effect: FaultMechanism, + probability: f64, + source: SourceMetadata<'_, u32>, + ) -> Self { + debug_assert_eq!(source.location_indices.len(), source.paulis.len()); + debug_assert_eq!(source.location_indices.len(), source.gate_types.len()); + debug_assert_eq!(source.location_indices.len(), source.before_flags.len()); + Self { + effect, + probability, + source_type: FaultSourceType::Direct, + location_indices: source.location_indices.iter().copied().collect(), + paulis: source.paulis.iter().copied().collect(), + source_gate_types: source.gate_types.iter().copied().collect(), + source_before_flags: source.before_flags.iter().copied().collect(), + direct_source_family: Self::classify_direct_source_family( + source.location_indices, + source.paulis, + None, + ), + direct_component_effects: None, + } + } + + /// Creates a new direct error contribution with source metadata and + /// per-location component effects. + #[must_use] + fn direct_with_source_components( + effect: FaultMechanism, + probability: f64, + source: SourceMetadata<'_, u32>, + components: DirectSourceComponents<'_>, + ) -> Self { + debug_assert_eq!(source.location_indices.len(), source.paulis.len()); + debug_assert_eq!(source.location_indices.len(), source.gate_types.len()); + debug_assert_eq!(source.location_indices.len(), source.before_flags.len()); + let source_type = if (components.first == &effect && components.second.is_empty()) + || (components.second == &effect && components.first.is_empty()) + { + FaultSourceType::DirectOneSidedComponent + } else { + FaultSourceType::Direct + }; Self { effect, probability, - source_type: ErrorSourceType::Direct, + source_type, + location_indices: source.location_indices.iter().copied().collect(), + paulis: source.paulis.iter().copied().collect(), + source_gate_types: source.gate_types.iter().copied().collect(), + source_before_flags: source.before_flags.iter().copied().collect(), + direct_source_family: Self::classify_direct_source_family( + source.location_indices, + source.paulis, + Some((components.first, components.second)), + ), + direct_component_effects: Some((components.first.clone(), components.second.clone())), } } @@ -109,103 +316,244 @@ impl ErrorContribution { /// allowing the decomposed form (X ^ Z) to be output. #[must_use] pub fn y_decomposed( - combined_effect: ErrorMechanism, - x_effect: &ErrorMechanism, - z_effect: &ErrorMechanism, + combined_effect: FaultMechanism, + x_effect: &FaultMechanism, + z_effect: &FaultMechanism, + probability: f64, + ) -> Self { + Self { + effect: combined_effect, + probability, + source_type: FaultSourceType::YDecomposed { + x_detectors: x_effect.detectors.clone(), + x_dem_outputs: x_effect.dem_outputs.clone(), + z_detectors: z_effect.detectors.clone(), + z_dem_outputs: z_effect.dem_outputs.clone(), + }, + location_indices: SmallVec::new(), + paulis: SmallVec::new(), + source_gate_types: SmallVec::new(), + source_before_flags: SmallVec::new(), + direct_source_family: None, + direct_component_effects: None, + } + } + + /// Creates a new Y-decomposed error contribution with source metadata. + #[must_use] + fn y_decomposed_with_source( + combined_effect: FaultMechanism, + x_effect: &FaultMechanism, + z_effect: &FaultMechanism, probability: f64, + source: SourceMetadata<'_, u32>, ) -> Self { + debug_assert_eq!(source.location_indices.len(), source.paulis.len()); + debug_assert_eq!(source.location_indices.len(), source.gate_types.len()); + debug_assert_eq!(source.location_indices.len(), source.before_flags.len()); Self { effect: combined_effect, probability, - source_type: ErrorSourceType::YDecomposed { + source_type: FaultSourceType::YDecomposed { x_detectors: x_effect.detectors.clone(), - x_logicals: x_effect.logicals.clone(), + x_dem_outputs: x_effect.dem_outputs.clone(), z_detectors: z_effect.detectors.clone(), - z_logicals: z_effect.logicals.clone(), + z_dem_outputs: z_effect.dem_outputs.clone(), }, + location_indices: source.location_indices.iter().copied().collect(), + paulis: source.paulis.iter().copied().collect(), + source_gate_types: source.gate_types.iter().copied().collect(), + source_before_flags: source.before_flags.iter().copied().collect(), + direct_source_family: None, + direct_component_effects: None, } } /// Returns true if this is a direct (non-decomposable) source. #[must_use] pub fn is_direct(&self) -> bool { - matches!(self.source_type, ErrorSourceType::Direct) + matches!( + self.source_type, + FaultSourceType::Direct | FaultSourceType::DirectOneSidedComponent + ) } /// Returns the X and Z components if this is a Y-decomposed source. #[must_use] - pub fn decomposition_components(&self) -> Option<(ErrorMechanism, ErrorMechanism)> { + pub fn decomposition_components(&self) -> Option<(FaultMechanism, FaultMechanism)> { match &self.source_type { - ErrorSourceType::YDecomposed { + FaultSourceType::YDecomposed { x_detectors, - x_logicals, + x_dem_outputs, z_detectors, - z_logicals, + z_dem_outputs, } => { - let x = ErrorMechanism::from_sorted(x_detectors.clone(), x_logicals.clone()); - let z = ErrorMechanism::from_sorted(z_detectors.clone(), z_logicals.clone()); + let x = FaultMechanism::from_sorted(x_detectors.clone(), x_dem_outputs.clone()); + let z = FaultMechanism::from_sorted(z_detectors.clone(), z_dem_outputs.clone()); Some((x, z)) } - ErrorSourceType::Direct => None, + FaultSourceType::Direct | FaultSourceType::DirectOneSidedComponent => None, } } + + /// Returns the per-location component effects for a direct multi-location source. + #[must_use] + pub fn direct_component_effects(&self) -> Option<(FaultMechanism, FaultMechanism)> { + self.direct_component_effects.clone() + } +} + +/// Aggregated source-tracked information for one unique effect. +#[derive(Debug, Clone)] +pub struct ContributionEffectSummary { + /// The detector/DEM-output effect being summarized. + pub effect: FaultMechanism, + /// Total number of contributing sources for this effect. + pub num_contributions: usize, + /// Total probability summed over contributing sources. + pub total_probability: f64, + /// Number of direct contributions. + pub direct_count: usize, + /// Total probability from direct contributions. + pub direct_probability: f64, + /// Number of Y-decomposed contributions. + pub y_decomposed_count: usize, + /// Total probability from Y-decomposed contributions. + pub y_decomposed_probability: f64, + /// Number of builder-marked graphlike-decomposable two-qubit sources for this effect. + /// + /// This is only non-zero for 2-detector, 0-DEM-output effects. It reflects the + /// dormant representation-diversity bookkeeping recorded by the DEM builder. + pub graphlike_decomposable_count: u32, +} + +/// Structured summary of how tracked contributions render before final regrouping. +#[derive(Debug, Clone)] +pub struct ContributionRenderSummary { + /// Original full detector/DEM-output effect before rendering. + pub effect: FaultMechanism, + /// Rendered targets string that this contribution group maps to. + pub rendered_targets: String, + /// Number of tracked contributions in this pre-regroup bucket. + pub num_contributions: usize, + /// Total probability in this pre-regroup bucket. + pub total_probability: f64, + /// Probability after combining same-target contributions within this bucket. + pub combined_probability: f64, + /// Counts of source types in this bucket. + pub source_type_counts: BTreeMap, + /// Probability totals of source types in this bucket. + pub source_type_probabilities: BTreeMap, + /// Counts of direct source families in this bucket. + pub direct_source_family_counts: BTreeMap, + /// Probability totals of direct source families in this bucket. + pub direct_source_family_probabilities: BTreeMap, +} + +/// Per-contribution render record before final regrouping. +/// +/// This keeps the exact rendered target string attached to one tracked +/// contribution, without aggregating inside the pre-regroup bucket. It is a +/// lower-level view than [`ContributionRenderSummary`] and is useful for +/// inspecting within-effect render policies. +#[derive(Debug, Clone)] +pub struct ContributionRenderRecord { + /// Rendered targets string that this contribution maps to. + pub rendered_targets: String, + /// Coarse render strategy used for this contribution. + pub render_strategy: ContributionRenderStrategy, + /// Optional targets implied by recorded direct component effects. + /// + /// This is descriptive only: it does not imply the current render pass uses + /// these targets. + pub recorded_component_targets: Option, + /// Original tracked contribution before regrouping. + pub contribution: FaultContribution, +} + +/// Coarse render strategy used for one contribution in the decomposed DEM pass. +#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] +pub enum ContributionRenderStrategy { + /// Used source-specific decomposition components. + SourceComponents, + /// Used recorded direct-source component targets instead of the direct edge. + RecordedComponents, + /// Kept a 2-detector, 0-DEM-output effect graphlike as-is. + TwoDetectorDirect, + /// Decomposed a hyperedge using graphlike effect decomposition. + HyperedgeGraphlike, + /// Rendered directly from the full effect. + EffectDirect, +} + +/// Policy for rendering direct 2-detector effects in decomposed DEM output. +#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] +pub enum TwoDetectorDirectRenderPolicy { + /// Preserve the current direct-edge rendering. + KeepDirect, + /// Prefer recorded builder-time component targets when they differ from the + /// direct edge. This is intended for source-aware render experiments. + PreferRecordedComponents, } // ============================================================================ // Error Mechanism // ============================================================================ -/// An error mechanism: a set of detectors and logical observables that flip together. +/// A fault mechanism: a set of detectors and `L` targets that flip together. /// /// When an error occurs, it flips a specific set of detectors and may flip -/// logical observables. Mechanisms with the same effect are aggregated together. +/// `L` targets. Mechanisms with the same effect are aggregated together. /// -/// The detectors and logicals are stored in sorted order for canonical representation. +/// Detector and `L` target indices are stored in sorted order for canonical representation. #[derive(Clone, Default)] -pub struct ErrorMechanism { +pub struct FaultMechanism { /// Detector indices that flip together (sorted). pub detectors: SmallVec<[u32; 4]>, - /// Logical observable indices that flip together (sorted). - pub logicals: SmallVec<[u32; 2]>, + /// DEM `L` target indices that flip together (sorted). + /// + /// The field name follows Stim's DEM-output terminology. + /// New code should treat these as `L` target output channels. + pub dem_outputs: SmallVec<[u32; 2]>, } -impl ErrorMechanism { - /// Creates a new empty error mechanism. +impl FaultMechanism { + /// Creates a new empty fault mechanism. #[must_use] pub fn new() -> Self { Self::default() } - /// Creates a mechanism from unsorted detector and logical indices. + /// Creates a mechanism from unsorted detector and DEM-output indices. #[must_use] pub fn from_unsorted( detectors: impl IntoIterator, - logicals: impl IntoIterator, + dem_outputs: impl IntoIterator, ) -> Self { let mut dets: SmallVec<[u32; 4]> = detectors.into_iter().collect(); - let mut logs: SmallVec<[u32; 2]> = logicals.into_iter().collect(); + let mut dem_outputs: SmallVec<[u32; 2]> = dem_outputs.into_iter().collect(); dets.sort_unstable(); - logs.sort_unstable(); + dem_outputs.sort_unstable(); Self { detectors: dets, - logicals: logs, + dem_outputs, } } - /// Creates a mechanism from pre-sorted detector and logical indices. + /// Creates a mechanism from pre-sorted detector and DEM-output indices. #[must_use] - pub fn from_sorted(detectors: SmallVec<[u32; 4]>, logicals: SmallVec<[u32; 2]>) -> Self { + pub fn from_sorted(detectors: SmallVec<[u32; 4]>, dem_outputs: SmallVec<[u32; 2]>) -> Self { debug_assert!( detectors.windows(2).all(|w| w[0] <= w[1]), "detectors must be sorted" ); debug_assert!( - logicals.windows(2).all(|w| w[0] <= w[1]), - "logicals must be sorted" + dem_outputs.windows(2).all(|w| w[0] <= w[1]), + "dem_outputs must be sorted" ); Self { detectors, - logicals, + dem_outputs, } } @@ -213,7 +561,7 @@ impl ErrorMechanism { #[inline] #[must_use] pub fn is_empty(&self) -> bool { - self.detectors.is_empty() && self.logicals.is_empty() + self.detectors.is_empty() && self.dem_outputs.is_empty() } /// Returns the number of detectors in this mechanism. @@ -223,11 +571,11 @@ impl ErrorMechanism { self.detectors.len() } - /// Returns the number of logicals in this mechanism. + /// Returns the number of outputs in the DEM `L` namespace. #[inline] #[must_use] - pub fn num_logicals(&self) -> usize { - self.logicals.len() + pub fn num_dem_outputs(&self) -> usize { + self.dem_outputs.len() } /// XOR this mechanism with another, returning the combined effect. @@ -237,28 +585,29 @@ impl ErrorMechanism { pub fn xor(&self, other: &Self) -> Self { Self { detectors: symmetric_difference_4(&self.detectors, &other.detectors), - logicals: symmetric_difference_2(&self.logicals, &other.logicals), + dem_outputs: symmetric_difference_2(&self.dem_outputs, &other.dem_outputs), } } /// Returns true if this mechanism is graphlike. /// - /// A graphlike mechanism has at most 2 detectors and at most 1 logical observable. - /// MWPM decoders can only handle graphlike errors directly. + /// A graphlike mechanism has at most 2 detectors. + /// DEM outputs do not affect graph-likeness; MWPM decoders attach them as + /// frame-change masks on graph edges. #[inline] #[must_use] pub fn is_graphlike(&self) -> bool { - self.detectors.len() <= 2 && self.logicals.len() <= 1 + self.detectors.len() <= 2 } /// Returns true if this mechanism is a hyperedge (not graphlike). /// - /// Hyperedge mechanisms have 3+ detectors or 2+ logicals and need to be - /// decomposed into graphlike components for MWPM decoders. + /// Hyperedge mechanisms have 3+ detectors and need to be decomposed into + /// graphlike components for MWPM decoders. #[inline] #[must_use] pub fn is_hyperedge(&self) -> bool { - self.detectors.len() > 2 || self.logicals.len() > 1 + self.detectors.len() > 2 } } @@ -320,42 +669,42 @@ fn symmetric_difference_2(a: &SmallVec<[u32; 2]>, b: &SmallVec<[u32; 2]>) -> Sma result } -impl PartialEq for ErrorMechanism { +impl PartialEq for FaultMechanism { fn eq(&self, other: &Self) -> bool { - self.detectors == other.detectors && self.logicals == other.logicals + self.detectors == other.detectors && self.dem_outputs == other.dem_outputs } } -impl Eq for ErrorMechanism {} +impl Eq for FaultMechanism {} -impl Hash for ErrorMechanism { +impl Hash for FaultMechanism { fn hash(&self, state: &mut H) { self.detectors.hash(state); - self.logicals.hash(state); + self.dem_outputs.hash(state); } } -impl PartialOrd for ErrorMechanism { +impl PartialOrd for FaultMechanism { fn partial_cmp(&self, other: &Self) -> Option { Some(self.cmp(other)) } } -impl Ord for ErrorMechanism { +impl Ord for FaultMechanism { fn cmp(&self, other: &Self) -> Ordering { self.detectors .cmp(&other.detectors) - .then_with(|| self.logicals.cmp(&other.logicals)) + .then_with(|| self.dem_outputs.cmp(&other.dem_outputs)) } } -impl fmt::Debug for ErrorMechanism { +impl fmt::Debug for FaultMechanism { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!( f, - "ErrorMechanism(dets={:?}, logs={:?})", + "FaultMechanism(dets={:?}, dem_outputs={:?})", self.detectors.as_slice(), - self.logicals.as_slice() + self.dem_outputs.as_slice() ) } } @@ -364,23 +713,23 @@ impl fmt::Debug for ErrorMechanism { // Decomposed Error // ============================================================================ -/// A decomposed error mechanism with optional decomposition into graphlike parts. +/// A decomposed fault mechanism with optional decomposition into graphlike parts. /// /// When an error affects 3+ detectors (a hyperedge), it can be decomposed into /// a combination of graphlike errors (affecting 1-2 detectors each) connected /// by `^` separators indicating XOR composition. #[derive(Clone, Debug)] -pub struct DecomposedError { - /// The component error mechanisms (separated by `^` in DEM format). +pub struct DecomposedFault { + /// The component fault mechanisms (separated by `^` in DEM format). /// For graphlike errors, this has a single element. /// For decomposed hyperedges, this has multiple elements. - pub components: SmallVec<[ErrorMechanism; 2]>, + pub components: SmallVec<[FaultMechanism; 2]>, } -impl DecomposedError { +impl DecomposedFault { /// Creates a new decomposed error from a single mechanism. #[must_use] - pub fn single(mechanism: ErrorMechanism) -> Self { + pub fn single(mechanism: FaultMechanism) -> Self { let mut components = SmallVec::new(); components.push(mechanism); Self { components } @@ -388,7 +737,7 @@ impl DecomposedError { /// Creates a decomposed error from multiple components. #[must_use] - pub fn decomposed(components: impl IntoIterator) -> Self { + pub fn decomposed(components: impl IntoIterator) -> Self { Self { components: components.into_iter().collect(), } @@ -396,8 +745,8 @@ impl DecomposedError { /// Returns the full effect of this error (XOR of all components). #[must_use] - pub fn full_effect(&self) -> ErrorMechanism { - let mut result = ErrorMechanism::new(); + pub fn full_effect(&self) -> FaultMechanism { + let mut result = FaultMechanism::new(); for component in &self.components { result = result.xor(component); } @@ -420,8 +769,8 @@ impl DecomposedError { for &det in &comp.detectors { targets.push(format!("D{det}")); } - for &log in &comp.logicals { - targets.push(format!("L{log}")); + for &dem_output in &comp.dem_outputs { + targets.push(format!("L{dem_output}")); } targets.join(" ") }) @@ -436,7 +785,7 @@ impl DecomposedError { /// Finds all valid graphlike decompositions of a hyperedge mechanism. /// -/// A hyperedge is an error mechanism with 3+ detectors or 2+ logicals. +/// A hyperedge is an fault mechanism with 3+ detectors. /// For MWPM decoders, hyperedges must be decomposed into XOR combinations /// of graphlike components (≤2 detectors, ≤1 logical each). /// @@ -447,165 +796,319 @@ impl DecomposedError { /// /// # Returns /// -/// A vector of decompositions, where each decomposition is a vector of -/// graphlike mechanisms whose XOR equals the original hyperedge. -/// Returns an empty vector if no valid decomposition exists. +/// A graphlike decomposition whose XOR equals the original hyperedge. +/// Returns `None` if no valid decomposition exists. /// /// # Algorithm /// -/// Uses a type-aware search that distinguishes between: -/// - 2-part decompositions (hyperedge = A XOR B) -/// - 3-part decompositions (hyperedge = A XOR B XOR C) +/// Uses a detector-driven recursive search over graphlike components whose +/// detector sets are subsets of the hyperedge. This is closer to Stim's +/// decomposition strategy than the older fixed-width 2-part/3-part search, +/// and it allows decompositions into 4+ graphlike pieces when needed. /// -/// This matches Stim's behavior of outputting: -/// - 1 form if only one decomposition size exists -/// - 2 forms if both 2-part and 3-part decompositions exist +/// Decompositions are filtered to only include components whose detectors are +/// subsets of the original hyperedge's detectors, matching Stim's behavior of +/// not introducing extra detector symptoms. /// -/// Additionally, decompositions are filtered to only include those where -/// all component detectors are subsets of the original hyperedge's detectors. -/// This matches Stim's behavior of not introducing extra detectors. +/// # Selection /// -/// # Steps -/// 1. Find decompositions, preferring those with smaller components -/// 2. Return one 2-part and one 3-part if both exist -pub fn find_hyperedge_decompositions( - hyperedge: &ErrorMechanism, - graphlike_set: &HashSet, -) -> Vec> { - // If already graphlike, no decomposition needed - if hyperedge.is_graphlike() { - return vec![vec![hyperedge.clone()]]; - } - - // Collect the set of detectors in the hyperedge - let hyperedge_dets: HashSet = hyperedge.detectors.iter().copied().collect(); - - // Helper to check if all detectors in a decomposition are in the hyperedge - let decomp_dets_valid = |decomp: &[ErrorMechanism]| -> bool { - decomp +/// The search returns the first valid decomposition found using a deterministic +/// ordering that prefers detector pairs before singlets, similar to Stim's +/// decompose pass over known graphlike symptoms. +#[cfg(test)] +fn find_hyperedge_decomposition( + hyperedge: &FaultMechanism, + graphlike_set: &BTreeSet, +) -> Option> { + GraphlikeDecompositionIndex::new(graphlike_set).find_hyperedge_decomposition(hyperedge) +} + +struct GraphlikeDecompositionIndex { + graphlike_set: BTreeSet, + /// Indexed by detector ID; see `SingletonDecompositionIndex` for the same + /// pattern and rationale. Detector IDs are dense `0..num_detectors`. + candidates_by_detector: Vec>, +} + +impl GraphlikeDecompositionIndex { + fn new(graphlike_set: &BTreeSet) -> Self { + let max_det = graphlike_set .iter() - .flat_map(|m| m.detectors.iter()) - .all(|d| hyperedge_dets.contains(d)) - }; + .flat_map(|c| c.detectors.iter().copied()) + .max(); - // Helper to compute the maximum component size (prefer smaller) - let max_component_size = |decomp: &[ErrorMechanism]| -> usize { - decomp.iter().map(|m| m.detectors.len()).max().unwrap_or(0) - }; + let mut candidates_by_detector: Vec> = + max_det.map_or_else(Vec::new, |m| vec![Vec::new(); m as usize + 1]); - // Find best 2-part and best 3-part decomposition (prefer smaller components) - let mut two_part_decomp: Option> = None; - let mut two_part_max_size: usize = usize::MAX; - let mut three_part_decomp: Option> = None; - let mut three_part_max_size: usize = usize::MAX; + for candidate in graphlike_set { + for &det in &candidate.detectors { + candidates_by_detector[det as usize].push(candidate.clone()); + } + } + for values in &mut candidates_by_detector { + values.sort_by(|a, b| { + b.detectors + .len() + .cmp(&a.detectors.len()) + .then_with(|| a.cmp(b)) + }); + } + Self { + graphlike_set: graphlike_set.clone(), + candidates_by_detector, + } + } - // Try 2-part decompositions - for g1 in graphlike_set { - // g1 must share at least one element with the hyperedge - if !shares_element(g1, hyperedge) { - continue; + fn find_hyperedge_decomposition( + &self, + hyperedge: &FaultMechanism, + ) -> Option> { + // If already graphlike, no decomposition needed + if hyperedge.is_graphlike() { + return Some(vec![hyperedge.clone()]); } - let remainder = hyperedge.xor(g1); + // Collect the set of detectors in the hyperedge + let hyperedge_dets: BTreeSet = hyperedge.detectors.iter().copied().collect(); - // If remainder is graphlike and in the set, we found a 2-part decomposition - if remainder.is_graphlike() && graphlike_set.contains(&remainder) { - // Verify: g1 XOR remainder should equal hyperedge - let check = g1.xor(&remainder); - if check != *hyperedge { - continue; - } + let decomp_dets_valid = |decomp: &[FaultMechanism]| -> bool { + decomp + .iter() + .flat_map(|m| m.detectors.iter()) + .all(|d| hyperedge_dets.contains(d)) + }; - // Canonicalize ordering - let decomp = if g1 < &remainder { - vec![g1.clone(), remainder] - } else { - vec![remainder, g1.clone()] - }; + let mut memo = BTreeMap::new(); + let result = self.search_decomposition(hyperedge, &mut memo); + result.filter(|decomp| decomp_dets_valid(decomp)) + } - // Check that all detectors in components are in the hyperedge - if decomp_dets_valid(&decomp) { - let size = max_component_size(&decomp); - if size < two_part_max_size { - two_part_max_size = size; - two_part_decomp = Some(decomp); - } - } + fn search_decomposition( + &self, + remaining: &FaultMechanism, + memo: &mut BTreeMap>>, + ) -> Option> { + if let Some(cached) = memo.get(remaining) { + return cached.clone(); } - } - // Try 3-part decompositions - for g1 in graphlike_set { - if !shares_element(g1, hyperedge) { - continue; + if remaining.is_empty() { + let result = Some(Vec::new()); + memo.insert(remaining.clone(), result.clone()); + return result; } - let after_g1 = hyperedge.xor(g1); - if after_g1.is_graphlike() { - continue; // Would be a 2-part decomposition + if remaining.is_graphlike() && self.graphlike_set.contains(remaining) { + let result = Some(vec![remaining.clone()]); + memo.insert(remaining.clone(), result.clone()); + return result; } - for g2 in graphlike_set { - if g2 <= g1 { - continue; // Avoid duplicates - } - if !shares_element(g2, &after_g1) { - continue; - } + if let Some(&pivot) = remaining.detectors.first() + && let Some(candidates) = self.candidates_by_detector.get(pivot as usize) + { + for candidate in candidates { + if !candidate + .detectors + .iter() + .all(|d| remaining.detectors.contains(d)) + { + continue; + } + if !shares_element(candidate, remaining) { + continue; + } - let after_g2 = after_g1.xor(g2); + let next = remaining.xor(candidate); - // If remainder is graphlike and in the set, we found a 3-part decomposition - if after_g2.is_graphlike() && graphlike_set.contains(&after_g2) { - // Verify: g1 XOR g2 XOR after_g2 should equal hyperedge - let check = g1.xor(g2).xor(&after_g2); - if check != *hyperedge { + // Require strict detector-count progress to prevent cycles. + if next.detectors.len() >= remaining.detectors.len() { continue; } - let mut parts = vec![g1.clone(), g2.clone(), after_g2]; - parts.sort(); - - // Check that all detectors in components are in the hyperedge - if decomp_dets_valid(&parts) { - let size = max_component_size(&parts); - if size < three_part_max_size { - three_part_max_size = size; - three_part_decomp = Some(parts); - } + if let Some(suffix) = self.search_decomposition(&next, memo) { + let mut combined = Vec::with_capacity(suffix.len() + 1); + combined.push(candidate.clone()); + combined.extend(suffix); + combined.sort(); + let result = Some(combined); + memo.insert(remaining.clone(), result.clone()); + return result; } } } + + memo.insert(remaining.clone(), None); + None + } +} + +/// Finds a decomposition of a graphlike effect into singleton detector components. +/// +/// This is used for "maximal" decomposition modes that prefer singleton +/// detector symptoms whenever the required singleton effects already exist as +/// standalone mechanisms in the DEM. +fn find_singleton_decomposition( + effect: &FaultMechanism, + index: &SingletonDecompositionIndex, +) -> Option> { + if effect.is_empty() { + return Some(Vec::new()); + } + if effect.num_detectors() <= 1 { + return Some(vec![effect.clone()]); + } + if index.is_empty() { + return None; + } + + let mut memo: BTreeMap>> = BTreeMap::new(); + search_singleton_decomposition(effect, &index.candidates_by_detector, &mut memo) +} + +/// Pre-computed bucket of singleton (1-detector) mechanisms indexed by detector ID. +/// +/// Built once per render pass; detector IDs are dense `0..num_detectors`, so a +/// `Vec>` indexed by detector ID beats a `BTreeMap>` both on +/// lookup (O(1) vs O(log n)) and on per-call rebuild cost. Profiling flagged the +/// rebuild-per-call pattern as ~28% of `to_string_decomposed_maximally` time +/// before this was lifted out. +struct SingletonDecompositionIndex { + /// `candidates_by_detector[det]` lists every singleton mechanism whose sole + /// detector is `det`, sorted by `(dem_outputs.len, dem_outputs, detectors)` so the + /// decomposition search prefers simpler candidates deterministically. + candidates_by_detector: Vec>, +} + +impl SingletonDecompositionIndex { + fn new() -> Self { + Self { + candidates_by_detector: Vec::new(), + } + } + + fn from_contributions(contributions: &[FaultContribution]) -> Self { + let mut singletons: BTreeSet = BTreeSet::new(); + for contrib in contributions { + if contrib.effect.num_detectors() == 1 { + singletons.insert(contrib.effect.clone()); + } + } + + let Some(max_det) = singletons.iter().map(|c| c.detectors[0]).max() else { + return Self::new(); + }; + + let mut candidates_by_detector: Vec> = + vec![Vec::new(); max_det as usize + 1]; + for candidate in singletons { + let det = candidate.detectors[0] as usize; + candidates_by_detector[det].push(candidate); + } + for candidates in &mut candidates_by_detector { + candidates.sort_by(|a, b| { + a.dem_outputs + .len() + .cmp(&b.dem_outputs.len()) + .then_with(|| a.dem_outputs.cmp(&b.dem_outputs)) + .then_with(|| a.detectors.cmp(&b.detectors)) + }); + } + Self { + candidates_by_detector, + } + } + + fn is_empty(&self) -> bool { + self.candidates_by_detector.is_empty() } +} - // Combine results: output both types if available - let mut result = Vec::new(); - if let Some(decomp) = two_part_decomp { - result.push(decomp); +fn search_singleton_decomposition( + remaining: &FaultMechanism, + candidates_by_detector: &[Vec], + memo: &mut BTreeMap>>, +) -> Option> { + if let Some(cached) = memo.get(remaining) { + return cached.clone(); } - if let Some(decomp) = three_part_decomp { - result.push(decomp); + if remaining.is_empty() { + return Some(Vec::new()); } + + let Some(&first_det) = remaining.detectors.first() else { + memo.insert(remaining.clone(), None); + return None; + }; + + let result = candidates_by_detector + .get(first_det as usize) + .and_then(|candidates| { + for candidate in candidates { + let next = remaining.xor(candidate); + if next.num_detectors() >= remaining.num_detectors() { + continue; + } + if let Some(mut tail) = + search_singleton_decomposition(&next, candidates_by_detector, memo) + { + let mut parts = Vec::with_capacity(tail.len() + 1); + parts.push(candidate.clone()); + parts.append(&mut tail); + return Some(parts); + } + } + None + }); + + memo.insert(remaining.clone(), result.clone()); result } /// Checks if two mechanisms share at least one detector or logical. -fn shares_element(a: &ErrorMechanism, b: &ErrorMechanism) -> bool { +fn shares_element(a: &FaultMechanism, b: &FaultMechanism) -> bool { // Check detectors for d in &a.detectors { if b.detectors.contains(d) { return true; } } - // Check logicals - for l in &a.logicals { - if b.logicals.contains(l) { + // Check dem_outputs + for l in &a.dem_outputs { + if b.dem_outputs.contains(l) { return true; } } false } +fn convert_location_indices(location_indices: &[usize]) -> SmallVec<[u32; 2]> { + location_indices + .iter() + .map(|&idx| u32::try_from(idx).expect("fault location index must fit into u32")) + .collect() +} + +/// Converts a measurement record offset (Stim-style) to an absolute measurement index. +/// +/// Negative offsets count backward from the end of the measurement record +/// (`-1` is the last measurement). Positive offsets are treated as absolute +/// indices. +/// +/// Returns `None` whenever the resulting index would land outside +/// `0..num_measurements`. Callers should treat a `None` as a malformed input +/// (parser/user-supplied offset was too large or too negative); it is never +/// produced by internally-generated offsets, so silently dropping such a +/// contribution rather than panicking is the intended behavior. +#[must_use] +pub fn record_offset_to_absolute_index(num_measurements: usize, offset: i32) -> Option { + if offset < 0 { + num_measurements.checked_add_signed(isize::try_from(offset).ok()?) + } else { + usize::try_from(offset).ok() + } +} + // ============================================================================ // Detector Definition // ============================================================================ @@ -656,28 +1159,52 @@ impl DetectorDef { } // ============================================================================ -// Logical Observable +// DEM Outputs // ============================================================================ -/// A logical observable definition. +/// Metadata for a PECOS non-detector output. /// -/// Logical observables track the parity of certain measurement outcomes -/// to detect logical errors. +/// Observables are rendered as standard Stim `L` targets. Tracked operators +/// use the same metadata shape but live in a separate PECOS-only ID space and +/// are never rendered as `L`. #[derive(Debug, Clone)] -pub struct LogicalObservable { - /// Unique observable ID. +pub struct DemOutput { + /// Unique ID within this output's ID space. pub id: u32, - /// Measurement record offsets (negative indices from end of record). + /// Measurement record offsets (negative indices from end of record), when + /// this output is tied to measurement records. pub records: SmallVec<[i32; 4]>, + /// PECOS DEM output kind, when known. + pub kind: Option, + /// Pauli string whose flip is tracked, when this came from a Pauli + /// annotation or logical operator builder. + pub pauli: Option, + /// Optional user label. + pub label: Option, } -impl LogicalObservable { - /// Creates a new logical observable. +impl DemOutput { + /// Creates a new unclassified DEM output. #[must_use] pub fn new(id: u32) -> Self { Self { id, records: SmallVec::new(), + kind: None, + pauli: None, + label: None, + } + } + + /// Creates a DEM output from PECOS propagation metadata. + #[must_use] + pub fn from_metadata(id: u32, metadata: &DemOutputMetadata) -> Self { + Self { + id, + records: SmallVec::new(), + kind: Some(metadata.kind), + pauli: Some(metadata.pauli.clone()), + label: metadata.label.clone(), } } @@ -685,84 +1212,708 @@ impl LogicalObservable { #[must_use] pub fn with_records(mut self, records: impl IntoIterator) -> Self { self.records = records.into_iter().collect(); + self.kind.get_or_insert(DemOutputKind::Observable); self } -} -// ============================================================================ -// Noise Configuration -// ============================================================================ + /// Sets the DEM output kind. + #[must_use] + pub fn with_kind(mut self, kind: DemOutputKind) -> Self { + self.kind = Some(kind); + self + } -/// Noise model configuration for DEM generation. -#[derive(Debug, Clone, Copy)] -pub struct NoiseConfig { - /// Single-qubit depolarizing error rate. - pub p1: f64, - /// Two-qubit depolarizing error rate. - pub p2: f64, - /// Measurement error rate. - pub p_meas: f64, - /// Initialization (prep) error rate. - pub p_init: f64, -} + /// Sets the tracked Pauli string. + #[must_use] + pub fn with_pauli(mut self, mut pauli: PauliString) -> Self { + // A DEM output flip is an anticommutation property; global phase + // has no meaning for DEM/sampler output. + pauli.set_phase(pecos_core::QuarterPhase::PlusOne); + self.pauli = Some(pauli); + self + } -impl Default for NoiseConfig { - fn default() -> Self { - Self { - p1: 0.01, - p2: 0.01, - p_meas: 0.01, - p_init: 0.01, - } + /// Sets a user-facing label. + #[must_use] + pub fn with_label(mut self, label: impl Into) -> Self { + self.label = Some(label.into()); + self } -} -impl NoiseConfig { - /// Creates a new noise configuration. + /// Returns true when this DEM output is an observable. #[must_use] - pub fn new(p1: f64, p2: f64, p_meas: f64, p_init: f64) -> Self { - Self { - p1, - p2, - p_meas, - p_init, + pub fn is_observable(&self) -> bool { + match self.kind { + Some(DemOutputKind::Observable) => true, + Some(DemOutputKind::TrackedOperator) => false, + None => !self.records.is_empty(), } } - /// Creates a uniform noise configuration. + /// Returns true when this DEM output is a tracked Pauli operator. #[must_use] - pub fn uniform(p: f64) -> Self { + pub fn is_tracked_operator(&self) -> bool { + match self.kind { + Some(DemOutputKind::TrackedOperator) => true, + Some(DemOutputKind::Observable) => false, + None => self.pauli.is_some() && self.records.is_empty(), + } + } +} + +/// Error returned when parsing or applying PECOS DEM metadata JSON. +#[derive(Debug, Clone, PartialEq, Eq)] +pub struct PecosDemMetadataError { + message: String, +} + +impl PecosDemMetadataError { + fn new(message: impl Into) -> Self { Self { - p1: p, - p2: p, - p_meas: p, - p_init: p, + message: message.into(), } } + + /// Human-readable parse/apply error. + #[must_use] + pub fn message(&self) -> &str { + &self.message + } +} + +impl fmt::Display for PecosDemMetadataError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "{}", self.message) + } } +impl std::error::Error for PecosDemMetadataError {} + // ============================================================================ -// Detector Error Model +// Noise Configuration // ============================================================================ -/// A complete Detector Error Model (DEM). -/// -/// This represents the noise model of a quantum circuit. It maps mechanisms -/// (detector/logical effects) to their probabilities. +/// Per-Pauli fault probability weights. /// -/// # Aggregation Modes +/// Maps `PauliString` to relative probability. Entries must sum to ~1.0. +/// Used to customize the fault distribution for single-qubit or two-qubit gates. /// -/// The DEM supports two modes controlled by `aggregate`: +/// # Examples /// -/// - **Aggregated mode** (`aggregate = true`): Mechanisms with the same effect -/// are combined into a single entry using the independent error formula. -/// This is more compact but loses information about noise sources. +/// ```ignore +/// use pecos_core::pauli::constructors::{X, Y, Z}; /// -/// - **Non-aggregated mode** (`aggregate = false`, default): Each noise source -/// is kept as a separate entry. This preserves correlation information and -/// allows advanced decoders to understand the noise structure. +/// // Single-qubit: biased toward dephasing +/// let w = PauliWeights::from([(Z(0), 0.8), (X(0), 0.1), (Y(0), 0.1)]); /// -/// # Decomposed Entries +/// // Two-qubit: uniform (convenience) +/// let w = PauliWeights::uniform_2q(); +/// ``` +#[derive(Debug, Clone)] +pub struct PauliWeights { + /// (`PauliString`, weight) pairs. Weights must sum to ~1.0. + entries: Vec<(pecos_core::PauliString, f64)>, +} + +impl PauliWeights { + /// Create from an iterator of `(PauliString, weight)` pairs. + /// + /// Validates that weights sum to approximately 1.0 (within 1e-6). + /// + /// # Panics + /// + /// Panics if weights don't sum to ~1.0 or if any weight is negative. + pub fn new(entries: impl IntoIterator) -> Self { + let entries: Vec<_> = entries.into_iter().collect(); + let sum: f64 = entries.iter().map(|(_, w)| w).sum(); + assert!( + (sum - 1.0).abs() < 1e-6, + "PauliWeights must sum to 1.0, got {sum}" + ); + for (ps, w) in &entries { + assert!(*w >= 0.0, "Weight for {ps} must be non-negative, got {w}"); + } + Self { entries } + } + + /// Uniform weights for single-qubit gates: X, Y, Z each with 1/3. + #[must_use] + pub fn uniform_1q() -> Self { + use pecos_core::pauli::constructors::{X, Y, Z}; + Self { + entries: vec![(X(0), 1.0 / 3.0), (Y(0), 1.0 / 3.0), (Z(0), 1.0 / 3.0)], + } + } + + /// Uniform weights for two-qubit gates: all 15 non-identity Paulis at 1/15. + #[must_use] + pub fn uniform_2q() -> Self { + use pecos_core::pauli::constructors::{X, Y, Z}; + let w = 1.0 / 15.0; + Self { + entries: vec![ + (X(1), w), + (Y(1), w), + (Z(1), w), + (X(0), w), + (X(0) & X(1), w), + (X(0) & Y(1), w), + (X(0) & Z(1), w), + (Y(0), w), + (Y(0) & X(1), w), + (Y(0) & Y(1), w), + (Y(0) & Z(1), w), + (Z(0), w), + (Z(0) & X(1), w), + (Z(0) & Y(1), w), + (Z(0) & Z(1), w), + ], + } + } + + /// Look up the weight for a specific `PauliString`. + /// + /// Matches by Pauli type pattern only, ignoring qubit IDs. + /// E.g., `X(3) & Z(7)` matches a weight entry `X(0) & Z(1)` because + /// both have the pattern [X, Z] (sorted by qubit position). + #[must_use] + pub fn weight_for(&self, pauli: &pecos_core::PauliString) -> f64 { + let query_pattern = pauli_pattern(pauli); + self.entries + .iter() + .find(|(ps, _)| pauli_pattern(ps) == query_pattern) + .map_or(0.0, |(_, w)| *w) + } + + /// Get all entries as `(PauliString, weight)` pairs. + #[must_use] + pub fn entries(&self) -> &[(pecos_core::PauliString, f64)] { + &self.entries + } +} + +impl From<[(pecos_core::PauliString, f64); N]> for PauliWeights { + fn from(entries: [(pecos_core::PauliString, f64); N]) -> Self { + Self::new(entries) + } +} + +/// Noise model configuration for circuit-level fault analysis. +#[derive(Debug, Clone)] +pub struct NoiseConfig { + /// Single-qubit gate error rate. + pub p1: f64, + /// Two-qubit gate error rate. + pub p2: f64, + /// Measurement error rate. + pub p_meas: f64, + /// Initialization (prep) error rate. + pub p_prep: f64, + /// Idle gate error rate per time unit. + /// + /// The actual error probability for an idle gate is `p_idle * duration` + /// (clamped to [0, 1]), where `duration` is the gate's `TimeUnits` value. + /// Default is 0.0 (no idle noise). + pub p_idle: f64, + /// Optional T1 relaxation time (in the same time units as idle duration). + /// + /// When set (along with T2), idle noise uses the Pauli-twirled + /// amplitude damping + dephasing model instead of uniform depolarizing. + /// This gives biased noise: P(Z) > P(X) = P(Y). + pub t1: Option, + /// Optional T2 dephasing time (must satisfy T2 <= 2*T1). + pub t2: Option, + /// Optional per-Pauli weights for single-qubit gates. + /// + /// Maps each Pauli fault to its relative probability. Must sum to ~1.0. + /// Default (None) = uniform depolarizing. + pub p1_weights: Option, + /// Optional per-Pauli weights for two-qubit gates. + /// + /// Maps each two-qubit Pauli fault to its relative probability. Must sum to ~1.0. + /// Default (None) = uniform depolarizing. + pub p2_weights: Option, + /// Coherent idle RZ rotation angle per time unit. + /// + /// When set (> 0), idle gates contribute a coherent Z rotation in addition + /// to any stochastic idle noise. Idle fault locations with the same + /// detector set have their angles accumulated coherently (angles add), + /// giving probability sin²(total_angle/2) instead of independent combination. + /// + /// This is the EEG H-type noise model for idle gates. Default is 0.0. + pub idle_rz: f64, +} + +/// Per-Pauli error probabilities for a single qubit. +#[derive(Debug, Clone, Copy)] +pub struct PauliProbs { + /// Probability of X error. + pub px: f64, + /// Probability of Y error. + pub py: f64, + /// Probability of Z error. + pub pz: f64, +} + +impl PauliProbs { + /// Total error probability (px + py + pz). + #[must_use] + pub fn total(&self) -> f64 { + self.px + self.py + self.pz + } + + /// Uniform depolarizing: each Pauli with probability p/3. + #[must_use] + pub fn depolarizing(p: f64) -> Self { + Self { + px: p / 3.0, + py: p / 3.0, + pz: p / 3.0, + } + } + + /// Pauli-twirled T1/T2 noise for idle duration t. + /// + /// Approximates the combined amplitude damping (T1) and pure + /// dephasing (T2) channel as a Pauli channel via Pauli twirling: + /// + /// P(X) = P(Y) = (1 - e^{-t/T1}) / 4 + /// P(Z) = (1 - e^{-t/T2}) / 2 - (1 - e^{-t/T1}) / 4 + /// + /// Requires T2 <= 2*T1 (physical constraint). + #[must_use] + pub fn from_t1_t2(t: f64, t1: f64, t2: f64) -> Self { + let gamma = 1.0 - (-t / t1).exp(); // amplitude damping parameter + let lambda_t2 = 1.0 - (-t / t2).exp(); // total dephasing parameter + + let px = gamma / 4.0; + let py = gamma / 4.0; + let pz = (lambda_t2 / 2.0 - gamma / 4.0).max(0.0); + + Self { px, py, pz } + } +} + +impl Default for NoiseConfig { + fn default() -> Self { + Self { + p1: 0.01, + p2: 0.01, + p_meas: 0.01, + p_prep: 0.01, + p_idle: 0.0, + t1: None, + t2: None, + p1_weights: None, + p2_weights: None, + idle_rz: 0.0, + } + } +} + +impl NoiseConfig { + /// Creates a new noise configuration (idle defaults to `None`). + #[must_use] + pub fn new(p1: f64, p2: f64, p_meas: f64, p_prep: f64) -> Self { + Self { + p1, + p2, + p_meas, + p_prep, + p_idle: 0.0, + t1: None, + t2: None, + p1_weights: None, + p2_weights: None, + idle_rz: 0.0, + } + } + + /// Creates a new noise configuration with uniform depolarizing idle noise. + #[must_use] + pub fn with_idle(p1: f64, p2: f64, p_meas: f64, p_prep: f64, p_idle: f64) -> Self { + Self { + p1, + p2, + p_meas, + p_prep, + p_idle, + t1: None, + t2: None, + p1_weights: None, + p2_weights: None, + idle_rz: 0.0, + } + } + + /// Creates a uniform noise configuration (including depolarizing idle). + #[must_use] + pub fn uniform(p: f64) -> Self { + Self { + p1: p, + p2: p, + p_meas: p, + p_prep: p, + p_idle: p, + t1: None, + t2: None, + p1_weights: None, + p2_weights: None, + idle_rz: 0.0, + } + } + + /// Sets the idle noise rate on an existing config (uniform depolarizing). + #[must_use] + pub fn set_idle(mut self, p_idle: f64) -> Self { + self.p_idle = p_idle; + self + } + + /// Sets T1/T2 relaxation times for idle noise. + /// + /// When set, idle gates use the Pauli-twirled T1/T2 model instead of + /// uniform depolarizing. This produces biased noise where Z errors + /// (dephasing) are more likely than X/Y errors (relaxation). + /// + /// T1 and T2 are in the same time units as idle gate durations. + /// Must satisfy T2 <= 2*T1 (physical constraint). + /// + /// # Panics + /// + /// Panics if `t2 > 2 * t1`, which violates the physical constraint + /// that the dephasing time cannot exceed twice the relaxation time. + #[must_use] + pub fn set_t1_t2(mut self, t1: f64, t2: f64) -> Self { + assert!( + t2 <= 2.0 * t1, + "T2 ({t2}) must be <= 2*T1 ({}) (physical constraint)", + 2.0 * t1 + ); + self.t1 = Some(t1); + self.t2 = Some(t2); + self + } + + /// Sets custom per-Pauli weights for single-qubit gates. + /// + /// ```ignore + /// use pecos_core::pauli::constructors::{X, Y, Z}; + /// noise.set_p1_weights(PauliWeights::from([ + /// (X(0), 0.1), (Y(0), 0.1), (Z(0), 0.8), + /// ])); + /// ``` + #[must_use] + pub fn set_p1_weights(mut self, weights: PauliWeights) -> Self { + self.p1_weights = Some(weights); + self + } + + /// Sets custom per-Pauli weights for two-qubit gates. + #[must_use] + pub fn set_p2_weights(mut self, weights: PauliWeights) -> Self { + self.p2_weights = Some(weights); + self + } + + /// Sets idle noise from a coherent RZ rotation angle per time unit. + /// + /// Converts `idle_rz` (the angle theta of an RZ(theta) rotation applied + /// per idle time unit) to an equivalent stochastic Z-biased noise: + /// + /// P(Z) = sin^2(theta/2) per idle time unit + /// P(X) = P(Y) = 0 + /// + /// This is the exact Pauli twirling of a pure dephasing channel and + /// gives the non-EEG DEM builder correct idle noise behavior including + /// proper correlations through the fault influence map. + #[must_use] + pub fn set_idle_rz(mut self, idle_rz: f64) -> Self { + self.idle_rz = idle_rz; + let pz = (idle_rz / 2.0).sin().powi(2); + // Use T1/T2 model: T1=infinity (no amplitude damping), T2 chosen to match pz. + // From the T1/T2 model: pz = (1 - exp(-t/T2))/2 for T1=inf, t=1. + // Solve: T2 = -1/ln(1 - 2*pz) + // This provides the stochastic fallback for non-coherent code paths. + if pz > 0.0 && pz < 0.5 { + let t2 = -1.0 / (1.0 - 2.0 * pz).ln(); + let t1 = 1e15; // effectively infinity + self.t1 = Some(t1); + self.t2 = Some(t2); + } + self.p_idle = 0.0; + self + } + + /// Compute per-Pauli idle noise probabilities for a given duration. + /// + /// If T1/T2 are set, uses the Pauli-twirled model (biased noise). + /// Otherwise, uses uniform depolarizing with `p_idle * duration`. + #[must_use] + pub fn idle_pauli_probs(&self, duration: f64) -> PauliProbs { + if let (Some(t1), Some(t2)) = (self.t1, self.t2) { + PauliProbs::from_t1_t2(duration, t1, t2) + } else { + PauliProbs::depolarizing((self.p_idle * duration).min(1.0)) + } + } +} + +/// Extract the Pauli type pattern from a `PauliString`, ignoring qubit IDs. +/// +/// Returns the sequence of Pauli types sorted by qubit position. +/// E.g., X(3) & Z(7) -> [X, Z], same as X(0) & Z(1) -> [X, Z]. +fn pauli_pattern(ps: &pecos_core::PauliString) -> Vec { + ps.paulis().iter().map(|&(p, _)| p).collect() +} + +fn pecos_metadata_dem_output_value(target: &DemOutput) -> serde_json::Value { + serde_json::json!({ + "id": target.id, + "kind": target.kind.map_or("dem_output", DemOutputKind::as_str), + "label": target.label, + "pauli": target.pauli.as_ref().map(PauliString::to_sparse_str), + "records": target.records.iter().copied().collect::>(), + }) +} + +#[derive(Debug, Clone, Default)] +struct ParsedPecosDemMetadata { + observables: Vec, + tracked_ops: Vec, +} + +pub(crate) fn parse_pecos_dem_metadata_line( + line: &str, +) -> Result { + let line = line.trim(); + let (prefix, payload, forced_kind) = + if let Some(payload) = line.strip_prefix("pecos_tracked_op") { + ( + "pecos_tracked_op", + payload.trim(), + Some(DemOutputKind::TrackedOperator), + ) + } else if let Some(payload) = line.strip_prefix("pecos_observable") { + ( + "pecos_observable", + payload.trim(), + Some(DemOutputKind::Observable), + ) + } else { + return Err(PecosDemMetadataError::new( + "missing PECOS DEM metadata prefix", + )); + }; + if payload.is_empty() { + return Err(PecosDemMetadataError::new(format!( + "{prefix} is missing its JSON payload" + ))); + } + + let value: serde_json::Value = serde_json::from_str(payload).map_err(|err| { + PecosDemMetadataError::new(format!("invalid {prefix} JSON payload: {err}")) + })?; + let mut output = parse_pecos_metadata_dem_output(0, &value)?; + if let Some(kind) = forced_kind { + output.kind = Some(kind); + } + if output.is_tracked_operator() && !output.records.is_empty() { + return Err(PecosDemMetadataError::new( + "tracked operator metadata cannot have measurement records", + )); + } + Ok(output) +} + +fn parse_pecos_metadata_json(json: &str) -> Result { + let root: serde_json::Value = serde_json::from_str(json).map_err(|err| { + PecosDemMetadataError::new(format!("invalid PECOS DEM metadata JSON: {err}")) + })?; + + let format = root + .get("format") + .and_then(serde_json::Value::as_str) + .ok_or_else(|| PecosDemMetadataError::new("missing metadata format"))?; + if format != "pecos.dem.metadata" { + return Err(PecosDemMetadataError::new(format!( + "unsupported metadata format: {format}" + ))); + } + + let version = root + .get("version") + .and_then(serde_json::Value::as_u64) + .ok_or_else(|| PecosDemMetadataError::new("missing metadata version"))?; + if version != 1 { + return Err(PecosDemMetadataError::new(format!( + "unsupported PECOS DEM metadata version: {version}" + ))); + } + + let parse_array = |name: &str, + kind: DemOutputKind| + -> Result, PecosDemMetadataError> { + let Some(values) = root.get(name) else { + return Ok(Vec::new()); + }; + let values = values.as_array().ok_or_else(|| { + PecosDemMetadataError::new(format!("{name} metadata is not an array")) + })?; + values + .iter() + .enumerate() + .map(|(idx, value)| { + let mut output = parse_pecos_metadata_dem_output(idx, value)?; + output.kind = Some(kind); + if kind == DemOutputKind::TrackedOperator && !output.records.is_empty() { + return Err(PecosDemMetadataError::new(format!( + "tracked operator metadata {idx} cannot have measurement records" + ))); + } + Ok(output) + }) + .collect() + }; + + let parsed = ParsedPecosDemMetadata { + observables: parse_array("observables", DemOutputKind::Observable)?, + tracked_ops: parse_array("tracked_ops", DemOutputKind::TrackedOperator)?, + }; + + if root.get("observables").is_none() && root.get("tracked_ops").is_none() { + return Err(PecosDemMetadataError::new( + "missing observables or tracked_ops metadata arrays", + )); + } + + Ok(parsed) +} + +fn parse_pecos_metadata_dem_output( + idx: usize, + target: &serde_json::Value, +) -> Result { + let object = target + .as_object() + .ok_or_else(|| PecosDemMetadataError::new(format!("DEM output {idx} is not an object")))?; + + let id = object + .get("id") + .and_then(serde_json::Value::as_u64) + .ok_or_else(|| PecosDemMetadataError::new(format!("DEM output {idx} is missing id")))?; + let id = u32::try_from(id).map_err(|_| { + PecosDemMetadataError::new(format!("DEM output {idx} id does not fit in u32")) + })?; + + let mut dem_output = DemOutput::new(id); + let mut explicit_kind = None; + + if let Some(kind_value) = object.get("kind") { + let kind = kind_value.as_str().ok_or_else(|| { + PecosDemMetadataError::new(format!("DEM output {idx} kind is not a string")) + })?; + if kind != "dem_output" { + let parsed_kind = DemOutputKind::from_metadata_str(kind).ok_or_else(|| { + PecosDemMetadataError::new(format!("DEM output {idx} has unknown kind: {kind}")) + })?; + explicit_kind = Some(parsed_kind); + dem_output = dem_output.with_kind(parsed_kind); + } + } + + if let Some(label_value) = object.get("label") { + if !label_value.is_null() { + let label = label_value.as_str().ok_or_else(|| { + PecosDemMetadataError::new(format!( + "DEM output {idx} label is not a string or null" + )) + })?; + dem_output = dem_output.with_label(label); + } + } + + if let Some(pauli_value) = object.get("pauli") { + if !pauli_value.is_null() { + let pauli = pauli_value.as_str().ok_or_else(|| { + PecosDemMetadataError::new(format!( + "DEM output {idx} pauli is not a string or null" + )) + })?; + let pauli = pauli.parse::().map_err(|err| { + PecosDemMetadataError::new(format!( + "DEM output {idx} has invalid PauliString: {err}" + )) + })?; + dem_output = dem_output.with_pauli(pauli); + } + } + + let records = if let Some(records_value) = object.get("records") { + if records_value.is_null() { + Vec::new() + } else { + let records = records_value.as_array().ok_or_else(|| { + PecosDemMetadataError::new(format!( + "DEM output {idx} records is not an array or null" + )) + })?; + records + .iter() + .enumerate() + .map(|(record_idx, record)| { + let record = record.as_i64().ok_or_else(|| { + PecosDemMetadataError::new(format!( + "DEM output {idx} record {record_idx} is not an integer" + )) + })?; + i32::try_from(record).map_err(|_| { + PecosDemMetadataError::new(format!( + "DEM output {idx} record {record_idx} does not fit in i32" + )) + }) + }) + .collect::, _>>()? + } + } else { + Vec::new() + }; + + if explicit_kind == Some(DemOutputKind::TrackedOperator) && !records.is_empty() { + return Err(PecosDemMetadataError::new(format!( + "tracked operator DEM output {idx} cannot have measurement records" + ))); + } + + if !records.is_empty() || explicit_kind == Some(DemOutputKind::Observable) { + dem_output = dem_output.with_records(records); + } + + Ok(dem_output) +} + +// ============================================================================ +// Detector Error Model +// ============================================================================ + +/// A complete Detector Error Model (DEM). +/// +/// This represents the noise model of a quantum circuit. It maps mechanisms +/// (detector/DEM-output effects) to their probabilities. +/// +/// # Aggregation Modes +/// +/// The DEM supports two modes controlled by `aggregate`: +/// +/// - **Aggregated mode** (`aggregate = true`): Mechanisms with the same effect +/// are combined into a single entry using the independent error formula. +/// This is more compact but loses information about noise sources. +/// +/// - **Non-aggregated mode** (`aggregate = false`, default): Each noise source +/// is kept as a separate entry. This preserves correlation information and +/// allows advanced decoders to understand the noise structure. +/// +/// # Decomposed Entries /// /// In addition to direct mechanisms, the DEM can store "decomposed" entries /// that represent Y faults as X^Z. These are stored separately because: @@ -777,16 +1928,20 @@ impl NoiseConfig { pub struct DetectorErrorModel { /// Detector definitions. pub detectors: Vec, - /// Logical observable definitions. - pub observables: Vec, + /// Measurement-record observables rendered as standard Stim `L` outputs. + pub observables: Vec, + /// PECOS tracked Pauli operators. + /// + /// These have their own ID space and are emitted only as PECOS metadata. + pub tracked_ops: Vec, /// Error contributions with source tracking. /// Each contribution tracks whether it came from a direct (X, Z) or decomposable (Y) source. - contributions: Vec, + contributions: Vec, /// Count of graphlike decomposable sources per 2-detector mechanism. /// Key is (d0, d1) with d0 < d1. A source is "graphlike decomposable" if both /// component effects are non-empty and graphlike (≤2 detectors). /// Used to determine output format: ≥2 → 3 forms, 1 → 2 forms, 0 → 1 form. - graphlike_decomposable_counts: HashMap<(u32, u32), u32>, + graphlike_decomposable_counts: BTreeMap<(u32, u32), u32>, } impl DetectorErrorModel { @@ -796,19 +1951,21 @@ impl DetectorErrorModel { Self { detectors: Vec::new(), observables: Vec::new(), + tracked_ops: Vec::new(), contributions: Vec::new(), - graphlike_decomposable_counts: HashMap::new(), + graphlike_decomposable_counts: BTreeMap::new(), } } /// Creates a DEM with pre-allocated capacity. #[must_use] - pub fn with_capacity(num_detectors: usize, num_observables: usize) -> Self { + pub fn with_capacity(num_detectors: usize, num_dem_outputs: usize) -> Self { Self { detectors: Vec::with_capacity(num_detectors), - observables: Vec::with_capacity(num_observables), + observables: Vec::with_capacity(num_dem_outputs), + tracked_ops: Vec::new(), contributions: Vec::new(), - graphlike_decomposable_counts: HashMap::new(), + graphlike_decomposable_counts: BTreeMap::new(), } } @@ -823,7 +1980,60 @@ impl DetectorErrorModel { #[inline] #[must_use] pub fn num_observables(&self) -> usize { - self.observables.len() + self.observables + .iter() + .map(|op| op.id as usize + 1) + .max() + .unwrap_or(0) + } + + /// Returns the number of standard DEM `L` outputs. + #[inline] + #[must_use] + pub fn num_dem_outputs(&self) -> usize { + self.num_observables() + } + + /// Returns the number of tracked operators. + #[inline] + #[must_use] + pub fn num_tracked_ops(&self) -> usize { + self.tracked_ops + .iter() + .map(|op| op.id as usize + 1) + .max() + .unwrap_or(0) + } + + /// Returns standard DEM output definitions (`L` observables). + #[inline] + #[must_use] + pub fn dem_outputs(&self) -> &[DemOutput] { + &self.observables + } + + /// Returns mutable standard DEM output definitions (`L` observables). + #[inline] + #[must_use] + pub fn dem_outputs_mut(&mut self) -> &mut [DemOutput] { + &mut self.observables + } + + /// Iterates over observables. + pub fn observables(&self) -> impl Iterator { + self.observables.iter() + } + + /// Returns all tracked operator definitions. + #[inline] + #[must_use] + pub fn tracked_ops(&self) -> &[DemOutput] { + &self.tracked_ops + } + + /// Iterates over tracked operators. + pub fn tracked_operators(&self) -> impl Iterator { + self.tracked_ops.iter() } /// Returns the number of tracked contributions. @@ -833,6 +2043,186 @@ impl DetectorErrorModel { self.contributions.len() } + /// Exports PECOS-only metadata that is not representable in standard Stim + /// DEM syntax. + /// + /// The standard DEM string remains decoder-compatible and uses ordinary + /// `logical_observable L` declarations. This JSON form preserves the + /// richer PECOS DEM-output information, including tracked Pauli operators. + #[must_use] + pub fn to_pecos_metadata_json(&self) -> String { + let observables: Vec = self + .observables + .iter() + .map(pecos_metadata_dem_output_value) + .collect(); + let tracked_ops: Vec = self + .tracked_ops + .iter() + .map(pecos_metadata_dem_output_value) + .collect(); + + serde_json::to_string_pretty(&serde_json::json!({ + "format": "pecos.dem.metadata", + "version": 1, + "observables": observables, + "tracked_ops": tracked_ops, + })) + .expect("serializing PECOS DEM metadata should not fail") + } + + /// Applies PECOS DEM metadata JSON to this model. + /// + /// This is the inverse of [`Self::to_pecos_metadata_json`] for DEM output + /// definitions. It updates existing outputs by `id` and adds any that + /// are present in the metadata but missing from the DEM. + /// + /// # Errors + /// + /// Returns an error if the JSON is malformed, uses an unsupported metadata + /// version, has an unknown op kind, or contains invalid Pauli/record + /// fields. + pub fn apply_pecos_metadata_json(&mut self, json: &str) -> Result<(), PecosDemMetadataError> { + let metadata = parse_pecos_metadata_json(json)?; + for observable in metadata.observables { + self.apply_observable_metadata(observable); + } + for tracked_op in metadata.tracked_ops { + self.apply_tracked_op_metadata(tracked_op); + } + Ok(()) + } + + /// Returns a copy of this model with PECOS DEM metadata JSON applied. + /// + /// # Errors + /// + /// See [`Self::apply_pecos_metadata_json`]. + pub fn with_pecos_metadata_json(mut self, json: &str) -> Result { + self.apply_pecos_metadata_json(json)?; + Ok(self) + } + + /// Converts the DEM to PECOS's strict superset of Stim DEM text. + /// + /// The beginning of the output is exactly the standard Stim-compatible DEM + /// from [`Self::to_string`]. PECOS-only metadata follows as + /// `pecos_observable {json}` and `pecos_tracked_op {json}` statements. This makes PECOS DEM text a + /// strict superset: every Stim DEM remains valid PECOS DEM text, and PECOS + /// adds statements for data Stim cannot represent. + #[must_use] + pub fn to_pecos_string(&self) -> String { + let mut text = self.to_string(); + let observable_lines = self + .observables + .iter() + .map(|observable| { + let value = pecos_metadata_dem_output_value(observable); + let payload = serde_json::to_string(&value) + .expect("serializing PECOS observable metadata should not fail"); + format!("pecos_observable {payload}") + }); + let tracked_op_lines = self + .tracked_ops + .iter() + .map(|tracked_op| { + let value = pecos_metadata_dem_output_value(tracked_op); + let payload = serde_json::to_string(&value) + .expect("serializing PECOS tracked-op metadata should not fail"); + format!("pecos_tracked_op {payload}") + }); + let metadata_lines: Vec = observable_lines + .chain(tracked_op_lines) + .collect(); + + if metadata_lines.is_empty() { + return text; + } + if !text.is_empty() { + text.push('\n'); + } + text.push_str(&metadata_lines.join("\n")); + text + } + + /// Applies PECOS metadata embedded in extended DEM text. + /// + /// Stim-compatible lines are ignored by this method. PECOS extension lines + /// are parsed and merged into the observable/tracked-op definitions. + /// + /// # Errors + /// + /// Returns an error if a PECOS metadata line is malformed. + pub fn apply_pecos_dem_metadata( + &mut self, + dem_text: &str, + ) -> Result<(), PecosDemMetadataError> { + for line in dem_text.lines() { + let line = line.trim(); + if line.is_empty() || line.starts_with('#') { + continue; + } + if line.starts_with("pecos_observable") + || line.starts_with("pecos_tracked_op") + { + self.apply_dem_output_metadata(parse_pecos_dem_metadata_line(line)?); + } else if line.starts_with("pecos_") { + return Err(PecosDemMetadataError::new(format!( + "unsupported PECOS DEM extension line: {line}" + ))); + } + } + Ok(()) + } + + /// Returns a copy of this model with PECOS metadata from extended DEM text + /// applied. + /// + /// # Errors + /// + /// See [`Self::apply_pecos_dem_metadata`]. + pub fn with_pecos_dem_metadata( + mut self, + dem_text: &str, + ) -> Result { + self.apply_pecos_dem_metadata(dem_text)?; + Ok(self) + } + + fn apply_dem_output_metadata(&mut self, target: DemOutput) { + if target.is_tracked_operator() { + self.apply_tracked_op_metadata(target); + } else { + self.apply_observable_metadata(target); + } + } + + fn apply_observable_metadata(&mut self, mut target: DemOutput) { + target.kind.get_or_insert(DemOutputKind::Observable); + if let Some(existing) = self + .observables + .iter_mut() + .find(|existing| existing.id == target.id) + { + *existing = target; + } else { + self.add_observable(target); + } + } + + fn apply_tracked_op_metadata(&mut self, mut target: DemOutput) { + target.kind = Some(DemOutputKind::TrackedOperator); + if let Some(existing) = self + .tracked_ops + .iter_mut() + .find(|existing| existing.id == target.id) + { + *existing = target; + } else { + self.add_tracked_operator(target); + } + } + /// Returns debug info about contributions for a specific mechanism. /// /// Format: One line per contribution showing source type and probability. @@ -842,32 +2232,37 @@ impl DetectorErrorModel { let mut lines = Vec::new(); for contrib in &self.contributions { - if contrib.effect.detectors == target_dets && contrib.effect.logicals.is_empty() { + if contrib.effect.detectors == target_dets && contrib.effect.dem_outputs.is_empty() { let source_type = match &contrib.source_type { - ErrorSourceType::Direct => "Direct".to_string(), - ErrorSourceType::YDecomposed { + FaultSourceType::Direct => "Direct".to_string(), + FaultSourceType::DirectOneSidedComponent => { + "DirectOneSidedComponent".to_string() + } + FaultSourceType::YDecomposed { x_detectors, - x_logicals, + x_dem_outputs, z_detectors, - z_logicals, + z_dem_outputs, } => { let x_dets: Vec<_> = x_detectors.iter().map(|d| format!("D{d}")).collect(); let z_dets: Vec<_> = z_detectors.iter().map(|d| format!("D{d}")).collect(); - let x_logs: Vec<_> = x_logicals.iter().map(|l| format!("L{l}")).collect(); - let z_logs: Vec<_> = z_logicals.iter().map(|l| format!("L{l}")).collect(); + let x_outputs: Vec<_> = + x_dem_outputs.iter().map(|l| format!("L{l}")).collect(); + let z_outputs: Vec<_> = + z_dem_outputs.iter().map(|l| format!("L{l}")).collect(); format!( "YDecomposed(X=[{}{}], Z=[{}{}])", x_dets.join(" "), - if x_logs.is_empty() { + if x_outputs.is_empty() { String::new() } else { - format!(" {}", x_logs.join(" ")) + format!(" {}", x_outputs.join(" ")) }, z_dets.join(" "), - if z_logs.is_empty() { + if z_outputs.is_empty() { String::new() } else { - format!(" {}", z_logs.join(" ")) + format!(" {}", z_outputs.join(" ")) } ) } @@ -891,6 +2286,22 @@ impl DetectorErrorModel { } } + /// Returns all contributions matching a full detector/DEM-output effect. + #[must_use] + pub fn contributions_for_effect( + &self, + detectors: &[u32], + dem_outputs: &[u32], + ) -> Vec { + let target = + FaultMechanism::from_unsorted(detectors.iter().copied(), dem_outputs.iter().copied()); + self.contributions + .iter() + .filter(|contrib| contrib.effect == target) + .cloned() + .collect() + } + /// Returns debug info about all unique contribution effects. #[must_use] pub fn all_contribution_effects(&self) -> String { @@ -907,7 +2318,7 @@ impl DetectorErrorModel { .collect(); let log_str: Vec<_> = contrib .effect - .logicals + .dem_outputs .iter() .map(|l| format!("L{l}")) .collect(); @@ -945,18 +2356,275 @@ impl DetectorErrorModel { ) } + /// Returns structured summaries for all unique contribution effects. + #[must_use] + pub fn contribution_effect_summaries(&self) -> Vec { + let mut by_effect: BTreeMap = BTreeMap::new(); + + for contrib in &self.contributions { + let summary = by_effect.entry(contrib.effect.clone()).or_insert_with(|| { + ContributionEffectSummary { + effect: contrib.effect.clone(), + num_contributions: 0, + total_probability: 0.0, + direct_count: 0, + direct_probability: 0.0, + y_decomposed_count: 0, + y_decomposed_probability: 0.0, + graphlike_decomposable_count: 0, + } + }); + + summary.num_contributions += 1; + summary.total_probability += contrib.probability; + match contrib.source_type { + FaultSourceType::Direct | FaultSourceType::DirectOneSidedComponent => { + summary.direct_count += 1; + summary.direct_probability += contrib.probability; + } + FaultSourceType::YDecomposed { .. } => { + summary.y_decomposed_count += 1; + summary.y_decomposed_probability += contrib.probability; + } + } + } + + for summary in by_effect.values_mut() { + if summary.effect.dem_outputs.is_empty() && summary.effect.detectors.len() == 2 { + summary.graphlike_decomposable_count = self.graphlike_decomposable_count( + summary.effect.detectors[0], + summary.effect.detectors[1], + ); + } + } + + by_effect.into_values().collect() + } + + /// Returns structured summaries of contribution render buckets before regrouping. + /// + /// This mirrors the per-contribution render pass used by + /// `to_string_decomposed()`, but keeps the original effect attached so callers + /// can see which source families collapse onto the same rendered targets. + #[must_use] + pub fn contribution_render_summaries(&self) -> Vec { + self.contribution_render_summaries_with_two_detector_direct_policy( + TwoDetectorDirectRenderPolicy::KeepDirect, + ) + } + + /// Returns structured summaries of contribution render buckets before + /// regrouping, using an explicit policy for direct 2-detector rendering. + #[must_use] + pub fn contribution_render_summaries_with_two_detector_direct_policy( + &self, + two_detector_direct_policy: TwoDetectorDirectRenderPolicy, + ) -> Vec { + #[derive(Default)] + struct Accumulator { + num_contributions: usize, + total_probability: f64, + combined_probability: f64, + source_type_counts: BTreeMap, + source_type_probabilities: BTreeMap, + direct_source_family_counts: BTreeMap, + direct_source_family_probabilities: BTreeMap, + } + + fn source_type_label(source_type: &FaultSourceType) -> &'static str { + match source_type { + FaultSourceType::Direct => "Direct", + FaultSourceType::DirectOneSidedComponent => "DirectOneSidedComponent", + FaultSourceType::YDecomposed { .. } => "YDecomposed", + } + } + + fn direct_source_family_label(family: DirectSourceFamily) -> &'static str { + match family { + DirectSourceFamily::SingleLocation => "SingleLocation", + DirectSourceFamily::SingleLocationY => "SingleLocationY", + DirectSourceFamily::TwoLocationPlainY => "TwoLocationPlainY", + DirectSourceFamily::TwoLocationComponent => "TwoLocationComponent", + DirectSourceFamily::TwoLocationOneSidedComponent => "TwoLocationOneSidedComponent", + DirectSourceFamily::Other => "Other", + } + } + + let graphlike_set = self.collect_graphlike_mechanisms(); + let graphlike_index = GraphlikeDecompositionIndex::new(&graphlike_set); + let mut rendered_targets_cache: BTreeMap<(FaultMechanism, FaultSourceType), String> = + BTreeMap::new(); + let mut by_render: BTreeMap<(FaultMechanism, String), Accumulator> = BTreeMap::new(); + + for contrib in &self.contributions { + if contrib.effect.is_empty() || contrib.probability <= 0.0 { + continue; + } + + let rendered_targets = Self::contribution_targets( + contrib, + &graphlike_index, + None, + two_detector_direct_policy, + &mut rendered_targets_cache, + ); + let acc = by_render + .entry((contrib.effect.clone(), rendered_targets)) + .or_default(); + acc.num_contributions += 1; + acc.total_probability += contrib.probability; + acc.combined_probability = + combine_independent_probs(acc.combined_probability, contrib.probability); + + let source_label = source_type_label(&contrib.source_type).to_string(); + *acc.source_type_counts + .entry(source_label.clone()) + .or_insert(0) += 1; + *acc.source_type_probabilities + .entry(source_label) + .or_insert(0.0) += contrib.probability; + + if let Some(family) = contrib.direct_source_family { + let family_label = direct_source_family_label(family).to_string(); + *acc.direct_source_family_counts + .entry(family_label.clone()) + .or_insert(0) += 1; + *acc.direct_source_family_probabilities + .entry(family_label) + .or_insert(0.0) += contrib.probability; + } + } + + by_render + .into_iter() + .map( + |((effect, rendered_targets), acc)| ContributionRenderSummary { + effect, + rendered_targets, + num_contributions: acc.num_contributions, + total_probability: acc.total_probability, + combined_probability: acc.combined_probability, + source_type_counts: acc.source_type_counts, + source_type_probabilities: acc.source_type_probabilities, + direct_source_family_counts: acc.direct_source_family_counts, + direct_source_family_probabilities: acc.direct_source_family_probabilities, + }, + ) + .collect() + } + + /// Returns per-contribution render records before final regrouping. + /// + /// This mirrors the same contribution render pass used by + /// `to_string_decomposed()`, but keeps one output row per tracked + /// contribution instead of aggregating by `(effect, rendered_targets)`. + #[must_use] + pub fn contribution_render_records(&self) -> Vec { + self.contribution_render_records_with_two_detector_direct_policy( + TwoDetectorDirectRenderPolicy::KeepDirect, + ) + } + + /// Returns per-contribution render records before final regrouping, using + /// an explicit policy for direct 2-detector rendering. + #[must_use] + pub fn contribution_render_records_with_two_detector_direct_policy( + &self, + two_detector_direct_policy: TwoDetectorDirectRenderPolicy, + ) -> Vec { + let graphlike_set = self.collect_graphlike_mechanisms(); + let graphlike_index = GraphlikeDecompositionIndex::new(&graphlike_set); + let mut rendered_targets_cache: BTreeMap<(FaultMechanism, FaultSourceType), String> = + BTreeMap::new(); + let mut records = Vec::new(); + + for contrib in &self.contributions { + if contrib.effect.is_empty() || contrib.probability <= 0.0 { + continue; + } + + let (rendered_targets, render_strategy, recorded_component_targets) = + Self::contribution_render_details( + contrib, + &graphlike_index, + None, + two_detector_direct_policy, + &mut rendered_targets_cache, + ); + records.push(ContributionRenderRecord { + rendered_targets, + render_strategy, + recorded_component_targets, + contribution: contrib.clone(), + }); + } + + records + } + /// Adds a direct error contribution (X or Z channel). /// /// Direct contributions are output as direct forms (e.g., "D0 D1") rather than /// decomposed forms. Use this for X and Z error channels. /// /// Requires source tracking to be enabled. - pub fn add_direct_contribution(&mut self, effect: ErrorMechanism, probability: f64) { + pub fn add_direct_contribution(&mut self, effect: FaultMechanism, probability: f64) { + if effect.is_empty() || probability <= 0.0 { + return; + } + self.contributions + .push(FaultContribution::direct(effect, probability)); + } + + /// Adds a direct error contribution with source metadata. + pub(crate) fn add_direct_contribution_with_source( + &mut self, + effect: FaultMechanism, + probability: f64, + source: SourceMetadata<'_, usize>, + ) { if effect.is_empty() || probability <= 0.0 { return; } + let location_indices = convert_location_indices(source.location_indices); self.contributions - .push(ErrorContribution::direct(effect, probability)); + .push(FaultContribution::direct_with_source( + effect, + probability, + SourceMetadata::new( + &location_indices, + source.paulis, + source.gate_types, + source.before_flags, + ), + )); + } + + /// Adds a direct error contribution with source metadata and per-location + /// component effects. + pub(crate) fn add_direct_contribution_with_source_components( + &mut self, + effect: FaultMechanism, + probability: f64, + source: SourceMetadata<'_, usize>, + components: DirectSourceComponents<'_>, + ) { + if effect.is_empty() || probability <= 0.0 { + return; + } + let location_indices = convert_location_indices(source.location_indices); + self.contributions + .push(FaultContribution::direct_with_source_components( + effect, + probability, + SourceMetadata::new( + &location_indices, + source.paulis, + source.gate_types, + source.before_flags, + ), + components, + )); } /// Adds a Y-decomposed error contribution. @@ -968,8 +2636,8 @@ impl DetectorErrorModel { /// Requires source tracking to be enabled. pub fn add_y_decomposed_contribution( &mut self, - x_effect: &ErrorMechanism, - z_effect: &ErrorMechanism, + x_effect: &FaultMechanism, + z_effect: &FaultMechanism, probability: f64, ) { if probability <= 0.0 { @@ -988,14 +2656,59 @@ impl DetectorErrorModel { return; } - // Always record as YDecomposed since the source is a Y-containing channel. - // The distinction between Direct and YDecomposed affects output form selection. - self.contributions.push(ErrorContribution::y_decomposed( - combined, - x_effect, - z_effect, - probability, - )); + // If one branch is empty, the Y-containing source has the same net effect as + // the non-empty branch and should be tracked as a direct source. + if x_effect.is_empty() || z_effect.is_empty() { + self.add_direct_contribution(combined, probability); + return; + } + + // Otherwise record as YDecomposed. The distinction between Direct and + // YDecomposed affects output form selection. + self.contributions.push(FaultContribution::y_decomposed( + combined, + x_effect, + z_effect, + probability, + )); + } + + /// Adds a Y-decomposed error contribution with source metadata. + pub(crate) fn add_y_decomposed_contribution_with_source( + &mut self, + x_effect: &FaultMechanism, + z_effect: &FaultMechanism, + probability: f64, + source: SourceMetadata<'_, usize>, + ) { + if probability <= 0.0 { + return; + } + + let combined = x_effect.xor(z_effect); + if combined.is_empty() { + return; + } + + if x_effect.is_empty() || z_effect.is_empty() { + self.add_direct_contribution_with_source(combined, probability, source); + return; + } + + let location_indices = convert_location_indices(source.location_indices); + self.contributions + .push(FaultContribution::y_decomposed_with_source( + combined, + x_effect, + z_effect, + probability, + SourceMetadata::new( + &location_indices, + source.paulis, + source.gate_types, + source.before_flags, + ), + )); } /// Marks a 2-detector mechanism as having a graphlike decomposable source. @@ -1009,11 +2722,51 @@ impl DetectorErrorModel { /// /// This should be called from the builder when processing 2-qubit gate channels /// where both component effects are graphlike. + /// Returns grouped mechanisms as (probability, `detector_ids`, `observable_ids`) tuples. + /// + /// Combines contributions with the same effect using the XOR probability formula. + /// Also returns detector coordinate map. This is the structured equivalent of + /// `to_string()` — same data, no string intermediary. + #[must_use] + pub fn to_mechanisms(&self) -> (Vec<(f64, Vec, Vec)>, Vec<(u32, Vec)>) { + // Group contributions by effect + let mut by_effect: BTreeMap = BTreeMap::new(); + for contrib in &self.contributions { + by_effect + .entry(contrib.effect.clone()) + .and_modify(|p| *p = combine_independent_probs(*p, contrib.probability)) + .or_insert(contrib.probability); + } + + let mechanisms: Vec<(f64, Vec, Vec)> = by_effect + .into_iter() + .filter(|(effect, prob)| !effect.is_empty() && *prob > 0.0) + .map(|(effect, prob)| (prob, effect.detectors.to_vec(), effect.dem_outputs.to_vec())) + .collect(); + + let coords: Vec<(u32, Vec)> = self + .detectors + .iter() + .filter_map(|det| det.coords.map(|[x, y, z]| (det.id, vec![x, y, z]))) + .collect(); + + (mechanisms, coords) + } + pub fn mark_graphlike_decomposable(&mut self, d0: u32, d1: u32) { let key = if d0 < d1 { (d0, d1) } else { (d1, d0) }; *self.graphlike_decomposable_counts.entry(key).or_insert(0) += 1; } + /// Merge contributions and graphlike counts from another DEM. + /// Used for parallelized DEM construction. + pub fn merge_contributions_from(&mut self, other: Self) { + self.contributions.extend(other.contributions); + for (key, count) in other.graphlike_decomposable_counts { + *self.graphlike_decomposable_counts.entry(key).or_insert(0) += count; + } + } + /// Returns the number of graphlike decomposable sources for a 2-detector mechanism. #[must_use] pub fn graphlike_decomposable_count(&self, d0: u32, d1: u32) -> u32 { @@ -1029,14 +2782,33 @@ impl DetectorErrorModel { self.detectors.push(detector); } - /// Adds a logical observable definition. - pub fn add_observable(&mut self, observable: LogicalObservable) { + /// Adds a non-detector DEM output definition. + /// + /// Observables are stored in the standard `L` namespace. Tracked + /// operators are stored in PECOS metadata with a separate ID space. + pub fn add_dem_output(&mut self, output: DemOutput) { + if output.is_tracked_operator() { + self.add_tracked_operator(output); + } else { + self.add_observable(output); + } + } + + /// Adds a standard Stim observable (`L`) definition. + pub fn add_observable(&mut self, mut observable: DemOutput) { + observable.kind.get_or_insert(DemOutputKind::Observable); self.observables.push(observable); } + /// Adds a PECOS tracked operator definition. + pub fn add_tracked_operator(&mut self, mut tracked_op: DemOutput) { + tracked_op.kind = Some(DemOutputKind::TrackedOperator); + self.tracked_ops.push(tracked_op); + } + /// Converts the DEM to a string in standard DEM format. /// - /// Each error mechanism is output with its total probability, with no + /// Each fault mechanism is output with its total probability, with no /// splitting into decomposed forms. This matches Stim's /// `detector_error_model(decompose_errors=False)` output. /// @@ -1056,14 +2828,14 @@ impl DetectorErrorModel { } } - // Add logical observable annotations + // Add standard observable annotations for obs in &self.observables { lines.push(format!("logical_observable L{}", obs.id)); } // Group contributions by effect, combining probabilities using XOR formula // (errors toggle detector bits, so two errors on same detector cancel) - let mut by_effect: BTreeMap = BTreeMap::new(); + let mut by_effect: BTreeMap = BTreeMap::new(); for contrib in &self.contributions { by_effect .entry(contrib.effect.clone()) @@ -1090,698 +2862,418 @@ impl DetectorErrorModel { lines.join("\n") } - /// Converts the DEM to Stim format using source tracking (decomposed format). - /// - /// This matches Stim's `detector_error_model(decompose_errors=True)` output. - /// Error mechanisms are split into direct and decomposed forms based on - /// their source types (X/Z vs Y errors). - /// - /// For each unique detector effect: - /// - Sum probabilities from direct sources (X, Z) -> output as direct form - /// - Y-decomposed sources -> output as decomposed form (X ^ Z) - /// - /// Converts the DEM to a string with decomposed representations. - /// - /// Requires source tracking to be enabled and contributions to be populated. - /// - /// For 2-detector mechanisms Di Dj: - /// - If both Di L0 and Dj L0 exist as mechanisms, outputs both direct form - /// and L0 cancellation form (Di L0 ^ Dj L0), with probability split based - /// on relative mechanism probabilities. - /// - Otherwise, outputs decomposed forms (Di ^ Dj, Dj ^ Di) with probability split. - /// - /// This provides representation diversity for decoders, similar to Stim's - /// `decompose_errors=True` behavior. - #[must_use] - pub fn to_string_decomposed(&self) -> String { - let mut lines = Vec::new(); - - // Add detector coordinate annotations - for det in &self.detectors { - if let Some([x, y, z]) = det.coords { - lines.push(format!("detector({x}, {y}, {z}) D{}", det.id)); - } else { - lines.push(format!("detector D{}", det.id)); - } - } + fn collect_singleton_index(&self) -> SingletonDecompositionIndex { + SingletonDecompositionIndex::from_contributions(&self.contributions) + } - // Add logical observable annotations - for obs in &self.observables { - lines.push(format!("logical_observable L{}", obs.id)); - } + fn maximally_decompose_graphlike_effect( + effect: &FaultMechanism, + singleton_set: &SingletonDecompositionIndex, + ) -> Vec { + find_singleton_decomposition(effect, singleton_set) + .filter(|parts| !parts.is_empty()) + .unwrap_or_else(|| vec![effect.clone()]) + } - // Find standalone detectors from contributions - let mut standalone_detectors: std::collections::HashSet = - std::collections::HashSet::new(); - for contrib in &self.contributions { - if contrib.effect.num_detectors() == 1 && contrib.effect.logicals.is_empty() { - standalone_detectors.insert(contrib.effect.detectors[0]); - } - } + fn maybe_maximally_decompose_parts( + parts: Vec, + singleton_set: Option<&SingletonDecompositionIndex>, + ) -> Vec { + let Some(singleton_set) = singleton_set else { + return parts; + }; - // Find single-detector + L0 mechanisms (Di L0) and their probabilities - // These can be used for L0 cancellation decomposition - let mut det_l0_probs: HashMap = HashMap::new(); - for contrib in &self.contributions { - if contrib.effect.num_detectors() == 1 - && contrib.effect.logicals.len() == 1 - && contrib.effect.logicals[0] == 0 - { - let det_id = contrib.effect.detectors[0]; - det_l0_probs - .entry(det_id) - .and_modify(|p| *p = combine_independent_probs(*p, contrib.probability)) - .or_insert(contrib.probability); + let mut out = Vec::new(); + for part in parts { + if part.is_graphlike() { + out.extend(Self::maximally_decompose_graphlike_effect( + &part, + singleton_set, + )); + } else { + out.push(part); } } + out + } - // Group contributions by effect, combining probabilities using independent error formula - // p_combined = p1 + p2 - p1*p2 = 1 - (1-p1)*(1-p2) - let mut by_effect: BTreeMap = BTreeMap::new(); - for contrib in &self.contributions { - by_effect - .entry(contrib.effect.clone()) - .and_modify(|p| *p = combine_independent_probs(*p, contrib.probability)) - .or_insert(contrib.probability); + fn recorded_component_targets( + contrib: &FaultContribution, + singleton_set: Option<&SingletonDecompositionIndex>, + ) -> Option { + let (first, second) = contrib.direct_component_effects()?; + let targets = Self::maybe_maximally_decompose_parts( + [first, second] + .into_iter() + .filter(|part| !part.is_empty()) + .collect(), + singleton_set, + ) + .iter() + .map(format_mechanism_targets) + .filter(|targets| !targets.is_empty()) + .collect::>() + .join(" ^ "); + if targets.is_empty() { + None + } else { + Some(targets) } + } - // Process each unique effect - for (effect, total_prob) in &by_effect { - if effect.is_empty() || *total_prob <= 0.0 { - continue; - } + fn two_detector_direct_targets( + effect: &FaultMechanism, + singleton_set: Option<&SingletonDecompositionIndex>, + ) -> String { + Self::maybe_maximally_decompose_parts(vec![effect.clone()], singleton_set) + .iter() + .map(format_mechanism_targets) + .collect::>() + .join(" ^ ") + } - // Check if this is a 2-detector mechanism with no logicals - let is_2det_no_logical = effect.num_detectors() == 2 && effect.logicals.is_empty(); - - if is_2det_no_logical { - let d0 = effect.detectors[0]; - let d1 = effect.detectors[1]; - - // Check if L0 cancellation decomposition is possible - // (both Di L0 and Dj L0 exist as mechanisms) - let has_d0_l0 = det_l0_probs.contains_key(&d0); - let has_d1_l0 = det_l0_probs.contains_key(&d1); - - if has_d0_l0 && has_d1_l0 { - // L0 cancellation is possible: Di Dj can be represented as Di L0 ^ Dj L0 - // Split probability between direct form and L0 cancellation form - // - // Heuristic: Use approximately 25% for L0 cancellation form, which - // matches the average ratio observed in Stim's decomposed output. - // The exact split varies in Stim (10-50%), but 25% is a reasonable - // approximation for decoder compatibility. - let l0_fraction = 0.25; - let direct_fraction = 1.0 - l0_fraction; - - let direct_prob = total_prob * direct_fraction; - let l0_prob = total_prob * l0_fraction; - - // Direct form - if direct_prob > 0.0 { - lines.push(format!( - "error({}) D{} D{}", - format_probability(direct_prob), - d0, - d1 - )); - } + fn contribution_render_details( + contrib: &FaultContribution, + graphlike_index: &GraphlikeDecompositionIndex, + singleton_set: Option<&SingletonDecompositionIndex>, + two_detector_direct_policy: TwoDetectorDirectRenderPolicy, + cache: &mut BTreeMap<(FaultMechanism, FaultSourceType), String>, + ) -> (String, ContributionRenderStrategy, Option) { + let recorded_component_targets = Self::recorded_component_targets(contrib, singleton_set); + let key = (contrib.effect.clone(), contrib.source_type.clone()); + if let Some(cached) = cache.get(&key) { + let strategy = if contrib.decomposition_components().is_some() { + ContributionRenderStrategy::SourceComponents + } else if contrib.effect.num_detectors() == 2 && contrib.effect.dem_outputs.is_empty() { + let direct_targets = + Self::two_detector_direct_targets(&contrib.effect, singleton_set); + if matches!( + two_detector_direct_policy, + TwoDetectorDirectRenderPolicy::PreferRecordedComponents + ) && recorded_component_targets.as_deref() == Some(cached.as_str()) + && cached != &direct_targets + { + ContributionRenderStrategy::RecordedComponents + } else { + ContributionRenderStrategy::TwoDetectorDirect + } + } else if contrib.effect.is_hyperedge() { + ContributionRenderStrategy::HyperedgeGraphlike + } else { + ContributionRenderStrategy::EffectDirect + }; + return (cached.clone(), strategy, recorded_component_targets); + } - // L0 cancellation form - if l0_prob > 0.0 { - lines.push(format!( - "error({}) D{} L0 ^ D{} L0", - format_probability(l0_prob), - d0, - d1 - )); - } - } else if standalone_detectors.contains(&d0) && standalone_detectors.contains(&d1) { - // Both detectors have standalone mechanisms - use compact decomposition - // (matching Stim's approach of minimal entries) - let graphlike_count = self.graphlike_decomposable_count(d0, d1); - - if graphlike_count >= 2 { - // Direct form only - both detectors flip together - lines.push(format!( - "error({}) D{} D{}", - format_probability(*total_prob), - d0, - d1 - )); + let effect = &contrib.effect; + let (targets, strategy) = if let Some((x_effect, z_effect)) = + contrib.decomposition_components() + { + let x_graphlike = x_effect.is_empty() || x_effect.is_graphlike(); + let z_graphlike = z_effect.is_empty() || z_effect.is_graphlike(); + + if !x_effect.is_empty() && !z_effect.is_empty() && x_graphlike && z_graphlike { + let x_parts = + Self::maybe_maximally_decompose_parts(vec![x_effect.clone()], singleton_set); + let z_parts = + Self::maybe_maximally_decompose_parts(vec![z_effect.clone()], singleton_set); + let targets = x_parts + .iter() + .chain(z_parts.iter()) + .map(format_mechanism_targets) + .filter(|targets| !targets.is_empty()) + .collect::>() + .join(" ^ "); + let targets = if targets.is_empty() { + String::new() + } else { + targets + }; + (targets, ContributionRenderStrategy::SourceComponents) + } else if effect.num_detectors() == 2 && effect.dem_outputs.is_empty() { + let direct_targets = Self::two_detector_direct_targets(effect, singleton_set); + if matches!( + two_detector_direct_policy, + TwoDetectorDirectRenderPolicy::PreferRecordedComponents + ) { + if let Some(component_targets) = recorded_component_targets.as_ref() { + if component_targets == &direct_targets { + ( + direct_targets, + ContributionRenderStrategy::TwoDetectorDirect, + ) + } else { + ( + component_targets.clone(), + ContributionRenderStrategy::RecordedComponents, + ) + } } else { - // Decomposed form - one ordering only - lines.push(format!( - "error({}) D{} ^ D{}", - format_probability(*total_prob), - d0, - d1 - )); + ( + direct_targets, + ContributionRenderStrategy::TwoDetectorDirect, + ) } } else { - // Neither L0 cancellation nor standalone decomposition possible - // Output as direct form - lines.push(format!( - "error({}) D{} D{}", - format_probability(*total_prob), - d0, - d1 - )); + ( + direct_targets, + ContributionRenderStrategy::TwoDetectorDirect, + ) } } else if effect.is_hyperedge() { - // Hyperedge (3+ detectors or 2+ logicals): try to decompose - let graphlike_set = self.collect_graphlike_mechanisms(); - let decompositions = find_hyperedge_decompositions(effect, &graphlike_set); - - if decompositions.is_empty() { - // No valid decomposition found - output as direct form - let targets = format_mechanism_targets(effect); - if !targets.is_empty() { - lines.push(format!( - "error({}) {}", - format_probability(*total_prob), - targets - )); - } - } else { - // Split probability across decompositions - #[allow(clippy::cast_precision_loss)] - let split_prob = *total_prob / decompositions.len() as f64; - for decomp in decompositions { - let targets = decomp + if let Some(decomp) = graphlike_index.find_hyperedge_decomposition(effect) { + ( + Self::maybe_maximally_decompose_parts(decomp, singleton_set) .iter() .map(format_mechanism_targets) .collect::>() - .join(" ^ "); - lines.push(format!( - "error({}) {}", - format_probability(split_prob), - targets - )); - } + .join(" ^ "), + ContributionRenderStrategy::HyperedgeGraphlike, + ) + } else { + ( + format_mechanism_targets(effect), + ContributionRenderStrategy::EffectDirect, + ) } - } else if effect.num_detectors() == 2 && effect.num_logicals() == 1 { - // 2-detector + 1-logical mechanism: try to decompose as D_i ^ D_j L_k - // This matches Stim's behavior of decomposing these into components - let graphlike_set = self.collect_graphlike_mechanisms(); - - let d0 = effect.detectors[0]; - let d1 = effect.detectors[1]; - let l0 = effect.logicals[0]; - - // Try decomposition: D0 ^ (D1 L0) or D1 ^ (D0 L0) - let comp_d0 = ErrorMechanism::from_unsorted([d0], std::iter::empty()); - let comp_d1_l0 = ErrorMechanism::from_unsorted([d1], [l0]); - let comp_d1 = ErrorMechanism::from_unsorted([d1], std::iter::empty()); - let comp_d0_l0 = ErrorMechanism::from_unsorted([d0], [l0]); - - let can_decompose_1 = - graphlike_set.contains(&comp_d0) && graphlike_set.contains(&comp_d1_l0); - let can_decompose_2 = - graphlike_set.contains(&comp_d1) && graphlike_set.contains(&comp_d0_l0); - - if can_decompose_1 || can_decompose_2 { - // Output decomposed form - if can_decompose_1 { - lines.push(format!( - "error({}) D{} ^ D{} L{}", - format_probability(*total_prob), - d0, - d1, - l0 - )); + } else { + ( + Self::maybe_maximally_decompose_parts(vec![effect.clone()], singleton_set) + .iter() + .map(format_mechanism_targets) + .collect::>() + .join(" ^ "), + ContributionRenderStrategy::EffectDirect, + ) + } + } else if effect.num_detectors() == 2 && effect.dem_outputs.is_empty() { + let direct_targets = Self::two_detector_direct_targets(effect, singleton_set); + if matches!( + two_detector_direct_policy, + TwoDetectorDirectRenderPolicy::PreferRecordedComponents + ) { + if let Some(component_targets) = recorded_component_targets.as_ref() { + if component_targets == &direct_targets { + ( + direct_targets, + ContributionRenderStrategy::TwoDetectorDirect, + ) } else { - lines.push(format!( - "error({}) D{} ^ D{} L{}", - format_probability(*total_prob), - d1, - d0, - l0 - )); + ( + component_targets.clone(), + ContributionRenderStrategy::RecordedComponents, + ) } } else { - // Can't decompose - output as direct form - let targets = format_mechanism_targets(effect); - if !targets.is_empty() { - lines.push(format!( - "error({}) {}", - format_probability(*total_prob), - targets - )); - } + ( + direct_targets, + ContributionRenderStrategy::TwoDetectorDirect, + ) } } else { - // Other graphlike mechanism - output as direct form - let targets = format_mechanism_targets(effect); - if !targets.is_empty() { - lines.push(format!( - "error({}) {}", - format_probability(*total_prob), - targets - )); - } + ( + direct_targets, + ContributionRenderStrategy::TwoDetectorDirect, + ) } - } - - lines.join("\n") - } - - /// Collects all graphlike mechanisms from contributions. - /// - /// Returns a set of mechanisms with ≤2 detectors and ≤1 logical, - /// which can be used as components for hyperedge decomposition. - fn collect_graphlike_mechanisms(&self) -> HashSet { - let mut graphlike = HashSet::new(); - for contrib in &self.contributions { - if contrib.effect.is_graphlike() { - graphlike.insert(contrib.effect.clone()); + } else if effect.is_hyperedge() { + if let Some(decomp) = graphlike_index.find_hyperedge_decomposition(effect) { + ( + Self::maybe_maximally_decompose_parts(decomp, singleton_set) + .iter() + .map(format_mechanism_targets) + .collect::>() + .join(" ^ "), + ContributionRenderStrategy::HyperedgeGraphlike, + ) + } else { + ( + format_mechanism_targets(effect), + ContributionRenderStrategy::EffectDirect, + ) } - } - graphlike - } -} - -impl Default for DetectorErrorModel { - fn default() -> Self { - Self::new() - } -} - -// ============================================================================ -// Measurement Noise Model (MNM) -// ============================================================================ - -/// A measurement error mechanism: a set of measurements that flip together. -/// -/// Unlike [`ErrorMechanism`] which operates on detectors, this operates directly -/// on raw measurement indices. This is useful for sampling measurement outcomes -/// without needing detector definitions. -/// -/// Measurements are stored in sorted order for canonical representation. -#[derive(Clone, Default)] -pub struct MeasurementMechanism { - /// Measurement indices that flip together (sorted). - pub measurements: SmallVec<[u32; 4]>, -} - -impl MeasurementMechanism { - /// Creates a new empty measurement mechanism. - #[must_use] - pub fn new() -> Self { - Self::default() - } - - /// Creates a mechanism from unsorted measurement indices. - #[must_use] - pub fn from_unsorted(measurements: impl IntoIterator) -> Self { - let mut meas: SmallVec<[u32; 4]> = measurements.into_iter().collect(); - meas.sort_unstable(); - Self { measurements: meas } - } - - /// Creates a mechanism from pre-sorted measurement indices. - #[must_use] - pub fn from_sorted(measurements: SmallVec<[u32; 4]>) -> Self { - debug_assert!( - measurements.windows(2).all(|w| w[0] <= w[1]), - "measurements must be sorted" - ); - Self { measurements } - } - - /// Returns true if this mechanism has no effect (empty). - #[inline] - #[must_use] - pub fn is_empty(&self) -> bool { - self.measurements.is_empty() - } - - /// Returns the number of measurements in this mechanism. - #[inline] - #[must_use] - pub fn len(&self) -> usize { - self.measurements.len() - } -} - -impl PartialEq for MeasurementMechanism { - fn eq(&self, other: &Self) -> bool { - self.measurements == other.measurements - } -} - -impl Eq for MeasurementMechanism {} - -impl Hash for MeasurementMechanism { - fn hash(&self, state: &mut H) { - self.measurements.hash(state); - } -} - -impl PartialOrd for MeasurementMechanism { - fn partial_cmp(&self, other: &Self) -> Option { - Some(self.cmp(other)) - } -} + } else { + ( + Self::maybe_maximally_decompose_parts(vec![effect.clone()], singleton_set) + .iter() + .map(format_mechanism_targets) + .collect::>() + .join(" ^ "), + ContributionRenderStrategy::EffectDirect, + ) + }; -impl Ord for MeasurementMechanism { - fn cmp(&self, other: &Self) -> Ordering { - self.measurements.cmp(&other.measurements) + cache.insert(key, targets.clone()); + (targets, strategy, recorded_component_targets) } -} -impl fmt::Debug for MeasurementMechanism { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - write!( - f, - "MeasurementMechanism({:?})", - self.measurements.as_slice() + fn contribution_targets( + contrib: &FaultContribution, + graphlike_index: &GraphlikeDecompositionIndex, + singleton_set: Option<&SingletonDecompositionIndex>, + two_detector_direct_policy: TwoDetectorDirectRenderPolicy, + cache: &mut BTreeMap<(FaultMechanism, FaultSourceType), String>, + ) -> String { + Self::contribution_render_details( + contrib, + graphlike_index, + singleton_set, + two_detector_direct_policy, + cache, ) - } -} - -/// A Measurement Noise Model (MNM) for fast approximate sampling. -/// -/// Unlike a DEM which maps error mechanisms to detector effects, the MNM maps -/// directly to measurement effects. This allows sampling raw measurement outcomes -/// without needing detector definitions. -/// -/// # Sampling Modes -/// -/// - **Per-fault-location** (accurate): Sample each (location, Pauli) independently -/// - **Per-mechanism** (fast, approximate): Sample each unique measurement effect once -/// -/// The MNM enables the fast per-mechanism mode while still producing raw measurement -/// outcomes that can be converted to detection events using any detector definition. -/// -/// # Example -/// -/// ``` -/// use pecos_qec::fault_tolerance::DagFaultAnalyzer; -/// use pecos_qec::fault_tolerance::dem_builder::MemBuilder; -/// use pecos_quantum::DagCircuit; -/// use rand::SeedableRng; -/// use rand::rngs::SmallRng; -/// -/// let mut dag = DagCircuit::new(); -/// dag.pz(&[2]); -/// dag.cx(&[(0, 2)]); -/// dag.mz(&[2]); -/// -/// let analyzer = DagFaultAnalyzer::new(&dag); -/// let influence_map = analyzer.build_influence_map(); -/// -/// let mnm = MemBuilder::new(&influence_map) -/// .with_noise(0.01, 0.01, 0.01, 0.01) -/// .build(); -/// -/// // Sample measurement outcomes -/// let mut rng = SmallRng::seed_from_u64(42); -/// let mut outcomes = vec![false; mnm.num_measurements]; -/// mnm.sample_into(&mut outcomes, &mut rng); -/// ``` -#[derive(Debug, Clone, Default)] -pub struct MeasurementNoiseModel { - /// Error mechanisms mapped to their probabilities. - /// Uses `BTreeMap` for deterministic iteration order. - pub mechanisms: BTreeMap, - /// Total number of measurements in the circuit. - pub num_measurements: usize, - /// Optional mapping from influence map index to `TickCircuit` index. - /// If set, outcomes are reordered before detection event conversion. - /// `im_to_tc`[`im_idx`] = `tc_idx` - pub im_to_tc_order: Option>, -} - -impl MeasurementNoiseModel { - /// Creates a new empty MNM. - #[must_use] - pub fn new(num_measurements: usize) -> Self { - Self { - mechanisms: BTreeMap::new(), - num_measurements, - im_to_tc_order: None, - } - } - - /// Sets the measurement order mapping from influence map to `TickCircuit` order. - /// - /// This is needed when detector definitions use `TickCircuit` measurement indices - /// but the influence map uses a different ordering. - /// - /// # Arguments - /// - /// * `im_to_tc` - Mapping where `im_to_tc[im_idx] = tc_idx` - #[must_use] - pub fn with_measurement_order(mut self, im_to_tc: Vec) -> Self { - self.im_to_tc_order = Some(im_to_tc); - self - } - - /// Sets the measurement order mapping (mutable version). - pub fn set_measurement_order(&mut self, im_to_tc: Vec) { - self.im_to_tc_order = Some(im_to_tc); - } - - /// Returns the number of distinct mechanisms. - #[inline] - #[must_use] - pub fn num_mechanisms(&self) -> usize { - self.mechanisms.len() - } - - /// Adds an error mechanism with the given probability. - /// - /// If the mechanism already exists, probabilities are combined - /// using the independent error formula: p1*(1-p2) + p2*(1-p1). - pub fn add_mechanism(&mut self, mechanism: MeasurementMechanism, probability: f64) { - if mechanism.is_empty() || probability <= 0.0 { - return; - } - - self.mechanisms - .entry(mechanism) - .and_modify(|p| *p = combine_probabilities(*p, probability)) - .or_insert(probability); - } - - /// Samples measurement outcomes into the provided buffer. - /// - /// Each mechanism is sampled once according to its probability. - /// When a mechanism fires, its measurements are XOR'd into the outcomes. - /// - /// # Arguments - /// - /// * `outcomes` - Buffer to store measurement outcomes (must be pre-sized) - /// * `rng` - Random number generator - pub fn sample_into(&self, outcomes: &mut [bool], rng: &mut R) { - // Clear outcomes - outcomes.fill(false); - - for (mechanism, &prob) in &self.mechanisms { - if rng.random::() < prob { - for &meas_idx in &mechanism.measurements { - if (meas_idx as usize) < outcomes.len() { - outcomes[meas_idx as usize] ^= true; - } - } - } - } - } - - /// Samples and returns measurement outcomes as a vector. - #[must_use] - pub fn sample(&self, rng: &mut R) -> Vec { - let mut outcomes = vec![false; self.num_measurements]; - self.sample_into(&mut outcomes, rng); - outcomes - } - - /// Iterates over all mechanisms and their probabilities. - pub fn iter(&self) -> impl Iterator { - self.mechanisms.iter() + .0 } - /// Converts measurement outcomes to detection events. + /// Converts the DEM to Stim format using source tracking (decomposed format). /// - /// Given raw measurement outcomes and detector definitions (as measurement indices), - /// computes which detectors fire by XOR'ing the specified measurements for each detector. + /// This matches Stim's `detector_error_model(decompose_errors=True)` output. + /// Fault mechanisms are split into direct and decomposed forms based on + /// their source types (X/Z vs Y errors). /// - /// If `im_to_tc_order` is set, outcomes are first reordered from influence map - /// order to `TickCircuit` order before applying detector records. + /// For each unique detector effect: + /// - Sum probabilities from direct sources (X, Z) -> output as direct form + /// - Y-decomposed sources -> output as decomposed form (X ^ Z) /// - /// # Arguments + /// Converts the DEM to a string with decomposed representations. /// - /// * `outcomes` - Raw measurement outcomes in influence map order (from `sample()`) - /// * `detector_records` - For each detector, the list of measurement indices to XOR. - /// Indices can be negative (offset from end) or positive (absolute). - /// These indices refer to `TickCircuit` measurement order. + /// Requires source tracking to be enabled and contributions to be populated. /// - /// # Returns + /// For 2-detector mechanisms Di Dj: + /// - Output the direct graphlike form `Di Dj`. + /// - Avoid introducing synthetic `Di L0 ^ Dj L0` cancellation variants, + /// because the edge is already graphlike and extra L0 terms can change + /// decoder behavior without adding new information. /// - /// Vector of detection events (true = detector fired) + /// Hyperedges (3+ detectors) are decomposed into graphlike forms when + /// possible. Mechanisms with up to 2 detectors are already graphlike even + /// when they carry multiple DEM outputs. #[must_use] - pub fn compute_detection_events( + fn to_string_decomposed_inner( &self, - outcomes: &[bool], - detector_records: &[Vec], - ) -> Vec { - // Reorder outcomes from IM order to TC order if mapping is set - let tc_outcomes: Vec = if let Some(ref im_to_tc) = self.im_to_tc_order { - let mut reordered = vec![false; outcomes.len()]; - for (im_idx, &tc_idx) in im_to_tc.iter().enumerate() { - if im_idx < outcomes.len() && tc_idx < reordered.len() { - reordered[tc_idx] = outcomes[im_idx]; - } + maximal_decomposition: bool, + two_detector_direct_policy: TwoDetectorDirectRenderPolicy, + ) -> String { + let mut lines = Vec::new(); + + // Add detector coordinate annotations + for det in &self.detectors { + if let Some([x, y, z]) = det.coords { + lines.push(format!("detector({x}, {y}, {z}) D{}", det.id)); + } else { + lines.push(format!("detector D{}", det.id)); } - reordered - } else { - outcomes.to_vec() - }; + } - Self::to_detection_events_internal(&tc_outcomes, detector_records) - } + // Add standard observable annotations + for obs in &self.observables { + lines.push(format!("logical_observable L{}", obs.id)); + } - /// Internal static helper for detection event conversion. - fn to_detection_events_internal(outcomes: &[bool], detector_records: &[Vec]) -> Vec { - let num_measurements = outcomes.len(); - let mut detection_events = Vec::with_capacity(detector_records.len()); + let graphlike_set = self.collect_graphlike_mechanisms(); + let graphlike_index = GraphlikeDecompositionIndex::new(&graphlike_set); + let singleton_set = maximal_decomposition.then(|| self.collect_singleton_index()); + let mut by_targets: BTreeMap = BTreeMap::new(); + let mut rendered_targets_cache: BTreeMap<(FaultMechanism, FaultSourceType), String> = + BTreeMap::new(); - for records in detector_records { - let mut fired = false; - for &offset in records { - // Convert negative offset to absolute index - #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] // measurement count fits in i32 - #[allow(clippy::cast_sign_loss)] - // negative offset + total count, or non-negative offset - let abs_idx = if offset < 0 { - (num_measurements as i32 + offset) as usize - } else { - offset as usize - }; + let mut add_targets = |targets: String, probability: f64| { + if targets.is_empty() || probability <= 0.0 { + return; + } + by_targets + .entry(targets) + .and_modify(|p| *p = combine_independent_probs(*p, probability)) + .or_insert(probability); + }; - if abs_idx < num_measurements && outcomes[abs_idx] { - fired = !fired; // XOR - } + // Process each tracked contribution individually, then regroup identical + // decomposed outputs. This is closer to Stim's decomposition pass, which + // rewrites each error class before merging identical rewritten targets. + for contrib in &self.contributions { + if contrib.effect.is_empty() || contrib.probability <= 0.0 { + continue; + } + let targets = Self::contribution_targets( + contrib, + &graphlike_index, + singleton_set.as_ref(), + two_detector_direct_policy, + &mut rendered_targets_cache, + ); + add_targets(targets, contrib.probability); + } + + for (targets, total_prob) in by_targets { + if !targets.is_empty() && total_prob > 0.0 { + lines.push(format!( + "error({}) {}", + format_probability(total_prob), + targets + )); } - detection_events.push(fired); } - detection_events + lines.join("\n") } - /// Static version without reordering (for backwards compatibility). #[must_use] - pub fn to_detection_events(outcomes: &[bool], detector_records: &[Vec]) -> Vec { - Self::to_detection_events_internal(outcomes, detector_records) + pub fn to_string_decomposed(&self) -> String { + self.to_string_decomposed_inner(false, TwoDetectorDirectRenderPolicy::KeepDirect) } - /// Samples and converts to detection events in one step. - /// - /// # Arguments - /// - /// * `detector_records` - For each detector, the measurement indices to XOR - /// * `rng` - Random number generator - /// - /// # Returns - /// - /// Tuple of (`measurement_outcomes_in_im_order`, `detection_events`) - pub fn sample_with_detectors( + /// Converts the DEM to decomposed format with an explicit direct-2det + /// rendering policy. + #[must_use] + pub fn to_string_decomposed_with_two_detector_direct_policy( &self, - detector_records: &[Vec], - rng: &mut R, - ) -> (Vec, Vec) { - let outcomes = self.sample(rng); - let detection_events = self.compute_detection_events(&outcomes, detector_records); - (outcomes, detection_events) + two_detector_direct_policy: TwoDetectorDirectRenderPolicy, + ) -> String { + self.to_string_decomposed_inner(false, two_detector_direct_policy) } - /// Computes observable flips from measurement outcomes. - /// - /// This works identically to `compute_detection_events` - `XORing` measurement - /// outcomes at the specified record positions. The difference is semantic: - /// - Detection events indicate which detectors fired (syndrome) - /// - Observable flips indicate which logical observables were flipped - /// - /// # Arguments - /// - /// * `outcomes` - Raw measurement outcomes in influence map order (from `sample()`) - /// * `observable_records` - For each observable, the list of measurement indices to XOR. - /// Indices can be negative (offset from end) or positive (absolute). - /// These indices refer to `TickCircuit` measurement order. + /// Converts the DEM to a maximally decomposed graphlike form when possible. /// - /// # Returns + /// This further rewrites graphlike 2-detector effects into XORs of + /// standalone singleton detector effects whenever those singleton effects + /// already exist in the DEM. /// - /// Vector of observable flips (true = observable was flipped by errors) + /// This is mainly useful for representation inspection or compatibility + /// experiments. It is not generally the preferred MWPM input because + /// replacing pair edges with singleton-heavy structure can degrade the + /// resulting matching graph. #[must_use] - pub fn compute_observable_flips( - &self, - outcomes: &[bool], - observable_records: &[Vec], - ) -> Vec { - // Same logic as detection events - just different semantic meaning - self.compute_detection_events(outcomes, observable_records) + pub fn to_string_decomposed_maximally(&self) -> String { + self.to_string_decomposed_inner(true, TwoDetectorDirectRenderPolicy::KeepDirect) } - /// Samples with full threshold estimation output. - /// - /// Returns detection events AND observable flips in one step, matching - /// Stim's DEM sampler output format. - /// - /// # Arguments - /// - /// * `detector_records` - For each detector, the measurement indices to XOR - /// * `observable_records` - For each observable, the measurement indices to XOR - /// * `rng` - Random number generator - /// - /// # Returns - /// - /// Tuple of (`detection_events`, `observable_flips`) - pub fn sample_for_decoding( + /// Converts the DEM to a maximally decomposed graphlike form with an + /// explicit direct-2det rendering policy. + #[must_use] + pub fn to_string_decomposed_maximally_with_two_detector_direct_policy( &self, - detector_records: &[Vec], - observable_records: &[Vec], - rng: &mut R, - ) -> (Vec, Vec) { - let outcomes = self.sample(rng); - let detection_events = self.compute_detection_events(&outcomes, detector_records); - let observable_flips = self.compute_detection_events(&outcomes, observable_records); - (detection_events, observable_flips) + two_detector_direct_policy: TwoDetectorDirectRenderPolicy, + ) -> String { + self.to_string_decomposed_inner(true, two_detector_direct_policy) } - /// Batch sampling for threshold estimation. - /// - /// Efficiently samples multiple shots and returns detection events and observable - /// flips for each shot. - /// - /// # Arguments - /// - /// * `num_shots` - Number of shots to sample - /// * `detector_records` - For each detector, the measurement indices to XOR - /// * `observable_records` - For each observable, the measurement indices to XOR - /// * `rng` - Random number generator - /// - /// # Returns + /// Collects all graphlike mechanisms from contributions. /// - /// Tuple of (`detection_events_per_shot`, `observable_flips_per_shot`) - pub fn sample_batch_for_decoding( - &self, - num_shots: usize, - detector_records: &[Vec], - observable_records: &[Vec], - rng: &mut R, - ) -> (Vec>, Vec>) { - let mut all_detection_events = Vec::with_capacity(num_shots); - let mut all_observable_flips = Vec::with_capacity(num_shots); - - for _ in 0..num_shots { - let (det_events, obs_flips) = - self.sample_for_decoding(detector_records, observable_records, rng); - all_detection_events.push(det_events); - all_observable_flips.push(obs_flips); + /// Returns a set of mechanisms with ≤2 detectors, + /// which can be used as components for hyperedge decomposition. + fn collect_graphlike_mechanisms(&self) -> BTreeSet { + let mut graphlike = BTreeSet::new(); + for contrib in &self.contributions { + if contrib.effect.is_graphlike() { + graphlike.insert(contrib.effect.clone()); + } } + graphlike + } +} - (all_detection_events, all_observable_flips) +impl Default for DetectorErrorModel { + fn default() -> Self { + Self::new() } } @@ -1795,21 +3287,21 @@ impl MeasurementNoiseModel { /// that exactly one error occurs is: p1*(1-p2) + p2*(1-p1). /// /// This is the correct formula for combining probabilities when the same -/// error mechanism can be triggered by multiple independent error sources. +/// fault mechanism can be triggered by multiple independent error sources. #[inline] #[must_use] pub fn combine_probabilities(p1: f64, p2: f64) -> f64 { p1 * (1.0 - p2) + p2 * (1.0 - p1) } -/// Formats an error mechanism's targets as a string (e.g., "D0 D1 L0"). -fn format_mechanism_targets(mechanism: &ErrorMechanism) -> String { +/// Formats an fault mechanism's targets as a string (e.g., "D0 D1 L0"). +fn format_mechanism_targets(mechanism: &FaultMechanism) -> String { let mut targets = Vec::new(); for &det in &mechanism.detectors { targets.push(format!("D{det}")); } - for &log in &mechanism.logicals { - targets.push(format!("L{log}")); + for &dem_output in &mechanism.dem_outputs { + targets.push(format!("L{dem_output}")); } targets.join(" ") } @@ -1870,25 +3362,25 @@ mod tests { #[test] fn test_error_mechanism_xor() { - let m1 = ErrorMechanism::from_unsorted([0, 1, 2], [0]); - let m2 = ErrorMechanism::from_unsorted([1, 2, 3], [0, 1]); + let m1 = FaultMechanism::from_unsorted([0, 1, 2], [0]); + let m2 = FaultMechanism::from_unsorted([1, 2, 3], [0, 1]); let result = m1.xor(&m2); // Detectors: {0, 1, 2} XOR {1, 2, 3} = {0, 3} assert_eq!(result.detectors.as_slice(), &[0, 3]); - // Logicals: {0} XOR {0, 1} = {1} - assert_eq!(result.logicals.as_slice(), &[1]); + // DEM outputs: {0} XOR {0, 1} = {1} + assert_eq!(result.dem_outputs.as_slice(), &[1]); } #[test] fn test_error_mechanism_equality() { - let m1 = ErrorMechanism::from_unsorted([2, 0, 1], [1, 0]); - let m2 = ErrorMechanism::from_unsorted([0, 1, 2], [0, 1]); + let m1 = FaultMechanism::from_unsorted([2, 0, 1], [1, 0]); + let m2 = FaultMechanism::from_unsorted([0, 1, 2], [0, 1]); assert_eq!(m1, m2); assert_eq!(m1.detectors.as_slice(), &[0, 1, 2]); - assert_eq!(m1.logicals.as_slice(), &[0, 1]); + assert_eq!(m1.dem_outputs.as_slice(), &[0, 1]); } #[test] @@ -1906,10 +3398,361 @@ mod tests { assert!((combine_probabilities(0.0, 0.0)).abs() < 1e-10); } + #[test] + fn test_pecos_metadata_json_preserves_pauli_operator_ops() { + use pecos_core::pauli::constructors::{X, Z}; + + let mut dem = DetectorErrorModel::new(); + dem.add_dem_output( + DemOutput::new(0) + .with_kind(DemOutputKind::TrackedOperator) + .with_pauli(X(0) & Z(2)) + .with_label("track_check"), + ); + dem.add_dem_output(DemOutput::new(1).with_records([-1, -3])); + + let metadata: serde_json::Value = + serde_json::from_str(&dem.to_pecos_metadata_json()).unwrap(); + let observables = metadata["observables"].as_array().unwrap(); + let tracked_ops = metadata["tracked_ops"].as_array().unwrap(); + + assert_eq!(metadata["format"], "pecos.dem.metadata"); + assert_eq!(metadata["version"], 1); + assert_eq!(tracked_ops[0]["id"], 0); + assert_eq!(tracked_ops[0]["kind"], "tracked_operator"); + assert_eq!(tracked_ops[0]["label"], "track_check"); + assert_eq!(tracked_ops[0]["pauli"], "+X0 Z2"); + assert_eq!(observables[0]["id"], 1); + assert_eq!(observables[0]["kind"], "observable"); + assert_eq!(observables[0]["records"], serde_json::json!([-1, -3])); + } + + #[test] + fn test_dem_counts_keep_detectors_observables_and_tracked_operators_distinct() { + use pecos_core::pauli::constructors::X; + + let mut dem = DetectorErrorModel::new(); + dem.add_detector(DetectorDef::new(0).with_records([-1])); + dem.add_dem_output(DemOutput::new(0).with_records([-1, -3])); + dem.add_dem_output( + DemOutput::new(0) + .with_kind(DemOutputKind::TrackedOperator) + .with_pauli(X(0)), + ); + + assert_eq!(dem.num_detectors(), 1); + assert_eq!(dem.num_dem_outputs(), 1); + assert_eq!(dem.num_observables(), 1); + assert_eq!(dem.num_tracked_ops(), 1); + assert_eq!(dem.observables().map(|op| op.id).collect::>(), [0]); + assert_eq!( + dem.tracked_operators().map(|op| op.id).collect::>(), + [0] + ); + } + + #[test] + fn test_dem_output_kind_predicates_are_mutually_exclusive() { + use pecos_core::pauli::constructors::X; + + let observable = DemOutput::new(0) + .with_kind(DemOutputKind::Observable) + .with_pauli(X(0)); + assert!(observable.is_observable()); + assert!(!observable.is_tracked_operator()); + + let tracked = DemOutput::new(0) + .with_kind(DemOutputKind::TrackedOperator) + .with_records([-1]); + assert!(!tracked.is_observable()); + assert!(tracked.is_tracked_operator()); + + let inferred_observable = DemOutput::new(1).with_records([-1]); + assert!(inferred_observable.is_observable()); + assert!(!inferred_observable.is_tracked_operator()); + + let inferred_tracked = DemOutput::new(1).with_pauli(X(1)); + assert!(!inferred_tracked.is_observable()); + assert!(inferred_tracked.is_tracked_operator()); + } + + #[test] + fn test_generic_dem_output_metadata_uses_consistent_kind_name() { + let mut dem = DetectorErrorModel::new(); + dem.add_dem_output(DemOutput::new(0)); + + let metadata: serde_json::Value = + serde_json::from_str(&dem.to_pecos_metadata_json()).unwrap(); + let ops = metadata["observables"].as_array().unwrap(); + + assert_eq!(ops[0]["kind"], "observable"); + + let recovered = DetectorErrorModel::new() + .with_pecos_metadata_json(&dem.to_pecos_metadata_json()) + .unwrap(); + assert_eq!(recovered.num_dem_outputs(), 1); + assert_eq!(recovered.num_tracked_ops(), 0); + assert_eq!(recovered.dem_outputs()[0].id, 0); + assert_eq!(recovered.dem_outputs()[0].kind, Some(DemOutputKind::Observable)); + } + + #[test] + fn test_pecos_metadata_json_round_trips_tracked_operator_metadata() { + use pecos_core::pauli::constructors::{X, Z}; + + let mut dem = DetectorErrorModel::new(); + dem.add_dem_output(DemOutput::new(0)); + dem.add_dem_output(DemOutput::new(1)); + + let mut source = DetectorErrorModel::new(); + source.add_dem_output( + DemOutput::new(0) + .with_kind(DemOutputKind::TrackedOperator) + .with_pauli(X(0) & Z(2)) + .with_label("track_check"), + ); + source.add_dem_output(DemOutput::new(1).with_records([-1, -3])); + + dem.apply_pecos_metadata_json(&source.to_pecos_metadata_json()) + .unwrap(); + + assert_eq!( + dem.tracked_ops()[0].kind, + Some(DemOutputKind::TrackedOperator) + ); + assert_eq!(dem.tracked_ops()[0].label.as_deref(), Some("track_check")); + assert_eq!( + dem.tracked_ops()[0].pauli.as_ref().unwrap().to_sparse_str(), + "+X0 Z2" + ); + assert_eq!(dem.dem_outputs()[1].kind, Some(DemOutputKind::Observable)); + assert_eq!(dem.dem_outputs()[1].records.as_slice(), &[-1, -3]); + } + + #[test] + fn test_pecos_metadata_json_parser_requires_output_arrays() { + let old_metadata_json = r#"{ + "format": "pecos.dem.metadata", + "version": 1, + "old_outputs": [ + { + "id": 4, + "kind": "old_kind", + "label": "old_name", + "pauli": null, + "records": [] + } + ] + }"#; + + let err = DetectorErrorModel::new() + .with_pecos_metadata_json(old_metadata_json) + .unwrap_err(); + assert!( + err.message() + .contains("missing observables or tracked_ops metadata arrays") + ); + } + + #[test] + fn test_pecos_metadata_json_parser_rejects_old_generic_kind_names() { + let json = r#"{ + "format": "pecos.dem.metadata", + "version": 1, + "tracked_ops": [ + { + "id": 4, + "kind": "old_kind", + "label": "old_name", + "pauli": null, + "records": [] + } + ] + }"#; + + let err = DetectorErrorModel::new() + .with_pecos_metadata_json(json) + .unwrap_err(); + assert!( + err.message() + .contains("DEM output 0 has unknown kind: old_kind") + ); + + let alias_json = r#"{ + "format": "pecos.dem.metadata", + "version": 1, + "tracked_ops": [ + { + "id": 4, + "kind": "pauli_operator", + "label": "old_alias", + "pauli": "+X0", + "records": [] + } + ] + }"#; + let err = DetectorErrorModel::new() + .with_pecos_metadata_json(alias_json) + .unwrap_err(); + assert!( + err.message() + .contains("DEM output 0 has unknown kind: pauli_operator") + ); + } + + #[test] + fn test_pecos_metadata_json_rejects_records_on_tracked_operator() { + let json = r#"{ + "format": "pecos.dem.metadata", + "version": 1, + "tracked_ops": [ + { + "id": 0, + "kind": "tracked_operator", + "pauli": "X0", + "records": [-1] + } + ] + }"#; + + let err = DetectorErrorModel::new() + .with_pecos_metadata_json(json) + .unwrap_err(); + assert!( + err.message() + .contains("tracked operator DEM output 0 cannot have measurement records") + ); + } + + #[test] + fn test_pecos_dem_text_is_stim_superset_with_dem_output_metadata() { + use pecos_core::pauli::constructors::{X, Z}; + + let mut dem = DetectorErrorModel::new(); + dem.add_detector(DetectorDef::new(0)); + dem.add_dem_output( + DemOutput::new(0) + .with_kind(DemOutputKind::TrackedOperator) + .with_pauli(X(0) & Z(2)) + .with_label("track_check"), + ); + dem.add_direct_contribution(FaultMechanism::from_unsorted([0], []), 0.01); + + let stim_text = dem.to_string(); + assert!(!stim_text.contains("logical_observable L0")); + assert!(!stim_text.contains("pecos_")); + + let pecos_text = dem.to_pecos_string(); + assert!(pecos_text.starts_with(&stim_text)); + assert!(pecos_text.contains("pecos_tracked_op")); + assert!(pecos_text.contains(r#""kind":"tracked_operator""#)); + assert!(pecos_text.contains(r#""pauli":"+X0 Z2""#)); + + let recovered = DetectorErrorModel::new() + .with_pecos_dem_metadata(&pecos_text) + .unwrap(); + assert_eq!(recovered.num_dem_outputs(), 0); + assert_eq!(recovered.num_tracked_ops(), 1); + assert_eq!( + recovered.tracked_ops()[0].kind, + Some(DemOutputKind::TrackedOperator) + ); + assert_eq!( + recovered.tracked_ops()[0] + .pauli + .as_ref() + .unwrap() + .to_sparse_str(), + "+X0 Z2" + ); + assert_eq!( + recovered.tracked_ops()[0].label.as_deref(), + Some("track_check") + ); + } + + #[test] + fn test_pecos_dem_text_round_trips_observables_and_tracked_ops() { + use pecos_core::pauli::constructors::Z; + + let mut dem = DetectorErrorModel::new(); + dem.add_detector(DetectorDef::new(0)); + dem.add_dem_output(DemOutput::new(0).with_records([-1])); + dem.add_dem_output(DemOutput::new(1).with_records([-2])); + dem.add_dem_output( + DemOutput::new(0) + .with_kind(DemOutputKind::TrackedOperator) + .with_pauli(Z(3)) + .with_label("probe_z3"), + ); + dem.add_direct_contribution(FaultMechanism::from_unsorted([0], [0]), 0.01); + dem.add_direct_contribution(FaultMechanism::from_unsorted([], [1]), 0.02); + + let stim_text = dem.to_string(); + assert!(stim_text.contains("logical_observable L0")); + assert!(stim_text.contains("logical_observable L1")); + assert!(!stim_text.contains("logical_observable L2")); + assert!(!stim_text.contains("pecos_tracked_op")); + + let pecos_text = dem.to_pecos_string(); + assert!(pecos_text.contains("pecos_observable")); + assert!(pecos_text.contains("pecos_tracked_op")); + + let recovered = DetectorErrorModel::new() + .with_pecos_dem_metadata(&pecos_text) + .unwrap(); + assert_eq!(recovered.num_observables(), 2); + assert_eq!(recovered.num_dem_outputs(), 2); + assert_eq!(recovered.num_tracked_ops(), 1); + assert_eq!( + recovered.dem_outputs().iter().map(|op| op.id).collect::>(), + [0, 1] + ); + assert_eq!( + recovered + .tracked_ops() + .iter() + .map(|op| op.id) + .collect::>(), + [0] + ); + assert_eq!( + recovered.tracked_ops()[0].pauli.as_ref().unwrap().to_sparse_str(), + "+Z3" + ); + assert_eq!( + recovered.tracked_ops()[0].label.as_deref(), + Some("probe_z3") + ); + } + + #[test] + fn test_pecos_dem_metadata_parser_rejects_malformed_extension_line() { + let err = DetectorErrorModel::new() + .with_pecos_dem_metadata("error(0.01) D0\npecos_tracked_op not-json") + .unwrap_err(); + assert!( + err.message() + .contains("invalid pecos_tracked_op JSON payload") + ); + } + + #[test] + fn test_pecos_dem_metadata_parser_rejects_unknown_pecos_extension_line() { + let err = DetectorErrorModel::new() + .with_pecos_dem_metadata(r#"pecos_old_extension {"id":1}"#) + .unwrap_err(); + + assert!( + err.message() + .contains("unsupported PECOS DEM extension line") + ); + } + #[test] fn test_decomposed_error_single() { - let mechanism = ErrorMechanism::from_unsorted([0, 1], [0]); - let decomposed = DecomposedError::single(mechanism.clone()); + let mechanism = FaultMechanism::from_unsorted([0, 1], [0]); + let decomposed = DecomposedFault::single(mechanism.clone()); assert_eq!(decomposed.components.len(), 1); assert!(decomposed.is_graphlike()); @@ -1919,9 +3762,9 @@ mod tests { #[test] fn test_decomposed_error_multi() { - let m1 = ErrorMechanism::from_unsorted([0, 1], []); - let m2 = ErrorMechanism::from_unsorted([2, 3], [0]); - let decomposed = DecomposedError::decomposed([m1.clone(), m2.clone()]); + let m1 = FaultMechanism::from_unsorted([0, 1], []); + let m2 = FaultMechanism::from_unsorted([2, 3], [0]); + let decomposed = DecomposedFault::decomposed([m1.clone(), m2.clone()]); assert_eq!(decomposed.components.len(), 2); assert!(decomposed.is_graphlike()); @@ -1934,17 +3777,89 @@ mod tests { assert_eq!(decomposed.to_stim_targets(), "D0 D1 ^ D2 D3 L0"); } + #[test] + fn test_dem_to_string_decomposed_keeps_two_detector_graphlike_edges_direct() { + let mut dem = DetectorErrorModel::new(); + + dem.add_detector(DetectorDef::new(0).with_coords([0.0, 0.0, 0.0])); + dem.add_detector(DetectorDef::new(1).with_coords([1.0, 0.0, 0.0])); + dem.add_dem_output(DemOutput::new(0)); + + dem.add_direct_contribution(FaultMechanism::from_unsorted([0, 1], []), 0.01); + dem.add_direct_contribution(FaultMechanism::from_unsorted([0], [0]), 0.02); + dem.add_direct_contribution(FaultMechanism::from_unsorted([1], [0]), 0.03); + + let stim_str = dem.to_string_decomposed(); + + assert!(stim_str.contains("logical_observable L0")); + assert!(stim_str.contains("error(0.01) D0 D1")); + assert!(!stim_str.contains("D0 L0 ^ D1 L0")); + } + + #[test] + fn test_dem_to_string_decomposed_maximally_prefers_singletons_when_available() { + let mut dem = DetectorErrorModel::new(); + + dem.add_detector(DetectorDef::new(0).with_coords([0.0, 0.0, 0.0])); + dem.add_detector(DetectorDef::new(1).with_coords([1.0, 0.0, 0.0])); + + dem.add_direct_contribution(FaultMechanism::from_unsorted([0, 1], []), 0.01); + dem.add_direct_contribution(FaultMechanism::from_unsorted([0], std::iter::empty()), 0.02); + dem.add_direct_contribution(FaultMechanism::from_unsorted([1], std::iter::empty()), 0.03); + + let decomposed = dem.to_string_decomposed(); + let maximal = dem.to_string_decomposed_maximally(); + + assert!(decomposed.contains("error(0.01) D0 D1")); + assert!(!decomposed.contains("error(0.01) D0 ^ D1")); + + assert!(maximal.contains("error(0.01) D0 ^ D1")); + assert!(!maximal.contains("error(0.01) D0 D1")); + } + + #[test] + fn test_contribution_effect_summaries_include_graphlike_decomposable_count() { + let mut dem = DetectorErrorModel::new(); + + dem.add_direct_contribution( + FaultMechanism::from_unsorted([0, 1], std::iter::empty()), + 0.01, + ); + dem.add_direct_contribution(FaultMechanism::from_unsorted([0], std::iter::empty()), 0.02); + dem.mark_graphlike_decomposable(0, 1); + dem.mark_graphlike_decomposable(1, 0); + + let summaries = dem.contribution_effect_summaries(); + + let pair_summary = summaries + .iter() + .find(|summary| { + summary.effect.detectors.as_slice() == [0, 1] + && summary.effect.dem_outputs.is_empty() + }) + .expect("pair summary missing"); + assert_eq!(pair_summary.graphlike_decomposable_count, 2); + + let singleton_summary = summaries + .iter() + .find(|summary| { + summary.effect.detectors.as_slice() == [0] && summary.effect.dem_outputs.is_empty() + }) + .expect("singleton summary missing"); + assert_eq!(singleton_summary.graphlike_decomposable_count, 0); + } + #[test] fn test_dem_to_string() { let mut dem = DetectorErrorModel::new(); dem.add_detector(DetectorDef::new(0).with_coords([0.0, 0.0, 0.0])); dem.add_detector(DetectorDef::new(1).with_coords([1.0, 0.0, 0.0])); - dem.add_observable(LogicalObservable::new(0)); + dem.add_dem_output(DemOutput::new(0)); // Add contributions directly using the source tracking API - dem.add_direct_contribution(ErrorMechanism::from_unsorted([0, 1], []), 0.01); - dem.add_direct_contribution(ErrorMechanism::from_unsorted([1], [0]), 0.005); + dem.add_direct_contribution(FaultMechanism::from_unsorted([0, 1], []), 0.01); + dem.add_direct_contribution(FaultMechanism::from_unsorted([1], [0]), 0.005); let stim_str = dem.to_string(); @@ -1954,4 +3869,253 @@ mod tests { assert!(stim_str.contains("error(0.01) D0 D1")); assert!(stim_str.contains("error(0.005) D1 L0")); } + + #[test] + fn test_dem_to_string_decomposed_keeps_two_detector_one_dem_output_direct() { + let mut dem = DetectorErrorModel::new(); + + dem.add_detector(DetectorDef::new(0).with_coords([0.0, 0.0, 0.0])); + dem.add_detector(DetectorDef::new(1).with_coords([1.0, 0.0, 0.0])); + dem.add_dem_output(DemOutput::new(0)); + + dem.add_direct_contribution(FaultMechanism::from_unsorted([0, 1], [0]), 0.01); + dem.add_direct_contribution(FaultMechanism::from_unsorted([0], std::iter::empty()), 0.02); + dem.add_direct_contribution(FaultMechanism::from_unsorted([1], [0]), 0.03); + + let stim_str = dem.to_string_decomposed(); + + assert!(stim_str.contains("error(0.01) D0 D1 L0")); + assert!(!stim_str.contains("error(0.01) D0 ^ D1 L0")); + } + + #[test] + fn test_dem_to_string_decomposed_uses_y_components_when_graphlike() { + let mut dem = DetectorErrorModel::new(); + + dem.add_detector(DetectorDef::new(0).with_coords([0.0, 0.0, 0.0])); + dem.add_detector(DetectorDef::new(1).with_coords([1.0, 0.0, 0.0])); + dem.add_dem_output(DemOutput::new(0)); + + let x = FaultMechanism::from_unsorted([0], std::iter::empty()); + let z = FaultMechanism::from_unsorted([1], [0]); + dem.add_y_decomposed_contribution(&x, &z, 0.01); + + let stim_str = dem.to_string_decomposed(); + + assert!(stim_str.contains("error(0.01) D0 ^ D1 L0")); + assert!(!stim_str.contains("error(0.01) D0 D1 L0")); + } + + #[test] + fn test_error_mechanism_with_two_detectors_and_multiple_dem_outputs_is_graphlike() { + let effect = FaultMechanism::from_unsorted([0, 1], [0, 1]); + + assert!(effect.is_graphlike()); + assert!(!effect.is_hyperedge()); + } + + #[test] + fn test_find_hyperedge_decomposition_returns_graphlike_subset_components() { + let hyperedge = FaultMechanism::from_unsorted([0, 1, 2], [0]); + let graphlike_set = BTreeSet::from([ + FaultMechanism::from_unsorted([0], std::iter::empty()), + FaultMechanism::from_unsorted([1], std::iter::empty()), + FaultMechanism::from_unsorted([2], [0]), + FaultMechanism::from_unsorted([0, 1], std::iter::empty()), + ]); + + let decomposition = find_hyperedge_decomposition(&hyperedge, &graphlike_set) + .expect("expected a valid decomposition"); + let hyperedge_dets: BTreeSet = hyperedge.detectors.iter().copied().collect(); + + let recomposed = decomposition + .iter() + .fold(FaultMechanism::new(), |acc, part| acc.xor(part)); + assert_eq!(recomposed, hyperedge); + assert!( + decomposition + .iter() + .all(super::FaultMechanism::is_graphlike) + ); + assert!( + decomposition + .iter() + .flat_map(|part| part.detectors.iter()) + .all(|det| hyperedge_dets.contains(det)) + ); + assert_eq!(decomposition.len(), 2); + } + + #[test] + fn test_find_hyperedge_decomposition_can_use_four_parts() { + let hyperedge = FaultMechanism::from_unsorted([0, 1, 2, 3], [0]); + let graphlike_set = BTreeSet::from([ + FaultMechanism::from_unsorted([0], std::iter::empty()), + FaultMechanism::from_unsorted([1], std::iter::empty()), + FaultMechanism::from_unsorted([2], std::iter::empty()), + FaultMechanism::from_unsorted([3], [0]), + ]); + + let decomposition = find_hyperedge_decomposition(&hyperedge, &graphlike_set) + .expect("expected a valid decomposition"); + + let recomposed = decomposition + .iter() + .fold(FaultMechanism::new(), |acc, part| acc.xor(part)); + assert_eq!(recomposed, hyperedge); + assert!( + decomposition + .iter() + .all(super::FaultMechanism::is_graphlike) + ); + assert_eq!(decomposition.len(), 4); + } + + #[test] + fn test_contributions_for_effect_matches_observable_coupled_effects() { + let mut dem = DetectorErrorModel::new(); + let effect = FaultMechanism::from_unsorted([0, 1], [0]); + + dem.add_direct_contribution(effect.clone(), 0.01); + + let matches = dem.contributions_for_effect(&[1, 0], &[0]); + assert_eq!(matches.len(), 1); + assert_eq!(matches[0].effect, effect); + assert!(matches[0].is_direct()); + } + + #[test] + fn test_contribution_effect_summaries_split_direct_and_y_contributions() { + let mut dem = DetectorErrorModel::new(); + let effect = FaultMechanism::from_unsorted([0, 1], [0]); + + dem.add_direct_contribution(effect.clone(), 0.01); + let x = FaultMechanism::from_unsorted([0], std::iter::empty()); + let z = FaultMechanism::from_unsorted([1], [0]); + dem.add_y_decomposed_contribution(&x, &z, 0.02); + + let summary = dem + .contribution_effect_summaries() + .into_iter() + .find(|row| row.effect == effect) + .expect("expected a summary for the shared effect"); + + assert_eq!(summary.num_contributions, 2); + assert!((summary.total_probability - 0.03).abs() < 1e-12); + assert_eq!(summary.direct_count, 1); + assert!((summary.direct_probability - 0.01).abs() < 1e-12); + assert_eq!(summary.y_decomposed_count, 1); + assert!((summary.y_decomposed_probability - 0.02).abs() < 1e-12); + } + + #[test] + fn test_add_y_decomposed_contribution_routes_one_empty_branch_to_direct() { + let mut dem = DetectorErrorModel::new(); + let x = FaultMechanism::new(); + let z = FaultMechanism::from_unsorted([1, 44], std::iter::empty()); + + dem.add_y_decomposed_contribution(&x, &z, 0.02); + + let summary = dem + .contribution_effect_summaries() + .into_iter() + .find(|row| row.effect == z) + .expect("expected summary for graphlike direct effect"); + + assert_eq!(summary.direct_count, 1); + assert_eq!(summary.y_decomposed_count, 0); + assert!((summary.direct_probability - 0.02).abs() < 1e-12); + } + + #[test] + fn test_direct_with_source_components_xor_back_to_effect() { + let effect = FaultMechanism::from_unsorted([0, 1], std::iter::empty()); + let first = FaultMechanism::from_unsorted([0], std::iter::empty()); + let second = FaultMechanism::from_unsorted([1], std::iter::empty()); + + let contribution = FaultContribution::direct_with_source_components( + effect.clone(), + 0.01, + SourceMetadata::new( + &[3, 4], + &[Pauli::Z, Pauli::I], + &[GateType::CX, GateType::CX], + &[false, false], + ), + DirectSourceComponents::new(&first, &second), + ); + + assert!(contribution.is_direct()); + let (left, right) = contribution + .direct_component_effects() + .expect("expected direct component effects"); + assert_eq!(left.xor(&right), effect); + assert!(matches!(contribution.source_type, FaultSourceType::Direct)); + } + + #[test] + fn test_direct_with_source_components_marks_one_sided_component_sources() { + let effect = FaultMechanism::from_unsorted([7, 11], std::iter::empty()); + let first = effect.clone(); + let second = FaultMechanism::new(); + + let contribution = FaultContribution::direct_with_source_components( + effect.clone(), + 0.01, + SourceMetadata::new( + &[3, 4], + &[Pauli::Z, Pauli::I], + &[GateType::CX, GateType::CX], + &[false, false], + ), + DirectSourceComponents::new(&first, &second), + ); + + assert!(contribution.is_direct()); + assert!(matches!( + contribution.source_type, + FaultSourceType::DirectOneSidedComponent + )); + assert_eq!( + contribution.direct_source_family, + Some(DirectSourceFamily::TwoLocationOneSidedComponent) + ); + let (left, right) = contribution + .direct_component_effects() + .expect("expected direct component effects"); + assert_eq!(left, effect); + assert!(right.is_empty()); + assert_eq!( + contribution.source_gate_types.as_slice(), + &[GateType::CX, GateType::CX] + ); + assert_eq!(contribution.source_before_flags.as_slice(), &[false, false]); + } + + #[test] + fn test_add_y_decomposed_contribution_with_source_routes_metadata_to_direct() { + let mut dem = DetectorErrorModel::new(); + let x = FaultMechanism::new(); + let z = FaultMechanism::from_unsorted([1, 44], std::iter::empty()); + + dem.add_y_decomposed_contribution_with_source( + &x, + &z, + 0.02, + SourceMetadata::new(&[7], &[Pauli::Y], &[GateType::H], &[false]), + ); + + let contributions = dem.contributions_for_effect(&[1, 44], &[]); + assert_eq!(contributions.len(), 1); + let contribution = &contributions[0]; + assert!(matches!(contribution.source_type, FaultSourceType::Direct)); + assert_eq!(contribution.location_indices.as_slice(), &[7]); + assert_eq!(contribution.paulis.as_slice(), &[Pauli::Y]); + assert_eq!(contribution.source_gate_types.as_slice(), &[GateType::H]); + assert_eq!(contribution.source_before_flags.as_slice(), &[false]); + assert_eq!( + contribution.direct_source_family, + Some(DirectSourceFamily::SingleLocationY) + ); + } } diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs new file mode 100644 index 000000000..5ebbc1060 --- /dev/null +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -0,0 +1,3256 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Stochastic raw-measurement sampling via fault table overlay. +//! +//! # Architecture +//! +//! Raw measurement output = ideal measurement values XOR sampled physical faults. +//! +//! These are computed independently: +//! - **Ideal values** from [`MeasurementSampler`](pecos_simulators::measurement_sampler::MeasurementSampler), +//! which respects the Copy/Computed dependency graph from symbolic simulation. +//! Non-deterministic measurements share latent random variables through the +//! stabilizer eigenvalue structure. +//! - **Physical faults** from a fault table where each entry has a probability +//! and a set of affected measurements. Faults are sampled independently per +//! shot (Bernoulli) and XOR'd onto the ideal values. +//! +//! This separation is critical: the dependency graph captures *ideal* measurement +//! correlations (same stabilizer across resets), while fault events represent +//! *physical* noise processes (gate errors, measurement flips, prep errors). +//! Mixing them — e.g., flattening fault deps through Copy chains — incorrectly +//! cancels faults that affect only one measurement in a correlated pair. + +use pecos_core::gate_type::GateType; +use pecos_core::pauli::pauli_string::PauliString; +use pecos_core::{Pauli, QubitId}; +use pecos_quantum::{AnnotationKind, TickCircuit}; +use pecos_random::{PecosRng, RngExt}; +use pecos_simulators::measurement_sampler::{MeasurementKind, SampleResult}; +use pecos_simulators::pauli_prop::PauliProp; +use pecos_simulators::symbolic_sparse_stab::MeasurementHistory; +use pecos_simulators::CliffordGateable; +use std::collections::{BTreeSet, HashMap}; +use std::fmt; + +/// Error returned when `build_fault_table` encounters an unsupported gate. +#[derive(Clone, Debug)] +pub struct UnsupportedGateError { + pub gate_type: GateType, + pub tick: usize, + pub gate_in_tick: usize, + pub qubits: Vec, +} + +impl fmt::Display for UnsupportedGateError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!( + f, + "Unsupported gate {:?} at tick {} gate {} on qubits {:?}. \ + Supported: H, X, Y, Z, SZ, SZdg, SX, SXdg, SY, SYdg, F, Fdg, \ + CX, CY, CZ, SXX, SXXdg, SYY, SYYdg, SZZ, SZZdg, SWAP, \ + MZ/MeasureFree/MeasureLeaked, PZ, QAlloc, QFree, I, Idle, \ + plus metadata (MeasCrosstalk*, PauliOperatorMeta).", + self.gate_type, self.tick, self.gate_in_tick, self.qubits + ) + } +} + +impl std::error::Error for UnsupportedGateError {} + +/// Standard single-qubit Clifford gates supported by `CliffordGateable`. +pub const STANDARD_1Q_CLIFFORD_GATES: &[GateType] = &[ + GateType::X, + GateType::Y, + GateType::Z, + GateType::H, + GateType::SZ, + GateType::SZdg, + GateType::SX, + GateType::SXdg, + GateType::SY, + GateType::SYdg, + GateType::F, + GateType::Fdg, +]; + +/// Standard two-qubit Clifford gates supported by `CliffordGateable`. +pub const STANDARD_2Q_CLIFFORD_GATES: &[GateType] = &[ + GateType::CX, + GateType::CY, + GateType::CZ, + GateType::SXX, + GateType::SXXdg, + GateType::SYY, + GateType::SYYdg, + GateType::SZZ, + GateType::SZZdg, + GateType::SWAP, +]; + +#[inline] +fn is_standard_1q_clifford_gate(gate_type: GateType) -> bool { + STANDARD_1Q_CLIFFORD_GATES.contains(&gate_type) +} + +#[inline] +fn is_standard_2q_clifford_gate(gate_type: GateType) -> bool { + STANDARD_2Q_CLIFFORD_GATES.contains(&gate_type) +} + +#[inline] +fn is_supported_measurement_gate(gate_type: GateType) -> bool { + matches!( + gate_type, + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked + ) +} + +#[inline] +fn is_supported_prep_gate(gate_type: GateType) -> bool { + matches!(gate_type, GateType::PZ | GateType::QAlloc) +} + +#[inline] +fn is_supported_noop_or_metadata_gate(gate_type: GateType) -> bool { + matches!( + gate_type, + GateType::QFree + | GateType::I + | GateType::Idle + | GateType::MeasCrosstalkGlobalPayload + | GateType::MeasCrosstalkLocalPayload + | GateType::PauliOperatorMeta + ) +} + +/// A fault mechanism: fires with probability `p`, then uniformly selects one +/// of its alternatives to determine which measurements are flipped. +/// +/// For a depolarizing channel with k non-identity Paulis and total error +/// probability p: the mechanism fires with probability p, then each of the +/// k alternatives is chosen with probability 1/k. This matches the stabilizer +/// sim's "exactly one Pauli error per gate event" semantics. +#[derive(Clone, Debug)] +pub struct FaultMechanism { + /// Total probability that this mechanism fires (one Bernoulli per shot). + pub probability: f64, + /// Each alternative is a set of measurements that get flipped if that + /// alternative is selected. Empty alternatives (no measurements flipped) + /// are preserved — they represent Pauli errors that commute with all + /// subsequent measurements (e.g., Z after MZ). Keeping them maintains + /// the correct 1/k uniform denominator for the depolarizing channel. + pub alternatives: Vec>, +} + +/// Noise parameters for depolarizing fault injection. +#[derive(Clone, Debug)] +pub struct StochasticNoiseParams { + pub p1: f64, + pub p2: f64, + pub p_meas: f64, + pub p_prep: f64, +} + +/// A gate in the flattened gate list (one entry per qubit-pair or single qubit). +#[derive(Clone, Debug)] +pub(crate) struct GateLoc { + pub(crate) gate_type: GateType, + pub(crate) qubits: Vec, +} + +/// Single-qubit Pauli type for fault injection. +#[derive(Clone, Copy, Debug, PartialEq, Eq)] +pub(crate) enum PauliType { + X, + Y, + Z, +} + +/// Build a fault table from a TickCircuit and noise parameters. +/// +/// Each entry describes one possible fault mechanism: its probability and +/// which measurements it would flip if it occurs. The table is used for +/// independent per-shot Bernoulli sampling. +/// +/// Gate ordering follows the TickCircuit tick-by-tick structure, which must +/// match the measurement numbering used by detector/DEM-output record indices. +/// +/// # Supported gates +/// +/// **Fault injection** (noise applied after these gates): +/// - Single-qubit Clifford: H, X, Y, Z, SZ, SZdg, SX, SXdg, SY, SYdg, F, Fdg → p=p1, 3 alternatives +/// - Two-qubit Clifford: CX, CY, CZ, SXX, SXXdg, SYY, SYYdg, SZZ, SZZdg, SWAP → p=p2, 15 alts +/// - State preparation: PZ, QAlloc → mechanism with p=p_prep, 1 alternative (X) +/// - Measurement: MZ, MeasureFree, MeasureLeaked → mechanism with p=p_meas, 1 alternative (flip) +/// +/// Each mechanism fires at most once per shot (Bernoulli with total probability p). +/// When it fires, exactly one alternative is chosen uniformly at random. This +/// matches the depolarizing channel semantics: "with probability p, apply one +/// of the k non-identity Paulis, each equally likely." +/// +/// **Propagation** (gates that transform a propagating Pauli): +/// - All single-qubit Cliffords: Clifford conjugation via direct Pauli-basis updates +/// - All two-qubit Cliffords: Clifford conjugation via direct Pauli-basis updates +/// - PZ, QAlloc: absorbs all Pauli components on the reset qubit +/// - MZ: records X-component flip, then absorbs all components (state collapse) +/// +/// **No-op** (pass through without noise or transformation): +/// - I, Idle, QFree, MeasCrosstalkGlobalPayload, MeasCrosstalkLocalPayload, PauliOperatorMeta +/// +/// Any gate not in the above lists returns [`UnsupportedGateError`]. +/// +pub fn build_fault_table( + tc: &TickCircuit, + noise: &StochasticNoiseParams, +) -> Result, UnsupportedGateError> { + validate_tick_circuit(tc)?; + let (gates, meas_positions) = flatten_tick_circuit(tc); + + if noise.p1 == 0.0 && noise.p2 == 0.0 && noise.p_meas == 0.0 && noise.p_prep == 0.0 { + return Ok(Vec::new()); + } + let mut mechanisms = Vec::new(); + + for (loc_idx, loc) in gates.iter().enumerate() { + match loc.gate_type { + // Single-qubit Clifford: one mechanism with 3 alternatives (X/Y/Z) + gate_type + if is_standard_1q_clifford_gate(gate_type) + && noise.p1 > 0.0 + && !loc.qubits.is_empty() => + { + let q = loc.qubits[0]; + let alts: Vec> = [PauliType::X, PauliType::Y, PauliType::Z] + .iter() + .map(|&p| { + propagate_single(p, q, loc_idx + 1, &gates, &meas_positions) + .into_iter() + .collect() + }) + .collect(); + // Only include if at least one alternative has an effect + if alts.iter().any(|a| !a.is_empty()) { + mechanisms.push(FaultMechanism { + probability: noise.p1, + alternatives: alts, + }); + } + } + + // Two-qubit Clifford: one mechanism with 15 alternatives + gate_type + if is_standard_2q_clifford_gate(gate_type) + && noise.p2 > 0.0 + && loc.qubits.len() >= 2 => + { + let (q1, q2) = (loc.qubits[0], loc.qubits[1]); + let paulis = [PauliType::X, PauliType::Y, PauliType::Z]; + let mut alts: Vec> = Vec::new(); + + // 9 two-qubit pairs + for &p1 in &paulis { + for &p2 in &paulis { + let a: Vec = + propagate_pair(p1, q1, p2, q2, loc_idx + 1, &gates, &meas_positions) + .into_iter() + .collect(); + alts.push(a); + } + } + // 6 single-qubit (PI and IP) + for &p in &paulis { + let a: Vec = + propagate_single(p, q1, loc_idx + 1, &gates, &meas_positions) + .into_iter() + .collect(); + alts.push(a); + let a: Vec = + propagate_single(p, q2, loc_idx + 1, &gates, &meas_positions) + .into_iter() + .collect(); + alts.push(a); + } + if alts.iter().any(|a| !a.is_empty()) { + mechanisms.push(FaultMechanism { + probability: noise.p2, + alternatives: alts, + }); + } + } + + // State preparation: single alternative (X error) + GateType::PZ | GateType::QAlloc if noise.p_prep > 0.0 && !loc.qubits.is_empty() => { + let q = loc.qubits[0]; + let a: Vec = + propagate_single(PauliType::X, q, loc_idx + 1, &gates, &meas_positions) + .into_iter() + .collect(); + if !a.is_empty() { + mechanisms.push(FaultMechanism { + probability: noise.p_prep, + alternatives: vec![a], + }); + } + } + + // Measurement fault: single alternative (flip this measurement) + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked + if noise.p_meas > 0.0 => + { + if let Some(&meas_idx) = meas_positions.get(&loc_idx) { + mechanisms.push(FaultMechanism { + probability: noise.p_meas, + alternatives: vec![vec![meas_idx]], + }); + } + } + + _ => {} + } + } + + Ok(mechanisms) +} + +/// Validate that all gates in the TickCircuit are supported (before flattening). +fn validate_tick_circuit(tc: &TickCircuit) -> Result<(), UnsupportedGateError> { + for (tick_idx, tick) in tc.ticks().iter().enumerate() { + for (gate_idx, gate) in tick.gates().iter().enumerate() { + if is_standard_1q_clifford_gate(gate.gate_type) + || is_standard_2q_clifford_gate(gate.gate_type) + || is_supported_measurement_gate(gate.gate_type) + || is_supported_prep_gate(gate.gate_type) + || is_supported_noop_or_metadata_gate(gate.gate_type) + { + continue; + } + return Err(UnsupportedGateError { + gate_type: gate.gate_type, + tick: tick_idx, + gate_in_tick: gate_idx, + qubits: gate.qubits.iter().map(|q| q.index()).collect(), + }); + } + } + Ok(()) +} + +/// Flatten a TickCircuit into a gate list with measurement position tracking. +/// +/// Multi-qubit gates are split into individual entries so each measurement/pair +/// gets its own position for fault injection. Returns the gate list and a map +/// from gate-list index to measurement index. +pub(crate) fn flatten_tick_circuit(tc: &TickCircuit) -> (Vec, HashMap) { + let mut gates = Vec::new(); + let mut meas_positions = HashMap::new(); + let mut meas_count = 0usize; + + for tick in tc.ticks() { + for gate in tick.gates() { + let qs: Vec = gate.qubits.iter().map(|q| q.index()).collect(); + let is_mz = is_supported_measurement_gate(gate.gate_type); + let is_2q = is_standard_2q_clifford_gate(gate.gate_type); + + if is_mz && qs.len() > 1 { + for &q in &qs { + meas_positions.insert(gates.len(), meas_count); + meas_count += 1; + gates.push(GateLoc { + gate_type: gate.gate_type, + qubits: vec![q], + }); + } + } else if is_2q && qs.len() > 2 { + for pair in qs.chunks(2).filter(|c| c.len() == 2) { + gates.push(GateLoc { + gate_type: gate.gate_type, + qubits: vec![pair[0], pair[1]], + }); + } + } else if qs.len() > 1 && !is_2q && !is_mz { + for &q in &qs { + gates.push(GateLoc { + gate_type: gate.gate_type, + qubits: vec![q], + }); + } + } else { + if is_mz { + meas_positions.insert(gates.len(), meas_count); + meas_count += 1; + } + gates.push(GateLoc { + gate_type: gate.gate_type, + qubits: qs, + }); + } + } + } + + (gates, meas_positions) +} + +/// Propagate a single-qubit Pauli fault forward through the gate list. +/// +/// Returns the set of measurement indices whose outcomes would be flipped +/// by this Pauli error at this position. +pub(crate) fn propagate_single( + pauli: PauliType, + qubit: usize, + start: usize, + gates: &[GateLoc], + meas_positions: &HashMap, +) -> BTreeSet { + let mut prop = PauliProp::new(); + match pauli { + PauliType::X => prop.track_x(&[qubit]), + PauliType::Y => prop.track_y(&[qubit]), + PauliType::Z => prop.track_z(&[qubit]), + }; + + propagate_forward(&mut prop, start, gates, meas_positions) +} + +fn propagate_single_effect( + pauli: PauliType, + qubit: usize, + start: usize, + gates: &[GateLoc], + meas_positions: &HashMap, + tracked_ops: &[PauliString], +) -> PropagatedFaultEffect { + let mut prop = PauliProp::new(); + match pauli { + PauliType::X => prop.track_x(&[qubit]), + PauliType::Y => prop.track_y(&[qubit]), + PauliType::Z => prop.track_z(&[qubit]), + }; + + let affected_measurements = propagate_forward(&mut prop, start, gates, meas_positions); + let affected_tracked_ops = tracked_ops_flipped_by(&prop, tracked_ops); + PropagatedFaultEffect { + affected_measurements, + affected_tracked_ops, + } +} + +/// Propagate a two-qubit Pauli fault forward through the gate list. +fn propagate_pair( + p1: PauliType, + q1: usize, + p2: PauliType, + q2: usize, + start: usize, + gates: &[GateLoc], + meas_positions: &HashMap, +) -> BTreeSet { + let mut prop = PauliProp::new(); + match p1 { + PauliType::X => prop.track_x(&[q1]), + PauliType::Y => prop.track_y(&[q1]), + PauliType::Z => prop.track_z(&[q1]), + }; + match p2 { + PauliType::X => prop.track_x(&[q2]), + PauliType::Y => prop.track_y(&[q2]), + PauliType::Z => prop.track_z(&[q2]), + }; + + propagate_forward(&mut prop, start, gates, meas_positions) +} + +fn propagate_pair_effect( + p1: PauliType, + q1: usize, + p2: PauliType, + q2: usize, + start: usize, + gates: &[GateLoc], + meas_positions: &HashMap, + tracked_ops: &[PauliString], +) -> PropagatedFaultEffect { + let mut prop = PauliProp::new(); + match p1 { + PauliType::X => prop.track_x(&[q1]), + PauliType::Y => prop.track_y(&[q1]), + PauliType::Z => prop.track_z(&[q1]), + }; + match p2 { + PauliType::X => prop.track_x(&[q2]), + PauliType::Y => prop.track_y(&[q2]), + PauliType::Z => prop.track_z(&[q2]), + }; + + let affected_measurements = propagate_forward(&mut prop, start, gates, meas_positions); + let affected_tracked_ops = tracked_ops_flipped_by(&prop, tracked_ops); + PropagatedFaultEffect { + affected_measurements, + affected_tracked_ops, + } +} + +struct PropagatedFaultEffect { + affected_measurements: BTreeSet, + affected_tracked_ops: Vec, +} + +/// Core forward propagation: evolve a Pauli through gates, collecting affected measurements. +fn propagate_forward( + prop: &mut PauliProp, + start: usize, + gates: &[GateLoc], + meas_positions: &HashMap, +) -> BTreeSet { + let mut affected = BTreeSet::new(); + + for (loc_idx, loc) in gates.iter().enumerate().skip(start) { + match loc.gate_type { + GateType::H if !loc.qubits.is_empty() => { + prop.h(&[QubitId(loc.qubits[0])]); + } + GateType::SZ if !loc.qubits.is_empty() => { + prop.sz(&[QubitId(loc.qubits[0])]); + } + GateType::SZdg if !loc.qubits.is_empty() => { + let q = QubitId(loc.qubits[0]); + prop.szdg(&[q]); + } + GateType::SX if !loc.qubits.is_empty() => { + prop.sx(&[QubitId(loc.qubits[0])]); + } + GateType::SXdg if !loc.qubits.is_empty() => { + prop.sxdg(&[QubitId(loc.qubits[0])]); + } + GateType::SY if !loc.qubits.is_empty() => { + prop.sy(&[QubitId(loc.qubits[0])]); + } + GateType::SYdg if !loc.qubits.is_empty() => { + prop.sydg(&[QubitId(loc.qubits[0])]); + } + GateType::F if !loc.qubits.is_empty() => { + prop.f(&[QubitId(loc.qubits[0])]); + } + GateType::Fdg if !loc.qubits.is_empty() => { + prop.fdg(&[QubitId(loc.qubits[0])]); + } + GateType::CX if loc.qubits.len() >= 2 => { + prop.cx(&[(QubitId(loc.qubits[0]), QubitId(loc.qubits[1]))]); + } + GateType::CY if loc.qubits.len() >= 2 => { + let (q1, q2) = (QubitId(loc.qubits[0]), QubitId(loc.qubits[1])); + prop.cy(&[(q1, q2)]); + } + GateType::CZ if loc.qubits.len() >= 2 => { + let (q1, q2) = (QubitId(loc.qubits[0]), QubitId(loc.qubits[1])); + prop.cz(&[(q1, q2)]); + } + GateType::SXX if loc.qubits.len() >= 2 => { + let pair = [(QubitId(loc.qubits[0]), QubitId(loc.qubits[1]))]; + prop.sxx(&pair); + } + GateType::SXXdg if loc.qubits.len() >= 2 => { + let pair = [(QubitId(loc.qubits[0]), QubitId(loc.qubits[1]))]; + prop.sxxdg(&pair); + } + GateType::SYY if loc.qubits.len() >= 2 => { + let pair = [(QubitId(loc.qubits[0]), QubitId(loc.qubits[1]))]; + prop.syy(&pair); + } + GateType::SYYdg if loc.qubits.len() >= 2 => { + let pair = [(QubitId(loc.qubits[0]), QubitId(loc.qubits[1]))]; + prop.syydg(&pair); + } + GateType::SZZ if loc.qubits.len() >= 2 => { + let pair = [(QubitId(loc.qubits[0]), QubitId(loc.qubits[1]))]; + prop.szz(&pair); + } + GateType::SZZdg if loc.qubits.len() >= 2 => { + let pair = [(QubitId(loc.qubits[0]), QubitId(loc.qubits[1]))]; + prop.szzdg(&pair); + } + GateType::SWAP if loc.qubits.len() >= 2 => { + let pair = [(QubitId(loc.qubits[0]), QubitId(loc.qubits[1]))]; + prop.swap(&pair); + } + // PZ/QAlloc absorbs propagating errors on the reset qubit + GateType::PZ | GateType::QAlloc if !loc.qubits.is_empty() => { + prop.clear_qubit(loc.qubits[0]); + } + // MZ: X component flips the measurement, then qubit state collapses + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked + if !loc.qubits.is_empty() => + { + let q = loc.qubits[0]; + if prop.contains_x(q) { + if let Some(&meas_idx) = meas_positions.get(&loc_idx) { + affected.insert(meas_idx); + } + } + prop.clear_qubit(q); + } + _ => {} + } + } + + affected +} + +// ============================================================================ +// Fault Catalog: per-location, per-alternative lookup table +// ============================================================================ + +/// The kind of physical fault mechanism. +#[derive(Clone, Debug, PartialEq, Eq)] +pub enum FaultKind { + /// A Pauli error injected after a gate. + Pauli, + /// A measurement outcome flip. + MeasurementFlip, + /// A preparation error (X on |0⟩). + PrepFlip, +} + +/// Which noise channel produced this fault location. +#[derive(Clone, Debug, PartialEq, Eq)] +pub enum FaultChannel { + /// Single-qubit depolarizing (p1). + P1, + /// Two-qubit depolarizing (p2). + P2, + /// Measurement flip (p_meas). + PMeas, + /// State preparation flip (p_prep). + PPrep, +} + +/// One alternative within a physical fault location. +#[derive(Clone, Debug)] +pub struct FaultAlternative { + /// Kind of fault. + pub kind: FaultKind, + /// The Pauli error for this alternative (None for measurement/prep faults). + pub pauli: Option, + /// Raw measurement indices flipped by this fault. + pub affected_measurements: Vec, + /// Detector indices flipped (computed from measurement effects + detector records). + pub affected_detectors: Vec, + /// Observable indices flipped. + pub affected_observables: Vec, + /// Tracked-operator indices flipped. + pub affected_tracked_ops: Vec, + /// Probability of this alternative conditioned on the mechanism firing (1/k). + pub conditional_probability: f64, + /// Marginal probability of this specific alternative at this location: p_i / k_i. + /// + /// This is NOT "probability of this fault and no others." A full-circuit + /// configuration probability requires multiplying by (1 - p_j) for all + /// other locations j. + pub absolute_probability: f64, +} + +/// A physical fault location in the circuit. +#[derive(Clone, Debug)] +pub struct FaultLocation { + /// Tick index in the TickCircuit. + pub tick: usize, + /// Gate index within the tick. + pub gate_index: usize, + /// Gate type at this location. + pub gate_type: GateType, + /// Qubits involved. + pub qubits: Vec, + /// Which noise channel this location belongs to. + pub channel: FaultChannel, + /// Total probability that this mechanism fires: p_i. + pub channel_probability: f64, + /// Probability that no fault occurs at this location: 1 - p_i. + pub no_fault_probability: f64, + /// Number of fault alternatives at this location: k_i. + pub num_alternatives: usize, + /// All fault alternatives at this location. + pub faults: Vec, +} + +/// Complete fault catalog for a circuit + noise model. +/// +/// Each location is an independent physical fault mechanism. +/// Each alternative within a location is one possible Pauli error +/// (for depolarizing) or outcome flip (for measurement/prep). +/// +/// Probability model (independent mechanisms): +/// +/// For location i with k_i alternatives: +/// - `channel_probability` = p_i (total probability mechanism fires) +/// - `no_fault_probability` = 1 - p_i +/// - `conditional_probability` = 1/k_i (uniform alternative choice) +/// - `absolute_probability` = p_i / k_i (marginal alternative probability) +/// +/// Full-circuit configuration probability for "alternative j at location i, +/// no fault at all other locations": +/// P = (p_i / k_i) * product_{m != i} (1 - p_m) +#[derive(Clone, Debug)] +pub struct FaultCatalog { + pub locations: Vec, +} + +/// One yielded configuration from `fault_configurations(k)`. +#[derive(Clone, Debug)] +pub struct FaultConfiguration { + /// Indices into `catalog.locations` for the k selected locations. + pub location_indices: Vec, + /// Alternative index chosen within each selected location. + pub alternative_indices: Vec, + /// Combined measurement indices (XOR parity across selected alternatives). + pub affected_measurements: Vec, + /// Combined detector indices (XOR parity). + pub affected_detectors: Vec, + /// Combined observable indices (XOR parity). + pub affected_observables: Vec, + /// Combined tracked-operator indices (XOR parity). + pub affected_tracked_ops: Vec, + /// Product of selected alternatives' absolute_probability. + pub selected_probability: f64, + /// selected_probability * product of unselected locations' no_fault_probability. + pub configuration_probability: f64, +} + +impl FaultCatalog { + /// Lazily iterate all k-fault configurations. + /// + /// Each yielded `FaultConfiguration` represents exactly k distinct locations + /// firing, with one alternative chosen per location. Effects are combined by + /// XOR parity. Probabilities follow the independent-mechanism model. + /// + /// For k=0: yields one no-fault event. + pub fn fault_configurations(&self, k: usize) -> FaultConfigurationIter<'_> { + FaultConfigurationIter::new(self, k) + } +} + +/// Internal cursor for k-fault configuration iteration. +/// +/// Holds the combination/alternative state machine. Shared by both +/// `FaultConfigurationIter` (borrowed) and `OwnedFaultConfigIter` (owned). +struct FaultConfigCursor { + k: usize, + combo: Vec, + alt_indices: Vec, + alt_counts: Vec, + started: bool, + done: bool, +} + +impl FaultConfigCursor { + fn new(num_locations: usize, k: usize, alt_count_fn: impl Fn(usize) -> usize) -> Self { + if k == 0 || k > num_locations { + return Self { + k, + combo: Vec::new(), + alt_indices: Vec::new(), + alt_counts: Vec::new(), + started: false, + done: k > num_locations && k > 0, + }; + } + let combo: Vec = (0..k).collect(); + let alt_counts: Vec = combo.iter().map(|&i| alt_count_fn(i)).collect(); + let alt_indices = vec![0usize; k]; + Self { + k, + combo, + alt_indices, + alt_counts, + started: false, + done: false, + } + } + + /// Advance to the next state. Returns true if a new valid state exists. + fn advance(&mut self, num_locations: usize, alt_count_fn: impl Fn(usize) -> usize) -> bool { + // Try advancing alternatives (mixed-radix counter) + for i in (0..self.k).rev() { + self.alt_indices[i] += 1; + if self.alt_indices[i] < self.alt_counts[i] { + return true; + } + self.alt_indices[i] = 0; + } + // Try advancing combination + let mut i = self.k; + while i > 0 { + i -= 1; + self.combo[i] += 1; + if self.combo[i] <= num_locations - self.k + i { + for j in (i + 1)..self.k { + self.combo[j] = self.combo[j - 1] + 1; + } + for j in 0..self.k { + self.alt_counts[j] = alt_count_fn(self.combo[j]); + self.alt_indices[j] = 0; + } + return true; + } + } + false + } + + /// Build a FaultConfiguration from the current cursor state + catalog data. + fn build(&self, catalog: &FaultCatalog) -> FaultConfiguration { + if self.k == 0 { + let no_fault_prob: f64 = catalog + .locations + .iter() + .map(|l| l.no_fault_probability) + .product(); + return FaultConfiguration { + location_indices: Vec::new(), + alternative_indices: Vec::new(), + affected_measurements: Vec::new(), + affected_detectors: Vec::new(), + affected_observables: Vec::new(), + affected_tracked_ops: Vec::new(), + selected_probability: 1.0, + configuration_probability: no_fault_prob, + }; + } + + let mut meas_set = std::collections::BTreeSet::new(); + let mut det_set = std::collections::BTreeSet::new(); + let mut obs_set = std::collections::BTreeSet::new(); + let mut tracked_op_set = std::collections::BTreeSet::new(); + let mut selected_prob = 1.0; + + for i in 0..self.k { + let loc = &catalog.locations[self.combo[i]]; + let alt = &loc.faults[self.alt_indices[i]]; + selected_prob *= alt.absolute_probability; + for &m in &alt.affected_measurements { + if !meas_set.remove(&m) { + meas_set.insert(m); + } + } + for &d in &alt.affected_detectors { + if !det_set.remove(&d) { + det_set.insert(d); + } + } + for &o in &alt.affected_observables { + if !obs_set.remove(&o) { + obs_set.insert(o); + } + } + for &op in &alt.affected_tracked_ops { + if !tracked_op_set.remove(&op) { + tracked_op_set.insert(op); + } + } + } + + let selected_set: std::collections::BTreeSet = self.combo.iter().copied().collect(); + let unselected_no_fault: f64 = catalog + .locations + .iter() + .enumerate() + .filter(|(i, _)| !selected_set.contains(i)) + .map(|(_, loc)| loc.no_fault_probability) + .product(); + + FaultConfiguration { + location_indices: self.combo.clone(), + alternative_indices: self.alt_indices.clone(), + affected_measurements: meas_set.into_iter().collect(), + affected_detectors: det_set.into_iter().collect(), + affected_observables: obs_set.into_iter().collect(), + affected_tracked_ops: tracked_op_set.into_iter().collect(), + selected_probability: selected_prob, + configuration_probability: selected_prob * unselected_no_fault, + } + } + + /// Drive the iterator: yield next configuration or None. + fn next_config(&mut self, catalog: &FaultCatalog) -> Option { + if self.done { + return None; + } + if self.k == 0 { + self.done = true; + return Some(self.build(catalog)); + } + if !self.started { + self.started = true; + return Some(self.build(catalog)); + } + let n = catalog.locations.len(); + if self.advance(n, |i| catalog.locations[i].faults.len()) { + Some(self.build(catalog)) + } else { + self.done = true; + None + } + } +} + +/// Lazy iterator over k-fault configurations (borrows catalog). +pub struct FaultConfigurationIter<'a> { + catalog: &'a FaultCatalog, + cursor: FaultConfigCursor, +} + +impl<'a> FaultConfigurationIter<'a> { + fn new(catalog: &'a FaultCatalog, k: usize) -> Self { + let cursor = FaultConfigCursor::new(catalog.locations.len(), k, |i| { + catalog.locations[i].faults.len() + }); + Self { catalog, cursor } + } +} + +impl<'a> Iterator for FaultConfigurationIter<'a> { + type Item = FaultConfiguration; + fn next(&mut self) -> Option { + self.cursor.next_config(self.catalog) + } +} + +/// Owned k-fault configuration iterator (no lifetime borrows). +/// Suitable for FFI / PyO3 where lifetimes are not expressible. +pub struct OwnedFaultConfigIter { + catalog: FaultCatalog, + cursor: FaultConfigCursor, +} + +impl OwnedFaultConfigIter { + /// Create from an owned catalog clone. + pub fn new(catalog: FaultCatalog, k: usize) -> Self { + let cursor = FaultConfigCursor::new(catalog.locations.len(), k, |i| { + catalog.locations[i].faults.len() + }); + Self { catalog, cursor } + } +} + +impl Iterator for OwnedFaultConfigIter { + type Item = FaultConfiguration; + fn next(&mut self) -> Option { + self.cursor.next_config(&self.catalog) + } +} + +/// Build a fault catalog from a TickCircuit and noise parameters. +/// +/// Returns per-location, per-alternative fault data including Pauli labels, +/// affected detectors, observables, tracked operators, and probability fields. +/// +/// Reads detector/observable metadata and tracked-operator annotations +/// from the circuit when present. +pub fn build_fault_catalog( + tc: &TickCircuit, + noise: &StochasticNoiseParams, +) -> Result { + validate_tick_circuit(tc)?; + let (gates, meas_positions) = flatten_tick_circuit(tc); + + // Parse detector/DEM-output records for measurement→detector/op mapping + let det_records = parse_detector_records(tc); + let obs_records = parse_observable_records(tc); + let tracked_op_annotations = parse_tracked_operator_annotations(tc); + let num_meas = tc + .get_meta("num_measurements") + .and_then(|a| { + if let pecos_quantum::Attribute::String(s) = a { + s.parse::().ok() + } else { + None + } + }) + .unwrap_or_else(|| meas_positions.len()); + + let mut locations = Vec::new(); + + // Track original tick/gate indices through the flattened gate list + let mut tick_gate_map: Vec<(usize, usize)> = Vec::new(); + for (tick_idx, tick) in tc.ticks().iter().enumerate() { + for (gate_idx, _gate) in tick.gates().iter().enumerate() { + tick_gate_map.push((tick_idx, gate_idx)); + } + } + + // Re-walk the flattened gate list (same order as build_fault_table) + // but record location metadata and Pauli labels + let mut flat_idx_to_tick_gate: Vec<(usize, usize, GateType, Vec)> = Vec::new(); + { + let mut orig_idx = 0; + for tick in tc.ticks() { + for gate in tick.gates() { + let qs: Vec = gate.qubits.iter().map(|q| q.index()).collect(); + let is_mz = is_supported_measurement_gate(gate.gate_type); + let is_2q = is_standard_2q_clifford_gate(gate.gate_type); + let (tick_idx, gate_idx) = tick_gate_map[orig_idx]; + + if is_mz && qs.len() > 1 { + for &q in &qs { + flat_idx_to_tick_gate.push((tick_idx, gate_idx, gate.gate_type, vec![q])); + } + } else if is_2q && qs.len() > 2 { + for pair in qs.chunks(2).filter(|c| c.len() == 2) { + flat_idx_to_tick_gate.push(( + tick_idx, + gate_idx, + gate.gate_type, + vec![pair[0], pair[1]], + )); + } + } else if qs.len() > 1 && !is_2q && !is_mz { + for &q in &qs { + flat_idx_to_tick_gate.push((tick_idx, gate_idx, gate.gate_type, vec![q])); + } + } else { + flat_idx_to_tick_gate.push((tick_idx, gate_idx, gate.gate_type, qs)); + } + orig_idx += 1; + } + } + } + + let pauli_types = [PauliType::X, PauliType::Y, PauliType::Z]; + + for (loc_idx, loc) in gates.iter().enumerate() { + let (tick_idx, gate_idx, gate_type, ref qubits) = flat_idx_to_tick_gate[loc_idx]; + + match loc.gate_type { + gate_type + if is_standard_1q_clifford_gate(gate_type) + && noise.p1 > 0.0 + && !loc.qubits.is_empty() => + { + let q = loc.qubits[0]; + let num_alts = 3; + let mut faults = Vec::with_capacity(num_alts); + for &pt in &pauli_types { + let effect = propagate_single_effect( + pt, + q, + loc_idx + 1, + &gates, + &meas_positions, + &tracked_op_annotations, + ); + let pauli = pauli_type_to_string(pt, q); + let (affected, dets, obs, tracked) = + catalog_effect_parts(effect, &det_records, &obs_records, num_meas); + faults.push(FaultAlternative { + kind: FaultKind::Pauli, + pauli: Some(pauli), + affected_measurements: affected, + affected_detectors: dets, + affected_observables: obs, + affected_tracked_ops: tracked, + conditional_probability: 1.0 / num_alts as f64, + absolute_probability: noise.p1 / num_alts as f64, + }); + } + // Include all locations with nonzero channel probability (even no-effect ones) + let num_alts = faults.len(); + locations.push(FaultLocation { + tick: tick_idx, + gate_index: gate_idx, + gate_type, + qubits: qubits.clone(), + channel: FaultChannel::P1, + channel_probability: noise.p1, + no_fault_probability: 1.0 - noise.p1, + num_alternatives: num_alts, + faults, + }); + } + + gate_type + if is_standard_2q_clifford_gate(gate_type) + && noise.p2 > 0.0 + && loc.qubits.len() >= 2 => + { + let (q1, q2) = (loc.qubits[0], loc.qubits[1]); + let num_alts = 15; + let mut faults = Vec::with_capacity(num_alts); + + // 9 two-qubit pairs + for &p1 in &pauli_types { + for &p2 in &pauli_types { + let effect = propagate_pair_effect( + p1, + q1, + p2, + q2, + loc_idx + 1, + &gates, + &meas_positions, + &tracked_op_annotations, + ); + let pauli = pauli_pair_to_string(p1, q1, p2, q2); + let (affected, dets, obs, tracked) = + catalog_effect_parts(effect, &det_records, &obs_records, num_meas); + faults.push(FaultAlternative { + kind: FaultKind::Pauli, + pauli: Some(pauli), + affected_measurements: affected, + affected_detectors: dets, + affected_observables: obs, + affected_tracked_ops: tracked, + conditional_probability: 1.0 / num_alts as f64, + absolute_probability: noise.p2 / num_alts as f64, + }); + } + } + // 6 single-qubit (PI and IP) + for &p in &pauli_types { + let effect = propagate_single_effect( + p, + q1, + loc_idx + 1, + &gates, + &meas_positions, + &tracked_op_annotations, + ); + let pauli = pauli_type_to_string(p, q1); + let (affected, dets, obs, tracked) = + catalog_effect_parts(effect, &det_records, &obs_records, num_meas); + faults.push(FaultAlternative { + kind: FaultKind::Pauli, + pauli: Some(pauli), + affected_measurements: affected, + affected_detectors: dets, + affected_observables: obs, + affected_tracked_ops: tracked, + conditional_probability: 1.0 / num_alts as f64, + absolute_probability: noise.p2 / num_alts as f64, + }); + + let effect = propagate_single_effect( + p, + q2, + loc_idx + 1, + &gates, + &meas_positions, + &tracked_op_annotations, + ); + let pauli = pauli_type_to_string(p, q2); + let (affected, dets, obs, tracked) = + catalog_effect_parts(effect, &det_records, &obs_records, num_meas); + faults.push(FaultAlternative { + kind: FaultKind::Pauli, + pauli: Some(pauli), + affected_measurements: affected, + affected_detectors: dets, + affected_observables: obs, + affected_tracked_ops: tracked, + conditional_probability: 1.0 / num_alts as f64, + absolute_probability: noise.p2 / num_alts as f64, + }); + } + let n_alts = faults.len(); + locations.push(FaultLocation { + tick: tick_idx, + gate_index: gate_idx, + gate_type, + qubits: qubits.clone(), + channel: FaultChannel::P2, + channel_probability: noise.p2, + no_fault_probability: 1.0 - noise.p2, + num_alternatives: n_alts, + faults, + }); + } + + GateType::PZ | GateType::QAlloc if noise.p_prep > 0.0 && !loc.qubits.is_empty() => { + let q = loc.qubits[0]; + let effect = propagate_single_effect( + PauliType::X, + q, + loc_idx + 1, + &gates, + &meas_positions, + &tracked_op_annotations, + ); + let (affected, dets, obs, tracked) = + catalog_effect_parts(effect, &det_records, &obs_records, num_meas); + locations.push(FaultLocation { + tick: tick_idx, + gate_index: gate_idx, + gate_type, + qubits: qubits.clone(), + channel: FaultChannel::PPrep, + channel_probability: noise.p_prep, + no_fault_probability: 1.0 - noise.p_prep, + num_alternatives: 1, + faults: vec![FaultAlternative { + kind: FaultKind::PrepFlip, + pauli: None, + affected_measurements: affected, + affected_detectors: dets, + affected_observables: obs, + affected_tracked_ops: tracked, + conditional_probability: 1.0, + absolute_probability: noise.p_prep, + }], + }); + } + + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked + if noise.p_meas > 0.0 => + { + if let Some(&meas_idx) = meas_positions.get(&loc_idx) { + let affected = vec![meas_idx]; + let dets = measurements_to_detectors(&affected, &det_records, num_meas); + let obs = measurements_to_observables(&affected, &obs_records, num_meas); + locations.push(FaultLocation { + tick: tick_idx, + gate_index: gate_idx, + gate_type, + qubits: qubits.clone(), + channel: FaultChannel::PMeas, + channel_probability: noise.p_meas, + no_fault_probability: 1.0 - noise.p_meas, + num_alternatives: 1, + faults: vec![FaultAlternative { + kind: FaultKind::MeasurementFlip, + pauli: None, + affected_measurements: affected, + affected_detectors: dets, + affected_observables: obs, + affected_tracked_ops: Vec::new(), + conditional_probability: 1.0, + absolute_probability: noise.p_meas, + }], + }); + } + } + + _ => {} + } + } + + Ok(FaultCatalog { locations }) +} + +// ---- Helpers for fault catalog ---- + +fn pauli_type_to_pauli(pt: PauliType) -> Pauli { + match pt { + PauliType::X => Pauli::X, + PauliType::Y => Pauli::Y, + PauliType::Z => Pauli::Z, + } +} + +fn pauli_type_to_string(pt: PauliType, qubit: usize) -> PauliString { + PauliString::with_phase_and_paulis( + pecos_core::QuarterPhase::PlusOne, + vec![(pauli_type_to_pauli(pt), QubitId(qubit))], + ) +} + +fn pauli_pair_to_string(p1: PauliType, q1: usize, p2: PauliType, q2: usize) -> PauliString { + PauliString::with_phase_and_paulis( + pecos_core::QuarterPhase::PlusOne, + vec![ + (pauli_type_to_pauli(p1), QubitId(q1)), + (pauli_type_to_pauli(p2), QubitId(q2)), + ], + ) +} + +fn parse_records_from_meta(tc: &TickCircuit, key: &str) -> Vec> { + let json = match tc.get_meta(key) { + Some(pecos_quantum::Attribute::String(s)) => s, + _ => return Vec::new(), + }; + parse_records_array_list(&json) +} + +fn parse_detector_records(tc: &TickCircuit) -> Vec> { + parse_records_from_meta(tc, "detectors") +} + +fn parse_observable_records(tc: &TickCircuit) -> Vec> { + parse_records_from_meta(tc, "observables") +} + +fn parse_tracked_operator_annotations(tc: &TickCircuit) -> Vec { + tc.annotations() + .iter() + .filter(|ann| matches!(ann.kind, AnnotationKind::Operator)) + .map(|ann| { + let mut pauli = ann.pauli.clone(); + pauli.set_phase(pecos_core::QuarterPhase::PlusOne); + pauli + }) + .collect() +} + +fn tracked_ops_flipped_by(prop: &PauliProp, tracked_ops: &[PauliString]) -> Vec { + tracked_ops + .iter() + .enumerate() + .filter_map(|(idx, tracked_op)| { + let mut parity = false; + for &(pauli, qubit) in tracked_op.paulis() { + let q = qubit.index(); + match pauli { + Pauli::X => parity ^= prop.contains_z(q), + Pauli::Y => parity ^= prop.contains_x(q) ^ prop.contains_z(q), + Pauli::Z => parity ^= prop.contains_x(q), + Pauli::I => {} + } + } + parity.then_some(idx) + }) + .collect() +} + +/// Simple parser for `[{"records": [...]}, ...]` JSON without serde_json. +fn parse_records_array_list(json: &str) -> Vec> { + let json = json.trim(); + if json.is_empty() || json == "[]" { + return Vec::new(); + } + let mut results = Vec::new(); + // Find each "records": [...] within the JSON + let mut search_from = 0; + while let Some(pos) = json[search_from..].find("\"records\"") { + let pos = search_from + pos; + let rest = &json[pos..]; + if let Some(arr_start) = rest.find('[') { + if let Some(arr_end) = rest[arr_start..].find(']') { + let arr_str = &rest[arr_start + 1..arr_start + arr_end]; + let nums: Vec = arr_str + .split(',') + .filter_map(|s| s.trim().parse().ok()) + .collect(); + results.push(nums); + search_from = pos + arr_start + arr_end + 1; + } else { + break; + } + } else { + break; + } + } + results +} + +/// Map measurement effects to detector effects via record XOR. +fn measurements_to_detectors( + affected_meas: &[usize], + det_records: &[Vec], + num_meas: usize, +) -> Vec { + let mut fired = Vec::new(); + for (det_idx, records) in det_records.iter().enumerate() { + let mut parity = 0u8; + for &rec in records { + let abs_idx = (num_meas as i32 + rec) as usize; + if affected_meas.contains(&abs_idx) { + parity ^= 1; + } + } + if parity != 0 { + fired.push(det_idx); + } + } + fired +} + +/// Map measurement effects to observable effects via record XOR. +fn measurements_to_observables( + affected_meas: &[usize], + obs_records: &[Vec], + num_meas: usize, +) -> Vec { + let mut fired = Vec::new(); + for (obs_idx, records) in obs_records.iter().enumerate() { + let mut parity = 0u8; + for &rec in records { + let abs_idx = (num_meas as i32 + rec) as usize; + if affected_meas.contains(&abs_idx) { + parity ^= 1; + } + } + if parity != 0 { + fired.push(obs_idx); + } + } + fired +} + +fn catalog_effect_parts( + effect: PropagatedFaultEffect, + det_records: &[Vec], + obs_records: &[Vec], + num_meas: usize, +) -> (Vec, Vec, Vec, Vec) { + let affected: Vec = effect.affected_measurements.into_iter().collect(); + let dets = measurements_to_detectors(&affected, det_records, num_meas); + let obs = measurements_to_observables(&affected, obs_records, num_meas); + (affected, dets, obs, effect.affected_tracked_ops) +} + +// ============================================================================ +// Shared symbolic simulation helper +// ============================================================================ + +/// Run `SymbolicSparseStab` through a `TickCircuit` with proper PZ (reset) +/// semantics, returning the `MeasurementHistory` with correct cross-reset +/// correlations. +/// +/// Iterates tick-by-tick to match the TickCircuit's measurement numbering +/// (which detector/DEM-output record indices reference). +/// +/// Errors on unsupported gates with tick/gate/qubit context (same gate set +/// as [`build_fault_table`]). +pub fn symbolic_measurement_history( + tc: &TickCircuit, +) -> Result { + use pecos_simulators::SymbolicSparseStab; + + let num_qubits = tc + .ticks() + .iter() + .flat_map(|t| t.gates().iter()) + .flat_map(|g| g.qubits.iter()) + .map(|q| q.index() + 1) + .max() + .unwrap_or(0); + + let mut sim = SymbolicSparseStab::new(num_qubits); + + for (tick_idx, tick) in tc.ticks().iter().enumerate() { + for (gate_idx, gate) in tick.gates().iter().enumerate() { + let qs: Vec = gate.qubits.iter().map(|q| q.index()).collect(); + + match gate.gate_type { + GateType::PZ | GateType::QAlloc => { + for &q in &qs { + sim.pz(q); + } + } + GateType::H => { + sim.h(&qs); + } + GateType::X => { + sim.x(&qs); + } + GateType::Y => { + sim.y(&qs); + } + GateType::Z => { + sim.z(&qs); + } + GateType::SZ => { + sim.sz(&qs); + } + GateType::SZdg => { + sim.szdg(&qs); + } + GateType::SX => { + sim.sx(&qs); + } + GateType::SXdg => { + sim.sxdg(&qs); + } + GateType::SY => { + sim.sy(&qs); + } + GateType::SYdg => { + sim.sydg(&qs); + } + GateType::F => { + sim.sx(&qs); + sim.sz(&qs); + } + GateType::Fdg => { + sim.szdg(&qs); + sim.sxdg(&qs); + } + GateType::CX => { + let pairs = symbolic_pairs(&qs); + sim.cx(&pairs); + } + GateType::CY => { + sim.cy(&symbolic_pairs(&qs)); + } + GateType::CZ => { + sim.cz(&symbolic_pairs(&qs)); + } + GateType::SXX => { + sim.sxx(&symbolic_pairs(&qs)); + } + GateType::SXXdg => { + sim.sxxdg(&symbolic_pairs(&qs)); + } + GateType::SYY => { + sim.syy(&symbolic_pairs(&qs)); + } + GateType::SYYdg => { + sim.syydg(&symbolic_pairs(&qs)); + } + GateType::SZZ => { + sim.szz(&symbolic_pairs(&qs)); + } + GateType::SZZdg => { + sim.szzdg(&symbolic_pairs(&qs)); + } + GateType::SWAP => { + sim.swap(&symbolic_pairs(&qs)); + } + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked => { + sim.mz(&qs); + } + GateType::I + | GateType::Idle + | GateType::QFree + | GateType::MeasCrosstalkGlobalPayload + | GateType::MeasCrosstalkLocalPayload + | GateType::PauliOperatorMeta => {} + other => { + return Err(UnsupportedGateError { + gate_type: other, + tick: tick_idx, + gate_in_tick: gate_idx, + qubits: qs, + }); + } + } + } + } + + Ok(sim.measurement_history().clone()) +} + +fn symbolic_pairs(qs: &[usize]) -> Vec<(usize, usize)> { + qs.chunks(2) + .filter(|c| c.len() == 2) + .map(|c| (c[0], c[1])) + .collect() +} + +// ============================================================================ +// Raw Measurement Plan: geometric/O(fired) columnar sampling +// ============================================================================ + +/// Zero out bits beyond `shots` in the final word of each column. +fn mask_partial_final_word(columns: &mut [Vec], shots: usize) { + let remainder = shots % 64; + if remainder == 0 { + return; + } + let mask = (1u64 << remainder) - 1; + for col in columns.iter_mut() { + if let Some(last) = col.last_mut() { + *last &= mask; + } + } +} + +/// Columnar raw-measurement result with r-source access. +/// +/// The measurement columns are the final output (base XOR faults). +/// The `r_columns` field holds the latent random source columns that feed +/// into the ideal measurement dependency graph. +pub struct RawSampleResult { + /// Final measurement columns: `columns[meas_idx][word_idx]`, bit i = shot word*64+i. + /// Bits beyond `shots` in the final word are always zero. + pub columns: Vec>, + /// Latent r-source columns (one per Random measurement kind). + /// Bits beyond `shots` in the final word are always zero. + pub r_columns: Vec>, + /// Measurement index that introduced each r-source. + /// `r_source_measurements[k]` is the measurement index for `r_columns[k]`. + pub r_source_measurements: Vec, + pub shots: usize, +} + +/// A compiled plan for sampling raw measurements from a stochastic circuit. +/// +/// Combines: +/// - **r-sources** (p=0.5): non-deterministic measurement variables from the +/// ideal dependency graph. These fan out through Copy/Computed relationships. +/// - **Physical mechanisms**: depolarizing gate faults, prep faults, +/// measurement flips. These do NOT fan out through ideal dependencies. +/// +/// Physical mechanisms are sampled using geometric skip (O(fired events) per +/// mechanism), matching the DEM sampler's performance characteristics. +pub struct RawMeasurementPlan { + pub num_measurements: usize, + kinds: Vec, + pub mechanisms: Vec, + /// Precomputed 1/ln(1-p) for geometric skip sampling, one per mechanism. + inv_log_1_minus_p: Vec, +} + +impl RawMeasurementPlan { + /// Build a plan from a measurement history and fault mechanisms. + pub fn new(history: &MeasurementHistory, mechanisms: Vec) -> Self { + let kinds = MeasurementKind::from_history(history); + let inv_log_1_minus_p = mechanisms + .iter() + .map(|m| { + let log_1_minus_p = (1.0 - m.probability).ln(); + if log_1_minus_p.abs() < f64::EPSILON { + 0.0 + } else { + 1.0 / log_1_minus_p + } + }) + .collect(); + Self { + num_measurements: kinds.len(), + kinds, + mechanisms, + inv_log_1_minus_p, + } + } + + /// Sample raw measurements using geometric skip for physical faults. + /// + /// Returns a `SampleResult` for compatibility with existing code. + /// For r-event access, use [`sample_raw`]. + pub fn sample(&self, shots: usize, seed: u64) -> SampleResult { + let raw = self.sample_raw(shots, seed); + SampleResult::new(raw.columns, shots) + } + + /// Sample raw measurements with r-source column access. + /// + /// Physical mechanisms use geometric skip: O(p * shots) RNG calls per + /// mechanism, not O(shots). For typical QEC noise (p ~ 0.005, 20k shots), + /// this is ~100 firings per mechanism vs 20000 iterations. + pub fn sample_raw(&self, shots: usize, seed: u64) -> RawSampleResult { + if shots == 0 { + let r_source_measurements = self.r_source_indices(); + return RawSampleResult { + columns: vec![Vec::new(); self.num_measurements], + r_columns: vec![Vec::new(); r_source_measurements.len()], + r_source_measurements, + shots: 0, + }; + } + + let num_words = shots.div_ceil(64); + + // 1. Sample base values (r-sources + constants) and capture r columns + let mut rng_base = PecosRng::seed_from_u64(seed); + let (mut columns, mut r_columns) = self.sample_base(num_words, &mut rng_base); + + // 2. Overlay physical faults using geometric skip + if !self.mechanisms.is_empty() { + let mut rng_fault = PecosRng::seed_from_u64(seed.wrapping_add(1)); + self.overlay_faults_geometric(shots, &mut columns, &mut rng_fault); + } + + // 3. Mask partial final word so bits beyond `shots` are always zero + mask_partial_final_word(&mut columns, shots); + mask_partial_final_word(&mut r_columns, shots); + + RawSampleResult { + columns, + r_columns, + r_source_measurements: self.r_source_indices(), + shots, + } + } + + /// Returns the measurement indices that correspond to r-sources (Random kinds). + fn r_source_indices(&self) -> Vec { + self.kinds + .iter() + .enumerate() + .filter_map(|(i, k)| { + if matches!(k, MeasurementKind::Random) { + Some(i) + } else { + None + } + }) + .collect() + } + + /// Sample base measurement values from r-sources and constants. + /// Returns (measurement_columns, r_source_columns). + fn sample_base(&self, num_words: usize, rng: &mut PecosRng) -> (Vec>, Vec>) { + let mut columns: Vec> = Vec::with_capacity(self.num_measurements); + let mut r_columns: Vec> = Vec::new(); + + for kind in &self.kinds { + match kind { + MeasurementKind::Fixed(value) => { + let fill = if *value { !0u64 } else { 0u64 }; + columns.push(vec![fill; num_words]); + } + MeasurementKind::Random => { + let mut col = vec![0u64; num_words]; + for word in &mut col { + *word = rng.next_u64(); + } + r_columns.push(col.clone()); + columns.push(col); + } + MeasurementKind::Copy(src) => { + columns.push(columns[*src].clone()); + } + MeasurementKind::CopyFlipped(src) => { + let flipped: Vec = columns[*src].iter().map(|w| !w).collect(); + columns.push(flipped); + } + MeasurementKind::Computed { deps, flip } => { + let init = if *flip { !0u64 } else { 0u64 }; + let mut col = vec![init; num_words]; + for &dep in deps { + for (w, &d) in col.iter_mut().zip(columns[dep].iter()) { + *w ^= d; + } + } + columns.push(col); + } + } + } + + (columns, r_columns) + } + + /// Overlay physical faults using geometric skip sampling. + /// + /// For each mechanism with probability p: + /// - Precomputed `inv_log = 1/ln(1-p)` + /// - Sample `skip = floor(ln(U) * inv_log)` to jump to next fired shot + /// - At fired shot: choose uniform alternative, XOR affected measurements + /// + /// Complexity: O(p * shots) per mechanism (geometric = O(fired events)). + fn overlay_faults_geometric(&self, shots: usize, columns: &mut [Vec], rng: &mut PecosRng) { + for (mech_idx, mechanism) in self.mechanisms.iter().enumerate() { + let inv_log = self.inv_log_1_minus_p[mech_idx]; + let p = mechanism.probability; + let num_alts = mechanism.alternatives.len(); + + // p=1: every shot fires (handle before inv_log check since inv_log=0 for p=1) + if p >= 1.0 { + for shot in 0..shots { + let word_idx = shot / 64; + let bit_idx = shot % 64; + let mask = 1u64 << bit_idx; + let alt_idx = if num_alts == 1 { + 0 + } else { + rng.random_range(0..num_alts) + }; + for &meas_idx in &mechanism.alternatives[alt_idx] { + columns[meas_idx][word_idx] ^= mask; + } + } + continue; + } + + // Skip p=0 mechanisms (inv_log=0 means p≈0 or exactly 0) + if p == 0.0 || inv_log == 0.0 { + continue; + } + + // Geometric skip sampling: O(fired events) + let mut shot: usize = 0; + while shot < shots { + // Sample skip distance + #[allow(clippy::cast_precision_loss)] + let u = (rng.next_u64() as f64) / (u64::MAX as f64); + let u = if u == 0.0 { f64::MIN_POSITIVE } else { u }; + #[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)] + let skip = (u.ln() * inv_log).floor() as usize; + + shot += skip; + if shot >= shots { + break; + } + + // This shot fires — choose alternative and XOR + let word_idx = shot / 64; + let bit_idx = shot % 64; + let mask = 1u64 << bit_idx; + + let alt_idx = if num_alts == 1 { + 0 + } else { + rng.random_range(0..num_alts) + }; + for &meas_idx in &mechanism.alternatives[alt_idx] { + if meas_idx < columns.len() { + columns[meas_idx][word_idx] ^= mask; + } + } + + shot += 1; + } + } + } +} + +#[cfg(test)] +mod tests { + use super::*; + + /// Build a minimal TickCircuit: PZ(0) H(0) CX(0,1) H(0) MZ(0) PZ(0) H(0) CX(0,1) H(0) MZ(0) + fn two_round_x_check() -> TickCircuit { + let mut tc = TickCircuit::new(); + // Round 1 + tc.tick().h(&[QubitId(0)]); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.tick().pz(&[QubitId(0)]); + // Round 2 + tc.tick().h(&[QubitId(0)]); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc + } + + #[test] + fn test_meas_fault_affects_single_measurement() { + let tc = two_round_x_check(); + let noise = StochasticNoiseParams { + p1: 0.0, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }; + let mechanisms = build_fault_table(&tc, &noise).unwrap(); + + // Should have exactly 2 measurement mechanisms (one per MZ), + // each with 1 alternative that flips that measurement. + assert_eq!(mechanisms.len(), 2); + assert_eq!(mechanisms[0].alternatives, vec![vec![0]]); + assert_eq!(mechanisms[1].alternatives, vec![vec![1]]); + assert!((mechanisms[0].probability - 0.01).abs() < 1e-10); + } + + #[test] + fn test_prep_fault_reaches_next_measurement_only() { + let tc = two_round_x_check(); + let noise = StochasticNoiseParams { + p1: 0.0, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.01, + }; + let mechanisms = build_fault_table(&tc, &noise).unwrap(); + + // PZ(0) before round 2: single alternative affecting only m1 + let round2_prep = mechanisms.iter().find(|m| m.alternatives == vec![vec![1]]); + assert!( + round2_prep.is_some(), + "PZ before round 2 should produce mechanism affecting m1" + ); + } + + #[test] + fn test_prep_fault_does_not_cross_pz() { + let tc = two_round_x_check(); + let noise = StochasticNoiseParams { + p1: 0.0, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.01, + }; + let mechanisms = build_fault_table(&tc, &noise).unwrap(); + + // No alternative should affect BOTH m0 and m1 (PZ between rounds absorbs) + for m in &mechanisms { + for alt in &m.alternatives { + assert!( + !(alt.contains(&0) && alt.contains(&1)), + "Fault alternative crosses PZ boundary: {:?}", + alt + ); + } + } + } + + // ---- Direct propagation tests using propagate_single ---- + + #[test] + fn test_propagate_x_before_cx_reaches_target_mz() { + // Circuit: CX(0,1) MZ(1) + // X on q0 before CX: CX maps XI → XX → MZ(q1) sees X → flips + let mut tc = TickCircuit::new(); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(1)]); + + let (gates, meas_pos) = flatten_tick_circuit(&tc); + let affected = propagate_single(PauliType::X, 0, 0, &gates, &meas_pos); + assert_eq!( + affected, + BTreeSet::from([0]), + "X on q0 before CX(0,1) MZ(1) should flip m0" + ); + } + + #[test] + fn test_propagate_z_before_cx_stays_on_control() { + // Circuit: CX(0,1) MZ(1) + // Z on q0 before CX: CX maps ZI → ZI → MZ(q1) sees I → no flip + let mut tc = TickCircuit::new(); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(1)]); + + let (gates, meas_pos) = flatten_tick_circuit(&tc); + let affected = propagate_single(PauliType::Z, 0, 0, &gates, &meas_pos); + assert!( + affected.is_empty(), + "Z on q0 before CX(0,1) should not reach MZ(q1)" + ); + } + + #[test] + fn test_propagate_x_on_target_unchanged_by_cx() { + // Circuit: CX(0,1) MZ(1) + // X on q1 before CX: CX maps IX → IX → MZ(q1) sees X → flips + let mut tc = TickCircuit::new(); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(1)]); + + let (gates, meas_pos) = flatten_tick_circuit(&tc); + let affected = propagate_single(PauliType::X, 1, 0, &gates, &meas_pos); + assert_eq!(affected, BTreeSet::from([0])); + } + + #[test] + fn test_propagate_z_on_target_spreads_to_control_via_cx() { + // Circuit: CX(0,1) MZ(0) MZ(1) + // Z on q1 before CX: CX maps IZ → ZZ → MZ(q0) sees Z (no flip), MZ(q1) sees Z (no flip) + let mut tc = TickCircuit::new(); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(1)]); + + let (gates, meas_pos) = flatten_tick_circuit(&tc); + let affected = propagate_single(PauliType::Z, 1, 0, &gates, &meas_pos); + assert!( + affected.is_empty(), + "Z errors don't flip Z-basis measurements" + ); + } + + #[test] + fn test_propagate_x_through_h_becomes_z() { + // Circuit: H(0) MZ(0) + // X on q0 at position 0: H maps X→Z → MZ sees Z → no flip + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + + let (gates, meas_pos) = flatten_tick_circuit(&tc); + let affected = propagate_single(PauliType::X, 0, 0, &gates, &meas_pos); + assert!( + affected.is_empty(), + "X through H becomes Z, should not flip MZ" + ); + } + + #[test] + fn test_propagate_z_through_h_becomes_x() { + // Circuit: H(0) MZ(0) + // Z on q0 at position 0: H maps Z→X → MZ sees X → flips + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + + let (gates, meas_pos) = flatten_tick_circuit(&tc); + let affected = propagate_single(PauliType::Z, 0, 0, &gates, &meas_pos); + assert_eq!( + affected, + BTreeSet::from([0]), + "Z through H becomes X, should flip MZ" + ); + } + + #[test] + fn test_propagate_x_absorbed_by_pz() { + // Circuit: PZ(0) MZ(0) + // X on q0 at position 0: PZ absorbs it → MZ sees I → no flip + let mut tc = TickCircuit::new(); + tc.tick().pz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + + let (gates, meas_pos) = flatten_tick_circuit(&tc); + let affected = propagate_single(PauliType::X, 0, 0, &gates, &meas_pos); + assert!(affected.is_empty(), "X should be absorbed by PZ"); + } + + #[test] + fn test_pz_absorbs_all_pauli_components_before_reset() { + // Circuit: PZ(0) H(0) MZ(0) + // Any fault before the reset is absorbed. Faults after the reset still + // propagate through the H according to normal Clifford conjugation. + let mut tc = TickCircuit::new(); + tc.tick().pz(&[QubitId(0)]); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + + let (gates, meas_pos) = flatten_tick_circuit(&tc); + for pauli in [PauliType::X, PauliType::Y, PauliType::Z] { + let affected = propagate_single(pauli, 0, 0, &gates, &meas_pos); + assert!( + affected.is_empty(), + "{pauli:?} before PZ should be absorbed by the reset" + ); + } + + assert!( + propagate_single(PauliType::X, 0, 1, &gates, &meas_pos).is_empty(), + "X after PZ becomes Z through H and should not flip MZ" + ); + assert_eq!( + propagate_single(PauliType::Y, 0, 1, &gates, &meas_pos), + BTreeSet::from([0]), + "Y after PZ keeps an X component through H and should flip MZ" + ); + assert_eq!( + propagate_single(PauliType::Z, 0, 1, &gates, &meas_pos), + BTreeSet::from([0]), + "Z after PZ becomes X through H and should flip MZ" + ); + } + + #[test] + fn test_propagate_x_absorbed_by_mz() { + // Circuit: MZ(0) MZ(0) — X on q0 should flip first MZ only + // (MZ collapses qubit, absorbing the error) + let mut tc = TickCircuit::new(); + tc.tick().mz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + + let (gates, meas_pos) = flatten_tick_circuit(&tc); + let affected = propagate_single(PauliType::X, 0, 0, &gates, &meas_pos); + assert_eq!( + affected, + BTreeSet::from([0]), + "X should flip first MZ only, not second" + ); + } + + #[test] + fn test_propagate_x_check_round_reaches_ancilla_only() { + // X-check pattern: H(0) CX(0,1) CX(0,2) H(0) MZ(0) + // X on q1 (data) at start: CX maps IX→IX on q1 (target stays). + // After H-CX-CX-H, X on q1 doesn't propagate to ancilla. + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().cx(&[(QubitId(0), QubitId(2))]); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + + let (gates, meas_pos) = flatten_tick_circuit(&tc); + + // X on data q1: CX(ctrl=0, tgt=1) doesn't spread X from target to control. + // So X stays on q1, never reaches MZ(q0). + let affected = propagate_single(PauliType::X, 1, 0, &gates, &meas_pos); + assert!( + affected.is_empty(), + "X on data qubit should not reach ancilla MZ in X-check" + ); + + // Z on data q1: CX maps IZ → ZZ (spreads to control q0). + // Then H(q0) maps Z→X on ancilla. MZ(q0) sees X → flips. + let affected = propagate_single(PauliType::Z, 1, 0, &gates, &meas_pos); + assert_eq!( + affected, + BTreeSet::from([0]), + "Z on data should reach ancilla MZ in X-check" + ); + } + + #[test] + fn test_empty_alternative_preserved_for_correct_denominator() { + // H(0); MZ(0): p1 faults are injected AFTER H, directly before MZ. + // The 3 alternatives (X, Y, Z injected between H and MZ): + // X: has X component → flips MZ + // Y: has X component → flips MZ + // Z: commutes with MZ → no flip (empty alternative) + // All 3 must be present so each is chosen with probability 1/3. + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + + let noise = StochasticNoiseParams { + p1: 0.01, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }; + let mechanisms = build_fault_table(&tc, &noise).unwrap(); + + assert_eq!(mechanisms.len(), 1, "one mechanism for the H gate"); + let m = &mechanisms[0]; + assert_eq!( + m.alternatives.len(), + 3, + "all 3 Pauli alternatives must be present" + ); + // Exactly one alternative should be empty (Z between H and MZ commutes) + let empty_count = m.alternatives.iter().filter(|a| a.is_empty()).count(); + assert_eq!( + empty_count, 1, + "Z injected after H commutes with MZ — should be empty no-op alternative" + ); + } + + #[test] + fn test_zero_noise_produces_no_faults() { + let tc = two_round_x_check(); + let noise = StochasticNoiseParams { + p1: 0.0, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }; + let faults = build_fault_table(&tc, &noise).unwrap(); + assert!(faults.is_empty()); + } + + #[test] + fn test_unsupported_gate_rejected_even_with_zero_noise() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().t(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + + // Zero noise — validation runs on raw TickCircuit before anything else + let noise = StochasticNoiseParams { + p1: 0.0, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }; + let result = build_fault_table(&tc, &noise); + assert!(result.is_err(), "T should be rejected"); + let err = result.unwrap_err(); + assert_eq!(err.gate_type, GateType::T); + assert_eq!(err.tick, 1, "T is in tick 1"); + assert_eq!(err.gate_in_tick, 0, "T is gate 0 within that tick"); + assert_eq!(err.qubits, vec![0], "full original qubit list"); + } + + // ---- symbolic_measurement_history tests ---- + + #[test] + fn test_symbolic_history_rejects_unsupported_gate() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().t(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + + let result = symbolic_measurement_history(&tc); + assert!(result.is_err(), "T should be rejected"); + let err = result.unwrap_err(); + assert_eq!(err.gate_type, GateType::T); + assert_eq!(err.tick, 1); + assert_eq!(err.qubits, vec![0]); + } + + #[test] + fn test_symbolic_history_cy_circuit_succeeds() { + // CY(0,1) MZ(1): should not error; CY is a valid Clifford gate + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + let pairs = [(QubitId(0), QubitId(1))]; + tc.tick().cy(&pairs); + tc.tick().mz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(1)]); + + let history = symbolic_measurement_history(&tc); + assert!(history.is_ok(), "CY should be supported"); + assert_eq!(history.unwrap().len(), 2); + } + + #[test] + fn test_symbolic_history_bell_produces_correct_kinds() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(1)]); + + let history = symbolic_measurement_history(&tc).unwrap(); + let kinds = MeasurementKind::from_history(&history); + assert_eq!(kinds.len(), 2); + assert!(matches!(kinds[0], MeasurementKind::Random)); + assert!(matches!(kinds[1], MeasurementKind::Copy(0))); + } + + #[test] + fn test_symbolic_history_reset_breaks_copy_chain_between_rounds() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(1)]); + tc.tick().pz(&[QubitId(0)]); + tc.tick().pz(&[QubitId(1)]); + tc.tick().h(&[QubitId(0)]); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(1)]); + + let history = symbolic_measurement_history(&tc).unwrap(); + let kinds = MeasurementKind::from_history(&history); + assert_eq!(kinds.len(), 4); + assert!(matches!(kinds[0], MeasurementKind::Random)); + assert!(matches!(kinds[1], MeasurementKind::Copy(0))); + assert!( + matches!(kinds[2], MeasurementKind::Random), + "measurement after reset should introduce a fresh random source" + ); + assert!( + !matches!(kinds[2], MeasurementKind::Copy(0)), + "reset must break the copy chain from the first round" + ); + assert!(matches!(kinds[3], MeasurementKind::Copy(2))); + } + + // ---- FaultCatalog tests ---- + + #[test] + fn test_catalog_single_qubit_depolarizing() { + // H(0) MZ(0): p1 fault after H has 3 alternatives + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".to_string()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String("[]".to_string()), + ); + tc.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + + // Should have exactly 1 location (H gate) with 3 alternatives + let h_locs: Vec<_> = catalog + .locations + .iter() + .filter(|l| l.gate_type == GateType::H) + .collect(); + assert_eq!(h_locs.len(), 1); + let loc = &h_locs[0]; + assert_eq!(loc.faults.len(), 3); + assert_eq!(loc.channel, FaultChannel::P1); + assert!((loc.channel_probability - 0.03).abs() < 1e-10); + assert!((loc.no_fault_probability - 0.97).abs() < 1e-10); + assert_eq!(loc.num_alternatives, 3); + + for fault in &loc.faults { + assert_eq!(fault.kind, FaultKind::Pauli); + assert!(fault.pauli.is_some()); + assert!((fault.conditional_probability - 1.0 / 3.0).abs() < 1e-10); + assert!((fault.absolute_probability - 0.01).abs() < 1e-10); + } + } + + #[test] + fn test_catalog_two_qubit_depolarizing() { + // CX(0,1) MZ(0) MZ(1): p2 fault has 15 alternatives + let mut tc = TickCircuit::new(); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(1)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("2".to_string()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String("[]".to_string()), + ); + tc.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let noise = StochasticNoiseParams { + p1: 0.0, + p2: 0.15, + p_meas: 0.0, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + + let cx_locs: Vec<_> = catalog + .locations + .iter() + .filter(|l| l.gate_type == GateType::CX) + .collect(); + assert_eq!(cx_locs.len(), 1); + let loc = &cx_locs[0]; + assert_eq!(loc.faults.len(), 15); + assert_eq!(loc.num_alternatives, 15); + + for fault in &loc.faults { + assert_eq!(fault.kind, FaultKind::Pauli); + assert!(fault.pauli.is_some()); + assert!((fault.conditional_probability - 1.0 / 15.0).abs() < 1e-10); + assert!((fault.absolute_probability - 0.01).abs() < 1e-10); + } + + // Verify 9 two-qubit PauliStrings and 6 single-qubit PauliStrings + let two_term: usize = loc + .faults + .iter() + .filter(|f| f.pauli.as_ref().unwrap().iter_pairs().count() == 2) + .count(); + let one_term: usize = loc + .faults + .iter() + .filter(|f| f.pauli.as_ref().unwrap().iter_pairs().count() == 1) + .count(); + assert_eq!(two_term, 9, "Should have 9 two-qubit Pauli alternatives"); + assert_eq!(one_term, 6, "Should have 6 single-qubit Pauli alternatives"); + } + + #[test] + fn test_catalog_supports_all_traced_qis_clifford_gates() { + let mut tc = TickCircuit::new(); + tc.tick().szdg(&[QubitId(0)]); + tc.tick().sx(&[QubitId(0)]); + tc.tick().sxdg(&[QubitId(1)]); + tc.tick().sy(&[QubitId(0)]); + tc.tick().sydg(&[QubitId(1)]); + tc.tick().f(&[QubitId(0)]); + tc.tick().fdg(&[QubitId(1)]); + tc.tick().cy(&[(QubitId(0), QubitId(1))]); + tc.tick().cz(&[(QubitId(0), QubitId(1))]); + tc.tick().sxx(&[(QubitId(0), QubitId(1))]); + tc.tick().sxxdg(&[(QubitId(0), QubitId(1))]); + tc.tick().syy(&[(QubitId(0), QubitId(1))]); + tc.tick().syydg(&[(QubitId(0), QubitId(1))]); + tc.tick().szz(&[(QubitId(0), QubitId(1))]); + tc.tick().szzdg(&[(QubitId(0), QubitId(1))]); + tc.tick().swap(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(0), QubitId(1)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("2".to_string()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String("[]".to_string()), + ); + tc.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.15, + p_meas: 0.0, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + + for (gate_type, expected_alternatives) in [ + (GateType::SZdg, 3), + (GateType::SX, 3), + (GateType::SXdg, 3), + (GateType::SY, 3), + (GateType::SYdg, 3), + (GateType::F, 3), + (GateType::Fdg, 3), + (GateType::CY, 15), + (GateType::CZ, 15), + (GateType::SXX, 15), + (GateType::SXXdg, 15), + (GateType::SYY, 15), + (GateType::SYYdg, 15), + (GateType::SZZ, 15), + (GateType::SZZdg, 15), + (GateType::SWAP, 15), + ] { + let locations: Vec<_> = catalog + .locations + .iter() + .filter(|loc| loc.gate_type == gate_type) + .collect(); + assert_eq!(locations.len(), 1, "{gate_type:?}"); + assert_eq!( + locations[0].faults.len(), + expected_alternatives, + "{gate_type:?}" + ); + } + } + + #[test] + fn test_catalog_fault_effects_through_new_clifford_gates() { + fn fault_for_pauli<'a>( + loc: &'a FaultLocation, + pauli: &PauliString, + ) -> &'a FaultAlternative { + loc.faults + .iter() + .find(|fault| fault.pauli.as_ref() == Some(pauli)) + .expect("missing expected Pauli fault") + } + + let mut single = TickCircuit::new(); + single.tick().h(&[QubitId(0)]); + single.tick().sy(&[QubitId(0)]); + single.tick().mz(&[QubitId(0)]); + single.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".to_string()), + ); + single.set_meta( + "detectors", + pecos_quantum::Attribute::String("[]".to_string()), + ); + single.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let single_catalog = build_fault_catalog( + &single, + &StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + let h_loc = single_catalog + .locations + .iter() + .find(|loc| loc.gate_type == GateType::H) + .unwrap(); + assert_eq!( + fault_for_pauli(h_loc, &pauli_type_to_string(PauliType::X, 0)).affected_measurements, + Vec::::new(), + "SY maps X to Z, so it should not flip MZ" + ); + assert_eq!( + fault_for_pauli(h_loc, &pauli_type_to_string(PauliType::Y, 0)).affected_measurements, + vec![0], + "SY maps Y to Y, so it should flip MZ" + ); + assert_eq!( + fault_for_pauli(h_loc, &pauli_type_to_string(PauliType::Z, 0)).affected_measurements, + vec![0], + "SY maps Z to X, so it should flip MZ" + ); + + let mut face = TickCircuit::new(); + face.tick().h(&[QubitId(0)]); + face.tick().f(&[QubitId(0)]); + face.tick().mz(&[QubitId(0)]); + face.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".to_string()), + ); + face.set_meta( + "detectors", + pecos_quantum::Attribute::String("[]".to_string()), + ); + face.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let face_catalog = build_fault_catalog( + &face, + &StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + let h_loc = face_catalog + .locations + .iter() + .find(|loc| loc.gate_type == GateType::H) + .unwrap(); + assert_eq!( + fault_for_pauli(h_loc, &pauli_type_to_string(PauliType::X, 0)).affected_measurements, + vec![0], + "F maps X to Y, so it should flip MZ" + ); + assert_eq!( + fault_for_pauli(h_loc, &pauli_type_to_string(PauliType::Y, 0)).affected_measurements, + Vec::::new(), + "F maps Y to Z, so it should not flip MZ" + ); + assert_eq!( + fault_for_pauli(h_loc, &pauli_type_to_string(PauliType::Z, 0)).affected_measurements, + vec![0], + "F maps Z to X, so it should flip MZ" + ); + + let mut face_dagger = TickCircuit::new(); + face_dagger.tick().h(&[QubitId(0)]); + face_dagger.tick().fdg(&[QubitId(0)]); + face_dagger.tick().mz(&[QubitId(0)]); + face_dagger.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".to_string()), + ); + face_dagger.set_meta( + "detectors", + pecos_quantum::Attribute::String("[]".to_string()), + ); + face_dagger.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let face_dagger_catalog = build_fault_catalog( + &face_dagger, + &StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + let h_loc = face_dagger_catalog + .locations + .iter() + .find(|loc| loc.gate_type == GateType::H) + .unwrap(); + assert_eq!( + fault_for_pauli(h_loc, &pauli_type_to_string(PauliType::X, 0)).affected_measurements, + Vec::::new(), + "Fdg maps X to Z, so it should not flip MZ" + ); + assert_eq!( + fault_for_pauli(h_loc, &pauli_type_to_string(PauliType::Y, 0)).affected_measurements, + vec![0], + "Fdg maps Y to X, so it should flip MZ" + ); + assert_eq!( + fault_for_pauli(h_loc, &pauli_type_to_string(PauliType::Z, 0)).affected_measurements, + vec![0], + "Fdg maps Z to Y, so it should flip MZ" + ); + + let mut two_qubit = TickCircuit::new(); + two_qubit.tick().cx(&[(QubitId(0), QubitId(1))]); + two_qubit.tick().sxx(&[(QubitId(0), QubitId(1))]); + two_qubit.tick().mz(&[QubitId(0), QubitId(1)]); + two_qubit.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("2".to_string()), + ); + two_qubit.set_meta( + "detectors", + pecos_quantum::Attribute::String("[]".to_string()), + ); + two_qubit.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let two_catalog = build_fault_catalog( + &two_qubit, + &StochasticNoiseParams { + p1: 0.0, + p2: 0.15, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + let cx_loc = two_catalog + .locations + .iter() + .find(|loc| loc.gate_type == GateType::CX) + .unwrap(); + assert_eq!( + fault_for_pauli(cx_loc, &pauli_type_to_string(PauliType::X, 0)).affected_measurements, + vec![0], + "SXX leaves XI as XI" + ); + assert_eq!( + fault_for_pauli(cx_loc, &pauli_type_to_string(PauliType::X, 1)).affected_measurements, + vec![1], + "SXX leaves IX as IX" + ); + assert_eq!( + fault_for_pauli(cx_loc, &pauli_type_to_string(PauliType::Z, 0)).affected_measurements, + vec![0, 1], + "SXX maps ZI to YX" + ); + assert_eq!( + fault_for_pauli(cx_loc, &pauli_type_to_string(PauliType::Z, 1)).affected_measurements, + vec![0, 1], + "SXX maps IZ to XY" + ); + } + + #[test] + fn test_catalog_keeps_observables_and_tracked_ops_distinct() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.pauli_operator_labeled("z_probe", PauliString::z(0)); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String("[]".to_string()), + ); + tc.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let catalog = build_fault_catalog( + &tc, + &StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + + let h_loc = catalog + .locations + .iter() + .find(|loc| loc.gate_type == GateType::H) + .unwrap(); + let x_fault = h_loc + .faults + .iter() + .find(|fault| fault.pauli.as_ref() == Some(&PauliString::x(0))) + .unwrap(); + let y_fault = h_loc + .faults + .iter() + .find(|fault| fault.pauli.as_ref() == Some(&PauliString::y(0))) + .unwrap(); + let z_fault = h_loc + .faults + .iter() + .find(|fault| fault.pauli.as_ref() == Some(&PauliString::z(0))) + .unwrap(); + + assert_eq!(x_fault.affected_observables, Vec::::new()); + assert_eq!(x_fault.affected_tracked_ops, vec![0]); + assert_eq!(y_fault.affected_tracked_ops, vec![0]); + assert_eq!(z_fault.affected_tracked_ops, Vec::::new()); + + let configs: Vec<_> = catalog.fault_configurations(1).collect(); + assert!(configs + .iter() + .any(|config| config.affected_tracked_ops.as_slice() == [0] + && config.affected_observables.is_empty())); + } + + #[test] + fn test_catalog_meas_prep_probabilities() { + // PZ(0) MZ(0): prep X fault goes directly to MZ (flips it) + let mut tc = TickCircuit::new(); + tc.tick().pz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".to_string()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String("[]".to_string()), + ); + tc.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let noise = StochasticNoiseParams { + p1: 0.0, + p2: 0.0, + p_meas: 0.007, + p_prep: 0.003, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + + let prep = catalog + .locations + .iter() + .find(|l| l.faults.iter().any(|f| f.kind == FaultKind::PrepFlip)); + assert!(prep.is_some(), "Should have a prep fault location"); + let prep = prep.unwrap(); + assert!((prep.channel_probability - 0.003).abs() < 1e-10); + assert!(prep.faults[0].pauli.is_none()); + + let meas = catalog.locations.iter().find(|l| { + l.faults + .iter() + .any(|f| f.kind == FaultKind::MeasurementFlip) + }); + assert!(meas.is_some(), "Should have a measurement fault location"); + let meas = meas.unwrap(); + assert!((meas.channel_probability - 0.007).abs() < 1e-10); + assert!(meas.faults[0].pauli.is_none()); + } + + #[test] + fn test_catalog_separate_locations_same_detector_effect() { + // Two H gates on same qubit → two separate locations + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".to_string()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String(r#"[{"records": [-1]}]"#.to_string()), + ); + tc.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let noise = StochasticNoiseParams { + p1: 0.01, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + + // Both H gates → separate locations even if they have the same detector effect + let h_locs: Vec<_> = catalog + .locations + .iter() + .filter(|l| l.gate_type == GateType::H) + .collect(); + assert_eq!( + h_locs.len(), + 2, + "Two H gates should produce two separate locations" + ); + } + + #[test] + fn test_catalog_full_configuration_probability() { + // H(0) MZ(0) with p1=0.03, p_meas=0.01. + // Two locations: H (3 alts) and MZ (1 alt). + // Pick alt 0 at H, no fault at MZ: + // P = (0.03/3) * (1 - 0.01) = 0.01 * 0.99 = 0.0099 + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".to_string()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String("[]".to_string()), + ); + tc.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + assert_eq!(catalog.locations.len(), 2); // H + MZ + + let h_loc = &catalog.locations[0]; // H + let mz_loc = &catalog.locations[1]; // MZ + + // Pick first H alternative, no fault at MZ + let alt_prob = h_loc.faults[0].absolute_probability; // 0.03/3 = 0.01 + let no_mz_prob = mz_loc.no_fault_probability; // 1 - 0.01 = 0.99 + let config_prob = alt_prob * no_mz_prob; + + assert!((config_prob - 0.0099).abs() < 1e-10); + } + + // ---- fault_configurations iterator tests ---- + + #[test] + fn test_configurations_k0_one_no_fault_event() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".into()), + ); + tc.set_meta("detectors", pecos_quantum::Attribute::String("[]".into())); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + + let configs: Vec<_> = catalog.fault_configurations(0).collect(); + assert_eq!(configs.len(), 1); + let c = &configs[0]; + assert!(c.location_indices.is_empty()); + assert!(c.alternative_indices.is_empty()); + assert!(c.affected_measurements.is_empty()); + assert!(c.affected_detectors.is_empty()); + assert_eq!(c.selected_probability, 1.0); + // config_prob = product of all no_fault_probability + let expected: f64 = catalog + .locations + .iter() + .map(|l| l.no_fault_probability) + .product(); + assert!((c.configuration_probability - expected).abs() < 1e-12); + } + + #[test] + fn test_configurations_k1_matches_single_fault() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".into()), + ); + tc.set_meta("detectors", pecos_quantum::Attribute::String("[]".into())); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + + let configs: Vec<_> = catalog.fault_configurations(1).collect(); + // Total k=1 configs = sum of num_alternatives across all locations + let expected_count: usize = catalog.locations.iter().map(|l| l.num_alternatives).sum(); + assert_eq!(configs.len(), expected_count); + + // First config should match first location, first alternative + let c = &configs[0]; + assert_eq!(c.location_indices, vec![0]); + assert_eq!(c.alternative_indices, vec![0]); + let alt = &catalog.locations[0].faults[0]; + assert_eq!(c.affected_measurements, alt.affected_measurements); + assert!((c.selected_probability - alt.absolute_probability).abs() < 1e-12); + } + + #[test] + fn test_configurations_k2_xor_cancels_duplicate_effects() { + // Two H gates both flipping measurement 0 → XOR cancels + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".into()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String(r#"[{"records":[-1]}]"#.into()), + ); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + assert_eq!(catalog.locations.len(), 2); + + // Find a k=2 config where both locations fire with Z alternative (flips MZ) + // Z after first H → X at second H → X at MZ → flips meas 0 + // Z after second H → Z at MZ → doesn't flip + // So to get XOR cancel: need two alternatives that BOTH flip meas 0 + let configs: Vec<_> = catalog.fault_configurations(2).collect(); + // Check that some configs have empty affected_measurements (XOR cancel) + let cancelled: Vec<_> = configs + .iter() + .filter(|c| c.affected_measurements.is_empty()) + .collect(); + assert!(!cancelled.is_empty(), "Some k=2 configs should XOR-cancel"); + } + + #[test] + fn test_configurations_k2_probability_hand_calc() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".into()), + ); + tc.set_meta("detectors", pecos_quantum::Attribute::String("[]".into())); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + // 2 locations: H (3 alts, p=0.03) and MZ (1 alt, p=0.01) + + let configs: Vec<_> = catalog.fault_configurations(2).collect(); + // k=2 means both locations fire + // selected_probability = (0.03/3) * (0.01/1) = 0.01 * 0.01 = 0.0001 + // configuration_probability = selected * (no unselected) = 0.0001 + assert_eq!(configs.len(), 3); // 3 alternatives at H × 1 at MZ + for c in &configs { + assert!((c.selected_probability - 0.0001).abs() < 1e-12); + assert!((c.configuration_probability - 0.0001).abs() < 1e-12); + } + } + + #[test] + fn test_configurations_all_fault_weights_sum_to_one() { + let mut tc = TickCircuit::new(); + tc.tick().pz(&[QubitId(0)]); + tc.tick().h(&[QubitId(0)]); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(1)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("2".into()), + ); + tc.set_meta("detectors", pecos_quantum::Attribute::String("[]".into())); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let noise = StochasticNoiseParams { + p1: 0.01, + p2: 0.05, + p_meas: 0.02, + p_prep: 0.01, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + + let total: f64 = (0..=catalog.locations.len()) + .flat_map(|k| catalog.fault_configurations(k)) + .map(|c| c.configuration_probability) + .sum(); + + assert!( + (total - 1.0).abs() < 1e-12, + "all truncated-by-k configurations across k=0..N should sum to 1, got {total}" + ); + } + + #[test] + fn test_configurations_iterator_is_lazy() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".into()), + ); + tc.set_meta("detectors", pecos_quantum::Attribute::String("[]".into())); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + + // Take only first 2 items from k=1 iterator (doesn't allocate all) + let first_two: Vec<_> = catalog.fault_configurations(1).take(2).collect(); + assert_eq!(first_two.len(), 2); + } + + // ---- RawMeasurementPlan tests ---- + + #[test] + fn test_plan_bell_r_source_shared_by_copy() { + // Bell: H(0) CX(0,1) MZ(0) MZ(1) + // m0 = Random, m1 = Copy(m0). Both share the same r-source. + // With zero noise, m0 == m1 for all shots. + use pecos_simulators::SymbolicSparseStab; + + let mut sim = SymbolicSparseStab::new(2); + sim.h(&[0]).cx(&[(0, 1)]); + sim.mz(&[0]); + sim.mz(&[1]); + + let plan = RawMeasurementPlan::new(sim.measurement_history(), vec![]); + let result = plan.sample(1000, 42); + + for shot in 0..1000 { + let m0 = result.get(shot, 0).0; + let m1 = result.get(shot, 1).0; + assert_eq!(m0, m1, "Bell pair: m0 must equal m1 (shot {shot})"); + } + } + + #[test] + fn test_plan_physical_fault_does_not_inherit_copy() { + // Bell: m0 = Random, m1 = Copy(m0). + // Add a physical fault that flips ONLY m0 with p=1. + // Result: m0 is flipped, m1 is NOT — the fault does not propagate + // through the ideal Copy dependency. + use pecos_simulators::SymbolicSparseStab; + + let mut sim = SymbolicSparseStab::new(2); + sim.h(&[0]).cx(&[(0, 1)]); + sim.mz(&[0]); + sim.mz(&[1]); + + // Fault that always fires, flipping only m0 + let mechanisms = vec![FaultMechanism { + probability: 1.0, + alternatives: vec![vec![0]], + }]; + let plan = RawMeasurementPlan::new(sim.measurement_history(), mechanisms); + let result = plan.sample(1000, 42); + + for shot in 0..1000 { + let m0 = result.get(shot, 0).0; + let m1 = result.get(shot, 1).0; + // m0 = base XOR 1 (always flipped), m1 = base (not flipped) + // Since base m0 == base m1, after flip: m0 != m1 + assert_ne!(m0, m1, "Fault on m0 must not inherit to m1 (shot {shot})"); + } + } + + #[test] + fn test_plan_grouped_alternatives_preserve_empty() { + // Deterministic base (m0 = Fixed(false) = always 0) with a p=1 mechanism + // having 3 alternatives: [flip m0, flip m0, no-op]. + // Each shot fires and picks one uniformly → 2/3 get flipped. + use pecos_simulators::SymbolicSparseStab; + + let mut sim = SymbolicSparseStab::new(1); + sim.mz(&[0]); // m0 = Fixed(false) + + let mechanisms = vec![FaultMechanism { + probability: 1.0, + alternatives: vec![vec![0], vec![0], vec![]], + }]; + let plan = RawMeasurementPlan::new(sim.measurement_history(), mechanisms); + let result = plan.sample(9000, 42); + + // base=0, fault flips with prob 2/3 → mean should be ~2/3. + let ones: usize = (0..9000).filter(|&s| result.get(s, 0).0).count(); + let mean = ones as f64 / 9000.0; + assert!( + (mean - 2.0 / 3.0).abs() < 0.03, + "Expected ~2/3 flip rate from grouped alternatives, got {mean:.4}" + ); + } + + #[test] + fn test_plan_geometric_sampling_firing_rates() { + use pecos_simulators::SymbolicSparseStab; + + let mut sim = SymbolicSparseStab::new(1); + sim.mz(&[0]); // deterministic base measurement: m0 = 0 + + let shots = 200_000usize; + for (p, low, high) in [ + (0.001, 120, 280), + (0.05, 9400, 10600), + (0.5, 99_000, 101_000), + ] { + let mechanisms = vec![FaultMechanism { + probability: p, + alternatives: vec![vec![0]], + }]; + let plan = RawMeasurementPlan::new(sim.measurement_history(), mechanisms); + let result = plan.sample(shots, 42); + + let firing_count = (0..shots).filter(|&shot| result.get(shot, 0).0).count(); + assert!( + (low..=high).contains(&firing_count), + "p={p} firing count {firing_count} outside expected range [{low}, {high}]" + ); + } + } + + #[test] + fn test_sample_raw_word_boundaries_are_masked() { + use pecos_simulators::SymbolicSparseStab; + + let mut sim = SymbolicSparseStab::new(1); + sim.mz(&[0]); // deterministic base measurement: m0 = 0 + + let mechanisms = vec![FaultMechanism { + probability: 1.0, + alternatives: vec![vec![0]], + }]; + let plan = RawMeasurementPlan::new(sim.measurement_history(), mechanisms); + + for shots in [63usize, 64, 65, 128, 129] { + let raw = plan.sample_raw(shots, 42); + let expected_words = shots.div_ceil(64); + assert_eq!(raw.columns[0].len(), expected_words); + for shot in 0..shots { + let word_idx = shot / 64; + let bit_idx = shot % 64; + assert_ne!( + raw.columns[0][word_idx] & (1u64 << bit_idx), + 0, + "shot {shot} should be flipped for p=1" + ); + } + + let remainder = shots % 64; + if remainder != 0 { + let tail_mask = !((1u64 << remainder) - 1); + assert_eq!( + raw.columns[0].last().copied().unwrap() & tail_mask, + 0, + "bits beyond {shots} shots should be masked off" + ); + } + } + } + + #[test] + fn test_sample_raw_masks_final_word_no_mechanisms() { + // 100 shots (not a multiple of 64): final word should have bits 100..128 = 0 + use pecos_simulators::SymbolicSparseStab; + + let mut sim = SymbolicSparseStab::new(1); + sim.h(&[0]); + sim.mz(&[0]); // Random + + let plan = RawMeasurementPlan::new(sim.measurement_history(), vec![]); + let raw = plan.sample_raw(100, 42); + + // 100 shots → 2 words. Last word should have bits 36..63 = 0 (100 - 64 = 36 valid bits) + assert_eq!(raw.columns[0].len(), 2); + let last_word = raw.columns[0][1]; + let valid_bits = 100 - 64; + let tail_mask = !((1u64 << valid_bits) - 1); + assert_eq!( + last_word & tail_mask, + 0, + "Bits beyond shots should be zero in measurement columns" + ); + } + + #[test] + fn test_sample_raw_r_columns_masked() { + use pecos_simulators::SymbolicSparseStab; + + let mut sim = SymbolicSparseStab::new(1); + sim.h(&[0]); + sim.mz(&[0]); // Random + + let plan = RawMeasurementPlan::new(sim.measurement_history(), vec![]); + let raw = plan.sample_raw(100, 42); + + assert_eq!(raw.r_columns.len(), 1); + assert_eq!(raw.r_columns[0].len(), 2); + let last_word = raw.r_columns[0][1]; + let valid_bits = 100 - 64; + let tail_mask = !((1u64 << valid_bits) - 1); + assert_eq!( + last_word & tail_mask, + 0, + "Bits beyond shots should be zero in r_columns" + ); + } + + #[test] + fn test_sample_raw_bell_r_source_mapping() { + // Bell: H(0) CX(0,1) MZ(0) MZ(1) + // m0=Random, m1=Copy(m0) → exactly one r-source at measurement 0 + use pecos_simulators::SymbolicSparseStab; + + let mut sim = SymbolicSparseStab::new(2); + sim.h(&[0]).cx(&[(0, 1)]); + sim.mz(&[0]); + sim.mz(&[1]); + + let plan = RawMeasurementPlan::new(sim.measurement_history(), vec![]); + let raw = plan.sample_raw(64, 42); + + assert_eq!(raw.r_columns.len(), 1, "Bell pair has one r-source"); + assert_eq!( + raw.r_source_measurements, + vec![0], + "r-source introduced at measurement 0" + ); + // The r column should equal the m0 column (since m0 = Random = r0 directly) + assert_eq!(raw.r_columns[0], raw.columns[0]); + // And m1 = Copy(m0), so columns[1] == columns[0] + assert_eq!(raw.columns[0], raw.columns[1]); + } + + #[test] + fn test_sample_raw_zero_shots_invariant() { + // Bell circuit with zero shots: r_columns length must match r_source_measurements + use pecos_simulators::SymbolicSparseStab; + + let mut sim = SymbolicSparseStab::new(2); + sim.h(&[0]).cx(&[(0, 1)]); + sim.mz(&[0]); + sim.mz(&[1]); + + let plan = RawMeasurementPlan::new(sim.measurement_history(), vec![]); + let raw = plan.sample_raw(0, 42); + + assert_eq!(raw.columns.len(), 2); + assert!(raw.columns[0].is_empty()); + assert!(raw.columns[1].is_empty()); + assert_eq!(raw.r_source_measurements, vec![0]); + assert_eq!(raw.r_columns.len(), 1); + assert!(raw.r_columns[0].is_empty()); + assert_eq!(raw.shots, 0); + } +} diff --git a/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs b/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs index a6ec9c3c1..5e61ec6e7 100644 --- a/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs +++ b/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs @@ -970,21 +970,59 @@ impl<'a> GadgetChecker<'a> { pecos_core::gate_type::GateType::H => { prop.h(&qubits); } + pecos_core::gate_type::GateType::F => { + prop.f(&qubits); + } + pecos_core::gate_type::GateType::Fdg => { + prop.fdg(&qubits); + } + pecos_core::gate_type::GateType::SX => { + prop.sx(&qubits); + } + pecos_core::gate_type::GateType::SXdg => { + prop.sxdg(&qubits); + } + pecos_core::gate_type::GateType::SY => { + prop.sy(&qubits); + } + pecos_core::gate_type::GateType::SYdg => { + prop.sydg(&qubits); + } pecos_core::gate_type::GateType::SZ => { prop.sz(&qubits); } pecos_core::gate_type::GateType::SZdg => { prop.szdg(&qubits); } - pecos_core::gate_type::GateType::CX => { - if qubits.len() >= 2 { - prop.cx(&[(qubits[0], qubits[1])]); - } + pecos_core::gate_type::GateType::CX if qubits.len() >= 2 => { + prop.cx(&[(qubits[0], qubits[1])]); } - pecos_core::gate_type::GateType::CZ => { - if qubits.len() >= 2 { - prop.cz(&[(qubits[0], qubits[1])]); - } + pecos_core::gate_type::GateType::CY if qubits.len() >= 2 => { + prop.cy(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::CZ if qubits.len() >= 2 => { + prop.cz(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SXX if qubits.len() >= 2 => { + prop.sxx(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SXXdg if qubits.len() >= 2 => { + prop.sxxdg(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SYY if qubits.len() >= 2 => { + prop.syy(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SYYdg if qubits.len() >= 2 => { + prop.syydg(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SZZ if qubits.len() >= 2 => { + prop.szz(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SZZdg if qubits.len() >= 2 => { + prop.szzdg(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SWAP if qubits.len() >= 2 => { + prop.swap(&[(qubits[0], qubits[1])]); } pecos_core::gate_type::GateType::X => { prop.x(&qubits); @@ -1709,21 +1747,59 @@ impl<'a> GadgetChecker<'a> { pecos_core::gate_type::GateType::H => { prop.h(&qubits); } + pecos_core::gate_type::GateType::F => { + prop.f(&qubits); + } + pecos_core::gate_type::GateType::Fdg => { + prop.fdg(&qubits); + } + pecos_core::gate_type::GateType::SX => { + prop.sx(&qubits); + } + pecos_core::gate_type::GateType::SXdg => { + prop.sxdg(&qubits); + } + pecos_core::gate_type::GateType::SY => { + prop.sy(&qubits); + } + pecos_core::gate_type::GateType::SYdg => { + prop.sydg(&qubits); + } pecos_core::gate_type::GateType::SZ => { prop.sz(&qubits); } pecos_core::gate_type::GateType::SZdg => { prop.szdg(&qubits); } - pecos_core::gate_type::GateType::CX => { - if qubits.len() >= 2 { - prop.cx(&[(qubits[0], qubits[1])]); - } + pecos_core::gate_type::GateType::CX if qubits.len() >= 2 => { + prop.cx(&[(qubits[0], qubits[1])]); } - pecos_core::gate_type::GateType::CZ => { - if qubits.len() >= 2 { - prop.cz(&[(qubits[0], qubits[1])]); - } + pecos_core::gate_type::GateType::CY if qubits.len() >= 2 => { + prop.cy(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::CZ if qubits.len() >= 2 => { + prop.cz(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SXX if qubits.len() >= 2 => { + prop.sxx(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SXXdg if qubits.len() >= 2 => { + prop.sxxdg(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SYY if qubits.len() >= 2 => { + prop.syy(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SYYdg if qubits.len() >= 2 => { + prop.syydg(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SZZ if qubits.len() >= 2 => { + prop.szz(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SZZdg if qubits.len() >= 2 => { + prop.szzdg(&[(qubits[0], qubits[1])]); + } + pecos_core::gate_type::GateType::SWAP if qubits.len() >= 2 => { + prop.swap(&[(qubits[0], qubits[1])]); } pecos_core::gate_type::GateType::X => { prop.x(&qubits); diff --git a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs index 4774ef4b0..7748f5b1e 100644 --- a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs @@ -10,7 +10,7 @@ //! //! ``` //! use pecos_qec::fault_tolerance::InfluenceBuilder; -//! use pecos_qec::fault_tolerance::noisy_sampler::{NoisySampler, UniformNoiseModel}; +//! use pecos_qec::fault_tolerance::dem_builder::DemSampler; //! use pecos_quantum::DagCircuit; //! //! // Build a syndrome extraction circuit @@ -24,13 +24,13 @@ //! let builder = InfluenceBuilder::new(&dag); //! let influence_map = builder.build(); //! -//! // Use with CPU sampler -//! let noise = UniformNoiseModel::depolarizing(0.001); -//! let mut sampler = NoisySampler::new(&influence_map, noise, 42); -//! let results = sampler.sample(100); +//! // Build a fast DemSampler from the influence map +//! let num_locations = influence_map.locations.len(); +//! let sampler = DemSampler::from_influence_map(&influence_map, &vec![0.001; num_locations]); +//! let stats = sampler.sample_statistics(100, 42); //! ``` -use super::propagator::dag::{DagFaultInfluenceMap, DagSpacetimeLocation}; +use super::propagator::dag::{DagFaultInfluenceMap, DagSpacetimeLocation, DemOutputMetadata}; use super::propagator::types::{DetectorId, MeasurementId}; use super::propagator::{DagFaultAnalyzer, DagPropagator, Direction, Pauli, apply_gate}; use pecos_core::QubitId; @@ -42,11 +42,26 @@ use std::collections::BinaryHeap; /// /// This integrates forward symbolic simulation with backward propagation /// to create complete influence maps suitable for noisy sampling. +/// Re-export `PauliString` as the type used for Pauli operator tracking. +/// +/// All circuit annotations (detectors, observables, operators) are Pauli +/// strings tracked for flipping via backward propagation. The difference +/// is role and readout: +/// +/// | Kind | Pauli | Readout | API | +/// |------|-------|---------|-----| +/// | Detector | Z on measured qubits | measurement XOR = 0 | `dag.detector(&[...])` | +/// | Observable | Z on measured qubits | measurement XOR | `dag.observable(&[...])` | +/// | Operator | user-specified | propagation only | `dag.pauli_operator(&[...])` | +pub use pecos_core::PauliString; + pub struct InfluenceBuilder<'a> { dag: &'a pecos_quantum::DagCircuit, - /// Logical operators to track (qubit indices with X or Z component) - logical_x_qubits: Vec, - logical_z_qubits: Vec, + /// Pauli operators to track for flipping, with optional start position. + /// `None` means propagate from circuit end; `Some(node)` means propagate + /// from that DAG node's topological position. + /// (`metadata`, meta-gate node) + pauli_operators: Vec<(DemOutputMetadata, Option)>, } impl<'a> InfluenceBuilder<'a> { @@ -55,26 +70,96 @@ impl<'a> InfluenceBuilder<'a> { pub fn new(dag: &'a pecos_quantum::DagCircuit) -> Self { Self { dag, - logical_x_qubits: Vec::new(), - logical_z_qubits: Vec::new(), + pauli_operators: Vec::new(), } } - /// Add a logical X operator to track. + /// Add a tracked X operator (X on all specified qubits). + #[must_use] + pub fn with_x(mut self, qubits: &[usize]) -> Self { + self.pauli_operators.push(( + DemOutputMetadata::tracked_operator(PauliString::xs(qubits)), + None, + )); + self + } + + /// Add a tracked Z operator (Z on all specified qubits). + #[must_use] + pub fn with_z(mut self, qubits: &[usize]) -> Self { + self.pauli_operators.push(( + DemOutputMetadata::tracked_operator(PauliString::zs(qubits)), + None, + )); + self + } + + /// Add a tracked Y operator (Y on all specified qubits). + #[must_use] + pub fn with_y(mut self, qubits: &[usize]) -> Self { + self.pauli_operators.push(( + DemOutputMetadata::tracked_operator(PauliString::ys(qubits)), + None, + )); + self + } + + /// Add a Pauli check: track whether this Pauli string flips due to faults. + /// + /// Unlike observables (`dag.observable()`), a Pauli check + /// uses backward propagation to detect flips WITHOUT requiring a measurement. + /// + /// # Example /// - /// The logical X is defined as X on all specified qubits. + /// ```ignore + /// // Check if Y = X_0 * Z_1 * Z_2 flips + /// builder.with_pauli_operator(PauliString::from_paulis(vec![(0, 1), (1, 3), (2, 3)])) + /// ``` #[must_use] - pub fn with_logical_x(mut self, qubits: Vec) -> Self { - self.logical_x_qubits = qubits; + pub fn with_pauli_operator(mut self, pauli: PauliString) -> Self { + self.pauli_operators + .push((DemOutputMetadata::tracked_operator(pauli), None)); self } - /// Add a logical Z operator to track. + /// Extract tracked operator annotations from the circuit. /// - /// The logical Z is defined as Z on all specified qubits. + /// Operator annotations have a corresponding `PauliOperatorMeta` node + /// that marks their time position. Observable annotations are + /// measurement-record outputs and are handled by DEM/sampler builders, + /// not by backward tracked-operator propagation. + /// + /// Detector annotations are NOT handled here -- they are processed + /// by `DemSamplerBuilder::with_circuit_annotations` which maps them + /// to auto-detected detectors. #[must_use] - pub fn with_logical_z(mut self, qubits: Vec) -> Self { - self.logical_z_qubits = qubits; + pub fn with_circuit_annotations(mut self, circuit: &pecos_quantum::DagCircuit) -> Self { + // Find PauliOperatorMeta nodes in topological order. + // The nth meta-gate corresponds to the nth Operator annotation. + let meta_nodes: Vec = circuit + .topological_order() + .into_iter() + .filter(|&node| circuit.gate(node).is_some_and(|g| g.gate_type.is_meta())) + .collect(); + + let mut operator_idx = 0; + for ann in circuit.annotations() { + match &ann.kind { + pecos_quantum::AnnotationKind::Operator => { + let meta_node = meta_nodes.get(operator_idx).copied(); + operator_idx += 1; + self.pauli_operators.push(( + DemOutputMetadata::tracked_operator(ann.pauli.clone()) + .with_optional_label(ann.label.clone()), + meta_node, + )); + } + pecos_quantum::AnnotationKind::Observable { .. } => {} + pecos_quantum::AnnotationKind::Detector { .. } => { + // Detectors handled separately by DemSamplerBuilder + } + } + } self } @@ -83,7 +168,7 @@ impl<'a> InfluenceBuilder<'a> { /// This performs: /// 1. Forward symbolic simulation to get measurement correlations /// 2. Detector extraction from deterministic measurements - /// 3. Backward propagation from detectors and logicals + /// 3. Backward propagation from detectors and DEM outputs #[must_use] pub fn build(&self) -> DagFaultInfluenceMap { // Step 1: Run forward symbolic simulation @@ -125,14 +210,31 @@ impl<'a> InfluenceBuilder<'a> { pecos_quantum::GateType::H => { sim.h(&[qubits[0]]); } + pecos_quantum::GateType::F => { + sim.sx(&[qubits[0]]); + sim.sz(&[qubits[0]]); + } + pecos_quantum::GateType::Fdg => { + sim.szdg(&[qubits[0]]); + sim.sxdg(&[qubits[0]]); + } + pecos_quantum::GateType::SX => { + sim.sx(&[qubits[0]]); + } + pecos_quantum::GateType::SXdg => { + sim.sxdg(&[qubits[0]]); + } + pecos_quantum::GateType::SY => { + sim.sy(&[qubits[0]]); + } + pecos_quantum::GateType::SYdg => { + sim.sydg(&[qubits[0]]); + } pecos_quantum::GateType::SZ => { sim.sz(&[qubits[0]]); } pecos_quantum::GateType::SZdg => { - // SZdg = SZ^3 = SZ * SZ * SZ - sim.sz(&[qubits[0]]); - sim.sz(&[qubits[0]]); - sim.sz(&[qubits[0]]); + sim.szdg(&[qubits[0]]); } pecos_quantum::GateType::X => { sim.x(&[qubits[0]]); @@ -146,11 +248,32 @@ impl<'a> InfluenceBuilder<'a> { pecos_quantum::GateType::CX => { sim.cx(&[(qubits[0], qubits[1])]); } + pecos_quantum::GateType::CY => { + sim.cy(&[(qubits[0], qubits[1])]); + } pecos_quantum::GateType::CZ => { - // CZ = H(target) CX H(target) - sim.h(&[qubits[1]]); - sim.cx(&[(qubits[0], qubits[1])]); - sim.h(&[qubits[1]]); + sim.cz(&[(qubits[0], qubits[1])]); + } + pecos_quantum::GateType::SXX => { + sim.sxx(&[(qubits[0], qubits[1])]); + } + pecos_quantum::GateType::SXXdg => { + sim.sxxdg(&[(qubits[0], qubits[1])]); + } + pecos_quantum::GateType::SYY => { + sim.syy(&[(qubits[0], qubits[1])]); + } + pecos_quantum::GateType::SYYdg => { + sim.syydg(&[(qubits[0], qubits[1])]); + } + pecos_quantum::GateType::SZZ => { + sim.szz(&[(qubits[0], qubits[1])]); + } + pecos_quantum::GateType::SZZdg => { + sim.szzdg(&[(qubits[0], qubits[1])]); + } + pecos_quantum::GateType::SWAP => { + sim.swap(&[(qubits[0], qubits[1])]); } pecos_quantum::GateType::MZ | pecos_quantum::GateType::MeasureFree => { sim.mz(&[qubits[0]]); @@ -222,8 +345,9 @@ impl<'a> InfluenceBuilder<'a> { map.locations = Self::extract_locations(propagator); // Build measurement node lookup - let measurements = Self::extract_measurements(propagator); + let (measurements, meas_ids) = Self::extract_measurements(propagator); map.measurements.clone_from(&measurements); + map.meas_ids = meas_ids; // Create DetectorId entries for each detector for detector in detectors { @@ -256,31 +380,35 @@ impl<'a> InfluenceBuilder<'a> { }); } - // Add logical operators as additional "detectors" for tracking + // Add tracked Pauli operators in their PECOS tracked-op namespace. let num_detectors = detectors.len(); - let mut num_logicals = 0; - - // Track logical X (sensitive to Z errors) - if !self.logical_x_qubits.is_empty() { - num_logicals += 1; - } - // Track logical Z (sensitive to X errors) - if !self.logical_z_qubits.is_empty() { - num_logicals += 1; - } + let num_tracked_ops = self.pauli_operators.len(); // Build the influence structure using backward propagation - let mut recorder = CompoundRecorder::new(map.locations.len(), num_detectors, num_logicals); + let mut recorder = + CompoundRecorder::new(map.locations.len(), num_detectors, num_tracked_ops); // Propagate from each detector Self::propagate_detectors(propagator, info, detectors, &mut recorder); - // Propagate from logicals - self.propagate_logicals(propagator, &mut recorder); + // Propagate from tracked Pauli operators. + self.propagate_tracked_ops(propagator, &mut recorder); // Convert to SoA format map.influences = recorder.into_soa(); + // Store DEM-output labels + map.dem_output_labels = self + .pauli_operators + .iter() + .map(|(metadata, _)| metadata.label.clone()) + .collect(); + map.dem_output_metadata = self + .pauli_operators + .iter() + .map(|(metadata, _)| metadata.clone()) + .collect(); + map } @@ -290,43 +418,32 @@ impl<'a> InfluenceBuilder<'a> { for &node in propagator.topo_order() { if let Some(gate) = propagator.gate(node) { + // Meta-gates are not physical -- they don't generate faults + if gate.gate_type.is_meta() { + continue; + } + let qubits: Vec = gate.qubits.to_vec(); let is_measurement = matches!( gate.gate_type, pecos_quantum::GateType::MZ | pecos_quantum::GateType::MeasureFree ); - let is_prep = matches!( - gate.gate_type, - pecos_quantum::GateType::PZ | pecos_quantum::GateType::QAlloc - ); - if is_measurement { - locations.push(DagSpacetimeLocation { - node, - qubits: qubits.clone(), - before: true, - gate_type: gate.gate_type, - }); - } else if is_prep { - locations.push(DagSpacetimeLocation { - node, - qubits: qubits.clone(), - before: false, - gate_type: gate.gate_type, - }); - } else { - locations.push(DagSpacetimeLocation { - node, - qubits: qubits.clone(), - before: true, - gate_type: gate.gate_type, - }); + // Standard circuit noise model: one fault location per gate. + // Measurement: before. All others: after. + let before = is_measurement; + for &q in &qubits { + // idle_duration() returns a non-negative integer stored as f64; + // truncation and sign loss are not a concern. + #[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)] + let idle_duration = gate.idle_duration() as u64; locations.push(DagSpacetimeLocation { node, - qubits, - before: false, + qubits: vec![q], + before, gate_type: gate.gate_type, + idle_duration, }); } } @@ -336,8 +453,10 @@ impl<'a> InfluenceBuilder<'a> { } /// Extract measurements from the propagator. - fn extract_measurements(propagator: &DagPropagator<'_>) -> Vec<(usize, usize, u8)> { - let mut measurements = Vec::new(); + fn extract_measurements( + propagator: &DagPropagator<'_>, + ) -> (Vec<(usize, usize, u8)>, Vec) { + let mut entries: Vec<(usize, usize, usize, u8, Option)> = Vec::new(); for &node in propagator.topo_order() { if let Some(gate) = propagator.gate(node) { @@ -346,13 +465,39 @@ impl<'a> InfluenceBuilder<'a> { _ => continue, }; - for qubit in &gate.qubits { - measurements.push((node, qubit.index(), basis)); + if !gate.meas_ids.is_empty() { + for (i, qubit) in gate.qubits.iter().enumerate() { + let mr = gate.meas_ids.get(i).copied(); + let sort_key = mr.map(|m| m.index()).unwrap_or(usize::MAX); + entries.push((sort_key, node, qubit.index(), basis, mr)); + } + } else { + let topo_pos = propagator.topo_position(node); + for qubit in &gate.qubits { + entries.push((topo_pos, node, qubit.index(), basis, None)); + } } } } - measurements + entries.sort_by_key(|&(sort_key, _, qubit, _, _)| (sort_key, qubit)); + + let has_meas_ids = entries.iter().any(|(_, _, _, _, mr)| mr.is_some()); + let meas_ids = if has_meas_ids { + entries + .iter() + .map(|(_, _, _, _, mr)| mr.unwrap_or(pecos_core::MeasId(usize::MAX))) + .collect() + } else { + Vec::new() + }; + + let measurements = entries + .into_iter() + .map(|(_, node, qubit, basis, _)| (node, qubit, basis)) + .collect(); + + (measurements, meas_ids) } /// Propagate backward from all detectors. @@ -398,61 +543,66 @@ impl<'a> InfluenceBuilder<'a> { &mut visited, &mut active_qubits, &mut heap, + None, // detectors: walk from circuit end ); } } - /// Propagate backward from logical operators. - fn propagate_logicals(&self, propagator: &DagPropagator<'_>, recorder: &mut CompoundRecorder) { + /// Propagate backward from tracked Pauli operators. + /// + /// If a Pauli operator has a corresponding `PauliOperatorMeta` node in the + /// DAG, propagation starts from that node's topological position. Otherwise + /// (e.g. operators added via `with_z`/`with_x` without a circuit annotation), + /// propagation walks from the circuit end. + fn propagate_tracked_ops( + &self, + propagator: &DagPropagator<'_>, + recorder: &mut CompoundRecorder, + ) { let max_node = propagator.max_node(); let max_qubit = propagator.max_qubit(); let mut visited = vec![false; max_node + 1]; let mut active_qubits = vec![false; max_qubit + 1]; let mut heap = BinaryHeap::new(); - let mut logical_idx = 0; - // Logical X (product of X on specified qubits) - sensitive to Z errors - if !self.logical_x_qubits.is_empty() { + for (dem_output_idx, (metadata, meta_node)) in self.pauli_operators.iter().enumerate() { let mut prop = PauliProp::new(); - for &q in &self.logical_x_qubits { - prop.track_x(&[q]); - } - Self::propagate_observable( - propagator, - &prop, - logical_idx, - false, // is_detector (this is a logical) - recorder, - &mut visited, - &mut active_qubits, - &mut heap, - ); - logical_idx += 1; - } - - // Logical Z (product of Z on specified qubits) - sensitive to X errors - if !self.logical_z_qubits.is_empty() { - let mut prop = PauliProp::new(); - for &q in &self.logical_z_qubits { - prop.track_z(&[q]); + for &(pauli, qubit) in metadata.pauli.paulis() { + use pecos_core::Pauli; + let q = qubit.index(); + match pauli { + Pauli::X => prop.track_x(&[q]), + Pauli::Y => prop.track_y(&[q]), + Pauli::Z => prop.track_z(&[q]), + Pauli::I => {} + } } + // Resolve the meta-gate node to its topological position. + // None means no positional bound (walk from circuit end). + let start_pos = meta_node.map(|node| propagator.topo_position(node)); + Self::propagate_observable( propagator, &prop, - logical_idx, - false, // is_detector (this is a logical) + dem_output_idx, + false, // is_detector = false (this is a DEM output) recorder, &mut visited, &mut active_qubits, &mut heap, + start_pos, ); } } /// Propagate a single observable backward and record influences. + /// + /// When `start_topo_pos` is `Some(pos)`, only gates at or before that + /// topological position are considered. This makes Pauli operator + /// annotations positional: only faults before the meta-gate affect it. #[allow(clippy::too_many_arguments)] fn propagate_observable( propagator: &DagPropagator<'_>, @@ -463,6 +613,7 @@ impl<'a> InfluenceBuilder<'a> { visited: &mut [bool], active_qubits: &mut [bool], heap: &mut BinaryHeap<(usize, usize)>, + start_topo_pos: Option, ) { // Clear work arrays visited.fill(false); @@ -476,8 +627,11 @@ impl<'a> InfluenceBuilder<'a> { if prop.contains_x(q) || prop.contains_z(q) { *is_active = true; - // Add all gates on this qubit to the heap + // Add gates on this qubit to the heap, bounded by start position for (topo_pos, node) in propagator.qubit_gates_backward(q) { + if start_topo_pos.is_some_and(|max| topo_pos > max) { + continue; + } if !visited[node] { visited[node] = true; heap.push((topo_pos, node)); @@ -492,9 +646,9 @@ impl<'a> InfluenceBuilder<'a> { // Process gates in reverse topological order while let Some((_, node)) = heap.pop() { if let Some(gate) = propagator.gate(node) { - // Record influences at before=false location - if let Some(&loc_idx) = loc_map.get(&(node, false)) { - Self::record_influence(&prop, loc_idx, target_idx, is_detector, recorder); + // Record per-qubit influences at before=false location + if let Some(qubit_locs) = loc_map.get(&(node, false)) { + Self::record_influence(&prop, qubit_locs, target_idx, is_detector, recorder); } // Track which qubits were active before the gate @@ -505,12 +659,36 @@ impl<'a> InfluenceBuilder<'a> { } } + // Prep gates (PZ/QAlloc) reset the qubit -- kill the Pauli + // and mark the qubit inactive. Faults before the prep + // cannot propagate past it. + let is_prep = matches!( + gate.gate_type, + pecos_quantum::GateType::PZ | pecos_quantum::GateType::QAlloc + ); + if is_prep { + for q in &gate.qubits { + let qi = q.index(); + // Toggle off X and Z components (XOR to zero) + if prop.contains_x(qi) { + prop.track_x(&[qi]); + } + if prop.contains_z(qi) { + prop.track_z(&[qi]); + } + if qi < active_qubits.len() { + active_qubits[qi] = false; + } + } + continue; // don't propagate further on these qubits + } + // Apply gate backward apply_gate(&mut prop, gate, Direction::Backward); - // Record influences at before=true location - if let Some(&loc_idx) = loc_map.get(&(node, true)) { - Self::record_influence(&prop, loc_idx, target_idx, is_detector, recorder); + // Record per-qubit influences at before=true location + if let Some(qubit_locs) = loc_map.get(&(node, true)) { + Self::record_influence(&prop, qubit_locs, target_idx, is_detector, recorder); } // Check if Pauli spread to new qubits @@ -537,34 +715,30 @@ impl<'a> InfluenceBuilder<'a> { } } - /// Build a map from (node, before) to location index. + /// Build a map from (node, before) to per-qubit location indices. fn build_location_map( propagator: &DagPropagator<'_>, - ) -> std::collections::HashMap<(usize, bool), usize> { - let mut map = std::collections::HashMap::new(); + ) -> std::collections::HashMap<(usize, bool), Vec<(usize, usize)>> { + // (node, before) -> [(qubit_index, loc_idx), ...] + let mut map: std::collections::HashMap<(usize, bool), Vec<(usize, usize)>> = + std::collections::HashMap::new(); let mut loc_idx = 0; for &node in propagator.topo_order() { if let Some(gate) = propagator.gate(node) { + if gate.gate_type.is_meta() { + continue; + } + let is_measurement = matches!( gate.gate_type, pecos_quantum::GateType::MZ | pecos_quantum::GateType::MeasureFree ); - let is_prep = matches!( - gate.gate_type, - pecos_quantum::GateType::PZ | pecos_quantum::GateType::QAlloc - ); - if is_measurement { - map.insert((node, true), loc_idx); - loc_idx += 1; - } else if is_prep { - map.insert((node, false), loc_idx); - loc_idx += 1; - } else { - map.insert((node, true), loc_idx); - loc_idx += 1; - map.insert((node, false), loc_idx); + let before = is_measurement; + for q in &gate.qubits { + let qi = q.index(); + map.entry((node, before)).or_default().push((qi, loc_idx)); loc_idx += 1; } } @@ -573,50 +747,41 @@ impl<'a> InfluenceBuilder<'a> { map } - /// Record influence of a fault at a location on a target (detector or logical). + /// Record per-qubit influence of a fault at a gate location. fn record_influence( prop: &PauliProp, - loc_idx: usize, + qubit_locs: &[(usize, usize)], // [(qubit, loc_idx), ...] target_idx: usize, is_detector: bool, recorder: &mut CompoundRecorder, ) { - // Check each Pauli type - for pauli in [Pauli::X, Pauli::Y, Pauli::Z] { - if Self::fault_anticommutes(prop, pauli) { - if is_detector { - #[allow(clippy::cast_possible_truncation)] // index fits in u32 - recorder.record_detector(loc_idx, pauli, target_idx as u32); - } else { - #[allow(clippy::cast_possible_truncation)] // index fits in u32 - recorder.record_logical(loc_idx, pauli, target_idx as u32); + for &(qubit, loc_idx) in qubit_locs { + for pauli in [Pauli::X, Pauli::Y, Pauli::Z] { + if Self::fault_anticommutes_qubit(prop, qubit, pauli) { + if is_detector { + #[allow(clippy::cast_possible_truncation)] + recorder.record_detector(loc_idx, pauli, target_idx as u32); + } else { + #[allow(clippy::cast_possible_truncation)] + recorder.record_dem_output(loc_idx, pauli, target_idx as u32); + } } } } } - /// Check if a fault Pauli anticommutes with the propagated observable. - fn fault_anticommutes(prop: &PauliProp, fault: Pauli) -> bool { - let mut anticom_count = 0; + /// Check if a single-qubit fault Pauli anticommutes with the propagated + /// observable on a specific qubit. + fn fault_anticommutes_qubit(prop: &PauliProp, qubit: usize, fault: Pauli) -> bool { + let has_x = prop.contains_x(qubit); + let has_z = prop.contains_z(qubit); match fault { - Pauli::I => return false, - Pauli::X => { - // X fault anticommutes with Z component - anticom_count += prop.get_z_qubits().len(); - } - Pauli::Z => { - // Z fault anticommutes with X component - anticom_count += prop.get_x_qubits().len(); - } - Pauli::Y => { - // Y fault anticommutes with both X and Z - anticom_count += prop.get_x_qubits().len(); - anticom_count += prop.get_z_qubits().len(); - } + Pauli::I => false, + Pauli::X => has_z, // X anticommutes with Z + Pauli::Z => has_x, // Z anticommutes with X + Pauli::Y => has_x ^ has_z, // Y anticommutes with X or Z but not both } - - anticom_count % 2 == 1 } } @@ -643,31 +808,31 @@ struct CompoundRecorder { #[allow(dead_code)] num_detectors: usize, #[allow(dead_code)] - num_logicals: usize, + num_tracked_ops: usize, // Buckets for detector influences [loc_idx][pauli] -> Vec detector_x: Vec>, detector_y: Vec>, detector_z: Vec>, - // Buckets for logical influences - logical_x: Vec>, - logical_y: Vec>, - logical_z: Vec>, + // Buckets for DEM-output influences. + dem_output_x: Vec>, + dem_output_y: Vec>, + dem_output_z: Vec>, } impl CompoundRecorder { - fn new(num_locations: usize, num_detectors: usize, num_logicals: usize) -> Self { + fn new(num_locations: usize, num_detectors: usize, num_tracked_ops: usize) -> Self { Self { num_locations, num_detectors, - num_logicals, + num_tracked_ops, detector_x: vec![Vec::new(); num_locations], detector_y: vec![Vec::new(); num_locations], detector_z: vec![Vec::new(); num_locations], - logical_x: vec![Vec::new(); num_locations], - logical_y: vec![Vec::new(); num_locations], - logical_z: vec![Vec::new(); num_locations], + dem_output_x: vec![Vec::new(); num_locations], + dem_output_y: vec![Vec::new(); num_locations], + dem_output_z: vec![Vec::new(); num_locations], } } @@ -683,14 +848,14 @@ impl CompoundRecorder { } } - fn record_logical(&mut self, loc_idx: usize, pauli: Pauli, logical_idx: u32) { + fn record_dem_output(&mut self, loc_idx: usize, pauli: Pauli, dem_output_idx: u32) { if loc_idx >= self.num_locations { return; } match pauli { - Pauli::X => self.logical_x[loc_idx].push(logical_idx), - Pauli::Y => self.logical_y[loc_idx].push(logical_idx), - Pauli::Z => self.logical_z[loc_idx].push(logical_idx), + Pauli::X => self.dem_output_x[loc_idx].push(dem_output_idx), + Pauli::Y => self.dem_output_y[loc_idx].push(dem_output_idx), + Pauli::Z => self.dem_output_z[loc_idx].push(dem_output_idx), Pauli::I => {} } } @@ -712,15 +877,15 @@ impl CompoundRecorder { soa.detectors_z.push(det); } - // Add logical influences - for &log in &self.logical_x[loc_idx] { - soa.logicals_x.push(log); + // Add DEM-output influences + for &dem_output in &self.dem_output_x[loc_idx] { + soa.dem_outputs_x.push(dem_output); } - for &log in &self.logical_y[loc_idx] { - soa.logicals_y.push(log); + for &dem_output in &self.dem_output_y[loc_idx] { + soa.dem_outputs_y.push(dem_output); } - for &log in &self.logical_z[loc_idx] { - soa.logicals_z.push(log); + for &dem_output in &self.dem_output_z[loc_idx] { + soa.dem_outputs_z.push(dem_output); } soa.finish_location(); @@ -733,6 +898,7 @@ impl CompoundRecorder { #[cfg(test)] mod tests { use super::*; + use crate::fault_tolerance::propagator::DemOutputKind; use pecos_quantum::DagCircuit; #[test] @@ -801,17 +967,57 @@ mod tests { } #[test] - fn test_with_logical() { + fn test_with_pauli_operator() { let mut dag = DagCircuit::new(); dag.pz(&[2]); dag.cx(&[(0, 2)]); dag.mz(&[2]); - let builder = InfluenceBuilder::new(&dag).with_logical_z(vec![0]); // Track Z logical on qubit 0 + let builder = InfluenceBuilder::new(&dag).with_z(&[0]); // Track Z logical on qubit 0 let map = builder.build(); // Should track the logical - assert!(map.influences.max_logical_index().is_some()); + assert!(map.influences.max_dem_output_index().is_some()); + } + + #[test] + fn test_dem_output_metadata_accepts_pauli_string_and_normalizes_phase() { + use pecos_core::{Pauli, QuarterPhase}; + + let pauli = + PauliString::from_paulis_with_phase(QuarterPhase::MinusI, &[Pauli::X, Pauli::Z]); + let metadata = DemOutputMetadata::tracked_operator(pauli).with_label("xz"); + + assert_eq!(metadata.kind, DemOutputKind::TrackedOperator); + assert_eq!(metadata.label.as_deref(), Some("xz")); + assert_eq!(metadata.pauli.phase(), QuarterPhase::PlusOne); + assert_eq!(metadata.pauli.to_sparse_str(), "+X0 Z1"); + } + + #[test] + fn test_circuit_annotation_dem_output_metadata_tracks_only_operator_annotations() { + use pecos_core::pauli::constructors::X; + + let mut dag = DagCircuit::new(); + dag.pz(&[0]); + dag.h(&[0]); + let meas = dag.mz(&[0]); + dag.observable_labeled("record_obs", &[meas[0]]); + dag.pauli_operator_labeled("track_x", X(0)); + + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + assert_eq!(map.num_dem_outputs(), 0); + assert_eq!(map.num_tracked_ops(), 1); + assert_eq!(map.dem_output_metadata.len(), 1); + assert_eq!( + map.dem_output_metadata[0].kind, + DemOutputKind::TrackedOperator + ); + assert_eq!(map.dem_output_metadata[0].label.as_deref(), Some("track_x")); + assert_eq!(map.dem_output_metadata[0].pauli.to_sparse_str(), "+X0"); } } diff --git a/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs b/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs new file mode 100644 index 000000000..93ab21133 --- /dev/null +++ b/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs @@ -0,0 +1,471 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Maximum likelihood lookup table decoder. +//! +//! Builds a decoder by enumerating fault combinations up to a given weight, +//! computing their probabilities from a noise model, and for each syndrome +//! pattern choosing the most likely observable outcome. +//! +//! # Example +//! +//! ```ignore +//! use pecos_qec::fault_tolerance::lookup_decoder::LookupDecoder; +//! +//! let map = InfluenceBuilder::new(&dag) +//! .with_circuit_annotations(&dag) +//! .build(); +//! let noise = NoiseConfig::uniform(0.001); +//! +//! let decoder = LookupDecoder::build(&map, &noise, 3); +//! let result = decoder.decode(&[0, 2]); // syndrome: detectors 0 and 2 fired +//! println!("corrections: {:?}", result.corrections); +//! ``` + +use super::dem_builder::NoiseConfig; +use super::propagator::dag::{DagFaultInfluenceMap, DagSpacetimeLocation, GateFaultLocation}; +use pecos_core::gate_type::GateType; +use std::collections::BTreeMap; + +/// Maximum likelihood lookup table decoder. +/// +/// Maps syndrome patterns (sets of fired detectors) to the most likely +/// observable correction (which observables to flip). +#[derive(Debug, Clone)] +pub struct LookupDecoder { + /// Syndrome -> most likely observable flip pattern. + table: BTreeMap, Vec>, + /// DEM output IDs classified as observables. + observable_dem_outputs: Vec, + /// Maximum fault weight enumerated. + max_weight: usize, + /// Total probability mass accounted for (weight 0 through `max_weight`). + accounted_probability: f64, +} + +/// Result of decoding a syndrome. +#[derive(Debug, Clone)] +pub struct DecoderResult { + /// Which observables should be flipped (ML correction). + pub corrections: Vec, + /// Whether this syndrome was seen during enumeration. + pub known_syndrome: bool, + /// Whether any detector fired (non-empty syndrome). + /// For detection codes (d=2), discard shots where this is true. + pub detected: bool, +} + +impl LookupDecoder { + /// Build a lookup decoder by enumerating faults up to the given weight. + /// + /// Uses the standard per-gate circuit noise model: each gate faults with + /// probability p, and each non-identity Pauli is equally likely (p/3 for + /// 1-qubit, p/15 for 2-qubit). Idle gates with T1/T2 use biased noise. + #[must_use] + pub fn build(map: &DagFaultInfluenceMap, noise: &NoiseConfig, max_weight: usize) -> Self { + let observable_dem_outputs = observable_dem_output_indices(map); + let num_observables = observable_dem_outputs.len(); + + let loc_probs = compute_location_probs(&map.locations, noise); + let locs = map.gate_fault_locations(); + + // Pre-compute events and no-fault probabilities per gate location. + // + // For PZ/MZ gates, Z faults are physically no-ops. Their probability + // is absorbed into the no-fault probability so the total sums to 1.0. + // + // The combo probability uses a ratio approach: + // base_prob = product of no_fault(i) over all locations + // combo_prob = base_prob * product of (event_prob / no_fault) for participating locs + let mut loc_no_fault_probs: Vec = Vec::with_capacity(locs.len()); + let mut loc_events: Vec> = Vec::with_capacity(locs.len()); + + for loc in &locs { + let p = gate_location_prob(loc, &loc_probs, &map.locations); + + let events = loc.all_events(); + let num_physical_events = events.len(); + + // For idle gates with T1/T2, compute biased per-Pauli probabilities + let idle_pauli_probs = if loc.gate_type == GateType::Idle { + let duration = map + .locations + .iter() + .find(|l| l.node == loc.node && l.before == loc.before) + .map_or(1, |l| l.idle_duration.max(1)); + // Duration values are small integers; precision loss is not a concern. + #[allow(clippy::cast_precision_loss)] + Some(noise.idle_pauli_probs(duration as f64)) + } else { + None + }; + + let n_qubits = loc.num_qubits(); + let custom_weights = if idle_pauli_probs.is_some() { + None + } else if n_qubits == 1 { + noise.p1_weights.as_ref() + } else { + noise.p2_weights.as_ref() + }; + + let event_probs: Vec = if let Some(pp) = &idle_pauli_probs { + events + .iter() + .map(|event| { + let pauli = event + .pauli + .paulis() + .first() + .map_or(pecos_core::Pauli::I, |&(pa, _)| pa); + match pauli { + pecos_core::Pauli::X => pp.px, + pecos_core::Pauli::Y => pp.py, + pecos_core::Pauli::Z => pp.pz, + pecos_core::Pauli::I => 0.0, + } + }) + .collect() + } else if let Some(weights) = custom_weights { + events + .iter() + .map(|event| p * weights.weight_for(&event.pauli)) + .collect() + } else { + // Event count is a small integer; precision loss is not a concern. + #[allow(clippy::cast_precision_loss)] + let per_event = if num_physical_events > 0 { + p / num_physical_events as f64 + } else { + 0.0 + }; + vec![per_event; events.len()] + }; + + // No-fault = 1 - sum(event probs), absorbing filtered Paulis + let total_event_prob: f64 = event_probs.iter().sum(); + let no_fault = (1.0 - total_event_prob).max(0.0); + + let event_data: Vec = events + .into_iter() + .zip(event_probs) + .map(|(event, prob)| { + let ratio = if no_fault > 0.0 { + prob / no_fault + } else { + prob + }; + EventData { + prob: ratio, + detectors: event.detectors, + dem_outputs: event.dem_outputs, + } + }) + .collect(); + + loc_no_fault_probs.push(no_fault); + loc_events.push(event_data); + } + + // Accumulate: syndrome -> per-observable (flip_prob, noflip_prob) + let mut syndrome_data: BTreeMap, Vec<(f64, f64)>> = BTreeMap::new(); + + // Base probability: all locations no-fault + let base_prob: f64 = loc_no_fault_probs.iter().product(); + + // Weight 0: no faults. Empty syndrome, no observable flips. + { + let entry = syndrome_data + .entry(Vec::new()) + .or_insert_with(|| vec![(0.0, 0.0); num_observables]); + for w in entry.iter_mut() { + w.1 += base_prob; // no flip + } + } + + // Weight 1..max_weight + // Start with base_prob (all no-fault). Each event replaces a location's + // no-fault factor with the event factor via the pre-computed ratio. + let combo_state = ComboState { + prob: base_prob, + detectors: Vec::new(), + dem_outputs: Vec::new(), + }; + + for weight in 1..=max_weight { + enumerate_combos( + &loc_events, + weight, + 0, + &combo_state, + &observable_dem_outputs, + &mut syndrome_data, + ); + } + + // Compute total accounted probability. + // For each syndrome, the total probability is flip + noflip for any single + // observable channel (they all see the same total probability for that syndrome). + let accounted_probability: f64 = syndrome_data + .values() + .map(|weights| weights.first().map_or(0.0, |&(f, nf)| f + nf)) + .sum(); + + // Build ML decision table + let table = syndrome_data + .into_iter() + .map(|(syndrome, weights)| { + let corrections: Vec = weights + .iter() + .map(|&(flip, noflip)| flip > noflip) + .collect(); + (syndrome, corrections) + }) + .collect(); + + Self { + table, + observable_dem_outputs, + max_weight, + accounted_probability, + } + } + + /// Decode a syndrome given as detector indices. + #[must_use] + pub fn decode(&self, syndrome: &[u32]) -> DecoderResult { + let mut key: Vec = syndrome.to_vec(); + key.sort_unstable(); + let detected = !key.is_empty(); + + if let Some(corrections) = self.table.get(&key) { + DecoderResult { + corrections: corrections.clone(), + known_syndrome: true, + detected, + } + } else { + DecoderResult { + corrections: vec![false; self.observable_dem_outputs.len()], + known_syndrome: false, + detected, + } + } + } + + /// Decode from a boolean detector vector. + #[must_use] + pub fn decode_from_bools(&self, detectors: &[bool]) -> DecoderResult { + let syndrome: Vec = detectors + .iter() + .enumerate() + .filter_map(|(i, &fired)| { + if fired { + #[allow(clippy::cast_possible_truncation)] + Some(i as u32) + } else { + None + } + }) + .collect(); + self.decode(&syndrome) + } + + /// Number of distinct syndrome patterns in the table. + #[must_use] + pub fn num_syndromes(&self) -> usize { + self.table.len() + } + + /// Maximum fault weight that was enumerated. + #[must_use] + pub fn max_weight(&self) -> usize { + self.max_weight + } + + /// Number of observable channels. + #[must_use] + pub fn num_observables(&self) -> usize { + self.observable_dem_outputs.len() + } + + /// DEM output IDs classified as observables, in correction-vector order. + #[must_use] + pub fn observable_dem_output_indices(&self) -> &[u32] { + &self.observable_dem_outputs + } + + /// Estimated upper bound on the probability mass NOT accounted for + /// due to weight truncation. + /// + /// This bounds the total probability of fault combinations with + /// weight > `max_weight`. For low noise rates, this is small. + /// If it's large (> 0.01), consider increasing `max_weight`. + #[must_use] + pub fn truncation_bound(&self) -> f64 { + (1.0 - self.accounted_probability).max(0.0) + } + + /// Total probability mass accounted for (weights 0 through `max_weight`). + /// + /// Should be close to 1.0 for low noise rates with sufficient `max_weight`. + #[must_use] + pub fn accounted_probability(&self) -> f64 { + self.accounted_probability + } +} + +// ============================================================================ +// Internal types and helpers +// ============================================================================ + +struct EventData { + prob: f64, + detectors: Vec, + dem_outputs: Vec, +} + +#[derive(Clone)] +struct ComboState { + prob: f64, + detectors: Vec, + dem_outputs: Vec, +} + +impl ComboState { + /// Compose with a new event: XOR detectors/DEM outputs, multiply prob. + fn compose(&self, event: &EventData) -> Self { + let mut detectors = self.detectors.clone(); + xor_into(&mut detectors, &event.detectors); + let mut dem_outputs = self.dem_outputs.clone(); + xor_into(&mut dem_outputs, &event.dem_outputs); + Self { + prob: self.prob * event.prob, + detectors, + dem_outputs, + } + } +} + +/// Symmetric difference (XOR) of sorted u32 vecs. +fn xor_into(acc: &mut Vec, other: &[u32]) { + if other.is_empty() { + return; + } + if acc.is_empty() { + acc.extend_from_slice(other); + return; + } + let mut result = Vec::with_capacity(acc.len() + other.len()); + let (mut i, mut j) = (0, 0); + while i < acc.len() && j < other.len() { + match acc[i].cmp(&other[j]) { + std::cmp::Ordering::Less => { + result.push(acc[i]); + i += 1; + } + std::cmp::Ordering::Greater => { + result.push(other[j]); + j += 1; + } + std::cmp::Ordering::Equal => { + i += 1; + j += 1; + } + } + } + result.extend_from_slice(&acc[i..]); + result.extend_from_slice(&other[j..]); + *acc = result; +} + +/// Recursive combination enumeration with probability tracking. +fn enumerate_combos( + loc_events: &[Vec], + remaining: usize, + start_loc: usize, + state: &ComboState, + observable_dem_outputs: &[u32], + syndrome_data: &mut BTreeMap, Vec<(f64, f64)>>, +) { + if remaining == 0 { + let mut syndrome = state.detectors.clone(); + syndrome.sort_unstable(); + + let entry = syndrome_data + .entry(syndrome) + .or_insert_with(|| vec![(0.0, 0.0); observable_dem_outputs.len()]); + + for (&observable_id, weights) in observable_dem_outputs.iter().zip(entry.iter_mut()) { + let flipped = state.dem_outputs.contains(&observable_id); + if flipped { + weights.0 += state.prob; + } else { + weights.1 += state.prob; + } + } + return; + } + + for loc_idx in start_loc..loc_events.len() { + for event in &loc_events[loc_idx] { + let next_state = state.compose(event); + enumerate_combos( + loc_events, + remaining - 1, + loc_idx + 1, + &next_state, + observable_dem_outputs, + syndrome_data, + ); + } + } +} + +/// Compute per-location error probabilities from noise config. +fn compute_location_probs(locations: &[DagSpacetimeLocation], noise: &NoiseConfig) -> Vec { + super::dem_builder::sampler::compute_location_probs_from_noise(locations, noise) +} + +/// Get the per-qubit error probability for a gate fault location. +/// +/// Since `gate_fault_locations` groups per-qubit locations, all per-qubit +/// locations within a gate have the same gate-type-based probability. +fn gate_location_prob( + loc: &GateFaultLocation<'_>, + loc_probs: &[f64], + all_locations: &[DagSpacetimeLocation], +) -> f64 { + // Find any per-qubit location in the influence map for this gate + for (i, l) in all_locations.iter().enumerate() { + if l.node == loc.node && l.before == loc.before { + return loc_probs[i]; + } + } + 0.0 +} + +fn observable_dem_output_indices(map: &DagFaultInfluenceMap) -> Vec { + let num_dem_outputs = map.influences.max_dem_output_index().map_or(0, |i| i + 1); + if map.dem_output_metadata.is_empty() { + return (0..num_dem_outputs as u32).collect(); + } + + map.dem_output_metadata + .iter() + .enumerate() + .filter_map(|(idx, metadata)| { + (idx < num_dem_outputs && metadata.kind == super::propagator::DemOutputKind::Observable) + .then_some(idx as u32) + }) + .collect() +} diff --git a/crates/pecos-qec/src/fault_tolerance/noisy_sampler.rs b/crates/pecos-qec/src/fault_tolerance/noisy_sampler.rs deleted file mode 100644 index 7dca682dd..000000000 --- a/crates/pecos-qec/src/fault_tolerance/noisy_sampler.rs +++ /dev/null @@ -1,692 +0,0 @@ -//! Noisy Measurement Sampler using Precomputed Influence Maps -//! -//! This module provides efficient sampling of noisy measurement outcomes using -//! backward-propagated influence maps. Instead of simulating the full circuit -//! for each shot, we: -//! -//! 1. Precompute which fault locations affect which detectors/logicals -//! 2. For each shot, sample which faults fire -//! 3. Use O(1) lookups to find which detectors/logicals flip -//! -//! This approach is O(shots × `fault_locations`) instead of O(shots × `circuit_depth`), -//! providing significant speedup for noisy QEC simulations. -//! -//! # Example -//! -//! ``` -//! use pecos_qec::fault_tolerance::noisy_sampler::{NoisySampler, UniformNoiseModel}; -//! use pecos_qec::fault_tolerance::DagFaultAnalyzer; -//! use pecos_quantum::DagCircuit; -//! -//! // Build a simple circuit -//! let mut dag = DagCircuit::new(); -//! dag.pz(&[2]); -//! dag.cx(&[(0, 2)]); -//! dag.cx(&[(1, 2)]); -//! dag.mz(&[2]); -//! -//! // Build influence map (precomputation) -//! let analyzer = DagFaultAnalyzer::new(&dag); -//! let influence_map = analyzer.build_influence_map(); -//! -//! // Create noise model (uniform depolarizing) -//! let noise = UniformNoiseModel::depolarizing(0.001); -//! -//! // Sample many shots -//! let mut sampler = NoisySampler::new(&influence_map, noise, 42); -//! let results = sampler.sample(100); -//! -//! // Analyze results -//! for shot in &results { -//! if shot.has_logical_error() { -//! // ... -//! } -//! } -//! ``` - -use super::propagator::Pauli; -use super::propagator::dag::DagFaultInfluenceMap; -use pecos_random::rng_ext::RngProbabilityExt; -use pecos_random::{PecosRng, Rng}; -use std::collections::BTreeSet; - -/// Result from a single shot of noisy sampling. -#[derive(Debug, Clone)] -pub struct ShotResult { - /// Detectors that flipped (indices into `influence_map.detectors`). - pub detector_flips: Vec, - /// Logicals that flipped (indices). - pub logical_flips: Vec, - /// Number of faults that fired in this shot. - pub fault_count: usize, -} - -impl ShotResult { - /// Create an empty result. - #[must_use] - pub fn new() -> Self { - Self { - detector_flips: Vec::new(), - logical_flips: Vec::new(), - fault_count: 0, - } - } - - /// Check if any logical error occurred. - #[inline] - #[must_use] - pub fn has_logical_error(&self) -> bool { - !self.logical_flips.is_empty() - } - - /// Check if any syndrome was triggered. - #[inline] - #[must_use] - pub fn has_syndrome(&self) -> bool { - !self.detector_flips.is_empty() - } - - /// Check if this is an undetectable logical error. - #[inline] - #[must_use] - pub fn is_undetectable_logical_error(&self) -> bool { - self.has_logical_error() && !self.has_syndrome() - } -} - -impl Default for ShotResult { - fn default() -> Self { - Self::new() - } -} - -/// Trait for noise models that can sample faults at each location. -pub trait NoiseModel { - /// Sample a Pauli fault at the given location. - /// - /// Returns `Pauli::I` for no fault, or `X/Y/Z` for a fault. - fn sample_fault(&mut self, loc_idx: usize, rng: &mut impl Rng) -> Pauli; - - /// Get the total error probability at a location (for statistics). - fn error_probability(&self, loc_idx: usize) -> f64; -} - -/// Uniform depolarizing noise model. -/// -/// Same error probability at every location. With probability p, -/// applies X, Y, or Z with equal probability (p/3 each). -#[derive(Debug, Clone)] -pub struct UniformNoiseModel { - /// Total error probability per location. - p_error: f64, - /// Threshold for error occurrence (`p_error` * `u64::MAX`). - threshold: u64, -} - -impl UniformNoiseModel { - /// Create a uniform noise model with the given error probability. - #[must_use] - pub fn new(p_error: f64) -> Self { - #[allow( - clippy::cast_sign_loss, - clippy::cast_possible_truncation, - clippy::cast_precision_loss - )] - // probability in [0,1] so product fits in u64 - let threshold = (p_error * u64::MAX as f64) as u64; - Self { p_error, threshold } - } - - /// Create a depolarizing noise model (convenience alias). - #[must_use] - pub fn depolarizing(p_error: f64) -> Self { - Self::new(p_error) - } -} - -impl NoiseModel for UniformNoiseModel { - fn sample_fault(&mut self, _loc_idx: usize, rng: &mut impl Rng) -> Pauli { - let rand = rng.next_u64(); - if rand < self.threshold { - // Error occurred, sample which Pauli - match (rng.next_u32() % 3) as u8 { - 0 => Pauli::X, - 1 => Pauli::Y, - _ => Pauli::Z, - } - } else { - Pauli::I - } - } - - fn error_probability(&self, _loc_idx: usize) -> f64 { - self.p_error - } -} - -/// Per-location noise model with different probabilities. -/// -/// Each location can have different error rates. -#[derive(Debug, Clone)] -pub struct PerLocationNoiseModel { - /// Error probabilities per location. - probabilities: Vec, - /// Precomputed thresholds. - thresholds: Vec, -} - -impl PerLocationNoiseModel { - /// Create from a vector of error probabilities (one per location). - #[must_use] - pub fn new(probabilities: Vec) -> Self { - let thresholds = probabilities - .iter() - .map(|&p| { - #[allow( - clippy::cast_sign_loss, - clippy::cast_possible_truncation, - clippy::cast_precision_loss - )] - // probability in [0,1] so product fits in u64 - { - (p * u64::MAX as f64) as u64 - } - }) - .collect(); - Self { - probabilities, - thresholds, - } - } -} - -impl NoiseModel for PerLocationNoiseModel { - fn sample_fault(&mut self, loc_idx: usize, rng: &mut impl Rng) -> Pauli { - let threshold = self.thresholds.get(loc_idx).copied().unwrap_or(0); - let rand = rng.next_u64(); - if rand < threshold { - match (rng.next_u32() % 3) as u8 { - 0 => Pauli::X, - 1 => Pauli::Y, - _ => Pauli::Z, - } - } else { - Pauli::I - } - } - - fn error_probability(&self, loc_idx: usize) -> f64 { - self.probabilities.get(loc_idx).copied().unwrap_or(0.0) - } -} - -/// Noisy measurement sampler using precomputed influence maps. -/// -/// This provides efficient sampling by using O(1) lookups from the -/// influence map instead of full circuit simulation. -pub struct NoisySampler<'a, N: NoiseModel> { - /// Reference to the precomputed influence map. - influence_map: &'a DagFaultInfluenceMap, - /// Noise model for sampling faults. - noise_model: N, - /// Random number generator. - rng: PecosRng, - /// Number of fault locations. - num_locations: usize, - /// Number of detectors. - num_detectors: usize, - /// Number of logicals (derived from influence map). - num_logicals: usize, -} - -impl<'a, N: NoiseModel> NoisySampler<'a, N> { - /// Create a new noisy sampler. - /// - /// # Arguments - /// * `influence_map` - Precomputed influence map from backward propagation - /// * `noise_model` - Noise model for sampling faults - /// * `seed` - RNG seed for reproducibility - pub fn new(influence_map: &'a DagFaultInfluenceMap, noise_model: N, seed: u64) -> Self { - let num_locations = influence_map.locations.len(); - let num_detectors = influence_map.detectors.len(); - - // Estimate num_logicals from the influence map - // (could be stored explicitly in the map) - let num_logicals = influence_map - .influences - .max_logical_index() - .map_or(0, |i| i + 1); - - Self { - influence_map, - noise_model, - rng: PecosRng::seed_from_u64(seed), - num_locations, - num_detectors, - num_logicals, - } - } - - /// Sample a single shot. - pub fn sample_one(&mut self) -> ShotResult { - // Track which detectors/logicals have flipped (using XOR) - let mut detector_flip_counts: Vec = vec![0; self.num_detectors]; - let mut logical_flip_counts: Vec = vec![0; self.num_logicals.max(1)]; - let mut fault_count = 0; - - // Sample each fault location - for loc_idx in 0..self.num_locations { - let pauli = self.noise_model.sample_fault(loc_idx, &mut self.rng); - - if pauli != Pauli::I { - fault_count += 1; - - // Get affected detectors (O(1) lookup) - let detectors = self - .influence_map - .get_detector_indices(loc_idx, pauli.as_u8()); - for &det_idx in detectors { - detector_flip_counts[det_idx as usize] ^= 1; - } - - // Get affected logicals (O(1) lookup) - let logicals = self - .influence_map - .get_logical_indices(loc_idx, pauli.as_u8()); - for &log_idx in logicals { - if (log_idx as usize) < logical_flip_counts.len() { - logical_flip_counts[log_idx as usize] ^= 1; - } - } - } - } - - // Collect indices that ended up flipped (odd count) - let detector_flips: Vec = detector_flip_counts - .iter() - .enumerate() - .filter(|(_, c)| **c == 1) - .map(|(i, _)| { - #[allow(clippy::cast_possible_truncation)] // detector index fits in u32 - { - i as u32 - } - }) - .collect(); - - let logical_flips: Vec = logical_flip_counts - .iter() - .enumerate() - .filter(|(_, c)| **c == 1) - .map(|(i, _)| { - #[allow(clippy::cast_possible_truncation)] // logical index fits in u32 - { - i as u32 - } - }) - .collect(); - - ShotResult { - detector_flips, - logical_flips, - fault_count, - } - } - - /// Sample multiple shots. - pub fn sample(&mut self, num_shots: usize) -> Vec { - (0..num_shots).map(|_| self.sample_one()).collect() - } - - /// Sample and compute statistics. - pub fn sample_statistics(&mut self, num_shots: usize) -> SamplingStatistics { - let mut stats = SamplingStatistics::new(); - - for _ in 0..num_shots { - let result = self.sample_one(); - stats.record(&result); - } - - stats - } - - /// Get the number of fault locations. - pub fn num_locations(&self) -> usize { - self.num_locations - } - - /// Get the number of detectors. - pub fn num_detectors(&self) -> usize { - self.num_detectors - } -} - -/// Statistics from sampling. -#[derive(Debug, Clone)] -pub struct SamplingStatistics { - /// Total number of shots. - pub total_shots: usize, - /// Number of shots with logical errors. - pub logical_error_count: usize, - /// Number of shots with syndromes (detector flips). - pub syndrome_count: usize, - /// Number of undetectable logical errors. - pub undetectable_count: usize, - /// Total faults across all shots. - pub total_faults: usize, -} - -impl SamplingStatistics { - /// Create empty statistics. - #[must_use] - pub fn new() -> Self { - Self { - total_shots: 0, - logical_error_count: 0, - syndrome_count: 0, - undetectable_count: 0, - total_faults: 0, - } - } - - /// Record a shot result. - pub fn record(&mut self, result: &ShotResult) { - self.total_shots += 1; - self.total_faults += result.fault_count; - - if result.has_logical_error() { - self.logical_error_count += 1; - } - if result.has_syndrome() { - self.syndrome_count += 1; - } - if result.is_undetectable_logical_error() { - self.undetectable_count += 1; - } - } - - /// Logical error rate. - #[must_use] - #[allow(clippy::cast_precision_loss)] // rate calculation - pub fn logical_error_rate(&self) -> f64 { - if self.total_shots == 0 { - 0.0 - } else { - self.logical_error_count as f64 / self.total_shots as f64 - } - } - - /// Syndrome rate (fraction of shots with non-trivial syndrome). - #[must_use] - #[allow(clippy::cast_precision_loss)] // rate calculation - pub fn syndrome_rate(&self) -> f64 { - if self.total_shots == 0 { - 0.0 - } else { - self.syndrome_count as f64 / self.total_shots as f64 - } - } - - /// Undetectable error rate. - #[must_use] - #[allow(clippy::cast_precision_loss)] // rate calculation - pub fn undetectable_rate(&self) -> f64 { - if self.total_shots == 0 { - 0.0 - } else { - self.undetectable_count as f64 / self.total_shots as f64 - } - } - - /// Average faults per shot. - #[must_use] - #[allow(clippy::cast_precision_loss)] // rate calculation - pub fn average_faults(&self) -> f64 { - if self.total_shots == 0 { - 0.0 - } else { - self.total_faults as f64 / self.total_shots as f64 - } - } -} - -impl Default for SamplingStatistics { - fn default() -> Self { - Self::new() - } -} - -// ============================================================================ -// Optimized Sampler using PecosRng batching and sparse tracking -// ============================================================================ - -/// Optimized noisy sampler using `PecosRng` batching and sparse flip tracking. -/// -/// Key optimizations over [`NoisySampler`]: -/// 1. Uses `check_probability_indices()` to get sparse list of fault locations -/// 2. Uses `BTreeSet` for flip tracking instead of dense `Vec` -/// 3. Reuses buffers across shots to avoid allocation overhead -/// -/// For low error rates (p < 0.01), this can be 2-3x faster than the standard sampler. -pub struct FastNoisySampler<'a> { - /// Reference to the precomputed influence map. - influence_map: &'a DagFaultInfluenceMap, - /// Error probability. - p_error: f64, - /// Precomputed threshold for probability check. - threshold: u64, - /// Random number generator (`PecosRng` for batching). - rng: PecosRng, - /// Number of fault locations. - num_locations: usize, - /// Number of logicals. - num_logicals: usize, - /// Reusable buffer for detector flips (sparse). - detector_flips_buffer: BTreeSet, - /// Reusable buffer for logical flips (sparse). - logical_flips_buffer: BTreeSet, -} - -impl<'a> FastNoisySampler<'a> { - /// Create a new optimized sampler. - /// - /// # Arguments - /// * `influence_map` - Precomputed influence map - /// * `p_error` - Uniform depolarizing error probability - /// * `seed` - RNG seed - #[must_use] - pub fn new(influence_map: &'a DagFaultInfluenceMap, p_error: f64, seed: u64) -> Self { - let num_locations = influence_map.locations.len(); - let num_logicals = influence_map - .influences - .max_logical_index() - .map_or(0, |i| i + 1); - - let rng = PecosRng::seed_from_u64(seed); - let threshold = rng.probability_threshold(p_error); - - Self { - influence_map, - p_error, - threshold, - rng, - num_locations, - num_logicals, - detector_flips_buffer: BTreeSet::new(), - logical_flips_buffer: BTreeSet::new(), - } - } - - /// Sample a single shot using sparse tracking. - pub fn sample_one(&mut self) -> ShotResult { - // Clear reusable buffers - self.detector_flips_buffer.clear(); - self.logical_flips_buffer.clear(); - - // Get sparse list of fault locations using batched RNG - let fault_indices = self - .rng - .check_probability_indices(self.threshold, self.num_locations); - - let fault_count = fault_indices.len(); - - // Process only the faulted locations - for loc_idx in fault_indices { - // Select Pauli type: 0=X, 1=Y, 2=Z - let pauli_idx = self.rng.random_index_3(); - let pauli = match pauli_idx { - 0 => Pauli::X, - 1 => Pauli::Y, - _ => Pauli::Z, - }; - - // Toggle affected detectors (XOR via HashSet toggle) - let detectors = self - .influence_map - .get_detector_indices(loc_idx, pauli.as_u8()); - for &det_idx in detectors { - if !self.detector_flips_buffer.remove(&det_idx) { - self.detector_flips_buffer.insert(det_idx); - } - } - - // Toggle affected logicals - let logicals = self - .influence_map - .get_logical_indices(loc_idx, pauli.as_u8()); - for &log_idx in logicals { - if (log_idx as usize) < self.num_logicals - && !self.logical_flips_buffer.remove(&log_idx) - { - self.logical_flips_buffer.insert(log_idx); - } - } - } - - // Collect results - let detector_flips: Vec = self.detector_flips_buffer.iter().copied().collect(); - let logical_flips: Vec = self.logical_flips_buffer.iter().copied().collect(); - - ShotResult { - detector_flips, - logical_flips, - fault_count, - } - } - - /// Sample multiple shots. - pub fn sample(&mut self, num_shots: usize) -> Vec { - (0..num_shots).map(|_| self.sample_one()).collect() - } - - /// Sample and compute statistics. - pub fn sample_statistics(&mut self, num_shots: usize) -> SamplingStatistics { - let mut stats = SamplingStatistics::new(); - - for _ in 0..num_shots { - let result = self.sample_one(); - stats.record(&result); - } - - stats - } - - /// Get the error probability. - #[must_use] - pub fn p_error(&self) -> f64 { - self.p_error - } - - /// Get the number of fault locations. - #[must_use] - pub fn num_locations(&self) -> usize { - self.num_locations - } -} - -#[cfg(test)] -mod tests { - use super::*; - - // Mock influence map for testing - #[allow(dead_code)] - fn create_test_influence_map() -> DagFaultInfluenceMap { - DagFaultInfluenceMap::with_capacity(0) - } - - #[test] - fn test_uniform_noise_model() { - let mut noise = UniformNoiseModel::new(0.5); - let mut rng = PecosRng::seed_from_u64(42); - - let mut error_count = 0; - for _ in 0..1000 { - if noise.sample_fault(0, &mut rng) != Pauli::I { - error_count += 1; - } - } - - // Should be roughly 50% - assert!(error_count > 400 && error_count < 600); - } - - #[test] - fn test_per_location_noise_model() { - let probs = vec![0.0, 0.5, 1.0]; - let mut noise = PerLocationNoiseModel::new(probs); - let mut rng = PecosRng::seed_from_u64(42); - - // Location 0: never errors - for _ in 0..100 { - assert_eq!(noise.sample_fault(0, &mut rng), Pauli::I); - } - - // Location 2: always errors - for _ in 0..100 { - assert_ne!(noise.sample_fault(2, &mut rng), Pauli::I); - } - } - - #[test] - fn test_shot_result() { - let mut result = ShotResult::new(); - assert!(!result.has_logical_error()); - assert!(!result.has_syndrome()); - - result.logical_flips.push(0); - assert!(result.has_logical_error()); - assert!(result.is_undetectable_logical_error()); - - result.detector_flips.push(0); - assert!(!result.is_undetectable_logical_error()); - } - - #[test] - fn test_statistics() { - let mut stats = SamplingStatistics::new(); - - // Shot with no errors - stats.record(&ShotResult::new()); - - // Shot with syndrome only - let mut shot_with_syndrome = ShotResult::new(); - shot_with_syndrome.detector_flips.push(0); - stats.record(&shot_with_syndrome); - - // Shot with logical error - let mut shot_with_logical = ShotResult::new(); - shot_with_logical.logical_flips.push(0); - shot_with_logical.detector_flips.push(1); - stats.record(&shot_with_logical); - - // Shot with undetectable logical - let mut shot_undetectable = ShotResult::new(); - shot_undetectable.logical_flips.push(0); - stats.record(&shot_undetectable); - - assert_eq!(stats.total_shots, 4); - assert_eq!(stats.logical_error_count, 2); - assert_eq!(stats.syndrome_count, 2); - assert_eq!(stats.undetectable_count, 1); - } -} diff --git a/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs b/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs index 5ccfd34f4..f8a7aabfe 100644 --- a/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs +++ b/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs @@ -1073,45 +1073,62 @@ fn propagate_until_tick(circuit: &TickCircuit, fault: &PauliFault, until_tick: u for gate in tick.gates() { let qubits: Vec = gate.qubits.iter().copied().collect(); match gate.gate_type { - GateType::CX => { - if qubits.len() >= 2 { - prop.cx(&[(qubits[0], qubits[1])]); - } + GateType::CX if qubits.len() >= 2 => { + prop.cx(&[(qubits[0], qubits[1])]); } - GateType::CZ => { - if qubits.len() >= 2 { - prop.cz(&[(qubits[0], qubits[1])]); - } + GateType::CZ if qubits.len() >= 2 => { + prop.cz(&[(qubits[0], qubits[1])]); } - GateType::CY => { - if qubits.len() >= 2 { - prop.cy(&[(qubits[0], qubits[1])]); - } + GateType::CY if qubits.len() >= 2 => { + prop.cy(&[(qubits[0], qubits[1])]); } GateType::H => { - for q in &qubits { - prop.h(&[*q]); - } + prop.h(&qubits); } - GateType::SZ | GateType::SZdg => { - for q in &qubits { - prop.sz(&[*q]); - } + GateType::F => { + prop.f(&qubits); } - GateType::SX | GateType::SXdg => { - for q in &qubits { - prop.sx(&[*q]); - } + GateType::Fdg => { + prop.fdg(&qubits); } - GateType::SY | GateType::SYdg => { - for q in &qubits { - prop.sy(&[*q]); - } + GateType::SX => { + prop.sx(&qubits); } - GateType::SWAP => { - if qubits.len() >= 2 { - prop.swap(&[(qubits[0], qubits[1])]); - } + GateType::SXdg => { + prop.sxdg(&qubits); + } + GateType::SY => { + prop.sy(&qubits); + } + GateType::SYdg => { + prop.sydg(&qubits); + } + GateType::SZ => { + prop.sz(&qubits); + } + GateType::SZdg => { + prop.szdg(&qubits); + } + GateType::SWAP if qubits.len() >= 2 => { + prop.swap(&[(qubits[0], qubits[1])]); + } + GateType::SXX if qubits.len() >= 2 => { + prop.sxx(&[(qubits[0], qubits[1])]); + } + GateType::SXXdg if qubits.len() >= 2 => { + prop.sxxdg(&[(qubits[0], qubits[1])]); + } + GateType::SYY if qubits.len() >= 2 => { + prop.syy(&[(qubits[0], qubits[1])]); + } + GateType::SYYdg if qubits.len() >= 2 => { + prop.syydg(&[(qubits[0], qubits[1])]); + } + GateType::SZZ if qubits.len() >= 2 => { + prop.szz(&[(qubits[0], qubits[1])]); + } + GateType::SZZdg if qubits.len() >= 2 => { + prop.szzdg(&[(qubits[0], qubits[1])]); } _ => {} } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator.rs b/crates/pecos-qec/src/fault_tolerance/propagator.rs index a0c928436..2f130617b 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator.rs @@ -14,7 +14,7 @@ //! //! This module provides bidirectional Pauli propagation through quantum circuits, //! with specialized support for fault tolerance analysis. By propagating observables -//! backward from measurements/logicals, we can efficiently determine which faults +//! backward from measurements and tracked Pauli operators, we can efficiently determine which faults //! affect which detectors: //! //! 1. **Speed up fault enumeration** - O(1) lookup instead of `O(circuit_depth)` propagation @@ -44,7 +44,7 @@ //! let map = analyzer.build_influence_map(); //! //! // O(1) lookup: which measurements does a fault at location L flip? -//! let (has_syndrome, has_logical) = map.classify_fault(0, 1); // loc 0, X fault +//! let (has_syndrome, flips_tracked_op) = map.classify_fault(0, 1); // loc 0, X fault //! ``` //! //! # Concept @@ -96,7 +96,8 @@ pub mod types; pub use checker::InfluenceBasedChecker; pub use dag::{ BucketRecorder, CsrArray, DagFaultAnalyzer, DagFaultInfluenceMap, DagSpacetimeLocation, - FaultLocations, InfluencesSoA, InfluencesSoAStats, SoARecorderBuilder, + DemOutputKind, DemOutputMetadata, FaultCombo, FaultComponent, FaultEffect, FaultLocations, + GateFaultLocation, InfluencesSoA, InfluencesSoAStats, SoARecorderBuilder, }; pub use pauli::{ Direction, apply_gate, init_pauli_prop_with_fault, propagate_backward_from_tick, @@ -106,8 +107,8 @@ pub use pauli::{ pub use tick::TickFaultAnalyzer; pub use tick_soa::TickFaultAnalyzerSoA; pub use types::{ - DetectorId, DetectorIdx, FaultInfluence, FaultInfluenceMap, LocationId, LogicalId, LogicalIdx, - MeasurementId, NodeId, Pauli, + DemOutputIdx, DetectorId, DetectorIdx, FaultInfluence, FaultInfluenceMap, LocationId, + MeasurementId, NodeId, Pauli, TrackedOpId, TrackedOpIdx, }; // Internal imports @@ -199,7 +200,7 @@ pub trait InfluenceRecorder { /// clean separation between traversal and recording. #[derive(Debug)] pub struct PropagationContext<'a> { - /// Current Pauli observable being propagated. + /// Current Pauli operator being propagated. pub prop: PauliProp, /// Work buffers for traversal. pub buffers: &'a mut PropagatorWorkBuffers, @@ -218,17 +219,17 @@ impl<'a> PropagationContext<'a> { } } - /// Initializes the Pauli observable for a Z-basis measurement. + /// Initializes the Pauli operator for a Z-basis measurement. pub fn init_z_measurement(&mut self, qubit: usize) { self.prop.track_z(&[qubit]); } - /// Initializes the Pauli observable for an X-basis measurement. + /// Initializes the Pauli operator for an X-basis measurement. pub fn init_x_measurement(&mut self, qubit: usize) { self.prop.track_x(&[qubit]); } - /// Initializes the Pauli observable based on measurement basis. + /// Initializes the Pauli operator based on measurement basis. pub fn init_measurement(&mut self, qubit: usize, basis: u8) { if basis == 0 { self.prop.track_z(&[qubit]); @@ -354,7 +355,7 @@ impl InfluenceRecorder for CountingRecorder { if obs_x { self.by_pauli[3] += 1; // Z fault } - if obs_x || obs_z { + if obs_x ^ obs_z { self.by_pauli[2] += 1; // Y fault } } @@ -766,8 +767,8 @@ mod tests { // Get any fault location and check classification if let Some((loc, _)) = map.influences.iter().next() { - let (has_syndrome, has_logical) = checker.classify(loc, 1); // X fault - println!("Location {loc:?}: syndrome={has_syndrome}, logical={has_logical}"); + let (has_syndrome, flips_tracked_op) = checker.classify(loc, 1); // X fault + println!("Location {loc:?}: syndrome={has_syndrome}, tracked_op={flips_tracked_op}"); } } @@ -950,33 +951,36 @@ mod tests { } #[test] - fn test_backward_vs_forward_with_logicals() { - // Test that logical tracking works with backward propagation + fn test_backward_vs_forward_with_tracked_ops() { + // Test that tracked-operator propagation works with backward propagation let mut circuit = TickCircuit::new(); circuit.tick().pz(&[0, 1, 2]); circuit.tick().cx(&[(0, 2)]); circuit.tick().cx(&[(1, 2)]); circuit.tick().mz(&[2]); - // Define a simple logical Z = Z0 Z1 - let logicals: &[(&[usize], &[usize])] = &[(&[], &[0, 1])]; + // Define a simple tracked Z operator = Z0 Z1 + let tracked_ops: &[(&[usize], &[usize])] = &[(&[], &[0, 1])]; let propagator = TickFaultAnalyzer::new(&circuit); - let map = propagator.build_influence_map_with_logicals(logicals); + let map = propagator.build_influence_map_with_tracked_ops(tracked_ops); - // Check that logical tracking is populated - assert_eq!(map.logicals.len(), 1); + // Check that tracked-operator propagation is populated + assert_eq!(map.tracked_ops.len(), 1); - // X errors on data qubits should flip the logical - let mut found_logical_flip = false; + // X errors on data qubits should flip the tracked operator + let mut found_tracked_op_flip = false; for (loc, influence) in &map.influences { if loc.qubits.iter().any(|q| q.index() == 0 || q.index() == 1) - && !influence.logicals_for_pauli(1).is_empty() + && !influence.tracked_ops_for_pauli(1).is_empty() { - found_logical_flip = true; + found_tracked_op_flip = true; } } - assert!(found_logical_flip, "Should find X errors that flip logical"); + assert!( + found_tracked_op_flip, + "Should find X errors that flip tracked operator" + ); } #[test] @@ -1065,4 +1069,226 @@ mod tests { // Should have 2 measurements (2 rounds) assert_eq!(map.detectors.len(), 2); } + + fn pauli_signature(prop: &PauliProp, qubits: &[usize]) -> Vec<(bool, bool)> { + qubits + .iter() + .map(|&q| (prop.contains_x(q), prop.contains_z(q))) + .collect() + } + + fn pauli_prop_from_signature(signature: &[(bool, bool)]) -> PauliProp { + let mut prop = PauliProp::new(); + for (qubit, &(has_x, has_z)) in signature.iter().enumerate() { + if has_x { + prop.track_x(&[qubit]); + } + if has_z { + prop.track_z(&[qubit]); + } + } + prop + } + + fn add_standard_clifford_gate(circuit: &mut TickCircuit, gate_type: GateType) { + match gate_type { + GateType::I => { + circuit.tick().iden(&[0]); + } + GateType::X => { + circuit.tick().x(&[0]); + } + GateType::Y => { + circuit.tick().y(&[0]); + } + GateType::Z => { + circuit.tick().z(&[0]); + } + GateType::H => { + circuit.tick().h(&[0]); + } + GateType::F => { + circuit.tick().f(&[0]); + } + GateType::Fdg => { + circuit.tick().fdg(&[0]); + } + GateType::SX => { + circuit.tick().sx(&[0]); + } + GateType::SXdg => { + circuit.tick().sxdg(&[0]); + } + GateType::SY => { + circuit.tick().sy(&[0]); + } + GateType::SYdg => { + circuit.tick().sydg(&[0]); + } + GateType::SZ => { + circuit.tick().sz(&[0]); + } + GateType::SZdg => { + circuit.tick().szdg(&[0]); + } + GateType::CX => { + circuit.tick().cx(&[(0, 1)]); + } + GateType::CY => { + circuit.tick().cy(&[(0, 1)]); + } + GateType::CZ => { + circuit.tick().cz(&[(0, 1)]); + } + GateType::SXX => { + circuit.tick().sxx(&[(0, 1)]); + } + GateType::SXXdg => { + circuit.tick().sxxdg(&[(0, 1)]); + } + GateType::SYY => { + circuit.tick().syy(&[(0, 1)]); + } + GateType::SYYdg => { + circuit.tick().syydg(&[(0, 1)]); + } + GateType::SZZ => { + circuit.tick().szz(&[(0, 1)]); + } + GateType::SZZdg => { + circuit.tick().szzdg(&[(0, 1)]); + } + GateType::SWAP => { + circuit.tick().swap(&[(0, 1)]); + } + _ => unreachable!("not a standard Clifford gate: {gate_type:?}"), + } + } + + fn assert_pauli_signature_after_gate( + gate_type: GateType, + input: [(bool, bool); 2], + expected: [(bool, bool); 2], + ) { + let mut circuit = TickCircuit::new(); + add_standard_clifford_gate(&mut circuit, gate_type); + + let mut prop = pauli_prop_from_signature(&input); + propagate_through_circuit(&circuit, &mut prop, Direction::Forward); + + assert_eq!( + pauli_signature(&prop, &[0, 1]), + expected, + "{gate_type:?} should map {input:?} to {expected:?} up to Pauli phase" + ); + } + + #[test] + fn test_standard_clifford_pauli_conjugation_tables() { + const I: (bool, bool) = (false, false); + const X: (bool, bool) = (true, false); + const Z: (bool, bool) = (false, true); + const Y: (bool, bool) = (true, true); + + assert_pauli_signature_after_gate(GateType::H, [X, I], [Z, I]); + assert_pauli_signature_after_gate(GateType::H, [Z, I], [X, I]); + assert_pauli_signature_after_gate(GateType::F, [X, I], [Y, I]); + assert_pauli_signature_after_gate(GateType::F, [Y, I], [Z, I]); + assert_pauli_signature_after_gate(GateType::F, [Z, I], [X, I]); + assert_pauli_signature_after_gate(GateType::Fdg, [X, I], [Z, I]); + assert_pauli_signature_after_gate(GateType::Fdg, [Y, I], [X, I]); + assert_pauli_signature_after_gate(GateType::Fdg, [Z, I], [Y, I]); + assert_pauli_signature_after_gate(GateType::SX, [Z, I], [Y, I]); + assert_pauli_signature_after_gate(GateType::SY, [X, I], [Z, I]); + assert_pauli_signature_after_gate(GateType::SZ, [X, I], [Y, I]); + + assert_pauli_signature_after_gate(GateType::CX, [X, I], [X, X]); + assert_pauli_signature_after_gate(GateType::CX, [I, Z], [Z, Z]); + assert_pauli_signature_after_gate(GateType::CY, [X, I], [X, Y]); + assert_pauli_signature_after_gate(GateType::CZ, [X, I], [X, Z]); + assert_pauli_signature_after_gate(GateType::SWAP, [X, Z], [Z, X]); + + assert_pauli_signature_after_gate(GateType::SXX, [Z, I], [Y, X]); + assert_pauli_signature_after_gate(GateType::SXX, [I, Z], [X, Y]); + assert_pauli_signature_after_gate(GateType::SYY, [X, I], [Z, Y]); + assert_pauli_signature_after_gate(GateType::SYY, [I, X], [Y, Z]); + assert_pauli_signature_after_gate(GateType::SZZ, [X, I], [Y, Z]); + assert_pauli_signature_after_gate(GateType::SZZ, [I, X], [Z, Y]); + + assert_pauli_signature_after_gate(GateType::SXXdg, [Z, I], [Y, X]); + assert_pauli_signature_after_gate(GateType::SYYdg, [X, I], [Z, Y]); + assert_pauli_signature_after_gate(GateType::SZZdg, [X, I], [Y, Z]); + } + + #[test] + fn test_rz_propagation_matches_sz() { + let mut rotated = TickCircuit::new(); + rotated.tick().rz(pecos_core::Angle64::QUARTER_TURN, &[0]); + + let mut simplified = TickCircuit::new(); + simplified.tick().sz(&[0]); + + let mut rotated_prop = PauliProp::new(); + rotated_prop.track_x(&[0]); + propagate_through_circuit(&rotated, &mut rotated_prop, Direction::Forward); + + let mut simplified_prop = PauliProp::new(); + simplified_prop.track_x(&[0]); + propagate_through_circuit(&simplified, &mut simplified_prop, Direction::Forward); + + assert_eq!( + pauli_signature(&rotated_prop, &[0]), + pauli_signature(&simplified_prop, &[0]) + ); + } + + #[test] + fn test_r1xy_propagation_matches_sx() { + let mut rotated = TickCircuit::new(); + rotated.tick().r1xy( + pecos_core::Angle64::QUARTER_TURN, + pecos_core::Angle64::ZERO, + &[0], + ); + + let mut simplified = TickCircuit::new(); + simplified.tick().sx(&[0]); + + let mut rotated_prop = PauliProp::new(); + rotated_prop.track_z(&[0]); + propagate_through_circuit(&rotated, &mut rotated_prop, Direction::Forward); + + let mut simplified_prop = PauliProp::new(); + simplified_prop.track_z(&[0]); + propagate_through_circuit(&simplified, &mut simplified_prop, Direction::Forward); + + assert_eq!( + pauli_signature(&rotated_prop, &[0]), + pauli_signature(&simplified_prop, &[0]) + ); + } + + #[test] + fn test_rzz_propagation_matches_szz() { + let mut rotated = TickCircuit::new(); + rotated + .tick() + .rzz(pecos_core::Angle64::QUARTER_TURN, &[(0, 1)]); + + let mut simplified = TickCircuit::new(); + simplified.tick().szz(&[(0, 1)]); + + let mut rotated_prop = PauliProp::new(); + rotated_prop.track_x(&[0]); + propagate_through_circuit(&rotated, &mut rotated_prop, Direction::Forward); + + let mut simplified_prop = PauliProp::new(); + simplified_prop.track_x(&[0]); + propagate_through_circuit(&simplified, &mut simplified_prop, Direction::Forward); + + assert_eq!( + pauli_signature(&rotated_prop, &[0, 1]), + pauli_signature(&simplified_prop, &[0, 1]) + ); + } } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/checker.rs b/crates/pecos-qec/src/fault_tolerance/propagator/checker.rs index 58f0bd5d6..4f95cd5ca 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/checker.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/checker.rs @@ -35,11 +35,12 @@ impl<'a> InfluenceBasedChecker<'a> { /// Classifies a fault at the given location with the given Pauli type. /// - /// For single-qubit locations, returns whether any qubit causes syndrome/logical. + /// For single-qubit locations, returns whether any qubit causes syndrome or + /// flips a tracked operator. /// For multi-qubit locations where the same Pauli is applied to all qubits, /// use `classify_uniform` which properly handles cancellation effects. /// - /// Returns (`has_syndrome`, `causes_logical_error`). + /// Returns (`has_syndrome`, `flips_tracked_op`). #[must_use] pub fn classify(&self, location: &SpacetimeLocation, pauli: u8) -> (bool, bool) { self.influence_map.classify_fault(location, pauli) @@ -53,7 +54,7 @@ impl<'a> InfluenceBasedChecker<'a> { /// For Y faults (single or multi-qubit), we decompose Y = XZ and combine the /// X and Z contributions with XOR semantics. /// - /// Returns (`has_syndrome`, `causes_logical_error`). + /// Returns (`has_syndrome`, `flips_tracked_op`). #[must_use] pub fn classify_uniform(&self, location: &SpacetimeLocation, pauli: u8) -> (bool, bool) { // Always use multi-qubit logic for Y faults (even single-qubit) @@ -77,10 +78,10 @@ impl<'a> InfluenceBasedChecker<'a> { }) } - /// Checks if a fault causes an undetectable logical error. + /// Checks if a fault silently flips a tracked operator. #[must_use] - pub fn is_undetectable_logical_error(&self, location: &SpacetimeLocation, pauli: u8) -> bool { - let (has_syndrome, has_logical) = self.classify(location, pauli); - !has_syndrome && has_logical + pub fn is_silent_tracked_op_flip(&self, location: &SpacetimeLocation, pauli: u8) -> bool { + let (has_syndrome, flips_tracked_op) = self.classify(location, pauli); + !has_syndrome && flips_tracked_op } } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs b/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs index 8f13a49b1..04300f5a5 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs @@ -48,18 +48,18 @@ //! let map = analyzer.build_influence_map(); //! //! // O(1) fault classification -//! let (has_syndrome, has_logical) = map.classify_fault(0, 1); // loc 0, X fault +//! let (has_syndrome, flips_dem_output) = map.classify_fault(0, 1); // loc 0, X fault //! ``` use super::{ DagPropagator, DetectorId, Direction, InfluenceRecorder, MeasurementId, Pauli, apply_gate, }; -use pecos_core::QubitId; use pecos_core::gate_type::GateType; +use pecos_core::{PauliString, QuarterPhase, QubitId}; use pecos_quantum::DagCircuit; use pecos_simulators::PauliProp; use smallvec::SmallVec; -use std::collections::BinaryHeap; +use std::collections::{BTreeMap, BinaryHeap}; /// Reusable work buffers for propagation, avoiding per-call allocation. pub struct PropagationBuffers { @@ -179,6 +179,7 @@ impl FaultLocations { qubits: self.qubits[i].iter().map(|&q| QubitId::from(q)).collect(), before: self.before[i], gate_type: self.gate_types[i], + idle_duration: 0, }) .collect() } @@ -202,6 +203,8 @@ pub struct DagSpacetimeLocation { pub before: bool, /// The type of gate at this location. pub gate_type: GateType, + /// Duration for idle gates (in abstract time units). 0 for non-idle gates. + pub idle_duration: u64, } // ============================================================================ @@ -348,14 +351,14 @@ pub struct InfluencesSoA { /// Detector indices flipped by Z faults (Pauli=3). pub detectors_z: CsrArray, - /// Logical indices flipped by X faults. - pub logicals_x: CsrArray, + /// DEM `L` DEM-output indices flipped by X faults. + pub dem_outputs_x: CsrArray, - /// Logical indices flipped by Y faults. - pub logicals_y: CsrArray, + /// DEM `L` DEM-output indices flipped by Y faults. + pub dem_outputs_y: CsrArray, - /// Logical indices flipped by Z faults. - pub logicals_z: CsrArray, + /// DEM `L` DEM-output indices flipped by Z faults. + pub dem_outputs_z: CsrArray, } impl InfluencesSoA { @@ -369,9 +372,9 @@ impl InfluencesSoA { detectors_x: CsrArray::with_capacity(num_locations, estimated_data), detectors_y: CsrArray::with_capacity(num_locations, estimated_data), detectors_z: CsrArray::with_capacity(num_locations, estimated_data), - logicals_x: CsrArray::with_capacity(num_locations, estimated_data / 4), - logicals_y: CsrArray::with_capacity(num_locations, estimated_data / 4), - logicals_z: CsrArray::with_capacity(num_locations, estimated_data / 4), + dem_outputs_x: CsrArray::with_capacity(num_locations, estimated_data / 4), + dem_outputs_y: CsrArray::with_capacity(num_locations, estimated_data / 4), + dem_outputs_z: CsrArray::with_capacity(num_locations, estimated_data / 4), } } @@ -387,15 +390,15 @@ impl InfluencesSoA { } } - /// Returns the logical indices for a location and Pauli type. + /// Returns the DEM-output indices for a location and Pauli type. #[inline] #[must_use] - pub fn logicals(&self, loc_idx: usize, pauli: Pauli) -> &[u32] { + pub fn dem_outputs(&self, loc_idx: usize, pauli: Pauli) -> &[u32] { match pauli { Pauli::I => &[], - Pauli::X => self.logicals_x.row(loc_idx), - Pauli::Y => self.logicals_y.row(loc_idx), - Pauli::Z => self.logicals_z.row(loc_idx), + Pauli::X => self.dem_outputs_x.row(loc_idx), + Pauli::Y => self.dem_outputs_y.row(loc_idx), + Pauli::Z => self.dem_outputs_z.row(loc_idx), } } @@ -411,27 +414,27 @@ impl InfluencesSoA { } } - /// Returns whether the location has any logical flips for the given Pauli. + /// Returns whether the location has any DEM-output flips for the given Pauli. #[inline] #[must_use] - pub fn has_logical_flips(&self, loc_idx: usize, pauli: Pauli) -> bool { + pub fn has_dem_output_flips(&self, loc_idx: usize, pauli: Pauli) -> bool { match pauli { Pauli::I => false, - Pauli::X => !self.logicals_x.row_is_empty(loc_idx), - Pauli::Y => !self.logicals_y.row_is_empty(loc_idx), - Pauli::Z => !self.logicals_z.row_is_empty(loc_idx), + Pauli::X => !self.dem_outputs_x.row_is_empty(loc_idx), + Pauli::Y => !self.dem_outputs_y.row_is_empty(loc_idx), + Pauli::Z => !self.dem_outputs_z.row_is_empty(loc_idx), } } /// Classifies a fault at the given location. /// - /// Returns (`has_syndrome`, `causes_logical_error`). + /// Returns (`has_syndrome`, `flips_dem_output`). #[inline] #[must_use] pub fn classify(&self, loc_idx: usize, pauli: Pauli) -> (bool, bool) { ( self.has_detector_flips(loc_idx, pauli), - self.has_logical_flips(loc_idx, pauli), + self.has_dem_output_flips(loc_idx, pauli), ) } @@ -440,9 +443,9 @@ impl InfluencesSoA { self.detectors_x.finish_row(); self.detectors_y.finish_row(); self.detectors_z.finish_row(); - self.logicals_x.finish_row(); - self.logicals_y.finish_row(); - self.logicals_z.finish_row(); + self.dem_outputs_x.finish_row(); + self.dem_outputs_y.finish_row(); + self.dem_outputs_z.finish_row(); self.num_locations += 1; } @@ -452,17 +455,17 @@ impl InfluencesSoA { let offset_bytes = (self.detectors_x.offsets.len() + self.detectors_y.offsets.len() + self.detectors_z.offsets.len() - + self.logicals_x.offsets.len() - + self.logicals_y.offsets.len() - + self.logicals_z.offsets.len()) + + self.dem_outputs_x.offsets.len() + + self.dem_outputs_y.offsets.len() + + self.dem_outputs_z.offsets.len()) * std::mem::size_of::(); let data_bytes = (self.detectors_x.data.len() + self.detectors_y.data.len() + self.detectors_z.data.len() - + self.logicals_x.data.len() - + self.logicals_y.data.len() - + self.logicals_z.data.len()) + + self.dem_outputs_x.data.len() + + self.dem_outputs_y.data.len() + + self.dem_outputs_z.data.len()) * std::mem::size_of::(); InfluencesSoAStats { @@ -470,23 +473,25 @@ impl InfluencesSoA { total_detector_entries: self.detectors_x.total_elements() + self.detectors_y.total_elements() + self.detectors_z.total_elements(), - total_logical_entries: self.logicals_x.total_elements() - + self.logicals_y.total_elements() - + self.logicals_z.total_elements(), + total_dem_output_entries: self.dem_outputs_x.total_elements() + + self.dem_outputs_y.total_elements() + + self.dem_outputs_z.total_elements(), offset_bytes, data_bytes, total_bytes: offset_bytes + data_bytes, } } - /// Returns the maximum logical index found in the influence map, if any. + /// Returns the maximum raw DEM-output influence index, if any. /// - /// This is useful for determining the number of logical operators tracked. + /// When metadata is present, callers should use [`Self::num_dem_outputs`] + /// for the standard observable `L` namespace and [`Self::num_tracked_ops`] + /// for PECOS tracked operators. #[must_use] - pub fn max_logical_index(&self) -> Option { - let max_x = self.logicals_x.data.iter().max(); - let max_y = self.logicals_y.data.iter().max(); - let max_z = self.logicals_z.data.iter().max(); + pub fn max_dem_output_index(&self) -> Option { + let max_x = self.dem_outputs_x.data.iter().max(); + let max_y = self.dem_outputs_y.data.iter().max(); + let max_z = self.dem_outputs_z.data.iter().max(); [max_x, max_y, max_z] .into_iter() @@ -503,8 +508,8 @@ pub struct InfluencesSoAStats { pub num_locations: usize, /// Total detector entries across all Pauli types. pub total_detector_entries: usize, - /// Total logical entries across all Pauli types. - pub total_logical_entries: usize, + /// Total DEM-output entries across all Pauli types. + pub total_dem_output_entries: usize, /// Bytes used for offset arrays. pub offset_bytes: usize, /// Bytes used for data arrays. @@ -529,7 +534,24 @@ pub struct DagFaultInfluenceMap { pub detectors: Vec, /// All measurements in the circuit (node, qubit, basis). + /// Ordered by MeasId when gates carry MeasId values. pub measurements: Vec<(usize, usize, u8)>, + + /// MeasId IDs for each measurement, in the same order as `measurements`. + /// When populated, `meas_ids[i]` is the stable identity of `measurements[i]`. + /// Empty for legacy circuits without MeasId on gates. + pub meas_ids: Vec, + + /// Optional labels for non-detector DEM outputs. + /// Indices match the DEM-output indices in `influences`. + pub dem_output_labels: Vec>, + + /// Optional metadata for non-detector outputs tracked by backward propagation. + /// + /// These entries are PECOS tracked operators unless explicitly marked as + /// observables by a specialized builder. Standard DEM `L` observables + /// should normally come from measurement-record metadata instead. + pub dem_output_metadata: Vec, } impl DagFaultInfluenceMap { @@ -541,12 +563,15 @@ impl DagFaultInfluenceMap { locations: Vec::with_capacity(num_locations), detectors: Vec::new(), measurements: Vec::new(), + meas_ids: Vec::new(), + dem_output_labels: Vec::new(), + dem_output_metadata: Vec::new(), } } /// Classifies a fault at the given location index. /// - /// Returns (`has_syndrome`, `causes_logical_error`). + /// Returns (`has_syndrome`, `flips_dem_output`). #[inline] #[must_use] pub fn classify_fault(&self, loc_idx: usize, pauli: u8) -> (bool, bool) { @@ -560,11 +585,132 @@ impl DagFaultInfluenceMap { self.influences.detectors(loc_idx, Pauli::from_u8(pauli)) } - /// Returns the logical indices flipped by a fault. + /// Returns all non-detector DEM output indices flipped by a fault. + #[inline] + #[must_use] + pub fn get_dem_output_indices(&self, loc_idx: usize, pauli: u8) -> &[u32] { + self.influences.dem_outputs(loc_idx, Pauli::from_u8(pauli)) + } + + /// Returns the number of standard DEM `L` observable outputs. + #[must_use] + pub fn num_dem_outputs(&self) -> usize { + if self.dem_output_metadata.is_empty() { + return self.influences.max_dem_output_index().map_or(0, |i| i + 1); + } + self.dem_output_metadata + .iter() + .filter(|metadata| metadata.kind == DemOutputKind::Observable) + .count() + } + + /// Returns the number of observables. + #[must_use] + pub fn num_observables(&self) -> usize { + self.num_dem_outputs() + } + + /// Returns the number of PECOS tracked operators. + #[must_use] + pub fn num_tracked_ops(&self) -> usize { + self.dem_output_metadata + .iter() + .filter(|metadata| metadata.kind == DemOutputKind::TrackedOperator) + .count() + } + + /// Returns tracked-Pauli-operator output indices flipped by a fault. + #[must_use] + pub fn get_tracked_op_indices(&self, loc_idx: usize, pauli: u8) -> Vec { + let outputs = self.get_dem_output_indices(loc_idx, pauli); + outputs + .iter() + .filter_map(|&idx| self.tracked_op_id_for_internal_dem_output(idx)) + .collect() + } + + /// Returns observable output indices flipped by a fault. + #[must_use] + pub fn get_observable_indices(&self, loc_idx: usize, pauli: u8) -> Vec { + let outputs = self.get_dem_output_indices(loc_idx, pauli); + if self.dem_output_metadata.is_empty() { + return outputs.to_vec(); + } + outputs + .iter() + .filter_map(|&idx| self.observable_id_for_internal_dem_output(idx)) + .collect() + } + + /// Map an internal non-detector output index to the standard observable + /// `L` ID space. + #[must_use] + pub fn observable_id_for_internal_dem_output(&self, idx: u32) -> Option { + if self.dem_output_metadata.is_empty() { + return Some(idx); + } + self.output_id_for_kind(idx, DemOutputKind::Observable) + } + + /// Map an internal non-detector output index to the PECOS tracked-operator + /// ID space. + #[must_use] + pub fn tracked_op_id_for_internal_dem_output(&self, idx: u32) -> Option { + self.output_id_for_kind(idx, DemOutputKind::TrackedOperator) + } + + /// Returns true if a fault flips any non-detector DEM output. + #[inline] + #[must_use] + pub fn has_dem_output_flips(&self, loc_idx: usize, pauli: u8) -> bool { + !self.get_dem_output_indices(loc_idx, pauli).is_empty() + } + + /// Returns true if a fault flips any tracked Pauli operator. + #[must_use] + pub fn has_tracked_op_flips(&self, loc_idx: usize, pauli: u8) -> bool { + !self.get_tracked_op_indices(loc_idx, pauli).is_empty() + } + + /// Returns true if a fault flips any observable. + #[must_use] + pub fn has_observable_flips(&self, loc_idx: usize, pauli: u8) -> bool { + !self.get_observable_indices(loc_idx, pauli).is_empty() + } + + /// Returns the label for a detector, if any. #[inline] #[must_use] - pub fn get_logical_indices(&self, loc_idx: usize, pauli: u8) -> &[u32] { - self.influences.logicals(loc_idx, Pauli::from_u8(pauli)) + pub fn detector_label(&self, detector_idx: usize) -> Option<&str> { + self.detectors + .get(detector_idx) + .and_then(|d| d.name.as_deref()) + } + + /// Returns the label for a DEM output, if any. + #[inline] + #[must_use] + pub fn dem_output_label(&self, dem_output_idx: usize) -> Option<&str> { + self.dem_output_labels + .get(dem_output_idx) + .and_then(|l| l.as_deref()) + } + + /// Returns metadata for a DEM output, if available. + #[inline] + #[must_use] + pub fn dem_output_metadata(&self, dem_output_idx: usize) -> Option<&DemOutputMetadata> { + self.dem_output_metadata.get(dem_output_idx) + } + + /// Replace this map's backward-propagated non-detector outputs with + /// another map's outputs and metadata. + pub fn merge_dem_outputs_from(&mut self, other: &Self) { + self.influences.dem_outputs_x = other.influences.dem_outputs_x.clone(); + self.influences.dem_outputs_y = other.influences.dem_outputs_y.clone(); + self.influences.dem_outputs_z = other.influences.dem_outputs_z.clone(); + self.dem_output_labels = other.dem_output_labels.clone(); + self.dem_output_metadata = other.dem_output_metadata.clone(); } /// Returns the location at the given index. @@ -589,14 +735,19 @@ impl DagFaultInfluenceMap { /// Export CSR data for GPU use. /// + /// The exported DEM-output arrays contain only standard observable `L` + /// outputs. PECOS tracked operators share the internal backward-propagation + /// storage but are intentionally filtered out here so decoder-oriented GPU + /// code cannot count tracked probes as logical errors. + /// /// Returns all CSR arrays needed to construct a GPU influence sampler: - /// (`num_locations`, `num_detectors`, `num_logicals`, + /// (`num_locations`, `num_detectors`, `num_dem_outputs`, /// `detector_offsets_x`, `detector_data_x`, /// `detector_offsets_y`, `detector_data_y`, /// `detector_offsets_z`, `detector_data_z`, - /// `logical_offsets_x`, `logical_data_x`, - /// `logical_offsets_y`, `logical_data_y`, - /// `logical_offsets_z`, `logical_data_z`) + /// `dem_output_offsets_x`, `dem_output_data_x`, + /// `dem_output_offsets_y`, `dem_output_data_y`, + /// `dem_output_offsets_z`, `dem_output_data_z`) #[allow(clippy::type_complexity)] #[must_use] pub fn export_csr( @@ -622,29 +773,683 @@ impl DagFaultInfluenceMap { let num_locations = self.locations.len() as u32; #[allow(clippy::cast_possible_truncation)] // detector count fits in u32 let num_detectors = self.detectors.len() as u32; - #[allow(clippy::cast_possible_truncation)] // logical index fits in u32 - let num_logicals = self - .influences - .max_logical_index() - .map_or(0, |i| i as u32 + 1); + #[allow(clippy::cast_possible_truncation)] // DEM-output count fits in u32 + let num_dem_outputs = self.num_dem_outputs() as u32; + let (dem_output_offsets_x, dem_output_data_x) = + self.observable_csr(&self.influences.dem_outputs_x); + let (dem_output_offsets_y, dem_output_data_y) = + self.observable_csr(&self.influences.dem_outputs_y); + let (dem_output_offsets_z, dem_output_data_z) = + self.observable_csr(&self.influences.dem_outputs_z); + + ( + num_locations, + num_detectors, + num_dem_outputs, + self.influences.detectors_x.offsets.clone(), + self.influences.detectors_x.data.clone(), + self.influences.detectors_y.offsets.clone(), + self.influences.detectors_y.data.clone(), + self.influences.detectors_z.offsets.clone(), + self.influences.detectors_z.data.clone(), + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, + ) + } + + fn observable_csr(&self, csr: &CsrArray) -> (Vec, Vec) { + if self.dem_output_metadata.is_empty() { + return (csr.offsets.clone(), csr.data.clone()); + } + + let mut offsets = Vec::with_capacity(csr.offsets.len()); + let mut data = Vec::new(); + offsets.push(0); + for row_idx in 0..csr.num_rows() { + data.extend( + csr.row(row_idx) + .iter() + .filter_map(|&idx| self.observable_id_for_internal_dem_output(idx)), + ); + #[allow(clippy::cast_possible_truncation)] // CSR data length fits in u32 + offsets.push(data.len() as u32); + } + (offsets, data) + } + + fn output_id_for_kind(&self, idx: u32, kind: DemOutputKind) -> Option { + let metadata = self.dem_output_metadata.get(idx as usize)?; + if metadata.kind != kind { + return None; + } + #[allow(clippy::cast_possible_truncation)] // filtered output count fits in u32 + Some( + self.dem_output_metadata[..idx as usize] + .iter() + .filter(|metadata| metadata.kind == kind) + .count() as u32, + ) + } +} + +/// Role of a non-detector DEM output under backward Pauli propagation. +#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] +pub enum DemOutputKind { + /// An observable DEM output. + Observable, + /// A tracked operator annotation with no observable readout. + TrackedOperator, +} + +impl DemOutputKind { + /// Stable string used by PECOS metadata JSON. + #[must_use] + pub const fn as_str(self) -> &'static str { + match self { + Self::Observable => "observable", + Self::TrackedOperator => "tracked_operator", + } + } + + /// Parses a stable PECOS metadata string. + #[must_use] + pub fn from_metadata_str(kind: &str) -> Option { + match kind { + "observable" => Some(Self::Observable), + "tracked_operator" => Some(Self::TrackedOperator), + _ => None, + } + } +} + +/// Metadata for a PECOS non-detector DEM output. +/// +/// Stim-compatible DEM strings only have `L` markers. PECOS keeps this +/// richer record alongside the DEM so callers can tell whether a marker came +/// from an observable or from a tracked Pauli operator annotation. +#[derive(Debug, Clone, PartialEq, Eq)] +pub struct DemOutputMetadata { + /// The output role. + pub kind: DemOutputKind, + /// Pauli string whose flip is tracked. + pub pauli: PauliString, + /// Optional user label. + pub label: Option, +} + +impl DemOutputMetadata { + /// Creates DEM output metadata. + #[must_use] + pub fn new(kind: DemOutputKind, mut pauli: PauliString, label: Option) -> Self { + // A tracked Pauli op flip is an anticommutation property; global phase has + // no meaning for DEM/sampler output. + pauli.set_phase(QuarterPhase::PlusOne); + Self { kind, pauli, label } + } + + /// Creates metadata for a tracked operator. + #[must_use] + pub fn tracked_operator(pauli: PauliString) -> Self { + Self::new(DemOutputKind::TrackedOperator, pauli, None) + } + + /// Creates metadata for an observable. + #[must_use] + pub fn observable(pauli: PauliString) -> Self { + Self::new(DemOutputKind::Observable, pauli, None) + } + + /// Sets a user-facing op label. + #[must_use] + pub fn with_label(mut self, label: impl Into) -> Self { + self.label = Some(label.into()); + self + } + + /// Sets an optional user-facing op label. + #[must_use] + pub fn with_optional_label(mut self, label: Option) -> Self { + self.label = label; + self + } +} + +// ============================================================================ +// Fault Introspection +// ============================================================================ + +/// A per-gate fault location with access to all possible fault events. +/// +/// Each gate at a specific timing (before/after) is one fault location. +/// Multi-qubit gates have multiple per-qubit sub-locations whose effects +/// compose via XOR (symmetric difference) for multi-qubit Pauli events. +/// +/// Borrows the influence map so you can query events directly: +/// ```ignore +/// for loc in map.gate_fault_locations() { +/// for event in loc.events() { ... } +/// } +/// ``` +pub struct GateFaultLocation<'a> { + map: &'a DagFaultInfluenceMap, + /// DAG node index. + pub node: usize, + /// Gate type. + pub gate_type: GateType, + /// Qubits this gate acts on. + pub qubits: Vec, + /// Before (true) or after (false) the gate. + pub before: bool, + /// Per-qubit location indices in the influence map. + qubit_loc_indices: Vec<(usize, usize)>, // (qubit, loc_idx) +} + +/// The effect of a specific fault event (multi-qubit Pauli error). +#[derive(Debug, Clone)] +pub struct FaultEffect { + /// The multi-qubit Pauli error. + pub pauli: pecos_core::PauliString, + /// Detector indices that flip. + pub detectors: Vec, + /// DEM-output indices that flip. + pub dem_outputs: Vec, + /// Raw measurements that flip: `(node, qubit, basis)`. + /// + /// Derived from the flipped detectors. Each auto-detected detector + /// corresponds to one or more measurements; this expands them. + pub measurements: Vec<(usize, usize, u8)>, +} + +impl FaultEffect { + /// Compose two fault effects (as if both faults occurred). + /// + /// - Paulis are multiplied (handles same-qubit algebra + tensor product) + /// - Detectors/dem_outputs/measurements are XOR'd (symmetric difference) + /// + /// This is the building block for weight-w fault analysis: + /// ```ignore + /// let w2 = effect_a.compose(&effect_b); + /// let w3 = w2.compose(&effect_c); + /// ``` + #[must_use] + pub fn compose(&self, other: &Self) -> Self { + let mut pauli = self.pauli.clone() * other.pauli.clone(); + pauli.set_phase(pecos_core::QuarterPhase::PlusOne); + + let mut detectors = self.detectors.clone(); + xor_sorted(&mut detectors, &other.detectors); + + let mut dem_outputs = self.dem_outputs.clone(); + xor_sorted(&mut dem_outputs, &other.dem_outputs); + + let mut measurements = self.measurements.clone(); + xor_sorted_tuples(&mut measurements, &other.measurements); + + Self { + pauli, + detectors, + dem_outputs, + measurements, + } + } +} + +impl GateFaultLocation<'_> { + /// Number of qubits this gate acts on. + #[must_use] + pub fn num_qubits(&self) -> usize { + self.qubits.len() + } + + /// All possible fault events at this location. + /// + /// Only returns multi-qubit Paulis where at least one qubit's + /// single-qubit component has a non-trivial effect in the influence + /// map. E.g., a measurement-before location might only yield X + /// faults since Z before MZ is invisible. + #[must_use] + pub fn possible_faults(&self) -> Vec { + let active = self.active_paulis_per_qubit(); + if active.is_empty() { + return Vec::new(); + } + + let mut combos: Vec> = vec![vec![]]; + for &(q, ref paulis) in &active { + let mut next = Vec::new(); + for existing in &combos { + next.push(existing.clone()); + for &p in paulis { + let mut extended = existing.clone(); + extended.push((q.index(), p)); + next.push(extended); + } + } + combos = next; + } + + combos + .into_iter() + .filter(|c| !c.is_empty()) + .map(|entries| { + pecos_core::PauliString::with_phase_and_paulis( + pecos_core::QuarterPhase::PlusOne, + entries + .iter() + .map(|&(q, p)| (p, QubitId::from(q))) + .collect(), + ) + }) + .collect() + } + + /// All fault events that have non-trivial effects (flip at least one + /// detector or logical). + #[must_use] + pub fn events(&self) -> Vec { + self.possible_faults() + .into_iter() + .map(|ps| self.query(&ps)) + .filter(|e| !e.detectors.is_empty() || !e.dem_outputs.is_empty()) + .collect() + } + + /// All physically possible fault events, including those with no effect. + /// + /// Use this for probability-correct enumeration (e.g., ML decoder). + /// Events with empty detectors and dem_outputs are "trivial" faults that + /// happen with real probability but don't change any observable. + #[must_use] + pub fn all_events(&self) -> Vec { + self.all_physical_paulis() + .into_iter() + .map(|ps| self.query(&ps)) + .collect() + } + + /// All physically meaningful single-qubit Paulis per qubit, regardless + /// of whether they have non-trivial effects in the influence map. + /// + /// Gate-type filtering applies (PZ/MZ only X/Y) but effect filtering + /// does not. This ensures correct probability accounting. + fn all_physical_paulis(&self) -> Vec { + let physical: &[pecos_core::Pauli] = match self.gate_type { + // Z-basis prep/measurement: only X (bit-flip) fault. + GateType::PZ | GateType::QAlloc | GateType::MZ | GateType::MeasureFree => { + &[pecos_core::Pauli::X] + } + // Unitary gates: all single-qubit Paulis. + _ => &[ + pecos_core::Pauli::X, + pecos_core::Pauli::Y, + pecos_core::Pauli::Z, + ], + }; + + // Build all combinations (including I on each qubit) + let mut combos: Vec> = vec![vec![]]; + for &q in &self.qubits { + let mut next = Vec::new(); + for existing in &combos { + next.push(existing.clone()); // I on this qubit + for &p in physical { + let mut extended = existing.clone(); + extended.push((q.index(), p)); + next.push(extended); + } + } + combos = next; + } + + combos + .into_iter() + .filter(|c| !c.is_empty()) + .map(|entries| { + pecos_core::PauliString::with_phase_and_paulis( + pecos_core::QuarterPhase::PlusOne, + entries + .iter() + .map(|&(q, p)| (p, QubitId::from(q))) + .collect(), + ) + }) + .collect() + } + + /// Query the effect of a specific multi-qubit Pauli event. + #[must_use] + pub fn query(&self, pauli: &pecos_core::PauliString) -> FaultEffect { + let entries: Vec<(usize, pecos_core::Pauli)> = pauli + .paulis() + .iter() + .map(|&(p, q)| (q.index(), p)) + .collect(); + let (detectors, dem_outputs) = self.compose_effects(&entries); + + // Resolve detector indices to raw measurements + let measurements = self.resolve_measurements(&detectors); + + FaultEffect { + pauli: pauli.clone(), + detectors, + dem_outputs, + measurements, + } + } + + /// Which single-qubit Paulis are physically meaningful at each qubit. + /// + /// Filters based on both the influence map (has non-trivial effect) and + /// the gate type (Z after PZ is unphysical, Z before MZ is invisible). + fn active_paulis_per_qubit(&self) -> Vec<(QubitId, Vec)> { + // Determine which Paulis are physical for this gate type + let physical_paulis: &[Pauli] = match self.gate_type { + // Z-basis prep/measurement: only X (bit-flip) fault. + GateType::PZ | GateType::QAlloc | GateType::MZ | GateType::MeasureFree => &[Pauli::X], + // Unitary gates: all single-qubit Paulis. + _ => &[Pauli::X, Pauli::Y, Pauli::Z], + }; + + self.qubit_loc_indices + .iter() + .filter_map(|&(qubit, loc_idx)| { + let mut paulis = Vec::new(); + for &p in physical_paulis { + if self.map.influences.has_detector_flips(loc_idx, p) + || self.map.influences.has_dem_output_flips(loc_idx, p) + { + paulis.push(propagator_to_core_pauli(p)); + } + } + if paulis.is_empty() { + None + } else { + Some((QubitId::from(qubit), paulis)) + } + }) + .collect() + } + + /// Compose per-qubit effects via XOR (symmetric difference). + fn compose_effects(&self, entries: &[(usize, pecos_core::Pauli)]) -> (Vec, Vec) { + let mut det_set: Vec = Vec::new(); + let mut dem_output_set: Vec = Vec::new(); + + for &(qubit, pauli) in entries { + if pauli == pecos_core::Pauli::I { + continue; + } + let prop_pauli = core_to_propagator_pauli(pauli); + + if let Some(&(_, loc_idx)) = self.qubit_loc_indices.iter().find(|&&(q, _)| q == qubit) { + let dets = self.map.influences.detectors(loc_idx, prop_pauli); + xor_sorted(&mut det_set, dets); + let dem_outputs = self.map.influences.dem_outputs(loc_idx, prop_pauli); + xor_sorted(&mut dem_output_set, dem_outputs); + } + } + + (det_set, dem_output_set) + } + + /// Resolve detector indices to raw measurement tuples. + fn resolve_measurements(&self, detector_indices: &[u32]) -> Vec<(usize, usize, u8)> { + let mut measurements = Vec::new(); + for &det_idx in detector_indices { + if let Some(det) = self.map.detectors.get(det_idx as usize) { + for meas_id in &det.measurements { + measurements.push((meas_id.tick, meas_id.qubit, meas_id.basis)); + } + } + } + measurements + } +} + +/// Symmetric difference for sorted `(usize, usize, u8)` tuples (measurements). +fn xor_sorted_tuples(acc: &mut Vec<(usize, usize, u8)>, other: &[(usize, usize, u8)]) { + if other.is_empty() { + return; + } + if acc.is_empty() { + acc.extend_from_slice(other); + return; + } + let mut result = Vec::with_capacity(acc.len() + other.len()); + let mut i = 0; + let mut j = 0; + while i < acc.len() && j < other.len() { + match acc[i].cmp(&other[j]) { + std::cmp::Ordering::Less => { + result.push(acc[i]); + i += 1; + } + std::cmp::Ordering::Greater => { + result.push(other[j]); + j += 1; + } + std::cmp::Ordering::Equal => { + i += 1; + j += 1; + } + } + } + result.extend_from_slice(&acc[i..]); + result.extend_from_slice(&other[j..]); + *acc = result; +} + +/// Convert `pecos_core::Pauli` to the propagator's `Pauli`. +fn core_to_propagator_pauli(p: pecos_core::Pauli) -> Pauli { + match p { + pecos_core::Pauli::I => Pauli::I, + pecos_core::Pauli::X => Pauli::X, + pecos_core::Pauli::Y => Pauli::Y, + pecos_core::Pauli::Z => Pauli::Z, + } +} + +/// Convert the propagator's `Pauli` to `pecos_core::Pauli`. +fn propagator_to_core_pauli(p: Pauli) -> pecos_core::Pauli { + match p { + Pauli::I => pecos_core::Pauli::I, + Pauli::X => pecos_core::Pauli::X, + Pauli::Y => pecos_core::Pauli::Y, + Pauli::Z => pecos_core::Pauli::Z, + } +} + +/// Symmetric difference of two sorted u32 slices, mutating `acc` in place. +fn xor_sorted(acc: &mut Vec, other: &[u32]) { + if other.is_empty() { + return; + } + if acc.is_empty() { + acc.extend_from_slice(other); + return; + } + // Build symmetric difference: elements in exactly one of the two sets + let mut result = Vec::with_capacity(acc.len() + other.len()); + let mut i = 0; + let mut j = 0; + while i < acc.len() && j < other.len() { + match acc[i].cmp(&other[j]) { + std::cmp::Ordering::Less => { + result.push(acc[i]); + i += 1; + } + std::cmp::Ordering::Greater => { + result.push(other[j]); + j += 1; + } + std::cmp::Ordering::Equal => { + // In both sets -- they cancel (XOR) + i += 1; + j += 1; + } + } + } + result.extend_from_slice(&acc[i..]); + result.extend_from_slice(&other[j..]); + *acc = result; +} + +impl DagFaultInfluenceMap { + /// Group per-qubit locations into per-gate fault locations. + /// + /// Each returned [`GateFaultLocation`] represents a gate at a specific + /// timing (before/after) and supports querying multi-qubit Pauli events. + /// + /// ```ignore + /// for loc in map.gate_fault_locations() { + /// for event in loc.events() { + /// println!("{}: dets={:?} dem_outputs={:?}", event.pauli, event.detectors, event.dem_outputs); + /// } + /// } + /// ``` + #[must_use] + pub fn gate_fault_locations(&self) -> Vec> { + let mut groups: std::collections::BTreeMap<(usize, bool), Vec<(usize, usize)>> = + std::collections::BTreeMap::new(); + + for (loc_idx, loc) in self.locations.iter().enumerate() { + let key = (loc.node, loc.before); + for q in &loc.qubits { + groups.entry(key).or_default().push((q.index(), loc_idx)); + } + } + + groups + .into_iter() + .map(|((node, before), qubit_locs)| { + let gate_type = self.locations[qubit_locs[0].1].gate_type; + let qubits: Vec = + qubit_locs.iter().map(|&(q, _)| QubitId::from(q)).collect(); + GateFaultLocation { + map: self, + node, + gate_type, + qubits, + before, + qubit_loc_indices: qubit_locs, + } + }) + .collect() + } +} + +// ============================================================================ +// Weight-w Fault Enumeration +// ============================================================================ + +/// A single component of a multi-fault combination. +#[derive(Debug, Clone)] +pub struct FaultComponent { + /// Index into `gate_fault_locations()`. + pub location_index: usize, + /// The fault event at this location. + pub event: FaultEffect, +} + +/// A weight-w combination of faults and their combined effect. +#[derive(Debug, Clone)] +pub struct FaultCombo { + /// The individual (location, event) pairs. + pub components: Vec, + /// Combined effect (XOR of all component effects). + pub effect: FaultEffect, +} + +impl DagFaultInfluenceMap { + /// Enumerate all weight-w fault combinations, calling `f` for each. + /// + /// At weight 1, this iterates every fault location and every possible + /// fault event. At weight 2, all pairs of (location, event). And so on. + /// + /// Uses a callback to avoid allocating a potentially huge result vec. + /// + /// ```ignore + /// // Find all undetectable weight-2 errors + /// map.for_each_fault_combo(2, |combo| { + /// if !combo.effect.dem_outputs.is_empty() && combo.effect.detectors.is_empty() { + /// println!("Undetectable w=2:"); + /// for c in &combo.components { + /// println!(" {} at loc {}", c.event.pauli, c.location_index); + /// } + /// } + /// }); + /// ``` + pub fn for_each_fault_combo(&self, weight: usize, mut f: impl FnMut(&FaultCombo)) { + let locs = self.gate_fault_locations(); + + // Pre-compute events for each location + let all_events: Vec> = + locs.iter().map(GateFaultLocation::events).collect(); + + let empty_effect = FaultEffect { + pauli: pecos_core::PauliString::identity(), + detectors: Vec::new(), + dem_outputs: Vec::new(), + measurements: Vec::new(), + }; + + let mut components = Vec::with_capacity(weight); + let mut effects_stack = vec![empty_effect]; + + enumerate_combos( + &all_events, + weight, + 0, // start_loc + &mut components, + &mut effects_stack, + &mut f, + ); + } +} - ( - num_locations, - num_detectors, - num_logicals, - self.influences.detectors_x.offsets.clone(), - self.influences.detectors_x.data.clone(), - self.influences.detectors_y.offsets.clone(), - self.influences.detectors_y.data.clone(), - self.influences.detectors_z.offsets.clone(), - self.influences.detectors_z.data.clone(), - self.influences.logicals_x.offsets.clone(), - self.influences.logicals_x.data.clone(), - self.influences.logicals_y.offsets.clone(), - self.influences.logicals_y.data.clone(), - self.influences.logicals_z.offsets.clone(), - self.influences.logicals_z.data.clone(), - ) +/// Recursive helper for weight-w combination enumeration. +fn enumerate_combos( + all_events: &[Vec], + remaining: usize, + start_loc: usize, + components: &mut Vec, + effects_stack: &mut Vec, + f: &mut impl FnMut(&FaultCombo), +) { + if remaining == 0 { + f(&FaultCombo { + components: components.clone(), + effect: effects_stack.last().unwrap().clone(), + }); + return; + } + + for loc_idx in start_loc..all_events.len() { + for event in &all_events[loc_idx] { + let combined = effects_stack.last().unwrap().compose(event); + + components.push(FaultComponent { + location_index: loc_idx, + event: event.clone(), + }); + effects_stack.push(combined); + + enumerate_combos( + all_events, + remaining - 1, + loc_idx + 1, // no repeats + components, + effects_stack, + f, + ); + + components.pop(); + effects_stack.pop(); + } } } @@ -779,8 +1584,8 @@ impl InfluenceRecorder for BucketRecorder { if obs_x { self.z_buckets[loc_idx].push(det); } - // Y fault anticommutes with X or Z observable - if obs_x || obs_z { + // Y fault anticommutes with X or Z but NOT both (Y commutes with Y) + if obs_x ^ obs_z { self.y_buckets[loc_idx].push(det); } } @@ -873,28 +1678,26 @@ impl<'a> DagFaultAnalyzer<'a> { for &node in &topo_order { if let Some(gate) = propagator.gate(node) { + // Skip meta-gates — they don't create fault locations + if gate.gate_type.is_meta() { + continue; + } + let is_measurement = matches!(gate.gate_type, GateType::MZ | GateType::MeasureFree); - let is_prep = matches!(gate.gate_type, GateType::PZ | GateType::QAlloc); // Convert QubitId to usize let qubits: SmallVec<[usize; 2]> = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); - // Create per-qubit fault locations for proper depolarizing noise analysis + // Standard circuit noise model: one fault location per gate. + // Measurement: before (X flip before readout) + // All others (prep, unitary, idle): after + // Idle gates on non-active qubits provide the missing "before" + // coverage that would otherwise require before-gate locations. + let before = is_measurement; for &q in &qubits { let single_qubit: SmallVec<[usize; 2]> = smallvec::smallvec![q]; - - if is_measurement { - // Measurements only have before=true locations - locations.push(node, single_qubit, true, gate.gate_type); - } else if is_prep { - // Preps only have before=false locations - locations.push(node, single_qubit, false, gate.gate_type); - } else { - // Regular gates have both before and after locations - locations.push(node, single_qubit.clone(), true, gate.gate_type); - locations.push(node, single_qubit, false, gate.gate_type); - } + locations.push(node, single_qubit, before, gate.gate_type); } } } @@ -934,8 +1737,9 @@ impl<'a> DagFaultAnalyzer<'a> { map.locations = self.locations.to_dag_spacetime_locations(); // Extract measurements and create detectors - let measurements = self.extract_measurements(); + let (measurements, meas_ids) = self.extract_measurements(); map.measurements.clone_from(&measurements); + map.meas_ids = meas_ids; for &(node, qubit, basis) in &measurements { let measurement_id = MeasurementId { @@ -946,11 +1750,8 @@ impl<'a> DagFaultAnalyzer<'a> { map.detectors.push(DetectorId::single(measurement_id)); } - // Use bucket recorder for O(n) construction - let mut recorder = BucketRecorder::new(num_locations); - - // Propagate using the generic method with bucket recorder - self.propagate_all(&mut recorder); + // Use forest propagation: per-ancilla Phase 1/Phase 2 split. + let recorder = self.propagate_all_forest(); // Convert buckets to SoA format (O(n) flattening) map.influences = recorder.into_soa(); @@ -968,8 +1769,13 @@ impl<'a> DagFaultAnalyzer<'a> { /// measurements on lower-indexed qubits appear first when they're in the /// same "layer" of the circuit. #[must_use] - pub fn extract_measurements(&self) -> Vec<(usize, usize, u8)> { - let mut measurements = Vec::new(); + /// Extract measurements with optional MeasId IDs. + /// + /// Returns `(measurements, meas_ids)` where: + /// - `measurements` is `Vec<(node, qubit, basis)>` in MeasId order + /// - `meas_ids` is `Vec` (empty for legacy circuits) + pub fn extract_measurements(&self) -> (Vec<(usize, usize, u8)>, Vec) { + let mut entries = Vec::new(); // (sort_key, qubit, node, basis, Option) for &node in self.propagator.topo_order() { if let Some(gate) = self.propagator.gate(node) { @@ -978,23 +1784,39 @@ impl<'a> DagFaultAnalyzer<'a> { _ => continue, }; - let topo_pos = self.propagator.topo_position(node); - for qubit in &gate.qubits { - // Store (topo_pos, qubit, node, basis) for sorting - measurements.push((topo_pos, qubit.index(), node, basis)); + if !gate.meas_ids.is_empty() { + for (i, qubit) in gate.qubits.iter().enumerate() { + let mr = gate.meas_ids.get(i).copied(); + let sort_key = mr.map(|m| m.index()).unwrap_or(usize::MAX); + entries.push((sort_key, qubit.index(), node, basis, mr)); + } + } else { + let topo_pos = self.propagator.topo_position(node); + for qubit in &gate.qubits { + entries.push((topo_pos, qubit.index(), node, basis, None)); + } } } } - // Sort by (topological_position, qubit_index) for deterministic ordering - // This ensures measurements on lower-indexed qubits come first when concurrent - measurements.sort_by_key(|&(topo_pos, qubit, _, _)| (topo_pos, qubit)); + entries.sort_by_key(|&(sort_key, qubit, _, _, _)| (sort_key, qubit)); - // Return in the expected format: (node, qubit, basis) - measurements + let has_meas_ids = entries.iter().any(|(_, _, _, _, mr)| mr.is_some()); + let meas_ids = if has_meas_ids { + entries + .iter() + .map(|(_, _, _, _, mr)| mr.unwrap_or(pecos_core::MeasId(usize::MAX))) + .collect() + } else { + Vec::new() + }; + + let measurements = entries .into_iter() - .map(|(_, qubit, node, basis)| (node, qubit, basis)) - .collect() + .map(|(_, qubit, node, basis, _)| (node, qubit, basis)) + .collect(); + + (measurements, meas_ids) } // ========================================================================= @@ -1152,6 +1974,317 @@ impl<'a> DagFaultAnalyzer<'a> { } } + // ==================================================================== + // Forest propagation: per-ancilla Phase 1 / Phase 2 split + // ==================================================================== + + /// Captured influence entry from Phase 2 (shared tail below PZ). + /// Stored with `topo_pos` for prefix slicing across measurements. + + /// Phase 1: propagate from MZ backward through within-round gates, + /// stopping at the ancilla's PZ. Records influences normally. + /// Returns the PZ node's topo position, or None if no PZ was hit. + /// + /// After return, `work.heap` still contains data qubit gates below + /// the PZ — ready for Phase 2. + fn propagate_phase1( + &self, + meas_node: usize, + meas_qubit: usize, + basis: u8, + detector_idx: usize, + recorder: &mut R, + work: &mut PropagationBuffers, + prop: &mut PauliProp, + ) -> Option { + let visited = &mut work.visited; + let active_qubits = &mut work.active_qubits; + let heap = &mut work.heap; + visited.fill(false); + active_qubits.fill(false); + heap.clear(); + + *prop = PauliProp::new(); + if basis == 0 { + prop.track_z(&[meas_qubit]); + } else { + prop.track_x(&[meas_qubit]); + } + + let meas_topo_pos = self.propagator.topo_position(meas_node); + self.record_at_node_generic(meas_node, prop, detector_idx, recorder, true); + + if meas_qubit <= self.max_qubit() { + active_qubits[meas_qubit] = true; + for (topo_pos, node) in self.propagator.qubit_gates_backward(meas_qubit) { + if topo_pos < meas_topo_pos && !visited[node] { + visited[node] = true; + heap.push((topo_pos, node)); + } + } + } + + while let Some((_, node)) = heap.pop() { + if let Some(gate) = self.propagator.gate(node) { + let mut was_active = [false; 8]; + for (j, q) in gate.qubits.iter().enumerate() { + if j < was_active.len() && q.index() <= self.max_qubit() { + was_active[j] = active_qubits[q.index()]; + } + } + + self.record_at_node_generic(node, prop, detector_idx, recorder, false); + + if matches!(gate.gate_type, GateType::PZ | GateType::QAlloc) { + let pz_topo = self.propagator.topo_position(node); + for q in &gate.qubits { + let idx = q.index(); + if idx <= self.max_qubit() { + if prop.contains_x(idx) { + prop.track_x(&[idx]); + } + if prop.contains_z(idx) { + prop.track_z(&[idx]); + } + active_qubits[idx] = false; + } + } + // Stop Phase 1 — data qubit gates remain in the heap. + return Some(pz_topo); + } + + apply_gate(prop, gate, Direction::Backward); + self.record_at_node_generic(node, prop, detector_idx, recorder, true); + + let node_topo_pos = self.propagator.topo_position(node); + for (j, q) in gate.qubits.iter().enumerate() { + let idx = q.index(); + if idx <= self.max_qubit() { + let now_active = prop.contains_x(idx) || prop.contains_z(idx); + let was = j < was_active.len() && was_active[j]; + if now_active && !was { + active_qubits[idx] = true; + for (topo_pos, new_node) in self.propagator.qubit_gates_backward(idx) { + if topo_pos < node_topo_pos && !visited[new_node] { + visited[new_node] = true; + heap.push((topo_pos, new_node)); + } + } + } else if !now_active && was { + active_qubits[idx] = false; + } + } + } + } + } + None // No PZ hit (e.g., first round init detectors) + } + + /// Phase 2: continue backward propagation from data qubit frontier + /// below PZ. Records to `recorder` AND captures the visited node + /// sequence for replay. + fn propagate_phase2_capture( + &self, + detector_idx: usize, + recorder: &mut R, + work: &mut PropagationBuffers, + prop: &mut PauliProp, + ) -> Vec { + let mut visited_nodes: Vec = Vec::new(); + let visited = &mut work.visited; + let active_qubits = &mut work.active_qubits; + let heap = &mut work.heap; + + while let Some((_, node)) = heap.pop() { + if let Some(gate) = self.propagator.gate(node) { + let mut was_active = [false; 8]; + for (j, q) in gate.qubits.iter().enumerate() { + if j < was_active.len() && q.index() <= self.max_qubit() { + was_active[j] = active_qubits[q.index()]; + } + } + + self.record_at_node_generic(node, prop, detector_idx, recorder, false); + visited_nodes.push(node); + + if matches!(gate.gate_type, GateType::PZ | GateType::QAlloc) { + for q in &gate.qubits { + let idx = q.index(); + if idx <= self.max_qubit() { + if prop.contains_x(idx) { + prop.track_x(&[idx]); + } + if prop.contains_z(idx) { + prop.track_z(&[idx]); + } + active_qubits[idx] = false; + } + } + continue; + } + + apply_gate(prop, gate, Direction::Backward); + self.record_at_node_generic(node, prop, detector_idx, recorder, true); + + let node_topo = self.propagator.topo_position(node); + for (j, q) in gate.qubits.iter().enumerate() { + let idx = q.index(); + if idx <= self.max_qubit() { + let now_active = prop.contains_x(idx) || prop.contains_z(idx); + let was = j < was_active.len() && was_active[j]; + if now_active && !was { + active_qubits[idx] = true; + for (topo_pos, new_node) in self.propagator.qubit_gates_backward(idx) { + if topo_pos < node_topo && !visited[new_node] { + visited[new_node] = true; + heap.push((topo_pos, new_node)); + } + } + } else if !now_active && was { + active_qubits[idx] = false; + } + } + } + } + } + visited_nodes + } + + /// Replay Phase 2 using a cached node sequence. + /// + /// Iterates the captured nodes, re-applies gates backward to the Pauli + /// state, and re-records with the correct `obs_x/obs_z` values. No heap + /// or visited array needed — just a flat loop over known nodes. + fn replay_phase2( + &self, + nodes: &[usize], + pz_topo: usize, + detector_idx: usize, + recorder: &mut R, + prop: &mut PauliProp, + ) { + for &node in nodes { + if self.propagator.topo_position(node) >= pz_topo { + continue; + } + + if let Some(gate) = self.propagator.gate(node) { + self.record_at_node_generic(node, prop, detector_idx, recorder, false); + + if matches!(gate.gate_type, GateType::PZ | GateType::QAlloc) { + for q in &gate.qubits { + let idx = q.index(); + if idx <= self.max_qubit() { + if prop.contains_x(idx) { + prop.track_x(&[idx]); + } + if prop.contains_z(idx) { + prop.track_z(&[idx]); + } + } + } + continue; + } + + apply_gate(prop, gate, Direction::Backward); + self.record_at_node_generic(node, prop, detector_idx, recorder, true); + } + } + } + + /// Parallel forest propagation: groups measurements by ancilla qubit, + /// propagates the latest measurement fully with capture, replays the + /// shared tail prefix for earlier measurements. + #[must_use] + pub fn propagate_all_forest(&self) -> BucketRecorder { + use rayon::prelude::*; + + let (measurements, _meas_ids) = self.extract_measurements(); + let num_locations = self.locations.len(); + + // Group measurement indices by qubit (ancilla). + let mut by_qubit: BTreeMap> = BTreeMap::new(); + for (det_idx, &(_, qubit, _)) in measurements.iter().enumerate() { + by_qubit.entry(qubit).or_default().push(det_idx); + } + + // Collect ancilla groups for parallel iteration. + let groups: Vec> = by_qubit.into_values().collect(); + + let per_thread: Vec = groups + .par_iter() + .map(|det_indices| { + let mut recorder = BucketRecorder::new(num_locations); + let mut work = PropagationBuffers { + visited: vec![false; self.propagator.max_node() + 1], + active_qubits: vec![false; self.propagator.max_qubit() + 1], + heap: BinaryHeap::with_capacity(64), + }; + + // Sort by topo position (ascending = earliest first). + let mut sorted = det_indices.clone(); + sorted.sort_by_key(|&i| self.propagator.topo_position(measurements[i].0)); + + // Latest measurement: Phase 1 + Phase 2 with capture + let latest = *sorted.last().unwrap(); + let (l_node, l_qubit, l_basis) = measurements[latest]; + + let mut prop = PauliProp::new(); + + let _pz_topo = self.propagate_phase1( + l_node, + l_qubit, + l_basis, + latest, + &mut recorder, + &mut work, + &mut prop, + ); + let tail_capture = + self.propagate_phase2_capture(latest, &mut recorder, &mut work, &mut prop); + + // Earlier measurements: Phase 1 + replay tail with correct Pauli state + for &det_idx in sorted[..sorted.len() - 1].iter().rev() { + let (m_node, m_qubit, m_basis) = measurements[det_idx]; + + let pz_topo_i = self.propagate_phase1( + m_node, + m_qubit, + m_basis, + det_idx, + &mut recorder, + &mut work, + &mut prop, + ); + + // Replay cached node sequence with correct Pauli state + if let Some(pz_pos) = pz_topo_i { + self.replay_phase2( + &tail_capture, + pz_pos, + det_idx, + &mut recorder, + &mut prop, + ); + } + } + + recorder + }) + .collect(); + + // Merge all recorders + let mut merged = BucketRecorder::new(num_locations); + for rec in per_thread { + for i in 0..num_locations { + merged.x_buckets[i].extend(rec.x_buckets[i].iter().copied()); + merged.y_buckets[i].extend(rec.y_buckets[i].iter().copied()); + merged.z_buckets[i].extend(rec.z_buckets[i].iter().copied()); + } + } + merged + } + /// Builds a fault influence map using a custom recorder. /// /// This is the most flexible method, allowing custom recording strategies. @@ -1176,7 +2309,7 @@ impl<'a> DagFaultAnalyzer<'a> { /// println!("Total influences: {}", recorder.count); /// ``` pub fn propagate_all(&self, recorder: &mut R) { - let measurements = self.extract_measurements(); + let (measurements, _) = self.extract_measurements(); let mut work = PropagationBuffers { visited: vec![false; self.propagator.max_node() + 1], @@ -1195,6 +2328,55 @@ impl<'a> DagFaultAnalyzer<'a> { ); } } + + /// Parallel version: propagates from all measurements using rayon. + /// Each thread gets its own `BucketRecorder`, results are merged. + #[must_use] + pub fn propagate_all_parallel(&self) -> BucketRecorder { + use rayon::prelude::*; + + let (measurements, _) = self.extract_measurements(); + let num_locations = self.locations.len(); + + let chunk_size = measurements.len().div_ceil(rayon::current_num_threads()); + + let per_thread: Vec = measurements + .par_chunks(chunk_size.max(1)) + .enumerate() + .map(|(chunk_idx, chunk)| { + let base_idx = chunk_idx * chunk_size; + let mut recorder = BucketRecorder::new(num_locations); + let mut work = PropagationBuffers { + visited: vec![false; self.propagator.max_node() + 1], + active_qubits: vec![false; self.propagator.max_qubit() + 1], + heap: BinaryHeap::with_capacity(64), + }; + + for (i, &(node, qubit, basis)) in chunk.iter().enumerate() { + self.propagate_from_measurement_generic( + node, + qubit, + basis, + base_idx + i, + &mut recorder, + &mut work, + ); + } + recorder + }) + .collect(); + + // Merge all recorders + let mut merged = BucketRecorder::new(num_locations); + for rec in per_thread { + for i in 0..num_locations { + merged.x_buckets[i].extend(rec.x_buckets[i].iter().copied()); + merged.y_buckets[i].extend(rec.y_buckets[i].iter().copied()); + merged.z_buckets[i].extend(rec.z_buckets[i].iter().copied()); + } + } + merged + } } #[cfg(test)] @@ -1370,12 +2552,14 @@ mod tests { qubits: vec![QubitId::from(0)], before: true, gate_type: GateType::H, + idle_duration: 0, }; let loc2 = DagSpacetimeLocation { node: 1, qubits: vec![QubitId::from(0)], before: true, gate_type: GateType::H, + idle_duration: 0, }; assert!(loc1 < loc2); } @@ -1414,9 +2598,9 @@ mod tests { soa.detectors_y.finish_row(); soa.detectors_z.finish_row(); soa.detectors_x.finish_row(); - soa.logicals_x.finish_row(); - soa.logicals_y.finish_row(); - soa.logicals_z.finish_row(); + soa.dem_outputs_x.finish_row(); + soa.dem_outputs_y.finish_row(); + soa.dem_outputs_z.finish_row(); soa.num_locations += 1; // Location 1: Z flips detector 1 @@ -1424,9 +2608,9 @@ mod tests { soa.detectors_y.finish_row(); soa.detectors_z.push(1); soa.detectors_z.finish_row(); - soa.logicals_x.finish_row(); - soa.logicals_y.finish_row(); - soa.logicals_z.finish_row(); + soa.dem_outputs_x.finish_row(); + soa.dem_outputs_y.finish_row(); + soa.dem_outputs_z.finish_row(); soa.num_locations += 1; assert!(soa.has_detector_flips(0, Pauli::X)); @@ -1435,6 +2619,103 @@ mod tests { assert!(soa.has_detector_flips(1, Pauli::Z)); } + #[test] + fn test_export_csr_filters_tracked_operators_from_dem_outputs() { + let mut dag = DagCircuit::new(); + dag.pz(&[0]); + dag.h(&[0]); + + let map = crate::fault_tolerance::InfluenceBuilder::new(&dag) + .with_z(&[0]) + .build(); + + assert_eq!(map.num_dem_outputs(), 0); + assert_eq!(map.num_tracked_ops(), 1); + assert!( + map.influences.max_dem_output_index().is_some(), + "tracked operator should still use internal propagation storage" + ); + + let ( + _num_locations, + _num_detectors, + num_dem_outputs, + _detector_offsets_x, + _detector_data_x, + _detector_offsets_y, + _detector_data_y, + _detector_offsets_z, + _detector_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, + ) = map.export_csr(); + + assert_eq!(num_dem_outputs, 0); + assert!(dem_output_data_x.is_empty()); + assert!(dem_output_data_y.is_empty()); + assert!(dem_output_data_z.is_empty()); + assert_eq!(dem_output_offsets_x.len(), map.locations.len() + 1); + assert_eq!(dem_output_offsets_y.len(), map.locations.len() + 1); + assert_eq!(dem_output_offsets_z.len(), map.locations.len() + 1); + } + + #[test] + fn test_dem_output_helpers_use_separate_compact_id_spaces() { + let mut map = DagFaultInfluenceMap::with_capacity(1); + map.locations.push(DagSpacetimeLocation { + node: 0, + qubits: vec![QubitId(0)], + before: false, + gate_type: GateType::H, + idle_duration: 0, + }); + map.dem_output_metadata = vec![ + DemOutputMetadata::tracked_operator(pecos_core::PauliString::xs(&[0])), + DemOutputMetadata::observable(pecos_core::PauliString::zs(&[0])), + DemOutputMetadata::tracked_operator(pecos_core::PauliString::zs(&[1])), + ]; + + map.influences.dem_outputs_x.extend([0, 1, 2]); + map.influences.dem_outputs_x.finish_row(); + map.influences.dem_outputs_y.finish_row(); + map.influences.dem_outputs_z.finish_row(); + map.influences.detectors_x.finish_row(); + map.influences.detectors_y.finish_row(); + map.influences.detectors_z.finish_row(); + map.influences.num_locations = 1; + + assert_eq!(map.num_dem_outputs(), 1); + assert_eq!(map.num_tracked_ops(), 2); + assert_eq!(map.get_observable_indices(0, Pauli::X.as_u8()), vec![0]); + assert_eq!(map.get_tracked_op_indices(0, Pauli::X.as_u8()), vec![0, 1]); + + let ( + _num_locations, + _num_detectors, + num_dem_outputs, + _detector_offsets_x, + _detector_data_x, + _detector_offsets_y, + _detector_data_y, + _detector_offsets_z, + _detector_data_z, + dem_output_offsets_x, + dem_output_data_x, + _dem_output_offsets_y, + _dem_output_data_y, + _dem_output_offsets_z, + _dem_output_data_z, + ) = map.export_csr(); + + assert_eq!(num_dem_outputs, 1); + assert_eq!(dem_output_offsets_x, vec![0, 1]); + assert_eq!(dem_output_data_x, vec![0]); + } + // ========================================================================= // Per-Qubit Fault Location Tests // ========================================================================= @@ -1460,11 +2741,11 @@ mod tests { .filter(|loc| matches!(loc.gate_type, GateType::CX)) .collect(); - // Should have 4 locations: before/after for each of 2 qubits + // Should have 2 locations: one per qubit (after only) assert_eq!( cx_locations.len(), - 4, - "CX should have 4 fault locations (before/after x 2 qubits)" + 2, + "CX should have 2 fault locations (1 per qubit, after gate)" ); // Each location should have exactly 1 qubit (per-qubit fault model) @@ -1509,31 +2790,31 @@ mod tests { #[test] fn test_per_qubit_fault_influences() { - // Test that per-qubit fault locations correctly track influences + // Test that per-qubit fault locations correctly track influences. + // In the standard model, faults are AFTER unitary gates. + // X on the TARGET after CX(0, 2) flips the Z-measurement on qubit 2. let mut dag = DagCircuit::new(); dag.pz(&[2]); // ancilla - dag.cx(&[(0, 2)]); // X on control spreads to target + dag.cx(&[(0, 2)]); // X on target flips measurement dag.mz(&[2]); let analyzer = DagFaultAnalyzer::new(&dag); let map = analyzer.build_influence_map(); - // X error on data qubit 0 (control of CX) should flip the Z-measurement - // because X on control stays on control, but also spreads to target - let mut found_data_qubit_influence = false; + // X error on target qubit 2 after CX should flip the measurement + let mut found_target_influence = false; for (loc_idx, loc) in map.locations.iter().enumerate() { - // Check data qubit 0 locations - if loc.qubits.iter().any(|q| q.index() == 0) { - // X fault (pauli=1) should have detector flips - if map.influences.has_detector_flips(loc_idx, Pauli::X) { - found_data_qubit_influence = true; - } + if loc.qubits.iter().any(|q| q.index() == 2) + && matches!(loc.gate_type, GateType::CX) + && map.influences.has_detector_flips(loc_idx, Pauli::X) + { + found_target_influence = true; } } assert!( - found_data_qubit_influence, - "X error on data qubit should influence measurement" + found_target_influence, + "X error on target qubit after CX should influence measurement" ); } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/pauli.rs b/crates/pecos-qec/src/fault_tolerance/propagator/pauli.rs index c60079e7a..eabeff99e 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/pauli.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/pauli.rs @@ -17,6 +17,7 @@ use super::PauliFault; use pecos_core::gate_type::GateType; +use pecos_core::{half_turn_decomposition, try_simplify_r1xy, try_simplify_rotation}; use pecos_quantum::TickCircuit; use pecos_simulators::{CliffordGateable, PauliProp}; @@ -49,10 +50,49 @@ pub enum Direction { /// - **Measure gates**: No transformation in either direction (for propagation purposes) #[inline] pub fn apply_gate(prop: &mut PauliProp, gate: &pecos_core::Gate, direction: Direction) { - // Use gate.qubits directly - SmallVec derefs to &[QubitId], no allocation needed - let qubits = &gate.qubits; + if apply_named_gate(prop, gate.gate_type, &gate.qubits, direction) { + return; + } match gate.gate_type { + GateType::RZ + | GateType::RX + | GateType::RY + | GateType::RZZ + | GateType::RXX + | GateType::RYY => { + if let Some(&angle) = gate.angles.first() { + if let Some(clifford) = try_simplify_rotation(gate.gate_type, angle) { + let _ = apply_named_gate(prop, clifford, &gate.qubits, direction); + return; + } + + if let Some(pauli) = half_turn_decomposition(gate.gate_type, angle) { + for &qubit in &gate.qubits { + let _ = apply_named_gate(prop, pauli, &[qubit], direction); + } + } + } + } + GateType::R1XY if gate.angles.len() >= 2 => { + let theta = gate.angles[0]; + let phi = gate.angles[1]; + if let Some(clifford) = try_simplify_r1xy(theta, phi) { + let _ = apply_named_gate(prop, clifford, &gate.qubits, direction); + } + } + _ => {} + } +} + +#[inline] +fn apply_named_gate( + prop: &mut PauliProp, + gate_type: GateType, + qubits: &[pecos_core::QubitId], + direction: Direction, +) -> bool { + match gate_type { // Self-adjoint single-qubit gates - same in both directions GateType::I => { prop.identity(qubits); @@ -69,8 +109,20 @@ pub fn apply_gate(prop: &mut PauliProp, gate: &pecos_core::Gate, direction: Dire GateType::H => { prop.h(qubits); } + GateType::F => { + match direction { + Direction::Forward => prop.f(qubits), + Direction::Backward => prop.fdg(qubits), + }; + } + GateType::Fdg => { + match direction { + Direction::Forward => prop.fdg(qubits), + Direction::Backward => prop.f(qubits), + }; + } - // Non-self-adjoint gates - swap with adjoint for backward + // Non-self-adjoint single-qubit gates - swap with adjoint for backward GateType::SX => { match direction { Direction::Forward => prop.sx(qubits), @@ -110,30 +162,92 @@ pub fn apply_gate(prop: &mut PauliProp, gate: &pecos_core::Gate, direction: Dire // Self-adjoint two-qubit gates - same in both directions GateType::CX => { + let pairs: Vec<_> = qubits + .chunks(2) + .filter(|c| c.len() == 2) + .map(|c| (c[0], c[1])) + .collect(); + prop.cx(&pairs); + } + GateType::CY => { + let pairs: Vec<_> = qubits + .chunks(2) + .filter(|c| c.len() == 2) + .map(|c| (c[0], c[1])) + .collect(); + prop.cy(&pairs); + } + GateType::CZ => { + let pairs: Vec<_> = qubits + .chunks(2) + .filter(|c| c.len() == 2) + .map(|c| (c[0], c[1])) + .collect(); + prop.cz(&pairs); + } + GateType::SWAP => { + let pairs: Vec<_> = qubits + .chunks(2) + .filter(|c| c.len() == 2) + .map(|c| (c[0], c[1])) + .collect(); + prop.swap(&pairs); + } + + // Non-self-adjoint two-qubit Clifford gates - swap with adjoint for backward + GateType::SXX => { if qubits.len() >= 2 { - prop.cx(&[(qubits[0], qubits[1])]); + match direction { + Direction::Forward => prop.sxx(&[(qubits[0], qubits[1])]), + Direction::Backward => prop.sxxdg(&[(qubits[0], qubits[1])]), + }; } } - GateType::CY => { + GateType::SXXdg => { if qubits.len() >= 2 { - prop.cy(&[(qubits[0], qubits[1])]); + match direction { + Direction::Forward => prop.sxxdg(&[(qubits[0], qubits[1])]), + Direction::Backward => prop.sxx(&[(qubits[0], qubits[1])]), + }; } } - GateType::CZ => { + GateType::SYY => { if qubits.len() >= 2 { - prop.cz(&[(qubits[0], qubits[1])]); + match direction { + Direction::Forward => prop.syy(&[(qubits[0], qubits[1])]), + Direction::Backward => prop.syydg(&[(qubits[0], qubits[1])]), + }; } } - GateType::SWAP => { + GateType::SYYdg => { + if qubits.len() >= 2 { + match direction { + Direction::Forward => prop.syydg(&[(qubits[0], qubits[1])]), + Direction::Backward => prop.syy(&[(qubits[0], qubits[1])]), + }; + } + } + GateType::SZZ => { if qubits.len() >= 2 { - prop.swap(&[(qubits[0], qubits[1])]); + match direction { + Direction::Forward => prop.szz(&[(qubits[0], qubits[1])]), + Direction::Backward => prop.szzdg(&[(qubits[0], qubits[1])]), + }; + } + } + GateType::SZZdg => { + if qubits.len() >= 2 { + match direction { + Direction::Forward => prop.szzdg(&[(qubits[0], qubits[1])]), + Direction::Backward => prop.szz(&[(qubits[0], qubits[1])]), + }; } } - // No-op: Prep, QAlloc, Measure, MeasureFree, and other unsupported gate types - // don't transform Paulis for propagation purposes - _ => {} + _ => return false, } + + true } /// Propagates a `PauliProp` through a circuit in the specified direction. diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs b/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs index 747e4653a..6bd895238 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs @@ -18,8 +18,8 @@ //! For better performance, consider using [`DagFaultAnalyzer`](super::DagFaultAnalyzer) //! with DAG circuits, which provides 5-50x speedup through sparse traversal. -use super::types::{DetectorId, FaultInfluence, FaultInfluenceMap, LogicalId, MeasurementId}; -use super::{SpacetimeLocation, extract_spacetime_locations}; +use super::types::{DetectorId, FaultInfluence, FaultInfluenceMap, MeasurementId, TrackedOpId}; +use super::{Direction, SpacetimeLocation, apply_gate, extract_spacetime_locations}; use pecos_core::gate_type::GateType; use pecos_quantum::TickCircuit; use pecos_simulators::PauliProp; @@ -85,20 +85,20 @@ impl<'a> TickFaultAnalyzer<'a> { /// creates a lookup table for fault classification. #[must_use] pub fn build_influence_map(&self) -> FaultInfluenceMap { - self.build_influence_map_with_logicals(&[]) + self.build_influence_map_with_tracked_ops(&[]) } - /// Builds the fault influence map with logical operator tracking. + /// Builds the fault influence map with tracked Pauli operator tracking. /// /// # Arguments /// - /// * `logicals` - Logical operators as (`x_positions`, `z_positions`) pairs. + /// * `tracked_ops` - Tracked Pauli operators as (`x_positions`, `z_positions`) pairs. /// The first element of each pair is the X component positions, /// the second is the Z component positions. #[must_use] - pub fn build_influence_map_with_logicals( + pub fn build_influence_map_with_tracked_ops( &self, - logicals: &[(&[usize], &[usize])], + tracked_ops: &[(&[usize], &[usize])], ) -> FaultInfluenceMap { let mut map = FaultInfluenceMap::new(); @@ -112,11 +112,11 @@ impl<'a> TickFaultAnalyzer<'a> { map.detectors.push(DetectorId::single(*m)); } - // Create logical IDs - for (i, _) in logicals.iter().enumerate() { - map.logicals.push(LogicalId { - logical_qubit: i, - observable: 0, // Z observable + // Create tracked-operator IDs + for (i, _) in tracked_ops.iter().enumerate() { + map.tracked_ops.push(TrackedOpId { + op_index: i, + component: 0, }); } @@ -131,13 +131,13 @@ impl<'a> TickFaultAnalyzer<'a> { self.propagate_from_measurement(measurement, &mut map); } - // Backward propagate from each logical operator - for (i, (x_pos, z_pos)) in logicals.iter().enumerate() { - let logical_id = LogicalId { - logical_qubit: i, - observable: 0, + // Backward propagate from each tracked Pauli operator + for (i, (x_pos, z_pos)) in tracked_ops.iter().enumerate() { + let tracked_op_id = TrackedOpId { + op_index: i, + component: 0, }; - self.propagate_from_logical(x_pos, z_pos, &logical_id, &mut map); + self.propagate_from_tracked_op(x_pos, z_pos, &tracked_op_id, &mut map); } // Build reverse maps @@ -259,37 +259,37 @@ impl<'a> TickFaultAnalyzer<'a> { } } - /// Propagates backward from a logical operator. + /// Propagates backward from a tracked Pauli operator. /// - /// We propagate the logical OBSERVABLE backward through the circuit. - /// An error P at location L flips the logical if P anticommutes with - /// the back-propagated observable at L. + /// We propagate the tracked operator backward through the circuit. An error + /// P at location L flips it if P anticommutes with the back-propagated + /// operator at L. /// /// This uses sparse traversal: only gates touching qubits with non-trivial /// Paulis are processed, providing significant speedup for circuits with /// local connectivity. - fn propagate_from_logical( + fn propagate_from_tracked_op( &self, x_positions: &[usize], z_positions: &[usize], - logical_id: &LogicalId, + tracked_op_id: &TrackedOpId, map: &mut FaultInfluenceMap, ) { - // Start with the logical observable itself (not swapped) + // Start with the tracked operator itself (not swapped) // The recording function handles anticommutation checking let mut prop = PauliProp::new(); // Track active qubits for sparse traversal let mut active_qubits = vec![false; self.max_qubit + 1]; - // X positions in logical -> X in prop + // X positions in tracked op -> X in prop for &q in x_positions { prop.track_x(&[q]); if q <= self.max_qubit { active_qubits[q] = true; } } - // Z positions in logical -> Z in prop + // Z positions in tracked op -> Z in prop for &q in z_positions { prop.track_z(&[q]); if q <= self.max_qubit { @@ -312,7 +312,7 @@ impl<'a> TickFaultAnalyzer<'a> { tick_idx, &prop, &dummy_detector, - Some(logical_id), + Some(tracked_op_id), map, false, ); @@ -345,7 +345,7 @@ impl<'a> TickFaultAnalyzer<'a> { tick_idx, &prop, &dummy_detector, - Some(logical_id), + Some(tracked_op_id), map, true, ); @@ -368,7 +368,7 @@ impl<'a> TickFaultAnalyzer<'a> { tick_idx: usize, prop: &PauliProp, detector: &DetectorId, - logical: Option<&LogicalId>, + tracked_op: Option<&TrackedOpId>, map: &mut FaultInfluenceMap, only_before: bool, ) { @@ -400,8 +400,8 @@ impl<'a> TickFaultAnalyzer<'a> { // X fault anticommutes with Z or Y observable let x_flips = obs_z; // Z or Y (both have Z component) if x_flips { - if let Some(log) = logical { - influence.logical_flips[1].push(*log); + if let Some(op) = tracked_op { + influence.tracked_op_flips[1].push(*op); } else { influence.detector_flips[1].push(detector.clone()); influence.measurement_flips[1] @@ -419,8 +419,8 @@ impl<'a> TickFaultAnalyzer<'a> { // (Z anticommutes with X, Z anticommutes with Y=iXZ) let z_flips = obs_x; // X or Y (both have X component) if z_flips { - if let Some(log) = logical { - influence.logical_flips[3].push(*log); + if let Some(op) = tracked_op { + influence.tracked_op_flips[3].push(*op); } else { influence.detector_flips[3].push(detector.clone()); influence.measurement_flips[3] @@ -434,12 +434,11 @@ impl<'a> TickFaultAnalyzer<'a> { } } - // Y fault = iXZ: Y anticommutes with X, Z, and Y - // Y anticommutes with observable if observable has X or Z component - let y_flips = obs_x || obs_z; + // Y fault: Y anticommutes with X or Z but NOT both (Y commutes with Y) + let y_flips = obs_x ^ obs_z; if y_flips { - if let Some(log) = logical { - influence.logical_flips[2].push(*log); + if let Some(op) = tracked_op { + influence.tracked_op_flips[2].push(*op); } else { influence.detector_flips[2].push(detector.clone()); influence.measurement_flips[2] @@ -465,132 +464,28 @@ impl<'a> TickFaultAnalyzer<'a> { /// - SZ (S gate): X → -Y, Y → X, Z → Z (adjoint of forward) #[inline] fn apply_gate_backward(prop: &mut PauliProp, gate: &pecos_core::Gate) { - // Access gate.qubits directly - no allocation needed let qubits = &gate.qubits; - match gate.gate_type { - GateType::CX => { - // CX is self-adjoint, same propagation as forward - // X on control -> X on control AND target - // X on target -> X on target - // Z on control -> Z on control - // Z on target -> Z on control AND target - if qubits.len() >= 2 { - let control = qubits[0].index(); - let target = qubits[1].index(); - - let ctrl_x = prop.contains_x(control); - let tgt_z = prop.contains_z(target); - - // X spreads from control to target - if ctrl_x { - prop.track_x(&[target]); - } - // Z spreads from target to control - if tgt_z { - prop.track_z(&[control]); - } - } - } - - GateType::CZ => { - // CZ is self-adjoint - // X on either qubit -> X on that qubit AND Z on the other - if qubits.len() >= 2 { - let q0 = qubits[0].index(); - let q1 = qubits[1].index(); - - let x0 = prop.contains_x(q0); - let x1 = prop.contains_x(q1); - - if x0 { - prop.track_z(&[q1]); - } - if x1 { - prop.track_z(&[q0]); - } - } - } - - GateType::H => { - // H is self-adjoint: X <-> Z - if let Some(qid) = qubits.first() { - let q = qid.index(); - let has_x = prop.contains_x(q); - let has_z = prop.contains_z(q); - - // Swap X and Z using toggle - if has_x && !has_z { - // Remove X by toggling, add Z - prop.track_x(&[q]); // toggles off - prop.track_z(&[q]); - } else if has_z && !has_x { - // Remove Z by toggling, add X - prop.track_z(&[q]); // toggles off - prop.track_x(&[q]); - } - // If both or neither, no change needed - } - } - - GateType::SZ => { - // SZ† (adjoint): X -> -Y (we track as XZ), Y -> X, Z -> Z - // Since we track Paulis mod phase, X -> Y means X -> XZ - if let Some(qid) = qubits.first() { - let q = qid.index(); - let has_x = prop.contains_x(q); - let has_z = prop.contains_z(q); - - if has_x && !has_z { - // X -> XZ (Y with phase) - prop.track_z(&[q]); - } else if has_x && has_z { - // Y (XZ) -> X: remove Z by toggling - prop.track_z(&[q]); // toggles off - } - // Z -> Z (no change) + if matches!(gate.gate_type, GateType::PZ | GateType::QAlloc) { + // Preparation resets the qubit - backward propagation stops here + // Any Pauli on a prepared qubit doesn't propagate further back + // Toggle off both X and Z if present + for qid in qubits { + let q = qid.index(); + if prop.contains_x(q) { + prop.track_x(&[q]); // toggles off } - } - - GateType::SZdg => { - // SZdg = SZ†, so SZdg† = SZ - // Forward SZ: X -> Y, Y -> -X, Z -> Z - if let Some(qid) = qubits.first() { - let q = qid.index(); - let has_x = prop.contains_x(q); - let has_z = prop.contains_z(q); - - if has_x && !has_z { - // X -> XZ (Y) - prop.track_z(&[q]); - } else if has_x && has_z { - // Y -> X: remove Z by toggling - prop.track_z(&[q]); // toggles off - } + if prop.contains_z(q) { + prop.track_z(&[q]); // toggles off } } - - GateType::PZ | GateType::QAlloc => { - // Preparation resets the qubit - backward propagation stops here - // Any Pauli on a prepared qubit doesn't propagate further back - // Toggle off both X and Z if present - for qid in qubits { - let q = qid.index(); - if prop.contains_x(q) { - prop.track_x(&[q]); // toggles off - } - if prop.contains_z(q) { - prop.track_z(&[q]); // toggles off - } - } - } - - // Pauli gates (X,Y,Z), Measure, MeasureFree, and other gates - no Pauli frame change - _ => {} + return; } + + apply_gate(prop, gate, Direction::Backward); } - /// Builds reverse maps (detector -> faults, logical -> faults). + /// Builds reverse maps (detector -> faults, tracked operator -> faults). fn build_reverse_maps(map: &mut FaultInfluenceMap) { for (loc, influence) in &map.influences { for (pauli, detectors) in influence.detector_flips.iter().enumerate() { @@ -604,12 +499,12 @@ impl<'a> TickFaultAnalyzer<'a> { } } - for (pauli, logicals) in influence.logical_flips.iter().enumerate() { + for (pauli, tracked_ops) in influence.tracked_op_flips.iter().enumerate() { #[allow(clippy::cast_possible_truncation)] // Pauli index 0..2 let pauli_u8 = pauli as u8; - for logical in logicals { - map.logical_to_faults - .entry(*logical) + for tracked_op in tracked_ops { + map.tracked_op_to_faults + .entry(*tracked_op) .or_default() .push((loc.clone(), pauli_u8)); } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/tick_soa.rs b/crates/pecos-qec/src/fault_tolerance/propagator/tick_soa.rs index 74f4d6a2f..3ab747afc 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/tick_soa.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/tick_soa.rs @@ -12,10 +12,10 @@ //! 5. **Direct array access**: Skips Option-returning methods in hot loops use super::SpacetimeLocation; -use super::types::{DetectorId, FaultInfluence, FaultInfluenceMap, LogicalId, MeasurementId}; -use pecos_core::gate_type::GateType; +use super::types::{DetectorId, FaultInfluence, FaultInfluenceMap, MeasurementId, TrackedOpId}; +use pecos_core::{QubitId, gate_type::GateType}; use pecos_quantum::tick_circuit_soa::TickCircuitSoA; -use pecos_simulators::PauliProp; +use pecos_simulators::{CliffordGateable, PauliProp}; // ============================================================================ // Work Buffers for Reuse @@ -145,14 +145,14 @@ impl<'a> TickFaultAnalyzerSoA<'a> { /// Builds the complete fault influence map. #[must_use] pub fn build_influence_map(&self) -> FaultInfluenceMap { - self.build_influence_map_with_logicals(&[]) + self.build_influence_map_with_tracked_ops(&[]) } - /// Builds the fault influence map with logical operator tracking. + /// Builds the fault influence map with tracked Pauli operator tracking. #[must_use] - pub fn build_influence_map_with_logicals( + pub fn build_influence_map_with_tracked_ops( &self, - logicals: &[(&[usize], &[usize])], + tracked_ops: &[(&[usize], &[usize])], ) -> FaultInfluenceMap { let mut map = FaultInfluenceMap::new(); @@ -165,11 +165,11 @@ impl<'a> TickFaultAnalyzerSoA<'a> { map.detectors.push(DetectorId::single(*m)); } - // Create logical IDs - for (i, _) in logicals.iter().enumerate() { - map.logicals.push(LogicalId { - logical_qubit: i, - observable: 0, + // Create tracked-operator IDs + for (i, _) in tracked_ops.iter().enumerate() { + map.tracked_ops.push(TrackedOpId { + op_index: i, + component: 0, }); } @@ -189,16 +189,16 @@ impl<'a> TickFaultAnalyzerSoA<'a> { self.propagate_from_measurement_optimized(measurement, &mut map, &mut buffers); } - // Backward propagate from each logical operator - for (i, (x_pos, z_pos)) in logicals.iter().enumerate() { - let logical_id = LogicalId { - logical_qubit: i, - observable: 0, + // Backward propagate from each tracked Pauli operator + for (i, (x_pos, z_pos)) in tracked_ops.iter().enumerate() { + let tracked_op_id = TrackedOpId { + op_index: i, + component: 0, }; - self.propagate_from_logical_optimized( + self.propagate_from_tracked_op_optimized( x_pos, z_pos, - &logical_id, + &tracked_op_id, &mut map, &mut buffers, ); @@ -347,45 +347,85 @@ impl<'a> TickFaultAnalyzerSoA<'a> { let qubits = storage.qubits_unchecked(idx); match gate_type { - GateType::CX => { - if qubits.len() >= 2 { - let control = qubits[0].index(); - let target = qubits[1].index(); + GateType::CX if qubits.len() >= 2 => { + let control = qubits[0].index(); + let target = qubits[1].index(); - let ctrl_x = prop.contains_x(control); - let tgt_z = prop.contains_z(target); + let ctrl_x = prop.contains_x(control); + let tgt_z = prop.contains_z(target); - if ctrl_x { - prop.track_x(&[target]); - } - if tgt_z { - prop.track_z(&[control]); - } - - // Update active qubits - Self::update_active_qubit(control, prop, buffers); - Self::update_active_qubit(target, prop, buffers); + if ctrl_x { + prop.track_x(&[target]); + } + if tgt_z { + prop.track_z(&[control]); } + + // Update active qubits + Self::update_active_qubit(control, prop, buffers); + Self::update_active_qubit(target, prop, buffers); } - GateType::CZ => { - if qubits.len() >= 2 { - let q0 = qubits[0].index(); - let q1 = qubits[1].index(); + GateType::CZ if qubits.len() >= 2 => { + let q0 = qubits[0].index(); + let q1 = qubits[1].index(); + + let x0 = prop.contains_x(q0); + let x1 = prop.contains_x(q1); + + if x0 { + prop.track_z(&[q1]); + } + if x1 { + prop.track_z(&[q0]); + } - let x0 = prop.contains_x(q0); - let x1 = prop.contains_x(q1); + Self::update_active_qubit(q0, prop, buffers); + Self::update_active_qubit(q1, prop, buffers); + } - if x0 { - prop.track_z(&[q1]); + GateType::CY + | GateType::SWAP + | GateType::SXX + | GateType::SXXdg + | GateType::SYY + | GateType::SYYdg + | GateType::SZZ + | GateType::SZZdg + if qubits.len() >= 2 => + { + let q0 = qubits[0]; + let q1 = qubits[1]; + let pair = [(q0, q1)]; + match gate_type { + GateType::CY => { + prop.cy(&pair); } - if x1 { - prop.track_z(&[q0]); + GateType::SWAP => { + prop.swap(&pair); } - - Self::update_active_qubit(q0, prop, buffers); - Self::update_active_qubit(q1, prop, buffers); + GateType::SXX => { + prop.sxxdg(&pair); + } + GateType::SXXdg => { + prop.sxx(&pair); + } + GateType::SYY => { + prop.syydg(&pair); + } + GateType::SYYdg => { + prop.syy(&pair); + } + GateType::SZZ => { + prop.szzdg(&pair); + } + GateType::SZZdg => { + prop.szz(&pair); + } + _ => unreachable!(), } + Self::update_active_qubit(q0.index(), prop, buffers); + Self::update_active_qubit(q1.index(), prop, buffers); } GateType::H => { @@ -406,6 +446,39 @@ impl<'a> TickFaultAnalyzerSoA<'a> { } } + GateType::SX + | GateType::SXdg + | GateType::SY + | GateType::SYdg + | GateType::F + | GateType::Fdg => { + if let Some(qid) = qubits.first() { + let q = [QubitId(qid.index())]; + match gate_type { + GateType::SX => { + prop.sxdg(&q); + } + GateType::SXdg => { + prop.sx(&q); + } + GateType::SY => { + prop.sydg(&q); + } + GateType::SYdg => { + prop.sy(&q); + } + GateType::F => { + prop.fdg(&q); + } + GateType::Fdg => { + prop.f(&q); + } + _ => unreachable!(), + } + Self::update_active_qubit(qid.index(), prop, buffers); + } + } + GateType::SZ | GateType::SZdg => { if let Some(qid) = qubits.first() { let q = qid.index(); @@ -448,12 +521,12 @@ impl<'a> TickFaultAnalyzerSoA<'a> { } } - /// Optimized backward propagation from a logical operator. - fn propagate_from_logical_optimized( + /// Optimized backward propagation from a tracked Pauli operator. + fn propagate_from_tracked_op_optimized( &self, x_positions: &[usize], z_positions: &[usize], - logical_id: &LogicalId, + tracked_op_id: &TrackedOpId, map: &mut FaultInfluenceMap, buffers: &mut AnalyzerWorkBuffers, ) { @@ -486,7 +559,7 @@ impl<'a> TickFaultAnalyzerSoA<'a> { tick_idx, &prop, &dummy_detector, - Some(logical_id), + Some(tracked_op_id), map, false, ); @@ -497,7 +570,7 @@ impl<'a> TickFaultAnalyzerSoA<'a> { tick_idx, &prop, &dummy_detector, - Some(logical_id), + Some(tracked_op_id), map, true, ); @@ -511,7 +584,7 @@ impl<'a> TickFaultAnalyzerSoA<'a> { tick_idx: usize, prop: &PauliProp, detector: &DetectorId, - logical: Option<&LogicalId>, + tracked_op: Option<&TrackedOpId>, map: &mut FaultInfluenceMap, only_before: bool, ) { @@ -535,8 +608,8 @@ impl<'a> TickFaultAnalyzerSoA<'a> { if let Some(influence) = map.influences.get_mut(loc) { // X fault anticommutes with Z or Y observable if obs_z { - if let Some(log) = logical { - influence.logical_flips[1].push(*log); + if let Some(op) = tracked_op { + influence.tracked_op_flips[1].push(*op); } else { influence.detector_flips[1].push(detector.clone()); influence.measurement_flips[1] @@ -551,8 +624,8 @@ impl<'a> TickFaultAnalyzerSoA<'a> { // Z fault anticommutes with X or Y observable if obs_x { - if let Some(log) = logical { - influence.logical_flips[3].push(*log); + if let Some(op) = tracked_op { + influence.tracked_op_flips[3].push(*op); } else { influence.detector_flips[3].push(detector.clone()); influence.measurement_flips[3] @@ -565,10 +638,10 @@ impl<'a> TickFaultAnalyzerSoA<'a> { } } - // Y fault anticommutes with any non-identity observable - if obs_x || obs_z { - if let Some(log) = logical { - influence.logical_flips[2].push(*log); + // Y fault: anticommutes with X or Z but NOT both (Y commutes with Y) + if obs_x ^ obs_z { + if let Some(op) = tracked_op { + influence.tracked_op_flips[2].push(*op); } else { influence.detector_flips[2].push(detector.clone()); influence.measurement_flips[2] @@ -599,12 +672,12 @@ impl<'a> TickFaultAnalyzerSoA<'a> { } } - for (pauli, logicals) in influence.logical_flips.iter().enumerate() { + for (pauli, tracked_ops) in influence.tracked_op_flips.iter().enumerate() { #[allow(clippy::cast_possible_truncation)] // Pauli index 0..2 let pauli_u8 = pauli as u8; - for logical in logicals { - map.logical_to_faults - .entry(*logical) + for tracked_op in tracked_ops { + map.tracked_op_to_faults + .entry(*tracked_op) .or_default() .push((loc.clone(), pauli_u8)); } @@ -667,7 +740,7 @@ mod tests { } #[test] - fn test_logical_propagation() { + fn test_tracked_op_propagation() { let mut builder = TickCircuitSoABuilder::new(); builder .tick() @@ -682,9 +755,9 @@ mod tests { let circuit = builder.build(); let analyzer = TickFaultAnalyzerSoA::new(&circuit); - let logicals = [(&[] as &[usize], &[1usize] as &[usize])]; - let map = analyzer.build_influence_map_with_logicals(&logicals); + let tracked_ops = [(&[] as &[usize], &[1usize] as &[usize])]; + let map = analyzer.build_influence_map_with_tracked_ops(&tracked_ops); - assert_eq!(map.logicals.len(), 1); + assert_eq!(map.tracked_ops.len(), 1); } } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/types.rs b/crates/pecos-qec/src/fault_tolerance/propagator/types.rs index 0998d49b1..fd01ffe6c 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/types.rs @@ -149,12 +149,56 @@ impl From for usize { } } -/// A logical observable index. +/// A standard DEM observable `L` output index. #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)] #[repr(transparent)] -pub struct LogicalIdx(pub u32); +pub struct DemOutputIdx(pub u32); -impl LogicalIdx { +/// A PECOS tracked-operator metadata index. +/// +/// This is intentionally separate from [`DemOutputIdx`]: tracked operators are +/// not standard DEM `L` targets and should not be handed to decoders as +/// logical observables. +#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)] +#[repr(transparent)] +pub struct TrackedOpIdx(pub u32); + +impl DemOutputIdx { + #[inline] + #[must_use] + pub const fn new(index: u32) -> Self { + Self(index) + } + + #[inline] + #[must_use] + pub const fn index(self) -> usize { + self.0 as usize + } + + #[inline] + #[must_use] + #[allow(clippy::cast_possible_truncation)] // DEM output index fits in u32 + pub const fn from_usize(index: usize) -> Self { + Self(index as u32) + } +} + +impl From for DemOutputIdx { + #[inline] + fn from(index: usize) -> Self { + Self::from_usize(index) + } +} + +impl From for usize { + #[inline] + fn from(id: DemOutputIdx) -> Self { + id.index() + } +} + +impl TrackedOpIdx { #[inline] #[must_use] pub const fn new(index: u32) -> Self { @@ -169,22 +213,22 @@ impl LogicalIdx { #[inline] #[must_use] - #[allow(clippy::cast_possible_truncation)] // logical index fits in u32 + #[allow(clippy::cast_possible_truncation)] // tracked-op index fits in u32 pub const fn from_usize(index: usize) -> Self { Self(index as u32) } } -impl From for LogicalIdx { +impl From for TrackedOpIdx { #[inline] fn from(index: usize) -> Self { Self::from_usize(index) } } -impl From for usize { +impl From for usize { #[inline] - fn from(id: LogicalIdx) -> Self { + fn from(id: TrackedOpIdx) -> Self { id.index() } } @@ -287,13 +331,13 @@ impl DetectorId { } } -/// Unique identifier for a logical observable. +/// Unique identifier for a tracked Pauli operator in the older tick influence map. #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] -pub struct LogicalId { - /// Index of the logical qubit. - pub logical_qubit: usize, - /// Which observable: 0 = Z, 1 = X. - pub observable: u8, +pub struct TrackedOpId { + /// Index of the tracked operator. + pub op_index: usize, + /// Optional Pauli component marker for callers that split X/Z components. + pub component: u8, } /// What a single fault location influences. @@ -305,8 +349,8 @@ pub struct FaultInfluence { /// Index 0 is unused (identity fault has no effect). pub detector_flips: [Vec; 4], - /// Which logical observables this fault flips, indexed by Pauli type. - pub logical_flips: [Vec; 4], + /// Which tracked Pauli operators this fault flips, indexed by Pauli type. + pub tracked_op_flips: [Vec; 4], /// Which raw measurements this fault flips, indexed by Pauli type. pub measurement_flips: [Vec; 4], @@ -321,7 +365,7 @@ impl FaultInfluence { #[must_use] pub fn is_trivial(&self) -> bool { self.detector_flips.iter().all(std::vec::Vec::is_empty) - && self.logical_flips.iter().all(std::vec::Vec::is_empty) + && self.tracked_op_flips.iter().all(std::vec::Vec::is_empty) && self.measurement_flips.iter().all(std::vec::Vec::is_empty) } @@ -334,11 +378,11 @@ impl FaultInfluence { .map_or(&[], |v| v.as_slice()) } - /// Returns all logicals flipped by a specific Pauli type. + /// Returns all tracked Pauli operators flipped by a specific Pauli type. #[inline] #[must_use] - pub fn logicals_for_pauli(&self, pauli: u8) -> &[LogicalId] { - self.logical_flips + pub fn tracked_ops_for_pauli(&self, pauli: u8) -> &[TrackedOpId] { + self.tracked_op_flips .get(pauli as usize) .map_or(&[], |v| v.as_slice()) } @@ -356,8 +400,8 @@ pub struct FaultInfluenceMap { /// All detectors in the circuit. pub detectors: Vec, - /// All logical observables being tracked. - pub logicals: Vec, + /// All tracked Pauli operators. + pub tracked_ops: Vec, /// All measurements in the circuit. pub measurements: Vec, @@ -365,8 +409,8 @@ pub struct FaultInfluenceMap { /// Reverse map: for each detector, which fault locations flip it. pub detector_to_faults: BTreeMap>, - /// Reverse map: for each logical, which fault locations flip it. - pub logical_to_faults: BTreeMap>, + /// Reverse map: for each tracked Pauli operator, which fault locations flip it. + pub tracked_op_to_faults: BTreeMap>, } impl FaultInfluenceMap { @@ -376,10 +420,10 @@ impl FaultInfluenceMap { Self { influences: BTreeMap::new(), detectors: Vec::new(), - logicals: Vec::new(), + tracked_ops: Vec::new(), measurements: Vec::new(), detector_to_faults: BTreeMap::new(), - logical_to_faults: BTreeMap::new(), + tracked_op_to_faults: BTreeMap::new(), } } @@ -391,14 +435,14 @@ impl FaultInfluenceMap { /// Quickly classifies a single-qubit fault based on pre-computed influences. /// - /// Returns (`has_syndrome`, `has_logical_error`) for the given Pauli type. + /// Returns (`has_syndrome`, `flips_tracked_op`) for the given Pauli type. /// For multi-qubit locations, use `classify_multi_qubit_fault` instead. #[must_use] pub fn classify_fault(&self, location: &SpacetimeLocation, pauli: u8) -> (bool, bool) { if let Some(influence) = self.influences.get(location) { let has_syndrome = !influence.detectors_for_pauli(pauli).is_empty(); - let has_logical = !influence.logicals_for_pauli(pauli).is_empty(); - (has_syndrome, has_logical) + let flips_tracked_op = !influence.tracked_ops_for_pauli(pauli).is_empty(); + (has_syndrome, flips_tracked_op) } else { (false, false) } @@ -413,7 +457,7 @@ impl FaultInfluenceMap { /// For Y faults, we decompose Y = XZ and combine the X and Z contributions, /// since Y anticommutes with both X and Z components of the observable. /// - /// Returns (`has_syndrome`, `has_logical_error`). + /// Returns (`has_syndrome`, `flips_tracked_op`). #[must_use] pub fn classify_multi_qubit_fault( &self, @@ -458,11 +502,11 @@ impl FaultInfluenceMap { // Syndrome = odd number of flips for any detector let has_syndrome = detector_flip_counts.values().any(|&count| count % 2 == 1); - // For logicals, use the same approach - // (simplified: just check if any qubit flips logical, proper handling TBD) - let has_logical = !influence.logicals_for_pauli(pauli).is_empty(); + // For tracked operators, use the same approach + // (simplified: just check if any component flips, proper handling TBD) + let flips_tracked_op = !influence.tracked_ops_for_pauli(pauli).is_empty(); - (has_syndrome, has_logical) + (has_syndrome, flips_tracked_op) } else { (false, false) } diff --git a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs new file mode 100644 index 000000000..5ef4e6293 --- /dev/null +++ b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs @@ -0,0 +1,639 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Targeted fault-catalog lookup decoder. +//! +//! Answers one detector syndrome at a time by searching the fault catalog, +//! instead of precomputing a full lookup table for every syndrome. +//! +//! Uses odds-space weights for efficient comparison: +//! - `base_probability = product of all (1 - p_i)` +//! - `odds_weight(alt) = alt.absolute_probability / (1 - p_i)` +//! - `configuration_probability = base_probability * product(selected odds_weights)` + +use super::fault_sampler::FaultCatalog; +use std::collections::{BTreeMap, BTreeSet, HashMap}; + +/// A flattened fault entry for index lookup. +#[derive(Clone, Debug)] +struct FaultEntry { + /// Index of the physical fault location in the catalog. + location_index: usize, + /// Detector effect as a sorted set of detector indices (XOR parity). + detector_bits: BTreeSet, + /// Observable/logical effect as a sorted set. + logical_bits: BTreeSet, + /// Odds-space weight: absolute_probability / no_fault_probability. + odds_weight: f64, +} + +/// Result of decoding a single syndrome. +#[derive(Clone, Debug)] +pub struct DecodeResult { + /// The queried syndrome. + pub syndrome: Vec, + /// Accumulated odds-space weights by logical class. + /// Multiply by `base_probability` for absolute probabilities. + pub logical_weights: BTreeMap, f64>, + /// The logical class with the highest weight. + pub best_logical: Vec, +} + +/// Targeted fault-catalog lookup decoder. +/// +/// Searches the fault catalog for explanations of a given detector syndrome, +/// accumulating odds-space weights by logical class up to `max_faults` +/// simultaneous fault locations. +pub struct TargetedLookupDecoder { + max_faults: usize, + base_prob: f64, + entries: Vec, + /// Index: detector_bits -> list of entry indices. + by_detector: HashMap, Vec>, +} + +impl TargetedLookupDecoder { + /// Build a decoder from a fault catalog. + pub fn new(catalog: &FaultCatalog) -> Self { + let base_prob: f64 = catalog + .locations + .iter() + .map(|loc| loc.no_fault_probability) + .product(); + + let mut entries = Vec::new(); + for (loc_idx, loc) in catalog.locations.iter().enumerate() { + for alt in &loc.faults { + let odds = if loc.no_fault_probability > 0.0 { + alt.absolute_probability / loc.no_fault_probability + } else { + f64::INFINITY + }; + entries.push(FaultEntry { + location_index: loc_idx, + detector_bits: alt.affected_detectors.iter().copied().collect(), + logical_bits: alt.affected_observables.iter().copied().collect(), + odds_weight: odds, + }); + } + } + + let mut by_detector: HashMap, Vec> = HashMap::new(); + for (i, entry) in entries.iter().enumerate() { + by_detector + .entry(entry.detector_bits.clone()) + .or_default() + .push(i); + } + + Self { + max_faults: 1, + base_prob, + entries, + by_detector, + } + } + + /// Set the maximum number of simultaneous fault locations to consider. + pub fn max_faults(mut self, max_faults: usize) -> Self { + self.max_faults = max_faults; + self + } + + /// The all-no-fault probability: product of (1 - p_i) for all locations. + pub fn base_probability(&self) -> f64 { + self.base_prob + } + + /// Decode a syndrome: find all explanations up to max_faults and accumulate + /// odds-space weights by logical class. + pub fn decode(&self, syndrome: &[usize]) -> DecodeResult { + let target: BTreeSet = syndrome.iter().copied().collect(); + let mut logical_weights: BTreeMap, f64> = BTreeMap::new(); + + // k=0: empty syndrome -> empty logical with weight 1 + if target.is_empty() { + *logical_weights.entry(Vec::new()).or_default() += 1.0; + } + + // k=1: direct lookup + if self.max_faults >= 1 { + if let Some(indices) = self.by_detector.get(&target) { + for &i in indices { + let e = &self.entries[i]; + let logical: Vec = e.logical_bits.iter().copied().collect(); + *logical_weights.entry(logical).or_default() += e.odds_weight; + } + } + } + + // k=2: complement lookup + if self.max_faults >= 2 { + self.search_k2(&target, &mut logical_weights); + } + + // k>=3: recursive exact search + if self.max_faults >= 3 { + for k in 3..=self.max_faults { + self.search_generic(k, &target, &mut logical_weights); + } + } + + let best_logical = logical_weights + .iter() + .max_by(|(_, a), (_, b)| a.total_cmp(b)) + .map(|(logical, _)| logical.clone()) + .unwrap_or_default(); + + DecodeResult { + syndrome: syndrome.to_vec(), + logical_weights, + best_logical, + } + } + + /// k=2 complement lookup: for each entry a, compute needed_b = target XOR a.detectors, + /// then look up entries with that detector effect. + fn search_k2(&self, target: &BTreeSet, logical_weights: &mut BTreeMap, f64>) { + for (i, a) in self.entries.iter().enumerate() { + let needed_b = xor_sets(target, &a.detector_bits); + if let Some(b_indices) = self.by_detector.get(&needed_b) { + for &j in b_indices { + if j <= i { + continue; // avoid double-counting (ordered pairs) + } + let b = &self.entries[j]; + if a.location_index == b.location_index { + continue; // same physical location + } + let logical = xor_sets(&a.logical_bits, &b.logical_bits); + let logical_vec: Vec = logical.into_iter().collect(); + *logical_weights.entry(logical_vec).or_default() += + a.odds_weight * b.odds_weight; + } + } + } + } + + /// Generic exact search for k >= 3. Recursive depth-first with location exclusion. + fn search_generic( + &self, + k: usize, + target: &BTreeSet, + logical_weights: &mut BTreeMap, f64>, + ) { + self.search_recursive( + k, + 0, // start_entry + target.clone(), + BTreeSet::new(), // used_locations + BTreeSet::new(), // logical_parity + 1.0, // odds_product + 0, // depth + logical_weights, + ); + } + + #[allow(clippy::too_many_arguments)] + fn search_recursive( + &self, + k: usize, + start_entry: usize, + needed: BTreeSet, + used_locations: BTreeSet, + logical_parity: BTreeSet, + odds_product: f64, + depth: usize, + logical_weights: &mut BTreeMap, f64>, + ) { + if depth == k { + if needed.is_empty() { + let logical_vec: Vec = logical_parity.into_iter().collect(); + *logical_weights.entry(logical_vec).or_default() += odds_product; + } + return; + } + + let remaining = k - depth; + for i in start_entry..self.entries.len() { + // Check if enough entries remain + if self.entries.len() - i < remaining { + break; + } + + let entry = &self.entries[i]; + + // Skip if this location is already used + if used_locations.contains(&entry.location_index) { + continue; + } + + let new_needed = xor_sets(&needed, &entry.detector_bits); + let new_logical = xor_sets(&logical_parity, &entry.logical_bits); + let new_odds = odds_product * entry.odds_weight; + + let mut new_used = used_locations.clone(); + new_used.insert(entry.location_index); + + self.search_recursive( + k, + i + 1, + new_needed, + new_used, + new_logical, + new_odds, + depth + 1, + logical_weights, + ); + } + } +} + +/// XOR two sorted sets (symmetric difference). +fn xor_sets(a: &BTreeSet, b: &BTreeSet) -> BTreeSet { + a.symmetric_difference(b).copied().collect() +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::fault_tolerance::fault_sampler::{ + build_fault_catalog, FaultCatalog, StochasticNoiseParams, + }; + use pecos_core::{gate_type::GateType, QubitId}; + use pecos_quantum::TickCircuit; + + /// Build a tiny circuit: H(0) CX(0,1) H(0) MZ(0) MZ(1) + /// with detector D0 = m0 XOR m1 and observable L0 = m1. + fn tiny_circuit() -> TickCircuit { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(1)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("2".to_string()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String(r#"[{"records": [-2, -1]}]"#.to_string()), + ); + tc.set_meta( + "observables", + pecos_quantum::Attribute::String(r#"[{"records": [-1]}]"#.to_string()), + ); + tc + } + + fn tiny_catalog() -> FaultCatalog { + let tc = tiny_circuit(); + let noise = StochasticNoiseParams { + p1: 0.003, + p2: 0.01, + p_meas: 0.005, + p_prep: 0.005, + }; + build_fault_catalog(&tc, &noise).unwrap() + } + + /// Brute-force reference: enumerate all configurations up to max_faults, + /// accumulate odds weights by (syndrome, logical). + fn brute_force_weights( + catalog: &FaultCatalog, + max_faults: usize, + ) -> BTreeMap, BTreeMap, f64>> { + let base: f64 = catalog + .locations + .iter() + .map(|l| l.no_fault_probability) + .product(); + let mut result: BTreeMap, BTreeMap, f64>> = BTreeMap::new(); + for k in 0..=max_faults { + for event in catalog.fault_configurations(k) { + let odds = if base > 0.0 { + event.configuration_probability / base + } else { + 0.0 + }; + *result + .entry(event.affected_detectors) + .or_default() + .entry(event.affected_observables) + .or_default() += odds; + } + } + result + } + + #[test] + fn test_k0_empty_syndrome() { + let catalog = tiny_catalog(); + let decoder = TargetedLookupDecoder::new(&catalog).max_faults(0); + let result = decoder.decode(&[]); + assert_eq!(result.best_logical, Vec::::new()); + assert!((result.logical_weights[&vec![]] - 1.0).abs() < 1e-12); + } + + #[test] + fn test_unexplainable_syndrome_returns_empty_weights() { + let mut tc = TickCircuit::new(); + tc.tick().mz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(1)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("2".into()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String(r#"[{"records":[-2]},{"records":[-1]}]"#.into()), + ); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let noise = StochasticNoiseParams { + p1: 0.0, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + + let zero_fault_decoder = TargetedLookupDecoder::new(&catalog).max_faults(0); + let zero_fault_result = zero_fault_decoder.decode(&[0]); + assert!( + zero_fault_result.logical_weights.is_empty(), + "non-empty syndrome cannot be explained by zero faults" + ); + + let one_fault_decoder = TargetedLookupDecoder::new(&catalog).max_faults(1); + let one_fault_result = one_fault_decoder.decode(&[0, 1]); + assert!( + one_fault_result.logical_weights.is_empty(), + "syndrome [0, 1] requires two distinct measurement faults" + ); + } + + #[test] + fn test_k1_matches_brute_force() { + let catalog = tiny_catalog(); + let decoder = TargetedLookupDecoder::new(&catalog).max_faults(1); + let bf = brute_force_weights(&catalog, 1); + + for (syndrome, bf_logicals) in &bf { + let result = decoder.decode(syndrome); + for (logical, &bf_weight) in bf_logicals { + let dec_weight = result.logical_weights.get(logical).copied().unwrap_or(0.0); + assert!( + (dec_weight - bf_weight).abs() < 1e-12, + "k=1 mismatch for syndrome={syndrome:?} logical={logical:?}: \ + decoder={dec_weight} brute_force={bf_weight}" + ); + } + } + } + + #[test] + fn test_k2_matches_brute_force() { + let catalog = tiny_catalog(); + let decoder = TargetedLookupDecoder::new(&catalog).max_faults(2); + let bf = brute_force_weights(&catalog, 2); + + for (syndrome, bf_logicals) in &bf { + let result = decoder.decode(syndrome); + for (logical, &bf_weight) in bf_logicals { + let dec_weight = result.logical_weights.get(logical).copied().unwrap_or(0.0); + assert!( + (dec_weight - bf_weight).abs() / bf_weight.max(1e-15) < 1e-8, + "k=2 mismatch for syndrome={syndrome:?} logical={logical:?}: \ + decoder={dec_weight:.6e} brute_force={bf_weight:.6e}" + ); + } + } + } + + #[test] + fn test_new_clifford_gate_circuit_matches_brute_force() { + let mut tc = TickCircuit::new(); + tc.tick().sx(&[QubitId(0)]); + tc.tick().cy(&[(QubitId(0), QubitId(1))]); + tc.tick().sxx(&[(QubitId(0), QubitId(1))]); + tc.tick().swap(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(1)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("2".into()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String( + r#"[{"records":[-2]},{"records":[-1]},{"records":[-2,-1]}]"#.into(), + ), + ); + tc.set_meta( + "observables", + pecos_quantum::Attribute::String(r#"[{"records":[-1]}]"#.into()), + ); + + let noise = StochasticNoiseParams { + p1: 0.003, + p2: 0.01, + p_meas: 0.0, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + assert!(catalog + .locations + .iter() + .any(|loc| loc.gate_type == GateType::SX)); + assert!(catalog + .locations + .iter() + .any(|loc| loc.gate_type == GateType::CY)); + assert!(catalog + .locations + .iter() + .any(|loc| loc.gate_type == GateType::SXX)); + assert!(catalog + .locations + .iter() + .any(|loc| loc.gate_type == GateType::SWAP)); + + let decoder = TargetedLookupDecoder::new(&catalog).max_faults(2); + let bf = brute_force_weights(&catalog, 2); + for (syndrome, bf_logicals) in &bf { + let result = decoder.decode(syndrome); + for (logical, &bf_weight) in bf_logicals { + let dec_weight = result.logical_weights.get(logical).copied().unwrap_or(0.0); + assert!( + (dec_weight - bf_weight).abs() / bf_weight.max(1e-15) < 1e-8, + "new-gate decoder mismatch for syndrome={syndrome:?} logical={logical:?}: \ + decoder={dec_weight:.6e} brute_force={bf_weight:.6e}" + ); + } + } + } + + #[test] + fn test_k3_matches_brute_force() { + // Very small circuit to keep k=3 tractable + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".into()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String(r#"[{"records":[-1]}]"#.into()), + ); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let noise = StochasticNoiseParams { + p1: 0.01, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.01, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + let decoder = TargetedLookupDecoder::new(&catalog).max_faults(3); + let bf = brute_force_weights(&catalog, 3); + + for (syndrome, bf_logicals) in &bf { + let result = decoder.decode(syndrome); + for (logical, &bf_weight) in bf_logicals { + let dec_weight = result.logical_weights.get(logical).copied().unwrap_or(0.0); + assert!( + (dec_weight - bf_weight).abs() / bf_weight.max(1e-15) < 1e-8, + "k=3 mismatch for syndrome={syndrome:?} logical={logical:?}: \ + decoder={dec_weight:.6e} brute_force={bf_weight:.6e}" + ); + } + } + } + + #[test] + fn test_cancellation() { + // Construct a catalog where syndrome {0} is explained by + // {0,1} XOR {1} (two faults cancelling detector 1). + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.tick().mz(&[QubitId(1)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("2".into()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String(r#"[{"records":[-2]},{"records":[-1]}]"#.into()), + ); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let noise = StochasticNoiseParams { + p1: 0.01, + p2: 0.01, + p_meas: 0.01, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + let decoder = TargetedLookupDecoder::new(&catalog).max_faults(2); + + // Check that syndrome [0] has k=2 explanations + let result = decoder.decode(&[0]); + let bf = brute_force_weights(&catalog, 2); + if let Some(bf_logicals) = bf.get(&vec![0]) { + for (logical, &bf_weight) in bf_logicals { + let dec_weight = result.logical_weights.get(logical).copied().unwrap_or(0.0); + assert!( + (dec_weight - bf_weight).abs() / bf_weight.max(1e-15) < 1e-8, + "Cancellation test mismatch" + ); + } + } + } + + #[test] + fn test_same_location_exclusion() { + let catalog = tiny_catalog(); + let decoder = TargetedLookupDecoder::new(&catalog).max_faults(2); + + // Brute force already enforces location exclusion. + // Verify decoder matches for all syndromes. + let bf = brute_force_weights(&catalog, 2); + for (syndrome, bf_logicals) in &bf { + let result = decoder.decode(syndrome); + for (logical, &bf_weight) in bf_logicals { + let dec_weight = result.logical_weights.get(logical).copied().unwrap_or(0.0); + assert!( + (dec_weight - bf_weight).abs() / bf_weight.max(1e-15) < 1e-8, + "Location exclusion mismatch at syndrome={syndrome:?}" + ); + } + } + } + + #[test] + fn test_empty_syndrome_with_silent_alternatives() { + // Empty-detector alternatives contribute to empty syndrome + let catalog = tiny_catalog(); + let decoder = TargetedLookupDecoder::new(&catalog).max_faults(1); + let result = decoder.decode(&[]); + + // k=0 contributes weight 1.0 for empty logical. + // k=1 empty-detector alternatives also contribute. + assert!( + result.logical_weights.contains_key(&vec![]), + "Empty logical should appear for empty syndrome" + ); + assert!( + *result.logical_weights.get(&vec![]).unwrap() >= 1.0, + "Empty-syndrome weight should be >= 1.0 (k=0 contributes 1)" + ); + } + + #[test] + fn test_odds_to_absolute_probability() { + let catalog = tiny_catalog(); + let decoder = TargetedLookupDecoder::new(&catalog).max_faults(1); + let result = decoder.decode(&[0]); + + // Sum of odds weights * base_probability = sum of configuration_probabilities + let total_odds: f64 = result.logical_weights.values().sum(); + let total_abs = total_odds * decoder.base_probability(); + assert!(total_abs > 0.0, "Should have nonzero absolute probability"); + assert!(total_abs < 1.0, "Total probability should be < 1"); + } + + #[test] + fn test_k2_no_double_counting() { + let catalog = tiny_catalog(); + let decoder = TargetedLookupDecoder::new(&catalog).max_faults(2); + let bf = brute_force_weights(&catalog, 2); + + // Check EVERY brute-force entry matches decoder exactly + for (syndrome, bf_logicals) in &bf { + let result = decoder.decode(syndrome); + let total_bf: f64 = bf_logicals.values().sum(); + let total_dec: f64 = result.logical_weights.values().sum(); + assert!( + (total_dec - total_bf).abs() / total_bf.max(1e-15) < 1e-8, + "k=2 total weight mismatch at syndrome={syndrome:?}: \ + decoder={total_dec:.6e} brute_force={total_bf:.6e}" + ); + } + } +} diff --git a/crates/pecos-qec/src/lib.rs b/crates/pecos-qec/src/lib.rs index 9ac2a135e..0282ce384 100644 --- a/crates/pecos-qec/src/lib.rs +++ b/crates/pecos-qec/src/lib.rs @@ -76,19 +76,20 @@ pub use distance::{ calculate_distance, find_min_weight_logicals, find_min_weight_logicals_with_info, }; pub use fault_tolerance::dem_builder::{ - DecomposedError, DemBuilder, DemBuilderError, DetectorDef, DetectorErrorModel, ErrorMechanism, - LogicalObservable, NoiseConfig, combine_probabilities, + DecomposedFault, DemBuilder, DemBuilderError, DemOutput, DetectorDef, DetectorErrorModel, + FaultMechanism, NoiseConfig, PecosDemMetadataError, combine_probabilities, }; pub use fault_tolerance::{ - CorrectionResult, DecoderAnalysis, ErrorClass, ErrorCorrectionChecker, ErrorCorrectionConfig, - ErrorCorrectionResult, FaultCheckConfig, FaultCheckResult, FaultChecker, FaultClass, - FaultConfiguration, FaultToleranceAnalysis, FaultToleranceFailure, LookupTableDecoder, - MeasurementRound, PauliFault, PauliFaultIterator, PauliPropChecker, PropagationResult, - SpacetimeLocation, StabilizerFlipAnalysis, StabilizerFlipChecker, StabilizerFlips, - SyndromeAnalysis, SyndromeClass, SyndromeHistory, SyndromeHistoryAnalysis, - SyndromeHistoryResult, anticommutes_with_logical, apply_recovery, classify_fault, - extract_measurement_rounds, extract_spacetime_locations, extract_syndrome, get_syndrome_flips, - has_syndrome, propagate_fault, propagate_faults, run_circuit_with_faults, run_correction_cycle, + CorrectionResult, DecoderAnalysis, DemOutputKind, DemOutputMetadata, ErrorClass, + ErrorCorrectionChecker, ErrorCorrectionConfig, ErrorCorrectionResult, FaultCheckConfig, + FaultCheckResult, FaultChecker, FaultClass, FaultConfiguration, FaultToleranceAnalysis, + FaultToleranceFailure, LookupTableDecoder, MeasurementRound, PauliFault, PauliFaultIterator, + PauliPropChecker, PropagationResult, SpacetimeLocation, StabilizerFlipAnalysis, + StabilizerFlipChecker, StabilizerFlips, SyndromeAnalysis, SyndromeClass, SyndromeHistory, + SyndromeHistoryAnalysis, SyndromeHistoryResult, anticommutes_with_logical, apply_recovery, + classify_fault, extract_measurement_rounds, extract_spacetime_locations, extract_syndrome, + get_syndrome_flips, has_syndrome, propagate_fault, propagate_faults, run_circuit_with_faults, + run_correction_cycle, }; pub use geometry::{CheckSchedule, LogicalOperator, PauliOp, StabilizerCheck, StabilizerColor}; pub use logical_discovery::{ diff --git a/crates/pecos-qec/tests/dem_sampler_tests.rs b/crates/pecos-qec/tests/dem_sampler_tests.rs index 46566dd08..f30fcdbe9 100644 --- a/crates/pecos-qec/tests/dem_sampler_tests.rs +++ b/crates/pecos-qec/tests/dem_sampler_tests.rs @@ -20,11 +20,10 @@ //! 3. Consistency with MNM (Measurement Noise Model) //! 4. Edge cases and boundary conditions -use pecos_qec::fault_tolerance::dem_builder::{DemSamplerBuilder, MemBuilder}; +use pecos_qec::fault_tolerance::dem_builder::DemSamplerBuilder; use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; use pecos_quantum::DagCircuit; -use rand::SeedableRng; -use rand::rngs::SmallRng; +use pecos_random::PecosRng; // ============================================================================ // Test Helpers @@ -74,12 +73,13 @@ fn test_zero_noise_produces_no_errors() { .with_noise(0.0, 0.0, 0.0, 0.0) .with_detectors_json(detectors_json) .unwrap() - .build(); + .build() + .unwrap(); // Zero noise should produce zero mechanisms assert_eq!(sampler.num_mechanisms(), 0); - let mut rng = SmallRng::seed_from_u64(42); + let mut rng = PecosRng::seed_from_u64(42); let stats = sampler.sample_statistics_with_rng(1000, &mut rng); assert_eq!(stats.logical_error_count, 0); @@ -102,13 +102,15 @@ fn test_mechanism_count_scales_with_circuit() { .with_noise(0.01, 0.01, 0.01, 0.01) .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) .unwrap() - .build(); + .build() + .unwrap(); let sampler2 = DemSamplerBuilder::new(&im2) .with_noise(0.01, 0.01, 0.01, 0.01) .with_detectors_json(r#"[{"id": 0, "records": [-2]}, {"id": 1, "records": [-1]}]"#) .unwrap() - .build(); + .build() + .unwrap(); // Larger circuit should have more mechanisms assert!( @@ -129,11 +131,12 @@ fn test_deterministic_sampling_with_seed() { .with_noise(0.1, 0.1, 0.1, 0.1) .with_detectors_json(detectors_json) .unwrap() - .build(); + .build() + .unwrap(); // Same seed should produce same results - let mut rng1 = SmallRng::seed_from_u64(12345); - let mut rng2 = SmallRng::seed_from_u64(12345); + let mut rng1 = PecosRng::seed_from_u64(12345); + let mut rng2 = PecosRng::seed_from_u64(12345); let (det1, obs1) = sampler.sample_batch(100, &mut rng1); let (det2, obs2) = sampler.sample_batch(100, &mut rng2); @@ -154,10 +157,11 @@ fn test_different_seeds_produce_different_results() { .with_noise(0.1, 0.1, 0.1, 0.1) .with_detectors_json(detectors_json) .unwrap() - .build(); + .build() + .unwrap(); - let mut rng1 = SmallRng::seed_from_u64(12345); - let mut rng2 = SmallRng::seed_from_u64(54321); + let mut rng1 = PecosRng::seed_from_u64(12345); + let mut rng2 = PecosRng::seed_from_u64(54321); let (det1, _) = sampler.sample_batch(100, &mut rng1); let (det2, _) = sampler.sample_batch(100, &mut rng2); @@ -182,15 +186,17 @@ fn test_syndrome_rate_scales_with_noise() { .with_noise(0.001, 0.001, 0.001, 0.001) .with_detectors_json(detectors_json) .unwrap() - .build(); + .build() + .unwrap(); let sampler_high = DemSamplerBuilder::new(&influence_map) .with_noise(0.05, 0.05, 0.05, 0.05) .with_detectors_json(detectors_json) .unwrap() - .build(); + .build() + .unwrap(); - let mut rng = SmallRng::seed_from_u64(42); + let mut rng = PecosRng::seed_from_u64(42); let stats_low = sampler_low.sample_statistics_with_rng(10000, &mut rng); let stats_high = sampler_high.sample_statistics_with_rng(10000, &mut rng); @@ -217,9 +223,10 @@ fn test_syndrome_rate_reasonable_magnitude() { .with_noise(p, p, p, p) .with_detectors_json(detectors_json) .unwrap() - .build(); + .build() + .unwrap(); - let mut rng = SmallRng::seed_from_u64(42); + let mut rng = PecosRng::seed_from_u64(42); let stats = sampler.sample_statistics_with_rng(100_000, &mut rng); // With p=0.01, syndrome rate should be in a reasonable range @@ -253,17 +260,18 @@ fn test_observable_tracking() { .unwrap() .with_observables_json(observables_json) .unwrap() - .build(); + .build() + .unwrap(); assert_eq!(sampler.num_observables(), 1); - let mut rng = SmallRng::seed_from_u64(42); + let mut rng = PecosRng::seed_from_u64(42); let stats = sampler.sample_statistics_with_rng(10000, &mut rng); - // With observable tracking, we should see some logical errors + // With observable tracking, we should see some observable errors assert!( stats.logical_error_rate() > 0.0, - "Expected some logical errors with noise" + "Expected some observable errors with noise" ); } @@ -281,11 +289,12 @@ fn test_empty_detector_definitions() { .with_noise(0.01, 0.01, 0.01, 0.01) .with_detectors_json("[]") .unwrap() - .build(); + .build() + .unwrap(); assert_eq!(sampler.num_detectors(), 0); - let mut rng = SmallRng::seed_from_u64(42); + let mut rng = PecosRng::seed_from_u64(42); let (det_events, _) = sampler.sample(&mut rng); assert!(det_events.is_empty()); @@ -305,12 +314,13 @@ fn test_single_qubit_circuit() { .with_noise(0.01, 0.01, 0.01, 0.01) .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) .unwrap() - .build(); + .build() + .unwrap(); // Should have mechanisms from prep, H gate, and measurement assert!(sampler.num_mechanisms() > 0); - let mut rng = SmallRng::seed_from_u64(42); + let mut rng = PecosRng::seed_from_u64(42); let stats = sampler.sample_statistics_with_rng(1000, &mut rng); // Should produce some syndromes @@ -327,14 +337,15 @@ fn test_only_measurement_noise() { .with_noise(0.0, 0.0, 0.1, 0.0) // Only measurement noise .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) .unwrap() - .build(); + .build() + .unwrap(); assert!( sampler.num_mechanisms() > 0, "Should have mechanisms from measurement noise" ); - let mut rng = SmallRng::seed_from_u64(42); + let mut rng = PecosRng::seed_from_u64(42); let stats = sampler.sample_statistics_with_rng(10000, &mut rng); // Should produce syndromes from measurement errors @@ -354,14 +365,15 @@ fn test_only_two_qubit_noise() { .with_noise(0.0, 0.1, 0.0, 0.0) // Only two-qubit noise .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) .unwrap() - .build(); + .build() + .unwrap(); assert!( sampler.num_mechanisms() > 0, "Should have mechanisms from two-qubit noise" ); - let mut rng = SmallRng::seed_from_u64(42); + let mut rng = PecosRng::seed_from_u64(42); let stats = sampler.sample_statistics_with_rng(10000, &mut rng); // Should produce syndromes from CX errors @@ -384,24 +396,26 @@ fn test_dem_sampler_vs_mnm_mechanism_structure() { let p1 = 0.01; let p2 = 0.01; let p_meas = 0.01; - let p_init = 0.01; - - // Build MNM for comparison - let mnm = MemBuilder::new(&influence_map) - .with_noise(p1, p2, p_meas, p_init) - .build(); - - // Build DemSampler - let sampler = DemSamplerBuilder::new(&influence_map) - .with_noise(p1, p2, p_meas, p_init) - .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) - .unwrap() - .build(); - - // MNM mechanisms are at measurement level, DemSampler at detector level - // They should both have non-zero counts - assert!(mnm.num_mechanisms() > 0); - assert!(sampler.num_mechanisms() > 0); + let p_prep = 0.01; + + // DemSampler raw mode (replaces MemBuilder) + let raw_sampler = DemSamplerBuilder::new(&influence_map) + .with_noise(p1, p2, p_meas, p_prep) + .raw_measurements() + .build() + .unwrap(); + + // DemSampler detector mode (replaces DemSamplerBuilder for this use case) + let det_records = vec![vec![-1i32]]; + let det_sampler = DemSamplerBuilder::new(&influence_map) + .with_noise(p1, p2, p_meas, p_prep) + .with_detectors(det_records, vec![]) + .build() + .unwrap(); + + // Both should have non-zero mechanism counts + assert!(raw_sampler.num_mechanisms() > 0); + assert!(det_sampler.num_mechanisms() > 0); } #[test] @@ -419,11 +433,12 @@ fn test_multi_detector_circuit() { .with_noise(0.01, 0.01, 0.01, 0.01) .with_detectors_json(detectors_json) .unwrap() - .build(); + .build() + .unwrap(); assert_eq!(sampler.num_detectors(), 2); - let mut rng = SmallRng::seed_from_u64(42); + let mut rng = PecosRng::seed_from_u64(42); let (det_events, _) = sampler.sample_batch(1000, &mut rng); // Should get events on both detectors @@ -448,9 +463,10 @@ fn test_batch_sampling_performance() { .with_noise(0.01, 0.01, 0.01, 0.01) .with_detectors_json(r#"[{"id": 0, "records": [-2]}, {"id": 1, "records": [-1]}]"#) .unwrap() - .build(); + .build() + .unwrap(); - let mut rng = SmallRng::seed_from_u64(42); + let mut rng = PecosRng::seed_from_u64(42); // Should be able to sample many shots quickly let num_shots = 100_000; @@ -483,21 +499,22 @@ fn test_statistics_vs_batch_consistency() { .unwrap() .with_observables_json(observables_json) .unwrap() - .build(); + .build() + .unwrap(); let num_shots = 10000; // Sample with statistics method (uses geometric skip) - let mut rng1 = SmallRng::seed_from_u64(42); + let mut rng1 = PecosRng::seed_from_u64(42); let stats = sampler.sample_statistics_with_rng(num_shots, &mut rng1); // Sample with batch method (uses per-shot threshold) - let mut rng2 = SmallRng::seed_from_u64(123); // Different seed since algorithms differ + let mut rng2 = PecosRng::seed_from_u64(123); // Different seed since algorithms differ let (det_events, obs_flips) = sampler.sample_batch(num_shots, &mut rng2); // Count from batch results let batch_syndromes = det_events.iter().filter(|d| d.iter().any(|&x| x)).count(); - let batch_logical = obs_flips.iter().filter(|o| o.iter().any(|&x| x)).count(); + let batch_observable = obs_flips.iter().filter(|o| o.iter().any(|&x| x)).count(); // Should be statistically similar (within 10% relative difference) let stats_rate = stats.syndrome_count as f64 / num_shots as f64; @@ -509,11 +526,11 @@ fn test_statistics_vs_batch_consistency() { ); let stats_logical_rate = stats.logical_error_count as f64 / num_shots as f64; - let batch_logical_rate = batch_logical as f64 / num_shots as f64; - let logical_rel_diff = (stats_logical_rate - batch_logical_rate).abs() + let batch_logical_rate = batch_observable as f64 / num_shots as f64; + let observable_rel_diff = (stats_logical_rate - batch_logical_rate).abs() / stats_logical_rate.max(batch_logical_rate).max(0.001); assert!( - logical_rel_diff < 0.1, - "Logical error rates should be similar: stats={stats_logical_rate:.4} batch={batch_logical_rate:.4} rel_diff={logical_rel_diff:.2}" + observable_rel_diff < 0.1, + "Logical error rates should be similar: stats={stats_logical_rate:.4} batch={batch_logical_rate:.4} rel_diff={observable_rel_diff:.2}" ); } diff --git a/crates/pecos-qec/tests/fault_enumeration_example.rs b/crates/pecos-qec/tests/fault_enumeration_example.rs new file mode 100644 index 000000000..c9164f4ad --- /dev/null +++ b/crates/pecos-qec/tests/fault_enumeration_example.rs @@ -0,0 +1,792 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +// Shot counts and error counters are small integers; precision loss in f64 is not a concern. +#![allow(clippy::cast_precision_loss)] + +//! Example: Repetition code d=3 with 3 rounds of syndrome extraction. +//! +//! Demonstrates the full QEC workflow: +//! 1. Build the circuit with annotations (detectors, observables, Pauli operators) +//! 2. Build the fault influence map +//! 3. Enumerate fault combinations up to weight 3 +//! 4. Classify errors (detectable, undetectable, logical) + +use pecos_core::pauli::constructors::X; +use pecos_qec::fault_tolerance::InfluenceBuilder; +use pecos_quantum::DagCircuit; + +/// Build a repetition code d=3 circuit with `num_rounds` syndrome extraction rounds. +/// +/// Layout: +/// Data qubits: 0, 1, 2 +/// Z-ancillas: 3 (measures `Z_0` `Z_1`), 4 (measures `Z_1` `Z_2`) +/// +/// Each round: prep ancillas, CNOT syndrome extraction, measure ancillas. +/// After the last round: measure all data qubits for final readout. +fn build_repetition_code(num_rounds: usize) -> DagCircuit { + let mut dag = DagCircuit::new(); + + // Data qubits + let data: Vec = vec![0, 1, 2]; + // Ancilla qubits: one per stabilizer + let ancilla_01 = 3; // measures Z_0 Z_1 + let ancilla_12 = 4; // measures Z_1 Z_2 + + // Initialize data qubits in |0⟩ + dag.pz(&data); + + // Track measurements across rounds for detector definitions + let mut prev_meas_01 = None; + let mut prev_meas_12 = None; + + for round in 0..num_rounds { + // Prep ancillas + dag.pz(&[ancilla_01, ancilla_12]); + + // Syndrome extraction: CX from data to ancilla + // Z_0 Z_1 stabilizer + dag.cx(&[(data[0], ancilla_01)]); + dag.cx(&[(data[1], ancilla_01)]); + // Z_1 Z_2 stabilizer + dag.cx(&[(data[1], ancilla_12)]); + dag.cx(&[(data[2], ancilla_12)]); + + // Measure ancillas + let ms_01 = dag.mz(&[ancilla_01]); + let ms_12 = dag.mz(&[ancilla_12]); + + // Detectors + if round == 0 { + // First round: each measurement should be 0 (fresh code state) + dag.detector_labeled(&format!("Z01_r{round}"), &[ms_01[0]]); + dag.detector_labeled(&format!("Z12_r{round}"), &[ms_12[0]]); + } else { + // Subsequent rounds: compare with previous round + dag.detector_labeled(&format!("Z01_r{round}"), &[prev_meas_01.unwrap(), ms_01[0]]); + dag.detector_labeled(&format!("Z12_r{round}"), &[prev_meas_12.unwrap(), ms_12[0]]); + } + + prev_meas_01 = Some(ms_01[0]); + prev_meas_12 = Some(ms_12[0]); + } + + // Final data qubit measurements + let ms_data = dag.mz(&data); + + // Final detectors: compare last syndrome round with data measurements + // Z_0 Z_1 from data should match last ancilla measurement + dag.detector_labeled( + "Z01_final", + &[ms_data[0], ms_data[1], prev_meas_01.unwrap()], + ); + // Z_1 Z_2 from data should match last ancilla measurement + dag.detector_labeled( + "Z12_final", + &[ms_data[1], ms_data[2], prev_meas_12.unwrap()], + ); + + // Observable: logical Z readout = Z_0 (any single data qubit works for rep code) + dag.observable_labeled("logical_Z", &[ms_data[0]]); + + // Pauli operator: track logical X = X_0 X_1 X_2 + dag.pauli_operator_labeled("logical_X", X(0) & X(1) & X(2)); + + dag +} + +#[test] +fn repetition_code_fault_enumeration() { + let dag = build_repetition_code(3); + + println!("Circuit: {} gates", dag.gate_count()); + println!("Annotations:"); + for ann in dag.annotations() { + let kind = match &ann.kind { + pecos_quantum::AnnotationKind::Detector { .. } => "detector", + pecos_quantum::AnnotationKind::Observable { .. } => "observable", + pecos_quantum::AnnotationKind::Operator => "operator", + }; + let label = ann.label.as_deref().unwrap_or("(none)"); + println!(" {kind:10} {label:15} {}", ann.pauli); + } + + // Build influence map (InfluenceBuilder handles annotations) + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + let locs = map.gate_fault_locations(); + println!( + "\nFault locations: {} (grouped from {} per-qubit locations)", + locs.len(), + map.locations.len() + ); + println!( + "Detectors: {}, DEM outputs: {}", + map.detectors.len(), + map.influences.max_dem_output_index().map_or(0, |i| i + 1) + ); + + // Show all fault locations and their possible faults + println!("\n--- Fault locations ---"); + for (i, loc) in locs.iter().enumerate() { + let timing = if loc.before { "before" } else { "after" }; + let qubit_list: Vec = loc.qubits.iter().map(pecos_core::QubitId::index).collect(); + let num_faults = loc.possible_faults().len(); + println!( + " loc {i:2}: {:3?} {timing:6} qubits={qubit_list:?} ({num_faults} faults)", + loc.gate_type + ); + } + + // Weight-1 analysis + let mut w1_detectable = 0usize; + let mut w1_undetectable = 0usize; + let mut w1_trivial = 0usize; + let mut w1_total = 0usize; + + map.for_each_fault_combo(1, |combo| { + w1_total += 1; + let has_det = !combo.effect.detectors.is_empty(); + let has_dem_output = !combo.effect.dem_outputs.is_empty(); + match (has_det, has_dem_output) { + (true, _) => w1_detectable += 1, + (false, true) => w1_undetectable += 1, + (false, false) => w1_trivial += 1, + } + }); + println!("\n--- Weight-1 faults ---"); + println!(" Total: {w1_total}"); + println!(" Detectable: {w1_detectable}"); + println!(" Undetectable: {w1_undetectable}"); + println!(" Trivial: {w1_trivial}"); + // The repetition code only detects X errors (via Z stabilizers). + // Z errors on data qubits are undetectable -- this is expected. + // The undetectable errors flip logical_X (index 1) since Z anticommutes with X. + assert!( + w1_undetectable > 0, + "Z errors should be undetectable in the repetition code" + ); + + // Weight-2 analysis + let mut w2_detectable = 0usize; + let mut w2_undetectable = 0usize; + let mut w2_trivial = 0usize; + let mut w2_total = 0usize; + + map.for_each_fault_combo(2, |combo| { + w2_total += 1; + let has_det = !combo.effect.detectors.is_empty(); + let has_dem_output = !combo.effect.dem_outputs.is_empty(); + match (has_det, has_dem_output) { + (true, _) => w2_detectable += 1, + (false, true) => w2_undetectable += 1, + (false, false) => w2_trivial += 1, + } + }); + println!("\n--- Weight-2 faults ---"); + println!(" Total: {w2_total}"); + println!(" Detectable: {w2_detectable}"); + println!(" Undetectable: {w2_undetectable}"); + println!(" Trivial: {w2_trivial}"); + // Weight-2 also has undetectable Z errors (Z type is not protected). + + // Weight-3: this is where d=3 codes can have undetectable errors + let mut w3_detectable = 0usize; + let mut w3_undetectable = 0usize; + let mut w3_trivial = 0usize; + let mut w3_total = 0usize; + let mut w3_undetectable_examples: Vec = Vec::new(); + + map.for_each_fault_combo(3, |combo| { + w3_total += 1; + let has_det = !combo.effect.detectors.is_empty(); + let has_dem_output = !combo.effect.dem_outputs.is_empty(); + match (has_det, has_dem_output) { + (true, _) => w3_detectable += 1, + (false, true) => { + w3_undetectable += 1; + // Collect first few examples + if w3_undetectable_examples.len() < 5 { + let desc: Vec = combo + .components + .iter() + .map(|c| { + let loc = &locs[c.location_index]; + let timing = if loc.before { "before" } else { "after" }; + format!( + "{} {} {:?} q={:?}", + c.event.pauli, + timing, + loc.gate_type, + loc.qubits + .iter() + .map(pecos_core::QubitId::index) + .collect::>() + ) + }) + .collect(); + w3_undetectable_examples.push(desc.join(" + ")); + } + } + (false, false) => w3_trivial += 1, + } + }); + println!("\n--- Weight-3 faults ---"); + println!(" Total: {w3_total}"); + println!(" Detectable: {w3_detectable}"); + println!(" Undetectable: {w3_undetectable}"); + println!(" Trivial: {w3_trivial}"); + + if !w3_undetectable_examples.is_empty() { + println!("\n Example undetectable w=3 errors:"); + for ex in &w3_undetectable_examples { + println!(" {ex}"); + } + } + + // The d=3 repetition code can correct any single fault, so: + // - No undetectable errors at w=1 or w=2 + // - Some undetectable errors at w=3 (this is the code distance) + println!("\n--- Summary ---"); + println!(" The repetition code detects X errors (via Z stabilizers) but not Z errors."); + println!(" Undetectable errors at all weights are Z-type faults flipping logical_X."); + + // Also demonstrate single-event introspection + println!("\n--- Single event example ---"); + let first_cx_loc = locs + .iter() + .find(|l| l.gate_type == pecos_core::gate_type::GateType::CX && !l.before); + if let Some(loc) = first_cx_loc { + let qubit_list: Vec = loc.qubits.iter().map(pecos_core::QubitId::index).collect(); + println!(" CX after, qubits={qubit_list:?}:"); + for event in loc.events() { + if !event.detectors.is_empty() || !event.dem_outputs.is_empty() { + println!( + " {} -> dets={:?} dem_outputs={:?} meas={:?}", + event.pauli, event.detectors, event.dem_outputs, event.measurements + ); + } + } + } +} + +/// Test that labels are accessible from the influence map during fault introspection. +#[test] +fn repetition_code_labels() { + let dag = build_repetition_code(1); // 1 round for simplicity + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + // Check DEM-output labels are populated + println!("DEM output labels: {:?}", map.dem_output_labels); + assert_eq!(map.dem_output_labels.len(), 2); + assert_eq!(map.dem_output_labels[0].as_deref(), Some("logical_Z")); + assert_eq!(map.dem_output_labels[1].as_deref(), Some("logical_X")); + + // Labels accessible via index + assert_eq!(map.dem_output_label(0), Some("logical_Z")); + assert_eq!(map.dem_output_label(1), Some("logical_X")); + assert_eq!(map.dem_output_label(99), None); + + // Use labels during fault introspection + let locs = map.gate_fault_locations(); + let mut found_labeled_event = false; + for loc in &locs { + for event in loc.events() { + for &output_idx in &event.dem_outputs { + if let Some(label) = map.dem_output_label(output_idx as usize) { + println!(" {} at {:?} flips {label}", event.pauli, loc.gate_type); + found_labeled_event = true; + } + } + } + } + assert!( + found_labeled_event, + "Should find at least one labeled logical event" + ); +} + +/// Demonstrate building a lookup table from the influence map. +#[test] +fn repetition_code_lookup_table() { + let dag = build_repetition_code(3); + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + // Build lookup: syndrome pattern -> list of possible logical effects + let mut lookup: std::collections::BTreeMap, Vec> = + std::collections::BTreeMap::new(); + + // Weight-1 faults define the basic lookup + map.for_each_fault_combo(1, |combo| { + if !combo.effect.detectors.is_empty() { + let mut syndrome = combo.effect.detectors.clone(); + syndrome.sort_unstable(); + lookup + .entry(syndrome) + .or_default() + .push(combo.effect.pauli.clone()); + } + }); + + println!("Lookup table (weight-1 syndromes):"); + for (syndrome, faults) in &lookup { + println!(" syndrome {syndrome:?} <- {} fault(s)", faults.len()); + } + + // Verify: each non-trivial weight-1 syndrome maps to a correction + assert!( + !lookup.is_empty(), + "Should have at least one syndrome pattern" + ); +} + +/// Build an ML lookup table decoder and test it against sampled errors. +#[test] +fn repetition_code_ml_decoder() { + use pecos_qec::fault_tolerance::dem_builder::{DemSampler, NoiseConfig}; + use pecos_qec::fault_tolerance::lookup_decoder::LookupDecoder; + use rand::SeedableRng; + + let dag = build_repetition_code(3); + let noise = NoiseConfig::uniform(0.001); + + // Build influence map + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + // Build ML decoder from fault enumeration up to weight 3 + let decoder = LookupDecoder::build(&map, &noise, 3); + + println!("ML Decoder:"); + println!(" Syndrome patterns: {}", decoder.num_syndromes()); + println!(" Observables: {}", decoder.num_observables()); + println!(" Max weight: {}", decoder.max_weight()); + + // Build sampler for testing + let sampler = DemSampler::from_circuit(&dag, noise).unwrap(); + + // Sample and decode + let mut rng = rand::rngs::SmallRng::seed_from_u64(42); + let num_shots = 100_000; + let mut _correct = 0usize; + let mut total_errors = 0usize; + let mut unknown_syndromes = 0usize; + + for _ in 0..num_shots { + if let Some(dual) = sampler.sample_dual(&mut rng) { + let result = decoder.decode_from_bools(&dual.detector_events); + if !result.known_syndrome { + unknown_syndromes += 1; + } + + // Check: did the decoder's correction fix the logical? + // The actual DEM-output outcome is dual.dem_output_flips. + // After applying the correction, the residual should be identity. + let has_observable_error: bool = dual + .dem_output_flips + .iter() + .zip(&result.corrections) + .any(|(&flip, &corr)| flip ^ corr); // residual error + + if has_observable_error { + total_errors += 1; + } else { + _correct += 1; + } + } + } + + let error_rate = total_errors as f64 / num_shots as f64; + let raw_error_rate = sampler + .sample_statistics(num_shots, 42) + .logical_error_rate(); + + println!("\n Shots: {num_shots}"); + println!(" Unknown syndromes: {unknown_syndromes}"); + println!(" Raw observable rate: {raw_error_rate:.6}"); + println!(" Decoded error rate:{error_rate:.6}"); + println!( + " Improvement: {:.1}x", + raw_error_rate / error_rate.max(1e-10) + ); + + // The decoder should reduce the observable error rate compared to raw + // (for the repetition code with Z errors unprotected, improvement is modest + // since only X errors are correctable, but it should still help) + assert!( + total_errors < num_shots, + "Decoder should correct at least some errors" + ); +} + +/// Test decoder correctness: empty syndrome should produce no corrections. +#[test] +fn decoder_empty_syndrome() { + use pecos_qec::fault_tolerance::dem_builder::NoiseConfig; + use pecos_qec::fault_tolerance::lookup_decoder::LookupDecoder; + + let dag = build_repetition_code(1); + let noise = NoiseConfig::uniform(0.01); + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + let decoder = LookupDecoder::build(&map, &noise, 2); + + // Empty syndrome = no detectors fired = most likely no error + let result = decoder.decode(&[]); + assert!(result.known_syndrome, "Empty syndrome should be known"); + assert!( + result.corrections.iter().all(|&c| !c), + "Empty syndrome should produce no corrections: {:?}", + result.corrections + ); +} + +/// Test that the decoder table grows with weight, and truncation bound works. +#[test] +fn decoder_table_size_and_truncation() { + use pecos_qec::fault_tolerance::dem_builder::NoiseConfig; + use pecos_qec::fault_tolerance::lookup_decoder::LookupDecoder; + + let dag = build_repetition_code(1); + let noise = NoiseConfig::uniform(0.001); + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + let d1 = LookupDecoder::build(&map, &noise, 1); + let d2 = LookupDecoder::build(&map, &noise, 2); + let d3 = LookupDecoder::build(&map, &noise, 3); + + println!( + "Weight 1: {} syndromes, accounted={:.8}, truncation={:.2e}", + d1.num_syndromes(), + d1.accounted_probability(), + d1.truncation_bound() + ); + println!( + "Weight 2: {} syndromes, accounted={:.8}, truncation={:.2e}", + d2.num_syndromes(), + d2.accounted_probability(), + d2.truncation_bound() + ); + println!( + "Weight 3: {} syndromes, accounted={:.8}, truncation={:.2e}", + d3.num_syndromes(), + d3.accounted_probability(), + d3.truncation_bound() + ); + + // Higher weight covers more probability mass + assert!(d2.accounted_probability() >= d1.accounted_probability()); + assert!(d3.accounted_probability() >= d2.accounted_probability()); + + // At p=0.001, weight-3 should cover essentially all probability mass + assert!( + d3.truncation_bound() < 1e-6, + "Weight 3 at p=0.001 should have negligible truncation: {}", + d3.truncation_bound() + ); + + // Higher weight should discover at least as many syndromes + assert!(d2.num_syndromes() >= d1.num_syndromes()); + assert!(d1.num_syndromes() > 1); +} + +// ============================================================================ +// [[4,2,2]] Code Example +// ============================================================================ + +/// Build a [[4,2,2]] code circuit with `num_rounds` of syndrome extraction. +/// +/// The [[4,2,2]] code: +/// - 4 data qubits (0-3), 2 ancilla qubits (4-5) +/// - Stabilizers: `X_0` `X_1` `X_2` `X_3` and `Z_0` `Z_1` `Z_2` `Z_3` +/// - 2 logical qubits: +/// - Logical `Z_1` = `Z_0` `Z_1`, Logical `X_1` = `X_0` `X_2` +/// - Logical `Z_2` = `Z_0` `Z_2`, Logical `X_2` = `X_0` `X_1` +/// - Distance 2: detects any single-qubit error (cannot correct) +/// +/// X stabilizer measurement (ancilla 4): +/// Prep |+⟩, CX(ancilla, data) for each data qubit, H, MZ +/// +/// Z stabilizer measurement (ancilla 5): +/// Prep |0⟩, CX(data, ancilla) for each data qubit, MZ +fn build_422_code(num_rounds: usize) -> DagCircuit { + let mut dag = DagCircuit::new(); + + let data: Vec = vec![0, 1, 2, 3]; + let ancilla_x = 4; // measures X_0 X_1 X_2 X_3 + let ancilla_z = 5; // measures Z_0 Z_1 Z_2 Z_3 + + // Initialize data qubits + dag.pz(&data); + + let mut prev_meas_x = None; + let mut prev_meas_z = None; + + for round in 0..num_rounds { + // --- X stabilizer: X_0 X_1 X_2 X_3 --- + dag.pz(&[ancilla_x]); + dag.h(&[ancilla_x]); // prep |+⟩ + // CX(ancilla, data) propagates X from ancilla to data + dag.cx(&[ + (ancilla_x, data[0]), + (ancilla_x, data[1]), + (ancilla_x, data[2]), + (ancilla_x, data[3]), + ]); + dag.h(&[ancilla_x]); // rotate back to Z basis + let ms_x = dag.mz(&[ancilla_x]); + + // --- Z stabilizer: Z_0 Z_1 Z_2 Z_3 --- + dag.pz(&[ancilla_z]); + // CX(data, ancilla) propagates Z from data to ancilla + dag.cx(&[ + (data[0], ancilla_z), + (data[1], ancilla_z), + (data[2], ancilla_z), + (data[3], ancilla_z), + ]); + let ms_z = dag.mz(&[ancilla_z]); + + // Detectors + if round == 0 { + // Z stabilizer is deterministic on |0000⟩ (Z eigenstate) + dag.detector_labeled(&format!("Sz_r{round}"), &[ms_z[0]]); + // X stabilizer is NOT deterministic on |0000⟩ -- no standalone detector. + // First X measurement is a random coin flip; only round-to-round + // comparisons are valid detectors. + } else { + dag.detector_labeled(&format!("Sx_r{round}"), &[prev_meas_x.unwrap(), ms_x[0]]); + dag.detector_labeled(&format!("Sz_r{round}"), &[prev_meas_z.unwrap(), ms_z[0]]); + } + + prev_meas_x = Some(ms_x[0]); + prev_meas_z = Some(ms_z[0]); + } + + // Final data qubit measurements + let ms_data = dag.mz(&data); + + // Final detector: Z stabilizer from data should match last Z-ancilla. + // Z_0 Z_1 Z_2 Z_3 is readable from Z-basis data measurements. + dag.detector_labeled( + "Sz_final", + &[ + ms_data[0], + ms_data[1], + ms_data[2], + ms_data[3], + prev_meas_z.unwrap(), + ], + ); + // No final X-stabilizer detector: Z-basis data measurements cannot + // reconstruct X_0 X_1 X_2 X_3 parity. + + // Observables: logical Z readouts + // Logical Z_1 = Z_0 Z_1 + dag.observable_labeled("logical_Z1", &[ms_data[0], ms_data[1]]); + // Logical Z_2 = Z_0 Z_2 + dag.observable_labeled("logical_Z2", &[ms_data[0], ms_data[2]]); + + // Pauli operators: logical X operators + // Logical X_1 = X_0 X_2 + dag.pauli_operator_labeled("logical_X1", X(0) & X(2)); + // Logical X_2 = X_0 X_1 + dag.pauli_operator_labeled("logical_X2", X(0) & X(1)); + + dag +} + +#[test] +fn code_422_fault_enumeration() { + let dag = build_422_code(2); + + println!("[[4,2,2]] Code with 2 rounds"); + println!("Circuit: {} gates", dag.gate_count()); + println!("Annotations:"); + for ann in dag.annotations() { + let kind = match &ann.kind { + pecos_quantum::AnnotationKind::Detector { .. } => "detector", + pecos_quantum::AnnotationKind::Observable { .. } => "observable", + pecos_quantum::AnnotationKind::Operator => "operator", + }; + let label = ann.label.as_deref().unwrap_or("(none)"); + println!(" {kind:10} {label:15} {}", ann.pauli); + } + + // Build influence map + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + let locs = map.gate_fault_locations(); + println!( + "\nFault locations: {} (from {} per-qubit locations)", + locs.len(), + map.locations.len() + ); + println!( + "Detectors: {}, DEM outputs: {}", + map.detectors.len(), + map.influences.max_dem_output_index().map_or(0, |i| i + 1) + ); + + // Weight-1 + let mut w1_total = 0usize; + let mut w1_detectable = 0usize; + let mut w1_undetectable = 0usize; + let mut w1_trivial = 0usize; + + map.for_each_fault_combo(1, |combo| { + w1_total += 1; + let has_det = !combo.effect.detectors.is_empty(); + let has_dem_output = !combo.effect.dem_outputs.is_empty(); + match (has_det, has_dem_output) { + (true, _) => w1_detectable += 1, + (false, true) => { + w1_undetectable += 1; + if w1_undetectable <= 5 { + let c = &combo.components[0]; + let loc = &locs[c.location_index]; + let timing = if loc.before { "before" } else { "after" }; + println!( + " UNDET w=1: {} {timing} {:?} q={:?} -> dem_outputs={:?}", + c.event.pauli, + loc.gate_type, + loc.qubits + .iter() + .map(pecos_core::QubitId::index) + .collect::>(), + combo.effect.dem_outputs, + ); + } + } + (false, false) => w1_trivial += 1, + } + }); + + println!("\n--- Weight-1 faults ---"); + println!(" Total: {w1_total}"); + println!(" Detectable: {w1_detectable}"); + println!(" Undetectable: {w1_undetectable}"); + println!(" Trivial: {w1_trivial}"); + + // The [[4,2,2]] code starting from |0000⟩ has partial detection: + // - Z stabilizer detects X errors from round 1 (|0000⟩ is Z eigenstate) + // - X stabilizer only detects Z errors from round 2 onward (round-to-round) + // - First-round Z errors on data qubits are undetectable (no X-stabilizer + // detector in round 1, since |0000⟩ is not an X-stabilizer eigenstate) + assert!(w1_total > 0, "Should have fault events"); + assert!(w1_detectable > 0, "Some faults should be detectable"); + assert!(w1_undetectable > 0, "First-round Z faults are undetectable"); +} + +#[test] +fn code_422_ml_decoder() { + use pecos_qec::fault_tolerance::dem_builder::{DemSampler, NoiseConfig}; + use pecos_qec::fault_tolerance::lookup_decoder::LookupDecoder; + use rand::SeedableRng; + + let dag = build_422_code(2); + let noise = NoiseConfig::uniform(0.001); + + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + // Build ML decoder up to weight 2 + let decoder = LookupDecoder::build(&map, &noise, 2); + + println!("[[4,2,2]] ML Decoder:"); + println!(" Syndrome patterns: {}", decoder.num_syndromes()); + println!(" Observables: {}", decoder.num_observables()); + + // Build sampler + let sampler = DemSampler::from_circuit(&dag, noise).unwrap(); + + // Sample and decode + let mut rng = rand::rngs::SmallRng::seed_from_u64(42); + let num_shots = 100_000; + let mut decoded_errors = 0usize; + let mut raw_errors = 0usize; + + let mut post_selected_shots = 0usize; + let mut post_selected_errors = 0usize; + + for _ in 0..num_shots { + if let Some(dual) = sampler.sample_dual(&mut rng) { + let result = decoder.decode_from_bools(&dual.detector_events); + + // ML correction + let has_residual = dual + .dem_output_flips + .iter() + .zip(&result.corrections) + .any(|(&flip, &corr)| flip ^ corr); + + if has_residual { + decoded_errors += 1; + } + if dual.dem_output_flips.iter().any(|&f| f) { + raw_errors += 1; + } + + // Post-selection: only keep shots with no detectors fired + if !result.detected { + post_selected_shots += 1; + if dual.dem_output_flips.iter().any(|&f| f) { + post_selected_errors += 1; + } + } + } + } + + let raw_rate = raw_errors as f64 / num_shots as f64; + let decoded_rate = decoded_errors as f64 / num_shots as f64; + let ps_rate = if post_selected_shots > 0 { + post_selected_errors as f64 / post_selected_shots as f64 + } else { + 0.0 + }; + let discard_rate = 1.0 - post_selected_shots as f64 / num_shots as f64; + + println!("\n Shots: {num_shots}"); + println!(" Raw observable rate: {raw_rate:.6}"); + println!(" ML decoded rate: {decoded_rate:.6}"); + println!(" Post-selected rate: {ps_rate:.6} (discarded {discard_rate:.4})"); + println!( + " PS improvement: {:.1}x", + raw_rate / ps_rate.max(1e-10) + ); + + // For the [[4,2,2]] detection code, post-selection should improve the + // observable error rate: detected errors are discarded, only undetectable + // errors (weight 2+) remain. At p=0.001, this gives ~p^2 rate. + assert!( + ps_rate < raw_rate || post_selected_shots == 0, + "Post-selection should reduce observable error rate" + ); + assert!( + decoded_errors < num_shots, + "Some shots should decode correctly" + ); +} diff --git a/crates/pecos-qec/tests/targeted_tests.rs b/crates/pecos-qec/tests/targeted_tests.rs new file mode 100644 index 000000000..84b16df87 --- /dev/null +++ b/crates/pecos-qec/tests/targeted_tests.rs @@ -0,0 +1,330 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Targeted tests for specific features and bug fixes from the annotation/decoder session. + +use pecos_core::pauli::constructors::{X, Y, Z}; +use pecos_qec::fault_tolerance::InfluenceBuilder; +use pecos_qec::fault_tolerance::dem_builder::{NoiseConfig, PauliWeights}; +use pecos_qec::fault_tolerance::lookup_decoder::LookupDecoder; +use pecos_qec::fault_tolerance::propagator::{DagFaultAnalyzer, Pauli}; +use pecos_quantum::DagCircuit; + +// ============================================================================ +// Y anticommutation: Y commutes with Y +// ============================================================================ + +/// Verify that Y fault does NOT flip a detector when the propagated observable +/// is also Y on that qubit. {Y, Y} = 2I (commutes), not anticommutes. +#[test] +fn y_commutes_with_y() { + // Build a circuit where the backward-propagated observable has Y on a qubit. + // Backward propagation from MZ through H -> SZ -> H: + // MZ: Z -> backward H: X -> backward SZ: Y -> backward H: Y + // So at the first H location, the observable is Y on qubit 0. + let mut dag = DagCircuit::new(); + dag.pz(&[0]); + dag.h(&[0]); // observable is Y here (backward from MZ through H,SZ,H) + dag.sz(&[0]); // observable is X here (backward from MZ through H,SZ) + dag.h(&[0]); // observable is Z here (backward from MZ through H) + dag.mz(&[0]); + + let analyzer = DagFaultAnalyzer::new(&dag); + let map = analyzer.build_influence_map(); + + // Find the first H gate's after-location (node with lowest index) + // At this point the backward-propagated observable should have Y on qubit 0. + let h_locs: Vec<( + usize, + &pecos_qec::fault_tolerance::propagator::DagSpacetimeLocation, + )> = map + .locations + .iter() + .enumerate() + .filter(|(_, loc)| loc.gate_type == pecos_core::gate_type::GateType::H && !loc.before) + .collect(); + + assert!(h_locs.len() >= 2, "Should have at least 2 H locations"); + let (first_h_loc, _) = h_locs[0]; // first H (closest to prep) + + // Y fault at first H should NOT flip detector (Y commutes with Y) + let y_dets = map.get_detector_indices(first_h_loc, Pauli::Y as u8); + assert!( + y_dets.is_empty(), + "Y fault should not flip detectors when observable is Y on same qubit, got {y_dets:?}" + ); + // But X and Z faults SHOULD flip (both anticommute with Y) + let x_dets = map.get_detector_indices(first_h_loc, Pauli::X as u8); + let z_dets = map.get_detector_indices(first_h_loc, Pauli::Z as u8); + assert!( + !x_dets.is_empty() || !z_dets.is_empty(), + "X or Z fault should flip detectors when observable is Y" + ); +} + +// ============================================================================ +// T1/T2 idle noise +// ============================================================================ + +/// Verify T1/T2 produces biased noise: P(Z) > P(X) = P(Y). +#[test] +fn t1_t2_biased_idle_noise() { + let noise = NoiseConfig::new(0.001, 0.01, 0.001, 0.001).set_t1_t2(50_000.0, 30_000.0); + + // 1000 time units of idle + let pp = noise.idle_pauli_probs(1000.0); + + // P(X) == P(Y) (from amplitude damping) + assert!( + (pp.px - pp.py).abs() < 1e-15, + "P(X) should equal P(Y): px={}, py={}", + pp.px, + pp.py + ); + + // P(Z) > P(X) (dephasing dominates relaxation) + assert!( + pp.pz > pp.px, + "P(Z) should be larger than P(X): pz={}, px={}", + pp.pz, + pp.px + ); + + // Total should be reasonable (not > 1) + assert!(pp.total() < 1.0, "Total should be < 1: {}", pp.total()); + assert!(pp.total() > 0.0, "Total should be > 0"); +} + +/// Verify uniform depolarizing idle gives equal X/Y/Z. +#[test] +fn uniform_idle_noise() { + let noise = NoiseConfig::uniform(0.001); + let pp = noise.idle_pauli_probs(1.0); + + let eps = 1e-15; + assert!((pp.px - pp.py).abs() < eps); + assert!((pp.py - pp.pz).abs() < eps); + assert!((pp.px - 0.001 / 3.0).abs() < eps); +} + +// ============================================================================ +// PauliWeights +// ============================================================================ + +/// Verify custom single-qubit weights change decoder probabilities. +#[test] +fn custom_p1_weights_affect_decoder() { + let mut dag = DagCircuit::new(); + dag.pz(&[0, 1]); + dag.h(&[0]); + dag.cx(&[(0, 1)]); + let ms = dag.mz(&[0, 1]); + dag.observable(&[ms[0], ms[1]]); + + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + // Uniform weights + let noise_uniform = NoiseConfig::uniform(0.001); + let d_uniform = LookupDecoder::build(&map, &noise_uniform, 2); + + // Biased weights: Z only + let noise_biased = NoiseConfig::uniform(0.001).set_p1_weights(PauliWeights::from([ + (X(0), 0.0), + (Y(0), 0.0), + (Z(0), 1.0), + ])); + let d_biased = LookupDecoder::build(&map, &noise_biased, 2); + + // Both should build successfully + assert!(d_uniform.num_syndromes() > 0); + assert!(d_biased.num_syndromes() > 0); + + // Both should account for most probability at p=0.001 + assert!( + d_uniform.accounted_probability() > 0.99, + "Uniform: {}", + d_uniform.accounted_probability() + ); + assert!( + d_biased.accounted_probability() > 0.99, + "Biased: {}", + d_biased.accounted_probability() + ); +} + +/// Verify `PauliWeights` validates sum to ~1.0. +#[test] +#[should_panic(expected = "must sum to 1.0")] +fn pauli_weights_validation() { + // Should panic: doesn't sum to 1.0 + let _ = PauliWeights::from([(X(0), 0.5), (Y(0), 0.3)]); +} + +/// Verify `PauliWeights::weight_for` matches by pattern, not qubit ID. +#[test] +fn pauli_weights_pattern_matching() { + let w = PauliWeights::uniform_2q(); + + // X(0) & Z(1) pattern should match regardless of actual qubit IDs + let weight = w.weight_for(&(X(0) & Z(1))); + assert!((weight - 1.0 / 15.0).abs() < 1e-10); + + // Same pattern from different qubit IDs should also match + let weight2 = w.weight_for(&(X(5) & Z(9))); + assert!( + (weight2 - 1.0 / 15.0).abs() < 1e-10, + "Pattern matching should ignore qubit IDs: got {weight2}" + ); +} + +// ============================================================================ +// Prep-gate propagation stop +// ============================================================================ + +/// Verify that faults before a mid-circuit reset don't propagate past it. +#[test] +fn prep_gate_stops_propagation() { + // Circuit: PZ -> H -> PZ (reset) -> MZ + // An X fault after the first H should NOT affect the final measurement + // because the second PZ resets qubit 0. + let mut dag = DagCircuit::new(); + dag.pz(&[0]); + dag.h(&[0]); // fault here + dag.pz(&[0]); // mid-circuit reset -- should block propagation + dag.mz(&[0]); + + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + // Find the H gate's after-location + let mut h_has_influence = false; + for (loc_idx, loc) in map.locations.iter().enumerate() { + if loc.gate_type == pecos_core::gate_type::GateType::H && !loc.before { + let x_dets = map.influences.detectors(loc_idx, Pauli::X); + let z_dets = map.influences.detectors(loc_idx, Pauli::Z); + let y_dets = map.influences.detectors(loc_idx, Pauli::Y); + if !x_dets.is_empty() || !z_dets.is_empty() || !y_dets.is_empty() { + h_has_influence = true; + } + } + } + + assert!( + !h_has_influence, + "Faults before mid-circuit PZ should not propagate past the reset" + ); +} + +/// Verify that faults AFTER a mid-circuit reset DO affect later measurements. +#[test] +fn faults_after_reset_propagate() { + // Use DagFaultAnalyzer (which creates 1 detector per measurement) to + // verify that faults after a reset propagate to the measurement. + // Circuit: PZ -> PZ (reset) -> H -> MZ + let mut dag = DagCircuit::new(); + dag.pz(&[0]); + dag.pz(&[0]); // mid-circuit reset + dag.h(&[0]); // fault here should affect measurement + dag.mz(&[0]); + + let analyzer = DagFaultAnalyzer::new(&dag); + let map = analyzer.build_influence_map(); + + // H gate after-location should have detector influence + // (backward from MZ through H: observable is X at H location) + let mut h_has_influence = false; + for (loc_idx, loc) in map.locations.iter().enumerate() { + if loc.gate_type == pecos_core::gate_type::GateType::H && !loc.before { + for p in [Pauli::X, Pauli::Y, Pauli::Z] { + let dets = map.influences.detectors(loc_idx, p); + if !dets.is_empty() { + h_has_influence = true; + } + } + } + } + + assert!( + h_has_influence, + "Faults after mid-circuit PZ should propagate to later measurements" + ); +} + +// ============================================================================ +// DagCircuit annotation methods +// ============================================================================ + +/// Verify `detector()` auto-derives Z Pauli from measurement nodes. +#[test] +fn detector_derives_pauli_from_measurements() { + let mut dag = DagCircuit::new(); + dag.pz(&[0, 1]); + dag.cx(&[(0, 1)]); + let ms = dag.mz(&[0, 1]); + dag.detector(&[ms[0], ms[1]]); + + let ann = &dag.annotations()[0]; + // Pauli should be Z on both measured qubits + let paulis = ann.pauli.paulis(); + assert_eq!(paulis.len(), 2); + assert_eq!(paulis[0].0, pecos_core::Pauli::Z); + assert_eq!(paulis[1].0, pecos_core::Pauli::Z); +} + +/// Verify `pauli_operator` normalizes phase to +1. +#[test] +fn pauli_operator_normalizes_phase() { + let mut dag = DagCircuit::new(); + dag.pz(&[0]); + + // -X(0) has phase -1 + let neg_x = -X(0); + assert_ne!(neg_x.get_phase(), pecos_core::QuarterPhase::PlusOne); + + dag.pauli_operator(neg_x); + + // After storage, phase should be normalized to +1 + let ann = &dag.annotations()[0]; + assert_eq!(ann.pauli.get_phase(), pecos_core::QuarterPhase::PlusOne); +} + +/// Verify probability sums to 1.0 with the per-gate noise model. +#[test] +fn probability_sums_to_one() { + let mut dag = DagCircuit::new(); + dag.pz(&[0, 1]); + dag.h(&[0]); + dag.cx(&[(0, 1)]); + let ms = dag.mz(&[0, 1]); + dag.observable(&[ms[0], ms[1]]); + + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + let noise = NoiseConfig::uniform(0.001); + let decoder = LookupDecoder::build(&map, &noise, 3); + + assert!( + decoder.truncation_bound() < 1e-4, + "Weight-3 at p=0.001 should have small truncation: {}", + decoder.truncation_bound() + ); + assert!( + decoder.accounted_probability() > 0.999, + "Should account for >99.9% of probability: {}", + decoder.accounted_probability() + ); +} diff --git a/crates/pecos-qec/tests/unified_sampler_tests.rs b/crates/pecos-qec/tests/unified_sampler_tests.rs new file mode 100644 index 000000000..525e73cb9 --- /dev/null +++ b/crates/pecos-qec/tests/unified_sampler_tests.rs @@ -0,0 +1,483 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Verification tests for `DemSampler`. +//! +//! These tests ensure the `DemSampler` matches both: +//! 1. `DemSampler` output (detector-level) for the same seed +//! 2. raw measurement output (measurement-level) for the same seed +//! 3. Statistical equivalence across large shot counts + +use pecos_qec::fault_tolerance::InfluenceBuilder; +use pecos_qec::fault_tolerance::dem_builder::DemSamplerBuilder; +use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; +use pecos_quantum::DagCircuit; +use pecos_random::PecosRng; + +/// Build a repetition code syndrome extraction circuit with the given +/// number of rounds. Data qubits: 0, 1, 2. Ancilla qubits: 3, 4. +fn repetition_code_circuit(num_rounds: usize) -> DagCircuit { + let mut dag = DagCircuit::new(); + for _ in 0..num_rounds { + dag.pz(&[3]); + dag.pz(&[4]); + dag.cx(&[(0, 3)]); + dag.cx(&[(1, 3)]); + dag.cx(&[(1, 4)]); + dag.cx(&[(2, 4)]); + dag.mz(&[3]); + dag.mz(&[4]); + } + dag +} + +/// Build influence map with logical Z on all data qubits. +fn build_influence_map( + circuit: &DagCircuit, +) -> pecos_qec::fault_tolerance::propagator::DagFaultInfluenceMap { + InfluenceBuilder::new(circuit).with_z(&[0, 1, 2]).build() +} + +// ============================================================================ +// Test 1: DemSampler::from_influence_map matches DemSampler statistics +// ============================================================================ + +#[test] +fn from_influence_map_produces_reasonable_statistics() { + let circuit = repetition_code_circuit(3); + let influence_map = build_influence_map(&circuit); + let seed = 42u64; + let num_shots = 50_000; + + let sampler = DemSamplerBuilder::new(&influence_map) + .with_noise(0.001, 0.01, 0.005, 0.001) + .raw_measurements() + .build() + .unwrap(); + let stats = sampler.sample_statistics(num_shots, seed); + + // At these noise levels, we should see some syndromes. The builder above + // uses `with_z`, which creates a tracked operator, not an observable, so + // logical-error statistics and DEM output columns stay empty. + assert!( + stats.syndrome_rate() > 0.0, + "Should have some syndromes at p~0.001-0.01" + ); + assert!( + stats.syndrome_rate() < 1.0, + "Should not have syndromes on every shot" + ); + assert_eq!(sampler.num_observables(), 0); + assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!(stats.logical_error_count, 0); + assert!(stats.dem_output_counts().is_empty()); +} + +// ============================================================================ +// Test 2: MNM path produces valid measurement outcomes +// ============================================================================ + +#[test] +fn raw_sampler_produces_valid_measurement_outcomes() { + let circuit = repetition_code_circuit(2); + let influence_map = build_influence_map(&circuit); + + let sampler = DemSamplerBuilder::new(&influence_map) + .with_noise(0.001, 0.01, 0.005, 0.001) + .raw_measurements() + .build() + .unwrap(); + + let mut rng = PecosRng::seed_from_u64(42); + let (outcomes, _obs) = sampler.sample(&mut rng); + + assert_eq!(outcomes.len(), influence_map.measurements.len()); +} + +// ============================================================================ +// Test 3: Zero noise produces zero syndrome for both paths +// ============================================================================ + +#[test] +fn zero_noise_produces_zero_syndrome_both_paths() { + let circuit = repetition_code_circuit(3); + let influence_map = build_influence_map(&circuit); + + // DemSampler path + let sampler = DemSamplerBuilder::new(&influence_map) + .with_uniform_noise(0.0) + .raw_measurements() + .build() + .unwrap(); + let stats = sampler.sample_statistics(1000, 42); + assert_eq!( + stats.syndrome_count, 0, + "DemSampler: zero noise should give zero syndromes" + ); + assert_eq!( + stats.logical_error_count, 0, + "DemSampler: zero noise should give zero logical errors" + ); + + // DemSampler raw mode + let unified = DemSamplerBuilder::new(&influence_map) + .with_uniform_noise(0.0) + .raw_measurements() + .build() + .unwrap(); + let raw_stats = unified.sample_statistics(1000, 42); + assert_eq!( + raw_stats.syndrome_count, 0, + "Raw: zero noise should give zero syndromes" + ); +} + +// ============================================================================ +// Test 4: High noise produces high syndrome rate for both paths +// ============================================================================ + +#[test] +fn high_noise_produces_high_syndrome_rate_both_paths() { + let circuit = repetition_code_circuit(2); + let influence_map = build_influence_map(&circuit); + let num_shots = 10_000; + let p = 0.1; // 10% error rate — very noisy + + // DemSampler + let sampler = DemSamplerBuilder::new(&influence_map) + .with_uniform_noise(p) + .raw_measurements() + .build() + .unwrap(); + let stats = sampler.sample_statistics(num_shots, 42); + assert!( + stats.syndrome_rate() > 0.1, + "DemSampler: high noise should give high syndrome rate, got {}", + stats.syndrome_rate() + ); + + // DemSampler raw mode + let unified = DemSamplerBuilder::new(&influence_map) + .with_uniform_noise(p) + .raw_measurements() + .build() + .unwrap(); + let raw_stats = unified.sample_statistics(num_shots, 42); + assert!( + raw_stats.syndrome_rate() > 0.1, + "Raw: high noise should give high syndrome rate, got {}", + raw_stats.syndrome_rate() + ); +} + +// ============================================================================ +// Test 5: DemSampler detector mode matches DemSamplerBuilder statistics +// ============================================================================ + +#[test] +fn detector_mode_matches_dem_sampler_builder() { + let circuit = repetition_code_circuit(3); + let influence_map = build_influence_map(&circuit); + + let p1 = 0.001; + let p2 = 0.01; + let p_meas = 0.005; + let p_prep = 0.001; + let seed = 42u64; + let num_shots = 50_000; + + // Simple detector definitions: each measurement as its own detector + let num_meas = influence_map.measurements.len(); + let detector_records: Vec> = (0..num_meas) + .map(|i| vec![i32::try_from(i).unwrap()]) + .collect(); + let observable_records: Vec> = vec![]; + + // DemSamplerBuilder path + let dem_sampler = DemSamplerBuilder::new(&influence_map) + .with_noise(p1, p2, p_meas, p_prep) + .with_detector_records(detector_records.clone()) + .with_observable_records(observable_records.clone()) + .build() + .unwrap(); + let dem_stats = dem_sampler.sample_statistics(num_shots, seed); + + // DemSampler detector mode + let dem_sampler = DemSamplerBuilder::new(&influence_map) + .with_noise(p1, p2, p_meas, p_prep) + .with_detectors(detector_records, observable_records) + .build() + .unwrap(); + let raw_stats = dem_sampler.sample_statistics(num_shots, seed); + + // Same seed, same builder → identical statistics + assert_eq!( + dem_stats.total_shots, raw_stats.total_shots, + "Shot count mismatch" + ); + assert_eq!( + dem_stats.syndrome_count, raw_stats.syndrome_count, + "Syndrome count mismatch: DEM={}, Unified={}", + dem_stats.syndrome_count, raw_stats.syndrome_count + ); + assert_eq!( + dem_stats.logical_error_count, raw_stats.logical_error_count, + "Logical error count mismatch: DEM={}, Unified={}", + dem_stats.logical_error_count, raw_stats.logical_error_count + ); +} + +// ============================================================================ +// Test 6: DemSampler raw mode matches MNM measurement flip statistics +// ============================================================================ + +#[test] +fn raw_sampler_mode_matches_mnm_per_measurement() { + let circuit = repetition_code_circuit(2); + let influence_map = build_influence_map(&circuit); + + let p = 0.05; // moderate noise for visible statistics + let num_shots = 30_000; + + // DemSampler::from_influence_map path: count per-detector flips + let num_meas = influence_map.measurements.len(); + let dem = DemSamplerBuilder::new(&influence_map) + .with_uniform_noise(p) + .raw_measurements() + .build() + .unwrap(); + let mut dem_flip_counts = vec![0u64; num_meas]; + let mut rng = PecosRng::seed_from_u64(100); + for _ in 0..num_shots { + let (outcomes, _) = dem.sample(&mut rng); + for (i, &flipped) in outcomes.iter().enumerate() { + if flipped { + dem_flip_counts[i] += 1; + } + } + } + + // DemSampler raw mode: same exercise + let sampler = DemSamplerBuilder::new(&influence_map) + .with_uniform_noise(p) + .raw_measurements() + .build() + .unwrap(); + let mut unified_flip_counts = vec![0u64; num_meas]; + let mut rng2 = PecosRng::seed_from_u64(200); + for _ in 0..num_shots { + let (outputs, _) = sampler.sample(&mut rng2); + for (i, &flipped) in outputs.iter().enumerate() { + if flipped { + unified_flip_counts[i] += 1; + } + } + } + + // Compare per-measurement flip rates (different seeds -> statistical comparison) + for i in 0..num_meas { + // Flip counts are at most num_shots (30,000); precision loss is not a concern. + #[allow(clippy::cast_precision_loss)] + let dem_rate = dem_flip_counts[i] as f64 / f64::from(num_shots); + #[allow(clippy::cast_precision_loss)] + let unified_rate = unified_flip_counts[i] as f64 / f64::from(num_shots); + + // Allow generous tolerance since different seeds and non-det coin flips add noise + assert!( + (dem_rate - unified_rate).abs() < 0.1, + "Measurement {i} flip rate differs too much: DEM={dem_rate:.4}, Unified={unified_rate:.4}" + ); + } +} + +// ============================================================================ +// Test 7: DemSampler zero noise + detector mode = zero everything +// ============================================================================ + +#[test] +fn unified_zero_noise_detector_mode() { + let circuit = repetition_code_circuit(3); + let influence_map = build_influence_map(&circuit); + + let num_meas = influence_map.measurements.len(); + let detector_records: Vec> = (0..num_meas) + .map(|i| vec![i32::try_from(i).unwrap()]) + .collect(); + + let sampler = DemSamplerBuilder::new(&influence_map) + .with_uniform_noise(0.0) + .with_detectors(detector_records, vec![]) + .build() + .unwrap(); + + let stats = sampler.sample_statistics(1000, 42); + assert_eq!(stats.syndrome_count, 0); + assert_eq!(stats.logical_error_count, 0); +} + +// ============================================================================ +// Test 8: DemSampler batch output matches single-shot loop +// ============================================================================ + +#[test] +fn unified_batch_matches_single_shot_loop() { + let circuit = repetition_code_circuit(2); + let influence_map = build_influence_map(&circuit); + + let sampler = DemSamplerBuilder::new(&influence_map) + .with_uniform_noise(0.01) + .raw_measurements() + .build() + .unwrap(); + + let num_shots = 100; + let seed = 42u64; + + // Single-shot loop + let mut rng1 = PecosRng::seed_from_u64(seed); + let mut single_outputs = Vec::with_capacity(num_shots); + for _ in 0..num_shots { + let (out, _) = sampler.sample(&mut rng1); + single_outputs.push(out); + } + + // Batch + let mut rng2 = PecosRng::seed_from_u64(seed); + let (batch_outputs, _) = sampler.sample_batch(num_shots, &mut rng2); + + // Should match exactly (same seed, same engine) + // Note: non-det coin flips may differ between batch and single if + // the rng call order differs. This test verifies the mechanism-driven + // part matches. For measurements that are ALL deterministic (no non-det + // mask set), they should match exactly. + // For now, just check lengths match. + assert_eq!(single_outputs.len(), batch_outputs.len()); + assert_eq!(single_outputs[0].len(), batch_outputs[0].len()); +} + +// ============================================================================ +// Test 9: Linearly dependent detectors are rejected +// ============================================================================ + +#[test] +fn linearly_dependent_detectors_rejected() { + let circuit = repetition_code_circuit(2); + let influence_map = build_influence_map(&circuit); + + // Define 3 detectors where the third is XOR of the first two + // D0 = m[0], D1 = m[1], D2 = m[0] XOR m[1] = D0 XOR D1 → linearly dependent + let detector_records = vec![vec![0i32], vec![1], vec![0, 1]]; + let observable_records: Vec> = vec![]; + + let result = DemSamplerBuilder::new(&influence_map) + .with_noise(0.001, 0.01, 0.005, 0.001) + .with_detectors(detector_records, observable_records) + .build(); + + assert!( + result.is_err(), + "Should reject linearly dependent detector definitions" + ); + if let Err(e) = result { + let msg = format!("{e}"); + assert!( + msg.contains("linearly independent"), + "Error message should mention linear independence, got: {msg}" + ); + } +} + +// ============================================================================ +// Test 10: Valid independent detectors are accepted +// ============================================================================ + +#[test] +fn linearly_independent_detectors_accepted() { + let circuit = repetition_code_circuit(2); + let influence_map = build_influence_map(&circuit); + + // Two independent detectors: different single measurements + let detector_records = vec![vec![0i32], vec![1]]; + let observable_records: Vec> = vec![]; + + let result = DemSamplerBuilder::new(&influence_map) + .with_noise(0.001, 0.01, 0.005, 0.001) + .with_detectors(detector_records, observable_records) + .build(); + + assert!( + result.is_ok(), + "Should accept linearly independent detectors" + ); +} + +// ============================================================================ +// Test 11: In-circuit annotations → dual-output sampling +// ============================================================================ + +#[test] +fn circuit_annotation_dual_output() { + let mut dag = DagCircuit::new(); + + // 3 rounds for meaningful round-to-round detectors + let mut meas_nodes = Vec::new(); + for _ in 0..3 { + dag.pz(&[3, 4]); + dag.cx(&[(0, 3)]); + dag.cx(&[(1, 3)]); + dag.cx(&[(1, 4)]); + dag.cx(&[(2, 4)]); + let ms = dag.mz(&[3, 4]); + meas_nodes.push((ms[0].node, ms[1].node)); + } + + // Annotate round-to-round detectors (rounds 1-2 and 2-3) + dag.detector(&[meas_nodes[0].0, meas_nodes[1].0]); // q3 r1↔r2 + dag.detector(&[meas_nodes[0].1, meas_nodes[1].1]); // q4 r1↔r2 + dag.detector(&[meas_nodes[1].0, meas_nodes[2].0]); // q3 r2↔r3 + dag.detector(&[meas_nodes[1].1, meas_nodes[2].1]); // q4 r2↔r3 + + // Build MEASUREMENT-LEVEL influence map (DagFaultAnalyzer, not InfluenceBuilder) + // DagFaultAnalyzer creates one "detector" per raw measurement, so + // from_influence_map gives raw-measurement-level output suitable for + // user-defined detector XOR. + let analyzer = DagFaultAnalyzer::new(&dag); + let influence_map = analyzer.build_influence_map(); + + // Build sampler from annotations + let sampler = DemSamplerBuilder::new(&influence_map) + .with_uniform_noise(0.05) // high noise for visible effect + .with_circuit_annotations(&dag) + .build() + .unwrap(); + + assert!(sampler.num_mechanisms() > 0, "Should have mechanisms"); + + // Sample with dual output + let mut rng = PecosRng::seed_from_u64(42); + let mut det_fired = 0; + let num_shots = 10_000; + for _ in 0..num_shots { + if let Some(result) = sampler.sample_dual(&mut rng) + && result.detector_events.iter().any(|&d| d) + { + det_fired += 1; + } + } + + let rate = f64::from(det_fired) / f64::from(num_shots); + assert!(rate > 0.01, "Detectors should fire with p=0.05, got {rate}"); + assert!( + rate < 0.99, + "Detectors should not fire every shot, got {rate}" + ); +} diff --git a/crates/pecos-qis-ffi-types/src/lib.rs b/crates/pecos-qis-ffi-types/src/lib.rs index b7d30cb7c..31a0f2f84 100644 --- a/crates/pecos-qis-ffi-types/src/lib.rs +++ b/crates/pecos-qis-ffi-types/src/lib.rs @@ -5,12 +5,14 @@ //! //! The actual FFI implementation (with `#[no_mangle]` functions) is in `pecos-qis-ffi`. -use std::collections::BTreeMap; - mod operations; pub use operations::{Operation, QuantumOp}; +const DEFAULT_OPERATION_CAPACITY: usize = 1024; +const DEFAULT_MEASUREMENT_CAPACITY: usize = 256; +const DEFAULT_ID_CAPACITY: usize = 128; + /// Collection of quantum operations from program execution /// /// This struct is used to collect quantum operations during FFI execution. @@ -21,7 +23,7 @@ pub struct OperationCollector { pub operations: Vec, /// Mapping of measurement result IDs to their values (when known) - pub measurements: BTreeMap>, + pub measurements: Vec>, /// Allocated qubit IDs pub allocated_qubits: Vec, @@ -44,10 +46,10 @@ impl OperationCollector { #[must_use] pub fn new() -> Self { Self { - operations: Vec::new(), - measurements: BTreeMap::new(), - allocated_qubits: Vec::new(), - allocated_results: Vec::new(), + operations: Vec::with_capacity(DEFAULT_OPERATION_CAPACITY), + measurements: Vec::with_capacity(DEFAULT_MEASUREMENT_CAPACITY), + allocated_qubits: Vec::with_capacity(DEFAULT_ID_CAPACITY), + allocated_results: Vec::with_capacity(DEFAULT_ID_CAPACITY), next_qubit_id: 0, next_result_id: 0, } @@ -71,26 +73,41 @@ impl OperationCollector { let id = self.next_result_id; self.next_result_id += 1; self.allocated_results.push(id); - self.measurements.insert(id, None); + match self.measurements.len().cmp(&id) { + std::cmp::Ordering::Equal => self.measurements.push(None), + std::cmp::Ordering::Less => { + self.measurements.resize(id, None); + self.measurements.push(None); + } + std::cmp::Ordering::Greater => { + self.measurements[id] = None; + } + } id } /// Store a measurement result (used by runtime when results are available) pub fn store_result(&mut self, result_id: usize, value: bool) { - self.measurements.insert(result_id, Some(value)); + if self.measurements.len() <= result_id { + self.measurements.resize(result_id + 1, None); + } + self.measurements[result_id] = Some(value); } /// Get a measurement result (blocks until available in actual runtime) #[must_use] pub fn get_result(&self, result_id: usize) -> Option { - self.measurements.get(&result_id).and_then(|v| *v) + self.measurements.get(result_id).copied().flatten() } /// Pre-populate measurement results (for conditional execution) /// This allows setting measurement outcomes before program execution pub fn set_measurement_results(&mut self, results: impl IntoIterator) { for (result_id, value) in results { - self.measurements.insert(result_id, Some(value)); + if self.measurements.len() <= result_id { + self.measurements.resize(result_id + 1, None); + } + self.measurements[result_id] = Some(value); } } @@ -165,8 +182,8 @@ mod tests { assert_eq!(r1, 1); assert_eq!(collector.allocated_results, vec![0, 1]); // Results should be initialized to None - assert_eq!(collector.measurements.get(&0), Some(&None)); - assert_eq!(collector.measurements.get(&1), Some(&None)); + assert_eq!(collector.measurements.first(), Some(&None)); + assert_eq!(collector.measurements.get(1), Some(&None)); } #[test] diff --git a/crates/pecos-qis-ffi/src/ffi.rs b/crates/pecos-qis-ffi/src/ffi.rs index dc443bea6..a0188cea2 100644 --- a/crates/pecos-qis-ffi/src/ffi.rs +++ b/crates/pecos-qis-ffi/src/ffi.rs @@ -930,7 +930,7 @@ pub unsafe extern "C" fn pecos_qis_reset_interface() { crate::reset_interface(); } -/// Get a clone of the current `OperationCollector` +/// Take the current `OperationCollector`, leaving an empty collector behind. /// Exported as C function so it can be called via dlsym from the cdylib /// /// # Safety @@ -938,7 +938,7 @@ pub unsafe extern "C" fn pecos_qis_reset_interface() { /// `pecos_qis_free_operations` to avoid memory leaks. #[unsafe(no_mangle)] pub unsafe extern "C" fn pecos_qis_get_operations() -> *mut crate::OperationCollector { - let operations = with_interface(|interface| interface.clone()); + let operations = crate::take_interface(); Box::into_raw(Box::new(operations)) } @@ -1692,6 +1692,10 @@ mod tests { // Free unsafe { pecos_qis_free_operations(ptr) }; + + with_interface(|iface| { + assert!(iface.operations.is_empty()); + }); } #[test] diff --git a/crates/pecos-qis-ffi/src/lib.rs b/crates/pecos-qis-ffi/src/lib.rs index f4df3d223..5fecf0371 100644 --- a/crates/pecos-qis-ffi/src/lib.rs +++ b/crates/pecos-qis-ffi/src/lib.rs @@ -63,7 +63,7 @@ pub struct ExecutionContext { /// Storage for pending operations (shared between threads) pub pending_ops: Mutex>, /// Storage for measurement results (shared between threads) - pub measurement_results: Mutex>, + pub measurement_results: Mutex>>, /// Storage for named results from `print_bool`/`print_bool_arr` (e.g., "synx", "final") pub named_results: Mutex>>, } @@ -78,7 +78,7 @@ impl ExecutionContext { sync_state: Mutex::new(DynamicSyncState::default()), sync_condvar: Condvar::new(), pending_ops: Mutex::new(Vec::new()), - measurement_results: Mutex::new(BTreeMap::new()), + measurement_results: Mutex::new(Vec::new()), named_results: Mutex::new(BTreeMap::new()), } } @@ -247,6 +247,12 @@ pub fn get_interface_clone() -> OperationCollector { with_interface(|interface| interface.clone()) } +/// Take the thread-local operation collector, leaving an empty collector behind. +#[must_use] +pub fn take_interface() -> OperationCollector { + with_interface(std::mem::take) +} + /// Set measurement results in the thread-local operation collector pub fn set_measurements(measurements: impl IntoIterator) { with_interface(|interface| interface.set_measurement_results(measurements)); @@ -506,13 +512,17 @@ pub fn wait_for_result_ready(result_id: u64, timeout_ms: u64) -> bool { // SAFETY: Context is valid for duration of execution let ctx = unsafe { &*ctx }; - // Export pending operations to context storage before blocking - // This allows the main thread to access them + // Move all operations accumulated since the previous handoff into the + // shared pending buffer. In dynamic mode the thread-local operations vec + // is treated as an unsent queue, so this avoids cloning the fresh segment. INTERFACE.with(|interface| { - let iface = interface.borrow(); + let mut iface = interface.borrow_mut(); if let Ok(mut pending) = ctx.pending_ops.lock() { - pending.clear(); - pending.extend(iface.operations.iter().cloned()); + if pending.is_empty() { + std::mem::swap(&mut *pending, &mut iface.operations); + } else if !iface.operations.is_empty() { + pending.append(&mut iface.operations); + } log::debug!( "wait_for_result_ready: exported {} pending operations", pending.len() @@ -567,10 +577,11 @@ pub fn is_dynamic_mode_active() -> bool { #[must_use] pub fn get_measurement_result(result_id: u64) -> Option { let ctx = get_execution_context()?; + let result_index = usize::try_from(result_id).ok()?; // SAFETY: Context is valid for duration of execution let ctx = unsafe { &*ctx }; if let Ok(results) = ctx.measurement_results.lock() { - let value = results.get(&result_id).copied(); + let value = results.get(result_index).copied().flatten(); log::debug!("get_measurement_result: result_id={result_id}, value={value:?}"); value } else { @@ -589,10 +600,17 @@ pub fn get_measurement_result(result_id: u64) -> Option { pub extern "C" fn pecos_set_measurement_result(result_id: u64, value: bool) { log::debug!("pecos_set_measurement_result: result_id={result_id}, value={value}"); if let Some(ctx) = get_execution_context() { + let Ok(result_index) = usize::try_from(result_id) else { + log::warn!("pecos_set_measurement_result: result_id {result_id} does not fit in usize"); + return; + }; // SAFETY: Context is valid for duration of execution let ctx = unsafe { &*ctx }; if let Ok(mut results) = ctx.measurement_results.lock() { - results.insert(result_id, value); + if results.len() <= result_index { + results.resize(result_index + 1, None); + } + results[result_index] = Some(value); } } else { log::warn!("pecos_set_measurement_result: no execution context registered"); @@ -629,9 +647,9 @@ pub extern "C" fn pecos_get_pending_operations() -> *mut OperationCollector { let ctx = unsafe { &*ctx }; let ops = match ctx.pending_ops.lock() { - Ok(pending) => { + Ok(mut pending) => { log::debug!("pecos_get_pending_operations: {} operations", pending.len()); - pending.clone() + std::mem::take(&mut *pending) } Err(_) => return std::ptr::null_mut(), }; @@ -784,7 +802,8 @@ mod tests { context.dynamic_mode_active.store(true, Ordering::SeqCst); context.waiting_for_result.store(42, Ordering::SeqCst); if let Ok(mut results) = context.measurement_results.lock() { - results.insert(0, true); + results.resize(1, None); + results[0] = Some(true); } if let Ok(mut ops) = context.pending_ops.lock() { ops.push(Operation::AllocateQubit { id: 0 }); @@ -975,7 +994,7 @@ mod tests { worker_barrier.wait(); // Wait for the result (with timeout) - let timeout = Duration::from_millis(1000); + let timeout = Duration::from_secs(1); let mut state = context.sync_state.lock().unwrap(); while !state.result_ready { let result = context.sync_condvar.wait_timeout(state, timeout).unwrap(); @@ -1036,6 +1055,10 @@ mod tests { // Free the collector unsafe { pecos_free_operations(ptr) }; + // Second read should be empty because the handoff drains pending ops. + let ptr = pecos_get_pending_operations(); + assert!(ptr.is_null()); + teardown_context(ctx); } @@ -1336,6 +1359,76 @@ mod tests { } } + #[test] + fn test_wait_for_result_ready_exports_only_new_operations() { + use std::sync::Barrier; + + let ctx = pecos_create_execution_context(); + let ctx_ptr = ctx as usize; + + unsafe { pecos_register_execution_context(ctx) }; + pecos_enable_dynamic_mode(); + + let barrier = Arc::new(Barrier::new(2)); + let worker_barrier = Arc::clone(&barrier); + + let worker = thread::spawn(move || { + let ctx = ctx_ptr as *mut ExecutionContext; + unsafe { pecos_register_execution_context(ctx) }; + + with_interface(|iface| { + iface.queue_operation(Operation::AllocateQubit { id: 0 }); + }); + + worker_barrier.wait(); + + assert!(wait_for_result_ready(0, 500)); + + with_interface(|iface| { + assert!(iface.operations.is_empty()); + }); + + with_interface(|iface| { + iface.queue_operation(Operation::Quantum(QuantumOp::H(0))); + }); + + assert!(wait_for_result_ready(1, 500)); + + with_interface(|iface| { + assert!(iface.operations.is_empty()); + }); + + unsafe { pecos_register_execution_context(std::ptr::null_mut()) }; + }); + + barrier.wait(); + + let needed_id = pecos_wait_for_need_result(500); + assert_eq!(needed_id, 0); + let ops_ptr = pecos_get_pending_operations(); + assert!(!ops_ptr.is_null()); + let ops = unsafe { &*ops_ptr }; + assert_eq!(ops.operations, vec![Operation::AllocateQubit { id: 0 }]); + unsafe { pecos_free_operations(ops_ptr) }; + pecos_signal_result_ready(); + + let needed_id = pecos_wait_for_need_result(500); + assert_eq!(needed_id, 1); + let ops_ptr = pecos_get_pending_operations(); + assert!(!ops_ptr.is_null()); + let ops = unsafe { &*ops_ptr }; + assert_eq!(ops.operations, vec![Operation::Quantum(QuantumOp::H(0))]); + unsafe { pecos_free_operations(ops_ptr) }; + pecos_signal_result_ready(); + + worker.join().unwrap(); + + unsafe { + pecos_register_execution_context(std::ptr::null_mut()); + pecos_destroy_execution_context(ctx); + } + } + #[test] fn test_is_dynamic_mode_active() { let ctx = setup_context(); diff --git a/crates/pecos-qis/Cargo.toml b/crates/pecos-qis/Cargo.toml index c974f4965..f45a9b899 100644 --- a/crates/pecos-qis/Cargo.toml +++ b/crates/pecos-qis/Cargo.toml @@ -47,6 +47,7 @@ log.workspace = true dyn-clone.workspace = true tempfile.workspace = true rand.workspace = true +serde = { workspace = true, features = ["derive"] } serde_json.workspace = true crossbeam-channel.workspace = true libloading.workspace = true diff --git a/crates/pecos-qis/src/ccengine.rs b/crates/pecos-qis/src/ccengine.rs index f78ec3e88..5c85fe079 100644 --- a/crates/pecos-qis/src/ccengine.rs +++ b/crates/pecos-qis/src/ccengine.rs @@ -15,7 +15,7 @@ use crate::program::QisInterfaceBuilder; use crate::qis_interface::{BoxedInterface, DynamicSyncHandle, ProgramFormat}; use crate::runtime::QisRuntime; -use log::debug; +use log::{debug, warn}; use pecos_core::Angle64; use pecos_core::prelude::PecosError; use pecos_engines::noise::utils::NoiseUtils; @@ -25,11 +25,44 @@ use pecos_engines::{ }; use pecos_qis_ffi_types::{Operation, OperationCollector as OperationList, QuantumOp}; use pecos_random::PecosRng; -use std::collections::BTreeMap; -use std::sync::Mutex; +use std::collections::{BTreeMap, BTreeSet}; +use std::fs; +use std::path::PathBuf; +use std::sync::atomic::{AtomicU64, Ordering}; use std::sync::mpsc::{self, Receiver, Sender}; +use std::sync::{Arc, Mutex}; use std::thread::JoinHandle; +static TRACE_ENGINE_ID_COUNTER: AtomicU64 = AtomicU64::new(1); + +/// One lowered quantum gate in a traced batch. +#[derive(Debug, Clone, serde::Serialize)] +pub struct LoweredQuantumGateTrace { + pub gate_type: String, + pub angles: Vec, + pub params: Vec, + pub qubits: Vec, +} + +/// One traced batch of QIS operations and their lowered simulator commands. +#[derive(Debug, Clone, serde::Serialize)] +pub struct OperationTraceChunk { + pub format: &'static str, + pub engine_trace_id: u64, + pub shot_index: usize, + pub chunk_index: usize, + pub stage: String, + pub waiting_for_result_id: Option, + pub current_shot_seed: Option, + pub simulated_op_count: usize, + pub num_operations: usize, + pub operations: Vec, + pub lowered_quantum_ops: Vec, +} + +/// Shared in-memory store for traced QIS operation batches. +pub type OperationTraceStore = Arc>>; + /// Result from worker thread - returns both the operations and the interface type WorkerResult = Result<(OperationList, BoxedInterface), String>; @@ -155,8 +188,29 @@ pub struct QisEngine { /// Current operations collected from the interface current_operations: Option, - /// Number of qubits in the program - num_qubits: usize, + /// High-water mark of physical simulator slots allocated across the current shot. + /// + /// Equals `max(slot_index) + 1` over every slot ever activated by + /// `allocate_qubit_slot`. Because `allocate_qubit_slot` refills freed slots + /// before extending the range, this is also the minimum number of simulator + /// slots that must exist to execute the program. Not the count of program + /// qubit handles — use `active_qubit_slots.len()` for that. + num_physical_slots: usize, + + /// Mapping from program-level qubit handles to physical simulator slots. + active_qubit_slots: BTreeMap, + + /// Reusable physical simulator slots freed by `ReleaseQubit`. + free_qubit_slots: BTreeSet, + + /// Program-level qubit handles seen during the current shot. + /// + /// Some QIS interfaces model initial/static qubits via `allocated_qubits` + /// metadata instead of explicit `AllocateQubit` operations. We accept a + /// first use of such a handle and lazily materialize a simulator slot, but + /// still reject a later use-after-release unless a new `AllocateQubit` + /// arrives. + seen_program_qubits: BTreeSet, /// Whether we've started processing started: bool, @@ -194,9 +248,66 @@ pub struct QisEngine { /// Persistent worker thread for dynamic execution (stays alive across shots) /// This avoids spawning a new thread per shot, which causes TLS allocation issues. persistent_worker: Option, + + /// Directory where operation trace chunks are dumped as JSON. + operation_trace_dir: Option, + + /// Optional in-memory collector for traced chunks. + operation_trace_collector: Option, + + /// Unique trace id for this engine instance. + trace_engine_id: u64, + + /// 1-based shot index for operation traces. + trace_shot_index: usize, + + /// 0-based chunk index within the current shot. + trace_chunk_index: usize, + + /// Scratch builder reused when materializing command batches. + command_builder: ByteMessageBuilder, } impl QisEngine { + fn parse_measurement_outcomes(message: &ByteMessage) -> Result, PecosError> { + message + .outcomes() + .map(|outcomes| outcomes.into_iter().map(|value| value as usize).collect()) + .map_err(|e| PecosError::Generic(format!("Failed to parse measurements: {e}"))) + } + + fn map_measurements( + measurement_mapping: &[usize], + measurements: &[usize], + ) -> Vec<(usize, bool)> { + measurement_mapping + .iter() + .copied() + .zip(measurements.iter().copied()) + .map(|(result_id, value)| (result_id, value != 0)) + .collect() + } + + fn store_measurement_updates(&mut self, updates: &[(usize, bool)]) { + for &(result_id, value) in updates { + self.measurement_results.insert(result_id, value); + debug!("QisEngine: Stored measurement result_id={result_id}, value={value}"); + } + } + + fn provide_measurement_updates_to_runtime( + &mut self, + updates: &[(usize, bool)], + ) -> Result<(), PecosError> { + if updates.is_empty() { + return Ok(()); + } + let measurement_map: BTreeMap = updates.iter().copied().collect(); + self.runtime + .provide_measurements(measurement_map) + .map_err(|e| PecosError::Generic(format!("Failed to provide measurements: {e}"))) + } + /// Create a new engine with the given interface and runtime /// /// Dynamic execution is always enabled - all LLVM runs on a worker thread. @@ -208,7 +319,10 @@ impl QisEngine { interface: Some(interface), runtime, current_operations: None, - num_qubits: 0, + num_physical_slots: 0, + active_qubit_slots: BTreeMap::new(), + free_qubit_slots: BTreeSet::new(), + seen_program_qubits: BTreeSet::new(), started: false, measurement_mapping: Vec::new(), measurement_results: BTreeMap::new(), @@ -221,6 +335,12 @@ impl QisEngine { program_format: None, interface_builder: None, persistent_worker: None, + operation_trace_dir: None, + operation_trace_collector: None, + trace_engine_id: TRACE_ENGINE_ID_COUNTER.fetch_add(1, Ordering::Relaxed), + trace_shot_index: 0, + trace_chunk_index: 0, + command_builder: ByteMessageBuilder::new(), } } @@ -251,6 +371,16 @@ impl QisEngine { self.program_format = Some(ProgramFormat::LlvmIrText); } + /// Configure a directory where Helios-collected operation chunks are written as JSON. + pub fn set_operation_trace_dir(&mut self, trace_dir: impl Into) { + self.operation_trace_dir = Some(trace_dir.into()); + } + + /// Configure an in-memory collector that receives traced operation chunks. + pub fn set_operation_trace_collector(&mut self, collector: OperationTraceStore) { + self.operation_trace_collector = Some(collector); + } + /// Initialize the engine for dynamic execution /// /// This verifies the interface supports dynamic execution and defers @@ -281,7 +411,10 @@ impl QisEngine { interface: None, runtime, current_operations: None, - num_qubits: 0, + num_physical_slots: 0, + active_qubit_slots: BTreeMap::new(), + free_qubit_slots: BTreeSet::new(), + seen_program_qubits: BTreeSet::new(), started: false, measurement_mapping: Vec::new(), measurement_results: BTreeMap::new(), @@ -294,6 +427,12 @@ impl QisEngine { program_format: None, interface_builder: None, persistent_worker: None, + operation_trace_dir: None, + operation_trace_collector: None, + trace_engine_id: TRACE_ENGINE_ID_COUNTER.fetch_add(1, Ordering::Relaxed), + trace_shot_index: 0, + trace_chunk_index: 0, + command_builder: ByteMessageBuilder::new(), } } @@ -341,84 +480,254 @@ impl QisEngine { } } - /// Convert quantum operations to `ByteMessage` for the quantum engine - fn operations_to_bytemessage( + fn reset_qubit_slots(&mut self) { + self.active_qubit_slots.clear(); + self.free_qubit_slots.clear(); + self.seen_program_qubits.clear(); + self.num_physical_slots = 0; + } + + fn allocate_qubit_slot(&mut self, program_id: usize) -> usize { + if let Some(&slot) = self.active_qubit_slots.get(&program_id) { + return slot; + } + + let slot = if let Some(slot) = self.free_qubit_slots.pop_first() { + slot + } else { + self.num_physical_slots + }; + self.num_physical_slots = self.num_physical_slots.max(slot + 1); + self.active_qubit_slots.insert(program_id, slot); + self.seen_program_qubits.insert(program_id); + slot + } + + fn release_qubit_slot(&mut self, program_id: usize) { + if let Some(slot) = self.active_qubit_slots.remove(&program_id) { + self.free_qubit_slots.insert(slot); + } + } + + fn mapped_qubit(&mut self, program_id: usize, op: &QuantumOp) -> Result { + if let Some(&slot) = self.active_qubit_slots.get(&program_id) { + return Ok(slot); + } + + if self.seen_program_qubits.contains(&program_id) { + return Err(PecosError::Generic(format!( + "QIS runtime emitted {op:?} for program qubit {program_id}, but that handle is not currently active; it was likely released without a matching re-allocation" + ))); + } + + Ok(self.allocate_qubit_slot(program_id)) + } + + /// Convert dynamic QIS operations into a `ByteMessage` for the quantum engine. + /// + /// Guppy and the LLVM/QIS path allocate fresh qubit handles over time, even when + /// the source program is reusing ancillas logically. The quantum simulators used + /// by `sim()` operate on a fixed physical qubit pool, so we must honor + /// `AllocateQubit`/`ReleaseQubit` and remap program handles back onto reusable + /// physical slots before sending the quantum ops downstream. + fn operations_to_bytemessage(&mut self, ops: &[Operation]) -> Result { + let mut builder = std::mem::take(&mut self.command_builder); + builder.reset(); + self.measurement_mapping.clear(); + + let result = (|| -> Result<(), PecosError> { + for op in ops { + match op { + Operation::AllocateQubit { id } => { + let slot = self.allocate_qubit_slot(*id); + builder.pz(&[slot]); + } + Operation::ReleaseQubit { id } => { + self.release_qubit_slot(*id); + } + Operation::AllocateResult { .. } + | Operation::RecordOutput { .. } + | Operation::Barrier => {} + Operation::Quantum(qop) => match qop { + QuantumOp::H(qubit) => { + builder.h(&[self.mapped_qubit(*qubit, qop)?]); + } + QuantumOp::X(qubit) => { + builder.x(&[self.mapped_qubit(*qubit, qop)?]); + } + QuantumOp::Y(qubit) => { + builder.y(&[self.mapped_qubit(*qubit, qop)?]); + } + QuantumOp::Z(qubit) => { + builder.z(&[self.mapped_qubit(*qubit, qop)?]); + } + QuantumOp::S(qubit) => { + builder.sz(&[self.mapped_qubit(*qubit, qop)?]); + } + QuantumOp::Sdg(qubit) => { + builder.szdg(&[self.mapped_qubit(*qubit, qop)?]); + } + QuantumOp::T(qubit) => { + builder.t(&[self.mapped_qubit(*qubit, qop)?]); + } + QuantumOp::Tdg(qubit) => { + builder.tdg(&[self.mapped_qubit(*qubit, qop)?]); + } + QuantumOp::RX(angle, qubit) => { + builder.rx( + Angle64::from_radians(*angle), + &[self.mapped_qubit(*qubit, qop)?], + ); + } + QuantumOp::RY(angle, qubit) => { + builder.ry( + Angle64::from_radians(*angle), + &[self.mapped_qubit(*qubit, qop)?], + ); + } + QuantumOp::RZ(angle, qubit) => { + builder.rz( + Angle64::from_radians(*angle), + &[self.mapped_qubit(*qubit, qop)?], + ); + } + QuantumOp::RXY(theta, phi, qubit) => { + builder.r1xy( + Angle64::from_radians(*theta), + Angle64::from_radians(*phi), + &[self.mapped_qubit(*qubit, qop)?], + ); + } + QuantumOp::CX(control, target) => { + builder.cx(&[( + self.mapped_qubit(*control, qop)?, + self.mapped_qubit(*target, qop)?, + )]); + } + QuantumOp::Measure(qubit, result_id) => { + self.measurement_mapping.push(*result_id); + builder.mz(&[self.mapped_qubit(*qubit, qop)?]); + } + QuantumOp::ZZ(qubit1, qubit2) => { + builder.szz(&[( + self.mapped_qubit(*qubit1, qop)?, + self.mapped_qubit(*qubit2, qop)?, + )]); + } + QuantumOp::RZZ(angle, qubit1, qubit2) => { + builder.rzz( + Angle64::from_radians(*angle), + &[( + self.mapped_qubit(*qubit1, qop)?, + self.mapped_qubit(*qubit2, qop)?, + )], + ); + } + QuantumOp::Reset(qubit) => { + builder.pz(&[self.mapped_qubit(*qubit, qop)?]); + } + _ => { + return Err(PecosError::Generic(format!( + "Unsupported operation: {qop:?}" + ))); + } + }, + } + } + + Ok(()) + })(); + + let message = result.map(|()| builder.build()); + self.command_builder = builder; + message + } + + /// Convert already-materialized quantum ops into a `ByteMessage`. + /// + /// This path is used by runtimes that already present qubit ids in the fixed + /// simulator space, so no allocate/release remapping is needed. + fn quantum_ops_to_bytemessage( &mut self, ops: Vec, ) -> Result { - let mut builder = ByteMessageBuilder::new(); + let mut builder = std::mem::take(&mut self.command_builder); + builder.reset(); self.measurement_mapping.clear(); - for op in ops { - match op { - QuantumOp::H(qubit) => { - builder.h(&[qubit]); - } - QuantumOp::X(qubit) => { - builder.x(&[qubit]); - } - QuantumOp::Y(qubit) => { - builder.y(&[qubit]); - } - QuantumOp::Z(qubit) => { - builder.z(&[qubit]); - } - QuantumOp::S(qubit) => { - builder.sz(&[qubit]); - } - QuantumOp::Sdg(qubit) => { - builder.szdg(&[qubit]); - } - QuantumOp::T(qubit) => { - builder.t(&[qubit]); - } - QuantumOp::Tdg(qubit) => { - builder.tdg(&[qubit]); - } - QuantumOp::RX(angle, qubit) => { - builder.rx(Angle64::from_radians(angle), &[qubit]); - } - QuantumOp::RY(angle, qubit) => { - builder.ry(Angle64::from_radians(angle), &[qubit]); - } - QuantumOp::RZ(angle, qubit) => { - builder.rz(Angle64::from_radians(angle), &[qubit]); - } - QuantumOp::RXY(theta, phi, qubit) => { - builder.r1xy( - Angle64::from_radians(theta), - Angle64::from_radians(phi), - &[qubit], - ); - } - QuantumOp::CX(control, target) => { - builder.cx(&[(control, target)]); - } - QuantumOp::Measure(qubit, result_id) => { - self.measurement_mapping.push(result_id); - builder.mz(&[qubit]); - } - QuantumOp::ZZ(qubit1, qubit2) => { - // ZZ gate is the same as SZZ in PECOS - builder.szz(&[(qubit1, qubit2)]); - } - QuantumOp::RZZ(angle, qubit1, qubit2) => { - builder.rzz(Angle64::from_radians(angle), &[(qubit1, qubit2)]); - } - QuantumOp::Reset(qubit) => { - builder.pz(&[qubit]); - } - _ => { - // For other operations, we'd need to add more builder methods - // or convert to a generic gate representation - return Err(PecosError::Generic(format!( - "Unsupported operation: {op:?}" - ))); + let result = (|| -> Result<(), PecosError> { + for op in ops { + match op { + QuantumOp::H(qubit) => { + builder.h(&[qubit]); + } + QuantumOp::X(qubit) => { + builder.x(&[qubit]); + } + QuantumOp::Y(qubit) => { + builder.y(&[qubit]); + } + QuantumOp::Z(qubit) => { + builder.z(&[qubit]); + } + QuantumOp::S(qubit) => { + builder.sz(&[qubit]); + } + QuantumOp::Sdg(qubit) => { + builder.szdg(&[qubit]); + } + QuantumOp::T(qubit) => { + builder.t(&[qubit]); + } + QuantumOp::Tdg(qubit) => { + builder.tdg(&[qubit]); + } + QuantumOp::RX(angle, qubit) => { + builder.rx(Angle64::from_radians(angle), &[qubit]); + } + QuantumOp::RY(angle, qubit) => { + builder.ry(Angle64::from_radians(angle), &[qubit]); + } + QuantumOp::RZ(angle, qubit) => { + builder.rz(Angle64::from_radians(angle), &[qubit]); + } + QuantumOp::RXY(theta, phi, qubit) => { + builder.r1xy( + Angle64::from_radians(theta), + Angle64::from_radians(phi), + &[qubit], + ); + } + QuantumOp::CX(control, target) => { + builder.cx(&[(control, target)]); + } + QuantumOp::Measure(qubit, result_id) => { + self.measurement_mapping.push(result_id); + builder.mz(&[qubit]); + } + QuantumOp::ZZ(qubit1, qubit2) => { + builder.szz(&[(qubit1, qubit2)]); + } + QuantumOp::RZZ(angle, qubit1, qubit2) => { + builder.rzz(Angle64::from_radians(angle), &[(qubit1, qubit2)]); + } + QuantumOp::Reset(qubit) => { + builder.pz(&[qubit]); + } + _ => { + return Err(PecosError::Generic(format!( + "Unsupported operation: {op:?}" + ))); + } } } - } - Ok(builder.build()) + Ok(()) + })(); + + let message = result.map(|()| builder.build()); + self.command_builder = builder; + message } } @@ -450,7 +759,10 @@ impl Clone for QisEngine { interface, runtime: dyn_clone::clone_box(&*self.runtime), current_operations: self.current_operations.clone(), - num_qubits: self.num_qubits, + num_physical_slots: self.num_physical_slots, + active_qubit_slots: self.active_qubit_slots.clone(), + free_qubit_slots: self.free_qubit_slots.clone(), + seen_program_qubits: self.seen_program_qubits.clone(), started: false, // Reset started flag for the clone measurement_mapping: Vec::new(), // Clear for new shot measurement_results: BTreeMap::new(), // Clear for new shot @@ -467,12 +779,126 @@ impl Clone for QisEngine { .map(|b| dyn_clone::clone_box(&**b)), // Create a new persistent worker for this clone (can't share threads across clones) persistent_worker: None, + operation_trace_dir: self.operation_trace_dir.clone(), + operation_trace_collector: self.operation_trace_collector.clone(), + trace_engine_id: TRACE_ENGINE_ID_COUNTER.fetch_add(1, Ordering::Relaxed), + trace_shot_index: 0, + trace_chunk_index: 0, + command_builder: ByteMessageBuilder::new(), } } } // Helper methods for dynamic execution impl QisEngine { + fn begin_trace_shot(&mut self) { + self.trace_shot_index = self + .trace_shot_index + .checked_add(1) + .expect("trace_shot_index overflow: too many shots for a single trace engine"); + self.trace_chunk_index = 0; + } + + fn lowered_quantum_ops_trace(commands: &ByteMessage) -> Vec { + match commands.quantum_ops() { + Ok(gates) => gates + .iter() + .map(|gate| LoweredQuantumGateTrace { + gate_type: gate.gate_type.to_string(), + angles: gate + .angles + .iter() + .map(Angle64::to_radians) + .collect::>(), + params: gate.params.iter().copied().collect::>(), + qubits: gate + .qubits + .iter() + .map(|q| usize::from(*q)) + .collect::>(), + }) + .collect::>(), + Err(err) => { + warn!("Failed to parse lowered quantum ops for tracing: {err}"); + Vec::new() + } + } + } + + fn trace_operations_chunk( + &mut self, + stage: &str, + ops: &[Operation], + waiting_for_result_id: Option, + lowered_quantum_ops: Option<&ByteMessage>, + ) { + if self.operation_trace_dir.is_none() && self.operation_trace_collector.is_none() { + return; + } + + let lowered_trace = lowered_quantum_ops + .map(Self::lowered_quantum_ops_trace) + .unwrap_or_default(); + let file_name = format!( + "engine_{:04}_shot_{:06}_chunk_{:04}_{}.json", + self.trace_engine_id, self.trace_shot_index, self.trace_chunk_index, stage + ); + let chunk_index = self.trace_chunk_index; + self.trace_chunk_index = self + .trace_chunk_index + .checked_add(1) + .expect("trace_chunk_index overflow: too many chunks for a single trace shot"); + let chunk = OperationTraceChunk { + format: "pecos_qis_operation_trace_v1", + engine_trace_id: self.trace_engine_id, + shot_index: self.trace_shot_index, + chunk_index, + stage: stage.to_string(), + waiting_for_result_id, + current_shot_seed: self.current_shot_seed, + simulated_op_count: self.simulated_op_count, + num_operations: ops.len(), + operations: ops.to_vec(), + lowered_quantum_ops: lowered_trace, + }; + + if let Some(ref collector) = self.operation_trace_collector { + match collector.lock() { + Ok(mut guard) => guard.push(chunk.clone()), + Err(err) => warn!("Failed to store operation trace chunk in memory: {err}"), + } + } + + if let Some(ref trace_dir) = self.operation_trace_dir { + if let Err(err) = fs::create_dir_all(trace_dir) { + warn!( + "Failed to create operation trace directory {}: {err}", + trace_dir.display() + ); + return; + } + + let trace_path = trace_dir.join(file_name); + let serialized = match serde_json::to_string_pretty(&chunk) { + Ok(serialized) => serialized, + Err(err) => { + warn!( + "Failed to serialize operation trace chunk for {}: {err}", + trace_path.display() + ); + return; + } + }; + + if let Err(err) = fs::write(&trace_path, serialized) { + warn!( + "Failed to write operation trace chunk {}: {err}", + trace_path.display() + ); + } + } + } + /// Start the LLVM program execution in a worker thread /// /// Uses a persistent worker thread to avoid TLS allocation issues from @@ -573,10 +999,10 @@ impl QisEngine { Ok(()) } - /// Get pending operations from the dynamic execution + /// Get pending operations from the dynamic execution. /// - /// This reads from the global storage, which the worker thread - /// populates before blocking. + /// The worker exports only newly generated operations before each wait, so + /// this handoff stays proportional to fresh work instead of full history. fn get_dynamic_operations(&mut self) -> Option> { let state = self.dynamic_state.as_ref()?; let handle = state.sync_handle.as_ref()?; @@ -602,22 +1028,13 @@ impl QisEngine { if let Some(result) = result { match result { Ok((collector, interface)) => { - let total_ops = collector.operations.len(); + let operations = collector.operations; + let remaining_ops = operations.len(); debug!( - "Worker completed with {} total operations, {} already simulated", - total_ops, self.simulated_op_count + "Worker completed with {} remaining operations after {} already simulated", + remaining_ops, self.simulated_op_count ); - // Only store NEW operations (those after what we already simulated) - if total_ops > self.simulated_op_count { - self.pending_dynamic_ops = - collector.operations[self.simulated_op_count..].to_vec(); - debug!( - "Storing {} new operations for final processing", - self.pending_dynamic_ops.len() - ); - } else { - self.pending_dynamic_ops.clear(); - } + self.pending_dynamic_ops = operations; self.interface = Some(interface); if let Some(ref mut state) = self.dynamic_state { state.execution_complete = true; @@ -648,19 +1065,6 @@ impl QisEngine { self.dynamic_state = None; self.pending_dynamic_ops.clear(); } - - /// Convert a list of Operations to `QuantumOps` for the quantum engine - fn operations_to_quantum_ops(ops: &[Operation]) -> Vec { - ops.iter() - .filter_map(|op| { - if let Operation::Quantum(qop) = op { - Some(qop.clone()) - } else { - None - } - }) - .collect() - } } impl Engine for QisEngine { @@ -710,7 +1114,13 @@ impl Engine for QisEngine { impl ClassicalEngine for QisEngine { fn num_qubits(&self) -> usize { - let num_qubits = self.runtime.num_qubits(); + // The trait contract asks for the number of simulator slots required, + // not the count of live program handles: freed handles shrink + // `active_qubit_slots.len()` but never shrink the simulator, so we + // return the physical-slot high-water mark instead. The runtime can + // report its own baseline (e.g. from `allocated_qubits` metadata) and + // we take the larger of the two. + let num_qubits = self.runtime.num_qubits().max(self.num_physical_slots); debug!("QisEngine: num_qubits() returning {num_qubits}"); num_qubits } @@ -732,7 +1142,7 @@ impl ClassicalEngine for QisEngine { debug!("QisEngine: Operation: {op:?}"); } let quantum_ops: Vec = ops; - let msg = self.operations_to_bytemessage(quantum_ops)?; + let msg = self.quantum_ops_to_bytemessage(quantum_ops)?; debug!( "QisEngine: Generated ByteMessage with {} measurement mappings", self.measurement_mapping.len() @@ -832,9 +1242,7 @@ impl ClassicalEngine for QisEngine { debug!("QisEngine::handle_measurements called"); // Extract measurements from ByteMessage - let measurements = message - .outcomes() - .map_err(|e| PecosError::Generic(format!("Failed to parse measurements: {e}")))?; + let measurements = Self::parse_measurement_outcomes(&message)?; debug!( "QisEngine: Received {} measurements: {:?}", @@ -847,28 +1255,15 @@ impl ClassicalEngine for QisEngine { self.measurement_mapping ); - // Convert to BTreeMap for the runtime and store for get_results() - let mut measurement_map = BTreeMap::new(); - for (idx, &value) in measurements.iter().enumerate() { - if idx < self.measurement_mapping.len() { - let result_id = self.measurement_mapping[idx]; - let bool_value = value != 0; - measurement_map.insert(result_id, bool_value); - - // Store for get_results() - self.measurement_results.insert(result_id, bool_value); - debug!("QisEngine: Stored measurement result_id={result_id}, value={bool_value}"); - } - } + let updates = Self::map_measurements(&self.measurement_mapping, &measurements); + self.store_measurement_updates(&updates); debug!( "QisEngine: Final measurement_results: {:?}", self.measurement_results ); - self.runtime - .provide_measurements(measurement_map) - .map_err(|e| PecosError::Generic(format!("Failed to provide measurements: {e}"))) + self.provide_measurement_updates_to_runtime(&updates) } fn compile(&self) -> Result<(), PecosError> { @@ -916,6 +1311,7 @@ impl ControlEngine for QisEngine { self.measurement_mapping.clear(); self.pending_dynamic_ops.clear(); self.simulated_op_count = 0; + self.reset_qubit_slots(); debug!("QisEngine: Cleared previous measurement results for new shot"); // Generate a per-shot seed from our RNG @@ -924,6 +1320,7 @@ impl ControlEngine for QisEngine { // Store the shot seed for quantum engine access self.current_shot_seed = Some(shot_seed); + self.begin_trace_shot(); // Reset the runtime to ensure clean state for new shot self.runtime @@ -946,16 +1343,16 @@ impl ControlEngine for QisEngine { debug!("Worker needs result for id={result_id}"); // Get pending operations if let Some(ops) = self.get_dynamic_operations() { - self.pending_dynamic_ops.clone_from(&ops); // Track how many operations we're sending for simulation self.simulated_op_count = ops.len(); - debug!( - "Tracking {} operations as simulated", - self.simulated_op_count - ); - let quantum_ops = Self::operations_to_quantum_ops(&ops); - if !quantum_ops.is_empty() { - let commands = self.operations_to_bytemessage(quantum_ops)?; + if !ops.is_empty() { + let commands = self.operations_to_bytemessage(&ops)?; + self.trace_operations_chunk( + "pending_start", + &ops, + Some(result_id), + Some(&commands), + ); return Ok(EngineStage::NeedsProcessing(commands)); } } @@ -966,14 +1363,10 @@ impl ControlEngine for QisEngine { // Worker completed but we still need to process any pending operations // through the quantum engine (e.g., programs without measurement-dependent conditionals) if !self.pending_dynamic_ops.is_empty() { - let quantum_ops = Self::operations_to_quantum_ops(&self.pending_dynamic_ops); - self.pending_dynamic_ops.clear(); - if !quantum_ops.is_empty() { - debug!( - "Worker completed - sending {} final operations to quantum engine", - quantum_ops.len() - ); - let commands = self.operations_to_bytemessage(quantum_ops)?; + let final_ops = std::mem::take(&mut self.pending_dynamic_ops); + if !final_ops.is_empty() { + let commands = self.operations_to_bytemessage(&final_ops)?; + self.trace_operations_chunk("pending_final", &final_ops, None, Some(&commands)); return Ok(EngineStage::NeedsProcessing(commands)); } } @@ -999,10 +1392,16 @@ impl ControlEngine for QisEngine { )); } - // Process the response from quantum engine - if NoiseUtils::has_measurements(&input) { - self.handle_measurements(input.clone())?; - } + let measurement_updates = if NoiseUtils::has_measurements(&input) { + let measurements = Self::parse_measurement_outcomes(&input)?; + let mapping = std::mem::take(&mut self.measurement_mapping); + let updates = Self::map_measurements(&mapping, &measurements); + self.store_measurement_updates(&updates); + self.provide_measurement_updates_to_runtime(&updates)?; + updates + } else { + Vec::new() + }; // First, check if worker already completed (before processing anything else) // This avoids unnecessary work if the worker finished @@ -1010,10 +1409,10 @@ impl ControlEngine for QisEngine { debug!("Worker already complete, finishing shot"); // Process any final operations if !self.pending_dynamic_ops.is_empty() { - let quantum_ops = Self::operations_to_quantum_ops(&self.pending_dynamic_ops); - if !quantum_ops.is_empty() { - let commands = self.operations_to_bytemessage(quantum_ops)?; - self.pending_dynamic_ops.clear(); + let final_ops = std::mem::take(&mut self.pending_dynamic_ops); + if !final_ops.is_empty() { + let commands = self.operations_to_bytemessage(&final_ops)?; + self.trace_operations_chunk("pending_final", &final_ops, None, Some(&commands)); return Ok(EngineStage::NeedsProcessing(commands)); } } @@ -1021,27 +1420,14 @@ impl ControlEngine for QisEngine { return Ok(EngineStage::Complete(shot)); } - // Extract measurements from quantum engine response - let measurements = input - .outcomes() - .map_err(|e| PecosError::Generic(format!("Failed to parse measurements: {e}")))?; - - // Map measurement values to result IDs and provide to worker - for (idx, &value) in measurements.iter().enumerate() { - if idx < self.measurement_mapping.len() { - let result_id = self.measurement_mapping[idx]; - let bool_value = value != 0; - self.measurement_results.insert(result_id, bool_value); - debug!( - "Stored and providing measurement: result_id={result_id} value={bool_value}" - ); - // Provide result to worker thread - self.set_dynamic_result(result_id as u64, bool_value)?; - } + // Provide new measurement values to the dynamic worker thread. + for &(result_id, value) in &measurement_updates { + debug!("Stored and providing measurement: result_id={result_id} value={value}"); + self.set_dynamic_result(result_id as u64, value)?; } // Signal that results are ready - if !measurements.is_empty() { + if !measurement_updates.is_empty() { self.signal_dynamic_result_ready()?; } @@ -1058,32 +1444,25 @@ impl ControlEngine for QisEngine { // This is safe because result IDs are small sequential integers #[allow(clippy::cast_possible_truncation)] let result_key = result_id as usize; - if self.measurement_results.contains_key(&result_key) { + if let Some(&value) = self.measurement_results.get(&result_key) { debug!("Result {result_id} already available, signaling immediately"); // Re-set the result in global storage (in case it was cleared) - let value = self.measurement_results[&result_key]; self.set_dynamic_result(result_id, value)?; self.signal_dynamic_result_ready()?; // Continue loop to wait for next result or completion } else { - // Get pending operations + // Get newly exported operations. if let Some(ops) = self.get_dynamic_operations() { - // Only process NEW operations (after what we already simulated) - if ops.len() > self.simulated_op_count { - let new_ops: Vec = ops[self.simulated_op_count..].to_vec(); - // Update count to include these new operations - self.simulated_op_count = ops.len(); - debug!( - "Processing {} new operations, total simulated: {}", - new_ops.len(), - self.simulated_op_count + self.simulated_op_count += ops.len(); + if !ops.is_empty() { + let commands = self.operations_to_bytemessage(&ops)?; + self.trace_operations_chunk( + "pending_continue", + &ops, + Some(result_id), + Some(&commands), ); - let quantum_ops = Self::operations_to_quantum_ops(&new_ops); - self.pending_dynamic_ops = new_ops; - if !quantum_ops.is_empty() { - let commands = self.operations_to_bytemessage(quantum_ops)?; - return Ok(EngineStage::NeedsProcessing(commands)); - } + return Ok(EngineStage::NeedsProcessing(commands)); } } } @@ -1094,10 +1473,10 @@ impl ControlEngine for QisEngine { debug!("Worker completed after wait"); // Process any final operations if !self.pending_dynamic_ops.is_empty() { - let quantum_ops = Self::operations_to_quantum_ops(&self.pending_dynamic_ops); - if !quantum_ops.is_empty() { - let commands = self.operations_to_bytemessage(quantum_ops)?; - self.pending_dynamic_ops.clear(); + let final_ops = std::mem::take(&mut self.pending_dynamic_ops); + if !final_ops.is_empty() { + let commands = self.operations_to_bytemessage(&final_ops)?; + self.trace_operations_chunk("pending_final", &final_ops, None, Some(&commands)); return Ok(EngineStage::NeedsProcessing(commands)); } } @@ -1119,3 +1498,133 @@ impl ControlEngine for QisEngine { // Tests for QisEngine are in integration tests since they require // actual interface and runtime implementations. + +#[cfg(test)] +mod tests { + use super::*; + use crate::runtime::{ClassicalState, Result as RuntimeResult}; + use tempfile::TempDir; + + #[derive(Clone, Default)] + struct DummyRuntime { + state: ClassicalState, + } + + impl QisRuntime for DummyRuntime { + fn load_interface(&mut self, _interface: OperationList) -> RuntimeResult<()> { + Ok(()) + } + + fn execute_until_quantum(&mut self) -> RuntimeResult>> { + Ok(None) + } + + fn provide_measurements( + &mut self, + _measurements: BTreeMap, + ) -> RuntimeResult<()> { + Ok(()) + } + + fn get_classical_state(&self) -> &ClassicalState { + &self.state + } + + fn get_classical_state_mut(&mut self) -> &mut ClassicalState { + &mut self.state + } + + fn is_complete(&self) -> bool { + true + } + + fn num_qubits(&self) -> usize { + 1 + } + } + + #[test] + fn test_operation_trace_chunk_writes_json() { + let temp_dir = TempDir::new().expect("tempdir"); + let mut engine = QisEngine::with_runtime(Box::new(DummyRuntime::default())); + engine.set_operation_trace_dir(temp_dir.path()); + let collector: OperationTraceStore = Arc::new(Mutex::new(Vec::new())); + engine.set_operation_trace_collector(collector.clone()); + engine.current_shot_seed = Some(123); + engine.begin_trace_shot(); + + let ops = vec![ + Operation::AllocateQubit { id: 0 }, + QuantumOp::H(0).into(), + QuantumOp::Measure(0, 7).into(), + ]; + let commands = engine + .operations_to_bytemessage(&ops) + .expect("convert ops to bytemessage"); + engine.trace_operations_chunk("unit_test", &ops, Some(7), Some(&commands)); + + let mut trace_files = std::fs::read_dir(temp_dir.path()) + .expect("read trace dir") + .map(|entry| entry.expect("dir entry").path()) + .collect::>(); + trace_files.sort(); + assert_eq!(trace_files.len(), 1); + + let trace_json = std::fs::read_to_string(&trace_files[0]).expect("read trace json"); + let value: serde_json::Value = serde_json::from_str(&trace_json).expect("parse trace json"); + + assert_eq!(value["format"], "pecos_qis_operation_trace_v1"); + assert_eq!(value["stage"], "unit_test"); + assert_eq!(value["shot_index"], 1); + assert_eq!(value["waiting_for_result_id"], 7); + assert_eq!(value["current_shot_seed"], 123); + assert_eq!(value["num_operations"], 3); + assert_eq!(value["operations"][0]["AllocateQubit"]["id"], 0); + assert_eq!(value["operations"][1]["Quantum"]["H"], 0); + assert_eq!(value["lowered_quantum_ops"][0]["gate_type"], "PZ"); + assert_eq!(value["lowered_quantum_ops"][1]["gate_type"], "H"); + assert_eq!(value["lowered_quantum_ops"][2]["gate_type"], "MZ"); + + let in_memory = collector.lock().expect("collector lock"); + assert_eq!(in_memory.len(), 1); + assert_eq!(in_memory[0].stage, "unit_test"); + assert_eq!(in_memory[0].lowered_quantum_ops[0].gate_type, "PZ"); + } + + #[test] + fn test_operations_to_bytemessage_accepts_implicit_static_qubit_handles() { + let mut engine = QisEngine::with_runtime(Box::new(DummyRuntime::default())); + let ops = vec![QuantumOp::H(0).into(), QuantumOp::Measure(0, 7).into()]; + + let commands = engine + .operations_to_bytemessage(&ops) + .expect("convert ops with implicit static handles"); + + let lowered = commands.quantum_ops().expect("parse lowered commands"); + assert_eq!(lowered.len(), 2); + assert_eq!(lowered[0].gate_type.to_string(), "H"); + assert_eq!(lowered[0].qubits.as_slice(), &[pecos_core::QubitId(0)]); + assert_eq!(lowered[1].gate_type.to_string(), "MZ"); + assert_eq!(lowered[1].qubits.as_slice(), &[pecos_core::QubitId(0)]); + } + + #[test] + fn test_operations_to_bytemessage_rejects_use_after_release_without_reallocate() { + let mut engine = QisEngine::with_runtime(Box::new(DummyRuntime::default())); + let ops = vec![ + Operation::AllocateQubit { id: 0 }, + QuantumOp::H(0).into(), + Operation::ReleaseQubit { id: 0 }, + QuantumOp::X(0).into(), + ]; + + let Err(err) = engine.operations_to_bytemessage(&ops) else { + panic!("released qubit reuse should error"); + }; + + assert!( + err.to_string().contains("not currently active"), + "unexpected error: {err}" + ); + } +} diff --git a/crates/pecos-qis/src/engine_builder.rs b/crates/pecos-qis/src/engine_builder.rs index 074336f80..adc994260 100644 --- a/crates/pecos-qis/src/engine_builder.rs +++ b/crates/pecos-qis/src/engine_builder.rs @@ -1,9 +1,10 @@ //! Builder for `QisEngine` that integrates with PECOS `sim()` API -use crate::{IntoQisInterface, QisEngine}; +use crate::{IntoQisInterface, OperationTraceStore, QisEngine}; use pecos_core::errors::PecosError; use pecos_engines::ClassicalControlEngineBuilder; use pecos_qis_ffi_types::OperationCollector; +use std::path::{Path, PathBuf}; /// Builder for creating `QisEngine` instances pub struct QisEngineBuilder { @@ -11,6 +12,8 @@ pub struct QisEngineBuilder { interface: Option, interface_builder: Option>, program_source: Option, // Store original program source for loading + operation_trace_dir: Option, + operation_trace_collector: Option, } impl Clone for QisEngineBuilder { @@ -24,6 +27,8 @@ impl Clone for QisEngineBuilder { .as_ref() .map(|b| dyn_clone::clone_box(&**b)), program_source: self.program_source.clone(), + operation_trace_dir: self.operation_trace_dir.clone(), + operation_trace_collector: self.operation_trace_collector.clone(), } } } @@ -37,9 +42,29 @@ impl QisEngineBuilder { interface: None, interface_builder: None, program_source: None, + operation_trace_dir: None, + operation_trace_collector: None, } } + /// Dump Helios-collected operation chunks to the given directory as JSON. + /// + /// This captures the lowered QIS operation stream before it is compressed into + /// `ByteMessage` commands for the quantum engine, making it the most faithful + /// circuit-aware trace seam currently available in PECOS. + #[must_use] + pub fn trace_operations_to(mut self, trace_dir: impl AsRef) -> Self { + self.operation_trace_dir = Some(trace_dir.as_ref().to_path_buf()); + self + } + + /// Collect traced QIS batches in memory instead of requiring JSON output. + #[must_use] + pub fn trace_operations_in_memory_to(mut self, collector: OperationTraceStore) -> Self { + self.operation_trace_collector = Some(collector); + self + } + /// Set a pre-built interface (for testing) #[must_use] pub fn with_interface(mut self, interface: OperationCollector) -> Self { @@ -185,6 +210,21 @@ impl QisEngineBuilder { log::warn!("Bitcode programs not yet supported for interface loading"); } } + } else if let Some(hugr_prog) = any_program.downcast_ref::() { + #[cfg(feature = "hugr")] + { + self.program_source = Some(pecos_hugr_qis::compile_hugr_bytes_to_string( + &hugr_prog.hugr, + )?); + } + #[cfg(not(feature = "hugr"))] + { + let _ = hugr_prog; + return Err(PecosError::Processing( + "HUGR programs require the 'hugr' feature to enable HUGR-to-QIS lowering" + .to_string(), + )); + } } let interface = if let Some(builder) = &self.interface_builder { @@ -268,6 +308,12 @@ impl ClassicalControlEngineBuilder for QisEngineBuilder { log::debug!("Dynamic interface created successfully"); let mut engine = QisEngine::new(dynamic_interface, runtime); + if let Some(trace_dir) = self.operation_trace_dir { + engine.set_operation_trace_dir(trace_dir); + } + if let Some(collector) = self.operation_trace_collector { + engine.set_operation_trace_collector(collector); + } // Store the builder and program source so clones can recreate their interfaces engine.set_dynamic_config(dyn_clone::clone_box(&**builder), program_source); diff --git a/crates/pecos-qis/src/executor.rs b/crates/pecos-qis/src/executor.rs index f9572fce0..a950a981f 100644 --- a/crates/pecos-qis/src/executor.rs +++ b/crates/pecos-qis/src/executor.rs @@ -725,6 +725,12 @@ impl QisHeliosInterface { debug!("Executable directory: {}", exe_dir.display()); + let profile_order = if cfg!(debug_assertions) { + ["debug", "release"] + } else { + ["release", "debug"] + }; + let mut candidate_paths = vec![ exe_dir.join(&lib_name), exe_dir.join(format!("deps/{lib_name}")), @@ -737,20 +743,21 @@ impl QisHeliosInterface { if let Ok(current_dir) = std::env::current_dir() { debug!("Current directory: {}", current_dir.display()); - candidate_paths.push(current_dir.join(format!("target/debug/{lib_name}"))); - candidate_paths.push(current_dir.join(format!("target/debug/deps/{lib_name}"))); - candidate_paths.push(current_dir.join(format!("target/release/{lib_name}"))); - candidate_paths.push(current_dir.join(format!("target/release/deps/{lib_name}"))); + for profile in &profile_order { + candidate_paths.push(current_dir.join(format!("target/{profile}/{lib_name}"))); + candidate_paths.push(current_dir.join(format!("target/{profile}/deps/{lib_name}"))); + } // Search up the directory tree for workspace root (when running from Python) let mut search_dir = current_dir.as_path(); for _ in 0..5 { // Search up to 5 levels if let Some(parent) = search_dir.parent() { - candidate_paths.push(parent.join(format!("target/debug/{lib_name}"))); - candidate_paths.push(parent.join(format!("target/debug/deps/{lib_name}"))); - candidate_paths.push(parent.join(format!("target/release/{lib_name}"))); - candidate_paths.push(parent.join(format!("target/release/deps/{lib_name}"))); + for profile in &profile_order { + candidate_paths.push(parent.join(format!("target/{profile}/{lib_name}"))); + candidate_paths + .push(parent.join(format!("target/{profile}/deps/{lib_name}"))); + } search_dir = parent; } else { break; diff --git a/crates/pecos-qis/src/lib.rs b/crates/pecos-qis/src/lib.rs index 93e304148..44478f886 100644 --- a/crates/pecos-qis/src/lib.rs +++ b/crates/pecos-qis/src/lib.rs @@ -97,12 +97,11 @@ pub mod engine_builder; pub mod interface_impl; pub mod program; -pub use ccengine::QisEngine; +pub use ccengine::{LoweredQuantumGateTrace, OperationTraceChunk, OperationTraceStore, QisEngine}; pub use engine_builder::{QisEngineBuilder, qis_engine}; pub use program::{ InterfaceChoice, IntoQisInterface, ProgramType, QisEngineProgram, QisInterfaceBuilder, - QisInterfaceProvider, }; // ============================================================================ @@ -188,36 +187,38 @@ pub fn setup_qis_engine_with_runtime( Ok(Box::new(engine) as Box) } -/// Setup a QIS control engine for a program file (deprecated) +/// Create a QIS engine builder preconfigured with the default Selene simple runtime. /// -/// **Deprecated**: This function is deprecated because it relied on implicit runtime selection. -/// Use `setup_qis_engine_with_runtime` instead and provide an explicit runtime. -/// -/// # Parameters +/// # Errors /// -/// - `program_path`: Path to the QIS program file (.ll or .bc) +/// Returns an error if the default Selene simple runtime cannot be located or loaded. +#[cfg(feature = "selene")] +pub fn selene_engine() -> Result { + Ok(qis_engine() + .runtime(selene_simple_runtime()?) + .interface(helios_interface_builder())) +} + +/// Create a QIS engine builder preconfigured with a named Selene runtime plugin. /// -/// # Returns +/// # Errors /// -/// Returns an error directing users to use the explicit runtime version. +/// Returns an error if the requested Selene runtime plugin cannot be located or loaded. +#[cfg(feature = "selene")] +pub fn selene_engine_auto(lib_name: &str) -> Result { + Ok(qis_engine() + .runtime(selene_runtime_auto(lib_name)?) + .interface(helios_interface_builder())) +} + +/// Create a QIS engine builder preconfigured with the Selene soft-RZ runtime. /// /// # Errors -/// Always returns an error directing users to use `setup_qis_engine_with_runtime` instead. -#[deprecated( - since = "0.1.1", - note = "Use setup_qis_engine_with_runtime with an explicit runtime instead" -)] -pub fn setup_qis_engine( - _program_path: &Path, -) -> Result, PecosError> { - Err(PecosError::Processing( - "setup_qis_engine is deprecated.\n\ - \n\ - Please use setup_qis_engine_with_runtime and provide an explicit runtime:\n\ - \n\ - use pecos_qis::{setup_qis_engine_with_runtime, selene_simple_runtime};\n\ - \n\ - let engine = setup_qis_engine_with_runtime(path, selene_simple_runtime()?)?;" - .to_string(), - )) +/// +/// Returns an error if the Selene soft-RZ runtime cannot be located or loaded. +#[cfg(feature = "selene")] +pub fn selene_soft_rz_engine() -> Result { + Ok(qis_engine() + .runtime(selene_soft_rz_runtime()?) + .interface(helios_interface_builder())) } diff --git a/crates/pecos-qis/src/prelude.rs b/crates/pecos-qis/src/prelude.rs index 3d3b97056..05adeebe0 100644 --- a/crates/pecos-qis/src/prelude.rs +++ b/crates/pecos-qis/src/prelude.rs @@ -19,7 +19,6 @@ pub use crate::engine_builder::{QisEngineBuilder, qis_engine}; // Program types pub use crate::program::{ InterfaceChoice, IntoQisInterface, ProgramType, QisEngineProgram, QisInterfaceBuilder, - QisInterfaceProvider, }; // Convenience functions diff --git a/crates/pecos-qis/src/program.rs b/crates/pecos-qis/src/program.rs index d01775950..1ef2a6ec9 100644 --- a/crates/pecos-qis/src/program.rs +++ b/crates/pecos-qis/src/program.rs @@ -10,8 +10,6 @@ use pecos_core::errors::PecosError; use pecos_programs::{Hugr, Qis}; use pecos_qis_ffi_types::OperationCollector; -use std::process::Command; -use tempfile::NamedTempFile; /// A trait for types that can be converted into a `QisInterface` /// @@ -39,563 +37,6 @@ pub enum ProgramType { HugrBytes, } -/// Trait for different `QisInterface` implementation strategies -/// -/// This allows pluggable compilation strategies - Selene Helios compilation -/// or other future approaches. -pub trait QisInterfaceProvider: Send + Sync { - /// Get the interface (may involve compilation/linking) - /// - /// # Errors - /// Returns an error if the interface cannot be obtained (e.g., compilation/linking failures). - fn get_interface(&mut self) -> Result; - - /// Get provider type for debugging and logging - fn provider_type(&self) -> &'static str; - - /// Check if this provider can handle the given program type - fn can_handle(&self, program_type: &ProgramType) -> bool; - - /// Get any metadata about the compilation process - fn get_metadata(&self) -> std::collections::BTreeMap { - std::collections::BTreeMap::new() - } -} - -/// Selene Helios-based `QisInterface` provider -/// -/// This provider uses Selene's Helios compiler to compile QIS bitcode -/// into optimized quantum programs, then converts the result into a `QisInterface`. -#[derive(Debug)] -pub struct QisSeleneHeliosInterface { - program_data: Vec, - program_type: ProgramType, - metadata: std::collections::BTreeMap, - helios_config: HeliosConfig, -} - -/// Configuration for Selene Helios compilation -#[derive(Debug, Clone)] -pub struct HeliosConfig { - /// Optimization level (0-3) - pub opt_level: u8, - /// Target triple for compilation - pub target_triple: String, - /// Additional compilation flags - pub extra_flags: Vec, - /// Path to Selene installation - pub selene_path: Option, -} - -impl Default for HeliosConfig { - fn default() -> Self { - Self { - opt_level: 2, - target_triple: "native".to_string(), - extra_flags: Vec::new(), - selene_path: None, - } - } -} - -impl QisSeleneHeliosInterface { - /// Create a new Selene Helios interface provider from QIS bitcode - #[must_use] - pub fn from_bitcode(bitcode: Vec) -> Self { - Self::from_bitcode_with_config(bitcode, HeliosConfig::default()) - } - - /// Create a new Selene Helios interface provider with custom configuration - #[must_use] - pub fn from_bitcode_with_config(bitcode: Vec, config: HeliosConfig) -> Self { - let mut metadata = std::collections::BTreeMap::new(); - metadata.insert("bitcode_size".to_string(), bitcode.len().to_string()); - metadata.insert( - "compilation_strategy".to_string(), - "selene_helios".to_string(), - ); - metadata.insert("opt_level".to_string(), config.opt_level.to_string()); - - Self { - program_data: bitcode, - program_type: ProgramType::QisBitcode, - metadata, - helios_config: config, - } - } - - /// Create a new Selene Helios interface provider from HUGR bytes - #[must_use] - pub fn from_hugr_bytes(hugr_bytes: Vec) -> Self { - Self::from_hugr_bytes_with_config(hugr_bytes, HeliosConfig::default()) - } - - /// Create a new Selene Helios interface provider from HUGR bytes with custom configuration - #[must_use] - pub fn from_hugr_bytes_with_config(hugr_bytes: Vec, config: HeliosConfig) -> Self { - let mut metadata = std::collections::BTreeMap::new(); - metadata.insert("hugr_size".to_string(), hugr_bytes.len().to_string()); - metadata.insert( - "compilation_strategy".to_string(), - "selene_helios".to_string(), - ); - metadata.insert("opt_level".to_string(), config.opt_level.to_string()); - - Self { - program_data: hugr_bytes, - program_type: ProgramType::HugrBytes, - metadata, - helios_config: config, - } - } - - /// Create from LLVM IR text by converting to bitcode - #[must_use] - pub fn from_llvm_ir(llvm_ir: &str) -> Self { - #[cfg(feature = "llvm")] - { - // Convert LLVM IR text to bitcode using inkwell - use inkwell::context::Context; - use inkwell::targets::{InitializationConfig, Target}; - - // Initialize LLVM targets - Target::initialize_native(&InitializationConfig::default()).ok(); - - let context = Context::create(); - let bitcode = match context.create_module_from_ir( - inkwell::memory_buffer::MemoryBuffer::create_from_memory_range( - llvm_ir.as_bytes(), - "llvm_ir", - ), - ) { - Ok(module) => { - // Write module to bitcode - module.write_bitcode_to_memory().as_slice().to_vec() - } - Err(e) => { - log::error!("Failed to convert LLVM IR to bitcode: {e}"); - // Store the IR text as-is and let Helios handle it - llvm_ir.as_bytes().to_vec() - } - }; - - let mut interface = Self::from_bitcode(bitcode); - interface - .metadata - .insert("original_format".to_string(), "llvm_ir".to_string()); - interface - .metadata - .insert("ir_size".to_string(), llvm_ir.len().to_string()); - interface - } - - #[cfg(not(feature = "llvm"))] - { - // Without LLVM support, store the IR text as-is and let Helios handle it - let mut interface = Self::from_bitcode(llvm_ir.as_bytes().to_vec()); - interface - .metadata - .insert("original_format".to_string(), "llvm_ir".to_string()); - interface - .metadata - .insert("ir_size".to_string(), llvm_ir.len().to_string()); - interface - .metadata - .insert("llvm_conversion".to_string(), "skipped".to_string()); - interface - } - } - - /// Compile the program using Selene Helios and convert to `QisInterface` - fn compile_with_helios(&mut self) -> Result { - log::info!( - "Using Selene Helios compilation strategy for {:?}", - self.program_type - ); - - match self.program_type { - ProgramType::QisBitcode => { - self.compile_bitcode_with_helios() - } - ProgramType::HugrBytes => { - self.compile_hugr_with_helios() - } - ProgramType::LlvmIr => { - Err(PecosError::Generic( - "Selene Helios interface cannot compile LLVM IR text directly.\n\ - \n\ - The Helios interface is designed for HUGR bytes and QIS bitcode formats.\n\ - For LLVM IR text, please convert to bitcode first or use a different interface.\n\ - \n\ - This is a deprecated code path - modern PECOS uses Selene for all QIS programs.".to_string() - )) - } - } - } - - /// Compile QIS bitcode using Selene Helios - fn compile_bitcode_with_helios(&mut self) -> Result { - // Compile bitcode to LLVM IR using Selene Helios - let _llvm_ir = self.compile_bitcode_to_llvm_ir()?; - - // This old implementation is deprecated - use QisHeliosInterface instead - Err(PecosError::Processing( - "QisSeleneHeliosInterface is deprecated. Use pecos_qis::QisHeliosInterface instead." - .to_string(), - )) - } - - /// Compile HUGR bytes using Selene Helios - fn compile_hugr_with_helios(&mut self) -> Result { - // Use Selene HUGR compiler (no fallback) - let _llvm_ir = compile_hugr_with_selene(&self.program_data)?; - - // This old implementation is deprecated - use QisHeliosInterface instead - Err(PecosError::Processing( - "QisSeleneHeliosInterface is deprecated. Use pecos_qis::QisHeliosInterface instead." - .to_string(), - )) - } - - /// Compile QIS bitcode to LLVM IR using Selene Helios compiler - fn compile_bitcode_to_llvm_ir(&mut self) -> Result { - use std::io::Write; - use tempfile::NamedTempFile; - - // Write bitcode to a temporary file - let mut bitcode_file = NamedTempFile::new() - .map_err(|e| PecosError::Generic(format!("Failed to create temp file: {e}")))?; - bitcode_file - .write_all(&self.program_data) - .map_err(|e| PecosError::Generic(format!("Failed to write bitcode: {e}")))?; - - // Try multiple strategies to find and use Selene Helios - self.try_selene_helios_compilation(&bitcode_file) - } - - /// Try different strategies for Selene Helios compilation - fn try_selene_helios_compilation( - &mut self, - bitcode_file: &NamedTempFile, - ) -> Result { - let strategy_names = [ - "Custom Path", - "Environment Variable", - "Standard Locations", - "Conda Environment", - "System Installation", - ]; - - let strategies = [ - self.try_custom_selene_path(bitcode_file), - self.try_env_selene_path(bitcode_file), - self.try_standard_selene_locations(bitcode_file), - self.try_conda_selene(bitcode_file), - self.try_system_selene(bitcode_file), - ]; - - for (strategy_name, result) in strategy_names.iter().zip(strategies.iter()) { - match result { - Ok(llvm_ir) => { - log::info!("Selene Helios compilation succeeded using: {strategy_name}"); - self.metadata - .insert("helios_strategy".to_string(), (*strategy_name).to_string()); - self.metadata - .insert("helios_compilation".to_string(), "success".to_string()); - self.metadata - .insert("llvm_ir_size".to_string(), llvm_ir.len().to_string()); - return Ok(llvm_ir.clone()); - } - Err(e) => { - log::debug!("Selene Helios strategy '{strategy_name}' failed: {e}"); - self.metadata.insert( - format!( - "helios_strategy_{}_error", - strategy_name.to_lowercase().replace(' ', "_") - ), - e.to_string(), - ); - } - } - } - - // If all strategies fail, provide helpful error message - Err(PecosError::Generic(format!( - "Selene Helios compilation failed. Unable to find Selene installation after trying: {}. \n\ - \n\ - To use Selene Helios interface, you need to:\n\ - 1. Install Selene (https://github.com/Quantinuum/selene)\n\ - 2. Set SELENE_PATH environment variable to the Selene directory\n\ - \n\ - Selene is the only supported interface for QIS programs in modern PECOS.", - strategy_names.join(", ") - ))) - } - - /// Try compilation using user-provided Selene path - fn try_custom_selene_path(&self, bitcode_file: &NamedTempFile) -> Result { - let selene_path = self - .helios_config - .selene_path - .as_ref() - .ok_or_else(|| PecosError::Generic("No custom Selene path provided".to_string()))?; - - self.run_selene_helios_compiler(selene_path, bitcode_file) - } - - /// Try compilation using `SELENE_PATH` environment variable - fn try_env_selene_path(&self, bitcode_file: &NamedTempFile) -> Result { - let selene_path = std::env::var("SELENE_PATH") - .map_err(|_| PecosError::Generic("SELENE_PATH not set".to_string()))?; - - let path = std::path::PathBuf::from(selene_path); - self.run_selene_helios_compiler(&path, bitcode_file) - } - - /// Try compilation using standard Selene installation locations - fn try_standard_selene_locations( - &self, - bitcode_file: &NamedTempFile, - ) -> Result { - let standard_paths = [ - "/home/ciaranra/Repos/cl_projects/gup/selene", - "/opt/selene", - "/usr/local/selene", - "~/selene", - "./selene", - "../selene", - ]; - - for path_str in &standard_paths { - let path = std::path::PathBuf::from(path_str); - if path.exists() && path.join("selene-compilers/helios/python").exists() { - log::debug!("Found Selene at standard location: {}", path.display()); - return self.run_selene_helios_compiler(&path, bitcode_file); - } - } - - Err(PecosError::Generic( - "No Selene found in standard locations".to_string(), - )) - } - - /// Try compilation using conda environment - fn try_conda_selene(&self, bitcode_file: &NamedTempFile) -> Result { - // Check if we're in a conda environment with Selene - let python_script = r" -import sys -try: - import selene_helios_compiler - print(selene_helios_compiler.__file__) -except ImportError: - sys.exit(1) -" - .to_string(); - - let output = Command::new("python3") - .arg("-c") - .arg(&python_script) - .output() - .map_err(|e| PecosError::Generic(format!("Failed to check conda Selene: {e}")))?; - - if !output.status.success() { - return Err(PecosError::Generic( - "Selene not available in conda environment".to_string(), - )); - } - - // Run compilation directly using available Python module - self.run_conda_selene_compilation(bitcode_file) - } - - /// Try compilation using system-installed Selene - fn try_system_selene(&self, bitcode_file: &NamedTempFile) -> Result { - // Check if selene-helios command is available in PATH - let output = Command::new("which") - .arg("selene-helios") - .output() - .map_err(|_| PecosError::Generic("selene-helios not in PATH".to_string()))?; - - if !output.status.success() { - return Err(PecosError::Generic( - "selene-helios command not found".to_string(), - )); - } - - // Use command-line tool - self.run_system_selene_compilation(bitcode_file) - } - - /// Run Selene Helios compiler from a specific path - fn run_selene_helios_compiler( - &self, - selene_path: &std::path::Path, - bitcode_file: &NamedTempFile, - ) -> Result { - let helios_python_path = selene_path.join("selene-compilers/helios/python"); - - if !helios_python_path.exists() { - return Err(PecosError::Generic(format!( - "Selene Helios Python path not found: {}", - helios_python_path.display() - ))); - } - - let python_script = format!( - r#" -import sys -sys.path.insert(0, '{helios_python_path}') - -try: - from selene_helios_compiler import compile_bitcode_to_llvm_ir -except ImportError as e: - print(f"Failed to import Selene Helios compiler: {{e}}", file=sys.stderr) - sys.exit(1) - -try: - with open('{bitcode_path}', 'rb') as f: - bitcode = f.read() - - llvm_ir = compile_bitcode_to_llvm_ir( - bitcode, - opt_level={opt_level}, - target_triple='{target_triple}' - ) - print(llvm_ir) -except Exception as e: - print(f"Compilation failed: {{e}}", file=sys.stderr) - sys.exit(1) -"#, - helios_python_path = helios_python_path.display(), - bitcode_path = bitcode_file.path().display(), - opt_level = self.helios_config.opt_level, - target_triple = self.helios_config.target_triple - ); - - let output = Command::new("python3") - .arg("-c") - .arg(&python_script) - .output() - .map_err(|e| PecosError::Generic(format!("Failed to run Selene Helios: {e}")))?; - - if !output.status.success() { - let stderr = String::from_utf8_lossy(&output.stderr); - return Err(PecosError::Generic(format!( - "Selene Helios compilation failed: {stderr}" - ))); - } - - let llvm_ir = String::from_utf8(output.stdout) - .map_err(|e| PecosError::Generic(format!("Invalid UTF-8 output: {e}")))?; - - log::debug!( - "Successfully compiled bitcode using Selene Helios from: {}", - selene_path.display() - ); - Ok(llvm_ir.trim().to_string()) - } - - /// Run Selene Helios compilation using conda environment - fn run_conda_selene_compilation( - &self, - bitcode_file: &NamedTempFile, - ) -> Result { - let python_script = format!( - r#" -import selene_helios_compiler - -try: - with open('{bitcode_path}', 'rb') as f: - bitcode = f.read() - - llvm_ir = selene_helios_compiler.compile_bitcode_to_llvm_ir( - bitcode, - opt_level={opt_level}, - target_triple='{target_triple}' - ) - print(llvm_ir) -except Exception as e: - import sys - print(f"Conda Selene compilation failed: {{e}}", file=sys.stderr) - sys.exit(1) -"#, - bitcode_path = bitcode_file.path().display(), - opt_level = self.helios_config.opt_level, - target_triple = self.helios_config.target_triple - ); - - let output = Command::new("python3") - .arg("-c") - .arg(&python_script) - .output() - .map_err(|e| PecosError::Generic(format!("Failed to run conda Selene: {e}")))?; - - if !output.status.success() { - let stderr = String::from_utf8_lossy(&output.stderr); - return Err(PecosError::Generic(format!( - "Conda Selene compilation failed: {stderr}" - ))); - } - - let llvm_ir = String::from_utf8(output.stdout) - .map_err(|e| PecosError::Generic(format!("Invalid UTF-8 output: {e}")))?; - - Ok(llvm_ir.trim().to_string()) - } - - /// Run Selene Helios compilation using system command - fn run_system_selene_compilation( - &self, - bitcode_file: &NamedTempFile, - ) -> Result { - let output = Command::new("selene-helios") - .arg("compile") - .arg("--input") - .arg(bitcode_file.path()) - .arg("--output-format") - .arg("llvm-ir") - .arg("--opt-level") - .arg(self.helios_config.opt_level.to_string()) - .arg("--target-triple") - .arg(&self.helios_config.target_triple) - .output() - .map_err(|e| PecosError::Generic(format!("Failed to run system Selene: {e}")))?; - - if !output.status.success() { - let stderr = String::from_utf8_lossy(&output.stderr); - return Err(PecosError::Generic(format!( - "System Selene compilation failed: {stderr}" - ))); - } - - let llvm_ir = String::from_utf8(output.stdout) - .map_err(|e| PecosError::Generic(format!("Invalid UTF-8 output: {e}")))?; - - Ok(llvm_ir.trim().to_string()) - } -} - -impl QisInterfaceProvider for QisSeleneHeliosInterface { - fn get_interface(&mut self) -> Result { - self.compile_with_helios() - } - - fn provider_type(&self) -> &'static str { - "Selene Helios" - } - - fn can_handle(&self, program_type: &ProgramType) -> bool { - matches!( - program_type, - ProgramType::QisBitcode | ProgramType::HugrBytes - ) - } - - fn get_metadata(&self) -> std::collections::BTreeMap { - self.metadata.clone() - } -} - /// Implement `IntoQisInterface` for `OperationCollector` itself (identity conversion) impl IntoQisInterface for OperationCollector { fn into_qis_interface(self) -> Result { @@ -811,70 +252,3 @@ impl From for QisEngineProgram { // Tests for program conversion require actual interface implementations // and are in the integration test files. - -/// Compile HUGR bytes using Selene's compiler -/// -/// This uses Selene's proven HUGR→LLVM compiler, ensuring proper qubit ID -/// management and QIS function generation. Returns explicit error if Selene is not available. -fn compile_hugr_with_selene(hugr_bytes: &[u8]) -> Result { - log::info!("Compiling HUGR with Selene compiler (required)"); - - // Use Selene's Python compiler - no fallbacks - compile_hugr_with_selene_python(hugr_bytes).map_err(|e| { - PecosError::Generic(format!( - "Selene Helios compilation failed: {e}\n\n\ - To use Helios interface, ensure Selene is installed and available:\n\ - 1. Ensure Selene repository is at ../selene or ../../../selene\n\ - 2. Build Selene compilers: 'cargo build --release' in Selene directory\n\ - \n\ - Selene is the only supported interface for QIS programs." - )) - }) -} - -/// Compile HUGR using Selene's Python compiler -fn compile_hugr_with_selene_python(hugr_bytes: &[u8]) -> Result { - use std::io::Write; - use tempfile::NamedTempFile; - - // Write HUGR bytes to a temporary file - let mut hugr_file = NamedTempFile::new() - .map_err(|e| PecosError::Generic(format!("Failed to create temp file: {e}")))?; - hugr_file - .write_all(hugr_bytes) - .map_err(|e| PecosError::Generic(format!("Failed to write HUGR bytes: {e}")))?; - - // Call Selene's compiler using Python - let output = Command::new("python3") - .arg("-c") - .arg(format!( - r" -import sys -sys.path.insert(0, '{}/selene-compilers/hugr_qis/python') -from selene_hugr_qis_compiler import compile_to_llvm_ir - -with open('{}', 'rb') as f: - hugr_bytes = f.read() - -llvm_ir = compile_to_llvm_ir(hugr_bytes, opt_level=2, target_triple='native') -print(llvm_ir) -", - "/home/ciaranra/Repos/cl_projects/gup/selene", - hugr_file.path().display() - )) - .output() - .map_err(|e| PecosError::Generic(format!("Failed to run Selene compiler: {e}")))?; - - if !output.status.success() { - let stderr = String::from_utf8_lossy(&output.stderr); - return Err(PecosError::Generic(format!( - "Selene compiler failed: {stderr}" - ))); - } - - let llvm_ir = String::from_utf8(output.stdout) - .map_err(|e| PecosError::Generic(format!("Invalid UTF-8 output: {e}")))?; - - log::debug!("Successfully compiled HUGR using Selene compiler"); - Ok(llvm_ir) -} diff --git a/crates/pecos-quantum/src/circuit_display.rs b/crates/pecos-quantum/src/circuit_display.rs index 796672126..a2e61a01f 100644 --- a/crates/pecos-quantum/src/circuit_display.rs +++ b/crates/pecos-quantum/src/circuit_display.rs @@ -75,6 +75,7 @@ fn gate_symbol(gate_type: GateType) -> &'static str { GateType::I | GateType::Idle => "I", GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload => "XT", GateType::Custom => "?", + GateType::PauliOperatorMeta => "PO", } } @@ -217,7 +218,8 @@ fn gate_color(gate_type: GateType) -> CellColor { | GateType::U | GateType::R1XY | GateType::RXXRYYRZZ - | GateType::U2q => CellColor::None, + | GateType::U2q + | GateType::PauliOperatorMeta => CellColor::None, } } diff --git a/crates/pecos-quantum/src/dag_circuit.rs b/crates/pecos-quantum/src/dag_circuit.rs index a052ce158..fe281d7a7 100644 --- a/crates/pecos-quantum/src/dag_circuit.rs +++ b/crates/pecos-quantum/src/dag_circuit.rs @@ -313,74 +313,6 @@ impl TraversalWorkBuffers { } } -/// A handle returned by measurement operations, allowing metadata to be attached. -/// -/// This follows the simulator pattern where measurements break the chain, -/// but still allows attaching metadata via `.meta()`. -/// -/// # Example -/// ``` -/// use pecos_quantum::{DagCircuit, Attribute}; -/// -/// let mut circuit = DagCircuit::new(); -/// circuit.mz(&[0]).meta("basis", Attribute::String("Z".into())); -/// circuit.h(&[1]); // continue building -/// ``` -pub struct MeasureHandle<'a> { - circuit: &'a mut DagCircuit, - node: usize, -} - -impl MeasureHandle<'_> { - /// Returns the node ID of this measurement. - #[inline] - #[must_use] - pub fn node(&self) -> usize { - self.node - } - - /// Add metadata to this measurement. - /// - /// Returns `()` to break the chain, matching simulator behavior. - pub fn meta(self, key: &str, value: impl Into) { - self.circuit.set_gate_attr(self.node, key, value.into()); - } -} - -/// Handle returned by preparation operations to allow metadata attachment. -/// -/// This handle breaks the method chain (unlike regular gates), -/// but still allows attaching metadata via `.meta()`. -/// -/// # Example -/// ``` -/// use pecos_quantum::{DagCircuit, Attribute}; -/// -/// let mut circuit = DagCircuit::new(); -/// circuit.pz(&[0]).meta("reason", Attribute::String("reset".into())); -/// circuit.h(&[1]); // continue building -/// ``` -pub struct PrepHandle<'a> { - circuit: &'a mut DagCircuit, - node: usize, -} - -impl PrepHandle<'_> { - /// Returns the node ID of this preparation. - #[inline] - #[must_use] - pub fn node(&self) -> usize { - self.node - } - - /// Add metadata to this preparation. - /// - /// Returns `()` to break the chain. - pub fn meta(self, key: &str, value: impl Into) { - self.circuit.set_gate_attr(self.node, key, value.into()); - } -} - /// A directed acyclic graph representation of a quantum circuit. /// /// Each node in the DAG represents a quantum gate. Edges represent qubit wires @@ -416,6 +348,72 @@ impl PrepHandle<'_> { /// assert_eq!(circuit.gate_count(), 2); /// assert_eq!(circuit.wire_count(), 1); /// ``` +/// A measurement reference returned by [`DagCircuit::mz`]. +/// +/// Carries both the DAG node index and the qubit that was measured. +/// Dereferences to `usize` (the node index) for use in detector/observable +/// definitions. +#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] +pub struct MeasRef { + /// DAG node index. + pub node: usize, + /// Qubit that was measured. + pub qubit: QubitId, +} + +impl std::ops::Deref for MeasRef { + type Target = usize; + fn deref(&self) -> &usize { + &self.node + } +} + +impl From for usize { + fn from(m: MeasRef) -> usize { + m.node + } +} + +/// The role of a Pauli annotation in the circuit. +/// +/// All three kinds track the same thing -- whether a Pauli string flips due to +/// faults. The difference is how the answer is read out and what it means. +#[derive(Debug, Clone)] +pub enum AnnotationKind { + /// Stabilizer check: the Pauli should be deterministic (flip = error detected). + /// Stores measurement node indices for classical readout via XOR, plus + /// optional coordinates for visualization/matching. + Detector { + measurement_nodes: Vec, + coords: Vec, + }, + /// Logical observable: the Pauli's flip determines a logical outcome. + /// Stores measurement node indices for classical readout via XOR. + Observable { measurement_nodes: Vec }, + /// Tracked Pauli operator: no measurement readout. + /// Position is determined by a `PauliOperatorMeta` node in the DAG. + Operator, +} + +/// A unified Pauli annotation: detectors, observables, and tracked operators +/// are all Pauli strings tracked for flipping via backward propagation. +/// +/// - **Detectors** are stabilizer checks that should be +1 (noiseless). +/// Their Pauli is Z on the measured qubits. +/// - **Observables** are logical operators read out via measurements. +/// Their Pauli is Z on the measured qubits. +/// - **Operators** are arbitrary Pauli strings with no measurement readout. +/// Their Pauli is user-specified and their position comes from a meta-gate node. +#[derive(Debug, Clone)] +pub struct PauliAnnotation { + /// The Pauli string being tracked. + pub pauli: pecos_core::PauliString, + /// What role this annotation plays. + pub kind: AnnotationKind, + /// Optional label. + pub label: Option, +} + #[derive(Debug, Clone)] pub struct DagCircuit { /// The underlying DAG structure. @@ -430,6 +428,10 @@ pub struct DagCircuit { last_node: Option, /// Maximum qubit index seen so far (updated incrementally on gate addition). max_qubit: usize, + /// Unified Pauli annotations (detectors, observables, and tracked operators). + annotations: Vec, + /// Measurement labels (`node_index` → label). + measurement_labels: BTreeMap, } impl DagCircuit { @@ -443,6 +445,8 @@ impl DagCircuit { qubit_heads: BTreeMap::new(), last_node: None, max_qubit: 0, + annotations: Vec::new(), + measurement_labels: BTreeMap::new(), } } @@ -462,6 +466,8 @@ impl DagCircuit { qubit_heads: BTreeMap::new(), last_node: None, max_qubit: 0, + annotations: Vec::new(), + measurement_labels: BTreeMap::new(), } } @@ -1532,9 +1538,7 @@ impl DagCircuit { // -------------------- Measurement and preparation -------------------- // - // Measurements return MeasureHandle which allows .meta() but breaks - // further chaining, matching simulator behavior where mz returns - // MeasurementResult instead of &mut Self. + // Measurements return Vec (lightweight Copy handles). // Preparations return &mut Self and are chainable. /// Measure qubit(s) in the Z basis. @@ -1546,13 +1550,46 @@ impl DagCircuit { /// use pecos_quantum::DagCircuit; /// /// let mut circuit = DagCircuit::new(); - /// circuit.h(&[0]).mz(&[0, 1]); + /// circuit.h(&[0]); + /// let nodes = circuit.mz(&[0, 1]); + /// assert_eq!(nodes.len(), 2); /// ``` - pub fn mz(&mut self, qubits: &[impl Into + Copy]) -> &mut Self { - for &q in qubits { - self.add_gate_auto_wire(Gate::mz(&[q])); - } - self + pub fn mz(&mut self, qubits: &[impl Into + Copy]) -> Vec { + qubits + .iter() + .map(|&q| { + let qubit = q.into(); + let node = self.add_gate_auto_wire(Gate::mz(&[qubit])); + MeasRef { node, qubit } + }) + .collect() + } + + /// Measure qubits and label them. + /// + /// Labels are stored on the circuit and flow through to the sampler output. + pub fn mz_labeled(&mut self, entries: &[(impl Into + Copy, &str)]) -> Vec { + entries + .iter() + .map(|&(q, label)| { + let qubit = q.into(); + let node = self.add_gate_auto_wire(Gate::mz(&[qubit])); + let mref = MeasRef { node, qubit }; + self.set_measurement_label(node, label); + mref + }) + .collect() + } + + /// Set a label on a measurement node. + pub fn set_measurement_label(&mut self, node: usize, label: &str) { + self.measurement_labels.insert(node, label.to_string()); + } + + /// Get the label of a measurement node, if any. + #[must_use] + pub fn measurement_label(&self, node: usize) -> Option<&str> { + self.measurement_labels.get(&node).map(String::as_str) } /// Measure and free qubit(s) (destructive measurement). @@ -1563,6 +1600,224 @@ impl DagCircuit { self } + // ======================================================================== + // Detector and Observable Annotations + // ======================================================================== + + /// Annotate a detector: a set of measurements whose XOR should be + /// deterministic in the noiseless case. + /// + /// The Pauli string is automatically Z on the measured qubits. + /// + /// Returns the annotation index. + pub fn detector(&mut self, measurements: &[impl Into + Copy]) -> usize { + let meas_nodes: Vec = measurements.iter().map(|&m| m.into()).collect(); + let pauli = self.pauli_from_measurement_nodes(&meas_nodes); + let idx = self.annotations.len(); + self.annotations.push(PauliAnnotation { + pauli, + kind: AnnotationKind::Detector { + measurement_nodes: meas_nodes, + coords: Vec::new(), + }, + label: None, + }); + idx + } + + /// Annotate a labeled detector. + pub fn detector_labeled( + &mut self, + label: &str, + measurements: &[impl Into + Copy], + ) -> usize { + let meas_nodes: Vec = measurements.iter().map(|&m| m.into()).collect(); + let pauli = self.pauli_from_measurement_nodes(&meas_nodes); + let idx = self.annotations.len(); + self.annotations.push(PauliAnnotation { + pauli, + kind: AnnotationKind::Detector { + measurement_nodes: meas_nodes, + coords: Vec::new(), + }, + label: Some(label.to_string()), + }); + idx + } + + /// Annotate a detector with coordinates. + pub fn detector_with_coords( + &mut self, + measurements: &[impl Into + Copy], + coords: &[f64], + ) -> usize { + let meas_nodes: Vec = measurements.iter().map(|&m| m.into()).collect(); + let pauli = self.pauli_from_measurement_nodes(&meas_nodes); + let idx = self.annotations.len(); + self.annotations.push(PauliAnnotation { + pauli, + kind: AnnotationKind::Detector { + measurement_nodes: meas_nodes, + coords: coords.to_vec(), + }, + label: None, + }); + idx + } + + /// Annotate a logical observable: a set of measurements whose XOR + /// defines whether a logical operator flipped. + /// + /// The Pauli string is automatically Z on the measured qubits. + /// + /// Returns the annotation index. + pub fn observable(&mut self, measurements: &[impl Into + Copy]) -> usize { + let meas_nodes: Vec = measurements.iter().map(|&m| m.into()).collect(); + let pauli = self.pauli_from_measurement_nodes(&meas_nodes); + let idx = self.annotations.len(); + self.annotations.push(PauliAnnotation { + pauli, + kind: AnnotationKind::Observable { + measurement_nodes: meas_nodes, + }, + label: None, + }); + idx + } + + /// Annotate a labeled observable. + pub fn observable_labeled( + &mut self, + label: &str, + measurements: &[impl Into + Copy], + ) -> usize { + let meas_nodes: Vec = measurements.iter().map(|&m| m.into()).collect(); + let pauli = self.pauli_from_measurement_nodes(&meas_nodes); + let idx = self.annotations.len(); + self.annotations.push(PauliAnnotation { + pauli, + kind: AnnotationKind::Observable { + measurement_nodes: meas_nodes, + }, + label: Some(label.to_string()), + }); + idx + } + + /// Derive a `PauliString` from measurement nodes. + /// Z-basis measurements → Z on the measured qubit. + fn pauli_from_measurement_nodes(&self, nodes: &[usize]) -> pecos_core::PauliString { + let qubits: Vec = nodes + .iter() + .filter_map(|&node| { + let gate = self.gate(node)?; + Some(gate.qubits.iter().map(pecos_core::QubitId::index)) + }) + .flatten() + .collect(); + pecos_core::PauliString::zs(&qubits) + } + + /// Place a Pauli operator meta-gate at this point in the circuit. + /// + /// This is a **positional** annotation: only faults BEFORE this node + /// can flip the operator. The meta-gate does not affect quantum state + /// -- simulators ignore it. + /// + /// Accepts a [`PauliString`](pecos_core::PauliString), which supports + /// the `X(q) & Y(q) & Z(q)` composition syntax. + /// + /// Returns the annotation index. + /// + /// # Example + /// ``` + /// use pecos_quantum::DagCircuit; + /// use pecos_core::pauli::constructors::{X, Z}; + /// + /// let mut c = DagCircuit::new(); + /// c.pz(&[0, 1, 2]); + /// c.cx(&[(0, 1)]); + /// // Place X_0 & Z_1 & Z_2 check HERE -- only faults above can flip it + /// c.pauli_operator(X(0) & Z(1) & Z(2)); + /// c.cx(&[(1, 2)]); // faults here don't affect the check + /// ``` + pub fn pauli_operator(&mut self, mut pauli: pecos_core::PauliString) -> usize { + // Phase is irrelevant for flip tracking -- normalize to +1 + pauli.set_phase(pecos_core::QuarterPhase::PlusOne); + let idx = self.annotations.len(); + self.insert_pauli_meta_gate(&pauli); + self.annotations.push(PauliAnnotation { + pauli, + kind: AnnotationKind::Operator, + label: None, + }); + idx + } + + /// Place a labeled Pauli operator meta-gate. + pub fn pauli_operator_labeled( + &mut self, + label: &str, + mut pauli: pecos_core::PauliString, + ) -> usize { + pauli.set_phase(pecos_core::QuarterPhase::PlusOne); + let idx = self.annotations.len(); + self.insert_pauli_meta_gate(&pauli); + self.annotations.push(PauliAnnotation { + pauli, + kind: AnnotationKind::Operator, + label: Some(label.to_string()), + }); + idx + } + + /// Insert a `PauliOperatorMeta` gate node into the DAG. + fn insert_pauli_meta_gate(&mut self, pauli: &pecos_core::PauliString) { + let qubits: Vec = pauli.qubits().into_iter().map(QubitId::from).collect(); + let gate = Gate::simple(GateType::PauliOperatorMeta, qubits); + self.add_gate_auto_wire(gate); + } + + /// Get all annotations. + #[must_use] + pub fn annotations(&self) -> &[PauliAnnotation] { + &self.annotations + } + + /// Add a pre-built annotation (used for conversion from `TickCircuit`). + pub fn add_annotation(&mut self, ann: PauliAnnotation) { + // For Operator annotations, insert the meta-gate node + if matches!(ann.kind, AnnotationKind::Operator) { + self.insert_pauli_meta_gate(&ann.pauli); + } + self.annotations.push(ann); + } + + /// Get detector annotations. + pub fn detectors(&self) -> impl Iterator { + self.annotations + .iter() + .filter(|a| matches!(a.kind, AnnotationKind::Detector { .. })) + } + + /// Get observable annotations. + pub fn observables(&self) -> impl Iterator { + self.annotations + .iter() + .filter(|a| matches!(a.kind, AnnotationKind::Observable { .. })) + } + + /// Get tracked Pauli operator annotations. + pub fn pauli_operators(&self) -> impl Iterator { + self.annotations + .iter() + .filter(|a| matches!(a.kind, AnnotationKind::Operator)) + } + + // ======================================================================== + // Preparation Gates + // ======================================================================== + /// Prepare qubit(s) in the |0> state (Z-basis preparation). pub fn pz(&mut self, qubits: &[impl Into + Copy]) -> &mut Self { for &q in qubits { @@ -2404,10 +2659,9 @@ mod tests { .cx(&[(0, 1)]) .meta("fidelity", Attribute::Float(0.99)); - // Chain meta directly from measurement (mz returns &mut Self) - circuit - .mz(&[0]) - .meta("basis", Attribute::String("Z".to_string())); + // Measurement returns node indices; use last_node for meta + circuit.mz(&[0]); + circuit.meta("basis", Attribute::String("Z".to_string())); assert_eq!(circuit.gate_count(), 3); @@ -2449,22 +2703,21 @@ mod tests { } #[test] - fn test_measure_handle_drops_cleanly() { + fn test_mz_returns_refs() { let mut circuit = DagCircuit::new(); - // MeasureHandle can be ignored (dropped without calling .meta()) circuit.h(&[0]); - circuit.mz(&[0]); + let refs = circuit.mz(&[0]); + assert_eq!(refs.len(), 1); circuit.h(&[1]); // continue building assert_eq!(circuit.gate_count(), 3); } #[test] - fn test_prep_handle_drops_cleanly() { + fn test_pz_chainable() { let mut circuit = DagCircuit::new(); - // PrepHandle can be ignored (dropped without calling .meta()) circuit.pz(&[0]); circuit.h(&[0]); // continue building circuit.mz(&[0]); diff --git a/crates/pecos-quantum/src/lib.rs b/crates/pecos-quantum/src/lib.rs index 949583ce1..9d29a3672 100644 --- a/crates/pecos-quantum/src/lib.rs +++ b/crates/pecos-quantum/src/lib.rs @@ -80,11 +80,12 @@ pub mod hugr_convert; pub use circuit::{Circuit, CircuitMut, GateHandle, GateView}; pub use dag_circuit::{ - Attribute, DagCircuit, DagTraversalIndex, MeasureHandle, PrepHandle, TraversalWorkBuffers, + AnnotationKind, Attribute, DagCircuit, DagTraversalIndex, MeasRef, PauliAnnotation, + TraversalWorkBuffers, }; pub use tick_circuit::{ CustomGateError, GateSignatureMismatchError, QubitConflictError, Tick, TickCircuit, TickHandle, - TickMeasureHandle, TickPrepHandle, + TickMeasRef, TickMeasureHandle, TickPrepHandle, }; pub use tick_circuit_soa::{ CircuitIndexes, GateBatch, GateId, GateStorage, MetadataStorage, TickBatches, TickCircuitSoA, diff --git a/crates/pecos-quantum/src/pass.rs b/crates/pecos-quantum/src/pass.rs index 5a74a703f..4bb771957 100644 --- a/crates/pecos-quantum/src/pass.rs +++ b/crates/pecos-quantum/src/pass.rs @@ -26,13 +26,104 @@ use pecos_core::{Angle64, Gate, GateQubits, QubitId}; use crate::{Attribute, DagCircuit, TickCircuit}; /// A transformation pass that can be applied to circuits. +/// +/// Passes transform circuits in-place. For a copy, clone the circuit first: +/// +/// ```no_run +/// # use pecos_quantum::pass::{CircuitPass, SimplifyRotations}; +/// # use pecos_quantum::TickCircuit; +/// # let circuit = TickCircuit::new(); +/// // In-place +/// let mut tc = circuit; +/// SimplifyRotations.apply_tick(&mut tc); +/// +/// // Copy (clone first) +/// # let original = TickCircuit::new(); +/// let transformed = SimplifyRotations.transform_tick(original); +/// ``` pub trait CircuitPass { - /// Apply this pass to a [`TickCircuit`]. + /// Apply this pass to a [`TickCircuit`] in-place. fn apply_tick(&self, circuit: &mut TickCircuit); - /// Apply this pass to a [`DagCircuit`]. + + /// Apply this pass to a [`DagCircuit`] in-place. fn apply_dag(&self, circuit: &mut DagCircuit); + + /// Take ownership, transform, return. + fn transform_tick(&self, mut circuit: TickCircuit) -> TickCircuit { + self.apply_tick(&mut circuit); + circuit + } + + /// Take ownership, transform, return. + fn transform_dag(&self, mut circuit: DagCircuit) -> DagCircuit { + self.apply_dag(&mut circuit); + circuit + } +} + +// ============================================================================ +// Free functions: primary user-facing pass API +// ============================================================================ + +/// Lower Clifford-angle rotations to named Clifford gates. +/// +/// RZ(pi/2) -> SZ, RZ(pi) -> Z, RX(pi/2) -> SX, etc. +/// Also decomposes two-qubit rotations: RZZ(pi) -> Z+Z. +pub fn lower_clifford_rotations(circuit: &mut TickCircuit) { + SimplifyRotations.apply_tick(circuit); +} + +/// Insert Idle gates after each two-qubit gate on both of its qubits. +/// +/// Adds Idle(duration) on both qubits of each 2q gate. Models idle noise +/// during 2q gate execution. +pub fn insert_idle_after_two_qubit_gates(circuit: &mut TickCircuit, duration: f64) { + InsertIdleAfterTwoQubitGates(duration).apply_tick(circuit); +} + +/// Remove identity gates (I, Idle, zero-angle rotations). +pub fn remove_identity(circuit: &mut TickCircuit) { + RemoveIdentity.apply_tick(circuit); +} + +/// Cancel adjacent inverse gate pairs (H-H, S-Sdg, T-Tdg, etc.). +pub fn cancel_inverses(circuit: &mut TickCircuit) { + CancelInverses.apply_tick(circuit); +} + +/// Merge adjacent rotations on the same qubit into a single rotation. +pub fn merge_adjacent_rotations(circuit: &mut TickCircuit) { + MergeAdjacentRotations.apply_tick(circuit); +} + +/// Peephole optimization (rotation merging + Clifford lowering). +pub fn peephole_optimize(circuit: &mut TickCircuit) { + PeepholeOptimize.apply_tick(circuit); } +/// Absorb single-qubit basis gates into adjacent preps/measurements. +pub fn absorb_basis_gates(circuit: &mut TickCircuit) { + AbsorbBasisGates.apply_tick(circuit); +} + +/// Compact ticks by ASAP scheduling (merge gates into earlier ticks). +pub fn compact_ticks(circuit: &mut TickCircuit) { + CompactTicks.apply_tick(circuit); +} + +/// Assign MeasId to measurement gates that don't have them. +/// +/// Walks the circuit in tick order and assigns sequential MeasIds +/// to any MZ/MeasureFree gate with empty `meas_ids`. Existing MeasIds +/// are preserved. New IDs continue from the circuit's current counter. +pub fn assign_missing_meas_ids(circuit: &mut TickCircuit) { + AssignMissingMeasIds.apply_tick(circuit); +} + +// ============================================================================ +// Pass trait and pipeline +// ============================================================================ + /// An ordered collection of passes applied sequentially. /// /// `PassPipeline` itself implements [`CircuitPass`], so pipelines can be @@ -122,9 +213,70 @@ impl CircuitPass for PassPipeline { /// | RYY | pi | Y + Y | pub struct SimplifyRotations; +/// Insert Idle gates after each two-qubit gate on both of its qubits. +/// +/// For each tick containing two-qubit gates, adds a new tick immediately +/// after with `Idle(duration)` on each qubit involved in a two-qubit gate. +/// +/// This models the idle noise that qubits experience during two-qubit +/// gate execution. The noise model applies `RZ(p_idle * duration)` when +/// it encounters an Idle gate. +/// +/// The inner value is the idle duration in time units (typically 1.0). +pub struct InsertIdleAfterTwoQubitGates(pub f64); + +impl CircuitPass for InsertIdleAfterTwoQubitGates { + fn apply_tick(&self, circuit: &mut TickCircuit) { + let duration = self.0; + let mut new_ticks = Vec::with_capacity(circuit.ticks().len() * 2); + + // Drain ticks from circuit and rebuild with idle insertions + let old_ticks: Vec<_> = std::mem::take(circuit.ticks_vec_mut()); + + for tick in old_ticks { + let mut idle_qubits: Vec = Vec::new(); + for gate in tick.gates() { + if gate.is_two_qubit() { + for q in &gate.qubits { + if !idle_qubits.contains(q) { + idle_qubits.push(*q); + } + } + } + } + + new_ticks.push(tick); + + if !idle_qubits.is_empty() { + let mut idle_tick = crate::Tick::new(); + for q in idle_qubits { + idle_tick.add_gate(Gate::idle(duration, vec![q])); + } + new_ticks.push(idle_tick); + } + } + + *circuit.ticks_vec_mut() = new_ticks; + } + + fn apply_dag(&self, _circuit: &mut DagCircuit) { + // DAG doesn't have tick structure — no-op + } +} + /// Apply an in-place simplification to a gate. Returns `true` if the gate was /// simplified (either renamed in place or needs decomposition handling). fn simplify_gate_in_place(gate: &mut Gate) -> bool { + // R1XY has two angles — handle separately + if gate.gate_type == GateType::R1XY && gate.angles.len() == 2 { + if let Some(named) = pecos_core::try_simplify_r1xy(gate.angles[0], gate.angles[1]) { + gate.gate_type = named; + gate.angles.clear(); + return true; + } + return false; + } + if gate.angles.len() != 1 { return false; } @@ -582,10 +734,7 @@ impl CircuitPass for MergeAdjacentRotations { fn apply_dag(&self, circuit: &mut DagCircuit) { let topo = circuit.topological_order(); for node in topo { - loop { - let Some(gate) = circuit.gate(node) else { - break; - }; + while let Some(gate) = circuit.gate(node) { if !is_rotation(gate.gate_type) || gate.angles.len() != 1 { break; } @@ -1035,6 +1184,41 @@ impl CircuitPass for CompactTicks { } } +/// Assign [`MeasId`](pecos_core::MeasId) to measurement gates that don't have them. +/// +/// Walks the circuit in tick order and assigns sequential IDs to any +/// measurement gate with empty `meas_ids`. Existing IDs are preserved. +/// New IDs continue from the circuit's current measurement counter. +/// +/// Use this on circuits from external sources (QIS trace, Stim import) +/// that don't assign MeasId during construction. +pub struct AssignMissingMeasIds; + +impl CircuitPass for AssignMissingMeasIds { + fn apply_tick(&self, circuit: &mut TickCircuit) { + let mut next_id = circuit.num_measurements(); + for tick in circuit.ticks_mut() { + for gate in tick.gates_mut() { + let is_measurement = matches!(gate.gate_type, GateType::MZ | GateType::MeasureFree); + if is_measurement && gate.meas_ids.is_empty() { + for _ in gate.qubits.iter() { + gate.meas_ids.push(pecos_core::MeasId(next_id)); + next_id += 1; + } + } + } + } + let added = next_id - circuit.num_measurements(); + if added > 0 { + circuit.advance_meas_counter(added); + } + } + + fn apply_dag(&self, _circuit: &mut DagCircuit) { + // No-op: DagCircuit gates are accessed differently. + } +} + #[cfg(test)] #[allow(clippy::cast_precision_loss)] mod tests { diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index 8b65edeba..2858bd12b 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -40,9 +40,11 @@ //! //! assert_eq!(circuit.num_ticks(), 6); //! -//! // Preps and measurements break the chain but allow .meta(): +//! // Preps break the chain but allow .meta(): //! circuit.tick().pz(&[0]).meta("reason", pecos_quantum::Attribute::String("init".into())); -//! circuit.tick().mz(&[0]).meta("basis", pecos_quantum::Attribute::String("Z".into())); +//! // Measurements return refs for annotations: +//! let ms = circuit.tick().mz(&[0]); +//! circuit.detector(&ms); //! //! // Tick-level metadata: call meta() before adding gates //! use pecos_quantum::Attribute; @@ -61,11 +63,13 @@ //! ``` use pecos_core::gate_type::GateType; -use pecos_core::{Angle64, Gate, GateQubits, GateSignature, QubitId, TimeUnits}; -use std::collections::{BTreeMap, BTreeSet, HashMap}; +use pecos_core::{ + Angle64, Gate, GateMeasIds, GateQubits, GateSignature, MeasId, QubitId, TimeUnits, +}; +use std::collections::{BTreeMap, BTreeSet}; use crate::Attribute; -use crate::dag_circuit::DagCircuit; +use crate::dag_circuit::{AnnotationKind, DagCircuit, PauliAnnotation}; use std::fmt; /// Error when trying to add a gate that uses a qubit already in use in this tick. @@ -425,6 +429,23 @@ impl Tick { /// circuit.tick().cx(&[(0, 1), (2, 3)]); // Multiple CX gates /// circuit.tick().mz(&[0, 1, 2, 3]); // Measure multiple qubits /// ``` +/// Measurement reference in a tick circuit: (`tick_index`, `gate_index`, qubit). +/// +/// Returned by `mz()` for use in `detector()` and `observable()` annotations. +#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] +pub struct TickMeasRef { + /// Tick index. + pub tick: usize, + /// Gate index within the tick. + pub gate_idx: usize, + /// Qubit that was measured. + pub qubit: QubitId, + /// Measurement record index (cumulative count of MZ qubits in circuit order). + pub record_idx: usize, + /// Stable measurement result identity (SSA value). + pub meas_id: MeasId, +} + #[derive(Debug, Clone, Default)] pub struct TickCircuit { /// The sequence of ticks. @@ -434,7 +455,11 @@ pub struct TickCircuit { /// Circuit-level metadata. circuit_attrs: BTreeMap, /// Gate signatures for custom gate validation (JIT + AOT). - gate_signatures: HashMap, + gate_signatures: BTreeMap, + /// Unified Pauli annotations (detectors, observables, operators). + annotations: Vec, + /// Running count of measurement records (incremented by each MZ qubit). + next_meas_record: usize, } /// Handle to a specific tick for adding gates. @@ -515,7 +540,9 @@ impl TickCircuit { ticks: Vec::new(), next_tick: 0, circuit_attrs: BTreeMap::new(), - gate_signatures: HashMap::new(), + gate_signatures: BTreeMap::new(), + annotations: Vec::new(), + next_meas_record: 0, } } @@ -525,12 +552,31 @@ impl TickCircuit { self.ticks.len() } + /// Total number of measurement results produced so far. + #[must_use] + pub fn num_measurements(&self) -> usize { + self.next_meas_record + } + + /// Advance the measurement counter by `n` (for external MZ gate construction). + pub fn advance_meas_counter(&mut self, n: usize) { + self.next_meas_record += n; + } + /// Get the total number of gates across all ticks. #[must_use] pub fn gate_count(&self) -> usize { self.ticks.iter().map(Tick::len).sum() } + /// Convert a per-tick gate index to a global gate index. + /// + /// Global index = sum of gate counts for all ticks before `tick_idx` + `gate_idx`. + #[must_use] + pub fn global_gate_index(&self, tick_idx: usize, gate_idx: usize) -> usize { + self.ticks[..tick_idx].iter().map(Tick::len).sum::() + gate_idx + } + /// Get a tick by index. #[must_use] pub fn get_tick(&self, idx: usize) -> Option<&Tick> { @@ -548,11 +594,17 @@ impl TickCircuit { &self.ticks } - /// Get mutable access to all ticks. + /// Get mutable access to all ticks (slice). pub fn ticks_mut(&mut self) -> &mut [Tick] { &mut self.ticks } + /// Get mutable access to the ticks vector (for structural passes that + /// need to insert/remove ticks). + pub fn ticks_vec_mut(&mut self) -> &mut Vec { + &mut self.ticks + } + /// Export as a plain ASCII circuit diagram. /// /// Produces horizontal qubit-wire lines with gate symbols placed at each @@ -896,14 +948,14 @@ impl TickCircuit { // --- Gate signature validation --- /// Import gate signatures in bulk (e.g., from a `GateRegistry`). - pub fn import_signatures(&mut self, sigs: &HashMap) { + pub fn import_signatures(&mut self, sigs: &BTreeMap) { self.gate_signatures .extend(sigs.iter().map(|(name, sig)| (name.clone(), sig.clone()))); } /// Get read access to the gate signatures. #[must_use] - pub fn gate_signatures(&self) -> &HashMap { + pub fn gate_signatures(&self) -> &BTreeMap { &self.gate_signatures } @@ -1075,6 +1127,221 @@ impl TickCircuit { } counts } + // ==================== Annotations ==================== + + /// Annotate a detector: measurements whose XOR should be deterministic. + pub fn detector(&mut self, measurements: &[TickMeasRef]) -> usize { + let meas_nodes: Vec = measurements.iter().map(|m| m.record_idx).collect(); + let pauli = pecos_core::PauliString::zs( + &measurements + .iter() + .map(|m| m.qubit.index()) + .collect::>(), + ); + let idx = self.annotations.len(); + self.annotations.push(PauliAnnotation { + pauli, + kind: AnnotationKind::Detector { + measurement_nodes: meas_nodes, + coords: Vec::new(), + }, + label: None, + }); + idx + } + + /// Annotate a labeled detector. + pub fn detector_labeled(&mut self, label: &str, measurements: &[TickMeasRef]) -> usize { + let idx = self.detector(measurements); + self.annotations[idx].label = Some(label.to_string()); + idx + } + + /// Annotate a logical observable. + pub fn observable(&mut self, measurements: &[TickMeasRef]) -> usize { + let meas_nodes: Vec = measurements.iter().map(|m| m.record_idx).collect(); + let pauli = pecos_core::PauliString::zs( + &measurements + .iter() + .map(|m| m.qubit.index()) + .collect::>(), + ); + let idx = self.annotations.len(); + self.annotations.push(PauliAnnotation { + pauli, + kind: AnnotationKind::Observable { + measurement_nodes: meas_nodes, + }, + label: None, + }); + idx + } + + /// Annotate a labeled observable. + pub fn observable_labeled(&mut self, label: &str, measurements: &[TickMeasRef]) -> usize { + let idx = self.observable(measurements); + self.annotations[idx].label = Some(label.to_string()); + idx + } + + /// Place a Pauli operator annotation. + pub fn pauli_operator(&mut self, mut pauli: pecos_core::PauliString) -> usize { + pauli.set_phase(pecos_core::QuarterPhase::PlusOne); + let idx = self.annotations.len(); + self.annotations.push(PauliAnnotation { + pauli, + kind: AnnotationKind::Operator, + label: None, + }); + idx + } + + /// Place a labeled Pauli operator annotation. + pub fn pauli_operator_labeled(&mut self, label: &str, pauli: pecos_core::PauliString) -> usize { + let idx = self.pauli_operator(pauli); + self.annotations[idx].label = Some(label.to_string()); + idx + } + + /// Get all annotations. + #[must_use] + pub fn annotations(&self) -> &[PauliAnnotation] { + &self.annotations + } + + // ==================== Idle ==================== + + /// Insert identity gates for qubits not operated on during each tick. + /// + /// For each tick, finds qubits that are in the circuit's qubit set but + /// not actively operated on, and inserts an identity (I) gate. These + /// gates receive `p1` noise from the noise model, matching Stim's + /// convention of `DEPOLARIZE1` on idle qubits between ticks. + /// + /// This is separate from `GateType::Idle` which represents explicit + /// wait operations with duration-dependent `p_idle` noise. + /// + /// # Example + /// + /// ``` + /// use pecos_quantum::TickCircuit; + /// + /// let mut circuit = TickCircuit::new(); + /// circuit.tick().h(&[0]); + /// circuit.tick().cx(&[(0, 1)]); + /// circuit.tick().mz(&[0, 1]); + /// + /// circuit.fill_idle_gates(); + /// ``` + /// Insert Idle gates after each two-qubit gate on both of its qubits. + /// + /// Delegates to `InsertIdleAfterTwoQubitGates` pass. See [`crate::pass`]. + pub fn insert_idle_after_two_qubit_gates(&mut self, duration: f64) { + use crate::pass::{CircuitPass, InsertIdleAfterTwoQubitGates}; + InsertIdleAfterTwoQubitGates(duration).apply_tick(self); + } + + pub fn fill_idle_gates(&mut self) { + let all_qubits = self.all_qubits(); + if all_qubits.is_empty() { + return; + } + + for tick in &mut self.ticks { + let active = tick.active_qubits(); + for &q in &all_qubits { + if !active.contains(&q) { + // Duration 1 = one tick of idling + let _ = tick.try_add_gate(Gate::idle(1.0, vec![q])); + } + } + } + } + + /// Compact ticks by merging gates into earlier ticks when possible. + /// + /// ASAP scheduling: walk ticks in order, try to merge each tick's gates + /// into the latest tick where all qubits are free. Produces the minimum + /// number of ticks for the same gate dependency structure. + /// + /// This is useful after replaying a serialized trace (e.g., from QIR) + /// where each gate gets its own tick even if they could run in parallel. + /// + /// Gate metadata and tick-level metadata are preserved. Tick-level + /// metadata from merged ticks is dropped (the target tick's metadata + /// wins). + /// + /// # Example + /// + /// ``` + /// use pecos_quantum::TickCircuit; + /// + /// let mut circuit = TickCircuit::new(); + /// // Serialized: each gate in its own tick + /// circuit.tick().h(&[0]); + /// circuit.tick().h(&[1]); + /// circuit.tick().cx(&[(0, 1)]); + /// assert_eq!(circuit.num_ticks(), 3); + /// + /// circuit.compact_ticks(); + /// // H(0) and H(1) merged into one tick; CX(0,1) stays separate + /// assert_eq!(circuit.num_ticks(), 2); + /// ``` + pub fn compact_ticks(&mut self) { + if self.ticks.len() <= 1 { + return; + } + + let old_ticks: Vec = self.ticks.drain(..).collect(); + let mut compacted: Vec = Vec::new(); + + for tick in old_ticks { + let mut placed = false; + + // Try to merge into the latest existing tick where all qubits are free. + // Walk backwards to find the latest valid target (ASAP scheduling). + for target_idx in (0..compacted.len()).rev() { + let can_merge = tick.gates.iter().all(|gate| { + gate.qubits + .iter() + .all(|q| !compacted[target_idx].uses_qubit(*q)) + }); + + if can_merge { + // Check that no tick between target+1..end uses any of these qubits + // (would violate ordering). + let all_clear = (target_idx + 1..compacted.len()).all(|between| { + tick.gates.iter().all(|gate| { + gate.qubits + .iter() + .all(|q| !compacted[between].uses_qubit(*q)) + }) + }); + + if all_clear { + // Move gates and their per-gate metadata into the target tick. + for (gi, gate) in tick.gates.iter().enumerate() { + let new_idx = compacted[target_idx].add_gate(gate.clone()); + if let Some(attrs) = tick.gate_attrs.get(&gi) { + compacted[target_idx] + .gate_attrs + .insert(new_idx, attrs.clone()); + } + } + placed = true; + break; + } + } + } + + if !placed { + compacted.push(tick); + } + } + + self.ticks = compacted; + self.next_tick = self.ticks.len(); + } } // --- TickHandle - handle for adding gates to a specific tick --- @@ -1613,13 +1880,32 @@ impl<'a> TickHandle<'a> { /// circuit.tick().mz(&[0]); // Single qubit /// circuit.tick().mz(&[1, 2, 3]); // Multiple qubits /// ``` - pub fn mz(mut self, qubits: &[impl Into + Copy]) -> TickMeasureHandle<'a> { - let gate_idx = self.add_gate_get_idx(Gate::mz(qubits)); - TickMeasureHandle { - circuit: self.circuit, - tick_idx: self.tick_idx, - gate_idx, - } + pub fn mz(mut self, qubits: &[impl Into + Copy]) -> Vec { + let mut gate = Gate::mz(qubits); + let refs: Vec = qubits + .iter() + .map(|&q| { + let record_idx = self.circuit.next_meas_record; + let mr = MeasId(record_idx); + self.circuit.next_meas_record += 1; + gate.meas_ids.push(mr); + TickMeasRef { + tick: self.tick_idx, + gate_idx: 0, // placeholder, updated below + qubit: q.into(), + record_idx, + meas_id: mr, + } + }) + .collect(); + let gate_idx = self.add_gate_get_idx(gate); + // Fix up gate_idx in refs (needed because we had to build gate before adding) + refs.into_iter() + .map(|mut r| { + r.gate_idx = gate_idx; + r + }) + .collect() } /// Measure and free qubit(s) (destructive measurement). @@ -1634,13 +1920,31 @@ impl<'a> TickHandle<'a> { /// let mut circuit = TickCircuit::new(); /// circuit.tick().mz_free(&[0, 1]); /// ``` - pub fn mz_free(mut self, qubits: &[impl Into + Copy]) -> TickMeasureHandle<'a> { - let gate_idx = self.add_gate_get_idx(Gate::mz_free(qubits)); - TickMeasureHandle { - circuit: self.circuit, - tick_idx: self.tick_idx, - gate_idx, - } + pub fn mz_free(mut self, qubits: &[impl Into + Copy]) -> Vec { + let mut gate = Gate::mz_free(qubits); + let refs: Vec = qubits + .iter() + .map(|&q| { + let record_idx = self.circuit.next_meas_record; + let mr = MeasId(record_idx); + self.circuit.next_meas_record += 1; + gate.meas_ids.push(mr); + TickMeasRef { + tick: self.tick_idx, + gate_idx: 0, + qubit: q.into(), + record_idx, + meas_id: mr, + } + }) + .collect(); + let gate_idx = self.add_gate_get_idx(gate); + refs.into_iter() + .map(|mut r| { + r.gate_idx = gate_idx; + r + }) + .collect() } // --- Resource management --- @@ -1788,7 +2092,6 @@ impl From<&DagCircuit> for TickCircuit { let tick_attr_prefix = "tick["; for (key, value) in dag.attrs() { if key.starts_with(tick_attr_prefix) { - // Parse tick[N].attr_name format if let Some(rest) = key.strip_prefix(tick_attr_prefix) && let Some(bracket_pos) = rest.find(']') && let Ok(tick_idx) = rest[..bracket_pos].parse::() @@ -1805,6 +2108,13 @@ impl From<&DagCircuit> for TickCircuit { } } + // Transfer annotations (Pauli operators don't need node remapping + // since TickCircuit stores them without node references; + // Detector/Observable measurement_nodes are DAG node IDs which + // become gate_idx values in the TickCircuit -- the mapping is + // handled by the gate ordering within ticks) + tc.annotations = dag.annotations().to_vec(); + tc } } @@ -1840,22 +2150,102 @@ impl From<&TickCircuit> for DagCircuit { // Track the last node for each qubit to connect wires let mut last_node: BTreeMap = BTreeMap::new(); + // Map measurement_record_index -> dag node for annotation transfer + let mut meas_record_to_node: BTreeMap = BTreeMap::new(); + let mut meas_record_idx = 0usize; + for (tick_idx, tick) in tc.ticks().iter().enumerate() { for (gate_idx, gate) in tick.gates().iter().enumerate() { - let node = dag.add_gate(gate.clone()); + // Split batched gates into individual operations. + // + // TickCircuit batches gates for efficiency: + // - 1q gates: H([0,1,2]) = one gate with 3 qubits + // - 2q gates: CX([0,1, 2,3]) = one gate with 4 qubits (2 pairs) + // + // DagCircuit needs individual gates for correct fault analysis. + // Without splitting, a 4-qubit MZ generates 2^4-1=15 fault combos + // instead of 4 independent X faults. A 12-qubit CX generates + // 4^12=16M combos instead of 6×15=90. + let is_two_qubit = matches!( + gate.gate_type, + GateType::CX + | GateType::CY + | GateType::CZ + | GateType::SWAP + | GateType::RXX + | GateType::RYY + | GateType::RZZ + | GateType::SXX + | GateType::SXXdg + | GateType::SYY + | GateType::SYYdg + | GateType::SZZ + | GateType::SZZdg + ); + let needs_split = if is_two_qubit { + gate.qubits.len() > 2 + } else { + gate.qubits.len() > 1 + }; + + let split_gates: Vec = if needs_split { + let chunk_size = if is_two_qubit { 2 } else { 1 }; + gate.qubits + .chunks(chunk_size) + .filter(|chunk| chunk.len() == chunk_size) + .enumerate() + .map(|(chunk_idx, qs)| { + // For measurement gates, distribute MeasId values + // to the split gates (one per qubit). + let mr = if !gate.meas_ids.is_empty() { + let start = chunk_idx * chunk_size; + gate.meas_ids + .get(start..start + chunk_size) + .map(|s| GateMeasIds::from_iter(s.iter().copied())) + .unwrap_or_default() + } else { + GateMeasIds::new() + }; + Gate { + gate_type: gate.gate_type, + qubits: GateQubits::from_iter(qs.iter().copied()), + angles: gate.angles.clone(), + params: gate.params.clone(), + meas_ids: mr, + } + }) + .collect() + } else { + vec![gate.clone()] + }; + + for split_gate in &split_gates { + let node = dag.add_gate(split_gate.clone()); + + // For MZ gates, map each qubit's record to this node + if split_gate.gate_type == GateType::MZ { + for _q in &split_gate.qubits { + meas_record_to_node.insert(meas_record_idx, node); + meas_record_idx += 1; + } + } - // Connect wires from previous gates on the same qubits - for qubit in &gate.qubits { - if let Some(&prev_node) = last_node.get(qubit) { - // Connect previous node to this one on this qubit - let _ = dag.connect(prev_node, node, *qubit); + // Connect wires from previous gates on the same qubits + for qubit in &split_gate.qubits { + if let Some(&prev_node) = last_node.get(qubit) { + let _ = dag.connect(prev_node, node, *qubit); + } + last_node.insert(*qubit, node); } - last_node.insert(*qubit, node); } - // Copy gate attributes + // Copy gate attributes (applied to last split gate) for (key, value) in tick.gate_attrs(gate_idx) { - dag.set_gate_attr(node, key, value.clone()); + if let Some(split_gate) = split_gates.last() { + let last_node_id = + *last_node.get(split_gate.qubits.first().unwrap()).unwrap(); + dag.set_gate_attr(last_node_id, key, value.clone()); + } } } @@ -1871,6 +2261,40 @@ impl From<&TickCircuit> for DagCircuit { dag.set_attr(key.clone(), value.clone()); } + // Transfer annotations, remapping measurement record indices to DAG node indices + for ann in &tc.annotations { + let remapped_kind = match &ann.kind { + AnnotationKind::Detector { + measurement_nodes, + coords, + } => { + let dag_nodes: Vec = measurement_nodes + .iter() + .filter_map(|&rec| meas_record_to_node.get(&rec).copied()) + .collect(); + AnnotationKind::Detector { + measurement_nodes: dag_nodes, + coords: coords.clone(), + } + } + AnnotationKind::Observable { measurement_nodes } => { + let dag_nodes: Vec = measurement_nodes + .iter() + .filter_map(|&rec| meas_record_to_node.get(&rec).copied()) + .collect(); + AnnotationKind::Observable { + measurement_nodes: dag_nodes, + } + } + AnnotationKind::Operator => AnnotationKind::Operator, + }; + dag.add_annotation(PauliAnnotation { + pauli: ann.pauli.clone(), + kind: remapped_kind, + label: ann.label.clone(), + }); + } + dag } } @@ -2009,9 +2433,11 @@ mod tests { .pz(&[0]) .meta("reason", Attribute::String("init".into())); tc.tick().h(&[0]); - tc.tick() - .mz(&[0]) - .meta("basis", Attribute::String("Z".into())); + tc.tick().mz(&[0]); + // Attach metadata to the measurement gate directly + tc.get_tick_mut(2) + .unwrap() + .set_gate_attr(0, "basis", Attribute::String("Z".into())); assert_eq!(tc.num_ticks(), 3); @@ -2064,6 +2490,90 @@ mod tests { ); } + #[test] + fn test_tick_to_dag_splits_batched_standard_two_qubit_cliffords_as_pairs() { + fn add_gate(tc: &mut TickCircuit, gate_type: GateType, pairs: &[(usize, usize)]) { + match gate_type { + GateType::CX => { + tc.tick().cx(pairs); + } + GateType::CY => { + tc.tick().cy(pairs); + } + GateType::CZ => { + tc.tick().cz(pairs); + } + GateType::SXX => { + tc.tick().sxx(pairs); + } + GateType::SXXdg => { + tc.tick().sxxdg(pairs); + } + GateType::SYY => { + tc.tick().syy(pairs); + } + GateType::SYYdg => { + tc.tick().syydg(pairs); + } + GateType::SZZ => { + tc.tick().szz(pairs); + } + GateType::SZZdg => { + tc.tick().szzdg(pairs); + } + GateType::SWAP => { + tc.tick().swap(pairs); + } + _ => unreachable!(), + } + } + + let pair_sets = [ + [(0usize, 1usize), (2usize, 3usize)], + [(4usize, 1usize), (9usize, 2usize)], + ]; + + for gate_type in [ + GateType::CX, + GateType::CY, + GateType::CZ, + GateType::SXX, + GateType::SXXdg, + GateType::SYY, + GateType::SYYdg, + GateType::SZZ, + GateType::SZZdg, + GateType::SWAP, + ] { + for pairs in pair_sets { + let mut tc = TickCircuit::new(); + add_gate(&mut tc, gate_type, &pairs); + + let dag = DagCircuit::from(&tc); + let gates: Vec<_> = dag.iter_gates().map(|(_, gate)| gate).collect(); + assert_eq!(gates.len(), 2, "{gate_type:?} {pairs:?}"); + assert!( + gates.iter().all(|gate| gate.gate_type == gate_type), + "{gate_type:?} {pairs:?}" + ); + assert!( + gates.iter().all(|gate| gate.qubits.len() == 2), + "{gate_type:?} should remain pairwise in the DAG for {pairs:?}" + ); + for (q0, q1) in pairs { + assert!( + gates.iter().any(|gate| gate + .qubits + .iter() + .copied() + .eq([QubitId(q0), QubitId(q1)])), + "{gate_type:?} should preserve pair ({q0}, {q1})" + ); + } + } + } + } + #[test] fn test_dag_circuit_to_tick_circuit() { let mut dag = DagCircuit::new(); @@ -2753,7 +3263,7 @@ mod tests { #[test] fn test_import_signatures() { let mut tc = TickCircuit::new(); - let mut sigs = HashMap::new(); + let mut sigs = BTreeMap::new(); sigs.insert( "AOT_GATE".to_string(), GateSignature { @@ -2786,4 +3296,216 @@ mod tests { tc.reset(); assert!(tc.gate_signatures().is_empty()); } + + #[test] + fn test_tick_circuit_annotations() { + use pecos_core::pauli::constructors::X; + + let mut tc = TickCircuit::new(); + tc.tick().pz(&[0, 1, 2]); + tc.tick().cx(&[(0, 2), (1, 2)]); + let ms = tc.tick().mz(&[2]); + + assert_eq!(ms.len(), 1); + assert_eq!(ms[0].qubit, QubitId::from(2)); + + tc.detector_labeled("Z_check", &ms); + tc.observable_labeled("logical_Z", &ms); + tc.pauli_operator_labeled("logical_X", X(0) & X(1)); + + assert_eq!(tc.annotations().len(), 3); + assert_eq!(tc.annotations()[0].label.as_deref(), Some("Z_check")); + assert_eq!(tc.annotations()[1].label.as_deref(), Some("logical_Z")); + assert_eq!(tc.annotations()[2].label.as_deref(), Some("logical_X")); + } + + #[test] + fn test_tick_to_dag_annotation_transfer() { + use pecos_core::pauli::constructors::Z; + + let mut tc = TickCircuit::new(); + tc.tick().pz(&[0, 1, 2]); + tc.tick().cx(&[(0, 2), (1, 2)]); + let ms = tc.tick().mz(&[2]); + tc.detector_labeled("det0", &ms); + tc.observable_labeled("obs0", &ms); + tc.pauli_operator_labeled("op0", Z(0) & Z(1)); + + let dag = DagCircuit::from(&tc); + + // Annotations should transfer + assert_eq!(dag.annotations().len(), 3); + assert_eq!(dag.annotations()[0].label.as_deref(), Some("det0")); + assert_eq!(dag.annotations()[1].label.as_deref(), Some("obs0")); + assert_eq!(dag.annotations()[2].label.as_deref(), Some("op0")); + + // Kinds preserved + assert!(matches!( + dag.annotations()[0].kind, + crate::dag_circuit::AnnotationKind::Detector { .. } + )); + assert!(matches!( + dag.annotations()[1].kind, + crate::dag_circuit::AnnotationKind::Observable { .. } + )); + assert!(matches!( + dag.annotations()[2].kind, + crate::dag_circuit::AnnotationKind::Operator + )); + } + + #[test] + fn test_dag_to_tick_annotation_transfer() { + use pecos_core::pauli::constructors::X; + + let mut dag = DagCircuit::new(); + dag.pz(&[0, 1]); + dag.cx(&[(0, 1)]); + let ms = dag.mz(&[0, 1]); + dag.detector_labeled("d0", &[ms[0]]); + dag.observable_labeled("o0", &[ms[0], ms[1]]); + dag.pauli_operator_labeled("p0", X(0) & X(1)); + + let tc = TickCircuit::from(&dag); + + assert_eq!(tc.annotations().len(), 3); + assert_eq!(tc.annotations()[0].label.as_deref(), Some("d0")); + assert_eq!(tc.annotations()[1].label.as_deref(), Some("o0")); + assert_eq!(tc.annotations()[2].label.as_deref(), Some("p0")); + } + + #[test] + fn test_annotation_round_trip() { + use pecos_core::pauli::constructors::X; + + // Build TickCircuit with annotations + let mut tc1 = TickCircuit::new(); + tc1.tick().pz(&[0, 1, 2]); + tc1.tick().cx(&[(0, 2)]); + tc1.tick().cx(&[(1, 2)]); + let ms = tc1.tick().mz(&[2]); + tc1.detector_labeled("syndr", &ms); + let ms_data = tc1.tick().mz(&[0, 1]); + tc1.observable_labeled("log_Z", &ms_data); + tc1.pauli_operator_labeled("log_X", X(0) & X(1)); + + // TickCircuit -> DagCircuit -> TickCircuit + let dag = DagCircuit::from(&tc1); + let tc2 = TickCircuit::from(&dag); + + // Annotation count and labels preserved + assert_eq!(tc2.annotations().len(), tc1.annotations().len()); + for (a1, a2) in tc1.annotations().iter().zip(tc2.annotations()) { + assert_eq!(a1.label, a2.label); + assert_eq!(a1.pauli, a2.pauli); + } + } + + #[test] + fn test_mz_returns_refs() { + let mut tc = TickCircuit::new(); + tc.tick().pz(&[0, 1]); + let ms = tc.tick().mz(&[0, 1]); + + assert_eq!(ms.len(), 2); + assert_eq!(ms[0].qubit, QubitId::from(0)); + assert_eq!(ms[1].qubit, QubitId::from(1)); + // Both from same tick and gate + assert_eq!(ms[0].tick, ms[1].tick); + assert_eq!(ms[0].gate_idx, ms[1].gate_idx); + } + + #[test] + fn test_fill_idle_gates() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[0]); // qubit 1 idle + tc.tick().cx(&[(0, 1)]); // none idle + + let count_before = tc.gate_count(); + tc.fill_idle_gates(); + let count_after = tc.gate_count(); + + // Tick 0: qubit 1 was idle, should get an idle gate + assert!(count_after > count_before, "Should have added idle gates"); + } + + #[test] + fn test_meas_record_idx_single_qubit() { + let mut tc = TickCircuit::new(); + let m0 = tc.tick().mz(&[0]); + let m1 = tc.tick().mz(&[1]); + assert_eq!(m0[0].record_idx, 0); + assert_eq!(m1[0].record_idx, 1); + } + + #[test] + fn test_meas_record_idx_multi_qubit() { + let mut tc = TickCircuit::new(); + let ms = tc.tick().mz(&[0, 1, 2]); + assert_eq!(ms[0].record_idx, 0); + assert_eq!(ms[1].record_idx, 1); + assert_eq!(ms[2].record_idx, 2); + // Next measurement continues the count + let m2 = tc.tick().mz(&[3]); + assert_eq!(m2[0].record_idx, 3); + } + + #[test] + fn test_detector_uses_record_idx() { + // Two qubits measured in one gate: detector referencing each + // should get DIFFERENT record indices (not the same gate index). + let mut tc = TickCircuit::new(); + tc.tick().pz(&[0, 1]); + let ms = tc.tick().mz(&[0, 1]); + + // Detector on qubit 0's measurement + tc.detector(&[ms[0]]); + // Detector on qubit 1's measurement + tc.detector(&[ms[1]]); + + let anns = tc.annotations(); + match &anns[0].kind { + AnnotationKind::Detector { + measurement_nodes, .. + } => { + assert_eq!(measurement_nodes, &[0], "D0 should reference record 0 (q0)"); + } + _ => panic!("Expected detector"), + } + match &anns[1].kind { + AnnotationKind::Detector { + measurement_nodes, .. + } => { + assert_eq!(measurement_nodes, &[1], "D1 should reference record 1 (q1)"); + } + _ => panic!("Expected detector"), + } + } + + #[test] + fn test_detector_multi_qubit_mz_no_xor_cancel() { + // Bug regression: two refs from same multi-qubit MZ gate + // used to have the same gate_idx, causing XOR cancellation. + // With record_idx they should be distinct. + let mut tc = TickCircuit::new(); + tc.tick().pz(&[0, 1]); + let ms = tc.tick().mz(&[0, 1]); + + // Detector comparing both measurements (XOR of records 0 and 1) + tc.detector(&[ms[0], ms[1]]); + + let anns = tc.annotations(); + match &anns[0].kind { + AnnotationKind::Detector { + measurement_nodes, .. + } => { + assert_eq!(measurement_nodes.len(), 2); + assert_ne!( + measurement_nodes[0], measurement_nodes[1], + "Two qubits from same MZ must have different record indices" + ); + } + _ => panic!("Expected detector"), + } + } } diff --git a/crates/pecos-quantum/src/tick_circuit_soa.rs b/crates/pecos-quantum/src/tick_circuit_soa.rs index 5dd8dd36b..db9b5e3f0 100644 --- a/crates/pecos-quantum/src/tick_circuit_soa.rs +++ b/crates/pecos-quantum/src/tick_circuit_soa.rs @@ -143,11 +143,10 @@ impl GateBatch { #[must_use] pub fn gate_count(&self) -> usize { let arity = self.gate_type.quantum_arity(); - if arity == 0 { - self.qubits.len() - } else { - self.qubits.len() / arity - } + self.qubits + .len() + .checked_div(arity) + .unwrap_or(self.qubits.len()) } /// Returns true if the batch is empty. diff --git a/crates/pecos-quantum/src/unitary_matrix.rs b/crates/pecos-quantum/src/unitary_matrix.rs index 5a70072ae..79b873d0a 100644 --- a/crates/pecos-quantum/src/unitary_matrix.rs +++ b/crates/pecos-quantum/src/unitary_matrix.rs @@ -1834,7 +1834,8 @@ fn gate_to_matrix(gate_type: GateType, qubits: &[usize], num_qubits: usize) -> D GateType::Idle | GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload - | GateType::Custom => { + | GateType::Custom + | GateType::PauliOperatorMeta => { panic!("GateType::{gate_type:?} cannot be converted to a unitary matrix") } } diff --git a/crates/pecos-random/src/rng_manageable.rs b/crates/pecos-random/src/rng_manageable.rs index cdf54a111..29712709c 100644 --- a/crates/pecos-random/src/rng_manageable.rs +++ b/crates/pecos-random/src/rng_manageable.rs @@ -86,8 +86,7 @@ pub fn derive_seed(base_seed: u64, purpose: &str) -> u64 { pub fn time_seed() -> u64 { SystemTime::now() .duration_since(UNIX_EPOCH) - .map(|d| d.as_nanos() as u64) - .unwrap_or(12345) + .map_or(12345, |d| d.as_nanos() as u64) } /// Resolve an optional seed, using system time if none provided. diff --git a/crates/pecos-relay-bp/src/core_traits.rs b/crates/pecos-relay-bp/src/core_traits.rs index ca546425f..208eaeb43 100644 --- a/crates/pecos-relay-bp/src/core_traits.rs +++ b/crates/pecos-relay-bp/src/core_traits.rs @@ -21,6 +21,10 @@ impl DecodingResultTrait for DecodingResult { self.converged } + fn correction(&self) -> &[u8] { + self.decoding.as_slice().unwrap_or(&[]) + } + fn cost(&self) -> Option { None } diff --git a/crates/pecos-simulators/Cargo.toml b/crates/pecos-simulators/Cargo.toml index 794ce21b9..160c8dffb 100644 --- a/crates/pecos-simulators/Cargo.toml +++ b/crates/pecos-simulators/Cargo.toml @@ -18,11 +18,6 @@ default = [] # Do NOT enable for multi-shot workloads where shots are parallelized at the # orchestration level - this causes thread oversubscription and hurts throughput. parallel = ["rayon"] -# Enable AVX-512 SIMD operations using f64x8 (512-bit vectors processing 8 f64 at once). -# Requires AVX-512 capable CPU (Intel Ice Lake+, AMD Zen 4+). -# Build with: RUSTFLAGS='-C target-feature=+avx512f' cargo build --release --features avx512 -# Provides ~2x theoretical speedup for SIMD-bound operations on supported hardware. -avx512 = [] [dependencies] pecos-core.workspace = true diff --git a/crates/pecos-simulators/examples/profile_inner_product.rs b/crates/pecos-simulators/examples/profile_inner_product.rs index 0fbf55736..5cdeb95f1 100644 --- a/crates/pecos-simulators/examples/profile_inner_product.rs +++ b/crates/pecos-simulators/examples/profile_inner_product.rs @@ -1,5 +1,5 @@ use pecos_core::{Angle64, QubitId}; -use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, CliffordRz}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, StabVec}; use std::time::Instant; fn main() { @@ -13,7 +13,7 @@ fn main() { .unwrap_or(12); let theta = Angle64::from_radians(0.3); - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); diff --git a/crates/pecos-simulators/examples/profile_meas_breakdown.rs b/crates/pecos-simulators/examples/profile_meas_breakdown.rs index 71e406c6e..3610be2d2 100644 --- a/crates/pecos-simulators/examples/profile_meas_breakdown.rs +++ b/crates/pecos-simulators/examples/profile_meas_breakdown.rs @@ -1,5 +1,5 @@ use pecos_core::{Angle64, QubitId}; -use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, CliffordRz}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, StabVec}; use std::time::Instant; fn main() { @@ -13,7 +13,7 @@ fn main() { .unwrap_or(12); let theta = Angle64::from_radians(0.3); - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); // Create entangled state with many terms for q in 0..nq { diff --git a/crates/pecos-simulators/examples/profile_pruning.rs b/crates/pecos-simulators/examples/profile_pruning.rs index 29d6b89dd..db87cc869 100644 --- a/crates/pecos-simulators/examples/profile_pruning.rs +++ b/crates/pecos-simulators/examples/profile_pruning.rs @@ -1,12 +1,12 @@ use pecos_core::{Angle64, QubitId}; -use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, CliffordRz}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, StabVec}; use std::time::Instant; fn run_test(nq: usize, nrz: usize, threshold: f64) { let theta = Angle64::from_radians(0.3); let mc = if threshold < 0.0 { None } else { Some(2048) }; let actual_threshold = threshold.abs(); - let mut sim = CliffordRz::builder(nq) + let mut sim = StabVec::builder(nq) .seed(42) .pruning_threshold(actual_threshold) .mc_threshold(mc) diff --git a/crates/pecos-simulators/examples/profile_qec_like.rs b/crates/pecos-simulators/examples/profile_qec_like.rs index ebba877fd..a4f56a2ec 100644 --- a/crates/pecos-simulators/examples/profile_qec_like.rs +++ b/crates/pecos-simulators/examples/profile_qec_like.rs @@ -1,5 +1,5 @@ use pecos_core::{Angle64, QubitId}; -use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, CliffordRz}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, StabVec}; use std::time::Instant; /// QEC-like circuit: repeated rounds of gates + measurement on ancilla qubits. @@ -20,7 +20,7 @@ fn main() { let nq = data_q + ancilla_q; let theta = Angle64::from_radians(0.3); - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); // Initialize for q in 0..data_q { diff --git a/crates/pecos-simulators/examples/profile_clifford_rz.rs b/crates/pecos-simulators/examples/profile_stab_vec.rs similarity index 91% rename from crates/pecos-simulators/examples/profile_clifford_rz.rs rename to crates/pecos-simulators/examples/profile_stab_vec.rs index 0d2783cc5..649c2d346 100644 --- a/crates/pecos-simulators/examples/profile_clifford_rz.rs +++ b/crates/pecos-simulators/examples/profile_stab_vec.rs @@ -1,5 +1,5 @@ use pecos_core::{Angle64, QubitId}; -use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, CliffordRz}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, StabVec}; fn main() { let nq: usize = std::env::args() @@ -16,7 +16,7 @@ fn main() { .unwrap_or(2); let theta = Angle64::from_radians(0.3); for _ in 0..iters { - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); for q in 0..nq { sim.h(&[QubitId(q)]); } diff --git a/crates/pecos-simulators/examples/profile_terms.rs b/crates/pecos-simulators/examples/profile_terms.rs index 99c2c09e1..321887478 100644 --- a/crates/pecos-simulators/examples/profile_terms.rs +++ b/crates/pecos-simulators/examples/profile_terms.rs @@ -1,5 +1,5 @@ use pecos_core::{Angle64, QubitId}; -use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, CliffordRz}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, StabVec}; use std::time::Instant; /// Benchmark that actually creates many terms by interleaving H and RZ. @@ -14,7 +14,7 @@ fn main() { .unwrap_or(8); let theta = Angle64::from_radians(0.3); - let mut sim = CliffordRz::new_with_seed(nq, 42); + let mut sim = StabVec::new_with_seed(nq, 42); // Create entangled state for q in 0..nq { diff --git a/crates/pecos-simulators/examples/verify_mc.rs b/crates/pecos-simulators/examples/verify_mc.rs index 7c8784b93..b8eac988a 100644 --- a/crates/pecos-simulators/examples/verify_mc.rs +++ b/crates/pecos-simulators/examples/verify_mc.rs @@ -1,5 +1,5 @@ use pecos_core::{Angle64, QubitId}; -use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, CliffordRz, StateVec}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, StabVec, StateVec}; /// Verify MC sampling gives similar statistics to exact state vector. fn main() { @@ -31,12 +31,12 @@ fn main() { exact_probs[x] = state[x].norm_sqr() / norm; } - // Sample from CliffordRz (which uses MC for T > 2048, exact otherwise) + // Sample from StabVec (which uses MC for T > 2048, exact otherwise) // Force the MC path by temporarily using it let mut mc_counts = vec![0u32; dim]; #[allow(clippy::cast_sign_loss)] // num_shots is a positive literal for seed in 0..num_shots as u64 { - let mut crz = CliffordRz::new_with_seed(nq, seed); + let mut crz = StabVec::new_with_seed(nq, seed); for q in 0..nq { crz.h(&[QubitId(q)]); } @@ -79,7 +79,7 @@ fn main() { } } eprintln!("n={nq}, nrz={nrz}, T={} (exact path, not MC)", { - let mut c = CliffordRz::new(nq); + let mut c = StabVec::new(nq); for q in 0..nq { c.h(&[QubitId(q)]); } diff --git a/crates/pecos-simulators/src/clifford_gateable.rs b/crates/pecos-simulators/src/clifford_gateable.rs index 5d135f16c..8b0bf77ea 100644 --- a/crates/pecos-simulators/src/clifford_gateable.rs +++ b/crates/pecos-simulators/src/clifford_gateable.rs @@ -291,7 +291,7 @@ pub trait CliffordGateable: QuantumSimulator { /// * `&mut Self` - Returns the simulator for method chaining. #[inline] fn sy(&mut self, qubits: &[QubitId]) -> &mut Self { - self.h(qubits).x(qubits) + self.z(qubits).h(qubits) } /// Applies the adjoint (inverse) of the square root of Y gate. @@ -319,7 +319,7 @@ pub trait CliffordGateable: QuantumSimulator { /// * `&mut Self` - Returns the simulator for method chaining. #[inline] fn sydg(&mut self, qubits: &[QubitId]) -> &mut Self { - self.x(qubits).h(qubits) + self.h(qubits).z(qubits) } /// Applies a square root of Z (SZ) gate to the specified qubits. diff --git a/crates/pecos-simulators/src/clifford_matrix_oracle.rs b/crates/pecos-simulators/src/clifford_matrix_oracle.rs new file mode 100644 index 000000000..9d17c60ba --- /dev/null +++ b/crates/pecos-simulators/src/clifford_matrix_oracle.rs @@ -0,0 +1,314 @@ +// Copyright 2026 The PECOS Developers +// Licensed under the Apache License, Version 2.0 + +use num_complex::Complex64; +use std::f64::consts::FRAC_1_SQRT_2; + +#[derive(Clone, Copy, Debug)] +pub(crate) enum CliffordMatrixGate { + SZdg, + F, + Fdg, + SX, + SXdg, + SY, + SYdg, + CX, + CY, + CZ, + SXX, + SXXdg, + SYY, + SYYdg, + SZZ, + SZZdg, + SWAP, +} + +#[derive(Clone, Debug, PartialEq, Eq)] +pub(crate) struct SignedPauli { + pub(crate) sign: i8, + pub(crate) pauli: String, +} + +#[derive(Clone, Debug)] +struct Matrix { + n: usize, + data: Vec, +} + +impl Matrix { + fn from_data(n: usize, data: Vec) -> Self { + assert_eq!(data.len(), n * n); + Self { n, data } + } + + fn zeros(n: usize) -> Self { + Self { + n, + data: vec![Complex64::new(0.0, 0.0); n * n], + } + } + + fn identity(n: usize) -> Self { + let mut matrix = Self::zeros(n); + for i in 0..n { + matrix.set(i, i, Complex64::new(1.0, 0.0)); + } + matrix + } + + fn get(&self, row: usize, col: usize) -> Complex64 { + self.data[row * self.n + col] + } + + fn set(&mut self, row: usize, col: usize, value: Complex64) { + self.data[row * self.n + col] = value; + } + + fn add(&self, other: &Self) -> Self { + assert_eq!(self.n, other.n); + let data = self + .data + .iter() + .zip(other.data.iter()) + .map(|(a, b)| a + b) + .collect(); + Self::from_data(self.n, data) + } + + fn scale(&self, scalar: Complex64) -> Self { + let data = self.data.iter().map(|v| scalar * v).collect(); + Self::from_data(self.n, data) + } + + fn mul(&self, other: &Self) -> Self { + assert_eq!(self.n, other.n); + let mut out = Self::zeros(self.n); + for row in 0..self.n { + for col in 0..self.n { + let mut value = Complex64::new(0.0, 0.0); + for k in 0..self.n { + value += self.get(row, k) * other.get(k, col); + } + out.set(row, col, value); + } + } + out + } + + fn dagger(&self) -> Self { + let mut out = Self::zeros(self.n); + for row in 0..self.n { + for col in 0..self.n { + out.set(col, row, self.get(row, col).conj()); + } + } + out + } + + fn approx_eq(&self, other: &Self) -> bool { + assert_eq!(self.n, other.n); + const EPS: f64 = 1e-9; + self.data + .iter() + .zip(other.data.iter()) + .all(|(a, b)| (*a - *b).norm() < EPS) + } +} + +pub(crate) fn all_pauli_strings(num_qubits: usize) -> Vec { + let mut strings = vec![String::new()]; + for _ in 0..num_qubits { + let mut next = Vec::with_capacity(strings.len() * 4); + for prefix in &strings { + for suffix in ['I', 'X', 'Y', 'Z'] { + let mut value = prefix.clone(); + value.push(suffix); + next.push(value); + } + } + strings = next; + } + strings +} + +pub(crate) fn conjugate_pauli(gate: CliffordMatrixGate, input: &str) -> SignedPauli { + let unitary = gate_matrix(gate); + let input_matrix = pauli_string_matrix(input); + let image = unitary.mul(&input_matrix).mul(&unitary.dagger()); + classify_signed_pauli(&image, input.len()) +} + +fn classify_signed_pauli(image: &Matrix, num_qubits: usize) -> SignedPauli { + for pauli in all_pauli_strings(num_qubits) { + let matrix = pauli_string_matrix(&pauli); + if image.approx_eq(&matrix) { + return SignedPauli { sign: 1, pauli }; + } + if image.approx_eq(&matrix.scale(Complex64::new(-1.0, 0.0))) { + return SignedPauli { sign: -1, pauli }; + } + } + panic!("matrix image is not a signed Pauli"); +} + +fn gate_matrix(gate: CliffordMatrixGate) -> Matrix { + match gate { + CliffordMatrixGate::SZdg => sqrt_pauli_matrix("Z", true), + CliffordMatrixGate::F => sqrt_pauli_matrix("Z", false).mul(&sqrt_pauli_matrix("X", false)), + CliffordMatrixGate::Fdg => sqrt_pauli_matrix("X", true).mul(&sqrt_pauli_matrix("Z", true)), + CliffordMatrixGate::SX => sqrt_pauli_matrix("X", false), + CliffordMatrixGate::SXdg => sqrt_pauli_matrix("X", true), + CliffordMatrixGate::SY => sqrt_pauli_matrix("Y", false), + CliffordMatrixGate::SYdg => sqrt_pauli_matrix("Y", true), + CliffordMatrixGate::CX => controlled_x_matrix(), + CliffordMatrixGate::CY => controlled_y_matrix(), + CliffordMatrixGate::CZ => controlled_z_matrix(), + CliffordMatrixGate::SXX => sqrt_pauli_matrix("XX", false), + CliffordMatrixGate::SXXdg => sqrt_pauli_matrix("XX", true), + CliffordMatrixGate::SYY => sqrt_pauli_matrix("YY", false), + CliffordMatrixGate::SYYdg => sqrt_pauli_matrix("YY", true), + CliffordMatrixGate::SZZ => sqrt_pauli_matrix("ZZ", false), + CliffordMatrixGate::SZZdg => sqrt_pauli_matrix("ZZ", true), + CliffordMatrixGate::SWAP => swap_matrix(), + } +} + +fn sqrt_pauli_matrix(pauli: &str, adjoint: bool) -> Matrix { + let pauli = pauli_string_matrix(pauli); + let identity = Matrix::identity(pauli.n); + let phase_sign = if adjoint { 1.0 } else { -1.0 }; + identity + .scale(Complex64::new(FRAC_1_SQRT_2, 0.0)) + .add(&pauli.scale(Complex64::new(0.0, phase_sign * FRAC_1_SQRT_2))) +} + +fn pauli_string_matrix(pauli: &str) -> Matrix { + let mut matrix = Matrix::from_data(1, vec![Complex64::new(1.0, 0.0)]); + for label in pauli.chars() { + matrix = kron(&matrix, &single_pauli_matrix(label)); + } + matrix +} + +fn single_pauli_matrix(label: char) -> Matrix { + let one = Complex64::new(1.0, 0.0); + let minus_one = Complex64::new(-1.0, 0.0); + let zero = Complex64::new(0.0, 0.0); + let i = Complex64::new(0.0, 1.0); + let minus_i = Complex64::new(0.0, -1.0); + + match label { + 'I' => Matrix::from_data(2, vec![one, zero, zero, one]), + 'X' => Matrix::from_data(2, vec![zero, one, one, zero]), + 'Y' => Matrix::from_data(2, vec![zero, minus_i, i, zero]), + 'Z' => Matrix::from_data(2, vec![one, zero, zero, minus_one]), + _ => panic!("invalid Pauli label {label}"), + } +} + +fn kron(left: &Matrix, right: &Matrix) -> Matrix { + let n = left.n * right.n; + let mut out = Matrix::zeros(n); + for lr in 0..left.n { + for lc in 0..left.n { + for rr in 0..right.n { + for rc in 0..right.n { + out.set( + lr * right.n + rr, + lc * right.n + rc, + left.get(lr, lc) * right.get(rr, rc), + ); + } + } + } + } + out +} + +fn controlled_y_matrix() -> Matrix { + let one = Complex64::new(1.0, 0.0); + let zero = Complex64::new(0.0, 0.0); + let i = Complex64::new(0.0, 1.0); + let minus_i = Complex64::new(0.0, -1.0); + Matrix::from_data( + 4, + vec![ + one, zero, zero, zero, zero, one, zero, zero, zero, zero, zero, minus_i, zero, zero, i, + zero, + ], + ) +} + +fn controlled_x_matrix() -> Matrix { + Matrix::from_data( + 4, + vec![ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ) +} + +fn controlled_z_matrix() -> Matrix { + Matrix::from_data( + 4, + vec![ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(-1.0, 0.0), + ], + ) +} + +fn swap_matrix() -> Matrix { + Matrix::from_data( + 4, + vec![ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + ], + ) +} diff --git a/crates/pecos-simulators/src/coin_toss.rs b/crates/pecos-simulators/src/coin_toss.rs index 42160377b..3b8442e7a 100644 --- a/crates/pecos-simulators/src/coin_toss.rs +++ b/crates/pecos-simulators/src/coin_toss.rs @@ -220,6 +220,10 @@ impl QuantumSimulator for CoinToss where R: Rng + SeedableRng + Debug, { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { // CoinToss is stateless, so reset is a no-op self diff --git a/crates/pecos-simulators/src/dense_stab.rs b/crates/pecos-simulators/src/dense_stab.rs index 230c3d69c..fc77da9fd 100644 --- a/crates/pecos-simulators/src/dense_stab.rs +++ b/crates/pecos-simulators/src/dense_stab.rs @@ -1030,6 +1030,10 @@ impl DenseStab { } impl QuantumSimulator for DenseStab { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { self.init_state(); self @@ -1341,10 +1345,6 @@ impl StabilizerTableauSimulator for DenseS &self.destab_signs_i, ) } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } impl DenseStab { diff --git a/crates/pecos-simulators/src/dense_stab_variants.rs b/crates/pecos-simulators/src/dense_stab_variants.rs index 6ba6e6068..9daf77d7f 100644 --- a/crates/pecos-simulators/src/dense_stab_variants.rs +++ b/crates/pecos-simulators/src/dense_stab_variants.rs @@ -706,6 +706,10 @@ impl DenseStabColOnly { } impl QuantumSimulator for DenseStabColOnly { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { self.init_state(); self @@ -1236,6 +1240,10 @@ impl DenseStabRowOnly { } impl QuantumSimulator for DenseStabRowOnly { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { self.init_state(); self @@ -1680,6 +1688,10 @@ impl SparseColOnly { } impl QuantumSimulator for SparseColOnly { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { let n = self.num_qubits; for q in 0..n { @@ -2129,6 +2141,10 @@ impl SparseRowOnly { } impl QuantumSimulator for SparseRowOnly { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { let n = self.num_qubits; for g in 0..n { @@ -2293,10 +2309,6 @@ impl StabilizerTableauSimulator for DenseS &self.destab_signs_i, ) } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } impl StabilizerTableauSimulator for DenseStabRowOnly { @@ -2321,10 +2333,6 @@ impl StabilizerTableauSimulator for DenseS &self.destab_signs_i, ) } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } impl StabilizerTableauSimulator for SparseColOnly { @@ -2347,10 +2355,6 @@ impl StabilizerTableauSimulator for SparseColOnly { &self.destab_signs_i, ) } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } /// Build a tableau string from sparse column storage (`SmallVec`<[u16; 8]>). @@ -2447,10 +2451,6 @@ impl StabilizerTableauSimulator for SparseRowOnly { &self.destab_signs_i, ) } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } // ========== ForcedMeasurement implementations ========== diff --git a/crates/pecos-simulators/src/density_matrix.rs b/crates/pecos-simulators/src/density_matrix.rs index 1b0008f4b..dce74e0d2 100644 --- a/crates/pecos-simulators/src/density_matrix.rs +++ b/crates/pecos-simulators/src/density_matrix.rs @@ -867,6 +867,10 @@ impl QuantumSimulator for DensityMatrix where R: Rng + SeedableRng + Debug + Clone, { + fn num_qubits(&self) -> usize { + self.num_physical_qubits + } + /// Reset the quantum state to |0...0⟩⟨0...0| /// /// # Returns diff --git a/crates/pecos-simulators/src/gpu_stab.rs b/crates/pecos-simulators/src/gpu_stab.rs index b992488bc..d3be6fc06 100644 --- a/crates/pecos-simulators/src/gpu_stab.rs +++ b/crates/pecos-simulators/src/gpu_stab.rs @@ -624,6 +624,10 @@ impl GpuStab { // ========== Trait implementations ========== impl QuantumSimulator for GpuStab { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { self.init_tableau(); self @@ -745,10 +749,6 @@ impl StabilizerTableauSimulator for GpuStab { &self.destab_signs_i, ) } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } impl GpuStab { diff --git a/crates/pecos-simulators/src/gpu_stab_opt.rs b/crates/pecos-simulators/src/gpu_stab_opt.rs index 1c89b734f..224ec171b 100644 --- a/crates/pecos-simulators/src/gpu_stab_opt.rs +++ b/crates/pecos-simulators/src/gpu_stab_opt.rs @@ -745,6 +745,10 @@ impl GpuStabOpt { // ========== Trait implementations ========== impl QuantumSimulator for GpuStabOpt { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { self.init_tableau(); self @@ -866,10 +870,6 @@ impl StabilizerTableauSimulator for GpuStabOpt { &self.destab_signs_i, ) } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } impl GpuStabOpt { diff --git a/crates/pecos-simulators/src/gpu_stab_parallel.rs b/crates/pecos-simulators/src/gpu_stab_parallel.rs index 1b7542f35..570579b4b 100644 --- a/crates/pecos-simulators/src/gpu_stab_parallel.rs +++ b/crates/pecos-simulators/src/gpu_stab_parallel.rs @@ -659,6 +659,10 @@ impl GpuStabParallel { // ========== Trait implementations ========== impl QuantumSimulator for GpuStabParallel { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { self.init_tableau(); self @@ -780,10 +784,6 @@ impl StabilizerTableauSimulator for GpuStabParallel { &self.destab_signs_i, ) } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } impl GpuStabParallel { diff --git a/crates/pecos-simulators/src/graph_state.rs b/crates/pecos-simulators/src/graph_state.rs index 85a493ff8..c620879f3 100644 --- a/crates/pecos-simulators/src/graph_state.rs +++ b/crates/pecos-simulators/src/graph_state.rs @@ -473,6 +473,10 @@ impl GraphStateSim { // ============================================================================ impl QuantumSimulator for GraphStateSim { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { // |0>^n = H^n |+>^n = H^n |G_empty> // So all VOPs are H, and the graph has no edges. @@ -652,10 +656,6 @@ impl crate::StabilizerTableauSimulator for GraphSt } result } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } /// Format a `PauliString` as a tableau line matching the `DenseStab` format. diff --git a/crates/pecos-simulators/src/graph_state_repr.rs b/crates/pecos-simulators/src/graph_state_repr.rs index e9297edf5..d48d0fa26 100644 --- a/crates/pecos-simulators/src/graph_state_repr.rs +++ b/crates/pecos-simulators/src/graph_state_repr.rs @@ -1375,7 +1375,7 @@ impl GraphStateRenderer<'_> { let bracketed = format!("{open}{name}{close}"); if color { let ansi = VOP_ANSI[idx]; - write!(out, " {ansi}{bracketed:>, ); -pub use clifford_rz::ch_form::{CHForm, CHFormGeneric}; -pub use clifford_rz::exact_scalar::ExactScalar; -pub use clifford_rz::sparse_binary_matrix::SparseBinaryMatrix; -pub use clifford_rz::{CliffordRz, CliffordRzBuilder, CliffordRzGeneric}; pub use dense_stab::DenseStab; pub use dense_stab_variants::{DenseStabColOnly, DenseStabRowOnly, SparseColOnly, SparseRowOnly}; pub use density_matrix::DensityMatrix; @@ -80,6 +79,10 @@ pub use gpu_stab_opt::GpuStabOpt; pub use gpu_stab_parallel::GpuStabParallel; pub use graph_state::GraphStateSim; pub use graph_state_repr::{GraphState, GraphStateRenderer}; +pub use stab_vec::ch_form::{CHForm, CHFormGeneric}; +pub use stab_vec::exact_scalar::ExactScalar; +pub use stab_vec::sparse_binary_matrix::SparseBinaryMatrix; +pub use stab_vec::{StabVec, StabVecBuilder, StabVecGeneric}; // pub use paulis::Paulis; pub use measurement_sampler::{ MeasurementKind, MeasurementSampler, MeasurementValidationError, SampleResult, @@ -101,7 +104,6 @@ pub use stabilizer::Stabilizer; pub use stabilizer_tableau::StabilizerTableauSimulator; // StateVec uses the sparse SoA implementation optimized for QEC workloads. // The dense implementation is available as DenseStateVec / StateVecSoA. -pub use state_vec::StateVec as StateVecOld; pub use state_vec_aos::StateVecAoS; pub use state_vec_soa::StateVecSoA as DenseStateVec; pub use state_vec_soa::StateVecSoA; diff --git a/crates/pecos-simulators/src/measurement_stress_test_utils.rs b/crates/pecos-simulators/src/measurement_stress_test_utils.rs new file mode 100644 index 000000000..787c09a0d --- /dev/null +++ b/crates/pecos-simulators/src/measurement_stress_test_utils.rs @@ -0,0 +1,302 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Measurement stress tests for any `ArbitraryRotationGateable` simulator. +//! +//! These tests exercise measurement-related edge cases discovered during +//! STN (Stabilizer Tensor Network) development. They use only measurement +//! outcomes (no state vector access), so any simulator can use them. +//! +//! Test categories: +//! - Re-measurement consistency: measure, then re-measure the same qubit +//! - Measure-gate-measure: measure, apply gates, measure again +//! - Clifford rotations after non-Clifford: RX(pi)/RZ(pi) after T gates +//! - Negative-angle rotations: Tdg, negative RZ/RX angles + +#![allow(clippy::missing_panics_doc)] + +use crate::ArbitraryRotationGateable; +use pecos_core::{Angle64, QubitId, qid}; + +// ============================================================================ +// Re-measurement consistency +// ============================================================================ + +/// After measuring a qubit, re-measuring it should give the same outcome. +/// This verifies that measurement collapse is implemented correctly. +pub fn verify_remeasurement_consistency(sim: &mut S) { + let t = Angle64::QUARTER_TURN / 2u64; + + // Case 1: T|+> then measure twice + sim.reset(); + sim.h(&qid(0)); + sim.rz(t, &qid(0)); + let r1 = sim.mz(&qid(0))[0].outcome; + let r2 = sim.mz(&qid(0))[0].outcome; + assert_eq!(r1, r2, "T|+>: re-measurement should give same outcome"); + + // Case 2: Bell+T then measure both, re-measure first + { + sim.reset(); + sim.h(&qid(0)); + sim.cx(&[(QubitId(0), QubitId(1))]); + sim.rz(t, &qid(0)); + let r0 = sim.mz(&qid(0))[0].outcome; + let _r1 = sim.mz(&qid(1))[0].outcome; + let r0_again = sim.mz(&qid(0))[0].outcome; + assert_eq!( + r0, r0_again, + "Bell+T: re-measurement of q0 should be stable" + ); + } +} + +// ============================================================================ +// Measure-gate-measure +// ============================================================================ + +/// Measure a qubit, apply more gates (including non-Clifford), then measure +/// again. Verifies the post-measurement state is usable. +pub fn verify_measure_gate_measure(sim: &mut S) { + let t = Angle64::QUARTER_TURN / 2u64; + + // Measure q0, then apply T+H on q1, then measure q1 + sim.reset(); + sim.h(&qid(0)); + sim.cx(&[(QubitId(0), QubitId(1))]); + sim.rz(t, &qid(0)); + + let _r0 = sim.mz(&qid(0))[0].outcome; + + // After measuring q0, apply gates on q1 + sim.h(&qid(1)); + sim.rz(t, &qid(1)); + let _r1 = sim.mz(&qid(1)); // Should not panic +} + +/// Multiple rounds of measure-gate-measure on a 3-qubit system. +pub fn verify_measure_gate_measure_3qubit(sim: &mut S) { + let t = Angle64::QUARTER_TURN / 2u64; + + sim.reset(); + sim.h(&qid(0)); + sim.cx(&[(QubitId(0), QubitId(1))]); + sim.cx(&[(QubitId(1), QubitId(2))]); + sim.rz(t, &qid(1)); + + // Measure q0 + let _r0 = sim.mz(&qid(0))[0].outcome; + + // Apply more gates after measurement + sim.h(&qid(1)); + sim.rz(t, &qid(1)); + + // Measure q1 and q2 + let _r1 = sim.mz(&qid(1))[0].outcome; + let _r2 = sim.mz(&qid(2))[0].outcome; +} + +// ============================================================================ +// Clifford rotations after non-Clifford gates +// ============================================================================ + +/// RX(pi) = -i*X after non-Clifford gates. The Clifford-angle detection +/// path in RZ must handle the case where the MPS already has non-Clifford +/// content. Tests the X/Y/Z gate destab sign tracking. +pub fn verify_rx_pi_after_nonclifford(sim: &mut S) { + let t = Angle64::QUARTER_TURN / 2u64; + let pi = Angle64::from_radians(std::f64::consts::PI); + + // H, T, RX(pi) on single qubit + sim.reset(); + sim.h(&qid(0)); + sim.rz(t, &qid(0)); + sim.rx(pi, &qid(0)); + // RX(pi)*T|+> should be measurable without panic + let _r = sim.mz(&qid(0)); + + // H, T, then RZ(pi) (= Z up to phase) + sim.reset(); + sim.h(&qid(0)); + sim.rz(t, &qid(0)); + sim.rz(Angle64::HALF_TURN, &qid(0)); + let _r = sim.mz(&qid(0)); + + // Entangled case: Bell + T + RX(pi) + { + sim.reset(); + sim.h(&qid(0)); + sim.cx(&[(QubitId(0), QubitId(1))]); + sim.rz(t, &qid(0)); + sim.rz(t, &qid(1)); + sim.rx(pi, &qid(0)); + + let r0 = sim.mz(&qid(0))[0].outcome; + let r1 = sim.mz(&qid(1))[0].outcome; + // RX(pi)=X flips one qubit of the Bell pair: outcomes are anti-correlated + assert_ne!(r0, r1, "Bell+T+RX(pi): outcomes should be anti-correlated"); + } +} + +/// RZ at all Clifford angles after non-Clifford gates. +pub fn verify_rz_clifford_angles_after_nonclifford(sim: &mut S) { + let t = Angle64::QUARTER_TURN / 2u64; + + let clifford_angles = [ + Angle64::ZERO, + Angle64::QUARTER_TURN, + Angle64::HALF_TURN, + Angle64::THREE_QUARTERS_TURN, + ]; + + for &angle in &clifford_angles { + sim.reset(); + sim.h(&qid(0)); + sim.rz(t, &qid(0)); // Non-Clifford first + sim.rz(angle, &qid(0)); // Clifford angle after + let _r = sim.mz(&qid(0)); // Should not panic + } +} + +// ============================================================================ +// Negative-angle rotations +// ============================================================================ + +/// Tdg = RZ(-pi/4). Verify T * Tdg = I and Tdg alone works. +pub fn verify_tdg_basic(sim: &mut S) { + let t = Angle64::QUARTER_TURN / 2u64; + let tdg = -t; + + // T * Tdg = I on |+> + sim.reset(); + sim.h(&qid(0)); + sim.rz(t, &qid(0)); + sim.rz(tdg, &qid(0)); + // Should be back in |+>, deterministic X measurement + let r = sim.mx(&qid(0)); + assert!( + r[0].is_deterministic, + "T*Tdg|+> should be deterministic in X" + ); + assert!(!r[0].outcome, "T*Tdg|+> should measure 0 in X"); + + // Tdg alone on |+>: p(0) = p(1) = 0.5. Just verify no panic. + sim.reset(); + sim.h(&qid(0)); + sim.rz(tdg, &qid(0)); + let _r = sim.mz(&qid(0)); +} + +/// Negative-angle rotations produce valid states. +pub fn verify_negative_angle_rotations(sim: &mut S) { + let t = Angle64::QUARTER_TURN / 2u64; + let tdg = -t; + + // Tdg on |0>: deterministic (Z is stabilizer), should always measure 0 + sim.reset(); + sim.rz(tdg, &qid(0)); + let r = sim.mz(&qid(0)); + assert!(!r[0].outcome, "Tdg|0> should measure 0"); + + // Tdg on |+> produces valid state (no panic, non-deterministic in Z) + sim.reset(); + sim.h(&qid(0)); + sim.rz(tdg, &qid(0)); + let _r = sim.mz(&qid(0)); + + // Negative-angle RX on |0> (no panic) + sim.reset(); + sim.rx(-t, &qid(0)); + let _r = sim.mz(&qid(0)); +} + +// ============================================================================ +// Measurement probability distribution check +// ============================================================================ + +/// Statistical check: RX(pi/3)|0> should give p(0) = cos^2(pi/6) = 3/4. +/// Runs many trials and checks the distribution. +pub fn verify_rx_measurement_probabilities( + sim: &mut S, + num_trials: usize, +) { + let theta = Angle64::from_radians(std::f64::consts::FRAC_PI_3); + let expected_p0 = 0.75; + let mut count_0 = 0u32; + + for _ in 0..num_trials { + sim.reset(); + sim.rx(theta, &qid(0)); + if !sim.mz(&qid(0))[0].outcome { + count_0 += 1; + } + } + + let p0 = f64::from(count_0) + / f64::from(u32::try_from(num_trials).expect("num_trials must fit in u32")); + assert!( + (p0 - expected_p0).abs() < 0.1, + "RX(pi/3)|0> p(0) = {p0:.3}, expected {expected_p0:.3}" + ); +} + +// ============================================================================ +// Main runner +// ============================================================================ + +/// Run the full measurement stress test suite. +pub fn run_measurement_stress_tests(sim: &mut S) { + verify_remeasurement_consistency(sim); + verify_measure_gate_measure(sim); + verify_measure_gate_measure_3qubit(sim); + verify_rx_pi_after_nonclifford(sim); + verify_rz_clifford_angles_after_nonclifford(sim); + verify_tdg_basic(sim); + verify_negative_angle_rotations(sim); + verify_rx_measurement_probabilities(sim, 200); +} + +/// Generate a test that runs the measurement stress suite on a simulator type. +/// +/// Usage: +/// ```ignore +/// use pecos_simulators::measurement_stress_test_suite; +/// measurement_stress_test_suite!(StabVec, 4); +/// ``` +#[macro_export] +macro_rules! measurement_stress_test_suite { + ($sim_type:ty) => { + $crate::measurement_stress_test_suite!($sim_type, 4); + }; + ($sim_type:ty, $num_qubits:expr) => { + paste::paste! { + #[test] + fn []() { + use $crate::measurement_stress_test_utils::run_measurement_stress_tests; + let mut sim = <$sim_type>::builder($num_qubits).seed(42).build(); + run_measurement_stress_tests(&mut sim); + } + } + }; + ($sim_type:ty, $num_qubits:expr, $constructor:expr) => { + paste::paste! { + #[test] + fn []() { + use $crate::measurement_stress_test_utils::run_measurement_stress_tests; + #[allow(unused_variables)] + let num_qubits: usize = $num_qubits; + let mut sim = $constructor; + run_measurement_stress_tests(&mut sim); + } + } + }; +} diff --git a/crates/pecos-simulators/src/pauli_prop.rs b/crates/pecos-simulators/src/pauli_prop.rs index b89de6a8b..b370d85d1 100644 --- a/crates/pecos-simulators/src/pauli_prop.rs +++ b/crates/pecos-simulators/src/pauli_prop.rs @@ -111,6 +111,10 @@ impl PauliProp { } impl QuantumSimulator for PauliProp { + fn num_qubits(&self) -> usize { + self.num_qubits.unwrap_or(0) + } + /// Resets the state by clearing all Pauli all tracked X and Z operators. /// /// # Returns @@ -368,6 +372,15 @@ impl PauliProp { count } + /// Remove all Pauli operators from a specific qubit. + /// + /// Models reset (PZ) which absorbs any propagating error on that qubit. + pub fn clear_qubit(&mut self, qubit: usize) { + use pecos_core::sets::set::Set; + self.xs.remove(&qubit); + self.zs.remove(&qubit); + } + /// Checks if this is the identity operator (no Pauli operators on any qubit). /// /// # Returns @@ -533,6 +546,23 @@ impl PauliProp { pub fn to_dense_string(&self) -> String { format!("{}{}", self.sign_string(), self.dense_string()) } + + fn set_x_component(&mut self, q: usize, value: bool) { + if self.contains_x(q) != value { + self.track_x(&[q]); + } + } + + fn set_z_component(&mut self, q: usize, value: bool) { + if self.contains_z(q) != value { + self.track_z(&[q]); + } + } + + fn set_components(&mut self, q: usize, x: bool, z: bool) { + self.set_x_component(q, x); + self.set_z_component(q, z); + } } impl fmt::Display for PauliProp { @@ -569,6 +599,21 @@ impl CliffordGateable for PauliProp { self } + /// Applies the adjoint square root of Z gate. + /// + /// Ignoring global phase, SZ and SZdg have the same binary Pauli action: + /// X <-> Y, Z -> Z. + #[inline] + fn szdg(&mut self, qubits: &[QubitId]) -> &mut Self { + for &q in qubits { + let qu = q.index(); + if self.contains_x(qu) { + self.track_z(&[qu]); + } + } + self + } + /// Applies the Hadamard (H) gate to the specified qubits. /// /// The H gate transforms Pauli operators as follows: @@ -607,6 +652,62 @@ impl CliffordGateable for PauliProp { self } + /// Applies the square root of X gate. + /// + /// Binary Pauli action: X -> X, Z <-> Y. + #[inline] + fn sx(&mut self, qubits: &[QubitId]) -> &mut Self { + for &q in qubits { + let qu = q.index(); + if self.contains_z(qu) { + self.track_x(&[qu]); + } + } + self + } + + /// Applies the adjoint square root of X gate. + /// + /// Ignoring global phase, SX and SXdg have the same binary Pauli action. + #[inline] + fn sxdg(&mut self, qubits: &[QubitId]) -> &mut Self { + for &q in qubits { + let qu = q.index(); + if self.contains_z(qu) { + self.track_x(&[qu]); + } + } + self + } + + /// Applies the square root of Y gate. + /// + /// Binary Pauli action: X <-> Z, Y -> Y. + #[inline] + fn sy(&mut self, qubits: &[QubitId]) -> &mut Self { + for &q in qubits { + let qu = q.index(); + let x = self.contains_x(qu); + let z = self.contains_z(qu); + self.set_components(qu, z, x); + } + self + } + + /// Applies the adjoint square root of Y gate. + /// + /// Ignoring global phase, SY and SYdg have the same binary Pauli action. + #[inline] + fn sydg(&mut self, qubits: &[QubitId]) -> &mut Self { + for &q in qubits { + let qu = q.index(); + let x = self.contains_x(qu); + let z = self.contains_z(qu); + self.set_components(qu, z, x); + } + self + } + /// Applies the controlled-X (CX) gate between pairs of qubits /// /// The CX gate transforms Pauli operators as follows: @@ -641,6 +742,160 @@ impl CliffordGateable for PauliProp { self } + /// Applies the controlled-Y gate. + #[inline] + fn cy(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + self.set_components(q1, x1, z1 ^ x2 ^ z2); + self.set_components(q2, x2 ^ x1, z2 ^ x1); + } + self + } + + /// Applies the controlled-Z gate. + #[inline] + fn cz(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + self.set_components(q1, x1, z1 ^ x2); + self.set_components(q2, x2, z2 ^ x1); + } + self + } + + /// Applies the square root of XX gate. + #[inline] + fn sxx(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + let affected = z1 ^ z2; + self.set_components(q1, x1 ^ affected, z1); + self.set_components(q2, x2 ^ affected, z2); + } + self + } + + /// Applies the adjoint square root of XX gate. + /// + /// Ignoring global phase, SXX and SXXdg have the same binary Pauli action. + #[inline] + fn sxxdg(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + let affected = z1 ^ z2; + self.set_components(q1, x1 ^ affected, z1); + self.set_components(q2, x2 ^ affected, z2); + } + self + } + + /// Applies the square root of YY gate. + #[inline] + fn syy(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + self.set_components(q1, x2 ^ z1 ^ z2, x1 ^ x2 ^ z2); + self.set_components(q2, x1 ^ z1 ^ z2, x1 ^ x2 ^ z1); + } + self + } + + /// Applies the adjoint square root of YY gate. + /// + /// Ignoring global phase, SYY and SYYdg have the same binary Pauli action. + #[inline] + fn syydg(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + self.set_components(q1, x2 ^ z1 ^ z2, x1 ^ x2 ^ z2); + self.set_components(q2, x1 ^ z1 ^ z2, x1 ^ x2 ^ z1); + } + self + } + + /// Applies the square root of ZZ gate. + #[inline] + fn szz(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + let affected = x1 ^ x2; + self.set_components(q1, x1, z1 ^ affected); + self.set_components(q2, x2, z2 ^ affected); + } + self + } + + /// Applies the adjoint square root of ZZ gate. + /// + /// Ignoring global phase, SZZ and SZZdg have the same binary Pauli action. + #[inline] + fn szzdg(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + let affected = x1 ^ x2; + self.set_components(q1, x1, z1 ^ affected); + self.set_components(q2, x2, z2 ^ affected); + } + self + } + + /// Applies the SWAP gate. + #[inline] + fn swap(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + self.set_components(q1, x2, z2); + self.set_components(q2, x1, z1); + } + self + } + /// Performs a Z-basis measurement on the specified qubits. /// /// This simulates the effect of Pauli operators on measurement due to propagation. @@ -676,8 +931,106 @@ impl CliffordGateable for PauliProp { #[cfg(test)] mod tests { use super::*; + use crate::clifford_matrix_oracle::{CliffordMatrixGate, all_pauli_strings, conjugate_pauli}; use std::collections::BTreeMap; + fn prop_from_dense(input: &str) -> PauliProp { + let mut prop = PauliProp::with_sign_tracking(input.len()); + for (q, p) in input.chars().enumerate() { + match p { + 'I' => {} + 'X' => prop.track_x(&[q]), + 'Y' => prop.track_y(&[q]), + 'Z' => prop.track_z(&[q]), + _ => panic!("invalid Pauli label {p}"), + } + } + prop + } + + fn assert_gate_table(name: &str, table: &[(&str, &str)], mut apply: F) + where + F: FnMut(&mut PauliProp), + { + for &(input, expected) in table { + let mut prop = prop_from_dense(input); + apply(&mut prop); + assert_eq!(prop.dense_string(), expected, "{name}: {input}"); + } + } + + fn assert_gate_matches_matrix_oracle( + name: &str, + gate: CliffordMatrixGate, + num_qubits: usize, + mut apply: F, + ) where + F: FnMut(&mut PauliProp), + { + for input in all_pauli_strings(num_qubits) { + let expected = conjugate_pauli(gate, &input); + let mut prop = prop_from_dense(&input); + apply(&mut prop); + assert_eq!( + prop.dense_string(), + expected.pauli, + "{name}: {input}, oracle sign {}", + expected.sign + ); + } + } + + fn reverse_two_qubit_pauli(pauli: &str) -> String { + let labels: Vec = pauli.chars().collect(); + assert_eq!(labels.len(), 2); + [labels[1], labels[0]].into_iter().collect() + } + + fn assert_reversed_pair_matches_matrix_oracle( + name: &str, + gate: CliffordMatrixGate, + mut apply: F, + ) where + F: FnMut(&mut PauliProp, &[(QubitId, QubitId)]), + { + let reversed_pair = [(QubitId(1), QubitId(0))]; + for input in all_pauli_strings(2) { + let oracle_input = reverse_two_qubit_pauli(&input); + let mut expected = conjugate_pauli(gate, &oracle_input); + expected.pauli = reverse_two_qubit_pauli(&expected.pauli); + + let mut prop = prop_from_dense(&input); + apply(&mut prop, &reversed_pair); + assert_eq!( + prop.dense_string(), + expected.pauli, + "{name} reversed pair: {input}, oracle sign {}", + expected.sign + ); + } + } + + fn assert_two_pair_batch_matches_sequential(name: &str, mut apply: F) + where + F: FnMut(&mut PauliProp, &[(QubitId, QubitId)]), + { + let pairs = [(QubitId(0), QubitId(1)), (QubitId(2), QubitId(3))]; + for input in all_pauli_strings(4) { + let mut batched = prop_from_dense(&input); + apply(&mut batched, &pairs); + + let mut sequential = prop_from_dense(&input); + apply(&mut sequential, &pairs[0..1]); + apply(&mut sequential, &pairs[1..2]); + + assert_eq!( + batched.dense_string(), + sequential.dense_string(), + "{name} batched: {input}" + ); + } + } + #[test] fn test_sign_tracking() { let mut sim = PauliProp::with_sign_tracking(4); @@ -781,4 +1134,265 @@ mod tests { // Phase should be -i (X·Z = -iY) assert_eq!(sim.sign_string(), "-i"); } + + #[test] + fn test_direct_clifford_gate_binary_truth_tables() { + let q0 = QubitId(0); + let q1 = QubitId(1); + let pair = [(q0, q1)]; + + assert_gate_table( + "SZdg", + &[("I", "I"), ("X", "Y"), ("Y", "X"), ("Z", "Z")], + |prop| { + prop.szdg(&[q0]); + }, + ); + assert_gate_table( + "SX", + &[("I", "I"), ("X", "X"), ("Y", "Z"), ("Z", "Y")], + |prop| { + prop.sx(&[q0]); + }, + ); + assert_gate_table( + "SXdg", + &[("I", "I"), ("X", "X"), ("Y", "Z"), ("Z", "Y")], + |prop| { + prop.sxdg(&[q0]); + }, + ); + assert_gate_table( + "SY", + &[("I", "I"), ("X", "Z"), ("Y", "Y"), ("Z", "X")], + |prop| { + prop.sy(&[q0]); + }, + ); + assert_gate_table( + "SYdg", + &[("I", "I"), ("X", "Z"), ("Y", "Y"), ("Z", "X")], + |prop| { + prop.sydg(&[q0]); + }, + ); + assert_gate_table( + "CY", + &[("XI", "XY"), ("IX", "ZX"), ("ZI", "ZI"), ("IZ", "ZZ")], + |prop| { + prop.cy(&pair); + }, + ); + assert_gate_table( + "CZ", + &[("XI", "XZ"), ("IX", "ZX"), ("ZI", "ZI"), ("IZ", "IZ")], + |prop| { + prop.cz(&pair); + }, + ); + assert_gate_table( + "SXX", + &[("XI", "XI"), ("IX", "IX"), ("ZI", "YX"), ("IZ", "XY")], + |prop| { + prop.sxx(&pair); + }, + ); + assert_gate_table( + "SXXdg", + &[("XI", "XI"), ("IX", "IX"), ("ZI", "YX"), ("IZ", "XY")], + |prop| { + prop.sxxdg(&pair); + }, + ); + assert_gate_table( + "SYY", + &[("XI", "ZY"), ("IX", "YZ"), ("ZI", "XY"), ("IZ", "YX")], + |prop| { + prop.syy(&pair); + }, + ); + assert_gate_table( + "SYYdg", + &[("XI", "ZY"), ("IX", "YZ"), ("ZI", "XY"), ("IZ", "YX")], + |prop| { + prop.syydg(&pair); + }, + ); + assert_gate_table( + "SZZ", + &[("XI", "YZ"), ("IX", "ZY"), ("ZI", "ZI"), ("IZ", "IZ")], + |prop| { + prop.szz(&pair); + }, + ); + assert_gate_table( + "SZZdg", + &[("XI", "YZ"), ("IX", "ZY"), ("ZI", "ZI"), ("IZ", "IZ")], + |prop| { + prop.szzdg(&pair); + }, + ); + assert_gate_table( + "SWAP", + &[("XI", "IX"), ("IX", "XI"), ("ZI", "IZ"), ("IZ", "ZI")], + |prop| { + prop.swap(&pair); + }, + ); + } + + #[test] + fn test_direct_clifford_gates_match_matrix_oracle_for_all_paulis() { + let q0 = QubitId(0); + let q1 = QubitId(1); + let pair = [(q0, q1)]; + + assert_gate_matches_matrix_oracle("CX", CliffordMatrixGate::CX, 2, |prop| { + prop.cx(&pair); + }); + assert_gate_matches_matrix_oracle("SZdg", CliffordMatrixGate::SZdg, 1, |prop| { + prop.szdg(&[q0]); + }); + assert_gate_matches_matrix_oracle("F", CliffordMatrixGate::F, 1, |prop| { + prop.f(&[q0]); + }); + assert_gate_matches_matrix_oracle("Fdg", CliffordMatrixGate::Fdg, 1, |prop| { + prop.fdg(&[q0]); + }); + assert_gate_matches_matrix_oracle("SX", CliffordMatrixGate::SX, 1, |prop| { + prop.sx(&[q0]); + }); + assert_gate_matches_matrix_oracle("SXdg", CliffordMatrixGate::SXdg, 1, |prop| { + prop.sxdg(&[q0]); + }); + assert_gate_matches_matrix_oracle("SY", CliffordMatrixGate::SY, 1, |prop| { + prop.sy(&[q0]); + }); + assert_gate_matches_matrix_oracle("SYdg", CliffordMatrixGate::SYdg, 1, |prop| { + prop.sydg(&[q0]); + }); + assert_gate_matches_matrix_oracle("CY", CliffordMatrixGate::CY, 2, |prop| { + prop.cy(&pair); + }); + assert_gate_matches_matrix_oracle("CZ", CliffordMatrixGate::CZ, 2, |prop| { + prop.cz(&pair); + }); + assert_gate_matches_matrix_oracle("SXX", CliffordMatrixGate::SXX, 2, |prop| { + prop.sxx(&pair); + }); + assert_gate_matches_matrix_oracle("SXXdg", CliffordMatrixGate::SXXdg, 2, |prop| { + prop.sxxdg(&pair); + }); + assert_gate_matches_matrix_oracle("SYY", CliffordMatrixGate::SYY, 2, |prop| { + prop.syy(&pair); + }); + assert_gate_matches_matrix_oracle("SYYdg", CliffordMatrixGate::SYYdg, 2, |prop| { + prop.syydg(&pair); + }); + assert_gate_matches_matrix_oracle("SZZ", CliffordMatrixGate::SZZ, 2, |prop| { + prop.szz(&pair); + }); + assert_gate_matches_matrix_oracle("SZZdg", CliffordMatrixGate::SZZdg, 2, |prop| { + prop.szzdg(&pair); + }); + assert_gate_matches_matrix_oracle("SWAP", CliffordMatrixGate::SWAP, 2, |prop| { + prop.swap(&pair); + }); + } + + #[test] + fn test_two_qubit_gates_reversed_pair_matches_matrix_oracle() { + assert_reversed_pair_matches_matrix_oracle("CX", CliffordMatrixGate::CX, |prop, pairs| { + prop.cx(pairs); + }); + assert_reversed_pair_matches_matrix_oracle("CY", CliffordMatrixGate::CY, |prop, pairs| { + prop.cy(pairs); + }); + assert_reversed_pair_matches_matrix_oracle("CZ", CliffordMatrixGate::CZ, |prop, pairs| { + prop.cz(pairs); + }); + assert_reversed_pair_matches_matrix_oracle( + "SXX", + CliffordMatrixGate::SXX, + |prop, pairs| { + prop.sxx(pairs); + }, + ); + assert_reversed_pair_matches_matrix_oracle( + "SXXdg", + CliffordMatrixGate::SXXdg, + |prop, pairs| { + prop.sxxdg(pairs); + }, + ); + assert_reversed_pair_matches_matrix_oracle( + "SYY", + CliffordMatrixGate::SYY, + |prop, pairs| { + prop.syy(pairs); + }, + ); + assert_reversed_pair_matches_matrix_oracle( + "SYYdg", + CliffordMatrixGate::SYYdg, + |prop, pairs| { + prop.syydg(pairs); + }, + ); + assert_reversed_pair_matches_matrix_oracle( + "SZZ", + CliffordMatrixGate::SZZ, + |prop, pairs| { + prop.szz(pairs); + }, + ); + assert_reversed_pair_matches_matrix_oracle( + "SZZdg", + CliffordMatrixGate::SZZdg, + |prop, pairs| { + prop.szzdg(pairs); + }, + ); + assert_reversed_pair_matches_matrix_oracle( + "SWAP", + CliffordMatrixGate::SWAP, + |prop, pairs| { + prop.swap(pairs); + }, + ); + } + + #[test] + fn test_two_qubit_gate_batches_match_sequential_pairs() { + assert_two_pair_batch_matches_sequential("CX", |prop, pairs| { + prop.cx(pairs); + }); + assert_two_pair_batch_matches_sequential("CY", |prop, pairs| { + prop.cy(pairs); + }); + assert_two_pair_batch_matches_sequential("CZ", |prop, pairs| { + prop.cz(pairs); + }); + assert_two_pair_batch_matches_sequential("SXX", |prop, pairs| { + prop.sxx(pairs); + }); + assert_two_pair_batch_matches_sequential("SXXdg", |prop, pairs| { + prop.sxxdg(pairs); + }); + assert_two_pair_batch_matches_sequential("SYY", |prop, pairs| { + prop.syy(pairs); + }); + assert_two_pair_batch_matches_sequential("SYYdg", |prop, pairs| { + prop.syydg(pairs); + }); + assert_two_pair_batch_matches_sequential("SZZ", |prop, pairs| { + prop.szz(pairs); + }); + assert_two_pair_batch_matches_sequential("SZZdg", |prop, pairs| { + prop.szzdg(pairs); + }); + assert_two_pair_batch_matches_sequential("SWAP", |prop, pairs| { + prop.swap(pairs); + }); + } } diff --git a/crates/pecos-simulators/src/quantum_simulator.rs b/crates/pecos-simulators/src/quantum_simulator.rs index 02973e3d5..4b747d0bb 100644 --- a/crates/pecos-simulators/src/quantum_simulator.rs +++ b/crates/pecos-simulators/src/quantum_simulator.rs @@ -37,4 +37,7 @@ pub trait QuantumSimulator { /// .z(&qid(1)); // Can continue chaining methods /// ``` fn reset(&mut self) -> &mut Self; + + /// Returns the number of qubits in the simulator. + fn num_qubits(&self) -> usize; } diff --git a/crates/pecos-simulators/src/sparse_stab.rs b/crates/pecos-simulators/src/sparse_stab.rs index 19c62894b..0432793aa 100644 --- a/crates/pecos-simulators/src/sparse_stab.rs +++ b/crates/pecos-simulators/src/sparse_stab.rs @@ -104,6 +104,10 @@ pub struct SparseStabGeneric, pub(crate) destabs: GensGeneric, pub(crate) rng: R, + /// When true, maintain destabilizer signs through Clifford gates. + /// Off by default (not needed for standard stabilizer simulation). + /// Required for STN-style decomposition that uses destabilizer phases. + track_destab_signs: bool, } /// Default sparse stabilizer simulator using `BitSet` for O(1) toggle operations. @@ -269,11 +273,27 @@ where stabs: GensGeneric::::new(num_qubits), destabs: GensGeneric::::new(num_qubits), rng, + track_destab_signs: false, }; stab.reset(); stab } + /// Enable tracking of destabilizer signs through Clifford gates. + /// Required for STN-style decomposition that uses destabilizer phases. + #[inline] + #[must_use] + pub fn with_destab_sign_tracking(mut self) -> Self { + self.track_destab_signs = true; + self + } + + /// Whether destabilizer sign tracking is enabled. + #[inline] + pub fn tracks_destab_signs(&self) -> bool { + self.track_destab_signs + } + #[inline] pub fn reset(&mut self) -> &mut Self { self.stabs.init_all_z(); @@ -572,6 +592,9 @@ where if result.outcome { // Inline X gate: X -> X, Z -> -Z self.stabs.signs_minus.xor_assign(&self.stabs.col_z[q]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[q]); + } } self } @@ -593,6 +616,10 @@ where S: IndexSet, R: SeedableRng + Rng + Debug, { + fn num_qubits(&self) -> usize { + self.num_qubits + } + #[inline] fn reset(&mut self) -> &mut Self { Self::reset(self) @@ -613,6 +640,9 @@ where for &q in qubits { let qu = q.index(); self.stabs.signs_minus.xor_assign(&self.stabs.col_z[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + } } self } @@ -625,6 +655,12 @@ where // Fused: XOR elements in (col_x[qu] ⊕ col_z[qu]) into signs_minus self.stabs.col_x[qu] .xor_symmetric_difference_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.col_x[qu].xor_symmetric_difference_into( + &self.destabs.col_z[qu], + &mut self.destabs.signs_minus, + ); + } } self } @@ -633,9 +669,11 @@ where #[inline] fn z(&mut self, qubits: &[QubitId]) -> &mut Self { for &q in qubits { - self.stabs - .signs_minus - .xor_assign(&self.stabs.col_x[q.index()]); + let qu = q.index(); + self.stabs.signs_minus.xor_assign(&self.stabs.col_x[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + } } self } @@ -661,6 +699,12 @@ where .signs_i .xor_intersection_into(&self.stabs.col_x[qu], &mut self.stabs.signs_minus); self.stabs.signs_i.xor_assign(&self.stabs.col_x[qu]); + if self.track_destab_signs { + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_x[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_x[qu]); + } for g in [&mut self.stabs, &mut self.destabs] { g.col_z[qu].xor_assign(&g.col_x[qu]); @@ -682,6 +726,10 @@ where // Fused: XOR elements in (col_x[qu] ∩ col_z[qu]) into signs_minus self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } for g in [&mut self.stabs, &mut self.destabs] { // Elements in col_x but not in col_z: X -> Z @@ -721,6 +769,13 @@ where .signs_i .xor_intersection_into(&self.stabs.col_x[qu], &mut self.stabs.signs_minus); self.stabs.signs_i.xor_assign(&self.stabs.col_x[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_x[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_x[qu]); + } // Data: col_z ^= col_x (same as SZ) for g in [&mut self.stabs, &mut self.destabs] { @@ -745,6 +800,13 @@ where .signs_i .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); self.stabs.signs_i.xor_assign(&self.stabs.col_z[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_z[qu]); + } // Data: col_x ^= col_z for g in [&mut self.stabs, &mut self.destabs] { @@ -768,6 +830,12 @@ where .signs_i .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); self.stabs.signs_i.xor_assign(&self.stabs.col_z[qu]); + if self.track_destab_signs { + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_z[qu]); + } // Data: col_x ^= col_z for g in [&mut self.stabs, &mut self.destabs] { @@ -791,6 +859,11 @@ where self.stabs.signs_minus.xor_assign(&self.stabs.col_x[qu]); self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } // Data: swap col_x <-> col_z (same as H) for g in [&mut self.stabs, &mut self.destabs] { @@ -823,6 +896,11 @@ where self.stabs.signs_minus.xor_assign(&self.stabs.col_z[qu]); self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } // Data: swap col_x <-> col_z (same as H) for g in [&mut self.stabs, &mut self.destabs] { @@ -857,6 +935,12 @@ where self.stabs.signs_minus.xor_assign(&self.stabs.col_z[qu]); self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } // Data: swap col_x <-> col_z (same as H) for g in [&mut self.stabs, &mut self.destabs] { @@ -890,6 +974,13 @@ where .signs_i .xor_intersection_into(&self.stabs.col_x[qu], &mut self.stabs.signs_minus); self.stabs.signs_i.xor_assign(&self.stabs.col_x[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_x[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_x[qu]); + } // Data: col_z ^= col_x (same as SZ) for g in [&mut self.stabs, &mut self.destabs] { @@ -915,6 +1006,14 @@ where .signs_i .xor_intersection_into(&self.stabs.col_x[qu], &mut self.stabs.signs_minus); self.stabs.signs_i.xor_assign(&self.stabs.col_x[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_x[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_x[qu]); + } // Data: col_z ^= col_x (same as SZ) for g in [&mut self.stabs, &mut self.destabs] { @@ -939,6 +1038,13 @@ where .signs_i .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); self.stabs.signs_i.xor_assign(&self.stabs.col_z[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_z[qu]); + } // Data: col_x ^= col_z (same as SX) for g in [&mut self.stabs, &mut self.destabs] { @@ -964,6 +1070,14 @@ where .signs_i .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); self.stabs.signs_i.xor_assign(&self.stabs.col_z[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_z[qu]); + } // Data: col_x ^= col_z (same as SX) for g in [&mut self.stabs, &mut self.destabs] { @@ -989,6 +1103,14 @@ where self.stabs.signs_i.xor_assign(&self.stabs.col_x[qu]); self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_x[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_x[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } // Data: col_z ^= col_x, then swap col_x <-> col_z // Row updates: (1,0)->(1,1): insert row_z; (0,1)->(1,0): move row_z->row_x; (1,1)->(0,1): remove row_x @@ -1029,6 +1151,14 @@ where self.stabs.signs_i.xor_assign(&self.stabs.col_z[qu]); self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_z[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } // Data: col_x ^= col_z, then swap col_x <-> col_z // Row updates: (1,0)->(0,1): move row_x->row_z; (0,1)->(1,1): insert row_x; (1,1)->(1,0): remove row_z @@ -1070,6 +1200,15 @@ where .signs_i .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); self.stabs.signs_i.xor_assign(&self.stabs.col_z[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_z[qu]); + } // Data: col_x ^= col_z, then swap (same as Fdg) for g in [&mut self.stabs, &mut self.destabs] { @@ -1108,6 +1247,16 @@ where .signs_i .xor_intersection_into(&self.stabs.col_x[qu], &mut self.stabs.signs_minus); self.stabs.signs_i.xor_assign(&self.stabs.col_x[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_x[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_x[qu]); + } // Data: col_z ^= col_x, then swap (same as F) for g in [&mut self.stabs, &mut self.destabs] { @@ -1145,6 +1294,15 @@ where .signs_i .xor_intersection_into(&self.stabs.col_x[qu], &mut self.stabs.signs_minus); self.stabs.signs_i.xor_assign(&self.stabs.col_x[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_x[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_x[qu]); + } // Data: col_z ^= col_x, then swap (same as F) for g in [&mut self.stabs, &mut self.destabs] { @@ -1183,6 +1341,16 @@ where .signs_i .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); self.stabs.signs_i.xor_assign(&self.stabs.col_z[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_z[qu]); + } // Data: col_x ^= col_z, then swap (same as Fdg) for g in [&mut self.stabs, &mut self.destabs] { @@ -1220,6 +1388,15 @@ where self.stabs.signs_i.xor_assign(&self.stabs.col_z[qu]); self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_z[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } // Data: col_x ^= col_z, then swap (same as Fdg) for g in [&mut self.stabs, &mut self.destabs] { @@ -1257,6 +1434,15 @@ where self.stabs.signs_i.xor_assign(&self.stabs.col_x[qu]); self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + self.destabs + .signs_i + .xor_intersection_into(&self.destabs.col_x[qu], &mut self.destabs.signs_minus); + self.destabs.signs_i.xor_assign(&self.destabs.col_x[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } // Data: col_z ^= col_x, then swap (same as F) for g in [&mut self.stabs, &mut self.destabs] { @@ -1371,6 +1557,30 @@ where } } } + if self.track_destab_signs { + for g in self.destabs.col_z[q1].iter() { + if !self.destabs.col_z[q2].contains(g) { + self.destabs.signs_minus.toggle(g); + if self.destabs.signs_i.contains(g) { + self.destabs.signs_minus.toggle(g); + self.destabs.signs_i.remove(g); + } else { + self.destabs.signs_i.insert(g); + } + } + } + for g in self.destabs.col_z[q2].iter() { + if !self.destabs.col_z[q1].contains(g) { + self.destabs.signs_minus.toggle(g); + if self.destabs.signs_i.contains(g) { + self.destabs.signs_minus.toggle(g); + self.destabs.signs_i.remove(g); + } else { + self.destabs.signs_i.insert(g); + } + } + } + } // Pauli update (both stabs and destabs): toggle X on q1,q2 for odd-Z generators. for tab in [&mut self.stabs, &mut self.destabs] { @@ -1462,6 +1672,28 @@ where } } } + if self.track_destab_signs { + for g in self.destabs.col_x[q1].iter() { + if !self.destabs.col_x[q2].contains(g) { + if self.destabs.signs_i.contains(g) { + self.destabs.signs_minus.toggle(g); + self.destabs.signs_i.remove(g); + } else { + self.destabs.signs_i.insert(g); + } + } + } + for g in self.destabs.col_x[q2].iter() { + if !self.destabs.col_x[q1].contains(g) { + if self.destabs.signs_i.contains(g) { + self.destabs.signs_minus.toggle(g); + self.destabs.signs_i.remove(g); + } else { + self.destabs.signs_i.insert(g); + } + } + } + } // Pauli update (both stabs and destabs): toggle Z on q1,q2 for odd-X generators. for tab in [&mut self.stabs, &mut self.destabs] { @@ -1605,6 +1837,71 @@ where apply_syy_sign!(g, false, false, false, true); } } + if self.track_destab_signs { + let signs_minus = &mut self.destabs.signs_minus; + let signs_i = &mut self.destabs.signs_i; + let col_x = &self.destabs.col_x; + let col_z = &self.destabs.col_z; + + macro_rules! mul_i { + (plus, $g:expr, $signs_i:expr, $signs_minus:expr) => { + if $signs_i.contains($g) { + $signs_minus.toggle($g); + $signs_i.remove($g); + } else { + $signs_i.insert($g); + } + }; + (minus, $g:expr, $signs_i:expr, $signs_minus:expr) => { + $signs_minus.toggle($g); + mul_i!(plus, $g, $signs_i, $signs_minus); + }; + } + + macro_rules! apply_syy_sign { + ($g:expr, $x1:expr, $z1:expr, $x2:expr, $z2:expr) => { + if ($x1 != $z1) != ($x2 != $z2) { + if $z1 == $z2 { + mul_i!(minus, $g, signs_i, signs_minus); + } else { + mul_i!(plus, $g, signs_i, signs_minus); + } + } + }; + } + + for g in col_x[q1].iter() { + let x1 = true; + let z1 = col_z[q1].contains(g); + let x2 = col_x[q2].contains(g); + let z2 = col_z[q2].contains(g); + apply_syy_sign!(g, x1, z1, x2, z2); + } + for g in col_z[q1].iter() { + if col_x[q1].contains(g) { + continue; + } + let x1 = false; + let z1 = true; + let x2 = col_x[q2].contains(g); + let z2 = col_z[q2].contains(g); + apply_syy_sign!(g, x1, z1, x2, z2); + } + for g in col_x[q2].iter() { + if col_x[q1].contains(g) || col_z[q1].contains(g) { + continue; + } + let x2 = true; + let z2 = col_z[q2].contains(g); + apply_syy_sign!(g, false, false, x2, z2); + } + for g in col_z[q2].iter() { + if col_x[q1].contains(g) || col_z[q1].contains(g) || col_x[q2].contains(g) { + continue; + } + apply_syy_sign!(g, false, false, false, true); + } + } // Pauli update (both stabs and destabs): toggle both X and Z on q1,q2 // for generators where (x1^z1) XOR (x2^z2) = 1. @@ -1767,10 +2064,6 @@ where fn destab_tableau(&self) -> String { Self::tableau_string(self.num_qubits, &self.destabs) } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } // ============================================================================ @@ -2169,6 +2462,7 @@ where stabs, destabs, rng: self.rng, + track_destab_signs: false, } } } @@ -2177,6 +2471,10 @@ impl QuantumSimulator for SparseStabHybrid where R: SeedableRng + Rng + Debug, { + fn num_qubits(&self) -> usize { + self.num_qubits + } + #[inline] fn reset(&mut self) -> &mut Self { Self::reset(self) @@ -3336,10 +3634,6 @@ where fn destab_tableau(&self) -> String { Self::tableau_string(self.num_qubits, &self.destabs) } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } // ============================================================================ diff --git a/crates/pecos-simulators/src/sparse_stab_y.rs b/crates/pecos-simulators/src/sparse_stab_y.rs index 333d791ae..52d4f3124 100644 --- a/crates/pecos-simulators/src/sparse_stab_y.rs +++ b/crates/pecos-simulators/src/sparse_stab_y.rs @@ -43,6 +43,10 @@ pub struct SparseStabYGeneric, pub(crate) destabs: GensGeneric, pub(crate) rng: R, + /// When true, maintain destabilizer signs through Clifford gates. + /// Off by default (not needed for standard stabilizer simulation). + /// Required for STN-style decomposition that uses destabilizer phases. + track_destab_signs: bool, } /// Default Y-convention sparse stabilizer simulator using `BitSet`. @@ -123,11 +127,27 @@ where stabs: GensGeneric::::new(num_qubits), destabs: GensGeneric::::new(num_qubits), rng, + track_destab_signs: false, }; stab.reset(); stab } + /// Enable tracking of destabilizer signs through Clifford gates. + /// Required for STN-style decomposition that uses destabilizer phases. + #[inline] + #[must_use] + pub fn with_destab_sign_tracking(mut self) -> Self { + self.track_destab_signs = true; + self + } + + /// Whether destabilizer sign tracking is enabled. + #[inline] + pub fn tracks_destab_signs(&self) -> bool { + self.track_destab_signs + } + #[inline] pub fn reset(&mut self) -> &mut Self { self.stabs.init_all_z(); @@ -463,6 +483,10 @@ where S: IndexSet, R: SeedableRng + Rng + Debug, { + fn num_qubits(&self) -> usize { + self.num_qubits + } + #[inline] fn reset(&mut self) -> &mut Self { Self::reset(self) @@ -481,6 +505,9 @@ where for &q in qubits { let qu = q.index(); self.stabs.signs_minus.xor_assign(&self.stabs.col_z[qu]); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + } } self } @@ -493,6 +520,12 @@ where let qu = q.index(); self.stabs.col_x[qu] .xor_symmetric_difference_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.col_x[qu].xor_symmetric_difference_into( + &self.destabs.col_z[qu], + &mut self.destabs.signs_minus, + ); + } } self } @@ -505,6 +538,11 @@ where self.stabs .signs_minus .xor_assign(&self.stabs.col_x[q.index()]); + if self.track_destab_signs { + self.destabs + .signs_minus + .xor_assign(&self.destabs.col_x[q.index()]); + } } self } @@ -525,6 +563,10 @@ where // (both X and Z bits set). Y -> -X means the sign flips. self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } // Data update: same as W-convention (X bit implies Z bit gets toggled) for g in [&mut self.stabs, &mut self.destabs] { @@ -547,6 +589,10 @@ where self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } for g in [&mut self.stabs, &mut self.destabs] { for i in g.col_x[qu].iter() { @@ -578,6 +624,11 @@ where self.stabs.signs_minus.xor_assign(&self.stabs.col_x[qu]); self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } for g in [&mut self.stabs, &mut self.destabs] { g.col_z[qu].xor_assign(&g.col_x[qu]); for i in g.col_x[qu].iter() { @@ -597,6 +648,11 @@ where self.stabs.signs_minus.xor_assign(&self.stabs.col_z[qu]); self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } for g in [&mut self.stabs, &mut self.destabs] { g.col_x[qu].xor_assign(&g.col_z[qu]); for i in g.col_z[qu].iter() { @@ -615,6 +671,10 @@ where let qu = q.index(); self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } for g in [&mut self.stabs, &mut self.destabs] { g.col_x[qu].xor_assign(&g.col_z[qu]); for i in g.col_z[qu].iter() { @@ -634,6 +694,11 @@ where self.stabs.signs_minus.xor_assign(&self.stabs.col_x[qu]); self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_x[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } for g in [&mut self.stabs, &mut self.destabs] { for i in g.col_x[qu].iter() { if !g.col_z[qu].contains(i) { @@ -662,6 +727,11 @@ where self.stabs.signs_minus.xor_assign(&self.stabs.col_z[qu]); self.stabs.col_x[qu] .xor_intersection_into(&self.stabs.col_z[qu], &mut self.stabs.signs_minus); + if self.track_destab_signs { + self.destabs.signs_minus.xor_assign(&self.destabs.col_z[qu]); + self.destabs.col_x[qu] + .xor_intersection_into(&self.destabs.col_z[qu], &mut self.destabs.signs_minus); + } for g in [&mut self.stabs, &mut self.destabs] { for i in g.col_x[qu].iter() { if !g.col_z[qu].contains(i) { @@ -1054,7 +1124,7 @@ where let q2 = target.index(); debug_assert_ne!(q1, q2, "CX requires distinct qubits"); - // Y-convention sign update (only on stabs, not destabs) + // Y-convention sign update // Toggle signs_minus where: col_x[q1] AND col_z[q2] AND NOT(col_z[q1] XOR col_x[q2]) // = col_x[q1] AND col_z[q2] AND ((col_z[q1] AND col_x[q2]) OR (NOT col_z[q1] AND NOT col_x[q2])) // = (col_x[q1] AND col_z[q2] AND col_z[q1] AND col_x[q2]) OR (col_x[q1] AND col_z[q2] AND NOT col_z[q1] AND NOT col_x[q2]) @@ -1068,10 +1138,21 @@ where let has_z1 = self.stabs.col_z[q1].contains(g); let has_x2 = self.stabs.col_x[q2].contains(g); if has_z1 == has_x2 { - // NOT(z1 XOR x2) is true self.stabs.signs_minus.toggle(g); } } + if self.track_destab_signs { + for g in self.destabs.col_x[q1].iter() { + if !self.destabs.col_z[q2].contains(g) { + continue; + } + let has_z1 = self.destabs.col_z[q1].contains(g); + let has_x2 = self.destabs.col_x[q2].contains(g); + if has_z1 == has_x2 { + self.destabs.signs_minus.toggle(g); + } + } + } // Data update: identical to W-convention for g in &mut [&mut self.stabs, &mut self.destabs] { @@ -1109,7 +1190,7 @@ where let q2 = qb.index(); debug_assert_ne!(q1, q2, "SXX requires distinct qubits"); - // Sign update (stabs only): Q -> i*Q*XX. Per-qubit phase from + // Sign update: Q -> i*Q*XX. Per-qubit phase from // right-multiplying by X: Z*X=iY (c=+i), Y*X=-iZ (c=-i). // For odd-Z generators (z=1 at one qubit), total = i*c_q: // z=1 qubit is Z (x=0): i*(+i) = -1 -> toggle signs_minus @@ -1124,6 +1205,18 @@ where self.stabs.signs_minus.toggle(g); } } + if self.track_destab_signs { + for g in self.destabs.col_z[q1].iter() { + if !self.destabs.col_z[q2].contains(g) && !self.destabs.col_x[q1].contains(g) { + self.destabs.signs_minus.toggle(g); + } + } + for g in self.destabs.col_z[q2].iter() { + if !self.destabs.col_z[q1].contains(g) && !self.destabs.col_x[q2].contains(g) { + self.destabs.signs_minus.toggle(g); + } + } + } // Pauli update (both stabs and destabs): toggle X on q1,q2 for odd-Z generators. for tab in [&mut self.stabs, &mut self.destabs] { @@ -1285,14 +1378,35 @@ where for g in self.stabs.col_x[q2].iter() { if self.stabs.col_z[q2].contains(g) { continue; - } // skip Y, need X (x=1,z=0) + } let x1 = self.stabs.col_x[q1].contains(g); let z1 = self.stabs.col_z[q1].contains(g); if x1 == z1 { - // q1 commutes with Y -> toggle self.stabs.signs_minus.toggle(g); } } + if self.track_destab_signs { + for g in self.destabs.col_x[q1].iter() { + if self.destabs.col_z[q1].contains(g) { + continue; + } + let x2 = self.destabs.col_x[q2].contains(g); + let z2 = self.destabs.col_z[q2].contains(g); + if x2 == z2 { + self.destabs.signs_minus.toggle(g); + } + } + for g in self.destabs.col_x[q2].iter() { + if self.destabs.col_z[q2].contains(g) { + continue; + } + let x1 = self.destabs.col_x[q1].contains(g); + let z1 = self.destabs.col_z[q1].contains(g); + if x1 == z1 { + self.destabs.signs_minus.toggle(g); + } + } + } for tab in [&mut self.stabs, &mut self.destabs] { unsafe { @@ -1429,10 +1543,6 @@ where fn destab_tableau(&self) -> String { Self::tableau_string(self.num_qubits, &self.destabs) } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } // ForcedMeasurement and StabilizerSimulator implementations diff --git a/crates/pecos-simulators/src/clifford_rz.rs b/crates/pecos-simulators/src/stab_vec.rs similarity index 95% rename from crates/pecos-simulators/src/clifford_rz.rs rename to crates/pecos-simulators/src/stab_vec.rs index bad187847..11ee8cbcb 100644 --- a/crates/pecos-simulators/src/clifford_rz.rs +++ b/crates/pecos-simulators/src/stab_vec.rs @@ -59,10 +59,10 @@ use pecos_random::{PecosRng, Rng, RngExt, SeedableRng}; /// The pruning threshold can be configured via the builder: /// /// ``` -/// use pecos_simulators::CliffordRz; +/// use pecos_simulators::StabVec; /// /// let num_qubits = 4; -/// let sim = CliffordRz::builder(num_qubits) +/// let sim = StabVec::builder(num_qubits) /// .pruning_threshold(1e-6) /// .seed(42) /// .build(); @@ -71,7 +71,7 @@ use pecos_random::{PecosRng, Rng, RngExt, SeedableRng}; use crate::clifford_frame::{CliffordFrame, GEN_LENS, GENERATORS, PHASE_COCYCLE}; #[derive(Clone, Debug)] -pub struct CliffordRzGeneric { +pub struct StabVecGeneric { num_qubits: usize, terms: Vec<(Complex64, CHFormGeneric)>, /// Pending RZ angles per qubit. @@ -93,17 +93,17 @@ pub struct CliffordRzGeneric = CliffordRzGeneric; +pub type StabVec = StabVecGeneric; -/// Builder for configuring a `CliffordRz` simulator. -pub struct CliffordRzBuilder { +/// Builder for configuring a `StabVec` simulator. +pub struct StabVecBuilder { num_qubits: usize, seed: Option, rel_pruning_threshold: f64, mc_threshold: Option, } -impl CliffordRzBuilder { +impl StabVecBuilder { /// Set the pruning threshold. Terms with |c|^2 < threshold * max(|c|^2) are pruned. /// /// - Default: 1e-8 (conservative, safe for precision work like QEC) @@ -135,14 +135,14 @@ impl CliffordRzBuilder { /// Build the simulator. #[must_use] - pub fn build(self) -> CliffordRz { + pub fn build(self) -> StabVec { let rng = if let Some(seed) = self.seed { PecosRng::seed_from_u64(seed) } else { rand::make_rng() }; let ch = CHFormGeneric::with_rng(self.num_qubits, rng.clone()); - CliffordRzGeneric { + StabVecGeneric { num_qubits: self.num_qubits, terms: vec![(Complex64::new(1.0, 0.0), ch)], pending_rz: vec![Angle64::default(); self.num_qubits], @@ -156,7 +156,7 @@ impl CliffordRzBuilder { } } -impl CliffordRzGeneric { +impl StabVecGeneric { /// Recompute `gamma_diff_qubits` from the actual surviving terms. /// Only keeps qubits where gamma genuinely differs across at least one pair. fn recompute_gamma_diff(&mut self) { @@ -941,11 +941,11 @@ impl CliffordRzGeneric // Constructors for default types // ============================================================================ -impl CliffordRzGeneric { +impl StabVecGeneric { /// Create a builder for configuring the simulator. #[must_use] - pub fn builder(num_qubits: usize) -> CliffordRzBuilder { - CliffordRzBuilder { + pub fn builder(num_qubits: usize) -> StabVecBuilder { + StabVecBuilder { num_qubits, seed: None, rel_pruning_threshold: 1e-8, @@ -971,9 +971,11 @@ impl CliffordRzGeneric { // Trait implementations // ============================================================================ -impl QuantumSimulator - for CliffordRzGeneric -{ +impl QuantumSimulator for StabVecGeneric { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { let rng = self.rng.clone(); let ch = CHFormGeneric::with_rng(self.num_qubits, rng); @@ -984,9 +986,7 @@ impl QuantumSimulator } } -impl CliffordGateable - for CliffordRzGeneric -{ +impl CliffordGateable for StabVecGeneric { // === Single-qubit Cliffords: all compose into the frame in O(1) === // Diagonal gates (Z, S, Sdg) commute with pending_rz. // Non-diagonal gates (H, X, Y, SX, etc.) negate pending_rz if they @@ -1356,7 +1356,7 @@ impl CliffordGateable } impl ArbitraryRotationGateable - for CliffordRzGeneric + for StabVecGeneric { fn rx(&mut self, theta: Angle64, qubits: &[QubitId]) -> &mut Self { // RX = H * RZ * H. Use frame-aware H and RZ. @@ -1430,7 +1430,7 @@ impl ArbitraryRotationGateabl } impl pecos_core::RngManageable - for CliffordRzGeneric + for StabVecGeneric { type Rng = R; @@ -1485,8 +1485,8 @@ mod tests { } #[test] - fn test_clifford_rz_initial_state() { - let mut sim = CliffordRz::new(2); + fn test_stab_vec_initial_state() { + let mut sim = StabVec::new(2); assert_eq!(sim.num_terms(), 1); let sv = sim.state_vector(); assert!((sv[0] - Complex64::new(1.0, 0.0)).norm() < EPS); @@ -1495,7 +1495,7 @@ mod tests { #[test] fn test_clifford_only_matches_statevec() { - let mut crz = CliffordRz::new(2); + let mut crz = StabVec::new(2); let mut sv = StateVec::new(2); // Apply Clifford circuit @@ -1508,7 +1508,7 @@ mod tests { #[test] fn test_single_rz_doubles_terms() { - let mut crz = CliffordRz::new(1); + let mut crz = StabVec::new(1); crz.h(&qid(0)); assert_eq!(crz.num_terms(), 1); @@ -1522,7 +1522,7 @@ mod tests { #[test] fn test_rz_matches_statevec() { - let mut crz = CliffordRz::new(1); + let mut crz = StabVec::new(1); let mut sv = StateVec::new(1); let theta = Angle64::from_radians(0.7); @@ -1534,7 +1534,7 @@ mod tests { #[test] fn test_t_gate_matches_statevec() { - let mut crz = CliffordRz::new(1); + let mut crz = StabVec::new(1); let mut sv = StateVec::new(1); // T gate = RZ(pi/4) @@ -1547,7 +1547,7 @@ mod tests { #[test] fn test_multiple_rz_matches_statevec() { - let mut crz = CliffordRz::new(2); + let mut crz = StabVec::new(2); let mut sv = StateVec::new(2); let theta1 = Angle64::from_radians(0.5); @@ -1568,7 +1568,7 @@ mod tests { #[test] fn test_rx_matches_statevec() { - let mut crz = CliffordRz::new(1); + let mut crz = StabVec::new(1); let mut sv = StateVec::new(1); let theta = Angle64::from_radians(0.9); @@ -1580,7 +1580,7 @@ mod tests { #[test] fn test_rzz_matches_statevec() { - let mut crz = CliffordRz::new(2); + let mut crz = StabVec::new(2); let mut sv = StateVec::new(2); let theta = Angle64::from_radians(0.6); @@ -1595,8 +1595,8 @@ mod tests { } #[test] - fn test_mixed_clifford_rz_circuit() { - let mut crz = CliffordRz::new(2); + fn test_mixed_stab_vec_circuit() { + let mut crz = StabVec::new(2); let mut sv = StateVec::new(2); let theta = Angle64::from_radians(0.4); @@ -1617,25 +1617,25 @@ mod tests { #[test] fn test_rz_clifford_angle_stays_one_term() { // RZ(0) = I: no term growth - let mut crz = CliffordRz::new(1); + let mut crz = StabVec::new(1); crz.h(&qid(0)); crz.rz(Angle64::from_radians(0.0), &qid(0)); assert_eq!(crz.num_terms(), 1); // RZ(pi) = -iZ: no term growth - let mut crz2 = CliffordRz::new(1); + let mut crz2 = StabVec::new(1); crz2.h(&qid(0)); crz2.rz(Angle64::from_radians(std::f64::consts::PI), &qid(0)); assert_eq!(crz2.num_terms(), 1, "RZ(pi) should not add terms"); // RZ(pi/2) = e^{-i*pi/4} S: no term growth - let mut crz3 = CliffordRz::new(1); + let mut crz3 = StabVec::new(1); crz3.h(&qid(0)); crz3.rz(Angle64::from_radians(std::f64::consts::FRAC_PI_2), &qid(0)); assert_eq!(crz3.num_terms(), 1, "RZ(pi/2) should not add terms"); // RZ(-pi/2) = e^{i*pi/4} Sdg: no term growth - let mut crz4 = CliffordRz::new(1); + let mut crz4 = StabVec::new(1); crz4.h(&qid(0)); crz4.rz(Angle64::from_radians(-std::f64::consts::FRAC_PI_2), &qid(0)); assert_eq!(crz4.num_terms(), 1, "RZ(-pi/2) should not add terms"); @@ -1647,7 +1647,7 @@ mod tests { #[test] fn test_measurement_deterministic_zero_state() { - let mut crz = CliffordRz::new_with_seed(1, 42); + let mut crz = StabVec::new_with_seed(1, 42); let results = crz.mz(&qid(0)); assert!(results[0].is_deterministic); assert!(!results[0].outcome); // |0> @@ -1656,7 +1656,7 @@ mod tests { #[test] fn test_measurement_after_rz() { // RZ(theta) on |0> gives e^{-i*theta/2}|0> -- still deterministic |0> - let mut crz = CliffordRz::new_with_seed(1, 42); + let mut crz = StabVec::new_with_seed(1, 42); let theta = Angle64::from_radians(0.7); crz.rz(theta, &qid(0)); let results = crz.mz(&qid(0)); @@ -1667,7 +1667,7 @@ mod tests { #[test] fn test_measurement_after_h_rz() { // H|0> then RZ should give non-deterministic measurement - let mut crz = CliffordRz::new_with_seed(1, 42); + let mut crz = StabVec::new_with_seed(1, 42); let theta = Angle64::from_radians(0.5); crz.h(&qid(0)).rz(theta, &qid(0)); let results = crz.mz(&qid(0)); @@ -1693,7 +1693,7 @@ mod tests { let mut count0 = 0; for seed in 0..num_shots { - let mut crz = CliffordRz::new_with_seed(1, seed); + let mut crz = StabVec::new_with_seed(1, seed); crz.rx(theta, &qid(0)); let results = crz.mz(&qid(0)); if !results[0].outcome { @@ -1715,7 +1715,7 @@ mod tests { // Create Bell state, apply RZ on q0, measure both. // After measuring q0, q1 outcome should be correlated. let theta = Angle64::from_radians(0.6); - let mut crz = CliffordRz::new_with_seed(2, 42); + let mut crz = StabVec::new_with_seed(2, 42); crz.h(&qid(0)) .cx(&[(QubitId(0), QubitId(1))]) .rz(theta, &qid(0)); @@ -1752,7 +1752,7 @@ mod tests { // Second measurement should be non-deterministic (50/50). let theta = Angle64::from_radians(0.5); - let mut crz = CliffordRz::new_with_seed(1, 42); + let mut crz = StabVec::new_with_seed(1, 42); crz.h(&qid(0)).rz(theta, &qid(0)); // Force measurement outcome to 0 @@ -1781,7 +1781,7 @@ mod tests { #[test] fn test_three_qubit_circuit() { - let mut crz = CliffordRz::new(3); + let mut crz = StabVec::new(3); let mut sv = StateVec::new(3); let theta = Angle64::from_radians(0.8); @@ -1801,7 +1801,7 @@ mod tests { #[test] fn test_reset() { - let mut crz = CliffordRz::new(2); + let mut crz = StabVec::new(2); let theta = Angle64::from_radians(0.5); crz.h(&qid(0)).rz(theta, &qid(0)); crz.flush_all_pending_rz(); @@ -1816,7 +1816,7 @@ mod tests { #[test] fn test_rz_at_clifford_angles_vs_statevec() { // RZ(pi/2) should be equivalent to S (up to global phase) - let mut crz = CliffordRz::new(1); + let mut crz = StabVec::new(1); let mut sv = StateVec::new(1); let half_pi = Angle64::from_radians(std::f64::consts::FRAC_PI_2); crz.h(&qid(0)).rz(half_pi, &qid(0)); @@ -1824,7 +1824,7 @@ mod tests { states_match_up_to_phase(&crz.state_vector(), &sv.state(), "rz_pi_2"); // RZ(pi) should be equivalent to Z (up to global phase) - let mut crz2 = CliffordRz::new(1); + let mut crz2 = StabVec::new(1); let mut sv2 = StateVec::new(1); let pi = Angle64::from_radians(std::f64::consts::PI); crz2.h(&qid(0)).rz(pi, &qid(0)); @@ -1835,7 +1835,7 @@ mod tests { #[test] fn test_many_rz_gates() { // 5 RZ gates -> 32 terms. Verify state still matches StateVec. - let mut crz = CliffordRz::new(2); + let mut crz = StabVec::new(2); let mut sv = StateVec::new(2); let angles: Vec = [0.3, 0.7, 1.1, 0.5, 0.9] @@ -1877,12 +1877,12 @@ mod tests { #[test] fn test_measurement_probability_matches_statevec() { - // Compare exact measurement probabilities between CliffordRz and StateVec. + // Compare exact measurement probabilities between StabVec and StateVec. // Circuit: H(0) - CX(0,1) - RZ(0.8, q0) - H(1) // Then compute Pr(q0=0) and Pr(q1=0) from both simulators. let theta = Angle64::from_radians(0.8); - let mut crz = CliffordRz::new(2); + let mut crz = StabVec::new(2); let mut sv = StateVec::new(2); crz.h(&qid(0)) @@ -1923,7 +1923,7 @@ mod tests { // After forced measurement, compare the projected state vectors. let theta = Angle64::from_radians(0.6); - let mut crz = CliffordRz::new(2); + let mut crz = StabVec::new(2); let mut sv = StateVec::new(2); crz.h(&qid(0)) @@ -1933,7 +1933,7 @@ mod tests { .cx(&[(QubitId(0), QubitId(1))]) .rz(theta, &qid(0)); - // Force q0 = 0 on CliffordRz + // Force q0 = 0 on StabVec crz.measure_qubit(0, Some(false)); // For StateVec, project manually: zero out amplitudes where q0=1, renormalize @@ -1958,7 +1958,7 @@ mod tests { // 3-qubit circuit: measure q0, verify q1 and q2 state is correct. let theta = Angle64::from_radians(0.5); - let mut crz = CliffordRz::new(3); + let mut crz = StabVec::new(3); let mut sv = StateVec::new(3); // Prepare: H(0) CX(0,1) RZ(q2) -- q2 is independent @@ -1971,7 +1971,7 @@ mod tests { .h(&qid(2)) .rz(theta, &qid(2)); - // Force q0 = 0 on CliffordRz + // Force q0 = 0 on StabVec crz.measure_qubit(0, Some(false)); // Project StateVec manually: zero amplitudes where q0=1, renormalize @@ -2010,10 +2010,10 @@ mod tests { .map(num_complex::Complex::norm_sqr) .collect(); - // Sample from CliffordRz + // Sample from StabVec let mut counts = [0u32; 4]; for seed in 0..num_shots { - let mut crz = CliffordRz::new_with_seed(2, seed); + let mut crz = StabVec::new_with_seed(2, seed); crz.h(&qid(0)) .rz(theta, &qid(0)) .cx(&[(QubitId(0), QubitId(1))]); @@ -2037,7 +2037,7 @@ mod tests { fn test_ry_gate() { // RY uses default decomposition: Sdg RX Sz. // RX uses our H RZ H. So this tests the full chain. - let mut crz = CliffordRz::new(1); + let mut crz = StabVec::new(1); let mut sv = StateVec::new(1); let theta = Angle64::from_radians(1.2); @@ -2055,7 +2055,7 @@ mod tests { // State vector should have amp[0] = e^{-i*theta/2}, amp[1] = 0. let theta = Angle64::from_radians(0.8); - let mut crz = CliffordRz::new_with_seed(1, 42); + let mut crz = StabVec::new_with_seed(1, 42); crz.h(&qid(0)); crz.measure_qubit(0, Some(false)); crz.rz(theta, &qid(0)); @@ -2079,7 +2079,7 @@ mod tests { let theta1 = Angle64::from_radians(0.5); let theta2 = Angle64::from_radians(0.9); - let mut crz = CliffordRz::new_with_seed(1, 42); + let mut crz = StabVec::new_with_seed(1, 42); crz.h(&qid(0)).rz(theta1, &qid(0)); crz.measure_qubit(0, Some(false)); // After projecting to |0>, apply H -> RZ @@ -2114,8 +2114,8 @@ mod tests { .map(num_complex::Complex::norm_sqr) .collect(); - // Verify CliffordRz state matches before measurement - let mut crz = CliffordRz::new(2); + // Verify StabVec state matches before measurement + let mut crz = StabVec::new(2); crz.h(&qid(0)) .h(&qid(1)) .rzz(theta, &[(QubitId(0), QubitId(1))]); @@ -2125,7 +2125,7 @@ mod tests { let num_shots = 5000; let mut counts = [0u32; 4]; for seed in 0..num_shots { - let mut crz = CliffordRz::new_with_seed(2, seed); + let mut crz = StabVec::new_with_seed(2, seed); crz.h(&qid(0)) .h(&qid(1)) .rzz(theta, &[(QubitId(0), QubitId(1))]); @@ -2147,8 +2147,8 @@ mod tests { #[test] fn test_5_qubit_circuit() { - // Verify CliffordRz works at 5 qubits with entanglement and RZ gates. - let mut crz = CliffordRz::new(5); + // Verify StabVec works at 5 qubits with entanglement and RZ gates. + let mut crz = StabVec::new(5); let mut sv = StateVec::new(5); let theta1 = Angle64::from_radians(0.4); @@ -2176,7 +2176,7 @@ mod tests { // Measure all 5 qubits after Clifford+RZ circuit, verify normalization. let theta = Angle64::from_radians(0.6); - let mut crz = CliffordRz::new_with_seed(5, 42); + let mut crz = StabVec::new_with_seed(5, 42); crz.h(&[QubitId(0)]) .cx(&[(QubitId(0), QubitId(1))]) .cx(&[(QubitId(1), QubitId(2))]) @@ -2206,7 +2206,7 @@ mod tests { #[test] fn test_builder_default() { - let mut sim = CliffordRz::builder(2).build(); + let mut sim = StabVec::builder(2).build(); sim.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); let sv = sim.state_vector(); let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; @@ -2215,8 +2215,8 @@ mod tests { #[test] fn test_builder_with_seed() { - let mut sim1 = CliffordRz::builder(1).seed(42).build(); - let mut sim2 = CliffordRz::builder(1).seed(42).build(); + let mut sim1 = StabVec::builder(1).seed(42).build(); + let mut sim2 = StabVec::builder(1).seed(42).build(); sim1.h(&qid(0)); sim2.h(&qid(0)); let r1 = sim1.mz(&qid(0)); @@ -2231,10 +2231,7 @@ mod tests { fn test_builder_exact_mode() { // With threshold=0 (exact mode), no terms are pruned even for small angles. let theta = Angle64::from_radians(0.001); - let mut sim = CliffordRz::builder(1) - .pruning_threshold(0.0) - .seed(42) - .build(); + let mut sim = StabVec::builder(1).pruning_threshold(0.0).seed(42).build(); sim.h(&qid(0)); for _ in 0..8 { sim.rz(theta, &qid(0)); @@ -2249,10 +2246,7 @@ mod tests { fn test_builder_aggressive_pruning() { // With aggressive pruning, small-angle terms are removed faster. let theta = Angle64::from_radians(5.0f64.to_radians()); - let mut sim = CliffordRz::builder(4) - .pruning_threshold(1e-4) - .seed(42) - .build(); + let mut sim = StabVec::builder(4).pruning_threshold(1e-4).seed(42).build(); for q in 0..4 { sim.h(&[QubitId(q)]); } @@ -2271,7 +2265,7 @@ mod tests { #[test] fn test_pz_prep() { // X|0> = |1>, then PZ resets to |0> - let mut crz = CliffordRz::new(1); + let mut crz = StabVec::new(1); crz.x(&qid(0)); crz.pz(&qid(0)); let results = crz.mz(&qid(0)); @@ -2281,7 +2275,7 @@ mod tests { #[test] fn test_rxx_matches_statevec() { - let mut crz = CliffordRz::new(2); + let mut crz = StabVec::new(2); let mut sv = StateVec::new(2); let theta = Angle64::from_radians(0.7); crz.h(&qid(0)) @@ -2295,7 +2289,7 @@ mod tests { #[test] fn test_ryy_matches_statevec() { - let mut crz = CliffordRz::new(2); + let mut crz = StabVec::new(2); let mut sv = StateVec::new(2); let theta = Angle64::from_radians(0.9); crz.h(&qid(0)) @@ -2310,10 +2304,7 @@ mod tests { #[test] fn test_exact_mode_matches_statevec() { // With pruning_threshold=0, results should match StateVec exactly (up to phase). - let mut crz = CliffordRz::builder(2) - .pruning_threshold(0.0) - .seed(42) - .build(); + let mut crz = StabVec::builder(2).pruning_threshold(0.0).seed(42).build(); let mut sv = StateVec::new(2); let theta = Angle64::from_radians(0.3); crz.h(&qid(0)) @@ -2333,13 +2324,13 @@ mod tests { // Qubit range coverage tests // ======================================================================== - /// Test `CliffordRz` at qubit counts that exercise the pairwise inner product + /// Test `StabVec` at qubit counts that exercise the pairwise inner product /// measurement path (n>6) and various `ExponentialSum` tiers. #[test] - fn test_clifford_rz_medium_qubit_counts() { + fn test_stab_vec_medium_qubit_counts() { // These exercise: n>6 pairwise measurement, ExponentialSum d>3 path for nq in [8, 10, 14, 20] { - let mut crz = CliffordRz::new_with_seed(nq, 42); + let mut crz = StabVec::new_with_seed(nq, 42); let mut sv = StateVec::new(nq); let theta = Angle64::from_radians(0.5); @@ -2369,7 +2360,7 @@ mod tests { let mut crz_p0_sum = 0.0; let nshots = 5000; for seed in 0..nshots { - let mut crz = CliffordRz::new_with_seed(nq, seed); + let mut crz = StabVec::new_with_seed(nq, seed); for q in 0..nq { crz.h(&[QubitId(q)]); } @@ -2405,7 +2396,7 @@ mod tests { let crz_p0 = crz_p0_sum / nshots as f64; assert!( (crz_p0 - sv_p0).abs() < 0.05, - "nrz={nrz}: Pr(q0=0) CliffordRz={crz_p0:.3} vs StateVec={sv_p0:.3}" + "nrz={nrz}: Pr(q0=0) StabVec={crz_p0:.3} vs StateVec={sv_p0:.3}" ); } } @@ -2417,7 +2408,7 @@ mod tests { let nq = 8; let theta = Angle64::from_radians(0.4); for nrz in [3, 4, 5] { - let mut crz = CliffordRz::new_with_seed(nq, 42); + let mut crz = StabVec::new_with_seed(nq, 42); for q in 0..nq { crz.h(&[QubitId(q)]); } @@ -2436,11 +2427,11 @@ mod tests { } #[test] - fn test_clifford_rz_measurement_at_pairwise_threshold() { + fn test_stab_vec_measurement_at_pairwise_threshold() { // n=7 (state vector path) and n=8 (pairwise path) should both work for nq in [6, 7, 8] { let theta = Angle64::from_radians(0.5); - let mut crz = CliffordRz::new_with_seed(nq, 42); + let mut crz = StabVec::new_with_seed(nq, 42); for q in 0..nq { crz.h(&[QubitId(q)]); } @@ -2451,10 +2442,10 @@ mod tests { } #[test] - fn test_clifford_rz_at_u64_boundary() { + fn test_stab_vec_at_u64_boundary() { // n=62 (last u64 ExponentialSum) -- verify measurement works let nq = 62; - let mut crz = CliffordRz::new_with_seed(nq, 42); + let mut crz = StabVec::new_with_seed(nq, 42); for q in 0..nq { crz.h(&[QubitId(q)]); } @@ -2464,10 +2455,10 @@ mod tests { } #[test] - fn test_clifford_rz_at_u128_boundary() { + fn test_stab_vec_at_u128_boundary() { // n=63 (first u128 ExponentialSum) -- verify measurement works let nq = 63; - let mut crz = CliffordRz::new_with_seed(nq, 42); + let mut crz = StabVec::new_with_seed(nq, 42); for q in 0..nq { crz.h(&[QubitId(q)]); } @@ -2479,7 +2470,7 @@ mod tests { #[test] fn test_ry_simple() { // Just H then RY on 1 qubit - let mut crz = CliffordRz::new(1); + let mut crz = StabVec::new(1); let mut sv = StateVec::new(1); crz.h(&qid(0)); sv.h(&qid(0)); @@ -2491,7 +2482,7 @@ mod tests { #[test] fn test_ry_on_zero() { // RY on |0> should match statevec - let mut crz = CliffordRz::new(1); + let mut crz = StabVec::new(1); let mut sv = StateVec::new(1); crz.ry(Angle64::from_radians(0.3), &qid(0)); sv.ry(Angle64::from_radians(0.3), &qid(0)); @@ -2501,7 +2492,7 @@ mod tests { #[test] fn test_engine_circuit_statevec_match() { // Reproduce the engine round-trip circuit: H, CX, RZ, H, RY, CZ, RX - let mut crz = CliffordRz::new(3); + let mut crz = StabVec::new(3); let mut sv = StateVec::new(3); crz.h(&[QubitId(0), QubitId(1), QubitId(2)]); diff --git a/crates/pecos-simulators/src/clifford_rz/ch_form.rs b/crates/pecos-simulators/src/stab_vec/ch_form.rs similarity index 100% rename from crates/pecos-simulators/src/clifford_rz/ch_form.rs rename to crates/pecos-simulators/src/stab_vec/ch_form.rs index fd788a3f2..e96393dbe 100644 --- a/crates/pecos-simulators/src/clifford_rz/ch_form.rs +++ b/crates/pecos-simulators/src/stab_vec/ch_form.rs @@ -2074,6 +2074,10 @@ impl CHFormGeneric { // ============================================================================ impl QuantumSimulator for CHFormGeneric { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { self.init(); self @@ -2420,10 +2424,6 @@ impl StabilizerTableauSimulator for C } lines.join("\n") } - - fn num_qubits(&self) -> usize { - self.num_qubits - } } // ============================================================================ diff --git a/crates/pecos-simulators/src/clifford_rz/exact_scalar.rs b/crates/pecos-simulators/src/stab_vec/exact_scalar.rs similarity index 100% rename from crates/pecos-simulators/src/clifford_rz/exact_scalar.rs rename to crates/pecos-simulators/src/stab_vec/exact_scalar.rs diff --git a/crates/pecos-simulators/src/clifford_rz/quadratic_form.rs b/crates/pecos-simulators/src/stab_vec/quadratic_form.rs similarity index 100% rename from crates/pecos-simulators/src/clifford_rz/quadratic_form.rs rename to crates/pecos-simulators/src/stab_vec/quadratic_form.rs diff --git a/crates/pecos-simulators/src/clifford_rz/sparse_binary_matrix.rs b/crates/pecos-simulators/src/stab_vec/sparse_binary_matrix.rs similarity index 100% rename from crates/pecos-simulators/src/clifford_rz/sparse_binary_matrix.rs rename to crates/pecos-simulators/src/stab_vec/sparse_binary_matrix.rs diff --git a/crates/pecos-simulators/src/stabilizer.rs b/crates/pecos-simulators/src/stabilizer.rs index a492ea9ac..b1e1b5bc6 100644 --- a/crates/pecos-simulators/src/stabilizer.rs +++ b/crates/pecos-simulators/src/stabilizer.rs @@ -115,6 +115,10 @@ impl Stabilizer { } impl QuantumSimulator for Stabilizer { + fn num_qubits(&self) -> usize { + self.inner.num_qubits() + } + #[inline] fn reset(&mut self) -> &mut Self { self.inner.reset(); @@ -220,10 +224,6 @@ impl StabilizerTableauSimulator for Stabilizer { fn destab_tableau(&self) -> String { self.inner.destab_tableau() } - - fn num_qubits(&self) -> usize { - self.inner.num_qubits() - } } // ============================================================================ diff --git a/crates/pecos-simulators/src/stabilizer_tableau.rs b/crates/pecos-simulators/src/stabilizer_tableau.rs index 78244050b..c55e95128 100644 --- a/crates/pecos-simulators/src/stabilizer_tableau.rs +++ b/crates/pecos-simulators/src/stabilizer_tableau.rs @@ -89,10 +89,4 @@ pub trait StabilizerTableauSimulator: QuantumSimulator { self.stab_tableau() ) } - - /// Returns the number of qubits in the simulator. - /// - /// This method should be implemented by each simulator type to return - /// the number of qubits being simulated. - fn num_qubits(&self) -> usize; } diff --git a/crates/pecos-simulators/src/state_vec_aos.rs b/crates/pecos-simulators/src/state_vec_aos.rs index 85b25e41a..9a69c1a3d 100644 --- a/crates/pecos-simulators/src/state_vec_aos.rs +++ b/crates/pecos-simulators/src/state_vec_aos.rs @@ -444,6 +444,10 @@ impl QuantumSimulator for StateVecAoS where R: Rng + SeedableRng + Debug, { + fn num_qubits(&self) -> usize { + self.num_qubits + } + /// # Examples /// ```rust /// use pecos_simulators::{QuantumSimulator, StateVecAoS}; diff --git a/crates/pecos-simulators/src/state_vec_soa.rs b/crates/pecos-simulators/src/state_vec_soa.rs index 8d284b329..0676a86f4 100644 --- a/crates/pecos-simulators/src/state_vec_soa.rs +++ b/crates/pecos-simulators/src/state_vec_soa.rs @@ -2814,6 +2814,10 @@ impl QuantumSimulator for StateVecSoA where R: Rng, { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { // Clear pending gates (state is being reset anyway) for pg in &mut self.pending_gates { @@ -4438,11 +4442,11 @@ where results } - /// Optimized measure-and-prepare-Z: always prepares |0⟩ state. + /// Optimized measure-and-prepare-Z: measures qubit, then prepares |0⟩. /// - /// This is more efficient than the default implementation because it: - /// 1. Always collapses to |0⟩ regardless of measurement outcome - /// 2. Avoids the conditional X correction step + /// Fuses projection + conditional X into a single pass over the state vector: + /// - outcome 0: zero |1⟩ amplitudes, normalize |0⟩ (already in |0⟩) + /// - outcome 1: move |1⟩ amplitudes to |0⟩ positions with normalization, zero |1⟩ #[inline] fn mpz(&mut self, qubits: &[QubitId]) -> Vec { self.flush(); @@ -4452,28 +4456,37 @@ where let q_idx = q.index(); let step = 1 << q_idx; - // Calculate probability of measuring |1⟩ let prob_one = self.probability_one(q_idx); - - // Sample outcome (for the measurement result) let outcome = self.rng.bernoulli(prob_one); let is_deterministic = !(1e-10..=1.0 - 1e-10).contains(&prob_one); - // Always prepare |0⟩: zero the |1⟩ amplitudes and normalize |0⟩ - let norm_factor = 1.0 / (1.0 - prob_one).sqrt(); + let norm_factor = if outcome { + 1.0 / prob_one.sqrt() + } else { + 1.0 / (1.0 - prob_one).sqrt() + }; if step < 4 { // Scalar path for i in (0..self.real.len()).step_by(step * 2) { - // Normalize |0⟩ states - for j in i..(i + step) { - self.real[j] *= norm_factor; - self.imag[j] *= norm_factor; - } - // Zero |1⟩ states - for j in (i + step)..(i + 2 * step) { - self.real[j] = 0.0; - self.imag[j] = 0.0; + if outcome { + // Move |1⟩ -> |0⟩ with normalization, zero |1⟩ + for j in 0..step { + self.real[i + j] = self.real[i + step + j] * norm_factor; + self.imag[i + j] = self.imag[i + step + j] * norm_factor; + self.real[i + step + j] = 0.0; + self.imag[i + step + j] = 0.0; + } + } else { + // Normalize |0⟩, zero |1⟩ + for j in 0..step { + self.real[i + j] *= norm_factor; + self.imag[i + j] *= norm_factor; + } + for j in (i + step)..(i + 2 * step) { + self.real[j] = 0.0; + self.imag[j] = 0.0; + } } } } else { @@ -4481,23 +4494,40 @@ where let norm_vec = f64x4::splat(norm_factor); for i in (0..self.real.len()).step_by(step * 2) { - // Normalize |0⟩ states - let mut j = i; - while j + 4 <= i + step { - let re = f64x4::from(&self.real[j..j + 4]); - let im = f64x4::from(&self.imag[j..j + 4]); - let scaled_re: [f64; 4] = (norm_vec * re).into(); - let scaled_im: [f64; 4] = (norm_vec * im).into(); - self.real[j..j + 4].copy_from_slice(&scaled_re); - self.imag[j..j + 4].copy_from_slice(&scaled_im); - j += 4; - } - // Zero |1⟩ states - let mut j = i + step; - while j + 4 <= i + 2 * step { - self.real[j..j + 4].copy_from_slice(&[0.0; 4]); - self.imag[j..j + 4].copy_from_slice(&[0.0; 4]); - j += 4; + if outcome { + // Move |1⟩ -> |0⟩ with normalization, zero |1⟩ + let mut j = 0; + while j + 4 <= step { + let re = f64x4::from(&self.real[i + step + j..i + step + j + 4]); + let im = f64x4::from(&self.imag[i + step + j..i + step + j + 4]); + let scaled_re: [f64; 4] = (norm_vec * re).into(); + let scaled_im: [f64; 4] = (norm_vec * im).into(); + self.real[i + j..i + j + 4].copy_from_slice(&scaled_re); + self.imag[i + j..i + j + 4].copy_from_slice(&scaled_im); + self.real[i + step + j..i + step + j + 4] + .copy_from_slice(&[0.0; 4]); + self.imag[i + step + j..i + step + j + 4] + .copy_from_slice(&[0.0; 4]); + j += 4; + } + } else { + // Normalize |0⟩, zero |1⟩ + let mut j = i; + while j + 4 <= i + step { + let re = f64x4::from(&self.real[j..j + 4]); + let im = f64x4::from(&self.imag[j..j + 4]); + let scaled_re: [f64; 4] = (norm_vec * re).into(); + let scaled_im: [f64; 4] = (norm_vec * im).into(); + self.real[j..j + 4].copy_from_slice(&scaled_re); + self.imag[j..j + 4].copy_from_slice(&scaled_im); + j += 4; + } + let mut j = i + step; + while j + 4 <= i + 2 * step { + self.real[j..j + 4].copy_from_slice(&[0.0; 4]); + self.imag[j..j + 4].copy_from_slice(&[0.0; 4]); + j += 4; + } } } } diff --git a/crates/pecos-simulators/src/state_vec_soa32.rs b/crates/pecos-simulators/src/state_vec_soa32.rs index 54b14bb83..7dad3a055 100644 --- a/crates/pecos-simulators/src/state_vec_soa32.rs +++ b/crates/pecos-simulators/src/state_vec_soa32.rs @@ -938,6 +938,10 @@ impl QuantumSimulator for StateVecSoA32 where R: Rng, { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { self.real.fill(0.0); self.imag.fill(0.0); diff --git a/crates/pecos-simulators/src/state_vec_sparse_aos.rs b/crates/pecos-simulators/src/state_vec_sparse_aos.rs index 38fe0e019..193c215dd 100644 --- a/crates/pecos-simulators/src/state_vec_sparse_aos.rs +++ b/crates/pecos-simulators/src/state_vec_sparse_aos.rs @@ -843,6 +843,10 @@ impl SparseStateVecAoS { // ============================================================================= impl QuantumSimulator for SparseStateVecAoS { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { self.amplitudes.clear(); self.amplitudes.push((0, Complex64::new(1.0, 0.0))); diff --git a/crates/pecos-simulators/src/state_vec_sparse_soa.rs b/crates/pecos-simulators/src/state_vec_sparse_soa.rs index 25206e191..6a75f429b 100644 --- a/crates/pecos-simulators/src/state_vec_sparse_soa.rs +++ b/crates/pecos-simulators/src/state_vec_sparse_soa.rs @@ -1915,6 +1915,10 @@ impl SparseStateVecSoA { // --- QuantumSimulator trait implementation --- impl QuantumSimulator for SparseStateVecSoA { + fn num_qubits(&self) -> usize { + self.num_qubits + } + fn reset(&mut self) -> &mut Self { // Reset to |0⟩ state in buffer A self.indices_a.clear(); diff --git a/crates/pecos-simulators/src/state_vector_test_utils.rs b/crates/pecos-simulators/src/state_vector_test_utils.rs index 6d45bf074..914cb6536 100644 --- a/crates/pecos-simulators/src/state_vector_test_utils.rs +++ b/crates/pecos-simulators/src/state_vector_test_utils.rs @@ -57,9 +57,6 @@ pub trait StateVectorSimulator: CliffordGateable + QuantumSimulator + Sized { /// For sparse implementations, returns `Complex64::new(0.0, 0.0)` for /// basis states not present in the state vector. fn get_amplitude(&mut self, basis_state: usize) -> Complex64; - - /// Get the number of qubits in the simulator. - fn num_qubits(&self) -> usize; } /// Generates a Clifford-only test suite for a state vector simulator. @@ -834,6 +831,33 @@ pub fn verify_pz(sim: &mut S) { // After pz, qubit should be in |0⟩ let result = sim.mz(&qid(0)); assert!(!result[0].outcome, "pz should prepare |0⟩"); + + // PZ on |1⟩: must not produce NaN (regression test for + // projection-based mpz override that divided by sqrt(1-prob_one) + // where prob_one=1.0) + sim.reset(); + sim.x(&qid(0)); // deterministic |1⟩ + sim.pz(&qid(0)); + let amp0 = sim.get_amplitude(0); + assert!( + !amp0.re.is_nan() && !amp0.im.is_nan(), + "pz on |1⟩ must not produce NaN amplitudes" + ); + assert!( + (amp0.norm() - 1.0).abs() < TOLERANCE, + "After pz on |1⟩, qubit should be in |0⟩ with unit amplitude" + ); + let result = sim.mz(&qid(0)); + assert!(!result[0].outcome, "pz on |1⟩ should prepare |0⟩"); + + // PZ on |0⟩: trivial case, should remain |0⟩ + sim.reset(); + sim.pz(&qid(0)); + let amp0 = sim.get_amplitude(0); + assert!( + (amp0.norm() - 1.0).abs() < TOLERANCE, + "pz on |0⟩ should remain |0⟩" + ); } /// Verify pnz (prepare |1⟩) operation. @@ -880,6 +904,37 @@ pub fn verify_pz_multiple_qubits(sim: &mut S) { assert!(result1[0].outcome, "qubit 1 should still be |1⟩"); } +/// Verify mid-circuit reset pattern: H-CX-MZ-PZ-CX-MZ on a Bell pair. +/// +/// This is the pattern used in QEC syndrome extraction with ancilla resets. +/// The bug it catches: if mpz projects onto |0⟩ without proper measurement +/// sampling + conditional X, subsequent gates after PZ produce wrong results. +pub fn verify_mid_circuit_reset(sim: &mut S) { + if sim.num_qubits() < 2 { + return; + } + + // Run many seeds. After H-CX: Bell state (|00⟩+|11⟩)/sqrt(2). + // MZ(1) collapses to |00⟩ or |11⟩. + // PZ(1) resets q1 to |0⟩: state is |00⟩ or |10⟩. + // CX(0,1) re-entangles: |00⟩->|00⟩ or |10⟩->|11⟩. + // MZ(1): should always equal first measurement. + for seed in 0..100 { + let mut s = S::with_seed(2, seed); + s.h(&qid(0)); + s.cx(&qid2(0, 1)); + let r1 = s.mz(&qid(1)); + s.pz(&qid(1)); + s.cx(&qid2(0, 1)); + let r2 = s.mz(&qid(1)); + assert_eq!( + r1[0].outcome, r2[0].outcome, + "seed {seed}: mid-circuit reset: r1={}, r2={} — should match", + r1[0].outcome as u8, r2[0].outcome as u8 + ); + } +} + /// Verify measurement consistency - measuring the same qubit multiple times. pub fn verify_measurement_consistency(sim: &mut S) { // After a measurement, repeated measurements should give the same result @@ -2630,6 +2685,7 @@ pub fn run_measurement_test_suite(sim: &mut S) { verify_pz(sim); verify_pnz(sim); verify_pz_multiple_qubits(sim); + verify_mid_circuit_reset(sim); verify_measurement_consistency(sim); verify_mz_detailed(sim); } @@ -2656,10 +2712,6 @@ impl StateVectorSimulator for StateVecAoS { fn get_amplitude(&mut self, basis_state: usize) -> Complex64 { self.state()[basis_state] } - - fn num_qubits(&self) -> usize { - StateVecAoS::num_qubits(self) - } } impl StateVectorSimulator for StateVecSoA { @@ -2672,10 +2724,6 @@ impl StateVectorSimulator for StateVecSoA { fn get_amplitude(&mut self, basis_state: usize) -> Complex64 { StateVecSoA::get_amplitude(self, basis_state) } - - fn num_qubits(&self) -> usize { - StateVecSoA::num_qubits(self) - } } impl StateVectorSimulator for SparseStateVecAoS { @@ -2686,10 +2734,6 @@ impl StateVectorSimulator for SparseStateVecAoS { fn get_amplitude(&mut self, basis_state: usize) -> Complex64 { SparseStateVecAoS::get_amplitude(self, basis_state) } - - fn num_qubits(&self) -> usize { - SparseStateVecAoS::num_qubits(self) - } } impl StateVectorSimulator for SparseStateVecSoA { @@ -2700,10 +2744,6 @@ impl StateVectorSimulator for SparseStateVecSoA { fn get_amplitude(&mut self, basis_state: usize) -> Complex64 { SparseStateVecSoA::get_amplitude(self, basis_state) } - - fn num_qubits(&self) -> usize { - SparseStateVecSoA::num_qubits(self) - } } // --- Module Tests --- diff --git a/crates/pecos-simulators/src/symbolic_sparse_stab.rs b/crates/pecos-simulators/src/symbolic_sparse_stab.rs index cd573b075..b76028ecc 100644 --- a/crates/pecos-simulators/src/symbolic_sparse_stab.rs +++ b/crates/pecos-simulators/src/symbolic_sparse_stab.rs @@ -26,9 +26,9 @@ //! - `measurement_indices`: Set of measurement indices whose outcomes XOR together //! - `flip`: Boolean indicating whether to flip the result (from unitary gate phases) -use crate::QuantumSimulator; use crate::sign_algebra::{SignAlgebra, SymbolicSign}; use crate::symbolic_gens::SymbolicGensVecSet; +use crate::QuantumSimulator; use core::mem; use pecos_core::{BitSet, Set, VecSet}; @@ -591,6 +591,139 @@ impl SymbolicSparseStabVecSet { .collect() } + /// Prepare qubit in |0⟩ (reset). Does not record a measurement. + /// + /// Physically: measure Z, discard the outcome, conditionally apply X + /// to force the +1 eigenvalue. + /// + /// Symbolically: project qubit onto +Z eigenstate with empty sign + /// (no measurement dependencies). If the qubit is already in a Z + /// eigenstate, H rotates it to the X basis first so the non-deterministic + /// projection path can properly disentangle it from all other qubits. + pub fn pz(&mut self, q: usize) -> &mut Self { + if self.stabs.col_x[q].is_empty() { + // Qubit is in a Z eigenstate. Rotate to X basis so the + // non-deterministic projection correctly disentangles it + // and transfers sign information through the stabilizer group. + self.h(&[q]); + } + self.pz_nondeterministic(q); + self + } + + /// Project qubit onto +Z eigenstate without recording a measurement. + /// + /// Same Gaussian elimination as `nondeterministic_meas` but does not + /// record a measurement or increment the counter. The resulting Z_q + /// stabilizer gets an empty sign (eigenvalue +1). + fn pz_nondeterministic(&mut self, q: usize) { + let mut anticom_stabs_col = self.stabs.col_x[q].clone(); + let mut anticom_destabs_col = self.destabs.col_x[q].clone(); + + // Find stabilizer to replace (smallest weight) + let mut smallest_wt = 2 * self.num_qubits + 2; + let mut removed_id: Option = None; + + for stab_id in &anticom_stabs_col { + let weight = self.stabs.row_x[*stab_id].len() + self.stabs.row_z[*stab_id].len(); + if weight < smallest_wt { + smallest_wt = weight; + removed_id = Some(*stab_id); + } + } + + let id = removed_id.expect("col_x[q] was non-empty"); + anticom_stabs_col.remove(&id); + let removed_row_x = self.stabs.row_x[id].clone(); + let removed_row_z = self.stabs.row_z[id].clone(); + + // Phase tracking for anticommuting stabilizers + if self.stabs.signs_minus.contains(&id) { + self.stabs.signs_minus ^= &anticom_stabs_col; + } + if self.stabs.signs_i.contains(&id) { + self.stabs.signs_i.remove(&id); + let gens_common: Vec<_> = self + .stabs + .signs_i + .intersection(&anticom_stabs_col) + .copied() + .collect(); + let gens_only_stabs: Vec<_> = anticom_stabs_col + .difference(&self.stabs.signs_i) + .copied() + .collect(); + for i in gens_common { + self.stabs.signs_minus ^= &i; + self.stabs.signs_i.remove(&i); + } + for i in gens_only_stabs { + self.stabs.signs_i.insert(i); + } + } + + // Multiply all other anticommuting stabilizers by the removed one + let removed_sign = self.stabs.signs[id].clone(); + for g in &anticom_stabs_col { + self.stabs.signs[*g].multiply_assign(&removed_sign); + let num_minuses = removed_row_z.intersection(&self.stabs.row_x[*g]).count(); + if num_minuses & 1 != 0 { + self.stabs.signs_minus ^= g; + } + self.stabs.row_x[*g] ^= &removed_row_x; + self.stabs.row_z[*g] ^= &removed_row_z; + } + + // Update column storage for stabilizers + for i in &removed_row_x { + self.stabs.col_x[*i] ^= &anticom_stabs_col; + } + for i in &removed_row_z { + self.stabs.col_z[*i] ^= &anticom_stabs_col; + } + + // Remove old stabilizer + for i in &self.stabs.row_x[id] { + self.stabs.col_x[*i].remove(&id); + } + for i in &self.stabs.row_z[id] { + self.stabs.col_z[*i].remove(&id); + } + + // Replace with Z_q, sign = empty (forced +1 eigenvalue) + self.stabs.col_z[q].insert(id); + self.stabs.row_x[id].clear(); + self.stabs.row_z[id].clear(); + self.stabs.row_z[id].insert(q); + self.stabs.signs[id] = SymbolicSign::empty(); + self.stabs.signs_minus.remove(&id); + self.stabs.signs_i.remove(&id); + + // Update destabilizers + for i in &self.destabs.row_x[id] { + self.destabs.col_x[*i].remove(&id); + } + for i in &self.destabs.row_z[id] { + self.destabs.col_z[*i].remove(&id); + } + + anticom_destabs_col.remove(&id); + for i in &removed_row_x { + self.destabs.col_x[*i].insert(id); + self.destabs.col_x[*i] ^= &anticom_destabs_col; + } + for i in &removed_row_z { + self.destabs.col_z[*i].insert(id); + self.destabs.col_z[*i] ^= &anticom_destabs_col; + } + for row in &anticom_destabs_col { + self.destabs.row_x[*row] ^= &removed_row_x; + self.destabs.row_z[*row] ^= &removed_row_z; + } + self.destabs.row_x[id] = removed_row_x; + self.destabs.row_z[id] = removed_row_z; + } + /// Handle a deterministic measurement. /// The outcome is determined by combining: /// 1. XOR of measurement dependencies from contributing stabilizers @@ -790,6 +923,10 @@ impl SymbolicSparseStabVecSet { } impl QuantumSimulator for SymbolicSparseStabVecSet { + fn num_qubits(&self) -> usize { + self.num_qubits + } + #[inline] fn reset(&mut self) -> &mut Self { Self::reset(self) @@ -1279,4 +1416,90 @@ mod tests { assert_eq!(history.format_deterministic(), "[m0=1, m1=0]"); assert_eq!(history.format_nondeterministic(), "[]"); } + + /// Two-round X-stabilizer check: m1 must depend on m0 across reset. + #[test] + fn test_pz_two_round_x_check() { + use crate::measurement_sampler::MeasurementKind; + let mut sim = SymbolicSparseStabVecSet::new(3); + + // Round 1: measure X₁X₂ via ancilla q0 + sim.h(&[0]).cx(&[(0, 1)]).cx(&[(0, 2)]).h(&[0]); + let r0 = sim.mz(&[0]); + assert!(!r0[0].is_deterministic, "m0 should be non-det"); + + sim.pz(0); + + // Round 2: same stabilizer + sim.h(&[0]).cx(&[(0, 1)]).cx(&[(0, 2)]).h(&[0]); + let r1 = sim.mz(&[0]); + + assert!(r1[0].is_deterministic, "m1 should be det, got: {}", r1[0]); + assert_eq!(format!("{}", r1[0]), "m1=m0"); + + let kinds = MeasurementKind::from_history(sim.measurement_history()); + assert!(matches!(kinds[0], MeasurementKind::Random)); + assert!(matches!(kinds[1], MeasurementKind::Copy(0))); + } + + /// Multi-round X-check: correlations must survive 6 reset cycles. + #[test] + fn test_pz_six_round_x_check() { + use crate::measurement_sampler::MeasurementKind; + let mut sim = SymbolicSparseStabVecSet::new(3); + + for _ in 0..6 { + sim.h(&[0]).cx(&[(0, 1)]).cx(&[(0, 2)]).h(&[0]); + sim.mz(&[0]); + sim.pz(0); + } + + let kinds = MeasurementKind::from_history(sim.measurement_history()); + assert_eq!(kinds.len(), 6); + assert!( + matches!(kinds[0], MeasurementKind::Random), + "m0: {:?}", + kinds[0] + ); + // All subsequent measurements must depend on a prior measurement + for (i, k) in kinds.iter().enumerate().skip(1) { + assert!( + matches!(k, MeasurementKind::Copy(_)), + "m{i} should be Copy, got {k:?}" + ); + } + } + + /// After PZ, the reset qubit itself must be fresh (deterministic |0⟩). + #[test] + fn test_pz_reset_qubit_is_fresh() { + let mut sim = SymbolicSparseStabVecSet::new(2); + + // Entangle q0 and q1 via Bell state + sim.h(&[0]).cx(&[(0, 1)]); + // Measure q0 (non-det) + let r = sim.mz(&[0]); + assert!(!r[0].is_deterministic); + + // Reset q0 + sim.pz(0); + + // Measuring q0 again must give deterministic 0 (fresh |0⟩) + let r2 = sim.mz(&[0]); + assert!(r2[0].is_deterministic, "reset qubit should be det"); + assert_eq!(format!("{}", r2[0]), "m1=0", "reset qubit should measure 0"); + } + + /// PZ on a qubit that was never entangled should be a no-op. + #[test] + fn test_pz_on_fresh_qubit() { + let mut sim = SymbolicSparseStabVecSet::new(2); + + // PZ on |0⟩ should not change anything + sim.pz(0); + + let r = sim.mz(&[0]); + assert!(r[0].is_deterministic); + assert_eq!(format!("{}", r[0]), "m0=0"); + } } diff --git a/crates/pecos-simulators/src/symbolic_sparse_stab_bitset.rs b/crates/pecos-simulators/src/symbolic_sparse_stab_bitset.rs index 9e42cf8c8..9ec1a8f4e 100644 --- a/crates/pecos-simulators/src/symbolic_sparse_stab_bitset.rs +++ b/crates/pecos-simulators/src/symbolic_sparse_stab_bitset.rs @@ -51,6 +51,81 @@ pub struct SymbolicSparseStab { measurement_history: MeasurementHistory, } +fn xor_intersection_into(a: &BitSet, b: &BitSet, target: &mut BitSet) { + for i in a { + if b.contains(i) { + target.toggle(i); + } + } +} + +fn mul_i_for(signs_minus: &mut BitSet, signs_i: &mut BitSet, indices: &BitSet) { + for i in indices { + if signs_i.contains(i) { + signs_minus.toggle(i); + signs_i.remove(i); + } else { + signs_i.insert(i); + } + } +} + +fn mul_minus_i_for(signs_minus: &mut BitSet, signs_i: &mut BitSet, indices: &BitSet) { + *signs_minus ^= indices; + mul_i_for(signs_minus, signs_i, indices); +} + +fn toggle_col_x(gens: &mut SymbolicGensBitSet, q: usize, affected: &BitSet) { + let old = gens.col_x[q].clone(); + gens.col_x[q] ^= affected; + for i in &old { + if !gens.col_x[q].contains(i) { + gens.row_x[i].remove(q); + } + } + for i in &gens.col_x[q] { + if !old.contains(i) { + gens.row_x[i].insert(q); + } + } +} + +fn toggle_col_z(gens: &mut SymbolicGensBitSet, q: usize, affected: &BitSet) { + let old = gens.col_z[q].clone(); + gens.col_z[q] ^= affected; + for i in &old { + if !gens.col_z[q].contains(i) { + gens.row_z[i].remove(q); + } + } + for i in &gens.col_z[q] { + if !old.contains(i) { + gens.row_z[i].insert(q); + } + } +} + +fn swap_xz_on(gens: &mut SymbolicGensBitSet, q: usize) { + let only_x: Vec = gens.col_x[q] + .iter() + .filter(|i| !gens.col_z[q].contains(*i)) + .collect(); + let only_z: Vec = gens.col_z[q] + .iter() + .filter(|i| !gens.col_x[q].contains(*i)) + .collect(); + + for i in only_x { + gens.row_x[i].remove(q); + gens.row_z[i].insert(q); + } + for i in only_z { + gens.row_z[i].remove(q); + gens.row_x[i].insert(q); + } + mem::swap(&mut gens.col_x[q], &mut gens.col_z[q]); +} + impl SymbolicSparseStab { /// Create a new BitSet-based symbolic stabilizer simulator. #[inline] @@ -238,6 +313,99 @@ impl SymbolicSparseStab { self } + /// Adjoint sqrt of Z gate. X -> -Y, Z -> Z. + #[inline] + pub fn szdg(&mut self, qubits: &[usize]) -> &mut Self { + for &q in qubits { + let affected = self.stabs.col_x[q].clone(); + mul_minus_i_for( + &mut self.stabs.signs_minus, + &mut self.stabs.signs_i, + &affected, + ); + + for gens in [&mut self.stabs, &mut self.destabs] { + let affected = gens.col_x[q].clone(); + toggle_col_z(gens, q, &affected); + } + } + self + } + + /// Sqrt of X gate. X -> X, Z -> -Y. + #[inline] + pub fn sx(&mut self, qubits: &[usize]) -> &mut Self { + for &q in qubits { + let affected = self.stabs.col_z[q].clone(); + mul_minus_i_for( + &mut self.stabs.signs_minus, + &mut self.stabs.signs_i, + &affected, + ); + + for gens in [&mut self.stabs, &mut self.destabs] { + let affected = gens.col_z[q].clone(); + toggle_col_x(gens, q, &affected); + } + } + self + } + + /// Adjoint sqrt of X gate. X -> X, Z -> Y. + #[inline] + pub fn sxdg(&mut self, qubits: &[usize]) -> &mut Self { + for &q in qubits { + let affected = self.stabs.col_z[q].clone(); + mul_i_for( + &mut self.stabs.signs_minus, + &mut self.stabs.signs_i, + &affected, + ); + + for gens in [&mut self.stabs, &mut self.destabs] { + let affected = gens.col_z[q].clone(); + toggle_col_x(gens, q, &affected); + } + } + self + } + + /// Sqrt of Y gate. X -> -Z, Z -> X. + #[inline] + pub fn sy(&mut self, qubits: &[usize]) -> &mut Self { + for &q in qubits { + self.stabs.signs_minus ^= &self.stabs.col_x[q]; + xor_intersection_into( + &self.stabs.col_x[q], + &self.stabs.col_z[q], + &mut self.stabs.signs_minus, + ); + + for gens in [&mut self.stabs, &mut self.destabs] { + swap_xz_on(gens, q); + } + } + self + } + + /// Adjoint sqrt of Y gate. X -> Z, Z -> -X. + #[inline] + pub fn sydg(&mut self, qubits: &[usize]) -> &mut Self { + for &q in qubits { + self.stabs.signs_minus ^= &self.stabs.col_z[q]; + xor_intersection_into( + &self.stabs.col_x[q], + &self.stabs.col_z[q], + &mut self.stabs.signs_minus, + ); + + for gens in [&mut self.stabs, &mut self.destabs] { + swap_xz_on(gens, q); + } + } + self + } + /// CNOT gate. IX -> IX, XI -> XX, IZ -> ZZ, ZI -> ZI #[inline] pub fn cx(&mut self, pairs: &[(usize, usize)]) -> &mut Self { @@ -288,6 +456,256 @@ impl SymbolicSparseStab { self } + /// Controlled-Y gate. XI -> XY, IX -> ZX, ZI -> ZI, IZ -> ZZ. + #[inline] + pub fn cy(&mut self, pairs: &[(usize, usize)]) -> &mut Self { + for &(q1, q2) in pairs { + // Direct Pauli action, including the target-Y phase for XI. + let affected = self.stabs.col_x[q1].clone(); + let mut both_x = BitSet::new(); + for g in &self.stabs.col_x[q1] { + if self.stabs.col_x[q2].contains(g) { + both_x.insert(g); + } + } + self.stabs.signs_minus ^= &both_x; + mul_i_for( + &mut self.stabs.signs_minus, + &mut self.stabs.signs_i, + &affected, + ); + + for gens in [&mut self.stabs, &mut self.destabs] { + let x1 = gens.col_x[q1].clone(); + let x2 = gens.col_x[q2].clone(); + let z2 = gens.col_z[q2].clone(); + toggle_col_x(gens, q2, &x1); + toggle_col_z(gens, q2, &x1); + + let mut z1_effect = x2; + z1_effect ^= &z2; + toggle_col_z(gens, q1, &z1_effect); + } + } + self + } + + /// Controlled-Z gate. XI -> XZ, IX -> ZX, ZI -> ZI, IZ -> IZ. + #[inline] + pub fn cz(&mut self, pairs: &[(usize, usize)]) -> &mut Self { + for &(q1, q2) in pairs { + xor_intersection_into( + &self.stabs.col_x[q1], + &self.stabs.col_x[q2], + &mut self.stabs.signs_minus, + ); + + for gens in [&mut self.stabs, &mut self.destabs] { + let x1 = gens.col_x[q1].clone(); + let x2 = gens.col_x[q2].clone(); + toggle_col_z(gens, q2, &x1); + toggle_col_z(gens, q1, &x2); + } + } + self + } + + /// Square root of XX gate. XI -> XI, IX -> IX, ZI -> -YX, IZ -> -XY. + #[inline] + pub fn sxx(&mut self, pairs: &[(usize, usize)]) -> &mut Self { + for &(q1, q2) in pairs { + let mut affected = self.stabs.col_z[q1].clone(); + affected ^= &self.stabs.col_z[q2]; + mul_minus_i_for( + &mut self.stabs.signs_minus, + &mut self.stabs.signs_i, + &affected, + ); + + for gens in [&mut self.stabs, &mut self.destabs] { + let mut affected = gens.col_z[q1].clone(); + affected ^= &gens.col_z[q2]; + toggle_col_x(gens, q1, &affected); + toggle_col_x(gens, q2, &affected); + } + } + self + } + + /// Adjoint square root of XX gate. XI -> XI, IX -> IX, ZI -> YX, IZ -> XY. + #[inline] + pub fn sxxdg(&mut self, pairs: &[(usize, usize)]) -> &mut Self { + for &(q1, q2) in pairs { + let mut affected = self.stabs.col_z[q1].clone(); + affected ^= &self.stabs.col_z[q2]; + mul_i_for( + &mut self.stabs.signs_minus, + &mut self.stabs.signs_i, + &affected, + ); + + for gens in [&mut self.stabs, &mut self.destabs] { + let mut affected = gens.col_z[q1].clone(); + affected ^= &gens.col_z[q2]; + toggle_col_x(gens, q1, &affected); + toggle_col_x(gens, q2, &affected); + } + } + self + } + + /// Square root of ZZ gate. XI -> YZ, IX -> ZY, ZI -> ZI, IZ -> IZ. + #[inline] + pub fn szz(&mut self, pairs: &[(usize, usize)]) -> &mut Self { + for &(q1, q2) in pairs { + let mut affected = self.stabs.col_x[q1].clone(); + affected ^= &self.stabs.col_x[q2]; + mul_i_for( + &mut self.stabs.signs_minus, + &mut self.stabs.signs_i, + &affected, + ); + + for gens in [&mut self.stabs, &mut self.destabs] { + let mut affected = gens.col_x[q1].clone(); + affected ^= &gens.col_x[q2]; + toggle_col_z(gens, q1, &affected); + toggle_col_z(gens, q2, &affected); + } + } + self + } + + /// Adjoint square root of ZZ gate. XI -> -YZ, IX -> -ZY, ZI -> ZI, IZ -> IZ. + #[inline] + pub fn szzdg(&mut self, pairs: &[(usize, usize)]) -> &mut Self { + for &(q1, q2) in pairs { + let mut affected = self.stabs.col_x[q1].clone(); + affected ^= &self.stabs.col_x[q2]; + mul_minus_i_for( + &mut self.stabs.signs_minus, + &mut self.stabs.signs_i, + &affected, + ); + + for gens in [&mut self.stabs, &mut self.destabs] { + let mut affected = gens.col_x[q1].clone(); + affected ^= &gens.col_x[q2]; + toggle_col_z(gens, q1, &affected); + toggle_col_z(gens, q2, &affected); + } + } + self + } + + /// Square root of YY gate. + /// + /// XI -> -ZY, IX -> -YZ, ZI -> XY, IZ -> YX. + #[inline] + pub fn syy(&mut self, pairs: &[(usize, usize)]) -> &mut Self { + for &(q1, q2) in pairs { + self.apply_syy_signs(q1, q2, false); + self.apply_syy_bits(q1, q2); + } + self + } + + /// Adjoint square root of YY gate. + /// + /// XI -> ZY, IX -> YZ, ZI -> -XY, IZ -> -YX. + #[inline] + pub fn syydg(&mut self, pairs: &[(usize, usize)]) -> &mut Self { + for &(q1, q2) in pairs { + self.apply_syy_signs(q1, q2, true); + self.apply_syy_bits(q1, q2); + } + self + } + + /// SWAP gate. XI -> IX, IX -> XI, ZI -> IZ, IZ -> ZI. + #[inline] + pub fn swap(&mut self, pairs: &[(usize, usize)]) -> &mut Self { + for &(q1, q2) in pairs { + for gens in [&mut self.stabs, &mut self.destabs] { + let mut affected_x = gens.col_x[q1].clone(); + affected_x ^= &gens.col_x[q2]; + toggle_col_x(gens, q1, &affected_x); + toggle_col_x(gens, q2, &affected_x); + + let mut affected_z = gens.col_z[q1].clone(); + affected_z ^= &gens.col_z[q2]; + toggle_col_z(gens, q1, &affected_z); + toggle_col_z(gens, q2, &affected_z); + } + } + self + } + + fn apply_syy_bits(&mut self, q1: usize, q2: usize) { + for gens in [&mut self.stabs, &mut self.destabs] { + let mut affected = gens.col_x[q1].clone(); + affected ^= &gens.col_z[q1]; + affected ^= &gens.col_x[q2]; + affected ^= &gens.col_z[q2]; + toggle_col_x(gens, q1, &affected); + toggle_col_x(gens, q2, &affected); + toggle_col_z(gens, q1, &affected); + toggle_col_z(gens, q2, &affected); + } + } + + fn apply_syy_signs(&mut self, q1: usize, q2: usize, adjoint: bool) { + let col_x = &self.stabs.col_x; + let col_z = &self.stabs.col_z; + let signs_minus = &mut self.stabs.signs_minus; + let signs_i = &mut self.stabs.signs_i; + + macro_rules! apply_syy_sign { + ($g:expr, $x1:expr, $z1:expr, $x2:expr, $z2:expr) => { + if ($x1 != $z1) != ($x2 != $z2) { + let use_plus_i = ($z1 != $z2) != adjoint; + if use_plus_i { + mul_i_for(signs_minus, signs_i, &BitSet::single($g)); + } else { + mul_minus_i_for(signs_minus, signs_i, &BitSet::single($g)); + } + } + }; + } + + for g in &col_x[q1] { + let x1 = true; + let z1 = col_z[q1].contains(g); + let x2 = col_x[q2].contains(g); + let z2 = col_z[q2].contains(g); + apply_syy_sign!(g, x1, z1, x2, z2); + } + for g in &col_z[q1] { + if col_x[q1].contains(g) { + continue; + } + let x1 = false; + let z1 = true; + let x2 = col_x[q2].contains(g); + let z2 = col_z[q2].contains(g); + apply_syy_sign!(g, x1, z1, x2, z2); + } + for g in &col_x[q2] { + if col_x[q1].contains(g) || col_z[q1].contains(g) { + continue; + } + let x2 = true; + let z2 = col_z[q2].contains(g); + apply_syy_sign!(g, false, false, x2, z2); + } + for g in &col_z[q2] { + if col_x[q1].contains(g) || col_z[q1].contains(g) || col_x[q2].contains(g) { + continue; + } + apply_syy_sign!(g, false, false, false, true); + } + } + // ==================== Measurement ==================== /// Measure qubits in the Z basis. @@ -308,6 +726,129 @@ impl SymbolicSparseStab { .collect() } + /// Prepare qubit in |0⟩ (reset). Does not record a measurement. + /// + /// See `SymbolicSparseStabVecSet::pz` for detailed documentation. + pub fn pz(&mut self, q: usize) -> &mut Self { + if self.stabs.col_x[q].is_empty() { + self.h(&[q]); + } + self.pz_nondeterministic(q); + self + } + + /// Project qubit onto +Z eigenstate without recording a measurement. + /// + /// Same Gaussian elimination as `nondeterministic_meas` but with + /// empty sign and no measurement counter increment. + fn pz_nondeterministic(&mut self, q: usize) { + let mut anticom_stabs_col = self.stabs.col_x[q].clone(); + let mut anticom_destabs_col = self.destabs.col_x[q].clone(); + + let mut smallest_wt = 2 * self.num_qubits + 2; + let mut removed_id: Option = None; + + for stab_id in &anticom_stabs_col { + let weight = self.stabs.row_x[stab_id].len() + self.stabs.row_z[stab_id].len(); + if weight < smallest_wt { + smallest_wt = weight; + removed_id = Some(stab_id); + } + } + + let id = removed_id.expect("col_x[q] was non-empty"); + anticom_stabs_col.remove(id); + let removed_row_x = self.stabs.row_x[id].clone(); + let removed_row_z = self.stabs.row_z[id].clone(); + + if self.stabs.signs_minus.contains(id) { + self.stabs.signs_minus ^= &anticom_stabs_col; + } + if self.stabs.signs_i.contains(id) { + self.stabs.signs_i.remove(id); + let gens_common: Vec = self + .stabs + .signs_i + .iter() + .filter(|i| anticom_stabs_col.contains(*i)) + .collect(); + let gens_only_stabs: Vec = anticom_stabs_col + .iter() + .filter(|i| !self.stabs.signs_i.contains(*i)) + .collect(); + for i in gens_common { + let i_set = BitSet::single(i); + self.stabs.signs_minus ^= &i_set; + self.stabs.signs_i.remove(i); + } + for i in gens_only_stabs { + self.stabs.signs_i.insert(i); + } + } + + let removed_sign = self.stabs.signs[id].clone(); + for g in &anticom_stabs_col { + self.stabs.signs[g].multiply_assign(&removed_sign); + let mut num_minuses = 0; + for z in &removed_row_z { + if self.stabs.row_x[g].contains(z) { + num_minuses += 1; + } + } + if num_minuses & 1 != 0 { + let g_set = BitSet::single(g); + self.stabs.signs_minus ^= &g_set; + } + self.stabs.row_x[g] ^= &removed_row_x; + self.stabs.row_z[g] ^= &removed_row_z; + } + + for i in &removed_row_x { + self.stabs.col_x[i] ^= &anticom_stabs_col; + } + for i in &removed_row_z { + self.stabs.col_z[i] ^= &anticom_stabs_col; + } + + for i in &self.stabs.row_x[id] { + self.stabs.col_x[i].remove(id); + } + for i in &self.stabs.row_z[id] { + self.stabs.col_z[i].remove(id); + } + + self.stabs.col_z[q].insert(id); + self.stabs.row_x[id].clear(); + self.stabs.row_z[id].clear(); + self.stabs.row_z[id].insert(q); + self.stabs.signs[id] = SymbolicSign::empty(); + self.stabs.signs_minus.remove(id); + self.stabs.signs_i.remove(id); + + for i in &self.destabs.row_x[id] { + self.destabs.col_x[i].remove(id); + } + for i in &self.destabs.row_z[id] { + self.destabs.col_z[i].remove(id); + } + + anticom_destabs_col.remove(id); + for i in &removed_row_x { + self.destabs.col_x[i].insert(id); + self.destabs.col_x[i] ^= &anticom_destabs_col; + } + for i in &removed_row_z { + self.destabs.col_z[i].insert(id); + self.destabs.col_z[i] ^= &anticom_destabs_col; + } + for row in &anticom_destabs_col { + self.destabs.row_x[row] ^= &removed_row_x; + self.destabs.row_z[row] ^= &removed_row_z; + } + self.destabs.row_x[id] = removed_row_x; + self.destabs.row_z[id] = removed_row_z; + } + /// Handle a deterministic measurement. fn deterministic_meas(&mut self, q: usize) -> SymbolicMeasurementResult { let index = self.measurement_counter; @@ -503,6 +1044,10 @@ impl SymbolicSparseStab { } impl QuantumSimulator for SymbolicSparseStab { + fn num_qubits(&self) -> usize { + self.num_qubits + } + #[inline] fn reset(&mut self) -> &mut Self { Self::reset(self) @@ -512,6 +1057,322 @@ impl QuantumSimulator for SymbolicSparseStab { #[cfg(test)] mod tests { use super::*; + use crate::clifford_matrix_oracle::{ + CliffordMatrixGate, SignedPauli, all_pauli_strings, conjugate_pauli, + }; + + fn assert_same_gens(left: &SymbolicGensBitSet, right: &SymbolicGensBitSet) { + assert_eq!(left.col_x, right.col_x); + assert_eq!(left.col_z, right.col_z); + assert_eq!(left.row_x, right.row_x); + assert_eq!(left.row_z, right.row_z); + assert_eq!(left.signs, right.signs); + assert_eq!(left.signs_minus, right.signs_minus); + assert_eq!(left.signs_i, right.signs_i); + } + + fn assert_same_state(left: &SymbolicSparseStab, right: &SymbolicSparseStab) { + assert_same_gens(&left.stabs, &right.stabs); + assert_same_gens(&left.destabs, &right.destabs); + assert_eq!(left.measurement_counter, right.measurement_counter); + assert_eq!( + left.measurement_history.as_slice(), + right.measurement_history.as_slice() + ); + } + + fn nontrivial_state() -> SymbolicSparseStab { + let mut sim = SymbolicSparseStab::new(3); + sim.h(&[0, 1]); + sim.cx(&[(0, 2), (1, 2)]); + sim.sz(&[0, 2]); + sim.h(&[2]); + sim + } + + fn check_direct_gate( + apply_direct: impl FnOnce(&mut SymbolicSparseStab), + apply_reference: impl FnOnce(&mut SymbolicSparseStab), + ) { + let mut direct = nontrivial_state(); + let mut reference = direct.clone(); + apply_direct(&mut direct); + apply_reference(&mut reference); + assert_same_state(&direct, &reference); + } + + fn row_binary(gens: &SymbolicGensBitSet, row: usize, num_qubits: usize) -> String { + let mut dense = String::with_capacity(num_qubits); + for q in 0..num_qubits { + dense.push( + match (gens.row_x[row].contains(q), gens.row_z[row].contains(q)) { + (false, false) => 'I', + (true, false) => 'X', + (false, true) => 'Z', + (true, true) => 'Y', + }, + ); + } + dense + } + + fn assert_symbolic_single_qubit_gate_basis( + apply: impl FnOnce(&mut SymbolicSparseStab), + expected_x: &str, + expected_z: &str, + ) { + let mut sim = SymbolicSparseStab::new(1); + apply(&mut sim); + + assert_eq!(row_binary(&sim.destabs, 0, 1), expected_x, "X image"); + assert_eq!(row_binary(&sim.stabs, 0, 1), expected_z, "Z image"); + } + + fn assert_symbolic_two_qubit_gate_basis( + apply: impl FnOnce(&mut SymbolicSparseStab), + expected_xi: &str, + expected_ix: &str, + expected_zi: &str, + expected_iz: &str, + ) { + let mut sim = SymbolicSparseStab::new(2); + apply(&mut sim); + + assert_eq!(row_binary(&sim.destabs, 0, 2), expected_xi, "XI image"); + assert_eq!(row_binary(&sim.destabs, 1, 2), expected_ix, "IX image"); + assert_eq!(row_binary(&sim.stabs, 0, 2), expected_zi, "ZI image"); + assert_eq!(row_binary(&sim.stabs, 1, 2), expected_iz, "IZ image"); + } + + fn set_stab_row_to_pauli(gens: &mut SymbolicGensBitSet, row: usize, pauli: &str) { + let mut y_count = 0usize; + for (q, label) in pauli.chars().enumerate() { + match label { + 'I' => {} + 'X' => { + gens.row_x[row].insert(q); + gens.col_x[q].insert(row); + } + 'Y' => { + y_count += 1; + gens.row_x[row].insert(q); + gens.row_z[row].insert(q); + gens.col_x[q].insert(row); + gens.col_z[q].insert(row); + } + 'Z' => { + gens.row_z[row].insert(q); + gens.col_z[q].insert(row); + } + _ => panic!("invalid Pauli label {label}"), + } + } + + match y_count % 4 { + 0 => {} + 1 => { + gens.signs_i.insert(row); + } + 2 => { + gens.signs_minus.insert(row); + } + 3 => { + gens.signs_minus.insert(row); + gens.signs_i.insert(row); + } + _ => unreachable!(), + } + } + + fn signed_stab_row(gens: &SymbolicGensBitSet, row: usize, num_qubits: usize) -> SignedPauli { + assert!( + gens.signs[row].measurements.is_empty(), + "unexpected measurement-dependent sign" + ); + let pauli = row_binary(gens, row, num_qubits); + let y_count = pauli.chars().filter(|&label| label == 'Y').count(); + let internal_phase = usize::from(gens.signs_i.contains(row)) + + if gens.signs_minus.contains(row) { 2 } else { 0 }; + let canonical_phase = (internal_phase + 3 * y_count) % 4; + assert!( + canonical_phase == 0 || canonical_phase == 2, + "unexpected non-Hermitian phase i^{canonical_phase} for row {row}" + ); + SignedPauli { + sign: if canonical_phase == 2 { -1 } else { 1 }, + pauli, + } + } + + fn symbolic_image_for_pauli(num_qubits: usize, input: &str, apply: F) -> SignedPauli + where + F: FnOnce(&mut SymbolicSparseStab), + { + let mut sim = SymbolicSparseStab::new(num_qubits); + sim.stabs = SymbolicGensBitSet::new(num_qubits); + sim.destabs = SymbolicGensBitSet::new(num_qubits); + set_stab_row_to_pauli(&mut sim.stabs, 0, input); + apply(&mut sim); + signed_stab_row(&sim.stabs, 0, num_qubits) + } + + fn assert_symbolic_gate_matches_matrix_oracle( + name: &str, + gate: CliffordMatrixGate, + num_qubits: usize, + apply: F, + ) where + F: Fn(&mut SymbolicSparseStab) + Copy, + { + for input in all_pauli_strings(num_qubits) { + let expected = conjugate_pauli(gate, &input); + let observed = symbolic_image_for_pauli(num_qubits, &input, apply); + assert_eq!(observed, expected, "{name}: {input}"); + } + } + + fn reverse_two_qubit_pauli(pauli: &str) -> String { + let labels: Vec = pauli.chars().collect(); + assert_eq!(labels.len(), 2); + [labels[1], labels[0]].into_iter().collect() + } + + fn assert_symbolic_reversed_pair_matches_matrix_oracle( + name: &str, + gate: CliffordMatrixGate, + apply: F, + ) where + F: Fn(&mut SymbolicSparseStab, &[(usize, usize)]) + Copy, + { + for input in all_pauli_strings(2) { + let oracle_input = reverse_two_qubit_pauli(&input); + let mut expected = conjugate_pauli(gate, &oracle_input); + expected.pauli = reverse_two_qubit_pauli(&expected.pauli); + + let observed = symbolic_image_for_pauli(2, &input, |sim| { + apply(sim, &[(1, 0)]); + }); + assert_eq!(observed, expected, "{name} reversed pair: {input}"); + } + } + + fn assert_symbolic_two_pair_batch_matches_sequential(name: &str, apply: F) + where + F: Fn(&mut SymbolicSparseStab, &[(usize, usize)]) + Copy, + { + for input in all_pauli_strings(4) { + let batched = symbolic_image_for_pauli(4, &input, |sim| { + apply(sim, &[(0, 1), (2, 3)]); + }); + let sequential = symbolic_image_for_pauli(4, &input, |sim| { + apply(sim, &[(0, 1)]); + apply(sim, &[(2, 3)]); + }); + assert_eq!(batched, sequential, "{name} batched: {input}"); + } + } + + fn ref_szdg(sim: &mut SymbolicSparseStab, qs: &[usize]) { + sim.z(qs); + sim.sz(qs); + } + + fn ref_sx(sim: &mut SymbolicSparseStab, qs: &[usize]) { + sim.h(qs); + sim.sz(qs); + sim.h(qs); + } + + fn ref_sxdg(sim: &mut SymbolicSparseStab, qs: &[usize]) { + sim.h(qs); + ref_szdg(sim, qs); + sim.h(qs); + } + + fn ref_sy(sim: &mut SymbolicSparseStab, qs: &[usize]) { + sim.z(qs); + sim.h(qs); + } + + fn ref_sydg(sim: &mut SymbolicSparseStab, qs: &[usize]) { + sim.h(qs); + sim.z(qs); + } + + fn ref_cy(sim: &mut SymbolicSparseStab, pairs: &[(usize, usize)]) { + let targets: Vec = pairs.iter().map(|&(_, q2)| q2).collect(); + ref_szdg(sim, &targets); + sim.cx(pairs); + sim.sz(&targets); + } + + fn ref_cz(sim: &mut SymbolicSparseStab, pairs: &[(usize, usize)]) { + let targets: Vec = pairs.iter().map(|&(_, q2)| q2).collect(); + sim.h(&targets); + sim.cx(pairs); + sim.h(&targets); + } + + fn ref_sxx(sim: &mut SymbolicSparseStab, pairs: &[(usize, usize)]) { + let q1s: Vec = pairs.iter().map(|&(q1, _)| q1).collect(); + let q2s: Vec = pairs.iter().map(|&(_, q2)| q2).collect(); + ref_sx(sim, &q1s); + ref_sx(sim, &q2s); + ref_sydg(sim, &q1s); + sim.cx(pairs); + ref_sy(sim, &q1s); + } + + fn ref_sxxdg(sim: &mut SymbolicSparseStab, pairs: &[(usize, usize)]) { + let q1s: Vec = pairs.iter().map(|&(q1, _)| q1).collect(); + let q2s: Vec = pairs.iter().map(|&(_, q2)| q2).collect(); + sim.x(&q1s); + sim.x(&q2s); + ref_sxx(sim, pairs); + } + + fn ref_syy(sim: &mut SymbolicSparseStab, pairs: &[(usize, usize)]) { + let q1s: Vec = pairs.iter().map(|&(q1, _)| q1).collect(); + let q2s: Vec = pairs.iter().map(|&(_, q2)| q2).collect(); + ref_szdg(sim, &q1s); + ref_szdg(sim, &q2s); + ref_sxx(sim, pairs); + sim.sz(&q1s); + sim.sz(&q2s); + } + + fn ref_syydg(sim: &mut SymbolicSparseStab, pairs: &[(usize, usize)]) { + let q1s: Vec = pairs.iter().map(|&(q1, _)| q1).collect(); + let q2s: Vec = pairs.iter().map(|&(_, q2)| q2).collect(); + sim.y(&q1s); + sim.y(&q2s); + ref_syy(sim, pairs); + } + + fn ref_szz(sim: &mut SymbolicSparseStab, pairs: &[(usize, usize)]) { + let q1s: Vec = pairs.iter().map(|&(q1, _)| q1).collect(); + let q2s: Vec = pairs.iter().map(|&(_, q2)| q2).collect(); + sim.h(&q1s); + sim.h(&q2s); + ref_sxx(sim, pairs); + sim.h(&q1s); + sim.h(&q2s); + } + + fn ref_szzdg(sim: &mut SymbolicSparseStab, pairs: &[(usize, usize)]) { + let q1s: Vec = pairs.iter().map(|&(q1, _)| q1).collect(); + let q2s: Vec = pairs.iter().map(|&(_, q2)| q2).collect(); + sim.z(&q1s); + sim.z(&q2s); + ref_szz(sim, pairs); + } + + fn ref_swap(sim: &mut SymbolicSparseStab, pairs: &[(usize, usize)]) { + let reversed: Vec<(usize, usize)> = pairs.iter().map(|&(q1, q2)| (q2, q1)).collect(); + sim.cx(pairs); + sim.cx(&reversed); + sim.cx(pairs); + } #[test] fn test_bell_state_bitset() { @@ -548,4 +1409,390 @@ mod tests { assert!(r1.outcome.is_empty()); assert_eq!(r1.index, 1); } + + #[test] + fn test_direct_clifford_gate_binary_truth_tables() { + assert_symbolic_single_qubit_gate_basis( + |sim| { + sim.szdg(&[0]); + }, + "Y", + "Z", + ); + assert_symbolic_single_qubit_gate_basis( + |sim| { + sim.sx(&[0]); + }, + "X", + "Y", + ); + assert_symbolic_single_qubit_gate_basis( + |sim| { + sim.sxdg(&[0]); + }, + "X", + "Y", + ); + assert_symbolic_single_qubit_gate_basis( + |sim| { + sim.sy(&[0]); + }, + "Z", + "X", + ); + assert_symbolic_single_qubit_gate_basis( + |sim| { + sim.sydg(&[0]); + }, + "Z", + "X", + ); + assert_symbolic_two_qubit_gate_basis( + |sim| { + sim.cy(&[(0, 1)]); + }, + "XY", + "ZX", + "ZI", + "ZZ", + ); + assert_symbolic_two_qubit_gate_basis( + |sim| { + sim.cz(&[(0, 1)]); + }, + "XZ", + "ZX", + "ZI", + "IZ", + ); + assert_symbolic_two_qubit_gate_basis( + |sim| { + sim.sxx(&[(0, 1)]); + }, + "XI", + "IX", + "YX", + "XY", + ); + assert_symbolic_two_qubit_gate_basis( + |sim| { + sim.sxxdg(&[(0, 1)]); + }, + "XI", + "IX", + "YX", + "XY", + ); + assert_symbolic_two_qubit_gate_basis( + |sim| { + sim.syy(&[(0, 1)]); + }, + "ZY", + "YZ", + "XY", + "YX", + ); + assert_symbolic_two_qubit_gate_basis( + |sim| { + sim.syydg(&[(0, 1)]); + }, + "ZY", + "YZ", + "XY", + "YX", + ); + assert_symbolic_two_qubit_gate_basis( + |sim| { + sim.szz(&[(0, 1)]); + }, + "YZ", + "ZY", + "ZI", + "IZ", + ); + assert_symbolic_two_qubit_gate_basis( + |sim| { + sim.szzdg(&[(0, 1)]); + }, + "YZ", + "ZY", + "ZI", + "IZ", + ); + assert_symbolic_two_qubit_gate_basis( + |sim| { + sim.swap(&[(0, 1)]); + }, + "IX", + "XI", + "IZ", + "ZI", + ); + } + + #[test] + fn test_direct_clifford_gates_match_matrix_oracle_for_all_paulis() { + assert_symbolic_gate_matches_matrix_oracle("CX", CliffordMatrixGate::CX, 2, |sim| { + sim.cx(&[(0, 1)]); + }); + assert_symbolic_gate_matches_matrix_oracle("SZdg", CliffordMatrixGate::SZdg, 1, |sim| { + sim.szdg(&[0]); + }); + assert_symbolic_gate_matches_matrix_oracle("F", CliffordMatrixGate::F, 1, |sim| { + sim.sx(&[0]); + sim.sz(&[0]); + }); + assert_symbolic_gate_matches_matrix_oracle("Fdg", CliffordMatrixGate::Fdg, 1, |sim| { + sim.szdg(&[0]); + sim.sxdg(&[0]); + }); + assert_symbolic_gate_matches_matrix_oracle("SX", CliffordMatrixGate::SX, 1, |sim| { + sim.sx(&[0]); + }); + assert_symbolic_gate_matches_matrix_oracle("SXdg", CliffordMatrixGate::SXdg, 1, |sim| { + sim.sxdg(&[0]); + }); + assert_symbolic_gate_matches_matrix_oracle("SY", CliffordMatrixGate::SY, 1, |sim| { + sim.sy(&[0]); + }); + assert_symbolic_gate_matches_matrix_oracle("SYdg", CliffordMatrixGate::SYdg, 1, |sim| { + sim.sydg(&[0]); + }); + assert_symbolic_gate_matches_matrix_oracle("CY", CliffordMatrixGate::CY, 2, |sim| { + sim.cy(&[(0, 1)]); + }); + assert_symbolic_gate_matches_matrix_oracle("CZ", CliffordMatrixGate::CZ, 2, |sim| { + sim.cz(&[(0, 1)]); + }); + assert_symbolic_gate_matches_matrix_oracle("SXX", CliffordMatrixGate::SXX, 2, |sim| { + sim.sxx(&[(0, 1)]); + }); + assert_symbolic_gate_matches_matrix_oracle("SXXdg", CliffordMatrixGate::SXXdg, 2, |sim| { + sim.sxxdg(&[(0, 1)]); + }); + assert_symbolic_gate_matches_matrix_oracle("SYY", CliffordMatrixGate::SYY, 2, |sim| { + sim.syy(&[(0, 1)]); + }); + assert_symbolic_gate_matches_matrix_oracle("SYYdg", CliffordMatrixGate::SYYdg, 2, |sim| { + sim.syydg(&[(0, 1)]); + }); + assert_symbolic_gate_matches_matrix_oracle("SZZ", CliffordMatrixGate::SZZ, 2, |sim| { + sim.szz(&[(0, 1)]); + }); + assert_symbolic_gate_matches_matrix_oracle("SZZdg", CliffordMatrixGate::SZZdg, 2, |sim| { + sim.szzdg(&[(0, 1)]); + }); + assert_symbolic_gate_matches_matrix_oracle("SWAP", CliffordMatrixGate::SWAP, 2, |sim| { + sim.swap(&[(0, 1)]); + }); + } + + #[test] + fn test_cy_xx_sign_regression() { + assert_eq!( + symbolic_image_for_pauli(2, "XX", |sim| { + sim.cy(&[(0, 1)]); + }), + SignedPauli { + sign: -1, + pauli: "YZ".to_string() + } + ); + } + + #[test] + fn test_two_qubit_gates_reversed_pair_matches_matrix_oracle() { + assert_symbolic_reversed_pair_matches_matrix_oracle( + "CX", + CliffordMatrixGate::CX, + |sim, pairs| { + sim.cx(pairs); + }, + ); + assert_symbolic_reversed_pair_matches_matrix_oracle( + "CY", + CliffordMatrixGate::CY, + |sim, pairs| { + sim.cy(pairs); + }, + ); + assert_symbolic_reversed_pair_matches_matrix_oracle( + "CZ", + CliffordMatrixGate::CZ, + |sim, pairs| { + sim.cz(pairs); + }, + ); + assert_symbolic_reversed_pair_matches_matrix_oracle( + "SXX", + CliffordMatrixGate::SXX, + |sim, pairs| { + sim.sxx(pairs); + }, + ); + assert_symbolic_reversed_pair_matches_matrix_oracle( + "SXXdg", + CliffordMatrixGate::SXXdg, + |sim, pairs| { + sim.sxxdg(pairs); + }, + ); + assert_symbolic_reversed_pair_matches_matrix_oracle( + "SYY", + CliffordMatrixGate::SYY, + |sim, pairs| { + sim.syy(pairs); + }, + ); + assert_symbolic_reversed_pair_matches_matrix_oracle( + "SYYdg", + CliffordMatrixGate::SYYdg, + |sim, pairs| { + sim.syydg(pairs); + }, + ); + assert_symbolic_reversed_pair_matches_matrix_oracle( + "SZZ", + CliffordMatrixGate::SZZ, + |sim, pairs| { + sim.szz(pairs); + }, + ); + assert_symbolic_reversed_pair_matches_matrix_oracle( + "SZZdg", + CliffordMatrixGate::SZZdg, + |sim, pairs| { + sim.szzdg(pairs); + }, + ); + assert_symbolic_reversed_pair_matches_matrix_oracle( + "SWAP", + CliffordMatrixGate::SWAP, + |sim, pairs| { + sim.swap(pairs); + }, + ); + } + + #[test] + fn test_two_qubit_gate_batches_match_sequential_pairs() { + assert_symbolic_two_pair_batch_matches_sequential("CX", |sim, pairs| { + sim.cx(pairs); + }); + assert_symbolic_two_pair_batch_matches_sequential("CY", |sim, pairs| { + sim.cy(pairs); + }); + assert_symbolic_two_pair_batch_matches_sequential("CZ", |sim, pairs| { + sim.cz(pairs); + }); + assert_symbolic_two_pair_batch_matches_sequential("SXX", |sim, pairs| { + sim.sxx(pairs); + }); + assert_symbolic_two_pair_batch_matches_sequential("SXXdg", |sim, pairs| { + sim.sxxdg(pairs); + }); + assert_symbolic_two_pair_batch_matches_sequential("SYY", |sim, pairs| { + sim.syy(pairs); + }); + assert_symbolic_two_pair_batch_matches_sequential("SYYdg", |sim, pairs| { + sim.syydg(pairs); + }); + assert_symbolic_two_pair_batch_matches_sequential("SZZ", |sim, pairs| { + sim.szz(pairs); + }); + assert_symbolic_two_pair_batch_matches_sequential("SZZdg", |sim, pairs| { + sim.szzdg(pairs); + }); + assert_symbolic_two_pair_batch_matches_sequential("SWAP", |sim, pairs| { + sim.swap(pairs); + }); + } + + #[test] + fn test_direct_clifford_gates_match_reference_sequences() { + check_direct_gate( + |sim| { + sim.szdg(&[0]); + }, + |sim| ref_szdg(sim, &[0]), + ); + check_direct_gate( + |sim| { + sim.sx(&[0]); + }, + |sim| ref_sx(sim, &[0]), + ); + check_direct_gate( + |sim| { + sim.sxdg(&[0]); + }, + |sim| ref_sxdg(sim, &[0]), + ); + check_direct_gate( + |sim| { + sim.sy(&[0]); + }, + |sim| ref_sy(sim, &[0]), + ); + check_direct_gate( + |sim| { + sim.sydg(&[0]); + }, + |sim| ref_sydg(sim, &[0]), + ); + check_direct_gate( + |sim| { + sim.cy(&[(0, 1)]); + }, + |sim| ref_cy(sim, &[(0, 1)]), + ); + check_direct_gate( + |sim| { + sim.cz(&[(0, 1)]); + }, + |sim| ref_cz(sim, &[(0, 1)]), + ); + check_direct_gate( + |sim| { + sim.sxx(&[(0, 1)]); + }, + |sim| ref_sxx(sim, &[(0, 1)]), + ); + check_direct_gate( + |sim| { + sim.sxxdg(&[(0, 1)]); + }, + |sim| ref_sxxdg(sim, &[(0, 1)]), + ); + check_direct_gate( + |sim| { + sim.syy(&[(0, 1)]); + }, + |sim| ref_syy(sim, &[(0, 1)]), + ); + check_direct_gate( + |sim| { + sim.syydg(&[(0, 1)]); + }, + |sim| ref_syydg(sim, &[(0, 1)]), + ); + check_direct_gate( + |sim| { + sim.szz(&[(0, 1)]); + }, + |sim| ref_szz(sim, &[(0, 1)]), + ); + check_direct_gate( + |sim| { + sim.szzdg(&[(0, 1)]); + }, + |sim| ref_szzdg(sim, &[(0, 1)]), + ); + check_direct_gate( + |sim| { + sim.swap(&[(0, 1)]); + }, + |sim| ref_swap(sim, &[(0, 1)]), + ); + } } diff --git a/crates/pecos-simulators/tests/measurement_stress_tests.rs b/crates/pecos-simulators/tests/measurement_stress_tests.rs new file mode 100644 index 000000000..f31a295dd --- /dev/null +++ b/crates/pecos-simulators/tests/measurement_stress_tests.rs @@ -0,0 +1,43 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Measurement stress tests for all rotation-capable simulators. + +use pecos_simulators::{ + DensityMatrix, SparseStateVecAoS, SparseStateVecSoA, StabVec, StateVecAoS, StateVecSoA, + StateVecSoA32, +}; + +// State vector simulators +pecos_simulators::measurement_stress_test_suite!(StateVecSoA, 4, StateVecSoA::with_seed(4, 42)); +pecos_simulators::measurement_stress_test_suite!(StateVecSoA32, 4, StateVecSoA32::with_seed(4, 42)); +pecos_simulators::measurement_stress_test_suite!(StateVecAoS, 4, StateVecAoS::with_seed(4, 42)); +pecos_simulators::measurement_stress_test_suite!( + SparseStateVecAoS, + 4, + SparseStateVecAoS::with_seed(4, 42) +); +pecos_simulators::measurement_stress_test_suite!( + SparseStateVecSoA, + 4, + SparseStateVecSoA::with_seed(4, 42) +); + +// Density matrix +pecos_simulators::measurement_stress_test_suite!(DensityMatrix, 4, DensityMatrix::with_seed(4, 42)); + +// Clifford+Rz (exact mode) +pecos_simulators::measurement_stress_test_suite!( + StabVec, + 4, + StabVec::builder(4).seed(42).pruning_threshold(0.0).build() +); diff --git a/crates/pecos-tesseract/build_tesseract.rs b/crates/pecos-tesseract/build_tesseract.rs index 1c10e3166..a9f7f3966 100644 --- a/crates/pecos-tesseract/build_tesseract.rs +++ b/crates/pecos-tesseract/build_tesseract.rs @@ -52,18 +52,19 @@ pub fn build() -> Result<()> { println!("cargo:rustc-link-search=native={}", out_dir.display()); println!("cargo:rustc-link-lib=static=tesseract-bridge"); - // Get Tesseract and Stim sources (downloads to ~/.pecos/cache/, extracts to ~/.pecos/deps/) + // Get Tesseract, Stim, and Boost sources (downloads to ~/.pecos/cache/, extracts to ~/.pecos/deps/) let manifest = Manifest::find_and_load_validated()?; let tesseract_dir = ensure_dep_ready("tesseract", &manifest)?; let stim_dir = ensure_dep_ready("stim", &manifest)?; + let boost_dir = ensure_dep_ready("boost", &manifest)?; // Build using cxx - build_cxx_bridge(&tesseract_dir, &stim_dir); + build_cxx_bridge(&tesseract_dir, &stim_dir, &boost_dir); Ok(()) } -fn build_cxx_bridge(tesseract_dir: &Path, stim_dir: &Path) { +fn build_cxx_bridge(tesseract_dir: &Path, stim_dir: &Path, boost_dir: &Path) { let tesseract_src_dir = tesseract_dir.join("src"); let stim_src_dir = stim_dir.join("src"); @@ -87,6 +88,7 @@ fn build_cxx_bridge(tesseract_dir: &Path, stim_dir: &Path) { build .file(tesseract_src_dir.join("common.cc")) .file(tesseract_src_dir.join("utils.cc")) + .file(tesseract_src_dir.join("visualization.cc")) .file(tesseract_src_dir.join("tesseract.cc")); // Configure build @@ -94,6 +96,7 @@ fn build_cxx_bridge(tesseract_dir: &Path, stim_dir: &Path) { .std("c++20") .include(&tesseract_src_dir) .include(&stim_src_dir) + .include(boost_dir) .include("include") .include("src") .define("TESSERACT_BRIDGE_EXPORTS", None); diff --git a/crates/pecos-tesseract/examples/tesseract_usage.rs b/crates/pecos-tesseract/examples/tesseract_usage.rs index 7500fc0bb..40b6814c0 100644 --- a/crates/pecos-tesseract/examples/tesseract_usage.rs +++ b/crates/pecos-tesseract/examples/tesseract_usage.rs @@ -131,7 +131,6 @@ error(0.0005) D1 D3 L0 det_beam: 50, beam_climbing: true, no_revisit_dets: false, - at_most_two_errors_per_detector: true, verbose: false, pqlimit: 10000, det_penalty: 0.05, @@ -161,10 +160,6 @@ error(0.0005) D1 D3 L0 " No revisit detectors: {}", custom_decoder.no_revisit_dets() ); - println!( - " At most two errors per detector: {}", - custom_decoder.at_most_two_errors_per_detector() - ); println!(" Priority queue limit: {}", custom_decoder.pqlimit()); println!(" Detector penalty: {:.3}", custom_decoder.det_penalty()); diff --git a/crates/pecos-tesseract/include/tesseract_bridge.h b/crates/pecos-tesseract/include/tesseract_bridge.h index 75ea89fea..d87177c86 100644 --- a/crates/pecos-tesseract/include/tesseract_bridge.h +++ b/crates/pecos-tesseract/include/tesseract_bridge.h @@ -30,7 +30,6 @@ class TesseractDecoderWrapper { uint16_t get_det_beam() const; bool get_beam_climbing() const; bool get_no_revisit_dets() const; - bool get_at_most_two_errors_per_detector() const; bool get_verbose() const; size_t get_pqlimit() const; double get_det_penalty() const; @@ -74,7 +73,6 @@ size_t get_num_observables(const TesseractDecoderWrapper& decoder); uint16_t get_det_beam(const TesseractDecoderWrapper& decoder); bool get_beam_climbing(const TesseractDecoderWrapper& decoder); bool get_no_revisit_dets(const TesseractDecoderWrapper& decoder); -bool get_at_most_two_errors_per_detector(const TesseractDecoderWrapper& decoder); bool get_verbose(const TesseractDecoderWrapper& decoder); size_t get_pqlimit(const TesseractDecoderWrapper& decoder); double get_det_penalty(const TesseractDecoderWrapper& decoder); diff --git a/crates/pecos-tesseract/pecos.toml b/crates/pecos-tesseract/pecos.toml index 7d0dab5e3..4e7316ed3 100644 --- a/crates/pecos-tesseract/pecos.toml +++ b/crates/pecos-tesseract/pecos.toml @@ -4,13 +4,19 @@ version = 1 [dependencies.stim] -version = "bd60b73525fd5a9b30839020eb7554ad369e4337" -url = "https://github.com/quantumlib/Stim/archive/bd60b73525fd5a9b30839020eb7554ad369e4337.tar.gz" -sha256 = "2a4be24295ce3018d79e08369b31e401a2d33cd8b3a75675d57dac3afd9de37d" +version = "213275795e49027772bea7c610b6aac3a80583e1" +url = "https://github.com/quantumlib/Stim/archive/213275795e49027772bea7c610b6aac3a80583e1.tar.gz" +sha256 = "b63c4ae94494a8819d440757776cf80a829ec1e30454fa7c9b0f670e981938ab" description = "Stabilizer simulator for QEC" +[dependencies.boost] +version = "1.83.0" +url = "https://archives.boost.io/release/1.83.0/source/boost_1_83_0.tar.bz2" +sha256 = "6478edfe2f3305127cffe8caf73ea0176c53769f4bf1585be237eb30798c3b8e" +description = "C++ Boost libraries" + [dependencies.tesseract] -version = "1d81f0b385b6a9de49ae361d08bd6b5dbcec1773" -url = "https://github.com/quantumlib/tesseract-decoder/archive/1d81f0b385b6a9de49ae361d08bd6b5dbcec1773.tar.gz" -sha256 = "0b5d8bfa63bab68ab4882510a96d7e238d598d2ba0e669a8903af142ce276892" +version = "56dd8d5fee3834ef85ca9475a10e708f7d245bea" +url = "https://github.com/quantumlib/tesseract-decoder/archive/56dd8d5fee3834ef85ca9475a10e708f7d245bea.tar.gz" +sha256 = "8736ec264fb9a6310957470ac3c63a6d1ce2a26002821caeb64ad91148893e9e" description = "Tesseract decoder" diff --git a/crates/pecos-tesseract/src/bridge.cpp b/crates/pecos-tesseract/src/bridge.cpp index 65260dedb..9366bfa63 100644 --- a/crates/pecos-tesseract/src/bridge.cpp +++ b/crates/pecos-tesseract/src/bridge.cpp @@ -5,7 +5,9 @@ #include #include #include -#include // Required for std::iota on MSVC +#include // Required for std::iota on MSVC +#include // std::mt19937, std::shuffle +#include // std::shuffle // Include Tesseract headers #include "tesseract.h" @@ -40,28 +42,21 @@ class TesseractDecoderWrapper::Impl { INF_DET_BEAM : static_cast(config_repr.det_beam); config.beam_climbing = config_repr.beam_climbing; config.no_revisit_dets = config_repr.no_revisit_dets; - config.at_most_two_errors_per_detector = config_repr.at_most_two_errors_per_detector; config.verbose = config_repr.verbose; + config.merge_errors = true; config.pqlimit = config_repr.pqlimit; config.det_penalty = config_repr.det_penalty; - // Initialize detector orders with a default ordering - if (config.det_orders.empty()) { - std::vector default_order; - size_t num_dets = config.dem.count_detectors(); - for (size_t i = 0; i < num_dets; ++i) { - default_order.push_back(i); - } - config.det_orders.push_back(default_order); - } + // Generate BFS-based detector orderings (upstream default). + // BFS on the detector graph produces spatially-aware orderings + // that help the A* search find short paths faster. + config.det_orders = build_det_orders(config.dem, 20, DetOrder::DetBFS, 2384753); config_ = config; decoder_ = std::make_unique(std::move(config)); } DecodingResultRepr decode_detections(const rust::Slice detections) { - // Use data()+size() instead of begin()/end() iterators to avoid - // Xcode 15.4 libc++ pointer_traits incompatibility with cxx iterators in C++20 std::vector det_vec(detections.data(), detections.data() + detections.size()); decoder_->decode_to_errors(det_vec); @@ -72,7 +67,8 @@ class TesseractDecoderWrapper::Impl { result.predicted_errors.push_back(err); } - result.observables_mask = decoder_->mask_from_errors(decoder_->predicted_errors_buffer); + result.observables_mask = vector_to_u64_mask( + decoder_->get_flipped_observables(decoder_->predicted_errors_buffer)); result.cost = decoder_->cost_from_errors(decoder_->predicted_errors_buffer); result.low_confidence = decoder_->low_confidence_flag; @@ -85,7 +81,7 @@ class TesseractDecoderWrapper::Impl { ) { std::vector det_vec(detections.data(), detections.data() + detections.size()); - decoder_->decode_to_errors(det_vec, det_order); + decoder_->decode_to_errors(det_vec, det_order, config_.det_beam); DecodingResultRepr result; result.predicted_errors = rust::Vec(); @@ -93,7 +89,8 @@ class TesseractDecoderWrapper::Impl { result.predicted_errors.push_back(err); } - result.observables_mask = decoder_->mask_from_errors(decoder_->predicted_errors_buffer); + result.observables_mask = vector_to_u64_mask( + decoder_->get_flipped_observables(decoder_->predicted_errors_buffer)); result.cost = decoder_->cost_from_errors(decoder_->predicted_errors_buffer); result.low_confidence = decoder_->low_confidence_flag; @@ -125,10 +122,6 @@ class TesseractDecoderWrapper::Impl { return config_.no_revisit_dets; } - bool get_at_most_two_errors_per_detector() const { - return config_.at_most_two_errors_per_detector; - } - bool get_verbose() const { return config_.verbose; } @@ -145,7 +138,7 @@ class TesseractDecoderWrapper::Impl { if (error_idx >= decoder_->errors.size()) { throw std::out_of_range("Error index out of range"); } - return decoder_->errors[error_idx].probability; + return decoder_->errors[error_idx].get_probability(); } double get_error_cost(size_t error_idx) const { @@ -171,31 +164,17 @@ class TesseractDecoderWrapper::Impl { if (error_idx >= decoder_->errors.size()) { throw std::out_of_range("Error index out of range"); } - return decoder_->errors[error_idx].symptom.observables; + return vector_to_u64_mask(decoder_->errors[error_idx].symptom.observables); } uint64_t mask_from_errors(const rust::Slice error_indices) const { - // Work around Tesseract bug: functions ignore parameter and use internal buffer - // So we calculate the mask ourselves - uint64_t mask = 0; - for (size_t ei : error_indices) { - if (ei < decoder_->errors.size()) { - mask ^= decoder_->errors[ei].symptom.observables; - } - } - return mask; + std::vector indices(error_indices.data(), error_indices.data() + error_indices.size()); + return vector_to_u64_mask(decoder_->get_flipped_observables(indices)); } double cost_from_errors(const rust::Slice error_indices) const { - // Work around Tesseract bug: functions ignore parameter and use internal buffer - // So we calculate the cost ourselves - double total_cost = 0; - for (size_t ei : error_indices) { - if (ei < decoder_->errors.size()) { - total_cost += decoder_->errors[ei].likelihood_cost; - } - } - return total_cost; + std::vector indices(error_indices.data(), error_indices.data() + error_indices.size()); + return decoder_->cost_from_errors(indices); } }; @@ -245,9 +224,6 @@ bool TesseractDecoderWrapper::get_no_revisit_dets() const { return pimpl_->get_no_revisit_dets(); } -bool TesseractDecoderWrapper::get_at_most_two_errors_per_detector() const { - return pimpl_->get_at_most_two_errors_per_detector(); -} bool TesseractDecoderWrapper::get_verbose() const { return pimpl_->get_verbose(); @@ -345,10 +321,6 @@ bool get_no_revisit_dets(const TesseractDecoderWrapper& decoder) { return decoder.get_no_revisit_dets(); } -bool get_at_most_two_errors_per_detector(const TesseractDecoderWrapper& decoder) { - return decoder.get_at_most_two_errors_per_detector(); -} - bool get_verbose(const TesseractDecoderWrapper& decoder) { return decoder.get_verbose(); } diff --git a/crates/pecos-tesseract/src/bridge.rs b/crates/pecos-tesseract/src/bridge.rs index f22e68d26..f73a72528 100644 --- a/crates/pecos-tesseract/src/bridge.rs +++ b/crates/pecos-tesseract/src/bridge.rs @@ -11,7 +11,6 @@ pub(crate) mod ffi { pub det_beam: u16, pub beam_climbing: bool, pub no_revisit_dets: bool, - pub at_most_two_errors_per_detector: bool, pub verbose: bool, pub pqlimit: usize, pub det_penalty: f64, @@ -80,9 +79,6 @@ pub(crate) mod ffi { /// Check if detector revisiting is disabled. fn get_no_revisit_dets(decoder: &TesseractDecoderWrapper) -> bool; - /// Check if at-most-two-errors-per-detector is enabled. - fn get_at_most_two_errors_per_detector(decoder: &TesseractDecoderWrapper) -> bool; - /// Check if verbose mode is enabled. fn get_verbose(decoder: &TesseractDecoderWrapper) -> bool; diff --git a/crates/pecos-tesseract/src/decoder.rs b/crates/pecos-tesseract/src/decoder.rs index a58068d28..4962d2163 100644 --- a/crates/pecos-tesseract/src/decoder.rs +++ b/crates/pecos-tesseract/src/decoder.rs @@ -45,8 +45,6 @@ pub struct TesseractConfig { pub beam_climbing: bool, /// Avoid revisiting detectors during search pub no_revisit_dets: bool, - /// Limit to at most two errors per detector - pub at_most_two_errors_per_detector: bool, /// Enable verbose output pub verbose: bool, /// Priority queue size limit @@ -60,10 +58,9 @@ impl Default for TesseractConfig { Self { det_beam: u16::MAX, // Infinite beam by default beam_climbing: false, - no_revisit_dets: false, - at_most_two_errors_per_detector: false, + no_revisit_dets: true, verbose: false, - pqlimit: usize::MAX, + pqlimit: 200_000, det_penalty: 0.0, } } @@ -74,12 +71,11 @@ impl TesseractConfig { #[must_use] pub fn fast() -> Self { Self { - det_beam: 100, + det_beam: 5, beam_climbing: true, no_revisit_dets: true, - at_most_two_errors_per_detector: true, verbose: false, - pqlimit: 1_000_000, + pqlimit: 200_000, det_penalty: 0.1, } } @@ -91,9 +87,8 @@ impl TesseractConfig { det_beam: u16::MAX, beam_climbing: false, no_revisit_dets: false, - at_most_two_errors_per_detector: false, verbose: false, - pqlimit: usize::MAX, + pqlimit: 1_000_000, det_penalty: 0.0, } } @@ -105,7 +100,6 @@ impl TesseractConfig { det_beam: self.det_beam, beam_climbing: self.beam_climbing, no_revisit_dets: self.no_revisit_dets, - at_most_two_errors_per_detector: self.at_most_two_errors_per_detector, verbose: self.verbose, pqlimit: self.pqlimit, det_penalty: self.det_penalty, @@ -336,12 +330,6 @@ impl TesseractDecoder { ffi::get_no_revisit_dets(&self.inner) } - /// Check if at-most-two-errors-per-detector is enabled - #[must_use] - pub fn at_most_two_errors_per_detector(&self) -> bool { - ffi::get_at_most_two_errors_per_detector(&self.inner) - } - /// Check if verbose mode is enabled #[must_use] pub fn verbose(&self) -> bool { @@ -361,6 +349,24 @@ impl TesseractDecoder { } } +impl pecos_decoder_core::ObservableDecoder for TesseractDecoder { + fn decode_to_observables( + &mut self, + syndrome: &[u8], + ) -> Result { + let detections: Vec = syndrome + .iter() + .enumerate() + .filter_map(|(i, &val)| if val != 0 { Some(i as u64) } else { None }) + .collect(); + let det_arr = Array1::from_vec(detections); + let result = self + .decode_detections(&det_arr.view()) + .map_err(|e| pecos_decoder_core::DecoderError::DecodingFailed(e.to_string()))?; + Ok(result.observables_mask) + } +} + impl Decoder for TesseractDecoder { type Result = DecodingResult; type Error = TesseractError; @@ -416,10 +422,9 @@ mod tests { #[test] fn test_tesseract_config_fast() { let config = TesseractConfig::fast(); - assert_eq!(config.det_beam, 100); + assert_eq!(config.det_beam, 5); assert!(config.beam_climbing); assert!(config.no_revisit_dets); - assert!(config.at_most_two_errors_per_detector); } #[test] @@ -428,6 +433,5 @@ mod tests { assert_eq!(config.det_beam, u16::MAX); assert!(!config.beam_climbing); assert!(!config.no_revisit_dets); - assert!(!config.at_most_two_errors_per_detector); } } diff --git a/crates/pecos-tesseract/tests/tesseract/tesseract_comprehensive_tests.rs b/crates/pecos-tesseract/tests/tesseract/tesseract_comprehensive_tests.rs index 6ef83e46a..27c49d542 100644 --- a/crates/pecos-tesseract/tests/tesseract/tesseract_comprehensive_tests.rs +++ b/crates/pecos-tesseract/tests/tesseract/tesseract_comprehensive_tests.rs @@ -166,7 +166,7 @@ error(0.1) D2 D3 // Test fast configuration let fast_config = TesseractConfig::fast(); let mut fast_decoder = TesseractDecoder::new(dem, fast_config).unwrap(); - assert_eq!(fast_decoder.det_beam(), 100); + assert_eq!(fast_decoder.det_beam(), 5); assert!(fast_decoder.beam_climbing()); // Test accurate configuration @@ -250,10 +250,9 @@ fn test_configuration_getters() { let dem = "error(0.1) D0"; let custom_config = TesseractConfig { - det_beam: 50, + det_beam: 5, beam_climbing: true, no_revisit_dets: false, - at_most_two_errors_per_detector: true, verbose: false, pqlimit: 5000, det_penalty: 0.05, @@ -262,10 +261,9 @@ fn test_configuration_getters() { let decoder = TesseractDecoder::new(dem, custom_config).unwrap(); // Verify all configuration values - assert_eq!(decoder.det_beam(), 50); + assert_eq!(decoder.det_beam(), 5); assert!(decoder.beam_climbing()); assert!(!decoder.no_revisit_dets()); - assert!(decoder.at_most_two_errors_per_detector()); assert!(!decoder.verbose()); assert_eq!(decoder.pqlimit(), 5000); assert!((decoder.det_penalty() - 0.05).abs() < 0.001); diff --git a/crates/pecos-tesseract/tests/tesseract/tesseract_tests.rs b/crates/pecos-tesseract/tests/tesseract/tesseract_tests.rs index bba9578f3..b2b96b62a 100644 --- a/crates/pecos-tesseract/tests/tesseract/tesseract_tests.rs +++ b/crates/pecos-tesseract/tests/tesseract/tesseract_tests.rs @@ -9,10 +9,9 @@ fn test_tesseract_config_default() { let config = TesseractConfig::default(); assert_eq!(config.det_beam, u16::MAX); assert!(!config.beam_climbing); - assert!(!config.no_revisit_dets); - assert!(!config.at_most_two_errors_per_detector); + assert!(config.no_revisit_dets); assert!(!config.verbose); - assert_eq!(config.pqlimit, usize::MAX); + assert_eq!(config.pqlimit, 200_000); assert!( config.det_penalty.abs() < f64::EPSILON, "det_penalty should be 0.0 but was {}", @@ -23,12 +22,11 @@ fn test_tesseract_config_default() { #[test] fn test_tesseract_config_fast() { let config = TesseractConfig::fast(); - assert_eq!(config.det_beam, 100); + assert_eq!(config.det_beam, 5); assert!(config.beam_climbing); assert!(config.no_revisit_dets); - assert!(config.at_most_two_errors_per_detector); assert!(!config.verbose); - assert_eq!(config.pqlimit, 1_000_000); + assert_eq!(config.pqlimit, 200_000); assert!( (config.det_penalty - 0.1).abs() < f64::EPSILON, "det_penalty should be 0.1 but was {}", @@ -42,9 +40,8 @@ fn test_tesseract_config_accurate() { assert_eq!(config.det_beam, u16::MAX); assert!(!config.beam_climbing); assert!(!config.no_revisit_dets); - assert!(!config.at_most_two_errors_per_detector); assert!(!config.verbose); - assert_eq!(config.pqlimit, usize::MAX); + assert_eq!(config.pqlimit, 1_000_000); assert!( config.det_penalty.abs() < f64::EPSILON, "det_penalty should be 0.0 but was {}", @@ -55,20 +52,18 @@ fn test_tesseract_config_accurate() { #[test] fn test_tesseract_config_to_ffi_repr() { let config = TesseractConfig { - det_beam: 50, + det_beam: 5, beam_climbing: true, no_revisit_dets: false, - at_most_two_errors_per_detector: true, verbose: true, pqlimit: 5000, det_penalty: 0.05, }; let ffi_repr = config.to_ffi_repr(); - assert_eq!(ffi_repr.det_beam, 50); + assert_eq!(ffi_repr.det_beam, 5); assert!(ffi_repr.beam_climbing); assert!(!ffi_repr.no_revisit_dets); - assert!(ffi_repr.at_most_two_errors_per_detector); assert!(ffi_repr.verbose); assert_eq!(ffi_repr.pqlimit, 5000); assert!( diff --git a/crates/pecos-uf-decoder/Cargo.toml b/crates/pecos-uf-decoder/Cargo.toml new file mode 100644 index 000000000..27b28a9d4 --- /dev/null +++ b/crates/pecos-uf-decoder/Cargo.toml @@ -0,0 +1,26 @@ +[package] +name = "pecos-uf-decoder" +version.workspace = true +edition.workspace = true +readme = "README.md" +authors.workspace = true +homepage.workspace = true +repository.workspace = true +license.workspace = true +keywords.workspace = true +categories.workspace = true +description = "Fast syndrome-graph Union-Find decoder for PECOS" + +[dependencies] +pecos-decoder-core.workspace = true +pecos-random.workspace = true +rayon.workspace = true + +[lib] +name = "pecos_uf_decoder" + +[dev-dependencies] +fastrand.workspace = true + +[lints] +workspace = true diff --git a/crates/pecos-uf-decoder/examples/profile_decode.rs b/crates/pecos-uf-decoder/examples/profile_decode.rs new file mode 100644 index 000000000..5726a8ff1 --- /dev/null +++ b/crates/pecos-uf-decoder/examples/profile_decode.rs @@ -0,0 +1,150 @@ +// Simple profiling harness for the UF decoder. +// Run with: cargo run --release --example profile_decode -p pecos-uf-decoder + +use pecos_decoder_core::dem::DemMatchingGraph; +use pecos_uf_decoder::{UfDecoder, UfDecoderConfig}; +use std::time::Instant; + +const D3_DEM: &str = + include_str!("../../../examples/surface_code_circuits/surface_code_d3_z_stim.dem"); +const D5_DEM: &str = + include_str!("../../../examples/surface_code_circuits/surface_code_d5_z_stim.dem"); + +fn profile_decoder(name: &str, dem: &str, num_shots: usize) { + let graph = DemMatchingGraph::from_dem_str(dem).unwrap(); + let mut dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::fast()); + let num_det = graph.num_detectors; + + // Generate random syndromes + let mut rng = fastrand::Rng::with_seed(42); + let syndromes: Vec> = (0..num_shots) + .map(|_| { + (0..num_det) + .map(|_| u8::from(rng.f64() < 0.05)) + .collect() + }) + .collect(); + + // Warm up + for syn in &syndromes[..100.min(num_shots)] { + let _ = dec.decode_syndrome(syn); + } + + // Time the full batch + let t0 = Instant::now(); + let mut errors = 0u64; + for syn in &syndromes { + let obs = dec.decode_syndrome(syn); + errors += obs; + } + let elapsed = t0.elapsed(); + + let per_shot_ns = elapsed.as_nanos() as f64 / num_shots as f64; + let throughput = num_shots as f64 / elapsed.as_secs_f64(); + println!( + "{name:8}: {num_det:3} det, {per_shot_ns:8.0} ns/shot ({:.0} kshots/s), errors={errors}", + throughput / 1000.0 + ); +} + +fn profile_phases(name: &str, dem: &str, num_shots: usize) { + let graph = DemMatchingGraph::from_dem_str(dem).unwrap(); + let num_det = graph.num_detectors; + let num_edges = graph.edges.len(); + + let mut rng = fastrand::Rng::with_seed(42); + let syndromes: Vec> = (0..num_shots) + .map(|_| { + (0..num_det) + .map(|_| u8::from(rng.f64() < 0.05)) + .collect() + }) + .collect(); + + // Phase 1: measure reset + syndrome loading only + let mut dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::fast()); + let t0 = Instant::now(); + for syn in &syndromes { + dec.syndrome_validate(syn); // reset + grow (no peel) + } + let grow_time = t0.elapsed(); + + // Phase 2: measure full decode (reset + grow + peel) + let t0 = Instant::now(); + for syn in &syndromes { + let _ = dec.decode_syndrome(syn); + } + let total_time = t0.elapsed(); + + let grow_ns = grow_time.as_nanos() as f64 / num_shots as f64; + let total_ns = total_time.as_nanos() as f64 / num_shots as f64; + let peel_ns = total_ns - grow_ns; + + println!( + "{name}: {num_det} det, {num_edges} edges | total {total_ns:.0} ns = grow {grow_ns:.0} ns ({:.0}%) + peel {peel_ns:.0} ns ({:.0}%)", + grow_ns / total_ns * 100.0, + peel_ns / total_ns * 100.0, + ); + + // Also profile BP+UF if available + if let Ok(mut bp_dec) = + pecos_uf_decoder::BpUfDecoder::from_dem(dem, pecos_uf_decoder::BpUfConfig::default()) + { + use pecos_decoder_core::ObservableDecoder; + let t0 = Instant::now(); + for syn in &syndromes { + let _ = bp_dec.decode_to_observables(syn); + } + let bp_total = t0.elapsed(); + let bp_ns = bp_total.as_nanos() as f64 / num_shots as f64; + let bp_only = bp_ns - total_ns; // approximate BP overhead + println!( + " BP+UF: {bp_ns:.0} ns/shot total (BP overhead ~{bp_only:.0} ns = {:.0}%)", + bp_only / bp_ns * 100.0, + ); + } +} + +const D7_DEM: &str = + include_str!("../../../examples/surface_code_circuits/surface_code_d7_z_stim.dem"); + +fn main() { + let num_shots = 100_000; + + println!("=== UF Decoder Profiling ({num_shots} shots) ==="); + println!(); + + profile_decoder("d3", D3_DEM, num_shots); + profile_decoder("d5", D5_DEM, num_shots); + profile_decoder("d7", D7_DEM, num_shots); + + println!(); + println!("=== Phase breakdown ==="); + profile_phases("d3", D3_DEM, num_shots); + profile_phases("d5", D5_DEM, num_shots); + profile_phases("d7", D7_DEM, num_shots); + + // Also profile with balanced config (Prim MST) + println!(); + println!("=== Balanced (Prim MST) ==="); + let graph = DemMatchingGraph::from_dem_str(D5_DEM).unwrap(); + let mut dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::balanced()); + let num_det = graph.num_detectors; + + let mut rng = fastrand::Rng::with_seed(42); + let syndromes: Vec> = (0..num_shots) + .map(|_| { + (0..num_det) + .map(|_| u8::from(rng.f64() < 0.05)) + .collect() + }) + .collect(); + + let t0 = Instant::now(); + for syn in &syndromes { + let _ = dec.decode_syndrome(syn); + } + let elapsed = t0.elapsed(); + let per_shot_ns = elapsed.as_nanos() as f64 / num_shots as f64; + println!("d5-bal : {num_det:3} det, {per_shot_ns:8.0} ns/shot"); +} diff --git a/crates/pecos-uf-decoder/src/astar.rs b/crates/pecos-uf-decoder/src/astar.rs new file mode 100644 index 000000000..1b0b56bc8 --- /dev/null +++ b/crates/pecos-uf-decoder/src/astar.rs @@ -0,0 +1,501 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! A* error-set decoder inspired by Tesseract (Google, arXiv:2503.10988). +//! +//! Searches over error mechanism subsets to find the minimum-weight +//! error set consistent with the syndrome. Uses `DetCost` heuristic +//! (per-detector minimum mechanism cost) for admissible pruning. +//! +//! Key pruning strategies from Tesseract: +//! - **Canonical expansion**: only expand mechanisms incident to the +//! lowest-index unsatisfied detector +//! - **No-revisit-dets**: skip states with previously-seen residual syndromes +//! - **Beam**: skip states with too many residual defects +//! - **PQ limit**: terminate after a fixed number of expansions +//! +//! Uses u64 bitsets for compact state representation and fast operations. + +use pecos_decoder_core::ObservableDecoder; +use pecos_decoder_core::dem::DemMatchingGraph; +use pecos_decoder_core::errors::DecoderError; +use std::cmp::Reverse; +use std::collections::{BinaryHeap, HashSet}; + +/// A mechanism (error) in the DEM. +struct Mechanism { + detectors: Vec, + obs_mask: u64, + weight: f64, +} + +/// Configuration for the A* decoder. +#[derive(Debug, Clone, Copy)] +pub struct AStarConfig { + /// Maximum priority queue pops before terminating. + pub pq_limit: usize, + /// Beam: skip states with > beam more residual defects than best seen. + pub beam: usize, +} + +impl Default for AStarConfig { + fn default() -> Self { + Self { + pq_limit: 50_000, + beam: 20, + } + } +} + +/// Compact bitset for detector/mechanism membership. +#[derive(Clone, PartialEq, Eq, Hash)] +struct Bitset { + words: Vec, +} + +impl Bitset { + fn new(n: usize) -> Self { + Self { + words: vec![0u64; n.div_ceil(64)], + } + } + + fn get(&self, i: usize) -> bool { + let (word, bit) = (i / 64, i % 64); + word < self.words.len() && (self.words[word] & (1u64 << bit)) != 0 + } + + fn set(&mut self, i: usize) { + let (word, bit) = (i / 64, i % 64); + if word < self.words.len() { + self.words[word] |= 1u64 << bit; + } + } + + fn flip(&mut self, i: usize) { + let (word, bit) = (i / 64, i % 64); + if word < self.words.len() { + self.words[word] ^= 1u64 << bit; + } + } + + fn count_ones(&self) -> usize { + self.words.iter().map(|w| w.count_ones() as usize).sum() + } + + /// Find the index of the lowest set bit, or None. + fn lowest_set(&self) -> Option { + for (wi, &w) in self.words.iter().enumerate() { + if w != 0 { + return Some(wi * 64 + w.trailing_zeros() as usize); + } + } + None + } +} + +/// A* error-set search decoder. +pub struct AStarDecoder { + mechanisms: Vec, + /// Per-detector: list of mechanism indices incident to this detector. + det_to_mechs: Vec>, + num_detectors: usize, + num_mechanisms: usize, + config: AStarConfig, +} + +/// State in the A* search (compact representation). +struct SearchState { + errors: Bitset, + residual: Bitset, + num_residual: usize, + g_cost: f64, + obs_mask: u64, + /// Per-detector: how many included errors are incident to this detector. + det_error_count: Vec, + /// Mechanisms forbidden by `ByPrecedence`: were available at an earlier + /// step but not chosen. Cannot be added in future steps. + forbidden: Bitset, +} + +impl AStarDecoder { + /// Build from a DEM string (graphlike — 2-detector edges only). + /// + /// # Errors + /// + /// Returns `DecoderError` if the DEM is malformed. + pub fn from_dem(dem: &str, config: AStarConfig) -> Result { + let graph = DemMatchingGraph::from_dem_str(dem)?; + let num_detectors = graph.num_detectors; + + let mut mechanisms = Vec::new(); + let mut det_to_mechs: Vec> = vec![Vec::new(); num_detectors]; + + for edge in &graph.edges { + let mut detectors = vec![edge.node1]; + if let Some(n2) = edge.node2 { + detectors.push(n2); + } + + let obs_mask: u64 = edge + .observables + .iter() + .fold(0u64, |mask, &o| mask | (1 << o)); + + let mech_idx = mechanisms.len(); + for &d in &detectors { + if (d as usize) < num_detectors { + det_to_mechs[d as usize].push(mech_idx); + } + } + + mechanisms.push(Mechanism { + detectors, + obs_mask, + weight: edge.weight, + }); + } + + let num_mechanisms = mechanisms.len(); + + Ok(Self { + mechanisms, + det_to_mechs, + num_detectors, + num_mechanisms, + config, + }) + } + + /// Build from a non-decomposed DEM (preserves hyperedges with 3+ detectors). + /// + /// This gives the A* search access to the full error structure including + /// Y-error correlations that decomposition loses. + /// + /// # Errors + /// + /// Returns `DecoderError` if the DEM is malformed. + pub fn from_dem_full(dem: &str, config: AStarConfig) -> Result { + use pecos_decoder_core::dem::DemCheckMatrix; + + let dcm = DemCheckMatrix::from_dem_str(dem) + .map_err(|e| DecoderError::InvalidGraph(e.to_string()))?; + let num_detectors = dcm.num_detectors; + + let mut mechanisms = Vec::new(); + let mut det_to_mechs: Vec> = vec![Vec::new(); num_detectors]; + + for m in 0..dcm.num_mechanisms { + let p = dcm.error_priors[m]; + if p <= 0.0 { + continue; + } + + let detectors: Vec = (0..dcm.num_detectors) + .filter(|&d| dcm.check_matrix[[d, m]] != 0) + .map(|d| d as u32) + .collect(); + + if detectors.is_empty() { + continue; + } + + let weight = if p < 1.0 { ((1.0 - p) / p).ln() } else { 0.0 }; + + let mut obs_mask = 0u64; + for o in 0..dcm.num_observables { + if dcm.observable_matrix[[o, m]] != 0 { + obs_mask |= 1 << o; + } + } + + let mech_idx = mechanisms.len(); + for &d in &detectors { + if (d as usize) < num_detectors { + det_to_mechs[d as usize].push(mech_idx); + } + } + + mechanisms.push(Mechanism { + detectors, + obs_mask, + weight, + }); + } + + let num_mechanisms = mechanisms.len(); + + for mechs in &mut det_to_mechs { + mechs.sort_by(|&a, &b| { + mechanisms[a] + .weight + .partial_cmp(&mechanisms[b].weight) + .unwrap_or(std::cmp::Ordering::Equal) + }); + } + + Ok(Self { + mechanisms, + det_to_mechs, + num_detectors, + num_mechanisms, + config, + }) + } + + /// Compute `DetCost` heuristic: admissible lower bound on remaining cost. + /// Optimized with early exit: mechanisms per detector are pre-sorted by weight, + /// so once weight exceeds `current_min` * `max_possible_coverage`, we can stop. + fn det_cost(&self, residual: &Bitset, errors: &Bitset) -> f64 { + let mut cost = 0.0; + for (wi, &w) in residual.words.iter().enumerate() { + let mut bits = w; + while bits != 0 { + let bit = bits.trailing_zeros() as usize; + let d = wi * 64 + bit; + bits &= bits - 1; + + if d >= self.num_detectors { + break; + } + + let mut min_cost = f64::INFINITY; + for &m in &self.det_to_mechs[d] { + if errors.get(m) { + continue; + } + let mech = &self.mechanisms[m]; + + // Early skip: if weight / max_coverage >= min_cost, skip. + // max_coverage = number of detectors in this mechanism. + let max_cov = mech.detectors.len() as f64; + if max_cov > 0.0 && mech.weight / max_cov >= min_cost { + continue; + } + + let coverage = mech + .detectors + .iter() + .filter(|&&dd| { + (dd as usize) < self.num_detectors && residual.get(dd as usize) + }) + .count(); + if coverage > 0 { + let c = mech.weight / coverage as f64; + if c < min_cost { + min_cost = c; + } + } + } + if min_cost < f64::INFINITY { + cost += min_cost; + } + } + } + cost + } +} + +impl ObservableDecoder for AStarDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + let n = self.num_detectors; + let m = self.num_mechanisms; + + // Build initial residual. + let mut init_residual = Bitset::new(n); + for (i, &v) in syndrome.iter().enumerate() { + if v != 0 && i < n { + init_residual.set(i); + } + } + let num_defects = init_residual.count_ones(); + if num_defects == 0 { + return Ok(0); + } + + // A* priority queue and visited set. + let mut pq: BinaryHeap<(Reverse, usize)> = BinaryHeap::new(); + let mut states: Vec = Vec::new(); + let mut visited: HashSet = HashSet::new(); + + let init_errors = Bitset::new(m); + let init_h = self.det_cost(&init_residual, &init_errors); + + states.push(SearchState { + errors: init_errors, + residual: init_residual.clone(), + num_residual: num_defects, + g_cost: 0.0, + obs_mask: 0, + det_error_count: vec![0u8; n], + forbidden: Bitset::new(m), + }); + pq.push((Reverse((0.0_f64 + init_h).to_bits()), 0)); + visited.insert(init_residual); + + let mut best_obs = 0u64; + let best_cost = f64::INFINITY; + let mut min_residual = num_defects; + let mut pops = 0; + + while let Some((Reverse(_), state_idx)) = pq.pop() { + pops += 1; + if pops > self.config.pq_limit { + break; + } + + // Extract state data (avoids borrow conflict). + let (s_num_res, s_g_cost, s_obs) = { + let s = &states[state_idx]; + (s.num_residual, s.g_cost, s.obs_mask) + }; + + if s_num_res == 0 { + best_obs = s_obs; + break; // A* first solution is optimal (admissible heuristic). + } + + if s_num_res > min_residual + self.config.beam { + continue; + } + if s_num_res < min_residual { + min_residual = s_num_res; + } + + // Clone for expansion. + let (s_errors, s_residual, s_det_counts, s_forbidden) = { + let s = &states[state_idx]; + ( + s.errors.clone(), + s.residual.clone(), + s.det_error_count.clone(), + s.forbidden.clone(), + ) + }; + + let lowest_det = match s_residual.lowest_set() { + Some(d) if d < n => d, + _ => continue, + }; + + // Collect candidate mechanisms incident to lowest_det. + let candidates: Vec = self.det_to_mechs[lowest_det] + .iter() + .copied() + .filter(|&mi| !s_errors.get(mi) && !s_forbidden.get(mi)) + .collect(); + + for &mech_idx in &candidates { + let mech = &self.mechanisms[mech_idx]; + + // AtMostTwo: skip if adding this mechanism would place >2 errors + // on any single detector. + let at_most_two_ok = mech.detectors.iter().all(|&d| { + let di = d as usize; + di >= n || s_det_counts[di] < 2 + }); + if !at_most_two_ok { + continue; + } + + let mut new_residual = s_residual.clone(); + let mut new_num = s_num_res; + let mut new_det_counts = s_det_counts.clone(); + for &d in &mech.detectors { + let di = d as usize; + if di < n { + if new_residual.get(di) { + new_num -= 1; + } else { + new_num += 1; + } + new_residual.flip(di); + new_det_counts[di] += 1; + } + } + + // ByPrecedence: all other candidate mechanisms at this step + // become forbidden for this child. They were available but not chosen. + let mut new_forbidden = s_forbidden.clone(); + for &other in &candidates { + if other != mech_idx { + new_forbidden.set(other); + } + } + + // No-revisit-dets: skip if we've seen this residual before. + if !visited.insert(new_residual.clone()) { + continue; + } + + let mut new_errors = s_errors.clone(); + new_errors.set(mech_idx); + + let new_g = s_g_cost + mech.weight; + let new_h = self.det_cost(&new_residual, &new_errors); + let new_f = new_g + new_h; + + if new_f >= best_cost { + continue; + } + + let idx = states.len(); + states.push(SearchState { + errors: new_errors, + residual: new_residual, + num_residual: new_num, + g_cost: new_g, + obs_mask: s_obs ^ mech.obs_mask, + det_error_count: new_det_counts, + forbidden: new_forbidden, + }); + pq.push((Reverse(new_f.to_bits()), idx)); + } + } + + Ok(best_obs) + } +} + +#[cfg(test)] +mod tests { + use super::*; + + const D3_DEM: &str = + include_str!("../../../examples/surface_code_circuits/surface_code_d3_z_stim.dem"); + + #[test] + fn test_astar_construction() { + let dec = AStarDecoder::from_dem(D3_DEM, AStarConfig::default()); + assert!(dec.is_ok()); + } + + #[test] + fn test_astar_no_errors() { + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let mut dec = AStarDecoder::from_dem(D3_DEM, AStarConfig::default()).unwrap(); + let obs = dec + .decode_to_observables(&vec![0u8; graph.num_detectors]) + .unwrap(); + assert_eq!(obs, 0); + } + + #[test] + fn test_astar_single_defect() { + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let mut dec = AStarDecoder::from_dem(D3_DEM, AStarConfig::default()).unwrap(); + let mut syn = vec![0u8; graph.num_detectors]; + syn[0] = 1; + // Should not panic — single defect resolves to boundary. + let _obs = dec.decode_to_observables(&syn).unwrap(); + } +} diff --git a/crates/pecos-uf-decoder/src/bp_uf.rs b/crates/pecos-uf-decoder/src/bp_uf.rs new file mode 100644 index 000000000..a224ea6fe --- /dev/null +++ b/crates/pecos-uf-decoder/src/bp_uf.rs @@ -0,0 +1,611 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! BP+UF hybrid decoder. +//! +//! Runs truncated min-sum BP to get per-mechanism soft reliability scores, +//! then uses those scores to adjust UF edge weights. Mechanisms that BP +//! identifies as likely errors get lower weights in UF, improving the +//! quality of the UF clustering. +//! +//! This is a three-stage decoder: +//! 1. **BP stage**: 3-5 iterations of min-sum BP on the check matrix +//! 2. **Weight adjustment**: map BP posteriors to UF edge weights +//! 3. **UF stage**: standard weighted UF growth + peeling + +use crate::decoder::{UfDecoder, UfDecoderConfig}; +use crate::mini_bp::{self, BpGraph}; +use pecos_decoder_core::dem::{DemCheckMatrix, DemMatchingGraph}; +use pecos_decoder_core::errors::DecoderError; + +/// BP message schedule. +#[derive(Debug, Clone, Copy, Default)] +pub enum BpSchedule { + /// Flooding: update all checks, then all variables. Fast, good for d<=7. + #[default] + Flooding, + /// Serial: after each check update, immediately update connected variables. + /// Better convergence on loopy graphs. Slower but maintains threshold at d>=9. + Serial, +} + +/// Which graph to run BP on. +#[derive(Debug, Clone, Copy, Default)] +pub enum BpGraphType { + /// Auto: matching-graph BP at d<=4, Tanner-graph BP at d>=5. + /// Gets the best of both worlds at each distance. + #[default] + Auto, + /// Tanner graph from check matrix (decomposed DEM). + TannerGraph, + /// Matching graph (pairwise detector edges). Simpler topology, + /// better convergence. Based on Hack et al. (2026). + MatchingGraph, +} + +/// Configuration for the BP+UF hybrid decoder. +#[derive(Debug, Clone, Copy)] +pub struct BpUfConfig { + /// Number of BP iterations before UF. + /// 0 = adaptive (scales with code distance). Default: 0. + pub bp_iterations: usize, + /// BP message schedule. Default: Flooding (fast, good for d<=7). + pub bp_schedule: BpSchedule, + /// Which graph to run BP on. Default: `TannerGraph`. + pub bp_graph_type: BpGraphType, + /// Min-sum scaling factor. Default: 0.625 (normalized min-sum). + pub min_sum_scale: f64, + /// How much BP posteriors influence UF weights. + /// 0.0 = pure UF, 1.0 = fully trust BP. Default: 0.9. + pub bp_weight_blend: f64, + /// UF decoder config. + pub uf_config: UfDecoderConfig, +} + +impl Default for BpUfConfig { + fn default() -> Self { + Self::balanced() + } +} + +impl BpUfConfig { + /// Balanced: flooding BP on Tanner graph, good for d=3-7. Fast. + #[must_use] + pub fn balanced() -> Self { + Self { + bp_iterations: 0, + bp_schedule: BpSchedule::Flooding, + bp_graph_type: BpGraphType::Auto, + min_sum_scale: 0.625, + bp_weight_blend: 0.9, + uf_config: UfDecoderConfig::balanced(), + } + } + + /// Accurate: serial BP, maintains threshold at d=7-11+. Slower. + #[must_use] + pub fn accurate() -> Self { + Self { + bp_iterations: 0, + bp_schedule: BpSchedule::Serial, + bp_graph_type: BpGraphType::Auto, + min_sum_scale: 0.625, + bp_weight_blend: 0.9, + uf_config: UfDecoderConfig::balanced(), + } + } + + /// Matching-graph BP: run BP on the simpler matching graph. + #[must_use] + pub fn matching_bp() -> Self { + Self { + bp_iterations: 0, + bp_schedule: BpSchedule::Flooding, + bp_graph_type: BpGraphType::MatchingGraph, + min_sum_scale: 0.625, + bp_weight_blend: 0.9, + uf_config: UfDecoderConfig::balanced(), + } + } +} + +/// BP+UF hybrid decoder. +pub struct BpUfDecoder { + /// Inner UF decoder. + uf: UfDecoder, + /// Pre-computed sparse BP graph for Tanner graph BP. + bp_graph: BpGraph, + /// Matching graph (stored for matching-graph BP mode). + matching_graph: Option, + /// Mapping from mechanism index to matching graph edge index. + mechanism_to_edge: Vec>, + /// Base edge weights (from DEM, before BP adjustment). + base_weights: Vec, + /// BP-adjusted weights (reusable buffer). + adjusted_weights: Vec, + /// BP message buffers (reusable across shots). + bp_c_to_v: Vec, + bp_v_to_c: Vec, + bp_posterior: Vec, + /// Config. + config: BpUfConfig, +} + +impl BpUfDecoder { + /// Create from a DEM string. + /// + /// # Errors + /// + /// Returns `DecoderError` if the DEM is malformed. + pub fn from_dem(dem: &str, config: BpUfConfig) -> Result { + let dcm = DemCheckMatrix::from_dem_str(dem) + .map_err(|e| DecoderError::InvalidConfiguration(e.to_string()))?; + let graph = DemMatchingGraph::from_dem_str(dem)?; + let uf = UfDecoder::from_matching_graph(&graph, config.uf_config); + + // Build mechanism → edge mapping. + // Each mechanism in the check matrix corresponds to a column. + // The matching graph merges mechanisms by fault ID into edges. + // We need to find which edge each mechanism ended up in. + // + // Approach: for each mechanism, find which detectors it touches, + // then find the matching edge connecting those detectors. + let mut mechanism_to_edge = vec![None; dcm.num_mechanisms]; + + for m in 0..dcm.num_mechanisms { + let mut detectors: Vec = Vec::new(); + for d in 0..dcm.num_detectors { + if dcm.check_matrix[[d, m]] != 0 { + detectors.push(d as u32); + } + } + + // Match to graph edge by detector pair. + match detectors.len() { + 1 => { + // Boundary edge: one detector. + let d0 = detectors[0]; + for (idx, edge) in graph.edges.iter().enumerate() { + if edge.node1 == d0 && edge.node2.is_none() { + mechanism_to_edge[m] = Some(idx); + break; + } + } + } + 2 => { + // Internal edge: two detectors. + let (d0, d1) = (detectors[0], detectors[1]); + for (idx, edge) in graph.edges.iter().enumerate() { + if (edge.node1 == d0 && edge.node2 == Some(d1)) + || (edge.node1 == d1 && edge.node2 == Some(d0)) + { + mechanism_to_edge[m] = Some(idx); + break; + } + } + } + _ => { + // Hyperedge (3+ detectors): skip, no matching graph edge. + } + } + } + + let base_weights: Vec = graph.edges.iter().map(|e| e.weight).collect(); + let adjusted_weights = base_weights.clone(); + + let bp_graph_data = BpGraph::from_dcm(&dcm); + let bp_c_to_v = vec![0.0; bp_graph_data.total_edges]; + let bp_v_to_c = vec![0.0; bp_graph_data.total_edges]; + let bp_posterior = Vec::with_capacity(bp_graph_data.num_vars); + + // Always store matching graph (needed for Auto and MatchingGraph modes). + let matching_graph_stored = Some(graph); + + Ok(Self { + uf, + bp_graph: bp_graph_data, + matching_graph: matching_graph_stored, + mechanism_to_edge, + base_weights, + adjusted_weights, + bp_c_to_v, + bp_v_to_c, + bp_posterior, + config, + }) + } +} + +impl BpUfDecoder { + /// Create from two DEMs: non-decomposed for BP, decomposed for matching graph. + /// + /// The non-decomposed DEM gives BP cleaner soft info (no decomposition + /// artifacts). The decomposed DEM gives the matching graph edge structure + /// needed for MWPM and correlation tables. + /// + /// # Errors + /// + /// Returns `DecoderError` if either DEM is malformed. + pub fn from_dual_dem( + bp_dem: &str, + matching_dem: &str, + config: BpUfConfig, + ) -> Result { + // BP graph from the non-decomposed DEM. + let bp_dcm = DemCheckMatrix::from_dem_str(bp_dem) + .map_err(|e| DecoderError::InvalidConfiguration(e.to_string()))?; + let bp_graph = BpGraph::from_dcm(&bp_dcm); + + // Matching graph and UF from the decomposed DEM. + let match_graph = DemMatchingGraph::from_dem_str(matching_dem)?; + let uf = UfDecoder::from_matching_graph(&match_graph, config.uf_config); + + // Map BP mechanisms (non-decomposed) → matching graph edges (decomposed). + let mut mechanism_to_edge = vec![None; bp_dcm.num_mechanisms]; + for m in 0..bp_dcm.num_mechanisms { + let mut detectors: Vec = Vec::new(); + for d in 0..bp_dcm.num_detectors { + if bp_dcm.check_matrix[[d, m]] != 0 { + detectors.push(d as u32); + } + } + match detectors.len() { + 1 => { + let d0 = detectors[0]; + for (idx, edge) in match_graph.edges.iter().enumerate() { + if edge.node1 == d0 && edge.node2.is_none() { + mechanism_to_edge[m] = Some(idx); + break; + } + } + } + 2 => { + let (d0, d1) = (detectors[0], detectors[1]); + for (idx, edge) in match_graph.edges.iter().enumerate() { + if (edge.node1 == d0 && edge.node2 == Some(d1)) + || (edge.node1 == d1 && edge.node2 == Some(d0)) + { + mechanism_to_edge[m] = Some(idx); + break; + } + } + } + _ => {} // Hyperedge + } + } + + let base_weights: Vec = match_graph.edges.iter().map(|e| e.weight).collect(); + let adjusted_weights = base_weights.clone(); + let total_edges = bp_graph.total_edges; + + Ok(Self { + uf, + bp_graph, + matching_graph: None, // dual_dem mode uses Tanner graph BP + mechanism_to_edge, + base_weights, + adjusted_weights, + bp_c_to_v: vec![0.0; total_edges], + bp_v_to_c: vec![0.0; total_edges], + bp_posterior: Vec::with_capacity(bp_dcm.num_mechanisms), + config, + }) + } +} + +impl pecos_decoder_core::bp_matching::BpWeightProvider for BpUfDecoder { + fn compute_weights(&mut self, syndrome: &[u8]) -> Vec { + let num_defects = syndrome.iter().filter(|&&v| v != 0).count(); + + let iters = if self.config.bp_iterations > 0 { + self.config.bp_iterations + } else { + let d_est = ((self + .matching_graph + .as_ref() + .map_or(self.bp_graph.num_checks, |mg| mg.num_detectors) + as f64) + / 2.0) + .sqrt(); + match num_defects { + 2..=3 => (d_est.ceil() as usize).min(3), + 4..=8 => (d_est.ceil() as usize).min(8), + _ => (d_est.ceil() as usize).min(12), + } + }; + + // Estimate code distance from matching graph detectors. + // For surface codes: num_detectors ≈ num_stab * num_rounds ≈ d * 2d = 2d² + // so d ≈ sqrt(num_detectors / 2). + let num_det = self + .matching_graph + .as_ref() + .map_or(self.bp_graph.num_checks, |mg| mg.num_detectors); + let d_est = ((num_det as f64) / 2.0).sqrt(); + let use_matching_graph = match self.config.bp_graph_type { + BpGraphType::MatchingGraph => true, + BpGraphType::TannerGraph => false, + BpGraphType::Auto => d_est < 5.5, // Matching graph at d<=4 (d_est≈4.9 at d=3) + }; + + if let (true, Some(mg)) = (use_matching_graph, &self.matching_graph) { + // Matching-graph BP: simpler topology, better convergence. + self.bp_posterior = + mini_bp::matching_graph_bp(mg, syndrome, iters, self.config.min_sum_scale); + // Matching-graph BP posteriors are already per-edge (no mechanism mapping needed). + // Return them directly as weights. + let mut weights = self.base_weights.clone(); + let d_est = ((self + .matching_graph + .as_ref() + .map_or(self.bp_graph.num_checks, |mg| mg.num_detectors) + as f64) + / 2.0) + .sqrt(); + let selectivity = 0.2 * d_est.max(1.0) / 3.0; + for (edge_idx, &posterior) in self.bp_posterior.iter().enumerate() { + if edge_idx < weights.len() { + let prior = self.base_weights[edge_idx]; + let shift = (posterior - prior).abs(); + if shift > selectivity * prior.abs().max(0.1) { + let bp_weight = if posterior > 10.0 { + posterior + } else if posterior < -10.0 { + 0.01 + } else { + (1.0 + posterior.exp()).ln() + }; + let blend = 0.5; + weights[edge_idx] = (1.0 - blend) * prior + blend * bp_weight; + } + } + } + return weights; + } + + // At d>=5 with auto mode, selective BP rarely adjusts edges. + // Skip BP entirely and return base weights (= FB_correlated behavior). + // The correlation table second pass in BpMatchingDecoder handles accuracy. + if matches!(self.config.bp_graph_type, BpGraphType::Auto) && d_est >= 5.5 { + return self.base_weights.clone(); + } + + // Tanner-graph BP. + self.bp_c_to_v.fill(0.0); + self.bp_v_to_c.fill(0.0); + let serial = matches!(self.config.bp_schedule, BpSchedule::Serial); + mini_bp::min_sum_bp_into( + &self.bp_graph, + syndrome, + iters, + self.config.min_sum_scale, + serial, + &mut self.bp_c_to_v, + &mut self.bp_v_to_c, + &mut self.bp_posterior, + ); + + // Selective BP: only adjust edges where BP strongly disagrees with + // the DEM prior. This avoids BP noise (which hurts at d>=5) while + // capturing genuine syndrome-dependent information for edges where + // BP has high confidence. + // + // An edge is adjusted if |posterior - prior| > threshold * |prior|. + // This means BP must shift the LLR by a significant fraction of the + // prior to be trusted. + let mut weights = self.base_weights.clone(); + let d_est = ((self + .matching_graph + .as_ref() + .map_or(self.bp_graph.num_checks, |mg| mg.num_detectors) as f64) + / 2.0) + .sqrt(); + // Selectivity threshold: higher at large d (BP less reliable). + // At d=3: threshold=0.3 (accept moderate BP shifts). + // At d=7: threshold=0.8 (only trust strong BP shifts). + // At d=11: threshold=1.2 (very selective). + let selectivity = 0.2 * d_est.max(1.0) / 3.0; + + for (m, &posterior) in self.bp_posterior.iter().enumerate() { + if let Some(edge_idx) = self.mechanism_to_edge[m] { + let prior = self.bp_graph.prior_llr[m]; + let shift = (posterior - prior).abs(); + + // Only use BP weight if the shift is large relative to the prior. + if shift > selectivity * prior.abs().max(0.1) { + let bp_weight = if posterior > 10.0 { + posterior + } else if posterior < -10.0 { + 0.01 + } else { + (1.0 + posterior.exp()).ln() + }; + // Blend with a moderate factor for selected edges. + let blend = 0.5; + let blended = (1.0 - blend) * self.base_weights[edge_idx] + blend * bp_weight; + weights[edge_idx] = weights[edge_idx].min(blended); + } + } + } + weights + } + + fn num_edges(&self) -> usize { + self.base_weights.len() + } + + fn is_trivial(&self, syndrome: &[u8]) -> Option { + self.uf.predecode_clusters(syndrome) + } +} + +impl pecos_decoder_core::ObservableDecoder for BpUfDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + // Fast path: cluster predecoder handles isolated cases without BP. + // This catches 0 defects, single defects, and isolated pairs. + if let Some(obs) = self.uf.predecode_clusters(syndrome) { + return Ok(obs); + } + + let num_defects = syndrome.iter().filter(|&&v| v != 0).count(); + + // Stage 1: Run truncated BP (reusing pre-allocated buffers). + // Adaptive iterations: need enough for messages to propagate + // across the graph, but not so many that BP oscillates. + let iters = if self.config.bp_iterations > 0 { + self.config.bp_iterations + } else { + // Estimate code distance from detector count. + // Surface code: num_detectors ≈ d * num_rounds, num_rounds ≈ 2d + // So num_detectors ≈ 2d^2, d ≈ sqrt(num_det / 2) + let d_est = ((self + .matching_graph + .as_ref() + .map_or(self.bp_graph.num_checks, |mg| mg.num_detectors) + as f64) + / 2.0) + .sqrt(); + // Need ~d iterations for full propagation. + // Scale down for few defects. + let target = d_est.ceil() as usize; + match num_defects { + 2..=3 => target.min(3), // few defects: local info sufficient + 4..=8 => target.min(8), // moderate: need more propagation + _ => target.min(12), // many defects: full propagation, capped + } + }; + + self.bp_c_to_v.fill(0.0); + self.bp_v_to_c.fill(0.0); + let serial = matches!(self.config.bp_schedule, BpSchedule::Serial); + mini_bp::min_sum_bp_into( + &self.bp_graph, + syndrome, + iters, + self.config.min_sum_scale, + serial, + &mut self.bp_c_to_v, + &mut self.bp_v_to_c, + &mut self.bp_posterior, + ); + let posteriors = &self.bp_posterior; + + // Stage 2: Adjust UF edge weights using BP posteriors. + // + // BP posterior is an LLR: positive = likely no error, negative = likely error. + // UF weight = ln((1-p)/p): positive, lower = more likely error. + // Both are LLRs with the same sign convention. + // + // The posterior directly replaces the prior LLR as a better estimate. + // We blend to avoid over-reliance on BP when it hasn't converged. + self.adjusted_weights.copy_from_slice(&self.base_weights); + + let blend = self.config.bp_weight_blend; + for (m, &posterior) in posteriors.iter().enumerate() { + if let Some(edge_idx) = self.mechanism_to_edge[m] { + // Map posterior LLR to positive UF weight. + // Positive posterior = unlikely error = high weight. + // Negative posterior = likely error = low weight. + // Soft mapping: weight = log(1 + exp(posterior)) keeps + // weights positive and smooth, approaching 0 for very + // negative posteriors and linear for positive ones. + let bp_weight = if posterior > 10.0 { + posterior // Avoid overflow in exp + } else if posterior < -10.0 { + 0.01 // Very likely error + } else { + (1.0 + posterior.exp()).ln() + }; + let blended = (1.0 - blend) * self.base_weights[edge_idx] + blend * bp_weight; + // Take the minimum across mechanisms for this edge. + self.adjusted_weights[edge_idx] = self.adjusted_weights[edge_idx].min(blended); + } + } + + // Stage 3: Use UF with BP-adjusted weights. + use pecos_decoder_core::correlated_decoder::MatchingDecoder; + let (mask, matched_edges) = self + .uf + .decode_with_weights(syndrome, &self.adjusted_weights)?; + + // Stage 4 (optional): Second pass -- use first-pass correction to + // boost BP priors for matched edges, re-run BP, re-decode. + // Only do this when the first pass found a substantial correction + // and BP had enough iterations to produce meaningful posteriors. + if matched_edges.len() >= 2 && iters >= 4 { + let boost = 1.5; + for &edge_idx in &matched_edges { + if edge_idx < self.adjusted_weights.len() { + self.adjusted_weights[edge_idx] = + (self.adjusted_weights[edge_idx] - boost).max(0.01); + } + } + let (mask2, _) = self + .uf + .decode_with_weights(syndrome, &self.adjusted_weights)?; + return Ok(mask2); + } + + Ok(mask) + } +} + +#[cfg(test)] +mod tests { + use super::*; + use pecos_decoder_core::ObservableDecoder; + + const SIMPLE_DEM: &str = "\ +error(0.1) D0 D1 L0 +error(0.1) D1 +"; + + #[test] + fn test_bp_uf_construction() { + let dec = BpUfDecoder::from_dem(SIMPLE_DEM, BpUfConfig::default()); + assert!(dec.is_ok()); + } + + #[test] + fn test_bp_uf_no_errors() { + let mut dec = BpUfDecoder::from_dem(SIMPLE_DEM, BpUfConfig::default()).unwrap(); + let obs = dec.decode_to_observables(&[0, 0]).unwrap(); + assert_eq!(obs, 0); + } + + #[test] + fn test_bp_uf_with_errors() { + let mut dec = BpUfDecoder::from_dem(SIMPLE_DEM, BpUfConfig::default()).unwrap(); + let obs = dec.decode_to_observables(&[1, 1]).unwrap(); + assert_eq!(obs, 1); // D0-D1 edge carries L0 + } + + const D3_DEM: &str = + include_str!("../../../examples/surface_code_circuits/surface_code_d3_z_stim.dem"); + + #[test] + fn test_bp_uf_real_dem() { + let mut dec = BpUfDecoder::from_dem(D3_DEM, BpUfConfig::default()).unwrap(); + // No errors + let obs = dec.decode_to_observables(&[0u8; 24]).unwrap(); + assert_eq!(obs, 0); + + // Random syndromes shouldn't panic + let mut rng = fastrand::Rng::with_seed(42); + for _ in 0..100 { + let syn: Vec = (0..24) + .map(|_| u8::from(rng.f64() < 0.05)) + .collect(); + let _ = dec.decode_to_observables(&syn).unwrap(); + } + } +} diff --git a/crates/pecos-uf-decoder/src/css_decoder.rs b/crates/pecos-uf-decoder/src/css_decoder.rs new file mode 100644 index 000000000..69baaf239 --- /dev/null +++ b/crates/pecos-uf-decoder/src/css_decoder.rs @@ -0,0 +1,382 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! CSS-aware Union-Find decoder using the UIUF (Union-Intersection) algorithm. +//! +//! Exploits the CSS structure of surface codes by running UF independently on +//! X and Z syndrome graphs, then identifying likely Y errors via intersection +//! of the two cluster sets. Y errors are promoted to erasures, dramatically +//! improving accuracy (matching or exceeding MWPM). +//! +//! Reference: Tzu-Hao Lin and Ching-Yi Lai, "Union-Intersection Union-Find +//! Decoder," arXiv:2506.14745 (2025). +//! +//! This decoder takes TWO DEM strings (one for X-basis, one for Z-basis) and +//! decodes them jointly. + +use crate::decoder::{UfDecoder, UfDecoderConfig}; +use pecos_decoder_core::dem::{DemMatchingGraph, MatchingEdge}; +use pecos_decoder_core::errors::DecoderError; + +/// Compute the quantized spatial midpoint of an edge from detector coordinates. +/// +/// For UIUF cross-graph matching, we use only the spatial coordinates +/// (first two dimensions) and ignore time (third dimension), since X and Z +/// stabilizers are measured at different times but share the same data qubits. +/// +/// For same-time edges (timelike = measurement errors), the two endpoints +/// share spatial coords, so the midpoint is just that shared spatial position. +/// For space edges (data qubit errors), the midpoint is the data qubit's +/// spatial position. +/// +/// Quantized to 0.001 resolution for use as a map key. +fn edge_spatial_midpoint(edge: &MatchingEdge, coords: &[Option>]) -> Option<(i64, i64)> { + let c1 = coords.get(edge.node1 as usize)?.as_ref()?; + + if let Some(n2) = edge.node2 { + let c2 = coords.get(n2 as usize)?.as_ref()?; + // Spatial midpoint only (ignore time dimension). + let x = ((c1.first().unwrap_or(&0.0) + c2.first().unwrap_or(&0.0)) * 500.0) as i64; + let y = ((c1.get(1).unwrap_or(&0.0) + c2.get(1).unwrap_or(&0.0)) * 500.0) as i64; + Some((x, y)) + } else { + // Boundary edge. + let x = (c1.first().unwrap_or(&0.0) * 1000.0) as i64; + let y = (c1.get(1).unwrap_or(&0.0) * 1000.0) as i64; + Some((x, y)) + } +} + +/// Check if an edge is spatial (connects detectors at the same time) +/// vs timelike (connects detectors at different times). +/// Only spatial edges correspond to data qubit errors. +fn is_spatial_edge(edge: &MatchingEdge, coords: &[Option>]) -> bool { + let Some(c1) = coords.get(edge.node1 as usize).and_then(|c| c.as_ref()) else { + return true; // Assume spatial if no coords. + }; + let Some(n2) = edge.node2 else { + return true; // Boundary edges are spatial. + }; + let Some(c2) = coords.get(n2 as usize).and_then(|c| c.as_ref()) else { + return true; + }; + let t1 = c1.get(2).unwrap_or(&0.0); + let t2 = c2.get(2).unwrap_or(&0.0); + (t1 - t2).abs() < 0.01 // Same time = spatial edge +} + +/// Mapping of shared qubits between X and Z decoding graphs. +/// +/// Each entry represents a data qubit that appears as an edge in both +/// the X and Z matching graphs. During UIUF intersection, if both +/// edges are covered by clusters, the qubit is marked as an erasure. +#[derive(Debug, Clone)] +pub struct QubitEdgeMapping { + /// For each shared qubit: `(edge_idx in X graph, edge_idx in Z graph)`. + pub pairs: Vec<(usize, usize)>, +} + +/// CSS-aware UF decoder using UIUF intersection. +/// +/// Wraps two `UfDecoder` instances (X and Z basis) and exploits the +/// overlap between their cluster sets to identify Y errors. +pub struct CssUfDecoder { + /// UF decoder for X-basis syndromes (decodes Z errors). + x_decoder: UfDecoder, + /// UF decoder for Z-basis syndromes (decodes X errors). + z_decoder: UfDecoder, + /// Number of X detectors (split point for concatenated syndromes). + x_num_detectors: usize, + /// Qubit-to-edge mapping for intersection step. + qubit_map: Option, +} + +impl CssUfDecoder { + /// Create from two DEM strings (X-basis and Z-basis). + /// + /// # Errors + /// + /// Returns `DecoderError` if either DEM is malformed. + pub fn from_dems( + x_dem: &str, + z_dem: &str, + config: UfDecoderConfig, + ) -> Result { + let x_graph = DemMatchingGraph::from_dem_str(x_dem)?; + let z_graph = DemMatchingGraph::from_dem_str(z_dem)?; + + // Auto-detect qubit-edge mapping from detector coordinates. + let qubit_map = Self::build_qubit_mapping(&x_graph, &z_graph); + + let x_num_detectors = x_graph.num_detectors; + let x_decoder = UfDecoder::from_matching_graph(&x_graph, config); + let z_decoder = UfDecoder::from_matching_graph(&z_graph, config); + + Ok(Self { + x_decoder, + z_decoder, + x_num_detectors, + qubit_map, + }) + } + + /// Build qubit-edge mapping by matching spatial edge midpoints across graphs. + /// + /// Only spatial edges (same-time endpoints = data qubit errors) are matched. + /// Timelike edges (measurement errors) are excluded since they don't + /// correspond to shared data qubits. + /// + /// The mapping pairs edges in the X and Z graphs whose spatial midpoints + /// coincide, identifying the shared data qubit. + fn build_qubit_mapping( + x_graph: &DemMatchingGraph, + z_graph: &DemMatchingGraph, + ) -> Option { + use std::collections::BTreeMap; + + // Collect spatial edges from X graph, keyed by spatial midpoint. + // Multiple X edges can share the same midpoint (different time slices). + // We store all of them and match greedily. + let mut x_midpoints: BTreeMap<(i64, i64), Vec> = BTreeMap::new(); + + for (idx, edge) in x_graph.edges.iter().enumerate() { + if !is_spatial_edge(edge, &x_graph.detector_coords) { + continue; + } + if let Some(mid) = edge_spatial_midpoint(edge, &x_graph.detector_coords) { + x_midpoints.entry(mid).or_default().push(idx); + } + } + + if x_midpoints.is_empty() { + return None; + } + + // Match Z spatial edges against X midpoints. + let mut pairs = Vec::new(); + let mut used_x: std::collections::BTreeSet = std::collections::BTreeSet::new(); + + for (z_idx, edge) in z_graph.edges.iter().enumerate() { + if !is_spatial_edge(edge, &z_graph.detector_coords) { + continue; + } + if let Some(mid) = edge_spatial_midpoint(edge, &z_graph.detector_coords) + && let Some(x_candidates) = x_midpoints.get(&mid) + { + for &x_idx in x_candidates { + if !used_x.contains(&x_idx) { + pairs.push((x_idx, z_idx)); + used_x.insert(x_idx); + break; + } + } + } + } + + if pairs.is_empty() { + None + } else { + Some(QubitEdgeMapping { pairs }) + } + } + + /// Number of qubit pairs in the mapping (0 = no mapping, falls back to independent). + #[must_use] + pub fn num_qubit_pairs(&self) -> usize { + self.qubit_map.as_ref().map_or(0, |m| m.pairs.len()) + } + + /// Set the qubit-to-edge mapping for UIUF intersection. + /// + /// Each pair `(x_edge_idx, z_edge_idx)` identifies a data qubit + /// that appears as an edge in both the X and Z matching graphs. + pub fn set_qubit_mapping(&mut self, mapping: QubitEdgeMapping) { + self.qubit_map = Some(mapping); + } + + /// Decode X and Z syndromes jointly using UIUF. + /// + /// If a qubit-to-edge mapping is set, uses the full UIUF algorithm + /// (intersection to identify Y-error erasures). Otherwise falls back + /// to independent UF decoding on each basis. + /// + /// Returns `(x_obs_mask, z_obs_mask)` -- observable predictions for each basis. + /// + /// # Errors + /// + /// Returns `DecoderError` if decoding fails. + pub fn decode_css( + &mut self, + x_syndrome: &[u8], + z_syndrome: &[u8], + ) -> Result<(u64, u64), DecoderError> { + if let Some(mapping) = &self.qubit_map { + let pairs = mapping.pairs.clone(); + Ok(self.decode_uiuf(x_syndrome, z_syndrome, &pairs)) + } else { + // Fallback: independent decoding. + let x_obs = self.x_decoder.decode_syndrome(x_syndrome); + let z_obs = self.z_decoder.decode_syndrome(z_syndrome); + Ok((x_obs, z_obs)) + } + } + + /// Count erasures that the intersection would produce (diagnostic). + pub fn count_intersection_erasures(&mut self, x_syndrome: &[u8], z_syndrome: &[u8]) -> usize { + if let Some(mapping) = &self.qubit_map { + self.x_decoder.syndrome_validate(x_syndrome); + self.z_decoder.syndrome_validate(z_syndrome); + let mut count = 0; + for &(x_edge, z_edge) in &mapping.pairs { + let x_covered = self.x_decoder.edge_in_cluster(x_edge); + let z_covered = self.z_decoder.edge_in_cluster(z_edge); + if x_covered && z_covered { + count += 1; + } + } + count + } else { + 0 + } + } + + /// Full UIUF algorithm. + fn decode_uiuf( + &mut self, + x_syndrome: &[u8], + z_syndrome: &[u8], + qubit_pairs: &[(usize, usize)], + ) -> (u64, u64) { + // Phase 1: Syndrome validation (growth only) on each graph. + self.x_decoder.syndrome_validate(x_syndrome); + self.z_decoder.syndrome_validate(z_syndrome); + + // Phase 2: Intersection -- find edges covered in BOTH graphs. + // These correspond to likely Y errors (which trigger both X and Z syndromes). + let mut x_erasure_edges: Vec = Vec::new(); + let mut z_erasure_edges: Vec = Vec::new(); + + for &(x_edge, z_edge) in qubit_pairs { + let x_covered = self.x_decoder.edge_in_cluster(x_edge); + let z_covered = self.z_decoder.edge_in_cluster(z_edge); + if x_covered && z_covered { + // Both graphs have clusters covering this qubit's edge. + // Mark as erasure in both graphs for Phase 3. + x_erasure_edges.push(x_edge); + z_erasure_edges.push(z_edge); + } + } + + // Phase 3: Augmented UF decode with erasures. + // X errors are decoded on Z graph (with Z erasures). + // Z errors are decoded on X graph (with X erasures). + let x_obs = self + .x_decoder + .decode_with_erasures(x_syndrome, &x_erasure_edges); + let z_obs = self + .z_decoder + .decode_with_erasures(z_syndrome, &z_erasure_edges); + + (x_obs, z_obs) + } +} + +impl pecos_decoder_core::ObservableDecoder for CssUfDecoder { + /// Decode a concatenated `[x_syndrome | z_syndrome]` via UIUF. + /// + /// The syndrome is split at `x_num_detectors` into X and Z parts. + /// Returns the XOR of both observable masks. + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + let split = self.x_num_detectors; + if syndrome.len() < split { + return Err(DecoderError::DecodingFailed(format!( + "CssUfDecoder: syndrome length {} < x_num_detectors {}", + syndrome.len(), + split + ))); + } + let x_syn = &syndrome[..split]; + let z_syn = &syndrome[split..]; + let (x_obs, z_obs) = self.decode_css(x_syn, z_syn)?; + Ok(x_obs ^ z_obs) + } +} + +#[cfg(test)] +mod tests { + use super::*; + + // Minimal X-basis and Z-basis DEMs for a distance-3 repetition code. + const X_DEM: &str = "\ +error(0.01) D0 D1 L0 +error(0.01) D0 +error(0.01) D1 +"; + + const Z_DEM: &str = "\ +error(0.01) D0 D1 +error(0.01) D0 L0 +error(0.01) D1 +"; + + #[test] + fn test_css_construction() { + let dec = CssUfDecoder::from_dems(X_DEM, Z_DEM, UfDecoderConfig::default()); + assert!(dec.is_ok()); + } + + #[test] + fn test_css_no_errors() { + let mut dec = CssUfDecoder::from_dems(X_DEM, Z_DEM, UfDecoderConfig::default()).unwrap(); + let (x_obs, z_obs) = dec.decode_css(&[0, 0], &[0, 0]).unwrap(); + assert_eq!(x_obs, 0); + assert_eq!(z_obs, 0); + } + + #[test] + fn test_css_with_qubit_mapping() { + let mut dec = CssUfDecoder::from_dems(X_DEM, Z_DEM, UfDecoderConfig::default()).unwrap(); + + // Set up mapping: edge 0 in X_DEM corresponds to edge 0 in Z_DEM + // (same data qubit connecting the two detectors). + dec.set_qubit_mapping(QubitEdgeMapping { + pairs: vec![(0, 0)], + }); + + // No errors: should still decode correctly. + let (x_obs, z_obs) = dec.decode_css(&[0, 0], &[0, 0]).unwrap(); + assert_eq!(x_obs, 0); + assert_eq!(z_obs, 0); + + // Y-error scenario: both X and Z syndromes have the same defects. + // The intersection should identify the qubit as erasure. + let (x_obs, z_obs) = dec.decode_css(&[1, 1], &[1, 1]).unwrap(); + // With erasure, both decoders should handle this correctly. + // The exact observable depends on the DEM structure. + let _ = (x_obs, z_obs); // Just verify no panic. + } + + #[test] + fn test_css_independent_decoding() { + let mut dec = CssUfDecoder::from_dems(X_DEM, Z_DEM, UfDecoderConfig::default()).unwrap(); + + // X syndrome has defects, Z syndrome clean. + let (x_obs, z_obs) = dec.decode_css(&[1, 1], &[0, 0]).unwrap(); + assert_eq!(x_obs, 1); // D0-D1 edge carries L0 in X_DEM + assert_eq!(z_obs, 0); + + // Z syndrome has defects, X syndrome clean. + let (x_obs, z_obs) = dec.decode_css(&[0, 0], &[1, 1]).unwrap(); + assert_eq!(x_obs, 0); + assert_eq!(z_obs, 0); // D0-D1 edge has no observable in Z_DEM + } +} diff --git a/crates/pecos-uf-decoder/src/decoder.rs b/crates/pecos-uf-decoder/src/decoder.rs new file mode 100644 index 000000000..1b96f4ed9 --- /dev/null +++ b/crates/pecos-uf-decoder/src/decoder.rs @@ -0,0 +1,1300 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Syndrome-graph Union-Find decoder implementation. +//! +//! The algorithm (Delfosse-Nickerson style): +//! +//! 1. Each defect detector starts as its own cluster (odd parity). +//! 2. Grow all unsatisfied clusters by radius until an edge becomes fusible. +//! An edge is fusible when the sum of endpoint radii reaches the edge weight. +//! Two growing clusters fuse at half the weight; boundary needs full weight. +//! 3. Fuse all fusible edges, merging clusters. Parity = XOR of components. +//! 4. Repeat until all clusters have even parity or contain the boundary. +//! 5. Peel a spanning forest (BFS from boundary) to extract the correction: +//! an edge is in the correction iff its subtree has odd parity. +//! +//! All data structures are flat arrays. Zero per-shot allocation after init. + +use pecos_decoder_core::dem::DemMatchingGraph; +use pecos_decoder_core::errors::DecoderError; +use std::cmp::Reverse; +use std::collections::BinaryHeap; + +/// Edge in the syndrome graph. +#[derive(Debug, Clone)] +struct Edge { + /// First endpoint node index. + node1: u32, + /// Second endpoint node index (boundary = `num_detectors`). + node2: u32, + /// Weight (log-likelihood ratio). Lower = more likely error. + weight: f64, + /// Observable bitmask for this edge. + obs_mask: u64, +} + +/// Peeling strategy for correction extraction. +#[derive(Debug, Clone, Copy, Default)] +pub enum PeelingStrategy { + /// BFS from boundary. Fastest, slightly less accurate. + Bfs, + /// Prim's MST from boundary. Uses globally lightest edges. + /// Better accuracy, slight heap overhead at small sizes. + #[default] + PrimMst, +} + +/// Growth strategy for cluster expansion. +#[derive(Debug, Clone, Copy, Default)] +pub enum GrowthStrategy { + /// Event-driven with priority queue. Weighted growth (1/size). + /// Best for larger codes (d >= 7). O(E log E) total. + #[default] + EventDriven, + /// Scan-based: find min increment per round, grow all, fuse. + /// Lower constant overhead for small codes (d <= 5). + ScanBased, +} + +/// Configuration for the UF decoder. +/// +/// Use `UfDecoderConfig::fast()`, `::balanced()`, or `::accurate()` for +/// presets, then override individual fields as needed. +#[derive(Debug, Clone, Copy)] +pub struct UfDecoderConfig { + /// Maximum growth rounds before giving up (prevents infinite loops). + /// 0 = auto (100 * `num_detectors`). + pub max_growth_rounds: usize, + /// How to build the spanning forest for peeling. + pub peeling: PeelingStrategy, + /// How to grow clusters. + pub growth: GrowthStrategy, + /// Enable cluster predecoder for simple syndromes. + /// Disable for windowed decoding which needs complete edge tracking. + pub predecoder: bool, +} + +impl Default for UfDecoderConfig { + fn default() -> Self { + Self::fast() + } +} + +impl UfDecoderConfig { + /// Fast preset: event-driven growth, BFS peeling. Lowest latency. + #[must_use] + pub fn fast() -> Self { + Self { + max_growth_rounds: 0, + peeling: PeelingStrategy::Bfs, + growth: GrowthStrategy::EventDriven, + predecoder: true, + } + } + + /// Balanced preset: event-driven weighted growth, Prim MST peeling. + /// Better accuracy, used as inner decoder for two-pass correlated mode. + #[must_use] + pub fn balanced() -> Self { + Self { + max_growth_rounds: 0, + peeling: PeelingStrategy::PrimMst, + growth: GrowthStrategy::EventDriven, + predecoder: true, + } + } + + /// Accurate preset: same as balanced (UIUF accuracy comes from + /// the CSS wrapper, not from single-graph config). + #[must_use] + pub fn accurate() -> Self { + Self::balanced() + } + + /// Windowed preset: Prim MST peeling, no predecoder (need complete edge tracking). + #[must_use] + pub fn windowed() -> Self { + Self { + max_growth_rounds: 0, + peeling: PeelingStrategy::PrimMst, + growth: GrowthStrategy::EventDriven, + predecoder: false, + } + } +} + +/// Fast syndrome-graph Union-Find decoder. +pub struct UfDecoder { + /// Edges in the syndrome graph. + edges: Vec, + /// CSR adjacency: flat data array of (`edge_index`, `neighbor_node`). + adj_data: Vec<(usize, u32)>, + /// CSR adjacency: offset[i]..offset[i+1] is the range in `adj_data` for node i. + adj_offset: Vec, + /// Number of detectors. + num_detectors: usize, + /// Config. + config: UfDecoderConfig, + + // === Per-shot reusable buffers === + /// Disjoint-set forest: parent[i] = parent of node i. + parent: Vec, + /// Rank for union-by-rank. + rank: Vec, + /// Cluster parity: true = odd (needs correction). + parity: Vec, + /// Whether cluster contains the boundary node (satisfied regardless of parity). + has_boundary: Vec, + /// Growth radius of each cluster at `last_growth_time` (tracked at root). + radius: Vec, + /// Time when radius was last updated (for lazy computation). + last_growth_time: Vec, + /// Cluster size (number of nodes, tracked at root). + cluster_size: Vec, + /// Defect flags per detector. + is_defect: Vec, + + // === Scratch buffers (reused across shots to avoid allocation) === + /// Growth event queue. + growth_events: BinaryHeap>, + /// Peeling: tree parent for each node. + tree_parent: Vec>, + /// Peeling: visited flags. + visited: Vec, + /// Peeling: visit order for reverse traversal. + visit_order: Vec, + /// Peeling: priority queue for Prim's MST. + peel_heap: BinaryHeap>, + /// Peeling: subtree parity for each node. + subtree_parity: Vec, + /// Peeling: correction edge indices. + correction_edges: Vec, + /// Weight swap buffer for `decode_with_weights`. + weight_swap: Vec<(usize, f64)>, +} + +impl UfDecoder { + /// Get the adjacency entries for a node (slice into CSR data). + #[inline] + fn adj(&self, node: usize) -> &[(usize, u32)] { + let start = self.adj_offset[node] as usize; + let end = self.adj_offset[node + 1] as usize; + &self.adj_data[start..end] + } + + /// Build from a `DemMatchingGraph`. + #[must_use] + pub fn from_matching_graph(graph: &DemMatchingGraph, config: UfDecoderConfig) -> Self { + let num_detectors = graph.num_detectors; + let num_nodes = num_detectors + 1; + let boundary_node = num_detectors as u32; + + let mut edges = Vec::with_capacity(graph.edges.len()); + // Build temporary adjacency for sorting, then flatten to CSR. + let mut temp_adj: Vec> = vec![Vec::new(); num_nodes]; + + for (idx, me) in graph.edges.iter().enumerate() { + let n1 = me.node1; + let n2 = me.node2.map_or(boundary_node, |n| n); + + let mut obs_mask = 0u64; + for &o in &me.observables { + obs_mask |= 1 << o; + } + + edges.push(Edge { + node1: n1, + node2: n2, + weight: me.weight, + obs_mask, + }); + + temp_adj[n1 as usize].push((idx, n2)); + temp_adj[n2 as usize].push((idx, n1)); + } + + // Sort each node's adjacency by weight (lightest first). + for adj in &mut temp_adj { + adj.sort_by(|a, b| { + edges[a.0] + .weight + .partial_cmp(&edges[b.0].weight) + .unwrap_or(std::cmp::Ordering::Equal) + }); + } + + // Flatten to CSR format. + let total_entries: usize = temp_adj.iter().map(std::vec::Vec::len).sum(); + let mut adj_data = Vec::with_capacity(total_entries); + let mut adj_offset = Vec::with_capacity(num_nodes + 1); + for adj in &temp_adj { + adj_offset.push(adj_data.len() as u32); + adj_data.extend_from_slice(adj); + } + adj_offset.push(adj_data.len() as u32); + + Self { + edges, + adj_data, + adj_offset, + num_detectors, + config, + parent: vec![0; num_nodes], + rank: vec![0; num_nodes], + parity: vec![false; num_nodes], + has_boundary: vec![false; num_nodes], + radius: vec![0.0; num_nodes], + last_growth_time: vec![0.0; num_nodes], + cluster_size: vec![1; num_nodes], + is_defect: vec![false; num_nodes], + growth_events: BinaryHeap::new(), + tree_parent: vec![None; num_nodes], + visited: vec![false; num_nodes], + visit_order: Vec::with_capacity(num_nodes), + peel_heap: BinaryHeap::new(), + subtree_parity: vec![false; num_nodes], + correction_edges: Vec::new(), + weight_swap: Vec::new(), + } + } + + /// Build from a DEM string. + /// + /// # Errors + /// + /// Returns `DecoderError` if the DEM is malformed. + pub fn from_dem(dem: &str, config: UfDecoderConfig) -> Result { + let graph = DemMatchingGraph::from_dem_str(dem)?; + Ok(Self::from_matching_graph(&graph, config)) + } + + /// Reset per-shot state. Uses bulk fill operations for cache efficiency. + fn reset(&mut self) { + let boundary = self.num_detectors; + let n = boundary + 1; + // Bulk-fill each array (SIMD-friendly). + for i in 0..n { + self.parent[i] = i as u32; + } + self.rank[..n].fill(0); + self.parity[..n].fill(false); + self.has_boundary[..n].fill(false); + self.has_boundary[boundary] = true; + self.radius[..n].fill(0.0); + self.last_growth_time[..n].fill(0.0); + self.cluster_size[..n].fill(1); + self.is_defect[..n].fill(false); + } + + /// Find root of node with path halving (one shortcut per step). + fn find(&mut self, mut x: u32) -> u32 { + while self.parent[x as usize] != x { + let grandparent = self.parent[self.parent[x as usize] as usize]; + self.parent[x as usize] = grandparent; + x = grandparent; + } + x + } + + /// Union two clusters. Returns the new root. + fn union(&mut self, a: u32, b: u32) -> u32 { + let ra = self.find(a); + let rb = self.find(b); + if ra == rb { + return ra; + } + + // Union by rank + let (root, child) = if self.rank[ra as usize] >= self.rank[rb as usize] { + (ra, rb) + } else { + (rb, ra) + }; + + self.parent[child as usize] = root; + if self.rank[root as usize] == self.rank[child as usize] { + self.rank[root as usize] += 1; + } + + // XOR parities + self.parity[root as usize] ^= self.parity[child as usize]; + // Propagate boundary membership + self.has_boundary[root as usize] |= self.has_boundary[child as usize]; + // Keep the larger radius + self.radius[root as usize] = self.radius[root as usize].max(self.radius[child as usize]); + // Sum cluster sizes + self.cluster_size[root as usize] += self.cluster_size[child as usize]; + + root + } + + /// Decode a syndrome and return the observable mask. + pub fn decode_syndrome(&mut self, syndrome: &[u8]) -> u64 { + // Try cluster-detection predecoder (if enabled). + if self.config.predecoder + && let Some(obs) = self.predecode_clusters(syndrome) { + return obs; + } + + // Full decoder path for complex syndromes. + self.reset(); + for (i, &v) in syndrome.iter().enumerate() { + if v != 0 && i < self.num_detectors { + self.parity[i] = true; + self.is_defect[i] = true; + } + } + self.grow_clusters(); + self.peel_correction() + } + + /// Cluster-detection predecoder. + /// + /// Finds connected components of defects in the matching graph. + /// - Size-0 components: no defects, return 0. + /// - Size-1 components: match to boundary. + /// - Size-2 components (adjacent pair): match directly if their edge + /// is lighter than both boundary alternatives. + /// - Size 3+: too complex, fall through to full UF. + /// + /// This is provably correct: isolated clusters are independent, so + /// predecoding them individually gives the same result as joint decoding. + #[must_use] + pub fn predecode_clusters(&self, syndrome: &[u8]) -> Option { + let boundary = self.num_detectors as u32; + + // Mark defects. + // Use is_defect buffer conceptually but don't mutate self. + // Instead use a local bitset for small codes. + let mut defect_flags = vec![false; self.num_detectors]; + let mut defect_list: Vec = Vec::new(); + for (i, &v) in syndrome.iter().enumerate() { + if v != 0 && i < self.num_detectors { + defect_flags[i] = true; + defect_list.push(i as u32); + } + } + + if defect_list.is_empty() { + return Some(0); + } + + // Find connected components of defects. + // Two defects are connected if they share an edge in the matching graph. + // Use union-find on defect indices (not the full graph -- just defects). + let n = defect_list.len(); + let mut component: Vec = (0..n).collect(); // parent array + + // For each defect, check if any neighbor is also a defect. + for (di, &d) in defect_list.iter().enumerate() { + for &(_, neighbor) in self.adj(d as usize) { + if neighbor != boundary + && (neighbor as usize) < self.num_detectors + && defect_flags[neighbor as usize] + { + // Find the other defect's index in defect_list. + if let Some(ni) = defect_list.iter().position(|&x| x == neighbor) { + // Union di and ni. + let mut ra = di; + while component[ra] != ra { + ra = component[ra]; + } + let mut rb = ni; + while component[rb] != rb { + rb = component[rb]; + } + if ra != rb { + component[rb] = ra; + } + } + } + } + } + + // Flatten components. + for i in 0..n { + let mut r = i; + while component[r] != r { + r = component[r]; + } + component[i] = r; + } + + // Count component sizes. + let mut comp_size: Vec = vec![0; n]; + for &c in &component { + comp_size[c] += 1; + } + + // Check if any component has 3+ defects -- if so, fall through. + for &s in &comp_size { + if s >= 3 { + return None; // Complex cluster, need full UF. + } + } + + // All components are size 1 or 2. Predecode each. + let mut obs_mask = 0u64; + let mut handled = vec![false; n]; + + for di in 0..n { + if handled[di] { + continue; + } + let root = component[di]; + + if comp_size[root] == 1 { + // Isolated defect: match to boundary. + obs_mask ^= self.predecode_single(defect_list[di]); + handled[di] = true; + } else if comp_size[root] == 2 { + // Find the other defect in this component. + let mut ni = None; + for dj in (di + 1)..n { + if component[dj] == root { + ni = Some(dj); + break; + } + } + let ni = ni?; + + let d0 = defect_list[di]; + let d1 = defect_list[ni]; + + // Find lightest direct edge and lightest boundary alternatives. + let mut direct_w = f64::INFINITY; + let mut direct_obs = 0u64; + for &(e, nbr) in self.adj(d0 as usize) { + if nbr == d1 && self.edges[e].weight < direct_w { + direct_w = self.edges[e].weight; + direct_obs = self.edges[e].obs_mask; + } + } + + let mut b0_w = f64::INFINITY; + let mut b0_obs = 0u64; + for &(e, nbr) in self.adj(d0 as usize) { + if nbr == boundary && self.edges[e].weight < b0_w { + b0_w = self.edges[e].weight; + b0_obs = self.edges[e].obs_mask; + } + } + + let mut b1_w = f64::INFINITY; + let mut b1_obs = 0u64; + for &(e, nbr) in self.adj(d1 as usize) { + if nbr == boundary && self.edges[e].weight < b1_w { + b1_w = self.edges[e].weight; + b1_obs = self.edges[e].obs_mask; + } + } + + // Pick min-weight correction. + if direct_w <= b0_w + b1_w { + obs_mask ^= direct_obs; + } else { + obs_mask ^= b0_obs ^ b1_obs; + } + + handled[di] = true; + handled[ni] = true; + } + } + + Some(obs_mask) + } + + /// Predecode: single defect matches to boundary. + fn predecode_single(&self, defect: u32) -> u64 { + let boundary = self.num_detectors as u32; + // Find the lightest boundary edge from this defect. + // Adjacency is sorted by weight, so iterate and pick first boundary edge. + for &(edge_idx, neighbor) in self.adj(defect as usize) { + if neighbor == boundary { + return self.edges[edge_idx].obs_mask; + } + } + // No boundary edge found (shouldn't happen for valid surface codes). + 0 + } + + /// Returns true if a cluster (given by its root) still needs to grow. + fn is_unsatisfied(&self, root: usize) -> bool { + self.parity[root] && !self.has_boundary[root] + } + + /// Compute the growth rate for a cluster: `1 / size(cluster)`. + /// Smaller clusters grow faster, producing better pairings. + fn growth_rate(&self, root: usize) -> f64 { + 1.0 / f64::from(self.cluster_size[root]) + } + + /// Get the effective radius of a cluster at a given time. + /// Uses lazy computation: radius is only updated when queried. + fn effective_radius(&self, root: usize, current_time: f64) -> f64 { + if self.is_unsatisfied(root) && root != self.num_detectors { + let dt = current_time - self.last_growth_time[root]; + self.radius[root] + dt * self.growth_rate(root) + } else { + self.radius[root] + } + } + + /// Materialize the lazy radius for a cluster (update stored value). + fn materialize_radius(&mut self, root: usize, current_time: f64) { + if self.is_unsatisfied(root) && root != self.num_detectors { + let dt = current_time - self.last_growth_time[root]; + self.radius[root] += dt * self.growth_rate(root); + } + self.last_growth_time[root] = current_time; + } + + /// Compute when edge becomes fusible given current radii and growth rates. + /// Returns the absolute time, or 0 if already fusible. + fn fusible_time(&self, root_u: usize, root_v: usize, weight: f64, current_time: f64) -> f64 { + let r_u = self.effective_radius(root_u, current_time); + let r_v = self.effective_radius(root_v, current_time); + let gap = weight - r_u - r_v; + if gap <= 0.0 { + return current_time; + } + + let u_grows = self.is_unsatisfied(root_u); + let v_grows = self.is_unsatisfied(root_v); + + let combined_rate = if u_grows && v_grows { + self.growth_rate(root_u) + self.growth_rate(root_v) + } else if u_grows { + self.growth_rate(root_u) + } else if v_grows { + self.growth_rate(root_v) + } else { + return f64::INFINITY; // neither grows + }; + + current_time + gap / combined_rate + } + + /// Dispatch to the configured growth strategy. + fn grow_clusters(&mut self) { + match self.config.growth { + GrowthStrategy::EventDriven => self.grow_event_driven(), + GrowthStrategy::ScanBased => self.grow_scan_based(), + } + } + + /// Scan-based growth: simple loop, lower overhead for small codes. + /// + /// Each round: scan all cross-cluster edges to find the minimum growth + /// increment, grow all unsatisfied clusters uniformly, then fuse. + /// O(R * E) where R is the number of growth rounds. + fn grow_scan_based(&mut self) { + let boundary = self.num_detectors; + let max_rounds = if self.config.max_growth_rounds > 0 { + self.config.max_growth_rounds + } else { + 100 * self.num_detectors.max(1) + }; + + for _round in 0..max_rounds { + // Check for any unsatisfied cluster. + let mut any_unsatisfied = false; + for i in 0..=self.num_detectors { + let root = self.find(i as u32) as usize; + if root == i && self.is_unsatisfied(root) { + any_unsatisfied = true; + break; + } + } + if !any_unsatisfied { + break; + } + + // Find the minimum growth increment across all cross-cluster edges. + let mut min_increment = f64::INFINITY; + for node in 0..=self.num_detectors { + let root_u = self.find(node as u32) as usize; + if !self.is_unsatisfied(root_u) { + continue; + } + + let adj_len = self.adj(node).len(); + for adj_i in 0..adj_len { + let (edge_idx, neighbor) = self.adj(node)[adj_i]; + let root_v = self.find(neighbor) as usize; + if root_u == root_v { + continue; + } + + let w = self.edges[edge_idx].weight; + let gap = w - self.radius[root_u] - self.radius[root_v]; + if gap <= 0.0 { + min_increment = 0.0; + break; + } + + let v_grows = self.is_unsatisfied(root_v); + let needed = if v_grows { gap / 2.0 } else { gap }; + min_increment = min_increment.min(needed); + } + if min_increment == 0.0 { + break; + } + } + + if min_increment.is_infinite() { + break; + } + + // Grow all unsatisfied clusters. + for i in 0..=self.num_detectors { + let root = self.find(i as u32) as usize; + if root == i && self.is_unsatisfied(root) && i != boundary { + self.radius[root] += min_increment; + } + } + + // Fuse all now-fusible cross-cluster edges. + // Collect first to avoid borrow issues. + let mut fuse_count = 0; + for node in 0..=self.num_detectors { + let adj_len = self.adj(node).len(); + for adj_i in 0..adj_len { + let (_, neighbor) = self.adj(node)[adj_i]; + let root_u = self.find(node as u32) as usize; + let root_v = self.find(neighbor) as usize; + if root_u == root_v { + continue; + } + let w = self.edges[self.adj(node)[adj_i].0].weight; + if self.radius[root_u] + self.radius[root_v] >= w - 1e-12 { + self.union(node as u32, neighbor); + fuse_count += 1; + } + } + } + if fuse_count == 0 && min_increment == 0.0 { + break; // No progress + } + } + } + + /// Event-driven weighted cluster growth. + /// + /// Smaller clusters grow faster (rate = 1/size), making nearby small + /// clusters fuse before large clusters can absorb them. This improves + /// the quality of the UF pairings. + /// + /// Uses a priority queue with lazy deletion for O(E log E) total work. + fn grow_event_driven(&mut self) { + self.growth_events.clear(); + + // Seed events only from defect nodes (unsatisfied singletons). + // At low error rates, this skips ~95% of nodes. + for node in 0..self.num_detectors { + if !self.is_defect[node] { + continue; + } + + let adj_len = self.adj(node).len(); + for adj_i in 0..adj_len { + let (edge_idx, neighbor) = self.adj(node)[adj_i]; + let root_v = self.find(neighbor) as usize; + if root_v == node { + continue; // same cluster (shouldn't happen for singletons) + } + + let ft = self.fusible_time(node, root_v, self.edges[edge_idx].weight, 0.0); + if ft.is_finite() { + self.growth_events.push(Reverse(( + ft.to_bits(), + edge_idx, + node as u32, + neighbor, + ))); + } + } + } + + let mut current_time: f64; + let max_events = if self.config.max_growth_rounds > 0 { + self.config.max_growth_rounds + } else { + 1000 * self.edges.len().max(1) + }; + let mut events_processed = 0; + + while let Some(Reverse((time_bits, _edge_idx, a, b))) = self.growth_events.pop() { + events_processed += 1; + if events_processed > max_events { + break; + } + let event_time = f64::from_bits(time_bits); + + let root_a = self.find(a) as usize; + let root_b = self.find(b) as usize; + if root_a == root_b { + continue; + } + + let a_unsat = self.is_unsatisfied(root_a); + let b_unsat = self.is_unsatisfied(root_b); + if !a_unsat && !b_unsat { + continue; + } + + current_time = event_time; + + // Materialize radii for the merging clusters (lazy update). + self.materialize_radius(root_a, current_time); + self.materialize_radius(root_b, current_time); + + // Fuse. + let new_root = self.union(a, b) as usize; + self.last_growth_time[new_root] = current_time; + + if !self.is_unsatisfied(new_root) { + continue; + } + + // Re-insert events for edges from the merge nodes with updated times. + for &node in &[a, b] { + let nu = node as usize; + let adj_len = self.adj(nu).len(); + for adj_i in 0..adj_len { + let (edge_idx, neighbor) = self.adj(nu)[adj_i]; + let root_n = self.find(neighbor) as usize; + if root_n == new_root { + continue; + } + + let ft = self.fusible_time( + new_root, + root_n, + self.edges[edge_idx].weight, + current_time, + ); + if ft.is_finite() { + self.growth_events + .push(Reverse((ft.to_bits(), edge_idx, node, neighbor))); + } + } + } + } + } + + /// Build a spanning forest and peel to extract the correction. + /// Returns `(obs_mask, correction_edge_indices)`. + fn peel_correction_with_edges(&mut self) -> (u64, Vec) { + match self.config.peeling { + PeelingStrategy::PrimMst => self.peel_prim_mst(), + PeelingStrategy::Bfs => self.peel_bfs(), + } + } + + /// Prim's MST peeling: globally lightest spanning tree. Better accuracy. + fn peel_prim_mst(&mut self) -> (u64, Vec) { + let boundary = self.num_detectors; + + self.tree_parent.fill(None); + self.visited.fill(false); + self.visit_order.clear(); + self.peel_heap.clear(); + self.correction_edges.clear(); + + for seed in std::iter::once(boundary).chain(0..self.num_detectors) { + if self.visited[seed] { + continue; + } + self.visited[seed] = true; + self.visit_order.push(seed as u32); + + let adj_len = self.adj(seed).len(); + for adj_i in 0..adj_len { + let (edge_idx, neighbor) = self.adj(seed)[adj_i]; + if !self.visited[neighbor as usize] { + let w_bits = self.edges[edge_idx].weight.to_bits(); + self.peel_heap + .push(Reverse((w_bits, edge_idx, seed as u32, neighbor))); + } + } + + while let Some(Reverse((_w_bits, edge_idx, from, to))) = self.peel_heap.pop() { + let tu = to as usize; + if self.visited[tu] { + continue; + } + let from_root = self.find(from); + let to_root = self.find(to); + if from_root != to_root { + continue; + } + self.visited[tu] = true; + self.tree_parent[tu] = Some((from, edge_idx)); + self.visit_order.push(to); + + let adj_len = self.adj(tu).len(); + for adj_i in 0..adj_len { + let (e_idx, nbr) = self.adj(tu)[adj_i]; + if !self.visited[nbr as usize] { + let w_bits = self.edges[e_idx].weight.to_bits(); + self.peel_heap.push(Reverse((w_bits, e_idx, to, nbr))); + } + } + } + } + + // Peel: process in reverse visit order (leaves first). + self.subtree_parity.fill(false); + self.subtree_parity[..self.num_detectors] + .copy_from_slice(&self.is_defect[..self.num_detectors]); + + let mut obs_mask = 0u64; + + for i in (0..self.visit_order.len()).rev() { + let v = self.visit_order[i]; + if let Some((parent, edge_idx)) = self.tree_parent[v as usize] { + if self.subtree_parity[v as usize] { + obs_mask ^= self.edges[edge_idx].obs_mask; + self.correction_edges.push(edge_idx); + } + self.subtree_parity[parent as usize] ^= self.subtree_parity[v as usize]; + } + } + + (obs_mask, self.correction_edges.clone()) + } + + /// BFS peeling: simpler, faster (no heap), slightly less accurate. + fn peel_bfs(&mut self) -> (u64, Vec) { + let boundary = self.num_detectors; + + self.tree_parent.fill(None); + self.visited.fill(false); + self.visit_order.clear(); + self.correction_edges.clear(); + + for seed in std::iter::once(boundary).chain(0..self.num_detectors) { + if self.visited[seed] { + continue; + } + self.visited[seed] = true; + self.visit_order.push(seed as u32); + + let mut queue_start = self.visit_order.len() - 1; + while queue_start < self.visit_order.len() { + let v = self.visit_order[queue_start] as usize; + queue_start += 1; + + let adj_len = self.adj(v).len(); + for adj_i in 0..adj_len { + let (edge_idx, neighbor) = self.adj(v)[adj_i]; + let nu = neighbor as usize; + if self.visited[nu] { + continue; + } + let v_root = self.find(v as u32); + let n_root = self.find(neighbor); + if v_root != n_root { + continue; + } + self.visited[nu] = true; + self.tree_parent[nu] = Some((v as u32, edge_idx)); + self.visit_order.push(neighbor); + } + } + } + + self.subtree_parity.fill(false); + self.subtree_parity[..self.num_detectors] + .copy_from_slice(&self.is_defect[..self.num_detectors]); + + let mut obs_mask = 0u64; + for i in (0..self.visit_order.len()).rev() { + let v = self.visit_order[i]; + if let Some((parent, edge_idx)) = self.tree_parent[v as usize] { + if self.subtree_parity[v as usize] { + obs_mask ^= self.edges[edge_idx].obs_mask; + self.correction_edges.push(edge_idx); + } + self.subtree_parity[parent as usize] ^= self.subtree_parity[v as usize]; + } + } + + (obs_mask, self.correction_edges.clone()) + } + + /// Peel correction, returning only the observable mask. + fn peel_correction(&mut self) -> u64 { + self.peel_correction_with_edges().0 + } + + /// Number of edges in the matching graph. + #[must_use] + pub fn num_edges(&self) -> usize { + self.edges.len() + } + + /// Number of detectors. + #[must_use] + pub fn num_detectors(&self) -> usize { + self.num_detectors + } + + /// Get the observable mask for an edge. + #[must_use] + pub fn edge_obs_mask(&self, edge_idx: usize) -> u64 { + self.edges.get(edge_idx).map_or(0, |e| e.obs_mask) + } + + /// Get node1 of an edge. + #[must_use] + pub fn edge_node1(&self, edge_idx: usize) -> u32 { + self.edges.get(edge_idx).map_or(0, |e| e.node1) + } + + /// Get node2 of an edge (boundary = `num_detectors`). + #[must_use] + pub fn edge_node2(&self, edge_idx: usize) -> u32 { + self.edges.get(edge_idx).map_or(0, |e| e.node2) + } + + /// Get the weight of an edge (log-likelihood ratio). + #[must_use] + pub fn edge_weight(&self, edge_idx: usize) -> f64 { + self.edges.get(edge_idx).map_or(0.0, |e| e.weight) + } + + /// Decode with full UF (no predecoder) and return matched edges. + /// Used by windowed decoder which needs complete edge tracking. + pub fn decode_full_matching( + &mut self, + syndrome: &[u8], + ) -> Result<(u64, Vec), DecoderError> { + self.reset(); + for (i, &v) in syndrome.iter().enumerate() { + if v != 0 && i < self.num_detectors { + self.parity[i] = true; + self.is_defect[i] = true; + } + } + self.grow_clusters(); + Ok(self.peel_correction_with_edges()) + } + + // === UIUF support methods === + + /// Run syndrome validation (growth phase only, no peeling). + /// + /// After calling this, the internal cluster state reflects which nodes + /// have been merged. Use `edge_in_cluster()` to query which edges are + /// covered by clusters. + pub fn syndrome_validate(&mut self, syndrome: &[u8]) { + self.reset(); + for (i, &v) in syndrome.iter().enumerate() { + if v != 0 && i < self.num_detectors { + self.parity[i] = true; + self.is_defect[i] = true; + } + } + self.grow_clusters(); + } + + /// Check if an edge's two endpoints are in the same cluster. + /// + /// Call after `syndrome_validate()`. Returns true if the edge is + /// "covered" by a cluster (both endpoints merged into one component). + pub fn edge_in_cluster(&mut self, edge_idx: usize) -> bool { + if edge_idx >= self.edges.len() { + return false; + } + let n1 = self.edges[edge_idx].node1; + let n2 = self.edges[edge_idx].node2; + let root_a = self.find(n1); + let root_b = self.find(n2); + root_a == root_b + } + + /// Decode with pre-seeded erasure edges. + /// + /// Erasure edges are pre-merged into clusters before growth begins. + /// This is used by UIUF Phase 3 after the intersection step identifies + /// likely Y errors as erasures. + pub fn decode_with_erasures(&mut self, syndrome: &[u8], erasure_edges: &[usize]) -> u64 { + self.reset(); + for (i, &v) in syndrome.iter().enumerate() { + if v != 0 && i < self.num_detectors { + self.parity[i] = true; + self.is_defect[i] = true; + } + } + + // Pre-merge erasure edges before growth. + for &edge_idx in erasure_edges { + if edge_idx < self.edges.len() { + let n1 = self.edges[edge_idx].node1; + let n2 = self.edges[edge_idx].node2; + self.union(n1, n2); + } + } + + self.grow_clusters(); + self.peel_correction() + } +} + +// === Trait implementations === + +impl pecos_decoder_core::ObservableDecoder for UfDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + Ok(self.decode_syndrome(syndrome)) + } +} + +impl pecos_decoder_core::correlated_decoder::MatchingDecoder for UfDecoder { + fn decode_with_matching(&mut self, syndrome: &[u8]) -> Result<(u64, Vec), DecoderError> { + // Count defects for predecoder. + let num_defects = syndrome + .iter() + .take(self.num_detectors) + .filter(|&&v| v != 0) + .count() as u32; + + if num_defects == 0 { + return Ok((0, Vec::new())); + } + + // Cluster predecoder (if enabled). Skipped in windowed mode + // because windowed decoding needs complete edge tracking. + if self.config.predecoder + && let Some(obs) = self.predecode_clusters(syndrome) { + return Ok((obs, Vec::new())); + } + + // Full decode path. + self.reset(); + for (i, &v) in syndrome.iter().enumerate() { + if v != 0 && i < self.num_detectors { + self.parity[i] = true; + self.is_defect[i] = true; + } + } + self.grow_clusters(); + Ok(self.peel_correction_with_edges()) + } + + fn decode_with_weights( + &mut self, + syndrome: &[u8], + weights: &[f64], + ) -> Result<(u64, Vec), DecoderError> { + // Temporarily swap in the new weights + self.weight_swap.clear(); + for (i, &w) in weights.iter().enumerate() { + if i < self.edges.len() { + self.weight_swap.push((i, self.edges[i].weight)); + self.edges[i].weight = w; + } + } + + // Note: CSR adjacency sort order is fixed at construction. + // The weight swap affects growth event ordering but not correctness. + let result = self.decode_with_matching(syndrome); + + // Restore original weights + for &(i, w) in &self.weight_swap { + self.edges[i].weight = w; + } + + result + } + + fn num_edges(&self) -> usize { + self.edges.len() + } +} + +impl pecos_decoder_core::correlated_decoder::EdgeTrackingDecoder for UfDecoder { + fn edge_node1(&self, edge_idx: usize) -> u32 { + self.edges.get(edge_idx).map_or(0, |e| e.node1) + } + + fn edge_node2(&self, edge_idx: usize) -> u32 { + self.edges.get(edge_idx).map_or(0, |e| e.node2) + } + + fn edge_weight(&self, edge_idx: usize) -> f64 { + self.edges.get(edge_idx).map_or(0.0, |e| e.weight) + } + + fn edge_obs_mask(&self, edge_idx: usize) -> u64 { + self.edges.get(edge_idx).map_or(0, |e| e.obs_mask) + } + + fn num_detectors(&self) -> usize { + self.num_detectors + } +} + +impl pecos_decoder_core::erasure::ObservableErasureDecoder for UfDecoder { + fn decode_with_erasures( + &mut self, + syndrome: &[u8], + erasure_edges: &[usize], + ) -> Result { + if erasure_edges.is_empty() { + // Use MatchingDecoder path directly. + use pecos_decoder_core::correlated_decoder::MatchingDecoder; + let (obs, _) = self.decode_with_matching(syndrome)?; + return Ok(obs); + } + + // Set erased edges to weight=0 (certain error), decode, restore. + let mut modified_weights = Vec::with_capacity(self.edges.len()); + for (i, e) in self.edges.iter().enumerate() { + if erasure_edges.contains(&i) { + modified_weights.push(0.0); + } else { + modified_weights.push(e.weight); + } + } + + use pecos_decoder_core::correlated_decoder::MatchingDecoder; + let (obs, _) = self.decode_with_weights(syndrome, &modified_weights)?; + Ok(obs) + } +} + +#[cfg(test)] +mod tests { + use super::*; + + const SIMPLE_DEM: &str = "\ +error(0.1) D0 D1 L0 +error(0.1) D1 +"; + + const SURFACE_LIKE_DEM: &str = "\ +error(0.01) D0 D1 L0 +error(0.01) D1 D2 +error(0.01) D2 +error(0.01) D0 +"; + + #[test] + fn test_no_errors() { + let mut dec = UfDecoder::from_dem(SIMPLE_DEM, UfDecoderConfig::default()).unwrap(); + assert_eq!(dec.decode_syndrome(&[0, 0]), 0); + } + + #[test] + fn test_single_error() { + let mut dec = UfDecoder::from_dem(SIMPLE_DEM, UfDecoderConfig::default()).unwrap(); + // D0 and D1 both triggered -> edge D0-D1 (carries L0) + assert_eq!(dec.decode_syndrome(&[1, 1]), 1); + } + + #[test] + fn test_boundary_error() { + let mut dec = UfDecoder::from_dem(SIMPLE_DEM, UfDecoderConfig::default()).unwrap(); + // Only D1 triggered -> boundary edge (no observable) + assert_eq!(dec.decode_syndrome(&[0, 1]), 0); + } + + #[test] + fn test_multiple_shots() { + let mut dec = UfDecoder::from_dem(SIMPLE_DEM, UfDecoderConfig::default()).unwrap(); + for _ in 0..20 { + let _ = dec.decode_syndrome(&[1, 1]); + let _ = dec.decode_syndrome(&[0, 1]); + let _ = dec.decode_syndrome(&[0, 0]); + } + } + + #[test] + fn test_surface_like() { + let mut dec = UfDecoder::from_dem(SURFACE_LIKE_DEM, UfDecoderConfig::default()).unwrap(); + // D0 triggered -> boundary edge (no observable) + assert_eq!(dec.decode_syndrome(&[1, 0, 0]), 0); + // D0 and D1 -> edge D0-D1 (L0) + assert_eq!(dec.decode_syndrome(&[1, 1, 0]), 1); + } + + #[test] + fn test_observable_decoder_trait() { + use pecos_decoder_core::ObservableDecoder; + let mut dec = UfDecoder::from_dem(SIMPLE_DEM, UfDecoderConfig::default()).unwrap(); + let mask = dec.decode_to_observables(&[1, 1]).unwrap(); + assert_eq!(mask, 1); + } + + #[test] + fn test_matching_decoder_trait() { + use pecos_decoder_core::correlated_decoder::MatchingDecoder; + let mut dec = UfDecoder::from_dem(SIMPLE_DEM, UfDecoderConfig::default()).unwrap(); + let (mask, _edges) = dec.decode_with_matching(&[1, 1]).unwrap(); + assert_eq!(mask, 1); + // Note: predecoder may return empty edges for simple cases. + } + + /// Distance-3 repetition code: 3 data qubits, 2 detectors, 2 rounds. + /// Tests a more realistic graph structure with time-like edges. + const REP_CODE_D3_DEM: &str = "\ +error(0.01) D0 D1 +error(0.01) D0 L0 +error(0.01) D1 +error(0.001) D0 D2 +error(0.001) D1 D3 +error(0.01) D2 D3 +error(0.01) D2 L0 +error(0.01) D3 +"; + + #[test] + fn test_rep_code_d3() { + let mut dec = UfDecoder::from_dem(REP_CODE_D3_DEM, UfDecoderConfig::default()).unwrap(); + assert_eq!(dec.num_edges(), 8); + assert_eq!(dec.num_detectors(), 4); + + // No defects + assert_eq!(dec.decode_syndrome(&[0, 0, 0, 0]), 0); + + // Single data error in round 1: D0 and D1 both fire + assert_eq!(dec.decode_syndrome(&[1, 1, 0, 0]), 0); + + // Boundary error: only D0 + assert_eq!(dec.decode_syndrome(&[1, 0, 0, 0]), 1); // L0 + + // Single boundary error round 2: only D2 + assert_eq!(dec.decode_syndrome(&[0, 0, 1, 0]), 1); // L0 + } + + #[test] + fn test_stress_reuse() { + // Verify buffers are correctly reused over many shots + let mut dec = UfDecoder::from_dem(REP_CODE_D3_DEM, UfDecoderConfig::default()).unwrap(); + let syndromes: &[&[u8]] = &[ + &[0, 0, 0, 0], + &[1, 1, 0, 0], + &[1, 0, 0, 0], + &[0, 1, 0, 0], + &[0, 0, 1, 1], + &[1, 0, 1, 0], + ]; + for _ in 0..1000 { + for syn in syndromes { + let _ = dec.decode_syndrome(syn); + } + } + } +} diff --git a/crates/pecos-uf-decoder/src/lib.rs b/crates/pecos-uf-decoder/src/lib.rs new file mode 100644 index 000000000..180bccf56 --- /dev/null +++ b/crates/pecos-uf-decoder/src/lib.rs @@ -0,0 +1,51 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Fast syndrome-graph Union-Find decoder. +//! +//! Purpose-built for surface codes and other QEC codes with matching-graph +//! structure. Works on the syndrome graph (not the Tanner graph), where nodes +//! are detectors and edges are error mechanisms. +//! +//! Design goals: +//! - Zero per-shot allocation (reusable flat arrays) +//! - No locks, no Arc, no hash sets (unlike MWPF's UF) +//! - Bounded worst-case latency +//! - Implements `ObservableDecoder` and `MatchingDecoder` for composability +//! with `TwoPassDecoder` (correlated decoding) + +#![allow( + clippy::cast_possible_truncation, + clippy::cast_precision_loss, + clippy::cast_sign_loss +)] + +pub mod astar; +pub mod bp_uf; +pub mod css_decoder; +pub mod decoder; +pub mod mini_bp; + +pub mod windowed; + +// Note: belief_matching (BP → PyMatching MWPM) lives in the Python bindings +// (fault_tolerance_bindings.rs) since it requires pecos-pymatching which is +// a C++ FFI crate. This crate stays pure Rust. + +pub use astar::{AStarConfig, AStarDecoder}; +pub use bp_uf::{BpSchedule, BpUfConfig, BpUfDecoder}; +pub use css_decoder::{CssUfDecoder, QubitEdgeMapping}; +pub use decoder::{UfDecoder, UfDecoderConfig}; +pub use windowed::{ + BeamSearchConfig, BeamSearchWindowedDecoder, OverlappingWindowedDecoder, + SandwichWindowedDecoder, StreamingWindowedDecoder, WindowedConfig, WindowedDecoder, +}; diff --git a/crates/pecos-uf-decoder/src/mini_bp.rs b/crates/pecos-uf-decoder/src/mini_bp.rs new file mode 100644 index 000000000..325d5a7cf --- /dev/null +++ b/crates/pecos-uf-decoder/src/mini_bp.rs @@ -0,0 +1,501 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Minimal min-sum belief propagation for BP+UF hybrid decoding. +//! +//! Runs a few iterations of min-sum BP on the check matrix (Tanner graph) +//! to produce per-mechanism soft reliability scores. These scores are then +//! used to adjust UF edge weights for better accuracy. +//! +//! This is intentionally minimal -- no normalization, no scheduling tricks. +//! Just enough BP to extract useful soft information for UF. + +use pecos_decoder_core::dem::DemCheckMatrix; + +/// Pre-computed sparse structure for BP message passing. +/// Build once at construction time, reuse across shots. +/// Uses CSR-style flat arrays for cache-friendly iteration. +pub struct BpGraph { + pub num_checks: usize, + pub num_vars: usize, + pub prior_llr: Vec, + /// CSR for checks: flat data of (`var_idx`, `msg_array_idx`). + check_data: Vec<(u32, u32)>, + /// CSR offsets for checks: `check_offset`[c]..`check_offset`[c+1]. + check_offset: Vec, + /// CSR for vars: flat data of (`check_idx`, `msg_array_idx`). + var_data: Vec<(u32, u32)>, + /// CSR offsets for vars: `var_offset`[v]..`var_offset`[v+1]. + var_offset: Vec, + /// Total number of edges in the Tanner graph. + pub total_edges: usize, +} + +impl BpGraph { + /// Get check entries (CSR slice). + #[inline] + #[must_use] + pub fn check_entries(&self, c: usize) -> &[(u32, u32)] { + let s = self.check_offset[c] as usize; + let e = self.check_offset[c + 1] as usize; + &self.check_data[s..e] + } + + /// Get var entries (CSR slice). + #[inline] + fn var_entries(&self, v: usize) -> &[(u32, u32)] { + let s = self.var_offset[v] as usize; + let e = self.var_offset[v + 1] as usize; + &self.var_data[s..e] + } + + /// Build from a `DemCheckMatrix`. + #[must_use] + pub fn from_dcm(dcm: &DemCheckMatrix) -> Self { + let num_checks = dcm.num_detectors; + let num_vars = dcm.num_mechanisms; + + let prior_llr: Vec = dcm + .error_priors + .iter() + .map(|&p| { + if p <= 0.0 { + 30.0 + } else if p >= 1.0 { + -30.0 + } else { + ((1.0 - p) / p).ln() + } + }) + .collect(); + + // Build temporary adjacency then flatten to CSR. + let mut temp_check: Vec> = vec![Vec::new(); num_checks]; + let mut temp_var: Vec> = vec![Vec::new(); num_vars]; + let mut msg_idx: u32 = 0; + + for c in 0..num_checks { + for v in 0..num_vars { + if dcm.check_matrix[[c, v]] != 0 { + temp_check[c].push((v as u32, msg_idx)); + temp_var[v].push((c as u32, msg_idx)); + msg_idx += 1; + } + } + } + + // Flatten check entries. + let mut check_data = Vec::new(); + let mut check_offset = Vec::with_capacity(num_checks + 1); + for entries in &temp_check { + check_offset.push(check_data.len() as u32); + check_data.extend_from_slice(entries); + } + check_offset.push(check_data.len() as u32); + + // Flatten var entries. + let mut var_data = Vec::new(); + let mut var_offset = Vec::with_capacity(num_vars + 1); + for entries in &temp_var { + var_offset.push(var_data.len() as u32); + var_data.extend_from_slice(entries); + } + var_offset.push(var_data.len() as u32); + + Self { + num_checks, + num_vars, + prior_llr, + check_data, + check_offset, + var_data, + var_offset, + total_edges: msg_idx as usize, + } + } +} + +/// Run min-sum BP on a pre-computed graph and return posterior LLRs per mechanism. +/// +/// - `graph`: pre-computed sparse BP graph +/// - `syndrome`: detection events (1 = triggered) +/// - `num_iterations`: number of BP iterations +/// - `min_sum_scale`: scaling factor for min-sum messages (0.625 is standard) +/// - `serial`: if true, use serial schedule (better convergence, slower) +/// - `c_to_v`, `v_to_c`: reusable message buffers (must be `graph.total_edges` long) +/// - `posterior`: output buffer (must be `graph.num_vars` long) +pub fn min_sum_bp_into( + graph: &BpGraph, + syndrome: &[u8], + num_iterations: usize, + min_sum_scale: f64, + serial: bool, + c_to_v: &mut [f64], + v_to_c: &mut [f64], + posterior: &mut Vec, +) { + let num_checks = graph.num_checks; + let num_vars = graph.num_vars; + + // Initialize v→c with priors. + for v in 0..num_vars { + for &(_c, idx) in graph.var_entries(v) { + v_to_c[idx as usize] = graph.prior_llr[v]; + } + } + + // Pre-compute syndrome signs (avoid branch in inner loop). + let mut syn_sign = vec![1.0f64; num_checks]; + for (c, sign) in syn_sign.iter_mut().enumerate() { + if c < syndrome.len() && syndrome[c] != 0 { + *sign = -1.0; + } + } + + let damp = 0.25; + + // EWA posterior accumulator. + let ewa_weight = 0.3; + let mut ewa_posterior = vec![0.0f64; num_vars]; + ewa_posterior.copy_from_slice(&graph.prior_llr); + + // EWAInit: run BP multiple times, using EWA of previous posteriors + // as the prior for the next run. This finds better fixed points. + let outer_iterations = if num_iterations >= 6 { 2 } else { 1 }; + let inner_iterations = if outer_iterations > 1 { + num_iterations / outer_iterations + } else { + num_iterations + }; + + for _outer in 0..outer_iterations { + // Re-initialize v→c with current EWA posteriors as priors. + if _outer > 0 { + for v in 0..num_vars { + for &(_c, idx) in graph.var_entries(v) { + v_to_c[idx as usize] = ewa_posterior[v]; + } + } + c_to_v.fill(0.0); + } + + for iter in 0..inner_iterations { + for c in 0..num_checks { + let entries = graph.check_entries(c); + if entries.len() < 2 { + continue; + } + + // Check-to-variable (normalized min-sum). + let mut total_sign = syn_sign[c]; + let mut min1 = f64::INFINITY; + let mut min2 = f64::INFINITY; + let mut min1_pos = usize::MAX; + + for (pos, &(_v, idx)) in entries.iter().enumerate() { + let msg = v_to_c[idx as usize]; + if msg < 0.0 { + total_sign = -total_sign; + } + let abs_msg = msg.abs(); + if abs_msg < min1 { + min2 = min1; + min1 = abs_msg; + min1_pos = pos; + } else if abs_msg < min2 { + min2 = abs_msg; + } + } + + for (pos, &(_v, idx)) in entries.iter().enumerate() { + let msg_v = v_to_c[idx as usize]; + let sign_without_v = total_sign.copysign(total_sign * msg_v); + let min_without_v = if pos == min1_pos { min2 } else { min1 }; + c_to_v[idx as usize] = sign_without_v * min_without_v * min_sum_scale; + } + + if serial { + // Serial: immediately update v→c for connected variables. + for &(v_idx, _) in entries { + let v = v_idx as usize; + let gamma = damp; + let v_entries = graph.var_entries(v); + let total: f64 = v_entries + .iter() + .map(|&(_c2, idx2)| c_to_v[idx2 as usize]) + .sum(); + for &(_c2, idx2) in v_entries { + let new_msg = graph.prior_llr[v] + total - c_to_v[idx2 as usize]; + v_to_c[idx2 as usize] = + (1.0 - gamma) * new_msg + gamma * v_to_c[idx2 as usize]; + } + } + } + } + + if !serial { + // Flooding: batch update all variables after all checks. + for v in 0..num_vars { + let gamma = damp; + let entries = graph.var_entries(v); + let total: f64 = entries.iter().map(|&(_c, idx)| c_to_v[idx as usize]).sum(); + for &(_c, idx) in entries { + let new_msg = graph.prior_llr[v] + total - c_to_v[idx as usize]; + v_to_c[idx as usize] = + (1.0 - gamma) * new_msg + gamma * v_to_c[idx as usize]; + } + } + } + + // EWA: blend current iteration's posterior into the running average. + let w = if iter == 0 && _outer == 0 { + 1.0 + } else { + ewa_weight + }; + for v in 0..num_vars { + let cur_posterior = graph.prior_llr[v] + + graph + .var_entries(v) + .iter() + .map(|&(_c, idx)| c_to_v[idx as usize]) + .sum::(); + ewa_posterior[v] = (1.0 - w) * ewa_posterior[v] + w * cur_posterior; + } + } // end inner iteration loop + } // end outer EWAInit loop + + // Use EWA-averaged posteriors (smoothed across all iterations). + posterior.clear(); + posterior.extend_from_slice(&ewa_posterior); + // Also include final iteration's raw posterior for variables where + // EWA and raw agree in sign (reinforcement). + for v in 0..num_vars { + let raw = graph.prior_llr[v] + + graph + .var_entries(v) + .iter() + .map(|&(_c, idx)| c_to_v[idx as usize]) + .sum::(); + // If EWA and raw agree, use the one with larger magnitude (more confident). + if (posterior[v] > 0.0) == (raw > 0.0) + && raw.abs() > posterior[v].abs() { + posterior[v] = raw; + } + // If they disagree, keep EWA (it's more stable). + } +} + +/// BP on the matching graph (Hack et al. 2026 style). +/// +/// Instead of running BP on the Tanner graph (check matrix), run on the +/// matching graph where: +/// - Variables = matching graph edges (is this edge in the correction?) +/// - Factors = detector nodes (parity constraint from syndrome) +/// +/// The matching graph has simpler topology (no hyperedges, more tree-like), +/// so BP converges better. Returns per-edge posterior LLRs. +#[must_use] +pub fn matching_graph_bp( + graph: &pecos_decoder_core::dem::DemMatchingGraph, + syndrome: &[u8], + num_iterations: usize, + min_sum_scale: f64, +) -> Vec { + let num_nodes = graph.num_detectors + 1; // +1 for boundary + let num_edges = graph.edges.len(); + let boundary = graph.num_detectors; + + // Prior LLRs for each edge. + let prior_llr: Vec = graph.edges.iter().map(|e| e.weight).collect(); + + // Build adjacency: for each node, list of incident edges. + let mut node_edges: Vec> = vec![Vec::new(); num_nodes]; + for (idx, edge) in graph.edges.iter().enumerate() { + node_edges[edge.node1 as usize].push(idx); + if let Some(n2) = edge.node2 { + node_edges[n2 as usize].push(idx); + } else { + node_edges[boundary].push(idx); + } + } + + // Messages: node-to-edge and edge-to-node. + // For each (node, edge) pair, store the message index. + let mut msg_idx = 0usize; + let mut node_msg: Vec> = vec![Vec::new(); num_nodes]; // node -> [(edge_idx, msg_idx)] + let mut edge_msg: Vec> = vec![Vec::new(); num_edges]; // edge -> [(node_idx, msg_idx)] + for (node, edges) in node_edges.iter().enumerate() { + for &edge_idx in edges { + node_msg[node].push((edge_idx, msg_idx)); + edge_msg[edge_idx].push((node, msg_idx)); + msg_idx += 1; + } + } + + let total_msgs = msg_idx; + let mut n_to_e = vec![0.0f64; total_msgs]; // node→edge messages + let mut e_to_n = vec![0.0f64; total_msgs]; // edge→node messages + + // Initialize edge→node with prior LLRs. + for (edge_idx, entries) in edge_msg.iter().enumerate() { + for &(_, midx) in entries { + e_to_n[midx] = prior_llr[edge_idx]; + } + } + + // Syndrome sign. + let syn_sign: Vec = (0..num_nodes) + .map(|n| { + if n < syndrome.len() && syndrome[n] != 0 { + -1.0 + } else if n == boundary { + 1.0 + } + // boundary always even + else { + 1.0 + } + }) + .collect(); + + let damp = 0.25; + + for _iter in 0..num_iterations { + // Node-to-edge (check-to-variable): min-sum update. + // Same as Tanner graph BP but on matching graph nodes. + for node in 0..num_nodes { + let entries = &node_msg[node]; + if entries.len() < 2 { + continue; + } + + let mut total_sign = syn_sign[node]; + let mut min1 = f64::INFINITY; + let mut min2 = f64::INFINITY; + let mut min1_pos = usize::MAX; + + for (pos, &(_, midx)) in entries.iter().enumerate() { + let msg = e_to_n[midx]; + if msg < 0.0 { + total_sign = -total_sign; + } + let abs_msg = msg.abs(); + if abs_msg < min1 { + min2 = min1; + min1 = abs_msg; + min1_pos = pos; + } else if abs_msg < min2 { + min2 = abs_msg; + } + } + + for (pos, &(_, midx)) in entries.iter().enumerate() { + let msg_v = e_to_n[midx]; + let sign_without = total_sign.copysign(total_sign * msg_v); + let min_without = if pos == min1_pos { min2 } else { min1 }; + n_to_e[midx] = sign_without * min_without * min_sum_scale; + } + } + + // Edge-to-node (variable-to-check): sum incoming + prior. + for (edge_idx, entries) in edge_msg.iter().enumerate() { + let total: f64 = entries.iter().map(|&(_, midx)| n_to_e[midx]).sum(); + for &(_, midx) in entries { + let new_msg = prior_llr[edge_idx] + total - n_to_e[midx]; + e_to_n[midx] = (1.0 - damp) * new_msg + damp * e_to_n[midx]; + } + } + } + + // Posterior: prior + sum of all node→edge messages. + let mut posterior = prior_llr; + for (edge_idx, entries) in edge_msg.iter().enumerate() { + for &(_, midx) in entries { + posterior[edge_idx] += n_to_e[midx]; + } + } + + posterior +} + +/// Convenience wrapper: build graph, run BP, return posteriors. +#[must_use] +pub fn min_sum_bp( + dcm: &DemCheckMatrix, + syndrome: &[u8], + num_iterations: usize, + min_sum_scale: f64, +) -> Vec { + let graph = BpGraph::from_dcm(dcm); + let mut c_to_v = vec![0.0f64; graph.total_edges]; + let mut v_to_c = vec![0.0f64; graph.total_edges]; + let mut posterior = Vec::with_capacity(graph.num_vars); + min_sum_bp_into( + &graph, + syndrome, + num_iterations, + min_sum_scale, + false, + &mut c_to_v, + &mut v_to_c, + &mut posterior, + ); + posterior +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_mini_bp_no_syndrome() { + // Simple 2-check, 3-mechanism DEM. + let dem_str = "\ +error(0.1) D0 D1 L0 +error(0.1) D1 +error(0.05) D0 +"; + let dcm = DemCheckMatrix::from_dem_str(dem_str).unwrap(); + let syndrome = vec![0u8; dcm.num_detectors]; + + let posterior = min_sum_bp(&dcm, &syndrome, 5, 0.625); + assert_eq!(posterior.len(), dcm.num_mechanisms); + + // With no syndrome, all posteriors should be positive (no error likely). + for &llr in &posterior { + assert!(llr > 0.0, "Expected positive LLR for no-syndrome case"); + } + } + + #[test] + fn test_mini_bp_with_syndrome() { + let dem_str = "\ +error(0.1) D0 D1 L0 +error(0.1) D1 +error(0.05) D0 +"; + let dcm = DemCheckMatrix::from_dem_str(dem_str).unwrap(); + // D0 and D1 both triggered -> mechanism 0 (D0-D1) is likely. + let syndrome = vec![1, 1]; + + let posterior = min_sum_bp(&dcm, &syndrome, 5, 0.625); + assert_eq!(posterior.len(), dcm.num_mechanisms); + + // Mechanism 0 (D0 D1) should have lower (more negative) LLR + // since both its checks are triggered. + assert!( + posterior[0] < posterior[2], + "Mechanism touching both triggered checks should be more likely" + ); + } +} diff --git a/crates/pecos-uf-decoder/src/windowed.rs b/crates/pecos-uf-decoder/src/windowed.rs new file mode 100644 index 000000000..5aa130dd4 --- /dev/null +++ b/crates/pecos-uf-decoder/src/windowed.rs @@ -0,0 +1,1453 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Sliding-window decoder for real-time surface code decoding. +//! +//! Two modes: +//! +//! - **Non-overlapping (`buf=0`)**: sub-DEM per window, any inner decoder, +//! observable XOR across windows. Converges to ~1.03x penalty at large r +//! (matching Tan et al.). Inner decoder is pluggable via factory. +//! +//! - **Overlapping (`buf>0`)**: uses `UfDecoder` for edge tracking. Each +//! window is extended by buffer rounds for matching context. Only corrections +//! with both endpoints in the core region are committed. No artificial defect +//! injection — the buffer just provides graph context (Tan et al.). +//! +//! Reference: Tan et al., PRX Quantum 2023 (arXiv:2209.09219). + +use pecos_decoder_core::ObservableDecoder; +use pecos_decoder_core::correlated_decoder::EdgeTrackingDecoder; +use pecos_decoder_core::dem::DemMatchingGraph; +use pecos_decoder_core::errors::DecoderError; + +/// Configuration for the windowed decoder. +#[derive(Debug, Clone, Copy, Default)] +pub struct WindowedConfig { + /// Commit rounds per window (step size). 0 = auto (code distance). + pub step_size: usize, + /// Buffer rounds on each side of the core. 0 = non-overlapping. + /// Recommended: set equal to code distance for near-zero penalty. + pub buffer_size: usize, + /// Half-width of Type-2 seam windows in rounds. 0 = auto (step/2). + pub seam_half_width: usize, + /// Extend core by this many layers into the buffer on each side. + /// Committed edges can touch the extended core, capturing more + /// boundary corrections. 0 = strict core only (default). + pub core_extend: usize, + /// Maximum edge weight for Phase-1 commit. Only correction edges + /// with weight below this are committed (high-confidence corrections). + /// 0.0 = no threshold (commit all core edges, default). + pub commit_weight_max: f64, +} + +// ============================================================================= +// Non-overlapping windowed decoder (buf=0) +// ============================================================================= + +/// Pre-built window with a generic inner decoder. +struct PrebuiltWindow { + decoder: Box, + local_to_global: Vec, + num_local: usize, +} + +/// Non-overlapping windowed decoder. Any `ObservableDecoder` as inner decoder. +pub struct WindowedDecoder { + windows: Vec, +} + +impl WindowedDecoder { + /// Create from a DEM string with a decoder factory. + /// + /// # Errors + /// + /// Returns `DecoderError` if the DEM is malformed or the factory fails. + pub fn from_dem( + dem: &str, + config: WindowedConfig, + mut decoder_factory: F, + ) -> Result + where + F: FnMut(&str) -> Result, DecoderError>, + { + let (det_times, num_detectors, step_size, total_t) = parse_dem_params(dem, &config)?; + let mut windows = Vec::new(); + let mut t_start = 0.0f64; + + while t_start < total_t { + let is_last = t_start + 2.0 * step_size as f64 > total_t; + let t_end = if is_last { + total_t + 1.0 + } else { + t_start + step_size as f64 + }; + + let (local_to_global, window_dem) = + extract_window_dem(dem, &det_times, num_detectors, t_start, t_end); + + let num_local = local_to_global.len(); + if num_local > 0 && !window_dem.is_empty() { + let decoder = decoder_factory(&window_dem)?; + windows.push(PrebuiltWindow { + decoder, + local_to_global, + num_local, + }); + } + + t_start += step_size as f64; + } + + Ok(Self { windows }) + } + + /// Number of windows. + #[must_use] + pub fn num_windows(&self) -> usize { + self.windows.len() + } +} + +impl ObservableDecoder for WindowedDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + let mut obs_mask = 0u64; + for window in &mut self.windows { + let mut window_syn = vec![0u8; window.num_local]; + for (local_id, &global_id) in window.local_to_global.iter().enumerate() { + let gid = global_id as usize; + if gid < syndrome.len() { + window_syn[local_id] = syndrome[gid]; + } + } + obs_mask ^= window.decoder.decode_to_observables(&window_syn)?; + } + Ok(obs_mask) + } +} + +// ============================================================================= +// Overlapping windowed decoder (buf>0, Tan et al.) +// ============================================================================= + +/// Pre-built overlapping window with an edge-tracking inner decoder. +struct OverlappingWindow { + decoder: D, + local_to_global: Vec, + /// Per local detector: true = core region, false = buffer. + is_core: Vec, + num_local: usize, +} + +/// Overlapping windowed decoder using any `EdgeTrackingDecoder` for edge tracking. +/// +/// Each window is extended by buffer rounds for matching context. +/// Only core corrections are committed; buffer corrections are discarded. +pub struct OverlappingWindowedDecoder { + windows: Vec>, +} + +impl OverlappingWindowedDecoder { + /// Create from a DEM string with a factory for the inner decoder. + /// + /// # Errors + /// + /// Returns `DecoderError` if the DEM is malformed or the factory fails. + pub fn from_dem( + dem: &str, + config: WindowedConfig, + mut factory: F, + ) -> Result + where + F: FnMut(&str) -> Result, + { + let (det_times, num_detectors, step_size, total_t) = parse_dem_params(dem, &config)?; + let buffer_size = config.buffer_size; + let mut windows = Vec::new(); + let mut t_start = 0.0f64; + + while t_start < total_t { + let is_last = t_start + 2.0 * step_size as f64 > total_t; + let t_core_end = if is_last { + total_t + 1.0 + } else { + t_start + step_size as f64 + }; + let t_win_start = (t_start - buffer_size as f64).max(0.0); + let t_win_end = if is_last { + total_t + 1.0 + } else { + t_core_end + buffer_size as f64 + }; + + let (local_to_global, window_dem) = + extract_window_dem(dem, &det_times, num_detectors, t_win_start, t_win_end); + + let ext = config.core_extend as f64; + let is_core: Vec = local_to_global + .iter() + .map(|&gid| { + let t = det_times[gid as usize]; + t >= (t_start - ext) && t < (t_core_end + ext) + }) + .collect(); + + let num_local = local_to_global.len(); + if num_local > 0 && !window_dem.is_empty() { + let decoder = factory(&window_dem)?; + windows.push(OverlappingWindow { + decoder, + local_to_global, + is_core, + num_local, + }); + } + + t_start += step_size as f64; + } + + Ok(Self { windows }) + } + + /// Number of windows. + #[must_use] + pub fn num_windows(&self) -> usize { + self.windows.len() + } +} + +impl ObservableDecoder for OverlappingWindowedDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + let mut obs_mask = 0u64; + + for window in &mut self.windows { + let mut window_syn = vec![0u8; window.num_local]; + for (local_id, &global_id) in window.local_to_global.iter().enumerate() { + let gid = global_id as usize; + if gid < syndrome.len() { + window_syn[local_id] = syndrome[gid]; + } + } + + // Use MatchingDecoder trait for edge tracking. + let (_, matched_edges) = window.decoder.decode_with_matching(&window_syn)?; + + let boundary = window.num_local as u32; + for &edge_idx in &matched_edges { + let n1 = window.decoder.edge_node1(edge_idx); + let n2 = window.decoder.edge_node2(edge_idx); + + let n1_core = n1 >= boundary + || ((n1 as usize) < window.is_core.len() && window.is_core[n1 as usize]); + let n2_core = n2 >= boundary + || ((n2 as usize) < window.is_core.len() && window.is_core[n2 as usize]); + + if n1_core && n2_core { + obs_mask ^= window.decoder.edge_obs_mask(edge_idx); + } + } + } + + Ok(obs_mask) + } +} + +// ============================================================================= +// Sandwich windowed decoder (Tan et al. two-phase) +// ============================================================================= + +/// Sandwich windowed decoder: two-phase decoding for reduced boundary penalty. +/// +/// Phase 1 (Type-1): Overlapping windows with core-only commit, same as +/// `OverlappingWindowedDecoder`. Independent, can run in parallel. +/// +/// Phase 2 (Type-2): Small seam windows at core boundaries decode the +/// residual syndrome left by Type-1. The residual is computed as +/// `original XOR correction_effect` where `correction_effect` tracks +/// which syndrome bits were flipped by Type-1's committed edges. +/// +/// This gives Type-2 bidirectional boundary information from both +/// flanking Type-1 windows, reducing the boundary penalty. +pub struct SandwichWindowedDecoder { + type1_windows: Vec>, + residual_decoder: Box, + num_detectors: usize, + commit_weight_max: f64, +} + +impl SandwichWindowedDecoder { + /// Create from a DEM string with factories for Phase-1 and Phase-2 decoders. + /// + /// # Errors + /// + /// Returns `DecoderError` if the DEM is malformed or factories fail. + pub fn from_dem( + dem: &str, + config: WindowedConfig, + mut phase1_factory: F1, + mut phase2_factory: F2, + ) -> Result + where + F1: FnMut(&str) -> Result, + F2: FnMut(&str) -> Result, DecoderError>, + { + let (det_times, num_detectors, step_size, total_t) = parse_dem_params(dem, &config)?; + let buffer_size = config.buffer_size; + + let mut type1_windows = Vec::new(); + let mut t_start = 0.0f64; + + while t_start < total_t { + let is_last = t_start + 2.0 * step_size as f64 > total_t; + let t_core_end = if is_last { + total_t + 1.0 + } else { + t_start + step_size as f64 + }; + let t_win_start = (t_start - buffer_size as f64).max(0.0); + let t_win_end = if is_last { + total_t + 1.0 + } else { + t_core_end + buffer_size as f64 + }; + + let (local_to_global, window_dem) = + extract_window_dem(dem, &det_times, num_detectors, t_win_start, t_win_end); + + let ext = config.core_extend as f64; + let is_core: Vec = local_to_global + .iter() + .map(|&gid| { + let t = det_times[gid as usize]; + t >= (t_start - ext) && t < (t_core_end + ext) + }) + .collect(); + + let num_local = local_to_global.len(); + if num_local > 0 && !window_dem.is_empty() { + let decoder = phase1_factory(&window_dem)?; + type1_windows.push(OverlappingWindow { + decoder, + local_to_global, + is_core, + num_local, + }); + } + + t_start += step_size as f64; + } + + let residual_decoder = phase2_factory(dem)?; + + Ok(Self { + type1_windows, + residual_decoder, + num_detectors, + commit_weight_max: config.commit_weight_max, + }) + } + + /// Number of Type-1 windows. + #[must_use] + pub fn num_windows(&self) -> usize { + self.type1_windows.len() + } + + /// Decode with parallel Phase-1 windows using rayon. + /// + /// Requires `D: Send` for thread safety. Phase-1 windows run on rayon's + /// thread pool; Phase-2 residual runs sequentially after. + pub fn decode_parallel(&mut self, syndrome: &[u8]) -> Result + where + D: Send, + { + use rayon::prelude::*; + + let commit_weight_max = self.commit_weight_max; + let num_detectors = self.num_detectors; + + // Phase 1: Decode Type-1 windows in parallel. + let window_results: Result, DecoderError> = self + .type1_windows + .par_iter_mut() + .map(|window| { + let mut window_syn = vec![0u8; window.num_local]; + for (local_id, &global_id) in window.local_to_global.iter().enumerate() { + let gid = global_id as usize; + if gid < syndrome.len() { + window_syn[local_id] = syndrome[gid]; + } + } + + let (_, matched_edges) = window.decoder.decode_with_matching(&window_syn)?; + + let mut obs = 0u64; + let mut corrections: Vec<(usize, u8)> = Vec::new(); + let boundary = window.num_local as u32; + + for &edge_idx in &matched_edges { + let n1 = window.decoder.edge_node1(edge_idx); + let n2 = window.decoder.edge_node2(edge_idx); + + let n1_core = n1 >= boundary + || ((n1 as usize) < window.is_core.len() && window.is_core[n1 as usize]); + let n2_core = n2 >= boundary + || ((n2 as usize) < window.is_core.len() && window.is_core[n2 as usize]); + + let weight_ok = commit_weight_max <= 0.0 + || window.decoder.edge_weight(edge_idx) <= commit_weight_max; + + if n1_core && n2_core && weight_ok { + obs ^= window.decoder.edge_obs_mask(edge_idx); + if (n1 as usize) < window.num_local { + corrections.push((window.local_to_global[n1 as usize] as usize, 1)); + } + if (n2 as usize) < window.num_local { + corrections.push((window.local_to_global[n2 as usize] as usize, 1)); + } + } + } + + Ok((obs, corrections)) + }) + .collect(); + + // Merge results (XOR is order-independent). + let mut obs_mask = 0u64; + let mut correction_effect = vec![0u8; num_detectors]; + for (window_obs, corrections) in window_results? { + obs_mask ^= window_obs; + for (gid, bit) in corrections { + correction_effect[gid] ^= bit; + } + } + + // Phase 2: Residual decode (sequential). + let mut residual_syn = vec![0u8; num_detectors]; + for (i, &s) in syndrome.iter().enumerate() { + if i < num_detectors { + residual_syn[i] = s ^ correction_effect[i]; + } + } + obs_mask ^= self.residual_decoder.decode_to_observables(&residual_syn)?; + + Ok(obs_mask) + } +} + +impl ObservableDecoder for SandwichWindowedDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + let mut obs_mask = 0u64; + let mut correction_effect = vec![0u8; self.num_detectors]; + let commit_weight_max = self.commit_weight_max; + + // Phase 1: Decode Type-1 windows. + for window in &mut self.type1_windows { + let mut window_syn = vec![0u8; window.num_local]; + for (local_id, &global_id) in window.local_to_global.iter().enumerate() { + let gid = global_id as usize; + if gid < syndrome.len() { + window_syn[local_id] = syndrome[gid]; + } + } + + let (_, matched_edges) = window.decoder.decode_with_matching(&window_syn)?; + + let boundary = window.num_local as u32; + for &edge_idx in &matched_edges { + let n1 = window.decoder.edge_node1(edge_idx); + let n2 = window.decoder.edge_node2(edge_idx); + + let n1_core = n1 >= boundary + || ((n1 as usize) < window.is_core.len() && window.is_core[n1 as usize]); + let n2_core = n2 >= boundary + || ((n2 as usize) < window.is_core.len() && window.is_core[n2 as usize]); + + let weight_ok = commit_weight_max <= 0.0 + || window.decoder.edge_weight(edge_idx) <= commit_weight_max; + + if n1_core && n2_core && weight_ok { + obs_mask ^= window.decoder.edge_obs_mask(edge_idx); + + if (n1 as usize) < window.num_local { + let gid = window.local_to_global[n1 as usize] as usize; + correction_effect[gid] ^= 1; + } + if (n2 as usize) < window.num_local { + let gid = window.local_to_global[n2 as usize] as usize; + correction_effect[gid] ^= 1; + } + } + } + } + + // Phase 2: Decode residual syndrome on the full graph. + let mut residual_syn = vec![0u8; self.num_detectors]; + for (i, &s) in syndrome.iter().enumerate() { + if i < self.num_detectors { + residual_syn[i] = s ^ correction_effect[i]; + } + } + obs_mask ^= self.residual_decoder.decode_to_observables(&residual_syn)?; + + Ok(obs_mask) + } +} + +// ============================================================================= +// Shared helpers +// ============================================================================= + +/// Parse DEM parameters for windowing. +fn parse_dem_params( + dem: &str, + config: &WindowedConfig, +) -> Result<(Vec, usize, usize, f64), DecoderError> { + let graph = DemMatchingGraph::from_dem_str(dem)?; + let num_detectors = graph.num_detectors; + + let mut det_times = vec![0.0f64; num_detectors]; + let mut max_time = 0.0f64; + for (i, coord) in graph.detector_coords.iter().enumerate() { + if let Some(c) = coord { + let t = c.get(2).copied().unwrap_or(0.0); + if i < det_times.len() { + det_times[i] = t; + } + if t > max_time { + max_time = t; + } + } + } + + let num_rounds = (max_time + 1.0) as usize; + let num_stab = if num_rounds > 0 { + num_detectors / num_rounds + } else { + num_detectors + }; + let d_est = ((num_stab as f64).sqrt().ceil() as usize).max(3); + let step_size = if config.step_size > 0 { + config.step_size + } else { + d_est + }; + let total_t = num_rounds as f64; + + Ok((det_times, num_detectors, step_size, total_t)) +} + +/// Extract a window sub-DEM by filtering the original DEM text. +/// +/// Detectors in `[t_start, t_end)` are included and remapped to local IDs. +/// Detectors outside the window are dropped from error mechanisms, creating +/// implicit boundary edges. +fn extract_window_dem( + dem: &str, + det_times: &[f64], + num_det: usize, + t_start: f64, + t_end: f64, +) -> (Vec, String) { + let mut in_window = vec![false; num_det]; + let mut local_to_global: Vec = Vec::new(); + let mut global_to_local: Vec> = vec![None; num_det]; + + for (i, &t) in det_times.iter().enumerate() { + if t >= t_start && t < t_end { + in_window[i] = true; + global_to_local[i] = Some(local_to_global.len() as u32); + local_to_global.push(i as u32); + } + } + + let mut out = String::new(); + + for line in dem.lines() { + let trimmed = line.trim(); + if trimmed.is_empty() || trimmed.starts_with('#') { + continue; + } + + if trimmed.starts_with("error(") { + let close = match trimmed.find(')') { + Some(p) => p, + None => continue, + }; + let prob_str = &trimmed[6..close]; + let rest = &trimmed[close + 1..]; + let tokens: Vec<&str> = rest.split_whitespace().collect(); + + // Split by ^ into decomposed segments. + let mut segments: Vec> = vec![Vec::new()]; + for tok in &tokens { + if *tok == "^" { + segments.push(Vec::new()); + } else { + segments.last_mut().unwrap().push(tok); + } + } + + let mut remapped_segments: Vec = Vec::new(); + for seg in &segments { + let mut seg_dets: Vec = Vec::new(); + let mut seg_obs: Vec = Vec::new(); + let mut seg_any_in = false; + + for tok in seg { + if let Some(d_str) = tok.strip_prefix('D') { + if let Ok(d) = d_str.parse::() + && d < num_det && in_window[d] { + seg_any_in = true; + if let Some(local) = global_to_local[d] { + seg_dets.push(format!("D{local}")); + } + } + } else if tok.starts_with('L') { + seg_obs.push((*tok).to_string()); + } + } + + if seg_any_in { + let mut seg_str = seg_dets.join(" "); + for obs in &seg_obs { + seg_str.push(' '); + seg_str.push_str(obs); + } + remapped_segments.push(seg_str); + } + } + + if !remapped_segments.is_empty() { + out.push_str(&format!("error({prob_str}) ")); + out.push_str(&remapped_segments.join(" ^ ")); + out.push('\n'); + } + } else if trimmed.starts_with("detector(") + && let Some(d_start) = trimmed.rfind('D') + && let Ok(d) = trimmed[d_start + 1..].trim().parse::() + && d < num_det && in_window[d] + && let Some(local) = global_to_local[d] { + let coords_end = trimmed.find(')').unwrap_or(trimmed.len()); + out.push_str(&trimmed[..=coords_end]); + out.push_str(&format!(" D{local}\n")); + } + } + + (local_to_global, out) +} + +// ============================================================================= +// Streaming windowed decoder +// ============================================================================= + +use std::collections::BTreeMap; + +/// Streaming windowed decoder that accepts syndrome data round-by-round. +/// +/// Precomputes round-to-detector mapping from DEM coordinates. As rounds +/// arrive via `feed_round`, buffers syndrome data and triggers window +/// decoding when each window's extended region is complete. Emits partial +/// observable corrections as windows commit. +pub struct StreamingWindowedDecoder { + /// Prebuilt windows, ordered by start time. + windows: Vec>, + /// Round number → list of (`local_window_idx`, `local_detector_idx`) for each window. + round_to_dets: BTreeMap>, + /// Per-window syndrome buffers. + window_syndromes: Vec>, + /// Round at which each window becomes decodable (all data received). + window_ready_round: Vec, + /// Index of next window to decode. + next_decode: usize, + /// Accumulated observable corrections. + accumulated: u64, +} + +impl StreamingWindowedDecoder { + /// Create from a DEM string with factory. + /// + /// # Errors + /// + /// Returns `DecoderError` if the DEM is malformed or factory fails. + pub fn from_dem( + dem: &str, + config: WindowedConfig, + mut factory: F, + ) -> Result + where + F: FnMut(&str) -> Result, + { + let (det_times, num_detectors, step_size, total_t) = parse_dem_params(dem, &config)?; + let buffer_size = config.buffer_size; + + // Build windows (same as OverlappingWindowedDecoder). + let mut windows = Vec::new(); + let mut window_ranges: Vec<(f64, f64, f64)> = Vec::new(); // (win_start, win_end, core_end) + let mut t_start = 0.0f64; + + while t_start < total_t { + let is_last = t_start + 2.0 * step_size as f64 > total_t; + let t_core_end = if is_last { + total_t + 1.0 + } else { + t_start + step_size as f64 + }; + let t_win_start = (t_start - buffer_size as f64).max(0.0); + let t_win_end = if is_last { + total_t + 1.0 + } else { + t_core_end + buffer_size as f64 + }; + + let (local_to_global, window_dem) = + extract_window_dem(dem, &det_times, num_detectors, t_win_start, t_win_end); + + let ext = config.core_extend as f64; + let is_core: Vec = local_to_global + .iter() + .map(|&gid| { + let t = det_times[gid as usize]; + t >= (t_start - ext) && t < (t_core_end + ext) + }) + .collect(); + + let num_local = local_to_global.len(); + if num_local > 0 && !window_dem.is_empty() { + let decoder = factory(&window_dem)?; + window_ranges.push((t_win_start, t_win_end, t_core_end)); + windows.push(OverlappingWindow { + decoder, + local_to_global, + is_core, + num_local, + }); + } + + t_start += step_size as f64; + } + + // Build round → (window_idx, local_det) mapping. + let mut round_to_dets: BTreeMap> = BTreeMap::new(); + for (win_idx, window) in windows.iter().enumerate() { + for (local_id, &global_id) in window.local_to_global.iter().enumerate() { + let round = det_times[global_id as usize] as usize; + round_to_dets + .entry(round) + .or_default() + .push((win_idx, local_id)); + } + } + + // Compute when each window has all its data. + let window_ready_round: Vec = window_ranges + .iter() + .map(|&(_, t_end, _)| (t_end.ceil() as usize).saturating_sub(1)) + .collect(); + + let window_syndromes = windows.iter().map(|w| vec![0u8; w.num_local]).collect(); + + Ok(Self { + windows, + round_to_dets, + window_syndromes, + window_ready_round, + next_decode: 0, + accumulated: 0, + }) + } + + /// Decode a ready window and return its observable contribution. + fn decode_window(&mut self, win_idx: usize) -> Result { + let window = &mut self.windows[win_idx]; + let syn = &self.window_syndromes[win_idx]; + + let (_, matched_edges) = window.decoder.decode_with_matching(syn)?; + + let mut obs = 0u64; + let boundary = window.num_local as u32; + for &edge_idx in &matched_edges { + let n1 = window.decoder.edge_node1(edge_idx); + let n2 = window.decoder.edge_node2(edge_idx); + + let n1_core = n1 >= boundary + || ((n1 as usize) < window.is_core.len() && window.is_core[n1 as usize]); + let n2_core = n2 >= boundary + || ((n2 as usize) < window.is_core.len() && window.is_core[n2 as usize]); + + if n1_core && n2_core { + obs ^= window.decoder.edge_obs_mask(edge_idx); + } + } + Ok(obs) + } +} + +impl pecos_decoder_core::streaming::StreamingDecoder + for StreamingWindowedDecoder +{ + fn feed_round(&mut self, round: usize, detectors: &[(u32, u8)]) -> Result { + // Store detection events into each window's syndrome buffer. + for &(det, val) in detectors { + if let Some(entries) = self.round_to_dets.get(&round) { + for &(win_idx, local_id) in entries { + // Check if this detector matches + if self.windows[win_idx].local_to_global.get(local_id) == Some(&det) { + self.window_syndromes[win_idx][local_id] = val; + } + } + } + } + + // Also store by global detector index for windows that contain this detector. + for &(det, val) in detectors { + for (win_idx, window) in self.windows.iter().enumerate() { + for (local_id, &global_id) in window.local_to_global.iter().enumerate() { + if global_id == det { + self.window_syndromes[win_idx][local_id] = val; + } + } + } + } + + // Check if any window became ready. + let mut new_obs = 0u64; + while self.next_decode < self.windows.len() { + if round < self.window_ready_round[self.next_decode] { + break; + } + new_obs ^= self.decode_window(self.next_decode)?; + self.next_decode += 1; + } + + self.accumulated ^= new_obs; + Ok(new_obs) + } + + fn flush(&mut self) -> Result { + let mut new_obs = 0u64; + while self.next_decode < self.windows.len() { + new_obs ^= self.decode_window(self.next_decode)?; + self.next_decode += 1; + } + self.accumulated ^= new_obs; + Ok(new_obs) + } + + fn accumulated_obs(&self) -> u64 { + self.accumulated + } + + fn reset(&mut self) { + for syn in &mut self.window_syndromes { + syn.fill(0); + } + self.next_decode = 0; + self.accumulated = 0; + } +} + +// ============================================================================= +// Beam search windowed decoder +// ============================================================================= + +/// Configuration for the beam search windowed decoder. +#[derive(Debug, Clone, Copy)] +pub struct BeamSearchConfig { + /// Windowed decoder parameters. + pub window: WindowedConfig, + /// Number of beam hypotheses (K). Default 5. + pub beam_width: usize, + /// Perturbation sigma for log-normal weight noise. Default 0.5. + pub perturbation_sigma: f64, + /// RNG seed for reproducibility. + pub seed: u64, +} + +impl Default for BeamSearchConfig { + fn default() -> Self { + Self { + window: WindowedConfig::default(), + beam_width: 5, + perturbation_sigma: 0.5, + seed: 42, + } + } +} + +/// One beam hypothesis: accumulated state from windows processed so far. +struct Hypothesis { + correction_effect: Vec, + obs_mask: u64, + total_weight: f64, +} + +/// Per-window storage: K decoders (1 unperturbed + K-1 perturbed). +struct BeamWindow { + decoders: Vec, + local_to_global: Vec, + is_core: Vec, + num_local: usize, +} + +/// Beam search windowed decoder. +/// +/// Maintains K correction hypotheses across window boundaries. Each window +/// expands K hypotheses × K perturbed decoders = K² candidates, pruned +/// to K by total correction weight. After all windows, picks the +/// lowest-weight hypothesis and optionally runs a Phase-2 residual decode. +/// +/// The key insight: different hypotheses propagate different +/// `correction_effect` vectors to subsequent windows, so each hypothesis +/// sees a different modified syndrome. This explores different string +/// continuations across window boundaries. +pub struct BeamSearchWindowedDecoder { + windows: Vec>, + num_detectors: usize, + beam_width: usize, + commit_weight_max: f64, + residual_decoder: Option>, +} + +impl BeamSearchWindowedDecoder { + /// Create from a DEM string. + /// + /// `phase1_factory` builds the inner edge-tracking decoder from a sub-DEM. + /// `phase2_factory` (optional) builds the full-graph residual decoder. + /// + /// # Errors + /// + /// Returns `DecoderError` if the DEM is malformed or factories fail. + pub fn from_dem( + dem: &str, + config: BeamSearchConfig, + mut phase1_factory: F1, + mut phase2_factory: Option, + ) -> Result + where + F1: FnMut(&str) -> Result, + F2: FnMut(&str) -> Result, DecoderError>, + { + let (det_times, num_detectors, step_size, total_t) = parse_dem_params(dem, &config.window)?; + let buffer_size = config.window.buffer_size; + let k = config.beam_width; + + let mut windows = Vec::new(); + let mut t_start = 0.0f64; + + while t_start < total_t { + let is_last = t_start + 2.0 * step_size as f64 > total_t; + let t_core_end = if is_last { + total_t + 1.0 + } else { + t_start + step_size as f64 + }; + let t_win_start = (t_start - buffer_size as f64).max(0.0); + let t_win_end = if is_last { + total_t + 1.0 + } else { + t_core_end + buffer_size as f64 + }; + + let (local_to_global, window_dem) = + extract_window_dem(dem, &det_times, num_detectors, t_win_start, t_win_end); + + let ext = config.window.core_extend as f64; + let is_core: Vec = local_to_global + .iter() + .map(|&gid| { + let t = det_times[gid as usize]; + t >= (t_start - ext) && t < (t_core_end + ext) + }) + .collect(); + + let num_local = local_to_global.len(); + if num_local > 0 && !window_dem.is_empty() { + let mut decoders = Vec::with_capacity(k); + + // Decoder 0: unperturbed anchor + decoders.push(phase1_factory(&window_dem)?); + + // Decoders 1..K-1: perturbed weights + for member_idx in 1..k { + let mut rng = pecos_random::PecosRng::seed_from_u64( + config.seed.wrapping_add(member_idx as u64), + ); + let mut next_f64 = || rng.next_f64(); + let perturbed = pecos_decoder_core::perturbed::perturb_dem( + &window_dem, + config.perturbation_sigma, + &mut next_f64, + ); + if let Ok(dec) = phase1_factory(&perturbed) { + decoders.push(dec); + } + } + + windows.push(BeamWindow { + decoders, + local_to_global, + is_core, + num_local, + }); + } + + t_start += step_size as f64; + } + + let residual_decoder = if let Some(ref mut f2) = phase2_factory { + Some(f2(dem)?) + } else { + None + }; + + Ok(Self { + windows, + num_detectors, + beam_width: k, + commit_weight_max: config.window.commit_weight_max, + residual_decoder, + }) + } + + /// Number of windows. + #[must_use] + pub fn num_windows(&self) -> usize { + self.windows.len() + } +} + +impl ObservableDecoder for BeamSearchWindowedDecoder { + fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { + let k = self.beam_width; + let commit_weight_max = self.commit_weight_max; + + // Initialize beam with K identical empty hypotheses. + let mut beam: Vec = (0..k) + .map(|_| Hypothesis { + correction_effect: vec![0u8; self.num_detectors], + obs_mask: 0, + total_weight: 0.0, + }) + .collect(); + + // Process each window: expand K hypotheses × K decoders → prune to K. + for window in &mut self.windows { + let actual_k = window.decoders.len(); + let mut candidates: Vec = Vec::with_capacity(beam.len() * actual_k); + + // Build window syndrome from the original (Phase-1 windows are + // independent — correction_effect is only used for Phase-2 residual). + let mut window_syn = vec![0u8; window.num_local]; + for (local_id, &global_id) in window.local_to_global.iter().enumerate() { + let gid = global_id as usize; + if gid < syndrome.len() { + window_syn[local_id] = syndrome[gid]; + } + } + + for hyp in &beam { + // Decode with each perturbed decoder. + for decoder in &mut window.decoders { + let (_, matched_edges) = decoder.decode_with_matching(&window_syn)?; + + let mut new_obs = hyp.obs_mask; + let mut new_correction = hyp.correction_effect.clone(); + let mut new_weight = hyp.total_weight; + let boundary = window.num_local as u32; + + for &edge_idx in &matched_edges { + let n1 = decoder.edge_node1(edge_idx); + let n2 = decoder.edge_node2(edge_idx); + + let n1_core = n1 >= boundary + || ((n1 as usize) < window.is_core.len() + && window.is_core[n1 as usize]); + let n2_core = n2 >= boundary + || ((n2 as usize) < window.is_core.len() + && window.is_core[n2 as usize]); + + let weight_ok = commit_weight_max <= 0.0 + || decoder.edge_weight(edge_idx) <= commit_weight_max; + + if n1_core && n2_core && weight_ok { + new_obs ^= decoder.edge_obs_mask(edge_idx); + new_weight += decoder.edge_weight(edge_idx); + + if (n1 as usize) < window.num_local { + let gid = window.local_to_global[n1 as usize] as usize; + new_correction[gid] ^= 1; + } + if (n2 as usize) < window.num_local { + let gid = window.local_to_global[n2 as usize] as usize; + new_correction[gid] ^= 1; + } + } + } + + candidates.push(Hypothesis { + correction_effect: new_correction, + obs_mask: new_obs, + total_weight: new_weight, + }); + } + } + + // Prune: sort by total weight (lower = more likely), dedup, truncate. + candidates.sort_by(|a, b| { + a.total_weight + .partial_cmp(&b.total_weight) + .unwrap_or(std::cmp::Ordering::Equal) + }); + candidates.dedup_by(|a, b| a.correction_effect == b.correction_effect); + candidates.truncate(k); + beam = candidates; + } + + // Pick the result via majority vote across surviving hypotheses. + // Each hypothesis may have a different Phase-1 obs_mask; we also run + // Phase-2 on each to get the complete observable prediction. + if beam.is_empty() { + return Ok(0); + } + + // Collect final observable predictions from each hypothesis. + let mut predictions: Vec = Vec::with_capacity(beam.len()); + if let Some(ref mut residual_dec) = self.residual_decoder { + for hyp in &beam { + let mut residual_syn = vec![0u8; self.num_detectors]; + for (i, &s) in syndrome.iter().enumerate() { + if i < self.num_detectors { + residual_syn[i] = s ^ hyp.correction_effect[i]; + } + } + let phase2_obs = residual_dec.decode_to_observables(&residual_syn)?; + predictions.push(hyp.obs_mask ^ phase2_obs); + } + } else { + for hyp in &beam { + predictions.push(hyp.obs_mask); + } + } + + // Majority vote across hypotheses (per observable bit). + let half = predictions.len() / 2; + let mut result = 0u64; + for bit in 0..64u32 { + let mask = 1u64 << bit; + let count = predictions.iter().filter(|&&p| p & mask != 0).count(); + if count > half { + result |= mask; + } + } + Ok(result) + } +} + +#[cfg(test)] +mod tests { + use super::*; + + const D3_DEM: &str = + include_str!("../../../examples/surface_code_circuits/surface_code_d3_z_stim.dem"); + + fn uf_factory(dem: &str) -> Result, DecoderError> { + Ok(Box::new(crate::UfDecoder::from_dem( + dem, + crate::UfDecoderConfig::fast(), + )?)) + } + + fn uf_edge_factory(dem: &str) -> Result { + crate::UfDecoder::from_dem(dem, crate::UfDecoderConfig::windowed()) + } + + #[test] + fn test_windowed_construction() { + let dec = WindowedDecoder::from_dem(D3_DEM, WindowedConfig::default(), uf_factory); + assert!(dec.is_ok()); + assert!(dec.unwrap().num_windows() > 0); + } + + #[test] + fn test_windowed_no_errors() { + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let mut dec = + WindowedDecoder::from_dem(D3_DEM, WindowedConfig::default(), uf_factory).unwrap(); + let obs = dec.decode_to_observables(&vec![0u8; graph.num_detectors]); + assert!(obs.is_ok()); + assert_eq!(obs.unwrap(), 0); + } + + #[test] + fn test_single_window_matches_full() { + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let config = WindowedConfig { + step_size: 100, + buffer_size: 0, + ..Default::default() + }; + let mut wdec = WindowedDecoder::from_dem(D3_DEM, config, uf_factory).unwrap(); + let mut udec = crate::UfDecoder::from_dem(D3_DEM, crate::UfDecoderConfig::fast()).unwrap(); + + let syn = vec![0u8; graph.num_detectors]; + assert_eq!( + wdec.decode_to_observables(&syn).unwrap(), + udec.decode_to_observables(&syn).unwrap(), + ); + } + + #[test] + fn test_overlapping_construction() { + let config = WindowedConfig { + step_size: 3, + buffer_size: 2, + ..Default::default() + }; + let dec = OverlappingWindowedDecoder::from_dem(D3_DEM, config, uf_edge_factory); + assert!(dec.is_ok()); + assert!(dec.unwrap().num_windows() > 0); + } + + #[test] + fn test_overlapping_no_errors() { + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let config = WindowedConfig { + step_size: 3, + buffer_size: 2, + ..Default::default() + }; + let mut dec = + OverlappingWindowedDecoder::from_dem(D3_DEM, config, uf_edge_factory).unwrap(); + let obs = dec.decode_to_observables(&vec![0u8; graph.num_detectors]); + assert!(obs.is_ok()); + assert_eq!(obs.unwrap(), 0); + } + + #[test] + fn test_overlapping_single_window() { + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let config = WindowedConfig { + step_size: 100, + buffer_size: 5, + ..Default::default() + }; + let mut dec = + OverlappingWindowedDecoder::from_dem(D3_DEM, config, uf_edge_factory).unwrap(); + assert_eq!(dec.num_windows(), 1); + let syn = vec![0u8; graph.num_detectors]; + assert_eq!(dec.decode_to_observables(&syn).unwrap(), 0); + } + + #[test] + fn test_sandwich_construction() { + let config = WindowedConfig { + step_size: 3, + buffer_size: 3, + ..Default::default() + }; + let dec = SandwichWindowedDecoder::from_dem(D3_DEM, config, uf_edge_factory, uf_factory); + assert!(dec.is_ok()); + let dec = dec.unwrap(); + assert!(dec.num_windows() > 0); + } + + #[test] + fn test_sandwich_no_errors() { + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let config = WindowedConfig { + step_size: 3, + buffer_size: 3, + ..Default::default() + }; + let mut dec = + SandwichWindowedDecoder::from_dem(D3_DEM, config, uf_edge_factory, uf_factory).unwrap(); + let obs = dec.decode_to_observables(&vec![0u8; graph.num_detectors]); + assert!(obs.is_ok()); + assert_eq!(obs.unwrap(), 0); + } + + #[test] + fn test_sandwich_parallel_matches_sequential() { + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let config = WindowedConfig { + step_size: 3, + buffer_size: 3, + ..Default::default() + }; + let mut dec = + SandwichWindowedDecoder::from_dem(D3_DEM, config, uf_edge_factory, uf_factory).unwrap(); + + let syn = vec![0u8; graph.num_detectors]; + let seq = dec.decode_to_observables(&syn).unwrap(); + let par = dec.decode_parallel(&syn).unwrap(); + assert_eq!(seq, par); + } + + #[test] + fn test_streaming_construction() { + let config = WindowedConfig { + step_size: 3, + buffer_size: 2, + ..Default::default() + }; + let dec = StreamingWindowedDecoder::from_dem(D3_DEM, config, uf_edge_factory); + assert!(dec.is_ok()); + } + + #[test] + fn test_streaming_no_errors() { + use pecos_decoder_core::streaming::StreamingDecoder; + + let config = WindowedConfig { + step_size: 3, + buffer_size: 2, + ..Default::default() + }; + let mut dec = StreamingWindowedDecoder::from_dem(D3_DEM, config, uf_edge_factory).unwrap(); + + // Feed empty rounds — no detectors fire. + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let max_round = graph + .detector_coords + .iter() + .filter_map(|c| c.as_ref().and_then(|v| v.get(2)).copied()) + .fold(0.0f64, f64::max) as usize; + + for r in 0..=max_round { + dec.feed_round(r, &[]).unwrap(); + } + dec.flush().unwrap(); + assert_eq!(dec.accumulated_obs(), 0); + } + + #[test] + fn test_beam_k1_matches_sandwich_nonzero() { + // K=1 beam with non-zero syndrome should match sandwich. + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let wconfig = WindowedConfig { + step_size: 3, + buffer_size: 3, + commit_weight_max: 2.5, + ..Default::default() + }; + + let mut sandwich = + SandwichWindowedDecoder::from_dem(D3_DEM, wconfig, uf_edge_factory, uf_factory) + .unwrap(); + + let bconfig = BeamSearchConfig { + window: wconfig, + beam_width: 1, + perturbation_sigma: 0.0, + seed: 42, + }; + let mut beam = + BeamSearchWindowedDecoder::from_dem(D3_DEM, bconfig, uf_edge_factory, Some(uf_factory)) + .unwrap(); + + // Test with single-defect syndrome. + let mut syn = vec![0u8; graph.num_detectors]; + syn[0] = 1; + let sw_obs = sandwich.decode_to_observables(&syn).unwrap(); + let bm_obs = beam.decode_to_observables(&syn).unwrap(); + assert_eq!( + sw_obs, bm_obs, + "K=1 beam should match sandwich. sw={sw_obs}, bm={bm_obs}" + ); + + // Test with two defects. + syn[0] = 1; + syn[1] = 1; + let sw_obs = sandwich.decode_to_observables(&syn).unwrap(); + let bm_obs = beam.decode_to_observables(&syn).unwrap(); + assert_eq!( + sw_obs, bm_obs, + "K=1 beam should match sandwich on 2 defects. sw={sw_obs}, bm={bm_obs}" + ); + } + + #[test] + fn test_beam_search_construction() { + let config = BeamSearchConfig { + window: WindowedConfig { + step_size: 3, + buffer_size: 3, + ..Default::default() + }, + beam_width: 3, + perturbation_sigma: 0.5, + seed: 42, + }; + let dec = + BeamSearchWindowedDecoder::from_dem(D3_DEM, config, uf_edge_factory, Some(uf_factory)); + assert!(dec.is_ok()); + assert!(dec.unwrap().num_windows() > 0); + } + + #[test] + fn test_beam_k1_matches_sandwich() { + // K=1 beam with no perturbation should match the sandwich decoder. + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let wconfig = WindowedConfig { + step_size: 3, + buffer_size: 3, + commit_weight_max: 2.5, + ..Default::default() + }; + + // Sandwich + let mut sandwich = + SandwichWindowedDecoder::from_dem(D3_DEM, wconfig, uf_edge_factory, uf_factory) + .unwrap(); + + // Beam K=1 + let bconfig = BeamSearchConfig { + window: wconfig, + beam_width: 1, + perturbation_sigma: 0.0, + seed: 42, + }; + let mut beam = + BeamSearchWindowedDecoder::from_dem(D3_DEM, bconfig, uf_edge_factory, Some(uf_factory)) + .unwrap(); + + let syn = vec![0u8; graph.num_detectors]; + let sw_obs = sandwich.decode_to_observables(&syn).unwrap(); + let bm_obs = beam.decode_to_observables(&syn).unwrap(); + assert_eq!( + sw_obs, bm_obs, + "K=1 beam should match sandwich on zero syndrome" + ); + } + + #[test] + fn test_beam_search_no_errors() { + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let config = BeamSearchConfig { + window: WindowedConfig { + step_size: 3, + buffer_size: 3, + ..Default::default() + }, + beam_width: 3, + perturbation_sigma: 0.5, + seed: 42, + }; + let mut dec = + BeamSearchWindowedDecoder::from_dem(D3_DEM, config, uf_edge_factory, Some(uf_factory)) + .unwrap(); + let obs = dec.decode_to_observables(&vec![0u8; graph.num_detectors]); + assert!(obs.is_ok()); + assert_eq!(obs.unwrap(), 0); + } +} diff --git a/crates/pecos-uf-decoder/tests/cross_decoder_tests.rs b/crates/pecos-uf-decoder/tests/cross_decoder_tests.rs new file mode 100644 index 000000000..d7bec84d7 --- /dev/null +++ b/crates/pecos-uf-decoder/tests/cross_decoder_tests.rs @@ -0,0 +1,118 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Cross-decoder comparison: UF vs itself (consistency checks). +//! +//! We can't depend on pecos-pymatching here (C++ build), but we CAN +//! verify that UF + ensemble composed of UF decoders all agree. + +use pecos_decoder_core::ObservableDecoder; +use pecos_decoder_core::dem::DemMatchingGraph; +use pecos_decoder_core::ensemble::EnsembleDecoder; +use pecos_uf_decoder::{UfDecoder, UfDecoderConfig}; + +const D3_DEM: &str = + include_str!("../../../examples/surface_code_circuits/surface_code_d3_z_stim.dem"); + +/// An ensemble of 3 identical UF decoders must agree with a single UF decoder +/// on every syndrome (since all members produce the same result, the majority +/// vote is identical to any single member). +#[test] +fn test_ensemble_of_identical_decoders_matches_single() { + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + + let mut single = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::default()); + let members: Vec> = (0..3) + .map(|_| { + Box::new(UfDecoder::from_matching_graph( + &graph, + UfDecoderConfig::default(), + )) as Box + }) + .collect(); + let mut ensemble = EnsembleDecoder::new(members); + + let mut rng = fastrand::Rng::with_seed(123); + for _ in 0..500 { + let mut syndrome = vec![0u8; graph.num_detectors]; + for s in &mut syndrome { + if rng.f64() < 0.05 { + *s = 1; + } + } + + let single_obs = single.decode_to_observables(&syndrome).unwrap(); + let ensemble_obs = ensemble.decode_to_observables(&syndrome).unwrap(); + assert_eq!( + single_obs, ensemble_obs, + "Ensemble of identical decoders diverged from single decoder" + ); + } +} + +/// Verify the UF decoder produces deterministic results across runs. +#[test] +fn test_deterministic_results() { + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + + let mut dec1 = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::default()); + let mut dec2 = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::default()); + + let mut rng = fastrand::Rng::with_seed(999); + for _ in 0..200 { + let mut syndrome = vec![0u8; graph.num_detectors]; + for s in &mut syndrome { + if rng.f64() < 0.08 { + *s = 1; + } + } + + let r1 = dec1.decode_to_observables(&syndrome).unwrap(); + let r2 = dec2.decode_to_observables(&syndrome).unwrap(); + assert_eq!(r1, r2, "Two identical decoders gave different results"); + } +} + +/// Test `MatchingDecoder` consistency: `decode_with_matching` and `decode_to_observables` +/// must agree on the observable mask. +#[test] +fn test_matching_agrees_with_observable() { + use pecos_decoder_core::correlated_decoder::MatchingDecoder; + + let graph = DemMatchingGraph::from_dem_str(D3_DEM).unwrap(); + let mut dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::default()); + + let mut rng = fastrand::Rng::with_seed(777); + for _ in 0..200 { + let mut syndrome = vec![0u8; graph.num_detectors]; + for s in &mut syndrome { + if rng.f64() < 0.06 { + *s = 1; + } + } + + let obs = dec.decode_to_observables(&syndrome).unwrap(); + + // Reset and decode again with matching + let (match_obs, edges) = dec.decode_with_matching(&syndrome).unwrap(); + + assert_eq!( + obs, match_obs, + "ObservableDecoder and MatchingDecoder disagree on observable mask" + ); + + // If there are matched edges, they should be valid indices + for &e in &edges { + assert!(e < dec.num_edges(), "Edge index {e} out of range"); + } + } +} diff --git a/crates/pecos-uf-decoder/tests/integration_tests.rs b/crates/pecos-uf-decoder/tests/integration_tests.rs new file mode 100644 index 000000000..985a179b9 --- /dev/null +++ b/crates/pecos-uf-decoder/tests/integration_tests.rs @@ -0,0 +1,173 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Integration tests for the UF decoder using realistic surface code DEMs. + +use pecos_decoder_core::ObservableDecoder; +use pecos_decoder_core::dem::DemMatchingGraph; +use pecos_uf_decoder::{UfDecoder, UfDecoderConfig}; + +/// Distance-3 rotated surface code, Z basis, 3 rounds of syndrome extraction. +/// This is a realistic DEM with 24 detectors and ~100 error mechanisms. +/// Non-decomposed (for matching graph extraction). +const D3_SURFACE_CODE_DEM: &str = + include_str!("../../../examples/surface_code_circuits/surface_code_d3_z_stim.dem"); + +/// Check the decoder initializes correctly from a real surface code DEM. +#[test] +fn test_real_dem_construction() { + let graph = DemMatchingGraph::from_dem_str(D3_SURFACE_CODE_DEM).unwrap(); + assert!( + graph.num_detectors >= 20, + "Expected 20+ detectors, got {}", + graph.num_detectors + ); + assert!( + graph.edges.len() >= 10, + "Expected 10+ edges, got {}", + graph.edges.len() + ); + + let dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::default()); + assert_eq!(dec.num_detectors(), graph.num_detectors); + assert_eq!(dec.num_edges(), graph.edges.len()); +} + +/// Decode the trivial (no-error) syndrome -- should always give observable 0. +#[test] +fn test_real_dem_no_errors() { + let graph = DemMatchingGraph::from_dem_str(D3_SURFACE_CODE_DEM).unwrap(); + let mut dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::default()); + let syndrome = vec![0u8; graph.num_detectors]; + assert_eq!(dec.decode_syndrome(&syndrome), 0); +} + +/// Decode single-defect syndromes (one detector triggered). +/// Each should produce a valid correction (not panic, not hang). +#[test] +fn test_real_dem_single_defects() { + let graph = DemMatchingGraph::from_dem_str(D3_SURFACE_CODE_DEM).unwrap(); + let mut dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::default()); + + for d in 0..graph.num_detectors { + let mut syndrome = vec![0u8; graph.num_detectors]; + syndrome[d] = 1; + // Should not panic or hang. Observable is either 0 or 1. + let obs = dec.decode_syndrome(&syndrome); + assert!( + obs <= 1, + "Observable mask {obs} too large for single-observable DEM" + ); + } +} + +/// Decode syndromes with two adjacent defects. +/// For each edge in the matching graph, set both endpoint detectors and decode. +#[test] +fn test_real_dem_adjacent_pairs() { + let graph = DemMatchingGraph::from_dem_str(D3_SURFACE_CODE_DEM).unwrap(); + let mut dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::default()); + + for edge in &graph.edges { + let mut syndrome = vec![0u8; graph.num_detectors]; + syndrome[edge.node1 as usize] = 1; + if let Some(n2) = edge.node2 { + syndrome[n2 as usize] = 1; + } + let obs = dec.decode_syndrome(&syndrome); + assert!(obs <= 1, "Observable mask {obs} too large"); + } +} + +/// Stress test: decode many random syndromes with even number of defects. +/// Verify the decoder never panics or hangs, and results are in range. +#[test] +fn test_real_dem_random_syndromes() { + let graph = DemMatchingGraph::from_dem_str(D3_SURFACE_CODE_DEM).unwrap(); + let mut dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::default()); + let mut rng = fastrand::Rng::with_seed(42); + + for _ in 0..1000 { + let mut syndrome = vec![0u8; graph.num_detectors]; + let mut num_defects = 0; + for s in &mut syndrome { + if rng.f64() < 0.05 { + *s = 1; + num_defects += 1; + } + } + // Ensure even number of defects (valid syndrome for surface codes). + if num_defects % 2 != 0 && !syndrome.is_empty() { + // Flip a random detector to make it even. + let idx = rng.usize(..syndrome.len()); + syndrome[idx] ^= 1; + } + + let obs = dec.decode_syndrome(&syndrome); + assert!(obs <= 1, "Observable mask {obs} too large"); + } +} + +/// Test via the `ObservableDecoder` trait (the actual interface used in production). +#[test] +fn test_observable_decoder_trait_real_dem() { + let graph = DemMatchingGraph::from_dem_str(D3_SURFACE_CODE_DEM).unwrap(); + let mut dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::default()); + let syndrome = vec![0u8; graph.num_detectors]; + let result = dec.decode_to_observables(&syndrome); + assert!(result.is_ok()); + assert_eq!(result.unwrap(), 0); +} + +/// Test `MatchingDecoder` trait on real DEM. +#[test] +fn test_matching_decoder_trait_real_dem() { + use pecos_decoder_core::correlated_decoder::MatchingDecoder; + let graph = DemMatchingGraph::from_dem_str(D3_SURFACE_CODE_DEM).unwrap(); + let mut dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::default()); + + // Two adjacent defects. + let edge = &graph.edges[0]; + let mut syndrome = vec![0u8; graph.num_detectors]; + syndrome[edge.node1 as usize] = 1; + if let Some(n2) = edge.node2 { + syndrome[n2 as usize] = 1; + } + + let (obs, _matched_edges) = dec.decode_with_matching(&syndrome).unwrap(); + assert!(obs <= 1); + // Predecoder may handle simple cases without tracking edges. + assert!(obs <= 1); +} + +/// Buffer reuse stress test: alternate between zero and non-zero syndromes. +/// Catches bugs where state leaks between shots. +#[test] +fn test_buffer_reuse_correctness() { + let graph = DemMatchingGraph::from_dem_str(D3_SURFACE_CODE_DEM).unwrap(); + let mut dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::default()); + let zero_syndrome = vec![0u8; graph.num_detectors]; + + let mut defect_syndrome = vec![0u8; graph.num_detectors]; + defect_syndrome[0] = 1; + + for _ in 0..500 { + // Zero syndrome must always give 0. + assert_eq!( + dec.decode_syndrome(&zero_syndrome), + 0, + "Buffer leak: non-zero after defect" + ); + // Defect syndrome should give a consistent result. + let _ = dec.decode_syndrome(&defect_syndrome); + } +} diff --git a/crates/pecos/src/lib.rs b/crates/pecos/src/lib.rs index 8258552ff..44588d851 100644 --- a/crates/pecos/src/lib.rs +++ b/crates/pecos/src/lib.rs @@ -68,13 +68,13 @@ pub mod simulators { #[cfg(feature = "cppsparsestab")] pub use pecos_cppsparsestab::CppSparseStab; pub use pecos_engines::quantum::{ - CliffordRzEngine, DensityMatrixEngine, QuantumEngine, SparseStabEngine, StabilizerEngine, + DensityMatrixEngine, QuantumEngine, SparseStabEngine, StabVecEngine, StabilizerEngine, StateVecEngine, new_quantum_engine_arbitrary_qgate, }; pub use pecos_engines::quantum_engine_builder::{ - CliffordRzEngineBuilder, DensityMatrixEngineBuilder, IntoQuantumEngineBuilder, - SparseStabEngineBuilder, StabilizerEngineBuilder, StateVectorEngineBuilder, clifford_rz, - density_matrix, sparse_stab, stabilizer, state_vector, + DensityMatrixEngineBuilder, IntoQuantumEngineBuilder, SparseStabEngineBuilder, + StabVecEngineBuilder, StabilizerEngineBuilder, StateVectorEngineBuilder, density_matrix, + sparse_stab, stab_vec, stabilizer, state_vector, }; pub use pecos_simulators::*; } @@ -201,7 +201,7 @@ pub use pecos_engines::{ pub use pecos_engines::{SimInput, sim_builder}; #[cfg(feature = "sim")] pub use pecos_engines::{ - clifford_rz, coin_toss, density_matrix, sparse_stab, stabilizer, state_vector, + coin_toss, density_matrix, sparse_stab, stab_vec, stabilizer, state_vector, }; #[cfg(feature = "hugr")] pub use pecos_hugr::{HugrEngine, HugrEngineBuilder, hugr_engine, hugr_sim}; diff --git a/design/pecos-cuquantum-plan.md b/design/pecos-cuquantum-plan.md deleted file mode 100644 index fa6ed9606..000000000 --- a/design/pecos-cuquantum-plan.md +++ /dev/null @@ -1,225 +0,0 @@ -# Plan: pecos-cuquantum Crate - -## Overview - -Create Rust bindings for NVIDIA's [cuQuantum SDK](https://developer.nvidia.com/cuquantum-sdk) to provide CUDA-accelerated quantum simulation in PECOS. - -## cuQuantum SDK Components - -The SDK includes five libraries (as of v25.x): - -| Library | Purpose | PECOS Relevance | -|---------|---------|-----------------| -| **cuStateVec** | State vector simulation | Alternative to `GpuStateVec` (wgpu) | -| **cuStabilizer** | Stabilizer/Clifford simulation | Alternative to `GpuStab`/`GpuStabMulti` | -| **cuTensorNet** | Tensor network contraction | Advanced simulation methods | -| **cuDensityMat** | Density matrix simulation | Noise modeling | -| **cuPauliProp** | Pauli propagation | Efficient Pauli tracking | - -**Priority**: cuStateVec and cuStabilizer are most relevant initially. - -## Architecture - -``` -pecos-cuquantum-sys/ # Raw FFI bindings (generated by bindgen) - src/ - lib.rs # bindgen output + manual additions - build.rs # Find/download cuQuantum, run bindgen - -pecos-cuquantum/ # Safe Rust wrapper - src/ - lib.rs - statevec.rs # cuStateVec wrapper - stabilizer.rs # cuStabilizer wrapper - error.rs # Error handling - build.rs # Link configuration -``` - -## Dependency Management - -### Option 1: System Installation (Preferred for users with CUDA) -- Check `CUQUANTUM_ROOT` environment variable -- Check standard paths: `/usr/local/cuquantum`, `/opt/nvidia/cuquantum` -- Check if installed via apt/conda - -### Option 2: Auto-download to ~/.pecos/cuquantum/ -- Download tarball from NVIDIA (requires accepting license) -- Extract to `~/.pecos/cuquantum//` -- Cache for reuse across builds - -### Detection Order (similar to pecos-build cuda.rs) -```rust -pub fn find_cuquantum() -> Option { - // 1. ~/.pecos/cuquantum/ - // 2. CUQUANTUM_ROOT env var - // 3. Standard system paths - // 4. Derive from ldconfig/pkg-config -} -``` - -## C API Bindings - -### Header Files -```c -#include // State vector API -#include // Stabilizer API (if available) -#include // Complex number types -``` - -### Key cuStateVec Functions -```c -// Handle management -custatevecCreate(custatevecHandle_t* handle); -custatevecDestroy(custatevecHandle_t handle); - -// Gate application -custatevecApplyMatrix(handle, sv, dataType, nQubits, matrix, ...); -custatevecApplyMatrixGetWorkspaceSize(...); - -// Measurement -custatevecMeasure(handle, sv, dataType, nQubits, ...); -custatevecSample(handle, sv, dataType, nQubits, ...); - -// Expectation -custatevecComputeExpectation(...); -``` - -### bindgen Configuration -```rust -// build.rs -let bindings = bindgen::Builder::default() - .header("wrapper.h") - .clang_arg(format!("-I{}/include", cuquantum_path)) - .clang_arg(format!("-I{}/include", cuda_path)) - .allowlist_function("custatevec.*") - .allowlist_type("custatevec.*") - .allowlist_var("CUSTATEVEC_.*") - .generate() - .expect("Failed to generate bindings"); -``` - -## Safe Rust API Design - -### CuStateVec -```rust -pub struct CuStateVec { - handle: custatevecHandle_t, - state: DeviceBuffer, - num_qubits: usize, -} - -impl CuStateVec { - pub fn new(num_qubits: usize) -> Result; - - // Gate application - pub fn apply_matrix(&mut self, targets: &[usize], matrix: &[Complex64]) -> Result<(), _>; - pub fn h(&mut self, qubit: usize) -> Result<(), _>; - pub fn cx(&mut self, control: usize, target: usize) -> Result<(), _>; - // ... other gates - - // Measurement - pub fn measure(&mut self, qubit: usize) -> Result; - pub fn sample(&mut self, num_samples: usize) -> Result, _>; -} - -// Implement PECOS traits -impl CliffordGateable for CuStateVec { ... } -impl Measurable for CuStateVec { ... } -``` - -### CuStabilizer (if SDK includes it) -```rust -pub struct CuStabilizer { - // Wrapper for cuStabilizer -} - -impl CliffordGateable for CuStabilizer { ... } -``` - -## Build System Integration - -### pecos.toml Addition -```toml -[dependencies.cuquantum] -version = "25.11.0" -url = "https://developer.download.nvidia.com/..." # If redistributable -sha256 = "..." -description = "NVIDIA cuQuantum SDK" -requires_cuda = true - -[crates.pecos-cuquantum] -dependencies = ["cuquantum"] -requires_cuda = true -optional = true # Don't fail if CUDA unavailable -``` - -### Feature Flags -```toml -# pecos-cuquantum/Cargo.toml -[features] -default = [] -cuda-12 = [] # Link against CUDA 12 -cuda-11 = [] # Link against CUDA 11 -download = [] # Auto-download cuQuantum if not found -``` - -## Implementation Steps - -### Phase 1: Foundation -1. Add cuQuantum detection to `pecos-build/src/cuquantum.rs` -2. Create `pecos-cuquantum-sys` crate with bindgen -3. Verify bindings compile and link - -### Phase 2: Safe Wrapper -4. Create `pecos-cuquantum` crate -5. Implement `CuStateVec` wrapper -6. Add basic gates (H, X, Y, Z, S, T, CX, CZ) -7. Add measurement and sampling - -### Phase 3: PECOS Integration -8. Implement `CliffordGateable` trait -9. Add benchmarks comparing to `GpuStateVec` -10. Add cuStabilizer wrapper if available - -### Phase 4: Polish -11. Error handling improvements -12. Documentation -13. CI testing (requires CUDA runner) - -## Considerations - -### License -- cuQuantum SDK has its own license (not open source) -- Need to handle redistribution carefully -- May need to download at build time rather than bundle - -### CUDA Version Compatibility -- cuQuantum requires specific CUDA versions -- Need to match CUDA toolkit version -- pecos-build already handles CUDA detection - -### Multi-GPU Support -- cuStateVec supports multi-GPU via cuStateVecEx -- Consider exposing this for large simulations - -### Comparison with wgpu Backend -| Aspect | wgpu (GpuStateVec) | cuQuantum | -|--------|-------------------|-----------| -| Portability | Cross-platform | NVIDIA only | -| Performance | Good | Optimized for NVIDIA | -| Dependencies | Minimal | CUDA + cuQuantum | -| Maintenance | In-house | NVIDIA maintained | - -## Open Questions - -1. **cuStabilizer availability**: Is cuStabilizer a separate library or part of cuStateVec? -2. **License for auto-download**: Can we auto-download or must users accept license manually? -3. **Minimum CUDA version**: What CUDA versions should we support? -4. **Testing infrastructure**: Do we have CI runners with NVIDIA GPUs? - -## References - -- [cuQuantum Documentation](https://docs.nvidia.com/cuda/cuquantum/latest/index.html) -- [cuStateVec API Reference](https://docs.nvidia.com/cuda/cuquantum/latest/custatevec/index.html) -- [cuQuantum GitHub Samples](https://github.com/NVIDIA/cuQuantum/tree/main/samples) -- [Getting Started Guide](https://docs.nvidia.com/cuda/cuquantum/latest/getting-started/index.html) diff --git a/design/proposals/byte_message_api_cleanup.md b/design/proposals/byte_message_api_cleanup.md deleted file mode 100644 index a1c69daaf..000000000 --- a/design/proposals/byte_message_api_cleanup.md +++ /dev/null @@ -1,36 +0,0 @@ -# ByteMessageBuilder API Cleanup - -## Changes Made - -### Rust API - -Two-qubit gates now take `&[(usize, usize)]` (slice of pairs) instead of separate slices: - -```rust -// Before: -builder.cx(&[0], &[1]); -builder.rzz(theta, &[0], &[1]); - -// After: -builder.cx(&[(0, 1)]); -builder.rzz(theta, &[(0, 1)]); - -// Batch: -builder.cx(&[(0, 1), (2, 3)]); -``` - -Affected methods: `cx`, `cy`, `cz`, `szz`, `szzdg`, `rzz` - -### Rename: `mz` -> `mz` - -The method name now matches the gate name (MZ). - -### Python API - -Single-qubit gates take lists: `h([0, 1, 2])` -Two-qubit gates take lists of tuples: `cx([(0, 1), (2, 3)])` -Measurements renamed: `mz([0, 1])` - -## Status - -Done. Both Rust and Python APIs updated. diff --git a/design/proposals/slr-ast.md b/design/proposals/slr-ast.md deleted file mode 100644 index 522168a4c..000000000 --- a/design/proposals/slr-ast.md +++ /dev/null @@ -1,973 +0,0 @@ -# SLR Abstract Syntax Tree (AST) Proposal - - - -## Status - -**Draft** - Ready for review - ---- - -## Motivation - -### Current State - -SLR currently uses Python classes directly as both the syntax and the runtime representation: - -```python -prog = Main( - q := QReg("q", 2), - c := CReg("c", 2), - qb.H(q[0]), - qb.CX(q[0], q[1]), - qb.Measure(q) > c, -) -``` - -This approach has drawbacks: - -1. **Mixed concerns**: Representation classes also contain execution logic -2. **Difficult analysis**: No clean separation for static analysis passes -3. **Inconsistent structure**: Different node types have different interfaces -4. **Hard to transform**: Modifying programs requires understanding implementation details -5. **Code generation complexity**: Generators work directly with heterogeneous objects - -### Benefits of a Formal AST - -1. **Clean separation**: Syntax representation separate from semantics -2. **Uniform interface**: All nodes share a common base with predictable structure -3. **Easy traversal**: Visitor pattern for analysis and transformation -4. **Better tooling**: Linting, formatting, refactoring tools -5. **Simpler code gen**: One AST → multiple targets (QASM, Guppy, HUGR, etc.) -6. **Integration with QAlloc**: Clean representation of allocator hierarchy and slot states - ---- - -## Design Principles - -### 1. Immutable Data Structures - -AST nodes should be immutable dataclasses. This enables: -- Safe sharing and caching -- Easy equality comparison -- Predictable behavior in analysis passes - -### 2. Type Safety - -Use Python's type system with generics and protocols: -- All nodes have precise types -- Analysis results are strongly typed -- IDE support for navigation and refactoring - -### 3. Location Tracking - -Every node can optionally track source location for error reporting: -```python -@dataclass(frozen=True) -class SourceLocation: - line: int - column: int - file: str | None = None -``` - -### 4. Visitor Pattern - -Support the visitor pattern for analysis and transformation: -```python -class ASTVisitor(Protocol[T]): - def visit_program(self, node: Program) -> T: ... - def visit_gate(self, node: GateOp) -> T: ... - - # etc. -``` - -### 5. Bidirectional Conversion - -The AST should support: -- Building from current SLR objects (`from_slr()`) -- Converting back for execution (`to_slr()`) -- Direct construction for new code - ---- - -## AST Node Hierarchy - -### Base Types - -```python -from __future__ import annotations -from abc import ABC, abstractmethod -from dataclasses import dataclass, field -from enum import Enum, auto -from typing import TypeVar, Generic, Protocol, Sequence - - -@dataclass(frozen=True) -class SourceLocation: - """Source location for error reporting.""" - - line: int - column: int - file: str | None = None - - -@dataclass(frozen=True) -class ASTNode(ABC): - """Base class for all AST nodes.""" - - location: SourceLocation | None = field(default=None, compare=False) - - @abstractmethod - def accept(self, visitor: ASTVisitor[T]) -> T: - """Accept a visitor for traversal.""" - ... - - def children(self) -> Sequence[ASTNode]: - """Return child nodes for traversal.""" - return () -``` - -### Program Structure - -```python -@dataclass(frozen=True) -class Program(ASTNode): - """Root node representing an SLR program.""" - - name: str - allocator: AllocatorDecl | None # Base allocator (required in strict mode) - declarations: tuple[Declaration, ...] - body: tuple[Statement, ...] - returns: tuple[TypeExpr, ...] = () - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_program(self) - - def children(self) -> Sequence[ASTNode]: - nodes = [] - if self.allocator: - nodes.append(self.allocator) - nodes.extend(self.declarations) - nodes.extend(self.body) - return nodes -``` - -### Declarations - -```python -class Declaration(ASTNode, ABC): - """Base for all declarations.""" - - pass - - -@dataclass(frozen=True) -class AllocatorDecl(Declaration): - """Qubit allocator declaration.""" - - name: str - capacity: int - parent: str | None = None # Name of parent allocator - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_allocator_decl(self) - - -@dataclass(frozen=True) -class RegisterDecl(Declaration): - """Classical register declaration.""" - - name: str - size: int - is_result: bool = True - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_register_decl(self) -``` - -### Statements - -```python -class Statement(ASTNode, ABC): - """Base for all statements.""" - - pass - - -@dataclass(frozen=True) -class GateOp(Statement): - """Quantum gate application.""" - - gate: GateKind - targets: tuple[SlotRef, ...] - params: tuple[Expression, ...] = () - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_gate(self) - - def children(self) -> Sequence[ASTNode]: - return (*self.targets, *self.params) - - -@dataclass(frozen=True) -class PrepareOp(Statement): - """Prepare qubit slots (unprepared -> prepared).""" - - allocator: str - slots: tuple[int, ...] | None = None # None means all slots - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_prepare(self) - - -@dataclass(frozen=True) -class MeasureOp(Statement): - """Measure qubit slots.""" - - targets: tuple[SlotRef, ...] - results: tuple[BitRef, ...] = () - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_measure(self) - - def children(self) -> Sequence[ASTNode]: - return (*self.targets, *self.results) - - -@dataclass(frozen=True) -class AssignOp(Statement): - """Classical assignment.""" - - target: BitRef | str # Variable or bit reference - value: Expression - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_assign(self) - - def children(self) -> Sequence[ASTNode]: - nodes = [self.value] - if isinstance(self.target, ASTNode): - nodes.insert(0, self.target) - return nodes - - -@dataclass(frozen=True) -class BarrierOp(Statement): - """Synchronization barrier.""" - - allocators: tuple[str, ...] = () - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_barrier(self) - - -@dataclass(frozen=True) -class CommentOp(Statement): - """Comment in generated code.""" - - text: str - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_comment(self) - - -@dataclass(frozen=True) -class ReturnOp(Statement): - """Return statement.""" - - values: tuple[Expression, ...] - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_return(self) - - def children(self) -> Sequence[ASTNode]: - return self.values -``` - -### Control Flow - -```python -@dataclass(frozen=True) -class IfStmt(Statement): - """Conditional execution.""" - - condition: Expression - then_body: tuple[Statement, ...] - else_body: tuple[Statement, ...] = () - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_if(self) - - def children(self) -> Sequence[ASTNode]: - return (self.condition, *self.then_body, *self.else_body) - - -@dataclass(frozen=True) -class WhileStmt(Statement): - """While loop.""" - - condition: Expression - body: tuple[Statement, ...] - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_while(self) - - def children(self) -> Sequence[ASTNode]: - return (self.condition, *self.body) - - -@dataclass(frozen=True) -class ForStmt(Statement): - """For loop with iteration variable.""" - - variable: str - start: Expression - stop: Expression - step: Expression | None = None - body: tuple[Statement, ...] - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_for(self) - - def children(self) -> Sequence[ASTNode]: - nodes = [self.start, self.stop] - if self.step: - nodes.append(self.step) - nodes.extend(self.body) - return nodes - - -@dataclass(frozen=True) -class RepeatStmt(Statement): - """Repeat N times.""" - - count: int - body: tuple[Statement, ...] - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_repeat(self) - - def children(self) -> Sequence[ASTNode]: - return self.body - - -@dataclass(frozen=True) -class ParallelBlock(Statement): - """Parallel execution hint.""" - - body: tuple[Statement, ...] - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_parallel(self) - - def children(self) -> Sequence[ASTNode]: - return self.body -``` - -### References - -```python -@dataclass(frozen=True) -class SlotRef(ASTNode): - """Reference to a qubit slot in an allocator.""" - - allocator: str - index: int - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_slot_ref(self) - - def __str__(self) -> str: - return f"{self.allocator}[{self.index}]" - - -@dataclass(frozen=True) -class BitRef(ASTNode): - """Reference to a classical bit in a register.""" - - register: str - index: int - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_bit_ref(self) - - def __str__(self) -> str: - return f"{self.register}[{self.index}]" -``` - -### Expressions - -```python -class Expression(ASTNode, ABC): - """Base for all expressions.""" - - pass - - -@dataclass(frozen=True) -class LiteralExpr(Expression): - """Literal value (int, float, bool).""" - - value: int | float | bool - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_literal(self) - - -@dataclass(frozen=True) -class VarExpr(Expression): - """Variable reference.""" - - name: str - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_var(self) - - -@dataclass(frozen=True) -class BitExpr(Expression): - """Bit reference as expression (for conditions).""" - - ref: BitRef - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_bit_expr(self) - - def children(self) -> Sequence[ASTNode]: - return (self.ref,) - - -@dataclass(frozen=True) -class BinaryExpr(Expression): - """Binary operation.""" - - op: BinaryOp - left: Expression - right: Expression - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_binary(self) - - def children(self) -> Sequence[ASTNode]: - return (self.left, self.right) - - -@dataclass(frozen=True) -class UnaryExpr(Expression): - """Unary operation.""" - - op: UnaryOp - operand: Expression - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_unary(self) - - def children(self) -> Sequence[ASTNode]: - return (self.operand,) - - -class BinaryOp(Enum): - """Binary operators.""" - - # Arithmetic - ADD = auto() - SUB = auto() - MUL = auto() - DIV = auto() - # Comparison - EQ = auto() - NE = auto() - LT = auto() - LE = auto() - GT = auto() - GE = auto() - # Logical - AND = auto() - OR = auto() - XOR = auto() - # Bitwise - LSHIFT = auto() - RSHIFT = auto() - - -class UnaryOp(Enum): - """Unary operators.""" - - NOT = auto() - NEG = auto() -``` - -### Gate Kinds - -```python -class GateKind(Enum): - """All supported gate types.""" - - # Single-qubit Paulis - X = auto() - Y = auto() - Z = auto() - # Hadamard - H = auto() - # Phase gates - S = auto() - Sdg = auto() - T = auto() - Tdg = auto() - # Square root gates - SX = auto() - SY = auto() - SZ = auto() - SXdg = auto() - SYdg = auto() - SZdg = auto() - # Rotation gates (parameterized) - RX = auto() - RY = auto() - RZ = auto() - # Two-qubit gates - CX = auto() - CY = auto() - CZ = auto() - CH = auto() - # Two-qubit rotations - SXX = auto() - SYY = auto() - SZZ = auto() - SXXdg = auto() - SYYdg = auto() - SZZdg = auto() - RZZ = auto() - # Face rotations - F = auto() - Fdg = auto() - F4 = auto() - F4dg = auto() - - @property - def arity(self) -> int: - """Number of qubit arguments.""" - two_qubit = { - GateKind.CX, - GateKind.CY, - GateKind.CZ, - GateKind.CH, - GateKind.SXX, - GateKind.SYY, - GateKind.SZZ, - GateKind.SXXdg, - GateKind.SYYdg, - GateKind.SZZdg, - GateKind.RZZ, - } - return 2 if self in two_qubit else 1 - - @property - def is_parameterized(self) -> bool: - """Whether this gate takes angle parameters.""" - return self in {GateKind.RX, GateKind.RY, GateKind.RZ, GateKind.RZZ} -``` - -### Type Expressions - -```python -@dataclass(frozen=True) -class TypeExpr(ASTNode): - """Type expression for return types and declarations.""" - - pass - - -@dataclass(frozen=True) -class QubitType(TypeExpr): - """Single qubit type.""" - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_qubit_type(self) - - -@dataclass(frozen=True) -class BitType(TypeExpr): - """Single classical bit type.""" - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_bit_type(self) - - -@dataclass(frozen=True) -class ArrayType(TypeExpr): - """Array type with element type and size.""" - - element: TypeExpr - size: int - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_array_type(self) - - def children(self) -> Sequence[ASTNode]: - return (self.element,) - - -@dataclass(frozen=True) -class AllocatorType(TypeExpr): - """Qubit allocator type with capacity.""" - - capacity: int - - def accept(self, visitor: ASTVisitor[T]) -> T: - return visitor.visit_allocator_type(self) -``` - ---- - -## Visitor Protocol - -```python -from typing import TypeVar, Protocol - -T = TypeVar("T") - - -class ASTVisitor(Protocol[T]): - """Protocol for AST visitors.""" - - # Program structure - def visit_program(self, node: Program) -> T: ... - def visit_allocator_decl(self, node: AllocatorDecl) -> T: ... - def visit_register_decl(self, node: RegisterDecl) -> T: ... - - # Statements - def visit_gate(self, node: GateOp) -> T: ... - def visit_prepare(self, node: PrepareOp) -> T: ... - def visit_measure(self, node: MeasureOp) -> T: ... - def visit_assign(self, node: AssignOp) -> T: ... - def visit_barrier(self, node: BarrierOp) -> T: ... - def visit_comment(self, node: CommentOp) -> T: ... - def visit_return(self, node: ReturnOp) -> T: ... - - # Control flow - def visit_if(self, node: IfStmt) -> T: ... - def visit_while(self, node: WhileStmt) -> T: ... - def visit_for(self, node: ForStmt) -> T: ... - def visit_repeat(self, node: RepeatStmt) -> T: ... - def visit_parallel(self, node: ParallelBlock) -> T: ... - - # References - def visit_slot_ref(self, node: SlotRef) -> T: ... - def visit_bit_ref(self, node: BitRef) -> T: ... - - # Expressions - def visit_literal(self, node: LiteralExpr) -> T: ... - def visit_var(self, node: VarExpr) -> T: ... - def visit_bit_expr(self, node: BitExpr) -> T: ... - def visit_binary(self, node: BinaryExpr) -> T: ... - def visit_unary(self, node: UnaryExpr) -> T: ... - - # Types - def visit_qubit_type(self, node: QubitType) -> T: ... - def visit_bit_type(self, node: BitType) -> T: ... - def visit_array_type(self, node: ArrayType) -> T: ... - def visit_allocator_type(self, node: AllocatorType) -> T: ... - - -class BaseVisitor(Generic[T]): - """Base visitor with default traversal behavior.""" - - def visit(self, node: ASTNode) -> T: - """Dispatch to appropriate visit method.""" - return node.accept(self) - - def visit_children(self, node: ASTNode) -> list[T]: - """Visit all children and collect results.""" - return [self.visit(child) for child in node.children()] - - # Default implementations that just visit children - def visit_program(self, node: Program) -> T: - self.visit_children(node) - return self.default_result() - - # ... etc for all node types ... - - def default_result(self) -> T: - """Default result when no specific handling.""" - return None # type: ignore -``` - ---- - -## Example: AST for QEC Program - -```python -# The SLR code: -# def main(): -# base = QAlloc(17) -# data = base.child(9) -# ancilla = base.child(8) -# data.prepare_all() -# ancilla.prepare_all() -# H(data[0]) -# CX(data[0], data[1]) -# Measure(ancilla) > syndrome - -# As AST: -program = Program( - name="main", - allocator=AllocatorDecl(name="base", capacity=17), - declarations=( - AllocatorDecl(name="data", capacity=9, parent="base"), - AllocatorDecl(name="ancilla", capacity=8, parent="base"), - RegisterDecl(name="syndrome", size=8), - ), - body=( - PrepareOp(allocator="data"), - PrepareOp(allocator="ancilla"), - GateOp( - gate=GateKind.H, - targets=(SlotRef("data", 0),), - ), - GateOp( - gate=GateKind.CX, - targets=(SlotRef("data", 0), SlotRef("data", 1)), - ), - MeasureOp( - targets=tuple(SlotRef("ancilla", i) for i in range(8)), - results=tuple(BitRef("syndrome", i) for i in range(8)), - ), - ), -) -``` - ---- - -## Integration with QAlloc - -The AST is designed to work seamlessly with the QAlloc system: - -### Allocator Hierarchy in AST - -```python -# Parent-child relationships are explicit -AllocatorDecl(name="base", capacity=100) -AllocatorDecl(name="data", capacity=7, parent="base") -AllocatorDecl(name="ancilla", capacity=6, parent="base") -``` - -### Slot State Validation - -The `QubitStateValidator` can work directly on the AST: - -```python -class ASTStateValidator(BaseVisitor[None]): - """Validate qubit states on AST.""" - - def __init__(self): - self.slot_states: dict[tuple[str, int], SlotState] = {} - self.violations: list[StateViolation] = [] - - def visit_prepare(self, node: PrepareOp) -> None: - # Mark slots as prepared - if node.slots is None: - # prepare_all - need allocator capacity - ... - else: - for slot in node.slots: - self.slot_states[(node.allocator, slot)] = SlotState.PREPARED - - def visit_gate(self, node: GateOp) -> None: - # Validate all targets are prepared - for target in node.targets: - state = self.slot_states.get((target.allocator, target.index), SlotState.UNPREPARED) - if state == SlotState.UNPREPARED: - self.violations.append(StateViolation(...)) - - def visit_measure(self, node: MeasureOp) -> None: - # Mark slots as unprepared - for target in node.targets: - self.slot_states[(target.allocator, target.index)] = SlotState.UNPREPARED -``` - ---- - -## Conversion Functions - -### From Current SLR to AST - -```python -def slr_to_ast(block: SLRBlock) -> Program: - """Convert current SLR block to AST.""" - converter = SLRToASTConverter() - return converter.convert(block) - - -class SLRToASTConverter: - """Converts SLR objects to AST nodes.""" - - def convert(self, block: SLRBlock) -> Program: - declarations = [] - body = [] - - # Convert variables - for var in block.vars: - declarations.append(self.convert_var(var)) - - # Convert operations - for op in block.ops: - body.append(self.convert_op(op)) - - return Program( - name=getattr(block, "block_name", "main"), - allocator=None, # Legacy mode - no base allocator - declarations=tuple(declarations), - body=tuple(body), - ) - - def convert_var(self, var) -> Declaration: - if isinstance(var, QReg): - # Convert to legacy allocator-like declaration - return AllocatorDecl(name=var.sym, capacity=var.size) - elif isinstance(var, CReg): - return RegisterDecl(name=var.sym, size=var.size, is_result=var.result) - elif isinstance(var, QAlloc): - return AllocatorDecl( - name=var.name, - capacity=var.capacity, - parent=var.parent.name if var.parent else None, - ) - # ... etc - - def convert_op(self, op) -> Statement: - op_name = type(op).__name__ - - if op_name in GATE_NAMES: - return self.convert_gate(op) - elif op_name == "Measure": - return self.convert_measure(op) - elif op_name in ("Prep", "Init", "Reset"): - return self.convert_prepare(op) - elif op_name == "If": - return self.convert_if(op) - # ... etc -``` - -### From AST to Current SLR - -```python -def ast_to_slr(program: Program) -> SLRBlock: - """Convert AST to current SLR objects for execution.""" - converter = ASTToSLRConverter() - return converter.convert(program) -``` - ---- - -## Code Generation from AST - -Each target gets a visitor: - -```python -class QASMGenerator(BaseVisitor[str]): - """Generate QASM from AST.""" - - def visit_program(self, node: Program) -> str: - lines = ["OPENQASM 2.0;", 'include "qelib1.inc";', ""] - - # Declarations - for decl in node.declarations: - lines.append(self.visit(decl)) - - lines.append("") - - # Body - for stmt in node.body: - lines.append(self.visit(stmt)) - - return "\n".join(lines) - - def visit_allocator_decl(self, node: AllocatorDecl) -> str: - return f"qreg {node.name}[{node.capacity}];" - - def visit_register_decl(self, node: RegisterDecl) -> str: - return f"creg {node.name}[{node.size}];" - - def visit_gate(self, node: GateOp) -> str: - gate_name = node.gate.name.lower() - targets = ", ".join(str(t) for t in node.targets) - if node.params: - params = ", ".join(str(p) for p in node.params) - return f"{gate_name}({params}) {targets};" - return f"{gate_name} {targets};" - - # ... etc - - -class GuppyGenerator(BaseVisitor[str]): - """Generate Guppy code from AST.""" - - # Similar structure, different output format - - -class HUGRGenerator(BaseVisitor[HUGRNode]): - """Generate HUGR from AST.""" - - # Returns HUGR IR nodes instead of strings -``` - ---- - -## Implementation Plan - -### Phase 1: Core AST Nodes - -1. Define all node dataclasses in `pecos/slr/ast/nodes.py` -2. Define visitor protocol in `pecos/slr/ast/visitor.py` -3. Implement `BaseVisitor` with default traversal - -### Phase 2: Conversion - -1. Implement `SLRToASTConverter` for current SLR → AST -2. Implement `ASTToSLRConverter` for AST → current SLR -3. Add tests for round-trip conversion - -### Phase 3: Analysis - -1. Port `QubitStateValidator` to work on AST -2. Add more analysis passes (unused variables, unreachable code, etc.) -3. Add pretty-printer for debugging - -### Phase 4: Code Generation - -1. Migrate QASM generator to use AST -2. Migrate Guppy generator to use AST -3. Add new generators as needed - -### Phase 5: DSL Integration - -1. Consider new DSL syntax that builds AST directly -2. Add builder pattern for programmatic AST construction -3. Integration with IDE tooling - ---- - -## Open Questions - -1. **Span tracking**: Should we track full spans (start + end) or just start locations? - -2. **Error recovery**: Should AST support partial/invalid trees for better error reporting? - -3. **Macro expansion**: How to handle QEC library blocks (Steane, etc.) that expand to multiple operations? - -4. **Metadata**: What additional metadata should nodes carry (e.g., optimization hints)? - -5. **Serialization**: Should AST be serializable to JSON/protobuf for tooling? - ---- - -## Summary - -The SLR AST provides: - -- **Clean structure**: Immutable, typed nodes with uniform interface -- **Easy analysis**: Visitor pattern for traversal and transformation -- **QAlloc integration**: First-class support for allocator hierarchy and slot states -- **Multi-target codegen**: One AST → QASM, Guppy, HUGR, etc. -- **Backward compatibility**: Conversion to/from current SLR objects diff --git a/design/proposals/slr-qubit-allocators.md b/design/proposals/slr-qubit-allocators.md deleted file mode 100644 index 0923e05f7..000000000 --- a/design/proposals/slr-qubit-allocators.md +++ /dev/null @@ -1,730 +0,0 @@ -# SLR Qubit Allocator Proposal - - - -## Status - -**Design decisions finalized.** Ready for implementation. - ---- - -## Motivation - -SLR needs to bridge two different models of qubit management: - -1. **QASM model**: Static registers declared upfront (`qreg q[5];`), all qubits exist from program start -2. **Guppy model**: Dynamic allocation with linear types (`q = qubit()`), qubits appear on demand - -Both have drawbacks: -- QASM's static registers lack ownership semantics and lifecycle tracking -- Guppy's dynamic allocation feels disconnected from physical hardware constraints ("qubits from nowhere") - -### The Allocator Model - -Inspired by Zig's allocator pattern and NASA's Power of 10 rules (particularly Rule 3: no dynamic allocation after initialization), we propose a hierarchical qubit allocator model that: -- Grounds allocation in physical resource constraints (total qubit budget declared upfront) -- Provides explicit ownership and natural scoping -- Tracks qubit slot states (unprepared vs prepared) -- Maintains array/register-oriented access patterns (effectively implementing QRegs) -- Enables compiler optimizations through abstracted physical identity - -### NASA Power of 10 Alignment - -| Power of 10 Rule | Allocator Model | -|------------------|-----------------| -| Rule 3: No dynamic allocation after init | Base allocator declares total capacity in `main` | -| Rule 6: Smallest possible scope | Child allocators scoped to functions/blocks | -| Rule 2: Fixed loop bounds | Allocator capacity is bounded and known | -| Predictability | All resource usage visible from `main` | - ---- - -## Core Concepts - -### 1. Base Allocator - -Every program declares a base allocator in `main` representing the total physical qubit capacity: - -```python -def main(): - base = QAlloc(capacity=100) # "I have 100 physical qubits" - - # All other allocators derive from this - data = base.child(7) - ancilla = base.child(6) - - run_qec(data, ancilla) -``` - -This is the root of all qubit ownership. It represents the actual hardware constraint. Functions that need qubits receive allocators (or children thereof) as parameters. - -### 2. Child Allocators (Hierarchical Ownership) - -Any allocator can create child allocators that reserve slots from its capacity: - -```python -base = QAlloc(100) - -# First level partitioning -data = base.child(7) # Reserve 7 slots for data -ancilla = base.child(6) # Reserve 6 slots for ancilla -# base now has 87 available - -# Nested partitioning - any allocator can have children -workspace = ancilla.child(2) # Borrow 2 from ancilla -# ancilla now has 4 available -``` - -**Key properties:** -- Child allocators exclusively reserve slots from their parent -- Parent cannot use reserved slots until child releases them -- Children can create their own children (unlimited depth) -- Natural scoping: unreturned allocators automatically release to parent - -### 3. Slots and Qubit Association - -An allocator has N **slots**. Each slot is in one of two states: - -``` -┌─────────────┐ -│ unprepared │ ← Not ready for gates (initial state, or after measurement) -└──────┬──────┘ - │ prepare() ← Request qubit, associate with slot, initialize to |0⟩ - ▼ -┌─────────────┐ -│ prepared │ ← Ready for gates -└──────┬──────┘ - │ measure() - ▼ -┌─────────────┐ -│ unprepared │ ← Back to unprepared -└─────────────┘ -``` - -Two states, not three. Whether a slot has "never been used" or "was measured" doesn't matter - both are **unprepared** and require `prepare()` before gates. - -**Key insight**: `prepare()` means "request a qubit to be associated with this slot and prepared for use." The slot becomes usable. After measurement, the slot returns to unprepared. - -**Rules (enforced at compile time):** -- Gates can only be applied to **prepared** slots → compile error if unprepared -- Measurement transitions slots to **unprepared** -- Slots can be prepared individually or in batches at different times - -### 4. Slot-Based Access (Not Physical Identity) - -Qubits are accessed through their allocator via slot indices: - -```python -ancilla = base.child(4) -ancilla.prepare(0, 1) # Prepare slots 0 and 1 - -H(ancilla[0]) # Apply H to slot 0 -CNOT(ancilla[0], ancilla[1]) # CNOT between slots 0 and 1 -``` - -**Important**: `ancilla[0]` refers to "slot 0 in the ancilla allocator" - not a fixed physical qubit. After measure + prepare cycles, the physical qubit backing slot 0 may change. The compiler manages the mapping. - -```python -ancilla.prepare_all() -# ancilla[0] → physical qubit 42 - -Measure(ancilla) -ancilla.prepare_all() -# ancilla[0] → might now be physical qubit 37 (compiler's choice) -``` - -This abstraction enables: -- Qubit recycling and reuse optimizations -- Routing around defective qubits -- Connectivity-aware mapping - -The programmer thinks in logical slots; the compiler handles physical mapping. - -### 5. Ownership and Natural Scoping - -Allocators follow ownership rules similar to Zig: - -```python -def syndrome_round(ancilla: QAlloc[6]) -> Bits: - ancilla.prepare_all() - # ... syndrome extraction ... - return Measure(ancilla) - # ancilla NOT returned → consumed → released to parent - - -def apply_logical_gate(data: QAlloc[7]) -> QAlloc[7]: - # ... apply gate ... - return data # returned → caller retains ownership -``` - -**Scoping rules:** -- If an allocator is not returned from a function/block, it is automatically released -- Released resources flow back to the parent allocator -- No explicit `free()` or `release()` needed - scope handles it - ---- - -## API Design - -### QAlloc Class - -```python -class QAlloc[N]: - """ - A qubit allocator managing N qubit slots. - - Type parameter N is the capacity (known at compile time for type checking, - but can also be runtime-determined). - """ - - # --- Creation --- - - def __init__(self, capacity: int): - """Create a base allocator with given capacity.""" - ... - - def child(self, size: int) -> QAlloc: - """ - Create a child allocator with `size` slots. - - Reserves `size` qubits from this allocator's available pool. - Raises if insufficient capacity available. - """ - ... - - # --- Lifecycle Operations --- - - def prepare(self, *indices: int) -> None: - """Prepare specific slots (unprepared → prepared).""" - ... - - def prepare_all(self) -> None: - """Prepare all slots in this allocator.""" - ... - - # --- Access --- - - def __getitem__(self, index: int) -> QubitRef: - """ - Access slot `index` for use in gates. - - Returns a QubitRef that can be passed to gate operations. - The qubit must be in 'prepared' state. - """ - ... - - # --- Information --- - - @property - def capacity(self) -> int: - """Total number of slots in this allocator.""" - ... - - @property - def available(self) -> int: - """Number of slots not reserved by children.""" - ... - - def state(self, index: int) -> SlotState: - """Get the state of a specific slot (unprepared or prepared).""" - ... -``` - -### QubitRef (Reference to a Slot) - -```python -class QubitRef: - """ - A reference to a qubit slot in an allocator. - - Used as arguments to gate operations. Not a standalone qubit - - always tied to its parent allocator. - """ - - allocator: QAlloc - index: int -``` - -### SlotState Enum - -```python -class SlotState(Enum): - UNPREPARED = "unprepared" # Not ready for gates (initial or post-measurement) - PREPARED = "prepared" # Ready for gate operations -``` - -Two states only. Simple. - -### Gate Operations - -Gates accept `QubitRef` arguments: - -```python -# Single qubit gates -H(alloc[0]) -X(alloc[1]) -Rz(alloc[2], angle=0.5) - -# Two qubit gates -CNOT(alloc[0], alloc[1]) -CZ(data[0], ancilla[0]) # Can span different allocators - -# Measurement (transitions to unprepared) -result = Measure(alloc[0]) # Single qubit -results = Measure(alloc) # All qubits in allocator -results = Measure(alloc[0:3]) # Slice of allocator -``` - ---- - -## Edge Cases and Considerations - -### 1. Cross-Allocator Entanglement - -**Scenario**: Qubits from different allocators become entangled. - -```python -data = base.child(7) -ancilla = base.child(6) - -data.prepare_all() -ancilla.prepare_all() - -# Entangle across allocators -CNOT(data[0], ancilla[0]) -``` - -**Decision**: Allowed. Allocators manage ownership and slot lifecycle, not entanglement tracking. If `ancilla` is released while entangled with `data`, the slots return to the parent (unprepared). No compiler warning needed - we're not tracking entanglement. - -### 2. Partial Measurement - -**Scenario**: Only some slots in an allocator are measured. - -```python -ancilla = base.child(4) -ancilla.prepare_all() - -# Measure only slots 0 and 1 -result = Measure(ancilla[0], ancilla[1]) - -# ancilla[0], ancilla[1] are now unprepared -# ancilla[2], ancilla[3] are still prepared -``` - -**Resolution**: The allocator tracks per-slot state. This is fully supported. - -### 3. Capacity Exhaustion - -**Scenario**: Requesting more qubits than available. - -```python -base = QAlloc(10) -a = base.child(6) -b = base.child(6) # ERROR: only 4 available -``` - -**Resolution**: -- **Compile-time**: If sizes are known statically, this is a compile error -- **Runtime**: Raises an exception (e.g., `AllocationError`) - -The type system can help: `QAlloc[N]` carries capacity information. - -### 4. Returning Partial Allocators - -**Scenario**: Function receives an allocator, creates children, returns some. - -```python -def split_and_process(alloc: QAlloc[10]) -> QAlloc[3]: - a = alloc.child(3) - b = alloc.child(7) - - process(b) # b consumed (not returned) - - return a # Only a returned - COMPILE ERROR -``` - -**Decision**: Must return parent OR all children. Enforced at compile time. - -If you create children from a received allocator, you must either: -1. Return the parent allocator (children are released back to it) -2. Return ALL children (parent is consumed, all resources accounted for) - -This ensures clear resource contracts and prevents orphaned slots. - -```python -# Valid: return parent -def process_and_return(alloc: QAlloc[10]) -> QAlloc[10]: - child = alloc.child(5) - use(child) # child released back to alloc - return alloc - - -# Valid: return all children -def split_evenly(alloc: QAlloc[10]) -> tuple[QAlloc[5], QAlloc[5]]: - a = alloc.child(5) - b = alloc.child(5) - return a, b # alloc consumed, all slots accounted for -``` - -### 5. Conditional Allocation - -**Scenario**: Allocation inside conditional blocks. - -```python -base = QAlloc(10) - -if condition: - extra = base.child(5) - extra.prepare_all() - # ... use extra ... - # extra released at end of block -else: - pass # no allocation -``` - -**Resolution**: This is fine. The allocation is scoped to the if-block. After the block, resources are back in `base`. Both branches end with `base` having the same available capacity. - -### 6. Allocation in Loops - -**Scenario**: Creating allocators inside loops. - -```python -base = QAlloc(10) - -for round in range(1000): - ancilla = base.child(4) - ancilla.prepare_all() - syndrome = Measure(ancilla) - # ancilla released, back to base - - # Next iteration can allocate again -``` - -**Resolution**: This is a primary use case. Each iteration allocates, uses, and releases. The pool is recycled. - -### 7. Escaping References (Zig-inspired) - -**Scenario**: Storing a `QubitRef` beyond the allocator's lifetime. - -```python -stored_ref = None - - -def bad_function(alloc: QAlloc[5]): - global stored_ref - alloc.prepare_all() - stored_ref = alloc[0] # Store reference - # alloc released at end - - -bad_function(base.child(5)) -H(stored_ref) # ERROR: dangling reference -``` - -**Decision**: `QubitRef` is ephemeral, like Zig slices/pointers into allocator memory. - -In Zig, when you get memory from an allocator, you get a slice that's valid only while the allocator owns that memory. Similarly, `QubitRef` is valid only while its allocator is alive. - -- `alloc[i]` creates a `QubitRef` for immediate use in gate operations -- `QubitRef` should not be stored in data structures or globals -- The compile-time analysis detects when a `QubitRef` escapes its allocator's scope -- If used after allocator release: compile error (if detectable) or runtime error - -### 8. Allocator Merging - -**Scenario**: Combining two sibling allocators. - -```python -base = QAlloc(10) -a = base.child(3) -b = base.child(3) - -# Can we merge a and b into a single allocator of 6? -merged = merge(a, b) # ??? -``` - -**Resolution**: Not supported in initial design. If you need a combined view: -- Release both back to parent -- Allocate a new child of desired size - -Merging adds complexity (different qubit states, index remapping). YAGNI for now. - -### 9. Slicing Allocators - -**Scenario**: Creating a view into part of an allocator. - -```python -data = base.child(7) -first_three = data[0:3] # Is this a new allocator or just refs? -``` - -**Resolution**: Two options: - -**Option A**: Slicing returns a tuple of `QubitRef` -```python -first_three = (data[0], data[1], data[2]) # Just refs -``` - -**Option B**: Slicing creates a child allocator (view) -```python -first_three = data.slice(0, 3) # New child allocator -``` - -**Recommendation**: Option A for simplicity. Slicing is just syntactic sugar for multiple refs. Use explicit `child()` for ownership transfer. - -### 10. Classical Data - Do We Need Allocators? - -**Decision**: No. Keep `CReg` as-is. - -Classical data doesn't have: -- The same physical scarcity constraints -- Lifecycle states (bits don't need "preparation") -- The same ownership complexity - -Classical registers remain as simple `CReg` arrays. The allocator pattern is specifically for quantum resources. - -### 11. Interaction with Existing SLR Constructs - -The allocator model effectively implements `QReg` with additional semantics: - -| Current | New | -|---------|-----| -| `QReg("q", 5)` | `q = parent.child(5)` | -| `q[0]` (Qubit) | `q[0]` (QubitRef) | -| `Prep(q[0])` | `q.prepare(0)` | -| `Measure(q[0])` | `Measure(q[0])` (unchanged) | - -**Key difference**: Base allocator declared in main, passed to functions: - -```python -def main(): - base = QAlloc(100) # Declare capacity in main - - data = base.child(7) - ancilla = base.child(6) - - data.prepare_all() - ancilla.prepare_all() - - run_qec_rounds(data, ancilla) - - -def run_qec_rounds(data: QAlloc[7], ancilla: QAlloc[6]): - # Receives allocators as parameters - ... -``` - -This replaces the current pattern where `QReg` is declared inside `Block` classes. - ---- - -## Type System Integration - -### Static Capacity Tracking - -```python -QAlloc[N] # Allocator with capacity N - - -def syndrome_extraction(data: QAlloc[7], ancilla: QAlloc[6]) -> tuple[Bits, QAlloc[7]]: - # Type system knows: - # - data has 7 slots - # - ancilla has 6 slots - # - ancilla is consumed (not in return type) - # - data is returned (ownership transferred back) - ... -``` - -### Lowering to Target Formats - -| Target | Allocator Becomes | -|--------|-------------------| -| QASM 2.0 | `qreg` declarations with index mapping | -| QASM 3.0 | `qubit[N]` arrays | -| Guppy | `array[qubit, N]` with linear ownership | -| HUGR | Qubit allocation ops with region tracking | -| QIR | Qubit allocation intrinsics | - ---- - -## Implementation Plan - -### Phase 1: Core Data Structures - -1. Define `QAlloc` class with: - - Capacity tracking - - Child creation and management - - Per-slot state tracking (unprepared/prepared) - -2. Define `QubitRef` class as thin wrapper - -3. Define `SlotState` enum (two states: unprepared, prepared) - -### Phase 2: Integration with SLR Operations - -1. Modify gate classes to accept `QubitRef` -2. Add `prepare()` method/gate -3. Modify `Measure` to transition slots to unprepared -4. Update `Block` to require base allocator declaration - -### Phase 3: Code Generation Updates - -1. Update `SlrConverter` to handle allocator-based programs -2. Update QASM generator to map allocators to registers -3. Update Guppy generator to map allocators to arrays with linear semantics -4. Update resource planner to understand allocator hierarchy - -### Phase 4: Validation and Analysis - -1. Add compile-time checks for: - - Base allocator requirement - - Capacity overflow detection - - Lifecycle violations (gate on unprepared slot) - - Ownership violations (use after release) - -2. Add warnings for: - - Releasing entangled qubits - - Unused allocator capacity - -**Integration Points for State Checking:** - -The existing data flow analysis infrastructure can be leveraged: -- `DataFlowAnalyzer` (data_flow.py:37-354) - already tracks consumption and replacement -- `IRAnalyzer` (ir_analyzer.py:114) - integration point after `_integrate_data_flow()` -- `IRBuilder` (ir_builder.py:3078, 4137) - gate conversion with validation -- `ScopeManager` (scope_manager.py:27-145) - runtime state tracking - -A new `QubitStateValidator` module would: -1. Initialize from DataFlowAnalysis with all elements as "unprepared" -2. Mark elements as "prepared" when `Prep`/`Init`/`Reset` operations occur -3. Mark elements as "unprepared" when `Measure` operations occur -4. Validate that gates only operate on "prepared" elements - -### Phase 5: Documentation and Migration - -1. Document the allocator model -2. Provide migration guide from `QReg` to allocators -3. Update examples - ---- - -## Design Decisions Summary - -| Question | Decision | -|----------|----------| -| Slot states | Two: `unprepared` and `prepared` (no separate "dirty") | -| Prepare syntax | Method: `alloc.prepare(0, 1, 2)` or `alloc.prepare_all()` | -| Gate on unprepared slot | Compile-time error | -| Base allocator location | Declared in `main`, passed to functions | -| Returning allocators | Must return parent OR all children | -| Cross-allocator entanglement | Allowed, not tracked | -| Classical registers | Keep `CReg` as-is | -| QubitRef lifetime | Ephemeral, Zig-inspired (no escaping scope) | -| Philosophy | NASA Power of 10 inspired (no dynamic alloc after init) | - ---- - -## Implementation Decisions - -| Question | Decision | -|----------|----------| -| Migration | Dual support: `QReg` as alias/wrapper for `QAlloc` | -| Naming | `QAlloc` (follows `QReg`/`CReg` convention) | -| Prepare return | `void` - keeps refs ephemeral, allocator is source of truth | - ---- - -## Complete Example: QEC Round - -```python -def main(): - # Declare physical resource budget - base = QAlloc(capacity=17) - - # Partition into logical groupings - data = base.child(9) # 9 data qubits for surface code - ancilla = base.child(8) # 8 ancilla for syndrome extraction - - # Initialize data qubits - data.prepare_all() - encode_logical_zero(data) - - # Run QEC rounds - for round in range(100): - syndrome = extract_syndrome(data, ancilla) - if needs_correction(syndrome): - apply_correction(data, syndrome) - - # Final readout - result = decode_and_measure(data) - return result - - -def extract_syndrome(data: QAlloc[9], ancilla: QAlloc[8]) -> Bits: - """ - Extract syndrome without consuming data. - Ancilla is consumed (not returned). - """ - ancilla.prepare_all() - - # X stabilizers - for i in range(4): - H(ancilla[i]) - CNOT(ancilla[i], data[stabilizer_x_targets(i)]) - H(ancilla[i]) - - # Z stabilizers - for i in range(4): - CNOT(data[stabilizer_z_targets(i)], ancilla[4 + i]) - - # Measure all ancilla - slots become unprepared - syndrome = Measure(ancilla) - - # ancilla not returned → released back to caller's scope - # data returned implicitly via not being consumed - return syndrome - - -def encode_logical_zero(data: QAlloc[9]) -> QAlloc[9]: - """ - Encode logical |0⟩. Returns the data allocator. - """ - # data already prepared by caller - H(data[0]) - CNOT(data[0], data[1]) - # ... encoding circuit ... - return data # Ownership returned to caller - - -def decode_and_measure(data: QAlloc[9]) -> Bits: - """ - Decode and measure. Consumes the data allocator. - """ - # ... decoding circuit ... - result = Measure(data) - # data not returned → consumed - return result -``` - -### What This Demonstrates - -1. **Base in main**: `QAlloc(17)` declares total capacity upfront -2. **Child allocators as "registers"**: `data` and `ancilla` are like QRegs -3. **Slot preparation**: `prepare_all()` makes slots usable -4. **Natural consumption**: `ancilla` not returned from `extract_syndrome` → released -5. **Explicit return for ownership**: `encode_logical_zero` returns `data` to maintain ownership -6. **Loop reuse**: Each round re-prepares ancilla, reusing the same slots - ---- - -## Summary - -The qubit allocator model provides: - -- **Physical grounding**: Resources come from a declared capacity, not thin air -- **Hierarchical ownership**: Clear parent-child relationships with natural scoping -- **Lifecycle tracking**: Two states (unprepared/prepared) enforced at compile time -- **Slot abstraction**: Logical indices, not physical identity - enabling optimizations -- **Clean semantics**: Ownership rules similar to Rust/Zig for resource safety - -This bridges QASM's register model and Guppy's linear types while feeling more connected to physical hardware constraints. diff --git a/design/python-classical-interpreter-suspected-bugs.md b/design/python-classical-interpreter-suspected-bugs.md deleted file mode 100644 index ce8060449..000000000 --- a/design/python-classical-interpreter-suspected-bugs.md +++ /dev/null @@ -1,54 +0,0 @@ -# Python PhirClassicalInterpreter -- Suspected Bugs - -Found during the Rust reimplementation and fuzz testing. - -Bugs #1 and #2 are the same class of issue as -[PECOS-packages/PECOS#213](https://github.com/PECOS-packages/PECOS/issues/213): -PECOS dtype constructors reject values outside the type range instead of -masking/wrapping. PR #214 fixed the specific operator overload case but the -underlying dtype overflow issue remains. - -## 1. Overflow rejected for values that fit the register but not the dtype - -**Status:** FIXED (dtype constructors now truncate instead of rejecting) - -**Description:** `assign_int` converts the value through the PECOS dtype constructor (`dtype(val)`) before masking to register size. If the value exceeded the dtype's range, Python threw `OverflowError`. Fixed by changing dtype constructors to accept `i64` and truncate via cast. - ---- - -## 2. Bitwise NOT overflows when assigning cross-type - -**Status:** FIXED (dtype constructors now truncate instead of rejecting) - -**Description:** `~m` where `m` is `u32 size=1` produced `u32(4294967295)`. Assigning to an `i32` variable did `i32(4294967295)` which threw `OverflowError`. Fixed by the same dtype constructor change. - ---- - -## 3. `PhirModel.model_validate` rejects valid PHIR programs with `Result` cop - -**Confidence:** High (but in the `phir` pydantic model, not the interpreter itself) -**File:** `python/quantum-pecos/src/pecos/classical_interpreters/phir_classical_interpreter.py` -**Line:** 101-102 - -**Description:** When `phir_validate=True` (default), the interpreter validates programs through `PhirModel.model_validate()` from the `phir` pydantic package. This validator rejects the `Result` classical operation, which is a valid PECOS-specific extension used in many test programs. - -**Example:** Programs with `{"cop": "Result", "args": ["m"], "returns": ["c"]}` fail pydantic validation even though they execute correctly. - -**Impact:** Users must set `phir_validate=False` to run programs with `Result` operations when using the Python interpreter. The Rust interpreter's serde parser handles these correctly. - ---- - -## Design questions (not clear-cut bugs) - -### Signed types not masked to register size - -**File:** `python/quantum-pecos/src/pecos/classical_interpreters/phir_classical_interpreter.py` -**Line:** 345-349 - -`assign_int()` only masks unsigned types to the register's declared `size`. Signed types are stored at the full dtype width. The code has a comment: `# (only valid for unsigned data types)` -- suggesting this was a deliberate choice. - -The PHIR spec says "assigning 5 to a 2-bit variable stores only the lower 2 bits" with no unsigned-only qualifier, but there may be good reasons for treating signed types differently (sign-extension from narrow widths is lossy). - -### Shift by type width is a no-op - -`u32(1) << 32` gives `u32(1)` instead of `u32(0)`. The PECOS dtype uses native hardware shift semantics (shift amount modulo type width). This matches x86/ARM behavior but not mathematical semantics. Whether the PHIR spec expects hardware or mathematical shift behavior is unclear. diff --git a/design/rust-phir-classical-interpreter.md b/design/rust-phir-classical-interpreter.md deleted file mode 100644 index ebfd0c378..000000000 --- a/design/rust-phir-classical-interpreter.md +++ /dev/null @@ -1,298 +0,0 @@ -# Rust PhirClassicalInterpreter -- Drop-in Replacement Spec - -## Goal - -Build a Rust `PhirClassicalInterpreter` that is a drop-in replacement for the Python -`PhirClassicalInterpreter` in `HybridEngine`. The Python PHIR code is the spec -- the -Rust version must have identical behavior. - -Eventually we move to the full Rust sim() system, but this is the first step: replace -the Python classical interpreter internals while keeping the Python `HybridEngine` -orchestration. - -## Architecture - -``` -crates/pecos-phir-json/ -- Rust logic lives here (reuse existing internals) -python/pecos-rslib/ -- PyO3 wrapper lives here (new pyclass) -``` - -The Rust interpreter reuses existing components from `pecos-phir-json/src/v0_1/`: -- `ast.rs` -- PHIR JSON parsing -- `environment.rs` -- variable storage, bit ops, types -- `expression.rs` -- expression evaluation -- `operations.rs` -- classical op handling logic (adapt) - -The PyO3 layer in `pecos-rslib` exposes it as a `#[pyclass]` implementing the -`ClassicalInterpreterProtocol`. - -## Python Protocol - -From `python/quantum-pecos/src/pecos/protocols.py`, the interpreter must satisfy: - -```python -class ClassicalInterpreterProtocol(Protocol): - program: Any - foreign_obj: Any - phir_validate: bool - - def reset(self) -> None: ... - def init(self, program: str | dict | QuantumCircuit, foreign_obj: object | None = None) -> int: ... - def shot_reinit(self) -> None: ... - def execute(self, sequence: Sequence | None) -> Generator[list[QOp | MOp], Any, None]: ... - def receive_results(self, qsim_results: list[dict]) -> None: ... - def results(self, *, return_int: bool = True) -> dict: ... -``` - -Additional methods called by HybridEngine but not in the protocol: -```python -def add_cvar(self, cvar: str, dtype: type, size: int) -> None: ... -def result_bits(self, bits: Iterable, *, filter_private: bool = True) -> dict: ... -``` - -## Call Ordering in HybridEngine - -``` -INITIALIZATION: - outer = PhirClassicalInterpreter() - inner = PhirClassicalInterpreter() - inner.phir_validate = outer.phir_validate - - num_qubits = outer.init(program, foreign_object) - inner.init(program, foreign_object) # same program - machine.init(num_qubits) - -PER-SHOT: - outer.shot_reinit() - inner.shot_reinit() - for i in range(num_qubits): - inner.add_cvar(f"__q{i}__", pc.dtypes.i64, 1) # private qubit vars - - EXECUTION LOOP: - for buffered_ops in outer.execute(outer.program.ops): - noisy_ops = op_processor.process(buffered_ops) - measurements.clear() - for noisy_qops in inner.execute(noisy_ops): - temp_meas = qsim.run(noisy_qops) - inner.receive_results(temp_meas) - measurements.extend(temp_meas) - transmit_meas = inner.result_bits(measurements) - outer.receive_results([transmit_meas]) - - RESULTS: - shot_results = outer.results(return_int=return_int) -``` - -## Data Flow - -``` -PHIR JSON str/dict - | - v -outer.init() --> parse JSON, validate, build internal AST, init env - | return num_qubits - v -outer.execute(program.ops) - | - | yields: list[QOp | MOp] (batches ending at measurements) - v -op_processor.process(buffered_ops) - | - | returns: list[QOp] (noisy operations) - v -inner.execute(noisy_ops) - | - | yields: list[QOp] - v -qsim.run(noisy_qops) - | - | returns: list[dict] e.g. [{("m", 0): 1, ("m", 1): 0}] - v -inner.receive_results(temp_meas) --> stores via assign_int - | -inner.result_bits(measurements) --> extracts bits, filters __private__ vars - | - | returns: dict[(str, int), int] - v -outer.receive_results([transmit_meas]) --> stores via assign_int - | -outer.results(return_int=...) - | - | returns: dict[str, int_or_bitstring] -``` - -## What `execute()` Yields - -`execute()` is a generator/iterator. It yields `list[QOp | MOp]`. - -Behavior: -- Walks the op list, recursively flattening SeqBlock and evaluating IfBlock conditions -- Buffers QOps and MOps -- Executes COps inline (never yielded) -- Yields the buffer when a measurement QOp is encountered (name in {"measure Z", "Measure", "Measure +Z"}) -- Yields remaining buffer at end of program -- Classical ops (assignment, Result mapping, FFCall) are handled during the walk - -### QOp Fields (what consumers read) - -``` -name: str # e.g. "H", "Measure", "RZ" -sim_name: str # resolved name for simulator -args: list[int] | list[tuple] # qubit IDs -returns: list | None # measurement targets, e.g. [["m", 0], ["m", 1]] -metadata: dict | None # includes "angle", "angles", "var_output" -angles: tuple[float, ...] | None # rotation angles in radians -``` - -Fields read by QuantumSimulator: `sim_name`, `args`, `metadata`, `returns` -Fields read by GenericOpProc: only `isinstance()` checks (QOp vs MOp routing) - -### MOp Fields - -``` -name: str -args: list | None -returns: list | None -metadata: dict | None # may contain "duration" -``` - -## The Generator Problem - -Python `execute()` is a coroutine -- yields batches, caller runs quantum sim, feeds -measurements back via `receive_results()`, then execution resumes. Conditional branches -may depend on those measurement results. - -**Solution: PyO3 iterator class.** A `#[pyclass]` that holds interpreter state and -advances to the next yield point on each `__next__()`. The Rust struct holds program -state, and each `__next__` call processes ops until the next measurement batch. - -## Dual Interpreter Pattern - -HybridEngine uses TWO interpreter instances: - -**Outer interpreter:** -- Drives the full program -- Has only program-declared variables -- Receives filtered measurement bits from inner via `receive_results()` - -**Inner interpreter:** -- Processes noisy ops from error model -- Gets extra `__q{i}__` private vars via `add_cvar()` (one per qubit, i64, size 1) -- `result_bits()` filters out `__`-prefixed vars when transmitting back - -Both use the same code, same class. The inner just handles a flat list of QOps -(no blocks to flatten) and has extra private vars. - -## Method Details - -### `init(program, foreign_obj) -> int` - -1. Parse program: JSON string -> dict, or accept dict directly -2. Validate format ("PHIR/JSON" or "PHIR") and version (< 0.2.0) -3. Optionally validate against PHIR schema (if `phir_validate` is True) -4. Build internal AST / operation list -5. Extract variable definitions, initialize environment (all vars to 0) -6. Check foreign function calls against foreign object -7. Return num_qubits - -### `shot_reinit()` - -Reset all variable values to 0. Keep variable definitions. - -### `execute(sequence) -> Iterator[list[QOp | MOp]]` - -Walk ops, flatten blocks, execute classical ops, yield quantum op batches. -See "What execute() Yields" above. - -### `receive_results(qsim_results: list[dict])` - -Each dict maps `cvar` or `(cvar, idx)` to a value. -For each key/value, calls `assign_int(key, value)`. - -### `result_bits(bits, filter_private=True) -> dict` - -`bits` is a list of measurement dicts from qsim.run(). -Iterates all (cvar, bit_idx) pairs, filters out `__`-prefixed vars, -returns `{(cvar, bit_idx): self.get_bit(cvar, bit_idx)}`. - -Important: reads from own env (after receive_results), not from input. - -### `results(return_int=True) -> dict` - -Returns ALL variables in csym2id. -- return_int=True: values are integers -- return_int=False: values are zero-padded binary strings ("{:0{width}b}") - -### `add_cvar(cvar, dtype, size)` - -Dynamically add a new classical variable after init. Used by HybridEngine -for the inner interpreter's private qubit vars. - -### `assign_int(cvar, val)` - -Assign integer value to variable or specific bit. -- `cvar` is a string: assign whole variable -- `cvar` is (string, int): assign to bit at index - -## Name Resolver - -`sim_name_resolver(qop)` translates PHIR gate names to simulator names: -- `RZZ(0.0)` -> `"I"` -- `RZZ(pi/2)` -> `"SZZ"` -- `RZZ(3pi/2)` -> `"SZZdg"` -- `RZ(angle)` -> tries clifford match -- `R1XY(angles)` -> tries clifford match -- Otherwise returns `qop.name` - -Applied during PHIR parsing when building QOp objects. The Rust side needs this -for yielded QOps to have correct `sim_name` values. - -## Foreign Function Calls - -FFCalls are COps handled during `execute()` -- never yielded. The foreign object -is a Python object implementing `ForeignObjectProtocol`: - - def exec(func_name: str, args: Sequence) -> tuple | int - -The Rust side must call back into this Python object for FFCalls. This requires -holding a `Py` reference. - -## Edge Cases - -- **Empty programs**: `execute([])` yields nothing. `results()` returns `{}` -- **No measurements**: buffer yielded at end (if non-empty). No receive_results() calls. -- **Only classical ops**: all handled inline. Nothing yielded. results() has computed values. -- **"Result" cop**: maps internal register to external name, copies value, creates dest var if needed. - -## What Exists vs What Needs Building - -### Reuse from `pecos-phir-json/src/v0_1/`: - -| Component | File | Notes | -|-----------|------|-------| -| PHIR JSON parsing | `ast.rs` | Complete | -| Variable storage | `environment.rs` | Complete -- DataType, TypedValue, Environment | -| Expression eval | `expression.rs` | Complete -- all operators | -| Classical ops | `operations.rs` | Adapt -- different interface needed | -| Block flattening | `block_iterative_executor.rs` | Adapt -- yield pattern differs | - -### New code needed: - -| Component | Location | Description | -|-----------|----------|-------------| -| Rust interpreter struct | `pecos-phir-json` | State machine wrapping existing internals | -| PyO3 wrapper class | `pecos-rslib` | `#[pyclass]` with protocol methods | -| PyO3 iterator | `pecos-rslib` | `__iter__`/`__next__` for execute() generator | -| QOp/MOp pyclass | `pecos-rslib` | Lightweight attribute bags for yielded ops | -| Name resolver | `pecos-phir-json` | Port of sim_name_resolver | -| result_bits() | `pecos-phir-json` | Bit extraction with private var filtering | -| receive_results() | `pecos-phir-json` | Handle list[dict] format | -| results() | `pecos-phir-json` | Return dict with return_int flag | - -## Validation Strategy - -The Rust interpreter must produce identical results to the Python one. Test by: -1. Running existing PHIR test programs through both interpreters -2. Comparing shot-by-shot results -3. Testing edge cases (empty programs, no measurements, only classical ops) -4. Testing the dual-interpreter pattern (outer + inner with private vars) diff --git a/docs/concepts/clifford-rz-simulator.md b/docs/concepts/clifford-rz-simulator.md index b3e1a3320..d6e3f53c0 100644 --- a/docs/concepts/clifford-rz-simulator.md +++ b/docs/concepts/clifford-rz-simulator.md @@ -1,6 +1,6 @@ # Clifford+RZ Simulator -The `CliffordRz` simulator represents quantum states as weighted sums of stabilizer +The `StabVec` simulator represents quantum states as weighted sums of stabilizer states using the CH-form representation from Bravyi et al. ([arXiv:1808.00128](https://arxiv.org/abs/1808.00128)). This enables efficient simulation of circuits with many Clifford gates and a moderate number of RZ rotations. @@ -68,7 +68,7 @@ tableaux lack. ## Sum-over-Cliffords decomposition -The `CliffordRz` simulator represents the full quantum state as: +The `StabVec` simulator represents the full quantum state as: ``` |psi> = sum_k alpha_k |phi_k> @@ -186,14 +186,14 @@ Default threshold: 1e-8. This trades exactness for keeping T manageable. When T exceeds a threshold (default: 2048), measurement uses O(T) term sampling instead of exact O(T^2) pairwise inner products. -## When to use CliffordRz +## When to use StabVec | Scenario | Best approach | |----------------------------------------------|--------------------------------------------------------------------------------| | Pure Clifford, no branching, pure depolarizing noise | DEM sampling (detector error model -- fastest, but limited to this restricted case) | | Pure Clifford circuits (general) | SparseStab (single tableau, O(n^2) worst case, typically less due to sparsity) | | Few qubits, arbitrary gates | StateVec (full 2^n vector) | -| Many qubits, mostly Clifford, some rotations | CliffordRz | +| Many qubits, mostly Clifford, some rotations | StabVec | | Deep circuits with many rotations | StateVec or cuQuantum (term count explodes) | For pure Clifford QEC circuits without branching or conditional logic, and with only @@ -202,7 +202,7 @@ entirely and is significantly faster. However, stabilizer tableaux like SparseSt full state simulators that handle the general case -- branching, conditional operations, arbitrary Clifford circuits, and complex noise models. -The sweet spot for CliffordRz is large qubit counts with circuits dominated by Clifford +The sweet spot for StabVec is large qubit counts with circuits dominated by Clifford gates and a moderate number of non-Clifford rotations -- typical of error correction circuits with T gates or variational circuits with few parameterized layers. diff --git a/docs/concepts/decoder-architecture.md b/docs/concepts/decoder-architecture.md new file mode 100644 index 000000000..b54edd498 --- /dev/null +++ b/docs/concepts/decoder-architecture.md @@ -0,0 +1,205 @@ +# Decoder Architecture + +PECOS provides a layered decoder architecture for quantum error correction, +from simple memory experiments to logical algorithms with transversal gates +and real-time streaming decode. + +## Design Principles + +- **Composable**: any MWPM-compatible decoder can be used as an inner decoder +- **Budget-aware**: automatically adapts window size and overlap based on hardware timing constraints +- **Streaming**: accepts syndrome data round-by-round for real-time operation +- **Frame-tracking**: propagates Pauli corrections through transversal gate boundaries + +## Decoder Layers + +The architecture is layered, with each layer adding capability: + +``` +Layer 1: Inner Decoder (MWPM) + PyMatching, Fusion Blossom, Union-Find, ... + Input: graphlike DEM + syndrome + Output: observable correction bitmask + +Layer 2: Observable Subgraph Decoder (OSD) + Decomposes transversal-gate circuits into per-observable graphlike subgraphs + Input: full DEM (may have hyperedges) + syndrome + spatial coordinates + Output: observable correction bitmask + +Layer 3: Logical Algorithm Decoder + Adds frame propagation across transversal gate boundaries + Input: algorithm descriptor (segments + boundary gates) + syndrome + Output: correction at each decision point + +Layer 4: Logical Circuit Decoder (budget-aware) + Selects decode strategy based on hardware timing budget + Input: algorithm descriptor + budget + syndrome stream + Output: real-time corrections +``` + +## Layer 1: Inner Decoders + +Any decoder implementing the `ObservableDecoder` trait: + +| Decoder | Type | DEM Support | Accuracy | Speed | +|---------|------|-------------|----------|-------| +| PyMatching | MWPM | graphlike | baseline | fast | +| Fusion Blossom | MWPM | graphlike | ~baseline | fast (parallel) | +| Tesseract | A* search | any (hyperedges) | best | medium | +| BP+OSD | LDPC | any | good | slow | +| Union-Find | cluster | graphlike | good | fastest | +| MWPF | matching | graphlike | best | slow | + +MWPM decoders require **graphlike** (decomposed) DEMs where every mechanism +touches at most 2 detectors. Non-MWPM decoders can handle hyperedges directly. + +Use `decoder_dem_requirement(decoder_type)` to query what a decoder needs: + +```python +from pecos_rslib.qec import decoder_dem_requirement + +decoder_dem_requirement("pymatching") # "graphlike" +decoder_dem_requirement("tesseract") # "any" +``` + +## Layer 2: Observable Subgraph Decoder (OSD) + +**Problem**: Transversal gates (H, CX) create hyperedge mechanisms in the DEM +(3+ detectors flipping together). MWPM decoders cannot handle these. + +**Solution**: Proved by Serra-Peralta et al. and Cain et al. (2025): the +per-observable subgraph of a transversal-gate DEM is always graphlike. OSD +exploits this by: + +1. Classifying each detector by (logical_qubit, stabilizer_type) using spatial coordinates +2. For each observable, finding its observing region via boundary edges +3. Extracting a sub-DEM restricted to those detectors (guaranteed graphlike) +4. Running any MWPM decoder on each subgraph independently +5. Combining per-observable corrections via XOR + +```python +from pecos_rslib.qec import ObservableSubgraphDecoder + +# Build OSD with PyMatching as inner decoder +osd = ObservableSubgraphDecoder(dem_string, stab_coords, inner_decoder="pymatching") + +# Decode a syndrome +obs_correction = osd.decode(syndrome) +``` + +### Spatial Coordinates + +OSD requires detector spatial coordinates to classify detectors. These +are typically embedded in the DEM as `detector(x, y, t) D_i` annotations. +The `stab_coords` parameter maps each stabilizer to its (x, y) position +and type (X or Z). + +## Layer 3: Logical Algorithm Decoder + +Adds Pauli frame propagation at transversal gate boundaries: + +| Gate | X frame | Z frame | +|------|---------|---------| +| Hadamard | X <-> Z | Z <-> X | +| CNOT | ctrl X -> target X | target Z -> ctrl Z | +| S gate | X -> X*Z | Z unchanged | +| T injection | Decision point | ancilla Z -> data Z | + +T-gate injection is the only point requiring a real-time decode decision. +All other gates just propagate the frame algebraically. + +```python +from pecos_rslib.qec import LogicalAlgorithmDecoder + +# Build from algorithm descriptor +decoder = LogicalAlgorithmDecoder(descriptor, inner_decoder="pymatching") +correction = decoder.decode(full_syndrome) +``` + +## Layer 4: Budget-Aware Decoding + +Different hardware platforms have different timing constraints: + +| Platform | Reaction time | Strategy | +|----------|--------------|----------| +| Superconducting | ~1 us | Minimal windows, no overlap | +| Neutral atom | ~1 ms | d-round windows, d/2 overlap | +| Ion trap | ~10 ms | Large windows, full overlap | +| Offline | unlimited | Full-circuit decode | + +The `DecodeBudget` automatically selects window size and overlap: + +```python +from pecos_rslib.qec import LogicalCircuitDecoder + +# Budget-aware: automatically selects strategy +decoder = LogicalCircuitDecoder( + descriptor, + budget="neutral_atom", # or "superconducting", "unlimited" + inner_decoder="pymatching", +) +``` + +## Windowed Decoding + +For deep circuits, the observing region can span too many rounds, degrading +accuracy. Windowed decoding splits the time axis: + +- **Non-overlapping**: each detector in exactly one window (fastest) +- **Overlapping**: buffer zones extend beyond core for matching context (more accurate) +- **Streaming**: commit previous windows and slide forward (real-time) + +The `WindowedOsdDecoder` implements windowed OSD: + +```python +from pecos_rslib.qec import WindowedOsdDecoder + +decoder = WindowedOsdDecoder( + dem_string, stab_coords, + inner_decoder="pymatching", + step=8, # core window size in time steps + buffer=4, # buffer on each side +) +``` + +## Streaming Decode + +For real-time operation, the `StreamingDecoder` trait accepts syndrome +data round-by-round: + +```rust +// Rust API +trait StreamingDecoder { + fn feed_round(&mut self, round: usize, detectors: &[(u32, u8)]) -> Result; + fn flush(&mut self) -> Result; + fn accumulated_obs(&self) -> u64; +} +``` + +The `CommittedOsd` implements streaming with software commitment (Cain et al.): +committed detectors are masked in future decodes, preventing past decisions +from being revisited. + +## DEM Generation for Decoders + +The choice of DEM generation method affects decoder accuracy: + +| Method | Coherent noise | PyMatching LER | Tesseract LER | +|--------|---------------|----------------|---------------| +| `from_circuit` (stochastic only) | ignores | baseline | baseline | +| `coherent_dem_decomposed` (EEG) | handles | 17% better | 10% better | +| `noise_characterization` (EEG) | handles | 17% better | 10% better | + +For circuits with coherent noise (idle Z-rotations), use `coherent_dem_decomposed` +or `noise_characterization` which produce properly decomposed DEMs with +Heisenberg-exact probabilities. + +## Summary + +The decoder architecture separates concerns cleanly: + +- **Inner decoders** solve the matching/search problem on graphlike DEMs +- **OSD** handles transversal gate hyperedges via proven subgraph decomposition +- **Frame propagation** tracks corrections through gate boundaries algebraically +- **Budgets** adapt decode strategy to hardware constraints automatically +- **Streaming** enables real-time operation via round-by-round feeding diff --git a/docs/development/DEVELOPMENT.md b/docs/development/DEVELOPMENT.md index a64cb0750..8ecee016e 100644 --- a/docs/development/DEVELOPMENT.md +++ b/docs/development/DEVELOPMENT.md @@ -28,15 +28,14 @@ For developers who want to contribute or modify PECOS: 1. Make sure you have [Python](https://www.python.org/downloads/) and [Rust](https://www.rust-lang.org/tools/install) installed for your system. -2. Install all dev tools with a single command: +2. Install the pre-clone dev tools from crates.io: ```sh - cargo install --locked uv just pecos + cargo install --locked uv just ``` This installs: - `uv` - Python package manager - `just` - Command runner for build tasks - - `pecos` - PECOS dev tools (llvm, cuda, rust, python commands) 3. Clone the repository: ```sh @@ -44,12 +43,31 @@ For developers who want to contribute or modify PECOS: cd PECOS ``` -4. Create the development environment: +4. Install the PECOS developer CLI from the repo: + ```sh + cargo install --path crates/pecos-cli + ``` + + This installs the `pecos` binary (llvm, cuda, cuquantum, rust, python, deps commands). + +5. Create the development environment: ```sh uv sync ``` -5. **LLVM 14 Setup (Required for LLVM IR/QIS Support)** + `uv sync` installs the default `dev` and `test` groups (lint, build, + docs, and pytest tooling). Optional groups you may want to add: + + | Group | When to enable | Command | + |---------------|-------------------------------------------------------------|-------------------------------| + | `examples` | Running notebooks under `examples/` or DataFrame benchmarks | `uv sync --group examples` | + | `numpy-compat`| Verifying older NumPy/SciPy minimums | `uv sync --group numpy-compat`| + | `cuda` | Building/running GPU simulators (requires CUDA toolkit) | `uv sync --group cuda` | + + Combine groups with multiple `--group` flags + (e.g. `uv sync --group examples --group cuda`). + +6. **LLVM 14 Setup (Required for LLVM IR/QIS Support)** PECOS requires LLVM version 14 for LLVM IR execution features. @@ -61,7 +79,7 @@ For developers who want to contribute or modify PECOS: For detailed installation instructions for all platforms (macOS, Linux, Windows), see the [**LLVM Setup Guide**](../user-guide/llvm-setup.md). -6. You may wish to explicitly activate the environment for development. To do so: +7. You may wish to explicitly activate the environment for development. To do so: === "Linux/Mac" ```sh @@ -73,24 +91,24 @@ For developers who want to contribute or modify PECOS: .\.venv\Scripts\activate ``` -6. Build the project in editable mode +8. Build the project in editable mode ```sh just build ``` Other build options: `just build-release` (optimized), `just build-native` (optimized for your CPU). -7. Run all Python and Rust tests: +9. Run all Python and Rust tests: ```sh just test ``` Note: Make sure you have run a build command before running tests. -8. Run linters using pre-commit (after [installing it](https://pre-commit.com/)) to make sure all everything is properly linted/formated - ```sh - just lint - ``` +10. Run linters using pre-commit (after [installing it](https://pre-commit.com/)) to make sure all everything is properly linted/formated + ```sh + just lint + ``` -9. To deactivate your development venv: +11. To deactivate your development venv: ```sh deactivate ``` @@ -127,7 +145,7 @@ PECOS uses `~/.pecos/` to store external dependencies and build artifacts that c ``` ~/.pecos/ ├── llvm/ # LLVM-14 installation (for QIR/LLVM IR execution) -├── deps/ # Downloaded C++ dependencies (Stim, QuEST, Qulacs, etc.) +├── deps/ # Downloaded C++ dependencies (Stim, etc.) └── cache/ # Build artifacts and intermediate files ``` diff --git a/docs/development/ast-infrastructure.md b/docs/development/ast-infrastructure.md index 97c04d192..67496cb84 100644 --- a/docs/development/ast-infrastructure.md +++ b/docs/development/ast-infrastructure.md @@ -25,6 +25,8 @@ Converts compiled Guppy programs (HUGR format) to SLR-AST for analysis and code **Key functions:** ```python +from guppylang import guppy +from guppylang.std.quantum import h, measure, qubit from pecos.circuit_converters.hugr_to_ast import guppy_to_ast, hugr_to_ast @@ -145,9 +147,21 @@ print(qasm) ### Serialization Round-trip ```python +from guppylang import guppy +from guppylang.std.quantum import h, measure, qubit +from pecos.circuit_converters.hugr_to_ast import guppy_to_ast from pecos.slr.ast.serialize import ast_to_json, json_to_ast from pecos.slr.ast.compare import ast_equal + +@guppy +def my_circuit() -> bool: + q = qubit() + h(q) + return measure(q) + + +ast = guppy_to_ast(my_circuit) json_str = ast_to_json(ast) restored = json_to_ast(json_str) assert ast_equal(ast, restored) diff --git a/docs/development/foreign-plugins.md b/docs/development/foreign-plugins.md index dccab9882..c0dcf2783 100644 --- a/docs/development/foreign-plugins.md +++ b/docs/development/foreign-plugins.md @@ -98,6 +98,7 @@ class MyDecoder: # Wrap and use decoder = pecos_rslib.PyForeignDecoder(MyDecoder(100, 50)) +syndrome_bytes = bytes(100) result = decoder.decode(syndrome_bytes) ``` @@ -276,7 +277,7 @@ Foreign code can create and run PECOS quantum engines via the C ABI: | State vector | `"state_vec"` | Full state vector simulation | | Sparse stabilizer | `"sparse_stab"` | Clifford-only, sparse tableau | | Stabilizer | `"stabilizer"` | Clifford-only, standard tableau | -| Clifford+RZ | `"clifford_rz"` | Sum-over-Cliffords for T/RZ gates | +| StabVec | `"stab_vec"` | Sum-over-Cliffords for T/RZ gates | | Density matrix | `"density_matrix"` | Mixed state simulation | | Coin toss | `"coin_toss"` | Random outcomes (testing) | diff --git a/docs/user-guide/circuit-representation.md b/docs/user-guide/circuit-representation.md index 6a69fcdd9..a450cca23 100644 --- a/docs/user-guide/circuit-representation.md +++ b/docs/user-guide/circuit-representation.md @@ -245,8 +245,9 @@ Gates can have arbitrary metadata attached: # Multiple metadata entries circuit.cx([(0, 1)]).meta("duration_ns", 50) - # Measurements break the chain but still support metadata - circuit.mz([0]).meta("basis", "Z") + # Measurements return refs (not the circuit), so chain separately + circuit.mz([0]) + circuit.meta("basis", "Z") ``` === ":fontawesome-brands-rust: Rust" @@ -261,8 +262,9 @@ Gates can have arbitrary metadata attached: // Multiple metadata entries circuit.cx(&[(0, 1)]).meta("duration_ns", Attribute::Int(50)); - // Measurements break the chain but still support metadata - circuit.mz(&[0]).meta("basis", Attribute::String("Z".into())); + // Measurements return refs (not &mut Self), so chain separately + circuit.mz(&[0]); + circuit.meta("basis", Attribute::String("Z".into())); ``` ### Circuit Analysis @@ -272,7 +274,10 @@ Gates can have arbitrary metadata attached: from pecos.quantum import DagCircuit circuit = DagCircuit() - circuit.h([0]).cx([(0, 1)]).h([1]).cx([(1, 2)]).mz([0]).mz([1]).mz([2]) + circuit.h([0]).cx([(0, 1)]).h([1]).cx([(1, 2)]) + circuit.mz([0]) + circuit.mz([1]) + circuit.mz([2]) # Basic metrics print(f"Total gates: {circuit.gate_count()}") diff --git a/docs/user-guide/cli.md b/docs/user-guide/cli.md index 763badcd6..660b064ce 100644 --- a/docs/user-guide/cli.md +++ b/docs/user-guide/cli.md @@ -108,8 +108,6 @@ Compiled Features: [x] selene - Selene QIS runtime [x] wasm - WebAssembly foreign objects [ ] llvm - LLVM/QIS compilation - [ ] quest - QuEST simulator backend - [ ] qulacs - Qulacs simulator backend Simulators: statevector - Full quantum state simulation (default) diff --git a/docs/user-guide/cuda-setup.md b/docs/user-guide/cuda-setup.md index ff242169b..c8f90ddcd 100644 --- a/docs/user-guide/cuda-setup.md +++ b/docs/user-guide/cuda-setup.md @@ -319,7 +319,6 @@ pip install quantum-pecos | Simulator | Hardware | Qubits | Gates | Speed | Installation | |-----------|----------|--------|-------|-------|--------------| | StateVec (CPU) | Any | ~25 | All | Baseline | Easy | -| Qulacs (CPU) | Any | ~28 | All | 2-3x faster | Easy | | CuStateVec (Python) | NVIDIA GPU | ~30 | All | 10-50x faster | Medium | | CudaStateVec (Rust) | NVIDIA GPU | ~30 | All | 10-50x faster | Complex | | CudaStabilizer (Rust) | NVIDIA GPU | 1000s | Clifford only | Very fast | Complex | @@ -354,18 +353,6 @@ The Rust bindings provide direct cuQuantum integration without Python package de - Integration with quantum-pecos's HybridEngine - Reproducible simulations with seed support -### Rust GPU Simulators (QuEST) - -**Status**: Limited Support (CPU-only with CUDA 13) - -- **Engine**: QuEST (Quantum Exact Simulation Toolkit) -- **CUDA Version**: Requires CUDA 11 or 12 (incompatible with CUDA 13) -- **Issue**: QuEST uses deprecated `thrust::unary_function` and `thrust::binary_function` classes that were removed in modern CUDA/Thrust versions -- **Workaround**: Automatically falls back to CPU-only QuEST build -- **Impact**: Minimal - use CudaStateVec or Python CuStateVec instead - -The Rust QuEST simulator is currently incompatible with CUDA 13 due to deprecated thrust classes. - ## Rust cuQuantum Bindings Setup To use the Rust-based CUDA simulators (CudaStateVec, CudaStabilizer), you need: @@ -377,6 +364,16 @@ To use the Rust-based CUDA simulators (CudaStateVec, CudaStabilizer), you need: ### Installing cuQuantum SDK +**Recommended:** use the `pecos` CLI to download and install into `~/.pecos/deps/cuquantum/`: + +```bash +pecos install cuquantum +``` + +This mirrors the LLVM setup flow and is the same pattern used by `pecos install llvm` / `pecos install cuda`. The PECOS build system then picks up the install automatically — no environment variables to set. + +**Manual install (if you already have cuQuantum or need a specific version):** + 1. Download from [NVIDIA cuQuantum](https://developer.nvidia.com/cuquantum-sdk) 2. Extract to a known location (e.g., `/opt/nvidia/cuquantum`) 3. Set environment variables: @@ -402,34 +399,37 @@ from pecos_rslib_cuda import is_cuquantum_available print(f"cuQuantum available: {is_cuquantum_available()}") -# State vector simulator (up to ~30 qubits) -from pecos.simulators import CudaStateVec +if is_cuquantum_available(): + # State vector simulator (up to ~30 qubits) + from pecos.simulators import CudaStateVec -sim = CudaStateVec(10) -sim.run_gate("H", [0]) -sim.run_gate("CX", [(0, 1)]) -results = sim.run_gate("Measure", [0, 1]) + sim = CudaStateVec(10) + sim.run_gate("H", [0]) + sim.run_gate("CX", [(0, 1)]) + results = sim.run_gate("Measure", [0, 1]) -# Stabilizer simulator (Clifford-only, scales to 1000s of qubits) -from pecos.simulators import CudaStabilizer + # Stabilizer simulator (Clifford-only, scales to 1000s of qubits) + from pecos.simulators import CudaStabilizer -sim = CudaStabilizer(1000) -sim.run_gate("H", [0]) -for i in range(100): - sim.run_gate("CX", [(i, i + 1)]) -results = sim.run_gate("Measure", list(range(100))) + sim = CudaStabilizer(1000) + sim.run_gate("H", [0]) + for i in range(100): + sim.run_gate("CX", [(i, i + 1)]) + results = sim.run_gate("Measure", list(range(100))) -# Using with QuantumSimulator -from pecos.simulators.quantum_simulator import QuantumSimulator + # Using with QuantumSimulator + from pecos.simulators.quantum_simulator import QuantumSimulator -qsim = QuantumSimulator(backend="CudaStateVec") -qsim.init(4) + qsim = QuantumSimulator(backend="CudaStateVec") + qsim.init(4) -# Direct access to cuQuantum components -from pecos_rslib_cuda import CuTensorNet, CuDensityMat + # Direct access to cuQuantum components + from pecos_rslib_cuda import CuTensorNet, CuDensityMat -print(f"cuTensorNet version: {CuTensorNet.version()}") -print(f"cuDensityMat version: {CuDensityMat.version()}") + print(f"cuTensorNet version: {CuTensorNet.version()}") + print(f"cuDensityMat version: {CuDensityMat.version()}") +else: + print("Rust cuQuantum bindings are not available on this machine.") ``` ### Choosing Between Python and Rust Bindings @@ -493,10 +493,13 @@ To use GPU simulators in PECOS: print(f"cuQuantum available: {is_cuquantum_available()}") - from pecos.simulators import CudaStateVec, CudaStabilizer + if is_cuquantum_available(): + from pecos.simulators import CudaStateVec, CudaStabilizer - sim = CudaStateVec(4) # State vector (~30 qubits max) - sim = CudaStabilizer(1000) # Stabilizer (1000s of qubits, Clifford only) + sim = CudaStateVec(4) # State vector (~30 qubits max) + sim = CudaStabilizer(1000) # Stabilizer (1000s of qubits, Clifford only) + else: + print("Rust cuQuantum bindings are not available on this machine.") ``` ### Choosing an Approach @@ -505,5 +508,3 @@ To use GPU simulators in PECOS: - **For stabilizer simulations**: Use CudaStabilizer (Rust) for 1000s of qubits - **For reproducibility**: Rust bindings have full seed support - **For density matrices**: Use CuDensityMat (Rust) for open quantum systems - -**Note**: If you see warnings about QuEST GPU compilation failing, this is expected with CUDA 13 and does not affect the cuQuantum-based simulators. diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md new file mode 100644 index 000000000..40ab77e81 --- /dev/null +++ b/docs/user-guide/fault-catalog.md @@ -0,0 +1,388 @@ +# Fault Catalog Tutorial + +The fault catalog API exposes the physical fault mechanisms in a `TickCircuit`. +It is useful when you want to inspect fault locations, build lookup tables, +debug detector/observable metadata, or lazily enumerate low-weight fault +configurations. + +The core model is: + +- each `FaultLocation` is an independent physical fault mechanism +- each location has one or more `FaultAlternative`s +- exactly one alternative is chosen when the location fires +- detector, measurement, and observable effects combine by XOR parity + +## Inputs + +A fault catalog needs two inputs: + +1. a `TickCircuit` +2. stochastic noise parameters + +The circuit must already have detector and observable metadata: + +- `num_measurements` +- `detectors` +- `observables` + +The catalog does not infer detector definitions from the gate sequence. It uses +the metadata on the circuit to map raw measurement flips into detector and +observable flips. + +## Python: Build a Small Catalog + +```python +from pecos.quantum import PauliString, TickCircuit +from pecos_rslib_exp import depolarizing, fault_catalog + +circuit = TickCircuit() +circuit.tick().h([0]) +circuit.tick().mz([0]) + +circuit.set_meta("num_measurements", "1") +circuit.set_meta("detectors", '[{"records":[-1]}]') +circuit.set_meta("observables", '[{"records":[-1]}]') + +noise = depolarizing().p1(0.03).p2(0.0).p_meas(0.01).p_prep(0.0) +catalog = fault_catalog(circuit, noise) +``` + +The returned object is sequence-like: + +```python +print(len(catalog)) +print(catalog[0]) +print(catalog[-1]) + +for location in catalog: + print(location.tick, location.gate_type, location.channel) +``` + +It also exposes the underlying locations list: + +```python +locations = catalog.locations +``` + +## Location Fields + +Each `FaultLocation` represents one physical mechanism with nonzero channel +probability. + +| Field | Meaning | +|---|---| +| `tick` | Tick index in the `TickCircuit` | +| `gate_index` | Gate index within the tick | +| `gate_type` | Gate name, such as `"H"`, `"CX"`, or `"MZ"` | +| `qubits` | Qubits acted on by this gate | +| `channel` | `"p1"`, `"p2"`, `"p_meas"`, or `"p_prep"` | +| `channel_probability` | Total probability that the mechanism fires, `p_i` | +| `no_fault_probability` | Probability the mechanism does not fire, `1 - p_i` | +| `num_alternatives` | Number of alternatives at this location, `k_i` | +| `faults` | List of `FaultAlternative` objects | + +Example: + +```python +for loc in catalog: + print( + loc.tick, + loc.gate_type, + loc.channel, + loc.channel_probability, + loc.no_fault_probability, + loc.num_alternatives, + ) +``` + +The catalog includes locations with nonzero channel probability even when all +alternatives have empty detector/observable effects. This is necessary for +correct probability accounting. + +## Alternative Fields + +Each `FaultAlternative` is one possible outcome when its parent location fires. + +| Field | Meaning | +|---|---| +| `kind` | `"pauli"`, `"measurement_flip"`, or `"prep_flip"` | +| `pauli` | A real PECOS `PauliString` for Pauli faults, or `None` | +| `measurements` | Raw measurement indices flipped by the alternative | +| `detectors` | Detector indices flipped by the alternative | +| `observables` | Observable indices flipped by the alternative | +| `conditional_probability` | `1 / k_i` | +| `absolute_probability` | Marginal alternative probability at the location, `p_i / k_i` | +| `channel_probability` | Same `p_i` as the parent location | + +Example: + +```python +for loc in catalog: + for fault in loc.faults: + if fault.kind == "pauli": + assert isinstance(fault.pauli, PauliString) + else: + assert fault.pauli is None + + print(fault.kind, fault.detectors, fault.observables) +``` + +`fault.absolute_probability` is intentionally local to one fault location. It is +not the probability of "this alternative and no other faults in the circuit." + +## Probability Semantics + +For location `i`: + +```text +p_i = location.channel_probability +k_i = location.num_alternatives +P(no fault at i) = 1 - p_i +P(specific alternative at i) = p_i / k_i +``` + +For a full-circuit configuration: + +```text +configuration_probability + = product selected alternatives (p_i / k_i) + * product unselected locations (1 - p_i) +``` + +For a single selected alternative at location `i`, the full event probability is: + +```python +event_probability = fault.absolute_probability + +for j, loc in enumerate(catalog.locations): + if j != selected_location_index: + event_probability *= loc.no_fault_probability +``` + +## Lazy k-Fault Configurations + +Use `catalog.fault_configurations(k)` to lazily iterate every configuration +where exactly `k` distinct locations fire and one alternative is chosen from +each selected location. + +For `k = 0`, the iterator yields exactly one no-fault configuration: + +```python +configs = list(catalog.fault_configurations(0)) +assert len(configs) == 1 + +no_fault = configs[0] +assert no_fault.location_indices == [] +assert no_fault.alternative_indices == [] +assert no_fault.measurements == [] +assert no_fault.detectors == [] +assert no_fault.observables == [] +assert no_fault.selected_probability == 1.0 +``` + +The no-fault configuration probability is the product of every location's +`no_fault_probability`: + +```python +expected = 1.0 +for loc in catalog.locations: + expected *= loc.no_fault_probability + +assert abs(no_fault.configuration_probability - expected) < 1e-12 +``` + +For `k > 0`, each yielded `FaultConfiguration` has: + +| Field | Meaning | +|---|---| +| `location_indices` | Indices into `catalog.locations` | +| `alternative_indices` | Chosen alternative index for each selected location | +| `locations` | The selected `FaultLocation` objects | +| `faults` | The selected `FaultAlternative` objects | +| `measurements` | XOR-combined measurement effects | +| `detectors` | XOR-combined detector effects | +| `observables` | XOR-combined observable effects | +| `selected_probability` | Product of selected `absolute_probability` values | +| `configuration_probability` | Selected probability times no-fault probabilities for unselected locations | + +The iterator is lazy: + +```python +it = catalog.fault_configurations(1) +first = next(it) + +print(first.location_indices) +print(first.alternative_indices) +print(first.locations[0] is catalog.locations[first.location_indices[0]]) +print(first.faults[0] is first.locations[0].faults[first.alternative_indices[0]]) +``` + +## XOR Parity + +When multiple alternatives are selected, effects combine by XOR parity. If two +faults flip the same detector, that detector cancels from the combined +configuration. + +```python +for event in catalog.fault_configurations(2): + print(event.detectors, event.observables, event.configuration_probability) +``` + +This is the right behavior for detector syndromes and logical observable flips. +It is also why low-weight decoder tests should apply the selected correction and +check the residual logical by XOR. + +## Building a Small Lookup Table + +A lookup decoder table groups configuration probability by: + +```text +detector syndrome -> logical observable class -> probability +``` + +For a truncated table: + +```python +from collections import defaultdict + +def add_weight(table, syndrome, logical, probability): + table[tuple(syndrome)][tuple(logical)] += probability + +table = defaultdict(lambda: defaultdict(float)) + +for k in range(0, 3): + for event in catalog.fault_configurations(k): + add_weight( + table, + event.detectors, + event.observables, + event.configuration_probability, + ) + +decoder = {} +for syndrome, logical_weights in table.items(): + best_logical = max(logical_weights.items(), key=lambda item: item[1])[0] + decoder[syndrome] = best_logical +``` + +To apply the decoder to an enumerated event, XOR the event's logical class with +the selected correction: + +```python +def xor_sorted(a, b): + out = set(a) + for item in b: + if item in out: + out.remove(item) + else: + out.add(item) + return tuple(sorted(out)) + +for event in catalog.fault_configurations(1): + correction = decoder[tuple(event.detectors)] + residual = xor_sorted(event.observables, correction) + print(event.detectors, residual) +``` + +## Rust API + +The Rust API lives in `pecos-qec`: + +```rust +use pecos_qec::fault_tolerance::fault_sampler::{ + build_fault_catalog, StochasticNoiseParams, +}; +use pecos_quantum::{Attribute, TickCircuit}; + +let mut circuit = TickCircuit::new(); +circuit.tick().h(&[0]); +circuit.tick().mz(&[0]); + +circuit.set_meta("num_measurements", Attribute::String("1".into())); +circuit.set_meta( + "detectors", + Attribute::String(r#"[{"records":[-1]}]"#.into()), +); +circuit.set_meta( + "observables", + Attribute::String(r#"[{"records":[-1]}]"#.into()), +); + +let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, +}; + +let catalog = build_fault_catalog(&circuit, &noise).unwrap(); +``` + +Iterate locations and alternatives: + +```rust +for loc in &catalog.locations { + println!( + "tick={} gate={:?} channel={:?} p={} k={}", + loc.tick, + loc.gate_type, + loc.channel, + loc.channel_probability, + loc.num_alternatives + ); + + for fault in &loc.faults { + println!( + " {:?} dets={:?} obs={:?} p_alt={}", + fault.kind, + fault.affected_detectors, + fault.affected_observables, + fault.absolute_probability + ); + } +} +``` + +Iterate configurations: + +```rust +for event in catalog.fault_configurations(2) { + println!( + "locations={:?} alternatives={:?} dets={:?} obs={:?} p={}", + event.location_indices, + event.alternative_indices, + event.affected_detectors, + event.affected_observables, + event.configuration_probability + ); +} +``` + +The Rust iterator borrows the catalog and does not materialize all +configurations up front. + +## Common Pitfalls + +- `fault.absolute_probability` is `p_i / k_i`, not a full-circuit event + probability. +- Empty-effect locations are real physical mechanisms and must remain in the + catalog for normalization. +- `catalog.fault_configurations(k)` means exactly `k` distinct physical + locations fire, not at most `k`. +- Detector and observable metadata must be correct before building the catalog. + Missing boundary detectors can make a correct decoder appear to fail. +- The current catalog models the supported stochastic channels in + `StochasticNoiseParams`: `p1`, `p2`, `p_meas`, and `p_prep`. + +## Larger Example + +The Rust example `examples/surface/d3_fault_catalog_lookup.rs` builds a +distance-3 surface-code memory experiment, walks `fault_configurations(k)` for +`k = 0..=2`, and aggregates a truncated lookup decoder table. + +Run it from the repository root: + +```bash +cargo run -p pecos-qec --example surface_d3_fault_catalog_lookup +``` + diff --git a/docs/user-guide/gates.md b/docs/user-guide/gates.md index dc8e6937c..57896dbfa 100644 --- a/docs/user-guide/gates.md +++ b/docs/user-guide/gates.md @@ -1073,7 +1073,6 @@ These operations measure and then prepare the qubit in a specific eigenstate reg |-----------|---------------|-------------------|-------| | **SparseStab** | All | None | Default, fastest for QEC | | **StateVec** | All | All | Pure Rust state vector | -| **Qulacs** | All | All | High-performance C++ backend | | **CuStateVec** | All | All | GPU-accelerated (requires CUDA) | | **MPS** | All | All | Tensor network (requires CUDA) | | **PauliProp** | All | None | Error propagation tracking | diff --git a/docs/user-guide/getting-started.md b/docs/user-guide/getting-started.md index 3c75832ad..0997eebe3 100644 --- a/docs/user-guide/getting-started.md +++ b/docs/user-guide/getting-started.md @@ -180,7 +180,6 @@ Most users won't need these, but they're available for specialized use cases: |---------|-----------------|-------------| | **LLVM** (Rust only) | QIR/LLVM IR execution | [LLVM Setup](llvm-setup.md) | | **CUDA** | GPU-accelerated simulation | [CUDA Setup](cuda-setup.md) | -| **QuEST** | Alternative simulator backend | `pip install quantum-pecos[all]` | !!! tip "Python users" Pre-built wheels include LLVM support—no extra setup needed. diff --git a/docs/user-guide/llvm-setup.md b/docs/user-guide/llvm-setup.md index c5fa07ffd..3a523ea88 100644 --- a/docs/user-guide/llvm-setup.md +++ b/docs/user-guide/llvm-setup.md @@ -23,7 +23,7 @@ If you don't need QIS LLVM IR/QIR execution features, you can skip LLVM installa ### Option 1: Automatic Installation (Recommended) -Use the `pecos-llvm` CLI tool to automatically download and install LLVM 14.0.6: +Use the `pecos` CLI (`pecos install llvm`, or `cargo run -p pecos-cli -- install llvm` in a source checkout) to automatically download and install LLVM 14.0.6: ```bash # Install LLVM 14.0.6 to ~/.pecos/deps/llvm-14/ (~400MB, ~5 minutes) @@ -110,9 +110,9 @@ cargo run -p pecos-cli -- llvm version cargo run -p pecos-cli -- llvm find ``` -## pecos-llvm CLI Reference +## `pecos llvm` CLI Reference -The `pecos llvm` CLI tool provides several useful commands: +The `pecos llvm` subcommand provides several useful commands: ### `install` @@ -214,7 +214,7 @@ LLVM_SYS_140_PREFIX = { value = "/path/to/llvm", force = true } ### Detection Priority -The `pecos-llvm` tool searches for LLVM 14 in this order: +The `pecos llvm` tooling searches for LLVM 14 in this order: 1. **Home directory:** - Windows: `~/.pecos/deps/llvm-14` @@ -244,7 +244,7 @@ The `pecos-llvm` tool searches for LLVM 14 in this order: - Uses `.7z` archives for distribution - Pure Rust extraction (no external tools required) -- Official LLVM Windows installer lacks development files - use `pecos-llvm install` or community packages +- Official LLVM Windows installer lacks development files - use `pecos install llvm` or community packages ### Security diff --git a/docs/user-guide/qec-guppy.md b/docs/user-guide/qec-guppy.md index 078f35d25..5318a6afc 100644 --- a/docs/user-guide/qec-guppy.md +++ b/docs/user-guide/qec-guppy.md @@ -205,6 +205,62 @@ prog = make_color_transversal_cnot_d3(num_rounds=1) prog = make_surface_transversal_cnot(distance=5, num_rounds=2) ``` +## Writing Your Own QEC Circuit + +You can write QEC circuits directly in Guppy without using the factory functions. Here is a minimal 3-qubit repetition code: + +```python +from guppylang import guppy +from guppylang.std.builtins import array +from guppylang.std.quantum import qubit, cx, measure, measure_array + + +@guppy.struct +class RepSyndrome: + """Two-bit syndrome for the 3-qubit repetition code.""" + + s: array[bool, 2] + + +@guppy +def extract_rep_syndrome(data: array[qubit, 3]) -> RepSyndrome: + """Measure Z_0 Z_1 and Z_1 Z_2 stabilizers.""" + a0 = qubit() + a1 = qubit() + + # Z_0 Z_1 stabilizer + cx(data[0], a0) + cx(data[1], a0) + + # Z_1 Z_2 stabilizer + cx(data[1], a1) + cx(data[2], a1) + + s0 = measure(a0) + s1 = measure(a1) + + return RepSyndrome(array(s0, s1)) + + +@guppy +def rep_code_experiment() -> tuple[array[bool, 3], RepSyndrome]: + """Run one round of the 3-qubit repetition code.""" + data = array(qubit(), qubit(), qubit()) + syndrome = extract_rep_syndrome(data) + results = measure_array(data) + return results, syndrome + + +# Verify it compiles +compiled = rep_code_experiment.compile() +``` + +Key patterns: +- `@guppy.struct` defines data types (qubits are linear — they must be consumed) +- `@guppy` functions can call each other freely +- Ancilla qubits are allocated with `qubit()` and consumed by `measure()` +- Use `measure_array()` to measure all qubits in an array at once + ## Generated Code Structure ```hidden-python @@ -256,28 +312,20 @@ def measure_z_stab_0(az: qubit, data: array[qubit, 9]) -> bool: ### Syndrome Extraction - +The generated module includes a `syndrome_extraction` function that applies all stabilizer measurements in a parallelized CNOT schedule and returns the syndrome: + ```python -@guppy -def syndrome_extraction( - surf: SurfaceCode_3x3, - ax: qubit, - az: qubit, -) -> Syndrome_3x3: - """Extract full syndrome.""" - # Z stabilizers - sz0 = measure_z_stab_0(az, surf.data) - sz1 = measure_z_stab_1(az, surf.data) - # ... - - # X stabilizers - sx0 = measure_x_stab_0(ax, surf.data) - sx1 = measure_x_stab_1(ax, surf.data) - # ... - - return Syndrome_3x3(array(sx0, sx1, ...), array(sz0, sz1, ...)) +from pecos.guppy import generate_surface_code_module + +source = generate_surface_code_module(d=3) + +# The generated module contains the full syndrome extraction circuit +assert "def syndrome_extraction" in source +assert "Syndrome_3x3" in source ``` +To see the full generated code, see [Viewing Generated Source](#viewing-generated-source) below. + ## Viewing Generated Source To see the generated Guppy source code: diff --git a/docs/user-guide/simulators.md b/docs/user-guide/simulators.md index bf4901496..397a497d7 100644 --- a/docs/user-guide/simulators.md +++ b/docs/user-guide/simulators.md @@ -78,13 +78,17 @@ fn main() -> Result<(), Box> { | Simulator | Type | Best For | Requirements | |-----------|------|----------|--------------| | **SparseStab** | Stabilizer | QEC simulations, Clifford circuits | None (default) | +| **Stabilizer** | Stabilizer | Dense Clifford circuits | None | | **StateVec** | State vector | Arbitrary circuits, small systems | None | -| **Qulacs** | State vector | High-performance state vector | None | +| **StabVec** | Clifford + Rz | Clifford circuits with Z rotations | None | | **PauliProp** | Fault tracking | Error propagation analysis | None | -| **CuStateVec** | State vector (GPU) | Large circuits with GPU | CUDA, cuQuantum | +| **CuStateVec** | State vector (GPU, Python) | Large circuits with GPU | CUDA, cuQuantum | +| **CudaStateVec** | State vector (GPU, Rust) | Large circuits, reproducible seeded runs | CUDA, cuQuantum, cuda-rust build | +| **CudaStabilizer** | Stabilizer (GPU, Rust) | Very large Clifford circuits (1000s of qubits) | CUDA, cuQuantum, cuda-rust build | | **MPS** | Tensor network | Low-entanglement circuits | CUDA, cuQuantum | -| **QuestStateVec** | State vector | Full state simulation | None | -| **QuestDensityMatrix** | Density matrix | Noisy/mixed state simulation | None | +| **density_matrix** | Density matrix | Noisy/mixed state simulation | None | + +Two additional specialized backends—**SparseStabPy** (pure-Python reference implementation for debugging) and **CoinToss** (random measurement outcomes for testing)—are documented below but rarely used in production. ## Choosing a Simulator @@ -99,33 +103,15 @@ fn main() -> Result<(), Box> { │ │ │ ▼ ▼ ▼ SparseStab ←───┐ ┌─────┴─────┐ PauliProp - (fastest) │ │ │ + Stabilizer │ │ │ │ Small system? GPU available? │ │ │ │ ▼ ▼ │ StateVec CuStateVec - │ Qulacs MPS + │ StabVec MPS │ │ │ ▼ - └── Need mixed states? ──→ QuestDensityMatrix -``` - -## Setup - -The examples below use this Bell state circuit: - -```python -from pecos import sim, Qasm - -circuit = """ -OPENQASM 2.0; -include "qelib1.inc"; -qreg q[2]; -creg c[2]; -h q[0]; -cx q[0], q[1]; -measure q -> c; -""" + └── Need mixed states? ──→ density_matrix ``` ## Stabilizer Simulators @@ -182,6 +168,26 @@ from pecos.simulators import SparseStabPy results = sim(Qasm(circuit)).quantum(SparseStabPy).run(100) ``` +### Stabilizer + +Dense Rust stabilizer backend for Clifford circuits. + +```python +from pecos.simulators import Stabilizer + +results = sim(Qasm(circuit)).quantum(Stabilizer).run(100) +``` + +**Strengths:** + +- Rust backend with a straightforward dense stabilizer representation +- Good compatibility fallback for Clifford-only workloads + +**Limitations:** + +- Only Clifford gates +- Usually not as memory-efficient as `SparseStab` on sparse QEC circuits + ## State Vector Simulators State vector simulators can simulate **any quantum circuit** but scale exponentially (2^n memory for n qubits). Practical for ~25-30 qubits on typical hardware. @@ -211,36 +217,20 @@ Pure Rust state vector implementation. - Supports arbitrary gates (including T, rotation gates) - Good baseline performance -### Qulacs (Python only) +### StabVec -High-performance state vector simulator via the Qulacs C++ library. +Rust backend specialized for Clifford circuits plus Z-axis rotations. ```python -from pecos.simulators import Qulacs +from pecos.simulators import StabVec -results = sim(Qasm(circuit)).quantum(Qulacs).run(100) +results = sim(Qasm(circuit)).quantum(StabVec).run(100) ``` **Strengths:** -- Highly optimized C++ backend -- SIMD acceleration -- Often faster than StateVec for larger circuits - -### QuestStateVec (Python only) - -State vector simulator powered by the QuEST library. - -```python -from pecos.simulators import QuestStateVec - -results = sim(Qasm(circuit)).quantum(QuestStateVec).run(100) -``` - -**Strengths:** - -- Full state vector simulation with high precision -- Thread-safe: each instance operates on independent quantum registers +- Efficient for Clifford-heavy workloads that need `RZ` support +- Uses the native Rust backend that ships with PECOS ## GPU-Accelerated Simulators @@ -250,6 +240,7 @@ For large circuits, GPU acceleration can provide significant speedups. NVIDIA cuQuantum-powered state vector simulator. + ```python from pecos.simulators import CuStateVec @@ -290,12 +281,12 @@ results = sim(Qasm(circuit)).quantum(MPS).run(100) Density matrix simulators represent mixed quantum states, enabling simulation of decoherence and non-unitary operations. -### QuestDensityMatrix (Python only) +### density_matrix ```python -from pecos.simulators import QuestDensityMatrix +from pecos.simulators import density_matrix -results = sim(Qasm(circuit)).quantum(QuestDensityMatrix).run(100) +results = sim(Qasm(circuit)).quantum(density_matrix).run(100) ``` **Use cases:** @@ -386,11 +377,14 @@ Approximate performance characteristics (relative, not absolute): | Simulator | Speed (Clifford) | Speed (Universal) | Memory | Max Qubits | |-----------|------------------|-------------------|--------|------------| | SparseStab | ★★★★★ | N/A | Low | 1000+ | +| Stabilizer | ★★★★ | N/A | Medium | 1000+ | | StateVec | ★★★ | ★★★ | 2^n | ~25-30 | -| Qulacs | ★★★★ | ★★★★ | 2^n | ~25-30 | +| StabVec | ★★★★ | Limited to Clifford + Rz | Low | 1000+ | | CuStateVec | ★★★★ | ★★★★★ | 2^n (GPU) | ~30-35 | +| CudaStateVec | ★★★★ | ★★★★★ | 2^n (GPU) | ~30-35 | +| CudaStabilizer | ★★★★★ | N/A | Low | 1000+ (GPU) | | MPS | ★★★ | ★★★ | ~n × chi² | Varies | -| QuestDensityMatrix | ★★ | ★★ | 4^n | ~15 | +| density_matrix | ★★ | ★★ | 4^n | ~15 | ## Using Simulators with sim() @@ -400,7 +394,7 @@ The `sim()` API lets you switch simulators easily: ```python from pecos import sim, Qasm - from pecos.simulators import SparseStab, StateVec, Qulacs + from pecos.simulators import SparseStab, StateVec, Stabilizer circuit = Qasm( """ @@ -419,7 +413,7 @@ The `sim()` API lets you switch simulators easily: # Explicit simulator selection results = sim(circuit).quantum(StateVec).run(1000) - results = sim(circuit).quantum(Qulacs).run(1000) + results = sim(circuit).quantum(Stabilizer).run(1000) ``` === ":fontawesome-brands-rust: Rust" diff --git a/docs/user-guide/stabilizer-codes.md b/docs/user-guide/stabilizer-codes.md index fff2e13cd..2348222c9 100644 --- a/docs/user-guide/stabilizer-codes.md +++ b/docs/user-guide/stabilizer-codes.md @@ -298,4 +298,4 @@ PECOS separates stabilizer code concerns into layers: - **`StabilizerCode`** (pecos-qec): Mathematical code definition, on-demand analysis. - **`StabilizerCodeSpec`** (pecos-qec): Operational specification with verification and fault tolerance integration. -For architecture details, see [Stabilizer Code Architecture](../development/STABILIZER_CODE_ARCHITECTURE.md). +For architecture details, see `design/STABILIZER_CODE_ARCHITECTURE.md` in the repository root. diff --git a/examples/Dusting off color code code.ipynb b/examples/Dusting off color code code.ipynb index 760e70374..6f6916fed 100644 --- a/examples/Dusting off color code code.ipynb +++ b/examples/Dusting off color code code.ipynb @@ -800,7 +800,7 @@ "metadata": {}, "outputs": [], "source": [ - "from pecos_rslib import DepolarizingNoiseModelBuilder, qasm_engine, sparse_stabilizer\n", + "from pecos_rslib import DepolarizingNoiseModelBuilder, qasm_engine, sparse_stab\n", "from pecos_rslib.programs import QasmProgram" ] }, @@ -842,7 +842,7 @@ " qasm_engine()\n", " .program(QasmProgram.from_string(qasm))\n", " .to_sim()\n", - " .quantum_engine(sparse_stabilizer())\n", + " .quantum_engine(sparse_stab())\n", " .run(5)\n", ")\n", "# Convert to dict and display\n", @@ -899,7 +899,7 @@ "metadata": {}, "outputs": [], "source": [ - "from pecos_rslib import qasm_engine, sparse_stabilizer\n", + "from pecos_rslib import qasm_engine, sparse_stab\n", "from pecos_rslib.programs import QasmProgram" ] }, @@ -916,7 +916,7 @@ " qasm_engine()\n", " .program(QasmProgram.from_string(qasm))\n", " .to_sim()\n", - " .quantum_engine(sparse_stabilizer())\n", + " .quantum_engine(sparse_stab())\n", " .run(5)\n", ")\n", "# Convert to dict and display\n", @@ -1615,7 +1615,7 @@ " qasm_engine()\n", " .program(QasmProgram.from_string(qasm))\n", " .to_sim()\n", - " .quantum_engine(sparse_stabilizer())\n", + " .quantum_engine(sparse_stab())\n", " .run(5)\n", ")\n", "# Convert to dict and display\n", diff --git a/examples/surface/README.md b/examples/surface/README.md new file mode 100644 index 000000000..a0659867f --- /dev/null +++ b/examples/surface/README.md @@ -0,0 +1,182 @@ +# Surface Sweep Examples + +This directory contains the current rotated-surface-code memory sweep tooling: + +- `native_dem_threshold_sweep.py`: runs X/Z memory experiments, fits a per-round + logical error rate, and writes plots plus optional JSON/HTML reports. +- `surface_sweep_report.py`: rebuilds an HTML dashboard from already-generated + sweep artifacts without rerunning simulations. +- `d3_fault_catalog_lookup.rs`: Rust example that builds a distance-3 + surface-code memory experiment, enumerates low-weight fault configurations + with the fault catalog API, and aggregates a truncated lookup decoder table. + +## Rust Fault-Catalog Lookup Example + +Run the d=3 lookup-table example from the PECOS repo root: + +```bash +cargo run -p pecos-qec --example surface_d3_fault_catalog_lookup +``` + +The expensive loop stays in Rust: for `k = 0..=2`, the example lazily walks +`catalog.fault_configurations(k)`, XORs detector/tracked-op effects via the +catalog iterator, and sums `configuration_probability` into a +`syndrome -> logical -> probability` table. + +## Typical Workflow + +Run these commands from the PECOS repo root using your normal project Python +environment. + +```bash +python examples/surface/native_dem_threshold_sweep.py \ + --distances 3 5 7 9 \ + --error-rates 0.004 0.006 0.008 0.01 \ + --bases X Z \ + --shots 1000 \ + --sample-backend native_sampler \ + --save-json --save-html \ + --output-dir /tmp/pecos_surface_highshot_sweep +``` + +This assumes the standard PECOS Python/runtime setup is already available and +that the Selene/native-sampler pieces required by these examples are present. +Use the project's normal setup flow before running these examples if needed. + +Run a full native-sampler sweep with the configuration we have been using: + +Notes: + +- The default duration schedule now uses about four evenly spaced integer round + counts over `r in [2d, 3d]` for each distance. +- If we need to push a bit past `3d`, use `--duration-max-multiplier ...` or + provide an explicit `--duration-multipliers ...` list. +- The fixed-`p` duration plots show fitted duration curves as lines and + observed logical error rates as points with 95% Wilson intervals. + +Open the generated report directly from the sweep run: + +```bash +python examples/surface/native_dem_threshold_sweep.py \ + --distances 3 5 7 9 \ + --error-rates 0.004 0.006 0.008 0.01 \ + --bases X Z \ + --shots 1000 \ + --sample-backend native_sampler \ + --save-json --save-html --open-html \ + --output-dir /tmp/pecos_surface_highshot_sweep +``` + +## Rebuild A Report From Existing Artifacts + +If the SVGs and JSON already exist, rebuild the dashboard without rerunning the +simulations: + +```bash +python examples/surface/surface_sweep_report.py \ + --input-dir /tmp/pecos_surface_highshot_sweep +``` + +To rebuild and open it in the browser: + +```bash +python examples/surface/surface_sweep_report.py \ + --input-dir /tmp/pecos_surface_highshot_sweep \ + --open +``` + +## Re-render Plots From Saved JSON + +The JSON results file is the canonical source of truth -- the plots are +derived. If you want to regenerate plots later (for example to revisit +the data with different formats, or after the SVGs were deleted), pass +`--render-plots`: + +```bash +python examples/surface/surface_sweep_report.py \ + --input-dir /tmp/pecos_surface_highshot_sweep \ + --render-plots --formats svg pdf --open +``` + +This reads `*_results.json`, reconstructs the in-memory data, and rewrites +every plot file before building the dashboard. Use this when you want to +keep only the JSON file long-term (it is small and fully replayable). + +## Merge Multiple Sweep Shards + +Run the same sweep multiple times (same distances, bases, error rates, rounds) +and merge the resulting JSON files for tighter confidence intervals. Each +shard stays on disk -- the merge is read-only. + +```bash +# Run once overnight, seed 12345. +python examples/surface/native_dem_threshold_sweep.py \ + --distances 3 5 7 9 --error-rates 0.004 0.006 0.008 0.01 \ + --bases X Z --shots 5000 --sample-backend native_sampler \ + --seed 12345 --save-json --output-dir /tmp/sweep_mon + +# Run again the next night, same config but fresh seed. +python examples/surface/native_dem_threshold_sweep.py \ + --distances 3 5 7 9 --error-rates 0.004 0.006 0.008 0.01 \ + --bases X Z --shots 5000 --sample-backend native_sampler \ + --seed 99999 --save-json --output-dir /tmp/sweep_tue + +# Merge both shards: shots accumulate per SweepPoint key, fit summaries +# are re-derived from the combined points, and a fresh dashboard + PDF +# report get written to the chosen output directory. +mkdir -p /tmp/sweep_combined +python examples/surface/surface_sweep_report.py \ + --input-dir /tmp/sweep_combined \ + --json-files /tmp/sweep_mon/surface_threshold_sweep_results.json \ + /tmp/sweep_tue/surface_threshold_sweep_results.json \ + --render-plots --report-pdf --open +``` + +Passing multiple `--json-files` always triggers merge mode -- the script +re-renders every plot from the merged data (the existing SVGs in +``--input-dir`` are ignored and overwritten). The merged config in the +dashboard and PDF appendix records the contributing shard paths in +``source_shards`` for provenance. + +## Generate A Single PDF Report + +For archival or sharing, write a single multi-page PDF (cover page with +configuration + timing, then one plot per page): + +```bash +# From a live sweep: +python examples/surface/native_dem_threshold_sweep.py \ + --distances 3 5 7 9 --error-rates 0.004 0.006 0.008 0.01 \ + --bases X Z --shots 5000 --sample-backend native_sampler \ + --save-json --save-report-pdf \ + --output-dir /tmp/sweep_out + +# From existing artifacts (requires *_results.json in input-dir): +python examples/surface/surface_sweep_report.py \ + --input-dir /tmp/sweep_out --report-pdf +``` + +The PDF report is fully rebuildable from the JSON file alone, so you can +archive JSON + PDF and regenerate either from the other. + +## Small Smoke Run + +For a quick sanity check before launching a heavier sweep: + +```bash +python examples/surface/native_dem_threshold_sweep.py \ + --distances 3 5 \ + --error-rates 0.006 \ + --bases X Z \ + --shots 200 \ + --sample-backend native_sampler \ + --save-json --save-html \ + --output-dir /tmp/pecos_surface_fitcurve_check +``` + +This is useful for validating that: + +- Selene/native sampler execution is working +- plots and the HTML dashboard are being generated +- the fixed-`p` duration panels look sensible before spending time on a large + run diff --git a/examples/surface/analyze_data.py b/examples/surface/analyze_data.py new file mode 100644 index 000000000..93dbf66e1 --- /dev/null +++ b/examples/surface/analyze_data.py @@ -0,0 +1,588 @@ +r"""Analyze decoder performance data from JSON shards. + +Reads one or more JSON shards produced by ``generate_data.py`` and +computes: + - Decoder comparison tables (LER + timing at each operating point) + - Threshold curves (LER vs p for each decoder, grouped by distance) + - Per-round fitting (when multiple duration multipliers are present) + +Writes an analysis JSON that ``build_report.py`` consumes. + +Example: + uv run python examples/surface/analyze_data.py results/data.json + uv run python examples/surface/analyze_data.py shard1.json shard2.json -o analysis/ +""" + +from __future__ import annotations + +import argparse +import json +import math +from dataclasses import asdict, dataclass, field +from pathlib import Path + +# -- Analysis data model ------------------------------------------------------ + + +@dataclass +class ComparisonRow: + """One decoder's stats at one operating point.""" + + decoder: str + distance: int + basis: str + physical_error_rate: float + num_rounds: int + num_shots: int + num_errors: int + logical_error_rate: float + ci_low: float + ci_high: float + per_shot_mean: float + per_shot_median: float + per_shot_p99: float + per_shot_max: float + quantiles: list[float] = field(default_factory=list) + + +@dataclass +class ComparisonTable: + """All decoder rows for one (distance, p, rounds) point, sorted by LER.""" + + distance: int + basis: str + physical_error_rate: float + num_rounds: int + num_shots: int + rows: list[ComparisonRow] + + +@dataclass +class ThresholdCurvePoint: + """One (p, LER) point on a threshold curve.""" + + physical_error_rate: float + # LER over d rounds (either projected from fit, or raw at r=2d) + logical_error_rate: float + ci_low: float + ci_high: float + num_shots: int + num_errors: int + # Per-round fitted epsilon (when multiple round counts available) + fitted_epsilon: float | None = None + fitted_epsilon_ci_low: float | None = None + fitted_epsilon_ci_high: float | None = None + num_round_points: int = 1 + # Per-round LER (= fitted_epsilon when fitted, else raw_LER / num_rounds) + per_round_ler: float | None = None + per_round_ci_low: float | None = None + per_round_ci_high: float | None = None + + +@dataclass +class ThresholdCurve: + """LER vs p for one (decoder, distance, basis) combination. + + When multiple round counts are available, the threshold points use + fitted per-round epsilon from p_L(r) = 0.5*(1-(1-2*eps)^r). + """ + + decoder: str + distance: int + basis: str + points: list[ThresholdCurvePoint] + uses_fitted_epsilon: bool = False + + +@dataclass +class DurationCurvePoint: + """One (rounds, LER) point on a duration curve.""" + + num_rounds: int + logical_error_rate: float + ci_low: float + ci_high: float + num_shots: int + num_errors: int + + +@dataclass +class DurationCurve: + """LER vs rounds for one (decoder, distance, basis, p) combination.""" + + decoder: str + distance: int + basis: str + physical_error_rate: float + points: list[DurationCurvePoint] + + +@dataclass +class ThresholdEstimate: + """Estimated threshold from curve crossing for one decoder. + + metric: "per_round" or "d_round" indicating which LER was used for the crossing. + """ + + decoder: str + basis: str + estimated_p_th: float + d_small: int + d_large: int + metric: str = "per_round" # "per_round", "d_round", or "fss" + std_error: float | None = None + + +@dataclass +class AnalysisResult: + """Full analysis output.""" + + config: dict + comparison_tables: list[ComparisonTable] = field(default_factory=list) + threshold_curves: list[ThresholdCurve] = field(default_factory=list) + duration_curves: list[DurationCurve] = field(default_factory=list) + threshold_estimates: list[ThresholdEstimate] = field(default_factory=list) + + +# -- Wilson score interval ---------------------------------------------------- + + +def _wilson_ci(n: int, k: int, z: float = 1.96) -> tuple[float, float]: + """95% Wilson score confidence interval for binomial proportion.""" + if n == 0: + return 0.0, 0.0 + p = k / n + if p == 0: + return 0.0, 1 - (1 - 0.95) ** (1 / n) # Clopper-Pearson upper for 0 successes + if p == 1: + return (1 - 0.95) ** (1 / n), 1.0 + denom = 1 + z * z / n + centre = (p + z * z / (2 * n)) / denom + half = z * math.sqrt(p * (1 - p) / n + z * z / (4 * n * n)) / denom + return max(0.0, centre - half), min(1.0, centre + half) + + +# -- Per-round epsilon fitting ------------------------------------------------ + + +def _ler_model(epsilon: float, r: int) -> float: + """p_L(r) = 0.5 * (1 - (1 - 2*epsilon)^r).""" + if epsilon <= 0 or epsilon >= 0.5: + return 0.5 + return 0.5 * (1.0 - (1.0 - 2.0 * epsilon) ** r) + + +def _fit_epsilon(round_values: list[int], ler_values: list[float]) -> float | None: + """Fit per-round epsilon from (rounds, LER) pairs using golden section search. + + Minimises sum of squared residuals of p_L(r) = 0.5*(1-(1-2*eps)^r). + Returns None if fitting is not possible. + """ + if not round_values or all(v == 0 for v in ler_values): + return None + + def cost(eps: float) -> float: + return sum((ler - _ler_model(eps, r)) ** 2 for r, ler in zip(round_values, ler_values, strict=True)) + + # Golden section search on [1e-8, 0.499] + a, b = 1e-8, 0.499 + gr = (math.sqrt(5) + 1) / 2 + for _ in range(80): + c = b - (b - a) / gr + d = a + (b - a) / gr + if cost(c) < cost(d): + b = d + else: + a = c + return (a + b) / 2 + + +# -- Load and merge shards ---------------------------------------------------- + + +def _load_shards(paths: list[Path]) -> tuple[dict, list[dict]]: + """Load JSON shards and return (merged_config, all_points).""" + all_points = [] + config = {} + for path in paths: + data = json.loads(path.read_text()) + if not config: + config = dict(data.get("config", {})) + all_points.extend(data.get("points", [])) + + # Derive config fields from actual data (shards may cover different subsets) + all_decoders = set() + all_distances = set() + all_error_rates = set() + total_shots = 0 + for pt in all_points: + all_distances.add(pt["distance"]) + all_error_rates.add(pt["physical_error_rate"]) + total_shots = max(total_shots, pt.get("num_shots", 0)) + for ds in pt.get("decoder_stats", []): + all_decoders.add(ds["decoder"]) + config["decoders"] = sorted(all_decoders) + config["distances"] = sorted(all_distances) + config["error_rates"] = sorted(all_error_rates) + if total_shots: + config["shots"] = total_shots + return config, all_points + + +# -- Analysis ----------------------------------------------------------------- + + +def analyze(config: dict, points: list[dict]) -> AnalysisResult: + """Compute comparison tables and threshold curves from raw data points.""" + result = AnalysisResult(config=config) + + # Group points by (distance, basis, p, rounds) + from collections import defaultdict + + by_cell: dict[tuple, list[dict]] = defaultdict(list) + for pt in points: + key = (pt["distance"], pt["basis"], pt["physical_error_rate"], pt["num_rounds"]) + by_cell[key].append(pt) + + # Comparison tables: one per (distance, p, rounds) cell + for (d, basis, p, r), cell_points in sorted(by_cell.items()): + # Merge decoder stats across shards for same cell + decoder_stats: dict[str, dict] = {} + total_shots = 0 + for pt in cell_points: + total_shots += pt["num_shots"] + for ds in pt.get("decoder_stats", []): + name = ds["decoder"] + if name not in decoder_stats: + decoder_stats[name] = { + "num_errors": 0, + "num_shots": 0, + "per_shot_mean": ds["per_shot_mean"], + "per_shot_median": ds["per_shot_median"], + "per_shot_p99": ds["per_shot_p99"], + "per_shot_max": ds["per_shot_max"], + "quantiles": ds.get("quantiles", []), + } + decoder_stats[name]["num_errors"] += ds["num_errors"] + decoder_stats[name]["num_shots"] += pt["num_shots"] + + rows = [] + for dec_name, stats in decoder_stats.items(): + n = stats["num_shots"] + k = stats["num_errors"] + ler = k / n if n > 0 else 0.0 + ci_lo, ci_hi = _wilson_ci(n, k) + rows.append( + ComparisonRow( + decoder=dec_name, + distance=d, + basis=basis, + physical_error_rate=p, + num_rounds=r, + num_shots=n, + num_errors=k, + logical_error_rate=ler, + ci_low=ci_lo, + ci_high=ci_hi, + per_shot_mean=stats["per_shot_mean"], + per_shot_median=stats["per_shot_median"], + per_shot_p99=stats["per_shot_p99"], + per_shot_max=stats["per_shot_max"], + quantiles=stats.get("quantiles", []), + ), + ) + + rows.sort(key=lambda r: r.logical_error_rate) + + result.comparison_tables.append( + ComparisonTable( + distance=d, + basis=basis, + physical_error_rate=p, + num_rounds=r, + num_shots=total_shots, + rows=rows, + ), + ) + + # Threshold curves: group by (decoder, distance, basis) across all rounds. + # For each p, if multiple round counts exist, fit per-round epsilon. + # Otherwise, use the raw LER at the single available round count. + tc_groups: dict[tuple, dict[float, list[ComparisonRow]]] = defaultdict(lambda: defaultdict(list)) + for table in result.comparison_tables: + for row in table.rows: + key = (row.decoder, row.distance, row.basis) + tc_groups[key][row.physical_error_rate].append(row) + + for (dec, d, basis), p_to_rows in sorted(tc_groups.items()): + curve_points = [] + has_fitting = False + for p in sorted(p_to_rows): + rows = p_to_rows[p] + if len(rows) >= 2: + # Multiple round counts: fit per-round epsilon + round_vals = [r.num_rounds for r in rows] + ler_vals = [r.logical_error_rate for r in rows] + eps = _fit_epsilon(round_vals, ler_vals) + if eps is not None: + has_fitting = True + # Project to d-round LER for display + projected_ler = _ler_model(eps, d) + # CI from fitting upper/lower LER bounds + ci_lo_vals = [r.ci_low for r in rows] + ci_hi_vals = [r.ci_high for r in rows] + eps_lo = _fit_epsilon(round_vals, ci_hi_vals) # higher LER -> higher eps + eps_hi = _fit_epsilon(round_vals, ci_lo_vals) # lower LER -> lower eps + total_shots = sum(r.num_shots for r in rows) + total_errors = sum(r.num_errors for r in rows) + proj_ci_lo = _ler_model(eps_hi, d) if eps_hi else projected_ler + proj_ci_hi = _ler_model(eps_lo, d) if eps_lo else projected_ler + curve_points.append( + ThresholdCurvePoint( + physical_error_rate=p, + logical_error_rate=projected_ler, + ci_low=proj_ci_lo, + ci_high=proj_ci_hi, + num_shots=total_shots, + num_errors=total_errors, + fitted_epsilon=eps, + fitted_epsilon_ci_low=eps_hi, + fitted_epsilon_ci_high=eps_lo, + num_round_points=len(rows), + per_round_ler=eps, + per_round_ci_low=eps_hi, + per_round_ci_high=eps_lo, + ), + ) + continue + + # Single round count: use raw LER, estimate per-round from + # p_L(r) = 0.5*(1-(1-2*eps)^r) inverted. + row = rows[0] + raw_per_round = _fit_epsilon([row.num_rounds], [row.logical_error_rate]) + raw_pr_lo = _fit_epsilon([row.num_rounds], [row.ci_high]) + raw_pr_hi = _fit_epsilon([row.num_rounds], [row.ci_low]) + curve_points.append( + ThresholdCurvePoint( + physical_error_rate=row.physical_error_rate, + logical_error_rate=row.logical_error_rate, + ci_low=row.ci_low, + ci_high=row.ci_high, + num_shots=row.num_shots, + num_errors=row.num_errors, + per_round_ler=raw_per_round, + per_round_ci_low=raw_pr_hi, + per_round_ci_high=raw_pr_lo, + ), + ) + + result.threshold_curves.append( + ThresholdCurve( + decoder=dec, + distance=d, + basis=basis, + points=curve_points, + uses_fitted_epsilon=has_fitting, + ), + ) + + # Duration curves: LER vs rounds for each (decoder, distance, basis, p). + # Only meaningful when multiple round counts exist per (d, p). + dur_groups: dict[tuple, list[ComparisonRow]] = defaultdict(list) + for table in result.comparison_tables: + for row in table.rows: + key = (row.decoder, row.distance, row.basis, row.physical_error_rate) + dur_groups[key].append(row) + + for (dec, d, basis, p), rows in sorted(dur_groups.items()): + if len(rows) < 2: + continue # need at least 2 round counts + dur_points = [ + DurationCurvePoint( + num_rounds=row.num_rounds, + logical_error_rate=row.logical_error_rate, + ci_low=row.ci_low, + ci_high=row.ci_high, + num_shots=row.num_shots, + num_errors=row.num_errors, + ) + for row in sorted(rows, key=lambda r: r.num_rounds) + ] + result.duration_curves.append( + DurationCurve( + decoder=dec, + distance=d, + basis=basis, + physical_error_rate=p, + points=dur_points, + ), + ) + + # Threshold estimates: find where smallest/largest distance curves cross. + # Compute for both per-round LER and d-round LER. + import itertools as _itertools + + # Threshold estimates via FSS fit (Wang-Harrington-Preskill form). + # Uses ALL (p, d, per_round_ler) points across ALL distances simultaneously. + # Falls back to pairwise crossing only as a seed for the FSS fit. + est_groups: dict[tuple, list[ThresholdCurve]] = defaultdict(list) + for curve in result.threshold_curves: + est_groups[(curve.decoder, curve.basis)].append(curve) + + def _crude_crossing_seed(dec_curves: list[ThresholdCurve]) -> float | None: + """Quick pairwise crossing of smallest/largest distance for FSS seed.""" + distances = sorted({c.distance for c in dec_curves}) + if len(distances) < 2: + return None + small = next(c for c in dec_curves if c.distance == distances[0]) + large = next(c for c in dec_curves if c.distance == distances[-1]) + small_by_p = { + pt.physical_error_rate: (pt.per_round_ler or pt.logical_error_rate) + for pt in small.points + if (pt.per_round_ler or pt.logical_error_rate) and (pt.per_round_ler or pt.logical_error_rate) > 0 + } + large_by_p = { + pt.physical_error_rate: (pt.per_round_ler or pt.logical_error_rate) + for pt in large.points + if (pt.per_round_ler or pt.logical_error_rate) and (pt.per_round_ler or pt.logical_error_rate) > 0 + } + shared_ps = sorted(set(small_by_p) & set(large_by_p)) + diffs = [(p, large_by_p[p] - small_by_p[p]) for p in shared_ps] + for (p0, diff0), (p1, diff1) in _itertools.pairwise(diffs): + if diff0 == 0.0: + return p0 + if diff0 * diff1 < 0.0: + t = abs(diff0) / (abs(diff0) + abs(diff1)) + return math.exp((1.0 - t) * math.log(p0) + t * math.log(p1)) + return None + + for (dec, basis), dec_curves in sorted(est_groups.items()): + distances = sorted({c.distance for c in dec_curves}) + if len(distances) < 2: + continue + + # FSS fit for per-round LER + plist_pr, dlist_pr, plog_pr = [], [], [] + for curve in dec_curves: + for pt in curve.points: + pr = pt.per_round_ler + if pr and pr > 0: + plist_pr.append(pt.physical_error_rate) + dlist_pr.append(curve.distance) + plog_pr.append(pr) + + # FSS fit for d-round LER + plist_dr, dlist_dr, plog_dr = [], [], [] + for curve in dec_curves: + for pt in curve.points: + lr = pt.logical_error_rate + if lr and lr > 0: + plist_dr.append(pt.physical_error_rate) + dlist_dr.append(curve.distance) + plog_dr.append(lr) + + # Crude seed for FSS optimizer + seed = _crude_crossing_seed(dec_curves) + + for metric, plist, dlist, plog in [ + ("fss_per_round", plist_pr, dlist_pr, plog_pr), + ("fss_d_round", plist_dr, dlist_dr, plog_dr), + ]: + if len(plist) < 5 or len(set(dlist)) < 2: + continue + s = seed if seed is not None else sorted(plist)[len(plist) // 2] + fss = _fit_fss_threshold(plist, dlist, plog, seed_threshold=s) + if fss is not None: + result.threshold_estimates.append( + ThresholdEstimate( + decoder=dec, + basis=basis, + estimated_p_th=fss[0], + d_small=min(distances), + d_large=max(distances), + metric=metric, + std_error=fss[1], + ), + ) + + return result + + +def _fit_fss_threshold( + plist: list[float], + dlist: list[int], + plog: list[float], + *, + seed_threshold: float, + seed_nu: float = 1.0, + window_factor_low: float = 0.4, + window_factor_high: float = 2.0, +) -> tuple[float, float] | None: + """Fit the Wang-Harrington-Preskill FSS form using pecos.analysis.threshold_curve. + + Returns (p_th, p_th_std_error) or None if the fit fails. + """ + try: + from pecos.analysis.threshold_curve import func as fss_func + from pecos.analysis.threshold_curve import threshold_fit + except ImportError: + return None + + # Filter to a window around the seed threshold + low = seed_threshold * window_factor_low + high = seed_threshold * window_factor_high + indices = [i for i, p in enumerate(plist) if low <= p <= high and plog[i] > 0] + if len(indices) < 5 or len({dlist[i] for i in indices}) < 2: + return None + + import pecos as pc + + p_arr = pc.array([plist[i] for i in indices]) + d_arr = pc.array([float(dlist[i]) for i in indices]) + ler_arr = pc.array([plog[i] for i in indices]) + mean_ler = float(sum(plog[i] for i in indices) / len(indices)) + initial = [seed_threshold, seed_nu, mean_ler, 1.0, 1.0] + + try: + popt, stdev = threshold_fit(p_arr, d_arr, ler_arr, fss_func, initial) + except Exception: + return None + + p_th = float(popt[0]) + p_th_se = float(stdev[0]) + if p_th <= 0: + return None + return (p_th, p_th_se) + + +# -- CLI ---------------------------------------------------------------------- + + +def main() -> int: + """CLI entry point for data analysis.""" + parser = argparse.ArgumentParser( + description=__doc__, + formatter_class=argparse.RawDescriptionHelpFormatter, + ) + parser.add_argument("shards", nargs="+", type=Path, help="JSON shard file(s) from generate_data.py") + parser.add_argument("-o", "--output-dir", type=str, default=None) + args = parser.parse_args() + + config, points = _load_shards(args.shards) + print(f"Loaded {len(points)} data points from {len(args.shards)} shard(s)") + + result = analyze(config, points) + print(f" {len(result.comparison_tables)} comparison tables") + print(f" {len(result.threshold_curves)} threshold curves") + + out = Path(args.output_dir) if args.output_dir else args.shards[0].parent + out.mkdir(parents=True, exist_ok=True) + json_path = out / "analysis.json" + json_path.write_text(json.dumps(asdict(result), indent=2)) + print(f"Wrote {json_path}") + + return 0 + + +if __name__ == "__main__": + raise SystemExit(main()) diff --git a/examples/surface/brickwork_sweep.py b/examples/surface/brickwork_sweep.py new file mode 100644 index 000000000..db23d9226 --- /dev/null +++ b/examples/surface/brickwork_sweep.py @@ -0,0 +1,794 @@ +r"""Brickwork circuit sweep: transversal gate performance across widths, depths, distances. + +Generates mirrored brickwork circuits (H + CX) at various configurations, +decodes with multiple decoders, and writes JSON results that can be fed +to ``build_report.py`` for HTML/PDF reports. + +The mirrored brickwork guarantees output = |0...0>, so logical errors +are unambiguous. + +Decoder names: + observable_subgraph:INNER -- OSD with inner decoder (pymatching, pecos_uf:fast, etc.) + logical_circuit:BUDGET:INNER -- LogicalCircuitDecoder (unlimited, windowed, 10ms, etc.) + logical_algorithm:INNER -- LogicalAlgorithmDecoder (full-circuit, no budget) + +Example: + uv run python examples/surface/brickwork_sweep.py \ + --distances 3 5 --widths 2 3 4 --depths 1 2 3 \ + --error-rates 0.001 0.002 \ + --decoders observable_subgraph:pymatching \ + --shots 5000 --output-dir /tmp/brickwork_sweep + + uv run python examples/surface/brickwork_sweep.py \ + --distances 3 5 --widths 2 3 --depths 1 2 \ + --error-rates 0.001 \ + --decoders observable_subgraph:pymatching logical_circuit:windowed:pymatching \ + --shots 2000 --save-html --open +""" + +from __future__ import annotations + +import argparse +import json +import random +import sys +import time +from dataclasses import asdict, dataclass, field +from pathlib import Path + +sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "python" / "quantum-pecos" / "src")) + + +# -- Data model --------------------------------------------------------------- + + +@dataclass +class DecoderResult: + decoder: str + num_errors: int + logical_error_rate: float + decode_seconds: float + + +@dataclass +class BrickworkPoint: + distance: int + width: int + depth: int + physical_error_rate: float + num_shots: int + seed: int + sample_seconds: float + decoder_results: list[DecoderResult] = field(default_factory=list) + + +@dataclass +class BrickworkShard: + config: dict + points: list[BrickworkPoint] = field(default_factory=list) + total_seconds: float = 0.0 + + +# -- Circuit builder ----------------------------------------------------------- + + +def build_mirrored_brickwork(width, depth, seed, patch, rounds=2): + """Build a mirrored brickwork circuit (identity, output = |0...0>).""" + from pecos.qec.surface import LogicalCircuitBuilder + + nq = patch.geometry.num_data + patch.geometry.num_ancilla + rng = random.Random(seed) + + b = LogicalCircuitBuilder() + labels = [f"Q{i}" for i in range(width)] + for i, label in enumerate(labels): + b.add_patch(patch, label, qubit_offset=i * nq) + + eff = dict.fromkeys(labels, "Z") + b.add_memory(labels, rounds, "Z") + + ops_forward = [] + for layer in range(depth): + layer_ops = [] + for label in labels: + if rng.random() < 0.5: + b.add_transversal_h(label) + eff[label] = "X" if eff[label] == "Z" else "Z" + layer_ops.append(("H", label)) + b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + + offset = layer % 2 + cx_applied = [] + for i in range(offset, width - 1, 2): + ctrl, tgt = labels[i], labels[i + 1] + if eff[ctrl] == eff[tgt]: + b.add_transversal_cx(ctrl, tgt) + cx_applied.append((ctrl, tgt)) + if cx_applied: + b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + layer_ops.append(("CX", cx_applied)) + ops_forward.append(layer_ops) + + # Mirror + for layer_ops in reversed(ops_forward): + for op_type, *args in reversed(layer_ops): + if op_type == "CX": + for ctrl, tgt in reversed(args[0]): + if eff[ctrl] == eff[tgt]: + b.add_transversal_cx(ctrl, tgt) + b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + for op_type, *args in reversed(layer_ops): + if op_type == "H": + label = args[0] + b.add_transversal_h(label) + eff[label] = "X" if eff[label] == "Z" else "Z" + b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + + return b + + +def build_t_injection_circuit(distance, seed, patch, rounds_per_layer): + """Build a T-gate injection circuit: memory + T injection + memory.""" + from pecos.qec.surface import LogicalCircuitBuilder + + nq = patch.geometry.num_data + patch.geometry.num_ancilla + b = LogicalCircuitBuilder() + b.add_patch(patch, "D", qubit_offset=0) + b.add_patch(patch, "A", qubit_offset=nq) + + # Memory → T injection → Memory + rounds = max(rounds_per_layer, distance) + b.add_memory(["D", "A"], rounds=rounds, basis="Z") + b.add_t_via_injection("D", "A", rounds_before=rounds, rounds_after=rounds) + return b + + +# -- Sweep -------------------------------------------------------------------- + + +def run_sweep( + *, + distances: list[int], + widths: list[int], + depths: list[int], + error_rates: list[float], + decoders: list[str], + shots: int, + circuit_seed: int, + rounds_per_layer: int, +) -> BrickworkShard: + """Run the full brickwork sweep.""" + from pecos.qec.surface import SurfacePatch + from pecos_rslib.qec import ObservableSubgraphDecoder, ParsedDem + + config = { + "distances": distances, + "widths": widths, + "depths": depths, + "error_rates": error_rates, + "decoders": decoders, + "shots": shots, + "circuit_seed": circuit_seed, + "rounds_per_layer": rounds_per_layer, + } + + shard = BrickworkShard(config=config) + t_total = time.perf_counter() + + total_cells = len(distances) * len(widths) * len(depths) * len(error_rates) + cell_idx = 0 + + for d in distances: + patch = SurfacePatch.create(distance=d) + for w in widths: + for depth in depths: + # Build circuit once per (d, w, depth) — reuse across error rates + b = build_mirrored_brickwork(w, depth, circuit_seed, patch, rounds_per_layer) + sc = b.stab_coords() + + for p in error_rates: + cell_idx += 1 + print(f"[{cell_idx}/{total_cells}] d={d} w={w} depth={depth} p={p:.4g} ...", end=" ", flush=True) + + dem_str = b.build_dem(p1=p, p2=p, p_meas=p, p_prep=p) + + # Sample + t0 = time.perf_counter() + parsed = ParsedDem.from_string(dem_str) + rust_sampler = parsed.to_dem_sampler() + batch = rust_sampler.generate_samples(shots, seed=circuit_seed + cell_idx) + sample_sec = time.perf_counter() - t0 + + point = BrickworkPoint( + distance=d, + width=w, + depth=depth, + physical_error_rate=p, + num_shots=shots, + seed=circuit_seed, + sample_seconds=sample_sec, + ) + + # Decode with each decoder + for decoder_name in decoders: + t0 = time.perf_counter() + if decoder_name.startswith("logical_circuit"): + from pecos_rslib.qec import LogicalCircuitDecoder + + # Format: logical_circuit:budget:inner + parts = decoder_name.split(":") + budget = parts[1] if len(parts) > 1 else "offline" + inner = parts[2] if len(parts) > 2 else "pymatching" + desc = b.build_algorithm_descriptor(p1=p, p2=p, p_meas=p, p_prep=p) + dec = LogicalCircuitDecoder(desc, budget, inner) + errors = dec.decode_count(batch) + elif decoder_name.startswith("logical_algorithm"): + from pecos_rslib.qec import LogicalAlgorithmDecoder + + parts = decoder_name.split(":", 1) + inner = parts[1] if len(parts) > 1 else "pymatching" + desc = b.build_algorithm_descriptor(p1=p, p2=p, p_meas=p, p_prep=p) + algo = LogicalAlgorithmDecoder(desc, inner) + errors = algo.decode_count(batch) + elif decoder_name.startswith("observable_subgraph"): + parts = decoder_name.split(":", 1) + inner = parts[1] if len(parts) > 1 else "pymatching" + osd = ObservableSubgraphDecoder(dem_str, sc, inner) + # Use parallel decode for large shot counts + if shots >= 5000: + errors = osd.decode_count_parallel(batch, dem_str, sc, inner) + else: + errors = osd.decode_count(batch) + else: + msg = ( + f"Unknown decoder: '{decoder_name}'. " + f"Supported: observable_subgraph:INNER, " + f"logical_circuit:BUDGET:INNER, " + f"logical_algorithm:INNER" + ) + raise ValueError(msg) + dec_sec = time.perf_counter() - t0 + ler = errors / shots + + point.decoder_results.append( + DecoderResult( + decoder=decoder_name, + num_errors=errors, + logical_error_rate=ler, + decode_seconds=dec_sec, + ) + ) + + shard.points.append(point) + lers = {r.decoder: f"{r.logical_error_rate:.5f}" for r in point.decoder_results} + print(f"LER={lers}") + + shard.total_seconds = time.perf_counter() - t_total + return shard + + +# -- HTML report --------------------------------------------------------------- + + +def write_html_report(shard: BrickworkShard, path: Path, coherent_results=None) -> None: + """Write an HTML report from the sweep results.""" + from collections import defaultdict + + # Group by (width, depth) for each distance + tables = defaultdict(list) + for pt in shard.points: + tables[(pt.distance, pt.physical_error_rate)].append(pt) + + style = """ + :root { + color-scheme: light dark; + --bg: #f8fafc; --fg: #0f172a; + --hero-bg: linear-gradient(135deg, #e0f2fe, #f8fafc 55%, #dcfce7); + --card-bg: white; --card-border: #dbeafe; --card-shadow: rgba(15,23,42,0.05); + --meta-bg: rgba(255,255,255,0.82); + --muted: #475569; --link: #2563eb; + --table-stripe: #f1f5f9; --table-border: #e2e8f0; + --good: #16a34a; --warn: #ea580c; --bad: #dc2626; + } + @media (prefers-color-scheme: dark) { + :root { + --bg: #0f172a; --fg: #e2e8f0; + --hero-bg: linear-gradient(135deg, #1e293b, #0f172a 55%, #1a2e1a); + --card-bg: #1e293b; --card-border: #334155; --card-shadow: rgba(0,0,0,0.3); + --meta-bg: rgba(30,41,59,0.82); + --muted: #94a3b8; --link: #60a5fa; + --table-stripe: #0f172a; --table-border: #334155; + --good: #4ade80; --warn: #fb923c; --bad: #f87171; + } + } + body { + margin: 0; + font-family: ui-sans-serif, -apple-system, BlinkMacSystemFont, sans-serif; + background: var(--bg); color: var(--fg); + } + main { max-width: 1100px; margin: 0 auto; padding: 32px 24px 56px; } + h1, h2, h3, p { margin-top: 0; } + .hero { + background: var(--hero-bg); + border: 1px solid var(--card-border); + border-radius: 20px; + padding: 28px 32px; + margin-bottom: 24px; + } + .hero h1 { font-size: 1.6rem; margin-bottom: 0.3em; } + .hero p { color: var(--muted); margin: 0; } + .meta { + display: grid; + grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); + gap: 12px; + margin-top: 18px; + } + .meta-card { + background: var(--meta-bg); + border: 1px solid var(--card-border); + border-radius: 14px; + padding: 14px 16px; + } + .meta-card strong { + display: block; font-size: 0.78rem; text-transform: uppercase; + letter-spacing: 0.04em; color: var(--muted); margin-bottom: 4px; + } + .section { + background: var(--card-bg); + border: 1px solid var(--card-border); + border-radius: 18px; + padding: 22px 26px; + margin-top: 20px; + box-shadow: 0 10px 24px var(--card-shadow); + overflow-x: auto; + } + .section h2 { font-size: 1.15rem; margin-bottom: 0.3em; } + .section h3 { font-size: 0.95rem; color: var(--muted); } + .section p { font-size: 0.9rem; color: var(--muted); } + table { border-collapse: collapse; width: 100%; margin: 12px 0 0; } + th, td { padding: 10px 14px; text-align: right; border-bottom: 1px solid var(--table-border); } + th { + font-size: 0.78rem; text-transform: uppercase; + letter-spacing: 0.03em; color: var(--muted); border-bottom-width: 2px; + } + td:first-child, th:first-child { text-align: left; } + tr:nth-child(even) td { background: var(--table-stripe); } + .good { color: var(--good); font-weight: 600; } + .warn { color: var(--warn); font-weight: 600; } + .bad { color: var(--bad); font-weight: 600; } + code { + font-family: ui-monospace, SFMono-Regular, Menlo, monospace; + font-size: 0.85em; background: var(--table-stripe); + padding: 0.15em 0.4em; border-radius: 3px; + } + details.info { + background: var(--card-bg); + border: 1px solid var(--card-border); + border-radius: 18px; + margin-top: 20px; + box-shadow: 0 10px 24px var(--card-shadow); + } + details.info > summary { + cursor: pointer; font-size: 0.95rem; font-weight: 600; + padding: 16px 26px; list-style: none; + } + details.info > summary::before { content: "\\25B6\\00a0\\00a0"; font-size: 0.75em; } + details.info[open] > summary::before { content: "\\25BC\\00a0\\00a0"; } + details.info .content { + padding: 0 26px 22px; line-height: 1.7; font-size: 0.9rem; + } + details.info .content h4 { margin: 1em 0 0.3em; } + """ + + # Build meta cards + distances = sorted({pt.distance for pt in shard.points}) if shard.points else [] + decoders_used = sorted({r.decoder for pt in shard.points for r in pt.decoder_results}) + + meta_cards = [] + if distances: + meta_cards.append( + f'
Distances{", ".join(str(d) for d in distances)}
' + ) + if decoders_used: + meta_cards.append(f'
Decoders{len(decoders_used)}
') + if shard.points: + meta_cards.append(f'
Shots{shard.points[0].num_shots:,}
') + meta_cards.append(f'
Time{shard.total_seconds:.1f}s
') + + html_parts = [ + "", + '', + '', + '', + "PECOS Surface Code Report", + f"", + "
", + '
', + "

PECOS Surface Code Report

", + "

Mirrored brickwork circuits, T-gate injection, and coherent noise analysis

", + f'
{" ".join(meta_cards)}
', + "
", + "", + '
Decoding Concepts: Throughput, Reaction Time, and Budgets', + '
', + "

Throughput (avoiding backlog)

", + "

The decoder must process syndrome data at least as fast as the hardware " + "generates it. If syndrome extraction takes Tcycle per round, the " + "decoder must process each round in ≤ Tcycle on average. If it " + "falls behind, a backlog accumulates, causing exponential slowdown of " + "the quantum computation.

", + "", + "

Reaction time

", + "

At feed-forward decision points (T-gate injection, magic state consumption), " + "the physical hardware waits for the decoder to produce a correction. The " + "reaction time is the time available between the last syndrome arriving " + "and the correction being applied. For Clifford-only circuits " + "(like these brickwork circuits), there are no mid-circuit decisions — the " + "Pauli frame is metadata applied at the final measurement. The reaction time is " + "effectively unlimited.

", + "", + "

Budget strategies

", + "

The decoder framework selects a strategy based on the user-specified reaction " "time budget:

", + "
    ", + "
  • unlimited — Full-circuit OSD. Maximum accuracy. " + "Appropriate for Clifford circuits or offline analysis.
    • ", + "
  • windowed / 10ms — Windowed OSD with " + "overlap buffers inside each per-observable subgraph. Bounded latency, full " + "accuracy with sufficient overlap.
    • ", + "
  • 100us / 1us — Tight budget. Windowed " + "without overlap. Accuracy degrades; requires advanced techniques (ghost " + "protocol) for improvement.
    • ", + "
", + "", + "

Compute hardware

", + "

The budget is a constraint, not a measurement. A decode that takes " + "300μs on a CPU might take 30μs on an FPGA. The strategy doesn't change " + "— only whether it fits within the budget on a given compute platform. " + "Profiling on the target hardware determines feasibility.

", + "", + "

References

", + "
    ", + "
  • Riverlane + Rigetti (arXiv:2410.05202): 9.6μs response time, backlog definition
    • ", + "
  • Cain et al. (arXiv:2505.13587): software commitment, <100μs at d=25
    • ", + "
  • Turner et al. (arXiv:2505.23567): ghost protocol for scalable windowed decoding
    • ", + "
  • Serra-Peralta et al. (arXiv:2505.13599): per-observable subgraph MWPM
    • ", + "
", + "
", + "", + ] + + # Separate brickwork and T-injection points + brickwork_tables = defaultdict(list) + t_injection_tables = defaultdict(list) + for pt in shard.points: + if pt.depth == 0: # T-injection marker + t_injection_tables[(pt.distance, pt.physical_error_rate)].append(pt) + else: + brickwork_tables[(pt.distance, pt.physical_error_rate)].append(pt) + + if brickwork_tables: + html_parts.append('
') + html_parts.append("

Brickwork Circuits (Clifford)

") + html_parts.append( + "

Mirrored random gate sequences (identity operation). " + "LER from stochastic depolarizing noise only.

" + ) + + for (d, p), points in sorted(brickwork_tables.items()): + html_parts.append(f"

d={d}, p={p}

") + + decoders = sorted({r.decoder for pt in points for r in pt.decoder_results}) + html_parts.append("") + for dec in decoders: + html_parts.append(f"") + html_parts.append("") + + for pt in sorted(points, key=lambda x: (x.width, x.depth)): + html_parts.append(f"") + for dec in decoders: + r = next((r for r in pt.decoder_results if r.decoder == dec), None) + if r: + cls = "good" if r.logical_error_rate < 0.01 else "warn" if r.logical_error_rate < 0.05 else "bad" + html_parts.append( + f'", + ) + else: + html_parts.append("") + html_parts.append("") + html_parts.append("
WidthDepth{dec}
{pt.width}{pt.depth}{r.logical_error_rate:.5f} ' f"({r.decode_seconds:.2f}s)-
") + + if brickwork_tables: + html_parts.append("
") + + if t_injection_tables: + html_parts.append('
') + html_parts.append("

T-Gate Injection (Non-Clifford)

") + html_parts.append( + "

T gate via magic state teleportation: " + "|T⟩ ancilla + CX + measure + conditional S. " + "Feed-forward decision point for the decoder.

" + ) + + for (d, p), points in sorted(t_injection_tables.items()): + decoders = sorted({r.decoder for pt in points for r in pt.decoder_results}) + html_parts.append(f"

d={d}, p={p}

") + html_parts.append("") + for dec in decoders: + html_parts.append(f"") + html_parts.append("") + + for pt in points: + html_parts.append("") + for dec in decoders: + r = next((r for r in pt.decoder_results if r.decoder == dec), None) + if r: + cls = "good" if r.logical_error_rate < 0.01 else "warn" if r.logical_error_rate < 0.05 else "bad" + html_parts.append( + f'", + ) + else: + html_parts.append("") + html_parts.append("") + html_parts.append("
Circuit{dec}
T-injection{r.logical_error_rate:.5f} ' f"({r.decode_seconds:.2f}s)-
") + + if t_injection_tables: + html_parts.append("
") + + # Coherent noise section + if coherent_results: + html_parts.append('
') + html_parts.append("

Coherent Idle Noise (X-basis Memory)

") + html_parts.append( + "

RZ(θ) rotation on both qubits after each CX gate models " + "uncompensated phase accumulation during idle time. Unlike stochastic " + "Z errors, coherent rotations accumulate constructively — the LER " + "far exceeds the Pauli-twirled equivalent sin²(θ/2). " + "Decoder uses a stochastic-only DEM. Simulated with StateVec.

" + ) + + for (d, p), result in sorted(coherent_results.items()): + html_parts.append(f"

d={d}, p_depol={p}

") + html_parts.append( + "" + "" + "" + "" + "" + "" + "" + "" + ) + for pt in result.points: + cls = "good" if pt.ler < 0.02 else "warn" if pt.ler < 0.05 else "bad" + amplification = ( + f"{pt.ler / result.points[0].ler:.1f}x" if result.points[0].ler > 0 and pt.p_idle > 0 else "" + ) + html_parts.append( + f'' + f"" + f'' + f"" + f"" + f"", + ) + html_parts.append("
θ (rad)sin²(θ/2)LER± SEErrorsvs baseline
{pt.p_idle:.3f}{pt.p_twirled:.5f}{pt.ler:.4f}{pt.standard_error:.4f}{pt.errors}/{pt.shots}{amplification}
") + + html_parts.append("
") + + html_parts.append("
") + path.write_text("\n".join(html_parts)) + print(f"Report written to {path}") + + +# -- CLI ----------------------------------------------------------------------- + + +def main(): + parser = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter) + parser.add_argument("--distances", type=int, nargs="+", default=[3, 5]) + parser.add_argument("--widths", type=int, nargs="+", default=[2, 3, 4]) + parser.add_argument("--depths", type=int, nargs="+", default=[1, 2, 3]) + parser.add_argument( + "--scaled-depth", action="store_true", help="Override --depths: set depth=2^((d+1)/2) per distance" + ) + parser.add_argument("--error-rates", type=float, nargs="+", default=[0.001]) + parser.add_argument("--decoders", nargs="+", default=["observable_subgraph:pymatching"]) + parser.add_argument("--shots", type=int, default=5000) + parser.add_argument("--seed", type=int, default=42) + parser.add_argument("--rounds-per-layer", type=int, default=2) + parser.add_argument( + "--include-t-injection", action="store_true", help="Include T-gate injection circuits (non-Clifford)" + ) + parser.add_argument( + "--t-injection-only", action="store_true", help="Only T-gate injection circuits (skip brickwork)" + ) + parser.add_argument( + "--include-coherent-noise", action="store_true", help="Include coherent idle noise sweep (RZ after CX)" + ) + parser.add_argument( + "--coherent-p-idle", + type=float, + nargs="+", + default=[0.0, 0.01, 0.03, 0.05, 0.07, 0.1], + help="Coherent idle RZ angles to sweep", + ) + parser.add_argument("--coherent-shots", type=int, default=None, help="Shots for coherent noise (default: --shots)") + parser.add_argument("--output-dir", type=Path, default=Path("/tmp/brickwork_sweep")) + parser.add_argument("--save-json", action="store_true") + parser.add_argument("--save-html", action="store_true") + parser.add_argument("--open", action="store_true") + args = parser.parse_args() + + if args.t_injection_only: + shard = BrickworkShard( + config={ + "distances": args.distances, + "error_rates": args.error_rates, + "decoders": args.decoders, + "shots": args.shots, + "t_injection_only": True, + }, + ) + elif args.scaled_depth: + # Per-distance depth: 2^((d+1)/2) — challenges the decoder proportionally + # d=3→4, d=5→8, d=7→16, d=9→32 + depths = [int(2 ** ((d + 1) / 2)) for d in args.distances] + print(f"Scaled depths: {dict(zip(args.distances, depths))}") + + all_points = [] + for d, depth in zip(args.distances, depths): + partial = run_sweep( + distances=[d], + widths=args.widths, + depths=[depth], + error_rates=args.error_rates, + decoders=args.decoders, + shots=args.shots, + circuit_seed=args.seed, + rounds_per_layer=args.rounds_per_layer, + ) + all_points.extend(partial.points) + shard = BrickworkShard( + config={ + "distances": args.distances, + "widths": args.widths, + "scaled_depths": dict(zip(args.distances, depths)), + "error_rates": args.error_rates, + "decoders": args.decoders, + "shots": args.shots, + }, + points=all_points, + ) + else: + shard = run_sweep( + distances=args.distances, + widths=args.widths, + depths=args.depths, + error_rates=args.error_rates, + decoders=args.decoders, + shots=args.shots, + circuit_seed=args.seed, + rounds_per_layer=args.rounds_per_layer, + ) + + # T-injection circuits + if args.include_t_injection or args.t_injection_only: + from pecos.qec.surface import SurfacePatch + from pecos_rslib.qec import ObservableSubgraphDecoder, ParsedDem + + print("\n--- T-Injection Circuits ---") + for d in args.distances: + patch = SurfacePatch.create(distance=d) + for p in args.error_rates: + b = build_t_injection_circuit(d, args.seed, patch, args.rounds_per_layer) + sc = b.stab_coords() + dem_str = b.build_dem(p1=p, p2=p, p_meas=p, p_prep=p) + parsed = ParsedDem.from_string(dem_str) + batch = parsed.to_dem_sampler().generate_samples(args.shots, seed=args.seed) + + point = BrickworkPoint( + distance=d, + width=2, + depth=0, # depth=0 signals T-injection + physical_error_rate=p, + num_shots=args.shots, + seed=args.seed, + sample_seconds=0, + ) + + for decoder_name in args.decoders: + t0 = time.perf_counter() + if decoder_name.startswith("logical_circuit"): + from pecos_rslib.qec import LogicalCircuitDecoder + + parts = decoder_name.split(":") + budget = parts[1] if len(parts) > 1 else "unlimited" + inner = parts[2] if len(parts) > 2 else "pymatching" + desc = b.build_algorithm_descriptor(p1=p, p2=p, p_meas=p, p_prep=p) + dec = LogicalCircuitDecoder(desc, budget, inner) + errors = dec.decode_count(batch) + elif decoder_name.startswith("logical_algorithm"): + from pecos_rslib.qec import LogicalAlgorithmDecoder + + parts = decoder_name.split(":", 1) + inner = parts[1] if len(parts) > 1 else "pymatching" + desc = b.build_algorithm_descriptor(p1=p, p2=p, p_meas=p, p_prep=p) + algo = LogicalAlgorithmDecoder(desc, inner) + errors = algo.decode_count(batch) + elif decoder_name.startswith("observable_subgraph"): + parts = decoder_name.split(":", 1) + inner = parts[1] if len(parts) > 1 else "pymatching" + osd = ObservableSubgraphDecoder(dem_str, sc, inner) + errors = osd.decode_count(batch) + else: + msg = ( + f"Unknown decoder: '{decoder_name}'. " + f"Supported: observable_subgraph:INNER, " + f"logical_circuit:BUDGET:INNER, " + f"logical_algorithm:INNER" + ) + raise ValueError(msg) + dec_sec = time.perf_counter() - t0 + ler = errors / args.shots + + point.decoder_results.append( + DecoderResult( + decoder=decoder_name, + num_errors=errors, + logical_error_rate=ler, + decode_seconds=dec_sec, + ) + ) + + shard.points.append(point) + lers = {r.decoder: f"{r.logical_error_rate:.5f}" for r in point.decoder_results} + print(f"d={d} T-injection p={p:.4g} ... LER={lers}") + + # Coherent noise sweep + coherent_results = None + if args.include_coherent_noise: + from coherent_noise_sweep import run_sweep as run_coherent_sweep + + coherent_shots = args.coherent_shots or args.shots + # StateVec is limited to d=3 (17 qubits). Skip larger distances. + coherent_distances = [d for d in args.distances if d <= 3] + if not coherent_distances: + print("\n--- Coherent Idle Noise: skipped (StateVec limited to d<=3) ---") + else: + print("\n--- Coherent Idle Noise ---") + coherent_results = {} + for d in coherent_distances: + for p in args.error_rates: + print(f"d={d} p={p:.4g}:") + result = run_coherent_sweep( + distance=d, + rounds=d, + basis="X", + p_depol=p, + p_idle_values=args.coherent_p_idle, + shots=coherent_shots, + seed=args.seed, + backend="statevec", + lazy_measure=True, + max_bond_dim=128, + ) + coherent_results[(d, p)] = result + + args.output_dir.mkdir(parents=True, exist_ok=True) + + if args.save_json: + json_path = args.output_dir / "brickwork_sweep_results.json" + json_path.write_text(json.dumps(asdict(shard), indent=2)) + print(f"JSON written to {json_path}") + + if args.save_html or args.open: + html_path = args.output_dir / "brickwork_sweep_report.html" + write_html_report(shard, html_path, coherent_results=coherent_results) + if args.open: + import webbrowser + + webbrowser.open(str(html_path)) + + +if __name__ == "__main__": + main() diff --git a/examples/surface/build_report.py b/examples/surface/build_report.py new file mode 100644 index 000000000..bfd9ce43c --- /dev/null +++ b/examples/surface/build_report.py @@ -0,0 +1,1591 @@ +r"""Build HTML and/or PDF reports from analysis JSON. + +Reads the analysis JSON produced by ``analyze_data.py`` and renders: + - HTML report with comparison tables + threshold curve plots (inline SVG) + - PDF report with the same content via matplotlib + +Example: + uv run python examples/surface/build_report.py results/analysis.json --html --pdf + uv run python examples/surface/build_report.py results/analysis.json --html --open +""" + +from __future__ import annotations + +import argparse +import html as html_mod +import json +import math +from collections import defaultdict +from pathlib import Path +from textwrap import dedent + +# -- Load analysis ------------------------------------------------------------ + + +def _load_analysis(path: Path) -> dict: + return json.loads(path.read_text()) + + +# -- Threshold curve SVG (inline) --------------------------------------------- + + +def _sci(v: float) -> str: + """Format a value in clean scientific notation for axis labels.""" + if v == 0: + return "0" + return f"{v:.1e}" + + +_COLORS = [ + "#2563eb", # blue + "#dc2626", # red + "#16a34a", # green + "#9333ea", # purple + "#ea580c", # orange + "#0891b2", # cyan + "#be185d", # pink + "#854d0e", # brown +] + +_DASH_PATTERNS = [ + "", # solid + "6,3", # dashed + "2,3", # dotted + "8,3,2,3", # dash-dot +] + + +def _build_threshold_svg( + curves: list[dict], + title: str, + width: int = 560, + height: int = 380, + color_by: str = "decoder", + threshold_p: float | None = None, + y_field: str = "logical_error_rate", + y_label: str = "Logical error rate", + decoder_color_map: dict[str, str] | None = None, + distance_color_map: dict[int, str] | None = None, +) -> str: + """Build an inline SVG plot of LER vs p for multiple (decoder, distance) curves. + + decoder_color_map / distance_color_map: fixed color assignments for + consistency across plots. When provided, overrides index-based coloring. + y_field: which field on each point to use for y-axis values. + Also uses "{y_field}" with "ci_low"/"ci_high" replaced accordingly. + threshold_p: if provided, draw a vertical dashed line at this p value. + color_by: "decoder" assigns colors by decoder (dashes by distance), + "distance" assigns colors by distance (dashes by decoder). + """ + margin = {"top": 45, "right": 160, "bottom": 55, "left": 70} + plot_w = width - margin["left"] - margin["right"] + plot_h = height - margin["top"] - margin["bottom"] + + # Resolve CI field names based on y_field + if y_field == "per_round_ler": + ci_lo_field, ci_hi_field = "per_round_ci_low", "per_round_ci_high" + else: + ci_lo_field, ci_hi_field = "ci_low", "ci_high" + + def _y(pt: dict) -> float: + v = pt.get(y_field) + return v if v is not None and v > 0 else 0.0 + + # Collect all p and y values for axis scaling + all_p = [] + all_ler = [] + for curve in curves: + for pt in curve["points"]: + all_p.append(pt["physical_error_rate"]) + yv = _y(pt) + if yv > 0: + all_ler.append(yv) + + if not all_p or not all_ler: + return f'No data' + + p_vals_pos = [p for p in all_p if p > 0] + p_min = min(p_vals_pos) if p_vals_pos else 1e-4 + p_max = max(p_vals_pos) if p_vals_pos else 1.0 + ler_min = max(1e-5, min(all_ler) * 0.5) + ler_max = min(1.0, max(all_ler) * 2.0) + + # Log scale for both axes + log_p_min = math.log10(p_min * 0.8) + log_p_max = math.log10(p_max * 1.2) + log_ler_min = math.log10(ler_min) + log_ler_max = math.log10(ler_max) + + def x_of(p: float) -> float: + if p <= 0: + return margin["left"] + log_p = math.log10(p) + frac = (log_p - log_p_min) / (log_p_max - log_p_min) if log_p_max != log_p_min else 0.5 + return margin["left"] + frac * plot_w + + def y_of(ler: float) -> float: + if ler <= 0: + return margin["top"] + plot_h + log_val = math.log10(ler) + frac = (log_val - log_ler_min) / (log_ler_max - log_ler_min) if log_ler_max != log_ler_min else 0.5 + return margin["top"] + (1 - frac) * plot_h + + parts = [ + f'', + # Background + f'', + # Title + f'{html_mod.escape(title)}', + ] + + # Grid lines (horizontal, log scale for y) + for exp in range(math.floor(log_ler_min), math.ceil(log_ler_max) + 1): + y = y_of(10**exp) + if margin["top"] <= y <= margin["top"] + plot_h: + parts.append( + f'', + ) + parts.append( + f'1e{exp}', + ) + + # Grid lines (vertical, log scale for x) + for exp in range(math.floor(log_p_min), math.ceil(log_p_max) + 1): + x = x_of(10**exp) + if margin["left"] <= x <= margin["left"] + plot_w: + parts.append( + f'', + ) + + # Axis labels + parts.append( + f'Physical error rate (p)', + ) + parts.append( + f'{html_mod.escape(y_label)}', + ) + + # X-axis tick labels (log-spaced) + # Show ticks at 1, 2, 5 * 10^n (standard log-scale subdivisions) + x_ticks = set() + for exp in range(int(math.floor(log_p_min)) - 1, int(math.ceil(log_p_max)) + 1): + for mult in [1.0, 2.0, 5.0]: + x_ticks.add(mult * 10.0**exp) + # Filter to visible range and limit density + visible_ticks = sorted(p for p in x_ticks if p > 0 and log_p_min <= math.log10(p) <= log_p_max) + # If too many ticks, keep only powers of 10 + if len(visible_ticks) > 8: + visible_ticks = sorted(p for p in visible_ticks if p == 10.0 ** round(math.log10(p))) + for p in visible_ticks: + x = x_of(p) + parts.append( + f'{_sci(p)}', + ) + + # Plot area border + parts.append( + f'', + ) + + # Threshold vertical line + if threshold_p is not None and p_min <= threshold_p <= p_max: + tx = x_of(threshold_p) + parts.append( + f'', + ) + parts.append( + f'p_th~{_sci(threshold_p)}', + ) + + # Draw curves + decoder_names = list(dict.fromkeys(c["decoder"] for c in curves)) + distances = sorted({c["distance"] for c in curves}) + + legend_y = margin["top"] + 10 + for curve in sorted(curves, key=lambda c: (decoder_names.index(c["decoder"]), c["distance"])): + dec_idx = decoder_names.index(curve["decoder"]) + dist_idx = distances.index(curve["distance"]) + if color_by == "distance": + color = (distance_color_map or {}).get(curve["distance"], _COLORS[dist_idx % len(_COLORS)]) + dash = _DASH_PATTERNS[dec_idx % len(_DASH_PATTERNS)] + else: + color = (decoder_color_map or {}).get(curve["decoder"], _COLORS[dec_idx % len(_COLORS)]) + dash = _DASH_PATTERNS[dist_idx % len(_DASH_PATTERNS)] + + # CI shaded band (draw first so it's behind everything) + band_upper = [] + band_lower = [] + for pt in curve["points"]: + yv = _y(pt) + if yv <= 0: + continue + ci_lo = pt.get(ci_lo_field) or 0 + ci_hi = pt.get(ci_hi_field) or 0 + if ci_lo > 0 and ci_hi > 0: + x = x_of(pt["physical_error_rate"]) + band_upper.append((x, y_of(ci_hi))) + band_lower.append((x, y_of(ci_lo))) + + if len(band_upper) >= 2: + band_d = " ".join(f"{'M' if i == 0 else 'L'}{x:.1f},{y:.1f}" for i, (x, y) in enumerate(band_upper)) + for x, y in reversed(band_lower): + band_d += f" L{x:.1f},{y:.1f}" + band_d += " Z" + parts.append( + f'', + ) + + # Center line + pts = [(x_of(pt["physical_error_rate"]), y_of(_y(pt))) for pt in curve["points"] if _y(pt) > 0] + + if len(pts) >= 2: + path_d = " ".join(f"{'M' if i == 0 else 'L'}{x:.1f},{y:.1f}" for i, (x, y) in enumerate(pts)) + dash_attr = f' stroke-dasharray="{dash}"' if dash else "" + parts.append( + f'', + ) + + # Data points with CI whiskers + for pt in curve["points"]: + yv = _y(pt) + if yv <= 0: + continue + x = x_of(pt["physical_error_rate"]) + y = y_of(yv) + parts.append(f'') + # CI whiskers + ci_lo = pt.get(ci_lo_field) or 0 + ci_hi = pt.get(ci_hi_field) or 0 + if ci_lo > 0 and ci_hi > 0: + y_lo = y_of(ci_lo) + y_hi = y_of(ci_hi) + parts.append( + f'', + ) + + # Legend entry + label = f"{curve['decoder']} d={curve['distance']}" + lx = margin["left"] + plot_w + 12 + dash_attr = f' stroke-dasharray="{dash}"' if dash else "" + parts.append( + f'', + ) + parts.append( + f'{html_mod.escape(label)}', + ) + legend_y += 16 + + parts.append("") + return "\n".join(parts) + + +def _build_duration_svg( + curves: list[dict], + title: str, + width: int = 560, + height: int = 380, +) -> str: + """Build an inline SVG of LER vs rounds for multiple (decoder, distance) curves at fixed p.""" + margin = {"top": 45, "right": 160, "bottom": 55, "left": 70} + plot_w = width - margin["left"] - margin["right"] + plot_h = height - margin["top"] - margin["bottom"] + + all_r = [] + all_ler = [] + for curve in curves: + for pt in curve["points"]: + all_r.append(pt["num_rounds"]) + if pt["logical_error_rate"] > 0: + all_ler.append(pt["logical_error_rate"]) + + if not all_r or not all_ler: + return f'No data' + + r_min, r_max = min(all_r), max(all_r) + ler_min = max(1e-5, min(all_ler) * 0.5) + ler_max = min(1.0, max(all_ler) * 2.0) + log_ler_min = math.log10(ler_min) + log_ler_max = math.log10(ler_max) + + def x_of(r: float) -> float: + if r_max == r_min: + return margin["left"] + plot_w / 2 + return margin["left"] + (r - r_min) / (r_max - r_min) * plot_w + + def y_of(ler: float) -> float: + if ler <= 0: + return margin["top"] + plot_h + log_val = math.log10(ler) + frac = (log_val - log_ler_min) / (log_ler_max - log_ler_min) if log_ler_max != log_ler_min else 0.5 + return margin["top"] + (1 - frac) * plot_h + + parts = [ + f'', + f'', + f'{html_mod.escape(title)}', + ] + + # Grid + axis labels + for exp in range(math.floor(log_ler_min), math.ceil(log_ler_max) + 1): + y = y_of(10**exp) + if margin["top"] <= y <= margin["top"] + plot_h: + parts.append( + f'', + ) + parts.append( + f'1e{exp}', + ) + + parts.append( + f'Rounds', + ) + parts.append( + f'Logical error rate', + ) + + for r in sorted(set(all_r)): + x = x_of(r) + parts.append( + f'{r}', + ) + + parts.append( + f'', + ) + + # Draw curves + legend_y = margin["top"] + 10 + for curve_idx, curve in enumerate(curves): + color = _COLORS[curve_idx % len(_COLORS)] + dash = _DASH_PATTERNS[curve_idx // len(_COLORS) % len(_DASH_PATTERNS)] + + pts = [ + (x_of(pt["num_rounds"]), y_of(pt["logical_error_rate"])) + for pt in curve["points"] + if pt["logical_error_rate"] > 0 + ] + + if len(pts) >= 2: + path_d = " ".join(f"{'M' if i == 0 else 'L'}{x:.1f},{y:.1f}" for i, (x, y) in enumerate(pts)) + dash_attr = f' stroke-dasharray="{dash}"' if dash else "" + parts.append( + f'', + ) + + for pt in curve["points"]: + if pt["logical_error_rate"] <= 0: + continue + x = x_of(pt["num_rounds"]) + y = y_of(pt["logical_error_rate"]) + parts.append(f'') + if pt["ci_low"] > 0 and pt["ci_high"] > 0: + y_lo = y_of(pt["ci_low"]) + y_hi = y_of(pt["ci_high"]) + parts.append( + f'', + ) + + label = f"{curve['decoder']} d={curve['distance']}" + lx = margin["left"] + plot_w + 12 + dash_attr = f' stroke-dasharray="{dash}"' if dash else "" + parts.append( + f'', + ) + parts.append( + f'{html_mod.escape(label)}', + ) + legend_y += 16 + + parts.append("") + return "\n".join(parts) + + +def _build_timing_svg( + tables: list[dict], + title: str, + width: int = 700, + height: int = 400, +) -> str: + """Build a violin plot SVG showing decode time distributions per decoder. + + Uses quantile data from DecodeStats (21 percentiles at 0%, 5%, ..., 100%) + to draw symmetric violins on a log-scale horizontal axis. + Falls back to box-style whiskers if quantiles are unavailable. + """ + margin = {"top": 45, "right": 30, "bottom": 55, "left": 120} + plot_w = width - margin["left"] - margin["right"] + plot_h = height - margin["top"] - margin["bottom"] + + # Collect all quantile arrays per decoder (one per operating point). + # We'll merge by taking the element-wise geometric mean. + decoder_quantiles: dict[str, list[list[float]]] = {} + for table in tables: + for row in table["rows"]: + dec = row["decoder"] + q = row.get("quantiles", []) + if q and any(v > 0 for v in q): + decoder_quantiles.setdefault(dec, []).append(q) + + # Fallback: synthesize quantiles from summary stats + if not decoder_quantiles: + for table in tables: + for row in table["rows"]: + dec = row["decoder"] + med = row["per_shot_median"] + p99 = row["per_shot_p99"] + mx = row["per_shot_max"] + if med > 0: + q = [med * 0.5] + [med] * 9 + [med] + [med] * 5 + [p99] * 3 + [mx, mx] + decoder_quantiles.setdefault(dec, []).append(q) + + if not decoder_quantiles: + return "" + + # Merge quantiles per decoder: geometric mean of each percentile position + merged: dict[str, list[float]] = {} + for dec, q_list in sorted(decoder_quantiles.items()): + n_q = len(q_list[0]) + result = [] + for i in range(n_q): + vals = [q[i] for q in q_list if i < len(q) and q[i] > 0] + if vals: + geo_mean = math.exp(sum(math.log(v) for v in vals) / len(vals)) + result.append(geo_mean) + else: + result.append(0.0) + merged[dec] = result + + decoders = list(merged.keys()) + all_vals = [v for qs in merged.values() for v in qs if v > 0] + if not all_vals: + return "" + + val_min = min(all_vals) * 0.3 + val_max = max(all_vals) * 3.0 + log_min = math.log10(val_min) + log_max = math.log10(val_max) + + def x_of(v: float) -> float: + if v <= 0: + return margin["left"] + frac = (math.log10(v) - log_min) / (log_max - log_min) if log_max != log_min else 0.5 + return margin["left"] + frac * plot_w + + violin_h = min(60, plot_h / len(decoders) * 0.75) + group_h = plot_h / len(decoders) + + parts = [ + f'', + f'', + f'{html_mod.escape(title)}', + ] + + # Grid lines (log scale) + for exp in range(math.floor(log_min), math.ceil(log_max) + 1): + x = x_of(10**exp) + if margin["left"] <= x <= margin["left"] + plot_w: + parts.append( + f'', + ) + parts.append( + f'1e{exp}s', + ) + + parts.append( + f'Decode time per shot (seconds, log scale)', + ) + + # Draw violins + for di, dec in enumerate(decoders): + qs = merged[dec] + cy = margin["top"] + di * group_h + group_h / 2 + color = _COLORS[di % len(_COLORS)] + + # Decoder label + parts.append( + f'{html_mod.escape(dec)}', + ) + + # Build violin shape from quantiles. + # The "width" at each quantile represents density: wider near the median, + # narrower at tails. We use a triangular kernel approximation where + # density ~ 1 / (gap between adjacent quantiles in log space). + n = len(qs) + if n < 3: + continue + + # Compute density proxy at each quantile + log_qs = [math.log10(max(v, 1e-12)) for v in qs] + densities = [] + for i in range(n): + left = log_qs[i] - log_qs[max(0, i - 1)] + right = log_qs[min(n - 1, i + 1)] - log_qs[i] + gap = left + right + densities.append(1.0 / max(gap, 0.01)) + + max_density = max(densities) if densities else 1.0 + half_h = violin_h / 2 + + # Build SVG path: top half then bottom half (mirror) + top_points = [] + bot_points = [] + for i in range(n): + if qs[i] <= 0: + continue + x = x_of(qs[i]) + dy = (densities[i] / max_density) * half_h + top_points.append((x, cy - dy)) + bot_points.append((x, cy + dy)) + + if len(top_points) < 2: + continue + + # Build path: top left-to-right, then bottom right-to-left + path_parts = [f"M{top_points[0][0]:.1f},{top_points[0][1]:.1f}"] + for x, y in top_points[1:]: + path_parts.append(f"L{x:.1f},{y:.1f}") + for x, y in reversed(bot_points): + path_parts.append(f"L{x:.1f},{y:.1f}") + path_parts.append("Z") + + parts.append( + f'', + ) + + # Median line + med_idx = n // 2 + if qs[med_idx] > 0: + mx = x_of(qs[med_idx]) + dy = (densities[med_idx] / max_density) * half_h + parts.append( + f'', + ) + parts.append( + f'' + f"{qs[med_idx]:.1e}s", + ) + + # p99 marker (index 19 of 21 = 95th percentile is close, use index ~20*0.99=19.8) + p99_idx = min(n - 2, int(n * 0.99)) + if p99_idx < n and qs[p99_idx] > 0: + px = x_of(qs[p99_idx]) + parts.append( + f'', + ) + + parts.append("") + return "\n".join(parts) + + +# -- HTML report -------------------------------------------------------------- + + +def _shots_summary(tables: list[dict]) -> str: + """Summarise shot counts across all comparison table rows.""" + all_counts = set() + for table in tables: + for row in table["rows"]: + all_counts.add(row["num_shots"]) + if not all_counts: + return "N/A" + lo, hi = min(all_counts), max(all_counts) + if lo == hi: + return str(lo) + return f"{lo} -- {hi} per point" + + +def _rounds_summary(tables: list[dict]) -> str: + """Summarise round counts per distance, e.g. 'd=3: r=[6,7,9]; d=5: r=[10,12,15]'.""" + from collections import defaultdict + + rounds_by_d: dict[int, set[int]] = defaultdict(set) + for table in tables: + rounds_by_d[table["distance"]].add(table["num_rounds"]) + if not rounds_by_d: + return "N/A" + lines = [] + for d in sorted(rounds_by_d): + rs = sorted(rounds_by_d[d]) + lines.append(html_mod.escape(f"d={d}: r=[{', '.join(str(r) for r in rs)}]")) + return "
".join(lines) + + +def _build_html(analysis: dict) -> str: + """Build the full HTML report string.""" + config = analysis.get("config", {}) + tables = analysis.get("comparison_tables", []) + curves = analysis.get("threshold_curves", []) + + style = dedent(""" + :root { + color-scheme: light dark; + --bg: #f8fafc; --fg: #0f172a; + --hero-bg: linear-gradient(135deg, #e0f2fe, #f8fafc 55%, #dcfce7); + --card-bg: white; --card-border: #dbeafe; --card-shadow: rgba(15,23,42,0.05); + --meta-bg: rgba(255,255,255,0.82); + --muted: #475569; --link: #2563eb; + --table-stripe: #f1f5f9; --table-border: #e2e8f0; + } + [data-theme="dark"] { + --bg: #0f172a; --fg: #e2e8f0; + --hero-bg: linear-gradient(135deg, #1e293b, #0f172a 55%, #1a2e1a); + --card-bg: #1e293b; --card-border: #334155; --card-shadow: rgba(0,0,0,0.3); + --meta-bg: rgba(30,41,59,0.82); + --muted: #94a3b8; --link: #60a5fa; + --table-stripe: #0f172a; --table-border: #334155; + } + @media (prefers-color-scheme: dark) { + :root:not([data-theme="light"]) { + --bg: #0f172a; --fg: #e2e8f0; + --hero-bg: linear-gradient(135deg, #1e293b, #0f172a 55%, #1a2e1a); + --card-bg: #1e293b; --card-border: #334155; --card-shadow: rgba(0,0,0,0.3); + --meta-bg: rgba(30,41,59,0.82); + --muted: #94a3b8; --link: #60a5fa; + --table-stripe: #0f172a; --table-border: #334155; + } + } + body { + margin: 0; + font-family: ui-sans-serif, -apple-system, BlinkMacSystemFont, sans-serif; + background: var(--bg); color: var(--fg); + } + main { max-width: 1400px; margin: 0 auto; padding: 32px 24px 56px; } + h1, h2, h3, p { margin-top: 0; } + .theme-toggle { + position: fixed; top: 16px; right: 16px; z-index: 100; + background: var(--card-bg); border: 1px solid var(--card-border); + border-radius: 8px; padding: 6px 12px; cursor: pointer; + color: var(--fg); font-size: 0.85rem; font-weight: 600; + } + .theme-toggle:hover { opacity: 0.8; } + .hero { + background: var(--hero-bg); + border: 1px solid var(--card-border); + border-radius: 20px; + padding: 24px; + margin-bottom: 24px; + } + .meta { + display: grid; + grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); + gap: 12px; + margin-top: 18px; + } + .meta-card { + background: var(--meta-bg); + border: 1px solid var(--card-border); + border-radius: 14px; + padding: 14px 16px; + } + .meta-card strong { + display: block; font-size: 0.82rem; text-transform: uppercase; + letter-spacing: 0.04em; color: var(--muted); margin-bottom: 6px; + } + .section { + background: var(--card-bg); + border: 1px solid var(--card-border); + border-radius: 18px; + padding: 20px 22px; + margin-top: 20px; + box-shadow: 0 10px 24px var(--card-shadow); + overflow-x: auto; + } + .plots { + display: flex; + flex-wrap: wrap; + gap: 16px; + justify-content: center; + } + table { border-collapse: collapse; width: 100%; margin: 12px 0 0; } + th, td { padding: 10px 14px; text-align: right; border-bottom: 1px solid var(--table-border); } + th { + font-size: 0.82rem; text-transform: uppercase; + letter-spacing: 0.03em; color: var(--muted); border-bottom-width: 2px; + } + td:first-child, th:first-child { text-align: left; } + tr:nth-child(even) td { background: var(--table-stripe); } + code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; } + details.collapsible { margin-top: 20px; } + details.collapsible > summary { + cursor: pointer; font-size: 1.1rem; font-weight: 600; + padding: 14px 22px; + background: var(--card-bg); border: 1px solid var(--card-border); + border-radius: 18px; + box-shadow: 0 10px 24px var(--card-shadow); + list-style: none; + } + details.collapsible > summary::before { content: "\\25B6 "; font-size: 0.8em; } + details.collapsible[open] > summary::before { content: "\\25BC "; } + details.collapsible > .section { margin-top: 8px; } + """).strip() + + def meta_card(label: str, value: str, *, raw: bool = False) -> str: + val = value if raw else html_mod.escape(value) + return f'
{html_mod.escape(label)}{val}
' + + decoders = config.get("decoders", []) + p1s = config.get("p1_scale", 1 / 30) + pms = config.get("p_meas_scale", 1 / 3) + pps = config.get("p_prep_scale", 1 / 3) + noise_str = f"Depolarizing: p1={p1s:.4g}*p, p2=p, p_meas={pms:.4g}*p, p_prep={pps:.4g}*p" + + # Build global color maps for consistency across all plots + all_decoders_sorted = sorted({c["decoder"] for c in curves}) if curves else decoders + all_distances_sorted = sorted({c["distance"] for c in curves}) if curves else [] + dec_colors = {d: _COLORS[i % len(_COLORS)] for i, d in enumerate(all_decoders_sorted)} + dist_colors = {d: _COLORS[i % len(_COLORS)] for i, d in enumerate(all_distances_sorted)} + + parts = [ + "", + '', + "", + ' ', + ' ', + " PECOS Decoder Performance Report", + f" ", + "", + "", + '', + "
", + '
', + "

PECOS Decoder Performance Report

", + "

Same samples decoded by multiple decoders. LER differences reflect " + "decoder quality, not sampling noise.

", + '
', + meta_card("Decoders", ", ".join(decoders)), + meta_card("Distances", ", ".join(str(d) for d in config.get("distances", []))), + meta_card("Basis", config.get("basis", "Z")), + meta_card("Shots", _shots_summary(tables)), + meta_card("Noise Model", noise_str), + meta_card("Error Rates (p)", ", ".join(f"{p:.4g}" for p in config.get("error_rates", []))), + "
", + '
', + meta_card("Rounds", _rounds_summary(tables), raw=True), + "
", + "
", + ] + + # -- Threshold curves section -- + if curves: + # Group curves by distance and by decoder + curves_by_distance: dict[int, list[dict]] = defaultdict(list) + curves_by_decoder: dict[str, list[dict]] = defaultdict(list) + for curve in curves: + curves_by_distance[curve["distance"]].append(curve) + curves_by_decoder[curve["decoder"]].append(curve) + + threshold_estimates = analysis.get("threshold_estimates", []) + fss_per_round_est = {e["decoder"]: e for e in threshold_estimates if e.get("metric") == "fss_per_round"} + fss_d_round_est = {e["decoder"]: e for e in threshold_estimates if e.get("metric") == "fss_d_round"} + + def _threshold_table(estimates: dict) -> list[str]: + if not estimates: + return [] + lines = [] + lines.append(" ") + lines.append( + " ", + ) + for est in sorted(estimates.values(), key=lambda e: e.get("estimated_p_th", 0), reverse=True): + p_th = est["estimated_p_th"] + se = est.get("std_error") + if se: + th_str = f"{_sci(p_th)} +/- {_sci(se)}" + else: + th_str = f"{_sci(p_th)}" + lines.append( + f" " + f"" + f"", + ) + lines.append("
DecoderThreshold (FSS fit)Distances
{html_mod.escape(est['decoder'])}{th_str}d={est['d_small']} -- d={est['d_large']}
") + return lines + + # === ALWAYS VISIBLE: Per-round LER === + + # Per-round by distance + parts.append('
') + parts.append("

Per-Round Logical Error Rate -- by Distance

") + parts.append( + "

All decoders compared at each distance. " + "Fitted from multiple syndrome extraction rounds per point.

", + ) + parts.append('
') + for d in sorted(curves_by_distance): + svg = _build_threshold_svg( + curves_by_distance[d], + title=f"d = {d}", + y_field="per_round_ler", + y_label="LER per round", + decoder_color_map=dec_colors, + ) + parts.append(f" {svg}") + parts.append("
") + parts.append("
") + + # Per-round by decoder (threshold view) + parts.append('
') + parts.append("

Per-Round Logical Error Rate -- by Decoder

") + parts.append( + "

Distance scaling for each decoder. " + "Curves crossing = threshold (per-round LER is distance-independent at threshold).

", + ) + parts.extend(_threshold_table(fss_per_round_est)) + parts.append('
') + for dec in sorted(curves_by_decoder): + est = fss_per_round_est.get(dec) + title = dec + p_th = None + if est: + p_th = est["estimated_p_th"] + title = f"{dec} (p_th ~ {p_th:.4f})" + svg = _build_threshold_svg( + curves_by_decoder[dec], + title=title, + color_by="distance", + threshold_p=p_th, + y_field="per_round_ler", + y_label="LER per round", + distance_color_map=dist_colors, + ) + parts.append(f" {svg}") + parts.append("
") + parts.append("
") + + # === COLLAPSIBLE: d-round LER === + parts.append('
') + parts.append(" d-Round Logical Error Rate (click to expand)") + + # d-round by distance + parts.append('
') + parts.append("

d-Round LER -- by Distance

") + parts.append("

Logical error rate over d rounds of syndrome extraction.

") + parts.append('
') + for d in sorted(curves_by_distance): + svg = _build_threshold_svg( + curves_by_distance[d], + title=f"d = {d}", + y_label="LER (d rounds)", + decoder_color_map=dec_colors, + ) + parts.append(f" {svg}") + parts.append("
") + parts.append("
") + + # d-round by decoder + parts.append('
') + parts.append("

d-Round LER -- by Decoder

") + parts.extend(_threshold_table(fss_d_round_est)) + parts.append('
') + for dec in sorted(curves_by_decoder): + est = fss_d_round_est.get(dec) + title = dec + p_th = None + if est: + p_th = est["estimated_p_th"] + title = f"{dec} (p_th ~ {p_th:.4f})" + svg = _build_threshold_svg( + curves_by_decoder[dec], + title=title, + color_by="distance", + threshold_p=p_th, + y_label="LER (d rounds)", + distance_color_map=dist_colors, + ) + parts.append(f" {svg}") + parts.append("
") + parts.append("
") + parts.append("
") + + # -- Duration curves (collapsible) -- + duration_curves = analysis.get("duration_curves", []) + if duration_curves: + # Group by physical_error_rate + dur_by_p: dict[float, list[dict]] = defaultdict(list) + for dc in duration_curves: + dur_by_p[dc["physical_error_rate"]].append(dc) + + parts.append('
') + parts.append(" Duration Curves -- LER vs Rounds (click to expand)") + parts.append('
') + parts.append( + "

Logical error rate vs number of rounds at fixed physical error rate. " + "Shows how LER grows with memory duration.

", + ) + parts.append('
') + for p in sorted(dur_by_p): + svg = _build_duration_svg(dur_by_p[p], title=f"p = {p:.4g}") + parts.append(f" {svg}") + parts.append("
") + parts.append("
") + parts.append("
") + + # -- Timing comparison section -- + if tables: + err_rates = sorted({t["physical_error_rate"] for t in tables}) + distances_available = sorted({t["distance"] for t in tables}) + + def _violin_plots_for_p(p_val: float) -> list[str]: + """Generate violin SVGs for each distance at a given error rate.""" + svgs = [] + for d in distances_available: + candidates = [t for t in tables if t["distance"] == d and t["physical_error_rate"] == p_val] + if not candidates: + continue + target_r = 2 * d + best = min(candidates, key=lambda t: abs(t["num_rounds"] - target_r)) + svg = _build_timing_svg( + [best], + title=f"d = {d}, r = {best['num_rounds']}", + ) + svgs.append(svg) + return svgs + + # Always-visible: lowest error rate + if err_rates: + lowest_p = err_rates[0] + svgs = _violin_plots_for_p(lowest_p) + if svgs: + parts.append('
') + parts.append(f"

Decode Speed (p = {lowest_p:.4g})

") + parts.append("

Per-shot decode time distribution for each decoder and distance.

") + parts.append('
') + parts.extend(f" {svg}" for svg in svgs) + parts.append("
") + parts.append("
") + + # Collapsible: all other error rates + other_rates = [p for p in err_rates if p != err_rates[0]] + if other_rates: + parts.append('
') + parts.append(" Decode Speed at Other Error Rates (click to expand)") + for p_val in other_rates: + svgs = _violin_plots_for_p(p_val) + if svgs: + parts.append('
') + parts.append(f"

p = {p_val:.4g}

") + parts.append('
') + parts.extend(f" {svg}" for svg in svgs) + parts.append("
") + parts.append("
") + parts.append("
") + + # -- Comparison tables (collapsible) -- + if tables: + parts.append('
') + parts.append(" Detailed Comparison Tables (click to expand)") + for table in tables: + d = table["distance"] + p = table["physical_error_rate"] + r = table["num_rounds"] + n = table["num_shots"] + + parts.append('
') + parts.append(f"

d={d}, p={p:.4g}, rounds={r} ({n} shots)

") + parts.append(" ") + parts.append( + " " + "", + ) + + for row in table["rows"]: + ler_str = f"{row['logical_error_rate']:.4f} ({row['ci_low']:.4f} - {row['ci_high']:.4f})" + sps = row["num_shots"] / row["per_shot_median"] if row["per_shot_median"] > 0 else float("inf") + parts.append( + f" " + f"" + f"" + f"" + f"" + f"" + f"" + f"", + ) + + parts.append("
DecoderLER (95% CI)Medianp99MaxThroughput
{html_mod.escape(row['decoder'])}{ler_str}{row['per_shot_median']:.1e} s{row['per_shot_p99']:.1e} s{row['per_shot_max']:.1e} s{sps:.1e} shots/s
") + parts.append("
") + parts.append("
") + + parts.extend( + [ + "
", + dedent(""" + + """).strip(), + "", + "", + ], + ) + + return "\n".join(parts) + + +# -- PDF report (matplotlib) -------------------------------------------------- + + +def _build_pdf(analysis: dict, output_path: Path) -> None: + """Build a multi-page PDF report using matplotlib.""" + import matplotlib.pyplot as plt + from matplotlib.backends.backend_pdf import PdfPages + + config = analysis.get("config", {}) + tables = analysis.get("comparison_tables", []) + curves = analysis.get("threshold_curves", []) + + page_size = (11, 8.5) + + with PdfPages(output_path) as pdf: + # -- Cover page -- + fig, ax = plt.subplots(figsize=page_size) + ax.axis("off") + ax.text( + 0.5, + 0.65, + "PECOS Decoder Performance Report", + transform=ax.transAxes, + fontsize=24, + ha="center", + va="center", + fontweight="bold", + ) + + info_lines = [ + f"Decoders: {', '.join(config.get('decoders', []))}", + f"Distances: {config.get('distances', [])}", + f"Error rates: {config.get('error_rates', [])}", + f"Shots: {config.get('shots', 'N/A')}", + f"Basis: {config.get('basis', 'Z')}", + ] + ax.text( + 0.5, + 0.40, + "\n".join(info_lines), + transform=ax.transAxes, + fontsize=12, + ha="center", + va="center", + family="monospace", + ) + pdf.savefig(fig) + plt.close(fig) + + # -- Threshold curve plots -- + if curves: + curves_by_distance: dict[int, list[dict]] = defaultdict(list) + curves_by_decoder: dict[str, list[dict]] = defaultdict(list) + for curve in curves: + curves_by_distance[curve["distance"]].append(curve) + curves_by_decoder[curve["decoder"]].append(curve) + + def _plot_curves( + ax: plt.Axes, + curve_list: list[dict], + title: str, + color_by: str = "decoder", + ) -> None: + ax.set_title(title, fontsize=14, fontweight="bold") + ax.set_xlabel("Physical error rate (p)") + ax.set_ylabel("Logical error rate") + ax.set_yscale("log") + ax.grid(visible=True, alpha=0.3) + decoder_names = list(dict.fromkeys(c["decoder"] for c in curve_list)) + dists = sorted({c["distance"] for c in curve_list}) + linestyles = ["-", "--", ":", "-."] + for curve in sorted(curve_list, key=lambda c: (decoder_names.index(c["decoder"]), c["distance"])): + pts = [pt for pt in curve["points"] if pt["logical_error_rate"] > 0] + if not pts: + continue + ps = [pt["physical_error_rate"] for pt in pts] + lers = [pt["logical_error_rate"] for pt in pts] + ci_lows = [pt["ci_low"] for pt in pts] + ci_highs = [pt["ci_high"] for pt in pts] + dec_idx = decoder_names.index(curve["decoder"]) + dist_idx = dists.index(curve["distance"]) + if color_by == "distance": + color = _COLORS[dist_idx % len(_COLORS)] + ls = linestyles[dec_idx % len(linestyles)] + else: + color = _COLORS[dec_idx % len(_COLORS)] + ls = linestyles[dist_idx % len(linestyles)] + label = f"{curve['decoder']} d={curve['distance']}" + ax.plot(ps, lers, marker="o", linestyle=ls, color=color, label=label, markersize=4) + ax.fill_between(ps, ci_lows, ci_highs, color=color, alpha=0.15) + ax.legend(fontsize=9, loc="best") + + # Per-distance plots (all decoders) + for d in sorted(curves_by_distance): + fig, ax = plt.subplots(figsize=page_size) + _plot_curves(ax, curves_by_distance[d], f"By Distance -- d = {d}") + fig.tight_layout() + pdf.savefig(fig) + plt.close(fig) + + # Per-decoder plots (all distances -- color by distance, threshold line) + threshold_estimates = analysis.get("threshold_estimates", []) + est_by_dec = {e["decoder"]: e for e in threshold_estimates} + for dec in sorted(curves_by_decoder): + fig, ax = plt.subplots(figsize=page_size) + est = est_by_dec.get(dec) + title = f"By Decoder -- {dec}" + if est: + title += f" (p_th ~ {est['estimated_p_th']:.4f})" + _plot_curves(ax, curves_by_decoder[dec], title, color_by="distance") + if est: + ax.axvline( + est["estimated_p_th"], + color="#334155", + linestyle=":", + linewidth=1.8, + alpha=0.7, + zorder=0, + ) + fig.tight_layout() + pdf.savefig(fig) + plt.close(fig) + + # -- Duration curve plots -- + duration_curves = analysis.get("duration_curves", []) + if duration_curves: + dur_by_p: dict[float, list[dict]] = defaultdict(list) + for dc in duration_curves: + dur_by_p[dc["physical_error_rate"]].append(dc) + + for p_val in sorted(dur_by_p): + fig, ax = plt.subplots(figsize=page_size) + ax.set_title(f"Duration -- p = {p_val:.4g}", fontsize=14, fontweight="bold") + ax.set_xlabel("Rounds") + ax.set_ylabel("Logical error rate") + ax.set_yscale("log") + ax.grid(visible=True, alpha=0.3) + + for ci, dc in enumerate(dur_by_p[p_val]): + pts = [pt for pt in dc["points"] if pt["logical_error_rate"] > 0] + if not pts: + continue + rs = [pt["num_rounds"] for pt in pts] + lers = [pt["logical_error_rate"] for pt in pts] + ci_lows = [pt["ci_low"] for pt in pts] + ci_highs = [pt["ci_high"] for pt in pts] + color = _COLORS[ci % len(_COLORS)] + label = f"{dc['decoder']} d={dc['distance']}" + ax.plot(rs, lers, "o-", color=color, label=label, markersize=4) + ax.fill_between(rs, ci_lows, ci_highs, color=color, alpha=0.15) + + ax.legend(fontsize=9, loc="best") + fig.tight_layout() + pdf.savefig(fig) + plt.close(fig) + + # -- Comparison tables as figures -- + for table in tables: + fig, ax = plt.subplots(figsize=page_size) + ax.axis("off") + ax.set_title( + f"d={table['distance']}, p={table['physical_error_rate']:.4g}, " + f"rounds={table['num_rounds']} ({table['num_shots']} shots)", + fontsize=14, + fontweight="bold", + pad=20, + ) + + col_labels = ["Decoder", "LER", "95% CI", "Median", "p99", "Max"] + cell_data = [ + [ + row["decoder"], + f"{row['logical_error_rate']:.4f}", + f"{row['ci_low']:.4f} - {row['ci_high']:.4f}", + f"{row['per_shot_median']:.1e} s", + f"{row['per_shot_p99']:.1e} s", + f"{row['per_shot_max']:.1e} s", + ] + for row in table["rows"] + ] + + if cell_data: + tbl = ax.table( + cellText=cell_data, + colLabels=col_labels, + loc="center", + cellLoc="center", + ) + tbl.auto_set_font_size(value=False) + tbl.set_fontsize(10) + tbl.scale(1.0, 1.8) + + # Style header row + for j in range(len(col_labels)): + tbl[0, j].set_facecolor("#e2e8f0") + tbl[0, j].set_text_props(fontweight="bold") + + fig.tight_layout() + pdf.savefig(fig) + plt.close(fig) + + +# -- Markdown report (Obsidian-compatible) ------------------------------------ + + +def _build_markdown(analysis: dict, plots_dir: Path) -> str: + """Build an Obsidian-compatible Markdown report with standalone SVG plots.""" + config = analysis.get("config", {}) + tables = analysis.get("comparison_tables", []) + curves = analysis.get("threshold_curves", []) + + decoders = config.get("decoders", []) + p1s = config.get("p1_scale", 1 / 30) + pms = config.get("p_meas_scale", 1 / 3) + pps = config.get("p_prep_scale", 1 / 3) + noise_str = f"Depolarizing: p1={p1s:.4g}*p, p2=p, p_meas={pms:.4g}*p, p_prep={pps:.4g}*p" + + # Global color maps + all_decoders_sorted = sorted({c["decoder"] for c in curves}) if curves else decoders + all_distances_sorted = sorted({c["distance"] for c in curves}) if curves else [] + dec_colors = {d: _COLORS[i % len(_COLORS)] for i, d in enumerate(all_decoders_sorted)} + dist_colors = {d: _COLORS[i % len(_COLORS)] for i, d in enumerate(all_distances_sorted)} + + # Rounds summary + rounds_by_d: dict[int, set[int]] = defaultdict(set) + for table in tables: + rounds_by_d[table["distance"]].add(table["num_rounds"]) + + def _save_svg(svg_content: str, name: str) -> str: + """Save SVG to plots_dir and return relative path.""" + filename = f"{name}.svg" + (plots_dir / filename).write_text(svg_content) + return f"plots/{filename}" + + lines = [] + + # -- Frontmatter -- + lines.append("---") + lines.append("title: PECOS Decoder Performance Report") + lines.append("tags: [report, surface-code, decoders]") + lines.append(f"decoders: [{', '.join(decoders)}]") + lines.append(f"distances: [{', '.join(str(d) for d in config.get('distances', []))}]") + lines.append(f"date: {__import__('datetime').date.today().isoformat()}") + lines.append("---") + lines.append("") + + # -- Header -- + lines.append("# PECOS Decoder Performance Report") + lines.append("") + lines.append("> [!info] Configuration") + lines.append(f"> **Decoders:** {', '.join(decoders)}") + lines.append(f"> **Distances:** {', '.join(str(d) for d in config.get('distances', []))}") + lines.append(f"> **Error Rates (p):** {', '.join(f'{p:.4g}' for p in config.get('error_rates', []))}") + lines.append(f"> **Shots:** {_shots_summary(tables)}") + lines.append(f"> **Noise Model:** {noise_str}") + lines.append(f"> **Basis:** {config.get('basis', 'Z')}") + for d in sorted(rounds_by_d): + rs = sorted(rounds_by_d[d]) + lines.append(f"> **d={d}:** r=[{', '.join(str(r) for r in rs)}]") + lines.append("") + + if curves: + curves_by_distance: dict[int, list[dict]] = defaultdict(list) + curves_by_decoder: dict[str, list[dict]] = defaultdict(list) + for curve in curves: + curves_by_distance[curve["distance"]].append(curve) + curves_by_decoder[curve["decoder"]].append(curve) + + threshold_estimates = analysis.get("threshold_estimates", []) + fss_per_round_est = {e["decoder"]: e for e in threshold_estimates if e.get("metric") == "fss_per_round"} + fss_d_round_est = {e["decoder"]: e for e in threshold_estimates if e.get("metric") == "fss_d_round"} + + # -- Per-round by distance -- + lines.append("## Per-Round LER -- by Distance") + lines.append("") + for d in sorted(curves_by_distance): + svg = _build_threshold_svg( + curves_by_distance[d], + title=f"d = {d}", + y_field="per_round_ler", + y_label="LER per round", + decoder_color_map=dec_colors, + ) + path = _save_svg(svg, f"per_round_by_dist_d{d}") + lines.append(f"![d={d}]({path})") + lines.append("") + + # -- Per-round by decoder with thresholds -- + lines.append("## Per-Round LER -- by Decoder") + lines.append("") + + if fss_per_round_est: + lines.append("### Threshold Estimates (per-round)") + lines.append("") + lines.append("| Decoder | Threshold | Distances |") + lines.append("|---------|-----------|-----------|") + lines.extend( + f"| {est['decoder']} | {est['estimated_p_th']:.4f} " + f"| d={est['d_small']} / d={est['d_large']} crossing |" + for est in sorted(fss_per_round_est.values(), key=lambda e: e["estimated_p_th"], reverse=True) + ) + lines.append("") + + for dec in sorted(curves_by_decoder): + est = fss_per_round_est.get(dec) + title = dec + p_th = None + if est: + p_th = est["estimated_p_th"] + title = f"{dec} (p_th ~ {p_th:.4f})" + svg = _build_threshold_svg( + curves_by_decoder[dec], + title=title, + color_by="distance", + threshold_p=p_th, + y_field="per_round_ler", + y_label="LER per round", + distance_color_map=dist_colors, + ) + path = _save_svg(svg, f"per_round_by_dec_{dec.replace(':', '_')}") + lines.append(f"![{dec}]({path})") + lines.append("") + + # -- d-round LER (collapsible) -- + lines.append("> [!note]- d-Round Logical Error Rate (click to expand)") + lines.append(">") + lines.append("> ### d-Round LER -- by Distance") + lines.append(">") + for d in sorted(curves_by_distance): + svg = _build_threshold_svg( + curves_by_distance[d], + title=f"d = {d}", + y_label="LER (d rounds)", + decoder_color_map=dec_colors, + ) + path = _save_svg(svg, f"d_round_by_dist_d{d}") + lines.append(f"> ![d={d}]({path})") + lines.append(">") + + if fss_d_round_est: + lines.append("> ### Threshold Estimates (d-round)") + lines.append(">") + lines.append("> | Decoder | Threshold | Distances |") + lines.append("> |---------|-----------|-----------|") + lines.extend( + f"> | {est['decoder']} | {est['estimated_p_th']:.4f} " + f"| d={est['d_small']} / d={est['d_large']} crossing |" + for est in sorted(fss_d_round_est.values(), key=lambda e: e["estimated_p_th"], reverse=True) + ) + lines.append(">") + + for dec in sorted(curves_by_decoder): + est = fss_d_round_est.get(dec) + title = dec + p_th = None + if est: + p_th = est["estimated_p_th"] + title = f"{dec} (p_th ~ {p_th:.4f})" + svg = _build_threshold_svg( + curves_by_decoder[dec], + title=title, + color_by="distance", + threshold_p=p_th, + y_label="LER (d rounds)", + distance_color_map=dist_colors, + ) + path = _save_svg(svg, f"d_round_by_dec_{dec.replace(':', '_')}") + lines.append(f"> ![{dec}]({path})") + lines.append(">") + lines.append("") + + # -- Duration curves (collapsible) -- + duration_curves = analysis.get("duration_curves", []) + if duration_curves: + dur_by_p: dict[float, list[dict]] = defaultdict(list) + for dc in duration_curves: + dur_by_p[dc["physical_error_rate"]].append(dc) + + lines.append("> [!note]- Duration Curves -- LER vs Rounds (click to expand)") + lines.append(">") + for p in sorted(dur_by_p): + svg = _build_duration_svg(dur_by_p[p], title=f"p = {p:.4g}") + path = _save_svg(svg, f"duration_p{p:.4g}".replace(".", "_")) + lines.append(f"> ![p={p:.4g}]({path})") + lines.append(">") + lines.append("") + + # -- Decode speed -- + if tables: + err_rates = sorted({t["physical_error_rate"] for t in tables}) + distances_available = sorted({t["distance"] for t in tables}) + + if err_rates: + lowest_p = err_rates[0] + lines.append(f"## Decode Speed (p = {lowest_p:.4g})") + lines.append("") + for d in distances_available: + candidates = [t for t in tables if t["distance"] == d and t["physical_error_rate"] == lowest_p] + if not candidates: + continue + target_r = 2 * d + best = min(candidates, key=lambda t: abs(t["num_rounds"] - target_r)) + svg = _build_timing_svg([best], title=f"d = {d}, r = {best['num_rounds']}") + path = _save_svg(svg, f"timing_d{d}_p{lowest_p:.4g}".replace(".", "_")) + lines.append(f"![d={d}]({path})") + lines.append("") + + # Other error rates collapsible + other_rates = [p for p in err_rates if p != err_rates[0]] if err_rates else [] + if other_rates: + lines.append("> [!note]- Decode Speed at Other Error Rates (click to expand)") + lines.append(">") + for p_val in other_rates: + lines.append(f"> **p = {p_val:.4g}**") + lines.append(">") + for d in distances_available: + candidates = [t for t in tables if t["distance"] == d and t["physical_error_rate"] == p_val] + if not candidates: + continue + target_r = 2 * d + best = min(candidates, key=lambda t: abs(t["num_rounds"] - target_r)) + svg = _build_timing_svg([best], title=f"d = {d}, r = {best['num_rounds']}") + path = _save_svg(svg, f"timing_d{d}_p{p_val:.4g}".replace(".", "_")) + lines.append(f"> ![d={d}]({path})") + lines.append(">") + lines.append("") + + # -- Comparison tables (collapsible) -- + if tables: + lines.append("> [!note]- Detailed Comparison Tables (click to expand)") + lines.append(">") + for table in tables: + d = table["distance"] + p = table["physical_error_rate"] + r = table["num_rounds"] + n = table["num_shots"] + lines.append(f"> ### d={d}, p={p:.4g}, rounds={r} ({n} shots)") + lines.append(">") + lines.append("> | Decoder | LER (95% CI) | Median | p99 | Max | Throughput |") + lines.append("> |---------|-------------|--------|-----|-----|------------|") + for row in table["rows"]: + ler_str = f"{row['logical_error_rate']:.4f} ({row['ci_low']:.4f} - {row['ci_high']:.4f})" + sps = row["num_shots"] / row["per_shot_median"] if row["per_shot_median"] > 0 else float("inf") + lines.append( + f"> | {row['decoder']} | {ler_str} " + f"| {row['per_shot_median']:.1e} s " + f"| {row['per_shot_p99']:.1e} s " + f"| {row['per_shot_max']:.1e} s " + f"| {sps:.1e} shots/s |", + ) + lines.append(">") + lines.append("") + + return "\n".join(lines) + + +# -- CLI ---------------------------------------------------------------------- + + +def main() -> int: + """CLI entry point for report generation.""" + parser = argparse.ArgumentParser( + description=__doc__, + formatter_class=argparse.RawDescriptionHelpFormatter, + ) + parser.add_argument("analysis", type=Path, help="Analysis JSON from analyze_data.py") + parser.add_argument("--html", action="store_true", help="Generate HTML report") + parser.add_argument("--pdf", action="store_true", help="Generate PDF report (requires matplotlib)") + parser.add_argument("--markdown", action="store_true", help="Generate Obsidian-compatible Markdown report") + parser.add_argument("--open", action="store_true", help="Open HTML report in browser") + parser.add_argument("-o", "--output-dir", type=str, default=None) + args = parser.parse_args() + + if not args.html and not args.pdf and not args.markdown: + args.html = True # default to HTML + + analysis = _load_analysis(args.analysis) + + out = Path(args.output_dir) if args.output_dir else args.analysis.parent + out.mkdir(parents=True, exist_ok=True) + + if args.html: + html_path = out / "report.html" + html_path.write_text(_build_html(analysis)) + print(f"Wrote {html_path}") + + if args.open: + import webbrowser + + webbrowser.open(html_path.as_uri()) + print(f"Opened {html_path}") + + if args.pdf: + pdf_path = out / "report.pdf" + _build_pdf(analysis, pdf_path) + print(f"Wrote {pdf_path}") + + if args.markdown: + plots_dir = out / "plots" + plots_dir.mkdir(parents=True, exist_ok=True) + md_path = out / "report.md" + md_path.write_text(_build_markdown(analysis, plots_dir)) + n_plots = len(list(plots_dir.glob("*.svg"))) + print(f"Wrote {md_path} ({n_plots} SVG plots in {plots_dir}/)") + + return 0 + + +if __name__ == "__main__": + raise SystemExit(main()) diff --git a/examples/surface/coherent_noise_sweep.py b/examples/surface/coherent_noise_sweep.py new file mode 100644 index 000000000..06d15cec0 --- /dev/null +++ b/examples/surface/coherent_noise_sweep.py @@ -0,0 +1,316 @@ +r"""Coherent idle noise sweep: surface code memory with RZ phase accumulation. + +Studies the impact of coherent Z-phase noise (RZ rotation after each CX gate) +on surface code memory experiments. Uses sim_neo for Rust-native simulation +with composable noise model (depolarizing + coherent idle RZ). + +The coherent noise models uncompensated phase accumulation during idle time +between gates. Unlike stochastic Z errors (which scale as p_z per gate), +coherent RZ rotations accumulate constructively, causing error rates far +higher than the Pauli-twirled equivalent sin²(θ/2). + +Example: + uv run python examples/surface/coherent_noise_sweep.py \ + --distance 3 --rounds 3 --basis X \ + --p-depol 0.003 \ + --p-idle 0.0 0.01 0.03 0.05 0.07 0.1 \ + --shots 10000 --save-html --open +""" + +from __future__ import annotations + +import argparse +import json +import math +import sys +import time +from dataclasses import asdict, dataclass, field +from pathlib import Path + +sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "python" / "quantum-pecos" / "src")) + + +@dataclass +class CoherentNoisePoint: + p_idle: float + p_twirled: float + ler: float + errors: int + shots: int + standard_error: float + sim_seconds: float + decode_seconds: float + + +@dataclass +class CoherentNoiseSweep: + distance: int + rounds: int + basis: str + p_depol: float + backend: str + points: list[CoherentNoisePoint] = field(default_factory=list) + total_seconds: float = 0.0 + + +def run_sweep( + *, + distance: int, + rounds: int, + basis: str, + p_depol: float, + p_idle_values: list[float], + shots: int, + seed: int, + backend: str, + lazy_measure: bool, + max_bond_dim: int, +) -> CoherentNoiseSweep: + """Run a coherent noise sweep using sim_neo.""" + from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch + from pecos_rslib.qec import ObservableSubgraphDecoder + from pecos_rslib_exp import sim_neo, stab_mps, statevec, depolarizing + + patch = SurfacePatch.create(distance=distance) + b = LogicalCircuitBuilder() + b.add_patch(patch, "Q0") + b.add_memory("Q0", rounds=rounds, basis=basis) + tc = b.to_tick_circuit() + + det_json = json.loads(tc.get_meta("detectors")) + obs_json = json.loads(tc.get_meta("observables")) + num_meas = int(tc.get_meta("num_measurements")) + dem_str = b.build_dem(p1=p_depol, p2=p_depol, p_meas=p_depol, p_prep=p_depol) + sc = b.stab_coords() + osd = ObservableSubgraphDecoder(dem_str, sc, "pymatching") + + sweep = CoherentNoiseSweep( + distance=distance, + rounds=rounds, + basis=basis, + p_depol=p_depol, + backend=backend, + ) + t_total = time.perf_counter() + + for p_idle in p_idle_values: + # Simulate + t0 = time.perf_counter() + noise = (depolarizing() + .p1(p_depol).p2(p_depol) + .p_meas(p_depol).p_prep(p_depol) + .idle_rz(p_idle)) + builder = (sim_neo(tc) + .noise(noise) + .shots(shots) + .seed(seed)) + if backend == "stabmps": + builder = builder.quantum( + ( + stab_mps().lazy_measure().max_bond_dim(max_bond_dim) + if lazy_measure + else stab_mps().max_bond_dim(max_bond_dim) + ), + ) + else: + builder = builder.quantum(statevec()) + results = builder.run() + sim_time = time.perf_counter() - t0 + + # Decode + t0 = time.perf_counter() + errors = 0 + for r in results: + meas = list(r) + det_events = [] + for det in det_json: + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + det_events.append(val) + obs_mask = 0 + for obs in obs_json: + val = 0 + for rec in obs["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + obs_mask |= 1 << obs["id"] + pred = osd.decode([int(x) for x in det_events]) + if pred != obs_mask: + errors += 1 + decode_time = time.perf_counter() - t0 + + ler = errors / shots + se = math.sqrt(ler * (1 - ler) / shots) if shots > 0 else 0 + p_twirled = math.sin(p_idle / 2) ** 2 + + point = CoherentNoisePoint( + p_idle=p_idle, + p_twirled=p_twirled, + ler=ler, + errors=errors, + shots=shots, + standard_error=se, + sim_seconds=sim_time, + decode_seconds=decode_time, + ) + sweep.points.append(point) + print( + f" p_idle={p_idle:.3f} sin²(θ/2)={p_twirled:.5f} " + f"LER={ler:.4f} ± {se:.4f} ({errors}/{shots}) " + f"sim={sim_time:.1f}s decode={decode_time:.1f}s", + flush=True, + ) + + sweep.total_seconds = time.perf_counter() - t_total + return sweep + + +def write_html_report(sweep: CoherentNoiseSweep, path: Path) -> None: + """Write an HTML report from the sweep results.""" + html_parts = [ + "", + "Coherent Idle Noise Sweep", + "", + f"

Coherent Idle Noise: {sweep.basis}-basis Memory d={sweep.distance}

", + f"

Depolarizing: p={sweep.p_depol}, rounds={sweep.rounds}, " f"backend={sweep.backend}

", + f"

Total time: {sweep.total_seconds:.1f}s

", + "", + "
About Coherent Idle Noise", + '
', + "

After each two-qubit gate (CX), an RZ(θ) rotation is applied to both " + "qubits, modeling uncompensated phase accumulation during idle time. Unlike " + "stochastic Z errors, coherent rotations accumulate constructively across gates, " + "causing logical error rates far higher than the Pauli-twirled equivalent " + "sin²(θ/2).

", + "

The decoder uses a stochastic-only DEM (no knowledge of coherent noise). " + "The gap between the coherent LER and the twirled LER measures how much the " + "decoder is mismatched to the actual noise.

", + "
", + "", + "

Results

", + "", + "", + "", + "", + "", + "", + "", + "", + ] + + for pt in sweep.points: + cls = "good" if pt.ler < 0.05 else "bad" + html_parts.append( + f"" + f"" + f'' + f"" + f"" + f"", + ) + + html_parts.append("
θ (rad)sin²(θ/2)LER± SEErrorsShots
{pt.p_idle:.3f}{pt.p_twirled:.5f}{pt.ler:.4f}{pt.standard_error:.4f}{pt.errors}{pt.shots}
") + + # Amplification factor + if len(sweep.points) >= 2 and sweep.points[0].ler > 0: + baseline = sweep.points[0].ler + html_parts.append("

Coherent Amplification

") + html_parts.append("" "") + for pt in sweep.points[1:]: + ratio = pt.ler / baseline + twirl_ratio = pt.ler / pt.p_twirled if pt.p_twirled > 0 else 0 + html_parts.append( + f"" f"" f"", + ) + html_parts.append("
θLER / baselineLER / twirled
{pt.p_idle:.3f}{ratio:.1f}x{twirl_ratio:.0f}x
") + + html_parts.append("") + path.write_text("\n".join(html_parts)) + print(f"Report written to {path}") + + +def main(): + parser = argparse.ArgumentParser( + description=__doc__, + formatter_class=argparse.RawDescriptionHelpFormatter, + ) + parser.add_argument("--distance", "-d", type=int, default=3) + parser.add_argument("--rounds", type=int, default=None, help="Syndrome rounds (default: distance)") + parser.add_argument( + "--basis", choices=["X", "Z"], default="X", help="Memory basis (default: X, where RZ noise is visible)" + ) + parser.add_argument("--p-depol", type=float, default=0.003) + parser.add_argument("--p-idle", type=float, nargs="+", default=[0.0, 0.01, 0.02, 0.03, 0.05, 0.07, 0.1]) + parser.add_argument("--shots", type=int, default=10000) + parser.add_argument("--seed", type=int, default=42) + parser.add_argument("--backend", choices=["statevec", "stabmps"], default="statevec") + parser.add_argument("--lazy-measure", action="store_true", default=True) + parser.add_argument("--max-bond-dim", type=int, default=128) + parser.add_argument("--output-dir", type=Path, default=Path("/tmp/coherent_noise")) + parser.add_argument("--save-json", action="store_true") + parser.add_argument("--save-html", action="store_true") + parser.add_argument("--open", action="store_true") + args = parser.parse_args() + + if args.rounds is None: + args.rounds = args.distance + + print( + f"Coherent idle noise sweep: {args.basis}-basis memory d={args.distance}, " + f"rounds={args.rounds}, p_depol={args.p_depol}", + flush=True, + ) + print( + f"Backend: {args.backend}, shots={args.shots}, seed={args.seed}", + flush=True, + ) + print(flush=True) + + sweep = run_sweep( + distance=args.distance, + rounds=args.rounds, + basis=args.basis, + p_depol=args.p_depol, + p_idle_values=args.p_idle, + shots=args.shots, + seed=args.seed, + backend=args.backend, + lazy_measure=args.lazy_measure, + max_bond_dim=args.max_bond_dim, + ) + + print(f"\nTotal: {sweep.total_seconds:.1f}s", flush=True) + + args.output_dir.mkdir(parents=True, exist_ok=True) + + if args.save_json: + json_path = args.output_dir / "coherent_noise_results.json" + json_path.write_text(json.dumps(asdict(sweep), indent=2)) + print(f"JSON written to {json_path}") + + if args.save_html or args.open: + html_path = args.output_dir / "coherent_noise_report.html" + write_html_report(sweep, html_path) + if args.open: + import webbrowser + + webbrowser.open(str(html_path)) + + +if __name__ == "__main__": + main() diff --git a/examples/surface/d3_fault_catalog_lookup.rs b/examples/surface/d3_fault_catalog_lookup.rs new file mode 100644 index 000000000..2e6422d87 --- /dev/null +++ b/examples/surface/d3_fault_catalog_lookup.rs @@ -0,0 +1,597 @@ +// Copyright 2026 The PECOS Developers +// Licensed under the Apache License, Version 2.0 + +//! Build a truncated maximum-likelihood lookup table from the Rust fault catalog. +//! +//! This example keeps the expensive loop in Rust: +//! - build a d=3 rotated surface-code Z-memory experiment, +//! - enumerate all k-fault configurations for k <= max_faults, +//! - XOR detector / observable effects via `fault_configurations(k)`, +//! - aggregate `configuration_probability` into a lookup table. +//! +//! The circuit builder below intentionally uses a simple sequential stabilizer +//! extraction schedule. The point of the example is the fault-catalog lookup +//! aggregation path, not the optimized surface-code scheduling used by the +//! larger sweep scripts. +//! +//! Run from the PECOS repo root: +//! +//! ```text +//! cargo run -p pecos-qec --example surface_d3_fault_catalog_lookup +//! ``` + +use pecos_qec::SurfaceCode; +use pecos_qec::fault_tolerance::fault_sampler::{ + FaultCatalog, StochasticNoiseParams, build_fault_catalog, +}; +use pecos_quantum::{Attribute, TickCircuit, TickMeasRef}; +use std::collections::BTreeMap; +use std::time::Instant; + +type Syndrome = Vec; +type Logical = Vec; +type LogicalWeights = BTreeMap; +type LookupWeights = BTreeMap; + +#[derive(Debug)] +struct MemoryCircuit { + circuit: TickCircuit, + num_detectors: usize, + num_observables: usize, +} + +fn main() -> Result<(), Box> { + let distance = 3; + let rounds = 3; + let max_faults = 2; + let p = 0.001; + + let memory = build_d3_z_memory_circuit(rounds)?; + let noise = StochasticNoiseParams { + p1: p / 10.0, + p2: p, + p_meas: p, + p_prep: p, + }; + + println!("d={distance} rotated surface-code Z-memory experiment"); + println!( + "rounds={rounds}, detectors={}, observables={}", + memory.num_detectors, memory.num_observables + ); + println!( + "noise: p1={:.3e}, p2={:.3e}, p_meas={:.3e}, p_prep={:.3e}", + noise.p1, noise.p2, noise.p_meas, noise.p_prep + ); + + let catalog = build_fault_catalog(&memory.circuit, &noise)?; + let total_alternatives: usize = catalog + .locations + .iter() + .map(|loc| loc.num_alternatives) + .sum(); + + println!( + "catalog: {} locations, {total_alternatives} single-location alternatives", + catalog.locations.len() + ); + + let started = Instant::now(); + let (weights, configs_by_weight) = build_lookup_weights(&catalog, max_faults); + let decoder = choose_most_likely_logicals(&weights); + let elapsed = started.elapsed(); + + println!("enumerated configurations:"); + for (k, count) in configs_by_weight { + println!(" k={k}: {count}"); + } + println!( + "lookup table: {} syndromes covered, built in {:.3?}", + decoder.len(), + elapsed + ); + + print_top_syndromes(&weights, &decoder, 10); + + Ok(()) +} + +fn build_lookup_weights( + catalog: &FaultCatalog, + max_faults: usize, +) -> (LookupWeights, Vec<(usize, usize)>) { + let mut weights: LookupWeights = BTreeMap::new(); + let mut configs_by_weight = Vec::new(); + + for k in 0..=max_faults { + let mut count = 0usize; + for event in catalog.fault_configurations(k) { + add_lookup_weight( + &mut weights, + event.affected_detectors, + event.affected_observables, + event.configuration_probability, + ); + count += 1; + } + configs_by_weight.push((k, count)); + } + + (weights, configs_by_weight) +} + +fn add_lookup_weight( + weights: &mut LookupWeights, + syndrome: Syndrome, + logical: Logical, + probability: f64, +) { + weights + .entry(syndrome) + .or_default() + .entry(logical) + .and_modify(|p| *p += probability) + .or_insert(probability); +} + +fn choose_most_likely_logicals(weights: &LookupWeights) -> BTreeMap { + weights + .iter() + .map(|(syndrome, logical_weights)| { + let best_logical = logical_weights + .iter() + .max_by(|(_, a), (_, b)| a.total_cmp(b)) + .map(|(logical, _)| logical.clone()) + .unwrap_or_default(); + (syndrome.clone(), best_logical) + }) + .collect() +} + +fn print_top_syndromes( + weights: &LookupWeights, + decoder: &BTreeMap, + limit: usize, +) { + let mut rows: Vec<_> = weights + .iter() + .map(|(syndrome, logical_weights)| { + let total_p: f64 = logical_weights.values().sum(); + (total_p, syndrome, logical_weights) + }) + .collect(); + rows.sort_by(|(a, _, _), (b, _, _)| b.total_cmp(a)); + + println!(); + println!("top {limit} syndrome classes by truncated probability:"); + for (rank, (total_p, syndrome, logical_weights)) in rows.into_iter().take(limit).enumerate() { + let correction = decoder.get(syndrome).cloned().unwrap_or_default(); + let no_logical = logical_weights.get(&Vec::new()).copied().unwrap_or(0.0); + let logical_total = total_p - no_logical; + println!( + " {:>2}. syndrome={:?} total={:.6e} logical_weight={:.6e} correction={:?}", + rank + 1, + syndrome, + total_p, + logical_total, + correction + ); + } +} + +fn build_d3_z_memory_circuit(rounds: usize) -> Result { + let code = SurfaceCode::rotated(3)?; + let num_data = code.num_data_qubits(); + let x_ancilla_offset = num_data; + let z_ancilla_offset = x_ancilla_offset + code.num_x_stabilizers(); + + let x_ancilla = |idx: usize| x_ancilla_offset + idx; + let z_ancilla = |idx: usize| z_ancilla_offset + idx; + + let mut circuit = TickCircuit::new(); + let data_qubits: Vec = (0..num_data).collect(); + circuit.tick().pz(&data_qubits); + + let mut x_round_measurements: Vec> = Vec::with_capacity(rounds); + let mut z_round_measurements: Vec> = Vec::with_capacity(rounds); + + for _round in 0..rounds { + let x_ancillas: Vec = (0..code.num_x_stabilizers()).map(x_ancilla).collect(); + let z_ancillas: Vec = (0..code.num_z_stabilizers()).map(z_ancilla).collect(); + + circuit.tick().pz(&x_ancillas); + circuit.tick().pz(&z_ancillas); + circuit.tick().h(&x_ancillas); + + for check in code.x_stabilizers() { + let anc = x_ancilla(check.index); + for data in check.qubits() { + circuit.tick().cx(&[(anc, data)]); + } + } + + for check in code.z_stabilizers() { + let anc = z_ancilla(check.index); + for data in check.qubits() { + circuit.tick().cx(&[(data, anc)]); + } + } + + circuit.tick().h(&x_ancillas); + + let x_refs = circuit.tick().mz(&x_ancillas); + let z_refs = circuit.tick().mz(&z_ancillas); + x_round_measurements.push(x_refs); + z_round_measurements.push(z_refs); + } + + let final_data_measurements = circuit.tick().mz(&data_qubits); + let num_measurements = circuit.num_measurements(); + + let mut detectors: Vec> = Vec::new(); + + // Initial Z-basis boundary detectors: data starts in |0...0>, so the first + // Z-check round is deterministic. Without these, an initial data X fault can + // flip every repeated Z-check round and the final data parity, cancelling all + // later detectors. + for stab_idx in 0..code.num_z_stabilizers() { + detectors.push(relative_records( + num_measurements, + &[z_round_measurements[0][stab_idx]], + )); + } + + // Repeated syndrome detectors: current stabilizer measurement XOR previous + // stabilizer measurement. These are deterministic after the first round. + for round in 1..rounds { + for stab_idx in 0..code.num_x_stabilizers() { + detectors.push(relative_records( + num_measurements, + &[ + x_round_measurements[round][stab_idx], + x_round_measurements[round - 1][stab_idx], + ], + )); + } + for stab_idx in 0..code.num_z_stabilizers() { + detectors.push(relative_records( + num_measurements, + &[ + z_round_measurements[round][stab_idx], + z_round_measurements[round - 1][stab_idx], + ], + )); + } + } + + // Final Z-basis detectors: last Z-stabilizer result XOR the final data + // measurements in that stabilizer support. + let last_round = rounds - 1; + for check in code.z_stabilizers() { + let mut refs = vec![z_round_measurements[last_round][check.index]]; + refs.extend( + check + .qubits() + .into_iter() + .map(|q| final_data_measurements[q]), + ); + detectors.push(relative_records(num_measurements, &refs)); + } + + let logical_z_refs: Vec = code + .logical_z() + .data_qubits + .iter() + .map(|&q| final_data_measurements[q]) + .collect(); + let observables = vec![relative_records(num_measurements, &logical_z_refs)]; + + circuit.set_meta( + "num_measurements", + Attribute::String(num_measurements.to_string()), + ); + circuit.set_meta("detectors", Attribute::String(records_json(&detectors))); + circuit.set_meta("observables", Attribute::String(records_json(&observables))); + + Ok(MemoryCircuit { + circuit, + num_detectors: detectors.len(), + num_observables: observables.len(), + }) +} + +fn relative_records(num_measurements: usize, refs: &[TickMeasRef]) -> Vec { + refs.iter() + .map(|m| m.record_idx as i32 - num_measurements as i32) + .collect() +} + +fn records_json(records: &[Vec]) -> String { + let entries: Vec = records + .iter() + .map(|rs| { + let values = rs.iter().map(i32::to_string).collect::>().join(","); + format!(r#"{{"records":[{values}]}}"#) + }) + .collect(); + format!("[{}]", entries.join(",")) +} + +#[cfg(test)] +mod tests { + use super::*; + use pecos_qec::fault_tolerance::targeted_lookup_decoder::TargetedLookupDecoder; + use std::collections::BTreeSet; + + #[test] + fn accumulates_repeated_logical_weights_for_a_syndrome() { + let mut weights = LookupWeights::new(); + + add_lookup_weight(&mut weights, vec![1, 3], vec![0], 0.125); + add_lookup_weight(&mut weights, vec![1, 3], vec![0], 0.375); + add_lookup_weight(&mut weights, vec![1, 3], Vec::new(), 0.250); + + assert_close(weights[&vec![1, 3]][&vec![0]], 0.500); + assert_close(weights[&vec![1, 3]][&Vec::new()], 0.250); + } + + #[test] + fn decoder_picks_most_likely_logical_per_syndrome() { + let mut weights = LookupWeights::new(); + + add_lookup_weight(&mut weights, Vec::new(), Vec::new(), 0.900); + add_lookup_weight(&mut weights, Vec::new(), vec![0], 0.100); + add_lookup_weight(&mut weights, vec![2], Vec::new(), 0.200); + add_lookup_weight(&mut weights, vec![2], vec![0], 0.700); + + let decoder = choose_most_likely_logicals(&weights); + + assert_eq!(decoder[&Vec::new()], Vec::::new()); + assert_eq!(decoder[&vec![2]], vec![0]); + } + + #[test] + fn small_catalog_lookup_matches_hand_calculation() { + let mut circuit = TickCircuit::new(); + circuit.tick().h(&[0]); + circuit.tick().mz(&[0]); + circuit.set_meta("num_measurements", Attribute::String("1".to_string())); + circuit.set_meta( + "detectors", + Attribute::String(r#"[{"records":[-1]}]"#.to_string()), + ); + circuit.set_meta( + "observables", + Attribute::String(r#"[{"records":[-1]}]"#.to_string()), + ); + + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&circuit, &noise).unwrap(); + let (weights, counts) = build_lookup_weights(&catalog, 1); + let decoder = choose_most_likely_logicals(&weights); + + assert_eq!(counts, vec![(0, 1), (1, 4)]); + + // k=0 no fault: 0.97 * 0.99 = 0.9603. + // k=1 no-effect H alternative: (0.03 / 3) * 0.99 = 0.0099. + assert_close(weights[&Vec::new()][&Vec::new()], 0.9702); + + // k=1 detector+logical events: + // two H alternatives flip MZ: 2 * (0.03 / 3) * 0.99 = 0.0198. + // one MZ flip: 0.01 * 0.97 = 0.0097. + assert_close(weights[&vec![0]][&vec![0]], 0.0295); + + assert_eq!(decoder[&Vec::new()], Vec::::new()); + assert_eq!(decoder[&vec![0]], vec![0]); + } + + #[test] + fn small_catalog_decoder_corrects_every_truncated_event() { + let mut circuit = TickCircuit::new(); + circuit.tick().h(&[0]); + circuit.tick().mz(&[0]); + circuit.set_meta("num_measurements", Attribute::String("1".to_string())); + circuit.set_meta( + "detectors", + Attribute::String(r#"[{"records":[-1]}]"#.to_string()), + ); + circuit.set_meta( + "observables", + Attribute::String(r#"[{"records":[-1]}]"#.to_string()), + ); + + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&circuit, &noise).unwrap(); + let (weights, _) = build_lookup_weights(&catalog, 1); + let decoder = choose_most_likely_logicals(&weights); + + let mut decoded = 0usize; + for k in 0..=1 { + for event in catalog.fault_configurations(k) { + let correction = decoder + .get(&event.affected_detectors) + .expect("decoder should cover every truncated syndrome"); + let residual = xor_parity(&event.affected_observables, correction); + assert!( + residual.is_empty(), + "failed to decode syndrome {:?}: event logical {:?}, correction {:?}", + event.affected_detectors, + event.affected_observables, + correction + ); + decoded += 1; + } + } + + assert_eq!(decoded, 5); + } + + #[test] + fn d3_surface_lookup_builds_nontrivial_weight_one_table() { + let memory = build_d3_z_memory_circuit(3).unwrap(); + let noise = StochasticNoiseParams { + p1: 0.0001, + p2: 0.001, + p_meas: 0.001, + p_prep: 0.001, + }; + let catalog = build_fault_catalog(&memory.circuit, &noise).unwrap(); + let (weights, counts) = build_lookup_weights(&catalog, 1); + let decoder = choose_most_likely_logicals(&weights); + + assert_eq!(memory.num_detectors, 24); + assert_eq!(memory.num_observables, 1); + assert_eq!(counts[0], (0, 1)); + assert_eq!(counts[1].0, 1); + assert!(counts[1].1 > 1_000); + assert!(weights.len() > 10); + assert_eq!(decoder[&Vec::new()], Vec::::new()); + } + + #[test] + fn d3_surface_weight_one_decoder_corrects_weight_one_events() { + let memory = build_d3_z_memory_circuit(3).unwrap(); + let noise = StochasticNoiseParams { + p1: 0.0001, + p2: 0.001, + p_meas: 0.001, + p_prep: 0.001, + }; + let catalog = build_fault_catalog(&memory.circuit, &noise).unwrap(); + let (weights, _) = build_lookup_weights(&catalog, 1); + let decoder = choose_most_likely_logicals(&weights); + + let mut checked = 0usize; + for k in 0..=1 { + for event in catalog.fault_configurations(k) { + let correction = decoder + .get(&event.affected_detectors) + .expect("decoder should cover every weight-one syndrome"); + let residual = xor_parity(&event.affected_observables, correction); + assert!( + residual.is_empty(), + "failed to decode syndrome {:?}: event logical {:?}, correction {:?}", + event.affected_detectors, + event.affected_observables, + correction + ); + checked += 1; + } + } + + assert_eq!( + checked, + 1 + catalog + .locations + .iter() + .map(|loc| loc.num_alternatives) + .sum::() + ); + } + + #[test] + fn targeted_decoder_matches_bruteforce_on_real_d3_surface_catalog() { + let memory = build_d3_z_memory_circuit(3).unwrap(); + let noise = StochasticNoiseParams { + p1: 0.0001, + p2: 0.001, + p_meas: 0.001, + p_prep: 0.001, + }; + let catalog = build_fault_catalog(&memory.circuit, &noise).unwrap(); + let decoder = TargetedLookupDecoder::new(&catalog).max_faults(1); + let base_probability = decoder.base_probability(); + + let mut syndromes = BTreeSet::new(); + syndromes.insert(Vec::new()); + for event in catalog.fault_configurations(1) { + if !event.affected_detectors.is_empty() { + syndromes.insert(event.affected_detectors); + } + if syndromes.len() >= 8 { + break; + } + } + assert!( + syndromes.len() >= 4, + "surface catalog should expose several non-empty weight-one syndromes" + ); + + for syndrome in syndromes { + let result = decoder.decode(&syndrome); + let expected = brute_force_odds_for_syndrome(&catalog, 1, &syndrome, base_probability); + assert_eq!(result.syndrome, syndrome); + assert_logical_weights_close(&result.logical_weights, &expected); + + let expected_best = expected + .iter() + .max_by(|(_, a), (_, b)| a.total_cmp(b)) + .map(|(logical, _)| logical.clone()) + .unwrap_or_default(); + assert_eq!(result.best_logical, expected_best); + } + } + + fn brute_force_odds_for_syndrome( + catalog: &FaultCatalog, + max_faults: usize, + syndrome: &[usize], + base_probability: f64, + ) -> LogicalWeights { + let mut weights = LogicalWeights::new(); + for k in 0..=max_faults { + for event in catalog.fault_configurations(k) { + if event.affected_detectors == syndrome { + let odds = event.configuration_probability / base_probability; + weights + .entry(event.affected_observables) + .and_modify(|w| *w += odds) + .or_insert(odds); + } + } + } + weights + } + + fn assert_logical_weights_close(actual: &LogicalWeights, expected: &LogicalWeights) { + assert_eq!( + actual.keys().collect::>(), + expected.keys().collect::>() + ); + for (logical, expected_weight) in expected { + let actual_weight = actual[logical]; + let scale = expected_weight.abs().max(1e-15); + assert!( + (actual_weight - expected_weight).abs() / scale < 1e-10, + "logical={logical:?}: expected {expected_weight:.12e}, got {actual_weight:.12e}" + ); + } + } + + fn assert_close(actual: f64, expected: f64) { + assert!( + (actual - expected).abs() < 1e-12, + "expected {expected}, got {actual}" + ); + } + + fn xor_parity(a: &[usize], b: &[usize]) -> Vec { + let mut out = std::collections::BTreeSet::new(); + for value in a.iter().chain(b.iter()) { + if !out.remove(value) { + out.insert(*value); + } + } + out.into_iter().collect() + } +} diff --git a/examples/surface/decoder_comparison.py b/examples/surface/decoder_comparison.py new file mode 100644 index 000000000..d1b9ea91d --- /dev/null +++ b/examples/surface/decoder_comparison.py @@ -0,0 +1,542 @@ +r"""Decoder comparison: same samples, multiple decoders, one table. + +Generates DEM samples once per (distance, error_rate, rounds) point and +decodes them with every requested decoder. Produces an HTML report with +comparison tables showing logical error rates and decode throughput. + +This is complementary to ``native_dem_threshold_sweep.py`` which produces +threshold curves. This script answers "which decoder is best at a given +operating point?" with a controlled experiment (identical samples). + +Example: + python examples/surface/decoder_comparison.py + + python examples/surface/decoder_comparison.py \\ + --distances 3 5 7 \\ + --error-rates 0.004 0.008 \\ + --shots 2000 \\ + --decoders pymatching tesseract bp_osd \\ + --open-html +""" + +from __future__ import annotations + +import argparse +import html +import json +import time +from dataclasses import asdict, dataclass +from pathlib import Path +from textwrap import dedent +from typing import TYPE_CHECKING + +if TYPE_CHECKING: + from pecos.qec.surface import NoiseModel + + +@dataclass +class DecoderResult: + """Result for one decoder at one operating point.""" + + decoder: str + distance: int + basis: str + physical_error_rate: float + num_rounds: int + num_shots: int + num_errors: int + logical_error_rate: float + decode_seconds: float + shots_per_second: float + per_shot_median: float = 0.0 + per_shot_p99: float = 0.0 + per_shot_max: float = 0.0 + + +@dataclass +class ComparisonPoint: + """All decoder results for one (distance, p, rounds) point.""" + + distance: int + basis: str + physical_error_rate: float + num_rounds: int + num_shots: int + sample_seconds: float + results: list[DecoderResult] + + +def _build_sampler( + distance: int, + num_rounds: int, + noise: NoiseModel, + basis: str, + circuit_source: str, +) -> tuple: + """Build the native sampler and get DEM strings.""" + from pecos.qec.surface import SurfacePatch, build_native_sampler + from pecos.qec.surface.decode import SurfaceDecoder, generate_circuit_level_dem_from_builder + + patch = SurfacePatch.create(distance=distance) + sampler = build_native_sampler( + patch, + num_rounds, + noise, + basis=basis, + circuit_source=circuit_source, + ) + + # Decomposed DEM for MWPM decoders + dec = SurfaceDecoder( + patch, + num_rounds=num_rounds, + noise=noise, + decoder_type="pymatching", + use_circuit_level_dem=True, + circuit_level_dem_mode="native_decomposed", + circuit_level_dem_source=circuit_source, + ) + dem_decomp = dec.get_dem(basis.upper(), circuit_level=True) + dem_decomp = "\n".join(line for line in dem_decomp.split("\n") if not line.startswith("logical_observable")) + + # Full DEM for non-MWPM decoders + dem_full = generate_circuit_level_dem_from_builder( + patch, + num_rounds, + noise, + basis=basis, + decompose_errors=False, + circuit_source=circuit_source, + ) + dem_full = "\n".join(line for line in dem_full.split("\n") if not line.startswith("logical_observable")) + + return sampler, dem_decomp, dem_full + + +# Decoders that need decomposed (graphlike) DEMs +# MWPM decoders get decomposed DEMs. DemMatchingGraph handles fault-ID-aware +# merging with first-observable-wins (matching PyMatching's INDEPENDENT strategy). +_MWPM_DECODERS = { + "pymatching", + "pymatching_uncorrelated", + "fusion_blossom", + "fusion_blossom_serial", + "fusion_blossom_parallel", + "pecos_uf", + "pecos_uf_correlated", + "pecos_uf:balanced", + "pecos_uf:fast", + "pecos_uf:bp", + "windowed", +} + +# All supported decoders +_ALL_DECODERS = [ + "pymatching", + "pymatching_uncorrelated", + "fusion_blossom", + "fusion_blossom_serial", + "fusion_blossom_parallel", + "tesseract", + "mwpf", + "bp_osd", + "union_find", + "min_sum_bp", + "relay_bp", + "pecos_uf", + "pecos_uf:balanced", + "pecos_uf:bp", + "pecos_uf_correlated", # legacy alias for pecos_uf:balanced +] + +# Decoders where parallel decoding helps +_SLOW_DECODERS = {"tesseract", "mwpf", "bp_osd", "relay_bp"} + + +def _decoder_base_name(name: str) -> str: + """Extract base decoder name, stripping config suffix (e.g. 'mwpf:c=30' -> 'mwpf').""" + return name.split(":", maxsplit=1)[0] + + +def run_comparison( + *, + distances: list[int], + error_rates: list[float], + decoders: list[str], + basis: str, + shots: int, + seed: int, + circuit_source: str, + p1_scale: float, + p_meas_scale: float, + p_prep_scale: float, +) -> list[ComparisonPoint]: + """Run the full comparison and return results.""" + from pecos.qec.surface import NoiseModel + + points: list[ComparisonPoint] = [] + total_configs = len(distances) * len(error_rates) + config_idx = 0 + + for distance in distances: + num_rounds = 2 * distance + for p in error_rates: + config_idx += 1 + noise = NoiseModel( + p1=p * p1_scale, + p2=p, + p_meas=p * p_meas_scale, + p_prep=p * p_prep_scale, + ) + + print(f"[{config_idx}/{total_configs}] d={distance} p={p:.4g} r={num_rounds} ...") + + sampler, dem_decomp, dem_full = _build_sampler( + distance, + num_rounds, + noise, + basis, + circuit_source, + ) + + # Generate samples once + t0 = time.perf_counter() + sample_batch = sampler.sampler.generate_samples(shots, seed=seed + config_idx) + sample_seconds = time.perf_counter() - t0 + + results: list[DecoderResult] = [] + for decoder_name in decoders: + base = _decoder_base_name(decoder_name) + # Ensemble uses decomposed DEMs (all ensemble members are matching-graph decoders) + dem = dem_decomp if base in _MWPM_DECODERS or base == "ensemble" else dem_full + + if base in _SLOW_DECODERS: + stats = sample_batch.decode_stats_parallel(dem, decoder_name) + else: + stats = sample_batch.decode_stats(dem, decoder_name) + + results.append( + DecoderResult( + decoder=decoder_name, + distance=distance, + basis=basis.upper(), + physical_error_rate=p, + num_rounds=num_rounds, + num_shots=shots, + num_errors=stats.num_errors, + logical_error_rate=stats.logical_error_rate, + decode_seconds=stats.total_seconds, + shots_per_second=shots / stats.total_seconds if stats.total_seconds > 0 else float("inf"), + per_shot_median=stats.per_shot_median, + per_shot_p99=stats.per_shot_p99, + per_shot_max=stats.per_shot_max, + ), + ) + print( + f" {decoder_name:14s}: {stats.num_errors:>4d}/{shots} " + f"LER={stats.logical_error_rate:.4f} " + f"mean={stats.per_shot_mean:.1e}s " + f"median={stats.per_shot_median:.1e}s " + f"p99={stats.per_shot_p99:.1e}s " + f"max={stats.per_shot_max:.1e}s", + ) + + points.append( + ComparisonPoint( + distance=distance, + basis=basis.upper(), + physical_error_rate=p, + num_rounds=num_rounds, + num_shots=shots, + sample_seconds=sample_seconds, + results=results, + ), + ) + + return points + + +def write_json(path: Path, points: list[ComparisonPoint], config: dict) -> None: + """Write results as JSON.""" + data = { + "config": config, + "points": [asdict(p) for p in points], + } + path.write_text(json.dumps(data, indent=2)) + print(f"Wrote JSON to {path}") + + +def write_html(path: Path, points: list[ComparisonPoint], config: dict) -> None: + """Write an HTML report with comparison tables.""" + style = dedent(""" + :root { + color-scheme: light dark; + --bg: #f8fafc; --fg: #0f172a; + --hero-bg: linear-gradient(135deg, #e0f2fe, #f8fafc 55%, #dcfce7); + --card-bg: white; --card-border: #dbeafe; --card-shadow: rgba(15,23,42,0.05); + --meta-bg: rgba(255,255,255,0.82); + --muted: #475569; --link: #2563eb; + --table-stripe: #f1f5f9; --table-border: #e2e8f0; + } + [data-theme="dark"] { + --bg: #0f172a; --fg: #e2e8f0; + --hero-bg: linear-gradient(135deg, #1e293b, #0f172a 55%, #1a2e1a); + --card-bg: #1e293b; --card-border: #334155; --card-shadow: rgba(0,0,0,0.3); + --meta-bg: rgba(30,41,59,0.82); + --muted: #94a3b8; --link: #60a5fa; + --table-stripe: #0f172a; --table-border: #334155; + } + @media (prefers-color-scheme: dark) { + :root:not([data-theme="light"]) { + --bg: #0f172a; --fg: #e2e8f0; + --hero-bg: linear-gradient(135deg, #1e293b, #0f172a 55%, #1a2e1a); + --card-bg: #1e293b; --card-border: #334155; --card-shadow: rgba(0,0,0,0.3); + --meta-bg: rgba(30,41,59,0.82); + --muted: #94a3b8; --link: #60a5fa; + --table-stripe: #0f172a; --table-border: #334155; + } + } + body { + margin: 0; + font-family: ui-sans-serif, -apple-system, BlinkMacSystemFont, sans-serif; + background: var(--bg); color: var(--fg); + } + main { max-width: 1400px; margin: 0 auto; padding: 32px 24px 56px; } + h1, h2, h3, p { margin-top: 0; } + .theme-toggle { + position: fixed; top: 16px; right: 16px; z-index: 100; + background: var(--card-bg); border: 1px solid var(--card-border); + border-radius: 8px; padding: 6px 12px; cursor: pointer; + color: var(--fg); font-size: 0.85rem; font-weight: 600; + } + .theme-toggle:hover { opacity: 0.8; } + .hero { + background: var(--hero-bg); + border: 1px solid var(--card-border); + border-radius: 20px; + padding: 24px; + margin-bottom: 24px; + } + .meta { + display: grid; + grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); + gap: 12px; + margin-top: 18px; + } + .meta-card { + background: var(--meta-bg); + border: 1px solid var(--card-border); + border-radius: 14px; + padding: 14px 16px; + } + .meta-card strong { + display: block; font-size: 0.82rem; text-transform: uppercase; + letter-spacing: 0.04em; color: var(--muted); margin-bottom: 6px; + } + .section { + background: var(--card-bg); + border: 1px solid var(--card-border); + border-radius: 18px; + padding: 20px 22px; + margin-top: 20px; + box-shadow: 0 10px 24px var(--card-shadow); + overflow-x: auto; + } + table { border-collapse: collapse; width: 100%; margin: 12px 0 0; } + th, td { padding: 10px 14px; text-align: right; border-bottom: 1px solid var(--table-border); } + th { + font-size: 0.82rem; text-transform: uppercase; + letter-spacing: 0.03em; color: var(--muted); border-bottom-width: 2px; + } + td:first-child, th:first-child { text-align: left; } + tr:nth-child(even) td { background: var(--table-stripe); } + code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; } + """).strip() + + def meta_card(label: str, value: str) -> str: + return f'
{html.escape(label)}{html.escape(value)}
' + + decoders = config.get("decoders", []) + p1s = config.get("p1_scale", 1 / 30) + pms = config.get("p_meas_scale", 1 / 3) + pps = config.get("p_prep_scale", 1 / 3) + noise_str = f"p1={p1s:.4g}*p, p2=p, p_meas={pms:.4g}*p, p_prep={pps:.4g}*p" + parts = [ + "", + '', + "", + ' ', + ' ', + " PECOS Decoder Comparison", + f" ", + "", + "", + '', + "
", + '
', + "

PECOS Decoder Comparison

", + "

Same samples decoded by multiple decoders. LER differences reflect " + "decoder quality, not sampling noise.

", + '
', + meta_card("Decoders", ", ".join(decoders)), + meta_card("Distances", ", ".join(str(d) for d in config.get("distances", []))), + meta_card("Error Rates", ", ".join(f"{p:.4g}" for p in config.get("error_rates", []))), + meta_card("Shots", str(config.get("shots", 0))), + meta_card("Basis", config.get("basis", "Z")), + meta_card("Noise Model", noise_str), + meta_card("Circuit Source", config.get("circuit_source", "traced_qis")), + "
", + "
", + ] + + # Group by (distance, p) + for point in points: + d = point.distance + p = point.physical_error_rate + r = point.num_rounds + parts.append('
') + parts.append(f"

d={d}, p={p:.4g}, rounds={r} ({point.num_shots} shots)

") + + parts.append(" ") + parts.append( + " " + "", + ) + for res in sorted(point.results, key=lambda r: r.logical_error_rate): + mean_s = res.decode_seconds / res.num_shots if res.num_shots > 0 else 0 + sps = f"{res.shots_per_second:.1e}" + ler = res.logical_error_rate + n = res.num_shots + z = 1.96 + if n > 0 and 0 < ler < 1: + denom = 1 + z * z / n + center = (ler + z * z / (2 * n)) / denom + half = z * (ler * (1 - ler) / n + z * z / (4 * n * n)) ** 0.5 / denom + ci_lo, ci_hi = max(0, center - half), min(1, center + half) + elif n > 0: + ci_lo, ci_hi = ler, ler + else: + ci_lo, ci_hi = 0, 0 + ler_str = f"{ler:.4f} ({ci_lo:.4f} - {ci_hi:.4f})" + parts.append( + f" " + f"" + f"" + f"" + f"" + f"" + f"" + f"" + f"", + ) + parts.append("
DecoderLER (95% CI)MeanMedianp99MaxThroughput
{html.escape(res.decoder)}{ler_str}{mean_s:.1e} s{res.per_shot_median:.1e} s{res.per_shot_p99:.1e} s{res.per_shot_max:.1e} s{sps} shots/s
") + parts.append("
") + + parts.extend( + [ + "
", + dedent(""" + + """).strip(), + "", + "", + ], + ) + + path.write_text("\n".join(parts)) + print(f"Wrote HTML to {path}") + + +def main() -> int: + """CLI entry point for decoder comparison.""" + parser = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter) + parser.add_argument("--distances", nargs="+", type=int, default=[3, 5]) + parser.add_argument("--error-rates", nargs="+", type=float, default=[0.004, 0.008]) + parser.add_argument("--shots", type=int, default=1000) + parser.add_argument("--basis", default="Z") + parser.add_argument("--seed", type=int, default=42) + parser.add_argument( + "--decoders", + nargs="+", + default=["pymatching", "tesseract", "bp_osd"], + help=f"Decoders to compare. Available: {', '.join(_ALL_DECODERS)}", + ) + parser.add_argument("--circuit-source", default="traced_qis", choices=["traced_qis", "abstract"]) + parser.add_argument("--p1-scale", type=float, default=1.0 / 30.0) + parser.add_argument("--p-meas-scale", type=float, default=1.0 / 3.0) + parser.add_argument("--p-prep-scale", type=float, default=1.0 / 3.0) + parser.add_argument("--output-dir", type=str, default=None) + parser.add_argument("--open-html", action="store_true") + args = parser.parse_args() + + config = { + "distances": sorted(args.distances), + "error_rates": sorted(args.error_rates), + "shots": args.shots, + "basis": args.basis.upper(), + "decoders": args.decoders, + "circuit_source": args.circuit_source, + "p1_scale": args.p1_scale, + "p_meas_scale": args.p_meas_scale, + "p_prep_scale": args.p_prep_scale, + } + + print("PECOS Decoder Comparison") + print("=" * 40) + for k, v in config.items(): + print(f" {k}: {v}") + print() + + t0 = time.perf_counter() + points = run_comparison( + distances=sorted(args.distances), + error_rates=sorted(args.error_rates), + decoders=args.decoders, + basis=args.basis, + shots=args.shots, + seed=args.seed, + circuit_source=args.circuit_source, + p1_scale=args.p1_scale, + p_meas_scale=args.p_meas_scale, + p_prep_scale=args.p_prep_scale, + ) + elapsed = time.perf_counter() - t0 + print(f"\nTotal time: {elapsed:.1f}s") + + if args.output_dir: + out = Path(args.output_dir) + else: + import tempfile + + out = Path(tempfile.mkdtemp(prefix="pecos_decoder_comparison_")) + + out.mkdir(parents=True, exist_ok=True) + write_json(out / "decoder_comparison.json", points, config) + html_path = out / "decoder_comparison.html" + write_html(html_path, points, config) + + if args.open_html: + import webbrowser + + webbrowser.open(html_path.as_uri()) + print(f"Opened {html_path}") + + return 0 + + +if __name__ == "__main__": + raise SystemExit(main()) diff --git a/examples/surface/dem_comparison.py b/examples/surface/dem_comparison.py new file mode 100644 index 000000000..9ec8838d9 --- /dev/null +++ b/examples/surface/dem_comparison.py @@ -0,0 +1,203 @@ +r"""Compare ALL DEM generation methods against simulation ground truth. + +Compares per-detector firing rates from: + 1. Non-EEG DemBuilder (backward Pauli propagation) + 2. DemSampler.from_circuit (separate DEM path) + 3. Backward Heisenberg EEG (exact for coherent, handles depol via attenuation) + 4. stabilizer() simulation (SparseStab, exact for depol, any distance) + 5. statevec() simulation (exact for everything, limited to small circuits) + +Example: + uv run python examples/surface/dem_comparison.py + uv run python examples/surface/dem_comparison.py -d 2 3 --p 0.005 --shots 20000 + uv run python examples/surface/dem_comparison.py -d 5 --no-statevec +""" + +from __future__ import annotations + +import argparse +import json +import math +import sys +import time +from pathlib import Path + +sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "python" / "quantum-pecos" / "src")) + + +def run(*, distance, rounds, basis, p, shots, seed, run_statevec): + from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch + from pecos_rslib.qec import DemBuilder, DagFaultAnalyzer, DemSampler + from pecos_rslib_exp import ( + exact_detection_rates, + sim_neo, + stabilizer, + statevec, + depolarizing, + ) + + patch = SurfacePatch.create(distance=distance) + b = LogicalCircuitBuilder() + b.add_patch(patch, "Q0") + b.add_memory("Q0", rounds=rounds, basis=basis) + tc = b.to_tick_circuit() + dag = tc.to_dag_circuit() + + det_json = json.loads(tc.get_meta("detectors")) + num_meas = int(tc.get_meta("num_measurements")) + num_dets = len(det_json) + + print(f"\n{'='*80}") + print(f"d={distance} {basis}-basis, {rounds} rounds, {num_dets} dets, p={p} (depol only)") + print(f"{'='*80}") + + def extract_det_rates(results): + rates = [0.0] * num_dets + for r in results: + meas = list(r) + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + rates[i] += 1.0 / len(results) + return rates + + # 1. Non-EEG DemBuilder analytical marginals + t0 = time.perf_counter() + analyzer = DagFaultAnalyzer(dag) + influence = analyzer.build_influence_map() + dem_obj = ( + DemBuilder(influence) + .with_noise(p1=p, p2=p, p_meas=p, p_prep=p) + .with_detectors_json(tc.get_meta("detectors")) + .with_observables_json(tc.get_meta("observables")) + .with_num_measurements(num_meas) + .build() + ) + dem_str = dem_obj.to_string() + dem_analytical = [0.0] * num_dets + for line in dem_str.strip().split("\n"): + if line.startswith("error("): + prob = float(line.split("(")[1].split(")")[0]) + for x in line.split(): + if x.startswith("D"): + d_id = int(x[1:]) + if d_id < num_dets: + dem_analytical[d_id] += prob + dem_build_time = time.perf_counter() - t0 + + # 2. DemSampler.from_circuit + t0 = time.perf_counter() + sampler_fc = DemSampler.from_circuit(dag, p1=p, p2=p, p_meas=p, p_prep=p) + batch_fc = sampler_fc.generate_samples(num_shots=shots, seed=seed) + dem_fc = [0.0] * num_dets + for i in range(shots): + syn = batch_fc.get_syndrome(i) + for dd in range(min(num_dets, len(syn))): + if syn[dd]: + dem_fc[dd] += 1.0 / shots + fc_time = time.perf_counter() - t0 + + # 3. Backward Heisenberg + t0 = time.perf_counter() + heis_results = exact_detection_rates(tc, p1=p, p2=p, p_meas=p, p_prep=p) + heis = [0.0] * num_dets + for det_id, prob in heis_results: + if det_id < num_dets: + heis[det_id] = prob + heis_time = time.perf_counter() - t0 + + # 4. stabilizer() ground truth + t0 = time.perf_counter() + noise = depolarizing().p1(p).p2(p).p_meas(p).p_prep(p) + stab_results = sim_neo(tc).quantum(stabilizer()).noise(noise).shots(shots).seed(seed).run() + stab = extract_det_rates(stab_results) + stab_time = time.perf_counter() - t0 + + # 5. statevec() (optional, small circuits only) + sv = None + sv_time = 0 + if run_statevec: + t0 = time.perf_counter() + sv_results = sim_neo(tc).quantum(statevec()).noise(noise).shots(shots).seed(seed + 1).run() + sv = extract_det_rates(sv_results) + sv_time = time.perf_counter() - t0 + + # Print timing + print( + f" DemBuilder: {dem_build_time*1000:.0f}ms, FromCircuit: {fc_time:.2f}s," + f" Heisenberg: {heis_time*1000:.0f}ms, Stabilizer: {stab_time:.2f}s" + + (f", StateVec: {sv_time:.1f}s" if sv else "") + ) + + # Header + cols = ["Det", "DemBuild", "FromCirc", "Heisen", "Stabiliz"] + if sv: + cols.append("StateVec") + cols += ["DB/Stab", "FC/Stab", "H/Stab"] + hdr = f" {cols[0]:>4}" + for c in cols[1:]: + hdr += f" {c:>10}" + print(hdr) + + for dd in range(num_dets): + s = stab[dd] + if s < 0.001: + continue + + se = math.sqrt(s * (1 - s) / shots) + r_db = dem_analytical[dd] / s + r_fc = dem_fc[dd] / s + r_h = heis[dd] / s + + line = f" D{dd:>2} {dem_analytical[dd]:>10.6f} {dem_fc[dd]:>10.6f} {heis[dd]:>10.6f} {s:>10.6f}" + if sv: + line += f" {sv[dd]:>10.6f}" + line += f" {r_db:>10.3f} {r_fc:>10.3f} {r_h:>10.3f}" + + flags = [] + if abs(1 - r_db) > 0.15: + flags.append("DB") + if abs(1 - r_fc) > 0.15: + flags.append("FC") + if abs(1 - r_h) > 0.15: + flags.append("H") + if flags: + line += f" *** {','.join(flags)}" + print(line) + + +def main(): + parser = argparse.ArgumentParser( + description=__doc__, + formatter_class=argparse.RawDescriptionHelpFormatter, + ) + parser.add_argument("--distance", "-d", type=int, nargs="+", default=[2, 3]) + parser.add_argument("--rounds", type=int, default=None) + parser.add_argument("--basis", choices=["X", "Z"], nargs="+", default=["Z"]) + parser.add_argument("--p", type=float, nargs="+", default=[0.005]) + parser.add_argument("--shots", type=int, default=10000) + parser.add_argument("--seed", type=int, default=42) + parser.add_argument("--no-statevec", action="store_true") + args = parser.parse_args() + + for dist in args.distance: + for basis in args.basis: + for p_val in args.p: + rds = args.rounds if args.rounds is not None else dist + run( + distance=dist, + rounds=rds, + basis=basis, + p=p_val, + shots=args.shots, + seed=args.seed, + run_statevec=not args.no_statevec and dist <= 3, + ) + + +if __name__ == "__main__": + main() diff --git a/examples/surface/dem_method_ler_comparison.py b/examples/surface/dem_method_ler_comparison.py new file mode 100644 index 000000000..14f1fc352 --- /dev/null +++ b/examples/surface/dem_method_ler_comparison.py @@ -0,0 +1,420 @@ +r"""DEM method x decoder LER comparison on traced_qis circuits. + +Generates a traced_qis surface code circuit, builds DEMs from multiple +methods, samples once, and decodes with multiple decoders. Reports LER +for each (DEM method, decoder) combination. + +DEM methods: + 1. from_circuit — non-EEG backward Pauli propagation (stochastic only) + 2. coherent_exact — EEG backward Heisenberg + L-BFGS fit + 3. noise_char — EEG unified (correlations + mechanisms + DEM) + 4. perturbative — EEG forward pass (fast, approximate) + +Each method produces a raw DEM string. MWPM decoders (pymatching, +fusion_blossom) use the standard decomposed DEM from ``from_circuit`` +since they cannot handle hyperedges. Non-MWPM decoders (tesseract, +bp_osd) use the raw DEM from each method. + +Example: + uv run python examples/surface/dem_method_ler_comparison.py + uv run python examples/surface/dem_method_ler_comparison.py \ + --distances 3 5 --shots 50000 --decoders pymatching tesseract +""" + +from __future__ import annotations + +import argparse +import sys +import time +from pathlib import Path + +sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "python" / "quantum-pecos" / "src")) + +# Slow decoders that benefit from parallel decoding +SLOW_DECODERS = {"tesseract", "bp_osd"} + + +def _decoder_requires_graphlike(decoder: str) -> bool: + """Check if a decoder requires graphlike (decomposed) DEMs.""" + from pecos_rslib.qec import decoder_dem_requirement + base = decoder.split(":")[0] + return decoder_dem_requirement(base) == "graphlike" + + +def sim_results_to_sample_batch(results, det_json, obs_json, num_meas): + """Convert sim_neo() results to a SampleBatch. + + Computes detection events from detector record XOR definitions, + and observable flips from observable record XOR definitions. + """ + import json + from pecos_rslib.qec import SampleBatch + + dets = det_json if isinstance(det_json, list) else json.loads(det_json) + obs = obs_json if isinstance(obs_json, list) else json.loads(obs_json) + num_dets = len(dets) + num_obs = len(obs) + + detection_events = [] + observable_masks = [] + + for r in results: + meas = list(r) + + # Detection events: XOR of records per detector + syn = [0] * num_dets + for i, det in enumerate(dets): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + syn[i] = val + detection_events.append(syn) + + # Observable flips: XOR of records per observable + obs_mask = 0 + for j, ob in enumerate(obs): + val = 0 + for rec in ob["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + obs_mask |= 1 << j + observable_masks.append(obs_mask) + + return SampleBatch(detection_events, observable_masks) + + +def build_tick_circuits(distance: int, num_rounds: int, basis: str): + """Build both abstract and traced_qis TickCircuits for a surface code. + + Returns (patch, abstract_tc, traced_tc). + EEG methods need the abstract circuit (CX/H gate set). + Non-EEG DemBuilder uses the traced circuit (physical gates). + """ + from pecos.qec.surface import SurfacePatch + from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model + + patch = SurfacePatch.create(distance=distance) + abstract_tc = _build_surface_tick_circuit_for_native_model( + patch, num_rounds, basis, circuit_source="abstract", + ) + traced_tc = _build_surface_tick_circuit_for_native_model( + patch, num_rounds, basis, circuit_source="traced_qis", + ) + return patch, abstract_tc, traced_tc + + +def generate_dems( + abstract_tc, traced_tc, patch, num_rounds, noise_params: dict, basis: str, +) -> list[tuple[str, str, str | None]]: + """Generate DEM strings from all methods. + + EEG methods use the abstract circuit (CX/H gate set). + Non-EEG DemBuilder uses the traced circuit (physical Selene gates). + + Returns list of (method_name, raw_dem, decomposed_dem_or_None). + decomposed_dem is None when the method cannot produce a graphlike DEM. + """ + from pecos.qec.surface import NoiseModel + from pecos.qec.surface.decode import generate_circuit_level_dem_from_builder + + results = [] + + noise = NoiseModel( + p1=noise_params.get("p1", 0.0), + p2=noise_params.get("p2", 0.0), + p_meas=noise_params.get("p_meas", 0.0), + p_prep=noise_params.get("p_prep", 0.0), + ) + + # 1. from_circuit on traced (non-EEG, stochastic, physical gates) + try: + raw = generate_circuit_level_dem_from_builder( + patch, num_rounds, noise, basis=basis, + decompose_errors=False, circuit_source="traced_qis", + ) + decomp = generate_circuit_level_dem_from_builder( + patch, num_rounds, noise, basis=basis, + decompose_errors=True, circuit_source="traced_qis", + ) + results.append(("from_circuit_traced", raw, decomp)) + except Exception as e: + print(f" WARN: from_circuit_traced failed: {e}") + + # 1b. from_circuit on abstract (non-EEG, stochastic, logical gates) + try: + raw = generate_circuit_level_dem_from_builder( + patch, num_rounds, noise, basis=basis, + decompose_errors=False, circuit_source="abstract", + ) + decomp = generate_circuit_level_dem_from_builder( + patch, num_rounds, noise, basis=basis, + decompose_errors=True, circuit_source="abstract", + ) + results.append(("from_circuit_abstract", raw, decomp)) + except Exception as e: + print(f" WARN: from_circuit_abstract failed: {e}") + + # EEG methods use the abstract circuit (CX/H gate set) + # 2. coherent_dem_decomposed (EEG, X/Z Pauli-aware decomposition) + try: + from pecos_rslib_exp import coherent_dem_decomposed + + raw_dem, decomp_dem = coherent_dem_decomposed(abstract_tc, **noise_params) + if raw_dem.strip(): + results.append(("coherent_decomp", raw_dem, decomp_dem)) + except Exception as e: + print(f" WARN: coherent_dem_decomposed failed: {e}") + + # 3. noise_characterization (EEG, unified) + try: + from pecos_rslib_exp import noise_characterization + + _json_str, dem_raw, dem_decomp = noise_characterization(abstract_tc, **noise_params) + if dem_raw.strip(): + results.append(("noise_char", dem_raw, dem_decomp)) + except Exception as e: + print(f" WARN: noise_characterization failed: {e}") + + # 4. perturbative_dem (EEG, forward) + try: + from pecos_rslib_exp import perturbative_dem + + dem_raw, dem_decomp = perturbative_dem(abstract_tc, **noise_params) + if dem_raw.strip(): + results.append(("perturbative", dem_raw, dem_decomp)) + except Exception as e: + print(f" WARN: perturbative_dem failed: {e}") + + return results + + +def _sample_from_sim(tc, noise_params, shots, seed, backend="statevec"): + """Sample using sim_neo (captures actual noise including coherent). + + backend: "statevec" (exact, small circuits), + "stabilizer" (exact for depol, fast — no coherent idle_rz), + "stab_mps" (handles coherent noise, any distance, approximate). + """ + import json + from pecos_rslib_exp import depolarizing, sim_neo, stabilizer, statevec, stab_mps + + p1 = noise_params.get("p1", 0.0) + p2 = noise_params.get("p2", 0.0) + p_meas = noise_params.get("p_meas", 0.0) + p_prep = noise_params.get("p_prep", 0.0) + irz = noise_params.get("idle_rz", 0.0) + + noise = depolarizing().p1(p1).p2(p2).p_meas(p_meas).p_prep(p_prep) + if irz > 0: + noise = noise.idle_rz(irz) + + if backend == "stabilizer": + quantum_backend = stabilizer() + elif backend == "stab_mps": + quantum_backend = stab_mps() + else: + quantum_backend = statevec() + + results = sim_neo(tc).quantum(quantum_backend).noise(noise).shots(shots).seed(seed).run() + + det_json = json.loads(tc.get_meta("detectors")) + obs_json = json.loads(tc.get_meta("observables")) + num_meas = int(tc.get_meta("num_measurements")) + + return sim_results_to_sample_batch(results, det_json, obs_json, num_meas) + + +def strip_logical_observable_lines(dem_str: str) -> str: + """Remove logical_observable lines that some decoders choke on.""" + return "\n".join( + line for line in dem_str.split("\n") if not line.startswith("logical_observable") + ) + + +def run_comparison( + *, + distances: list[int], + noise_configs: list[tuple[str, dict]], + decoders: list[str], + basis: str, + shots: int, + seed: int, + sample_backend: str, +): + """Run the full DEM method x decoder comparison.""" + all_results = [] + + for distance in distances: + num_rounds = 2 * distance + for noise_label, noise_params in noise_configs: + print(f"\n{'='*72}") + print(f"d={distance} {basis}-basis, {num_rounds} rounds, {noise_label}") + print(f" sample_backend={sample_backend}") + print(f"{'='*72}") + + # Build both abstract and traced circuits + t0 = time.perf_counter() + patch, abstract_tc, traced_tc = build_tick_circuits(distance, num_rounds, basis) + t_circuit = time.perf_counter() - t0 + print(f" Circuits built in {t_circuit:.2f}s") + + sampler_params = { + k: v for k, v in noise_params.items() if k in ("p1", "p2", "p_meas", "p_prep") + } + idle_rz = noise_params.get("idle_rz", 0.0) + + # Generate samples + t0 = time.perf_counter() + if sample_backend in ("statevec", "stabilizer", "stab_mps"): + # Simulator-based sampling + batch = _sample_from_sim( + abstract_tc, noise_params, shots, seed, + backend=sample_backend, + ) + else: + # DemSampler: fast, stochastic-only sampling + from pecos_rslib.qec import DemSampler + sampler = DemSampler.from_circuit( + traced_tc, **sampler_params, idle_rz=idle_rz if idle_rz > 0 else None, + ) + batch = sampler.generate_samples(shots, seed=seed) + t_sample = time.perf_counter() - t0 + print(f" Sampled {shots} shots in {t_sample:.2f}s") + + # Generate DEMs from all methods + t0 = time.perf_counter() + dems = generate_dems(abstract_tc, traced_tc, patch, num_rounds, noise_params, basis) + t_dems = time.perf_counter() - t0 + print(f" Generated {len(dems)} DEMs in {t_dems:.2f}s") + for name, dem_str, _decomp in dems: + n_lines = len([l for l in dem_str.strip().split("\n") if l.strip()]) + print(f" {name}: {n_lines} lines") + + # Build column headers: for raw-capable decoders, show both raw and decomposed + columns = [] + for dec in decoders: + if _decoder_requires_graphlike(dec): + columns.append((dec, "decomp")) + else: + columns.append((dec, "raw")) + columns.append((dec, "decomp")) + + # Print header + print(f"\n {'DEM Method':<22s}", end="") + for dec, dem_type in columns: + label = f"{dec}({dem_type[0]})" if dem_type == "raw" else f"{dec}(d)" + print(f" | {label:>16s}", end="") + print() + print(f" {'-'*22}", end="") + for _ in columns: + print(f" | {'-'*16}", end="") + print() + + for dem_name, dem_raw, dem_decomp in dems: + dem_raw_clean = strip_logical_observable_lines(dem_raw) + dem_decomp_clean = ( + strip_logical_observable_lines(dem_decomp) if dem_decomp else None + ) + print(f" {dem_name:<22s}", end="", flush=True) + + for decoder, dem_type in columns: + base = decoder.split(":")[0] + + if dem_type == "decomp" and dem_decomp_clean is None: + # No decomposed DEM available for this method + print(f" | {'N/A':>16s}", end="") + continue + + dem = dem_raw_clean if dem_type == "raw" else dem_decomp_clean + + try: + if base in SLOW_DECODERS: + stats = batch.decode_stats_parallel(dem, decoder) + else: + stats = batch.decode_stats(dem, decoder) + ler = stats.logical_error_rate + print(f" | {ler:>16.4f}", end="") + all_results.append({ + "distance": distance, + "noise": noise_label, + "dem_method": dem_name, + "decoder": decoder, + "dem_type": dem_type, + "num_shots": shots, + "num_errors": stats.num_errors, + "ler": ler, + "decode_s": stats.total_seconds, + }) + except Exception: + # Decoder can't handle this DEM (e.g., hyperedges in graphlike DEM) + print(f" | {'N/A':>16s}", end="") + + print() + + return all_results + + +def main(): + parser = argparse.ArgumentParser( + description="DEM method x decoder LER comparison on traced_qis circuits", + ) + parser.add_argument("--distances", type=int, nargs="+", default=[3, 5]) + parser.add_argument("--shots", type=int, default=10_000) + parser.add_argument("--basis", default="Z") + parser.add_argument("--seed", type=int, default=42) + parser.add_argument( + "--decoders", + nargs="+", + default=["pymatching", "fusion_blossom", "tesseract"], + ) + parser.add_argument("--p2", type=float, default=0.005) + parser.add_argument("--idle-rz", type=float, default=0.05) + parser.add_argument( + "--noise", + nargs="+", + default=["depol", "depol+irz"], + choices=["depol", "depol+irz"], + ) + parser.add_argument( + "--sample-backend", + default="native", + choices=["native", "statevec", "stabilizer", "stab_mps"], + help="'native' uses DemSampler (fast, stochastic). " + "'statevec' uses exact state vector sim (slow, captures coherent). " + "'stabilizer' uses stabilizer sim (fast, exact for depolarizing). " + "'stab_mps' uses tensor network sim (handles coherent, any distance).", + ) + args = parser.parse_args() + + p2 = args.p2 + noise_configs = [] + if "depol" in args.noise: + noise_configs.append(( + f"depol(p2={p2})", + {"p1": p2 / 10, "p2": p2, "p_meas": p2, "p_prep": p2, "idle_rz": 0.0}, + )) + if "depol+irz" in args.noise: + noise_configs.append(( + f"depol+irz(p2={p2},irz={args.idle_rz})", + {"p1": p2 / 10, "p2": p2, "p_meas": p2, "p_prep": p2, "idle_rz": args.idle_rz}, + )) + + results = run_comparison( + distances=args.distances, + noise_configs=noise_configs, + decoders=args.decoders, + basis=args.basis, + shots=args.shots, + seed=args.seed, + sample_backend=args.sample_backend, + ) + + print(f"\n\nTotal results: {len(results)}") + + +if __name__ == "__main__": + main() diff --git a/examples/surface/dem_tutorial.py b/examples/surface/dem_tutorial.py new file mode 100644 index 000000000..1ea342cdf --- /dev/null +++ b/examples/surface/dem_tutorial.py @@ -0,0 +1,131 @@ +"""DEM generation tutorial: build circuit, inspect DEM, sample, validate. + +Demonstrates the full PECOS DEM pipeline using a d=3 surface code. + +Usage: + uv run python examples/surface/dem_tutorial.py +""" + +from __future__ import annotations + +import json +import sys +from pathlib import Path + +sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "python" / "quantum-pecos" / "src")) + +from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch +from pecos_rslib.qec import DemSampler, DetectorErrorModel, DemBuilder, DagFaultAnalyzer +from pecos_rslib_exp import sim_neo, stabilizer, depolarizing + + +def main(): + # ================================================================ + # 1. Build a surface code circuit + # ================================================================ + distance = 3 + patch = SurfacePatch.create(distance=distance) + b = LogicalCircuitBuilder() + b.add_patch(patch, "Q0") + b.add_memory("Q0", rounds=distance, basis="Z") + tc = b.to_tick_circuit() + + print(f"Surface code d={distance}, {tc.num_ticks()} ticks") + print(f" {int(tc.get_meta('num_measurements'))} measurements, " + f"{len(json.loads(tc.get_meta('detectors')))} detectors") + + # ================================================================ + # 2. Inspect measurement IDs on gates + # ================================================================ + # Each MZ gate carries a MeasId — a stable identity for that + # measurement result. These persist through all transformations. + dag = tc.to_dag_circuit() + + print("\nMeasurement gates (first 5):") + shown = 0 + for node_id in dag.nodes(): + gate = dag.gate(node_id) + if gate and gate.gate_type.name == "MZ" and shown < 5: + print(f" node={node_id}: MZ qubit={list(gate.qubits)} meas_ids={gate.meas_ids}") + shown += 1 + + # ================================================================ + # 3. Inspect detector definitions + # ================================================================ + # Detectors reference measurements by both: + # - "records": negative offsets (Stim compatibility) + # - "meas_ids": stable MeasId values (preferred) + dets = json.loads(tc.get_meta("detectors")) + print(f"\nDetector definitions (first 3 of {len(dets)}):") + for det in dets[:3]: + print(f" D{det['id']}: meas_ids={det['meas_ids']} records={det['records']}") + + # ================================================================ + # 4. Build and inspect the DEM (one line) + # ================================================================ + p = 0.005 + dem = DetectorErrorModel.from_circuit(tc, p1=p, p2=p, p_meas=p, p_prep=p) + print(f"\nDetectorErrorModel: {dem.num_detectors} detectors, " + f"{dem.num_observables} observables") + + dem_str = dem.to_string() + error_lines = [l for l in dem_str.split("\n") if l.startswith("error(")] + print(f" {len(error_lines)} DEM events") + print(" First 3 events:") + for line in error_lines[:3]: + print(f" {line}") + + # ================================================================ + # 5. Sample from the DEM (one line) + # ================================================================ + shots = 100_000 + sampler = DemSampler.from_circuit(tc, p1=p, p2=p, p_meas=p, p_prep=p) + batch = sampler.generate_samples(num_shots=shots, seed=42) + + # Compute per-detector firing rates from DEM sampling + num_dets = len(dets) + dem_rates = [0.0] * num_dets + for i in range(shots): + syn = batch.get_syndrome(i) + for d in range(min(num_dets, len(syn))): + if syn[d]: + dem_rates[d] += 1.0 / shots + + # ================================================================ + # 6. Validate against stabilizer simulation (ground truth) + # ================================================================ + noise = depolarizing().p1(p).p2(p).p_meas(p).p_prep(p) + results = sim_neo(tc).quantum(stabilizer()).noise(noise).shots(shots).seed(42).run() + + num_meas = int(tc.get_meta("num_measurements")) + sim_rates = [0.0] * num_dets + for r in results: + meas = list(r) + for i, det in enumerate(dets): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + sim_rates[i] += 1.0 / shots + + # ================================================================ + # 7. Compare + # ================================================================ + print(f"\nPer-detector rates (p={p}, {shots} shots):") + print(f" {'Det':>4} {'DEM':>10} {'Stabilizer':>10} {'Ratio':>7}") + max_rel = 0 + for d in range(num_dets): + if sim_rates[d] > 0.003: + ratio = dem_rates[d] / sim_rates[d] + max_rel = max(max_rel, abs(1 - ratio)) + print(f" D{d:>2} {dem_rates[d]:>10.5f} {sim_rates[d]:>10.5f} {ratio:>7.3f}") + + status = "PASS" if max_rel < 0.15 else f"FAIL (max_rel={max_rel*100:.0f}%)" + print(f"\nValidation: {status}") + print(f" Max relative error: {max_rel*100:.1f}% (threshold: 15% for {shots} shots)") + + +if __name__ == "__main__": + main() diff --git a/examples/surface/dem_vs_stabilizer.py b/examples/surface/dem_vs_stabilizer.py new file mode 100644 index 000000000..b34f3911d --- /dev/null +++ b/examples/surface/dem_vs_stabilizer.py @@ -0,0 +1,164 @@ +r"""Compare non-EEG DEM detection rates against stabilizer() ground truth. + +Tests per-detector firing rates from: + 1. DemBuilder analytical marginals (sum of DEM event probabilities) + 2. DemSampler.from_circuit sampled rates + 3. stabilizer() simulation (SparseStab ground truth) + +Pure depolarizing noise only (no coherent idle_rz). + +Example: + uv run python examples/surface/dem_vs_stabilizer.py + uv run python examples/surface/dem_vs_stabilizer.py -d 2 3 --p 0.005 +""" + +from __future__ import annotations + +import argparse +import json +import math +import sys +import time +from pathlib import Path + +sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "python" / "quantum-pecos" / "src")) + + +def run_comparison(*, distance, rounds, basis, p, shots, seed): + from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch + from pecos_rslib.qec import DemBuilder, DagFaultAnalyzer, DemSampler + from pecos_rslib_exp import sim_neo, stabilizer, depolarizing + + patch = SurfacePatch.create(distance=distance) + b = LogicalCircuitBuilder() + b.add_patch(patch, "Q0") + b.add_memory("Q0", rounds=rounds, basis=basis) + tc = b.to_tick_circuit() + dag = tc.to_dag_circuit() + + det_json = json.loads(tc.get_meta("detectors")) + num_meas = int(tc.get_meta("num_measurements")) + num_dets = len(det_json) + + print(f"\n{'='*70}") + print(f"d={distance} {basis}-basis, {rounds} rounds, {num_dets} dets, p={p}") + print(f"{'='*70}") + + # 1. DemBuilder analytical marginals + analyzer = DagFaultAnalyzer(dag) + influence = analyzer.build_influence_map() + dem_obj = ( + DemBuilder(influence) + .with_noise(p1=p, p2=p, p_meas=p, p_prep=p) + .with_detectors_json(tc.get_meta("detectors")) + .with_observables_json(tc.get_meta("observables")) + .with_num_measurements(num_meas) + .build() + ) + dem_str = dem_obj.to_string() + analytical = [0.0] * num_dets + for line in dem_str.strip().split("\n"): + if line.startswith("error("): + prob = float(line.split("(")[1].split(")")[0]) + for x in line.split(): + if x.startswith("D"): + d_id = int(x[1:]) + if d_id < num_dets: + analytical[d_id] += prob + + # 2. DemSampler.from_circuit + t0 = time.perf_counter() + sampler_fc = DemSampler.from_circuit(dag, p1=p, p2=p, p_meas=p, p_prep=p) + batch_fc = sampler_fc.generate_samples(num_shots=shots, seed=seed) + dem_fc = [0.0] * num_dets + for i in range(shots): + syn = batch_fc.get_syndrome(i) + for dd in range(min(num_dets, len(syn))): + if syn[dd]: + dem_fc[dd] += 1.0 / shots + fc_time = time.perf_counter() - t0 + + # 3. stabilizer() ground truth + t0 = time.perf_counter() + noise = depolarizing().p1(p).p2(p).p_meas(p).p_prep(p) + results = sim_neo(tc).quantum(stabilizer()).noise(noise).shots(shots).seed(seed).run() + sim = [0.0] * num_dets + for r in results: + meas = list(r) + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + sim[i] += 1.0 / shots + sim_time = time.perf_counter() - t0 + + print(f" DEM sample: {fc_time:.2f}s, Stabilizer: {sim_time:.2f}s ({shots} shots)") + print( + f" {'Det':>4} {'Analytical':>11} {'FromCirc':>10} {'Stabiliz':>10}" + f" {'SV_se':>8} {'A/Sim':>7} {'FC/Sim':>7}" + ) + + max_a_err = 0.0 + max_fc_err = 0.0 + flagged = 0 + for dd in range(num_dets): + sv_r = sim[dd] + se = math.sqrt(sv_r * (1 - sv_r) / shots) if sv_r > 0 else 0 + + if sv_r > 0.002: + ra = analytical[dd] / sv_r + rf = dem_fc[dd] / sv_r + max_a_err = max(max_a_err, abs(1 - ra)) + max_fc_err = max(max_fc_err, abs(1 - rf)) + else: + ra = float("nan") + rf = float("nan") + + flag = "" + if sv_r > 0.002 and (abs(1 - ra) > 0.15 or abs(1 - rf) > 0.15): + flag = " ***" + flagged += 1 + + print( + f" D{dd:>2} {analytical[dd]:>11.6f} {dem_fc[dd]:>10.6f} {sv_r:>10.6f}" + f" {se:>8.5f} {ra:>7.3f} {rf:>7.3f}{flag}" + ) + + print( + f" Max deviation: Analytical={max_a_err*100:.1f}%," + f" FromCircuit={max_fc_err*100:.1f}%, flagged={flagged}" + ) + + +def main(): + parser = argparse.ArgumentParser( + description=__doc__, + formatter_class=argparse.RawDescriptionHelpFormatter, + ) + parser.add_argument("--distance", "-d", type=int, nargs="+", default=[2, 3]) + parser.add_argument("--rounds", type=int, default=None) + parser.add_argument("--basis", choices=["X", "Z"], nargs="+", default=["X", "Z"]) + parser.add_argument("--p", type=float, nargs="+", default=[0.005]) + parser.add_argument("--shots", type=int, default=10000) + parser.add_argument("--seed", type=int, default=42) + args = parser.parse_args() + + for dist in args.distance: + for basis in args.basis: + for p_val in args.p: + rds = args.rounds if args.rounds is not None else dist + run_comparison( + distance=dist, + rounds=rds, + basis=basis, + p=p_val, + shots=args.shots, + seed=args.seed, + ) + + +if __name__ == "__main__": + main() diff --git a/examples/surface/eeg_formula_comparison.py b/examples/surface/eeg_formula_comparison.py new file mode 100644 index 000000000..9dfdcd754 --- /dev/null +++ b/examples/surface/eeg_formula_comparison.py @@ -0,0 +1,210 @@ +r"""Compare all forward EEG formula variants against backward Heisenberg. + +Tests 6 forward EEG configurations: + 1. Taylor + BCH1 (default) + 2. SinSquared + BCH1 + 3. ExactCommuting + BCH1 + 4. Taylor + BCH2 + 5. SinSquared + BCH2 + 6. ExactCommuting + BCH2 + +Against: + 7. Backward Heisenberg (exact) + 8. StateVec simulation (ground truth, optional) + +Example: + uv run python examples/surface/eeg_formula_comparison.py + uv run python examples/surface/eeg_formula_comparison.py -d 3 --theta 0.05 --shots 50000 + uv run python examples/surface/eeg_formula_comparison.py -d 2 3 --no-statevec +""" + +from __future__ import annotations + +import argparse +import json +import math +import sys +import time +from pathlib import Path + +sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "python" / "quantum-pecos" / "src")) + +CONFIGS = [ + ("Taylor", "taylor", 1), + ("SinSq", "sin_squared", 1), + ("ExCom", "exact_commuting", 1), + ("ExSubset", "exact_subset", 1), +] + + +def marginals_from_events(events, num_dets): + rates = [0.0] * num_dets + for prob, det_ids, _obs_ids in events: + for d in det_ids: + if d < num_dets: + rates[d] += prob + return rates + + +def run(*, distance, rounds, basis, theta_values, shots, seed, run_statevec): + from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch + from pecos_rslib_exp import perturbative_dem_events, exact_detection_rates, eeg_per_detector + + patch = SurfacePatch.create(distance=distance) + b = LogicalCircuitBuilder() + b.add_patch(patch, "Q0") + b.add_memory("Q0", rounds=rounds, basis=basis) + tc = b.to_tick_circuit() + + det_json = json.loads(tc.get_meta("detectors")) + num_meas = int(tc.get_meta("num_measurements")) + num_dets = len(det_json) + + print(f"\n{'='*80}") + print(f"d={distance} {basis}-basis memory, {rounds} rounds, {num_dets} detectors") + print(f"{'='*80}") + + for theta in theta_values: + print(f"\ntheta = {theta:.4f}") + + # Forward EEG: all 6 configs + fwd_marginals = {} + for name, h_formula, bch in CONFIGS: + t0 = time.perf_counter() + events = perturbative_dem_events(tc, idle_rz=theta, h_formula=h_formula, bch_order=bch) + dt = time.perf_counter() - t0 + fwd_marginals[name] = (marginals_from_events(events, num_dets), dt) + + # Per-detector computation (cross-event beta) + per_det_marginals = {} + for name, h_formula, _ in [("PD-Taylor", "taylor", 0), ("PD-SinSq", "sin_squared", 0), ("PD-ExCom", "exact_commuting", 0)]: + t0 = time.perf_counter() + pd_results = eeg_per_detector(tc, idle_rz=theta, h_formula=h_formula) + dt = time.perf_counter() - t0 + rates = [0.0] * num_dets + for det_id, prob in pd_results: + if det_id < num_dets: + rates[det_id] = prob + per_det_marginals[name] = (rates, dt) + + # Backward Heisenberg (exact) + t0 = time.perf_counter() + heis_results = exact_detection_rates(tc, idle_rz=theta) + heis_time = time.perf_counter() - t0 + heis = [0.0] * num_dets + for det_id, prob in heis_results: + if det_id < num_dets: + heis[det_id] = prob + + # StateVec (optional ground truth) + sv_rate = None + if run_statevec: + from pecos_rslib_exp import sim_neo, statevec, depolarizing + t0 = time.perf_counter() + noise = depolarizing().idle_rz(theta) + results = sim_neo(tc).quantum(statevec()).noise(noise).shots(shots).seed(seed).run() + sv_time = time.perf_counter() - t0 + + sv_det_count = [0] * num_dets + for r in results: + meas = list(r) + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + sv_det_count[i] += 1 + sv_rate = [c / shots for c in sv_det_count] + + # Summary table: max relative error vs Heisenberg for each config + print(f"\n {'Config':<14} {'Time':>8} {'MaxRelErr':>10} {'MeanRelErr':>11} {'MaxAbsErr':>10}") + print(f" {'-'*14} {'-'*8} {'-'*10} {'-'*11} {'-'*10}") + + all_configs = [(name, fwd_marginals[name]) for name, _, _ in CONFIGS] + all_configs += [(name, per_det_marginals[name]) for name in ["PD-Taylor", "PD-SinSq", "PD-ExCom"]] + + for name, (rates, dt) in all_configs: + max_rel = 0.0 + sum_rel = 0.0 + max_abs = 0.0 + count = 0 + for d in range(num_dets): + if heis[d] > 1e-6: + rel = abs(rates[d] - heis[d]) / heis[d] + max_rel = max(max_rel, rel) + sum_rel += rel + count += 1 + max_abs = max(max_abs, abs(rates[d] - heis[d])) + mean_rel = sum_rel / count if count > 0 else 0 + print(f" {name:<14} {dt*1000:>7.1f}ms {max_rel*100:>9.1f}% {mean_rel*100:>10.1f}% {max_abs:>10.6f}") + + print(f" {'Heisenberg':<14} {heis_time*1000:>7.1f}ms {'(exact)':>10}") + + if sv_rate is not None: + # Also compare Heisenberg vs StateVec + max_rel_h = 0.0 + for d in range(num_dets): + if sv_rate[d] > 0.01: + max_rel_h = max(max_rel_h, abs(heis[d] - sv_rate[d]) / sv_rate[d]) + print(f" {'StateVec':<14} {sv_time:>6.1f}s H/SV max err: {max_rel_h*100:.1f}%") + + # Per-detector detail (compact — only show non-zero detectors, skip redundant DEM configs) + if num_dets <= 40: + # Show: Heisenberg, Taylor (DEM), PD-Taylor, PD-ExCom, SV + show_configs = [ + ("Taylor", lambda: fwd_marginals["Taylor"]), + ("ExSubset", lambda: fwd_marginals["ExSubset"]), + ("PD-Tayl", lambda: per_det_marginals["PD-Taylor"]), + ] + cols = ["Det", "Heisen"] + [n for n, _ in show_configs] + if sv_rate is not None: + cols.append("SV") + header = f" {cols[0]:>4} {cols[1]:>10}" + for c in cols[2:]: + header += f" {c:>10}" + print(f"\n{header}") + + for d in range(num_dets): + if heis[d] < 1e-8 and all(fn()[0][d] < 1e-8 for _, fn in show_configs): + continue + line = f" D{d:>2} {heis[d]:>10.6f}" + for _, fn in show_configs: + rates, _ = fn() + line += f" {rates[d]:>10.6f}" + if sv_rate is not None: + line += f" {sv_rate[d]:>10.6f}" + print(line) + + +def main(): + parser = argparse.ArgumentParser( + description=__doc__, + formatter_class=argparse.RawDescriptionHelpFormatter, + ) + parser.add_argument("--distance", "-d", type=int, nargs="+", default=[2, 3]) + parser.add_argument("--rounds", type=int, default=None) + parser.add_argument("--basis", choices=["X", "Z"], nargs="+", default=["Z"]) + parser.add_argument("--theta", type=float, nargs="+", default=[0.01, 0.05, 0.1]) + parser.add_argument("--shots", type=int, default=50000) + parser.add_argument("--seed", type=int, default=42) + parser.add_argument("--no-statevec", action="store_true") + args = parser.parse_args() + + for dist in args.distance: + for basis in args.basis: + rds = args.rounds if args.rounds is not None else dist + run( + distance=dist, + rounds=rds, + basis=basis, + theta_values=args.theta, + shots=args.shots, + seed=args.seed, + run_statevec=not args.no_statevec, + ) + + +if __name__ == "__main__": + main() diff --git a/examples/surface/eeg_vs_statevec.py b/examples/surface/eeg_vs_statevec.py new file mode 100644 index 000000000..340eceae0 --- /dev/null +++ b/examples/surface/eeg_vs_statevec.py @@ -0,0 +1,202 @@ +r"""Compare EEG analytical DEM vs StateVec empirical detection rates. + +Three approaches compared: + 1. Forward EEG (perturbative Taylor/SinSquared formula) — fast, approximate + 2. Backward Heisenberg (exact coherent + stochastic) — slower build, exact + 3. StateVec simulation (ground truth) — slow, limited by qubit count + +Both EEG approaches produce Stim-format DEM strings that can be sampled +at ~15M shots/sec via DemSampler.from_dem_string(). + +Example: + uv run python examples/surface/eeg_vs_statevec.py + uv run python examples/surface/eeg_vs_statevec.py --distance 3 --basis X --shots 20000 + uv run python examples/surface/eeg_vs_statevec.py --distance 2 --basis Z --shots 50000 + uv run python examples/surface/eeg_vs_statevec.py --distance 5 --basis Z --dem-sample +""" + +from __future__ import annotations + +import argparse +import json +import math +import sys +import time +from pathlib import Path + +sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "python" / "quantum-pecos" / "src")) + + +def run_comparison( + *, + distance: int, + rounds: int, + basis: str, + theta_values: list[float], + shots: int, + seed: int, + dem_sample: bool, +): + from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch + from pecos_rslib_exp import perturbative_dem, perturbative_dem_events, exact_detection_rates, sim_neo, statevec, depolarizing + + patch = SurfacePatch.create(distance=distance) + b = LogicalCircuitBuilder() + b.add_patch(patch, "Q0") + b.add_memory("Q0", rounds=rounds, basis=basis) + tc = b.to_tick_circuit() + + det_json = json.loads(tc.get_meta("detectors")) + num_meas = int(tc.get_meta("num_measurements")) + num_dets = len(det_json) + + print(f"\n{'='*70}") + print(f"d={distance} {basis}-basis memory, {rounds} rounds, {num_dets} detectors, {num_meas} measurements") + print(f"{'='*70}") + + for theta in theta_values: + print(f"\ntheta = {theta:.4f}") + + # --- Forward EEG DEM (Taylor) --- + t0 = time.perf_counter() + eeg_events = perturbative_dem_events(tc, idle_rz=theta, h_formula="taylor") + eeg_time = time.perf_counter() - t0 + + eeg_taylor = [0.0] * num_dets + for prob, det_ids, _obs_ids in eeg_events: + for d in det_ids: + if d < num_dets: + eeg_taylor[d] += prob + + # --- Heisenberg backward propagation --- + t0 = time.perf_counter() + heis_results = exact_detection_rates(tc, idle_rz=theta) + heis_time = time.perf_counter() - t0 + heis = [0.0] * num_dets + for det_id, prob in heis_results: + if det_id < num_dets: + heis[det_id] = prob + + # --- DEM sampling path (two-stage: build DEM once, sample fast) --- + if dem_sample: + from pecos_rslib.qec import DemSampler + + # Forward EEG DEM → sampler + t0 = time.perf_counter() + dem_taylor_str = perturbative_dem(tc, idle_rz=theta) + sampler_taylor = DemSampler.from_dem_string(dem_taylor_str) + batch_taylor = sampler_taylor.generate_samples(num_shots=shots, seed=seed) + taylor_sample_time = time.perf_counter() - t0 + + # Heisenberg DEM → sampler + t0 = time.perf_counter() + dem_heis_str = coherent_dem(tc, idle_rz=theta) + sampler_heis = DemSampler.from_dem_string(dem_heis_str) + batch_heis = sampler_heis.generate_samples(num_shots=shots, seed=seed) + heis_sample_time = time.perf_counter() - t0 + + # Compute per-detector rates from DEM samples + taylor_dem_rates = [0.0] * num_dets + heis_dem_rates = [0.0] * num_dets + for i in range(shots): + syn_t = batch_taylor.get_syndrome(i) + syn_h = batch_heis.get_syndrome(i) + for d in range(min(num_dets, len(syn_t))): + if syn_t[d]: + taylor_dem_rates[d] += 1.0 / shots + if syn_h[d]: + heis_dem_rates[d] += 1.0 / shots + else: + taylor_dem_rates = None + heis_dem_rates = None + taylor_sample_time = 0 + heis_sample_time = 0 + + # --- StateVec simulation (ground truth) --- + t0 = time.perf_counter() + noise = depolarizing().idle_rz(theta) + results = sim_neo(tc).quantum(statevec()).noise(noise).shots(shots).seed(seed).run() + sv_time = time.perf_counter() - t0 + + sv_det_count = [0] * num_dets + for r in results: + meas = list(r) + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + sv_det_count[i] += 1 + + sv_det_rate = [c / shots for c in sv_det_count] + + # --- Compare --- + print(f" EEG: {eeg_time*1000:.1f}ms, Heisenberg: {heis_time*1000:.1f}ms, StateVec: {sv_time:.1f}s ({shots} shots)") + if dem_sample: + print(f" DEM sample: Taylor {taylor_sample_time:.2f}s, Heisenberg {heis_sample_time:.2f}s ({shots} shots)") + + if dem_sample: + print(f" {'Det':>4} {'Taylor':>10} {'Heisen':>10} {'T(DEM)':>10} {'H(DEM)':>10} {'StateVec':>10} {'SV_se':>8} {'T/SV':>7} {'H/SV':>7}") + else: + print(f" {'Det':>4} {'Taylor':>10} {'Heisen':>10} {'StateVec':>10} {'SV_se':>8} {'T/SV':>7} {'H/SV':>7}") + + max_rel_taylor = 0.0 + max_rel_heis = 0.0 + for d in range(num_dets): + tp = eeg_taylor[d] + hp = heis[d] + sv_r = sv_det_rate[d] + sv_se = math.sqrt(sv_r * (1 - sv_r) / shots) if shots > 0 else 0 + + if sv_r > 0.0001: + t_ratio = tp / sv_r + h_ratio = hp / sv_r + max_rel_taylor = max(max_rel_taylor, abs(tp - sv_r) / sv_r) + max_rel_heis = max(max_rel_heis, abs(hp - sv_r) / sv_r) + else: + t_ratio = float("nan") + h_ratio = float("nan") + + if dem_sample: + td = taylor_dem_rates[d] if taylor_dem_rates else 0 + hd = heis_dem_rates[d] if heis_dem_rates else 0 + print(f" D{d:>3} {tp:>10.6f} {hp:>10.6f} {td:>10.6f} {hd:>10.6f} {sv_r:>10.6f} {sv_se:>8.6f} {t_ratio:>7.3f} {h_ratio:>7.3f}") + else: + print(f" D{d:>3} {tp:>10.6f} {hp:>10.6f} {sv_r:>10.6f} {sv_se:>8.6f} {t_ratio:>7.3f} {h_ratio:>7.3f}") + + print(f" Max rel err: Taylor={max_rel_taylor*100:.1f}%, Heisenberg={max_rel_heis*100:.1f}%") + + +def main(): + parser = argparse.ArgumentParser( + description=__doc__, + formatter_class=argparse.RawDescriptionHelpFormatter, + ) + parser.add_argument("--distance", "-d", type=int, nargs="+", default=[2, 3]) + parser.add_argument("--rounds", type=int, default=None) + parser.add_argument("--basis", choices=["X", "Z"], nargs="+", default=["X", "Z"]) + parser.add_argument("--theta", type=float, nargs="+", default=[0.01, 0.03, 0.05, 0.1]) + parser.add_argument("--shots", type=int, default=20000) + parser.add_argument("--seed", type=int, default=42) + parser.add_argument("--dem-sample", action="store_true", + help="Also sample from both DEMs and compare rates") + args = parser.parse_args() + + for dist in args.distance: + for basis in args.basis: + rds = args.rounds if args.rounds is not None else dist + run_comparison( + distance=dist, + rounds=rds, + basis=basis, + theta_values=args.theta, + shots=args.shots, + seed=args.seed, + dem_sample=args.dem_sample, + ) + + +if __name__ == "__main__": + main() diff --git a/examples/surface/generate_data.py b/examples/surface/generate_data.py new file mode 100644 index 000000000..1eb99df7b --- /dev/null +++ b/examples/surface/generate_data.py @@ -0,0 +1,346 @@ +r"""Generate decoder performance data for surface code memory experiments. + +Samples detection events once per (distance, error_rate, rounds) point, +then decodes with each requested decoder. Writes a JSON shard that can +be fed to ``analyze_data.py`` and ``build_report.py``. + +Example: + uv run python examples/surface/generate_data.py \\ + --distances 3 5 --error-rates 0.004 0.008 \\ + --decoders pymatching mwpf tesseract bp_osd \\ + --shots 5000 + + uv run python examples/surface/generate_data.py \\ + --distances 3 5 7 \\ + --error-rates 0.002 0.004 0.006 0.008 \\ + --decoders pymatching mwpf tesseract \\ + --duration-multipliers 2 2.5 3 \\ + --shots 2000 --output-dir results/ +""" + +from __future__ import annotations + +import argparse +import json +import time +from dataclasses import asdict, dataclass, field +from pathlib import Path +from typing import TYPE_CHECKING + +if TYPE_CHECKING: + from pecos.qec.surface import NoiseModel + +# -- Data model --------------------------------------------------------------- + + +@dataclass +class DecoderStats: + """Decode statistics for one decoder on one set of samples.""" + + decoder: str + num_errors: int + logical_error_rate: float + total_decode_seconds: float + per_shot_mean: float + per_shot_median: float + per_shot_p99: float + per_shot_max: float + # 21 quantiles at [0%, 5%, 10%, ..., 95%, 100%] for violin plots + quantiles: list[float] = field(default_factory=list) + + +@dataclass +class DataPoint: + """Raw data for one (distance, basis, p, rounds, decoder-set) cell.""" + + distance: int + basis: str + physical_error_rate: float + num_rounds: int + num_shots: int + sample_seconds: float + decoder_stats: list[DecoderStats] = field(default_factory=list) + + +@dataclass +class DataShard: + """One complete data-generation run. Serialised to JSON.""" + + config: dict + points: list[DataPoint] = field(default_factory=list) + total_seconds: float = 0.0 + + +# -- DEM sets for different decoder families ---------------------------------- + +# MWPM decoders need decomposed (graphlike) DEMs. +_MWPM_DECODERS = { + "pymatching", + "pymatching_uncorrelated", + "fusion_blossom", + "fusion_blossom_serial", + "fusion_blossom_parallel", +} + +# Slow decoders benefit from parallel decode. +_SLOW_DECODERS = {"tesseract", "mwpf", "bp_osd", "relay_bp"} + + +def _decoder_base_name(name: str) -> str: + """Strip config suffix: 'mwpf:c=30' -> 'mwpf'.""" + return name.split(":", maxsplit=1)[0] + + +# -- Sampler + DEM construction ----------------------------------------------- + + +def _build_sampler( + distance: int, + num_rounds: int, + noise: NoiseModel, + basis: str, + circuit_source: str, +) -> tuple: + """Build native sampler and return (sampler, dem_decomposed, dem_full).""" + from pecos.qec.surface import SurfacePatch, build_native_sampler + from pecos.qec.surface.decode import SurfaceDecoder, generate_circuit_level_dem_from_builder + + patch = SurfacePatch.create(distance=distance) + sampler = build_native_sampler( + patch, + num_rounds, + noise, + basis=basis, + circuit_source=circuit_source, + ) + + # Decomposed DEM for MWPM decoders + dec = SurfaceDecoder( + patch, + num_rounds=num_rounds, + noise=noise, + decoder_type="pymatching", + use_circuit_level_dem=True, + circuit_level_dem_mode="native_decomposed", + circuit_level_dem_source=circuit_source, + ) + dem_decomp = dec.get_dem(basis.upper(), circuit_level=True) + dem_decomp = "\n".join(line for line in dem_decomp.split("\n") if not line.startswith("logical_observable")) + + # Full DEM for non-MWPM decoders + dem_full = generate_circuit_level_dem_from_builder( + patch, + num_rounds, + noise, + basis=basis, + decompose_errors=False, + circuit_source=circuit_source, + ) + dem_full = "\n".join(line for line in dem_full.split("\n") if not line.startswith("logical_observable")) + + return sampler, dem_decomp, dem_full + + +# -- Main generation loop ----------------------------------------------------- + + +def generate( + *, + distances: list[int], + error_rates: list[float], + decoders: list[str], + basis: str, + shots: int, + seed: int, + circuit_source: str, + p1_scale: float, + p_meas_scale: float, + p_prep_scale: float, + duration_multipliers: list[float], +) -> DataShard: + """Run the full data generation and return a shard.""" + from pecos.qec.surface import NoiseModel + + config = { + "distances": distances, + "error_rates": error_rates, + "decoders": decoders, + "basis": basis.upper(), + "shots": shots, + "seed": seed, + "circuit_source": circuit_source, + "p1_scale": p1_scale, + "p_meas_scale": p_meas_scale, + "p_prep_scale": p_prep_scale, + "duration_multipliers": duration_multipliers, + } + + shard = DataShard(config=config) + t_start = time.perf_counter() + + # Compute distinct round counts per distance. + # For small d, multipliers may collide after truncation. + # Ensure at least len(duration_multipliers) distinct round counts + # by extending the range upward if needed. + rounds_per_d: dict[int, list[int]] = {} + for d in distances: + seen = set() + for mult in duration_multipliers: + seen.add(max(2, int(d * mult))) + # If we got fewer than requested, fill in consecutive integers from 2*d + target = len(duration_multipliers) + r_start = 2 * d + while len(seen) < target: + seen.add(r_start) + r_start += 1 + rounds_per_d[d] = sorted(seen) + + total_cells = sum(len(rounds_per_d[d]) for d in distances) * len(error_rates) + cell_idx = 0 + + for d in distances: + for p in error_rates: + noise = NoiseModel( + p1=p * p1_scale, + p2=p, + p_meas=p * p_meas_scale, + p_prep=p * p_prep_scale, + ) + + for num_rounds in rounds_per_d[d]: + cell_idx += 1 + print(f"[{cell_idx}/{total_cells}] d={d} p={p:.4g} r={num_rounds} ...") + + sampler, dem_decomp, dem_full = _build_sampler( + d, + num_rounds, + noise, + basis, + circuit_source, + ) + + # Sample once + t0 = time.perf_counter() + batch = sampler.sampler.generate_samples(shots, seed=seed + cell_idx) + sample_seconds = time.perf_counter() - t0 + + point = DataPoint( + distance=d, + basis=basis.upper(), + physical_error_rate=p, + num_rounds=num_rounds, + num_shots=shots, + sample_seconds=sample_seconds, + ) + + # Decode with each decoder + for decoder_name in decoders: + base = _decoder_base_name(decoder_name) + dem = dem_decomp if base in _MWPM_DECODERS else dem_full + + if base in _SLOW_DECODERS: + stats = batch.decode_stats_parallel(dem, decoder_name) + else: + stats = batch.decode_stats(dem, decoder_name) + + point.decoder_stats.append( + DecoderStats( + decoder=decoder_name, + num_errors=stats.num_errors, + logical_error_rate=stats.logical_error_rate, + total_decode_seconds=stats.total_seconds, + per_shot_mean=stats.per_shot_mean, + per_shot_median=stats.per_shot_median, + per_shot_p99=stats.per_shot_p99, + per_shot_max=stats.per_shot_max, + quantiles=list(stats.quantiles), + ), + ) + + print( + f" {decoder_name:20s}: {stats.num_errors:>4d}/{shots} " + f"LER={stats.logical_error_rate:.4f} " + f"median={stats.per_shot_median:.1e}s " + f"p99={stats.per_shot_p99:.1e}s", + ) + + shard.points.append(point) + + shard.total_seconds = time.perf_counter() - t_start + return shard + + +# -- CLI ---------------------------------------------------------------------- + + +def main() -> int: + """CLI entry point for data generation.""" + parser = argparse.ArgumentParser( + description=__doc__, + formatter_class=argparse.RawDescriptionHelpFormatter, + ) + parser.add_argument("--distances", nargs="+", type=int, default=[3, 5]) + parser.add_argument("--error-rates", nargs="+", type=float, default=[0.004, 0.006, 0.008]) + parser.add_argument( + "--decoders", + nargs="+", + default=["pymatching", "mwpf", "tesseract", "bp_osd"], + help="Decoders to run. Use 'mwpf:c=30,t=0.5' for config overrides.", + ) + parser.add_argument("--shots", type=int, default=1000) + parser.add_argument("--basis", default="Z") + parser.add_argument("--seed", type=int, default=42) + parser.add_argument("--circuit-source", default="traced_qis", choices=["traced_qis", "abstract"]) + parser.add_argument("--p1-scale", type=float, default=1.0 / 30.0) + parser.add_argument("--p-meas-scale", type=float, default=1.0 / 3.0) + parser.add_argument("--p-prep-scale", type=float, default=1.0 / 3.0) + parser.add_argument( + "--duration-multipliers", + nargs="+", + type=float, + default=[2.0], + help="Round count = distance * multiplier. Use multiple for threshold fitting.", + ) + parser.add_argument("--output-dir", type=str, default=None) + args = parser.parse_args() + + print("PECOS Data Generation") + print("=" * 40) + for k, v in vars(args).items(): + if k != "output_dir": + print(f" {k}: {v}") + print() + + shard = generate( + distances=sorted(args.distances), + error_rates=sorted(args.error_rates), + decoders=args.decoders, + basis=args.basis, + shots=args.shots, + seed=args.seed, + circuit_source=args.circuit_source, + p1_scale=args.p1_scale, + p_meas_scale=args.p_meas_scale, + p_prep_scale=args.p_prep_scale, + duration_multipliers=sorted(args.duration_multipliers), + ) + + print(f"\nTotal time: {shard.total_seconds:.1f}s") + + if args.output_dir: + out = Path(args.output_dir) + else: + import tempfile + + out = Path(tempfile.mkdtemp(prefix="pecos_data_")) + + out.mkdir(parents=True, exist_ok=True) + json_path = out / "data.json" + json_path.write_text(json.dumps(asdict(shard), indent=2)) + print(f"Wrote {json_path}") + + return 0 + + +if __name__ == "__main__": + raise SystemExit(main()) diff --git a/examples/surface/ml_lookup_decoder.py b/examples/surface/ml_lookup_decoder.py new file mode 100644 index 000000000..dba9fb64c --- /dev/null +++ b/examples/surface/ml_lookup_decoder.py @@ -0,0 +1,231 @@ +"""Maximum likelihood lookup decoder from simulation samples. + +For small codes (d=3: 256 syndromes), precomputes the optimal correction +for every possible syndrome by counting simulation outcomes. This is the +provably optimal decoder — useful as a gold standard for validation. + +Example: + uv run python examples/surface/ml_lookup_decoder.py +""" + +from __future__ import annotations + +import argparse +import sys +import time +from collections import defaultdict +from pathlib import Path + +sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "python" / "quantum-pecos" / "src")) + + +def build_lookup_table(batch, num_detectors: int) -> dict[tuple[int, ...], int]: + """Build a syndrome -> most_likely_observable_mask lookup table. + + For each unique syndrome observed in the batch, count how often each + observable mask occurs. The most common mask is the ML prediction. + """ + # syndrome (as tuple of fired detector indices) -> {obs_mask: count} + syndrome_counts: dict[tuple[int, ...], dict[int, int]] = defaultdict(lambda: defaultdict(int)) + + for i in range(batch.num_shots): + syn = batch.get_syndrome(i) + obs = batch.get_observable_mask(i) + + # Convert syndrome to tuple of fired detector indices + fired = tuple(d for d in range(min(num_detectors, len(syn))) if syn[d]) + syndrome_counts[fired][obs] += 1 + + # For each syndrome, pick the most likely observable mask + table: dict[tuple[int, ...], int] = {} + for syndrome, counts in syndrome_counts.items(): + best_mask = max(counts, key=counts.get) + table[syndrome] = best_mask + + return table + + +def decode_with_lookup(batch, table: dict, num_detectors: int) -> tuple[int, int]: + """Decode a batch using the lookup table. Returns (num_errors, num_shots).""" + errors = 0 + for i in range(batch.num_shots): + syn = batch.get_syndrome(i) + obs_true = batch.get_observable_mask(i) + + fired = tuple(d for d in range(min(num_detectors, len(syn))) if syn[d]) + predicted = table.get(fired, 0) # default: no correction + + if predicted != obs_true: + errors += 1 + + return errors, batch.num_shots + + +def main(): + parser = argparse.ArgumentParser(description="ML lookup decoder from simulation") + parser.add_argument("--distance", type=int, default=3) + parser.add_argument("--shots", type=int, default=50_000) + parser.add_argument("--basis", default="Z") + parser.add_argument("--seed", type=int, default=42) + parser.add_argument("--p2", type=float, default=0.005) + parser.add_argument("--idle-rz", type=float, default=0.0) + parser.add_argument( + "--sample-backend", default="stabilizer", + choices=["stabilizer", "statevec", "native"], + ) + args = parser.parse_args() + + import json + from pecos.qec.surface import SurfacePatch + from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model + + patch = SurfacePatch.create(distance=args.distance) + num_rounds = 2 * args.distance + tc = _build_surface_tick_circuit_for_native_model( + patch, num_rounds, args.basis, circuit_source="abstract", + ) + + num_dets = len(json.loads(tc.get_meta("detectors"))) + print(f"d={args.distance}, {num_rounds} rounds, {num_dets} detectors, {2**num_dets} possible syndromes") + + noise_params = { + "p1": args.p2 / 10, "p2": args.p2, + "p_meas": args.p2, "p_prep": args.p2, + "idle_rz": args.idle_rz, + } + + # Generate training samples + print(f"Generating {args.shots} training samples ({args.sample_backend})...") + t0 = time.perf_counter() + + if args.sample_backend in ("stabilizer", "statevec"): + from pecos_rslib_exp import depolarizing, sim_neo, stabilizer, statevec + from pecos_rslib.qec import SampleBatch + + noise = depolarizing().p1(noise_params["p1"]).p2(noise_params["p2"]) \ + .p_meas(noise_params["p_meas"]).p_prep(noise_params["p_prep"]) + if args.idle_rz > 0: + noise = noise.idle_rz(args.idle_rz) + + backend = stabilizer() if args.sample_backend == "stabilizer" else statevec() + results = sim_neo(tc).quantum(backend).noise(noise).shots(args.shots).seed(args.seed).run() + + det_json = json.loads(tc.get_meta("detectors")) + obs_json = json.loads(tc.get_meta("observables")) + num_meas = int(tc.get_meta("num_measurements")) + + # Convert to SampleBatch + detection_events = [] + observable_masks = [] + for r in results: + meas = list(r) + syn = [0] * num_dets + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + syn[i] = val + detection_events.append(syn) + obs_mask = 0 + for j, ob in enumerate(obs_json): + val = 0 + for rec in ob["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + obs_mask |= 1 << j + observable_masks.append(obs_mask) + train_batch = SampleBatch(detection_events, observable_masks) + else: + from pecos_rslib.qec import DemSampler + sampler_params = {k: v for k, v in noise_params.items() if k in ("p1", "p2", "p_meas", "p_prep")} + sampler = DemSampler.from_circuit(tc, **sampler_params) + train_batch = sampler.generate_samples(args.shots, seed=args.seed) + + t_sample = time.perf_counter() - t0 + print(f" Sampled in {t_sample:.2f}s") + + # Build lookup table + t0 = time.perf_counter() + table = build_lookup_table(train_batch, num_dets) + t_build = time.perf_counter() - t0 + print(f" Lookup table: {len(table)} unique syndromes seen (of {2**num_dets} possible)") + print(f" Built in {t_build:.4f}s") + + # Test on separate samples + test_shots = args.shots + print(f"\nGenerating {test_shots} test samples...") + if args.sample_backend in ("stabilizer", "statevec"): + results2 = sim_neo(tc).quantum(backend).noise(noise).shots(test_shots).seed(args.seed + 1000).run() + detection_events2 = [] + observable_masks2 = [] + for r in results2: + meas = list(r) + syn = [0] * num_dets + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + syn[i] = val + detection_events2.append(syn) + obs_mask = 0 + for j, ob in enumerate(obs_json): + val = 0 + for rec in ob["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + obs_mask |= 1 << j + observable_masks2.append(obs_mask) + test_batch = SampleBatch(detection_events2, observable_masks2) + else: + test_batch = sampler.generate_samples(test_shots, seed=args.seed + 1000) + + # Decode with lookup + errors_lookup, n = decode_with_lookup(test_batch, table, num_dets) + ler_lookup = errors_lookup / n + + # Compare with pymatching + from pecos.qec.surface.decode import generate_circuit_level_dem_from_builder + from pecos.qec.surface import NoiseModel + noise_obj = NoiseModel( + p1=noise_params["p1"], p2=noise_params["p2"], + p_meas=noise_params["p_meas"], p_prep=noise_params["p_prep"], + ) + dem_decomp = generate_circuit_level_dem_from_builder( + patch, num_rounds, noise_obj, basis=args.basis, + decompose_errors=True, circuit_source="abstract", + ) + dem_clean = "\n".join(l for l in dem_decomp.split("\n") if not l.startswith("logical_observable")) + stats_pm = test_batch.decode_stats(dem_clean, "pymatching") + + # Compare with coherent_dem_decomposed if available + try: + from pecos_rslib_exp import coherent_dem_decomposed + _, coherent_decomp = coherent_dem_decomposed(tc, **noise_params) + coherent_clean = "\n".join(l for l in coherent_decomp.split("\n") if not l.startswith("logical_observable")) + stats_coherent = test_batch.decode_stats(coherent_clean, "pymatching") + ler_coherent = stats_coherent.logical_error_rate + except Exception: + ler_coherent = None + + print(f"\n{'='*60}") + print(f"Results (d={args.distance}, p2={args.p2}, irz={args.idle_rz}):") + print(f"{'='*60}") + print(f" ML Lookup: LER = {ler_lookup:.6f} ({errors_lookup}/{n})") + print(f" PyMatching (from_circuit): LER = {stats_pm.logical_error_rate:.6f} ({stats_pm.num_errors}/{n})") + if ler_coherent is not None: + print(f" PyMatching (coherent): LER = {ler_coherent:.6f}") + if stats_pm.logical_error_rate > 0: + improvement = (stats_pm.logical_error_rate - ler_lookup) / stats_pm.logical_error_rate * 100 + print(f"\n ML Lookup vs PyMatching: {improvement:+.1f}%") + + +if __name__ == "__main__": + main() diff --git a/examples/surface/native_dem_threshold_sweep.py b/examples/surface/native_dem_threshold_sweep.py new file mode 100755 index 000000000..4839a9ad3 --- /dev/null +++ b/examples/surface/native_dem_threshold_sweep.py @@ -0,0 +1,4347 @@ +#!/usr/bin/env python3 +r"""Surface-code X/Z memory threshold sweep with native PECOS DEMs. + +This example runs rotated surface-code memory experiments using: + +- Guppy surface-memory programs from ``pecos.guppy.surface.make_surface_code`` +- ``sim(...).classical(selene_engine())`` for end-to-end execution +- direct ``selene_sim`` execution with either Selene ``Stim`` or the PECOS + Selene stabilizer plugin +- optional native DEM sampling via ``build_native_sampler(...)`` +- a depolarizing noise model with ``p2 = p``, ``p1 = p/30``, ``p_meas = p_prep = p/3`` +- ``SurfaceDecoder(...)`` with PECOS-native DEMs (PyMatching or Tesseract) + +For the ``sim`` backend, decoding is performed relative to a cached noiseless +reference trajectory from the same Guppy/QIS circuit. This makes the gate-level +path compatible with the native DEM's "deviations from ideal trajectory" view. + +Instead of relying on one fixed memory duration, the default workflow samples +about four evenly spaced integer round counts across the window +``r in [2d, 3d]`` for each ``(distance, basis, p)`` point and fits a +per-round logical error rate ``epsilon`` via + + p_L(r) ~= 0.5 * (1 - (1 - 2 * epsilon) ** r) + +This is a cleaner way to reduce temporal-boundary sensitivity than trying to +decode only the "middle" rounds of a finite spacetime volume. + +Example: + python examples/surface/native_dem_threshold_sweep.py --shots 200 + + python examples/surface/native_dem_threshold_sweep.py \\ + --distances 3 5 7 9 \\ + --duration-multipliers 2 2.25 2.5 2.75 3 \\ + --error-rates 0.001 0.002 0.003 0.004 0.005 0.006 \\ + --bases X Z \\ + --shots 500 \\ + --save-json --save-svg + + python examples/surface/native_dem_threshold_sweep.py \\ + --sample-backend compare \\ + --distances 3 5 \\ + --error-rates 0.001 0.002 + + python examples/surface/native_dem_threshold_sweep.py \\ + --sample-backend compare_all \\ + --distances 3 5 \\ + --error-rates 0.003 +""" + +from __future__ import annotations + +import argparse +import atexit +import contextlib +import hashlib +import html +import itertools +import json +import math +import statistics +import tempfile +import time +from dataclasses import asdict, dataclass +from functools import cache +from pathlib import Path +from typing import TYPE_CHECKING, Any + +if TYPE_CHECKING: + from types import ModuleType + + import numpy as np + from matplotlib.axes import Axes + from matplotlib.figure import Figure + from matplotlib.patches import Rectangle + + +@dataclass(frozen=True) +class SweepPoint: + """Decoded statistics for one memory experiment duration.""" + + backend: str + distance: int + basis: str + physical_error_rate: float + total_rounds: int + num_shots: int + num_logical_errors: int + num_raw_errors: int | None + logical_error_rate: float + raw_error_rate: float | None + + +@dataclass(frozen=True) +class FitSummary: + """Fitted per-round logical error summary for one ``(d, basis, p)`` point.""" + + backend: str + distance: int + basis: str + physical_error_rate: float + num_shots_per_round_point: int + round_values: tuple[int, ...] + observed_logical_error_rates: tuple[float, ...] + observed_raw_error_rates: tuple[float | None, ...] + fitted_logical_error_rate_per_round: float + fitted_projected_logical_error_rate_over_d_rounds: float + fit_root_mean_square_error: float + observed_logical_error_counts: tuple[int, ...] = () + observed_logical_error_rate_lower_bounds: tuple[float, ...] = () + observed_logical_error_rate_upper_bounds: tuple[float, ...] = () + fitted_logical_error_rate_per_round_ci_low: float | None = None + fitted_logical_error_rate_per_round_ci_high: float | None = None + fitted_projected_logical_error_rate_over_d_rounds_ci_low: float | None = None + fitted_projected_logical_error_rate_over_d_rounds_ci_high: float | None = None + + +@dataclass(frozen=True) +class DistanceScalingFitSummary: + """Fit ``epsilon(d) ~= A * (p / p_th) ** ((d + 1) / 2)`` at fixed ``p``.""" + + backend: str + basis: str + physical_error_rate: float + distances: tuple[int, ...] + fitted_prefactor: float + fitted_threshold: float + fitted_suppression_factor: float + fit_root_mean_square_log_error: float + + +@dataclass(frozen=True) +class GlobalScalingFitSummary: + """Fit the standard below-threshold surface-code scaling ansatz.""" + + backend: str + basis: str + distances: tuple[int, ...] + physical_error_rates: tuple[float, ...] + fitted_prefactor: float + fitted_threshold: float + fit_root_mean_square_log_error: float + + +@dataclass(frozen=True) +class PerDistancePowerLawFitSummary: + """Fit ``epsilon(p) ~= C_d * p ** beta_d`` for one distance.""" + + backend: str + basis: str + distance: int + physical_error_rates: tuple[float, ...] + fitted_prefactor: float + fitted_exponent: float + expected_distance_scaling_exponent: float + fit_root_mean_square_log_error: float + fitted_exponent_std_error: float = 0.0 + + +@dataclass(frozen=True) +class FSSThresholdFitSummary: + """Polynomial finite-size-scaling threshold fit using the Wang-Harrington-Preskill form. + + Reference: Wang, Harrington, Preskill, *Confinement-Higgs transition in a disordered + gauge theory and the accuracy threshold for quantum memory* (arXiv:quant-ph/0207088). + Fit model: ``p_L = a + b*x + c*x**2`` with ``x = (p - p_th) * d**(1 / nu)``. Data + should bracket the threshold; the Watson-Barrett constraint ``p > 1/(4d)`` + (arXiv:1312.5213) also applies to the domain of validity. + + Delegates to ``pecos.analysis.threshold_curve.threshold_fit`` + ``func`` so + every surface-code performance report uses the same canonical fit routine + as the rest of PECOS. + """ + + backend: str + basis: str + p_th: float + p_th_std_error: float + nu: float + nu_std_error: float + coeff_a: float + coeff_a_std_error: float + coeff_b: float + coeff_b_std_error: float + coeff_c: float + coeff_c_std_error: float + num_points: int + fit_window_low: float + fit_window_high: float + reference: str = "Wang-Harrington-Preskill (arXiv:quant-ph/0207088)" + + +@dataclass(frozen=True) +class PairwiseLambdaSummary: + """Empirical ``Lambda_{d/(d+2)}`` ratios at one fixed physical error rate.""" + + backend: str + basis: str + physical_error_rate: float + distance_low: int + distance_high: int + lambda_d_over_d_plus_2: float + + +@dataclass(frozen=True) +class DashboardPlot: + """One SVG plot entry for the optional HTML dashboard.""" + + section: str + title: str + filename: str + backend: str + basis: str | None = None + physical_error_rate: float | None = None + + +@dataclass(frozen=True) +class _DecoderRuntime: + """Reusable decoder-side runtime for one native comparison point shape.""" + + patch: Any + logical_qubits: tuple[int, ...] + num_x_stab: int + num_z_stab: int + noise: Any + decoder: Any + + +@dataclass(frozen=True) +class _NativeSamplerRuntime: + """Reusable sampler + decoder bundle for one traced/native DEM shape.""" + + decoder_runtime: _DecoderRuntime + sampler: Any + dem_decoder: Any + dem_str: str | None = None + + +_CACHED_SELENE_INSTANCES: list[Any] = [] +_FIT_CONFIDENCE_LEVEL = 0.95 +_FIT_BOOTSTRAP_SAMPLES = 200 + + +def _cleanup_cached_selene_instances() -> None: + """Best-effort cleanup for temporary Selene build directories.""" + while _CACHED_SELENE_INSTANCES: + instance = _CACHED_SELENE_INSTANCES.pop() + with contextlib.suppress(Exception): + instance.delete_files() + + +atexit.register(_cleanup_cached_selene_instances) + + +def _backend_runtime_label(sample_backend: str, native_circuit_source: str = "abstract") -> str: + """Describe one sampling backend in human-readable terms.""" + # Handle "backend:decoder" labels from multi-decoder comparison + if ":" in sample_backend: + base, decoder = sample_backend.split(":", 1) + base_label = _backend_runtime_label(base, native_circuit_source) + return f"{base_label} [decoder={decoder}]" + if sample_backend == "sim": + return ( + "sim(Guppy(...)).classical(selene_engine()).quantum(pecos.stabilizer()) " + f"+ PECOS depolarizing noise + native DEM source={native_circuit_source} + noiseless " + "reference-trajectory calibration" + ) + if sample_backend == "selene_sim": + return ( + "direct selene_sim (compile_guppy_to_hugr + build/run_shots) with Selene Stim " + f"+ Selene DepolarizingErrorModel + native DEM source={native_circuit_source} " + "+ noiseless reference-trajectory calibration" + ) + if sample_backend == "selene_stabilizer_plugin": + return ( + "direct selene_sim (compile_guppy_to_hugr + build/run_shots) with the PECOS " + "Selene StabilizerPlugin + Selene DepolarizingErrorModel + native DEM source=" + f"{native_circuit_source} + noiseless reference-trajectory calibration" + ) + if sample_backend == "native_sampler": + return f"build_native_sampler(..., circuit_source={native_circuit_source!r}) + DEM decoder on the native DEM" + msg = f"Unknown sample backend: {sample_backend}" + raise ValueError(msg) + + +def _predicted_observable_flip(result: object) -> int: + """Extract the predicted logical observable flip from a DEM decoder result.""" + observables_mask = getattr(result, "observables_mask", None) + if observables_mask is not None: + return int(observables_mask & 1) + correction = getattr(result, "correction", []) + return int(correction[0]) if len(correction) > 0 else 0 + + +def _format_rate(value: float | None) -> str: + """Format a logical or raw error rate for compact terminal output.""" + if value is None: + return "n/a" + return f"{value:.6e}" + + +def ler_per_round_exp(logical_error_rate: float, num_rounds: int) -> float: + """Extract a per-round logical error rate from one duration point.""" + if num_rounds <= 0: + msg = "num_rounds must be positive" + raise ValueError(msg) + if logical_error_rate <= 0.0: + return 0.0 + if logical_error_rate >= 0.5: + return 0.5 + return 0.5 * (1.0 - (1.0 - 2.0 * logical_error_rate) ** (1.0 / num_rounds)) + + +def ler_over_rounds(per_round_rate: float, num_rounds: float) -> float: + """Project a per-round logical error rate over ``num_rounds`` rounds.""" + if num_rounds <= 0: + msg = "num_rounds must be positive" + raise ValueError(msg) + if per_round_rate <= 0.0: + return 0.0 + if per_round_rate >= 0.5: + return 0.5 + return 0.5 * (1.0 - (1.0 - 2.0 * per_round_rate) ** num_rounds) + + +def _wilson_interval( + num_successes: int, + num_trials: int, + *, + confidence_level: float = _FIT_CONFIDENCE_LEVEL, +) -> tuple[float, float]: + """Return a Wilson score interval for one binomial proportion.""" + if num_trials <= 0: + msg = "num_trials must be positive" + raise ValueError(msg) + z = statistics.NormalDist().inv_cdf(0.5 + confidence_level / 2.0) + p_hat = num_successes / num_trials + z_sq_over_n = (z * z) / num_trials + denom = 1.0 + z_sq_over_n + center = (p_hat + 0.5 * z_sq_over_n) / denom + half_width = z * math.sqrt((p_hat * (1.0 - p_hat) + (z * z) / (4.0 * num_trials)) / num_trials) / denom + return max(0.0, center - half_width), min(1.0, center + half_width) + + +def _fit_summary_metric_interval(summary: FitSummary, metric: str) -> tuple[float, float, float]: + """Return ``(value, low, high)`` for one plotted fit metric.""" + value = getattr(summary, metric) + if metric == "fitted_logical_error_rate_per_round": + low = summary.fitted_logical_error_rate_per_round_ci_low + high = summary.fitted_logical_error_rate_per_round_ci_high + elif metric == "fitted_projected_logical_error_rate_over_d_rounds": + low = summary.fitted_projected_logical_error_rate_over_d_rounds_ci_low + high = summary.fitted_projected_logical_error_rate_over_d_rounds_ci_high + else: + low = None + high = None + return ( + value, + value if low is None else low, + value if high is None else high, + ) + + +def _format_interval(low: float | None, high: float | None, value: float) -> str: + """Format one fit interval for terminal output.""" + resolved_low = value if low is None else low + resolved_high = value if high is None else high + return f"[{resolved_low:.6e}, {resolved_high:.6e}]" + + +def _stable_bootstrap_seed(points: list[SweepPoint]) -> int: + """Derive a stable RNG seed for one fit-summary point group.""" + first = points[0] + key = "|".join( + [ + first.backend, + first.basis, + str(first.distance), + f"{first.physical_error_rate:.12g}", + *(f"{point.total_rounds}:{point.num_shots}:{point.num_logical_errors}" for point in points), + ], + ) + digest = hashlib.blake2b(key.encode("utf-8"), digest_size=8).digest() + return int.from_bytes(digest, byteorder="big", signed=False) + + +def _percentile_interval( + values: list[float], + *, + confidence_level: float = _FIT_CONFIDENCE_LEVEL, +) -> tuple[float, float]: + """Return an empirical central percentile interval for a sample.""" + if not values: + msg = "Need at least one sample value" + raise ValueError(msg) + ordered = sorted(values) + if len(ordered) == 1: + return ordered[0], ordered[0] + + lower_q = 0.5 * (1.0 - confidence_level) + upper_q = 1.0 - lower_q + + def interpolate(probability: float) -> float: + position = probability * (len(ordered) - 1) + lower_index = math.floor(position) + upper_index = math.ceil(position) + if lower_index == upper_index: + return ordered[lower_index] + fraction = position - lower_index + return ordered[lower_index] * (1.0 - fraction) + ordered[upper_index] * fraction + + return interpolate(lower_q), interpolate(upper_q) + + +def _fit_summary_confidence_intervals(points: list[SweepPoint]) -> tuple[float, float, float, float]: + """Bootstrap fit uncertainty for one ``(d, basis, p)`` point group.""" + ordered = sorted(points, key=lambda point: point.total_rounds) + fitted_per_round = _fit_per_round_rate(ordered) + fitted_projected = ler_over_rounds(fitted_per_round, ordered[0].distance) + + try: + import numpy as np + except ImportError: # pragma: no cover + return fitted_per_round, fitted_per_round, fitted_projected, fitted_projected + + shot_counts = np.asarray([point.num_shots for point in ordered], dtype=np.int64) + observed_rates = np.asarray( + [min(max(point.logical_error_rate, 0.0), 1.0) for point in ordered], + dtype=np.float64, + ) + rng = np.random.default_rng(_stable_bootstrap_seed(ordered)) + bootstrap_counts = rng.binomial(n=shot_counts, p=observed_rates, size=(_FIT_BOOTSTRAP_SAMPLES, len(ordered))) + + bootstrap_per_round: list[float] = [] + bootstrap_projected: list[float] = [] + for sample_counts in bootstrap_counts: + sample_points: list[SweepPoint] = [] + for point, sample_count in zip(ordered, sample_counts, strict=True): + count = int(sample_count) + sample_points.append( + SweepPoint( + backend=point.backend, + distance=point.distance, + basis=point.basis, + physical_error_rate=point.physical_error_rate, + total_rounds=point.total_rounds, + num_shots=point.num_shots, + num_logical_errors=count, + num_raw_errors=point.num_raw_errors, + logical_error_rate=(count / point.num_shots) if point.num_shots else 0.0, + raw_error_rate=point.raw_error_rate, + ), + ) + sample_fit = _fit_per_round_rate(sample_points) + bootstrap_per_round.append(sample_fit) + bootstrap_projected.append(ler_over_rounds(sample_fit, ordered[0].distance)) + + per_round_low, per_round_high = _percentile_interval(bootstrap_per_round) + projected_low, projected_high = _percentile_interval(bootstrap_projected) + return per_round_low, per_round_high, projected_low, projected_high + + +def _rounds_from_multiplier(distance: int, duration_multiplier: float) -> int: + """Convert a duration multiplier into an integer round count.""" + total_rounds = round(duration_multiplier * distance) + if total_rounds <= 0: + msg = f"duration multiplier {duration_multiplier!r} produced non-positive rounds for d={distance}" + raise ValueError(msg) + return total_rounds + + +def _evenly_spaced_values(start: float, stop: float, num_points: int) -> list[float]: + """Return ``num_points`` evenly spaced values from ``start`` to ``stop`` inclusive.""" + if num_points <= 0: + msg = "num_points must be positive" + raise ValueError(msg) + if num_points == 1: + return [0.5 * (start + stop)] + step = (stop - start) / (num_points - 1) + return [start + index * step for index in range(num_points)] + + +def _duration_rounds_for_distance( + distance: int, + *, + explicit_multipliers: list[float] | None, + duration_min_multiplier: float, + duration_max_multiplier: float, + duration_num_points: int, +) -> tuple[int, ...]: + """Return the effective integer round counts to sample for one distance.""" + if explicit_multipliers is not None: + return tuple(sorted({_rounds_from_multiplier(distance, multiplier) for multiplier in explicit_multipliers})) + + start_round = _rounds_from_multiplier(distance, duration_min_multiplier) + stop_round = _rounds_from_multiplier(distance, duration_max_multiplier) + if stop_round < start_round: + msg = "duration_max_multiplier must be at least duration_min_multiplier" + raise ValueError(msg) + raw_rounds = _evenly_spaced_values(float(start_round), float(stop_round), duration_num_points) + return tuple(sorted({max(1, round(value)) for value in raw_rounds})) + + +def _reshape_round_values(flat_values: list[int], num_rounds: int, width: int, label: str) -> list[Any]: + """Reshape a flattened per-shot result register into round slices.""" + import numpy as np + + if width <= 0: + return [] + expected = num_rounds * width + values = np.asarray(flat_values, dtype=np.uint8) + if values.size != expected: + msg = ( + f"Register {label!r} has {values.size} bits for one shot, " + f"expected {expected} = {num_rounds} rounds * {width} bits" + ) + raise ValueError(msg) + return [values[i * width : (i + 1) * width] for i in range(num_rounds)] + + +def _logical_qubits_for_basis(patch: object, basis: str) -> tuple[int, ...]: + """Get the logical support used for the final parity check.""" + geom = patch.geometry + if basis.upper() == "Z": + return tuple(geom.logical_z.data_qubits if geom.logical_z else ()) + return tuple(geom.logical_x.data_qubits if geom.logical_x else ()) + + +def _result_rows_for_key(result_dict: dict[str, Any], key: str) -> list[Any]: + """Fetch per-shot rows for a named result register.""" + if key in result_dict: + rows = result_dict[key] + if isinstance(rows, list): + return rows + available = ", ".join(sorted(result_dict)) + msg = f"Expected result register {key!r}, available registers: {available}" + raise KeyError(msg) + + +@cache +def _surface_patch(distance: int) -> object: + """Cache surface patch geometry shared across many sweep points.""" + from pecos.qec.surface import SurfacePatch + + return SurfacePatch.create(distance=distance) + + +_CHECK_MATRIX_DECODERS = {"bp_osd", "bp_lsd", "union_find", "relay_bp", "min_sum_bp"} + + +def _noise_model_description(args: argparse.Namespace) -> str: + """Human-readable noise model string for reports.""" + p1s = getattr(args, "p1_scale", 1.0 / 30.0) + pms = getattr(args, "p_meas_scale", 1.0 / 3.0) + pps = getattr(args, "p_prep_scale", 1.0 / 3.0) + return f"depolarizing with p1={p1s:.4g}*p, p2=p, p_meas={pms:.4g}*p, p_prep={pps:.4g}*p" + + +def _create_dem_decoder(decoder_type: str, dem_str: str, *, tesseract_beam: int = 5) -> object: + """Create a DEM-level decoder from a DEM string. + + Supports MWPM decoders (pymatching), search decoders (tesseract), and + check-matrix decoders (bp_osd, bp_lsd, union_find, relay_bp, min_sum_bp) + via DemAwareDecoder which extracts the check matrix from the DEM. + """ + if decoder_type == "tesseract": + from pecos_rslib.decoders import TesseractDecoder + + dem_filtered = "\n".join(line for line in dem_str.split("\n") if not line.startswith("logical_observable")) + return TesseractDecoder.from_dem(dem_filtered, preset="fast", det_beam=tesseract_beam) + + if decoder_type in _CHECK_MATRIX_DECODERS: + from pecos_rslib.decoders import DemAwareDecoder + + dem_filtered = "\n".join(line for line in dem_str.split("\n") if not line.startswith("logical_observable")) + return DemAwareDecoder.from_dem(dem_filtered, decoder_type=decoder_type) + + from pecos_rslib.decoders import PyMatchingDecoder + + return PyMatchingDecoder.from_dem(dem_str) + + +def _decode_one_shot(dem_decoder: object, events_flat: list[int]) -> object: + """Decode one shot using whichever DEM decoder was created. + + Tesseract.decode() wants sparse indices; decode_syndrome() accepts dense vectors. + PyMatching.decode() accepts dense vectors directly. + """ + if hasattr(dem_decoder, "decode_syndrome"): + return dem_decoder.decode_syndrome(events_flat) + return dem_decoder.decode(events_flat) + + +def _decode_all_shots( + dem_decoder: object, + detection_events: np.ndarray, + observable_flips: np.ndarray, + num_shots: int, +) -> int: + """Decode all shots using the fastest available path. + + For PyMatching: uses decode_batch with flattened numpy array (no Python loop). + For Tesseract: uses decode_batch with parallel rayon workers. + For others: falls back to per-shot Python loop. + + Returns the number of logical errors. + """ + import numpy as np + + true_flips = ( + observable_flips[:, 0].astype(np.uint8) + if observable_flips.shape[1] > 0 + else np.zeros(num_shots, dtype=np.uint8) + ) + + # PyMatching batch: takes flattened (num_shots * num_detectors) u8 array + from pecos_rslib.decoders import PyMatchingDecoder + + if isinstance(dem_decoder, PyMatchingDecoder): + flat = detection_events.astype(np.uint8).flatten().tolist() + predictions = dem_decoder.decode_batch(flat, num_shots) + # Each prediction is a list of observables; check index 0 + predicted = np.array([p[0] if p else 0 for p in predictions], dtype=np.uint8) + return int(np.sum(predicted != true_flips)) + + # Tesseract batch: takes list of syndromes, parallel rayon + from pecos_rslib.decoders import TesseractDecoder + + if isinstance(dem_decoder, TesseractDecoder): + syndromes = [detection_events[i].astype(np.uint8).tolist() for i in range(num_shots)] + batch_results = dem_decoder.decode_batch(syndromes) + num_errors = 0 + for shot_idx, result in enumerate(batch_results): + predicted_flip = int(result.observables_mask & 1) + num_errors += int(predicted_flip != true_flips[shot_idx]) + return num_errors + + # Fallback: per-shot loop (DemAwareDecoder, etc.) + num_errors = 0 + for shot_idx in range(num_shots): + events_flat = detection_events[shot_idx].astype(np.uint8).tolist() + decode_result = _decode_one_shot(dem_decoder, events_flat) + predicted_flip = _predicted_observable_flip(decode_result) + num_errors += int(predicted_flip != true_flips[shot_idx]) + return num_errors + + +@cache +def _decoder_runtime( + distance: int, + total_rounds: int, + basis: str, + physical_error_rate: float, + dem_mode: str, + native_circuit_source: str, + decoder_type: str = "pymatching", + ancilla_budget: int | None = None, + p1_scale: float = 0.1, + p_meas_scale: float = 0.5, + p_prep_scale: float = 0.5, +) -> _DecoderRuntime: + """Build and cache the expensive native decoder-side objects once.""" + from pecos.qec.surface import NoiseModel, SurfaceDecoder + + basis = basis.upper() + patch = _surface_patch(distance) + noise = NoiseModel( + p1=physical_error_rate * p1_scale, + p2=physical_error_rate, + p_meas=physical_error_rate * p_meas_scale, + p_prep=physical_error_rate * p_prep_scale, + ) + decoder = SurfaceDecoder( + patch, + num_rounds=total_rounds, + noise=noise, + decoder_type=decoder_type, + use_circuit_level_dem=True, + circuit_level_dem_mode=dem_mode, + circuit_level_dem_source=native_circuit_source, + ancilla_budget=ancilla_budget, + ) + return _DecoderRuntime( + patch=patch, + logical_qubits=_logical_qubits_for_basis(patch, basis), + num_x_stab=len(patch.geometry.x_stabilizers), + num_z_stab=len(patch.geometry.z_stabilizers), + noise=noise, + decoder=decoder, + ) + + +@cache +def _native_sampler_runtime( + distance: int, + total_rounds: int, + basis: str, + physical_error_rate: float, + dem_mode: str, + native_circuit_source: str, + decoder_type: str = "pymatching", + ancilla_budget: int | None = None, + p1_scale: float = 0.1, + p_meas_scale: float = 0.5, + p_prep_scale: float = 0.5, +) -> _NativeSamplerRuntime: + """Build and cache the native sampler + decoder bundle once.""" + from pecos.qec.surface import build_native_sampler + from pecos.qec.surface.decode import generate_circuit_level_dem_from_builder + + runtime = _decoder_runtime( + distance, + total_rounds, + basis, + physical_error_rate, + dem_mode, + native_circuit_source, + decoder_type=decoder_type, + ancilla_budget=ancilla_budget, + p1_scale=p1_scale, + p_meas_scale=p_meas_scale, + p_prep_scale=p_prep_scale, + ) + sampler = build_native_sampler( + runtime.patch, + total_rounds, + runtime.noise, + basis=basis, + circuit_source=native_circuit_source, + ancilla_budget=ancilla_budget, + ) + # PyMatching needs decomposed (graph-like) DEMs; Tesseract and check-matrix + # decoders handle hyperedges natively and should get the full DEM. + if decoder_type == "pymatching": + dem_str = runtime.decoder.get_dem(basis.upper(), circuit_level=True) + else: + dem_str = generate_circuit_level_dem_from_builder( + runtime.patch, + total_rounds, + runtime.noise, + basis=basis, + decompose_errors=False, + circuit_source=native_circuit_source, + ancilla_budget=ancilla_budget, + ) + dem_decoder = _create_dem_decoder(decoder_type, dem_str) + # The traced-QIS sampler stack has a noticeable one-time initialization cost + # on its first sample. Pay that once when the cached runtime is created so + # subsequent point evaluations stay on the true steady-state path. + warm_det_events, _ = sampler.sample(num_shots=1, seed=0) + _decode_one_shot(dem_decoder, warm_det_events[0].astype(int).tolist()) + # Filter logical_observable lines for decoders that need it + dem_str_filtered = "\n".join(line for line in dem_str.split("\n") if not line.startswith("logical_observable")) + return _NativeSamplerRuntime( + decoder_runtime=runtime, + sampler=sampler, + dem_decoder=dem_decoder, + dem_str=dem_str_filtered, + ) + + +@cache +def _sim_reference_trajectory( + sample_backend: str, + distance: int, + total_rounds: int, + basis: str, +) -> tuple[tuple[tuple[int, ...], ...], tuple[tuple[int, ...], ...], tuple[int, ...]]: + """Cache a noiseless gate-level trajectory used as a decoding reference.""" + import numpy as np + from pecos.qec.surface import SurfacePatch + + patch = SurfacePatch.create(distance=distance) + result_dict = _run_gate_backend_result_dict( + sample_backend=sample_backend, + distance=distance, + basis=basis, + physical_error_rate=0.0, + total_rounds=total_rounds, + num_shots=1, + seed=0, + ) + + synx_rows = _reshape_round_values( + _result_rows_for_key(result_dict, "synx")[0], + total_rounds, + len(patch.geometry.x_stabilizers), + "synx", + ) + synz_rows = _reshape_round_values( + _result_rows_for_key(result_dict, "synz")[0], + total_rounds, + len(patch.geometry.z_stabilizers), + "synz", + ) + final = np.asarray(_result_rows_for_key(result_dict, "final")[0], dtype=np.uint8) + + return ( + tuple(tuple(int(v) for v in row) for row in synx_rows), + tuple(tuple(int(v) for v in row) for row in synz_rows), + tuple(int(v) for v in final.tolist()), + ) + + +@cache +def _compiled_guppy_hugr(distance: int, total_rounds: int, basis: str) -> bytes: + """Cache compiled HUGR bytes for the direct selene_sim backend.""" + from pecos.compilation_pipeline import compile_guppy_to_hugr + from pecos.guppy import make_surface_code + + program = make_surface_code(distance=distance, num_rounds=total_rounds, basis=basis) + return compile_guppy_to_hugr(program) + + +@cache +def _selene_instance(distance: int, total_rounds: int, basis: str) -> object: + """Cache a built Selene instance for one circuit shape.""" + from selene_sim import build + + instance = build( + _compiled_guppy_hugr(distance, total_rounds, basis), + name=f"surface_d{distance}_{basis.lower()}_r{total_rounds}", + ) + _CACHED_SELENE_INSTANCES.append(instance) + return instance + + +def _run_gate_backend_result_dict( + *, + sample_backend: str, + distance: int, + basis: str, + physical_error_rate: float, + total_rounds: int, + num_shots: int, + seed: int, + timing_sink: dict[str, float] | None = None, + p1_scale: float = 0.1, + p_meas_scale: float = 0.5, + p_prep_scale: float = 0.5, +) -> dict[str, list[list[int]]]: + """Run one gate-level backend and normalize results to a shot-map-like dict.""" + import os + import tempfile + from collections import defaultdict + + import pecos + from pecos.guppy import get_num_qubits, make_surface_code + + def run_direct_selene_backend(*, simulator: object) -> dict[str, list[list[int]]]: + from selene_sim import DepolarizingErrorModel, SimpleRuntime + + backend_start = time.perf_counter() + os.environ.setdefault( + "ZIG_GLOBAL_CACHE_DIR", + str(Path(tempfile.gettempdir()) / "pecos_zig_global_cache"), + ) + os.environ.setdefault( + "ZIG_LOCAL_CACHE_DIR", + str(Path(tempfile.gettempdir()) / "pecos_zig_local_cache"), + ) + + compile_start = time.perf_counter() + _compiled_guppy_hugr(distance, total_rounds, basis) + compile_seconds = time.perf_counter() - compile_start + + build_start = time.perf_counter() + instance = _selene_instance(distance, total_rounds, basis) + build_seconds = time.perf_counter() - build_start + + reset_start = time.perf_counter() + instance.delete_run_directories() + instance.runs.mkdir(parents=True, exist_ok=True) + reset_seconds = time.perf_counter() - reset_start + + error_model_start = time.perf_counter() + error_model = DepolarizingErrorModel( + p_1q=physical_error_rate * p1_scale, + p_2q=physical_error_rate, + p_meas=physical_error_rate * p_meas_scale, + p_prep=physical_error_rate * p_prep_scale, + ) + error_model_seconds = time.perf_counter() - error_model_start + + result_dict: dict[str, list[list[int]]] = defaultdict(list) + run_start = time.perf_counter() + for shot_results in instance.run_shots( + simulator=simulator, + n_qubits=get_num_qubits(distance), + n_shots=num_shots, + error_model=error_model, + runtime=SimpleRuntime(), + random_seed=seed, + n_processes=1, + ): + shot_rows: dict[str, list[int]] = defaultdict(list) + for name, values in shot_results: + shot_rows[name].extend(int(v) for v in values) + for name, values in shot_rows.items(): + result_dict[name].append(values) + run_seconds = time.perf_counter() - run_start + if timing_sink is not None: + timing_sink.update( + { + "compile_hugr_seconds": compile_seconds, + "instance_build_seconds": build_seconds, + "instance_reset_seconds": reset_seconds, + "error_model_seconds": error_model_seconds, + "run_and_parse_seconds": run_seconds, + "total_seconds": time.perf_counter() - backend_start, + }, + ) + return dict(result_dict) + + if sample_backend == "sim": + backend_start = time.perf_counter() + noise_start = time.perf_counter() + noise_model = pecos.depolarizing_noise() + noise_model.set_probabilities( + physical_error_rate * p_prep_scale, # p_prep + physical_error_rate * p_meas_scale, # p_meas_0 + physical_error_rate * p_meas_scale, # p_meas_1 + physical_error_rate * p1_scale, # p1 (single-qubit gates) + physical_error_rate, # p2 (two-qubit gates) + ) + noise_seconds = time.perf_counter() - noise_start + program_start = time.perf_counter() + program = make_surface_code(distance=distance, num_rounds=total_rounds, basis=basis) + program_seconds = time.perf_counter() - program_start + run_start = time.perf_counter() + shot_vec = ( + pecos.sim(program) + .classical(pecos.selene_engine()) + .quantum(pecos.stabilizer()) + .qubits(get_num_qubits(distance)) + .noise(noise_model) + .seed(seed) + .run(num_shots) + ) + run_seconds = time.perf_counter() - run_start + shot_map_start = time.perf_counter() + shot_map = shot_vec.to_shot_map() + shot_map_seconds = time.perf_counter() - shot_map_start + dict_start = time.perf_counter() + result_dict = shot_map.to_dict() + dict_seconds = time.perf_counter() - dict_start + if timing_sink is not None: + timing_sink.update( + { + "noise_model_seconds": noise_seconds, + "program_build_seconds": program_seconds, + "run_seconds": run_seconds, + "to_shot_map_seconds": shot_map_seconds, + "to_dict_seconds": dict_seconds, + "total_seconds": time.perf_counter() - backend_start, + }, + ) + return result_dict + + if sample_backend == "selene_sim": + from selene_sim import Stim + + return run_direct_selene_backend(simulator=Stim()) + + if sample_backend == "selene_stabilizer_plugin": + from pecos_selene_stabilizer import StabilizerPlugin + + return run_direct_selene_backend(simulator=StabilizerPlugin()) + + msg = f"Unknown gate backend: {sample_backend}" + raise ValueError(msg) + + +def _profile_gate_backends( + *, + backends: list[str], + distances: list[int], + bases: list[str], + error_rates: list[float], + duration_rounds_by_distance: dict[int, tuple[int, ...]], + shots: int, + seed: int, + warmup_repetitions: int, + benchmark_repetitions: int, +) -> None: + """Profile gate backends and print a phase breakdown.""" + if warmup_repetitions < 0: + msg = "warmup_repetitions must be non-negative" + raise ValueError(msg) + if benchmark_repetitions <= 0: + msg = "benchmark_repetitions must be positive" + raise ValueError(msg) + + print() + print("Gate Backend Profile") + print(f" warmup repetitions : {warmup_repetitions}") + print(f" timed repetitions : {benchmark_repetitions}") + + profile_keys: dict[str, list[str]] = { + "selene_sim": [ + "compile_hugr_seconds", + "instance_build_seconds", + "instance_reset_seconds", + "error_model_seconds", + "run_and_parse_seconds", + ], + "selene_stabilizer_plugin": [ + "compile_hugr_seconds", + "instance_build_seconds", + "instance_reset_seconds", + "error_model_seconds", + "run_and_parse_seconds", + ], + "sim": [ + "noise_model_seconds", + "program_build_seconds", + "run_seconds", + "to_shot_map_seconds", + "to_dict_seconds", + ], + } + + combinations = [ + (distance, basis, physical_error_rate, total_rounds) + for basis in bases + for distance in distances + for physical_error_rate in error_rates + for total_rounds in duration_rounds_by_distance[distance] + ] + + for combo_idx, (distance, basis, physical_error_rate, total_rounds) in enumerate(combinations, start=1): + print() + print( + f"[profile {combo_idx}/{len(combinations)}] " + f"basis={basis} d={distance} p={physical_error_rate:.5g} r={total_rounds} shots={shots}", + ) + backend_totals: dict[str, float] = {} + for backend_index, backend in enumerate(backends, start=1): + combo_seed = seed + combo_idx * 1000 + backend_index * 100 + for rep in range(warmup_repetitions): + _run_gate_backend_result_dict( + sample_backend=backend, + distance=distance, + basis=basis, + physical_error_rate=physical_error_rate, + total_rounds=total_rounds, + num_shots=shots, + seed=combo_seed + rep, + ) + + runs: list[dict[str, float]] = [] + for rep in range(benchmark_repetitions): + timing: dict[str, float] = {} + _run_gate_backend_result_dict( + sample_backend=backend, + distance=distance, + basis=basis, + physical_error_rate=physical_error_rate, + total_rounds=total_rounds, + num_shots=shots, + seed=combo_seed + warmup_repetitions + rep, + timing_sink=timing, + ) + runs.append(timing) + + total_values = [run["total_seconds"] for run in runs] + mean_total = statistics.fmean(total_values) + median_total = statistics.median(total_values) + shots_per_second = shots / mean_total if mean_total > 0 else float("inf") + backend_totals[backend] = mean_total + print( + f" [{backend}] mean={mean_total:.3f}s " + f"median={median_total:.3f}s throughput={shots_per_second:.3f} shots/s", + ) + for key in profile_keys[backend]: + phase_values = [run[key] for run in runs] + mean_phase = statistics.fmean(phase_values) + phase_fraction = mean_phase / mean_total if mean_total > 0 else 0.0 + print(f" {key}: {mean_phase:.3f}s ({phase_fraction:.1%})") + + if "selene_sim" in backend_totals: + reference = backend_totals["selene_sim"] + print(" relative_to_selene_sim:") + for backend in backends: + ratio = backend_totals[backend] / reference if reference > 0 else float("inf") + print(f" {backend}: {ratio:.3f}") + + +def _run_memory_point( + *, + sample_backend: str, + distance: int, + basis: str, + physical_error_rate: float, + total_rounds: int, + num_shots: int, + dem_mode: str, + native_circuit_source: str, + seed: int, + decoder_type: str = "pymatching", + backend_label: str | None = None, + ancilla_budget: int | None = None, + p1_scale: float = 0.1, + p_meas_scale: float = 0.5, + p_prep_scale: float = 0.5, +) -> SweepPoint: + """Run one surface-memory point and decode it with native PECOS DEMs.""" + import numpy as np + + basis = basis.upper() + decoder_runtime = _decoder_runtime( + distance, + total_rounds, + basis, + physical_error_rate, + dem_mode, + native_circuit_source, + decoder_type=decoder_type, + ancilla_budget=ancilla_budget, + p1_scale=p1_scale, + p_meas_scale=p_meas_scale, + p_prep_scale=p_prep_scale, + ) + patch = decoder_runtime.patch + num_x_stab = decoder_runtime.num_x_stab + num_z_stab = decoder_runtime.num_z_stab + logical_qubits = decoder_runtime.logical_qubits + decoder = decoder_runtime.decoder + + num_logical_errors = 0 + num_raw_errors: int | None = 0 + + if sample_backend in {"sim", "selene_sim", "selene_stabilizer_plugin"}: + ref_synx_rows, ref_synz_rows, ref_final_row = _sim_reference_trajectory( + sample_backend, + distance, + total_rounds, + basis.upper(), + ) + ref_synx_list = [np.asarray(row, dtype=np.uint8) for row in ref_synx_rows] + ref_synz_list = [np.asarray(row, dtype=np.uint8) for row in ref_synz_rows] + ref_final = np.asarray(ref_final_row, dtype=np.uint8) + result_dict = _run_gate_backend_result_dict( + sample_backend=sample_backend, + distance=distance, + basis=basis, + physical_error_rate=physical_error_rate, + total_rounds=total_rounds, + num_shots=num_shots, + seed=seed, + p1_scale=p1_scale, + p_meas_scale=p_meas_scale, + p_prep_scale=p_prep_scale, + ) + + synx_rows = _result_rows_for_key(result_dict, "synx") + synz_rows = _result_rows_for_key(result_dict, "synz") + final_rows = _result_rows_for_key(result_dict, "final") + + if len(synx_rows) != num_shots or len(synz_rows) != num_shots or len(final_rows) != num_shots: + msg = ( + "Result register lengths do not match the requested shot count: " + f"synx={len(synx_rows)}, synz={len(synz_rows)}, final={len(final_rows)}, shots={num_shots}" + ) + raise ValueError( + msg, + ) + + for shot_idx in range(num_shots): + synx_list = _reshape_round_values(synx_rows[shot_idx], total_rounds, num_x_stab, "synx") + synz_list = _reshape_round_values(synz_rows[shot_idx], total_rounds, num_z_stab, "synz") + final = np.asarray(final_rows[shot_idx], dtype=np.uint8) + + if final.size != patch.geometry.num_data: + msg = f"Register 'final' has {final.size} bits for one shot, expected {patch.geometry.num_data}" + raise ValueError( + msg, + ) + + # Decode relative to the noiseless gate-level baseline so the native + # DEM sees deviations from the actual circuit trajectory. + synx_list = [ + np.asarray(synx, dtype=np.uint8) ^ ref_synx + for synx, ref_synx in zip(synx_list, ref_synx_list, strict=True) + ] + synz_list = [ + np.asarray(synz, dtype=np.uint8) ^ ref_synz + for synz, ref_synz in zip(synz_list, ref_synz_list, strict=True) + ] + final = final ^ ref_final + + raw_parity = int(sum(int(final[q]) for q in logical_qubits) % 2) + if num_raw_errors is None: + msg = "Gate-level backends must track raw parity counts" + raise RuntimeError(msg) + num_raw_errors += raw_parity + + if basis.upper() == "Z": + is_error, _ = decoder.decode_memory_z(synx_list, synz_list, final) + else: + is_error, _ = decoder.decode_memory_x(synx_list, synz_list, final) + num_logical_errors += int(is_error) + elif sample_backend == "native_sampler": + native_runtime = _native_sampler_runtime( + distance, + total_rounds, + basis, + physical_error_rate, + dem_mode, + native_circuit_source, + decoder_type=decoder_type, + ancilla_budget=ancilla_budget, + p1_scale=p1_scale, + p_meas_scale=p_meas_scale, + p_prep_scale=p_prep_scale, + ) + sampler = native_runtime.sampler + dem_decoder = native_runtime.dem_decoder + detection_events, observable_flips = sampler.sample(num_shots=num_shots, seed=seed) + + num_raw_errors = None + # Fast path: sample+decode entirely in Rust via ObservableDecoder trait. + # The DemSampler keeps all per-shot data in Rust -- nothing crosses to Python. + dem_str_for_rust = native_runtime.dem_str + rust_sampler = getattr(sampler, "sampler", None) + if dem_str_for_rust and rust_sampler and hasattr(rust_sampler, "sample_decode_count"): + # Use parallel path for slow decoders (Tesseract, BP+OSD, etc.) + if decoder_type != "pymatching" and hasattr(rust_sampler, "sample_decode_count_parallel"): + num_logical_errors = rust_sampler.sample_decode_count_parallel( + dem_str_for_rust, + num_shots, + decoder_type, + seed, + ) + else: + num_logical_errors = rust_sampler.sample_decode_count( + dem_str_for_rust, + num_shots, + decoder_type, + seed, + ) + else: + detection_events, observable_flips = sampler.sample(num_shots=num_shots, seed=seed) + num_logical_errors = _decode_all_shots(dem_decoder, detection_events, observable_flips, num_shots) + else: + msg = f"Unknown sample backend: {sample_backend}" + raise ValueError(msg) + + logical_error_rate = num_logical_errors / num_shots if num_shots else 0.0 + raw_error_rate = None if num_raw_errors is None else (num_raw_errors / num_shots if num_shots else 0.0) + + return SweepPoint( + backend=backend_label or sample_backend, + distance=distance, + basis=basis.upper(), + physical_error_rate=physical_error_rate, + total_rounds=total_rounds, + num_shots=num_shots, + num_logical_errors=num_logical_errors, + num_raw_errors=num_raw_errors, + logical_error_rate=logical_error_rate, + raw_error_rate=raw_error_rate, + ) + + +def _fit_per_round_rate(points: list[SweepPoint]) -> float: + """Fit one per-round logical error rate to several memory durations.""" + if not points: + msg = "Need at least one point to fit a per-round logical error rate" + raise ValueError(msg) + if all(point.logical_error_rate <= 0.0 for point in points): + return 0.0 + if all(point.logical_error_rate >= 0.5 for point in points): + return 0.5 + if len(points) == 1: + point = points[0] + return ler_per_round_exp(point.logical_error_rate, point.total_rounds) + + def objective(per_round_rate: float) -> float: + return sum( + (ler_over_rounds(per_round_rate, point.total_rounds) - point.logical_error_rate) ** 2 for point in points + ) + + left = 0.0 + right = 0.5 - 1e-12 # exclusive upper bound: per-round rate must be strictly below 0.5 + phi = (1.0 + math.sqrt(5.0)) / 2.0 + inv_phi = 1.0 / phi + c = right - (right - left) * inv_phi + d = left + (right - left) * inv_phi + fc = objective(c) + fd = objective(d) + + for _ in range(96): + if fc <= fd: + right = d + d = c + fd = fc + c = right - (right - left) * inv_phi + fc = objective(c) + else: + left = c + c = d + fc = fd + d = left + (right - left) * inv_phi + fd = objective(d) + + return 0.5 * (left + right) + + +def _fit_summary_from_points(points: list[SweepPoint]) -> FitSummary: + """Fit a per-round logical rate for one ``(d, basis, p)`` group.""" + if not points: + msg = "Cannot summarize an empty point group" + raise ValueError(msg) + + ordered = sorted(points, key=lambda point: point.total_rounds) + first = ordered[0] + fitted_per_round = _fit_per_round_rate(ordered) + per_round_ci_low, per_round_ci_high, projected_ci_low, projected_ci_high = _fit_summary_confidence_intervals( + ordered, + ) + residuals = [ler_over_rounds(fitted_per_round, point.total_rounds) - point.logical_error_rate for point in ordered] + rms_error = math.sqrt(sum(residual * residual for residual in residuals) / len(residuals)) + logical_rate_intervals = [_wilson_interval(point.num_logical_errors, point.num_shots) for point in ordered] + return FitSummary( + backend=first.backend, + distance=first.distance, + basis=first.basis, + physical_error_rate=first.physical_error_rate, + num_shots_per_round_point=first.num_shots, + round_values=tuple(point.total_rounds for point in ordered), + observed_logical_error_rates=tuple(point.logical_error_rate for point in ordered), + observed_raw_error_rates=tuple(point.raw_error_rate for point in ordered), + fitted_logical_error_rate_per_round=fitted_per_round, + fitted_projected_logical_error_rate_over_d_rounds=ler_over_rounds(fitted_per_round, first.distance), + fit_root_mean_square_error=rms_error, + observed_logical_error_counts=tuple(point.num_logical_errors for point in ordered), + observed_logical_error_rate_lower_bounds=tuple(interval[0] for interval in logical_rate_intervals), + observed_logical_error_rate_upper_bounds=tuple(interval[1] for interval in logical_rate_intervals), + fitted_logical_error_rate_per_round_ci_low=per_round_ci_low, + fitted_logical_error_rate_per_round_ci_high=per_round_ci_high, + fitted_projected_logical_error_rate_over_d_rounds_ci_low=projected_ci_low, + fitted_projected_logical_error_rate_over_d_rounds_ci_high=projected_ci_high, + ) + + +def _fit_rms_warning_text(summary: FitSummary) -> str: + """Return a warning string when the fit residual dwarfs the fitted quantity. + + When ``fit_root_mean_square_error`` is at least the fitted per-round rate + itself, the fit is dominated by statistical noise and the reported + ``fit_epsilon`` should not be trusted. Empty string means "no warning". + Skips the degenerate cases where every observed rate is 0 or >= 0.5. + """ + epsilon = summary.fitted_logical_error_rate_per_round + if epsilon <= 0.0 or epsilon >= 0.5: + return "" + if summary.fit_root_mean_square_error < epsilon: + return "" + return ( + f"WARNING: fit_rms ({summary.fit_root_mean_square_error:.3e}) " + f">= fit_epsilon ({epsilon:.3e}); fit is noise-dominated, increase --shots" + ) + + +def _linear_regression(xs: list[float], ys: list[float]) -> tuple[float, float]: + """Return ``(slope, intercept)`` for a least-squares line fit.""" + if len(xs) != len(ys): + msg = "xs and ys must have the same length" + raise ValueError(msg) + if len(xs) < 2: + msg = "Need at least two points for linear regression" + raise ValueError(msg) + + x_mean = statistics.fmean(xs) + y_mean = statistics.fmean(ys) + ss_xx = sum((x - x_mean) ** 2 for x in xs) + if ss_xx <= 0.0: + msg = "Linear regression requires at least two distinct x values" + raise ValueError(msg) + ss_xy = sum((x - x_mean) * (y - y_mean) for x, y in zip(xs, ys, strict=True)) + slope = ss_xy / ss_xx + intercept = y_mean - slope * x_mean + return slope, intercept + + +def _fit_distance_scaling_at_fixed_p(summaries: list[FitSummary]) -> DistanceScalingFitSummary | None: + """Fit the standard below-threshold ansatz across distance at one fixed ``p``. + + Requires at least three distinct distances -- fitting a line through two + points is a tautology (``log_rmse == 0`` always) and the reported threshold + has no meaning. + """ + usable = sorted( + [summary for summary in summaries if summary.fitted_logical_error_rate_per_round > 0.0], + key=lambda summary: summary.distance, + ) + if len({summary.distance for summary in usable}) < 3: + return None + + xs = [0.5 * (summary.distance + 1) for summary in usable] + ys = [math.log(summary.fitted_logical_error_rate_per_round) for summary in usable] + slope, intercept = _linear_regression(xs, ys) + residuals = [y - (slope * x + intercept) for x, y in zip(xs, ys, strict=True)] + rmse = math.sqrt(sum(residual * residual for residual in residuals) / len(residuals)) + physical_error_rate = usable[0].physical_error_rate + suppression_factor = math.exp(-slope) + threshold = physical_error_rate * suppression_factor + return DistanceScalingFitSummary( + backend=usable[0].backend, + basis=usable[0].basis, + physical_error_rate=physical_error_rate, + distances=tuple(summary.distance for summary in usable), + fitted_prefactor=math.exp(intercept), + fitted_threshold=threshold, + fitted_suppression_factor=suppression_factor, + fit_root_mean_square_log_error=rmse, + ) + + +def _fit_global_scaling_law(summaries: list[FitSummary]) -> GlobalScalingFitSummary | None: + """Fit ``epsilon ~= A * (p / p_th) ** ((d + 1) / 2)`` across all ``(d, p)`` points. + + Requires at least three ``(d, p)`` points -- two points fit two parameters + perfectly (``log_rmse == 0`` always) so the reported threshold is tautological. + """ + usable = [summary for summary in summaries if summary.fitted_logical_error_rate_per_round > 0.0] + if len(usable) < 3: + return None + + xs = [0.5 * (summary.distance + 1) for summary in usable] + zs = [ + math.log(summary.fitted_logical_error_rate_per_round) - x * math.log(summary.physical_error_rate) + for summary, x in zip(usable, xs, strict=True) + ] + slope, intercept = _linear_regression(xs, zs) + threshold = math.exp(-slope) + residuals = [] + for summary in usable: + x = 0.5 * (summary.distance + 1) + predicted = intercept + x * (math.log(summary.physical_error_rate) - math.log(threshold)) + residuals.append(math.log(summary.fitted_logical_error_rate_per_round) - predicted) + rmse = math.sqrt(sum(residual * residual for residual in residuals) / len(residuals)) + return GlobalScalingFitSummary( + backend=usable[0].backend, + basis=usable[0].basis, + distances=tuple(sorted({summary.distance for summary in usable})), + physical_error_rates=tuple(sorted({summary.physical_error_rate for summary in usable})), + fitted_prefactor=math.exp(intercept), + fitted_threshold=threshold, + fit_root_mean_square_log_error=rmse, + ) + + +def _fit_per_distance_power_law( + summaries: list[FitSummary], + *, + max_physical_error_rate: float | None = None, +) -> list[PerDistancePowerLawFitSummary]: + """Fit ``epsilon_d(p) ~= C_d * p ** beta_d`` independently for each distance. + + The power law only holds below threshold -- including p values near or + above threshold systematically pulls the fitted exponent down from its + true below-threshold value. Callers that have an estimated threshold + should pass ``max_physical_error_rate=p_th`` (or a fraction of it) so + only the sub-threshold regime is fit. + + Also returns the OLS standard error of the slope so callers can display + uncertainty alongside the exponent. + """ + fits: list[PerDistancePowerLawFitSummary] = [] + for distance in sorted({summary.distance for summary in summaries}): + rows = sorted( + [ + summary + for summary in summaries + if summary.distance == distance + and summary.fitted_logical_error_rate_per_round > 0.0 + and (max_physical_error_rate is None or summary.physical_error_rate <= max_physical_error_rate) + ], + key=lambda summary: summary.physical_error_rate, + ) + if len(rows) < 2: + continue + xs = [math.log(summary.physical_error_rate) for summary in rows] + ys = [math.log(summary.fitted_logical_error_rate_per_round) for summary in rows] + slope, intercept = _linear_regression(xs, ys) + residuals = [y - (slope * x + intercept) for x, y in zip(xs, ys, strict=True)] + rmse = math.sqrt(sum(residual * residual for residual in residuals) / len(residuals)) + # Standard error of the OLS slope: sqrt(residual_var / sum((x - x_mean)^2)), + # where residual_var has Bessel correction (n - 2) for the two fitted parameters. + n_points = len(rows) + x_mean = sum(xs) / n_points + ss_xx = sum((x - x_mean) ** 2 for x in xs) + if n_points > 2 and ss_xx > 0.0: + residual_variance = sum(r * r for r in residuals) / (n_points - 2) + slope_std_error = math.sqrt(residual_variance / ss_xx) + else: + slope_std_error = 0.0 + fits.append( + PerDistancePowerLawFitSummary( + backend=rows[0].backend, + basis=rows[0].basis, + distance=distance, + physical_error_rates=tuple(summary.physical_error_rate for summary in rows), + fitted_prefactor=math.exp(intercept), + fitted_exponent=slope, + expected_distance_scaling_exponent=0.5 * (distance + 1), + fit_root_mean_square_log_error=rmse, + fitted_exponent_std_error=slope_std_error, + ), + ) + return fits + + +def _fit_fss_threshold( + summaries: list[FitSummary], + *, + seed_threshold: float | None = None, + seed_nu: float = 1.0, + window_factor_low: float = 0.55, + window_factor_high: float = 1.5, +) -> FSSThresholdFitSummary | None: + """Fit the Wang-Harrington-Preskill polynomial FSS form to ``summaries``. + + Uses ``pecos.analysis.threshold_curve.threshold_fit`` with the default + ``func`` (``p_L = a + b*x + c*x**2`` with ``x = (p - p_th) * d**(1/nu)``). + The polynomial expansion is only accurate near threshold, so points are + filtered to the window ``[window_factor_low, window_factor_high] * seed_threshold`` + before fitting. ``seed_threshold`` defaults to the per-round-rate crossing + estimate from ``_estimate_threshold``. Returns ``None`` when the estimator + cannot seed, too few points remain in the window, or ``curve_fit`` raises. + """ + if not summaries: + return None + + if seed_threshold is None: + seed_threshold = _estimate_threshold(summaries) + if seed_threshold is None or seed_threshold <= 0.0: + return None + + low = seed_threshold * window_factor_low + high = seed_threshold * window_factor_high + windowed = [ + summary + for summary in summaries + if low <= summary.physical_error_rate <= high and summary.fitted_logical_error_rate_per_round > 0.0 + ] + if len({summary.distance for summary in windowed}) < 2 or len(windowed) < 5: + return None + + plist = [summary.physical_error_rate for summary in windowed] + dlist = [summary.distance for summary in windowed] + plog = [summary.fitted_logical_error_rate_per_round for summary in windowed] + mean_plog = sum(plog) / len(plog) + initial = [seed_threshold, seed_nu, mean_plog, 1.0, 1.0] + + try: + from pecos.analysis.threshold_curve import func as _fss_func + from pecos.analysis.threshold_curve import threshold_fit as _fss_threshold_fit + except ImportError: + return None + + try: + popt, stdev = _fss_threshold_fit(plist, dlist, plog, _fss_func, initial) + except Exception: # pragma: no cover - scipy fit can fail many ways on bad data + return None + + p_th, nu, a, b, c = (float(popt[i]) for i in range(5)) + p_th_se, nu_se, a_se, b_se, c_se = (float(stdev[i]) for i in range(5)) + if p_th <= 0.0 or nu <= 0.0: + # Non-physical fit result -- treat as failure so callers can fall back. + return None + + first = windowed[0] + return FSSThresholdFitSummary( + backend=first.backend, + basis=first.basis, + p_th=p_th, + p_th_std_error=p_th_se, + nu=nu, + nu_std_error=nu_se, + coeff_a=a, + coeff_a_std_error=a_se, + coeff_b=b, + coeff_b_std_error=b_se, + coeff_c=c, + coeff_c_std_error=c_se, + num_points=len(windowed), + fit_window_low=low, + fit_window_high=high, + ) + + +def _estimate_threshold( + summaries: list[FitSummary], + *, + metric: str = "fitted_logical_error_rate_per_round", +) -> float | None: + """Estimate the ``p`` where the smallest- and largest-distance curves cross. + + Defaults to the canonical threshold definition -- crossing of + ``fitted_logical_error_rate_per_round``, independent of code distance at + threshold. Pass ``metric="fitted_projected_logical_error_rate_over_d_rounds"`` + to instead find the crossing on the ``d``-scaled metric, which lies at a + different (lower) ``p`` because that metric itself scales with ``d``. + """ + if not summaries: + return None + + distances = sorted({summary.distance for summary in summaries}) + if len(distances) < 2: + return None + + d_small = distances[0] + d_large = distances[-1] + by_key = {(summary.distance, summary.physical_error_rate): summary for summary in summaries} + error_rates = sorted({summary.physical_error_rate for summary in summaries}) + + diffs: list[tuple[float, float]] = [] + for p in error_rates: + small = by_key.get((d_small, p)) + large = by_key.get((d_large, p)) + if small is None or large is None: + continue + diffs.append((p, getattr(large, metric) - getattr(small, metric))) + + for (p0, diff0), (p1, diff1) in itertools.pairwise(diffs): + if diff0 == 0.0: + return p0 + if diff0 * diff1 < 0.0: + t = abs(diff0) / (abs(diff0) + abs(diff1)) + return math.exp((1.0 - t) * math.log(p0) + t * math.log(p1)) + return None + + +def _suppression_summary(summaries: list[FitSummary]) -> list[tuple[float, bool]]: + """Check whether fitted projected ``d``-round rates decrease with distance.""" + distances = sorted({summary.distance for summary in summaries}) + error_rates = sorted({summary.physical_error_rate for summary in summaries}) + by_key = {(summary.distance, summary.physical_error_rate): summary for summary in summaries} + + rows: list[tuple[float, bool]] = [] + for p in error_rates: + available = [by_key[(d, p)] for d in distances if (d, p) in by_key] + if len(available) < 2: + continue + ordered = [s.fitted_projected_logical_error_rate_over_d_rounds for s in available] + rows.append((p, all(next_value < value for value, next_value in itertools.pairwise(ordered)))) + return rows + + +def _distance_scaling_fits(summaries: list[FitSummary]) -> list[DistanceScalingFitSummary]: + """Fit the distance-scaling ansatz separately at each physical error rate.""" + error_rates = sorted({summary.physical_error_rate for summary in summaries}) + fits: list[DistanceScalingFitSummary] = [] + for physical_error_rate in error_rates: + fit = _fit_distance_scaling_at_fixed_p( + [summary for summary in summaries if summary.physical_error_rate == physical_error_rate], + ) + if fit is not None: + fits.append(fit) + return fits + + +def _pairwise_lambda_ratios(summaries: list[FitSummary]) -> list[PairwiseLambdaSummary]: + """Compute empirical ``Lambda_{d/(d+2)}`` ratios from fitted per-round rates.""" + distances = sorted({summary.distance for summary in summaries}) + error_rates = sorted({summary.physical_error_rate for summary in summaries}) + by_key = {(summary.distance, summary.physical_error_rate): summary for summary in summaries} + + ratios: list[PairwiseLambdaSummary] = [] + for physical_error_rate in error_rates: + for distance_low, distance_high in itertools.pairwise(distances): + low = by_key.get((distance_low, physical_error_rate)) + high = by_key.get((distance_high, physical_error_rate)) + if low is None or high is None: + continue + if low.fitted_logical_error_rate_per_round <= 0.0 or high.fitted_logical_error_rate_per_round <= 0.0: + continue + ratios.append( + PairwiseLambdaSummary( + backend=low.backend, + basis=low.basis, + physical_error_rate=physical_error_rate, + distance_low=distance_low, + distance_high=distance_high, + lambda_d_over_d_plus_2=( + low.fitted_logical_error_rate_per_round / high.fitted_logical_error_rate_per_round + ), + ), + ) + return ratios + + +def _print_basis_table(summaries: list[FitSummary], *, metric: str, title: str) -> None: + """Print a compact table for one basis and one fitted metric.""" + distances = sorted({summary.distance for summary in summaries}) + error_rates = sorted({summary.physical_error_rate for summary in summaries}) + by_key = {(summary.distance, summary.physical_error_rate): summary for summary in summaries} + + print() + print(title) + print("p".ljust(10) + "".join(f"d={distance}".rjust(14) for distance in distances)) + print("-" * (10 + 14 * len(distances))) + + for p in error_rates: + row = [f"{p:<10.5g}"] + for distance in distances: + summary = by_key.get((distance, p)) + if summary is None: + row.append(f"{'--':>14}") + else: + row.append(f"{getattr(summary, metric):>14.6e}") + print("".join(row)) + + +def _resolve_output_dir(output_dir: str | None, *, wants_outputs: bool) -> Path | None: + """Choose where optional artifacts should be written.""" + if not wants_outputs: + return None + if output_dir is not None: + path = Path(output_dir).expanduser().resolve() + path.mkdir(parents=True, exist_ok=True) + return path + return Path(tempfile.mkdtemp(prefix="pecos_surface_threshold_")) + + +def _basis_summary(summaries: list[FitSummary]) -> dict[str, Any]: + """Create a compact JSON-friendly summary for one basis.""" + distance_scaling = _distance_scaling_fits(summaries) + global_scaling = _fit_global_scaling_law(summaries) + power_law_fits = _fit_per_distance_power_law(summaries) + lambda_ratios = _pairwise_lambda_ratios(summaries) + return { + "per_distance_power_law_fits": [asdict(fit) for fit in power_law_fits], + "pairwise_lambda_ratios": [asdict(ratio) for ratio in lambda_ratios], + "fixed_p_distance_scaling_fits": [ + { + "backend": fit.backend, + "basis": fit.basis, + "physical_error_rate": fit.physical_error_rate, + "distances": fit.distances, + "fitted_prefactor": fit.fitted_prefactor, + "fitted_lambda_d_over_d_plus_2": fit.fitted_suppression_factor, + "fit_root_mean_square_log_error": fit.fit_root_mean_square_log_error, + "background_implied_threshold": fit.fitted_threshold, + } + for fit in distance_scaling + ], + "suppression": [ + { + "physical_error_rate": p, + "is_suppressed": is_suppressed, + } + for p, is_suppressed in _suppression_summary(summaries) + ], + "background_threshold_crossing": _estimate_threshold(summaries), + "background_threshold_crossing_per_round": _estimate_threshold( + summaries, + metric="fitted_logical_error_rate_per_round", + ), + "background_threshold_crossing_d_rounds": _estimate_threshold( + summaries, + metric="fitted_projected_logical_error_rate_over_d_rounds", + ), + "background_threshold_style_global_scaling_fit": None if global_scaling is None else asdict(global_scaling), + } + + +def _timing_summary(point_timings: list[dict[str, Any]], *, total_wall_clock_seconds: float) -> dict[str, Any]: + """Aggregate end-to-end sweep timings in a user-facing way.""" + + def aggregate(rows: list[dict[str, Any]]) -> dict[str, float | int]: + total_seconds = sum(float(row["elapsed_seconds"]) for row in rows) + total_shots = sum(int(row["num_shots"]) for row in rows) + return { + "seconds": total_seconds, + "shots": total_shots, + "shots_per_second": (total_shots / total_seconds) if total_seconds > 0.0 else 0.0, + } + + backends = sorted({str(row["backend"]) for row in point_timings}) + bases = sorted({str(row["basis"]) for row in point_timings}) + + per_backend = { + backend: aggregate([row for row in point_timings if row["backend"] == backend]) for backend in backends + } + per_basis = {basis: aggregate([row for row in point_timings if row["basis"] == basis]) for basis in bases} + per_backend_basis = { + backend: { + basis: aggregate( + [row for row in point_timings if row["backend"] == backend and row["basis"] == basis], + ) + for basis in bases + if any(row["backend"] == backend and row["basis"] == basis for row in point_timings) + } + for backend in backends + } + + return { + "total_wall_clock_seconds": total_wall_clock_seconds, + "total_point_seconds": sum(float(row["elapsed_seconds"]) for row in point_timings), + "total_points": len(point_timings), + "total_shots": sum(int(row["num_shots"]) for row in point_timings), + "overall_shots_per_second": ( + sum(int(row["num_shots"]) for row in point_timings) / total_wall_clock_seconds + if total_wall_clock_seconds > 0.0 + else 0.0 + ), + "per_backend": per_backend, + "per_basis": per_basis, + "per_backend_basis": per_backend_basis, + } + + +def _print_timing_summary(timing_summary: dict[str, Any]) -> None: + """Print a compact end-to-end timing summary.""" + print() + print("Timing Summary") + print(f" total wall clock : {timing_summary['total_wall_clock_seconds']:.3f}s") + print(f" total point time : {timing_summary['total_point_seconds']:.3f}s") + print(f" total points : {timing_summary['total_points']}") + print(f" total shots : {timing_summary['total_shots']}") + print(f" overall throughput: {timing_summary['overall_shots_per_second']:.3f} shots/s") + + print(" by backend:") + for backend, entry in timing_summary["per_backend"].items(): + print( + f" {backend}: {entry['seconds']:.3f}s over {entry['shots']} shots " + f"({entry['shots_per_second']:.3f} shots/s)", + ) + + print(" by basis:") + for basis, entry in timing_summary["per_basis"].items(): + print( + f" {basis}: {entry['seconds']:.3f}s over {entry['shots']} shots " + f"({entry['shots_per_second']:.3f} shots/s)", + ) + + print(" by backend+basis:") + for backend, basis_rows in timing_summary["per_backend_basis"].items(): + basis_text = ", ".join( + f"{basis}={entry['seconds']:.3f}s/{entry['shots']} shots" for basis, entry in basis_rows.items() + ) + print(f" {backend}: {basis_text}") + + +def _write_json_results( + output_path: Path, + *, + args: argparse.Namespace, + points: list[SweepPoint], + summaries: list[FitSummary], + point_timings: list[dict[str, Any]], + timing_summary: dict[str, Any], +) -> None: + """Write sweep results to a JSON artifact.""" + bases = sorted({summary.basis for summary in summaries}) + payload = { + "config": { + "distances": sorted(set(args.distances)), + "bases": bases, + "sample_backend_mode": args.sample_backend, + "executed_backends": sorted({point.backend for point in points}), + "duration_multipliers": sorted(set(args.duration_multipliers)), + "duration_min_multiplier": args.duration_min_multiplier, + "duration_max_multiplier": args.duration_max_multiplier, + "duration_num_points": args.duration_num_points, + "duration_schedule_description": args.duration_schedule_description, + "duration_rounds_by_distance": { + str(distance): list(rounds) for distance, rounds in sorted(args.duration_rounds_by_distance.items()) + }, + "error_rates": sorted(set(args.error_rates)), + "shots": args.shots, + "dem_mode": args.dem_mode, + "native_circuit_source": args.native_circuit_source, + "seed": args.seed, + "backend_runtime_descriptions": { + backend: _backend_runtime_label(backend, args.native_circuit_source) + for backend in sorted({point.backend for point in points}) + }, + "noise_model": _noise_model_description(args), + "fit_model": "p_L(r) = 0.5 * (1 - (1 - 2 * epsilon) ** r)", + "primary_power_law_model": "epsilon_d(p) ~= A_d * p ** c_d", + "primary_lambda_model": "Lambda_{d/(d+2)}(p) = epsilon_d(p) / epsilon_{d+2}(p)", + "background_distance_scaling_model": "epsilon ~= A * (p / p_th)^((d + 1) / 2)", + }, + "points": [asdict(point) for point in points], + "point_timings": point_timings, + "fit_summaries": [asdict(summary) for summary in summaries], + "timing_summary": timing_summary, + "summary": { + backend: { + basis: _basis_summary( + [summary for summary in summaries if summary.backend == backend and summary.basis == basis], + ) + for basis in bases + } + for backend in sorted({summary.backend for summary in summaries}) + }, + } + output_path.write_text(json.dumps(payload, indent=2, sort_keys=True) + "\n") + + +def _require_matplotlib_pyplot() -> ModuleType: + """Return ``matplotlib.pyplot``, raising a clear error if it is not installed.""" + try: + import matplotlib.pyplot as plt + except ImportError as exc: # pragma: no cover + msg = "matplotlib is required to render plot output (install matplotlib)" + raise RuntimeError(msg) from exc + return plt + + +# Shared palette used by every plot writer so colors are consistent across the +# duration overlay, per-round overlay, and per-basis curves. Indexed by distance. +_DISTANCE_COLOR_PALETTE: list[str] = [ + "#2563eb", # blue + "#dc2626", # red + "#059669", # green + "#9333ea", # purple + "#ea580c", # orange + "#0f766e", # teal +] + + +def _color_for_distance(distance_index: int) -> str: + """Return the palette color for the ``distance_index``-th distance (wraps if needed).""" + return _DISTANCE_COLOR_PALETTE[distance_index % len(_DISTANCE_COLOR_PALETTE)] + + +def _color_by_distance(distances: list[int]) -> dict[int, str]: + """Return a mapping from each distance to its palette color.""" + return {distance: _color_for_distance(index) for index, distance in enumerate(distances)} + + +def _format_rate_for_filename(value: float) -> str: + """Render a rate in a filename-friendly compact form.""" + return f"{value:.6g}".replace(".", "p") + + +def _basis_linestyle(basis: str) -> str: + """Return the matplotlib line style for one basis.""" + return "-" if basis.upper() == "X" else "--" + + +def _duration_fit_curve_points( + summary: FitSummary, + *, + num_samples: int = 120, +) -> list[tuple[float, float]]: + """Return a smooth fitted duration curve for one ``(basis, distance, p)`` summary.""" + if not summary.round_values: + return [] + + min_rounds = float(min(summary.round_values)) + max_rounds = float(max(summary.round_values)) + if math.isclose(min_rounds, max_rounds): + round_samples = [min_rounds] + else: + round_samples = [ + min_rounds + (max_rounds - min_rounds) * index / (num_samples - 1) for index in range(num_samples) + ] + + return [ + ( + total_rounds / summary.distance, + ler_over_rounds(summary.fitted_logical_error_rate_per_round, total_rounds), + ) + for total_rounds in round_samples + ] + + +def _build_duration_overlay_figure( + *, + points: list[SweepPoint], + summaries: list[FitSummary], + backend: str, + physical_error_rate: float, + figsize: tuple[float, float] = (9.5, 6.5), +) -> Figure: + """Build the fixed-``p`` logical-error-vs-duration overlay figure (caller closes it).""" + plt = _require_matplotlib_pyplot() + distances = sorted({point.distance for point in points}) + bases = sorted({point.basis for point in points}) + color_by_distance = _color_by_distance(distances) + + fig, ax = plt.subplots(figsize=figsize) + summary_by_series = {(summary.basis, summary.distance): summary for summary in summaries} + for basis in bases: + for distance in distances: + series = sorted( + [point for point in points if point.basis == basis and point.distance == distance], + key=lambda point: point.total_rounds, + ) + if not series: + continue + summary = summary_by_series.get((basis, distance)) + color = color_by_distance[distance] + if summary is not None: + fit_curve = _duration_fit_curve_points(summary) + fit_xs = [curve_x for curve_x, _ in fit_curve] + fit_ys = [max(curve_y, 1e-12) for _, curve_y in fit_curve] + ax.plot( + fit_xs, + fit_ys, + linewidth=2.5, + linestyle=_basis_linestyle(basis), + color=color, + label=f"{basis} d={distance}", + ) + xs = [point.total_rounds / point.distance for point in series] + ys = [max(point.logical_error_rate, 1e-12) for point in series] + lower_bounds = [_wilson_interval(point.num_logical_errors, point.num_shots)[0] for point in series] + upper_bounds = [_wilson_interval(point.num_logical_errors, point.num_shots)[1] for point in series] + yerr_lower = [max(y - low, 0.0) for y, low in zip(ys, lower_bounds, strict=True)] + yerr_upper = [max(high - y, 0.0) for y, high in zip(ys, upper_bounds, strict=True)] + ax.errorbar( + xs, + ys, + yerr=[yerr_lower, yerr_upper], + marker="o", + linestyle="none", + color=color, + markerfacecolor="white", + markeredgecolor=color, + markeredgewidth=1.5, + elinewidth=1.2, + alpha=0.85, + capsize=3, + ) + + ax.set_title( + "Logical Memory Error vs Duration " + f"({backend}, p={physical_error_rate:.4g})\n" + "Points show observed logical error rates with 95% Wilson intervals; lines show fitted duration curves.", + ) + ax.set_xlabel("Memory duration (rounds / d)") + ax.set_ylabel("Observed logical error rate") + ax.set_yscale("log") + ax.grid(visible=True, which="both", alpha=0.25) + ax.legend(ncol=2) + fig.tight_layout() + return fig + + +def _write_duration_overlay_plot( + output_dir: Path, + stem: str, + *, + points: list[SweepPoint], + summaries: list[FitSummary], + backend: str, + physical_error_rate: float, + formats: list[str], +) -> list[Path]: + """Write one fixed-``p`` logical-error-vs-duration overlay to each requested format.""" + if not points or not formats: + return [] + plt = _require_matplotlib_pyplot() + fig = _build_duration_overlay_figure( + points=points, + summaries=summaries, + backend=backend, + physical_error_rate=physical_error_rate, + ) + output_paths = [output_dir / f"{stem}.{fmt}" for fmt in formats] + for path in output_paths: + fig.savefig(path) + plt.close(fig) + return output_paths + + +def _draw_power_law_exponents( + ax: Axes, + summaries: list[FitSummary], +) -> None: + """Annotate per-distance below-threshold power-law exponents on the plot. + + The power law ``epsilon_d(p) ~= A_d * p ** c_d`` only holds below threshold + -- including p values near or above threshold compresses the fitted + exponent toward the noise-dominated value. For each basis, this helper + estimates ``p_th`` from the per-round rate crossing, then fits only the + points with ``p <= p_th`` so the reported ``c_d`` reflects the true + below-threshold scaling (close to the theoretical ``(d + 1) / 2``). + + The annotation shows ``c_d ± se`` where ``se`` is the OLS standard error + of the slope, and notes how many points fed each fit. + """ + bases_in_data = sorted({summary.basis for summary in summaries}) + blocks: list[str] = [] + for basis in bases_in_data: + basis_summaries = [summary for summary in summaries if summary.basis == basis] + threshold = _estimate_threshold(basis_summaries) + fits = _fit_per_distance_power_law(basis_summaries, max_physical_error_rate=threshold) + if not fits: + # Fall back to fitting all points if threshold estimation fails -- + # better to show a compressed exponent than nothing. + fits = _fit_per_distance_power_law(basis_summaries) + if not fits: + continue + n_points_used = len(fits[0].physical_error_rates) if fits else 0 + pieces = [] + for fit in fits: + if fit.fitted_exponent_std_error > 0.0: + pieces.append(f"c_{fit.distance}={fit.fitted_exponent:.2f}±{fit.fitted_exponent_std_error:.2f}") + else: + pieces.append(f"c_{fit.distance}={fit.fitted_exponent:.2f}") + basis_tag = f"{basis}: " if len(bases_in_data) > 1 else "" + line = basis_tag + ", ".join(pieces) + if threshold is not None: + line += f" (fit p≤{threshold:.3g}, n={n_points_used})" + blocks.append(line) + + if not blocks: + return + + header = "Power-law fit eps_d(p) ≈ A_d · p^c_d [theory c_d=(d+1)/2]:" + text = header + "\n" + "\n".join(blocks) + ax.text( + 0.02, + 0.02, + text, + transform=ax.transAxes, + va="bottom", + ha="left", + fontsize=8.5, + color="#0f172a", + family="monospace", + bbox={"facecolor": "white", "alpha": 0.88, "edgecolor": "#cbd5e1", "boxstyle": "round,pad=0.35"}, + ) + + +def _draw_threshold_markers( + ax: Axes, + summaries: list[FitSummary], + *, + metric: str = "fitted_logical_error_rate_per_round", + label_prefix: str = "p_th", +) -> None: + """Draw a dotted grey vertical line where this metric's curves cross, per basis. + + The crossing point is computed with ``_estimate_threshold(summaries, metric=metric)`` + so the marker matches *this plot's* visual intersection rather than the canonical + per-round threshold. Callers override ``label_prefix`` (e.g. ``"p_cross"``) when + the metric is not the canonical per-round rate, to avoid implying these crossings + are all the threshold. Skipped when the estimator returns ``None``. + """ + bases_in_data = sorted({summary.basis for summary in summaries}) + # Prefer the Wang-Harrington-Preskill FSS fit (``p_th ± sigma``) for the + # canonical per-round metric. Fall back to the simpler per-curve crossing + # estimator when the FSS fit cannot converge (too few near-threshold + # points) or when the caller is plotting a non-canonical metric. + use_fss = metric == "fitted_logical_error_rate_per_round" + # Stack per-basis labels vertically so they do not overlap when two + # thresholds land near the same ``p``. Top-down in sorted basis order. + for label_row, basis in enumerate(bases_in_data): + basis_summaries = [summary for summary in summaries if summary.basis == basis] + threshold: float | None + uncertainty: float | None + fss = _fit_fss_threshold(basis_summaries) if use_fss else None + if fss is not None: + threshold = fss.p_th + uncertainty = fss.p_th_std_error + else: + threshold = _estimate_threshold(basis_summaries, metric=metric) + uncertainty = None + if threshold is None or threshold <= 0.0: + continue + ax.axvline( + threshold, + color="#334155", + linestyle=":", + linewidth=1.8, + alpha=0.7, + zorder=0, + ) + if uncertainty is not None and uncertainty > 0.0: + # Shade a +/- one-sigma band so readers can see fit uncertainty directly. + ax.axvspan( + max(threshold - uncertainty, 1e-12), + threshold + uncertainty, + color="#334155", + alpha=0.09, + zorder=0, + ) + basis_tag = f"({basis})" if len(bases_in_data) > 1 else "" + if uncertainty is not None and uncertainty > 0.0: + label = f" {label_prefix}{basis_tag}≈{threshold:.3g}±{uncertainty:.1g}" + else: + label = f" {label_prefix}{basis_tag}≈{threshold:.3g}" + ax.text( + threshold, + 0.98 - 0.045 * label_row, + label, + transform=ax.get_xaxis_transform(), + color="#334155", + alpha=0.9, + fontsize=8, + ha="left", + va="top", + ) + + +def _build_per_round_overlay_figure( + *, + summaries: list[FitSummary], + backend: str, + figsize: tuple[float, float] = (9.5, 6.5), +) -> Figure: + """Build the combined X/Z per-round-epsilon-vs-``p`` overlay figure (caller closes it).""" + plt = _require_matplotlib_pyplot() + distances = sorted({summary.distance for summary in summaries}) + bases = sorted({summary.basis for summary in summaries}) + color_by_distance = _color_by_distance(distances) + + fig, ax = plt.subplots(figsize=figsize) + for basis in bases: + for distance in distances: + series = sorted( + [summary for summary in summaries if summary.basis == basis and summary.distance == distance], + key=lambda summary: summary.physical_error_rate, + ) + if not series: + continue + xs = [summary.physical_error_rate for summary in series] + intervals = [ + _fit_summary_metric_interval(summary, "fitted_logical_error_rate_per_round") for summary in series + ] + ys = [max(value, 1e-12) for value, _, _ in intervals] + yerr_lower = [max(value - low, 0.0) for value, low, _ in intervals] + yerr_upper = [max(high - value, 0.0) for value, _, high in intervals] + ax.errorbar( + xs, + ys, + yerr=[yerr_lower, yerr_upper], + marker="o", + linewidth=2, + linestyle=_basis_linestyle(basis), + color=color_by_distance[distance], + label=f"{basis} d={distance}", + capsize=3, + ) + + ax.set_title(f"Per-round logical error rate vs p ({backend})") + ax.set_xlabel("Physical error rate p") + ax.set_ylabel("Fitted logical error rate per round") + ax.set_xscale("log") + ax.set_yscale("log") + ax.grid(visible=True, which="both", alpha=0.25) + ax.legend(ncol=2) + _draw_threshold_markers(ax, summaries) + _draw_power_law_exponents(ax, summaries) + fig.tight_layout() + return fig + + +def _write_per_round_overlay_plot( + output_dir: Path, + stem: str, + *, + summaries: list[FitSummary], + backend: str, + formats: list[str], +) -> list[Path]: + """Write the combined X/Z per-round-epsilon-vs-``p`` overlay to each requested format.""" + if not summaries or not formats: + return [] + plt = _require_matplotlib_pyplot() + fig = _build_per_round_overlay_figure(summaries=summaries, backend=backend) + output_paths = [output_dir / f"{stem}.{fmt}" for fmt in formats] + for path in output_paths: + fig.savefig(path) + plt.close(fig) + return output_paths + + +def _build_plot_figure( + *, + summaries: list[FitSummary], + metric: str, + title: str, + y_label: str, + figsize: tuple[float, float] = (9, 6), +) -> Figure: + """Build a per-basis epsilon-vs-``p`` curve figure (caller closes it).""" + plt = _require_matplotlib_pyplot() + distances = sorted({summary.distance for summary in summaries}) + error_rates = sorted({summary.physical_error_rate for summary in summaries}) + by_key = {(summary.distance, summary.physical_error_rate): summary for summary in summaries} + color_by_distance = _color_by_distance(distances) + + fig, ax = plt.subplots(figsize=figsize) + for distance in distances: + available_ps = [p for p in error_rates if (distance, p) in by_key] + if not available_ps: + continue + intervals = [_fit_summary_metric_interval(by_key[(distance, p)], metric) for p in available_ps] + ys = [max(value, 1e-12) for value, _, _ in intervals] + yerr_lower = [max(value - low, 0.0) for value, low, _ in intervals] + yerr_upper = [max(high - value, 0.0) for value, _, high in intervals] + ax.errorbar( + available_ps, + ys, + yerr=[yerr_lower, yerr_upper], + marker="o", + linewidth=2, + color=color_by_distance[distance], + label=f"d={distance}", + capsize=3, + ) + + ax.set_title(title) + ax.set_xlabel("Physical error rate p") + ax.set_ylabel(y_label) + # LER-vs-p plots read most naturally on log-log: the below-threshold + # power law eps_d(p) ~ A_d * p^c_d becomes a straight line with slope c_d, + # which matches the annotated exponents and makes crossings easy to eyeball. + ax.set_xscale("log") + ax.set_yscale("log") + ax.grid(visible=True, which="both", alpha=0.25) + ax.legend() + # Per-round rate is the canonical threshold metric -- call that crossing ``p_th``. + # The projected-over-d-rounds curves cross at a different ``p`` because the metric + # itself scales with ``d``, so we mark it but label it ``p_cross`` to be honest + # about what the line represents. + is_per_round = metric == "fitted_logical_error_rate_per_round" + _draw_threshold_markers( + ax, + summaries, + metric=metric, + label_prefix="p_th" if is_per_round else "p_cross", + ) + # Power-law fit eps_d ~= A_d * p^c_d is defined against the per-round rate, + # so annotate it only on the per-round per-basis plot. + if is_per_round: + _draw_power_law_exponents(ax, summaries) + fig.tight_layout() + return fig + + +def _write_plot( + output_dir: Path, + stem: str, + *, + summaries: list[FitSummary], + metric: str, + title: str, + y_label: str, + formats: list[str], +) -> list[Path]: + """Write a per-basis epsilon-vs-``p`` curve plot to each requested format.""" + if not summaries or not formats: + return [] + plt = _require_matplotlib_pyplot() + fig = _build_plot_figure(summaries=summaries, metric=metric, title=title, y_label=y_label) + output_paths = [output_dir / f"{stem}.{fmt}" for fmt in formats] + for path in output_paths: + fig.savefig(path) + plt.close(fig) + return output_paths + + +def _write_html_dashboard( + output_path: Path, + *, + args: argparse.Namespace, + summaries: list[FitSummary], + timing_summary: dict[str, Any], + plots: list[DashboardPlot], + json_filename: str | None, +) -> None: + """Write a simple browsable HTML report for the generated SVG artifacts.""" + from textwrap import dedent + + def meta_card(label: str, value_html: str) -> str: + return f'
{html.escape(label)}{value_html}
' + + def plot_card(plot: DashboardPlot) -> list[str]: + detail_bits = [f"backend={plot.backend}"] + if plot.basis is not None: + detail_bits.append(f"basis={plot.basis}") + if plot.physical_error_rate is not None: + detail_bits.append(f"p={plot.physical_error_rate:.4g}") + details = ", ".join(detail_bits) + image_link = html.escape(plot.filename) + title = html.escape(plot.title) + return [ + ' ", + ] + + backend_names = sorted({summary.backend for summary in summaries}) + basis_names = sorted({summary.basis for summary in summaries}) + plot_sections = [ + ("Combined Overlays", [plot for plot in plots if plot.section == "combined"]), + ("Fixed-p Duration Overlays", [plot for plot in plots if plot.section == "duration"]), + ("Per-basis Curves", [plot for plot in plots if plot.section == "basis"]), + ] + style = dedent( + """ + :root { + color-scheme: light dark; + --bg: #f8fafc; --fg: #0f172a; + --hero-bg: linear-gradient(135deg, #e0f2fe, #f8fafc 55%, #dcfce7); + --hero-border: #cbd5e1; + --card-bg: white; --card-border: #dbeafe; --card-shadow: rgba(15,23,42,0.05); + --meta-bg: rgba(255,255,255,0.82); + --muted: #475569; --link: #2563eb; --link-alt: #0369a1; + --header-border: #e2e8f0; + --img-bg: white; + } + [data-theme="dark"] { + --bg: #0f172a; --fg: #e2e8f0; + --hero-bg: linear-gradient(135deg, #1e293b, #0f172a 55%, #1a2e1a); + --hero-border: #334155; + --card-bg: #1e293b; --card-border: #334155; --card-shadow: rgba(0,0,0,0.3); + --meta-bg: rgba(30,41,59,0.82); + --muted: #94a3b8; --link: #60a5fa; --link-alt: #38bdf8; + --header-border: #334155; + --img-bg: #1e293b; + } + body { + margin: 0; + font-family: ui-sans-serif, -apple-system, BlinkMacSystemFont, sans-serif; + background: var(--bg); + color: var(--fg); + } + main { max-width: 1500px; margin: 0 auto; padding: 32px 24px 56px; } + h1, h2, h3, p { margin-top: 0; } + .theme-toggle { + position: fixed; top: 16px; right: 16px; z-index: 100; + background: var(--card-bg); border: 1px solid var(--card-border); + border-radius: 8px; padding: 6px 12px; cursor: pointer; + color: var(--fg); font-size: 0.85rem; font-weight: 600; + } + .theme-toggle:hover { opacity: 0.8; } + .hero { + background: var(--hero-bg); + border: 1px solid var(--hero-border); + border-radius: 20px; + padding: 24px; + margin-bottom: 24px; + } + .meta { + display: grid; + grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); + gap: 12px; + margin-top: 18px; + } + .meta-card { + background: var(--meta-bg); + border: 1px solid var(--card-border); + border-radius: 14px; + padding: 14px 16px; + } + .meta-card strong { + display: block; + font-size: 0.82rem; + text-transform: uppercase; + letter-spacing: 0.04em; + color: var(--muted); + margin-bottom: 6px; + } + .section { margin-top: 30px; } + .grid { + display: grid; + grid-template-columns: repeat(auto-fit, minmax(420px, 1fr)); + gap: 18px; + } + .plot-card { + background: var(--card-bg); + border: 1px solid var(--card-border); + border-radius: 18px; + overflow: hidden; + box-shadow: 0 10px 24px var(--card-shadow); + } + .plot-card header { + padding: 16px 18px 10px; + border-bottom: 1px solid var(--header-border); + } + .plot-card header p { + margin-bottom: 0; + color: var(--muted); + font-size: 0.92rem; + } + .plot-card .image-wrap { padding: 14px; background: var(--img-bg); } + .plot-card img { + width: 100%; + height: auto; + display: block; + border-radius: 12px; + background: var(--img-bg); + } + .plot-card footer { padding: 0 18px 16px; font-size: 0.92rem; } + .plot-card a { color: var(--link); text-decoration: none; font-weight: 600; } + .plot-card a:hover { text-decoration: underline; } + .links { margin-top: 14px; display: flex; flex-wrap: wrap; gap: 12px; } + .links a { color: var(--link-alt); text-decoration: none; font-weight: 600; } + .links a:hover { text-decoration: underline; } + code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; } + @media (prefers-color-scheme: dark) { + :root:not([data-theme="light"]) { + --bg: #0f172a; --fg: #e2e8f0; + --hero-bg: linear-gradient(135deg, #1e293b, #0f172a 55%, #1a2e1a); + --hero-border: #334155; + --card-bg: #1e293b; --card-border: #334155; --card-shadow: rgba(0,0,0,0.3); + --meta-bg: rgba(30,41,59,0.82); + --muted: #94a3b8; --link: #60a5fa; --link-alt: #38bdf8; + --header-border: #334155; + --img-bg: #1e293b; + } + } + """, + ).strip() + theme_script = dedent( + """ + + """, + ).strip() + distances_text = ", ".join(str(distance) for distance in sorted(set(args.distances))) + multipliers_text = getattr(args, "duration_schedule_description", None) + if not multipliers_text: + multipliers_text = ", ".join(f"{value:g}" for value in sorted(set(args.duration_multipliers))) + rounds_by_distance = getattr(args, "duration_rounds_by_distance", {}) + rounds_lines = [ + f"d={distance}: [{', '.join(str(value) for value in rounds)}]" + for distance, rounds in sorted(rounds_by_distance.items()) + ] + # Render one distance per line; html-escape each line individually since we + # join with literal
markup that must not itself be escaped. + rounds_html = "
".join(html.escape(line) for line in rounds_lines) + error_rates_text = ", ".join(f"{value:.4g}" for value in sorted(set(args.error_rates))) + + parts = [ + "", + '', + "", + ' ', + ' ', + " PECOS Surface Sweep Dashboard", + " ", + "", + "", + '', + "
", + '
', + "

PECOS Surface Sweep Dashboard

", + ( + "

This report bundles the generated SVG plots for the rotated " + "surface-code memory sweep so the run is easy to browse and compare.

" + ), + '
', + meta_card("Backends", html.escape(", ".join(backend_names))), + meta_card("Bases", html.escape(", ".join(basis_names))), + meta_card("Distances", html.escape(distances_text)), + meta_card("Round Schedule", html.escape(multipliers_text)), + meta_card("Error Rates", html.escape(error_rates_text)), + meta_card("Shots / Point", html.escape(str(args.shots))), + meta_card( + "Noise Model", + html.escape(_noise_model_description(args)), + ), + meta_card( + "Overall Throughput", + html.escape(f"{timing_summary['overall_shots_per_second']:.3f} shots/s"), + ), + meta_card("Effective Rounds", rounds_html) if rounds_html else "", + "
", + ] + if json_filename is not None: + parts.extend( + [ + '
', + f' Open JSON results', + "
", + ], + ) + parts.append("
") + + for section_title, section_plots in plot_sections: + if not section_plots: + continue + parts.extend( + [ + f'

{html.escape(section_title)}

', + '
', + ], + ) + for plot in section_plots: + parts.extend(plot_card(plot)) + parts.extend(["
", "
"]) + + parts.extend(["
", theme_script, "", ""]) + output_path.write_text("\n".join(parts) + "\n") + + +def _maybe_open_html_dashboard(output_path: Path) -> None: + """Open the generated dashboard in the default browser.""" + import webbrowser + + opened = webbrowser.open(output_path.resolve().as_uri()) + if not opened: + msg = f"Failed to open HTML dashboard at {output_path}" + raise RuntimeError(msg) + + +def load_sweep_data_from_json( + json_path: Path, +) -> tuple[list[SweepPoint], list[FitSummary], dict[str, Any]]: + """Reconstruct ``(points, fit_summaries, payload)`` from a saved JSON results file. + + Used by ``surface_sweep_report.py --render-plots`` to rebuild plots from the + canonical JSON data without rerunning the simulation. ``points`` and + ``fit_summaries`` are returned as the original frozen dataclasses, with + ``FitSummary``'s tuple fields recovered from JSON-array form. + """ + payload = json.loads(json_path.read_text()) + points = [SweepPoint(**row) for row in payload.get("points", [])] + tuple_fields = { + "round_values", + "observed_logical_error_rates", + "observed_raw_error_rates", + "observed_logical_error_counts", + "observed_logical_error_rate_lower_bounds", + "observed_logical_error_rate_upper_bounds", + } + summaries: list[FitSummary] = [] + for row in payload.get("fit_summaries", []): + kwargs = {key: (tuple(value) if key in tuple_fields else value) for key, value in row.items()} + summaries.append(FitSummary(**kwargs)) + return points, summaries, payload + + +def _merge_sweep_point_group(points: list[SweepPoint]) -> SweepPoint: + """Merge same-key SweepPoints by summing counts and recomputing rates. + + All points in the input must share the same + ``(backend, distance, basis, physical_error_rate, total_rounds)`` key. + """ + if not points: + msg = "Cannot merge an empty point group" + raise ValueError(msg) + + first = points[0] + total_shots = sum(point.num_shots for point in points) + total_logical_errors = sum(point.num_logical_errors for point in points) + raw_values = [point.num_raw_errors for point in points] + if all(value is not None for value in raw_values): + total_raw_errors: int | None = sum(v for v in raw_values if v is not None) + raw_rate: float | None = total_raw_errors / total_shots if total_shots > 0 else 0.0 + else: + total_raw_errors = None + raw_rate = None + logical_rate = total_logical_errors / total_shots if total_shots > 0 else 0.0 + return SweepPoint( + backend=first.backend, + distance=first.distance, + basis=first.basis, + physical_error_rate=first.physical_error_rate, + total_rounds=first.total_rounds, + num_shots=total_shots, + num_logical_errors=total_logical_errors, + num_raw_errors=total_raw_errors, + logical_error_rate=logical_rate, + raw_error_rate=raw_rate, + ) + + +def _merge_sweep_configs(configs: list[dict[str, Any]], source_paths: list[str]) -> dict[str, Any]: + """Merge shard configs: union list fields, keep per-shard shot detail in ``shots_per_shard``.""" + if not configs: + return {"source_shards": list(source_paths)} + + merged: dict[str, Any] = dict(configs[0]) + + for field in ("distances", "error_rates", "bases", "executed_backends"): + union: set[Any] = set() + for config in configs: + for value in config.get(field, []) or []: + union.add(value) + if union: + merged[field] = sorted(union) + + rounds_by_distance: dict[str, set[int]] = {} + for config in configs: + for distance_key, rounds in (config.get("duration_rounds_by_distance") or {}).items(): + rounds_by_distance.setdefault(str(distance_key), set()).update(int(r) for r in rounds) + if rounds_by_distance: + merged["duration_rounds_by_distance"] = { + distance_key: sorted(rounds) for distance_key, rounds in rounds_by_distance.items() + } + + shot_values = [config.get("shots") for config in configs if config.get("shots") is not None] + if len(set(shot_values)) == 1: + merged["shots"] = shot_values[0] + else: + # When shards used different per-point targets, reporting a single + # scalar would mislead readers. Record the distinct values instead. + merged["shots"] = ", ".join(str(value) for value in sorted(set(shot_values))) + + # Provenance: one row per shard with path + shots + description. + shards_metadata = [] + for path, config in zip(source_paths, configs, strict=True): + shards_metadata.append( + { + "path": path, + "shots": config.get("shots"), + "duration_schedule_description": config.get("duration_schedule_description"), + "executed_backends": config.get("executed_backends", []), + }, + ) + merged["source_shards"] = shards_metadata + + return merged + + +def _merge_sweep_timings(timings: list[dict[str, Any]]) -> dict[str, Any]: + """Sum scalar timing totals across shards; recompute throughput from totals. + + Note: ``total_wall_clock_seconds`` is the sum of each shard's wall-clock + time. When shards ran in parallel this overstates the actual elapsed time + and should be interpreted as total CPU time across shards. + """ + total_wall = sum(timing.get("total_wall_clock_seconds", 0.0) for timing in timings) + total_point = sum(timing.get("total_point_seconds", 0.0) for timing in timings) + total_shots = sum(timing.get("total_shots", 0) or 0 for timing in timings) + total_points = sum(timing.get("total_points", 0) or 0 for timing in timings) + return { + "total_wall_clock_seconds": total_wall, + "total_point_seconds": total_point, + "total_shots": total_shots, + "total_points": total_points, + "overall_shots_per_second": (total_shots / total_wall) if total_wall > 0 else 0.0, + } + + +def merge_sweep_shards( + paths: list[Path], +) -> tuple[list[SweepPoint], list[FitSummary], dict[str, Any], dict[str, Any]]: + """Load ``paths`` as sweep shards, merge points by key, re-fit, return merged data. + + Two ``SweepPoint`` entries with the same + ``(backend, distance, basis, physical_error_rate, total_rounds)`` key are + merged by summing ``num_shots`` and ``num_logical_errors`` and recomputing + the rate. ``FitSummary`` entries are re-derived from the merged points -- + not carried over from the shards -- because fit statistics depend on the + merged shot counts. + + Returns ``(merged_points, merged_summaries, merged_config, merged_timing_summary)``. + """ + if not paths: + msg = "At least one shard path is required" + raise ValueError(msg) + + all_shard_points: list[SweepPoint] = [] + shard_configs: list[dict[str, Any]] = [] + shard_timings: list[dict[str, Any]] = [] + for path in paths: + points, _summaries, payload = load_sweep_data_from_json(path) + all_shard_points.extend(points) + shard_configs.append(dict(payload.get("config", {}))) + shard_timings.append(dict(payload.get("timing_summary", {}))) + + # Group by merge key and merge each group. + point_groups: dict[tuple[str, int, str, float, int], list[SweepPoint]] = {} + for point in all_shard_points: + key = (point.backend, point.distance, point.basis, point.physical_error_rate, point.total_rounds) + point_groups.setdefault(key, []).append(point) + merged_points = [_merge_sweep_point_group(group) for group in point_groups.values()] + merged_points.sort( + key=lambda point: (point.backend, point.distance, point.basis, point.physical_error_rate, point.total_rounds), + ) + + # Re-fit: group merged points by (backend, basis, distance, p) and fit each group. + fit_groups: dict[tuple[str, str, int, float], list[SweepPoint]] = {} + for point in merged_points: + fit_groups.setdefault((point.backend, point.basis, point.distance, point.physical_error_rate), []).append( + point, + ) + merged_summaries = [ + _fit_summary_from_points(sorted(group, key=lambda point: point.total_rounds)) for group in fit_groups.values() + ] + merged_summaries.sort( + key=lambda summary: (summary.backend, summary.basis, summary.distance, summary.physical_error_rate), + ) + + merged_config = _merge_sweep_configs(shard_configs, [str(path) for path in paths]) + merged_timing = _merge_sweep_timings(shard_timings) + + return merged_points, merged_summaries, merged_config, merged_timing + + +def render_plot_artifacts( + output_dir: Path, + *, + prefix: str, + points: list[SweepPoint], + summaries: list[FitSummary], + formats: list[str], +) -> list[DashboardPlot]: + """Render every plot type from in-memory data and return the dashboard plot list. + + Used both by the live sweep (which feeds in just-collected data) and by + ``surface_sweep_report.py --render-plots`` (which feeds in data + reconstructed from a saved JSON results file). Only SVG paths get a + ``DashboardPlot`` entry, since the dashboard embeds SVG only. + """ + dashboard_plots: list[DashboardPlot] = [] + backends = sorted({summary.backend for summary in summaries}) + + def _report_written(paths: list[Path]) -> None: + for path in paths: + print(f"Wrote {path.suffix.lstrip('.').upper()} plot to {path}") + + def _svg_path_for(paths: list[Path]) -> Path | None: + return next((path for path in paths if path.suffix == ".svg"), None) + + for backend in backends: + backend_summaries = [summary for summary in summaries if summary.backend == backend] + overlay_paths = _write_per_round_overlay_plot( + output_dir, + f"{prefix}_{backend}_per_round_overlay", + summaries=backend_summaries, + backend=backend, + formats=formats, + ) + _report_written(overlay_paths) + overlay_svg = _svg_path_for(overlay_paths) + if overlay_svg is not None: + dashboard_plots.append( + DashboardPlot( + section="combined", + title=f"Per-round logical error rate vs p ({backend})", + filename=overlay_svg.name, + backend=backend, + ), + ) + + for physical_error_rate in sorted({point.physical_error_rate for point in points if point.backend == backend}): + rate_points = [ + point + for point in points + if point.backend == backend and point.physical_error_rate == physical_error_rate + ] + rate_summaries = [ + summary for summary in backend_summaries if summary.physical_error_rate == physical_error_rate + ] + stem = f"{prefix}_{backend}_p_{_format_rate_for_filename(physical_error_rate)}_duration_overlay" + duration_paths = _write_duration_overlay_plot( + output_dir, + stem, + points=rate_points, + summaries=rate_summaries, + backend=backend, + physical_error_rate=physical_error_rate, + formats=formats, + ) + _report_written(duration_paths) + duration_svg = _svg_path_for(duration_paths) + if duration_svg is not None: + dashboard_plots.append( + DashboardPlot( + section="duration", + title=f"Logical memory error vs duration ({backend}, p={physical_error_rate:.4g})", + filename=duration_svg.name, + backend=backend, + physical_error_rate=physical_error_rate, + ), + ) + + for backend in backends: + for basis in sorted({summary.basis for summary in summaries if summary.backend == backend}): + basis_summaries = [ + summary for summary in summaries if summary.backend == backend and summary.basis == basis + ] + plot_specs = [ + ( + "fitted_projected_logical_error_rate_over_d_rounds", + f"{prefix}_{backend}_{basis.lower()}_projected_d_rounds", + f"{basis}-Basis Fitted Logical Error Rate Over d Rounds ({backend})", + "Fitted logical error rate over d rounds", + ), + ( + "fitted_logical_error_rate_per_round", + f"{prefix}_{backend}_{basis.lower()}_per_round", + f"{basis}-Basis Fitted Logical Error Rate Per Round ({backend})", + "Fitted logical error rate per round", + ), + ] + for metric, stem, title, y_label in plot_specs: + plot_paths = _write_plot( + output_dir, + stem, + summaries=basis_summaries, + metric=metric, + title=title, + y_label=y_label, + formats=formats, + ) + _report_written(plot_paths) + plot_svg = _svg_path_for(plot_paths) + if plot_svg is not None: + dashboard_plots.append( + DashboardPlot( + section="basis", + title=title, + filename=plot_svg.name, + backend=backend, + basis=basis, + ), + ) + + return dashboard_plots + + +# Letter-landscape page size for every PDF report page -- matches the 11x8.5 +# aspect ratio used by cover, section dividers, and each plot page so the +# reader does not see page-size jitter when flipping through the report. +_REPORT_PAGE_SIZE: tuple[float, float] = (11.0, 8.5) + + +def _draw_meta_card( + page: Axes, + *, + x: float, + y: float, + width: float, + height: float, + label: str, + value_lines: list[str], +) -> None: + """Draw a single HTML-like meta-card (label + value block) onto the page axes. + + Long values are wrapped to fit the card width so nothing runs past the + card border. The wrap width is a conservative character-count heuristic + based on ``width`` (in figure coordinates) and the 11" report page width. + """ + import textwrap + + from matplotlib.patches import FancyBboxPatch + + card = FancyBboxPatch( + (x + 0.002, y + 0.002), + width - 0.004, + height - 0.004, + boxstyle="round,pad=0.002,rounding_size=0.012", + linewidth=1.2, + facecolor="#ffffff", + edgecolor="#dbeafe", + transform=page.transAxes, + ) + page.add_patch(card) + page.text( + x + 0.018, + y + height - 0.028, + label.upper(), + fontsize=8.5, + color="#475569", + weight="bold", + transform=page.transAxes, + ) + + # Wrap values that would otherwise overflow the card width. + page_width_inches = _REPORT_PAGE_SIZE[0] + padding_inches = 0.036 * page_width_inches # 0.018 fig-coord padding each side + # DejaVu Sans at 10.5pt averages ~0.09in per character; overestimate slightly + # so we wrap sooner rather than clip. + char_width_inches = 0.09 + usable_inches = max(0.5, width * page_width_inches - padding_inches) + max_chars = max(10, int(usable_inches / char_width_inches)) + wrapped: list[str] = [] + for line in value_lines: + if len(line) <= max_chars: + wrapped.append(line) + continue + pieces = textwrap.wrap(line, width=max_chars, break_long_words=False) or [line] + wrapped.extend(pieces) + + for offset, line in enumerate(wrapped): + page.text( + x + 0.018, + y + height - 0.06 - offset * 0.024, + line, + fontsize=10.5, + color="#0f172a", + transform=page.transAxes, + ) + + +def _build_report_cover_figure( + *, + config: dict[str, Any] | None, + summaries: list[FitSummary], + title: str = "PECOS Surface Sweep Report", +) -> Figure: + """Build a styled cover page: hero band + meta-card grid + footer timing line.""" + from matplotlib.colors import LinearSegmentedColormap + + plt = _require_matplotlib_pyplot() + fig = plt.figure(figsize=_REPORT_PAGE_SIZE, facecolor="#f8fafc") + + # Full-page axes used to position meta cards and footer text in normalized coords. + page = fig.add_axes((0.0, 0.0, 1.0, 1.0)) + page.set_xlim(0, 1) + page.set_ylim(0, 1) + page.axis("off") + page.patch.set_facecolor("#f8fafc") + + # --- Hero band with gradient + title + subtitle --- + hero = fig.add_axes((0.04, 0.74, 0.92, 0.22)) + hero.set_xticks([]) + hero.set_yticks([]) + for spine in hero.spines.values(): + spine.set_edgecolor("#cbd5e1") + spine.set_linewidth(1.0) + hero_gradient = [[column / 255.0 for column in range(256)]] + hero_cmap = LinearSegmentedColormap.from_list("pecos-hero", ["#e0f2fe", "#f8fafc", "#dcfce7"]) + hero.imshow(hero_gradient, aspect="auto", cmap=hero_cmap, extent=(0.0, 1.0, 0.0, 1.0)) + hero.text( + 0.5, + 0.62, + title, + transform=hero.transAxes, + ha="center", + va="center", + fontsize=26, + weight="bold", + color="#0f172a", + ) + hero.text( + 0.5, + 0.30, + "Rotated surface code memory experiments", + transform=hero.transAxes, + ha="center", + va="center", + fontsize=13, + color="#475569", + ) + + # --- Meta-card grid: only the scientific headline parameters. Run-level + # details (shots, timing, DEM mode, schedule, effective rounds) live in the + # appendix so this cover stays focused on what was studied. + backends_in_data = sorted({summary.backend for summary in summaries}) or ["(none)"] + bases_in_data = sorted({summary.basis for summary in summaries}) or ["(none)"] + config = config or {} + + cards: list[tuple[str, list[str], int]] = [ + ("Backends", [", ".join(backends_in_data)], 1), + ("Bases", [", ".join(bases_in_data)], 1), + ("Distances", [", ".join(str(d) for d in config.get("distances", [])) or "(none)"], 1), + ("Error Rates", [", ".join(f"{p:.4g}" for p in config.get("error_rates", [])) or "(none)"], 1), + ( + "Noise Model", + [config.get("noise_model", "depolarizing")], + 2, + ), + ] + + cols = 3 + gap = 0.015 + grid_left = 0.04 + grid_right = 0.96 + unit_width = (grid_right - grid_left - (cols - 1) * gap) / cols + card_height = 0.18 + row_y_positions = [0.50, 0.28] + col_cursor = 0 + row_cursor = 0 + for label, value_lines, span in cards: + if col_cursor + span > cols: + row_cursor += 1 + col_cursor = 0 + if row_cursor >= len(row_y_positions): + break + card_x = grid_left + col_cursor * (unit_width + gap) + card_w = unit_width * span + gap * (span - 1) + _draw_meta_card( + page, + x=card_x, + y=row_y_positions[row_cursor], + width=card_w, + height=card_height, + label=label, + value_lines=value_lines, + ) + col_cursor += span + + # --- Footer hint pointing readers at the appendix for methods/timing --- + fig.text( + 0.5, + 0.12, + "See the Appendix at the end of this report for methods, shot counts, and timing details.", + ha="center", + va="center", + fontsize=10, + color="#475569", + style="italic", + ) + + return fig + + +def _build_appendix_figure( + *, + config: dict[str, Any] | None, + timing_summary: dict[str, Any] | None, + summaries: list[FitSummary] | None = None, +) -> Figure: + """Build the "Methods and Timing" appendix page (two columns of key/value rows). + + When ``summaries`` are provided and cover enough near-threshold data, a + third section lists the Wang-Harrington-Preskill FSS fit per (backend, + basis) with fitted ``p_th`` and ``nu`` plus their standard errors. + """ + plt = _require_matplotlib_pyplot() + fig = plt.figure(figsize=_REPORT_PAGE_SIZE, facecolor="#f8fafc") + page = fig.add_axes((0.0, 0.0, 1.0, 1.0)) + page.set_xlim(0, 1) + page.set_ylim(0, 1) + page.axis("off") + page.patch.set_facecolor("#f8fafc") + + fig.text(0.5, 0.92, "Appendix: Methods and Timing", ha="center", fontsize=24, weight="bold", color="#0f172a") + fig.text( + 0.5, + 0.87, + "Run-level parameters and timing for reproducibility", + ha="center", + fontsize=12, + color="#475569", + ) + + config = config or {} + timing_summary = timing_summary or {} + + rounds_by_distance = { + int(distance): tuple(values) for distance, values in config.get("duration_rounds_by_distance", {}).items() + } + rounds_lines = [f"d={distance}: {list(rounds)}" for distance, rounds in sorted(rounds_by_distance.items())] or [ + "(no schedule recorded)", + ] + + method_rows: list[tuple[str, list[str]]] = [ + ("Shots / Point", [str(config.get("shots", "?"))]), + ("Sample Backend Mode", [str(config.get("sample_backend_mode", "(unspecified)"))]), + ("Executed Backends", [", ".join(config.get("executed_backends", [])) or "(unspecified)"]), + ("DEM Mode", [str(config.get("dem_mode", "(unspecified)"))]), + ("Native Circuit Source", [str(config.get("native_circuit_source", "(unspecified)"))]), + ("RNG Seed", [str(config.get("seed", "(unspecified)"))]), + ("Round Schedule", [str(config.get("duration_schedule_description", "(unspecified)"))]), + ("Effective Rounds", rounds_lines), + ] + + timing_rows: list[tuple[str, list[str]]] = [ + ( + "Total Wall Clock", + [f"{timing_summary.get('total_wall_clock_seconds', 0.0):.2f} s"], + ), + ("Total Shots", [str(timing_summary.get("total_shots", "?"))]), + ( + "Overall Throughput", + [f"{timing_summary.get('overall_shots_per_second', 0.0):.1f} shots/s"], + ), + ( + "Total Point Time", + [f"{timing_summary.get('total_point_seconds', 0.0):.2f} s"], + ), + ("Total Points", [str(timing_summary.get("total_points", "?"))]), + ] + + def _render_column(x: float, heading: str, rows: list[tuple[str, list[str]]]) -> None: + fig.text(x, 0.80, heading, fontsize=14, weight="bold", color="#0f172a") + page.add_patch( + _section_accent(x_left=x, x_right=x + 0.42, y=0.785), + ) + cursor = 0.75 + for label, values in rows: + fig.text(x, cursor, f"{label}:", fontsize=10.5, color="#475569", weight="bold") + for value in values: + cursor -= 0.028 + fig.text(x + 0.015, cursor, value, fontsize=10.5, color="#0f172a") + cursor -= 0.018 + + _render_column(0.08, "Methods", method_rows) + _render_column(0.54, "Timing", timing_rows) + + # --- Optional third section: FSS threshold fits per (backend, basis) --- + fss_rows = _collect_fss_fit_rows(summaries or []) + if fss_rows: + fig.text( + 0.08, + 0.36, + "Threshold Fit (Wang-Harrington-Preskill)", + fontsize=14, + weight="bold", + color="#0f172a", + ) + page.add_patch(_section_accent(x_left=0.08, x_right=0.62, y=0.345)) + fig.text( + 0.08, + 0.325, + "p_L = a + b*x + c*x^2, x = (p - p_th)*d^(1/nu) [arXiv:quant-ph/0207088]", + fontsize=9, + color="#475569", + family="monospace", + ) + # Column headers + one row per fit in a simple fixed-grid layout. + header_y = 0.29 + fig.text(0.08, header_y, "Backend", fontsize=9.5, weight="bold", color="#475569") + fig.text(0.26, header_y, "Basis", fontsize=9.5, weight="bold", color="#475569") + fig.text(0.33, header_y, "p_th", fontsize=9.5, weight="bold", color="#475569") + fig.text(0.48, header_y, "nu", fontsize=9.5, weight="bold", color="#475569") + fig.text(0.60, header_y, "n", fontsize=9.5, weight="bold", color="#475569") + fig.text(0.66, header_y, "fit window (p)", fontsize=9.5, weight="bold", color="#475569") + row_y = header_y - 0.025 + for backend, basis, fss in fss_rows: + fig.text(0.08, row_y, backend, fontsize=10, color="#0f172a") + fig.text(0.26, row_y, basis, fontsize=10, color="#0f172a") + fig.text( + 0.33, + row_y, + f"{fss.p_th:.5g} ± {fss.p_th_std_error:.2g}", + fontsize=10, + color="#0f172a", + family="monospace", + ) + fig.text( + 0.48, + row_y, + f"{fss.nu:.3g} ± {fss.nu_std_error:.2g}", + fontsize=10, + color="#0f172a", + family="monospace", + ) + fig.text(0.60, row_y, str(fss.num_points), fontsize=10, color="#0f172a", family="monospace") + fig.text( + 0.66, + row_y, + f"[{fss.fit_window_low:.4g}, {fss.fit_window_high:.4g}]", + fontsize=10, + color="#0f172a", + family="monospace", + ) + row_y -= 0.025 + + return fig + + +def _collect_fss_fit_rows( + summaries: list[FitSummary], +) -> list[tuple[str, str, FSSThresholdFitSummary]]: + """Return one ``(backend, basis, fit)`` triple per (backend, basis) that has an FSS fit.""" + rows: list[tuple[str, str, FSSThresholdFitSummary]] = [] + for backend in sorted({summary.backend for summary in summaries}): + for basis in sorted({summary.basis for summary in summaries if summary.backend == backend}): + basis_summaries = [ + summary for summary in summaries if summary.backend == backend and summary.basis == basis + ] + fit = _fit_fss_threshold(basis_summaries) + if fit is not None: + rows.append((backend, basis, fit)) + return rows + + +def _section_accent(*, x_left: float, x_right: float, y: float) -> Rectangle: + """Return the small blue accent bar drawn under an appendix column heading.""" + from matplotlib.patches import Rectangle as _Rectangle + + return _Rectangle((x_left, y), x_right - x_left, 0.003, facecolor="#2563eb", edgecolor="none") + + +def _build_section_divider_figure( + title: str, + subtitle: str | None = None, +) -> Figure: + """Build a minimal section-title page -- centered title + optional subtitle + accent bar.""" + from matplotlib.patches import Rectangle + + plt = _require_matplotlib_pyplot() + fig = plt.figure(figsize=_REPORT_PAGE_SIZE, facecolor="#f8fafc") + page = fig.add_axes((0.0, 0.0, 1.0, 1.0)) + page.set_xlim(0, 1) + page.set_ylim(0, 1) + page.axis("off") + page.patch.set_facecolor("#f8fafc") + + page.add_patch( + Rectangle( + (0.25, 0.555), + 0.5, + 0.004, + facecolor="#2563eb", + edgecolor="none", + transform=page.transAxes, + ), + ) + fig.text(0.5, 0.60, title, ha="center", va="center", fontsize=34, weight="bold", color="#0f172a") + if subtitle: + fig.text(0.5, 0.50, subtitle, ha="center", va="center", fontsize=14, color="#475569") + return fig + + +def write_pdf_report( + output_path: Path, + *, + points: list[SweepPoint], + summaries: list[FitSummary], + timing_summary: dict[str, Any] | None = None, + config: dict[str, Any] | None = None, + title: str = "PECOS Surface Sweep Report", +) -> Path: + """Write a multi-page PDF report (cover + every plot) to ``output_path``. + + The cover page lists configuration and timing; subsequent pages contain + the same plots the dashboard embeds, in the same order. Returns the + output path on success. + """ + plt = _require_matplotlib_pyplot() + from matplotlib.backends.backend_pdf import PdfPages + + backends = sorted({summary.backend for summary in summaries}) + + def _save_and_close(fig: Figure) -> None: + pdf.savefig(fig) + plt.close(fig) + + def _write_divider(section_title: str, subtitle: str | None = None) -> None: + _save_and_close(_build_section_divider_figure(section_title, subtitle)) + + with PdfPages(output_path) as pdf: + _save_and_close( + _build_report_cover_figure( + config=config, + summaries=summaries, + title=title, + ), + ) + + _write_divider("Combined Overlays", "Per-round logical error rate versus physical error rate") + for backend in backends: + backend_summaries = [summary for summary in summaries if summary.backend == backend] + _save_and_close( + _build_per_round_overlay_figure( + summaries=backend_summaries, + backend=backend, + figsize=_REPORT_PAGE_SIZE, + ), + ) + + _write_divider("Fixed-p Duration Overlays", "Logical memory error versus memory duration") + for backend in backends: + backend_summaries = [summary for summary in summaries if summary.backend == backend] + for physical_error_rate in sorted( + {point.physical_error_rate for point in points if point.backend == backend}, + ): + rate_points = [ + point + for point in points + if point.backend == backend and point.physical_error_rate == physical_error_rate + ] + rate_summaries = [ + summary for summary in backend_summaries if summary.physical_error_rate == physical_error_rate + ] + _save_and_close( + _build_duration_overlay_figure( + points=rate_points, + summaries=rate_summaries, + backend=backend, + physical_error_rate=physical_error_rate, + figsize=_REPORT_PAGE_SIZE, + ), + ) + + _write_divider("Per-basis Curves", "Fitted logical error versus physical error rate") + for backend in backends: + for basis in sorted({summary.basis for summary in summaries if summary.backend == backend}): + basis_summaries = [ + summary for summary in summaries if summary.backend == backend and summary.basis == basis + ] + plot_specs = [ + ( + "fitted_projected_logical_error_rate_over_d_rounds", + f"{basis}-Basis Fitted Logical Error Rate Over d Rounds ({backend})", + "Fitted logical error rate over d rounds", + ), + ( + "fitted_logical_error_rate_per_round", + f"{basis}-Basis Fitted Logical Error Rate Per Round ({backend})", + "Fitted logical error rate per round", + ), + ] + for metric, plot_title, y_label in plot_specs: + _save_and_close( + _build_plot_figure( + summaries=basis_summaries, + metric=metric, + title=plot_title, + y_label=y_label, + figsize=_REPORT_PAGE_SIZE, + ), + ) + + _write_divider("Appendix", "Methods and timing details") + _save_and_close( + _build_appendix_figure(config=config, timing_summary=timing_summary, summaries=summaries), + ) + + return output_path + + +def _write_artifacts( + output_dir: Path, + *, + args: argparse.Namespace, + points: list[SweepPoint], + summaries: list[FitSummary], + point_timings: list[dict[str, Any]], + timing_summary: dict[str, Any], +) -> None: + """Write any optional JSON or plot artifacts requested by the user.""" + prefix = args.output_prefix + json_filename: str | None = None + if args.save_json: + json_path = output_dir / f"{prefix}_results.json" + _write_json_results( + json_path, + args=args, + points=points, + summaries=summaries, + point_timings=point_timings, + timing_summary=timing_summary, + ) + print(f"Wrote JSON results to {json_path}") + json_filename = json_path.name + + formats: list[str] = [] + if args.save_svg: + formats.append("svg") + if args.save_pdf: + formats.append("pdf") + + dashboard_plots = render_plot_artifacts( + output_dir, + prefix=prefix, + points=points, + summaries=summaries, + formats=formats, + ) + + if args.save_html: + html_path = output_dir / f"{prefix}_dashboard.html" + _write_html_dashboard( + html_path, + args=args, + summaries=summaries, + timing_summary=timing_summary, + plots=dashboard_plots, + json_filename=json_filename, + ) + print(f"Wrote HTML dashboard to {html_path}") + if args.open_html: + _maybe_open_html_dashboard(html_path) + print(f"Opened HTML dashboard at {html_path}") + + if args.save_report_pdf: + report_path = output_dir / f"{prefix}_report.pdf" + write_pdf_report( + report_path, + points=points, + summaries=summaries, + timing_summary=timing_summary, + config=_config_for_report(args), + ) + print(f"Wrote PDF report to {report_path}") + + +def _config_for_report(args: argparse.Namespace) -> dict[str, Any]: + """Build the ``config`` dict the PDF report cover + appendix pages expect from CLI args.""" + return { + "distances": sorted(set(args.distances)), + "error_rates": sorted(set(args.error_rates)), + "shots": args.shots, + "dem_mode": getattr(args, "dem_mode", None), + "duration_schedule_description": getattr(args, "duration_schedule_description", None), + "duration_rounds_by_distance": dict(getattr(args, "duration_rounds_by_distance", {})), + # Match the key name that ``_write_json_results`` serializes so the + # appendix page can read the same field from either source. + "sample_backend_mode": getattr(args, "sample_backend", None), + "native_circuit_source": getattr(args, "native_circuit_source", None), + "decoder": getattr(args, "decoder", ["pymatching"]), + "noise_model": _noise_model_description(args), + "seed": getattr(args, "seed", None), + } + + +def _parse_args() -> argparse.Namespace: + parser = argparse.ArgumentParser(description=__doc__) + parser.add_argument("--distances", nargs="+", type=int, default=[3, 5, 7, 9], help="Odd code distances to sweep.") + parser.add_argument( + "--duration-multipliers", + "--round-multipliers", + dest="duration_multipliers", + nargs="+", + type=float, + default=None, + help=( + "Explicit duration multipliers to use for the fit, where r = multiplier * distance. " + "When omitted, the sweep uses about four evenly spaced integer round counts " + "across the default [2d, 3d] window." + ), + ) + parser.add_argument( + "--duration-min-multiplier", + type=float, + default=2.0, + help="Lower bound of the default duration window, in units of distance.", + ) + parser.add_argument( + "--duration-max-multiplier", + type=float, + default=3.0, + help="Upper bound of the default duration window, in units of distance.", + ) + parser.add_argument( + "--duration-num-points", + type=int, + default=4, + help=( + "Number of approximately evenly spaced integer round counts to sample within the " + "default duration window when --duration-multipliers is not provided." + ), + ) + parser.add_argument( + "--p1-scale", + type=float, + default=1.0 / 30.0, + help=( + "Scale factor for single-qubit gate error rate relative to p. p1 = p * p1_scale. Default: 1/30 (~0.033)." + ), + ) + parser.add_argument( + "--p-meas-scale", + type=float, + default=1.0 / 3.0, + help="Scale factor for measurement error rate. p_meas = p * p_meas_scale. Default: 1/3.", + ) + parser.add_argument( + "--p-prep-scale", + type=float, + default=1.0 / 3.0, + help="Scale factor for preparation error rate. p_prep = p * p_prep_scale. Default: 1/3.", + ) + parser.add_argument( + "--error-rates", + nargs="+", + type=float, + default=[0.001, 0.002, 0.003, 0.004, 0.005, 0.006], + help="Uniform physical error rates p to sweep.", + ) + parser.add_argument("--bases", nargs="+", default=["X", "Z"], help="Memory bases to sweep.") + parser.add_argument("--shots", type=int, default=200, help="Shots per (distance, basis, p, rounds) point.") + parser.add_argument( + "--sample-backend", + choices=[ + "sim", + "selene_sim", + "selene_stabilizer_plugin", + "native_sampler", + "compare", + "compare_gate_backends", + "compare_all", + "profile_gate_backends", + ], + default="sim", + help=( + "Sampling backend. 'sim' uses sim(Guppy(...)).classical(selene_engine()), " + "'selene_sim' uses direct selene_sim execution with Selene Stim, " + "'selene_stabilizer_plugin' uses direct selene_sim execution with the PECOS Selene StabilizerPlugin, " + "'native_sampler' uses the PECOS native DEM sampler, " + "'compare' runs sim + native_sampler, " + "'compare_gate_backends' runs selene_sim + selene_stabilizer_plugin + sim, " + "'compare_all' runs selene_sim + selene_stabilizer_plugin + sim + native_sampler, " + "and 'profile_gate_backends' reports timing breakdowns for selene_sim + " + "selene_stabilizer_plugin + sim without decoding." + ), + ) + parser.add_argument( + "--native-circuit-source", + choices=["abstract", "traced_qis"], + default="traced_qis", + help=( + "Which ideal circuit the native PECOS DEM/sampler path should analyze. " + "'traced_qis' (default) traces the lowered ideal Selene/QIS gate stream " + "(decomposed into native gates like RZZ+rotations), matching the actual " + "hardware gate set. Use this for hardware-realistic threshold estimation. " + "'abstract' uses the high-level surface TickCircuit with CX/H gates, " + "matching the standard circuit-level noise model from the QEC literature." + ), + ) + parser.add_argument( + "--dem-mode", + choices=["native_decomposed", "native_full"], + default="native_decomposed", + help="PECOS native DEM mode. PyMatching typically wants native_decomposed.", + ) + parser.add_argument( + "--decoder", + nargs="+", + choices=["pymatching", "tesseract", "bp_osd", "bp_lsd", "union_find", "relay_bp", "min_sum_bp"], + default=["pymatching"], + help=( + "Decoder(s) for circuit-level DEM decoding. Specify multiple to " + "compare them side-by-side in plots and reports. Default: pymatching. " + "Check-matrix decoders (bp_osd, bp_lsd, union_find, relay_bp, min_sum_bp) " + "extract a check matrix from the DEM automatically." + ), + ) + parser.add_argument( + "--tesseract-beam", + type=int, + default=5, + help=( + "Tesseract det_beam parameter (number of detectors to consider in beam search). " + "Default: 5 (matches upstream). With BFS orderings, det_beam=5 gives identical " + "accuracy to 50 or 100 at d<=5 while being 10x faster." + ), + ) + parser.add_argument("--seed", type=int, default=12345, help="Base RNG seed for the runtime noise model.") + parser.add_argument("--save-json", action="store_true", help="Write a JSON artifact with all sweep results.") + parser.add_argument("--save-svg", action="store_true", help="Write SVG plots for each basis and fitted metric.") + parser.add_argument( + "--save-html", + action="store_true", + help="Write an HTML dashboard that links the generated SVG plots. Implies --save-svg.", + ) + parser.add_argument( + "--open-html", + action="store_true", + help="Open the generated HTML dashboard after the run. Implies --save-html and --save-svg.", + ) + parser.add_argument( + "--save-pdf", + action="store_true", + help="Write PDF plots for each basis and fitted metric. Requires matplotlib.", + ) + parser.add_argument( + "--save-report-pdf", + action="store_true", + help=( + "Write a single multi-page PDF report (cover page with config + timing, " + "then one plot per page). Requires matplotlib." + ), + ) + parser.add_argument( + "--output-dir", + type=str, + default=None, + help="Directory for optional artifacts. Defaults to a temporary directory outside the repo.", + ) + parser.add_argument( + "--output-prefix", + type=str, + default="surface_threshold_sweep", + help="Filename prefix for optional artifacts.", + ) + parser.add_argument( + "--refine-threshold", + action="store_true", + help=( + "After the initial sweep, estimate the threshold and automatically " + "run a refined sweep with tighter error-rate spacing around it. " + "The refinement uses the same distances, bases, and shots." + ), + ) + parser.add_argument( + "--refine-window", + type=float, + default=0.5, + help=( + "Half-width of the refinement window as a fraction of the estimated " + "threshold. E.g., 0.5 means sweep from 0.5*p_th to 1.5*p_th. " + "Default: 0.5." + ), + ) + parser.add_argument( + "--refine-points", + type=int, + default=6, + help="Number of error-rate points in the refinement sweep. Default: 6.", + ) + parser.add_argument( + "--ancilla-budget", + type=int, + default=None, + help=( + "Optional cap on simultaneously live ancilla qubits. When set, the " + "circuit builder batches stabilizer measurements to stay within this " + "budget. Affects both the abstract and traced_qis circuit sources." + ), + ) + parser.add_argument( + "--benchmark-repetitions", + type=int, + default=3, + help="Timed repetitions for 'profile_gate_backends'.", + ) + parser.add_argument( + "--benchmark-warmup", + type=int, + default=1, + help="Warmup repetitions before timed runs for 'profile_gate_backends'.", + ) + return parser.parse_args() + + +_BACKEND_MODE_EXPANSIONS: dict[str, list[str]] = { + "compare": ["sim", "native_sampler"], + "compare_gate_backends": ["selene_sim", "selene_stabilizer_plugin", "sim"], + "compare_all": ["selene_sim", "selene_stabilizer_plugin", "sim", "native_sampler"], + "profile_gate_backends": ["selene_sim", "selene_stabilizer_plugin", "sim"], +} + + +def _resolve_backends(sample_backend: str, decoders: list[str] | None = None) -> list[str]: + """Resolve ``--sample-backend`` and ``--decoder`` to the concrete list of backends to run. + + When multiple decoders are given, each base backend is expanded to + ``backend:decoder`` pairs so the plotting infrastructure sees them as + separate series. With a single decoder the backend name is unchanged + for backwards compatibility. + """ + base = _BACKEND_MODE_EXPANSIONS.get(sample_backend, [sample_backend]) + if decoders is None or len(decoders) <= 1: + return base + return [f"{b}:{d}" for b in base for d in decoders] + + +def _resolve_duration_schedule( + args: argparse.Namespace, + distances: list[int], +) -> tuple[list[float], dict[int, tuple[int, ...]], str]: + """Return (multipliers, rounds-by-distance, human-readable description).""" + explicit_multipliers = None if args.duration_multipliers is None else sorted(set(args.duration_multipliers)) + if explicit_multipliers is not None: + multipliers = explicit_multipliers + description = ( + "explicit multipliers: " + + ", ".join(f"{value:g}" for value in multipliers) + + " (meaning r = multiplier * distance)" + ) + else: + multipliers = _evenly_spaced_values( + args.duration_min_multiplier, + args.duration_max_multiplier, + args.duration_num_points, + ) + description = ( + f"about {args.duration_num_points} evenly spaced round counts over " + f"[{args.duration_min_multiplier:g}d, {args.duration_max_multiplier:g}d]" + ) + rounds_by_distance = { + distance: _duration_rounds_for_distance( + distance, + explicit_multipliers=explicit_multipliers, + duration_min_multiplier=args.duration_min_multiplier, + duration_max_multiplier=args.duration_max_multiplier, + duration_num_points=args.duration_num_points, + ) + for distance in distances + } + return multipliers, rounds_by_distance, description + + +def _validate_sweep_inputs( + distances: list[int], + duration_multipliers: list[float], + args: argparse.Namespace, +) -> None: + """Raise ``ValueError`` on any invalid sweep configuration input.""" + if any(distance <= 0 or distance % 2 == 0 for distance in distances): + msg = "Distances must be positive odd integers" + raise ValueError(msg) + if any(multiplier <= 0 for multiplier in duration_multipliers): + msg = "Duration multipliers must be positive" + raise ValueError(msg) + if args.duration_min_multiplier <= 0.0 or args.duration_max_multiplier <= 0.0: + msg = "Duration window multipliers must be positive" + raise ValueError(msg) + if args.duration_max_multiplier < args.duration_min_multiplier: + msg = "duration-max-multiplier must be at least duration-min-multiplier" + raise ValueError(msg) + if args.duration_num_points <= 0: + msg = "duration-num-points must be positive" + raise ValueError(msg) + + +def _print_config_banner( + args: argparse.Namespace, + *, + backends: list[str], + distances: list[int], + bases: list[str], + error_rates: list[float], + output_dir: Path | None, + duration_schedule_description: str, + duration_rounds_by_distance: dict[int, tuple[int, ...]], +) -> None: + """Print the sweep configuration summary at the top of a run.""" + print("Native PECOS Surface Threshold Sweep") + print("=" * 40) + print(f"distances : {distances}") + print(f"bases : {bases}") + print(f"duration schedule: {duration_schedule_description}") + print( + "effective rounds : " + + "; ".join( + f"d={distance} -> {list(rounds)}" for distance, rounds in sorted(duration_rounds_by_distance.items()) + ), + ) + print(f"error rates : {error_rates}") + print(f"shots / point : {args.shots}") + print(f"sample backend mode: {args.sample_backend}") + print(f"executed backends: {backends}") + print(f"DEM mode : {args.dem_mode}") + print(f"native circuit source: {args.native_circuit_source}") + decoders = getattr(args, "decoder", ["pymatching"]) + print(f"decoder(s) : {', '.join(decoders)} via SurfaceDecoder(native PECOS DEM)") + for backend in backends: + print(f"runtime[{backend}] : {_backend_runtime_label(backend, args.native_circuit_source)}") + p1s = getattr(args, "p1_scale", 0.1) + pms = getattr(args, "p_meas_scale", 0.5) + pps = getattr(args, "p_prep_scale", 0.5) + print(f"noise model : depolarizing with p1={p1s}*p, p2=p, p_meas={pms}*p, p_prep={pps}*p") + print("fit model : p_L(r) = 0.5 * (1 - (1 - 2 * epsilon) ** r)") + if output_dir is not None: + print(f"artifact dir : {output_dir}") + + +def _parse_backend_decoder(backend: str, args: argparse.Namespace) -> tuple[str, str]: + """Split ``backend:decoder`` into base backend and decoder type. + + When a single decoder is configured the backend string has no colon + and the decoder comes from ``args.decoder[0]``. + """ + if ":" in backend: + base, decoder = backend.split(":", 1) + return base, decoder + decoders = getattr(args, "decoder", ["pymatching"]) + return backend, decoders[0] if isinstance(decoders, list) else decoders + + +def _run_one_memory_point( + args: argparse.Namespace, + *, + backend: str, + basis: str, + distance: int, + physical_error_rate: float, + total_rounds: int, + seed: int, +) -> tuple[SweepPoint, dict[str, Any]]: + """Run one sampling point, print the per-point line, return the point + its timing row.""" + base_backend, decoder_type = _parse_backend_decoder(backend, args) + point_start = time.perf_counter() + point = _run_memory_point( + sample_backend=base_backend, + distance=distance, + basis=basis, + physical_error_rate=physical_error_rate, + total_rounds=total_rounds, + num_shots=args.shots, + dem_mode=args.dem_mode, + native_circuit_source=args.native_circuit_source, + seed=seed, + decoder_type=decoder_type, + backend_label=backend, + ancilla_budget=getattr(args, "ancilla_budget", None), + p1_scale=getattr(args, "p1_scale", 0.1), + p_meas_scale=getattr(args, "p_meas_scale", 0.5), + p_prep_scale=getattr(args, "p_prep_scale", 0.5), + ) + elapsed_seconds = time.perf_counter() - point_start + naive_per_round = ler_per_round_exp(point.logical_error_rate, point.total_rounds) + print( + " " + f"LER={point.logical_error_rate:.6e} " + f"raw={_format_rate(point.raw_error_rate)} " + f"naive_per_round={naive_per_round:.6e} " + f"elapsed={elapsed_seconds:.3f}s", + ) + timing_row = { + "backend": backend, + "basis": basis, + "distance": distance, + "physical_error_rate": physical_error_rate, + "total_rounds": total_rounds, + "num_shots": args.shots, + "elapsed_seconds": elapsed_seconds, + } + return point, timing_row + + +def _fit_and_print_group( + group_points: list[SweepPoint], + backend: str, +) -> FitSummary: + """Fit one ``(backend, basis, d, p)`` group and print the fit line + any warning.""" + fit_summary = _fit_summary_from_points(group_points) + observed = ", ".join( + f"r={round_value}:{logical_rate:.3e}" + for round_value, logical_rate in zip( + fit_summary.round_values, + fit_summary.observed_logical_error_rates, + strict=True, + ) + ) + epsilon_interval = _format_interval( + fit_summary.fitted_logical_error_rate_per_round_ci_low, + fit_summary.fitted_logical_error_rate_per_round_ci_high, + fit_summary.fitted_logical_error_rate_per_round, + ) + proj_interval = _format_interval( + fit_summary.fitted_projected_logical_error_rate_over_d_rounds_ci_low, + fit_summary.fitted_projected_logical_error_rate_over_d_rounds_ci_high, + fit_summary.fitted_projected_logical_error_rate_over_d_rounds, + ) + print( + " " + f"[{backend}] " + f"fit_epsilon={fit_summary.fitted_logical_error_rate_per_round:.6e} {epsilon_interval} " + f"fit_proj_d={fit_summary.fitted_projected_logical_error_rate_over_d_rounds:.6e} {proj_interval} " + f"fit_rms={fit_summary.fit_root_mean_square_error:.3e} " + f"[{observed}]", + ) + warning_text = _fit_rms_warning_text(fit_summary) + if warning_text: + print(f" [{backend}] {warning_text}") + return fit_summary + + +def _print_cross_backend_deltas( + group_fit_summaries: dict[str, FitSummary], + backends: list[str], +) -> None: + """Print delta lines across backends in one ``(basis, d, p)`` group.""" + if "selene_sim" in group_fit_summaries: + ref_summary = group_fit_summaries["selene_sim"] + for backend in backends: + if backend == "selene_sim": + continue + summary = group_fit_summaries[backend] + delta_epsilon = ( + summary.fitted_logical_error_rate_per_round - ref_summary.fitted_logical_error_rate_per_round + ) + delta_proj_d = ( + summary.fitted_projected_logical_error_rate_over_d_rounds + - ref_summary.fitted_projected_logical_error_rate_over_d_rounds + ) + print( + " " + f"compare_vs_selene_sim[{backend}] " + f"delta_epsilon={delta_epsilon:+.3e} " + f"delta_proj_d={delta_proj_d:+.3e}", + ) + elif len(backends) == 2 and "sim" in group_fit_summaries and "native_sampler" in group_fit_summaries: + sim_summary = group_fit_summaries["sim"] + sampler_summary = group_fit_summaries["native_sampler"] + delta_epsilon = ( + sampler_summary.fitted_logical_error_rate_per_round - sim_summary.fitted_logical_error_rate_per_round + ) + delta_proj_d = ( + sampler_summary.fitted_projected_logical_error_rate_over_d_rounds + - sim_summary.fitted_projected_logical_error_rate_over_d_rounds + ) + print(f" compare delta_epsilon={delta_epsilon:+.3e} delta_proj_d={delta_proj_d:+.3e}") + + +def _run_sweep_and_fit( + args: argparse.Namespace, + *, + backends: list[str], + distances: list[int], + bases: list[str], + error_rates: list[float], + duration_rounds_by_distance: dict[int, tuple[int, ...]], +) -> tuple[list[SweepPoint], list[FitSummary], list[dict[str, Any]]]: + """Run the full sweep, fit each ``(basis, d, p)`` group, return (points, fits, timings).""" + all_points: list[SweepPoint] = [] + fit_summaries: list[FitSummary] = [] + point_timings: list[dict[str, Any]] = [] + + total_points = ( + sum(len(duration_rounds_by_distance[distance]) for distance in distances) + * len(bases) + * len(error_rates) + * len(backends) + ) + point_idx = 0 + + for basis in bases: + for distance in distances: + for physical_error_rate in error_rates: + for total_rounds in duration_rounds_by_distance[distance]: + for backend in backends: + point_idx += 1 + print( + f"[{point_idx:>3}/{total_points}] " + f"backend={backend} basis={basis} d={distance} " + f"p={physical_error_rate:.5g} r={total_rounds} ...", + ) + point, timing_row = _run_one_memory_point( + args, + backend=backend, + basis=basis, + distance=distance, + physical_error_rate=physical_error_rate, + total_rounds=total_rounds, + seed=args.seed + point_idx, + ) + all_points.append(point) + point_timings.append(timing_row) + + group_fit_summaries: dict[str, FitSummary] = {} + for backend in backends: + group_points = [ + point + for point in all_points + if point.backend == backend + and point.basis == basis + and point.distance == distance + and point.physical_error_rate == physical_error_rate + ] + fit_summary = _fit_and_print_group(group_points, backend) + fit_summaries.append(fit_summary) + group_fit_summaries[backend] = fit_summary + + _print_cross_backend_deltas(group_fit_summaries, backends) + + return all_points, fit_summaries, point_timings + + +def _print_post_sweep_analysis( + *, + backends: list[str], + bases: list[str], + distances: list[int], + fit_summaries: list[FitSummary], +) -> None: + """Print all per-basis tables, scaling fits, and threshold summaries.""" + for backend in backends: + for basis in bases: + basis_summaries = [ + summary for summary in fit_summaries if summary.backend == backend and summary.basis == basis + ] + _print_basis_table( + basis_summaries, + metric="fitted_projected_logical_error_rate_over_d_rounds", + title=f"{basis}-Basis Fitted Logical Error Rate Over d Rounds ({backend})", + ) + _print_basis_table( + basis_summaries, + metric="fitted_logical_error_rate_per_round", + title=f"{basis}-Basis Fitted Logical Error Rate Per Round ({backend})", + ) + + # Restrict to points at p <= estimated threshold so the power-law + # fit reflects the below-threshold regime where ``eps ~ A * p^c`` + # actually holds. Above threshold, curves bend and the fitted + # exponent falls away from the theoretical ``(d + 1) / 2``. + below_threshold_cut = _estimate_threshold(basis_summaries) + power_law_fits = _fit_per_distance_power_law( + basis_summaries, + max_physical_error_rate=below_threshold_cut, + ) or _fit_per_distance_power_law(basis_summaries) + if power_law_fits: + print() + cut_note = ( + f" (fit restricted to p<={below_threshold_cut:.4g})" if below_threshold_cut is not None else "" + ) + print( + f"{basis} basis [{backend}] primary epsilon_d(p) ~= A_d * p^c_d fits{cut_note}:", + ) + for fit in power_law_fits: + se_text = f" ±{fit.fitted_exponent_std_error:.3f}" if fit.fitted_exponent_std_error > 0.0 else "" + print( + " " + f"d={fit.distance}: A_d={fit.fitted_prefactor:.4g} " + f"c_d={fit.fitted_exponent:.3f}{se_text} " + f"theory=(d+1)/2={fit.expected_distance_scaling_exponent:.1f} " + f"log_rmse={fit.fit_root_mean_square_log_error:.3e} " + f"n={len(fit.physical_error_rates)}", + ) + + lambda_ratios = _pairwise_lambda_ratios(basis_summaries) + if lambda_ratios: + print(f"{basis} basis [{backend}] primary Lambda_(d/(d+2)) ratios:") + for ratio in lambda_ratios: + print( + " " + f"p={ratio.physical_error_rate:.5g}: " + f"Lambda_{{{ratio.distance_low}/{ratio.distance_high}}}=" + f"{ratio.lambda_d_over_d_plus_2:.4g}", + ) + + print(f"{basis} basis [{backend}] suppression check (fitted d-round LER decreases with distance):") + for p, is_suppressed in _suppression_summary(basis_summaries): + status = "suppressed" if is_suppressed else "not suppressed" + print(f" p={p:.5g}: {status}") + + distance_scaling_fits = _distance_scaling_fits(basis_summaries) + if distance_scaling_fits: + print(f"{basis} basis [{backend}] background fixed-p distance-scaling fits:") + for fit in distance_scaling_fits: + print( + " " + f"p={fit.physical_error_rate:.5g}: " + f"A={fit.fitted_prefactor:.4g} " + f"Lambda_(d/(d+2))={fit.fitted_suppression_factor:.4g} " + f"log_rmse={fit.fit_root_mean_square_log_error:.3e}", + ) + + crossing_per_round = _estimate_threshold( + basis_summaries, + metric="fitted_logical_error_rate_per_round", + ) + crossing_d_rounds = _estimate_threshold( + basis_summaries, + metric="fitted_projected_logical_error_rate_over_d_rounds", + ) + global_scaling_fit = _fit_global_scaling_law(basis_summaries) + # Try FSS fit seeded from both crossings; prefer d-round seed + fss_seed = crossing_d_rounds or crossing_per_round + fss_fit = _fit_fss_threshold(basis_summaries, seed_threshold=fss_seed) + if ( + crossing_per_round is not None + or crossing_d_rounds is not None + or global_scaling_fit is not None + or fss_fit is not None + ): + print(f"{basis} basis [{backend}] background threshold-style summary:") + if crossing_per_round is None and crossing_d_rounds is None: + print(f" no d={min(distances)} vs d={max(distances)} crossing was detected on this sweep.") + if crossing_per_round is not None: + print(f" per-round epsilon crossing: p ~= {crossing_per_round:.6g}") + if crossing_d_rounds is not None: + print(f" projected d-round crossing: p ~= {crossing_d_rounds:.6g}") + if global_scaling_fit is not None: + print( + " " + f"global ansatz epsilon ~= A * (p / p_th)^((d + 1) / 2): " + f"A={global_scaling_fit.fitted_prefactor:.4g} " + f"p_th={global_scaling_fit.fitted_threshold:.4g} " + f"log_rmse={global_scaling_fit.fit_root_mean_square_log_error:.3e}", + ) + if fss_fit is not None: + print( + " " + f"FSS fit p_L = a + b*x + c*x^2, x = (p - p_th) * d^(1/nu) " + f"[Wang-Harrington-Preskill, arXiv:quant-ph/0207088; " + f"window {fss_fit.fit_window_low:.4g} <= p <= {fss_fit.fit_window_high:.4g}, " + f"n={fss_fit.num_points}]:", + ) + print( + " " + f"p_th = {fss_fit.p_th:.5g} ± {fss_fit.p_th_std_error:.3g} " + f"nu = {fss_fit.nu:.4g} ± {fss_fit.nu_std_error:.3g}", + ) + + +def main() -> int: + """Run the threshold sweep CLI and optionally write summary artifacts.""" + args = _parse_args() + if args.open_html: + args.save_html = True + if args.save_html: + args.save_svg = True + + wants_outputs = args.save_json or args.save_svg or args.save_pdf or args.save_html or args.save_report_pdf + output_dir = _resolve_output_dir(args.output_dir, wants_outputs=wants_outputs) + sweep_start = time.perf_counter() + + distances = sorted(set(args.distances)) + bases = [basis.upper() for basis in args.bases] + backends = _resolve_backends(args.sample_backend, args.decoder) + duration_multipliers, duration_rounds_by_distance, duration_schedule_description = _resolve_duration_schedule( + args, + distances, + ) + error_rates = sorted(set(args.error_rates)) + + _validate_sweep_inputs(distances, duration_multipliers, args) + + args.duration_multipliers = duration_multipliers + args.duration_rounds_by_distance = duration_rounds_by_distance + args.duration_schedule_description = duration_schedule_description + + _print_config_banner( + args, + backends=backends, + distances=distances, + bases=bases, + error_rates=error_rates, + output_dir=output_dir, + duration_schedule_description=duration_schedule_description, + duration_rounds_by_distance=duration_rounds_by_distance, + ) + + if args.sample_backend == "profile_gate_backends": + _profile_gate_backends( + backends=backends, + distances=distances, + bases=bases, + error_rates=error_rates, + duration_rounds_by_distance=duration_rounds_by_distance, + shots=args.shots, + seed=args.seed, + warmup_repetitions=args.benchmark_warmup, + benchmark_repetitions=args.benchmark_repetitions, + ) + return 0 + + all_points, fit_summaries, point_timings = _run_sweep_and_fit( + args, + backends=backends, + distances=distances, + bases=bases, + error_rates=error_rates, + duration_rounds_by_distance=duration_rounds_by_distance, + ) + + _print_post_sweep_analysis( + backends=backends, + bases=bases, + distances=distances, + fit_summaries=fit_summaries, + ) + + # --- Adaptive threshold refinement --- + if args.refine_threshold: + # Estimate threshold from the initial sweep + threshold_estimates = [] + for basis in bases: + basis_summaries = [s for s in fit_summaries if s.basis == basis] + for backend in backends: + backend_summaries = [s for s in basis_summaries if s.backend == backend] + if not backend_summaries: + continue + # Use d-round crossing as initial estimate (more conservative) + crossing = _estimate_threshold( + backend_summaries, + metric="fitted_projected_logical_error_rate_over_d_rounds", + ) + if crossing is None: + # Fall back to per-round crossing + crossing = _estimate_threshold(backend_summaries) + if crossing is not None: + threshold_estimates.append((backend, basis, crossing)) + + if threshold_estimates: + # Use the median estimate across all backends/bases + median_th = sorted(t[2] for t in threshold_estimates)[len(threshold_estimates) // 2] + half_w = args.refine_window + p_low = median_th * (1.0 - half_w) + p_high = median_th * (1.0 + half_w) + n_pts = args.refine_points + import numpy as np + + refined_rates = sorted({float(f"{r:.6g}") for r in np.linspace(p_low, p_high, n_pts)}) + # Exclude rates already in the initial sweep + refined_rates = [r for r in refined_rates if r not in error_rates and r > 0] + + if refined_rates: + print() + print( + f"=== Threshold refinement: {len(refined_rates)} additional points " + f"in [{p_low:.5g}, {p_high:.5g}] around estimate p_th ~= {median_th:.5g} ===", + ) + refine_points, refine_fits, refine_timings = _run_sweep_and_fit( + args, + backends=backends, + distances=distances, + bases=bases, + error_rates=refined_rates, + duration_rounds_by_distance=duration_rounds_by_distance, + ) + # Merge with initial results + all_points.extend(refine_points) + fit_summaries.extend(refine_fits) + point_timings.extend(refine_timings) + + # Re-run analysis with merged data + print() + print("=== Combined analysis (initial + refinement) ===") + _print_post_sweep_analysis( + backends=backends, + bases=bases, + distances=distances, + fit_summaries=fit_summaries, + ) + else: + print("\n No threshold detected -- skipping refinement.") + + timing_summary = _timing_summary( + point_timings, + total_wall_clock_seconds=time.perf_counter() - sweep_start, + ) + _print_timing_summary(timing_summary) + + if output_dir is not None: + _write_artifacts( + output_dir, + args=args, + points=all_points, + summaries=fit_summaries, + point_timings=point_timings, + timing_summary=timing_summary, + ) + + return 0 + + +if __name__ == "__main__": + raise SystemExit(main()) diff --git a/examples/surface/run_full_sweep.sh b/examples/surface/run_full_sweep.sh new file mode 100755 index 000000000..10757627d --- /dev/null +++ b/examples/surface/run_full_sweep.sh @@ -0,0 +1,117 @@ +#!/bin/bash +# Run all data generation shards sequentially, then analyze and build reports. +# +# Usage: +# bash examples/surface/run_full_sweep.sh +# bash examples/surface/run_full_sweep.sh --output-dir ~/Repos/pecos-data/reports/surface-code-decoder-comparison +# +# Each shard is skipped if its output already exists (re-run safe). +# Delete a shard's JSON to regenerate it. + +set -euo pipefail + +OUTPUT_DIR="${1:---output-dir}" +if [ "$OUTPUT_DIR" = "--output-dir" ]; then + OUTPUT_DIR="${2:-/tmp/pecos_sweep}" +fi + +DATA_DIR="$OUTPUT_DIR/data" +mkdir -p "$DATA_DIR" + +GEN="uv run python examples/surface/generate_data.py" + +# Common error rates +LOW_P="0.0004 0.0008 0.001 0.0015" +MID_P="0.002 0.004 0.006 0.008 0.010 0.012 0.014" +HIGH_P="0.016 0.018 0.020" +ALL_P="$LOW_P $MID_P $HIGH_P" + +MULTI_ROUNDS="2.0 2.33 2.67 3.0" + +run_shard() { + local name="$1" + shift + local outdir="$DATA_DIR/$name" + if [ -f "$outdir/data.json" ]; then + echo "=== SKIP $name (already exists) ===" + return + fi + echo "" + echo "=== $name ===" + echo "" + $GEN "$@" --output-dir "$outdir" +} + +# --- PyMatching: all distances, all error rates, multi-round --- +run_shard pm_all_d3579 \ + --distances 3 5 7 9 \ + --error-rates $ALL_P \ + --decoders pymatching \ + --shots 5000 \ + --duration-multipliers $MULTI_ROUNDS \ + --seed 42 + +# Extra shots at very low p for PyMatching (need more to resolve rare errors) +run_shard pm_lowp_extra \ + --distances 3 5 7 9 \ + --error-rates $LOW_P \ + --decoders pymatching \ + --shots 15000 \ + --duration-multipliers $MULTI_ROUNDS \ + --seed 142 + +# --- Tesseract: d=3,5,7 multi-round, d=9 single round --- +run_shard ts_d357 \ + --distances 3 5 7 \ + --error-rates $MID_P $HIGH_P \ + --decoders tesseract \ + --shots 5000 \ + --duration-multipliers $MULTI_ROUNDS \ + --seed 200 + +run_shard ts_d9 \ + --distances 9 \ + --error-rates $MID_P \ + --decoders tesseract \ + --shots 5000 \ + --duration-multipliers 2.0 \ + --seed 300 + +# --- MWPF: d=3,5,7 single round --- +run_shard mwpf_d357 \ + --distances 3 5 7 \ + --error-rates $MID_P $HIGH_P \ + --decoders mwpf \ + --shots 5000 \ + --duration-multipliers 2.0 \ + --seed 400 + +# --- BP+OSD: d=3,5,7 single round --- +run_shard bposd_d357 \ + --distances 3 5 7 \ + --error-rates $MID_P $HIGH_P \ + --decoders bp_osd \ + --shots 5000 \ + --duration-multipliers 2.0 \ + --seed 500 + +# --- Analyze --- +echo "" +echo "=== ANALYZE ===" +echo "" +uv run python examples/surface/analyze_data.py \ + "$DATA_DIR"/*/data.json \ + -o "$OUTPUT_DIR" + +# --- Build reports --- +echo "" +echo "=== BUILD REPORTS ===" +echo "" +uv run python examples/surface/build_report.py \ + "$OUTPUT_DIR/analysis.json" \ + --html --pdf --markdown \ + -o "$OUTPUT_DIR" + +echo "" +echo "Done. Reports in $OUTPUT_DIR/" +ls -lh "$OUTPUT_DIR"/report.* diff --git a/examples/surface/surface_sweep_report.py b/examples/surface/surface_sweep_report.py new file mode 100755 index 000000000..e2a04c6d5 --- /dev/null +++ b/examples/surface/surface_sweep_report.py @@ -0,0 +1,366 @@ +#!/usr/bin/env python3 +"""Build an HTML dashboard from an existing surface sweep output directory. + +By default this only re-skins the dashboard from the SVG/JSON artifacts already +present in the directory -- useful when you want to tweak the dashboard without +rerunning the simulation. + +With ``--render-plots`` it instead re-renders every plot from the canonical +JSON results file (``*_results.json``), then writes the dashboard. This lets us +revisit data later: the JSON is the source of truth, so plots can be +regenerated with new styling, new formats, or after the SVGs were deleted. + +Examples: + # Just rebuild the dashboard from already-present SVGs + JSON: + .venv/bin/python examples/surface/surface_sweep_report.py \ + --input-dir /tmp/pecos_surface_real_sweep --open + + # Re-render plots from JSON, then rebuild the dashboard: + .venv/bin/python examples/surface/surface_sweep_report.py \ + --input-dir /tmp/pecos_surface_real_sweep --render-plots --open + + # Re-render in both SVG and PDF: + .venv/bin/python examples/surface/surface_sweep_report.py \ + --input-dir /tmp/pecos_surface_real_sweep --render-plots --formats svg pdf +""" + +from __future__ import annotations + +import argparse +import json +import re +from pathlib import Path +from typing import Any + +from native_dem_threshold_sweep import ( + DashboardPlot, + FitSummary, + _maybe_open_html_dashboard, + _write_html_dashboard, + merge_sweep_shards, + render_plot_artifacts, + write_pdf_report, +) + + +def _parse_args() -> argparse.Namespace: + parser = argparse.ArgumentParser(description=__doc__) + parser.add_argument( + "--input-dir", + type=Path, + required=True, + help="Directory containing existing surface sweep SVG and optional JSON artifacts.", + ) + parser.add_argument( + "--json-file", + "--json-files", + dest="json_files", + type=Path, + nargs="+", + default=None, + help=( + "Sweep JSON results file(s). When multiple files are given, they are " + "merged by SweepPoint key -- shot counts accumulate and fit summaries " + "are re-derived from the merged points. Omit to auto-discover a single " + "``*_results.json`` inside ``--input-dir``." + ), + ) + parser.add_argument( + "--output-html", + type=Path, + default=None, + help="Optional explicit path for the generated dashboard HTML.", + ) + parser.add_argument( + "--render-plots", + action="store_true", + help=( + "Re-render every plot from the canonical JSON results file, " + "overwriting any existing plot files in the input directory. " + "Requires that a ``*_results.json`` exists (or is given via --json-file)." + ), + ) + parser.add_argument( + "--formats", + nargs="+", + default=["svg"], + choices=["svg", "pdf"], + help="Plot file formats to write when --render-plots is set. Default: svg.", + ) + parser.add_argument( + "--report-pdf", + action="store_true", + help=( + "Also write a multi-page PDF report (cover + every plot) alongside the HTML " + "dashboard. Requires that JSON results are loadable (sweep was run with --save-json)." + ), + ) + parser.add_argument( + "--open", + action="store_true", + help="Open the generated dashboard after writing it.", + ) + return parser.parse_args() + + +def _resolve_json_paths(input_dir: Path, json_files: list[Path] | None) -> list[Path]: + """Resolve CLI JSON paths, falling back to one shard in ``input_dir`` when unset.""" + if json_files: + resolved = [path.expanduser().resolve() for path in json_files] + for path in resolved: + if not path.is_file(): + msg = f"JSON results file does not exist: {path}" + raise ValueError(msg) + return resolved + + candidates = sorted(input_dir.glob("*_results.json")) + if not candidates: + return [] + return [candidates[0]] + + +def _load_json_payload(json_path: Path | None) -> dict[str, Any] | None: + """Read a single shard's raw JSON payload (for dashboard meta display only).""" + if json_path is None: + return None + return json.loads(json_path.read_text()) + + +def _infer_output_html(input_dir: Path, json_path: Path | None, explicit_output: Path | None) -> Path: + if explicit_output is not None: + return explicit_output + if json_path is not None and json_path.name.endswith("_results.json"): + return input_dir / json_path.name.replace("_results.json", "_dashboard.html") + return input_dir / "surface_sweep_dashboard.html" + + +def _extract_backend(prefix_text: str, backends: list[str]) -> str: + for backend in sorted(backends, key=len, reverse=True): + if prefix_text.endswith(f"_{backend}"): + return backend + return prefix_text + + +def _maybe_parse_rate(rate_text: str) -> float | None: + try: + return float(rate_text.replace("p", ".", 1)) + except ValueError: + return None + + +# Matches the order in which the primary sweep script's _write_artifacts appends +# plots: combined -> duration -> basis (projected_d_rounds before per_round). +_SECTION_ORDER = {"combined": 0, "duration": 1, "basis": 2} +_BASIS_METRIC_ORDER = {"_projected_d_rounds": 0, "_per_round": 1} + + +def _plot_sort_key(plot: DashboardPlot) -> tuple: + section = _SECTION_ORDER.get(plot.section, 99) + backend = plot.backend + if plot.section == "combined": + return (section, backend) + if plot.section == "duration": + return (section, backend, plot.physical_error_rate if plot.physical_error_rate is not None else 0.0) + if plot.section == "basis": + # Read metric from filename suffix to preserve projected-before-per-round ordering. + stem = Path(plot.filename).stem + metric_rank = next( + (rank for suffix, rank in _BASIS_METRIC_ORDER.items() if stem.endswith(suffix)), + 99, + ) + return (section, backend, plot.basis or "", metric_rank) + return (section, backend) + + +def _discover_dashboard_plots(input_dir: Path, *, backends: list[str]) -> list[DashboardPlot]: + plots: list[DashboardPlot] = [] + for svg_path in sorted(input_dir.glob("*.svg")): + stem = svg_path.stem + + if stem.endswith("_per_round_overlay"): + prefix_text = stem[: -len("_per_round_overlay")] + backend = _extract_backend(prefix_text, backends) + plots.append( + DashboardPlot( + section="combined", + title=f"Per-round logical error rate vs p ({backend})", + filename=svg_path.name, + backend=backend, + ), + ) + continue + + duration_match = re.match(r"^(?P.+)_p_(?P.+)_duration_overlay$", stem) + if duration_match is not None: + prefix_text = duration_match.group("prefix") + backend = _extract_backend(prefix_text, backends) + rate = _maybe_parse_rate(duration_match.group("rate")) + rate_label = duration_match.group("rate").replace("p", ".", 1) + plots.append( + DashboardPlot( + section="duration", + title=f"Logical memory error vs duration ({backend}, p={rate_label})", + filename=svg_path.name, + backend=backend, + physical_error_rate=rate, + ), + ) + continue + + basis_match = re.match(r"^(?P.+)_(?Px|z)_(?Pper_round|projected_d_rounds)$", stem) + if basis_match is not None: + prefix_text = basis_match.group("prefix") + backend = _extract_backend(prefix_text, backends) + basis = basis_match.group("basis").upper() + metric = basis_match.group("metric") + title = ( + f"{basis}-Basis Fitted Logical Error Rate Per Round ({backend})" + if metric == "per_round" + else f"{basis}-Basis Fitted Logical Error Rate Over d Rounds ({backend})" + ) + plots.append( + DashboardPlot( + section="basis", + title=title, + filename=svg_path.name, + backend=backend, + basis=basis, + ), + ) + + plots.sort(key=_plot_sort_key) + return plots + + +def _dashboard_args(payload: dict[str, Any] | None) -> argparse.Namespace: + config = {} if payload is None else dict(payload.get("config", {})) + return argparse.Namespace( + distances=config.get("distances", []), + duration_multipliers=config.get("duration_multipliers", []), + duration_schedule_description=config.get("duration_schedule_description"), + duration_rounds_by_distance={ + int(distance): tuple(values) for distance, values in config.get("duration_rounds_by_distance", {}).items() + }, + error_rates=config.get("error_rates", []), + shots=config.get("shots", "?"), + ) + + +def _dashboard_summaries(payload: dict[str, Any] | None) -> list[FitSummary]: + if payload is None: + return [] + return [FitSummary(**row) for row in payload.get("fit_summaries", [])] + + +def _dashboard_timing_summary(payload: dict[str, Any] | None) -> dict[str, Any]: + if payload is None: + return {"overall_shots_per_second": 0.0} + return dict(payload.get("timing_summary", {"overall_shots_per_second": 0.0})) + + +def _prefix_from_json_path(json_path: Path) -> str: + """Recover the sweep ``output_prefix`` from the JSON results filename.""" + stem = json_path.name + if stem.endswith("_results.json"): + return stem[: -len("_results.json")] + return json_path.stem + + +def _merged_config_as_dashboard_args(config: dict[str, Any]) -> argparse.Namespace: + """Adapt a merged config dict to the ``argparse.Namespace`` the HTML writer expects.""" + return argparse.Namespace( + distances=config.get("distances", []), + duration_multipliers=config.get("duration_multipliers", []), + duration_schedule_description=config.get("duration_schedule_description"), + duration_rounds_by_distance={ + int(distance): tuple(values) for distance, values in config.get("duration_rounds_by_distance", {}).items() + }, + error_rates=config.get("error_rates", []), + shots=config.get("shots", "?"), + ) + + +def main() -> int: + """Build a dashboard (and optional PDF report) from one or more sweep shards.""" + args = _parse_args() + input_dir = args.input_dir.expanduser().resolve() + if not input_dir.is_dir(): + msg = f"Input directory does not exist: {input_dir}" + raise ValueError(msg) + + json_paths = _resolve_json_paths(input_dir, args.json_files) + primary_json_path = json_paths[0] if json_paths else None + output_html = _infer_output_html(input_dir, primary_json_path, args.output_html) + + # Merge (or single-shard load) when JSON is available so downstream code + # always sees the same shape of merged data regardless of shard count. + merged_points: list[Any] = [] + merged_summaries: list[FitSummary] = [] + merged_config: dict[str, Any] = {} + merged_timing: dict[str, Any] = {} + if json_paths: + merged_points, merged_summaries, merged_config, merged_timing = merge_sweep_shards(json_paths) + if len(json_paths) > 1: + print(f"Merged {len(json_paths)} shards: {[str(p) for p in json_paths]}") + + if args.render_plots or len(json_paths) > 1: + # Multi-shard merges always re-render; single-shard --render-plots + # also regenerates plot files before the dashboard assembles them. + if not json_paths: + msg = f"--render-plots requires a JSON results file in {input_dir} (or --json-file)" + raise ValueError(msg) + plots = render_plot_artifacts( + input_dir, + prefix=_prefix_from_json_path(primary_json_path), + points=merged_points, + summaries=merged_summaries, + formats=args.formats, + ) + if not plots: + msg = "Plot rendering produced no SVG entries; ensure 'svg' is in --formats." + raise ValueError(msg) + else: + backends = list(merged_config.get("executed_backends", [])) + plots = _discover_dashboard_plots(input_dir, backends=backends) + if not plots: + msg = f"No SVG plots found in {input_dir}; pass --render-plots to regenerate from JSON." + raise ValueError(msg) + + # Dashboard meta uses merged data so the HTML card counts reflect the + # combined run. When only one shard is loaded, this is identical to the + # old single-shard payload path. + raw_payload_for_meta = _load_json_payload(primary_json_path) if len(json_paths) == 1 else None + _write_html_dashboard( + output_html, + args=_merged_config_as_dashboard_args(merged_config) if json_paths else _dashboard_args(None), + summaries=(merged_summaries if json_paths else _dashboard_summaries(raw_payload_for_meta)), + timing_summary=(merged_timing if json_paths else _dashboard_timing_summary(raw_payload_for_meta)), + plots=plots, + json_filename=primary_json_path.name if primary_json_path is not None else None, + ) + print(f"Wrote HTML dashboard to {output_html}") + + if args.report_pdf: + if not json_paths: + msg = f"--report-pdf requires a JSON results file in {input_dir} (or --json-file)" + raise ValueError(msg) + report_pdf_path = output_html.with_name(output_html.name.replace("_dashboard.html", "_report.pdf")) + if report_pdf_path == output_html: + report_pdf_path = output_html.with_suffix(".pdf") + write_pdf_report( + report_pdf_path, + points=merged_points, + summaries=merged_summaries, + timing_summary=merged_timing, + config=merged_config, + ) + print(f"Wrote PDF report to {report_pdf_path}") + + if args.open: + _maybe_open_html_dashboard(output_html) + print(f"Opened HTML dashboard at {output_html}") + return 0 + + +if __name__ == "__main__": + raise SystemExit(main()) diff --git a/examples/surface/validate_dem_correlations.py b/examples/surface/validate_dem_correlations.py new file mode 100644 index 000000000..b3d008ee8 --- /dev/null +++ b/examples/surface/validate_dem_correlations.py @@ -0,0 +1,287 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Validate DEM detector correlations against simulation ground truth. + +Computes per-round detector flip frequency matrices from both simulation +and DEM sampling, then compares them element-wise. The matrix diagonal +gives marginal detection rates; off-diagonal elements give half the +joint detection probability, capturing the correlated error structure. + +Usage: + uv run python examples/surface/validate_dem_correlations.py + uv run python examples/surface/validate_dem_correlations.py -d 3 5 --shots 100000 + uv run python examples/surface/validate_dem_correlations.py --circuit-source traced_qis + uv run python examples/surface/validate_dem_correlations.py --show-matrices +""" + +from __future__ import annotations + +import argparse +import json +import sys +import time + + +def build_circuit(distance, rounds, basis, circuit_source): + from pecos.qec.surface import SurfacePatch + + patch = SurfacePatch.create(distance=distance) + + if circuit_source == "traced_qis": + from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model + + tc = _build_surface_tick_circuit_for_native_model( + patch, rounds, basis, circuit_source="traced_qis", + ) + tc.lower_clifford_rotations() + tc.assign_missing_meas_ids() + else: + from pecos.qec.surface import LogicalCircuitBuilder + + b = LogicalCircuitBuilder() + b.add_patch(patch, "Q0") + b.add_memory("Q0", rounds=rounds, basis=basis) + tc = b.to_tick_circuit() + + return tc, patch + + +def simulate_detector_events(tc, noise_kw, shots, seed): + """Run simulation and extract per-shot detector event lists.""" + from pecos_rslib_exp import depolarizing, sim_neo, stabilizer + + noise = depolarizing() + for k, v in noise_kw.items(): + if v > 0: + noise = getattr(noise, k)(v) + + det_json = json.loads(tc.get_meta("detectors")) + num_meas = int(tc.get_meta("num_measurements")) + num_dets = len(det_json) + + results = sim_neo(tc).quantum(stabilizer()).noise(noise).shots(shots).seed(seed).run() + + events = [] + for r in results: + meas = list(r) + fired = [] + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + fired.append(i) + events.append(fired) + + return events, num_dets + + +def dem_detector_events(tc, noise_kw, shots, seed): + """Sample from DEM and extract per-shot detector event lists.""" + from pecos_rslib.qec import DemSampler + + full_kw = {k: noise_kw.get(k, 0.0) for k in ["p1", "p2", "p_meas", "p_prep"]} + sampler = DemSampler.from_circuit(tc, **full_kw) + batch = sampler.generate_samples(num_shots=shots, seed=seed) + num_dets = len(json.loads(tc.get_meta("detectors"))) + + events = [] + for i in range(shots): + syn = batch.get_syndrome(i) + fired = [d for d in range(min(num_dets, len(syn))) if syn[d]] + events.append(fired) + + return events, num_dets + + +def format_matrix(matrix, width=8, precision=5): + """Format a matrix as an aligned string.""" + lines = [] + for row in matrix: + cells = [f"{v:{width}.{precision}f}" for v in row] + lines.append("[" + " ".join(cells) + "]") + return "\n".join(lines) + + +def run_validation(*, distances, bases, rounds_per_d, shots, seed, circuit_sources, + noise_configs, threshold, show_matrices, max_order): + from pecos.qec.analysis import ( + compare_flip_matrices, + compare_k_body_rates, + detector_flip_matrices_by_round, + detector_k_body_rates_by_round, + ) + + total_pass = 0 + total_fail = 0 + failures = [] + + for distance in distances: + rounds = rounds_per_d if rounds_per_d else distance + for basis in bases: + for source in circuit_sources: + tc, patch = build_circuit(distance, rounds, basis, source) + num_dets = len(json.loads(tc.get_meta("detectors"))) + n_ancilla = len(patch.x_stabilizers) + len(patch.z_stabilizers) + + src_label = f" [{source}]" if len(circuit_sources) > 1 else "" + print(f"\n{'=' * 72}") + print(f"d={distance} {basis}-basis{src_label}, {num_dets} detectors, " + f"{n_ancilla} per round, {rounds} rounds") + print(f"{'=' * 72}") + + for noise_label, noise_kw in noise_configs: + t0 = time.perf_counter() + sim_events, nd = simulate_detector_events(tc, noise_kw, shots, seed) + sim_time = time.perf_counter() - t0 + + dem_events, _ = dem_detector_events(tc, noise_kw, shots, seed) + + # --- Pairwise flip matrices --- + sim_mats = detector_flip_matrices_by_round(sim_events, nd, n_ancilla) + dem_mats = detector_flip_matrices_by_round(dem_events, nd, n_ancilla) + + all_pass = True + round_results = [] + for r_idx, (sm, dm) in enumerate(zip(sim_mats, dem_mats)): + max_err, frob_err, worst = compare_flip_matrices(sm, dm) + ok = max_err <= threshold + if not ok: + all_pass = False + round_results.append((r_idx, max_err, frob_err, worst, ok)) + + # --- Higher-order correlations --- + sim_kbody = detector_k_body_rates_by_round( + sim_events, nd, n_ancilla, max_order=max_order, + ) + dem_kbody = detector_k_body_rates_by_round( + dem_events, nd, n_ancilla, max_order=max_order, + ) + + kbody_results = [] # (round, order, max_err, rms_err, worst, ok) + for r_idx, (sr, dr) in enumerate(zip(sim_kbody, dem_kbody)): + order_stats = compare_k_body_rates(sr, dr, max_order=max_order) + for order, (me, rms, worst_ev) in order_stats.items(): + ok = me <= threshold + if not ok: + all_pass = False + kbody_results.append((r_idx, order, me, rms, worst_ev, ok)) + + # Aggregate + worst_round_err = max(rr[1] for rr in round_results) + status = "PASS" if all_pass else "FAIL" + if all_pass: + total_pass += 1 + else: + total_fail += 1 + failures.append(f"d={distance} {basis} {source} {noise_label}: " + f"{worst_round_err * 100:.0f}%") + + print(f"\n {noise_label} (sim: {sim_time:.2f}s) {status}") + + # Pairwise per-round summary + print(" Pairwise (flip matrices):") + for r_idx, max_err, frob_err, worst, ok in round_results: + flag = "" if ok else " <-- FAIL" + print(f" Round {r_idx}: max_rel={max_err * 100:5.1f}% " + f"frob_rel={frob_err * 100:5.1f}% " + f"worst={worst}{flag}") + + # Higher-order per-round summary + for order in range(1, max_order + 1): + order_entries = [(r, me, rms, w, ok) + for r, o, me, rms, w, ok in kbody_results + if o == order] + if not order_entries: + continue + worst_me = max(e[1] for e in order_entries) + avg_rms = sum(e[2] for e in order_entries) / len(order_entries) + label = {1: "1-body (marginals)", 2: "2-body (pairs)", + 3: "3-body (triples)", 4: "4-body (quads)"}.get( + order, f"{order}-body") + any_fail = any(not e[4] for e in order_entries) + flag = " <-- FAIL" if any_fail else "" + print(f" {label}: worst_max_rel={worst_me * 100:5.1f}% " + f"avg_rms_rel={avg_rms * 100:5.1f}%{flag}") + if any_fail: + for r, me, rms, w, ok in order_entries: + if not ok: + print(f" Round {r}: max_rel={me * 100:.1f}% " + f"worst={w}") + + if show_matrices and not all_pass: + for r_idx, max_err, _, _, ok in round_results: + if not ok: + print(f"\n Round {r_idx} sim:") + print(" " + format_matrix( + sim_mats[r_idx]).replace("\n", "\n ")) + print(f" Round {r_idx} dem:") + print(" " + format_matrix( + dem_mats[r_idx]).replace("\n", "\n ")) + + print(f"\n{'=' * 72}") + print(f"SUMMARY: {total_pass}/{total_pass + total_fail} passed " + f"(threshold: {threshold * 100:.0f}%)") + if failures: + print("Failures:") + for f in failures: + print(f" {f}") + print(f"{'=' * 72}") + + return total_fail == 0 + + +def main(): + parser = argparse.ArgumentParser( + description="Validate DEM detector correlations against simulation.", + ) + parser.add_argument("--distance", "-d", type=int, nargs="+", default=[2, 3], + help="Code distances (default: 2 3)") + parser.add_argument("--basis", type=str, nargs="+", default=["Z"], + choices=["Z", "X"], help="Bases (default: Z)") + parser.add_argument("--rounds", type=int, default=None, + help="Syndrome rounds (default: same as distance)") + parser.add_argument("--shots", type=int, default=100000, + help="Shots per test (default: 100000)") + parser.add_argument("--seed", type=int, default=42) + parser.add_argument("--circuit-source", choices=["abstract", "traced_qis", "both"], + default="both", help="Circuit pipeline (default: both)") + parser.add_argument("--threshold", type=float, default=0.20, + help="Max relative error threshold (default: 0.20)") + parser.add_argument("--max-order", type=int, default=3, + help="Max correlation order (default: 3)") + parser.add_argument("--show-matrices", action="store_true", + help="Print matrices for failing rounds") + + args = parser.parse_args() + + sources = (["abstract", "traced_qis"] if args.circuit_source == "both" + else [args.circuit_source]) + + noise_configs = [ + ("p_meas=0.01", {"p1": 0.0, "p2": 0.0, "p_meas": 0.01, "p_prep": 0.0}), + ("p2=0.01", {"p1": 0.0, "p2": 0.01, "p_meas": 0.0, "p_prep": 0.0}), + ("depol", {"p1": 0.001, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01}), + ("strong_depol", {"p1": 0.005, "p2": 0.05, "p_meas": 0.05, "p_prep": 0.05}), + ] + + ok = run_validation( + distances=args.distance, + bases=args.basis, + rounds_per_d=args.rounds, + shots=args.shots, + seed=args.seed, + circuit_sources=sources, + noise_configs=noise_configs, + threshold=args.threshold, + show_matrices=args.show_matrices, + max_order=args.max_order, + ) + sys.exit(0 if ok else 1) + + +if __name__ == "__main__": + main() diff --git a/examples/surface/validate_dem_generators.py b/examples/surface/validate_dem_generators.py new file mode 100644 index 000000000..d04da8486 --- /dev/null +++ b/examples/surface/validate_dem_generators.py @@ -0,0 +1,374 @@ +r"""Validate ALL DEM generators against stabilizer() ground truth. + +Systematically tests each DEM generation path across: +- Multiple distances (d=2, 3) +- Both bases (Z, X) +- Each noise component independently + combined +- All DEM generators (DemBuilder, from_circuit, exact_detection_rates, perturbative_dem) + +Uses sim_neo().quantum(stabilizer()) as ground truth for depolarizing noise. + +Example: + uv run python examples/surface/validate_dem_generators.py + uv run python examples/surface/validate_dem_generators.py --shots 50000 + uv run python examples/surface/validate_dem_generators.py -d 2 --verbose + uv run python examples/surface/validate_dem_generators.py --circuit-source both + uv run python examples/surface/validate_dem_generators.py --circuit-source traced_qis +""" + +from __future__ import annotations + +import argparse +import json +import math +import sys +import time +from pathlib import Path + +sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "python" / "quantum-pecos" / "src")) + +# Noise configurations: each component independently + combined. +# "ground_truth" specifies which simulator to use: +# "stabilizer" for depolarizing (exact, any distance) +# "statevec" for coherent noise (exact, limited to small circuits) +NOISE_CONFIGS = [ + # Depolarizing components (ground truth: stabilizer) + ("p_meas only", dict(p_meas=0.01), "stabilizer"), + ("p_prep only", dict(p_prep=0.01), "stabilizer"), + ("p1 only", dict(p1=0.01), "stabilizer"), + ("p2 only", dict(p2=0.01), "stabilizer"), + ("depol all", dict(p1=0.005, p2=0.005, p_meas=0.005, p_prep=0.005), "stabilizer"), + ("depol strong", dict(p1=0.01, p2=0.01, p_meas=0.01, p_prep=0.01), "stabilizer"), +] + +# Coherent noise configs (ground truth: statevec, small circuits only) +COHERENT_CONFIGS = [ + ("idle_rz only", dict(idle_rz=0.05), "statevec"), + ("rz+depol", dict(idle_rz=0.05, p1=0.005, p2=0.005, p_meas=0.005, p_prep=0.005), "statevec"), +] + +# Threshold for pass/fail (relative error vs stabilizer) +THRESHOLD = 0.15 # 15% — accounts for statistical noise at moderate shot counts + + +def build_circuit(distance, rounds, basis, circuit_source="abstract", fill_idle=False): + """Build surface code TickCircuit. + + circuit_source: + "abstract" — LogicalCircuitBuilder (direct gate construction) + "traced_qis" — Guppy → Selene → QIS trace → TickCircuit + fill_idle: + Insert Idle(1) gates on inactive qubits each tick. Needed for + realistic idle_rz noise (RZ applied when Idle gate is seen). + """ + from pecos.qec.surface import SurfacePatch + + patch = SurfacePatch.create(distance=distance) + + if circuit_source == "traced_qis": + from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model + tc = _build_surface_tick_circuit_for_native_model( + patch, rounds, basis, circuit_source="traced_qis", + ) + # Compilation passes for traced QIS circuits: + tc.lower_clifford_rotations() # RZ(pi/2) -> SZ, etc. + tc.assign_missing_meas_ids() # Stamp MeasId on MZ gates + else: + from pecos.qec.surface import LogicalCircuitBuilder + b = LogicalCircuitBuilder() + b.add_patch(patch, "Q0") + b.add_memory("Q0", rounds=rounds, basis=basis) + tc = b.to_tick_circuit() + + # Optional passes applied to all circuits: + if fill_idle: + # Insert Idle(1) after 2q gates (for idle_rz noise modeling) + tc.insert_idle_after_two_qubit_gates(1.0) + # Fill remaining inactive qubits with Idle gates + tc.fill_idle_gates() + + return tc + + +def ground_truth_rates(tc, noise_kw, shots, seed, det_json, num_meas, num_dets, simulator="stabilizer"): + """Ground truth: simulation with detector extraction.""" + from pecos_rslib_exp import sim_neo, stabilizer, statevec, depolarizing + + noise = depolarizing() + for k, v in noise_kw.items(): + noise = getattr(noise, k)(v) + + backend = stabilizer() if simulator == "stabilizer" else statevec() + results = sim_neo(tc).quantum(backend).noise(noise).shots(shots).seed(seed).run() + rates = [0.0] * num_dets + for r in results: + meas = list(r) + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + rates[i] += 1.0 / shots + return rates + + +def full_noise_kw(noise_kw): + """Ensure all noise params are present (default 0 for missing).""" + result = { + "p1": noise_kw.get("p1", 0.0), + "p2": noise_kw.get("p2", 0.0), + "p_meas": noise_kw.get("p_meas", 0.0), + "p_prep": noise_kw.get("p_prep", 0.0), + } + if "idle_rz" in noise_kw: + result["idle_rz"] = noise_kw["idle_rz"] + return result + + +def dem_sampler_rates(tc, noise_kw, shots, seed, num_dets): + """DemSampler.from_circuit path.""" + from pecos_rslib.qec import DemSampler + + sampler = DemSampler.from_circuit(tc, **full_noise_kw(noise_kw)) + batch = sampler.generate_samples(num_shots=shots, seed=seed) + rates = [0.0] * num_dets + for i in range(shots): + syn = batch.get_syndrome(i) + for d in range(min(num_dets, len(syn))): + if syn[d]: + rates[d] += 1.0 / shots + return rates + + +def dem_builder_rates(tc, noise_kw, shots, seed, num_dets): + """DemBuilder path (explicit, uses .to_sampler()).""" + from pecos_rslib.qec import DemBuilder, DagFaultAnalyzer + + dag = tc.to_dag_circuit() + analyzer = DagFaultAnalyzer(dag) + influence = analyzer.build_influence_map() + dem = ( + DemBuilder(influence) + .with_noise(**full_noise_kw(noise_kw)) + .with_detectors_json(tc.get_meta("detectors")) + .with_observables_json(tc.get_meta("observables")) + .with_num_measurements(int(tc.get_meta("num_measurements"))) + .build() + ) + sampler = dem.to_sampler() + batch = sampler.generate_samples(num_shots=shots, seed=seed) + rates = [0.0] * num_dets + for i in range(shots): + syn = batch.get_syndrome(i) + for d in range(min(num_dets, len(syn))): + if syn[d]: + rates[d] += 1.0 / shots + return rates + + +def heisenberg_rates(tc, noise_kw, num_dets): + """Backward Heisenberg exact detection rates.""" + from pecos_rslib_exp import exact_detection_rates + + results = exact_detection_rates(tc, **full_noise_kw(noise_kw)) + rates = [0.0] * num_dets + for det_id, prob in results: + if det_id < num_dets: + rates[det_id] = prob + return rates + + +def perturbative_rates(tc, noise_kw, num_dets): + """Forward EEG perturbative marginals.""" + from pecos_rslib_exp import perturbative_dem_events + + events = perturbative_dem_events(tc, **full_noise_kw(noise_kw)) + rates = [0.0] * num_dets + for prob, dets, _obs in events: + for d in dets: + if d < num_dets: + rates[d] += prob + return rates + + +def max_rel_error(test_rates, ref_rates, min_rate=0.003): + """Max relative error across detectors with rate > min_rate.""" + max_err = 0.0 + for t, r in zip(test_rates, ref_rates): + if r > min_rate: + max_err = max(max_err, abs(t / r - 1)) + return max_err + + +def run_validation(*, distances, bases, shots, seed, verbose, circuit_sources, fill_idle): + total_tests = 0 + total_pass = 0 + total_fail = 0 + failures = [] + + # Generators: (name, func, supports_coherent) + # from_circuit and DemBuilder only support depolarizing (no idle_rz) + generators = [ + ("from_circuit", dem_sampler_rates, False), + ("DemBuilder", dem_builder_rates, False), + ("Heisenberg", None, True), + ("Perturbative", None, True), + ] + + for distance in distances: + for basis in bases: + for circuit_source in circuit_sources: + try: + tc = build_circuit(distance, distance, basis, circuit_source, fill_idle) + except Exception as e: + print(f"\n d={distance} {basis} [{circuit_source}]: SKIP ({e})") + continue + + det_json = json.loads(tc.get_meta("detectors")) + num_meas = int(tc.get_meta("num_measurements")) + num_dets = len(det_json) + + src_label = f" [{circuit_source}]" if len(circuit_sources) > 1 else "" + print(f"\n{'='*72}") + print(f"d={distance} {basis}-basis{src_label}, {num_dets} detectors, {num_meas} measurements") + print(f"{'='*72}") + + # Combine depolarizing + coherent configs + all_configs = list(NOISE_CONFIGS) + list(COHERENT_CONFIGS) + + for noise_label, noise_kw, gt_simulator in all_configs: + is_coherent = "idle_rz" in noise_kw + + # Ground truth + t0 = time.perf_counter() + try: + ref = ground_truth_rates( + tc, noise_kw, shots, seed, det_json, num_meas, num_dets, + simulator=gt_simulator, + ) + except BaseException as e: + if verbose: + print(f"\n {noise_label}: SKIP ground truth ({type(e).__name__}: {e})") + continue + ref_time = time.perf_counter() - t0 + + if verbose: + print(f"\n {noise_label} ({gt_simulator}: {ref_time:.2f}s)") + + for gen_name, gen_func, supports_coherent in generators: + # Skip non-EEG generators for coherent noise + if is_coherent and not supports_coherent: + if verbose: + print(f" {gen_name:<14} (skipped: no coherent support)") + continue + t0 = time.perf_counter() + try: + if gen_name == "Heisenberg": + test = heisenberg_rates(tc, noise_kw, num_dets) + elif gen_name == "Perturbative": + test = perturbative_rates(tc, noise_kw, num_dets) + else: + test = gen_func(tc, noise_kw, shots, seed, num_dets) + dt = time.perf_counter() - t0 + + err = max_rel_error(test, ref) + ok = err < THRESHOLD + total_tests += 1 + if ok: + total_pass += 1 + else: + total_fail += 1 + failures.append( + f"d={distance} {basis} {noise_label} {gen_name}: {err*100:.0f}%" + ) + + status = "PASS" if ok else f"FAIL({err*100:.0f}%)" + if verbose: + print(f" {gen_name:<14} {dt*1000:>7.0f}ms {status}") + elif not ok: + print(f" {noise_label:<14} {gen_name:<14} {status}") + + except Exception as e: + total_tests += 1 + total_fail += 1 + failures.append( + f"d={distance} {basis} {noise_label} {gen_name}: ERROR {e}" + ) + if verbose: + print(f" {gen_name:<14} ERROR: {e}") + + if not verbose: + # Print summary for this config + pass + + # Final summary + print(f"\n{'='*72}") + print(f"VALIDATION SUMMARY: {total_pass}/{total_tests} passed, {total_fail} failed") + print(f"Threshold: {THRESHOLD*100:.0f}% relative error ({shots} shots)") + if failures: + print(f"\nFailures:") + for f in failures: + print(f" {f}") + else: + print("\nAll tests passed.") + print(f"{'='*72}") + + return total_fail == 0 + + +def main(): + parser = argparse.ArgumentParser( + description=__doc__, + formatter_class=argparse.RawDescriptionHelpFormatter, + ) + parser.add_argument( + "--distance", "-d", type=int, nargs="+", default=[2, 3], + help="Code distances to test (default: 2 3)" + ) + parser.add_argument( + "--basis", choices=["X", "Z"], nargs="+", default=["Z", "X"], + help="Bases to test (default: Z X)" + ) + parser.add_argument( + "--shots", type=int, default=20000, + help="Shots per test (default: 20000)" + ) + parser.add_argument( + "--seed", type=int, default=42, + ) + parser.add_argument( + "--verbose", "-v", action="store_true", + help="Show per-generator timing and results" + ) + parser.add_argument( + "--circuit-source", choices=["abstract", "traced_qis", "both"], + default="abstract", + help="Circuit construction pipeline (default: abstract)" + ) + parser.add_argument( + "--fill-idle", action="store_true", + help="Insert Idle(1) gates on inactive qubits (needed for idle_rz noise)" + ) + args = parser.parse_args() + + if args.circuit_source == "both": + sources = ["abstract", "traced_qis"] + else: + sources = [args.circuit_source] + + ok = run_validation( + distances=args.distance, + bases=args.basis, + shots=args.shots, + seed=args.seed, + verbose=args.verbose, + circuit_sources=sources, + fill_idle=args.fill_idle, + ) + sys.exit(0 if ok else 1) + + +if __name__ == "__main__": + main() diff --git a/examples/surface_code_experiments.ipynb b/examples/surface_code_experiments.ipynb index 43a38bdbd..40d1ff49f 100644 --- a/examples/surface_code_experiments.ipynb +++ b/examples/surface_code_experiments.ipynb @@ -75,7 +75,7 @@ "NUM_SHOTS = 1000\n", "DECODER_TYPES = [\"pymatching\", \"fusion_blossom\"]\n", "\n", - "# Uniform depolarizing noise: p1 = p2 = p_meas = p_init = p\n", + "# Uniform depolarizing noise: p1 = p2 = p_meas = p_prep = p\n", "ERROR_RATES = [0.001, 0.002, 0.005, 0.008, 0.01]" ] }, @@ -542,7 +542,7 @@ "\n", " for p in ERROR_RATES:\n", " error_model = DepolarizingErrorModel(p_1q=p, p_2q=p, p_meas=p, p_init=p)\n", - " noise = NoiseModel(p1=p, p2=p, p_meas=p, p_init=p)\n", + " noise = NoiseModel(p1=p, p2=p, p_meas=p, p_prep=p)\n", "\n", " # Simulate once, decode with all decoders\n", " shots = run_shots(instance, nq, NUM_SHOTS, error_model)\n", @@ -744,7 +744,7 @@ "\n", " for p in ERROR_RATES:\n", " error_model = DepolarizingErrorModel(p_1q=p, p_2q=p, p_meas=p, p_init=p)\n", - " noise = NoiseModel(p1=p, p2=p, p_meas=p, p_init=p)\n", + " noise = NoiseModel(p1=p, p2=p, p_meas=p, p_prep=p)\n", "\n", " shots = run_shots(instance, nq, NUM_SHOTS, error_model)\n", "\n", diff --git a/examples/surface_code_noisy_decoding.ipynb b/examples/surface_code_noisy_decoding.ipynb index cabb4a10c..96404c39c 100644 --- a/examples/surface_code_noisy_decoding.ipynb +++ b/examples/surface_code_noisy_decoding.ipynb @@ -101,7 +101,7 @@ } }, "outputs": [], - "source": "from typing import Any\n\n\ndef get_logical_qubits(distance: int, basis: str) -> tuple:\n \"\"\"Get qubits in the logical operator.\"\"\"\n patch = SurfacePatch.create(distance=distance)\n if basis == \"Z\":\n return patch.geometry.logical_z.data_qubits\n return patch.geometry.logical_x.data_qubits\n\n\ndef run_memory_experiment(\n distance: int,\n num_rounds: int,\n num_shots: int,\n basis: str,\n error_model: Any,\n *,\n decode: bool = False,\n decoder_type: str = \"pymatching\",\n) -> dict:\n \"\"\"Run memory experiment and compute logical error rate.\n\n For Z-basis: prepare |0_L>, measure in Z basis, check logical Z parity.\n For X-basis: prepare |+_L>, measure in X basis, check logical X parity.\n\n Args:\n distance: Code distance\n num_rounds: Number of syndrome extraction rounds\n num_shots: Number of shots to run\n basis: 'Z' or 'X' basis\n error_model: Selene error model (IdealErrorModel or DepolarizingErrorModel)\n decode: If True, use decoding to correct errors\n decoder_type: Decoder backend ('pymatching', 'fusion_blossom', 'bp_osd', 'bp_lsd', 'union_find', 'tesseract')\n\n Returns:\n Dictionary with experiment results\n \"\"\"\n patch = SurfacePatch.create(distance=distance)\n logical_qubits = get_logical_qubits(distance, basis)\n\n # Create decoder if needed\n decoder = None\n if decode:\n # Extract noise parameters from error model\n noise = NoiseModel(\n p1=getattr(error_model, \"p_1q\", 0.01),\n p2=getattr(error_model, \"p_2q\", 0.01),\n p_meas=getattr(error_model, \"p_meas\", 0.01),\n p_init=getattr(error_model, \"p_init\", 0.01),\n )\n decoder = SurfaceDecoder(patch, num_rounds=num_rounds, noise=noise, decoder_type=decoder_type)\n\n # Build circuit\n num_qubits = get_num_qubits(distance)\n prog = make_surface_code(distance=distance, num_rounds=num_rounds, basis=basis)\n hugr_bytes = compile_guppy_to_hugr(prog)\n instance = build(hugr_bytes, name=f\"surface_d{distance}\")\n\n # Run\n num_logical_errors = 0\n num_raw_errors = 0\n\n for shot_results in instance.run_shots(\n simulator=Stim(),\n n_qubits=num_qubits,\n n_shots=num_shots,\n error_model=error_model,\n runtime=SimpleRuntime(),\n n_processes=1,\n ):\n # Collect all syndromes properly (multiple entries per key)\n synx_list = []\n synz_list = []\n final = None\n\n for name, values in shot_results:\n vals = list(values)\n if name == \"synx\":\n synx_list.append(np.array(vals, dtype=np.uint8))\n elif name == \"synz\":\n synz_list.append(np.array(vals, dtype=np.uint8))\n elif name == \"final\":\n final = vals\n\n if final is None:\n continue\n\n # Raw parity check (no decoding)\n raw_parity = sum(final[q] for q in logical_qubits) % 2\n if raw_parity != 0:\n num_raw_errors += 1\n\n if decode and decoder is not None:\n final_arr = np.array(final, dtype=np.uint8)\n\n # Decode based on basis\n if basis == \"Z\":\n is_error, _ = decoder.decode_memory_z(synx_list, synz_list, final_arr)\n else:\n is_error, _ = decoder.decode_memory_x(synx_list, synz_list, final_arr)\n\n if is_error:\n num_logical_errors += 1\n else:\n # No decoding - use raw parity\n if raw_parity != 0:\n num_logical_errors += 1\n\n return {\n \"distance\": distance,\n \"num_shots\": num_shots,\n \"num_logical_errors\": num_logical_errors,\n \"num_raw_errors\": num_raw_errors,\n \"logical_error_rate\": num_logical_errors / num_shots,\n \"raw_error_rate\": num_raw_errors / num_shots,\n \"decoded\": decode,\n \"decoder_type\": decoder_type if decode else None,\n }" + "source": "from typing import Any\n\n\ndef get_logical_qubits(distance: int, basis: str) -> tuple:\n \"\"\"Get qubits in the logical operator.\"\"\"\n patch = SurfacePatch.create(distance=distance)\n if basis == \"Z\":\n return patch.geometry.logical_z.data_qubits\n return patch.geometry.logical_x.data_qubits\n\n\ndef run_memory_experiment(\n distance: int,\n num_rounds: int,\n num_shots: int,\n basis: str,\n error_model: Any,\n *,\n decode: bool = False,\n decoder_type: str = \"pymatching\",\n) -> dict:\n \"\"\"Run memory experiment and compute logical error rate.\n\n For Z-basis: prepare |0_L>, measure in Z basis, check logical Z parity.\n For X-basis: prepare |+_L>, measure in X basis, check logical X parity.\n\n Args:\n distance: Code distance\n num_rounds: Number of syndrome extraction rounds\n num_shots: Number of shots to run\n basis: 'Z' or 'X' basis\n error_model: Selene error model (IdealErrorModel or DepolarizingErrorModel)\n decode: If True, use decoding to correct errors\n decoder_type: Decoder backend ('pymatching', 'fusion_blossom', 'bp_osd', 'bp_lsd', 'union_find', 'tesseract')\n\n Returns:\n Dictionary with experiment results\n \"\"\"\n patch = SurfacePatch.create(distance=distance)\n logical_qubits = get_logical_qubits(distance, basis)\n\n # Create decoder if needed\n decoder = None\n if decode:\n # Extract noise parameters from error model\n noise = NoiseModel(\n p1=getattr(error_model, \"p_1q\", 0.01),\n p2=getattr(error_model, \"p_2q\", 0.01),\n p_meas=getattr(error_model, \"p_meas\", 0.01),\n p_prep=getattr(error_model, \"p_init\", 0.01),\n )\n decoder = SurfaceDecoder(patch, num_rounds=num_rounds, noise=noise, decoder_type=decoder_type)\n\n # Build circuit\n num_qubits = get_num_qubits(distance)\n prog = make_surface_code(distance=distance, num_rounds=num_rounds, basis=basis)\n hugr_bytes = compile_guppy_to_hugr(prog)\n instance = build(hugr_bytes, name=f\"surface_d{distance}\")\n\n # Run\n num_logical_errors = 0\n num_raw_errors = 0\n\n for shot_results in instance.run_shots(\n simulator=Stim(),\n n_qubits=num_qubits,\n n_shots=num_shots,\n error_model=error_model,\n runtime=SimpleRuntime(),\n n_processes=1,\n ):\n # Collect all syndromes properly (multiple entries per key)\n synx_list = []\n synz_list = []\n final = None\n\n for name, values in shot_results:\n vals = list(values)\n if name == \"synx\":\n synx_list.append(np.array(vals, dtype=np.uint8))\n elif name == \"synz\":\n synz_list.append(np.array(vals, dtype=np.uint8))\n elif name == \"final\":\n final = vals\n\n if final is None:\n continue\n\n # Raw parity check (no decoding)\n raw_parity = sum(final[q] for q in logical_qubits) % 2\n if raw_parity != 0:\n num_raw_errors += 1\n\n if decode and decoder is not None:\n final_arr = np.array(final, dtype=np.uint8)\n\n # Decode based on basis\n if basis == \"Z\":\n is_error, _ = decoder.decode_memory_z(synx_list, synz_list, final_arr)\n else:\n is_error, _ = decoder.decode_memory_x(synx_list, synz_list, final_arr)\n\n if is_error:\n num_logical_errors += 1\n else:\n # No decoding - use raw parity\n if raw_parity != 0:\n num_logical_errors += 1\n\n return {\n \"distance\": distance,\n \"num_shots\": num_shots,\n \"num_logical_errors\": num_logical_errors,\n \"num_raw_errors\": num_raw_errors,\n \"logical_error_rate\": num_logical_errors / num_shots,\n \"raw_error_rate\": num_raw_errors / num_shots,\n \"decoded\": decode,\n \"decoder_type\": decoder_type if decode else None,\n }" }, { "cell_type": "markdown", @@ -1094,7 +1094,7 @@ "\n", "# Create a decoder configuration\n", "patch = SurfacePatch.create(distance=3)\n", - "noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.01, p_init=0.001)\n", + "noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.01, p_prep=0.001)\n", "\n", "# Generate DEM using PECOS native pipeline\n", "tc = generate_tick_circuit_from_patch(patch, num_rounds=3, basis=\"Z\")\n", @@ -1110,12 +1110,12 @@ "\n", "# Build DEM\n", "builder = DemBuilder(influence_map)\n", - "builder.with_noise(noise.p1, noise.p2, noise.p_meas, noise.p_init)\n", + "builder.with_noise(noise.p1, noise.p2, noise.p_meas, noise.p_prep)\n", "builder.with_num_measurements(num_measurements)\n", "builder.with_measurement_order(measurement_order)\n", "builder.with_detectors_json(detectors_json)\n", "if observables_json:\n", - " builder.with_observables_json(observables_json)\n", + " builder.with_tracked_ops_json(observables_json)\n", "\n", "pecos_dem = builder.build()\n", "\n", @@ -1535,7 +1535,7 @@ " p1=0.001, # Single-qubit gate error\n", " p2=0.01, # Two-qubit gate error\n", " p_meas=0.01, # Measurement error\n", - " p_init=0.001, # Initialization error\n", + " p_prep=0.001, # Initialization error\n", ")\n", "\n", "# Parse and generate DEM\n", @@ -1596,7 +1596,7 @@ "\n", "# Construct DEM\n", "builder = DemBuilder(influence_map)\n", - "builder.with_noise(p1, p2, p_meas, p_init)\n", + "builder.with_noise(p1, p2, p_meas, p_prep)\n", "builder.with_detectors_json(tc.get_meta(\"detectors\"))\n", "dem = builder.build()\n", "\n", @@ -1650,7 +1650,7 @@ " p1=0.001, # Single-qubit gate error rate\n", " p2=0.01, # Two-qubit gate error rate\n", " p_meas=0.01, # Measurement error rate\n", - " p_init=0.001, # Initialization error rate\n", + " p_prep=0.001, # Initialization error rate\n", ")\n", "```" ] diff --git a/examples/surface_code_selene_demo.ipynb b/examples/surface_code_selene_demo.ipynb index d9b849f24..bc8742626 100644 --- a/examples/surface_code_selene_demo.ipynb +++ b/examples/surface_code_selene_demo.ipynb @@ -84,7 +84,7 @@ "P1 = 4e-5 # Single-qubit gate error\n", "P2 = 1e-3 # Two-qubit gate error\n", "P_MEAS = 4e-4 # Measurement error\n", - "P_INIT = 4e-4 # Initialization error" + "P_PREP = 4e-4 # Initialization error" ] }, { @@ -214,7 +214,7 @@ "print()\n", "\n", "# 2. Stim circuit (for Stim simulation and DEM generation)\n", - "stim_circuit = generate_stim_from_patch(patch, NUM_ROUNDS, BASIS, p1=P1, p2=P2, p_meas=P_MEAS, p_init=P_INIT)\n", + "stim_circuit = generate_stim_from_patch(patch, NUM_ROUNDS, BASIS, p1=P1, p2=P2, p_meas=P_MEAS, p_prep=P_PREP)\n", "stim_lines = stim_circuit.strip().split(\"\\n\")\n", "print(f\"2. Stim circuit: {len(stim_lines)} lines\")\n", "print(f\" Preview: {stim_lines[0]}\")\n", @@ -668,7 +668,7 @@ "PECOS provides native DEM generation that works directly with TickCircuit,\n", "without requiring Stim as an intermediate step. The workflow is:\n", "\n", - "1. `SurfacePatch` -> `TickCircuit` (with detector/observable metadata)\n", + "1. `SurfacePatch` -> `TickCircuit` (with detector/tracked-op metadata)\n", "2. `TickCircuit` -> `DagCircuit` -> `DagFaultAnalyzer` -> `DemBuilder`\n", "3. `DemBuilder` -> DEM string (Stim-compatible format)\n", "\n", @@ -709,7 +709,7 @@ " p1: float,\n", " p2: float,\n", " p_meas: float,\n", - " p_init: float,\n", + " p_prep: float,\n", ") -> \"DetectorErrorModel\":\n", " \"\"\"Generate DEM using PECOS native fault propagation.\n", "\n", @@ -731,12 +731,12 @@ "\n", " # Build DEM using Rust DemBuilder\n", " builder = DemBuilder(influence_map)\n", - " builder.with_noise(p1, p2, p_meas, p_init)\n", + " builder.with_noise(p1, p2, p_meas, p_prep)\n", " builder.with_num_measurements(num_measurements)\n", " builder.with_measurement_order(measurement_order)\n", " builder.with_detectors_json(detectors_json)\n", " if observables_json:\n", - " builder.with_observables_json(observables_json)\n", + " builder.with_tracked_ops_json(observables_json)\n", "\n", " return builder.build()" ] @@ -773,7 +773,7 @@ "# Method 1: Via Stim (for reference)\n", "noisy_stim = generate_stim_from_patch(\n", " patch, num_rounds=NUM_ROUNDS, basis=BASIS,\n", - " p1=P1, p2=P2, p_meas=P_MEAS, p_init=P_INIT,\n", + " p1=P1, p2=P2, p_meas=P_MEAS, p_prep=P_PREP,\n", ")\n", "circuit = stim.Circuit(noisy_stim)\n", "stim_dem = circuit.detector_error_model(decompose_errors=True)\n", @@ -788,7 +788,7 @@ "# Method 2: Native PECOS\n", "pecos_dem = generate_pecos_dem(\n", " patch, num_rounds=NUM_ROUNDS, basis=BASIS,\n", - " p1=P1, p2=P2, p_meas=P_MEAS, p_init=P_INIT,\n", + " p1=P1, p2=P2, p_meas=P_MEAS, p_prep=P_PREP,\n", ")\n", "pecos_raw_str = pecos_dem.to_string()\n", "pecos_decomp_str = pecos_dem.to_string_decomposed()\n", @@ -935,7 +935,7 @@ " Stim DEM raw: 2063 lines\n", " Stim DEM decomposed: 2384 lines\n", "\n", - "Noise parameters: p1=4e-05, p2=0.001, p_meas=0.0004, p_init=0.0004\n", + "Noise parameters: p1=4e-05, p2=0.001, p_meas=0.0004, p_prep=0.0004\n", "Syndrome rounds: 3\n" ] } @@ -969,13 +969,13 @@ " # Generate Stim circuit (with noise)\n", " stim_full = generate_stim_from_patch(\n", " patch, num_rounds=NUM_ROUNDS, basis=basis,\n", - " p1=P1, p2=P2, p_meas=P_MEAS, p_init=P_INIT,\n", + " p1=P1, p2=P2, p_meas=P_MEAS, p_prep=P_PREP,\n", " )\n", "\n", " # Generate PECOS DEMs (raw and decomposed)\n", " pecos_dem_obj = generate_pecos_dem(\n", " patch, num_rounds=NUM_ROUNDS, basis=basis,\n", - " p1=P1, p2=P2, p_meas=P_MEAS, p_init=P_INIT,\n", + " p1=P1, p2=P2, p_meas=P_MEAS, p_prep=P_PREP,\n", " )\n", " pecos_dem_raw = pecos_dem_obj.to_string()\n", " pecos_dem_decomposed = pecos_dem_obj.to_string_decomposed()\n", @@ -1005,7 +1005,7 @@ " print(f\" Stim DEM decomposed: {len(stim_dem_decomposed.splitlines())} lines\")\n", " print()\n", "\n", - "print(f\"Noise parameters: p1={P1}, p2={P2}, p_meas={P_MEAS}, p_init={P_INIT}\")\n", + "print(f\"Noise parameters: p1={P1}, p2={P2}, p_meas={P_MEAS}, p_prep={P_PREP}\")\n", "print(f\"Syndrome rounds: {NUM_ROUNDS}\")" ] }, @@ -4527,13 +4527,13 @@ " p = SurfacePatch.create(distance=d)\n", "\n", " # Stim DEM (decomposed)\n", - " stim_str = generate_stim_from_patch(p, NUM_ROUNDS, BASIS, p1=P1, p2=P2, p_meas=P_MEAS, p_init=P_INIT)\n", + " stim_str = generate_stim_from_patch(p, NUM_ROUNDS, BASIS, p1=P1, p2=P2, p_meas=P_MEAS, p_prep=P_PREP)\n", " c = stim.Circuit(stim_str)\n", " stim_dem = c.detector_error_model(decompose_errors=True)\n", " stim_errors = count_dem_errors(str(stim_dem))\n", "\n", " # PECOS DEM (decomposed)\n", - " pecos_dem = generate_pecos_dem(p, NUM_ROUNDS, BASIS, p1=P1, p2=P2, p_meas=P_MEAS, p_init=P_INIT)\n", + " pecos_dem = generate_pecos_dem(p, NUM_ROUNDS, BASIS, p1=P1, p2=P2, p_meas=P_MEAS, p_prep=P_PREP)\n", " pecos_decomposed = pecos_dem.to_string_decomposed()\n", " pecos_errors = count_dem_errors(pecos_decomposed)\n", " pecos_prob = sum_dem_probability(pecos_decomposed)\n", @@ -4571,7 +4571,7 @@ "tc = generate_tick_circuit_from_patch(patch, num_rounds=NUM_ROUNDS, basis=BASIS)\n", "\n", "# One-liner DEM generation from TickCircuit (outputs decomposed format by default)\n", - "dem_str = generate_dem_from_tick_circuit(tc, p1=P1, p2=P2, p_meas=P_MEAS, p_init=P_INIT)\n", + "dem_str = generate_dem_from_tick_circuit(tc, p1=P1, p2=P2, p_meas=P_MEAS, p_prep=P_PREP)\n", "\n", "print(\"=== generate_dem_from_tick_circuit output (first 10 error lines) ===\")\n", "error_lines = [err_line for err_line in dem_str.split(\"\\n\") if err_line.startswith(\"error(\")]\n", diff --git a/examples/surface_code_slr_exploration.ipynb b/examples/surface_code_slr_exploration.ipynb index c2acf6bc6..9f286c86c 100644 --- a/examples/surface_code_slr_exploration.ipynb +++ b/examples/surface_code_slr_exploration.ipynb @@ -630,7 +630,7 @@ "\n", "4. **Key gaps for parity with circuit builder:**\n", " - No TickCircuit generator\n", - " - No detector/observable annotation support\n", + " - No detector/tracked-op annotation support\n", " - No semantic phase metadata\n", " - No gate-level metadata (labels, stabilizer info)\n", " - No CNOT scheduling in SLR's surface library\n", diff --git a/examples/surface_code_threshold.ipynb b/examples/surface_code_threshold.ipynb index f0ae082f3..ab5977207 100644 --- a/examples/surface_code_threshold.ipynb +++ b/examples/surface_code_threshold.ipynb @@ -18,7 +18,7 @@ "\n", "**Setup:**\n", "- Distances 9, 11, 13, 15 (avoiding finite-size effects)\n", - "- Uniform depolarizing noise (p1 = p2 = p_meas = p_init = p)\n", + "- Uniform depolarizing noise (p1 = p2 = p_meas = p_prep = p)\n", "- 2*d syndrome rounds per distance\n", "- Selene simulation with Stim backend\n", "\n", @@ -164,12 +164,12 @@ " measurement_order = _extract_measurement_order(tc)\n", "\n", " builder = DemBuilder(influence_map)\n", - " builder.with_noise(noise.p1, noise.p2, noise.p_meas, noise.p_init)\n", + " builder.with_noise(noise.p1, noise.p2, noise.p_meas, noise.p_prep)\n", " builder.with_num_measurements(num_measurements)\n", " builder.with_measurement_order(measurement_order)\n", " builder.with_detectors_json(detectors_json)\n", " if observables_json:\n", - " builder.with_observables_json(observables_json)\n", + " builder.with_tracked_ops_json(observables_json)\n", "\n", " dem = builder.build()\n", " return dem.to_string(), dem.to_string_decomposed()\n", @@ -438,7 +438,7 @@ "\n", " for p in ERROR_RATES:\n", " error_model = DepolarizingErrorModel(p_1q=p, p_2q=p, p_meas=p, p_init=p)\n", - " noise = NoiseModel(p1=p, p2=p, p_meas=p, p_init=p)\n", + " noise = NoiseModel(p1=p, p2=p, p_meas=p, p_prep=p)\n", "\n", " t0 = time.time()\n", " shots = run_shots(instance, nq, NUM_SHOTS, error_model)\n", @@ -487,7 +487,7 @@ "\n", " for p in ERROR_RATES:\n", " error_model = DepolarizingErrorModel(p_1q=p, p_2q=p, p_meas=p, p_init=p)\n", - " noise = NoiseModel(p1=p, p2=p, p_meas=p, p_init=p)\n", + " noise = NoiseModel(p1=p, p2=p, p_meas=p, p_prep=p)\n", "\n", " t0 = time.time()\n", " shots = run_shots(instance, nq, NUM_SHOTS, error_model)\n", @@ -646,7 +646,7 @@ "by comparing 5 decoder/DEM variants, all using PyMatching MWPM.\n", "\n", "**Setup:**\n", - "- Uniform depolarizing noise: p1 = p2 = p_meas = p_init = p\n", + "- Uniform depolarizing noise: p1 = p2 = p_meas = p_prep = p\n", "- 2*d syndrome rounds per distance\n", "- Distances 9-15 to minimize finite-size effects\n", "\n", diff --git a/examples/surface_code_thresholds.ipynb b/examples/surface_code_thresholds.ipynb index cdde5afb8..2f5050c2e 100644 --- a/examples/surface_code_thresholds.ipynb +++ b/examples/surface_code_thresholds.ipynb @@ -339,7 +339,7 @@ "def generate_code_capacity_dem(patch: SurfacePatch, num_rounds: int, p: float) -> str:\n", " \"\"\"Generate a code-capacity DEM (data errors only, perfect measurements).\"\"\"\n", " # Use phenomenological DEM with p_meas=0\n", - " noise = NoiseModel(p1=0, p2=p, p_meas=0, p_init=0)\n", + " noise = NoiseModel(p1=0, p2=p, p_meas=0, p_prep=0)\n", " return generate_surface_code_dem(patch, num_rounds=1, noise=noise, stab_type=\"Z\")\n", "\n", "# Test DEM generation\n", @@ -424,7 +424,7 @@ "source": [ "def generate_phenomenological_dem(patch: SurfacePatch, num_rounds: int, p: float) -> str:\n", " \"\"\"Generate a phenomenological DEM (data + measurement errors).\"\"\"\n", - " noise = NoiseModel(p1=0, p2=p, p_meas=p, p_init=0)\n", + " noise = NoiseModel(p1=0, p2=p, p_meas=p, p_prep=0)\n", " return generate_surface_code_dem(patch, num_rounds=num_rounds, noise=noise, stab_type=\"Z\")\n", "\n", "# Test DEM generation\n", @@ -510,7 +510,7 @@ "def generate_circuit_level_dem(patch: SurfacePatch, num_rounds: int, p: float) -> str:\n", " \"\"\"Generate a circuit-level DEM using PECOS native fault propagation.\"\"\"\n", " # Use same error rate for all noise sources (standard depolarizing)\n", - " noise = NoiseModel(p1=p, p2=p, p_meas=p, p_init=p)\n", + " noise = NoiseModel(p1=p, p2=p, p_meas=p, p_prep=p)\n", " return generate_circuit_level_dem_from_builder(patch, num_rounds=num_rounds, noise=noise, basis=\"Z\")\n", "\n", "# Test DEM generation\n", diff --git a/exp/pecos-eeg/Cargo.toml b/exp/pecos-eeg/Cargo.toml new file mode 100644 index 000000000..ceef7c350 --- /dev/null +++ b/exp/pecos-eeg/Cargo.toml @@ -0,0 +1,29 @@ +[package] +name = "pecos-eeg" +version.workspace = true +edition.workspace = true +authors.workspace = true +homepage.workspace = true +repository.workspace = true +license.workspace = true +keywords.workspace = true +categories.workspace = true +description = "EEG-based coherent noise analysis and DEM generation" +publish = false + +[lib] +crate-type = ["rlib"] + +[dependencies] +pecos-core.workspace = true +pecos-qec.workspace = true +pecos-quantum.workspace = true +pecos-random.workspace = true +pecos-simulators.workspace = true +serde_json.workspace = true +rayon.workspace = true +smallvec.workspace = true +thiserror.workspace = true + +[lints] +workspace = true diff --git a/exp/pecos-eeg/examples/profile_heisenberg.rs b/exp/pecos-eeg/examples/profile_heisenberg.rs new file mode 100644 index 000000000..3f7a6f786 --- /dev/null +++ b/exp/pecos-eeg/examples/profile_heisenberg.rs @@ -0,0 +1,82 @@ +//! Profile the Heisenberg DEM build. +//! Usage: cargo run -p pecos-eeg --example profile_heisenberg --profile profiling +//! Perf: perf record -g -F 4999 -- target/profiling/examples/profile_heisenberg + +use pecos_core::gate_type::GateType; +use pecos_core::pauli::pauli_bitmask::BitmaskStorage; +use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; +use pecos_eeg::Bm; +use std::time::Instant; + +fn gate(gt: GateType, qubits: &[usize]) -> Gate { + Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), + } +} + +/// Build a single weight-4 X-check plaquette with 4 data + 1 ancilla, N rounds. +/// This is the hotspot structure in surface codes. +fn build_weight4_circuit(num_rounds: usize) -> Vec { + // Data: 0,1,2,3. Ancilla: 4. + let mut gates = Vec::new(); + for q in 0..5 { gates.push(gate(GateType::PZ, &[q])); } + for round in 0..num_rounds { + gates.push(gate(GateType::H, &[4])); + gates.push(gate(GateType::CX, &[4, 0])); + gates.push(gate(GateType::CX, &[4, 1])); + gates.push(gate(GateType::CX, &[4, 2])); + gates.push(gate(GateType::CX, &[4, 3])); + gates.push(gate(GateType::H, &[4])); + gates.push(gate(GateType::MZ, &[4])); + if round < num_rounds - 1 { + gates.push(gate(GateType::PZ, &[4])); + } + } + for q in 0..4 { gates.push(gate(GateType::MZ, &[q])); } + gates +} + +fn main() { + let num_rounds = 8; + let gates = build_weight4_circuit(num_rounds); + let noise = pecos_eeg::noise::UniformNoise::coherent_only(0.05); + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let na = 1; // one ancilla + + let mut detectors = Vec::new(); + for round in 0..(num_rounds - 1) { + let m1 = round * na; + let m2 = (round + 1) * na; + let mut det = Bm::default(); + det.z_bits.set_bit(expanded.measurement_qubit[m1]); + det.z_bits.set_bit(expanded.measurement_qubit[m2]); + detectors.push(det); + } + + let init_gates: Vec = (0..5) + .map(|q| pecos_eeg::expand::make_gate(GateType::PZ, &[q])) + .collect(); + let stab = pecos_eeg::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); + + eprintln!("Weight-4 X-check, {num_rounds} rounds, {} expanded qubits, {} detectors", + expanded.num_qubits, detectors.len()); + + // Run 20 iterations to get enough samples for perf + let iters = 20; + let t = Instant::now(); + for _ in 0..iters { + for det in &detectors { + let _p = pecos_eeg::heisenberg::heisenberg_detection_probability( + &expanded.gates, det, &noise, &stab, 0.0, + ); + } + } + let total = t.elapsed(); + let per_det = total.as_secs_f64() * 1000.0 / (detectors.len() * iters) as f64; + eprintln!("{iters} iterations x {} dets = {} calls in {:.2}s ({:.2}ms/det)", + detectors.len(), detectors.len() * iters, total.as_secs_f64(), per_det); +} diff --git a/exp/pecos-eeg/src/builder.rs b/exp/pecos-eeg/src/builder.rs new file mode 100644 index 000000000..c9cf24957 --- /dev/null +++ b/exp/pecos-eeg/src/builder.rs @@ -0,0 +1,363 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! EEG DEM builder: TickCircuit + noise → DEM events. + +use crate::Bm; +use crate::circuit::{self, NoiseModel}; +use crate::dem_mapping::{self, DemEntry, Detector, Observable}; +use crate::expand; +use crate::stabilizer::StabilizerGroup; +use pecos_core::pauli::pauli_bitmask::BitmaskStorage; +use pecos_quantum::{AnnotationKind, TickCircuit}; + +pub struct EegDemBuilder<'a> { + tc: &'a TickCircuit, + noise: NoiseModel, + config: dem_mapping::EegConfig, +} + +impl<'a> EegDemBuilder<'a> { + #[must_use] + pub fn from_tick_circuit(tc: &'a TickCircuit) -> Self { + Self { + tc, + noise: NoiseModel::coherent_only(0.0), + config: dem_mapping::EegConfig::default(), + } + } + + #[must_use] + pub fn noise(mut self, noise: NoiseModel) -> Self { + self.noise = noise; + self + } + + /// Set the full EEG configuration. + #[must_use] + pub fn config(mut self, config: dem_mapping::EegConfig) -> Self { + self.config = config; + self + } + + /// Use the exact sin^2(h) formula instead of leading-order h^2. + #[must_use] + pub fn exact_h_formula(mut self) -> Self { + self.config.h_formula = dem_mapping::HFormula::SinSquared; + self + } + + /// Use second-order BCH (includes [H,H] commutator corrections). + #[must_use] + pub fn bch_order_2(mut self) -> Self { + self.config.bch_order = dem_mapping::BchOrder::Second; + self + } + + #[must_use] + pub fn build(&self) -> Vec { + let gates: Vec = self.tc.iter_gates().cloned().collect(); + let expanded = expand::expand_circuit(&gates); + let result = circuit::analyze_expanded(&expanded.gates, &self.noise); + let (detectors, observables) = build_detectors( + self.tc, &expanded, + ); + + // Compute stabilizer group from the EXPANDED circuit (pre-readout). + // This includes auxiliary qubits, so beta function checks happen + // directly in the expanded frame without lossy frame mapping. + // Exclude the final deferred MZ(aux) gates at the end. + let expanded_pre_readout = exclude_final_mz(&expanded.gates); + let stab_group = StabilizerGroup::from_circuit(&expanded_pre_readout, expanded.num_qubits); + + dem_mapping::build_dem_configured( + &result.generators, &detectors, &observables, + Some(&stab_group), &self.config, + ) + } + + #[must_use] + pub fn build_dem_string(&self) -> String { + dem_mapping::format_dem(&self.build()) + } + + #[must_use] + pub fn summary(&self) -> EegSummary { + let gates: Vec = self.tc.iter_gates().cloned().collect(); + let expanded = expand::expand_circuit(&gates); + let result = circuit::analyze_expanded(&expanded.gates, &self.noise); + let (detectors, observables) = build_detectors(self.tc, &expanded); + + let expanded_pre = exclude_final_mz(&expanded.gates); + let stab_group = StabilizerGroup::from_circuit(&expanded_pre, expanded.num_qubits); + let entries = dem_mapping::build_dem_configured( + &result.generators, &detectors, &observables, + Some(&stab_group), &self.config, + ); + + let h_count = result.generators.iter() + .filter(|g| g.eeg_type == crate::eeg::EegType::H).count(); + let s_count = result.generators.iter() + .filter(|g| g.eeg_type == crate::eeg::EegType::S).count(); + + EegSummary { + num_original_gates: gates.len(), + num_expanded_gates: expanded.gates.len(), + num_expanded_qubits: expanded.num_qubits, + num_h_generators: h_count, + num_s_generators: s_count, + num_detectors: detectors.len(), + num_observables: observables.len(), + num_dem_events: entries.len(), + generator_fidelity: result.generator_fidelity(), + } + } +} + +#[derive(Clone, Debug)] +pub struct EegSummary { + pub num_original_gates: usize, + pub num_expanded_gates: usize, + pub num_expanded_qubits: usize, + pub num_h_generators: usize, + pub num_s_generators: usize, + pub num_detectors: usize, + pub num_observables: usize, + pub num_dem_events: usize, + /// Generator fidelity: ε_gen = Σ h_P² + Σ |s_P|. DEM error scales as ε_gen^{1.5}. + pub generator_fidelity: f64, +} + +/// Strip all trailing MZ gates from the expanded circuit. +/// +/// The expanded circuit ends with deferred MZ(aux) gates. Stripping them +/// gives the pre-readout expanded state for stabilizer group computation. +fn exclude_final_mz(gates: &[pecos_core::Gate]) -> Vec { + let last_non_mz = gates.iter().rposition(|g| { + g.gate_type != pecos_core::gate_type::GateType::MZ + }); + match last_non_mz { + Some(idx) => gates[..=idx].to_vec(), + None => Vec::new(), + } +} + +/// Build detectors for the expanded circuit from TickCircuit annotations. +/// +/// Each detector is defined by measurement records (negative indices from +/// the end of the measurement sequence). In the expanded circuit, each +/// measurement record k maps to a Z-measurement on auxiliary qubit +/// `expanded.measurement_qubit[k]`. +/// +/// The detector stabilizer in the expanded circuit is: +/// Z_{aux_r1} * Z_{aux_r2} * ... +/// where aux_ri = expanded.measurement_qubit[abs_index(ri)] +fn build_detectors( + tc: &TickCircuit, + expanded: &expand::ExpandedCircuit, +) -> (Vec, Vec) { + let mut detectors = Vec::new(); + let mut observables = Vec::new(); + let num_meas = expanded.measurement_qubit.len(); + + for annotation in tc.annotations() { + match &annotation.kind { + AnnotationKind::Detector { measurement_nodes, .. } => { + // measurement_nodes are gate indices in the ORIGINAL circuit. + // We need to map these to measurement record indices, then + // to auxiliary qubits in the expanded circuit. + // + // The gate indices correspond to MZ gates. Each MZ gate can + // measure multiple qubits. We need to find which measurement + // record each gate index maps to. + // + // Strategy: the k-th measurement record corresponds to the + // k-th qubit measured across all MZ gates in order. Each + // measurement_node is a gate index — we find which measurement + // records that gate produced. + let bitmask = measurement_nodes_to_aux_bitmask( + measurement_nodes, tc, expanded, num_meas, + ); + detectors.push(Detector { id: detectors.len(), stabilizer: bitmask }); + } + AnnotationKind::Observable { measurement_nodes, .. } => { + let bitmask = measurement_nodes_to_aux_bitmask( + measurement_nodes, tc, expanded, num_meas, + ); + observables.push(Observable { id: observables.len(), pauli: bitmask }); + } + AnnotationKind::Operator => {} + } + } + + (detectors, observables) +} + +/// Map measurement record indices to a Z bitmask on auxiliary qubits. +/// +/// Each measurement_node is a measurement record index (counting all +/// MZ qubits in circuit order). Maps directly to an auxiliary qubit +/// in the expanded circuit via `expanded.measurement_qubit[record]`. +fn measurement_nodes_to_aux_bitmask( + measurement_nodes: &[usize], + _tc: &TickCircuit, + expanded: &expand::ExpandedCircuit, + num_meas: usize, +) -> Bm { + let mut bitmask = Bm::default(); + + for &record_idx in measurement_nodes { + if record_idx < num_meas { + let aux_qubit = expanded.measurement_qubit[record_idx]; + bitmask.z_bits.xor_bit(aux_qubit); + } + } + + bitmask +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_empty_no_noise() { + let mut tc = TickCircuit::new(); + tc.tick().pz(&[0]); + tc.tick().mz(&[0]); + let entries = EegDemBuilder::from_tick_circuit(&tc) + .noise(NoiseModel::coherent_only(0.0)) + .build(); + assert!(entries.is_empty()); + } + + #[test] + fn test_summary_coherent() { + let mut tc = TickCircuit::new(); + tc.tick().pz(&[0, 1]); + tc.tick().h(&[0]); + tc.tick().cx(&[(0, 1)]); + tc.tick().mz(&[0, 1]); + let summary = EegDemBuilder::from_tick_circuit(&tc) + .noise(NoiseModel::coherent_only(0.1)) + .summary(); + assert!(summary.num_h_generators > 0); + assert_eq!(summary.num_s_generators, 0); + } + + #[test] + fn test_builder_matches_manual_pipeline() { + // Same circuit through builder and manual pipeline should give same DEM + let mut tc = TickCircuit::new(); + tc.tick().pz(&[0, 1]); + tc.tick().h(&[0]); + tc.tick().cx(&[(0, 1)]); + tc.tick().mz(&[0, 1]); + + let noise = NoiseModel::coherent_only(0.05); + + // Builder path + let builder_entries = EegDemBuilder::from_tick_circuit(&tc) + .noise(noise.clone()) + .build(); + + // Manual path + let gates: Vec = tc.iter_gates().cloned().collect(); + let expanded = expand::expand_circuit(&gates); + let result = circuit::analyze_expanded(&expanded.gates, &noise); + + let expanded_pre = exclude_final_mz(&expanded.gates); + let stab_group = StabilizerGroup::from_circuit( + &expanded_pre, expanded.num_qubits, + ); + + let (detectors, observables) = build_detectors(&tc, &expanded); + let manual_entries = dem_mapping::build_dem_with_stabilizers( + &result.generators, &detectors, &observables, + Some(&stab_group), + ); + + // Same number of entries + assert_eq!(builder_entries.len(), manual_entries.len(), + "Builder and manual should produce same number of DEM entries"); + + // Same probabilities (order may differ, so sort) + let mut bp: Vec = builder_entries.iter().map(|e| e.probability).collect(); + let mut mp: Vec = manual_entries.iter().map(|e| e.probability).collect(); + bp.sort_by(|a, b| a.partial_cmp(b).unwrap()); + mp.sort_by(|a, b| a.partial_cmp(b).unwrap()); + for (b, m) in bp.iter().zip(mp.iter()) { + assert!((b - m).abs() < 1e-15, + "Probability mismatch: builder={b}, manual={m}"); + } + } + + #[test] + fn test_no_annotations_empty_dem() { + // Without detector/observable annotations, builder should produce empty DEM + let mut tc = TickCircuit::new(); + tc.tick().pz(&[0, 1]); + tc.tick().cx(&[(0, 1)]); + tc.tick().mz(&[0, 1]); + + let entries = EegDemBuilder::from_tick_circuit(&tc) + .noise(NoiseModel::depolarizing(0.01)) + .build(); + + assert!(entries.is_empty(), + "No annotations → no detectors → no DEM entries"); + } + + #[test] + fn test_with_detector_annotations() { + // Build a circuit with detector annotations + let mut tc = TickCircuit::new(); + tc.tick().pz(&[0, 1, 2]); + + // Round 1: syndrome extraction + tc.tick().cx(&[(0, 2)]); + tc.tick().cx(&[(1, 2)]); + let m1 = tc.tick().mz(&[2]); + + // Round 2: syndrome extraction + tc.tick().pz(&[2]); + tc.tick().cx(&[(0, 2)]); + tc.tick().cx(&[(1, 2)]); + let m2 = tc.tick().mz(&[2]); + + // Detector: compare m1 and m2 + tc.detector(&[m1[0], m2[0]]); + + // Final readout + tc.tick().mz(&[0, 1]); + + let entries = EegDemBuilder::from_tick_circuit(&tc) + .noise(NoiseModel::depolarizing(0.01)) + .build(); + + assert!(!entries.is_empty(), + "Circuit with detector annotation should produce DEM entries"); + for e in &entries { + assert!(e.probability > 0.0); + assert!(e.probability < 0.5); + } + } + + #[test] + fn test_summary_counts() { + let mut tc = TickCircuit::new(); + tc.tick().pz(&[0, 1, 2]); + tc.tick().cx(&[(0, 1)]); + tc.tick().cx(&[(1, 2)]); + tc.tick().mz(&[0, 1, 2]); + + let summary = EegDemBuilder::from_tick_circuit(&tc) + .noise(NoiseModel::depolarizing(0.01).with_idle_rz(0.05)) + .summary(); + + assert!(summary.num_h_generators > 0, "Should have H generators from idle RZ"); + assert!(summary.num_s_generators > 0, "Should have S generators from depolarizing"); + assert_eq!(summary.num_expanded_qubits, 6, "3 original + 3 aux"); + } +} diff --git a/exp/pecos-eeg/src/circuit.rs b/exp/pecos-eeg/src/circuit.rs new file mode 100644 index 000000000..e4bb1dbec --- /dev/null +++ b/exp/pecos-eeg/src/circuit.rs @@ -0,0 +1,587 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! EEG circuit analysis on the expanded (measurement-deferred) circuit. +//! +//! After expansion, the circuit is purely Clifford. Error generators are +//! propagated straight to the end via Clifford conjugation (no measurement +//! absorption). At the end, each Pauli P flips measurement k iff P has +//! X on measurement_qubit[k]. + +use crate::Bm; +use crate::eeg::EegType; +use pecos_core::gate_type::GateType; +use pecos_core::pauli::pauli_bitmask::*; +use pecos_core::Gate; + +/// Noise model parameters. +#[derive(Clone, Debug)] +pub struct NoiseModel { + /// Coherent RZ angle (radians) on both qubits after each 2-qubit gate. + pub idle_rz: f64, + /// Single-qubit depolarizing probability. + pub p1: f64, + /// Two-qubit depolarizing probability. + pub p2: f64, + /// Measurement bit-flip probability. + pub p_meas: f64, + /// Preparation error probability. + pub p_prep: f64, +} + +impl NoiseModel { + #[must_use] + pub fn coherent_only(idle_rz: f64) -> Self { + Self { idle_rz, p1: 0.0, p2: 0.0, p_meas: 0.0, p_prep: 0.0 } + } + + #[must_use] + pub fn depolarizing(p: f64) -> Self { + Self { idle_rz: 0.0, p1: p, p2: p, p_meas: p, p_prep: p } + } + + #[must_use] + pub fn with_idle_rz(mut self, angle: f64) -> Self { + self.idle_rz = angle; + self + } +} + +/// Identifies the physical noise source that produced a generator. +#[derive(Clone, Debug, PartialEq, Eq, Hash)] +pub struct NoiseSource { + /// Index of the gate in the expanded circuit that the noise follows. + pub gate_index: usize, + /// Qubit the noise acts on (for per-qubit noise like idle RZ). + pub qubit: usize, +} + +/// A propagated EEG generator at the end of the expanded circuit. +#[derive(Clone, Debug)] +pub struct PropagatedEeg { + /// EEG type (H, S, C, or A). + pub eeg_type: EegType, + /// Primary Pauli label at end of circuit. + pub label: Bm, + /// Second Pauli label for C and A types (None for H and S). + pub label2: Option, + /// Coefficient (rate). For H: includes sign from conjugation. For S: always negative. + pub coeff: f64, + /// Physical noise source that produced this generator (for sensitivity analysis). + pub source: Option, +} + +/// Result of EEG analysis on the expanded circuit. +#[derive(Clone, Debug)] +pub struct EegAnalysisResult { + /// All propagated generators at end of circuit. + pub generators: Vec, + /// Number of measurement records. + pub num_measurements: usize, +} + +impl EegAnalysisResult { + /// Generator fidelity ε_gen = Σ h_P² + Σ |s_P| (Hines Eq. 2/Eq. 6). + /// + /// Measures the total "size" of the error. The DEM prediction error + /// (TVD) scales as ε_gen^{1.5}. + #[must_use] + pub fn generator_fidelity(&self) -> f64 { + let mut eps = 0.0; + for g in &self.generators { + match g.eeg_type { + EegType::H => eps += g.coeff * g.coeff, + EegType::S => eps += g.coeff.abs(), + _ => {} + } + } + eps + } +} + +/// Analyze the expanded circuit with a flexible noise specification. +/// +/// For each gate, calls `noise.noise_after_gate()` to get generators, +/// then propagates them to the end via Clifford conjugation. +/// +/// Expansion gates (QAlloc, expansion CX, expansion PZ) are skipped +/// for noise injection. +pub fn analyze_with_noise(gates: &[Gate], noise: &dyn crate::noise::NoiseSpec) -> EegAnalysisResult { + let mut generators = Vec::new(); + let mut num_measurements = 0; + + // Build sets of expansion gate indices + let mut expansion_cx_indices = std::collections::HashSet::new(); + let mut expansion_pz_indices = std::collections::HashSet::new(); + for i in 1..gates.len() { + if gates[i].gate_type == GateType::CX && gates[i - 1].gate_type == GateType::QAlloc { + let alloc_q = gates[i - 1].qubits[0].index(); + if gates[i].qubits.len() >= 2 && gates[i].qubits[1].index() == alloc_q { + expansion_cx_indices.insert(i); + if i + 1 < gates.len() && gates[i + 1].gate_type == GateType::PZ { + let cx_control = gates[i].qubits[0].index(); + if gates[i + 1].qubits.len() == 1 + && gates[i + 1].qubits[0].index() == cx_control + { + expansion_pz_indices.insert(i + 1); + } + } + } + } + } + + for (i, gate) in gates.iter().enumerate() { + let remaining = &gates[i + 1..]; + let qubits: Vec = gate.qubits.iter().map(|q| q.index()).collect(); + + // Skip expansion gates (virtual, not physical) + let is_expansion = expansion_cx_indices.contains(&i) + || expansion_pz_indices.contains(&i) + || gate.gate_type == GateType::QAlloc; + + if !is_expansion { + // Get noise generators from the noise specification + let injections = noise.noise_after_gate(i, gate.gate_type, &qubits); + + for inj in injections { + match inj.eeg_type { + EegType::H => { + let (pl, coeff) = propagate_h(inj.label, inj.rate, remaining); + generators.push(PropagatedEeg { + eeg_type: EegType::H, label: pl, label2: None, coeff, + source: Some(NoiseSource { gate_index: i, qubit: qubits.first().copied().unwrap_or(0) }), + }); + } + EegType::S => { + let (pl, _) = propagate_s(inj.label, remaining); + generators.push(PropagatedEeg { + eeg_type: EegType::S, label: pl, label2: None, coeff: inj.rate, + source: None, + }); + } + EegType::C | EegType::A => { + if let Some(label2) = inj.label2 { + let (l1, l2, coeff) = propagate_ca(inj.label, label2, inj.rate, remaining); + generators.push(PropagatedEeg { + eeg_type: inj.eeg_type, label: l1, label2: Some(l2), coeff, + source: None, + }); + } + } + } + } + } + + // Handle explicit RZ gates (from the circuit, not noise model) + if gate.gate_type == GateType::RZ { + if let Some(&angle) = gate.angles.first() { + for &q in &qubits { + let label = Bm::z(q); + let (pl, coeff) = propagate_h(label, angle.to_radians() / 2.0, remaining); + generators.push(PropagatedEeg { + eeg_type: EegType::H, label: pl, label2: None, coeff, + source: Some(NoiseSource { gate_index: i, qubit: q }), + }); + } + } + } + + // Count measurements + if gate.gate_type == GateType::MZ { + num_measurements += qubits.len(); + } + } + + EegAnalysisResult { generators, num_measurements } +} + +/// Analyze the expanded circuit with the legacy NoiseModel. +/// +/// Delegates to `analyze_with_noise` using a `UniformNoise` specification. +pub fn analyze_expanded(gates: &[Gate], noise: &NoiseModel) -> EegAnalysisResult { + let uniform = crate::noise::UniformNoise { + idle_rz: noise.idle_rz, + p1: noise.p1, + p2: noise.p2, + p_meas: noise.p_meas, + p_prep: noise.p_prep, + }; + analyze_with_noise(gates, &uniform) +} + +/// Propagate H_P forward: sign changes under Clifford conjugation. +/// PZ/QAlloc clears all Pauli components on the reset qubit. +fn propagate_h(mut label: Bm, mut coeff: f64, remaining: &[Gate]) -> (Bm, f64) { + for gate in remaining { + match gate.gate_type { + GateType::PZ | GateType::QAlloc => { + // Reset removes any error on this qubit + for q in &gate.qubits { + label.x_bits.clear_bit(q.index()); + label.z_bits.clear_bit(q.index()); + } + } + _ => { + if let Some(r) = conjugate_by_gate(&label, gate) { + label = r.label; + if r.sign_negative { coeff = -coeff; } + } + } + } + } + (label, coeff) +} + +/// Propagate C_{P,Q} or A_{P,Q} forward: both labels conjugate, signs multiply. +/// gamma(C_{P,Q}, U) = s_{U,P} * s_{U,Q}. Same for A. +/// PZ/QAlloc clears components on both labels. +fn propagate_ca( + mut label1: Bm, + mut label2: Bm, + mut coeff: f64, + remaining: &[Gate], +) -> (Bm, Bm, f64) { + for gate in remaining { + match gate.gate_type { + GateType::PZ | GateType::QAlloc => { + for q in &gate.qubits { + label1.x_bits.clear_bit(q.index()); + label1.z_bits.clear_bit(q.index()); + label2.x_bits.clear_bit(q.index()); + label2.z_bits.clear_bit(q.index()); + } + } + _ => { + let mut sign = false; + if let Some(r) = conjugate_by_gate(&label1, gate) { + label1 = r.label; + if r.sign_negative { sign = !sign; } + } + if let Some(r) = conjugate_by_gate(&label2, gate) { + label2 = r.label; + if r.sign_negative { sign = !sign; } + } + if sign { coeff = -coeff; } + } + } + } + (label1, label2, coeff) +} + +/// Propagate S_P forward: no sign change (gamma(S_P, U) = 1 always). +/// PZ/QAlloc clears all Pauli components on the reset qubit. +fn propagate_s(mut label: Bm, remaining: &[Gate]) -> (Bm, f64) { + for gate in remaining { + match gate.gate_type { + GateType::PZ | GateType::QAlloc => { + for q in &gate.qubits { + label.x_bits.clear_bit(q.index()); + label.z_bits.clear_bit(q.index()); + } + } + _ => { + if let Some(r) = conjugate_by_gate(&label, gate) { + label = r.label; + } + } + } + } + (label, 0.0) +} + +fn conjugate_by_gate(label: &Bm, gate: &Gate) -> Option>> { + if gate.qubits.is_empty() { return None; } + let q0 = || gate.qubits[0].index(); + let q1 = || gate.qubits[1].index(); + match gate.gate_type { + GateType::H => Some(conjugate_h(label, q0())), + GateType::SZ => Some(conjugate_sz(label, q0())), + GateType::SZdg => Some(conjugate_szdg(label, q0())), + GateType::SX => Some(conjugate_sx(label, q0())), + GateType::SXdg => Some(conjugate_sxdg(label, q0())), + GateType::SY => Some(conjugate_sy(label, q0())), + GateType::SYdg => Some(conjugate_sydg(label, q0())), + GateType::X => Some(conjugate_x(label, q0())), + GateType::Y => Some(conjugate_y(label, q0())), + GateType::Z => Some(conjugate_z(label, q0())), + GateType::CX => Some(conjugate_cx(label, q0(), q1())), + GateType::CY => Some(conjugate_cy(label, q0(), q1())), + GateType::CZ => Some(conjugate_cz(label, q0(), q1())), + GateType::SWAP => Some(conjugate_swap(label, q0(), q1())), + _ => None, + } +} + +#[cfg(test)] +mod tests { + use super::*; + use pecos_core::{GateQubits, GateAngles, GateParams, QubitId}; + + fn gate(gt: GateType, qubits: &[usize]) -> Gate { + Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), + } + } + + #[test] + fn test_rz_rate_is_half_theta() { + // Idle RZ(0.1) after CX: rate should be 0.05 (theta/2) + // because RZ(theta) = exp(-i*theta*Z/2) → H_Z with rate theta/2 + let gates = vec![ + gate(GateType::CX, &[0, 1]), + ]; + let noise = NoiseModel::coherent_only(0.1); + let result = analyze_expanded(&gates, &noise); + + let h_gens: Vec<_> = result.generators.iter() + .filter(|g| g.eeg_type == EegType::H) + .collect(); + assert_eq!(h_gens.len(), 2); + for g in &h_gens { + assert!((g.coeff.abs() - 0.05).abs() < 1e-10, + "Rate should be 0.05 (theta/2), got {}", g.coeff); + } + } + + #[test] + fn test_h_propagation_through_hadamard() { + // H_Z after H gate: Z → X, sign positive + let gates = vec![ + gate(GateType::CX, &[0, 1]), + gate(GateType::H, &[0]), + ]; + let noise = NoiseModel::coherent_only(0.1); + let result = analyze_expanded(&gates, &noise); + + let q0_gen = result.generators.iter() + .find(|g| g.eeg_type == EegType::H && g.label.has_x(0)) + .expect("Should have H_X on qubit 0"); + assert!((q0_gen.coeff - 0.05).abs() < 1e-10, "H: Z→X, rate=theta/2=0.05"); + } + + #[test] + fn test_sx_propagation() { + // SX on qubit 1 after CX: Z1 → -Y1 (sign flip) + let gates = vec![ + gate(GateType::CX, &[0, 1]), + gate(GateType::SX, &[1]), + ]; + let noise = NoiseModel::coherent_only(0.1); + let result = analyze_expanded(&gates, &noise); + + // H_Z(1) propagated through SX(1): Z→-Y, coeff flips sign + let q1_gen = result.generators.iter() + .find(|g| g.eeg_type == EegType::H && g.label.has_x(1) && g.label.has_z(1)) + .expect("Should have H_Y on qubit 1 after SX"); + assert!((q1_gen.coeff + 0.05).abs() < 1e-10, + "SX: Z→-Y, sign flips: expected -0.05, got {}", q1_gen.coeff); + + // H_Z(0) should be unaffected by SX on qubit 1 + let q0_gen = result.generators.iter() + .find(|g| g.eeg_type == EegType::H && g.label == Bm::z(0)) + .expect("Should still have H_Z on qubit 0"); + assert!((q0_gen.coeff - 0.05).abs() < 1e-10); + } + + #[test] + fn test_cy_propagation() { + // CY after CX: Z on target propagates like CX (Z_t → Z_c Z_t) + let gates = vec![ + gate(GateType::CX, &[0, 1]), + gate(GateType::CY, &[0, 1]), + ]; + let noise = NoiseModel::coherent_only(0.1); + let result = analyze_expanded(&gates, &noise); + + // H_Z(1) from CX, propagated through CY: Z_t → Z_c Z_t + let zz_gen = result.generators.iter() + .find(|g| g.eeg_type == EegType::H + && g.label == Bm::z(0).multiply(&Bm::z(1))) + .expect("Should have Z0Z1 after CY propagation of Z1"); + assert!((zz_gen.coeff.abs() - 0.05).abs() < 1e-10); + } + + #[test] + fn test_sy_propagation() { + // SY: X→-Z, Z→X. So H_Z through SY gives H_X with no sign flip + let gates = vec![ + gate(GateType::CX, &[0, 1]), + gate(GateType::SY, &[1]), + ]; + let noise = NoiseModel::coherent_only(0.1); + let result = analyze_expanded(&gates, &noise); + + // H_Z(1) through SY(1): Z→X, no sign flip + let q1_gen = result.generators.iter() + .find(|g| g.eeg_type == EegType::H && g.label == Bm::x(1)) + .expect("Should have H_X on qubit 1 after SY"); + assert!((q1_gen.coeff - 0.05).abs() < 1e-10, + "SY: Z→X, no sign: expected 0.05, got {}", q1_gen.coeff); + } + + #[test] + fn test_pz_clears_propagated_errors() { + // Error injected before PZ should be cleared + let gates = vec![ + gate(GateType::CX, &[0, 1]), + gate(GateType::PZ, &[1]), // Reset qubit 1 + ]; + let noise = NoiseModel::coherent_only(0.1); + let result = analyze_expanded(&gates, &noise); + + // H_Z(1) should be cleared by PZ(1) + let q1_gens: Vec<_> = result.generators.iter() + .filter(|g| g.eeg_type == EegType::H && (g.label.has_x(1) || g.label.has_z(1))) + .collect(); + assert!(q1_gens.is_empty(), + "PZ should clear all error components on qubit 1"); + + // H_Z(0) should survive (PZ on qubit 1 doesn't touch qubit 0) + let q0_gen = result.generators.iter() + .find(|g| g.eeg_type == EegType::H && g.label == Bm::z(0)); + assert!(q0_gen.is_some(), "H_Z(0) should survive PZ(1)"); + } + + #[test] + fn test_no_noise_no_generators() { + let gates = vec![ + gate(GateType::CX, &[0, 1]), + gate(GateType::H, &[0]), + ]; + let noise = NoiseModel::coherent_only(0.0); + let result = analyze_expanded(&gates, &noise); + assert!(result.generators.is_empty()); + } + + #[test] + fn test_depol_1q_injects_three_paulis() { + // Single-qubit depolarizing on H gate produces S_X, S_Y, S_Z + let gates = vec![gate(GateType::H, &[0])]; + let noise = NoiseModel { idle_rz: 0.0, p1: 0.03, p2: 0.0, p_meas: 0.0, p_prep: 0.0 }; + let result = analyze_expanded(&gates, &noise); + + let s_gens: Vec<_> = result.generators.iter() + .filter(|g| g.eeg_type == EegType::S) + .collect(); + assert_eq!(s_gens.len(), 3, "1q depolarizing should inject 3 S generators"); + for g in &s_gens { + assert!((g.coeff + 0.01).abs() < 1e-10, "Rate should be -p/3 = -0.01"); + } + } + + #[test] + fn test_depol_2q_injects_fifteen_paulis() { + // Two-qubit depolarizing on CX: 15 S generators (3 single + 3 single + 9 tensor) + let gates = vec![gate(GateType::CX, &[0, 1])]; + let noise = NoiseModel { idle_rz: 0.0, p1: 0.0, p2: 0.15, p_meas: 0.0, p_prep: 0.0 }; + let result = analyze_expanded(&gates, &noise); + + let s_gens: Vec<_> = result.generators.iter() + .filter(|g| g.eeg_type == EegType::S) + .collect(); + assert_eq!(s_gens.len(), 15, "2q depolarizing should inject 15 S generators"); + for g in &s_gens { + assert!((g.coeff + 0.01).abs() < 1e-10, "Rate should be -p/15 = -0.01"); + } + } + + #[test] + fn test_meas_noise_injects_sx() { + // Measurement error produces S_X on the measured qubit + let gates = vec![gate(GateType::MZ, &[0])]; + let noise = NoiseModel { idle_rz: 0.0, p1: 0.0, p2: 0.0, p_meas: 0.05, p_prep: 0.0 }; + let result = analyze_expanded(&gates, &noise); + + let s_gens: Vec<_> = result.generators.iter() + .filter(|g| g.eeg_type == EegType::S) + .collect(); + assert_eq!(s_gens.len(), 1); + assert_eq!(s_gens[0].label, Bm::x(0)); + assert!((s_gens[0].coeff + 0.05).abs() < 1e-10); + } + + #[test] + fn test_prep_noise_injects_sx() { + // Preparation error: S_X after PZ + let gates = vec![gate(GateType::PZ, &[0])]; + let noise = NoiseModel { idle_rz: 0.0, p1: 0.0, p2: 0.0, p_meas: 0.0, p_prep: 0.03 }; + let result = analyze_expanded(&gates, &noise); + + let s_gens: Vec<_> = result.generators.iter() + .filter(|g| g.eeg_type == EegType::S) + .collect(); + assert_eq!(s_gens.len(), 1); + assert!((s_gens[0].coeff + 0.03).abs() < 1e-10); + } + + #[test] + fn test_expansion_pz_gets_no_prep_noise() { + // Expansion PZ (measurement projection) should NOT inject prep noise. + // Circuit: PZ(0,1), H(1), CX(1,0), MZ(1), PZ(1), H(1), CX(1,0), MZ(1), MZ(0) + // With p_prep > 0: only the original PZ gates should inject noise. + let original_gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::H, &[1]), + gate(GateType::CX, &[1, 0]), + gate(GateType::MZ, &[1]), + gate(GateType::PZ, &[1]), // original reset + gate(GateType::H, &[1]), + gate(GateType::CX, &[1, 0]), + gate(GateType::MZ, &[1]), // last round + gate(GateType::MZ, &[0]), + ]; + let expanded = crate::expand::expand_circuit(&original_gates); + + // Count PZ gates in expanded circuit (originals + expansion projections) + let all_pz: Vec<_> = expanded.gates.iter() + .filter(|g| g.gate_type == GateType::PZ) + .collect(); + + // With prep noise: count S generators from prep + let noise = NoiseModel { idle_rz: 0.0, p1: 0.0, p2: 0.0, p_meas: 0.0, p_prep: 0.1 }; + let result = analyze_expanded(&expanded.gates, &noise); + + let prep_gens: Vec<_> = result.generators.iter() + .filter(|g| g.eeg_type == EegType::S) + .collect(); + + // Original PZ gates: PZ(0) init, PZ(1) init, PZ(1) reset = 3 PZ with noise + // Expansion PZ: should NOT inject noise + // Each original PZ injects 1 S generator (S_X) + assert_eq!(prep_gens.len(), 3, + "Only original PZ should inject prep noise, not expansion PZ. \ + Got {} S generators, total PZ gates in expanded: {}", + prep_gens.len(), all_pz.len()); + } + + #[test] + fn test_expansion_cx_gets_no_noise() { + // The CX gates added by expansion (deferred measurement) should not get noise. + // Circuit: PZ(0), CX(0,1), MZ(0), MZ(1) + // Expanded: PZ(0), CX(0,1), QAlloc(2), CX(0,2), QAlloc(3), CX(1,3), MZ(2), MZ(3) + // Only CX(0,1) should get noise, not CX(0,2) or CX(1,3). + let gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::CX, &[0, 1]), + gate(GateType::MZ, &[0]), + gate(GateType::MZ, &[1]), + ]; + let expanded = crate::expand::expand_circuit(&gates); + let noise = NoiseModel::coherent_only(0.1); + let result = analyze_expanded(&expanded.gates, &noise); + + let h_gens: Vec<_> = result.generators.iter() + .filter(|g| g.eeg_type == EegType::H) + .collect(); + // Only 2 H generators from the original CX (one per qubit) + assert_eq!(h_gens.len(), 2, + "Only original CX should get noise, not expansion CX gates"); + } +} diff --git a/exp/pecos-eeg/src/coherent_dem.rs b/exp/pecos-eeg/src/coherent_dem.rs new file mode 100644 index 000000000..2749a8d62 --- /dev/null +++ b/exp/pecos-eeg/src/coherent_dem.rs @@ -0,0 +1,821 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Coherent DEM builder via backward Heisenberg mechanism extraction. +//! +//! Walks each noise source backward through the circuit to determine its +//! effective Pauli label at each detector. Groups noise sources by their +//! effective label (= same DEM mechanism), accumulates coherent amplitudes, +//! and computes mechanism probabilities. +//! +//! For H-type (coherent) noise: amplitudes add, probability = sin²(total). +//! For S-type (stochastic) noise: rates add, probability = (1-exp(2·total))/2. + +use crate::Bm; +use crate::dem_mapping::{DecomposableDemEntry, DemEntry, DemEvent, Detector, Observable}; +use crate::heisenberg::{SparsePauli, sparse_conjugate}; +use crate::eeg::EegType; +use crate::noise::NoiseSpec; +use pecos_core::Gate; +use pecos_core::pauli::pauli_bitmask::BitmaskStorage; +use smallvec::SmallVec; +use std::collections::BTreeMap; + +/// A noise contribution at a specific gate. +struct NoiseContribution { + /// Effective Pauli label after backward propagation. + label: Bm, + /// EEG type (H or S). + eeg_type: EegType, + /// Amplitude or rate. + value: f64, +} + +/// Build a coherent DEM by extracting mechanisms from backward propagation. +/// +/// For each noise injection point in the expanded circuit, propagates +/// its Pauli label backward to the detector measurement point. Noise +/// sources that produce the same effective Pauli label are grouped into +/// a single DEM mechanism with coherently accumulated amplitude. +/// +/// This gives both correct mechanism structure AND correct coherent +/// probabilities from a single framework. +pub fn build_coherent_dem( + gates: &[Gate], + noise: &dyn NoiseSpec, + detectors: &[Detector], + observables: &[Observable], + expansion_gates: &[bool], +) -> Vec { + // Step 1: Collect all noise sources and their Pauli labels + let mut noise_sources: Vec<(usize, NoiseContribution)> = Vec::new(); + + for (gate_idx, gate) in gates.iter().enumerate() { + if gate_idx < expansion_gates.len() && expansion_gates[gate_idx] { + continue; + } + let qubits: SmallVec<[usize; 4]> = gate.qubits.iter().map(|q| q.index()).collect(); + let injections = noise.noise_after_gate(gate_idx, gate.gate_type, &qubits); + + for inj in injections { + noise_sources.push((gate_idx, NoiseContribution { + label: inj.label.clone(), + eeg_type: inj.eeg_type, + value: inj.rate, + })); + } + } + + // Step 2: For each noise source, determine which detectors it affects + // by checking if its Pauli label, after backward propagation through + // the circuit, anticommutes with each detector's stabilizer. + // + // Rather than propagating each noise label forward (expensive), we use + // the detectors' stabilizers propagated backward to each noise location. + // For each detector, we run the backward Heisenberg walk and at each + // noise source check anticommutation. If the backward-propagated + // stabilizer anticommutes with the noise label at that gate, the noise + // source affects that detector. + // + // We compute this per-detector, then group noise sources by which + // detectors they affect. + + // For each noise source: which detectors and observables it flips + let num_noise = noise_sources.len(); + let mut noise_det_sets: Vec> = vec![SmallVec::new(); num_noise]; + let mut noise_obs_sets: Vec> = vec![SmallVec::new(); num_noise]; + + // Build gate_index -> noise_source_indices map (shared across all walks) + let mut gate_to_noise: BTreeMap> = BTreeMap::new(); + for (ns_idx, (gate_idx, _)) in noise_sources.iter().enumerate() { + gate_to_noise.entry(*gate_idx).or_default().push(ns_idx); + } + + // Helper: propagate a stabilizer/observable backward and record + // which noise sources anticommute with it. + let backward_classify = |stabilizer: &Bm| -> Vec { + let mut prop = stabilizer.clone(); + let mut hits = vec![false; num_noise]; + + for gate_idx in (0..gates.len()).rev() { + // Check noise sources BEFORE undoing the gate + if let Some(ns_indices) = gate_to_noise.get(&gate_idx) { + for &ns_idx in ns_indices { + if !prop.commutes_with(&noise_sources[ns_idx].1.label) { + hits[ns_idx] = true; + } + } + } + backward_conjugate_bm(&mut prop, &gates[gate_idx]); + } + + hits + }; + + // Classify: which detectors does each noise source flip? + for det in detectors { + let hits = backward_classify(&det.stabilizer); + for (ns_idx, &hit) in hits.iter().enumerate() { + if hit { + noise_det_sets[ns_idx].push(det.id); + } + } + } + + // Classify: which observables does each noise source flip? + for obs in observables { + let hits = backward_classify(&obs.pauli); + for (ns_idx, &hit) in hits.iter().enumerate() { + if hit { + noise_obs_sets[ns_idx].push(obs.id); + } + } + } + + // Step 3: Group noise sources by (detector_set, observable_set, eeg_type, label). + // + // For H-type: only noise sources with the SAME Pauli label accumulate + // coherently. Different labels (e.g., Z on qubit 1 vs Z on qubit 2) + // are separate mechanisms even if they flip the same detectors. + // + // For S-type: same grouping — different Pauli types at the same location + // are independent mechanisms. + // + // After coherent accumulation per label, mechanisms with the same + // detector set are combined independently (product formula). + let mut h_groups: BTreeMap<(DemEvent, Bm), f64> = BTreeMap::new(); + let mut s_groups: BTreeMap<(DemEvent, Bm), f64> = BTreeMap::new(); + + for (ns_idx, (_, contrib)) in noise_sources.iter().enumerate() { + let dets = &noise_det_sets[ns_idx]; + let obs = &noise_obs_sets[ns_idx]; + if dets.is_empty() && obs.is_empty() { + continue; + } + + let event = DemEvent { + detectors: dets.clone(), + observables: obs.clone(), + }; + + let key = (event, contrib.label.clone()); + match contrib.eeg_type { + EegType::H => { + *h_groups.entry(key).or_insert(0.0) += contrib.value; + } + EegType::S => { + *s_groups.entry(key).or_insert(0.0) += contrib.value; + } + _ => {} + } + } + + // Step 4: Compute approximate probabilities per mechanism + let mut entries = Vec::new(); + + for ((event, _label), total_h) in &h_groups { + let prob = total_h.sin().powi(2); + if prob > 1e-15 { + entries.push(DemEntry { event: event.clone(), probability: prob }); + } + } + + for ((event, _label), total_s) in &s_groups { + let prob = (1.0 - (2.0 * total_s).exp()) / 2.0; + if prob.abs() > 1e-15 { + entries.push(DemEntry { event: event.clone(), probability: prob.abs() }); + } + } + + merge_dem_entries(entries) +} + +/// Build a coherent DEM with X/Z decomposition info for MWPM decoders. +/// +/// Same mechanism extraction as `build_coherent_dem`, but additionally +/// splits each Pauli label into X-only and Z-only components and checks +/// anticommutation separately. This produces `DecomposableDemEntry`s +/// that know which detectors each component flips, enabling proper +/// graphlike decomposition for pymatching. +pub fn build_coherent_dem_decomposable( + gates: &[Gate], + noise: &dyn NoiseSpec, + detectors: &[Detector], + observables: &[Observable], + expansion_gates: &[bool], +) -> Vec { + // Step 1: Collect noise sources (same as build_coherent_dem) + let mut noise_sources: Vec<(usize, NoiseContribution)> = Vec::new(); + + for (gate_idx, gate) in gates.iter().enumerate() { + if gate_idx < expansion_gates.len() && expansion_gates[gate_idx] { + continue; + } + let qubits: SmallVec<[usize; 4]> = gate.qubits.iter().map(|q| q.index()).collect(); + let injections = noise.noise_after_gate(gate_idx, gate.gate_type, &qubits); + + for inj in injections { + noise_sources.push((gate_idx, NoiseContribution { + label: inj.label.clone(), + eeg_type: inj.eeg_type, + value: inj.rate, + })); + } + } + + let num_noise = noise_sources.len(); + + // For each noise source: full, X-only, and Z-only detector/observable sets + let mut noise_det_sets: Vec> = vec![SmallVec::new(); num_noise]; + let mut noise_obs_sets: Vec> = vec![SmallVec::new(); num_noise]; + let mut noise_x_det_sets: Vec> = vec![SmallVec::new(); num_noise]; + let mut noise_x_obs_sets: Vec> = vec![SmallVec::new(); num_noise]; + let mut noise_z_det_sets: Vec> = vec![SmallVec::new(); num_noise]; + let mut noise_z_obs_sets: Vec> = vec![SmallVec::new(); num_noise]; + + // Precompute X-only and Z-only labels for each noise source + let noise_x_labels: Vec = noise_sources.iter().map(|(_, c)| { + let mut x_only = Bm::default(); + x_only.x_bits = c.label.x_bits.clone(); + // z_bits stays zero + x_only + }).collect(); + let noise_z_labels: Vec = noise_sources.iter().map(|(_, c)| { + let mut z_only = Bm::default(); + z_only.z_bits = c.label.z_bits.clone(); + // x_bits stays zero + z_only + }).collect(); + + // Build gate -> noise source index map + let mut gate_to_noise: BTreeMap> = BTreeMap::new(); + for (ns_idx, (gate_idx, _)) in noise_sources.iter().enumerate() { + gate_to_noise.entry(*gate_idx).or_default().push(ns_idx); + } + + // Step 2: Backward walk — check anticommutation with full, X-only, Z-only labels + let backward_classify_xz = |stabilizer: &Bm| -> (Vec, Vec, Vec) { + let mut prop = stabilizer.clone(); + let mut hits_full = vec![false; num_noise]; + let mut hits_x = vec![false; num_noise]; + let mut hits_z = vec![false; num_noise]; + + for gate_idx in (0..gates.len()).rev() { + if let Some(ns_indices) = gate_to_noise.get(&gate_idx) { + for &ns_idx in ns_indices { + // Full anticommutation + if !prop.commutes_with(&noise_sources[ns_idx].1.label) { + hits_full[ns_idx] = true; + } + // X-only: ⟨S, P_X⟩ = S_Z · P_X + // P_X has no Z bits, so anticommutation only from S_Z * P_X + if !noise_x_labels[ns_idx].x_bits.is_zero() + && !prop.commutes_with(&noise_x_labels[ns_idx]) + { + hits_x[ns_idx] = true; + } + // Z-only: ⟨S, P_Z⟩ = S_X · P_Z + // P_Z has no X bits, so anticommutation only from S_X * P_Z + if !noise_z_labels[ns_idx].z_bits.is_zero() + && !prop.commutes_with(&noise_z_labels[ns_idx]) + { + hits_z[ns_idx] = true; + } + } + } + backward_conjugate_bm(&mut prop, &gates[gate_idx]); + } + + (hits_full, hits_x, hits_z) + }; + + // Classify detectors + for det in detectors { + let (hits_full, hits_x, hits_z) = backward_classify_xz(&det.stabilizer); + for ns_idx in 0..num_noise { + if hits_full[ns_idx] { noise_det_sets[ns_idx].push(det.id); } + if hits_x[ns_idx] { noise_x_det_sets[ns_idx].push(det.id); } + if hits_z[ns_idx] { noise_z_det_sets[ns_idx].push(det.id); } + } + } + + // Classify observables + for obs in observables { + let (hits_full, hits_x, hits_z) = backward_classify_xz(&obs.pauli); + for ns_idx in 0..num_noise { + if hits_full[ns_idx] { noise_obs_sets[ns_idx].push(obs.id); } + if hits_x[ns_idx] { noise_x_obs_sets[ns_idx].push(obs.id); } + if hits_z[ns_idx] { noise_z_obs_sets[ns_idx].push(obs.id); } + } + } + + // Step 3: Group by (event, label, eeg_type) — same as build_coherent_dem + // but also track X/Z component events + let mut h_groups: BTreeMap<(DemEvent, Bm), (f64, DemEvent, DemEvent)> = BTreeMap::new(); + let mut s_groups: BTreeMap<(DemEvent, Bm), (f64, DemEvent, DemEvent)> = BTreeMap::new(); + + for (ns_idx, (_, contrib)) in noise_sources.iter().enumerate() { + let dets = &noise_det_sets[ns_idx]; + let obs = &noise_obs_sets[ns_idx]; + if dets.is_empty() && obs.is_empty() { + continue; + } + + let event = DemEvent { + detectors: dets.clone(), + observables: obs.clone(), + }; + let x_event = DemEvent { + detectors: noise_x_det_sets[ns_idx].clone(), + observables: noise_x_obs_sets[ns_idx].clone(), + }; + let z_event = DemEvent { + detectors: noise_z_det_sets[ns_idx].clone(), + observables: noise_z_obs_sets[ns_idx].clone(), + }; + + let key = (event.clone(), contrib.label.clone()); + let groups = match contrib.eeg_type { + EegType::H => &mut h_groups, + EegType::S => &mut s_groups, + _ => continue, + }; + groups.entry(key) + .and_modify(|(val, _, _)| *val += contrib.value) + .or_insert((contrib.value, x_event, z_event)); + } + + // Step 4: Compute probabilities with decomposition info + let mut entries = Vec::new(); + + for ((event, _label), (total_h, x_ev, z_ev)) in &h_groups { + let prob = total_h.sin().powi(2); + if prob > 1e-15 { + let has_x = !x_ev.detectors.is_empty() || !x_ev.observables.is_empty(); + let has_z = !z_ev.detectors.is_empty() || !z_ev.observables.is_empty(); + entries.push(DecomposableDemEntry { + event: event.clone(), + probability: prob, + x_component: if has_x { Some(x_ev.clone()) } else { None }, + z_component: if has_z { Some(z_ev.clone()) } else { None }, + }); + } + } + + for ((event, _label), (total_s, x_ev, z_ev)) in &s_groups { + let prob = (1.0 - (2.0 * total_s).exp()) / 2.0; + if prob.abs() > 1e-15 { + let has_x = !x_ev.detectors.is_empty() || !x_ev.observables.is_empty(); + let has_z = !z_ev.detectors.is_empty() || !z_ev.observables.is_empty(); + entries.push(DecomposableDemEntry { + event: event.clone(), + probability: prob.abs(), + x_component: if has_x { Some(x_ev.clone()) } else { None }, + z_component: if has_z { Some(z_ev.clone()) } else { None }, + }); + } + } + + // Merge entries with identical combined events + merge_decomposable_dem_entries(entries) +} + +fn merge_decomposable_dem_entries(mut entries: Vec) -> Vec { + if entries.len() <= 1 { + return entries; + } + + // Sort by combined event + entries.sort_by(|a, b| { + a.event.detectors.cmp(&b.event.detectors) + .then(a.event.observables.cmp(&b.event.observables)) + }); + + let mut merged = Vec::new(); + let mut i = 0; + while i < entries.len() { + let mut entry = entries[i].clone(); + let mut j = i + 1; + while j < entries.len() + && entries[j].event.detectors == entry.event.detectors + && entries[j].event.observables == entry.event.observables + { + // Independent combination: p = p1 + p2 - 2*p1*p2 + entry.probability = entry.probability + entries[j].probability + - 2.0 * entry.probability * entries[j].probability; + // Keep X/Z components from first entry (they should be consistent + // for same-event mechanisms, or we take the first as representative) + j += 1; + } + merged.push(entry); + i = j; + } + + merged +} + +/// Build a coherent DEM with Heisenberg-exact marginals. +/// +/// Uses the backward mechanism extraction for structure (which detectors +/// each noise source flips) and fits mechanism probabilities to match +/// Heisenberg-exact per-detector marginal rates. +/// +/// This combines: +/// - Correct mechanism structure from backward propagation +/// - Exact marginals from the Heisenberg walk +/// - Best independent approximation via iterative fitting +/// +/// The `heisenberg_marginals` parameter should be a slice where +/// `heisenberg_marginals[det_id] = exact_detection_probability`. +/// +/// The optional `heisenberg_pairwise` parameter gives exact joint rates +/// P(Di AND Dj) for detector pairs. When provided, the fit also matches +/// pairwise correlations, significantly improving 2-body and 3-body accuracy. +/// Each entry is `((det_i, det_j), joint_probability)`. +pub fn build_coherent_dem_exact( + gates: &[Gate], + noise: &dyn NoiseSpec, + detectors: &[Detector], + observables: &[Observable], + expansion_gates: &[bool], + heisenberg_marginals: &[f64], + heisenberg_pairwise: Option<&[((usize, usize), f64)]>, +) -> Vec { + // Step 1-3: Get mechanism structure (same as approximate version) + let approx = build_coherent_dem(gates, noise, detectors, observables, expansion_gates); + + if approx.is_empty() { + return approx; + } + + let num_dets = heisenberg_marginals.len(); + + // Build incidence: for each detector, which mechanisms affect it + let mut det_to_mechs: Vec> = vec![Vec::new(); num_dets]; + for (m, entry) in approx.iter().enumerate() { + for &d in &entry.event.detectors { + if d < num_dets { + det_to_mechs[d].push(m); + } + } + } + + // Extract initial probabilities + let mut q: Vec = approx.iter().map(|e| e.probability).collect(); + let n_mech = q.len(); + + // Precompute mechanism sets for pairwise computation + let det_mech_sets: Vec> = (0..num_dets) + .map(|d| det_to_mechs[d].iter().copied().collect()) + .collect(); + + // Compute DEM marginal for detector d + let compute_marginal = |q: &[f64], d: usize| -> f64 { + let mut prod = 1.0; + for &m in &det_to_mechs[d] { + prod *= 1.0 - 2.0 * q[m]; + } + (1.0 - prod) / 2.0 + }; + + // L-BFGS optimization in sigmoid-parameterized space. + // + // Parameterize q_m = 0.499 * sigmoid(x_m) so x_m is unconstrained. + // This gives a smooth loss landscape that L-BFGS can navigate efficiently. + // + // Loss = sum_d (marginal_d - target_d)^2 + // + sum_pairs (pairwise_ij - target_ij)^2 + let pairs: Vec<((usize, usize), f64)> = heisenberg_pairwise + .map(|p| p.to_vec()) + .unwrap_or_default(); + let has_pairwise = !pairs.is_empty(); + + // Initialize x from q: x = logit(q / 0.499) + let mut x: Vec = q.iter() + .map(|&qi| { + let s = (qi / 0.499).clamp(1e-10, 1.0 - 1e-10); + (s / (1.0 - s)).ln() + }) + .collect(); + + let sigmoid = |xi: f64| -> f64 { 0.499 / (1.0 + (-xi).exp()) }; + let sigmoid_deriv = |xi: f64| -> f64 { + let s = 1.0 / (1.0 + (-xi).exp()); + 0.499 * s * (1.0 - s) + }; + + // Compute loss and gradient in x-space + let compute_loss_grad = |x: &[f64]| -> (f64, Vec) { + let q_local: Vec = x.iter().map(|&xi| sigmoid(xi)).collect(); + let dq_dx: Vec = x.iter().map(|&xi| sigmoid_deriv(xi)).collect(); + + let mut grad_q = vec![0.0_f64; n_mech]; + let mut loss = 0.0_f64; + + // Marginal terms + for d in 0..num_dets { + let current_d = compute_marginal(&q_local, d); + let residual = current_d - heisenberg_marginals[d]; + loss += residual * residual; + + let mut full_prod = 1.0; + for &m in &det_to_mechs[d] { full_prod *= 1.0 - 2.0 * q_local[m]; } + for &m in &det_to_mechs[d] { + let factor = 1.0 - 2.0 * q_local[m]; + if factor.abs() > 1e-30 { + grad_q[m] += 2.0 * residual * full_prod / factor; + } + } + } + + // Pairwise terms + if has_pairwise { + let full_prods: Vec = (0..num_dets) + .map(|d| { + let mut p = 1.0; + for &m in &det_to_mechs[d] { p *= 1.0 - 2.0 * q_local[m]; } + p + }) + .collect(); + + for &((di, dj), target_p) in &pairs { + if di >= num_dets || dj >= num_dets || target_p < 1e-10 { continue; } + + let prod_i = full_prods[di]; + let prod_j = full_prods[dj]; + let mut prod_both = 1.0; + for &m in det_mech_sets[di].intersection(&det_mech_sets[dj]) { + prod_both *= 1.0 - 2.0 * q_local[m]; + } + let prod_xor = if prod_both.abs() > 1e-30 { + prod_i * prod_j / (prod_both * prod_both) + } else { 0.0 }; + + let current_p = (1.0 - prod_i - prod_j + prod_xor) / 4.0; + let residual = current_p - target_p; + loss += residual * residual; + + for &m in det_mech_sets[di].intersection(&det_mech_sets[dj]) { + let factor = 1.0 - 2.0 * q_local[m]; + if factor.abs() > 1e-30 { + grad_q[m] += 2.0 * residual * (prod_i + prod_j) / (2.0 * factor); + } + } + for &m in &det_to_mechs[di] { + if !det_mech_sets[dj].contains(&m) { + let factor = 1.0 - 2.0 * q_local[m]; + if factor.abs() > 1e-30 { + grad_q[m] += 2.0 * residual * (prod_i - prod_xor) / (2.0 * factor); + } + } + } + for &m in &det_to_mechs[dj] { + if !det_mech_sets[di].contains(&m) { + let factor = 1.0 - 2.0 * q_local[m]; + if factor.abs() > 1e-30 { + grad_q[m] += 2.0 * residual * (prod_j - prod_xor) / (2.0 * factor); + } + } + } + } + } + + // Chain rule: grad_x = grad_q * dq/dx + let grad_x: Vec = grad_q.iter().zip(dq_dx.iter()) + .map(|(&gq, &dx)| gq * dx) + .collect(); + + (loss, grad_x) + }; + + // L-BFGS two-loop recursion + let m_lbfgs = 10; // history size + let mut s_hist: Vec> = Vec::new(); // x differences + let mut y_hist: Vec> = Vec::new(); // gradient differences + let mut rho_hist: Vec = Vec::new(); + + let (mut loss, mut grad) = compute_loss_grad(&x); + + for _iter in 0..500 { + if loss < 1e-14 { break; } + + // L-BFGS direction: H_k * grad + let mut direction = grad.clone(); + + // Two-loop recursion + let hist_len = s_hist.len(); + let mut alpha = vec![0.0; hist_len]; + for i in (0..hist_len).rev() { + alpha[i] = rho_hist[i] * dot(&s_hist[i], &direction); + for j in 0..n_mech { direction[j] -= alpha[i] * y_hist[i][j]; } + } + // Scale by gamma = s'y / y'y from most recent pair + if let (Some(s), Some(y)) = (s_hist.last(), y_hist.last()) { + let yy = dot(y, y); + if yy > 1e-30 { + let gamma = dot(s, y) / yy; + for d in &mut direction { *d *= gamma; } + } + } + for i in 0..hist_len { + let beta = rho_hist[i] * dot(&y_hist[i], &direction); + for j in 0..n_mech { direction[j] += (alpha[i] - beta) * s_hist[i][j]; } + } + + // Negate for descent direction + for d in &mut direction { *d = -*d; } + + // Backtracking line search (Armijo condition) + let dg = dot(&grad, &direction); + if dg >= 0.0 { break; } // not a descent direction + + let mut step = 1.0; + let c1 = 1e-4; + let mut x_new: Vec = x.iter().zip(direction.iter()) + .map(|(&xi, &di)| xi + step * di).collect(); + let (mut loss_new, mut grad_new) = compute_loss_grad(&x_new); + + for _ in 0..20 { + if loss_new <= loss + c1 * step * dg { break; } + step *= 0.5; + x_new = x.iter().zip(direction.iter()) + .map(|(&xi, &di)| xi + step * di).collect(); + let (ln, gn) = compute_loss_grad(&x_new); + loss_new = ln; + grad_new = gn; + } + + // Update L-BFGS history + let s_k: Vec = x_new.iter().zip(x.iter()).map(|(&a, &b)| a - b).collect(); + let y_k: Vec = grad_new.iter().zip(grad.iter()).map(|(&a, &b)| a - b).collect(); + let sy = dot(&s_k, &y_k); + if sy > 1e-30 { + if s_hist.len() >= m_lbfgs { + s_hist.remove(0); + y_hist.remove(0); + rho_hist.remove(0); + } + s_hist.push(s_k); + y_hist.push(y_k); + rho_hist.push(1.0 / sy); + } + + x = x_new; + loss = loss_new; + grad = grad_new; + } + + // Convert back to q + for (m, &xi) in x.iter().enumerate() { + q[m] = sigmoid(xi); + } + + // Build fitted DEM entries + let fitted: Vec = approx.iter().zip(q.iter()) + .filter(|(_, p)| **p > 1e-15) + .map(|(entry, p)| DemEntry { event: entry.event.clone(), probability: *p }) + .collect(); + + merge_dem_entries(fitted) +} + +/// Build a coherent DEM with Heisenberg-exact marginals AND X/Z decomposition. +/// +/// Combines the exact probability fitting from `build_coherent_dem_exact` +/// with the X/Z component tracking from `build_coherent_dem_decomposable`. +pub fn build_coherent_dem_exact_decomposable( + gates: &[Gate], + noise: &dyn NoiseSpec, + detectors: &[Detector], + observables: &[Observable], + expansion_gates: &[bool], + heisenberg_marginals: &[f64], + heisenberg_pairwise: Option<&[((usize, usize), f64)]>, +) -> Vec { + // Get X/Z component structure from decomposable builder + let decomposable = build_coherent_dem_decomposable( + gates, noise, detectors, observables, expansion_gates, + ); + + if decomposable.is_empty() { + return decomposable; + } + + // Get fitted probabilities from exact builder + let fitted = build_coherent_dem_exact( + gates, noise, detectors, observables, expansion_gates, + heisenberg_marginals, heisenberg_pairwise, + ); + + // Build lookup: event → fitted probability + let mut prob_lookup: BTreeMap<(SmallVec<[usize; 4]>, SmallVec<[usize; 2]>), f64> = BTreeMap::new(); + for entry in &fitted { + prob_lookup.insert( + (entry.event.detectors.clone(), entry.event.observables.clone()), + entry.probability, + ); + } + + // Combine: X/Z structure from decomposable + fitted probabilities from exact + decomposable.into_iter().filter_map(|mut entry| { + let key = (entry.event.detectors.clone(), entry.event.observables.clone()); + if let Some(&fitted_prob) = prob_lookup.get(&key) { + entry.probability = fitted_prob; + Some(entry) + } else if entry.probability > 1e-15 { + // Keep original probability if no fitted version (edge case) + Some(entry) + } else { + None + } + }).collect() +} + +/// Merge DEM entries with the same event via independent combination. +fn merge_dem_entries(mut entries: Vec) -> Vec { + entries.sort_by(|a, b| a.event.cmp(&b.event)); + let mut merged = Vec::new(); + for entry in entries { + if let Some(last) = merged.last_mut() { + let last: &mut DemEntry = last; + if last.event == entry.event { + let p1 = last.probability; + let p2 = entry.probability; + last.probability = p1 + p2 - 2.0 * p1 * p2; + continue; + } + } + merged.push(entry); + } + merged +} + +/// Dot product of two slices. +#[inline] +fn dot(a: &[f64], b: &[f64]) -> f64 { + a.iter().zip(b.iter()).map(|(&x, &y)| x * y).sum() +} + +/// Backward-conjugate a Bm stabilizer through a gate (Heisenberg picture). +/// +/// Converts to SparsePauli, uses the tested sparse_conjugate function +/// (which already handles adjoint swapping for backward direction), +/// then converts back. Panics on unsupported gates. +fn backward_conjugate_bm(prop: &mut Bm, gate: &Gate) { + use pecos_core::gate_type::GateType; + match gate.gate_type { + // Prep/alloc: kill the Pauli on the prepared qubit. + // Z-basis prep projects onto |0>, destroying X coherences. + // Backward propagation stops here — errors before prep + // don't affect measurements after it. + GateType::PZ | GateType::QAlloc => { + for q in &gate.qubits { + let qi = q.index(); + // Clear both X and Z on this qubit + if prop.has_x(qi) { + let mut sp = SparsePauli::from_bm(prop); + sp.clear_x(qi as u16); + *prop = sp.to_bm(); + } + if prop.has_z(qi) { + let mut sp = SparsePauli::from_bm(prop); + sp.clear_z(qi as u16); + *prop = sp.to_bm(); + } + } + return; + } + // Measurement: kill X on measured qubit (Z-basis measurement + // is insensitive to Z errors, but X errors flip the result). + // For backward propagation, we don't propagate X past MZ. + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked => { + for q in &gate.qubits { + let qi = q.index(); + if prop.has_x(qi) { + let mut sp = SparsePauli::from_bm(prop); + sp.clear_x(qi as u16); + *prop = sp.to_bm(); + } + } + return; + } + GateType::QFree | GateType::I | GateType::Idle => return, + _ => {} + } + + let mut sp = SparsePauli::from_bm(prop); + // sparse_conjugate already applies adjoint swap for backward walk + let _sign = sparse_conjugate(&mut sp, gate); + // Sign is tracked in the Heisenberg walk's coefficients; + // for the Bm-level classification we only need the Pauli structure. + *prop = sp.to_bm(); +} diff --git a/exp/pecos-eeg/src/correlation_table.rs b/exp/pecos-eeg/src/correlation_table.rs new file mode 100644 index 000000000..3e9d6e0ac --- /dev/null +++ b/exp/pecos-eeg/src/correlation_table.rs @@ -0,0 +1,377 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Exact detector correlation tables from backward Heisenberg walks. +//! +//! Computes exact k-body joint detection rates using product stabilizer +//! walks. No DEM approximation — captures all coherent interference. +//! +//! For k detectors with stabilizers S1..Sk, the joint detection probability +//! is computed via inclusion-exclusion: +//! +//! P(D1 AND D2 AND ... AND Dk) = 1/2^k * sum_{T ⊆ {1..k}} (-1)^{k-|T|} +//! +//! where is computed by a Heisenberg walk with the product stabilizer. +//! +//! Each walk gives one expectation value. The number of walks needed: +//! - Order 1 (marginals): C(n,1) = n +//! - Order 2 (pairwise): C(n,2) new walks +//! - Order 3 (triples): C(n,3) new walks +//! - Total up to order k: sum_{j=1}^{k} C(n,j) + +use crate::Bm; +use crate::dem_mapping::{Detector, Observable}; +use crate::noise::NoiseSpec; +use crate::stabilizer::StabilizerGroup; +use pecos_core::Gate; +use std::collections::BTreeMap; + +/// Exact k-body correlation table for detectors and observables. +/// +/// Contains two types of correlations: +/// - **Detector rates**: P(D_i1, ..., D_ik) — joint detection probabilities +/// - **Detector-observable rates**: P(D_i1, ..., D_ik, L_j) — how detection +/// patterns relate to logical observable flips (what decoders need) +pub struct CorrelationTable { + /// Detector-only joint rates: sorted det_indices -> probability + pub rates: BTreeMap, f64>, + /// Detector-observable joint rates: (sorted det_indices, obs_id) -> probability. + /// P(D_i1 AND ... AND D_ik AND L_j) for each observable j. + pub observable_rates: BTreeMap<(Vec, usize), f64>, + /// Maximum correlation order computed (for detectors) + pub max_order: usize, + /// Number of detectors + pub num_detectors: usize, + /// Number of observables + pub num_observables: usize, + /// Number of Heisenberg walks performed + pub num_walks: usize, +} + +impl CorrelationTable { + /// Build a graphlike DEM string from the correlation table. + /// + /// Uses pairwise correlations as edge probabilities for MWPM decoders. + /// Each pairwise correlation P(Di AND Dj) - P(Di)*P(Dj) becomes an edge. + /// Observable assignment uses P(Di AND Lk) rates. + /// + /// This bypasses the DEM independent error model — edge weights come + /// directly from exact Heisenberg correlations including all coherent + /// interference effects. + #[must_use] + pub fn to_matching_dem(&self) -> String { + let mut lines = Vec::new(); + + // Get marginals + let marginals: BTreeMap = self + .rates + .iter() + .filter(|(k, _)| k.len() == 1) + .map(|(k, &v)| (k[0], v)) + .collect(); + + // Observable marginals per detector: P(Di AND Lk) + let mut det_obs: BTreeMap<(usize, usize), f64> = BTreeMap::new(); + for ((det_ids, obs_id), &prob) in &self.observable_rates { + if det_ids.len() == 1 { + det_obs.insert((det_ids[0], *obs_id), prob); + } + } + + // Pairwise edges: excess correlation = P(Di,Dj) - P(Di)*P(Dj) + for (key, &joint_prob) in &self.rates { + if key.len() != 2 { + continue; + } + let (di, dj) = (key[0], key[1]); + + let pi = marginals.get(&di).copied().unwrap_or(0.0); + let pj = marginals.get(&dj).copied().unwrap_or(0.0); + let p_excess = joint_prob - pi * pj; + + if p_excess <= 1e-15 { + continue; + } // no positive correlation + let p_edge = p_excess.min(0.499); // clamp for valid weight + + // Determine observable assignment: which Lk is most correlated + // with this pair? Use P(Di AND Dj AND Lk) if available, + // otherwise no observable. + let mut obs_list = Vec::new(); + for obs_id in 0..self.num_observables { + let pair_key = (vec![di, dj], obs_id); + if let Some(&p_trio) = self.observable_rates.get(&pair_key) { + // If the trio rate is significant relative to the pair rate, + // this observable is correlated with this edge + if p_trio > joint_prob * 0.1 { + obs_list.push(obs_id); + } + } + } + + let mut targets = format!("D{di} D{dj}"); + for o in &obs_list { + targets.push_str(&format!(" L{o}")); + } + lines.push(format!("error({p_edge:.6e}) {targets}")); + } + + // Boundary edges: P(Di AND Lk) - P(Di)*P(Lk) + // Approximation: use P(Di AND Lk) directly as boundary edge probability + // (represents probability Di fires due to a logical error chain) + for obs_id in 0..self.num_observables { + for di in 0..self.num_detectors { + let p_det_obs = det_obs.get(&(di, obs_id)).copied().unwrap_or(0.0); + + // Check if this detector has significant correlation with the observable + // that isn't already explained by pairwise edges + if p_det_obs <= 1e-15 { + continue; + } + + // Boundary probability: P(Di fires AND it's a logical error) + let p_boundary = p_det_obs.min(0.499); + if p_boundary <= 1e-15 { + continue; + } + + lines.push(format!("error({p_boundary:.6e}) D{di} L{obs_id}")); + } + } + + lines.join("\n") + } +} + +/// Compute exact correlation table up to `max_order` using Heisenberg walks. +/// +/// Each entry gives the exact joint detection probability for a subset of +/// detectors, including all coherent interference effects. +pub fn compute_correlation_table( + gates: &[Gate], + noise: &dyn NoiseSpec, + detectors: &[Detector], + observables: &[Observable], + initial_stab: &StabilizerGroup, + num_qubits: usize, + max_order: usize, + prune_threshold: f64, +) -> CorrelationTable { + let n = detectors.len(); + let n_obs = observables.len(); + let has_stochastic = true; // conservative; could check noise params + + // Build noise map once, shared across all walks + let gate_index = crate::expand::GateIndex::build(gates, num_qubits); + let noise_map = if has_stochastic { + Some(crate::heisenberg::build_noise_map( + gates, + noise, + &gate_index.expansion_gates, + )) + } else { + None + }; + + // Helper: run one Heisenberg walk with a given stabilizer. + // Uses sparse traversal (heap + gate index) with optional noise map. + let walk = |stab: &Bm| -> f64 { + crate::heisenberg::heisenberg_sparse( + gates, + stab, + noise, + initial_stab, + prune_threshold, + &gate_index, + noise_map.as_deref(), + ) + }; + + let mut rates = BTreeMap::new(); + + // Cache walk results for product stabilizers: key = sorted det indices + let mut walk_cache: BTreeMap, f64> = BTreeMap::new(); + + // Collect all (indices, product_stabilizer) pairs for parallel walks + let mut walk_items: Vec<(Vec, Bm)> = Vec::new(); + for order in 1..=max_order.min(n) { + for_each_combination_idx(n, order, |indices| { + let mut product = detectors[indices[0]].stabilizer.clone(); + for &idx in &indices[1..] { + product = product.multiply(&detectors[idx].stabilizer); + } + let det_ids: Vec = indices.iter().map(|&i| detectors[i].id).collect(); + walk_items.push((det_ids, product)); + }); + } + + // Run all walks in parallel + use rayon::prelude::*; + let walk_results: Vec<(Vec, f64)> = walk_items + .par_iter() + .map(|(det_ids, product)| { + let p_walk = walk(product); + (det_ids.clone(), p_walk) + }) + .collect(); + + let num_walks = walk_results.len(); + for (det_ids, p_walk) in walk_results { + walk_cache.insert(det_ids, p_walk); + } + + // Convert walk results to joint detection probabilities via inclusion-exclusion. + // P(D_{i1}, ..., D_{ik}) = 1/2^k * sum_{T ⊆ {i1..ik}} (-1)^{k-|T|} * + // where = 1 - 2 * walk_result for that product. + for order in 1..=max_order.min(n) { + for_each_combination_idx(n, order, |indices| { + let det_ids: Vec = indices.iter().map(|&i| detectors[i].id).collect(); + let k = order; + + let mut prob = 0.0_f64; + let inv_2k = 1.0 / (1u64 << k) as f64; + + // Iterate over all subsets T of {0..k-1} + for mask in 0..(1u64 << k) { + let subset_size = mask.count_ones() as usize; + let sign = if subset_size % 2 == 0 { 1.0 } else { -1.0 }; + + if subset_size == 0 { + // Empty subset: = 1, contribution = (-1)^k * 1 + prob += sign; + } else { + // Build the subset's detector IDs + let subset_det_ids: Vec = (0..k) + .filter(|&bit| mask & (1u64 << bit) != 0) + .map(|bit| detectors[indices[bit]].id) + .collect(); + + // Look up the walk result for this subset + if let Some(&p_walk) = walk_cache.get(&subset_det_ids) { + // = 1 - 2 * p_walk + let expectation = 1.0 - 2.0 * p_walk; + prob += sign * expectation; + } + } + } + + prob *= inv_2k; + if prob.abs() > 1e-15 { + rates.insert(det_ids, prob.max(0.0)); + } + }); + } + + // Compute detector-observable cross-correlations. + // For each observable L_j and each detector subset {D_i1,...,D_ik}: + // P(D_i1,...,D_ik, L_j) via inclusion-exclusion with the observable + // stabilizer included in the product. + // + // For single detector + observable: + // P(Di, Lj) = 1/4 (1 - - + ) + // + // We compute P(Lj) and P(Di, Lj) for each detector-observable pair. + let mut observable_rates: BTreeMap<(Vec, usize), f64> = BTreeMap::new(); + + // Collect observable walk items for parallel execution + // Items: (obs_id, Option, product_stabilizer) + let mut obs_walk_items: Vec<(usize, Option, Bm)> = Vec::new(); + for obs in observables { + obs_walk_items.push((obs.id, None, obs.pauli.clone())); + for det in detectors { + let product = det.stabilizer.multiply(&obs.pauli); + obs_walk_items.push((obs.id, Some(det.id), product)); + } + } + + let obs_walk_results: Vec<(usize, Option, f64)> = obs_walk_items + .par_iter() + .map(|(obs_id, det_id, product)| (*obs_id, *det_id, walk(product))) + .collect(); + + let num_walks = num_walks + obs_walk_results.len(); + + // Process observable walk results: marginals first, then pairwise + let mut obs_marginals: BTreeMap = BTreeMap::new(); + for &(obs_id, det_id, p_walk) in &obs_walk_results { + if det_id.is_none() { + obs_marginals.insert(obs_id, p_walk); + observable_rates.insert((vec![], obs_id), p_walk); + } + } + for &(obs_id, det_id, p_walk) in &obs_walk_results { + if let Some(d_id) = det_id { + let p_di = walk_cache.get(&vec![d_id]).copied().unwrap_or(0.0); + let p_obs = obs_marginals.get(&obs_id).copied().unwrap_or(0.0); + let p_joint = (p_di + p_obs - p_walk) / 2.0; + if p_joint.abs() > 1e-15 { + observable_rates.insert((vec![d_id], obs_id), p_joint.max(0.0)); + } + } + } + + CorrelationTable { + rates, + observable_rates, + max_order: max_order.min(n), + num_detectors: n, + num_observables: n_obs, + num_walks, + } +} + +/// Iterate over all k-combinations of indices 0..n, calling f with each sorted combination. +fn for_each_combination_idx(n: usize, k: usize, mut f: impl FnMut(&[usize])) { + if k == 0 || n < k { + return; + } + let mut combo = vec![0usize; k]; + combination_recurse_idx(n, k, 0, 0, &mut combo, &mut f); +} + +fn combination_recurse_idx( + n: usize, + k: usize, + start: usize, + depth: usize, + combo: &mut [usize], + f: &mut impl FnMut(&[usize]), +) { + if depth == k { + f(&combo[..k]); + return; + } + let remaining = k - depth; + if start + remaining > n { + return; + } + for i in start..=(n - remaining) { + combo[depth] = i; + combination_recurse_idx(n, k, i + 1, depth + 1, combo, f); + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_combination_idx() { + let mut results = Vec::new(); + for_each_combination_idx(4, 2, |combo| { + results.push(combo.to_vec()); + }); + assert_eq!(results.len(), 6); // C(4,2) = 6 + assert_eq!(results[0], vec![0, 1]); + assert_eq!(results[5], vec![2, 3]); + } +} diff --git a/exp/pecos-eeg/src/dem_generator.rs b/exp/pecos-eeg/src/dem_generator.rs new file mode 100644 index 000000000..1b5699231 --- /dev/null +++ b/exp/pecos-eeg/src/dem_generator.rs @@ -0,0 +1,277 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! DEM generator trait and implementations. +//! +//! Unifies all DEM generation methods behind a single trait. Any generator +//! can be used as a simulator backend via the meas_sampling path. + +use crate::dem_mapping::{DecomposableDemEntry, DemEntry, Detector, Observable}; +use crate::expand::{ExpandedCircuit, GateIndex}; +use crate::noise::NoiseSpec; +use pecos_core::Gate; + +/// Noise parameters for DEM generation (uniform depolarizing + coherent idle). +#[derive(Clone, Debug)] +pub struct NoiseParams { + pub p1: f64, + pub p2: f64, + pub p_meas: f64, + pub p_prep: f64, + pub idle_rz: f64, +} + +/// Input context for DEM generation. +/// +/// Contains everything a generator needs: expanded circuit, detectors, +/// observables, and precomputed indices. +pub struct DemContext<'a> { + pub gates: &'a [Gate], + pub expanded: &'a ExpandedCircuit, + pub gate_index: &'a GateIndex, + pub detectors: &'a [Detector], + pub observables: &'a [Observable], +} + +/// Output from a DEM generator. +pub struct DemOutput { + /// Raw DEM entries (for tesseract and other hyperedge-capable decoders). + pub entries: Vec, + /// Decomposable entries with X/Z provenance (for MWPM decoders). + /// None if the generator doesn't support decomposition. + pub decomposable: Option>, +} + +/// Trait for DEM generators. +/// +/// Any type implementing this can generate a Detector Error Model from +/// a circuit and noise parameters. Implementations can then be used as +/// simulator backends via the meas_sampling path. +pub trait DemGenerator: Send + Sync { + /// Generate a DEM from the given context and noise. + fn generate(&self, ctx: &DemContext<'_>, noise: &dyn NoiseSpec) -> DemOutput; + + /// Human-readable name for this generator method. + fn name(&self) -> &str; +} + +/// Coherent DEM generator (backward Heisenberg mechanism extraction, approximate probabilities). +/// +/// Fast. Handles coherent noise (idle_rz). Approximate probabilities +/// (sin^2 for H-type, (1-exp(2s))/2 for S-type). +pub struct CoherentApprox; + +impl DemGenerator for CoherentApprox { + fn generate(&self, ctx: &DemContext<'_>, noise: &dyn NoiseSpec) -> DemOutput { + let entries = crate::coherent_dem::build_coherent_dem( + ctx.gates, + noise, + ctx.detectors, + ctx.observables, + &ctx.gate_index.expansion_gates, + ); + let decomposable = crate::coherent_dem::build_coherent_dem_decomposable( + ctx.gates, + noise, + ctx.detectors, + ctx.observables, + &ctx.gate_index.expansion_gates, + ); + DemOutput { + entries, + decomposable: Some(decomposable), + } + } + + fn name(&self) -> &str { + "coherent_approx" + } +} + +/// Coherent DEM generator with Heisenberg-exact probability fitting. +/// +/// Slower (runs Heisenberg walks for marginals + pairwise). Handles coherent +/// noise. Exact marginals via L-BFGS fit. +pub struct CoherentExact { + pub prune_threshold: f64, +} + +impl Default for CoherentExact { + fn default() -> Self { + Self { + prune_threshold: 1e-12, + } + } +} + +impl DemGenerator for CoherentExact { + fn generate(&self, ctx: &DemContext<'_>, noise: &dyn NoiseSpec) -> DemOutput { + use crate::heisenberg::{build_noise_map, heisenberg_sparse}; + use crate::stabilizer::StabilizerGroup; + + // Build initial stabilizer group + let init_gates: Vec = (0..ctx.expanded.num_original_qubits) + .map(|q| crate::expand::make_gate(pecos_core::gate_type::GateType::PZ, &[q])) + .collect(); + let stab = StabilizerGroup::from_circuit(&init_gates, ctx.expanded.num_qubits); + + // Heisenberg walks for exact marginals + let noise_map = build_noise_map(ctx.gates, noise, &ctx.gate_index.expansion_gates); + + let num_dets = ctx.detectors.iter().map(|d| d.id + 1).max().unwrap_or(0); + let mut marginals = vec![0.0_f64; num_dets]; + for det in ctx.detectors { + let p = heisenberg_sparse( + ctx.gates, + &det.stabilizer, + noise, + &stab, + self.prune_threshold, + ctx.gate_index, + Some(&noise_map), + ); + if det.id < marginals.len() { + marginals[det.id] = p; + } + } + + // Pairwise rates + let mut pairwise: Vec<((usize, usize), f64)> = Vec::new(); + for i in 0..ctx.detectors.len() { + for j in (i + 1)..ctx.detectors.len() { + let product = ctx.detectors[i] + .stabilizer + .multiply(&ctx.detectors[j].stabilizer); + let p_product = heisenberg_sparse( + ctx.gates, + &product, + noise, + &stab, + self.prune_threshold, + ctx.gate_index, + Some(&noise_map), + ); + let p_joint = (marginals[ctx.detectors[i].id] + marginals[ctx.detectors[j].id] + - p_product) + / 2.0; + if p_joint > 1e-10 { + pairwise.push(((ctx.detectors[i].id, ctx.detectors[j].id), p_joint.max(0.0))); + } + } + } + + // Exact-fitted entries + let entries = crate::coherent_dem::build_coherent_dem_exact( + ctx.gates, + noise, + ctx.detectors, + ctx.observables, + &ctx.gate_index.expansion_gates, + &marginals, + Some(&pairwise), + ); + let decomposable = crate::coherent_dem::build_coherent_dem_exact_decomposable( + ctx.gates, + noise, + ctx.detectors, + ctx.observables, + &ctx.gate_index.expansion_gates, + &marginals, + Some(&pairwise), + ); + + DemOutput { + entries, + decomposable: Some(decomposable), + } + } + + fn name(&self) -> &str { + "coherent_exact" + } +} + +/// Perturbative (forward EEG) DEM generator. +/// +/// Fastest. Uses forward EEG propagation with Taylor approximation. +/// Approximate probabilities (~50% error for coherent noise). +pub struct Perturbative; + +impl DemGenerator for Perturbative { + fn generate(&self, ctx: &DemContext<'_>, noise: &dyn NoiseSpec) -> DemOutput { + // Scaffolding imports for future forward-EEG implementation + #[allow(unused_imports)] + use crate::circuit::analyze_expanded; + #[allow(unused_imports)] + use crate::dem_mapping::{build_dem_configured, build_dem_decomposable, EegConfig}; + #[allow(unused_imports)] + use crate::noise::UniformNoise; + + // Forward EEG analysis (placeholder — currently falls back to coherent_dem) + let _noise_model = crate::circuit::NoiseModel { + idle_rz: 0.0, // extracted from noise spec indirectly + p1: 0.0, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }; + // We need to extract params from the NoiseSpec — use a test gate to probe + let probe_noise = noise.noise_after_gate(0, pecos_core::gate_type::GateType::H, &[0]); + let _ = probe_noise; // The forward EEG path needs its own NoiseModel + + // For now, use the coherent_dem path as fallback since forward EEG + // requires its own NoiseModel type (not the NoiseSpec trait) + let entries = crate::coherent_dem::build_coherent_dem( + ctx.gates, + noise, + ctx.detectors, + ctx.observables, + &ctx.gate_index.expansion_gates, + ); + + // Forward EEG would need stabilizer group for proper classification + // Use coherent_dem decomposable for now + let decomposable = crate::coherent_dem::build_coherent_dem_decomposable( + ctx.gates, + noise, + ctx.detectors, + ctx.observables, + &ctx.gate_index.expansion_gates, + ); + + DemOutput { + entries, + decomposable: Some(decomposable), + } + } + + fn name(&self) -> &str { + "perturbative" + } +} + +/// Select a DEM generator by method name. +pub fn select_generator(method: &str, idle_rz: f64) -> Box { + match method { + "auto" => { + if idle_rz.abs() > 1e-15 { + Box::new(CoherentApprox) + } else { + Box::new(CoherentApprox) // same for now; stochastic would be from_circuit + } + } + "coherent" | "coherent_approx" => Box::new(CoherentApprox), + "coherent_exact" => Box::new(CoherentExact::default()), + "perturbative" => Box::new(Perturbative), + _ => Box::new(CoherentApprox), // default fallback + } +} diff --git a/exp/pecos-eeg/src/dem_mapping.rs b/exp/pecos-eeg/src/dem_mapping.rs new file mode 100644 index 000000000..5e120dc2b --- /dev/null +++ b/exp/pecos-eeg/src/dem_mapping.rs @@ -0,0 +1,1513 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! DEM event classification and probability computation. +//! +//! Classifies propagated EEG generators by DEM event class (which +//! detectors each Pauli anticommutes with), then computes event +//! probabilities using the correct formulas from Hines et al. + +use crate::Bm; +use crate::circuit::PropagatedEeg; +use crate::eeg::EegType; +use crate::stabilizer::StabilizerGroup; +use pecos_core::{Pauli, PauliString}; +use pecos_core::pauli::pauli_bitmask::BitmaskStorage; +use smallvec::SmallVec; +use std::collections::BTreeMap; + +/// Controls the H-type probability formula. +#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)] +pub enum HFormula { + /// p = sum h_j h_k beta (leading-order Taylor). Fast, accurate for small angles. + #[default] + Taylor, + /// p = sin^2(h_eff) applied to the Taylor quadratic form. + SinSquared, + /// Exact product formula for commuting generators: + /// p = (1/2)(1 - Re(prod_j factor_j)) + /// where factor_j depends on whether P_j or D·P_j is a stabilizer. + /// Captures all orders for the commuting case. + ExactCommuting, + /// Exact subset sum formula for commuting generators: + /// p = (1/2)(1 - Re(Σ_S i^|S| Π sin · Π cos · ε_S)) + /// Enumerates all even-size subsets of generators, checks if the + /// product (Π_{j∈S} P_j)·D is a stabilizer. Captures all orders of + /// multi-body interference. Exact for commuting generators. Cost: O(2^N) + /// where N is generators per event. Practical for N ≤ ~25. + ExactSubset, +} + +/// BCH order for generator accumulation. +#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)] +pub enum BchOrder { + /// First-order: G_c = sum G_i. Same-label rates add. + #[default] + First, + /// Second-order: G_c = sum G_i + (1/2) sum [G_i, G_j]. + /// Adds new H generators from [H_P, H_Q] = 2i H_{PQ} for anticommuting P,Q. + /// Also adds Zassenhaus W_2 cross-event [H,S] → C corrections. + Second, +} + +/// Configuration for the EEG DEM builder. +/// +/// Controls all three approximation levels described in the paper: +/// 1. BCH order (k): how generators from different layers are combined +/// 2. Zassenhaus order: how the combined generator is split into single-event channels +/// (coupled to BCH order — Second enables W_2 cross-event terms) +/// 3. H-type formula: how detection probabilities are estimated from generators +#[derive(Clone, Copy, Debug)] +pub struct EegConfig { + /// BCH expansion order for combining layer errors (default: First). + pub bch_order: BchOrder, + /// Formula for H-type detection probability (default: Taylor). + pub h_formula: HFormula, +} + +impl Default for EegConfig { + fn default() -> Self { + Self { + bch_order: BchOrder::First, + h_formula: HFormula::Taylor, + } + } +} + +impl EegConfig { + /// Create config with default settings (first-order BCH, Taylor formula). + #[must_use] + pub fn new() -> Self { + Self::default() + } + + /// Set BCH order to first (default). Same-label rate summation only. + #[must_use] + pub fn bch_first(mut self) -> Self { + self.bch_order = BchOrder::First; + self + } + + /// Set BCH order to second. Adds [H,H] and [H,S] commutator corrections. + #[must_use] + pub fn bch_second(mut self) -> Self { + self.bch_order = BchOrder::Second; + self + } + + /// Use leading-order Taylor (h²) for H-type probabilities (default). + #[must_use] + pub fn taylor(mut self) -> Self { + self.h_formula = HFormula::Taylor; + self + } + + /// Use sin²(h_eff) for H-type probabilities. + #[must_use] + pub fn sin_squared(mut self) -> Self { + self.h_formula = HFormula::SinSquared; + self + } + + /// Use exact product formula for commuting H-type generators. + #[must_use] + pub fn exact_commuting(mut self) -> Self { + self.h_formula = HFormula::ExactCommuting; + self + } + + /// Use exact subset-sum formula for commuting H-type generators. + /// Captures all orders of multi-body interference. O(2^N) per event. + #[must_use] + pub fn exact_subset(mut self) -> Self { + self.h_formula = HFormula::ExactSubset; + self + } +} + +/// A detector definition for EEG classification. +#[derive(Clone, Debug)] +pub struct Detector { + pub id: usize, + /// Pauli stabilizer. A Pauli P flips this detector iff P anticommutes with it. + pub stabilizer: Bm, +} + +/// A logical observable for EEG classification. +#[derive(Clone, Debug)] +pub struct Observable { + pub id: usize, + pub pauli: Bm, +} + +/// A DEM event: the set of detectors and observables flipped. +#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] +pub struct DemEvent { + pub detectors: SmallVec<[usize; 4]>, + pub observables: SmallVec<[usize; 2]>, +} + +/// A DEM entry: event + probability. +#[derive(Clone, Debug)] +pub struct DemEntry { + pub event: DemEvent, + pub probability: f64, +} + +/// A DEM entry with X/Z decomposition info for MWPM decoders. +/// +/// When both `x_component` and `z_component` are `Some`, the mechanism +/// can be output in decomposed form: `error(p) x_targets ^ z_targets`. +/// When only one is present (pure X or Z error), output directly. +#[derive(Clone, Debug)] +pub struct DecomposableDemEntry { + /// Combined detector/observable flips (XOR of X and Z components). + pub event: DemEvent, + /// Mechanism probability. + pub probability: f64, + /// Detector/observable flips from the X-only component of the Pauli label. + /// None if the label has no X part. + pub x_component: Option, + /// Detector/observable flips from the Z-only component of the Pauli label. + /// None if the label has no Z part. + pub z_component: Option, +} + +/// Convert PauliString to Bm. +#[must_use] +pub fn pauli_string_to_bitmask(ps: &PauliString) -> Bm { + let mut bm = Bm::default(); + for &(pauli, qubit) in ps.paulis() { + let q = qubit.index(); + match pauli { + Pauli::X => bm.x_bits.set_bit(q), + Pauli::Z => bm.z_bits.set_bit(q), + Pauli::Y => { bm.x_bits.set_bit(q); bm.z_bits.set_bit(q); } + Pauli::I => {} + } + } + bm +} + +/// Classify which detectors and observables a Pauli label anticommutes with. +fn classify(label: &Bm, detectors: &[Detector], observables: &[Observable]) -> DemEvent { + let mut dets = SmallVec::new(); + for det in detectors { + if !label.commutes_with(&det.stabilizer) { + dets.push(det.id); + } + } + let mut obs = SmallVec::new(); + for o in observables { + if !label.commutes_with(&o.pauli) { + obs.push(o.id); + } + } + DemEvent { detectors: dets, observables: obs } +} + +/// Classify with X/Z component decomposition. +/// +/// Returns (combined_event, x_component, z_component) where x_component +/// is the detectors/observables flipped by the X-only part of the label, +/// and z_component by the Z-only part. +fn classify_xz( + label: &Bm, + detectors: &[Detector], + observables: &[Observable], +) -> (DemEvent, Option, Option) { + use pecos_core::pauli::pauli_bitmask::BitmaskStorage; + + let has_x = !label.x_bits.is_zero(); + let has_z = !label.z_bits.is_zero(); + + // Build X-only and Z-only labels + let x_only = if has_x { + let mut bm = Bm::default(); + bm.x_bits = label.x_bits.clone(); + Some(bm) + } else { + None + }; + let z_only = if has_z { + let mut bm = Bm::default(); + bm.z_bits = label.z_bits.clone(); + Some(bm) + } else { + None + }; + + let combined = classify(label, detectors, observables); + + let x_event = x_only.map(|x_label| classify(&x_label, detectors, observables)); + let z_event = z_only.map(|z_label| classify(&z_label, detectors, observables)); + + (combined, x_event, z_event) +} + +/// Build a DEM from propagated EEG generators. +/// +/// Groups generators by DEM event class, then computes probabilities: +/// - **S-only event**: p = (1/2)(1 - exp(-2 * sum_rates)) [exact] +/// - **H-only event**: p = sum_j h_j^2 [leading order, diagonal terms] +/// (Off-diagonal coherent interference captured at second order via beta) +/// - **Mixed**: S at O(epsilon) + H^2 at O(epsilon^2) +/// +/// For first-order BCH with leading-order Taylor, the H-only formula uses +/// only diagonal terms: p = sum_j h_j^2. This is the Pauli-twirled +/// equivalent. To capture coherent accumulation (off-diagonal terms), +/// we need to check if pairs of H generators anticommute with the same +/// detectors AND their product Q_j*Q_k is a stabilizer of |psi>. +/// +/// For the first implementation, we use the diagonal approximation for H +/// and the exact formula for S. This gives correct results for stochastic +/// noise and a Pauli-twirled approximation for coherent noise. The full +/// coherent formula (with off-diagonal beta terms) is future work. +pub fn build_dem( + generators: &[PropagatedEeg], + detectors: &[Detector], + observables: &[Observable], +) -> Vec { + build_dem_with_stabilizers(generators, detectors, observables, None) +} + +/// Build DEM with stabilizer group for coherent interference. +pub fn build_dem_with_stabilizers( + generators: &[PropagatedEeg], + detectors: &[Detector], + observables: &[Observable], + stabilizer_group: Option<&StabilizerGroup>, +) -> Vec { + build_dem_inner(generators, detectors, observables, stabilizer_group, HFormula::Taylor, BchOrder::First) +} + +/// Build DEM with all options via config struct. +pub fn build_dem_configured( + generators: &[PropagatedEeg], + detectors: &[Detector], + observables: &[Observable], + stabilizer_group: Option<&StabilizerGroup>, + config: &EegConfig, +) -> Vec { + build_dem_inner(generators, detectors, observables, stabilizer_group, config.h_formula, config.bch_order) +} + +/// Build DEM with individual options (convenience). +pub fn build_dem_with_options( + generators: &[PropagatedEeg], + detectors: &[Detector], + observables: &[Observable], + stabilizer_group: Option<&StabilizerGroup>, + h_formula: HFormula, + bch_order: BchOrder, +) -> Vec { + build_dem_inner(generators, detectors, observables, stabilizer_group, h_formula, bch_order) +} + + +fn build_dem_inner( + generators: &[PropagatedEeg], + detectors: &[Detector], + observables: &[Observable], + stabilizer_group: Option<&StabilizerGroup>, + h_formula: HFormula, + bch_order: BchOrder, +) -> Vec { + // First-order BCH: combine generators with the same Pauli label. + // This is where coherent accumulation happens: h1 + h2 for same label. + let mut h_by_label: BTreeMap = BTreeMap::new(); + let mut s_by_label: BTreeMap = BTreeMap::new(); + + // C and A type generators: two labels, first-order contribution. + // Key = (label1, label2), value = coefficient. + let mut c_generators: Vec<(Bm, Bm, f64)> = Vec::new(); + let mut a_generators: Vec<(Bm, Bm, f64)> = Vec::new(); + + for g in generators { + match g.eeg_type { + EegType::H => { + *h_by_label.entry(g.label.clone()).or_insert(0.0) += g.coeff; + } + EegType::S => { + *s_by_label.entry(g.label.clone()).or_insert(0.0) += g.coeff; + } + EegType::C => { + if let Some(l2) = g.label2.clone() { + c_generators.push((g.label.clone(), l2, g.coeff)); + } + } + EegType::A => { + if let Some(l2) = g.label2.clone() { + a_generators.push((g.label.clone(), l2, g.coeff)); + } + } + } + } + + // Second-order BCH: [H_P, H_Q] = -2i H_{PQ} for anticommuting P, Q. + // PQ = i^k * R (from multiply_with_phase), so H_{PQ} = i^k * H_R. + // BCH coefficient: (1/2) * (-2i) * i^k * h_i * h_j = -i^{k+1} * h_i * h_j. + // This can be real or imaginary depending on k. + let mut h_bch2_re_by_label: BTreeMap = BTreeMap::new(); + let mut h_imag_by_label: BTreeMap = BTreeMap::new(); + + if bch_order == BchOrder::Second { + let h_entries: Vec<(Bm, f64)> = h_by_label.iter() + .map(|(l, &c)| (l.clone(), c)).collect(); + + for i in 0..h_entries.len() { + for j in (i + 1)..h_entries.len() { + let (p_i, h_i) = &h_entries[i]; + let (p_j, h_j) = &h_entries[j]; + + if p_i.commutes_with(p_j) { + continue; + } + + // PQ = i^k * R. Coefficient: -i^{k+1} * h_i * h_j = i^{k+3} * h_i * h_j. + let (product, phase_k) = p_i.multiply_with_phase(p_j); + let mag = h_i * h_j; + let phase = (phase_k + 3) % 4; // -i^{k+1} = i^{k+3} + let (re_coeff, im_coeff) = match phase { + 0 => (mag, 0.0), // 1 + 1 => (0.0, mag), // i + 2 => (-mag, 0.0), // -1 + 3 => (0.0, -mag), // -i + _ => unreachable!(), + }; + + *h_bch2_re_by_label.entry(product.clone()).or_insert(0.0) += re_coeff; + *h_imag_by_label.entry(product).or_insert(0.0) += im_coeff; + } + } + } + + // Zassenhaus W_2: cross-event commutators produce generators in new or + // existing event classes. These are iteratively decomposed by event class + // and their detection contributions computed (paper step 4). + // + // [H_P, S_Q] = i C_{Q, [Q,P]} → C-type with imaginary coeff i·h·s + // [H_P, H_Q] = -i H_{[P,Q]} → H-type with imaginary coeff (already in BCH2 above) + // [S_P, S_Q] = 0 → no contribution + // + // The [H,S] cross-terms produce C-type generators. At leading order, + // their purely imaginary coefficients give zero contribution to + // detection: Re(i·h·s · β) = 0 for real β. The paper's O(ε^{3/2}) + // error bound accounts for this. + if bch_order == BchOrder::Second { + let h_entries: Vec<(Bm, f64)> = h_by_label.iter() + .map(|(l, &c)| (l.clone(), c)).collect(); + let s_entries: Vec<(Bm, f64)> = s_by_label.iter() + .map(|(l, &c)| (l.clone(), c)).collect(); + + for (p, _h_coeff) in &h_entries { + for (q, _s_coeff) in &s_entries { + if p.commutes_with(q) { + continue; + } + + // [H_P, S_Q] = i C_{Q, QP} (for anticommuting P,Q: [Q,P]=2QP) + // QP = i^k * R (from multiply_with_phase). + // Zassenhaus (1/2) factor: coeff = (1/2)·h·s·i·2·i^k = i^{k+1}·h·s + // For k=0: purely imaginary → zero real contribution at leading order. + // For k≠0: may have real part, but still O(ε^{3/2}). + let (qp, _phase) = q.multiply_with_phase(p); + c_generators.push((q.clone(), qp, 0.0)); + } + } + } + + // Merge real and imaginary H-type generators into complex coefficients. + // BCH2 can contribute both real and imaginary parts to generator labels. + // Merge BCH2 real parts into h_by_label. + for (label, &re) in &h_bch2_re_by_label { + *h_by_label.entry(label.clone()).or_insert(0.0) += re; + } + + let all_h_labels: std::collections::BTreeSet = h_by_label.keys() + .chain(h_imag_by_label.keys()) + .cloned() + .collect(); + + // Group BCH-combined generators by DEM event class. + // Store (real, imag) coefficient pairs per label. + let mut h_events: BTreeMap> = BTreeMap::new(); + let mut s_events: BTreeMap> = BTreeMap::new(); + let mut event_pauli_labels: BTreeMap> = BTreeMap::new(); + + for label in &all_h_labels { + let re = h_by_label.get(label).copied().unwrap_or(0.0); + let im = h_imag_by_label.get(label).copied().unwrap_or(0.0); + if re.abs() < 1e-20 && im.abs() < 1e-20 { + continue; + } + let event = classify(label, detectors, observables); + if event.detectors.is_empty() && event.observables.is_empty() { + continue; + } + h_events.entry(event.clone()).or_default().push((re, im)); + event_pauli_labels.entry(event).or_default().push(label.clone()); + } + + for (label, &coeff) in &s_by_label { + let event = classify(label, detectors, observables); + if event.detectors.is_empty() && event.observables.is_empty() { + continue; + } + s_events.entry(event).or_default().push(coeff); + } + + let mut entries = Vec::new(); + + // S-only events: exact formula + // p_D = (1/2)(1 - exp(2 * sum_rates)) + // Note: S rates are negative (e.g., -p/3), so 2*sum is negative, + // exp(2*sum) < 1, and p_D > 0. + for (event, rates) in &s_events { + let sum_rate: f64 = rates.iter().sum(); + let prob = (1.0 - (2.0 * sum_rate).exp()) / 2.0; + if prob.abs() > 1e-15 { + entries.push(DemEntry { event: event.clone(), probability: prob.abs() }); + } + } + + // C-type and A-type first-order contributions. + // β(ψ, C_{Q1,Q2}, P) = ±4 if [Q1,Q2]=0, [Q1,P]≠0, [Q2,P]≠0, Q1Q2|ψ⟩=∓|ψ⟩ + // β(ψ, A_{Q1,Q2}, P) = ±4 if [Q1,Q2]≠0, [Q1,P]≠0, [Q2,P]≠0, iQ1Q2|ψ⟩=±|ψ⟩ + // These contribute at first order (same as S). + if let Some(ref stab_group) = stabilizer_group { + for &(ref q1, ref q2, coeff) in c_generators.iter().chain(a_generators.iter()) { + // Classify: both Q1 and Q2 must anticommute with the same detectors + let event1 = classify(q1, detectors, observables); + let event2 = classify(q2, detectors, observables); + if event1 != event2 || (event1.detectors.is_empty() && event1.observables.is_empty()) { + continue; + } + let event = event1; + + // Check commutativity condition + let q1_q2_commute = q1.commutes_with(q2); + let is_c_type = c_generators.iter().any(|(a, b, _)| a == q1 && b == q2); + + // C requires [Q1,Q2]=0, A requires [Q1,Q2]≠0 + if is_c_type && !q1_q2_commute { continue; } + if !is_c_type && q1_q2_commute { continue; } + + // Check product stabilizer status + let product = q1.multiply(q2); + let beta = if product.is_identity() { + Some(true) + } else { + stab_group.is_stabilizer(&product) + }; + + // β = ±4, contribution to p_D = coeff * β / (-2) at first order + // (detection probability p = (1/2)(1 - ⟨Q⟩), ⟨Q⟩ ≈ 1 + β·ε) + // For C: β = ±4 → p contribution = -coeff * (±4) / 2 = ∓2·coeff + // For A: β = ±4 → same + if let Some(sign) = beta { + let beta_val = if sign { -4.0 } else { 4.0 }; + // For A-type, the stabilizer check is on iQ1Q2, not Q1Q2. + // Since we check Q1Q2, the sign interpretation differs for A. + // A: iQ1Q2|ψ⟩=±|ψ⟩ → Q1Q2|ψ⟩=∓i|ψ⟩. For real stabilizer + // eigenvalues (±1), this means Q1Q2 is NOT a real stabilizer. + // A-type only contributes when iQ1Q2 has eigenvalue ±1, + // which means Q1Q2 has eigenvalue ∓i. Skip for now since + // stabilizer eigenvalues are always ±1. + if !is_c_type { continue; } + + let prob_contribution = -coeff * beta_val / 2.0; + if prob_contribution.abs() > 1e-15 { + if let Some(existing) = entries.iter_mut().find(|e| e.event == event) { + let p_s = existing.probability; + existing.probability = p_s + prob_contribution.abs() - 2.0 * p_s * prob_contribution.abs(); + } else { + entries.push(DemEntry { event: event.clone(), probability: prob_contribution.abs() }); + } + } + } + } + } + + // H-only events: full leading-order formula with coherent interference. + // + // p_D = -(1/4) * sum_{j,k} h_j * h_k * beta(psi, C_{Qj,Qk}, P) + // + // beta(psi, C_{Q,Q'}, P) = -4 if [Q,Q']=0 and Q*Q'|psi>=+|psi> (stabilizer) + // = +4 if [Q,Q']=0 and Q*Q'|psi>=-|psi> (anti-stabilizer) + // = 0 otherwise + // + // Diagonal terms (j=k): Q*Q=I, always +1 stabilizer → beta=-4 → contributes +h_j^2 + // Off-diagonal with stabilizer product: contributes +h_j*h_k (constructive) + // Off-diagonal with anti-stabilizer: contributes -h_j*h_k (destructive) + // + // If stabilizer_group is None, fall back to diagonal approximation. + for (event, coeffs) in &h_events { + // Collect the detector stabilizers for this event (for ExactCommuting) + let event_det_stab = if h_formula == HFormula::ExactCommuting || h_formula == HFormula::ExactSubset { + // XOR of all detector stabilizers in this event + let mut stab = Bm::default(); + for &d_id in &event.detectors { + if let Some(det) = detectors.iter().find(|d| d.id == d_id) { + stab = stab.multiply(&det.stabilizer); + } + } + Some(stab) + } else { + None + }; + + let prob = if let Some(ref stab_group) = stabilizer_group { + compute_h_probability_full( + coeffs, generators, &event_pauli_labels, event, + stab_group, h_formula, event_det_stab.as_ref(), + ) + } else { + coeffs.iter().map(|&(re, im)| re * re + im * im).sum() + }; + if prob > 1e-15 { + if let Some(existing) = entries.iter_mut().find(|e| e.event == *event) { + let p_s = existing.probability; + existing.probability = p_s + prob - 2.0 * p_s * prob; + } else { + entries.push(DemEntry { event: event.clone(), probability: prob }); + } + } + } + + entries +} + +/// Compute H-type event probability using the full beta function. +/// +/// p_D = -(1/4) * sum_{j,k} h_j * h_k * beta(psi, C_{Qj,Qk}, P) +/// +/// For each pair (j,k): +/// - If [Q_j, Q_k] ≠ 0: beta = 0 +/// - If [Q_j, Q_k] = 0 and Q_j*Q_k is +1 stabilizer: beta = -4 → +h_j*h_k +/// - If [Q_j, Q_k] = 0 and Q_j*Q_k is -1 stabilizer: beta = +4 → -h_j*h_k +/// - Otherwise: beta = 0 +fn compute_h_probability_full( + coeffs: &[(f64, f64)], + _generators: &[PropagatedEeg], + event_labels: &BTreeMap>, + event: &DemEvent, + stab_group: &StabilizerGroup, + h_formula: HFormula, + det_stabilizer: Option<&Bm>, +) -> f64 { + let labels = match event_labels.get(event) { + Some(l) => l, + None => return 0.0, + }; + + let n = coeffs.len(); + + // --- ExactCommuting: product formula for commuting generators --- + if h_formula == HFormula::ExactCommuting { + if let Some(det_stab) = det_stabilizer { + return compute_exact_commuting(coeffs, labels, stab_group, det_stab); + } + } + + // --- ExactSubset: enumerate all even-size subsets --- + if h_formula == HFormula::ExactSubset { + if let Some(det_stab) = det_stabilizer { + return compute_exact_subset(coeffs, labels, stab_group, det_stab); + } + } + + // --- Taylor or SinSquared: quadratic form with beta --- + let mut total = 0.0_f64; + + for j in 0..n { + for k in 0..n { + let (re_j, im_j) = coeffs[j]; + let (re_k, im_k) = coeffs[k]; + let re_product = re_j * re_k - im_j * im_k; + + if j == k { + total += re_j * re_j + im_j * im_j; + } else { + let q_j = &labels[j]; + let q_k = &labels[k]; + + if !q_j.commutes_with(q_k) { + continue; + } + + let product = q_j.multiply(q_k); + + if product.is_identity() { + total += re_product; + continue; + } + + match stab_group.is_stabilizer(&product) { + Some(true) => { total += re_product; } + Some(false) => { total -= re_product; } + None => {} + } + } + } + } + + let total = total.max(0.0); + + match h_formula { + HFormula::Taylor => total, + HFormula::SinSquared => { + let h_eff = total.sqrt(); + h_eff.sin().powi(2) + } + HFormula::ExactCommuting | HFormula::ExactSubset => total, // fallback if no detector + } +} + +/// Exact product formula for commuting H-type generators. +/// +/// For each generator P_j with rate h_j: +/// - If P_j is a ±1 stabilizer: factor = exp(±2i h_j) → contributes to phase +/// - If D·P_j is a ±1 stabilizer: factor = exp(∓2i h_j) → contributes to phase +/// - Neither: factor = cos(2h_j) → real damping +/// +/// p_D = (1/2)(1 - Re(prod_j factor_j)) +fn compute_exact_commuting( + coeffs: &[(f64, f64)], + labels: &[Bm], + stab_group: &StabilizerGroup, + det_stab: &Bm, +) -> f64 { + let n = coeffs.len(); + // Accumulate product as (real, imag) complex number + let mut prod_re = 1.0_f64; + let mut prod_im = 0.0_f64; + + for j in 0..n { + let (h_re, h_im) = coeffs[j]; + // For simplicity, use magnitude of complex coefficient + let h = (h_re * h_re + h_im * h_im).sqrt(); + if h < 1e-20 { continue; } + + let label = &labels[j]; + + // Check if P_j is a stabilizer (directly in expanded frame) + let p_stab = if label.is_identity() { + Some(true) + } else { + stab_group.is_stabilizer(label) + }; + + let (factor_re, factor_im) = if let Some(sign) = p_stab { + let s = if sign { 1.0 } else { -1.0 }; + let angle = 2.0 * s * h; + (angle.cos(), angle.sin()) + } else { + // Check D·P_j + let dp = det_stab.multiply(label); + let dp_stab = if dp.is_identity() { + Some(true) + } else { + stab_group.is_stabilizer(&dp) + }; + + if let Some(sign) = dp_stab { + let s = if sign { 1.0 } else { -1.0 }; + let angle = -2.0 * s * h; + (angle.cos(), angle.sin()) + } else { + ((2.0 * h).cos(), 0.0) + } + }; + + // Complex multiply: prod *= factor + let new_re = prod_re * factor_re - prod_im * factor_im; + let new_im = prod_re * factor_im + prod_im * factor_re; + prod_re = new_re; + prod_im = new_im; + } + + // p_D = (1/2)(1 - Re(product)) + let prob = 0.5 * (1.0 - prod_re); + prob.max(0.0) +} + +/// Exact subset-sum formula for commuting H-type generators. +/// +/// Enumerates ALL even-size subsets S of generators. For each: +/// coefficient = i^|S| · Π_{j∈S} sin(2h_j) · Π_{j∉S} cos(2h_j) +/// eigenvalue = ε_S = ⟨ψ|(Π_{j∈S} P_j)·D|ψ⟩ +/// +/// p_D = (1/2)(1 - Re(Σ_S coefficient · ε_S)) +/// +/// Only even-|S| subsets contribute to Re (odd powers of i are imaginary). +/// This captures all orders of multi-body interference. Exact when all +/// generators commute. Cost: O(2^N) where N = number of generators. +fn compute_exact_subset( + coeffs: &[(f64, f64)], + labels: &[Bm], + stab_group: &StabilizerGroup, + det_stab: &Bm, +) -> f64 { + let n = coeffs.len(); + + // Guard: too many generators → fall back to ExactCommuting + if n > 25 { + return compute_exact_commuting(coeffs, labels, stab_group, det_stab); + } + + // Precompute sin(2h_j) and cos(2h_j) for each generator + let mut sin2h = Vec::with_capacity(n); + let mut cos2h = Vec::with_capacity(n); + for j in 0..n { + let (h_re, h_im) = coeffs[j]; + let h = (h_re * h_re + h_im * h_im).sqrt(); + sin2h.push((2.0 * h).sin()); + cos2h.push((2.0 * h).cos()); + } + + // The empty set (S = {}) contributes: Π cos(2h_j) · ε_{D} + // D itself should be a stabilizer with eigenvalue +1 (no error → ⟨D⟩=1). + let all_cos: f64 = cos2h.iter().product(); + + let mut sum_re = all_cos; // |S|=0 contribution + + // Enumerate all non-empty even-size subsets via bitmask + // For |S| even: i^|S| has Re = (-1)^{|S|/2} + let total_subsets = 1u64 << n; + for mask in 1..total_subsets { + let size = mask.count_ones() as usize; + if size % 2 != 0 { + continue; // odd-size subsets have Im(i^|S|) only → Re = 0 + } + + // Compute product of labels in S, multiplied by det_stab (D) + let mut product = det_stab.clone(); + for j in 0..n { + if mask & (1u64 << j) != 0 { + product = product.multiply(&labels[j]); + } + } + + // Check if this product is a stabilizer + let eigenvalue = if product.is_identity() { + Some(true) + } else { + stab_group.is_stabilizer(&product) + }; + + let epsilon = match eigenvalue { + Some(true) => 1.0, + Some(false) => -1.0, + None => continue, // not a stabilizer, ε=0 + }; + + // Coefficient: (-1)^{|S|/2} · Π_{j∈S} sin(2h_j) · Π_{j∉S} cos(2h_j) + let sign = if (size / 2) % 2 == 0 { 1.0 } else { -1.0 }; + + let mut coeff = sign; + for j in 0..n { + if mask & (1u64 << j) != 0 { + coeff *= sin2h[j]; + } else { + coeff *= cos2h[j]; + } + } + + sum_re += coeff * epsilon; + } + + let prob = 0.5 * (1.0 - sum_re); + prob.max(0.0) +} + +/// Sensitivity matrix M_E for a DEM event E (Hines Eq. 21). +/// +/// M_E encodes how physical-level Hamiltonian error parameters affect the +/// probability of event E: p_E = -(1/2) θ^T M_E θ. +/// +/// The matrix is indexed by `NoiseSource` pairs. Each entry M[i,j] = b_{P,Q_i,Q_j} +/// where b is the beta coefficient for the generator pair (Q_i, Q_j) and P is +/// the detector for event E. +/// +/// Returns: Vec of (source_i, source_j, value) triplets for non-zero entries. +#[must_use] +pub fn sensitivity_matrix( + generators: &[crate::circuit::PropagatedEeg], + detectors: &[Detector], + observables: &[Observable], + stabilizer_group: Option<&StabilizerGroup>, +) -> BTreeMap> { + use crate::circuit::NoiseSource; + use crate::eeg::EegType; + + let mut result = BTreeMap::new(); + + // Collect H generators with their sources + let h_gens: Vec<_> = generators.iter() + .filter(|g| g.eeg_type == EegType::H && g.source.is_some()) + .collect(); + + // Group by event class + let mut event_gens: BTreeMap> = BTreeMap::new(); + for g in &h_gens { + let event = classify(&g.label, detectors, observables); + if event.detectors.is_empty() && event.observables.is_empty() { + continue; + } + event_gens.entry(event).or_default().push(( + g.label.clone(), + g.coeff, + g.source.clone().unwrap(), + )); + } + + // For each event class, build the sensitivity matrix + for (event, gens) in &event_gens { + let mut entries = Vec::new(); + + for i in 0..gens.len() { + for j in 0..gens.len() { + let (ref label_i, _coeff_i, ref src_i) = gens[i]; + let (ref label_j, _coeff_j, ref src_j) = gens[j]; + + // Beta coefficient for pair (i,j) + let beta_val: f64 = if i == j { + 1.0 // diagonal: beta = -4, but -(1/4)*(-4) = 1 + } else { + if !label_i.commutes_with(label_j) { + 0.0 + } else { + let product = label_i.multiply(label_j); + if product.is_identity() { + 1.0 + } else if let Some(stab) = stabilizer_group { + match stab.is_stabilizer(&product) { + Some(true) => 1.0, + Some(false) => -1.0, + None => 0.0, + } + } else { + 0.0 + } + } + }; + + if beta_val.abs() > 1e-15_f64 { + entries.push((src_i.clone(), src_j.clone(), beta_val)); + } + } + } + + if !entries.is_empty() { + result.insert(event.clone(), entries); + } + } + + result +} + +/// Build a decomposable DEM from propagated EEG generators. +/// +/// Same as `build_dem_configured` but includes X/Z component decomposition +/// for each mechanism, enabling proper graphlike decomposition for MWPM decoders. +pub fn build_dem_decomposable( + generators: &[PropagatedEeg], + detectors: &[Detector], + observables: &[Observable], + stabilizer_group: Option<&StabilizerGroup>, + config: &EegConfig, +) -> Vec { + // First, build the standard DEM entries with the requested config + let standard_entries = build_dem_configured( + generators, detectors, observables, stabilizer_group, config, + ); + + // Build a map from combined event → (x_component, z_component) + // by classifying each unique label's X/Z components. + // Multiple generators may contribute to the same event, but their + // X/Z classification should be consistent (same combined effect = same decomposition). + let mut event_xz: BTreeMap< + (SmallVec<[usize; 4]>, SmallVec<[usize; 2]>), + (Option, Option), + > = BTreeMap::new(); + + for g in generators { + let (combined, x_ev, z_ev) = classify_xz(&g.label, detectors, observables); + let key = (combined.detectors.clone(), combined.observables.clone()); + // First generator for this event wins (they should all agree) + event_xz.entry(key).or_insert((x_ev, z_ev)); + } + + // Convert standard entries to decomposable entries + standard_entries.into_iter().map(|entry| { + let key = (entry.event.detectors.clone(), entry.event.observables.clone()); + let (x_comp, z_comp) = event_xz + .get(&key) + .cloned() + .unwrap_or((None, None)); + DecomposableDemEntry { + event: entry.event, + probability: entry.probability, + x_component: x_comp, + z_component: z_comp, + } + }).collect() +} + +/// Format DEM entries as a Stim-compatible string. +#[must_use] +pub fn format_dem(entries: &[DemEntry]) -> String { + let mut lines = Vec::new(); + for entry in entries { + let mut parts = Vec::new(); + for &d in &entry.event.detectors { + parts.push(format!("D{d}")); + } + for &o in &entry.event.observables { + parts.push(format!("L{o}")); + } + if !parts.is_empty() { + lines.push(format!("error({:.6e}) {}", entry.probability, parts.join(" "))); + } + } + lines.join("\n") +} + +/// Format a list of decomposable DEM entries into a graphlike DEM string. +/// +/// Mechanisms with both X and Z components are output as `error(p) x_targets ^ z_targets`. +/// Single-component mechanisms with ≤ 2 detectors are output directly. +/// Single-component hyperedges (3+ detectors) are decomposed via a graphlike +/// index: expressed as XOR of existing graphlike mechanisms. If no decomposition +/// exists, the mechanism is dropped (cannot be used by MWPM decoders). +pub fn format_dem_decomposed(entries: &[DecomposableDemEntry]) -> String { + use std::collections::{BTreeMap, BTreeSet}; + + fn format_event(ev: &DemEvent) -> String { + let mut parts = Vec::new(); + for &d in &ev.detectors { + parts.push(format!("D{d}")); + } + for &o in &ev.observables { + parts.push(format!("L{o}")); + } + parts.join(" ") + } + + fn is_graphlike(ev: &DemEvent) -> bool { + ev.detectors.len() <= 2 + } + + // Step 1: Collect all graphlike mechanisms (building blocks for decomposition) + let mut graphlike_set: BTreeSet> = BTreeSet::new(); + for entry in entries { + if entry.probability <= 0.0 { continue; } + // Collect graphlike from X/Z components + if let Some(ref x) = entry.x_component { + if is_graphlike(x) && !x.detectors.is_empty() { + graphlike_set.insert(x.detectors.clone()); + } + } + if let Some(ref z) = entry.z_component { + if is_graphlike(z) && !z.detectors.is_empty() { + graphlike_set.insert(z.detectors.clone()); + } + } + // Also from combined event + if is_graphlike(&entry.event) && !entry.event.detectors.is_empty() { + graphlike_set.insert(entry.event.detectors.clone()); + } + } + + // Step 2: Build index for graphlike decomposition search + let max_det = graphlike_set.iter() + .flat_map(|d| d.iter().copied()) + .max() + .unwrap_or(0); + let mut by_det: Vec>> = vec![Vec::new(); max_det + 1]; + for g in &graphlike_set { + for &d in g.iter() { + by_det[d].push(g.clone()); + } + } + + // Search for decomposition of a hyperedge into XOR of graphlike pieces + fn search_decomp( + remaining: &SmallVec<[usize; 4]>, + by_det: &[Vec>], + graphlike_set: &BTreeSet>, + memo: &mut BTreeMap, Option>>>, + ) -> Option>> { + if let Some(cached) = memo.get(remaining) { + return cached.clone(); + } + if remaining.is_empty() { + let r = Some(Vec::new()); + memo.insert(remaining.clone(), r.clone()); + return r; + } + if remaining.len() <= 2 && graphlike_set.contains(remaining) { + let r = Some(vec![remaining.clone()]); + memo.insert(remaining.clone(), r.clone()); + return r; + } + + let pivot = remaining[0]; + if pivot >= by_det.len() { + memo.insert(remaining.clone(), None); + return None; + } + + for candidate in &by_det[pivot] { + // Candidate detectors must be subset of remaining + if !candidate.iter().all(|d| remaining.contains(d)) { + continue; + } + // XOR: remove shared detectors, keep symmetric difference + let mut next: SmallVec<[usize; 4]> = SmallVec::new(); + let mut i = 0; + let mut j = 0; + let r = remaining; + let c = candidate; + while i < r.len() && j < c.len() { + if r[i] < c[j] { next.push(r[i]); i += 1; } + else if r[i] > c[j] { next.push(c[j]); j += 1; } + else { i += 1; j += 1; } // shared → cancel + } + while i < r.len() { next.push(r[i]); i += 1; } + while j < c.len() { next.push(c[j]); j += 1; } + + if next.len() >= remaining.len() { continue; } // must make progress + + if let Some(suffix) = search_decomp(&next, by_det, graphlike_set, memo) { + let mut result = vec![candidate.clone()]; + result.extend(suffix); + result.sort(); + let r = Some(result); + memo.insert(remaining.clone(), r.clone()); + return r; + } + } + + memo.insert(remaining.clone(), None); + None + } + + // Step 3: Format entries + let mut by_targets: BTreeMap = BTreeMap::new(); + let mut memo: BTreeMap, Option>>> = BTreeMap::new(); + + for entry in entries { + if entry.probability <= 0.0 { + continue; + } + + let targets = match (&entry.x_component, &entry.z_component) { + (Some(x), Some(z)) if !x.detectors.is_empty() && !z.detectors.is_empty() => { + // Both components non-empty: decompose as X ^ Z + let x_str = format_event(x); + let z_str = format_event(z); + if x_str == z_str { + x_str + } else { + format!("{x_str} ^ {z_str}") + } + } + (Some(x), _) if !x.detectors.is_empty() || !x.observables.is_empty() => { + if is_graphlike(x) { + format_event(x) + } else { + // Hyperedge X-only: try graphlike decomposition + match search_decomp(&x.detectors, &by_det, &graphlike_set, &mut memo) { + Some(pieces) => { + let mut parts: Vec = pieces.iter().map(|p| { + p.iter().map(|d| format!("D{d}")).collect::>().join(" ") + }).collect(); + // Attach observables to first piece + if !x.observables.is_empty() && !parts.is_empty() { + for &o in &x.observables { + parts[0].push_str(&format!(" L{o}")); + } + } + parts.join(" ^ ") + } + None => continue, // drop undecomposable mechanisms + } + } + } + (_, Some(z)) if !z.detectors.is_empty() || !z.observables.is_empty() => { + if is_graphlike(z) { + format_event(z) + } else { + // Hyperedge Z-only: try graphlike decomposition + match search_decomp(&z.detectors, &by_det, &graphlike_set, &mut memo) { + Some(pieces) => { + let mut parts: Vec = pieces.iter().map(|p| { + p.iter().map(|d| format!("D{d}")).collect::>().join(" ") + }).collect(); + if !z.observables.is_empty() && !parts.is_empty() { + for &o in &z.observables { + parts[0].push_str(&format!(" L{o}")); + } + } + parts.join(" ^ ") + } + None => continue, // drop undecomposable mechanisms + } + } + } + _ => { + if is_graphlike(&entry.event) { + format_event(&entry.event) + } else { + // Combined hyperedge without components: try graphlike decomposition + match search_decomp(&entry.event.detectors, &by_det, &graphlike_set, &mut memo) { + Some(pieces) => { + let mut parts: Vec = pieces.iter().map(|p| { + p.iter().map(|d| format!("D{d}")).collect::>().join(" ") + }).collect(); + if !entry.event.observables.is_empty() && !parts.is_empty() { + for &o in &entry.event.observables { + parts[0].push_str(&format!(" L{o}")); + } + } + parts.join(" ^ ") + } + None => continue, + } + } + } + }; + + if targets.is_empty() { + continue; + } + + by_targets + .entry(targets) + .and_modify(|p| { + *p = *p + entry.probability - 2.0 * *p * entry.probability; + }) + .or_insert(entry.probability); + } + + let mut lines = Vec::new(); + for (targets, prob) in &by_targets { + if *prob > 0.0 { + lines.push(format!("error({prob:.6e}) {targets}")); + } + } + lines.join("\n") +} + +#[cfg(test)] +mod tests { + use super::*; + + fn z_det(id: usize, qubits: &[usize]) -> Detector { + let mut bm = Bm::default(); + for &q in qubits { + bm.z_bits.set_bit(q); + } + Detector { id, stabilizer: bm } + } + + #[test] + fn test_s_only_probability() { + // Single S_X with rate -0.01 → p ≈ 0.00995 + let gens = vec![PropagatedEeg { + eeg_type: EegType::S, + label: Bm::x(0), + label2: None, + coeff: -0.01, + source: None, }]; + let dets = vec![z_det(0, &[0])]; // Z0 anticommutes with X0 + let entries = build_dem(&gens, &dets, &[]); + + assert_eq!(entries.len(), 1); + let expected = (1.0 - (-0.02_f64).exp()) / 2.0; + assert!((entries[0].probability - expected).abs() < 1e-6); + } + + #[test] + fn test_h_diagonal_probability() { + // H_X with rate 0.1 → p = 0.1^2 = 0.01 (diagonal approx) + let gens = vec![PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: 0.1, + source: None, }]; + let dets = vec![z_det(0, &[0])]; + let entries = build_dem(&gens, &dets, &[]); + + assert_eq!(entries.len(), 1); + assert!((entries[0].probability - 0.01).abs() < 1e-10); + } + + #[test] + fn test_h_multiple_same_event() { + // Two H generators in same event class: rates don't add (diagonal approx) + // p = h1^2 + h2^2 (NOT (h1+h2)^2 — that would be coherent accumulation) + let gens = vec![ + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.1 , source: None }, + PropagatedEeg { eeg_type: EegType::H, label: Bm::y(0), label2: None, coeff: 0.05 , source: None }, + ]; + let dets = vec![z_det(0, &[0])]; // Both X0 and Y0 anticommute with Z0 + let entries = build_dem(&gens, &dets, &[]); + + // Diagonal: p = 0.1^2 + 0.05^2 = 0.01 + 0.0025 = 0.0125 + assert_eq!(entries.len(), 1); + assert!((entries[0].probability - 0.0125).abs() < 1e-10); + } + + #[test] + fn test_z_invisible_to_z_detector() { + // H_Z should NOT flip a Z-type detector (Z commutes with Z) + let gens = vec![PropagatedEeg { + eeg_type: EegType::H, + label: Bm::z(0), + label2: None, + coeff: 0.1, + source: None, }]; + let dets = vec![z_det(0, &[0])]; + let entries = build_dem(&gens, &dets, &[]); + + assert!(entries.is_empty(), "Z should not flip Z detector"); + } + + #[test] + fn test_bch_same_label_accumulation() { + // Two H generators with SAME Pauli label: BCH sums coefficients. + // Two H_X(0) with rates 0.1 and 0.05 → combined rate 0.15 → p = 0.15^2 + let gens = vec![ + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.1 , source: None }, + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.05 , source: None }, + ]; + let dets = vec![z_det(0, &[0])]; + let entries = build_dem(&gens, &dets, &[]); + + // BCH combines: single generator with rate 0.15, p = 0.15^2 = 0.0225 + assert_eq!(entries.len(), 1); + assert!((entries[0].probability - 0.0225).abs() < 1e-10, + "BCH should sum same-label rates: got {}", entries[0].probability); + } + + #[test] + fn test_beta_constructive_interference() { + // Two H generators Q1=X0, Q2=X1 in same event class (both flip Z0Z1). + // Q1*Q2 = X0X1. State is |Phi+> Bell state → X0X1 is +1 stabilizer. + // Constructive: p = (h1+h2)^2 + use crate::stabilizer::StabilizerGroup; + use pecos_core::gate_type::GateType; + use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; + + fn g(gt: GateType, qs: &[usize]) -> Gate { + Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qs.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), + } + } + + let gens = vec![ + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.1 , source: None }, + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(1), label2: None, coeff: 0.05 , source: None }, + ]; + // Z0Z1 detector: X0 and X1 both anticommute with it + let dets = vec![Detector { id: 0, stabilizer: Bm::z(0).multiply(&Bm::z(1)) }]; + + // |Phi+> = H CX |00> → stabilizers +X0X1, +Z0Z1 + let stab_group = StabilizerGroup::from_circuit( + &[g(GateType::H, &[0]), g(GateType::CX, &[0, 1])], 2, + ); + + let entries = build_dem_with_stabilizers(&gens, &dets, &[], Some(&stab_group)); + + assert_eq!(entries.len(), 1); + // X0*X1 is +1 stabilizer → constructive: (0.1+0.05)^2 = 0.0225 + assert!((entries[0].probability - 0.0225).abs() < 1e-10, + "Constructive beta: got {}, expected 0.0225", entries[0].probability); + } + + #[test] + fn test_beta_destructive_interference() { + // Same event class but |Phi-> state → X0X1 is -1 stabilizer. + // Destructive: p = (h1-h2)^2 + use crate::stabilizer::StabilizerGroup; + use pecos_core::gate_type::GateType; + use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; + + fn g(gt: GateType, qs: &[usize]) -> Gate { + Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qs.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), + } + } + + let gens = vec![ + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.1 , source: None }, + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(1), label2: None, coeff: 0.05 , source: None }, + ]; + let dets = vec![Detector { id: 0, stabilizer: Bm::z(0).multiply(&Bm::z(1)) }]; + + // |Phi-> = CX H X |00> → stabilizers -X0X1, +Z0Z1 + let stab_group = StabilizerGroup::from_circuit( + &[g(GateType::X, &[0]), g(GateType::H, &[0]), g(GateType::CX, &[0, 1])], 2, + ); + + let entries = build_dem_with_stabilizers(&gens, &dets, &[], Some(&stab_group)); + + assert_eq!(entries.len(), 1); + // X0*X1 is -1 stabilizer → destructive: (0.1-0.05)^2 = 0.0025 + assert!((entries[0].probability - 0.0025).abs() < 1e-10, + "Destructive beta: got {}, expected 0.0025", entries[0].probability); + } + + #[test] + fn test_beta_equal_rates_destructive_cancels() { + // h1 = h2 = 0.1, -1 stabilizer product → p = (h1-h2)^2 = 0 + use crate::stabilizer::StabilizerGroup; + use pecos_core::gate_type::GateType; + use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; + + fn g(gt: GateType, qs: &[usize]) -> Gate { + Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qs.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), + } + } + + let gens = vec![ + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.1 , source: None }, + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(1), label2: None, coeff: 0.1 , source: None }, + ]; + let dets = vec![Detector { id: 0, stabilizer: Bm::z(0).multiply(&Bm::z(1)) }]; + + let stab_group = StabilizerGroup::from_circuit( + &[g(GateType::X, &[0]), g(GateType::H, &[0]), g(GateType::CX, &[0, 1])], 2, + ); + + let entries = build_dem_with_stabilizers(&gens, &dets, &[], Some(&stab_group)); + + // Complete cancellation: p = 0 + assert!(entries.is_empty(), + "Equal-rate destructive interference should cancel completely"); + } + + #[test] + fn test_beta_no_stabilizer_diagonal() { + // When product is NOT in stabilizer group, beta = 0, fall back to diagonal. + // X0 and X1 both flip Z0Z1 detector. Product X0X1. + // State |00> has stabilizers Z0, Z1. X0X1 is not a stabilizer. + use crate::stabilizer::StabilizerGroup; + + let gens = vec![ + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.1 , source: None }, + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(1), label2: None, coeff: 0.05 , source: None }, + ]; + let dets = vec![Detector { id: 0, stabilizer: Bm::z(0).multiply(&Bm::z(1)) }]; + + let stab_group = StabilizerGroup::from_circuit(&[], 2); + + let entries = build_dem_with_stabilizers(&gens, &dets, &[], Some(&stab_group)); + + assert_eq!(entries.len(), 1); + // p = h1^2 + h2^2 = 0.0125 (diagonal only) + assert!((entries[0].probability - 0.0125).abs() < 1e-10, + "Non-stabilizer product → diagonal: got {}", entries[0].probability); + } + + #[test] + fn test_s_exact_formula_multiple() { + // Multiple S generators in same event class: exact formula + // p = (1/2)(1 - exp(2 * sum_rates)) + let gens = vec![ + PropagatedEeg { eeg_type: EegType::S, label: Bm::x(0), label2: None, coeff: -0.01 , source: None }, + PropagatedEeg { eeg_type: EegType::S, label: Bm::y(0), label2: None, coeff: -0.005 , source: None }, + ]; + let dets = vec![z_det(0, &[0])]; + let entries = build_dem(&gens, &dets, &[]); + + assert_eq!(entries.len(), 1); + // sum_rates = -0.01 + -0.005 = -0.015 (same event class, both flip Z0) + let expected = (1.0 - (2.0 * -0.015_f64).exp()) / 2.0; + assert!((entries[0].probability - expected).abs() < 1e-10); + } + + #[test] + fn test_observable_classification() { + // Generator that flips an observable but no detectors + let gens = vec![PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: 0.1, + source: None, }]; + let dets = vec![z_det(0, &[1])]; // Detector on qubit 1 + let obs = vec![Observable { id: 0, pauli: Bm::z(0) }]; // Observable Z0 + + let entries = build_dem(&gens, &dets, &obs); + + // X0 anticommutes with Z0 (observable) but not with Z1 (detector) + assert_eq!(entries.len(), 1); + assert!(entries[0].event.detectors.is_empty()); + assert_eq!(entries[0].event.observables.as_slice(), &[0]); + } + + #[test] + fn test_bch2_anticommuting_h_generators() { + // Two H generators with anticommuting labels: H_X and H_Z on same qubit. + // [H_X, H_Z] = -2i H_{XZ} = -2i H_Y → BCH2 adds imaginary H_Y. + // BCH coefficient: -i * h_X * h_Z. + // + // Both X and Z flip the Z detector. Y also flips Z detector. + // The imaginary BCH2 generator contributes to probability via + // re_product = re_j * re_k - im_j * im_k. + // + // Diagonal of imaginary generator: |im|² = (h_X * h_Z)². + // Cross with real generators: Re(re * (-im)) = re * im (but im is negative). + let h_x = 0.1; + let h_z = 0.05; + + let gens = vec![ + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: h_x, source: None }, + PropagatedEeg { eeg_type: EegType::H, label: Bm::z(0), label2: None, coeff: h_z, source: None }, + ]; + let dets = vec![z_det(0, &[0])]; // Z detector: X and Y anticommute, Z commutes + + // Without BCH2: only X flips detector. p = h_x² = 0.01 + let entries_k1 = build_dem_with_options( + &gens, &dets, &[], None, HFormula::Taylor, BchOrder::First, + ); + let p_k1: f64 = entries_k1.iter().map(|e| e.probability).sum(); + assert!((p_k1 - h_x * h_x).abs() < 1e-10, + "BCH1: p should be h_x² = {}, got {p_k1}", h_x * h_x); + + // With BCH2: adds H_Y with imaginary coeff -i * h_x * h_z. + // Y anticommutes with Z detector → flips it. + // Diagonal of imaginary Y: (h_x * h_z)² = 0.000025. + // Cross-term X with imaginary Y: Re(h_x * (i * h_x * h_z)) = 0 (imaginary × real = imaginary, Re=0) + // Wait, im_Y = -h_x * h_z (negative, from sign fix). Cross: re_X * re_Y - im_X * im_Y. + // re_X = h_x, im_X = 0. re_Y = 0, im_Y = -h_x*h_z. + // re_product = h_x * 0 - 0 * (-h_x*h_z) = 0. Cross-term is zero. + // So BCH2 only adds the diagonal of the Y generator: |im_Y|² = (h_x * h_z)² = 0.000025. + let entries_k2 = build_dem_with_options( + &gens, &dets, &[], None, HFormula::Taylor, BchOrder::Second, + ); + let p_k2: f64 = entries_k2.iter().map(|e| e.probability).sum(); + let expected_k2 = h_x * h_x + (h_x * h_z).powi(2); + assert!((p_k2 - expected_k2).abs() < 1e-10, + "BCH2: p should be h_x² + (h_x·h_z)² = {expected_k2}, got {p_k2}"); + + // BCH2 adds a small correction: 0.01 + 0.000025 = 0.010025 + assert!(p_k2 > p_k1, "BCH2 should add to probability"); + } +} diff --git a/exp/pecos-eeg/src/dem_simulator.rs b/exp/pecos-eeg/src/dem_simulator.rs new file mode 100644 index 000000000..7d028b236 --- /dev/null +++ b/exp/pecos-eeg/src/dem_simulator.rs @@ -0,0 +1,446 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! DEM-based simulator: samples from a Detector Error Model and synthesizes +//! physical measurement bitstrings. +//! +//! This module provides the pure Rust implementation of DEM-based simulation. +//! Given a circuit (as `Vec`) and noise parameters, it: +//! 1. Builds a DEM via the EEG coherent backward mechanism extraction +//! 2. Samples detection events from the DEM +//! 3. Synthesizes physical measurement bitstrings matching the circuit's output +//! +//! # Performance +//! +//! The sampling step uses `ParsedDem::sample()` which is O(mechanisms) per shot. +//! For bulk sampling, use `to_dem_sampler()` for columnar bit-packed SIMD sampling. + +use crate::dem_generator::{DemContext, DemGenerator}; +use crate::expand::{ExpandedCircuit, GateIndex}; +use crate::noise::UniformNoise; +use pecos_core::gate_type::GateType; +use pecos_core::pauli::pauli_bitmask::BitmaskStorage; +use pecos_core::Gate; +use pecos_qec::fault_tolerance::dem_builder::ParsedDem; +use pecos_quantum::TickCircuit; +use pecos_random::PecosRng; + +/// Metadata needed for measurement synthesis. +#[derive(Clone, Debug)] +pub struct CircuitMeasurementMeta { + /// Total number of physical measurements in the circuit. + pub num_measurements: usize, + /// Detector definitions: each is a list of measurement record offsets. + /// Offset is relative: absolute_index = num_measurements + offset. + pub detector_records: Vec>, + /// Observable definitions: same format as detectors. + pub observable_records: Vec>, +} + +/// Result of a DEM simulation run. +pub struct DemSimulationResult { + /// Per-shot measurement bitstrings (same format as gate-by-gate simulators). + pub measurements: Vec>, +} + +/// Run DEM-based simulation: build DEM, sample, produce measurement bitstrings. +/// +/// Two modes: +/// 1. **Stochastic path** (idle_rz == 0): builds a TickCircuit from gates + metadata, +/// uses `DemSampler::from_tick_circuit` with `OutputMode::RawMeasurements` for +/// proper non-deterministic handling and maximum performance. +/// 2. **Coherent path** (idle_rz > 0): uses EEG DemGenerator for DEM, then +/// ParsedDem sampler + measurement synthesis (EEG handles coherent noise). +/// +/// # Arguments +/// * `gates` - Circuit gates (from CommandQueue conversion) +/// * `noise` - Noise parameters +/// * `meta` - Circuit measurement metadata (num_measurements, detector/observable records) +/// * `generator` - Which DEM generator to use (for coherent path) +/// * `shots` - Number of shots to sample +/// * `seed` - Random seed +pub fn run_dem_simulation( + gates: &[Gate], + noise: &UniformNoise, + meta: &CircuitMeasurementMeta, + generator: &dyn DemGenerator, + shots: usize, + seed: u64, +) -> DemSimulationResult { + // Coherent noise: use EEG path (Heisenberg walks handle idle_rz) + if noise.idle_rz.abs() > 1e-15 { + return run_eeg_path(gates, noise, meta, generator, shots, seed); + } + + // Stochastic: use proper DemSampler with raw measurement output + try_stochastic_path(gates, noise, meta, shots, seed) + .expect("DEM simulation failed: could not build TickCircuit or DemSampler from circuit") +} + +/// Stochastic raw measurement path via RawMeasurementPlan. +/// +/// Builds a TickCircuit, runs symbolic simulation for MeasurementHistory, +/// then uses fault_sampler::RawMeasurementPlan for: +/// - Correct cross-reset measurement correlations (via SymbolicSparseStab PZ) +/// - Geometric/O(fired) fault sampling +/// - Raw measurement output matching gate-by-gate simulators +/// +/// Returns None if idle_rz > 0 (needs EEG path for coherent noise). +fn try_stochastic_path( + gates: &[Gate], + noise: &UniformNoise, + meta: &CircuitMeasurementMeta, + shots: usize, + seed: u64, +) -> Option { + // Only use stochastic path when no coherent noise + if noise.idle_rz.abs() > 1e-15 { + return None; + } + + // Build TickCircuit using typed API (proper measurement record tracking) + let mut tc = build_tick_circuit(gates, meta)?; + + // Compact ticks to reduce DAG complexity (critical for performance) + tc.compact_ticks(); + + // Build raw measurement plan via shared symbolic sim + fault table + use pecos_qec::fault_tolerance::fault_sampler::{ + symbolic_measurement_history, RawMeasurementPlan, StochasticNoiseParams, + }; + + let history = symbolic_measurement_history(&tc).ok()?; + + let noise_params = StochasticNoiseParams { + p1: noise.p1, + p2: noise.p2, + p_meas: noise.p_meas, + p_prep: noise.p_prep, + }; + let mechanisms = + pecos_qec::fault_tolerance::fault_sampler::build_fault_table(&tc, &noise_params).ok()?; + let plan = RawMeasurementPlan::new(&history, mechanisms); + + // Sample raw measurements (columnar, then extract rows) + let result = plan.sample(shots, seed); + let mut measurements = Vec::with_capacity(shots); + for shot in 0..shots { + let n = result.num_measurements(); + let mut meas = Vec::with_capacity(n); + for m in 0..n { + meas.push(u8::from(result.get(shot, m).0)); + } + measurements.push(meas); + } + + Some(DemSimulationResult { measurements }) +} + +/// Build a TickCircuit from flat gates + metadata using the typed API. +/// +/// Uses `.mz()` for measurement gates (properly tracks measurement records), +/// `.pz()` for prep gates, and `try_add_gate()` for all other gates. +/// After building all gates, creates detector/observable annotations using +/// the stored measurement references. This ensures the DagCircuit conversion +/// and DagFaultAnalyzer see proper structured annotations. +fn build_tick_circuit(gates: &[Gate], meta: &CircuitMeasurementMeta) -> Option { + use pecos_quantum::{Attribute, TickMeasRef}; + + let mut tc = TickCircuit::default(); + let mut all_meas_refs: Vec = Vec::new(); + + for gate in gates { + match gate.gate_type { + GateType::MZ => { + // Use the typed .mz() API to properly track measurement records + let qubits: Vec = gate.qubits.iter().copied().collect(); + let refs = tc.tick().mz(&qubits); + all_meas_refs.extend(refs); + } + GateType::PZ | GateType::QAlloc => { + let qubits: Vec = gate.qubits.iter().copied().collect(); + tc.tick().pz(&qubits); + } + _ => { + let mut tick = tc.tick(); + let _ = tick.try_add_gate(gate.clone()); + } + } + } + + // Create detector annotations from record definitions + for records in &meta.detector_records { + let det_refs: Vec = records + .iter() + .filter_map(|&rec| { + let abs_idx = (meta.num_measurements as i32 + rec) as usize; + all_meas_refs.get(abs_idx).copied() + }) + .collect(); + if !det_refs.is_empty() { + tc.detector(&det_refs); + } + } + + // Create observable annotations from record definitions + for records in &meta.observable_records { + let obs_refs: Vec = records + .iter() + .filter_map(|&rec| { + let abs_idx = (meta.num_measurements as i32 + rec) as usize; + all_meas_refs.get(abs_idx).copied() + }) + .collect(); + if !obs_refs.is_empty() { + tc.observable(&obs_refs); + } + } + + // Set metadata (for DemBuilder JSON fallback path) + tc.set_meta( + "num_measurements", + Attribute::String(meta.num_measurements.to_string()), + ); + if let Ok(det_json) = serde_json::to_string( + &meta + .detector_records + .iter() + .enumerate() + .map(|(id, recs)| serde_json::json!({"id": id, "records": recs})) + .collect::>(), + ) { + tc.set_meta("detectors", Attribute::String(det_json)); + } + if let Ok(obs_json) = serde_json::to_string( + &meta + .observable_records + .iter() + .enumerate() + .map(|(id, recs)| serde_json::json!({"id": id, "records": recs})) + .collect::>(), + ) { + tc.set_meta("observables", Attribute::String(obs_json)); + } + + Some(tc) +} + +/// EEG path: DEM generation + ParsedDem sampling + measurement synthesis. +/// +/// Used when coherent noise (idle_rz) is present and the stochastic path +/// cannot capture the noise accurately. +fn run_eeg_path( + gates: &[Gate], + noise: &UniformNoise, + meta: &CircuitMeasurementMeta, + generator: &dyn DemGenerator, + shots: usize, + seed: u64, +) -> DemSimulationResult { + // Expand circuit for EEG analysis + let expanded = crate::expand::expand_circuit(gates); + let gate_index = GateIndex::build(&expanded.gates, expanded.num_qubits); + + // Build detectors and observables from metadata + let detectors = build_detectors_from_meta(meta, &expanded); + let observables = build_observables_from_meta(meta, &expanded); + + // Generate DEM via trait + let ctx = DemContext { + gates: &expanded.gates, + expanded: &expanded, + gate_index: &gate_index, + detectors: &detectors, + observables: &observables, + }; + let output = generator.generate(&ctx, noise); + let dem_str = crate::dem_mapping::format_dem(&output.entries); + + // Parse DEM and build sampler + let parsed_dem: ParsedDem = dem_str.parse().unwrap_or_else(|_| ParsedDem::new()); + let sampler = parsed_dem.to_dem_sampler(); + + // Build measurement synthesis info + let synthesis_info = MeasurementSynthesisInfo::build(meta, &expanded); + + // Sample and synthesize + let mut rng = PecosRng::seed_from_u64(seed); + let mut measurements = Vec::with_capacity(shots); + + for _ in 0..shots { + let (det_events, obs_flips) = sampler.sample(&mut rng); + let meas = synthesis_info.synthesize(&det_events, &obs_flips, &mut rng); + measurements.push(meas); + } + + DemSimulationResult { measurements } +} + +/// Build EEG Detector structs from circuit metadata. +fn build_detectors_from_meta( + meta: &CircuitMeasurementMeta, + expanded: &ExpandedCircuit, +) -> Vec { + meta.detector_records + .iter() + .enumerate() + .map(|(id, records)| { + let mut bm = crate::Bm::default(); + for &rec in records { + let meas_idx = (meta.num_measurements as i32 + rec) as usize; + if meas_idx < expanded.measurement_qubit.len() { + let q = expanded.measurement_qubit[meas_idx]; + bm.z_bits.set_bit(q); + } + } + crate::dem_mapping::Detector { id, stabilizer: bm } + }) + .collect() +} + +/// Build EEG Observable structs from circuit metadata. +fn build_observables_from_meta( + meta: &CircuitMeasurementMeta, + expanded: &ExpandedCircuit, +) -> Vec { + meta.observable_records + .iter() + .enumerate() + .map(|(id, records)| { + let mut bm = crate::Bm::default(); + for &rec in records { + let meas_idx = (meta.num_measurements as i32 + rec) as usize; + if meas_idx < expanded.measurement_qubit.len() { + let q = expanded.measurement_qubit[meas_idx]; + bm.z_bits.set_bit(q); + } + } + crate::dem_mapping::Observable { id, pauli: bm } + }) + .collect() +} + +/// Precomputed info for synthesizing measurements from detection events. +struct MeasurementSynthesisInfo { + num_meas: usize, + /// For each measurement: Some((det_idx, other_meas_idx)) if determined by a detector. + /// other_meas_idx == usize::MAX means single-record detector. + meas_info: Vec>, + /// Which measurements are non-deterministic (need random coin). + is_non_det: Vec, + /// Observable measurement assignments: (meas_idx, obs_idx). + obs_meas_info: Vec<(usize, usize)>, +} + +impl MeasurementSynthesisInfo { + /// Build synthesis info from circuit metadata. + fn build(meta: &CircuitMeasurementMeta, _expanded: &ExpandedCircuit) -> Self { + let num_meas = meta.num_measurements; + let mut meas_info: Vec> = vec![None; num_meas]; + + // Build detector -> measurement mapping + for (det_idx, records) in meta.detector_records.iter().enumerate() { + let abs_records: Vec = records + .iter() + .map(|&r| (num_meas as i32 + r) as usize) + .filter(|&idx| idx < num_meas) + .collect(); + + if abs_records.len() == 2 { + let (earlier, later) = if abs_records[0] < abs_records[1] { + (abs_records[0], abs_records[1]) + } else { + (abs_records[1], abs_records[0]) + }; + if meas_info[later].is_none() { + meas_info[later] = Some((det_idx, earlier)); + } + } else if abs_records.len() == 1 { + let idx = abs_records[0]; + if meas_info[idx].is_none() { + meas_info[idx] = Some((det_idx, usize::MAX)); + } + } + } + + // Identify non-deterministic measurements + let mut is_non_det = vec![false; num_meas]; + for idx in 0..num_meas { + if meas_info[idx].is_none() { + is_non_det[idx] = true; + } + } + // Also: measurements referenced as "other" by a detector but not assigned themselves + for idx in 0..num_meas { + if let Some((_, other_idx)) = meas_info[idx] { + if other_idx != usize::MAX && other_idx < num_meas && meas_info[other_idx].is_none() + { + is_non_det[other_idx] = true; + } + } + } + + // Observable measurement assignments + let mut obs_meas_info = Vec::new(); + for (obs_idx, records) in meta.observable_records.iter().enumerate() { + for &rec in records { + let idx = (num_meas as i32 + rec) as usize; + if idx < num_meas { + obs_meas_info.push((idx, obs_idx)); + } + } + } + + Self { + num_meas, + meas_info, + is_non_det, + obs_meas_info, + } + } + + /// Synthesize a measurement bitstring from detection events + observable flips. + fn synthesize(&self, det_events: &[bool], obs_flips: &[bool], rng: &mut PecosRng) -> Vec { + let mut meas = vec![0u8; self.num_meas]; + + // Random coins for non-deterministic measurements + for idx in 0..self.num_meas { + if self.is_non_det[idx] { + meas[idx] = if rng.random_bool(0.5) { 1 } else { 0 }; + } + } + + // Assign measurements in index order (time order) + for idx in 0..self.num_meas { + if let Some((det_idx, other_idx)) = self.meas_info[idx] { + if det_idx < det_events.len() && det_events[det_idx] { + if other_idx == usize::MAX { + meas[idx] ^= 1; + } else if other_idx < self.num_meas { + meas[idx] = u8::from(det_events[det_idx]) ^ meas[other_idx]; + } + } else if other_idx != usize::MAX && other_idx < self.num_meas { + meas[idx] = meas[other_idx]; + } + } + } + + // Apply observable flips + for &(meas_idx, obs_idx) in &self.obs_meas_info { + if obs_idx < obs_flips.len() && obs_flips[obs_idx] { + meas[meas_idx] ^= 1; + } + } + + meas + } +} diff --git a/exp/pecos-eeg/src/eeg.rs b/exp/pecos-eeg/src/eeg.rs new file mode 100644 index 000000000..1f342f747 --- /dev/null +++ b/exp/pecos-eeg/src/eeg.rs @@ -0,0 +1,120 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! EEG types: generator kinds and accumulators. + +use crate::Bm; +use std::collections::BTreeMap; + +/// The four types of Elementary Error Generators. +#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)] +pub enum EegType { + /// Hamiltonian: H_P[rho] = -i[P, rho]. Coherent rotations. + H, + /// Stochastic: S_P[rho] = P rho P - rho. Pauli errors. + S, + /// Correlation: C_{P,Q}. Two-Pauli correlations. + C, + /// Active: A_{P,Q}. Phase-dependent interference. + A, +} + +/// A single Elementary Error Generator with coefficient. +#[derive(Clone, Debug)] +pub struct Eeg { + pub eeg_type: EegType, + pub label_p: Bm, + pub label_q: Bm, + pub coeff: f64, +} + +/// Accumulator for Hamiltonian EEGs (H_P type). +/// +/// Stores the sum of coefficients for each Pauli label. This is the +/// first-order BCH result: G_c = Sigma epsilon_P H_P. +#[derive(Clone, Debug, Default)] +pub struct HamiltonianAccumulator { + generators: BTreeMap, +} + +impl HamiltonianAccumulator { + #[must_use] + pub fn new() -> Self { + Self::default() + } + + /// Add H_P with coefficient epsilon. + /// Accumulates (first-order BCH = sum). + pub fn add(&mut self, label: Bm, coeff: f64) { + *self.generators.entry(label).or_insert(0.0) += coeff; + } + + #[must_use] + pub fn len(&self) -> usize { + self.generators.len() + } + + #[must_use] + pub fn is_empty(&self) -> bool { + self.generators.is_empty() + } + + pub fn iter(&self) -> impl Iterator { + self.generators.iter() + } + + pub fn prune(&mut self, threshold: f64) { + self.generators.retain(|_, c| c.abs() > threshold); + } +} + +/// Accumulator for Stochastic EEGs (S_P type). +/// +/// S-type generators commute, so first-order BCH is exact. +#[derive(Clone, Debug, Default)] +pub struct StochasticAccumulator { + generators: BTreeMap, +} + +impl StochasticAccumulator { + #[must_use] + pub fn new() -> Self { + Self::default() + } + + pub fn add(&mut self, label: Bm, coeff: f64) { + *self.generators.entry(label).or_insert(0.0) += coeff; + } + + #[must_use] + pub fn len(&self) -> usize { + self.generators.len() + } + + #[must_use] + pub fn is_empty(&self) -> bool { + self.generators.is_empty() + } + + pub fn iter(&self) -> impl Iterator { + self.generators.iter() + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_hamiltonian_accumulator() { + let mut acc = HamiltonianAccumulator::new(); + acc.add(Bm::z(0), 0.05); + acc.add(Bm::z(0), 0.03); + acc.add(Bm::x(1), 0.02); + + assert_eq!(acc.len(), 2); + let z0 = acc.generators.get(&Bm::z(0)).unwrap(); + assert!((z0 - 0.08).abs() < 1e-10); + } +} diff --git a/exp/pecos-eeg/src/expand.rs b/exp/pecos-eeg/src/expand.rs new file mode 100644 index 000000000..6d3ec5278 --- /dev/null +++ b/exp/pecos-eeg/src/expand.rs @@ -0,0 +1,447 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Deferred measurement: expand a circuit by replacing mid-circuit +//! MZ+PZ with CX to auxiliary qubits, deferring all measurements to the end. +//! +//! After expansion, the circuit is purely Clifford (no mid-circuit +//! measurements), and error generators can be propagated straight through. + +use crate::Bm; +use pecos_core::gate_type::GateType; +use pecos_core::pauli::pauli_bitmask::BitmaskStorage; +use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; + +/// Result of circuit expansion. +pub struct ExpandedCircuit { + /// The expanded gate sequence (purely Clifford, no mid-circuit measurements). + pub gates: Vec, + /// Total number of qubits (original + auxiliary). + pub num_qubits: usize, + /// Number of original qubits. + pub num_original_qubits: usize, + /// Mapping: measurement record index → auxiliary qubit index. + /// measurement_qubit[k] = the auxiliary qubit whose Z-measurement at + /// the end gives the k-th measurement record. + pub measurement_qubit: Vec, + /// Mapping: measurement record index → original qubit that was measured. + /// original_measured_qubit[k] = the qubit in the original circuit that + /// the k-th MZ gate acted on. + pub original_measured_qubit: Vec, +} + +/// Expand a circuit by deferring mid-circuit measurements. +/// +/// For each MZ(q) followed by PZ(q), replaces with: +/// 1. CX(q, aux) — copy q's state to a fresh auxiliary qubit +/// 2. PZ(q) — reset q to |0> (kept as-is, since PZ after CX is valid) +/// +/// All auxiliary qubits are measured at the end via MZ. +/// Final data measurements (MZ not followed by PZ) are also deferred +/// to auxiliary qubits for uniformity. +pub fn expand_circuit(gates: &[Gate]) -> ExpandedCircuit { + // First pass: find the max qubit index to know where auxiliaries start + let max_qubit = gates + .iter() + .flat_map(|g| g.qubits.iter()) + .map(|q| q.index()) + .max() + .unwrap_or(0); + let num_original = max_qubit + 1; + let mut next_aux = num_original; + + let mut expanded = Vec::with_capacity(gates.len() * 2); + let mut measurement_qubit = Vec::new(); + let mut original_measured_qubit = Vec::new(); + + // Identify which MZ gates are mid-circuit (followed by PZ on same qubit) + // vs final (not followed by any operation on that qubit, or followed by + // a different operation). + // + // Track ancilla qubits: those with a PZ after the first non-PZ gate. + // Only ancilla MZ gets a post-expansion PZ (measurement projection). + let mut ancilla_qubits = std::collections::HashSet::new(); + { + let mut past_init = false; + for g in gates { + if past_init && (g.gate_type == GateType::PZ || g.gate_type == GateType::QAlloc) { + for q in &g.qubits { + ancilla_qubits.insert(q.index()); + } + } + if g.gate_type != GateType::PZ && g.gate_type != GateType::QAlloc { + past_init = true; + } + } + } + + // Strategy: walk gates, when we see MZ(q): + // - Replace with CX(q, aux_new) where aux_new is a fresh auxiliary + // - For ancilla qubits: add PZ(q) to model measurement projection + // - Record that measurement k maps to aux_new + // - The auxiliary qubit is measured at the end + + let mut i = 0; + while i < gates.len() { + let gate = &gates[i]; + + match gate.gate_type { + GateType::MZ => { + // For each qubit in this MZ gate, create CX to auxiliary + for q in &gate.qubits { + let q_idx = q.index(); + let aux = next_aux; + next_aux += 1; + + // Initialize auxiliary: QAlloc(aux) + // Use QAlloc (not PZ) so the noise model can distinguish + // auxiliary initialization from original circuit resets. + expanded.push(make_gate(GateType::QAlloc, &[aux])); + + // CX(q, aux) — copy measurement info to auxiliary + expanded.push(make_gate(GateType::CX, &[q_idx, aux])); + + // For ancilla qubits: add PZ to model measurement projection. + // MZ projects to a Z eigenstate, destroying X/Y coherences. + // Without this, the last round's syndrome generators retain + // X on the measured ancilla, creating spurious correlations. + // For intermediate rounds this is redundant (circuit PZ follows). + // + // Data readout MZ does NOT get PZ: data qubit Z components + // must persist for correct generator labels (Z errors are + // invisible to Z-basis readout and must not be cleared). + if ancilla_qubits.contains(&q_idx) { + expanded.push(make_gate(GateType::PZ, &[q_idx])); + } + + // Record: this measurement maps to the auxiliary qubit + measurement_qubit.push(aux); + original_measured_qubit.push(q_idx); + } + } + GateType::PZ | GateType::QAlloc => { + // Keep resets — they re-initialize the qubit for the next round + expanded.push(gate.clone()); + } + _ => { + // All other gates pass through unchanged + expanded.push(gate.clone()); + } + } + + i += 1; + } + + // Add final measurements of all auxiliary qubits at the end + for &aux in &measurement_qubit { + expanded.push(make_gate(GateType::MZ, &[aux])); + } + + ExpandedCircuit { + gates: expanded, + num_qubits: next_aux, + num_original_qubits: num_original, + measurement_qubit, + original_measured_qubit, + } +} + +impl ExpandedCircuit { + /// Map an expanded-circuit Pauli back to the original circuit frame. + /// + /// X on auxiliary qubit `aux_k` → X on `original_measured_qubit[k]` + /// (because `CX(q, aux)` copies X from control to target: X on aux + /// in the expanded circuit corresponds to X on q in the original). + /// + /// Z on auxiliary qubits is dropped (doesn't correspond to original). + /// Components on original qubits pass through unchanged. + pub fn map_to_original_frame(&self, p: &Bm) -> Bm { + let mut result = Bm::default(); + + // Copy components on original qubits directly + for q in 0..self.num_original_qubits { + if p.has_x(q) { + result.x_bits.set_bit(q); + } + if p.has_z(q) { + result.z_bits.set_bit(q); + } + } + + // Map X on auxiliary qubits to X on original measured qubits + for (meas_idx, &aux_q) in self.measurement_qubit.iter().enumerate() { + if p.has_x(aux_q) { + let orig_q = self.original_measured_qubit[meas_idx]; + result.x_bits.xor_bit(orig_q); // XOR because same qubit may be measured multiple times + } + // Z on aux is ignored (measurement projection absorbs Z) + } + + result + } +} + +/// Precomputed qubit-to-gate index for sparse backward traversal. +/// +/// For each qubit, stores the gate indices (in the flat gate list) that +/// touch it, sorted in ascending order. This enables the backward walk +/// to visit only gates on active qubits instead of scanning all gates. +pub struct GateIndex { + /// qubit_gates[q] = sorted Vec of gate indices touching qubit q. + qubit_gates: Vec>, + /// Which gates are expansion gates (no physical noise). + pub expansion_gates: Vec, +} + +impl GateIndex { + /// Build the index from a gate list (typically the expanded circuit). + pub fn build(gates: &[Gate], num_qubits: usize) -> Self { + let mut qubit_gates = vec![Vec::new(); num_qubits]; + + for (i, gate) in gates.iter().enumerate() { + for q in &gate.qubits { + qubit_gates[q.index()].push(i as u32); + } + } + + // Identify expansion gates (QAlloc + subsequent CX + PZ) + let mut expansion = vec![false; gates.len()]; + for i in 0..gates.len() { + if gates[i].gate_type == GateType::QAlloc { + expansion[i] = true; + } + } + for i in 1..gates.len() { + if gates[i].gate_type == GateType::CX && gates[i - 1].gate_type == GateType::QAlloc { + let alloc_q = gates[i - 1].qubits[0].index(); + if gates[i].qubits.len() >= 2 && gates[i].qubits[1].index() == alloc_q { + expansion[i] = true; + if i + 1 < gates.len() + && gates[i + 1].gate_type == GateType::PZ + && gates[i + 1].qubits[0].index() == gates[i].qubits[0].index() + { + expansion[i + 1] = true; + } + } + } + } + + Self { qubit_gates, expansion_gates: expansion } + } + + /// Gate indices touching qubit `q` in reverse order (for backward walk). + pub fn gates_on_qubit_rev(&self, q: usize) -> impl Iterator + '_ { + self.qubit_gates.get(q).into_iter().flat_map(|v| v.iter().copied().rev()) + } + + /// Is this gate an expansion gate (no physical noise)? + #[inline] + pub fn is_expansion(&self, gate_idx: usize) -> bool { + self.expansion_gates.get(gate_idx).copied().unwrap_or(false) + } +} + +pub fn make_gate(gt: GateType, qubits: &[usize]) -> Gate { + Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), + } +} + +#[cfg(test)] +mod tests { + use super::*; + + fn gate(gt: GateType, qubits: &[usize]) -> Gate { + make_gate(gt, qubits) + } + + #[test] + fn test_expand_simple_mcm() { + // PZ(0), H(0), MZ(0), PZ(0), H(0), MZ(0) + // Two rounds: measure, reset, measure again + let gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::H, &[0]), + gate(GateType::MZ, &[0]), // → CX(0, aux0) + gate(GateType::PZ, &[0]), // reset + gate(GateType::H, &[0]), + gate(GateType::MZ, &[0]), // → CX(0, aux1) + ]; + + let expanded = expand_circuit(&gates); + + // Should have 3 qubits: original 0, aux 1, aux 2 + assert_eq!(expanded.num_original_qubits, 1); + assert_eq!(expanded.num_qubits, 3); + assert_eq!(expanded.measurement_qubit.len(), 2); + + // No MZ in the middle — only at the end + let mid_mz = expanded.gates[..expanded.gates.len() - 2] + .iter() + .filter(|g| g.gate_type == GateType::MZ) + .count(); + assert_eq!(mid_mz, 0, "No mid-circuit MZ in expanded circuit"); + + // Two MZ at the end (one per auxiliary) + let end_mz = expanded.gates.iter() + .rev() + .take_while(|g| g.gate_type == GateType::MZ) + .count(); + assert_eq!(end_mz, 2); + } + + #[test] + fn test_expand_preserves_cliffords() { + let gates = vec![ + gate(GateType::PZ, &[0, 1]), + gate(GateType::H, &[0]), + gate(GateType::CX, &[0, 1]), + ]; + + let expanded = expand_circuit(&gates); + + // No measurements → no expansion needed + assert_eq!(expanded.num_qubits, 2); + assert_eq!(expanded.measurement_qubit.len(), 0); + assert_eq!(expanded.gates.len(), 3); // same gates + } + + #[test] + fn test_measurement_qubit_mapping() { + // 2 qubits, measure both + let gates = vec![ + gate(GateType::PZ, &[0, 1]), + gate(GateType::H, &[0]), + gate(GateType::CX, &[0, 1]), + gate(GateType::MZ, &[0]), // meas record 0 → aux 2 + gate(GateType::MZ, &[1]), // meas record 1 → aux 3 + ]; + + let expanded = expand_circuit(&gates); + + assert_eq!(expanded.measurement_qubit, vec![2, 3]); + assert_eq!(expanded.num_qubits, 4); + } + + #[test] + fn test_map_to_original_frame_x_on_aux() { + // X on auxiliary → X on original measured qubit + let gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::MZ, &[0]), // meas 0 → aux 1 + ]; + let expanded = expand_circuit(&gates); + + // X on aux 1 maps to X on original qubit 0 + let p = Bm::x(1); // aux qubit + let mapped = expanded.map_to_original_frame(&p); + assert_eq!(mapped, Bm::x(0)); + } + + #[test] + fn test_map_to_original_frame_z_on_aux_dropped() { + // Z on auxiliary is dropped (measurement projection absorbs it) + let gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::MZ, &[0]), + ]; + let expanded = expand_circuit(&gates); + + let p = Bm::z(1); // Z on aux + let mapped = expanded.map_to_original_frame(&p); + assert!(mapped.is_identity(), "Z on aux should be dropped"); + } + + #[test] + fn test_map_to_original_frame_original_passthrough() { + // Components on original qubits pass through unchanged + let gates = vec![ + gate(GateType::PZ, &[0, 1]), + gate(GateType::MZ, &[0]), + ]; + let expanded = expand_circuit(&gates); + + let p = Bm::x(0).multiply(&Bm::z(1)); // X0 Z1 + let mapped = expanded.map_to_original_frame(&p); + assert_eq!(mapped, Bm::x(0).multiply(&Bm::z(1))); + } + + #[test] + fn test_expand_final_only_mz() { + // Circuit with only final MZ (no mid-circuit measurement) + let gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::H, &[0]), + gate(GateType::MZ, &[0]), + ]; + let expanded = expand_circuit(&gates); + + // Still creates one aux qubit for the final MZ + assert_eq!(expanded.num_qubits, 2); + assert_eq!(expanded.measurement_qubit.len(), 1); + } + + #[test] + fn test_expansion_pz_for_ancilla_mz() { + // Circuit: PZ(0,1), H(1), CX(1,0), MZ(1), PZ(1), H(1), CX(1,0), MZ(1), MZ(0) + // Qubit 1 is ancilla (has mid-circuit PZ). Qubit 0 is data. + // Last-round MZ(1) should get expansion PZ(1). + // Final MZ(0) should NOT get expansion PZ. + let gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::H, &[1]), + gate(GateType::CX, &[1, 0]), + gate(GateType::MZ, &[1]), // round 1 syndrome + gate(GateType::PZ, &[1]), // reset + gate(GateType::H, &[1]), + gate(GateType::CX, &[1, 0]), + gate(GateType::MZ, &[1]), // round 2 syndrome (last round, no PZ after) + gate(GateType::MZ, &[0]), // data readout + ]; + + let expanded = expand_circuit(&gates); + + // Count PZ/QAlloc gates on qubit 1 in the expanded circuit + let resets_on_1: Vec<_> = expanded.gates.iter() + .filter(|g| (g.gate_type == GateType::PZ || g.gate_type == GateType::QAlloc) + && g.qubits.iter().any(|q| q.index() == 1)) + .collect(); + + // Should have: original PZ(1) init + expansion PZ(1) round 1 + circuit PZ(1) reset + // + expansion PZ(1) round 2 = 4 reset gates on qubit 1 + eprintln!("Resets on qubit 1: {} gates", resets_on_1.len()); + assert!(resets_on_1.len() >= 4, + "Should have expansion PZ for last-round MZ(1): got {} on q1", + resets_on_1.len()); + + // Count resets on qubit 0 in expanded circuit + let resets_on_0: Vec<_> = expanded.gates.iter() + .filter(|g| (g.gate_type == GateType::PZ || g.gate_type == GateType::QAlloc) + && g.qubits.iter().any(|q| q.index() == 0)) + .collect(); + // Should have only: original PZ(0) init = 1 + eprintln!("Resets on qubit 0: {} gates", resets_on_0.len()); + assert_eq!(resets_on_0.len(), 1, "Data qubit should NOT get expansion PZ"); + } + + #[test] + fn test_expand_multi_round_tracks_original_qubits() { + // Two rounds measuring qubit 0: both aux should map back to qubit 0 + let gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::MZ, &[0]), + gate(GateType::PZ, &[0]), + gate(GateType::MZ, &[0]), + ]; + let expanded = expand_circuit(&gates); + + assert_eq!(expanded.measurement_qubit.len(), 2); + assert_eq!(expanded.original_measured_qubit, vec![0, 0]); + } +} diff --git a/exp/pecos-eeg/src/heisenberg.rs b/exp/pecos-eeg/src/heisenberg.rs new file mode 100644 index 000000000..2bed94bf7 --- /dev/null +++ b/exp/pecos-eeg/src/heisenberg.rs @@ -0,0 +1,2374 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Backward Heisenberg propagation of detectors through noise. +//! +//! Computes exact detection probabilities by propagating the detector +//! observable BACKWARD through the expanded (measurement-deferred) circuit. +//! +//! Coherent (H-type) noise: at each source exp(h·H_P), the observable +//! transforms via unitary conjugation: +//! D → cos(2h)·D + i·sin(2h)·P·D (when D and P anticommute) +//! D → D (when D and P commute) +//! +//! Stochastic (S-type) noise: EEG rate s < 0, physical error +//! probability p = (1/2)(1 - exp(2s)). Heisenberg dual: +//! D → D (when D and P commute) +//! D → exp(2s)·D (when D and P anticommute) +//! +//! The cost is exponential in the number of anticommuting H-type noise +//! sources per detector (2^m terms), but this is typically manageable +//! for QEC circuits (m ~ 5-15). S-type noise does not increase term count. +//! +//! Both a Pauli-tracking walk (fast, exact) and a matrix-based method +//! (exact, limited to ~20 qubits) are provided. + +use crate::Bm; +use crate::noise::NoiseSpec; +use crate::stabilizer::StabilizerGroup; +use pecos_core::gate_type::GateType; +use pecos_core::pauli::pauli_bitmask::*; +use pecos_core::Gate; +use smallvec::SmallVec; + +/// Precomputed noise for a single gate: H-type injections + batched S-type scale. +/// +/// Instead of calling `noise_after_gate()` during the walk and processing +/// 15+ S-type injections individually, we precompute: +/// - H-type injections (kept as-is, they cause branching) +/// - A combined S-type scale factor per qubit-support pattern +/// +/// For uniform 2-qubit depolarizing at rate p: any term with non-identity +/// on either gate qubit gets scaled by `(1-2p/15)^8` (exactly 8 of 15 +/// Paulis anticommute for any non-identity support). Single-qubit: `(1-2p/3)^2`. +pub struct PrecomputedGateNoise { + /// H-type injections (cause term branching, can't be batched). + pub h_injections: SmallVec<[crate::noise::NoiseInjection; 2]>, + /// Combined S-type scale for terms with non-identity on qubit 0 only. + /// (For 1q gates, this is the full scale. For 2q, see q1_scale/both_scale.) + pub q0_scale: f64, + /// Qubit 0 index (for S-type fast path). + pub q0: u16, + /// Combined S-type scale for terms with non-identity on qubit 1 only (2q gates). + pub q1_scale: f64, + /// Qubit 1 index. + pub q1: u16, + /// Combined S-type scale for terms with non-identity on BOTH qubits. + pub both_scale: f64, + /// Number of qubits this gate acts on (0, 1, or 2). + pub num_gate_qubits: u8, +} + +/// Build a noise map: precomputed noise for each gate. +/// +/// Returns `None` for gates with no noise. Expansion gates are mostly +/// skipped, except expansion CX gates get p_meas noise on their control +/// qubit (the originally-measured qubit) to model mid-circuit measurement +/// errors that the expansion would otherwise lose. +pub fn build_noise_map( + gates: &[Gate], + noise: &dyn NoiseSpec, + expansion_gates: &[bool], +) -> Vec> { + let mut map = Vec::with_capacity(gates.len()); + + for (i, gate) in gates.iter().enumerate() { + if i < expansion_gates.len() && expansion_gates[i] { + map.push(None); + continue; + } + + let qubits: SmallVec<[usize; 4]> = gate.qubits.iter() + .map(|q| q.index()).collect(); + let injections = noise.noise_after_gate(i, gate.gate_type, &qubits); + + if injections.is_empty() { + map.push(None); + continue; + } + + let mut h_inj = SmallVec::new(); + // Collect S-type rates grouped by which qubits they touch. + // We compute a combined scale factor for each support pattern. + let mut s_rates_q0_only = Vec::new(); // S noise on q0 only + let mut s_rates_q1_only = Vec::new(); // S noise on q1 only + let mut s_rates_both = Vec::new(); // S noise on both q0 and q1 + let mut s_rates_other = Vec::new(); // S noise on other patterns + + let q0 = qubits.first().copied().unwrap_or(0) as u16; + let q1 = if qubits.len() >= 2 { qubits[1] as u16 } else { q0 }; + + for inj in &injections { + match inj.eeg_type { + crate::eeg::EegType::H => { h_inj.push(inj.clone()); } + crate::eeg::EegType::S => { + let rate = inj.rate; + // Classify by qubit support + let on_q0 = inj.label.has_x(q0 as usize) || inj.label.has_z(q0 as usize); + let on_q1 = qubits.len() >= 2 + && (inj.label.has_x(q1 as usize) || inj.label.has_z(q1 as usize)); + + // For each S injection with rate s (s < 0), the scale for + // anticommuting terms is (1 - 2*(-s)) = (1 + 2s). + // We need to count how many of the term's components + // anticommute. For a uniform depolarizing model this is + // predetermined by the support pattern. + // + // Instead of trying to batch analytically (which requires + // knowing the exact anticommutation count), we accumulate + // the log of the scale factors and compute the combined + // scale per support pattern. + // + // For now, just collect individual rates. + if on_q0 && !on_q1 { s_rates_q0_only.push(rate); } + else if !on_q0 && on_q1 { s_rates_q1_only.push(rate); } + else if on_q0 && on_q1 { s_rates_both.push(rate); } + else { s_rates_other.push(rate); } + } + _ => { h_inj.push(inj.clone()); } + } + } + + // Compute combined scale factors. + // A term anticommutes with S_P iff it has non-trivial overlap with P. + // + // For a term with non-identity on q0 only: + // - Anticommutes with S generators touching q0: all of q0_only + both + // - But WHICH ones anticommute depends on the specific Pauli. + // + // For uniform depolarizing, the count of anticommuting generators is + // deterministic given the support pattern. But for general S noise, we + // can't batch — fall back to individual processing. + // + // Optimization: if ALL S rates are the same (uniform depol), use + // closed-form. Otherwise, keep individual injections. + let all_s_same_rate = { + let all_s: Vec = s_rates_q0_only.iter() + .chain(&s_rates_q1_only) + .chain(&s_rates_both) + .chain(&s_rates_other) + .copied().collect(); + !all_s.is_empty() && all_s.iter().all(|&r| (r - all_s[0]).abs() < 1e-20) + }; + + if all_s_same_rate && s_rates_other.is_empty() { + // Uniform depolarizing: use closed-form combined scale. + // For any non-identity on q0: 2 of {X,Y,Z} on q0 anticommute. + // For single-qubit: 3 S generators, 2 anticommute → scale = (1+2s)^2 + // For two-qubit: 15 S generators, 8 anticommute for any non-trivial → (1+2s)^8 + let total_s = s_rates_q0_only.len() + s_rates_q1_only.len() + s_rates_both.len(); + let s = s_rates_q0_only.first() + .or(s_rates_q1_only.first()) + .or(s_rates_both.first()) + .copied().unwrap_or(0.0); + let p = -s; + let individual_scale = 1.0 - 2.0 * p; + + // Count anticommuting for each support pattern. + // For term with non-identity on q0 only: + // anti with q0-only S: 2 out of 3 (if 1q) or 2 out of 3 (for each A⊗I) + // anti with both S: depends on q1 part (commutes since term has I on q1) + // Total for 2q depol: q0_only anti=2 out of 3, both anti=q0 part anti * q1 commutes + // = 2*3 (from 3 A⊗I where 2 of 3 A anticommute on q0, B=I commutes) + // + 0 (from 3 I⊗B) + // + 2*3 (from 9 A⊗B where 2 of 3 A anticommute, B commutes since I on q1) + // Wait, {A, I_term} always commutes for B part. So: + // anti count = (anti on q0) * (total on q1 including I) + (comm on q0) * (anti on q1) + // For term I on q1: anti on q1 = 0. + // So anti count = 2 * 4 + 2 * 0 = 8 for 15 generators (excluding I⊗I). + // + // Actually, let me just precompute this properly. + // For 1q depol (3 generators): non-identity on q → 2 anticommute → (1-2p/3)^2 + // For 2q depol (15 generators): non-identity on either q → 8 anticommute → (1-2p/15)^8 + let n_anti = if total_s == 3 { 2 } else if total_s == 15 { 8 } else { 0 }; + if n_anti == 0 && total_s > 0 { + // Non-standard S count (e.g., 1 for p_meas, 1 for p_prep): + // can't batch — put in h_injections for individual processing. + for inj in &injections { + if inj.eeg_type == crate::eeg::EegType::S { + h_inj.push(inj.clone()); + } + } + } + let combined = individual_scale.powi(n_anti); + + map.push(Some(PrecomputedGateNoise { + h_injections: h_inj, + q0_scale: combined, + q0, + q1_scale: combined, + q1, + both_scale: combined, + num_gate_qubits: qubits.len().min(2) as u8, + })); + } else if s_rates_q0_only.is_empty() && s_rates_q1_only.is_empty() + && s_rates_both.is_empty() && s_rates_other.is_empty() + { + // H-type only, no S noise + if h_inj.is_empty() { + map.push(None); + } else { + map.push(Some(PrecomputedGateNoise { + h_injections: h_inj, + q0_scale: 1.0, q0, q1_scale: 1.0, q1, both_scale: 1.0, + num_gate_qubits: qubits.len().min(2) as u8, + })); + } + } else { + // Non-uniform S noise: keep individual injections as H-type + // (the walk handles them individually). + for inj in injections { + if inj.eeg_type == crate::eeg::EegType::S { + h_inj.push(inj); // process individually in walk + } + } + map.push(Some(PrecomputedGateNoise { + h_injections: h_inj, + q0_scale: 1.0, q0, q1_scale: 1.0, q1, both_scale: 1.0, + num_gate_qubits: qubits.len().min(2) as u8, + })); + } + } + + map +} + +/// Sparse Pauli: stores only qubits with non-identity Pauli. +/// For terms touching ~10-20 qubits out of 1000+, this is 10-100x +/// more compact than a dense bitmask, making clone/cmp/hash O(support). +/// +/// Stored as sorted lists of qubit indices for X and Z components. +/// Y on qubit q means q appears in BOTH x_qubits and z_qubits. +#[derive(Clone, Debug, Default)] +pub(crate) struct SparsePauli { + x_qubits: SmallVec<[u16; 16]>, + z_qubits: SmallVec<[u16; 16]>, +} + +impl SparsePauli { + pub(crate) fn from_bm(bm: &Bm) -> Self { + let mut sp = Self::default(); + let max_x = bm.x_bits.highest_set_bit().unwrap_or(0); + let max_z = bm.z_bits.highest_set_bit().unwrap_or(0); + let max_q = max_x.max(max_z); + for q in 0..=max_q { + if bm.has_x(q) { sp.x_qubits.push(q as u16); } + if bm.has_z(q) { sp.z_qubits.push(q as u16); } + } + sp + } + + pub(crate) fn to_bm(&self) -> Bm { + let mut bm = Bm::default(); + for &q in &self.x_qubits { bm.x_bits.set_bit(q as usize); } + for &q in &self.z_qubits { bm.z_bits.set_bit(q as usize); } + bm + } + + #[inline] + fn is_identity(&self) -> bool { + self.x_qubits.is_empty() && self.z_qubits.is_empty() + } + + #[inline] + fn has_x(&self, q: u16) -> bool { + self.x_qubits.binary_search(&q).is_ok() + } + + #[inline] + fn has_z(&self, q: u16) -> bool { + self.z_qubits.binary_search(&q).is_ok() + } + + /// Toggle x-bit at qubit q (insert if missing, remove if present). + fn toggle_x(&mut self, q: u16) { + match self.x_qubits.binary_search(&q) { + Ok(i) => { self.x_qubits.remove(i); } + Err(i) => { self.x_qubits.insert(i, q); } + } + } + + fn toggle_z(&mut self, q: u16) { + match self.z_qubits.binary_search(&q) { + Ok(i) => { self.z_qubits.remove(i); } + Err(i) => { self.z_qubits.insert(i, q); } + } + } + + /// Remove X at qubit q (for PZ backward: kill if has_x). + pub(crate) fn clear_x(&mut self, q: u16) { + if let Ok(i) = self.x_qubits.binary_search(&q) { + self.x_qubits.remove(i); + } + } + + pub(crate) fn clear_z(&mut self, q: u16) { + if let Ok(i) = self.z_qubits.binary_search(&q) { + self.z_qubits.remove(i); + } + } + + /// Check if this Pauli commutes with a single-qubit Z_q. + /// Full commutation check with another SparsePauli. + fn commutes_with(&self, other: &Self) -> bool { + // Symplectic inner product mod 2: + // count = |self.x ∩ other.z| + |self.z ∩ other.x| + // Commutes iff count is even. + let c1 = sorted_intersection_count(&self.x_qubits, &other.z_qubits); + let c2 = sorted_intersection_count(&self.z_qubits, &other.x_qubits); + (c1 + c2) % 2 == 0 + } +} + +impl PartialEq for SparsePauli { + fn eq(&self, other: &Self) -> bool { + self.x_qubits == other.x_qubits && self.z_qubits == other.z_qubits + } +} +impl Eq for SparsePauli {} + +impl std::hash::Hash for SparsePauli { + fn hash(&self, state: &mut H) { + self.x_qubits.as_slice().hash(state); + self.z_qubits.as_slice().hash(state); + } +} + +impl Ord for SparsePauli { + fn cmp(&self, other: &Self) -> std::cmp::Ordering { + self.x_qubits.as_slice().cmp(other.x_qubits.as_slice()) + .then(self.z_qubits.as_slice().cmp(other.z_qubits.as_slice())) + } +} +impl PartialOrd for SparsePauli { + fn partial_cmp(&self, other: &Self) -> Option { Some(self.cmp(other)) } +} + +/// Count elements in the intersection of two sorted slices. +#[inline] +fn sorted_intersection_count(a: &[u16], b: &[u16]) -> u32 { + let (mut i, mut j) = (0, 0); + let mut count = 0u32; + while i < a.len() && j < b.len() { + match a[i].cmp(&b[j]) { + std::cmp::Ordering::Less => i += 1, + std::cmp::Ordering::Greater => j += 1, + std::cmp::Ordering::Equal => { count += 1; i += 1; j += 1; } + } + } + count +} + +impl SparsePauli { + /// Conjugate by Hadamard on qubit q: X↔Z, Y→-Y. + fn conjugate_h(&mut self, q: u16) -> bool { + let hx = self.has_x(q); + let hz = self.has_z(q); + if hx != hz { + // X→Z or Z→X: swap + self.toggle_x(q); + self.toggle_z(q); + } + // Y→-Y: sign flip when both X and Z + hx && hz + } + + /// Conjugate by CX(control, target). Returns sign_negative. + fn conjugate_cx(&mut self, c: u16, t: u16) -> bool { + let cx = self.has_x(c); + let cz = self.has_z(c); + let tx = self.has_x(t); + let tz = self.has_z(t); + if cx { self.toggle_x(t); } + if tz { self.toggle_z(c); } + // Sign from phase table (same formula as the fixed conjugate_cx) + const PHASE: [[u8; 4]; 4] = [ + [0, 0, 0, 0], [0, 0, 3, 1], [0, 1, 0, 3], [0, 3, 1, 0], + ]; + let pc = (cx as u8) + 2 * (cz as u8); + let pt = (tx as u8) + 2 * (tz as u8); + let phase_c = if tz { PHASE[pc as usize][2] } else { 0 }; + let phase_t = if cx { PHASE[1][pt as usize] } else { 0 }; + (phase_c + phase_t) % 4 == 2 + } + + /// Conjugate by CZ(a, b). Returns sign_negative. + fn conjugate_cz(&mut self, a: u16, b: u16) -> bool { + let ax = self.has_x(a); + let bx = self.has_x(b); + let az = self.has_z(a); + let bz = self.has_z(b); + if bx { self.toggle_z(a); } + if ax { self.toggle_z(b); } + ax && bx && (az != bz) + } + + /// Conjugate by Pauli X on qubit q. + fn conjugate_pauli_x(&self, q: u16) -> bool { self.has_z(q) } + /// Conjugate by Pauli Y on qubit q. + fn conjugate_pauli_y(&self, q: u16) -> bool { self.has_x(q) != self.has_z(q) } + /// Conjugate by Pauli Z on qubit q. + fn conjugate_pauli_z(&self, q: u16) -> bool { self.has_x(q) } + + /// Conjugate by SZ on qubit q: X→Y, Y→-X, Z→Z. + fn conjugate_sz(&mut self, q: u16) -> bool { + if !self.has_x(q) { return false; } + let was_y = self.has_z(q); + self.toggle_z(q); + was_y + } + + /// Conjugate by SZdg on qubit q. + fn conjugate_szdg(&mut self, q: u16) -> bool { + if !self.has_x(q) { return false; } + let was_y = self.has_z(q); + self.toggle_z(q); + !was_y + } + + /// Conjugate by SX on qubit q. + fn conjugate_sx(&mut self, q: u16) -> bool { + let xq = self.has_x(q); + let zq = self.has_z(q); + if zq { self.toggle_x(q); } + !xq && zq + } + + /// Conjugate by SXdg on qubit q. + fn conjugate_sxdg(&mut self, q: u16) -> bool { + let xq = self.has_x(q); + let zq = self.has_z(q); + if zq { self.toggle_x(q); } + xq && zq + } + + /// Conjugate by SY on qubit q. + fn conjugate_sy(&mut self, q: u16) -> bool { + let xq = self.has_x(q); + let zq = self.has_z(q); + if xq != zq { + self.toggle_x(q); + self.toggle_z(q); + } + xq && !zq + } + + /// Conjugate by SYdg on qubit q. + fn conjugate_sydg(&mut self, q: u16) -> bool { + let xq = self.has_x(q); + let zq = self.has_z(q); + if xq != zq { + self.toggle_x(q); + self.toggle_z(q); + } + !xq && zq + } + + /// Conjugate by SWAP(a, b). + fn conjugate_swap(&mut self, a: u16, b: u16) { + let ax = self.has_x(a); let az = self.has_z(a); + let bx = self.has_x(b); let bz = self.has_z(b); + // Clear both + if ax { self.clear_x(a); } if az { self.clear_z(a); } + if bx { self.clear_x(b); } if bz { self.clear_z(b); } + // Set swapped + if bx { self.toggle_x(a); } if bz { self.toggle_z(a); } + if ax { self.toggle_x(b); } if az { self.toggle_z(b); } + } +} + +/// Apply backward (Heisenberg) gate conjugation: P → U† P U. +/// +/// The conjugation methods on `SparsePauli` use the Schrödinger convention +/// (P → U P U†), so for the backward walk we swap non-self-adjoint gates +/// to their adjoints: SZ↔SZdg, SX↔SXdg, SY↔SYdg, SZZ↔SZZdg, etc. +/// Self-adjoint gates (H, X, Y, Z, CX, CZ, SWAP, CY) are unchanged. +pub(crate) fn sparse_conjugate(p: &mut SparsePauli, gate: &Gate) -> Option { + if gate.qubits.is_empty() { return None; } + let q0 = gate.qubits[0].index() as u16; + match gate.gate_type { + // Self-adjoint single-qubit gates + GateType::H => Some(p.conjugate_h(q0)), + GateType::X => Some(p.conjugate_pauli_x(q0)), + GateType::Y => Some(p.conjugate_pauli_y(q0)), + GateType::Z => Some(p.conjugate_pauli_z(q0)), + // Non-self-adjoint single-qubit: swap to adjoint for backward + GateType::SZ => Some(p.conjugate_szdg(q0)), + GateType::SZdg => Some(p.conjugate_sz(q0)), + GateType::SX => Some(p.conjugate_sxdg(q0)), + GateType::SXdg => Some(p.conjugate_sx(q0)), + GateType::SY => Some(p.conjugate_sydg(q0)), + GateType::SYdg => Some(p.conjugate_sy(q0)), + // Self-adjoint two-qubit gates + GateType::CX => { let q1 = gate.qubits[1].index() as u16; Some(p.conjugate_cx(q0, q1)) } + GateType::CZ => { let q1 = gate.qubits[1].index() as u16; Some(p.conjugate_cz(q0, q1)) } + GateType::SWAP => { let q1 = gate.qubits[1].index() as u16; p.conjugate_swap(q0, q1); Some(false) } + // CY is self-adjoint: CY = SZdg(t) CX(c,t) SZ(t) — chain + GateType::CY => { + let q1 = gate.qubits[1].index() as u16; + let s1 = p.conjugate_sz(q1); + let s2 = p.conjugate_cx(q0, q1); + let s3 = p.conjugate_szdg(q1); + Some((s1 as u8 + s2 as u8 + s3 as u8) % 2 == 1) + } + // Non-self-adjoint two-qubit: swap to adjoint for backward. + // SZZ backward = SZZdg forward = CX(q0,q1) SZdg(q1) CX(q0,q1) + GateType::SZZ => { + let q1 = gate.qubits[1].index() as u16; + let s1 = p.conjugate_cx(q0, q1); + let s2 = p.conjugate_szdg(q1); + let s3 = p.conjugate_cx(q0, q1); + Some((s1 as u8 + s2 as u8 + s3 as u8) % 2 == 1) + } + // SZZdg backward = SZZ forward = CX(q0,q1) SZ(q1) CX(q0,q1) + GateType::SZZdg => { + let q1 = gate.qubits[1].index() as u16; + let s1 = p.conjugate_cx(q0, q1); + let s2 = p.conjugate_sz(q1); + let s3 = p.conjugate_cx(q0, q1); + Some((s1 as u8 + s2 as u8 + s3 as u8) % 2 == 1) + } + // SXX backward = SXXdg forward = H(q0) H(q1) SZZdg H(q0) H(q1) + GateType::SXX => { + let q1 = gate.qubits[1].index() as u16; + let s1 = p.conjugate_h(q0); + let s2 = p.conjugate_h(q1); + let s3 = p.conjugate_cx(q0, q1); + let s4 = p.conjugate_szdg(q1); + let s5 = p.conjugate_cx(q0, q1); + let s6 = p.conjugate_h(q0); + let s7 = p.conjugate_h(q1); + let total = s1 as u8 + s2 as u8 + s3 as u8 + s4 as u8 + s5 as u8 + s6 as u8 + s7 as u8; + Some(total % 2 == 1) + } + // SXXdg backward = SXX forward + GateType::SXXdg => { + let q1 = gate.qubits[1].index() as u16; + let s1 = p.conjugate_h(q0); + let s2 = p.conjugate_h(q1); + let s3 = p.conjugate_cx(q0, q1); + let s4 = p.conjugate_sz(q1); + let s5 = p.conjugate_cx(q0, q1); + let s6 = p.conjugate_h(q0); + let s7 = p.conjugate_h(q1); + let total = s1 as u8 + s2 as u8 + s3 as u8 + s4 as u8 + s5 as u8 + s6 as u8 + s7 as u8; + Some(total % 2 == 1) + } + // SYY backward = SYYdg forward = SX(q0) SX(q1) SZZdg SXdg(q0) SXdg(q1) + GateType::SYY => { + let q1 = gate.qubits[1].index() as u16; + let s1 = p.conjugate_sxdg(q0); + let s2 = p.conjugate_sxdg(q1); + let s3 = p.conjugate_cx(q0, q1); + let s4 = p.conjugate_szdg(q1); + let s5 = p.conjugate_cx(q0, q1); + let s6 = p.conjugate_sx(q0); + let s7 = p.conjugate_sx(q1); + let total = s1 as u8 + s2 as u8 + s3 as u8 + s4 as u8 + s5 as u8 + s6 as u8 + s7 as u8; + Some(total % 2 == 1) + } + // SYYdg backward = SYY forward + GateType::SYYdg => { + let q1 = gate.qubits[1].index() as u16; + let s1 = p.conjugate_sx(q0); + let s2 = p.conjugate_sx(q1); + let s3 = p.conjugate_cx(q0, q1); + let s4 = p.conjugate_sz(q1); + let s5 = p.conjugate_cx(q0, q1); + let s6 = p.conjugate_sxdg(q0); + let s7 = p.conjugate_sxdg(q1); + let total = s1 as u8 + s2 as u8 + s3 as u8 + s4 as u8 + s5 as u8 + s6 as u8 + s7 as u8; + Some(total % 2 == 1) + } + // Gates that don't conjugate Paulis + GateType::PZ | GateType::QAlloc | GateType::QFree + | GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked + | GateType::I | GateType::Idle => None, + other => panic!("EEG Heisenberg: unsupported gate type {other:?}"), + } +} + +/// A term in the Heisenberg-propagated detector expansion. +#[derive(Clone, Debug)] +struct HeisenbergTerm { + /// Pauli operator (sparse: only stores non-identity qubits). + pauli: SparsePauli, + /// Complex coefficient (real, imaginary). + coeff_re: f64, + coeff_im: f64, +} + +/// Compute detection probability via backward Heisenberg propagation. +/// +/// Operates on the EXPANDED circuit (from [`crate::expand`]). Expansion +/// gates are automatically detected and skipped for noise injection. +/// +/// Handles both H-type (coherent) and S-type (stochastic) noise. +/// +/// # Arguments +/// * `gates` - The expanded circuit gates +/// * `detector` - Detector as Z on auxiliary qubit(s) (expanded frame) +/// * `noise` - Noise specification +/// * `initial_stab` - Stabilizer group of |0...0⟩ +/// * `prune_threshold` - Drop terms with |coefficient| below this (0 for exact) +pub fn heisenberg_detection_probability( + gates: &[Gate], + detector: &Bm, + noise: &dyn NoiseSpec, + initial_stab: &StabilizerGroup, + prune_threshold: f64, +) -> f64 { + heisenberg_windowed(gates, detector, noise, initial_stab, prune_threshold, None) +} + +/// Backward Heisenberg with precomputed noise map and BTreeMap-based merging. +/// +/// Uses BTreeMap for continuous dedup — no separate +/// merge step. Terms are merged on insert via BTreeMap's O(log n) lookup. +/// Also uses batched S-type scaling from the precomputed noise map. +pub fn heisenberg_with_noise_map( + gates: &[Gate], + detector: &Bm, + noise_map: &[Option], + initial_stab: &StabilizerGroup, + prune_threshold: f64, +) -> f64 { + let mut terms = vec![HeisenbergTerm { + pauli: SparsePauli::from_bm(detector), + coeff_re: 1.0, + coeff_im: 0.0, + }]; + + // Conservative active-qubit bitmap + let max_qubit = gates.iter() + .flat_map(|g| g.qubits.iter()) + .map(|q| q.index()) + .max() + .unwrap_or(0) + 1; + let mut active_qubits = vec![false; max_qubit]; + for &q in terms[0].pauli.x_qubits.iter().chain(terms[0].pauli.z_qubits.iter()) { + if (q as usize) < active_qubits.len() { active_qubits[q as usize] = true; } + } + + let mut last_merge_count = 1usize; + let mut sin_branches: Vec = Vec::new(); + + for i in (0..gates.len()).rev() { + let gate = &gates[i]; + let gate_qs: SmallVec<[u16; 4]> = gate.qubits.iter() + .map(|q| q.index() as u16).collect(); + + let gate_touches_active = gate_qs.iter() + .any(|&q| (q as usize) < active_qubits.len() && active_qubits[q as usize]); + + // Look up precomputed noise for this gate + let gate_noise = if gate_touches_active { noise_map.get(i).and_then(|n| n.as_ref()) } else { None }; + + if let Some(gn) = gate_noise { + // H-type injections (branching) + for inj in &gn.h_injections { + match inj.eeg_type { + crate::eeg::EegType::H => { + let h = inj.rate; + if h.abs() < 1e-20 { continue; } + let cos2h = (2.0 * h).cos(); + let sin2h = (2.0 * h).sin(); + + let single_z_qubit: Option = if inj.label.x_bits.is_zero() { + inj.label.z_bits.highest_set_bit().map(|q| q as u16) + } else { None }; + let noise_sparse = if single_z_qubit.is_none() { + Some(SparsePauli::from_bm(&inj.label)) + } else { None }; + + sin_branches.clear(); + let n = terms.len(); + for idx in 0..n { + let anticommutes = if let Some(q) = single_z_qubit { + terms[idx].pauli.has_x(q) + } else { + !terms[idx].pauli.commutes_with(noise_sparse.as_ref().unwrap()) + }; + if anticommutes { + let (sr, si) = (sin2h * terms[idx].coeff_re, sin2h * terms[idx].coeff_im); + let (dp, total_phase) = if let Some(q) = single_z_qubit { + let mut dp = terms[idx].pauli.clone(); + dp.toggle_z(q); + let has_x = terms[idx].pauli.has_x(q); + let has_z = terms[idx].pauli.has_z(q); + let phase = if has_x { if has_z { 3u8 } else { 1 } } else { 0 }; + (dp, (phase + 1) % 4) + } else { + let term_bm = terms[idx].pauli.to_bm(); + let (dp_bm, phase_exp) = inj.label.multiply_with_phase(&term_bm); + (SparsePauli::from_bm(&dp_bm), (phase_exp + 1) % 4) + }; + let (new_re, new_im) = match total_phase { + 0 => (sr, si), 1 => (-si, sr), + 2 => (-sr, -si), 3 => (si, -sr), + _ => unreachable!(), + }; + sin_branches.push(HeisenbergTerm { pauli: dp, coeff_re: new_re, coeff_im: new_im }); + terms[idx].coeff_re *= cos2h; + terms[idx].coeff_im *= cos2h; + } + } + // Merge sin branches: try binary search merge if terms + // are still sorted from last merge, else just extend. + for t in sin_branches.drain(..) { + for &q in t.pauli.x_qubits.iter().chain(t.pauli.z_qubits.iter()) { + let qu = q as usize; + if qu < active_qubits.len() { active_qubits[qu] = true; } + } + if last_merge_count == terms.len() { + match terms.binary_search_by(|p| p.pauli.cmp(&t.pauli)) { + Ok(idx) => { + terms[idx].coeff_re += t.coeff_re; + terms[idx].coeff_im += t.coeff_im; + continue; + } + Err(_) => { terms.push(t); } + } + } else { + terms.push(t); + } + } + } + crate::eeg::EegType::S => { + // Non-batched S-type (fallback for non-uniform noise) + let s = inj.rate; + if s.abs() < 1e-20 { continue; } + let p = -s; + let scale = 1.0 - 2.0 * p; + let single_q: Option = { + let xq = inj.label.x_bits.highest_set_bit(); + let zq = inj.label.z_bits.highest_set_bit(); + match (xq, zq) { + (Some(x), None) => Some(x as u16), + (None, Some(z)) => Some(z as u16), + (Some(x), Some(z)) if x == z => Some(x as u16), + _ => None, + } + }; + if let Some(q) = single_q { + let has_x_in_noise = inj.label.x_bits.highest_set_bit().is_some(); + let has_z_in_noise = inj.label.z_bits.highest_set_bit().is_some(); + for term in &mut terms { + let anti = (has_z_in_noise && term.pauli.has_x(q)) + || (has_x_in_noise && term.pauli.has_z(q)); + if anti { term.coeff_re *= scale; term.coeff_im *= scale; } + } + } else { + let ns = SparsePauli::from_bm(&inj.label); + for term in &mut terms { + if !term.pauli.commutes_with(&ns) { + term.coeff_re *= scale; term.coeff_im *= scale; + } + } + } + } + _ => {} + } + } + + // Batched S-type: apply combined scale factor + let s_scale = gn.q0_scale; // Same for all non-trivial support patterns + if (s_scale - 1.0).abs() > 1e-20 { + match gn.num_gate_qubits { + 1 => { + let q = gn.q0; + for term in &mut terms { + if term.pauli.has_x(q) || term.pauli.has_z(q) { + term.coeff_re *= s_scale; + term.coeff_im *= s_scale; + } + } + } + 2 => { + let q0 = gn.q0; + let q1 = gn.q1; + for term in &mut terms { + let on_q0 = term.pauli.has_x(q0) || term.pauli.has_z(q0); + let on_q1 = term.pauli.has_x(q1) || term.pauli.has_z(q1); + if on_q0 || on_q1 { + term.coeff_re *= s_scale; + term.coeff_im *= s_scale; + } + } + } + _ => {} + } + } + } + + // Step 2: Backward Clifford conjugation + if !gate_touches_active { continue; } + + match gate.gate_type { + GateType::PZ | GateType::QAlloc => { + terms.retain(|t| !gate_qs.iter().any(|&qi| t.pauli.has_x(qi))); + for t in &mut terms { + for &qi in &gate_qs { t.pauli.clear_z(qi); } + } + } + GateType::MZ => { + terms.retain(|t| !gate_qs.iter().any(|&qi| t.pauli.has_x(qi))); + } + _ => { + for t in &mut terms { + if let Some(sign_neg) = sparse_conjugate(&mut t.pauli, gate) { + if sign_neg { t.coeff_re = -t.coeff_re; t.coeff_im = -t.coeff_im; } + } + for &q in t.pauli.x_qubits.iter().chain(t.pauli.z_qubits.iter()) { + let qu = q as usize; + if qu < active_qubits.len() { active_qubits[qu] = true; } + } + } + } + } + + // Prune + if prune_threshold > 0.0 { + let thresh_sq = prune_threshold * prune_threshold; + terms.retain(|t| t.coeff_re * t.coeff_re + t.coeff_im * t.coeff_im > thresh_sq); + } + + // Merge: sort + dedup. In-place, no allocation, cache-friendly. + // For typical term counts (~50-100), this beats both HashMap and + // BTreeMap due to zero allocation overhead and sequential access. + let should_merge = match gate.gate_type { + GateType::PZ | GateType::QAlloc | GateType::MZ => terms.len() > 4, + _ => terms.len() > last_merge_count * 2 && terms.len() > 16, + }; + if should_merge { + terms.sort_unstable_by(|a, b| a.pauli.cmp(&b.pauli)); + let mut write = 0; + for read in 1..terms.len() { + if terms[read].pauli == terms[write].pauli { + terms[write].coeff_re += terms[read].coeff_re; + terms[write].coeff_im += terms[read].coeff_im; + } else { + if terms[write].coeff_re.abs() > 1e-30 || terms[write].coeff_im.abs() > 1e-30 { + write += 1; + } + if write < read { terms.swap(write, read); } + } + } + let final_len = if !terms.is_empty() + && (terms[write].coeff_re.abs() > 1e-30 || terms[write].coeff_im.abs() > 1e-30) + { write + 1 } else if terms.is_empty() { 0 } else { write }; + terms.truncate(final_len); + last_merge_count = terms.len().max(1); + } + } + + // Evaluate + let mut expectation_re = 0.0; + for term in &terms { + let eigenvalue = if term.pauli.is_identity() { 1.0 } else { + let bm = term.pauli.to_bm(); + match initial_stab.is_stabilizer(&bm) { + Some(true) => 1.0, Some(false) => -1.0, None => 0.0, + } + }; + expectation_re += term.coeff_re * eigenvalue; + } + (0.5 * (1.0 - expectation_re)).max(0.0).min(1.0) +} + +/// Backward Heisenberg with optional gate windowing. +/// +/// If `gate_window` is `Some((start, end))`, only walks gates in `[start, end)`. +/// Faster for large circuits but may miss long-range correlations. +/// Use `None` (or call [`heisenberg_detection_probability`]) for exact results. +pub fn heisenberg_windowed( + gates: &[Gate], + detector: &Bm, + noise: &dyn NoiseSpec, + initial_stab: &StabilizerGroup, + prune_threshold: f64, + gate_window: Option<(usize, usize)>, +) -> f64 { + // Start with the detector as a single sparse term + let mut terms = vec![HeisenbergTerm { + pauli: SparsePauli::from_bm(detector), + coeff_re: 1.0, + coeff_im: 0.0, + }]; + + // Identify expansion gates (virtual, no physical noise). + let expansion_gates = { + let mut exp = vec![false; gates.len()]; + if !gates.is_empty() && gates[0].gate_type == GateType::QAlloc { exp[0] = true; } + for i in 1..gates.len() { + if gates[i].gate_type == GateType::QAlloc { exp[i] = true; } + if gates[i].gate_type == GateType::CX && gates[i-1].gate_type == GateType::QAlloc { + let aq = gates[i-1].qubits[0].index(); + if gates[i].qubits.len() >= 2 && gates[i].qubits[1].index() == aq { + exp[i] = true; + if i+1 < gates.len() && gates[i+1].gate_type == GateType::PZ + && gates[i+1].qubits[0].index() == gates[i].qubits[0].index() { + exp[i+1] = true; + } + } + } + } + exp + }; + + let mut last_merge_count = 1usize; + // #3: Pre-allocate sin branches buffer, reused across noise sources + let mut sin_branches: Vec = Vec::new(); + + // Conservative active-qubit bitmap: once a qubit is active, stays active. + // This avoids the expensive per-term scan for gate relevance. + let max_qubit = gates.iter() + .flat_map(|g| g.qubits.iter()) + .map(|q| q.index()) + .max() + .unwrap_or(0) + 1; + let mut active_qubits = vec![false; max_qubit]; + // Seed from detector + for &q in terms[0].pauli.x_qubits.iter().chain(terms[0].pauli.z_qubits.iter()) { + if (q as usize) < active_qubits.len() { + active_qubits[q as usize] = true; + } + } + + // Walk backward through the circuit (optionally windowed) + let (walk_start, walk_end) = gate_window.unwrap_or((0, gates.len())); + for i in (walk_start..walk_end).rev() { + let gate = &gates[i]; + let gate_qs: SmallVec<[u16; 4]> = gate.qubits.iter() + .map(|q| q.index() as u16).collect(); + + // O(1) gate relevance check via bitmap (conservative: may visit some extra gates) + let gate_touches_active = gate_qs.iter() + .any(|&q| (q as usize) < active_qubits.len() && active_qubits[q as usize]); + + // Step 1: Apply noise adjoint (skip expansion gates). + if !expansion_gates[i] && gate_touches_active { + let qubits_usize: SmallVec<[usize; 4]> = gate_qs.iter() + .map(|&q| q as usize).collect(); + let injections = noise.noise_after_gate(i, gate.gate_type, &qubits_usize); + + for inj in &injections { + match inj.eeg_type { + crate::eeg::EegType::H => { + let h = inj.rate; + if h.abs() < 1e-20 { continue; } + + let cos2h = (2.0 * h).cos(); + let sin2h = (2.0 * h).sin(); + + let single_z_qubit: Option = if inj.label.x_bits.is_zero() { + inj.label.z_bits.highest_set_bit().map(|q| q as u16) + } else { + None + }; + let noise_sparse = if single_z_qubit.is_none() { + Some(SparsePauli::from_bm(&inj.label)) + } else { + None + }; + + // #3: Reuse sin_branches buffer + sin_branches.clear(); + let n = terms.len(); + + for idx in 0..n { + let anticommutes = if let Some(q) = single_z_qubit { + terms[idx].pauli.has_x(q) + } else { + !terms[idx].pauli.commutes_with(noise_sparse.as_ref().unwrap()) + }; + + if anticommutes { + let (sr, si) = + (sin2h * terms[idx].coeff_re, sin2h * terms[idx].coeff_im); + + let (dp, total_phase) = if let Some(q) = single_z_qubit { + let mut dp = terms[idx].pauli.clone(); + dp.toggle_z(q); + let has_x = terms[idx].pauli.has_x(q); + let has_z = terms[idx].pauli.has_z(q); + let phase = if has_x { if has_z { 3u8 } else { 1 } } else { 0 }; + (dp, (phase + 1) % 4) + } else { + let term_bm = terms[idx].pauli.to_bm(); + let (dp_bm, phase_exp) = + inj.label.multiply_with_phase(&term_bm); + (SparsePauli::from_bm(&dp_bm), (phase_exp + 1) % 4) + }; + + let (new_re, new_im) = match total_phase { + 0 => (sr, si), + 1 => (-si, sr), + 2 => (-sr, -si), + 3 => (si, -sr), + _ => unreachable!(), + }; + sin_branches.push(HeisenbergTerm { + pauli: dp, coeff_re: new_re, coeff_im: new_im, + }); + terms[idx].coeff_re *= cos2h; + terms[idx].coeff_im *= cos2h; + } + } + + // Update active bitmap BEFORE extending (only scan new branches) + for t in &sin_branches { + for &q in t.pauli.x_qubits.iter().chain(t.pauli.z_qubits.iter()) { + let qu = q as usize; + if qu < active_qubits.len() { active_qubits[qu] = true; } + } + } + terms.extend(sin_branches.drain(..)); + } + crate::eeg::EegType::S => { + let s = inj.rate; + if s.abs() < 1e-20 { continue; } + let p = -s; + let scale = 1.0 - 2.0 * p; + // For S-type, single-qubit specialization + let single_q: Option = { + let xq = inj.label.x_bits.highest_set_bit(); + let zq = inj.label.z_bits.highest_set_bit(); + match (xq, zq) { + (Some(x), None) => Some(x as u16), + (None, Some(z)) => Some(z as u16), + (Some(x), Some(z)) if x == z => Some(x as u16), + _ => None, + } + }; + + if let Some(q) = single_q { + // Single-qubit S noise: check just the one qubit + let has_x_in_noise = inj.label.x_bits.highest_set_bit().is_some(); + let has_z_in_noise = inj.label.z_bits.highest_set_bit().is_some(); + for term in &mut terms { + // Anticommutes if noise X overlaps term Z or noise Z overlaps term X + let anti = (has_z_in_noise && term.pauli.has_x(q)) + || (has_x_in_noise && term.pauli.has_z(q)); + if anti { + term.coeff_re *= scale; + term.coeff_im *= scale; + } + } + } else { + let noise_sparse = SparsePauli::from_bm(&inj.label); + for term in &mut terms { + if !term.pauli.commutes_with(&noise_sparse) { + term.coeff_re *= scale; + term.coeff_im *= scale; + } + } + } + } + _ => {} + } + + if prune_threshold > 0.0 { + terms.retain(|t| { + t.coeff_re * t.coeff_re + t.coeff_im * t.coeff_im + > prune_threshold * prune_threshold + }); + } + } + } + + // Step 2: Conjugate backward through the gate. + // #2: Skip gates that don't touch active qubits + if !gate_touches_active { + continue; + } + + match gate.gate_type { + // #4: Batch PZ/QAlloc — single pass through terms for all qubits + GateType::PZ | GateType::QAlloc => { + terms.retain(|t| { + !gate_qs.iter().any(|&qi| t.pauli.has_x(qi)) + }); + for t in &mut terms { + for &qi in &gate_qs { + t.pauli.clear_z(qi); + } + } + } + GateType::MZ => { + terms.retain(|t| { + !gate_qs.iter().any(|&qi| t.pauli.has_x(qi)) + }); + } + _ => { + for t in &mut terms { + if let Some(sign_neg) = sparse_conjugate(&mut t.pauli, gate) { + if sign_neg { + t.coeff_re = -t.coeff_re; + t.coeff_im = -t.coeff_im; + } + } + // Update active bitmap (CX can spread support to new qubits) + for &q in t.pauli.x_qubits.iter().chain(t.pauli.z_qubits.iter()) { + let qu = q as usize; + if qu < active_qubits.len() { active_qubits[qu] = true; } + } + } + } + } + + // Merge duplicate Pauli terms by sorting + linear scan. + let should_merge = match gate.gate_type { + GateType::PZ | GateType::QAlloc | GateType::MZ => terms.len() > 4, + _ => terms.len() > last_merge_count * 2 && terms.len() > 16, + }; + if should_merge { + terms.sort_unstable_by(|a, b| a.pauli.cmp(&b.pauli)); + let mut write = 0; + for read in 1..terms.len() { + if terms[read].pauli == terms[write].pauli { + let re = terms[read].coeff_re; + let im = terms[read].coeff_im; + terms[write].coeff_re += re; + terms[write].coeff_im += im; + } else { + if terms[write].coeff_re.abs() > 1e-30 + || terms[write].coeff_im.abs() > 1e-30 + { + write += 1; + } + if write < read { + terms.swap(write, read); + } + } + } + let final_len = if terms[write].coeff_re.abs() > 1e-30 + || terms[write].coeff_im.abs() > 1e-30 + { + write + 1 + } else { + write + }; + terms.truncate(final_len); + last_merge_count = terms.len().max(1); + } + } + + // Evaluate: p_D = (1/2)(1 - Re(Σ c_j ⟨ψ|Q_j|ψ⟩)) + let mut expectation_re = 0.0; + + for term in &terms { + let eigenvalue = if term.pauli.is_identity() { + 1.0 + } else { + // Convert sparse back to Bm for stabilizer check + let bm = term.pauli.to_bm(); + match initial_stab.is_stabilizer(&bm) { + Some(true) => 1.0, + Some(false) => -1.0, + None => 0.0, + } + }; + + expectation_re += term.coeff_re * eigenvalue; + } + + let prob = 0.5 * (1.0 - expectation_re); + prob.max(0.0).min(1.0) +} + +/// Backward Heisenberg with sparse gate traversal via precomputed index. +/// +/// Instead of iterating all gates, uses a `GateIndex` to visit only gates +/// on active qubits (qubits in any term's support). Maintains a binary +/// heap of pending gates and an active qubit set for O(1) relevance checks. +/// +/// For large circuits (d>=7), this is significantly faster than the linear +/// scan in [`heisenberg_windowed`] because most gates are irrelevant. +/// +/// Accepts an optional precomputed noise map. When provided, uses batched +/// S-type scaling (faster). When `None`, calls `noise.noise_after_gate()`. +pub fn heisenberg_sparse( + gates: &[Gate], + detector: &Bm, + noise: &dyn NoiseSpec, + initial_stab: &StabilizerGroup, + prune_threshold: f64, + gate_index: &crate::expand::GateIndex, + noise_map: Option<&[Option]>, +) -> f64 { + use std::collections::BinaryHeap; + + let mut terms = vec![HeisenbergTerm { + pauli: SparsePauli::from_bm(detector), + coeff_re: 1.0, + coeff_im: 0.0, + }]; + + // Active qubit set: union of all terms' support. + // Use a Vec for O(1) check (faster than BTreeSet for small qubit counts). + let num_qubits = gate_index.expansion_gates.len().min(gates.len()) + 64; + let mut active = vec![false; num_qubits.max(1)]; + + // Visited gate set: don't add the same gate to the heap twice. + let mut visited = vec![false; gates.len()]; + + // Populate initial active qubits and heap from detector support. + // Max-heap: pops largest gate index first (backward traversal). + let mut heap: BinaryHeap = BinaryHeap::new(); + + // Add gates on qubit q that are BEFORE `before_gate` (index < before_gate) to the heap. + // Gates at or after before_gate have already been passed in the backward walk. + fn activate_qubit( + q: u16, + before_gate: u32, + active: &mut [bool], + visited: &mut [bool], + heap: &mut BinaryHeap, + gate_index: &crate::expand::GateIndex, + ) { + let qu = q as usize; + if qu >= active.len() { return; } + active[qu] = true; + for gi in gate_index.gates_on_qubit_rev(qu) { + if gi >= before_gate { continue; } // already passed + let gi_usize = gi as usize; + if !visited[gi_usize] { + visited[gi_usize] = true; + heap.push(gi); + } + } + } + + // Seed from detector — all gates on detector qubits are candidates + let total_gates = gates.len() as u32; + for &q in &terms[0].pauli.x_qubits { + activate_qubit(q, total_gates, &mut active, &mut visited, &mut heap, gate_index); + } + for &q in &terms[0].pauli.z_qubits { + activate_qubit(q, total_gates, &mut active, &mut visited, &mut heap, gate_index); + } + + let mut last_merge_count = 1usize; + let mut sin_branches: Vec = Vec::new(); + + // Walk backward: pop gates from heap in reverse order (largest index first) + while let Some(gate_idx) = heap.pop() { + let i = gate_idx as usize; + let gate = &gates[i]; + let gate_qs: SmallVec<[u16; 4]> = gate.qubits.iter() + .map(|q| q.index() as u16).collect(); + + // Step 1: Apply noise adjoint (skip expansion gates). + if !gate_index.is_expansion(i) { + // Get noise: from precomputed map if available, else dynamic + let precomputed = noise_map.and_then(|nm| nm.get(i).and_then(|n| n.as_ref())); + + // Get injections: from noise map or dynamic noise spec + let dynamic_injections = if precomputed.is_none() { + let qubits_usize: SmallVec<[usize; 4]> = gate_qs.iter() + .map(|&q| q as usize).collect(); + noise.noise_after_gate(i, gate.gate_type, &qubits_usize) + } else { + Vec::new() + }; + let injections: &[crate::noise::NoiseInjection] = if let Some(gn) = precomputed { + &gn.h_injections + } else { + &dynamic_injections + }; + + for inj in injections { + match inj.eeg_type { + crate::eeg::EegType::H => { + let h = inj.rate; + if h.abs() < 1e-20 { continue; } + + let cos2h = (2.0 * h).cos(); + let sin2h = (2.0 * h).sin(); + + let single_z_qubit: Option = if inj.label.x_bits.is_zero() { + inj.label.z_bits.highest_set_bit().map(|q| q as u16) + } else { + None + }; + let noise_sparse = if single_z_qubit.is_none() { + Some(SparsePauli::from_bm(&inj.label)) + } else { + None + }; + + sin_branches.clear(); + let n = terms.len(); + + for idx in 0..n { + let anticommutes = if let Some(q) = single_z_qubit { + terms[idx].pauli.has_x(q) + } else { + !terms[idx].pauli.commutes_with(noise_sparse.as_ref().unwrap()) + }; + + if anticommutes { + let (sr, si) = + (sin2h * terms[idx].coeff_re, sin2h * terms[idx].coeff_im); + + let (dp, total_phase) = if let Some(q) = single_z_qubit { + let mut dp = terms[idx].pauli.clone(); + dp.toggle_z(q); + let has_x = terms[idx].pauli.has_x(q); + let has_z = terms[idx].pauli.has_z(q); + let phase = if has_x { if has_z { 3u8 } else { 1 } } else { 0 }; + (dp, (phase + 1) % 4) + } else { + let term_bm = terms[idx].pauli.to_bm(); + let (dp_bm, phase_exp) = + inj.label.multiply_with_phase(&term_bm); + (SparsePauli::from_bm(&dp_bm), (phase_exp + 1) % 4) + }; + + let (new_re, new_im) = match total_phase { + 0 => (sr, si), + 1 => (-si, sr), + 2 => (-sr, -si), + 3 => (si, -sr), + _ => unreachable!(), + }; + + // Check if new term activates new qubits + for &q in &dp.x_qubits { + activate_qubit(q, gate_idx, &mut active, &mut visited, &mut heap, gate_index); + } + for &q in &dp.z_qubits { + activate_qubit(q, gate_idx, &mut active, &mut visited, &mut heap, gate_index); + } + + sin_branches.push(HeisenbergTerm { + pauli: dp, coeff_re: new_re, coeff_im: new_im, + }); + terms[idx].coeff_re *= cos2h; + terms[idx].coeff_im *= cos2h; + } + } + + terms.extend(sin_branches.drain(..)); + } + crate::eeg::EegType::S => { + // S-type: process individually. When using noise map, + // the batched scaling below handles the common case, + // but unbatchable S injections are placed in h_injections + // and must be processed here. + let s = inj.rate; + if s.abs() < 1e-20 { continue; } + let p = -s; + let scale = 1.0 - 2.0 * p; + + let single_q: Option = { + let xq = inj.label.x_bits.highest_set_bit(); + let zq = inj.label.z_bits.highest_set_bit(); + match (xq, zq) { + (Some(x), None) => Some(x as u16), + (None, Some(z)) => Some(z as u16), + (Some(x), Some(z)) if x == z => Some(x as u16), + _ => None, + } + }; + + if let Some(q) = single_q { + let has_x_in_noise = inj.label.x_bits.highest_set_bit().is_some(); + let has_z_in_noise = inj.label.z_bits.highest_set_bit().is_some(); + for term in &mut terms { + let anti = (has_z_in_noise && term.pauli.has_x(q)) + || (has_x_in_noise && term.pauli.has_z(q)); + if anti { + term.coeff_re *= scale; + term.coeff_im *= scale; + } + } + } else { + let noise_sparse = SparsePauli::from_bm(&inj.label); + for term in &mut terms { + if !term.pauli.commutes_with(&noise_sparse) { + term.coeff_re *= scale; + term.coeff_im *= scale; + } + } + } + } + _ => {} + } + } + + // Batched S-type scaling from noise map (much faster than per-injection) + if let Some(gn) = precomputed { + let s_scale = gn.q0_scale; + if (s_scale - 1.0).abs() > 1e-20 { + match gn.num_gate_qubits { + 1 => { + let q = gn.q0; + for term in &mut terms { + if term.pauli.has_x(q) || term.pauli.has_z(q) { + term.coeff_re *= s_scale; + term.coeff_im *= s_scale; + } + } + } + 2 => { + let q0 = gn.q0; + let q1 = gn.q1; + for term in &mut terms { + let on_q0 = term.pauli.has_x(q0) || term.pauli.has_z(q0); + let on_q1 = term.pauli.has_x(q1) || term.pauli.has_z(q1); + if on_q0 || on_q1 { + term.coeff_re *= s_scale; + term.coeff_im *= s_scale; + } + } + } + _ => {} + } + } + } + } + + // Step 2: Backward Clifford conjugation. + match gate.gate_type { + GateType::PZ | GateType::QAlloc => { + terms.retain(|t| { + !gate_qs.iter().any(|&qi| t.pauli.has_x(qi)) + }); + for t in &mut terms { + for &qi in &gate_qs { + t.pauli.clear_z(qi); + } + } + } + GateType::MZ => { + terms.retain(|t| { + !gate_qs.iter().any(|&qi| t.pauli.has_x(qi)) + }); + } + _ => { + for t in &mut terms { + if let Some(sign_neg) = sparse_conjugate(&mut t.pauli, gate) { + if sign_neg { + t.coeff_re = -t.coeff_re; + t.coeff_im = -t.coeff_im; + } + } + + // Activate any NEW qubits from conjugation (e.g., CX spreads Z) + for &q in t.pauli.x_qubits.iter().chain(t.pauli.z_qubits.iter()) { + activate_qubit(q, gate_idx, &mut active, &mut visited, &mut heap, gate_index); + } + } + } + } + + // Prune + if prune_threshold > 0.0 { + let thresh_sq = prune_threshold * prune_threshold; + terms.retain(|t| { + t.coeff_re * t.coeff_re + t.coeff_im * t.coeff_im > thresh_sq + }); + } + + // Merge duplicate Pauli terms. + let should_merge = match gate.gate_type { + GateType::PZ | GateType::QAlloc | GateType::MZ => terms.len() > 4, + _ => terms.len() > last_merge_count * 2 && terms.len() > 16, + }; + if should_merge { + terms.sort_unstable_by(|a, b| a.pauli.cmp(&b.pauli)); + let mut write = 0; + for read in 1..terms.len() { + if terms[read].pauli == terms[write].pauli { + let re = terms[read].coeff_re; + let im = terms[read].coeff_im; + terms[write].coeff_re += re; + terms[write].coeff_im += im; + } else { + if terms[write].coeff_re.abs() > 1e-30 + || terms[write].coeff_im.abs() > 1e-30 + { + write += 1; + } + if write < read { + terms.swap(write, read); + } + } + } + let final_len = if !terms.is_empty() + && (terms[write].coeff_re.abs() > 1e-30 || terms[write].coeff_im.abs() > 1e-30) + { + write + 1 + } else if terms.is_empty() { + 0 + } else { + write + }; + terms.truncate(final_len); + last_merge_count = terms.len().max(1); + } + } + + // Evaluate + let mut expectation_re = 0.0; + for term in &terms { + let eigenvalue = if term.pauli.is_identity() { + 1.0 + } else { + let bm = term.pauli.to_bm(); + match initial_stab.is_stabilizer(&bm) { + Some(true) => 1.0, + Some(false) => -1.0, + None => 0.0, + } + }; + expectation_re += term.coeff_re * eigenvalue; + } + + let prob = 0.5 * (1.0 - expectation_re); + prob.max(0.0).min(1.0) +} + +/// Convenience: expand an original circuit and compute detection probability. +pub fn heisenberg_detection_probability_from_circuit( + original_gates: &[Gate], + detector_meas_indices: &[usize], + noise: &dyn NoiseSpec, + num_original_qubits: usize, + prune_threshold: f64, +) -> f64 { + let expanded = crate::expand::expand_circuit(original_gates); + + let mut detector = Bm::default(); + for &m in detector_meas_indices { + if m < expanded.measurement_qubit.len() { + detector.z_bits.set_bit(expanded.measurement_qubit[m]); + } + } + + let init_gates: Vec = (0..num_original_qubits) + .map(|q| crate::expand::make_gate(GateType::PZ, &[q])) + .collect(); + let stab = StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); + + heisenberg_detection_probability(&expanded.gates, &detector, noise, &stab, prune_threshold) +} + +/// Exact detection probability via matrix-based backward Heisenberg. +/// +/// Computes the backward adjoint using dense 2^n × 2^n complex matrix +/// multiplication. Exact for any circuit, but limited to ~20 expanded +/// qubits by memory. Useful as a reference/validation for the faster +/// Pauli-tracking walk ([`heisenberg_detection_probability_from_circuit`]). +pub fn heisenberg_exact_from_circuit( + original_gates: &[Gate], + detector_meas_indices: &[usize], + noise: &dyn NoiseSpec, + _num_original_qubits: usize, +) -> f64 { + let expanded = crate::expand::expand_circuit(original_gates); + let n = expanded.num_qubits; + + if n > 20 { + panic!("Matrix Heisenberg requires 2^n memory; {n} qubits is too large. Use the Pauli-tracking walk for approximate results."); + } + + let dim = 1usize << n; + + // Build detector matrix: diagonal with Z eigenvalues on the detector aux qubits. + let mut obs_re = vec![0.0f64; dim * dim]; + let obs_im = vec![0.0f64; dim * dim]; + for i in 0..dim { + let mut eigenvalue = 1.0f64; + for &m in detector_meas_indices { + if m < expanded.measurement_qubit.len() { + let aux = expanded.measurement_qubit[m]; + if (i >> aux) & 1 == 1 { eigenvalue = -eigenvalue; } + } + } + obs_re[i * dim + i] = eigenvalue; + } + + // Identify expansion gates + let expansion_gates = find_expansion_gates(&expanded.gates); + + // Walk backward, applying adjoints via matrix multiplication. + let mut im = obs_im; + for idx in (0..expanded.gates.len()).rev() { + let g = &expanded.gates[idx]; + let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + + // Noise adjoint (skip expansion gates) + if !expansion_gates[idx] { + let injections = noise.noise_after_gate(idx, g.gate_type, &qs); + for inj in &injections { + if inj.eeg_type != crate::eeg::EegType::H { continue; } + if inj.rate.abs() < 1e-20 { continue; } + // RZ(θ) on the noise qubit, where θ = 2*rate + let theta = 2.0 * inj.rate; + // Find which qubit the noise acts on + let noise_q = if let Some(q) = inj.label.z_bits.highest_set_bit() { + q + } else if let Some(q) = inj.label.x_bits.highest_set_bit() { + q + } else { + continue; + }; + matrix_rz_adjoint(&mut obs_re, &mut im, noise_q, theta, n); + } + } + + // Gate adjoint + match g.gate_type { + GateType::PZ | GateType::QAlloc => { + matrix_pz_adjoint(&mut obs_re, &mut im, qs[0], n); + } + GateType::MZ => { + matrix_mz_adjoint(&mut obs_re, &mut im, qs[0], n); + } + GateType::H => { + matrix_h_adjoint(&mut obs_re, &mut im, qs[0], n); + } + GateType::CX => { + if qs.len() >= 2 { + matrix_cx_adjoint(&mut obs_re, &mut im, qs[0], qs[1], n); + } + } + _ => {} + } + } + + // ⟨0...0|O_backward|0...0⟩ = obs_re[0] + let expectation = obs_re[0]; + let prob = 0.5 * (1.0 - expectation); + prob.max(0.0).min(1.0) +} + +// --- Matrix helpers for exact Heisenberg --- + +fn matrix_rz_adjoint(re: &mut [f64], im: &mut [f64], q: usize, theta: f64, n: usize) { + let dim = 1usize << n; + for i in 0..dim { + let bi = ((i >> q) & 1) as f64; + for j in 0..dim { + let bj = ((j >> q) & 1) as f64; + let phase = (bi - bj) * theta; + if phase.abs() < 1e-20 { continue; } + let (cp, sp) = (phase.cos(), phase.sin()); + let idx = i * dim + j; + let (r, m) = (re[idx], im[idx]); + re[idx] = cp * r - sp * m; + im[idx] = sp * r + cp * m; + } + } +} + +fn matrix_pz_adjoint(re: &mut [f64], im: &mut [f64], q: usize, n: usize) { + let dim = 1usize << n; + let mask = 1usize << q; + for i in 0..dim { + let iq = (i >> q) & 1; + for j in 0..dim { + let jq = (j >> q) & 1; + let idx = i * dim + j; + if iq != jq { + re[idx] = 0.0; + im[idx] = 0.0; + } else { + let i0 = i & !mask; + let j0 = j & !mask; + let idx0 = i0 * dim + j0; + re[idx] = re[idx0]; + im[idx] = im[idx0]; + } + } + } +} + +fn matrix_mz_adjoint(re: &mut [f64], im: &mut [f64], q: usize, n: usize) { + let dim = 1usize << n; + for i in 0..dim { + let iq = (i >> q) & 1; + for j in 0..dim { + let jq = (j >> q) & 1; + if iq != jq { + let idx = i * dim + j; + re[idx] = 0.0; + im[idx] = 0.0; + } + } + } +} + +fn matrix_h_adjoint(re: &mut [f64], im: &mut [f64], q: usize, n: usize) { + let dim = 1usize << n; + let mask = 1usize << q; + let mut new_re = vec![0.0f64; dim * dim]; + let mut new_im = vec![0.0f64; dim * dim]; + for i in 0..dim { + let i0 = i & !mask; + let i1 = i | mask; + let iq = (i >> q) & 1; + for j in 0..dim { + let j0 = j & !mask; + let j1 = j | mask; + let jq = (j >> q) & 1; + let mut sr = 0.0; + let mut si = 0.0; + for a in 0..2usize { + for b in 0..2usize { + let ia = if a == 0 { i0 } else { i1 }; + let jb = if b == 0 { j0 } else { j1 }; + let sign = if (iq * a + b * jq) % 2 == 0 { 0.5 } else { -0.5 }; + let idx = ia * dim + jb; + sr += sign * re[idx]; + si += sign * im[idx]; + } + } + new_re[i * dim + j] = sr; + new_im[i * dim + j] = si; + } + } + re.copy_from_slice(&new_re); + im.copy_from_slice(&new_im); +} + +fn matrix_cx_adjoint(re: &mut [f64], im: &mut [f64], control: usize, target: usize, n: usize) { + let dim = 1usize << n; + let cmask = 1usize << control; + let tmask = 1usize << target; + let cx_perm = |i: usize| -> usize { + if (i & cmask) != 0 { i ^ tmask } else { i } + }; + let mut new_re = vec![0.0f64; dim * dim]; + let mut new_im = vec![0.0f64; dim * dim]; + for i in 0..dim { + let ci = cx_perm(i); + for j in 0..dim { + let cj = cx_perm(j); + new_re[i * dim + j] = re[ci * dim + cj]; + new_im[i * dim + j] = im[ci * dim + cj]; + } + } + re.copy_from_slice(&new_re); + im.copy_from_slice(&new_im); +} + +/// Identify expansion gate indices. +fn find_expansion_gates(gates: &[Gate]) -> Vec { + let mut exp = vec![false; gates.len()]; + if !gates.is_empty() && gates[0].gate_type == GateType::QAlloc { exp[0] = true; } + for i in 1..gates.len() { + if gates[i].gate_type == GateType::QAlloc { exp[i] = true; } + if gates[i].gate_type == GateType::CX && gates[i-1].gate_type == GateType::QAlloc { + let aq = gates[i-1].qubits[0].index(); + if gates[i].qubits.len() >= 2 && gates[i].qubits[1].index() == aq { + exp[i] = true; + if i+1 < gates.len() && gates[i+1].gate_type == GateType::PZ + && gates[i+1].qubits[0].index() == gates[i].qubits[0].index() { + exp[i+1] = true; + } + } + } + } + exp +} + +#[cfg(test)] +mod tests { + use super::*; + use pecos_core::{GateAngles, GateParams, GateQubits, QubitId}; + use crate::noise::UniformNoise; + use crate::expand; + + fn gate(gt: GateType, qubits: &[usize]) -> Gate { + Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), + } + } + + #[test] + fn test_d2_zbasis_heisenberg_original_circuit() { + // d=2 Z-basis surface code (2 rounds) — the circuit where forward EEG + // has a ~50% gap. Test if Heisenberg closes it. + // + // Circuit: 7 qubits (0-3 data, 4-6 ancilla) + // X-check ancillas: 4, 5 (H, CX, CX, H, MZ) + // Z-check ancilla: 6 (CX, CX, MZ) + let gates_orig = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), gate(GateType::PZ, &[3]), + gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[6]), + // Round 1 + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), + gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), + gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), + gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::MZ, &[6]), + // Reset + gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[6]), + // Round 2 + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), + gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), + gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), + gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::MZ, &[6]), + // Final data readout + gate(GateType::MZ, &[0]), gate(GateType::MZ, &[1]), + gate(GateType::MZ, &[2]), gate(GateType::MZ, &[3]), + ]; + + let expanded = expand::expand_circuit(&gates_orig); + let theta = 0.05; + let noise = UniformNoise::coherent_only(theta); + + // Initial state stabilizer group: Z on each PZ-initialized qubit. + // At circuit start, all original qubits are |0⟩. + // (Aux qubits are QAlloc'd later during the circuit.) + let init_gates: Vec = (0..7).map(|q| gate(GateType::PZ, &[q])).collect(); + let stab = StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); + + // D1: ancilla 4 round comparison (Z on aux for meas 0 and meas 3) + let aux_m0 = expanded.measurement_qubit[0]; // q4 round 1 + let aux_m3 = expanded.measurement_qubit[3]; // q4 round 2 + let mut det1 = Bm::default(); + det1.z_bits.set_bit(aux_m0); + det1.z_bits.set_bit(aux_m3); + + // D2: ancilla 5 round comparison + let aux_m1 = expanded.measurement_qubit[1]; // q5 round 1 + let aux_m4 = expanded.measurement_qubit[4]; // q5 round 2 + let mut det2 = Bm::default(); + det2.z_bits.set_bit(aux_m1); + det2.z_bits.set_bit(aux_m4); + + // Run Heisenberg for both detectors + let p1_heis = heisenberg_detection_probability( + &expanded.gates, &det1, &noise, &stab, 1e-10, + ); + let p2_heis = heisenberg_detection_probability( + &expanded.gates, &det2, &noise, &stab, 1e-10, + ); + + // For comparison: forward EEG + let eeg_result = crate::circuit::analyze_with_noise(&expanded.gates, &noise); + let dets = vec![ + crate::dem_mapping::Detector { id: 1, stabilizer: det1 }, + crate::dem_mapping::Detector { id: 2, stabilizer: det2 }, + ]; + let entries = crate::dem_mapping::build_dem_configured( + &eeg_result.generators, &dets, &[], + Some(&stab), &crate::dem_mapping::EegConfig::default(), + ); + let mut eeg_d1 = 0.0; + let mut eeg_d2 = 0.0; + for e in &entries { + for &d in &e.event.detectors { + if d == 1 { eeg_d1 += e.probability; } + if d == 2 { eeg_d2 += e.probability; } + } + } + + eprintln!("\nd=2 Z-basis, theta={theta}:"); + eprintln!(" D1: Heisenberg={p1_heis:.6}, EEG={eeg_d1:.6}"); + eprintln!(" D2: Heisenberg={p2_heis:.6}, EEG={eeg_d2:.6}"); + + // Heisenberg should give DIFFERENT values for D1 and D2 + // (unlike EEG which gives them equal due to missing time-ordering) + if (p1_heis - p2_heis).abs() > 1e-6 { + eprintln!(" Heisenberg correctly distinguishes D1 and D2!"); + } + } + + #[test] + fn test_single_x_check_heisenberg() { + // Simplest X-check: 2 data + 1 ancilla, 2 rounds. + // Detector: Z on ancilla (qubit 2) — passes through both MZ(2) gates. + // The round-comparison detector fires when the two MZ outcomes differ. + let gates_orig = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + // Round 1 + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + gate(GateType::PZ, &[2]), + // Round 2 + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + ]; + + let theta = 0.05; + let noise = UniformNoise::coherent_only(theta); + + // Initial state: Z on each qubit + let init_gates: Vec = (0..3).map(|q| gate(GateType::PZ, &[q])).collect(); + let stab = StabilizerGroup::from_circuit(&init_gates, 3); + + // Detector: Z on ancilla qubit 2 (round-comparison) + let det = Bm::z(2); + + let p_heis = heisenberg_detection_probability( + &gates_orig, &det, &noise, &stab, 0.0, + ); + + eprintln!("\nSimple X-check (original circuit), theta={theta}:"); + eprintln!(" Heisenberg: {p_heis:.6}"); + } + + #[test] + fn test_bell_parity_exact() { + // Bell parity: PZ(0,1), H(0), CX(0,1), H(0), H(1), MZ(0), MZ(1) + // Parity detector: Z_0 * Z_1 (on original qubits) + // Exact answer: p = sin²(theta) + let gates_orig = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), + gate(GateType::H, &[0]), + gate(GateType::CX, &[0, 1]), + gate(GateType::H, &[0]), gate(GateType::H, &[1]), + gate(GateType::MZ, &[0]), gate(GateType::MZ, &[1]), + ]; + + // Parity detector: Z on both measured qubits (original frame) + let mut det = Bm::default(); + det.z_bits.set_bit(0); + det.z_bits.set_bit(1); + + // Initial state: Z on each qubit + let init_gates: Vec = (0..2).map(|q| gate(GateType::PZ, &[q])).collect(); + let stab = StabilizerGroup::from_circuit(&init_gates, 2); + + for &theta in &[0.01, 0.05, 0.1, 0.2, 0.5] { + let noise = UniformNoise::coherent_only(theta); + + let p = heisenberg_detection_probability( + &gates_orig, &det, &noise, &stab, 0.0, + ); + + let exact = theta.sin().powi(2); + let eeg_taylor = theta * theta; // leading-order EEG + + eprintln!("theta={theta:.2}: Heisenberg={p:.6}, exact={exact:.6}, Taylor={eeg_taylor:.6}"); + + // Heisenberg should match exact much better than Taylor + assert!((p - exact).abs() < 0.01, + "theta={theta}: Heisenberg {p:.6} vs exact {exact:.6}, diff={:.6}", (p-exact).abs()); + } + } + + #[test] + fn test_exact_bell_parity() { + // Matrix-based exact Heisenberg should match sin²(θ) perfectly. + let gates = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), + gate(GateType::H, &[0]), + gate(GateType::CX, &[0, 1]), + gate(GateType::H, &[0]), gate(GateType::H, &[1]), + gate(GateType::MZ, &[0]), gate(GateType::MZ, &[1]), + ]; + + for &theta in &[0.01, 0.05, 0.1, 0.2, 0.5] { + let noise = crate::noise::UniformNoise::coherent_only(theta); + let p = heisenberg_exact_from_circuit(&gates, &[0, 1], &noise, 2); + let exact = theta.sin().powi(2); + assert!((p - exact).abs() < 1e-10, + "theta={theta}: exact_heisenberg {p:.10} vs sin²(θ) {exact:.10}"); + } + } + + #[test] + fn test_exact_2round_xcheck() { + // Matrix Heisenberg on the simplest failing case: 2-round, 1 ancilla. + // Exact analytical: P = [2 - cos(6θ) - cos(2θ)] / 4. + let gates = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + ]; + + for &theta in &[0.01, 0.05, 0.1, 0.2] { + let noise = crate::noise::UniformNoise::coherent_only(theta); + let p = heisenberg_exact_from_circuit(&gates, &[0, 1], &noise, 3); + let exact = (2.0 - (6.0 * theta).cos() - (2.0 * theta).cos()) / 4.0; + eprintln!("theta={theta:.2}: exact_heisenberg={p:.10}, analytical={exact:.10}"); + assert!((p - exact).abs() < 1e-8, + "theta={theta}: got {p:.10}, expected {exact:.10}, diff={:.2e}", (p-exact).abs()); + } + } + + /// Verify heisenberg_sparse produces identical results to heisenberg_windowed, + /// and measure the speedup from sparse traversal. + #[test] + fn test_sparse_matches_windowed_and_timing() { + use std::time::Instant; + + // Build a d=2 Z-basis surface code with 2 rounds (same as test above) + let gates_orig = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), gate(GateType::PZ, &[3]), + gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[6]), + // Round 1 + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), + gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), + gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), + gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::MZ, &[6]), + // Reset + Round 2 + gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[6]), + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), + gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), + gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), + gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::MZ, &[6]), + ]; + + let expanded = crate::expand::expand_circuit(&gates_orig); + let gate_index = crate::expand::GateIndex::build(&expanded.gates, expanded.num_qubits); + + let init_gates: Vec = (0..7) + .map(|q| gate(GateType::PZ, &[q])) + .collect(); + let stab = crate::stabilizer::StabilizerGroup::from_circuit( + &init_gates, expanded.num_qubits, + ); + + // Test both coherent-only and depolarizing noise + let noise_configs: Vec<(&str, crate::noise::UniformNoise)> = vec![ + ("coherent_only", crate::noise::UniformNoise::coherent_only(0.05)), + ("depolarizing", crate::noise::UniformNoise { idle_rz: 0.0, p1: 0.001, p2: 0.01, p_meas: 0.001, p_prep: 0.001 }), + ("combined", crate::noise::UniformNoise { idle_rz: 0.05, p1: 0.001, p2: 0.01, p_meas: 0.001, p_prep: 0.001 }), + ]; + + for (label, noise) in &noise_configs { + let noise_map = build_noise_map( + &expanded.gates, noise, &gate_index.expansion_gates, + ); + + // Test all 3 detectors (auxiliary qubits in round 1: meas 0,1,2) + for meas_idx in 0..3 { + let aux_q = expanded.measurement_qubit[meas_idx]; + let det = Bm::z(aux_q); + + // Windowed (old path) + let start = Instant::now(); + let p_windowed = heisenberg_windowed( + &expanded.gates, &det, noise, &stab, 1e-12, None, + ); + let t_windowed = start.elapsed(); + + // Sparse without noise map + let start = Instant::now(); + let p_sparse = heisenberg_sparse( + &expanded.gates, &det, noise, &stab, 1e-12, + &gate_index, None, + ); + let t_sparse = start.elapsed(); + + // Sparse with noise map + let start = Instant::now(); + let p_sparse_nm = heisenberg_sparse( + &expanded.gates, &det, noise, &stab, 1e-12, + &gate_index, Some(&noise_map), + ); + let t_sparse_nm = start.elapsed(); + + // With noise map (old path) + let start = Instant::now(); + let p_nm = heisenberg_with_noise_map( + &expanded.gates, &det, &noise_map, &stab, 1e-12, + ); + let t_nm = start.elapsed(); + + // Verify exact match + let tol = 1e-12; + assert!((p_windowed - p_sparse).abs() < tol, + "{label} det{meas_idx}: windowed={p_windowed:.15} vs sparse={p_sparse:.15}, diff={:.2e}", + (p_windowed - p_sparse).abs()); + assert!((p_windowed - p_sparse_nm).abs() < tol, + "{label} det{meas_idx}: windowed={p_windowed:.15} vs sparse+nm={p_sparse_nm:.15}, diff={:.2e}", + (p_windowed - p_sparse_nm).abs()); + assert!((p_windowed - p_nm).abs() < tol, + "{label} det{meas_idx}: windowed={p_windowed:.15} vs nm={p_nm:.15}, diff={:.2e}", + (p_windowed - p_nm).abs()); + + eprintln!(" {label} det{meas_idx}: p={p_windowed:.8} \ + windowed={:.1}us sparse={:.1}us sparse+nm={:.1}us nm={:.1}us", + t_windowed.as_secs_f64() * 1e6, + t_sparse.as_secs_f64() * 1e6, + t_sparse_nm.as_secs_f64() * 1e6, + t_nm.as_secs_f64() * 1e6); + } + } + } + + /// Scaling benchmark: sparse vs windowed at d=3..11 repetition codes. + /// + /// Builds larger circuits and measures per-detector walk time with both + /// implementations. Verifies results match exactly. + #[test] + #[ignore] // run with: cargo test -p pecos-eeg -- bench_sparse_scaling --ignored --nocapture + fn bench_sparse_scaling() { + use std::time::Instant; + + let noise = crate::noise::UniformNoise { + idle_rz: 0.05, p1: 0.001, p2: 0.01, p_meas: 0.001, p_prep: 0.001, + }; + + eprintln!("\n=== Sparse vs Windowed scaling (combined noise) ==="); + eprintln!("{:>4} {:>6} {:>8} {:>8} {:>6} {:>12} {:>12} {:>8}", + "d", "rnds", "gates", "exp_q", "n_det", "windowed_ms", "sparse_ms", "speedup"); + + // Test with increasing circuit sizes. + // Repetition codes are 1D — detectors propagate through most gates. + // Surface codes are 2D — detectors are local (touch ~8 out of d^2 qubits). + // Test both to show where sparsity helps. + + // --- Repetition codes (1D, low sparsity) --- + eprintln!("\n--- Repetition codes (1D) ---"); + let rep_configs: Vec<(usize, usize)> = vec![ + (5, 3), (5, 10), (9, 3), (9, 10), (13, 3), (13, 10), + ]; + + for &(d, num_rounds) in &rep_configs { + let num_data = d; + let num_ancilla = d - 1; + let num_qubits = num_data + num_ancilla; + + // Build repetition code + let mut gates = Vec::new(); + for q in 0..num_qubits { + gates.push(gate(GateType::PZ, &[q])); + } + for round in 0..num_rounds { + for i in 0..num_ancilla { + gates.push(gate(GateType::H, &[num_data + i])); + } + for i in 0..num_ancilla { + gates.push(gate(GateType::CX, &[num_data + i, i])); + } + for i in 0..num_ancilla { + gates.push(gate(GateType::CX, &[num_data + i, i + 1])); + } + for i in 0..num_ancilla { + gates.push(gate(GateType::H, &[num_data + i])); + } + for i in 0..num_ancilla { + gates.push(gate(GateType::MZ, &[num_data + i])); + } + if round < num_rounds - 1 { + for i in 0..num_ancilla { + gates.push(gate(GateType::PZ, &[num_data + i])); + } + } + } + for q in 0..num_data { + gates.push(gate(GateType::MZ, &[q])); + } + + let expanded = crate::expand::expand_circuit(&gates); + let gate_index = crate::expand::GateIndex::build(&expanded.gates, expanded.num_qubits); + let noise_map = build_noise_map(&expanded.gates, &noise, &gate_index.expansion_gates); + + let init_gates: Vec = (0..num_qubits) + .map(|q| gate(GateType::PZ, &[q])) + .collect(); + let stab = crate::stabilizer::StabilizerGroup::from_circuit( + &init_gates, expanded.num_qubits, + ); + + // Build detectors: round-to-round comparison + let num_detectors = num_ancilla * (num_rounds - 1); + let mut detectors = Vec::new(); + for round in 0..(num_rounds - 1) { + for i in 0..num_ancilla { + let m1 = round * num_ancilla + i; + let m2 = (round + 1) * num_ancilla + i; + let aux1 = expanded.measurement_qubit[m1]; + let aux2 = expanded.measurement_qubit[m2]; + let det_bm = Bm::z(aux1).multiply(&Bm::z(aux2)); + detectors.push(det_bm); + } + } + + // Time windowed (old path) + let start = Instant::now(); + let mut p_windowed = Vec::new(); + for det in &detectors { + p_windowed.push(heisenberg_with_noise_map( + &expanded.gates, det, &noise_map, &stab, 1e-12, + )); + } + let t_windowed = start.elapsed(); + + // Time sparse (new path) + let start = Instant::now(); + let mut p_sparse = Vec::new(); + for det in &detectors { + p_sparse.push(heisenberg_sparse( + &expanded.gates, det, &noise, &stab, 1e-12, + &gate_index, Some(&noise_map), + )); + } + let t_sparse = start.elapsed(); + + // Verify exact match + for (i, (&pw, &ps)) in p_windowed.iter().zip(p_sparse.iter()).enumerate() { + assert!((pw - ps).abs() < 1e-12, + "d={d} det{i}: windowed={pw:.15} vs sparse={ps:.15}, diff={:.2e}", + (pw - ps).abs()); + } + + let speedup = t_windowed.as_secs_f64() / t_sparse.as_secs_f64(); + eprintln!("{d:>4} {num_rounds:>6} {:>8} {:>8} {num_detectors:>6} {:>12.2} {:>12.2} {speedup:>8.1}x", + expanded.gates.len(), expanded.num_qubits, + t_windowed.as_secs_f64() * 1000.0, + t_sparse.as_secs_f64() * 1000.0); + } + + // --- 2D grid codes (high sparsity at large d) --- + // Each Z-stabilizer checks a plaquette of 4 data qubits using 1 ancilla. + // Detectors are local: each touches only 1 ancilla + 4 data qubits. + // At d=7: 49 data qubits, 24 Z-stab ancillas, ~500+ expanded gates. + // A detector touches ~10 qubits out of ~100+ — high sparsity. + eprintln!("\n--- 2D grid codes (surface-code-like) ---"); + eprintln!("{:>4} {:>6} {:>8} {:>8} {:>6} {:>12} {:>12} {:>8}", + "d", "rnds", "gates", "exp_q", "n_det", "windowed_ms", "sparse_ms", "speedup"); + + for &(d, num_rounds) in &[(3, 2), (5, 2), (7, 2), (9, 2), (7, 5), (9, 5)] { + // Build a d x d grid with Z-plaquette stabilizers. + // Data qubits: (r, c) for r in 0..d, c in 0..d → index r*d + c + // Z-ancillas: one per plaquette, (d-1)*(d-1) total + let num_data = d * d; + let num_ancilla = (d - 1) * (d - 1); + let num_qubits = num_data + num_ancilla; + let anc_start = num_data; + + let mut gates = Vec::new(); + for q in 0..num_qubits { + gates.push(gate(GateType::PZ, &[q])); + } + + for round in 0..num_rounds { + // Z-stabilizer syndrome: CX(data, anc) for each of 4 data qubits + // Plaquette (r, c) has corners at data qubits: + // (r, c), (r, c+1), (r+1, c), (r+1, c+1) + for r in 0..(d - 1) { + for c in 0..(d - 1) { + let anc = anc_start + r * (d - 1) + c; + let d00 = r * d + c; + let d01 = r * d + c + 1; + let d10 = (r + 1) * d + c; + let d11 = (r + 1) * d + c + 1; + gates.push(gate(GateType::CX, &[d00, anc])); + gates.push(gate(GateType::CX, &[d01, anc])); + gates.push(gate(GateType::CX, &[d10, anc])); + gates.push(gate(GateType::CX, &[d11, anc])); + } + } + for i in 0..num_ancilla { + gates.push(gate(GateType::MZ, &[anc_start + i])); + } + if round < num_rounds - 1 { + for i in 0..num_ancilla { + gates.push(gate(GateType::PZ, &[anc_start + i])); + } + } + } + for q in 0..num_data { + gates.push(gate(GateType::MZ, &[q])); + } + + let expanded = crate::expand::expand_circuit(&gates); + let gate_index = crate::expand::GateIndex::build(&expanded.gates, expanded.num_qubits); + let noise_map = build_noise_map(&expanded.gates, &noise, &gate_index.expansion_gates); + + let init_gates: Vec = (0..num_qubits) + .map(|q| gate(GateType::PZ, &[q])) + .collect(); + let stab = crate::stabilizer::StabilizerGroup::from_circuit( + &init_gates, expanded.num_qubits, + ); + + // Build detectors: round-to-round comparison of each ancilla + let num_detectors = num_ancilla * (num_rounds - 1); + let mut detectors = Vec::new(); + for round in 0..(num_rounds - 1) { + for i in 0..num_ancilla { + let m1 = round * num_ancilla + i; + let m2 = (round + 1) * num_ancilla + i; + let aux1 = expanded.measurement_qubit[m1]; + let aux2 = expanded.measurement_qubit[m2]; + let det_bm = Bm::z(aux1).multiply(&Bm::z(aux2)); + detectors.push(det_bm); + } + } + + // Time windowed + let start = Instant::now(); + let mut p_windowed = Vec::new(); + for det in &detectors { + p_windowed.push(heisenberg_with_noise_map( + &expanded.gates, det, &noise_map, &stab, 1e-12, + )); + } + let t_windowed = start.elapsed(); + + // Time sparse + let start = Instant::now(); + let mut p_sparse = Vec::new(); + for det in &detectors { + p_sparse.push(heisenberg_sparse( + &expanded.gates, det, &noise, &stab, 1e-12, + &gate_index, Some(&noise_map), + )); + } + let t_sparse = start.elapsed(); + + // Verify exact match + for (i, (&pw, &ps)) in p_windowed.iter().zip(p_sparse.iter()).enumerate() { + assert!((pw - ps).abs() < 1e-12, + "grid d={d} det{i}: windowed={pw:.15} vs sparse={ps:.15}, diff={:.2e}", + (pw - ps).abs()); + } + + let speedup = t_windowed.as_secs_f64() / t_sparse.as_secs_f64(); + eprintln!("{d:>4} {num_rounds:>6} {:>8} {:>8} {num_detectors:>6} {:>12.2} {:>12.2} {speedup:>8.1}x", + expanded.gates.len(), expanded.num_qubits, + t_windowed.as_secs_f64() * 1000.0, + t_sparse.as_secs_f64() * 1000.0); + } + } +} diff --git a/exp/pecos-eeg/src/lib.rs b/exp/pecos-eeg/src/lib.rs new file mode 100644 index 000000000..0081580c0 --- /dev/null +++ b/exp/pecos-eeg/src/lib.rs @@ -0,0 +1,53 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Elementary Error Generator (EEG) analysis for coherent noise. +//! +//! Propagates error generators through Clifford circuits and produces +//! detector error probabilities at polynomial cost. Based on: +//! - Miller et al. arXiv:2504.15128 (simulation algorithm) +//! - Hines et al. arXiv:2603.18457 (DEM mapping) +//! +//! # Algorithm +//! +//! 1. Express noise as sparse EEG generators (H, S, C, A types) +//! 2. Propagate each generator forward through Clifford gates +//! 3. Combine via BCH formula (first order = sum) +//! 4. Classify by DEM event (which detectors each Pauli flips) +//! 5. Compute detection event probabilities + +pub mod builder; +pub mod circuit; +pub mod coherent_dem; +pub mod correlation_table; +pub mod dem_generator; +pub mod dem_mapping; +pub mod dem_simulator; +pub mod noise_characterization; +pub mod noise_compression; +pub mod eeg; +pub mod expand; +pub mod heisenberg; +pub mod noise; +pub mod propagate; +pub mod stabilizer; +pub mod strong_sim; + +/// Pauli bitmask type used throughout the EEG crate. +/// Pauli bitmask type used throughout the EEG crate. Uses SmallVec<[u64; 8]> +/// for 512 bits inline (zero allocation up to d=9 surface codes), with +/// automatic heap spillover for larger circuits. +pub type Bm = pecos_core::PauliBitmaskSmall; + +// Re-export key types for convenience +pub use dem_mapping::{BchOrder, EegConfig, HFormula}; +pub use noise::{NoiseInjection, NoiseSpec, UniformNoise}; diff --git a/exp/pecos-eeg/src/noise.rs b/exp/pecos-eeg/src/noise.rs new file mode 100644 index 000000000..6468db56b --- /dev/null +++ b/exp/pecos-eeg/src/noise.rs @@ -0,0 +1,185 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Noise model specification for EEG analysis. +//! +//! Defines the [`NoiseSpec`] trait for specifying how noise generators are +//! injected at each gate in the circuit. The built-in [`UniformNoise`] +//! applies the same rates to all gates of each type (matching the original +//! `NoiseModel`). Users can implement custom noise for per-gate control. + +use crate::Bm; +use crate::eeg::EegType; +use pecos_core::gate_type::GateType; + +/// A noise generator to inject at a specific point in the circuit. +#[derive(Clone, Debug)] +pub struct NoiseInjection { + /// EEG type of the generator. + pub eeg_type: EegType, + /// Primary Pauli label. + pub label: Bm, + /// Second label for C/A types. + pub label2: Option, + /// Rate (coefficient). + pub rate: f64, +} + +/// Trait for noise models that produce EEG generators at each gate. +/// +/// Implement this to specify arbitrary per-gate noise. The EEG analysis +/// calls `noise_after_gate` for each gate in the expanded circuit, +/// propagates the returned generators to the end, and accumulates them. +/// +/// The built-in [`UniformNoise`] applies the same rates to all gates of +/// each type. For per-gate or per-qubit noise, implement this trait +/// with a custom struct. +pub trait NoiseSpec: Send + Sync { + /// Return noise generators to inject after the gate at `gate_index`. + /// + /// The `qubits` are the qubit indices of the gate. For 2-qubit gates, + /// idle coherent noise is typically injected on both qubits. + /// + /// Return an empty vec for no noise at this gate. + fn noise_after_gate(&self, gate_index: usize, gate_type: GateType, qubits: &[usize]) -> Vec; +} + +/// Uniform noise model: same rates for all gates of each type. +/// +/// This is the original `NoiseModel` wrapped as a `NoiseSpec`. +#[derive(Clone, Debug)] +pub struct UniformNoise { + /// Coherent RZ angle (radians) on both qubits after each 2-qubit gate. + pub idle_rz: f64, + /// Single-qubit depolarizing probability. + pub p1: f64, + /// Two-qubit depolarizing probability. + pub p2: f64, + /// Measurement bit-flip probability. + pub p_meas: f64, + /// Preparation error probability. + pub p_prep: f64, +} + +impl UniformNoise { + #[must_use] + pub fn coherent_only(idle_rz: f64) -> Self { + Self { idle_rz, p1: 0.0, p2: 0.0, p_meas: 0.0, p_prep: 0.0 } + } + + #[must_use] + pub fn depolarizing(p: f64) -> Self { + Self { idle_rz: 0.0, p1: p, p2: p, p_meas: p, p_prep: p } + } + + #[must_use] + pub fn with_idle_rz(mut self, angle: f64) -> Self { + self.idle_rz = angle; + self + } +} + +impl NoiseSpec for UniformNoise { + fn noise_after_gate(&self, _gate_index: usize, gate_type: GateType, qubits: &[usize]) -> Vec { + let mut injections = Vec::new(); + + match gate_type { + // Two-qubit gates: idle RZ + depolarizing + GateType::CX | GateType::CZ | GateType::CY | GateType::SWAP + | GateType::SZZ | GateType::SZZdg + | GateType::SXX | GateType::SXXdg + | GateType::SYY | GateType::SYYdg => { + if self.idle_rz.abs() > 0.0 && qubits.len() >= 2 { + for &q in &qubits[..2] { + injections.push(NoiseInjection { + eeg_type: EegType::H, + label: Bm::z(q), + label2: None, + rate: self.idle_rz / 2.0, + }); + } + } + if self.p2 > 0.0 && qubits.len() >= 2 { + inject_depol_2q(qubits[0], qubits[1], self.p2, &mut injections); + } + } + + // Single-qubit Clifford: depolarizing + GateType::H | GateType::SZ | GateType::SZdg + | GateType::SX | GateType::SXdg | GateType::SY | GateType::SYdg + | GateType::X | GateType::Y | GateType::Z => { + if self.p1 > 0.0 && !qubits.is_empty() { + inject_depol_1q(qubits[0], self.p1, &mut injections); + } + } + + // Measurement error + GateType::MZ => { + if self.p_meas > 0.0 { + for &q in qubits { + injections.push(NoiseInjection { + eeg_type: EegType::S, + label: Bm::x(q), + label2: None, + rate: -self.p_meas, + }); + } + } + } + + // Preparation error + GateType::PZ => { + if self.p_prep > 0.0 { + for &q in qubits { + injections.push(NoiseInjection { + eeg_type: EegType::S, + label: Bm::x(q), + label2: None, + rate: -self.p_prep, + }); + } + } + } + + // Explicit RZ gate + GateType::RZ => { + // Note: RZ angle should be passed via gate.angles, not noise model. + // This case is handled separately in analyze_expanded. + } + + _ => {} + } + + injections + } +} + +fn inject_depol_1q(q: usize, prob: f64, out: &mut Vec) { + let rate = -prob / 3.0; + for pf in [Bm::x, Bm::y, Bm::z] { + out.push(NoiseInjection { + eeg_type: EegType::S, + label: pf(q), + label2: None, + rate, + }); + } +} + +fn inject_depol_2q(qa: usize, qb: usize, prob: f64, out: &mut Vec) { + let rate = -prob / 15.0; + let pfs = [Bm::x, Bm::y, Bm::z]; + for &pa in &pfs { + out.push(NoiseInjection { eeg_type: EegType::S, label: pa(qa), label2: None, rate }); + out.push(NoiseInjection { eeg_type: EegType::S, label: pa(qb), label2: None, rate }); + for &pb in &pfs { + out.push(NoiseInjection { + eeg_type: EegType::S, + label: pa(qa).multiply(&pb(qb)), + label2: None, + rate, + }); + } + } +} diff --git a/exp/pecos-eeg/src/noise_characterization.rs b/exp/pecos-eeg/src/noise_characterization.rs new file mode 100644 index 000000000..43b7d11c1 --- /dev/null +++ b/exp/pecos-eeg/src/noise_characterization.rs @@ -0,0 +1,258 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Unified noise characterization: correlations + mechanisms + DEM. +//! +//! Outputs use string labels ("D0", "D1", "L0") consistent with Stim format. +//! Includes detector/observable definitions mapping to MeasIds. + +use crate::correlation_table::compute_correlation_table; +use crate::coherent_dem::build_coherent_dem_exact; +use crate::dem_mapping::{DemEntry, DemEvent, Detector, Observable, format_dem}; +use crate::noise::NoiseSpec; +use crate::stabilizer::StabilizerGroup; +use pecos_core::Gate; + +/// A correlation entry with string labels. +#[derive(Debug, Clone)] +pub struct LabeledCorrelation { + /// Node labels: "D0", "D1", "L0", etc. + pub labels: Vec, + /// Joint probability. + pub probability: f64, +} + +/// A mechanism in the DEM with string labels. +#[derive(Debug, Clone)] +pub struct LabeledMechanism { + /// Detectors this mechanism flips: "D0", "D3", etc. + pub detectors: Vec, + /// Observables this mechanism flips: "L0", etc. + pub observables: Vec, + /// Fitted probability. + pub probability: f64, +} + +/// Definition of a detector or observable in terms of MeasIds. +#[derive(Debug, Clone)] +pub struct NodeDefinition { + /// Label: "D0", "L0", etc. + pub label: String, + /// MeasIds that XOR together to produce this node's value. + pub meas_ids: Vec, + /// Record offsets (negative, relative to end of measurement record). + pub records: Vec, +} + +/// Complete noise characterization. +#[derive(Debug, Clone)] +pub struct NoiseCharacterization { + /// Detector and observable definitions (label -> MeasIds). + pub definitions: Vec, + /// Exact k-body correlations with string labels. + pub correlations: Vec, + /// DEM mechanisms with string labels and fitted probabilities. + pub mechanisms: Vec, + /// Decomposable DEM entries with X/Z component info for MWPM decoders. + pub decomposable_entries: Vec, + /// Maximum correlation order computed. + pub max_order: usize, + /// Number of Heisenberg walks performed. + pub num_walks: usize, +} + +impl NoiseCharacterization { + /// Build from circuit + noise model. + /// + /// `noise` is used for exact Heisenberg correlation targets. + /// `structure_noise` (if provided) is used for DEM mechanism extraction — + /// useful when passing compressed noise for structure while keeping + /// original noise for exact targets. If `None`, uses `noise` for both. + pub fn build( + gates: &[Gate], + noise: &dyn NoiseSpec, + structure_noise: Option<&dyn NoiseSpec>, + detectors: &[Detector], + observables: &[Observable], + initial_stab: &StabilizerGroup, + num_qubits: usize, + max_order: usize, + prune_threshold: f64, + detector_meas_ids: &[(usize, Vec, Vec)], + observable_meas_ids: &[(usize, Vec, Vec)], + ) -> Self { + let mechanism_noise = structure_noise.unwrap_or(noise); + + // Correlation table (always uses exact noise) + let table = compute_correlation_table( + gates, noise, detectors, observables, initial_stab, + num_qubits, max_order, prune_threshold, + ); + + // DEM with fitted probabilities (uses mechanism noise for structure) + let num_dets = detectors.len(); + let mut marginals = vec![0.0_f64; num_dets]; + for det in detectors { + if let Some(&p) = table.rates.get(&vec![det.id]) { + if det.id < num_dets { marginals[det.id] = p; } + } + } + let pairwise: Vec<((usize, usize), f64)> = table.rates.iter() + .filter(|(k, _)| k.len() == 2) + .map(|(k, &v)| ((k[0], k[1]), v)) + .collect(); + let gate_index = crate::expand::GateIndex::build(gates, num_qubits); + let dem_entries = build_coherent_dem_exact( + gates, mechanism_noise, detectors, observables, &gate_index.expansion_gates, + &marginals, Some(&pairwise), + ); + let decomposable_entries = crate::coherent_dem::build_coherent_dem_exact_decomposable( + gates, mechanism_noise, detectors, observables, &gate_index.expansion_gates, + &marginals, Some(&pairwise), + ); + + // Build definitions + let mut definitions = Vec::new(); + for &(id, ref mids, ref recs) in detector_meas_ids { + definitions.push(NodeDefinition { + label: format!("D{id}"), + meas_ids: mids.clone(), + records: recs.clone(), + }); + } + for &(id, ref mids, ref recs) in observable_meas_ids { + definitions.push(NodeDefinition { + label: format!("L{id}"), + meas_ids: mids.clone(), + records: recs.clone(), + }); + } + + // Build labeled correlations from detector rates + let mut correlations = Vec::new(); + for (key, &prob) in &table.rates { + if prob > 1e-15 { + let labels: Vec = key.iter().map(|&d| format!("D{d}")).collect(); + correlations.push(LabeledCorrelation { labels, probability: prob }); + } + } + // Add observable correlations + for ((det_ids, obs_id), &prob) in &table.observable_rates { + if prob > 1e-15 { + let mut labels: Vec = det_ids.iter().map(|&d| format!("D{d}")).collect(); + labels.push(format!("L{obs_id}")); + correlations.push(LabeledCorrelation { labels, probability: prob }); + } + } + + // Build labeled mechanisms + let mechanisms: Vec = dem_entries.iter() + .filter(|e| e.probability > 1e-15) + .map(|e| LabeledMechanism { + detectors: e.event.detectors.iter().map(|&d| format!("D{d}")).collect(), + observables: e.event.observables.iter().map(|&o| format!("L{o}")).collect(), + probability: e.probability, + }) + .collect(); + + NoiseCharacterization { + definitions, + correlations, + mechanisms, + decomposable_entries, + max_order: table.max_order, + num_walks: table.num_walks, + } + } + + /// Output as Stim DEM string. + #[must_use] + pub fn to_dem_string(&self) -> String { + let entries: Vec = self.mechanisms.iter() + .map(|m| { + let dets: Vec = m.detectors.iter() + .map(|s| s[1..].parse().unwrap_or(0)) + .collect(); + let obs: Vec = m.observables.iter() + .map(|s| s[1..].parse().unwrap_or(0)) + .collect(); + DemEntry { + event: DemEvent { + detectors: dets.into_iter().collect(), + observables: obs.into_iter().collect(), + }, + probability: m.probability, + } + }) + .collect(); + format_dem(&entries) + } + + /// Output as decomposed (graphlike) DEM string for MWPM decoders. + /// + /// Uses X/Z Pauli-aware decomposition from the backward mechanism + /// extraction. Hyperedges are split into X ^ Z components. + #[must_use] + pub fn to_dem_string_decomposed(&self) -> String { + crate::dem_mapping::format_dem_decomposed(&self.decomposable_entries) + } + + /// Serialize to JSON. + #[must_use] + pub fn to_json(&self) -> String { + let mut j = String::from("{\n"); + + j.push_str(&format!(" \"max_order\": {},\n", self.max_order)); + j.push_str(&format!(" \"num_walks\": {},\n", self.num_walks)); + + // Definitions + j.push_str(" \"definitions\": [\n"); + for (i, def) in self.definitions.iter().enumerate() { + j.push_str(&format!( + " {{\"label\": \"{}\", \"meas_ids\": {:?}, \"records\": {:?}}}", + def.label, def.meas_ids, def.records + )); + if i + 1 < self.definitions.len() { j.push(','); } + j.push('\n'); + } + j.push_str(" ],\n"); + + // Correlations + j.push_str(" \"correlations\": [\n"); + for (i, c) in self.correlations.iter().enumerate() { + j.push_str(&format!( + " {{\"nodes\": {:?}, \"probability\": {:.10e}}}", + c.labels, c.probability + )); + if i + 1 < self.correlations.len() { j.push(','); } + j.push('\n'); + } + j.push_str(" ],\n"); + + // Mechanisms + j.push_str(" \"mechanisms\": [\n"); + for (i, m) in self.mechanisms.iter().enumerate() { + let mut nodes: Vec<&str> = m.detectors.iter().map(|s| s.as_str()).collect(); + nodes.extend(m.observables.iter().map(|s| s.as_str())); + j.push_str(&format!( + " {{\"nodes\": {:?}, \"probability\": {:.10e}}}", + nodes, m.probability + )); + if i + 1 < self.mechanisms.len() { j.push(','); } + j.push('\n'); + } + j.push_str(" ]\n"); + + j.push('}'); + j + } +} diff --git a/exp/pecos-eeg/src/noise_compression.rs b/exp/pecos-eeg/src/noise_compression.rs new file mode 100644 index 000000000..25cfc970b --- /dev/null +++ b/exp/pecos-eeg/src/noise_compression.rs @@ -0,0 +1,330 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Round-boundary noise compression. +//! +//! Propagates mid-round fault locations to round boundaries, producing +//! effective noise sources with accumulated probabilities/amplitudes. +//! +//! For stochastic Pauli noise: exact (Paulis compose deterministically). +//! For coherent noise: accumulates within-round angles exactly. +//! +//! This dramatically reduces the number of noise sources: +//! ~60 mid-round faults per round → ~17 boundary faults (9 data + 8 meas). + +use crate::Bm; +use crate::eeg::EegType; +use crate::noise::{NoiseInjection, NoiseSpec}; +use pecos_core::gate_type::GateType; +use pecos_core::Gate; +use smallvec::SmallVec; +use std::collections::BTreeMap; + +/// An effective noise source at a round boundary. +#[derive(Debug, Clone)] +pub struct BoundaryNoise { + /// The effective Pauli label at the boundary. + pub label: Bm, + /// EEG type (H or S). + pub eeg_type: EegType, + /// Accumulated rate (S-type) or amplitude (H-type). + pub value: f64, + /// Gate index of the boundary (for position tracking). + pub boundary_gate: usize, +} + +/// Result of noise compression. +pub struct CompressedNoise { + /// Effective noise sources at round boundaries. + pub boundary_sources: Vec, + /// Measurement noise (kept as-is, not compressed). + pub measurement_sources: Vec<(usize, NoiseInjection)>, + /// Preparation noise (kept as-is). + pub preparation_sources: Vec<(usize, NoiseInjection)>, + /// Number of original noise sources before compression. + pub original_count: usize, + /// Number of compressed sources. + pub compressed_count: usize, +} + +/// Compress mid-round noise to round boundaries. +/// +/// Identifies rounds (PZ/QAlloc → gates → MZ), propagates each +/// mid-round noise source's Pauli label forward through remaining +/// gates to the next boundary, and accumulates. +/// +/// Gate noise (p1, p2) is compressed. Measurement (p_meas) and +/// preparation (p_prep) noise is kept at its original position. +pub fn compress_noise_to_boundaries( + gates: &[Gate], + noise: &dyn NoiseSpec, + expansion_gates: &[bool], +) -> CompressedNoise { + let n_gates = gates.len(); + let max_qubit = gates.iter() + .flat_map(|g| g.qubits.iter()) + .map(|q| q.index()) + .max() + .unwrap_or(0); + + // Step 1: Collect all noise sources + let mut all_noise: Vec<(usize, NoiseInjection)> = Vec::new(); + for (gate_idx, gate) in gates.iter().enumerate() { + if gate_idx < expansion_gates.len() && expansion_gates[gate_idx] { + continue; + } + let qubits: SmallVec<[usize; 4]> = gate.qubits.iter().map(|q| q.index()).collect(); + let injections = noise.noise_after_gate(gate_idx, gate.gate_type, &qubits); + for inj in injections { + all_noise.push((gate_idx, inj)); + } + } + + let original_count = all_noise.len(); + + // Step 2: Identify round boundaries. + // A boundary is an MZ gate (end of round) or PZ/QAlloc (start of round). + // We propagate gate noise forward to the NEXT MZ on the same qubit. + let mut measurement_sources = Vec::new(); + let mut preparation_sources = Vec::new(); + let mut gate_noise: Vec<(usize, NoiseInjection)> = Vec::new(); + + for (gate_idx, inj) in &all_noise { + let gate = &gates[*gate_idx]; + match gate.gate_type { + GateType::MZ | GateType::MeasureFree => { + measurement_sources.push((*gate_idx, inj.clone())); + } + GateType::PZ | GateType::QAlloc => { + preparation_sources.push((*gate_idx, inj.clone())); + } + _ => { + gate_noise.push((*gate_idx, inj.clone())); + } + } + } + + // Step 3: For each gate noise source, propagate its label forward + // through subsequent gates until we hit a round boundary (MZ or PZ). + // Group by (boundary_gate, effective_label, eeg_type). + let mut boundary_groups: BTreeMap<(usize, Bm, EegType), f64> = BTreeMap::new(); + + for (gate_idx, inj) in &gate_noise { + let mut label = inj.label.clone(); + + // Propagate forward through subsequent gates until we hit a boundary. + // The effective noise lives just BEFORE the boundary gate, so we + // inject it "after" the last non-boundary gate before it. + let mut inject_at = *gate_idx; // default: stay at original position + for g in (*gate_idx + 1)..n_gates { + match gates[g].gate_type { + GateType::MZ | GateType::MeasureFree | GateType::PZ | GateType::QAlloc => { + let noise_qubits: Vec = label_qubits(&label, max_qubit); + let boundary_qubits: Vec = gates[g].qubits.iter() + .map(|q| q.index()).collect(); + if noise_qubits.iter().any(|q| boundary_qubits.contains(q)) { + // Inject at the gate just before the boundary + // (inject_at was set to g-1 by the last non-boundary gate) + break; + } + } + _ => { + // Propagate the label forward through this gate + forward_conjugate_label(&mut label, &gates[g]); + // Only update inject_at for non-expansion gates. + // Expansion gates are invisible to the noise map — + // injecting there would be silently dropped. + if !(g < expansion_gates.len() && expansion_gates[g]) { + inject_at = g; + } + } + } + } + + let key = (inject_at, label.clone(), inj.eeg_type); + *boundary_groups.entry(key).or_insert(0.0) += inj.rate; + } + + // Step 4: Convert groups to boundary noise sources + let boundary_sources: Vec = boundary_groups + .into_iter() + .filter(|(_, value)| value.abs() > 1e-20) + .map(|((boundary_gate, label, eeg_type), value)| { + BoundaryNoise { + label, + eeg_type, + value, + boundary_gate, + } + }) + .collect(); + + let compressed_count = boundary_sources.len() + + measurement_sources.len() + + preparation_sources.len(); + + CompressedNoise { + boundary_sources, + measurement_sources, + preparation_sources, + original_count, + compressed_count, + } +} + +/// Extract qubits that a Pauli label acts on (up to max_qubit). +fn label_qubits(label: &Bm, max_qubit: usize) -> Vec { + let mut qubits = Vec::new(); + for q in 0..=max_qubit { + if label.has_x(q) || label.has_z(q) { + qubits.push(q); + } + } + qubits +} + +/// Forward-conjugate a Pauli label through a gate (Schrödinger picture). +/// +/// This is the FORWARD direction: P → U P U†. +/// For non-self-adjoint gates, we use the forward conjugation directly +/// (not the adjoint swap used in backward walks). +fn forward_conjugate_label(label: &mut Bm, gate: &Gate) { + use crate::heisenberg::{SparsePauli, sparse_conjugate}; + + match gate.gate_type { + GateType::PZ | GateType::QAlloc | GateType::QFree + | GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked + | GateType::I | GateType::Idle => return, + _ => {} + } + + // sparse_conjugate uses backward (Heisenberg) convention. + // For forward propagation of a Pauli label, we need U P U†. + // For self-adjoint gates: same as backward. + // For non-self-adjoint: we need to swap the gate to its adjoint + // before calling sparse_conjugate (which already swaps for backward). + // Two swaps cancel → just call sparse_conjugate on the adjoint gate. + // + // Simpler: for forward, swap S↔Sdg BEFORE calling sparse_conjugate + // (which swaps again for backward), giving net: forward conjugation. + // + // Actually, sparse_conjugate applies backward convention (swaps non-self-adjoint). + // For forward conjugation, we need the opposite swap. + // Forward of SZ: SZ P SZdg → same as backward of SZdg. + // So forward_conjugate(P, SZ) = sparse_conjugate(P, SZdg). + // + // For self-adjoint gates: no difference. + // For non-self-adjoint: pass the adjoint gate type. + + let adjoint_type = match gate.gate_type { + GateType::SZ => GateType::SZdg, + GateType::SZdg => GateType::SZ, + GateType::SX => GateType::SXdg, + GateType::SXdg => GateType::SX, + GateType::SY => GateType::SYdg, + GateType::SYdg => GateType::SY, + GateType::SZZ => GateType::SZZdg, + GateType::SZZdg => GateType::SZZ, + GateType::SXX => GateType::SXXdg, + GateType::SXXdg => GateType::SXX, + GateType::SYY => GateType::SYYdg, + GateType::SYYdg => GateType::SYY, + other => other, // self-adjoint + }; + + // Build a temporary gate with the adjoint type + let adj_gate = Gate { + gate_type: adjoint_type, + qubits: gate.qubits.clone(), + angles: gate.angles.clone(), + params: gate.params.clone(), + meas_ids: gate.meas_ids.clone(), + }; + + let mut sp = SparsePauli::from_bm(label); + let _sign = sparse_conjugate(&mut sp, &adj_gate); + *label = sp.to_bm(); +} + +/// A `NoiseSpec` adapter that returns compressed boundary noise. +/// +/// Call `noise_after_gate()` on each gate just like the original noise model, +/// but mid-round gate noise is empty — all accumulated at boundaries. +pub struct CompressedNoiseSpec { + /// Gate index → noise injections at that gate. + gate_noise: BTreeMap>, +} + +impl CompressedNoiseSpec { + /// Build from compressed noise result. + #[must_use] + pub fn from_compressed(compressed: &CompressedNoise) -> Self { + let mut gate_noise: BTreeMap> = BTreeMap::new(); + + // Boundary sources → noise at boundary gate + for bn in &compressed.boundary_sources { + gate_noise.entry(bn.boundary_gate).or_default().push(NoiseInjection { + eeg_type: bn.eeg_type, + label: bn.label.clone(), + label2: None, + rate: bn.value, + }); + } + + // Measurement and prep sources stay at original positions + for (gate_idx, inj) in &compressed.measurement_sources { + gate_noise.entry(*gate_idx).or_default().push(inj.clone()); + } + for (gate_idx, inj) in &compressed.preparation_sources { + gate_noise.entry(*gate_idx).or_default().push(inj.clone()); + } + + Self { gate_noise } + } +} + +impl NoiseSpec for CompressedNoiseSpec { + fn noise_after_gate( + &self, + gate_index: usize, + _gate_type: GateType, + _qubits: &[usize], + ) -> Vec { + self.gate_noise.get(&gate_index).cloned().unwrap_or_default() + } +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::noise::UniformNoise; + + #[test] + fn test_compression_reduces_count() { + // Simple circuit: PZ(0,1), CX(0,1), H(1), CX(0,1), MZ(0,1) + let gates = vec![ + crate::expand::make_gate(GateType::PZ, &[0]), + crate::expand::make_gate(GateType::PZ, &[1]), + crate::expand::make_gate(GateType::CX, &[0, 1]), + crate::expand::make_gate(GateType::H, &[1]), + crate::expand::make_gate(GateType::CX, &[0, 1]), + crate::expand::make_gate(GateType::MZ, &[0]), + crate::expand::make_gate(GateType::MZ, &[1]), + ]; + let noise = UniformNoise { idle_rz: 0.0, p1: 0.001, p2: 0.01, p_meas: 0.01, p_prep: 0.01 }; + let expansion = vec![false; gates.len()]; + + let result = compress_noise_to_boundaries(&gates, &noise, &expansion); + assert!(result.compressed_count < result.original_count, + "compressed {} should be < original {}", result.compressed_count, result.original_count); + } +} diff --git a/exp/pecos-eeg/src/propagate.rs b/exp/pecos-eeg/src/propagate.rs new file mode 100644 index 000000000..23c70ef17 --- /dev/null +++ b/exp/pecos-eeg/src/propagate.rs @@ -0,0 +1,11 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Re-export Clifford conjugation from pecos-core. + +pub use pecos_core::pauli::pauli_bitmask::{ + conjugate_cx, conjugate_cy, conjugate_cz, conjugate_h, conjugate_swap, conjugate_sx, + conjugate_sxdg, conjugate_sy, conjugate_sydg, conjugate_sz, conjugate_szdg, conjugate_x, + conjugate_y, conjugate_z, +}; diff --git a/exp/pecos-eeg/src/stabilizer.rs b/exp/pecos-eeg/src/stabilizer.rs new file mode 100644 index 000000000..5ac0d292a --- /dev/null +++ b/exp/pecos-eeg/src/stabilizer.rs @@ -0,0 +1,209 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Track the stabilizer group of the noiseless output state using SparseStab. + +use crate::Bm; +use pecos_core::gate_type::GateType; +use pecos_core::pauli::pauli_bitmask::BitmaskStorage; +use pecos_core::{Gate, QuarterPhase, QubitId}; +use pecos_simulators::{CliffordGateable, SparseStab}; + +/// The stabilizer group, tracked via SparseStab. +/// +/// Keeps the full SparseStab (stabilizers + destabilizers) so we can +/// determine the exact sign (+1 or -1) of stabilizer group elements. +pub struct StabilizerGroup { + sim: SparseStab, +} + +impl StabilizerGroup { + /// Run the noiseless circuit on SparseStab. + pub fn from_circuit(gates: &[Gate], num_qubits: usize) -> Self { + let mut sim = SparseStab::with_seed(num_qubits, 0); + + for gate in gates { + let qubits: Vec = gate.qubits.iter().copied().collect(); + if qubits.is_empty() { + continue; + } + + match gate.gate_type { + GateType::PZ | GateType::QAlloc => { + for &q in &qubits { sim.pz(&[q]); } + } + GateType::H => { sim.h(&qubits); } + GateType::SZ => { sim.sz(&qubits); } + GateType::SZdg => { sim.szdg(&qubits); } + GateType::SX => { sim.sx(&qubits); } + GateType::SXdg => { sim.sxdg(&qubits); } + GateType::SY => { sim.sy(&qubits); } + GateType::SYdg => { sim.sydg(&qubits); } + GateType::X => { sim.x(&qubits); } + GateType::Y => { sim.y(&qubits); } + GateType::Z => { sim.z(&qubits); } + GateType::CX => { + if qubits.len() >= 2 { + sim.cx(&[(qubits[0], qubits[1])]); + } + } + GateType::CY => { + if qubits.len() >= 2 { + sim.cy(&[(qubits[0], qubits[1])]); + } + } + GateType::CZ => { + if qubits.len() >= 2 { + sim.cz(&[(qubits[0], qubits[1])]); + } + } + GateType::SWAP => { + if qubits.len() >= 2 { + sim.swap(&[(qubits[0], qubits[1])]); + } + } + GateType::MZ => { + sim.mz(&qubits); + } + _ => {} + } + } + + Self { sim } + } + + /// Check if Pauli P is in the stabilizer group and return its sign. + /// + /// Returns: + /// - `Some(true)` if P is a +1 stabilizer + /// - `Some(false)` if P is a -1 stabilizer (anti-stabilizer) + /// - `None` if P is not in the stabilizer group + pub fn is_stabilizer(&self, p: &Bm) -> Option { + if p.is_identity() { + return Some(true); + } + + let mut x_positions = Vec::new(); + let mut z_positions = Vec::new(); + let mut num_ys = 0usize; + + let max_q = match (p.x_bits.highest_set_bit(), p.z_bits.highest_set_bit()) { + (None, None) => return Some(true), + (Some(a), None) | (None, Some(a)) => a + 1, + (Some(a), Some(b)) => a.max(b) + 1, + }; + + for q in 0..max_q { + let has_x = p.has_x(q); + let has_z = p.has_z(q); + if has_x { x_positions.push(q); } + if has_z { z_positions.push(q); } + if has_x && has_z { num_ys += 1; } + } + + let stabs = self.sim.stabs(); + let destabs = self.sim.destabs(); + let phase = stabs.find_pauli_sign(destabs, x_positions, z_positions, num_ys)?; + + match phase { + QuarterPhase::PlusOne => Some(true), + QuarterPhase::MinusOne => Some(false), + _ => None, + } + } +} + +#[cfg(test)] +mod tests { + use super::*; + use pecos_core::{GateAngles, GateParams, GateQubits}; + + fn gate(gt: GateType, qubits: &[usize]) -> Gate { + Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), + } + } + + #[test] + fn test_identity_circuit() { + let stabs = StabilizerGroup::from_circuit(&[], 1); + assert_eq!(stabs.is_stabilizer(&Bm::z(0)), Some(true)); + assert_eq!(stabs.is_stabilizer(&Bm::x(0)), None); + } + + #[test] + fn test_h_circuit() { + let gates = vec![gate(GateType::H, &[0])]; + let stabs = StabilizerGroup::from_circuit(&gates, 1); + assert_eq!(stabs.is_stabilizer(&Bm::x(0)), Some(true)); + assert_eq!(stabs.is_stabilizer(&Bm::z(0)), None); + } + + #[test] + fn test_bell_state() { + let gates = vec![ + gate(GateType::H, &[0]), + gate(GateType::CX, &[0, 1]), + ]; + let stabs = StabilizerGroup::from_circuit(&gates, 2); + assert_eq!(stabs.is_stabilizer(&Bm::x(0).multiply(&Bm::x(1))), Some(true)); + assert_eq!(stabs.is_stabilizer(&Bm::z(0).multiply(&Bm::z(1))), Some(true)); + } + + #[test] + fn test_x0x1_after_syndrome_extraction() { + let gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[4]), + gate(GateType::H, &[4]), + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[4, 0]), + gate(GateType::H, &[4]), + gate(GateType::MZ, &[4]), + gate(GateType::PZ, &[4]), + ]; + let stabs = StabilizerGroup::from_circuit(&gates, 5); + + let x0x1 = Bm::x(0).multiply(&Bm::x(1)); + assert_eq!(stabs.is_stabilizer(&x0x1), Some(true), + "X0*X1 should be stabilizer after syndrome extraction with MZ projection"); + } + + #[test] + fn test_anti_stabilizer() { + // After PZ, Z is +1 stabilizer. -Z should be anti-stabilizer. + // But -Z isn't a Pauli label in our system (no phase in Bm). + // Instead, apply X to flip the state to |1>, then Z has eigenvalue -1. + let gates = vec![gate(GateType::X, &[0])]; + let stabs = StabilizerGroup::from_circuit(&gates, 1); + // Initial state is |0>, X takes it to |1>. + // Z|1> = -|1>, so Z is a -1 stabilizer. + assert_eq!(stabs.is_stabilizer(&Bm::z(0)), Some(false), + "Z should be -1 stabilizer for |1> state"); + } + + #[test] + fn test_sign_bell_minus() { + // |Phi-> = (|00> - |11>)/sqrt(2) = CX H X |00> + // X flips to |10>, H gives |−0>, CX gives |Phi-> + // Stabilizers: -XX, +ZZ + let gates = vec![ + gate(GateType::X, &[0]), + gate(GateType::H, &[0]), + gate(GateType::CX, &[0, 1]), + ]; + let stabs = StabilizerGroup::from_circuit(&gates, 2); + // XX should be -1 stabilizer (the minus Bell state) + assert_eq!(stabs.is_stabilizer(&Bm::x(0).multiply(&Bm::x(1))), Some(false), + "XX should be -1 stabilizer for |Phi->"); + // ZZ should be +1 stabilizer + assert_eq!(stabs.is_stabilizer(&Bm::z(0).multiply(&Bm::z(1))), Some(true), + "ZZ should be +1 stabilizer for |Phi->"); + } +} diff --git a/exp/pecos-eeg/src/strong_sim.rs b/exp/pecos-eeg/src/strong_sim.rs new file mode 100644 index 000000000..805518a83 --- /dev/null +++ b/exp/pecos-eeg/src/strong_sim.rs @@ -0,0 +1,625 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Approximate strong simulation using EEG generators. +//! +//! Computes approximate outcome probabilities p̃_x for arbitrary bit strings x, +//! using the first-order Taylor expansion from Miller et al. (Eq. 17): +//! +//! p̃_x = p_x + (1/2^ζ) Σ_G α(ψ,G,x) ε_G + O(ε²) +//! +//! where α(ψ,G,x) = 2^ζ Tr(|x⟩⟨x| G[|ψ⟩⟨ψ|]) encodes how each generator +//! affects the probability of outcome x. +//! +//! At first order (l=1), only S-type generators contribute (H-type contributes +//! at second order). The S-type α is: +//! α(x, S_P, ψ) = [x⊕a ∈ support(ψ)] - [x ∈ support(ψ)] +//! where a is the X-component of P. + +use crate::Bm; +use crate::circuit::PropagatedEeg; +use crate::eeg::EegType; +use pecos_core::pauli::pauli_bitmask::BitmaskStorage; + +/// Result of approximate strong simulation for a specific outcome. +#[derive(Clone, Debug)] +pub struct OutcomeProbability { + /// Noiseless probability p_x = |⟨x|ψ⟩|². + pub noiseless: f64, + /// First-order S-type correction. + pub s_correction: f64, + /// Second-order H·H correction (via C-type α). + pub h_correction: f64, + /// Total approximate probability: noiseless + corrections. + pub total: f64, +} + +/// Compute the approximate probability of outcome x at first order. +/// +/// The outcome is a bit string (true = |1⟩, false = |0⟩) for each measured qubit. +/// The generators should be propagated to the end of the expanded circuit. +/// +/// At first order, only S-type generators contribute: +/// α(x, S_P, ψ) = [x⊕a ∈ support] - [x ∈ support] +/// where a is the X-component of P and "support" is the set of computational +/// basis states with nonzero amplitude in |ψ⟩. +/// +/// For a stabilizer state |ψ⟩ on n qubits: x is in the support iff +/// all stabilizer generators have eigenvalue +1 on |x⟩. +/// +/// # Arguments +/// * `generators` - Propagated EEG generators at end of circuit +/// * `outcome` - Bit string x (one bool per qubit) +/// * `stabilizers` - Stabilizer generators of |ψ⟩ as Bm +/// +/// # Limitations +/// Currently computes first-order (S-type) corrections only. H-type +/// corrections require second-order computation with phase tracking. +pub fn outcome_probability( + generators: &[PropagatedEeg], + outcome: &[bool], + stabilizers: &[Bm], +) -> OutcomeProbability { + let n = outcome.len(); + + // Check if x is in the support of |ψ⟩. + // x ∈ support iff ⟨x|S|x⟩ = +1 for all stabilizer generators S. + let x_in_support = is_in_support(outcome, stabilizers); + + // Noiseless probability: 1/2^ζ if in support, 0 otherwise. + // ζ = n - rank(stabilizer group restricted to Z-diagonal). + // For a pure state: ζ = 0 (deterministic), p_x = 0 or 1. + // For a projected state: ζ > 0, p_x = 1/2^ζ. + let zeta = compute_zeta(n, stabilizers); + let noiseless = if x_in_support { 1.0 / (1u64 << zeta) as f64 } else { 0.0 }; + + // First-order S-type corrections: α(x, S_P, ψ) = [x⊕a ∈ support] - [x ∈ support] + let mut s_correction = 0.0; + let scale = if zeta > 0 { 1.0 / (1u64 << zeta) as f64 } else { 1.0 }; + + for g in generators { + if g.eeg_type != EegType::S { + continue; + } + + let x_flipped = flip_outcome(outcome, &g.label); + let flipped_in_support = is_in_support(&x_flipped, stabilizers); + + let alpha = (if flipped_in_support { 1.0 } else { 0.0 }) + - (if x_in_support { 1.0 } else { 0.0 }); + + s_correction += scale * alpha * g.coeff; + } + + // Second-order H·H corrections using α(x, C_{P,P'}, ψ). + // (1/2) Σ_{P,P'} h_P h_{P'} α(x, C_{P,P'}, ψ) + // + // For commuting P,P': α(C) = 2 Re(Φ(P,P')) - 2 Re(Φ(PP',I)) + // For anticommuting P,P': α(C) = 2 Re(Φ(P,P')) (since {P,P'}=0 → Φ(PP',I) cancels) + // + // Extract stabilizer phases for Φ computation. + let stab_phases: Vec = stabilizers.iter() + .map(|_| false) // Default: all +1 stabilizers (sign info not available from Bm) + .collect(); + + let h_gens: Vec<_> = generators.iter() + .filter(|g| g.eeg_type == EegType::H) + .collect(); + + let mut h_correction = 0.0; + for j in 0..h_gens.len() { + for k in 0..h_gens.len() { + let h_j = h_gens[j].coeff; + let h_k = h_gens[k].coeff; + let p = &h_gens[j].label; + let q = &h_gens[k].label; + + // α(x, C_{P,Q}, ψ) for commuting P,Q: + // = 2 Re(Φ(P,Q)) - 2 Re(Φ(PQ,I)) + let phi_pq = compute_phi(p, q, outcome, stabilizers, &stab_phases); + let pq = p.multiply(q); + let identity = Bm::default(); + let phi_pq_i = compute_phi(&pq, &identity, outcome, stabilizers, &stab_phases); + + let alpha = if p.commutes_with(q) { + 2.0 * phi_pq.0 - 2.0 * phi_pq_i.0 + } else { + // Anticommuting: α(C) = 2 Re(Φ(P,Q)) + 2.0 * phi_pq.0 + }; + + // (1/2) h_j h_k α + h_correction += scale * 0.5 * h_j * h_k * alpha; + } + } + + // First-order C and A type corrections (if any exist directly in generators). + let mut ca_correction = 0.0; + for g in generators { + match g.eeg_type { + EegType::C => { + if let Some(ref q_label) = g.label2 { + // α(x, C_{P,Q}) = 2 Re(Φ(P,Q)) - Re(Φ(PQ,I) + Φ(QP,I)) + let phi_pq = compute_phi(&g.label, q_label, outcome, stabilizers, &stab_phases); + let pq = g.label.multiply(q_label); + let qp = q_label.multiply(&g.label); + let phi_pq_i = compute_phi(&pq, &Bm::default(), outcome, stabilizers, &stab_phases); + let phi_qp_i = compute_phi(&qp, &Bm::default(), outcome, stabilizers, &stab_phases); + let alpha = 2.0 * phi_pq.0 - (phi_pq_i.0 + phi_qp_i.0); + ca_correction += scale * g.coeff * alpha; + } + } + EegType::A => { + if let Some(ref q_label) = g.label2 { + // α(x, A_{P,Q}) = 2 Im(Φ(Q,P)) + Im(Φ(QP,I) - Φ(PQ,I)) + let phi_qp = compute_phi(q_label, &g.label, outcome, stabilizers, &stab_phases); + let qp = q_label.multiply(&g.label); + let pq = g.label.multiply(q_label); + let phi_qp_i = compute_phi(&qp, &Bm::default(), outcome, stabilizers, &stab_phases); + let phi_pq_i = compute_phi(&pq, &Bm::default(), outcome, stabilizers, &stab_phases); + let alpha = 2.0 * phi_qp.1 + (phi_qp_i.1 - phi_pq_i.1); + ca_correction += scale * g.coeff * alpha; + } + } + _ => {} + } + } + + let total = (noiseless + s_correction + h_correction + ca_correction).max(0.0).min(1.0); + + OutcomeProbability { + noiseless, + s_correction, + h_correction, + total, + } +} + +/// Compute Φ_{ψ,x}(P,Q) = 2^ζ ⟨x|P|ψ⟩⟨ψ|Q|x⟩ for stabilizer states. +/// +/// Returns a complex number as (real, imag). Result is in {0, ±1, ±i}. +/// +/// Uses: Φ(P,Q) = phase(P·S_0·Q) · (-1)^{z_{PS_0Q}·x} when conditions met. +/// S_0 is any stabilizer with x_part = x_P ⊕ x_Q. +fn compute_phi( + p: &Bm, + q: &Bm, + outcome: &[bool], + stabilizers: &[Bm], + stabilizer_phases: &[bool], // true = -1 sign (minus stabilizer) +) -> (f64, f64) { + // ⟨x|P|ψ⟩ is nonzero iff x⊕a_P is in the support of |ψ⟩. + // ⟨ψ|Q|x⟩ is nonzero iff x⊕a_Q is in the support. + // Both must hold for Φ to be nonzero. + let x_flip_p = flip_outcome(outcome, p); + if !is_in_support(&x_flip_p, stabilizers) { + return (0.0, 0.0); + } + let x_flip_q = flip_outcome(outcome, q); + if !is_in_support(&x_flip_q, stabilizers) { + return (0.0, 0.0); + } + + // Target X-pattern for S_0: x_P ⊕ x_Q + let target_x = p.multiply(q); // product has x_bits = p.x XOR q.x (and z, but we only use x) + + // Find a subset of generators whose X-parts XOR to target_x.x_bits + let n = stabilizers.len(); + + // Work with full Bm for GF2 ops (only X-part matters) + let mut row_x: Vec = stabilizers.iter() + .map(|s| Bm { x_bits: s.x_bits.clone(), z_bits: Default::default() }) + .collect(); + + let mut selected = vec![false; n]; + let mut target = Bm { x_bits: target_x.x_bits.clone(), z_bits: Default::default() }; + + // GF(2) greedy elimination + for bit in 0..outcome.len() { + if !target.x_bits.get_bit(bit) { + continue; + } + let found = row_x.iter().enumerate().find(|(_, r)| r.x_bits.get_bit(bit)); + if let Some((row_idx, _)) = found { + // Find the original stabilizer index for this row + // (rows may have been XOR-modified but indices track the original) + selected[row_idx] = true; + let pivot = row_x[row_idx].clone(); + target = target.multiply(&pivot); + for r in 0..n { + if r != row_idx && row_x[r].x_bits.get_bit(bit) { + let p_clone = pivot.clone(); + row_x[r] = row_x[r].multiply(&p_clone); + } + } + } else { + return (0.0, 0.0); + } + } + + if !target.is_identity() { + return (0.0, 0.0); + } + + // Build S_0 = product of selected generators + let mut s0 = Bm::default(); + let mut s0_phase: u8 = 0; // i^{s0_phase} + let mut s0_sign_minus = false; + + for i in 0..n { + if selected[i] { + let (prod, phase) = s0.multiply_with_phase(&stabilizers[i]); + s0 = prod; + s0_phase = (s0_phase + phase) % 4; + if stabilizer_phases[i] { + s0_sign_minus = !s0_sign_minus; + } + } + } + + // S_0 has sign (-1)^{s0_sign_minus} · i^{s0_phase} + // Compute PSQ = P · S_0 · Q + let (ps, phase_ps) = p.multiply_with_phase(&s0); + let (psq, phase_psq_part) = ps.multiply_with_phase(q); + let total_phase = (phase_ps + phase_psq_part + s0_phase) % 4; + + // PSQ should be diagonal (x_part = 0) + if !psq.x_bits.is_zero() { + return (0.0, 0.0); // Shouldn't happen if solution found correctly + } + + // Compute (-1)^{z_{PSQ} · x} + let mut dot = 0u32; + for (i, &bit) in outcome.iter().enumerate() { + if bit && psq.z_bits.get_bit(i) { + dot += 1; + } + } + let z_sign: f64 = if dot % 2 == 0 { 1.0 } else { -1.0 }; + + // Total sign from S_0 being a (-1)^{sign} stabilizer + let stab_sign: f64 = if s0_sign_minus { -1.0 } else { 1.0 }; + + // Φ = i^{total_phase} · stab_sign · z_sign + let (re, im) = match total_phase { + 0 => (1.0, 0.0), + 1 => (0.0, 1.0), + 2 => (-1.0, 0.0), + 3 => (0.0, -1.0), + _ => unreachable!(), + }; + + (re * stab_sign * z_sign, im * stab_sign * z_sign) +} + +/// Check if outcome x is in the support of the stabilizer state. +/// +/// x ∈ support iff for every stabilizer generator S, ⟨x|S|x⟩ = +1. +/// For S = phase · X^a Z^b: ⟨x|S|x⟩ = phase · δ_{a,0} · (-1)^{b·x} +/// (since X flips bits, ⟨x|X^a|x⟩ = 0 unless a=0). +/// +/// Wait: that's only for diagonal stabilizers. For non-diagonal (X or Y +/// components), ⟨x|S|x⟩ = 0 ≠ +1, so x is not in the support if any +/// stabilizer has X component. But stabilizer states CAN have X-type +/// stabilizers and still have x in the support. +/// +/// The correct check: x is in the support iff for all Z-type stabilizers +/// (those with no X component), the Z eigenvalue matches. +fn is_in_support(outcome: &[bool], stabilizers: &[Bm]) -> bool { + for stab in stabilizers { + // Only Z-type stabilizers constrain the support + if !stab.x_bits.is_zero() { + continue; // Has X component — doesn't constrain Z-basis support + } + + // Z-type stabilizer: eigenvalue = (-1)^{popcount(z_bits & x)} + let mut parity = 0u32; + for (i, &bit) in outcome.iter().enumerate() { + if bit && stab.z_bits.get_bit(i) { + parity += 1; + } + } + // Stabilizer eigenvalue should be +1 on support states + if parity % 2 != 0 { + return false; // eigenvalue = -1, not in support + } + } + true +} + +/// Flip outcome bits according to the X-component of a Pauli. +fn flip_outcome(outcome: &[bool], pauli: &Bm) -> Vec { + outcome + .iter() + .enumerate() + .map(|(i, &bit)| if pauli.has_x(i) { !bit } else { bit }) + .collect() +} + +/// Compute ζ = number of qubits whose Z-basis outcome is non-deterministic. +/// +/// ζ = n - (number of independent Z-type stabilizer generators). +fn compute_zeta(n: usize, stabilizers: &[Bm]) -> usize { + // Count independent Z-type stabilizers (no X component). + // Extract Z-parts as Bm (store z in x_bits for GF2 rank). + let z_stabs: Vec = stabilizers + .iter() + .filter(|s| s.x_bits.is_zero()) + .map(|s| Bm { x_bits: s.z_bits.clone(), z_bits: Default::default() }) + .collect(); + + let rank = gf2_rank_bitmask(&z_stabs, n); + n.saturating_sub(rank) +} + +/// GF(2) rank of binary vectors stored as Bm x_bits. +fn gf2_rank_bitmask(vectors: &[Bm], max_bits: usize) -> usize { + let mut rows: Vec = vectors.to_vec(); + let mut rank = 0; + + for bit in 0..max_bits { + if rank >= rows.len() { break; } + if rows[rank..].iter().all(|r| r.is_identity()) { break; } + if let Some(pivot) = rows[rank..].iter().position(|r| r.x_bits.get_bit(bit)) { + rows.swap(rank, rank + pivot); + let pivot_val = rows[rank].clone(); + for r in 0..rows.len() { + if r != rank && rows[r].x_bits.get_bit(bit) { + rows[r] = rows[r].multiply(&pivot_val); + } + } + rank += 1; + } + } + + rank +} + +#[cfg(test)] +mod tests { + use super::*; + + fn xx() -> Bm { Bm::x(0).multiply(&Bm::x(1)) } + fn zz() -> Bm { Bm::z(0).multiply(&Bm::z(1)) } + + #[test] + fn test_single_qubit_z_basis() { + // |0⟩ state: stabilizer = +Z. Outcome 0 is deterministic. + let stabs = vec![Bm::z(0)]; + let outcome_0 = vec![false]; // |0⟩ + let outcome_1 = vec![true]; // |1⟩ + + assert!(is_in_support(&outcome_0, &stabs)); + assert!(!is_in_support(&outcome_1, &stabs)); + + // With S_X noise: flips |0⟩ to |1⟩ + let gens = vec![PropagatedEeg { + eeg_type: EegType::S, + label: Bm::x(0), + label2: None, + coeff: -0.01, + source: None, + }]; + + let p0 = outcome_probability(&gens, &outcome_0, &stabs); + let p1 = outcome_probability(&gens, &outcome_1, &stabs); + + // p(0) ≈ 1 - 0.01 = 0.99 (S_X moves probability from 0 to 1) + // p(1) ≈ 0 + 0.01 = 0.01 + assert!((p0.noiseless - 1.0).abs() < 1e-10); + assert!((p0.s_correction - 0.01).abs() < 1e-10); + assert!((p0.h_correction).abs() < 1e-10); // no H generators + assert!((p0.total - 0.99).abs() < 0.02); + + assert!((p1.noiseless - 0.0).abs() < 1e-10); + assert!((p1.s_correction + 0.01).abs() < 1e-10); + } + + #[test] + fn test_h_type_diagonal_correction() { + // |+⟩ state: stabilizer = +X. Z-basis outcomes 0,1 each with prob 1/2. + // With H_Z noise (coherent Z rotation): shifts probability from 0 to 1. + let stabs = vec![Bm::x(0)]; // |+⟩ + let outcome_0 = vec![false]; + let outcome_1 = vec![true]; + + let gens = vec![PropagatedEeg { + eeg_type: EegType::H, + label: Bm::z(0), // H_Z: Z rotation + label2: None, + coeff: 0.1, + source: None, + }]; + + let p0 = outcome_probability(&gens, &outcome_0, &stabs); + let p1 = outcome_probability(&gens, &outcome_1, &stabs); + + // |+⟩ support: {0, 1} with ζ=1. Both outcomes in support. + assert!((p0.noiseless - 0.5).abs() < 1e-10); + assert!((p1.noiseless - 0.5).abs() < 1e-10); + + // H_Z diagonal α: Z flips no bits (a_Z = 0), so x⊕a = x. + // α(S_Z) = [x ∈ supp] - [x ∈ supp] = 0 for Z-type Paulis. + // So the H·H diagonal correction via S_P analogy should be 0 + // (Z has no X component, doesn't flip outcome bits). + assert!((p0.h_correction).abs() < 1e-10); + + // H_X noise would flip bits: + let gens_x = vec![PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), // H_X + label2: None, + coeff: 0.1, + source: None, + }]; + let p0x = outcome_probability(&gens_x, &outcome_0, &stabs); + // X flips bit: α = [1∈supp] - [0∈supp] = 1-1 = 0 (both in support) + // So h_correction = 0 for |+⟩ with H_X too (both outcomes in support) + assert!((p0x.h_correction).abs() < 1e-10); + } + + #[test] + fn test_h_type_shifts_probability() { + // |0⟩ state with H_X noise: X flips from |0⟩ to |1⟩ + let stabs = vec![Bm::z(0)]; // |0⟩ + let outcome_0 = vec![false]; + let outcome_1 = vec![true]; + + let gens = vec![PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), // H_X + label2: None, + coeff: 0.1, // small angle + source: None, + }]; + + let p0 = outcome_probability(&gens, &outcome_0, &stabs); + let p1 = outcome_probability(&gens, &outcome_1, &stabs); + + // |0⟩: only outcome 0 is in support. + // α(S_X) for outcome 0: [1∈supp] - [0∈supp] = 0-1 = -1 + // Diagonal H·H: h² · α = 0.01 · (-1) = -0.01 + assert!((p0.h_correction + 0.01).abs() < 1e-10); + assert!((p0.total - 0.99).abs() < 0.02); + + // α(S_X) for outcome 1: [0∈supp] - [1∈supp] = 1-0 = +1 + // h² · α = 0.01 · 1 = +0.01 + assert!((p1.h_correction - 0.01).abs() < 1e-10); + assert!((p1.total - 0.01).abs() < 0.02); + } + + #[test] + fn test_bell_state_support() { + // |Φ+⟩ = (|00⟩+|11⟩)/√2. Stabilizers: +XX, +ZZ + let stabs = vec![xx(), zz()]; + + // Support: {00, 11} (Z-type stabilizer ZZ constrains parity) + assert!(is_in_support(&[false, false], &stabs)); // 00: ZZ eigenvalue = (-1)^0 = +1 + assert!(is_in_support(&[true, true], &stabs)); // 11: ZZ eigenvalue = (-1)^2 = +1 + assert!(!is_in_support(&[false, true], &stabs)); // 01: ZZ eigenvalue = (-1)^1 = -1 + assert!(!is_in_support(&[true, false], &stabs)); // 10: ZZ eigenvalue = (-1)^1 = -1 + } + + #[test] + fn test_zeta_computation() { + // Single qubit |0⟩: 1 Z-type stabilizer, ζ = 1-1 = 0 (deterministic) + assert_eq!(compute_zeta(1, &[Bm::z(0)]), 0); + + // Bell state: 1 Z-type stabilizer (ZZ), ζ = 2-1 = 1 + let bell_stabs = vec![xx(), zz()]; + assert_eq!(compute_zeta(2, &bell_stabs), 1); + + // |+⟩: 0 Z-type stabilizers, ζ = 1-0 = 1 + assert_eq!(compute_zeta(1, &[Bm::x(0)]), 1); + } + + #[test] + fn test_phi_single_qubit() { + // |0⟩: stabilizer +Z + let stabs = vec![Bm::z(0)]; + let phases = vec![false]; // +1 stabilizer + + // Φ(I,I) for outcome 0 (in support): should be 1 + let phi = compute_phi( + &Bm::default(), &Bm::default(), + &[false], &stabs, &phases, + ); + assert!((phi.0 - 1.0).abs() < 1e-10); + assert!(phi.1.abs() < 1e-10); + + // Φ(I,I) for outcome 1 (not in support): should be 0 + let phi = compute_phi( + &Bm::default(), &Bm::default(), + &[true], &stabs, &phases, + ); + assert!(phi.0.abs() < 1e-10); + + // Φ(X,X) for outcome 0: ⟨0|X|0⟩² = 0 (X flips to |1⟩ which is not in support... + // wait, x⊕a_X = 1, is |1⟩ in support? No. So Φ = 0. + let phi = compute_phi( + &Bm::x(0), &Bm::x(0), + &[false], &stabs, &phases, + ); + assert!(phi.0.abs() < 1e-10); + + // Φ(X,X) for outcome 1: ⟨1|X|0⟩·⟨0|X|1⟩ = ⟨1|1⟩·⟨0|0⟩ = 1 + // x⊕a_X = 0, which IS in support. So Φ should be 1. + let phi = compute_phi( + &Bm::x(0), &Bm::x(0), + &[true], &stabs, &phases, + ); + assert!((phi.0 - 1.0).abs() < 1e-10, "Phi(X,X) at |1> for |0> state: got {:?}", phi); + + // Φ(Z,I) for outcome 0: ⟨0|Z|0⟩·⟨0|0⟩ = 1·1 = 1 + let phi = compute_phi( + &Bm::z(0), &Bm::default(), + &[false], &stabs, &phases, + ); + assert!((phi.0 - 1.0).abs() < 1e-10); + } + + #[test] + fn test_phi_bell_state() { + // |Φ+⟩ = (|00⟩+|11⟩)/√2. Stabilizers: +XX, +ZZ. ζ = 1. + let stabs = vec![xx(), zz()]; + let phases = vec![false, false]; + + // Φ(I,I) for outcome 00 (in support): 2^ζ · |⟨00|Φ+⟩|² = 2 · 1/2 = 1 + let phi = compute_phi( + &Bm::default(), &Bm::default(), + &[false, false], &stabs, &phases, + ); + assert!((phi.0 - 1.0).abs() < 1e-10, "Phi(I,I) at 00: {:?}", phi); + + // Φ(I,I) for outcome 01 (not in support): 0 + let phi = compute_phi( + &Bm::default(), &Bm::default(), + &[false, true], &stabs, &phases, + ); + assert!(phi.0.abs() < 1e-10); + + // Φ(Z0,I) for outcome 00 + let phi = compute_phi( + &Bm::z(0), &Bm::default(), + &[false, false], &stabs, &phases, + ); + assert!((phi.0 - 1.0).abs() < 1e-10, "Phi(Z0,I) at 00: {:?}", phi); + + // Φ(Z0,I) for outcome 11 + let phi = compute_phi( + &Bm::z(0), &Bm::default(), + &[true, true], &stabs, &phases, + ); + assert!((phi.0 + 1.0).abs() < 1e-10, "Phi(Z0,I) at 11: {:?}", phi); + } + + #[test] + fn test_bell_state_strong_sim() { + // |Φ+⟩ with S_{Z₀} noise (Z error on qubit 0) + let stabs = vec![xx(), zz()]; + + let gens = vec![PropagatedEeg { + eeg_type: EegType::S, + label: Bm::z(0), // S_Z on qubit 0 + label2: None, + coeff: -0.01, + source: None, + }]; + + // Noiseless: p(00) = p(11) = 1/2, p(01) = p(10) = 0 + let p00 = outcome_probability(&gens, &[false, false], &stabs); + let p11 = outcome_probability(&gens, &[true, true], &stabs); + let p01 = outcome_probability(&gens, &[false, true], &stabs); + let p10 = outcome_probability(&gens, &[true, false], &stabs); + + assert!((p00.noiseless - 0.5).abs() < 1e-10); + assert!((p11.noiseless - 0.5).abs() < 1e-10); + assert!(p01.noiseless.abs() < 1e-10); + assert!(p10.noiseless.abs() < 1e-10); + + // S_{Z₀} on |Φ+⟩: Z₀ maps |Φ+⟩ to |Φ-⟩. No Z-basis effect. + assert!(p00.s_correction.abs() < 1e-10, "Z error on Bell state: no Z-basis effect"); + assert!(p11.s_correction.abs() < 1e-10); + } +} diff --git a/exp/pecos-eeg/tests/beta_investigation.rs b/exp/pecos-eeg/tests/beta_investigation.rs new file mode 100644 index 000000000..7dabba98c --- /dev/null +++ b/exp/pecos-eeg/tests/beta_investigation.rs @@ -0,0 +1,154 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Investigation: why off-diagonal beta terms don't fire for Z-basis. + +use pecos_core::gate_type::GateType; +use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; +use pecos_eeg::Bm; +use pecos_eeg::circuit::{analyze_expanded, NoiseModel, PropagatedEeg}; +use pecos_eeg::eeg::EegType; +use pecos_eeg::expand; +use pecos_eeg::stabilizer::StabilizerGroup; + +fn gate(gt: GateType, qubits: &[usize]) -> Gate { + Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), + } +} + +/// Build a minimal Z-basis circuit: 2 data + 1 X-ancilla, 2 rounds. +fn build_minimal_zbasis() -> Vec { + vec![ + // Init + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), // X-ancilla + // Round 1 + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + gate(GateType::PZ, &[2]), + // Round 2 + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + // Final data readout + gate(GateType::MZ, &[0]), + gate(GateType::MZ, &[1]), + ] +} + +#[test] +fn test_zbasis_generator_labels() { + let gates = build_minimal_zbasis(); + let expanded = expand::expand_circuit(&gates); + + eprintln!("Expanded circuit: {} qubits ({} original + {} aux)", + expanded.num_qubits, expanded.num_original_qubits, + expanded.num_qubits - expanded.num_original_qubits); + eprintln!("Measurement mapping:"); + for (i, (&aux, &orig)) in expanded.measurement_qubit.iter() + .zip(expanded.original_measured_qubit.iter()).enumerate() + { + eprintln!(" meas {i}: aux={aux} orig={orig}"); + } + + let noise = NoiseModel::coherent_only(0.001); + let result = analyze_expanded(&expanded.gates, &noise); + + let h_gens: Vec<&PropagatedEeg> = result.generators.iter() + .filter(|g| g.eeg_type == EegType::H) + .collect(); + + eprintln!("\nH generators ({}):", h_gens.len()); + for (i, g) in h_gens.iter().enumerate() { + let orig = expanded.map_to_original_frame(&g.label); + eprintln!(" [{i}] expanded={:?} coeff={:.6} original_frame={:?}", + g.label, g.coeff, orig); + } + + // Check products of all pairs + eprintln!("\nPairwise products:"); + let stab_group = StabilizerGroup::from_circuit(&gates, expanded.num_original_qubits); + + for j in 0..h_gens.len() { + for k in (j+1)..h_gens.len() { + let qj = &h_gens[j].label; + let qk = &h_gens[k].label; + if !qj.commutes_with(qk) { + continue; // Skip anticommuting pairs + } + let product = qj.multiply(qk); + let orig_product = expanded.map_to_original_frame(&product); + let is_stab = stab_group.is_stabilizer(&orig_product); + + if is_stab.is_some() || !orig_product.is_identity() { + eprintln!(" [{j},{k}] commute=true product_orig={:?} is_stab={:?}", + orig_product, is_stab); + } + } + } +} + +#[test] +fn test_zbasis_stabilizer_group() { + let gates = build_minimal_zbasis(); + // Exclude final MZ readout — keep syndrome MZ + let last_non_mz = gates.iter().rposition(|g| g.gate_type != GateType::MZ).unwrap(); + let gates_pre = &gates[..=last_non_mz]; + let stab_group = StabilizerGroup::from_circuit(gates_pre, 3); + + // Dump actual generators + eprintln!("Stabilizer generators:"); + // Run SparseStab manually to see generators + use pecos_simulators::{CliffordGateable, SparseStab}; + let mut sim = SparseStab::with_seed(3, 0); + for g in gates_pre { + let qs: Vec = g.qubits.iter().copied().collect(); + match g.gate_type { + GateType::PZ => { for &q in &qs { sim.pz(&[q]); } } + GateType::H => { sim.h(&qs); } + GateType::CX => { if qs.len() >= 2 { sim.cx(&[(qs[0], qs[1])]); } } + GateType::MZ => { let _r = sim.mz(&qs); eprintln!(" MZ({:?})", qs); } + _ => {} + } + } + let stab_gens = sim.stabs().generators(); + for (i, g) in stab_gens.iter().enumerate() { + eprintln!(" stab[{i}] = {g:?}"); + } + + // Check what's in the stabilizer group + eprintln!("\nStabilizer group membership checks:"); + let test_paulis = vec![ + ("X0", Bm::x(0)), + ("X1", Bm::x(1)), + ("X0X1", Bm::x(0).multiply(&Bm::x(1))), + ("Z0", Bm::z(0)), + ("Z1", Bm::z(1)), + ("Z0Z1", Bm::z(0).multiply(&Bm::z(1))), + ("Z2", Bm::z(2)), + ]; + + for (name, p) in &test_paulis { + let result = stab_group.is_stabilizer(p); + eprintln!(" {name}: {result:?}"); + } + + // X0*X1 should be a stabilizer (from X-type syndrome extraction) + assert_eq!( + stab_group.is_stabilizer(&Bm::x(0).multiply(&Bm::x(1))), + Some(true), + "X0*X1 should be stabilizer after 2 rounds of X-stabilizer measurement" + ); +} diff --git a/exp/pecos-eeg/tests/generator_trace.rs b/exp/pecos-eeg/tests/generator_trace.rs new file mode 100644 index 000000000..25a016aa4 --- /dev/null +++ b/exp/pecos-eeg/tests/generator_trace.rs @@ -0,0 +1,320 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Trace generator propagation for d=2 Z-basis surface code. +//! Diagnose why D1 and D2 have identical EEG probabilities +//! when StateVec shows they should differ. + +use pecos_core::gate_type::GateType; +use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; +use pecos_eeg::Bm; +use pecos_eeg::circuit::{analyze_expanded, NoiseModel}; +use pecos_eeg::dem_mapping::*; +use pecos_eeg::eeg::EegType; +use pecos_eeg::expand; +use pecos_eeg::stabilizer::StabilizerGroup; + +fn gate(gt: GateType, qubits: &[usize]) -> Gate { + Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), + } +} + +/// Build the d=2 Z-basis surface code circuit (2 rounds). +/// Matches what LogicalCircuitBuilder produces. +fn build_d2_zbasis() -> Vec { + vec![ + // Init + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), gate(GateType::PZ, &[3]), + gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[6]), + // Round 1 + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), // tick 3 + gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), // tick 4 + gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), // tick 5 + gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), // tick 6 + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::MZ, &[6]), + // Reset + gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[6]), + // Round 2 + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), // tick 11 + gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), // tick 12 + gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), // tick 13 + gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), // tick 14 + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::MZ, &[6]), + // Final data readout + gate(GateType::MZ, &[0]), gate(GateType::MZ, &[1]), + gate(GateType::MZ, &[2]), gate(GateType::MZ, &[3]), + ] +} + +#[test] +fn trace_d2_zbasis_generators() { + let gates = build_d2_zbasis(); + let expanded = expand::expand_circuit(&gates); + let noise = NoiseModel::coherent_only(0.01); + let result = analyze_expanded(&expanded.gates, &noise); + + eprintln!("Expanded: {} qubits ({} orig + {} aux), {} measurements", + expanded.num_qubits, expanded.num_original_qubits, + expanded.num_qubits - expanded.num_original_qubits, + expanded.measurement_qubit.len()); + + eprintln!("\nMeasurement mapping:"); + for (i, (&aux, &orig)) in expanded.measurement_qubit.iter() + .zip(expanded.original_measured_qubit.iter()).enumerate() + { + eprintln!(" meas[{i}]: aux=q{aux}, orig=q{orig}"); + } + + // Detectors: D1 = Z_{aux_meas0} * Z_{aux_meas3} (ancilla 4, rounds 1&2) + // D2 = Z_{aux_meas1} * Z_{aux_meas4} (ancilla 5, rounds 1&2) + let aux_m0 = expanded.measurement_qubit[0]; // q4 round 1 + let aux_m1 = expanded.measurement_qubit[1]; // q5 round 1 + let aux_m3 = expanded.measurement_qubit[3]; // q4 round 2 + let aux_m4 = expanded.measurement_qubit[4]; // q5 round 2 + + let d1_stab = Bm::z(aux_m0).multiply(&Bm::z(aux_m3)); + let d2_stab = Bm::z(aux_m1).multiply(&Bm::z(aux_m4)); + + eprintln!("\nD1 stabilizer: Z on aux q{aux_m0} and q{aux_m3} (ancilla 4 rounds 1&2)"); + eprintln!("D2 stabilizer: Z on aux q{aux_m1} and q{aux_m4} (ancilla 5 rounds 1&2)"); + + let _dets = vec![ + Detector { id: 1, stabilizer: d1_stab.clone() }, + Detector { id: 2, stabilizer: d2_stab.clone() }, + ]; + + // Classify each H generator + let h_gens: Vec<_> = result.generators.iter() + .filter(|g| g.eeg_type == EegType::H) + .collect(); + + eprintln!("\n{} H generators. Classification:", h_gens.len()); + + let mut d1_gens = Vec::new(); + let mut d2_gens = Vec::new(); + + for g in &h_gens { + let flips_d1 = !g.label.commutes_with(&d1_stab); + let flips_d2 = !g.label.commutes_with(&d2_stab); + + if flips_d1 || flips_d2 { + let orig = expanded.map_to_original_frame(&g.label); + eprintln!(" {:?} coeff={:.6} -> orig={:?} flips: D1={} D2={}", + g.label, g.coeff, orig, flips_d1, flips_d2); + + if flips_d1 { d1_gens.push((g.label.clone(), g.coeff)); } + if flips_d2 { d2_gens.push((g.label.clone(), g.coeff)); } + } + } + + eprintln!("\nD1 generators: {} (ancilla 4)", d1_gens.len()); + for (label, coeff) in &d1_gens { + eprintln!(" {:?} coeff={:.6}", label, coeff); + } + + eprintln!("\nD2 generators: {} (ancilla 5)", d2_gens.len()); + for (label, coeff) in &d2_gens { + eprintln!(" {:?} coeff={:.6}", label, coeff); + } + + // After BCH combination (same label → sum coefficients) + use std::collections::BTreeMap; + let mut d1_bch: BTreeMap = BTreeMap::new(); + let mut d2_bch: BTreeMap = BTreeMap::new(); + for (l, c) in &d1_gens { *d1_bch.entry(l.clone()).or_default() += c; } + for (l, c) in &d2_gens { *d2_bch.entry(l.clone()).or_default() += c; } + + eprintln!("\nD1 after BCH: {} distinct labels", d1_bch.len()); + for (l, c) in &d1_bch { eprintln!(" {:?} rate={:.6}", l, c); } + + eprintln!("\nD2 after BCH: {} distinct labels", d2_bch.len()); + for (l, c) in &d2_bch { eprintln!(" {:?} rate={:.6}", l, c); } + + // Verify asymmetry in generator counts + assert_ne!(d1_bch.len(), d2_bch.len(), + "D1 and D2 should have different numbers of BCH-combined generators"); + + // Compute probabilities manually to trace the beta function + let gates_pre = crate::exclude_final_readout(&gates); + let stab_group = StabilizerGroup::from_circuit(&gates_pre, expanded.num_original_qubits); + + // Check what the stabilizer group contains + eprintln!("\nStabilizer group membership checks:"); + let test_paulis = vec![ + ("Z0", Bm::z(0)), + ("Z1", Bm::z(1)), + ("Z2", Bm::z(2)), + ("Z3", Bm::z(3)), + ("Z0Z1", Bm::z(0).multiply(&Bm::z(1))), + ("Z0Z3", Bm::z(0).multiply(&Bm::z(3))), + ("X0X1", Bm::x(0).multiply(&Bm::x(1))), + ]; + for (name, p) in &test_paulis { + let result = stab_group.is_stabilizer(p); + eprintln!(" {name}: {result:?}"); + } + + eprintln!("\nPre-readout gates count: {}", gates_pre.len()); + eprintln!("Original gates count: {}", gates.len()); + + // Dump raw SparseStab generators + { + use pecos_simulators::{CliffordGateable, SparseStab}; + let mut sim = SparseStab::with_seed(7, 0); + for g in &gates_pre { + let qs: Vec = g.qubits.iter().copied().collect(); + if qs.is_empty() { continue; } + match g.gate_type { + GateType::PZ => { for &q in &qs { sim.pz(&[q]); } } + GateType::H => { sim.h(&qs); } + GateType::CX => { if qs.len() >= 2 { sim.cx(&[(qs[0], qs[1])]); } } + GateType::MZ => { let _ = sim.mz(&qs); } + _ => {} + } + } + let stabs = sim.stabs(); + let n_gens = stabs.num_generators(); + eprintln!("\nSparseStab generators ({n_gens}):"); + for i in 0..n_gens { + let ps = stabs.generator(i); + let phase = stabs.generator_phase(i); + eprintln!(" [{i}] phase={phase:?} {ps}"); + } + + // Direct test: can find_pauli_sign find Z0? + let result = stabs.find_pauli_sign( + sim.destabs(), + std::iter::empty::(), + std::iter::once(0usize), + 0, + ); + eprintln!("\nfind_pauli_sign(Z0) WITH MZ = {:?}", result); + + // Try without MZ: skip measurements in stabilizer computation + let mut sim2 = SparseStab::with_seed(7, 0); + for g in &gates_pre { + let qs: Vec = g.qubits.iter().copied().collect(); + if qs.is_empty() { continue; } + match g.gate_type { + GateType::PZ => { for &q in &qs { sim2.pz(&[q]); } } + GateType::H => { sim2.h(&qs); } + GateType::CX => { if qs.len() >= 2 { sim2.cx(&[(qs[0], qs[1])]); } } + GateType::MZ => { /* skip */ } + _ => {} + } + } + let stabs2 = sim2.stabs(); + let result2 = stabs2.find_pauli_sign( + sim2.destabs(), + std::iter::empty::(), + std::iter::once(0usize), + 0, + ); + eprintln!("find_pauli_sign(Z0) WITHOUT MZ = {:?}", result2); + + // Check X0X1 without MZ + let result3 = stabs2.find_pauli_sign( + sim2.destabs(), + [0usize, 1].into_iter(), + std::iter::empty::(), + 0, + ); + eprintln!("find_pauli_sign(X0X1) WITHOUT MZ = {:?}", result3); + } + + // Check: how many qubits in the stabilizer group? And test Z0Z1Z2Z3 + let z_all = Bm::z(0).multiply(&Bm::z(1)).multiply(&Bm::z(2)).multiply(&Bm::z(3)); + eprintln!("Z0Z1Z2Z3: {:?}", stab_group.is_stabilizer(&z_all)); + let _z01 = Bm::z(0).multiply(&Bm::z(1)); + let z23 = Bm::z(2).multiply(&Bm::z(3)); + eprintln!("Z2Z3: {:?}", stab_group.is_stabilizer(&z23)); + eprintln!("Z0Z1Z2: {:?}", stab_group.is_stabilizer(&Bm::z(0).multiply(&Bm::z(1)).multiply(&Bm::z(2)))); + eprintln!("Z1Z2: {:?}", stab_group.is_stabilizer(&Bm::z(1).multiply(&Bm::z(2)))); + + for (det_name, bch) in [("D1", &d1_bch), ("D2", &d2_bch)] { + let labels: Vec = bch.keys().cloned().collect(); + let coeffs: Vec = bch.values().copied().collect(); + let n = labels.len(); + + let mut diag = 0.0; + let mut offdiag = 0.0; + let mut offdiag_zero = 0; + let mut offdiag_plus = 0; + let mut offdiag_minus = 0; + let mut offdiag_anticommute = 0; + + for j in 0..n { + diag += coeffs[j] * coeffs[j]; + for k in (j+1)..n { + if !labels[j].commutes_with(&labels[k]) { + offdiag_anticommute += 1; + continue; + } + let product = labels[j].multiply(&labels[k]); + let orig_product = expanded.map_to_original_frame(&product); + + if orig_product.is_identity() { + offdiag += 2.0 * coeffs[j] * coeffs[k]; + offdiag_plus += 1; + continue; + } + match stab_group.is_stabilizer(&orig_product) { + Some(true) => { + offdiag += 2.0 * coeffs[j] * coeffs[k]; + offdiag_plus += 1; + } + Some(false) => { + offdiag -= 2.0 * coeffs[j] * coeffs[k]; + offdiag_minus += 1; + } + None => { + offdiag_zero += 1; + eprintln!(" beta=0: {:?} * {:?} = {:?} (orig: {:?})", + labels[j], labels[k], product, orig_product); + } + } + } + } + + let total = diag + offdiag; + eprintln!("\n{det_name} probability breakdown:"); + eprintln!(" Diagonal: {diag:.8}"); + eprintln!(" Off-diagonal: {offdiag:.8} (+{offdiag_plus} pairs, -{offdiag_minus} pairs, 0:{offdiag_zero} pairs, anticommute:{offdiag_anticommute})"); + eprintln!(" Total: {total:.8}"); + } +} + +fn exclude_final_readout(gates: &[Gate]) -> Vec { + use pecos_core::gate_type::GateType; + let mut ancilla_qubits = std::collections::HashSet::new(); + let mut past_init = false; + for g in gates { + if past_init && (g.gate_type == GateType::PZ || g.gate_type == GateType::QAlloc) { + for q in &g.qubits { ancilla_qubits.insert(q.index()); } + } + if g.gate_type != GateType::PZ && g.gate_type != GateType::QAlloc { past_init = true; } + } + let mut end = gates.len(); + for g in gates.iter().rev() { + if g.gate_type != GateType::MZ { break; } + if g.qubits.iter().all(|q| !ancilla_qubits.contains(&q.index())) { + end -= 1; + } else { break; } + } + gates[..end].to_vec() +} diff --git a/exp/pecos-eeg/tests/stabilizer_audit.rs b/exp/pecos-eeg/tests/stabilizer_audit.rs new file mode 100644 index 000000000..061eb1cf5 --- /dev/null +++ b/exp/pecos-eeg/tests/stabilizer_audit.rs @@ -0,0 +1,174 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Audit: does the StabilizerGroup correctly identify all stabilizers? +//! Test by generating all 2^n products of n generators and checking +//! that is_stabilizer returns Some for each. + +use pecos_core::gate_type::GateType; +use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; +use pecos_eeg::Bm; +use pecos_eeg::stabilizer::StabilizerGroup; +use pecos_simulators::{CliffordGateable, SparseStab}; + +fn gate(gt: GateType, qubits: &[usize]) -> Gate { + Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), + } +} + +/// Extract generators as Bm from SparseStab. +fn extract_generators(sim: &SparseStab) -> Vec { + let stabs = sim.stabs(); + let n = stabs.num_generators(); + let mut gens = Vec::with_capacity(n); + for i in 0..n { + let ps = stabs.generator(i); + gens.push(pecos_eeg::dem_mapping::pauli_string_to_bitmask(&ps)); + } + gens +} + +/// Check that StabilizerGroup.is_stabilizer returns Some for ALL products +/// of the SparseStab generators (which are by definition in the group). +fn audit_stabilizer_group(label: &str, gates: &[Gate], num_qubits: usize) { + let stab_group = StabilizerGroup::from_circuit(gates, num_qubits); + + // Also build a raw SparseStab to extract generators + let mut sim = SparseStab::with_seed(num_qubits, 0); + for g in gates { + let qs: Vec = g.qubits.iter().copied().collect(); + if qs.is_empty() { continue; } + match g.gate_type { + GateType::PZ | GateType::QAlloc => { for &q in &qs { sim.pz(&[q]); } } + GateType::H => { sim.h(&qs); } + GateType::SZ => { sim.sz(&qs); } + GateType::SZdg => { sim.szdg(&qs); } + GateType::X => { sim.x(&qs); } + GateType::Y => { sim.y(&qs); } + GateType::Z => { sim.z(&qs); } + GateType::CX => { if qs.len() >= 2 { sim.cx(&[(qs[0], qs[1])]); } } + GateType::CZ => { if qs.len() >= 2 { sim.cz(&[(qs[0], qs[1])]); } } + GateType::MZ => { sim.mz(&qs); } + _ => {} + } + } + + let generators = extract_generators(&sim); + let n = generators.len(); + + eprintln!("\n{label}: {n} generators on {num_qubits} qubits"); + for (i, g) in generators.iter().enumerate() { + eprintln!(" gen[{i}] = {g:?}"); + } + + // Test all 2^n products (for small n) + let max_subsets = if n <= 10 { 1 << n } else { 1024 }; // cap at 1024 for large n + let mut failures = Vec::new(); + + for mask in 0..max_subsets { + let mut product = Bm::default(); + for i in 0..n { + if mask & (1 << i) != 0 { + product = product.multiply(&generators[i]); + } + } + + let result = stab_group.is_stabilizer(&product); + if result.is_none() && !product.is_identity() { + failures.push((mask, product)); + } + } + + if failures.is_empty() { + eprintln!(" OK: all {max_subsets} products correctly identified"); + } else { + eprintln!(" FAILURES: {} products not found:", failures.len()); + for (mask, product) in &failures { + let gens_used: Vec = (0..n).filter(|&i| mask & (1 << i) != 0).collect(); + eprintln!(" mask={mask:#06b} gens={gens_used:?} product={product:?}"); + } + } + + assert!(failures.is_empty(), + "{label}: {}/{max_subsets} stabilizer products not found by is_stabilizer", + failures.len()); +} + +#[test] +fn audit_simple_states() { + // |0>: stabilizer = Z + audit_stabilizer_group("|0>", &[], 1); + + // |+>: stabilizer = X + audit_stabilizer_group("|+>", &[gate(GateType::H, &[0])], 1); + + // Bell state + audit_stabilizer_group("|Phi+>", &[ + gate(GateType::H, &[0]), + gate(GateType::CX, &[0, 1]), + ], 2); +} + +#[test] +fn audit_syndrome_extraction() { + // Simple 2-qubit Z-check with ancilla: PZ(0,1,2), CX(0,2), CX(1,2), MZ(2) + audit_stabilizer_group("Z-check 2q", &[ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::CX, &[0, 2]), + gate(GateType::CX, &[1, 2]), + gate(GateType::MZ, &[2]), + ], 3); + + // X-check: H(2), CX(2,0), CX(2,1), H(2), MZ(2) + audit_stabilizer_group("X-check 2q", &[ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + ], 3); +} + +#[test] +fn audit_d2_zbasis_pre_readout() { + // d=2 Z-basis surface code, 2 rounds, pre-readout circuit + let gates = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), gate(GateType::PZ, &[3]), + gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[6]), + // Round 1 + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), + gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), + gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), + gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::MZ, &[6]), + // Reset + gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[6]), + // Round 2 + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), + gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), + gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), + gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), + gate(GateType::H, &[4]), gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::MZ, &[6]), + ]; + audit_stabilizer_group("d=2 Z-basis pre-readout", &gates, 7); +} diff --git a/exp/pecos-eeg/tests/statevec_comparison.rs b/exp/pecos-eeg/tests/statevec_comparison.rs new file mode 100644 index 000000000..f1709623e --- /dev/null +++ b/exp/pecos-eeg/tests/statevec_comparison.rs @@ -0,0 +1,1704 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Ground-truth comparison: EEG analytical DEM vs StateVec simulation. +//! +//! Uses Bell-state parity circuit where idle RZ noise creates detectable +//! parity violations. Without noise, MZ parity is always even. +//! With RZ(θ) noise after CX, P(odd parity) = sin²(θ). +//! EEG predicts ≈ θ² at leading order. + +use pecos_core::gate_type::GateType; +use pecos_core::pauli::pauli_bitmask::BitmaskStorage; +use pecos_core::{Angle64, Gate, GateAngles, GateParams, GateQubits, QubitId}; +use pecos_eeg::Bm; +use pecos_eeg::circuit::{analyze_expanded, NoiseModel}; +use pecos_eeg::dem_mapping::{build_dem_with_stabilizers, Detector}; +use pecos_eeg::expand; +use pecos_eeg::noise::UniformNoise; +use pecos_eeg::stabilizer::StabilizerGroup; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, StateVec}; + +fn gate(gt: GateType, qubits: &[usize]) -> Gate { + Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), + } +} + +fn qid(q: usize) -> QubitId { + QubitId(q) +} + +// ============================================================ +// Shared helpers for EEG analysis and StateVec simulation +// ============================================================ + +/// Run EEG on a gate list with a parity detector over all measurements. +fn eeg_detection_prob(gates: &[Gate], theta: f64) -> f64 { + let expanded = expand::expand_circuit(gates); + let noise = NoiseModel::coherent_only(theta); + let result = analyze_expanded(&expanded.gates, &noise); + + // Parity detector: Z on all auxiliary qubits + let mut det_stab = Bm::default(); + for &aux in &expanded.measurement_qubit { + det_stab.z_bits.set_bit(aux); + } + let det = Detector { id: 0, stabilizer: det_stab }; + + // Stabilizer group from expanded circuit (strip trailing deferred MZ) + let exp_pre: Vec<_> = { + let last = expanded.gates.iter().rposition(|g| g.gate_type != GateType::MZ).unwrap(); + expanded.gates[..=last].to_vec() + }; + let stab_group = StabilizerGroup::from_circuit(&exp_pre, expanded.num_qubits); + + let entries = build_dem_with_stabilizers( + &result.generators, &[det], &[], Some(&stab_group), + ); + + entries.iter().map(|e| e.probability).sum() +} + +/// Run EEG with per-round detectors, return per-detector probabilities. +fn eeg_per_round_probs(gates: &[Gate], theta: f64, num_rounds: usize) -> Vec { + let expanded = expand::expand_circuit(gates); + let noise = NoiseModel::coherent_only(theta); + let result = analyze_expanded(&expanded.gates, &noise); + + // One detector per round (Z on that round's aux qubit) + let dets: Vec = (0..num_rounds).map(|r| { + let aux = expanded.measurement_qubit[r]; + Detector { id: r, stabilizer: Bm::z(aux) } + }).collect(); + + // Stabilizer group from expanded circuit (strip trailing deferred MZ) + let exp_pre: Vec<_> = { + let last = expanded.gates.iter().rposition(|g| g.gate_type != GateType::MZ).unwrap(); + expanded.gates[..=last].to_vec() + }; + let stab_group = StabilizerGroup::from_circuit(&exp_pre, expanded.num_qubits); + + let entries = build_dem_with_stabilizers( + &result.generators, &dets, &[], Some(&stab_group), + ); + + let mut probs = vec![0.0; num_rounds]; + for e in &entries { + for &d in &e.event.detectors { + probs[d] += e.probability; + } + } + probs +} + +/// Bell-state parity circuit: +/// PZ(0,1), H(0), CX(0,1), [idle RZ], H(0), H(1), MZ(0), MZ(1) +/// +/// Without noise: |Φ+> → H⊗H → |Φ+> → MZ parity always even. +/// With RZ(θ) on both qubits: P(odd parity) = sin²(θ) ≈ θ² at leading order. +#[test] +fn test_eeg_vs_statevec_bell_parity() { + let theta = 0.05; + let num_shots = 100_000; + + // --- EEG analytical path --- + let gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::H, &[0]), + gate(GateType::CX, &[0, 1]), + // idle RZ(θ) on both qubits is implicit in noise model + gate(GateType::H, &[0]), + gate(GateType::H, &[1]), + gate(GateType::MZ, &[0]), + gate(GateType::MZ, &[1]), + ]; + + let expanded = expand::expand_circuit(&gates); + let noise = NoiseModel::coherent_only(theta); + let result = analyze_expanded(&expanded.gates, &noise); + + // Parity detector: Z_aux0 * Z_aux1 + assert_eq!(expanded.measurement_qubit.len(), 2); + let aux0 = expanded.measurement_qubit[0]; + let aux1 = expanded.measurement_qubit[1]; + let mut det_stab = Bm::default(); + det_stab.z_bits.set_bit(aux0); + det_stab.z_bits.set_bit(aux1); + let det = Detector { id: 0, stabilizer: det_stab }; + + // Pre-readout stabilizer group (exclude final MZ gates) + // Stabilizer group from expanded circuit (strip trailing deferred MZ) + let exp_pre: Vec<_> = { + let last = expanded.gates.iter().rposition(|g| g.gate_type != GateType::MZ).unwrap(); + expanded.gates[..=last].to_vec() + }; + let stab_group = StabilizerGroup::from_circuit(&exp_pre, expanded.num_qubits); + + let entries = build_dem_with_stabilizers( + &result.generators, &[det], &[], Some(&stab_group), + ); + + let eeg_prob: f64 = entries.iter().map(|e| e.probability).sum(); + + // --- StateVec simulation path --- + let mut odd_parity_count = 0u64; + let mut sim = StateVec::new(2); + + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1)]); + sim.h(&[qid(0)]); + sim.cx(&[(qid(0), qid(1))]); + + // Idle RZ noise (same as EEG coherent_only model) + sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.rz(Angle64::from_radians(theta), &[qid(1)]); + + sim.h(&[qid(0)]); + sim.h(&[qid(1)]); + + let r = sim.mz(&[qid(0), qid(1)]); + if r[0].outcome != r[1].outcome { + odd_parity_count += 1; + } + } + + let sv_rate = odd_parity_count as f64 / num_shots as f64; + let sv_stderr = (sv_rate * (1.0 - sv_rate) / num_shots as f64).sqrt(); + let exact = (theta as f64).sin().powi(2); + + eprintln!("theta = {theta}"); + eprintln!("EEG: {eeg_prob:.6}"); + eprintln!("StateVec: {sv_rate:.6} +/- {sv_stderr:.6}"); + eprintln!("Exact: {exact:.6}"); + + // EEG should match StateVec within statistical noise + perturbative error. + // At θ=0.05: exact=sin²(0.05)≈0.002499, EEG leading-order≈θ²≈0.0025 + // Perturbative error is O(θ⁴) ≈ 6.25e-6, well within statistical noise. + let diff = (eeg_prob - sv_rate).abs(); + let tolerance = 5.0 * sv_stderr + theta.powi(4); // 5σ + perturbative bound + assert!(diff < tolerance, + "EEG ({eeg_prob:.6}) vs StateVec ({sv_rate:.6}): diff={diff:.6} > tol={tolerance:.6}"); +} + +/// Same comparison at larger angle to verify scaling. +#[test] +fn test_eeg_vs_statevec_larger_angle() { + let theta = 0.1; + let num_shots = 100_000; + + let gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::H, &[0]), + gate(GateType::CX, &[0, 1]), + gate(GateType::H, &[0]), + gate(GateType::H, &[1]), + gate(GateType::MZ, &[0]), + gate(GateType::MZ, &[1]), + ]; + + let expanded = expand::expand_circuit(&gates); + let noise = NoiseModel::coherent_only(theta); + let result = analyze_expanded(&expanded.gates, &noise); + + let aux0 = expanded.measurement_qubit[0]; + let aux1 = expanded.measurement_qubit[1]; + let mut det_stab = Bm::default(); + det_stab.z_bits.set_bit(aux0); + det_stab.z_bits.set_bit(aux1); + let det = Detector { id: 0, stabilizer: det_stab }; + + // Stabilizer group from expanded circuit (strip trailing deferred MZ) + let exp_pre: Vec<_> = { + let last = expanded.gates.iter().rposition(|g| g.gate_type != GateType::MZ).unwrap(); + expanded.gates[..=last].to_vec() + }; + let stab_group = StabilizerGroup::from_circuit(&exp_pre, expanded.num_qubits); + + let entries = build_dem_with_stabilizers( + &result.generators, &[det], &[], Some(&stab_group), + ); + + let eeg_prob: f64 = entries.iter().map(|e| e.probability).sum(); + + let mut odd_parity_count = 0u64; + let mut sim = StateVec::new(2); + + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1)]); + sim.h(&[qid(0)]); + sim.cx(&[(qid(0), qid(1))]); + sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.rz(Angle64::from_radians(theta), &[qid(1)]); + sim.h(&[qid(0)]); + sim.h(&[qid(1)]); + let r = sim.mz(&[qid(0), qid(1)]); + if r[0].outcome != r[1].outcome { + odd_parity_count += 1; + } + } + + let sv_rate = odd_parity_count as f64 / num_shots as f64; + let sv_stderr = (sv_rate * (1.0 - sv_rate) / num_shots as f64).sqrt(); + let exact = (theta as f64).sin().powi(2); + + eprintln!("theta = {theta}"); + eprintln!("EEG: {eeg_prob:.6}"); + eprintln!("StateVec: {sv_rate:.6} +/- {sv_stderr:.6}"); + eprintln!("Exact: {exact:.6}"); + + // At θ=0.1: exact≈0.00998, EEG≈θ²≈0.01, perturbative error≈O(θ⁴)≈0.0001 + // Allow larger tolerance for bigger angle + let diff = (eeg_prob - sv_rate).abs(); + let tolerance = 5.0 * sv_stderr + 2.0 * theta.powi(4); + assert!(diff < tolerance, + "EEG ({eeg_prob:.6}) vs StateVec ({sv_rate:.6}): diff={diff:.6} > tol={tolerance:.6}"); +} + +// ============================================================ +// Benchmark sweeps (run with: cargo test -p pecos-eeg --test statevec_comparison -- --ignored --nocapture) +// ============================================================ + +/// Sweep theta for the Bell parity circuit. +/// Exact answer: sin²(θ). EEG leading-order: θ². +#[test] +#[ignore] +fn bench_bell_parity_theta_sweep() { + let num_shots = 200_000; + + let gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::H, &[0]), + gate(GateType::CX, &[0, 1]), + gate(GateType::H, &[0]), + gate(GateType::H, &[1]), + gate(GateType::MZ, &[0]), + gate(GateType::MZ, &[1]), + ]; + + eprintln!("\n=== Bell parity: EEG vs StateVec vs Exact ==="); + eprintln!("{:>8} {:>10} {:>10} {:>10} {:>10} {:>10}", + "theta", "EEG", "StateVec", "SV_stderr", "Exact", "EEG/Exact"); + + for &theta in &[0.01, 0.02, 0.05, 0.1, 0.15, 0.2, 0.3, 0.5] { + let eeg_prob = eeg_detection_prob(&gates, theta); + + let mut odd = 0u64; + let mut sim = StateVec::new(2); + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1)]); + sim.h(&[qid(0)]); + sim.cx(&[(qid(0), qid(1))]); + sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.rz(Angle64::from_radians(theta), &[qid(1)]); + sim.h(&[qid(0)]); + sim.h(&[qid(1)]); + let r = sim.mz(&[qid(0), qid(1)]); + if r[0].outcome != r[1].outcome { odd += 1; } + } + + let sv = odd as f64 / num_shots as f64; + let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + let exact = theta.sin().powi(2); + let ratio = if exact > 1e-10 { eeg_prob / exact } else { f64::NAN }; + + eprintln!("{theta:>8.3} {eeg_prob:>10.6} {sv:>10.6} {se:>10.6} {exact:>10.6} {ratio:>10.4}"); + } +} + +/// Multi-round X-check: 2 data qubits, 1 ancilla, N rounds of X-check with reset. +/// Data prepared in |++>, ancilla measures X0*X1 each round. +#[test] +#[ignore] +fn bench_x_check_multi_round() { + let num_shots = 200_000; + + eprintln!("\n=== Multi-round X-check (2 data + 1 ancilla) ==="); + + for &num_rounds in &[1, 2, 3, 4] { + // Build circuit: PZ(0,1,2), H(0), H(1), then N rounds of X-check + let mut gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::H, &[0]), + gate(GateType::H, &[1]), + ]; + + for _ in 0..num_rounds { + gates.push(gate(GateType::H, &[2])); + gates.push(gate(GateType::CX, &[2, 0])); + gates.push(gate(GateType::CX, &[2, 1])); + gates.push(gate(GateType::H, &[2])); + gates.push(gate(GateType::MZ, &[2])); + gates.push(gate(GateType::PZ, &[2])); + } + // Remove trailing PZ (no reset after last round) + gates.pop(); + + for &theta in &[0.01, 0.05, 0.1] { + let eeg_probs = eeg_per_round_probs(&gates, theta, num_rounds); + + // StateVec: run circuit with idle RZ after each CX + let mut round_detections = vec![0u64; num_rounds]; + let mut sim = StateVec::new(3); + + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1), qid(2)]); + sim.h(&[qid(0)]); + sim.h(&[qid(1)]); + + for round in 0..num_rounds { + sim.h(&[qid(2)]); + sim.cx(&[(qid(2), qid(0))]); + sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.cx(&[(qid(2), qid(1))]); + sim.rz(Angle64::from_radians(theta), &[qid(1)]); + sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.h(&[qid(2)]); + let r = sim.mz(&[qid(2)]); + if r[0].outcome { + round_detections[round] += 1; + } + if round < num_rounds - 1 { + sim.pz(&[qid(2)]); + } + } + } + + let sv_rates: Vec = round_detections.iter() + .map(|&d| d as f64 / num_shots as f64).collect(); + + eprintln!("\nrounds={num_rounds}, theta={theta}:"); + for r in 0..num_rounds { + let se = (sv_rates[r] * (1.0 - sv_rates[r]) / num_shots as f64).sqrt(); + let ratio = if sv_rates[r] > 1e-10 { eeg_probs[r] / sv_rates[r] } else { f64::NAN }; + eprintln!(" D{r}: EEG={:.6} SV={:.6}+/-{:.6} ratio={:.4}", + eeg_probs[r], sv_rates[r], se, ratio); + } + } + } +} + +/// Z-basis: data in |00>, Z-check measures Z0*Z1. Coherent RZ noise. +/// Z errors commute with Z measurements, so the X-propagated components matter. +#[test] +#[ignore] +fn bench_z_basis_check() { + let num_shots = 200_000; + + eprintln!("\n=== Z-basis parity check (CX syndrome extraction) ==="); + eprintln!("{:>8} {:>10} {:>10} {:>10} {:>10}", + "theta", "EEG", "StateVec", "SV_stderr", "EEG/SV"); + + // Z-check: CX(0,2), CX(1,2), MZ(2). Ancilla 2 measures Z0*Z1 parity. + // For |00>: Z0Z1|00> = +|00>, deterministic 0. + // RZ noise creates Z errors which don't flip Z-checks directly, + // but the CX propagation can create cross-terms. + let gates = vec![ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::CX, &[0, 2]), + gate(GateType::CX, &[1, 2]), + gate(GateType::MZ, &[2]), + ]; + + for &theta in &[0.01, 0.05, 0.1, 0.2, 0.3] { + let expanded = expand::expand_circuit(&gates); + let noise = NoiseModel::coherent_only(theta); + let result = analyze_expanded(&expanded.gates, &noise); + + let aux = expanded.measurement_qubit[0]; + let det = Detector { id: 0, stabilizer: Bm::z(aux) }; + let gates_pre = &gates[..gates.len() - 1]; + let stab_group = StabilizerGroup::from_circuit(gates_pre, expanded.num_original_qubits); + let entries = build_dem_with_stabilizers( + &result.generators, &[det], &[], Some(&stab_group), + ); + let eeg_prob: f64 = entries.iter().map(|e| e.probability).sum(); + + // StateVec + let mut det_count = 0u64; + let mut sim = StateVec::new(3); + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1), qid(2)]); + sim.cx(&[(qid(0), qid(2))]); + sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.cx(&[(qid(1), qid(2))]); + sim.rz(Angle64::from_radians(theta), &[qid(1)]); + sim.rz(Angle64::from_radians(theta), &[qid(2)]); + let r = sim.mz(&[qid(2)]); + if r[0].outcome { det_count += 1; } + } + + let sv = det_count as f64 / num_shots as f64; + let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + let ratio = if sv > 1e-10 { eeg_prob / sv } else { f64::NAN }; + + eprintln!("{theta:>8.3} {eeg_prob:>10.6} {sv:>10.6} {se:>10.6} {ratio:>10.4}"); + } +} + +// ============================================================ +// Repetition code comparison: EEG vs Heisenberg vs StateVec +// ============================================================ + +/// Build an X-check repetition code circuit. +/// +/// d data qubits, d-1 ancillas measuring X_i * X_{i+1} using +/// H-CX-CX-H on ancilla (sensitive to Z errors from coherent RZ noise). +/// `num_rounds` syndrome extraction rounds with reset. +/// Returns (gates, num_qubits, ancilla indices). +fn build_repetition_code(d: usize, num_rounds: usize) -> (Vec, usize, Vec) { + let num_data = d; + let num_ancilla = d - 1; + let num_qubits = num_data + num_ancilla; + + // Ancilla i checks X_{i} * X_{i+1}, located at qubit index d + i + let ancilla_start = num_data; + + let mut gates = Vec::new(); + + // Initialize all qubits + for q in 0..num_qubits { + gates.push(gate(GateType::PZ, &[q])); + } + + for round in 0..num_rounds { + // X-check: H(anc), CX(anc, data_i), CX(anc, data_{i+1}), H(anc), MZ(anc) + for i in 0..num_ancilla { + gates.push(gate(GateType::H, &[ancilla_start + i])); + } + for i in 0..num_ancilla { + let anc = ancilla_start + i; + gates.push(gate(GateType::CX, &[anc, i])); + } + for i in 0..num_ancilla { + let anc = ancilla_start + i; + gates.push(gate(GateType::CX, &[anc, i + 1])); + } + for i in 0..num_ancilla { + gates.push(gate(GateType::H, &[ancilla_start + i])); + } + + // Measure ancillas + for i in 0..num_ancilla { + gates.push(gate(GateType::MZ, &[ancilla_start + i])); + } + + // Reset ancillas (except last round) + if round < num_rounds - 1 { + for i in 0..num_ancilla { + gates.push(gate(GateType::PZ, &[ancilla_start + i])); + } + } + } + + // Final data readout + for q in 0..num_data { + gates.push(gate(GateType::MZ, &[q])); + } + + let ancillas: Vec = (0..num_ancilla).map(|i| ancilla_start + i).collect(); + (gates, num_qubits, ancillas) +} + +/// Repetition code: compare EEG (forward), Heisenberg (backward), and StateVec. +#[test] +#[ignore] +fn bench_repetition_code_comparison() { + use pecos_eeg::dem_mapping::EegConfig; + use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; + + let num_shots = 500_000; + let theta = 0.05; + + eprintln!("\n=== Repetition code: EEG vs Heisenberg vs StateVec ==="); + eprintln!("theta = {theta}, shots = {num_shots}"); + + for &d in &[3, 5] { + for &num_rounds in &[2, 3] { + let (gates, num_qubits, ancillas) = build_repetition_code(d, num_rounds); + let num_ancilla = ancillas.len(); + + // Measurement record layout: round 0 ancillas, round 1 ancillas, ..., data readout + // Round comparison detectors: meas[round*num_ancilla + i] XOR meas[(round+1)*num_ancilla + i] + let num_detectors = num_ancilla * (num_rounds - 1); + + eprintln!("\n d={d}, rounds={num_rounds}, qubits={num_qubits}, detectors={num_detectors}"); + + // --- EEG forward --- + let expanded = expand::expand_circuit(&gates); + let noise_model = NoiseModel::coherent_only(theta); + let noise_spec = UniformNoise::coherent_only(theta); + let result = analyze_expanded(&expanded.gates, &noise_model); + + let mut dets = Vec::new(); + for round in 0..(num_rounds - 1) { + for i in 0..num_ancilla { + let m1 = round * num_ancilla + i; + let m2 = (round + 1) * num_ancilla + i; + let aux1 = expanded.measurement_qubit[m1]; + let aux2 = expanded.measurement_qubit[m2]; + let mut stab = Bm::default(); + stab.z_bits.set_bit(aux1); + stab.z_bits.set_bit(aux2); + dets.push(Detector { id: dets.len(), stabilizer: stab }); + } + } + + let exp_pre: Vec<_> = { + let last = expanded.gates.iter().rposition(|g| g.gate_type != GateType::MZ).unwrap(); + expanded.gates[..=last].to_vec() + }; + let stab_group = StabilizerGroup::from_circuit(&exp_pre, expanded.num_qubits); + + let entries = pecos_eeg::dem_mapping::build_dem_configured( + &result.generators, &dets, &[], + Some(&stab_group), &EegConfig::default(), + ); + + let mut eeg_probs = vec![0.0; num_detectors]; + for e in &entries { + for &det_id in &e.event.detectors { + if det_id < num_detectors { + eeg_probs[det_id] += e.probability; + } + } + } + + // --- Heisenberg backward --- + let mut heis_probs = vec![0.0; num_detectors]; + for round in 0..(num_rounds - 1) { + for i in 0..num_ancilla { + let det_idx = round * num_ancilla + i; + let m1 = round * num_ancilla + i; + let m2 = (round + 1) * num_ancilla + i; + heis_probs[det_idx] = heisenberg_detection_probability_from_circuit( + &gates, &[m1, m2], &noise_spec, num_qubits, 1e-12, + ); + } + } + + // --- StateVec simulation --- + let mut sv_counts = vec![0u64; num_detectors]; + let mut sim = StateVec::new(num_qubits); + + for _ in 0..num_shots { + // Initialize + let all_qubits: Vec<_> = (0..num_qubits).map(qid).collect(); + sim.pz(&all_qubits); + + let mut meas_outcomes = Vec::new(); + + for round in 0..num_rounds { + // X-check: H(anc), CX(anc, data_i), CX(anc, data_{i+1}), H(anc) + let anc_qubits: Vec<_> = ancillas.iter().map(|&a| qid(a)).collect(); + sim.h(&anc_qubits); + + for i in 0..num_ancilla { + let anc = ancillas[i]; + sim.cx(&[(qid(anc), qid(i))]); + sim.rz(Angle64::from_radians(theta), &[qid(anc)]); + sim.rz(Angle64::from_radians(theta), &[qid(i)]); + } + for i in 0..num_ancilla { + let anc = ancillas[i]; + sim.cx(&[(qid(anc), qid(i + 1))]); + sim.rz(Angle64::from_radians(theta), &[qid(anc)]); + sim.rz(Angle64::from_radians(theta), &[qid(i + 1)]); + } + + sim.h(&anc_qubits); + + // Measure ancillas + for i in 0..num_ancilla { + let r = sim.mz(&[qid(ancillas[i])]); + meas_outcomes.push(r[0].outcome); + } + + // Reset (except last round) + if round < num_rounds - 1 { + sim.pz(&anc_qubits); + } + } + + // Count detector firings (round comparison) + for round in 0..(num_rounds - 1) { + for i in 0..num_ancilla { + let m1 = round * num_ancilla + i; + let m2 = (round + 1) * num_ancilla + i; + if meas_outcomes[m1] != meas_outcomes[m2] { + sv_counts[round * num_ancilla + i] += 1; + } + } + } + } + + // Print comparison + eprintln!(" {:>6} {:>10} {:>10} {:>10} {:>10} {:>10}", + "Det", "EEG", "Heisen", "StateVec", "SV_err", "H/SV"); + for det_idx in 0..num_detectors { + let sv_rate = sv_counts[det_idx] as f64 / num_shots as f64; + let sv_err = (sv_rate * (1.0 - sv_rate) / num_shots as f64).sqrt(); + let ratio = if sv_rate > 1e-10 { heis_probs[det_idx] / sv_rate } else { f64::NAN }; + let round = det_idx / num_ancilla; + let anc = det_idx % num_ancilla; + eprintln!(" R{round}A{anc} {:>10.6} {:>10.6} {:>10.6} {:>10.6} {:>10.4}", + eeg_probs[det_idx], heis_probs[det_idx], sv_rate, sv_err, ratio); + } + } + } +} + +/// KEY DIAGNOSTIC: Compare original-circuit StateVec, expanded-circuit StateVec, +/// and Heisenberg for the simplest failing case (weight-2, 2 rounds, 3 qubits). +/// +/// If expanded SV matches original SV: expansion is correct, Heisenberg has a bug. +/// If expanded SV differs: expansion is wrong. +#[test] +#[ignore] +fn bench_expansion_equivalence() { + use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; + + let num_shots = 1_000_000; + let theta = 0.05; + + eprintln!("\n=== Expansion equivalence: 3 qubits, 2 rounds ==="); + + // Original circuit with mid-circuit measurement + let gates_orig = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + ]; + + // Expand the circuit + let expanded = expand::expand_circuit(&gates_orig); + eprintln!("Expanded: {} gates, {} qubits", expanded.gates.len(), expanded.num_qubits); + eprintln!("Measurement map: {:?}", expanded.measurement_qubit); + for (i, g) in expanded.gates.iter().enumerate() { + let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + eprintln!(" [{i:2}] {:?}({qs:?})", g.gate_type); + } + + // --- Heisenberg on expanded circuit --- + let noise = UniformNoise::coherent_only(theta); + let h_p = heisenberg_detection_probability_from_circuit(&gates_orig, &[0, 1], &noise, 3, 0.0); + + // --- StateVec on ORIGINAL circuit (with mid-circuit measurements) --- + let mut orig_det = 0u64; + { + let mut sim = StateVec::new(3); + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1), qid(2)]); + let mut outs = [false; 2]; + for r in 0..2 { + sim.h(&[qid(2)]); + sim.cx(&[(qid(2), qid(0))]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.cx(&[(qid(2), qid(1))]); sim.rz(Angle64::from_radians(theta), &[qid(1)]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.h(&[qid(2)]); + outs[r] = sim.mz(&[qid(2)])[0].outcome; + if r == 0 { sim.pz(&[qid(2)]); } + } + if outs[0] != outs[1] { orig_det += 1; } + } + } + let sv_orig = orig_det as f64 / num_shots as f64; + + // --- StateVec on EXPANDED circuit (no mid-circuit measurements) --- + let mut exp_det = 0u64; + { + let num_exp_q = expanded.num_qubits; + let mut sim = StateVec::new(num_exp_q); + for _ in 0..num_shots { + // Execute the expanded circuit gate by gate + let all_q: Vec<_> = (0..num_exp_q).map(qid).collect(); + sim.pz(&all_q); + + for (i, g) in expanded.gates.iter().enumerate() { + let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + + // Skip expansion gates for noise (same logic as Heisenberg) + let is_exp_gate = { + let is_qalloc = g.gate_type == pecos_core::gate_type::GateType::QAlloc; + let is_exp_cx = i > 0 + && g.gate_type == pecos_core::gate_type::GateType::CX + && expanded.gates[i-1].gate_type == pecos_core::gate_type::GateType::QAlloc + && expanded.gates[i-1].qubits[0].index() == qs.get(1).copied().unwrap_or(999); + let is_exp_pz = i > 1 + && g.gate_type == pecos_core::gate_type::GateType::PZ + && expanded.gates[i-1].gate_type == pecos_core::gate_type::GateType::CX + && expanded.gates[i-2].gate_type == pecos_core::gate_type::GateType::QAlloc; + is_qalloc || is_exp_cx || is_exp_pz + }; + + match g.gate_type { + pecos_core::gate_type::GateType::PZ | pecos_core::gate_type::GateType::QAlloc => { + for &q in &qs { sim.pz(&[qid(q)]); } + } + pecos_core::gate_type::GateType::H => { + for &q in &qs { sim.h(&[qid(q)]); } + } + pecos_core::gate_type::GateType::CX => { + if qs.len() >= 2 { + sim.cx(&[(qid(qs[0]), qid(qs[1]))]); + } + } + pecos_core::gate_type::GateType::MZ => { + // Final measurement — handled below + } + _ => {} + } + + // Add noise after non-expansion CX gates + if !is_exp_gate && (g.gate_type == pecos_core::gate_type::GateType::CX) { + if qs.len() >= 2 { + sim.rz(Angle64::from_radians(theta), &[qid(qs[0])]); + sim.rz(Angle64::from_radians(theta), &[qid(qs[1])]); + } + } + } + + // Measure the two aux qubits + let aux0 = expanded.measurement_qubit[0]; + let aux1 = expanded.measurement_qubit[1]; + let r0 = sim.mz(&[qid(aux0)])[0].outcome; + let r1 = sim.mz(&[qid(aux1)])[0].outcome; + if r0 != r1 { exp_det += 1; } + } + } + let sv_exp = exp_det as f64 / num_shots as f64; + + // Exact analytical + let exact = (2.0 - (6.0 * theta).cos() - (2.0 * theta).cos()) / 4.0; + + let se_orig = (sv_orig * (1.0 - sv_orig) / num_shots as f64).sqrt(); + let se_exp = (sv_exp * (1.0 - sv_exp) / num_shots as f64).sqrt(); + + eprintln!("\nResults:"); + eprintln!(" Exact analytical: {exact:.6}"); + eprintln!(" SV original circuit: {sv_orig:.6} +/- {se_orig:.6}"); + eprintln!(" SV expanded circuit: {sv_exp:.6} +/- {se_exp:.6}"); + eprintln!(" Heisenberg: {h_p:.6}"); + eprintln!(" H/Exact = {:.4}", h_p / exact); + eprintln!(" SVexp/SVorig = {:.4}", sv_exp / sv_orig); +} + +/// Ground truth: compute the backward Heisenberg via DIRECT MATRIX MULTIPLICATION +/// on the expanded circuit. This bypasses the Pauli-tracking backward walk entirely. +/// +/// The detection probability is: +/// p = (1 - <0...0| O_backward |0...0>) / 2 +/// where O_backward = E_1† ... E_n†(D) +/// +/// We compute O_backward as a 2^n × 2^n matrix by multiplying the adjoint +/// of each gate/noise channel, then evaluate the diagonal element. +#[test] +#[ignore] +fn bench_matrix_heisenberg() { + use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; + + let theta = 0.05; + let n = 5; // qubits: q0,q1 data, q2 ancilla, q3 aux R1, q4 aux R2 + let dim = 1 << n; // 32 + + // The expanded circuit gates (from bench_expansion_equivalence) + let gates_orig = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + ]; + let expanded = expand::expand_circuit(&gates_orig); + + // Build the detector matrix: Z_3 * Z_4 + // Z_q has eigenvalue +1 for |0> and -1 for |1> + let mut obs = vec![0.0f64; dim * dim]; // real part (obs is Hermitian diagonal for Pauli Z) + for i in 0..dim { + let bit3 = (i >> 3) & 1; + let bit4 = (i >> 4) & 1; + let z3 = if bit3 == 0 { 1.0 } else { -1.0 }; + let z4 = if bit4 == 0 { 1.0 } else { -1.0 }; + obs[i * dim + i] = z3 * z4; + } + + // Now apply the adjoint of each gate/noise channel in REVERSE order. + // For unitary U: O → U† O U + // For PZ_q (reset): O → <0_q| O |0_q> tensored with I_q (extract q=0 block) + // For noise RZ(θ): O → RZ†(θ) O RZ(θ) (unitary conjugation) + // For MZ_q: O → project to Z eigenstates (diagonal on q) + + // Helper: build a gate matrix for the full n-qubit space + // We work with real+imaginary pairs: obs_re[i*dim+j], obs_im[i*dim+j] + let mut obs_re = vec![0.0f64; dim * dim]; + let mut obs_im = vec![0.0f64; dim * dim]; + for i in 0..dim { + let bit3 = (i >> 3) & 1; + let bit4 = (i >> 4) & 1; + obs_re[i * dim + i] = if bit3 == bit4 { 1.0 } else { -1.0 }; + } + + // Process gates in reverse order + let exp_gates_set = { + let mut s = std::collections::HashSet::new(); + // Detect expansion gates (same logic as heisenberg.rs) + for i in 1..expanded.gates.len() { + if expanded.gates[i].gate_type == pecos_core::gate_type::GateType::QAlloc { + s.insert(i); + } + if expanded.gates[i].gate_type == pecos_core::gate_type::GateType::CX + && expanded.gates[i-1].gate_type == pecos_core::gate_type::GateType::QAlloc + { + let aq = expanded.gates[i-1].qubits[0].index(); + if expanded.gates[i].qubits.len() >= 2 && expanded.gates[i].qubits[1].index() == aq { + s.insert(i); + if i+1 < expanded.gates.len() + && expanded.gates[i+1].gate_type == pecos_core::gate_type::GateType::PZ + && expanded.gates[i+1].qubits[0].index() == expanded.gates[i].qubits[0].index() + { + s.insert(i+1); + } + } + } + } + s + }; + + for idx in (0..expanded.gates.len()).rev() { + let g = &expanded.gates[idx]; + let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + + // Apply noise adjoint (if not expansion gate) + if !exp_gates_set.contains(&idx) { + match g.gate_type { + pecos_core::gate_type::GateType::CX => { + // idle_rz on both qubits + for &q in &qs { + apply_rz_adjoint(&mut obs_re, &mut obs_im, q, theta, n); + } + } + _ => {} + } + } + + // Apply gate adjoint + match g.gate_type { + pecos_core::gate_type::GateType::PZ | pecos_core::gate_type::GateType::QAlloc => { + // PZ†(O) = <0_q| O |0_q> ⊗ I_q + // This zeros all matrix elements where q is in state |1> + // and copies q=0 block to the full matrix + apply_pz_adjoint(&mut obs_re, &mut obs_im, qs[0], n); + } + pecos_core::gate_type::GateType::MZ => { + // MZ†(O) = Σ_m |m> { + apply_h_adjoint(&mut obs_re, &mut obs_im, qs[0], n); + } + pecos_core::gate_type::GateType::CX => { + apply_cx_adjoint(&mut obs_re, &mut obs_im, qs[0], qs[1], n); + } + _ => {} + } + } + + // Evaluate <0...0| O_backward |0...0> + let expectation = obs_re[0]; // |0...0> is index 0 + let matrix_detection = 0.5 * (1.0 - expectation); + + // Step-by-step matrix trace: print <0|O|0> after each gate + // Re-run with printing + { + let mut tr_re = vec![0.0f64; dim * dim]; + let mut tr_im = vec![0.0f64; dim * dim]; + for i in 0..dim { + let bit3 = (i >> 3) & 1; + let bit4 = (i >> 4) & 1; + tr_re[i * dim + i] = if bit3 == bit4 { 1.0 } else { -1.0 }; + } + + eprintln!("\n Step-by-step <0|O|0> comparison (matrix vs walk):"); + eprintln!(" {:>4} {:>20} {:>12}", "Gate", "Description", "Matrix<0|O|0>"); + + for idx in (0..expanded.gates.len()).rev() { + let g = &expanded.gates[idx]; + let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + let is_exp = exp_gates_set.contains(&idx); + + if !is_exp { + if g.gate_type == pecos_core::gate_type::GateType::CX && qs.len() >= 2 { + for &q in &qs { + apply_rz_adjoint(&mut tr_re, &mut tr_im, q, theta, n); + } + } + } + + match g.gate_type { + pecos_core::gate_type::GateType::PZ | pecos_core::gate_type::GateType::QAlloc => { + apply_pz_adjoint(&mut tr_re, &mut tr_im, qs[0], n); + } + pecos_core::gate_type::GateType::MZ => { + apply_mz_adjoint(&mut tr_re, &mut tr_im, qs[0], n); + } + pecos_core::gate_type::GateType::H => { + apply_h_adjoint(&mut tr_re, &mut tr_im, qs[0], n); + } + pecos_core::gate_type::GateType::CX => { + apply_cx_adjoint(&mut tr_re, &mut tr_im, qs[0], qs[1], n); + } + _ => {} + } + + let e = tr_re[0]; + let tag = if is_exp { " [EXP]" } else { "" }; + eprintln!(" [{idx:>2}] {:?}({qs:?}){tag}: {e:.10}", + g.gate_type); + } + } + + // Heisenberg backward walk + let noise = UniformNoise::coherent_only(theta); + let h_p = heisenberg_detection_probability_from_circuit(&gates_orig, &[0, 1], &noise, 3, 0.0); + + // Exact analytical + let exact = (2.0 - (6.0 * theta).cos() - (2.0 * theta).cos()) / 4.0; + + eprintln!("\n=== Matrix Heisenberg ground truth ==="); + eprintln!(" Exact analytical: {exact:.10}"); + eprintln!(" Matrix Heisenberg: {matrix_detection:.10}"); + eprintln!(" Backward walk: {h_p:.10}"); + eprintln!(" Matrix/Exact: {:.6}", matrix_detection / exact); + eprintln!(" Walk/Matrix: {:.6}", h_p / matrix_detection); +} + +// Matrix helpers for n-qubit system +fn apply_rz_adjoint(re: &mut [f64], im: &mut [f64], q: usize, theta: f64, n: usize) { + let dim = 1 << n; + // For each matrix element O[i,j]: + // New O[i,j] = e^{i(b_i - b_j)θ/2} · O[i,j] + // where b_i = bit q of i (0 → phase -θ/2, 1 → phase +θ/2) + for i in 0..dim { + let bi = ((i >> q) & 1) as f64; // 0 or 1 + for j in 0..dim { + let bj = ((j >> q) & 1) as f64; + let phase = (bi - bj) * theta; // phase angle + if phase.abs() < 1e-20 { continue; } + let cp = phase.cos(); + let sp = phase.sin(); + let idx = i * dim + j; + let r = re[idx]; + let m = im[idx]; + re[idx] = cp * r - sp * m; + im[idx] = sp * r + cp * m; + } + } +} + +fn apply_pz_adjoint(re: &mut [f64], im: &mut [f64], q: usize, n: usize) { + // PZ†(O) = Σ_m |m⟩⟨0| O |0⟩⟨m| where K_m = |0⟩⟨m| + // Matrix elements: [PZ†(O)]_{ij} = δ(i_q, j_q) · O_{(i with q=0), (j with q=0)} + // Off-diagonal elements (where qubit q differs) are ZERO. + let dim = 1 << n; + let mask = 1 << q; + for i in 0..dim { + let iq = (i >> q) & 1; + for j in 0..dim { + let jq = (j >> q) & 1; + let idx = i * dim + j; + if iq != jq { + re[idx] = 0.0; + im[idx] = 0.0; + } else { + let i0 = i & !mask; + let j0 = j & !mask; + let idx0 = i0 * dim + j0; + re[idx] = re[idx0]; + im[idx] = im[idx0]; + } + } + } +} + +fn apply_mz_adjoint(re: &mut [f64], im: &mut [f64], q: usize, n: usize) { + let dim = 1 << n; + for i in 0..dim { + let bi = (i >> q) & 1; + for j in 0..dim { + let bj = (j >> q) & 1; + if bi != bj { + let idx = i * dim + j; + re[idx] = 0.0; + im[idx] = 0.0; + } + } + } +} + +fn apply_h_adjoint(re: &mut [f64], im: &mut [f64], q: usize, n: usize) { + // H† O H = H O H (H is self-adjoint) + // H|0> = (|0>+|1>)/√2, H|1> = (|0>-|1>)/√2 + let dim = 1 << n; + let mask = 1 << q; + // For each pair (i, i^mask), apply the 2x2 Hadamard conjugation + // O' = H ⊗ I · O · H ⊗ I + // This swaps/combines rows and columns corresponding to bit q + let mut new_re = vec![0.0; dim * dim]; + let mut new_im = vec![0.0; dim * dim]; + for i in 0..dim { + for j in 0..dim { + // new O[i,j] = Σ_{a,b} H[i_q,a] O[i_with_a, j_with_b] H[b, j_q] + let i0 = i & !mask; + let i1 = i | mask; + let j0 = j & !mask; + let j1 = j | mask; + let iq = (i >> q) & 1; + let jq = (j >> q) & 1; + // H[0,0]=1/√2, H[0,1]=1/√2, H[1,0]=1/√2, H[1,1]=-1/√2 + // H[x,y] = (1/√2)(-1)^{xy} + // H[iq,a]*H[b,jq] = (1/2)(-1)^{iq*a+b*jq} + let mut sum_r = 0.0; + let mut sum_i = 0.0; + for a in 0..2usize { + for b in 0..2usize { + let ia = if a == 0 { i0 } else { i1 }; + let jb = if b == 0 { j0 } else { j1 }; + let idx = ia * dim + jb; + let sign = if (iq * a + b * jq) % 2 == 0 { 1.0 } else { -1.0 }; + let c = 0.5 * sign; + sum_r += c * re[idx]; + sum_i += c * im[idx]; + } + } + new_re[i * dim + j] = sum_r; + new_im[i * dim + j] = sum_i; + } + } + re.copy_from_slice(&new_re); + im.copy_from_slice(&new_im); +} + +fn apply_cx_adjoint(re: &mut [f64], im: &mut [f64], control: usize, target: usize, n: usize) { + // CX† O CX = CX O CX (CX is self-adjoint) + // CX flips target when control=1: CX|c,t> = |c, c⊕t> + let dim = 1 << n; + let cmask = 1 << control; + let tmask = 1 << target; + // CX permutation: state index i maps to i ^ (tmask if control bit set) + let cx_perm = |i: usize| -> usize { + if (i & cmask) != 0 { i ^ tmask } else { i } + }; + // O' = CX · O · CX: new O[i,j] = O[CX(i), CX(j)] + let mut new_re = vec![0.0; dim * dim]; + let mut new_im = vec![0.0; dim * dim]; + for i in 0..dim { + let ci = cx_perm(i); + for j in 0..dim { + let cj = cx_perm(j); + new_re[i * dim + j] = re[ci * dim + cj]; + new_im[i * dim + j] = im[ci * dim + cj]; + } + } + re.copy_from_slice(&new_re); + im.copy_from_slice(&new_im); +} + +/// Per-noise-source attribution: which noise sources does the backward walk miss? +/// +/// Enable one noise source at a time and compare matrix vs backward walk. +#[test] +#[ignore] +fn bench_per_noise_attribution() { + use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; + + let theta = 0.05; + let n = 5; + let dim = 1 << n; + + let gates_orig = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + ]; + let expanded = expand::expand_circuit(&gates_orig); + + // Noise source locations in expanded circuit: + // Gate 4: CX(2,0) R1 → noise on q2 and q0 + // Gate 5: CX(2,1) R1 → noise on q2 and q1 + // Gate 12: CX(2,0) R2 → noise on q2 and q0 + // Gate 13: CX(2,1) R2 → noise on q2 and q1 + let noise_sources = [ + (4, 2, "R1 CX(2,0) Z2"), + (4, 0, "R1 CX(2,0) Z0"), + (5, 2, "R1 CX(2,1) Z2"), + (5, 1, "R1 CX(2,1) Z1"), + (12, 2, "R2 CX(2,0) Z2"), + (12, 0, "R2 CX(2,0) Z0"), + (13, 2, "R2 CX(2,1) Z2"), + (13, 1, "R2 CX(2,1) Z1"), + ]; + + eprintln!("\n=== Per-noise-source attribution ==="); + eprintln!("{:>25} {:>12} {:>12} {:>8}", "Source", "Matrix", "Walk", "Ratio"); + + for &(gate_idx, qubit, label) in &noise_sources { + // Matrix computation with only this one noise source + let mut obs_re = vec![0.0f64; dim * dim]; + let mut obs_im = vec![0.0f64; dim * dim]; + for i in 0..dim { + let bit3 = (i >> 3) & 1; + let bit4 = (i >> 4) & 1; + obs_re[i * dim + i] = if bit3 == bit4 { 1.0 } else { -1.0 }; + } + + // Process gates in reverse, only applying noise for the specified source + for idx in (0..expanded.gates.len()).rev() { + let g = &expanded.gates[idx]; + let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + + // Noise: only the specified source + if idx == gate_idx { + apply_rz_adjoint(&mut obs_re, &mut obs_im, qubit, theta, n); + } + + // Gate adjoint (always) + match g.gate_type { + pecos_core::gate_type::GateType::PZ | pecos_core::gate_type::GateType::QAlloc => { + apply_pz_adjoint(&mut obs_re, &mut obs_im, qs[0], n); + } + pecos_core::gate_type::GateType::MZ => { + apply_mz_adjoint(&mut obs_re, &mut obs_im, qs[0], n); + } + pecos_core::gate_type::GateType::H => { + apply_h_adjoint(&mut obs_re, &mut obs_im, qs[0], n); + } + pecos_core::gate_type::GateType::CX => { + apply_cx_adjoint(&mut obs_re, &mut obs_im, qs[0], qs[1], n); + } + _ => {} + } + } + + let matrix_p = 0.5 * (1.0 - obs_re[0]); + + // Backward walk: use a custom noise spec that only injects at the specified source + // (We can't easily do this with the public API, so just report the matrix result.) + eprintln!("{label:>25} {matrix_p:>12.8} {:>12} {:>8}", "-", "-"); + } + + // Also show all-noise results + let mut obs_re = vec![0.0f64; dim * dim]; + let mut obs_im = vec![0.0f64; dim * dim]; + for i in 0..dim { + let bit3 = (i >> 3) & 1; + let bit4 = (i >> 4) & 1; + obs_re[i * dim + i] = if bit3 == bit4 { 1.0 } else { -1.0 }; + } + for idx in (0..expanded.gates.len()).rev() { + let g = &expanded.gates[idx]; + let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + if g.gate_type == pecos_core::gate_type::GateType::CX && qs.len() >= 2 { + // Check if expansion gate + let is_exp = idx > 0 + && expanded.gates[idx-1].gate_type == pecos_core::gate_type::GateType::QAlloc + && expanded.gates[idx-1].qubits[0].index() == qs[1]; + if !is_exp { + apply_rz_adjoint(&mut obs_re, &mut obs_im, qs[0], theta, n); + apply_rz_adjoint(&mut obs_re, &mut obs_im, qs[1], theta, n); + } + } + match g.gate_type { + pecos_core::gate_type::GateType::PZ | pecos_core::gate_type::GateType::QAlloc => { + apply_pz_adjoint(&mut obs_re, &mut obs_im, qs[0], n); + } + pecos_core::gate_type::GateType::MZ => { + apply_mz_adjoint(&mut obs_re, &mut obs_im, qs[0], n); + } + pecos_core::gate_type::GateType::H => { + apply_h_adjoint(&mut obs_re, &mut obs_im, qs[0], n); + } + pecos_core::gate_type::GateType::CX => { + apply_cx_adjoint(&mut obs_re, &mut obs_im, qs[0], qs[1], n); + } + _ => {} + } + } + let matrix_all = 0.5 * (1.0 - obs_re[0]); + let noise = UniformNoise::coherent_only(theta); + let walk_all = heisenberg_detection_probability_from_circuit(&gates_orig, &[0, 1], &noise, 3, 0.0); + eprintln!("{:>25} {:>12.8} {:>12.8} {:>8.4}", "ALL", matrix_all, walk_all, walk_all / matrix_all); +} + +/// Isolate weight-2 vs weight-4 X-check, single vs multi-round. +#[test] +#[ignore] +fn bench_weight_isolation() { + use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; + + let num_shots = 500_000; + let theta = 0.05; + + eprintln!("\n=== Weight isolation: single ancilla, no shared qubits ==="); + eprintln!("theta = {theta}, shots = {num_shots}\n"); + + // ---- Weight-2, 1 round: H(2), CX(2,0), CX(2,1), H(2), MZ(2) ---- + { + let gates = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + ]; + let noise = UniformNoise::coherent_only(theta); + let h_p = heisenberg_detection_probability_from_circuit(&gates, &[0], &noise, 3, 0.0); + + let mut det = 0u64; + let mut sim = StateVec::new(3); + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1), qid(2)]); + sim.h(&[qid(2)]); + sim.cx(&[(qid(2), qid(0))]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.cx(&[(qid(2), qid(1))]); sim.rz(Angle64::from_radians(theta), &[qid(1)]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.h(&[qid(2)]); + if sim.mz(&[qid(2)])[0].outcome { det += 1; } + } + let sv = det as f64 / num_shots as f64; + let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + eprintln!("Wt-2 1rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", if sv > 1e-10 { h_p/sv } else { f64::NAN }); + } + + // ---- Weight-2, 2 rounds: round comparison ---- + { + let gates = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), gate(GateType::CX, &[2, 0]), gate(GateType::CX, &[2, 1]), gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), gate(GateType::CX, &[2, 0]), gate(GateType::CX, &[2, 1]), gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + ]; + let noise = UniformNoise::coherent_only(theta); + let h_p = heisenberg_detection_probability_from_circuit(&gates, &[0, 1], &noise, 3, 0.0); + + let mut det = 0u64; + let mut sim = StateVec::new(3); + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1), qid(2)]); + let mut outs = [false; 2]; + for r in 0..2 { + sim.h(&[qid(2)]); + sim.cx(&[(qid(2), qid(0))]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.cx(&[(qid(2), qid(1))]); sim.rz(Angle64::from_radians(theta), &[qid(1)]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.h(&[qid(2)]); + outs[r] = sim.mz(&[qid(2)])[0].outcome; + if r == 0 { sim.pz(&[qid(2)]); } + } + if outs[0] != outs[1] { det += 1; } + } + let sv = det as f64 / num_shots as f64; + let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + eprintln!("Wt-2 2rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", if sv > 1e-10 { h_p/sv } else { f64::NAN }); + } + + // ---- Weight-4, 1 round ---- + { + let gates = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), gate(GateType::PZ, &[3]), gate(GateType::PZ, &[4]), + gate(GateType::H, &[4]), + gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[4, 2]), gate(GateType::CX, &[4, 3]), + gate(GateType::H, &[4]), + gate(GateType::MZ, &[4]), + ]; + let noise = UniformNoise::coherent_only(theta); + let h_p = heisenberg_detection_probability_from_circuit(&gates, &[0], &noise, 5, 0.0); + + let mut det = 0u64; + let mut sim = StateVec::new(5); + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1), qid(2), qid(3), qid(4)]); + sim.h(&[qid(4)]); + for &d in &[0usize, 1, 2, 3] { + sim.cx(&[(qid(4), qid(d))]); sim.rz(Angle64::from_radians(theta), &[qid(4)]); sim.rz(Angle64::from_radians(theta), &[qid(d)]); + } + sim.h(&[qid(4)]); + if sim.mz(&[qid(4)])[0].outcome { det += 1; } + } + let sv = det as f64 / num_shots as f64; + let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + eprintln!("Wt-4 1rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", if sv > 1e-10 { h_p/sv } else { f64::NAN }); + } + + // ---- Weight-4, 2 rounds ---- + { + let gates = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), gate(GateType::PZ, &[3]), gate(GateType::PZ, &[4]), + gate(GateType::H, &[4]), + gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[4, 2]), gate(GateType::CX, &[4, 3]), + gate(GateType::H, &[4]), + gate(GateType::MZ, &[4]), gate(GateType::PZ, &[4]), + gate(GateType::H, &[4]), + gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[4, 2]), gate(GateType::CX, &[4, 3]), + gate(GateType::H, &[4]), + gate(GateType::MZ, &[4]), + ]; + let noise = UniformNoise::coherent_only(theta); + let h_p = heisenberg_detection_probability_from_circuit(&gates, &[0, 1], &noise, 5, 0.0); + + let mut det = 0u64; + let mut sim = StateVec::new(5); + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1), qid(2), qid(3), qid(4)]); + let mut outs = [false; 2]; + for r in 0..2 { + sim.h(&[qid(4)]); + for &d in &[0usize, 1, 2, 3] { + sim.cx(&[(qid(4), qid(d))]); sim.rz(Angle64::from_radians(theta), &[qid(4)]); sim.rz(Angle64::from_radians(theta), &[qid(d)]); + } + sim.h(&[qid(4)]); + outs[r] = sim.mz(&[qid(4)])[0].outcome; + if r == 0 { sim.pz(&[qid(4)]); } + } + if outs[0] != outs[1] { det += 1; } + } + let sv = det as f64 / num_shots as f64; + let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + eprintln!("Wt-4 2rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", if sv > 1e-10 { h_p/sv } else { f64::NAN }); + } + + eprintln!(); + // ---- 2 weight-2 ancillas sharing a data qubit, 2 rounds ---- + { + let gates = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[3]), gate(GateType::PZ, &[4]), + // Round 1 + gate(GateType::H, &[3]), gate(GateType::H, &[4]), + gate(GateType::CX, &[3, 0]), gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[3, 1]), gate(GateType::CX, &[4, 2]), + gate(GateType::H, &[3]), gate(GateType::H, &[4]), + gate(GateType::MZ, &[3]), gate(GateType::MZ, &[4]), + gate(GateType::PZ, &[3]), gate(GateType::PZ, &[4]), + // Round 2 + gate(GateType::H, &[3]), gate(GateType::H, &[4]), + gate(GateType::CX, &[3, 0]), gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[3, 1]), gate(GateType::CX, &[4, 2]), + gate(GateType::H, &[3]), gate(GateType::H, &[4]), + gate(GateType::MZ, &[3]), gate(GateType::MZ, &[4]), + ]; + let noise = UniformNoise::coherent_only(theta); + let h_a0 = heisenberg_detection_probability_from_circuit(&gates, &[0, 2], &noise, 5, 0.0); + let h_a1 = heisenberg_detection_probability_from_circuit(&gates, &[1, 3], &noise, 5, 0.0); + + let mut a0 = 0u64; + let mut a1 = 0u64; + let mut sim = StateVec::new(5); + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1), qid(2), qid(3), qid(4)]); + let mut outs = [false; 4]; // [r0a0, r0a1, r1a0, r1a1] + for r in 0..2 { + sim.h(&[qid(3), qid(4)]); + sim.cx(&[(qid(3), qid(0))]); sim.rz(Angle64::from_radians(theta), &[qid(3)]); sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.cx(&[(qid(4), qid(1))]); sim.rz(Angle64::from_radians(theta), &[qid(4)]); sim.rz(Angle64::from_radians(theta), &[qid(1)]); + sim.cx(&[(qid(3), qid(1))]); sim.rz(Angle64::from_radians(theta), &[qid(3)]); sim.rz(Angle64::from_radians(theta), &[qid(1)]); + sim.cx(&[(qid(4), qid(2))]); sim.rz(Angle64::from_radians(theta), &[qid(4)]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.h(&[qid(3), qid(4)]); + outs[r * 2] = sim.mz(&[qid(3)])[0].outcome; + outs[r * 2 + 1] = sim.mz(&[qid(4)])[0].outcome; + if r == 0 { sim.pz(&[qid(3), qid(4)]); } + } + if outs[0] != outs[2] { a0 += 1; } + if outs[1] != outs[3] { a1 += 1; } + } + let sv0 = a0 as f64 / num_shots as f64; + let sv1 = a1 as f64 / num_shots as f64; + let se0 = (sv0 * (1.0 - sv0) / num_shots as f64).sqrt(); + let se1 = (sv1 * (1.0 - sv1) / num_shots as f64).sqrt(); + eprintln!("Shared A0: H={h_a0:.6} SV={sv0:.6}+/-{se0:.6} H/SV={:.4}", if sv0 > 1e-10 { h_a0/sv0 } else { f64::NAN }); + eprintln!("Shared A1: H={h_a1:.6} SV={sv1:.6}+/-{se1:.6} H/SV={:.4}", if sv1 > 1e-10 { h_a1/sv1 } else { f64::NAN }); + } +} + +/// Measure how Heisenberg backward walk cost scales with surface code distance and rounds. +/// +/// The backward walk creates 2^m terms where m is the number of anticommuting +/// noise sources per detector. For larger codes, m grows, making the walk +/// exponentially more expensive. +/// +/// We measure ALL round-comparison detectors and report per-detector timing, +/// since boundary detectors (ancilla 0/last) only couple to 2 CX gates while +/// bulk detectors (middle ancillas) couple to 4, seeing more noise sources. +#[test] +#[ignore] +fn bench_heisenberg_scaling() { + use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; + use std::time::Instant; + + let theta = 0.05; + + // --- Part 1: Vary distance at fixed rounds=2 --- + eprintln!("\n=== Heisenberg scaling: distance sweep (rounds=2, all detectors) ==="); + eprintln!("{:>4} {:>10} {:>14} {:>6} {:>18} {:>12} {:>12} {:>12}", + "d", "num_qubits", "expanded_q", "n_det", "max_prob", "max_ms", "total_ms", "per_det_ms"); + + for &d in &[3, 5, 7, 9] { + let num_rounds = 2; + let (gates, num_qubits, _ancillas) = build_repetition_code(d, num_rounds); + let num_ancilla = d - 1; + let num_detectors = num_ancilla; // rounds-1 == 1 comparison per ancilla + + let expanded = expand::expand_circuit(&gates); + let noise = UniformNoise::coherent_only(theta); + + let mut max_prob = 0.0f64; + let mut max_ms = 0.0f64; + let mut total_ms = 0.0f64; + + eprintln!(" d={d} per-detector detail:"); + eprintln!(" {:>6} {:>18} {:>12}", "det", "prob", "time_ms"); + + for i in 0..num_detectors { + // Round comparison: meas record i (round 0) vs i + num_ancilla (round 1) + let m1 = i; + let m2 = i + num_ancilla; + + let start = Instant::now(); + let prob = heisenberg_detection_probability_from_circuit( + &gates, &[m1, m2], &noise, num_qubits, 0.0, + ); + let elapsed_ms = start.elapsed().as_secs_f64() * 1000.0; + + eprintln!(" {:>6} {prob:>18.10} {elapsed_ms:>12.2}", i); + + max_prob = max_prob.max(prob); + max_ms = max_ms.max(elapsed_ms); + total_ms += elapsed_ms; + } + + let per_det = total_ms / num_detectors as f64; + eprintln!("{d:>4} {num_qubits:>10} {:>14} {num_detectors:>6} {max_prob:>18.10} {max_ms:>12.2} {total_ms:>12.2} {per_det:>12.2}", + expanded.num_qubits); + } + + // --- Part 2: Vary rounds at fixed d=3 --- + eprintln!("\n=== Heisenberg scaling: rounds sweep (d=3, all detectors) ==="); + eprintln!("{:>6} {:>10} {:>14} {:>6} {:>18} {:>12} {:>12} {:>12}", + "rounds", "num_qubits", "expanded_q", "n_det", "max_prob", "max_ms", "total_ms", "per_det_ms"); + + for &num_rounds in &[2, 3, 4, 5] { + let d = 3; + let (gates, num_qubits, _ancillas) = build_repetition_code(d, num_rounds); + let num_ancilla = d - 1; + // Round comparison detectors: (num_rounds - 1) comparisons per ancilla + let num_detectors = num_ancilla * (num_rounds - 1); + + let expanded = expand::expand_circuit(&gates); + let noise = UniformNoise::coherent_only(theta); + + let mut max_prob = 0.0f64; + let mut max_ms = 0.0f64; + let mut total_ms = 0.0f64; + + eprintln!(" rounds={num_rounds} per-detector detail:"); + eprintln!(" {:>6} {:>18} {:>12}", "det", "prob", "time_ms"); + + for round in 0..(num_rounds - 1) { + for i in 0..num_ancilla { + let m1 = round * num_ancilla + i; + let m2 = (round + 1) * num_ancilla + i; + + let start = Instant::now(); + let prob = heisenberg_detection_probability_from_circuit( + &gates, &[m1, m2], &noise, num_qubits, 0.0, + ); + let elapsed_ms = start.elapsed().as_secs_f64() * 1000.0; + + eprintln!(" R{}A{} {prob:>18.10} {elapsed_ms:>12.2}", round, i); + + max_prob = max_prob.max(prob); + max_ms = max_ms.max(elapsed_ms); + total_ms += elapsed_ms; + } + } + + let per_det = total_ms / num_detectors as f64; + eprintln!("{num_rounds:>6} {num_qubits:>10} {:>14} {num_detectors:>6} {max_prob:>18.10} {max_ms:>12.2} {total_ms:>12.2} {per_det:>12.2}", + expanded.num_qubits); + } +} + +/// Combined coherent + stochastic noise on a Wt-2 2-round X-check circuit. +/// +/// Uses `idle_rz=0.05` (coherent RZ after each CX) plus `p_meas=0.003` +/// (measurement bit-flip). The Heisenberg walk handles both H-type and +/// S-type generators in a single backward pass. +/// +/// StateVec applies identical noise: RZ(theta) on both qubits after each +/// CX, and flips the MZ outcome with probability p_meas. +/// +/// Detector: round-comparison (meas[0] XOR meas[1]). +#[test] +#[ignore] +fn bench_combined_noise() { + use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; + use pecos_random::PecosRng; + use pecos_random::rng_ext::RngProbabilityExt; + + let idle_rz = 0.05; + let p_meas = 0.003; + let num_shots = 500_000; + + eprintln!("\n=== Combined coherent + stochastic noise: Wt-2 2-round X-check ==="); + eprintln!("idle_rz = {idle_rz}, p_meas = {p_meas}, shots = {num_shots}\n"); + + // ---- Build the circuit: 2 data (q0,q1) + 1 ancilla (q2), 2 rounds ---- + let gates = vec![ + gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + // Round 1 + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + gate(GateType::PZ, &[2]), + // Round 2 + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + ]; + + // ---- Heisenberg walk with combined noise ---- + let noise = UniformNoise { idle_rz, p1: 0.0, p2: 0.0, p_meas, p_prep: 0.0 }; + // Detector = Z on meas[0] * Z on meas[1] (round comparison) + let h_p = heisenberg_detection_probability_from_circuit(&gates, &[0, 1], &noise, 3, 0.0); + + // ---- Also compute coherent-only and meas-only for decomposition ---- + let noise_coh = UniformNoise::coherent_only(idle_rz); + let h_coh = heisenberg_detection_probability_from_circuit(&gates, &[0, 1], &noise_coh, 3, 0.0); + + let noise_meas = UniformNoise { idle_rz: 0.0, p1: 0.0, p2: 0.0, p_meas, p_prep: 0.0 }; + let h_meas = heisenberg_detection_probability_from_circuit(&gates, &[0, 1], &noise_meas, 3, 0.0); + + // ---- StateVec simulation with matching noise ---- + let mut rng = PecosRng::seed_from_u64(12345); + let meas_threshold = rng.probability_threshold(p_meas); + + let mut det = 0u64; + let mut sim = StateVec::new(3); + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1), qid(2)]); + let mut outs = [false; 2]; + for r in 0..2 { + sim.h(&[qid(2)]); + // CX(2,0) + idle RZ noise + sim.cx(&[(qid(2), qid(0))]); + sim.rz(Angle64::from_radians(idle_rz), &[qid(2)]); + sim.rz(Angle64::from_radians(idle_rz), &[qid(0)]); + // CX(2,1) + idle RZ noise + sim.cx(&[(qid(2), qid(1))]); + sim.rz(Angle64::from_radians(idle_rz), &[qid(1)]); + sim.rz(Angle64::from_radians(idle_rz), &[qid(2)]); + sim.h(&[qid(2)]); + // MZ with measurement error + let mut outcome = sim.mz(&[qid(2)])[0].outcome; + if rng.check_probability(meas_threshold) { + outcome = !outcome; + } + outs[r] = outcome; + if r == 0 { sim.pz(&[qid(2)]); } + } + if outs[0] != outs[1] { det += 1; } + } + let sv = det as f64 / num_shots as f64; + let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + let ratio = if sv > 1e-10 { h_p / sv } else { f64::NAN }; + + eprintln!("Heisenberg (combined): {h_p:.6}"); + eprintln!("Heisenberg (coh only): {h_coh:.6}"); + eprintln!("Heisenberg (meas only):{h_meas:.6}"); + eprintln!("StateVec: {sv:.6} +/- {se:.6}"); + eprintln!("H/SV ratio: {ratio:.4}"); + eprintln!(); + + // ---- Sweep p_meas to see how combined noise scales ---- + eprintln!("{:>8} {:>10} {:>10} {:>10} {:>10}", + "p_meas", "H_comb", "SV", "SV_stderr", "H/SV"); + + for &pm in &[0.0, 0.001, 0.003, 0.005, 0.01, 0.02, 0.05] { + let n = UniformNoise { idle_rz, p1: 0.0, p2: 0.0, p_meas: pm, p_prep: 0.0 }; + let hp = heisenberg_detection_probability_from_circuit(&gates, &[0, 1], &n, 3, 0.0); + + let pm_threshold = rng.probability_threshold(pm); + let mut d = 0u64; + for _ in 0..num_shots { + sim.pz(&[qid(0), qid(1), qid(2)]); + let mut os = [false; 2]; + for r in 0..2 { + sim.h(&[qid(2)]); + sim.cx(&[(qid(2), qid(0))]); + sim.rz(Angle64::from_radians(idle_rz), &[qid(2)]); + sim.rz(Angle64::from_radians(idle_rz), &[qid(0)]); + sim.cx(&[(qid(2), qid(1))]); + sim.rz(Angle64::from_radians(idle_rz), &[qid(1)]); + sim.rz(Angle64::from_radians(idle_rz), &[qid(2)]); + sim.h(&[qid(2)]); + let mut out = sim.mz(&[qid(2)])[0].outcome; + if rng.check_probability(pm_threshold) { + out = !out; + } + os[r] = out; + if r == 0 { sim.pz(&[qid(2)]); } + } + if os[0] != os[1] { d += 1; } + } + let s = d as f64 / num_shots as f64; + let e = (s * (1.0 - s) / num_shots as f64).sqrt(); + let r = if s > 1e-10 { hp / s } else { f64::NAN }; + eprintln!("{pm:>8.4} {hp:>10.6} {s:>10.6} {e:>10.6} {r:>10.4}"); + } +} diff --git a/exp/pecos-eeg/tests/strong_sim_validation.rs b/exp/pecos-eeg/tests/strong_sim_validation.rs new file mode 100644 index 000000000..1cf2edb9e --- /dev/null +++ b/exp/pecos-eeg/tests/strong_sim_validation.rs @@ -0,0 +1,228 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Validation tests for approximate strong simulation. + +use pecos_eeg::Bm; +use pecos_eeg::circuit::PropagatedEeg; +use pecos_eeg::eeg::EegType; +use pecos_eeg::strong_sim::outcome_probability; + +/// H-type correction: |0⟩ with H_X gives p(1) = h² at leading order. +/// Cross-check: exact p(1) = sin²(h). +#[test] +fn test_h_correction_matches_exact() { + let stabs = vec![Bm::z(0)]; + + for &h in &[0.01, 0.05, 0.1, 0.2] { + let gens = vec![PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: h, + source: None, + }]; + + let p1 = outcome_probability(&gens, &[true], &stabs); + let exact = h.sin().powi(2); + + // EEG gives h², which ≈ sin²(h) for small h + assert!((p1.total - h * h).abs() < 1e-10, + "h={h}: EEG p(1)={:.6} expected h²={:.6}", p1.total, h * h); + + // Check closeness to exact + let rel_err = (p1.total - exact).abs() / exact; + eprintln!("h={h:.2}: EEG={:.6} exact={exact:.6} rel_err={rel_err:.4}", p1.total); + if h <= 0.1 { + assert!(rel_err < 0.02, "h={h}: relative error {rel_err:.4} > 2%"); + } + } +} + +/// Probability conservation: p(0) + p(1) = 1 at leading order for H-type. +#[test] +fn test_h_probability_conservation() { + let stabs = vec![Bm::z(0)]; + let h = 0.1; + + let gens = vec![PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: h, + source: None, + }]; + + let p0 = outcome_probability(&gens, &[false], &stabs); + let p1 = outcome_probability(&gens, &[true], &stabs); + let sum = p0.total + p1.total; + + assert!((sum - 1.0).abs() < 0.001, + "p(0)+p(1) = {sum:.6}, expected ≈ 1.0"); +} + +/// Bell state: H_{Z0} noise should NOT affect Z-basis measurement probabilities. +/// (Z commutes with Z-basis measurements.) +#[test] +fn test_bell_h_z_invisible() { + let stabs = vec![ + Bm::x(0).multiply(&Bm::x(1)), // XX + Bm::z(0).multiply(&Bm::z(1)), // ZZ + ]; + + let gens = vec![PropagatedEeg { + eeg_type: EegType::H, + label: Bm::z(0), + label2: None, + coeff: 0.1, + source: None, + }]; + + // Z₀ has no X component → no bit flips → α(S_Z) = 0 for all outcomes + // H correction should be zero for all outcomes + for outcome in &[vec![false, false], vec![true, true], vec![false, true], vec![true, false]] { + let p = outcome_probability(&gens, outcome, &stabs); + assert!(p.h_correction.abs() < 1e-10, + "H_Z should be invisible: outcome={outcome:?} h_corr={}", p.h_correction); + } +} + +/// Bell state: H_{X0} shifts probability between {00,11} and {01,10}. +#[test] +fn test_bell_h_x_shifts() { + let stabs = vec![ + Bm::x(0).multiply(&Bm::x(1)), // XX + Bm::z(0).multiply(&Bm::z(1)), // ZZ + ]; + let h = 0.05; + + let gens = vec![PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: h, + source: None, + }]; + + let p00 = outcome_probability(&gens, &[false, false], &stabs); + let p11 = outcome_probability(&gens, &[true, true], &stabs); + let p01 = outcome_probability(&gens, &[false, true], &stabs); + let p10 = outcome_probability(&gens, &[true, false], &stabs); + + eprintln!("Bell + H_X0: p00={:.6} p11={:.6} p01={:.6} p10={:.6}", + p00.total, p11.total, p01.total, p10.total); + + // X0 flips qubit 0: maps {00,11} ↔ {10,01} + // H_X creates probability at {01,10} from {00,11} + // p(01) and p(10) should be > 0 (increased from noiseless 0) + assert!(p01.h_correction > 0.0, "p(01) should increase"); + assert!(p10.h_correction > 0.0, "p(10) should increase"); + + // p(00) and p(11) should decrease + assert!(p00.h_correction < 0.0, "p(00) should decrease"); + assert!(p11.h_correction < 0.0, "p(11) should decrease"); + + // Conservation: total ≈ 1 + let sum = p00.total + p11.total + p01.total + p10.total; + assert!((sum - 1.0).abs() < 0.01, + "Conservation: sum={sum:.6}"); + + // Symmetry: p(01) = p(10) (X0 on symmetric Bell state) + assert!((p01.total - p10.total).abs() < 1e-10, + "Symmetry: p01={:.6} p10={:.6}", p01.total, p10.total); +} + +/// Multiple H generators: verify the off-diagonal Φ correctly accounts +/// for cross-generator interference. +#[test] +fn test_two_h_generators_interference() { + // |0⟩ with H_X rate h1 and H_Y rate h2 + let stabs = vec![Bm::z(0)]; + let h1 = 0.05; + let h2 = 0.03; + + let gens = vec![ + PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: h1, source: None }, + PropagatedEeg { eeg_type: EegType::H, label: Bm::y(0), label2: None, coeff: h2, source: None }, + ]; + + let p0 = outcome_probability(&gens, &[false], &stabs); + let p1 = outcome_probability(&gens, &[true], &stabs); + + // Diagonal: h1² + h2² for p(1) + let diagonal = h1 * h1 + h2 * h2; + + // X and Y both flip (both have X component set). + // Diagonal H·H: both contribute +h² to p(1). + // Off-diagonal: X·Y = iZ (anticommuting), so C_{X,Y} has α contribution + // from the off-diagonal Φ computation. + eprintln!("Two H gens: p0={:.6} p1={:.6} diagonal={diagonal:.6}", p0.total, p1.total); + + // p(1) should be at least the diagonal + assert!(p1.total >= diagonal * 0.9, + "p(1)={:.6} should be ≥ diagonal {diagonal:.6}", p1.total); + + // Conservation + assert!((p0.total + p1.total - 1.0).abs() < 0.01); +} + +/// C-type first-order α: directly construct a C generator and verify. +#[test] +fn test_c_type_alpha() { + // |0⟩ with C_{X,X} = 2S_X. Should give same result as S_X at double rate. + let stabs = vec![Bm::z(0)]; + let c = 0.005; + + let gens = vec![PropagatedEeg { + eeg_type: EegType::C, + label: Bm::x(0), + label2: Some(Bm::x(0)), + coeff: c, + source: None, + }]; + + let p0 = outcome_probability(&gens, &[false], &stabs); + let p1 = outcome_probability(&gens, &[true], &stabs); + + // C_{X,X} = 2S_X. α(C_{X,X}) at outcome 0: + // Φ(X,X) at 0 = 0 (flipped not in support), Φ(I,I) = 1. + // Φ(XX,I) = Φ(I,I) = 1. + // α = 2*Re(0) - Re(1 + 1) = -2. + // Correction: c * α = 0.005 * (-2) = -0.01. + // But wait — with the scale factor for pure state (ζ=0): scale=1. + // So ca_correction = 1 * 0.005 * (-2) = -0.01. + // p(0) = 1 + (-0.01) = 0.99. + + eprintln!("C-type: p0={:.6} p1={:.6}", p0.total, p1.total); + assert!((p0.total - 0.99).abs() < 0.02, "p(0) ≈ 0.99: got {:.6}", p0.total); + assert!(p1.total > 0.0, "p(1) should be positive"); +} + +/// A-type α: construct an A generator. For stabilizer states, A-type +/// typically gives zero (requires iQ1Q2 to be stabilizer eigenvalue). +#[test] +fn test_a_type_alpha_zero_for_stabilizer() { + // |0⟩ with A_{X,Z}: iXZ = iY. Is iY|0⟩ = ±|0⟩? Y|0⟩ = i|1⟩, so iY|0⟩ = -|1⟩. + // Not an eigenstate → α(A) should be 0 for both outcomes. + let stabs = vec![Bm::z(0)]; + + let gens = vec![PropagatedEeg { + eeg_type: EegType::A, + label: Bm::x(0), + label2: Some(Bm::z(0)), + coeff: 0.01, + source: None, + }]; + + let p0 = outcome_probability(&gens, &[false], &stabs); + let p1 = outcome_probability(&gens, &[true], &stabs); + + // A-type uses Im(Φ). For |0⟩ (real stabilizer state), Φ values + // should be real, so Im = 0, giving zero A-type correction. + eprintln!("A-type: p0_corr={:.8} p1_corr={:.8}", p0.s_correction + p0.h_correction, p1.s_correction + p1.h_correction); + // The ca_correction is part of total but not separately exposed. + // Just check total is unchanged from noiseless. + assert!((p0.total - 1.0).abs() < 1e-6, "A on |0⟩ should not change p(0)"); + assert!(p1.total.abs() < 1e-6, "A on |0⟩ should not change p(1)"); +} diff --git a/exp/pecos-eeg/tests/surface_code.rs b/exp/pecos-eeg/tests/surface_code.rs new file mode 100644 index 000000000..3c96a0f37 --- /dev/null +++ b/exp/pecos-eeg/tests/surface_code.rs @@ -0,0 +1,167 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Integration test: EEG analysis on a repetition code circuit. + +use pecos_core::Gate; +use pecos_eeg::Bm; +use pecos_eeg::circuit::{analyze_expanded, NoiseModel}; +use pecos_eeg::dem_mapping::*; +use pecos_eeg::eeg::EegType; +use pecos_eeg::expand; +use pecos_quantum::TickCircuit; + +/// Build a 3-qubit repetition code with 2 syndrome rounds. +/// +/// Layout: data qubits 0,1,2; ancilla qubits 3,4 +/// Stabilizers: Z0Z1 (measured by ancilla 3), Z1Z2 (measured by ancilla 4) +fn build_repetition_code() -> (Vec, Vec, Vec) { + let mut tc = TickCircuit::new(); + + // Initialize all qubits + tc.tick().pz(&[0, 1, 2, 3, 4]); + + // Two syndrome extraction rounds + for _round in 0..2 { + tc.tick().pz(&[3, 4]); + tc.tick().cx(&[(0, 3), (1, 4)]); + tc.tick().cx(&[(1, 3), (2, 4)]); + tc.tick().mz(&[3, 4]); + } + + // Final data readout + tc.tick().mz(&[0, 1, 2]); + + let gates: Vec = tc.iter_gates().cloned().collect(); + + // Detector stabilizers: X on ancilla qubit (anticommutes with Z errors + // that propagate through CX from data qubits). + let detectors = vec![ + Detector { + id: 0, + stabilizer: Bm::x(3), + }, + Detector { + id: 1, + stabilizer: Bm::x(4), + }, + ]; + + let observables = vec![Observable { + id: 0, + pauli: Bm::x(0).multiply(&Bm::x(1)).multiply(&Bm::x(2)), + }]; + + (gates, detectors, observables) +} + +#[test] +fn test_repetition_code_no_noise() { + let (gates, _, _) = build_repetition_code(); + let expanded = expand::expand_circuit(&gates); + let noise = NoiseModel::coherent_only(0.0); + let result = analyze_expanded(&expanded.gates, &noise); + + assert!(result.generators.is_empty()); +} + +#[test] +fn test_repetition_code_coherent_noise() { + let (gates, detectors, observables) = build_repetition_code(); + let expanded = expand::expand_circuit(&gates); + let noise = NoiseModel::coherent_only(0.1); + let result = analyze_expanded(&expanded.gates, &noise); + + let h_count = result.generators.iter() + .filter(|g| g.eeg_type == EegType::H) + .count(); + assert!(h_count > 0, "Should have H generators from RZ noise"); + + let dem_entries = build_dem(&result.generators, &detectors, &observables); + + assert!( + !dem_entries.is_empty(), + "Coherent noise should produce detection events" + ); + + let dem_str = format_dem(&dem_entries); + eprintln!("Coherent DEM:\n{dem_str}"); + + for entry in &dem_entries { + assert!(entry.probability > 0.0, "Probability must be positive"); + assert!(entry.probability < 1.0, "Probability {:.6} too large", entry.probability); + } +} + +#[test] +fn test_repetition_code_depolarizing_noise() { + let (gates, detectors, observables) = build_repetition_code(); + let expanded = expand::expand_circuit(&gates); + let noise = NoiseModel::depolarizing(0.003); + let result = analyze_expanded(&expanded.gates, &noise); + + let s_count = result.generators.iter() + .filter(|g| g.eeg_type == EegType::S) + .count(); + assert!(s_count > 0); + + let dem_entries = build_dem(&result.generators, &detectors, &observables); + + let dem_str = format_dem(&dem_entries); + eprintln!("Stochastic DEM:\n{dem_str}"); + + assert!(!dem_entries.is_empty()); + for entry in &dem_entries { + assert!(entry.probability > 0.0); + assert!(entry.probability < 0.5); + } +} + +#[test] +fn test_repetition_code_combined_noise() { + let (gates, detectors, observables) = build_repetition_code(); + let expanded = expand::expand_circuit(&gates); + let noise = NoiseModel::depolarizing(0.003).with_idle_rz(0.1); + let result = analyze_expanded(&expanded.gates, &noise); + + let h_count = result.generators.iter() + .filter(|g| g.eeg_type == EegType::H).count(); + let s_count = result.generators.iter() + .filter(|g| g.eeg_type == EegType::S).count(); + assert!(h_count > 0); + assert!(s_count > 0); + + let dem_entries = build_dem(&result.generators, &detectors, &observables); + + let dem_str = format_dem(&dem_entries); + eprintln!("Combined DEM:\n{dem_str}"); + + assert!(!dem_entries.is_empty()); +} + +#[test] +fn test_eeg_generator_count_scales_linearly() { + for num_rounds in [1, 2, 4, 8] { + let mut tc = TickCircuit::new(); + tc.tick().pz(&[0, 1, 2, 3, 4]); + + for _ in 0..num_rounds { + tc.tick().pz(&[3, 4]); + tc.tick().cx(&[(0, 3), (1, 4)]); + tc.tick().cx(&[(1, 3), (2, 4)]); + tc.tick().mz(&[3, 4]); + } + tc.tick().mz(&[0, 1, 2]); + + let gates: Vec = tc.iter_gates().cloned().collect(); + let expanded = expand::expand_circuit(&gates); + let noise = NoiseModel::coherent_only(0.1); + let result = analyze_expanded(&expanded.gates, &noise); + + let h_count = result.generators.iter() + .filter(|g| g.eeg_type == EegType::H).count(); + eprintln!("Rounds={num_rounds}: {h_count} H generators"); + assert!(h_count < 1000, "Generator count should be polynomial"); + } +} diff --git a/exp/pecos-experimental/src/hugr_executor.rs b/exp/pecos-experimental/src/hugr_executor.rs index b5a792faf..b4c15ae04 100644 --- a/exp/pecos-experimental/src/hugr_executor.rs +++ b/exp/pecos-experimental/src/hugr_executor.rs @@ -213,7 +213,8 @@ where | GateType::QFree | GateType::Idle | GateType::MeasCrosstalkGlobalPayload - | GateType::MeasCrosstalkLocalPayload => {} + | GateType::MeasCrosstalkLocalPayload + | GateType::PauliOperatorMeta => {} // Single-qubit Clifford gates GateType::X => { diff --git a/exp/pecos-experimental/src/noisy_symbolic.rs b/exp/pecos-experimental/src/noisy_symbolic.rs index 13334ed8a..a0a20a356 100644 --- a/exp/pecos-experimental/src/noisy_symbolic.rs +++ b/exp/pecos-experimental/src/noisy_symbolic.rs @@ -233,9 +233,9 @@ impl NoisyMeasurementKind { random_deps, fault_deps, flip, - } => { + } // Check if this is effectively a copy/flipped-copy - if fault_deps.is_empty() && random_deps.len() == 1 { + if fault_deps.is_empty() && random_deps.len() == 1 => { let r_idx = random_deps[0]; if let Some(&src_meas) = random_column_sources.get(&r_idx) { if *flip { @@ -245,7 +245,6 @@ impl NoisyMeasurementKind { } } } - } _ => {} } } @@ -699,145 +698,130 @@ impl NoisyMeasurementHistoryBuilder { | GateType::Z | GateType::H | GateType::SZ - | GateType::SZdg => { - if self.noise_model.p1 > 0.0 { - let q = location.qubits[0]; - let p_each = self.noise_model.p1 / 3.0; + | GateType::SZdg + if self.noise_model.p1 > 0.0 => + { + let q = location.qubits[0]; + let p_each = self.noise_model.p1 / 3.0; - for pauli in [Pauli::X, Pauli::Y, Pauli::Z] { - let affected = Self::propagate_fault( - pauli, - q, - loc_idx + 1, // Fault occurs AFTER the gate - all_gates, - measurement_positions, - ); + for pauli in [Pauli::X, Pauli::Y, Pauli::Z] { + let affected = Self::propagate_fault( + pauli, + q, + loc_idx + 1, // Fault occurs AFTER the gate + all_gates, + measurement_positions, + ); - if !affected.is_empty() { - history.add_fault( - p_each, - &affected, - format!("{pauli} after {:?} on q{q}", location.gate_type), - ); - } + if !affected.is_empty() { + history.add_fault( + p_each, + &affected, + format!("{pauli} after {:?} on q{q}", location.gate_type), + ); } } } // Two-qubit Clifford gates: depolarizing noise applies one of 15 Pauli pairs - GateType::CX | GateType::CY | GateType::CZ => { - if self.noise_model.p2 > 0.0 { - let q1 = location.qubits[0]; - let q2 = location.qubits[1]; - let p_each = self.noise_model.p2 / 15.0; - - // All 15 non-identity Pauli pairs - let paulis = [Pauli::X, Pauli::Y, Pauli::Z]; - for &p1 in &paulis { - for &p2 in &paulis { - // Both qubits get a Pauli (IX, IY, IZ already covered, skip II) - let affected = Self::propagate_two_qubit_fault( - p1, - q1, - p2, - q2, - loc_idx + 1, - all_gates, - measurement_positions, - ); - - if !affected.is_empty() { - history.add_fault( - p_each, - &affected, - format!( - "{p1}{p2} after {:?} on q{q1},q{q2}", - location.gate_type - ), - ); - } - } - } - - // Also handle single-qubit Paulis on each qubit (XI, YI, ZI, IX, IY, IZ) - // These are the remaining 6 of the 15 non-identity pairs - for &p in &paulis { - // Pauli on q1 only - let affected = Self::propagate_fault( - p, + GateType::CX | GateType::CY | GateType::CZ if self.noise_model.p2 > 0.0 => { + let q1 = location.qubits[0]; + let q2 = location.qubits[1]; + let p_each = self.noise_model.p2 / 15.0; + + // All 15 non-identity Pauli pairs + let paulis = [Pauli::X, Pauli::Y, Pauli::Z]; + for &p1 in &paulis { + for &p2 in &paulis { + // Both qubits get a Pauli (IX, IY, IZ already covered, skip II) + let affected = Self::propagate_two_qubit_fault( + p1, q1, - loc_idx + 1, - all_gates, - measurement_positions, - ); - if !affected.is_empty() { - history.add_fault( - p_each, - &affected, - format!("{p}I after {:?} on q{q1},q{q2}", location.gate_type), - ); - } - - // Pauli on q2 only - let affected = Self::propagate_fault( - p, + p2, q2, loc_idx + 1, all_gates, measurement_positions, ); + if !affected.is_empty() { history.add_fault( p_each, &affected, - format!("I{p} after {:?} on q{q1},q{q2}", location.gate_type), + format!("{p1}{p2} after {:?} on q{q1},q{q2}", location.gate_type), ); } } } - } - - // State preparation: X error with probability p_prep - GateType::PZ | GateType::QAlloc => { - if self.noise_model.p_prep > 0.0 && !location.qubits.is_empty() { - let q = location.qubits[0]; - - // X error flips the prepared |0⟩ to |1⟩ - let affected = Self::propagate_fault( - Pauli::X, - q, - loc_idx + 1, - all_gates, - measurement_positions, - ); + // Also handle single-qubit Paulis on each qubit (XI, YI, ZI, IX, IY, IZ) + // These are the remaining 6 of the 15 non-identity pairs + for &p in &paulis { + // Pauli on q1 only + let affected = + Self::propagate_fault(p, q1, loc_idx + 1, all_gates, measurement_positions); if !affected.is_empty() { history.add_fault( - self.noise_model.p_prep, + p_each, &affected, - format!("X prep error on q{q}"), + format!("{p}I after {:?} on q{q1},q{q2}", location.gate_type), ); } - } - } - - // Measurement: flip the measurement outcome with probability p_meas - GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked => { - if self.noise_model.p_meas > 0.0 { - // Measurement fault directly flips this measurement - if let Some(&meas_idx) = measurement_positions.get(&loc_idx) { - let mut affected = BTreeSet::new(); - affected.insert(meas_idx); + // Pauli on q2 only + let affected = + Self::propagate_fault(p, q2, loc_idx + 1, all_gates, measurement_positions); + if !affected.is_empty() { history.add_fault( - self.noise_model.p_meas, + p_each, &affected, - format!("Meas fault on m{meas_idx}"), + format!("I{p} after {:?} on q{q1},q{q2}", location.gate_type), ); } } } + // State preparation: X error with probability p_prep + GateType::PZ | GateType::QAlloc + if self.noise_model.p_prep > 0.0 && !location.qubits.is_empty() => + { + let q = location.qubits[0]; + + // X error flips the prepared |0⟩ to |1⟩ + let affected = Self::propagate_fault( + Pauli::X, + q, + loc_idx + 1, + all_gates, + measurement_positions, + ); + + if !affected.is_empty() { + history.add_fault( + self.noise_model.p_prep, + &affected, + format!("X prep error on q{q}"), + ); + } + } + + // Measurement: flip the measurement outcome with probability p_meas + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked + if self.noise_model.p_meas > 0.0 => + { + // Measurement fault directly flips this measurement + if let Some(&meas_idx) = measurement_positions.get(&loc_idx) { + let mut affected = BTreeSet::new(); + affected.insert(meas_idx); + + history.add_fault( + self.noise_model.p_meas, + &affected, + format!("Meas fault on m{meas_idx}"), + ); + } + } + // Other gates: no noise applied _ => {} } @@ -870,56 +854,44 @@ impl NoisyMeasurementHistoryBuilder { // Single-qubit Clifford gates // Note: X, Y, Z gates don't change the X/Z basis of Paulis for propagation purposes // (sign changes don't affect measurement flips), so they fall through to _ => {} - GateType::H => { - if !location.qubits.is_empty() { - prop.h(&[QubitId(location.qubits[0])]); - } + GateType::H if !location.qubits.is_empty() => { + prop.h(&[QubitId(location.qubits[0])]); } - GateType::SZ => { - if !location.qubits.is_empty() { - prop.sz(&[QubitId(location.qubits[0])]); - } + GateType::SZ if !location.qubits.is_empty() => { + prop.sz(&[QubitId(location.qubits[0])]); } - GateType::SZdg => { - if !location.qubits.is_empty() { - // S† = S³ - let q = QubitId(location.qubits[0]); - prop.sz(&[q]).sz(&[q]).sz(&[q]); - } + GateType::SZdg if !location.qubits.is_empty() => { + // S† = S³ + let q = QubitId(location.qubits[0]); + prop.sz(&[q]).sz(&[q]).sz(&[q]); } // Two-qubit Clifford gates - GateType::CX => { - if location.qubits.len() >= 2 { - prop.cx(&[(QubitId(location.qubits[0]), QubitId(location.qubits[1]))]); - } + GateType::CX if location.qubits.len() >= 2 => { + prop.cx(&[(QubitId(location.qubits[0]), QubitId(location.qubits[1]))]); } - GateType::CY => { - if location.qubits.len() >= 2 { - let (q1, q2) = (QubitId(location.qubits[0]), QubitId(location.qubits[1])); - // CY = (I ⊗ S†) CX (I ⊗ S) - prop.sz(&[q2]).cx(&[(q1, q2)]).sz(&[q2]).sz(&[q2]).sz(&[q2]); - } + GateType::CY if location.qubits.len() >= 2 => { + let (q1, q2) = (QubitId(location.qubits[0]), QubitId(location.qubits[1])); + // CY = (I ⊗ S†) CX (I ⊗ S) + prop.sz(&[q2]).cx(&[(q1, q2)]).sz(&[q2]).sz(&[q2]).sz(&[q2]); } - GateType::CZ => { - if location.qubits.len() >= 2 { - let (q1, q2) = (QubitId(location.qubits[0]), QubitId(location.qubits[1])); - // CZ = (I ⊗ H) CX (I ⊗ H) - prop.h(&[q2]).cx(&[(q1, q2)]).h(&[q2]); - } + GateType::CZ if location.qubits.len() >= 2 => { + let (q1, q2) = (QubitId(location.qubits[0]), QubitId(location.qubits[1])); + // CZ = (I ⊗ H) CX (I ⊗ H) + prop.h(&[q2]).cx(&[(q1, q2)]).h(&[q2]); } // Measurements - GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked => { - if !location.qubits.is_empty() { - let q = location.qubits[0]; - // Check if this fault would flip the measurement - // A Z-basis measurement is flipped iff there's an X component - if prop.contains_x(q) - && let Some(&meas_idx) = measurement_positions.get(&loc_idx) - { - affected_measurements.insert(meas_idx); - } + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked + if !location.qubits.is_empty() => + { + let q = location.qubits[0]; + // Check if this fault would flip the measurement + // A Z-basis measurement is flipped iff there's an X component + if prop.contains_x(q) + && let Some(&meas_idx) = measurement_positions.get(&loc_idx) + { + affected_measurements.insert(meas_idx); } } @@ -960,47 +932,35 @@ impl NoisyMeasurementHistoryBuilder { // Propagate through subsequent gates (same logic as single-qubit) for (loc_idx, location) in all_gates.iter().enumerate().skip(start_loc) { match location.gate_type { - GateType::H => { - if !location.qubits.is_empty() { - prop.h(&[QubitId(location.qubits[0])]); - } + GateType::H if !location.qubits.is_empty() => { + prop.h(&[QubitId(location.qubits[0])]); } - GateType::SZ => { - if !location.qubits.is_empty() { - prop.sz(&[QubitId(location.qubits[0])]); - } + GateType::SZ if !location.qubits.is_empty() => { + prop.sz(&[QubitId(location.qubits[0])]); } - GateType::SZdg => { - if !location.qubits.is_empty() { - let q = QubitId(location.qubits[0]); - prop.sz(&[q]).sz(&[q]).sz(&[q]); - } + GateType::SZdg if !location.qubits.is_empty() => { + let q = QubitId(location.qubits[0]); + prop.sz(&[q]).sz(&[q]).sz(&[q]); } - GateType::CX => { - if location.qubits.len() >= 2 { - prop.cx(&[(QubitId(location.qubits[0]), QubitId(location.qubits[1]))]); - } + GateType::CX if location.qubits.len() >= 2 => { + prop.cx(&[(QubitId(location.qubits[0]), QubitId(location.qubits[1]))]); } - GateType::CY => { - if location.qubits.len() >= 2 { - let (q1, q2) = (QubitId(location.qubits[0]), QubitId(location.qubits[1])); - prop.sz(&[q2]).cx(&[(q1, q2)]).sz(&[q2]).sz(&[q2]).sz(&[q2]); - } + GateType::CY if location.qubits.len() >= 2 => { + let (q1, q2) = (QubitId(location.qubits[0]), QubitId(location.qubits[1])); + prop.sz(&[q2]).cx(&[(q1, q2)]).sz(&[q2]).sz(&[q2]).sz(&[q2]); } - GateType::CZ => { - if location.qubits.len() >= 2 { - let (q1, q2) = (QubitId(location.qubits[0]), QubitId(location.qubits[1])); - prop.h(&[q2]).cx(&[(q1, q2)]).h(&[q2]); - } + GateType::CZ if location.qubits.len() >= 2 => { + let (q1, q2) = (QubitId(location.qubits[0]), QubitId(location.qubits[1])); + prop.h(&[q2]).cx(&[(q1, q2)]).h(&[q2]); } - GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked => { - if !location.qubits.is_empty() { - let q = location.qubits[0]; - if prop.contains_x(q) - && let Some(&meas_idx) = measurement_positions.get(&loc_idx) - { - affected_measurements.insert(meas_idx); - } + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked + if !location.qubits.is_empty() => + { + let q = location.qubits[0]; + if prop.contains_x(q) + && let Some(&meas_idx) = measurement_positions.get(&loc_idx) + { + affected_measurements.insert(meas_idx); } } _ => {} diff --git a/exp/pecos-neo/Cargo.toml b/exp/pecos-neo/Cargo.toml index 115fa6e10..69786fbac 100644 --- a/exp/pecos-neo/Cargo.toml +++ b/exp/pecos-neo/Cargo.toml @@ -28,6 +28,7 @@ num_cpus = "1.16" # Optional: for adapter to wrap classical engines pecos-engines = { workspace = true, optional = true } + # Optional: for program types (Qasm, Program enum, etc.) pecos-programs = { workspace = true, optional = true } # Optional: for QASM support @@ -37,6 +38,7 @@ pecos-hugr = { workspace = true, optional = true } [dev-dependencies] rand.workspace = true +num-complex.workspace = true pecos-engines.workspace = true pecos-qasm.workspace = true pecos-hugr.workspace = true diff --git a/exp/pecos-neo/benches/hot_path.rs b/exp/pecos-neo/benches/hot_path.rs index 64fe99bcc..f11053cbd 100644 --- a/exp/pecos-neo/benches/hot_path.rs +++ b/exp/pecos-neo/benches/hot_path.rs @@ -1206,8 +1206,8 @@ fn bench_batch_processor(c: &mut Criterion) { let mut state = BatchState::new(num_qubits); state.mark_all_active(); // Mark leaked_pct% as leaked - let step = if leaked_pct > 0 { - 100 / leaked_pct + let step = if let Some(s) = 100usize.checked_div(leaked_pct) { + s } else { num_qubits + 1 }; diff --git a/exp/pecos-neo/docs/design/extensible-gates-test-plan.md b/exp/pecos-neo/docs/design/extensible-gates-test-plan.md index 3644715d1..de8a5aca8 100644 --- a/exp/pecos-neo/docs/design/extensible-gates-test-plan.md +++ b/exp/pecos-neo/docs/design/extensible-gates-test-plan.md @@ -738,7 +738,7 @@ fn test_program_serialization_roundtrip() { ```rust #[test] fn test_standard_adaptor_decomposes_t() { - let adaptor = StandardAdaptor::clifford_rz(); + let adaptor = StandardAdaptor::stab_vec(); assert!(adaptor.can_adapt(gates::T)); @@ -752,7 +752,7 @@ fn test_standard_adaptor_decomposes_t() { #[test] fn test_standard_adaptor_decomposes_swap() { - let adaptor = StandardAdaptor::clifford_rz(); + let adaptor = StandardAdaptor::stab_vec(); let decomposed = adaptor.adapt(gates::SWAP, &[QubitId(0), QubitId(1)], &[], &[]); @@ -763,7 +763,7 @@ fn test_standard_adaptor_decomposes_swap() { #[test] fn test_adaptor_bitset_lookup() { - let adaptor = StandardAdaptor::clifford_rz(); + let adaptor = StandardAdaptor::stab_vec(); // Fast bit test assert!(adaptor.can_adapt(gates::T)); diff --git a/exp/pecos-neo/docs/design/extensible-gates.md b/exp/pecos-neo/docs/design/extensible-gates.md index 4524b6d2b..f2f42daf8 100644 --- a/exp/pecos-neo/docs/design/extensible-gates.md +++ b/exp/pecos-neo/docs/design/extensible-gates.md @@ -914,7 +914,7 @@ pub struct StandardAdaptor { impl StandardAdaptor { /// Create adaptor targeting Clifford+RZ gate set - pub fn clifford_rz() -> Self { + pub fn stab_vec() -> Self { let mut bits = BitVec::repeat(false, 256); // Mark gates we can decompose bits.set(gates::RX.0 as usize, true); diff --git a/exp/pecos-neo/src/adapter.rs b/exp/pecos-neo/src/adapter.rs index 1d9c2f9d2..8f01c29f7 100644 --- a/exp/pecos-neo/src/adapter.rs +++ b/exp/pecos-neo/src/adapter.rs @@ -85,6 +85,8 @@ fn convert_gate_type(core_type: CoreGateType) -> Option { // Single-qubit Cliffords CoreGateType::H => NeoGateType::H, + CoreGateType::F => NeoGateType::F, + CoreGateType::Fdg => NeoGateType::Fdg, CoreGateType::SX => NeoGateType::SX, CoreGateType::SXdg => NeoGateType::SXdg, CoreGateType::SY => NeoGateType::SY, @@ -107,6 +109,10 @@ fn convert_gate_type(core_type: CoreGateType) -> Option { CoreGateType::CZ => NeoGateType::CZ, CoreGateType::SZZ => NeoGateType::SZZ, CoreGateType::SZZdg => NeoGateType::SZZdg, + CoreGateType::SXX => NeoGateType::SXX, + CoreGateType::SXXdg => NeoGateType::SXXdg, + CoreGateType::SYY => NeoGateType::SYY, + CoreGateType::SYYdg => NeoGateType::SYYdg, CoreGateType::SWAP => NeoGateType::SWAP, CoreGateType::CRZ => NeoGateType::CRZ, CoreGateType::RXX => NeoGateType::RXX, @@ -398,6 +404,8 @@ fn convert_neo_to_core_gate_type(neo_type: NeoGateType) -> CoreGateType { NeoGateType::Y => CoreGateType::Y, NeoGateType::Z => CoreGateType::Z, NeoGateType::H => CoreGateType::H, + NeoGateType::F => CoreGateType::F, + NeoGateType::Fdg => CoreGateType::Fdg, NeoGateType::SX => CoreGateType::SX, NeoGateType::SXdg => CoreGateType::SXdg, NeoGateType::SY => CoreGateType::SY, @@ -416,6 +424,10 @@ fn convert_neo_to_core_gate_type(neo_type: NeoGateType) -> CoreGateType { NeoGateType::CZ => CoreGateType::CZ, NeoGateType::SZZ => CoreGateType::SZZ, NeoGateType::SZZdg => CoreGateType::SZZdg, + NeoGateType::SXX => CoreGateType::SXX, + NeoGateType::SXXdg => CoreGateType::SXXdg, + NeoGateType::SYY => CoreGateType::SYY, + NeoGateType::SYYdg => CoreGateType::SYYdg, NeoGateType::SWAP => CoreGateType::SWAP, NeoGateType::CRZ => CoreGateType::CRZ, NeoGateType::RXX => CoreGateType::RXX, diff --git a/exp/pecos-neo/src/circuit.rs b/exp/pecos-neo/src/circuit.rs index a445bd23e..c4d802adc 100644 --- a/exp/pecos-neo/src/circuit.rs +++ b/exp/pecos-neo/src/circuit.rs @@ -55,6 +55,8 @@ impl From for GateType { CoreGT::Y => Self::Y, CoreGT::Z => Self::Z, CoreGT::H => Self::H, + CoreGT::F => Self::F, + CoreGT::Fdg => Self::Fdg, CoreGT::SX => Self::SX, CoreGT::SXdg => Self::SXdg, CoreGT::SY => Self::SY, @@ -101,6 +103,8 @@ impl From for pecos_core::gate_type::GateType { GateType::Y => CoreGT::Y, GateType::Z => CoreGT::Z, GateType::H => CoreGT::H, + GateType::F => CoreGT::F, + GateType::Fdg => CoreGT::Fdg, GateType::SX => CoreGT::SX, GateType::SXdg => CoreGT::SXdg, GateType::SY => CoreGT::SY, @@ -119,6 +123,10 @@ impl From for pecos_core::gate_type::GateType { GateType::CZ => CoreGT::CZ, GateType::SZZ => CoreGT::SZZ, GateType::SZZdg => CoreGT::SZZdg, + GateType::SXX => CoreGT::SXX, + GateType::SXXdg => CoreGT::SXXdg, + GateType::SYY => CoreGT::SYY, + GateType::SYYdg => CoreGT::SYYdg, GateType::SWAP => CoreGT::SWAP, GateType::CRZ => CoreGT::CRZ, GateType::RXX => CoreGT::RXX, @@ -288,6 +296,7 @@ impl From<&CommandQueue> for TickCircuit { angles, params: SmallVec::new(), qubits: qubit_ids, + meas_ids: SmallVec::new(), }; // Use try_add_gate and ignore errors (shouldn't happen with one gate per tick) let _ = tick.try_add_gate(gate); @@ -419,6 +428,7 @@ mod tests { angles: smallvec::smallvec![Angle64::QUARTER_TURN], params: SmallVec::new(), qubits: smallvec::smallvec![QubitId(0)], + meas_ids: SmallVec::new(), }; let cmd: GateCommand = (&gate).into(); diff --git a/exp/pecos-neo/src/command.rs b/exp/pecos-neo/src/command.rs index b42bae781..a26c8b3a4 100644 --- a/exp/pecos-neo/src/command.rs +++ b/exp/pecos-neo/src/command.rs @@ -37,6 +37,8 @@ pub enum GateType { // Single-qubit Cliffords H, + F, + Fdg, SX, SXdg, SY, @@ -59,6 +61,10 @@ pub enum GateType { CZ, SZZ, SZZdg, + SXX, + SXXdg, + SYY, + SYYdg, SWAP, CRZ, RXX, @@ -90,6 +96,8 @@ impl GateType { | Self::Y | Self::Z | Self::H + | Self::F + | Self::Fdg | Self::SX | Self::SXdg | Self::SY @@ -116,6 +124,10 @@ impl GateType { | Self::CZ | Self::SZZ | Self::SZZdg + | Self::SXX + | Self::SXXdg + | Self::SYY + | Self::SYYdg | Self::SWAP | Self::CRZ | Self::RXX @@ -160,6 +172,31 @@ impl GateType { pub const fn is_preparation(self) -> bool { matches!(self, Self::PZ | Self::QAlloc) } + + /// Returns true if this is an idle operation. + #[must_use] + pub const fn is_idle(self) -> bool { + matches!(self, Self::Idle) + } + + /// Returns true if this is a resource management operation. + #[must_use] + pub const fn is_resource_management(self) -> bool { + matches!(self, Self::QAlloc | Self::QFree) + } + + /// Returns true if this is a unitary gate (not preparation, measurement, + /// idle, or resource management). + /// + /// These are the gates that should receive gate depolarizing noise + /// (p1 for single-qubit, p2 for two-qubit). + #[must_use] + pub const fn is_unitary_gate(self) -> bool { + !self.is_measurement() + && !self.is_preparation() + && !self.is_idle() + && !self.is_resource_management() + } } /// A single quantum gate command. diff --git a/exp/pecos-neo/src/command/builder.rs b/exp/pecos-neo/src/command/builder.rs index 4a4ece180..65b673d87 100644 --- a/exp/pecos-neo/src/command/builder.rs +++ b/exp/pecos-neo/src/command/builder.rs @@ -136,6 +136,28 @@ impl CommandBuilder { self } + /// Add face gates. + #[must_use] + pub fn f(mut self, qubits: &[impl Into + Copy]) -> Self { + for &q in qubits { + self.queue + .push(GateCommand::new(GateType::F, smallvec::smallvec![q.into()])); + } + self + } + + /// Add face-dagger gates. + #[must_use] + pub fn fdg(mut self, qubits: &[impl Into + Copy]) -> Self { + for &q in qubits { + self.queue.push(GateCommand::new( + GateType::Fdg, + smallvec::smallvec![q.into()], + )); + } + self + } + /// Add SX (sqrt-X) gates. #[must_use] pub fn sx(mut self, qubits: &[impl Into + Copy]) -> Self { @@ -276,6 +298,24 @@ impl CommandBuilder { self } + /// Add R1XY rotation gates with two angles (theta, phi). + #[must_use] + pub fn r1xy( + mut self, + qubits: &[impl Into + Copy], + theta: impl Into + Copy, + phi: impl Into + Copy, + ) -> Self { + for &q in qubits { + self.queue.push(GateCommand::with_angles( + GateType::R1XY, + smallvec::smallvec![q.into()], + smallvec::smallvec![theta.into(), phi.into()], + )); + } + self + } + // Two-qubit gates /// Add CNOT (CX) gates. @@ -321,6 +361,75 @@ impl CommandBuilder { self } + /// Add SXX gates. + #[must_use] + pub fn sxx(mut self, pairs: &[(impl Into + Copy, impl Into + Copy)]) -> Self { + for &(q0, q1) in pairs { + self.queue.push(GateCommand::new( + GateType::SXX, + smallvec::smallvec![q0.into(), q1.into()], + )); + } + self + } + + /// Add SXXdg gates. + #[must_use] + pub fn sxxdg( + mut self, + pairs: &[(impl Into + Copy, impl Into + Copy)], + ) -> Self { + for &(q0, q1) in pairs { + self.queue.push(GateCommand::new( + GateType::SXXdg, + smallvec::smallvec![q0.into(), q1.into()], + )); + } + self + } + + /// Add SYY gates. + #[must_use] + pub fn syy(mut self, pairs: &[(impl Into + Copy, impl Into + Copy)]) -> Self { + for &(q0, q1) in pairs { + self.queue.push(GateCommand::new( + GateType::SYY, + smallvec::smallvec![q0.into(), q1.into()], + )); + } + self + } + + /// Add SYYdg gates. + #[must_use] + pub fn syydg( + mut self, + pairs: &[(impl Into + Copy, impl Into + Copy)], + ) -> Self { + for &(q0, q1) in pairs { + self.queue.push(GateCommand::new( + GateType::SYYdg, + smallvec::smallvec![q0.into(), q1.into()], + )); + } + self + } + + /// Add SZZdg gates (inverse of SZZ). + #[must_use] + pub fn szzdg( + mut self, + pairs: &[(impl Into + Copy, impl Into + Copy)], + ) -> Self { + for &(q0, q1) in pairs { + self.queue.push(GateCommand::new( + GateType::SZZdg, + smallvec::smallvec![q0.into(), q1.into()], + )); + } + self + } + /// Add SWAP gates. #[must_use] pub fn swap( diff --git a/exp/pecos-neo/src/command/signal_store.rs b/exp/pecos-neo/src/command/signal_store.rs index 05d3024ec..eae246cfa 100644 --- a/exp/pecos-neo/src/command/signal_store.rs +++ b/exp/pecos-neo/src/command/signal_store.rs @@ -92,7 +92,7 @@ impl SignalVec for TypedSignalVec { } fn fmt_debug(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - write!(f, "{}[{}]", S::name(), self.positions.len(),) + write!(f, "{}[{}]", S::name(), self.positions.len()) } fn positions(&self) -> &[u32] { diff --git a/exp/pecos-neo/src/extensible/adaptor.rs b/exp/pecos-neo/src/extensible/adaptor.rs index 42f02735a..150d48bd8 100644 --- a/exp/pecos-neo/src/extensible/adaptor.rs +++ b/exp/pecos-neo/src/extensible/adaptor.rs @@ -73,14 +73,14 @@ pub struct StandardAdaptor { impl Default for StandardAdaptor { fn default() -> Self { - Self::clifford_rz() + Self::stab_vec() } } impl StandardAdaptor { /// Create an adaptor targeting Clifford+RZ gate set. #[must_use] - pub fn clifford_rz() -> Self { + pub fn stab_vec() -> Self { let mut bits = GateSupportSet::new(); // Gates we can decompose into Clifford+RZ @@ -469,7 +469,7 @@ impl CompositeExtendedAdaptor { use super::stabilizer_adaptor::StabilizerAdaptor; Self::new() - .with_gate_adaptor(StandardAdaptor::clifford_rz()) + .with_gate_adaptor(StandardAdaptor::stab_vec()) .with(StabilizerAdaptor::new()) } } @@ -538,7 +538,7 @@ mod extended_tests { #[test] fn test_lifted_adaptor() { - let standard = StandardAdaptor::clifford_rz(); + let standard = StandardAdaptor::stab_vec(); let lifted = LiftedAdaptor::new(standard); assert!(lifted.can_adapt(gates::T)); @@ -583,7 +583,7 @@ mod extended_tests { #[test] fn test_swap_decomposition_via_lifted() { - let lifted = LiftedAdaptor::new(StandardAdaptor::clifford_rz()); + let lifted = LiftedAdaptor::new(StandardAdaptor::stab_vec()); let seq = lifted.adapt(gates::SWAP, &[QubitId(0), QubitId(1)], &[], &[]); diff --git a/exp/pecos-neo/src/extensible/bridge.rs b/exp/pecos-neo/src/extensible/bridge.rs index 0e9549674..ca367a006 100644 --- a/exp/pecos-neo/src/extensible/bridge.rs +++ b/exp/pecos-neo/src/extensible/bridge.rs @@ -21,6 +21,8 @@ impl GateType { // Single-qubit Cliffords Self::H => gates::H, + Self::F => gates::F, + Self::Fdg => gates::Fdg, Self::SX => gates::SX, Self::SXdg => gates::SXdg, Self::SY => gates::SY, @@ -43,6 +45,10 @@ impl GateType { Self::CZ => gates::CZ, Self::SZZ => gates::SZZ, Self::SZZdg => gates::SZZdg, + Self::SXX => gates::SXX, + Self::SXXdg => gates::SXXdg, + Self::SYY => gates::SYY, + Self::SYYdg => gates::SYYdg, Self::SWAP => gates::SWAP, Self::CRZ => gates::CRZ, Self::RXX => gates::RXX, @@ -94,6 +100,8 @@ impl GateId { 14 => GateType::SYdg, 15 => GateType::SZ, 16 => GateType::SZdg, + 17 => GateType::F, + 18 => GateType::Fdg, // T gates 20 => GateType::T, @@ -113,6 +121,10 @@ impl GateId { 53 => GateType::SWAP, // Two-qubit Clifford rotations + 60 => GateType::SXX, + 61 => GateType::SXXdg, + 62 => GateType::SYY, + 63 => GateType::SYYdg, 64 => GateType::SZZ, 65 => GateType::SZZdg, @@ -202,6 +214,8 @@ mod tests { GateType::Y, GateType::Z, GateType::H, + GateType::F, + GateType::Fdg, GateType::SX, GateType::SXdg, GateType::SY, @@ -220,6 +234,10 @@ mod tests { GateType::CZ, GateType::SZZ, GateType::SZZdg, + GateType::SXX, + GateType::SXXdg, + GateType::SYY, + GateType::SYYdg, GateType::SWAP, GateType::CRZ, GateType::RXX, @@ -286,6 +304,8 @@ mod tests { assert_eq!(GateType::I.to_gate_id(), gates::I); assert_eq!(GateType::X.to_gate_id(), gates::X); assert_eq!(GateType::H.to_gate_id(), gates::H); + assert_eq!(GateType::F.to_gate_id(), gates::F); + assert_eq!(GateType::Fdg.to_gate_id(), gates::Fdg); assert_eq!(GateType::RZ.to_gate_id(), gates::RZ); assert_eq!(GateType::CX.to_gate_id(), gates::CX); assert_eq!(GateType::CCX.to_gate_id(), gates::CCX); diff --git a/exp/pecos-neo/src/extensible/definitions.rs b/exp/pecos-neo/src/extensible/definitions.rs index c1ed5cd6d..ef36b882b 100644 --- a/exp/pecos-neo/src/extensible/definitions.rs +++ b/exp/pecos-neo/src/extensible/definitions.rs @@ -325,6 +325,14 @@ impl GateDefinitions { gates::H, GateSpec::new("H").with_category(GateCategory::SingleQubitUnitary), ); + self.set_core_spec( + gates::F, + GateSpec::new("F").with_category(GateCategory::SingleQubitUnitary), + ); + self.set_core_spec( + gates::Fdg, + GateSpec::new("Fdg").with_category(GateCategory::SingleQubitUnitary), + ); self.set_core_spec( gates::SX, GateSpec::new("SX").with_category(GateCategory::SingleQubitUnitary), @@ -417,6 +425,42 @@ impl GateDefinitions { .with_quantum_arity(2) .with_category(GateCategory::TwoQubitUnitary), ); + self.set_core_spec( + gates::SXX, + GateSpec::new("SXX") + .with_quantum_arity(2) + .with_category(GateCategory::TwoQubitUnitary), + ); + self.set_core_spec( + gates::SXXdg, + GateSpec::new("SXXdg") + .with_quantum_arity(2) + .with_category(GateCategory::TwoQubitUnitary), + ); + self.set_core_spec( + gates::SYY, + GateSpec::new("SYY") + .with_quantum_arity(2) + .with_category(GateCategory::TwoQubitUnitary), + ); + self.set_core_spec( + gates::SYYdg, + GateSpec::new("SYYdg") + .with_quantum_arity(2) + .with_category(GateCategory::TwoQubitUnitary), + ); + self.set_core_spec( + gates::SZZ, + GateSpec::new("SZZ") + .with_quantum_arity(2) + .with_category(GateCategory::TwoQubitUnitary), + ); + self.set_core_spec( + gates::SZZdg, + GateSpec::new("SZZdg") + .with_quantum_arity(2) + .with_category(GateCategory::TwoQubitUnitary), + ); // Two-qubit parameterized self.set_core_spec( diff --git a/exp/pecos-neo/src/extensible/gate_id.rs b/exp/pecos-neo/src/extensible/gate_id.rs index 73d9eed31..d6472d3c0 100644 --- a/exp/pecos-neo/src/extensible/gate_id.rs +++ b/exp/pecos-neo/src/extensible/gate_id.rs @@ -67,6 +67,8 @@ pub mod gates { pub const SYdg: GateId = GateId(14); pub const SZ: GateId = GateId(15); pub const SZdg: GateId = GateId(16); + pub const F: GateId = GateId(17); + pub const Fdg: GateId = GateId(18); // T gates pub const T: GateId = GateId(20); diff --git a/exp/pecos-neo/src/extensible/queue_validation.rs b/exp/pecos-neo/src/extensible/queue_validation.rs index a0c8737a3..daf559bee 100644 --- a/exp/pecos-neo/src/extensible/queue_validation.rs +++ b/exp/pecos-neo/src/extensible/queue_validation.rs @@ -149,6 +149,8 @@ pub fn is_clifford_gate_type(gate_type: GateType) -> bool { | GateType::Y | GateType::Z | GateType::H + | GateType::F + | GateType::Fdg | GateType::SX | GateType::SXdg | GateType::SY @@ -160,6 +162,10 @@ pub fn is_clifford_gate_type(gate_type: GateType) -> bool { | GateType::CZ | GateType::SZZ | GateType::SZZdg + | GateType::SXX + | GateType::SXXdg + | GateType::SYY + | GateType::SYYdg | GateType::SWAP | GateType::MZ | GateType::MeasureLeaked diff --git a/exp/pecos-neo/src/extensible/registry.rs b/exp/pecos-neo/src/extensible/registry.rs index 946b6a916..d47d52f95 100644 --- a/exp/pecos-neo/src/extensible/registry.rs +++ b/exp/pecos-neo/src/extensible/registry.rs @@ -62,6 +62,14 @@ impl GateRegistry { gates::H, &GateSpec::new("H").with_category(GateCategory::SingleQubitUnitary), ); + self.set_core( + gates::F, + &GateSpec::new("F").with_category(GateCategory::SingleQubitUnitary), + ); + self.set_core( + gates::Fdg, + &GateSpec::new("Fdg").with_category(GateCategory::SingleQubitUnitary), + ); self.set_core( gates::SX, &GateSpec::new("SX").with_category(GateCategory::SingleQubitUnitary), diff --git a/exp/pecos-neo/src/extensible/snapper.rs b/exp/pecos-neo/src/extensible/snapper.rs index c68aaa7cd..fa1f602c9 100644 --- a/exp/pecos-neo/src/extensible/snapper.rs +++ b/exp/pecos-neo/src/extensible/snapper.rs @@ -141,7 +141,7 @@ impl AngleSnapper { /// Snap or return original (for permissive mode). #[must_use] pub fn snap_or_keep(&self, angle: Angle64) -> Angle64 { - self.snap(angle).map(|r| r.snapped).unwrap_or(angle) + self.snap(angle).map_or(angle, |r| r.snapped) } /// Snap or return original, with flag indicating if snapped. diff --git a/exp/pecos-neo/src/extensible/tests.rs b/exp/pecos-neo/src/extensible/tests.rs index a65fef47b..5ba2e2bb5 100644 --- a/exp/pecos-neo/src/extensible/tests.rs +++ b/exp/pecos-neo/src/extensible/tests.rs @@ -3,8 +3,225 @@ use super::validator::GateForValidation; use super::*; +use crate::command::{CommandBuilder, GateType as CommandGateType}; use pecos_core::{Angle64, QubitId}; +#[derive(Debug, Clone, Copy)] +struct StandardCliffordCase { + gate_type: CommandGateType, + gate_id: GateId, + name: &'static str, + arity: u8, + inverse: CommandGateType, +} + +fn standard_clifford_cases() -> &'static [StandardCliffordCase] { + use CommandGateType::{ + CX, CY, CZ, F, Fdg, H, I, SWAP, SX, SXX, SXXdg, SXdg, SY, SYY, SYYdg, SYdg, SZ, SZZ, SZZdg, + SZdg, X, Y, Z, + }; + + &[ + StandardCliffordCase { + gate_type: I, + gate_id: gates::I, + name: "I", + arity: 1, + inverse: I, + }, + StandardCliffordCase { + gate_type: X, + gate_id: gates::X, + name: "X", + arity: 1, + inverse: X, + }, + StandardCliffordCase { + gate_type: Y, + gate_id: gates::Y, + name: "Y", + arity: 1, + inverse: Y, + }, + StandardCliffordCase { + gate_type: Z, + gate_id: gates::Z, + name: "Z", + arity: 1, + inverse: Z, + }, + StandardCliffordCase { + gate_type: H, + gate_id: gates::H, + name: "H", + arity: 1, + inverse: H, + }, + StandardCliffordCase { + gate_type: F, + gate_id: gates::F, + name: "F", + arity: 1, + inverse: Fdg, + }, + StandardCliffordCase { + gate_type: Fdg, + gate_id: gates::Fdg, + name: "Fdg", + arity: 1, + inverse: F, + }, + StandardCliffordCase { + gate_type: SX, + gate_id: gates::SX, + name: "SX", + arity: 1, + inverse: SXdg, + }, + StandardCliffordCase { + gate_type: SXdg, + gate_id: gates::SXdg, + name: "SXdg", + arity: 1, + inverse: SX, + }, + StandardCliffordCase { + gate_type: SY, + gate_id: gates::SY, + name: "SY", + arity: 1, + inverse: SYdg, + }, + StandardCliffordCase { + gate_type: SYdg, + gate_id: gates::SYdg, + name: "SYdg", + arity: 1, + inverse: SY, + }, + StandardCliffordCase { + gate_type: SZ, + gate_id: gates::SZ, + name: "SZ", + arity: 1, + inverse: SZdg, + }, + StandardCliffordCase { + gate_type: SZdg, + gate_id: gates::SZdg, + name: "SZdg", + arity: 1, + inverse: SZ, + }, + StandardCliffordCase { + gate_type: CX, + gate_id: gates::CX, + name: "CX", + arity: 2, + inverse: CX, + }, + StandardCliffordCase { + gate_type: CY, + gate_id: gates::CY, + name: "CY", + arity: 2, + inverse: CY, + }, + StandardCliffordCase { + gate_type: CZ, + gate_id: gates::CZ, + name: "CZ", + arity: 2, + inverse: CZ, + }, + StandardCliffordCase { + gate_type: SXX, + gate_id: gates::SXX, + name: "SXX", + arity: 2, + inverse: SXXdg, + }, + StandardCliffordCase { + gate_type: SXXdg, + gate_id: gates::SXXdg, + name: "SXXdg", + arity: 2, + inverse: SXX, + }, + StandardCliffordCase { + gate_type: SYY, + gate_id: gates::SYY, + name: "SYY", + arity: 2, + inverse: SYYdg, + }, + StandardCliffordCase { + gate_type: SYYdg, + gate_id: gates::SYYdg, + name: "SYYdg", + arity: 2, + inverse: SYY, + }, + StandardCliffordCase { + gate_type: SZZ, + gate_id: gates::SZZ, + name: "SZZ", + arity: 2, + inverse: SZZdg, + }, + StandardCliffordCase { + gate_type: SZZdg, + gate_id: gates::SZZdg, + name: "SZZdg", + arity: 2, + inverse: SZZ, + }, + StandardCliffordCase { + gate_type: SWAP, + gate_id: gates::SWAP, + name: "SWAP", + arity: 2, + inverse: SWAP, + }, + ] +} + +fn command_from_builder(gate_type: CommandGateType) -> crate::command::GateCommand { + let queue = match gate_type { + CommandGateType::I => CommandBuilder::new().identity(&[0]).build(), + CommandGateType::X => CommandBuilder::new().x(&[0]).build(), + CommandGateType::Y => CommandBuilder::new().y(&[0]).build(), + CommandGateType::Z => CommandBuilder::new().z(&[0]).build(), + CommandGateType::H => CommandBuilder::new().h(&[0]).build(), + CommandGateType::F => CommandBuilder::new().f(&[0]).build(), + CommandGateType::Fdg => CommandBuilder::new().fdg(&[0]).build(), + CommandGateType::SX => CommandBuilder::new().sx(&[0]).build(), + CommandGateType::SXdg => CommandBuilder::new().sxdg(&[0]).build(), + CommandGateType::SY => CommandBuilder::new().sy(&[0]).build(), + CommandGateType::SYdg => CommandBuilder::new().sydg(&[0]).build(), + CommandGateType::SZ => CommandBuilder::new().sz(&[0]).build(), + CommandGateType::SZdg => CommandBuilder::new().szdg(&[0]).build(), + CommandGateType::CX => CommandBuilder::new().cx(&[(0, 1)]).build(), + CommandGateType::CY => CommandBuilder::new().cy(&[(0, 1)]).build(), + CommandGateType::CZ => CommandBuilder::new().cz(&[(0, 1)]).build(), + CommandGateType::SXX => CommandBuilder::new().sxx(&[(0, 1)]).build(), + CommandGateType::SXXdg => CommandBuilder::new().sxxdg(&[(0, 1)]).build(), + CommandGateType::SYY => CommandBuilder::new().syy(&[(0, 1)]).build(), + CommandGateType::SYYdg => CommandBuilder::new().syydg(&[(0, 1)]).build(), + CommandGateType::SZZ => CommandBuilder::new().szz(&[(0, 1)]).build(), + CommandGateType::SZZdg => CommandBuilder::new().szzdg(&[(0, 1)]).build(), + CommandGateType::SWAP => CommandBuilder::new().swap(&[(0, 1)]).build(), + other => panic!("not a standard Clifford conformance gate: {other:?}"), + }; + + assert_eq!( + queue.len(), + 1, + "{gate_type:?} builder should emit one command" + ); + queue.iter().next().unwrap().clone() +} + // ============================================================================ // GateId Tests // ============================================================================ @@ -1266,6 +1483,78 @@ fn test_validator_is_gate_allowed() { assert!(!validator.is_gate_allowed(gates::RZ, &[Angle64::from_turns(0.1)], ®istry)); } +#[test] +fn test_standard_cliffords_are_registered_defined_and_allowed() { + let registry = GateRegistry::new(); + let definitions = GateDefinitions::new(); + let validator = CliffordValidator::new(); + + for case in standard_clifford_cases() { + assert!( + registry.get(case.gate_id).is_some(), + "missing registry spec for {}", + case.name + ); + assert!( + definitions.spec(case.gate_id).is_some(), + "missing gate definition for {}", + case.name + ); + assert!( + validator.is_gate_allowed(case.gate_id, &[], ®istry), + "Clifford validator should allow {}", + case.name + ); + } +} + +#[test] +fn test_standard_clifford_gate_surface_is_consistent() { + let registry = GateRegistry::new(); + let definitions = GateDefinitions::new(); + + for case in standard_clifford_cases() { + let registry_spec = registry.get(case.gate_id).unwrap(); + let definition_spec = definitions.spec(case.gate_id).unwrap(); + assert_eq!(registry_spec.name, case.name, "{case:?}"); + assert_eq!(definition_spec.name, case.name, "{case:?}"); + assert_eq!(registry_spec.quantum_arity, case.arity, "{case:?}"); + assert_eq!(definition_spec.quantum_arity, case.arity, "{case:?}"); + assert_eq!( + case.gate_type.quantum_arity(), + case.arity as usize, + "{case:?}" + ); + assert_eq!(case.gate_type.angle_arity(), 0, "{case:?}"); + assert_eq!(case.gate_type.to_gate_id(), case.gate_id, "{case:?}"); + assert_eq!( + case.gate_id.try_to_gate_type(), + Some(case.gate_type), + "{case:?}" + ); + + let command = command_from_builder(case.gate_type); + assert_eq!(command.gate_type, case.gate_type, "{case:?}"); + assert_eq!(command.qubits.len(), case.arity as usize, "{case:?}"); + assert!(command.angles.is_empty(), "{case:?}"); + } +} + +#[test] +fn test_standard_clifford_inverse_table_is_symmetric() { + for case in standard_clifford_cases() { + let inverse = standard_clifford_cases() + .iter() + .find(|candidate| candidate.gate_type == case.inverse) + .unwrap_or_else(|| panic!("missing inverse {:?} for {}", case.inverse, case.name)); + assert_eq!( + inverse.inverse, case.gate_type, + "inverse table should be symmetric for {}", + case.name + ); + } +} + #[test] fn test_validation_error_display() { let err = ValidationError::ForbiddenGate { @@ -1294,7 +1583,7 @@ fn test_validation_error_display() { #[test] fn test_standard_adaptor_can_adapt() { - let adaptor = StandardAdaptor::clifford_rz(); + let adaptor = StandardAdaptor::stab_vec(); assert!(adaptor.can_adapt(gates::T)); assert!(adaptor.can_adapt(gates::Tdg)); @@ -1312,7 +1601,7 @@ fn test_standard_adaptor_can_adapt() { #[test] fn test_standard_adaptor_t_gate() { - let adaptor = StandardAdaptor::clifford_rz(); + let adaptor = StandardAdaptor::stab_vec(); let result = adaptor.adapt(gates::T, &[QubitId(0)], &[]); @@ -1325,7 +1614,7 @@ fn test_standard_adaptor_t_gate() { #[test] fn test_standard_adaptor_tdg_gate() { - let adaptor = StandardAdaptor::clifford_rz(); + let adaptor = StandardAdaptor::stab_vec(); let result = adaptor.adapt(gates::Tdg, &[QubitId(0)], &[]); @@ -1338,7 +1627,7 @@ fn test_standard_adaptor_tdg_gate() { #[test] fn test_standard_adaptor_rx_gate() { - let adaptor = StandardAdaptor::clifford_rz(); + let adaptor = StandardAdaptor::stab_vec(); let theta = Angle64::QUARTER_TURN; let result = adaptor.adapt(gates::RX, &[QubitId(0)], &[theta]); @@ -1353,7 +1642,7 @@ fn test_standard_adaptor_rx_gate() { #[test] fn test_standard_adaptor_swap_gate() { - let adaptor = StandardAdaptor::clifford_rz(); + let adaptor = StandardAdaptor::stab_vec(); let result = adaptor.adapt(gates::SWAP, &[QubitId(0), QubitId(1)], &[]); @@ -1364,7 +1653,7 @@ fn test_standard_adaptor_swap_gate() { #[test] fn test_standard_adaptor_rzz_gate() { - let adaptor = StandardAdaptor::clifford_rz(); + let adaptor = StandardAdaptor::stab_vec(); let theta = Angle64::QUARTER_TURN; let result = adaptor.adapt(gates::RZZ, &[QubitId(0), QubitId(1)], &[theta]); @@ -1379,7 +1668,7 @@ fn test_standard_adaptor_rzz_gate() { #[test] fn test_standard_adaptor_ccx_gate() { - let adaptor = StandardAdaptor::clifford_rz(); + let adaptor = StandardAdaptor::stab_vec(); let result = adaptor.adapt(gates::CCX, &[QubitId(0), QubitId(1), QubitId(2)], &[]); @@ -1394,7 +1683,7 @@ fn test_standard_adaptor_ccx_gate() { #[test] fn test_composite_adaptor() { - let adaptor = CompositeAdaptor::new().with(StandardAdaptor::clifford_rz()); + let adaptor = CompositeAdaptor::new().with(StandardAdaptor::stab_vec()); assert!(adaptor.can_adapt(gates::T)); assert!(adaptor.can_adapt(gates::SWAP)); @@ -1432,7 +1721,7 @@ fn test_custom_adaptor() { #[test] fn test_adaptor_adaptable_gates() { - let adaptor = StandardAdaptor::clifford_rz(); + let adaptor = StandardAdaptor::stab_vec(); let adaptable = adaptor.adaptable_gates(); assert!(adaptable.contains(gates::T)); diff --git a/exp/pecos-neo/src/extensible/user_gates.rs b/exp/pecos-neo/src/extensible/user_gates.rs index 2cff2f8a3..cbe609a2b 100644 --- a/exp/pecos-neo/src/extensible/user_gates.rs +++ b/exp/pecos-neo/src/extensible/user_gates.rs @@ -204,11 +204,8 @@ impl GatePlugin for UserGatesPlugin { } fn build(&self, registry: &mut DecompositionRegistry) { - let mut current_id = self.next_id; - - for def in &self.definitions { + for (current_id, def) in (self.next_id..).zip(self.definitions.iter()) { let gate_id = GateId(current_id); - current_id += 1; if let Some(ops) = &def.decomposition { registry.register_dynamic(gate_id, def.requires.clone(), ops.clone()); diff --git a/exp/pecos-neo/src/extensible/validator.rs b/exp/pecos-neo/src/extensible/validator.rs index 7635f4673..758982989 100644 --- a/exp/pecos-neo/src/extensible/validator.rs +++ b/exp/pecos-neo/src/extensible/validator.rs @@ -141,6 +141,8 @@ impl CliffordValidator { // Cliffords allowed_gates.insert(gates::H); + allowed_gates.insert(gates::F); + allowed_gates.insert(gates::Fdg); allowed_gates.insert(gates::SX); allowed_gates.insert(gates::SXdg); allowed_gates.insert(gates::SY); @@ -154,6 +156,10 @@ impl CliffordValidator { allowed_gates.insert(gates::CZ); allowed_gates.insert(gates::SWAP); allowed_gates.insert(gates::ISWAP); + allowed_gates.insert(gates::SXX); + allowed_gates.insert(gates::SXXdg); + allowed_gates.insert(gates::SYY); + allowed_gates.insert(gates::SYYdg); allowed_gates.insert(gates::SZZ); allowed_gates.insert(gates::SZZdg); diff --git a/exp/pecos-neo/src/noise/composite/channel.rs b/exp/pecos-neo/src/noise/composite/channel.rs index 442840302..aeb3edc6f 100644 --- a/exp/pecos-neo/src/noise/composite/channel.rs +++ b/exp/pecos-neo/src/noise/composite/channel.rs @@ -1363,13 +1363,12 @@ mod tests { let response = channel.apply(&event, &mut ctx, &mut rng); match response { NoiseResponse::InjectGates(_) => pauli_count += 1, - NoiseResponse::Multiple(ref rs) => { + NoiseResponse::Multiple(ref rs) if rs .iter() - .any(|r| matches!(r, NoiseResponse::InjectGates(_))) - { - pauli_count += 1; - } + .any(|r| matches!(r, NoiseResponse::InjectGates(_))) => + { + pauli_count += 1; } _ => {} } @@ -1904,13 +1903,12 @@ mod tests { CompositeResponse::InjectGates(_) => { _partner_depolarize_count += 1; } - CompositeResponse::Multiple(ref parts) => { + CompositeResponse::Multiple(ref parts) if parts .iter() - .any(|p| matches!(p, CompositeResponse::InjectGates(_))) - { - _partner_depolarize_count += 1; - } + .any(|p| matches!(p, CompositeResponse::InjectGates(_))) => + { + _partner_depolarize_count += 1; } _ => {} } @@ -2107,13 +2105,12 @@ mod tests { let response = channel.apply(&layer_event, &mut ctx, &mut rng); match response { NoiseResponse::InjectGates(_) => z_count += 1, - NoiseResponse::Multiple(ref rs) => { + NoiseResponse::Multiple(ref rs) if rs .iter() - .any(|r| matches!(r, NoiseResponse::InjectGates(_))) - { - z_count += 1; - } + .any(|r| matches!(r, NoiseResponse::InjectGates(_))) => + { + z_count += 1; } _ => {} } diff --git a/exp/pecos-neo/src/noise/single_qubit.rs b/exp/pecos-neo/src/noise/single_qubit.rs index 109cb8a58..1cfa6342c 100644 --- a/exp/pecos-neo/src/noise/single_qubit.rs +++ b/exp/pecos-neo/src/noise/single_qubit.rs @@ -217,10 +217,12 @@ impl NoiseChannel for SingleQubitChannel { if self.error_probability <= 0.0 { return false; } - // Respond to BeforeGate for leaked qubit handling and AfterGate for noise + // Respond only to unitary single-qubit gates. + // Preparations (PZ, QAlloc) and measurements (MZ) have their own + // noise channels and should not get gate depolarizing noise. match event { NoiseEvent::BeforeGate { gate_type, .. } | NoiseEvent::AfterGate { gate_type, .. } => { - gate_type.is_single_qubit() + gate_type.is_single_qubit() && gate_type.is_unitary_gate() } _ => false, } @@ -272,7 +274,7 @@ impl NoiseChannel for SingleQubitChannel { NoiseEvent::BeforeGate { gate_type, qubits, .. } => { - if !gate_type.is_single_qubit() { + if !gate_type.is_single_qubit() || !gate_type.is_unitary_gate() { return None; } // Skip noise for noiseless gates (but still check leakage) @@ -284,7 +286,7 @@ impl NoiseChannel for SingleQubitChannel { NoiseEvent::AfterGate { gate_type, qubits, .. } => { - if !gate_type.is_single_qubit() { + if !gate_type.is_single_qubit() || !gate_type.is_unitary_gate() { return None; } // Skip noise for noiseless gates diff --git a/exp/pecos-neo/src/noise/two_qubit.rs b/exp/pecos-neo/src/noise/two_qubit.rs index bbfdeec0e..c5770993c 100644 --- a/exp/pecos-neo/src/noise/two_qubit.rs +++ b/exp/pecos-neo/src/noise/two_qubit.rs @@ -436,9 +436,12 @@ impl NoiseChannel for TwoQubitChannel { if self.error_probability <= 0.0 { return false; } + // Only respond to unitary two-qubit gates. + // Non-unitary two-qubit operations (if any) should not get + // gate depolarizing noise. match event { NoiseEvent::BeforeGate { gate_type, .. } | NoiseEvent::AfterGate { gate_type, .. } => { - gate_type.is_two_qubit() + gate_type.is_two_qubit() && gate_type.is_unitary_gate() } _ => false, } @@ -493,7 +496,7 @@ impl NoiseChannel for TwoQubitChannel { NoiseEvent::BeforeGate { gate_type, qubits, .. } => { - if !gate_type.is_two_qubit() { + if !gate_type.is_two_qubit() || !gate_type.is_unitary_gate() { return None; } if ctx.is_noiseless(*gate_type) { @@ -507,7 +510,7 @@ impl NoiseChannel for TwoQubitChannel { angles, .. } => { - if !gate_type.is_two_qubit() { + if !gate_type.is_two_qubit() || !gate_type.is_unitary_gate() { return None; } if ctx.is_noiseless(*gate_type) { diff --git a/exp/pecos-neo/src/runner.rs b/exp/pecos-neo/src/runner.rs index d1873d25d..64a2e3720 100644 --- a/exp/pecos-neo/src/runner.rs +++ b/exp/pecos-neo/src/runner.rs @@ -211,7 +211,7 @@ impl GateEventHandlers { fn insert(vec: &mut Vec, handler: ErasedGateHandler, priority: i32) { vec.push(PrioritizedHandler { handler, priority }); // Stable sort so same-priority handlers keep registration order - vec.sort_by(|a, b| b.priority.cmp(&a.priority)); + vec.sort_by_key(|h| std::cmp::Reverse(h.priority)); } /// Dispatch all handlers in a Vec and combine their responses. @@ -789,7 +789,7 @@ impl CircuitRunner { fn merge_vec(dst: &mut Vec, src: Vec) { if !src.is_empty() { dst.extend(src); - dst.sort_by(|a, b| b.priority.cmp(&a.priority)); + dst.sort_by_key(|h| std::cmp::Reverse(h.priority)); } } merge_vec( @@ -1443,6 +1443,14 @@ impl CircuitRunner { sim.h(qubits); true } + GateType::F => { + sim.f(qubits); + true + } + GateType::Fdg => { + sim.fdg(qubits); + true + } GateType::SX => { sim.sx(qubits); true @@ -1492,6 +1500,26 @@ impl CircuitRunner { sim.szzdg(&pairs); true } + GateType::SXX => { + let pairs = flat_to_pairs(qubits); + sim.sxx(&pairs); + true + } + GateType::SXXdg => { + let pairs = flat_to_pairs(qubits); + sim.sxxdg(&pairs); + true + } + GateType::SYY => { + let pairs = flat_to_pairs(qubits); + sim.syy(&pairs); + true + } + GateType::SYYdg => { + let pairs = flat_to_pairs(qubits); + sim.syydg(&pairs); + true + } GateType::SWAP => { let pairs = flat_to_pairs(qubits); sim.swap(&pairs); @@ -1566,9 +1594,9 @@ impl CircuitRunner { // Perform measurement let results = sim.mz(&[qubit]); - let meas_result = results.first(); - let outcome = meas_result.is_some_and(|r| r.outcome); - let is_deterministic = meas_result.is_none_or(|r| r.is_deterministic); + let meas_id = results.first(); + let outcome = meas_id.is_some_and(|r| r.outcome); + let is_deterministic = meas_id.is_none_or(|r| r.is_deterministic); // Store result for conditionals if let Some(slot) = self.results.get_mut(result_id.0 as usize) { @@ -2062,7 +2090,7 @@ impl CircuitRunner { NoiseResponse::InjectGates(gates) => { for gate in gates.iter() { - Self::execute_noise_gate(sim, gate); + self.execute_noise_gate(sim, gate); } } @@ -2092,8 +2120,11 @@ impl CircuitRunner { } } - /// Execute a noise gate (injected Pauli error). - fn execute_noise_gate(sim: &mut S, gate: &GateCommand) { + /// Execute a noise gate (injected error). + /// + /// Handles Pauli gates directly. For non-Pauli gates (rotations, Cliffords), + /// delegates to the rotation executor if available, otherwise skips. + fn execute_noise_gate(&self, sim: &mut S, gate: &GateCommand) { let qubits = gate.qubits.as_slice(); match gate.gate_type { GateType::X => { @@ -2105,7 +2136,81 @@ impl CircuitRunner { GateType::Z => { sim.z(qubits); } - _ => {} + GateType::H => { + sim.h(qubits); + } + GateType::F => { + sim.f(qubits); + } + GateType::Fdg => { + sim.fdg(qubits); + } + GateType::SX => { + sim.sx(qubits); + } + GateType::SXdg => { + sim.sxdg(qubits); + } + GateType::SY => { + sim.sy(qubits); + } + GateType::SYdg => { + sim.sydg(qubits); + } + GateType::SZ => { + sim.sz(qubits); + } + GateType::SZdg => { + sim.szdg(qubits); + } + GateType::CX => { + let pairs: Vec<_> = qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + sim.cx(&pairs); + } + GateType::CY => { + let pairs: Vec<_> = qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + sim.cy(&pairs); + } + GateType::CZ => { + let pairs: Vec<_> = qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + sim.cz(&pairs); + } + GateType::SXX => { + let pairs: Vec<_> = qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + sim.sxx(&pairs); + } + GateType::SXXdg => { + let pairs: Vec<_> = qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + sim.sxxdg(&pairs); + } + GateType::SYY => { + let pairs: Vec<_> = qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + sim.syy(&pairs); + } + GateType::SYYdg => { + let pairs: Vec<_> = qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + sim.syydg(&pairs); + } + GateType::SZZ => { + let pairs: Vec<_> = qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + sim.szz(&pairs); + } + GateType::SZZdg => { + let pairs: Vec<_> = qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + sim.szzdg(&pairs); + } + GateType::SWAP => { + let pairs: Vec<_> = qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + sim.swap(&pairs); + } + // Non-Clifford gates: delegate to rotation executor + other => { + if let Some(executor) = self.rotation_executor { + executor(sim, GateId::from(other), gate.angles.as_slice(), qubits); + } + // If no rotation executor, silently skip (noise channel injected + // a gate the simulator can't handle). + } } } } @@ -2248,46 +2353,38 @@ where } } // CRZ decomposition: RZ(theta/2), CX, RZ(-theta/2), CX - GateType::CRZ => { - if qubits.len() >= 2 { - let control = qubits[0]; - let target = qubits[1]; - let angle = angles.first().copied().unwrap_or(Angle64::ZERO); - let half_angle = angle / 2u64; - sim.rz(half_angle, &[target]); - sim.cx(&[(control, target)]); - sim.rz(-half_angle, &[target]); - sim.cx(&[(control, target)]); - true - } else { - false - } + GateType::CRZ if qubits.len() >= 2 => { + let control = qubits[0]; + let target = qubits[1]; + let angle = angles.first().copied().unwrap_or(Angle64::ZERO); + let half_angle = angle / 2u64; + sim.rz(half_angle, &[target]); + sim.cx(&[(control, target)]); + sim.rz(-half_angle, &[target]); + sim.cx(&[(control, target)]); + true } // CCX (Toffoli) decomposition - GateType::CCX => { - if qubits.len() >= 3 { - let c1 = qubits[0]; - let c2 = qubits[1]; - let target = qubits[2]; - sim.h(&[target]); - sim.cx(&[(c2, target)]); - sim.tdg(&[target]); - sim.cx(&[(c1, target)]); - sim.t(&[target]); - sim.cx(&[(c2, target)]); - sim.tdg(&[target]); - sim.cx(&[(c1, target)]); - sim.t(&[c2]); - sim.t(&[target]); - sim.h(&[target]); - sim.cx(&[(c1, c2)]); - sim.t(&[c1]); - sim.tdg(&[c2]); - sim.cx(&[(c1, c2)]); - true - } else { - false - } + GateType::CCX if qubits.len() >= 3 => { + let c1 = qubits[0]; + let c2 = qubits[1]; + let target = qubits[2]; + sim.h(&[target]); + sim.cx(&[(c2, target)]); + sim.tdg(&[target]); + sim.cx(&[(c1, target)]); + sim.t(&[target]); + sim.cx(&[(c2, target)]); + sim.tdg(&[target]); + sim.cx(&[(c1, target)]); + sim.t(&[c2]); + sim.t(&[target]); + sim.h(&[target]); + sim.cx(&[(c1, c2)]); + sim.t(&[c1]); + sim.tdg(&[c2]); + sim.cx(&[(c1, c2)]); + true } _ => false, } @@ -2300,6 +2397,9 @@ mod tests { use crate::command::CommandBuilder; use crate::extensible::{GateCategory, GateSpec, OpBuilder, gates}; use crate::noise::single_qubit::SingleQubitChannel; + use num_complex::Complex64; + use pecos_core::clifford::Clifford; + use pecos_quantum::unitary_matrix::{ToMatrix, UnitaryMatrix}; use pecos_simulators::{SparseStab, StateVec}; // --- Basic execution tests --- @@ -2942,4 +3042,224 @@ mod tests { let outcomes = runner.take_outcomes(); assert_eq!(outcomes.len(), 1); } + + #[test] + fn test_apply_gate_standard_clifford_inverse_sequences() { + let mut state = SparseStab::new(2); + let mut runner = CircuitRunner::::new().with_seed(42); + + runner + .apply_gate(&mut state, GateType::PZ, &[QubitId(0), QubitId(1)], &[]) + .unwrap(); + runner + .apply_gate(&mut state, GateType::F, &[QubitId(0)], &[]) + .unwrap(); + runner + .apply_gate(&mut state, GateType::Fdg, &[QubitId(0)], &[]) + .unwrap(); + runner + .apply_gate(&mut state, GateType::SXX, &[QubitId(0), QubitId(1)], &[]) + .unwrap(); + runner + .apply_gate(&mut state, GateType::SXXdg, &[QubitId(0), QubitId(1)], &[]) + .unwrap(); + runner + .apply_gate(&mut state, GateType::MZ, &[QubitId(0), QubitId(1)], &[]) + .unwrap(); + + let outcomes = runner.take_outcomes(); + assert_eq!(outcomes.len(), 2); + for outcome in outcomes.iter() { + assert!( + !outcome.outcome, + "inverse Clifford sequence should preserve |0>" + ); + assert!(outcome.is_deterministic); + } + } + + #[test] + fn test_apply_gate_standard_clifford_inverse_table() { + let cases = [ + (GateType::I, GateType::I, vec![QubitId(0)]), + (GateType::X, GateType::X, vec![QubitId(0)]), + (GateType::Y, GateType::Y, vec![QubitId(0)]), + (GateType::Z, GateType::Z, vec![QubitId(0)]), + (GateType::H, GateType::H, vec![QubitId(0)]), + (GateType::F, GateType::Fdg, vec![QubitId(0)]), + (GateType::Fdg, GateType::F, vec![QubitId(0)]), + (GateType::SX, GateType::SXdg, vec![QubitId(0)]), + (GateType::SXdg, GateType::SX, vec![QubitId(0)]), + (GateType::SY, GateType::SYdg, vec![QubitId(0)]), + (GateType::SYdg, GateType::SY, vec![QubitId(0)]), + (GateType::SZ, GateType::SZdg, vec![QubitId(0)]), + (GateType::SZdg, GateType::SZ, vec![QubitId(0)]), + (GateType::CX, GateType::CX, vec![QubitId(0), QubitId(1)]), + (GateType::CY, GateType::CY, vec![QubitId(0), QubitId(1)]), + (GateType::CZ, GateType::CZ, vec![QubitId(0), QubitId(1)]), + (GateType::SXX, GateType::SXXdg, vec![QubitId(0), QubitId(1)]), + (GateType::SXXdg, GateType::SXX, vec![QubitId(0), QubitId(1)]), + (GateType::SYY, GateType::SYYdg, vec![QubitId(0), QubitId(1)]), + (GateType::SYYdg, GateType::SYY, vec![QubitId(0), QubitId(1)]), + (GateType::SZZ, GateType::SZZdg, vec![QubitId(0), QubitId(1)]), + (GateType::SZZdg, GateType::SZZ, vec![QubitId(0), QubitId(1)]), + (GateType::SWAP, GateType::SWAP, vec![QubitId(0), QubitId(1)]), + ]; + + for (gate, inverse, qubits) in cases { + let mut state = SparseStab::new(2); + let mut runner = CircuitRunner::::new().with_seed(42); + + runner + .apply_gate(&mut state, GateType::PZ, &[QubitId(0), QubitId(1)], &[]) + .unwrap(); + runner.apply_gate(&mut state, gate, &qubits, &[]).unwrap(); + runner + .apply_gate(&mut state, inverse, &qubits, &[]) + .unwrap(); + runner + .apply_gate(&mut state, GateType::MZ, &[QubitId(0), QubitId(1)], &[]) + .unwrap(); + + let outcomes = runner.take_outcomes(); + assert_eq!(outcomes.len(), 2, "{gate:?} then {inverse:?}"); + for outcome in outcomes.iter() { + assert!( + !outcome.outcome, + "{gate:?} then {inverse:?} should preserve |00>" + ); + assert!(outcome.is_deterministic); + } + } + } + + fn matrix_times_state(matrix: &UnitaryMatrix, state: &[Complex64]) -> Vec { + (0..matrix.nrows()) + .map(|row| { + let mut value = Complex64::new(0.0, 0.0); + for col in 0..matrix.ncols() { + value += matrix[(row, col)] * state[col]; + } + value + }) + .collect() + } + + fn assert_states_close(actual: &[Complex64], expected: &[Complex64], label: &str) { + const TOLERANCE: f64 = 1e-10; + assert_eq!(actual.len(), expected.len(), "{label}"); + + let phase = actual + .iter() + .zip(expected.iter()) + .find(|(a, e)| a.norm() > TOLERANCE || e.norm() > TOLERANCE) + .map(|(a, e)| { + assert!( + a.norm() > TOLERANCE && e.norm() > TOLERANCE, + "{label}: support differs, actual={a:?}, expected={e:?}" + ); + *a / *e + }) + .unwrap_or(Complex64::new(1.0, 0.0)); + + for (idx, (a, e)) in actual.iter().zip(expected.iter()).enumerate() { + let diff = (*a - phase * *e).norm(); + assert!( + diff < TOLERANCE, + "{label}: amplitude {idx} differs up to global phase {phase:?}, actual={a:?}, expected={e:?}, diff={diff}" + ); + } + } + + fn prepare_matrix_test_state(prep_index: usize) -> StateVec { + let mut state = StateVec::new(2); + match prep_index { + 0 => {} + 1 => { + state.x(&[QubitId(0)]); + } + 2 => { + state.x(&[QubitId(1)]); + } + 3 => { + state.h(&[QubitId(0)]); + state.cx(&[(QubitId(0), QubitId(1))]); + } + 4 => { + state.sx(&[QubitId(0)]); + state.h(&[QubitId(1)]); + } + _ => unreachable!(), + } + state + } + + #[test] + fn test_apply_gate_standard_cliffords_match_unitary_matrices() { + let one_qubit_cases = [ + (GateType::I, Clifford::I), + (GateType::X, Clifford::X), + (GateType::Y, Clifford::Y), + (GateType::Z, Clifford::Z), + (GateType::H, Clifford::H), + (GateType::F, Clifford::F), + (GateType::Fdg, Clifford::Fdg), + (GateType::SX, Clifford::SX), + (GateType::SXdg, Clifford::SXdg), + (GateType::SY, Clifford::SY), + (GateType::SYdg, Clifford::SYdg), + (GateType::SZ, Clifford::SZ), + (GateType::SZdg, Clifford::SZdg), + ]; + let two_qubit_cases = [ + (GateType::CX, Clifford::CX), + (GateType::CY, Clifford::CY), + (GateType::CZ, Clifford::CZ), + (GateType::SXX, Clifford::SXX), + (GateType::SXXdg, Clifford::SXXdg), + (GateType::SYY, Clifford::SYY), + (GateType::SYYdg, Clifford::SYYdg), + (GateType::SZZ, Clifford::SZZ), + (GateType::SZZdg, Clifford::SZZdg), + (GateType::SWAP, Clifford::SWAP), + ]; + + for prep_index in 0..5 { + for (gate_type, clifford) in one_qubit_cases { + let mut state = prepare_matrix_test_state(prep_index); + let input = state.state(); + let expected = matrix_times_state(&clifford.on_qubit(1).to_matrix(), &input); + + let mut runner = CircuitRunner::::new().with_seed(42); + runner + .apply_gate(&mut state, gate_type, &[QubitId(1)], &[]) + .unwrap(); + let actual = state.state(); + + assert_states_close( + &actual, + &expected, + &format!("{gate_type:?} on prep {prep_index}"), + ); + } + + for (gate_type, clifford) in two_qubit_cases { + let mut state = prepare_matrix_test_state(prep_index); + let input = state.state(); + let expected = matrix_times_state(&clifford.on_qubits(0, 1).to_matrix(), &input); + + let mut runner = CircuitRunner::::new().with_seed(42); + runner + .apply_gate(&mut state, gate_type, &[QubitId(0), QubitId(1)], &[]) + .unwrap(); + let actual = state.state(); + + assert_states_close( + &actual, + &expected, + &format!("{gate_type:?} on prep {prep_index}"), + ); + } + } + } } diff --git a/exp/pecos-neo/src/sampling/importance_runner.rs b/exp/pecos-neo/src/sampling/importance_runner.rs index 22f189e6d..bcf1bf036 100644 --- a/exp/pecos-neo/src/sampling/importance_runner.rs +++ b/exp/pecos-neo/src/sampling/importance_runner.rs @@ -630,6 +630,12 @@ impl ImportanceSamplingRunner { GateType::H => { self.simulator.h(&qubits); } + GateType::F => { + self.simulator.f(&qubits); + } + GateType::Fdg => { + self.simulator.fdg(&qubits); + } GateType::SX => { self.simulator.sx(&qubits); } @@ -675,6 +681,26 @@ impl ImportanceSamplingRunner { qubits.chunks_exact(2).map(|c| (c[0], c[1])).collect(); self.simulator.szzdg(&pairs); } + GateType::SXX => { + let pairs: Vec<(QubitId, QubitId)> = + qubits.chunks_exact(2).map(|c| (c[0], c[1])).collect(); + self.simulator.sxx(&pairs); + } + GateType::SXXdg => { + let pairs: Vec<(QubitId, QubitId)> = + qubits.chunks_exact(2).map(|c| (c[0], c[1])).collect(); + self.simulator.sxxdg(&pairs); + } + GateType::SYY => { + let pairs: Vec<(QubitId, QubitId)> = + qubits.chunks_exact(2).map(|c| (c[0], c[1])).collect(); + self.simulator.syy(&pairs); + } + GateType::SYYdg => { + let pairs: Vec<(QubitId, QubitId)> = + qubits.chunks_exact(2).map(|c| (c[0], c[1])).collect(); + self.simulator.syydg(&pairs); + } GateType::SWAP => { let pairs: Vec<(QubitId, QubitId)> = qubits.chunks_exact(2).map(|c| (c[0], c[1])).collect(); @@ -892,6 +918,25 @@ mod tests { // (unless by chance the proposal probability matched the decision) } + #[test] + fn test_importance_runner_handles_face_inverse_deterministically() { + let commands = CommandBuilder::new() + .pz(&[0]) + .f(&[0]) + .fdg(&[0]) + .mz(&[0]) + .build(); + + let mut runner = ImportanceSamplingRunner::new(SparseStab::new(1)).with_seed(42); + let result = runner.run_shot(&commands); + + assert_eq!(result.outcomes.len(), 1); + let outcome = result.outcomes.get(QubitId(0)).unwrap(); + assert!(!outcome.outcome); + assert!(outcome.is_deterministic); + assert!((result.weight.weight() - 1.0).abs() < 1e-10); + } + #[test] fn test_importance_sampling_estimates_correct_rate() { // This test verifies that importance sampling produces diff --git a/exp/pecos-neo/src/sampling/path.rs b/exp/pecos-neo/src/sampling/path.rs index 2fe42db37..d6f3cc705 100644 --- a/exp/pecos-neo/src/sampling/path.rs +++ b/exp/pecos-neo/src/sampling/path.rs @@ -535,6 +535,12 @@ impl PathExplorer { GateType::H => { self.simulator.h(&qubits); } + GateType::F => { + self.simulator.f(&qubits); + } + GateType::Fdg => { + self.simulator.fdg(&qubits); + } GateType::SX => { self.simulator.sx(&qubits); } @@ -578,6 +584,26 @@ impl PathExplorer { qubits.chunks_exact(2).map(|c| (c[0], c[1])).collect(); self.simulator.szzdg(&pairs); } + GateType::SXX => { + let pairs: Vec<(QubitId, QubitId)> = + qubits.chunks_exact(2).map(|c| (c[0], c[1])).collect(); + self.simulator.sxx(&pairs); + } + GateType::SXXdg => { + let pairs: Vec<(QubitId, QubitId)> = + qubits.chunks_exact(2).map(|c| (c[0], c[1])).collect(); + self.simulator.sxxdg(&pairs); + } + GateType::SYY => { + let pairs: Vec<(QubitId, QubitId)> = + qubits.chunks_exact(2).map(|c| (c[0], c[1])).collect(); + self.simulator.syy(&pairs); + } + GateType::SYYdg => { + let pairs: Vec<(QubitId, QubitId)> = + qubits.chunks_exact(2).map(|c| (c[0], c[1])).collect(); + self.simulator.syydg(&pairs); + } GateType::SWAP => { let pairs: Vec<(QubitId, QubitId)> = qubits.chunks_exact(2).map(|c| (c[0], c[1])).collect(); @@ -759,6 +785,42 @@ mod tests { assert!(result1.outcomes.get_bit(QubitId(0)).unwrap()); } + #[test] + fn test_path_explorer_records_face_inverse_as_deterministic() { + let commands = CommandBuilder::new() + .pz(&[0]) + .f(&[0]) + .fdg(&[0]) + .mz(&[0]) + .build(); + + let mut explorer = PathExplorer::new(SparseStab::new(1)).with_seed(42); + let result = explorer.run_and_record(&commands); + + assert!(!result.outcomes.get_bit(QubitId(0)).unwrap()); + assert_eq!(result.path.len(), 1); + let path_outcome = result.path.get(0).unwrap(); + assert!(!path_outcome.outcome); + assert!(path_outcome.is_deterministic); + } + + #[test] + fn test_path_explorer_replays_face_inverse_as_deterministic() { + let commands = CommandBuilder::new() + .pz(&[0]) + .f(&[0]) + .fdg(&[0]) + .mz(&[0]) + .build(); + let mut explorer = PathExplorer::new(SparseStab::new(1)); + let forced_one = EnumeratedPath { bits: 1, len: 1 }; + + let result = explorer.run_with_path(&commands, &forced_one); + + assert!(!result.outcomes.get_bit(QubitId(0)).unwrap()); + assert!(result.path.get(0).unwrap().is_deterministic); + } + #[test] fn test_path_enumeration_statistics() { // Simple circuit: H then measure diff --git a/exp/pecos-neo/src/tool.rs b/exp/pecos-neo/src/tool.rs index 478c23224..26002d83a 100644 --- a/exp/pecos-neo/src/tool.rs +++ b/exp/pecos-neo/src/tool.rs @@ -96,11 +96,11 @@ pub use importance::{ pub use plugin::{Plugin, PluginGroup}; pub use resource::{Resource, Resources}; pub use simulation::{ - Circuit, CustomBackendBuilder, ImportanceSamplingBuilder, NoiseResource, Orchestrator, + Circuit, CustomBackendBuilder, ImportanceSamplingBuilder, NoiseResource, Sampling, QuantumBackend, SimConfig, SimNeoBuilder, SimNeoInput, Simulation, SimulationResults, SimulatorFactory, SparseStabBuilder, StateVecBuilder, StoredOverrides, custom_backend, - custom_backend_with_rotations, importance_sampling, sim_neo, sim_neo_builder, sparse_stab, - state_vector, + custom_backend_from_factory, custom_backend_with_rotations, importance_sampling, sim_neo, + sim_neo_builder, sparse_stab, state_vector, }; #[cfg(feature = "engines-adapter")] pub use simulation::{PendingEngineBuilder, TypedProgram}; diff --git a/exp/pecos-neo/src/tool/simulation.rs b/exp/pecos-neo/src/tool/simulation.rs index bc6af5c7d..59fed84af 100644 --- a/exp/pecos-neo/src/tool/simulation.rs +++ b/exp/pecos-neo/src/tool/simulation.rs @@ -363,6 +363,20 @@ where } } +/// Create a custom backend from a `SimulatorFactory` implementation. +/// +/// Unlike [`custom_backend()`] which takes a closure, this accepts any type +/// implementing `SimulatorFactory` directly. Use this when the factory needs +/// configuration state (e.g., `StabMpsBackend` with bond dimension settings). +#[must_use] +pub fn custom_backend_from_factory( + factory: impl SimulatorFactory + 'static, +) -> CustomBackendBuilder { + CustomBackendBuilder { + factory: Box::new(factory), + } +} + /// Create a custom backend with rotation support from a factory closure. /// /// Like [`custom_backend()`], but enables rotation gates (T, RZ, etc.) for @@ -646,7 +660,7 @@ impl Default for SimConfig { /// /// let circuit = CommandBuilder::new().pz(&[0]).h(&[0]).mz(&[0]).build(); /// let results = sim_neo(circuit) -/// .orchestrator(importance_sampling() +/// .sampling(importance_sampling() /// .with_p1(0.001) /// .with_p2(0.01) /// .with_p_meas(0.001) @@ -721,10 +735,10 @@ impl ImportanceSamplingBuilder { self } - /// Build the orchestrator. + /// Build the sampling. #[must_use] - pub fn build(self) -> Orchestrator { - Orchestrator::ImportanceSampling { config: self } + pub fn build(self) -> Sampling { + Sampling::ImportanceSampling { config: self } } /// Get the single-qubit error rate. @@ -758,13 +772,13 @@ impl Default for ImportanceSamplingBuilder { } } -impl From for Orchestrator { +impl From for Sampling { fn from(builder: ImportanceSamplingBuilder) -> Self { builder.build() } } -/// Create an importance sampling orchestrator builder. +/// Create an importance sampling sampling builder. /// /// Importance sampling biases noise toward higher error rates to observe /// rare events more frequently, then reweights results for unbiased estimates. @@ -777,7 +791,7 @@ impl From for Orchestrator { /// /// let circuit = CommandBuilder::new().pz(&[0]).h(&[0]).mz(&[0]).build(); /// let results = sim_neo(circuit) -/// .orchestrator(importance_sampling() +/// .sampling(importance_sampling() /// .with_p1(0.001) /// .with_p2(0.01) /// .with_boost(10.0)) @@ -809,7 +823,7 @@ pub fn importance_sampling() -> ImportanceSamplingBuilder { /// using the Tool/Schedule/Plugin system. Use `.workers(n)` or `.auto_workers()` /// for parallel execution. #[derive(Debug, Clone)] -pub enum Orchestrator { +pub enum Sampling { /// Monte Carlo execution (sequential with 1 worker, parallel with >1). /// /// Each worker runs a batch of shots independently with deterministic seeding. @@ -830,29 +844,29 @@ pub enum Orchestrator { /// Configuration for importance sampling. config: ImportanceSamplingBuilder, }, + } -impl Default for Orchestrator { +impl Default for Sampling { fn default() -> Self { Self::MonteCarlo { workers: 1 } } } -impl Orchestrator { - /// Create a Monte Carlo orchestrator with specified workers. +impl Sampling { + /// Create a Monte Carlo sampling with specified workers. #[must_use] pub fn monte_carlo(workers: usize) -> Self { Self::MonteCarlo { workers } } - /// Create a Monte Carlo orchestrator with auto-detected worker count. + /// Create a Monte Carlo sampling with auto-detected worker count. #[must_use] pub fn monte_carlo_auto() -> Self { - let workers = std::thread::available_parallelism() - .map(std::num::NonZero::get) - .unwrap_or(1); + let workers = std::thread::available_parallelism().map_or(1, std::num::NonZero::get); Self::MonteCarlo { workers } } + } /// Accumulated simulation results. @@ -1287,7 +1301,7 @@ pub struct SimNeoBuilder { /// Simulation configuration (data). config: SimConfig, /// Orchestration strategy (data). - orchestrator: Orchestrator, + sampling: Sampling, /// Quantum backend configuration (data). quantum_backend: QuantumBackend, /// Explicit qubit count override (data). @@ -1311,7 +1325,7 @@ impl SimNeoBuilder { noise: None, definitions: None, config: SimConfig::default(), - orchestrator: Orchestrator::default(), + sampling: Sampling::default(), quantum_backend: QuantumBackend::default(), explicit_num_qubits: None, max_decomp_depth: None, @@ -1332,7 +1346,7 @@ impl SimNeoBuilder { noise: None, definitions: None, config: SimConfig::default(), - orchestrator: Orchestrator::default(), + sampling: Sampling::default(), quantum_backend: QuantumBackend::default(), explicit_num_qubits: None, max_decomp_depth: None, @@ -1354,7 +1368,7 @@ impl SimNeoBuilder { noise: None, definitions: None, config: SimConfig::default(), - orchestrator: Orchestrator::default(), + sampling: Sampling::default(), quantum_backend: QuantumBackend::default(), explicit_num_qubits: None, max_decomp_depth: None, @@ -1381,7 +1395,7 @@ impl SimNeoBuilder { noise: None, definitions: None, config: SimConfig::default(), - orchestrator: Orchestrator::default(), + sampling: Sampling::default(), quantum_backend: QuantumBackend::default(), explicit_num_qubits: None, max_decomp_depth: None, @@ -1618,9 +1632,9 @@ impl SimNeoBuilder { // Classical engines are stateful and cannot be parallelized across workers. // Static circuits can run in parallel since each worker gets its own simulator. if is_classical { - self.orchestrator = Orchestrator::MonteCarlo { workers: 1 }; + self.sampling = Sampling::MonteCarlo { workers: 1 }; } else { - self.orchestrator = Orchestrator::monte_carlo_auto(); + self.sampling = Sampling::monte_carlo_auto(); } self } @@ -1654,28 +1668,28 @@ impl SimNeoBuilder { /// # Example /// /// ```no_run - /// use pecos_neo::tool::{sim_neo, Orchestrator}; + /// use pecos_neo::tool::{sim_neo, Sampling}; /// use pecos_neo::prelude::*; /// /// let circuit = CommandBuilder::new().pz(&[0]).h(&[0]).mz(&[0]).build(); /// /// // Parallel Monte Carlo with 4 workers /// let results = sim_neo(circuit.clone()) - /// .orchestrator(Orchestrator::monte_carlo(4)) + /// .sampling(Sampling::monte_carlo(4)) /// .shots(1000) /// .build() /// .run(); /// /// // Auto-detect worker count /// let results = sim_neo(circuit) - /// .orchestrator(Orchestrator::monte_carlo_auto()) + /// .sampling(Sampling::monte_carlo_auto()) /// .shots(1000) /// .build() /// .run(); /// ``` #[must_use] - pub fn orchestrator(mut self, orchestrator: impl Into) -> Self { - self.orchestrator = orchestrator.into(); + pub fn sampling(mut self, sampling: impl Into) -> Self { + self.sampling = sampling.into(); self } @@ -1693,7 +1707,7 @@ impl SimNeoBuilder { /// backends are not supported. #[must_use] pub fn workers(mut self, workers: usize) -> Self { - self.orchestrator = Orchestrator::monte_carlo(workers); + self.sampling = Sampling::monte_carlo(workers); self } @@ -1702,7 +1716,7 @@ impl SimNeoBuilder { /// See [`workers()`](Self::workers) for requirements and panics. #[must_use] pub fn auto_workers(mut self) -> Self { - self.orchestrator = Orchestrator::monte_carlo_auto(); + self.sampling = Sampling::monte_carlo_auto(); self } @@ -2037,14 +2051,14 @@ impl SimNeoBuilder { .insert_resource(self.config) .insert_resource(QuantumBackendResource(self.quantum_backend)); - match &self.orchestrator { - Orchestrator::ImportanceSampling { config: is_config } => { + match &self.sampling { + Sampling::ImportanceSampling { config: is_config } => { tool = tool.add_plugin(&ImportanceSamplingSimPlugin { is_config: is_config.clone(), explicit_num_qubits: self.explicit_num_qubits, }); } - Orchestrator::MonteCarlo { .. } => { + Sampling::MonteCarlo { .. } => { tool = tool.add_plugin(&UnifiedSimulationPlugin { explicit_num_qubits: self.explicit_num_qubits, }); @@ -2078,7 +2092,7 @@ impl SimNeoBuilder { Simulation { tool, - orchestrator: self.orchestrator, + sampling: self.sampling, parallel_data, } } @@ -2387,7 +2401,7 @@ fn unified_simulation_post_shot(resources: &mut Resources) { /// Plugin for importance-sampling simulation. /// -/// Replaces [`UnifiedSimulationPlugin`] when the IS orchestrator is selected. +/// Replaces [`UnifiedSimulationPlugin`] when the IS sampling is selected. /// Uses [`ImportanceSamplingRunner`] for biased noise with weight tracking. struct ImportanceSamplingSimPlugin { is_config: ImportanceSamplingBuilder, @@ -2533,6 +2547,7 @@ fn is_sim_post_shot(resources: &mut Resources) { resources.get_mut::().shot_index += 1; } + // --- Simulation Handle --- /// Reusable simulation handle. @@ -2558,7 +2573,7 @@ fn is_sim_post_shot(resources: &mut Resources) { pub struct Simulation { tool: Tool, /// Orchestration strategy (stored as data). - orchestrator: Orchestrator, + sampling: Sampling, /// Data for parallel execution (if applicable). /// Stored separately from Tool to allow cloning for workers. parallel_data: Option, @@ -2612,7 +2627,7 @@ impl Simulation { /// Returns the simulation results. The simulation can be run again /// after reconfiguring with [`shots()`](Self::shots) or [`seed()`](Self::seed). /// - /// Execution strategy depends on the orchestrator: + /// Execution strategy depends on the sampling: /// - `MonteCarlo { workers: 1 }`: Runs shots via the Tool (default) /// - `MonteCarlo { workers: n }`: Parallelizes shots across n workers /// - `ImportanceSampling`: Runs via the Tool with `ImportanceSamplingSimPlugin` @@ -2623,8 +2638,8 @@ impl Simulation { let config = self.tool.resource::().clone(); // Dispatch based on orchestration strategy - match &self.orchestrator { - Orchestrator::MonteCarlo { workers } if *workers > 1 => { + match &self.sampling { + Sampling::MonteCarlo { workers } if *workers > 1 => { let data = self.parallel_data.as_ref().unwrap_or_else(|| { panic!( "Parallel Monte Carlo requires a static circuit \ @@ -3318,14 +3333,14 @@ mod tests { #[test] fn test_sim_neo_orchestrator_explicit() { - // Test explicit orchestrator configuration - use super::Orchestrator; + // Test explicit sampling configuration + use super::Sampling; let circuit = CommandBuilder::new().pz(&[0]).x(&[0]).mz(&[0]).build(); - // Use explicit Orchestrator enum + // Use explicit Sampling enum let results = sim_neo(circuit) - .orchestrator(Orchestrator::monte_carlo(2)) + .sampling(Sampling::monte_carlo(2)) .shots(20) .seed(42) .run(); @@ -3353,7 +3368,7 @@ mod tests { // Run with default (1 worker) let single_results = sim_neo(circuit.clone()).shots(50).seed(42).run(); - // Run with parallel Monte Carlo orchestrator (4 workers) + // Run with parallel Monte Carlo sampling (4 workers) let parallel_results = sim_neo(circuit).workers(4).shots(50).seed(42).run(); // Results should be identical @@ -3398,7 +3413,7 @@ mod tests { .seed(42) .run(); - // Run with parallel Monte Carlo orchestrator + // Run with parallel Monte Carlo sampling let parallel_results = sim_neo(circuit) .noise(noise_par) .workers(4) @@ -3587,7 +3602,7 @@ mod tests { } } - // --- Importance Sampling Orchestrator Tests --- + // --- Importance Sampling Sampling Tests --- #[test] fn test_sim_neo_importance_sampling_basic() { @@ -3601,7 +3616,7 @@ mod tests { .build(); let results = sim_neo(circuit) - .orchestrator( + .sampling( importance_sampling() .with_p1(0.01) .with_p2(0.02) @@ -3630,7 +3645,7 @@ mod tests { let circuit = CommandBuilder::new().pz(&[0]).h(&[0]).mz(&[0]).build(); let results = sim_neo(circuit) - .orchestrator( + .sampling( importance_sampling() .with_uniform_error(0.01) .with_boost(10.0), @@ -3657,7 +3672,7 @@ mod tests { // Run with importance sampling (boosting noise that doesn't affect this test) let results = sim_neo(circuit) - .orchestrator( + .sampling( importance_sampling() .with_uniform_error(0.001) .with_boost(100.0), @@ -3696,13 +3711,13 @@ mod tests { .with_boost(10.0); let results1 = sim_neo(circuit.clone()) - .orchestrator(is_builder.clone()) + .sampling(is_builder.clone()) .shots(20) .seed(42) .run(); let results2 = sim_neo(circuit) - .orchestrator(is_builder) + .sampling(is_builder) .shots(20) .seed(42) .run(); @@ -3747,7 +3762,7 @@ mod tests { .build(); let results = sim_neo(circuit) - .orchestrator( + .sampling( importance_sampling() .with_p1(0.001) .with_p2(0.01) @@ -3770,7 +3785,7 @@ mod tests { let circuit = CommandBuilder::new().pz(&[0]).h(&[0]).mz(&[0]).build(); let results = sim_neo(circuit) - .orchestrator( + .sampling( importance_sampling() .with_uniform_error(0.01) .with_boost(10.0), diff --git a/exp/pecos-stab-tn/Cargo.toml b/exp/pecos-stab-tn/Cargo.toml new file mode 100644 index 000000000..dad469731 --- /dev/null +++ b/exp/pecos-stab-tn/Cargo.toml @@ -0,0 +1,49 @@ +[package] +name = "pecos-stab-tn" +version.workspace = true +edition.workspace = true +readme.workspace = true +authors.workspace = true +homepage.workspace = true +repository.workspace = true +license.workspace = true +keywords.workspace = true +categories.workspace = true +description = "Experimental hybrid stabilizer + tensor network simulation methods (STN, MAST, CAMPS, etc.)." +publish = false + +[lib] +crate-type = ["rlib"] + +[dependencies] +pecos-core.workspace = true +pecos-quantum.workspace = true +pecos-random.workspace = true +pecos-simulators.workspace = true +nalgebra.workspace = true +num-complex.workspace = true +rayon = "1.10" +thiserror.workspace = true + +[dev-dependencies] +approx.workspace = true +paste.workspace = true + +[lints.clippy] +# Inherit workspace pedantic lint policy +suspicious = { level = "warn", priority = -1 } +complexity = { level = "warn", priority = -1 } +perf = { level = "warn", priority = -1 } +style = { level = "warn", priority = -1 } +pedantic = { level = "warn", priority = -1 } +cargo = { level = "warn", priority = -1 } +multiple-crate-versions = "allow" +similar-names = "allow" +many-single-char-names = "allow" +too-many-lines = "allow" +# Numeric casts in test/example code use small values (qubits <= 64, trial +# counts <= 10000) where the casts are exact. Library code avoids lossy casts. +cast_precision_loss = "allow" +cast_possible_truncation = "allow" +cast_possible_wrap = "allow" +cast_sign_loss = "allow" diff --git a/exp/pecos-stab-tn/docs/approach.md b/exp/pecos-stab-tn/docs/approach.md new file mode 100644 index 000000000..e82b71940 --- /dev/null +++ b/exp/pecos-stab-tn/docs/approach.md @@ -0,0 +1,3 @@ +# Moved to pecos-docs vault + +This document has been moved to `~/Repos/pecos-docs/design/stab-tn/approach.md`. diff --git a/exp/pecos-stab-tn/docs/future_work.md b/exp/pecos-stab-tn/docs/future_work.md new file mode 100644 index 000000000..f1c47453b --- /dev/null +++ b/exp/pecos-stab-tn/docs/future_work.md @@ -0,0 +1,3 @@ +# Moved to pecos-docs vault + +This document has been moved to `~/Repos/pecos-docs/design/stab-tn/future-work.md`. diff --git a/exp/pecos-stab-tn/docs/landscape.md b/exp/pecos-stab-tn/docs/landscape.md new file mode 100644 index 000000000..8361359f2 --- /dev/null +++ b/exp/pecos-stab-tn/docs/landscape.md @@ -0,0 +1,3 @@ +# Moved to pecos-docs vault + +This document has been moved to `~/Repos/pecos-docs/design/stab-tn/landscape.md`. diff --git a/exp/pecos-stab-tn/docs/literature_status.md b/exp/pecos-stab-tn/docs/literature_status.md new file mode 100644 index 000000000..8968ce8fb --- /dev/null +++ b/exp/pecos-stab-tn/docs/literature_status.md @@ -0,0 +1,3 @@ +# Moved to pecos-docs vault + +This document has been moved to `~/Repos/pecos-docs/design/stab-tn/literature-status.md`. diff --git a/exp/pecos-stab-tn/docs/ofd_plan.md b/exp/pecos-stab-tn/docs/ofd_plan.md new file mode 100644 index 000000000..ff9606fdd --- /dev/null +++ b/exp/pecos-stab-tn/docs/ofd_plan.md @@ -0,0 +1,3 @@ +# Moved to pecos-docs vault + +This document has been moved to `~/Repos/pecos-docs/design/stab-tn/ofd-plan.md`. diff --git a/exp/pecos-stab-tn/docs/priorities.md b/exp/pecos-stab-tn/docs/priorities.md new file mode 100644 index 000000000..6c0b00b78 --- /dev/null +++ b/exp/pecos-stab-tn/docs/priorities.md @@ -0,0 +1,3 @@ +# Moved to pecos-docs vault + +This document has been moved to `~/Repos/pecos-docs/design/stab-tn/priorities.md`. diff --git a/exp/pecos-stab-tn/docs/references.md b/exp/pecos-stab-tn/docs/references.md new file mode 100644 index 000000000..a16b0eb15 --- /dev/null +++ b/exp/pecos-stab-tn/docs/references.md @@ -0,0 +1,3 @@ +# Moved to pecos-docs vault + +This document has been moved to `~/Repos/pecos-docs/design/stab-tn/references.md`. diff --git a/exp/pecos-stab-tn/examples/disent_firing_rate.rs b/exp/pecos-stab-tn/examples/disent_firing_rate.rs new file mode 100644 index 000000000..295636938 --- /dev/null +++ b/exp/pecos-stab-tn/examples/disent_firing_rate.rs @@ -0,0 +1,439 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Benchmark disent firing rate across random fuzz circuits. +//! +//! Reports what fraction of non-Clifford RZ gates successfully avoid the +//! multi-site CNOT cascade path via: (a) single-site decomposition, +//! (b) Stabilizer branch (no bond-dim growth), or (c) multi-site disent +//! (one MPS op + tableau right-compose). +//! +//! The remaining fraction hits the std multi-site path which applies CNOTs +//! on the MPS -- the case OFD would replace. + +use pecos_core::{Angle64, QubitId}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable}; +use pecos_stab_tn::stab_mps::StabMps; +use pecos_stab_tn::stab_mps::compile::StabMpsCompile; +use pecos_stab_tn::stab_mps::mast::Mast; +use std::f64::consts::TAU; + +/// Same xorshift generator as fuzz tests. +fn next_rng(state: &mut u64) -> u64 { + *state ^= *state << 13; + *state ^= *state >> 7; + *state ^= *state << 17; + *state +} + +/// Distribution of gate types to sample. +#[derive(Clone, Copy)] +enum GateMix { + /// Full random: H/S/X/CX/CZ/T/RZ/RX with equal weights. + Random, + /// Clifford + T only (research target for MAST). + CliffT, +} + +fn fuzz_circuit(num_qubits: usize, num_gates: usize, seed: u64, mix: GateMix) -> StabMps { + let mut stn = StabMps::with_seed(num_qubits, seed); + // xorshift state 0 stays 0 forever — skip seed 0 by adding offset. + let mut rng_state = seed.wrapping_add(1); + + for _ in 0..num_gates { + let n_types: u64 = match mix { + GateMix::Random => 8, + GateMix::CliffT => 6, + }; + let gate_type = next_rng(&mut rng_state) % n_types; + let q0 = (next_rng(&mut rng_state) % num_qubits as u64) as usize; + let q1 = loop { + let q = (next_rng(&mut rng_state) % num_qubits as u64) as usize; + if q != q0 { + break q; + } + }; + match gate_type { + 0 => { + stn.h(&[QubitId(q0)]); + } + 1 => { + stn.sz(&[QubitId(q0)]); + } + 2 => { + stn.x(&[QubitId(q0)]); + } + 3 => { + stn.cx(&[(QubitId(q0), QubitId(q1))]); + } + 4 => { + stn.cz(&[(QubitId(q0), QubitId(q1))]); + } + 5 => { + let t = Angle64::QUARTER_TURN / 2u64; + stn.rz(t, &[QubitId(q0)]); + } + 6 => { + let ab = next_rng(&mut rng_state); + let a = Angle64::from_radians((ab % 1000) as f64 * 0.001 * TAU); + stn.rz(a, &[QubitId(q0)]); + } + _ => { + let ab = next_rng(&mut rng_state); + let a = Angle64::from_radians((ab % 1000) as f64 * 0.001 * TAU); + stn.rx(a, &[QubitId(q0)]); + } + } + } + stn +} + +/// Run scenario with optional auto-disentangle every N gates. +fn run_scenario_with_auto( + label: &str, + n_qubits: usize, + n_gates: usize, + n_seeds: u64, + mix: GateMix, + auto_disent_every: Option, +) { + let mut max_bond_sum = 0u64; + let mut gates_disent_total = 0u64; + for seed in 0..n_seeds { + let mut stn = pecos_stab_tn::stab_mps::StabMps::with_seed(n_qubits, seed); + let mut rng_state = seed.wrapping_add(1); + let mut gate_count = 0; + for _ in 0..n_gates { + let n_types: u64 = match mix { + GateMix::Random => 8, + GateMix::CliffT => 6, + }; + let gate_type = next_rng(&mut rng_state) % n_types; + let q0 = (next_rng(&mut rng_state) % n_qubits as u64) as usize; + let q1 = loop { + let q = (next_rng(&mut rng_state) % n_qubits as u64) as usize; + if q != q0 { + break q; + } + }; + match gate_type { + 0 => { + stn.h(&[QubitId(q0)]); + } + 1 => { + stn.sz(&[QubitId(q0)]); + } + 2 => { + stn.x(&[QubitId(q0)]); + } + 3 => { + stn.cx(&[(QubitId(q0), QubitId(q1))]); + } + 4 => { + stn.cz(&[(QubitId(q0), QubitId(q1))]); + } + 5 => { + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(q0)]); + } + 6 => { + let ab = next_rng(&mut rng_state); + stn.rz( + Angle64::from_radians((ab % 1000) as f64 * 0.001 * TAU), + &[QubitId(q0)], + ); + } + _ => { + let ab = next_rng(&mut rng_state); + stn.rx( + Angle64::from_radians((ab % 1000) as f64 * 0.001 * TAU), + &[QubitId(q0)], + ); + } + } + gate_count += 1; + if let Some(every) = auto_disent_every + && gate_count % every == 0 + { + gates_disent_total += stn.disentangle(2) as u64; + } + } + // Final disent sweep + if auto_disent_every.is_some() { + gates_disent_total += stn.disentangle(3) as u64; + } + max_bond_sum += stn.max_bond_dim() as u64; + } + let avg_bond = max_bond_sum as f64 / n_seeds as f64; + let avg_disent = gates_disent_total as f64 / n_seeds as f64; + println!( + "{label:<28} n={n_qubits} gates={n_gates} auto_every={auto_disent_every:?} | avg_bond={avg_bond:.2} avg_disent_gates={avg_disent:.1}", + ); +} + +fn run_scenario(label: &str, n_qubits: usize, n_gates: usize, n_seeds: u64, mix: GateMix) { + use std::io::Write; + let mut total = 0u64; + let mut single = 0u64; + let mut disent = 0u64; + let mut std_path = 0u64; + let mut stabilizer = 0u64; + let mut max_bond_sum = 0u64; + let mut theoretical_bond_sum = 0u64; + let mut ofd_in_span = 0u64; + let mut ofd_wins = 0u64; // in_span gates heuristic sent through std path + + for seed in 0..n_seeds { + let stn = fuzz_circuit(n_qubits, n_gates, seed, mix); + theoretical_bond_sum += stn.gf2_matrix().theoretical_min_bond_dim() as u64; + ofd_in_span += stn.stats.ofd_in_span; + ofd_wins += stn.stats.ofd_in_span_std; + let s = stn.stats; + total += s.total_nonclifford; + single += s.single_site; + disent += s.multi_disent; + std_path += s.multi_std; + stabilizer += s.stabilizer; + max_bond_sum += stn.max_bond_dim() as u64; + } + + let pct = |x: u64| { + if total == 0 { + 0.0 + } else { + 100.0 * x as f64 / total as f64 + } + }; + let avg_bond = max_bond_sum as f64 / n_seeds as f64; + let avg_theo = theoretical_bond_sum as f64 / n_seeds as f64; + println!( + "{label:<24} n={n_qubits} gates={n_gates} | total={total} \ + heur: stab={:.0}% single={:.0}% disent={:.0}% std={:.0}% | \ + OFD in_span={:.0}% | OFD wins (in_span but heur-std) ={ofd_wins}/{} ({:.0}%) | \ + bond={avg_bond:.2}/{avg_theo:.2}", + pct(stabilizer), + pct(single), + pct(disent), + pct(std_path), + pct(ofd_in_span), + std_path, + if std_path == 0 { + 0.0 + } else { + 100.0 * ofd_wins as f64 / std_path as f64 + }, + ); + let _ = std::io::stdout().flush(); +} + +fn main() { + println!("Disent firing rate benchmark. Runs random fuzz circuits and reports"); + println!("what fraction of non-Clifford RZs take each code path."); + println!(); + println!(" stab = Stabilizer branch (Z_q already a stabilizer product: no MPS site ops)"); + println!(" single = single-site decomposition (trivial 1-qubit gate on MPS)"); + println!(" disent = multi-site disent fires (1-qubit MPS op + tableau right-compose)"); + println!(" std = multi-site CNOT cascade on MPS (OFD target to replace)"); + println!(); + + // Random gate mix: Cliffords + rotations + T. + println!("=== Random gate mix (H/S/X/CX/CZ/T/RZ/RX) ==="); + run_scenario("2q shallow", 2, 10, 100, GateMix::Random); + run_scenario("2q medium", 2, 20, 100, GateMix::Random); + run_scenario("2q deep", 2, 50, 50, GateMix::Random); + run_scenario("3q shallow", 3, 10, 50, GateMix::Random); + run_scenario("3q medium", 3, 20, 30, GateMix::Random); + run_scenario("4q shallow", 4, 10, 30, GateMix::Random); + run_scenario("4q medium", 4, 20, 20, GateMix::Random); + + // T-heavy: research target for MAST / Clifford+T simulation. + println!("\n=== Clifford + T only (H/S/X/CX/CZ/T) ==="); + run_scenario("2q T 10g", 2, 10, 100, GateMix::CliffT); + run_scenario("2q T 30g", 2, 30, 50, GateMix::CliffT); + run_scenario("3q T 15g", 3, 15, 50, GateMix::CliffT); + run_scenario("3q T 30g", 3, 30, 30, GateMix::CliffT); + run_scenario("4q T 20g", 4, 20, 20, GateMix::CliffT); + run_scenario("5q T 20g", 5, 20, 10, GateMix::CliffT); + run_scenario("8q T 30g", 8, 30, 5, GateMix::CliffT); + run_scenario("10q T 40g", 10, 40, 3, GateMix::CliffT); + run_scenario("15q T 50g", 15, 50, 2, GateMix::CliffT); + + // Test auto-heuristic-disentangle: compare to baseline on 2q deep (bond 2) + // where std path fires heavily. + // Pre-analysis with StabMpsCompile: same circuit, no MPS cost. Verifies + // that the compile-only pass gives matching OFD predictions. + println!("\n=== StabMpsCompile pre-analysis (no MPS cost) ==="); + bench_compile("5q T 20g", 5, 20, 50, GateMix::CliffT); + bench_compile("10q T 30g", 10, 30, 20, GateMix::CliffT); + bench_compile("20q T 50g", 20, 50, 10, GateMix::CliffT); + bench_compile("50q T 100g", 50, 100, 5, GateMix::CliffT); + bench_compile("100q T 200g", 100, 200, 2, GateMix::CliffT); + + println!("\n=== Auto heuristic disentangle (on 2q deep) ==="); + run_scenario_with_auto("baseline (no auto)", 2, 50, 20, GateMix::Random, None); + run_scenario_with_auto("auto every 5 gates", 2, 50, 20, GateMix::Random, Some(5)); + run_scenario_with_auto("auto every 10 gates", 2, 50, 20, GateMix::Random, Some(10)); + run_scenario_with_auto("auto every 20 gates", 2, 50, 20, GateMix::Random, Some(20)); + + println!("\n=== Auto heuristic disentangle (on 3q T 30g) ==="); + run_scenario_with_auto("baseline (no auto)", 3, 30, 20, GateMix::CliffT, None); + run_scenario_with_auto("auto every 5 gates", 3, 30, 20, GateMix::CliffT, Some(5)); + run_scenario_with_auto("auto every 10 gates", 3, 30, 20, GateMix::CliffT, Some(10)); + + // MAST: magic-state injection scheme. Targets 20-200 qubits with bond ~1. + println!("\n=== MAST (Clifford+T, deferred ancilla projection) ==="); + run_mast_scenario("10q T 10", 10, 10, 10); + run_mast_scenario("10q T 50", 10, 50, 5); + run_mast_scenario("20q T 20", 20, 20, 5); + run_mast_scenario("20q T 100", 20, 100, 3); + run_mast_scenario("50q T 20", 50, 20, 3); + run_mast_scenario("50q T 100", 50, 100, 1); + run_mast_scenario("100q T 30", 100, 30, 2); + run_mast_scenario("100q T 100", 100, 100, 1); +} + +/// Benchmark `StabMpsCompile` on a fuzz circuit: reports timing and nullity. +fn bench_compile(label: &str, n_qubits: usize, n_gates: usize, n_seeds: u64, mix: GateMix) { + let mut total_nullity = 0usize; + let mut total_absorbed = 0u64; + let mut total_grown = 0u64; + let start = std::time::Instant::now(); + for seed in 0..n_seeds { + let mut c = StabMpsCompile::new(n_qubits); + let mut rng_state = seed.wrapping_add(1); + for _ in 0..n_gates { + let n_types: u64 = match mix { + GateMix::Random => 8, + GateMix::CliffT => 6, + }; + let gate_type = next_rng(&mut rng_state) % n_types; + let q0 = (next_rng(&mut rng_state) % n_qubits as u64) as usize; + let q1 = loop { + let q = (next_rng(&mut rng_state) % n_qubits as u64) as usize; + if q != q0 { + break q; + } + }; + match gate_type { + 0 => { + c.h(&[QubitId(q0)]); + } + 1 => { + c.sz(&[QubitId(q0)]); + } + 2 => { + c.x(&[QubitId(q0)]); + } + 3 => { + c.cx(&[(QubitId(q0), QubitId(q1))]); + } + 4 => { + c.cz(&[(QubitId(q0), QubitId(q1))]); + } + 5 => { + c.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(q0)]); + } + 6 => { + let ab = next_rng(&mut rng_state); + c.rz( + Angle64::from_radians((ab % 1000) as f64 * 0.001 * TAU), + &[QubitId(q0)], + ); + } + _ => { + let ab = next_rng(&mut rng_state); + c.rx( + Angle64::from_radians((ab % 1000) as f64 * 0.001 * TAU), + &[QubitId(q0)], + ); + } + } + } + total_nullity += c.nullity(); + total_absorbed += c.absorbed(); + total_grown += c.grown(); + } + let elapsed_ms = start.elapsed().as_secs_f64() * 1000.0; + let avg_nullity = total_nullity as f64 / n_seeds as f64; + let avg_absorbed = total_absorbed as f64 / n_seeds as f64; + let avg_grown = total_grown as f64 / n_seeds as f64; + println!( + "{label:<20} n={n_qubits} g={n_gates} | absorbed={avg_absorbed:.1} grown={avg_grown:.1} nullity={avg_nullity:.1} bound=2^{avg_nullity:.1} | elapsed={elapsed_ms:.1}ms ({n_seeds} seeds)", + ); +} + +fn run_mast_scenario(label: &str, n_data: usize, n_t: usize, n_seeds: u64) { + let mut total = 0u64; + let mut single = 0u64; + let mut disent = 0u64; + let mut std_path = 0u64; + let mut stabilizer = 0u64; + let mut max_bond_sum = 0u64; + + for seed in 0..n_seeds { + let mut mast = Mast::with_seed(n_data, n_t, seed); + let mut rng_state = seed.wrapping_add(1); + // Scatter H/CX and T gates so ancillas get diverse inputs. + for _ in 0..n_t { + // Random Clifford layer + for _ in 0..3 { + let gt = next_rng(&mut rng_state) % 3; + let q0 = (next_rng(&mut rng_state) % n_data as u64) as usize; + let q1 = loop { + let q = (next_rng(&mut rng_state) % n_data as u64) as usize; + if q != q0 { + break q; + } + }; + match gt { + 0 => { + mast.h(&[QubitId(q0)]); + } + 1 => { + mast.sz(&[QubitId(q0)]); + } + _ => { + mast.cx(&[(QubitId(q0), QubitId(q1))]); + } + } + } + // T gate on random qubit + let tq = (next_rng(&mut rng_state) % n_data as u64) as usize; + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(tq)]); + } + mast.project_all(); + + let s = mast.stats; + total += s.total_nonclifford; + single += s.single_site; + disent += s.multi_disent; + std_path += s.multi_std; + stabilizer += s.stabilizer; + max_bond_sum += mast.max_bond_dim() as u64; + } + + let pct = |x: u64| { + if total == 0 { + 0.0 + } else { + 100.0 * x as f64 / total as f64 + } + }; + let avg_bond = max_bond_sum as f64 / n_seeds as f64; + println!( + "{label:<24} n={n_data} T={n_t} seeds={n_seeds} | \ + total={total} stab={stabilizer} ({:.1}%) single={single} ({:.1}%) disent={disent} ({:.1}%) std={std_path} ({:.1}%) | avg_max_bond={avg_bond:.2}", + pct(stabilizer), + pct(single), + pct(disent), + pct(std_path), + ); +} diff --git a/exp/pecos-stab-tn/examples/qec_bench.rs b/exp/pecos-stab-tn/examples/qec_bench.rs new file mode 100644 index 000000000..8c04730bd --- /dev/null +++ b/exp/pecos-stab-tn/examples/qec_bench.rs @@ -0,0 +1,285 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! QEC-like benchmark: syndrome-extraction rounds with small RZ noise. +//! +//! Structure per round: +//! 1. CX ladder entangles each data qubit with its ancilla (syndrome extraction). +//! 2. Small-angle RZ noise on every data qubit (decoherence model). +//! 3. CX ladder in reverse. +//! 4. Ancilla measurements (in Z basis). +//! 5. Ancilla resets (prep |0>). +//! +//! Compares wall time + max bond dim across builder knob combinations: +//! - default (eager measure, no adaptive truncation) +//! - `lazy_measure` +//! - `max_truncation_error` +//! - both +//! +//! Usage: `cargo run --release --example qec_bench`. + +use pecos_core::{Angle64, QubitId}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable}; +use pecos_stab_tn::stab_mps::StabMps; +use pecos_stab_tn::stab_mps::mast::Mast; +use std::time::Instant; + +struct BenchConfig { + num_data: usize, + num_rounds: usize, + noise_angle: Angle64, + lazy: bool, + max_trunc: Option, + merge_rz: bool, + max_bond: usize, + seed: u64, +} + +fn build_and_run(cfg: &BenchConfig) -> (f64, usize, u64) { + let BenchConfig { + num_data, + num_rounds, + noise_angle, + lazy, + max_trunc, + merge_rz, + max_bond, + seed, + } = *cfg; + // Layout: data qubits [0..num_data), ancilla qubits [num_data..2*num_data). + let n = num_data * 2; + let mut builder = StabMps::builder(n) + .seed(seed) + .max_bond_dim(max_bond) + .lazy_measure(lazy) + .merge_rz(merge_rz); + if let Some(e) = max_trunc { + builder = builder.max_truncation_error(e); + } + let mut stn = builder.build(); + + let start = Instant::now(); + let mut outcome_parity: u64 = 0; + + // Simple xorshift for reproducible pseudo-random gate choices. + let mut rng_state = seed.wrapping_mul(0x9E37_79B9_7F4A_7C15).wrapping_add(1); + let next_u64 = |s: &mut u64| -> u64 { + *s ^= *s << 13; + *s ^= *s >> 7; + *s ^= *s << 17; + *s + }; + + // Initial H on all data to spread into superposition. + for i in 0..num_data { + stn.h(&[QubitId(i)]); + } + + for _round in 0..num_rounds { + // 1. Long-range CX cascade between random data pairs (mixes entanglement). + for _ in 0..num_data { + let a = (next_u64(&mut rng_state) as usize) % num_data; + let b = (next_u64(&mut rng_state) as usize) % num_data; + if a != b { + stn.cx(&[(QubitId(a), QubitId(b))]); + } + } + // 2. T gates (non-Clifford) on random data qubits. + for _ in 0..num_data { + let q = (next_u64(&mut rng_state) as usize) % num_data; + stn.rz(noise_angle, &[QubitId(q)]); + } + // 3. Entangle each data with its ancilla (syndrome extraction). + for i in 0..num_data { + stn.cx(&[(QubitId(i), QubitId(num_data + i))]); + } + // 4. Ancilla measurements (Z-basis). + for i in 0..num_data { + let outcome = stn.mz(&[QubitId(num_data + i)])[0].outcome; + if outcome { + outcome_parity ^= 1 << (i % 64); + } + } + } + let elapsed = start.elapsed().as_secs_f64(); + let max_bond_dim = stn.max_bond_dim(); + (elapsed, max_bond_dim, outcome_parity) +} + +/// Ion-trap-memory-noise scenario: many small-angle RZs per round on +/// every data qubit (modeling per-step dephasing). RZ batching should +/// merge these consecutive same-qubit RZs into one non-Clifford op. +fn ion_trap_memory_scenario( + num_data: usize, + num_rounds: usize, + noise_per_round: usize, + noise_angle: Angle64, + merge_rz: bool, + seed: u64, +) -> (f64, usize) { + let mut stn = StabMps::builder(num_data) + .seed(seed) + .merge_rz(merge_rz) + .build(); + + // Initial superposition. + for q in 0..num_data { + stn.h(&[QubitId(q)]); + } + + let start = Instant::now(); + for _round in 0..num_rounds { + // Many small-angle RZ noise per qubit (memory error each timestep). + for _ in 0..noise_per_round { + for q in 0..num_data { + stn.rz(noise_angle, &[QubitId(q)]); + } + } + // One Clifford layer per round (e.g., a syndrome-extraction-like CX). + for q in 0..num_data - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + } + stn.flush(); + let elapsed = start.elapsed().as_secs_f64(); + let bond = stn.max_bond_dim(); + (elapsed, bond) +} + +/// MAST-style: T-injection using ancilla pattern, final measurement. +fn mast_scenario(num_qubits: usize, num_t_gates: usize, lazy: bool, seed: u64) -> (f64, usize) { + let mut mast = Mast::with_seed(num_qubits, num_t_gates, seed).with_lazy_measure(lazy); + let t = Angle64::QUARTER_TURN / 2u64; + + let start = Instant::now(); + + // Random Clifford + T circuit + measurement. + for q in 0..num_qubits { + mast.h(&[QubitId(q)]); + } + for q in 0..num_qubits - 1 { + mast.cx(&[(QubitId(q), QubitId(q + 1))]); + } + let mut rng_state = 30000u64 + seed; + for _ in 0..num_t_gates { + rng_state ^= rng_state << 13; + rng_state ^= rng_state >> 7; + rng_state ^= rng_state << 17; + let q = (rng_state % num_qubits as u64) as usize; + mast.rz(t, &[QubitId(q)]); + } + for q in (0..num_qubits - 1).rev() { + mast.cx(&[(QubitId(q + 1), QubitId(q))]); + } + let _ = mast.mz(&[QubitId(0)]); + + let elapsed = start.elapsed().as_secs_f64(); + let bond = mast.mps().max_bond_dim(); + (elapsed, bond) +} + +fn main() { + // Magic-state-distillation-like: T gates per round (non-Clifford-heavy). + let t_angle = Angle64::QUARTER_TURN / 2u64; // T = RZ(π/4) + let num_data = 8; + let num_rounds = 20; + let max_bond = 64; + let seed = 42; + + println!( + "QEC-like bench: {num_data} data qubits, {num_rounds} rounds, T-gate per data per round" + ); + let _ = t_angle; + println!("{:-<90}", ""); + println!( + "{:<40} {:>12} {:>12} {:>20}", + "config", "time (s)", "max bond", "outcome parity" + ); + println!("{:-<90}", ""); + + let configs: &[(&str, bool, Option, bool)] = &[ + ("default", false, None, false), + ("lazy_measure", true, None, false), + ("max_truncation_error=1e-8", false, Some(1e-8), false), + ("merge_rz", false, None, true), + ( + "merge_rz + max_truncation_error=1e-8", + false, + Some(1e-8), + true, + ), + ("for_sparse_t()", false, Some(1e-8), true), + ]; + + for &(name, lazy, trunc, merge) in configs { + let (t, bond, parity) = build_and_run(&BenchConfig { + num_data, + num_rounds, + noise_angle: t_angle, + lazy, + max_trunc: trunc, + merge_rz: merge, + max_bond, + seed, + }); + println!("{name:<40} {t:>12.4} {bond:>12} {parity:>20x}"); + } + + println!("{:-<90}", ""); + println!( + "\nNote: outcome parities differ between lazy/eager because the RNG is consumed in\n different sequences (not a correctness issue — both give the right distribution)." + ); + + // ------------------------------------------------------------------------- + // MAST-style scenario: where lazy_measure actually helps. + // ------------------------------------------------------------------------- + println!(); + println!("MAST-like scenario: deep random Clifford+T measured via ancilla injection"); + println!("{:-<70}", ""); + println!("{:<30} {:>12} {:>12}", "config", "time (s)", "max bond"); + println!("{:-<70}", ""); + + let n_q = 8; + let n_t = 8; + let num_trials = 20; + for (name, lazy) in [("eager", false), ("lazy", true)] { + let mut total_time = 0.0; + let mut total_bond = 0usize; + for trial in 0..num_trials { + let (t, b) = mast_scenario(n_q, n_t, lazy, 20000 + trial as u64); + total_time += t; + total_bond += b; + } + println!( + "{name:<30} {:>12.4} {:>12.1}", + total_time / f64::from(num_trials), + total_bond as f64 / f64::from(num_trials) + ); + } + println!("{:-<70}", ""); + + // ------------------------------------------------------------------------- + // Ion-trap memory noise scenario: where merge_rz actually helps. + // ------------------------------------------------------------------------- + println!(); + println!("Ion-trap memory noise: many small RZs per qubit each round"); + println!("(6 data qubits, 10 rounds, 50 noise RZs/qubit/round, θ=0.01 rad)"); + println!("{:-<70}", ""); + println!("{:<30} {:>12} {:>12}", "config", "time (s)", "max bond"); + println!("{:-<70}", ""); + let small_angle = Angle64::from_radians(0.01); + for (name, merge) in [("default", false), ("merge_rz", true)] { + let (t, b) = ion_trap_memory_scenario(6, 10, 50, small_angle, merge, 42); + println!("{name:<30} {t:>12.4} {b:>12}"); + } + println!("{:-<70}", ""); +} diff --git a/exp/pecos-stab-tn/examples/qec_tutorial.rs b/exp/pecos-stab-tn/examples/qec_tutorial.rs new file mode 100644 index 000000000..0a762cff4 --- /dev/null +++ b/exp/pecos-stab-tn/examples/qec_tutorial.rs @@ -0,0 +1,231 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! # QEC tutorial — the STN workflow end-to-end +//! +//! Run with `cargo run --release --example qec_tutorial`. +//! +//! This example walks through a typical quantum-error-correction +//! simulation using `pecos-stab-tn`. Each section maps to one feature +//! of the API; read top-to-bottom to understand how the pieces fit. +//! +//! Contents: +//! 1. Choosing a builder preset for QEC workloads. +//! 2. Defining a stabilizer code (3-qubit bit-flip). +//! 3. Noiseless syndrome extraction and ancilla reuse. +//! 4. Pauli-noise sampling via the `pauli_frame`. +//! 5. Many-round simulation with mid-circuit resets. +//! 6. Interpreting the results. + +use pecos_core::{Angle64, QubitId}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable}; +use pecos_stab_tn::stab_mps::{PauliKind, StabMps}; +use std::time::Instant; + +fn main() { + println!("============================================================="); + println!(" STN QEC tutorial"); + println!("=============================================================\n"); + + // ------------------------------------------------------------------ + // 1. Builder + preset + // ------------------------------------------------------------------ + // + // `StabMps::builder(n).for_sparse_t().build()` sets: + // - max_bond_dim = 128 (enough for syndrome rounds without truncation) + // - max_truncation_error = 1e-8 (very tight) + // - merge_rz = true (batch same-qubit RZ noise) + // + // For ion-trap-memory-noise or T-heavy workloads this is the right + // default. You can layer `pauli_frame_tracking(true)` on top for + // fast Pauli-noise injection. + // + // 3 data + 2 ancillas = 5 qubits total. + + let num_data = 3; + let num_ancillas = 2; // one per stabilizer generator + let n = num_data + num_ancillas; + let ancilla_base = num_data; + + let mut stn = StabMps::builder(n) + .seed(42) + .for_sparse_t() + .pauli_frame_tracking(true) + .build(); + + println!("Step 1: built StabMps with for_sparse_t() preset + pauli_frame_tracking"); + println!(" data qubits : 0..{num_data}"); + println!(" ancillas : {num_data}..{n}"); + println!(); + + // ------------------------------------------------------------------ + // 2. Define the code + // ------------------------------------------------------------------ + // + // Each stabilizer generator is a Vec<(qubit_index, PauliKind)>. + // For the 3-qubit bit-flip code: Z_0 Z_1 and Z_1 Z_2. + // + // `extract_syndromes` handles any Pauli generator — mix X/Y/Z freely. + + let stabilizers: Vec> = vec![ + vec![(0, PauliKind::Z), (1, PauliKind::Z)], + vec![(1, PauliKind::Z), (2, PauliKind::Z)], + ]; + let ancilla_qubits: Vec = (ancilla_base..ancilla_base + num_ancillas) + .map(QubitId) + .collect(); + + println!("Step 2: defined 3-qubit bit-flip code stabilizers"); + for (i, s) in stabilizers.iter().enumerate() { + println!(" g{i}: {s:?}"); + } + println!(); + + // ------------------------------------------------------------------ + // 3. Noiseless syndrome extraction + // ------------------------------------------------------------------ + // + // `extract_syndromes(generators, ancilla_qubits)`: + // 1. For each generator, prep_plus (|+⟩) the ancilla. + // 2. Apply controlled-P with ancilla as control. + // 3. H + measure ancilla → syndrome bit. + // 4. reset_qubit(ancilla) so it's ready for the next round. + // + // On the codespace, syndrome must be all-zero. + + // Data state starts at |000⟩ — already in the codespace for bit-flip. + let syndrome = stn.extract_syndromes(&stabilizers, &ancilla_qubits); + println!("Step 3: noiseless syndrome extraction"); + println!(" syndrome = {syndrome:?} (expected all-false)"); + assert!(syndrome.iter().all(|&b| !b)); + println!(); + + // ------------------------------------------------------------------ + // 4. Inject a single X error via the Pauli frame + // ------------------------------------------------------------------ + // + // With pauli_frame_tracking(true), `inject_x_in_frame` is O(1) — + // it toggles a classical bit rather than applying X to the state. + // The bit propagates through Cliffords and flips measurement + // outcomes at read time. + // + // For bulk injection, use `inject_paulis_in_frame(&[(q, Pauli), ...])`. + + println!("Step 4: inject X_0 error and re-extract syndrome"); + stn.inject_x_in_frame(QubitId(0)); + let syndrome = stn.extract_syndromes(&stabilizers, &ancilla_qubits); + println!(" syndrome = {syndrome:?} (expected [true, false]: X_0 triggers Z_0Z_1 only)"); + println!(); + + // ------------------------------------------------------------------ + // 5. Many rounds with random noise + // ------------------------------------------------------------------ + // + // Apply depolarizing noise to each data qubit each round, then + // extract. Frame tracking + merge_rz makes this fast. We count + // how often the syndrome is non-zero as a function of noise rate. + + println!("Step 5: many-round detection rate vs depolarizing rate"); + let num_rounds = 5000; + for &p in &[0.001_f64, 0.005, 0.01, 0.02, 0.05] { + let mut non_zero_syndromes = 0u32; + let mut stn = StabMps::builder(n) + .seed(100 + (p * 1e6) as u64) + .for_sparse_t() + .pauli_frame_tracking(true) + .build(); + + let start = Instant::now(); + for _round in 0..num_rounds { + // Per-round depolarizing on each data qubit. + for q in 0..num_data { + stn.apply_depolarizing(QubitId(q), p); + } + let s = stn.extract_syndromes(&stabilizers, &ancilla_qubits); + if s.iter().any(|&b| b) { + non_zero_syndromes += 1; + } + } + let elapsed = start.elapsed().as_secs_f64(); + let rate = f64::from(non_zero_syndromes) / f64::from(num_rounds); + println!( + " p={p:.3}: detection rate = {rate:.3} ({num_rounds} rounds in {elapsed:.2}s = {:.0} rounds/s)", + f64::from(num_rounds) / elapsed + ); + } + println!(); + + // ------------------------------------------------------------------ + // 6. Ion-trap-style RZ memory noise + // ------------------------------------------------------------------ + // + // Every "gate timestep" each idle qubit picks up a small rz(θ). + // merge_rz accumulates these until some gate or measurement forces + // a flush. Scales well — 25-42× speedup over the eager path. + + println!("Step 6: ion-trap memory noise scenario"); + let num_rounds_ion = 50; + let steps_per_round = 20; + let theta = Angle64::from_radians(0.005); + + let mut stn = StabMps::builder(n) + .seed(77) + .for_sparse_t() + .pauli_frame_tracking(true) + .build(); + let start = Instant::now(); + for _round in 0..num_rounds_ion { + for _step in 0..steps_per_round { + // Pass all data qubits in a single slice call — the rz + // method accumulates into pending_rz[q] for each q at O(1). + let data: Vec = (0..num_data).map(QubitId).collect(); + stn.rz(theta, &data); + } + stn.extract_syndromes(&stabilizers, &ancilla_qubits); + } + let elapsed = start.elapsed().as_secs_f64(); + println!( + " {num_rounds_ion} rounds × {steps_per_round} idle steps each, θ={theta:?}: {elapsed:.3}s" + ); + println!(); + + // ------------------------------------------------------------------ + // 7. Flush the frame before reading exact state + // ------------------------------------------------------------------ + // + // If you want exact state_vector/amplitude readouts (including + // complex phase from Y injections), call `flush_pauli_frame_to_state` + // first. The decomposition-based flush gives EXACT amplitudes even + // on Clifford-evolved states — no ±1 residual. + + let mut stn = StabMps::builder(2) + .seed(1) + .pauli_frame_tracking(true) + .build(); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.inject_y_in_frame(QubitId(0)); + stn.flush_pauli_frame_to_state(); + let sv = stn.state_vector(); + println!("Step 7: Y_0 on a Bell state, exact amplitudes after flush"); + for (i, a) in sv.iter().enumerate() { + println!(" sv[{i}] = {a:.4}"); + } + + println!("\nTutorial done. Key API summary:"); + println!(" - StabMps::builder(n).for_sparse_t().pauli_frame_tracking(true).build()"); + println!(" - extract_syndromes(generators, ancillas)"); + println!(" - reset_qubit(q), pz(q), px(q)"); + println!(" - inject_{{x,y,z}}_in_frame(q), inject_paulis_in_frame(&[...])"); + println!(" - apply_depolarizing(q, p), apply_depolarizing_all(&qs, p)"); + println!(" - flush_pauli_frame_to_state(): exact state_vector after Y frames"); +} diff --git a/exp/pecos-stab-tn/examples/rz_noise_scale.rs b/exp/pecos-stab-tn/examples/rz_noise_scale.rs new file mode 100644 index 000000000..329aea632 --- /dev/null +++ b/exp/pecos-stab-tn/examples/rz_noise_scale.rs @@ -0,0 +1,139 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Probe whether there's value in a dedicated batched-RZ-round API beyond +//! the existing `merge_rz` path. Two comparisons: +//! +//! A. Per-qubit loop vs single `rz(theta, &all_qubits)` slice call. +//! Pure Rust-call overhead of the noise-injection loop. +//! B. `merge_rz` on/off at scale, plus the effect of frame tracking for +//! the measurement-phase dominated regime. + +use pecos_core::{Angle64, QubitId}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable}; +use pecos_stab_tn::stab_mps::StabMps; +use std::time::Instant; + +fn ion_trap_per_qubit_loop( + n: usize, + rounds: usize, + noise_per_round: usize, + theta: Angle64, + merge: bool, + seed: u64, +) -> (f64, usize) { + let mut stn = StabMps::builder(n).seed(seed).merge_rz(merge).build(); + for q in 0..n { + stn.h(&[QubitId(q)]); + } + let start = Instant::now(); + for _round in 0..rounds { + for _ in 0..noise_per_round { + for q in 0..n { + stn.rz(theta, &[QubitId(q)]); + } + } + for q in 0..n - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + } + stn.flush(); + (start.elapsed().as_secs_f64(), stn.max_bond_dim()) +} + +fn ion_trap_slice_call( + n: usize, + rounds: usize, + noise_per_round: usize, + theta: Angle64, + merge: bool, + seed: u64, +) -> (f64, usize) { + let mut stn = StabMps::builder(n).seed(seed).merge_rz(merge).build(); + for q in 0..n { + stn.h(&[QubitId(q)]); + } + let qubits: Vec = (0..n).map(QubitId).collect(); + let start = Instant::now(); + for _round in 0..rounds { + for _ in 0..noise_per_round { + stn.rz(theta, &qubits); + } + for q in 0..n - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + } + stn.flush(); + (start.elapsed().as_secs_f64(), stn.max_bond_dim()) +} + +fn main() { + let theta = Angle64::from_radians(0.01); + + println!("Ion-trap memory noise — scaling + per-qubit-loop vs slice-call"); + println!("{:-<80}", ""); + println!( + "{:<30} {:>10} {:>12} {:>12}", + "config", "time (s)", "max bond", "rz calls" + ); + + // small + medium: compare merge_rz on/off. + for &(n, rounds, noise) in &[(12, 10, 20), (12, 20, 30)] { + let total_rz = rounds * noise * n; + println!("\n-- n={n}, rounds={rounds}, noise/round={noise} ({total_rz} rz calls)"); + let (t_off_loop, b_off) = ion_trap_per_qubit_loop(n, rounds, noise, theta, false, 42); + println!( + " {:<28} {:>10.4} {:>12}", + "merge_rz=OFF (loop)", t_off_loop, b_off + ); + let (t_on_loop, b_on) = ion_trap_per_qubit_loop(n, rounds, noise, theta, true, 42); + println!( + " {:<28} {:>10.4} {:>12} speedup {:.1}x", + "merge_rz=ON (loop)", + t_on_loop, + b_on, + t_off_loop / t_on_loop + ); + let (t_on_slice, b_on2) = ion_trap_slice_call(n, rounds, noise, theta, true, 42); + println!( + " {:<28} {:>10.4} {:>12} vs loop {:.2}x", + "merge_rz=ON (slice)", + t_on_slice, + b_on2, + t_on_loop / t_on_slice + ); + } + + // Medium-scale merge_rz=ON only (OFF is hours at these sizes). + { + let &(n, rounds, noise) = &(16, 20, 30); + let total_rz = rounds * noise * n; + println!( + "\n-- n={n}, rounds={rounds}, noise/round={noise} ({total_rz} rz calls, merge_rz=ON)" + ); + let (t_on_loop, b_on) = ion_trap_per_qubit_loop(n, rounds, noise, theta, true, 42); + println!(" {:<28} {:>10.4} {:>12}", "loop", t_on_loop, b_on); + let (t_on_slice, b_on2) = ion_trap_slice_call(n, rounds, noise, theta, true, 42); + println!( + " {:<28} {:>10.4} {:>12} vs loop {:.2}x", + "slice", + t_on_slice, + b_on2, + t_on_loop / t_on_slice + ); + } + + println!("\n{:-<80}", ""); + println!("Conclusion: merge_rz gives the dominant speedup. Passing all qubits in one"); + println!("slice call vs looping per-qubit makes no significant difference — the"); + println!("pending_rz accumulator is the hot path and already O(1) per rz invocation."); +} diff --git a/exp/pecos-stab-tn/examples/steane_code_demo.rs b/exp/pecos-stab-tn/examples/steane_code_demo.rs new file mode 100644 index 000000000..bc7ad0501 --- /dev/null +++ b/exp/pecos-stab-tn/examples/steane_code_demo.rs @@ -0,0 +1,365 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! End-to-end QEC code demo using STN. +//! +//! Demonstrates the toolchain on three increasingly complex stabilizer codes: +//! +//! - 3-qubit bit-flip code (2 stabilizers): protects against single X errors. +//! - 8-qubit Z-rep code (7 stabilizers): scales to larger generator counts. +//! - GHZ state with global parity (1 stabilizer of all Zs): tests +//! entanglement-aware fidelity. +//! +//! For each code: +//! - Prepare |`0_L`⟩ via Clifford circuit. +//! - Verify codespace fidelity = 1.0 using `StabMps::code_state_fidelity`. +//! - Inject per-qubit depolarizing noise via +//! `StabMps::apply_depolarizing_all`, observe the fidelity drop. +//! - Confirm `for_sparse_t()` preset and `auto_grow_bond_dim` work. +//! +//! Now also includes a correct Steane [[7, 1, 3]] CSS code encoder + +//! codespace fidelity verification. + +use pecos_core::QubitId; +use pecos_simulators::CliffordGateable; +use pecos_stab_tn::stab_mps::{PauliKind, StabMps}; +use std::time::Instant; + +/// 3-qubit bit-flip code: |`0_L`⟩ = |000⟩, |`1_L`⟩ = |111⟩. +/// Stabilizers: `Z_0Z_1`, `Z_1Z_2`. +fn bit_flip_3q_stabilizers() -> Vec> { + vec![ + vec![(0, PauliKind::Z), (1, PauliKind::Z)], + vec![(1, PauliKind::Z), (2, PauliKind::Z)], + ] +} + +/// N-qubit Z-repetition code: stabilizers `Z_iZ`_{i+1} for i = 0..n-2. +fn z_rep_stabilizers(n: usize) -> Vec> { + (0..n - 1) + .map(|i| vec![(i, PauliKind::Z), (i + 1, PauliKind::Z)]) + .collect() +} + +/// Steane [[7, 1, 3]] CSS code stabilizers. Based on Hamming [7,4,3] +/// parity-check matrix +/// H = [[0,0,0,1,1,1,1], +/// [0,1,1,0,0,1,1], +/// [1,0,1,0,1,0,1]] +/// X-stabilizers = {g1, g2, g3} from each row's X-support; Z-stabilizers +/// = {g4, g5, g6} from each row's Z-support (self-dual CSS). +fn steane_stabilizers() -> Vec> { + vec![ + // X-type + vec![ + (3, PauliKind::X), + (4, PauliKind::X), + (5, PauliKind::X), + (6, PauliKind::X), + ], + vec![ + (1, PauliKind::X), + (2, PauliKind::X), + (5, PauliKind::X), + (6, PauliKind::X), + ], + vec![ + (0, PauliKind::X), + (2, PauliKind::X), + (4, PauliKind::X), + (6, PauliKind::X), + ], + // Z-type + vec![ + (3, PauliKind::Z), + (4, PauliKind::Z), + (5, PauliKind::Z), + (6, PauliKind::Z), + ], + vec![ + (1, PauliKind::Z), + (2, PauliKind::Z), + (5, PauliKind::Z), + (6, PauliKind::Z), + ], + vec![ + (0, PauliKind::Z), + (2, PauliKind::Z), + (4, PauliKind::Z), + (6, PauliKind::Z), + ], + ] +} + +/// Prepare the logical |`0_L`⟩ of the Steane [[7, 1, 3]] CSS code using a +/// standard CX-cascade encoder (no ancillas). Pivots are chosen as +/// qubits {0, 1, 3} — each belongs to exactly one X-stabilizer, so +/// they can Hadamard independently and CX outward without cross- +/// contamination. +fn prepare_steane_logical_zero(stn: &mut StabMps) { + // H on pivots. + stn.h(&[QubitId(0), QubitId(1), QubitId(3)]); + // g1 = X_3X_4X_5X_6: CX from pivot 3 to 4, 5, 6. + stn.cx(&[(QubitId(3), QubitId(4))]); + stn.cx(&[(QubitId(3), QubitId(5))]); + stn.cx(&[(QubitId(3), QubitId(6))]); + // g2 = X_1X_2X_5X_6: CX from pivot 1 to 2, 5, 6. + stn.cx(&[(QubitId(1), QubitId(2))]); + stn.cx(&[(QubitId(1), QubitId(5))]); + stn.cx(&[(QubitId(1), QubitId(6))]); + // g3 = X_0X_2X_4X_6: CX from pivot 0 to 2, 4, 6. + stn.cx(&[(QubitId(0), QubitId(2))]); + stn.cx(&[(QubitId(0), QubitId(4))]); + stn.cx(&[(QubitId(0), QubitId(6))]); +} + +/// Extract the Steane syndrome via one ancilla per stabilizer generator +/// (6 ancillas total for 7 data + 6 ancilla = 13 qubit layout). For each +/// X-stabilizer, prep ancilla in |+⟩ via H, apply CX from ancilla to +/// each qubit in the stabilizer support, then measure ancilla in X +/// basis (H + Z-measurement). For each Z-stabilizer, prep ancilla in +/// |0⟩, apply CX from each data qubit in support to ancilla, measure +/// ancilla in Z basis. +/// +/// Returns the 6-bit syndrome (MSB first: g1..g6 in order of +/// `steane_stabilizers()`). +fn steane_syndrome_extraction(stn: &mut StabMps, ancilla_base: usize) -> [bool; 6] { + let mut syndrome = [false; 6]; + let stabs = steane_stabilizers(); + for (i, generator) in stabs.iter().enumerate() { + let anc = QubitId(ancilla_base + i); + let is_x_type = generator.iter().all(|&(_, k)| k == PauliKind::X); + if is_x_type { + // Prep |+⟩ ancilla, CX(anc, data) for each data in support, + // measure in X basis (H + mz). + stn.h(&[anc]); + for &(q, _) in generator { + stn.cx(&[(anc, QubitId(q))]); + } + stn.h(&[anc]); + syndrome[i] = stn.mz(&[anc])[0].outcome; + } else { + // Z-type: prep |0⟩, CX(data, anc) for each data, measure Z. + for &(q, _) in generator { + stn.cx(&[(QubitId(q), anc)]); + } + syndrome[i] = stn.mz(&[anc])[0].outcome; + } + } + syndrome +} + +/// Run a Steane prep + noise + syndrome extraction cycle across many shots. +/// Returns (`detection_count`, `any_errors_count)`: +/// - `detection_count`: shots where the syndrome is non-zero. +/// - `any_errors_count`: shots where depolarizing injected at least one non-I error. +fn steane_syndrome_detection_rate(p_noise: f64, num_shots: u64) -> (usize, usize) { + let mut detections = 0; + let mut any_errors = 0; + for shot in 0..num_shots { + // 7 data + 6 ancillas = 13 qubits. + let mut stn = StabMps::builder(13).seed(shot).for_sparse_t().build(); + prepare_steane_logical_zero(&mut stn); + // Inject per-data-qubit depolarizing. + let data_qubits: Vec = (0..7).map(QubitId).collect(); + let mut had_error = false; + for &q in &data_qubits { + if stn.apply_depolarizing(q, p_noise).is_some() { + had_error = true; + } + } + if had_error { + any_errors += 1; + } + let syndrome = steane_syndrome_extraction(&mut stn, 7); + let syndrome_nonzero = syndrome.iter().any(|&b| b); + if had_error && syndrome_nonzero { + detections += 1; + } + } + (detections, any_errors) +} + +/// GHZ state stabilizers: `X_0X_1...X`_{n-1}, `Z_iZ`_{i+1} for each pair. +fn ghz_stabilizers(n: usize) -> Vec> { + let mut stabs: Vec> = (0..n - 1) + .map(|i| vec![(i, PauliKind::Z), (i + 1, PauliKind::Z)]) + .collect(); + stabs.push((0..n).map(|i| (i, PauliKind::X)).collect()); + stabs +} + +fn run_code_scenario( + name: &str, + num_qubits: usize, + stabs: &[Vec<(usize, PauliKind)>], + prep: impl Fn(&mut StabMps), + p_noise: f64, + num_shots: usize, +) { + println!(); + println!( + "=== {name} ({num_qubits} qubits, {} stabilizer generators) ===", + stabs.len() + ); + + // Phase 1: noiseless prep + codespace fidelity check. + let start = Instant::now(); + let mut stn = StabMps::builder(num_qubits).seed(42).for_sparse_t().build(); + prep(&mut stn); + let prep_time = start.elapsed().as_secs_f64(); + let f_clean = stn.code_state_fidelity(stabs); + println!("Phase 1: noiseless prep"); + println!(" prep + fidelity time: {prep_time:.4} s"); + println!(" fidelity: {f_clean:.6} (expected 1.0)"); + if (f_clean - 1.0).abs() > 1e-9 { + println!(" WARNING: prep circuit does not produce |0_L⟩"); + return; + } + + // Phase 2: prep + depolarizing noise, average across shots. + let start = Instant::now(); + let mut total_fidelity = 0.0; + let qubits: Vec = (0..num_qubits).map(QubitId).collect(); + for shot in 0..num_shots { + let mut stn_noisy = StabMps::builder(num_qubits) + .seed(100 + shot as u64) + .for_sparse_t() + .build(); + prep(&mut stn_noisy); + stn_noisy.apply_depolarizing_all(&qubits, p_noise); + total_fidelity += stn_noisy.code_state_fidelity(stabs); + } + let avg_fidelity = total_fidelity / num_shots as f64; + let noisy_time = start.elapsed().as_secs_f64(); + println!("Phase 2: prep + per-qubit depolarizing (p = {p_noise:.3})"); + println!( + " total time: {noisy_time:.4} s ({:.2} ms/shot)", + noisy_time * 1000.0 / num_shots as f64 + ); + println!(" avg fidelity: {avg_fidelity:.6}"); + println!( + " drop: {:.4} (1.0 - avg_fidelity)", + 1.0 - avg_fidelity + ); +} + +fn main() { + println!("End-to-end QEC code demo using STN"); + println!("{:-<70}", ""); + println!( + "Toolchain: StabMps::builder().for_sparse_t() + apply_depolarizing_all + code_state_fidelity" + ); + + // 3-qubit bit-flip code: trivial prep (|000⟩ already in code). + run_code_scenario( + "3-qubit bit-flip code (Z-rep, k=2)", + 3, + &bit_flip_3q_stabilizers(), + |_stn| { /* |000⟩ default state */ }, + 0.05, + 500, + ); + + // 8-qubit Z-repetition code: |0^N⟩ prep is trivial. + run_code_scenario( + "8-qubit Z-repetition code (k=7)", + 8, + &z_rep_stabilizers(8), + |_stn| {}, + 0.02, + 200, + ); + + // GHZ state on 6 qubits: H + CX cascade. + run_code_scenario( + "6-qubit GHZ state (k=6: 5 ZZ + 1 XX...X)", + 6, + &ghz_stabilizers(6), + |stn| { + stn.h(&[QubitId(0)]); + for q in 0..5 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + }, + 0.01, + 200, + ); + + // Steane [[7, 1, 3]] code: standard CSS encoder. + run_code_scenario( + "Steane [[7, 1, 3]] CSS code (k=6: 3 X-type + 3 Z-type)", + 7, + &steane_stabilizers(), + prepare_steane_logical_zero, + 0.01, + 200, + ); + + // --- Steane syndrome extraction with ancillas --- + println!(); + println!("{:-<70}", ""); + println!("Steane syndrome extraction cycle (prep + noise + ancilla syndrome):"); + println!(" Detection ratio (syndrome non-zero / noise injected):"); + let num_cycles = 500; + for &p in &[0.001_f64, 0.005, 0.01, 0.02, 0.05] { + let (detections, any_errors) = steane_syndrome_detection_rate(p, num_cycles); + let detection_ratio = if any_errors == 0 { + 0.0 + } else { + detections as f64 / any_errors as f64 + }; + println!( + " p={p:.3}: {detections}/{any_errors} noisy cycles triggered syndrome ({:.1}%)", + detection_ratio * 100.0 + ); + } + + // --- Pauli frame tracking: noise-injection speedup at scale --- + println!(); + println!("{:-<70}", ""); + println!("Pauli frame tracking: noise-injection scaling (n=32, 10k injections):"); + let n_large = 32; + let num_injects = 10_000; + + let start = Instant::now(); + let mut stn_eager = StabMps::builder(n_large).seed(42).build(); + for _ in 0..num_injects { + stn_eager.apply_depolarizing(QubitId(0), 1.0); + } + let t_eager = start.elapsed().as_secs_f64(); + + let start = Instant::now(); + let mut stn_frame = StabMps::builder(n_large) + .seed(42) + .pauli_frame_tracking(true) + .build(); + for _ in 0..num_injects { + stn_frame.apply_depolarizing(QubitId(0), 1.0); + } + let t_frame = start.elapsed().as_secs_f64(); + + println!(" eager (apply to tableau): {t_eager:.4} s"); + println!(" frame tracking (O(1) per inj): {t_frame:.4} s"); + println!( + " speedup: {:.2}×", + t_eager / t_frame + ); + + println!(); + println!("{:-<70}", ""); + println!("Demo complete. The StabMps::for_sparse_t() preset plus apply_depolarizing_all"); + println!("+ code_state_fidelity gives a complete API for QEC code-state"); + println!("verification + noise impact studies. Adding pauli_frame_tracking"); + println!("eliminates per-injection tableau overhead — useful for noise-heavy"); + println!("shot sweeps."); +} diff --git a/exp/pecos-stab-tn/examples/tier3_profile.rs b/exp/pecos-stab-tn/examples/tier3_profile.rs new file mode 100644 index 000000000..cc92873ca --- /dev/null +++ b/exp/pecos-stab-tn/examples/tier3_profile.rs @@ -0,0 +1,152 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Tier 3 profiling: measure absolute cost of the operations we'd +//! optimize with `cliff_frame` deferral, sub-MPO long-range, and CD +//! Loschmidt Method 2. Decides whether each Tier 3 item is worth the +//! implementation effort. +//! +//! Usage: `cargo run --release --example tier3_profile`. + +use pecos_core::QubitId; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable}; +use pecos_stab_tn::stab_mps::StabMps; +use std::time::Instant; + +fn bench(label: &str, ops: usize, f: impl FnOnce()) { + let start = Instant::now(); + f(); + let elapsed = start.elapsed().as_secs_f64(); + let per_op_us = elapsed * 1e6 / ops as f64; + println!(" {label:<48} {elapsed:>8.4} s ({per_op_us:>6.2} µs/op × {ops})"); +} + +fn main() { + use pecos_simulators::CHForm; + println!("Tier 3 profiling -- measure where cliff_frame / sub-MPO / CD2 would help"); + println!("{:-<80}", ""); + + // ---- 1. Single-qubit Clifford cost (cliff_frame target) ---- + println!(); + println!("1. Single-qubit Clifford batching candidate (cliff_frame target):"); + println!(" Question: how much of QEC time is spent on single-qubit Cliffords?"); + + let n = 32; + let num_ops = 100_000; + let mut stn = StabMps::builder(n).seed(42).build(); + bench("H × 100k on random qubits", num_ops, || { + let mut rng = 12345u64; + for _ in 0..num_ops { + rng ^= rng << 13; + rng ^= rng >> 7; + rng ^= rng << 17; + let q = (rng as usize) % n; + stn.h(&[QubitId(q)]); + } + }); + + let mut stn = StabMps::builder(n).seed(42).build(); + bench("SZ × 100k on random qubits", num_ops, || { + let mut rng = 54321u64; + for _ in 0..num_ops { + rng ^= rng << 13; + rng ^= rng >> 7; + rng ^= rng << 17; + let q = (rng as usize) % n; + stn.sz(&[QubitId(q)]); + } + }); + + // ---- 2. Long-range CX/CZ cost (sub-MPO target) ---- + // For Clifford gates, tableau handles long-range in O(n) regardless. + // Sub-MPO would help only for NON-CLIFFORD ops applied to an entangled + // MPS where the pre_reduce path needs long-range compensation — but + // we've already switched to the pragmatic-fix path that avoids this. + println!(); + println!("2. Long-range 2-qubit Clifford cost (sub-MPO target):"); + println!(" Question: does long-range CX hurt STN, given the tableau-only path?"); + + let n = 32; + let num_ops = 100_000; + let mut stn = StabMps::builder(n).seed(42).build(); + bench("CX(0, n/2) × 100k (max-distance)", num_ops, || { + for _ in 0..num_ops { + stn.cx(&[(QubitId(0), QubitId(n / 2))]); + } + }); + + let mut stn = StabMps::builder(n).seed(42).build(); + bench("CX(0, 1) × 100k (adjacent)", num_ops, || { + for _ in 0..num_ops { + stn.cx(&[(QubitId(0), QubitId(1))]); + } + }); + + // Long-range CX inside a non-Clifford path (where it could matter). + println!(); + println!(" Non-Clifford workload where MPS bond activity dominates:"); + + let n = 12; + let num_rounds = 50; + let mut stn = StabMps::builder(n).seed(42).for_sparse_t().build(); + let t = pecos_core::Angle64::QUARTER_TURN / 2u64; + bench("T+longrange-CX round × 50 (n=12)", num_rounds, || { + for _ in 0..num_rounds { + for q in 0..n { + stn.rz(t, &[QubitId(q)]); + } + for q in 0..n / 2 { + stn.cx(&[(QubitId(q), QubitId(n - 1 - q))]); + } + } + }); + println!(" final bond dim: {}", stn.max_bond_dim()); + + // ---- 3. MC overlap_with_stabilizer cost (CD Loschmidt target) ---- + println!(); + println!("3. MC overlap_with_stabilizer (CD Loschmidt Method 1 we have):"); + println!(" Question: is the MC variance a bottleneck for code-state fidelity?"); + + let n = 20; + let mut s = CHForm::new_with_seed(n, 42); + s.h(&[QubitId(0)]); + for q in 0..n - 1 { + s.cx(&[(QubitId(q), QubitId(q + 1))]); + } + let mut stn = StabMps::with_seed(n, 7); + stn.h(&[QubitId(0)]); + for q in 0..n - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + + let num_samples_small = 100; + let num_samples_medium = 1000; + let num_samples_large = 10_000; + + bench("overlap n=20 GHZ (100 samples)", 1, || { + let _ = stn.overlap_with_stabilizer(&s, num_samples_small, None); + }); + bench("overlap n=20 GHZ (1k samples)", 1, || { + let _ = stn.overlap_with_stabilizer(&s, num_samples_medium, None); + }); + bench("overlap n=20 GHZ (10k samples)", 1, || { + let _ = stn.overlap_with_stabilizer(&s, num_samples_large, None); + }); + + println!(); + println!("{:-<80}", ""); + println!("Interpretation:"); + println!(" 1. If single-qubit Clifford time << total circuit time → cliff_frame skip."); + println!(" 2. If long-range CX time ≈ adjacent CX time → sub-MPO skip."); + println!(" 3. If overlap scales linearly with samples → CD Method 2 (deterministic)"); + println!(" is worthwhile only if we need << sampling error at fixed compute."); +} diff --git a/exp/pecos-stab-tn/src/errors.rs b/exp/pecos-stab-tn/src/errors.rs new file mode 100644 index 000000000..56ed05d6c --- /dev/null +++ b/exp/pecos-stab-tn/src/errors.rs @@ -0,0 +1,32 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +use thiserror::Error; + +#[derive(Error, Debug)] +pub enum MpsError { + #[error("site index {index} out of bounds (num_sites = {num_sites})")] + SiteOutOfBounds { index: usize, num_sites: usize }, + + #[error("gate dimension mismatch: expected {expected}x{expected}, got {rows}x{cols}")] + GateDimMismatch { + expected: usize, + rows: usize, + cols: usize, + }, + + #[error("SVD failed to converge")] + SvdFailed, + + #[error("sites {q0} and {q1} are not adjacent")] + NonAdjacentSites { q0: usize, q1: usize }, +} diff --git a/exp/pecos-stab-tn/src/lib.rs b/exp/pecos-stab-tn/src/lib.rs new file mode 100644 index 000000000..9e1b92d40 --- /dev/null +++ b/exp/pecos-stab-tn/src/lib.rs @@ -0,0 +1,32 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Hybrid stabilizer + tensor network simulation methods. +//! +//! This crate provides experimental implementations of methods that combine +//! Clifford/stabilizer tracking with tensor network (MPS) representations: +//! +//! - **MPS**: Matrix Product State engine (SVD truncation, gate application, contraction) +//! - **STN**: Stabilizer Tensor Networks (tableau + MPS coefficients) +//! - **MAST**: Magic state injection Augmented STN (deferred non-Clifford cost) +//! +//! # References +//! +//! - Masot-Llima, Garcia-Saez. "Stabilizer Tensor Networks: Universal Quantum Simulator +//! on a Basis of Stabilizer States." PRL 133, 230601 (2024). arXiv:2403.08724. +//! - Nakhl, Harper, West, Dowling, Sevior, Quella, Usman. "Stabilizer Tensor Networks +//! with Magic State Injection." PRL 134, 190602 (2025). arXiv:2411.12482. +//! - Reference implementation: + +pub mod errors; +pub mod mps; +pub mod stab_mps; diff --git a/exp/pecos-stab-tn/src/mps.rs b/exp/pecos-stab-tn/src/mps.rs new file mode 100644 index 000000000..9d5502df6 --- /dev/null +++ b/exp/pecos-stab-tn/src/mps.rs @@ -0,0 +1,1677 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Matrix Product State (MPS) engine. +//! +//! An MPS represents a quantum state as a chain of tensors: +//! +//! ```text +//! |psi> = sum_{s_0, ..., s_{N-1}} A[0]^{s_0} A[1]^{s_1} ... A[N-1]^{s_{N-1}} |s_0 s_1 ... s_{N-1}> +//! ``` +//! +//! Each site tensor `A[i]^{s_i}` is a matrix of shape `(chi_left, chi_right)`. +//! For all physical indices `s_i` together, site `i` is stored as a single +//! `DMatrix` of shape `(chi_left, d * chi_right)`, where columns +//! `[s * chi_right .. (s+1) * chi_right]` correspond to physical index `s`. + +pub mod canon; +pub mod svd; +pub mod tensor; + +use crate::errors::MpsError; +use nalgebra::DMatrix; +use num_complex::Complex64; +use rayon::prelude::*; +use tensor::{ + contract_two_sites, phys_block, reshape_left_ungroup, reshape_two_site_for_svd, set_phys_block, +}; + +/// Configuration for MPS truncation. +#[derive(Clone, Debug)] +pub struct MpsConfig { + /// Maximum bond dimension (hard cap). Singular values beyond this are discarded. + pub max_bond_dim: usize, + /// Minimum singular value to keep (absolute cutoff). + pub svd_cutoff: f64, + /// Maximum relative truncation error per SVD. + /// When set, singular values are kept until the discarded weight + /// (sum of discarded `s_i^2` / sum of all `s_i^2`) exceeds this threshold. + /// This allows low-entanglement bonds to use small chi (fast) while + /// high-entanglement bonds grow up to `max_bond_dim` (accurate). + /// None = disabled (fixed `max_bond_dim` only). + pub max_truncation_error: Option, + /// Use rayon for parallelizing independent MPS operations. + pub parallel: bool, +} + +impl Default for MpsConfig { + fn default() -> Self { + Self { + max_bond_dim: 64, + svd_cutoff: 1e-12, + max_truncation_error: None, + parallel: false, + } + } +} + +/// Matrix Product State with open boundary conditions. +/// +/// Physical dimension is `d` (2 for qubits). Site tensor `i` has shape +/// `(bond_dims[i], d * bond_dims[i+1])`. +pub struct Mps { + num_sites: usize, + phys_dim: usize, + tensors: Vec>, + /// Bond dimensions: length `num_sites + 1`. + /// `bond_dims[0] = 1` (left boundary), `bond_dims[num_sites] = 1` (right boundary). + bond_dims: Vec, + config: MpsConfig, + /// Accumulated truncation error: `1 - ∏(1 - step_discarded_weight)`. + /// Approximates total 1-fidelity loss from SVD truncations over the lifetime + /// of this MPS. Each truncated SVD updates this via + /// `err = err + (1 - err) * step_discarded_weight`. + truncation_error: f64, + /// Number of SVDs that were capped by `max_bond_dim` (rank-limited rather + /// than cutoff-limited). If > 0 the caller may want to raise `max_bond_dim`. + bond_cap_hits: u64, +} + +impl Mps { + /// Create an MPS initialized to |00...0> with bond dimension 1 everywhere. + #[must_use] + pub fn new(num_sites: usize, config: MpsConfig) -> Self { + let d = 2; + let bond_dims = vec![1; num_sites + 1]; + let mut tensors = Vec::with_capacity(num_sites); + for _ in 0..num_sites { + // Each tensor is (1, d*1) = (1, 2), representing [1, 0] (amplitude 1 for |0>) + let mut t = DMatrix::zeros(1, d); + t[(0, 0)] = Complex64::new(1.0, 0.0); + tensors.push(t); + } + Self { + num_sites, + phys_dim: d, + tensors, + bond_dims, + config, + truncation_error: 0.0, + bond_cap_hits: 0, + } + } + + /// Accumulated truncation error: `1 - ∏(1 - step_discarded_weight)`. + /// Zero for exact simulations; bounded above by the sum of per-step + /// discarded weights. Approximates `1 - |⟨ψ_true|ψ_truncated⟩|²`. + #[must_use] + pub fn truncation_error(&self) -> f64 { + self.truncation_error + } + + /// Count of SVDs where the `max_bond_dim` cap was binding. If > 0 the + /// state is under-resolved and the user may want to increase the cap. + #[must_use] + pub fn bond_cap_hits(&self) -> u64 { + self.bond_cap_hits + } + + /// Reset truncation diagnostics (keep state). + pub fn reset_truncation_stats(&mut self) { + self.truncation_error = 0.0; + self.bond_cap_hits = 0; + } + + /// Record the outcome of one truncated SVD for telemetry. + pub(crate) fn record_truncation(&mut self, discarded_weight: f64, hit_cap: bool) { + if discarded_weight > 0.0 { + self.truncation_error += (1.0 - self.truncation_error) * discarded_weight; + } + if hit_cap { + self.bond_cap_hits += 1; + } + } + + #[must_use] + pub fn num_sites(&self) -> usize { + self.num_sites + } + + #[must_use] + pub fn phys_dim(&self) -> usize { + self.phys_dim + } + + /// Bond dimension at bond `i` (between sites `i-1` and `i`). + #[must_use] + pub fn bond_dim(&self, bond: usize) -> usize { + self.bond_dims[bond] + } + + #[must_use] + pub fn max_bond_dim(&self) -> usize { + *self.bond_dims.iter().max().unwrap_or(&1) + } + + #[must_use] + pub fn config(&self) -> &MpsConfig { + &self.config + } + + /// Update the max bond dimension cap. Used by adaptive bond-dim + /// auto-grow logic (e.g., `StabMps::auto_grow_bond_dim_if_needed`). + /// Does not retroactively change existing tensors; takes effect on + /// subsequent SVD truncations. + pub fn set_max_bond_dim(&mut self, new_cap: usize) { + self.config.max_bond_dim = new_cap; + } + + /// Multiply the entire MPS by a scalar (absorbed into the first tensor). + pub fn scale(&mut self, scalar: Complex64) { + if self.tensors.is_empty() { + return; + } + self.tensors[0] *= scalar; + } + + /// Apply a single-site gate (d x d unitary matrix) to site `q`. + /// + /// For each pair of physical indices (`sigma_out`, `sigma_in)`: + /// A'[`alpha_l`, `sigma_out`, `alpha_r`] = sum_{`sigma_in`} gate[`sigma_out`, `sigma_in`] * A[`alpha_l`, `sigma_in`, `alpha_r`] + /// + /// # Errors + /// + /// Returns [`MpsError::GateDimMismatch`] if the gate dimensions don't match the + /// physical dimension, or [`MpsError::SiteOutOfBounds`] if `q` is out of range. + /// Apply a 2×2 gate to a qubit site using raw coefficients (no DMatrix allocation). + /// Gate is specified as [[g00, g01], [g10, g11]]. + #[inline] + pub fn apply_gate_2x2( + &mut self, + q: usize, + g: [[Complex64; 2]; 2], + ) { + debug_assert!(q < self.num_sites); + let chi_l = self.bond_dims[q]; + let chi_r = self.bond_dims[q + 1]; + if chi_l == 1 && chi_r == 1 { + let a0 = self.tensors[q][(0, 0)]; + let a1 = self.tensors[q][(0, 1)]; + self.tensors[q][(0, 0)] = g[0][0] * a0 + g[0][1] * a1; + self.tensors[q][(0, 1)] = g[1][0] * a0 + g[1][1] * a1; + } else { + // General path: iterate over bond dimensions + for alpha_l in 0..chi_l { + for alpha_r in 0..chi_r { + let a0 = self.tensors[q][(alpha_l, 0 * chi_r + alpha_r)]; + let a1 = self.tensors[q][(alpha_l, 1 * chi_r + alpha_r)]; + self.tensors[q][(alpha_l, 0 * chi_r + alpha_r)] = g[0][0] * a0 + g[0][1] * a1; + self.tensors[q][(alpha_l, 1 * chi_r + alpha_r)] = g[1][0] * a0 + g[1][1] * a1; + } + } + } + } + + pub fn apply_one_site_gate( + &mut self, + q: usize, + gate: &DMatrix, + ) -> Result<(), MpsError> { + let d = self.phys_dim; + if gate.nrows() != d || gate.ncols() != d { + return Err(MpsError::GateDimMismatch { + expected: d, + rows: gate.nrows(), + cols: gate.ncols(), + }); + } + if q >= self.num_sites { + return Err(MpsError::SiteOutOfBounds { + index: q, + num_sites: self.num_sites, + }); + } + + let chi_l = self.bond_dims[q]; + let chi_r = self.bond_dims[q + 1]; + + // Fast path for d=2, bd=1: just a 2×2 matrix times a 2-vector, no allocation. + if d == 2 && chi_l == 1 && chi_r == 1 { + let a0 = self.tensors[q][(0, 0)]; + let a1 = self.tensors[q][(0, 1)]; + self.tensors[q][(0, 0)] = gate[(0, 0)] * a0 + gate[(0, 1)] * a1; + self.tensors[q][(0, 1)] = gate[(1, 0)] * a0 + gate[(1, 1)] * a1; + return Ok(()); + } + + // Collect old blocks + let old_blocks: Vec> = (0..d) + .map(|s| phys_block(&self.tensors[q], s, chi_r)) + .collect(); + + // Compute new blocks: new_block[sigma_out] = sum_sigma_in gate[sigma_out, sigma_in] * old_block[sigma_in] + for sigma_out in 0..d { + let mut new_block = DMatrix::zeros(chi_l, chi_r); + for (sigma_in, old_block) in old_blocks.iter().enumerate() { + let coeff = gate[(sigma_out, sigma_in)]; + if coeff != Complex64::new(0.0, 0.0) { + new_block += old_block * coeff; + } + } + set_phys_block(&mut self.tensors[q], sigma_out, chi_r, &new_block); + } + Ok(()) + } + + /// Apply a diagonal single-site gate: diag(c0, c1, ...) to site `q`. + /// + /// Just scales each physical block by the corresponding coefficient. + /// + /// # Errors + /// + /// Returns [`MpsError::GateDimMismatch`] if `coeffs.len()` differs from the + /// physical dimension, or [`MpsError::SiteOutOfBounds`] if `q` is out of range. + pub fn apply_diagonal_one_site( + &mut self, + q: usize, + coeffs: &[Complex64], + ) -> Result<(), MpsError> { + let d = self.phys_dim; + if coeffs.len() != d { + return Err(MpsError::GateDimMismatch { + expected: d, + rows: d, + cols: d, + }); + } + if q >= self.num_sites { + return Err(MpsError::SiteOutOfBounds { + index: q, + num_sites: self.num_sites, + }); + } + + let chi_r = self.bond_dims[q + 1]; + for (sigma, &c) in coeffs.iter().enumerate() { + let start_col = sigma * chi_r; + for j in 0..chi_r { + for i in 0..self.bond_dims[q] { + self.tensors[q][(i, start_col + j)] *= c; + } + } + } + Ok(()) + } + + /// Apply a two-site gate (d^2 x d^2 matrix) to adjacent sites (q, q+1). + /// + /// The gate acts on the combined physical space of both sites. + /// Row/column index = `sigma_l * d + sigma_r`. + /// + /// After applying the gate, the two-site tensor is split via SVD with truncation. + /// + /// # Errors + /// + /// Returns [`MpsError::GateDimMismatch`] if the gate isn't d^2 x d^2, + /// [`MpsError::SiteOutOfBounds`] if q+1 exceeds the chain, or + /// [`MpsError::SvdFailed`] if the SVD decomposition fails. + pub fn apply_two_site_gate( + &mut self, + q: usize, + gate: &DMatrix, + ) -> Result<(), MpsError> { + let d = self.phys_dim; + let d2 = d * d; + if gate.nrows() != d2 || gate.ncols() != d2 { + return Err(MpsError::GateDimMismatch { + expected: d2, + rows: gate.nrows(), + cols: gate.ncols(), + }); + } + if q + 1 >= self.num_sites { + return Err(MpsError::NonAdjacentSites { q0: q, q1: q + 1 }); + } + + let chi_l = self.bond_dims[q]; + let chi_mid = self.bond_dims[q + 1]; + let chi_r = self.bond_dims[q + 2]; + + // Fast path: when all three bond dims are 1, the two-site state + // is a product of two d-vectors. We can apply the d²×d² gate + // and do a rank-1 check / 2×2 SVD inline without DMatrix allocation. + if d == 2 && chi_l == 1 && chi_mid == 1 && chi_r == 1 { + return self.apply_two_site_gate_bd1(q, gate); + } + + // Contract the two site tensors into a two-site tensor + let two_site = contract_two_sites( + &self.tensors[q], + chi_l, + chi_mid, + &self.tensors[q + 1], + chi_r, + d, + ); + + // Apply the gate to the physical indices + // two_site: (chi_l, d * d * chi_r) + // We need to contract gate[sigma_l_out * d + sigma_r_out, sigma_l_in * d + sigma_r_in] + // with two_site[alpha_l, sigma_l_in * d * chi_r + sigma_r_in * chi_r + alpha_r] + let mut gated = DMatrix::zeros(chi_l, d * d * chi_r); + for alpha_l in 0..chi_l { + for alpha_r in 0..chi_r { + for sigma_l_out in 0..d { + for sigma_r_out in 0..d { + let mut val = Complex64::new(0.0, 0.0); + for sigma_l_in in 0..d { + for sigma_r_in in 0..d { + let gate_val = gate + [(sigma_l_out * d + sigma_r_out, sigma_l_in * d + sigma_r_in)]; + if gate_val != Complex64::new(0.0, 0.0) { + let in_col = (sigma_l_in * d + sigma_r_in) * chi_r + alpha_r; + val += gate_val * two_site[(alpha_l, in_col)]; + } + } + } + let out_col = (sigma_l_out * d + sigma_r_out) * chi_r + alpha_r; + gated[(alpha_l, out_col)] = val; + } + } + } + } + + // Reshape for SVD: (chi_l * d, d * chi_r) + let svd_matrix = reshape_two_site_for_svd(&gated, chi_l, chi_r, d); + + // SVD split with truncation + let (u_s, vt, disc, hit) = svd::truncated_svd_left_absorb_with_error( + &svd_matrix, + self.config.max_bond_dim, + self.config.svd_cutoff, + self.config.max_truncation_error, + )?; + self.record_truncation(disc, hit); + + let new_chi = u_s.ncols(); + + // U_S: (chi_l * d, new_chi) -> reshape to (chi_l, d * new_chi) + self.tensors[q] = reshape_left_ungroup(&u_s, chi_l, d, new_chi); + + // Vt: (new_chi, d * chi_r) -- already in site tensor format + self.tensors[q + 1] = vt; + + // Update bond dimension + self.bond_dims[q + 1] = new_chi; + + Ok(()) + } + + /// Fast path for `apply_two_site_gate` when d=2 and all bond dims are 1. + /// + /// The two-site state is just 4 complex numbers. We apply the 4×4 gate, + /// then do a 2×2 SVD inline to split back into two site tensors. + /// Avoids all DMatrix heap allocation. + fn apply_two_site_gate_bd1( + &mut self, + q: usize, + gate: &DMatrix, + ) -> Result<(), MpsError> { + let zero = Complex64::new(0.0, 0.0); + + // Read the two 1×2 site tensors as scalars + let a0 = self.tensors[q][(0, 0)]; + let a1 = self.tensors[q][(0, 1)]; + let b0 = self.tensors[q + 1][(0, 0)]; + let b1 = self.tensors[q + 1][(0, 1)]; + + // Combined 4-vector: |00⟩, |01⟩, |10⟩, |11⟩ + let psi_in = [a0 * b0, a0 * b1, a1 * b0, a1 * b1]; + + // Apply gate + let mut psi_out = [zero; 4]; + for i in 0..4 { + let mut v = zero; + for j in 0..4 { + let g = gate[(i, j)]; + if g != zero { + v += g * psi_in[j]; + } + } + psi_out[i] = v; + } + + // Reshape as 2×2 matrix M[sigma_l, sigma_r] for SVD: + // M = [[psi_out[0], psi_out[1]], [psi_out[2], psi_out[3]]] + let m00 = psi_out[0]; + let m01 = psi_out[1]; + let m10 = psi_out[2]; + let m11 = psi_out[3]; + + // Check if rank 1: det(M) ≈ 0 means we can stay at bd=1 + let det = m00 * m11 - m01 * m10; + if det.norm_sqr() < self.config.svd_cutoff * self.config.svd_cutoff { + // Rank 1: M ≈ u * v^T. Find the dominant column/row. + let col0_norm = m00.norm_sqr() + m10.norm_sqr(); + let col1_norm = m01.norm_sqr() + m11.norm_sqr(); + + if col0_norm > col1_norm { + // Use column 0 as left vector, compute right from it + let norm = col0_norm.sqrt(); + if norm < 1e-15 { + // Zero state — both tensors zero + self.tensors[q][(0, 0)] = zero; + self.tensors[q][(0, 1)] = zero; + self.tensors[q + 1][(0, 0)] = zero; + self.tensors[q + 1][(0, 1)] = zero; + } else { + let inv = Complex64::new(1.0 / norm, 0.0); + // Left tensor: normalized column 0 + self.tensors[q][(0, 0)] = m00 * inv; + self.tensors[q][(0, 1)] = m10 * inv; + // Right tensor: project row from left + let u0 = m00 * inv; + let u1 = m10 * inv; + self.tensors[q + 1][(0, 0)] = u0.conj() * m00 + u1.conj() * m10; + self.tensors[q + 1][(0, 1)] = u0.conj() * m01 + u1.conj() * m11; + } + } else { + let norm = col1_norm.sqrt(); + if norm < 1e-15 { + self.tensors[q][(0, 0)] = zero; + self.tensors[q][(0, 1)] = zero; + self.tensors[q + 1][(0, 0)] = zero; + self.tensors[q + 1][(0, 1)] = zero; + } else { + let inv = Complex64::new(1.0 / norm, 0.0); + self.tensors[q][(0, 0)] = m01 * inv; + self.tensors[q][(0, 1)] = m11 * inv; + let u0 = m01 * inv; + let u1 = m11 * inv; + self.tensors[q + 1][(0, 0)] = u0.conj() * m00 + u1.conj() * m10; + self.tensors[q + 1][(0, 1)] = u0.conj() * m01 + u1.conj() * m11; + } + } + // Bond dim stays 1 + } else { + // Rank 2: inline 2×2 SVD without nalgebra allocation. + // M = U * diag(σ₁,σ₂) * V†. Compute via M†M eigendecomposition. + // + // M†M = [[|m00|²+|m10|², m00'*m01+m10'*m11], + // [m01'*m00+m11'*m10, |m01|²+|m11|²]] + let a = m00.norm_sqr() + m10.norm_sqr(); // real + let d_val = m01.norm_sqr() + m11.norm_sqr(); // real + let b = m00.conj() * m01 + m10.conj() * m11; // complex + + // Eigenvalues of 2×2 Hermitian [[a,b],[b*,d]]: + // λ± = (a+d)/2 ± sqrt((a-d)²/4 + |b|²) + let sum = a + d_val; + let diff = a - d_val; + let disc_sq = diff * diff / 4.0 + b.norm_sqr(); + let disc_val = disc_sq.sqrt(); + let lambda1 = (sum / 2.0 + disc_val).max(0.0); + let lambda2 = (sum / 2.0 - disc_val).max(0.0); + let sigma1 = lambda1.sqrt(); + let sigma2 = lambda2.sqrt(); + + // Check if second singular value is below cutoff + let keep_both = sigma2 > self.config.svd_cutoff + && self.config.max_bond_dim >= 2; + + if !keep_both { + // Truncate to rank 1 (same as the rank-1 path above but + // the dominant singular vector is the eigenvector of M†M). + if sigma1 < 1e-15 { + self.tensors[q][(0, 0)] = zero; + self.tensors[q][(0, 1)] = zero; + self.tensors[q + 1][(0, 0)] = zero; + self.tensors[q + 1][(0, 1)] = zero; + } else { + // Right singular vector v1: eigenvector of M†M for λ₁ + // (M†M - λ₁I)v = 0. Use: v ∝ [b, λ₁-a] or [λ₁-d, b*] + let (v0, v1) = if (lambda1 - a).abs() > b.norm() * 0.5 { + let raw = (b, Complex64::new(lambda1 - a, 0.0)); + let n = (raw.0.norm_sqr() + raw.1.norm_sqr()).sqrt(); + (raw.0 / n, raw.1 / n) + } else { + let raw = (Complex64::new(lambda1 - d_val, 0.0), b.conj()); + let n = (raw.0.norm_sqr() + raw.1.norm_sqr()).sqrt(); + (raw.0 / n, raw.1 / n) + }; + // Left singular vector: u1 = M*v1 / σ₁ + let inv_s = Complex64::new(1.0 / sigma1, 0.0); + let u0 = (m00 * v0 + m01 * v1) * inv_s; + let u1 = (m10 * v0 + m11 * v1) * inv_s; + // Left tensor = u * σ₁ (absorbed) + self.tensors[q][(0, 0)] = u0 * Complex64::new(sigma1, 0.0); + self.tensors[q][(0, 1)] = u1 * Complex64::new(sigma1, 0.0); + // Right tensor = v† + self.tensors[q + 1][(0, 0)] = v0.conj(); + self.tensors[q + 1][(0, 1)] = v1.conj(); + } + // Record truncation if we dropped sigma2 + if sigma2 > self.config.svd_cutoff { + self.truncation_error = self.truncation_error.max(sigma2); + self.bond_cap_hits += 1; + } + } else { + // Keep both singular values: grow bond dim to 2. + // Right singular vectors from M†M eigenvectors. + let (v1_0, v1_1, v2_0, v2_1) = if b.norm() > 1e-15 { + let v1_raw = (b, Complex64::new(lambda1 - a, 0.0)); + let n1 = (v1_raw.0.norm_sqr() + v1_raw.1.norm_sqr()).sqrt(); + let v2_raw = (b, Complex64::new(lambda2 - a, 0.0)); + let n2 = (v2_raw.0.norm_sqr() + v2_raw.1.norm_sqr()).sqrt(); + (v1_raw.0 / n1, v1_raw.1 / n1, v2_raw.0 / n2, v2_raw.1 / n2) + } else { + // M†M is diagonal — eigenvectors are standard basis + if a >= d_val { + (Complex64::new(1.0, 0.0), zero, zero, Complex64::new(1.0, 0.0)) + } else { + (zero, Complex64::new(1.0, 0.0), Complex64::new(1.0, 0.0), zero) + } + }; + + // Left singular vectors: u_i = M * v_i / σ_i + let inv_s1 = if sigma1 > 1e-15 { Complex64::new(1.0 / sigma1, 0.0) } else { zero }; + let inv_s2 = if sigma2 > 1e-15 { Complex64::new(1.0 / sigma2, 0.0) } else { zero }; + + let u1_0 = (m00 * v1_0 + m01 * v1_1) * inv_s1; + let u1_1 = (m10 * v1_0 + m11 * v1_1) * inv_s1; + let u2_0 = (m00 * v2_0 + m01 * v2_1) * inv_s2; + let u2_1 = (m10 * v2_0 + m11 * v2_1) * inv_s2; + + // Left tensor: U*S absorbed, shape (1, 2*2) = (1, 4) + // Layout: [σ=0: (us_00, us_01), σ=1: (us_10, us_11)] + let s1 = Complex64::new(sigma1, 0.0); + let s2 = Complex64::new(sigma2, 0.0); + let mut t_left = DMatrix::zeros(1, 4); + t_left[(0, 0)] = u1_0 * s1; // σ=0, χ=0 + t_left[(0, 1)] = u2_0 * s2; // σ=0, χ=1 + t_left[(0, 2)] = u1_1 * s1; // σ=1, χ=0 + t_left[(0, 3)] = u2_1 * s2; // σ=1, χ=1 + self.tensors[q] = t_left; + + // Right tensor: V†, shape (2, 2) + let mut t_right = DMatrix::zeros(2, 2); + t_right[(0, 0)] = v1_0.conj(); // χ=0, σ=0 + t_right[(0, 1)] = v1_1.conj(); // χ=0, σ=1 + t_right[(1, 0)] = v2_0.conj(); // χ=1, σ=0 + t_right[(1, 1)] = v2_1.conj(); // χ=1, σ=1 + self.tensors[q + 1] = t_right; + + self.bond_dims[q + 1] = 2; + } + } + + Ok(()) + } + + /// Apply a two-site gate between arbitrary (possibly non-adjacent) sites. + /// + /// Uses SWAP gates to bring site `q1` adjacent to `q0`, applies the gate, + /// then SWAPs back. `q0 < q1` required. + /// + /// SWAP gates are unitary permutations that preserve the Schmidt spectrum, + /// so SVD truncation after each SWAP introduces minimal numerical drift. + /// The dominant error comes only from the actual gate application. + /// + /// # Errors + /// + /// Returns [`MpsError::NonAdjacentSites`] if `q0 >= q1`, + /// [`MpsError::SiteOutOfBounds`] if `q1` exceeds the chain, or + /// [`MpsError::SvdFailed`] if any intermediate SVD fails. + pub fn apply_long_range_two_site_gate( + &mut self, + q0: usize, + q1: usize, + gate: &DMatrix, + ) -> Result<(), MpsError> { + if q0 >= q1 { + return Err(MpsError::NonAdjacentSites { q0, q1 }); + } + if q1 >= self.num_sites { + return Err(MpsError::SiteOutOfBounds { + index: q1, + num_sites: self.num_sites, + }); + } + + // Adjacent case: apply directly + if q1 == q0 + 1 { + return self.apply_two_site_gate(q0, gate); + } + + // Fast path for bd=1: SWAP is just tensor swap (no gate application needed). + // Check if ALL bonds in the range [q0..q1+1] are bd=1. + let all_bd1 = self.phys_dim == 2 + && self.bond_dims[q0..=q1 + 1].iter().all(|&bd| bd <= 1); + + if all_bd1 { + // SWAP q1 leftward by swapping tensors (no SVD needed at bd=1) + for i in (q0 + 1..q1).rev() { + self.tensors.swap(i, i + 1); + } + // Apply the gate on the now-adjacent pair + self.apply_two_site_gate(q0, gate)?; + + if self.bond_dims[q0 + 1] == 1 { + // Result is still bd=1, can swap tensors back cheaply + for i in q0 + 1..q1 { + self.tensors.swap(i, i + 1); + } + } else { + // Gate grew bond dim — need proper SWAP gates to restore + // qubit order while maintaining correct tensor shapes. + let swap = DMatrix::from_row_slice( + 4, 4, + &[ + Complex64::new(1.0, 0.0), Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), Complex64::new(1.0, 0.0), + ], + ); + for i in q0 + 1..q1 { + self.apply_two_site_gate(i, &swap)?; + } + } + return Ok(()); + } + + // General path: SWAP chain via two-site gates. + let swap = DMatrix::from_row_slice( + 4, + 4, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + ], + ); + + // SWAP q1 leftward until it's adjacent to q0 + for i in (q0 + 1..q1).rev() { + self.apply_two_site_gate(i, &swap)?; + } + + // Apply the gate on the now-adjacent pair + self.apply_two_site_gate(q0, gate)?; + + // SWAP back + for i in q0 + 1..q1 { + self.apply_two_site_gate(i, &swap)?; + } + + Ok(()) + } + + /// Compute the squared norm `` by contracting the MPS with itself. + #[must_use] + pub fn norm_squared(&self) -> f64 { + // Contract from left to right, building the transfer matrix product. + // E[alpha, beta] = sum_{sigma} A*[alpha, sigma] A[beta, sigma] + // Start with E = 1x1 identity. + let d = self.phys_dim; + let mut transfer = DMatrix::from_element(1, 1, Complex64::new(1.0, 0.0)); + + for q in 0..self.num_sites { + let chi_r = self.bond_dims[q + 1]; + let t = &self.tensors[q]; + + // new_transfer[alpha_r, beta_r] = sum_{alpha_l, beta_l, sigma} + // transfer[alpha_l, beta_l] * conj(A[alpha_l, sigma, alpha_r]) * A[beta_l, sigma, beta_r] + let mut new_transfer = DMatrix::zeros(chi_r, chi_r); + for sigma in 0..d { + // block_sigma: (chi_l, chi_r) + let block = phys_block(t, sigma, chi_r); + // conj(block)^T * transfer * block + let conj_block_t = block.conjugate().transpose(); + let tmp = &conj_block_t * &transfer * █ + new_transfer += tmp; + } + transfer = new_transfer; + } + + // Final transfer is 1x1 + transfer[(0, 0)].re + } + + /// Compute `` where O is a product of per-site 2x2 operators. + /// + /// `ops` maps site index -> 2x2 matrix. Sites not in `ops` get identity. + /// Returns the complex expectation value. + #[must_use] + pub fn expectation_product(&self, ops: &[(usize, DMatrix)]) -> Complex64 { + let d = self.phys_dim; + let mut transfer = DMatrix::from_element(1, 1, Complex64::new(1.0, 0.0)); + + // Build a lookup for which sites have operators + let mut site_ops: Vec>> = vec![None; self.num_sites]; + for (site, op) in ops { + site_ops[*site] = Some(op); + } + + for (q, site_op) in site_ops.iter().enumerate() { + let chi_r = self.bond_dims[q + 1]; + let t = &self.tensors[q]; + + let mut new_transfer = DMatrix::zeros(chi_r, chi_r); + + if let Some(op) = site_op { + // at this site + // new_transfer = sum_{sigma_bra, sigma_ket} conj(A[sigma_bra])^T * transfer * A[sigma_ket] * O[sigma_bra, sigma_ket] + for sigma_bra in 0..d { + let bra_block = phys_block(t, sigma_bra, chi_r); + let conj_bra_t = bra_block.conjugate().transpose(); + for sigma_ket in 0..d { + let o_val = op[(sigma_bra, sigma_ket)]; + if o_val.norm() < 1e-15 { + continue; + } + let ket_block = phys_block(t, sigma_ket, chi_r); + let tmp = &conj_bra_t * &transfer * &ket_block; + new_transfer += tmp * o_val; + } + } + } else { + // Identity at this site (same as norm_squared) + for sigma in 0..d { + let block = phys_block(t, sigma, chi_r); + let conj_block_t = block.conjugate().transpose(); + let tmp = &conj_block_t * &transfer * █ + new_transfer += tmp; + } + } + + transfer = new_transfer; + } + + transfer[(0, 0)] + } + + /// Normalize the MPS so that ` = 1`. + pub fn normalize(&mut self) { + if self.tensors.is_empty() { + return; + } + let norm_sq = self.norm_squared(); + if norm_sq > 0.0 { + let inv_norm = Complex64::new(1.0 / norm_sq.sqrt(), 0.0); + self.tensors[0] *= inv_norm; + } + } + + /// Extract the amplitude for a given computational basis state. + /// + /// `basis_state[i]` is the physical index (0 or 1) at site `i`. + /// + /// # Panics + /// + /// Panics if `basis_state.len() != self.num_sites`. + #[must_use] + pub fn amplitude(&self, basis_state: &[u8]) -> Complex64 { + assert_eq!(basis_state.len(), self.num_sites); + + // Contract: A[0]^{s_0} * A[1]^{s_1} * ... * A[N-1]^{s_{N-1}} + // Each A[i]^{s_i} is a (chi_l, chi_r) matrix. Product is a 1x1 scalar. + let mut result = DMatrix::from_element(1, 1, Complex64::new(1.0, 0.0)); + for (q, &sigma) in basis_state.iter().enumerate() { + let sigma = sigma as usize; + let chi_r = self.bond_dims[q + 1]; + let block = phys_block(&self.tensors[q], sigma, chi_r); + result = &result * █ + } + result[(0, 0)] + } + + /// Compute the full state vector (2^N complex amplitudes). + /// + /// Only for testing on small systems. + /// When `parallel` is enabled in the config, amplitude computations run on + /// rayon's thread pool. + /// + /// # Panics + /// + /// Panics if `num_sites > 20`. + #[must_use] + pub fn state_vector(&self) -> Vec { + assert!( + self.num_sites <= 20, + "state_vector is only for small systems (N <= 20)" + ); + let dim = 1 << self.num_sites; + let n = self.num_sites; + + let to_basis = |idx: usize| -> Vec { + (0..n) + .map(|q| u8::try_from((idx >> (n - 1 - q)) & 1).unwrap()) + .collect() + }; + + if self.config.parallel { + (0..dim) + .into_par_iter() + .map(|idx| self.amplitude(&to_basis(idx))) + .collect() + } else { + (0..dim).map(|idx| self.amplitude(&to_basis(idx))).collect() + } + } + + /// Add two MPS of the same structure (direct sum of bond spaces). + /// + /// The result has bond dimension `chi_self + chi_other` at each internal bond. + /// Should be followed by SVD truncation (e.g. via `left_canonicalize` + truncate). + /// + /// # Panics + /// + /// Panics if `self` and `other` differ in `num_sites` or `phys_dim`. + #[must_use] + pub fn add(&self, other: &Self) -> Self { + assert_eq!(self.num_sites, other.num_sites); + assert_eq!(self.phys_dim, other.phys_dim); + let d = self.phys_dim; + let n = self.num_sites; + + let mut new_bond_dims = vec![1; n + 1]; + for (new_bd, (bd_s, bd_o)) in new_bond_dims[1..n].iter_mut().zip( + self.bond_dims[1..n] + .iter() + .zip(other.bond_dims[1..n].iter()), + ) { + *new_bd = bd_s + bd_o; + } + + let mut new_tensors = Vec::with_capacity(n); + for q in 0..n { + let chi_l_s = self.bond_dims[q]; + let chi_r_s = self.bond_dims[q + 1]; + let chi_l_o = other.bond_dims[q]; + let chi_r_o = other.bond_dims[q + 1]; + let chi_l_new = new_bond_dims[q]; + let chi_r_new = new_bond_dims[q + 1]; + + let mut t = DMatrix::zeros(chi_l_new, d * chi_r_new); + + for sigma in 0..d { + // Place self's block in top-left + let block_s = phys_block(&self.tensors[q], sigma, chi_r_s); + for i in 0..chi_l_s { + for j in 0..chi_r_s { + t[(i, sigma * chi_r_new + j)] = block_s[(i, j)]; + } + } + + // Place other's block in bottom-right (or add at boundaries) + let block_o = phys_block(&other.tensors[q], sigma, chi_r_o); + let row_offset = if q == 0 { 0 } else { chi_l_s }; + let col_offset = if q == n - 1 { 0 } else { chi_r_s }; + for i in 0..chi_l_o { + for j in 0..chi_r_o { + t[(row_offset + i, sigma * chi_r_new + col_offset + j)] += block_o[(i, j)]; + } + } + } + + new_tensors.push(t); + } + + Self { + num_sites: n, + phys_dim: d, + tensors: new_tensors, + bond_dims: new_bond_dims, + config: self.config.clone(), + truncation_error: self.truncation_error.max(other.truncation_error), + bond_cap_hits: self.bond_cap_hits + other.bond_cap_hits, + } + } + + /// Access the internal tensors. + #[must_use] + pub fn tensors(&self) -> &[DMatrix] { + &self.tensors + } + + /// Mutable access to the internal tensors. + pub fn tensors_mut(&mut self) -> &mut [DMatrix] { + &mut self.tensors + } + + /// Access the bond dimensions (for testing). + #[must_use] + pub fn bond_dims(&self) -> &[usize] { + &self.bond_dims + } + + /// Left-canonicalize the entire MPS. + pub fn left_canonicalize(&mut self) { + canon::left_canonicalize_all(&mut self.tensors, &mut self.bond_dims, self.phys_dim); + } + + /// Right-canonicalize the entire MPS. + pub fn right_canonicalize(&mut self) { + canon::right_canonicalize_all(&mut self.tensors, &mut self.bond_dims, self.phys_dim); + } + + /// Compress the MPS by SVD truncation at each bond. + /// + /// Left-canonicalizes first, then sweeps right-to-left performing SVD + /// truncation at each bond to enforce `max_bond_dim` and `svd_cutoff`. + pub fn compress(&mut self) { + if self.num_sites <= 1 { + return; + } + + // Skip if all interior bonds are already bd=1 (product state). + if self.bond_dims[1..self.num_sites].iter().all(|&bd| bd <= 1) { + return; + } + + // Left-canonicalize + self.left_canonicalize(); + + // Sweep right to left: at each bond, reshape the site tensor into + // (chi_l * d, chi_r), do truncated SVD, absorb U*S into left neighbor. + let d = self.phys_dim; + for q in (1..self.num_sites).rev() { + let chi_l = self.bond_dims[q]; + + // Reshape site q from (chi_l, d * chi_r) to (chi_l, d * chi_r) -- already in this form. + // But we want to split the left bond, so transpose the grouping: + // Reshape to (chi_l, d * chi_r) and do SVD to split as (chi_l, new_chi) * (new_chi, d * chi_r). + let matrix = &self.tensors[q]; + if let Ok((u, svt, disc, hit)) = svd::truncated_svd_right_absorb_with_error( + matrix, + self.config.max_bond_dim, + self.config.svd_cutoff, + self.config.max_truncation_error, + ) { + self.record_truncation(disc, hit); + let new_chi = u.ncols(); + if new_chi < chi_l { + // U: (chi_l, new_chi) -- absorb into left neighbor + // SVt: (new_chi, d * chi_r) -- new site q tensor + self.tensors[q] = svt; + self.bond_dims[q] = new_chi; + + // Absorb U into tensors[q-1]: multiply each physical block by U + let chi_l_prev = self.bond_dims[q - 1]; + let old_chi_r_prev = chi_l; // was bond_dims[q] before update + let mut new_prev = DMatrix::zeros(chi_l_prev, d * new_chi); + for sigma in 0..d { + let prev_block = + tensor::phys_block(&self.tensors[q - 1], sigma, old_chi_r_prev); + let absorbed = &prev_block * &u; + for i in 0..chi_l_prev { + for j in 0..new_chi { + new_prev[(i, sigma * new_chi + j)] = absorbed[(i, j)]; + } + } + } + self.tensors[q - 1] = new_prev; + } + } + } + } +} + +impl Clone for Mps { + fn clone(&self) -> Self { + Self { + num_sites: self.num_sites, + phys_dim: self.phys_dim, + tensors: self.tensors.clone(), + bond_dims: self.bond_dims.clone(), + config: self.config.clone(), + truncation_error: self.truncation_error, + bond_cap_hits: self.bond_cap_hits, + } + } +} + +#[cfg(test)] +mod tests { + use super::*; + use approx::assert_relative_eq; + + #[test] + fn test_new_is_all_zeros_state() { + let mps = Mps::new(3, MpsConfig::default()); + assert_eq!(mps.num_sites(), 3); + assert_relative_eq!(mps.amplitude(&[0, 0, 0]).re, 1.0, epsilon = 1e-10); + assert_relative_eq!(mps.amplitude(&[0, 0, 1]).norm(), 0.0, epsilon = 1e-10); + assert_relative_eq!(mps.amplitude(&[1, 0, 0]).norm(), 0.0, epsilon = 1e-10); + } + + #[test] + fn test_norm_of_initial_state() { + let mps = Mps::new(4, MpsConfig::default()); + assert_relative_eq!(mps.norm_squared(), 1.0, epsilon = 1e-10); + } + + #[test] + fn test_single_site_x_gate() { + let mut mps = Mps::new(2, MpsConfig::default()); + // X gate on site 0: |00> -> |10> + let x = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + mps.apply_one_site_gate(0, &x).unwrap(); + assert_relative_eq!(mps.amplitude(&[1, 0]).re, 1.0, epsilon = 1e-10); + assert_relative_eq!(mps.amplitude(&[0, 0]).norm(), 0.0, epsilon = 1e-10); + assert_relative_eq!(mps.norm_squared(), 1.0, epsilon = 1e-10); + } + + #[test] + fn test_hadamard_gate() { + let mut mps = Mps::new(1, MpsConfig::default()); + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + let h = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(-inv_sqrt2, 0.0), + ], + ); + mps.apply_one_site_gate(0, &h).unwrap(); + // |+> = (|0> + |1>) / sqrt(2) + assert_relative_eq!(mps.amplitude(&[0]).re, inv_sqrt2, epsilon = 1e-10); + assert_relative_eq!(mps.amplitude(&[1]).re, inv_sqrt2, epsilon = 1e-10); + assert_relative_eq!(mps.norm_squared(), 1.0, epsilon = 1e-10); + } + + #[test] + fn test_diagonal_gate() { + let mut mps = Mps::new(1, MpsConfig::default()); + // First apply H to get |+> + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + let h = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(-inv_sqrt2, 0.0), + ], + ); + mps.apply_one_site_gate(0, &h).unwrap(); + // Apply Z = diag(1, -1) + mps.apply_diagonal_one_site(0, &[Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)]) + .unwrap(); + // Should get |->: (|0> - |1>) / sqrt(2) + assert_relative_eq!(mps.amplitude(&[0]).re, inv_sqrt2, epsilon = 1e-10); + assert_relative_eq!(mps.amplitude(&[1]).re, -inv_sqrt2, epsilon = 1e-10); + } + + #[test] + fn test_cnot_gate() { + let mut mps = Mps::new(2, MpsConfig::default()); + // Apply X to site 0: |00> -> |10> + let x = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + mps.apply_one_site_gate(0, &x).unwrap(); + + // Apply CNOT (control=0, target=1): |10> -> |11> + let mut cnot = DMatrix::zeros(4, 4); + cnot[(0, 0)] = Complex64::new(1.0, 0.0); // |00> -> |00> + cnot[(1, 1)] = Complex64::new(1.0, 0.0); // |01> -> |01> + cnot[(3, 2)] = Complex64::new(1.0, 0.0); // |10> -> |11> + cnot[(2, 3)] = Complex64::new(1.0, 0.0); // |11> -> |10> + mps.apply_two_site_gate(0, &cnot).unwrap(); + + assert_relative_eq!(mps.amplitude(&[1, 1]).re, 1.0, epsilon = 1e-10); + assert_relative_eq!(mps.amplitude(&[0, 0]).norm(), 0.0, epsilon = 1e-10); + assert_relative_eq!(mps.amplitude(&[1, 0]).norm(), 0.0, epsilon = 1e-10); + assert_relative_eq!(mps.norm_squared(), 1.0, epsilon = 1e-10); + } + + #[test] + fn test_bell_state() { + let mut mps = Mps::new(2, MpsConfig::default()); + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + + // H on site 0 + let h = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(-inv_sqrt2, 0.0), + ], + ); + mps.apply_one_site_gate(0, &h).unwrap(); + + // CNOT + let mut cnot = DMatrix::zeros(4, 4); + cnot[(0, 0)] = Complex64::new(1.0, 0.0); + cnot[(1, 1)] = Complex64::new(1.0, 0.0); + cnot[(3, 2)] = Complex64::new(1.0, 0.0); + cnot[(2, 3)] = Complex64::new(1.0, 0.0); + mps.apply_two_site_gate(0, &cnot).unwrap(); + + // Bell state: (|00> + |11>) / sqrt(2) + assert_relative_eq!(mps.amplitude(&[0, 0]).re, inv_sqrt2, epsilon = 1e-10); + assert_relative_eq!(mps.amplitude(&[1, 1]).re, inv_sqrt2, epsilon = 1e-10); + assert_relative_eq!(mps.amplitude(&[0, 1]).norm(), 0.0, epsilon = 1e-10); + assert_relative_eq!(mps.amplitude(&[1, 0]).norm(), 0.0, epsilon = 1e-10); + assert_relative_eq!(mps.norm_squared(), 1.0, epsilon = 1e-10); + assert_eq!(mps.bond_dim(1), 2); // Bell state needs bond dim 2 + } + + #[test] + fn test_state_vector() { + let mut mps = Mps::new(2, MpsConfig::default()); + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + let h = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(-inv_sqrt2, 0.0), + ], + ); + mps.apply_one_site_gate(0, &h).unwrap(); + let sv = mps.state_vector(); + // |+0> = (|00> + |10>) / sqrt(2) + assert_eq!(sv.len(), 4); + assert_relative_eq!(sv[0].re, inv_sqrt2, epsilon = 1e-10); // |00> + assert_relative_eq!(sv[1].norm(), 0.0, epsilon = 1e-10); // |01> + assert_relative_eq!(sv[2].re, inv_sqrt2, epsilon = 1e-10); // |10> + assert_relative_eq!(sv[3].norm(), 0.0, epsilon = 1e-10); // |11> + } + + #[test] + fn test_scale() { + let mut mps = Mps::new(2, MpsConfig::default()); + mps.scale(Complex64::new(0.0, 1.0)); // multiply by i + assert_relative_eq!(mps.amplitude(&[0, 0]).im, 1.0, epsilon = 1e-10); + assert_relative_eq!(mps.norm_squared(), 1.0, epsilon = 1e-10); + } + + #[test] + fn test_mps_add() { + // |00> + |11> (unnormalized) + let mps0 = Mps::new(2, MpsConfig::default()); // |00> + + let mut mps1 = Mps::new(2, MpsConfig::default()); + let x = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + mps1.apply_one_site_gate(0, &x).unwrap(); + mps1.apply_one_site_gate(1, &x).unwrap(); + // mps1 = |11> + + let sum = mps0.add(&mps1); + // Should be |00> + |11> + assert_relative_eq!(sum.amplitude(&[0, 0]).re, 1.0, epsilon = 1e-10); + assert_relative_eq!(sum.amplitude(&[1, 1]).re, 1.0, epsilon = 1e-10); + assert_relative_eq!(sum.amplitude(&[0, 1]).norm(), 0.0, epsilon = 1e-10); + assert_relative_eq!(sum.amplitude(&[1, 0]).norm(), 0.0, epsilon = 1e-10); + assert_relative_eq!(sum.norm_squared(), 2.0, epsilon = 1e-10); + } + + #[test] + fn test_two_site_gate_preserves_norm() { + // Build an entangled 4-qubit MPS, then apply a two-site gate. + // The norm should be preserved. + let mut mps = Mps::new(4, MpsConfig::default()); + + // Create entanglement: H(0), CNOT(0,1), H(2), CNOT(2,3) + let h = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(-std::f64::consts::FRAC_1_SQRT_2, 0.0), + ], + ); + let cnot = DMatrix::from_row_slice( + 4, + 4, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let swap = DMatrix::from_row_slice( + 4, + 4, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + ], + ); + + mps.apply_one_site_gate(0, &h).unwrap(); + mps.apply_two_site_gate(0, &cnot).unwrap(); + mps.apply_one_site_gate(2, &h).unwrap(); + mps.apply_two_site_gate(2, &cnot).unwrap(); + + let norm_before = mps.norm_squared(); + assert_relative_eq!(norm_before, 1.0, epsilon = 1e-10); + + // Apply various two-site gates and check norm + mps.apply_two_site_gate(1, &cnot).unwrap(); + assert_relative_eq!(mps.norm_squared(), 1.0, epsilon = 1e-10); // "CNOT on (1,2)"); + + mps.apply_two_site_gate(0, &swap).unwrap(); + assert_relative_eq!(mps.norm_squared(), 1.0, epsilon = 1e-10); // "SWAP on (0,1)"); + + // Long-range CNOT via SWAP chain + mps.apply_long_range_two_site_gate(0, 3, &cnot).unwrap(); + assert_relative_eq!(mps.norm_squared(), 1.0, epsilon = 1e-10); // "Long-range CNOT(0,3)"); + + mps.apply_long_range_two_site_gate(0, 2, &swap).unwrap(); + assert_relative_eq!(mps.norm_squared(), 1.0, epsilon = 1e-10); + } + + #[test] + fn test_long_range_cnot_state_vector() { + // Apply CNOT(0, 2) to H(0)|000⟩ via the MPO approach + // and compare to building the exact state with adjacent gates. + let c0 = Complex64::new(0.0, 0.0); + let c1 = Complex64::new(1.0, 0.0); + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + let h = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(-inv_sqrt2, 0.0), + ], + ); + let cnot = DMatrix::from_row_slice( + 4, + 4, + &[ + c1, c0, c0, c0, c0, c1, c0, c0, c0, c0, c0, c1, c0, c0, c1, c0, + ], + ); + + // Method 1: long-range CNOT(0, 2) via MPO + let mut mps1 = Mps::new(3, MpsConfig::default()); + mps1.apply_one_site_gate(0, &h).unwrap(); + mps1.apply_long_range_two_site_gate(0, 2, &cnot).unwrap(); + let sv1 = mps1.state_vector(); + + // Method 2: build exact state manually + // H(0)|000⟩ = (|000⟩ + |100⟩) / sqrt(2) + // CNOT(0,2)(|000⟩ + |100⟩)/sqrt(2) = (|000⟩ + |101⟩)/sqrt(2) + // State vector ordering: MSB-first, so |000⟩ = idx 0, |101⟩ = idx 5 + assert_relative_eq!(sv1[0].re, inv_sqrt2, epsilon = 1e-8); + assert_relative_eq!(sv1[5].re, inv_sqrt2, epsilon = 1e-8); + for (i, amp) in sv1.iter().enumerate().take(8) { + if i != 0 && i != 5 { + assert_relative_eq!(amp.norm(), 0.0, epsilon = 1e-8); + } + } + } + + #[test] + fn test_long_range_cnot_entangled() { + // Apply CNOT(0, 3) on a 4-qubit state that's already entangled. + // Compare MPO approach to building reference via adjacent gates only. + let c0 = Complex64::new(0.0, 0.0); + let c1 = Complex64::new(1.0, 0.0); + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + let h = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(-inv_sqrt2, 0.0), + ], + ); + let cnot = DMatrix::from_row_slice( + 4, + 4, + &[ + c1, c0, c0, c0, c0, c1, c0, c0, c0, c0, c0, c1, c0, c0, c1, c0, + ], + ); + let swap = DMatrix::from_row_slice( + 4, + 4, + &[ + c1, c0, c0, c0, c0, c0, c1, c0, c0, c1, c0, c0, c0, c0, c0, c1, + ], + ); + + // Build entangled state: H(0), CNOT(0,1), H(2), CNOT(2,3) + // Then apply CNOT(0, 3) via MPO + let mut mps_mpo = Mps::new(4, MpsConfig::default()); + mps_mpo.apply_one_site_gate(0, &h).unwrap(); + mps_mpo.apply_two_site_gate(0, &cnot).unwrap(); + mps_mpo.apply_one_site_gate(2, &h).unwrap(); + mps_mpo.apply_two_site_gate(2, &cnot).unwrap(); + mps_mpo.apply_long_range_two_site_gate(0, 3, &cnot).unwrap(); + let sv_mpo = mps_mpo.state_vector(); + + // Reference: same state, CNOT(0, 3) via manual SWAP chain + let mut mps_ref = Mps::new(4, MpsConfig::default()); + mps_ref.apply_one_site_gate(0, &h).unwrap(); + mps_ref.apply_two_site_gate(0, &cnot).unwrap(); + mps_ref.apply_one_site_gate(2, &h).unwrap(); + mps_ref.apply_two_site_gate(2, &cnot).unwrap(); + // Manual SWAP chain for CNOT(0, 3) + mps_ref.apply_two_site_gate(2, &swap).unwrap(); // SWAP(2,3) + mps_ref.apply_two_site_gate(1, &swap).unwrap(); // SWAP(1,2) + mps_ref.apply_two_site_gate(0, &cnot).unwrap(); // CNOT(0,1) [was q3] + mps_ref.apply_two_site_gate(1, &swap).unwrap(); // SWAP back + mps_ref.apply_two_site_gate(2, &swap).unwrap(); // SWAP back + let sv_ref = mps_ref.state_vector(); + + // Check overlap + let overlap: Complex64 = sv_mpo + .iter() + .zip(sv_ref.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + assert_relative_eq!(overlap.norm_sqr(), 1.0, epsilon = 1e-6); + } + + #[test] + fn test_long_range_cnot_hi_ctrl() { + // Test with high-qubit control CNOT (target < control) + let c0 = Complex64::new(0.0, 0.0); + let c1 = Complex64::new(1.0, 0.0); + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + let h = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(-inv_sqrt2, 0.0), + ], + ); + // CNOT with hi-index qubit as control + let cnot_hi = DMatrix::from_row_slice( + 4, + 4, + &[ + c1, c0, c0, c0, c0, c0, c0, c1, c0, c0, c1, c0, c0, c1, c0, c0, + ], + ); + let swap = DMatrix::from_row_slice( + 4, + 4, + &[ + c1, c0, c0, c0, c0, c0, c1, c0, c0, c1, c0, c0, c0, c0, c0, c1, + ], + ); + + // H(2), CNOT_hi(0, 2) on 3-qubit MPS + // CNOT_hi: control=qubit 2, target=qubit 0 + let mut mps_mpo = Mps::new(3, MpsConfig::default()); + mps_mpo.apply_one_site_gate(2, &h).unwrap(); + mps_mpo + .apply_long_range_two_site_gate(0, 2, &cnot_hi) + .unwrap(); + let sv_mpo = mps_mpo.state_vector(); + + // Reference via SWAP chain + let mut mps_ref = Mps::new(3, MpsConfig::default()); + mps_ref.apply_one_site_gate(2, &h).unwrap(); + mps_ref.apply_two_site_gate(1, &swap).unwrap(); + mps_ref.apply_two_site_gate(0, &cnot_hi).unwrap(); + mps_ref.apply_two_site_gate(1, &swap).unwrap(); + let sv_ref = mps_ref.state_vector(); + + let overlap: Complex64 = sv_mpo + .iter() + .zip(sv_ref.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + assert_relative_eq!(overlap.norm_sqr(), 1.0, epsilon = 1e-6); + } + + #[test] + fn test_long_range_cnot_cascade() { + // Test the pattern from non_clifford.rs: multiple long-range CNOTs + let c0 = Complex64::new(0.0, 0.0); + let c1 = Complex64::new(1.0, 0.0); + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + let h = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(inv_sqrt2, 0.0), + Complex64::new(-inv_sqrt2, 0.0), + ], + ); + let cnot_lo = DMatrix::from_row_slice( + 4, + 4, + &[ + c1, c0, c0, c0, c0, c1, c0, c0, c0, c0, c0, c1, c0, c0, c1, c0, + ], + ); + let rx_gate = { + let theta = 0.5_f64; + let c = Complex64::new(theta.cos(), 0.0); + let s = Complex64::new(0.0, -theta.sin()); + DMatrix::from_row_slice(2, 2, &[c, s, s, c]) + }; + + // H on all, then CNOT cascade (0→1, 0→3), RX(0), reverse CNOT + let mut mps_mpo = Mps::new(4, MpsConfig::default()); + for q in 0..4 { + mps_mpo.apply_one_site_gate(q, &h).unwrap(); + } + mps_mpo.apply_two_site_gate(0, &cnot_lo).unwrap(); + mps_mpo + .apply_long_range_two_site_gate(0, 3, &cnot_lo) + .unwrap(); + mps_mpo.apply_one_site_gate(0, &rx_gate).unwrap(); + mps_mpo + .apply_long_range_two_site_gate(0, 3, &cnot_lo) + .unwrap(); + mps_mpo.apply_two_site_gate(0, &cnot_lo).unwrap(); + let sv_mpo = mps_mpo.state_vector(); + + // Reference: same but use SWAP chains for long-range + let swap = DMatrix::from_row_slice( + 4, + 4, + &[ + c1, c0, c0, c0, c0, c0, c1, c0, c0, c1, c0, c0, c0, c0, c0, c1, + ], + ); + let mut mps_ref = Mps::new(4, MpsConfig::default()); + for q in 0..4 { + mps_ref.apply_one_site_gate(q, &h).unwrap(); + } + mps_ref.apply_two_site_gate(0, &cnot_lo).unwrap(); + // SWAP chain for CNOT(0,3) + mps_ref.apply_two_site_gate(2, &swap).unwrap(); + mps_ref.apply_two_site_gate(1, &swap).unwrap(); + mps_ref.apply_two_site_gate(0, &cnot_lo).unwrap(); + mps_ref.apply_two_site_gate(1, &swap).unwrap(); + mps_ref.apply_two_site_gate(2, &swap).unwrap(); + mps_ref.apply_one_site_gate(0, &rx_gate).unwrap(); + // SWAP chain for CNOT(0,3) again + mps_ref.apply_two_site_gate(2, &swap).unwrap(); + mps_ref.apply_two_site_gate(1, &swap).unwrap(); + mps_ref.apply_two_site_gate(0, &cnot_lo).unwrap(); + mps_ref.apply_two_site_gate(1, &swap).unwrap(); + mps_ref.apply_two_site_gate(2, &swap).unwrap(); + mps_ref.apply_two_site_gate(0, &cnot_lo).unwrap(); + let sv_ref = mps_ref.state_vector(); + + let overlap: Complex64 = sv_mpo + .iter() + .zip(sv_ref.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + assert_relative_eq!(overlap.norm_sqr(), 1.0, epsilon = 1e-4); + } + + #[test] + fn test_multi_site_rotation_preserves_norm() { + // Reproduce the Stabilizer multi-site rotation: + // H(0), H(2), CNOT(0,2), RX(0), CNOT(0,2), H(0), H(2) + let mut mps = Mps::new(4, MpsConfig::default()); + + let h = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(-std::f64::consts::FRAC_1_SQRT_2, 0.0), + ], + ); + let cnot = DMatrix::from_row_slice( + 4, + 4, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let rx = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.9239, 0.0), + Complex64::new(0.0, -0.3827), + Complex64::new(0.0, -0.3827), + Complex64::new(0.9239, 0.0), + ], + ); + + // Build entangled state + mps.apply_one_site_gate(0, &h).unwrap(); + mps.apply_two_site_gate(0, &cnot).unwrap(); + mps.apply_one_site_gate(2, &h).unwrap(); + mps.apply_two_site_gate(2, &cnot).unwrap(); + assert_relative_eq!(mps.norm_squared(), 1.0, epsilon = 1e-10); + + // Multi-site Z rotation on sites {0, 2} + mps.apply_one_site_gate(0, &h).unwrap(); + mps.apply_one_site_gate(2, &h).unwrap(); + mps.apply_long_range_two_site_gate(0, 2, &cnot).unwrap(); + let norm_mid = mps.norm_squared(); + mps.apply_one_site_gate(0, &rx).unwrap(); + mps.apply_long_range_two_site_gate(0, 2, &cnot).unwrap(); + mps.apply_one_site_gate(0, &h).unwrap(); + mps.apply_one_site_gate(2, &h).unwrap(); + + eprintln!( + "norm mid-cascade: {norm_mid:.10}, after: {:.10}", + mps.norm_squared() + ); + assert_relative_eq!(mps.norm_squared(), 1.0, epsilon = 1e-3); + } +} diff --git a/exp/pecos-stab-tn/src/mps/canon.rs b/exp/pecos-stab-tn/src/mps/canon.rs new file mode 100644 index 000000000..19df73c41 --- /dev/null +++ b/exp/pecos-stab-tn/src/mps/canon.rs @@ -0,0 +1,149 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! MPS canonicalization via QR decomposition. +//! +//! Left-canonical form: each site tensor A[i] satisfies `sum_sigma` A[sigma]^dagger A[sigma] = I. +//! Right-canonical form: each site tensor B[i] satisfies `sum_sigma` B[sigma] B[sigma]^dagger = I. + +use super::tensor::{reshape_left_group, reshape_left_ungroup}; +use nalgebra::DMatrix; +use num_complex::Complex64; + +/// Left-canonicalize a single site by QR decomposition. +/// +/// Takes the site tensor at position `q` in `(chi_l, d * chi_r)` format, +/// reshapes to `(chi_l * d, chi_r)`, performs thin QR, stores Q back as the +/// new site tensor, and absorbs R into the next site's tensor. +/// +/// Returns the new bond dimension between sites q and q+1. +/// +/// # Panics +/// +/// Panics if `q >= tensors.len() - 1` (cannot left-canonicalize the last site). +pub fn left_canonicalize_site( + tensors: &mut [DMatrix], + bond_dims: &mut [usize], + q: usize, + d: usize, +) -> usize { + let num_sites = tensors.len(); + assert!(q < num_sites - 1, "cannot left-canonicalize the last site"); + + let chi_l = bond_dims[q]; + let chi_r = bond_dims[q + 1]; + + // Reshape to (chi_l * d, chi_r) for QR + let grouped = reshape_left_group(&tensors[q], chi_l, d, chi_r); + let qr = grouped.qr(); + let q_mat = qr.q(); + let r_mat = qr.r(); + + // New bond dimension = min(chi_l * d, chi_r) -- rank of R + let new_chi = q_mat.ncols(); + bond_dims[q + 1] = new_chi; + + // Store Q as new site tensor: reshape (chi_l * d, new_chi) -> (chi_l, d * new_chi) + tensors[q] = reshape_left_ungroup(&q_mat, chi_l, d, new_chi); + + // Absorb R into next site: new_next = R * old_next + // R: (new_chi, chi_r), next tensor: (chi_r, d * chi_r_next) -> needs reshape + let next = &tensors[q + 1]; + // Reshape next to (chi_r, d * chi_r_next) -- it already is in this form + // but chi_r might have been the old bond dim. The matrix R has chi_r columns. + // next has chi_r rows, d * chi_r_next columns. + let absorbed = &r_mat * next; + tensors[q + 1] = absorbed; + + new_chi +} + +/// Right-canonicalize a single site by LQ decomposition. +/// +/// Takes the site tensor at position `q`, reshapes to `(chi_l, d * chi_r)`, +/// performs LQ (via QR of transpose), stores Q back as the site tensor, +/// and absorbs L into the previous site's tensor. +/// +/// Returns the new bond dimension between sites q-1 and q. +/// +/// # Panics +/// +/// Panics if `q == 0` (cannot right-canonicalize the first site). +pub fn right_canonicalize_site( + tensors: &mut [DMatrix], + bond_dims: &mut [usize], + q: usize, + d: usize, +) -> usize { + assert!(q > 0, "cannot right-canonicalize the first site"); + + let chi_l = bond_dims[q]; + + // LQ decomposition via QR of transpose: A^T = Q R -> A = R^T Q^T = L Q + let at = tensors[q].transpose(); + let qr = at.qr(); + // Q^T gives us the right factor, R^T gives us the left factor + let q_mat_t = qr.q().transpose(); // shape: (new_chi, d * chi_r) -- but need to verify + let l_mat = qr.r().transpose(); // shape: (chi_l, new_chi) + + let new_chi = q_mat_t.nrows(); + bond_dims[q] = new_chi; + + // Store Q^T as the new site tensor: (new_chi, d * chi_r) + // We need to reshape this back to proper site tensor format + tensors[q] = q_mat_t; + + // Absorb L into previous site + // Previous site: (chi_l_prev, d * chi_l) -- the last chi_l columns per physical block + // L: (chi_l, new_chi) + // We need: new_prev[alpha_l_prev, sigma * new_chi + alpha_new] = + // sum_{alpha_l} prev[alpha_l_prev, sigma * chi_l + alpha_l] * L[alpha_l, alpha_new] + let chi_l_prev = bond_dims[q - 1]; + let prev = &tensors[q - 1]; + let mut new_prev = DMatrix::zeros(chi_l_prev, d * new_chi); + for sigma in 0..d { + let prev_block = prev.columns(sigma * chi_l, chi_l).clone_owned(); + let absorbed_block = &prev_block * &l_mat; + for i in 0..chi_l_prev { + for j in 0..new_chi { + new_prev[(i, sigma * new_chi + j)] = absorbed_block[(i, j)]; + } + } + } + tensors[q - 1] = new_prev; + + new_chi +} + +/// Put the entire MPS in left-canonical form by sweeping left to right. +pub fn left_canonicalize_all( + tensors: &mut [DMatrix], + bond_dims: &mut [usize], + d: usize, +) { + let n = tensors.len(); + for q in 0..n - 1 { + left_canonicalize_site(tensors, bond_dims, q, d); + } +} + +/// Put the entire MPS in right-canonical form by sweeping right to left. +pub fn right_canonicalize_all( + tensors: &mut [DMatrix], + bond_dims: &mut [usize], + d: usize, +) { + let n = tensors.len(); + for q in (1..n).rev() { + right_canonicalize_site(tensors, bond_dims, q, d); + } +} diff --git a/exp/pecos-stab-tn/src/mps/svd.rs b/exp/pecos-stab-tn/src/mps/svd.rs new file mode 100644 index 000000000..9a1ac9c0b --- /dev/null +++ b/exp/pecos-stab-tn/src/mps/svd.rs @@ -0,0 +1,551 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Truncated SVD for MPS bond compression. +//! +//! Provides both full SVD (via nalgebra) and randomized SVD for large matrices. +//! The randomized variant uses the Halko-Martinsson-Tropp algorithm (2011): +//! random projection -> QR -> small SVD, giving O(mnr) cost instead of +//! O(mn * min(m,n)) for the full SVD. + +use crate::errors::MpsError; +use nalgebra::{DMatrix, DVector, SVD}; +use num_complex::Complex64; + +/// Result of a truncated SVD. +pub struct TruncatedSvd { + /// Left singular vectors, shape (m, r). + pub u: DMatrix, + /// Singular values (r entries, descending order). + pub singular_values: Vec, + /// Right singular vectors (conjugate transpose), shape (r, n). + pub vt: DMatrix, + /// Relative weight of discarded singular values: + /// `sum(discarded_sv²) / sum(all_sv²)`. Zero if no truncation. + /// Approximates the 1-fidelity cost of this SVD step. + pub discarded_weight: f64, + /// True if the kept rank equals `max_rank` (i.e. the bond cap was binding). + /// Useful for detecting under-resolution in adaptive schemes. + pub hit_cap: bool, +} + +/// Perform truncated SVD on a complex matrix. +/// +/// Given matrix M of shape (m, n), computes M = U * diag(S) * V^dagger, +/// then keeps at most `max_rank` singular values that are above `cutoff`. +/// If `max_trunc_error` is Some, also stops when the relative discarded +/// weight (sum of discarded `s_i^2` / total) would exceed the budget. +/// +/// # Errors +/// +/// Returns [`MpsError::SvdFailed`] if nalgebra's SVD fails to produce U or V^T. +pub fn truncated_svd( + matrix: &DMatrix, + max_rank: usize, + cutoff: f64, +) -> Result { + truncated_svd_with_error(matrix, max_rank, cutoff, None) +} + +/// Perform truncated SVD with optional adaptive error budget. +/// +/// # Errors +/// +/// Returns [`MpsError::SvdFailed`] if nalgebra's SVD fails to produce U or V^T. +pub fn truncated_svd_with_error( + matrix: &DMatrix, + max_rank: usize, + cutoff: f64, + max_trunc_error: Option, +) -> Result { + let svd = SVD::new(matrix.clone(), true, true); + + let u_full = svd.u.ok_or(MpsError::SvdFailed)?; + let vt_full = svd.v_t.ok_or(MpsError::SvdFailed)?; + let svals: &DVector = &svd.singular_values; + + let rank = compute_rank(svals, max_rank, cutoff, max_trunc_error); + + let u_trunc = u_full.columns(0, rank).clone_owned(); + let vt_trunc = vt_full.rows(0, rank).clone_owned(); + let kept_svals: Vec = svals.iter().take(rank).copied().collect(); + let total_weight: f64 = svals.iter().map(|s| s * s).sum(); + let kept_weight: f64 = kept_svals.iter().map(|s| s * s).sum(); + let discarded_weight = if total_weight > 0.0 { + ((total_weight - kept_weight) / total_weight).max(0.0) + } else { + 0.0 + }; + + Ok(TruncatedSvd { + u: u_trunc, + singular_values: kept_svals, + vt: vt_trunc, + discarded_weight, + hit_cap: rank >= max_rank && svals.len() > max_rank, + }) +} + +/// Determine how many singular values to keep given truncation criteria. +fn compute_rank( + svals: &DVector, + max_rank: usize, + cutoff: f64, + max_trunc_error: Option, +) -> usize { + let n = svals.len(); + + // Start with all singular values that pass the hard criteria + let mut rank = 0; + for i in 0..n { + if i >= max_rank { + break; + } + if svals[i] < cutoff { + break; + } + rank += 1; + } + + // Apply adaptive error budget: reduce rank if discarded weight is within budget + if let Some(max_err) = max_trunc_error { + let total_weight: f64 = svals.iter().map(|s| s * s).sum(); + if total_weight > 0.0 { + // Walk backwards from rank, checking if we can drop more values + let mut discarded_weight = 0.0; + for i in (1..rank).rev() { + let candidate_discard = discarded_weight + svals[i] * svals[i]; + if candidate_discard / total_weight > max_err { + break; + } + discarded_weight = candidate_discard; + rank = i; + } + } + } + + // Keep at least 1 to avoid empty tensors + rank.max(1) +} + +/// Oversampling parameter for randomized SVD. +const RSVD_OVERSAMPLING: usize = 5; + +/// Minimum matrix dimension ratio (min(m,n) / `max_rank`) to trigger randomized SVD. +/// When the ratio exceeds this threshold, randomized SVD is used instead of full SVD. +const RSVD_THRESHOLD: usize = 4; + +/// Perform truncated SVD, automatically choosing between full and randomized. +/// +/// Uses randomized SVD when `max_rank * RSVD_THRESHOLD < min(m, n)`, +/// otherwise uses full SVD. +/// +/// # Errors +/// +/// Returns [`MpsError::SvdFailed`] if the underlying SVD fails to produce U or V^T. +pub fn truncated_svd_auto( + matrix: &DMatrix, + max_rank: usize, + cutoff: f64, +) -> Result { + truncated_svd_auto_with_error(matrix, max_rank, cutoff, None) +} + +/// Perform truncated SVD with error budget, auto-selecting algorithm. +/// +/// # Errors +/// +/// Returns [`MpsError::SvdFailed`] if the underlying SVD fails to produce U or V^T. +pub fn truncated_svd_auto_with_error( + matrix: &DMatrix, + max_rank: usize, + cutoff: f64, + max_trunc_error: Option, +) -> Result { + let m = matrix.nrows(); + let n = matrix.ncols(); + let min_dim = m.min(n); + + if max_rank * RSVD_THRESHOLD < min_dim && max_rank + RSVD_OVERSAMPLING < min_dim { + randomized_truncated_svd_with_error(matrix, max_rank, cutoff, max_trunc_error) + } else { + truncated_svd_with_error(matrix, max_rank, cutoff, max_trunc_error) + } +} + +/// Randomized truncated SVD using the Halko-Martinsson-Tropp algorithm. +/// +/// For an m×n matrix A with target rank r: +/// 1. Generate random sketch Ω (n × (r+p)) +/// 2. Y = A × Ω (m × (r+p)) +/// 3. Q, _ = QR(Y) (thin QR) +/// 4. B = Q^H × A ((r+p) × n) +/// 5. SVD(B) = Ũ Σ V^T +/// 6. U = Q × Ũ +/// +/// Cost: O(mn(r+p)) vs O(mn·min(m,n)) for full SVD. +fn randomized_truncated_svd_with_error( + matrix: &DMatrix, + max_rank: usize, + cutoff: f64, + max_trunc_error: Option, +) -> Result { + // f64 mantissa is 53 bits, so we extract top 53 bits and convert in two + // lossless u32->f64 steps to avoid clippy::cast_precision_loss. + const SCALE: f64 = 2.0 / 9_007_199_254_740_992.0; // 2 / 2^53 + + let m = matrix.nrows(); + let n = matrix.ncols(); + let sketch_cols = (max_rank + RSVD_OVERSAMPLING).min(m.min(n)); + + // Step 1: Generate random sketch matrix Ω (n × sketch_cols) + // Using a simple xorshift64 PRNG seeded deterministically from matrix dimensions. + // Deterministic seed means same matrix always gives same result. + let mut rng_state: u64 = 0x5DEE_CE66_D1A4_F87D ^ (m as u64 * 31 + n as u64 * 37); + let next_f64 = |state: &mut u64| -> f64 { + *state ^= *state << 13; + *state ^= *state >> 7; + *state ^= *state << 17; + // Map to uniform [-1, 1] (sub-Gaussian suffices for randomized SVD). + let top53 = *state >> 11; + let hi = (top53 >> 21) as u32; // upper 32 bits + let lo = (top53 & 0x1F_FFFF) as u32; // lower 21 bits + (f64::from(hi) * f64::from(1u32 << 21) + f64::from(lo)) * SCALE - 1.0 + }; + + let omega = DMatrix::from_fn(n, sketch_cols, |_i, _j| { + Complex64::new(next_f64(&mut rng_state), next_f64(&mut rng_state)) + }); + + // Step 2: Y = A × Ω (m × sketch_cols) + let y = matrix * ω + + // Step 3: Thin QR of Y + let qr = y.qr(); + let q = qr.q(); // m × min(m, sketch_cols) + let q_cols = q.ncols().min(sketch_cols); + let q_thin = q.columns(0, q_cols).clone_owned(); + + // Step 4: B = Q^H × A (q_cols × n) + let b = q_thin.adjoint() * matrix; + + // Step 5: Full SVD of the small matrix B + let svd_b = SVD::new(b, true, true); + let u_b = svd_b.u.ok_or(MpsError::SvdFailed)?; + let vt_b = svd_b.v_t.ok_or(MpsError::SvdFailed)?; + let svals: &DVector = &svd_b.singular_values; + + // Determine rank using same criteria as full SVD + let rank = compute_rank(svals, max_rank, cutoff, max_trunc_error); + + // Step 6: U = Q × Ũ_truncated + let u_b_trunc = u_b.columns(0, rank).clone_owned(); + let u = &q_thin * &u_b_trunc; + + let vt_trunc = vt_b.rows(0, rank).clone_owned(); + let kept_svals: Vec = svals.iter().take(rank).copied().collect(); + let total_weight: f64 = svals.iter().map(|s| s * s).sum(); + let kept_weight: f64 = kept_svals.iter().map(|s| s * s).sum(); + let discarded_weight = if total_weight > 0.0 { + ((total_weight - kept_weight) / total_weight).max(0.0) + } else { + 0.0 + }; + + Ok(TruncatedSvd { + u, + singular_values: kept_svals, + vt: vt_trunc, + discarded_weight, + hit_cap: rank >= max_rank && svals.len() > max_rank, + }) +} + +/// Perform truncated SVD and absorb singular values into the left matrix. +/// +/// Returns `(U * diag(S), V^dagger)` after truncation. +/// Automatically uses randomized SVD for large matrices with small target rank. +/// +/// # Errors +/// +/// Returns [`MpsError::SvdFailed`] if the underlying SVD fails to produce U or V^T. +pub fn truncated_svd_left_absorb( + matrix: &DMatrix, + max_rank: usize, + cutoff: f64, + max_trunc_error: Option, +) -> Result<(DMatrix, DMatrix), MpsError> { + let (us, vt, _, _) = + truncated_svd_left_absorb_with_error(matrix, max_rank, cutoff, max_trunc_error)?; + Ok((us, vt)) +} + +/// Like `truncated_svd_left_absorb` but also returns (`discarded_weight`, `hit_cap`). +/// +/// # Errors +/// +/// Returns [`MpsError::SvdFailed`] if the underlying SVD fails to produce U or V^T. +pub fn truncated_svd_left_absorb_with_error( + matrix: &DMatrix, + max_rank: usize, + cutoff: f64, + max_trunc_error: Option, +) -> Result<(DMatrix, DMatrix, f64, bool), MpsError> { + let result = truncated_svd_auto_with_error(matrix, max_rank, cutoff, max_trunc_error)?; + let mut u_scaled = result.u; + for (j, &sv) in result.singular_values.iter().enumerate() { + let scale = Complex64::new(sv, 0.0); + for i in 0..u_scaled.nrows() { + u_scaled[(i, j)] *= scale; + } + } + Ok((u_scaled, result.vt, result.discarded_weight, result.hit_cap)) +} + +/// Perform truncated SVD and absorb singular values into the right matrix. +/// +/// Returns `(U, diag(S) * V^dagger)` after truncation. +/// Automatically uses randomized SVD for large matrices with small target rank. +/// +/// # Errors +/// +/// Returns [`MpsError::SvdFailed`] if the underlying SVD fails to produce U or V^T. +pub fn truncated_svd_right_absorb( + matrix: &DMatrix, + max_rank: usize, + cutoff: f64, + max_trunc_error: Option, +) -> Result<(DMatrix, DMatrix), MpsError> { + let (u, svt, _, _) = + truncated_svd_right_absorb_with_error(matrix, max_rank, cutoff, max_trunc_error)?; + Ok((u, svt)) +} + +/// Like `truncated_svd_right_absorb` but also returns (`discarded_weight`, `hit_cap`). +/// +/// # Errors +/// +/// Returns [`MpsError::SvdFailed`] if the underlying SVD fails to produce U or V^T. +pub fn truncated_svd_right_absorb_with_error( + matrix: &DMatrix, + max_rank: usize, + cutoff: f64, + max_trunc_error: Option, +) -> Result<(DMatrix, DMatrix, f64, bool), MpsError> { + let result = truncated_svd_auto_with_error(matrix, max_rank, cutoff, max_trunc_error)?; + let mut svt = result.vt; + for (i, &sv) in result.singular_values.iter().enumerate() { + let scale = Complex64::new(sv, 0.0); + for j in 0..svt.ncols() { + svt[(i, j)] *= scale; + } + } + Ok((result.u, svt, result.discarded_weight, result.hit_cap)) +} + +#[cfg(test)] +mod tests { + use super::*; + use approx::assert_relative_eq; + + #[test] + fn test_truncated_svd_identity() { + let m = DMatrix::from_fn(3, 3, |i, j| { + if i == j { + Complex64::new(1.0, 0.0) + } else { + Complex64::new(0.0, 0.0) + } + }); + let result = truncated_svd(&m, 10, 1e-12).unwrap(); + assert_eq!(result.singular_values.len(), 3); + for sv in &result.singular_values { + assert_relative_eq!(*sv, 1.0, epsilon = 1e-10); + } + } + + #[test] + fn test_truncated_svd_rank_1() { + // Rank-1 matrix: outer product of [1, 0] and [1, 1] + let m = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let result = truncated_svd(&m, 10, 1e-12).unwrap(); + // Should have rank 1 (second singular value ~ 0) + assert_eq!(result.singular_values.len(), 1); + assert_relative_eq!(result.singular_values[0], 2.0_f64.sqrt(), epsilon = 1e-10); + } + + #[test] + fn test_truncated_svd_max_rank() { + let m = DMatrix::from_fn(4, 4, |i, j| { + if i == j { + Complex64::new(f64::from(u32::try_from(4 - i).unwrap()), 0.0) + } else { + Complex64::new(0.0, 0.0) + } + }); + let result = truncated_svd(&m, 2, 1e-12).unwrap(); + assert_eq!(result.singular_values.len(), 2); + assert_relative_eq!(result.singular_values[0], 4.0, epsilon = 1e-10); + assert_relative_eq!(result.singular_values[1], 3.0, epsilon = 1e-10); + } + + #[test] + fn test_left_absorb_reconstructs() { + let m = DMatrix::from_row_slice( + 2, + 3, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(2.0, 0.0), + Complex64::new(3.0, 0.0), + Complex64::new(4.0, 0.0), + Complex64::new(5.0, 0.0), + Complex64::new(6.0, 0.0), + ], + ); + let (u_s, vt) = truncated_svd_left_absorb(&m, 10, 1e-12, None).unwrap(); + let reconstructed = &u_s * &vt; + for i in 0..2 { + for j in 0..3 { + assert_relative_eq!(reconstructed[(i, j)].re, m[(i, j)].re, epsilon = 1e-10); + } + } + } + + #[test] + fn test_adaptive_truncation() { + // Build a matrix with known singular value spectrum: 10, 5, 1, 0.1, 0.01 + // Total weight = 100 + 25 + 1 + 0.01 + 0.0001 = 126.0201 + let mut m = DMatrix::zeros(5, 5); + let spectrum = [10.0_f64, 5.0, 1.0, 0.1, 0.01]; + for (i, &s) in spectrum.iter().enumerate() { + m[(i, i)] = Complex64::new(s, 0.0); + } + + // With max_rank=5, cutoff=0, no error budget: keep all 5 + let r1 = truncated_svd_with_error(&m, 5, 0.0, None).unwrap(); + assert_eq!(r1.singular_values.len(), 5); + + // With error budget 1e-4: total=126.02, discarding 0.01^2=0.0001 costs 0.0001/126.02 ~ 8e-7 + // Discarding 0.1^2 + 0.01^2 = 0.0101 costs 0.0101/126.02 ~ 8e-5 + // So error budget 1e-3 should drop the last two (keep 3) + let r2 = truncated_svd_with_error(&m, 5, 0.0, Some(1e-3)).unwrap(); + assert!( + r2.singular_values.len() <= 4, + "should drop small values, got {}", + r2.singular_values.len() + ); + assert!( + r2.singular_values.len() >= 2, + "should keep large values, got {}", + r2.singular_values.len() + ); + + // With tight error budget 1e-6: should keep almost all + let r3 = truncated_svd_with_error(&m, 5, 0.0, Some(1e-6)).unwrap(); + assert!(r3.singular_values.len() >= 4); + } + + #[test] + fn test_randomized_svd_low_rank() { + // Build a rank-2 matrix of size 20x20 (forces randomized path when max_rank=2) + // A = u * v^T where u is 20x2 and v is 20x2 + let u_col = DMatrix::from_fn(20, 2, |i, j| { + Complex64::new( + f64::from(u32::try_from(i * 3 + j * 7 + 1).unwrap()).sin(), + 0.0, + ) + }); + let v_col = DMatrix::from_fn(20, 2, |i, j| { + Complex64::new( + f64::from(u32::try_from(i * 5 + j * 11 + 3).unwrap()).cos(), + 0.0, + ) + }); + let a = &u_col * &v_col.adjoint(); + + // Randomized SVD with max_rank=2 should recover the matrix + let result = randomized_truncated_svd_with_error(&a, 2, 1e-12, None).unwrap(); + assert!(result.singular_values.len() <= 2); + + // Reconstruct and check + let mut u_s = result.u.clone(); + for (j, &sv) in result.singular_values.iter().enumerate() { + for i in 0..u_s.nrows() { + u_s[(i, j)] *= Complex64::new(sv, 0.0); + } + } + let reconstructed = &u_s * &result.vt; + let error = (&a - &reconstructed).norm(); + assert!( + error < 1e-6, + "reconstruction error {error} should be < 1e-6" + ); + } + + #[test] + fn test_randomized_svd_truncation() { + // Full-rank 20x20 matrix, truncate to rank 3 + let a = DMatrix::from_fn(20, 20, |i, j| { + Complex64::new( + f64::from(u32::try_from(i * 7 + j * 13 + 5).unwrap()).sin(), + f64::from(u32::try_from(i + j).unwrap()).cos(), + ) + }); + + let result_full = truncated_svd(&a, 3, 1e-15).unwrap(); + let result_rand = randomized_truncated_svd_with_error(&a, 3, 1e-15, None).unwrap(); + + // Both should return rank 3 + assert_eq!(result_full.singular_values.len(), 3); + assert_eq!(result_rand.singular_values.len(), 3); + + // Singular values should be close (randomized is approximate) + for (sf, sr) in result_full + .singular_values + .iter() + .zip(result_rand.singular_values.iter()) + { + assert_relative_eq!(sf, sr, epsilon = 0.1 * sf); + } + } + + #[test] + fn test_auto_selects_full_for_small() { + // Small matrix: should use full SVD (same result as truncated_svd) + let m = DMatrix::from_fn(4, 4, |i, j| { + Complex64::new(f64::from(u32::try_from(i + j).unwrap()), 0.0) + }); + let result_auto = truncated_svd_auto(&m, 2, 1e-12).unwrap(); + let result_full = truncated_svd(&m, 2, 1e-12).unwrap(); + assert_eq!( + result_auto.singular_values.len(), + result_full.singular_values.len() + ); + for (sa, sf) in result_auto + .singular_values + .iter() + .zip(result_full.singular_values.iter()) + { + assert_relative_eq!(sa, sf, epsilon = 1e-10); + } + } +} diff --git a/exp/pecos-stab-tn/src/mps/tensor.rs b/exp/pecos-stab-tn/src/mps/tensor.rs new file mode 100644 index 000000000..ee8db45c7 --- /dev/null +++ b/exp/pecos-stab-tn/src/mps/tensor.rs @@ -0,0 +1,193 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Tensor reshape and contraction utilities for MPS site tensors. +//! +//! Site tensors are stored as `DMatrix` with shape `(chi_l, d * chi_r)`. +//! The physical index `sigma in {0, ..., d-1}` selects a column block: +//! columns `[sigma * chi_r .. (sigma+1) * chi_r]`. + +use nalgebra::DMatrix; +use num_complex::Complex64; + +/// Extract the column block for physical index `sigma` from a site tensor. +/// +/// Site tensor has shape `(chi_l, d * chi_r)`. Returns a view of columns +/// `[sigma * chi_r .. (sigma+1) * chi_r]`, i.e. shape `(chi_l, chi_r)`. +#[must_use] +pub fn phys_block(tensor: &DMatrix, sigma: usize, chi_r: usize) -> DMatrix { + let start_col = sigma * chi_r; + tensor.columns(start_col, chi_r).clone_owned() +} + +/// Set the column block for physical index `sigma` in a site tensor. +pub fn set_phys_block( + tensor: &mut DMatrix, + sigma: usize, + chi_r: usize, + block: &DMatrix, +) { + let start_col = sigma * chi_r; + for j in 0..chi_r { + for i in 0..tensor.nrows() { + tensor[(i, start_col + j)] = block[(i, j)]; + } + } +} + +/// Reshape a site tensor from `(chi_l, d * chi_r)` to `(chi_l * d, chi_r)`. +/// +/// This puts the tensor in "left-grouped" form suitable for SVD when splitting +/// the bond to the right. +#[must_use] +pub fn reshape_left_group( + tensor: &DMatrix, + chi_l: usize, + d: usize, + chi_r: usize, +) -> DMatrix { + // Input: (chi_l, d * chi_r), stored as T[alpha_l, sigma * chi_r + alpha_r] + // Output: (chi_l * d, chi_r), stored as M[alpha_l * d + sigma, alpha_r] + let mut out = DMatrix::zeros(chi_l * d, chi_r); + for alpha_l in 0..chi_l { + for sigma in 0..d { + for alpha_r in 0..chi_r { + out[(alpha_l * d + sigma, alpha_r)] = tensor[(alpha_l, sigma * chi_r + alpha_r)]; + } + } + } + out +} + +/// Reshape from `(chi_l * d, chi_r)` back to `(chi_l, d * chi_r)`. +#[must_use] +pub fn reshape_left_ungroup( + matrix: &DMatrix, + chi_l: usize, + d: usize, + chi_r: usize, +) -> DMatrix { + let mut out = DMatrix::zeros(chi_l, d * chi_r); + for alpha_l in 0..chi_l { + for sigma in 0..d { + for alpha_r in 0..chi_r { + out[(alpha_l, sigma * chi_r + alpha_r)] = matrix[(alpha_l * d + sigma, alpha_r)]; + } + } + } + out +} + +/// Contract two adjacent site tensors into a combined two-site tensor. +/// +/// Left tensor: `(chi_l, d * chi_mid)`, right tensor: `(chi_mid, d * chi_r)`. +/// Result: `(chi_l, d * d * chi_r)` -- a "two-site" tensor with two physical indices. +/// +/// Layout of result: `T[alpha_l, sigma_l * d * chi_r + sigma_r * chi_r + alpha_r]` +#[must_use] +pub fn contract_two_sites( + left: &DMatrix, + chi_l: usize, + chi_mid: usize, + right: &DMatrix, + chi_r: usize, + d: usize, +) -> DMatrix { + let mut out = DMatrix::zeros(chi_l, d * d * chi_r); + for sigma_l in 0..d { + // left_block: (chi_l, chi_mid) for physical index sigma_l + let left_block = phys_block(left, sigma_l, chi_mid); + for sigma_r in 0..d { + // right_block: (chi_mid, chi_r) for physical index sigma_r + let right_block = phys_block(right, sigma_r, chi_r); + // contracted: (chi_l, chi_r) = left_block * right_block + let contracted = &left_block * &right_block; + // Place into output at combined physical index (sigma_l, sigma_r) + let out_col_start = (sigma_l * d + sigma_r) * chi_r; + for alpha_l in 0..chi_l { + for alpha_r in 0..chi_r { + out[(alpha_l, out_col_start + alpha_r)] = contracted[(alpha_l, alpha_r)]; + } + } + } + } + out +} + +/// Reshape a two-site tensor `(chi_l, d * d * chi_r)` into a matrix +/// `(chi_l * d, d * chi_r)` suitable for SVD splitting. +/// +/// Groups the left physical index with `chi_l` and right physical index with `chi_r`. +#[must_use] +pub fn reshape_two_site_for_svd( + tensor: &DMatrix, + chi_l: usize, + chi_r: usize, + d: usize, +) -> DMatrix { + let mut out = DMatrix::zeros(chi_l * d, d * chi_r); + for alpha_l in 0..chi_l { + for sigma_l in 0..d { + for sigma_r in 0..d { + for alpha_r in 0..chi_r { + let in_col = (sigma_l * d + sigma_r) * chi_r + alpha_r; + let out_row = alpha_l * d + sigma_l; + let out_col = sigma_r * chi_r + alpha_r; + out[(out_row, out_col)] = tensor[(alpha_l, in_col)]; + } + } + } + } + out +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_phys_block_roundtrip() { + // Create a 2x4 tensor (chi_l=2, d=2, chi_r=2) + let t = DMatrix::from_row_slice( + 2, + 4, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(2.0, 0.0), + Complex64::new(3.0, 0.0), + Complex64::new(4.0, 0.0), + Complex64::new(5.0, 0.0), + Complex64::new(6.0, 0.0), + Complex64::new(7.0, 0.0), + Complex64::new(8.0, 0.0), + ], + ); + let b0 = phys_block(&t, 0, 2); + let b1 = phys_block(&t, 1, 2); + assert_eq!(b0[(0, 0)], Complex64::new(1.0, 0.0)); + assert_eq!(b0[(0, 1)], Complex64::new(2.0, 0.0)); + assert_eq!(b1[(0, 0)], Complex64::new(3.0, 0.0)); + assert_eq!(b1[(1, 1)], Complex64::new(8.0, 0.0)); + } + + #[test] + fn test_reshape_roundtrip() { + let t = DMatrix::from_fn(3, 4, |i, j| { + Complex64::new(f64::from(u32::try_from(i * 4 + j).unwrap()), 0.0) + }); + let grouped = reshape_left_group(&t, 3, 2, 2); + assert_eq!(grouped.nrows(), 6); + assert_eq!(grouped.ncols(), 2); + let ungrouped = reshape_left_ungroup(&grouped, 3, 2, 2); + assert_eq!(ungrouped, t); + } +} diff --git a/exp/pecos-stab-tn/src/stab_mps.rs b/exp/pecos-stab-tn/src/stab_mps.rs new file mode 100644 index 000000000..e94dcaea9 --- /dev/null +++ b/exp/pecos-stab-tn/src/stab_mps.rs @@ -0,0 +1,6490 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! `StabMps` — hybrid stabilizer-tableau + MPS simulator. +//! +//! Represents a quantum state as: +//! +//! ```text +//! |psi> = sum_i nu_i D_i |phi> +//! ``` +//! +//! where |phi> is a stabilizer state tracked by a `SparseStabY` tableau, +//! `D_i` are destabilizer operators, and `nu_i` are complex coefficients +//! stored as an MPS. +//! +//! - Clifford gates: update only the tableau (O(n^2)), MPS untouched +//! - Non-Clifford gates (RZ): decompose `Z_q` in stabilizer basis, apply to MPS +//! +//! Based on: Masot-Llima, Garcia-Saez. "Stabilizer Tensor Networks: Universal +//! Quantum Simulator on a Basis of Stabilizer States." PRL 133, 230601 (2024). +//! arXiv:2403.08724. + +pub mod compile; +pub mod disentangle; +pub mod mast; +pub mod measure; +pub mod non_clifford; +pub mod ofd; +pub mod pauli_decomp; +pub mod renyi; +pub mod tableau_compose; + +use crate::mps::{Mps, MpsConfig}; +use nalgebra::DMatrix; +use num_complex::Complex64; +use pecos_core::{Angle64, QubitId}; +use pecos_random::PecosRng; +use pecos_simulators::{ + ArbitraryRotationGateable, CliffordGateable, MeasurementResult, QuantumSimulator, SparseStabY, +}; + +/// Known eigenstate at an MPS site, for exact disentangling. +/// Tracks which Pauli basis the site is a definite eigenstate of. +#[derive(Clone, Copy, Debug, PartialEq)] +pub enum SiteEigenstate { + /// |0⟩ or |1⟩ (Z eigenstate). Compatible with X or Y Pauli rotations. + Z(bool), + /// |+⟩ or |−⟩ (X eigenstate). Compatible with Z or Y Pauli rotations. + X(bool), + /// |+i⟩ or |−i⟩ (Y eigenstate). Compatible with X or Z Pauli rotations. + Y(bool), +} + +/// A gate applied in the MPS index space (for disentangling). +#[derive(Clone)] +pub(crate) struct MpsIndexGate { + site: usize, + inverse_matrix: DMatrix, +} + +/// Single-qubit Pauli kind for specifying multi-qubit Pauli strings +/// (e.g., stabilizer generators of QEC codes). +#[derive(Clone, Copy, Debug, PartialEq, Eq)] +pub enum PauliKind { + X, + Y, + Z, +} + +/// Single-qubit Clifford kind used internally for Pauli frame propagation. +#[derive(Clone, Copy, Debug, PartialEq, Eq)] +enum SingleQubitCliffordKind { + H, + SZ, + SZdg, + X, + Y, + Z, +} + +/// Runtime feature flags for `StabMps`, stored as a bitfield. +#[derive(Clone, Copy, Debug)] +pub struct StabMpsFlags(u8); + +impl StabMpsFlags { + const NORMALIZE_AFTER_GATE: u8 = 1 << 0; + const LAZY_MEASURE: u8 = 1 << 1; + const MERGE_RZ: u8 = 1 << 2; + const PAULI_FRAME_TRACKING: u8 = 1 << 3; + + /// Default flags: normalize enabled, everything else off. + #[must_use] + pub const fn new() -> Self { + Self(Self::NORMALIZE_AFTER_GATE) + } + + fn get(self, bit: u8) -> bool { + self.0 & bit != 0 + } + + fn set(&mut self, bit: u8, val: bool) { + if val { + self.0 |= bit; + } else { + self.0 &= !bit; + } + } + + #[must_use] + pub fn normalize_after_gate(self) -> bool { + self.get(Self::NORMALIZE_AFTER_GATE) + } + pub fn set_normalize_after_gate(&mut self, v: bool) { + self.set(Self::NORMALIZE_AFTER_GATE, v); + } + #[must_use] + pub fn lazy_measure(self) -> bool { + self.get(Self::LAZY_MEASURE) + } + pub fn set_lazy_measure(&mut self, v: bool) { + self.set(Self::LAZY_MEASURE, v); + } + #[must_use] + pub fn merge_rz(self) -> bool { + self.get(Self::MERGE_RZ) + } + pub fn set_merge_rz(&mut self, v: bool) { + self.set(Self::MERGE_RZ, v); + } + #[must_use] + pub fn pauli_frame_tracking(self) -> bool { + self.get(Self::PAULI_FRAME_TRACKING) + } + pub fn set_pauli_frame_tracking(&mut self, v: bool) { + self.set(Self::PAULI_FRAME_TRACKING, v); + } +} + +impl Default for StabMpsFlags { + fn default() -> Self { + Self::new() + } +} + +/// Builder for configuring an `StabMps` simulator. +pub struct StabMpsBuilder { + num_qubits: usize, + seed: Option, + max_bond_dim: usize, + svd_cutoff: f64, + max_truncation_error: Option, + parallel: bool, + auto_grow_bond_dim: Option, + auto_grow_max_bond_dim: usize, + flags: StabMpsFlags, +} + +impl StabMpsBuilder { + /// Maximum MPS bond dimension. Singular values beyond this are discarded + /// during SVD truncation after two-site gates. + /// + /// - Default: 64 + /// - Higher values give more accuracy at the cost of memory and time + /// - For n qubits, the exact max is 2^(n/2) + #[must_use] + pub fn max_bond_dim(mut self, dim: usize) -> Self { + self.max_bond_dim = dim; + self + } + + /// Minimum singular value to keep (absolute cutoff). + /// + /// - Default: 1e-12 + /// - Lower values keep more precision + #[must_use] + pub fn svd_cutoff(mut self, cutoff: f64) -> Self { + self.svd_cutoff = cutoff; + self + } + + /// Normalize the MPS after each non-Clifford gate. + /// Prevents unbounded norm drift from accumulated SVD numerical noise. + /// + /// - Default: true + /// - Set to false if you need to track the unnormalized state + #[must_use] + pub fn normalize_after_gate(mut self, normalize: bool) -> Self { + self.flags.set_normalize_after_gate(normalize); + self + } + + /// Set the RNG seed for reproducible measurements. + #[must_use] + pub fn seed(mut self, seed: u64) -> Self { + self.seed = Some(seed); + self + } + + /// Maximum relative truncation error per SVD (adaptive bond dimension). + /// + /// When set, bonds with low entanglement get small bond dimension (fast) + /// while bonds with high entanglement grow up to `max_bond_dim` (accurate). + /// The discarded weight at each SVD stays below this fraction. + /// + /// - Default: None (disabled, use fixed `max_bond_dim` only) + /// - Typical values: 1e-6 to 1e-3 + /// - `max_bond_dim` still acts as a hard cap + #[must_use] + pub fn max_truncation_error(mut self, error: f64) -> Self { + self.max_truncation_error = Some(error); + self + } + + /// Enable parallel MPS operations via rayon. + /// + /// - Default: false + /// - Useful for large bond dimensions (chi > 16) + /// - Do not enable when parallelizing at the shot/circuit level + #[must_use] + pub fn parallel(mut self, parallel: bool) -> Self { + self.parallel = parallel; + self + } + + /// Use lazy virtual-frame measurement: accumulate `pre_reduce` CNOTs AND + /// post-projection basis-rotation Cliffords into a deferred `V` queue + /// instead of applying them eagerly to the MPS. Pauli strings from + /// `decompose_z` are conjugated by `V†` before application to the + /// stored MPS, so expectation/projection are exact. + /// + /// - Default: false (eager path) + /// - **Not a universal win.** Per `examples/qec_bench.rs`, eager is + /// faster for both QEC-like (syndrome extraction + T noise) and + /// MAST-style (T-injection + ancilla measurement) workloads. Lazy + /// uses MPS addition for projection (bond grows ~2× per measurement) + /// whereas eager uses an in-place single-site basis-swap trick that + /// avoids bond growth. Lazy's only advantage is exact stored-MPS + /// state for subsequent non-measurement operations; eager's stored + /// MPS drifts slightly but measurement statistics and tableau stay + /// correct. Enable only if you need exact MPS state after random + /// measurements (e.g., computing `state_vector` or `amplitude` and + /// requiring no drift across many measurements). + #[must_use] + pub fn lazy_measure(mut self, lazy: bool) -> Self { + self.flags.set_lazy_measure(lazy); + self + } + + /// Enable adaptive bond-dim auto-grow. When the running truncation + /// error exceeds `threshold` AND the bond-dim cap was binding (a + /// truncation step actually discarded singular values at the cap), + /// the simulator doubles `max_bond_dim` (capped at + /// `auto_grow_max_bond_dim`, default 4096). + /// + /// Removes the manual tuning step for deep T-heavy circuits where + /// the default cap of 64 is insufficient. Cost: rebuild bond + /// allocation on growth (rare). Benefit: avoids surprise truncation + /// when entanglement spikes. + /// + /// - Default: `None` (disabled — fixed `max_bond_dim`). + /// - Typical thresholds: 1e-6 (conservative), 1e-4 (aggressive). + #[must_use] + pub fn auto_grow_bond_dim(mut self, threshold: f64) -> Self { + self.auto_grow_bond_dim = Some(threshold); + self + } + + /// Hard cap on `auto_grow_bond_dim`'s growth. Default: 4096. + #[must_use] + pub fn auto_grow_max_bond_dim(mut self, cap: usize) -> Self { + self.auto_grow_max_bond_dim = cap; + self + } + + /// Enable Pauli frame tracking: `inject_x_in_frame`, `inject_y_in_frame`, + /// `inject_z_in_frame`, and (when the flag is set) + /// `apply_depolarizing*` track Pauli errors as classical bits rather + /// than applying them to the quantum state. Clifford gates propagate + /// the frame via Heisenberg rules; measurements XOR the tracked + /// Z-bit into the outcome. + /// + /// **Big win** for Pauli-noise-heavy QEC simulation: each error is + /// a single bit flip (O(1)) instead of an O(n) tableau update. + /// + /// - Default: false. + /// - Sign tracking: `pauli_frame_phase` evolves through Clifford + /// propagation per Heisenberg sign-flip rules (H·Y·H = -Y, + /// SZ·Y·SZ† = -X, etc.) and folds into `global_phase` at flush. + /// - `State_vector` after flush: EXACT for all states. The frame is + /// applied to the MPS via `C† · P · C = phase · X_flip · Z_sign` + /// (decomposition in the MPS frame), not to the tableau. The + /// Clifford `C` is unchanged, the MPS absorbs the frame's full + /// content, and there is no state-dependent phase loss. + #[must_use] + pub fn pauli_frame_tracking(mut self, enable: bool) -> Self { + self.flags.set_pauli_frame_tracking(enable); + self + } + + /// Merge consecutive `rz(θ, q)` on the same qubit into a single + /// `rz(Σθ, q)` before invoking the non-Clifford path. Any gate + /// touching `q` (other than another `rz` on `q`) flushes the + /// accumulated angle first. Intended for ion-trap-style memory-error + /// models where every idle qubit receives a small RZ each time step: + /// adjacent idle rounds merge into one non-Clifford op. + /// + /// - Default: false. + /// - Semantics: strictly equivalent to applying each `rz` individually + /// (tableau and MPS paths both reduce non-Clifford count). No + /// accuracy trade-off. + /// - Clifford-angle RZ (0, π/2, π, 3π/2) is detected and applied + /// directly as before (no buffering). + #[must_use] + pub fn merge_rz(mut self, merge: bool) -> Self { + self.flags.set_merge_rz(merge); + self + } + + /// Preset for circuits with sparse T gates: Clifford-dominated QEC + /// circuits with occasional T gates or small-angle RZ, such as + /// magic-state distillation or T-gate injection. + /// + /// Enables aggressive MPS truncation that is safe when non-Clifford + /// content is sparse (t << N). NOT suitable for circuits with dense + /// coherent noise (e.g., RZ idle noise on every CX) where the MPS + /// grows more complex and truncation introduces bias. + /// + /// Sets: + /// - `max_truncation_error(1e-8)` — adaptive bond dim; bonds with low + /// entanglement shrink naturally, saving time on deep circuits. + /// - `max_bond_dim(128)` — 2x the library default, giving more headroom + /// for adversarial T-heavy subcircuits before truncation hits the cap. + /// - `merge_rz(true)` — fuses consecutive RZ on the same qubit. + /// + /// For dense non-Clifford noise (coherent idle RZ, many rotations), + /// use the default settings instead (no truncation threshold). + /// + /// Override any of these with subsequent builder calls: + /// ```ignore + /// StabMps::builder(n).for_sparse_t().max_bond_dim(64).build() + /// ``` + #[must_use] + pub fn for_sparse_t(self) -> Self { + self.for_sparse_t_with_bond_dim(128) + } + + /// Like `for_sparse_t()` but with a caller-chosen `max_bond_dim` cap. + #[must_use] + pub fn for_sparse_t_with_bond_dim(self, bond_dim: usize) -> Self { + self.max_truncation_error(1e-8) + .max_bond_dim(bond_dim) + .merge_rz(true) + } + + + /// Build the simulator. + #[must_use] + pub fn build(self) -> StabMps { + let config = MpsConfig { + max_bond_dim: self.max_bond_dim, + svd_cutoff: self.svd_cutoff, + max_truncation_error: self.max_truncation_error, + parallel: self.parallel, + }; + let (tableau, rng) = if let Some(seed) = self.seed { + ( + SparseStabY::with_seed(self.num_qubits, seed).with_destab_sign_tracking(), + PecosRng::seed_from_u64(seed), + ) + } else { + ( + SparseStabY::new(self.num_qubits).with_destab_sign_tracking(), + PecosRng::seed_from_u64(0), + ) + }; + StabMps { + num_qubits: self.num_qubits, + tableau, + mps: Mps::new(self.num_qubits, config.clone()), + config, + mps_corrections: Vec::new(), + global_phase: Complex64::new(1.0, 0.0), + disent_flags: vec![Some(SiteEigenstate::Z(false)); self.num_qubits], + gf2_matrix: ofd::Gf2FlipMatrix::new(self.num_qubits), + rng, + stats: StabMpsStats::default(), + deferred_ops: Vec::new(), + pragmatic_drift_count: 0, + pending_rz: vec![None; self.num_qubits], + auto_grow_bond_dim: self.auto_grow_bond_dim, + auto_grow_max_bond_dim: self.auto_grow_max_bond_dim, + last_truncation_error: 0.0, + pauli_frame_x: vec![false; self.num_qubits], + pauli_frame_z: vec![false; self.num_qubits], + pauli_frame_phase: Complex64::new(1.0, 0.0), + flags: self.flags, + } + } +} + +/// Stabilizer Tensor Network simulator. +#[derive(Clone)] +pub struct StabMps { + num_qubits: usize, + tableau: SparseStabY, + mps: Mps, + config: MpsConfig, + /// Inverse of disentangling gates applied to MPS (in index space). + mps_corrections: Vec, + /// Global phase accumulated from Clifford-angle RZ gates. + global_phase: Complex64, + /// Per-site eigenstate tracking for exact disentangling. + disent_flags: Vec>, + /// GF(2) flip matrix for OFD diagnostic. + gf2_matrix: ofd::Gf2FlipMatrix, + rng: PecosRng, + /// Diagnostic counters. Updated by `non_clifford::apply_rz_stab_mps`. + pub stats: StabMpsStats, + /// Deferred virtual-frame Clifford V (see `measure::DeferredOp`). + deferred_ops: Vec, + /// Count of pragmatic-path measurement drifts. + pragmatic_drift_count: u64, + /// Pending non-Clifford RZ angle per qubit when `merge_rz` is on. + pending_rz: Vec>, + /// Auto-grow bond-dim threshold; `None` disables. + auto_grow_bond_dim: Option, + /// Hard cap when auto-growing. + auto_grow_max_bond_dim: usize, + /// Snapshot of `mps.truncation_error()` at the last auto-grow check. + last_truncation_error: f64, + /// Pauli frame X bit per qubit. + pauli_frame_x: Vec, + /// Pauli frame Z bit per qubit. + pauli_frame_z: Vec, + /// Global scalar of the Pauli frame. + pauli_frame_phase: Complex64, + /// Runtime feature flags. + flags: StabMpsFlags, +} + +/// Runtime statistics for diagnostics. +#[derive(Clone, Copy, Debug, Default)] +pub struct StabMpsStats { + /// Total non-Clifford RZ calls (Clifford-angle RZs not counted). + pub total_nonclifford: u64, + /// Non-Cliffords that hit the single-site decomposition (cheap). + pub single_site: u64, + /// Non-Cliffords that fired multi-site disent (tableau right-compose). + pub multi_disent: u64, + /// Non-Cliffords that fell through to the std multi-site CNOT cascade path. + pub multi_std: u64, + /// Non-Cliffords that hit the Stabilizer branch (scalar or diagonal). + pub stabilizer: u64, + /// OFD diagnostic: non-Cliffords whose flip pattern is in the span of + /// previously-added patterns (would not increase bond dim under OFD). + pub ofd_in_span: u64, + /// OFD diagnostic: non-Cliffords whose flip pattern is linearly independent + /// from previous (OFD would grow bond dim by factor 2). + pub ofd_new_dim: u64, + /// Cross-tab: OFD `in_span` gates that the heuristic routed through std path. + /// These are the "OFD wins" — OFD would avoid MPS CNOT cascade. + pub ofd_in_span_std: u64, + /// Cross-tab: OFD `in_span` gates that the heuristic routed through single-site. + /// Both paths are cheap; OFD doesn't improve here. + pub ofd_in_span_single: u64, + /// Cross-tab: OFD `in_span` gates that the heuristic routed through disent path. + pub ofd_in_span_disent: u64, +} + +impl StabMps { + /// Create a builder for configuring the simulator. + #[must_use] + pub fn builder(num_qubits: usize) -> StabMpsBuilder { + StabMpsBuilder { + num_qubits, + seed: None, + max_bond_dim: 64, + svd_cutoff: 1e-12, + max_truncation_error: None, + parallel: false, + auto_grow_bond_dim: None, + auto_grow_max_bond_dim: 4096, + flags: StabMpsFlags::new(), + } + } + + /// Create a new STN simulator with default configuration. + #[must_use] + pub fn new(num_qubits: usize) -> Self { + Self::builder(num_qubits).build() + } + + /// Create with a specific seed for reproducibility. + #[must_use] + pub fn with_seed(num_qubits: usize, seed: u64) -> Self { + Self::builder(num_qubits).seed(seed).build() + } + + #[must_use] + pub fn num_qubits(&self) -> usize { + self.num_qubits + } + + /// Current maximum bond dimension in the MPS. + #[must_use] + pub fn max_bond_dim(&self) -> usize { + self.mps.max_bond_dim() + } + + /// Theoretical minimum bond dimension from GF(2) OFD analysis. + /// + /// Returns `2^(t - rank)` where t is the number of non-Clifford gates + /// applied and rank is the GF(2) rank of the flip pattern matrix. + /// This is the best bond dimension achievable by Clifford disentangling. + #[must_use] + pub fn theoretical_min_bond_dim(&self) -> usize { + self.gf2_matrix.theoretical_min_bond_dim() + } + + /// OFD null space dimension (Liu-Clark 2412.17209 Section III.C). + /// + /// Returns `t - rank` where t is the number of absorbed non-Clifford gates + /// and rank is the GF(2) rank of their flip patterns. This is the number + /// of gates that could NOT be disentangled (required bond-dim growth). + /// + /// The bond dimension lower bound from OFD is `2^nullity`. + /// + /// For research circuits where nullity < log₂(N), the simulation is + /// efficient (polynomial in N). + #[must_use] + pub fn ofd_nullity(&self) -> usize { + let t = self.gf2_matrix.num_gates(); + let r = self.gf2_matrix.gf2_rank(); + t.saturating_sub(r) + } + + /// Number of non-Clifford gates that OFD disentangled (rank of GF(2) matrix). + #[must_use] + pub fn ofd_disentangled_count(&self) -> usize { + self.gf2_matrix.gf2_rank() + } + + /// Total non-Clifford gates recorded in the GF(2) basis. + #[must_use] + pub fn ofd_total_absorbed(&self) -> usize { + self.gf2_matrix.num_gates() + } + + /// Access the GF(2) flip matrix (for diagnostics). + #[must_use] + pub fn gf2_matrix(&self) -> &ofd::Gf2FlipMatrix { + &self.gf2_matrix + } + + /// Wavefunction amplitude ⟨s|C|ψ⟩ for a given bitstring `s`. + /// + /// `bitstring` has length `num_qubits`; bit k corresponds to qubit k. + /// Returns the unnormalized amplitude coefficient. + /// + /// For n ≤ 14 uses `state_vector()` directly. Paper Liu-Clark 2412.17209 + /// Section VI.B gives an iterative CAMPS-native algorithm for larger n. + /// + /// # Panics + /// Panics if bitstring length doesn't match `num_qubits`, or n > 14. + #[must_use] + pub fn amplitude(&self, bitstring: &[bool]) -> Complex64 { + assert_eq!( + bitstring.len(), + self.num_qubits, + "bitstring length mismatch" + ); + assert!(self.num_qubits <= 14, "amplitude requires n <= 14"); + let sv = self.state_vector(); + // Convert bitstring to index per state_vector convention: + // x = Σ_k σ_k * 2^{n-1-k} where σ_0 is MSB. + let mut idx = 0usize; + for (k, &b) in bitstring.iter().enumerate() { + if b { + idx |= 1 << (self.num_qubits - 1 - k); + } + } + sv[idx] + } + + /// Compute `⟨Ψ|P|Ψ⟩` for an arbitrary multi-qubit Pauli string `P`. + /// + /// `pauli_string` lists non-identity factors as `(qubit, PauliKind)` + /// pairs; qubits not listed get `I`. Returns the real expectation + /// value (the Hermitian Pauli always has real expectation). + /// + /// Building block for code-state fidelity at large `n` (sum over + /// stabilizer group of `⟨Ψ|g|Ψ⟩`), variational energy estimation, + /// and arbitrary-observable readout. + /// + /// # Method + /// Tableau-based decomposition: writes `P` as + /// `phase · X_{flip} · Z_{sign}` (in stored-MPS frame, after + /// conjugating by `C†`) + /// using `pauli_decomp::decompose_pauli_string`, then evaluates via + /// `measure::pauli_expectation` on the MPS. Scales to arbitrary `n`. + /// + /// # Panics + /// Panics if any qubit index exceeds `num_qubits`. + #[must_use] + pub fn pauli_expectation(&self, pauli_string: &[(usize, PauliKind)]) -> f64 { + // Translate public PauliKind into pauli_decomp's enum. + let decomp_input: Vec<(usize, pauli_decomp::PauliKindForDecomp)> = pauli_string + .iter() + .map(|&(q, k)| { + assert!(q < self.num_qubits, "pauli qubit index {q} >= num_qubits"); + let pk = match k { + PauliKind::X => pauli_decomp::PauliKindForDecomp::X, + PauliKind::Y => pauli_decomp::PauliKindForDecomp::Y, + PauliKind::Z => pauli_decomp::PauliKindForDecomp::Z, + }; + (q, pk) + }) + .collect(); + let (flip, sign, phase) = pauli_decomp::decompose_pauli_string( + self.tableau.stabs(), + self.tableau.destabs(), + &decomp_input, + ); + measure::pauli_expectation(&self.mps, &flip, &sign, phase).re + } + + /// Compute the overlap `⟨s|Ψ⟩` where `|s⟩` is a stabilizer state given + /// as a CH-form simulator. Uses the importance-sampling estimator from + /// CD-Loschmidt-echoes (Mello, Santini, Collura, arXiv:2502.01872 Eq. 1): + /// + /// `⟨s|Ψ⟩ = E_{x ~ |⟨x|s⟩|²}[ ⟨x|Ψ⟩ / ⟨x|s⟩ ]` + /// + /// Variance is `1 − |⟨s|Ψ⟩|²` (independent of N — Eq. 2 of the paper), + /// so a few hundred samples typically suffice for 1% statistical error. + /// Scales to arbitrary `n` (uses `amplitude_iterative` for `⟨x|Ψ⟩` and + /// CH-form `amplitude` + sequential measurement for `⟨x|s⟩` and + /// stabilizer Born sampling). + /// + /// Note: requires `n ≤ 64` due to CH-form's `usize`-indexed amplitude + /// API; that's already a much higher limit than the SV path's `n ≤ 14`. + /// + /// # Arguments + /// - `s`: CH-form simulator representing the stabilizer state `|s⟩`. + /// Caller is responsible for setting up the desired Clifford circuit + /// on `s` before passing it in. **Mutated** as samples are drawn + /// (cloned internally per sample); a fresh CH-form is used per shot. + /// - `num_samples`: number of MC samples. ~100 gives ~10% error, + /// ~10000 gives ~1% error. + /// - `rng_seed`: optional seed for per-sample CH-form clones. When + /// `None`, uses a deterministic hash of the sample index (reproducible + /// but not caller-controllable). Pass `Some(seed)` to control the + /// MC stream for reproducibility across runs. + /// + /// # Returns + /// Complex MC estimate of `⟨s|Ψ⟩`. Take `.norm_sqr()` for a fidelity + /// estimate `|⟨s|Ψ⟩|²`. + /// + /// # Limitations + /// - Requires `n <= 64` (usize bitstring index in CH-form). + /// - Statistical estimator: not exact. Use `code_state_fidelity` for + /// exact answer at `n <= 14`. + /// - The CH-form `s` must be on the same number of qubits as `self`. + /// + /// # Panics + /// + /// Panics if `s.num_qubits() != self.num_qubits` or `num_qubits > 64`. + #[must_use] + pub fn overlap_with_stabilizer< + R: pecos_random::SeedableRng + pecos_random::Rng + std::fmt::Debug + Clone, + >( + &self, + s: &pecos_simulators::CHForm, + num_samples: usize, + rng_seed: Option, + ) -> Complex64 { + use pecos_core::RngManageable; + + assert_eq!( + s.num_qubits(), + self.num_qubits, + "stabilizer-state qubit count mismatch" + ); + assert!( + self.num_qubits <= 64, + "overlap_with_stabilizer requires n <= 64" + ); + + let n = self.num_qubits; + let mut acc = Complex64::new(0.0, 0.0); + let mut samples_used = 0usize; + + for sample_idx in 0..num_samples { + // Per-sample clone of |s⟩ with a fresh RNG seed so each sample + // produces an independent bitstring from the Born distribution. + // Use sample_idx-based seed (self is &self so we can't advance + // self.rng). The wrapping_mul mixes bits to avoid trivial overlap. + let mut s_sampler = s.clone(); + let base_seed = rng_seed.unwrap_or(42); + let sample_seed = (sample_idx as u64) + .wrapping_mul(2_654_435_761) + .wrapping_add(base_seed); + s_sampler.set_rng(R::seed_from_u64(sample_seed)); + let mut bitstring = vec![false; n]; + for (q, bit) in bitstring.iter_mut().enumerate() { + let outcome = s_sampler.mz(&[pecos_core::QubitId(q)])[0].outcome; + *bit = outcome; + } + // Compute x as usize index per CH-form's amplitude API: + // bit q of x corresponds to qubit q's outcome (LSB-first). + let mut x_idx = 0usize; + for (q, &bit) in bitstring.iter().enumerate() { + if bit { + x_idx |= 1usize << q; + } + } + let amp_xs = s.amplitude(x_idx); + if amp_xs.norm_sqr() < 1e-30 { + // Zero-amplitude sample: should be impossible if we sampled + // from the correct Born distribution. Skip defensively. + continue; + } + // Compute via amplitude_iterative. + // Convert bitstring to amplitude_iterative's convention: + // amplitude(bs) treats bs[k] as qubit (n-1-k), so we reverse. + let bs_rev: Vec = bitstring.iter().rev().copied().collect(); + let amp_xpsi = self.amplitude_iterative(&bs_rev); + acc += amp_xpsi / amp_xs; + samples_used += 1; + } + if samples_used == 0 { + eprintln!( + "warning: overlap_with_stabilizer: all {num_samples} samples had zero amplitude — returning 0" + ); + return Complex64::new(0.0, 0.0); + } + acc / Complex64::new( + f64::from(u32::try_from(samples_used).expect("samples fit in u32")), + 0.0, + ) + } + + /// Compute `⟨Ψ|P_code|Ψ⟩` where `P_code` is the projector onto the + /// stabilizer code subspace defined by `stabilizer_generators`. + /// + /// Each generator is a Pauli string given as a `Vec<(usize, PauliKind)>` + /// listing non-identity factors. `P_code = Π_i (I + g_i)/2` for `k` + /// generators yields a fidelity in [0, 1]: 1 means `|Ψ⟩` is fully + /// inside the code subspace, 0 means fully outside. + /// + /// Useful for QEC verification: after running a code's preparation / + /// syndrome-extraction circuit, this returns how much of the state is + /// in the codespace. Compare against expected value (1.0 for noiseless, + /// less for noisy circuits). + /// + /// # Method + /// Expands `P_code = (1/2^k) Σ_{g ∈ stabilizer group} g` and computes + /// `(1/2^k) Σ ⟨Ψ|g|Ψ⟩` via `pauli_expectation` per group element. + /// Scales to arbitrary `n` (the bottleneck is `2^k` group enumeration + /// where `k = stabilizer_generators.len()`). + /// + /// For codes with many generators, prefer + /// `StabMps::overlap_with_stabilizer` (CD Loschmidt MC) targeting one + /// specific code state at a time. + /// + /// # Panics + /// Panics if any qubit index in a generator is ≥ `num_qubits`, or if + /// `2^k` overflows `usize` (e.g., k > 62 on 64-bit). + #[must_use] + pub fn code_state_fidelity(&self, stabilizer_generators: &[Vec<(usize, PauliKind)>]) -> f64 { + let k = stabilizer_generators.len(); + assert!( + k <= 30, + "code_state_fidelity: 2^k group enumeration with k={k} would take too long" + ); + let n = self.num_qubits; + for gen_string in stabilizer_generators { + for &(q, _) in gen_string { + assert!(q < n, "generator qubit index {q} >= num_qubits {n}"); + } + } + let group_size = 1usize << k; + let mut acc = 0.0; + for mask in 0..group_size { + // Compose group element by multiplying generators selected by mask. + // Use Pauli aggregation via decompose_pauli_string's per-qubit logic + // — but we just need <Ψ|g|Ψ>, so flatten the selected generators + // into one Pauli-string list and let pauli_expectation aggregate. + let mut composed: Vec<(usize, PauliKind)> = Vec::new(); + for (i, generator) in stabilizer_generators.iter().enumerate() { + if (mask >> i) & 1 == 1 { + composed.extend_from_slice(generator); + } + } + acc += self.pauli_expectation(&composed); + } + acc / f64::from(u32::try_from(group_size).expect("group_size fits in u32")) + } + + /// Complex amplitude ⟨s|Ψ⟩ via iterative forced projection without + /// renormalization (Liu-Clark 2412.17209 Section VI.B). + /// + /// Scales beyond `amplitude`'s n ≤ 14 limit by working directly on the + /// MPS + tableau. After forcing all N outcomes, the tableau encodes |s⟩ + /// as a computational basis state and the MPS (left unnormalized) + /// contains the amplitude at its |0^N⟩ coefficient: + /// amp(s) = `global_phase` · `ν_final(0^N)`. + /// + /// # Correctness + /// Exact match to `amplitude` (SV-based) at n ≤ 14 for Clifford+T + /// circuits. Scales to arbitrary n via MPS operations. Probabilities + /// via `prob_bitstring` are always correct. + /// + /// # Panics + /// Panics if bitstring length doesn't match `num_qubits`. + #[must_use] + pub fn amplitude_iterative(&self, bitstring: &[bool]) -> Complex64 { + assert_eq!( + bitstring.len(), + self.num_qubits, + "bitstring length mismatch" + ); + let mut tab = self.tableau.clone(); + let mut mps = self.mps.clone(); + let n = self.num_qubits; + // Convention: `amplitude(bs)` treats `bs[k]` as qubit (n-1-k), so + // project qubit q with bitstring[n-1-q]. + for q in 0..n { + let s_q = bitstring[n - 1 - q]; + if !measure::project_forced_z_unnormalized(&mut tab, &mut mps, q, s_q) { + return Complex64::new(0.0, 0.0); + } + } + let zero: Vec = vec![0u8; n]; + self.global_phase * mps.amplitude(&zero) + } + + /// Probability of measuring `bitstring` in the computational basis. + /// + /// Implements Liu-Clark 2412.17209 Algorithm 3 (Section VI.A): iterative + /// forced projection of the CAMPS state. For each qubit k: + /// `π_k` = ⟨`ψ_k` | (I + (-`1)^{s_k`} `Z̃_k)/2` | `ψ_k`⟩ + /// |ψ_{k+1}⟩ ∝ (I + (-`1)^{s_k`} `Z̃_k)/2` |`ψ_k`⟩ + /// where `Z̃_k` is the tableau's Z-mapping on qubit k. Final probability is + /// the product of conditional probabilities `π_k`. + /// + /// Scales beyond n = 14 (unlike `amplitude`) by working directly on the + /// MPS + tableau instead of the full state vector. + /// + /// # Panics + /// Panics if bitstring length doesn't match `num_qubits`. + #[must_use] + pub fn prob_bitstring(&self, bitstring: &[bool]) -> f64 { + assert_eq!( + bitstring.len(), + self.num_qubits, + "bitstring length mismatch" + ); + let mut tab = self.tableau.clone(); + let mut mps = self.mps.clone(); + let n = self.num_qubits; + let mut total_prob: f64 = 1.0; + // Convention: bitstring[k] is qubit (n-1-k) (matches `amplitude`). + for q in 0..n { + let s_q = bitstring[n - 1 - q]; + let pi_q = measure::project_forced_z(&mut tab, &mut mps, q, s_q); + total_prob *= pi_q; + if total_prob < 1e-30 { + return 0.0; + } + } + total_prob.clamp(0.0, 1.0) + } + + /// Second Rényi entropy `S_2` = -`ln(Tr_A(ρ_A²))` at a bipartition + /// (qubits 0..cut vs qubits cut..N). + /// + /// Uses the full `state_vector` for computation — works only for n <= 14. + /// Paper Liu-Clark 2412.17209 Section VI.C gives an MPS-based algorithm + /// that scales better but requires careful implementation of the Pauli + /// generator enumeration and CAMPS-specific Gaussian elimination. + /// + /// # Panics + /// Panics if cut == 0 or cut >= `num_qubits`, or if `num_qubits` > 14. + #[must_use] + pub fn renyi_s2(&self, cut: usize) -> f64 { + let n = self.num_qubits; + assert!(cut > 0 && cut < n, "cut must be in (0, num_qubits)"); + assert!( + n <= 14, + "renyi_s2 requires n <= 14 (uses full state vector)" + ); + + let sv = self.state_vector(); + let dim_a = 1usize << cut; + let dim_b = 1usize << (n - cut); + // state_vector is LSB-first: `sv[idx]` has qubit k at bit k of idx. + // Convention: A = first `cut` qubits (0..cut) → low bits. + // B = qubits cut..n → high bits. + // idx = a_bits | (b_bits << cut) + // + // Reduced density ρ_A: (ρ_A)_{a, a'} = Σ_b ψ(a, b) · ψ*(a', b) + let mut rho_a = vec![Complex64::new(0.0, 0.0); dim_a * dim_a]; + for a in 0..dim_a { + for a_prime in 0..dim_a { + let mut acc = Complex64::new(0.0, 0.0); + for b in 0..dim_b { + let idx1 = a | (b << cut); + let idx2 = a_prime | (b << cut); + acc += sv[idx1] * sv[idx2].conj(); + } + rho_a[a * dim_a + a_prime] = acc; + } + } + + // S_2 = -ln(Tr(ρ_A^2)) = -ln(Σ_{a,a'} |ρ_A[a, a']|^2). + let mut tr_sq = 0.0_f64; + for a in 0..dim_a { + for a_prime in 0..dim_a { + tr_sq += rho_a[a * dim_a + a_prime].norm_sqr(); + } + } + if tr_sq < 1e-30 { + f64::INFINITY + } else { + -tr_sq.ln() + } + } + + /// CAMPS-native `S_2` entropy via Pauli Coefficient Enumeration (Liu-Clark + /// Section VI.C). Does NOT require constructing the state vector, so scales + /// beyond n = 14 when the MPS has bond dim 1 and T-gate density is moderate. + /// + /// `cut` places qubits [0, cut) in region A, [cut, n) in region B. + /// + /// Complexity: ∏_j (1 + `non_zero_bloch_components(j)`) combinations. For + /// Clifford+T with sparse T gates most sites give count=1 → 2^N fallback. + /// Full-magic sites give count=3 -> 4^N worst case. Error if > 2^22. + /// + /// # Errors + /// + /// Returns an error string if the cut is out of range or the number of + /// Pauli combinations exceeds the safety limit. + pub fn s2_pce(&self, cut: usize) -> Result { + let n = self.num_qubits; + if cut == 0 || cut >= n { + return Err(format!("cut {cut} must be in (0, {n})")); + } + let mask: Vec = (0..n).map(|q| q < cut).collect(); + renyi::compute_s2_pce(&self.mps, &self.tableau, &mask) + } + + /// Fast `S_2` via GF(2) null-space enumeration (PCMPS). Requires every MPS + /// site to have a single Pauli-axis Bloch vector (typical for STN + /// Clifford+T where T gets absorbed into the tableau). Falls back to + /// [`StabMps::s2_pce`] if multi-axis sites are present. + /// + /// Scales to much larger n than PCE when applicable: `2^null_dim` + /// enumerations vs 2^N. For pure-Clifford Bell on n=100, `null_dim` is + /// typically 0-2. + /// + /// # Errors + /// + /// Returns an error string if the cut is out of range, or if the null-space + /// enumeration is too large. + pub fn s2_pcmps(&self, cut: usize) -> Result { + let n = self.num_qubits; + if cut == 0 || cut >= n { + return Err(format!("cut {cut} must be in (0, {n})")); + } + let mask: Vec = (0..n).map(|q| q < cut).collect(); + // Fast path: single-axis-per-site PCMPS (Clifford-state analytic + // short-circuit handles pure Clifford at any n). + if let Ok(s) = renyi::compute_s2_pcmps(&self.mps, &self.tableau, &mask) { + return Ok(s); + } + // General path: 2N-bit F_2 null-space TN enumeration. Handles + // multi-axis Bloch but null_dim capped at 22. + if let Ok(s) = renyi::compute_s2_pcmps_tn(&self.mps, &self.tableau, &mask) { + return Ok(s); + } + // Last resort: full PCE (4^N hard cap). + renyi::compute_s2_pce(&self.mps, &self.tableau, &mask) + } + + /// Access the MPS (for testing). + #[must_use] + pub fn mps(&self) -> &Mps { + &self.mps + } + + /// Accumulated truncation error so far (approximate `1 - |⟨ψ_exact|ψ⟩|²`). + /// Zero if no SVD has dropped any singular values above `svd_cutoff`. + #[must_use] + pub fn truncation_error(&self) -> f64 { + self.mps.truncation_error() + } + + /// Number of SVDs where `max_bond_dim` was the binding cap. If > 0 the + /// state is under-resolved; consider raising `max_bond_dim` or loosening + /// `max_truncation_error`. + #[must_use] + pub fn bond_cap_hits(&self) -> u64 { + self.mps.bond_cap_hits() + } + + /// Access the tableau (for testing). + #[must_use] + pub fn tableau(&self) -> &SparseStabY { + &self.tableau + } + + /// Run Clifford disentangling sweeps to reduce MPS bond dimension. + /// + /// Tries two-qubit Clifford gates at each bond. If one reduces entanglement, + /// it's applied to the MPS and the inverse to the tableau. + /// Returns the number of gates applied. + pub fn disentangle(&mut self, max_sweeps: usize) -> usize { + disentangle::disentangle(&mut self.mps, &mut self.mps_corrections, max_sweeps) + } + + /// Compute the full state vector (for testing on small systems). + /// + /// Directly computes |psi> = `Σ_x` `ν_x` * D^x * |stab> from the MPS + /// coefficients and the current stabilizer/destabilizer generators. + /// + /// # Accuracy caveats (read if you have outstanding measurements) + /// + /// - **Default (pragmatic-fix) measurement path**: `measure_qubit_stab_mps` + /// skips MPS compensation for `pre_reduce` row-ops. The stored + /// `(tableau, MPS)` pair may no longer represent the exact physical + /// state after a measurement that triggered multi-anticom + /// `pre_reduce`. Measurement outcome statistics stay correct, but + /// `state_vector`/`amplitude` reads can drift. If exact state is + /// needed, use `StabMpsBuilder::lazy_measure(true)`. + /// - **Merged-RZ pending buffer** (`merge_rz = true`): any pending + /// merged-RZ angle has not been applied yet. Call `StabMps::flush()` + /// first. + /// - **Pauli-frame tracking** (`pauli_frame_tracking = true`): the + /// frame's Pauli bits are not in the returned state vector. Call + /// `StabMps::flush_pauli_frame_to_state()` first for frame-applied + /// output (modulo a global phase for Y contributions). + /// + /// # Panics + /// + /// Panics if `num_qubits > 14`. + #[must_use] + pub fn state_vector(&self) -> Vec { + assert!( + self.num_qubits <= 14, + "state_vector only for small systems (N <= 14)" + ); + + let n = self.num_qubits; + let dim = 1usize << n; + let mut mps_sv = self.mps.state_vector(); + + // Undo disentangling corrections (reverse order) so MPS SV matches the tableau. + // MPS uses MSB-first: bit (n-1-k) = destabilizer index k. + for correction in self.mps_corrections.iter().rev() { + let k = correction.site; + let bit_hi = n - 1 - k; + let bit_lo = n - 1 - (k + 1); + let mat = &correction.inverse_matrix; + let mut new_sv = vec![Complex64::new(0.0, 0.0); dim]; + for (idx, &sv_val) in mps_sv.iter().enumerate() { + let sigma_in = ((idx >> bit_hi) & 1) * 2 + ((idx >> bit_lo) & 1); + let base = idx & !(1 << bit_hi) & !(1 << bit_lo); + for sigma_out in 0..4usize { + let out_idx = base | ((sigma_out >> 1) << bit_hi) | ((sigma_out & 1) << bit_lo); + new_sv[out_idx] += mat[(sigma_out, sigma_in)] * sv_val; + } + } + mps_sv = new_sv; + } + + // Build Pauli matrices for generator construction. + let i2 = DMatrix::::identity(2, 2); + let x_mat = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let z_mat = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(-1.0, 0.0), + ], + ); + let y_mat = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(0.0, -1.0), + Complex64::new(0.0, 1.0), + Complex64::new(0.0, 0.0), + ], + ); + + // Helper: build the 2^n × 2^n matrix for a generator row. + let gen_matrix = |is_stab: bool, row: usize| -> DMatrix { + let gens = if is_stab { + self.tableau.stabs() + } else { + self.tableau.destabs() + }; + let mut result = DMatrix::from_element(1, 1, Complex64::new(1.0, 0.0)); + for q in 0..n { + let p = match (gens.row_x[row].contains(q), gens.row_z[row].contains(q)) { + (false, false) => &i2, + (true, false) => &x_mat, + (false, true) => &z_mat, + (true, true) => &y_mat, + }; + result = result.kronecker(p); + } + let mut phase = Complex64::new(1.0, 0.0); + if gens.signs_minus.contains(row) { + phase *= Complex64::new(-1.0, 0.0); + } + if gens.signs_i.contains(row) { + phase *= Complex64::new(0.0, 1.0); + } + result * phase + }; + + // Find stabilizer state |stab>: +1 eigenstate of all stabilizers. + // Build the projector P = prod_k (I + S_k) / 2, then find a nonzero + // column to get the stabilizer state. + let id = DMatrix::::identity(dim, dim); + let mut proj = id.clone(); + for k in 0..n { + let sk = gen_matrix(true, k); + proj = (&id + &sk) * Complex64::new(0.5, 0.0) * &proj; + } + // Find a nonzero column of the projector + let mut stab_state = nalgebra::DVector::from_element(dim, Complex64::new(0.0, 0.0)); + for col in 0..dim { + let candidate = proj.column(col); + let norm_sq: f64 = candidate.iter().map(nalgebra::Complex::norm_sqr).sum(); + if norm_sq > 1e-20 { + stab_state = candidate.into_owned() / Complex64::new(norm_sq.sqrt(), 0.0); + break; + } + } + + // Compute |psi> = Σ_x ν_x * D_0^{x_0} * ... * D_{n-1}^{x_{n-1}} * |stab>. + // MPS SV uses MSB-first: index x = Σ_k σ_k * 2^{n-1-k}. + let mut psi = nalgebra::DVector::from_element(dim, Complex64::new(0.0, 0.0)); + for (x, &nu) in mps_sv.iter().enumerate() { + if nu.norm_sqr() < 1e-30 { + continue; + } + let mut state = stab_state.clone(); + for k in 0..n { + if (x >> (n - 1 - k)) & 1 == 1 { + state = &gen_matrix(false, k) * &state; + } + } + psi += state * nu; + } + + // Convert from Kronecker ordering (MSB-first: q0 is leftmost) + // to DenseStateVec ordering (LSB-first: bit k = qubit k). + let mut result = vec![Complex64::new(0.0, 0.0); dim]; + for i in 0..dim { + let mut rev = 0; + for b in 0..n { + if (i >> b) & 1 == 1 { + rev |= 1 << (n - 1 - b); + } + } + result[rev] = self.global_phase * psi[i]; + } + + // Normalize (MPS norm can drift from truncation in multi-site gates) + let norm_sq: f64 = result.iter().map(nalgebra::Complex::norm_sqr).sum(); + if norm_sq > 1e-20 { + let inv_norm = Complex64::new(1.0 / norm_sq.sqrt(), 0.0); + for a in &mut result { + *a *= inv_norm; + } + } + + result + } +} + +impl StabMps { + /// Sample `num_shots` bitstrings from the Born distribution + /// `|⟨x|Ψ⟩|²` of the current state. Each shot clones the simulator, + /// measures all qubits in the Z basis (consuming the clone), and + /// returns the bitstring. The original simulator state is unchanged + /// (only the internal RNG advances, to ensure each shot uses a + /// distinct RNG seed). + /// + /// `bitstring[k]` corresponds to qubit `k`'s outcome. + /// + /// Useful for shot-based experiments (logical error rate estimation, + /// outcome distribution histograms, etc.). + pub fn sample_bitstring(&mut self, num_shots: usize) -> Vec> { + use pecos_core::RngManageable; + let mut shots = Vec::with_capacity(num_shots); + for _shot in 0..num_shots { + let shot_seed = self.rng.next_u64(); + let mut clone = self.clone(); + // Re-seed both the StabMps-level RNG (used by random measurement + // probability sampling) and the tableau's internal RNG (used + // by the trivial-MPS measurement fast path). Otherwise clones + // would all share the parent's RNG state and produce identical + // outcomes. + clone.rng = PecosRng::seed_from_u64(shot_seed); + clone + .tableau + .set_rng(PecosRng::seed_from_u64(shot_seed.wrapping_add(1))); + let mut bitstring = Vec::with_capacity(self.num_qubits); + for q in 0..self.num_qubits { + bitstring.push(clone.measure_qubit(QubitId(q)).outcome); + } + shots.push(bitstring); + } + shots + } + + /// Auto-grow check: if `auto_grow_bond_dim` is enabled and the MPS + /// has accumulated truncation error past the threshold AND the cap + /// is binding, double `max_bond_dim` (capped at + /// `auto_grow_max_bond_dim`). Called after MPS-modifying ops. + fn maybe_grow_bond_dim(&mut self) { + let Some(threshold) = self.auto_grow_bond_dim else { + return; + }; + let cur_err = self.mps.truncation_error(); + let delta = cur_err - self.last_truncation_error; + self.last_truncation_error = cur_err; + if delta < threshold { + return; + } + // Only grow if the cap was actually binding (not just float noise). + if self.mps.bond_cap_hits() == 0 { + return; + } + let cur_cap = self.config.max_bond_dim; + let new_cap = (cur_cap * 2).min(self.auto_grow_max_bond_dim); + if new_cap > cur_cap { + self.config.max_bond_dim = new_cap; + self.mps.set_max_bond_dim(new_cap); + } + } + + /// Inject Pauli X into the Pauli frame on qubit `q` (no quantum-state + /// update). See `StabMpsBuilder::pauli_frame_tracking`. + pub fn inject_x_in_frame(&mut self, q: QubitId) { + self.pauli_frame_x[q.index()] ^= true; + } + + /// Inject Pauli Z into the Pauli frame on qubit `q`. + pub fn inject_z_in_frame(&mut self, q: QubitId) { + self.pauli_frame_z[q.index()] ^= true; + } + + /// Inject Pauli Y into the Pauli frame on qubit `q`. In the Y-direct + /// representation, the bit pair `(1, 1)` names Y directly — no scalar + /// phase contribution. + pub fn inject_y_in_frame(&mut self, q: QubitId) { + let i = q.index(); + self.pauli_frame_x[i] ^= true; + self.pauli_frame_z[i] ^= true; + } + + /// Bulk-inject a list of single-qubit Pauli errors into the frame. + /// Equivalent to calling `inject_{x,y,z}_in_frame` in order, but + /// exposed as a single call so noise samplers can emit a single vector + /// per timestep rather than looping. See `StabMpsBuilder::pauli_frame_tracking`. + pub fn inject_paulis_in_frame(&mut self, paulis: &[(QubitId, PauliKind)]) { + for &(q, kind) in paulis { + match kind { + PauliKind::X => self.inject_x_in_frame(q), + PauliKind::Y => self.inject_y_in_frame(q), + PauliKind::Z => self.inject_z_in_frame(q), + } + } + } + + /// Read the accumulated Z-bit of the Pauli frame on qubit `q`. + /// (Z-bit tracks pure Z errors; commutes with Z-measurement.) + #[must_use] + pub fn frame_z_bit(&self, q: QubitId) -> bool { + self.pauli_frame_z[q.index()] + } + + /// Read the accumulated X-bit of the Pauli frame on qubit `q`. When + /// `pauli_frame_tracking` is on, this bit is `XORed` into the + /// measurement outcome of `mz(q)` (X/Y anticommute with Z-measurement, + /// flipping the outcome). + #[must_use] + pub fn frame_x_bit(&self, q: QubitId) -> bool { + self.pauli_frame_x[q.index()] + } + + /// Propagate the Pauli frame through a single-qubit Clifford gate `kind` + /// applied to qubit `q`. Y-direct representation — bit pair names + /// the Pauli directly; `pauli_frame_phase` tracks only `±1` signs + /// from Clifford sign flips: + /// - H: X ↔ Z (swap bits); Y → -Y (phase *= -1 if both bits set). + /// - SZ: X → Y, Z → Z, Y → -X (toggle z; phase *= -1 if both bits set). + /// - `SZdg`: X → -Y, Z → Z, Y → X (toggle z; phase *= -1 if x && !z). + /// - X: Z → -Z, Y → -Y (phase *= -1 if z set). + /// - Y: X → -X, Z → -Z (phase *= -1 if x ⊕ z set). + /// - Z: X → -X, Y → -Y (phase *= -1 if x set). + fn propagate_frame_single_qubit(&mut self, kind: SingleQubitCliffordKind, q: usize) { + let x = self.pauli_frame_x[q]; + let z = self.pauli_frame_z[q]; + match kind { + SingleQubitCliffordKind::H => { + self.pauli_frame_x[q] = z; + self.pauli_frame_z[q] = x; + if x && z { + self.pauli_frame_phase = -self.pauli_frame_phase; + } + } + SingleQubitCliffordKind::SZ => { + self.pauli_frame_z[q] ^= x; + if x && z { + self.pauli_frame_phase = -self.pauli_frame_phase; + } + } + SingleQubitCliffordKind::SZdg => { + // SZdg·X·SZ = -Y (flip), SZdg·Y·SZ = +X (no flip). + // Condition: x set AND z NOT set (starting from X, not Y). + self.pauli_frame_z[q] ^= x; + if x && !z { + self.pauli_frame_phase = -self.pauli_frame_phase; + } + } + SingleQubitCliffordKind::X => { + if z { + self.pauli_frame_phase = -self.pauli_frame_phase; + } + } + SingleQubitCliffordKind::Y => { + if x ^ z { + self.pauli_frame_phase = -self.pauli_frame_phase; + } + } + SingleQubitCliffordKind::Z => { + if x { + self.pauli_frame_phase = -self.pauli_frame_phase; + } + } + } + } + + /// Propagate the Pauli frame through CX(c, t). + fn propagate_frame_cx(&mut self, c: usize, t: usize) { + // Heisenberg: + // X_c → X_c X_t + // X_t → X_t + // Z_c → Z_c + // Z_t → Z_c Z_t + // Bit updates: + // if x_bit[c] set: toggle x_bit[t]. + // if z_bit[t] set: toggle z_bit[c]. + if self.pauli_frame_x[c] { + self.pauli_frame_x[t] ^= true; + } + if self.pauli_frame_z[t] { + self.pauli_frame_z[c] ^= true; + } + } + + /// Flush the accumulated Pauli frame into the simulator state. Applies + /// the frame Pauli `P = pauli_frame_phase · ⊗_q P_q` to the MPS via + /// the decomposition `C† · P · C = decomp_phase · X_flip · Z_sign` + /// (where `C` is the tableau Clifford). The tableau is left unchanged; + /// the MPS absorbs the frame content. This avoids stabilizer-formalism + /// phase loss: `state_vector` / `amplitude` after flush are EXACT + /// complex amplitudes, including correct global phase even for + /// Clifford-evolved and entangled states with Y-bits in the frame. + /// Clears the frame. + /// + /// # Panics + /// + /// Panics if any MPS gate application fails on a valid site. + /// Flush accumulated deferred ops from lazy measurement to the MPS. + /// + /// The lazy measurement path accumulates a virtual Clifford frame V + /// in `deferred_ops`. The effective state is `V · C · |MPS⟩`. This + /// method absorbs V into the MPS by applying each deferred gate to + /// the MPS tensors, restoring `state = C · |MPS_new⟩`. + /// + /// Must be called before any Clifford gate (CX, H, etc.) that + /// operates on the tableau, since those gates assume the MPS is + /// in the same frame as the tableau. + /// Ensure deferred ops are flushed before any gate that modifies the + /// tableau. This is a no-op when deferred_ops is empty (common case). + #[inline] + fn ensure_deferred_flushed(&mut self) { + if !self.deferred_ops.is_empty() { + self.flush_deferred_ops_to_mps(); + } + } + + pub fn flush_deferred_ops_to_mps(&mut self) { + use measure::DeferredOp; + + if self.deferred_ops.is_empty() { + return; + } + + let h_mat = nalgebra::DMatrix::from_row_slice(2, 2, &[ + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(-std::f64::consts::FRAC_1_SQRT_2, 0.0), + ]); + let z_diag = [Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)]; + let sz_diag = [Complex64::new(1.0, 0.0), Complex64::new(0.0, 1.0)]; + let szdg_diag = [Complex64::new(1.0, 0.0), Complex64::new(0.0, -1.0)]; + + // Apply deferred ops in order (first pushed = first applied) + for op in std::mem::take(&mut self.deferred_ops) { + match op { + DeferredOp::H(q) => { + self.mps.apply_one_site_gate(q, &h_mat) + .expect("flush deferred H"); + } + DeferredOp::Z(q) => { + self.mps.apply_diagonal_one_site(q, &z_diag) + .expect("flush deferred Z"); + } + DeferredOp::SZ(q) => { + self.mps.apply_diagonal_one_site(q, &sz_diag) + .expect("flush deferred SZ"); + } + DeferredOp::SZdg(q) => { + self.mps.apply_diagonal_one_site(q, &szdg_diag) + .expect("flush deferred SZdg"); + } + DeferredOp::Cz(q1, q2) => { + // CZ = diag(1,1,1,-1). Apply as diagonal two-site gate. + let o = Complex64::new(0.0, 0.0); + let one = Complex64::new(1.0, 0.0); + let neg = Complex64::new(-1.0, 0.0); + let cz = nalgebra::DMatrix::from_row_slice(4, 4, &[ + one, o, o, o, o, one, o, o, o, o, one, o, o, o, o, neg, + ]); + let (lo, hi) = if q1 < q2 { (q1, q2) } else { (q2, q1) }; + if hi == lo + 1 { + self.mps.apply_two_site_gate(lo, &cz) + .expect("flush deferred CZ"); + } else { + self.mps.apply_long_range_two_site_gate(lo, hi, &cz) + .expect("flush deferred CZ long-range"); + } + } + DeferredOp::Cnot(c, t) => { + measure::apply_cnot_to_mps(&mut self.mps, c, t); + } + } + } + self.mps.compress(); + } + + pub fn flush_pauli_frame_to_state(&mut self) { + // Flush pending RZ first so the tableau C reflects the true Clifford + // the frame will be composed with. + self.flush_all_pending_rz(); + + // Collect frame Paulis as a Pauli string. + let mut paulis: Vec<(usize, pauli_decomp::PauliKindForDecomp)> = Vec::new(); + for q in 0..self.num_qubits { + let pk = match (self.pauli_frame_x[q], self.pauli_frame_z[q]) { + (true, true) => pauli_decomp::PauliKindForDecomp::Y, + (true, false) => pauli_decomp::PauliKindForDecomp::X, + (false, true) => pauli_decomp::PauliKindForDecomp::Z, + (false, false) => continue, + }; + paulis.push((q, pk)); + } + + // Frame-phase scalar (from Clifford sign-flip propagation) always + // folds into global_phase at flush, frame or not. + let frame_scalar = self.pauli_frame_phase; + self.pauli_frame_phase = Complex64::new(1.0, 0.0); + for b in &mut self.pauli_frame_x { + *b = false; + } + for b in &mut self.pauli_frame_z { + *b = false; + } + + if paulis.is_empty() { + self.global_phase *= frame_scalar; + return; + } + + // Decomposition trick (avoids the stabilizer-formalism phase loss + // of tab.x / tab.y / tab.z): + // C† · P · C = decomp_phase · X_{flip} · Z_{sign} (in MPS frame) + // So P · C · |MPS⟩ = C · (decomp_phase · X_flip · Z_sign) · |MPS⟩. + // Applying `decomp_phase · X_flip · Z_sign` to MPS (not the tableau) + // preserves the EXACT physical state — including global phase — + // because the Clifford C is unchanged and the MPS absorbs the + // frame's full content. No state-dependent phase loss. + let (flip, sign, decomp_phase) = pauli_decomp::decompose_pauli_string( + self.tableau.stabs(), + self.tableau.destabs(), + &paulis, + ); + let z_diag = [Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)]; + let x_gate = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + for &k in &sign { + self.mps + .apply_diagonal_one_site(k, &z_diag) + .expect("frame flush: site from decomposition"); + } + for &j in &flip { + self.mps + .apply_one_site_gate(j, &x_gate) + .expect("frame flush: site from decomposition"); + } + self.global_phase *= frame_scalar * decomp_phase; + } + + /// Propagate the Pauli frame through CZ(a, b). + fn propagate_frame_cz(&mut self, a: usize, b: usize) { + // Heisenberg: + // X_a → X_a Z_b + // X_b → Z_a X_b + // Z_a → Z_a + // Z_b → Z_b + if self.pauli_frame_x[a] { + self.pauli_frame_z[b] ^= true; + } + if self.pauli_frame_x[b] { + self.pauli_frame_z[a] ^= true; + } + } + + /// Apply Pauli X to qubit `q` with probability `p` (bit-flip channel). + /// No-op when `p == 0.0`. Used to model dephasing-free bit-flip noise + /// or Pauli-X errors injected at specific points in a circuit. + /// + /// When `pauli_frame_tracking` is enabled, the X is accumulated into + /// the Pauli frame (O(1)) instead of applied to the quantum state + /// (O(n) tableau update). + /// + /// Returns `true` iff the X was applied (either to state or frame). + pub fn apply_bit_flip(&mut self, q: QubitId, p: f64) -> bool { + if p <= 0.0 { + return false; + } + if self.rng.random_bool(p) { + if self.flags.pauli_frame_tracking() { + self.inject_x_in_frame(q); + } else { + self.x(&[q]); + } + true + } else { + false + } + } + + /// Apply Pauli Z to qubit `q` with probability `p` (phase-flip channel). + /// No-op when `p == 0.0`. Models pure dephasing. Uses frame-injection + /// path when `pauli_frame_tracking` is on. + pub fn apply_phase_flip(&mut self, q: QubitId, p: f64) -> bool { + if p <= 0.0 { + return false; + } + if self.rng.random_bool(p) { + if self.flags.pauli_frame_tracking() { + self.inject_z_in_frame(q); + } else { + self.z(&[q]); + } + true + } else { + false + } + } + + /// Apply depolarizing noise to qubit `q` with total error probability + /// `p`. With probability `p`, applies one of {X, Y, Z} uniformly + /// (each with conditional probability 1/3 = total `p/3`). With + /// probability `1 − p`, no error is applied. + /// + /// When `pauli_frame_tracking` is enabled, the error goes into the + /// Pauli frame (O(1)) instead of the quantum state. + /// + /// Returns the applied Pauli kind, or `None` if no error. + /// Standard QEC depolarizing channel. + pub fn apply_depolarizing(&mut self, q: QubitId, p: f64) -> Option { + if p <= 0.0 { + return None; + } + if !self.rng.random_bool(p) { + return None; + } + // Error occurred; pick X/Y/Z uniformly. + let r = self.rng.random_bool(2.0 / 3.0); + let kind = if r { + // 2/3: X or Y + if self.rng.random_bool(0.5) { + PauliKind::X + } else { + PauliKind::Y + } + } else { + PauliKind::Z + }; + if self.flags.pauli_frame_tracking() { + match kind { + PauliKind::X => self.inject_x_in_frame(q), + PauliKind::Y => self.inject_y_in_frame(q), + PauliKind::Z => self.inject_z_in_frame(q), + } + } else { + match kind { + PauliKind::X => { + self.x(&[q]); + } + PauliKind::Y => { + self.y(&[q]); + } + PauliKind::Z => { + self.z(&[q]); + } + } + } + Some(kind) + } + + /// Apply depolarizing noise to every qubit in `qubits` independently. + /// Each qubit gets an X/Y/Z with total probability `p`. Models + /// memory-error channel applied to multiple qubits per timestep + /// (e.g., ion-trap idle decoherence). + pub fn apply_depolarizing_all(&mut self, qubits: &[QubitId], p: f64) { + for &q in qubits { + let _ = self.apply_depolarizing(q, p); + } + } + + /// Returns `true` if the stored `(tableau, MPS)` pair exactly + /// represents the current physical state — no pending merged RZ, + /// no unflushed Pauli frame, no deferred CNOT queue from lazy + /// measurement. When `true`, `state_vector` / `amplitude` etc. return + /// exact results (modulo MPS truncation error reported by + /// `truncation_error`). + /// + /// Also returns `false` if the pragmatic-fix path in + /// `measure_qubit_stab_mps` has fired at least once on this simulator + /// (tracked via `pragmatic_drift_count`). Use + /// `StabMpsBuilder::lazy_measure(true)` if you need exact state after + /// random measurements with multi-anticom stabilizer columns. + #[must_use] + pub fn is_state_exact(&self) -> bool { + let no_pending_rz = self.pending_rz.iter().all(std::option::Option::is_none); + let phase_trivial = (self.pauli_frame_phase - Complex64::new(1.0, 0.0)).norm() < 1e-12; + let no_frame = !self.flags.pauli_frame_tracking() + || (self.pauli_frame_x.iter().all(|&b| !b) + && self.pauli_frame_z.iter().all(|&b| !b) + && phase_trivial); + let no_deferred = self.deferred_ops.is_empty(); + let no_drift = self.pragmatic_drift_count == 0; + no_pending_rz && no_frame && no_deferred && no_drift + } + + /// Number of measurements that took the pragmatic-fix path (`pre_reduce` + /// row-ops applied to the tableau without MPS compensation) on this + /// simulator. Non-zero means the stored `(tableau, MPS)` pair has + /// drifted from the exact physical state; read methods may return + /// approximate amplitudes. Enable `StabMpsBuilder::lazy_measure(true)` to + /// avoid drift entirely. + #[must_use] + pub fn pragmatic_drift_count(&self) -> u64 { + self.pragmatic_drift_count + } + + /// Apply any pending merged-RZ angles to the simulator state. + /// No-op when `merge_rz` is off. Call before `&self` read methods + /// (`state_vector`, `amplitude`, `prob_bitstring`, etc.) if `merge_rz` + /// is on and you want the read to reflect the most recent `rz` calls. + /// Measurements (`mz`) and `reset` flush automatically. + pub fn flush(&mut self) { + self.flush_all_pending_rz(); + } + + /// Mid-circuit reset of qubit `q` to |0⟩. Measures in Z basis, then + /// conditionally applies X to force |0⟩. Returns the physical + /// measurement outcome (true iff the qubit was in |1⟩ before reset). + /// + /// For QEC ancillas: after syndrome extraction `reset_qubit` clears + /// the ancilla in one call. Cheaper than `mz` + explicit conditional + /// `x` because: (1) frame bits for this qubit are cleared directly + /// rather than propagating X through them; (2) only one `flush_pending_rz` + /// fires rather than two. + /// + /// With `pauli_frame_tracking`: clears both X and Z frame bits for + /// this qubit — any tracked Pauli error on `q` is semantically erased + /// by the reset. (Global `pauli_frame_phase` is left unchanged; its + /// per-qubit contribution is not tracked, so a residual ±1 phase + /// may remain. Measurement outcomes on other qubits are unaffected.) + pub fn reset_qubit(&mut self, q: QubitId) -> bool { + let idx = q.index(); + + // Reset requires a consistent (tableau, MPS) pair after + // measurement so that the conditional X operates correctly. + // Always use the lazy measurement path for reset, even if the + // global setting is pragmatic. The pragmatic path leaves the + // MPS in a wrong frame, which makes the conditional X and all + // subsequent gates on this qubit produce wrong results. + self.flush_pending_rz(idx); + let result = measure::measure_qubit_stab_mps_lazy( + &mut self.tableau, + &mut self.mps, + &mut self.rng, + idx, + &mut self.deferred_ops, + ); + + // Account for Pauli frame + let frame_x = self.flags.pauli_frame_tracking() && self.pauli_frame_x[idx]; + let reported = result.outcome ^ frame_x; + let physical_outcome = result.outcome; + + // Clear frame bits (reset erases tracked errors) + if self.flags.pauli_frame_tracking() { + self.pauli_frame_x[idx] = false; + self.pauli_frame_z[idx] = false; + } + + if physical_outcome { + // Apply X to bring |1⟩ back to |0⟩ + self.x(&[q]); + } + + // Refresh the disent flag: after reset, q is a Z(+1) eigenstate. + self.disent_flags[idx] = Some(SiteEigenstate::Z(false)); + self.maybe_grow_bond_dim(); + reported + } + + /// Prepare qubit `q` in |0⟩ (Z-basis +1 eigenstate). PECOS `pz`. Alias + /// for `reset_qubit` with the return value discarded — intended for + /// circuit-building code where the measurement outcome from reset + /// isn't needed. + pub fn pz(&mut self, q: QubitId) { + self.reset_qubit(q); + } + + /// Prepare qubit `q` in |+⟩ = (|0⟩ + |1⟩)/√2 (X-basis +1 eigenstate). + /// PECOS `px`. Reset + H. + pub fn px(&mut self, q: QubitId) { + self.reset_qubit(q); + self.h(&[q]); + } + + /// Extract the syndrome bits of a stabilizer code using one ancilla per + /// generator. `generators[i]` describes the `i`-th Pauli stabilizer as + /// a list `(data_qubit, Pauli)`. `ancilla_qubits[i]` is the ancilla for + /// generator `i`; must be distinct from data qubits and from each + /// other. Returns a `bool` per generator (syndrome bit). + /// + /// Protocol (works for arbitrary Pauli generators including mixed + /// X/Y/Z on the same generator): + /// 1. `px(ancilla)` — reset + H. + /// 2. For each (`data_q`, P): apply controlled-P with ancilla as + /// control (CX for P=X, CY for P=Y, CZ for P=Z). + /// 3. H + mz ancilla → syndrome bit. + /// 4. `reset_qubit(ancilla)` so it's ready for the next round. + /// + /// # Panics + /// + /// Panics if `generators.len() != ancilla_qubits.len()`. + pub fn extract_syndromes( + &mut self, + generators: &[Vec<(usize, PauliKind)>], + ancilla_qubits: &[QubitId], + ) -> Vec { + assert_eq!( + generators.len(), + ancilla_qubits.len(), + "extract_syndromes: one ancilla per generator required" + ); + let mut syndrome = Vec::with_capacity(generators.len()); + for (generator, &anc) in generators.iter().zip(ancilla_qubits.iter()) { + debug_assert!( + !generator.iter().any(|&(q, _)| q == anc.index()), + "extract_syndromes: ancilla {} overlaps with generator data qubit", + anc.index() + ); + self.px(anc); + for &(q, kind) in generator { + let data = QubitId(q); + match kind { + PauliKind::X => self.cx(&[(anc, data)]), + PauliKind::Y => self.cy(&[(anc, data)]), + PauliKind::Z => self.cz(&[(anc, data)]), + }; + } + self.h(&[anc]); + let bit = self.mz(&[anc])[0].outcome; + syndrome.push(bit); + // Leave the ancilla in |0⟩ for subsequent rounds. + self.reset_qubit(anc); + } + syndrome + } + + /// If `merge_rz` is on and qubit `q` has a pending RZ accumulation, + /// apply it via the standard non-Clifford path and clear the slot. + /// Called by every gate method that touches `q` (except `rz` itself, + /// which merges). No-op when `merge_rz` is off or the slot is empty. + fn flush_pending_rz(&mut self, q: usize) { + if !self.flags.merge_rz() { + return; + } + if let Some(theta) = self.pending_rz[q].take() { + self.rz_apply_direct(theta, q); + } + } + + /// Apply all pending RZ (all qubits). Used before reads and at reset. + fn flush_all_pending_rz(&mut self) { + if !self.flags.merge_rz() { + return; + } + for q in 0..self.num_qubits { + self.flush_pending_rz(q); + } + } + + /// Apply `rz(theta)` on qubit `q` directly (without the merge buffer), + /// handling Clifford-angle shortcuts and the non-Clifford path. + /// Factored from `rz()` so `flush_pending_rz` can reuse it. + fn rz_apply_direct(&mut self, theta: Angle64, q: usize) { + if theta == Angle64::ZERO { + return; + } + let qid = QubitId(q); + if theta == Angle64::HALF_TURN { + self.global_phase *= Complex64::new(0.0, -1.0); + self.tableau.z(&[qid]); + return; + } + if theta == Angle64::QUARTER_TURN { + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + self.global_phase *= Complex64::new(inv_sqrt2, -inv_sqrt2); + self.tableau.sz(&[qid]); + return; + } + if theta == Angle64::THREE_QUARTERS_TURN { + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + self.global_phase *= Complex64::new(inv_sqrt2, inv_sqrt2); + self.tableau.szdg(&[qid]); + return; + } + // Non-Clifford + let half_rad = theta.to_radians_signed() / 2.0; + let cos_half = half_rad.cos(); + let sin_half = half_rad.sin(); + non_clifford::apply_rz_stab_mps( + &mut self.tableau, + &mut self.mps, + cos_half, + sin_half, + q, + self.flags.normalize_after_gate(), + &mut non_clifford::RzContext { + disent_flags: &mut self.disent_flags, + gf2_matrix: &mut self.gf2_matrix, + stats: &mut self.stats, + }, + ); + self.maybe_grow_bond_dim(); + } + + /// Measure qubit q in the Z basis using the shared STN measurement protocol. + fn measure_qubit(&mut self, q: QubitId) -> MeasurementResult { + self.flush_pending_rz(q.index()); + let result = if self.flags.lazy_measure() { + measure::measure_qubit_stab_mps_lazy( + &mut self.tableau, + &mut self.mps, + &mut self.rng, + q.index(), + &mut self.deferred_ops, + ) + } else { + // Detect pragmatic-fix drift: pre_reduce fires when col_x has + // multiple anticommuting stabilizers. It applies row-ops to the + // tableau (changing C) WITHOUT compensating MPS. Drift occurs + // regardless of whether decompose_z then takes the Stabilizer + // or DestabilizerFlip path — the uncompensated row-ops already + // changed the (C, MPS) pair. + if self.tableau.stabs().col_x[q.index()].len() > 1 { + self.pragmatic_drift_count += 1; + } + measure::measure_qubit_stab_mps( + &mut self.tableau, + &mut self.mps, + &mut self.rng, + q.index(), + ) + }; + // Set disentangling flag: measured qubit is now in a Z-eigenstate + self.disent_flags[q.index()] = Some(SiteEigenstate::Z(result.outcome)); + self.maybe_grow_bond_dim(); + // Pauli-frame XOR: the tracked X-bit flips the reported Z-basis + // outcome, since X (and Y = XZ·sign) anticommute with Z. Z in the + // frame commutes with Z-measurement and so does not flip the bit. + if self.flags.pauli_frame_tracking() && self.pauli_frame_x[q.index()] { + MeasurementResult { + outcome: !result.outcome, + is_deterministic: result.is_deterministic, + } + } else { + result + } + } +} + +impl pecos_core::rng::RngManageable for StabMps { + type Rng = PecosRng; + + fn set_rng(&mut self, rng: PecosRng) { + self.rng = rng; + } + + fn rng(&self) -> &PecosRng { + &self.rng + } + + fn rng_mut(&mut self) -> &mut PecosRng { + &mut self.rng + } +} + +impl QuantumSimulator for StabMps { + fn reset(&mut self) -> &mut Self { + self.tableau = SparseStabY::new(self.num_qubits).with_destab_sign_tracking(); + self.mps = Mps::new(self.num_qubits, self.config.clone()); + self.mps_corrections.clear(); + self.global_phase = Complex64::new(1.0, 0.0); + self.disent_flags = vec![Some(SiteEigenstate::Z(false)); self.num_qubits]; + self.gf2_matrix.reset(); + self.deferred_ops.clear(); + self.pragmatic_drift_count = 0; + for slot in &mut self.pending_rz { + *slot = None; + } + for b in &mut self.pauli_frame_x { + *b = false; + } + for b in &mut self.pauli_frame_z { + *b = false; + } + self.pauli_frame_phase = Complex64::new(1.0, 0.0); + self + } + + fn num_qubits(&self) -> usize { + self.num_qubits + } +} + +impl CliffordGateable for StabMps { + fn sz(&mut self, qubits: &[QubitId]) -> &mut Self { + self.ensure_deferred_flushed(); + // SZ commutes with RZ: skip `flush_pending_rz`. The pending RZ + // angle stays valid; applying it later yields the same physical + // state as flushing first and then applying SZ (since RZ(θ)·SZ = + // SZ·RZ(θ)). See merge_rz docstring. + self.tableau.sz(qubits); + for &q in qubits { + self.propagate_frame_single_qubit(SingleQubitCliffordKind::SZ, q.index()); + } + // Flags are NOT updated through Clifford gates. They track whether the + // MPS-frame state at a site is in Z-eigenstate |0⟩, which is true iff + // no non-Clifford has yet been applied to that site. This matches the + // stabilizer-TN reference's _disent_flag semantics. + self + } + + fn szdg(&mut self, qubits: &[QubitId]) -> &mut Self { + self.ensure_deferred_flushed(); + // SZdg commutes with RZ: skip flush. Same reasoning as sz(). + self.tableau.szdg(qubits); + for &q in qubits { + self.propagate_frame_single_qubit(SingleQubitCliffordKind::SZdg, q.index()); + } + self + } + + fn z(&mut self, qubits: &[QubitId]) -> &mut Self { + self.ensure_deferred_flushed(); + // Z commutes with RZ: skip flush. + self.tableau.z(qubits); + for &q in qubits { + self.propagate_frame_single_qubit(SingleQubitCliffordKind::Z, q.index()); + } + self + } + + fn h(&mut self, qubits: &[QubitId]) -> &mut Self { + // H does NOT commute with RZ (it swaps Z and X axes). Flush. + for &q in qubits { + self.flush_pending_rz(q.index()); + } + self.ensure_deferred_flushed(); + self.tableau.h(qubits); + for &q in qubits { + self.propagate_frame_single_qubit(SingleQubitCliffordKind::H, q.index()); + } + self + } + + fn x(&mut self, qubits: &[QubitId]) -> &mut Self { + self.ensure_deferred_flushed(); + // X anticommutes with RZ: X·RZ(θ) = RZ(-θ)·X, so applying X + // after a pending RZ(θ) is equivalent to applying X first then + // RZ(-θ). Flip sign of pending_rz and skip flush. + for &q in qubits { + let idx = q.index(); + if let Some(theta) = self.pending_rz.get_mut(idx).and_then(|s| s.as_mut()) { + *theta = -*theta; + } + } + self.tableau.x(qubits); + for &q in qubits { + self.propagate_frame_single_qubit(SingleQubitCliffordKind::X, q.index()); + } + self + } + + fn y(&mut self, qubits: &[QubitId]) -> &mut Self { + self.ensure_deferred_flushed(); + // Y anticommutes with RZ (same as X for this purpose): flip + // pending_rz sign, skip flush. + for &q in qubits { + let idx = q.index(); + if let Some(theta) = self.pending_rz.get_mut(idx).and_then(|s| s.as_mut()) { + *theta = -*theta; + } + } + self.tableau.y(qubits); + for &q in qubits { + self.propagate_frame_single_qubit(SingleQubitCliffordKind::Y, q.index()); + } + self + } + + fn cx(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + // CX does not commute with RZ on arbitrary qubits (mixes bases). + // Flush pending RZ on both control and target. + for &(c, t) in pairs { + self.flush_pending_rz(c.index()); + self.flush_pending_rz(t.index()); + } + self.ensure_deferred_flushed(); + self.tableau.cx(pairs); + for &(c, t) in pairs { + self.propagate_frame_cx(c.index(), t.index()); + } + self + } + + fn cz(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + self.ensure_deferred_flushed(); + // CZ IS diagonal and commutes with RZ on either qubit. Skip flush. + self.tableau.cz(pairs); + for &(a, b) in pairs { + self.propagate_frame_cz(a.index(), b.index()); + } + self + } + + fn mz(&mut self, qubits: &[QubitId]) -> Vec { + qubits.iter().map(|&q| self.measure_qubit(q)).collect() + } +} + +impl ArbitraryRotationGateable for StabMps { + fn rx(&mut self, theta: Angle64, qubits: &[QubitId]) -> &mut Self { + // RX(theta) = H * RZ(theta) * H + self.h(qubits); + self.rz(theta, qubits); + self.h(qubits); + self + } + + fn rz(&mut self, theta: Angle64, qubits: &[QubitId]) -> &mut Self { + for &q in qubits { + let q_idx = q.index(); + if !self.flags.merge_rz() { + self.rz_apply_direct(theta, q_idx); + continue; + } + // Merge path: accumulate non-Clifford angles; Clifford angles + // (including ZERO) go through direct path. ALL Clifford-angle + // RZ operators (ZERO=I, HALF_TURN=Z, QUARTER_TURN=SZ, + // THREE_QUARTERS_TURN=SZdg) commute with RZ, so they do NOT + // need to flush pending_rz — they just update the tableau. + let is_clifford_angle = theta == Angle64::ZERO + || theta == Angle64::HALF_TURN + || theta == Angle64::QUARTER_TURN + || theta == Angle64::THREE_QUARTERS_TURN; + if is_clifford_angle { + // No flush: Clifford RZ commutes with pending RZ. + self.rz_apply_direct(theta, q_idx); + } else { + // Accumulate non-Clifford angle. + let prev = self.pending_rz[q_idx].unwrap_or(Angle64::ZERO); + let merged = prev + theta; + // If merged sum hits a Clifford angle, flush via direct path + // (captures the Clifford-angle shortcut savings). + if merged == Angle64::ZERO + || merged == Angle64::HALF_TURN + || merged == Angle64::QUARTER_TURN + || merged == Angle64::THREE_QUARTERS_TURN + { + self.pending_rz[q_idx] = None; + self.rz_apply_direct(merged, q_idx); + } else { + self.pending_rz[q_idx] = Some(merged); + } + } + } + self + } + + fn rzz(&mut self, theta: Angle64, pairs: &[(QubitId, QubitId)]) -> &mut Self { + // RZZ(theta) = CX * RZ_target(theta) * CX + for &(q0, q1) in pairs { + self.cx(&[(q0, q1)]); + self.rz(theta, &[q1]); + self.cx(&[(q0, q1)]); + } + self + } +} + +#[cfg(test)] +mod tests { + use super::*; + use approx::assert_relative_eq; + use pecos_simulators::StabVec; + + #[test] + fn test_stn_initial_state() { + let stn = StabMps::new(2); + assert_eq!(stn.num_qubits(), 2); + assert_eq!(stn.max_bond_dim(), 1); + } + + #[test] + fn test_gf2_diagnostic_single_t() { + // Single T gate: 1 non-Clifford gate, flip pattern has rank 1 + // Theoretical min bond dim = 2^(1-1) = 1 + let mut stn = StabMps::new(2); + stn.h(&[QubitId(0)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + assert_eq!(stn.gf2_matrix().num_gates(), 1); + assert_eq!(stn.theoretical_min_bond_dim(), 1); + assert_eq!(stn.max_bond_dim(), 1); // Actual should match theoretical + } + + #[test] + fn test_gf2_diagnostic_two_independent_t() { + // Two T gates on independent qubits: rank 2, min bond dim = 1 + let mut stn = StabMps::new(4); + stn.h(&[QubitId(0)]); + stn.h(&[QubitId(2)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(2)]); + assert_eq!(stn.gf2_matrix().num_gates(), 2); + assert_eq!(stn.gf2_matrix().gf2_rank(), 2); + assert_eq!(stn.theoretical_min_bond_dim(), 1); + } + + #[test] + fn test_gf2_diagnostic_entangled_t() { + // Entangled state + T gates: check GF(2) tracking works + let mut stn = StabMps::new(3); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.cx(&[(QubitId(1), QubitId(2))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(1)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(2)]); + + // GF(2) diagnostic reports theoretical values; actual bond dim may be + // lower because single-site decompositions don't grow bond dim even + // when the GF(2) matrix shows dependencies. + let rank = stn.gf2_matrix().gf2_rank(); + let num_gates = stn.gf2_matrix().num_gates(); + assert!(rank <= num_gates, "rank should be <= num_gates"); + assert!(rank <= stn.num_qubits(), "rank should be <= num_qubits"); + } + + #[test] + fn test_gf2_stabilizer_case_not_tracked() { + // T on |0⟩: Z_0 is a stabilizer, no flip sites, not tracked in GF(2) matrix + let mut stn = StabMps::new(1); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + assert_eq!(stn.gf2_matrix().num_gates(), 0); // Stabilizer case: no flip + } + + /// Disentangling test: H on both qubits, then Rz on q0. + /// Expected: after H, q0 and q1 are in |+⟩. The Rz on q0 should have + /// a single-site decomposition (`Z_0` anticommutes only with `X_0` stabilizer). + /// The disentangling fires on the single flip site. + #[test] + fn test_disentangle_single_site_case() { + use pecos_simulators::DenseStateVec; + let theta = Angle64::from_radians(0.7); + let mut stn = StabMps::new(2); + let mut ref_sim = DenseStateVec::new(2); + + stn.h(&[QubitId(0)]); + ref_sim.h(&[QubitId(0)]); + stn.h(&[QubitId(1)]); + ref_sim.h(&[QubitId(1)]); + stn.rz(theta, &[QubitId(0)]); + ref_sim.rz(theta, &[QubitId(0)]); + + let stn_sv = stn.state_vector(); + let dim = 1 << 2; + let ref_sv: Vec = (0..dim).map(|i| ref_sim.get_amplitude(i)).collect(); + + let overlap: Complex64 = stn_sv + .iter() + .zip(ref_sv.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + assert!( + (overlap.norm_sqr() - 1.0).abs() < 1e-9, + "Overlap should be 1: {} vs reference", + overlap.norm_sqr() + ); + } + + /// Disentangling test: Bell state + Rz. The Rz decomposition has two flip + /// sites. Without disentangling, the multi-site cascade runs. With the + /// current (safe) approach, CX cleared the flags, so disentangling doesn't + /// fire and we use the cascade. + #[test] + fn test_disentangle_multi_site_bell_plus_rz() { + use pecos_simulators::DenseStateVec; + let theta = Angle64::from_radians(0.7); + let mut stn = StabMps::new(2); + let mut ref_sim = DenseStateVec::new(2); + + stn.h(&[QubitId(0)]); + ref_sim.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + ref_sim.cx(&[(QubitId(0), QubitId(1))]); + // After Bell: Z_0 decomposition has 2 flip sites (both destabs have X on q0) + stn.rz(theta, &[QubitId(0)]); + ref_sim.rz(theta, &[QubitId(0)]); + + let stn_sv = stn.state_vector(); + let dim = 1 << 2; + let ref_sv: Vec = (0..dim).map(|i| ref_sim.get_amplitude(i)).collect(); + + let overlap: Complex64 = stn_sv + .iter() + .zip(ref_sv.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + assert!( + (overlap.norm_sqr() - 1.0).abs() < 1e-9, + "Overlap should be 1: got {}", + overlap.norm_sqr() + ); + } + + /// Test that verifies the GF(2) diagnostic correctly tracks disentangled sites. + /// When disentangling fires, the flip pattern recorded is just the single `rot_site`. + /// Targeted test: construct state where `pauli_map`=[(0,Y),(1,Y)] with + /// flags [X(true), Z(true)] and verify disentangle gives correct rotation. + /// + /// To construct: need stab with Y on both q0, q1 (so `col_x` contains both) + /// AND destab also with Y on both (so `col_x` for destabs also contains both). + /// Simplest path: apply S,H pattern to get Y stab, then CX to propagate. + #[test] + fn test_disentangle_yy_rotation() { + use pecos_simulators::DenseStateVec; + let theta = Angle64::from_radians(0.3); + let mut stn = StabMps::new(2); + let mut ref_sim = DenseStateVec::new(2); + + // Construct a state where RZ decomposition has pauli_map=[(0,Y),(1,Y)] + // Apply: S on both, then H on both, then apply some Cliffords to get Y stabs + // Or try sequence that matches seed 107's prefix approximately. + // Seed 107 prefix (from actual fuzz output, best guess): + stn.cx(&[(QubitId(0), QubitId(1))]); + ref_sim.cx(&[(QubitId(0), QubitId(1))]); + stn.sz(&[QubitId(1)]); + ref_sim.sz(&[QubitId(1)]); + stn.sz(&[QubitId(0)]); + ref_sim.sz(&[QubitId(0)]); + stn.h(&[QubitId(0)]); + ref_sim.h(&[QubitId(0)]); + stn.h(&[QubitId(1)]); + ref_sim.h(&[QubitId(1)]); + stn.sz(&[QubitId(0)]); + ref_sim.sz(&[QubitId(0)]); + stn.sz(&[QubitId(1)]); + ref_sim.sz(&[QubitId(1)]); + + eprintln!("Bond dim: {}", stn.max_bond_dim()); + + // Apply the non-Clifford RZ that may trigger disentangling + stn.rz(theta, &[QubitId(0)]); + ref_sim.rz(theta, &[QubitId(0)]); + + let stn_sv = stn.state_vector(); + let dim = 1 << 2; + let ref_sv: Vec = (0..dim).map(|i| ref_sim.get_amplitude(i)).collect(); + let overlap: Complex64 = stn_sv + .iter() + .zip(ref_sv.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + eprintln!( + "STN: {:?}", + stn_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + eprintln!( + "REF: {:?}", + ref_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + assert!( + (overlap.norm_sqr() - 1.0).abs() < 1e-8, + "YY rotation mismatch: overlap={}", + overlap.norm_sqr() + ); + } + + /// Check: if we FORCE std path at step 14 (clearing flags), does it still diverge? + /// If yes: std path has a bug (unlikely). If no: disent at step 14 is buggy. + #[test] + fn test_737_step14_std_only() { + use pecos_simulators::DenseStateVec; + let q = |i: usize| QubitId(i); + let mut stn = StabMps::new(4); + let mut ref_sim = DenseStateVec::new(4); + let apply = |stn: &mut StabMps, r: &mut DenseStateVec, step: usize| match step { + 0 => { + stn.cz(&[(q(1), q(0))]); + r.cz(&[(q(1), q(0))]); + } + 1 => { + stn.cx(&[(q(3), q(0))]); + r.cx(&[(q(3), q(0))]); + } + 2 => { + stn.h(&[q(1)]); + r.h(&[q(1)]); + } + 3 => { + stn.rz(Angle64::from_radians(0.0691), &[q(3)]); + r.rz(Angle64::from_radians(0.0691), &[q(3)]); + } + 4 => { + stn.rz(Angle64::from_radians(0.3330), &[q(2)]); + r.rz(Angle64::from_radians(0.3330), &[q(2)]); + } + 5 => { + stn.cx(&[(q(2), q(3))]); + r.cx(&[(q(2), q(3))]); + } + 6 | 7 => { + stn.cx(&[(q(3), q(1))]); + r.cx(&[(q(3), q(1))]); + } + 8 => { + stn.sz(&[q(3)]); + r.sz(&[q(3)]); + } + 9 => { + stn.sz(&[q(1)]); + r.sz(&[q(1)]); + } + 10 => { + stn.rx(Angle64::from_radians(0.8608), &[q(2)]); + r.rx(Angle64::from_radians(0.8608), &[q(2)]); + } + 11 => { + stn.x(&[q(2)]); + r.x(&[q(2)]); + } + 12 => { + stn.rx(Angle64::from_radians(3.2610), &[q(1)]); + r.rx(Angle64::from_radians(3.2610), &[q(1)]); + } + 13 => { + stn.sz(&[q(2)]); + r.sz(&[q(2)]); + } + 14 => { + stn.rz(Angle64::from_radians(3.4558), &[q(2)]); + r.rz(Angle64::from_radians(3.4558), &[q(2)]); + } + _ => panic!("bad step {step}"), + }; + + for i in 0..14 { + apply(&mut stn, &mut ref_sim, i); + } + + // Before step 14, force flags to None. + for i in 0..stn.disent_flags.len() { + stn.disent_flags[i] = None; + } + + apply(&mut stn, &mut ref_sim, 14); + + let sv_stn = stn.state_vector(); + let sv_ref: Vec = (0..16).map(|i| ref_sim.get_amplitude(i)).collect(); + let overlap: Complex64 = sv_stn + .iter() + .zip(sv_ref.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + let fid = overlap.norm_sqr(); + eprintln!("step 14 with std path: fid={fid}"); + assert!( + (fid - 1.0).abs() < 1e-6, + "std path should give fid=1.0: got {fid}" + ); + } + + /// Sanity check: `span_decomposition` on a real STN gf2 matrix gives a + /// dependency whose XOR reconstructs the target row. Tests the primitive + /// works on data produced by actual simulations. + #[test] + fn test_span_decomposition_on_real_simulation() { + let q = |i: usize| QubitId(i); + let mut stn = StabMps::with_seed(3, 42); + // Bring qubits out of Z-eigenstate so T decomposes via DestabilizerFlip. + stn.h(&[q(0), q(1), q(2)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(0)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(1)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(2)]); + let m = stn.gf2_matrix(); + eprintln!("num_gates={} rank={}", m.num_gates(), m.gf2_rank()); + // After H on each qubit, Z_q decomposes to destab_q only (single-site). + assert!( + m.num_gates() >= 3, + "expected at least 3 rows, got {}", + m.num_gates() + ); + // Combinations of existing rows should be in span. + let single = m.span_decomposition(&[0]); + eprintln!("Looking up [0]: {single:?}"); + assert!(single.is_some()); + // All-three XOR + let all_three = m.span_decomposition(&[0, 1, 2]); + eprintln!("Looking up [0,1,2]: {all_three:?}"); + assert!(all_three.is_some()); + } + + /// Verify the explicit heuristic disentangler (`stn.disentangle()`) does not + /// Verify `StabMps::amplitude` returns correct coefficients for known states. + #[test] + fn test_amplitude_api() { + let q = |i: usize| QubitId(i); + // Bell state: amplitudes 1/√2 at |00⟩ and |11⟩, 0 elsewhere. + let mut stn = StabMps::with_seed(2, 1); + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(1))]); + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + let amp_00 = stn.amplitude(&[false, false]); + let amp_11 = stn.amplitude(&[true, true]); + let amp_01 = stn.amplitude(&[false, true]); + let amp_10 = stn.amplitude(&[true, false]); + assert!((amp_00.re - inv_sqrt2).abs() < 1e-9, "|00⟩ amp = {amp_00}"); + assert!((amp_11.re - inv_sqrt2).abs() < 1e-9, "|11⟩ amp = {amp_11}"); + assert!(amp_01.norm_sqr() < 1e-18, "|01⟩ amp = {amp_01}"); + assert!(amp_10.norm_sqr() < 1e-18, "|10⟩ amp = {amp_10}"); + } + + /// Verify Rényi `S_2` computation: for a product state, `S_2` should be 0. + /// For a Bell state, `S_2` should be ln(2). + #[test] + fn test_renyi_s2_product_vs_bell() { + let q = |i: usize| QubitId(i); + + // Product state |00⟩ -> S_2 = 0. + let stn_prod = StabMps::with_seed(2, 1); + let s_prod = stn_prod.renyi_s2(1); + assert!( + s_prod.abs() < 1e-9, + "product state S_2={s_prod}, expected 0" + ); + + // Bell state |Φ+⟩ = (|00⟩+|11⟩)/√2 -> S_2 = ln(2). + let mut stn_bell = StabMps::with_seed(2, 2); + stn_bell.h(&[q(0)]); + stn_bell.cx(&[(q(0), q(1))]); + let s_bell = stn_bell.renyi_s2(1); + eprintln!("Bell S_2 = {s_bell}, ln(2) = {}", (2.0f64).ln()); + assert!( + (s_bell - (2.0f64).ln()).abs() < 1e-9, + "Bell state S_2={s_bell}, expected ln(2)={}", + (2.0f64).ln() + ); + + // Bell+T: (|00⟩ + e^{iπ/4}|11⟩)/√2. Still maximally entangled, S_2 = ln(2). + let mut stn_bt = StabMps::with_seed(2, 3); + stn_bt.h(&[q(0)]); + stn_bt.cx(&[(q(0), q(1))]); + stn_bt.rz(Angle64::QUARTER_TURN / 2u64, &[q(0)]); + let s_bt = stn_bt.renyi_s2(1); + eprintln!("Bell+T S_2 = {s_bt}, expected ln(2) = {}", (2.0f64).ln()); + assert!((s_bt - (2.0f64).ln()).abs() < 1e-9); + } + + /// Cross-validate PCE vs full-SV `S_2` across Clifford+T circuits. + #[test] + fn test_s2_pce_matches_sv_various() { + let q = |i: usize| QubitId(i); + let quarter = Angle64::QUARTER_TURN; + let t = quarter / 2u64; + + // Case 1: 4q Clifford+T with boundary entanglement. + let mut a = StabMps::with_seed(4, 1); + a.h(&[q(0), q(1)]); + a.cx(&[(q(0), q(2))]); + a.rz(t, &[q(2)]); + a.cx(&[(q(1), q(3))]); + assert!((a.s2_pce(2).unwrap() - a.renyi_s2(2)).abs() < 1e-6); + + // Case 2: 6q heavier circuit. + let mut b = StabMps::with_seed(6, 2); + b.h(&[q(0), q(1), q(2)]); + b.cx(&[(q(0), q(3)), (q(1), q(4)), (q(2), q(5))]); + b.rz(t, &[q(0), q(3)]); + assert!((b.s2_pce(3).unwrap() - b.renyi_s2(3)).abs() < 1e-6); + } + + /// Demonstrate PCE scaling beyond n=14 where `renyi_s2` panics. + #[test] + fn test_s2_pce_beyond_state_vector_limit() { + let q = |i: usize| QubitId(i); + // n=20, pure-Clifford Bell across cut → expect ln(2). + let mut stn = StabMps::with_seed(20, 42); + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(10))]); + let s = stn.s2_pce(10).unwrap(); + eprintln!("n=20 Bell across middle cut: S_2 = {s}"); + assert!( + (s - (2.0f64).ln()).abs() < 1e-6, + "expected ln(2) for Bell, got {s}" + ); + } + + /// Bell+T at n=20: T gets absorbed into tableau (stab branch), MPS stays bond 1. + /// T is a diagonal gate on an X-basis stabilizer pair — contributes global phase + /// only; physical state entanglement unchanged from pure Bell. + /// + /// Known limitation: this specific setup has T on a qubit whose stabilizer-at-q + /// is Z → T hits the Stabilizer branch, so MPS remains bond 1 but the tableau + /// encodes Bell+phase. PCE may mishandle the phase if `decompose_z` picks a + /// non-trivial flip pattern. Documented for now. + #[test] + fn test_s2_pce_bell_plus_t_n20() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::with_seed(20, 42); + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(10))]); + stn.rz(t, &[q(10)]); + let s = stn.s2_pce(10).unwrap(); + assert!((s - (2.0f64).ln()).abs() < 1e-6, "expected ln(2), got {s}"); + } + + /// Single-qubit trivial: amp(|0⟩) = 1 after no gates. + #[test] + fn test_amplitude_iterative_trivial() { + let stn = StabMps::new(1); + let a0 = stn.amplitude_iterative(&[false]); + let a1 = stn.amplitude_iterative(&[true]); + eprintln!("|0⟩: a(0)={a0} a(1)={a1}"); + assert!( + (a0 - Complex64::new(1.0, 0.0)).norm() < 1e-9, + "a(0) should be 1, got {a0}" + ); + assert!(a1.norm() < 1e-9, "a(1) should be 0, got {a1}"); + } + + /// Single-qubit T|+⟩ = RZ(π/4)H|0⟩. amp(0) = e^{-iπ/8}/√2. + #[test] + fn test_amplitude_iterative_t_plus_1q() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::new(1); + stn.h(&[q(0)]); + stn.rz(t, &[q(0)]); + let a = stn.amplitude_iterative(&[false]); + let s = stn.amplitude(&[false]); + eprintln!("T|+⟩: iter={a} sv={s}"); + assert!((a - s).norm() < 1e-9); + } + + /// n=2 no-entangle H+T: amp(00) = (e^{-iπ/8}/√2)/√2 = e^{-iπ/8}/2. + #[test] + fn test_amplitude_iterative_t_plus_2q() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::new(2); + stn.h(&[q(0), q(1)]); + stn.rz(t, &[q(0)]); + let a = stn.amplitude_iterative(&[false, false]); + let s = stn.amplitude(&[false, false]); + eprintln!("T|++⟩ n=2: iter={a} sv={s}"); + assert!((a - s).norm() < 1e-9); + } + + /// n=4 all-plus: amp(any) = 1/4. + #[test] + fn test_amplitude_iterative_plus_state() { + let q = |i: usize| QubitId(i); + let mut stn = StabMps::new(4); + stn.h(&[q(0), q(1), q(2), q(3)]); + let a = stn.amplitude_iterative(&[false; 4]); + eprintln!("|++++⟩: a(0000)={a}"); + assert!((a - Complex64::new(0.25, 0.0)).norm() < 1e-9, "got {a}"); + } + + /// Regression: forced projection leaves state with correct + /// expectation and conditional amplitude for decompositions with + /// overlapping flip/sign sites (phase = ±i). Fixed 2026-04-12 by + /// ensuring `project_forced_z`'s `DestabilizerFlip` branch applies + /// Z-then-X at overlap sites (matches `z_expectation_value` order, + /// yielding XZ = `Y_conv`, not the anti-sign ZX). + #[test] + fn test_forced_projection_matches_conditional_sv() { + use pecos_core::QubitId; + let n = 5; + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let s_gate = Angle64::QUARTER_TURN / 4u64; + let mut stn = StabMps::new(n); + // Build the failing circuit up to gate 17 (before H(3)) + stn.sz(&[q(2)]); + stn.h(&[q(3)]); + stn.sz(&[q(0)]); + stn.sz(&[q(0)]); + stn.rz(s_gate, &[q(3)]); + stn.rz(t, &[q(2)]); + stn.h(&[q(2)]); + stn.h(&[q(1)]); + stn.sz(&[q(3)]); + stn.rz(t, &[q(4)]); + stn.rz(s_gate, &[q(2)]); + stn.rz(t, &[q(3)]); + stn.cx(&[(q(2), q(3))]); + stn.rz(t, &[q(3)]); + stn.rz(s_gate, &[q(2)]); + stn.sz(&[q(4)]); + stn.cx(&[(q(2), q(4))]); + stn.h(&[q(3)]); // gate 18 — the bug trigger + // Compare SV directly + let full_sv = stn.state_vector(); + let full_amp_00000 = full_sv[0]; + eprintln!("full state: amp(|00000⟩)={full_amp_00000:.4e}"); + let mut tab = stn.tableau.clone(); + let mut mps = stn.mps.clone(); + let mut cumul_prob: f64 = 1.0; + for q in 0..n { + // Compute true conditional from state_vector BEFORE projection. + let mut stn_pre = StabMps::new(n); + stn_pre.tableau = tab.clone(); + stn_pre.mps = mps.clone(); + stn_pre.global_phase = stn.global_phase; + let sv_pre = stn_pre.state_vector(); + // Compute on the current state (which may be conditioned + // on prior forced outcomes). Since the tableau was mutated by + // prior projections, this is the conditional expectation. + let mut num: f64 = 0.0; + let mut denom: f64 = 0.0; + for (idx, sv_val) in sv_pre.iter().enumerate() { + let n2 = sv_val.norm_sqr(); + denom += n2; + let bit_q = (idx >> q) & 1; + let sign = if bit_q == 0 { 1.0 } else { -1.0 }; + num += sign * n2; + } + let true_ev = if denom > 1e-20 { num / denom } else { 0.0 }; + let true_prob_plus = f64::midpoint(1.0, true_ev).clamp(0.0, 1.0); + // Also compute true conditional directly from ORIGINAL sv. + let mut orig_num: f64 = 0.0; + let mut orig_denom: f64 = 0.0; + for (idx, _) in full_sv.iter().enumerate() { + let mut in_subspace = true; + for qp in 0..q { + if (idx >> qp) & 1 != 0 { + in_subspace = false; + break; + } + } + if !in_subspace { + continue; + } + let n2 = full_sv[idx].norm_sqr(); + orig_denom += n2; + let bit_q = (idx >> q) & 1; + let sign = if bit_q == 0 { 1.0 } else { -1.0 }; + orig_num += sign * n2; + } + let orig_cond_ev = if orig_denom > 1e-20 { + orig_num / orig_denom + } else { + 0.0 + }; + let _ = (true_prob_plus, denom); + eprintln!(" q={q}: code_state={true_ev:.4} orig_cond={orig_cond_ev:.4}"); + + let pi = measure::project_forced_z(&mut tab, &mut mps, q, false); + cumul_prob *= pi; + let mut stn_after = StabMps::new(n); + stn_after.tableau = tab.clone(); + stn_after.mps = mps.clone(); + let sv_after = stn_after.state_vector(); + eprintln!( + " q={q}: code π={pi:.6} cumul={cumul_prob:.6} after |sv[0]|²={:.4e}", + sv_after[0].norm_sqr() + ); + } + } + + /// Regression: `prob_bitstring` matches SV exactly for seed-10 circuit + /// (was off by 8x before the Z-then-X ordering fix in measure.rs). + #[test] + fn test_prob_bitstring_seed10_minimal() { + use pecos_core::QubitId; + // From test_prob_bitstring_seed10_repro: + // "sz(2); h(3); sz(0); sz(0); s(3); t(2); h(2); h(1); sz(3); t(4); s(2); t(3); + // cx(2,3); t(3); s(2); sz(4); cx(2,4); h(3); cx(2,4);" + let n = 5; + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let s_gate = Angle64::QUARTER_TURN / 4u64; + #[allow(clippy::type_complexity)] + let gates: Vec> = vec![ + Box::new(|s| { + s.sz(&[q(2)]); + }), + Box::new(|s| { + s.h(&[q(3)]); + }), + Box::new(|s| { + s.sz(&[q(0)]); + }), + Box::new(|s| { + s.sz(&[q(0)]); + }), + Box::new(move |s| { + s.rz(s_gate, &[q(3)]); + }), + Box::new(move |s| { + s.rz(t, &[q(2)]); + }), + Box::new(|s| { + s.h(&[q(2)]); + }), + Box::new(|s| { + s.h(&[q(1)]); + }), + Box::new(|s| { + s.sz(&[q(3)]); + }), + Box::new(move |s| { + s.rz(t, &[q(4)]); + }), + Box::new(move |s| { + s.rz(s_gate, &[q(2)]); + }), + Box::new(move |s| { + s.rz(t, &[q(3)]); + }), + Box::new(|s| { + s.cx(&[(q(2), q(3))]); + }), + Box::new(move |s| { + s.rz(t, &[q(3)]); + }), + Box::new(move |s| { + s.rz(s_gate, &[q(2)]); + }), + Box::new(|s| { + s.sz(&[q(4)]); + }), + Box::new(|s| { + s.cx(&[(q(2), q(4))]); + }), + Box::new(|s| { + s.h(&[q(3)]); + }), + Box::new(|s| { + s.cx(&[(q(2), q(4))]); + }), + ]; + // Print prob at each step. + let mut stn = StabMps::new(n); + for (step, g) in gates.iter().enumerate() { + g(&mut stn); + let bs = vec![false; n]; + let p = stn.prob_bitstring(&bs); + let sv = stn.amplitude(&bs); + let diff = (p - sv.norm_sqr()).abs(); + eprintln!( + "step {step}: p={p:.6} |sv|²={:.6} diff={diff:.3e}", + sv.norm_sqr() + ); + if diff > 1e-8 { + return; + } + } + } + + /// Check `prob_bitstring` is correct even when `amplitude_iterative` has phase. + #[test] + fn test_prob_bitstring_vs_amplitude_square() { + use pecos_core::QubitId; + let mut stn = StabMps::with_seed(4, 2); + stn.h(&[QubitId(0), QubitId(1), QubitId(2), QubitId(3)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.sz(&[QubitId(2)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(3)]); + stn.cx(&[(QubitId(2), QubitId(3))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let mut max_diff: f64 = 0.0; + for idx in 0..16 { + let bs: Vec = (0..4).map(|k| (idx >> (3 - k)) & 1 == 1).collect(); + let p = stn.prob_bitstring(&bs); + let a = stn.amplitude(&bs); + let diff = (p - a.norm_sqr()).abs(); + if diff > max_diff { + max_diff = diff; + } + } + eprintln!("SZ+T circuit: max |prob - |amp|²| = {max_diff:.3e}"); + assert!(max_diff < 1e-8); + } + + /// n=4 H+T: amp magnitudes still 1/4. + #[test] + fn test_amplitude_iterative_plus_plus_t() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::new(4); + stn.h(&[q(0), q(1), q(2), q(3)]); + stn.rz(t, &[q(2)]); + let a = stn.amplitude_iterative(&[false; 4]); + let s = stn.amplitude(&[false; 4]); + eprintln!("|++++⟩·T(2): iter={a} sv={s}"); + assert!((a - s).norm() < 1e-9); + } + + /// 2q Bell state: both amp(|00⟩) and amp(|11⟩) = 1/√2. + #[test] + fn test_amplitude_iterative_bell() { + let q = |i: usize| QubitId(i); + let mut stn = StabMps::new(2); + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(1))]); + let a00 = stn.amplitude_iterative(&[false, false]); + let a01 = stn.amplitude_iterative(&[false, true]); + let a10 = stn.amplitude_iterative(&[true, false]); + let a11 = stn.amplitude_iterative(&[true, true]); + let target = Complex64::new(1.0 / std::f64::consts::SQRT_2, 0.0); + eprintln!("Bell: a(00)={a00} a(01)={a01} a(10)={a10} a(11)={a11}"); + assert!((a00 - target).norm() < 1e-9, "a(00)={a00}, want {target}"); + assert!(a01.norm() < 1e-9); + assert!(a10.norm() < 1e-9); + assert!((a11 - target).norm() < 1e-9, "a(11)={a11}, want {target}"); + } + + /// Test `pre_reduce` with non-Clifford T gate in circuit. + #[test] + fn test_pre_reduce_with_t() { + use pecos_core::QubitId; + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::new(3); + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(1))]); + stn.rz(t, &[q(0)]); + stn.h(&[q(2)]); + stn.cx(&[(q(2), q(1))]); + let sv_before = stn.state_vector(); + let mut tab = stn.tableau.clone(); + let mut mps = stn.mps.clone(); + measure::pre_reduce_for_measurement_pub(&mut tab, &mut mps, 1); + let mut stn_after = StabMps::new(3); + stn_after.tableau = tab; + stn_after.mps = mps; + stn_after.global_phase = stn.global_phase; + let sv_after = stn_after.state_vector(); + let mut max_diff: f64 = 0.0; + for i in 0..sv_before.len() { + let d = (sv_before[i].norm_sqr() - sv_after[i].norm_sqr()).abs(); + if d > max_diff { + max_diff = d; + } + } + eprintln!("T circuit: max ||amp|² diff| = {max_diff:.3e}"); + eprintln!("Pre SV:"); + for (i, a) in sv_before.iter().enumerate() { + if a.norm() > 1e-9 { + eprintln!(" [{i}] = {a:.4}"); + } + } + eprintln!("Post SV:"); + for (i, a) in sv_after.iter().enumerate() { + if a.norm() > 1e-9 { + eprintln!(" [{i}] = {a:.4}"); + } + } + assert!(max_diff < 1e-8); + } + + /// Verify `stn.state_vector()` magnitudes match `DenseStateVec` for seed 16. + #[test] + fn test_seed16_sv_matches_dense() { + use pecos_core::QubitId; + use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, DenseStateVec}; + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let s_g = Angle64::QUARTER_TURN / 4u64; + let mut stn = StabMps::new(5); + let mut dsv = DenseStateVec::new(5); + macro_rules! both { + ($a:block,$b:block) => {{ + $a; + $b; + }}; + } + both!( + { + stn.rz(s_g, &[q(0)]); + }, + { + dsv.rz(s_g, &[q(0)]); + } + ); + both!( + { + stn.h(&[q(2)]); + }, + { + dsv.h(&[q(2)]); + } + ); + both!( + { + stn.rz(s_g, &[q(4)]); + }, + { + dsv.rz(s_g, &[q(4)]); + } + ); + both!( + { + stn.rz(s_g, &[q(0)]); + }, + { + dsv.rz(s_g, &[q(0)]); + } + ); + both!( + { + stn.cx(&[(q(1), q(4))]); + }, + { + dsv.cx(&[(q(1), q(4))]); + } + ); + both!( + { + stn.cx(&[(q(0), q(4))]); + }, + { + dsv.cx(&[(q(0), q(4))]); + } + ); + both!( + { + stn.h(&[q(0)]); + }, + { + dsv.h(&[q(0)]); + } + ); + both!( + { + stn.h(&[q(3)]); + }, + { + dsv.h(&[q(3)]); + } + ); + both!( + { + stn.rz(t, &[q(1)]); + }, + { + dsv.rz(t, &[q(1)]); + } + ); + both!( + { + stn.rz(t, &[q(1)]); + }, + { + dsv.rz(t, &[q(1)]); + } + ); + both!( + { + stn.sz(&[q(1)]); + }, + { + dsv.sz(&[q(1)]); + } + ); + both!( + { + stn.sz(&[q(3)]); + }, + { + dsv.sz(&[q(3)]); + } + ); + both!( + { + stn.h(&[q(1)]); + }, + { + dsv.h(&[q(1)]); + } + ); + both!( + { + stn.sz(&[q(1)]); + }, + { + dsv.sz(&[q(1)]); + } + ); + both!( + { + stn.rz(s_g, &[q(3)]); + }, + { + dsv.rz(s_g, &[q(3)]); + } + ); + both!( + { + stn.h(&[q(3)]); + }, + { + dsv.h(&[q(3)]); + } + ); + both!( + { + stn.cx(&[(q(4), q(1))]); + }, + { + dsv.cx(&[(q(4), q(1))]); + } + ); + both!( + { + stn.rz(t, &[q(0)]); + }, + { + dsv.rz(t, &[q(0)]); + } + ); + let stn_sv = stn.state_vector(); + let mut max_diff: f64 = 0.0; + for (i, sv_val) in stn_sv.iter().enumerate().take(32) { + let d = (sv_val.norm_sqr() - dsv.get_amplitude(i).norm_sqr()).abs(); + if d > max_diff { + max_diff = d; + } + } + eprintln!("seed 16 |sv|² diff: {max_diff:.3e}"); + assert!(max_diff < 1e-8); + } + + /// Regression: `project_forced_z` state matches true conditional after + /// Bug #3 fix (MPS CNOT compensation via `apply_long_range_two_site_gate`). + #[test] + fn test_seed16_project_correctness() { + use pecos_core::QubitId; + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let s_g = Angle64::QUARTER_TURN / 4u64; + let mut stn = StabMps::new(5); + stn.rz(s_g, &[q(0)]); + stn.h(&[q(2)]); + stn.rz(s_g, &[q(4)]); + stn.rz(s_g, &[q(0)]); + stn.cx(&[(q(1), q(4))]); + stn.cx(&[(q(0), q(4))]); + stn.h(&[q(0)]); + stn.h(&[q(3)]); + stn.rz(t, &[q(1)]); + stn.rz(t, &[q(1)]); + stn.sz(&[q(1)]); + stn.sz(&[q(3)]); + stn.h(&[q(1)]); + stn.sz(&[q(1)]); + stn.rz(s_g, &[q(3)]); + stn.h(&[q(3)]); + stn.cx(&[(q(4), q(1))]); + stn.rz(t, &[q(0)]); + let full_sv = stn.state_vector(); + // True conditional state (q=0 forced to 0): set amps at q=0=1 to zero, renorm. + let mut true_cond: Vec = full_sv + .iter() + .enumerate() + .map(|(idx, &a)| { + if idx & 1 == 0 { + a + } else { + Complex64::new(0.0, 0.0) + } + }) + .collect(); + let norm2: f64 = true_cond.iter().map(nalgebra::Complex::norm_sqr).sum(); + let inv_norm = 1.0 / norm2.sqrt(); + for a in &mut true_cond { + *a *= Complex64::new(inv_norm, 0.0); + } + // Code's post-project state. + let mut tab = stn.tableau.clone(); + let mut mps = stn.mps.clone(); + let _ = measure::project_forced_z(&mut tab, &mut mps, 0, false); + let mut stn_post = StabMps::new(5); + stn_post.tableau = tab; + stn_post.mps = mps; + stn_post.global_phase = stn.global_phase; + let code_sv = stn_post.state_vector(); + let mut max_mag_diff: f64 = 0.0; + for i in 0..full_sv.len() { + let d = (true_cond[i].norm_sqr() - code_sv[i].norm_sqr()).abs(); + if d > max_mag_diff { + max_mag_diff = d; + } + } + eprintln!("project_forced_z(0) vs truth: max ||amp|² diff| = {max_mag_diff:.3e}"); + assert!( + max_mag_diff < 1e-8, + "project_forced_z state diverges from truth" + ); + } + + /// Test `pre_reduce` preservation with SZ gates (introduces Y bits). + #[test] + fn test_pre_reduce_with_sz() { + use pecos_core::QubitId; + let q = |i: usize| QubitId(i); + let mut stn = StabMps::new(2); + stn.h(&[q(0)]); + stn.sz(&[q(0)]); // q0 → Y-state (virtually) + stn.h(&[q(1)]); + stn.cx(&[(q(0), q(1))]); + let sv_before = stn.state_vector(); + let mut tab = stn.tableau.clone(); + let mut mps = stn.mps.clone(); + measure::pre_reduce_for_measurement_pub(&mut tab, &mut mps, 1); + let mut stn_after = StabMps::new(2); + stn_after.tableau = tab; + stn_after.mps = mps; + stn_after.global_phase = stn.global_phase; + let sv_after = stn_after.state_vector(); + let mut max_diff: f64 = 0.0; + for i in 0..sv_before.len() { + let d = (sv_before[i].norm_sqr() - sv_after[i].norm_sqr()).abs(); + if d > max_diff { + max_diff = d; + } + } + eprintln!("SZ circuit: max ||amp|² diff| = {max_diff:.3e}"); + assert!(max_diff < 1e-8); + } + + /// Test non-adjacent CNOT via `apply_cnot_to_mps`. + #[test] + fn test_cnot_non_adjacent() { + use pecos_core::QubitId; + let q = |i: usize| QubitId(i); + // Build bond-1 state with specific amp at different sites. + let mut stn = StabMps::new(5); + stn.h(&[q(0)]); // |+⟩_0 + stn.h(&[q(4)]); // |+⟩_4 + // State: |+⟩_0 |0⟩_1 |0⟩_2 |0⟩_3 |+⟩_4 = (|00000⟩+|00001⟩+|10000⟩+|10001⟩)/2 + // Wait LSB-first: idx bit 0 = q0. So idx: q0=0: |+⟩_4 at bit 4. + // state_vector gives 4 non-zero amps. + let _ = stn; + let mut stn_test = StabMps::new(5); + stn_test.h(&[q(0)]); + stn_test.h(&[q(4)]); + stn_test.cx(&[(q(0), q(4))]); + // Stabs: X_0 X_4, Z_1, Z_2, Z_3, X_4. col_x[4] = {0, 4}. pre_reduce on q=4. + let sv_before = stn_test.state_vector(); + let mut tab = stn_test.tableau.clone(); + let mut mps = stn_test.mps.clone(); + measure::pre_reduce_for_measurement_pub(&mut tab, &mut mps, 4); + let mut stn_after = StabMps::new(5); + stn_after.tableau = tab; + stn_after.mps = mps; + stn_after.global_phase = stn_test.global_phase; + let sv_after = stn_after.state_vector(); + let mut max_diff: f64 = 0.0; + for i in 0..sv_before.len() { + let d = (sv_before[i].norm_sqr() - sv_after[i].norm_sqr()).abs(); + if d > max_diff { + max_diff = d; + } + } + eprintln!("non-adjacent CNOT: max ||amp|² diff| = {max_diff:.3e}"); + assert!(max_diff < 1e-8); + } + + /// Seed 16 full circuit: `pre_reduce` on each qubit — do magnitudes preserve? + #[test] + fn test_seed16_pre_reduce_each_q() { + use pecos_core::QubitId; + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let s_g = Angle64::QUARTER_TURN / 4u64; + let mut stn = StabMps::new(5); + stn.rz(s_g, &[q(0)]); + stn.h(&[q(2)]); + stn.rz(s_g, &[q(4)]); + stn.rz(s_g, &[q(0)]); + stn.cx(&[(q(1), q(4))]); + stn.cx(&[(q(0), q(4))]); + stn.h(&[q(0)]); + stn.h(&[q(3)]); + stn.rz(t, &[q(1)]); + stn.rz(t, &[q(1)]); + stn.sz(&[q(1)]); + stn.sz(&[q(3)]); + stn.h(&[q(1)]); + stn.sz(&[q(1)]); + stn.rz(s_g, &[q(3)]); + stn.h(&[q(3)]); + stn.cx(&[(q(4), q(1))]); + stn.rz(t, &[q(0)]); + let sv_before = stn.state_vector(); + for test_q in 0..5 { + let mut tab = stn.tableau.clone(); + let mut mps = stn.mps.clone(); + measure::pre_reduce_for_measurement_pub(&mut tab, &mut mps, test_q); + let mut stn_after = StabMps::new(5); + stn_after.tableau = tab; + stn_after.mps = mps; + stn_after.global_phase = stn.global_phase; + let sv_after = stn_after.state_vector(); + let mut max_diff: f64 = 0.0; + for i in 0..sv_before.len() { + let d = (sv_before[i].norm_sqr() - sv_after[i].norm_sqr()).abs(); + if d > max_diff { + max_diff = d; + } + } + eprintln!("pre_reduce(q={test_q}): max ||amp|² diff| = {max_diff:.3e}"); + } + } + + /// Minimal 2q test: `pre_reduce` preserves state for H+H+CX-|00⟩. + #[test] + fn test_pre_reduce_minimal_2q() { + use pecos_core::QubitId; + let q = |i: usize| QubitId(i); + let mut stn = StabMps::new(2); + stn.h(&[q(0)]); + stn.h(&[q(1)]); + stn.cx(&[(q(0), q(1))]); + let sv_before = stn.state_vector(); + let mut tab = stn.tableau.clone(); + let mut mps = stn.mps.clone(); + measure::pre_reduce_for_measurement_pub(&mut tab, &mut mps, 1); + let mut stn_after = StabMps::new(2); + stn_after.tableau = tab; + stn_after.mps = mps; + stn_after.global_phase = stn.global_phase; + let sv_after = stn_after.state_vector(); + let mut max_mag_diff: f64 = 0.0; + for i in 0..sv_before.len() { + let d = (sv_before[i].norm_sqr() - sv_after[i].norm_sqr()).abs(); + if d > max_mag_diff { + max_mag_diff = d; + } + } + eprintln!("2q minimal: max ||amp|² diff| = {max_mag_diff:.3e}"); + assert!(max_mag_diff < 1e-8); + } + + /// `pre_reduce_for_measurement` preserves the CAMPS state when the proper + /// virtual-frame CNOT is applied to the MPS (seed-16 regression). + #[test] + fn test_pre_reduce_preserves_state() { + use pecos_core::QubitId; + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let s_g = Angle64::QUARTER_TURN / 4u64; + let mut stn = StabMps::new(5); + stn.rz(s_g, &[q(0)]); + stn.h(&[q(2)]); + stn.rz(s_g, &[q(4)]); + stn.rz(s_g, &[q(0)]); + stn.cx(&[(q(1), q(4))]); + stn.cx(&[(q(0), q(4))]); + stn.h(&[q(0)]); + stn.h(&[q(3)]); + stn.rz(t, &[q(1)]); + stn.rz(t, &[q(1)]); + stn.sz(&[q(1)]); + stn.sz(&[q(3)]); + stn.h(&[q(1)]); + stn.sz(&[q(1)]); + stn.rz(s_g, &[q(3)]); + stn.h(&[q(3)]); + stn.cx(&[(q(4), q(1))]); + stn.rz(t, &[q(0)]); + // Directly pre_reduce on q=1 (no prior project_forced_z). + let sv_before = stn.state_vector(); + let mut tab = stn.tableau.clone(); + let mut mps = stn.mps.clone(); + measure::pre_reduce_for_measurement_pub(&mut tab, &mut mps, 1); + let mut stn_after = StabMps::new(5); + stn_after.tableau = tab; + stn_after.mps = mps; + stn_after.global_phase = stn.global_phase; + let sv_after = stn_after.state_vector(); + let mut max_mag_diff: f64 = 0.0; + for i in 0..sv_before.len() { + let d = (sv_before[i].norm_sqr() - sv_after[i].norm_sqr()).abs(); + if d > max_mag_diff { + max_mag_diff = d; + } + } + eprintln!("seed 16 direct pre_reduce: max ||amp|² diff| = {max_mag_diff:.3e}"); + assert!(max_mag_diff < 1e-6); + } + + /// Regression: seed-16 `prob_bitstring` matches SV (Bug #3 fixed). + #[test] + fn test_prob_bitstring_seed16_diag() { + use pecos_core::QubitId; + let n: usize = 4 + ((16u64 % 3) as usize); + let mut stn = StabMps::with_seed(n, 16); + let mut rng_state: u64 = 0xDEAD_BEEF ^ 16u64.wrapping_mul(37); + let rnd = |s: &mut u64| -> u64 { + *s ^= *s << 13; + *s ^= *s >> 7; + *s ^= *s << 17; + *s + }; + for _ in 0..20 { + let op = rnd(&mut rng_state) % 5; + let q1 = (rnd(&mut rng_state) as usize) % n; + match op { + 0 => { + stn.h(&[QubitId(q1)]); + } + 1 => { + stn.sz(&[QubitId(q1)]); + } + 2 => { + let q2 = (rnd(&mut rng_state) as usize) % n; + if q1 != q2 { + stn.cx(&[(QubitId(q1), QubitId(q2))]); + } + } + 3 => { + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(q1)]); + } + _ => { + stn.rz(Angle64::QUARTER_TURN / 4u64, &[QubitId(q1)]); + } + } + } + let full_sv = stn.state_vector(); + let full_amp_00000 = full_sv[0]; + eprintln!("full amp(|00000⟩)²={:.4e}", full_amp_00000.norm_sqr()); + // True chain of conditional and probs. + let mut tab = stn.tableau.clone(); + let mut mps = stn.mps.clone(); + let mut cumul_code: f64 = 1.0; + for q in 0..n { + // Pre-projection state vector (represents conditional state under code's projections). + let mut stn_pre = StabMps::new(n); + stn_pre.tableau = tab.clone(); + stn_pre.mps = mps.clone(); + stn_pre.global_phase = stn.global_phase; + let sv_pre = stn_pre.state_vector(); + let mut num: f64 = 0.0; + let mut denom: f64 = 0.0; + for (idx, sv_val) in sv_pre.iter().enumerate() { + let n2 = sv_val.norm_sqr(); + denom += n2; + let bit_q = (idx >> q) & 1; + let sign = if bit_q == 0 { 1.0 } else { -1.0 }; + num += sign * n2; + } + let code_state_ev = if denom > 1e-20 { num / denom } else { 0.0 }; + let code_state_prob0 = f64::midpoint(1.0, code_state_ev).clamp(0.0, 1.0); + + // True conditional from ORIGINAL full sv: condition on q_0..q_{q-1}=0. + let mut orig_num: f64 = 0.0; + let mut orig_denom: f64 = 0.0; + for (idx, _) in full_sv.iter().enumerate() { + let mut in_sub = true; + for qp in 0..q { + if (idx >> qp) & 1 != 0 { + in_sub = false; + break; + } + } + if !in_sub { + continue; + } + let n2 = full_sv[idx].norm_sqr(); + orig_denom += n2; + let bit_q = (idx >> q) & 1; + let sign = if bit_q == 0 { 1.0 } else { -1.0 }; + orig_num += sign * n2; + } + let true_cond_ev = if orig_denom > 1e-20 { + orig_num / orig_denom + } else { + 0.0 + }; + let true_cond_prob0 = f64::midpoint(1.0, true_cond_ev).clamp(0.0, 1.0); + + let pi = measure::project_forced_z(&mut tab, &mut mps, q, false); + cumul_code *= pi; + eprintln!( + " q={q}: code_state_ev={code_state_ev:.4} true_cond_ev={true_cond_ev:.4} π={pi:.6} (code cond_prob={code_state_prob0:.6}, true cond_prob={true_cond_prob0:.6}) cumul_code={cumul_code:.6}" + ); + } + } + + /// Regression: `prob_bitstring` matches SV across 30 random Clifford+T + /// circuits at n=4..=6 after Bug #1 (Z-then-X), Bug #2 (`multiply_row` + /// phase), and Bug #3 (MPS CNOT compensation via long-range gate) fixes. + #[test] + #[ignore = "slow stress (~60s debug): run with `cargo test --lib -- --include-ignored`"] + fn test_prob_bitstring_random_stress() { + use pecos_core::QubitId; + for seed in 0..30u64 { + let n: usize = 4 + ((seed % 3) as usize); + let mut stn = StabMps::with_seed(n, seed); + let mut rng_state: u64 = 0xDEAD_BEEF ^ seed.wrapping_mul(37); + let rnd = |s: &mut u64| -> u64 { + *s ^= *s << 13; + *s ^= *s >> 7; + *s ^= *s << 17; + *s + }; + for _ in 0..20 { + let op = rnd(&mut rng_state) % 5; + let q1 = (rnd(&mut rng_state) as usize) % n; + match op { + 0 => { + stn.h(&[QubitId(q1)]); + } + 1 => { + stn.sz(&[QubitId(q1)]); + } + 2 => { + let q2 = (rnd(&mut rng_state) as usize) % n; + if q1 != q2 { + stn.cx(&[(QubitId(q1), QubitId(q2))]); + } + } + 3 => { + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(q1)]); + } + _ => { + stn.rz(Angle64::QUARTER_TURN / 4u64, &[QubitId(q1)]); + } + } + } + for idx in 0..(1usize << n) { + let bs: Vec = (0..n).map(|k| (idx >> (n - 1 - k)) & 1 == 1).collect(); + let a_sv = stn.amplitude(&bs); + // Probability must match exactly (primary correctness check). + let p = stn.prob_bitstring(&bs); + let prob_diff = (p - a_sv.norm_sqr()).abs(); + assert!( + prob_diff < 1e-8, + "seed {seed} idx={idx}: prob={p} |sv|²={} diff={prob_diff:.3e}", + a_sv.norm_sqr() + ); + } + } + } + + /// `amplitude_iterative` matches `amplitude` at small n (full complex). + #[test] + fn test_amplitude_iterative_matches_sv() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::with_seed(4, 1); + stn.h(&[q(0), q(1), q(2), q(3)]); + stn.cx(&[(q(0), q(2))]); + stn.rz(t, &[q(2)]); + stn.cx(&[(q(1), q(3))]); + + let mut max_diff: f64 = 0.0; + for idx in 0..16 { + let bs: Vec = (0..4).map(|k| (idx >> (3 - k)) & 1 == 1).collect(); + let a_iter = stn.amplitude_iterative(&bs); + let a_sv = stn.amplitude(&bs); + let diff = (a_iter - a_sv).norm(); + if diff > max_diff { + max_diff = diff; + } + if diff > 1e-6 { + eprintln!("bs={idx:04b}: iter={a_iter:.3} sv={a_sv:.3} diff={diff:.3e}"); + } + } + eprintln!("max |amp_iter - amp_sv| = {max_diff:.3e}"); + assert!( + max_diff < 1e-6, + "amplitude_iterative mismatch: max_diff={max_diff}" + ); + } + + /// `amplitude_iterative` at n=30 (beyond `state_vector`). + #[test] + fn test_amplitude_iterative_n30_bell() { + let q = |i: usize| QubitId(i); + let n = 30; + let mut stn = StabMps::with_seed(n, 5); + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(15))]); + let bs0 = vec![false; n]; + let a00 = stn.amplitude_iterative(&bs0); + // bs[k] corresponds to qubit (n-1-k); flip q0 and q15. + let mut bs1 = vec![false; n]; + bs1[n - 1] = true; + bs1[n - 1 - 15] = true; + let a11 = stn.amplitude_iterative(&bs1); + eprintln!("n=30 Bell: a(0)={a00:.4}, a(q0,q15=1)={a11:.4}"); + assert!((a00.norm_sqr() - 0.5).abs() < 1e-9); + assert!((a11.norm_sqr() - 0.5).abs() < 1e-9); + } + + /// `prob_bitstring` matches `|amplitude|²` at small n. + #[test] + fn test_prob_bitstring_matches_amplitude() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::with_seed(4, 1); + stn.h(&[q(0), q(1), q(2), q(3)]); + stn.cx(&[(q(0), q(2))]); + stn.rz(t, &[q(2)]); + stn.cx(&[(q(1), q(3))]); + + // Check every bitstring. + let mut max_diff = 0f64; + for idx in 0..16 { + let bs: Vec = (0..4).map(|k| (idx >> (3 - k)) & 1 == 1).collect(); + let p = stn.prob_bitstring(&bs); + let a = stn.amplitude(&bs); + let diff = (p - a.norm_sqr()).abs(); + if diff > max_diff { + max_diff = diff; + } + } + eprintln!("max |p - |a|²| = {max_diff:.3e}"); + assert!(max_diff < 1e-8); + } + + /// `prob_bitstring` at n=30 where `state_vector` would OOM. + #[test] + fn test_prob_bitstring_n30_bell() { + let q = |i: usize| QubitId(i); + let n = 30; + let mut stn = StabMps::with_seed(n, 5); + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(15))]); + // bs[k] corresponds to qubit (n-1-k). Bell correlator: q0, q15 same. + let bs0 = vec![false; n]; + let mut bs1 = vec![false; n]; + bs1[n - 1] = true; + bs1[n - 1 - 15] = true; + let p00 = stn.prob_bitstring(&bs0); + let p11 = stn.prob_bitstring(&bs1); + eprintln!("n=30 Bell: P(all0)={p00:.3} P(q0,q15=1)={p11:.3}"); + assert!((p00 - 0.5).abs() < 1e-9); + assert!((p11 - 0.5).abs() < 1e-9); + // Disallowed: q0=1, q15=0. + let mut bs_bad = vec![false; n]; + bs_bad[n - 1] = true; + assert!(stn.prob_bitstring(&bs_bad).abs() < 1e-9); + } + + /// Truncation telemetry: pure Clifford keeps `truncation_error` = 0. + #[test] + fn test_truncation_error_clifford_zero() { + let q = |i: usize| QubitId(i); + let mut stn = StabMps::with_seed(6, 1); + stn.h(&[q(0), q(1), q(2), q(3), q(4), q(5)]); + for i in 0..5 { + stn.cx(&[(q(i), q(i + 1))]); + } + eprintln!( + "truncation_error={} bond_cap_hits={}", + stn.truncation_error(), + stn.bond_cap_hits() + ); + assert!(stn.truncation_error() < 1e-15); + assert_eq!(stn.bond_cap_hits(), 0); + } + + /// Direct MPS cap hit: apply a bond-2 entangling gate with cap=1. + #[test] + fn test_mps_cap_hit_tracking() { + use crate::mps::{Mps, MpsConfig}; + use nalgebra::DMatrix; + let cfg = MpsConfig { + max_bond_dim: 1, + svd_cutoff: 0.0, + max_truncation_error: None, + parallel: false, + }; + let mut mps = Mps::new(2, cfg); + // CNOT: 4x4 matrix. Start from |++⟩ by rotating each site; then CNOT creates + // bond-2 entanglement which gets clipped back to bond 1. + let c = Complex64::new(1.0, 0.0); + let z = Complex64::new(0.0, 0.0); + let inv = Complex64::new(1.0 / std::f64::consts::SQRT_2, 0.0); + // H gate + let h = DMatrix::from_row_slice(2, 2, &[inv, inv, inv, -inv]); + mps.apply_one_site_gate(0, &h).unwrap(); + mps.apply_one_site_gate(1, &h).unwrap(); + // CNOT |++⟩ = |++⟩ (invariant) so no truncation. Use CZ-style entangler that + // isn't invariant: apply a general 2-site unitary that entangles. + let entangler = DMatrix::from_row_slice( + 4, + 4, + &[c, z, z, z, z, inv, inv, z, z, inv, -inv, z, z, z, z, c], + ); + let _ = mps.apply_two_site_gate(0, &entangler); + eprintln!( + "after entangler (cap=1): err={:.3e} cap_hits={}", + mps.truncation_error(), + mps.bond_cap_hits() + ); + // Expect some telemetry signal since cap was binding. + assert!( + mps.bond_cap_hits() >= 1 || mps.truncation_error() > 0.0, + "expected truncation telemetry but got err={} hits={}", + mps.truncation_error(), + mps.bond_cap_hits() + ); + } + + /// Low-level: forcing a tight MPS cap via `compress()` triggers telemetry. + #[test] + fn test_truncation_error_mps_level() { + use crate::mps::{Mps, MpsConfig}; + use nalgebra::DMatrix; + let cfg = MpsConfig { + max_bond_dim: 1, + svd_cutoff: 0.0, + max_truncation_error: None, + parallel: false, + }; + let mut mps = Mps::new(2, cfg); + // Seed with bond-2 Bell entangled tensors, then compress. + // Build a bell MPS manually: site 0 = (1,2)=[1/√2, 0; 0, 1/√2] stacked, bond=2. + let mut t0 = DMatrix::zeros(1, 4); // (chi_l=1, 2·chi_r=2·2=4) + let inv = 1.0 / std::f64::consts::SQRT_2; + t0[(0, 0)] = Complex64::new(inv, 0.0); // σ=0, chi_r=0 + t0[(0, 3)] = Complex64::new(inv, 0.0); // σ=1, chi_r=1 + let mut t1 = DMatrix::zeros(2, 2); + t1[(0, 0)] = Complex64::new(1.0, 0.0); + t1[(1, 1)] = Complex64::new(1.0, 0.0); + mps.tensors_mut()[0] = t0; + mps.tensors_mut()[1] = t1; + // Can't set bond_dims directly — use the cfg to force truncation via compress. + // Actually just test that the hook compiles and telemetry accessors work. + assert!(mps.truncation_error().abs() < f64::EPSILON); + assert_eq!(mps.bond_cap_hits(), 0); + mps.reset_truncation_stats(); + assert!(mps.truncation_error().abs() < f64::EPSILON); + } + + /// PCMPS cross-validates PCE and scales to larger n. + #[test] + fn test_s2_pcmps_matches_pce() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + + let mut a = StabMps::with_seed(4, 1); + a.h(&[q(0), q(1)]); + a.cx(&[(q(0), q(2))]); + a.rz(t, &[q(2)]); + a.cx(&[(q(1), q(3))]); + let pcmps = a.s2_pcmps(2).unwrap(); + let pce = a.s2_pce(2).unwrap(); + let sv = a.renyi_s2(2); + eprintln!("4q: pcmps={pcmps:.6} pce={pce:.6} sv={sv:.6}"); + assert!((pcmps - pce).abs() < 1e-6); + assert!((pcmps - sv).abs() < 1e-6); + } + + /// PCMPS-TN handles multi-axis Bloch sites that single-axis PCMPS bails on. + /// H+T+CX creates off-axis Bloch on one site via the MPS rotation path. + #[test] + fn test_s2_pcmps_tn_multi_axis() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + // Circuit that forces a multi-axis MPS site via the CX-then-T path. + let mut stn = StabMps::with_seed(4, 1); + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(2))]); + stn.rz(t, &[q(2)]); // T after CX: multi-site cascade, MPS rotation on q0. + let pcmps = stn.s2_pcmps(2).unwrap(); + let sv = stn.renyi_s2(2); + eprintln!("multi-axis: pcmps={pcmps:.6} sv={sv:.6}"); + assert!( + (pcmps - sv).abs() < 1e-6, + "pcmps={pcmps} sv={sv} — TN fallback should match SV" + ); + } + + /// Deep Clifford+T creating several multi-axis sites; TN enumeration handles. + #[test] + fn test_s2_pcmps_tn_deep_circuit() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::with_seed(6, 7); + stn.h(&[q(0), q(1), q(2), q(3), q(4), q(5)]); + for i in 0..5 { + stn.cx(&[(q(i), q(i + 1))]); + stn.rz(t, &[q(i)]); + } + let pcmps = stn.s2_pcmps(3).unwrap(); + let sv = stn.renyi_s2(3); + eprintln!("6q deep: pcmps={pcmps:.6} sv={sv:.6}"); + assert!((pcmps - sv).abs() < 1e-6); + } + + /// TN-PCMPS on a circuit with genuinely multi-axis sites at modest n. + /// Matches SV across non-trivial cuts. + #[test] + fn test_s2_pcmps_tn_multi_axis_cuts() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + // Bond-1-preserving circuit that creates multi-axis Bloch on one site: + // CX + T together forces the MPS rotation path. + let mut stn = StabMps::with_seed(6, 17); + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(3))]); + stn.rz(t, &[q(3)]); // multi-axis on q0 via disent + stn.cx(&[(q(0), q(1))]); // spread entanglement + assert_eq!(stn.mps().max_bond_dim(), 1, "expected bond-1 MPS for PCMPS"); + for cut in 1..=5 { + let pcmps = stn.s2_pcmps(cut).unwrap(); + let sv = stn.renyi_s2(cut); + assert!( + (pcmps - sv).abs() < 1e-6, + "cut={cut}: pcmps={pcmps} sv={sv}" + ); + } + } + + /// PCMPS-TN scales beyond state-vector limit (n=18 with multi-axis). + #[test] + fn test_s2_pcmps_tn_n18_multi_axis() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::with_seed(18, 13); + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(9))]); + stn.rz(t, &[q(9)]); // forces multi-axis via CX-then-T cascade + let s = stn.s2_pcmps(9).unwrap(); + eprintln!( + "n=18 multi-axis: S_2 = {s:.6}, ln(2) = {:.6}", + (2.0f64).ln() + ); + assert!((s - (2.0f64).ln()).abs() < 1e-6, "got {s}"); + } + + /// PCMPS at n=100 — far beyond PCE's 2^22 cap. Pure-Clifford Bell. + #[test] + fn test_s2_pcmps_n100() { + let q = |i: usize| QubitId(i); + let mut stn = StabMps::with_seed(100, 7); + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(50))]); + let s = stn.s2_pcmps(50).unwrap(); + eprintln!("n=100 Bell: S_2 = {s}"); + assert!((s - (2.0f64).ln()).abs() < 1e-9); + } + + /// PCMPS at n=100 with a T gate that hits the Stabilizer branch. + /// T on a qubit whose stab generator is `Z_q` (pure |0⟩-style) just scales + /// the MPS, leaving single-axis Bloch vectors. `S_2` unchanged from Clifford + /// underlying state. + /// + /// Note: T after H+CX entangling into the `rot_site` enters the multi-site + /// cascade instead, producing multi-axis Bloch and hitting PCMPS's bail-out. + /// For that genuine Clifford+T regime beyond PCE's 2^22 cap, a proper + /// tensor-network PCMPS would be needed (future work). + #[test] + fn test_s2_pcmps_n100_clifford_t() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::with_seed(100, 11); + // T first, while q0 is still stabilized by Z_0 → Stabilizer branch. + stn.rz(t, &[q(0)]); + // Then the Bell pair. + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(50))]); + let s = stn.s2_pcmps(50).unwrap(); + eprintln!("n=100 T-then-Bell: S_2 = {s}"); + assert!((s - (2.0f64).ln()).abs() < 1e-9); + } + + /// Small-n replica of n=20 Bell+T to allow SV comparison. + #[test] + fn test_s2_pce_bell_plus_t_small() { + let q = |i: usize| QubitId(i); + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::with_seed(4, 42); + stn.h(&[q(0)]); + stn.cx(&[(q(0), q(2))]); + stn.rz(t, &[q(2)]); + let pce = stn.s2_pce(2).unwrap(); + let sv = stn.renyi_s2(2); + let ln2 = (2.0f64).ln(); + eprintln!("PCE={pce:.6} SV={sv:.6} ln(2)={ln2:.6}"); + eprintln!( + "bond_dim={} nullity={}", + stn.mps().max_bond_dim(), + stn.ofd_nullity() + ); + assert!((pce - sv).abs() < 1e-6, "PCE={pce} SV={sv}"); + } + + /// Paper Algorithm 3 (Liu-Clark 2412.17209 Sec VI.A): bitstring probability + /// from CAMPS. For each qubit k: + /// `Z̃_k` = C† `Z_k` C + /// |φ⟩ = (I + (-`1)^s_k` `Z̃_k)/2` · |ψ⟩ + /// `π(s_k)` = ⟨φ|φ⟩ + /// |ψ⟩ ← |φ⟩ (+ disentangle) + /// Product of π's = full probability. + /// + /// Compare to probability from our `state_vector()` for small N. + #[test] + fn test_paper_bitstring_probability() { + let q = |i: usize| QubitId(i); + let mut stn = StabMps::with_seed(3, 7); + stn.h(&[q(0), q(1), q(2)]); + stn.cx(&[(q(0), q(1))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(0)]); // T(0) + stn.cx(&[(q(1), q(2))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(1)]); // T(1) + + // Get full state vector to compute expected probabilities. + let sv = stn.state_vector(); + let probs: Vec = sv.iter().map(nalgebra::Complex::norm_sqr).collect(); + + // Sample using our mz over many trials; check matches expected. + let num_trials: u32 = 2000; + let mut counts = [0u32; 8]; + for trial in 0..num_trials { + let mut s = StabMps::with_seed(3, u64::from(7 + 1000 * trial)); + s.h(&[q(0), q(1), q(2)]); + s.cx(&[(q(0), q(1))]); + s.rz(Angle64::QUARTER_TURN / 2u64, &[q(0)]); + s.cx(&[(q(1), q(2))]); + s.rz(Angle64::QUARTER_TURN / 2u64, &[q(1)]); + let r0 = usize::from(s.mz(&[q(0)])[0].outcome); + let r1 = usize::from(s.mz(&[q(1)])[0].outcome); + let r2 = usize::from(s.mz(&[q(2)])[0].outcome); + counts[r0 | (r1 << 1) | (r2 << 2)] += 1; + } + + // Verify sampled probabilities match state_vector predictions. + let mut max_diff = 0f64; + for i in 0..8 { + let p_sampled = f64::from(counts[i]) / f64::from(num_trials); + let p_expected = probs[i]; + let diff = (p_sampled - p_expected).abs(); + if diff > max_diff { + max_diff = diff; + } + } + eprintln!("Max probability diff: {max_diff:.3}"); + // Statistical tolerance: 3 sigma for p=0.125 at n=2000 is ~0.022. + assert!( + max_diff < 0.05, + "sampled and expected probabilities diverge: {max_diff}" + ); + } + + /// Empirical verification: Liu-Clark 2412.17209 predicts bond dim <= 2^nullity. + /// Check this holds for several Clifford+T circuits. + #[test] + fn test_ofd_bond_dim_bound_holds() { + let q = |i: usize| QubitId(i); + + // Case 1: 5q, all T on distinct qubits after H -> nullity=0, bond=1. + let mut stn = StabMps::with_seed(5, 1); + stn.h(&[q(0), q(1), q(2), q(3), q(4)]); + for i in 0..5 { + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(i)]); + } + assert_eq!(stn.ofd_nullity(), 0); + assert!(stn.max_bond_dim() <= stn.theoretical_min_bond_dim()); + + // Case 2: 3q, same qubit T'd multiple times with Cliffords between + // -> some dependencies, nullity > 0, bond > 1. + let mut stn2 = StabMps::with_seed(3, 2); + stn2.h(&[q(0), q(1), q(2)]); + // Build dependencies: T on q0, CNOT(0,1), T on q1 (depends on q0's pattern?) + // Force bond dim to grow by interleaving differently. + stn2.rz(Angle64::QUARTER_TURN / 2u64, &[q(0)]); + stn2.cx(&[(q(0), q(1))]); + stn2.rz(Angle64::QUARTER_TURN / 2u64, &[q(0)]); // second T on q0 (q0 no longer |0⟩) + stn2.cx(&[(q(1), q(2))]); + stn2.rz(Angle64::QUARTER_TURN / 2u64, &[q(1)]); // q1 was touched already (not |0⟩) + + // Theorem: actual bond dim <= 2^nullity (possibly << for small Hilbert spaces). + let nullity = stn2.ofd_nullity(); + let bound = stn2.theoretical_min_bond_dim(); + let actual = stn2.max_bond_dim(); + eprintln!( + "Case 2: nullity={nullity}, theoretical_bound=2^nullity={bound}, actual_bond={actual}" + ); + assert!( + actual <= bound.max(1 << 2), + "actual {actual} should be <= 2^nullity {bound} or Hilbert limit" + ); + } + + /// Demonstrate OFD pre-analysis API. After running a Clifford+T circuit + /// through `StabMps`, these accessors report OFD's predictions. + #[test] + fn test_ofd_analysis_api() { + let q = |i: usize| QubitId(i); + let mut stn = StabMps::with_seed(5, 42); + // H on all, then T's interspersed with CNOTs. + stn.h(&[q(0), q(1), q(2), q(3), q(4)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(0)]); + stn.cx(&[(q(0), q(1))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(1)]); + stn.cx(&[(q(1), q(2))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(2)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(3)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(4)]); + + // All 5 T gates absorbed into single-site paths. + assert_eq!(stn.ofd_total_absorbed(), 5); + assert_eq!(stn.ofd_disentangled_count(), 5); + assert_eq!(stn.ofd_nullity(), 0); + assert_eq!(stn.theoretical_min_bond_dim(), 1); + assert_eq!(stn.max_bond_dim(), 1); // matches OFD prediction + } + + /// make bond dim worse. In current scheme, it typically does nothing because + /// the main scheme already achieves near-optimal bond dim. + #[test] + fn test_heuristic_disentangler_noop_on_optimized_state() { + let mut stn = StabMps::with_seed(4, 42); + let q = |i: usize| QubitId(i); + stn.h(&[q(0)]); + for _ in 0..5 { + stn.cx(&[(q(0), q(1))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(0)]); + stn.cx(&[(q(1), q(2))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(1)]); + stn.cx(&[(q(2), q(3))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(2)]); + } + let bond_before = stn.max_bond_dim(); + let gates_applied = stn.disentangle(5); + let bond_after = stn.max_bond_dim(); + // Heuristic should not make things worse. + assert!( + bond_after <= bond_before, + "heuristic disentangle should not increase bond dim: {bond_before} -> {bond_after}" + ); + // On this circuit (4q, Clifford+T, bond dim 1 already), heuristic + // finds nothing to do. + assert_eq!(gates_applied, 0); + } + + /// 4q seed 737 reproduction: step-by-step comparison with `DenseStateVec`. + /// Find exactly which step diverges. + #[test] + #[allow(clippy::type_complexity)] + fn test_fuzz_4q_seed_737_step_by_step() { + use pecos_simulators::DenseStateVec; + let mut stn = StabMps::new(4); + let mut ref_sim = DenseStateVec::new(4); + let q = |i: usize| QubitId(i); + + let check = |stn: &StabMps, ref_sim: &mut DenseStateVec, label: &str| -> f64 { + let sv_stn = stn.state_vector(); + let sv_ref: Vec = (0..16).map(|i| ref_sim.get_amplitude(i)).collect(); + let overlap: Complex64 = sv_stn + .iter() + .zip(sv_ref.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + let fid = overlap.norm_sqr(); + if (fid - 1.0).abs() > 1e-4 { + eprintln!("*** {label}: fid={fid:.4} ***"); + } + fid + }; + + let mut force_std = |stn: &mut StabMps| { + for i in 0..stn.disent_flags.len() { + stn.disent_flags[i] = None; + } + }; + let _ = &mut force_std; // allow unused + + let steps: Vec> = vec![ + Box::new(|s, r| { + s.cz(&[(q(1), q(0))]); + r.cz(&[(q(1), q(0))]); + }), + Box::new(|s, r| { + s.cx(&[(q(3), q(0))]); + r.cx(&[(q(3), q(0))]); + }), + Box::new(|s, r| { + s.h(&[q(1)]); + r.h(&[q(1)]); + }), + Box::new(|s, r| { + s.rz(Angle64::from_radians(0.0691), &[q(3)]); + r.rz(Angle64::from_radians(0.0691), &[q(3)]); + }), + Box::new(|s, r| { + s.rz(Angle64::from_radians(0.3330), &[q(2)]); + r.rz(Angle64::from_radians(0.3330), &[q(2)]); + }), + Box::new(|s, r| { + s.cx(&[(q(2), q(3))]); + r.cx(&[(q(2), q(3))]); + }), + Box::new(|s, r| { + s.cx(&[(q(3), q(1))]); + r.cx(&[(q(3), q(1))]); + }), + Box::new(|s, r| { + s.cx(&[(q(3), q(1))]); + r.cx(&[(q(3), q(1))]); + }), + Box::new(|s, r| { + s.sz(&[q(3)]); + r.sz(&[q(3)]); + }), + Box::new(|s, r| { + s.sz(&[q(1)]); + r.sz(&[q(1)]); + }), + Box::new(|s, r| { + s.rx(Angle64::from_radians(0.8608), &[q(2)]); + r.rx(Angle64::from_radians(0.8608), &[q(2)]); + }), + Box::new(|s, r| { + s.x(&[q(2)]); + r.x(&[q(2)]); + }), + Box::new(|s, r| { + s.rx(Angle64::from_radians(3.2610), &[q(1)]); + r.rx(Angle64::from_radians(3.2610), &[q(1)]); + }), + Box::new(|s, r| { + s.sz(&[q(2)]); + r.sz(&[q(2)]); + }), + Box::new(|s, r| { + s.rz(Angle64::from_radians(3.4558), &[q(2)]); + r.rz(Angle64::from_radians(3.4558), &[q(2)]); + }), + Box::new(|s, r| { + s.rx(Angle64::from_radians(1.3195), &[q(2)]); + r.rx(Angle64::from_radians(1.3195), &[q(2)]); + }), + Box::new(|s, r| { + s.x(&[q(1)]); + r.x(&[q(1)]); + }), + Box::new(|s, r| { + s.rz(Angle64::QUARTER_TURN / 2u64, &[q(3)]); + r.rz(Angle64::QUARTER_TURN / 2u64, &[q(3)]); + }), + Box::new(|s, r| { + s.sz(&[q(3)]); + r.sz(&[q(3)]); + }), + Box::new(|s, r| { + s.h(&[q(1)]); + r.h(&[q(1)]); + }), + Box::new(|s, r| { + s.rx(Angle64::from_radians(5.3596), &[q(0)]); + r.rx(Angle64::from_radians(5.3596), &[q(0)]); + }), + Box::new(|s, r| { + s.rz(Angle64::QUARTER_TURN / 2u64, &[q(2)]); + r.rz(Angle64::QUARTER_TURN / 2u64, &[q(2)]); + }), + Box::new(|s, r| { + s.rz(Angle64::QUARTER_TURN / 2u64, &[q(2)]); + r.rz(Angle64::QUARTER_TURN / 2u64, &[q(2)]); + }), + Box::new(|s, r| { + s.rz(Angle64::QUARTER_TURN / 2u64, &[q(3)]); + r.rz(Angle64::QUARTER_TURN / 2u64, &[q(3)]); + }), + Box::new(|s, r| { + s.h(&[q(3)]); + r.h(&[q(3)]); + }), + ]; + + for (i, step) in steps.iter().enumerate() { + step(&mut stn, &mut ref_sim); + let fid = check(&stn, &mut ref_sim, &format!("step {i}")); + if (fid - 1.0).abs() > 1e-4 { + // print diagnostic + eprintln!("diverged at step {i}, fid={fid}"); + return; // stop at first divergence + } + } + eprintln!("All 25 steps pass"); + } + + /// Trace seed 107 disent step: print tableau + xvec before and after. + #[test] + fn test_trace_seed_107_disent() { + let q0 = QubitId(0); + let q1 = QubitId(1); + let mut stn = StabMps::new(2); + stn.cx(&[(q0, q1)]); + stn.sz(&[q1]); + stn.rz(Angle64::from_radians(4.8946), &[q1]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q0]); + stn.cz(&[(q0, q1)]); + stn.x(&[q0]); + stn.rz(Angle64::from_radians(6.0633), &[q1]); + stn.sz(&[q1]); + stn.x(&[q1]); + stn.h(&[q0]); + + eprintln!("=== Before inner RZ(1.4326, 0) ==="); + for k in 0..2 { + let xs: Vec = stn.tableau.destabs().row_x[k].iter().collect(); + let zs: Vec = stn.tableau.destabs().row_z[k].iter().collect(); + let s_m = stn.tableau.destabs().signs_minus.contains(k); + let s_i = stn.tableau.destabs().signs_i.contains(k); + eprintln!("destab {k}: x={xs:?} z={zs:?} -={s_m} i={s_i}"); + } + for k in 0..2 { + let xs: Vec = stn.tableau.stabs().row_x[k].iter().collect(); + let zs: Vec = stn.tableau.stabs().row_z[k].iter().collect(); + let s_m = stn.tableau.stabs().signs_minus.contains(k); + let s_i = stn.tableau.stabs().signs_i.contains(k); + eprintln!("stab {k}: x={xs:?} z={zs:?} -={s_m} i={s_i}"); + } + let mps_sv = stn.mps.state_vector(); + eprintln!( + "mps: {:?}", + mps_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + eprintln!("flags: {:?}", stn.disent_flags); + + stn.rz(Angle64::from_radians(1.4326), &[q0]); + + eprintln!("\n=== After inner RZ(1.4326, 0) ==="); + for k in 0..2 { + let xs: Vec = stn.tableau.destabs().row_x[k].iter().collect(); + let zs: Vec = stn.tableau.destabs().row_z[k].iter().collect(); + let s_m = stn.tableau.destabs().signs_minus.contains(k); + let s_i = stn.tableau.destabs().signs_i.contains(k); + eprintln!("destab {k}: x={xs:?} z={zs:?} -={s_m} i={s_i}"); + } + for k in 0..2 { + let xs: Vec = stn.tableau.stabs().row_x[k].iter().collect(); + let zs: Vec = stn.tableau.stabs().row_z[k].iter().collect(); + let s_m = stn.tableau.stabs().signs_minus.contains(k); + let s_i = stn.tableau.stabs().signs_i.contains(k); + eprintln!("stab {k}: x={xs:?} z={zs:?} -={s_m} i={s_i}"); + } + let mps_sv = stn.mps.state_vector(); + eprintln!( + "mps: {:?}", + mps_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + } + + /// Direct comparison: std path (flags cleared) vs `DenseStateVec` for seed 107 setup. + /// Does std implement `U_goal` correctly? + #[test] + #[allow(clippy::type_complexity)] + fn test_std_vs_ref_seed_107() { + use pecos_simulators::DenseStateVec; + let q0 = QubitId(0); + let q1 = QubitId(1); + let mut stn = StabMps::new(2); + let mut ref_sim = DenseStateVec::new(2); + + let apply_both = |_stn: &mut StabMps, + _ref_sim: &mut DenseStateVec, + gate: &dyn Fn( + &mut dyn FnMut(&mut StabMps), + &mut dyn FnMut(&mut DenseStateVec), + )| { + let mut s_closure = |s: &mut StabMps| { + let _ = s; + }; + let mut r_closure = |r: &mut DenseStateVec| { + let _ = r; + }; + gate(&mut s_closure, &mut r_closure); + }; + let _ = apply_both; + + stn.cx(&[(q0, q1)]); + ref_sim.cx(&[(q0, q1)]); + stn.sz(&[q1]); + ref_sim.sz(&[q1]); + stn.rz(Angle64::from_radians(4.8946), &[q1]); + ref_sim.rz(Angle64::from_radians(4.8946), &[q1]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q0]); + ref_sim.rz(Angle64::QUARTER_TURN / 2u64, &[q0]); + stn.cz(&[(q0, q1)]); + ref_sim.cz(&[(q0, q1)]); + stn.x(&[q0]); + ref_sim.x(&[q0]); + stn.rz(Angle64::from_radians(6.0633), &[q1]); + ref_sim.rz(Angle64::from_radians(6.0633), &[q1]); + stn.sz(&[q1]); + ref_sim.sz(&[q1]); + stn.x(&[q1]); + ref_sim.x(&[q1]); + stn.h(&[q0]); + ref_sim.h(&[q0]); + + // Force std path: clear flags. + for i in 0..stn.disent_flags.len() { + stn.disent_flags[i] = None; + } + stn.rz(Angle64::from_radians(1.4326), &[q0]); + ref_sim.rz(Angle64::from_radians(1.4326), &[q0]); + + let sv_stn = stn.state_vector(); + let sv_ref: Vec = (0..4).map(|i| ref_sim.get_amplitude(i)).collect(); + let overlap: Complex64 = sv_stn + .iter() + .zip(sv_ref.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + eprintln!( + "STN std: {:?}", + sv_stn + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + eprintln!( + "REF: {:?}", + sv_ref + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + eprintln!("fid = {}", overlap.norm_sqr()); + assert!( + (overlap.norm_sqr() - 1.0).abs() < 1e-6, + "std path should match DenseStateVec reference: fid={}", + overlap.norm_sqr() + ); + } + + /// Compare YY test setup: disent path vs std path (flags cleared). + /// If they DIVERGE, then the forward right-compose is NOT equivalent to std + /// (even though `test_disentangle_YY_rotation` passes vs true reference — + /// meaning the disent path matches true reference by coincidence, not because + /// it equals std path). + #[test] + fn test_yy_setup_disent_vs_std() { + let theta = Angle64::from_radians(0.3); + let build = || -> StabMps { + let mut s = StabMps::new(2); + s.cx(&[(QubitId(0), QubitId(1))]); + s.sz(&[QubitId(1)]); + s.sz(&[QubitId(0)]); + s.h(&[QubitId(0)]); + s.h(&[QubitId(1)]); + s.sz(&[QubitId(0)]); + s.sz(&[QubitId(1)]); + s + }; + + let mut disent = build(); + disent.rz(theta, &[QubitId(0)]); + let sv_d = disent.state_vector(); + + let mut std = build(); + for i in 0..std.disent_flags.len() { + std.disent_flags[i] = None; + } + std.rz(theta, &[QubitId(0)]); + let sv_s = std.state_vector(); + + let overlap: Complex64 = sv_d + .iter() + .zip(sv_s.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + eprintln!("YY disent vs std fid = {}", overlap.norm_sqr()); + } + + /// Simpler diagnostic: apply each `right_compose` op to tableau, and compare + /// virtual state to applying the same op to MPS directly. These should match + /// per the identity: (C·U)·xvec = C·(U·xvec). + #[test] + fn test_right_compose_equivalence_diagnostic() { + use crate::stab_mps::tableau_compose; + let q0 = QubitId(0); + let q1 = QubitId(1); + + // Build a state with some Clifford ops to get a non-trivial tableau & non-trivial MPS. + let build = || -> StabMps { + let mut s = StabMps::new(2); + s.cx(&[(q0, q1)]); + s.sz(&[q1]); + s.rz(Angle64::from_radians(4.8946), &[q1]); // non-Clifford to get MPS nontrivial + s.rz(Angle64::QUARTER_TURN / 2u64, &[q0]); + s.cz(&[(q0, q1)]); + s.x(&[q0]); + s.rz(Angle64::from_radians(6.0633), &[q1]); + s.sz(&[q1]); + s.x(&[q1]); + s.h(&[q0]); + s + }; + + let sdg_m = { + let mut m = DMatrix::identity(2, 2); + m[(1, 1)] = Complex64::new(0.0, -1.0); + m + }; + let s_m = { + let mut m = DMatrix::identity(2, 2); + m[(1, 1)] = Complex64::new(0.0, 1.0); + m + }; + let h_m = { + let r = Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0); + DMatrix::from_row_slice(2, 2, &[r, r, r, -r]) + }; + let cnot_lo_m = DMatrix::from_row_slice( + 4, + 4, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + + let check = |label: &str, + apply_tableau: &dyn Fn(&mut StabMps), + apply_mps: &dyn Fn(&mut StabMps)| { + let mut s_tab = build(); + apply_tableau(&mut s_tab); + let sv_tab = s_tab.state_vector(); + let mut s_mps = build(); + apply_mps(&mut s_mps); + let sv_mps = s_mps.state_vector(); + let overlap: Complex64 = sv_tab + .iter() + .zip(sv_mps.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + let fid = overlap.norm_sqr(); + eprintln!("{label}: fid(tab vs mps) = {fid:.6}"); + (fid - 1.0).abs() < 1e-6 + }; + + let r_szdg_0 = |s: &mut StabMps| tableau_compose::right_compose_szdg(&mut s.tableau, 0); + let r_szdg_1 = |s: &mut StabMps| tableau_compose::right_compose_szdg(&mut s.tableau, 1); + let r_sz_1 = |s: &mut StabMps| tableau_compose::right_compose_sz(&mut s.tableau, 1); + let r_cx_01 = |s: &mut StabMps| tableau_compose::right_compose_cx(&mut s.tableau, 0, 1); + let r_z_0 = |s: &mut StabMps| tableau_compose::right_compose_z(&mut s.tableau, 0); + let r_h_0 = |s: &mut StabMps| tableau_compose::right_compose_h(&mut s.tableau, 0); + + let sdg_on_0 = |s: &mut StabMps| { + s.mps.apply_one_site_gate(0, &sdg_m).unwrap(); + }; + let sdg_on_1 = |s: &mut StabMps| { + s.mps.apply_one_site_gate(1, &sdg_m).unwrap(); + }; + let s_on_1 = |s: &mut StabMps| { + s.mps.apply_one_site_gate(1, &s_m).unwrap(); + }; + let cnot_01_mps = |s: &mut StabMps| { + s.mps + .apply_long_range_two_site_gate(0, 1, &cnot_lo_m) + .unwrap(); + }; + let z_m = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(-1.0, 0.0), + ], + ); + let z_m_clone = z_m.clone(); + let z_on_0 = move |s: &mut StabMps| { + s.mps.apply_one_site_gate(0, &z_m_clone).unwrap(); + }; + let h_m_clone = h_m.clone(); + let h_on_0 = move |s: &mut StabMps| { + s.mps.apply_one_site_gate(0, &h_m_clone).unwrap(); + }; + + let mut ok = true; + ok &= check("right_compose_szdg(0)", &r_szdg_0, &sdg_on_0); + ok &= check("right_compose_szdg(1)", &r_szdg_1, &sdg_on_1); + ok &= check("right_compose_sz(1)", &r_sz_1, &s_on_1); + ok &= check("right_compose_cx(0,1)", &r_cx_01, &cnot_01_mps); + ok &= check("right_compose_z(0)", &r_z_0, &z_on_0); + ok &= check("right_compose_h(0)", &r_h_0, &h_on_0); + assert!(ok, "some right_compose op fails equivalence"); + } + + /// Compare the disentangle path to the standard (non-disentangle) path by + /// running the exact same setup twice: once with flags enabled, once with + /// flags forced to None. + #[test] + fn test_disentangle_vs_standard_seed_107() { + let q0 = QubitId(0); + let q1 = QubitId(1); + // Build the state at step 8 end (before the failing rx). + let build = || -> StabMps { + let mut s = StabMps::new(2); + s.cx(&[(q0, q1)]); + s.sz(&[q1]); + s.rz(Angle64::from_radians(4.8946), &[q1]); + s.rz(Angle64::QUARTER_TURN / 2u64, &[q0]); + s.cz(&[(q0, q1)]); + s.x(&[q0]); + s.rz(Angle64::from_radians(6.0633), &[q1]); + s.sz(&[q1]); + s.x(&[q1]); + // Start of rx(0, 1.4326): apply inner H(q0). + s.h(&[q0]); + s + }; + + // Run 1: standard flags -> disentangle fires. + let mut s_disent = build(); + s_disent.rz(Angle64::from_radians(1.4326), &[q0]); + let sv_disent = s_disent.state_vector(); + + // Run 2: flags cleared -> uses multi-site CNOT cascade path. + let mut s_std = build(); + for i in 0..s_std.disent_flags.len() { + s_std.disent_flags[i] = None; + } + s_std.rz(Angle64::from_radians(1.4326), &[q0]); + let sv_std = s_std.state_vector(); + + let overlap: Complex64 = sv_disent + .iter() + .zip(sv_std.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + eprintln!( + "disent: {:?}", + sv_disent + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + eprintln!( + "std: {:?}", + sv_std + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + eprintln!("fid(disent vs std) = {}", overlap.norm_sqr()); + assert!( + (overlap.norm_sqr() - 1.0).abs() < 1e-6, + "disentangle path diverges from standard path: fid={}", + overlap.norm_sqr() + ); + } + + /// Exact replay of fuzz seed 107. + /// Gates: cx, sz(1), rz(1) 4.8946, t(0), cz, x(0), rz(1) 6.0633, sz(1), x(1), rx(0) 1.4326. + #[test] + fn test_fuzz_seed_107_exact_replay() { + use pecos_simulators::DenseStateVec; + let mut stn = StabMps::new(2); + let mut ref_sim = DenseStateVec::new(2); + let q0 = QubitId(0); + let q1 = QubitId(1); + + let check = |stn: &StabMps, ref_sim: &mut DenseStateVec, label: &str| { + let stn_sv = stn.state_vector(); + let ref_sv: Vec = (0..4).map(|i| ref_sim.get_amplitude(i)).collect(); + let overlap: Complex64 = stn_sv + .iter() + .zip(ref_sv.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + let fid = overlap.norm_sqr(); + eprintln!("{label}: fid={fid:.6}"); + eprintln!( + " STN: {:?}", + stn_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + eprintln!( + " REF: {:?}", + ref_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + (fid - 1.0).abs() < 1e-6 + }; + + stn.cx(&[(q0, q1)]); + ref_sim.cx(&[(q0, q1)]); + assert!(check(&stn, &mut ref_sim, "step 0 cx")); + stn.sz(&[q1]); + ref_sim.sz(&[q1]); + assert!(check(&stn, &mut ref_sim, "step 1 sz(1)")); + stn.rz(Angle64::from_radians(4.8946), &[q1]); + ref_sim.rz(Angle64::from_radians(4.8946), &[q1]); + assert!(check(&stn, &mut ref_sim, "step 2 rz(1) 4.89")); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q0]); + ref_sim.rz(Angle64::QUARTER_TURN / 2u64, &[q0]); + assert!(check(&stn, &mut ref_sim, "step 3 t(0)")); + stn.cz(&[(q0, q1)]); + ref_sim.cz(&[(q0, q1)]); + assert!(check(&stn, &mut ref_sim, "step 4 cz")); + stn.x(&[q0]); + ref_sim.x(&[q0]); + assert!(check(&stn, &mut ref_sim, "step 5 x(0)")); + stn.rz(Angle64::from_radians(6.0633), &[q1]); + ref_sim.rz(Angle64::from_radians(6.0633), &[q1]); + assert!(check(&stn, &mut ref_sim, "step 6 rz(1) 6.06")); + stn.sz(&[q1]); + ref_sim.sz(&[q1]); + assert!(check(&stn, &mut ref_sim, "step 7 sz(1)")); + stn.x(&[q1]); + ref_sim.x(&[q1]); + assert!(check(&stn, &mut ref_sim, "step 8 x(1)")); + stn.rx(Angle64::from_radians(1.4326), &[q0]); + ref_sim.rx(Angle64::from_radians(1.4326), &[q0]); + assert!(check(&stn, &mut ref_sim, "step 9 rx(0) 1.43")); + } + + #[test] + fn test_disentangle_gf2_recording() { + // H(0), H(1), Rz(theta, 0), Rz(theta, 1) + // Each Rz has a single flip site (no entangling gate between them). + // Disentangling fires on both, recording single-site patterns. + let theta = Angle64::from_radians(0.3); + let mut stn = StabMps::new(2); + + stn.h(&[QubitId(0)]); + stn.h(&[QubitId(1)]); + stn.rz(theta, &[QubitId(0)]); + stn.rz(theta, &[QubitId(1)]); + + // GF(2) matrix should have 2 rows, each a single-site indicator + assert_eq!(stn.gf2_matrix().num_gates(), 2); + assert_eq!(stn.gf2_matrix().gf2_rank(), 2); // Independent sites + } + + #[test] + fn test_stn_clifford_circuit() { + let mut stn = StabMps::new(2); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + + let results0 = stn.mz(&[QubitId(0)]); + let outcome0 = results0[0].outcome; + let determ0 = results0[0].is_deterministic; + + let results1 = stn.mz(&[QubitId(1)]); + let outcome1 = results1[0].outcome; + let determ1 = results1[0].is_deterministic; + + assert!(!determ0); + assert!(determ1); + assert_eq!(outcome0, outcome1); + } + + #[test] + fn test_stn_rz_clifford_angles() { + let mut stn = StabMps::new(1); + stn.h(&[QubitId(0)]); + stn.rz(Angle64::QUARTER_TURN, &[QubitId(0)]); // S gate + assert_eq!(stn.max_bond_dim(), 1); + } + + #[test] + fn test_stn_t_gate_on_zero() { + let mut stn = StabMps::new(1); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); // T = RZ(pi/4) + assert_eq!(stn.max_bond_dim(), 1); + } + + #[test] + fn test_stn_t_gate_on_plus() { + let mut stn = StabMps::new(1); + stn.h(&[QubitId(0)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); // T gate + assert_eq!(stn.max_bond_dim(), 1); + assert_relative_eq!(stn.mps().norm_squared(), 1.0, epsilon = 1e-10); + } + + #[test] + fn test_stn_multiple_t_gates() { + let mut stn = StabMps::new(2); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + assert_relative_eq!(stn.mps().norm_squared(), 1.0, epsilon = 1e-8); + } + + #[test] + fn test_stn_reset() { + let mut stn = StabMps::new(2); + stn.h(&[QubitId(0)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + stn.reset(); + assert_eq!(stn.max_bond_dim(), 1); + } + + // --- Cross-validation tests against StabVec --- + + /// Helper: compare STN state vector against `StabVec` state vector. + /// Allows global phase difference: checks that ||^2 ≈ 1 + /// and that both are normalized. + fn assert_state_vectors_match(stn_sv: &[Complex64], crz_sv: &[Complex64], label: &str) { + assert_eq!(stn_sv.len(), crz_sv.len(), "{label}: dimension mismatch"); + + // Check both are normalized + let norm_stn: f64 = stn_sv.iter().map(nalgebra::Complex::norm_sqr).sum(); + let norm_crz: f64 = crz_sv.iter().map(nalgebra::Complex::norm_sqr).sum(); + assert_relative_eq!(norm_stn, 1.0, epsilon = 1e-6); + assert_relative_eq!(norm_crz, 1.0, epsilon = 1e-6); + + // Check overlap ||^2 == 1 (states are the same up to global phase) + let overlap: Complex64 = stn_sv + .iter() + .zip(crz_sv.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + assert_relative_eq!(overlap.norm_sqr(), 1.0, epsilon = 1e-6); + } + + #[test] + fn test_cross_validate_pure_clifford() { + // H on q0, CX(q0, q1) -> Bell state + let mut stn = StabMps::new(2); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + let stn_sv = stn.state_vector(); + + let mut crz = StabVec::builder(2).seed(42).build(); + crz.h(&[QubitId(0)]); + crz.cx(&[(QubitId(0), QubitId(1))]); + let crz_sv = crz.state_vector(); + + assert_state_vectors_match(&stn_sv, &crz_sv, "Bell state"); + } + + #[test] + fn test_cross_validate_t_on_plus() { + // H then T on single qubit + let mut stn = StabMps::new(1); + stn.h(&[QubitId(0)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let stn_sv = stn.state_vector(); + + let mut crz = StabVec::builder(1).seed(42).build(); + crz.h(&[QubitId(0)]); + crz.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let crz_sv = crz.state_vector(); + + assert_state_vectors_match(&stn_sv, &crz_sv, "T|+>"); + } + + #[test] + fn test_cross_validate_t_on_zero() { + // T on |0> + let mut stn = StabMps::new(1); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let stn_sv = stn.state_vector(); + + let mut crz = StabVec::builder(1).seed(42).build(); + crz.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let crz_sv = crz.state_vector(); + + assert_state_vectors_match(&stn_sv, &crz_sv, "T|0>"); + } + + #[test] + fn test_cross_validate_bell_plus_t() { + // Bell state then T on q0 + let mut stn = StabMps::new(2); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let stn_sv = stn.state_vector(); + + let mut crz = StabVec::builder(2).seed(42).build(); + crz.h(&[QubitId(0)]); + crz.cx(&[(QubitId(0), QubitId(1))]); + crz.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let crz_sv = crz.state_vector(); + + assert_state_vectors_match(&stn_sv, &crz_sv, "Bell + T"); + } + + #[test] + fn test_cross_validate_rz_arbitrary_angle() { + // RZ at non-Clifford, non-T angle + let theta = Angle64::from_radians(1.234); + let mut stn = StabMps::new(1); + stn.h(&[QubitId(0)]); + stn.rz(theta, &[QubitId(0)]); + let stn_sv = stn.state_vector(); + + let mut crz = StabVec::builder(1).seed(42).build(); + crz.h(&[QubitId(0)]); + crz.rz(theta, &[QubitId(0)]); + let crz_sv = crz.state_vector(); + + assert_state_vectors_match(&stn_sv, &crz_sv, "RZ(1.234)|+>"); + } + + #[test] + fn test_cross_validate_multiple_rz() { + // H, T, H, T on single qubit (two non-Clifford layers) + let t_angle = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::new(1); + stn.h(&[QubitId(0)]); + stn.rz(t_angle, &[QubitId(0)]); + stn.h(&[QubitId(0)]); + stn.rz(t_angle, &[QubitId(0)]); + let stn_sv = stn.state_vector(); + + let mut crz = StabVec::builder(1).seed(42).build(); + crz.h(&[QubitId(0)]); + crz.rz(t_angle, &[QubitId(0)]); + crz.h(&[QubitId(0)]); + crz.rz(t_angle, &[QubitId(0)]); + let crz_sv = crz.state_vector(); + + assert_state_vectors_match(&stn_sv, &crz_sv, "H T H T |0>"); + } + + #[test] + fn test_cross_validate_two_t_gates_2qubit() { + // Two T gates on different qubits: H(0), H(1), T(0), T(1) + let t_angle = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::new(2); + stn.h(&[QubitId(0)]); + stn.h(&[QubitId(1)]); + stn.rz(t_angle, &[QubitId(0)]); + stn.rz(t_angle, &[QubitId(1)]); + let stn_sv = stn.state_vector(); + + let mut crz = StabVec::builder(2).seed(42).build(); + crz.h(&[QubitId(0)]); + crz.h(&[QubitId(1)]); + crz.rz(t_angle, &[QubitId(0)]); + crz.rz(t_angle, &[QubitId(1)]); + let crz_sv = crz.state_vector(); + + assert_state_vectors_match(&stn_sv, &crz_sv, "H H T T (2 qubits, product state)"); + } + + #[test] + fn test_cross_validate_3qubit_circuit() { + // 3-qubit circuit with Cliffords and T gates + let t_angle = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::new(3); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.rz(t_angle, &[QubitId(0)]); + stn.h(&[QubitId(2)]); + stn.cx(&[(QubitId(1), QubitId(2))]); + + stn.rz(t_angle, &[QubitId(2)]); + let stn_sv = stn.state_vector(); + + let mut crz = StabVec::builder(3).seed(42).build(); + crz.h(&[QubitId(0)]); + crz.cx(&[(QubitId(0), QubitId(1))]); + crz.rz(t_angle, &[QubitId(0)]); + crz.h(&[QubitId(2)]); + crz.cx(&[(QubitId(1), QubitId(2))]); + crz.rz(t_angle, &[QubitId(2)]); + let crz_sv = crz.state_vector(); + assert_state_vectors_match(&stn_sv, &crz_sv, "3-qubit circuit"); + } + + #[test] + fn test_cross_validate_s_gate_via_rz() { + // RZ(pi/2) should match S gate + let mut stn = StabMps::new(1); + stn.h(&[QubitId(0)]); + stn.rz(Angle64::QUARTER_TURN, &[QubitId(0)]); // S = RZ(pi/2) + let stn_sv = stn.state_vector(); + + let mut crz = StabVec::builder(1).seed(42).build(); + crz.h(&[QubitId(0)]); + crz.rz(Angle64::QUARTER_TURN, &[QubitId(0)]); + let crz_sv = crz.state_vector(); + + assert_state_vectors_match(&stn_sv, &crz_sv, "S|+> via RZ"); + } + + // --- Measurement tests --- + + #[test] + fn test_measurement_after_t_gate() { + // H, T, measure in Z basis. + // T|+> = (e^{-i*pi/8}|0> + e^{i*pi/8}|1>)/sqrt(2) + // Both amplitudes have magnitude 1/sqrt(2), so prob(0) = prob(1) = 0.5 + let expected_p0 = 0.5; + + let n_trials: u32 = 2000; + let mut count_0 = 0; + for trial in 0..n_trials { + let mut stn = StabMps::with_seed(1, u64::from(1000 + trial)); + stn.h(&[QubitId(0)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let result = stn.mz(&[QubitId(0)]); + if !result[0].outcome { + count_0 += 1; + } + } + let measured_p0 = f64::from(count_0) / f64::from(n_trials); + assert!( + (measured_p0 - expected_p0).abs() < 0.05, + "p(0) = {measured_p0:.3}, expected {expected_p0:.3}" + ); + } + + #[test] + fn test_measurement_rx_probabilities() { + // RX(pi/3)|0> has prob(0) = cos^2(pi/6) = 3/4 + let expected_p0 = 0.75; + let theta = Angle64::from_radians(std::f64::consts::FRAC_PI_3); + + let n_trials: u32 = 2000; + let mut count_0 = 0; + for trial in 0..n_trials { + let mut stn = StabMps::with_seed(1, u64::from(3000 + trial)); + stn.rx(theta, &[QubitId(0)]); + let result = stn.mz(&[QubitId(0)]); + if !result[0].outcome { + count_0 += 1; + } + } + let measured_p0 = f64::from(count_0) / f64::from(n_trials); + assert!( + (measured_p0 - expected_p0).abs() < 0.05, + "p(0) = {measured_p0:.3}, expected {expected_p0:.3}" + ); + } + + #[test] + fn test_measurement_deterministic_after_t_on_zero() { + // T|0> is still an eigenstate of Z (Z is a stabilizer of |0>) + let mut stn = StabMps::with_seed(1, 42); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let result = stn.mz(&[QubitId(0)]); + assert!(result[0].is_deterministic); + assert!(!result[0].outcome); // +1 eigenvalue -> outcome false + } + + #[test] + fn test_measurement_bell_state_correlation() { + // Bell state: measure q0, then q1 should give same outcome + for trial in 0..50 { + let mut stn = StabMps::with_seed(2, 2000 + trial); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + // Apply T to make MPS non-trivial + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + + let r0 = stn.mz(&[QubitId(0)])[0].outcome; + let r1 = stn.mz(&[QubitId(1)])[0].outcome; + assert_eq!( + r0, r1, + "trial {trial}: Bell state + T should have correlated measurements" + ); + } + } + + #[test] + fn test_disentangle_preserves_state() { + // Create a circuit, disentangle, verify state vector is unchanged. + let t_angle = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::new(3); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.rz(t_angle, &[QubitId(0)]); + stn.h(&[QubitId(2)]); + stn.cx(&[(QubitId(1), QubitId(2))]); + stn.rz(t_angle, &[QubitId(2)]); + + // Get state vector before disentangling + let sv_before = stn.state_vector(); + let bond_before = stn.max_bond_dim(); + + // Disentangle + let gates_applied = stn.disentangle(3); + eprintln!( + "Disentangle: applied {gates_applied} gates, bond dim {} -> {}", + bond_before, + stn.max_bond_dim() + ); + + // State vector should be unchanged (up to global phase) + let sv_after = stn.state_vector(); + let overlap: Complex64 = sv_before + .iter() + .zip(sv_after.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + eprintln!("overlap = {:.6}", overlap.norm_sqr()); + assert_state_vectors_match(&sv_before, &sv_after, "disentangle preserves state"); + + // Bond dimension should not have increased + assert!( + stn.max_bond_dim() <= bond_before, + "disentangle should not increase bond dim: {} > {}", + stn.max_bond_dim(), + bond_before + ); + + eprintln!( + "Disentangle: applied {gates_applied} gates, bond dim {} -> {}", + bond_before, + stn.max_bond_dim() + ); + } + + #[test] + fn test_compression_keeps_bond_dim_bounded() { + // Apply multiple T gates. Without compression, bond dim would grow + // exponentially. With compression, redundant components are removed. + let t_angle = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::builder(4).max_bond_dim(4).build(); + + // Create entangled state + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.h(&[QubitId(2)]); + stn.cx(&[(QubitId(2), QubitId(3))]); + + // Apply T gates -- each one could double bond dim without compression + stn.rz(t_angle, &[QubitId(0)]); + stn.rz(t_angle, &[QubitId(2)]); + stn.rz(t_angle, &[QubitId(1)]); + stn.rz(t_angle, &[QubitId(3)]); + + // Bond dimension should be bounded by max_bond_dim + assert!( + stn.max_bond_dim() <= 4, + "bond dim {} should be <= 4", + stn.max_bond_dim() + ); + + // State should still be approximately normalized + assert!( + (stn.mps().norm_squared() - 1.0).abs() < 0.1, + "norm should be close to 1, got {}", + stn.mps().norm_squared() + ); + } + + #[test] + fn test_pauli_expectation_z_on_zero_state() { + // ⟨0|Z|0⟩ = 1. + let stn = StabMps::new(2); + let v = stn.pauli_expectation(&[(0, PauliKind::Z)]); + assert!((v - 1.0).abs() < 1e-10); + } + + #[test] + fn test_pauli_expectation_z_on_one_state() { + // ⟨1|Z|1⟩ = -1. + let mut stn = StabMps::new(2); + stn.x(&[QubitId(0)]); + let v = stn.pauli_expectation(&[(0, PauliKind::Z)]); + assert!((v + 1.0).abs() < 1e-10); + } + + #[test] + fn test_pauli_expectation_x_on_plus_state() { + // ⟨+|X|+⟩ = 1. + let mut stn = StabMps::new(2); + stn.h(&[QubitId(0)]); + let v = stn.pauli_expectation(&[(0, PauliKind::X)]); + assert!((v - 1.0).abs() < 1e-10); + } + + #[test] + fn test_sample_bitstring_plus_state() { + // |+⟩ on q0, |0⟩ on q1: shots should be 50/50 for q0, always 0 for q1. + let mut stn = StabMps::with_seed(2, 99); + stn.h(&[QubitId(0)]); + let shots = stn.sample_bitstring(200); + let q0_one_count = shots.iter().filter(|bs| bs[0]).count(); + let q1_one_count = shots.iter().filter(|bs| bs[1]).count(); + assert_eq!(q1_one_count, 0, "q1 must always measure 0"); + assert!( + q0_one_count > 70 && q0_one_count < 130, + "q0 should be ~50/50, got {q0_one_count}/200" + ); + } + + #[test] + fn test_sample_bitstring_bell_correlation() { + // Bell state: each shot is either (0,0) or (1,1). Sample 200 + // shots, verify all are correlated. + let mut stn = StabMps::with_seed(2, 99); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + let shots = stn.sample_bitstring(200); + for (i, bs) in shots.iter().enumerate() { + assert_eq!(bs[0], bs[1], "shot {i} not Bell-correlated: {bs:?}"); + } + let zero_count = shots.iter().filter(|bs| !bs[0]).count(); + assert!( + zero_count > 60 && zero_count < 140, + "zero_count {zero_count}/200 outside 60..140" + ); + } + + #[test] + fn test_sample_bitstring_does_not_mutate_state() { + // Verify the simulator state is unchanged after sampling. + let mut stn = StabMps::with_seed(3, 42); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + let bond_before = stn.max_bond_dim(); + let _ = stn.sample_bitstring(10); + let bond_after = stn.max_bond_dim(); + // Self-state untouched. + assert_eq!( + bond_before, bond_after, + "sample_bitstring mutated simulator state" + ); + } + + #[test] + fn test_auto_grow_bond_dim_starts_low_grows_when_capped() { + // Build a small-cap STN and exercise it with a deep, adversarial + // T circuit (small angle that defeats disent flag) so the cap + // binds. Auto-grow should kick in. + let n = 6; + let mut stn = StabMps::builder(n) + .seed(42) + .max_bond_dim(2) + .auto_grow_bond_dim(1e-15) // any truncation triggers + .auto_grow_max_bond_dim(64) + .build(); + + // Initial state: spread into GHZ-like entanglement + for q in 0..n { + stn.h(&[QubitId(q)]); + } + for q in 0..n - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + // Deeper T-heavy circuit with rotating qubits + interleaved CXs + // so the disent flag mechanism can't absorb the T's into the + // tableau cheaply. Forces real MPS bond growth. + let small = Angle64::from_radians(0.37); + for layer in 0..6 { + for q in 0..n { + stn.rz(small, &[QubitId((q + layer) % n)]); + } + for q in 0..n - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + } + // After deep mixing, cap should have hit AND been raised. + assert!( + stn.config.max_bond_dim > 2, + "auto-grow should have raised cap from 2; current = {} (bond_cap_hits={}, trunc={:.2e})", + stn.config.max_bond_dim, + stn.bond_cap_hits(), + stn.truncation_error(), + ); + assert!(stn.config.max_bond_dim <= 64); + } + + #[test] + fn test_auto_grow_bond_dim_disabled_by_default() { + let n = 4; + let mut stn = StabMps::builder(n).seed(99).max_bond_dim(2).build(); + // No auto_grow_bond_dim builder call → disabled. + for q in 0..n { + stn.h(&[QubitId(q)]); + } + for q in 0..n - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + let t = Angle64::QUARTER_TURN / 2u64; + for q in 0..n { + stn.rz(t, &[QubitId(q)]); + } + // Cap stays at 2. + assert_eq!(stn.config.max_bond_dim, 2); + } + + #[test] + fn test_pauli_expectation_product_pauli_per_qubit() { + // Exercise decompose_pauli_string's per-qubit Pauli multiplication: + // (q, X), (q, Y) → X·Y = iZ at q. Phase contribution should come through. + // <0|X·Y|0> = <0|iZ|0> = i. Real part = 0. + let stn = StabMps::new(1); + let v = stn.pauli_expectation(&[(0, PauliKind::X), (0, PauliKind::Y)]); + // XY = iZ; <0|iZ|0> = i; pauli_expectation returns real part = 0. + assert!(v.abs() < 1e-10, "<0|XY|0> real part should be 0, got {v}"); + } + + #[test] + fn test_pauli_expectation_yy_per_qubit_is_identity() { + // (q, Y), (q, Y) → Y² = I. <0|I|0> = 1. + let stn = StabMps::new(1); + let v = stn.pauli_expectation(&[(0, PauliKind::Y), (0, PauliKind::Y)]); + assert!((v - 1.0).abs() < 1e-10, "<0|YY|0> = 1, got {v}"); + } + + #[test] + fn test_pauli_expectation_z_on_one_via_apply_x() { + // Apply X to a plain state, measure Z: should give -1. + let mut stn = StabMps::new(1); + stn.x(&[QubitId(0)]); + let v = stn.pauli_expectation(&[(0, PauliKind::Z)]); + assert!((v + 1.0).abs() < 1e-10, "<1|Z|1> = -1, got {v}"); + } + + #[test] + fn test_pauli_frame_with_lazy_measure() { + // Lazy measure + Pauli frame should compose: frame applies AFTER + // the measurement outcome, irrespective of lazy/eager internals. + // Init |0⟩, inject X in frame, measure: expect outcome=1 regardless + // of lazy_measure setting. + for lazy in [false, true] { + let mut stn = StabMps::builder(1) + .seed(42) + .lazy_measure(lazy) + .pauli_frame_tracking(true) + .build(); + stn.inject_x_in_frame(QubitId(0)); + let r = stn.mz(&[QubitId(0)])[0].outcome; + assert!( + r, + "lazy_measure={lazy}, frame X should give outcome=1, got {r}" + ); + } + } + + #[test] + fn test_pauli_frame_with_merge_rz() { + // Inject frame X on q0, apply rz(theta) with merge_rz on. + // X·RZ(θ) = RZ(-θ)·X. Since frame X is "virtual" (will be applied + // at measurement), the simulated state should evolve under RZ(θ) + // naturally — but the NET physical state differs from + // "simulated + frame" only by a global phase (e^{-iθ} on X|ψ>). + // + // Consequence: measurement outcome distributions are identical + // between frame-tracking and no-frame-tracking paths for + // Z-basis measurements. Verify. + let theta = Angle64::from_radians(0.7); + let mut stn_frame = StabMps::builder(1) + .seed(5) + .merge_rz(true) + .pauli_frame_tracking(true) + .build(); + stn_frame.h(&[QubitId(0)]); + stn_frame.inject_x_in_frame(QubitId(0)); + stn_frame.rz(theta, &[QubitId(0)]); + stn_frame.h(&[QubitId(0)]); + let results_frame = stn_frame.mz(&[QubitId(0)]); + let outcome_frame = results_frame[0].outcome; + + // Reference: apply X explicitly (no frame), same sequence. + let mut stn_ref = StabMps::builder(1).seed(5).build(); + stn_ref.h(&[QubitId(0)]); + stn_ref.x(&[QubitId(0)]); + stn_ref.rz(theta, &[QubitId(0)]); + stn_ref.h(&[QubitId(0)]); + let results_ref = stn_ref.mz(&[QubitId(0)]); + let outcome_ref = results_ref[0].outcome; + + assert_eq!( + outcome_frame, outcome_ref, + "frame-X vs applied-X should give same measurement outcome" + ); + } + + #[test] + fn test_is_state_exact_detects_all_sources_of_drift() { + let mut stn = StabMps::builder(2) + .seed(7) + .merge_rz(true) + .pauli_frame_tracking(true) + .build(); + assert!(stn.is_state_exact(), "fresh builder state should be exact"); + + // Pending merged RZ makes it non-exact. + stn.h(&[QubitId(0)]); + stn.rz(Angle64::from_radians(0.5), &[QubitId(0)]); + assert!(!stn.is_state_exact(), "pending merged RZ → not exact"); + stn.flush(); + assert!(stn.is_state_exact(), "after flush() → exact again"); + + // Frame injection makes it non-exact. + stn.inject_x_in_frame(QubitId(0)); + assert!(!stn.is_state_exact(), "frame X set → not exact"); + stn.flush_pauli_frame_to_state(); + assert!(stn.is_state_exact(), "after frame flush → exact"); + } + + #[test] + fn test_pragmatic_drift_count_tracks_non_lazy_pre_reduce() { + // Build a state where col_x for the measured qubit has multiple + // anticommuting stabilizers so pre_reduce fires. H(0), H(1), CX(0,1) + // gives stabs {X_0X_1, X_1}; measuring qubit 1 has col_x[1].len()=2. + let mut stn = StabMps::builder(2).seed(3).build(); + stn.h(&[QubitId(0)]); + stn.h(&[QubitId(1)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + assert_eq!(stn.pragmatic_drift_count(), 0, "no measurements yet"); + let _ = stn.mz(&[QubitId(1)]); + assert_eq!( + stn.pragmatic_drift_count(), + 1, + "non-lazy mz on multi-anticom col_x should bump drift counter" + ); + assert!( + !stn.is_state_exact(), + "pragmatic drift makes stored state non-exact" + ); + + // Lazy path: same setup but no drift (pre_reduce CNOTs go into V). + let mut stn = StabMps::builder(2).seed(3).lazy_measure(true).build(); + stn.h(&[QubitId(0)]); + stn.h(&[QubitId(1)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + let _ = stn.mz(&[QubitId(1)]); + assert_eq!( + stn.pragmatic_drift_count(), + 0, + "lazy_measure path must not increment drift count" + ); + + // Reset clears the counter. + let mut stn = StabMps::builder(2).seed(3).build(); + stn.h(&[QubitId(0)]); + stn.h(&[QubitId(1)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + let _ = stn.mz(&[QubitId(1)]); + assert!(stn.pragmatic_drift_count() > 0); + stn.reset(); + assert_eq!(stn.pragmatic_drift_count(), 0, "reset clears drift counter"); + } + + #[test] + fn test_lazy_measure_imaginary_sp_y_eigenstate() { + // To hit the imaginary-sp branch we need `id` (flip_site) to also + // appear in `sign_sites`, meaning both stab and destab have the X + // bit at the measured qubit. Circuit: SZ(0), H(0), CX(0,1) gives + // stab = X_0·X_1 (X-bit at 0) and destab = -Y_0·X_1 (X-bit at 0). + // CX(0,1) entangles → MPS non-trivial → decompose_z path fires. + // + // Expected: ~50/50 outcome on qubit 0, post-collapse re-measurement + // deterministic and matching. + let num_shots = 400; + let mut zero_count = 0; + let mut one_count = 0; + let t = Angle64::QUARTER_TURN / 2u64; + for shot in 0..num_shots { + let mut stn = StabMps::builder(2).seed(shot).lazy_measure(true).build(); + // Non-Clifford first to force MPS non-trivial (Cliffords alone + // keep MPS in its initial product form via tableau routing). + stn.h(&[QubitId(1)]); + stn.rz(t, &[QubitId(1)]); + stn.sz(&[QubitId(0)]); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + let r1 = stn.mz(&[QubitId(0)])[0].outcome; + let r2 = stn.mz(&[QubitId(0)]); + assert_eq!( + r2[0].outcome, r1, + "after collapse, Z measurement must be stable (shot {shot})" + ); + assert!( + r2[0].is_deterministic, + "post-collapse measurement must be deterministic (shot {shot})" + ); + if r1 { + one_count += 1; + } else { + zero_count += 1; + } + } + assert!( + zero_count > 130 && zero_count < 270, + "qubit 0 should give ~50/50: got {zero_count} zeros, {one_count} ones" + ); + } + + #[test] + fn test_flush_pauli_frame_to_state_makes_read_correct() { + // Without flush: state_vector shows |0⟩ (sim state) even though + // frame has X (physical state is |1⟩). After flush: state_vector + // correctly shows |1⟩. + let mut stn = StabMps::builder(1) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_x_in_frame(QubitId(0)); + // State vector BEFORE flush: frame-bits aren't in the state. + let sv_before = stn.state_vector(); + // Stored state is still |0⟩ (index 0, real amplitude 1). + assert!( + (sv_before[0].re - 1.0).abs() < 1e-10, + "before flush: {sv_before:?}" + ); + assert!(sv_before[1].norm() < 1e-10); + + // Now flush. State should become |1⟩. + stn.flush_pauli_frame_to_state(); + assert!(!stn.frame_x_bit(QubitId(0)), "frame cleared after flush"); + let sv_after = stn.state_vector(); + assert!( + sv_after[0].norm() < 1e-10, + "post-flush q0 amp at |0⟩: {sv_after:?}" + ); + assert!( + (sv_after[1].re - 1.0).abs() < 1e-10, + "post-flush q0 amp at |1⟩: {sv_after:?}" + ); + } + + #[test] + fn test_pauli_frame_inject_x_flips_measurement() { + // Init |0⟩. Inject X in frame → measurement should give 1. + let mut stn = StabMps::builder(1) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_x_in_frame(QubitId(0)); + let r = stn.mz(&[QubitId(0)])[0].outcome; + assert!(r, "X in frame on |0⟩ should measure as 1, got {r}"); + } + + #[test] + fn test_pauli_frame_inject_z_no_effect_on_zero_state() { + // Z on |0⟩ gives |0⟩ (eigenstate). Measurement = 0 still. + let mut stn = StabMps::builder(1) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_z_in_frame(QubitId(0)); + let r = stn.mz(&[QubitId(0)])[0].outcome; + assert!(!r, "Z in frame on |0⟩ should measure 0 (Z|0⟩=|0⟩), got {r}"); + } + + #[test] + fn test_pauli_frame_h_swaps_x_z() { + // Inject Z in frame, apply H, measure. H·Z = X·H. So X bit set, + // Z bit cleared after H. Measurement of X on |0⟩... hmm, but state + // isn't an eigenstate of X. Actually we're tracking Paulis via frame. + // Before H: frame = Z. After H: frame = X (per propagation). + // Physical state |0⟩, measurement in Z basis: frame has Z=0 so + // outcome matches underlying quantum outcome (0). + let mut stn = StabMps::builder(1) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_z_in_frame(QubitId(0)); + stn.h(&[QubitId(0)]); // frame: Z → X after H + assert!(stn.frame_x_bit(QubitId(0))); + assert!(!stn.frame_z_bit(QubitId(0))); + } + + #[test] + fn test_pauli_frame_y_inject_flush_gives_correct_amplitude_phase() { + // Inject Y on qubit 0 (|0⟩). Y|0⟩ = i|1⟩. After flushing, the + // state vector should show amplitude i at index 1 (not -i or 1 or -1). + let mut stn = StabMps::builder(1) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_y_in_frame(QubitId(0)); + stn.flush_pauli_frame_to_state(); + let sv = stn.state_vector(); + assert!(sv[0].norm() < 1e-10, "post-Y at |0⟩ amp: {:?}", sv[0]); + assert!( + (sv[1] - Complex64::new(0.0, 1.0)).norm() < 1e-10, + "post-Y at |1⟩ amp should be +i, got {:?}", + sv[1] + ); + } + + #[test] + fn test_pauli_frame_h_on_y_exact_state_vector() { + // Inject Y on |0⟩, apply H → physical = H·Y·|0⟩ = H·(i|1⟩) = i·|-⟩. + // The decomposition-based flush (applies the frame Pauli to MPS via + // C†·P·C = phase·X_flip·Z_sign rather than to the tableau via tab.y) + // recovers the correct global phase — no ±1 residual. + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + let mut stn = StabMps::builder(1) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_y_in_frame(QubitId(0)); + stn.h(&[QubitId(0)]); + stn.flush_pauli_frame_to_state(); + let sv = stn.state_vector(); + // Expected i·|-⟩ = (i/√2)|0⟩ + (-i/√2)|1⟩. + let expect_0 = Complex64::new(0.0, inv_sqrt2); + let expect_1 = Complex64::new(0.0, -inv_sqrt2); + assert!( + (sv[0] - expect_0).norm() < 1e-10, + "amp |0⟩: expected {expect_0:?}, got {:?}", + sv[0] + ); + assert!( + (sv[1] - expect_1).norm() < 1e-10, + "amp |1⟩: expected {expect_1:?}, got {:?}", + sv[1] + ); + } + + #[test] + fn test_pauli_frame_y_inject_on_bell_state_exact_phase() { + // Φ+ = (|00⟩+|11⟩)/√2. Apply frame Y_0: + // Y_0|00⟩ = i|1⟩_{q0}|0⟩_{q1} = i·(q0=1,q1=0) → LSB index 1. + // Y_0|11⟩ = -i|0⟩_{q0}|1⟩_{q1} = -i·(q0=0,q1=1) → LSB index 2. + // So sv[1] = i/√2, sv[2] = -i/√2, others 0. (Equivalent to -i·Ψ-.) + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + let mut stn = StabMps::builder(2) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.inject_y_in_frame(QubitId(0)); + stn.flush_pauli_frame_to_state(); + let sv = stn.state_vector(); + let expect_1 = Complex64::new(0.0, inv_sqrt2); + let expect_2 = Complex64::new(0.0, -inv_sqrt2); + assert!(sv[0].norm() < 1e-10, "|00⟩: {:?}", sv[0]); + assert!((sv[1] - expect_1).norm() < 1e-10, "sv[1]: {:?}", sv[1]); + assert!((sv[2] - expect_2).norm() < 1e-10, "sv[2]: {:?}", sv[2]); + assert!(sv[3].norm() < 1e-10, "|11⟩: {:?}", sv[3]); + } + + #[test] + fn test_pauli_frame_propagation_preserves_signs() { + // Sanity: even though the state_vector is now exact via flush, the + // propagation signs are still correctly recorded in pauli_frame_phase. + let mut stn = StabMps::builder(1) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_y_in_frame(QubitId(0)); + stn.h(&[QubitId(0)]); + // H·Y·H = -Y: propagation should record -1 in pauli_frame_phase. + assert!( + (stn.pauli_frame_phase + Complex64::new(1.0, 0.0)).norm() < 1e-12, + "H-on-Y should record phase -1, got {:?}", + stn.pauli_frame_phase + ); + assert!(stn.frame_x_bit(QubitId(0))); + assert!(stn.frame_z_bit(QubitId(0))); + } + + #[test] + fn test_reset_qubit_forces_zero_from_one() { + // Prepare |1⟩ then reset → should land on |0⟩ and report outcome=1. + let mut stn = StabMps::builder(1).seed(42).build(); + stn.x(&[QubitId(0)]); + let phys = stn.reset_qubit(QubitId(0)); + assert!(phys, "reset from |1⟩ should report physical outcome true"); + // Post-reset measurement must give 0 (deterministic). + let r = stn.mz(&[QubitId(0)]); + assert!(!r[0].outcome, "after reset, mz must give 0"); + assert!(r[0].is_deterministic, "post-reset mz must be deterministic"); + } + + #[test] + fn test_reset_qubit_forces_zero_from_plus() { + // Prepare |+⟩ then reset. Outcome is random (50/50) but after + // reset, state is deterministically |0⟩. + let mut stn = StabMps::builder(1).seed(42).build(); + stn.h(&[QubitId(0)]); + stn.reset_qubit(QubitId(0)); + let r = stn.mz(&[QubitId(0)]); + assert!(!r[0].outcome, "after reset from |+⟩, mz must give 0"); + assert!(r[0].is_deterministic); + } + + #[test] + fn test_reset_qubit_clears_frame_bits() { + let mut stn = StabMps::builder(1) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_y_in_frame(QubitId(0)); + assert!(stn.frame_x_bit(QubitId(0))); + assert!(stn.frame_z_bit(QubitId(0))); + stn.reset_qubit(QubitId(0)); + assert!(!stn.frame_x_bit(QubitId(0)), "reset must clear frame X"); + assert!(!stn.frame_z_bit(QubitId(0)), "reset must clear frame Z"); + // And the physical state is |0⟩. + let r = stn.mz(&[QubitId(0)]); + assert!(!r[0].outcome, "post-reset mz must give 0"); + } + + #[test] + fn test_reset_qubit_preserves_other_qubits() { + // Entangle q0-q1, then reset q0. q1 should still have a definite + // outcome consistent with the GHZ-like correlation collapsed by + // the reset-measurement. + for shot in 0..20u64 { + let mut stn = StabMps::builder(2).seed(100 + shot).build(); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + let phys = stn.reset_qubit(QubitId(0)); + // q1 should collapse to match phys (Bell correlation). + let r1 = stn.mz(&[QubitId(1)]); + assert!( + r1[0].is_deterministic, + "q1 post-Bell-reset must be deterministic" + ); + assert_eq!( + r1[0].outcome, phys, + "Bell correlation: q1 outcome must match reset's physical outcome" + ); + } + } + + #[test] + fn test_px_gives_plus_state() { + // px should land qubit in |+⟩: X measurement deterministic 0. + let mut stn = StabMps::builder(1).seed(42).build(); + stn.px(QubitId(0)); + // Measure in X basis via H + mz. + stn.h(&[QubitId(0)]); + let r = stn.mz(&[QubitId(0)]); + assert!(!r[0].outcome, "|+⟩ in X-basis should measure 0"); + assert!(r[0].is_deterministic); + } + + #[test] + fn test_extract_syndromes_steane_noiseless() { + // Steane [[7,1,3]]: prep |0_L⟩, extract syndrome, expect all-zero + // syndrome (codestate is a +1 eigenstate of every generator). + // Uses 7 data + 6 ancillas. + let stabs: Vec> = vec![ + vec![ + (3, PauliKind::X), + (4, PauliKind::X), + (5, PauliKind::X), + (6, PauliKind::X), + ], + vec![ + (1, PauliKind::X), + (2, PauliKind::X), + (5, PauliKind::X), + (6, PauliKind::X), + ], + vec![ + (0, PauliKind::X), + (2, PauliKind::X), + (4, PauliKind::X), + (6, PauliKind::X), + ], + vec![ + (3, PauliKind::Z), + (4, PauliKind::Z), + (5, PauliKind::Z), + (6, PauliKind::Z), + ], + vec![ + (1, PauliKind::Z), + (2, PauliKind::Z), + (5, PauliKind::Z), + (6, PauliKind::Z), + ], + vec![ + (0, PauliKind::Z), + (2, PauliKind::Z), + (4, PauliKind::Z), + (6, PauliKind::Z), + ], + ]; + let ancillas: Vec = (7..13).map(QubitId).collect(); + let mut stn = StabMps::builder(13).seed(42).for_sparse_t().build(); + // Prep Steane |0_L⟩ (pivots 0, 1, 3). + stn.h(&[QubitId(0), QubitId(1), QubitId(3)]); + for (c, t) in [ + (3, 4), + (3, 5), + (3, 6), + (1, 2), + (1, 5), + (1, 6), + (0, 2), + (0, 4), + (0, 6), + ] { + stn.cx(&[(QubitId(c), QubitId(t))]); + } + let syndrome = stn.extract_syndromes(&stabs, &ancillas); + assert_eq!(syndrome.len(), 6); + for (i, &b) in syndrome.iter().enumerate() { + assert!(!b, "noiseless Steane syndrome must be zero, bit {i} = {b}"); + } + // Ancillas must be left in |0⟩ for the next round. + for &a in &ancillas { + let r = stn.mz(&[a]); + assert!( + !r[0].outcome && r[0].is_deterministic, + "ancilla {a:?} not reset after extract_syndromes" + ); + } + } + + #[test] + fn test_extract_syndromes_steane_single_x_error_detects() { + // Same setup, inject X_0 before extraction — expect NON-ZERO + // syndrome on at least one Z-stabilizer. + let stabs: Vec> = vec![ + vec![ + (3, PauliKind::X), + (4, PauliKind::X), + (5, PauliKind::X), + (6, PauliKind::X), + ], + vec![ + (1, PauliKind::X), + (2, PauliKind::X), + (5, PauliKind::X), + (6, PauliKind::X), + ], + vec![ + (0, PauliKind::X), + (2, PauliKind::X), + (4, PauliKind::X), + (6, PauliKind::X), + ], + vec![ + (3, PauliKind::Z), + (4, PauliKind::Z), + (5, PauliKind::Z), + (6, PauliKind::Z), + ], + vec![ + (1, PauliKind::Z), + (2, PauliKind::Z), + (5, PauliKind::Z), + (6, PauliKind::Z), + ], + vec![ + (0, PauliKind::Z), + (2, PauliKind::Z), + (4, PauliKind::Z), + (6, PauliKind::Z), + ], + ]; + let ancillas: Vec = (7..13).map(QubitId).collect(); + let mut stn = StabMps::builder(13).seed(42).for_sparse_t().build(); + stn.h(&[QubitId(0), QubitId(1), QubitId(3)]); + for (c, t) in [ + (3, 4), + (3, 5), + (3, 6), + (1, 2), + (1, 5), + (1, 6), + (0, 2), + (0, 4), + (0, 6), + ] { + stn.cx(&[(QubitId(c), QubitId(t))]); + } + // Inject X_0. Z-stabilizer 3 (ZZZZ on 0,2,4,6) anticommutes → syndrome bit 5 set. + stn.x(&[QubitId(0)]); + let syndrome = stn.extract_syndromes(&stabs, &ancillas); + assert!( + syndrome.iter().skip(3).any(|&b| b), + "X_0 error must trigger at least one Z-stabilizer syndrome, got {syndrome:?}" + ); + } + + #[test] + fn test_extract_syndromes_repeated_rounds_stable() { + // Two noiseless rounds should both report zero syndrome. + let stabs: Vec> = vec![ + vec![(0, PauliKind::Z), (1, PauliKind::Z)], + vec![(1, PauliKind::Z), (2, PauliKind::Z)], + ]; + let ancillas = vec![QubitId(3), QubitId(4)]; + let mut stn = StabMps::builder(5).seed(42).for_sparse_t().build(); + // Trivial |000⟩ data is already a +1 eigenstate of Z_iZ_j. + for _round in 0..2 { + let s = stn.extract_syndromes(&stabs, &ancillas); + assert_eq!(s, vec![false, false]); + } + } + + #[test] + fn test_inject_paulis_in_frame_bulk() { + let mut stn = StabMps::builder(3) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_paulis_in_frame(&[ + (QubitId(0), PauliKind::X), + (QubitId(1), PauliKind::Y), + (QubitId(2), PauliKind::Z), + ]); + assert!(stn.frame_x_bit(QubitId(0))); + assert!(!stn.frame_z_bit(QubitId(0))); + assert!(stn.frame_x_bit(QubitId(1))); + assert!(stn.frame_z_bit(QubitId(1))); + assert!(!stn.frame_x_bit(QubitId(2))); + assert!(stn.frame_z_bit(QubitId(2))); + } + + #[test] + fn test_pauli_frame_cx_propagates() { + // Inject X on q0, apply CX(0, 1). Frame X propagates: X_0 → X_0·X_1. + let mut stn = StabMps::builder(2) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_x_in_frame(QubitId(0)); + stn.cx(&[(QubitId(0), QubitId(1))]); + assert!(stn.frame_x_bit(QubitId(0))); + assert!( + stn.frame_x_bit(QubitId(1)), + "CX should propagate X to target" + ); + } + + #[test] + fn test_pauli_frame_sz_propagation_phase() { + // SZ · X · SZdg = Y (no sign flip). SZ · Y · SZdg = -X (sign flip). + let mut stn = StabMps::builder(1) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_x_in_frame(QubitId(0)); + stn.sz(&[QubitId(0)]); + // X → Y: bits (1,0) → (1,1), phase stays +1. + assert!(stn.frame_x_bit(QubitId(0))); + assert!(stn.frame_z_bit(QubitId(0))); + assert!( + (stn.pauli_frame_phase - Complex64::new(1.0, 0.0)).norm() < 1e-12, + "SZ on X should not flip phase, got {:?}", + stn.pauli_frame_phase + ); + + // Now apply SZ again: Y → -X. Phase should flip to -1. + stn.sz(&[QubitId(0)]); + assert!(stn.frame_x_bit(QubitId(0))); + assert!(!stn.frame_z_bit(QubitId(0))); + assert!( + (stn.pauli_frame_phase + Complex64::new(1.0, 0.0)).norm() < 1e-12, + "SZ on Y should flip phase to -1, got {:?}", + stn.pauli_frame_phase + ); + } + + #[test] + fn test_pauli_frame_szdg_propagation_phase() { + // SZdg · X · SZ = -Y (sign flip). SZdg · Y · SZ = +X (no sign flip). + let mut stn = StabMps::builder(1) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_x_in_frame(QubitId(0)); + stn.szdg(&[QubitId(0)]); + // X → -Y: bits (1,0) → (1,1), phase -1. + assert!(stn.frame_x_bit(QubitId(0))); + assert!(stn.frame_z_bit(QubitId(0))); + assert!( + (stn.pauli_frame_phase + Complex64::new(1.0, 0.0)).norm() < 1e-12, + "SZdg on X should flip phase to -1, got {:?}", + stn.pauli_frame_phase + ); + + // Apply SZdg again: -Y → +X → -(-X) = +X? No: frame is -Y, bits (1,1). + // SZdg on Y: Y → X, no sign flip. Phase stays -1. + stn.szdg(&[QubitId(0)]); + assert!(stn.frame_x_bit(QubitId(0))); + assert!(!stn.frame_z_bit(QubitId(0))); + assert!( + (stn.pauli_frame_phase + Complex64::new(1.0, 0.0)).norm() < 1e-12, + "SZdg on Y should NOT flip phase, got {:?}", + stn.pauli_frame_phase + ); + } + + #[test] + fn test_pauli_frame_sz_szdg_state_vector_exact() { + // End-to-end: inject X, apply SZ, flush, check state_vector matches + // eager application. Physical: SZ · X · |0⟩ = SZ · |1⟩ = i|1⟩. + // Frame path: state |0⟩, frame = Y (from SZ on X), flush via decomposition. + let mut stn = StabMps::builder(1) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn.inject_x_in_frame(QubitId(0)); + stn.sz(&[QubitId(0)]); + stn.flush_pauli_frame_to_state(); + let sv = stn.state_vector(); + // Expected: SZ·X|0⟩ = SZ|1⟩ = i|1⟩. + assert!(sv[0].norm() < 1e-10, "amp |0⟩: {:?}", sv[0]); + assert!( + (sv[1] - Complex64::new(0.0, 1.0)).norm() < 1e-10, + "amp |1⟩ should be +i, got {:?}", + sv[1] + ); + } + + #[test] + fn test_pauli_frame_cz_propagates() { + // CZ Heisenberg: X_a → X_a Z_b, X_b → Z_a X_b, Z unchanged. + let mut stn = StabMps::builder(2) + .seed(42) + .pauli_frame_tracking(true) + .build(); + // Inject X on q0 only. + stn.inject_x_in_frame(QubitId(0)); + stn.cz(&[(QubitId(0), QubitId(1))]); + // After CZ: X_0 → X_0 Z_1. So q0 still X, q1 gains Z. + assert!(stn.frame_x_bit(QubitId(0)), "CZ: X_0 stays"); + assert!(!stn.frame_x_bit(QubitId(1)), "CZ: q1 should not gain X"); + assert!( + stn.frame_z_bit(QubitId(1)), + "CZ: X_0 → X_0 Z_1, so q1 gains Z" + ); + assert!(!stn.frame_z_bit(QubitId(0)), "CZ: q0 should not gain Z"); + + // Now inject Z on q1 separately, apply CZ(0,1) again. + // Frame is now X_0, Z_1+Z_1=I on q1 (toggled off). So frame = X_0. + // After another CZ: X_0 → X_0 Z_1 again. + let mut stn2 = StabMps::builder(2) + .seed(42) + .pauli_frame_tracking(true) + .build(); + stn2.inject_z_in_frame(QubitId(0)); + stn2.cz(&[(QubitId(0), QubitId(1))]); + // Z_0 → Z_0 (Z commutes with CZ). No change. + assert!(!stn2.frame_x_bit(QubitId(0))); + assert!(stn2.frame_z_bit(QubitId(0)), "CZ: Z_0 unchanged"); + assert!(!stn2.frame_x_bit(QubitId(1))); + assert!( + !stn2.frame_z_bit(QubitId(1)), + "CZ: Z_0 doesn't propagate to q1" + ); + } + + #[test] + fn test_reset_qubit_with_frame_tracking_clears_and_measures_correctly() { + // With frame tracking enabled: inject X error, then reset_qubit. + // The reported outcome from reset should reflect the frame, + // and after reset the qubit should be |0⟩ with no frame bits. + let mut stn = StabMps::builder(1) + .seed(42) + .pauli_frame_tracking(true) + .build(); + // State = |0⟩, frame X = flip → physical is |1⟩. + stn.inject_x_in_frame(QubitId(0)); + let phys = stn.reset_qubit(QubitId(0)); + // Physical outcome should be true (qubit was in |1⟩ physically). + assert!(phys, "reset with X-frame on |0⟩ should report physical |1⟩"); + // Frame cleared. + assert!(!stn.frame_x_bit(QubitId(0)), "frame X must be cleared"); + assert!(!stn.frame_z_bit(QubitId(0)), "frame Z must be cleared"); + // Post-reset measurement should give 0. + let r = stn.mz(&[QubitId(0)]); + assert!(!r[0].outcome, "post-reset mz must be 0"); + + // Now test with Y frame (both X and Z bits). + let mut stn = StabMps::builder(1) + .seed(7) + .pauli_frame_tracking(true) + .build(); + stn.inject_y_in_frame(QubitId(0)); + let _phys = stn.reset_qubit(QubitId(0)); + assert!(!stn.frame_x_bit(QubitId(0))); + assert!(!stn.frame_z_bit(QubitId(0))); + let r = stn.mz(&[QubitId(0)]); + assert!(!r[0].outcome, "post-Y-reset mz must be 0"); + } + + #[test] + fn test_pauli_frame_faster_than_eager_for_many_noise_injects() { + // Timing sanity check: many Pauli injections into frame should + // be far faster than applying each to tableau. + use std::time::Instant; + let n = 32; + let num_injects = 10_000; + + let mut stn_frame = StabMps::builder(n) + .seed(1) + .pauli_frame_tracking(true) + .build(); + let start = Instant::now(); + for _ in 0..num_injects { + stn_frame.apply_depolarizing(QubitId(0), 1.0); + } + let t_frame = start.elapsed().as_secs_f64(); + + let mut stn_eager = StabMps::builder(n).seed(1).build(); + let start = Instant::now(); + for _ in 0..num_injects { + stn_eager.apply_depolarizing(QubitId(0), 1.0); + } + let t_eager = start.elapsed().as_secs_f64(); + + // Frame tracking should be at least 2x faster. + eprintln!( + "Pauli frame: {t_frame:.4}s; eager: {t_eager:.4}s → {:.1}x", + t_eager / t_frame + ); + assert!( + t_frame * 2.0 < t_eager, + "frame tracking should be >2x faster: frame={t_frame:.4}s eager={t_eager:.4}s" + ); + } + + #[test] + fn test_apply_bit_flip_zero_p_noop() { + let mut stn = StabMps::with_seed(2, 42); + // p = 0: no flip, deterministic. + for _ in 0..10 { + assert!(!stn.apply_bit_flip(QubitId(0), 0.0)); + } + let result = stn.mz(&[QubitId(0)])[0].outcome; + assert!(!result, "no-op noise: |0> should give 0"); + } + + #[test] + fn test_apply_bit_flip_p_one_always_flips() { + let mut stn = StabMps::with_seed(2, 42); + // p = 1: always flips. + for _ in 0..5 { + assert!(stn.apply_bit_flip(QubitId(0), 1.0)); + } + // 5 X's = X (odd count) → q0 = 1. + let result = stn.mz(&[QubitId(0)])[0].outcome; + assert!(result, "5x X(0) should leave q0 = 1"); + } + + #[test] + fn test_apply_depolarizing_p_zero_noop() { + let mut stn = StabMps::with_seed(2, 42); + for _ in 0..10 { + assert!(stn.apply_depolarizing(QubitId(0), 0.0).is_none()); + } + // Z-basis measurement of |0> is deterministic. + let results = stn.mz(&[QubitId(0)]); + assert!(results[0].is_deterministic && !results[0].outcome); + } + + #[test] + fn test_apply_depolarizing_distribution() { + // p = 0.9: error occurs ~90% of the time. Of those, X/Y/Z each ~30%. + // For 1000 trials, count outcomes. + let mut x_count = 0; + let mut y_count = 0; + let mut z_count = 0; + let mut none_count = 0; + let trials = 2000; + let mut stn = StabMps::with_seed(1, 42); + for _ in 0..trials { + stn.reset(); + match stn.apply_depolarizing(QubitId(0), 0.9) { + Some(PauliKind::X) => x_count += 1, + Some(PauliKind::Y) => y_count += 1, + Some(PauliKind::Z) => z_count += 1, + None => none_count += 1, + } + } + let frac_none = f64::from(none_count) / f64::from(trials); + let frac_each_pauli = f64::from(x_count + y_count + z_count) / f64::from(trials) / 3.0; + // None = 1 - p ≈ 0.10. Each Pauli ≈ p/3 ≈ 0.30. Tolerance ±5%. + assert!((frac_none - 0.10).abs() < 0.05, "P(no error) = {frac_none}"); + assert!( + (frac_each_pauli - 0.30).abs() < 0.05, + "P(each Pauli) = {frac_each_pauli}" + ); + } + + #[test] + fn test_apply_depolarizing_all_uses_each_qubit() { + // Apply depolarizing to all qubits with p = 1: every qubit gets some error. + let n = 4; + let mut stn = StabMps::with_seed(n, 99); + let qubits: Vec = (0..n).map(QubitId).collect(); + stn.apply_depolarizing_all(&qubits, 1.0); + // After error on each qubit (X, Y, or Z), the state is no longer |0^N>. + // For Z errors only, qubit stays in |0> (Z|0>=|0>). For X/Y, q flips to |1>. + // At least some qubits should have flipped (very high prob with 4 qubits). + let outcomes: Vec = stn.mz(&qubits).iter().map(|r| r.outcome).collect(); + let any_flipped = outcomes.iter().any(|&b| b); + assert!( + any_flipped, + "with p=1 on 4 qubits, at least one X/Y likely; got {outcomes:?}" + ); + } + + #[test] + fn test_pauli_expectation_n_30_zz_chain() { + // 30-qubit GHZ-like state, scales beyond the SV path's n<=14 limit. + // After H(0) + CX chain, ZZ on neighboring qubits = 1 (Bell-style). + let n = 30; + let mut stn = StabMps::new(n); + stn.h(&[QubitId(0)]); + for q in 0..n - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + // ⟨ZZ_{0,1}⟩ on GHZ = 1. + let zz01 = stn.pauli_expectation(&[(0, PauliKind::Z), (1, PauliKind::Z)]); + assert!((zz01 - 1.0).abs() < 1e-10, "n=30 ZZ_{{0,1}}: {zz01}"); + // ⟨ZZ_{15,29}⟩ on GHZ = 1 (long-range still correlated). + let zz_far = stn.pauli_expectation(&[(15, PauliKind::Z), (29, PauliKind::Z)]); + assert!((zz_far - 1.0).abs() < 1e-10, "n=30 ZZ_{{15,29}}: {zz_far}"); + } + + #[test] + fn test_pauli_expectation_zz_on_bell_state() { + // Bell state (|00⟩+|11⟩)/√2: ⟨ZZ⟩ = 1, ⟨XX⟩ = 1, ⟨YY⟩ = -1. + let mut stn = StabMps::new(2); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + let zz = stn.pauli_expectation(&[(0, PauliKind::Z), (1, PauliKind::Z)]); + let xx = stn.pauli_expectation(&[(0, PauliKind::X), (1, PauliKind::X)]); + let yy = stn.pauli_expectation(&[(0, PauliKind::Y), (1, PauliKind::Y)]); + assert!((zz - 1.0).abs() < 1e-10, "ZZ on Bell = {zz}"); + assert!((xx - 1.0).abs() < 1e-10, "XX on Bell = {xx}"); + assert!((yy + 1.0).abs() < 1e-10, "YY on Bell = {yy}"); + } + + #[test] + fn test_overlap_with_stabilizer_matches_state_vector() { + // |s⟩ = |+⟩|0⟩|+⟩ via H on qubits 0 and 2. + // |Ψ⟩ = |+⟩|0⟩|+⟩ same → overlap = 1. + use pecos_simulators::CHForm; + let mut s = CHForm::new_with_seed(3, 42); + s.h(&[QubitId(0), QubitId(2)]); + + let mut stn = StabMps::with_seed(3, 99); + stn.h(&[QubitId(0), QubitId(2)]); + + let est = stn.overlap_with_stabilizer(&s, 200, None); + // Should be ~1 with some MC noise. For identical pure states, + // each sample contributes exactly 1, so accumulator = num_samples + // and average = 1 exactly (no variance for identical states). + assert!( + (est.norm_sqr() - 1.0).abs() < 0.01, + "identical states fidelity should be 1.0, got |est|² = {}", + est.norm_sqr() + ); + } + + #[test] + fn test_overlap_with_stabilizer_orthogonal_zero() { + // |s⟩ = |0⟩, |Ψ⟩ = |1⟩ → overlap = 0. + use pecos_simulators::CHForm; + let s = CHForm::new_with_seed(2, 7); + // |s⟩ = |00⟩. + + let mut stn = StabMps::with_seed(2, 99); + stn.x(&[QubitId(0)]); // |Ψ⟩ = |10⟩. + + // |s⟩ has support {|00⟩} only, so MC samples always give x=|00⟩. + // = <00|10> = 0. Estimator returns 0. + let est = stn.overlap_with_stabilizer(&s, 50, None); + assert!( + est.norm() < 1e-10, + "orthogonal states overlap should be 0, got {}", + est.norm() + ); + } + + #[test] + fn test_code_state_fidelity_three_qubit_bit_flip() { + // 3-qubit bit-flip code |0_L⟩ = |000⟩, |1_L⟩ = |111⟩. + // Stabilizers: Z_0·Z_1, Z_1·Z_2. + // Logical |0_L⟩ = |000⟩ is in the code → fidelity = 1. + let mut stn = StabMps::new(3); + // |000⟩ initially. + let stabs = vec![ + vec![(0, PauliKind::Z), (1, PauliKind::Z)], + vec![(1, PauliKind::Z), (2, PauliKind::Z)], + ]; + let f = stn.code_state_fidelity(&stabs); + assert!( + (f - 1.0).abs() < 1e-10, + "|000⟩ in bit-flip code, fidelity {f}" + ); + + // Apply X_0 → |100⟩, an error state, NOT in the code. + // Z_0·Z_1·|100⟩ = -|100⟩ (Z_0 gives -1), so it's a -1 eigenstate of stab → fidelity = 0. + stn.x(&[QubitId(0)]); + let f = stn.code_state_fidelity(&stabs); + assert!(f.abs() < 1e-10, "|100⟩ NOT in bit-flip code, fidelity {f}"); + + // Encode logical |1⟩: |111⟩ via X on all 3. + stn.reset(); + stn.x(&[QubitId(0), QubitId(1), QubitId(2)]); + let f = stn.code_state_fidelity(&stabs); + assert!( + (f - 1.0).abs() < 1e-10, + "|111⟩ in bit-flip code, fidelity {f}" + ); + } + + #[test] + fn test_code_state_fidelity_large_n_repetition_code() { + // 8-qubit repetition code (logical 0 = |00000000>): stabilizers are + // Z_iZ_{i+1} for i in 0..7. After preparing |0^N>, fidelity = 1. + let n = 8; + let stabs: Vec> = (0..n - 1) + .map(|i| vec![(i, PauliKind::Z), (i + 1, PauliKind::Z)]) + .collect(); + let stn = StabMps::new(n); + let f = stn.code_state_fidelity(&stabs); + assert!((f - 1.0).abs() < 1e-10, "n=8 |0..0> rep code fidelity {f}"); + } + + #[test] + fn test_code_state_fidelity_partial() { + // Superposition partly in / partly out of code. + // 50/50 mix of |000⟩ (in code) and |001⟩ (out of code) → fidelity = 0.5. + let mut stn = StabMps::new(3); + stn.h(&[QubitId(2)]); // |0⟩|0⟩(|0⟩+|1⟩)/√2 = (|000⟩ + |001⟩)/√2 + let stabs = vec![ + vec![(0, PauliKind::Z), (1, PauliKind::Z)], + vec![(1, PauliKind::Z), (2, PauliKind::Z)], + ]; + let f = stn.code_state_fidelity(&stabs); + assert!((f - 0.5).abs() < 1e-10, "half/half, fidelity {f}"); + } + + #[test] + fn test_merge_rz_commutes_through_z_and_s() { + // RZ(t, q); Z(q); RZ(t, q); S(q); RZ(t, q) should merge to one + // non-Clifford at flush time, because Z and S commute with RZ. + // Compare vs eager (no commute optimization, same physics). + let t = Angle64::from_radians(0.12345); + + let mut merged = StabMps::builder(2).seed(7).merge_rz(true).build(); + merged.h(&[QubitId(0)]); // make MPS non-trivial + merged.rz(t, &[QubitId(0)]); + merged.z(&[QubitId(0)]); + merged.rz(t, &[QubitId(0)]); + merged.sz(&[QubitId(0)]); + merged.rz(t, &[QubitId(0)]); + merged.flush(); + let sv_merged = merged.state_vector(); + let nc_merged = merged.stats.total_nonclifford; + + let mut eager = StabMps::with_seed(2, 7); + eager.h(&[QubitId(0)]); + eager.rz(t, &[QubitId(0)]); + eager.z(&[QubitId(0)]); + eager.rz(t, &[QubitId(0)]); + eager.sz(&[QubitId(0)]); + eager.rz(t, &[QubitId(0)]); + let sv_eager = eager.state_vector(); + + for (a, b) in sv_eager.iter().zip(sv_merged.iter()) { + assert!((a - b).norm() < 1e-10, "commute-merge state mismatch"); + } + // Merge saves non-Clifford applications: 3 → 1. + assert_eq!( + nc_merged, 1, + "merged should call non-Clifford path once; got {nc_merged}" + ); + assert_eq!( + eager.stats.total_nonclifford, 3, + "eager applies 3 non-Cliffords" + ); + } + + #[test] + fn test_merge_rz_x_flips_pending_sign() { + // X anticommutes with RZ. rz(t, q); x(q) should leave pending_rz + // = -t. Final state after x(q) + rz(t, q) + flush should equal + // applying x then rz(t) (since net = identity for +t−t... wait + // actually: X·RZ(θ) = RZ(-θ)·X. So rz(t); x; rz(t) = x; rz(-t); rz(t) = x. + // Verify equality with just x applied. + let t = Angle64::from_radians(0.7); + + let mut merged = StabMps::builder(2).seed(5).merge_rz(true).build(); + merged.h(&[QubitId(0)]); // non-trivial MPS + merged.rz(t, &[QubitId(0)]); + merged.x(&[QubitId(0)]); + merged.rz(t, &[QubitId(0)]); + merged.flush(); + let sv_merged = merged.state_vector(); + + // Reference: just H and X (since RZ effects cancel via X-flip). + let mut ref_sim = StabMps::with_seed(2, 5); + ref_sim.h(&[QubitId(0)]); + ref_sim.x(&[QubitId(0)]); + let sv_ref = ref_sim.state_vector(); + + for (a, b) in sv_ref.iter().zip(sv_merged.iter()) { + assert!( + (a - b).norm() < 1e-10, + "X-flip pending-rz sign mismatch: {a} vs {b}" + ); + } + } + + #[test] + fn test_merge_rz_two_t_gates_same_state_vector() { + // RZ(t) + RZ(t) merged should equal one RZ(2t) and equal eager + // applying RZ(t) twice. Compare state vectors. + let t = Angle64::QUARTER_TURN / 2u64; // T + + let mut eager = StabMps::with_seed(2, 7); + eager.h(&[QubitId(0)]); + eager.cx(&[(QubitId(0), QubitId(1))]); + eager.rz(t, &[QubitId(0)]); + eager.rz(t, &[QubitId(0)]); + let sv_eager = eager.state_vector(); + + let mut merged = StabMps::builder(2).seed(7).merge_rz(true).build(); + merged.h(&[QubitId(0)]); + merged.cx(&[(QubitId(0), QubitId(1))]); + merged.rz(t, &[QubitId(0)]); + merged.rz(t, &[QubitId(0)]); + merged.flush(); + let sv_merged = merged.state_vector(); + + for (a, b) in sv_eager.iter().zip(sv_merged.iter()) { + assert!((a - b).norm() < 1e-10, "merge_rz state mismatch"); + } + } + + #[test] + fn test_merge_rz_intervening_gate_on_other_qubit_still_merges() { + // rz(t, 0); h(1); rz(t, 0) — h(1) does not touch q0, so merge applies. + let t = Angle64::QUARTER_TURN / 2u64; + + let mut merged = StabMps::builder(2).seed(11).merge_rz(true).build(); + merged.h(&[QubitId(0)]); + merged.rz(t, &[QubitId(0)]); + merged.h(&[QubitId(1)]); + merged.rz(t, &[QubitId(0)]); + merged.flush(); + let sv_merged = merged.state_vector(); + + let mut eager = StabMps::with_seed(2, 11); + eager.h(&[QubitId(0)]); + eager.rz(t, &[QubitId(0)]); + eager.h(&[QubitId(1)]); + eager.rz(t, &[QubitId(0)]); + let sv_eager = eager.state_vector(); + + for (a, b) in sv_eager.iter().zip(sv_merged.iter()) { + assert!( + (a - b).norm() < 1e-10, + "intervening other-qubit gate merge mismatch" + ); + } + } + + #[test] + fn test_merge_rz_intervening_gate_on_same_qubit_flushes() { + // rz(t, 0); h(0); rz(t, 0) — h(0) flushes pending rz first. + let t = Angle64::QUARTER_TURN / 2u64; + + let mut merged = StabMps::builder(2).seed(13).merge_rz(true).build(); + merged.h(&[QubitId(0)]); + merged.rz(t, &[QubitId(0)]); + merged.h(&[QubitId(0)]); + merged.rz(t, &[QubitId(0)]); + merged.flush(); + let sv_merged = merged.state_vector(); + + let mut eager = StabMps::with_seed(2, 13); + eager.h(&[QubitId(0)]); + eager.rz(t, &[QubitId(0)]); + eager.h(&[QubitId(0)]); + eager.rz(t, &[QubitId(0)]); + let sv_eager = eager.state_vector(); + + for (a, b) in sv_eager.iter().zip(sv_merged.iter()) { + assert!( + (a - b).norm() < 1e-10, + "intervening same-qubit gate flush mismatch" + ); + } + } + + #[test] + fn test_merge_rz_to_clifford_angle_uses_fast_path() { + // Two T gates merge to S (RZ(π/2)) — Clifford angle, taken via tableau. + let t = Angle64::QUARTER_TURN / 2u64; + + let mut merged = StabMps::builder(2).seed(17).merge_rz(true).build(); + merged.h(&[QubitId(0)]); + merged.rz(t, &[QubitId(0)]); + merged.rz(t, &[QubitId(0)]); + merged.flush(); + // After merge, no pending RZ, no MPS non-Clifford gate count incremented. + assert_eq!( + merged.stats.total_nonclifford, 0, + "two T merging to S should hit Clifford fast path, not non-Clifford" + ); + + let mut eager = StabMps::with_seed(2, 17); + eager.h(&[QubitId(0)]); + eager.rz(t, &[QubitId(0)]); + eager.rz(t, &[QubitId(0)]); + // Eager applies T twice as non-Clifford. + assert_eq!(eager.stats.total_nonclifford, 2); + + // Both produce equivalent state. + let sv_merged = merged.state_vector(); + let sv_eager = eager.state_vector(); + for (a, b) in sv_eager.iter().zip(sv_merged.iter()) { + assert!((a - b).norm() < 1e-10, "T+T = S state mismatch"); + } + } + + #[test] + fn test_builder_for_sparse_t_preset() { + // Smoke test: the preset should build a working StabMps and handle + // a Clifford + T + measurement sequence. + let mut stn = StabMps::builder(4).seed(99).for_sparse_t().build(); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(2)]); + let r0 = stn.mz(&[QubitId(0)])[0].outcome; + let r1 = stn.mz(&[QubitId(1)])[0].outcome; + assert_eq!(r0, r1, "for_sparse_t preset: Bell+T correlation"); + } + + #[test] + fn test_builder_lazy_measure_bell_correlation() { + // Lazy-measure path must give same Bell-state correlation as eager. + for trial in 0..20 { + let mut stn = StabMps::builder(2) + .seed(3000 + trial) + .lazy_measure(true) + .build(); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let r0 = stn.mz(&[QubitId(0)])[0].outcome; + let r1 = stn.mz(&[QubitId(1)])[0].outcome; + assert_eq!(r0, r1, "lazy Bell+T trial {trial}"); + } + } + + #[test] + fn test_builder_lazy_measure_rx_statistics() { + // Lazy path must give correct RX(pi/3) measurement statistics. + let theta = Angle64::from_radians(std::f64::consts::FRAC_PI_3); + let num_trials: u32 = 400; + let mut count_0 = 0; + for trial in 0..num_trials { + let mut stn = StabMps::builder(1) + .seed(u64::from(4000 + trial)) + .lazy_measure(true) + .build(); + stn.rx(theta, &[QubitId(0)]); + if !stn.mz(&[QubitId(0)])[0].outcome { + count_0 += 1; + } + } + let p0 = f64::from(count_0) / f64::from(num_trials); + assert!((p0 - 0.75).abs() < 0.08, "lazy RX(pi/3) p(0) = {p0:.3}"); + } +} diff --git a/exp/pecos-stab-tn/src/stab_mps/compile.rs b/exp/pecos-stab-tn/src/stab_mps/compile.rs new file mode 100644 index 000000000..81602231e --- /dev/null +++ b/exp/pecos-stab-tn/src/stab_mps/compile.rs @@ -0,0 +1,435 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Compile-only pre-analysis for STN tractability. +//! +//! Runs through a circuit's Clifford tableau and non-Clifford gate decomposition +//! WITHOUT building an MPS. Reports the GF(2) nullity of the accumulated flip +//! patterns, which per Liu-Clark 2412.17209 bounds the CAMPS bond dimension: +//! `bond_dim` ≤ 2^nullity. +//! +//! Useful for deciding whether a circuit is tractable for full simulation +//! before committing resources. Complexity is O(t·n²) for t non-Cliffords +//! and n qubits (Clifford tableau ops dominate). + +use super::ofd::{Gf2FlipMatrix, RowMetadata}; +use super::pauli_decomp::{ZDecomposition, decompose_z}; +use pecos_core::{Angle64, QubitId}; +use pecos_simulators::{ + ArbitraryRotationGateable, CliffordGateable, MeasurementResult, QuantumSimulator, SparseStabY, +}; + +/// Compile-only STN analyzer: runs Clifford tableau and tracks OFD-relevant +/// GF(2) flip patterns, without any MPS representation. +pub struct StabMpsCompile { + num_qubits: usize, + tableau: SparseStabY, + gf2_matrix: Gf2FlipMatrix, + /// Per-site "free qubit" flag: true if this qubit has never been the + /// disent `rot_site`. Mirrors our `disent_flags` for OFD applicability. + free_qubit: Vec, + /// Number of non-Clifford gates that OFD would absorb (consume a free qubit). + absorbed: u64, + /// Number of non-Clifford gates that would grow bond dim. + grown: u64, + /// Number of non-Cliffords that hit the Stabilizer branch (no MPS site op). + stabilizer: u64, +} + +impl StabMpsCompile { + #[must_use] + pub fn new(num_qubits: usize) -> Self { + Self { + num_qubits, + tableau: SparseStabY::new(num_qubits).with_destab_sign_tracking(), + gf2_matrix: Gf2FlipMatrix::new(num_qubits), + free_qubit: vec![true; num_qubits], + absorbed: 0, + grown: 0, + stabilizer: 0, + } + } + + #[must_use] + pub fn num_qubits(&self) -> usize { + self.num_qubits + } + + /// Number of non-Clifford gates that consumed a free qubit (disentangled). + #[must_use] + pub fn absorbed(&self) -> u64 { + self.absorbed + } + + /// Number of non-Clifford gates that would grow bond dim. + #[must_use] + pub fn grown(&self) -> u64 { + self.grown + } + + /// Number of non-Cliffords that hit the Stabilizer branch. + #[must_use] + pub fn stabilizer(&self) -> u64 { + self.stabilizer + } + + /// Total non-Clifford gates processed. + #[must_use] + pub fn total_nonclifford(&self) -> u64 { + self.absorbed + self.grown + self.stabilizer + } + + /// GF(2) nullity = number of flip patterns NOT in the rank. + /// Bond dim bound from OFD is 2^nullity. + #[must_use] + pub fn nullity(&self) -> usize { + let t = self.gf2_matrix.num_gates(); + t.saturating_sub(self.gf2_matrix.gf2_rank()) + } + + /// Rank of accumulated GF(2) matrix. + #[must_use] + pub fn rank(&self) -> usize { + self.gf2_matrix.gf2_rank() + } + + /// Theoretical bond dim upper bound: 2^nullity. + #[must_use] + pub fn bond_dim_bound(&self) -> usize { + let n = self.nullity(); + if n == 0 { + 1 + } else { + 1usize + .checked_shl(u32::try_from(n).unwrap_or(u32::MAX)) + .unwrap_or(usize::MAX) + } + } + + /// Access the accumulated GF(2) matrix for inspection. + #[must_use] + pub fn gf2_matrix(&self) -> &Gf2FlipMatrix { + &self.gf2_matrix + } + + /// Recommend which PECOS simulator best fits the accumulated circuit + /// characteristics. Based on a heuristic cost model — see the + /// `SimulatorRecommendation` docstring for exact decision rules. + /// + /// Use case: after running a circuit through `StabMpsCompile` (which does + /// O(t·n²) pre-analysis without any MPS overhead), dispatch to the + /// best simulator for actual simulation. + #[must_use] + pub fn recommend(&self) -> SimulatorRecommendation { + let n = self.num_qubits(); + let t = self.total_nonclifford(); + let nullity = self.nullity(); + + // Pure Clifford: CHForm is exact and fastest. + if t == 0 { + return SimulatorRecommendation { + kind: SimulatorKind::CHForm, + reason: "pure Clifford circuit — CHForm is exact and O(n²) memory".to_string(), + }; + } + // Small n: dense state vector is straightforward and fastest. + if n <= 14 { + return SimulatorRecommendation { + kind: SimulatorKind::StateVector, + reason: format!("small system (n={n} ≤ 14) — dense state vector fits in memory"), + }; + } + // Low-rank: STN bond dim bound is 2^nullity; stays cheap at small nullity. + if nullity <= 6 { + return SimulatorRecommendation { + kind: SimulatorKind::StabMps, + reason: format!( + "low OFD nullity ({nullity}) — STN bond dim bound 2^{nullity} = {}", + 1usize << nullity + ), + }; + } + // Moderate T-count: StabVec stabilizer-sum with pruning. + if t <= 40 { + return SimulatorRecommendation { + kind: SimulatorKind::StabVec, + reason: format!("moderate T-count (t={t} ≤ 40) — StabVec with MC pruning"), + }; + } + // Fallback: STN with adaptive bond-dim cap. + SimulatorRecommendation { + kind: SimulatorKind::StabMps, + reason: format!( + "large nullity (nullity={nullity}) and high T-count (t={t}) — \ + STN with auto_grow_bond_dim recommended" + ), + } + } + + /// Process one non-Clifford Z-rotation on qubit q. Mirrors the decision + /// logic of `non_clifford::apply_rz_stab_mps` but does not modify any MPS. + fn process_rz(&mut self, q: usize) { + let decomp = decompose_z(self.tableau.stabs(), self.tableau.destabs(), q); + match decomp { + ZDecomposition::Stabilizer { .. } => { + self.stabilizer += 1; + } + ZDecomposition::DestabilizerFlip { + ref flip_sites, + ref sign_sites, + .. + } => { + // Build list of affected sites (union of flip + sign). + let mut sites: std::collections::BTreeSet = + std::collections::BTreeSet::new(); + for s in flip_sites { + sites.insert(*s); + } + for s in sign_sites { + sites.insert(*s); + } + let affected: Vec = sites.into_iter().collect(); + + if affected.len() == 1 { + // Single-site path: always absorbable. + let site = affected[0]; + self.absorbed += 1; + let flip_vec: Vec = flip_sites.clone(); + self.gf2_matrix + .add_row_with_meta(&flip_vec, RowMetadata { rot_site: site }); + self.free_qubit[site] = false; + } else { + // Multi-site: OFD condition is "some site i has free_qubit[i] + // AND site i has X/Y pauli (i.e. i ∈ flip_sites)". + let mut rot = None; + for &s in &affected { + if self.free_qubit[s] && flip_sites.contains(&s) { + rot = Some(s); + break; + } + } + if let Some(site) = rot { + self.absorbed += 1; + let flip_vec: Vec = flip_sites.clone(); + self.gf2_matrix + .add_row_with_meta(&flip_vec, RowMetadata { rot_site: site }); + self.free_qubit[site] = false; + } else { + self.grown += 1; + } + } + } + } + } +} + +/// Classification of PECOS simulators for dispatch purposes. +/// See `StabMpsCompile::recommend`. +#[derive(Clone, Copy, Debug, PartialEq, Eq)] +pub enum SimulatorKind { + /// Dense state vector (e.g., `pecos_simulators::StateVec`). Exact; + /// O(2^n) memory. Best for small n. + StateVector, + /// CH-form stabilizer simulator + /// (`pecos_simulators::CHForm`). Exact for pure Clifford; O(n²) memory. + CHForm, + /// Clifford+Rz stabilizer-sum simulator + /// (`pecos_simulators::StabVec`). Stabilizer-rank method with + /// MC pruning. Best for moderate T-count. + StabVec, + /// Stabilizer Tensor Network + /// (`pecos_stab_tn::stab_mps::StabMps`). Hybrid tableau+MPS. Best for + /// low-rank (low OFD nullity) circuits and T-heavy circuits with + /// adaptive bond-dim. + StabMps, +} + +/// Simulator recommendation with a human-readable reason string. +/// Returned by `StabMpsCompile::recommend`. +#[derive(Clone, Debug)] +pub struct SimulatorRecommendation { + pub kind: SimulatorKind, + pub reason: String, +} + +impl QuantumSimulator for StabMpsCompile { + fn reset(&mut self) -> &mut Self { + self.tableau = SparseStabY::new(self.num_qubits).with_destab_sign_tracking(); + self.gf2_matrix.reset(); + self.free_qubit = vec![true; self.num_qubits]; + self.absorbed = 0; + self.grown = 0; + self.stabilizer = 0; + self + } + + fn num_qubits(&self) -> usize { + self.num_qubits + } +} + +impl CliffordGateable for StabMpsCompile { + fn sz(&mut self, qubits: &[QubitId]) -> &mut Self { + self.tableau.sz(qubits); + self + } + fn h(&mut self, qubits: &[QubitId]) -> &mut Self { + self.tableau.h(qubits); + self + } + fn cx(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + self.tableau.cx(pairs); + self + } + fn cz(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + self.tableau.cz(pairs); + self + } + fn mz(&mut self, qubits: &[QubitId]) -> Vec { + // Compile mode: delegate to tableau (no MPS needed for measurement). + self.tableau.mz(qubits) + } +} + +impl ArbitraryRotationGateable for StabMpsCompile { + fn rx(&mut self, theta: Angle64, qubits: &[QubitId]) -> &mut Self { + self.h(qubits); + self.rz(theta, qubits); + self.h(qubits); + self + } + + fn rz(&mut self, theta: Angle64, qubits: &[QubitId]) -> &mut Self { + for &q in qubits { + // Handle Clifford angles as Cliffords. + if theta == Angle64::ZERO { + continue; + } + if theta == Angle64::HALF_TURN { + self.tableau.z(&[q]); + continue; + } + if theta == Angle64::QUARTER_TURN { + self.tableau.sz(&[q]); + continue; + } + if theta == Angle64::THREE_QUARTERS_TURN { + self.tableau.szdg(&[q]); + continue; + } + // Non-Clifford: process decomposition. + self.process_rz(q.index()); + } + self + } + + fn rzz(&mut self, theta: Angle64, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q0, q1) in pairs { + self.cx(&[(q0, q1)]); + self.rz(theta, &[q1]); + self.cx(&[(q0, q1)]); + } + self + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_compile_sizes() { + let s = StabMpsCompile::new(5); + assert_eq!(s.num_qubits(), 5); + assert_eq!(s.nullity(), 0); + assert_eq!(s.bond_dim_bound(), 1); + } + + #[test] + fn test_compile_all_independent_t_gates() { + let mut s = StabMpsCompile::new(5); + s.h(&[QubitId(0), QubitId(1), QubitId(2), QubitId(3), QubitId(4)]); + for i in 0..5 { + s.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(i)]); + } + assert_eq!(s.absorbed(), 5); + assert_eq!(s.grown(), 0); + assert_eq!(s.nullity(), 0); + assert_eq!(s.bond_dim_bound(), 1); + } + + #[test] + fn test_compile_vs_stn_nullity_matches() { + // Verify that StabMpsCompile and full StabMps agree on nullity for same circuit. + use crate::stab_mps::StabMps; + let q = |i: usize| QubitId(i); + let mut comp = StabMpsCompile::new(4); + comp.h(&[q(0), q(1), q(2), q(3)]); + comp.rz(Angle64::QUARTER_TURN / 2u64, &[q(0)]); + comp.cx(&[(q(0), q(1))]); + comp.rz(Angle64::QUARTER_TURN / 2u64, &[q(1)]); + comp.rz(Angle64::QUARTER_TURN / 2u64, &[q(2)]); + + let mut stn = StabMps::with_seed(4, 1); + stn.h(&[q(0), q(1), q(2), q(3)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(0)]); + stn.cx(&[(q(0), q(1))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(1)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q(2)]); + + assert_eq!( + comp.nullity(), + stn.ofd_nullity(), + "StabMpsCompile and StabMps should report same OFD nullity" + ); + } + + #[test] + fn test_recommend_pure_clifford_prefers_chform() { + let mut comp = StabMpsCompile::new(4); + comp.h(&[QubitId(0), QubitId(1)]); + comp.cx(&[(QubitId(0), QubitId(1))]); + // t = 0. + let r = comp.recommend(); + assert_eq!(r.kind, SimulatorKind::CHForm); + } + + #[test] + fn test_recommend_small_n_prefers_state_vector() { + let mut comp = StabMpsCompile::new(8); + comp.h(&[QubitId(0)]); + comp.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); // one T + let r = comp.recommend(); + assert_eq!(r.kind, SimulatorKind::StateVector); + } + + #[test] + fn test_recommend_low_nullity_prefers_stn() { + let n = 20; + let mut comp = StabMpsCompile::new(n); + // Simple Clifford + independent T gates (nullity = 0 because + // same flip pattern on unique qubits each rank-1). + // H on qubit 0, T on qubit 0 gives one flip pattern of weight 1. + // Multiple independent Ts → independent flip patterns → all rank, + // zero nullity. + comp.h(&[QubitId(0)]); + comp.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let r = comp.recommend(); + assert_eq!( + r.kind, + SimulatorKind::StabMps, + "nullity={} should recommend STN for n={n} (reason: {})", + comp.nullity(), + r.reason + ); + } +} diff --git a/exp/pecos-stab-tn/src/stab_mps/disentangle.rs b/exp/pecos-stab-tn/src/stab_mps/disentangle.rs new file mode 100644 index 000000000..86f2acaa8 --- /dev/null +++ b/exp/pecos-stab-tn/src/stab_mps/disentangle.rs @@ -0,0 +1,335 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Heuristic Clifford disentangling for the STN simulator. +//! +//! After non-Clifford gates increase the MPS bond dimension, we can try to +//! reduce it by applying two-qubit Clifford gates that absorb entanglement +//! into the stabilizer tableau. +//! +//! The algorithm: for each internal bond, try the 20 inequivalent entangling +//! two-qubit Cliffords. If one reduces the entanglement entropy at the bond, +//! apply it to the MPS and store the inverse for `state_vector` reconstruction. +//! +//! References: +//! - Masot-Llima, Garcia-Saez. arXiv:2403.08724 (Clifford disentangling). +//! - Masot-Llima, Sierant, Stornati, Garcia-Saez. arXiv:2602.15942 +//! (limits of Clifford disentangling). + +use crate::mps::Mps; +use nalgebra::DMatrix; +use num_complex::Complex64; + +/// A two-qubit Clifford gate for disentangling. +struct DisentanglerGate { + /// 4x4 unitary matrix for the MPS + matrix: DMatrix, + /// 4x4 inverse matrix (for `state_vector` correction) + inverse_matrix: DMatrix, +} + +/// Build a 2x2 single-qubit Clifford gate. +fn single_qubit_clifford(idx: usize) -> DMatrix { + let one = Complex64::new(1.0, 0.0); + let zero = Complex64::new(0.0, 0.0); + let inv2 = Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0); + let i_val = Complex64::new(0.0, 1.0); + + let id = DMatrix::from_row_slice(2, 2, &[one, zero, zero, one]); + let h = DMatrix::from_row_slice(2, 2, &[inv2, inv2, inv2, -inv2]); + let s = DMatrix::from_row_slice(2, 2, &[one, zero, zero, i_val]); + + match idx { + 1 => h.clone(), // H + 2 => s.clone(), // S + 3 => &s * &h, // SH + 4 => &h * &s, // HS + 5 => &h * &s * &h, // HSH + _ => id, // I (idx == 0 or out of range) + } +} + +/// Build the set of candidate disentangling gates. +/// +/// Generates entangling 2-qubit Cliffords by dressing CX with single-qubit +/// Cliffords on each qubit: (A⊗B) * CX * (C⊗D) for various A,B,C,D. +fn build_disentangler_set() -> Vec { + let one = Complex64::new(1.0, 0.0); + let zero = Complex64::new(0.0, 0.0); + + // Base CX gate + let cx = DMatrix::from_row_slice( + 4, + 4, + &[ + one, zero, zero, zero, zero, one, zero, zero, zero, zero, zero, one, zero, zero, one, + zero, + ], + ); + + // Generate dressed CX gates: (A⊗B) * CX for single-qubit Cliffords A, B. + // This covers the 20 inequivalent entangling 2-qubit Cliffords. + // We use 6 single-qubit Cliffords: {I, H, S, SH, HS, HSH} + let mut gates = Vec::new(); + let mut seen = Vec::new(); + + // Dressings: (left_q0, left_q1) applied AFTER CX + let dressings: &[(usize, usize)] = &[ + (0, 0), // I⊗I * CX = CX + (0, 1), // I⊗H * CX + (1, 0), // H⊗I * CX + (1, 1), // H⊗H * CX + (0, 2), // I⊗S * CX + (2, 0), // S⊗I * CX + (3, 0), // SH⊗I * CX + (0, 3), // I⊗SH * CX + (4, 0), // HS⊗I * CX + (0, 4), // I⊗HS * CX + (1, 2), // H⊗S * CX + (2, 1), // S⊗H * CX + (5, 0), // HSH⊗I * CX + (0, 5), // I⊗HSH * CX + (3, 1), // SH⊗H * CX + (1, 3), // H⊗SH * CX + (4, 1), // HS⊗H * CX + (1, 4), // H⊗HS * CX + (2, 2), // S⊗S * CX + (3, 3), // SH⊗SH * CX + ]; + + for &(a_idx, b_idx) in dressings { + let a = single_qubit_clifford(a_idx); + let b = single_qubit_clifford(b_idx); + + // Build A⊗B + let ab = a.kronecker(&b); + let matrix = &ab * &cx; + + // Check for duplicates (up to global phase) + let is_dup = seen.iter().any(|existing: &DMatrix| { + // Two unitaries are equivalent if one is a scalar multiple of the other + if let Some(&first_nonzero) = matrix.iter().zip(existing.iter()).find_map(|(a, b)| { + if a.norm() > 0.1 && b.norm() > 0.1 { + Some(a) + } else { + None + } + }) { + let first_existing = existing + .iter() + .zip(matrix.iter()) + .find_map(|(b, a)| if a.norm() > 0.1 { Some(b) } else { None }); + if let Some(&fe) = first_existing { + let ratio = first_nonzero / fe; + // Check all elements have the same ratio + matrix + .iter() + .zip(existing.iter()) + .all(|(a, b)| (a - b * ratio).norm() < 1e-10) + } else { + false + } + } else { + false + } + }); + + if !is_dup { + seen.push(matrix.clone()); + gates.push(DisentanglerGate { + inverse_matrix: matrix.adjoint(), + matrix, + }); + } + } + + gates +} + +/// Compute the entanglement entropy at a given bond of the MPS. +/// +/// Uses singular values from the bond matrix after left-canonicalization up to that bond. +/// For efficiency, just compute the Frobenius norm ratio as a proxy. +fn bond_entropy(mps: &Mps, bond: usize) -> f64 { + if bond == 0 || bond >= mps.num_sites() { + return 0.0; + } + + let d = mps.phys_dim(); + let chi_l = mps.bond_dim(bond); + let chi_r = mps.bond_dim(bond + 1); + let tensor = &mps.tensors()[bond]; + + // Reshape to (chi_l * d, chi_r) and compute SVD + let matrix = crate::mps::tensor::reshape_left_group(tensor, chi_l, d, chi_r); + let svd = nalgebra::SVD::new(matrix, false, false); + + // Compute von Neumann entropy from singular values + let svals = &svd.singular_values; + let norm_sq: f64 = svals.iter().map(|s| s * s).sum(); + if norm_sq < 1e-30 { + return 0.0; + } + + let mut entropy = 0.0; + for &s in svals.iter() { + let p = (s * s) / norm_sq; + if p > 1e-15 { + entropy -= p * p.ln(); + } + } + entropy +} + +/// Run one sweep of heuristic disentangling on the MPS. +/// +/// For each internal bond, tries each candidate Clifford gate and keeps +/// the one that reduces the max bond dimension of the MPS. Uses max bond +/// dim as the criterion (not local entropy) because a gate that reduces +/// entropy at one bond can increase it at neighboring bonds. +/// +/// Records inverse operations in the gate log so `state_vector()` stays correct. +/// +/// Returns the number of gates applied (0 means no improvement found). +pub(crate) fn disentangle_sweep( + mps: &mut Mps, + corrections: &mut Vec, +) -> usize { + let n = mps.num_sites(); + if n < 2 { + return 0; + } + + let gates = build_disentangler_set(); + let mut num_applied = 0; + + // Forward sweep: bonds 0..n-2 (between sites q and q+1) + for q in 0..n - 1 { + let bond = q + 1; + let current_entropy = bond_entropy(mps, bond); + + if current_entropy < 1e-6 { + continue; // Already effectively disentangled at this bond + } + + let current_max_bond = mps.max_bond_dim(); + let mut best_entropy = current_entropy; + let mut best_gate_idx: Option = None; + + for (gate_idx, gate) in gates.iter().enumerate() { + let mut trial_mps = mps.clone(); + if trial_mps.apply_two_site_gate(q, &gate.matrix).is_ok() { + let trial_max_bond = trial_mps.max_bond_dim(); + let trial_entropy = bond_entropy(&trial_mps, bond); + // Accept gate only if it doesn't increase max bond dim + // AND reduces local entropy + if trial_max_bond <= current_max_bond && trial_entropy < best_entropy - 1e-2 { + best_entropy = trial_entropy; + best_gate_idx = Some(gate_idx); + } + } + } + + if let Some(idx) = best_gate_idx { + mps.apply_two_site_gate(q, &gates[idx].matrix) + .expect("gate should succeed"); + corrections.push(super::MpsIndexGate { + site: q, + inverse_matrix: gates[idx].inverse_matrix.clone(), + }); + num_applied += 1; + } + } + + // Backward sweep: bonds n-2..0 + for q in (0..n - 1).rev() { + let bond = q + 1; + let current_entropy = bond_entropy(mps, bond); + + if current_entropy < 1e-6 { + continue; + } + + let current_max_bond = mps.max_bond_dim(); + let mut best_entropy = current_entropy; + let mut best_gate_idx: Option = None; + + for (gate_idx, gate) in gates.iter().enumerate() { + let mut trial_mps = mps.clone(); + if trial_mps.apply_two_site_gate(q, &gate.matrix).is_ok() { + let trial_max_bond = trial_mps.max_bond_dim(); + let trial_entropy = bond_entropy(&trial_mps, bond); + if trial_max_bond <= current_max_bond && trial_entropy < best_entropy - 1e-2 { + best_entropy = trial_entropy; + best_gate_idx = Some(gate_idx); + } + } + } + + if let Some(idx) = best_gate_idx { + mps.apply_two_site_gate(q, &gates[idx].matrix) + .expect("gate should succeed"); + corrections.push(super::MpsIndexGate { + site: q, + inverse_matrix: gates[idx].inverse_matrix.clone(), + }); + num_applied += 1; + } + } + + num_applied +} + +/// Run multiple sweeps of disentangling until convergence or `max_sweeps` reached. +pub(crate) fn disentangle( + mps: &mut Mps, + corrections: &mut Vec, + max_sweeps: usize, +) -> usize { + let mut total_applied = 0; + for _ in 0..max_sweeps { + let applied = disentangle_sweep(mps, corrections); + total_applied += applied; + if applied == 0 { + break; + } + } + total_applied +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_disentangler_gate_count() { + let gates = build_disentangler_set(); + eprintln!("Disentangler gate set: {} unique gates", gates.len()); + assert!( + gates.len() >= 15, + "should have at least 15 unique gates, got {}", + gates.len() + ); + + // Verify all gates are unitary + let dim = 4; + let id = DMatrix::::identity(dim, dim); + for (i, gate) in gates.iter().enumerate() { + let product = &gate.matrix * &gate.inverse_matrix; + let diff = (&product - &id).norm(); + assert!( + diff < 1e-10, + "gate {i} is not unitary: ||U*Udg - I|| = {diff}" + ); + } + } +} diff --git a/exp/pecos-stab-tn/src/stab_mps/mast.rs b/exp/pecos-stab-tn/src/stab_mps/mast.rs new file mode 100644 index 000000000..32536d84e --- /dev/null +++ b/exp/pecos-stab-tn/src/stab_mps/mast.rs @@ -0,0 +1,1066 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! MAST: Magic state injection Augmented Stabilizer Tensor network. +//! +//! Instead of applying non-Clifford gates directly (which increases MPS bond +//! dimension), each non-Clifford gate is replaced by: +//! +//! 1. Prepare a magic state |+_T> on a fresh ancilla +//! 2. CNOT between ancilla and target (Clifford -- only touches tableau) +//! 3. Defer the ancilla measurement until the end +//! +//! At the end of the circuit, all deferred measurements are performed. +//! For random circuits with t <= N, most projections are non-entangling, +//! keeping the MPS bond dimension bounded by ~3 on average. +//! +//! # References +//! +//! Nakhl et al., "Stabilizer Tensor Networks with Magic State Injection," +//! PRL 134, 190602 (2025). arXiv:2411.12482. + +use crate::mps::{Mps, MpsConfig}; +use num_complex::Complex64; +use pecos_core::{Angle64, QubitId}; +use pecos_random::PecosRng; +use pecos_simulators::{ + ArbitraryRotationGateable, CliffordGateable, MeasurementResult, QuantumSimulator, SparseStabY, +}; + +use super::non_clifford; + +/// A deferred ancilla measurement. +struct DeferredMeasurement { + /// The ancilla qubit index (in the expanded system). + ancilla: usize, + /// The target data qubit that needs correction if ancilla outcome = 1. + target: usize, + /// The correction angle: RZ(2*theta) applied to target if ancilla = 1. + /// For T gates: correction = RZ(pi/2) = S (Clifford). + correction_angle: Angle64, +} + +/// MAST simulator: Magic state injection Augmented STN. +/// +/// Wraps the STN approach with magic state injection for non-Clifford gates. +/// Pre-allocates ancilla qubits for up to `max_non_clifford` T/RZ gates. +pub struct Mast { + /// Number of data qubits. + num_data_qubits: usize, + /// Maximum number of non-Clifford gates (= number of ancilla slots). + _max_non_clifford: usize, + /// Total qubits = data + ancillas. + total_qubits: usize, + /// The underlying stabilizer tableau for all qubits. + tableau: SparseStabY, + /// The MPS over all qubits. + mps: Mps, + config: MpsConfig, + /// Next available ancilla index. + next_ancilla: usize, + /// Deferred measurements to perform at the end. + deferred: Vec, + global_phase: Complex64, + disent_flags: Vec>, + gf2_matrix: super::ofd::Gf2FlipMatrix, + rng: PecosRng, + pub stats: super::StabMpsStats, + /// Deferred virtual-frame Clifford V for lazy measurement + /// (see `super::measure::DeferredOp`). + deferred_ops: Vec, + /// When `true`, measurement uses the lazy virtual-frame path: + /// accumulates `pre_reduce` CNOTs and post-projection basis-rotation + /// Cliffords into a deferred queue rather than applying them eagerly + /// to the MPS. Set via `with_lazy_measure(true)`. + lazy_measure: bool, + /// Pending non-Clifford RZ angle per qubit when `merge_rz` is on. + /// Flushed when any other gate touches the qubit (except RZ-same-qubit + /// merges, Z/S/Sdg/CZ commutes). Mirror of `StabMps`'s field. + pending_rz: Vec>, + /// When `true`, consecutive `rz(θ, q)` on same qubit merge before + /// invoking magic-state injection. Big win for ion-trap RZ noise. + merge_rz: bool, +} + +impl Mast { + /// Create a MAST simulator with `num_qubits` data qubits and room for + /// `max_non_clifford` non-Clifford gates. + #[must_use] + pub fn new(num_qubits: usize, max_non_clifford: usize) -> Self { + let total = num_qubits + max_non_clifford; + Self { + num_data_qubits: num_qubits, + _max_non_clifford: max_non_clifford, + total_qubits: total, + tableau: SparseStabY::new(total).with_destab_sign_tracking(), + mps: Mps::new(total, MpsConfig::default()), + config: MpsConfig::default(), + next_ancilla: num_qubits, + deferred: Vec::new(), + global_phase: Complex64::new(1.0, 0.0), + disent_flags: vec![Some(super::SiteEigenstate::Z(false)); total], + gf2_matrix: super::ofd::Gf2FlipMatrix::new(total), + rng: PecosRng::seed_from_u64(0), + stats: super::StabMpsStats::default(), + deferred_ops: Vec::new(), + lazy_measure: false, + pending_rz: vec![None; total], + merge_rz: false, + } + } + + /// Create with a specific seed. + #[must_use] + pub fn with_seed(num_qubits: usize, max_non_clifford: usize, seed: u64) -> Self { + let total = num_qubits + max_non_clifford; + Self { + num_data_qubits: num_qubits, + _max_non_clifford: max_non_clifford, + total_qubits: total, + tableau: SparseStabY::with_seed(total, seed).with_destab_sign_tracking(), + mps: Mps::new(total, MpsConfig::default()), + config: MpsConfig::default(), + next_ancilla: num_qubits, + deferred: Vec::new(), + global_phase: Complex64::new(1.0, 0.0), + disent_flags: vec![Some(super::SiteEigenstate::Z(false)); total], + gf2_matrix: super::ofd::Gf2FlipMatrix::new(total), + rng: PecosRng::seed_from_u64(seed), + stats: super::StabMpsStats::default(), + deferred_ops: Vec::new(), + lazy_measure: false, + pending_rz: vec![None; total], + merge_rz: false, + } + } + + /// Enable lazy virtual-frame measurement. Fluent-style setter; returns + /// `self` for chaining after `new`/`with_seed`. See + /// `StabMpsBuilder::lazy_measure` for semantics. + #[must_use] + pub fn with_lazy_measure(mut self, lazy: bool) -> Self { + self.lazy_measure = lazy; + self + } + + /// Enable RZ batching on same qubit. See `StabMpsBuilder::merge_rz` for + /// semantics. Fluent-style setter on MAST. + #[must_use] + pub fn with_merge_rz(mut self, merge: bool) -> Self { + self.merge_rz = merge; + self + } + + /// Flush any pending merged RZ on qubit `q` via magic-state injection. + /// No-op when `merge_rz` is off or the slot is empty. + fn flush_pending_rz(&mut self, q: usize) { + if !self.merge_rz { + return; + } + if let Some(theta) = self.pending_rz[q].take() { + self.rz_apply_direct(theta, q); + } + } + + /// Apply `rz(theta)` on qubit `q` directly (without the merge buffer). + /// Handles Clifford-angle shortcuts and MAST magic-state injection. + fn rz_apply_direct(&mut self, theta: Angle64, q: usize) { + if theta == Angle64::ZERO { + return; + } + let qid = QubitId(q); + if theta == Angle64::HALF_TURN { + self.global_phase *= Complex64::new(0.0, -1.0); + self.tableau.z(&[qid]); + return; + } + if theta == Angle64::QUARTER_TURN { + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + self.global_phase *= Complex64::new(inv_sqrt2, -inv_sqrt2); + self.tableau.sz(&[qid]); + return; + } + if theta == Angle64::THREE_QUARTERS_TURN { + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + self.global_phase *= Complex64::new(inv_sqrt2, inv_sqrt2); + self.tableau.szdg(&[qid]); + return; + } + self.inject_magic_state(theta, q); + } + + /// Flush all pending merged RZ. Public; useful before read operations + /// when `merge_rz` is on. + pub fn flush(&mut self) { + if !self.merge_rz { + return; + } + for q in 0..self.total_qubits { + self.flush_pending_rz(q); + } + } + + #[must_use] + pub fn num_data_qubits(&self) -> usize { + self.num_data_qubits + } + + #[must_use] + pub fn num_ancillas_used(&self) -> usize { + self.next_ancilla - self.num_data_qubits + } + + #[must_use] + pub fn max_bond_dim(&self) -> usize { + self.mps.max_bond_dim() + } + + #[must_use] + pub fn mps(&self) -> &Mps { + &self.mps + } + + /// Inject a magic state for RZ(theta) on the target qubit. + /// + /// Magic state teleportation protocol: + /// 1. Prepare ancilla in |+>: H on ancilla + /// 2. Apply RZ(theta) on ancilla (local, single-site MPS gate) + /// 3. CNOT(target, ancilla) -- **target controls, ancilla is CX target** + /// 4. Defer measurement of ancilla + /// + /// When the ancilla is later measured: + /// - Outcome 0: data qubit has RZ(theta) applied. Done. + /// - Outcome 1: data qubit has RZ(-theta). Correction: RZ(2*theta) on data. + /// For T gate (theta=pi/4): correction = S = RZ(pi/2), which is Clifford. + fn inject_magic_state(&mut self, theta: Angle64, target: usize) { + assert!( + self.next_ancilla < self.total_qubits, + "exceeded max_non_clifford ancilla slots" + ); + + let ancilla = self.next_ancilla; + self.next_ancilla += 1; + + let anc_qid = QubitId(ancilla); + let tgt_qid = QubitId(target); + + // Step 1: Prepare ancilla in |+> + self.tableau.h(&[anc_qid]); + + // Step 2: Apply RZ(theta) on the ancilla. + // Ancilla is in |+> (product state), so Z_anc is a destabilizer flip + // at the ancilla site -- single-site gate, no bond dim growth. + let half_rad = theta.to_radians_signed() / 2.0; + let cos_half = half_rad.cos(); + let sin_half = half_rad.sin(); + non_clifford::apply_rz_stab_mps( + &mut self.tableau, + &mut self.mps, + cos_half, + sin_half, + ancilla, + true, + &mut non_clifford::RzContext { + disent_flags: &mut self.disent_flags, + gf2_matrix: &mut self.gf2_matrix, + stats: &mut self.stats, + }, + ); + + // Step 3: CNOT(target, ancilla) -- target controls, ancilla is CX target + // This is the key: data qubit controls, ancilla flips. + self.tableau.cx(&[(tgt_qid, anc_qid)]); + + // Step 4: Record deferred measurement with correction angle + self.deferred.push(DeferredMeasurement { + ancilla, + target, + correction_angle: theta + theta, // RZ(2*theta) correction if outcome=1 + }); + } + + /// Project all deferred ancilla measurements. + /// + /// For each deferred ancilla: + /// 1. Measure ancilla in Z basis (using shared STN measurement protocol) + /// 2. If outcome = 1: apply RZ(2*theta) correction to the target data qubit + /// (For T gates, this is S = RZ(pi/2), which is Clifford) + pub fn project_all(&mut self) { + let deferred: Vec = self.deferred.drain(..).rev().collect(); + for dm in deferred { + // Measure the ancilla using the shared STN measurement protocol + let result = if self.lazy_measure { + super::measure::measure_qubit_stab_mps_lazy( + &mut self.tableau, + &mut self.mps, + &mut self.rng, + dm.ancilla, + &mut self.deferred_ops, + ) + } else { + super::measure::measure_qubit_stab_mps( + &mut self.tableau, + &mut self.mps, + &mut self.rng, + dm.ancilla, + ) + }; + + // If outcome = 1 (true in PECOS convention): apply correction + if result.outcome { + let corr = dm.correction_angle; + let tgt = QubitId(dm.target); + + // Check if correction is a Clifford angle + if corr == Angle64::ZERO { + // No correction needed + } else if corr == Angle64::HALF_TURN { + // RZ(pi) = -iZ + self.global_phase *= Complex64::new(0.0, -1.0); + self.tableau.z(&[tgt]); + } else if corr == Angle64::QUARTER_TURN { + // RZ(pi/2) = e^{-i*pi/4} S -- this is the T gate correction + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + self.global_phase *= Complex64::new(inv_sqrt2, -inv_sqrt2); + self.tableau.sz(&[tgt]); + } else if corr == Angle64::THREE_QUARTERS_TURN { + let inv_sqrt2 = std::f64::consts::FRAC_1_SQRT_2; + self.global_phase *= Complex64::new(inv_sqrt2, inv_sqrt2); + self.tableau.szdg(&[tgt]); + } else { + // Non-Clifford correction: apply via STN protocol + let (sin_half, cos_half) = corr.half_angle_sin_cos(); + non_clifford::apply_rz_stab_mps( + &mut self.tableau, + &mut self.mps, + cos_half, + sin_half, + dm.target, + true, + &mut non_clifford::RzContext { + disent_flags: &mut self.disent_flags, + gf2_matrix: &mut self.gf2_matrix, + stats: &mut self.stats, + }, + ); + } + } + } + } +} + +impl QuantumSimulator for Mast { + fn reset(&mut self) -> &mut Self { + self.tableau = SparseStabY::new(self.total_qubits).with_destab_sign_tracking(); + self.mps = Mps::new(self.total_qubits, self.config.clone()); + self.next_ancilla = self.num_data_qubits; + self.deferred.clear(); + self.global_phase = Complex64::new(1.0, 0.0); + self.disent_flags = vec![Some(super::SiteEigenstate::Z(false)); self.total_qubits]; + self.gf2_matrix.reset(); + self.deferred_ops.clear(); + for slot in &mut self.pending_rz { + *slot = None; + } + self + } + + fn num_qubits(&self) -> usize { + self.num_data_qubits + } +} + +impl CliffordGateable for Mast { + fn sz(&mut self, qubits: &[QubitId]) -> &mut Self { + self.tableau.sz(qubits); + self + } + + fn h(&mut self, qubits: &[QubitId]) -> &mut Self { + // H does not commute with RZ: flush pending merged RZ first. + for &q in qubits { + self.flush_pending_rz(q.index()); + } + self.tableau.h(qubits); + self + } + + fn cx(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + // CX doesn't commute with RZ on arbitrary qubits: flush both. + for &(c, t) in pairs { + self.flush_pending_rz(c.index()); + self.flush_pending_rz(t.index()); + } + self.tableau.cx(pairs); + self + } + + fn cz(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + // CZ is diagonal, commutes with RZ on either qubit — no flush needed. + self.tableau.cz(pairs); + self + } + + fn mz(&mut self, qubits: &[QubitId]) -> Vec { + // Flush any pending merged RZ on measured qubits before measuring. + for &q in qubits { + self.flush_pending_rz(q.index()); + } + // Project all deferred measurements first + self.project_all(); + // Then measure data qubits using the full STN measurement protocol + qubits + .iter() + .map(|&q| { + if self.lazy_measure { + super::measure::measure_qubit_stab_mps_lazy( + &mut self.tableau, + &mut self.mps, + &mut self.rng, + q.index(), + &mut self.deferred_ops, + ) + } else { + super::measure::measure_qubit_stab_mps( + &mut self.tableau, + &mut self.mps, + &mut self.rng, + q.index(), + ) + } + }) + .collect() + } +} + +impl ArbitraryRotationGateable for Mast { + fn rx(&mut self, theta: Angle64, qubits: &[QubitId]) -> &mut Self { + self.h(qubits); + self.rz(theta, qubits); + self.h(qubits); + self + } + + fn rz(&mut self, theta: Angle64, qubits: &[QubitId]) -> &mut Self { + for &q in qubits { + let q_idx = q.index(); + if !self.merge_rz { + self.rz_apply_direct(theta, q_idx); + continue; + } + let is_clifford_angle = theta == Angle64::ZERO + || theta == Angle64::HALF_TURN + || theta == Angle64::QUARTER_TURN + || theta == Angle64::THREE_QUARTERS_TURN; + if is_clifford_angle { + // Clifford-angle RZ commutes with pending non-Clifford RZ; + // no flush needed, apply directly. + self.rz_apply_direct(theta, q_idx); + } else { + let prev = self.pending_rz[q_idx].unwrap_or(Angle64::ZERO); + let merged = prev + theta; + if merged == Angle64::ZERO + || merged == Angle64::HALF_TURN + || merged == Angle64::QUARTER_TURN + || merged == Angle64::THREE_QUARTERS_TURN + { + self.pending_rz[q_idx] = None; + self.rz_apply_direct(merged, q_idx); + } else { + self.pending_rz[q_idx] = Some(merged); + } + } + } + self + } + + fn rzz(&mut self, theta: Angle64, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q0, q1) in pairs { + self.cx(&[(q0, q1)]); + self.rz(theta, &[q1]); + self.cx(&[(q0, q1)]); + } + self + } +} + +#[cfg(test)] +mod tests { + use super::*; + use approx::assert_relative_eq; + + #[test] + fn test_mast_pure_clifford() { + // Pure Clifford circuit should work like STN + let mut mast = Mast::new(2, 4); + mast.h(&[QubitId(0)]); + mast.cx(&[(QubitId(0), QubitId(1))]); + assert_eq!(mast.num_ancillas_used(), 0); + assert_eq!(mast.max_bond_dim(), 1); + } + + #[test] + fn test_mast_single_t_gate() { + // T gate uses magic state injection + let mut mast = Mast::new(1, 4); + mast.h(&[QubitId(0)]); + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + assert_eq!(mast.num_ancillas_used(), 1); + // Bond dim should be low -- the RZ on the ancilla is a single-site gate + assert!( + mast.max_bond_dim() <= 2, + "bond dim should be low, got {}", + mast.max_bond_dim() + ); + } + + #[test] + fn test_mast_norm_preserved() { + let mut mast = Mast::new(2, 4); + mast.h(&[QubitId(0)]); + mast.cx(&[(QubitId(0), QubitId(1))]); + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(1)]); + + assert_relative_eq!(mast.mps().norm_squared(), 1.0, epsilon = 1e-8); + } + + #[test] + fn test_mast_t_on_zero_deterministic() { + // T|0> via MAST: data stays in |0>, measurement should be deterministic + for trial in 0..20 { + let mut mast = Mast::with_seed(1, 4, 7000 + trial); + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let r = mast.mz(&[QubitId(0)]); + assert!(!r[0].outcome, "trial {trial}: T|0> should measure as 0"); + } + } + + #[test] + fn test_mast_t_on_plus_statistics() { + // H then T via MAST, then measure: should get 50/50 (T only changes phase) + let num_trials = 200; + let mut count_0 = 0; + for trial in 0..num_trials { + let mut mast = Mast::with_seed(1, 4, 8000 + trial); + mast.h(&[QubitId(0)]); + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let r = mast.mz(&[QubitId(0)]); + if !r[0].outcome { + count_0 += 1; + } + } + let p0 = f64::from(count_0) / num_trials as f64; + assert!((p0 - 0.5).abs() < 0.1, "p(0) = {p0:.2}, expected ~0.5"); + } + + /// Multi-qubit MAST vs STN: sample measurement distributions on a + /// Clifford+T circuit. Each of the 2^n outcomes should have matching + /// probabilities between MAST and STN. + #[test] + fn test_mast_vs_stn_multi_qubit() { + use crate::stab_mps::StabMps; + let num_trials = 1000; + let n = 4; + // Circuit: H on all, CX(0,1), T(0), CX(1,2), T(1), CX(2,3), T(2) + let apply = |s: &mut dyn FnMut(&[QubitId])| { + let _ = s; + }; + let _ = apply; + + let mut stn_counts = vec![0u32; 1 << n]; + let mut mast_counts = vec![0u32; 1 << n]; + for trial in 0..num_trials { + // STN + let mut s = StabMps::with_seed(n, 10_000 + trial); + s.h(&[QubitId(0), QubitId(1), QubitId(2), QubitId(3)]); + s.cx(&[(QubitId(0), QubitId(1))]); + s.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + s.cx(&[(QubitId(1), QubitId(2))]); + s.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(1)]); + s.cx(&[(QubitId(2), QubitId(3))]); + s.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(2)]); + let mut idx = 0usize; + for q in 0..n { + if s.mz(&[QubitId(q)])[0].outcome { + idx |= 1 << q; + } + } + stn_counts[idx] += 1; + + // MAST + let mut m = Mast::with_seed(n, 10, 10_000 + trial); + m.h(&[QubitId(0), QubitId(1), QubitId(2), QubitId(3)]); + m.cx(&[(QubitId(0), QubitId(1))]); + m.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + m.cx(&[(QubitId(1), QubitId(2))]); + m.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(1)]); + m.cx(&[(QubitId(2), QubitId(3))]); + m.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(2)]); + let mut idx = 0usize; + for q in 0..n { + if m.mz(&[QubitId(q)])[0].outcome { + idx |= 1 << q; + } + } + mast_counts[idx] += 1; + } + + // Chi-squared-like check: each outcome should have close probabilities. + let mut max_diff: f64 = 0.0; + for i in 0..(1 << n) { + let p_stn = f64::from(stn_counts[i]) / num_trials as f64; + let p_mast = f64::from(mast_counts[i]) / num_trials as f64; + let diff = (p_stn - p_mast).abs(); + if diff > max_diff { + max_diff = diff; + } + eprintln!("outcome {i:04b}: STN={p_stn:.3}, MAST={p_mast:.3}"); + } + eprintln!("max |p_STN - p_MAST| = {max_diff:.3}"); + // Statistical tolerance for 1000 trials ~= 3 sigma on p=0.5 is 0.047. + // Use 0.08 to allow for multiple-outcome max. + assert!( + max_diff < 0.08, + "MAST and STN distributions diverge: max diff {max_diff:.3}" + ); + } + + #[test] + fn test_mast_vs_stn_single_qubit() { + // Compare MAST and STN state vectors for H, T on single qubit + use crate::stab_mps::StabMps; + + let mut stn = StabMps::new(1); + stn.h(&[QubitId(0)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let _stn_sv = stn.state_vector(); + + // MAST: the state vector includes ancilla qubits, so we can't + // directly compare. But the data qubit probabilities should match. + // Use measurement statistics instead. + let num_trials = 500; + let mut stn_count = 0; + let mut mast_count = 0; + for trial in 0..num_trials { + let mut s = StabMps::with_seed(1, 9000 + trial); + s.h(&[QubitId(0)]); + s.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + if !s.mz(&[QubitId(0)])[0].outcome { + stn_count += 1; + } + + let mut m = Mast::with_seed(1, 4, 9000 + trial); + m.h(&[QubitId(0)]); + m.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + if !m.mz(&[QubitId(0)])[0].outcome { + mast_count += 1; + } + } + let stn_p0 = f64::from(stn_count) / num_trials as f64; + let mast_p0 = f64::from(mast_count) / num_trials as f64; + eprintln!("STN p(0) = {stn_p0:.3}, MAST p(0) = {mast_p0:.3}"); + // Both should be ~0.5 (T only changes phase, not Z-basis probabilities) + assert!( + (stn_p0 - mast_p0).abs() < 0.1, + "STN p(0)={stn_p0:.3} vs MAST p(0)={mast_p0:.3} should be similar" + ); + } + + #[test] + fn test_stn_3qubit_measurement_correlation() { + // Test that STN gives same results as plain SparseStabY for pure Clifford. + use crate::stab_mps::StabMps; + + let mut stn_corr = 0; + let mut tab_corr = 0; + let num_trials = 50; + for trial in 0..num_trials { + // STN version + let mut stn = StabMps::with_seed(3, 6000 + trial); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.h(&[QubitId(2)]); + stn.cx(&[(QubitId(0), QubitId(2))]); + let r2_stn = stn.mz(&[QubitId(2)])[0].outcome; + let r0_stn = stn.mz(&[QubitId(0)])[0].outcome; + if r0_stn == r2_stn { + stn_corr += 1; + } + + // Plain SparseStabY version (same seed) + let mut tab = SparseStabY::with_seed(3, 6000 + trial); + tab.h(&[QubitId(0)]); + tab.cx(&[(QubitId(0), QubitId(1))]); + tab.h(&[QubitId(2)]); + tab.cx(&[(QubitId(0), QubitId(2))]); + let r2_tab = tab.mz(&[QubitId(2)])[0].outcome; + let r0_tab = tab.mz(&[QubitId(0)])[0].outcome; + if r0_tab == r2_tab { + tab_corr += 1; + } + } + let stn_rate = f64::from(stn_corr) / num_trials as f64; + let tab_rate = f64::from(tab_corr) / num_trials as f64; + eprintln!("STN correlation: {stn_rate:.2}, SparseStabY correlation: {tab_rate:.2}"); + // Both should match + assert!( + (stn_rate - tab_rate).abs() < 0.2, + "STN {stn_rate:.2} should match SparseStabY {tab_rate:.2}" + ); + } + + #[test] + fn test_manual_mast_with_sparse_stab() { + // Verify the magic state teleportation protocol using plain SparseStabY. + // This tests the PROTOCOL, not the STN implementation. + let mut correlated = 0; + let num_trials = 100; + for trial in 0..num_trials { + let mut tab = SparseStabY::with_seed(3, 7000 + trial); + // Bell state on q0, q1 + tab.h(&[QubitId(0)]); + tab.cx(&[(QubitId(0), QubitId(1))]); + // Magic state injection for T on q0: + tab.h(&[QubitId(2)]); // ancilla in |+> + tab.sz(&[QubitId(2)]); // S on ancilla (half of T = S*T^{1/2}... wait, we need T) + // Actually, SparseStabY can't do T. Let me use T = RZ(pi/4) via the Clifford S. + // T|+> via Clifford: not possible. T is non-Clifford. + // In the SparseStabY world, we can test the protocol with S instead of T. + // S|+> = (|0> + i|1>)/sqrt(2) + // Protocol: prepare S|+>, CNOT(data, anc), measure anc, correct. + // For S: correction if outcome=1 is RZ(2*pi/2)=RZ(pi)=-iZ (Clifford). + // S gate on q0 of Bell state: (|00> + i|11>)/sqrt(2) + // CNOT(q0, q2): + tab.cx(&[(QubitId(0), QubitId(2))]); + let anc_result = tab.mz(&[QubitId(2)])[0].outcome; + if anc_result { + // Correction: RZ(pi) = -iZ on q0 + tab.z(&[QubitId(0)]); + } + let r0 = tab.mz(&[QubitId(0)])[0].outcome; + let r1 = tab.mz(&[QubitId(1)])[0].outcome; + if r0 == r1 { + correlated += 1; + } + } + let rate = f64::from(correlated) / num_trials as f64; + eprintln!("SparseStabY manual S-injection correlation: {rate:.2}"); + assert!(rate > 0.90, "correlation {rate:.2} should be > 0.90"); + } + + #[test] + fn test_manual_mast_with_stn_clifford() { + // Manual MAST with S (Clifford) instead of T. + // This should work because the MPS stays trivial. + use crate::stab_mps::StabMps; + + let mut correlated = 0; + let num_trials = 100; + for trial in 0..num_trials { + let mut stn = StabMps::with_seed(3, 5000 + trial); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + + // S-injection (Clifford, MPS stays trivial): + stn.h(&[QubitId(2)]); + stn.sz(&[QubitId(2)]); // S instead of T + stn.cx(&[(QubitId(0), QubitId(2))]); + let anc_result = stn.mz(&[QubitId(2)])[0].outcome; + if anc_result { + stn.z(&[QubitId(0)]); // RZ(pi) correction for S + } + + let r0 = stn.mz(&[QubitId(0)])[0].outcome; + let r1 = stn.mz(&[QubitId(1)])[0].outcome; + if r0 == r1 { + correlated += 1; + } + } + let rate = f64::from(correlated) / num_trials as f64; + eprintln!("STN Clifford injection correlation: {rate:.2}"); + assert!(rate > 0.90, "correlation {rate:.2} should be > 0.90"); + } + + #[test] + fn test_z2_expectation_value() { + // Verify the Z_2 expectation value matches between STN and direct computation. + use crate::stab_mps::StabMps; + use nalgebra::DMatrix; + use pecos_simulators::StabVec; + + let mut stn = StabMps::new(3); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.h(&[QubitId(2)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(2)]); + stn.cx(&[(QubitId(0), QubitId(2))]); + + // Compute from state vector + let mut crz = StabVec::builder(3).seed(42).build(); + crz.h(&[QubitId(0)]); + crz.cx(&[(QubitId(0), QubitId(1))]); + crz.h(&[QubitId(2)]); + crz.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(2)]); + crz.cx(&[(QubitId(0), QubitId(2))]); + let crz_sv = crz.state_vector(); + + // from state vector: sum |a_i|^2 * (-1)^{bit 2 of i} + let mut z2_ev_direct = 0.0; + for (i, a) in crz_sv.iter().enumerate() { + let bit2 = (i >> 2) & 1; // qubit 2 in LSB convention + let sign = if bit2 == 1 { -1.0 } else { 1.0 }; + z2_ev_direct += a.norm_sqr() * sign; + } + + // from STN decomposition + let decomp = crate::stab_mps::pauli_decomp::decompose_z( + stn.tableau().stabs(), + stn.tableau().destabs(), + 2, + ); + eprintln!("Z_2 decomp: {decomp:?}"); + + let z_gate = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(-1.0, 0.0), + ], + ); + let x_gate = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + + if let crate::stab_mps::pauli_decomp::ZDecomposition::DestabilizerFlip { + flip_sites, + phase, + sign_sites, + } = decomp + { + let mut ops: Vec<(usize, DMatrix)> = Vec::new(); + for j in &flip_sites { + ops.push((*j, x_gate.clone())); + } + for k in &sign_sites { + ops.push((*k, z_gate.clone())); + } + let raw_ev = stn.mps().expectation_product(&ops); + let z2_ev_stn = (phase * raw_ev).re; + eprintln!("Z_2 EV: direct={z2_ev_direct:.6}, STN={z2_ev_stn:.6}, phase={phase:.4}"); + approx::assert_relative_eq!(z2_ev_stn, z2_ev_direct, epsilon = 1e-6); + } + } + + #[test] + fn test_stn_state_before_ancilla_measurement() { + // Check that the STN state vector before ancilla measurement is correct. + use crate::stab_mps::StabMps; + use pecos_simulators::StabVec; + + let mut stn = StabMps::new(3); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.h(&[QubitId(2)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(2)]); + stn.cx(&[(QubitId(0), QubitId(2))]); + + let mut crz = StabVec::builder(3).seed(42).build(); + crz.h(&[QubitId(0)]); + crz.cx(&[(QubitId(0), QubitId(1))]); + crz.h(&[QubitId(2)]); + crz.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(2)]); + crz.cx(&[(QubitId(0), QubitId(2))]); + + let stn_sv = stn.state_vector(); + let crz_sv = crz.state_vector(); + + // Check overlap + let norm_stn: f64 = stn_sv.iter().map(nalgebra::Complex::norm_sqr).sum(); + let norm_crz: f64 = crz_sv.iter().map(nalgebra::Complex::norm_sqr).sum(); + let overlap: Complex64 = stn_sv + .iter() + .zip(crz_sv.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + + eprintln!( + "State before ancilla meas: norm_stn={norm_stn:.4}, norm_crz={norm_crz:.4}, overlap={:.4}", + overlap.norm_sqr() + ); + assert!( + (overlap.norm_sqr() - 1.0).abs() < 0.01, + "states should match (overlap = {:.4})", + overlap.norm_sqr() + ); + } + + #[test] + fn test_manual_mast_with_stn_nonclifford() { + // Manual MAST with T (non-Clifford). + // This tests whether the STN measurement handles the ancilla correctly. + use crate::stab_mps::StabMps; + + let mut correlated = 0; + let num_trials = 100; + for trial in 0..num_trials { + let mut stn = StabMps::with_seed(3, 5000 + trial); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + + // T-injection (non-Clifford): + stn.h(&[QubitId(2)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(2)]); + stn.cx(&[(QubitId(0), QubitId(2))]); + let anc_result = stn.mz(&[QubitId(2)])[0].outcome; + if anc_result { + stn.sz(&[QubitId(0)]); // S correction + } + + let r0 = stn.mz(&[QubitId(0)])[0].outcome; + let r1 = stn.mz(&[QubitId(1)])[0].outcome; + if r0 == r1 { + correlated += 1; + } + } + let rate = f64::from(correlated) / num_trials as f64; + eprintln!("STN T-injection correlation: {rate:.2}"); + assert!(rate > 0.90, "correlation {rate:.2} should be > 0.90"); + } + + #[test] + fn test_mast_measurement() { + // Bell state + T via MAST: after ancilla projection, data qubits + // should be in Bell+T state with correlated measurements. + // + // Diagnose: check MPS norm and bond dims after each step. + let mut mast = Mast::with_seed(2, 4, 42); + mast.h(&[QubitId(0)]); + mast.cx(&[(QubitId(0), QubitId(1))]); + + eprintln!( + "After Bell: norm={:.4}, bonds={:?}", + mast.mps().norm_squared(), + mast.mps().bond_dims() + ); + + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + + eprintln!( + "After T inject: norm={:.4}, bonds={:?}, ancillas={}", + mast.mps().norm_squared(), + mast.mps().bond_dims(), + mast.num_ancillas_used() + ); + + // Project deferred measurements + mast.project_all(); + + eprintln!( + "After project: norm={:.4}, bonds={:?}", + mast.mps().norm_squared(), + mast.mps().bond_dims() + ); + + // Check MPS state + let mps_sv = mast.mps().state_vector(); + eprintln!("MPS SV after project:"); + for (i, a) in mps_sv.iter().enumerate() { + if a.norm() > 1e-12 { + eprintln!(" [{i:06b}] = {:.4} + {:.4}i", a.re, a.im); + } + } + + // Now measure both data qubits + let mut correlated = 0; + let num_trials = 100; + for trial in 0..num_trials { + let mut m = Mast::with_seed(2, 4, 5000 + trial); + m.h(&[QubitId(0)]); + m.cx(&[(QubitId(0), QubitId(1))]); + m.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + + let r0 = m.mz(&[QubitId(0)])[0].outcome; + let r1 = m.mz(&[QubitId(1)])[0].outcome; + if r0 == r1 { + correlated += 1; + } + } + let correlation_rate = f64::from(correlated) / num_trials as f64; + eprintln!("Correlation rate: {correlation_rate:.2}"); + assert!( + correlation_rate > 0.90, + "correlation rate {correlation_rate:.2} should be > 0.90" + ); + } + + #[test] + fn test_mast_merge_rz_two_t_gates_merge() { + // Two T on same qubit with merge_rz should produce a single + // non-Clifford (merged to S = Clifford fast-path). Eager path + // would do two MAST injections. + let t = Angle64::QUARTER_TURN / 2u64; + let mut m = Mast::with_seed(2, 4, 7).with_merge_rz(true); + m.h(&[QubitId(0)]); + m.rz(t, &[QubitId(0)]); + m.rz(t, &[QubitId(0)]); + m.flush(); + // T+T = S (Clifford). No ancillas used. + assert_eq!( + m.num_ancillas_used(), + 0, + "T+T should merge to S (Clifford), no MAST ancillas used" + ); + } + + #[test] + fn test_mast_merge_rz_intervening_cz_still_merges() { + // CZ on different qubits doesn't flush pending_rz on q0. Merge. + let t = Angle64::QUARTER_TURN / 2u64; + let mut m = Mast::with_seed(2, 4, 9).with_merge_rz(true); + m.h(&[QubitId(0), QubitId(1)]); + m.rz(t, &[QubitId(0)]); + m.cz(&[(QubitId(0), QubitId(1))]); // CZ commutes with RZ + m.rz(t, &[QubitId(0)]); + m.flush(); + // Merged T+T = S. No MAST ancilla used. + assert_eq!( + m.num_ancillas_used(), + 0, + "CZ should not flush pending_rz, merge persists" + ); + } + + #[test] + fn test_mast_with_lazy_measure_bell_correlation() { + // Fluent setter on MAST: measurements via lazy path. + for trial in 0..10 { + let mut m = Mast::with_seed(2, 4, 5000 + trial).with_lazy_measure(true); + m.h(&[QubitId(0)]); + m.cx(&[(QubitId(0), QubitId(1))]); + m.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let r0 = m.mz(&[QubitId(0)])[0].outcome; + let r1 = m.mz(&[QubitId(1)])[0].outcome; + assert_eq!(r0, r1, "lazy MAST Bell+T trial {trial}"); + } + } +} diff --git a/exp/pecos-stab-tn/src/stab_mps/measure.rs b/exp/pecos-stab-tn/src/stab_mps/measure.rs new file mode 100644 index 000000000..4f6fcac82 --- /dev/null +++ b/exp/pecos-stab-tn/src/stab_mps/measure.rs @@ -0,0 +1,1382 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Shared measurement logic for STN and MAST simulators. +//! +//! Measures a qubit in the Z basis using the stabilizer tableau for structure +//! and the MPS for probability computation and projection. +//! +//! The measurement protocol decomposes `Z_q` in the stabilizer basis, computes +//! the expectation value from the MPS, samples an outcome, and projects the +//! MPS using the (I + sign * `Z_q)/2` projector. After projection, the measured +//! site collapses to sigma=0 (the stabilizer eigenstate). +//! +//! Reference: Masot-Llima, Garcia-Saez. arXiv:2403.08724, Section III. + +use super::pauli_decomp::{ZDecomposition, decompose_z}; +use crate::mps::Mps; +use nalgebra::DMatrix; +use num_complex::Complex64; +use pecos_random::PecosRng; +use pecos_simulators::{CliffordGateable, MeasurementResult, SparseStabY}; + +/// Check if the MPS is trivial (all sites in a computational basis state). +fn is_mps_trivial(mps: &Mps) -> bool { + mps.max_bond_dim() == 1 + && mps.tensors().iter().all(|t| { + let chi_r = t.ncols() / 2; + let b0_norm: f64 = (0..t.nrows()) + .flat_map(|i| (0..chi_r).map(move |j| t[(i, j)].norm_sqr())) + .sum(); + let b1_norm: f64 = (0..t.nrows()) + .flat_map(|i| (0..chi_r).map(move |j| t[(i, chi_r + j)].norm_sqr())) + .sum(); + b0_norm < 1e-12 || b1_norm < 1e-12 + }) +} + +/// Compute `` via clone + inner product. +/// +/// Returns the expectation value of the Pauli string. Z applied first, then +/// X (matches the measurement projection convention in this module). +/// +/// # Panics +/// +/// Panics if any MPS gate application fails on a valid site (should not happen +/// for in-range sites). +#[must_use] +pub fn pauli_expectation( + mps: &Mps, + flip_sites: &[usize], + sign_sites: &[usize], + phase: Complex64, +) -> Complex64 { + if flip_sites.is_empty() && sign_sites.is_empty() { + return phase; + } + let x_gate = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let z_diag = [Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)]; + let mut mps_op = mps.clone(); + for &k in sign_sites { + mps_op + .apply_diagonal_one_site(k, &z_diag) + .expect("MPS op on valid site"); + } + for &j in flip_sites { + mps_op + .apply_one_site_gate(j, &x_gate) + .expect("MPS op on valid site"); + } + let raw = mps_inner_product(mps, &mps_op); + phase * raw +} + +/// Compute `` by applying the decomposition to a clone and taking the inner product. +/// +/// Returns the raw expectation value (before multiplying by the decomposition phase). +/// The full expectation is: `phase * apply_z_to_clone_and_overlap(...)`. +#[must_use] +pub fn z_expectation_value(tableau: &SparseStabY, mps: &Mps, q: usize) -> Complex64 { + let decomp = decompose_z(tableau.stabs(), tableau.destabs(), q); + match decomp { + ZDecomposition::Stabilizer { phase, sign_sites } => { + pauli_expectation(mps, &[], &sign_sites, phase) + } + ZDecomposition::DestabilizerFlip { + flip_sites, + phase, + sign_sites, + } => pauli_expectation(mps, &flip_sites, &sign_sites, phase), + } +} + +/// Compute the inner product <`mps_a|mps_b`> by contracting from left to right. +fn mps_inner_product(mps_a: &Mps, mps_b: &Mps) -> Complex64 { + let d = mps_a.phys_dim(); + let mut transfer = DMatrix::from_element(1, 1, Complex64::new(1.0, 0.0)); + + for q in 0..mps_a.num_sites() { + let chi_r_a = mps_a.bond_dim(q + 1); + let chi_r_b = mps_b.bond_dim(q + 1); + let t_a = &mps_a.tensors()[q]; + let t_b = &mps_b.tensors()[q]; + + let mut new_transfer = DMatrix::zeros(chi_r_a, chi_r_b); + for sigma in 0..d { + let block_a = crate::mps::tensor::phys_block(t_a, sigma, chi_r_a); + let block_b = crate::mps::tensor::phys_block(t_b, sigma, chi_r_b); + let conj_a_t = block_a.conjugate().transpose(); + let tmp = &conj_a_t * &transfer * &block_b; + new_transfer += tmp; + } + transfer = new_transfer; + } + + transfer[(0, 0)] +} + +/// Find the stabilizer index that `mz_forced` will select for replacement. +/// +/// This is the minimum-weight stabilizer that anticommutes with `Z_q`, +/// matching the logic in `SparseStabY::nondeterministic_meas`. +fn find_replaced_stabilizer(tableau: &SparseStabY, q_idx: usize) -> usize { + let stabs = tableau.stabs(); + let col_x = &stabs.col_x[q_idx]; + + let mut best_id = None; + let mut best_weight = usize::MAX; + for stab_id in col_x { + let weight = stabs.row_x[stab_id].len() + stabs.row_z[stab_id].len(); + if weight < best_weight { + best_weight = weight; + best_id = Some(stab_id); + if weight == 1 { + break; + } + } + } + best_id.expect("col_x should be non-empty for DestabilizerFlip case") +} + +/// Test hook for `pre_reduce_for_measurement`. +pub fn pre_reduce_for_measurement_pub(tableau: &mut SparseStabY, mps: &mut Mps, q_idx: usize) { + pre_reduce_for_measurement(tableau, mps, q_idx, true); +} + +/// Pre-reduce the stabilizer tableau so that `Z_q` anticommutes with at most +/// one stabilizer. For each other anti-commuting stab: +/// - Tableau: `S[other] *= S[replaced]`, `D[replaced] *= D[other]` (via +/// full Y-convention `multiply_row`, including sign/phase tracking). +/// - MPS (when `apply_mps_compensation=true`): apply virtual-frame +/// `CNOT(c=replaced, t=other)` for CAMPS state preservation. The tableau +/// change transforms the Clifford as `C → C · CNOT` — applying the +/// same CNOT to the MPS (self-inverse) compensates so +/// `C'·MPS_new = C·MPS_old`. Non-adjacent CNOTs use +/// `apply_long_range_two_site_gate`. +/// +/// `apply_mps_compensation` is `true` for exact-state callers +/// (`project_forced_z`, `project_forced_z_unnormalized`) used by +/// `prob_bitstring` / `amplitude_iterative`. It is `false` for random +/// measurement (`measure_qubit_stab_mps`): the state representation becomes +/// inconsistent with the tableau after row ops, but measurement +/// statistics stay correct and subsequent measurements remain +/// self-consistent. Skipping compensation avoids SWAP-chain bond growth +/// during measurement-heavy circuits (MAST magic-state injection). +/// +/// Proper long-term fix: lazy virtual-frame tracking — accumulate a +/// deferred Clifford V such that effective MPS = V·stored MPS, conjugate +/// Pauli strings by V before applying to stored MPS, flush only when MPS +/// must be read directly. See `docs/future_work.md`. +fn pre_reduce_for_measurement( + tableau: &mut SparseStabY, + mps: &mut Mps, + q_idx: usize, + apply_mps_compensation: bool, +) { + let col_x = &tableau.stabs().col_x[q_idx]; + if col_x.len() <= 1 { + return; + } + + let replaced_idx = find_replaced_stabilizer(tableau, q_idx); + let n = tableau.num_qubits(); + + let anticom: Vec = tableau.stabs().col_x[q_idx] + .iter() + .filter(|&id| id != replaced_idx) + .collect(); + + // Clone stabs/destabs ONCE before the loop (not per iteration). + // For stabs: replaced_idx is the SOURCE row and never modified, so one + // clone suffices for all iterations. + // For destabs: replaced_idx IS modified (accumulated), but the SOURCE + // rows (other_id) are all distinct and untouched. One clone captures + // all of them before any mutation. + let stabs_snapshot = tableau.stabs().clone(); + let destabs_snapshot = tableau.destabs().clone(); + for other_id in anticom { + crate::stab_mps::tableau_compose::multiply_row( + tableau.stabs_mut(), + other_id, + &stabs_snapshot, + replaced_idx, + n, + ); + crate::stab_mps::tableau_compose::multiply_row( + tableau.destabs_mut(), + replaced_idx, + &destabs_snapshot, + other_id, + n, + ); + if apply_mps_compensation { + apply_cnot_to_mps(mps, replaced_idx, other_id); + } + } +} + +pub fn apply_cnot_to_mps(mps: &mut Mps, control: usize, target: usize) { + // Optimization: if the control site has no |1⟩_virt amplitude, CNOT is + // identity on this MPS — skip to avoid bond-dim blowup from SWAP chains. + // Mirror: if control has no |0⟩_virt amp, CNOT reduces to X on target. + if mps_site_block_is_zero(mps, control, 1) { + return; + } + if mps_site_block_is_zero(mps, control, 0) { + // Control is |1⟩ → CNOT unconditionally flips target = X on target. + let x_gate = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + mps.apply_one_site_gate(target, &x_gate) + .expect("MPS op on valid site"); + return; + } + + // General case: apply full CNOT. + let o = Complex64::new(0.0, 0.0); + let one = Complex64::new(1.0, 0.0); + let cnot_c_lo = DMatrix::from_row_slice( + 4, + 4, + &[one, o, o, o, o, one, o, o, o, o, o, one, o, o, one, o], + ); + let cnot_c_hi = DMatrix::from_row_slice( + 4, + 4, + &[one, o, o, o, o, o, o, one, o, o, one, o, o, one, o, o], + ); + let (q0, q1, gate) = if control < target { + (control, target, cnot_c_lo) + } else { + (target, control, cnot_c_hi) + }; + if q1 == q0 + 1 { + mps.apply_two_site_gate(q0, &gate) + .expect("MPS op on valid site"); + } else { + mps.apply_long_range_two_site_gate(q0, q1, &gate) + .expect("MPS op on valid site"); + } +} + +/// A deferred Clifford primitive in the virtual-frame queue. +/// +/// The queue represents a Clifford `V = ops[last] · ... · ops[0]` where +/// index 0 is the first pushed (earliest applied if flushed). Each primitive +/// has a cheap Heisenberg conjugation rule (bit XOR on flip/sign sets) and +/// a cheap MPS application (single-site for H, diagonal for CZ, SWAP-chain +/// for CNOT). +#[derive(Clone, Copy, Debug)] +pub enum DeferredOp { + /// CNOT(control, target). + Cnot(usize, usize), + /// Hadamard on qubit. + H(usize), + /// CZ(a, b) — symmetric. + Cz(usize, usize), + /// Pauli Z on qubit. Used for outcome-dependent W basis rotation: + /// for outcome=1, W includes a `Z_id` factor to flip `Z_id` → -`X_id`. + Z(usize), + /// Phase gate adjoint (SZ†) — needed for outcome-dependent W when + /// flip and sign overlap at id (Y-like Pauli). + SZdg(usize), + /// Phase gate SZ — needed for outcome-dependent W when the + /// decomposition phase `sp` is purely imaginary. Conjugation rule: + /// SZ†·P·SZ — if X at q, toggle Z at q and multiply phase by -i. + SZ(usize), +} + +fn toggle(v: &mut Vec, x: usize) { + if let Some(pos) = v.iter().position(|&y| y == x) { + v.swap_remove(pos); + } else { + v.push(x); + } +} + +/// Conjugate a Pauli `P = X_flip · Z_sign` by `V†` where +/// `V = ops[last] · ops[last-1] · ... · ops[0]`. Updates `flip_sites` and +/// `sign_sites` in place to represent `V† · P · V`. The scalar phase is +/// unchanged (CNOT/H/CZ conjugation preserves phase of the product). +/// +/// Heisenberg rules: +/// - CNOT(c, t): `X_c -> X_c · X_t`; `Z_t -> Z_c · Z_t`. +/// - H(q): swap `X_q` and `Z_q` (swap q between flip and sign). +/// - CZ(a, b): `X_a -> X_a · Z_b`; `X_b -> X_b · Z_a`. +/// +/// Order: `V† P V = op_0·...·op_last·P·op_last·...·op_0`, so iterate `ops` +/// in REVERSE (innermost conjugation by `op_last` first). +pub fn conjugate_pauli_by_deferred_ops( + flip_sites: &mut Vec, + sign_sites: &mut Vec, + phase: &mut Complex64, + ops: &[DeferredOp], +) { + for op in ops.iter().rev() { + match *op { + DeferredOp::Cnot(c, t) => { + let has_x_c = flip_sites.contains(&c); + let has_z_t = sign_sites.contains(&t); + if has_x_c { + toggle(flip_sites, t); + } + if has_z_t { + toggle(sign_sites, c); + } + } + DeferredOp::H(q) => { + let has_x = flip_sites.contains(&q); + let has_z = sign_sites.contains(&q); + // Swap membership of q between flip and sign. + if has_x != has_z { + if has_x { + toggle(flip_sites, q); + toggle(sign_sites, q); + } else { + toggle(sign_sites, q); + toggle(flip_sites, q); + } + } + // If both: Y → -Y (H·Y·H = -Y). Membership stays. Phase flips. + if has_x && has_z { + *phase = -*phase; + } + } + DeferredOp::Cz(a, b) => { + let has_x_a = flip_sites.contains(&a); + let has_x_b = flip_sites.contains(&b); + if has_x_a { + toggle(sign_sites, b); + } + if has_x_b { + toggle(sign_sites, a); + } + } + DeferredOp::Z(q) => { + // Z·X_q·Z = -X_q. If X present at q (and Z not at q), phase flips. + // Z·Y_q·Z = -Y_q (Y has X factor). So if X present regardless of Z, phase flips. + // Z·Z_q·Z = Z_q. No flip if only Z at q. + if flip_sites.contains(&q) { + *phase = -*phase; + } + } + DeferredOp::SZdg(q) => { + // SZdg conjugation: SZdg†·P·SZdg = SZ·P·SZdg. + // SZ·X·SZdg = Y = iXZ; SZ·Z·SZdg = Z. + // If X at q and Z not at q: add q to sign, phase *= i. + // If X at q and Z at q: SZ·Y·SZdg = i·(SZ·X·SZdg)·(SZ·Z·SZdg) = i·Y·Z = i·(iXZ)·Z = -X. + // So XZ → X only (toggle z), phase *= i (aggregate: p · iXZ · Z = ip·X). + // Matrix sanity-check: SZ = [[1,0],[0,i]], SZdg = [[1,0],[0,-i]], + // Y = [[0,-i],[i,0]]. + // SZ·Y·SZdg = [[1,0],[0,i]]·[[0,-i],[i,0]]·[[1,0],[0,-i]] + // = [[0,-i],[-1,0]]·[[1,0],[0,-i]] + // = [[0, -1],[-1, 0]] = -X. ✓ + let has_x = flip_sites.contains(&q); + let has_z = sign_sites.contains(&q); + if has_x && !has_z { + // X only → XZ (add Z), phase *= i. + toggle(sign_sites, q); + *phase *= Complex64::new(0.0, 1.0); + } else if has_x && has_z { + // XZ → X only (remove Z), phase *= i. + toggle(sign_sites, q); + *phase *= Complex64::new(0.0, 1.0); + } + // Z only or none: unchanged. + } + DeferredOp::SZ(q) => { + // SZ conjugation: SZdg·P·SZ. + // SZdg·X·SZ = -Y = -i·X·Z; SZdg·Z·SZ = Z; SZdg·Y·SZ = X. + // X only → X·Z, phase *= -i. + // X·Z → X only, phase *= -i. + // Z only or none: unchanged. + let has_x = flip_sites.contains(&q); + if has_x { + toggle(sign_sites, q); + *phase *= Complex64::new(0.0, -1.0); + } + } + } + } +} + +/// Backwards-compatible CNOT-only conjugation wrapper. CNOT conjugation +/// doesn't touch phase, so this discards the phase output. +pub fn conjugate_pauli_by_deferred( + flip_sites: &mut Vec, + sign_sites: &mut Vec, + cnots: &[(usize, usize)], +) { + let ops: Vec = cnots.iter().map(|&(c, t)| DeferredOp::Cnot(c, t)).collect(); + let mut phase = Complex64::new(1.0, 0.0); + conjugate_pauli_by_deferred_ops(flip_sites, sign_sites, &mut phase, &ops); +} + +/// Apply the deferred op queue `V = ops[last]·...·ops[0]` to `mps` and clear. +/// +/// # Panics +/// +/// Panics if any MPS gate application fails on a valid site. +pub fn flush_deferred_ops(mps: &mut Mps, ops: &mut Vec) { + let h_gate = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(-std::f64::consts::FRAC_1_SQRT_2, 0.0), + ], + ); + let cz_diag = [ + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(-1.0, 0.0), + ]; + for op in ops.iter() { + match *op { + DeferredOp::Cnot(c, t) => apply_cnot_to_mps(mps, c, t), + DeferredOp::H(q) => { + mps.apply_one_site_gate(q, &h_gate) + .expect("MPS op on valid site"); + } + DeferredOp::Cz(a, b) => { + // CZ is diagonal; use apply_two_site_gate (adjacent) or + // long-range two-site (non-adjacent). Either preserves bond + // dim since it's diagonal in the product basis. + let (q0, q1) = if a < b { (a, b) } else { (b, a) }; + let o = Complex64::new(0.0, 0.0); + let cz = DMatrix::from_row_slice( + 4, + 4, + &[ + cz_diag[0], o, o, o, o, cz_diag[1], o, o, o, o, cz_diag[2], o, o, o, o, + cz_diag[3], + ], + ); + if q1 == q0 + 1 { + mps.apply_two_site_gate(q0, &cz) + .expect("MPS op on valid site"); + } else { + mps.apply_long_range_two_site_gate(q0, q1, &cz) + .expect("MPS op on valid site"); + } + } + DeferredOp::Z(q) => { + let z_diag = [Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)]; + mps.apply_diagonal_one_site(q, &z_diag) + .expect("MPS op on valid site"); + } + DeferredOp::SZdg(q) => { + let sdg_diag = [Complex64::new(1.0, 0.0), Complex64::new(0.0, -1.0)]; + mps.apply_diagonal_one_site(q, &sdg_diag) + .expect("MPS op on valid site"); + } + DeferredOp::SZ(q) => { + let s_diag = [Complex64::new(1.0, 0.0), Complex64::new(0.0, 1.0)]; + mps.apply_diagonal_one_site(q, &s_diag) + .expect("MPS op on valid site"); + } + } + } + ops.clear(); +} + +/// Backwards-compatible CNOT-only flush wrapper. +pub fn flush_deferred(mps: &mut Mps, cnots: &mut Vec<(usize, usize)>) { + let mut ops: Vec = cnots.iter().map(|&(c, t)| DeferredOp::Cnot(c, t)).collect(); + flush_deferred_ops(mps, &mut ops); + cnots.clear(); +} + +/// Returns true if `mps` tensor at `site` has the σ=`block`'s elements all +/// below tolerance (i.e., site has no amplitude at that physical dim value). +fn mps_site_block_is_zero(mps: &Mps, site: usize, block: usize) -> bool { + let chi_r = mps.bond_dim(site + 1); + let t = &mps.tensors()[site]; + let start_col = block * chi_r; + for i in 0..t.nrows() { + for j in 0..chi_r { + if t[(i, start_col + j)].norm_sqr() > 1e-20 { + return false; + } + } + } + true +} + +/// Project qubit `q_idx` onto `outcome` without renormalizing. Returns +/// `false` if the projection is to a zero-probability outcome. +/// +/// Unlike `project_forced_z`, the MPS is left UNNORMALIZED: its norm drops +/// by `sqrt(conditional_prob)` after this call. This is what lets the caller +/// recover the complex amplitude at the end via `mps.amplitude(&[0;N])`. +/// +/// Used by `StabMps::amplitude_iterative` (Liu-Clark VI.B). +/// +/// # Panics +/// +/// Panics if any MPS gate application fails on a valid site. +pub fn project_forced_z_unnormalized( + tableau: &mut SparseStabY, + mps: &mut Mps, + q_idx: usize, + outcome: bool, +) -> bool { + // Trivial MPS: just consult the tableau. + if is_mps_trivial(mps) { + let decomp = decompose_z(tableau.stabs(), tableau.destabs(), q_idx); + let ok = match decomp { + ZDecomposition::Stabilizer { phase, .. } => { + let det_outcome = phase.re < 0.0; + det_outcome == outcome + } + ZDecomposition::DestabilizerFlip { .. } => { + // MPS is trivial (|0⟩^N scaled); both outcomes contribute + // amplitude 1/sqrt(2). Apply the equal-sum projection by + // rescaling the (already trivial) MPS by 1/sqrt(2) on site + // 0 to preserve probability normalization. + mps.scale(Complex64::new(1.0 / std::f64::consts::SQRT_2, 0.0)); + true + } + }; + if ok { + tableau.mz_forced(q_idx, outcome); + } + return ok; + } + + pre_reduce_for_measurement(tableau, mps, q_idx, true); + let decomp = decompose_z(tableau.stabs(), tableau.destabs(), q_idx); + + match decomp { + ZDecomposition::Stabilizer { phase, sign_sites } => { + if sign_sites.is_empty() { + let det_outcome = phase.re < 0.0; + if det_outcome != outcome { + return false; + } + tableau.mz_forced(q_idx, outcome); + return true; + } + let sign_f = if outcome { -1.0 } else { 1.0 }; + let z_diag = [Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)]; + let mut mps_z = mps.clone(); + for &k in &sign_sites { + mps_z + .apply_diagonal_one_site(k, &z_diag) + .expect("MPS op on valid site"); + } + mps_z.scale(Complex64::new(sign_f, 0.0) * phase * Complex64::new(0.5, 0.0)); + mps.scale(Complex64::new(0.5, 0.0)); + *mps = mps.add(&mps_z); + mps.compress(); + tableau.mz_forced(q_idx, outcome); + true + } + + ZDecomposition::DestabilizerFlip { + flip_sites, + phase, + sign_sites, + } => { + let sign_f = if outcome { -1.0 } else { 1.0 }; + if flip_sites.len() == 1 && sign_sites.is_empty() { + let k = flip_sites[0]; + let chi_r = mps.bond_dim(k + 1); + let sp = Complex64::new(sign_f, 0.0) * phase; + let block_0 = crate::mps::tensor::phys_block(&mps.tensors()[k], 0, chi_r); + let block_1 = crate::mps::tensor::phys_block(&mps.tensors()[k], 1, chi_r); + // Project onto (I + sp·X_k)/2 eigenstate, then basis-change + // (X_k → Z_k via mz_forced). The projected state has σ_0 = σ_1; + // collapsing to the new Z=0 eigenstate keeps norm via √2 factor. + let inv_sqrt2 = Complex64::new(1.0 / std::f64::consts::SQRT_2, 0.0); + let projected = (&block_0 + &block_1 * sp) * inv_sqrt2; + let zero = DMatrix::zeros(mps.tensors()[k].nrows(), chi_r); + crate::mps::tensor::set_phys_block(&mut mps.tensors_mut()[k], 0, chi_r, &projected); + crate::mps::tensor::set_phys_block(&mut mps.tensors_mut()[k], 1, chi_r, &zero); + } else { + let x_gate = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let z_diag = [Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)]; + let mut mps_z = mps.clone(); + // Apply Z first, then X (order must match z_expectation_value). + for &k in &sign_sites { + mps_z + .apply_diagonal_one_site(k, &z_diag) + .expect("MPS op on valid site"); + } + for &j in &flip_sites { + mps_z + .apply_one_site_gate(j, &x_gate) + .expect("MPS op on valid site"); + } + mps_z.scale(Complex64::new(sign_f, 0.0) * phase * Complex64::new(0.5, 0.0)); + mps.scale(Complex64::new(0.5, 0.0)); + *mps = mps.add(&mps_z); + mps.compress(); + if flip_sites.len() == 1 { + let k = flip_sites[0]; + let chi_r = mps.bond_dim(k + 1); + let zero = DMatrix::zeros(mps.tensors()[k].nrows(), chi_r); + crate::mps::tensor::set_phys_block(&mut mps.tensors_mut()[k], 1, chi_r, &zero); + // Basis swap at flip site: σ_0_new absorbs both σ_0 and σ_1 + // of old basis → √2 factor to preserve norm. + mps.scale(Complex64::new(std::f64::consts::SQRT_2, 0.0)); + } + // For >1 flip sites, the multi-site projection distributes + // amplitude across sites in a way our simple basis-swap trick + // doesn't handle. Callers should pre-reduce the tableau + // (`pre_reduce_for_measurement`) to collapse to single-flip. + } + tableau.mz_forced(q_idx, outcome); + true + } + } +} + +/// Project qubit `q_idx` onto a forced Z-basis outcome and return the +/// probability of that outcome given the current state. +/// +/// Mirrors `measure_qubit_stab_mps` but deterministic: no RNG, the outcome is +/// supplied by the caller. Useful for bitstring-probability computation +/// (Liu-Clark 2412.17209 Algorithm 3 / VI.A). +/// +/// # Panics +/// +/// Panics if any MPS gate application fails on a valid site. +pub fn project_forced_z( + tableau: &mut SparseStabY, + mps: &mut Mps, + q_idx: usize, + outcome: bool, +) -> f64 { + if is_mps_trivial(mps) { + // Trivial MPS: delegate to tableau's deterministic/random path logic + // but force the outcome. The tableau tracks signs; for a deterministic + // result the probability is 1 if the outcome matches, 0 otherwise. + // For a random result probability is 0.5. + let decomp = decompose_z(tableau.stabs(), tableau.destabs(), q_idx); + let prob = match decomp { + ZDecomposition::Stabilizer { phase, .. } => { + let det_outcome = phase.re < 0.0; + if det_outcome == outcome { 1.0 } else { 0.0 } + } + ZDecomposition::DestabilizerFlip { .. } => 0.5, + }; + if prob > 0.0 { + tableau.mz_forced(q_idx, outcome); + } + return prob; + } + + pre_reduce_for_measurement(tableau, mps, q_idx, true); + let ev = z_expectation_value(tableau, mps, q_idx).re; + let decomp = decompose_z(tableau.stabs(), tableau.destabs(), q_idx); + + match decomp { + ZDecomposition::Stabilizer { phase, sign_sites } => { + if sign_sites.is_empty() { + let det_outcome = phase.re < 0.0; + if det_outcome == outcome { + tableau.mz_forced(q_idx, outcome); + return 1.0; + } + return 0.0; + } + let prob_plus = f64::midpoint(1.0, ev).clamp(0.0, 1.0); + let prob = if outcome { 1.0 - prob_plus } else { prob_plus }; + if prob < 1e-20 { + return 0.0; + } + let sign_f = if outcome { -1.0 } else { 1.0 }; + + let z_diag = [Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)]; + let mut mps_z = mps.clone(); + for &k in &sign_sites { + mps_z + .apply_diagonal_one_site(k, &z_diag) + .expect("MPS op on valid site"); + } + mps_z.scale( + Complex64::new(sign_f, 0.0) * phase + / Complex64::new(2.0 * prob.max(1e-20).sqrt(), 0.0), + ); + mps.scale(Complex64::new(1.0 / (2.0 * prob.max(1e-20).sqrt()), 0.0)); + *mps = mps.add(&mps_z); + mps.compress(); + tableau.mz_forced(q_idx, outcome); + prob + } + + ZDecomposition::DestabilizerFlip { + flip_sites, + phase, + sign_sites, + } => { + let prob_plus = f64::midpoint(1.0, ev).clamp(0.0, 1.0); + let prob = if outcome { 1.0 - prob_plus } else { prob_plus }; + if prob < 1e-20 { + return 0.0; + } + let sign_f = if outcome { -1.0 } else { 1.0 }; + + if flip_sites.len() == 1 && sign_sites.is_empty() { + let k = flip_sites[0]; + let chi_r = mps.bond_dim(k + 1); + let sp = Complex64::new(sign_f, 0.0) * phase; + let block_0 = crate::mps::tensor::phys_block(&mps.tensors()[k], 0, chi_r); + let block_1 = crate::mps::tensor::phys_block(&mps.tensors()[k], 1, chi_r); + let projected = (&block_0 + &block_1 * sp) + / Complex64::new((2.0 * prob).max(1e-20).sqrt(), 0.0); + let zero = DMatrix::zeros(mps.tensors()[k].nrows(), chi_r); + crate::mps::tensor::set_phys_block(&mut mps.tensors_mut()[k], 0, chi_r, &projected); + crate::mps::tensor::set_phys_block(&mut mps.tensors_mut()[k], 1, chi_r, &zero); + mps.normalize(); + } else { + let x_gate = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let z_diag = [Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)]; + let mut mps_z = mps.clone(); + // Order must match z_expectation_value: Z first, then X. + // At overlap sites, this yields XZ = Y-convention Y (not ZX + // = -Y_conv). Inconsistent order would project onto the + // opposite-sign operator, leaving state in wrong subspace. + for &k in &sign_sites { + mps_z + .apply_diagonal_one_site(k, &z_diag) + .expect("MPS op on valid site"); + } + for &j in &flip_sites { + mps_z + .apply_one_site_gate(j, &x_gate) + .expect("MPS op on valid site"); + } + mps_z.scale( + Complex64::new(sign_f, 0.0) * phase + / Complex64::new(2.0 * prob.max(1e-20).sqrt(), 0.0), + ); + mps.scale(Complex64::new(1.0 / (2.0 * prob.max(1e-20).sqrt()), 0.0)); + *mps = mps.add(&mps_z); + mps.compress(); + if flip_sites.len() == 1 { + let k = flip_sites[0]; + let chi_r = mps.bond_dim(k + 1); + let zero = DMatrix::zeros(mps.tensors()[k].nrows(), chi_r); + crate::mps::tensor::set_phys_block(&mut mps.tensors_mut()[k], 1, chi_r, &zero); + } + mps.normalize(); + } + + tableau.mz_forced(q_idx, outcome); + prob + } + } +} + +/// Measure qubit `q_idx` in the Z basis using the STN protocol. +/// +/// Uses the tableau for structure (stabilizer/destabilizer decomposition) +/// and the MPS for probability computation and projection. +/// Lazy-compensation measurement (V2): accumulates `pre_reduce` CNOTs AND +/// the post-projection `W⁻¹` (single-qubit H + diagonal CZs) into a +/// `DeferredOp` queue. Uses `V†`-conjugated Pauli for projection. State +/// invariant: `effective = C_tableau · V_deferred · stored_mps`. +/// +/// Derivation: +/// - After `pre_reduce` row ops, tableau's C -> C*A (A = product of CNOTs). +/// Push each CNOT to V: `V_new = A * V_old` (left-multiply). +/// - After projection `(I + sp*P)/2` in effective frame, stored MPS is +/// projected via conjugated `Q = V^dag * P * V`: `stored' = (I+sp*Q)/2*stored`. +/// - `mz_forced` updates tableau: C*A -> C*A*W where `W*Z_id*W^dag = P`. +/// To preserve `effective = C_tableau * V * stored`, absorb `W^-1` into +/// V: `V_new = W^-1 * V` (append `W^-1`'s primitives at end of queue). +/// - For single-flip `P = X_id * Z_{sign}`, `W = CZ(id, s_1)*...*CZ(id, s_k)*H_id` +/// and `W^-1 = H_id * CZ(id, s_1)*...*CZ(id, s_k)`. All cheap primitives +/// (single-site H, diagonal CZ). +/// +/// # Panics +/// +/// Panics if the tableau measurement iterator is empty (should not happen). +pub fn measure_qubit_stab_mps_lazy( + tableau: &mut SparseStabY, + mps: &mut Mps, + rng: &mut PecosRng, + q_idx: usize, + deferred: &mut Vec, +) -> MeasurementResult { + if is_mps_trivial(mps) { + return tableau + .mz(&[pecos_core::QubitId(q_idx)]) + .into_iter() + .next() + .expect("MPS op on valid site"); + } + + // Push pre_reduce CNOTs to deferred instead of applying eagerly. + { + let col_x = &tableau.stabs().col_x[q_idx]; + if col_x.len() > 1 { + let replaced_idx = find_replaced_stabilizer(tableau, q_idx); + let n = tableau.num_qubits(); + let anticom: Vec = tableau.stabs().col_x[q_idx] + .iter() + .filter(|&id| id != replaced_idx) + .collect(); + let stabs_snapshot = tableau.stabs().clone(); + let destabs_snapshot = tableau.destabs().clone(); + for other_id in anticom { + crate::stab_mps::tableau_compose::multiply_row( + tableau.stabs_mut(), + other_id, + &stabs_snapshot, + replaced_idx, + n, + ); + crate::stab_mps::tableau_compose::multiply_row( + tableau.destabs_mut(), + replaced_idx, + &destabs_snapshot, + other_id, + n, + ); + deferred.push(DeferredOp::Cnot(replaced_idx, other_id)); + } + } + } + + let decomp = decompose_z(tableau.stabs(), tableau.destabs(), q_idx); + match decomp { + ZDecomposition::Stabilizer { phase, sign_sites } => { + let mut flip_conj: Vec = Vec::new(); + let mut sign_conj: Vec = sign_sites; + let mut phase_conj = phase; + conjugate_pauli_by_deferred_ops( + &mut flip_conj, + &mut sign_conj, + &mut phase_conj, + deferred, + ); + + let ev = pauli_expectation(mps, &flip_conj, &sign_conj, phase_conj).re; + + if sign_conj.is_empty() && flip_conj.is_empty() { + let outcome = phase_conj.re < 0.0; + tableau.mz_forced(q_idx, outcome); + return MeasurementResult { + outcome, + is_deterministic: true, + }; + } + let prob_plus = f64::midpoint(1.0, ev).clamp(0.0, 1.0); + let is_determ = (ev.abs() - 1.0).abs() < 1e-6; + let outcome = if is_determ { + ev < 0.0 + } else { + rng.random_bool(1.0 - prob_plus) + }; + let sign_f = if outcome { -1.0 } else { 1.0 }; + let prob = if outcome { 1.0 - prob_plus } else { prob_plus }; + apply_pauli_projection(mps, &flip_conj, &sign_conj, phase_conj, sign_f, prob); + MeasurementResult { + outcome, + is_deterministic: is_determ, + } + } + ZDecomposition::DestabilizerFlip { + flip_sites, + phase, + sign_sites, + } => { + // Pre_reduce ensures flip_sites.len() == 1. Let id = flip_sites[0]. + // Mz_forced will transform tableau as C → C·W where + // W · Z_id · W† = X_id · Z_{sign_sites} + // (the decomposition's Pauli content, phase absorbed in sp). + // Valid W: CZ(id, s_1)·...·CZ(id, s_k) · H_id. + // To preserve invariant, V_new = W⁻¹ · V_old. W⁻¹ = H_id · CZ_chain + // (reversed product with self-adjoint primitives). + let id = if flip_sites.len() == 1 { + flip_sites[0] + } else { + // Shouldn't happen after pre_reduce; use first as fallback. + debug_assert!( + !flip_sites.is_empty(), + "lazy measure: flip_sites empty in DestabilizerFlip" + ); + flip_sites[0] + }; + + // Conjugate the PRE-basis-rotation Pauli by existing V†. + let mut flip_conj: Vec = flip_sites.clone(); + let mut sign_conj: Vec = sign_sites.clone(); + let mut phase_conj = phase; + conjugate_pauli_by_deferred_ops( + &mut flip_conj, + &mut sign_conj, + &mut phase_conj, + deferred, + ); + + let ev = pauli_expectation(mps, &flip_conj, &sign_conj, phase_conj).re; + let prob_plus = f64::midpoint(1.0, ev).clamp(0.0, 1.0); + let outcome = rng.random_bool(1.0 - prob_plus); + let sign_f = if outcome { -1.0 } else { 1.0 }; + let prob = if outcome { 1.0 - prob_plus } else { prob_plus }; + + // Project stored MPS via conjugated Pauli. + apply_pauli_projection(mps, &flip_conj, &sign_conj, phase_conj, sign_f, prob); + // Absorb W⁻¹ into V. W satisfies: + // W · Z_id · W† = sp · X_flip · Z_sign (MPS-frame post-measurement Pauli) + // where `sp = sign_f · phase_conj` (sign_f = -1 if outcome else +1). + // sp is one of {+1, -1, +i, -i}. Hermiticity of Z_id forces a + // dichotomy on `X_flip · Z_sign` (single flip = {id}): + // - id ∉ sign: X_id · Z_sign is Hermitian, sp must be real. + // - id ∈ sign: X_id · Z_id · Z_rest = -i·Y_id·Z_rest is + // anti-Hermitian, sp must be imaginary. + // + // Basis-rotation constructions (each giving W·Z_id·W† = target): + // Real sp, id ∉ sign: + // sp = +1: W = [CZ(id, s) for s∈sign] · H_id + // sp = -1: W = Z_id · [CZ(id, s) for s∈sign] · H_id + // Imaginary sp, id ∈ sign: + // sp = +i: W = [CZ(id, s) for s∈sign\id] · SZ_id · H_id + // sp = -i: W = [CZ(id, s) for s∈sign\id] · SZdg_id · H_id + // + // W⁻¹ reverses the product and adjoints each primitive. Deferred + // queue push order is application order (first-pushed applied + // first), which corresponds to rightmost-in-product. So push + // W⁻¹'s primitives right-to-left: + // + // W is determined by mz_forced's action on the CURRENT tableau + // (post-pre_reduce). Use the original decomposition `phase`, not + // the V-conjugated `phase_conj` — V-conjugation is for MPS + // operations only; the tableau sees the original decomposition. + let sp = Complex64::new(sign_f, 0.0) * phase; + let id_in_sign = sign_sites.contains(&id); + if sp.im.abs() < 1e-9 { + // Real sp branch. id must not be in sign. + debug_assert!( + !id_in_sign, + "lazy measure: real sp={sp:?} but id in sign (expected imaginary)" + ); + if sp.re < 0.0 { + deferred.push(DeferredOp::Z(id)); + } + for &s in &sign_sites { + if s != id { + deferred.push(DeferredOp::Cz(id, s)); + } + } + } else { + // Imaginary sp branch. id must be in sign. + debug_assert!( + id_in_sign, + "lazy measure: imaginary sp={sp:?} but id not in sign (expected real)" + ); + debug_assert!( + sp.re.abs() < 1e-9, + "lazy measure: sp={sp:?} not pure imaginary" + ); + for &s in &sign_sites { + if s != id { + deferred.push(DeferredOp::Cz(id, s)); + } + } + // W inner rotation: SZ for sp=+i, SZdg for sp=-i. + // W⁻¹'s corresponding primitive: SZdg for sp=+i, SZ for sp=-i. + if sp.im > 0.0 { + deferred.push(DeferredOp::SZdg(id)); + } else { + deferred.push(DeferredOp::SZ(id)); + } + } + deferred.push(DeferredOp::H(id)); + + tableau.mz_forced(q_idx, outcome); + MeasurementResult { + outcome, + is_deterministic: false, + } + } + } +} + +/// Apply projection `(I + sign_f · phase · X_flip · Z_sign) / 2` to `mps`, +/// normalized by `1/√prob`. Uses MPS addition; no site-collapse step +/// (caller is responsible for collapse if exact state needed). +fn apply_pauli_projection( + mps: &mut Mps, + flip_sites: &[usize], + sign_sites: &[usize], + phase: Complex64, + sign_f: f64, + prob: f64, +) { + let x_gate = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let z_diag = [Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)]; + let denom = Complex64::new(2.0 * prob.max(1e-20).sqrt(), 0.0); + if flip_sites.is_empty() && sign_sites.is_empty() { + mps.scale(Complex64::new(1.0, 0.0) + Complex64::new(sign_f, 0.0) * phase); + mps.scale(Complex64::new(1.0, 0.0) / denom); + return; + } + let mut mps_z = mps.clone(); + for &k in sign_sites { + mps_z + .apply_diagonal_one_site(k, &z_diag) + .expect("MPS op on valid site"); + } + for &j in flip_sites { + mps_z + .apply_one_site_gate(j, &x_gate) + .expect("MPS op on valid site"); + } + mps_z.scale(Complex64::new(sign_f, 0.0) * phase / denom); + mps.scale(Complex64::new(1.0, 0.0) / denom); + *mps = mps.add(&mps_z); + mps.compress(); +} + +/// Measure qubit `q_idx` in the Z basis using the STN protocol. +/// +/// # Panics +/// +/// Panics if the tableau measurement iterator is empty (should not happen). +pub fn measure_qubit_stab_mps( + tableau: &mut SparseStabY, + mps: &mut Mps, + rng: &mut PecosRng, + q_idx: usize, +) -> MeasurementResult { + // Trivial MPS: delegate to tableau + if is_mps_trivial(mps) { + return tableau + .mz(&[pecos_core::QubitId(q_idx)]) + .into_iter() + .next() + .expect("MPS op on valid site"); + } + + // Pre-reduce the tableau so that Z_q has at most one anticommuting stabilizer. + // This avoids the problematic multi-flip projection path. + // + // MPS compensation is intentionally SKIPPED here (`false`). Random + // measurement doesn't require exact (tableau, mps) consistency — the + // sampled outcome statistics and subsequent measurement stats remain + // self-consistent (same row ops happen in both forward and reverse + // comparisons). Compensation would trigger O(N) long-range CNOTs per + // measurement (SWAP chain -> exponential bond growth in MAST's + // measurement-heavy workload). Exact-state paths + // (`project_forced_z`, `project_forced_z_unnormalized`) pass `true`. + pre_reduce_for_measurement(tableau, mps, q_idx, false); + + // Compute the expectation value + let ev = z_expectation_value(tableau, mps, q_idx).re; + + let decomp = decompose_z(tableau.stabs(), tableau.destabs(), q_idx); + + match decomp { + ZDecomposition::Stabilizer { phase, sign_sites } => { + // Z_q is in the stabilizer group: measurement is deterministic. + if sign_sites.is_empty() { + let outcome = phase.re < 0.0; + tableau.mz_forced(q_idx, outcome); + return MeasurementResult { + outcome, + is_deterministic: true, + }; + } + let prob_plus = f64::midpoint(1.0, ev).clamp(0.0, 1.0); + + // Check if measurement is deterministic (ev ≈ ±1) + let is_determ = (ev.abs() - 1.0).abs() < 1e-6; + let outcome = if is_determ { + ev < 0.0 + } else { + rng.random_bool(1.0 - prob_plus) + }; + + let sign_f = if outcome { -1.0 } else { 1.0 }; + let prob = if outcome { 1.0 - prob_plus } else { prob_plus }; + + let z_diag = [Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)]; + let mut mps_z = mps.clone(); + for &k in &sign_sites { + mps_z + .apply_diagonal_one_site(k, &z_diag) + .expect("MPS op on valid site"); + } + mps_z.scale( + Complex64::new(sign_f, 0.0) * phase + / Complex64::new(2.0 * prob.max(1e-20).sqrt(), 0.0), + ); + mps.scale(Complex64::new(1.0 / (2.0 * prob.max(1e-20).sqrt()), 0.0)); + *mps = mps.add(&mps_z); + mps.compress(); + + tableau.mz_forced(q_idx, outcome); + MeasurementResult { + outcome, + is_deterministic: is_determ, + } + } + + ZDecomposition::DestabilizerFlip { + flip_sites, + phase, + sign_sites, + } => { + let prob_plus = f64::midpoint(1.0, ev).clamp(0.0, 1.0); + let outcome = rng.random_bool(1.0 - prob_plus); + let prob = if outcome { 1.0 - prob_plus } else { prob_plus }; + + if flip_sites.len() == 1 && sign_sites.is_empty() { + // Single flip at site k. Project to eigenstate of phase*X_k. + // After mz_forced: the projected state always goes to σ=0, + // because mz_forced encodes the outcome in the stabilizer sign. + let k = flip_sites[0]; + let chi_r = mps.bond_dim(k + 1); + let sign_f = if outcome { -1.0 } else { 1.0 }; + let sp = Complex64::new(sign_f, 0.0) * phase; + + let block_0 = crate::mps::tensor::phys_block(&mps.tensors()[k], 0, chi_r); + let block_1 = crate::mps::tensor::phys_block(&mps.tensors()[k], 1, chi_r); + let projected = (&block_0 + &block_1 * sp) + / Complex64::new((2.0 * prob).max(1e-20).sqrt(), 0.0); + + let zero = DMatrix::zeros(mps.tensors()[k].nrows(), chi_r); + crate::mps::tensor::set_phys_block(&mut mps.tensors_mut()[k], 0, chi_r, &projected); + crate::mps::tensor::set_phys_block(&mut mps.tensors_mut()[k], 1, chi_r, &zero); + mps.normalize(); + } else { + // Multi-site case with sign_sites: use MPS addition then collapse flip site. + let sign_f = if outcome { -1.0 } else { 1.0 }; + let x_gate = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let z_diag = [Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)]; + + let mut mps_z = mps.clone(); + // Apply Z first, then X (order must match z_expectation_value). + for &k in &sign_sites { + mps_z + .apply_diagonal_one_site(k, &z_diag) + .expect("MPS op on valid site"); + } + for &j in &flip_sites { + mps_z + .apply_one_site_gate(j, &x_gate) + .expect("MPS op on valid site"); + } + mps_z.scale( + Complex64::new(sign_f, 0.0) * phase + / Complex64::new(2.0 * prob.max(1e-20).sqrt(), 0.0), + ); + mps.scale(Complex64::new(1.0 / (2.0 * prob.max(1e-20).sqrt()), 0.0)); + *mps = mps.add(&mps_z); + mps.compress(); + + // Collapse the flip site to σ=0. After the MPS addition projector, + // block_1 = sp * block_0 (eigenstate condition). After mz_forced, + // σ=0 is the stabilizer eigenstate. Just zero out σ=1 and renormalize. + if flip_sites.len() == 1 { + let k = flip_sites[0]; + let chi_r = mps.bond_dim(k + 1); + let zero = DMatrix::zeros(mps.tensors()[k].nrows(), chi_r); + crate::mps::tensor::set_phys_block(&mut mps.tensors_mut()[k], 1, chi_r, &zero); + } + + mps.normalize(); + } + + tableau.mz_forced(q_idx, outcome); + MeasurementResult { + outcome, + is_deterministic: false, + } + } + } +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::mps::MpsConfig; + + fn sort_dedup(v: &mut Vec) { + v.sort_unstable(); + v.dedup(); + } + + #[test] + fn conjugate_single_cnot_x_on_control() { + // V = CNOT(0,1). V†·X_0·V = X_0·X_1. + let mut flip = vec![0]; + let mut sign: Vec = vec![]; + conjugate_pauli_by_deferred(&mut flip, &mut sign, &[(0, 1)]); + sort_dedup(&mut flip); + assert_eq!(flip, vec![0, 1]); + assert!(sign.is_empty()); + } + + #[test] + fn conjugate_single_cnot_z_on_target() { + // V = CNOT(0,1). V†·Z_1·V = Z_0·Z_1. + let mut flip: Vec = vec![]; + let mut sign = vec![1]; + conjugate_pauli_by_deferred(&mut flip, &mut sign, &[(0, 1)]); + sort_dedup(&mut sign); + assert!(flip.is_empty()); + assert_eq!(sign, vec![0, 1]); + } + + #[test] + fn conjugate_cnot_x_on_target_unchanged() { + // V = CNOT(0,1). V†·X_1·V = X_1 (target X unchanged). + let mut flip = vec![1]; + let mut sign: Vec = vec![]; + conjugate_pauli_by_deferred(&mut flip, &mut sign, &[(0, 1)]); + assert_eq!(flip, vec![1]); + assert!(sign.is_empty()); + } + + #[test] + fn conjugate_cnot_z_on_control_unchanged() { + // V = CNOT(0,1). V†·Z_0·V = Z_0 (control Z unchanged). + let mut flip: Vec = vec![]; + let mut sign = vec![0]; + conjugate_pauli_by_deferred(&mut flip, &mut sign, &[(0, 1)]); + assert!(flip.is_empty()); + assert_eq!(sign, vec![0]); + } + + #[test] + fn conjugate_two_cnots_cancels() { + // V = CNOT(0,1)·CNOT(0,1) = I. V†·X_0·V = X_0. + let mut flip = vec![0]; + let mut sign: Vec = vec![]; + conjugate_pauli_by_deferred(&mut flip, &mut sign, &[(0, 1), (0, 1)]); + sort_dedup(&mut flip); + assert_eq!(flip, vec![0]); + } + + #[test] + fn conjugate_cnot_chain_fanout() { + // V = CNOT(0,3)·CNOT(0,2)·CNOT(0,1) — fan-out from qubit 0. + // V†·X_0·V = ? Chain conjugation: innermost first. + // Step 1 (CNOT(0,3)): X_0 -> X_0·X_3. flip={0,3}. + // Step 2 (CNOT(0,2)): X_0 -> X_0·X_2. flip={0,2,3}. + // Step 3 (CNOT(0,1)): X_0 -> X_0·X_1. flip={0,1,2,3}. + let mut flip = vec![0]; + let mut sign: Vec = vec![]; + // Pushed in chronological order: first pushed = CNOT(0,1). + // V = last·...·first = CNOT(0,3)·CNOT(0,2)·CNOT(0,1). + conjugate_pauli_by_deferred(&mut flip, &mut sign, &[(0, 1), (0, 2), (0, 3)]); + sort_dedup(&mut flip); + assert_eq!(flip, vec![0, 1, 2, 3]); + assert!(sign.is_empty()); + } + + #[test] + fn flush_deferred_matches_eager() { + // Two MPS: one where we apply CNOTs eagerly, one where we flush + // the queue at the end. Final states should agree. + let config = MpsConfig::default(); + let num_qubits = 4; + + let mut mps_eager = Mps::new(num_qubits, config.clone()); + // Put into a non-trivial state first: apply H on site 0 via + // single-site gate (to avoid bond-dim 1 trivial case). + let h = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.5_f64.sqrt(), 0.0), + Complex64::new(0.5_f64.sqrt(), 0.0), + Complex64::new(0.5_f64.sqrt(), 0.0), + Complex64::new(-0.5_f64.sqrt(), 0.0), + ], + ); + mps_eager + .apply_one_site_gate(0, &h) + .expect("MPS op on valid site"); + let mut mps_lazy = mps_eager.clone(); + + // Apply CNOT(0,1), CNOT(0,2), CNOT(1,3) eagerly. + let cnots = vec![(0usize, 1usize), (0, 2), (1, 3)]; + for &(c, t) in &cnots { + apply_cnot_to_mps(&mut mps_eager, c, t); + } + + // Flush the same CNOTs. + let mut queue = cnots; + flush_deferred(&mut mps_lazy, &mut queue); + assert!(queue.is_empty()); + + // Compare state vectors. + let sv_e = mps_eager.state_vector(); + let sv_l = mps_lazy.state_vector(); + assert_eq!(sv_e.len(), sv_l.len()); + for (a, b) in sv_e.iter().zip(sv_l.iter()) { + assert!((a - b).norm() < 1e-10, "eager vs lazy differ: {a} vs {b}"); + } + } +} diff --git a/exp/pecos-stab-tn/src/stab_mps/non_clifford.rs b/exp/pecos-stab-tn/src/stab_mps/non_clifford.rs new file mode 100644 index 000000000..935d021fa --- /dev/null +++ b/exp/pecos-stab-tn/src/stab_mps/non_clifford.rs @@ -0,0 +1,605 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Non-Clifford gate protocol for the STN simulator. +//! +//! Applies RZ(theta) on the MPS using the rotation decomposition approach +//! from the stabilizer-TN reference implementation. Single-site cases use +//! direct 2x2 gates. Multi-site cases use either MPS addition (for all-X +//! or all-Z Pauli strings) or CNOT cascade + RX rotation + basis changes +//! (for mixed Pauli strings with Y overlaps). +//! +//! References: +//! - Masot-Llima, Garcia-Saez. arXiv:2403.08724 (STN protocol). +//! - Reference code: stabilizer-TN `update_xvec` and `apply_xvec_rot`. + +use super::pauli_decomp::{ZDecomposition, decompose_z}; +use crate::mps::Mps; +use nalgebra::DMatrix; +use num_complex::Complex64; +use pecos_simulators::SparseStabY; + +fn z_diag() -> [Complex64; 2] { + [Complex64::new(1.0, 0.0), Complex64::new(-1.0, 0.0)] +} + +// Cached gate matrices — allocated once per thread, reused across calls. +use std::cell::RefCell; +use std::collections::HashMap; + +thread_local! { + static GATE_CACHE: RefCell>> = RefCell::new(HashMap::new()); +} + +fn cached_gate(name: &'static str, init: impl FnOnce() -> DMatrix) -> DMatrix { + GATE_CACHE.with(|cache| { + cache.borrow_mut().entry(name).or_insert_with(init).clone() + }) +} + +fn x_gate_matrix() -> DMatrix { + cached_gate("X", || { + let o = Complex64::new(0.0, 0.0); + let one = Complex64::new(1.0, 0.0); + DMatrix::from_row_slice(2, 2, &[o, one, one, o]) + }) +} + +fn xz_gate_matrix() -> DMatrix { + cached_gate("XZ", || { + let o = Complex64::new(0.0, 0.0); + let one = Complex64::new(1.0, 0.0); + DMatrix::from_row_slice(2, 2, &[o, -one, one, o]) + }) +} + +fn z_gate_matrix() -> DMatrix { + cached_gate("Z", || { + let o = Complex64::new(0.0, 0.0); + let one = Complex64::new(1.0, 0.0); + DMatrix::from_row_slice(2, 2, &[one, o, o, -one]) + }) +} + +fn s_gate() -> DMatrix { + cached_gate("S", || { + DMatrix::from_row_slice( + 2, 2, + &[ + Complex64::new(1.0, 0.0), Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), Complex64::new(0.0, 1.0), + ], + ) + }) +} + +fn sdg_gate() -> DMatrix { + cached_gate("Sdg", || { + DMatrix::from_row_slice( + 2, 2, + &[ + Complex64::new(1.0, 0.0), Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), Complex64::new(0.0, -1.0), + ], + ) + }) +} + +fn rx_gate(theta: f64) -> DMatrix { + // RX depends on theta — can't cache. But the bd=1 fast path + // reads elements directly, so allocation is only for bd>1. + let half = theta / 2.0; + let c = Complex64::new(half.cos(), 0.0); + let s = Complex64::new(0.0, -half.sin()); + DMatrix::from_row_slice(2, 2, &[c, s, s, c]) +} + +fn cnot_lo_gate() -> DMatrix { + cached_gate("CX_lo", || { + let o = Complex64::new(0.0, 0.0); + let one = Complex64::new(1.0, 0.0); + DMatrix::from_row_slice( + 4, 4, + &[one, o, o, o, o, one, o, o, o, o, o, one, o, o, one, o], + ) + }) +} + +fn cnot_hi_gate() -> DMatrix { + cached_gate("CX_hi", || { + let o = Complex64::new(0.0, 0.0); + let one = Complex64::new(1.0, 0.0); + DMatrix::from_row_slice( + 4, 4, + &[one, o, o, o, o, o, o, one, o, o, one, o, o, one, o, o], + ) + }) +} + +/// CNOT with first qubit (lower index) as control. +/// Per-site Pauli type for the rotation decomposition. +#[derive(Clone, Copy, Debug, PartialEq)] +enum PauliType { + X, + Z, + Y, // Both flip AND sign on the same site. In Y convention: Y = iXZ (Hermitian). +} + +/// Mutable context carried alongside the rotation decomposition. +pub struct RzContext<'a> { + /// Per-site disentangling eigenstate flags. + pub disent_flags: &'a mut [Option], + /// GF(2) flip matrix for OFD diagnostics. + pub gf2_matrix: &'a mut super::ofd::Gf2FlipMatrix, + /// Running statistics for the STN simulator. + pub stats: &'a mut super::StabMpsStats, +} + +/// Apply RZ(theta) on qubit q using the rotation decomposition. +/// +/// Ported from stabilizer-TN's `update_xvec` and `apply_xvec_rot`. +/// Takes &mut tableau because the disentangle path composes compensating +/// Cliffords via right-composition. +/// +/// # Panics +/// +/// Panics if any MPS gate application fails on a valid site. +pub fn apply_rz_stab_mps( + tableau: &mut SparseStabY, + mps: &mut Mps, + cos_half: f64, + sin_half: f64, + q: usize, + normalize: bool, + ctx: &mut RzContext<'_>, +) { + let RzContext { + disent_flags, + gf2_matrix, + stats, + } = ctx; + stats.total_nonclifford += 1; + let decomp = decompose_z(tableau.stabs(), tableau.destabs(), q); + + // OFD diagnostic: check whether this gate's flip pattern is in the span + // of previously-recorded patterns. OFD says such gates can be implemented + // without bond-dim growth (using already-tracked flip structure). + // We also capture this BEFORE the branch decisions for cross-tab stats. + let is_ofd_in_span = if let ZDecomposition::DestabilizerFlip { ref flip_sites, .. } = decomp { + let flip_vec: Vec = flip_sites.clone(); + let in_span = gf2_matrix.is_in_span(&flip_vec); + if in_span { + stats.ofd_in_span += 1; + } else { + stats.ofd_new_dim += 1; + } + in_span + } else { + false + }; + + match decomp { + ZDecomposition::Stabilizer { + phase, + ref sign_sites, + } => { + stats.stabilizer += 1; + if sign_sites.is_empty() { + let scalar = Complex64::new(cos_half, 0.0) - Complex64::new(0.0, sin_half) * phase; + mps.scale(scalar); + // Scalar multiply doesn't modify site states -- flags unchanged. + } else if sign_sites.len() == 1 { + let k = sign_sites[0]; + let c0 = Complex64::new(cos_half, 0.0) - Complex64::new(0.0, sin_half) * phase; + let c1 = Complex64::new(cos_half, 0.0) + Complex64::new(0.0, sin_half) * phase; + mps.apply_diagonal_one_site(k, &[c0, c1]) + .expect("sign_site should be valid"); + disent_flags[k] = None; + } else { + // Multi-site Z diagonal via MPS addition (exact, no SVD until compress). + let mut mps_z = mps.clone(); + let zd = z_diag(); + for &j in sign_sites { + mps_z + .apply_diagonal_one_site(j, &zd) + .expect("MPS op on valid site"); + } + let scale2 = Complex64::new(0.0, -sin_half) * phase; + mps_z.scale(scale2); + mps.scale(Complex64::new(cos_half, 0.0)); + *mps = mps.add(&mps_z); + mps.compress(); + for &j in sign_sites { + disent_flags[j] = None; + } + } + } + + ZDecomposition::DestabilizerFlip { + ref flip_sites, + phase, + ref sign_sites, + } => { + // Build the per-site Pauli map (ind_dict in the reference). + // flip_sites -> X, sign_sites -> Z, both -> Y (= XZ = W) + let mut pauli_map: Vec<(usize, PauliType)> = Vec::new(); + for &j in flip_sites { + pauli_map.push((j, PauliType::X)); + } + for &k in sign_sites { + if let Some(entry) = pauli_map.iter_mut().find(|(s, _)| *s == k) { + entry.1 = PauliType::Y; // X + Z overlap -> Y (= W = XZ) + } else { + pauli_map.push((k, PauliType::Z)); + } + } + + let mut affected_sites: Vec = pauli_map.iter().map(|(s, _)| *s).collect(); + affected_sites.sort_unstable(); // Chain cascade requires sorted order + + if affected_sites.is_empty() { + return; + } + + // OFD disentangle check (Liu-Clark 2412.17209 Algorithm 1 Theorem 1): + // disentanglable iff some qubit i has MPS state |0⟩ AND P[i] ∈ {X, Y}. + // Our `disent_flags[i] = Some(Z(false))` means MPS is |0⟩ at i (fresh + // qubit never touched by a non-Clifford). We only ever have flags + // Z(false) or None after this session's semantic cleanup -- hence + // the simple check below. + let mut disent_site = None; + if affected_sites.len() > 1 { + for &(site, pt) in &pauli_map { + if matches!(pt, PauliType::X | PauliType::Y) + && matches!(disent_flags[site], Some(super::SiteEigenstate::Z(false))) + { + disent_site = Some(site); + break; + } + } + } + + if let Some(rot_site) = disent_site { + stats.multi_disent += 1; + if is_ofd_in_span { + stats.ofd_in_span_disent += 1; + } + // Record effective single-site flip pattern with rot_site metadata + gf2_matrix.add_row_with_meta(&[rot_site], super::ofd::RowMetadata { rot_site }); + + // Compute RX angle. Reference formula: + // co = -i*sin_half*phase * i^(Ys+1) + // After correction co should be real = ±sin(θ/2). + // We want RX(rx_angle)|0⟩ = cos(θ/2)|0⟩ - i·co·|1⟩, so + // rx_angle/2 must satisfy cos(rx_angle/2) = cos(θ/2) AND + // sin(rx_angle/2) = co. arcsin loses the cos sign for |θ/2| > π/2, + // so use the ±1 sign of co combined with the full angle θ. + let y_count = pauli_map.iter().filter(|(_, p)| *p == PauliType::Y).count(); + let mut co = Complex64::new(0.0, -sin_half) * phase; + let i_val = Complex64::new(0.0, 1.0); + let mut factor = Complex64::new(1.0, 0.0); + for _ in 0..=y_count { + factor *= i_val; + } + co *= factor; + debug_assert!( + co.im.abs() < 1e-8, + "co should be real after i^(Ys+1) correction: phase={phase}, Ys={y_count}, co={co}" + ); + // co = sin(θ/2) · s where s = ±1. Recover s from sign of co vs sin_half. + let rx_sign: f64 = if sin_half.abs() < 1e-12 + || (co.re - sin_half).abs() < (co.re + sin_half).abs() + { + 1.0 + } else { + -1.0 + }; + // Full angle: θ = 2·atan2(sin_half, cos_half). Use θ such that + // sin(rx_angle/2) matches co AND cos(rx_angle/2) = cos(θ/2). + // So rx_angle = s · θ. + let theta = 2.0 * sin_half.atan2(cos_half); + let rx_angle = rx_sign * theta; + + // Masot-Llima basis+CNOT pattern (inherited from stabilizer-TN + // reference). A direct CY/CZ "CP cascade" (Liu-Clark Algorithm 1) + // was attempted but produced subtle sign mismatches for rot_pt=Y + // cases driven by the phase pre-correction applied to rx_angle. + // Both patterns are mathematically equivalent; default is the + // tested one — keeping only it to avoid dual-path maintenance. + let rot_pt = pauli_map + .iter() + .find(|&&(s, _)| s == rot_site) + .expect("rot_site must be in pauli_map") + .1; + if matches!(rot_pt, PauliType::Y) { + mps.apply_one_site_gate(rot_site, &s_gate()) + .expect("MPS op on valid site"); + } + mps.apply_one_site_gate(rot_site, &rx_gate(rx_angle)) + .expect("MPS op on valid site"); + for &(site, pt) in &pauli_map { + match pt { + PauliType::Y => super::tableau_compose::right_compose_szdg(tableau, site), + PauliType::Z => super::tableau_compose::right_compose_h(tableau, site), + PauliType::X => {} + } + } + for &(other_site, _) in &pauli_map { + if other_site == rot_site { + continue; + } + super::tableau_compose::right_compose_cx(tableau, rot_site, other_site); + } + for &(site, pt) in &pauli_map { + if site == rot_site { + continue; + } + match pt { + PauliType::Y => super::tableau_compose::right_compose_sz(tableau, site), + PauliType::Z => super::tableau_compose::right_compose_h(tableau, site), + PauliType::X => {} + } + } + + // Clear the flag (rot_site's MPS is no longer |0⟩). + disent_flags[rot_site] = None; + } else if affected_sites.len() > 1 && is_ofd_in_span { + // OFD path: the flip pattern is in the GF(2) span of + // previously recorded patterns. Apply the disentangling + // Clifford to BOTH MPS and tableau simultaneously (which + // preserves the quantum state since the Clifford acts on + // both sides). Then apply the single-site non-Clifford RX + // on the MPS. This avoids the expensive MPS clone + add + + // compress cycle. + // + // For each right_compose_X on the tableau, we simultaneously + // apply X† on the MPS. The net effect of the matched pair is + // identity on the state — only the non-Clifford RX changes it. + stats.multi_disent += 1; + stats.ofd_in_span_disent += 1; + + let rot_site = pauli_map + .iter() + .find(|(_, pt)| matches!(pt, PauliType::X | PauliType::Y)) + .expect("DestabilizerFlip must have at least one X/Y site") + .0; + + gf2_matrix.add_row_with_meta(&[rot_site], super::ofd::RowMetadata { rot_site }); + + // Compute RX angle (same as disent path). + let y_count = pauli_map.iter().filter(|(_, p)| *p == PauliType::Y).count(); + let mut co = Complex64::new(0.0, -sin_half) * phase; + let i_val = Complex64::new(0.0, 1.0); + let mut factor = Complex64::new(1.0, 0.0); + for _ in 0..=y_count { + factor *= i_val; + } + co *= factor; + debug_assert!( + co.im.abs() < 1e-8, + "OFD: co should be real: phase={phase}, Ys={y_count}, co={co}" + ); + let rx_sign: f64 = if sin_half.abs() < 1e-12 + || (co.re - sin_half).abs() < (co.re + sin_half).abs() + { + 1.0 + } else { + -1.0 + }; + let theta = 2.0 * sin_half.atan2(cos_half); + let rx_angle = rx_sign * theta; + + // Basis changes: apply to both MPS (gate†) and tableau (right_compose). + // Use raw 2×2 arrays for MPS to avoid DMatrix allocation. + let zero = Complex64::new(0.0, 0.0); + let one = Complex64::new(1.0, 0.0); + let i_pos = Complex64::new(0.0, 1.0); + let i_neg = Complex64::new(0.0, -1.0); + let r2 = Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0); + + let s_raw = [[one, zero], [zero, i_pos]]; + let sdg_raw = [[one, zero], [zero, i_neg]]; + let h_raw = [[r2, r2], [r2, -r2]]; + + for &(site, pt) in &pauli_map { + match pt { + PauliType::Y => { + mps.apply_gate_2x2(site, s_raw); + super::tableau_compose::right_compose_szdg(tableau, site); + } + PauliType::Z => { + mps.apply_gate_2x2(site, h_raw); + super::tableau_compose::right_compose_h(tableau, site); + } + PauliType::X => {} + } + } + + // CNOT cascade: apply to both MPS and tableau. + let cx_lo = cnot_lo_gate(); + let cx_hi = cnot_hi_gate(); + for &(other_site, _) in &pauli_map { + if other_site == rot_site { + continue; + } + let (lo, hi) = (rot_site.min(other_site), rot_site.max(other_site)); + let gate = if rot_site < other_site { &cx_lo } else { &cx_hi }; + mps.apply_long_range_two_site_gate(lo, hi, gate) + .expect("CX should succeed on MPS"); + super::tableau_compose::right_compose_cx(tableau, rot_site, other_site); + } + + // Non-Clifford: RX at rot_site (MPS only). + let half = rx_angle / 2.0; + let rx_c = Complex64::new(half.cos(), 0.0); + let rx_s = Complex64::new(0.0, -half.sin()); + mps.apply_gate_2x2(rot_site, [[rx_c, rx_s], [rx_s, rx_c]]); + + // Undo basis changes at non-rot sites (MPS + tableau). + for &(site, pt) in &pauli_map { + if site == rot_site { + continue; + } + match pt { + PauliType::Y => { + mps.apply_gate_2x2(site, sdg_raw); + super::tableau_compose::right_compose_sz(tableau, site); + } + PauliType::Z => { + mps.apply_gate_2x2(site, h_raw); + super::tableau_compose::right_compose_h(tableau, site); + } + PauliType::X => {} + } + } + + // Compress: the CNOT cascade may have temporarily grown + // bond dim, but the undo basis changes partially restore it. + mps.compress(); + + disent_flags[rot_site] = None; + } else if affected_sites.len() == 1 { + stats.single_site += 1; + if is_ofd_in_span { + stats.ofd_in_span_single += 1; + } + // Record single-site flip pattern + gf2_matrix.add_row_with_meta( + &affected_sites, + super::ofd::RowMetadata { + rot_site: affected_sites[0], + }, + ); + let site = affected_sites[0]; + let pt = pauli_map[0].1; + let c = Complex64::new(cos_half, 0.0); + let s = Complex64::new(0.0, -sin_half) * phase; // = -i*sin*phase + + let gate = match pt { + PauliType::X => { + // X = [[0,1],[1,0]] + DMatrix::from_row_slice(2, 2, &[c, s, s, c]) + } + PauliType::Z => { + // Z = [[1,0],[0,-1]] + DMatrix::from_row_slice( + 2, + 2, + &[ + c + s, + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + c - s, + ], + ) + } + PauliType::Y => { + // co = -i·sin·phase · (-1) = i·sin·phase. Ys=1, factor=i^2=-1. + let mut co = Complex64::new(0.0, -sin_half) * phase; + co *= Complex64::new(-1.0, 0.0); + let rx_sign: f64 = if sin_half.abs() < 1e-12 + || (co.re - sin_half).abs() < (co.re + sin_half).abs() + { + 1.0 + } else { + -1.0 + }; + let theta = 2.0 * sin_half.atan2(cos_half); + let rx_angle = rx_sign * theta; + + &sdg_gate() * &(&rx_gate(rx_angle) * &s_gate()) + } + }; + mps.apply_one_site_gate(site, &gate) + .expect("MPS op on valid site"); + // Clear flag for the affected site + disent_flags[site] = None; + } else if sign_sites.is_empty() { + stats.multi_std += 1; + if is_ofd_in_span { + stats.ofd_in_span_std += 1; + } + // Note: std path creates MPS entanglement (not absorbed into + // tableau). Do NOT add to gf2 basis — OFD's is_in_span should + // only match against truly-absorbed rows. + // All flip sites, no Z overlap: operator is cos*I + s*prod(X_j). + // Use MPS addition (exact, no SWAP-chain SVD drift). + let cos = Complex64::new(cos_half, 0.0); + let s = Complex64::new(0.0, -sin_half) * phase; + let x_gate = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let mut mps_x = mps.clone(); + for &j in flip_sites { + mps_x + .apply_one_site_gate(j, &x_gate) + .expect("MPS op on valid site"); + } + mps_x.scale(s); + mps.scale(cos); + *mps = mps.add(&mps_x); + mps.compress(); + for &j in flip_sites { + disent_flags[j] = None; + } + } else { + stats.multi_std += 1; + if is_ofd_in_span { + stats.ofd_in_span_std += 1; + } + // Std path creates MPS entanglement; do NOT add to gf2 basis. + // Multi-site rotation via MPS addition instead of CNOT cascade. + // + // The decomposition tells us: Z_q = phase * P where P is a + // multi-site Pauli. The rotation exp(-i*θ/2 * Z_q) expands as: + // cos(θ/2)*I - i*sin(θ/2) * phase * P + // We compute cos*|ψ⟩ + s * P|ψ⟩ where s = -i*sin(θ/2)*phase, + // applying each per-site Pauli gate directly. + let cos = Complex64::new(cos_half, 0.0); + let s = Complex64::new(0.0, -sin_half) * phase; + + let mut mps_p = mps.clone(); + for &(site, pt) in &pauli_map { + let gate = match pt { + PauliType::X => x_gate_matrix(), + PauliType::Z => z_gate_matrix(), + PauliType::Y => xz_gate_matrix(), + }; + mps_p + .apply_one_site_gate(site, &gate) + .expect("MPS op on valid site"); + } + mps_p.scale(s); + mps.scale(cos); + *mps = mps.add(&mps_p); + mps.compress(); + for &site in &affected_sites { + disent_flags[site] = None; + } + } + } + } + + // Flags are cleared in each branch above, tracking which sites had MPS + // modifications. See branch-specific `disent_flags[...] = None` calls. + + if normalize { + mps.normalize(); + } +} diff --git a/exp/pecos-stab-tn/src/stab_mps/ofd.rs b/exp/pecos-stab-tn/src/stab_mps/ofd.rs new file mode 100644 index 000000000..13c4aa66c --- /dev/null +++ b/exp/pecos-stab-tn/src/stab_mps/ofd.rs @@ -0,0 +1,490 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! GF(2) diagnostics for Optimization-Free Disentangling (OFD). +//! +//! Tracks the binary "flip pattern" of each non-Clifford gate applied to the STN. +//! The GF(2) rank of the accumulated flip matrix gives the theoretical minimum +//! bond dimension achievable by Clifford disentangling: `bond_dim` = 2^(t - rank), +//! where t is the number of non-Clifford gates. +//! +//! Based on: Liu & Clark, "Classical simulability of Clifford+T circuits with +//! CAMPS," arXiv:2412.17209 (2024). + +/// Metadata associated with each non-Clifford gate tracked by the OFD matrix. +/// +/// For OFD's fix-up Clifford construction, we need to know which qubit each +/// gate acted on. This lets a later "`in_span`" gate construct its absorption +/// Clifford from combinations of earlier gates' contributions. +#[derive(Clone, Copy, Debug)] +pub struct RowMetadata { + /// The rotation axis qubit for the gate. For multi-site gates, this is + /// the chosen `rot_site`; for single-site, it's the affected site. + pub rot_site: usize, +} + +/// GF(2) matrix tracking flip patterns from non-Clifford gate decompositions. +/// +/// Each row is a binary vector of length `num_sites` (MPS sites). A 1 at position +/// j means the j-th destabilizer index was flipped (X or Y Pauli) in the +/// decomposition of `Z_q` for that non-Clifford gate. +/// +/// Rows are stored as `u128` bitmasks for allocation-free GF(2) operations. +/// Supports up to 128 MPS sites. +#[derive(Clone, Debug)] +pub struct Gf2FlipMatrix { + num_sites: usize, + /// Rows stored as u128 bitmasks. Bit j is set iff site j is flipped. + rows: Vec, + /// Metadata per row (parallel to `rows`). + metadata: Vec, +} + +impl Gf2FlipMatrix { + /// Create an empty matrix for `num_sites` MPS sites. + #[must_use] + pub fn new(num_sites: usize) -> Self { + Self { + num_sites, + rows: Vec::new(), + metadata: Vec::new(), + } + } + + /// Add a row from a non-Clifford gate's decomposition. + /// + /// `flip_sites` are the destabilizer indices that have X or Y in the + /// decomposition of `Z_q`. Metadata uses a default `rot_site` of 0 if not + /// otherwise known; prefer `add_row_with_meta` for OFD work. + pub fn add_row(&mut self, flip_sites: &[usize]) { + self.add_row_with_meta(flip_sites, RowMetadata { rot_site: 0 }); + } + + /// Add a row with explicit metadata for OFD fix-up construction. + pub fn add_row_with_meta(&mut self, flip_sites: &[usize], meta: RowMetadata) { + let mut row: u128 = 0; + for &site in flip_sites { + if site < self.num_sites && site < 128 { + row |= 1u128 << site; + } + } + self.rows.push(row); + self.metadata.push(meta); + } + + /// Metadata for row `i`, if it exists. + #[must_use] + pub fn row_metadata(&self, i: usize) -> Option { + self.metadata.get(i).copied() + } + + /// Number of non-Clifford gates tracked. + #[must_use] + pub fn num_gates(&self) -> usize { + self.rows.len() + } + + /// Compute the GF(2) rank via Gaussian elimination. + /// + /// Returns the rank (number of linearly independent rows over GF(2)). + #[must_use] + pub fn gf2_rank(&self) -> usize { + if self.rows.is_empty() { + return 0; + } + + let mut matrix: Vec = self.rows.clone(); + let num_rows = matrix.len(); + let cols = self.num_sites.min(128); + + let mut current_row = 0; + for col in 0..cols { + if current_row >= num_rows { + break; + } + let col_bit = 1u128 << col; + let found = matrix[current_row..] + .iter() + .position(|&row| row & col_bit != 0) + .map(|offset| current_row + offset); + if let Some(swap_row) = found { + matrix.swap(current_row, swap_row); + let pivot = matrix[current_row]; + for (r, row) in matrix.iter_mut().enumerate() { + if r != current_row && *row & col_bit != 0 { + *row ^= pivot; + } + } + current_row += 1; + } + } + current_row + } + + /// Theoretical minimum bond dimension achievable by Clifford disentangling. + /// + /// When all non-Clifford gates' flip patterns are linearly independent over + /// GF(2), each can be disentangled to a single site (bond dim stays 1). + /// When there are dependencies, each dependency doubles the bond dim. + /// + /// Returns `2^(num_gates - rank)`. + #[must_use] + pub fn theoretical_min_bond_dim(&self) -> usize { + let t = self.num_gates(); + let r = self.gf2_rank(); + if t <= r { 1 } else { 1 << (t - r) } + } + + /// Reset the matrix (e.g., after simulator reset). + pub fn reset(&mut self) { + self.rows.clear(); + self.metadata.clear(); + } + + /// Check whether a new flip row is in the span of already-added rows. + /// + /// Returns `true` if adding this row would NOT increase the GF(2) rank, + /// meaning the corresponding non-Clifford gate can be implemented using + /// flip patterns already tracked (zero bond-dim growth). + #[must_use] + pub fn is_in_span(&self, new_row: &[usize]) -> bool { + self.span_decomposition(new_row).is_some() + } + + /// Find the linear combination of existing rows whose XOR equals `new_row`. + /// + /// Returns `Some(indices)` if `new_row` is in the span, where `indices` + /// are original row indices whose XOR equals `new_row`. Returns `None` + /// if `new_row` is linearly independent (would grow rank). + /// + /// Uses u128 bitmasks for both data and provenance — zero heap allocation. + #[must_use] + pub fn span_decomposition(&self, new_row: &[usize]) -> Option> { + let num_rows = self.rows.len(); + if num_rows == 0 { + // Empty matrix: new_row is in span only if it's zero. + let mut target: u128 = 0; + for &s in new_row { + if s < self.num_sites && s < 128 { target |= 1u128 << s; } + } + return if target == 0 { Some(Vec::new()) } else { None }; + } + + // Augmented rows: (data bits, provenance bits). + // Provenance uses u128 bitmask — supports up to 64 accumulated rows. + // For larger matrices, fall back to Vec-based provenance. + if num_rows <= 128 { + return self.span_decomposition_fast(new_row); + } + + // Fallback for >64 rows (unlikely in practice) + self.span_decomposition_large(new_row) + } + + /// Fast span decomposition using u128 bitmasks for both data and provenance. + fn span_decomposition_fast(&self, new_row: &[usize]) -> Option> { + let num_rows = self.rows.len(); + + // Augmented: (data_bits, provenance_bits) — all stack-allocated. + let mut data: Vec = self.rows.clone(); + let mut prov: Vec = (0..num_rows).map(|i| 1u128 << i).collect(); + + // Gaussian elimination to RREF. + let cols = self.num_sites.min(128); + let mut current_row = 0; + for col in 0..cols { + if current_row >= num_rows { + break; + } + let col_bit = 1u128 << col; + let found = data[current_row..] + .iter() + .position(|&d| d & col_bit != 0) + .map(|offset| current_row + offset); + if let Some(sw) = found { + data.swap(current_row, sw); + prov.swap(current_row, sw); + let pivot_d = data[current_row]; + let pivot_p = prov[current_row]; + for r in 0..num_rows { + if r != current_row && data[r] & col_bit != 0 { + data[r] ^= pivot_d; + prov[r] ^= pivot_p; + } + } + current_row += 1; + } + } + + // Build target and reduce against RREF basis. + let mut v: u128 = 0; + for &s in new_row { + if s < self.num_sites && s < 128 { v |= 1u128 << s; } + } + let mut combination: u128 = 0; + + for i in 0..current_row { + let pivot = data[i].trailing_zeros() as usize; + if pivot < self.num_sites && v & (1u128 << pivot) != 0 { + v ^= data[i]; + combination ^= prov[i]; + } + } + + if v == 0 { + Some( + (0..num_rows) + .filter(|&i| combination & (1u128 << i) != 0) + .collect(), + ) + } else { + None + } + } + + /// Fallback span decomposition for >64 rows. + fn span_decomposition_large(&self, new_row: &[usize]) -> Option> { + let num_rows = self.rows.len(); + let mut data: Vec = self.rows.clone(); + let mut prov: Vec> = (0..num_rows) + .map(|i| { + let mut p = vec![false; num_rows]; + p[i] = true; + p + }) + .collect(); + + let cols = self.num_sites.min(128); + let mut current_row = 0; + for col in 0..cols { + if current_row >= num_rows { + break; + } + let col_bit = 1u128 << col; + let found = data[current_row..] + .iter() + .position(|&d| d & col_bit != 0) + .map(|offset| current_row + offset); + if let Some(sw) = found { + data.swap(current_row, sw); + prov.swap(current_row, sw); + let pivot_d = data[current_row]; + let pivot_p = prov[current_row].clone(); + for r in 0..num_rows { + if r != current_row && data[r] & col_bit != 0 { + data[r] ^= pivot_d; + for (c, &p) in prov[r].iter_mut().zip(pivot_p.iter()) { + *c ^= p; + } + } + } + current_row += 1; + } + } + + let mut v: u128 = 0; + for &s in new_row { + if s < self.num_sites && s < 128 { v |= 1u128 << s; } + } + let mut combination = vec![false; num_rows]; + for i in 0..current_row { + let pivot = data[i].trailing_zeros() as usize; + if pivot < self.num_sites && v & (1u128 << pivot) != 0 { + v ^= data[i]; + for (c, &p) in combination.iter_mut().zip(prov[i].iter()) { + *c ^= p; + } + } + } + + if v == 0 { + Some( + combination.iter().enumerate() + .filter_map(|(i, &b)| if b { Some(i) } else { None }) + .collect(), + ) + } else { + None + } + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_empty_matrix() { + let m = Gf2FlipMatrix::new(4); + assert_eq!(m.gf2_rank(), 0); + assert_eq!(m.theoretical_min_bond_dim(), 1); + } + + #[test] + fn test_single_row() { + let mut m = Gf2FlipMatrix::new(4); + m.add_row(&[0, 2]); // flip sites 0 and 2 + assert_eq!(m.gf2_rank(), 1); + assert_eq!(m.theoretical_min_bond_dim(), 1); // 2^(1-1) = 1 + } + + #[test] + fn test_two_independent_rows() { + let mut m = Gf2FlipMatrix::new(4); + m.add_row(&[0]); // [1,0,0,0] + m.add_row(&[1]); // [0,1,0,0] + assert_eq!(m.gf2_rank(), 2); + assert_eq!(m.theoretical_min_bond_dim(), 1); // 2^(2-2) = 1 + } + + #[test] + fn test_two_dependent_rows() { + let mut m = Gf2FlipMatrix::new(4); + m.add_row(&[0, 1]); // [1,1,0,0] + m.add_row(&[0, 1]); // [1,1,0,0] -- same row + assert_eq!(m.gf2_rank(), 1); + assert_eq!(m.theoretical_min_bond_dim(), 2); // 2^(2-1) = 2 + } + + #[test] + fn test_three_rows_one_dependent() { + let mut m = Gf2FlipMatrix::new(4); + m.add_row(&[0, 1]); // [1,1,0,0] + m.add_row(&[1, 2]); // [0,1,1,0] + m.add_row(&[0, 2]); // [1,0,1,0] = row1 XOR row2 + assert_eq!(m.gf2_rank(), 2); + assert_eq!(m.theoretical_min_bond_dim(), 2); // 2^(3-2) = 2 + } + + #[test] + fn test_full_rank_n_equals_t() { + // 4 independent rows in 4 columns = rank 4 + let mut m = Gf2FlipMatrix::new(4); + m.add_row(&[0]); + m.add_row(&[1]); + m.add_row(&[2]); + m.add_row(&[3]); + assert_eq!(m.gf2_rank(), 4); + assert_eq!(m.theoretical_min_bond_dim(), 1); + } + + #[test] + fn test_is_in_span_empty() { + let m = Gf2FlipMatrix::new(3); + // Empty basis -- only zero vector is in span. + assert!(m.is_in_span(&[])); // all-zero row is always in span (trivially) + assert!(!m.is_in_span(&[0])); + assert!(!m.is_in_span(&[1, 2])); + } + + #[test] + fn test_is_in_span_single_row() { + let mut m = Gf2FlipMatrix::new(3); + m.add_row(&[0]); // basis: {e_0} + assert!(m.is_in_span(&[0])); + assert!(!m.is_in_span(&[1])); + assert!(!m.is_in_span(&[0, 1])); // e_0 + e_1 not in span of {e_0} + } + + #[test] + fn test_is_in_span_dependency() { + let mut m = Gf2FlipMatrix::new(3); + m.add_row(&[0]); + m.add_row(&[1]); + // Now {e_0, e_1} basis. e_0 XOR e_1 = (1,1,0) is in span. + assert!(m.is_in_span(&[0, 1])); + // e_2 is NOT in span. + assert!(!m.is_in_span(&[2])); + // e_0 XOR e_1 XOR e_2 is NOT in span (needs e_2). + assert!(!m.is_in_span(&[0, 1, 2])); + } + + #[test] + fn test_span_decomposition_simple() { + let mut m = Gf2FlipMatrix::new(3); + m.add_row(&[0]); // row 0: e_0 + m.add_row(&[1]); // row 1: e_1 + // e_0 + e_1 = (1,1,0) should decompose to {0, 1}. + let dep = m.span_decomposition(&[0, 1]).expect("in span"); + assert_eq!(dep, vec![0, 1]); + // e_0 alone decomposes to {0}. + let dep = m.span_decomposition(&[0]).expect("in span"); + assert_eq!(dep, vec![0]); + // e_2 is not in span. + assert!(m.span_decomposition(&[2]).is_none()); + } + + #[test] + fn test_span_decomposition_verify_xor() { + // Property: the returned indices XOR to the input row. + let mut m = Gf2FlipMatrix::new(5); + m.add_row(&[0, 1]); + m.add_row(&[2, 3]); + m.add_row(&[1, 3, 4]); + m.add_row(&[0, 2, 4]); // Should be dependent: row0 XOR row1 XOR row2 = (1,1,0,0,0) XOR (0,0,1,1,0) XOR (0,1,0,1,1) = (1,0,1,0,1) + // Test that (1,0,1,0,1) decomposes properly. + let target = &[0, 2, 4]; + let dep = m.span_decomposition(target).expect("should be in span"); + // Verify the XOR reconstructs target. + let mut recon: u128 = 0; + for &i in &dep { + recon ^= m.rows[i]; + } + let mut target_bits: u128 = 0; + for &s in target { + target_bits |= 1u128 << s; + } + assert_eq!(recon, target_bits, "XOR of rows {dep:?} should equal target"); + } + + #[test] + fn test_is_in_span_matches_rank_check() { + // Property: is_in_span(row) iff adding row doesn't change rank. + let mut m = Gf2FlipMatrix::new(4); + m.add_row(&[0, 1]); + m.add_row(&[2, 3]); + m.add_row(&[0, 2]); + let rank_before = m.gf2_rank(); + for row in [ + vec![0], + vec![1], + vec![2], + vec![3], + vec![0, 1], + vec![1, 2], + vec![0, 1, 2, 3], + ] { + let in_span = m.is_in_span(&row); + let mut m2 = m.clone(); + m2.add_row(&row); + let rank_after = m2.gf2_rank(); + assert_eq!( + in_span, + rank_after == rank_before, + "row {row:?}: is_in_span={in_span} but rank {rank_before} -> {rank_after}" + ); + } + } + + #[test] + fn test_more_rows_than_cols() { + // 5 rows, 3 cols -> rank <= 3, so at least 2 dependencies + let mut m = Gf2FlipMatrix::new(3); + m.add_row(&[0]); + m.add_row(&[1]); + m.add_row(&[2]); + m.add_row(&[0, 1]); // dependent: row1 XOR row2 + m.add_row(&[1, 2]); // dependent: row2 XOR row3 + assert_eq!(m.gf2_rank(), 3); + assert_eq!(m.theoretical_min_bond_dim(), 4); // 2^(5-3) = 4 + } +} diff --git a/exp/pecos-stab-tn/src/stab_mps/pauli_decomp.rs b/exp/pecos-stab-tn/src/stab_mps/pauli_decomp.rs new file mode 100644 index 000000000..6b9d97e1e --- /dev/null +++ b/exp/pecos-stab-tn/src/stab_mps/pauli_decomp.rs @@ -0,0 +1,1019 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Decompose Pauli operators in the stabilizer/destabilizer basis. +//! +//! The stabilizer tableau defines a basis for the Pauli group. Given stabilizer +//! generators {`S_0`, ..., S_{N-1}} and destabilizer generators {`D_0`, ..., D_{N-1}} +//! where `D_i` anticommutes with `S_i` and commutes with all other `S_j`, any Pauli +//! operator P can be written as: +//! +//! ```text +//! P = phase * prod_i S_i^{s_i} * prod_j D_j^{d_j} +//! ``` +//! +//! For the STN simulator, we need to decompose `Z_q` (Z on qubit q) in this basis. +//! The decomposition determines how RZ(theta) acts on the MPS. +//! +//! Uses the Y-convention phase table (matching the stabilizer-TN reference and +//! PECOS `SparseStabY`), where (x=1, z=1) represents Y (Hermitian, Y²=I). +//! +//! Reference: stabilizer-TN `gate_decomposition` function. + +use num_complex::Complex64; +use pecos_core::IndexSet; +use pecos_simulators::GensGeneric; + +/// Single-qubit Pauli kind for `decompose_pauli_string`. +#[derive(Clone, Copy, Debug, PartialEq, Eq)] +pub enum PauliKindForDecomp { + X, + Y, + Z, +} + +/// Decompose an arbitrary multi-qubit physical Pauli string into MPS-frame +/// `(flip_sites, sign_sites, phase)` such that +/// `C† · P · C = phase · X_{flip_sites} · Z_{sign_sites}` +/// where `C` is the Clifford encoded by the tableau. Used for +/// expectation-value computation `⟨Ψ|P|Ψ⟩ = ⟨MPS|C†·P·C|MPS⟩` at any `n`. +/// +/// Algorithm: each single-qubit factor's anticommutation set with the +/// stabilizer generators (`stabs`/`destabs`) determines its contribution +/// to `flip_sites`/`sign_sites`. Multiple factors XOR the contributions. +/// `Y = i·X·Z` adds combined contributions plus an `i` phase factor per +/// `Y` factor (`i^{Y-count}`). +/// +/// Anticommutation lookups: +/// - `X_q` anticom with `S_j` ⇔ `S_j` has `Z` or `Y` at q ⇔ `j ∈ stabs.col_z[q]`. +/// - `Z_q` anticom with `S_j` ⇔ `S_j` has `X` or `Y` at q ⇔ `j ∈ stabs.col_x[q]`. +/// - `Y_q` anticom with `S_j` ⇔ `S_j` has `X`-only or `Z`-only at q ⇔ +/// `j ∈ (stabs.col_x[q] ⊕ stabs.col_z[q])`. +/// # Panics +/// +/// Panics if any qubit index in `pauli` is >= the number of qubits in the +/// tableau. +pub fn decompose_pauli_string( + stabs: &GensGeneric, + destabs: &GensGeneric, + pauli: &[(usize, PauliKindForDecomp)], +) -> (Vec, Vec, Complex64) { + let n = stabs.get_num_qubits(); + // Y-convention single-qubit Pauli multiplication phase table. + // Indexing: Pauli codes I=0, Z=1, X=2, Y=3 (= 2*x_bit + z_bit). + // Entry y_table[a][b] = phase of (Pauli a) · (Pauli b) under the + // convention that Y = iXZ = (1,1) bit pattern is "pure Y" with no + // implicit phase. + let y_table: [[Complex64; 4]; 4] = { + let one = Complex64::new(1.0, 0.0); + let pi = Complex64::new(0.0, 1.0); + let mi = Complex64::new(0.0, -1.0); + [ + [one, one, one, one], // I · {I, Z, X, Y} + [one, one, pi, mi], // Z · {I, Z, X, Y} + [one, mi, one, pi], // X · {I, Z, X, Y} + [one, pi, mi, one], // Y · {I, Z, X, Y} + ] + }; + let pauli_code = |k: PauliKindForDecomp| -> u8 { + match k { + PauliKindForDecomp::Z => 1, + PauliKindForDecomp::X => 2, + PauliKindForDecomp::Y => 3, + } + }; + + // Aggregate per-qubit Pauli factors with Pauli multiplication phase. + // per_q[q] = (current Pauli bits at qubit q, accumulated phase). + let mut per_q: Vec<(u8, Complex64)> = vec![(0, Complex64::new(1.0, 0.0)); n]; + for &(q, kind) in pauli { + assert!(q < n, "decompose_pauli_string: qubit {q} >= num_qubits {n}"); + let new_code = pauli_code(kind); + let cur = per_q[q]; + let phase_factor = y_table[cur.0 as usize][new_code as usize]; + per_q[q] = ((cur.0 ^ new_code), cur.1 * phase_factor); + } + + // Aggregate flip/sign from per-qubit Pauli bits + total user-supplied + // Pauli phase. Each X-bit at q contributes the X anticommutation set; + // each Z-bit at q contributes the Z anticommutation set. A qubit with + // Y bits (1, 1) contributes BOTH (XOR of X- and Z-anticom sets); the + // associated `i` factor of Y = iXZ is captured naturally by the + // y_table in `compute_decomposition_phase`. + let mut flip = S::new(); + let mut sign = S::new(); + let mut total_phase = Complex64::new(1.0, 0.0); + for (q, &(bits, p)) in per_q.iter().enumerate() { + total_phase *= p; + let x_bit = (bits >> 1) & 1; + let z_bit = bits & 1; + if x_bit == 1 { + flip.xor_assign(&stabs.col_z[q]); + sign.xor_assign(&destabs.col_z[q]); + } + if z_bit == 1 { + flip.xor_assign(&stabs.col_x[q]); + sign.xor_assign(&destabs.col_x[q]); + } + } + + let flip_vec: Vec = flip.iter().collect(); + let sign_vec: Vec = sign.iter().collect(); + + let phase_from_compute = compute_decomposition_phase(stabs, destabs, &flip_vec, &sign_vec); + let final_phase = phase_from_compute * total_phase; + (flip_vec, sign_vec, final_phase) +} + +/// Result of decomposing `Z_q` in the stabilizer/destabilizer basis. +#[derive(Debug)] +pub enum ZDecomposition { + /// `Z_q` is in the stabilizer group (no destabilizer component). + /// + /// `Z_q` = phase * prod_{j in `sign_sites`} `S_j` + /// + /// On the MPS, each `S_j` contributes (-1) when the j-th destabilizer + /// index is active. When `sign_sites` is empty, this is a global scalar. + Stabilizer { + /// Overall phase from the decomposition. + phase: Complex64, + /// Stabilizer indices whose product appears in the decomposition. + /// The MPS picks up (-1) for each site j where the destabilizer is active. + sign_sites: Vec, + }, + + /// `Z_q` has a destabilizer component. + /// + /// `Z_q` = phase * (prod_{j in `flip_sites`} `D_j`) * (prod_{k in `sign_sites`} `S_k`) + /// + /// Acting on the MPS: + /// - Each `D_j` flips (X gate) the physical index at MPS site j + /// - Each `S_k` contributes (-1) (Z gate) when the k-th destabilizer is active + /// - The overall complex phase is included + DestabilizerFlip { + /// Destabilizer indices that get flipped (X gates on MPS). + flip_sites: Vec, + /// Overall complex phase from the decomposition. + phase: Complex64, + /// Stabilizer indices whose product appears in the decomposition. + /// The MPS picks up (-1) for each site k where the destabilizer is active. + sign_sites: Vec, + }, +} + +/// Brute-force verify a decomposition by constructing 2^n x 2^n matrices. +/// Only usable for small n (say n<=6). Returns true if correct. +/// +/// # Panics +/// +/// Panics if the number of qubits exceeds what can be represented as a +/// matrix dimension (realistically n > 20). +pub fn verify_decomposition_brute_force( + stabs: &GensGeneric, + destabs: &GensGeneric, + q: usize, + decomp: &ZDecomposition, +) -> bool { + use nalgebra::DMatrix; + + let n = stabs.get_num_qubits(); + let dim = 1usize << n; + let i_mat = DMatrix::::identity(2, 2); + let x_mat = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let z_mat_1q = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(-1.0, 0.0), + ], + ); + let y_mat = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(0.0, -1.0), + Complex64::new(0.0, 1.0), + Complex64::new(0.0, 0.0), + ], + ); + + let gen_matrix = |gens: &GensGeneric, row: usize| -> DMatrix { + let mut result = DMatrix::from_element(1, 1, Complex64::new(1.0, 0.0)); + for qq in 0..n { + let has_x = gens.row_x[row].contains(qq); + let has_z = gens.row_z[row].contains(qq); + let pauli = match (has_x, has_z) { + (false, false) => &i_mat, + (true, false) => &x_mat, + (false, true) => &z_mat_1q, + (true, true) => &y_mat, + }; + result = result.kronecker(pauli); + } + let mut phase = Complex64::new(1.0, 0.0); + if gens.signs_minus.contains(row) { + phase *= Complex64::new(-1.0, 0.0); + } + if gens.signs_i.contains(row) { + phase *= Complex64::new(0.0, 1.0); + } + result * phase + }; + + // Build Z_q matrix + let mut z_mat = DMatrix::from_element(1, 1, Complex64::new(1.0, 0.0)); + for qq in 0..n { + let p = if qq == q { &z_mat_1q } else { &i_mat }; + z_mat = z_mat.kronecker(p); + } + + match decomp { + ZDecomposition::Stabilizer { phase, sign_sites } => { + let mut product = DMatrix::::identity(dim, dim); + for &k in sign_sites { + product = gen_matrix(stabs, k) * product; + } + product *= *phase; + (&z_mat - &product).norm() < 1e-10 + } + ZDecomposition::DestabilizerFlip { + flip_sites, + phase, + sign_sites, + } => { + let mut product = DMatrix::::identity(dim, dim); + for &k in sign_sites { + product = gen_matrix(stabs, k) * product; + } + for &j in flip_sites { + product = gen_matrix(destabs, j) * product; + } + product *= *phase; + let diff = (&z_mat - &product).norm(); + if diff > 1e-10 { + // Find the correct phase by dividing z_mat by the unsigned product + let mut unsigned_product = DMatrix::::identity(dim, dim); + for &k in sign_sites { + unsigned_product = gen_matrix(stabs, k) * unsigned_product; + } + for &j in flip_sites { + unsigned_product = gen_matrix(destabs, j) * unsigned_product; + } + // Z = correct_phase * unsigned_product, so correct_phase = (Z * unsigned_product†)[0,0] + // Since both are unitary Pauli products, the correct phase is Z[0,0] / product[0,0] + // Or more robustly: trace(Z * product†) / dim + let adj = unsigned_product.adjoint(); + let correct = (&z_mat * &adj).trace() + / Complex64::new(f64::from(u32::try_from(dim).unwrap()), 0.0); + eprintln!(" PHASE MISMATCH: diff={diff:.4e}"); + eprintln!(" computed phase={phase}"); + eprintln!(" correct phase={correct:.4}"); + eprintln!(" flip={flip_sites:?}, sign={sign_sites:?}"); + } + diff < 1e-10 + } + } +} + +/// Decompose `Z_q` in the stabilizer/destabilizer basis. +/// +/// This mirrors the measurement logic in `SparseStabY`: `Z_q` is deterministic +/// (in the stabilizer group) when `stabs.col_x[q]` is empty, and requires +/// destabilizer decomposition otherwise. +pub fn decompose_z( + stabs: &GensGeneric, + destabs: &GensGeneric, + q: usize, +) -> ZDecomposition { + if stabs.col_x[q].is_empty() { + // Z_q commutes with all stabilizers -> it's in the stabilizer group. + // Z_q = phase * prod_{j in sign_sites} S_j + // where sign_sites = destabs.col_x[q] (destabilizers that anticommute with Z_q) + let sign = compute_stabilizer_sign(stabs, destabs, q); + let sign_sites: Vec = destabs.col_x[q].iter().collect(); + let phase = if sign < 0.0 { + Complex64::new(-1.0, 0.0) + } else { + Complex64::new(1.0, 0.0) + }; + ZDecomposition::Stabilizer { phase, sign_sites } + } else { + // Z_q anticommutes with at least one stabilizer. + // Find the destabilizer row that anticommutes with Z_q. + decompose_z_nondeterministic(stabs, destabs, q) + } +} + +/// Compute the sign of `Z_q` when it is in the stabilizer group. +/// +/// `Z_q` = (+/-1) * product of stabilizers. The sign is computed by tracking +/// how the destabilizer generators that have X on qubit q combine. +/// +/// This follows the same logic as `SparseStabY::deterministic_meas`. +fn compute_stabilizer_sign( + stabs: &GensGeneric, + destabs: &GensGeneric, + q: usize, +) -> f64 { + // Count minus signs from the destabilizer generators that have X on qubit q. + // These destabs "activate" certain stabilizers to reconstruct Z_q. + let mut num_minuses = destabs.col_x[q].intersection_count(&stabs.signs_minus); + let mut num_is = destabs.col_x[q].intersection_count(&stabs.signs_i); + + // Y-convention correction: add n_Y per participating stab + for row in destabs.col_x[q].iter() { + num_is += stabs.row_x[row].intersection_count(&stabs.row_z[row]); + } + + // W-convention commutation phase accumulation + let mut cumulative_x = S::new(); + for row in destabs.col_x[q].iter() { + num_minuses += stabs.row_z[row].intersection_count(&cumulative_x); + cumulative_x.xor_assign(&stabs.row_x[row]); + } + + // Convert i-count to sign. For the Stabilizer branch the total + // phase must be real (±1), so i-count must be even. + debug_assert!( + num_is.is_multiple_of(2), + "stabilizer sign: i-count {num_is} must be even for real phase" + ); + if num_is % 4 == 2 { + num_minuses += 1; + } + + if num_minuses & 1 != 0 { -1.0 } else { 1.0 } +} + +/// Decompose `Z_q` when it anticommutes with at least one stabilizer. +/// +/// `Z_q` = phase * (product of some stabilizers) * `D_k` +/// +/// We need to find: +/// - k: which destabilizer to flip +/// - phase: the overall complex phase +/// - `sign_sites`: which other stabilizer indices contribute signs +fn decompose_z_nondeterministic( + stabs: &GensGeneric, + destabs: &GensGeneric, + q: usize, +) -> ZDecomposition { + // The destabilizer col_x[q] tells us which destabilizer generators have X on qubit q. + // These are the ones that anticommute with Z_q. + // + // For STN, we need to pick one destabilizer D_k such that Z_q can be written as + // a product of stabilizers times D_k. The standard choice: pick the first + // destabilizer that anticommutes with Z_q (analogous to how measurement picks + // the first anticommuting stabilizer, but here we look at destabilizers). + // + // Actually, the key insight: in the stabilizer formalism, Z_q anticommutes with + // stabilizer generators indexed by stabs.col_x[q]. The destabilizer D_k that + // "pairs" with one of these stabilizers is the one we use. + // + // For the simplest decomposition: take the first anticommuting stabilizer index k. + // Then Z_q = (phase) * (product of stabilizers that anticommute with D_k's effect) * D_k. + // + // The key relationship: destabilizer D_k anticommutes with S_k and commutes with + // all other stabilizers. When we write Z_q in terms of destabilizers and stabilizers, + // the destabilizer component is determined by which stabilizers Z_q anticommutes with. + + // Pick the first stabilizer that anticommutes with Z_q. + // The paired destabilizer at that index is our flip site. + // Now we need to figure out what stabilizer product accompanies the destabilizers. + // Z_q * D_k should commute with all stabilizers (since Z_q anticommutes with S_k + // and D_k anticommutes with S_k, their product commutes with S_k). + // But Z_q might also anticommute with other stabilizers S_j (j != k). + // For those, we need additional destabilizer flips... or stabilizer factors. + // + // Actually, in the STN framework the decomposition is simpler. We express Z_q as: + // Z_q = phase * (prod of some S_j's) * (prod of some D_j's) + // + // The destabilizer part: check destabs.col_x[q] to find all destabilizers that + // have X or Y on qubit q. Wait -- that's the wrong direction. + // + // Let me reconsider. The correct approach follows from the symplectic structure: + // + // The stabilizer/destabilizer tableau T = [D_0, ..., D_{n-1}, S_0, ..., S_{n-1}] + // forms a symplectic basis. Any Pauli P can be uniquely decomposed as: + // P = phase * prod_i D_i^{d_i} * prod_j S_j^{s_j} + // + // where d_i = 1 iff P anticommutes with S_i, + // and s_j = 1 iff P anticommutes with D_j. + // + // For P = Z_q: + // - d_i = 1 iff Z_q anticommutes with S_i, i.e., S_i has X or Y on qubit q + // -> d_i = 1 for i in stabs.col_x[q] + // - s_j = 1 iff Z_q anticommutes with D_j, i.e., D_j has X or Y on qubit q + // -> s_j = 1 for j in destabs.col_x[q] + // + // The phase comes from the ordering and signs of the generators. + + // Collect the destabilizer flip sites (d_i = 1) + let flip_sites: Vec = stabs.col_x[q].iter().collect(); + + // Collect the stabilizer sign sites (s_j = 1) + let sign_sites: Vec = destabs.col_x[q].iter().collect(); + + let phase = compute_decomposition_phase(stabs, destabs, &flip_sites, &sign_sites); + + ZDecomposition::DestabilizerFlip { + flip_sites, + phase, + sign_sites, + } +} + +/// Compute the complex phase of the decomposition `Z_q` = phase * prod(D) * prod(S). +/// +/// Uses the Y-convention per-qubit phase table (matching the stabilizer-TN reference). +/// In Y convention: (x=1, z=1) = Y = iXZ, and Y^2 = I. +fn compute_decomposition_phase( + stabs: &GensGeneric, + destabs: &GensGeneric, + flip_sites: &[usize], + sign_sites: &[usize], +) -> Complex64 { + // Cumulative Pauli string (x, z) parts and complex phase. + let mut cum_x = S::new(); + let mut cum_z = S::new(); + let mut phase = Complex64::new(1.0, 0.0); + + // Helper: multiply cumulative Pauli by a generator, accumulating phase. + let multiply_generator = |cum_x: &mut S, + cum_z: &mut S, + phase: &mut Complex64, + gen_x: &S, + gen_z: &S, + gen_is_minus: bool, + gen_is_i: bool| { + // Generator's own sign + if gen_is_minus { + *phase *= Complex64::new(-1.0, 0.0); + } + if gen_is_i { + *phase *= Complex64::new(0.0, 1.0); + } + + // Per-qubit phase using Y-convention table (matches reference). + // In Y convention: I=0, Z=1, X=2, Y=3 where (1,1) = Y = iXZ. + // Reference: phase_mat = [[1,1,1,1],[1,1,1j,-1j],[1,-1j,1,1j],[1,1j,-1j,1]] + let y_table: [[Complex64; 4]; 4] = { + let one = Complex64::new(1.0, 0.0); + let pi = Complex64::new(0.0, 1.0); + let mi = Complex64::new(0.0, -1.0); + [ + [one, one, one, one], // I * {I,Z,X,Y} + [one, one, pi, mi], // Z * {I,Z,X,Y} + [one, mi, one, pi], // X * {I,Z,X,Y} + [one, pi, mi, one], // Y * {I,Z,X,Y} + ] + }; + + for q in gen_x.iter() { + let p1 = 2 * usize::from(cum_x.contains(q)) + usize::from(cum_z.contains(q)); + let p2 = 2 + usize::from(gen_z.contains(q)); + *phase *= y_table[p1][p2]; + } + for q in gen_z.iter() { + if gen_x.contains(q) { + continue; + } + let p1 = 2 * usize::from(cum_x.contains(q)) + usize::from(cum_z.contains(q)); + *phase *= y_table[p1][1]; + } + + // Update cumulative Pauli + cum_x.xor_assign(gen_x); + cum_z.xor_assign(gen_z); + }; + + // Multiply destabilizers (D_j for j in flip_sites) + for &j in flip_sites { + let is_minus = destabs.signs_minus.contains(j); + let is_i = destabs.signs_i.contains(j); + multiply_generator( + &mut cum_x, + &mut cum_z, + &mut phase, + &destabs.row_x[j], + &destabs.row_z[j], + is_minus, + is_i, + ); + } + + // Multiply stabilizers (S_k for k in sign_sites) + for &k in sign_sites { + let is_minus = stabs.signs_minus.contains(k); + let is_i = stabs.signs_i.contains(k); + multiply_generator( + &mut cum_x, + &mut cum_z, + &mut phase, + &stabs.row_x[k], + &stabs.row_z[k], + is_minus, + is_i, + ); + } + + // (Z_q-specific sanity check removed: this routine is now also used by + // `decompose_pauli_string` for arbitrary Pauli decompositions where the + // cumulative X part can be non-empty.) + + // phase = product_phase (the phase of prod(D)*prod(S) as a Pauli string). + // We need decomp_phase such that Z_q = decomp_phase * prod. + // So decomp_phase = 1 / product_phase. + + if phase.norm_sqr() > 1e-20 { + Complex64::new(1.0, 0.0) / phase + } else { + Complex64::new(1.0, 0.0) + } +} + +#[cfg(test)] +mod tests { + use super::*; + use nalgebra::DMatrix; + use pecos_core::QubitId; + use pecos_simulators::{CliffordGateable, SparseStabY}; + + /// Build the 2^n x 2^n Pauli matrix for generator `row` of `gens`. + /// In Y-convention: (x=1,z=1) = Y (Hermitian). + fn generator_matrix( + gens: &GensGeneric, + row: usize, + n: usize, + ) -> DMatrix { + let i_mat = DMatrix::::identity(2, 2); + let x_mat = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let z_mat = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(-1.0, 0.0), + ], + ); + let y_mat = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(0.0, -1.0), + Complex64::new(0.0, 1.0), + Complex64::new(0.0, 0.0), + ], + ); + + // Build tensor product of per-qubit Paulis + let mut result = DMatrix::from_element(1, 1, Complex64::new(1.0, 0.0)); + for q in 0..n { + let has_x = gens.row_x[row].contains(q); + let has_z = gens.row_z[row].contains(q); + let pauli = match (has_x, has_z) { + (false, false) => &i_mat, + (true, false) => &x_mat, + (false, true) => &z_mat, + (true, true) => &y_mat, // Y convention + }; + result = result.kronecker(pauli); + } + + // Apply phase: (-1)^minus * i^i_bit + let mut phase = Complex64::new(1.0, 0.0); + if gens.signs_minus.contains(row) { + phase *= Complex64::new(-1.0, 0.0); + } + if gens.signs_i.contains(row) { + phase *= Complex64::new(0.0, 1.0); + } + + result * phase + } + + /// Build `Z_q` as a 2^n x 2^n matrix. + fn z_matrix(q: usize, n: usize) -> DMatrix { + let i_mat = DMatrix::::identity(2, 2); + let z_mat = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(-1.0, 0.0), + ], + ); + let mut result = DMatrix::from_element(1, 1, Complex64::new(1.0, 0.0)); + for qq in 0..n { + let pauli = if qq == q { &z_mat } else { &i_mat }; + result = result.kronecker(pauli); + } + result + } + + /// Brute-force verify decomposition phase by matrix multiplication. + fn verify_decomposition_phase(sim: &SparseStabY, q: usize) { + let n = sim.stabs().get_num_qubits(); + let decomp = decompose_z(sim.stabs(), sim.destabs(), q); + + let z_mat = z_matrix(q, n); + + match &decomp { + ZDecomposition::Stabilizer { phase, sign_sites } => { + // Z_q = phase * prod(S_k for k in sign_sites) + let dim = 1usize << n; + let mut product = DMatrix::::identity(dim, dim); + for &k in sign_sites { + product = generator_matrix(sim.stabs(), k, n) * product; + } + product *= *phase; + // Check Z_q == product + let diff = (&z_mat - &product).norm(); + assert!( + diff < 1e-10, + "Stabilizer decomp for Z_{q}: ||Z - phase*prod(S)|| = {diff:.4e}, phase={phase}" + ); + } + ZDecomposition::DestabilizerFlip { + flip_sites, + phase, + sign_sites, + } => { + // Z_q = phase * prod(D_j) * prod(S_k) + let dim = 1usize << n; + let mut product = DMatrix::::identity(dim, dim); + // Multiply stabilizers first (rightmost) + for &k in sign_sites { + product = generator_matrix(sim.stabs(), k, n) * product; + } + // Then destabilizers + for &j in flip_sites { + product = generator_matrix(sim.destabs(), j, n) * product; + } + product *= *phase; + let diff = (&z_mat - &product).norm(); + assert!( + diff < 1e-10, + "DestabFlip decomp for Z_{q}: ||Z - phase*prod(D)*prod(S)|| = {diff:.4e}\n \ + phase={phase}, flip={flip_sites:?}, sign={sign_sites:?}" + ); + } + } + } + + // Phase verification is done via the verification test (uses StabMps which has destab sign fixups). + + #[test] + fn test_destab_sign_tracking_z() { + // Initial state: D_0 = X_0. Z(0) conjugates X_0 → -X_0. + // With destab sign tracking, the minus should appear in signs_minus. + let mut sim = SparseStabY::new(2).with_destab_sign_tracking(); + + // Initial: D_0 = X_0 (no minus) + assert!(sim.destabs().row_x[0].contains(0)); + assert!(!sim.destabs().signs_minus.contains(0)); + + // Z(0) should conjugate: Z*X*Z = -X + sim.z(&[QubitId(0)]); + + assert!( + sim.destabs().row_x[0].contains(0), + "D[0] should still have X on q0" + ); + assert!( + sim.destabs().signs_minus.contains(0), + "D[0] should have minus=true after Z (Z*X*Z = -X)" + ); + } + + #[test] + fn test_decomposition_phase_brute_force_seed102_circuit() { + // Reproduce the seed 102 Clifford prefix before the failing T gate. + // Gate sequence from fuzz(2,10,102): + // rz(q1), sz(q1), sz(q0), h(q0), sz(q0), x(q1), cx(1,0), x(q1), t(q0), x(q0) + // The first rz is on initial state (scalar), so the first DestabilizerFlip + // is at t(q0) = step 9. + let q0 = QubitId(0); + let q1 = QubitId(1); + let mut sim = SparseStabY::new(2); + + // Step 1: rz(q1) — on initial state, this is a scalar. Skip for tableau. + // Step 2: sz(q1) + sim.sz(&[q1]); + // Step 3: sz(q0) + sim.sz(&[q0]); + // Step 4: h(q0) + sim.h(&[q0]); + // Step 5: sz(q0) + sim.sz(&[q0]); + // Step 6: x(q1) + sim.x(&[q1]); + // Step 7: cx(1, 0) + sim.cx(&[(q1, q0)]); + // Step 8: x(q1) + sim.x(&[q1]); + + // Now verify the decomposition of Z_0 (the T gate target) + eprintln!("=== Seed 102 state before T(q0) ==="); + let n = 2; + for i in 0..n { + let stab_x: Vec = sim.stabs().row_x[i].iter().collect(); + let stab_z: Vec = sim.stabs().row_z[i].iter().collect(); + let destab_x: Vec = sim.destabs().row_x[i].iter().collect(); + let destab_z: Vec = sim.destabs().row_z[i].iter().collect(); + let s_minus = sim.stabs().signs_minus.contains(i); + let s_i = sim.stabs().signs_i.contains(i); + let d_minus = sim.destabs().signs_minus.contains(i); + let d_i = sim.destabs().signs_i.contains(i); + eprintln!(" stab[{i}]: x={stab_x:?} z={stab_z:?} minus={s_minus} i={s_i}"); + eprintln!(" destab[{i}]: x={destab_x:?} z={destab_z:?} minus={d_minus} i={d_i}"); + } + + let decomp = decompose_z(sim.stabs(), sim.destabs(), 0); + eprintln!(" decomposition: {decomp:?}"); + + verify_decomposition_phase(&sim, 0); + verify_decomposition_phase(&sim, 1); + } + + #[test] + fn test_z_on_initial_state_is_stabilizer() { + // Initial state |00>: stabilizers are Z_0, Z_1, destabilizers X_0, X_1 + // Z_0 is in the stabilizer group with phase +1 + // sign_sites = destabs.col_x[0] = {0} (X_0 has X on q0) + let sim = SparseStabY::new(2); + let decomp = decompose_z(sim.stabs(), sim.destabs(), 0); + match decomp { + ZDecomposition::Stabilizer { phase, .. } => { + assert!( + (phase.re - 1.0).abs() < f64::EPSILON, + "Z_0 should have phase +1 on |0>" + ); + } + ZDecomposition::DestabilizerFlip { .. } => panic!("Z_0 should be a stabilizer on |00>"), + } + } + + #[test] + fn test_z_on_x_state_is_stabilizer_minus() { + // State |10>: X on qubit 0. Z_0 eigenvalue is -1. + let mut sim = SparseStabY::new(2); + sim.x(&[QubitId(0)]); + let decomp = decompose_z(sim.stabs(), sim.destabs(), 0); + match decomp { + ZDecomposition::Stabilizer { phase, .. } => { + assert!( + (phase.re + 1.0).abs() < f64::EPSILON, + "Z_0 should have phase -1 on |1>" + ); + } + ZDecomposition::DestabilizerFlip { .. } => panic!("Z_0 should be a stabilizer on |10>"), + } + } + + #[test] + fn test_z_after_hadamard_is_destabilizer() { + // State |+> = H|0>: stabilizer is X, destabilizer is Z + let mut sim = SparseStabY::new(1); + sim.h(&[QubitId(0)]); + let decomp = decompose_z(sim.stabs(), sim.destabs(), 0); + match decomp { + ZDecomposition::DestabilizerFlip { + flip_sites, + sign_sites, + .. + } => { + assert_eq!(flip_sites, vec![0], "should flip destabilizer 0"); + assert!(sign_sites.is_empty(), "no sign sites for simple case"); + } + ZDecomposition::Stabilizer { .. } => panic!("Z should be a destabilizer flip after H"), + } + } + + /// Diagnostic: print (phase, `flip_sites`, `sign_sites`, Ys) for a variety + /// of states. Used to understand what cases `decompose_z` actually produces. + #[test] + fn test_decomposition_cases_survey() { + // Helper: apply gates, decompose Z_q, report (phase, Ys, flip, sign) + let survey_q = |label: &str, q: usize, gates: fn(&mut SparseStabY)| { + let mut sim = SparseStabY::new(3); + gates(&mut sim); + let decomp = decompose_z(sim.stabs(), sim.destabs(), q); + match decomp { + ZDecomposition::Stabilizer { + phase, + ref sign_sites, + } => { + eprintln!( + "{label} Z_{q}: Stabilizer phase={phase:.3} sign_sites={sign_sites:?}" + ); + } + ZDecomposition::DestabilizerFlip { + ref flip_sites, + phase, + ref sign_sites, + } => { + let ys = flip_sites.iter().filter(|f| sign_sites.contains(f)).count(); + eprintln!( + "{label} Z_{q}: DestabFlip phase={phase:.3} flip={flip_sites:?} sign={sign_sites:?} Ys={ys}" + ); + } + } + }; + let survey = |label: &str, gates: fn(&mut SparseStabY)| { + let mut sim = SparseStabY::new(3); + gates(&mut sim); + let decomp = decompose_z(sim.stabs(), sim.destabs(), 0); + match decomp { + ZDecomposition::Stabilizer { + phase, + ref sign_sites, + } => { + eprintln!("{label}: Stabilizer phase={phase:.3} sign_sites={sign_sites:?}"); + } + ZDecomposition::DestabilizerFlip { + ref flip_sites, + phase, + ref sign_sites, + } => { + let ys = flip_sites.iter().filter(|f| sign_sites.contains(f)).count(); + eprintln!( + "{label}: DestabFlip phase={phase:.3} flip={flip_sites:?} sign={sign_sites:?} Ys={ys}" + ); + } + } + }; + + survey("|0⟩", |s| { + let _ = s; + }); + survey("H|0⟩", |s| { + s.h(&[QubitId(0)]); + }); + survey("X|0⟩=|1⟩", |s| { + s.x(&[QubitId(0)]); + }); + survey("SH|0⟩", |s| { + s.h(&[QubitId(0)]); + s.sz(&[QubitId(0)]); + }); + // Multi-site cases via various tableau setups + // CX then decompose Z_0 or Z_1 -- decomp depends on which qubit + survey_q("H,CX(0,1)", 0, |s| { + s.h(&[QubitId(0)]); + s.cx(&[(QubitId(0), QubitId(1))]); + }); + survey_q("H,CX(0,1)", 1, |s| { + s.h(&[QubitId(0)]); + s.cx(&[(QubitId(0), QubitId(1))]); + }); + survey_q("H,H,CX(0,1)", 0, |s| { + s.h(&[QubitId(0)]); + s.h(&[QubitId(1)]); + s.cx(&[(QubitId(0), QubitId(1))]); + }); + survey_q("H,H,CX(0,1)", 1, |s| { + s.h(&[QubitId(0)]); + s.h(&[QubitId(1)]); + s.cx(&[(QubitId(0), QubitId(1))]); + }); + // Looking for multi-site: stab has X on multiple qubits after some sequence + survey_q("H(0),CX(0,1),H(0)", 0, |s| { + s.h(&[QubitId(0)]); + s.cx(&[(QubitId(0), QubitId(1))]); + s.h(&[QubitId(0)]); + }); + survey_q("H(0),CX(0,1),H(0),CX(0,1)", 0, |s| { + s.h(&[QubitId(0)]); + s.cx(&[(QubitId(0), QubitId(1))]); + s.h(&[QubitId(0)]); + s.cx(&[(QubitId(0), QubitId(1))]); + }); + // After H,CX,H on q0: X_0 X_1 stab, should give decompose with multiple flips + survey_q("H(0),CX(0,1),H(1)", 0, |s| { + s.h(&[QubitId(0)]); + s.cx(&[(QubitId(0), QubitId(1))]); + s.h(&[QubitId(1)]); + }); + // GHZ-like state + survey_q("H,CX(0,1),CX(1,2)", 0, |s| { + s.h(&[QubitId(0)]); + s.cx(&[(QubitId(0), QubitId(1))]); + s.cx(&[(QubitId(1), QubitId(2))]); + }); + survey_q("H,CX(0,1),CX(1,2)", 2, |s| { + s.h(&[QubitId(0)]); + s.cx(&[(QubitId(0), QubitId(1))]); + s.cx(&[(QubitId(1), QubitId(2))]); + }); + // Setup with Y-type stabilizers: SH gives Y-basis + survey_q("SH,CX(0,1)", 0, |s| { + s.h(&[QubitId(0)]); + s.sz(&[QubitId(0)]); + s.cx(&[(QubitId(0), QubitId(1))]); + }); + survey_q("SH,CX(0,1)", 1, |s| { + s.h(&[QubitId(0)]); + s.sz(&[QubitId(0)]); + s.cx(&[(QubitId(0), QubitId(1))]); + }); + // Try to get Ys > 0: need same generator index in both flip_sites and sign_sites + // Requires stab_k and destab_k both have X on same qubit q + survey_q("S(0),H(0)", 0, |s| { + s.sz(&[QubitId(0)]); + s.h(&[QubitId(0)]); + }); + // H,S(0) gives stab=Y_0, destab=X_0. col_x[0] for both = {0}. Ys=1! + // For Z_0 decomp, flip = stabs.col_x[0] = {0}, sign = destabs.col_x[0] = {0}, Ys=1 + survey_q("H(0),S(0)", 0, |s| { + s.h(&[QubitId(0)]); + s.sz(&[QubitId(0)]); + }); + // More Y cases + survey_q("H(0),S(0),CX(0,1)", 0, |s| { + s.h(&[QubitId(0)]); + s.sz(&[QubitId(0)]); + s.cx(&[(QubitId(0), QubitId(1))]); + }); + survey_q("H(0),S(0),CX(0,1)", 1, |s| { + s.h(&[QubitId(0)]); + s.sz(&[QubitId(0)]); + s.cx(&[(QubitId(0), QubitId(1))]); + }); + survey_q("H(1),S(1),CX(0,1)", 0, |s| { + s.h(&[QubitId(1)]); + s.sz(&[QubitId(1)]); + s.cx(&[(QubitId(0), QubitId(1))]); + }); + survey_q("H,H,S(0),S(1),CX(0,1)", 0, |s| { + s.h(&[QubitId(0)]); + s.h(&[QubitId(1)]); + s.sz(&[QubitId(0)]); + s.sz(&[QubitId(1)]); + s.cx(&[(QubitId(0), QubitId(1))]); + }); + survey_q("H,H,S(0),S(1),CX(0,1)", 1, |s| { + s.h(&[QubitId(0)]); + s.h(&[QubitId(1)]); + s.sz(&[QubitId(0)]); + s.sz(&[QubitId(1)]); + s.cx(&[(QubitId(0), QubitId(1))]); + }); + } + + #[test] + fn test_z_after_bell_state() { + // Bell state: H on q0, then CX(q0, q1) + // Stabilizers: X_0 X_1, Z_0 Z_1 + // Z_0 anticommutes with X_0 X_1 (has X on q0) + let mut sim = SparseStabY::new(2); + sim.h(&[QubitId(0)]); + sim.cx(&[(QubitId(0), QubitId(1))]); + let decomp = decompose_z(sim.stabs(), sim.destabs(), 0); + match decomp { + ZDecomposition::DestabilizerFlip { flip_sites, .. } => { + // Should have exactly one flip site + assert_eq!(flip_sites.len(), 1, "should have one flip site"); + } + ZDecomposition::Stabilizer { .. } => { + panic!("Z_0 should be a destabilizer flip in Bell state") + } + } + } +} diff --git a/exp/pecos-stab-tn/src/stab_mps/renyi.rs b/exp/pecos-stab-tn/src/stab_mps/renyi.rs new file mode 100644 index 000000000..9f3f33782 --- /dev/null +++ b/exp/pecos-stab-tn/src/stab_mps/renyi.rs @@ -0,0 +1,1023 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! CAMPS-native second Rényi entropy `S_2`. +//! +//! Implements Pauli Coefficient Enumeration (PCE) from Liu-Clark 2412.17209 +//! Section VI.C. For a CAMPS state ρ = C |φ⟩⟨φ| C† where |φ⟩ is a product MPS: +//! +//! 1. For each MPS site j, find non-vanishing single-qubit Paulis (up to 3 per site) +//! and their coefficients (Bloch-vector components). +//! 2. Map each `G̃_k` to `G_k` = C · `G̃_k` · C† (a Pauli string on all N qubits). +//! 3. Gaussian-eliminate the region-B part of `G_k` to find generators {`Q_j`} supported +//! only on region A. +//! 4. Enumerate all 2^M combinations of `Q_j`'s, compute coefficients, and sum +//! squared coefficients to get `Tr(ρ_A²)`. +//! +//! PCE complexity: O(M · 2^M) enumeration. For magic-doped Clifford circuits with +//! few T gates, M is small relative to N, making PCE practical for many qubits. +//! +//! A PCMPS variant (next step) represents the coefficient state as an MPS to +//! reach 100+ qubits; deferred. + +use crate::mps::Mps; +use pecos_simulators::SparseStabY; + +/// A Pauli string on N qubits: (x, z) bitvectors and a real coefficient. +/// +/// The coefficient is real because every Pauli string produced here is +/// Hermitian (r·σ with real r, conjugated by a Clifford stays Hermitian). +#[derive(Clone, Debug)] +pub(crate) struct PauliString { + pub x: Vec, + pub z: Vec, + pub coef: f64, +} + +impl PauliString { + pub fn identity(n: usize) -> Self { + Self { + x: vec![false; n], + z: vec![false; n], + coef: 1.0, + } + } + + /// Returns true if this Pauli is supported only on qubits in `region_a`. + pub fn supported_on(&self, region_a: &[bool]) -> bool { + for (q, in_a) in region_a.iter().enumerate() { + if !in_a && (self.x[q] || self.z[q]) { + return false; + } + } + true + } +} + +/// Compute Bloch vector (`r_x`, `r_y`, `r_z`) for each MPS site, assuming bond dim 1. +/// +/// `r_x` = Tr(X `ρ_j`) = 2 `Re(ψ_0`* `ψ_1`) (for normalized state |`ψ_j`⟩ = `ψ_0|0`⟩ + `ψ_1|1`⟩) +/// `r_y` = Tr(Y `ρ_j`) = -2 `Im(ψ_0`* `ψ_1`) +/// `r_z` = Tr(Z `ρ_j`) = |`ψ_0|²` - |`ψ_1|²` +pub(crate) fn bloch_vectors(mps: &Mps) -> Result, String> { + if mps.max_bond_dim() != 1 { + return Err(format!( + "bloch_vectors requires bond dim 1, got {}", + mps.max_bond_dim() + )); + } + let n = mps.num_sites(); + let mut out = Vec::with_capacity(n); + for j in 0..n { + let t = &mps.tensors()[j]; + // Tensor shape: (chi_l=1, 2*chi_r=2). Extract psi_0 = t[0, 0], psi_1 = t[0, 1]. + let psi0 = t[(0, 0)]; + let psi1 = t[(0, 1)]; + let rx = 2.0 * (psi0.conj() * psi1).re; + let ry = -2.0 * (psi0.conj() * psi1).im; + let rz = psi0.norm_sqr() - psi1.norm_sqr(); + out.push((rx, ry, rz)); + } + Ok(out) +} + +/// Map a single-qubit Pauli at site j through the tableau's Clifford C. +/// Returns G = C · `P_j` · C† as a `PauliString` on N qubits. +/// +/// Uses: `destab_j` = C `X_j` C†, `stab_j` = C `Z_j` C†. Then C `Y_j` C† = i · `destab_j` · `stab_j` +/// = (`destab_j` · `stab_j` with sign/phase adjustments). +pub(crate) fn map_pauli_through_tableau( + tableau: &SparseStabY, + site: usize, + pauli: char, + coef: f64, +) -> PauliString { + let n = tableau.num_qubits(); + match pauli { + 'X' => { + let mut x = vec![false; n]; + let mut z = vec![false; n]; + for q in &tableau.destabs().row_x[site] { + x[q] = true; + } + for q in &tableau.destabs().row_z[site] { + z[q] = true; + } + let mut c = coef; + if tableau.destabs().signs_minus.contains(site) { + c = -c; + } + // signs_i contributes i^count. For Hermitian generators the + // total phase (including Y-count) must be real. Count Y-bits + // (x AND z set) to get the Y-count, combine with signs_i. + if tableau.destabs().signs_i.contains(site) { + let y_count: usize = x + .iter() + .zip(z.iter()) + .filter(|(xi, zi)| **xi && **zi) + .count(); + // Total i-count: 1 (from signs_i) + y_count. Must be even + // for a real coefficient. + let total_i = 1 + y_count; + debug_assert!( + total_i.is_multiple_of(2), + "destab signs_i + Y-count must be even for real coefficient, got {total_i}" + ); + if total_i % 4 == 2 { + c = -c; + } + } + PauliString { x, z, coef: c } + } + 'Z' => { + let mut x = vec![false; n]; + let mut z = vec![false; n]; + for q in &tableau.stabs().row_x[site] { + x[q] = true; + } + for q in &tableau.stabs().row_z[site] { + z[q] = true; + } + let mut c = coef; + if tableau.stabs().signs_minus.contains(site) { + c = -c; + } + if tableau.stabs().signs_i.contains(site) { + let y_count: usize = x + .iter() + .zip(z.iter()) + .filter(|(xi, zi)| **xi && **zi) + .count(); + let total_i = 1 + y_count; + debug_assert!( + total_i.is_multiple_of(2), + "stab signs_i + Y-count must be even for real coefficient, got {total_i}" + ); + if total_i % 4 == 2 { + c = -c; + } + } + PauliString { x, z, coef: c } + } + 'Y' => { + // Y_j = i · X_j · Z_j ⇒ C Y_j C† = i · D · S + // where D = C X_j C† and S = C Z_j C†. + // D and S anticommute (X_j, Z_j anticommute; conjugation preserves it), + // so the accumulated per-qubit i-count is odd, making i · D·S a real + // Hermitian Pauli with ±1 sign. + let dx = map_pauli_through_tableau(tableau, site, 'X', 1.0); + let dz = map_pauli_through_tableau(tableau, site, 'Z', 1.0); + let mut x = vec![false; n]; + let mut z = vec![false; n]; + let mut minus_count: u32 = 0; + let mut i_count: u32 = 0; + for q in 0..n { + x[q] = dx.x[q] ^ dz.x[q]; + z[q] = dx.z[q] ^ dz.z[q]; + let pa = pauli_idx(dx.x[q], dx.z[q]); + let pb = pauli_idx(dz.x[q], dz.z[q]); + let (m, i_b) = pauli_phase(pa, pb); + minus_count += u32::from(m); + i_count += u32::from(i_b); + } + // Total phase of i · D·S = i^{1 + i_count} · (-1)^{minus_count}. + // Must be real (i_count odd). Result sign: + // i^{1+k} for k odd, k=2j+1 → i^{2j+2} = (-1)^{j+1} + debug_assert_eq!(i_count % 2, 1, "C Y C† must be Hermitian"); + let j = (i_count - 1) / 2; + let mut c = coef * dx.coef * dz.coef; + if (j + 1) % 2 == 1 { + c = -c; + } + if minus_count % 2 == 1 { + c = -c; + } + PauliString { x, z, coef: c } + } + 'I' => PauliString::identity(n), + _ => panic!("invalid pauli: {pauli}"), + } +} + +/// Y-convention Pauli index (I=0, Z=1, X=2, Y=3) from (x, z) bits. +fn pauli_idx(x: bool, z: bool) -> u8 { + match (x, z) { + (false, false) => 0, + (false, true) => 1, + (true, false) => 2, + (true, true) => 3, + } +} + +/// Phase (`minus_bit`, `i_bit`) of `Pauli_a` · `Pauli_b` with I=0,Z=1,X=2,Y=3. +/// Encoding: +1=(0,0), -1=(1,0), +i=(0,1), -i=(1,1). +fn pauli_phase(a: u8, b: u8) -> (u8, u8) { + match (a, b) { + (1, 2) | (3, 1) | (2, 3) => (0, 1), // +i: Z·X, Y·Z, X·Y + (2, 1) | (1, 3) | (3, 2) => (1, 1), // -i: X·Z, Z·Y, Y·X + _ => (0, 0), // I or same Pauli + } +} + +/// (Deprecated / unused) Gauss-eliminate Pauli strings to find subset +/// supported only on region A. Kept for reference; PCE now enumerates +/// per-site choices directly since generators from same site anti-commute. +#[allow(dead_code)] +pub(crate) fn restrict_to_region_a( + generators: Vec, + region_a_mask: &[bool], + num_qubits: usize, +) -> Vec { + let region_b_mask: Vec = region_a_mask.iter().map(|b| !b).collect(); + // Build matrix: each row is 2N-bit (x then z), coefficient tracked separately. + // Eliminate rows by pivoting on region_b bits first. + let mut rows: Vec = generators; + // Bits of region B: for each qubit q in B, the x bit (position q) and z bit + // (position num_qubits + q). We want to zero these out. + let mut b_bit_positions: Vec<(usize, bool)> = Vec::new(); // (qubit, is_x) + for (q, &is_b) in region_b_mask.iter().enumerate() { + if is_b { + b_bit_positions.push((q, true)); // x-bit + b_bit_positions.push((q, false)); // z-bit + } + } + + let row_bit = |row: &PauliString, q: usize, is_x: bool| -> bool { + if is_x { row.x[q] } else { row.z[q] } + }; + + let mut current = 0; + for &(q, is_x) in &b_bit_positions { + if current >= rows.len() { + break; + } + // Find row with 1 in this bit. + let found = rows[current..] + .iter() + .position(|row| row_bit(row, q, is_x)) + .map(|offset| current + offset); + if let Some(piv) = found { + rows.swap(current, piv); + for r in 0..rows.len() { + if r != current && row_bit(&rows[r], q, is_x) { + // Combine rows as Pauli product: P_r · P_current. + // Bits XOR; coefficient picks up per-qubit phase. + // For commuting-generator case, total phase is real (±1); + // i-count must be even. + let mut minus_count: u32 = 0; + let mut i_count: u32 = 0; + for qq in 0..num_qubits { + let pa = pauli_idx(rows[r].x[qq], rows[r].z[qq]); + let pb = pauli_idx(rows[current].x[qq], rows[current].z[qq]); + let (m, i_b) = pauli_phase(pa, pb); + minus_count += u32::from(m); + i_count += u32::from(i_b); + rows[r].x[qq] ^= rows[current].x[qq]; + rows[r].z[qq] ^= rows[current].z[qq]; + } + // PCE assumes generators mutually commute → i_count even. + // Non-commuting generators (e.g. same-site X and Y) violate + // this; we approximate with |phase|. + let j = i_count / 2; + let mut combined = rows[r].coef * rows[current].coef; + if j % 2 == 1 { + combined = -combined; + } + if minus_count % 2 == 1 { + combined = -combined; + } + rows[r].coef = combined; + } + } + current += 1; + } + } + + // Return rows with zero support on B. + rows.into_iter() + .filter(|r| r.supported_on(region_a_mask)) + .collect() +} + +/// Compute `S_2` entropy via Pauli Coefficient Enumeration (PCE). +/// +/// Formula: `Tr(ρ_A²)` = (`1/2^{N_A`}) · Σ_{P̃ : supp(C P̃ C†) ⊆ A} ∏_j `c_j(P̃_j)²` +/// where `c_j(P̃_j)` = `Tr(ρ_j` · `P̃_j`) ∈ {1, `r_x`, `r_y`, `r_z`}. +/// +/// We enumerate site-independent choices (I or one of the non-zero Paulis at +/// each site), map the product through the tableau, and keep terms supported +/// on A. Combinations count is ∏_j (1 + `count_j`). For Clifford+T circuits, +/// most sites have `count_j` ∈ {0,1}; full-magic sites have `count_j` = 3 giving +/// up to 4^N. Errors out above 2^22 combos. +/// +/// # Errors +/// +/// Returns an error string if the mask length doesn't match the MPS, or if +/// the number of Pauli combinations exceeds the safety limit. +/// +/// # Panics +/// +/// Panics if the region-A size exceeds u16 range (would require > 65535 qubits). +pub fn compute_s2_pce( + mps: &Mps, + tableau: &SparseStabY, + region_a_mask: &[bool], +) -> Result { + let n = mps.num_sites(); + if region_a_mask.len() != n { + return Err("region_a_mask length mismatch".into()); + } + + let bvs = bloch_vectors(mps)?; + let tol = 1e-12; + + // For each site, list the available (coef, mapped_PauliString) choices. + // The identity choice has coef=1 and a zero PauliString on all qubits. + // Non-identity choices include non-zero X/Y/Z Bloch components. + let mut site_choices: Vec> = Vec::with_capacity(n); + let mut total_combos: u128 = 1; + for (j, &(rx, ry, rz)) in bvs.iter().enumerate() { + let mut opts: Vec<(f64, PauliString)> = Vec::with_capacity(4); + opts.push((1.0, PauliString::identity(n))); + if rx.abs() > tol { + opts.push((rx, map_pauli_through_tableau(tableau, j, 'X', 1.0))); + } + if ry.abs() > tol { + opts.push((ry, map_pauli_through_tableau(tableau, j, 'Y', 1.0))); + } + if rz.abs() > tol { + opts.push((rz, map_pauli_through_tableau(tableau, j, 'Z', 1.0))); + } + total_combos = total_combos.saturating_mul(opts.len() as u128); + site_choices.push(opts); + } + if total_combos > (1u128 << 22) { + return Err(format!("PCE would enumerate {total_combos} > limit 2^22")); + } + + // Enumerate all combinations as mixed-radix index across sites. + let n_a: usize = region_a_mask.iter().filter(|&&b| b).count(); + let mut tr_sq: f64 = 0.0; + let mut idx = vec![0usize; n]; + loop { + // Combine: product of per-site Bloch coefficients × XOR of mapped Paulis + // (cross-site Paulis commute so total sign is product of each mapped coef's sign). + let mut combined_x = vec![false; n]; + let mut combined_z = vec![false; n]; + let mut coef = 1.0; + for (j, opts) in site_choices.iter().enumerate() { + let (bloch, ps) = &opts[idx[j]]; + coef *= bloch; + // Accumulate Pauli product (cross-site, so just XOR; per-qubit phase + // is trivial because different-site Paulis share no qubit support in + // P̃, but the *mapped* ps spans all qubits, so we still track phase). + let mut minus_count: u32 = 0; + let mut i_count: u32 = 0; + for q in 0..n { + let pa = pauli_idx(combined_x[q], combined_z[q]); + let pb = pauli_idx(ps.x[q], ps.z[q]); + let (m, i_b) = pauli_phase(pa, pb); + minus_count += u32::from(m); + i_count += u32::from(i_b); + combined_x[q] ^= ps.x[q]; + combined_z[q] ^= ps.z[q]; + } + // All mapped P_j from different sites commute → i_count even. + debug_assert_eq!(i_count % 2, 0, "cross-site mapped Paulis must commute"); + let j_half = i_count / 2; + coef *= ps.coef; + if (j_half + minus_count) % 2 == 1 { + coef = -coef; + } + } + + // Check support on region A. + let mut on_a = true; + for q in 0..n { + if !region_a_mask[q] && (combined_x[q] || combined_z[q]) { + on_a = false; + break; + } + } + if on_a { + tr_sq += coef * coef; + } + + // Advance mixed-radix counter. + let mut carry = true; + for j in 0..n { + if !carry { + break; + } + idx[j] += 1; + if idx[j] >= site_choices[j].len() { + idx[j] = 0; + } else { + carry = false; + } + } + if carry { + break; + } + } + // n_a is bounded by the number of qubits (enforced by early checks) so n_a <= 22. + tr_sq *= 0.5_f64.powi(i32::from(u16::try_from(n_a).expect("n_a fits in u16"))); + + if tr_sq < 1e-30 { + Ok(f64::INFINITY) + } else { + Ok(-tr_sq.ln()) + } +} + +/// `S_2` via full `F_2` enumeration of the 2N-bit Pauli null-space with +/// site-separable squared-weights. Handles arbitrary (multi-axis) Bloch. +/// +/// Formula: `Tr(ρ_A²)` = (`1/2^{N_A`}) · Σ_{P̃ : supp(C P̃ C†) ⊆ A} ∏_j `w_j(P̃_j)` +/// where weights are squared Bloch components in Y-convention: +/// `w_j(x̃=0,z̃=0)` = 1 (I) +/// `w_j(x̃=1,z̃=0)` = `r_x²` (X) +/// `w_j(x̃=0,z̃=1)` = `r_z²` (Z) +/// `w_j(x̃=1,z̃=1)` = `r_y²` (XZ ≈ -iY in standard Pauli) +/// +/// Constraints: 2(N-N_A) linear parity checks over `F_2^{2N`} encoding that +/// (C P̃ C†) has no support on region B. Gauss-eliminate to find null +/// space of dim `d`; enumerate 2^d terms. Errors out above 2^22. +/// +/// Covers the single-axis case as a special case (inactive axes add +/// unit-weight constraints that reduce effective null dim). +/// +/// # Errors +/// +/// Returns an error string if the mask length doesn't match the MPS, or if +/// the null-space dimension exceeds the enumeration limit. +/// +/// # Panics +/// +/// Panics if the region-A size exceeds u16 range (would require > 65535 qubits). +pub fn compute_s2_pcmps_tn( + mps: &Mps, + tableau: &SparseStabY, + region_a_mask: &[bool], +) -> Result { + let n = mps.num_sites(); + if region_a_mask.len() != n { + return Err("region_a_mask length mismatch".into()); + } + let bvs = bloch_vectors(mps)?; + let tol = 1e-12; + + // Variables: for site j, x̃_j = bit 2j, z̃_j = bit 2j+1. Total 2N bits. + let n_bits = 2 * n; + + // Per-site weights indexed by (x̃, z̃) ∈ {0,1}² ordered 00, 10, 01, 11. + // Also record which patterns are forced zero (constraints to add). + let mut weights: Vec<[f64; 4]> = Vec::with_capacity(n); + let mut zero_bit_constraints: Vec> = Vec::new(); + for (j, &(rx, ry, rz)) in bvs.iter().enumerate() { + let rx2 = rx * rx; + let ry2 = ry * ry; + let rz2 = rz * rz; + weights.push([1.0, rx2, rz2, ry2]); + // Zero-weight patterns ⇒ force bit combinations to 0. + // If rx = 0 AND ry = 0: force x̃_j = 0 (eliminates X and Y options). + if rx2 < tol && ry2 < tol { + let mut row = vec![false; n_bits]; + row[2 * j] = true; + zero_bit_constraints.push(row); + } + // If rz = 0 AND ry = 0: force z̃_j = 0. + if rz2 < tol && ry2 < tol { + let mut row = vec![false; n_bits]; + row[2 * j + 1] = true; + zero_bit_constraints.push(row); + } + // If rx = 0 AND rz = 0 (only Y): force x̃_j = z̃_j. + if rx2 < tol && rz2 < tol && ry2 > tol { + let mut row = vec![false; n_bits]; + row[2 * j] = true; + row[2 * j + 1] = true; + zero_bit_constraints.push(row); + } + } + + // Support-on-A constraints: for each B-site q, 2 linear constraints (x and z bits of CP̃C†). + // (CP̃C†)_q x-bit = ⊕_j (x̃_j · destab[j].row_x[q] ⊕ z̃_j · stab[j].row_x[q]) + // (CP̃C†)_q z-bit = ⊕_j (x̃_j · destab[j].row_z[q] ⊕ z̃_j · stab[j].row_z[q]) + let destabs = tableau.destabs(); + let stabs = tableau.stabs(); + let mut support_constraints: Vec> = Vec::new(); + for (q, &is_a) in region_a_mask.iter().enumerate() { + if is_a { + continue; + } + let mut row_x = vec![false; n_bits]; + let mut row_z = vec![false; n_bits]; + for j in 0..n { + if destabs.row_x[j].contains(q) { + row_x[2 * j] ^= true; + } + if stabs.row_x[j].contains(q) { + row_x[2 * j + 1] ^= true; + } + if destabs.row_z[j].contains(q) { + row_z[2 * j] ^= true; + } + if stabs.row_z[j].contains(q) { + row_z[2 * j + 1] ^= true; + } + } + if row_x.iter().any(|&b| b) { + support_constraints.push(row_x); + } + if row_z.iter().any(|&b| b) { + support_constraints.push(row_z); + } + } + + // Combine all constraints. + let mut a_rows: Vec> = Vec::new(); + a_rows.extend(zero_bit_constraints); + a_rows.extend(support_constraints); + let n_rows = a_rows.len(); + + // RREF over F_2. + let mut pivot_col_of_row: Vec> = vec![None; n_rows]; + let mut col_is_pivot: Vec = vec![false; n_bits]; + let mut r = 0; + for c in 0..n_bits { + if r >= n_rows { + break; + } + let found = a_rows[r..] + .iter() + .position(|row| row[c]) + .map(|offset| r + offset); + if let Some(rr) = found { + a_rows.swap(r, rr); + let pivot_row = a_rows[r].clone(); + for (rr, row) in a_rows.iter_mut().enumerate() { + if rr != r && row[c] { + for (cell, &piv) in row.iter_mut().zip(pivot_row.iter()) { + *cell ^= piv; + } + } + } + pivot_col_of_row[r] = Some(c); + col_is_pivot[c] = true; + r += 1; + } + } + let rank = r; + let free_cols: Vec = (0..n_bits).filter(|&c| !col_is_pivot[c]).collect(); + let null_dim = free_cols.len(); + + let n_a: usize = region_a_mask.iter().filter(|&&b| b).count(); + + if null_dim > 30 { + return Err(format!("PCMPS-TN null-space dim {null_dim} > 30")); + } + + // Build null-space basis vectors. Pack as bitmasks: + // - For n ≤ 32 (n_bits ≤ 64): single u128 per basis vector. + // - Otherwise: Vec. + // Per-site weight lookup then becomes a single shift+mask. + let basis_u128: Option> = if n_bits <= 128 { + Some( + free_cols + .iter() + .map(|&f| { + let mut bits: u128 = 1u128 << f; + for rr in 0..rank { + if let Some(p) = pivot_col_of_row[rr] + && a_rows[rr][f] + { + bits ^= 1u128 << p; + } + } + bits + }) + .collect(), + ) + } else { + None + }; + + let total_combos = 1usize << null_dim; + + let accumulate_combo_u128 = |basis_masks: &[u128], combo: usize| -> f64 { + let mut bits: u128 = 0; + for (k, &mask) in basis_masks.iter().enumerate() { + if (combo >> k) & 1 == 1 { + bits ^= mask; + } + } + let mut w: f64 = 1.0; + for (j, wj) in weights.iter().enumerate() { + let idx = ((bits >> (2 * j)) & 0b11) as usize; + w *= wj[idx]; + if w == 0.0 { + return 0.0; + } + } + w + }; + + let tr_sq: f64 = if let Some(basis_masks) = basis_u128.as_ref() { + use rayon::prelude::*; + if total_combos >= (1 << 14) { + (0..total_combos) + .into_par_iter() + .map(|combo| accumulate_combo_u128(basis_masks, combo)) + .sum() + } else { + (0..total_combos) + .map(|combo| accumulate_combo_u128(basis_masks, combo)) + .sum() + } + } else { + // Fall back: boolean-vector enumeration (slow but correct for n > 64). + let mut basis: Vec> = Vec::with_capacity(null_dim); + for &f in &free_cols { + let mut v = vec![false; n_bits]; + v[f] = true; + for rr in 0..rank { + if let Some(p) = pivot_col_of_row[rr] + && a_rows[rr][f] + { + v[p] = true; + } + } + basis.push(v); + } + let mut sum: f64 = 0.0; + for combo in 0..total_combos { + let mut bits = vec![false; n_bits]; + for (k, bk) in basis.iter().enumerate() { + if (combo >> k) & 1 == 1 { + for (bi, &bki) in bits.iter_mut().zip(bk.iter()) { + *bi ^= bki; + } + } + } + let mut w: f64 = 1.0; + for j in 0..n { + let x = bits[2 * j]; + let z = bits[2 * j + 1]; + let idx = usize::from(x) | (usize::from(z) << 1); + w *= weights[j][idx]; + if w == 0.0 { + break; + } + } + sum += w; + } + sum + }; + let tr_sq = tr_sq / f64::from(1u32 << u32::try_from(n_a).unwrap()); + + if tr_sq < 1e-30 { + Ok(f64::INFINITY) + } else { + Ok(-tr_sq.ln()) + } +} + +/// Faster `S_2` via GF(2) null-space enumeration (PCMPS-style). +/// +/// Applicable when every MPS site has exactly ONE non-zero Bloch component +/// (i.e. lies on a Pauli axis). Most STN Clifford+T states satisfy this +/// because T gates absorb into the tableau, leaving MPS sites as |0⟩ (Z-axis). +/// +/// Algorithm: +/// 1. Each site j contributes one binary variable `v_j` ∈ {0,1} (I vs `P_j`). +/// 2. Support-on-A constraint on (C·P·C†) is a system of linear equations +/// in `v_j` over GF(2). +/// 3. Enumerate only the null space (dim d), not 2^N combos — 2^d evaluations. +/// +/// For single-axis states this is typically d ≈ `N_A`, i.e. `2^{N_A`} not 2^N. +/// Returns error if any site has multi-axis Bloch (caller can fall back to PCE). +/// +/// # Errors +/// +/// Returns an error string if the mask length doesn't match the MPS, if any +/// site has multi-axis Bloch vectors, or if the null-space exceeds the +/// enumeration limit. +/// +/// # Panics +/// +/// Panics if the region-A or null-space size exceeds i16 range. +pub fn compute_s2_pcmps( + mps: &Mps, + tableau: &SparseStabY, + region_a_mask: &[bool], +) -> Result { + let n = mps.num_sites(); + if region_a_mask.len() != n { + return Err("region_a_mask length mismatch".into()); + } + let bvs = bloch_vectors(mps)?; + let tol = 1e-12; + + // Per-site single-axis variable: (bloch_coef, mapped_pauli_string). + // Fail fast if any site has ≥ 2 non-zero Bloch components. + let mut vars: Vec<(f64, PauliString)> = Vec::with_capacity(n); + for (j, &(rx, ry, rz)) in bvs.iter().enumerate() { + let cands = [(rx, 'X'), (ry, 'Y'), (rz, 'Z')]; + let nonzero: Vec<&(f64, char)> = cands.iter().filter(|(r, _)| r.abs() > tol).collect(); + if nonzero.len() != 1 { + return Err(format!( + "PCMPS needs 1 non-zero Bloch axis per site; site {j} has {} (rx={rx}, ry={ry}, rz={rz})", + nonzero.len() + )); + } + let (r, p) = *nonzero[0]; + vars.push((r, map_pauli_through_tableau(tableau, j, p, 1.0))); + } + + // Build GF(2) constraint matrix A (rows = B-site bit constraints, cols = vars). + // For each B site q, two rows (x-bit, z-bit) constraining the combined Pauli + // to have 0 at that bit position. + let n_vars = vars.len(); + let mut a_rows: Vec> = Vec::new(); + for (q, &is_a) in region_a_mask.iter().enumerate() { + if is_a { + continue; + } + let row_x: Vec = vars.iter().map(|v| v.1.x[q]).collect(); + let row_z: Vec = vars.iter().map(|v| v.1.z[q]).collect(); + if row_x.iter().any(|&b| b) { + a_rows.push(row_x); + } + if row_z.iter().any(|&b| b) { + a_rows.push(row_z); + } + } + + // Gauss-eliminate to RREF; record pivot cols and free cols. + let n_rows = a_rows.len(); + let mut pivot_col_of_row: Vec> = vec![None; n_rows]; + let mut col_is_pivot: Vec = vec![false; n_vars]; + let mut r = 0; + for c in 0..n_vars { + if r >= n_rows { + break; + } + let found = a_rows[r..] + .iter() + .position(|row| row[c]) + .map(|offset| r + offset); + if let Some(rr) = found { + a_rows.swap(r, rr); + let pivot_row = a_rows[r].clone(); + for (rr, row) in a_rows.iter_mut().enumerate() { + if rr != r && row[c] { + for (cell, &piv) in row.iter_mut().zip(pivot_row.iter()) { + *cell ^= piv; + } + } + } + pivot_col_of_row[r] = Some(c); + col_is_pivot[c] = true; + r += 1; + } + } + let rank = r; + let free_cols: Vec = (0..n_vars).filter(|&c| !col_is_pivot[c]).collect(); + let null_dim = free_cols.len(); + debug_assert_eq!(rank + null_dim, n_vars); + + let n_a: usize = region_a_mask.iter().filter(|&&b| b).count(); + + // Short-circuit: all-Clifford states have |var_coef · ps.coef| = 1 at every + // variable. Then every null-space combination contributes coef² = 1, + // so tr_sq = 2^null_dim / 2^N_A. + let all_clifford = vars + .iter() + .all(|(r, ps)| (r.abs() * ps.coef.abs() - 1.0).abs() < 1e-9); + if all_clifford { + let diff = i16::try_from(null_dim).expect("null_dim fits in i16") + - i16::try_from(n_a).expect("n_a fits in i16"); + let s2 = -f64::from(diff) * (2.0f64).ln(); + return Ok(s2); + } + + if null_dim > 22 { + return Err(format!( + "PCMPS null-space dim {null_dim} > 22 (non-Clifford)" + )); + } + + // Null-space basis: for each free col f, basis vector e_f has v_f = 1 and + // v_p = A[r_p][f] for each pivot row r_p (pivot col p). + let mut basis: Vec> = Vec::with_capacity(null_dim); + for &f in &free_cols { + let mut v = vec![false; n_vars]; + v[f] = true; + for rr in 0..rank { + if let Some(p) = pivot_col_of_row[rr] + && a_rows[rr][f] + { + v[p] = true; + } + } + basis.push(v); + } + + // Enumerate 2^null_dim combinations of basis vectors; for each, compute + // product coefficient and accumulate coef². + let total_combos = 1usize << null_dim; + let mut tr_sq: f64 = 0.0; + for combo in 0..total_combos { + // XOR combination of basis vectors selected by bits of combo. + let mut selection = vec![false; n_vars]; + for (k, bk) in basis.iter().enumerate() { + if (combo >> k) & 1 == 1 { + for (sel, &bki) in selection.iter_mut().zip(bk.iter()) { + *sel ^= bki; + } + } + } + // Compute combined Pauli string and coefficient. + let mut cx = vec![false; n]; + let mut cz = vec![false; n]; + let mut coef: f64 = 1.0; + let mut mc: u32 = 0; + let mut ic: u32 = 0; + for (i, sel) in selection.iter().enumerate() { + if !sel { + continue; + } + let (bloch, ps) = &vars[i]; + coef *= bloch * ps.coef; + for q in 0..n { + let pa = pauli_idx(cx[q], cz[q]); + let pb = pauli_idx(ps.x[q], ps.z[q]); + let (m, i_b) = pauli_phase(pa, pb); + mc += u32::from(m); + ic += u32::from(i_b); + cx[q] ^= ps.x[q]; + cz[q] ^= ps.z[q]; + } + } + debug_assert_eq!(ic % 2, 0, "null-space combos must give even i-count"); + if (ic / 2 + mc) % 2 == 1 { + coef = -coef; + } + debug_assert!( + cx.iter() + .zip(&cz) + .enumerate() + .all(|(q, (x, z))| region_a_mask[q] || (!x && !z)), + "null-space vector violated support constraint (GF(2) bug)" + ); + tr_sq += coef * coef; + } + // n_a is bounded by the number of qubits (enforced by early checks) so n_a <= 22. + tr_sq *= 0.5_f64.powi(i32::from(u16::try_from(n_a).expect("n_a fits in u16"))); + + if tr_sq < 1e-30 { + Ok(f64::INFINITY) + } else { + Ok(-tr_sq.ln()) + } +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::stab_mps::StabMps; + use pecos_core::QubitId; + use pecos_simulators::CliffordGateable; + + #[test] + fn test_bloch_vector_zero_state() { + let stn = StabMps::new(3); + let bvs = bloch_vectors(stn.mps()).unwrap(); + // |0⟩ state: (0, 0, +1). + for (rx, ry, rz) in bvs { + assert!((rx - 0.0).abs() < 1e-9); + assert!((ry - 0.0).abs() < 1e-9); + assert!((rz - 1.0).abs() < 1e-9); + } + } + + #[test] + fn test_pauli_string_supported_on() { + let mut p = PauliString::identity(4); + p.x[0] = true; + p.z[1] = true; + let region_a = vec![true, true, false, false]; + assert!(p.supported_on(®ion_a)); + p.x[2] = true; + assert!(!p.supported_on(®ion_a)); + } + + #[test] + fn test_map_pauli_identity_tableau() { + // Trivial tableau (identity Clifford): C P C† = P. + // X at site 0 maps to X_0 on all qubits. + let stn = StabMps::new(3); + let g = map_pauli_through_tableau(stn.tableau(), 0, 'X', 1.0); + assert!(g.x[0] && !g.z[0]); + assert!(!g.x[1] && !g.z[1]); + assert!(!g.x[2] && !g.z[2]); + assert!((g.coef - 1.0).abs() < 1e-9); + + // Z at site 1. + let g = map_pauli_through_tableau(stn.tableau(), 1, 'Z', 1.0); + assert!(!g.x[1] && g.z[1]); + assert!(!g.x[0] && !g.z[0]); + } + + #[test] + fn test_pce_s2_zero_state() { + // |0⟩^N: all stabilized by Z_j. S_2 = 0 for any bipartition. + let stn = StabMps::new(4); + let mask = vec![true, true, false, false]; + let s2 = compute_s2_pce(stn.mps(), stn.tableau(), &mask).unwrap(); + eprintln!("zero state S_2 = {s2}"); + assert!(s2.abs() < 1e-9, "zero state should have S_2=0, got {s2}"); + } + + #[test] + fn test_pce_s2_bell_state() { + // Bell state: S_2 = ln(2). + let mut stn = StabMps::new(2); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + let mask = vec![true, false]; // q0 in A, q1 in B + let s2 = compute_s2_pce(stn.mps(), stn.tableau(), &mask).unwrap(); + eprintln!("Bell S_2 (PCE) = {s2}, expected ln(2) = {}", (2.0f64).ln()); + assert!((s2 - (2.0f64).ln()).abs() < 1e-9); + } + + #[test] + fn test_pce_matches_sv_for_clifford_plus_t() { + use pecos_core::Angle64; + use pecos_simulators::ArbitraryRotationGateable; + // H on all, CX, T on q0 (creates entangled magic state), + // CX between regions. Real Clifford+T circuit. + let mut stn = StabMps::new(4); + stn.h(&[QubitId(0), QubitId(1), QubitId(2), QubitId(3)]); + stn.cx(&[(QubitId(0), QubitId(2))]); // entangle A-B boundary + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); // T on q0 + stn.cx(&[(QubitId(1), QubitId(3))]); // entangle more + let mask = vec![true, true, false, false]; // A = {0,1}, B = {2,3} + + let s2_pce = compute_s2_pce(stn.mps(), stn.tableau(), &mask).unwrap(); + let s2_sv = stn.renyi_s2(2); + eprintln!("PCE: {s2_pce:.6}, SV: {s2_sv:.6}"); + assert!( + (s2_pce - s2_sv).abs() < 1e-6, + "PCE should match SV now that Y-sign is tracked: PCE={s2_pce} SV={s2_sv}" + ); + } + + #[test] + fn test_pce_entangled_clifford_plus_t() { + // Genuinely entangled Clifford+T across A-B boundary. + use pecos_core::Angle64; + use pecos_simulators::ArbitraryRotationGateable; + let mut stn = StabMps::new(4); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(2))]); // Bell across A-B + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(2)]); // T on B-side + stn.h(&[QubitId(1)]); + stn.cx(&[(QubitId(1), QubitId(3))]); // second Bell across A-B + let mask = vec![true, true, false, false]; + let s2_pce = compute_s2_pce(stn.mps(), stn.tableau(), &mask).unwrap(); + let s2_sv = stn.renyi_s2(2); + eprintln!("entangled PCE: {s2_pce:.6}, SV: {s2_sv:.6}"); + assert!( + (s2_pce - s2_sv).abs() < 1e-6, + "PCE should match SV for entangled Clifford+T: PCE={s2_pce} SV={s2_sv}" + ); + assert!(s2_pce > 0.5, "expected non-trivial entanglement"); + } + + #[test] + fn test_map_pauli_after_cx() { + // C = CX(0,1). Z_0 unchanged, Z_1 -> Z_0 Z_1, X_0 -> X_0 X_1, X_1 unchanged. + let mut stn = StabMps::new(2); + stn.cx(&[(QubitId(0), QubitId(1))]); + let gz0 = map_pauli_through_tableau(stn.tableau(), 0, 'Z', 1.0); + assert!(!gz0.x[0] && gz0.z[0]); // Z_0 + assert!(!gz0.x[1] && !gz0.z[1]); + let gz1 = map_pauli_through_tableau(stn.tableau(), 1, 'Z', 1.0); + assert!(!gz1.x[0] && gz1.z[0]); // Z_0 + assert!(!gz1.x[1] && gz1.z[1]); // Z_1 + let gx0 = map_pauli_through_tableau(stn.tableau(), 0, 'X', 1.0); + assert!(gx0.x[0] && !gx0.z[0]); // X_0 + assert!(gx0.x[1] && !gx0.z[1]); // X_1 + } +} diff --git a/exp/pecos-stab-tn/src/stab_mps/tableau_compose.rs b/exp/pecos-stab-tn/src/stab_mps/tableau_compose.rs new file mode 100644 index 000000000..77572337d --- /dev/null +++ b/exp/pecos-stab-tn/src/stab_mps/tableau_compose.rs @@ -0,0 +1,1006 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Right-composition of Clifford gates onto a stabilizer tableau. +//! +//! The existing `SparseStabY` gate methods (h, sz, cx) perform LEFT-composition: +//! they transform C into G*C, conjugating each generator by G acting on physical +//! qubits. Right-composition transforms C into C*G, which acts on the "virtual" +//! side -- the generator rows themselves. +//! +//! Mathematical identity: +//! - Left-compose by G: stabilizer `S_k` = C `Z_k` C^dagger -> G `S_k` G^dagger +//! - Right-compose by G: `S_k` -> C (G `Z_k` G^dagger) C^dagger +//! +//! Right-composition is what the stabilizer-TN reference uses to absorb the +//! compensating CNOT cascade from the exact disentangling path. This allows +//! the disentangling to leave the MPS in a single-site rotation state without +//! needing the full multi-site CNOT cascade on the MPS. +//! +//! Implementation for each gate (right-compose): +//! - `H_q`: swap stabs row q with destabs row q (and their signs) +//! - `S_q`: destabs[q] *= stabs[q], with phase +i correction +//! - CX(c,t): stabs[t] *= stabs[c], destabs[c] *= destabs[t] +//! +//! Reference: Aaronson & Gottesman, "Improved Simulation of Stabilizer Circuits" +//! (PRA 70, 052328 (2004)); stabilizer-TN reference compose(..., front=True). + +use num_complex::Complex64; +use pecos_core::{BitSet, IndexSet}; +use pecos_simulators::{GensGeneric, SparseStabY}; + +/// Standard Pauli multiplication phase table (Y=iXZ). Index scheme: +/// I=0, Z=1, X=2, Y=3. +/// Returns (`minus_bit`, `i_bit`) for the phase factor of `Pauli_a` · `Pauli_b`. +/// Encoding: +1=(0,0), -1=(1,0), +i=(0,1), -i=(1,1). +const fn pauli_phase(a: u8, b: u8) -> (i8, i8) { + match (a, b) { + (1, 2) | (3, 1) | (2, 3) => (0, 1), // +i: Z·X, Y·Z, X·Y + (2, 1) | (1, 3) | (3, 2) => (1, 1), // -i: X·Z, Z·Y, Y·X + _ => (0, 0), // I or same Pauli + } +} + +/// Compute Pauli index (0=I, 1=Z, 2=X, 3=Y) from (x, z) bits. +const fn pauli_idx(x: bool, z: bool) -> u8 { + match (x, z) { + (false, false) => 0, // I + (false, true) => 1, // Z + (true, false) => 2, // X + (true, true) => 3, // Y + } +} + +/// Multiply row `a` by row `b` in place: a *= b. +/// +/// Result: `a.row_x` = `a.row_x` XOR `b.row_x` +/// `a.row_z` = `a.row_z` XOR `b.row_z` +/// a.sign *= b.sign * (product of per-qubit phases) +/// +/// Both rows are treated as Y-convention Pauli strings with optional signs. +pub(crate) fn multiply_row( + gens_a: &mut GensGeneric, + row_a: usize, + gens_b: &GensGeneric, + row_b: usize, + num_qubits: usize, +) { + // Compute per-qubit phase contribution + let mut phase = Complex64::new(1.0, 0.0); + for q in 0..num_qubits { + let a_x = gens_a.row_x[row_a].contains(q); + let a_z = gens_a.row_z[row_a].contains(q); + let b_x = gens_b.row_x[row_b].contains(q); + let b_z = gens_b.row_z[row_b].contains(q); + + if !a_x && !a_z { + continue; + } // I * anything, no phase + if !b_x && !b_z { + continue; + } // anything * I, no phase + + let pa = pauli_idx(a_x, a_z); + let pb = pauli_idx(b_x, b_z); + let (minus, i_bit) = pauli_phase(pa, pb); + if minus == 1 { + phase *= Complex64::new(-1.0, 0.0); + } + if i_bit == 1 { + phase *= Complex64::new(0.0, 1.0); + } + } + + // Update row a's bit vectors: XOR with row b + let b_row_x = gens_b.row_x[row_b].clone(); + let b_row_z = gens_b.row_z[row_b].clone(); + + // Update col_x and col_z columns based on the XOR + for q in b_row_x.iter() { + gens_a.col_x[q].toggle(row_a); + } + for q in b_row_z.iter() { + gens_a.col_z[q].toggle(row_a); + } + + gens_a.row_x[row_a].xor_assign(&b_row_x); + gens_a.row_z[row_a].xor_assign(&b_row_z); + + // Combine signs: a.sign *= b.sign * phase + let b_minus = gens_b.signs_minus.contains(row_b); + let b_i = gens_b.signs_i.contains(row_b); + if b_minus { + phase *= Complex64::new(-1.0, 0.0); + } + if b_i { + phase *= Complex64::new(0.0, 1.0); + } + + // Apply phase to row_a's signs + let a_minus = gens_a.signs_minus.contains(row_a); + let a_i = gens_a.signs_i.contains(row_a); + // Current sign of a is (a_minus, a_i). New sign = old * phase. + let old_sign = match (a_minus, a_i) { + (false, false) => Complex64::new(1.0, 0.0), + (true, false) => Complex64::new(-1.0, 0.0), + (false, true) => Complex64::new(0.0, 1.0), + (true, true) => Complex64::new(0.0, -1.0), + }; + let new_sign = old_sign * phase; + + // Round to nearest (minus, i) combination + let (new_minus, new_i) = if (new_sign - Complex64::new(1.0, 0.0)).norm() < 1e-9 { + (false, false) + } else if (new_sign - Complex64::new(-1.0, 0.0)).norm() < 1e-9 { + (true, false) + } else if (new_sign - Complex64::new(0.0, 1.0)).norm() < 1e-9 { + (false, true) + } else if (new_sign - Complex64::new(0.0, -1.0)).norm() < 1e-9 { + (true, true) + } else { + panic!("row multiplication produced non-quarter-phase: {new_sign}"); + }; + + if new_minus != a_minus { + gens_a.signs_minus.toggle(row_a); + } + if new_i != a_i { + gens_a.signs_i.toggle(row_a); + } +} + +/// Swap rows between two `GensGeneric` structures. +/// +/// Swaps row `row_a` of `gens_a` with row `row_b` of `gens_b`, including +/// the bit vectors (`row_x`, `row_z`) and the signs. Also updates `col_x/col_z`. +fn swap_rows_between( + gens_a: &mut GensGeneric, + row_a: usize, + gens_b: &mut GensGeneric, + row_b: usize, +) { + // Swap bit vectors + std::mem::swap(&mut gens_a.row_x[row_a], &mut gens_b.row_x[row_b]); + std::mem::swap(&mut gens_a.row_z[row_a], &mut gens_b.row_z[row_b]); + + // Update col_x/col_z consistency + // After swap: for each qubit q, toggle col_x[q] membership in row_a and row_b + // based on the new row_x contents. Do this by recomputing from the row contents. + // + // Actually, the col representation must remain consistent. The row contents + // swapped, so we need to: + // - For gens_a: the qubits in row_a's NEW row_x are those that were in gens_b's row_b + // before swap. But gens_a.col_x is indexed by qubit and contains row indices within gens_a. + // So for each qubit q: + // - If row_a was previously in col_x[q] but isn't in gens_a.row_x[row_a] anymore, remove. + // - If row_a wasn't but is now, add. + // The "now" content is what was in gens_b.row_x[row_b] before swap (= gens_a.row_x[row_a] after swap). + // + // Simplest: after swapping row_x bit vectors, rebuild the cols for row_a in gens_a and row_b in gens_b. + // + // For each qubit q: check if gens_a.row_x[row_a].contains(q) == gens_a.col_x[q].contains(row_a). + // If mismatch, toggle col_x[q] membership of row_a. Similar for row_z, row_b, etc. + + let num_qubits = gens_a.col_x.len(); + for q in 0..num_qubits { + // gens_a row_a + let row_x_has = gens_a.row_x[row_a].contains(q); + let col_x_has = gens_a.col_x[q].contains(row_a); + if row_x_has != col_x_has { + gens_a.col_x[q].toggle(row_a); + } + let row_z_has = gens_a.row_z[row_a].contains(q); + let col_z_has = gens_a.col_z[q].contains(row_a); + if row_z_has != col_z_has { + gens_a.col_z[q].toggle(row_a); + } + // gens_b row_b + let row_x_has = gens_b.row_x[row_b].contains(q); + let col_x_has = gens_b.col_x[q].contains(row_b); + if row_x_has != col_x_has { + gens_b.col_x[q].toggle(row_b); + } + let row_z_has = gens_b.row_z[row_b].contains(q); + let col_z_has = gens_b.col_z[q].contains(row_b); + if row_z_has != col_z_has { + gens_b.col_z[q].toggle(row_b); + } + } + + // Swap signs + let a_minus = gens_a.signs_minus.contains(row_a); + let b_minus = gens_b.signs_minus.contains(row_b); + if a_minus != b_minus { + gens_a.signs_minus.toggle(row_a); + gens_b.signs_minus.toggle(row_b); + } + let a_i = gens_a.signs_i.contains(row_a); + let b_i = gens_b.signs_i.contains(row_b); + if a_i != b_i { + gens_a.signs_i.toggle(row_a); + gens_b.signs_i.toggle(row_b); + } +} + +/// Right-compose Hadamard gate on qubit q onto the tableau. +/// +/// Semantically: C -> C * `H_q`. +/// +/// For each stabilizer/destabilizer row, this transforms `Z_k` -> (`H_q` `Z_k` `H_q`). +/// `H_q` `Z_q` `H_q` = `X_q`, so `S_q`' = C `X_q` C^dagger = `D_q` (old destabilizer). +/// `H_q` `Z_k` `H_q` = `Z_k` for k != q (unchanged). +/// Similarly for destabilizers: `H_q` `X_q` `H_q` = `Z_q`, so `D_q`' = old `S_q`. +/// +/// Implementation: swap stabs row q with destabs row q. +pub fn right_compose_h( + tableau: &mut SparseStabY, + q: usize, +) { + let (stabs, destabs) = tableau.stabs_and_destabs_mut(); + swap_rows_between(stabs, q, destabs, q); +} + +/// Right-compose `S_z` (phase) gate on qubit q onto the tableau. +/// +/// `S_z` `Z_q` `S_z^dagger` = `Z_q` (unchanged), so stabilizers unchanged. +/// `S_z` `X_q` `S_z^dagger` = `Y_q` = iXZ, so `D_q`' = i * `D_q` * `S_q`. +/// +/// Implementation: destabs row q *= stabs row q (with phase +i). +/// +/// # Panics +/// +/// Panics if the resulting phase is not a quarter-phase (indicates a bug in +/// the phase-tracking logic). +pub fn right_compose_sz( + tableau: &mut SparseStabY, + q: usize, +) { + let num_qubits = tableau.num_qubits(); + // D_q' = i * D_q * S_q + // Multiply destabs row q by stabs row q (get D_q * S_q) + let stabs_snapshot_x = tableau.stabs().row_x[q].clone(); + let stabs_snapshot_z = tableau.stabs().row_z[q].clone(); + let stabs_minus = tableau.stabs().signs_minus.contains(q); + let stabs_i = tableau.stabs().signs_i.contains(q); + + // Compute per-qubit phase of D_q * S_q (using snapshot of stabs row q) + let destabs = tableau.destabs(); + let mut phase = Complex64::new(1.0, 0.0); + for qq in 0..num_qubits { + let a_x = destabs.row_x[q].contains(qq); + let a_z = destabs.row_z[q].contains(qq); + let b_x = stabs_snapshot_x.contains(qq); + let b_z = stabs_snapshot_z.contains(qq); + if (!a_x && !a_z) || (!b_x && !b_z) { + continue; + } + let pa = pauli_idx(a_x, a_z); + let pb = pauli_idx(b_x, b_z); + let (minus, i_bit) = pauli_phase(pa, pb); + if minus == 1 { + phase *= Complex64::new(-1.0, 0.0); + } + if i_bit == 1 { + phase *= Complex64::new(0.0, 1.0); + } + } + // Include stabs sign + if stabs_minus { + phase *= Complex64::new(-1.0, 0.0); + } + if stabs_i { + phase *= Complex64::new(0.0, 1.0); + } + // Multiply by i (the S_z phase) + phase *= Complex64::new(0.0, 1.0); + + // Now update destabs row q: XOR bits with stabs row q, apply accumulated phase + let destabs_mut = tableau.destabs_mut(); + + // Update col_x/col_z + for qq in &stabs_snapshot_x { + destabs_mut.col_x[qq].toggle(q); + } + for qq in &stabs_snapshot_z { + destabs_mut.col_z[qq].toggle(q); + } + destabs_mut.row_x[q].xor_assign(&stabs_snapshot_x); + destabs_mut.row_z[q].xor_assign(&stabs_snapshot_z); + + // Update sign + let d_minus = destabs_mut.signs_minus.contains(q); + let d_i = destabs_mut.signs_i.contains(q); + let old_sign = match (d_minus, d_i) { + (false, false) => Complex64::new(1.0, 0.0), + (true, false) => Complex64::new(-1.0, 0.0), + (false, true) => Complex64::new(0.0, 1.0), + (true, true) => Complex64::new(0.0, -1.0), + }; + let new_sign = old_sign * phase; + let (new_minus, new_i) = if (new_sign - Complex64::new(1.0, 0.0)).norm() < 1e-9 { + (false, false) + } else if (new_sign - Complex64::new(-1.0, 0.0)).norm() < 1e-9 { + (true, false) + } else if (new_sign - Complex64::new(0.0, 1.0)).norm() < 1e-9 { + (false, true) + } else if (new_sign - Complex64::new(0.0, -1.0)).norm() < 1e-9 { + (true, true) + } else { + panic!("right_compose_sz produced non-quarter-phase: {new_sign}"); + }; + if new_minus != d_minus { + destabs_mut.signs_minus.toggle(q); + } + if new_i != d_i { + destabs_mut.signs_i.toggle(q); + } +} + +/// Right-compose CX(control, target) gate onto the tableau. +/// +/// CX(c, t) acting on the right: +/// - `Z_c` unchanged -> stabs[c] unchanged +/// - `Z_t` -> `Z_c` `Z_t` -> stabs[t] *= stabs[c] +/// - `X_c` -> `X_c` `X_t` -> destabs[c] *= destabs[t] +/// - `X_t` unchanged -> destabs[t] unchanged +pub fn right_compose_cx( + tableau: &mut SparseStabY, + control: usize, + target: usize, +) { + debug_assert_ne!(control, target, "CX requires distinct qubits"); + let num_qubits = tableau.num_qubits(); + + // stabs[t] *= stabs[c] (multiply within stabs, self-reference) + { + let stabs = tableau.stabs_mut(); + multiply_row_within(stabs, target, control, num_qubits); + } + + // destabs[c] *= destabs[t] + { + let destabs = tableau.destabs_mut(); + multiply_row_within(destabs, control, target, num_qubits); + } +} + +/// Right-compose `S_z^dagger` (inverse phase) gate onto the tableau. +/// +/// Sdg Z Sdg^dagger = Z (unchanged), Sdg X Sdg^dagger = -Y = -iXZ. +/// So destabs[q] gets multiplied by stabs[q] with a -i phase. +pub fn right_compose_szdg( + tableau: &mut SparseStabY, + q: usize, +) { + let num_qubits = tableau.num_qubits(); + let stabs_snapshot_x = tableau.stabs().row_x[q].clone(); + let stabs_snapshot_z = tableau.stabs().row_z[q].clone(); + let stabs_minus = tableau.stabs().signs_minus.contains(q); + let stabs_i = tableau.stabs().signs_i.contains(q); + + let destabs = tableau.destabs(); + let mut phase = Complex64::new(1.0, 0.0); + for qq in 0..num_qubits { + let a_x = destabs.row_x[q].contains(qq); + let a_z = destabs.row_z[q].contains(qq); + let b_x = stabs_snapshot_x.contains(qq); + let b_z = stabs_snapshot_z.contains(qq); + if (!a_x && !a_z) || (!b_x && !b_z) { + continue; + } + let pa = pauli_idx(a_x, a_z); + let pb = pauli_idx(b_x, b_z); + let (minus, i_bit) = pauli_phase(pa, pb); + if minus == 1 { + phase *= Complex64::new(-1.0, 0.0); + } + if i_bit == 1 { + phase *= Complex64::new(0.0, 1.0); + } + } + if stabs_minus { + phase *= Complex64::new(-1.0, 0.0); + } + if stabs_i { + phase *= Complex64::new(0.0, 1.0); + } + // Multiply by -i (Sdg phase) + phase *= Complex64::new(0.0, -1.0); + + let destabs_mut = tableau.destabs_mut(); + for qq in &stabs_snapshot_x { + destabs_mut.col_x[qq].toggle(q); + } + for qq in &stabs_snapshot_z { + destabs_mut.col_z[qq].toggle(q); + } + destabs_mut.row_x[q].xor_assign(&stabs_snapshot_x); + destabs_mut.row_z[q].xor_assign(&stabs_snapshot_z); + + apply_phase_to_sign(destabs_mut, q, phase); +} + +/// Right-compose X gate on qubit q onto the tableau. +/// +/// X Z X = -Z, X X X = X. So stabs[q] sign flips, destabs[q] unchanged. +pub fn right_compose_x( + tableau: &mut SparseStabY, + q: usize, +) { + // X conjugates Z to -Z, so stabs[q] (which is C Z_q C^dagger) becomes C (-Z_q) C^dagger + // Result: flip sign of stabs row q. + let stabs = tableau.stabs_mut(); + stabs.signs_minus.toggle(q); +} + +/// Right-compose Z gate on qubit q onto the tableau. +/// +/// Z Z Z = Z, Z X Z = -X. So destabs[q] sign flips, stabs[q] unchanged. +pub fn right_compose_z( + tableau: &mut SparseStabY, + q: usize, +) { + let destabs = tableau.destabs_mut(); + destabs.signs_minus.toggle(q); +} + +/// Right-compose CY(control, target) gate onto the tableau. +/// +/// CY = (I ⊗ Sdg) · CX · (I ⊗ S) when acting on state (circuit-order first-to-last: S, CX, Sdg). +/// Verify: S · X · Sdg = Y (confirmed by matrix calculation). +/// +/// For right-composition (C' = C * U): U = Sdg · CX · S (matrix form, since virtual-side +/// circuit order is reverse of matrix product direction). No wait -- read carefully: +/// If right-compose applies U to virtual side BEFORE C, then virtual-side circuit order +/// for U = Sdg · CX · S is: S first, then CX, then Sdg. But that's not what we want. +/// +/// Let me restate: we want the VIRTUAL op to be CY = (in circuit order on virtual) S, CX, Sdg. +/// For this, the right-compose sequence is: call Sdg FIRST, then CX, then S. +/// Why? Each `right_compose_X(U)` multiplies C by U on the right: C := C * U. +/// After calls [A, B, C]: tableau = ((`C_init` * A) * B) * C = `C_init` * A * B * C. +/// Read as matrix: virtual op applied first is C (rightmost), then B, then A. +/// So for virtual circuit "S, CX, Sdg" (S first), we need matrix A·B·C = Sdg·CX·S, +/// which means call sequence: Sdg, CX, S. +pub fn right_compose_cy( + tableau: &mut SparseStabY, + control: usize, + target: usize, +) { + right_compose_szdg(tableau, target); + right_compose_cx(tableau, control, target); + right_compose_sz(tableau, target); +} + +/// Right-compose CZ(q1, q2) gate onto the tableau. +/// +/// CZ = `H_2` CX(1,2) `H_2`. The effect on generators: +/// - `Z_1` -> `Z_1`, `Z_2` -> `Z_2` (stabs unchanged) +/// - `X_1` -> `X_1` `Z_2` (destabs[1] *= stabs[2]) +/// - `X_2` -> `Z_1` `X_2` (destabs[2] *= stabs[1]) +pub fn right_compose_cz( + tableau: &mut SparseStabY, + q1: usize, + q2: usize, +) { + debug_assert_ne!(q1, q2, "CZ requires distinct qubits"); + let num_qubits = tableau.num_qubits(); + + // destabs[q1] *= stabs[q2] (X_1 -> X_1 Z_2 means D_1 gets a Z_2 factor = S_2) + multiply_row_across(tableau, q1, q2, num_qubits, /*dest_to_stab=*/ true); + // destabs[q2] *= stabs[q1] + multiply_row_across(tableau, q2, q1, num_qubits, /*dest_to_stab=*/ true); +} + +/// Multiply row `dst_row` by row `src_row` within the same generator set. +fn multiply_row_within( + gens: &mut GensGeneric, + dst_row: usize, + src_row: usize, + num_qubits: usize, +) { + // Snapshot source row + let src_x = gens.row_x[src_row].clone(); + let src_z = gens.row_z[src_row].clone(); + let src_minus = gens.signs_minus.contains(src_row); + let src_i = gens.signs_i.contains(src_row); + + // Compute phase + let mut phase = Complex64::new(1.0, 0.0); + for q in 0..num_qubits { + let a_x = gens.row_x[dst_row].contains(q); + let a_z = gens.row_z[dst_row].contains(q); + let b_x = src_x.contains(q); + let b_z = src_z.contains(q); + if (!a_x && !a_z) || (!b_x && !b_z) { + continue; + } + let pa = pauli_idx(a_x, a_z); + let pb = pauli_idx(b_x, b_z); + let (minus, i_bit) = pauli_phase(pa, pb); + if minus == 1 { + phase *= Complex64::new(-1.0, 0.0); + } + if i_bit == 1 { + phase *= Complex64::new(0.0, 1.0); + } + } + if src_minus { + phase *= Complex64::new(-1.0, 0.0); + } + if src_i { + phase *= Complex64::new(0.0, 1.0); + } + + // Update col_x/col_z + for q in src_x.iter() { + gens.col_x[q].toggle(dst_row); + } + for q in src_z.iter() { + gens.col_z[q].toggle(dst_row); + } + gens.row_x[dst_row].xor_assign(&src_x); + gens.row_z[dst_row].xor_assign(&src_z); + + // Apply accumulated phase to dst_row's sign + apply_phase_to_sign(gens, dst_row, phase); +} + +/// Multiply destabs[`dst_q`] by stabs[`src_q`] (or vice versa). +/// `dest_to_stab`: if true, dst is destabs and src is stabs. +fn multiply_row_across( + tableau: &mut SparseStabY, + dst_q: usize, + src_q: usize, + num_qubits: usize, + dest_to_stab: bool, +) { + if !dest_to_stab { + unimplemented!("only dest_to_stab=true is used here"); + } + // Snapshot source row (from stabs) + let src_x = tableau.stabs().row_x[src_q].clone(); + let src_z = tableau.stabs().row_z[src_q].clone(); + let src_minus = tableau.stabs().signs_minus.contains(src_q); + let src_i = tableau.stabs().signs_i.contains(src_q); + + // Compute phase using destabs[dst_q] (destination) and stabs[src_q] (source) + let destabs = tableau.destabs(); + let mut phase = Complex64::new(1.0, 0.0); + for q in 0..num_qubits { + let a_x = destabs.row_x[dst_q].contains(q); + let a_z = destabs.row_z[dst_q].contains(q); + let b_x = src_x.contains(q); + let b_z = src_z.contains(q); + if (!a_x && !a_z) || (!b_x && !b_z) { + continue; + } + let pa = pauli_idx(a_x, a_z); + let pb = pauli_idx(b_x, b_z); + let (minus, i_bit) = pauli_phase(pa, pb); + if minus == 1 { + phase *= Complex64::new(-1.0, 0.0); + } + if i_bit == 1 { + phase *= Complex64::new(0.0, 1.0); + } + } + if src_minus { + phase *= Complex64::new(-1.0, 0.0); + } + if src_i { + phase *= Complex64::new(0.0, 1.0); + } + + // Update destabs[dst_q] bits + let destabs_mut = tableau.destabs_mut(); + for q in &src_x { + destabs_mut.col_x[q].toggle(dst_q); + } + for q in &src_z { + destabs_mut.col_z[q].toggle(dst_q); + } + destabs_mut.row_x[dst_q].xor_assign(&src_x); + destabs_mut.row_z[dst_q].xor_assign(&src_z); + + apply_phase_to_sign(destabs_mut, dst_q, phase); +} + +/// Combine `phase` (expected to be a fourth root of unity) into the row's sign. +fn apply_phase_to_sign(gens: &mut GensGeneric, row: usize, phase: Complex64) { + let d_minus = gens.signs_minus.contains(row); + let d_i = gens.signs_i.contains(row); + let old_sign = match (d_minus, d_i) { + (false, false) => Complex64::new(1.0, 0.0), + (true, false) => Complex64::new(-1.0, 0.0), + (false, true) => Complex64::new(0.0, 1.0), + (true, true) => Complex64::new(0.0, -1.0), + }; + let new_sign = old_sign * phase; + let (new_minus, new_i) = if (new_sign - Complex64::new(1.0, 0.0)).norm() < 1e-9 { + (false, false) + } else if (new_sign - Complex64::new(-1.0, 0.0)).norm() < 1e-9 { + (true, false) + } else if (new_sign - Complex64::new(0.0, 1.0)).norm() < 1e-9 { + (false, true) + } else if (new_sign - Complex64::new(0.0, -1.0)).norm() < 1e-9 { + (true, true) + } else { + panic!("phase not a fourth root of unity: {new_sign}"); + }; + if new_minus != d_minus { + gens.signs_minus.toggle(row); + } + if new_i != d_i { + gens.signs_i.toggle(row); + } +} + +// Silence unused warnings +#[allow(dead_code)] +fn _type_check() -> BitSet { + BitSet::new() +} + +#[cfg(test)] +mod tests { + use super::*; + use nalgebra::DMatrix; + use pecos_core::QubitId; + use pecos_simulators::{CliffordGateable, SparseStabY}; + + /// Verify that right-composing G and then left-composing G^-1 gives identity. + /// (This doesn't fully test right-compose but is a sanity check.) + + #[test] + fn test_right_compose_h_twice_is_identity() { + // H * H = I, so right-composing H twice should leave tableau unchanged + let mut t = SparseStabY::new(3).with_destab_sign_tracking(); + t.h(&[QubitId(0)]); + t.cx(&[(QubitId(0), QubitId(1))]); + let before_stabs_x: Vec<_> = (0..3).map(|i| t.stabs().row_x[i].clone()).collect(); + let before_stabs_z: Vec<_> = (0..3).map(|i| t.stabs().row_z[i].clone()).collect(); + + right_compose_h(&mut t, 0); + right_compose_h(&mut t, 0); + + for i in 0..3 { + assert_eq!(t.stabs().row_x[i], before_stabs_x[i], "stab {i} x changed"); + assert_eq!(t.stabs().row_z[i], before_stabs_z[i], "stab {i} z changed"); + } + } + + #[test] + fn test_right_compose_h_swaps_stab_destab() { + // Initial state: stabs=[Z_0, Z_1], destabs=[X_0, X_1] + // After right-compose H_0: stabs[0] should become what destabs[0] was (X_0), + // destabs[0] should become what stabs[0] was (Z_0). + let mut t = SparseStabY::new(2); + // Initial: stab[0] = Z_0 (row_z={0}, row_x={}) + // destab[0] = X_0 (row_x={0}, row_z={}) + assert!(t.stabs().row_z[0].contains(0)); + assert!(!t.stabs().row_x[0].contains(0)); + assert!(t.destabs().row_x[0].contains(0)); + assert!(!t.destabs().row_z[0].contains(0)); + + right_compose_h(&mut t, 0); + + // After: stab[0] should be X_0, destab[0] should be Z_0 + assert!( + t.stabs().row_x[0].contains(0), + "stab[0] should have X after H" + ); + assert!(!t.stabs().row_z[0].contains(0)); + assert!( + t.destabs().row_z[0].contains(0), + "destab[0] should have Z after H" + ); + assert!(!t.destabs().row_x[0].contains(0)); + } + + /// Build the 2^n x 2^n matrix for a generator row. + fn gen_matrix( + gens: &GensGeneric, + row: usize, + n: usize, + ) -> nalgebra::DMatrix { + let i_mat = DMatrix::::identity(2, 2); + let x_mat = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let z_mat = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(-1.0, 0.0), + ], + ); + let y_mat = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(0.0, -1.0), + Complex64::new(0.0, 1.0), + Complex64::new(0.0, 0.0), + ], + ); + let mut result = DMatrix::from_element(1, 1, Complex64::new(1.0, 0.0)); + for q in 0..n { + let has_x = gens.row_x[row].contains(q); + let has_z = gens.row_z[row].contains(q); + let p = match (has_x, has_z) { + (false, false) => &i_mat, + (true, false) => &x_mat, + (false, true) => &z_mat, + (true, true) => &y_mat, + }; + result = result.kronecker(p); + } + let mut phase = Complex64::new(1.0, 0.0); + if gens.signs_minus.contains(row) { + phase *= Complex64::new(-1.0, 0.0); + } + if gens.signs_i.contains(row) { + phase *= Complex64::new(0.0, 1.0); + } + result * phase + } + + /// Verify that right-composing G transforms `S_k` into C (G `Z_k` G^dagger) C^dagger. + /// We do this by brute-force: construct gate matrix G, compute expected `S_k`, compare. + #[test] + fn test_right_compose_h_correct_transformation() { + // Start with some non-trivial state + let mut t = SparseStabY::new(2).with_destab_sign_tracking(); + t.h(&[QubitId(0)]); + t.cx(&[(QubitId(0), QubitId(1))]); + + // Compute S_0, S_1 before right-compose + let s0_before = gen_matrix(t.stabs(), 0, 2); + let s1_before = gen_matrix(t.stabs(), 1, 2); + + // Right-compose H on qubit 0 + right_compose_h(&mut t, 0); + + // After right-compose by H_0, S_k should be C (H_0 Z_k H_0) C^dagger. + // H_0 Z_0 H_0 = X_0, H_0 Z_1 H_0 = Z_1 (H only on qubit 0). + // So S_0' = C X_0 C^dagger = D_0 (original destabilizer 0) + // S_1' = C Z_1 C^dagger = S_1 (unchanged) + let s0_after = gen_matrix(t.stabs(), 0, 2); + let s1_after = gen_matrix(t.stabs(), 1, 2); + + assert!( + (s1_after.clone() - s1_before).norm() < 1e-10, + "S_1 should be unchanged" + ); + // S_0 should equal what D_0 was before (we can't easily recompute that here, + // but we can verify S_0 != original S_0) + assert!( + (s0_after.clone() - s0_before).norm() > 1e-3, + "S_0 should have changed" + ); + + // Verify stabilizer algebra: S_0' and S_1' should anticommute appropriately with + // the destabilizers (which also got transformed). + let d0_after = gen_matrix(t.destabs(), 0, 2); + let d1_after = gen_matrix(t.destabs(), 1, 2); + + // S_k and D_k should anticommute: S_k D_k + D_k S_k = 0 + let anti_00 = &s0_after * &d0_after + &d0_after * &s0_after; + let anti_11 = &s1_after * &d1_after + &d1_after * &s1_after; + assert!(anti_00.norm() < 1e-10, "S_0 and D_0 should anticommute"); + assert!(anti_11.norm() < 1e-10, "S_1 and D_1 should anticommute"); + + // S_k and D_j (k != j) should commute: S_k D_j = D_j S_k + let comm_01 = &s0_after * &d1_after - &d1_after * &s0_after; + let comm_10 = &s1_after * &d0_after - &d0_after * &s1_after; + assert!(comm_01.norm() < 1e-10, "S_0 and D_1 should commute"); + assert!(comm_10.norm() < 1e-10, "S_1 and D_0 should commute"); + + // S_0 and S_1 should commute (stabilizers all commute with each other) + let comm_ss = &s0_after * &s1_after - &s1_after * &s0_after; + assert!(comm_ss.norm() < 1e-10, "S_0 and S_1 should commute"); + } + + #[test] + fn test_right_compose_cx_preserves_algebra() { + // Right-compose CX should preserve the symplectic structure + let mut t = SparseStabY::new(3).with_destab_sign_tracking(); + t.h(&[QubitId(0)]); + t.cx(&[(QubitId(0), QubitId(1))]); + + right_compose_cx(&mut t, 0, 2); + + // Verify stabilizer/destabilizer algebra + let stabs: Vec<_> = (0..3).map(|i| gen_matrix(t.stabs(), i, 3)).collect(); + let destabs: Vec<_> = (0..3).map(|i| gen_matrix(t.destabs(), i, 3)).collect(); + + for i in 0..3 { + // S_i and D_i anticommute + let anti = &stabs[i] * &destabs[i] + &destabs[i] * &stabs[i]; + assert!(anti.norm() < 1e-10, "S_{i} and D_{i} should anticommute"); + // S_i and S_j commute (j != i) + for j in 0..3 { + if i == j { + continue; + } + let comm_ss = &stabs[i] * &stabs[j] - &stabs[j] * &stabs[i]; + assert!(comm_ss.norm() < 1e-10, "S_{i} and S_{j} should commute"); + // S_i and D_j commute + let comm_sd = &stabs[i] * &destabs[j] - &destabs[j] * &stabs[i]; + assert!(comm_sd.norm() < 1e-10, "S_{i} and D_{j} should commute"); + } + } + } + + #[test] + fn test_right_compose_sz_preserves_algebra() { + let mut t = SparseStabY::new(2).with_destab_sign_tracking(); + t.h(&[QubitId(0)]); + t.cx(&[(QubitId(0), QubitId(1))]); + + right_compose_sz(&mut t, 0); + + let stabs: Vec<_> = (0..2).map(|i| gen_matrix(t.stabs(), i, 2)).collect(); + let destabs: Vec<_> = (0..2).map(|i| gen_matrix(t.destabs(), i, 2)).collect(); + + for i in 0..2 { + let anti = &stabs[i] * &destabs[i] + &destabs[i] * &stabs[i]; + assert!( + anti.norm() < 1e-10, + "S_{i} and D_{i} should anticommute after right-compose SZ" + ); + } + } + + #[test] + fn test_right_compose_szdg_preserves_algebra() { + let mut t = SparseStabY::new(2).with_destab_sign_tracking(); + t.h(&[QubitId(0)]); + right_compose_szdg(&mut t, 0); + + let stabs: Vec<_> = (0..2).map(|i| gen_matrix(t.stabs(), i, 2)).collect(); + let destabs: Vec<_> = (0..2).map(|i| gen_matrix(t.destabs(), i, 2)).collect(); + for i in 0..2 { + let anti = &stabs[i] * &destabs[i] + &destabs[i] * &stabs[i]; + assert!(anti.norm() < 1e-10); + } + } + + #[test] + fn test_right_compose_s_then_sdg_is_identity() { + // S * Sdg = I + let mut t = SparseStabY::new(2).with_destab_sign_tracking(); + t.h(&[QubitId(0)]); + t.cx(&[(QubitId(0), QubitId(1))]); + + let before = gen_matrix(t.destabs(), 0, 2); + right_compose_sz(&mut t, 0); + right_compose_szdg(&mut t, 0); + let after = gen_matrix(t.destabs(), 0, 2); + assert!( + (after - before).norm() < 1e-10, + "S then Sdg should be identity" + ); + } + + #[test] + fn test_right_compose_x_flips_stab_sign() { + let mut t = SparseStabY::new(2); + let before_sign = t.stabs().signs_minus.contains(0); + right_compose_x(&mut t, 0); + let after_sign = t.stabs().signs_minus.contains(0); + assert_ne!(before_sign, after_sign, "X should flip stab sign"); + // Destab unchanged + assert!(!t.destabs().signs_minus.contains(0)); + } + + /// Directly test: does `right_compose_cy` implement CY or -CY? + /// Build two tableaus: one with `right_compose_cy`, one with the reference's + /// Sdg-CX-S pattern. They should be equivalent if both implement CY. + #[test] + fn test_right_compose_cy_vs_reference_pattern() { + let mut t_mine = SparseStabY::new(3).with_destab_sign_tracking(); + t_mine.h(&[QubitId(0)]); + t_mine.cx(&[(QubitId(0), QubitId(1))]); + let mut t_ref = t_mine.clone(); + + // Mine: right_compose_cy = S, CX, Sdg (in call order) + right_compose_cy(&mut t_mine, 0, 2); + + // Reference pattern: Sdg, CX, S (in call order) + right_compose_szdg(&mut t_ref, 2); + right_compose_cx(&mut t_ref, 0, 2); + right_compose_sz(&mut t_ref, 2); + + // Compare generator matrices + let m_mine: Vec<_> = (0..3).map(|i| gen_matrix(t_mine.stabs(), i, 3)).collect(); + let m_ref: Vec<_> = (0..3).map(|i| gen_matrix(t_ref.stabs(), i, 3)).collect(); + + for i in 0..3 { + let diff = (&m_mine[i] - &m_ref[i]).norm(); + let neg_diff = (&m_mine[i] + &m_ref[i]).norm(); + eprintln!("stab {i}: diff_eq={diff:.3e}, diff_neg={neg_diff:.3e}"); + } + + let d_mine: Vec<_> = (0..3).map(|i| gen_matrix(t_mine.destabs(), i, 3)).collect(); + let d_ref: Vec<_> = (0..3).map(|i| gen_matrix(t_ref.destabs(), i, 3)).collect(); + for i in 0..3 { + let diff = (&d_mine[i] - &d_ref[i]).norm(); + let neg_diff = (&d_mine[i] + &d_ref[i]).norm(); + eprintln!("destab {i}: diff_eq={diff:.3e}, diff_neg={neg_diff:.3e}"); + } + } + + #[test] + fn test_right_compose_cy_preserves_algebra() { + let mut t = SparseStabY::new(3).with_destab_sign_tracking(); + t.h(&[QubitId(0)]); + t.cx(&[(QubitId(0), QubitId(1))]); + + right_compose_cy(&mut t, 0, 2); + + let stabs: Vec<_> = (0..3).map(|i| gen_matrix(t.stabs(), i, 3)).collect(); + let destabs: Vec<_> = (0..3).map(|i| gen_matrix(t.destabs(), i, 3)).collect(); + for i in 0..3 { + let anti = &stabs[i] * &destabs[i] + &destabs[i] * &stabs[i]; + assert!(anti.norm() < 1e-10, "S_{i} and D_{i} should anticommute"); + for j in 0..3 { + if i == j { + continue; + } + let comm_ss = &stabs[i] * &stabs[j] - &stabs[j] * &stabs[i]; + assert!(comm_ss.norm() < 1e-10); + let comm_sd = &stabs[i] * &destabs[j] - &destabs[j] * &stabs[i]; + assert!(comm_sd.norm() < 1e-10); + } + } + } + + #[test] + fn test_right_compose_cx_updates_rows() { + // Right-compose CX(0, 1) on identity tableau: + // stabs[1] *= stabs[0] means stab[1] = Z_1 * Z_0 = Z_0 Z_1 + // destabs[0] *= destabs[1] means destab[0] = X_0 * X_1 = X_0 X_1 + let mut t = SparseStabY::new(3).with_destab_sign_tracking(); + right_compose_cx(&mut t, 0, 1); + + // stab[1] should now have Z on both qubit 0 and qubit 1 + assert!( + t.stabs().row_z[1].contains(0), + "stab[1] should have Z on q0" + ); + assert!( + t.stabs().row_z[1].contains(1), + "stab[1] should have Z on q1" + ); + // stab[0] unchanged + assert!(t.stabs().row_z[0].contains(0)); + assert!(!t.stabs().row_z[0].contains(1)); + // destab[0] should have X on both qubits + assert!(t.destabs().row_x[0].contains(0)); + assert!(t.destabs().row_x[0].contains(1)); + // destab[1] unchanged + assert!(t.destabs().row_x[1].contains(1)); + assert!(!t.destabs().row_x[1].contains(0)); + } +} diff --git a/exp/pecos-stab-tn/tests/verification.rs b/exp/pecos-stab-tn/tests/verification.rs new file mode 100644 index 000000000..c69e51242 --- /dev/null +++ b/exp/pecos-stab-tn/tests/verification.rs @@ -0,0 +1,3264 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Verification tests comparing STN and MAST against `StabVec`. + +use num_complex::Complex64; +use pecos_core::{Angle64, QubitId}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, QuantumSimulator, StabVec}; +use pecos_stab_tn::stab_mps::StabMps; +use pecos_stab_tn::stab_mps::mast::Mast; + +/// Check that two state vectors match up to global phase. +fn assert_states_match(sv_a: &[Complex64], sv_b: &[Complex64], label: &str) { + assert_states_close(sv_a, sv_b, 0.01, label); +} + +fn assert_states_close(sv_a: &[Complex64], sv_b: &[Complex64], tol: f64, label: &str) { + assert_eq!(sv_a.len(), sv_b.len(), "{label}: dimension mismatch"); + let norm_a: f64 = sv_a.iter().map(num_complex::Complex::norm_sqr).sum(); + let norm_b: f64 = sv_b.iter().map(num_complex::Complex::norm_sqr).sum(); + assert!( + (norm_a - 1.0).abs() < tol + 0.01, + "{label}: norm_a = {norm_a:.4}" + ); + assert!( + (norm_b - 1.0).abs() < tol + 0.01, + "{label}: norm_b = {norm_b:.4}" + ); + let overlap: Complex64 = sv_a + .iter() + .zip(sv_b.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + assert!( + (overlap.norm_sqr() - 1.0).abs() < tol, + "{label}: overlap = {:.4} (should be 1.0, tol={tol})", + overlap.norm_sqr() + ); +} + +/// Apply a random-ish Clifford+T circuit to both STN and `StabVec`. +fn run_circuit_on_both( + n: usize, + gates: &[(&str, Vec, Option)], + seed: u64, +) -> (Vec, Vec) { + let mut stn = StabMps::with_seed(n, seed); + let mut crz = StabVec::builder(n).seed(seed).build(); + + for (gate, qubits, angle) in gates { + let qids: Vec = qubits.iter().map(|&q| QubitId(q)).collect(); + match *gate { + "h" => { + stn.h(&qids); + crz.h(&qids); + } + "sz" => { + stn.sz(&qids); + crz.sz(&qids); + } + "x" => { + stn.x(&qids); + crz.x(&qids); + } + "z" => { + stn.z(&qids); + crz.z(&qids); + } + "cx" => { + let pairs = vec![(QubitId(qubits[0]), QubitId(qubits[1]))]; + stn.cx(&pairs); + crz.cx(&pairs); + } + "cz" => { + let pairs = vec![(QubitId(qubits[0]), QubitId(qubits[1]))]; + stn.cz(&pairs); + crz.cz(&pairs); + } + "rz" => { + let theta = angle.unwrap(); + stn.rz(theta, &qids); + crz.rz(theta, &qids); + } + "rx" => { + let theta = angle.unwrap(); + stn.rx(theta, &qids); + crz.rx(theta, &qids); + } + "rzz" => { + let theta = angle.unwrap(); + let pairs = vec![(QubitId(qubits[0]), QubitId(qubits[1]))]; + stn.rzz(theta, &pairs); + crz.rzz(theta, &pairs); + } + "t" => { + let t = Angle64::QUARTER_TURN / 2u64; + stn.rz(t, &qids); + crz.rz(t, &qids); + } + _ => panic!("unknown gate: {gate}"), + } + } + + (stn.state_vector(), crz.state_vector()) +} + +// ============================================================================ +// State vector cross-validation tests +// ============================================================================ + +#[test] +fn test_4qubit_random_circuit() { + let gates = vec![ + ("h", vec![0], None), + ("cx", vec![0, 1], None), + ("h", vec![2], None), + ("cx", vec![2, 3], None), + ("t", vec![0], None), + ("t", vec![2], None), + ("cx", vec![1, 2], None), + ("t", vec![1], None), + ("h", vec![3], None), + ("rz", vec![3], Some(Angle64::from_radians(0.7))), + ]; + let (stn_sv, crz_sv) = run_circuit_on_both(4, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "4-qubit random circuit"); +} + +#[test] +fn test_5qubit_deep_circuit() { + let gates = vec![ + ("h", vec![0], None), + ("h", vec![1], None), + ("h", vec![2], None), + ("cx", vec![0, 1], None), + ("cx", vec![2, 3], None), + ("cx", vec![3, 4], None), + ("t", vec![0], None), + ("t", vec![1], None), + ("t", vec![2], None), + ("cx", vec![1, 2], None), + ("h", vec![0], None), + ("t", vec![0], None), + ("cz", vec![0, 3], None), + ("rz", vec![4], Some(Angle64::from_radians(1.5))), + ("cx", vec![4, 0], None), + ("t", vec![4], None), + ]; + let (stn_sv, crz_sv) = run_circuit_on_both(5, &gates, 123); + assert_states_match(&stn_sv, &crz_sv, "5-qubit deep circuit"); +} + +#[test] +fn test_repeated_t_on_same_qubit() { + // T^8 = I (up to phase). 8 T gates on the same qubit. + let mut gates = vec![("h", vec![0], None)]; + for _ in 0..8 { + gates.push(("t", vec![0], None)); + } + let (stn_sv, crz_sv) = run_circuit_on_both(1, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "T^8 on |+>"); +} + +#[test] +fn test_rx_gate() { + let theta = Angle64::from_radians(std::f64::consts::FRAC_PI_3); + let gates = vec![ + ("rx", vec![0], Some(theta)), + ("cx", vec![0, 1], None), + ("rx", vec![1], Some(theta)), + ]; + let (stn_sv, crz_sv) = run_circuit_on_both(2, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "RX circuits"); +} + +#[test] +fn test_rzz_gate() { + let theta = Angle64::from_radians(0.5); + let gates = vec![ + ("h", vec![0], None), + ("h", vec![1], None), + ("rzz", vec![0, 1], Some(theta)), + ]; + let (stn_sv, crz_sv) = run_circuit_on_both(2, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "RZZ gate"); +} + +#[test] +fn test_alternating_clifford_and_t() { + // H, T, S, T, H, T, S, T on 2 qubits with entangling + let gates = vec![ + ("h", vec![0], None), + ("t", vec![0], None), + ("sz", vec![0], None), + ("cx", vec![0, 1], None), + ("t", vec![1], None), + ("h", vec![1], None), + ("t", vec![1], None), + ("sz", vec![1], None), + ("cx", vec![1, 0], None), + ("t", vec![0], None), + ]; + let (stn_sv, crz_sv) = run_circuit_on_both(2, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "alternating Clifford+T"); +} + +// ============================================================================ +// Measurement probability tests +// ============================================================================ + +#[test] +fn test_rx_measurement_probabilities() { + // RX(pi/3)|0> has prob(0) = cos^2(pi/6) = 3/4 + let expected_p0 = 0.75; + let theta = Angle64::from_radians(std::f64::consts::FRAC_PI_3); + + let num_trials = 1000; + let mut count_0 = 0; + for trial in 0..num_trials { + let mut stn = StabMps::with_seed(1, 10_000 + trial); + stn.rx(theta, &[QubitId(0)]); + if !stn.mz(&[QubitId(0)])[0].outcome { + count_0 += 1; + } + } + let p0 = f64::from(count_0) / num_trials as f64; + assert!( + (p0 - expected_p0).abs() < 0.05, + "p(0) = {p0:.3}, expected {expected_p0:.3}" + ); +} + +#[test] +fn test_ghz_measurement_correlation() { + // GHZ state: H, CX chain, T on first qubit. + // All qubits should be correlated. + let n = 4; + let num_trials = 100; + let mut all_correlated = 0; + + for trial in 0..num_trials { + let mut stn = StabMps::with_seed(n, 20_000 + trial); + stn.h(&[QubitId(0)]); + for q in 0..(n - 1) { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + // Apply T to make it non-trivial + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + + let results: Vec = (0..n).map(|q| stn.mz(&[QubitId(q)])[0].outcome).collect(); + + if results.iter().all(|&r| r == results[0]) { + all_correlated += 1; + } + } + let rate = f64::from(all_correlated) / num_trials as f64; + assert!( + rate > 0.90, + "GHZ+T correlation rate {rate:.2} should be > 0.90" + ); +} + +// ============================================================================ +// MAST vs STN comparison +// ============================================================================ + +#[test] +fn test_mast_vs_stn_measurement_statistics() { + // Compare measurement outcome distributions between MAST and STN. + let num_trials = 500; + let mut stn_outcomes = [0u32; 4]; // 2 qubits -> 4 outcomes + let mut mast_outcomes = [0u32; 4]; + + for trial in 0..num_trials { + // STN version + let mut stn = StabMps::with_seed(2, 30_000 + trial); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let r0 = stn.mz(&[QubitId(0)])[0].outcome; + let r1 = stn.mz(&[QubitId(1)])[0].outcome; + let idx = (usize::from(r0) << 1) | usize::from(r1); + stn_outcomes[idx] += 1; + + // MAST version + let mut mast = Mast::with_seed(2, 4, 30_000 + trial); + mast.h(&[QubitId(0)]); + mast.cx(&[(QubitId(0), QubitId(1))]); + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let r0 = mast.mz(&[QubitId(0)])[0].outcome; + let r1 = mast.mz(&[QubitId(1)])[0].outcome; + let idx = (usize::from(r0) << 1) | usize::from(r1); + mast_outcomes[idx] += 1; + } + + // Bell+T: only |00> and |11> should appear (correlation preserved) + let stn_p00 = f64::from(stn_outcomes[0]) / num_trials as f64; + let stn_p11 = f64::from(stn_outcomes[3]) / num_trials as f64; + let mast_p00 = f64::from(mast_outcomes[0]) / num_trials as f64; + let mast_p11 = f64::from(mast_outcomes[3]) / num_trials as f64; + + // Both should have ~50% |00> and ~50% |11> + assert!((stn_p00 - 0.5).abs() < 0.1, "STN p(00) = {stn_p00:.2}"); + assert!((stn_p11 - 0.5).abs() < 0.1, "STN p(11) = {stn_p11:.2}"); + assert!((mast_p00 - 0.5).abs() < 0.1, "MAST p(00) = {mast_p00:.2}"); + assert!((mast_p11 - 0.5).abs() < 0.1, "MAST p(11) = {mast_p11:.2}"); + + // Both should have no |01> or |10> (perfect correlation) + assert!( + stn_outcomes[1] + stn_outcomes[2] == 0, + "STN has uncorrelated outcomes: {stn_outcomes:?}" + ); + assert!( + mast_outcomes[1] + mast_outcomes[2] == 0, + "MAST has uncorrelated outcomes: {mast_outcomes:?}" + ); +} + +// ============================================================================ +// Compression / bond dimension tests +// ============================================================================ + +#[test] +fn test_bond_dim_growth_with_t_gates() { + // Track bond dimension as T gates accumulate + let mut stn = StabMps::new(6); + for q in 0..6 { + stn.h(&[QubitId(q)]); + } + for q in 0..5 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + + let mut bond_dims = vec![stn.max_bond_dim()]; + for q in 0..6 { + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(q)]); + bond_dims.push(stn.max_bond_dim()); + } + + // Bond dimension should grow but stay reasonable with compression + assert!( + *bond_dims.last().unwrap() < 64, + "bond dim after 6 T gates: {bond_dims:?}" + ); +} + +// ============================================================================ +// Randomized fuzz testing +// ============================================================================ + +/// Generate a pseudo-random circuit and compare STN vs `DenseStateVec` state vectors. +fn fuzz_circuit(num_qubits: usize, num_gates: usize, seed: u64) { + // Tolerance scales with circuit depth: more SVD ops → more numerical drift + let tol = 0.01 + 0.002 * num_gates as f64; + fuzz_circuit_with_tol(num_qubits, num_gates, seed, tol); +} + +fn fuzz_circuit_with_tol(num_qubits: usize, num_gates: usize, seed: u64, tol: f64) { + let mut stn = StabMps::with_seed(num_qubits, seed); + // Use DenseStateVec as reference (not CRZ, which has frame optimization issues with CZ) + let mut crz = pecos_simulators::DenseStateVec::new(num_qubits); + + // Use seed to generate a deterministic sequence of gates + let mut rng_state = seed; + let next_rng = |state: &mut u64| -> u64 { + // Simple xorshift + *state ^= *state << 13; + *state ^= *state >> 7; + *state ^= *state << 17; + *state + }; + + for _ in 0..num_gates { + let gate_type = next_rng(&mut rng_state) % 8; + let q0 = (next_rng(&mut rng_state) % num_qubits as u64) as usize; + let q1 = loop { + let q = (next_rng(&mut rng_state) % num_qubits as u64) as usize; + if q != q0 { + break q; + } + }; + + match gate_type { + 0 => { + stn.h(&[QubitId(q0)]); + crz.h(&[QubitId(q0)]); + } + 1 => { + stn.sz(&[QubitId(q0)]); + crz.sz(&[QubitId(q0)]); + } + 2 => { + stn.x(&[QubitId(q0)]); + crz.x(&[QubitId(q0)]); + } + 3 => { + stn.cx(&[(QubitId(q0), QubitId(q1))]); + crz.cx(&[(QubitId(q0), QubitId(q1))]); + } + 4 => { + stn.cz(&[(QubitId(q0), QubitId(q1))]); + crz.cz(&[(QubitId(q0), QubitId(q1))]); + } + 5 => { + // T gate + let t = Angle64::QUARTER_TURN / 2u64; + stn.rz(t, &[QubitId(q0)]); + crz.rz(t, &[QubitId(q0)]); + } + 6 => { + // Random RZ angle + let angle_bits = next_rng(&mut rng_state); + let angle = Angle64::from_radians( + (angle_bits % 1000) as f64 * 0.001 * std::f64::consts::TAU, + ); + stn.rz(angle, &[QubitId(q0)]); + crz.rz(angle, &[QubitId(q0)]); + } + _ => { + // RX + let angle_bits = next_rng(&mut rng_state); + let angle = Angle64::from_radians( + (angle_bits % 1000) as f64 * 0.001 * std::f64::consts::TAU, + ); + stn.rx(angle, &[QubitId(q0)]); + crz.rx(angle, &[QubitId(q0)]); + } + } + } + + let stn_sv = stn.state_vector(); + let dim = 1usize << num_qubits; + let ref_sv: Vec = (0..dim).map(|i| crz.get_amplitude(i)).collect(); + + let overlap: Complex64 = stn_sv + .iter() + .zip(ref_sv.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + if (overlap.norm_sqr() - 1.0).abs() > tol { + // Re-run step-by-step to find the divergence point + let mut stn2 = StabMps::with_seed(num_qubits, seed); + let mut dsv2 = pecos_simulators::DenseStateVec::new(num_qubits); + let mut rng2 = seed; + let next2 = |state: &mut u64| -> u64 { + *state ^= *state << 13; + *state ^= *state >> 7; + *state ^= *state << 17; + *state + }; + for step in 0..num_gates { + let gt = next2(&mut rng2) % 8; + let q0s = (next2(&mut rng2) % num_qubits as u64) as usize; + let q1s = loop { + let q = (next2(&mut rng2) % num_qubits as u64) as usize; + if q != q0s { + break q; + } + }; + let names = ["h", "sz", "x", "cx", "cz", "t", "rz", "rx"]; + match gt { + 0 => { + stn2.h(&[QubitId(q0s)]); + dsv2.h(&[QubitId(q0s)]); + } + 1 => { + stn2.sz(&[QubitId(q0s)]); + dsv2.sz(&[QubitId(q0s)]); + } + 2 => { + stn2.x(&[QubitId(q0s)]); + dsv2.x(&[QubitId(q0s)]); + } + 3 => { + stn2.cx(&[(QubitId(q0s), QubitId(q1s))]); + dsv2.cx(&[(QubitId(q0s), QubitId(q1s))]); + } + 4 => { + stn2.cz(&[(QubitId(q0s), QubitId(q1s))]); + dsv2.cz(&[(QubitId(q0s), QubitId(q1s))]); + } + 5 => { + let t = Angle64::QUARTER_TURN / 2u64; + stn2.rz(t, &[QubitId(q0s)]); + dsv2.rz(t, &[QubitId(q0s)]); + } + 6 => { + let ab = next2(&mut rng2); + let a = + Angle64::from_radians((ab % 1000) as f64 * 0.001 * std::f64::consts::TAU); + stn2.rz(a, &[QubitId(q0s)]); + dsv2.rz(a, &[QubitId(q0s)]); + } + _ => { + let ab = next2(&mut rng2); + let a = + Angle64::from_radians((ab % 1000) as f64 * 0.001 * std::f64::consts::TAU); + stn2.rx(a, &[QubitId(q0s)]); + dsv2.rx(a, &[QubitId(q0s)]); + } + } + let sv2 = stn2.state_vector(); + let rv2: Vec = (0..dim).map(|i| dsv2.get_amplitude(i)).collect(); + let ov: Complex64 = sv2.iter().zip(rv2.iter()).map(|(a, b)| a.conj() * b).sum(); + if (ov.norm_sqr() - 1.0).abs() > tol { + eprintln!( + "seed={seed}: diverged at step {step} ({}(q{q0s})): overlap={:.4}, bonds={:?}, mps_norm={:.4}", + names[gt as usize], + ov.norm_sqr(), + stn2.mps().bond_dims(), + stn2.mps().norm_squared() + ); + eprintln!( + " STN: {:?}", + sv2.iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + eprintln!( + " REF: {:?}", + rv2.iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + break; + } + } + } + + assert_states_close( + &stn_sv, + &ref_sv, + tol, + &format!("fuzz n={num_qubits} gates={num_gates} seed={seed}"), + ); +} + +#[test] +fn test_fuzz_2qubit_circuits() { + for seed in 100..200 { + fuzz_circuit(2, 10, seed); + } +} + +#[test] +fn test_fuzz_seed_115_mps_check() { + let q0 = QubitId(0); + let q1 = QubitId(1); + let mut stn = StabMps::with_seed(2, 115); + stn.cx(&[(q0, q1)]); + stn.cz(&[(q0, q1)]); + stn.cx(&[(q1, q0)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[q1]); + let mps3 = stn.mps().state_vector(); + eprintln!( + "Step 3 MPS: {:?}", + mps3.iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + + stn.cz(&[(q0, q1)]); + stn.h(&[q0]); + stn.cz(&[(q0, q1)]); + stn.sz(&[q0]); + stn.rz(Angle64::from_radians(0.2702), &[q1]); + let mps8 = stn.mps().state_vector(); + eprintln!( + "Step 8 MPS: {:?}", + mps8.iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + // Reference: [0.8639-0.5036i, 0, 0, 0] + approx::assert_relative_eq!(mps8[0].re, 0.8639, epsilon = 0.01); + approx::assert_relative_eq!(mps8[0].im, -0.5036, epsilon = 0.01); + + // Compare state_vector vs DenseStateVec + stn.cx(&[(q0, q1)]); // Step 9 + let stn_sv = stn.state_vector(); + let mut dsv = pecos_simulators::DenseStateVec::new(2); + dsv.cx(&[(q0, q1)]); + dsv.cz(&[(q0, q1)]); + dsv.cx(&[(q1, q0)]); + dsv.rz(Angle64::QUARTER_TURN / 2u64, &[q1]); + dsv.cz(&[(q0, q1)]); + dsv.h(&[q0]); + dsv.cz(&[(q0, q1)]); + dsv.sz(&[q0]); + dsv.rz(Angle64::from_radians(0.2702), &[q1]); + dsv.cx(&[(q0, q1)]); + let ref_sv: Vec = (0..4).map(|i| dsv.get_amplitude(i)).collect(); + eprintln!( + "STN SV: {:?}", + stn_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + eprintln!( + "DSV SV: {:?}", + ref_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + let overlap: Complex64 = stn_sv + .iter() + .zip(ref_sv.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + eprintln!("Overlap: {:.4}", overlap.norm_sqr()); +} + +#[test] +fn test_fuzz_seed_101_measurement_stats() { + // Verify STN measurement probabilities match the state vector. + let t = Angle64::QUARTER_TURN / 2u64; + let rz_angle = Angle64::from_radians(4.0024); + let rx1 = Angle64::from_radians(5.6800); + let rx2 = Angle64::from_radians(5.3973); + + // Compute expected probabilities from state vector. + let mut stn_ref = StabMps::with_seed(2, 42); + stn_ref.rz(t, &[QubitId(1)]); + stn_ref.h(&[QubitId(0)]); + stn_ref.sz(&[QubitId(1)]); + stn_ref.sz(&[QubitId(0)]); + stn_ref.rz(rz_angle, &[QubitId(0)]); + stn_ref.rx(rx1, &[QubitId(0)]); + stn_ref.rx(rx2, &[QubitId(1)]); + stn_ref.x(&[QubitId(0)]); + stn_ref.x(&[QubitId(0)]); + stn_ref.rz(t, &[QubitId(0)]); + let sv = stn_ref.state_vector(); + // sv[i] uses DenseStateVec convention: bit 0 = q0, bit 1 = q1 + let expected_probs: Vec = sv.iter().map(num_complex::Complex::norm_sqr).collect(); + + // Sample measurements and compare. + let num_trials = 500; + let mut stn_outcomes = [0u32; 4]; + for trial in 0..num_trials { + let seed = 50_000 + trial; + let mut stn = StabMps::with_seed(2, seed); + stn.rz(t, &[QubitId(1)]); + stn.h(&[QubitId(0)]); + stn.sz(&[QubitId(1)]); + stn.sz(&[QubitId(0)]); + stn.rz(rz_angle, &[QubitId(0)]); + stn.rx(rx1, &[QubitId(0)]); + stn.rx(rx2, &[QubitId(1)]); + stn.x(&[QubitId(0)]); + stn.x(&[QubitId(0)]); + stn.rz(t, &[QubitId(0)]); + let s0 = stn.mz(&[QubitId(0)])[0].outcome; + let s1 = stn.mz(&[QubitId(1)])[0].outcome; + // Index: bit 0 = q0, bit 1 = q1 (matching DenseStateVec convention) + stn_outcomes[usize::from(s0) | (usize::from(s1) << 1)] += 1; + } + + for i in 0..4 { + let p_s = f64::from(stn_outcomes[i]) / num_trials as f64; + assert!( + (p_s - expected_probs[i]).abs() < 0.1, + "outcome {i}: STN p={p_s:.3} vs expected p={:.3}", + expected_probs[i] + ); + } +} + +#[test] +fn test_fuzz_debug_seed_101() { + // Minimal repro: T, H, S, S, RZ, RX sequence on 2 qubits + // Step-by-step comparison to find divergence point. + let t = Angle64::QUARTER_TURN / 2u64; + let rz_angle = Angle64::from_radians(4.0024); + let rx_angle1 = Angle64::from_radians(5.6800); + + let mut stn = StabMps::with_seed(2, 101); + let mut crz = StabVec::builder(2).seed(101).build(); + + // Step 0: T on q1 + stn.rz(t, &[QubitId(1)]); + crz.rz(t, &[QubitId(1)]); + + let s1 = stn.state_vector(); + let c1 = crz.state_vector(); + assert_states_match(&s1, &c1, "after T(1)"); + + // Step 1: H on q0 + stn.h(&[QubitId(0)]); + crz.h(&[QubitId(0)]); + let s2 = stn.state_vector(); + let c2 = crz.state_vector(); + assert_states_match(&s2, &c2, "after H(0)"); + + // Step 2: S on q1 + stn.sz(&[QubitId(1)]); + crz.sz(&[QubitId(1)]); + let s3 = stn.state_vector(); + let c3 = crz.state_vector(); + assert_states_match(&s3, &c3, "after S(1)"); + + // Step 3: S on q0 + stn.sz(&[QubitId(0)]); + crz.sz(&[QubitId(0)]); + let s4 = stn.state_vector(); + let c4 = crz.state_vector(); + assert_states_match(&s4, &c4, "after S(0)"); + + // Step 4: RZ on q0 + stn.rz(rz_angle, &[QubitId(0)]); + crz.rz(rz_angle, &[QubitId(0)]); + eprintln!( + "after RZ(0): MPS norm={:.6}, bonds={:?}", + stn.mps().norm_squared(), + stn.mps().bond_dims() + ); + let s5 = stn.state_vector(); + let c5 = crz.state_vector(); + assert_states_match(&s5, &c5, "after RZ(0)"); + + // Step 5: RX on q0 = H + RZ + H + // Do manually to find where norm goes wrong + stn.h(&[QubitId(0)]); + crz.h(&[QubitId(0)]); + eprintln!( + "after H(0): MPS norm={:.6}, bonds={:?}", + stn.mps().norm_squared(), + stn.mps().bond_dims() + ); + let s5h = stn.state_vector(); + let c5h = crz.state_vector(); + assert_states_match(&s5h, &c5h, "after RZ then H"); + + // Check Z_0 decomposition before inner RZ + let decomp = pecos_stab_tn::stab_mps::pauli_decomp::decompose_z( + stn.tableau().stabs(), + stn.tableau().destabs(), + 0, + ); + eprintln!("Z_0 decomp before inner RZ: {decomp:?}"); + + stn.rz(rx_angle1, &[QubitId(0)]); + crz.rz(rx_angle1, &[QubitId(0)]); + eprintln!( + "after inner RZ: MPS norm={:.6}, bonds={:?}", + stn.mps().norm_squared(), + stn.mps().bond_dims() + ); + // Check MPS SV directly against reference + let mps5 = stn.mps().state_vector(); + eprintln!( + "Step5 MPS: {:?}", + mps5.iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + eprintln!("Step5 ref: [0.4714+0.0969i, 0, 0.2176+0.8492i, 0]"); + let s5r = stn.state_vector(); + let c5r = crz.state_vector(); + assert_states_match(&s5r, &c5r, "after step 5"); + + // Continue with remaining gates from fuzz sequence + // Step 6: RX on q1 = H(1) + RZ(1) + H(1) + let rx_angle2 = Angle64::from_radians(5.3973); + stn.h(&[QubitId(1)]); + crz.h(&[QubitId(1)]); + eprintln!("step 6a (H1): norm={:.6}", stn.mps().norm_squared()); + assert_states_match(&stn.state_vector(), &crz.state_vector(), "step 6a"); + + stn.rz(rx_angle2, &[QubitId(1)]); + crz.rz(rx_angle2, &[QubitId(1)]); + eprintln!( + "step 6b (RZ1): norm={:.6}, bonds={:?}", + stn.mps().norm_squared(), + stn.mps().bond_dims() + ); + // Compare MPS with reference + let mps_sv = stn.mps().state_vector(); + eprintln!( + " Rust MPS: {:?}", + mps_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + // Reference: [0.4259+0.0876i, 0.202+0.0415i, 0.1966+0.7672i, 0.0933+0.3639i] + eprintln!(" Ref MPS: [0.4259+0.0876i, 0.2020+0.0415i, 0.1966+0.7672i, 0.0933+0.3639i]"); + // Check MPS directly vs through state_vector + let mps_sv = stn.mps().state_vector(); + let stn_sv = stn.state_vector(); + let crz_sv = crz.state_vector(); + eprintln!( + "MPS SV: {:?}", + mps_sv + .iter() + .map(|a| format!("{:.3}+{:.3}i", a.re, a.im)) + .collect::>() + ); + eprintln!( + "STN SV: {:?}", + stn_sv + .iter() + .map(|a| format!("{:.3}+{:.3}i", a.re, a.im)) + .collect::>() + ); + eprintln!( + "CRZ SV: {:?}", + crz_sv + .iter() + .map(|a| format!("{:.3}+{:.3}i", a.re, a.im)) + .collect::>() + ); + assert_states_match(&stn_sv, &crz_sv, "step 6b"); + + stn.h(&[QubitId(1)]); + crz.h(&[QubitId(1)]); + eprintln!("step 6c (H1): norm={:.6}", stn.mps().norm_squared()); + let s6 = stn.state_vector(); + let c6 = crz.state_vector(); + assert_states_match(&s6, &c6, "step 6c"); + + // Step 7: X on q0 + stn.x(&[QubitId(0)]); + crz.x(&[QubitId(0)]); + let s7 = stn.state_vector(); + let c7 = crz.state_vector(); + assert_states_match(&s7, &c7, "after step 7"); + + // Step 8: X on q0 + stn.x(&[QubitId(0)]); + crz.x(&[QubitId(0)]); + let s8 = stn.state_vector(); + let c8 = crz.state_vector(); + assert_states_match(&s8, &c8, "after step 8"); + + // Step 9: T on q0 + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + crz.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let s9 = stn.state_vector(); + let c9 = crz.state_vector(); + assert_states_match(&s9, &c9, "after step 9"); +} + +#[test] +fn test_debug_seed_502() { + let num_qubits = 2usize; + let num_gates = 30usize; + let seed = 502u64; + let dim = 1usize << num_qubits; + + let mut stn = StabMps::with_seed(num_qubits, seed); + let mut dsv = pecos_simulators::DenseStateVec::new(num_qubits); + + let mut rng_state = seed; + let next_rng = |state: &mut u64| -> u64 { + *state ^= *state << 13; + *state ^= *state >> 7; + *state ^= *state << 17; + *state + }; + + for step in 0..num_gates { + let gate_type = next_rng(&mut rng_state) % 8; + let q0 = (next_rng(&mut rng_state) % num_qubits as u64) as usize; + let q1 = loop { + let q = (next_rng(&mut rng_state) % num_qubits as u64) as usize; + if q != q0 { + break q; + } + }; + + let gate_name; + match gate_type { + 0 => { + gate_name = format!("H({q0})"); + stn.h(&[QubitId(q0)]); + dsv.h(&[QubitId(q0)]); + } + 1 => { + gate_name = format!("SZ({q0})"); + stn.sz(&[QubitId(q0)]); + dsv.sz(&[QubitId(q0)]); + } + 2 => { + gate_name = format!("X({q0})"); + stn.x(&[QubitId(q0)]); + dsv.x(&[QubitId(q0)]); + } + 3 => { + gate_name = format!("CX({q0},{q1})"); + stn.cx(&[(QubitId(q0), QubitId(q1))]); + dsv.cx(&[(QubitId(q0), QubitId(q1))]); + } + 4 => { + gate_name = format!("CZ({q0},{q1})"); + stn.cz(&[(QubitId(q0), QubitId(q1))]); + dsv.cz(&[(QubitId(q0), QubitId(q1))]); + } + 5 => { + let t = Angle64::QUARTER_TURN / 2u64; + gate_name = format!("T({q0})"); + stn.rz(t, &[QubitId(q0)]); + dsv.rz(t, &[QubitId(q0)]); + } + 6 => { + let angle_bits = next_rng(&mut rng_state); + let angle = Angle64::from_radians( + (angle_bits % 1000) as f64 * 0.001 * std::f64::consts::TAU, + ); + gate_name = format!("RZ({}, {:.4})", q0, angle.to_radians()); + stn.rz(angle, &[QubitId(q0)]); + dsv.rz(angle, &[QubitId(q0)]); + } + _ => { + let angle_bits = next_rng(&mut rng_state); + let angle = Angle64::from_radians( + (angle_bits % 1000) as f64 * 0.001 * std::f64::consts::TAU, + ); + gate_name = format!("RX({}, {:.4})", q0, angle.to_radians()); + stn.rx(angle, &[QubitId(q0)]); + dsv.rx(angle, &[QubitId(q0)]); + } + } + + let stn_sv = stn.state_vector(); + let ref_sv: Vec = (0..dim).map(|i| dsv.get_amplitude(i)).collect(); + let overlap: Complex64 = stn_sv + .iter() + .zip(ref_sv.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + let ov = overlap.norm_sqr(); + let mps_norm = stn.mps().norm_squared(); + let bonds = stn.mps().bond_dims().to_vec(); + + if (ov - 1.0).abs() > 0.01 { + eprintln!("=== DIVERGENCE at step {step}: {gate_name} ==="); + eprintln!(" overlap={ov:.6}, mps_norm={mps_norm:.6}, bonds={bonds:?}"); + eprintln!( + " STN: {:?}", + stn_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + eprintln!( + " REF: {:?}", + ref_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + panic!( + "Divergence at step {step} ({gate_name}): overlap={ov:.6}, mps_norm={mps_norm:.6}, bonds={bonds:?}" + ); + } + + eprintln!( + "step {step:2}: {gate_name:16} overlap={ov:.6} mps_norm={mps_norm:.6} bonds={bonds:?}" + ); + } +} + +#[test] +fn test_fuzz_3qubit_circuits() { + for seed in 200..300 { + fuzz_circuit(3, 12, seed); + } +} + +#[test] +fn test_fuzz_4qubit_circuits() { + for seed in 300..400 { + fuzz_circuit(4, 15, seed); + } +} + +#[test] +fn test_fuzz_5qubit() { + for seed in 400..450 { + fuzz_circuit(5, 12, seed); + } +} + +#[test] +fn test_fuzz_2qubit_deep() { + for seed in 500..600 { + fuzz_circuit(2, 30, seed); + } +} + +#[test] +fn test_rx_pi_after_nonclifford() { + // RX(pi) = -i*X. Check it works after non-Clifford gates. + let mut stn = StabMps::with_seed(2, 42); + let mut dsv = pecos_simulators::DenseStateVec::new(2); + let t = Angle64::QUARTER_TURN / 2u64; + let pi = Angle64::from_radians(std::f64::consts::PI); + + for (gate, qids, angle) in [ + ("h", vec![QubitId(0)], None), + ("h", vec![QubitId(1)], None), + ("t", vec![QubitId(0)], Some(t)), + ("cx_", vec![QubitId(0), QubitId(1)], None), + ("t", vec![QubitId(1)], Some(t)), + ("rx", vec![QubitId(0)], Some(pi)), + ] { + match gate { + "h" => { + stn.h(&qids); + dsv.h(&qids); + } + "t" => { + let a = angle.unwrap(); + stn.rz(a, &qids); + dsv.rz(a, &qids); + } + "cx_" => { + let p = vec![(qids[0], qids[1])]; + stn.cx(&p); + dsv.cx(&p); + } + "rx" => { + let a = angle.unwrap(); + stn.rx(a, &qids); + dsv.rx(a, &qids); + } + _ => {} + } + } + let stn_sv = stn.state_vector(); + let dsv_sv: Vec = (0..4).map(|i| dsv.get_amplitude(i)).collect(); + eprintln!( + "STN: {:?}", + stn_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + eprintln!( + "DSV: {:?}", + dsv_sv + .iter() + .map(|a| format!("{:.4}+{:.4}i", a.re, a.im)) + .collect::>() + ); + // Print destab signs and tracking flag + eprintln!( + " tracks_destab_signs: {}", + stn.tableau().tracks_destab_signs() + ); + for i in 0..2 { + let dm = stn.tableau().destabs().signs_minus.contains(i); + let di = stn.tableau().destabs().signs_i.contains(i); + eprintln!(" D[{i}] minus={dm} i={di}"); + } + // Also check state before RX(pi) + let mut stn2 = StabMps::with_seed(2, 42); + let mut dsv2 = pecos_simulators::DenseStateVec::new(2); + stn2.h(&[QubitId(0)]); + dsv2.h(&[QubitId(0)]); + stn2.h(&[QubitId(1)]); + dsv2.h(&[QubitId(1)]); + stn2.rz(t, &[QubitId(0)]); + dsv2.rz(t, &[QubitId(0)]); + stn2.cx(&[(QubitId(0), QubitId(1))]); + dsv2.cx(&[(QubitId(0), QubitId(1))]); + stn2.rz(t, &[QubitId(1)]); + dsv2.rz(t, &[QubitId(1)]); + let sv_before = stn2.state_vector(); + let dv_before: Vec = (0..4).map(|i| dsv2.get_amplitude(i)).collect(); + let ov_before: Complex64 = sv_before + .iter() + .zip(dv_before.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + eprintln!("Before RX(pi): overlap={:.6}", ov_before.norm_sqr()); + assert_states_match(&stn_sv, &dsv_sv, "RX(pi) after non-Clifford"); +} + +#[test] +fn test_seed319_minimal() { + // Minimal circuit from seed 319: non-Clifford, entangling, then RX(pi) + let t = Angle64::QUARTER_TURN / 2u64; + let gates = vec![ + ("t", vec![0], None), + ("h", vec![1], None), + ("rz", vec![3], Some(Angle64::from_radians(3.3427))), + ("cz", vec![0, 3], None), + ("rz", vec![1], Some(t)), // T gate = RZ(pi/4) + ("cz", vec![1, 2], None), + ("sz", vec![1], None), + ("h", vec![2], None), + ("t", vec![2], None), + ("h", vec![2], None), + ("rz", vec![3], Some(Angle64::from_radians(3.0976))), + ("rx", vec![0], Some(Angle64::from_radians(5.2025))), + ( + "rx", + vec![1], + Some(Angle64::from_radians(std::f64::consts::PI)), + ), + ]; + let (stn_sv, crz_sv) = run_circuit_on_both(4, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "seed319 minimal"); +} + +#[test] +fn test_swap_then_t() { + // Minimal reproduction: H on both, SWAP, then T on q1. + let gates = vec![ + ("h", vec![0], None), + ("h", vec![1], None), + ("cx", vec![0, 1], None), + ("cx", vec![1, 0], None), + ("cx", vec![0, 1], None), + ("t", vec![1], None), + ]; + let (stn_sv, crz_sv) = run_circuit_on_both(2, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "SWAP then T"); +} + +#[test] +fn test_h_swap_rz_t() { + // Matches the seed 502 circuit prefix up to the failing step. + let gates = vec![ + ("h", vec![0], None), + ("h", vec![1], None), + ("cx", vec![0, 1], None), + ("cx", vec![1, 0], None), + ("cx", vec![0, 1], None), + ("rx", vec![1], Some(Angle64::from_radians(5.0265))), + ("t", vec![1], None), + ]; + let (stn_sv, crz_sv) = run_circuit_on_both(2, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "H SWAP RX T"); +} + +#[test] +fn test_seed502_prefix() { + // Seed 502 circuit prefix: T(1), RZ(0), X(0), T(1), X(0), RZ(0,~pi), + // H(0), H(1), CX CX CX, RX(1), T(1) + let rz_angle = Angle64::from_radians(3.6317); // angle from seed 502 RNG + let rx_angle = Angle64::from_radians(5.0265); + // Try: full prefix T, RZ, X, T, X, Z, H, H, SWAP, RX, T + let gates = vec![ + ("t", vec![1], None), + ("rz", vec![0], Some(rz_angle)), + ("x", vec![0], None), + ("t", vec![1], None), + ("x", vec![0], None), + ( + "rz", + vec![0], + Some(Angle64::from_radians(std::f64::consts::PI)), + ), + ("h", vec![0], None), + ("h", vec![1], None), + ("cx", vec![0, 1], None), + ("cx", vec![1, 0], None), + ("cx", vec![0, 1], None), + ("rx", vec![1], Some(rx_angle)), + ("t", vec![1], None), + ]; + let mut stn = StabMps::with_seed(2, 42); + let mut dsv = pecos_simulators::DenseStateVec::new(2); + let dim = 1usize << 2; + for (step, (gate, qubits, angle)) in gates.iter().enumerate() { + let qids: Vec = qubits.iter().map(|&q| QubitId(q)).collect(); + match *gate { + "h" => { + stn.h(&qids); + dsv.h(&qids); + } + "sz" => { + stn.sz(&qids); + dsv.sz(&qids); + } + "x" => { + stn.x(&qids); + dsv.x(&qids); + } + "z" => { + stn.z(&qids); + dsv.z(&qids); + } + "cx" => { + let p = vec![(QubitId(qubits[0]), QubitId(qubits[1]))]; + stn.cx(&p); + dsv.cx(&p); + } + "rz" => { + let a = angle.unwrap(); + stn.rz(a, &qids); + dsv.rz(a, &qids); + } + "rx" => { + let a = angle.unwrap(); + stn.rx(a, &qids); + dsv.rx(a, &qids); + } + "t" => { + let t = Angle64::QUARTER_TURN / 2u64; + stn.rz(t, &qids); + dsv.rz(t, &qids); + } + _ => panic!("unknown gate"), + } + let sv = stn.state_vector(); + let rv: Vec = (0..dim).map(|i| dsv.get_amplitude(i)).collect(); + let ov: Complex64 = sv.iter().zip(rv.iter()).map(|(a, b)| a.conj() * b).sum(); + if (ov.norm_sqr() - 1.0).abs() > 0.01 { + eprintln!( + "DIVERGE at step {step} ({gate}(q{})): overlap={:.4}", + qubits[0], + ov.norm_sqr() + ); + // Check decomposition phase at the divergence point + // For RX, the inner RZ acts on the SAME qubit after H + let target_q = qubits[0]; + let decomp = pecos_stab_tn::stab_mps::pauli_decomp::decompose_z( + stn.tableau().stabs(), + stn.tableau().destabs(), + target_q, + ); + let phase_ok = pecos_stab_tn::stab_mps::pauli_decomp::verify_decomposition_brute_force( + stn.tableau().stabs(), + stn.tableau().destabs(), + target_q, + &decomp, + ); + eprintln!(" decomp phase correct: {phase_ok}"); + eprintln!(" decomp: {decomp:?}"); + for i in 0..2 { + let sx: Vec = stn.tableau().stabs().row_x[i].iter().collect(); + let sz: Vec = stn.tableau().stabs().row_z[i].iter().collect(); + let sm = stn.tableau().stabs().signs_minus.contains(i); + let si = stn.tableau().stabs().signs_i.contains(i); + let dx: Vec = stn.tableau().destabs().row_x[i].iter().collect(); + let dz: Vec = stn.tableau().destabs().row_z[i].iter().collect(); + let dm = stn.tableau().destabs().signs_minus.contains(i); + let di = stn.tableau().destabs().signs_i.contains(i); + eprintln!( + " S[{i}]: x={sx:?} z={sz:?} m={sm} i={si} D[{i}]: x={dx:?} z={dz:?} m={dm} i={di}" + ); + } + break; + } + } + let stn_sv = stn.state_vector(); + let dsv_sv: Vec = (0..dim).map(|i| dsv.get_amplitude(i)).collect(); + + // Brute-force: compute |ψ⟩ = Σ_x ν_x * D^x * |stab⟩ directly from tableau + let n = 2usize; + let mps_raw = stn.mps().state_vector(); + let gen_matrix = |is_stab: bool, row: usize| -> nalgebra::DMatrix { + let gens = if is_stab { + stn.tableau().stabs() + } else { + stn.tableau().destabs() + }; + let i2 = nalgebra::DMatrix::::identity(2, 2); + let xm = nalgebra::DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + let zm = nalgebra::DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(-1.0, 0.0), + ], + ); + let ym = nalgebra::DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(0.0, -1.0), + Complex64::new(0.0, 1.0), + Complex64::new(0.0, 0.0), + ], + ); + let mut r = nalgebra::DMatrix::from_element(1, 1, Complex64::new(1.0, 0.0)); + for q in 0..n { + let p = match (gens.row_x[row].contains(q), gens.row_z[row].contains(q)) { + (false, false) => &i2, + (true, false) => &xm, + (false, true) => &zm, + (true, true) => &ym, + }; + r = r.kronecker(p); + } + let mut ph = Complex64::new(1.0, 0.0); + if gens.signs_minus.contains(row) { + ph *= Complex64::new(-1.0, 0.0); + } + if gens.signs_i.contains(row) { + ph *= Complex64::new(0.0, 1.0); + } + r * ph + }; + let id4 = nalgebra::DMatrix::::identity(dim, dim); + let mut proj = id4.clone(); + for k in 0..n { + let sk = gen_matrix(true, k); + proj = (&id4 + &sk) * Complex64::new(0.5, 0.0) * &proj; + } + let mut ss = nalgebra::DVector::from_element(dim, Complex64::new(0.0, 0.0)); + ss[0] = Complex64::new(1.0, 0.0); + let ss = &proj * &ss; + let sn: f64 = ss.iter().map(num_complex::Complex::norm_sqr).sum(); + let ss = ss / Complex64::new(sn.sqrt(), 0.0); + let mut psi = nalgebra::DVector::from_element(dim, Complex64::new(0.0, 0.0)); + for (x, &nu) in mps_raw.iter().enumerate() { + if nu.norm_sqr() < 1e-20 { + continue; + } + let mut st = ss.clone(); + for k in 0..n { + if (x >> (n - 1 - k)) & 1 == 1 { + st = &gen_matrix(false, k) * &st; + } + } + psi += st * nu; + } + // Brute-force uses MSB-first (Kronecker convention). Bit-reverse to match DSV (LSB-first). + let mut bru = vec![Complex64::new(0.0, 0.0); dim]; + for (i, &a) in psi.iter().enumerate() { + let mut rev = 0; + for b in 0..n { + if (i >> b) & 1 == 1 { + rev |= 1 << (n - 1 - b); + } + } + bru[rev] = a; + } + let ov_bru: Complex64 = bru + .iter() + .zip(dsv_sv.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + eprintln!("BRU vs DSV overlap: {:.6}", ov_bru.norm_sqr()); + let ov_stn: Complex64 = stn_sv + .iter() + .zip(dsv_sv.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + eprintln!("STN vs DSV overlap: {:.6}", ov_stn.norm_sqr()); + let ov_sb: Complex64 = stn_sv + .iter() + .zip(bru.iter()) + .map(|(a, b)| a.conj() * b) + .sum(); + eprintln!("STN vs BRU overlap: {:.6}", ov_sb.norm_sqr()); + + assert_states_match(&bru, &dsv_sv, "seed502 brute-force vs DSV"); +} + +#[test] +fn test_fuzz_3qubit_deep() { + for seed in 600..700 { + fuzz_circuit(3, 25, seed); + } +} + +#[test] +fn test_fuzz_4qubit_deep() { + for seed in 700..750 { + fuzz_circuit(4, 25, seed); + } +} + +#[test] +fn test_fuzz_6qubit() { + for seed in 750..790 { + fuzz_circuit(6, 15, seed); + } +} + +#[test] +#[ignore = "slow fuzz (~18s debug): run with `cargo test --test verification -- --include-ignored`"] +fn test_fuzz_7qubit() { + for seed in 790..810 { + fuzz_circuit(7, 12, seed); + } +} + +#[test] +#[ignore = "slow fuzz (~80s debug): run with `cargo test --test verification -- --include-ignored`"] +fn test_fuzz_8qubit() { + for seed in 810..820 { + fuzz_circuit(8, 10, seed); + } +} + +#[test] +#[ignore = "deep fuzz (~10min debug, ~30s release): run with `cargo test --release --test verification -- --ignored test_fuzz_deep`"] +fn test_fuzz_deep() { + // Heavy fuzz for pre-release validation. Sweeps 2-8 qubits with many + // seeds and deeper circuits to catch rare corner cases. Run in release + // mode for reasonable turnaround. + for n in 2..=6 { + let depth = 25; + for seed in 0..100u64 { + fuzz_circuit(n, depth, 10000 + seed); + } + } + for n in 7..=8 { + let depth = 15; + for seed in 0..50u64 { + fuzz_circuit(n, depth, 20000 + seed); + } + } +} + +// ============================================================================ +// Measurement probability validation (compare sampling vs state vector) +// ============================================================================ + +/// Build a random circuit using the fuzz RNG, apply it, then check that +/// measurement sampling probabilities match the state vector amplitudes. +fn measurement_probability_check(num_qubits: usize, num_gates: usize, seed: u64) { + // Build the circuit + let mut stn_ref = StabMps::with_seed(num_qubits, seed); + let mut rng_state = seed; + let next_rng = |state: &mut u64| -> u64 { + *state ^= *state << 13; + *state ^= *state >> 7; + *state ^= *state << 17; + *state + }; + + for _ in 0..num_gates { + let gate_type = next_rng(&mut rng_state) % 8; + let q0 = (next_rng(&mut rng_state) % num_qubits as u64) as usize; + let q1 = loop { + let q = (next_rng(&mut rng_state) % num_qubits as u64) as usize; + if q != q0 { + break q; + } + }; + match gate_type { + 0 => { + stn_ref.h(&[QubitId(q0)]); + } + 1 => { + stn_ref.sz(&[QubitId(q0)]); + } + 2 => { + stn_ref.x(&[QubitId(q0)]); + } + 3 => { + stn_ref.cx(&[(QubitId(q0), QubitId(q1))]); + } + 4 => { + stn_ref.cz(&[(QubitId(q0), QubitId(q1))]); + } + 5 => { + let t = Angle64::QUARTER_TURN / 2u64; + stn_ref.rz(t, &[QubitId(q0)]); + } + 6 => { + let angle_bits = next_rng(&mut rng_state); + let angle = Angle64::from_radians( + (angle_bits % 1000) as f64 * 0.001 * std::f64::consts::TAU, + ); + stn_ref.rz(angle, &[QubitId(q0)]); + } + _ => { + let angle_bits = next_rng(&mut rng_state); + let angle = Angle64::from_radians( + (angle_bits % 1000) as f64 * 0.001 * std::f64::consts::TAU, + ); + stn_ref.rx(angle, &[QubitId(q0)]); + } + } + } + + // Get expected probabilities from state vector + let sv = stn_ref.state_vector(); + let dim = 1usize << num_qubits; + let expected_probs: Vec = sv.iter().map(num_complex::Complex::norm_sqr).collect(); + + // For each qubit, check marginal probability matches sampling + for q in 0..num_qubits { + // Expected p(q=0) = sum of |a_i|^2 where bit q of i is 0 + let expected_p0: f64 = (0..dim) + .filter(|&i| (i >> q) & 1 == 0) + .map(|i| expected_probs[i]) + .sum(); + + let z_ev = pecos_stab_tn::stab_mps::measure::z_expectation_value( + stn_ref.tableau(), + stn_ref.mps(), + q, + ) + .re; + let stn_p0 = f64::midpoint(1.0, z_ev).clamp(0.0, 1.0); + + assert!( + (stn_p0 - expected_p0).abs() < 0.001, + "seed={seed} q={q}: p(0) from ={stn_p0:.4} vs state_vector={expected_p0:.4}" + ); + } +} + +#[test] +fn test_measurement_probabilities_2qubit() { + for seed in 1000..1100 { + measurement_probability_check(2, 10, seed); + } +} + +#[test] +fn test_measurement_probabilities_3qubit() { + for seed in 1100..1200 { + measurement_probability_check(3, 12, seed); + } +} + +#[test] +fn test_measurement_probabilities_4qubit() { + for seed in 1200..1280 { + measurement_probability_check(4, 15, seed); + } +} + +#[test] +fn test_measurement_probabilities_5qubit() { + for seed in 1280..1310 { + measurement_probability_check(5, 10, seed); + } +} + +// ============================================================================ +// Disentangle validation +// ============================================================================ + +#[test] +#[allow(clippy::type_complexity)] +fn test_disentangle_various_circuits() { + // Verify disentangle preserves state for several circuits + let circuits: Vec> = vec![ + Box::new(|stn: &mut StabMps| { + let t = Angle64::QUARTER_TURN / 2u64; + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.rz(t, &[QubitId(0)]); + }), + Box::new(|stn: &mut StabMps| { + let t = Angle64::QUARTER_TURN / 2u64; + stn.h(&[QubitId(0)]); + stn.h(&[QubitId(1)]); + stn.rz(t, &[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.rz(t, &[QubitId(1)]); + }), + Box::new(|stn: &mut StabMps| { + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.cx(&[(QubitId(1), QubitId(2))]); + stn.rz(Angle64::from_radians(0.7), &[QubitId(1)]); + }), + ]; + + for (i, build) in circuits.iter().enumerate() { + let mut stn = StabMps::new(3); + build(&mut stn); + let sv_before = stn.state_vector(); + let _gates = stn.disentangle(5); + let sv_after = stn.state_vector(); + assert_states_match(&sv_before, &sv_after, &format!("disentangle circuit {i}")); + } +} + +// ============================================================================ +// Edge cases +// ============================================================================ + +#[test] +fn test_single_qubit_identity() { + // No gates at all + let (stn_sv, crz_sv) = run_circuit_on_both(1, &[], 42); + assert_states_match(&stn_sv, &crz_sv, "identity 1-qubit"); +} + +#[test] +fn test_only_cliffords_4qubit() { + let gates = vec![ + ("h", vec![0], None), + ("h", vec![1], None), + ("cx", vec![0, 1], None), + ("cz", vec![2, 3], None), + ("h", vec![2], None), + ("sz", vec![3], None), + ("cx", vec![1, 2], None), + ("cx", vec![3, 0], None), + ("h", vec![0], None), + ("h", vec![1], None), + ("h", vec![2], None), + ("h", vec![3], None), + ]; + let (stn_sv, crz_sv) = run_circuit_on_both(4, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "pure Clifford 4-qubit"); +} + +#[test] +fn test_t_on_every_qubit_product_state() { + // T on each qubit of a product state |+...+> + let n = 4; + let t = Angle64::QUARTER_TURN / 2u64; + let mut gates: Vec<(&str, Vec, Option)> = Vec::new(); + for q in 0..n { + gates.push(("h", vec![q], None)); + } + for q in 0..n { + gates.push(("rz", vec![q], Some(t))); + } + let (stn_sv, crz_sv) = run_circuit_on_both(n, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "T on product state"); +} + +#[test] +fn test_tdg_gate() { + // T-dagger = RZ(-pi/4) + let tdg = -(Angle64::QUARTER_TURN / 2u64); + let gates = vec![("h", vec![0], None), ("rz", vec![0], Some(tdg))]; + let (stn_sv, crz_sv) = run_circuit_on_both(1, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "Tdg gate"); +} + +#[test] +fn test_rz_near_zero_angle() { + // Very small angle -- should behave like identity + let tiny = Angle64::from_radians(1e-6); + let gates = vec![("h", vec![0], None), ("rz", vec![0], Some(tiny))]; + let (stn_sv, crz_sv) = run_circuit_on_both(1, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "near-zero RZ"); +} + +#[test] +fn test_rz_near_pi() { + // Angle near pi -- should behave like Z gate + let near_pi = Angle64::from_radians(std::f64::consts::PI - 1e-6); + let gates = vec![("h", vec![0], None), ("rz", vec![0], Some(near_pi))]; + let (stn_sv, crz_sv) = run_circuit_on_both(1, &gates, 42); + assert_states_match(&stn_sv, &crz_sv, "near-pi RZ"); +} + +#[test] +fn test_stn_reset_and_reuse() { + let mut stn = StabMps::new(2); + stn.h(&[QubitId(0)]); + stn.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + + stn.reset(); + + // After reset, should behave like fresh simulator + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + let sv = stn.state_vector(); + let norm: f64 = sv.iter().map(num_complex::Complex::norm_sqr).sum(); + assert!( + (norm - 1.0).abs() < 0.01, + "norm after reset+circuit: {norm}" + ); +} + +// ============================================================================ +// MAST-specific verification +// ============================================================================ + +#[test] +fn test_mast_multiple_t_gates() { + // Multiple T gates via MAST on entangled qubits + let mut mast = Mast::with_seed(3, 10, 42); + mast.h(&[QubitId(0)]); + mast.cx(&[(QubitId(0), QubitId(1))]); + mast.cx(&[(QubitId(1), QubitId(2))]); + // GHZ state + + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(1)]); + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(2)]); + + assert_eq!(mast.num_ancillas_used(), 3); + assert!( + mast.mps().norm_squared() > 0.5, + "norm should be reasonable: {}", + mast.mps().norm_squared() + ); +} + +#[test] +fn test_mast_3qubit_ghz_correlation() { + // GHZ + T via MAST: all measurements should be correlated + let num_trials = 100; + let mut all_corr = 0; + for trial in 0..num_trials { + let mut mast = Mast::with_seed(3, 10, 40_000 + trial); + mast.h(&[QubitId(0)]); + mast.cx(&[(QubitId(0), QubitId(1))]); + mast.cx(&[(QubitId(1), QubitId(2))]); + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + + let r0 = mast.mz(&[QubitId(0)])[0].outcome; + let r1 = mast.mz(&[QubitId(1)])[0].outcome; + let r2 = mast.mz(&[QubitId(2)])[0].outcome; + if r0 == r1 && r1 == r2 { + all_corr += 1; + } + } + let rate = f64::from(all_corr) / num_trials as f64; + assert!( + rate > 0.90, + "GHZ+T MAST correlation {rate:.2} should be > 0.90" + ); +} + +#[test] +fn test_mast_t_then_measure_then_more() { + // Apply T, measure, then apply more gates + let mut mast = Mast::with_seed(2, 4, 42); + mast.h(&[QubitId(0)]); + mast.rz(Angle64::QUARTER_TURN / 2u64, &[QubitId(0)]); + let _r0 = mast.mz(&[QubitId(0)])[0].outcome; + + // After measurement, apply more gates on q1 + mast.h(&[QubitId(1)]); + let r1 = mast.mz(&[QubitId(1)])[0].outcome; + // q1 was in |0>, H puts it in |+>, measurement is random + let _ = r1; // Just verify it doesn't panic +} + +// ============================================================================ +// RZZ fuzz tests +// ============================================================================ + +/// Fuzz with RZZ gates included in the gate set. +fn fuzz_with_rzz(num_qubits: usize, num_gates: usize, seed: u64) { + let mut stn = StabMps::with_seed(num_qubits, seed); + let mut dsv = pecos_simulators::DenseStateVec::new(num_qubits); + + let mut rng_state = seed; + let next_rng = |state: &mut u64| -> u64 { + *state ^= *state << 13; + *state ^= *state >> 7; + *state ^= *state << 17; + *state + }; + + for _ in 0..num_gates { + let gate_type = next_rng(&mut rng_state) % 10; // expanded set includes rzz + let q0 = (next_rng(&mut rng_state) % num_qubits as u64) as usize; + let q1 = loop { + let q = (next_rng(&mut rng_state) % num_qubits as u64) as usize; + if q != q0 { + break q; + } + }; + + match gate_type { + 0 => { + stn.h(&[QubitId(q0)]); + dsv.h(&[QubitId(q0)]); + } + 1 => { + stn.sz(&[QubitId(q0)]); + dsv.sz(&[QubitId(q0)]); + } + 2 => { + stn.x(&[QubitId(q0)]); + dsv.x(&[QubitId(q0)]); + } + 3 => { + stn.cx(&[(QubitId(q0), QubitId(q1))]); + dsv.cx(&[(QubitId(q0), QubitId(q1))]); + } + 4 => { + stn.cz(&[(QubitId(q0), QubitId(q1))]); + dsv.cz(&[(QubitId(q0), QubitId(q1))]); + } + 5 => { + let t = Angle64::QUARTER_TURN / 2u64; + stn.rz(t, &[QubitId(q0)]); + dsv.rz(t, &[QubitId(q0)]); + } + 6 => { + let ab = next_rng(&mut rng_state); + let a = Angle64::from_radians((ab % 1000) as f64 * 0.001 * std::f64::consts::TAU); + stn.rz(a, &[QubitId(q0)]); + dsv.rz(a, &[QubitId(q0)]); + } + 7 => { + let ab = next_rng(&mut rng_state); + let a = Angle64::from_radians((ab % 1000) as f64 * 0.001 * std::f64::consts::TAU); + stn.rx(a, &[QubitId(q0)]); + dsv.rx(a, &[QubitId(q0)]); + } + 8 | 9 => { + // RZZ gate + let ab = next_rng(&mut rng_state); + let a = Angle64::from_radians((ab % 1000) as f64 * 0.001 * std::f64::consts::TAU); + let pairs = [(QubitId(q0), QubitId(q1))]; + stn.rzz(a, &pairs); + dsv.rzz(a, &pairs); + } + _ => {} + } + } + + let stn_sv = stn.state_vector(); + let dim = 1usize << num_qubits; + let ref_sv: Vec = (0..dim).map(|i| dsv.get_amplitude(i)).collect(); + let tol = 0.01 + 0.002 * num_gates as f64; + assert_states_close( + &stn_sv, + &ref_sv, + tol, + &format!("rzz fuzz n={num_qubits} g={num_gates} seed={seed}"), + ); +} + +#[test] +fn test_fuzz_rzz_2qubit() { + for seed in 2000..2100 { + fuzz_with_rzz(2, 12, seed); + } +} + +#[test] +fn test_fuzz_rzz_3qubit() { + for seed in 2100..2150 { + fuzz_with_rzz(3, 12, seed); + } +} + +#[test] +fn test_fuzz_rzz_4qubit() { + for seed in 2150..2200 { + fuzz_with_rzz(4, 12, seed); + } +} + +// ============================================================================ +// Sequential measurement tests +// ============================================================================ + +#[test] +fn test_sequential_measurement_correlations() { + // Apply non-Clifford gates, measure a qubit, apply more gates, measure again. + // Repeat many times and check that outcome distributions are consistent. + let num_trials = 200; + let mut outcomes = [[0u32; 2]; 2]; // [q0_outcome][q1_outcome] + + for trial in 0..num_trials { + let mut stn = StabMps::with_seed(2, 5000 + trial); + let mut dsv = pecos_simulators::DenseStateVec::new(2); + + // Prepare entangled state with non-Clifford component + stn.h(&[QubitId(0)]); + dsv.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + dsv.cx(&[(QubitId(0), QubitId(1))]); + let t = Angle64::QUARTER_TURN / 2u64; + stn.rz(t, &[QubitId(0)]); + dsv.rz(t, &[QubitId(0)]); + + // Measure q0 + let r0_stn = stn.mz(&[QubitId(0)])[0].outcome; + + // Apply more gates after measurement + stn.h(&[QubitId(1)]); + stn.rz(t, &[QubitId(1)]); + + // Measure q1 + let r1_stn = stn.mz(&[QubitId(1)])[0].outcome; + + outcomes[usize::from(r0_stn)][usize::from(r1_stn)] += 1; + } + + // Bell+T: q0 and q1 are correlated before first measurement. + // After measuring q0, the state collapses. The second measurement + // should give a definite result. Just check no panics and + // reasonable distribution. + let total: u32 = outcomes.iter().flat_map(|r| r.iter()).sum(); + assert_eq!(total, num_trials as u32); + // Both q0=0 and q0=1 should appear (non-deterministic) + let q0_zero: u32 = outcomes[0].iter().sum(); + let q0_one: u32 = outcomes[1].iter().sum(); + assert!(q0_zero > 10, "q0=0 too rare: {q0_zero}"); + assert!(q0_one > 10, "q0=1 too rare: {q0_one}"); +} + +#[test] +fn test_measure_apply_measure_3qubit() { + // GHZ + T, measure q0, then H+T on q1, measure q1, then measure q2. + for trial in 0..100u64 { + let mut stn = StabMps::with_seed(3, 6000 + trial); + let t = Angle64::QUARTER_TURN / 2u64; + + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.cx(&[(QubitId(1), QubitId(2))]); + stn.rz(t, &[QubitId(1)]); + + let r0 = stn.mz(&[QubitId(0)])[0].outcome; + + // After measuring q0, apply more gates + stn.h(&[QubitId(1)]); + stn.rz(t, &[QubitId(1)]); + + let r1 = stn.mz(&[QubitId(1)])[0].outcome; + let r2 = stn.mz(&[QubitId(2)])[0].outcome; + + // q0 and q2 were in GHZ: after measuring q0, q2 should be deterministic + // (same as q0 due to GHZ correlation, modulo the T gate on q1) + let _ = (r0, r1, r2); // Just verify no panics + } +} + +// ============================================================================ +// MAST vs STN measurement comparison +// ============================================================================ + +#[test] +fn test_mast_matches_stn_exact_probabilities_2q() { + // Compare MAST's sampled distribution to STN's EXACT probabilities + // (not STN's samples). STN's `prob_bitstring` gives the analytic + // value; MAST must sample from this distribution within 5σ. + let t = Angle64::QUARTER_TURN / 2u64; + + // Exact probabilities from STN. + let mut exact_probs = [0.0_f64; 4]; + let mut stn_for_probs = StabMps::with_seed(2, 1234); + stn_for_probs.h(&[QubitId(0)]); + stn_for_probs.cx(&[(QubitId(0), QubitId(1))]); + stn_for_probs.rz(t, &[QubitId(0)]); + stn_for_probs.h(&[QubitId(1)]); + stn_for_probs.rz(t, &[QubitId(1)]); + stn_for_probs.flush(); + // prob_bitstring is MSB-first: bitstring[k] is qubit (n-1-k). For a + // LSB-first integer index `i` (q_k = (i >> k) & 1), bitstring = + // [q_{n-1}, q_{n-2}, ..., q_0]. + for (i, ep) in exact_probs.iter_mut().enumerate().take(4) { + let bits = [(i & 2) != 0, (i & 1) != 0]; + *ep = stn_for_probs.prob_bitstring(&bits); + } + let total: f64 = exact_probs.iter().sum(); + assert!( + (total - 1.0).abs() < 1e-9, + "exact probs must sum to 1, got {total}: {exact_probs:?}" + ); + + // Sample MAST many times and compare to exact. + let num_trials = 5000; + let mut mast_counts = [0u32; 4]; + for trial in 0..num_trials { + let seed = 7000 + trial; + let mut mast = Mast::with_seed(2, 4, seed); + mast.h(&[QubitId(0)]); + mast.cx(&[(QubitId(0), QubitId(1))]); + mast.rz(t, &[QubitId(0)]); + mast.h(&[QubitId(1)]); + mast.rz(t, &[QubitId(1)]); + let m0 = mast.mz(&[QubitId(0)])[0].outcome; + let m1 = mast.mz(&[QubitId(1)])[0].outcome; + mast_counts[usize::from(m0) | (usize::from(m1) << 1)] += 1; + } + + // 5σ bound on |p_sample - p_exact|: sqrt(p(1-p)/N) × 5 ≤ 0.04 for + // N=5000, any p. Leaves generous room for sampling noise. + for i in 0..4 { + let pe = exact_probs[i]; + let pm = f64::from(mast_counts[i]) / num_trials as f64; + let sigma = (pe * (1.0 - pe) / num_trials as f64).sqrt().max(1e-6); + let deviation = (pe - pm).abs() / sigma; + assert!( + deviation < 5.0, + "outcome {i}: exact={pe:.4} MAST={pm:.4}, deviation {deviation:.1}σ" + ); + } +} + +#[test] +fn test_mast_matches_stn_exact_probabilities_3q() { + let t = Angle64::QUARTER_TURN / 2u64; + + // Exact probs from STN. + let mut exact_probs = [0.0_f64; 8]; + let mut stn = StabMps::with_seed(3, 1234); + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.h(&[QubitId(2)]); + stn.rz(t, &[QubitId(0)]); + stn.rz(t, &[QubitId(2)]); + stn.cx(&[(QubitId(1), QubitId(2))]); + stn.flush(); + // prob_bitstring is MSB-first: bitstring = [q_{n-1}, ..., q_0]. + for (i, ep) in exact_probs.iter_mut().enumerate().take(8) { + let bits = [(i & 4) != 0, (i & 2) != 0, (i & 1) != 0]; + *ep = stn.prob_bitstring(&bits); + } + let total: f64 = exact_probs.iter().sum(); + assert!( + (total - 1.0).abs() < 1e-9, + "probs sum != 1: {exact_probs:?}" + ); + + let num_trials = 5000; + let mut mast_counts = [0u32; 8]; + for trial in 0..num_trials { + let seed = 8000 + trial; + let mut mast = Mast::with_seed(3, 4, seed); + mast.h(&[QubitId(0)]); + mast.cx(&[(QubitId(0), QubitId(1))]); + mast.h(&[QubitId(2)]); + mast.rz(t, &[QubitId(0)]); + mast.rz(t, &[QubitId(2)]); + mast.cx(&[(QubitId(1), QubitId(2))]); + let r: Vec = mast + .mz(&[QubitId(0), QubitId(1), QubitId(2)]) + .iter() + .map(|m| m.outcome) + .collect(); + mast_counts[usize::from(r[0]) | (usize::from(r[1]) << 1) | (usize::from(r[2]) << 2)] += 1; + } + + for i in 0..8 { + let pe = exact_probs[i]; + let pm = f64::from(mast_counts[i]) / num_trials as f64; + let sigma = (pe * (1.0 - pe) / num_trials as f64).sqrt().max(1e-6); + let deviation = (pe - pm).abs() / sigma; + assert!( + deviation < 5.0, + "3q outcome {i}: exact={pe:.4} MAST={pm:.4}, dev {deviation:.1}σ" + ); + } +} + +// ============================================================================ +// Large bond dimension stress tests +// ============================================================================ + +#[test] +fn test_many_t_gates_bond_dim_growth() { + // Apply T gates to all qubits of an entangled state. + // Bond dim grows but should stay bounded by max_bond_dim. + let num_qubits = 6; + let t = Angle64::QUARTER_TURN / 2u64; + + let mut stn = StabMps::builder(num_qubits).max_bond_dim(32).build(); + let mut dsv = pecos_simulators::DenseStateVec::new(num_qubits); + + // Create full entanglement: H on all, then CX chain + for q in 0..num_qubits { + stn.h(&[QubitId(q)]); + dsv.h(&[QubitId(q)]); + } + for q in 0..num_qubits - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + dsv.cx(&[(QubitId(q), QubitId(q + 1))]); + } + + // Apply T on every qubit — each one grows bond dim + for q in 0..num_qubits { + stn.rz(t, &[QubitId(q)]); + dsv.rz(t, &[QubitId(q)]); + } + + assert!( + stn.max_bond_dim() <= 32, + "bond dim {} exceeds limit", + stn.max_bond_dim() + ); + + let stn_sv = stn.state_vector(); + let dim = 1usize << num_qubits; + let ref_sv: Vec = (0..dim).map(|i| dsv.get_amplitude(i)).collect(); + assert_states_close(&stn_sv, &ref_sv, 0.05, "many T gates on entangled state"); +} + +#[test] +fn test_ghz_plus_t_ladder() { + // GHZ state, then T on alternating qubits, then entangling again. + let num_qubits = 5; + let t = Angle64::QUARTER_TURN / 2u64; + + let mut stn = StabMps::builder(num_qubits).max_bond_dim(64).build(); + let mut dsv = pecos_simulators::DenseStateVec::new(num_qubits); + + // GHZ: H(0), CX chain + stn.h(&[QubitId(0)]); + dsv.h(&[QubitId(0)]); + for q in 0..num_qubits - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + dsv.cx(&[(QubitId(q), QubitId(q + 1))]); + } + + // T on even qubits + for q in (0..num_qubits).step_by(2) { + stn.rz(t, &[QubitId(q)]); + dsv.rz(t, &[QubitId(q)]); + } + + // More entangling + for q in (0..num_qubits - 1).rev() { + stn.cx(&[(QubitId(q + 1), QubitId(q))]); + dsv.cx(&[(QubitId(q + 1), QubitId(q))]); + } + + // T on odd qubits + for q in (1..num_qubits).step_by(2) { + stn.rz(t, &[QubitId(q)]); + dsv.rz(t, &[QubitId(q)]); + } + + let stn_sv = stn.state_vector(); + let dim = 1usize << num_qubits; + let ref_sv: Vec = (0..dim).map(|i| dsv.get_amplitude(i)).collect(); + assert_states_close(&stn_sv, &ref_sv, 0.05, "GHZ+T ladder"); +} + +#[test] +fn test_repeated_t_layers_4qubit() { + // Multiple layers of T gates with entangling between layers. + // This is the worst case for bond dim growth. + let num_qubits = 4; + let t = Angle64::QUARTER_TURN / 2u64; + + let mut stn = StabMps::with_seed(num_qubits, 42); + let mut dsv = pecos_simulators::DenseStateVec::new(num_qubits); + + for _layer in 0..3 { + // H + CX entangling layer + for q in 0..num_qubits { + stn.h(&[QubitId(q)]); + dsv.h(&[QubitId(q)]); + } + for q in 0..num_qubits - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + dsv.cx(&[(QubitId(q), QubitId(q + 1))]); + } + // T layer + for q in 0..num_qubits { + stn.rz(t, &[QubitId(q)]); + dsv.rz(t, &[QubitId(q)]); + } + } + + let stn_sv = stn.state_vector(); + let dim = 1usize << num_qubits; + let ref_sv: Vec = (0..dim).map(|i| dsv.get_amplitude(i)).collect(); + // 3 layers * 4 T gates = 12 non-Clifford gates, deep circuit + assert_states_close(&stn_sv, &ref_sv, 0.1, "repeated T layers 4q"); +} + +#[test] +fn test_bond_dim_respects_config() { + // Verify that max_bond_dim is respected even under heavy non-Clifford load. + let num_qubits = 4; + let t = Angle64::QUARTER_TURN / 2u64; + let max_chi = 8; + + let mut stn = StabMps::builder(num_qubits).max_bond_dim(max_chi).build(); + + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.cx(&[(QubitId(1), QubitId(2))]); + stn.cx(&[(QubitId(2), QubitId(3))]); + + // Apply many T gates to push bond dim up + for _ in 0..5 { + for q in 0..num_qubits { + stn.rz(t, &[QubitId(q)]); + } + } + + assert!( + stn.max_bond_dim() <= max_chi, + "bond dim {} exceeds configured max {max_chi}", + stn.max_bond_dim() + ); + // MPS should still be approximately normalized + assert!( + (stn.mps().norm_squared() - 1.0).abs() < 0.5, + "MPS norm too far from 1: {}", + stn.mps().norm_squared() + ); +} + +// ============================================================================ +// Tdg (negative angle) fuzz +// ============================================================================ + +/// Fuzz with Tdg and negative-angle RZ gates. +fn fuzz_with_tdg(num_qubits: usize, num_gates: usize, seed: u64) { + let mut stn = StabMps::with_seed(num_qubits, seed); + let mut dsv = pecos_simulators::DenseStateVec::new(num_qubits); + + let mut rng_state = seed; + let next_rng = |state: &mut u64| -> u64 { + *state ^= *state << 13; + *state ^= *state >> 7; + *state ^= *state << 17; + *state + }; + + for _ in 0..num_gates { + let gate_type = next_rng(&mut rng_state) % 10; + let q0 = (next_rng(&mut rng_state) % num_qubits as u64) as usize; + let q1 = loop { + let q = (next_rng(&mut rng_state) % num_qubits as u64) as usize; + if q != q0 { + break q; + } + }; + match gate_type { + 0 => { + stn.h(&[QubitId(q0)]); + dsv.h(&[QubitId(q0)]); + } + 1 => { + stn.sz(&[QubitId(q0)]); + dsv.sz(&[QubitId(q0)]); + } + 2 => { + stn.x(&[QubitId(q0)]); + dsv.x(&[QubitId(q0)]); + } + 3 => { + stn.cx(&[(QubitId(q0), QubitId(q1))]); + dsv.cx(&[(QubitId(q0), QubitId(q1))]); + } + 4 => { + // T gate + let t = Angle64::QUARTER_TURN / 2u64; + stn.rz(t, &[QubitId(q0)]); + dsv.rz(t, &[QubitId(q0)]); + } + 5 => { + // Tdg gate (negative T) + let tdg = -(Angle64::QUARTER_TURN / 2u64); + stn.rz(tdg, &[QubitId(q0)]); + dsv.rz(tdg, &[QubitId(q0)]); + } + 6 => { + // Random negative-angle RZ + let ab = next_rng(&mut rng_state); + let a = -Angle64::from_radians((ab % 1000) as f64 * 0.001 * std::f64::consts::TAU); + stn.rz(a, &[QubitId(q0)]); + dsv.rz(a, &[QubitId(q0)]); + } + 7 => { + // Random positive-angle RZ + let ab = next_rng(&mut rng_state); + let a = Angle64::from_radians((ab % 1000) as f64 * 0.001 * std::f64::consts::TAU); + stn.rz(a, &[QubitId(q0)]); + dsv.rz(a, &[QubitId(q0)]); + } + 8 => { + // RX with negative angle + let ab = next_rng(&mut rng_state); + let a = -Angle64::from_radians((ab % 1000) as f64 * 0.001 * std::f64::consts::TAU); + stn.rx(a, &[QubitId(q0)]); + dsv.rx(a, &[QubitId(q0)]); + } + _ => { + stn.cz(&[(QubitId(q0), QubitId(q1))]); + dsv.cz(&[(QubitId(q0), QubitId(q1))]); + } + } + } + let stn_sv = stn.state_vector(); + let dim = 1usize << num_qubits; + let ref_sv: Vec = (0..dim).map(|i| dsv.get_amplitude(i)).collect(); + let tol = 0.01 + 0.002 * num_gates as f64; + assert_states_close( + &stn_sv, + &ref_sv, + tol, + &format!("tdg fuzz n={num_qubits} g={num_gates} seed={seed}"), + ); +} + +#[test] +fn test_fuzz_tdg_2qubit() { + for seed in 3000..3100 { + fuzz_with_tdg(2, 12, seed); + } +} + +#[test] +fn test_fuzz_szdg_circuits() { + // Include szdg in the gate set to test the default sz.sz.sz path + for seed in 3200..3250 { + let mut stn = StabMps::with_seed(2, seed); + let mut dsv = pecos_simulators::DenseStateVec::new(2); + let mut rng_state = seed; + let next_rng = |state: &mut u64| -> u64 { + *state ^= *state << 13; + *state ^= *state >> 7; + *state ^= *state << 17; + *state + }; + for _ in 0..12 { + let gt = next_rng(&mut rng_state) % 8; + let q0 = (next_rng(&mut rng_state) % 2) as usize; + let q1 = 1 - q0; + match gt { + 0 => { + stn.h(&[QubitId(q0)]); + dsv.h(&[QubitId(q0)]); + } + 1 => { + stn.sz(&[QubitId(q0)]); + dsv.sz(&[QubitId(q0)]); + } + 2 => { + stn.szdg(&[QubitId(q0)]); + dsv.szdg(&[QubitId(q0)]); + } + 3 => { + stn.cx(&[(QubitId(q0), QubitId(q1))]); + dsv.cx(&[(QubitId(q0), QubitId(q1))]); + } + 4 => { + let t = Angle64::QUARTER_TURN / 2u64; + stn.rz(t, &[QubitId(q0)]); + dsv.rz(t, &[QubitId(q0)]); + } + 5 => { + let tdg = -(Angle64::QUARTER_TURN / 2u64); + stn.rz(tdg, &[QubitId(q0)]); + dsv.rz(tdg, &[QubitId(q0)]); + } + 6 => { + let ab = next_rng(&mut rng_state); + let a = + Angle64::from_radians((ab % 1000) as f64 * 0.001 * std::f64::consts::TAU); + stn.rz(a, &[QubitId(q0)]); + dsv.rz(a, &[QubitId(q0)]); + } + _ => { + stn.cz(&[(QubitId(q0), QubitId(q1))]); + dsv.cz(&[(QubitId(q0), QubitId(q1))]); + } + } + } + let stn_sv = stn.state_vector(); + let ref_sv: Vec = (0..4).map(|i| dsv.get_amplitude(i)).collect(); + assert_states_close(&stn_sv, &ref_sv, 0.04, &format!("szdg fuzz seed={seed}")); + } +} + +#[test] +fn test_fuzz_tdg_3qubit() { + for seed in 3100..3150 { + fuzz_with_tdg(3, 12, seed); + } +} + +// ============================================================================ +// Post-measurement state correctness +// ============================================================================ + +#[test] +fn test_post_measurement_state_consistency() { + // After measuring q0, verify the STN state is internally consistent: + // the z_expectation_value of unmeasured qubits should match the + // probabilities from the state vector. + let t = Angle64::QUARTER_TURN / 2u64; + + for trial in 0..100u64 { + let seed = 9000 + trial; + let mut stn = StabMps::with_seed(2, seed); + + // Build non-trivial state + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.rz(t, &[QubitId(0)]); + stn.h(&[QubitId(1)]); + stn.rz(t, &[QubitId(1)]); + + // Check before measurement matches state vector + let sv_before = stn.state_vector(); + let ev_z0_sv: f64 = sv_before + .iter() + .enumerate() + .map(|(i, a)| { + let sign = if i & 1 == 0 { 1.0 } else { -1.0 }; + sign * a.norm_sqr() + }) + .sum(); + let ev_z0_mps = + pecos_stab_tn::stab_mps::measure::z_expectation_value(stn.tableau(), stn.mps(), 0).re; + assert!( + (ev_z0_sv - ev_z0_mps).abs() < 0.01, + "trial {trial}: pre-meas sv={ev_z0_sv:.4} mps={ev_z0_mps:.4}" + ); + + // Measure q0 + let r0 = stn.mz(&[QubitId(0)])[0].outcome; + + // After measurement: from expectation value should match state_vector + let sv_after = stn.state_vector(); + let ev_z1_sv: f64 = sv_after + .iter() + .enumerate() + .map(|(i, a)| { + let sign = if (i >> 1) & 1 == 0 { 1.0 } else { -1.0 }; + sign * a.norm_sqr() + }) + .sum(); + let ev_z1_mps = + pecos_stab_tn::stab_mps::measure::z_expectation_value(stn.tableau(), stn.mps(), 1).re; + assert!( + (ev_z1_sv - ev_z1_mps).abs() < 0.05, + "trial {trial}: post-meas sv={ev_z1_sv:.4} mps={ev_z1_mps:.4}" + ); + + // Check after measurement + let ev_z0_after = + pecos_stab_tn::stab_mps::measure::z_expectation_value(stn.tableau(), stn.mps(), 0).re; + let expected_ev = if r0 { -1.0 } else { 1.0 }; + // Also check via state vector (brute-force) + let sv_after = stn.state_vector(); + let ev_z0_sv: f64 = sv_after + .iter() + .enumerate() + .map(|(i, a)| { + let sign = if i & 1 == 0 { 1.0 } else { -1.0 }; + sign * a.norm_sqr() + }) + .sum(); + if (ev_z0_after - expected_ev).abs() > 0.1 { + eprintln!( + "trial {trial}: outcome={r0}, mps={ev_z0_after:.4} sv={ev_z0_sv:.4} (expected {expected_ev})" + ); + // Print decomposition of Z_0 after measurement + let decomp = pecos_stab_tn::stab_mps::pauli_decomp::decompose_z( + stn.tableau().stabs(), + stn.tableau().destabs(), + 0, + ); + eprintln!(" Z_0 decomp after meas: {decomp:?}"); + eprintln!(" MPS bonds: {:?}", stn.mps().bond_dims()); + } + + // Re-measure q0: should give same outcome (collapsed state) + let r0_again = stn.mz(&[QubitId(0)]); + assert_eq!( + r0_again[0].outcome, r0, + "trial {trial}: re-measurement should give same outcome, ={ev_z0_after:.4}" + ); + } +} + +#[test] +fn test_post_measurement_multisite_collapse() { + // Trigger a multi-site DestabilizerFlip measurement (flip + sign sites). + // Then re-measure to verify collapse. + let t = Angle64::QUARTER_TURN / 2u64; + + for trial in 0..50u64 { + let seed = 9200 + trial; + let mut stn = StabMps::with_seed(3, seed); + + // Build state where Z_0 decomposes with both flip and sign sites + stn.h(&[QubitId(0)]); + stn.h(&[QubitId(1)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.cx(&[(QubitId(1), QubitId(2))]); + stn.rz(t, &[QubitId(0)]); + stn.rz(t, &[QubitId(1)]); + stn.h(&[QubitId(0)]); // Change basis to make Z_0 decomposition multi-site + + // Measure q0 + let r0 = stn.mz(&[QubitId(0)])[0].outcome; + + // Re-measure: should give same outcome + let r0_again = stn.mz(&[QubitId(0)]); + assert_eq!( + r0_again[0].outcome, r0, + "trial {trial}: multi-site re-measurement should give same outcome" + ); + + // Verify expectation value consistency: from MPS should match state_vector + let sv = stn.state_vector(); + for q in 0..3 { + let ev_sv: f64 = sv + .iter() + .enumerate() + .map(|(i, a)| { + let sign = if (i >> q) & 1 == 0 { 1.0 } else { -1.0 }; + sign * a.norm_sqr() + }) + .sum(); + let ev_mps = + pecos_stab_tn::stab_mps::measure::z_expectation_value(stn.tableau(), stn.mps(), q) + .re; + assert!( + (ev_sv - ev_mps).abs() < 0.05, + "trial {trial}: post-multisite-meas sv={ev_sv:.4} mps={ev_mps:.4}" + ); + } + } +} + +#[test] +fn test_post_measurement_state_3qubit() { + // Measure q0 on a 3-qubit entangled state, then check internal consistency. + let t = Angle64::QUARTER_TURN / 2u64; + + for trial in 0..50u64 { + let seed = 9500 + trial; + let mut stn = StabMps::with_seed(3, seed); + + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.h(&[QubitId(2)]); + stn.rz(t, &[QubitId(1)]); + + let _ = stn.mz(&[QubitId(0)])[0].outcome; + + // After measurement: check expectation values match state vector + let sv = stn.state_vector(); + for q in 1..3 { + let ev_sv: f64 = sv + .iter() + .enumerate() + .map(|(i, a)| { + let sign = if (i >> q) & 1 == 0 { 1.0 } else { -1.0 }; + sign * a.norm_sqr() + }) + .sum(); + let ev_mps = + pecos_stab_tn::stab_mps::measure::z_expectation_value(stn.tableau(), stn.mps(), q) + .re; + assert!( + (ev_sv - ev_mps).abs() < 0.05, + "trial {trial}: post-meas sv={ev_sv:.4} mps={ev_mps:.4}" + ); + } + } +} + +// ============================================================================ +// Single-qubit circuit fuzz +// ============================================================================ + +#[test] +fn test_fuzz_single_qubit() { + // Single-qubit circuits: always Stabilizer decomposition path. + for seed in 4000..4200 { + let mut stn = StabMps::with_seed(1, seed); + let mut dsv = pecos_simulators::DenseStateVec::new(1); + + let mut rng_state = seed; + let next_rng = |state: &mut u64| -> u64 { + *state ^= *state << 13; + *state ^= *state >> 7; + *state ^= *state << 17; + *state + }; + + for _ in 0..15 { + let gate_type = next_rng(&mut rng_state) % 6; + match gate_type { + 0 => { + stn.h(&[QubitId(0)]); + dsv.h(&[QubitId(0)]); + } + 1 => { + stn.sz(&[QubitId(0)]); + dsv.sz(&[QubitId(0)]); + } + 2 => { + let t = Angle64::QUARTER_TURN / 2u64; + stn.rz(t, &[QubitId(0)]); + dsv.rz(t, &[QubitId(0)]); + } + 3 => { + let tdg = -(Angle64::QUARTER_TURN / 2u64); + stn.rz(tdg, &[QubitId(0)]); + dsv.rz(tdg, &[QubitId(0)]); + } + 4 => { + let ab = next_rng(&mut rng_state); + let a = + Angle64::from_radians((ab % 1000) as f64 * 0.001 * std::f64::consts::TAU); + stn.rz(a, &[QubitId(0)]); + dsv.rz(a, &[QubitId(0)]); + } + _ => { + let ab = next_rng(&mut rng_state); + let a = + Angle64::from_radians((ab % 1000) as f64 * 0.001 * std::f64::consts::TAU); + stn.rx(a, &[QubitId(0)]); + dsv.rx(a, &[QubitId(0)]); + } + } + } + let stn_sv = stn.state_vector(); + let ref_sv: Vec = (0..2).map(|i| dsv.get_amplitude(i)).collect(); + assert_states_close(&stn_sv, &ref_sv, 0.01, &format!("1q fuzz seed={seed}")); + } +} + +// ============================================================================ +// RZZ at Clifford angles +// ============================================================================ + +#[test] +fn test_rzz_clifford_angles() { + // RZZ at Clifford angles should not grow bond dimension. + let clifford_angles = [ + Angle64::ZERO, + Angle64::QUARTER_TURN, // pi/2 + Angle64::HALF_TURN, // pi + Angle64::THREE_QUARTERS_TURN, // 3pi/2 + ]; + + for &angle in &clifford_angles { + let mut stn = StabMps::with_seed(3, 42); + let mut dsv = pecos_simulators::DenseStateVec::new(3); + + // Create entangled state first + stn.h(&[QubitId(0)]); + dsv.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + dsv.cx(&[(QubitId(0), QubitId(1))]); + stn.h(&[QubitId(2)]); + dsv.h(&[QubitId(2)]); + + // Apply RZZ at Clifford angle + let pairs = [(QubitId(0), QubitId(1))]; + stn.rzz(angle, &pairs); + dsv.rzz(angle, &pairs); + + // Bond dim should stay 1 (Clifford doesn't grow MPS) + assert_eq!( + stn.max_bond_dim(), + 1, + "RZZ({angle:?}) should not grow bond dim" + ); + + let stn_sv = stn.state_vector(); + let ref_sv: Vec = (0..8).map(|i| dsv.get_amplitude(i)).collect(); + assert_states_match(&stn_sv, &ref_sv, &format!("RZZ Clifford angle {angle:?}")); + } +} + +#[test] +fn test_rzz_then_non_clifford() { + // RZZ at non-Clifford angle, then more gates. Verify state. + let angle = Angle64::from_radians(0.7); + let t = Angle64::QUARTER_TURN / 2u64; + + let mut stn = StabMps::with_seed(3, 42); + let mut dsv = pecos_simulators::DenseStateVec::new(3); + + stn.h(&[QubitId(0)]); + dsv.h(&[QubitId(0)]); + stn.h(&[QubitId(1)]); + dsv.h(&[QubitId(1)]); + stn.rzz(angle, &[(QubitId(0), QubitId(1))]); + dsv.rzz(angle, &[(QubitId(0), QubitId(1))]); + stn.rz(t, &[QubitId(0)]); + dsv.rz(t, &[QubitId(0)]); + stn.cx(&[(QubitId(1), QubitId(2))]); + dsv.cx(&[(QubitId(1), QubitId(2))]); + stn.rz(t, &[QubitId(2)]); + dsv.rz(t, &[QubitId(2)]); + + let stn_sv = stn.state_vector(); + let ref_sv: Vec = (0..8).map(|i| dsv.get_amplitude(i)).collect(); + assert_states_close(&stn_sv, &ref_sv, 0.05, "RZZ then non-Clifford"); +} + +// ============================================================================ +// compress() correctness +// ============================================================================ + +#[test] +fn test_compress_preserves_state() { + use pecos_stab_tn::mps::{Mps, MpsConfig}; + + // Build an MPS via addition (doubles bond dim), then compress. + // State vector should be unchanged. + let mps_a = Mps::new(3, MpsConfig::default()); + let mut mps_b = Mps::new(3, MpsConfig::default()); + + let h = nalgebra::DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(std::f64::consts::FRAC_1_SQRT_2, 0.0), + Complex64::new(-std::f64::consts::FRAC_1_SQRT_2, 0.0), + ], + ); + let cnot = nalgebra::DMatrix::from_row_slice( + 4, + 4, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + + // mps_a = |000> + // mps_b = H(0) CX(0,1) |000> = Bell on (0,1) ⊗ |0> + mps_b.apply_one_site_gate(0, &h).unwrap(); + mps_b.apply_two_site_gate(0, &cnot).unwrap(); + mps_b.scale(Complex64::new(0.5, 0.0)); // scale down + + let sum = mps_a.add(&mps_b); + let sv_before = sum.state_vector(); + let bond_before = sum.max_bond_dim(); + + let mut compressed = sum; + compressed.compress(); + let sv_after = compressed.state_vector(); + let bond_after = compressed.max_bond_dim(); + + // State should be preserved + assert_eq!(sv_before.len(), sv_after.len()); + for (i, (a, b)) in sv_before.iter().zip(sv_after.iter()).enumerate() { + assert!( + (a - b).norm() < 1e-10, + "compress changed amplitude at index {i}: {a:.6} -> {b:.6}" + ); + } + + // Bond dim should not increase + assert!( + bond_after <= bond_before, + "compress increased bond dim: {bond_before} -> {bond_after}" + ); +} + +// ============================================================================ +// MAST 3-qubit measurement investigation +// ============================================================================ + +#[test] +fn test_mast_single_t_measurement_distribution() { + // Simpler MAST test: H(0), T(0), measure. p(0)=p(1)=0.5. + let t = Angle64::QUARTER_TURN / 2u64; + let num_trials = 500; + let mut count_0 = 0u32; + + for trial in 0..num_trials { + let mut mast = Mast::with_seed(1, 2, 10000 + trial as u64); + mast.h(&[QubitId(0)]); + mast.rz(t, &[QubitId(0)]); + if !mast.mz(&[QubitId(0)])[0].outcome { + count_0 += 1; + } + } + let p0 = f64::from(count_0) / f64::from(num_trials); + assert!( + (p0 - 0.5).abs() < 0.1, + "MAST T|+> measurement: p(0)={p0:.3}, expected 0.5" + ); +} + +#[test] +fn test_mast_bell_t_measurement_correlation() { + // MAST: Bell + T, measure both. Outcomes should be correlated. + let t = Angle64::QUARTER_TURN / 2u64; + let num_trials = 200; + let mut correlated = 0u32; + + for trial in 0..num_trials { + let mut mast = Mast::with_seed(2, 2, 11000 + trial as u64); + mast.h(&[QubitId(0)]); + mast.cx(&[(QubitId(0), QubitId(1))]); + mast.rz(t, &[QubitId(0)]); + + let r0 = mast.mz(&[QubitId(0)])[0].outcome; + let r1 = mast.mz(&[QubitId(1)])[0].outcome; + if r0 == r1 { + correlated += 1; + } + } + let corr_rate = f64::from(correlated) / f64::from(num_trials); + // Bell state: outcomes should be perfectly correlated + assert!( + corr_rate > 0.95, + "MAST Bell+T correlation: {corr_rate:.3}, expected ~1.0" + ); +} + +#[test] +fn test_mast_3qubit_outcome_coverage() { + // Check that MAST produces multiple distinct outcomes for a 3-qubit circuit. + let t = Angle64::QUARTER_TURN / 2u64; + let num_trials = 300; + let mut seen = std::collections::HashSet::new(); + + for trial in 0..num_trials { + let mut mast = Mast::with_seed(3, 4, 12000 + trial as u64); + mast.h(&[QubitId(0)]); + mast.h(&[QubitId(1)]); + mast.h(&[QubitId(2)]); + mast.rz(t, &[QubitId(0)]); + mast.cx(&[(QubitId(0), QubitId(1))]); + mast.rz(t, &[QubitId(1)]); + + let results = mast.mz(&[QubitId(0), QubitId(1), QubitId(2)]); + let outcome: u8 = results + .iter() + .enumerate() + .map(|(i, r)| (u8::from(r.outcome)) << i) + .sum(); + seen.insert(outcome); + } + + // With H on all qubits + T + entangling, we should see many outcomes + assert!( + seen.len() >= 4, + "MAST 3q should produce at least 4 distinct outcomes, got {}", + seen.len() + ); +} + +// ============================================================================ +// Paper property verification +// ============================================================================ + +#[test] +fn test_property_cliffords_dont_grow_bond_dim() { + // Paper claim: Clifford gates only update the tableau. MPS stays at bond dim 1. + let mut stn = StabMps::with_seed(8, 42); + + // Apply many Clifford gates: H, S, CX, CZ on all qubits + for q in 0..8 { + stn.h(&[QubitId(q)]); + } + for q in 0..7 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + for q in 0..8 { + stn.sz(&[QubitId(q)]); + } + for q in (0..7).rev() { + stn.cz(&[(QubitId(q), QubitId(q + 1))]); + } + for q in 0..8 { + stn.h(&[QubitId(q)]); + } + + // Bond dim should still be 1 everywhere + assert_eq!( + stn.max_bond_dim(), + 1, + "Clifford gates should not grow bond dimension" + ); +} + +#[test] +fn test_property_stn_bond_dim_grows_with_nonclifford() { + // Paper claim: each non-Clifford gate on an entangled state can increase bond dim. + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::with_seed(4, 42); + + // Create entangled state + for q in 0..4 { + stn.h(&[QubitId(q)]); + } + for q in 0..3 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + + let bond_before = stn.max_bond_dim(); + assert_eq!(bond_before, 1, "pure Clifford should have bond dim 1"); + + // Apply T gates — bond dim should grow + stn.rz(t, &[QubitId(0)]); + let bond_after_1t = stn.max_bond_dim(); + assert!( + bond_after_1t >= 1, + "T gate on entangled state should maintain or grow bond dim" + ); + + stn.rz(t, &[QubitId(2)]); + let bond_after_2t = stn.max_bond_dim(); + + eprintln!( + "STN bond dim: before={bond_before}, after 1T={bond_after_1t}, after 2T={bond_after_2t}" + ); +} + +#[test] +fn test_property_mast_bond_dim_stays_low() { + // Paper claim (PRL 2025): for random circuits with t <= N non-Clifford gates, + // MAST bond dimension stays ~3 on average. + let t = Angle64::QUARTER_TURN / 2u64; + let num_qubits = 8; + let num_t_gates = 8; // t = N + + let mut total_max_bond = 0usize; + let num_trials = 20; + + for trial in 0..num_trials { + let mut mast = Mast::with_seed(num_qubits, num_t_gates, 20000 + trial as u64); + + // Random Clifford layer + for q in 0..num_qubits { + mast.h(&[QubitId(q)]); + } + for q in 0..num_qubits - 1 { + mast.cx(&[(QubitId(q), QubitId(q + 1))]); + } + + // Apply t T gates on random qubits + let mut rng_state = 30000 + trial as u64; + for _ in 0..num_t_gates { + rng_state ^= rng_state << 13; + rng_state ^= rng_state >> 7; + rng_state ^= rng_state << 17; + let q = (rng_state % num_qubits as u64) as usize; + mast.rz(t, &[QubitId(q)]); + } + + // More Clifford entangling + for q in (0..num_qubits - 1).rev() { + mast.cx(&[(QubitId(q + 1), QubitId(q))]); + } + + // Force projection of all deferred measurements + mast.mz(&[QubitId(0)]); + + total_max_bond += mast.mps().max_bond_dim(); + } + + let avg_bond = total_max_bond as f64 / f64::from(num_trials); + eprintln!("MAST average max bond dim for {num_qubits}q, {num_t_gates}T: {avg_bond:.1}"); + + // Paper claims ~3 for t <= N. Allow some slack for our small test. + assert!( + avg_bond < 10.0, + "MAST bond dim should stay low for t <= N, got avg={avg_bond:.1}" + ); +} + +#[test] +fn test_property_mast_vs_stn_bond_dim() { + // Paper claim: MAST has lower bond dimension than plain STN for the same circuit. + let t = Angle64::QUARTER_TURN / 2u64; + let num_qubits = 6; + + let mut stn = StabMps::with_seed(num_qubits, 42); + let mut mast = Mast::with_seed(num_qubits, 4, 42); + + // Same circuit on both + for q in 0..num_qubits { + stn.h(&[QubitId(q)]); + mast.h(&[QubitId(q)]); + } + for q in 0..num_qubits - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + mast.cx(&[(QubitId(q), QubitId(q + 1))]); + } + for q in 0..4 { + stn.rz(t, &[QubitId(q)]); + mast.rz(t, &[QubitId(q)]); + } + + // Force MAST projection + mast.mz(&[QubitId(0)]); + + let stn_bond = stn.max_bond_dim(); + let mast_bond = mast.mps().max_bond_dim(); + + eprintln!("STN max bond: {stn_bond}, MAST max bond: {mast_bond}"); + + // MAST should generally have lower or equal bond dim + // (not always guaranteed for small circuits, so just log it) +} + +#[test] +fn test_property_disentangle_reduces_bond_dim() { + // Paper claim: Clifford disentangling can reduce MPS bond dimension. + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::with_seed(3, 42); + + stn.h(&[QubitId(0)]); + stn.cx(&[(QubitId(0), QubitId(1))]); + stn.rz(t, &[QubitId(0)]); + stn.h(&[QubitId(2)]); + stn.cx(&[(QubitId(1), QubitId(2))]); + stn.rz(t, &[QubitId(2)]); + + let bond_before = stn.max_bond_dim(); + let sv_before = stn.state_vector(); + + let num_gates = stn.disentangle(5); + + let bond_after = stn.max_bond_dim(); + let sv_after = stn.state_vector(); + + eprintln!("Disentangle: bond {bond_before} -> {bond_after}, applied {num_gates} gates"); + + // State should be preserved + assert_states_match(&sv_before, &sv_after, "disentangle preserves state"); + + // Bond dim should not increase (and ideally decreases) + assert!( + bond_after <= bond_before, + "disentangle should not increase bond dim: {bond_before} -> {bond_after}" + ); +} + +// ============================================================================ +// Large-scale bond dimension validation +// ============================================================================ + +/// Run a random circuit on STN/MAST at scale. No state vector check (too large). +/// Just verify bond dim stays bounded and measurements work. +fn large_scale_bond_dim_check( + num_qubits: usize, + num_t_gates: usize, + num_clifford_layers: usize, + seed: u64, +) -> (usize, usize) { + // STN path + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::builder(num_qubits) + .max_bond_dim(256) + .seed(seed) + .build(); + + let mut rng = seed; + let next = |state: &mut u64| -> u64 { + *state ^= *state << 13; + *state ^= *state >> 7; + *state ^= *state << 17; + *state + }; + + // Alternating Clifford + T layers + let t_per_layer = num_t_gates / num_clifford_layers.max(1); + for _layer in 0..num_clifford_layers { + // Random Clifford entangling layer + for q in 0..num_qubits { + if next(&mut rng) % 2 == 0 { + stn.h(&[QubitId(q)]); + } + } + for q in 0..num_qubits - 1 { + if next(&mut rng) % 3 == 0 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + } + // T gates on random qubits + for _ in 0..t_per_layer { + let q = (next(&mut rng) % num_qubits as u64) as usize; + stn.rz(t, &[QubitId(q)]); + } + } + + let stn_bond = stn.max_bond_dim(); + + // MAST path (same circuit structure) + let mut mast = Mast::with_seed(num_qubits, num_t_gates + 4, seed); + let mut rng = seed; // reset RNG to get same circuit + + for _layer in 0..num_clifford_layers { + for q in 0..num_qubits { + if next(&mut rng) % 2 == 0 { + mast.h(&[QubitId(q)]); + } + } + for q in 0..num_qubits - 1 { + if next(&mut rng) % 3 == 0 { + mast.cx(&[(QubitId(q), QubitId(q + 1))]); + } + } + for _ in 0..t_per_layer { + let q = (next(&mut rng) % num_qubits as u64) as usize; + mast.rz(t, &[QubitId(q)]); + } + } + + // Force MAST projection + mast.mz(&[QubitId(0)]); + let mast_bond = mast.mps().max_bond_dim(); + + (stn_bond, mast_bond) +} + +#[test] +fn test_large_scale_50_qubits() { + let num_qubits = 50; + let num_t = 20; + let (stn_bond, mast_bond) = large_scale_bond_dim_check(num_qubits, num_t, 4, 42); + eprintln!("{num_qubits}q {num_t}T: STN bond={stn_bond}, MAST bond={mast_bond}"); + // Should complete without panic. MAST bond should be small. + assert!( + mast_bond < 50, + "MAST bond too large at {num_qubits}q: {mast_bond}" + ); +} + +#[test] +fn test_large_scale_100_qubits() { + let num_qubits = 100; + let num_t = 40; + let (stn_bond, mast_bond) = large_scale_bond_dim_check(num_qubits, num_t, 4, 123); + eprintln!("{num_qubits}q {num_t}T: STN bond={stn_bond}, MAST bond={mast_bond}"); + assert!( + mast_bond < 50, + "MAST bond too large at {num_qubits}q: {mast_bond}" + ); +} + +#[test] +fn test_large_scale_200_qubits() { + let num_qubits = 200; + let num_t = 50; + let (stn_bond, mast_bond) = large_scale_bond_dim_check(num_qubits, num_t, 5, 456); + eprintln!("{num_qubits}q {num_t}T: STN bond={stn_bond}, MAST bond={mast_bond}"); + assert!( + mast_bond < 50, + "MAST bond too large at {num_qubits}q: {mast_bond}" + ); +} + +#[test] +#[ignore = "slow (~3min debug): run with `cargo test --test verification -- --include-ignored`"] +fn test_large_scale_bond_dim_curve() { + // Track bond dim as a function of T-count for fixed qubit count. + let num_qubits = 50; + let t_counts = [5, 10, 20, 30, 40, 50]; + + eprintln!("\nBond dim curve for {num_qubits} qubits:"); + eprintln!(" T-count STN-bond MAST-bond"); + for &num_t in &t_counts { + let (stn_bond, mast_bond) = large_scale_bond_dim_check(num_qubits, num_t, 4, 789); + eprintln!(" {num_t:>7} {stn_bond:>8} {mast_bond:>9}"); + } +} + +#[test] +fn test_large_scale_measurement_works() { + // Verify measurement doesn't panic at 30 qubits. + let num_qubits = 30; + let t = Angle64::QUARTER_TURN / 2u64; + let mut stn = StabMps::with_seed(num_qubits, 42); + + // Build entangled state + for q in 0..num_qubits { + stn.h(&[QubitId(q)]); + } + for q in 0..num_qubits - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + // Apply some T gates + for q in (0..num_qubits).step_by(5) { + stn.rz(t, &[QubitId(q)]); + } + + // Measure a subset of qubits (measuring all 100 is too slow) + let measure_qubits: Vec = (0..10).map(QubitId).collect(); + let results = stn.mz(&measure_qubits); + assert_eq!(results.len(), 10); + + eprintln!( + "{num_qubits}q measurement: bond_dim={}, measured 10 of {num_qubits} qubits", + stn.max_bond_dim() + ); +} + +// ============================================================================ +// Shared measurement stress test suite +// ============================================================================ + +pecos_simulators::measurement_stress_test_suite!(StabMps, 4, StabMps::with_seed(4, 42)); + +// ============================================================================ +// Performance profiling (run with --nocapture to see timing) +// ============================================================================ + +#[test] +fn test_profile_operation_costs() { + use std::time::Instant; + let t = Angle64::QUARTER_TURN / 2u64; + + for &num_qubits in &[20, 50, 100, 200] { + let mut stn = StabMps::builder(num_qubits).seed(42).build(); + + // Clifford layer: H + CX chain + let start = Instant::now(); + for q in 0..num_qubits { + stn.h(&[QubitId(q)]); + } + for q in 0..num_qubits - 1 { + stn.cx(&[(QubitId(q), QubitId(q + 1))]); + } + let clifford_ms = start.elapsed().as_millis(); + + // T gates + let num_t = num_qubits / 4; + let start = Instant::now(); + for q in 0..num_t { + stn.rz(t, &[QubitId(q)]); + } + let t_ms = start.elapsed().as_millis(); + + // Second Clifford layer + let start = Instant::now(); + for q in (0..num_qubits - 1).rev() { + stn.cx(&[(QubitId(q + 1), QubitId(q))]); + } + for q in 0..num_qubits { + stn.h(&[QubitId(q)]); + } + let clifford2_ms = start.elapsed().as_millis(); + + eprintln!( + "{num_qubits:>3}q: clifford1={clifford_ms:>4}ms, {num_t}T={t_ms:>4}ms, clifford2={clifford2_ms:>4}ms, bond={}", + stn.max_bond_dim() + ); + } +} diff --git a/mkdocs.yml b/mkdocs.yml index 83e86102d..2d930b036 100644 --- a/mkdocs.yml +++ b/mkdocs.yml @@ -55,10 +55,17 @@ nav: - WASM Foreign Objects: user-guide/wasm-foreign-objects.md - HUGR & Guppy Simulation: user-guide/hugr-simulation.md - Simulators: user-guide/simulators.md + - Engine Selection: user-guide/engine-selection.md - Gate Reference: user-guide/gates.md - Gate Naming Conventions: user-guide/gate-naming-conventions.md - Gate Naming (Future): user-guide/gate-naming-speculation.md + - Gate and Angle Types: user-guide/gate-angle-types.md - Noise Model Builders: user-guide/noise-model-builders.md + - Quantum Operator Algebra: user-guide/quantum-operator-algebra.md + - Stabilizer Codes: user-guide/stabilizer-codes.md + - Pauli Algebra and QEC in Python: user-guide/python-pauli-qec.md + - Fault Tolerance Analysis: user-guide/fault-tolerance.md + - Fault Catalog Tutorial: user-guide/fault-catalog.md - QEC Geometry: user-guide/qec-geometry.md - QEC with Guppy: user-guide/qec-guppy.md - Decoders: user-guide/decoders.md @@ -69,7 +76,7 @@ nav: - CUDA Setup: user-guide/cuda-setup.md - Concepts: - concepts/index.md - - Clifford+RZ Simulator: concepts/clifford-rz-simulator.md + - StabVec Simulator: concepts/clifford-rz-simulator.md - API: - api/api-reference.md - Development: @@ -77,9 +84,14 @@ nav: - Developer Tools CLI: development/dev-tools.md - Documentation Testing: development/doc-testing.md - SLR and QECLib: development/slr-qeclib.md - - Circuit Representations: development/circuit-representations.md + - AST Infrastructure: development/ast-infrastructure.md + - Foreign Language Plugins: development/foreign-plugins.md - Parallel Blocks: development/parallel-blocks-and-optimization.md - - development/QIS_ARCHITECTURE.md +- Experimental: + - experimental/index.md + - Composable Noise (pecos-neo): experimental/composable-noise.md +- Proposals: + - proposals/README.md - Releases: - releases/changelog.md markdown_extensions: @@ -126,4 +138,4 @@ extra: link: https://pypi.org/project/quantum-pecos/ - icon: fontawesome/solid/book link: https://quantum-pecos.readthedocs.io/ -copyright: Copyright © 2018-2025 The PECOS Developers +copyright: Copyright © 2018-2026 The PECOS Developers diff --git a/pyproject.toml b/pyproject.toml index 7d7593085..6228d25b1 100644 --- a/pyproject.toml +++ b/pyproject.toml @@ -1,10 +1,9 @@ [project] name = "pecos-workspace" version = "0.8.0.dev5" -# Development dependencies that are optional in quantum-pecos but needed for full dev/test -dependencies = [ - "stim>=1.15.0", # Optional in quantum-pecos, but needed for stim-related tests -] +# Meta-package; runtime deps live in the member packages. Test/example/dev +# tooling is declared in [dependency-groups] below. +dependencies = [] [project.optional-dependencies] cuda = ["quantum-pecos[cuda]"] @@ -12,20 +11,27 @@ cuda = ["quantum-pecos[cuda]"] [tool.uv.workspace] members = [ "python/pecos-rslib", + "python/pecos-rslib-exp", "python/pecos-rslib-cuda", "python/pecos-rslib-llvm", "python/quantum-pecos", - "python/selene-plugins/pecos-selene-*", + "python/selene-plugins/pecos-selene-mast", + "python/selene-plugins/pecos-selene-stab-mps", + "python/selene-plugins/pecos-selene-stab-vec", + "python/selene-plugins/pecos-selene-stabilizer", + "python/selene-plugins/pecos-selene-statevec", ] [tool.uv.sources] quantum-pecos = { workspace = true } [dependency-groups] +# Build, lint, and docs tooling. Runtime deps used by member packages +# (networkx, matplotlib, phir, ...) come in transitively via quantum-pecos. dev = [ - "maturin>=1.13.1,<2.0", # For building (should match build requirements) + "maturin>=1.13.1,<2.0", # For building (matches sub-package build-system requirements) "patchelf; platform_system != 'Windows'", # For setting rpath in shared libraries (Linux/macOS only) - "setuptools>=82.0.1", # Build system + "setuptools>=82.0.1", # Build system "pre-commit", # Git hooks "black", # Code formatting "ruff", # Fast Python linting @@ -33,20 +39,25 @@ dev = [ "mkdocs-material", # Material theme for MkDocs "mkdocstrings[python]", # Code documentation extraction "markdown-exec[ansi]", # Executable markdown blocks - # Runtime dependencies for development (non-test) - "networkx>=2.1.0", - "matplotlib>=2.2.0", - "phir>=0.3.3", - "polars>=1.0.0", # DataFrame library for examples/benchmarks - # WebAssembly runtimes for testing - "wasmtime>=43.0.0", - "jupyter>=1.1.1", ] -test = [ # pinning testing environment - "pytest==8.3.3", # 8.3.4 seems to be causing errors - "pytest-cov==6.0.0", - "pytest-timeout>=2.3.1", - "hypothesis==6.122.3", +test = [ # exact pins so workspace tests run against a reproducible environment + # Note: sub-package test extras (pecos-rslib, selene plugins) intentionally + # use `pytest>=9.0` lower bounds instead of these exact pins -- those + # packages ship to PyPI and must stay installable against newer pytest + # releases that downstream users may already have. Reproducibility for + # in-repo dev comes from uv.lock, not from over-constraining the sub-package + # requires-dist. + "pytest==9.0.3", + "pytest-cov==7.1.0", + "pytest-timeout==2.4.0", + "hypothesis==6.152.1", + "stim==1.15.0", # Stim-comparison and decomposition-invariant tests + "wasmtime==43.0.0", # WebAssembly runtime exercised by integration tests + "matplotlib>=2.2.0", # Surface-patch render tests import matplotlib directly +] +examples = [ # extras used by the examples/ tree and notebook walkthroughs + "jupyter>=1.1.1", + "polars>=1.0.0", ] numpy-compat = [ # NumPy/SciPy compatibility tests - verify compatibility with scientific Python stack "numpy>=1.15.0", @@ -70,7 +81,6 @@ line-length = 120 markers = [ "optional_dependency: mark a test as using one or more optional dependencies", "optional_unix: mark tests as using an optional dependency that only work with Unix-based systems", - "wasmer: mark test as using the 'wasmer' option", - "wasmtime: mark test as using the 'wasmtime' option", + "slow: mark tests that provide extra integration coverage but are excluded from the default fast Python test lane", "numpy: mark tests that verify NumPy compatibility (requires numpy installed)", ] diff --git a/python/pecos-rslib-cuda/pyproject.toml b/python/pecos-rslib-cuda/pyproject.toml index 60fb1a258..3e96e850b 100644 --- a/python/pecos-rslib-cuda/pyproject.toml +++ b/python/pecos-rslib-cuda/pyproject.toml @@ -31,7 +31,7 @@ classifiers = [ ] [build-system] -requires = ["maturin>=1.2,<2.0"] +requires = ["maturin>=1.13.1,<2.0"] build-backend = "maturin" [tool.maturin] @@ -40,7 +40,7 @@ module-name = "pecos_rslib_cuda" [dependency-groups] dev = [] test = [ - 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You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Coherent idle noise channel: RZ(angle) on both qubits after each CX gate. + +use pecos_core::Angle64; +use pecos_neo::command::{GateCommand, GateType}; +use pecos_neo::noise::{NoiseChannel, NoiseContext, NoiseEvent, NoiseResponse}; +use pecos_random::PecosRng; +use smallvec::SmallVec; + +/// Applies coherent RZ rotation after each two-qubit gate on both qubits. +/// +/// Models uncompensated phase accumulation during idle time between gates. +/// The rotation angle represents the coherent Z-phase acquired per gate +/// application. +#[derive(Clone)] +pub struct CoherentIdleChannel { + angle: Angle64, +} + +impl CoherentIdleChannel { + /// Create a coherent idle channel with the given RZ angle (radians). + pub fn new(angle_radians: f64) -> Self { + Self { + angle: Angle64::from_radians(angle_radians), + } + } +} + +impl NoiseChannel for CoherentIdleChannel { + fn responds_to(&self, event: &NoiseEvent<'_>) -> bool { + matches!( + event, + NoiseEvent::AfterGate { + gate_type: GateType::CX | GateType::CZ | GateType::CY, + .. + } + ) + } + + fn apply( + &self, + event: &NoiseEvent<'_>, + _ctx: &mut NoiseContext, + _rng: &mut PecosRng, + ) -> NoiseResponse { + if let NoiseEvent::AfterGate { qubits, .. } = event { + let mut gates = SmallVec::new(); + for &q in *qubits { + gates.push(GateCommand::rz(q, self.angle)); + } + NoiseResponse::inject_gates(gates) + } else { + NoiseResponse::None + } + } + + fn name(&self) -> &'static str { + "CoherentIdleRZ" + } + + fn clone_box(&self) -> Box { + Box::new(self.clone()) + } +} diff --git a/python/pecos-rslib-exp/src/eeg_bindings.rs b/python/pecos-rslib-exp/src/eeg_bindings.rs new file mode 100644 index 000000000..f40eaca7a --- /dev/null +++ b/python/pecos-rslib-exp/src/eeg_bindings.rs @@ -0,0 +1,1396 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 + +//! Python bindings for EEG DEM builder. + +use pecos_core::pauli::pauli_bitmask::BitmaskStorage; +use pecos_core::{Angle64, Gate, GateAngles, GateMeasIds, GateParams, GateQubits, QubitId}; +use pecos_eeg::Bm; +use pecos_eeg::circuit::{self, NoiseModel}; +use pecos_eeg::dem_mapping::{DemEntry, Detector, Observable}; +use pyo3::prelude::*; + +/// Build a DEM using forward EEG analysis (perturbative, fast). +/// +/// Returns (raw_dem, decomposed_dem) where the decomposed version uses +/// X/Z Pauli-aware decomposition for MWPM decoders. +/// +/// Fast (milliseconds) but approximate (~50% error for coherent noise). +/// For exact probabilities, use `coherent_dem_decomposed`. +/// +/// h_formula: "taylor" (default), "sin_squared", "exact_commuting", or "exact_subset" +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0, h_formula="taylor", bch_order=1))] +pub fn perturbative_dem( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + h_formula: &str, + bch_order: u32, +) -> PyResult<(String, String)> { + let (raw, decomposable) = run_eeg_decomposable( + tick_circuit, + idle_rz, + p1, + p2, + p_meas, + p_prep, + h_formula, + bch_order, + )?; + Ok(( + pecos_eeg::dem_mapping::format_dem(&raw), + pecos_eeg::dem_mapping::format_dem_decomposed(&decomposable), + )) +} + +/// Build perturbative DEM and return structured events: list of (prob, [det_ids], [obs_ids]). +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0, h_formula="taylor", bch_order=1))] +pub fn perturbative_dem_events( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + h_formula: &str, + bch_order: u32, +) -> PyResult, Vec)>> { + let entries = run_eeg( + tick_circuit, + idle_rz, + p1, + p2, + p_meas, + p_prep, + h_formula, + bch_order, + )?; + Ok(entries + .into_iter() + .map(|e| { + ( + e.probability, + e.event.detectors.to_vec(), + e.event.observables.to_vec(), + ) + }) + .collect()) +} + +/// Return (num_h_generators, num_s_generators, num_detectors, numobservables). +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0))] +pub fn eeg_summary( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, +) -> PyResult<(usize, usize, usize, usize)> { + let noise = NoiseModel { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(tick_circuit)?; + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let result = circuit::analyze_expanded(&expanded.gates, &noise); + let (detectors, observables) = extract_detectors_expanded(tick_circuit, &expanded)?; + let h = result + .generators + .iter() + .filter(|g| g.eeg_type == pecos_eeg::eeg::EegType::H) + .count(); + let s = result + .generators + .iter() + .filter(|g| g.eeg_type == pecos_eeg::eeg::EegType::S) + .count(); + Ok((h, s, detectors.len(), observables.len())) +} + +/// Diagnostic: for each DEM event, return generator details. +/// +/// Returns list of (det_ids, num_labels, num_same_label_groups, rates_by_label, max_combined_rate) +/// This helps understand why perturbative formulas are inaccurate. +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0))] +pub fn eeg_event_diagnostics( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, +) -> PyResult, usize, usize, Vec, f64)>> { + let noise = NoiseModel { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(tick_circuit)?; + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let result = circuit::analyze_expanded(&expanded.gates, &noise); + let (detectors, _observables) = extract_detectors_expanded(tick_circuit, &expanded)?; + + use pecos_eeg::eeg::EegType; + use std::collections::BTreeMap; + + // Group H generators by DEM event, tracking labels + let mut h_events: BTreeMap, BTreeMap> = BTreeMap::new(); + + for g in &result.generators { + if g.eeg_type != EegType::H { + continue; + } + // Classify manually + let mut dets = Vec::new(); + for det in &detectors { + if !g.label.commutes_with(&det.stabilizer) { + dets.push(det.id); + } + } + if dets.is_empty() { + continue; + } + *h_events + .entry(dets) + .or_default() + .entry(g.label.clone()) + .or_insert(0.0) += g.coeff; + } + + let mut out = Vec::new(); + for (det_ids, labels) in &h_events { + let num_labels = labels.len(); + let rates: Vec = labels.values().copied().collect(); + let num_groups = rates.iter().filter(|&&r| r.abs() > 1e-15).count(); + let max_combined = rates.iter().map(|r| r.abs()).fold(0.0_f64, f64::max); + out.push((det_ids.clone(), num_labels, num_groups, rates, max_combined)); + } + Ok(out) +} + +/// Compute per-detector marginals using ALL generators that flip each detector. +/// +/// Unlike the DEM-based approach (which groups by event then sums), this pools +/// all H generators for each detector into a single quadratic form with beta +/// cross-terms. This captures cross-event interference that the per-event +/// computation misses. +/// +/// Returns list of (detector_id, probability). +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0, h_formula="taylor"))] +pub fn eeg_per_detector( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + h_formula: &str, +) -> PyResult> { + let noise = NoiseModel { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(tick_circuit)?; + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let result = circuit::analyze_expanded(&expanded.gates, &noise); + let (detectors, _observables) = extract_detectors_expanded(tick_circuit, &expanded)?; + + let expanded_pre_readout = exclude_final_mz(&expanded.gates); + let stab_group = pecos_eeg::stabilizer::StabilizerGroup::from_circuit( + &expanded_pre_readout, + expanded.num_qubits, + ); + + let formula = parse_h_formula(h_formula)?; + + // Collect all H generators with their BCH-combined rates per label + let mut h_by_label: std::collections::BTreeMap = std::collections::BTreeMap::new(); + for g in &result.generators { + if g.eeg_type == pecos_eeg::eeg::EegType::H { + *h_by_label.entry(g.label.clone()).or_insert(0.0) += g.coeff; + } + } + let h_labels: Vec<(Bm, f64)> = h_by_label + .into_iter() + .filter(|(_, c)| c.abs() > 1e-20) + .collect(); + + // Also collect S generators + let mut s_by_label: std::collections::BTreeMap = std::collections::BTreeMap::new(); + for g in &result.generators { + if g.eeg_type == pecos_eeg::eeg::EegType::S { + *s_by_label.entry(g.label.clone()).or_insert(0.0) += g.coeff; + } + } + + let mut results = Vec::new(); + + for det in &detectors { + // Find all H generators that anticommute with this detector + let det_h: Vec<(usize, f64)> = h_labels + .iter() + .enumerate() + .filter(|(_, (label, _))| !label.commutes_with(&det.stabilizer)) + .map(|(i, (_, c))| (i, *c)) + .collect(); + + // Find S generators that anticommute + let s_sum: f64 = s_by_label + .iter() + .filter(|(label, _)| !label.commutes_with(&det.stabilizer)) + .map(|(_, c)| c) + .sum(); + + // S contribution + let p_s = if s_sum.abs() > 1e-20 { + (1.0 - (2.0 * s_sum).exp()) / 2.0 + } else { + 0.0 + }; + + // H contribution: quadratic form with beta + let n = det_h.len(); + let h_prob = match formula { + pecos_eeg::dem_mapping::HFormula::Taylor + | pecos_eeg::dem_mapping::HFormula::SinSquared + | pecos_eeg::dem_mapping::HFormula::ExactSubset => { + let mut total = 0.0_f64; + for j in 0..n { + let (idx_j, h_j) = det_h[j]; + // Diagonal + total += h_j * h_j; + // Off-diagonal with beta + for k in (j + 1)..n { + let (idx_k, h_k) = det_h[k]; + let q_j = &h_labels[idx_j].0; + let q_k = &h_labels[idx_k].0; + + if !q_j.commutes_with(q_k) { + continue; + } + let product = q_j.multiply(q_k); + if product.is_identity() { + total += 2.0 * h_j * h_k; + continue; + } + match stab_group.is_stabilizer(&product) { + Some(true) => { + total += 2.0 * h_j * h_k; + } + Some(false) => { + total -= 2.0 * h_j * h_k; + } + None => {} + } + } + } + let total = total.max(0.0); + match formula { + pecos_eeg::dem_mapping::HFormula::SinSquared => total.sqrt().sin().powi(2), + _ => total, + } + } + pecos_eeg::dem_mapping::HFormula::ExactCommuting => { + // Product formula over all generators for this detector + let mut prod_re = 1.0_f64; + let mut prod_im = 0.0_f64; + for &(idx_j, h_j) in &det_h { + let label = &h_labels[idx_j].0; + let p_stab = if label.is_identity() { + Some(true) + } else { + stab_group.is_stabilizer(label) + }; + + let (f_re, f_im) = if let Some(sign) = p_stab { + let s = if sign { 1.0 } else { -1.0 }; + let angle = 2.0 * s * h_j; + (angle.cos(), angle.sin()) + } else { + let dp = det.stabilizer.multiply(label); + let dp_stab = if dp.is_identity() { + Some(true) + } else { + stab_group.is_stabilizer(&dp) + }; + if let Some(sign) = dp_stab { + let s = if sign { 1.0 } else { -1.0 }; + let angle = -2.0 * s * h_j; + (angle.cos(), angle.sin()) + } else { + ((2.0 * h_j).cos(), 0.0) + } + }; + let new_re = prod_re * f_re - prod_im * f_im; + let new_im = prod_re * f_im + prod_im * f_re; + prod_re = new_re; + prod_im = new_im; + } + (0.5 * (1.0 - prod_re)).max(0.0) + } + }; + + // Combine S and H (independent) + let p = if p_s.abs() > 1e-15 && h_prob > 1e-15 { + p_s + h_prob - 2.0 * p_s * h_prob + } else { + p_s.abs() + h_prob + }; + results.push((det.id, p)); + } + + Ok(results) +} + +/// Compute exact per-detector detection probabilities. +/// +/// Uses backward Heisenberg propagation: walks the detector observable +/// backward through the circuit, splitting at each noise source. Exact +/// for both coherent (idle_rz) and stochastic (depolarizing) noise. +/// +/// This is the most accurate DEM generation method in PECOS. Use it when: +/// - You need exact detection rates under coherent noise +/// - You want to validate the non-EEG DEM builder +/// - You need per-detector probabilities (not a full DEM) +/// +/// For a full DEM (event structure + probabilities), use `eeg_heisenberg_dem`. +/// For fast approximate rates under coherent noise, use `eeg_dem_events`. +/// For depolarizing-only noise, `DemSampler.from_circuit` is faster and exact. +/// +/// Returns: list of (detector_id, probability) for each detector. +/// +/// Example: +/// probs = exact_detection_rates(tc, idle_rz=0.05) +/// probs = exact_detection_rates(tc, idle_rz=0.05, p2=0.01) +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0, prune=1e-12, window=None))] +pub fn exact_detection_rates( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + prune: f64, + #[allow(unused_variables)] window: Option, +) -> PyResult> { + let noise = pecos_eeg::noise::UniformNoise { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(tick_circuit)?; + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let (detectors, _observables) = extract_detectors_expanded(tick_circuit, &expanded)?; + + // Build initial stabilizer group: Z on each original qubit + let init_gates: Vec = (0..expanded.num_original_qubits) + .map(|q| pecos_eeg::expand::make_gate(pecos_core::gate_type::GateType::PZ, &[q])) + .collect(); + let stab = + pecos_eeg::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); + + // Build qubit-to-gate index once, shared across all detector walks. + let gate_index = pecos_eeg::expand::GateIndex::build(&expanded.gates, expanded.num_qubits); + + // Use noise map (with batched S-type) when stochastic noise is present. + // For coherent-only (idle_rz), the bitmap-enhanced linear scan is faster. + let has_stochastic = p1 > 0.0 || p2 > 0.0 || p_meas > 0.0 || p_prep > 0.0; + + let noise_map = if has_stochastic { + Some(pecos_eeg::heisenberg::build_noise_map( + &expanded.gates, + &noise, + &gate_index.expansion_gates, + )) + } else { + None + }; + + // Parallelize across detectors — each walk is independent. + // Uses sparse traversal (heap + gate index) for O(active_gates) instead of O(all_gates). + use rayon::prelude::*; + let results: Vec<(usize, f64)> = detectors + .par_iter() + .map(|det| { + let p = pecos_eeg::heisenberg::heisenberg_sparse( + &expanded.gates, + &det.stabilizer, + &noise, + &stab, + prune, + &gate_index, + noise_map.as_deref(), + ); + (det.id, p) + }) + .collect(); + + Ok(results) +} + +/// Compute exact pairwise detection rates via backward Heisenberg walk. +/// +/// For each pair of detectors (i, j), computes P(Di AND Dj both fire) +/// using the identity: +/// P(Di=1, Dj=1) = (P(Di) + P(Dj) - P_walk(Si*Sj)) / 2 +/// where P_walk(Si*Sj) is a Heisenberg walk with the product stabilizer. +/// +/// Returns a list of ((det_i, det_j), joint_probability) tuples. +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0, prune=1e-12))] +pub fn exact_pairwise_rates( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + prune: f64, +) -> PyResult> { + let noise = pecos_eeg::noise::UniformNoise { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(tick_circuit)?; + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let (detectors, _observables) = extract_detectors_expanded(tick_circuit, &expanded)?; + + let init_gates: Vec = (0..expanded.num_original_qubits) + .map(|q| pecos_eeg::expand::make_gate(pecos_core::gate_type::GateType::PZ, &[q])) + .collect(); + let stab = + pecos_eeg::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); + + let gate_index = pecos_eeg::expand::GateIndex::build(&expanded.gates, expanded.num_qubits); + let has_stochastic = p1 > 0.0 || p2 > 0.0 || p_meas > 0.0 || p_prep > 0.0; + let noise_map = if has_stochastic { + Some(pecos_eeg::heisenberg::build_noise_map( + &expanded.gates, + &noise, + &gate_index.expansion_gates, + )) + } else { + None + }; + + let walk = |stab_bm: &Bm| -> f64 { + pecos_eeg::heisenberg::heisenberg_sparse( + &expanded.gates, + stab_bm, + &noise, + &stab, + prune, + &gate_index, + noise_map.as_deref(), + ) + }; + + // Marginals + let marginals: Vec = detectors.iter().map(|d| walk(&d.stabilizer)).collect(); + + // Pairwise: P(Di AND Dj) = (P(Di) + P(Dj) - P_walk(Si*Sj)) / 2 + use rayon::prelude::*; + let pairs: Vec<(usize, usize)> = (0..detectors.len()) + .flat_map(|i| ((i + 1)..detectors.len()).map(move |j| (i, j))) + .collect(); + + let results: Vec<((usize, usize), f64)> = pairs + .par_iter() + .map(|&(i, j)| { + let product = detectors[i].stabilizer.multiply(&detectors[j].stabilizer); + let p_product = walk(&product); + let p_joint = (marginals[i] + marginals[j] - p_product) / 2.0; + ((detectors[i].id, detectors[j].id), p_joint.max(0.0)) + }) + .collect(); + + Ok(results) +} + +/// Build a coherent DEM with exact Heisenberg marginals. +/// +/// Combines backward mechanism extraction (correct structure) with +/// Heisenberg-exact per-detector rates (correct probabilities). +/// Fits mechanism probabilities to match the exact marginals. +/// +/// Returns the DEM as a Stim-format string. +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0, prune=1e-12))] +pub fn coherent_dem_exact( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + prune: f64, +) -> PyResult { + let noise = pecos_eeg::noise::UniformNoise { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(tick_circuit)?; + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let (detectors, observables) = extract_detectors_expanded(tick_circuit, &expanded)?; + let gate_index = pecos_eeg::expand::GateIndex::build(&expanded.gates, expanded.num_qubits); + + // Compute Heisenberg exact marginals + let init_gates: Vec = (0..expanded.num_original_qubits) + .map(|q| pecos_eeg::expand::make_gate(pecos_core::gate_type::GateType::PZ, &[q])) + .collect(); + let stab = + pecos_eeg::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); + let has_stochastic = p1 > 0.0 || p2 > 0.0 || p_meas > 0.0 || p_prep > 0.0; + let noise_map = if has_stochastic { + Some(pecos_eeg::heisenberg::build_noise_map( + &expanded.gates, + &noise, + &gate_index.expansion_gates, + )) + } else { + None + }; + + let walk = |stab_bm: &Bm| -> f64 { + pecos_eeg::heisenberg::heisenberg_sparse( + &expanded.gates, + stab_bm, + &noise, + &stab, + prune, + &gate_index, + noise_map.as_deref(), + ) + }; + + let mut marginals = vec![0.0_f64; detectors.iter().map(|d| d.id + 1).max().unwrap_or(0)]; + for det in &detectors { + let p = walk(&det.stabilizer); + if det.id < marginals.len() { + marginals[det.id] = p; + } + } + + // Compute pairwise rates via product stabilizer walks + let mut pairwise: Vec<((usize, usize), f64)> = Vec::new(); + for i in 0..detectors.len() { + for j in (i + 1)..detectors.len() { + let product = detectors[i].stabilizer.multiply(&detectors[j].stabilizer); + let p_product = walk(&product); + let p_joint = + (marginals[detectors[i].id] + marginals[detectors[j].id] - p_product) / 2.0; + if p_joint > 1e-10 { + pairwise.push(((detectors[i].id, detectors[j].id), p_joint.max(0.0))); + } + } + } + + // Build DEM with exact marginals + pairwise + let entries = pecos_eeg::coherent_dem::build_coherent_dem_exact( + &expanded.gates, + &noise, + &detectors, + &observables, + &gate_index.expansion_gates, + &marginals, + Some(&pairwise), + ); + + Ok(pecos_eeg::dem_mapping::format_dem(&entries)) +} + +/// Build coherent DEM with proper X/Z decomposition for MWPM decoders. +/// +/// Returns (raw_dem, decomposed_dem) where the decomposed version uses +/// Pauli provenance to split hyperedges into X ^ Z components. +/// Probabilities are fitted to Heisenberg-exact marginals via L-BFGS. +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0, prune=1e-12))] +pub fn coherent_dem_decomposed( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + prune: f64, +) -> PyResult<(String, String)> { + let noise = pecos_eeg::noise::UniformNoise { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(tick_circuit)?; + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let (detectors, observables) = extract_detectors_expanded(tick_circuit, &expanded)?; + let gate_index = pecos_eeg::expand::GateIndex::build(&expanded.gates, expanded.num_qubits); + + // Compute Heisenberg-exact marginals for probability fitting + let init_gates: Vec = (0..expanded.num_original_qubits) + .map(|q| pecos_eeg::expand::make_gate(pecos_core::gate_type::GateType::PZ, &[q])) + .collect(); + let stab = + pecos_eeg::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); + let has_stochastic = p1 > 0.0 || p2 > 0.0 || p_meas > 0.0 || p_prep > 0.0; + let noise_map = if has_stochastic { + Some(pecos_eeg::heisenberg::build_noise_map( + &expanded.gates, + &noise, + &gate_index.expansion_gates, + )) + } else { + None + }; + + let walk = |stab_bm: &Bm| -> f64 { + pecos_eeg::heisenberg::heisenberg_sparse( + &expanded.gates, + stab_bm, + &noise, + &stab, + prune, + &gate_index, + noise_map.as_deref(), + ) + }; + + let mut marginals = vec![0.0_f64; detectors.iter().map(|d| d.id + 1).max().unwrap_or(0)]; + for det in &detectors { + let p = walk(&det.stabilizer); + if det.id < marginals.len() { + marginals[det.id] = p; + } + } + + // Pairwise rates for better fitting + let mut pairwise: Vec<((usize, usize), f64)> = Vec::new(); + for i in 0..detectors.len() { + for j in (i + 1)..detectors.len() { + let product = detectors[i].stabilizer.multiply(&detectors[j].stabilizer); + let p_product = walk(&product); + let p_joint = + (marginals[detectors[i].id] + marginals[detectors[j].id] - p_product) / 2.0; + if p_joint > 1e-10 { + pairwise.push(((detectors[i].id, detectors[j].id), p_joint.max(0.0))); + } + } + } + + // Build decomposable entries with exact-fitted probabilities + let entries = pecos_eeg::coherent_dem::build_coherent_dem_exact_decomposable( + &expanded.gates, + &noise, + &detectors, + &observables, + &gate_index.expansion_gates, + &marginals, + Some(&pairwise), + ); + + let raw = pecos_eeg::dem_mapping::format_dem( + &entries + .iter() + .map(|e| pecos_eeg::dem_mapping::DemEntry { + event: e.event.clone(), + probability: e.probability, + }) + .collect::>(), + ); + let decomposed = pecos_eeg::dem_mapping::format_dem_decomposed(&entries); + + Ok((raw, decomposed)) +} + +/// Compute exact k-body detector correlation table from Heisenberg walks. +/// +/// Returns exact joint detection probabilities for all detector subsets +/// up to `max_order`. No DEM approximation — captures all coherent +/// interference. Useful for decoders that can consume raw correlation data. +/// +/// Returns a list of (detector_indices, probability) pairs. +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0, max_order=2, prune=1e-12))] +pub fn exact_correlation_table( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + max_order: usize, + prune: f64, +) -> PyResult, f64)>> { + let noise = pecos_eeg::noise::UniformNoise { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(tick_circuit)?; + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let (detectors, _observables) = extract_detectors_expanded(tick_circuit, &expanded)?; + + let init_gates: Vec = (0..expanded.num_original_qubits) + .map(|q| pecos_eeg::expand::make_gate(pecos_core::gate_type::GateType::PZ, &[q])) + .collect(); + let stab = + pecos_eeg::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); + + let table = pecos_eeg::correlation_table::compute_correlation_table( + &expanded.gates, + &noise, + &detectors, + &_observables, + &stab, + expanded.num_qubits, + max_order, + prune, + ); + + // String labels: "D0", "D1", "L0" — consistent with Stim DEM format. + let mut result: Vec<(Vec, f64)> = table + .rates + .into_iter() + .map(|(k, v)| (k.into_iter().map(|d| format!("D{d}")).collect(), v)) + .collect(); + + // Observable correlations with string labels + for ((det_ids, obs_id), prob) in table.observable_rates { + let mut labels: Vec = det_ids.into_iter().map(|d| format!("D{d}")).collect(); + labels.push(format!("L{obs_id}")); + result.push((labels, prob)); + } + + Ok(result) +} + +/// Build a graphlike DEM from exact Heisenberg correlation tables. +/// +/// Bypasses the DEM independent error model entirely. Edge weights come +/// directly from exact pairwise correlations (including all coherent +/// interference effects). For MWPM decoders. +/// +/// Returns a DEM string suitable for pymatching/fusion_blossom. +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0, max_order=2, prune=1e-12))] +pub fn correlation_matching_dem( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + max_order: usize, + prune: f64, +) -> PyResult { + let noise = pecos_eeg::noise::UniformNoise { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(tick_circuit)?; + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let (detectors, observables) = extract_detectors_expanded(tick_circuit, &expanded)?; + + let init_gates: Vec = (0..expanded.num_original_qubits) + .map(|q| pecos_eeg::expand::make_gate(pecos_core::gate_type::GateType::PZ, &[q])) + .collect(); + let stab = + pecos_eeg::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); + + let table = pecos_eeg::correlation_table::compute_correlation_table( + &expanded.gates, + &noise, + &detectors, + &observables, + &stab, + expanded.num_qubits, + max_order, + prune, + ); + + Ok(table.to_matching_dem()) +} + +/// Compress mid-round noise to round boundaries (optional optimization). +/// +/// Propagates gate noise forward to round boundaries, accumulating +/// faults with the same effective Pauli label. Measurement and prep +/// noise kept at original positions. Returns compression statistics. +/// +/// For stochastic Pauli noise: exact. For coherent: within-round exact. +/// +/// Returns (original_count, compressed_count, boundary_noise_labels). +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0))] +pub fn compress_noise( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, +) -> PyResult<(usize, usize)> { + let noise = pecos_eeg::noise::UniformNoise { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(tick_circuit)?; + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let gate_index = pecos_eeg::expand::GateIndex::build(&expanded.gates, expanded.num_qubits); + + let result = pecos_eeg::noise_compression::compress_noise_to_boundaries( + &expanded.gates, + &noise, + &gate_index.expansion_gates, + ); + + Ok((result.original_count, result.compressed_count)) +} + +/// Complete noise characterization: correlations + mechanisms + DEM. +/// +/// Returns a JSON string containing: +/// - Exact k-body detector correlations (from Heisenberg walks) +/// - Detector-observable cross-correlations +/// - Mechanism catalog with fitted probabilities +/// - DEM string for standard decoders +/// +/// This is the unified output that captures everything a decoder needs. +#[pyfunction] +#[pyo3(signature = (tick_circuit, idle_rz=0.0, p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0, max_order=2, prune=1e-12, compress=false))] +pub fn noise_characterization( + tick_circuit: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + max_order: usize, + prune: f64, + compress: bool, +) -> PyResult<(String, String, String)> { + let base_noise = pecos_eeg::noise::UniformNoise { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(tick_circuit)?; + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let (detectors, observables) = extract_detectors_expanded(tick_circuit, &expanded)?; + + let init_gates: Vec = (0..expanded.num_original_qubits) + .map(|q| pecos_eeg::expand::make_gate(pecos_core::gate_type::GateType::PZ, &[q])) + .collect(); + let stab = + pecos_eeg::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); + + // For compressed mode: use original noise for Heisenberg targets (exact), + // compressed noise for mechanism structure (fast). + let structure_noise: Option> = if compress { + let gate_index = pecos_eeg::expand::GateIndex::build(&expanded.gates, expanded.num_qubits); + let compressed = pecos_eeg::noise_compression::compress_noise_to_boundaries( + &expanded.gates, + &base_noise, + &gate_index.expansion_gates, + ); + Some(Box::new( + pecos_eeg::noise_compression::CompressedNoiseSpec::from_compressed(&compressed), + )) + } else { + None + }; + + let det_meas_ids = extract_meas_id_defs(tick_circuit, "detectors")?; + let obs_meas_ids = extract_meas_id_defs(tick_circuit, "observables")?; + + let nc = pecos_eeg::noise_characterization::NoiseCharacterization::build( + &expanded.gates, + &base_noise, + structure_noise.as_deref(), + &detectors, + &observables, + &stab, + expanded.num_qubits, + max_order, + prune, + &det_meas_ids, + &obs_meas_ids, + ); + + Ok(( + nc.to_json(), + nc.to_dem_string(), + nc.to_dem_string_decomposed(), + )) +} + +/// Build a coherent DEM via backward mechanism extraction. +/// +// -- Internal -- + +fn parse_h_formula(s: &str) -> PyResult { + match s { + "taylor" => Ok(pecos_eeg::dem_mapping::HFormula::Taylor), + "sin_squared" => Ok(pecos_eeg::dem_mapping::HFormula::SinSquared), + "exact_commuting" => Ok(pecos_eeg::dem_mapping::HFormula::ExactCommuting), + "exact_subset" => Ok(pecos_eeg::dem_mapping::HFormula::ExactSubset), + _ => Err(pyo3::exceptions::PyValueError::new_err(format!( + "Unknown h_formula '{s}'. Use 'taylor', 'sin_squared', 'exact_commuting', or 'exact_subset'." + ))), + } +} + +fn run_eeg( + py_tc: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + h_formula: &str, + bch_order: u32, +) -> PyResult> { + let noise = NoiseModel { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(py_tc)?; + + // Step 1: Expand circuit (defer measurements) + let expanded = pecos_eeg::expand::expand_circuit(&gates); + + // Step 2: Propagate through expanded circuit + let result = pecos_eeg::circuit::analyze_expanded(&expanded.gates, &noise); + + // Step 3: Build detectors using expanded circuit mapping + let (detectors, observables) = extract_detectors_expanded(py_tc, &expanded)?; + + // Step 4: Compute stabilizer group from EXPANDED circuit (pre-readout). + // Use expanded frame directly — no lossy original-frame mapping. + // Strip trailing deferred MZ(aux) from the expanded circuit. + let expanded_pre_readout = exclude_final_mz(&expanded.gates); + let stab_group = pecos_eeg::stabilizer::StabilizerGroup::from_circuit( + &expanded_pre_readout, + expanded.num_qubits, + ); + + // Step 5: Build DEM (stabilizer check in expanded frame) + let config = pecos_eeg::dem_mapping::EegConfig { + h_formula: parse_h_formula(h_formula)?, + bch_order: if bch_order >= 2 { + pecos_eeg::dem_mapping::BchOrder::Second + } else { + pecos_eeg::dem_mapping::BchOrder::First + }, + }; + Ok(pecos_eeg::dem_mapping::build_dem_configured( + &result.generators, + &detectors, + &observables, + Some(&stab_group), + &config, + )) +} + +fn run_eeg_decomposable( + py_tc: &Bound<'_, PyAny>, + idle_rz: f64, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + h_formula: &str, + bch_order: u32, +) -> PyResult<( + Vec, + Vec, +)> { + let noise = NoiseModel { + idle_rz, + p1, + p2, + p_meas, + p_prep, + }; + let gates = extract_gates(py_tc)?; + let expanded = pecos_eeg::expand::expand_circuit(&gates); + let result = pecos_eeg::circuit::analyze_expanded(&expanded.gates, &noise); + let (detectors, observables) = extract_detectors_expanded(py_tc, &expanded)?; + let expanded_pre_readout = exclude_final_mz(&expanded.gates); + let stab_group = pecos_eeg::stabilizer::StabilizerGroup::from_circuit( + &expanded_pre_readout, + expanded.num_qubits, + ); + let config = pecos_eeg::dem_mapping::EegConfig { + h_formula: parse_h_formula(h_formula)?, + bch_order: if bch_order >= 2 { + pecos_eeg::dem_mapping::BchOrder::Second + } else { + pecos_eeg::dem_mapping::BchOrder::First + }, + }; + let raw = pecos_eeg::dem_mapping::build_dem_configured( + &result.generators, + &detectors, + &observables, + Some(&stab_group), + &config, + ); + let decomposable = pecos_eeg::dem_mapping::build_dem_decomposable( + &result.generators, + &detectors, + &observables, + Some(&stab_group), + &config, + ); + Ok((raw, decomposable)) +} + +/// Strip all trailing MZ from expanded circuit (deferred measurements). +fn exclude_final_mz(gates: &[Gate]) -> Vec { + let last_non_mz = gates + .iter() + .rposition(|g| g.gate_type != pecos_core::gate_type::GateType::MZ); + match last_non_mz { + Some(idx) => gates[..=idx].to_vec(), + None => Vec::new(), + } +} + +fn extract_gates(py_tc: &Bound<'_, PyAny>) -> PyResult> { + let num_ticks: usize = py_tc.call_method0("num_ticks")?.extract()?; + let mut gates = Vec::new(); + + for tick_idx in 0..num_ticks { + let py_tick = py_tc.call_method1("get_tick", (tick_idx,))?; + let py_gates = py_tick.call_method0("gates")?; + let gate_list: Vec> = py_gates.extract()?; + + // Collect all gates in this tick first, then emit them. + // This preserves the simultaneity of gates within a tick: + // all Clifford gates in the tick execute "at once", and noise + // is injected after the entire tick (not between gates). + let mut tick_gates = Vec::new(); + + for gate in &gate_list { + let name: String = gate.getattr("gate_type")?.getattr("name")?.extract()?; + let qubits: Vec = gate.getattr("qubits")?.extract()?; + + match name.as_str() { + "CX" | "CY" | "CZ" | "SWAP" | "SZZ" | "SZZdg" | "SXX" | "SXXdg" | "SYY" + | "SYYdg" => { + // Split multi-pair 2q gates into individual pairs + let gt = match name.as_str() { + "CX" => pecos_core::gate_type::GateType::CX, + "CY" => pecos_core::gate_type::GateType::CY, + "CZ" => pecos_core::gate_type::GateType::CZ, + "SWAP" => pecos_core::gate_type::GateType::SWAP, + "SZZ" => pecos_core::gate_type::GateType::SZZ, + "SZZdg" => pecos_core::gate_type::GateType::SZZdg, + "SXX" => pecos_core::gate_type::GateType::SXX, + "SXXdg" => pecos_core::gate_type::GateType::SXXdg, + "SYY" => pecos_core::gate_type::GateType::SYY, + _ => pecos_core::gate_type::GateType::SYYdg, + }; + for pair in qubits.chunks(2) { + if pair.len() == 2 { + tick_gates.push(Gate { + gate_type: gt, + qubits: GateQubits::from_iter(pair.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: GateMeasIds::new(), + }); + } + } + } + // Single-qubit gates: split multi-qubit into individual per-qubit gates + "H" | "X" | "Y" | "Z" | "SZ" | "SZdg" | "SX" | "SXdg" | "SY" | "SYdg" | "F" + | "Fdg" => { + let gt = match name.as_str() { + "H" => pecos_core::gate_type::GateType::H, + "X" => pecos_core::gate_type::GateType::X, + "Y" => pecos_core::gate_type::GateType::Y, + "Z" => pecos_core::gate_type::GateType::Z, + "SZ" => pecos_core::gate_type::GateType::SZ, + "SZdg" => pecos_core::gate_type::GateType::SZdg, + "SX" => pecos_core::gate_type::GateType::SX, + "SXdg" => pecos_core::gate_type::GateType::SXdg, + "SY" => pecos_core::gate_type::GateType::SY, + "F" => pecos_core::gate_type::GateType::F, + "Fdg" => pecos_core::gate_type::GateType::Fdg, + _ => pecos_core::gate_type::GateType::SYdg, + }; + for &q in &qubits { + tick_gates.push(Gate { + gate_type: gt, + qubits: GateQubits::from_iter(std::iter::once(QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: GateMeasIds::new(), + }); + } + } + // PZ/QAlloc: split multi-qubit into per-qubit + "QAlloc" | "PZ" => { + for &q in &qubits { + tick_gates.push(Gate { + gate_type: pecos_core::gate_type::GateType::PZ, + qubits: GateQubits::from_iter(std::iter::once(QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: GateMeasIds::new(), + }); + } + } + // MZ: keep multi-qubit (expansion handles per-qubit) + _ => { + let gt = match name.as_str() { + "MZ" | "MeasureFree" => pecos_core::gate_type::GateType::MZ, + "RZ" => pecos_core::gate_type::GateType::RZ, + "Idle" | "I" => pecos_core::gate_type::GateType::Idle, + other => { + return Err(pyo3::exceptions::PyValueError::new_err(format!( + "EEG extract_gates: unsupported gate type {other:?}" + ))); + } + }; + let mut g = Gate { + gate_type: gt, + qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: GateMeasIds::new(), + }; + if gt == pecos_core::gate_type::GateType::RZ { + if let Ok(angles) = gate.getattr("angles")?.extract::>() { + if let Some(&a) = angles.first() { + g.angles.push(Angle64::from_radians(a)); + } + } + } + tick_gates.push(g); + } + } + } + + // Emit all gates from this tick. Gates within a tick are simultaneous, + // so noise injected after the last gate correctly sees all tick gates + // as already applied. + gates.extend(tick_gates); + } + + Ok(gates) +} + +fn extract_detectors_expanded( + py_tc: &Bound<'_, PyAny>, + expanded: &pecos_eeg::expand::ExpandedCircuit, +) -> PyResult<(Vec, Vec)> { + // In the expanded circuit, each measurement record k maps to a + // Z-measurement on auxiliary qubit expanded.measurement_qubit[k]. + // + // A detector defined by records {r1, r2, ...} has stabilizer + // Z_{aux_r1} * Z_{aux_r2} * ... in the expanded circuit. + let num_meas = expanded.measurement_qubit.len(); + + let mut detectors = Vec::new(); + let mut observables = Vec::new(); + + // Parse detector JSON from metadata + if let Ok(det_json_str) = py_tc.call_method1("get_meta", ("detectors",)) { + if let Ok(det_json) = det_json_str.extract::() { + if let Ok(det_list) = serde_json_parse_detectors(&det_json) { + for (id, records) in det_list { + let mut bm = Bm::default(); + for &rec in &records { + let abs_idx = if rec < 0 { num_meas as i32 + rec } else { rec }; + if abs_idx >= 0 && (abs_idx as usize) < num_meas { + // Map to AUXILIARY qubit in expanded circuit + let aux_qubit = expanded.measurement_qubit[abs_idx as usize]; + bm.z_bits.xor_bit(aux_qubit); + } + } + detectors.push(Detector { id, stabilizer: bm }); + } + } + } + } + + // Parse observable JSON from metadata + if let Ok(obs_json_str) = py_tc.call_method1("get_meta", ("observables",)) { + if let Ok(obs_json) = obs_json_str.extract::() { + if let Ok(obs_list) = serde_json_parseobservables(&obs_json) { + for (id, records) in obs_list { + let mut bm = Bm::default(); + for &rec in &records { + let abs_idx = if rec < 0 { num_meas as i32 + rec } else { rec }; + if abs_idx >= 0 && (abs_idx as usize) < num_meas { + let aux_qubit = expanded.measurement_qubit[abs_idx as usize]; + bm.z_bits.xor_bit(aux_qubit); + } + } + observables.push(Observable { id, pauli: bm }); + } + } + } + } + + Ok((detectors, observables)) +} + +/// Minimal JSON parser for detector definitions (avoids serde dependency). +/// Parses [{"id": N, "records": [R1, R2, ...], ...}, ...] +fn serde_json_parse_detectors(json: &str) -> Result)>, String> { + // Simple approach: find "id" and "records" fields via string scanning + let mut result = Vec::new(); + let mut pos = 0; + while let Some(start) = json[pos..].find("{") { + let start = pos + start; + let end = json[start..] + .find("}") + .map(|e| start + e + 1) + .ok_or_else(|| "Unmatched brace".to_string())?; + let entry = &json[start..end]; + + let id = extract_json_int(entry, "\"id\"").unwrap_or(result.len() as i64) as usize; + let records = extract_json_int_array(entry, "\"records\"").unwrap_or_default(); + + result.push((id, records)); + pos = end; + } + Ok(result) +} + +fn serde_json_parseobservables(json: &str) -> Result)>, String> { + serde_json_parse_detectors(json) // Same format +} + +/// Extract MeasId definitions from circuit metadata JSON. +fn extract_meas_id_defs( + py_tc: &Bound<'_, pyo3::PyAny>, + key: &str, // "detectors" or "observables" +) -> PyResult, Vec)>> { + let mut result = Vec::new(); + if let Ok(json_str) = py_tc.call_method1("get_meta", (key,)) { + if let Ok(s) = json_str.extract::() { + // Parse JSON: each item has id, meas_ids (optional), records + let items = parse_json_items(&s); + for (idx, (records, meas_ids)) in items.iter().enumerate() { + result.push((idx, meas_ids.clone(), records.clone())); + } + } + } + Ok(result) +} + +/// Parse JSON array items, extracting records and meas_ids fields. +fn parse_json_items(json: &str) -> Vec<(Vec, Vec)> { + let mut result = Vec::new(); + // Split by "records" occurrences + let trimmed = json.trim(); + if !trimmed.starts_with('[') { + return result; + } + + // Simple state machine: find each {...} block and extract fields + let mut depth = 0; + let mut block_start = None; + for (i, ch) in trimmed.char_indices() { + match ch { + '{' => { + if depth == 1 { + block_start = Some(i); + } + depth += 1; + } + '}' => { + depth -= 1; + if depth == 1 { + if let Some(start) = block_start { + let block = &trimmed[start..=i]; + let records = extract_json_int_array(block, "records").unwrap_or_default(); + let meas_ids = extract_json_int_array(block, "meas_ids") + .map(|v| v.into_iter().map(|x| x as usize).collect()) + .unwrap_or_default(); + result.push((records, meas_ids)); + } + } + } + '[' if depth == 0 => { + depth = 1; + } + ']' if depth == 1 => { + break; + } + _ => {} + } + } + result +} + +fn extract_json_int(s: &str, key: &str) -> Option { + let key_pos = s.find(key)?; + let after_key = &s[key_pos + key.len()..]; + let colon = after_key.find(':')?; + let value_str = after_key[colon + 1..].trim(); + // Read digits (possibly with minus) + let end = value_str + .find(|c: char| !c.is_ascii_digit() && c != '-') + .unwrap_or(value_str.len()); + value_str[..end].trim().parse().ok() +} + +fn extract_json_int_array(s: &str, key: &str) -> Option> { + let key_pos = s.find(key)?; + let after_key = &s[key_pos + key.len()..]; + let bracket_start = after_key.find('[')?; + let bracket_end = after_key[bracket_start..].find(']')? + bracket_start; + let array_str = &after_key[bracket_start + 1..bracket_end]; + let values: Vec = array_str + .split(',') + .filter_map(|v| v.trim().parse().ok()) + .collect(); + Some(values) +} diff --git a/python/pecos-rslib-exp/src/lib.rs b/python/pecos-rslib-exp/src/lib.rs new file mode 100644 index 000000000..da803d18b --- /dev/null +++ b/python/pecos-rslib-exp/src/lib.rs @@ -0,0 +1,91 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Python bindings for experimental PECOS simulators. +//! +//! Exposes `StabMps` (stabilizer + MPS hybrid) and `Mast` (magic state +//! injection) from `pecos-stab-tn` via `PyO3`. + +mod coherent_idle_channel; +mod eeg_bindings; +mod mast_bindings; +mod sim_neo_bindings; +mod stab_mps_bindings; +pub mod stabmps_builder; + +use pecos_core::Angle64; +use pyo3::prelude::*; +use pyo3::types::PyDict; + +pub(crate) fn extract_angle( + params: Option<&Bound<'_, PyDict>>, + gate_name: &str, +) -> PyResult { + let params = params.ok_or_else(|| { + PyErr::new::(format!( + "{gate_name} requires params with 'angle'" + )) + })?; + let py_any = params.get_item("angle")?.ok_or_else(|| { + PyErr::new::(format!( + "{gate_name} requires an 'angle' parameter" + )) + })?; + let radians: f64 = py_any.extract().map_err(|_| { + PyErr::new::(format!( + "Expected a float 'angle' parameter for {gate_name}" + )) + })?; + Ok(Angle64::from_radians(radians)) +} + +#[pymodule] +fn pecos_rslib_exp(m: &Bound<'_, PyModule>) -> PyResult<()> { + m.add_class::()?; + m.add_class::()?; + m.add_class::()?; + m.add_class::()?; + m.add_class::()?; + m.add_function(wrap_pyfunction!(sim_neo_bindings::py_sim_neo, m)?)?; + m.add_function(wrap_pyfunction!(sim_neo_bindings::stab_mps, m)?)?; + m.add_function(wrap_pyfunction!(sim_neo_bindings::depolarizing, m)?)?; + m.add_class::()?; + m.add_class::()?; + m.add_function(wrap_pyfunction!(sim_neo_bindings::statevec, m)?)?; + m.add_function(wrap_pyfunction!(sim_neo_bindings::stabilizer, m)?)?; + m.add_class::()?; + m.add_class::()?; + m.add_class::()?; + m.add_function(wrap_pyfunction!(sim_neo_bindings::meas_sampling, m)?)?; + m.add_function(wrap_pyfunction!(sim_neo_bindings::dem_sampling, m)?)?; + m.add_class::()?; + m.add_class::()?; + m.add_class::()?; + m.add_class::()?; + m.add_class::()?; + m.add_function(wrap_pyfunction!(sim_neo_bindings::fault_catalog, m)?)?; + // DEM generation functions + m.add_function(wrap_pyfunction!(eeg_bindings::exact_detection_rates, m)?)?; + m.add_function(wrap_pyfunction!(eeg_bindings::exact_pairwise_rates, m)?)?; + m.add_function(wrap_pyfunction!(eeg_bindings::coherent_dem_exact, m)?)?; + m.add_function(wrap_pyfunction!(eeg_bindings::coherent_dem_decomposed, m)?)?; + m.add_function(wrap_pyfunction!(eeg_bindings::exact_correlation_table, m)?)?; + m.add_function(wrap_pyfunction!(eeg_bindings::correlation_matching_dem, m)?)?; + m.add_function(wrap_pyfunction!(eeg_bindings::noise_characterization, m)?)?; + m.add_function(wrap_pyfunction!(eeg_bindings::compress_noise, m)?)?; + m.add_function(wrap_pyfunction!(eeg_bindings::perturbative_dem, m)?)?; + m.add_function(wrap_pyfunction!(eeg_bindings::perturbative_dem_events, m)?)?; + m.add_function(wrap_pyfunction!(eeg_bindings::eeg_summary, m)?)?; + m.add_function(wrap_pyfunction!(eeg_bindings::eeg_event_diagnostics, m)?)?; + m.add_function(wrap_pyfunction!(eeg_bindings::eeg_per_detector, m)?)?; + Ok(()) +} diff --git a/python/pecos-rslib-exp/src/mast_bindings.rs b/python/pecos-rslib-exp/src/mast_bindings.rs new file mode 100644 index 000000000..6f8c32e54 --- /dev/null +++ b/python/pecos-rslib-exp/src/mast_bindings.rs @@ -0,0 +1,311 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +use pecos_core::{Angle64, QubitId}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, QuantumSimulator}; +use pecos_stab_tn::stab_mps::mast::Mast; +use pyo3::prelude::*; +use pyo3::types::{PyDict, PySet, PyTuple}; + +#[pyclass(name = "Mast", module = "pecos_rslib_exp")] +pub struct PyMast { + inner: Mast, +} + +impl PyMast { + fn check_qubit(&self, q: usize, method: &str) -> PyResult<()> { + if q >= self.inner.num_qubits() { + return Err(PyErr::new::(format!( + "{method}: qubit {q} out of bounds (num_qubits={})", + self.inner.num_qubits() + ))); + } + Ok(()) + } +} + +#[pymethods] +impl PyMast { + #[new] + #[pyo3(signature = (num_qubits, max_non_clifford, seed=None, lazy_measure=false, merge_rz=false))] + fn new( + num_qubits: usize, + max_non_clifford: usize, + seed: Option, + lazy_measure: bool, + merge_rz: bool, + ) -> Self { + let mut mast = if let Some(s) = seed { + Mast::with_seed(num_qubits, max_non_clifford, s) + } else { + Mast::new(num_qubits, max_non_clifford) + }; + if lazy_measure { + mast = mast.with_lazy_measure(true); + } + if merge_rz { + mast = mast.with_merge_rz(true); + } + PyMast { inner: mast } + } + + fn reset(mut slf: PyRefMut<'_, Self>) -> PyRefMut<'_, Self> { + slf.inner.reset(); + slf + } + + #[getter] + fn num_qubits(&self) -> usize { + self.inner.num_qubits() + } + + #[getter] + fn num_data_qubits(&self) -> usize { + self.inner.num_data_qubits() + } + + #[getter] + fn num_ancillas_used(&self) -> usize { + self.inner.num_ancillas_used() + } + + #[getter] + fn max_bond_dim(&self) -> usize { + self.inner.max_bond_dim() + } + + fn flush(&mut self) { + self.inner.flush(); + } + + fn project_all(&mut self) { + self.inner.project_all(); + } + + // ---- Gate dispatch ---- + + #[pyo3(signature = (symbol, location, params=None))] + fn run_1q_gate( + &mut self, + symbol: &str, + location: usize, + params: Option<&Bound<'_, PyDict>>, + ) -> PyResult> { + self.check_qubit(location, symbol)?; + let q = &[QubitId(location)]; + match symbol { + "I" => Ok(None), + "X" => { + self.inner.x(q); + Ok(None) + } + "Y" => { + self.inner.y(q); + Ok(None) + } + "Z" => { + self.inner.z(q); + Ok(None) + } + "H" | "H1" | "H+z+x" => { + self.inner.h(q); + Ok(None) + } + "F" | "F1" => { + self.inner.f(q); + Ok(None) + } + "Fdg" | "F1d" | "F1dg" => { + self.inner.fdg(q); + Ok(None) + } + "SX" | "SqrtX" | "Q" => { + self.inner.sx(q); + Ok(None) + } + "SXdg" | "SqrtXdg" | "SqrtXd" | "Qd" => { + self.inner.sxdg(q); + Ok(None) + } + "SY" | "SqrtY" | "R" => { + self.inner.sy(q); + Ok(None) + } + "SYdg" | "SqrtYdg" | "SqrtYd" | "Rd" => { + self.inner.sydg(q); + Ok(None) + } + "S" | "SZ" | "SqrtZ" => { + self.inner.sz(q); + Ok(None) + } + "Sd" | "SZdg" | "SqrtZdg" | "SqrtZd" => { + self.inner.szdg(q); + Ok(None) + } + "RX" => { + let angle = crate::extract_angle(params, "RX")?; + self.inner.rx(angle, q); + Ok(None) + } + "RY" => { + let angle = crate::extract_angle(params, "RY")?; + self.inner.ry(angle, q); + Ok(None) + } + "RZ" => { + let angle = crate::extract_angle(params, "RZ")?; + self.inner.rz(angle, q); + Ok(None) + } + "T" => { + self.inner.rz(Angle64::QUARTER_TURN / 2u64, q); + Ok(None) + } + "Tdg" => { + self.inner.rz(-(Angle64::QUARTER_TURN / 2u64), q); + Ok(None) + } + "PZ" | "Init" | "init |0>" => { + let results = self.inner.mz(q); + if results[0].outcome { + self.inner.x(q); + } + Ok(None) + } + "PX" | "Init +X" | "init |+>" => { + let results = self.inner.mz(q); + if results[0].outcome { + self.inner.x(q); + } + self.inner.h(q); + Ok(None) + } + "MZ" | "Measure" | "measure Z" => { + let result = self + .inner + .mz(q) + .into_iter() + .next() + .expect("measurement returned no results"); + Ok(Some(u8::from(result.outcome))) + } + _ => Err(PyErr::new::(format!( + "Unsupported single-qubit gate: {symbol}" + ))), + } + } + + #[pyo3(signature = (symbol, location, params=None))] + fn run_2q_gate( + &mut self, + symbol: &str, + location: &Bound<'_, PyTuple>, + params: Option<&Bound<'_, PyDict>>, + ) -> PyResult> { + if location.len() != 2 { + return Err(PyErr::new::( + "Two-qubit gate requires exactly 2 qubit locations", + )); + } + let q1: usize = location.get_item(0)?.extract()?; + let q2: usize = location.get_item(1)?.extract()?; + self.check_qubit(q1, symbol)?; + self.check_qubit(q2, symbol)?; + let pair = &[(QubitId(q1), QubitId(q2))]; + match symbol { + "CX" | "CNOT" => { + self.inner.cx(pair); + Ok(None) + } + "CY" => { + self.inner.cy(pair); + Ok(None) + } + "CZ" => { + self.inner.cz(pair); + Ok(None) + } + "SXX" => { + self.inner.sxx(pair); + Ok(None) + } + "SXXdg" => { + self.inner.sxxdg(pair); + Ok(None) + } + "SYY" => { + self.inner.syy(pair); + Ok(None) + } + "SYYdg" => { + self.inner.syydg(pair); + Ok(None) + } + "SZZ" => { + self.inner.szz(pair); + Ok(None) + } + "SZZdg" => { + self.inner.szzdg(pair); + Ok(None) + } + "SWAP" => { + self.inner.swap(pair); + Ok(None) + } + "RZZ" => { + let angle = crate::extract_angle(params, "RZZ")?; + self.inner.rzz(angle, pair); + Ok(None) + } + _ => Err(PyErr::new::(format!( + "Unsupported two-qubit gate: {symbol}" + ))), + } + } + + #[pyo3(signature = (symbol, locations, **params))] + fn run_gate( + &mut self, + symbol: &str, + locations: &Bound<'_, PyAny>, + params: Option<&Bound<'_, PyDict>>, + py: Python<'_>, + ) -> PyResult> { + let output = PyDict::new(py); + let locations_set: Bound = locations.clone().cast_into()?; + for location in locations_set.iter() { + let loc_tuple: Bound<'_, PyTuple> = if location.is_instance_of::() { + location.clone().cast_into()? + } else { + PyTuple::new(py, std::slice::from_ref(&location))? + }; + let result = match loc_tuple.len() { + 1 => { + let qubit: usize = loc_tuple.get_item(0)?.extract()?; + self.run_1q_gate(symbol, qubit, params)? + } + 2 => self.run_2q_gate(symbol, &loc_tuple, params)?, + _ => { + return Err(PyErr::new::( + "Gate location must be 1 or 2 qubits", + )); + } + }; + if let Some(value) = result { + output.set_item(location, value)?; + } + } + Ok(output.into()) + } +} diff --git a/python/pecos-rslib-exp/src/sim_neo_bindings.rs b/python/pecos-rslib-exp/src/sim_neo_bindings.rs new file mode 100644 index 000000000..cb1ee8752 --- /dev/null +++ b/python/pecos-rslib-exp/src/sim_neo_bindings.rs @@ -0,0 +1,1652 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! Python bindings for `sim_neo` with builder pattern. +//! +//! Mirrors the Rust-side API: +//! ```python +//! results = (sim_neo(tc) +//! .quantum(stab_mps().lazy_measure().max_bond_dim(128)) +//! .noise(depolarizing().p1(0.003).p2(0.003).p_meas(0.003).p_prep(0.003).idle_rz(0.05)) +//! .shots(5000) +//! .seed(42) +//! .run()) +//! ``` + +use pecos_core::{Angle64, PauliString}; +use pecos_neo::command::CommandBuilder; +use pecos_neo::noise::{ + ComposableNoiseModel, MeasurementChannel, PreparationChannel, SingleQubitChannel, + TwoQubitChannel, +}; +use pecos_neo::tool::sim_neo; +use pecos_simulators::measurement_sampler::SampleResult; +use pyo3::prelude::*; + +// ============================================================================ +// Columnar raw measurement result (stays in Rust memory) +// ============================================================================ + +/// Raw measurement batch — common result type for all sim_neo backends. +/// +/// Stores either columnar bit-packed data (meas_sampling) or row-major +/// data (stabilizer/statevec). The Python API is identical regardless of +/// storage: `result[shot]`, `result.get(shot, meas)`, iteration, `len()`. +#[pyclass(name = "RawMeasurementResult", module = "pecos_rslib_exp")] +pub struct PyRawMeasurementResult { + storage: RawMeasurementStorage, +} + +enum RawMeasurementStorage { + /// Columnar bit-packed (from meas_sampling geometric sampler). + Columnar(SampleResult), + /// Row-major (from gate-by-gate stabilizer/statevec simulation). + RowMajor { + rows: Vec>, + num_measurements: usize, + }, +} + +impl RawMeasurementStorage { + fn num_shots(&self) -> usize { + match self { + Self::Columnar(s) => s.shots(), + Self::RowMajor { rows, .. } => rows.len(), + } + } + + fn num_measurements(&self) -> usize { + match self { + Self::Columnar(s) => s.num_measurements(), + Self::RowMajor { + num_measurements, .. + } => *num_measurements, + } + } + + fn get(&self, shot: usize, measurement: usize) -> u8 { + match self { + Self::Columnar(s) => u8::from(s.get(shot, measurement).0), + Self::RowMajor { rows, .. } => rows[shot][measurement], + } + } + + fn get_shot(&self, shot: usize) -> Vec { + match self { + Self::Columnar(s) => { + let n = s.num_measurements(); + let mut row = Vec::with_capacity(n); + for meas in 0..n { + row.push(u8::from(s.get(shot, meas).0)); + } + row + } + Self::RowMajor { rows, .. } => rows[shot].clone(), + } + } +} + +impl PyRawMeasurementResult { + /// Convert a signed Python index to a checked usize. + /// Negative indices raise IndexError (no Python-list-style wrapping). + fn check_index(idx: isize, len: usize, name: &str) -> PyResult { + if idx < 0 { + return Err(pyo3::exceptions::PyIndexError::new_err(format!( + "negative {name} index {idx}" + ))); + } + let u = idx as usize; + if u >= len { + return Err(pyo3::exceptions::PyIndexError::new_err(format!( + "{name} {u} out of range ({len})" + ))); + } + Ok(u) + } + + /// Construct from columnar SampleResult (meas_sampling path). + pub fn from_columnar(result: SampleResult) -> Self { + Self { + storage: RawMeasurementStorage::Columnar(result), + } + } + + /// Construct from row-major data (stabilizer/statevec path). + pub fn from_rows(rows: Vec>) -> Self { + let num_measurements = rows.first().map_or(0, |r| r.len()); + Self { + storage: RawMeasurementStorage::RowMajor { + rows, + num_measurements, + }, + } + } +} + +#[pymethods] +impl PyRawMeasurementResult { + /// Number of shots. + #[getter] + fn num_shots(&self) -> usize { + self.storage.num_shots() + } + + /// Number of measurements per shot. + #[getter] + fn num_measurements(&self) -> usize { + self.storage.num_measurements() + } + + /// Get a single measurement bit (0 or 1). + fn get(&self, shot: isize, measurement: isize) -> PyResult { + let s = Self::check_index(shot, self.storage.num_shots(), "shot")?; + let m = Self::check_index(measurement, self.storage.num_measurements(), "measurement")?; + Ok(self.storage.get(s, m)) + } + + /// Get one full shot as a list of u8. + fn get_shot(&self, shot: isize) -> PyResult> { + let s = Self::check_index(shot, self.storage.num_shots(), "shot")?; + Ok(self.storage.get_shot(s)) + } + + /// Materialize all shots as list[list[int]]. + fn to_list(&self) -> Vec> { + let n = self.storage.num_shots(); + (0..n).map(|i| self.storage.get_shot(i)).collect() + } + + fn __len__(&self) -> usize { + self.storage.num_shots() + } + + fn __getitem__(&self, shot: isize) -> PyResult> { + let s = Self::check_index(shot, self.storage.num_shots(), "index")?; + Ok(self.storage.get_shot(s)) + } +} + +// ============================================================================ +// Noise model builder +// ============================================================================ + +/// Builder for composable noise models. +/// +/// Example: +/// depolarizing().p1(0.003).p2(0.003).p_meas(0.003).p_prep(0.003).idle_rz(0.05) +#[pyclass( + name = "NoiseModelBuilder", + skip_from_py_object, + module = "pecos_rslib_exp" +)] +#[derive(Clone, Default)] +pub struct PyNoiseModelBuilder { + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + idle_rz_angle: f64, +} + +#[pymethods] +impl PyNoiseModelBuilder { + #[new] + fn new() -> Self { + Self::default() + } + + /// Single-qubit depolarizing rate (X/Y/Z each with p/3 after unitary 1q gates). + fn p1(&self, p: f64) -> Self { + Self { + p1: p, + ..self.clone() + } + } + + /// Two-qubit depolarizing rate (15 Paulis each with p/15 after unitary 2q gates). + fn p2(&self, p: f64) -> Self { + Self { + p2: p, + ..self.clone() + } + } + + /// Measurement bit-flip rate (symmetric, after MZ). + fn p_meas(&self, p: f64) -> Self { + Self { + p_meas: p, + ..self.clone() + } + } + + /// Preparation error rate (X flip after PZ/QAlloc). + fn p_prep(&self, p: f64) -> Self { + Self { + p_prep: p, + ..self.clone() + } + } + + /// Coherent idle RZ angle (radians) applied to both qubits after each CX. + fn idle_rz(&self, angle: f64) -> Self { + Self { + idle_rz_angle: angle, + ..self.clone() + } + } +} + +impl PyNoiseModelBuilder { + fn build_noise(&self) -> Option { + let has_noise = self.p1 > 0.0 + || self.p2 > 0.0 + || self.p_meas > 0.0 + || self.p_prep > 0.0 + || self.idle_rz_angle > 0.0; + + if !has_noise { + return None; + } + + let mut noise = ComposableNoiseModel::new(); + if self.p1 > 0.0 { + noise = noise.add_channel(SingleQubitChannel::depolarizing(self.p1)); + } + if self.p2 > 0.0 { + noise = noise.add_channel(TwoQubitChannel::depolarizing(self.p2)); + } + if self.p_meas > 0.0 { + noise = noise.add_channel(MeasurementChannel::symmetric(self.p_meas)); + } + if self.p_prep > 0.0 { + noise = noise.add_channel(PreparationChannel::new(self.p_prep)); + } + if self.idle_rz_angle > 0.0 { + noise = noise.add_channel(crate::coherent_idle_channel::CoherentIdleChannel::new( + self.idle_rz_angle, + )); + } + Some(noise) + } +} + +/// Create a noise model builder. +#[pyfunction] +pub fn depolarizing() -> PyNoiseModelBuilder { + PyNoiseModelBuilder::new() +} + +/// Marker type for the stabilizer (SparseStab) backend. +/// +/// Pass to `.quantum()` to select the stabilizer simulator. +/// +/// Example: +/// sim_neo(tc).quantum(stabilizer()).noise(depolarizing().p2(0.01)).shots(10000).run() +#[pyclass( + name = "StabilizerBuilder", + skip_from_py_object, + module = "pecos_rslib_exp" +)] +#[derive(Clone)] +pub struct PyStabilizerBuilder; + +#[pymethods] +impl PyStabilizerBuilder { + #[new] + fn new() -> Self { + Self + } +} + +/// Marker type for the state vector backend. +/// +/// Pass to `.quantum()` to select the state vector simulator. +/// Supports arbitrary gates including non-Clifford (T, RZ, etc.). +/// +/// Example: +/// sim_neo(tc).quantum(statevec()).noise(depolarizing().idle_rz(0.05)).shots(10000).run() +#[pyclass( + name = "StateVecBuilder", + skip_from_py_object, + module = "pecos_rslib_exp" +)] +#[derive(Clone)] +pub struct PyStateVecBuilder; + +#[pymethods] +impl PyStateVecBuilder { + #[new] + fn new() -> Self { + Self + } +} + +/// Create a state vector backend builder. +/// +/// Example: +/// sim_neo(tc).quantum(statevec()).noise(...).shots(10000).run() +#[pyfunction] +pub fn statevec() -> PyStateVecBuilder { + PyStateVecBuilder +} + +/// Create a stabilizer (SparseStab) backend builder. +/// +/// Example: +/// sim_neo(tc).quantum(stabilizer()).noise(...).shots(10000).run() +#[pyfunction] +pub fn stabilizer() -> PyStabilizerBuilder { + PyStabilizerBuilder +} + +// ============================================================================ +// StabMps backend builder +// ============================================================================ + +/// Builder for StabMps backend configuration. +/// +/// Example: +/// stab_mps().lazy_measure().max_bond_dim(128) +#[pyclass( + name = "StabMpsBuilder", + skip_from_py_object, + module = "pecos_rslib_exp" +)] +#[derive(Clone)] +pub struct PyStabMpsBuilder { + pub(crate) inner: crate::stabmps_builder::StabMpsBuilder, +} + +#[pymethods] +impl PyStabMpsBuilder { + #[new] + fn new() -> Self { + Self { + inner: crate::stabmps_builder::StabMpsBuilder::new(), + } + } + + fn lazy_measure(mut slf: PyRefMut<'_, Self>) -> PyRefMut<'_, Self> { + slf.inner.lazy_measure = true; + slf + } + + fn max_bond_dim(mut slf: PyRefMut<'_, Self>, bd: usize) -> PyRefMut<'_, Self> { + slf.inner.max_bond_dim = bd; + slf + } + + fn max_truncation_error(mut slf: PyRefMut<'_, Self>, err: f64) -> PyRefMut<'_, Self> { + slf.inner.max_truncation_error = Some(err); + slf + } + + fn merge_rz(mut slf: PyRefMut<'_, Self>) -> PyRefMut<'_, Self> { + slf.inner.merge_rz = true; + slf + } +} + +/// Create a StabMps backend builder. +#[pyfunction] +pub fn stab_mps() -> PyStabMpsBuilder { + PyStabMpsBuilder::new() +} + +// ============================================================================ +// sim_neo builder +// ============================================================================ + +/// Measurement sampling backend builder. +#[pyclass( + name = "MeasSamplingBuilder", + skip_from_py_object, + module = "pecos_rslib_exp" +)] +#[derive(Clone)] +pub struct PyMeasSamplingBuilder { + method: String, +} + +#[pymethods] +impl PyMeasSamplingBuilder { + #[new] + #[pyo3(signature = (method="auto"))] + fn new(method: &str) -> Self { + Self { + method: method.to_string(), + } + } +} + +/// Create a measurement sampling backend builder. +/// +/// Samples raw measurement rows from a whole-circuit measurement model. Fast, handles coherent noise at any distance. +/// +/// Methods: +/// - "auto": uses coherent_dem if idle_rz > 0, else stochastic (default) +/// - "stochastic": DEM from backward Pauli propagation +/// - "coherent": DEM from EEG backward Heisenberg walk +#[pyfunction] +#[pyo3(signature = (method="auto"))] +pub fn meas_sampling(method: &str) -> PyMeasSamplingBuilder { + PyMeasSamplingBuilder::new(method) +} + +/// DEM sampling backend builder. +#[pyclass( + name = "DemSamplingBuilder", + skip_from_py_object, + module = "pecos_rslib_exp" +)] +#[derive(Clone)] +pub struct PyDemSamplingBuilder { + method: String, +} + +#[pymethods] +impl PyDemSamplingBuilder { + #[new] + #[pyo3(signature = (method="auto"))] + fn new(method: &str) -> Self { + Self { + method: method.to_string(), + } + } +} + +/// Create a DEM sampling backend builder. +/// +/// Samples raw measurement rows from a detector-error-model measurement +/// model. This is the canonical name for the DEM-backed measurement sampler; +/// `meas_sampling()` remains available as a compatibility alias. +/// +/// Methods: +/// - "auto": uses coherent_dem if idle_rz > 0, else stochastic (default) +/// - "stochastic": DEM from backward Pauli propagation +/// - "coherent": DEM from EEG backward Heisenberg walk +#[pyfunction] +#[pyo3(signature = (method="auto"))] +pub fn dem_sampling(method: &str) -> PyDemSamplingBuilder { + PyDemSamplingBuilder::new(method) +} + +/// Builder for sim_neo simulations. Mirrors the Rust-side `SimNeoBuilder`. +#[pyclass( + name = "SimNeoBuilder", + skip_from_py_object, + module = "pecos_rslib_exp" +)] +#[derive(Clone)] +pub struct PySimNeoBuilder { + commands: pecos_neo::command::CommandQueue, + /// Original Rust TickCircuit for meas_sampling (avoids reconstruction). + /// Wrapped in Arc for Clone compatibility with pyo3. + tick_circuit: std::sync::Arc, + shots: usize, + seed: u64, + noise_config: Option, + backend: String, + stabmps_config: Option, + dem_sampling_method: Option, +} + +#[pymethods] +impl PySimNeoBuilder { + /// Set the quantum backend. + /// + /// Accepts: + /// - `state_vec()` — state vector (exact, supports non-Clifford gates) + /// - `stabilizer()` — SparseStab (fast Clifford-only) + /// - `stab_mps()` — hybrid stabilizer-MPS (Clifford + T gates) + /// + /// Example: + /// sim_neo(tc).quantum(state_vec()).noise(...).run() + /// sim_neo(tc).quantum(stabilizer()).noise(...).run() + /// sim_neo(tc).quantum(stab_mps().lazy_measure()).noise(...).run() + fn quantum(&self, builder: &Bound<'_, PyAny>) -> PyResult { + let mut c = self.clone(); + if builder.is_instance_of::() { + let b: PyRef<'_, PyDemSamplingBuilder> = builder.extract()?; + c.backend = "dem_sampling".to_string(); + c.dem_sampling_method = Some(b.method.clone()); + c.stabmps_config = None; + } else if builder.is_instance_of::() { + let b: PyRef<'_, PyMeasSamplingBuilder> = builder.extract()?; + c.backend = "meas_sampling".to_string(); + c.dem_sampling_method = Some(b.method.clone()); + c.stabmps_config = None; + } else if builder.is_instance_of::() { + let b: PyRef<'_, PyStabMpsBuilder> = builder.extract()?; + c.backend = "stabmps".to_string(); + c.stabmps_config = Some(b.inner.clone()); + c.dem_sampling_method = None; + } else if builder.is_instance_of::() { + c.backend = "stabilizer".to_string(); + c.stabmps_config = None; + c.dem_sampling_method = None; + } else if builder.is_instance_of::() { + c.backend = "statevec".to_string(); + c.stabmps_config = None; + c.dem_sampling_method = None; + } else { + return Err(pyo3::exceptions::PyTypeError::new_err( + "quantum() expects statevec(), stabilizer(), stab_mps(), dem_sampling(), or meas_sampling()", + )); + } + Ok(c) + } + + /// Set the noise model. + fn noise(&self, noise_builder: &PyNoiseModelBuilder) -> Self { + let mut c = self.clone(); + c.noise_config = Some(noise_builder.clone()); + c + } + + /// Set number of shots. + fn shots(&self, n: usize) -> Self { + let mut c = self.clone(); + c.shots = n; + c + } + + /// Set random seed. + fn seed(&self, s: u64) -> Self { + let mut c = self.clone(); + c.seed = s; + c + } + + /// Run the simulation and return per-shot measurement outcomes. + /// + /// All backends return `RawMeasurementResult` which supports: + /// `result[shot]`, `result.get(shot, meas)`, `len(result)`, iteration. + fn run(&self) -> PyResult { + if self.backend == "dem_sampling" || self.backend == "meas_sampling" { + return self.run_dem_sampling(); + } + + let noise = self + .noise_config + .as_ref() + .and_then(PyNoiseModelBuilder::build_noise); + + let mut builder = sim_neo(self.commands.clone()) + .shots(self.shots) + .seed(self.seed); + + if let Some(n) = noise { + builder = builder.noise(n); + } + + match self.backend.as_str() { + "stabmps" => { + let config = self.stabmps_config.clone().unwrap_or_default(); + builder = builder.quantum(pecos_neo::tool::custom_backend_from_factory(config)); + } + "statevec" => { + builder = builder.quantum(pecos_neo::tool::state_vector()); + } + "stabilizer" => { + builder = builder.quantum(pecos_neo::tool::sparse_stab()); + } + _ => { + return Err(PyErr::new::(format!( + "Unknown backend: {}", + self.backend + ))); + } + } + + let mut sim = builder.build(); + let results = sim.run(); + + let mut all_shots = Vec::with_capacity(self.shots); + for shot_outcomes in &results.outcomes { + let meas: Vec = shot_outcomes.iter().map(|o| u8::from(o.outcome)).collect(); + all_shots.push(meas); + } + + Ok(PyRawMeasurementResult::from_rows(all_shots)) + } +} + +impl PySimNeoBuilder { + /// DEM sampling backend: dispatches to stochastic or coherent path based on method. + fn run_dem_sampling(&self) -> PyResult { + let noise_config = self.noise_config.as_ref().ok_or_else(|| { + pyo3::exceptions::PyValueError::new_err("DEM sampling requires .noise() to be set") + })?; + + let method = self.dem_sampling_method.as_deref().unwrap_or("auto"); + + let has_coherent = noise_config.idle_rz_angle.abs() > 1e-15; + + match method { + "stochastic" => { + if has_coherent { + return Err(pyo3::exceptions::PyValueError::new_err( + "DEM sampling method='stochastic' cannot handle idle_rz noise. \ + Use method='coherent' or method='auto'.", + )); + } + self.run_stochastic_meas_columnar() + } + "coherent" | "coherent_approx" | "coherent_exact" => { + let rows = self.run_coherent_meas_sampling(noise_config, method)?; + Ok(PyRawMeasurementResult::from_rows(rows)) + } + "auto" => { + if has_coherent { + let rows = self.run_coherent_meas_sampling(noise_config, "coherent_approx")?; + Ok(PyRawMeasurementResult::from_rows(rows)) + } else { + self.run_stochastic_meas_columnar() + } + } + other => Err(pyo3::exceptions::PyValueError::new_err(format!( + "Unknown DEM sampling method: {other:?}. \ + Use 'auto', 'stochastic', 'coherent', 'coherent_approx', or 'coherent_exact'." + ))), + } + } + + /// Stochastic path: columnar raw-measurement sampling. + fn run_stochastic_meas_columnar(&self) -> PyResult { + use pecos_qec::fault_tolerance::fault_sampler::{ + self, RawMeasurementPlan, StochasticNoiseParams, + }; + + let noise_config = self.noise_config.as_ref().ok_or_else(|| { + pyo3::exceptions::PyRuntimeError::new_err("DEM sampling requires .noise() to be set") + })?; + + let history = run_symbolic_sim_with_pz(&self.tick_circuit)?; + + let noise = StochasticNoiseParams { + p1: noise_config.p1, + p2: noise_config.p2, + p_meas: noise_config.p_meas, + p_prep: noise_config.p_prep, + }; + let mechanisms = fault_sampler::build_fault_table(&self.tick_circuit, &noise) + .map_err(|e| pyo3::exceptions::PyRuntimeError::new_err(e.to_string()))?; + + let plan = RawMeasurementPlan::new(&history, mechanisms); + let result = plan.sample(self.shots, self.seed); + + Ok(PyRawMeasurementResult::from_columnar(result)) + } + + /// Coherent path: EEG DemGenerator with measurement synthesis. + fn run_coherent_meas_sampling( + &self, + noise_config: &PyNoiseModelBuilder, + method: &str, + ) -> PyResult>> { + use pecos_eeg::dem_generator::select_generator; + use pecos_eeg::dem_simulator::{CircuitMeasurementMeta, run_dem_simulation}; + + // Extract metadata from stored TickCircuit + let num_meas_attr = self + .tick_circuit + .get_meta("num_measurements") + .and_then(|a| { + if let pecos_quantum::Attribute::String(s) = a { + s.parse::().ok() + } else { + None + } + }) + .ok_or_else(|| { + pyo3::exceptions::PyValueError::new_err( + "TickCircuit missing num_measurements metadata", + ) + })?; + let det_json = self + .tick_circuit + .get_meta("detectors") + .and_then(|a| { + if let pecos_quantum::Attribute::String(s) = a { + Some(s.clone()) + } else { + None + } + }) + .unwrap_or_else(|| "[]".to_string()); + let obs_json = self + .tick_circuit + .get_meta("observables") + .and_then(|a| { + if let pecos_quantum::Attribute::String(s) = a { + Some(s.clone()) + } else { + None + } + }) + .unwrap_or_else(|| "[]".to_string()); + + #[derive(serde::Deserialize)] + struct RecDef { + records: Vec, + } + + let det_records: Vec> = serde_json::from_str::>(&det_json) + .map(|defs| defs.iter().map(|d| d.records.clone()).collect()) + .unwrap_or_default(); + let obs_records: Vec> = serde_json::from_str::>(&obs_json) + .map(|defs| defs.iter().map(|d| d.records.clone()).collect()) + .unwrap_or_default(); + + let meta = CircuitMeasurementMeta { + num_measurements: num_meas_attr, + detector_records: det_records, + observable_records: obs_records, + }; + + let noise = pecos_eeg::noise::UniformNoise { + idle_rz: noise_config.idle_rz_angle, + p1: noise_config.p1, + p2: noise_config.p2, + p_meas: noise_config.p_meas, + p_prep: noise_config.p_prep, + }; + + let gates = commands_to_gates(&self.commands); + let generator = select_generator(method, noise_config.idle_rz_angle); + + let result = run_dem_simulation( + &gates, + &noise, + &meta, + generator.as_ref(), + self.shots, + self.seed, + ); + Ok(result.measurements) + } +} + +/// Convert CommandQueue to Vec for EEG analysis. +fn commands_to_gates(commands: &pecos_neo::command::CommandQueue) -> Vec { + use pecos_core::{Gate, GateAngles, GateMeasIds, GateParams, GateQubits}; + + commands + .iter() + .map(|cmd| { + let qubits = GateQubits::from_iter(cmd.qubits.iter().copied()); + let mut angles = GateAngles::new(); + for &a in &cmd.angles { + angles.push(a); + } + // Convert pecos_neo::GateType to pecos_core::GateType + let gate_type: pecos_core::gate_type::GateType = cmd.gate_type.into(); + Gate { + gate_type, + qubits, + angles, + params: GateParams::new(), + meas_ids: GateMeasIds::new(), + } + }) + .collect() +} + +// ============================================================================ +// Entry point +// ============================================================================ + +/// Create a sim_neo simulation builder from a TickCircuit. +/// +/// Example: +/// results = (sim_neo(tc) +/// .quantum(stab_mps().lazy_measure().max_bond_dim(128)) +/// .noise(depolarizing().p1(0.003).p2(0.003).p_meas(0.003).idle_rz(0.05)) +/// .shots(5000) +/// .seed(42) +/// .run()) +#[pyfunction] +#[pyo3(name = "sim_neo")] +pub fn py_sim_neo(tick_circuit: &Bound<'_, PyAny>) -> PyResult { + let commands = extract_commands(tick_circuit)?; + + // Build a Rust TickCircuit from the Python object. + // This is the canonical circuit representation used by DemSampler. + let tc = build_rust_tick_circuit(tick_circuit)?; + + Ok(PySimNeoBuilder { + commands, + tick_circuit: std::sync::Arc::new(tc), + shots: 1, + seed: 42, + noise_config: None, + backend: "statevec".to_string(), + stabmps_config: None, + dem_sampling_method: None, + }) +} + +/// Build a proper Rust TickCircuit from a Python TickCircuit object. +/// +/// First tries to extract the inner Rust TickCircuit directly (fast path). +/// Falls back to rebuilding from Python gate iteration (slow path). +fn build_rust_tick_circuit(py_tc: &Bound<'_, PyAny>) -> PyResult { + // Fast path: try to access the inner TickCircuit directly. + // The Python TickCircuit wraps `pub inner: TickCircuit` — access via + // the `_inner_tick_circuit()` method if available, or via serialization. + if let Ok(tc_bytes) = py_tc.call_method0("_serialize_inner") { + if let Ok(bytes) = tc_bytes.extract::>() { + // Deserialize — but TickCircuit doesn't impl serde. Skip. + let _ = bytes; + } + } + + // The only reliable fast path: call `to_dag_circuit()` on the Python TC, + // then use DemSampler::from_circuit on that DagCircuit. But we can't get + // the DagCircuit across crate boundaries easily. + // + // For now: reconstruct via gate iteration (matches original structure if + // we respect tick boundaries from the Python object). + build_rust_tick_circuit_from_gates(py_tc) +} + +/// Reconstruct TickCircuit from Python gate iteration, preserving tick structure. +/// +/// Respects the original tick boundaries: all gates from the same Python tick +/// go into the same Rust tick. Uses typed .mz() for measurements and .pz() for +/// prep within each tick (these consume the TickHandle, so we process them after +/// other gates in the tick). +fn build_rust_tick_circuit_from_gates( + py_tc: &Bound<'_, PyAny>, +) -> PyResult { + use pecos_quantum::{Attribute, TickMeasRef}; + + let num_ticks: usize = py_tc.call_method0("num_ticks")?.extract()?; + let mut tc = pecos_quantum::TickCircuit::default(); + let mut all_meas_refs: Vec = Vec::new(); + + for tick_idx in 0..num_ticks { + let py_tick = py_tc.call_method1("get_tick", (tick_idx,))?; + let py_gates = py_tick.call_method0("gates")?; + let gates: Vec> = py_gates.extract()?; + + // Separate gates by type: MZ, PZ, and other + let mut mz_qubits: Vec = Vec::new(); + let mut pz_qubits: Vec = Vec::new(); + let mut other_gates: Vec = Vec::new(); + + for gate in &gates { + let gate_type_obj = gate.getattr("gate_type")?; + let gate_name: String = format!("{:?}", gate_type_obj); + let gate_name = gate_name + .split('.') + .last() + .unwrap_or(&gate_name) + .to_string(); + let py_qubits = gate.getattr("qubits")?; + let qubits: Vec = py_qubits.extract()?; + let qubit_ids: Vec = + qubits.iter().map(|&q| pecos_core::QubitId(q)).collect(); + + match gate_name.as_str() { + "MZ" | "Measure" | "MeasureFree" => { + mz_qubits.extend(qubit_ids); + } + "QAlloc" | "PZ" | "Prep" => { + pz_qubits.extend(qubit_ids); + } + _ => { + let core_gate = build_gate_from_python(gate, &gate_name, &qubit_ids)?; + other_gates.push(core_gate); + } + } + } + + // Add PZ first (prep before other gates) + if !pz_qubits.is_empty() { + tc.tick().pz(&pz_qubits); + } + + // Add other gates in one tick (error on qubit conflicts) + if !other_gates.is_empty() { + let mut tick_handle = tc.tick(); + for g in &other_gates { + if let Err(e) = tick_handle.try_add_gate(g.clone()) { + return Err(pyo3::exceptions::PyRuntimeError::new_err(format!( + "Gate conflict in tick {tick_idx}: {e}" + ))); + } + } + } + + // Add MZ last (measure after other gates) + if !mz_qubits.is_empty() { + let refs = tc.tick().mz(&mz_qubits); + all_meas_refs.extend(refs); + } + } + + // Copy metadata from Python TickCircuit + if let Ok(num_meas) = py_tc.call_method1("get_meta", ("num_measurements",)) { + if let Ok(s) = num_meas.extract::() { + tc.set_meta("num_measurements", Attribute::String(s)); + } + } + if let Ok(det_json) = py_tc.call_method1("get_meta", ("detectors",)) { + if let Ok(s) = det_json.extract::() { + // Create structured annotations from JSON + create_annotations_from_json(&mut tc, &s, &all_meas_refs, true); + tc.set_meta("detectors", Attribute::String(s)); + } + } + if let Ok(obs_json) = py_tc.call_method1("get_meta", ("observables",)) { + if let Ok(s) = obs_json.extract::() { + create_annotations_from_json(&mut tc, &s, &all_meas_refs, false); + tc.set_meta("observables", Attribute::String(s)); + } + } + copy_operator_annotations_from_python(py_tc, &mut tc)?; + + // Compact for performance + tc.compact_ticks(); + + Ok(tc) +} + +fn copy_operator_annotations_from_python( + py_tc: &pyo3::Bound<'_, pyo3::PyAny>, + tc: &mut pecos_quantum::TickCircuit, +) -> PyResult<()> { + let Ok(annotations) = py_tc.call_method0("annotations") else { + return Ok(()); + }; + + for ann in annotations.try_iter()? { + let ann = ann?; + let kind: String = ann.get_item("kind")?.extract()?; + if kind != "operator" { + continue; + } + let pauli_obj = ann.get_item("pauli")?; + let pauli_text = pauli_obj.str()?.to_string(); + let pauli = parse_python_pauli_string(&pauli_text).ok_or_else(|| { + pyo3::exceptions::PyValueError::new_err(format!( + "Could not parse Pauli operator annotation: {pauli_text}" + )) + })?; + let label: Option = ann.get_item("label")?.extract()?; + if let Some(label) = label { + tc.pauli_operator_labeled(&label, pauli); + } else { + tc.pauli_operator(pauli); + } + } + + Ok(()) +} + +fn parse_python_pauli_string(text: &str) -> Option { + let text = text.trim(); + let text = text + .strip_prefix("+i*") + .or_else(|| text.strip_prefix("-i*")) + .or_else(|| text.strip_prefix('-')) + .unwrap_or(text) + .trim(); + if text.is_empty() || text == "I" { + return Some(PauliString::new()); + } + + let mut paulis = Vec::new(); + for token in text.split_whitespace() { + let mut chars = token.chars(); + let p = match chars.next()? { + 'X' | 'x' => pecos_core::Pauli::X, + 'Y' | 'y' => pecos_core::Pauli::Y, + 'Z' | 'z' => pecos_core::Pauli::Z, + 'I' | 'i' => continue, + _ => return None, + }; + let rest = chars.as_str().strip_prefix('_').unwrap_or(chars.as_str()); + let qubit = rest.parse::().ok()?; + paulis.push((p, pecos_core::QubitId(qubit))); + } + + Some(PauliString::with_phase_and_paulis( + pecos_core::QuarterPhase::PlusOne, + paulis, + )) +} + +/// Create detector or observable annotations from JSON metadata. +fn create_annotations_from_json( + tc: &mut pecos_quantum::TickCircuit, + json_str: &str, + all_meas_refs: &[pecos_quantum::TickMeasRef], + is_detector: bool, +) { + #[derive(serde::Deserialize)] + struct RecDef { + records: Vec, + } + + let num_meas = all_meas_refs.len(); + if let Ok(defs) = serde_json::from_str::>(json_str) { + for def in &defs { + let refs: Vec = def + .records + .iter() + .filter_map(|&rec| { + let abs_idx = (num_meas as i32 + rec) as usize; + all_meas_refs.get(abs_idx).copied() + }) + .collect(); + if !refs.is_empty() { + if is_detector { + tc.detector(&refs); + } else { + tc.observable(&refs); + } + } + } + } +} + +/// Build a pecos_core::Gate from a Python gate object. +fn build_gate_from_python( + gate: &Bound<'_, PyAny>, + gate_name: &str, + qubit_ids: &[pecos_core::QubitId], +) -> PyResult { + use pecos_core::gate_type::GateType; + use pecos_core::{Gate, GateAngles, GateMeasIds, GateParams, GateQubits}; + + let gate_type = match gate_name { + "H" => GateType::H, + "X" => GateType::X, + "Y" => GateType::Y, + "Z" => GateType::Z, + "F" => GateType::F, + "Fdg" => GateType::Fdg, + "CX" | "CNOT" => GateType::CX, + "CY" => GateType::CY, + "CZ" => GateType::CZ, + "SZ" | "S" => GateType::SZ, + "SZdg" | "Sdg" => GateType::SZdg, + "SX" => GateType::SX, + "SXdg" => GateType::SXdg, + "SY" => GateType::SY, + "SYdg" => GateType::SYdg, + "T" => GateType::T, + "Tdg" => GateType::Tdg, + "SWAP" => GateType::SWAP, + "RZ" => GateType::RZ, + "RX" => GateType::RX, + "RY" => GateType::RY, + "RZZ" => GateType::RZZ, + "RXX" => GateType::RXX, + "RYY" => GateType::RYY, + "SZZ" => GateType::SZZ, + "SZZdg" => GateType::SZZdg, + "SXX" => GateType::SXX, + "SXXdg" => GateType::SXXdg, + "SYY" => GateType::SYY, + "SYYdg" => GateType::SYYdg, + "R1XY" => GateType::R1XY, + "I" | "Idle" => GateType::I, + other => { + return Err(pyo3::exceptions::PyValueError::new_err(format!( + "Unsupported gate type for meas_sampling simulation: {other}" + ))); + } + }; + + let mut angles = GateAngles::new(); + if let Ok(py_angle) = gate.getattr("angle") { + if let Ok(a) = py_angle.extract::() { + angles.push(pecos_core::Angle64::from_radians(a)); + } + } + if let Ok(py_angles) = gate.getattr("angles") { + if let Ok(a_list) = py_angles.extract::>() { + for a in a_list { + angles.push(pecos_core::Angle64::from_radians(a)); + } + } + } + + Ok(Gate { + gate_type, + qubits: GateQubits::from_iter(qubit_ids.iter().copied()), + angles, + params: GateParams::new(), + meas_ids: GateMeasIds::new(), + }) +} + +// ============================================================================ +// Circuit extraction +// ============================================================================ + +/// Extract a CommandQueue from a Python TickCircuit by iterating its gates. +fn extract_commands(py_tc: &Bound<'_, PyAny>) -> PyResult { + let num_ticks: usize = py_tc.call_method0("num_ticks")?.extract()?; + let mut cb = CommandBuilder::new(); + + for tick_idx in 0..num_ticks { + let py_tick = py_tc.call_method1("get_tick", (tick_idx,))?; + let py_gates = py_tick.call_method0("gates")?; + let gates: Vec> = py_gates.extract()?; + + for gate in &gates { + let gate_type_obj = gate.getattr("gate_type")?; + let name: String = gate_type_obj.getattr("name")?.extract()?; + let qubits: Vec = gate.getattr("qubits")?.extract()?; + + match name.as_str() { + "QAlloc" | "PZ" => { + cb = cb.pz(&qubits); + } + "H" => { + cb = cb.h(&qubits); + } + "F" => { + cb = cb.f(&qubits); + } + "Fdg" => { + cb = cb.fdg(&qubits); + } + "X" => { + cb = cb.x(&qubits); + } + "Y" => { + cb = cb.y(&qubits); + } + "Z" => { + cb = cb.z(&qubits); + } + "SZ" => { + cb = cb.sz(&qubits); + } + "SZdg" => { + cb = cb.szdg(&qubits); + } + "SX" => { + cb = cb.sx(&qubits); + } + "SXdg" => { + cb = cb.sxdg(&qubits); + } + "SY" => { + cb = cb.sy(&qubits); + } + "SYdg" => { + cb = cb.sydg(&qubits); + } + "CX" => { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.cx(&pairs); + } + "CY" => { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.cy(&pairs); + } + "CZ" => { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.cz(&pairs); + } + "SZZ" => { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.szz(&pairs); + } + "SZZdg" => { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.szzdg(&pairs); + } + "SXX" => { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.sxx(&pairs); + } + "SXXdg" => { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.sxxdg(&pairs); + } + "SYY" => { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.syy(&pairs); + } + "SYYdg" => { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.syydg(&pairs); + } + "SWAP" => { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.swap(&pairs); + } + "T" => { + cb = cb.t(&qubits); + } + "Tdg" => { + cb = cb.tdg(&qubits); + } + "MZ" => { + cb = cb.mz(&qubits); + } + "RX" => { + let angles: Vec = gate.getattr("angles")?.extract().unwrap_or_default(); + if let Some(&angle) = angles.first() { + cb = cb.rx(&qubits, Angle64::from_radians(angle)); + } + } + "RY" => { + let angles: Vec = gate.getattr("angles")?.extract().unwrap_or_default(); + if let Some(&angle) = angles.first() { + cb = cb.ry(&qubits, Angle64::from_radians(angle)); + } + } + "RZ" => { + let angles: Vec = gate.getattr("angles")?.extract().unwrap_or_default(); + if let Some(&angle) = angles.first() { + cb = cb.rz(&qubits, Angle64::from_radians(angle)); + } + } + "R1XY" => { + let angles: Vec = gate.getattr("angles")?.extract().unwrap_or_default(); + if angles.len() >= 2 { + cb = cb.r1xy( + &qubits, + Angle64::from_radians(angles[0]), + Angle64::from_radians(angles[1]), + ); + } + } + "RZZ" => { + let angles: Vec = gate.getattr("angles")?.extract().unwrap_or_default(); + if let Some(&angle) = angles.first() { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.rzz(&pairs, Angle64::from_radians(angle)); + } + } + "RXX" => { + let angles: Vec = gate.getattr("angles")?.extract().unwrap_or_default(); + if let Some(&angle) = angles.first() { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.rxx(&pairs, Angle64::from_radians(angle)); + } + } + "RYY" => { + let angles: Vec = gate.getattr("angles")?.extract().unwrap_or_default(); + if let Some(&angle) = angles.first() { + let pairs: Vec<(usize, usize)> = + qubits.chunks(2).map(|c| (c[0], c[1])).collect(); + cb = cb.ryy(&pairs, Angle64::from_radians(angle)); + } + } + "I" | "Idle" => { + // Identity/Idle gates: skip (no-op for simulation) + } + _ => { + return Err(PyErr::new::(format!( + "Unsupported gate type '{}' in extract_commands. \ + Add support in sim_neo_bindings.rs or lower to supported gates \ + with tc.lower_clifford_rotations().", + name + ))); + } + } + } + } + + Ok(cb.build()) +} + +/// Run SymbolicSparseStab through a TickCircuit with proper PZ (reset) semantics. +/// +/// Iterates tick-by-tick to match the TickCircuit's measurement numbering, +/// which is what detector and observable definitions reference. +fn run_symbolic_sim_with_pz( + tc: &pecos_quantum::TickCircuit, +) -> PyResult { + pecos_qec::fault_tolerance::fault_sampler::symbolic_measurement_history(tc) + .map_err(|e| pyo3::exceptions::PyRuntimeError::new_err(e.to_string())) +} + +// ============================================================================ +// Fault Catalog Python API +// ============================================================================ + +/// One fault alternative at a physical location. +#[pyclass(name = "FaultAlternative", module = "pecos_rslib_exp")] +pub struct PyFaultAlternative { + /// "pauli", "measurement_flip", or "prep_flip" + #[pyo3(get)] + kind: String, + /// PauliString object (from pecos.quantum) for Pauli faults, None otherwise + pauli_obj: Py, + /// Measurement indices flipped + #[pyo3(get)] + measurements: Vec, + /// Detector indices flipped + #[pyo3(get)] + detectors: Vec, + /// Observable indices flipped + #[pyo3(get)] + observables: Vec, + /// Tracked-operator indices flipped + #[pyo3(get)] + tracked_ops: Vec, + /// Probability of this alternative given the mechanism fires (1/k) + #[pyo3(get)] + conditional_probability: f64, + /// Marginal per-location alternative probability: p_i / k_i. + /// This is NOT "probability of this fault and no others." Full configuration + /// probabilities require multiplying by no_fault_probability for all other locations. + #[pyo3(get)] + absolute_probability: f64, + /// Total channel probability (same as parent location) + #[pyo3(get)] + channel_probability: f64, +} + +#[pymethods] +impl PyFaultAlternative { + #[getter] + fn pauli(&self, py: Python<'_>) -> Py { + self.pauli_obj.clone_ref(py) + } +} + +/// A physical fault location in the circuit. +#[pyclass(name = "FaultLocation", module = "pecos_rslib_exp")] +pub struct PyFaultLocation { + #[pyo3(get)] + tick: usize, + #[pyo3(get)] + gate_index: usize, + #[pyo3(get)] + gate_type: String, + #[pyo3(get)] + qubits: Vec, + /// "p1", "p2", "p_meas", or "p_prep" + #[pyo3(get)] + channel: String, + #[pyo3(get)] + channel_probability: f64, + /// 1 - channel_probability + #[pyo3(get)] + no_fault_probability: f64, + #[pyo3(get)] + num_alternatives: usize, + #[pyo3(get)] + faults: Vec>, +} + +/// A k-fault configuration yielded by `catalog.fault_configurations(k)`. +#[pyclass(name = "FaultConfiguration", module = "pecos_rslib_exp")] +pub struct PyFaultConfiguration { + #[pyo3(get)] + location_indices: Vec, + #[pyo3(get)] + alternative_indices: Vec, + /// The FaultLocation objects for selected locations. + #[pyo3(get)] + locations: Vec>, + /// The FaultAlternative objects for selected alternatives. + #[pyo3(get)] + faults: Vec>, + #[pyo3(get)] + measurements: Vec, + #[pyo3(get)] + detectors: Vec, + #[pyo3(get)] + observables: Vec, + #[pyo3(get)] + tracked_ops: Vec, + #[pyo3(get)] + selected_probability: f64, + #[pyo3(get)] + configuration_probability: f64, +} + +/// Lazy Python iterator over k-fault configurations. +#[pyclass(name = "FaultConfigurationIter", module = "pecos_rslib_exp")] +pub struct PyFaultConfigurationIter { + /// Owned Rust iterator (self-contained, no borrows). + inner: pecos_qec::fault_tolerance::fault_sampler::OwnedFaultConfigIter, + /// Python-side location objects for building yielded configs. + py_locations: Vec>, +} + +#[pymethods] +impl PyFaultConfigurationIter { + fn __iter__(slf: PyRef<'_, Self>) -> PyRef<'_, Self> { + slf + } + + fn __next__(&mut self, py: Python<'_>) -> Option { + let config = self.inner.next()?; + + // Build .locations and .faults references + let locations: Vec> = config + .location_indices + .iter() + .map(|&i| self.py_locations[i].clone_ref(py)) + .collect(); + let faults: Vec> = config + .location_indices + .iter() + .zip(config.alternative_indices.iter()) + .map(|(&loc_i, &alt_i)| { + let loc = self.py_locations[loc_i].borrow(py); + loc.faults[alt_i].clone_ref(py) + }) + .collect(); + + Some(PyFaultConfiguration { + location_indices: config.location_indices, + alternative_indices: config.alternative_indices, + locations, + faults, + measurements: config.affected_measurements, + detectors: config.affected_detectors, + observables: config.affected_observables, + tracked_ops: config.affected_tracked_ops, + selected_probability: config.selected_probability, + configuration_probability: config.configuration_probability, + }) + } +} + +/// Complete fault catalog for a circuit and noise model. +#[pyclass(name = "FaultCatalog", module = "pecos_rslib_exp")] +pub struct PyFaultCatalog { + /// Physical fault locations with nonzero channel probability. + #[pyo3(get)] + locations: Vec>, + /// Rust-side catalog for iterator support. + rust_catalog: pecos_qec::fault_tolerance::fault_sampler::FaultCatalog, +} + +#[pymethods] +impl PyFaultCatalog { + fn __len__(&self) -> usize { + self.locations.len() + } + + fn __getitem__(&self, py: Python<'_>, index: isize) -> PyResult> { + let len = self.locations.len() as isize; + let index = if index < 0 { len + index } else { index }; + if index < 0 || index >= len { + return Err(pyo3::exceptions::PyIndexError::new_err( + "fault catalog index out of range", + )); + } + Ok(self.locations[index as usize].clone_ref(py)) + } + + fn __iter__(slf: PyRef<'_, Self>, py: Python<'_>) -> PyResult> { + let locations = pyo3::types::PyList::new(py, slf.locations.iter().map(|loc| loc.bind(py)))?; + Ok(locations.call_method0("__iter__")?.unbind()) + } + + /// Lazily iterate all k-fault configurations. + /// + /// Returns an iterator yielding `FaultConfiguration` objects one at a time. + fn fault_configurations( + &self, + py: Python<'_>, + k: usize, + ) -> PyResult> { + use pecos_qec::fault_tolerance::fault_sampler::OwnedFaultConfigIter; + let inner = OwnedFaultConfigIter::new(self.rust_catalog.clone(), k); + let py_locations: Vec> = + self.locations.iter().map(|l| l.clone_ref(py)).collect(); + Py::new( + py, + PyFaultConfigurationIter { + inner, + py_locations, + }, + ) + } +} + +/// Build a fault catalog for a circuit and noise model. +/// +/// Returns a ``FaultCatalog`` object with ``catalog.locations``. The catalog +/// also supports direct iteration, indexing, and ``len(catalog)``. +/// +/// Each location has attribute access: ``loc.tick``, ``loc.gate_type``, +/// ``loc.qubits``, ``loc.faults``. +/// +/// Each ``FaultAlternative`` has: ``fault.kind``, ``fault.pauli`` (a real +/// PECOS ``PauliString`` or ``None``), ``fault.detectors``, ``fault.observables``, +/// ``fault.tracked_ops``, ``fault.measurements``, ``fault.conditional_probability``, +/// ``fault.absolute_probability``, ``fault.channel_probability``. +/// +/// Includes all physical locations with nonzero channel probability, even +/// those with no downstream effect (needed for normalization/accounting). +#[pyfunction] +#[pyo3(signature = (tick_circuit, noise))] +pub fn fault_catalog( + tick_circuit: &Bound<'_, PyAny>, + noise: &PyNoiseModelBuilder, + py: Python<'_>, +) -> PyResult { + use pecos_qec::fault_tolerance::fault_sampler::{ + FaultKind, StochasticNoiseParams, build_fault_catalog, + }; + + let tc = build_rust_tick_circuit(tick_circuit)?; + let noise_params = StochasticNoiseParams { + p1: noise.p1, + p2: noise.p2, + p_meas: noise.p_meas, + p_prep: noise.p_prep, + }; + + let catalog = build_fault_catalog(&tc, &noise_params) + .map_err(|e| pyo3::exceptions::PyRuntimeError::new_err(e.to_string()))?; + + // Import PauliString and Pauli from pecos.quantum + let quantum_mod = py.import("pecos.quantum")?; + let ps_class = quantum_mod.getattr("PauliString")?; + let pauli_enum = quantum_mod.getattr("Pauli")?; + let pauli_x = pauli_enum.getattr("X")?; + let pauli_y = pauli_enum.getattr("Y")?; + let pauli_z = pauli_enum.getattr("Z")?; + + let mut locations = Vec::with_capacity(catalog.locations.len()); + for loc in &catalog.locations { + let mut faults = Vec::with_capacity(loc.faults.len()); + for fault in &loc.faults { + let pauli_obj: Py = if let Some(ps) = &fault.pauli { + let mut pair_list = Vec::new(); + for (p, q) in ps.iter_pairs() { + let py_pauli = match p { + pecos_core::Pauli::X => &pauli_x, + pecos_core::Pauli::Y => &pauli_y, + pecos_core::Pauli::Z => &pauli_z, + pecos_core::Pauli::I => continue, + }; + let pair = pyo3::types::PyTuple::new( + py, + [py_pauli.as_any(), &q.index().into_pyobject(py)?.into_any()], + )?; + pair_list.push(pair.unbind()); + } + let py_list = pyo3::types::PyList::new(py, pair_list.iter().map(|p| p.bind(py)))?; + ps_class.call1((py_list,))?.unbind() + } else { + py.None() + }; + + faults.push(Py::new( + py, + PyFaultAlternative { + kind: match fault.kind { + FaultKind::Pauli => "pauli".to_string(), + FaultKind::MeasurementFlip => "measurement_flip".to_string(), + FaultKind::PrepFlip => "prep_flip".to_string(), + }, + pauli_obj, + measurements: fault.affected_measurements.clone(), + detectors: fault.affected_detectors.clone(), + observables: fault.affected_observables.clone(), + tracked_ops: fault.affected_tracked_ops.clone(), + conditional_probability: fault.conditional_probability, + absolute_probability: fault.absolute_probability, + channel_probability: loc.channel_probability, + }, + )?); + } + + locations.push(Py::new( + py, + PyFaultLocation { + tick: loc.tick, + gate_index: loc.gate_index, + gate_type: format!("{:?}", loc.gate_type), + qubits: loc.qubits.clone(), + channel: match loc.channel { + pecos_qec::fault_tolerance::fault_sampler::FaultChannel::P1 => "p1", + pecos_qec::fault_tolerance::fault_sampler::FaultChannel::P2 => "p2", + pecos_qec::fault_tolerance::fault_sampler::FaultChannel::PMeas => "p_meas", + pecos_qec::fault_tolerance::fault_sampler::FaultChannel::PPrep => "p_prep", + } + .to_string(), + channel_probability: loc.channel_probability, + no_fault_probability: loc.no_fault_probability, + num_alternatives: loc.num_alternatives, + faults, + }, + )?); + } + + Ok(PyFaultCatalog { + locations, + rust_catalog: catalog, + }) +} diff --git a/python/pecos-rslib-exp/src/stab_mps_bindings.rs b/python/pecos-rslib-exp/src/stab_mps_bindings.rs new file mode 100644 index 000000000..cca6efa0e --- /dev/null +++ b/python/pecos-rslib-exp/src/stab_mps_bindings.rs @@ -0,0 +1,508 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +#![allow(clippy::needless_pass_by_value)] // PyO3 requires passing extracted types by value + +use pecos_core::{Angle64, QubitId}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, QuantumSimulator}; +use pecos_stab_tn::stab_mps::{PauliKind, StabMps}; +use pyo3::prelude::*; +use pyo3::types::{PyDict, PyList, PySet, PyTuple}; + +#[pyclass(name = "StabMps", module = "pecos_rslib_exp")] +pub struct PyStabMps { + inner: StabMps, +} + +impl PyStabMps { + fn check_qubit(&self, q: usize, method: &str) -> PyResult<()> { + if q >= self.inner.num_qubits() { + return Err(PyErr::new::(format!( + "{method}: qubit {q} out of bounds (num_qubits={})", + self.inner.num_qubits() + ))); + } + Ok(()) + } +} + +#[pymethods] +impl PyStabMps { + #[new] + #[pyo3(signature = ( + num_qubits, + seed=None, + max_bond_dim=None, + merge_rz=None, + pauli_frame_tracking=None, + lazy_measure=None, + for_sparse_t=None, + auto_grow_bond_dim=None, + auto_grow_max_bond_dim=None, + max_truncation_error=None, + ))] + #[allow(clippy::too_many_arguments)] + fn new( + num_qubits: usize, + seed: Option, + max_bond_dim: Option, + merge_rz: Option, + pauli_frame_tracking: Option, + lazy_measure: Option, + for_sparse_t: Option, + auto_grow_bond_dim: Option, + auto_grow_max_bond_dim: Option, + max_truncation_error: Option, + ) -> Self { + let mut b = StabMps::builder(num_qubits); + if let Some(s) = seed { + b = b.seed(s); + } + if for_sparse_t == Some(true) { + b = b.for_sparse_t(); + } + if let Some(bd) = max_bond_dim { + b = b.max_bond_dim(bd); + } + if merge_rz == Some(true) { + b = b.merge_rz(true); + } + if pauli_frame_tracking == Some(true) { + b = b.pauli_frame_tracking(true); + } + if lazy_measure == Some(true) { + b = b.lazy_measure(true); + } + if let Some(t) = auto_grow_bond_dim { + b = b.auto_grow_bond_dim(t); + } + if let Some(c) = auto_grow_max_bond_dim { + b = b.auto_grow_max_bond_dim(c); + } + if let Some(e) = max_truncation_error { + b = b.max_truncation_error(e); + } + PyStabMps { inner: b.build() } + } + + fn reset(mut slf: PyRefMut<'_, Self>) -> PyRefMut<'_, Self> { + slf.inner.reset(); + slf + } + + #[getter] + fn num_qubits(&self) -> usize { + self.inner.num_qubits() + } + + #[getter] + fn max_bond_dim(&self) -> usize { + self.inner.max_bond_dim() + } + + #[getter] + fn truncation_error(&self) -> f64 { + self.inner.truncation_error() + } + + #[getter] + fn pragmatic_drift_count(&self) -> u64 { + self.inner.pragmatic_drift_count() + } + + fn is_state_exact(&self) -> bool { + self.inner.is_state_exact() + } + + fn flush(&mut self) { + self.inner.flush(); + } + + fn flush_pauli_frame_to_state(&mut self) { + self.inner.flush_pauli_frame_to_state(); + } + + fn state_vector(&self, py: Python<'_>) -> PyResult> { + let sv = self.inner.state_vector(); + let list: Vec<(f64, f64)> = sv.iter().map(|c| (c.re, c.im)).collect(); + Ok(PyList::new(py, &list)?.unbind()) + } + + fn prob_bitstring(&self, bitstring: Vec) -> f64 { + self.inner.prob_bitstring(&bitstring) + } + + // ---- QEC helpers ---- + + fn reset_qubit(&mut self, q: usize) -> PyResult { + self.check_qubit(q, "reset_qubit")?; + Ok(self.inner.reset_qubit(QubitId(q))) + } + + fn pz(&mut self, q: usize) -> PyResult<()> { + self.check_qubit(q, "pz")?; + self.inner.pz(QubitId(q)); + Ok(()) + } + + fn px(&mut self, q: usize) -> PyResult<()> { + self.check_qubit(q, "px")?; + self.inner.px(QubitId(q)); + Ok(()) + } + + fn inject_x_in_frame(&mut self, q: usize) -> PyResult<()> { + self.check_qubit(q, "inject_x_in_frame")?; + self.inner.inject_x_in_frame(QubitId(q)); + Ok(()) + } + + fn inject_y_in_frame(&mut self, q: usize) -> PyResult<()> { + self.check_qubit(q, "inject_y_in_frame")?; + self.inner.inject_y_in_frame(QubitId(q)); + Ok(()) + } + + fn inject_z_in_frame(&mut self, q: usize) -> PyResult<()> { + self.check_qubit(q, "inject_z_in_frame")?; + self.inner.inject_z_in_frame(QubitId(q)); + Ok(()) + } + + fn inject_paulis_in_frame(&mut self, paulis: Vec<(usize, String)>) -> PyResult<()> { + let converted: Vec<(QubitId, PauliKind)> = paulis + .into_iter() + .map(|(q, s)| { + let kind = match s.as_str() { + "X" => PauliKind::X, + "Y" => PauliKind::Y, + "Z" => PauliKind::Z, + _ => { + return Err(PyErr::new::(format!( + "Unknown Pauli kind: {s}. Use 'X', 'Y', or 'Z'." + ))); + } + }; + Ok((QubitId(q), kind)) + }) + .collect::>>()?; + self.inner.inject_paulis_in_frame(&converted); + Ok(()) + } + + fn frame_x_bit(&self, q: usize) -> bool { + self.inner.frame_x_bit(QubitId(q)) + } + + fn frame_z_bit(&self, q: usize) -> bool { + self.inner.frame_z_bit(QubitId(q)) + } + + fn apply_depolarizing(&mut self, q: usize, p: f64) -> Option { + self.inner + .apply_depolarizing(QubitId(q), p) + .map(|k| format!("{k:?}")) + } + + fn apply_depolarizing_all(&mut self, qubits: Vec, p: f64) { + let qs: Vec = qubits.into_iter().map(QubitId).collect(); + self.inner.apply_depolarizing_all(&qs, p); + } + + fn extract_syndromes( + &mut self, + generators: Vec>, + ancilla_qubits: Vec, + ) -> PyResult> { + let gens: Vec> = generators + .into_iter() + .map(|g| { + g.into_iter() + .map(|(q, s)| { + let kind = match s.as_str() { + "X" => PauliKind::X, + "Y" => PauliKind::Y, + "Z" => PauliKind::Z, + _ => { + return Err(PyErr::new::( + format!("Unknown Pauli: {s}"), + )); + } + }; + Ok((q, kind)) + }) + .collect::>>() + }) + .collect::>>()?; + let ancs: Vec = ancilla_qubits.into_iter().map(QubitId).collect(); + Ok(self.inner.extract_syndromes(&gens, &ancs)) + } + + fn pauli_expectation(&self, pauli_string: Vec<(usize, String)>) -> PyResult { + let ps: Vec<(usize, PauliKind)> = pauli_string + .into_iter() + .map(|(q, s)| { + let kind = match s.as_str() { + "X" => PauliKind::X, + "Y" => PauliKind::Y, + "Z" => PauliKind::Z, + _ => { + return Err(PyErr::new::(format!( + "Unknown Pauli: {s}" + ))); + } + }; + Ok((q, kind)) + }) + .collect::>>()?; + Ok(self.inner.pauli_expectation(&ps)) + } + + fn code_state_fidelity(&self, stabilizers: Vec>) -> PyResult { + let stabs: Vec> = stabilizers + .into_iter() + .map(|g| { + g.into_iter() + .map(|(q, s)| { + let kind = match s.as_str() { + "X" => PauliKind::X, + "Y" => PauliKind::Y, + "Z" => PauliKind::Z, + _ => { + return Err(PyErr::new::( + format!("Unknown Pauli: {s}"), + )); + } + }; + Ok((q, kind)) + }) + .collect::>>() + }) + .collect::>>()?; + Ok(self.inner.code_state_fidelity(&stabs)) + } + + fn sample_bitstring(&mut self, num_shots: usize) -> Vec> { + self.inner.sample_bitstring(num_shots) + } + + // ---- Gate dispatch (matches pecos-rslib pattern) ---- + + #[pyo3(signature = (symbol, location, params=None))] + fn run_1q_gate( + &mut self, + symbol: &str, + location: usize, + params: Option<&Bound<'_, PyDict>>, + ) -> PyResult> { + self.check_qubit(location, symbol)?; + let q = &[QubitId(location)]; + match symbol { + "I" => Ok(None), + "X" => { + self.inner.x(q); + Ok(None) + } + "Y" => { + self.inner.y(q); + Ok(None) + } + "Z" => { + self.inner.z(q); + Ok(None) + } + "H" | "H1" | "H+z+x" => { + self.inner.h(q); + Ok(None) + } + "F" | "F1" => { + self.inner.f(q); + Ok(None) + } + "Fdg" | "F1d" | "F1dg" => { + self.inner.fdg(q); + Ok(None) + } + "SX" | "SqrtX" | "Q" => { + self.inner.sx(q); + Ok(None) + } + "SXdg" | "SqrtXdg" | "SqrtXd" | "Qd" => { + self.inner.sxdg(q); + Ok(None) + } + "SY" | "SqrtY" | "R" => { + self.inner.sy(q); + Ok(None) + } + "SYdg" | "SqrtYdg" | "SqrtYd" | "Rd" => { + self.inner.sydg(q); + Ok(None) + } + "S" | "SZ" | "SqrtZ" => { + self.inner.sz(q); + Ok(None) + } + "Sd" | "SZdg" | "SqrtZdg" | "SqrtZd" => { + self.inner.szdg(q); + Ok(None) + } + "RX" => { + let angle = crate::extract_angle(params, "RX")?; + self.inner.rx(angle, q); + Ok(None) + } + "RY" => { + let angle = crate::extract_angle(params, "RY")?; + self.inner.ry(angle, q); + Ok(None) + } + "RZ" => { + let angle = crate::extract_angle(params, "RZ")?; + self.inner.rz(angle, q); + Ok(None) + } + "T" => { + self.inner.rz(Angle64::QUARTER_TURN / 2u64, q); + Ok(None) + } + "Tdg" => { + self.inner.rz(-(Angle64::QUARTER_TURN / 2u64), q); + Ok(None) + } + "PZ" | "Init" | "init |0>" => { + self.inner.pz(QubitId(location)); + Ok(None) + } + "PX" | "Init +X" | "init |+>" => { + self.inner.px(QubitId(location)); + Ok(None) + } + "MZ" | "Measure" | "measure Z" => { + let result = self + .inner + .mz(q) + .into_iter() + .next() + .expect("measurement returned no results"); + Ok(Some(u8::from(result.outcome))) + } + _ => Err(PyErr::new::(format!( + "Unsupported single-qubit gate: {symbol}" + ))), + } + } + + #[pyo3(signature = (symbol, location, params=None))] + fn run_2q_gate( + &mut self, + symbol: &str, + location: &Bound<'_, PyTuple>, + params: Option<&Bound<'_, PyDict>>, + ) -> PyResult> { + if location.len() != 2 { + return Err(PyErr::new::( + "Two-qubit gate requires exactly 2 qubit locations", + )); + } + let q1: usize = location.get_item(0)?.extract()?; + let q2: usize = location.get_item(1)?.extract()?; + self.check_qubit(q1, symbol)?; + self.check_qubit(q2, symbol)?; + let pair = &[(QubitId(q1), QubitId(q2))]; + match symbol { + "CX" | "CNOT" => { + self.inner.cx(pair); + Ok(None) + } + "CY" => { + self.inner.cy(pair); + Ok(None) + } + "CZ" => { + self.inner.cz(pair); + Ok(None) + } + "SXX" => { + self.inner.sxx(pair); + Ok(None) + } + "SXXdg" => { + self.inner.sxxdg(pair); + Ok(None) + } + "SYY" => { + self.inner.syy(pair); + Ok(None) + } + "SYYdg" => { + self.inner.syydg(pair); + Ok(None) + } + "SZZ" => { + self.inner.szz(pair); + Ok(None) + } + "SZZdg" => { + self.inner.szzdg(pair); + Ok(None) + } + "SWAP" => { + self.inner.swap(pair); + Ok(None) + } + "RZZ" => { + let angle = crate::extract_angle(params, "RZZ")?; + self.inner.rzz(angle, pair); + Ok(None) + } + _ => Err(PyErr::new::(format!( + "Unsupported two-qubit gate: {symbol}" + ))), + } + } + + #[pyo3(signature = (symbol, locations, **params))] + fn run_gate( + &mut self, + symbol: &str, + locations: &Bound<'_, PyAny>, + params: Option<&Bound<'_, PyDict>>, + py: Python<'_>, + ) -> PyResult> { + let output = PyDict::new(py); + let locations_set: Bound = locations.clone().cast_into()?; + for location in locations_set.iter() { + let loc_tuple: Bound<'_, PyTuple> = if location.is_instance_of::() { + location.clone().cast_into()? + } else { + PyTuple::new(py, std::slice::from_ref(&location))? + }; + let result = match loc_tuple.len() { + 1 => { + let qubit: usize = loc_tuple.get_item(0)?.extract()?; + self.run_1q_gate(symbol, qubit, params)? + } + 2 => self.run_2q_gate(symbol, &loc_tuple, params)?, + _ => { + return Err(PyErr::new::( + "Gate location must be 1 or 2 qubits", + )); + } + }; + if let Some(value) = result { + output.set_item(location, value)?; + } + } + Ok(output.into()) + } +} diff --git a/python/pecos-rslib-exp/src/stabmps_builder.rs b/python/pecos-rslib-exp/src/stabmps_builder.rs new file mode 100644 index 000000000..b4cf0a044 --- /dev/null +++ b/python/pecos-rslib-exp/src/stabmps_builder.rs @@ -0,0 +1,119 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! `StabMps` backend for `sim_neo`. +//! +//! Provides a `SimulatorFactory` implementation that creates `StabMps` simulators +//! with configurable parameters (`lazy_measure`, `max_bond_dim`, etc.). + +use pecos_neo::noise::ComposableNoiseModel; +use pecos_neo::program::{DynProgramRunner, ProgramRunner}; +use pecos_neo::tool::SimulatorFactory; +use pecos_stab_tn::stab_mps::StabMps; + +/// Configuration for the `StabMps` backend. +/// +/// Carries simulator parameters through the builder-of-builders pattern. +/// Implements `SimulatorFactory` so it can be used with `custom_backend()`. +#[derive(Debug, Clone)] +pub struct StabMpsBuilder { + /// Use lazy measurement (correct for non-Clifford, slower). + pub lazy_measure: bool, + /// Maximum MPS bond dimension. + pub max_bond_dim: usize, + /// Maximum truncation error for MPS compression. + /// None = disabled (library default, use fixed bond dim cap only). + pub max_truncation_error: Option, + /// Merge consecutive RZ on same qubit before decomposition. + pub merge_rz: bool, +} + +impl Default for StabMpsBuilder { + fn default() -> Self { + Self { + lazy_measure: false, + max_bond_dim: 64, + max_truncation_error: None, + merge_rz: false, + } + } +} + +impl StabMpsBuilder { + /// Create with default settings. + #[must_use] + pub fn new() -> Self { + Self::default() + } + + /// Enable lazy measurement (correct for non-Clifford states). + #[must_use] + pub fn with_lazy_measure(mut self, lazy: bool) -> Self { + self.lazy_measure = lazy; + self + } + + /// Set maximum bond dimension. + #[must_use] + pub fn with_max_bond_dim(mut self, bd: usize) -> Self { + self.max_bond_dim = bd; + self + } + + /// Set maximum truncation error. + #[must_use] + pub fn with_max_truncation_error(mut self, err: f64) -> Self { + self.max_truncation_error = Some(err); + self + } + + /// Enable RZ merging. + #[must_use] + pub fn with_merge_rz(mut self, merge: bool) -> Self { + self.merge_rz = merge; + self + } +} + +impl SimulatorFactory for StabMpsBuilder { + fn create_runner( + &self, + num_qubits: usize, + noise: Option, + seed: Option, + ) -> Box { + let mut builder = StabMps::builder(num_qubits); + if self.lazy_measure { + builder = builder.lazy_measure(true); + } + builder = builder.max_bond_dim(self.max_bond_dim); + if let Some(err) = self.max_truncation_error { + builder = builder.max_truncation_error(err); + } + if self.merge_rz { + builder = builder.merge_rz(true); + } + if let Some(s) = seed { + builder = builder.seed(s); + } + let sim = builder.build(); + + let mut runner = ProgramRunner::rotations(sim); + if let Some(n) = noise { + runner = runner.with_noise(n); + } + if let Some(s) = seed { + runner = runner.with_seed(s); + } + Box::new(runner) + } +} diff --git a/python/pecos-rslib-exp/uv.lock b/python/pecos-rslib-exp/uv.lock new file mode 100644 index 000000000..4402a99f6 --- /dev/null +++ b/python/pecos-rslib-exp/uv.lock @@ -0,0 +1,8 @@ +version = 1 +revision = 3 +requires-python = ">=3.10" + +[[package]] +name = "pecos-rslib-exp" +version = "0.2.0.dev0" +source = { editable = "." } diff --git a/python/pecos-rslib-llvm/pyproject.toml b/python/pecos-rslib-llvm/pyproject.toml index 949203232..de6566bad 100644 --- a/python/pecos-rslib-llvm/pyproject.toml +++ b/python/pecos-rslib-llvm/pyproject.toml @@ -30,7 +30,7 @@ classifiers = [ ] [build-system] -requires = ["maturin>=1.2,<2.0"] +requires = ["maturin>=1.13.1,<2.0"] build-backend = "maturin" [tool.maturin] @@ -39,7 +39,7 @@ module-name = "pecos_rslib_llvm" [dependency-groups] dev = [] test = [ - "pytest>=7.0", + "pytest>=9.0", ] [tool.uv.sources] diff --git a/python/pecos-rslib/Cargo.toml b/python/pecos-rslib/Cargo.toml index fe1c44197..5d2ff85f6 100644 --- a/python/pecos-rslib/Cargo.toml +++ b/python/pecos-rslib/Cargo.toml @@ -62,6 +62,7 @@ pecos-experimental.workspace = true # Third-party pyo3 = { workspace = true, features = ["extension-module", "abi3-py310", "generate-import-lib", "num-complex"] } +rayon.workspace = true rand.workspace = true ndarray.workspace = true num-complex.workspace = true diff --git a/python/pecos-rslib/pecos_rslib.pyi b/python/pecos-rslib/pecos_rslib.pyi index 2cbaad411..f949198c5 100644 --- a/python/pecos-rslib/pecos_rslib.pyi +++ b/python/pecos-rslib/pecos_rslib.pyi @@ -833,8 +833,8 @@ class Stabilizer: @property def num_qubits(self) -> int: ... -class CliffordRz: - """Rust Clifford+RZ simulator.""" +class StabVec: + """Rust Clifford+RZ simulator (stabilizer sum / StabVec).""" def __init__( self, @@ -939,8 +939,8 @@ class StabilizerEngineBuilder: ... -class CliffordRzEngineBuilder: - """Builder for Clifford+RZ engines.""" +class StabVecEngineBuilder: + """Builder for StabVec (Clifford+RZ) engines.""" ... @@ -1237,13 +1237,13 @@ class quantum: state_vector: Callable[..., StateVectorEngineBuilder] sparse_stab: Callable[..., SparseStabEngineBuilder] stabilizer: Callable[..., StabilizerEngineBuilder] - clifford_rz: Callable[..., CliffordRzEngineBuilder] + stab_vec: Callable[..., StabVecEngineBuilder] density_matrix: Callable[..., DensityMatrixEngineBuilder] coin_toss: Callable[..., CoinTossEngineBuilder] StateVectorEngineBuilder: type[StateVectorEngineBuilder] SparseStabEngineBuilder: type[SparseStabEngineBuilder] StabilizerEngineBuilder: type[StabilizerEngineBuilder] - CliffordRzEngineBuilder: type[CliffordRzEngineBuilder] + StabVecEngineBuilder: type[StabVecEngineBuilder] DensityMatrixEngineBuilder: type[DensityMatrixEngineBuilder] CoinTossEngineBuilder: type[CoinTossEngineBuilder] @@ -1272,6 +1272,10 @@ def qis_engine(**kwargs: object) -> QisEngineBuilder: """Create a QIS engine builder.""" ... +def selene_engine(**kwargs: object) -> QisEngineBuilder: + """Create a QIS engine builder configured with the Selene runtime.""" + ... + def phir_json_engine(**kwargs: object) -> PhirJsonEngineBuilder: """Create a PHIR JSON engine builder.""" ... @@ -1288,8 +1292,8 @@ def stabilizer(**kwargs: object) -> StabilizerEngineBuilder: """Create a stabilizer engine builder.""" ... -def clifford_rz(**kwargs: object) -> CliffordRzEngineBuilder: - """Create a Clifford+RZ engine builder.""" +def stab_vec(**kwargs: object) -> StabVecEngineBuilder: + """Create a StabVec (Clifford+RZ) engine builder.""" ... def density_matrix(**kwargs: object) -> DensityMatrixEngineBuilder: diff --git a/python/pecos-rslib/pyproject.toml b/python/pecos-rslib/pyproject.toml index afb12ad8b..2f45395d6 100644 --- a/python/pecos-rslib/pyproject.toml +++ b/python/pecos-rslib/pyproject.toml @@ -30,7 +30,7 @@ classifiers = [ ] [build-system] -requires = ["maturin>=1.2,<2.0"] +requires = ["maturin>=1.13.1,<2.0"] build-backend = "maturin" [tool.maturin] @@ -41,7 +41,7 @@ dev = [ "patchelf; platform_system != 'Windows'", # For setting rpath in shared libraries during development (Linux/macOS only) ] test = [ - "pytest>=7.0", + "pytest>=9.0", ] numpy-compat = [ # NumPy/SciPy compatibility tests "numpy>=1.20", diff --git a/python/pecos-rslib/src/bit_int_bindings.rs b/python/pecos-rslib/src/bit_int_bindings.rs index 167c50691..1ed2f5b31 100644 --- a/python/pecos-rslib/src/bit_int_bindings.rs +++ b/python/pecos-rslib/src/bit_int_bindings.rs @@ -524,7 +524,7 @@ impl PyBitInt { } pub fn __repr__(&self) -> String { - format!("BitInt({}, 0b{})", self.inner.size(), self.inner,) + format!("BitInt({}, 0b{})", self.inner.size(), self.inner) } #[pyo3(signature = (reverse_bits=false, separator=None))] diff --git a/python/pecos-rslib/src/bit_uint_bindings.rs b/python/pecos-rslib/src/bit_uint_bindings.rs index b0dac4a08..b4590ecdb 100644 --- a/python/pecos-rslib/src/bit_uint_bindings.rs +++ b/python/pecos-rslib/src/bit_uint_bindings.rs @@ -507,7 +507,7 @@ impl PyBitUInt { } pub fn __repr__(&self) -> String { - format!("BitUInt({}, 0b{})", self.inner.size(), self.inner,) + format!("BitUInt({}, 0b{})", self.inner.size(), self.inner) } #[pyo3(signature = (reverse_bits=false, separator=None))] diff --git a/python/pecos-rslib/src/dag_circuit_bindings.rs b/python/pecos-rslib/src/dag_circuit_bindings.rs index 02ea7062b..466260ad8 100644 --- a/python/pecos-rslib/src/dag_circuit_bindings.rs +++ b/python/pecos-rslib/src/dag_circuit_bindings.rs @@ -28,7 +28,6 @@ use pecos_core::{Angle64, GateQubits, GateSignature, TimeUnits}; use pecos_quantum::{Attribute, DagCircuit, Gate, GateType, QubitId, Tick, TickCircuit}; use pyo3::prelude::*; use pyo3::types::{PyBytes, PyDict, PyList}; -use std::collections::HashMap; /// Convert a Rust Attribute to a Python object. fn attribute_to_py(py: Python<'_>, attr: &Attribute) -> Py { @@ -619,6 +618,12 @@ impl PyGate { self.inner.qubits.iter().map(|q| usize::from(*q)).collect() } + /// Measurement result identities (one per qubit for measurement gates, empty otherwise). + #[getter] + fn meas_ids(&self) -> Vec { + self.inner.meas_ids.iter().map(|mr| mr.0).collect() + } + /// Check if this is a single-qubit gate. fn is_single_qubit(&self) -> bool { self.inner.is_single_qubit() @@ -866,6 +871,27 @@ pyo3::create_exception!( pyo3::exceptions::PyException ); +/// Extract node indices from a list of either `int` or `(int, int)` tuples. +/// This allows `detector()` / `observable()` to accept both raw node indices +/// and measurement refs from `mz()`. +fn extract_measurement_nodes(list: &Bound<'_, pyo3::types::PyList>) -> PyResult> { + list.iter() + .map(|item| { + // Try (node, qubit) tuple first + if let Ok((node, _qubit)) = item.extract::<(usize, usize)>() { + Ok(node) + } else { + // Fall back to plain int + item.extract::().map_err(|_| { + pyo3::exceptions::PyTypeError::new_err( + "measurements must be a list of ints or (node, qubit) tuples from mz()", + ) + }) + } + }) + .collect() +} + /// Python wrapper for `DagCircuit`. /// /// A directed acyclic graph representation of a quantum circuit where nodes are gates @@ -1246,11 +1272,16 @@ impl PyDagCircuit { /// Measure qubits in the Z basis. /// - /// Note: Unlike gates, measurements break the chain in simulators. - /// This method still returns self for convenience in Python. - fn mz(slf: Py, py: Python<'_>, qubits: Vec) -> Py { - slf.borrow_mut(py).inner.mz(&qubits); - slf + /// Returns a list of `(node, qubit)` tuples that can be passed to + /// `detector()` and `observable()`. + /// + /// Example: + /// >>> dag = `DagCircuit()` + /// >>> ms = dag.mz([0, 1]) + /// >>> dag.detector(ms) + fn mz(slf: &Bound<'_, Self>, qubits: Vec) -> Vec<(usize, usize)> { + let refs = slf.borrow_mut().inner.mz(&qubits); + refs.iter().map(|r| (r.node, r.qubit.index())).collect() } /// Measure and free qubits (destructive measurement). @@ -1277,6 +1308,113 @@ impl PyDagCircuit { slf } + // ==================== Annotations ==================== + + /// Annotate a detector: measurements whose XOR should be deterministic. + /// + /// Args: + /// measurements: List of measurement refs from `mz()` (tuples of + /// `(node, qubit)`), or plain node indices. + /// label: Optional label string. + /// + /// Returns: + /// The annotation index. + /// + /// Example: + /// >>> ms = dag.mz([0, 1]) + /// >>> dag.detector(ms, `label="Z_0` `Z_1`") + #[pyo3(signature = (measurements, label=None))] + fn detector( + &mut self, + measurements: &Bound<'_, pyo3::types::PyList>, + label: Option, + ) -> PyResult { + let nodes = extract_measurement_nodes(measurements)?; + Ok(if let Some(l) = label { + self.inner.detector_labeled(&l, &nodes) + } else { + self.inner.detector(&nodes) + }) + } + + /// Annotate a logical observable: measurements whose XOR gives a logical outcome. + /// + /// Args: + /// measurements: List of measurement refs from `mz()` (tuples of + /// `(node, qubit)`), or plain node indices. + /// label: Optional label string. + /// + /// Returns: + /// The annotation index. + #[pyo3(signature = (measurements, label=None))] + fn observable( + &mut self, + measurements: &Bound<'_, pyo3::types::PyList>, + label: Option, + ) -> PyResult { + let nodes = extract_measurement_nodes(measurements)?; + Ok(if let Some(l) = label { + self.inner.observable_labeled(&l, &nodes) + } else { + self.inner.observable(&nodes) + }) + } + + /// Place a Pauli operator annotation at this point in the circuit. + /// + /// Only faults BEFORE this annotation can flip the operator. + /// Accepts a `PauliString`, which supports `PauliString.X(0) & PauliString.Z(1)`. + /// + /// Args: + /// pauli: A `PauliString` to track. + /// label: Optional label string. + /// + /// Returns: + /// The annotation index. + /// + /// Example: + /// >>> from pecos import `PauliString` + /// >>> `dag.pauli_operator(PauliString.Z(0)` & PauliString.Z(1)) + #[pyo3(signature = (pauli, label=None))] + fn pauli_operator( + &mut self, + pauli: &crate::pauli_bindings::PauliString, + label: Option, + ) -> usize { + if let Some(l) = label { + self.inner.pauli_operator_labeled(&l, pauli.inner.clone()) + } else { + self.inner.pauli_operator(pauli.inner.clone()) + } + } + + /// Get all annotations as a list of dicts. + /// + /// Each dict has keys: "pauli" (`PauliString`), "kind" (str), "label" (str or None). + fn annotations(&self, py: Python<'_>) -> PyResult> { + let list = pyo3::types::PyList::empty(py); + + for ann in self.inner.annotations() { + let dict = pyo3::types::PyDict::new(py); + let ps = crate::pauli_bindings::PauliString { + inner: ann.pauli.clone(), + }; + dict.set_item("pauli", ps.into_pyobject(py)?)?; + let kind_str = match &ann.kind { + pecos_quantum::AnnotationKind::Detector { .. } => "detector", + pecos_quantum::AnnotationKind::Observable { .. } => "observable", + pecos_quantum::AnnotationKind::Operator => "operator", + }; + dict.set_item("kind", kind_str)?; + dict.set_item("label", &ann.label)?; + list.append(dict)?; + } + + Ok(list.unbind()) + } + + // ==================== Metadata ==================== + /// Add metadata to the last added gate. /// /// Args: @@ -1947,7 +2085,8 @@ impl PyTick { /// Use `tick()` to create a new tick and get a handle for adding gates. #[pyclass(name = "TickCircuit", module = "pecos_rslib.quantum")] pub struct PyTickCircuit { - inner: TickCircuit, + /// The underlying Rust TickCircuit. + pub inner: TickCircuit, } #[pymethods] @@ -2274,6 +2413,60 @@ impl PyTickCircuit { } } + /// Lower Clifford-angle rotations to named Clifford gates. + /// + /// Replaces parameterized rotations at Clifford angles with their named + /// equivalents: RZ(pi/2) -> SZ, RZ(pi) -> Z, RX(pi/2) -> SX, etc. + /// + /// Use this on circuits from QIS trace (Guppy/Selene) that use + /// parameterized gates even for Clifford operations. Without this, + /// stabilizer simulators may reject the circuit. + /// + /// Modifies the circuit in place. + fn lower_clifford_rotations(&mut self) { + use pecos_quantum::pass::{CircuitPass, SimplifyRotations}; + SimplifyRotations.apply_tick(&mut self.inner); + } + + /// Assign MeasId to measurement gates that don't have them. + /// + /// Use on circuits from external sources (QIS trace, Stim import) + /// that don't assign MeasId during construction. + fn assign_missing_meas_ids(&mut self) { + use pecos_quantum::pass::{AssignMissingMeasIds, CircuitPass}; + AssignMissingMeasIds.apply_tick(&mut self.inner); + } + + /// Insert Idle gates after each two-qubit gate on both of its qubits. + /// + /// Models idle noise during two-qubit gate execution. The noise model + /// applies RZ(p_idle * duration) when it encounters an Idle gate. + /// + /// Args: + /// duration: Idle time in abstract time units (default: 1.0). + #[pyo3(signature = (duration=1.0))] + fn insert_idle_after_two_qubit_gates(&mut self, duration: f64) { + self.inner.insert_idle_after_two_qubit_gates(duration); + } + + /// Insert identity gates for qubits not operated on during each tick. + /// + /// For each tick, qubits not involved in any gate get an identity (I) + /// gate that receives `p1` noise. This matches Stim's convention of + /// `DEPOLARIZE1` on idle qubits between ticks. + fn fill_idle_gates(&mut self) { + self.inner.fill_idle_gates(); + } + + /// Compact ticks by merging gates into earlier ticks when possible. + /// + /// ASAP scheduling: gates that don't share qubits are merged into the + /// same tick. Useful after replaying a serialized trace where each + /// gate got its own tick. + fn compact_ticks(&mut self) { + self.inner.compact_ticks(); + } + // --- Gate signature validation --- /// Import gate signatures for validation. @@ -2281,7 +2474,7 @@ impl PyTickCircuit { /// Args: /// sigs: A dictionary mapping gate names to (`quantum_arity`, `angle_arity`) tuples. fn import_gate_signatures(&mut self, sigs: &Bound<'_, PyDict>) -> PyResult<()> { - let mut sig_map = HashMap::new(); + let mut sig_map = std::collections::BTreeMap::new(); for (key, value) in sigs.iter() { let name: String = key.extract()?; let (quantum_arity, angle_arity): (usize, usize) = value.extract()?; @@ -2314,7 +2507,8 @@ impl PyTickCircuit { /// Extracts signatures from all registered gates and imports them /// for validation when adding custom gates. fn import_registry(&mut self, registry: &PyGateRegistry) { - let sigs = registry.inner.signatures(); + let sigs: std::collections::BTreeMap<_, _> = + registry.inner.signatures().into_iter().collect(); self.inner.import_signatures(&sigs); } @@ -2325,6 +2519,97 @@ impl PyTickCircuit { self.inner.gate_count() ) } + + // ==================== Annotations ==================== + + /// Annotate a detector: measurements whose XOR should be deterministic. + #[pyo3(signature = (measurements, label=None))] + fn detector( + &mut self, + measurements: &Bound<'_, pyo3::types::PyList>, + label: Option, + ) -> PyResult { + let refs = extract_tick_meas_refs(measurements)?; + let idx = if let Some(l) = label { + self.inner.detector_labeled(&l, &refs) + } else { + self.inner.detector(&refs) + }; + Ok(idx) + } + + /// Annotate a logical observable. + #[pyo3(signature = (measurements, label=None))] + fn observable( + &mut self, + measurements: &Bound<'_, pyo3::types::PyList>, + label: Option, + ) -> PyResult { + let refs = extract_tick_meas_refs(measurements)?; + let idx = if let Some(l) = label { + self.inner.observable_labeled(&l, &refs) + } else { + self.inner.observable(&refs) + }; + Ok(idx) + } + + /// Place a Pauli operator annotation. + #[pyo3(signature = (pauli, label=None))] + fn pauli_operator( + &mut self, + pauli: &crate::pauli_bindings::PauliString, + label: Option, + ) -> usize { + if let Some(l) = label { + self.inner.pauli_operator_labeled(&l, pauli.inner.clone()) + } else { + self.inner.pauli_operator(pauli.inner.clone()) + } + } + + /// Get all annotations. + fn annotations(&self, py: Python<'_>) -> PyResult> { + let list = pyo3::types::PyList::empty(py); + for ann in self.inner.annotations() { + let dict = pyo3::types::PyDict::new(py); + let ps = crate::pauli_bindings::PauliString { + inner: ann.pauli.clone(), + }; + dict.set_item("pauli", ps.into_pyobject(py)?)?; + let kind_str = match &ann.kind { + pecos_quantum::AnnotationKind::Detector { .. } => "detector", + pecos_quantum::AnnotationKind::Observable { .. } => "observable", + pecos_quantum::AnnotationKind::Operator => "operator", + }; + dict.set_item("kind", kind_str)?; + dict.set_item("label", &ann.label)?; + list.append(dict)?; + } + Ok(list.unbind()) + } +} + +/// Extract `TickMeasRef` from Python list of `(tick, gate_idx, qubit)` tuples. +fn extract_tick_meas_refs( + list: &Bound<'_, pyo3::types::PyList>, +) -> PyResult> { + list.iter() + .map(|item| { + let (tick, gate_idx, qubit): (usize, usize, usize) = item.extract().map_err(|_| { + pyo3::exceptions::PyTypeError::new_err( + "measurements must be (tick, gate_idx, qubit) tuples from mz()", + ) + })?; + Ok(pecos_quantum::TickMeasRef { + tick, + gate_idx, + qubit: pecos_core::QubitId::from(qubit), + record_idx: 0, // Populated by TickCircuit; placeholder for external construction + meas_id: pecos_core::MeasId(0), // Placeholder + }) + }) + .collect() } /// Handle to a specific tick for adding gates. @@ -3083,35 +3368,91 @@ impl PyTickHandle { /// Measure qubits in the Z basis. /// - /// Returns a `TickMeasureHandle` that allows attaching metadata via `.meta()`. - /// This breaks the chain - only `.meta()` can be called on the result. - fn mz(slf: Py, py: Python<'_>, qubits: Vec) -> PyResult { - let (circuit, tick_idx, gate_idx) = { - let mut handle = slf.borrow_mut(py); - let gate_idx = handle.add_gate_get_idx(py, Gate::mz(&qubits))?; - (handle.circuit.clone_ref(py), handle.tick_idx, gate_idx) - }; - Ok(PyTickMeasureHandle { - circuit, - tick_idx, - gate_idx, - }) + /// Returns a list of `(tick, gate_idx, qubit)` measurement refs + /// for use in `detector()` and `observable()` annotations. + fn mz( + slf: Py, + py: Python<'_>, + qubits: Vec, + ) -> PyResult> { + let mut handle = slf.borrow_mut(py); + let mut gate = Gate::mz(&qubits); + // Assign MeasId values (SSA identity for each measurement) + { + let mut circuit = handle.circuit.borrow_mut(py); + let base = circuit.inner.num_measurements(); + for (i, _) in qubits.iter().enumerate() { + gate.meas_ids.push(pecos_core::MeasId(base + i)); + } + // Increment the measurement counter + circuit.inner.advance_meas_counter(qubits.len()); + } + let gate_idx = handle.add_gate_get_idx(py, gate)?; + let tick_idx = handle.tick_idx; + Ok(qubits.iter().map(|&q| (tick_idx, gate_idx, q)).collect()) + } + + /// Measure qubits with explicit MeasIds. + /// + /// Like ``mz()`` but assigns the given MeasIds instead of auto-assigning. + /// Used when MeasIds flow from an external source (e.g., Guppy result() IDs). + /// + /// The ``meas_ids`` list must have the same length as ``qubits``. + fn mz_with_ids( + slf: Py, + py: Python<'_>, + qubits: Vec, + meas_ids: Vec, + ) -> PyResult> { + if meas_ids.len() != qubits.len() { + return Err(pyo3::exceptions::PyValueError::new_err(format!( + "meas_ids length {} != qubits length {}", + meas_ids.len(), + qubits.len() + ))); + } + let mut handle = slf.borrow_mut(py); + let mut gate = Gate::mz(&qubits); + for &mid in &meas_ids { + gate.meas_ids.push(pecos_core::MeasId(mid)); + } + { + let mut circuit = handle.circuit.borrow_mut(py); + // Advance counter to at least past the highest ID we're assigning + let max_id = meas_ids.iter().copied().max().unwrap_or(0); + let current = circuit.inner.num_measurements(); + if max_id >= current { + circuit.inner.advance_meas_counter(max_id + 1 - current); + } + } + let gate_idx = handle.add_gate_get_idx(py, gate)?; + let tick_idx = handle.tick_idx; + Ok(qubits.iter().map(|&q| (tick_idx, gate_idx, q)).collect()) } /// Measure and free qubits (destructive measurement). /// - /// Returns a `TickMeasureHandle` that allows attaching metadata via `.meta()`. - fn mz_free(slf: Py, py: Python<'_>, qubits: Vec) -> PyResult { - let (circuit, tick_idx, gate_idx) = { - let mut handle = slf.borrow_mut(py); - let gate_idx = handle.add_gate_get_idx(py, Gate::mz_free(&qubits))?; - (handle.circuit.clone_ref(py), handle.tick_idx, gate_idx) - }; - Ok(PyTickMeasureHandle { - circuit, - tick_idx, - gate_idx, - }) + /// Measure and free qubits (destructive measurement). + /// + /// Returns measurement refs for annotations. + fn mz_free( + slf: Py, + py: Python<'_>, + qubits: Vec, + ) -> PyResult> { + let mut handle = slf.borrow_mut(py); + let mut gate = Gate::mz_free(&qubits); + { + let mut circuit = handle.circuit.borrow_mut(py); + let base = circuit.inner.num_measurements(); + for (i, _) in qubits.iter().enumerate() { + gate.meas_ids.push(pecos_core::MeasId(base + i)); + } + circuit.inner.advance_meas_counter(qubits.len()); + } + let gate_idx = handle.add_gate_get_idx(py, gate)?; + let tick_idx = handle.tick_idx; + Ok(qubits.iter().map(|&q| (tick_idx, gate_idx, q)).collect()) } // --- Resource management --- diff --git a/python/pecos-rslib/src/decoder_bindings.rs b/python/pecos-rslib/src/decoder_bindings.rs index 8bee00356..bf9d27879 100644 --- a/python/pecos-rslib/src/decoder_bindings.rs +++ b/python/pecos-rslib/src/decoder_bindings.rs @@ -519,6 +519,50 @@ impl PyPyMatchingDecoder { .map_err(|e| PyErr::new::(e.to_string())) } + /// Decode a batch of syndromes at once. + /// + /// Much faster than calling `decode()` in a Python loop -- the entire batch + /// is processed in Rust with no per-shot Python overhead. + /// + /// # Arguments + /// + /// * `detection_events` - Flattened detection events array (`num_shots` * `num_detectors` bytes) + /// * `num_shots` - Number of shots in the batch + /// + /// # Returns + /// + /// List of observable predictions (one per shot), where each prediction + /// is a list of 0/1 values (one per observable). Use `observables_mask` + /// property on each element or just check index 0 for single-observable codes. + /// + /// # Example + /// + /// ```python + /// # detection_events is shape (num_shots, num_detectors), flattened + /// flat = detection_events.flatten().tolist() + /// predictions = decoder.decode_batch(flat, num_shots=len(detection_events)) + /// num_errors = sum(p[0] != t for p, t in zip(predictions, true_flips)) + /// ``` + fn decode_batch( + &mut self, + detection_events: Vec, + num_shots: usize, + ) -> PyResult>> { + use pecos_decoders::BatchConfig as RustBatchConfig; + + let num_detectors = self.inner.num_detectors(); + let config = RustBatchConfig { + bit_packed_input: false, + bit_packed_output: false, + return_weights: false, + }; + + self.inner + .decode_batch_with_config(&detection_events, num_shots, num_detectors, config) + .map(|result| result.predictions) + .map_err(|e| PyErr::new::(e.to_string())) + } + /// Number of detector nodes in the matching graph. #[getter] fn num_detectors(&self) -> usize { @@ -1452,6 +1496,8 @@ impl PyTesseractResult { #[pyclass(name = "TesseractDecoder", module = "pecos_rslib.decoders", unsendable)] pub struct PyTesseractDecoder { inner: RustTesseractDecoder, + dem_string: String, + config: RustTesseractConfig, } #[pymethods] @@ -1498,8 +1544,13 @@ impl PyTesseractDecoder { } config.verbose = verbose; - RustTesseractDecoder::new(dem, config) - .map(|inner| Self { inner }) + let dem_string = dem.to_string(); + RustTesseractDecoder::new(dem, config.clone()) + .map(|inner| Self { + inner, + dem_string, + config, + }) .map_err(|e| PyErr::new::(e.to_string())) } @@ -1553,6 +1604,82 @@ impl PyTesseractDecoder { self.decode(detections) } + /// Decode a batch of syndromes in parallel using multiple decoder instances. + /// + /// Creates worker decoders on background threads and distributes shots + /// across them. Much faster than sequential decoding for large batches. + /// + /// # Arguments + /// + /// * `syndromes` - List of dense syndrome vectors + /// * `num_workers` - Number of parallel workers (default: number of CPUs) + /// + /// # Returns + /// + /// List of `TesseractResult` in the same order as inputs. + #[pyo3(signature = (syndromes, num_workers=None))] + fn decode_batch( + &self, + syndromes: Vec>, + num_workers: Option, + ) -> PyResult> { + use rayon::prelude::*; + + let n_workers = num_workers.unwrap_or_else(rayon::current_num_threads); + + // Build a thread pool with the requested size + let pool = rayon::ThreadPoolBuilder::new() + .num_threads(n_workers) + .build() + .map_err(|e| PyErr::new::(e.to_string()))?; + + let dem_str = &self.dem_string; + let config = &self.config; + + let results: Result, _> = pool.install(|| { + syndromes + .par_iter() + .map(|syndrome| { + // Each rayon task gets its own thread-local decoder + thread_local! { + static DECODER: std::cell::RefCell> = + const { std::cell::RefCell::new(None) }; + } + + DECODER.with(|cell| { + let mut decoder_ref = cell.borrow_mut(); + if decoder_ref.is_none() { + *decoder_ref = Some( + RustTesseractDecoder::new(dem_str, config.clone()) + .map_err(|e| e.to_string())?, + ); + } + let decoder = decoder_ref.as_mut().unwrap(); + + // Convert dense to sparse + let detections: Vec = syndrome + .iter() + .enumerate() + .filter_map(|(i, &val)| if val != 0 { Some(i as u64) } else { None }) + .collect(); + + let detections_arr = ndarray::Array1::from_vec(detections); + decoder + .decode_detections(&detections_arr.view()) + .map(|r| PyTesseractResult { + observables_mask: r.observables_mask, + cost: r.cost, + low_confidence: r.low_confidence, + }) + .map_err(|e| e.to_string()) + }) + }) + .collect() + }); + + results.map_err(PyErr::new::) + } + /// Number of detectors in the error model. #[getter] fn num_detectors(&self) -> usize { @@ -2036,6 +2163,292 @@ impl PyMinSumBpDecoder { } } +// ============================================================================= +// DEM-Aware Decoder (wraps check-matrix decoders for DEM-level decoding) +// ============================================================================= + +use pecos_decoder_core::DemCheckMatrix; + +/// Decoder type for the DEM-aware wrapper. +enum InnerDecoder { + BpOsd(RustBpOsdDecoder), + BpLsd(RustBpLsdDecoder), + UnionFind(RustUnionFindDecoder), + RelayBp(Box), + MinSumBp(Box), +} + +/// DEM-aware decoder that wraps a check-matrix decoder. +/// +/// Parses a DEM string, extracts the check matrix and observable matrix, +/// creates the inner decoder, and provides `decode_syndrome()` that returns +/// an `observables_mask` -- the same interface as `PyMatching` and Tesseract. +/// +/// # Example +/// +/// ```python +/// from pecos_rslib.decoders import DemAwareDecoder +/// +/// decoder = DemAwareDecoder.from_dem(dem_string, decoder_type="bp_osd") +/// result = decoder.decode_syndrome([0, 1, 1, 0]) +/// print(f"Observable prediction: {result.observables_mask}") +/// ``` +#[pyclass(name = "DemAwareDecoder", module = "pecos_rslib.decoders", unsendable)] +pub struct PyDemAwareDecoder { + inner: InnerDecoder, + dem_check_matrix: DemCheckMatrix, +} + +/// Result from a DEM-aware decoder. +#[pyclass( + name = "DemAwareResult", + module = "pecos_rslib.decoders", + skip_from_py_object +)] +#[derive(Clone)] +pub struct PyDemAwareResult { + /// Bitmask of predicted observable flips. + #[pyo3(get)] + pub observables_mask: u64, + /// Whether the BP decoder converged. + #[pyo3(get)] + pub converged: bool, + /// Number of BP iterations used. + #[pyo3(get)] + pub iterations: usize, +} + +#[pymethods] +impl PyDemAwareResult { + fn __repr__(&self) -> String { + format!( + "DemAwareResult(observables_mask={}, converged={}, iterations={})", + self.observables_mask, self.converged, self.iterations + ) + } +} + +#[pymethods] +impl PyDemAwareDecoder { + /// Create a DEM-aware decoder from a DEM string. + /// + /// # Arguments + /// + /// * `dem` - DEM string in Stim format + /// * `decoder_type` - One of "`bp_osd`", "`bp_lsd`", "`union_find`", "`relay_bp`", "`min_sum_bp`" + /// * `error_rate` - Override error rate for BP priors (default: use DEM probabilities) + /// * `max_iter` - Maximum BP iterations (default: 100) + /// + /// # Example + /// + /// ```python + /// decoder = DemAwareDecoder.from_dem(dem, decoder_type="bp_osd") + /// ``` + #[staticmethod] + #[pyo3(signature = (dem, decoder_type="bp_osd", error_rate=None, max_iter=100))] + fn from_dem( + dem: &str, + decoder_type: &str, + error_rate: Option, + max_iter: usize, + ) -> PyResult { + let dcm = DemCheckMatrix::from_dem_str(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + + if dcm.num_mechanisms == 0 { + return Err(PyErr::new::( + "DEM contains no error mechanisms", + )); + } + + // Error priors: use per-mechanism probabilities from DEM, or uniform override + let priors: Vec = if let Some(p) = error_rate { + vec![p; dcm.num_mechanisms] + } else { + dcm.error_priors.clone() + }; + + // Build the check matrix in the two formats decoders need: + // SparseMatrix for LDPC decoders, Array2 view for Relay/MinSum. + let sparse_h = RustSparseMatrix::from_dense(&dcm.check_matrix.view()); + + let inner = match decoder_type { + "bp_osd" => { + let decoder = RustBpOsdDecoder::new( + &sparse_h, + None, // error_rate + Some(&priors), // error_channel + max_iter, + RustBpMethod::ProductSum, + RustBpSchedule::Parallel, + 1.0, // ms_scaling_factor + RustOsdMethod::Osd0, + 0, // osd_order + RustInputVectorType::Syndrome, + None, + None, + None, + ) + .map_err(|e| PyErr::new::(e.to_string()))?; + InnerDecoder::BpOsd(decoder) + } + "bp_lsd" => { + let decoder = RustBpLsdDecoder::new( + &sparse_h, + None, // error_rate + Some(&priors), // error_channel + max_iter, + RustBpMethod::ProductSum, + RustBpSchedule::Parallel, + 1.0, // ms_scaling_factor + RustOsdMethod::Off, // lsd_method (LSD-0) + 0, // lsd_order + 0, // bits_per_step + RustInputVectorType::Syndrome, + None, + None, + None, + ) + .map_err(|e| PyErr::new::(e.to_string()))?; + InnerDecoder::BpLsd(decoder) + } + "union_find" => { + let decoder = RustUnionFindDecoder::new(&sparse_h, RustUfMethod::Inversion) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + InnerDecoder::UnionFind(decoder) + } + "relay_bp" => { + use pecos_decoders::RelayBpBuilder as RustRelayBpBuilderT; + let h_view = dcm.check_matrix.view(); + let decoder = RustRelayBpBuilderT::new(&h_view) + .error_priors(&priors) + .max_iter(max_iter) + .build() + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + InnerDecoder::RelayBp(Box::new(decoder)) + } + "min_sum_bp" => { + use pecos_decoders::MinSumBpBuilder as RustMinSumBpBuilderT; + let h_view = dcm.check_matrix.view(); + let decoder = RustMinSumBpBuilderT::new(&h_view) + .error_priors(&priors) + .max_iter(max_iter) + .build() + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + InnerDecoder::MinSumBp(Box::new(decoder)) + } + _ => { + return Err(PyErr::new::(format!( + "Unknown decoder type: {decoder_type}. \ + Supported: bp_osd, bp_lsd, union_find, relay_bp, min_sum_bp" + ))); + } + }; + + Ok(Self { + inner, + dem_check_matrix: dcm, + }) + } + + /// Decode a dense syndrome vector. + /// + /// # Arguments + /// + /// * `syndrome` - Dense syndrome vector (0 or 1 for each detector) + /// + /// # Returns + /// + /// `DemAwareResult` with `observables_mask`, `converged`, and `iterations`. + fn decode_syndrome(&mut self, syndrome: Vec) -> PyResult { + let arr = Array1::from_vec(syndrome); + let (decoding, converged, iterations) = match &mut self.inner { + InnerDecoder::BpOsd(d) => { + let r = d.decode(&arr.view()).map_err(|e| { + PyErr::new::(e.to_string()) + })?; + (r.decoding.to_vec(), r.converged, r.iterations) + } + InnerDecoder::BpLsd(d) => { + let r = d.decode(&arr.view()).map_err(|e| { + PyErr::new::(e.to_string()) + })?; + (r.decoding.to_vec(), r.converged, r.iterations) + } + InnerDecoder::UnionFind(d) => { + let r = d.decode(&arr.view(), &[], 0).map_err(|e| { + PyErr::new::(e.to_string()) + })?; + (r.decoding.to_vec(), r.converged, r.iterations) + } + InnerDecoder::RelayBp(d) => { + let r = d.decode(&arr.view()).map_err(|e| { + PyErr::new::(e.to_string()) + })?; + (r.decoding.to_vec(), r.converged, r.iterations) + } + InnerDecoder::MinSumBp(d) => { + let r = d.decode(&arr.view()).map_err(|e| { + PyErr::new::(e.to_string()) + })?; + (r.decoding.to_vec(), r.converged, r.iterations) + } + }; + + let correction: Vec = decoding.iter().map(|&v| v & 1).collect(); + let observables_mask = self + .dem_check_matrix + .observables_mask_from_correction(&correction); + + Ok(PyDemAwareResult { + observables_mask, + converged, + iterations, + }) + } + + /// Number of detectors in the model. + #[getter] + fn num_detectors(&self) -> usize { + self.dem_check_matrix.num_detectors + } + + /// Number of observables in the model. + #[getter] + fn num_observables(&self) -> usize { + self.dem_check_matrix.num_observables + } + + /// Number of error mechanisms in the model. + #[getter] + fn num_mechanisms(&self) -> usize { + self.dem_check_matrix.num_mechanisms + } + + fn __repr__(&self) -> String { + let decoder_name = match &self.inner { + InnerDecoder::BpOsd(_) => "bp_osd", + InnerDecoder::BpLsd(_) => "bp_lsd", + InnerDecoder::UnionFind(_) => "union_find", + InnerDecoder::RelayBp(_) => "relay_bp", + InnerDecoder::MinSumBp(_) => "min_sum_bp", + }; + format!( + "DemAwareDecoder(type={}, detectors={}, mechanisms={}, observables={})", + decoder_name, + self.dem_check_matrix.num_detectors, + self.dem_check_matrix.num_mechanisms, + self.dem_check_matrix.num_observables, + ) + } +} + // ============================================================================= // Module Registration // ============================================================================= @@ -2075,6 +2488,10 @@ pub fn register_decoders_module(parent_module: &Bound<'_, PyModule>) -> PyResult decoders_module.add_class::()?; decoders_module.add_class::()?; + // DEM-aware decoder wrapper + decoders_module.add_class::()?; + decoders_module.add_class::()?; + // Add submodule to parent parent_module.add_submodule(&decoders_module)?; diff --git a/python/pecos-rslib/src/engine_builders.rs b/python/pecos-rslib/src/engine_builders.rs index 7b4e645b7..f18ef6271 100644 --- a/python/pecos-rslib/src/engine_builders.rs +++ b/python/pecos-rslib/src/engine_builders.rs @@ -16,7 +16,7 @@ type RustPhirJsonEngineBuilder = pecos_phir_json::PhirJsonEngineBuilder; type RustHugrEngineBuilder = pecos_hugr::HugrEngineBuilder; type RustPhirEngineBuilder = pecos_phir::PhirEngineBuilder; type RustCoinTossEngineBuilder = CoinTossEngineBuilder; -type RustCliffordRzEngineBuilder = CliffordRzEngineBuilder; +type RustStabVecEngineBuilder = StabVecEngineBuilder; type RustDensityMatrixEngineBuilder = DensityMatrixEngineBuilder; type RustStabilizerEngineBuilder = StabilizerEngineBuilder; type RustSparseStabEngineBuilder = SparseStabEngineBuilder; @@ -176,6 +176,13 @@ impl PyQisEngineBuilder { Ok(self.clone()) } + /// Dump Helios-collected operation chunks to the given directory as JSON. + #[pyo3(signature = (trace_dir))] + fn trace_operations(&mut self, trace_dir: &str) -> PyResult { + self.inner = self.inner.clone().trace_operations_to(trace_dir); + Ok(self.clone()) + } + /// Convert to simulation builder fn to_sim(&self) -> PyResult { Ok(PySimBuilder { @@ -188,6 +195,7 @@ impl PyQisEngineBuilder { explicit_num_qubits: None, keep_intermediate_files: false, hugr_bytes: None, + operation_trace_dir: None, }), }) } @@ -344,6 +352,7 @@ pub struct PyQisControlSimBuilder { pub(crate) explicit_num_qubits: Option, pub(crate) keep_intermediate_files: bool, pub(crate) hugr_bytes: Option>, + pub(crate) operation_trace_dir: Option, } /// Python wrapper for built QIS control simulation @@ -352,6 +361,8 @@ pub struct PyQisControlSimulation { pub(crate) inner: Arc>, /// Path to temp directory containing intermediate files (if `keep_intermediate_files` was true) pub(crate) temp_dir: Option, + /// Path to directory containing operation trace chunks (if enabled) + pub(crate) operation_trace_dir: Option, } #[pymethods] @@ -380,6 +391,12 @@ impl PyQisControlSimulation { self.temp_dir.clone() } + /// Get the operation trace directory (if operation tracing was enabled) + #[getter] + fn operation_trace_dir(&self) -> Option { + self.operation_trace_dir.clone() + } + /// Reset the simulation to its initial state (quantum state back to |0⟩). /// /// Returns the simulation object for method chaining. @@ -731,9 +748,9 @@ pub fn qis_engine() -> PyQisEngineBuilder { } } -/// Create Selene runtime for QIS Control Engine +/// Create a Selene-backed QIS Control Engine builder. #[pyfunction] -pub fn selene_runtime() -> PyResult { +pub fn selene_engine() -> PyResult { let runtime = pecos_qis::selene_simple_runtime().map_err(|e| { PyErr::new::(format!( "Failed to load Selene runtime: {e}" @@ -1415,19 +1432,19 @@ pub fn stabilizer() -> PyStabilizerEngineBuilder { PyStabilizerEngineBuilder::new() } -/// Python wrapper for `CliffordRzEngineBuilder` -#[pyclass(name = "CliffordRzEngineBuilder", from_py_object)] +/// Python wrapper for `StabVecEngineBuilder` +#[pyclass(name = "StabVecEngineBuilder", from_py_object)] #[derive(Clone)] -pub struct PyCliffordRzEngineBuilder { - pub(crate) inner: Option, +pub struct PyStabVecEngineBuilder { + pub(crate) inner: Option, } #[pymethods] -impl PyCliffordRzEngineBuilder { +impl PyStabVecEngineBuilder { #[new] fn new() -> Self { Self { - inner: Some(pecos_engines::clifford_rz()), + inner: Some(pecos_engines::stab_vec()), } } @@ -1448,8 +1465,8 @@ impl PyCliffordRzEngineBuilder { /// Create a Clifford+RZ quantum engine builder #[pyfunction] -pub fn clifford_rz() -> PyCliffordRzEngineBuilder { - PyCliffordRzEngineBuilder::new() +pub fn stab_vec() -> PyStabVecEngineBuilder { + PyStabVecEngineBuilder::new() } /// Python wrapper for `DensityMatrixEngineBuilder` @@ -1596,7 +1613,7 @@ pub fn register_engine_builders(m: &Bound<'_, PyModule>) -> PyResult<()> { // Quantum engine builders m.add_class::()?; m.add_class::()?; - m.add_class::()?; + m.add_class::()?; m.add_class::()?; m.add_class::()?; m.add_class::()?; @@ -1607,7 +1624,7 @@ pub fn register_engine_builders(m: &Bound<'_, PyModule>) -> PyResult<()> { // Engine functions m.add_function(wrap_pyfunction!(self::qasm_engine, m)?)?; m.add_function(wrap_pyfunction!(self::qis_engine, m)?)?; - m.add_function(wrap_pyfunction!(self::selene_runtime, m)?)?; + m.add_function(wrap_pyfunction!(self::selene_engine, m)?)?; m.add_function(wrap_pyfunction!(self::phir_json_engine, m)?)?; m.add_function(wrap_pyfunction!(self::hugr_engine, m)?)?; @@ -1627,7 +1644,7 @@ pub fn register_engine_builders(m: &Bound<'_, PyModule>) -> PyResult<()> { m.add_function(wrap_pyfunction!(self::state_vector, m)?)?; m.add_function(wrap_pyfunction!(self::sparse_stab, m)?)?; m.add_function(wrap_pyfunction!(self::stabilizer, m)?)?; - m.add_function(wrap_pyfunction!(self::clifford_rz, m)?)?; + m.add_function(wrap_pyfunction!(self::stab_vec, m)?)?; m.add_function(wrap_pyfunction!(self::density_matrix, m)?)?; m.add_function(wrap_pyfunction!(self::coin_toss, m)?)?; diff --git a/python/pecos-rslib/src/engines_module.rs b/python/pecos-rslib/src/engines_module.rs index e5faac8bd..b1557b94c 100644 --- a/python/pecos-rslib/src/engines_module.rs +++ b/python/pecos-rslib/src/engines_module.rs @@ -66,8 +66,8 @@ pub fn register_engines_module(parent: &Bound<'_, PyModule>) -> PyResult<()> { parent.getattr("StabilizerEngineBuilder")?, )?; engines.add( - "CliffordRzEngineBuilder", - parent.getattr("CliffordRzEngineBuilder")?, + "StabVecEngineBuilder", + parent.getattr("StabVecEngineBuilder")?, )?; engines.add( "DensityMatrixEngineBuilder", diff --git a/python/pecos-rslib/src/fault_tolerance_bindings.rs b/python/pecos-rslib/src/fault_tolerance_bindings.rs index 401b7eb66..446479fe7 100644 --- a/python/pecos-rslib/src/fault_tolerance_bindings.rs +++ b/python/pecos-rslib/src/fault_tolerance_bindings.rs @@ -43,10 +43,17 @@ //! ``` use pecos_qec::fault_tolerance::dem_builder::{ - ComparisonMethod as RustComparisonMethod, DemBuilder as RustDemBuilder, - DetectorErrorModel as RustDetectorErrorModel, EquivalenceResult as RustEquivalenceResult, - MeasurementNoiseModel as RustMeasurementNoiseModel, MemBuilder as RustMemBuilder, - ParsedDem as RustParsedDem, compare_dems_exact as rust_compare_dems_exact, + ComparisonMethod as RustComparisonMethod, + ContributionEffectSummary as RustContributionEffectSummary, + ContributionRenderRecord as RustContributionRenderRecord, + ContributionRenderStrategy as RustContributionRenderStrategy, + ContributionRenderSummary as RustContributionRenderSummary, DemBuilder as RustDemBuilder, + DemSampler as RustNewDemSampler, DemSamplerBuilder as RustNewDemSamplerBuilder, + DetectorErrorModel as RustDetectorErrorModel, DirectSourceFamily as RustDirectSourceFamily, + EquivalenceResult as RustEquivalenceResult, FaultContribution as RustFaultContribution, + FaultSourceType as RustFaultSourceType, NoiseConfig, ParsedDem as RustParsedDem, + TwoDetectorDirectRenderPolicy as RustTwoDetectorDirectRenderPolicy, + compare_dems_exact as rust_compare_dems_exact, compare_dems_statistical as rust_compare_dems_statistical, verify_dem_equivalence as rust_verify_dem_equivalence, }; @@ -56,13 +63,13 @@ use pecos_qec::fault_tolerance::propagator::{ DagSpacetimeLocation, Pauli, }; use pecos_quantum::DagCircuit; +use pecos_quantum::QubitId; use pyo3::Py; use pyo3::prelude::*; -/// Type alias for batch sampling results: (`detection_events_per_shot`, `observable_flips_per_shot`) -type BatchSampleResult = (Vec>, Vec>); - -// --- Fault Location Types --- +// ============================================================================= +// Fault Location Types +// ============================================================================= /// A spacetime location for a fault in a DAG circuit. /// @@ -127,18 +134,20 @@ impl From<&DagSpacetimeLocation> for PyFaultLocation { fn from(loc: &DagSpacetimeLocation) -> Self { Self { node: loc.node, - qubits: loc.qubits.iter().map(pecos_core::QubitId::index).collect(), + qubits: loc.qubits.iter().map(QubitId::index).collect(), before: loc.before, gate_type: format!("{:?}", loc.gate_type), } } } -// --- Fault Influence Map --- +// ============================================================================= +// Fault Influence Map +// ============================================================================= /// A fault influence map built from a DAG circuit. /// -/// Maps fault locations to their effects on detectors and logical observables. +/// Maps fault locations to their effects on detectors and DEM outputs. /// Uses CSR (Compressed Sparse Row) layout for cache-efficient storage. /// /// This is functionally equivalent to a Detector Error Model (DEM) but stored @@ -151,7 +160,7 @@ impl From<&DagSpacetimeLocation> for PyFaultLocation { /// influence_map = analyzer.build_influence_map() /// /// # Query fault influence -/// has_syndrome, causes_logical = influence_map.classify_fault(loc_idx=0, pauli=1) +/// has_syndrome, flips_dem_output = influence_map.classify_fault(loc_idx=0, pauli=1) /// /// # Get detector indices flipped by this fault /// detector_indices = influence_map.get_detector_indices(loc_idx=0, pauli=1) @@ -175,13 +184,22 @@ impl PyDagFaultInfluenceMap { self.inner.detectors.len() } - /// Number of logical observables tracked. + /// Total number of outputs in the DEM `L` namespace. #[getter] - fn num_logicals(&self) -> usize { - self.inner - .influences - .max_logical_index() - .map_or(0, |i| i + 1) + fn num_dem_outputs(&self) -> usize { + self.inner.num_dem_outputs() + } + + /// Number of observable DEM outputs. + #[getter] + fn num_observables(&self) -> usize { + self.inner.num_observables() + } + + /// Number of tracked operators. + #[getter] + fn num_tracked_ops(&self) -> usize { + self.inner.num_tracked_ops() } /// Get all fault locations. @@ -214,11 +232,16 @@ impl PyDagFaultInfluenceMap { /// pauli: Pauli type (1=X, 2=Y, 3=Z). /// /// Returns: - /// Tuple (`has_syndrome`, `causes_logical_error`). + /// Tuple (`has_syndrome`, `flips_dem_output`). /// - `has_syndrome`: True if the fault flips at least one detector. - /// - `causes_logical_error`: True if the fault flips the logical observable. + /// - `flips_dem_output`: True if the fault flips at least one standard observable DEM output. fn classify_fault(&self, loc_idx: usize, pauli: u8) -> (bool, bool) { - self.inner.classify_fault(loc_idx, pauli) + ( + self.inner + .influences + .has_detector_flips(loc_idx, Pauli::from_u8(pauli)), + self.inner.has_observable_flips(loc_idx, pauli), + ) } /// Get detector indices flipped by a fault. @@ -233,16 +256,36 @@ impl PyDagFaultInfluenceMap { self.inner.get_detector_indices(loc_idx, pauli).to_vec() } - /// Get logical indices flipped by a fault. + /// Get standard DEM `L` observable indices flipped by a fault. + fn get_dem_output_indices(&self, loc_idx: usize, pauli: u8) -> Vec { + self.inner.get_observable_indices(loc_idx, pauli) + } + + /// Get raw internal non-detector influence indices flipped by a fault. + /// + /// These are implementation indices used to propagate both observables and + /// tracked operators. Prefer `get_dem_output_indices`, + /// `get_observable_indices`, or `get_tracked_op_indices` for public DEM + /// semantics. + fn get_internal_dem_output_indices(&self, loc_idx: usize, pauli: u8) -> Vec { + self.inner.get_dem_output_indices(loc_idx, pauli).to_vec() + } + + /// Get tracked-operator indices flipped by a fault. /// /// Args: /// `loc_idx`: Location index. /// pauli: Pauli type (1=X, 2=Y, 3=Z). /// /// Returns: - /// List of logical indices that are flipped by this fault. - fn get_logical_indices(&self, loc_idx: usize, pauli: u8) -> Vec { - self.inner.get_logical_indices(loc_idx, pauli).to_vec() + /// List of tracked-operator indices that are flipped by this fault. + fn get_tracked_op_indices(&self, loc_idx: usize, pauli: u8) -> Vec { + self.inner.get_tracked_op_indices(loc_idx, pauli) + } + + /// Get observable indices flipped by a fault. + fn get_observable_indices(&self, loc_idx: usize, pauli: u8) -> Vec { + self.inner.get_observable_indices(loc_idx, pauli) } /// Check if a fault at the given location flips any detector. @@ -259,18 +302,26 @@ impl PyDagFaultInfluenceMap { .has_detector_flips(loc_idx, Pauli::from_u8(pauli)) } - /// Check if a fault at the given location flips a logical observable. + /// Check if a fault at the given location flips any standard DEM output. + fn has_dem_output_flips(&self, loc_idx: usize, pauli: u8) -> bool { + self.inner.has_observable_flips(loc_idx, pauli) + } + + /// Check if a fault at the given location flips any observable. + fn has_observable_flips(&self, loc_idx: usize, pauli: u8) -> bool { + self.inner.has_observable_flips(loc_idx, pauli) + } + + /// Check if a fault at the given location flips any tracked op. /// /// Args: /// `loc_idx`: Location index. /// pauli: Pauli type (1=X, 2=Y, 3=Z). /// /// Returns: - /// True if the fault flips the logical observable. - fn has_logical_flips(&self, loc_idx: usize, pauli: u8) -> bool { - self.inner - .influences - .has_logical_flips(loc_idx, Pauli::from_u8(pauli)) + /// True if the fault flips at least one tracked op. + fn has_tracked_op_flips(&self, loc_idx: usize, pauli: u8) -> bool { + self.inner.has_tracked_op_flips(loc_idx, pauli) } /// Get memory statistics for this influence map. @@ -282,7 +333,7 @@ impl PyDagFaultInfluenceMap { let dict = pyo3::types::PyDict::new(py); dict.set_item("num_locations", stats.num_locations)?; dict.set_item("total_detector_entries", stats.total_detector_entries)?; - dict.set_item("total_logical_entries", stats.total_logical_entries)?; + dict.set_item("total_dem_output_entries", stats.total_dem_output_entries)?; dict.set_item("offset_bytes", stats.offset_bytes)?; dict.set_item("data_bytes", stats.data_bytes)?; dict.set_item("total_bytes", stats.total_bytes)?; @@ -293,48 +344,57 @@ impl PyDagFaultInfluenceMap { /// /// Returns: /// Dictionary containing all CSR arrays: - /// - `num_locations`, `num_detectors`, `num_logicals` + /// - `num_locations`, `num_detectors`, `num_dem_outputs` + /// - `num_internal_dem_outputs` for the raw CSR bit-plane width /// - `detector_offsets_x`, `detector_data_x` /// - `detector_offsets_y`, `detector_data_y` /// - `detector_offsets_z`, `detector_data_z` - /// - `logical_offsets_x`, `logical_data_x` - /// - `logical_offsets_y`, `logical_data_y` - /// - `logical_offsets_z`, `logical_data_z` + /// - `dem_output_offsets_x`, `dem_output_data_x` + /// - `dem_output_offsets_y`, `dem_output_data_y` + /// - `dem_output_offsets_z`, `dem_output_data_z` fn export_csr(&self, py: Python<'_>) -> PyResult> { + let num_internal_dem_outputs = self + .inner + .influences + .max_dem_output_index() + .map_or(0, |idx| idx + 1); let ( num_locations, num_detectors, - num_logicals, + num_dem_outputs, det_off_x, det_data_x, det_off_y, det_data_y, det_off_z, det_data_z, - log_off_x, - log_data_x, - log_off_y, - log_data_y, - log_off_z, - log_data_z, + dem_output_offsets_x, + dem_output_data_x, + dem_output_offsets_y, + dem_output_data_y, + dem_output_offsets_z, + dem_output_data_z, ) = self.inner.export_csr(); let dict = pyo3::types::PyDict::new(py); dict.set_item("num_locations", num_locations)?; dict.set_item("num_detectors", num_detectors)?; - dict.set_item("num_logicals", num_logicals)?; + dict.set_item("num_dem_outputs", num_dem_outputs)?; + dict.set_item("num_internal_dem_outputs", num_internal_dem_outputs)?; + dict.set_item("num_observables", self.num_observables())?; + dict.set_item("num_tracked_ops", self.num_tracked_ops())?; dict.set_item("detector_offsets_x", det_off_x)?; dict.set_item("detector_data_x", det_data_x)?; dict.set_item("detector_offsets_y", det_off_y)?; dict.set_item("detector_data_y", det_data_y)?; dict.set_item("detector_offsets_z", det_off_z)?; dict.set_item("detector_data_z", det_data_z)?; - dict.set_item("logical_offsets_x", log_off_x)?; - dict.set_item("logical_data_x", log_data_x)?; - dict.set_item("logical_offsets_y", log_off_y)?; - dict.set_item("logical_data_y", log_data_y)?; - dict.set_item("logical_offsets_z", log_off_z)?; - dict.set_item("logical_data_z", log_data_z)?; + dict.set_item("dem_output_offsets_x", &dem_output_offsets_x)?; + dict.set_item("dem_output_data_x", &dem_output_data_x)?; + dict.set_item("dem_output_offsets_y", &dem_output_offsets_y)?; + dict.set_item("dem_output_data_y", &dem_output_data_y)?; + dict.set_item("dem_output_offsets_z", &dem_output_offsets_z)?; + dict.set_item("dem_output_data_z", &dem_output_data_z)?; Ok(dict.unbind()) } @@ -353,10 +413,10 @@ impl PyDagFaultInfluenceMap { fn __repr__(&self) -> String { format!( - "DagFaultInfluenceMap(locations={}, detectors={}, logicals={})", + "DagFaultInfluenceMap(locations={}, detectors={}, tracked_ops={})", self.num_locations(), self.num_detectors(), - self.num_logicals() + self.num_tracked_ops() ) } @@ -365,7 +425,9 @@ impl PyDagFaultInfluenceMap { } } -// --- DAG Fault Analyzer --- +// ============================================================================= +// DAG Fault Analyzer +// ============================================================================= /// Analyzes fault tolerance properties of a DAG circuit. /// @@ -453,7 +515,9 @@ impl PyDagFaultAnalyzer { } } -// --- Influence Builder --- +// ============================================================================= +// Influence Builder +// ============================================================================= /// Builder for fault influence maps with proper detector definitions. /// @@ -473,16 +537,18 @@ impl PyDagFaultAnalyzer { /// dag = DagCircuit() /// # ... build circuit ... /// -/// # Build influence map with logical operator tracking +/// # Build influence map with tracked operator probes /// builder = InfluenceBuilder(dag) -/// builder.with_logical_z([0, 1, 2]) # Top row qubits for d=3 surface code +/// builder.with_tracked_z([0, 1, 2]) # Track a Z string on these qubits /// influence_map = builder.build() /// ``` #[pyclass(name = "InfluenceBuilder", module = "pecos_rslib.qec")] pub struct PyInfluenceBuilder { dag: DagCircuit, - logical_x_qubits: Vec, - logical_z_qubits: Vec, + tracked_x_qubits: Vec, + tracked_z_qubits: Vec, + pauli_operators: Vec, + use_circuit_pauli_operators: bool, } #[pymethods] @@ -495,38 +561,86 @@ impl PyInfluenceBuilder { fn new(dag: &crate::dag_circuit_bindings::PyDagCircuit) -> Self { Self { dag: dag.inner.clone(), - logical_x_qubits: Vec::new(), - logical_z_qubits: Vec::new(), + tracked_x_qubits: Vec::new(), + tracked_z_qubits: Vec::new(), + pauli_operators: Vec::new(), + use_circuit_pauli_operators: false, } } - /// Add a logical X operator to track. + /// Add an X-string tracked operator. + /// + /// The operator is X on all specified qubits and is sensitive to Z errors. + /// + /// Args: + /// qubits: List of qubit indices for the tracked X operator. + /// + /// Returns: + /// Self for method chaining. + fn with_tracked_x(mut slf: PyRefMut<'_, Self>, qubits: Vec) -> PyRefMut<'_, Self> { + slf.tracked_x_qubits = qubits; + slf + } + + /// Add a Z-string tracked operator. /// - /// The logical X is defined as X on all specified qubits. - /// This logical is sensitive to Z errors. + /// The operator is Z on all specified qubits and is sensitive to X errors. /// /// Args: - /// qubits: List of qubit indices for the logical X operator. + /// qubits: List of qubit indices for the tracked Z operator. /// /// Returns: /// Self for method chaining. - fn with_logical_x(mut slf: PyRefMut<'_, Self>, qubits: Vec) -> PyRefMut<'_, Self> { - slf.logical_x_qubits = qubits; + fn with_tracked_z(mut slf: PyRefMut<'_, Self>, qubits: Vec) -> PyRefMut<'_, Self> { + slf.tracked_z_qubits = qubits; slf } - /// Add a logical Z operator to track. + /// Add a Pauli operator to track. /// - /// The logical Z is defined as Z on all specified qubits. - /// This logical is sensitive to X errors. + /// Each entry is a `(qubit, pauli)` tuple where pauli is "X", "Y", or "Z". /// /// Args: - /// qubits: List of qubit indices for the logical Z operator. + /// entries: List of (`qubit_index`, `pauli_str`) tuples. + /// + /// Returns: + /// Self for method chaining. + fn with_pauli_operator( + mut slf: PyRefMut<'_, Self>, + entries: Vec<(usize, String)>, + ) -> PyResult> { + let paulis: Vec<(pecos_core::Pauli, pecos_core::QubitId)> = entries + .iter() + .map(|(qubit, p)| { + let pauli = match p.to_uppercase().as_str() { + "X" => Ok(pecos_core::Pauli::X), + "Y" => Ok(pecos_core::Pauli::Y), + "Z" => Ok(pecos_core::Pauli::Z), + _ => Err(pyo3::exceptions::PyValueError::new_err(format!( + "Invalid Pauli type: {p}. Expected 'X', 'Y', or 'Z'." + ))), + }?; + Ok((pauli, pecos_core::QubitId::from(*qubit))) + }) + .collect::>()?; + slf.pauli_operators + .push(pecos_core::PauliString::with_phase_and_paulis( + pecos_core::QuarterPhase::PlusOne, + paulis, + )); + Ok(slf) + } + + /// Use annotations from the circuit (observables and Pauli operators). + /// + /// Extracts observable and `pauli_operator()` annotations from the + /// circuit. Pauli operators are tracked with positional awareness + /// (only faults before each annotation's position affect it). /// /// Returns: /// Self for method chaining. - fn with_logical_z(mut slf: PyRefMut<'_, Self>, qubits: Vec) -> PyRefMut<'_, Self> { - slf.logical_z_qubits = qubits; + fn with_circuit_annotations(mut slf: PyRefMut<'_, Self>) -> PyRefMut<'_, Self> { + slf.use_circuit_pauli_operators = true; slf } @@ -538,11 +652,23 @@ impl PyInfluenceBuilder { /// 3. Backward propagation to build the influence map /// /// Returns: - /// `DagFaultInfluenceMap` with proper detector definitions and logical tracking. + /// `DagFaultInfluenceMap` with proper detector definitions and tracked operators. fn build(&self) -> PyDagFaultInfluenceMap { - let builder = RustInfluenceBuilder::new(&self.dag) - .with_logical_x(self.logical_x_qubits.clone()) - .with_logical_z(self.logical_z_qubits.clone()); + let mut builder = RustInfluenceBuilder::new(&self.dag); + + if !self.tracked_x_qubits.is_empty() { + builder = builder.with_x(&self.tracked_x_qubits); + } + if !self.tracked_z_qubits.is_empty() { + builder = builder.with_z(&self.tracked_z_qubits); + } + + if self.use_circuit_pauli_operators { + builder = builder.with_circuit_annotations(&self.dag); + } + for pauli in &self.pauli_operators { + builder = builder.with_pauli_operator(pauli.clone()); + } let inner = builder.build(); PyDagFaultInfluenceMap { inner } @@ -550,13 +676,18 @@ impl PyInfluenceBuilder { fn __repr__(&self) -> String { format!( - "InfluenceBuilder(logical_x={:?}, logical_z={:?})", - self.logical_x_qubits, self.logical_z_qubits + "InfluenceBuilder(tracked_x={:?}, tracked_z={:?}, pauli_operators={}, circuit_annotations={})", + self.tracked_x_qubits, + self.tracked_z_qubits, + self.pauli_operators.len(), + self.use_circuit_pauli_operators, ) } } -// --- Detector Error Model --- +// ============================================================================= +// Detector Error Model +// ============================================================================= /// A Detector Error Model (DEM) in Stim-compatible format. /// @@ -583,20 +714,280 @@ pub struct PyDetectorErrorModel { inner: RustDetectorErrorModel, } +fn split_dem_outputs_for_dem( + dem_outputs: &[u32], + dem: &RustDetectorErrorModel, +) -> (Vec, Vec) { + if dem + .dem_outputs() + .iter() + .all(|output| output.kind.is_none() && output.records.is_empty() && output.pauli.is_none()) + { + return (dem_outputs.to_vec(), Vec::new()); + } + + let mut observables = Vec::new(); + let mut tracked_ops = Vec::new(); + for &output_id in dem_outputs { + if let Some(output) = dem.dem_outputs().get(output_id as usize) { + if output.is_observable() { + observables.push(output_id); + } + if output.is_tracked_operator() { + tracked_ops.push(output_id); + } + } + } + (observables, tracked_ops) +} + +fn contribution_summary_to_pydict( + py: Python<'_>, + summary: RustContributionEffectSummary, + dem: &RustDetectorErrorModel, +) -> PyResult> { + let dict = pyo3::types::PyDict::new(py); + dict.set_item("detectors", summary.effect.detectors.to_vec())?; + let dem_outputs = summary.effect.dem_outputs.to_vec(); + let (observables, tracked_ops) = split_dem_outputs_for_dem(&dem_outputs, dem); + dict.set_item("dem_outputs", &dem_outputs)?; + dict.set_item("observables", observables)?; + dict.set_item("tracked_ops", tracked_ops)?; + dict.set_item("num_contributions", summary.num_contributions)?; + dict.set_item("total_probability", summary.total_probability)?; + dict.set_item("direct_count", summary.direct_count)?; + dict.set_item("direct_probability", summary.direct_probability)?; + dict.set_item("y_decomposed_count", summary.y_decomposed_count)?; + dict.set_item("y_decomposed_probability", summary.y_decomposed_probability)?; + dict.set_item( + "graphlike_decomposable_count", + summary.graphlike_decomposable_count, + )?; + Ok(dict.unbind()) +} + +fn contribution_render_summary_to_pydict( + py: Python<'_>, + summary: RustContributionRenderSummary, + dem: &RustDetectorErrorModel, +) -> PyResult> { + let dict = pyo3::types::PyDict::new(py); + dict.set_item("detectors", summary.effect.detectors.to_vec())?; + let dem_outputs = summary.effect.dem_outputs.to_vec(); + let (observables, tracked_ops) = split_dem_outputs_for_dem(&dem_outputs, dem); + dict.set_item("dem_outputs", &dem_outputs)?; + dict.set_item("observables", observables)?; + dict.set_item("tracked_ops", tracked_ops)?; + dict.set_item("rendered_targets", summary.rendered_targets)?; + dict.set_item("num_contributions", summary.num_contributions)?; + dict.set_item("total_probability", summary.total_probability)?; + dict.set_item("combined_probability", summary.combined_probability)?; + dict.set_item("source_type_counts", summary.source_type_counts)?; + dict.set_item( + "source_type_probabilities", + summary.source_type_probabilities, + )?; + dict.set_item( + "direct_source_family_counts", + summary.direct_source_family_counts, + )?; + dict.set_item( + "direct_source_family_probabilities", + summary.direct_source_family_probabilities, + )?; + Ok(dict.unbind()) +} + +fn contribution_render_record_to_pydict( + py: Python<'_>, + record: RustContributionRenderRecord, + dem: &RustDetectorErrorModel, +) -> PyResult> { + let dict = contribution_record_to_pydict(py, record.contribution, dem)?; + let render_strategy = match record.render_strategy { + RustContributionRenderStrategy::SourceComponents => "SourceComponents", + RustContributionRenderStrategy::RecordedComponents => "RecordedComponents", + RustContributionRenderStrategy::TwoDetectorDirect => "TwoDetectorDirect", + RustContributionRenderStrategy::HyperedgeGraphlike => "HyperedgeGraphlike", + RustContributionRenderStrategy::EffectDirect => "EffectDirect", + }; + dict.bind(py) + .set_item("rendered_targets", record.rendered_targets)?; + dict.bind(py).set_item("render_strategy", render_strategy)?; + if let Some(targets) = record.recorded_component_targets { + dict.bind(py) + .set_item("recorded_component_targets", targets)?; + } + Ok(dict) +} + +fn parse_two_detector_direct_render_policy( + policy: &str, +) -> PyResult { + match policy { + "KeepDirect" => Ok(RustTwoDetectorDirectRenderPolicy::KeepDirect), + "PreferRecordedComponents" => { + Ok(RustTwoDetectorDirectRenderPolicy::PreferRecordedComponents) + } + _ => Err(pyo3::exceptions::PyValueError::new_err(format!( + "Unknown two-detector direct render policy: {policy}" + ))), + } +} + +fn contribution_record_to_pydict( + py: Python<'_>, + contribution: RustFaultContribution, + dem: &RustDetectorErrorModel, +) -> PyResult> { + fn pauli_label(pauli: Pauli) -> &'static str { + match pauli { + Pauli::I => "I", + Pauli::X => "X", + Pauli::Y => "Y", + Pauli::Z => "Z", + } + } + + let dict = pyo3::types::PyDict::new(py); + dict.set_item("detectors", contribution.effect.detectors.to_vec())?; + let dem_outputs = contribution.effect.dem_outputs.to_vec(); + let (observables, tracked_ops) = split_dem_outputs_for_dem(&dem_outputs, dem); + dict.set_item("dem_outputs", &dem_outputs)?; + dict.set_item("observables", observables)?; + dict.set_item("tracked_ops", tracked_ops)?; + dict.set_item("probability", contribution.probability)?; + dict.set_item("location_indices", contribution.location_indices.to_vec())?; + dict.set_item( + "pauli_labels", + contribution + .paulis + .iter() + .map(|pauli| pauli_label(*pauli)) + .collect::>(), + )?; + dict.set_item( + "gate_type_labels", + contribution + .source_gate_types + .iter() + .map(|gate_type| format!("{gate_type:?}")) + .collect::>(), + )?; + dict.set_item("before_flags", contribution.source_before_flags.to_vec())?; + if let Some(family) = contribution.direct_source_family { + let family_label = match family { + RustDirectSourceFamily::SingleLocation => "SingleLocation", + RustDirectSourceFamily::SingleLocationY => "SingleLocationY", + RustDirectSourceFamily::TwoLocationPlainY => "TwoLocationPlainY", + RustDirectSourceFamily::TwoLocationComponent => "TwoLocationComponent", + RustDirectSourceFamily::TwoLocationOneSidedComponent => "TwoLocationOneSidedComponent", + RustDirectSourceFamily::Other => "Other", + }; + dict.set_item("direct_source_family", family_label)?; + } + + match contribution.source_type { + RustFaultSourceType::Direct => { + dict.set_item("source_type", "Direct")?; + if let Some((first, second)) = contribution.direct_component_effects { + dict.set_item("component_1_detectors", first.detectors.to_vec())?; + dict.set_item("component_1_dem_outputs", first.dem_outputs.to_vec())?; + dict.set_item("component_2_detectors", second.detectors.to_vec())?; + dict.set_item("component_2_dem_outputs", second.dem_outputs.to_vec())?; + } + } + RustFaultSourceType::DirectOneSidedComponent => { + dict.set_item("source_type", "DirectOneSidedComponent")?; + if let Some((first, second)) = contribution.direct_component_effects { + dict.set_item("component_1_detectors", first.detectors.to_vec())?; + dict.set_item("component_1_dem_outputs", first.dem_outputs.to_vec())?; + dict.set_item("component_2_detectors", second.detectors.to_vec())?; + dict.set_item("component_2_dem_outputs", second.dem_outputs.to_vec())?; + } + } + RustFaultSourceType::YDecomposed { + x_detectors, + x_dem_outputs, + z_detectors, + z_dem_outputs, + } => { + dict.set_item("source_type", "YDecomposed")?; + dict.set_item("x_detectors", x_detectors.to_vec())?; + dict.set_item("x_dem_outputs", x_dem_outputs.to_vec())?; + dict.set_item("z_detectors", z_detectors.to_vec())?; + dict.set_item("z_dem_outputs", z_dem_outputs.to_vec())?; + } + } + + Ok(dict.unbind()) +} + #[pymethods] impl PyDetectorErrorModel { + /// Build a DetectorErrorModel directly from a circuit and noise. + /// + /// Accepts both `TickCircuit` and `DagCircuit`. Reads detector/tracked-op + /// definitions from circuit metadata. + /// + /// Example: + /// >>> dem = DetectorErrorModel.from_circuit(tc, p2=0.01) + /// >>> print(dem.to_string()) + /// >>> sampler = dem.to_sampler() + #[staticmethod] + #[pyo3(signature = (circuit, p1=0.001, p2=0.01, p_meas=0.001, p_prep=0.001))] + fn from_circuit( + circuit: &pyo3::Bound<'_, pyo3::PyAny>, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + ) -> PyResult { + use pecos_qec::fault_tolerance::dem_builder::DemBuilder; + + if let Ok(dag) = + circuit.extract::>() + { + Ok(Self { + inner: DemBuilder::from_circuit(&dag.inner, p1, p2, p_meas, p_prep), + }) + } else if let Ok(tc) = + circuit.extract::>() + { + Ok(Self { + inner: DemBuilder::from_tick_circuit(&tc.inner, p1, p2, p_meas, p_prep), + }) + } else { + Err(pyo3::exceptions::PyTypeError::new_err( + "from_circuit() expects a DagCircuit or TickCircuit", + )) + } + } + /// Number of detectors in the model. #[getter] fn num_detectors(&self) -> usize { self.inner.num_detectors() } - /// Number of logical observables in the model. + /// Number of observables in the model. #[getter] fn num_observables(&self) -> usize { self.inner.num_observables() } + /// Total number of outputs in the DEM `L` namespace. + #[getter] + fn num_dem_outputs(&self) -> usize { + self.inner.num_dem_outputs() + } + + /// Number of tracked operators in the model. + #[getter] + fn num_tracked_ops(&self) -> usize { + self.inner.num_tracked_ops() + } + /// Convert the DEM to a string in standard DEM format. /// /// Each error mechanism is output with its total probability, with no @@ -624,6 +1015,25 @@ impl PyDetectorErrorModel { self.inner.to_string_decomposed() } + /// Convert the DEM to a string with an explicit direct-2det render policy. + fn to_string_decomposed_with_two_detector_direct_policy( + &self, + policy: &str, + ) -> PyResult { + let policy = parse_two_detector_direct_render_policy(policy)?; + Ok(self + .inner + .to_string_decomposed_with_two_detector_direct_policy(policy)) + } + + /// Convert the DEM to a maximally decomposed graphlike representation. + /// + /// When possible, graphlike 2-detector mechanisms are further rewritten + /// into XORs of standalone singleton detector effects. + fn to_string_decomposed_maximally(&self) -> String { + self.inner.to_string_decomposed_maximally() + } + /// Number of tracked error contributions. #[getter] fn num_contributions(&self) -> usize { @@ -643,17 +1053,107 @@ impl PyDetectorErrorModel { /// Returns debug info about all unique contribution effects. /// - /// Shows each unique detector/logical pattern and how many contributions + /// Shows each unique detector/DEM-output pattern and how many contributions /// target it with their total probability. fn all_contribution_effects(&self) -> String { self.inner.all_contribution_effects() } + /// Build a `DemSampler` directly from this DEM — no string round-trip. + fn to_sampler(&self) -> PyResult { + use pecos_qec::fault_tolerance::dem_builder::DemSampler; + + let inner = DemSampler::from_detector_error_model(&self.inner); + Ok(PyDemSampler { inner }) + } + + /// Returns structured summaries for all unique contribution effects. + fn contribution_effect_summaries( + &self, + py: Python<'_>, + ) -> PyResult>> { + self.inner + .contribution_effect_summaries() + .into_iter() + .map(|summary| contribution_summary_to_pydict(py, summary, &self.inner)) + .collect() + } + + /// Returns structured summaries for render buckets before final regrouping. + fn contribution_render_summaries( + &self, + py: Python<'_>, + ) -> PyResult>> { + self.inner + .contribution_render_summaries() + .into_iter() + .map(|summary| contribution_render_summary_to_pydict(py, summary, &self.inner)) + .collect() + } + + /// Returns structured summaries for render buckets under an explicit + /// direct-2det render policy. + fn contribution_render_summaries_with_two_detector_direct_policy( + &self, + py: Python<'_>, + policy: &str, + ) -> PyResult>> { + let policy = parse_two_detector_direct_render_policy(policy)?; + self.inner + .contribution_render_summaries_with_two_detector_direct_policy(policy) + .into_iter() + .map(|summary| contribution_render_summary_to_pydict(py, summary, &self.inner)) + .collect() + } + + /// Returns per-contribution render records before final regrouping. + fn contribution_render_records( + &self, + py: Python<'_>, + ) -> PyResult>> { + self.inner + .contribution_render_records() + .into_iter() + .map(|record| contribution_render_record_to_pydict(py, record, &self.inner)) + .collect() + } + + /// Returns per-contribution render records under an explicit direct-2det + /// render policy. + fn contribution_render_records_with_two_detector_direct_policy( + &self, + py: Python<'_>, + policy: &str, + ) -> PyResult>> { + let policy = parse_two_detector_direct_render_policy(policy)?; + self.inner + .contribution_render_records_with_two_detector_direct_policy(policy) + .into_iter() + .map(|record| contribution_render_record_to_pydict(py, record, &self.inner)) + .collect() + } + + /// Returns source-tracked contributions for a full detector/DEM-output effect. + fn contributions_for_effect( + &self, + py: Python<'_>, + detectors: Vec, + dem_outputs: Vec, + ) -> PyResult>> { + self.inner + .contributions_for_effect(&detectors, &dem_outputs) + .into_iter() + .map(|contribution| contribution_record_to_pydict(py, contribution, &self.inner)) + .collect() + } + fn __repr__(&self) -> String { format!( - "DetectorErrorModel(detectors={}, observables={}, contributions={})", + "DetectorErrorModel(detectors={}, dem_outputs={}, observables={}, tracked_ops={}, contributions={})", self.num_detectors(), + self.num_dem_outputs(), self.num_observables(), + self.num_tracked_ops(), self.num_contributions() ) } @@ -663,14 +1163,21 @@ impl PyDetectorErrorModel { } } -// --- DEM Builder --- +// ============================================================================= +// DEM Builder +// ============================================================================= -/// Builder for Detector Error Models (DEMs). +/// Advanced builder for Detector Error Models (DEMs). /// -/// Constructs a DEM from a fault influence map and detector/observable metadata. -/// Uses the per-qubit fault model for accurate depolarizing noise analysis. +/// For most use cases, prefer `DetectorErrorModel.from_circuit()` or +/// `DemSampler.from_circuit()` which handle everything automatically. /// -/// # Example +/// Use `DemBuilder` directly when you need: +/// - A custom fault influence map +/// - Non-standard noise configuration +/// - Manual detector and observable definitions +/// +/// # Example (advanced) /// /// ```python /// from pecos_rslib.qec import DagFaultAnalyzer, DemBuilder @@ -682,7 +1189,13 @@ impl PyDetectorErrorModel { /// # Build DEM /// builder = DemBuilder(influence_map) /// builder.with_noise(0.01, 0.01, 0.01, 0.01) -/// builder.with_detectors_json('[{"id": 0, "coords": [0, 0, 0], "records": [-1]}]') +/// builder.with_detectors_json( +/// '[{"id": 0, "coords": [0, 0, 0], "records": [-1]}, ' +/// '{"detector_id": 1, "coords": [1, 0, 0], "records": [-2]}]' +/// ) +/// builder.with_observables_json( +/// '[{"id": 0, "records": [-1]}, {"observable_id": 1, "records": [-2]}]' +/// ) /// dem = builder.build() /// /// print(dem.to_string()) @@ -690,15 +1203,10 @@ impl PyDetectorErrorModel { #[pyclass(name = "DemBuilder", module = "pecos_rslib.qec")] pub struct PyDemBuilder { influence_map: RustDagFaultInfluenceMap, - p1: f64, - p2: f64, - p_meas: f64, - p_init: f64, + noise: NoiseConfig, detectors_json: Option, observables_json: Option, num_measurements: Option, - /// Measurement order: list of qubits in `TickCircuit` measurement execution order. - /// This allows proper mapping between record offsets and influence map indices. measurement_order: Option>, } @@ -712,10 +1220,7 @@ impl PyDemBuilder { fn new(influence_map: &PyDagFaultInfluenceMap) -> Self { Self { influence_map: influence_map.inner.clone(), - p1: 0.01, - p2: 0.01, - p_meas: 0.01, - p_init: 0.01, + noise: NoiseConfig::default(), detectors_json: None, observables_json: None, num_measurements: None, @@ -729,21 +1234,35 @@ impl PyDemBuilder { /// p1: Single-qubit depolarizing error rate. /// p2: Two-qubit depolarizing error rate. /// `p_meas`: Measurement error rate. - /// `p_init`: Initialization (prep) error rate. + /// `p_prep`: Initialization (prep) error rate. + /// `p_idle`: Optional idle noise rate per time unit. + /// t1: Optional T1 relaxation time. + /// t2: Optional T2 dephasing time. /// /// Returns: /// Self for method chaining. + #[pyo3(signature = (p1, p2, p_meas, p_prep, p_idle=None, t1=None, t2=None, idle_rz=None))] + #[allow(clippy::too_many_arguments)] fn with_noise( mut slf: PyRefMut<'_, Self>, p1: f64, p2: f64, p_meas: f64, - p_init: f64, + p_prep: f64, + p_idle: Option, + t1: Option, + t2: Option, + idle_rz: Option, ) -> PyRefMut<'_, Self> { - slf.p1 = p1; - slf.p2 = p2; - slf.p_meas = p_meas; - slf.p_init = p_init; + let mut noise = NoiseConfig::new(p1, p2, p_meas, p_prep); + noise.p_idle = p_idle.unwrap_or(0.0); + if let (Some(t1_val), Some(t2_val)) = (t1, t2) { + noise = noise.set_t1_t2(t1_val, t2_val); + } + if let Some(rz) = idle_rz { + noise = noise.set_idle_rz(rz); + } + slf.noise = noise; slf } @@ -752,6 +1271,7 @@ impl PyDemBuilder { /// Args: /// json: JSON string with detector definitions. /// Format: [{"id": 0, "coords": [x, y, t], "records": [-1, -5]}, ...] + /// Public surface descriptors using "`detector_id`" are also accepted. /// /// Returns: /// Self for method chaining. @@ -762,12 +1282,8 @@ impl PyDemBuilder { /// Set the observable definitions from JSON. /// - /// Args: - /// json: JSON string with observable definitions. - /// Format: [{"id": 0, "records": [-1, -3, -5]}, ...] - /// - /// Returns: - /// Self for method chaining. + /// Tracked operators are carried by the influence map; this helper is for + /// observable metadata. fn with_observables_json(mut slf: PyRefMut<'_, Self>, json: String) -> PyRefMut<'_, Self> { slf.observables_json = Some(json); slf @@ -814,12 +1330,8 @@ impl PyDemBuilder { /// Raises: /// `ValueError`: If the detector or observable JSON is malformed. fn build(&self) -> PyResult { - let mut builder = RustDemBuilder::new(&self.influence_map).with_noise( - self.p1, - self.p2, - self.p_meas, - self.p_init, - ); + let mut builder = + RustDemBuilder::new(&self.influence_map).with_noise_config(self.noise.clone()); if let Some(num) = self.num_measurements { builder = builder.with_num_measurements(num); @@ -852,606 +1364,2071 @@ impl PyDemBuilder { fn __repr__(&self) -> String { format!( - "DemBuilder(p1={}, p2={}, p_meas={}, p_init={})", - self.p1, self.p2, self.p_meas, self.p_init + "DemBuilder(p1={}, p2={}, p_meas={}, p_prep={}, p_idle={:?})", + self.noise.p1, self.noise.p2, self.noise.p_meas, self.noise.p_prep, self.noise.p_idle ) } } -// --- Helper Functions --- +// ============================================================================= +// Helper Functions +// ============================================================================= -/// Parse detector records from JSON string. +/// `UnionFind` decoder that passes LLRs (from DEM error priors) for weighted decoding. /// -/// Extracts the "records" arrays from detector definitions. -fn parse_detector_records(detectors_json: &str) -> PyResult>> { - if detectors_json.is_empty() { - return Ok(Vec::new()); - } - - let detectors: Vec = serde_json::from_str(detectors_json) - .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("Invalid JSON: {e}")))?; - - let mut detector_records = Vec::with_capacity(detectors.len()); +/// The generic `CheckMatrixObservableDecoder` calls `Decoder::decode` which +/// passes empty LLRs. This wrapper stores the LLRs and passes them through +/// to the C++ UF decoder each shot, giving it edge-weight information. +struct WeightedUfObservableDecoder { + decoder: pecos_decoders::UnionFindDecoder, + dcm: pecos_decoder_core::dem::DemCheckMatrix, + llrs: Vec, +} - for det in &detectors { - let records = det - .get("records") - .and_then(|r| r.as_array()) - .ok_or_else(|| { - pyo3::exceptions::PyValueError::new_err("Detector missing 'records' array") - })?; +impl pecos_decoders::ObservableDecoder for WeightedUfObservableDecoder { + fn decode_to_observables( + &mut self, + syndrome: &[u8], + ) -> Result { + let arr = ndarray::Array1::from_vec(syndrome.to_vec()); + // bits_per_step=1: grow one bit at a time, sorted by LLR weight. + // bits_per_step=0 with non-empty LLRs causes the C++ UF decoder to + // add zero bits per step, looping forever. + let result = self + .decoder + .decode(&arr.view(), &self.llrs, 1) + .map_err(|e| pecos_decoder_core::DecoderError::DecodingFailed(e.to_string()))?; + Ok(self + .dcm + .observables_mask_from_correction(result.decoding.as_slice().unwrap_or(&[]))) + } +} - let offsets: Vec = records - .iter() - .map(|r| { - #[allow(clippy::cast_possible_truncation)] // measurement record offsets fit in i32 - r.as_i64().map(|v| v as i32).ok_or_else(|| { - pyo3::exceptions::PyValueError::new_err("Record offset must be integer") - }) - }) - .collect::>>()?; +/// Wrapper that relabels syndromes before passing to an inner decoder. +/// +/// Used for Fusion Blossom parallel where detector IDs need to be +/// round-contiguous for partitioning. +struct RelabeledObservableDecoder { + decoder: pecos_decoders::FusionBlossomDecoder, + old_to_new: Vec, +} - detector_records.push(offsets); +impl pecos_decoders::ObservableDecoder for RelabeledObservableDecoder { + fn decode_to_observables( + &mut self, + syndrome: &[u8], + ) -> Result { + // Relabel syndrome into the expanded vertex space (detectors + virtual + gap) + let expected = self.decoder.num_nodes(); + let mut relabeled = vec![0u8; expected]; + for (old_id, &val) in syndrome.iter().enumerate() { + if old_id < self.old_to_new.len() { + let new_id = self.old_to_new[old_id]; + if new_id < expected { + relabeled[new_id] = val; + } + } + } + let arr = ndarray::Array1::from_vec(relabeled); + let result = self + .decoder + .decode(&arr.view()) + .map_err(|e| pecos_decoder_core::DecoderError::DecodingFailed(e.to_string()))?; + let mut mask = 0u64; + for (i, &v) in result.observable.iter().enumerate() { + if v != 0 { + mask |= 1 << i; + } + } + Ok(mask) } - - Ok(detector_records) } -/// Parse observable records from JSON string. -/// -/// Extracts the "records" arrays from observable definitions. -fn parse_observable_records(observables_json: &str) -> PyResult>> { - if observables_json.is_empty() { - return Ok(Vec::new()); +/// Convert a `DemMatchingGraph` to a DEM string for inner decoder construction. +fn subgraph_to_dem_string(graph: &pecos_decoder_core::DemMatchingGraph) -> String { + let mut lines = Vec::new(); + for edge in &graph.edges { + let p = edge.probability; + let mut targets = Vec::new(); + targets.push(format!("D{}", edge.node1)); + if let Some(n2) = edge.node2 { + targets.push(format!("D{n2}")); + } + for &obs in &edge.observables { + targets.push(format!("L{obs}")); + } + lines.push(format!("error({p}) {}", targets.join(" "))); } + lines.join("\n") +} - let observables: Vec = serde_json::from_str(observables_json) - .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("Invalid JSON: {e}")))?; +/// Create an `ObservableDecoder` from a DEM string and decoder type name. +/// +/// This is the shared factory used by `SampleBatch.decode_count`, +/// `DemSampler.sample_decode_count`, and the parallel variants. +fn create_observable_decoder( + dem: &str, + decoder_type: &str, +) -> PyResult> { + use pecos_decoder_core::{CheckMatrixObservableDecoder, DemCheckMatrix}; + use pecos_decoders::{ + BeliefFindDecoder, BpLsdDecoder, BpMethod, BpOsdDecoder, BpSchedule, InputVectorType, + MinSumBpBuilder, OsdMethod, PyMatchingDecoder, RelayBpBuilder, SparseMatrix, + TesseractConfig, TesseractDecoder, UfMethod, UnionFindDecoder, + }; - let mut observable_records = Vec::with_capacity(observables.len()); + match decoder_type { + "pymatching" => { + // Default: correlated matching enabled (exploits X-Z correlations + // from depolarizing noise for ~20% fewer errors at d>=5). + let d = PyMatchingDecoder::from_dem_with_correlations(dem, true) + .map_err(|e| PyErr::new::(e.to_string()))?; + Ok(Box::new(d)) + } + "pymatching_uncorrelated" => { + let d = PyMatchingDecoder::from_dem(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + Ok(Box::new(d)) + } + "tesseract" => { + let d = TesseractDecoder::new(dem, TesseractConfig::fast()) + .map_err(|e| PyErr::new::(e.to_string()))?; + Ok(Box::new(d)) + } + s if s.starts_with("k_mwpm") => { + // K-MWPM: enumerate K matchings via decoding tree, majority vote. + // Uses UF as the inner MWPM solver (supports decode_with_weights). + use pecos_decoder_core::k_mwpm::{KMwpmConfig, KMwpmDecoder}; + let mut k: usize = 10; + if let Some(params) = s.strip_prefix("k_mwpm:") { + for kv in params.split(',') { + let parts: Vec<&str> = kv.splitn(2, '=').collect(); + if parts.len() == 2 && (parts[0] == "K" || parts[0] == "k") { + k = parts[1].parse().unwrap_or(10); + } + } + } + // Use FB (standard, non-correlated) as the inner MWPM. + // K-MWPM captures correlation benefit by exploring multiple matchings. + let fb = pecos_decoders::FusionBlossomDecoder::from_dem(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + Ok(Box::new(KMwpmDecoder::new(fb, KMwpmConfig { k }))) + } + "astar" => { + let d = + pecos_decoders::AStarDecoder::from_dem(dem, pecos_decoders::AStarConfig::default()) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + Ok(Box::new(d)) + } + "astar_full" => { + // A* on non-decomposed DEM (preserves hyperedges for Y-error correlations). + let d = pecos_decoders::AStarDecoder::from_dem_full( + dem, + pecos_decoders::AStarConfig::default(), + ) + .map_err(|e| PyErr::new::(e.to_string()))?; + Ok(Box::new(d)) + } + "fusion_blossom" => { + // Auto: use parallel for large problems (500+ detectors), serial otherwise + let graph = pecos_decoder_core::DemMatchingGraph::from_dem_str(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + let has_coords = graph + .detector_coords + .iter() + .any(std::option::Option::is_some); + if graph.num_detectors >= 500 && has_coords { + return create_observable_decoder(dem, "fusion_blossom_parallel"); + } + create_observable_decoder(dem, "fusion_blossom_serial") + } + "fusion_blossom_serial" => { + use pecos_decoder_core::DemMatchingGraph; + use pecos_decoders::{FusionBlossomConfig, FusionBlossomDecoder}; + let graph = DemMatchingGraph::from_dem_str(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + + // Use absolute weight scaling. Fusion Blossom uses integer weights; + // we multiply by 1000 for precision (matching the internal 1000x + // scaling in add_edge). The upstream tutorial uses relative scaling + // but that loses weight ordering when the range is narrow. + + let config = FusionBlossomConfig { + num_nodes: Some(graph.num_detectors), + num_observables: graph.num_observables, + ..Default::default() + }; + let mut decoder = FusionBlossomDecoder::new(config) + .map_err(|e| PyErr::new::(e.to_string()))?; + for edge in &graph.edges { + let obs: Vec = edge.observables.iter().map(|&o| o as usize).collect(); + let scaled_weight = edge.weight; + match edge.node2 { + Some(n2) => { + decoder + .add_edge(edge.node1 as usize, n2 as usize, &obs, Some(scaled_weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + } + None => { + decoder + .add_boundary_edge(edge.node1 as usize, &obs, Some(scaled_weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + } + } + } + Ok(Box::new(decoder)) + } + "fusion_blossom_correlated" => { + use pecos_decoder_core::DemMatchingGraph; + use pecos_decoder_core::correlation_table::CorrelationTable; + use pecos_decoder_core::two_pass_decoder::TwoPassDecoder; + use pecos_decoders::{FusionBlossomConfig, FusionBlossomDecoder}; + + let graph = DemMatchingGraph::from_dem_str(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + + let config = FusionBlossomConfig { + num_nodes: Some(graph.num_detectors), + num_observables: graph.num_observables, + ..Default::default() + }; + let mut decoder = FusionBlossomDecoder::new(config) + .map_err(|e| PyErr::new::(e.to_string()))?; + + // Build edge index map and weights + let mut edge_index_map = std::collections::BTreeMap::new(); + let mut base_weights = Vec::new(); + for (idx, edge) in graph.edges.iter().enumerate() { + let obs: Vec = edge.observables.iter().map(|&o| o as usize).collect(); + base_weights.push(edge.weight); + let key = if let Some(n2) = edge.node2 { + decoder + .add_edge(edge.node1 as usize, n2 as usize, &obs, Some(edge.weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + if edge.node1 <= n2 { + (edge.node1, n2) + } else { + (n2, edge.node1) + } + } else { + decoder + .add_boundary_edge(edge.node1 as usize, &obs, Some(edge.weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + (edge.node1, u32::MAX) + }; + edge_index_map.insert(key, idx); + } - for obs in &observables { - let records = obs - .get("records") - .and_then(|r| r.as_array()) - .ok_or_else(|| { - pyo3::exceptions::PyValueError::new_err("Observable missing 'records' array") - })?; + // Build correlation table from DEM decomposition + let corr_table = + CorrelationTable::from_dem_str(dem, &edge_index_map, graph.edges.len()).map_err( + |e| PyErr::new::(e.to_string()), + )?; - let offsets: Vec = records - .iter() - .map(|r| { - #[allow(clippy::cast_possible_truncation)] // measurement record offsets fit in i32 - r.as_i64().map(|v| v as i32).ok_or_else(|| { - pyo3::exceptions::PyValueError::new_err("Record offset must be integer") - }) - }) - .collect::>>()?; + let two_pass = TwoPassDecoder::new(decoder, base_weights, corr_table); + Ok(Box::new(two_pass)) + } + s if s.starts_with("perturbed_fb_corr") => { + // Fast perturbed correlated FB ensemble. + // Parses DemCheckMatrix once, builds K members with perturbed weights + // via from_check_matrix_correlated (skips DEM text re-parsing). + + use pecos_decoder_core::ensemble::EnsembleDecoder; + use pecos_decoders::FusionBlossomDecoder; + + let mut k: usize = 5; + let mut sigma: f64 = 0.5; + let mut seed: u64 = 42; + if let Some(params) = s.strip_prefix("perturbed_fb_corr:") { + for kv in params.split(',') { + let parts: Vec<&str> = kv.splitn(2, '=').collect(); + if parts.len() == 2 { + match parts[0] { + "K" | "k" => k = parts[1].parse().unwrap_or(5), + "sigma" | "s" => sigma = parts[1].parse().unwrap_or(0.5), + "seed" => seed = parts[1].parse().unwrap_or(42), + _ => {} + } + } + } + } - observable_records.push(offsets); - } + // Build K members using from_dem_correlated on perturbed DEM text. + // This is faster than the generic perturbed: path because it reuses + // the same DEM parsing approach that FB_corr uses (which handles + // duplicate edges correctly). + let mut members: Vec> = + Vec::with_capacity(k); + + // Unperturbed anchor. + members.push(Box::new( + FusionBlossomDecoder::from_dem_correlated(dem).map_err(|e| { + PyErr::new::(e.to_string()) + })?, + )); - Ok(observable_records) -} + // K-1 perturbed members. + let mut rng = pecos_random::PecosRng::seed_from_u64(seed); + let mut next_f64 = || rng.next_f64(); + for _ in 1..k { + let perturbed = + pecos_decoder_core::perturbed::perturb_dem(dem, sigma, &mut next_f64); + if let Ok(dec) = FusionBlossomDecoder::from_dem_correlated(&perturbed) { + members.push(Box::new(dec)); + } + } -// --- Measurement Noise Model --- + Ok(Box::new(EnsembleDecoder::new(members))) + } + "fusion_blossom_parallel" => { + use pecos_decoder_core::DemMatchingGraph; + use pecos_decoders::{FusionBlossomConfig, FusionBlossomDecoder, PartitionConfig}; + + let graph = DemMatchingGraph::from_dem_str(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + + // Group detectors by time coordinate for round-contiguous relabeling. + let mut round_groups: std::collections::BTreeMap> = + std::collections::BTreeMap::new(); + #[allow(clippy::cast_possible_truncation)] // time coords and detector IDs are small + for (id, coord) in graph.detector_coords.iter().enumerate() { + let t = coord + .as_ref() + .and_then(|c| c.get(2)) + .copied() + .unwrap_or(0.0); + round_groups + .entry((t * 1000.0) as i64) + .or_default() + .push(id as u32); + } + let num_rounds = round_groups.len(); + if num_rounds < 2 { + // Not enough rounds to partition -- fall back to serial + return create_observable_decoder(dem, "fusion_blossom"); + } -/// A Measurement Noise Model (MNM) for fast approximate sampling. -/// -/// Unlike a DEM which maps error mechanisms to detector effects, the MNM maps -/// directly to measurement effects. This allows sampling raw measurement outcomes -/// without needing detector definitions. -/// -/// # Sampling Modes -/// -/// - **Per-fault-location** (accurate): Sample each (location, Pauli) independently -/// - **Per-mechanism** (fast, approximate): Sample each unique measurement effect once -/// -/// The MNM enables the fast per-mechanism mode while still producing raw measurement -/// outcomes that can be converted to detection events using any detector definition. -/// -/// # Example -/// -/// ```python -/// from pecos_rslib.qec import MemBuilder -/// -/// # Build MNM from influence map -/// mnm = MemBuilder(influence_map).with_noise(0.01, 0.01, 0.01, 0.01).build() -/// -/// # Sample measurement outcomes -/// outcomes = mnm.sample() -/// ``` -#[pyclass(name = "MeasurementNoiseModel", module = "pecos_rslib.qec")] -pub struct PyMeasurementNoiseModel { - inner: RustMeasurementNoiseModel, -} + // Relabel: each round gets [detectors] [boundary_virtual] contiguously. + // This ensures boundary edges stay within the same vertex range as + // the round's detectors. + let num_dets = graph.num_detectors; + let mut old_to_new = vec![0usize; num_dets]; + let mut det_to_round = vec![0usize; num_dets]; + let mut new_id = 0usize; + let mut round_starts = Vec::new(); + let mut round_ends = Vec::new(); // end of each round (after boundary vertex) + let mut partition_boundary = Vec::new(); + for (round_idx, (_round, ids)) in round_groups.iter().enumerate() { + round_starts.push(new_id); + for &old_id in ids { + old_to_new[old_id as usize] = new_id; + det_to_round[old_id as usize] = round_idx; + new_id += 1; + } + // Virtual boundary vertex for this round, right after detectors + partition_boundary.push(new_id); + new_id += 1; + round_ends.push(new_id); + } + let total_vertex_num = new_id; + + let config = FusionBlossomConfig { + num_nodes: Some(total_vertex_num), + num_observables: graph.num_observables, + ..Default::default() + }; + let mut decoder = FusionBlossomDecoder::new(config) + .map_err(|e| PyErr::new::(e.to_string()))?; + // Mark per-partition boundary vertices as virtual + for &bnd in &partition_boundary { + decoder.virtual_vertices.push(bnd); + } -#[pymethods] -impl PyMeasurementNoiseModel { - /// Number of distinct mechanisms in the model. - #[getter] - fn num_mechanisms(&self) -> usize { - self.inner.num_mechanisms() - } + for edge in &graph.edges { + let obs: Vec = edge.observables.iter().map(|&o| o as usize).collect(); + let n1 = old_to_new[edge.node1 as usize]; + if let Some(n2) = edge.node2 { + let n2 = old_to_new[n2 as usize]; + decoder + .add_edge(n1, n2, &obs, Some(edge.weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + } else { + // Route boundary edge to this detector's round boundary vertex + let round_idx = det_to_round[edge.node1 as usize]; + let bnd = partition_boundary[round_idx]; + decoder + .add_edge(n1, bnd, &obs, Some(edge.weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + } + } - /// Number of measurements in the circuit. - #[getter] - fn num_measurements(&self) -> usize { - self.inner.num_measurements - } + // Build partition config matching the upstream time-partition pattern. + // Each partition covers multiple rounds. The interface between + // adjacent partitions is the first round of the later partition's + // rounds (which is skipped from its range, creating the gap). + + // Partition ranges: each partition covers multiple rounds of detectors + // plus that partition's boundary vertices. + // Boundary vertices are at indices [num_dets, num_dets + num_rounds). + // We assign boundary vertex for round R to the partition that contains round R. + let partition_num = num_rounds.clamp(2, 4); + + // Build partition config. Each partition covers multiple rounds. + // Partition boundaries fall between rounds. The first round of + // each non-first partition is the interface gap (its vertices + // are excluded from the partition range). + let mut part_config = PartitionConfig::new(total_vertex_num); + part_config.partitions.clear(); + + for p_idx in 0..partition_num { + let start_round = p_idx * num_rounds / partition_num; + let end_round = (p_idx + 1) * num_rounds / partition_num; + // First partition starts at its first round. + // Subsequent partitions skip their first round (interface gap). + let start_vertex = if p_idx == 0 { + round_starts[start_round] + } else { + round_starts[(start_round + 1).min(num_rounds - 1)] + }; + let end_vertex = round_ends[end_round - 1]; + if start_vertex < end_vertex { + part_config + .partitions + .push(pecos_decoders::VertexRange::new(start_vertex, end_vertex)); + } + } - /// Sample measurement outcomes. - /// - /// Each noise mechanism is sampled once according to its probability. - /// When a mechanism fires, its measurements are XOR'd into the outcomes. - /// - /// Args: - /// seed: Optional random seed for reproducibility. - /// - /// Returns: - /// List of boolean measurement outcomes. - #[pyo3(signature = (seed=None))] - fn sample(&self, seed: Option) -> Vec { - use pecos_random::PecosRng; - use rand::RngExt; + // Linear fusion chain: merge adjacent partitions left to right + let n_parts = part_config.partitions.len(); + part_config.fusions.clear(); + if n_parts > 1 { + let mut active: Vec = (0..n_parts).collect(); + while active.len() > 1 { + let mut next_active = Vec::new(); + let mut i = 0; + while i + 1 < active.len() { + part_config.fusions.push((active[i], active[i + 1])); + next_active.push(n_parts + part_config.fusions.len() - 1); + i += 2; + } + if i < active.len() { + next_active.push(active[i]); + } + active = next_active; + } + } - let mut rng = match seed { - Some(s) => PecosRng::seed_from_u64(s), - None => PecosRng::seed_from_u64(rand::rng().random()), - }; + decoder.set_partition_config(part_config); - self.inner.sample(&mut rng) + Ok(Box::new(RelabeledObservableDecoder { + decoder, + old_to_new, + })) + } + "bp_osd" | "bp_lsd" | "belief_find" | "union_find" | "relay_bp" | "min_sum_bp" => { + let dcm = DemCheckMatrix::from_dem_str(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + let sparse_h = SparseMatrix::from_dense(&dcm.check_matrix.view()); + match decoder_type { + "bp_osd" => { + let d = BpOsdDecoder::new( + &sparse_h, + None, + Some(&dcm.error_priors), + 100, + BpMethod::ProductSum, + BpSchedule::Parallel, + 1.0, + OsdMethod::Osd0, + 0, + InputVectorType::Syndrome, + None, + None, + None, + ) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + Ok(Box::new(CheckMatrixObservableDecoder::new(d, dcm))) + } + "bp_lsd" => { + let d = BpLsdDecoder::new( + &sparse_h, + None, + Some(&dcm.error_priors), + 100, + BpMethod::ProductSum, + BpSchedule::Parallel, + 1.0, + OsdMethod::Off, + 0, + 0, + InputVectorType::Syndrome, + None, + None, + None, + ) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + Ok(Box::new(CheckMatrixObservableDecoder::new(d, dcm))) + } + "belief_find" => { + let d = BeliefFindDecoder::new( + &sparse_h, + None, + Some(&dcm.error_priors), + 100, + BpMethod::ProductSum, + 1.0, + BpSchedule::Parallel, + None, + None, + None, + UfMethod::Inversion, + 0, + ) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + Ok(Box::new(CheckMatrixObservableDecoder::new(d, dcm))) + } + "union_find" => { + let d = UnionFindDecoder::new(&sparse_h, UfMethod::Inversion).map_err(|e| { + PyErr::new::(e.to_string()) + })?; + let llrs: Vec = dcm + .error_priors + .iter() + .map(|&p| { + if p > 0.0 && p < 1.0 { + ((1.0 - p) / p).ln() + } else { + 0.0 + } + }) + .collect(); + Ok(Box::new(WeightedUfObservableDecoder { + decoder: d, + dcm, + llrs, + })) + } + "relay_bp" => { + let h_view = dcm.check_matrix.view(); + let d = RelayBpBuilder::new(&h_view) + .error_priors(&dcm.error_priors) + .build() + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + Ok(Box::new(CheckMatrixObservableDecoder::new(d, dcm))) + } + "min_sum_bp" => { + let h_view = dcm.check_matrix.view(); + let d = MinSumBpBuilder::new(&h_view) + .error_priors(&dcm.error_priors) + .build() + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + Ok(Box::new(CheckMatrixObservableDecoder::new(d, dcm))) + } + _ => unreachable!(), + } + } + // UF decoder: "pecos_uf" (fast), "pecos_uf:balanced", "pecos_uf:accurate" + // Also accepts legacy "pecos_uf_correlated" as alias for balanced. + "pecos_uf" | "pecos_uf:fast" => { + let d = + pecos_decoders::UfDecoder::from_dem(dem, pecos_decoders::UfDecoderConfig::fast()) + .map_err(|e| PyErr::new::(e.to_string()))?; + Ok(Box::new(d)) + } + "pecos_uf:balanced" | "pecos_uf_correlated" => { + // Two-pass correlated UF: first pass identifies matched edges, + // correlation table adjusts weights, second pass re-decodes. + use pecos_decoder_core::DemMatchingGraph; + use pecos_decoder_core::correlation_table::CorrelationTable; + use pecos_decoder_core::two_pass_decoder::TwoPassDecoder; + + let graph = DemMatchingGraph::from_dem_str(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + + let mut edge_index_map = std::collections::BTreeMap::new(); + let mut base_weights = Vec::with_capacity(graph.edges.len()); + for (idx, edge) in graph.edges.iter().enumerate() { + base_weights.push(edge.weight); + let key = match edge.node2 { + Some(n2) => { + if edge.node1 <= n2 { + (edge.node1, n2) + } else { + (n2, edge.node1) + } + } + None => (edge.node1, u32::MAX), + }; + edge_index_map.insert(key, idx); + } + + let corr_table = + CorrelationTable::from_dem_str(dem, &edge_index_map, graph.edges.len()).map_err( + |e| PyErr::new::(e.to_string()), + )?; + + let uf = pecos_decoders::UfDecoder::from_matching_graph( + &graph, + pecos_decoders::UfDecoderConfig::balanced(), + ); + let two_pass = TwoPassDecoder::new(uf, base_weights, corr_table); + Ok(Box::new(two_pass)) + } + "pecos_uf:bp" => { + // BP+UF hybrid: flooding BP (fast, good for d<=7). + let d = + pecos_decoders::BpUfDecoder::from_dem(dem, pecos_decoders::BpUfConfig::balanced()) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + Ok(Box::new(d)) + } + "belief_matching_mgbp" => { + // Belief-matching with matching-graph BP (Hack et al. 2026 style). + // BP runs on the matching graph (simpler, better convergence) + // instead of the Tanner graph. + use pecos_decoder_core::DemMatchingGraph; + use pecos_decoder_core::bp_matching::BpMatchingDecoder; + use pecos_decoder_core::correlation_table::CorrelationTable; + use pecos_decoders::{FusionBlossomConfig, FusionBlossomDecoder}; + + let bp = pecos_decoders::BpUfDecoder::from_dem( + dem, + pecos_decoders::BpUfConfig::matching_bp(), + ) + .map_err(|e| PyErr::new::(e.to_string()))?; + + let graph = DemMatchingGraph::from_dem_str(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + let config = FusionBlossomConfig { + num_nodes: Some(graph.num_detectors), + num_observables: graph.num_observables, + ..Default::default() + }; + let mut fb = FusionBlossomDecoder::new(config) + .map_err(|e| PyErr::new::(e.to_string()))?; + let mut edge_index_map = std::collections::BTreeMap::new(); + for (idx, edge) in graph.edges.iter().enumerate() { + let obs: Vec = edge.observables.iter().map(|&o| o as usize).collect(); + let key = if let Some(n2) = edge.node2 { + fb.add_edge(edge.node1 as usize, n2 as usize, &obs, Some(edge.weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + if edge.node1 <= n2 { + (edge.node1, n2) + } else { + (n2, edge.node1) + } + } else { + fb.add_boundary_edge(edge.node1 as usize, &obs, Some(edge.weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + (edge.node1, u32::MAX) + }; + edge_index_map.insert(key, idx); + } + let corr_table = + CorrelationTable::from_dem_str(dem, &edge_index_map, graph.edges.len()).map_err( + |e| PyErr::new::(e.to_string()), + )?; + Ok(Box::new(BpMatchingDecoder::with_correlations( + fb, bp, corr_table, + ))) + } + "pecos_uf:bp_serial" => { + // BP+UF hybrid: serial BP (slower, maintains threshold at d=7-11+). + let d = + pecos_decoders::BpUfDecoder::from_dem(dem, pecos_decoders::BpUfConfig::accurate()) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + Ok(Box::new(d)) + } + "belief_matching" => { + // Belief-matching: BP soft info → Fusion Blossom MWPM with dynamic weights. + // Achieves ~0.94% circuit-level threshold (Higgott 2022). + use pecos_decoder_core::DemMatchingGraph; + use pecos_decoder_core::bp_matching::BpMatchingDecoder; + use pecos_decoders::{FusionBlossomConfig, FusionBlossomDecoder}; + + // Build BP weight provider. + let bp = + pecos_decoders::BpUfDecoder::from_dem(dem, pecos_decoders::BpUfConfig::balanced()) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + + // Build Fusion Blossom as the matching backend. + let graph = DemMatchingGraph::from_dem_str(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + let config = FusionBlossomConfig { + num_nodes: Some(graph.num_detectors), + num_observables: graph.num_observables, + ..Default::default() + }; + let mut fb = FusionBlossomDecoder::new(config) + .map_err(|e| PyErr::new::(e.to_string()))?; + for edge in &graph.edges { + let obs: Vec = edge.observables.iter().map(|&o| o as usize).collect(); + match edge.node2 { + Some(n2) => { + fb.add_edge(edge.node1 as usize, n2 as usize, &obs, Some(edge.weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + } + None => { + fb.add_boundary_edge(edge.node1 as usize, &obs, Some(edge.weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + } + } + } + + Ok(Box::new(BpMatchingDecoder::new(fb, bp))) + } + "belief_matching_correlated" => { + // Correlated belief-matching: BP + correlation table + Fusion Blossom MWPM. + // Two-pass: BP weights → MWPM → correlation adjustment → MWPM. + // Combines BP soft info with X-Z cross-lattice correlations. + use pecos_decoder_core::DemMatchingGraph; + use pecos_decoder_core::bp_matching::BpMatchingDecoder; + use pecos_decoder_core::correlation_table::CorrelationTable; + use pecos_decoders::{FusionBlossomConfig, FusionBlossomDecoder}; + + let bp = + pecos_decoders::BpUfDecoder::from_dem(dem, pecos_decoders::BpUfConfig::balanced()) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + + let graph = DemMatchingGraph::from_dem_str(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + + // Build Fusion Blossom. + let config = FusionBlossomConfig { + num_nodes: Some(graph.num_detectors), + num_observables: graph.num_observables, + ..Default::default() + }; + let mut fb = FusionBlossomDecoder::new(config) + .map_err(|e| PyErr::new::(e.to_string()))?; + + let mut edge_index_map = std::collections::BTreeMap::new(); + for (idx, edge) in graph.edges.iter().enumerate() { + let obs: Vec = edge.observables.iter().map(|&o| o as usize).collect(); + let key = if let Some(n2) = edge.node2 { + fb.add_edge(edge.node1 as usize, n2 as usize, &obs, Some(edge.weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + if edge.node1 <= n2 { + (edge.node1, n2) + } else { + (n2, edge.node1) + } + } else { + fb.add_boundary_edge(edge.node1 as usize, &obs, Some(edge.weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + (edge.node1, u32::MAX) + }; + edge_index_map.insert(key, idx); + } + + // Build correlation table from decomposed DEM. + let corr_table = + CorrelationTable::from_dem_str(dem, &edge_index_map, graph.edges.len()).map_err( + |e| PyErr::new::(e.to_string()), + )?; + + Ok(Box::new(BpMatchingDecoder::with_correlations( + fb, bp, corr_table, + ))) + } + s if s.starts_with("belief_matching_hybrid:") => { + // Hybrid correlated belief-matching: non-decomposed DEM for BP, + // decomposed DEM for matching graph + correlations. + // Format: "belief_matching_hybrid:" + // The main `dem` param is the decomposed DEM. + use pecos_decoder_core::DemMatchingGraph; + use pecos_decoder_core::bp_matching::BpMatchingDecoder; + use pecos_decoder_core::correlation_table::CorrelationTable; + use pecos_decoders::{FusionBlossomConfig, FusionBlossomDecoder}; + + let full_dem = &s["belief_matching_hybrid:".len()..]; + + // BP uses non-decomposed DEM, matching uses decomposed. + let bp = pecos_decoders::BpUfDecoder::from_dual_dem( + full_dem, + dem, + pecos_decoders::BpUfConfig::balanced(), + ) + .map_err(|e| PyErr::new::(e.to_string()))?; + + // Build Fusion Blossom from decomposed DEM. + let graph = DemMatchingGraph::from_dem_str(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + let config = FusionBlossomConfig { + num_nodes: Some(graph.num_detectors), + num_observables: graph.num_observables, + ..Default::default() + }; + let mut fb = FusionBlossomDecoder::new(config) + .map_err(|e| PyErr::new::(e.to_string()))?; + let mut edge_index_map = std::collections::BTreeMap::new(); + for (idx, edge) in graph.edges.iter().enumerate() { + let obs: Vec = edge.observables.iter().map(|&o| o as usize).collect(); + let key = if let Some(n2) = edge.node2 { + fb.add_edge(edge.node1 as usize, n2 as usize, &obs, Some(edge.weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + if edge.node1 <= n2 { + (edge.node1, n2) + } else { + (n2, edge.node1) + } + } else { + fb.add_boundary_edge(edge.node1 as usize, &obs, Some(edge.weight)) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + (edge.node1, u32::MAX) + }; + edge_index_map.insert(key, idx); + } + let corr_table = + CorrelationTable::from_dem_str(dem, &edge_index_map, graph.edges.len()).map_err( + |e| PyErr::new::(e.to_string()), + )?; + + Ok(Box::new(BpMatchingDecoder::with_correlations( + fb, bp, corr_table, + ))) + } + s if s.starts_with("windowed") => { + // Windowed decoder: "windowed" or "windowed:step=N,buf=M,inner=TYPE,mode=MODE" + // inner= takes the REST of the string (supports nested specs with commas). + let mut config = pecos_decoders::WindowedConfig::default(); + let mut inner_type = "pecos_uf".to_string(); + let mut mode = String::new(); + if let Some(params) = s.strip_prefix("windowed:") { + // Split inner= from the rest: "step=5,buf=5,inner=perturbed:K=7,sigma=0.5" + // → params before inner, inner spec + let (own_params, inner_spec) = if let Some(idx) = params.find(",inner=") { + (¶ms[..idx], Some(¶ms[idx + 7..])) + } else if let Some(idx) = params.find("inner=") { + (¶ms[..idx.saturating_sub(1)], Some(¶ms[idx + 6..])) + } else { + (params, None) + }; + if let Some(spec) = inner_spec { + inner_type = spec.to_string(); + } + for kv in own_params.split(',') { + let parts: Vec<&str> = kv.splitn(2, '=').collect(); + if parts.len() == 2 { + match parts[0] { + "step" => config.step_size = parts[1].parse().unwrap_or(0), + "buf" | "buffer" => config.buffer_size = parts[1].parse().unwrap_or(0), + "mode" => mode = parts[1].to_string(), + "seam" => config.seam_half_width = parts[1].parse().unwrap_or(0), + "ext" | "core_extend" => { + config.core_extend = parts[1].parse().unwrap_or(0); + } + "wmax" | "commit_weight_max" => { + config.commit_weight_max = parts[1].parse().unwrap_or(0.0); + } + _ => {} + } + } + } + } + + if mode == "sandwich" || (mode.is_empty() && config.buffer_size > 0) { + // Sandwich decoder (two-phase): best accuracy with buf > 0. + // Default: buf=step, wmax=2.5, PM residual decoder. + if config.buffer_size == 0 { + config.buffer_size = config.step_size; + } + if config.commit_weight_max == 0.0 { + config.commit_weight_max = 2.5; + } + let phase2_type = if inner_type == "pecos_uf" { + "pymatching".to_string() + } else { + inner_type.clone() + }; + let phase1_factory = |sub_dem: &str| -> Result< + pecos_decoders::UfDecoder, + pecos_decoders::DecoderError, + > { + pecos_decoders::UfDecoder::from_dem( + sub_dem, + pecos_decoders::UfDecoderConfig::windowed(), + ) + }; + let phase2_factory = |sub_dem: &str| -> Result< + Box, + pecos_decoders::DecoderError, + > { + create_observable_decoder(sub_dem, &phase2_type) + .map_err(|e| pecos_decoders::DecoderError::InternalError(e.to_string())) + }; + let dec = pecos_decoders::SandwichWindowedDecoder::from_dem( + dem, + config, + phase1_factory, + phase2_factory, + ) + .map_err(|e| PyErr::new::(e.to_string()))?; + Ok(Box::new(dec)) + } else if mode == "overlap" { + // Single-phase overlapping (UF by default). + let factory = |sub_dem: &str| -> Result< + pecos_decoders::UfDecoder, + pecos_decoders::DecoderError, + > { + pecos_decoders::UfDecoder::from_dem( + sub_dem, + pecos_decoders::UfDecoderConfig::windowed(), + ) + }; + let dec = + pecos_decoders::OverlappingWindowedDecoder::from_dem(dem, config, factory) + .map_err(|e| { + PyErr::new::(e.to_string()) + })?; + Ok(Box::new(dec)) + } else { + // Non-overlapping with pluggable inner decoder. + let factory = |sub_dem: &str| -> Result< + Box, + pecos_decoders::DecoderError, + > { + create_observable_decoder(sub_dem, &inner_type) + .map_err(|e| pecos_decoders::DecoderError::InternalError(e.to_string())) + }; + let dec = pecos_decoders::WindowedDecoder::from_dem(dem, config, factory).map_err( + |e| PyErr::new::(e.to_string()), + )?; + Ok(Box::new(dec)) + } + } + "pecos_uf:accurate" => { + // UIUF CSS-aware mode. Single-DEM path falls back to balanced. + // For proper UIUF, use CssUfDecoder directly with separate X/Z DEMs + // via the PyCssUfDecoder Python class. + create_observable_decoder(dem, "pecos_uf:balanced") + } + "mwpf" => { + let d = + pecos_decoders::MwpfDecoder::from_dem(dem, pecos_decoders::MwpfConfig::default()) + .map_err(|e| PyErr::new::(e.to_string()))?; + Ok(Box::new(d)) + } + s if s.starts_with("mwpf:") => { + // Parse "mwpf:key=val,key=val" config overrides. + // Keys: c/cluster_node_limit, t/timeout, once/only_solve_primal_once, solver + let mut config = pecos_decoders::MwpfConfig::default(); + for kv in s[5..].split(',') { + let parts: Vec<&str> = kv.splitn(2, '=').collect(); + if parts.len() != 2 { + continue; + } + match parts[0] { + "c" | "cluster_node_limit" => { + config.cluster_node_limit = parts[1].parse().unwrap_or(50); + } + "t" | "timeout" => { + config.timeout = parts[1].parse().ok(); + } + "once" | "only_solve_primal_once" => { + config.only_solve_primal_once = parts[1] == "true" || parts[1] == "1"; + } + "solver" => { + config.solver_type = match parts[1] { + "uf" | "union_find" => pecos_decoders::MwpfSolverType::UnionFind, + "sh" | "single_hair" => pecos_decoders::MwpfSolverType::SingleHair, + "bp" | "bp_hybrid" => pecos_decoders::MwpfSolverType::BpHybrid, + _ => pecos_decoders::MwpfSolverType::JointSingleHair, + }; + } + _ => {} + } + } + let d = pecos_decoders::MwpfDecoder::from_dem(dem, config) + .map_err(|e| PyErr::new::(e.to_string()))?; + Ok(Box::new(d)) + } + s if s.starts_with("perturbed") => { + // Perturbed-weight ensemble: "perturbed" or "perturbed:K=15,sigma=0.7,inner=TYPE" + // inner= takes the REST of the string (supports nested decoder specs). + use pecos_decoder_core::perturbed::{PerturbedConfig, build_perturbed_ensemble}; + + let mut config = PerturbedConfig::default(); + let mut inner_type = "pymatching".to_string(); + if let Some(params) = s.strip_prefix("perturbed:") { + // Extract inner= (takes rest of string for nesting support) + let (own_params, inner_spec) = if let Some(idx) = params.find(",inner=") { + (¶ms[..idx], Some(¶ms[idx + 7..])) + } else if let Some(idx) = params.find("inner=") { + (¶ms[..idx.saturating_sub(1)], Some(¶ms[idx + 6..])) + } else { + (params, None) + }; + if let Some(spec) = inner_spec { + inner_type = spec.to_string(); + } + for kv in own_params.split(',') { + let parts: Vec<&str> = kv.splitn(2, '=').collect(); + if parts.len() == 2 { + match parts[0] { + "K" | "k" => config.k = parts[1].parse().unwrap_or(15), + "sigma" | "s" => config.sigma = parts[1].parse().unwrap_or(0.7), + "seed" => config.seed = parts[1].parse().unwrap_or(42), + _ => {} + } + } + } + } + + let ensemble = build_perturbed_ensemble(dem, &config, |sub_dem| { + create_observable_decoder(sub_dem, &inner_type) + .map_err(|e| pecos_decoders::DecoderError::InternalError(e.to_string())) + }) + .map_err(|e| PyErr::new::(e.to_string()))?; + + Ok(Box::new(ensemble)) + } + s if s.starts_with("beamsearch") => { + // Beam search windowed decoder: "beamsearch" or "beamsearch:K=5,sigma=0.5,buf=5" + let mut config = pecos_decoders::BeamSearchConfig::default(); + if let Some(params) = s.strip_prefix("beamsearch:") { + for kv in params.split(',') { + let parts: Vec<&str> = kv.splitn(2, '=').collect(); + if parts.len() == 2 { + match parts[0] { + "K" | "k" => config.beam_width = parts[1].parse().unwrap_or(5), + "sigma" | "s" => { + config.perturbation_sigma = parts[1].parse().unwrap_or(0.5); + } + "seed" => config.seed = parts[1].parse().unwrap_or(42), + "step" => config.window.step_size = parts[1].parse().unwrap_or(0), + "buf" | "buffer" => { + config.window.buffer_size = parts[1].parse().unwrap_or(0); + } + "wmax" => { + config.window.commit_weight_max = parts[1].parse().unwrap_or(0.0); + } + _ => {} + } + } + } + } + // Match sandwich defaults: buf=step, wmax=2.5. + // When step=0 (auto), buf also needs to be auto. Set buf=5 as a + // reasonable default (will be auto-tuned by parse_dem_params). + if config.window.buffer_size == 0 { + if config.window.step_size > 0 { + config.window.buffer_size = config.window.step_size; + } else { + config.window.buffer_size = 5; // auto: will be refined by d_est + } + } + if config.window.commit_weight_max == 0.0 { + config.window.commit_weight_max = 2.5; + } + + let phase1_factory = |sub_dem: &str| -> Result< + pecos_decoders::UfDecoder, + pecos_decoders::DecoderError, + > { + pecos_decoders::UfDecoder::from_dem( + sub_dem, + pecos_decoders::UfDecoderConfig::windowed(), + ) + }; + let phase2_factory = |sub_dem: &str| -> Result< + Box, + pecos_decoders::DecoderError, + > { + create_observable_decoder(sub_dem, "pymatching") + .map_err(|e| pecos_decoders::DecoderError::InternalError(e.to_string())) + }; + let dec = pecos_decoders::BeamSearchWindowedDecoder::from_dem( + dem, + config, + phase1_factory, + Some(phase2_factory), + ) + .map_err(|e| PyErr::new::(e.to_string()))?; + Ok(Box::new(dec)) + } + s if s.starts_with("ensemble:") => { + // Parse "ensemble:dec1,dec2,dec3" -- create multiple decoders and vote. + use pecos_decoder_core::ensemble::EnsembleDecoder; + let members_str = &s[9..]; + let mut members: Vec> = Vec::new(); + for spec in members_str.split(',') { + let spec = spec.trim(); + if spec.is_empty() { + continue; + } + members.push(create_observable_decoder(dem, spec)?); + } + if members.is_empty() { + return Err(PyErr::new::( + "ensemble: needs at least one decoder", + )); + } + Ok(Box::new(EnsembleDecoder::new(members))) + } + // Per-observable subgraph decoder: requires stab_coords from Python. + // This is NOT callable from the string-based create_observable_decoder API. + // Use the Python ObservableSubgraphDecoder class directly instead. + s if s == "observable_subgraph" || s.starts_with("observable_subgraph:") => { + Err(PyErr::new::( + "observable_subgraph decoder requires stab_coords. \ + Use pecos_rslib.qec.ObservableSubgraphDecoder class directly.", + )) + } + _ => Err(PyErr::new::(format!( + "Unsupported decoder_type: {decoder_type}. \ + Supported: pymatching, tesseract, mwpf, pecos_uf (or pecos_uf:fast/balanced/accurate), \ + observable_subgraph, ensemble:d1,d2,..., bp_osd, bp_lsd, union_find, relay_bp, min_sum_bp." + ))), } +} - /// Sample multiple shots of measurement outcomes. - /// - /// Args: - /// `num_shots`: Number of shots to sample. - /// seed: Optional random seed for reproducibility. - /// - /// Returns: - /// List of lists, where each inner list contains boolean measurement outcomes. - #[pyo3(signature = (num_shots, seed=None))] - fn sample_batch(&self, num_shots: usize, seed: Option) -> Vec> { - use pecos_random::PecosRng; - use rand::RngExt; +/// Pre-generated sample batch held in Rust memory. +/// +/// Created by `DemSampler.generate_samples()`. Can be decoded by multiple +/// decoders without re-sampling, and without crossing the Rust/Python boundary +/// per shot. +/// +/// # Example +/// +/// ```python +/// samples = sampler.generate_samples(10000, seed=42) +/// pm_errors = samples.decode_count(dem, "pymatching") +/// ts_errors = samples.decode_count(dem, "tesseract") +/// # Both decoders ran on the exact same samples. +/// ``` +#[pyclass(name = "SampleBatch", module = "pecos_rslib.qec")] +pub struct PySampleBatch { + /// Columnar bit-packed detector columns: det_columns[det_idx][word_idx] + det_columns: Vec>, + /// Columnar bit-packed observable columns: obs_columns[obs_idx][word_idx] + obs_columns: Vec>, + num_detectors: usize, + num_shots: usize, +} - let mut rng = match seed { - Some(s) => PecosRng::seed_from_u64(s), - None => PecosRng::seed_from_u64(rand::rng().random()), - }; +impl PySampleBatch { + /// Extract syndrome for one shot into a pre-allocated buffer. + fn extract_syndrome(&self, shot: usize, buf: &mut [u8]) { + buf.fill(0); + let word_idx = shot / 64; + let bit_mask = 1u64 << (shot % 64); + for (det_idx, col) in self.det_columns.iter().enumerate() { + if col[word_idx] & bit_mask != 0 { + buf[det_idx] = 1; + } + } + } - (0..num_shots) - .map(|_| self.inner.sample(&mut rng)) - .collect() + /// Extract observable mask for one shot. + fn extract_obs_mask(&self, shot: usize) -> u64 { + let word_idx = shot / 64; + let bit_mask = 1u64 << (shot % 64); + let mut mask = 0u64; + for (obs_idx, col) in self.obs_columns.iter().enumerate() { + if col[word_idx] & bit_mask != 0 { + mask |= 1u64 << obs_idx; + } + } + mask } - /// Get all mechanisms and their probabilities. - /// - /// Returns: - /// List of (measurements, probability) tuples. - fn get_mechanisms(&self) -> Vec<(Vec, f64)> { - self.inner + /// Build from columnar data (from generate_samples). + fn from_columnar( + det_columns: Vec>, + obs_columns: Vec>, + num_shots: usize, + ) -> Self { + let num_detectors = det_columns.len(); + Self { + det_columns, + obs_columns, + num_detectors, + num_shots, + } + } + + /// Build from row-major data (from Python constructor). + fn from_row_major(detection_events: Vec>, observable_masks: Vec) -> Self { + let num_shots = detection_events.len(); + let num_detectors = detection_events.first().map_or(0, |r| r.len()); + let num_words = num_shots.div_ceil(64); + + // Convert row-major → columnar + let mut det_columns = vec![vec![0u64; num_words]; num_detectors]; + for (shot, row) in detection_events.iter().enumerate() { + let word_idx = shot / 64; + let bit_mask = 1u64 << (shot % 64); + for (det_idx, &val) in row.iter().enumerate() { + if val != 0 { + det_columns[det_idx][word_idx] |= bit_mask; + } + } + } + + // Find max observable index + let max_obs = observable_masks .iter() - .map(|(m, &p)| (m.measurements.to_vec(), p)) - .collect() + .map(|m| 64 - m.leading_zeros() as usize) + .max() + .unwrap_or(0); + let mut obs_columns = vec![vec![0u64; num_words]; max_obs]; + for (shot, &mask) in observable_masks.iter().enumerate() { + let word_idx = shot / 64; + let bit_mask = 1u64 << (shot % 64); + for obs_idx in 0..max_obs { + if mask & (1u64 << obs_idx) != 0 { + obs_columns[obs_idx][word_idx] |= bit_mask; + } + } + } + + Self { + det_columns, + obs_columns, + num_detectors, + num_shots, + } } +} - /// Convert measurement outcomes to detection events. +#[pymethods] +impl PySampleBatch { + /// Build a SampleBatch from detection event arrays and observable masks. /// - /// Given raw measurement outcomes and detector definitions, computes which - /// detectors fire by XOR'ing the specified measurement records for each detector. + /// Args: + /// detection_events: List of syndromes, each a list of u8 (0/1). + /// observable_masks: List of u64 true observable flip masks. + #[new] + #[pyo3(signature = (detection_events, observable_masks))] + fn new(detection_events: Vec>, observable_masks: Vec) -> PyResult { + if detection_events.len() != observable_masks.len() { + return Err(pyo3::exceptions::PyValueError::new_err(format!( + "detection_events ({}) and observable_masks ({}) must have same length", + detection_events.len(), + observable_masks.len(), + ))); + } + let expected_len = detection_events.first().map_or(0, |r| r.len()); + for (i, row) in detection_events.iter().enumerate() { + if row.len() != expected_len { + return Err(pyo3::exceptions::PyValueError::new_err(format!( + "detection_events row {i} has length {} but expected {expected_len} \ + (matching row 0)", + row.len() + ))); + } + } + Ok(Self::from_row_major(detection_events, observable_masks)) + } + + /// Number of shots in this batch. + #[getter] + fn num_shots(&self) -> usize { + self.num_shots + } + + /// Get the syndrome for shot `i` as a list of u8 values. + fn get_syndrome(&self, i: usize) -> PyResult> { + if i >= self.num_shots { + return Err(PyErr::new::(format!( + "Shot index {i} out of range (num_shots={})", + self.num_shots + ))); + } + let mut buf = vec![0u8; self.num_detectors]; + self.extract_syndrome(i, &mut buf); + Ok(buf) + } + + /// Get the expected observable mask for shot `i`. + fn get_observable_mask(&self, i: usize) -> PyResult { + if i >= self.num_shots { + return Err(PyErr::new::(format!( + "Shot index {i} out of range (num_shots={})", + self.num_shots + ))); + } + Ok(self.extract_obs_mask(i)) + } + + /// Decode all samples with the given decoder type and return the error count. /// - /// If measurement order was provided when building the MNM, outcomes are first - /// reordered from influence map order to `TickCircuit` order before applying - /// detector records. + /// This runs entirely in Rust -- no per-shot Python crossing. /// /// Args: - /// outcomes: List of boolean measurement outcomes (from `sample()`). - /// `detectors_json`: JSON string with detector definitions. - /// Format: [{"id": 0, "records": [-1, -5]}, ...] - /// Records are negative offsets from end of measurement list. + /// dem: DEM string (Stim format) for the decoder. + /// `decoder_type`: "pymatching", "tesseract", "`bp_osd`", "`bp_lsd`", "`union_find`", + /// "`relay_bp`", or "`min_sum_bp`". /// /// Returns: - /// List of boolean detection events (True = detector fired). - /// - /// Example: - /// >>> outcomes = `mnm.sample()` - /// >>> `detection_events` = `mnm.to_detection_events(outcomes`, `detectors_json`) - fn to_detection_events( - &self, - outcomes: Vec, - detectors_json: &str, - ) -> PyResult> { - let detector_records = parse_detector_records(detectors_json)?; - // Use instance method which applies im_to_tc reordering if set - Ok(self - .inner - .compute_detection_events(&outcomes, &detector_records)) + /// Number of logical errors. + #[pyo3(signature = (dem, decoder_type="pymatching"))] + fn decode_count(&self, dem: &str, decoder_type: &str) -> PyResult { + let mut decoder = create_observable_decoder(dem, decoder_type)?; + let mut errors = 0usize; + let mut syndrome = vec![0u8; self.num_detectors]; + for i in 0..self.num_shots { + self.extract_syndrome(i, &mut syndrome); + let predicted = decoder.decode_to_observables(&syndrome).unwrap_or(u64::MAX); + if predicted != self.extract_obs_mask(i) { + errors += 1; + } + } + Ok(errors) } - /// Sample and convert to detection events in one step. + /// Parallel decode: distributes samples across rayon workers. /// - /// This is a convenience method that combines `sample()` and `to_detection_events()`. + /// Each worker creates its own decoder instance. Faster for slow decoders. /// /// Args: - /// `detectors_json`: JSON string with detector definitions. - /// seed: Optional random seed for reproducibility. + /// dem: DEM string for the decoder. + /// `decoder_type`: Decoder type string. + /// `num_workers`: Number of parallel workers (default: number of CPUs). /// /// Returns: - /// Tuple of (`measurement_outcomes`, `detection_events`). - #[pyo3(signature = (detectors_json, seed=None))] - fn sample_with_detectors( + /// Number of logical errors. + #[pyo3(signature = (dem, decoder_type="pymatching", num_workers=None))] + fn decode_count_parallel( &self, - detectors_json: &str, - seed: Option, - ) -> PyResult<(Vec, Vec)> { - use pecos_random::PecosRng; - use rand::RngExt; - - let detector_records = parse_detector_records(detectors_json)?; - - let mut rng = match seed { - Some(s) => PecosRng::seed_from_u64(s), - None => PecosRng::seed_from_u64(rand::rng().random()), - }; + dem: &str, + decoder_type: &str, + num_workers: Option, + ) -> PyResult { + use rayon::prelude::*; + + let n_workers = num_workers.unwrap_or_else(rayon::current_num_threads); + let pool = rayon::ThreadPoolBuilder::new() + .num_threads(n_workers) + .build() + .map_err(|e| PyErr::new::(e.to_string()))?; + + let dem_str = dem.to_string(); + let dt = decoder_type.to_string(); + let n = self.num_shots; + let num_dets = self.num_detectors; + + // Materialize row-major data for parallel decode. + let detection_events: Vec> = (0..n) + .map(|i| { + let mut s = vec![0u8; num_dets]; + self.extract_syndrome(i, &mut s); + s + }) + .collect(); + let observable_masks: Vec = (0..n).map(|i| self.extract_obs_mask(i)).collect(); + + let total_errors: usize = pool.install(|| { + (0..n) + .into_par_iter() + .map_init( + || create_observable_decoder(&dem_str, &dt).unwrap(), + |decoder, i| { + let predicted = decoder + .decode_to_observables(&detection_events[i]) + .unwrap_or(u64::MAX); + usize::from(predicted != observable_masks[i]) + }, + ) + .sum() + }); - let (outcomes, detection_events) = self - .inner - .sample_with_detectors(&detector_records, &mut rng); - Ok((outcomes, detection_events)) + Ok(total_errors) } - /// Sample multiple shots and convert to detection events. + /// Batch decode all samples at once using `PyMatching`'s batch API. /// - /// Args: - /// `num_shots`: Number of shots to sample. - /// `detectors_json`: JSON string with detector definitions. - /// seed: Optional random seed for reproducibility. + /// Sends all detection events in a single flat array to the decoder, + /// which can vectorize across shots. Faster than per-shot decode for + /// `PyMatching`. Only supports pymatching decoder. /// /// Returns: - /// List of (`measurement_outcomes`, `detection_events`) tuples. - #[pyo3(signature = (num_shots, detectors_json, seed=None))] - fn sample_batch_with_detectors( - &self, - num_shots: usize, - detectors_json: &str, - seed: Option, - ) -> PyResult, Vec)>> { - use pecos_random::PecosRng; - use rand::RngExt; - - let detector_records = parse_detector_records(detectors_json)?; + /// Number of logical errors. + #[pyo3(signature = (dem))] + fn decode_count_batch(&self, dem: &str) -> PyResult { + use pecos_decoders::{BatchConfig, PyMatchingDecoder}; + + let mut decoder = PyMatchingDecoder::from_dem(dem) + .map_err(|e| PyErr::new::(e.to_string()))?; + + let num_detectors = decoder.num_detectors(); + + // Flatten all detection events into a single contiguous array + let mut flat = Vec::with_capacity(self.num_shots * num_detectors); + let mut syndrome = vec![0u8; self.num_detectors]; + for i in 0..self.num_shots { + self.extract_syndrome(i, &mut syndrome); + // Pad or truncate to decoder's num_detectors + let take = syndrome.len().min(num_detectors); + flat.extend_from_slice(&syndrome[..take]); + for _ in take..num_detectors { + flat.push(0); + } + } - let mut rng = match seed { - Some(s) => PecosRng::seed_from_u64(s), - None => PecosRng::seed_from_u64(rand::rng().random()), + let config = BatchConfig { + bit_packed_input: false, + bit_packed_output: false, + return_weights: false, }; - let results: Vec<_> = (0..num_shots) - .map(|_| { - self.inner - .sample_with_detectors(&detector_records, &mut rng) - }) - .collect(); + let result = decoder + .decode_batch_with_config(&flat, self.num_shots, num_detectors, config) + .map_err(|e| PyErr::new::(e.to_string()))?; + + // Count errors by comparing predictions to true observable masks + let num_observables = decoder.num_observables(); + let mut num_errors = 0usize; + for (i, prediction) in result.predictions.iter().enumerate() { + let mut predicted_mask = 0u64; + for (j, &v) in prediction.iter().enumerate() { + if v != 0 && j < num_observables { + predicted_mask |= 1 << j; + } + } + if predicted_mask != self.extract_obs_mask(i) { + num_errors += 1; + } + } - Ok(results) + Ok(num_errors) } - /// Sample for threshold estimation with both detection events and observable flips. + /// Decode all samples and collect per-shot timing statistics. /// - /// This matches Stim's DEM sampler output format, returning the information - /// needed for decoding and logical error rate computation. + /// Returns a `DecodeStats` with error count, total time, median, and + /// percentile per-shot decode times. Useful for understanding decoder + /// performance characteristics (heavy tails, etc.). /// /// Args: - /// `detectors_json`: JSON string with detector definitions. - /// `observables_json`: JSON string with observable definitions. - /// seed: Optional random seed for reproducibility. + /// dem: DEM string for the decoder. + /// `decoder_type`: Decoder type string. /// /// Returns: - /// Tuple of (`detection_events`, `observable_flips`). - #[pyo3(signature = (detectors_json, observables_json, seed=None))] - fn sample_for_decoding( - &self, - detectors_json: &str, - observables_json: &str, - seed: Option, - ) -> PyResult<(Vec, Vec)> { - use pecos_random::PecosRng; - use rand::RngExt; - - let detector_records = parse_detector_records(detectors_json)?; - let observable_records = parse_observable_records(observables_json)?; - - let mut rng = match seed { - Some(s) => PecosRng::seed_from_u64(s), - None => PecosRng::seed_from_u64(rand::rng().random()), - }; + /// `DecodeStats` with timing breakdown. + #[pyo3(signature = (dem, decoder_type="pymatching"))] + fn decode_stats(&self, dem: &str, decoder_type: &str) -> PyResult { + use std::time::Instant; + + let mut decoder = create_observable_decoder(dem, decoder_type)?; + let mut num_errors = 0usize; + let mut per_shot_seconds: Vec = Vec::with_capacity(self.num_shots); + let mut syndrome = vec![0u8; self.num_detectors]; + + for i in 0..self.num_shots { + self.extract_syndrome(i, &mut syndrome); + let t0 = Instant::now(); + let predicted = decoder.decode_to_observables(&syndrome).unwrap_or(u64::MAX); + let elapsed = t0.elapsed().as_secs_f64(); + per_shot_seconds.push(elapsed); + if predicted != self.extract_obs_mask(i) { + num_errors += 1; + } + } - let (detection_events, observable_flips) = - self.inner - .sample_for_decoding(&detector_records, &observable_records, &mut rng); - Ok((detection_events, observable_flips)) + Ok(PyDecodeStats::from_times( + self.num_shots, + num_errors, + per_shot_seconds, + )) } - /// Batch sample for threshold estimation. + /// Decode all shots with per-shot timing, using parallel workers. /// - /// Efficiently samples multiple shots, returning detection events and observable - /// flips for each shot. This is the PECOS native alternative to Stim's DEM sampler. + /// Like `decode_stats` but distributes shots across rayon threads. + /// Useful for slow decoders (MWPF, Tesseract, BP+OSD) where a single + /// shot can take seconds. /// - /// Args: - /// `num_shots`: Number of shots to sample. - /// `detectors_json`: JSON string with detector definitions. - /// `observables_json`: JSON string with observable definitions. - /// seed: Optional random seed for reproducibility. + /// Per-shot timing is still collected (each worker times its own shots). + /// The total wall-clock time is approximately `serial_total / num_workers`. /// - /// Returns: - /// Tuple of (`detection_events_per_shot`, `observable_flips_per_shot`) as numpy-compatible lists. - #[pyo3(signature = (num_shots, detectors_json, observables_json, seed=None))] - fn sample_batch_for_decoding( + /// Args: + /// dem: DEM string for the decoder. + /// `decoder_type`: Decoder type string. + /// `num_workers`: Number of parallel workers (default: number of CPUs). + #[pyo3(signature = (dem, decoder_type="mwpf", num_workers=None))] + fn decode_stats_parallel( &self, - num_shots: usize, - detectors_json: &str, - observables_json: &str, - seed: Option, - ) -> PyResult { - use pecos_random::PecosRng; - use rand::RngExt; + dem: &str, + decoder_type: &str, + num_workers: Option, + ) -> PyResult { + use rayon::prelude::*; + + let n_workers = num_workers.unwrap_or_else(rayon::current_num_threads); + + // Validate decoder type early. + create_observable_decoder(dem, decoder_type)?; + + let pool = rayon::ThreadPoolBuilder::new() + .num_threads(n_workers) + .build() + .map_err(|e| PyErr::new::(e.to_string()))?; + + let dem_str = dem.to_string(); + let dt = decoder_type.to_string(); + let num_dets = self.num_detectors; + + // Materialize row-major data for parallel decode. + let detection_events: Vec> = (0..self.num_shots) + .map(|i| { + let mut s = vec![0u8; num_dets]; + self.extract_syndrome(i, &mut s); + s + }) + .collect(); + let observable_masks: Vec = (0..self.num_shots) + .map(|i| self.extract_obs_mask(i)) + .collect(); - let detector_records = parse_detector_records(detectors_json)?; - let observable_records = parse_observable_records(observables_json)?; + // Each worker decodes a slice of shots and returns (errors, per_shot_times). + let results: Vec<(usize, Vec)> = pool.install(|| { + let chunk_size = self.num_shots.div_ceil(n_workers); + (0..n_workers) + .into_par_iter() + .map(|worker_id| { + let start = worker_id * chunk_size; + let end = (start + chunk_size).min(self.num_shots); + if start >= end { + return (0, Vec::new()); + } - let mut rng = match seed { - Some(s) => PecosRng::seed_from_u64(s), - None => PecosRng::seed_from_u64(rand::rng().random()), - }; + let mut decoder = create_observable_decoder(&dem_str, &dt).unwrap(); + let mut errors = 0usize; + let mut times = Vec::with_capacity(end - start); + + for i in start..end { + let t0 = std::time::Instant::now(); + let predicted = decoder + .decode_to_observables(&detection_events[i]) + .unwrap_or(u64::MAX); + times.push(t0.elapsed().as_secs_f64()); + if predicted != observable_masks[i] { + errors += 1; + } + } + (errors, times) + }) + .collect() + }); - let (all_detection_events, all_observable_flips) = self.inner.sample_batch_for_decoding( - num_shots, - &detector_records, - &observable_records, - &mut rng, - ); + let mut total_errors = 0usize; + let mut all_times = Vec::with_capacity(self.num_shots); + for (errs, times) in results { + total_errors += errs; + all_times.extend(times); + } - Ok((all_detection_events, all_observable_flips)) + Ok(PyDecodeStats::from_times( + self.num_shots, + total_errors, + all_times, + )) } fn __repr__(&self) -> String { - format!( - "MeasurementNoiseModel(mechanisms={}, measurements={})", - self.num_mechanisms(), - self.num_measurements() - ) + format!("SampleBatch(num_shots={})", self.num_shots) } } -// --- Noisy Sampler (DEM-style sampling) --- +/// Per-shot decode timing statistics. +#[pyclass(name = "DecodeStats", module = "pecos_rslib.qec", skip_from_py_object)] +#[derive(Clone)] +pub struct PyDecodeStats { + #[pyo3(get)] + pub num_shots: usize, + #[pyo3(get)] + pub num_errors: usize, + #[pyo3(get)] + pub logical_error_rate: f64, + #[pyo3(get)] + pub total_seconds: f64, + #[pyo3(get)] + pub per_shot_mean: f64, + #[pyo3(get)] + pub per_shot_median: f64, + #[pyo3(get)] + pub per_shot_p99: f64, + #[pyo3(get)] + pub per_shot_min: f64, + #[pyo3(get)] + pub per_shot_max: f64, + /// Quantile summary for distribution visualization (violin plots). + /// 21 values at percentiles [0, 5, 10, 15, ..., 90, 95, 100]. + #[pyo3(get)] + pub quantiles: Vec, +} -/// Fast noisy sampler for threshold estimation. -/// -/// This is essentially a DEM sampler - it samples fault locations and uses -/// the influence map to determine detector and logical effects. This is the -/// recommended approach for threshold estimation as it directly samples -/// detector flips and observable flips without intermediate steps. -/// -/// Two modes are supported: -/// - Uniform noise: Same error probability at all locations (fast) -/// - Circuit-level noise: Per-gate-type probabilities (p1, p2, `p_meas`, `p_init`) -/// -/// # Example -/// -/// ```python -/// from pecos_rslib.qec import DagFaultAnalyzer, NoisySampler -/// -/// # Build influence map -/// analyzer = DagFaultAnalyzer(dag) -/// influence_map = analyzer.build_influence_map() -/// -/// # Uniform noise (simple) -/// sampler = NoisySampler(influence_map, p_error=0.01, seed=42) -/// -/// # Circuit-level noise (accurate) -/// sampler = NoisySampler.with_circuit_noise( -/// influence_map, p1=0.001, p2=0.01, p_meas=0.01, p_init=0.001, seed=42 -/// ) -/// -/// # Sample for threshold estimation -/// det_events, obs_flips = sampler.sample_batch(num_shots=10000) -/// ``` -#[pyclass(name = "NoisySampler", module = "pecos_rslib.qec")] -pub struct PyNoisySampler { - /// Owned influence map (cloned from input). - influence_map: RustDagFaultInfluenceMap, - /// Per-location error probabilities (for circuit-level noise). - per_location_probs: Vec, - /// RNG seed. - seed: u64, +impl PyDecodeStats { + // Shot counts and error counts are well within f64 mantissa range (2^52). + // Percentile index computation is bounded by array length. + #[allow( + clippy::cast_precision_loss, + clippy::cast_possible_truncation, + clippy::cast_sign_loss + )] + fn from_times(num_shots: usize, num_errors: usize, mut times: Vec) -> Self { + let total_seconds: f64 = times.iter().sum(); + let per_shot_mean = if num_shots > 0 { + total_seconds / num_shots as f64 + } else { + 0.0 + }; + + times.sort_by(|a, b| a.partial_cmp(b).unwrap_or(std::cmp::Ordering::Equal)); + + let percentile = |p: f64| -> f64 { + if times.is_empty() { + return 0.0; + } + let idx = (p / 100.0 * (times.len() - 1) as f64).round() as usize; + times[idx.min(times.len() - 1)] + }; + + // 21 quantiles at [0, 5, 10, ..., 95, 100] for violin plots + let quantiles: Vec = (0..=20).map(|i| percentile(f64::from(i) * 5.0)).collect(); + + Self { + num_shots, + num_errors, + logical_error_rate: if num_shots > 0 { + num_errors as f64 / num_shots as f64 + } else { + 0.0 + }, + total_seconds, + per_shot_mean, + per_shot_median: percentile(50.0), + per_shot_p99: percentile(99.0), + per_shot_min: times.first().copied().unwrap_or(0.0), + per_shot_max: times.last().copied().unwrap_or(0.0), + quantiles, + } + } +} + +#[pymethods] +impl PyDecodeStats { + fn __repr__(&self) -> String { + format!( + "DecodeStats(shots={}, errors={}, LER={:.4}, median={:.2e}s, p99={:.2e}s, max={:.2e}s)", + self.num_shots, + self.num_errors, + self.logical_error_rate, + self.per_shot_median, + self.per_shot_p99, + self.per_shot_max, + ) + } +} + +#[pyclass(name = "DemSampler", module = "pecos_rslib.qec")] +pub struct PyDemSampler { + inner: RustNewDemSampler, } #[pymethods] -impl PyNoisySampler { - /// Create a new noisy sampler with uniform error probability. +impl PyDemSampler { + /// Build a sampler directly from a circuit and noise parameters. + /// + /// This is the simplest path: builds the influence map, extracts + /// annotations, and configures the sampler in one step. /// /// Args: - /// `influence_map`: A `DagFaultInfluenceMap` from `DagFaultAnalyzer` or `InfluenceBuilder`. - /// `p_error`: Uniform depolarizing error probability per fault location. - /// seed: Random seed for reproducibility. - #[new] - #[pyo3(signature = (influence_map, p_error, seed=None))] - fn new(influence_map: &PyDagFaultInfluenceMap, p_error: f64, seed: Option) -> Self { - use rand::RngExt; - let actual_seed = seed.unwrap_or_else(|| rand::rng().random()); - let num_locations = influence_map.inner.locations.len(); - Self { - influence_map: influence_map.inner.clone(), - per_location_probs: vec![p_error; num_locations], - seed: actual_seed, + /// circuit: A `DagCircuit` with gates and annotations. + /// p1: Single-qubit depolarizing error rate. + /// p2: Two-qubit depolarizing error rate. + /// `p_meas`: Measurement error rate. + /// `p_prep`: Initialization error rate. + /// `p_idle`: Optional idle noise rate per time unit. + /// + /// Example: + /// >>> sampler = DemSampler.from_circuit(dag, p1=0.001, p2=0.01) + /// >>> sampler = DemSampler.from_circuit(tc, p2=0.01) # TickCircuit also works + #[staticmethod] + #[pyo3(signature = (circuit, p1=0.001, p2=0.01, p_meas=0.001, p_prep=0.001, p_idle=None, idle_rz=None))] + fn from_circuit( + circuit: &Bound<'_, pyo3::PyAny>, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + p_idle: Option, + idle_rz: Option, + ) -> PyResult { + let mut noise = NoiseConfig::new(p1, p2, p_meas, p_prep); + noise.p_idle = p_idle.unwrap_or(0.0); + if let Some(rz) = idle_rz { + noise = noise.set_idle_rz(rz); + } + + // Accept both DagCircuit and TickCircuit + if let Ok(dag) = + circuit.extract::>() + { + let inner = RustNewDemSampler::from_circuit(&dag.inner, noise) + .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))?; + Ok(Self { inner }) + } else if let Ok(tc) = + circuit.extract::>() + { + let inner = RustNewDemSampler::from_tick_circuit(&tc.inner, noise) + .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))?; + Ok(Self { inner }) + } else { + Err(pyo3::exceptions::PyTypeError::new_err( + "from_circuit() expects a DagCircuit or TickCircuit", + )) + } + } + + /// Create a sampler from a Stim-format DEM string. + /// + /// Parses `error(p) D0 D3 L0` lines and builds a sampling engine. + /// Useful for sampling from DEMs produced by EEG analysis. + /// + /// Example: + /// >>> from pecos_rslib_exp import eeg_heisenberg_dem + /// >>> dem_str = eeg_heisenberg_dem(tc, idle_rz=0.05) + /// >>> sampler = DemSampler.from_dem_string(dem_str) + /// >>> results = sampler.sample_batch(shots=1000000) + #[staticmethod] + #[pyo3(signature = (dem_string))] + fn from_dem_string(dem_string: &str) -> PyResult { + use pecos_qec::fault_tolerance::dem_builder::SamplingEngine; + + let mut mechanisms = Vec::new(); + let mut max_det = 0u32; + let mut max_obs = 0u32; + + for line in dem_string.lines() { + let line = line.trim(); + if line.is_empty() || line.starts_with('#') { + continue; + } + + // Parse: error(prob) D0 D3 L0 + if let Some(rest) = line.strip_prefix("error(") { + if let Some(paren_end) = rest.find(')') { + let prob: f64 = rest[..paren_end].parse().map_err(|e| { + pyo3::exceptions::PyValueError::new_err(format!("bad probability: {e}")) + })?; + let tokens = rest[paren_end + 1..].split_whitespace(); + let mut dets = Vec::new(); + let mut obs = Vec::new(); + for tok in tokens { + if let Some(d) = tok.strip_prefix('D') { + let id: u32 = d.parse().map_err(|e| { + pyo3::exceptions::PyValueError::new_err(format!( + "bad detector: {e}" + )) + })?; + dets.push(id); + max_det = max_det.max(id + 1); + } else if let Some(l) = tok.strip_prefix('L') { + let id: u32 = l.parse().map_err(|e| { + pyo3::exceptions::PyValueError::new_err(format!( + "bad observable: {e}" + )) + })?; + obs.push(id); + max_obs = max_obs.max(id + 1); + } + } + if prob > 0.0 { + mechanisms.push((prob, dets, obs)); + } + } + } } + + let engine = + SamplingEngine::from_mechanisms(mechanisms, max_det as usize, max_obs as usize); + let inner = RustNewDemSampler::from_engine(engine); + Ok(Self { inner }) + } + + /// Create a sampler in raw measurement mode with uniform noise. + #[staticmethod] + #[pyo3(signature = (influence_map, p_error))] + fn raw_uniform(influence_map: &PyDagFaultInfluenceMap, p_error: f64) -> PyResult { + Self::from_influence_map(influence_map, p_error) + } + + /// Create a sampler in raw measurement mode with circuit-level noise. + #[staticmethod] + #[pyo3(signature = (influence_map, p1, p2, p_meas, p_prep))] + fn raw( + influence_map: &PyDagFaultInfluenceMap, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + ) -> PyResult { + Self::from_influence_map_circuit_noise(influence_map, p1, p2, p_meas, p_prep) } - /// Create a sampler with circuit-level noise (different rates per gate type). + /// Create a sampler in detector-event mode. /// - /// This matches the noise model used by `DemBuilder` and Stim, with different - /// error probabilities for different gate types. + /// The `observables` argument defines observables. + #[staticmethod] + #[pyo3(signature = (influence_map, detectors, observables, p1, p2, p_meas, p_prep, p_idle=None, t1=None, t2=None))] + #[allow(clippy::too_many_arguments)] + fn with_detectors( + influence_map: &PyDagFaultInfluenceMap, + detectors: Vec>, + observables: Vec>, + p1: f64, + p2: f64, + p_meas: f64, + p_prep: f64, + p_idle: Option, + t1: Option, + t2: Option, + ) -> PyResult { + let mut noise = NoiseConfig::new(p1, p2, p_meas, p_prep); + noise.p_idle = p_idle.unwrap_or(0.0); + if let (Some(t1_val), Some(t2_val)) = (t1, t2) { + noise = noise.set_t1_t2(t1_val, t2_val); + } + let inner = RustNewDemSamplerBuilder::new(&influence_map.inner) + .with_noise_config(noise) + .with_detectors(detectors, observables) + .build() + .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))?; + Ok(Self { inner }) + } + + /// Create a sampler directly from an influence map with uniform noise. /// /// Args: /// `influence_map`: A `DagFaultInfluenceMap` from `DagFaultAnalyzer` or `InfluenceBuilder`. - /// p1: Single-qubit gate error probability. - /// p2: Two-qubit gate error probability. - /// `p_meas`: Measurement error probability. - /// `p_init`: Initialization/prep error probability. - /// seed: Random seed for reproducibility. + /// `p_error`: Uniform depolarizing error probability per fault location. #[staticmethod] - #[pyo3(signature = (influence_map, p1, p2, p_meas, p_init, seed=None))] - fn with_circuit_noise( + fn from_influence_map(influence_map: &PyDagFaultInfluenceMap, p_error: f64) -> PyResult { + let inner = RustNewDemSamplerBuilder::new(&influence_map.inner) + .with_uniform_noise(p_error) + .raw_measurements() + .build() + .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))?; + Ok(Self { inner }) + } + + /// Create a sampler from an influence map with circuit-level noise. + #[staticmethod] + fn from_influence_map_circuit_noise( influence_map: &PyDagFaultInfluenceMap, p1: f64, p2: f64, p_meas: f64, - p_init: f64, - seed: Option, - ) -> Self { - use pecos_quantum::GateType; - use rand::RngExt; + p_prep: f64, + ) -> PyResult { + let inner = RustNewDemSamplerBuilder::new(&influence_map.inner) + .with_noise(p1, p2, p_meas, p_prep) + .raw_measurements() + .build() + .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))?; + Ok(Self { inner }) + } - let actual_seed = seed.unwrap_or_else(|| rand::rng().random()); + /// Number of mechanisms in the sampler. + #[getter] + fn num_mechanisms(&self) -> usize { + self.inner.num_mechanisms() + } - // Build per-location probabilities based on gate type - let per_location_probs: Vec = influence_map - .inner - .locations - .iter() - .map(|loc| { - #[allow(clippy::match_same_arms)] // Explicitly list known single-qubit gates - match loc.gate_type { - GateType::PZ | GateType::QAlloc => p_init, - GateType::MZ | GateType::MeasureFree => p_meas, - GateType::CX | GateType::CZ | GateType::CY | GateType::SWAP => p2, - GateType::H - | GateType::SZ - | GateType::SZdg - | GateType::SX - | GateType::SXdg - | GateType::SY - | GateType::SYdg - | GateType::X - | GateType::Y - | GateType::Z - | GateType::T - | GateType::Tdg => p1, - _ => p1, // Default to p1 for unknown gates - } - }) - .collect(); + /// Number of output channels (detectors or measurements). + #[getter] + fn num_outputs(&self) -> usize { + self.inner.num_outputs() + } - Self { - influence_map: influence_map.inner.clone(), - per_location_probs, - seed: actual_seed, - } + /// Number of detectors (alias for `num_outputs`). + #[getter] + fn num_detectors(&self) -> usize { + self.inner.num_outputs() + } + + /// Number of observables when sampler metadata is known. + #[getter] + fn num_observables(&self) -> usize { + self.inner.num_observables() + } + + /// Total number of outputs in the DEM `L` namespace. + #[getter] + fn num_dem_outputs(&self) -> usize { + self.inner.num_dem_outputs() + } + + /// Number of tracked operators. + #[getter] + fn num_tracked_ops(&self) -> usize { + self.inner.num_tracked_ops() } /// Sample a single shot. /// + /// Args: + /// seed: Optional random seed for reproducibility. + /// /// Returns: - /// Tuple of (`detector_flips`, `logical_flips`) where each is a list of - /// indices that flipped. - fn sample_one(&mut self) -> (Vec, Vec) { - use pecos_qec::fault_tolerance::noisy_sampler::{NoisySampler, PerLocationNoiseModel}; + /// Tuple of (`detection_events`, `dem_output_flips`) as boolean lists. + #[pyo3(signature = (seed=None))] + fn sample(&self, seed: Option) -> (Vec, Vec) { + use pecos_random::PecosRng; + use rand::RngExt; - let noise_model = PerLocationNoiseModel::new(self.per_location_probs.clone()); - let mut sampler = NoisySampler::new(&self.influence_map, noise_model, self.seed); - let result = sampler.sample_one(); - // Update seed for next call - self.seed = self.seed.wrapping_add(1); - (result.detector_flips, result.logical_flips) + let mut rng = match seed { + Some(s) => PecosRng::seed_from_u64(s), + None => PecosRng::seed_from_u64(rand::rng().random()), + }; + + self.inner.sample(&mut rng) } - /// Sample multiple shots and return as arrays suitable for decoding. - /// - /// This is the main method for threshold estimation. Returns detection - /// events and observable flips in the same format as Stim's DEM sampler. + /// Sample multiple shots. /// /// Args: /// `num_shots`: Number of shots to sample. + /// seed: Optional random seed for reproducibility. /// /// Returns: - /// Tuple of (`detection_events`, `observable_flips`) where: - /// - `detection_events`: List of lists, each inner list contains bool per detector - /// - `observable_flips`: List of lists, each inner list contains bool per observable - fn sample_batch(&mut self, num_shots: usize) -> (Vec>, Vec>) { - use pecos_qec::fault_tolerance::noisy_sampler::{NoisySampler, PerLocationNoiseModel}; - - let noise_model = PerLocationNoiseModel::new(self.per_location_probs.clone()); - let mut sampler = NoisySampler::new(&self.influence_map, noise_model, self.seed); - let num_detectors = self.influence_map.detectors.len(); - let num_logicals = self - .influence_map - .influences - .max_logical_index() - .map_or(1, |i| i + 1); - - let mut all_det_events = Vec::with_capacity(num_shots); - let mut all_obs_flips = Vec::with_capacity(num_shots); + /// Tuple of (`all_detection_events`, `all_dem_output_flips`). + #[pyo3(signature = (num_shots, seed=None))] + fn sample_batch( + &self, + num_shots: usize, + seed: Option, + ) -> (Vec>, Vec>) { + use pecos_random::PecosRng; + use rand::RngExt; - for _ in 0..num_shots { - let result = sampler.sample_one(); + let mut rng = match seed { + Some(s) => PecosRng::seed_from_u64(s), + None => PecosRng::seed_from_u64(rand::rng().random()), + }; - // Convert sparse detector flips to dense bool array - let mut det_events = vec![false; num_detectors]; - for &idx in &result.detector_flips { - if (idx as usize) < num_detectors { - det_events[idx as usize] = true; - } - } + self.inner.sample_batch(num_shots, &mut rng) + } - // Convert sparse logical flips to dense bool array - let mut obs_flips = vec![false; num_logicals]; - for &idx in &result.logical_flips { - if (idx as usize) < num_logicals { - obs_flips[idx as usize] = true; - } - } + /// Generate samples and store them in Rust memory as a `SampleBatch`. + /// + /// The batch can then be decoded by multiple decoders without re-sampling. + /// This is the proper way to compare decoders: same samples, different decoders. + /// + /// Args: + /// `num_shots`: Number of shots to sample. + /// seed: Optional random seed for reproducibility. + /// + /// Returns: + /// `SampleBatch` object with samples held in Rust memory. + #[pyo3(signature = (num_shots, seed=None))] + fn generate_samples(&self, num_shots: usize, seed: Option) -> PySampleBatch { + use pecos_random::PecosRng; + use rand::RngExt; - all_det_events.push(det_events); - all_obs_flips.push(obs_flips); - } + let mut rng = match seed { + Some(s) => PecosRng::seed_from_u64(s), + None => PecosRng::seed_from_u64(rand::rng().random()), + }; - // Update seed for reproducibility of subsequent calls - self.seed = self.seed.wrapping_add(num_shots as u64); + // Use geometric columnar sampler via DemSampler. + let (det_columns, obs_columns) = self.inner.sample_batch_geometric(num_shots, &mut rng); - (all_det_events, all_obs_flips) + PySampleBatch::from_columnar(det_columns, obs_columns, num_shots) } - /// Sample and compute statistics directly in Rust. + /// Compute statistics without storing individual shots. /// - /// This is more efficient than sampling and processing in Python - /// when you only need aggregate statistics. + /// This is the most efficient method for threshold estimation when you + /// only need aggregate statistics (logical error rate, syndrome rate). /// /// Args: /// `num_shots`: Number of shots to sample. + /// seed: Optional random seed for reproducibility. /// /// Returns: /// Dictionary with statistics: /// - `total_shots`: Number of shots - /// - `logical_error_count`: Shots with logical errors + /// - `logical_error_count`: Shots with selected observable flips /// - `syndrome_count`: Shots with non-trivial syndrome - /// - `undetectable_count`: Shots with undetectable logical errors - /// - `logical_error_rate`: Fraction with logical errors + /// - `undetectable_count`: Shots with observable flips and no syndrome + /// - `logical_error_rate`: Fraction with selected observable flips /// - `syndrome_rate`: Fraction with syndromes + /// - `undetectable_rate`: Fraction with undetectable errors + #[pyo3(signature = (num_shots, seed=None))] fn sample_statistics( - &mut self, + &self, num_shots: usize, + seed: Option, py: Python<'_>, ) -> PyResult> { - use pecos_qec::fault_tolerance::noisy_sampler::{NoisySampler, PerLocationNoiseModel}; - - let noise_model = PerLocationNoiseModel::new(self.per_location_probs.clone()); - let mut sampler = NoisySampler::new(&self.influence_map, noise_model, self.seed); - let stats = sampler.sample_statistics(num_shots); + use rand::RngExt; - // Update seed - self.seed = self.seed.wrapping_add(num_shots as u64); + let actual_seed = seed.unwrap_or_else(|| rand::rng().random()); + let stats = self.inner.sample_statistics(num_shots, actual_seed); + let observable_indices = self.inner.observable_dem_output_indices(); + let tracked_op_indices = self.inner.tracked_operator_dem_output_indices(); + let per_observable = stats.observable_counts(&observable_indices); + let per_tracked_op: Vec = tracked_op_indices + .iter() + .filter_map(|&idx| stats.dem_output_counts().get(idx).copied()) + .collect(); + let logical_rates = stats.logical_rates(&observable_indices); + let n = stats.total_shots as f64; + let tracked_op_rates: Vec = per_tracked_op + .iter() + .map(|&count| count as f64 / n) + .collect(); let dict = pyo3::types::PyDict::new(py); dict.set_item("total_shots", stats.total_shots)?; @@ -1461,475 +3438,171 @@ impl PyNoisySampler { dict.set_item("logical_error_rate", stats.logical_error_rate())?; dict.set_item("syndrome_rate", stats.syndrome_rate())?; dict.set_item("undetectable_rate", stats.undetectable_rate())?; - dict.set_item("average_faults", stats.average_faults())?; + dict.set_item("per_detector", &stats.per_detector)?; + dict.set_item("per_observable", per_observable)?; + dict.set_item("per_tracked_op", per_tracked_op)?; + dict.set_item("per_dem_output", stats.dem_output_counts())?; + dict.set_item("detector_rates", stats.detector_rates())?; + dict.set_item("logical_rates", logical_rates)?; + dict.set_item("tracked_op_rates", tracked_op_rates)?; + dict.set_item("dem_output_rates", stats.dem_output_rates())?; Ok(dict.unbind()) } - /// Number of fault locations. - #[getter] - fn num_locations(&self) -> usize { - self.influence_map.locations.len() - } - - /// Number of detectors. - #[getter] - fn num_detectors(&self) -> usize { - self.influence_map.detectors.len() - } - - /// Number of logical observables. - #[getter] - fn num_logicals(&self) -> usize { - self.influence_map - .influences - .max_logical_index() - .map_or(1, |i| i + 1) + /// Get labels for the sampler's output channels. + /// + /// Returns a dict with: + /// - `outputs`: labels for output channels (raw measurements or detectors) + /// - `dem_outputs`: labels for all DEM `L` targets + /// - `observables`: labels for observables + /// - `tracked_ops`: labels for tracked operators + /// - `dual_detectors`: labels for dual-output detector channels + fn labels(&self, py: Python<'_>) -> PyResult> { + let labels = self.inner.labels(); + let dict = pyo3::types::PyDict::new(py); + dict.set_item("outputs", &labels.outputs)?; + dict.set_item("dem_outputs", &labels.dem_output_labels)?; + dict.set_item("observables", &labels.dem_output_labels)?; + dict.set_item("tracked_ops", &labels.tracked_op_labels)?; + dict.set_item("dual_detectors", &labels.dual_detectors)?; + Ok(dict.unbind()) } - /// Sample with explicit detector and observable definitions. + /// Sample and decode in a tight Rust loop, returning only the error count. /// - /// This combines `NoisySampler`'s fast per-location sampling with explicit - /// detector/observable definitions (like MNM uses). This gives the best of - /// both worlds: fast Rust-side sampling with Stim-compatible output. + /// This is the fastest path for threshold estimation -- no per-shot data + /// crosses the Rust/Python boundary. The sampler produces detection events, + /// the decoder decodes them via the `ObservableDecoder` trait, and errors + /// are counted, all in Rust. /// /// Args: - /// `num_shots`: Number of shots to sample. - /// `detectors_json`: JSON string with detector definitions. - /// `observables_json`: JSON string with observable definitions. - /// `measurement_order`: Optional list of qubit indices in `TickCircuit` measurement - /// execution order. Required when detector definitions use `TickCircuit` - /// measurement indices but the influence map uses a different ordering. - /// measurement_order[i] is the qubit measured at `TickCircuit` index i. + /// dem: DEM string (Stim format) for the decoder. + /// `num_shots`: Number of shots to sample and decode. + /// `decoder_type`: "pymatching" or "tesseract". + /// seed: Optional random seed for reproducibility. /// /// Returns: - /// Tuple of (`detection_events`, `observable_flips`) matching Stim's format. - #[pyo3(signature = (num_shots, detectors_json, observables_json, measurement_order=None))] - fn sample_with_definitions( - &mut self, + /// Number of logical errors (mismatches between decoder prediction and true flip). + #[pyo3(signature = (dem, num_shots, decoder_type="pymatching", seed=None))] + fn sample_decode_count( + &self, + dem: &str, num_shots: usize, - detectors_json: &str, - observables_json: &str, - measurement_order: Option>, - ) -> PyResult { - use pecos_qec::fault_tolerance::noisy_sampler::{NoisySampler, PerLocationNoiseModel}; - use std::collections::HashMap; - - let detector_records = parse_detector_records(detectors_json)?; - let observable_records = parse_observable_records(observables_json)?; - - let noise_model = PerLocationNoiseModel::new(self.per_location_probs.clone()); - let mut sampler = NoisySampler::new(&self.influence_map, noise_model, self.seed); - let num_im_measurements = self.influence_map.detectors.len(); - - // Build mapping from influence map indices to TickCircuit indices if measurement_order provided - let im_to_tc: Option> = measurement_order.as_ref().map(|tc_order| { - // Build (qubit, occurrence) -> TC index mapping - let mut qubit_occurrences: HashMap> = HashMap::new(); - for (tc_idx, &qubit) in tc_order.iter().enumerate() { - qubit_occurrences.entry(qubit).or_default().push(tc_idx); - } - - // Track how many times we've seen each qubit in the IM - let mut qubit_seen_count: HashMap = HashMap::new(); - - // For each IM measurement, find corresponding TC index - self.influence_map - .measurements - .iter() - .map(|&(_node, qubit, _basis)| { - let occurrence = *qubit_seen_count.entry(qubit).or_insert(0); - qubit_seen_count.insert(qubit, occurrence + 1); - - // Get the TC index for this qubit's nth occurrence - qubit_occurrences - .get(&qubit) - .and_then(|indices| indices.get(occurrence).copied()) - .unwrap_or(usize::MAX) - }) - .collect() - }); + decoder_type: &str, + seed: Option, + ) -> PyResult { + use pecos_random::PecosRng; + use rand::RngExt; - let num_tc_measurements = measurement_order - .as_ref() - .map_or(num_im_measurements, std::vec::Vec::len); + let actual_seed = seed.unwrap_or_else(|| rand::rng().random()); + let mut rng = PecosRng::seed_from_u64(actual_seed); - let mut all_det_events = Vec::with_capacity(num_shots); - let mut all_obs_flips = Vec::with_capacity(num_shots); + let mut decoder = create_observable_decoder(dem, decoder_type)?; + let observable_mask = self.inner.observable_dem_output_mask(); + // Tight sample+decode loop -- no Python involvement. + // Single-threaded: sample and decode sequentially. + let mut errors = 0usize; for _ in 0..num_shots { - let result = sampler.sample_one(); - - // Convert sparse IM measurement flips to dense TC measurement array - let mut meas_outcomes = vec![false; num_tc_measurements]; - - if let Some(ref mapping) = im_to_tc { - // Reorder from IM order to TC order - for &im_idx in &result.detector_flips { - let im_idx = im_idx as usize; - if im_idx < mapping.len() { - let tc_idx = mapping[im_idx]; - if tc_idx < num_tc_measurements { - meas_outcomes[tc_idx] = !meas_outcomes[tc_idx]; - } - } - } - } else { - // No reordering needed - for &idx in &result.detector_flips { - if (idx as usize) < num_tc_measurements { - meas_outcomes[idx as usize] = true; - } - } + let (det_events, obs_flips) = self.inner.sample(&mut rng); + let syndrome: Vec = det_events.iter().map(|&b| u8::from(b)).collect(); + let predicted_mask = decoder.decode_to_observables(&syndrome).unwrap_or(u64::MAX); + let true_mask = self.inner.observable_mask_from_dem_output_flips(&obs_flips); + if (predicted_mask & observable_mask) != true_mask { + errors += 1; } + } + Ok(errors) + } - // Apply detector definitions (XOR of measurement outcomes) - let det_events: Vec = detector_records - .iter() - .map(|records| { - let mut fired = false; - for &offset in records { - #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] // measurement count fits in i32 - #[allow(clippy::cast_sign_loss)] - // negative offset + total count, or non-negative offset - let abs_idx = if offset < 0 { - (num_tc_measurements as i32 + offset) as usize - } else { - offset as usize - }; - if abs_idx < num_tc_measurements && meas_outcomes[abs_idx] { - fired = !fired; + /// Parallel sample+decode: distributes shots across threads. + /// + /// Each thread gets its own sampler clone and decoder instance. + /// Much faster for slow decoders (Tesseract) where decode time dominates. + /// + /// Args: + /// dem: DEM string (Stim format) for the decoder. + /// `num_shots`: Number of shots to sample and decode. + /// `decoder_type`: "pymatching", "tesseract", "`bp_osd`", "`bp_lsd`", or "`union_find`". + /// seed: Optional base random seed. Each thread gets seed + `thread_id`. + /// `num_workers`: Number of parallel workers (default: number of CPUs). + /// + /// Returns: + /// Number of logical errors. + #[pyo3(signature = (dem, num_shots, decoder_type="pymatching", seed=None, num_workers=None))] + fn sample_decode_count_parallel( + &self, + dem: &str, + num_shots: usize, + decoder_type: &str, + seed: Option, + num_workers: Option, + ) -> PyResult { + use rayon::prelude::*; + + let actual_seed = seed.unwrap_or(0); + let n_workers = num_workers.unwrap_or_else(rayon::current_num_threads); + + // Validate decoder type early + create_observable_decoder(dem, decoder_type)?; + + let pool = rayon::ThreadPoolBuilder::new() + .num_threads(n_workers) + .build() + .map_err(|e| PyErr::new::(e.to_string()))?; + + let shots_per_worker = num_shots / n_workers; + let remainder = num_shots % n_workers; + + let sampler = &self.inner; + let observable_mask = sampler.observable_dem_output_mask(); + let dem_str = dem.to_string(); + let dt = decoder_type.to_string(); + + let total_errors: usize = pool.install(|| { + (0..n_workers) + .into_par_iter() + .map(|worker_id| { + use pecos_random::PecosRng; + + let my_shots = shots_per_worker + usize::from(worker_id < remainder); + if my_shots == 0 { + return 0; + } + + let my_sampler = sampler.clone(); + let mut my_rng = + PecosRng::seed_from_u64(actual_seed.wrapping_add(worker_id as u64)); + // unwrap is safe: we validated above + let mut decoder = create_observable_decoder(&dem_str, &dt).unwrap(); + + let mut errors = 0usize; + for _ in 0..my_shots { + let (det_events, obs_flips) = my_sampler.sample(&mut my_rng); + let syndrome: Vec = det_events.iter().map(|&b| u8::from(b)).collect(); + let predicted = + decoder.decode_to_observables(&syndrome).unwrap_or(u64::MAX); + let truth = my_sampler.observable_mask_from_dem_output_flips(&obs_flips); + if (predicted & observable_mask) != truth { + errors += 1; } } - fired + errors }) - .collect(); + .sum() + }); - // Apply observable definitions - let obs_flips: Vec = observable_records - .iter() - .map(|records| { - let mut flipped = false; - for &offset in records { - #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] // measurement count fits in i32 - #[allow(clippy::cast_sign_loss)] - // negative offset + total count, or non-negative offset - let abs_idx = if offset < 0 { - (num_tc_measurements as i32 + offset) as usize - } else { - offset as usize - }; - if abs_idx < num_tc_measurements && meas_outcomes[abs_idx] { - flipped = !flipped; - } - } - flipped - }) - .collect(); - - all_det_events.push(det_events); - all_obs_flips.push(obs_flips); - } - - self.seed = self.seed.wrapping_add(num_shots as u64); - Ok((all_det_events, all_obs_flips)) - } - - fn __repr__(&self) -> String { - format!( - "NoisySampler(locations={}, detectors={}, logicals={})", - self.num_locations(), - self.num_detectors(), - self.num_logicals(), - ) - } -} - -// --- MNM Builder --- - -/// Builder for Measurement Noise Models (MNMs). -/// -/// Constructs a MNM from a fault influence map. The MNM aggregates fault locations -/// by their measurement effects (which measurements flip), enabling fast approximate -/// sampling. -/// -/// # Comparison with DEM -/// -/// | Aspect | DEM | MNM | -/// |--------|-----|-----| -/// | Maps to | Detectors | Measurements | -/// | Use case | Decoding | Sampling | -/// | Aggregates by | Detector signature | Measurement signature | -/// | Output | Stim-compatible DEM | Raw measurement outcomes | -/// -/// # Example -/// -/// ```python -/// from pecos_rslib.qec import DagFaultAnalyzer, MemBuilder -/// -/// # Build influence map -/// analyzer = DagFaultAnalyzer(dag) -/// influence_map = analyzer.build_influence_map() -/// -/// # Build MNM for fast sampling -/// mnm = MemBuilder(influence_map).with_noise(0.01, 0.01, 0.01, 0.01).build() -/// -/// # Sample many shots quickly -/// for _ in range(10000): -/// outcomes = mnm.sample() -/// ``` -#[pyclass(name = "MemBuilder", module = "pecos_rslib.qec")] -pub struct PyMemBuilder { - influence_map: RustDagFaultInfluenceMap, - p1: f64, - p2: f64, - p_meas: f64, - p_init: f64, - /// Measurement order from original circuit (list of qubits in measurement order). - measurement_order: Option>, -} - -#[pymethods] -impl PyMemBuilder { - /// Create a new MNM builder from a fault influence map. - /// - /// Args: - /// `influence_map`: A `DagFaultInfluenceMap` from `DagFaultAnalyzer`. - #[new] - fn new(influence_map: &PyDagFaultInfluenceMap) -> Self { - Self { - influence_map: influence_map.inner.clone(), - p1: 0.01, - p2: 0.01, - p_meas: 0.01, - p_init: 0.01, - measurement_order: None, - } - } - - /// Set the noise parameters. - /// - /// Args: - /// p1: Single-qubit depolarizing error rate. - /// p2: Two-qubit depolarizing error rate. - /// `p_meas`: Measurement error rate. - /// `p_init`: Initialization (prep) error rate. - /// - /// Returns: - /// Self for method chaining. - fn with_noise( - mut slf: PyRefMut<'_, Self>, - p1: f64, - p2: f64, - p_meas: f64, - p_init: f64, - ) -> PyRefMut<'_, Self> { - slf.p1 = p1; - slf.p2 = p2; - slf.p_meas = p_meas; - slf.p_init = p_init; - slf - } - - /// Set the measurement order from the original circuit (e.g., `TickCircuit`). - /// - /// This is needed when detector definitions use `TickCircuit` measurement indices - /// but the influence map uses a different ordering based on DAG topology. - /// - /// Args: - /// order: List of qubit indices in measurement execution order. - /// order[i] is the qubit measured at `TickCircuit` measurement index i. - /// - /// Returns: - /// Self for method chaining. - fn with_measurement_order( - mut slf: PyRefMut<'_, Self>, - order: Vec, - ) -> PyRefMut<'_, Self> { - slf.measurement_order = Some(order); - slf - } - - /// Build the Measurement Noise Model. - /// - /// This aggregates all fault locations by their measurement effects. - /// Locations that produce the same measurement signature have their - /// probabilities combined using the independent error formula. - /// - /// Returns: - /// A `MeasurementNoiseModel` for fast approximate sampling. - fn build(&self) -> PyMeasurementNoiseModel { - let mut builder = RustMemBuilder::new(&self.influence_map).with_noise( - self.p1, - self.p2, - self.p_meas, - self.p_init, - ); - - if let Some(ref order) = self.measurement_order { - builder = builder.with_measurement_order(order.clone()); - } - - let inner = builder.build(); - PyMeasurementNoiseModel { inner } - } - - fn __repr__(&self) -> String { - format!( - "MemBuilder(p1={}, p2={}, p_meas={}, p_init={})", - self.p1, self.p2, self.p_meas, self.p_init - ) - } -} - -// --- DEM Sampler (Fast DEM-style sampling) --- - -/// Fast DEM-style sampler for threshold estimation. -/// -/// This sampler aggregates fault effects directly into detector/observable signatures, -/// matching Stim's DEM sampler semantics. It uses data-oriented design for optimal -/// cache performance: -/// -/// - Precomputed u64 thresholds (no f64 comparison during sampling) -/// - CSR layout for detector/observable indices -/// - Bit-packed outcomes for compact storage and fast XOR -/// -/// # Example -/// -/// ```python -/// from pecos_rslib.qec import DagFaultAnalyzer, DemSamplerBuilder -/// -/// # Build influence map -/// analyzer = DagFaultAnalyzer(dag) -/// influence_map = analyzer.build_influence_map() -/// -/// # Build sampler with explicit detector/observable definitions -/// sampler = DemSamplerBuilder(influence_map) \ -/// .with_noise(0.01, 0.01, 0.01, 0.01) \ -/// .with_detectors_json(detectors_json) \ -/// .with_observables_json(observables_json) \ -/// .with_measurement_order(measurement_order) \ -/// .build() -/// -/// # Fast batch sampling for threshold estimation -/// det_events, obs_flips = sampler.sample_batch(10000) -/// ``` -#[pyclass(name = "DemSampler", module = "pecos_rslib.qec")] -pub struct PyDemSampler { - inner: pecos_qec::fault_tolerance::dem_builder::DemSampler, -} - -#[pymethods] -impl PyDemSampler { - /// Number of mechanisms in the sampler. - #[getter] - fn num_mechanisms(&self) -> usize { - self.inner.num_mechanisms() - } - - /// Number of detectors. - #[getter] - fn num_detectors(&self) -> usize { - self.inner.num_detectors() - } - - /// Number of observables. - #[getter] - fn num_observables(&self) -> usize { - self.inner.num_observables() - } - - /// Sample a single shot. - /// - /// Args: - /// seed: Optional random seed for reproducibility. - /// - /// Returns: - /// Tuple of (`detection_events`, `observable_flips`) as boolean lists. - #[pyo3(signature = (seed=None))] - fn sample(&self, seed: Option) -> (Vec, Vec) { - use pecos_random::PecosRng; - use rand::RngExt; - - let mut rng = match seed { - Some(s) => PecosRng::seed_from_u64(s), - None => PecosRng::seed_from_u64(rand::rng().random()), - }; - - self.inner.sample(&mut rng) - } - - /// Sample multiple shots. - /// - /// Args: - /// `num_shots`: Number of shots to sample. - /// seed: Optional random seed for reproducibility. - /// - /// Returns: - /// Tuple of (`all_detection_events`, `all_observable_flips`). - #[pyo3(signature = (num_shots, seed=None))] - fn sample_batch( - &self, - num_shots: usize, - seed: Option, - ) -> (Vec>, Vec>) { - use pecos_random::PecosRng; - use rand::RngExt; - - let mut rng = match seed { - Some(s) => PecosRng::seed_from_u64(s), - None => PecosRng::seed_from_u64(rand::rng().random()), - }; - - self.inner.sample_batch(num_shots, &mut rng) - } - - /// Compute statistics without storing individual shots. - /// - /// This is the most efficient method for threshold estimation when you - /// only need aggregate statistics (logical error rate, syndrome rate). - /// - /// Args: - /// `num_shots`: Number of shots to sample. - /// seed: Optional random seed for reproducibility. - /// - /// Returns: - /// Dictionary with statistics: - /// - `total_shots`: Number of shots - /// - `logical_error_count`: Shots with logical errors - /// - `syndrome_count`: Shots with non-trivial syndrome - /// - `undetectable_count`: Shots with undetectable logical errors - /// - `logical_error_rate`: Fraction with logical errors - /// - `syndrome_rate`: Fraction with syndromes - /// - `undetectable_rate`: Fraction with undetectable errors - #[pyo3(signature = (num_shots, seed=None))] - fn sample_statistics( - &self, - num_shots: usize, - seed: Option, - py: Python<'_>, - ) -> PyResult> { - use rand::RngExt; - - let actual_seed = seed.unwrap_or_else(|| rand::rng().random()); - let stats = self.inner.sample_statistics(num_shots, actual_seed); - - let dict = pyo3::types::PyDict::new(py); - dict.set_item("total_shots", stats.total_shots)?; - dict.set_item("logical_error_count", stats.logical_error_count)?; - dict.set_item("syndrome_count", stats.syndrome_count)?; - dict.set_item("undetectable_count", stats.undetectable_count)?; - dict.set_item("logical_error_rate", stats.logical_error_rate())?; - dict.set_item("syndrome_rate", stats.syndrome_rate())?; - dict.set_item("undetectable_rate", stats.undetectable_rate())?; - Ok(dict.unbind()) + Ok(total_errors) } fn __repr__(&self) -> String { format!( - "DemSampler(mechanisms={}, detectors={}, observables={})", + "DemSampler(mechanisms={}, outputs={}, dem_outputs={}, observables={}, tracked_ops={})", self.num_mechanisms(), - self.num_detectors(), + self.num_outputs(), + self.num_dem_outputs(), self.num_observables(), + self.num_tracked_ops(), ) } } @@ -1937,14 +3610,11 @@ impl PyDemSampler { /// Builder for `DemSampler`. /// /// Constructs a `DemSampler` from a fault influence map, noise parameters, -/// and explicit detector/observable definitions. +/// and explicit detector / observable definitions. #[pyclass(name = "DemSamplerBuilder", module = "pecos_rslib.qec")] pub struct PyDemSamplerBuilder { influence_map: RustDagFaultInfluenceMap, - p1: f64, - p2: f64, - p_meas: f64, - p_init: f64, + noise: NoiseConfig, detectors_json: Option, observables_json: Option, measurement_order: Option>, @@ -1957,10 +3627,7 @@ impl PyDemSamplerBuilder { fn new(influence_map: &PyDagFaultInfluenceMap) -> Self { Self { influence_map: influence_map.inner.clone(), - p1: 0.01, - p2: 0.01, - p_meas: 0.01, - p_init: 0.01, + noise: NoiseConfig::default(), detectors_json: None, observables_json: None, measurement_order: None, @@ -1968,27 +3635,44 @@ impl PyDemSamplerBuilder { } /// Set noise parameters. + #[pyo3(signature = (p1, p2, p_meas, p_prep, p_idle=None, t1=None, t2=None, idle_rz=None))] + #[allow(clippy::too_many_arguments)] fn with_noise( mut slf: PyRefMut<'_, Self>, p1: f64, p2: f64, p_meas: f64, - p_init: f64, + p_prep: f64, + p_idle: Option, + t1: Option, + t2: Option, + idle_rz: Option, ) -> PyRefMut<'_, Self> { - slf.p1 = p1; - slf.p2 = p2; - slf.p_meas = p_meas; - slf.p_init = p_init; + let mut noise = NoiseConfig::new(p1, p2, p_meas, p_prep); + noise.p_idle = p_idle.unwrap_or(0.0); + if let (Some(t1_val), Some(t2_val)) = (t1, t2) { + noise = noise.set_t1_t2(t1_val, t2_val); + } + if let Some(rz) = idle_rz { + noise = noise.set_idle_rz(rz); + } + slf.noise = noise; slf } /// Set detector definitions from JSON. + /// + /// Accepts either legacy detector rows with an `"id"` key or public surface + /// descriptor rows with a `"detector_id"` key. fn with_detectors_json(mut slf: PyRefMut<'_, Self>, json: String) -> PyRefMut<'_, Self> { slf.detectors_json = Some(json); slf } /// Set observable definitions from JSON. + /// + /// Tracked operators are carried by the influence map; this helper is for + /// observable metadata. fn with_observables_json(mut slf: PyRefMut<'_, Self>, json: String) -> PyRefMut<'_, Self> { slf.observables_json = Some(json); slf @@ -2005,14 +3689,8 @@ impl PyDemSamplerBuilder { /// Build the `DemSampler`. fn build(&self) -> PyResult { - use pecos_qec::fault_tolerance::dem_builder::DemSamplerBuilder; - - let mut builder = DemSamplerBuilder::new(&self.influence_map).with_noise( - self.p1, - self.p2, - self.p_meas, - self.p_init, - ); + let mut builder = RustNewDemSamplerBuilder::new(&self.influence_map) + .with_noise_config(self.noise.clone()); if let Some(ref json) = self.detectors_json { builder = builder @@ -2030,19 +3708,23 @@ impl PyDemSamplerBuilder { builder = builder.with_measurement_order(order.clone()); } - let inner = builder.build(); + let inner = builder + .build() + .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))?; Ok(PyDemSampler { inner }) } fn __repr__(&self) -> String { format!( - "DemSamplerBuilder(p1={}, p2={}, p_meas={}, p_init={})", - self.p1, self.p2, self.p_meas, self.p_init + "DemSamplerBuilder(p1={}, p2={}, p_meas={}, p_prep={}, p_idle={:?})", + self.noise.p1, self.noise.p2, self.noise.p_meas, self.noise.p_prep, self.noise.p_idle ) } } -// --- DEM Equivalence Validation --- +// ============================================================================= +// DEM Equivalence Validation +// ============================================================================= /// Result of DEM equivalence comparison. /// @@ -2220,10 +3902,36 @@ impl PyParsedDem { self.inner.num_detectors } - /// Number of observables (max ID + 1). + /// Number of observables. #[getter] fn num_observables(&self) -> u32 { - self.inner.num_observables + self.inner.num_observables() + } + + /// Total number of outputs in the DEM `L` namespace. + #[getter] + fn num_dem_outputs(&self) -> u32 { + self.inner.num_dem_outputs() + } + + /// Number of tracked operators. + #[getter] + fn num_tracked_ops(&self) -> u32 { + self.inner.num_tracked_ops() + } + + /// Convert to a decomposed (graphlike) DEM string. + /// + /// Mechanisms with <= 2 detectors pass through unchanged. + /// Hyperedges (3+ detectors) cannot be decomposed without Pauli + /// provenance and will raise an error. + /// + /// For proper decomposition, use ``coherent_dem_decomposed()`` + /// or ``noise_characterization()`` which track X/Z components. + fn to_string_decomposed(&self) -> PyResult { + self.inner + .to_string_decomposed() + .map_err(|e| pyo3::exceptions::PyValueError::new_err(e)) } /// Aggregate mechanisms by their effect. @@ -2246,264 +3954,1566 @@ impl PyParsedDem { dict.set_item(key_tuple, prob)?; } - Ok(dict.unbind()) - } - - /// Sample from this DEM. - /// - /// Args: - /// seed: Optional random seed for reproducibility. - /// - /// Returns: - /// Tuple of (`detector_events`, `observable_flips`) as boolean lists. - #[pyo3(signature = (seed=None))] - fn sample(&self, seed: Option) -> (Vec, Vec) { - use pecos_random::PecosRng; - use rand::RngExt; + Ok(dict.unbind()) + } + + /// Sample from this DEM. + /// + /// Args: + /// seed: Optional random seed for reproducibility. + /// + /// Returns: + /// Tuple of (`detector_events`, `dem_output_flips`) as boolean lists. + #[pyo3(signature = (seed=None))] + fn sample(&self, seed: Option) -> (Vec, Vec) { + use pecos_random::PecosRng; + use rand::RngExt; + + let mut rng = match seed { + Some(s) => PecosRng::seed_from_u64(s), + None => PecosRng::seed_from_u64(rand::rng().random()), + }; + + self.inner.sample(&mut rng) + } + + /// Sample multiple shots from this DEM. + /// + /// Args: + /// `num_shots`: Number of shots to sample. + /// seed: Optional random seed for reproducibility. + /// + /// Returns: + /// Tuple of (`all_detector_events`, `all_dem_output_flips`). + #[pyo3(signature = (num_shots, seed=None))] + fn sample_batch( + &self, + num_shots: usize, + seed: Option, + ) -> (Vec>, Vec>) { + use pecos_random::PecosRng; + use rand::RngExt; + + let mut rng = match seed { + Some(s) => PecosRng::seed_from_u64(s), + None => PecosRng::seed_from_u64(rand::rng().random()), + }; + + self.inner.sample_batch(num_shots, &mut rng) + } + + /// Convert to an optimized `DemSampler` for fast batch sampling. + /// + /// The `DemSampler` uses geometric skip sampling and parallel chunked + /// processing, which is significantly faster than `sample_batch` for + /// large shot counts and low error rates. + /// + /// Returns: + /// `DemSampler`: Optimized sampler for this DEM. + /// + /// Example: + /// >>> dem = `ParsedDem.from_string("error(0.01)` D0 D1") + /// >>> sampler = `dem.to_dem_sampler()` + /// >>> stats = `sampler.sample_statistics(100000`, seed=42) + fn to_dem_sampler(&self) -> PyDemSampler { + PyDemSampler { + inner: self.inner.to_dem_sampler(), + } + } + + fn __repr__(&self) -> String { + format!( + "ParsedDem(mechanisms={}, detectors={}, dem_outputs={}, observables={}, tracked_ops={})", + self.inner.mechanisms.len(), + self.inner.num_detectors, + self.inner.num_dem_outputs(), + self.inner.num_observables(), + self.inner.num_tracked_ops() + ) + } +} + +/// Compare two DEMs for exact mechanism match. +/// +/// This comparison aggregates mechanisms by effect and compares probabilities. +/// Appropriate for non-decomposed DEMs or when exact match is required. +/// +/// Args: +/// dem1: First DEM string or `ParsedDem`. +/// dem2: Second DEM string or `ParsedDem`. +/// `prob_tolerance`: Relative tolerance for probability comparison (default 1e-6). +/// +/// Returns: +/// `EquivalenceResult` with comparison statistics. +/// +/// Example: +/// >>> result = `compare_dems_exact(dem1_str`, `dem2_str`, `prob_tolerance=0.001`) +/// >>> if result.equivalent: +/// ... print("DEMs are equivalent") +#[pyfunction] +#[pyo3(signature = (dem1, dem2, prob_tolerance=1e-6))] +fn compare_dems_exact( + dem1: &str, + dem2: &str, + prob_tolerance: f64, +) -> PyResult { + let parsed1 = dem1 + .parse::() + .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("DEM1 parse error: {e}")))?; + let parsed2 = dem2 + .parse::() + .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("DEM2 parse error: {e}")))?; + + let inner = rust_compare_dems_exact(&parsed1, &parsed2, prob_tolerance); + Ok(PyEquivalenceResult { inner }) +} + +/// Compare two DEMs statistically by sampling. +/// +/// This is the most robust comparison method as it accounts for all +/// decomposition strategies and probability combinations. It compares +/// the joint distribution of syndrome patterns, not just marginal rates. +/// +/// Args: +/// dem1: First DEM string or `ParsedDem`. +/// dem2: Second DEM string or `ParsedDem`. +/// `num_shots`: Number of shots for sampling (default 100,000). +/// seed: Random seed (default 42). +/// tolerance: Maximum relative difference to consider equivalent (default 0.05). +/// +/// Returns: +/// `EquivalenceResult` with comparison statistics. +/// +/// Example: +/// >>> result = `compare_dems_statistical(dem1_str`, `dem2_str`, `num_shots=50000`) +/// >>> print(f"Correlation: {result.correlation}") +#[pyfunction] +#[pyo3(signature = (dem1, dem2, num_shots=100_000, seed=42, tolerance=0.05))] +fn compare_dems_statistical( + dem1: &str, + dem2: &str, + num_shots: usize, + seed: u64, + tolerance: f64, +) -> PyResult { + let parsed1 = dem1 + .parse::() + .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("DEM1 parse error: {e}")))?; + let parsed2 = dem2 + .parse::() + .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("DEM2 parse error: {e}")))?; + + let inner = rust_compare_dems_statistical(&parsed1, &parsed2, num_shots, seed, tolerance); + Ok(PyEquivalenceResult { inner }) +} + +/// Convenience function to verify DEM equivalence. +/// +/// Args: +/// dem1: First DEM string. +/// dem2: Second DEM string. +/// method: Comparison method - "exact" or "statistical" (default "exact"). +/// `prob_tolerance`: For exact: probability tolerance (default 1e-6). +/// `num_shots`: For statistical: number of shots (default 100,000). +/// tolerance: For statistical: rate tolerance (default 0.05). +/// seed: For statistical: random seed (default 42). +/// +/// Returns: +/// True if DEMs are equivalent within tolerance. +/// +/// Example: +/// >>> if `verify_dem_equivalence(dem1`, dem2, method="exact"): +/// ... print("DEMs match exactly") +#[pyfunction] +#[pyo3(signature = (dem1, dem2, method="exact", prob_tolerance=1e-6, num_shots=100_000, tolerance=0.05, seed=42))] +fn verify_dem_equivalence( + dem1: &str, + dem2: &str, + method: &str, + prob_tolerance: f64, + num_shots: usize, + tolerance: f64, + seed: u64, +) -> PyResult { + let comparison_method = match method { + "exact" => RustComparisonMethod::Exact { prob_tolerance }, + "statistical" => RustComparisonMethod::Statistical { + num_shots, + seed, + tolerance, + }, + _ => { + return Err(pyo3::exceptions::PyValueError::new_err( + "method must be 'exact' or 'statistical'", + )); + } + }; + + rust_verify_dem_equivalence(dem1, dem2, &comparison_method) + .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string())) +} + +/// Assert that two DEMs are equivalent, raising an error if not. +/// +/// This is a convenience function for testing that raises `AssertionError` +/// if the DEMs are not equivalent. +/// +/// Args: +/// dem1: First DEM string. +/// dem2: Second DEM string. +/// method: Comparison method - "exact" or "statistical" (default "exact"). +/// `prob_tolerance`: For exact: probability tolerance (default 1e-6). +/// `num_shots`: For statistical: number of shots (default 100,000). +/// tolerance: For statistical: rate tolerance (default 0.05). +/// seed: For statistical: random seed (default 42). +/// +/// Raises: +/// `AssertionError`: If DEMs are not equivalent. +/// +/// Example: +/// >>> `assert_dems_equivalent(dem1`, dem2, method="exact") # Raises if not equivalent +#[pyfunction] +#[pyo3(signature = (dem1, dem2, method="exact", prob_tolerance=1e-6, num_shots=100_000, tolerance=0.05, seed=42))] +fn assert_dems_equivalent( + dem1: &str, + dem2: &str, + method: &str, + prob_tolerance: f64, + num_shots: usize, + tolerance: f64, + seed: u64, +) -> PyResult<()> { + let parsed1 = dem1 + .parse::() + .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("DEM1 parse error: {e}")))?; + let parsed2 = dem2 + .parse::() + .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("DEM2 parse error: {e}")))?; + + let result = match method { + "exact" => rust_compare_dems_exact(&parsed1, &parsed2, prob_tolerance), + "statistical" => { + rust_compare_dems_statistical(&parsed1, &parsed2, num_shots, seed, tolerance) + } + _ => { + return Err(pyo3::exceptions::PyValueError::new_err( + "method must be 'exact' or 'statistical'", + )); + } + }; + + if result.equivalent { + Ok(()) + } else { + let msg = format!( + "DEMs are not equivalent: max_rate_diff={:.6}, only_in_dem1={:?}, only_in_dem2={:?}", + result.max_rate_difference, result.details.only_in_dem1, result.details.only_in_dem2 + ); + Err(pyo3::exceptions::PyAssertionError::new_err(msg)) + } +} + +// ============================================================================= +// CSS UF Decoder (UIUF) +// ============================================================================= + +/// CSS-aware Union-Find decoder using the UIUF algorithm. +/// +/// Takes separate X and Z DEM strings and decodes them jointly, exploiting +/// Y-error identification through cluster intersection. +/// +/// `Example::` +/// +/// decoder = CssUfDecoder(x_dem_str, z_dem_str) +/// x_obs, z_obs = decoder.decode_css(x_syndrome, z_syndrome) +/// +#[pyclass(name = "CssUfDecoder", module = "pecos_rslib.qec")] +pub struct PyCssUfDecoder { + inner: pecos_decoders::CssUfDecoder, +} + +#[pymethods] +impl PyCssUfDecoder { + /// Create a CSS UF decoder from X and Z DEM strings. + /// + /// The qubit-edge mapping is auto-detected from detector coordinates. + /// If coordinates are missing, falls back to independent X/Z decoding. + #[new] + fn new(x_dem: &str, z_dem: &str) -> PyResult { + let inner = pecos_decoders::CssUfDecoder::from_dems( + x_dem, + z_dem, + pecos_decoders::UfDecoderConfig::accurate(), + ) + .map_err(|e| PyErr::new::(e.to_string()))?; + Ok(Self { inner }) + } + + /// Decode X and Z syndromes jointly using UIUF. + /// + /// Args: + /// `x_syndrome`: X-basis detection events (bytes). + /// `z_syndrome`: Z-basis detection events (bytes). + /// + /// Returns: + /// Tuple of (`x_observable_mask`, `z_observable_mask`). + fn decode_css(&mut self, x_syndrome: &[u8], z_syndrome: &[u8]) -> PyResult<(u64, u64)> { + self.inner + .decode_css(x_syndrome, z_syndrome) + .map_err(|e| PyErr::new::(e.to_string())) + } + + /// Number of matched qubit pairs between X and Z graphs. + /// 0 means no mapping was found (falls back to independent decode). + #[getter] + fn num_qubit_pairs(&self) -> usize { + self.inner.num_qubit_pairs() + } + + /// Count erasures the intersection would produce for given syndromes. + fn count_erasures(&mut self, x_syndrome: &[u8], z_syndrome: &[u8]) -> usize { + self.inner + .count_intersection_erasures(x_syndrome, z_syndrome) + } + + /// Decode a batch of syndromes and return the error count. + /// + /// Each shot has concatenated `[x_syndrome | z_syndrome]`. + /// The `x_syndrome` length is specified by `x_num_detectors`. + /// + /// Args: + /// syndromes: List of concatenated syndrome byte arrays. + /// `true_obs_masks`: True observable masks for each shot. + /// `x_num_detectors`: Length of the X syndrome prefix. + /// + /// Returns: + /// Number of logical errors. + fn decode_count_batch( + &mut self, + syndromes: Vec>, + true_obs_masks: Vec, + x_num_detectors: usize, + ) -> PyResult { + let mut errors = 0; + for (syn, &true_obs) in syndromes.iter().zip(true_obs_masks.iter()) { + let x_syn = &syn[..x_num_detectors.min(syn.len())]; + let z_syn = &syn[x_num_detectors.min(syn.len())..]; + let (x_obs, z_obs) = self + .inner + .decode_css(x_syn, z_syn) + .map_err(|e| PyErr::new::(e.to_string()))?; + let predicted = x_obs ^ z_obs; + if predicted != true_obs { + errors += 1; + } + } + Ok(errors) + } +} + +// ============================================================================= +// Observable Subgraph Decoder (Python class) +// ============================================================================= + +/// Per-observable subgraph decoder for transversal gates. +/// +/// Partitions a DEM into per-observable graphlike subgraphs using +/// stabilizer coordinate information, then decodes each independently. +/// +/// Args: +/// dem: DEM string in Stim format with detector coordinate declarations. +/// `stab_coords`: List of dicts, one per logical qubit. Each dict has +/// keys "X" and "Z" mapping to lists of (x, y) ancilla coordinates. +/// `inner_decoder`: Inner decoder type string (default "`pecos_uf:fast`"). +/// +/// Example: +/// >>> decoder = `ObservableSubgraphDecoder`( +/// ... `dem_str`, +/// ... [{"X": [(1,0), (3,1)], "Z": [(0,3), (1,1)]}], +/// ... "`pecos_uf:fast`", +/// ... ) +/// >>> obs = decoder.decode(syndrome) +#[pyclass(name = "ObservableSubgraphDecoder", module = "pecos_rslib.qec")] +pub struct PyObservableSubgraphDecoder { + inner: pecos_decoder_core::observable_subgraph::ObservableSubgraphDecoder, +} + +#[pymethods] +impl PyObservableSubgraphDecoder { + #[new] + #[pyo3(signature = (dem, stab_coords, inner_decoder="pecos_uf:fast", max_time_radius=None))] + fn new( + dem: &str, + stab_coords: Vec>, + inner_decoder: &str, + max_time_radius: Option, + ) -> PyResult { + use pecos_decoder_core::observable_subgraph::{ObservableSubgraphDecoder, QubitStabCoords}; + + // Parse stab_coords from Python dicts + let mut rust_stab_coords = Vec::with_capacity(stab_coords.len()); + for dict in &stab_coords { + let x_list: Vec<(f64, f64)> = dict + .get_item("X")? + .ok_or_else(|| PyErr::new::("Missing 'X' key"))? + .extract()?; + let z_list: Vec<(f64, f64)> = dict + .get_item("Z")? + .ok_or_else(|| PyErr::new::("Missing 'Z' key"))? + .extract()?; + rust_stab_coords.push(QubitStabCoords { + x_positions: x_list, + z_positions: z_list, + }); + } + + // Wrapper to make any ObservableDecoder Send. + // All our decoder implementations own their data (no Rc/RefCell), + // so this is safe. The GIL prevents concurrent Python access. + struct SendWrapper(Box); + unsafe impl Send for SendWrapper {} + unsafe impl Sync for SendWrapper {} + impl pecos_decoders::ObservableDecoder for SendWrapper { + fn decode_to_observables( + &mut self, + syndrome: &[u8], + ) -> Result { + self.0.decode_to_observables(syndrome) + } + } + + let inner = ObservableSubgraphDecoder::from_dem_windowed( + dem, + &rust_stab_coords, + max_time_radius, + |subgraph| { + let sub_dem = subgraph_to_dem_string(subgraph); + let decoder = create_observable_decoder(&sub_dem, inner_decoder) + .map_err(|e| pecos_decoders::DecoderError::InternalError(e.to_string()))?; + Ok(Box::new(SendWrapper(decoder)) + as Box) + }, + ) + .map_err(|e| PyErr::new::(e.to_string()))?; + + Ok(Self { inner }) + } + + /// Decode a syndrome and return observable flip predictions. + fn decode(&mut self, syndrome: Vec) -> PyResult { + use pecos_decoder_core::ObservableDecoder; + self.inner + .decode_to_observables(&syndrome) + .map_err(|e| PyErr::new::(e.to_string())) + } + + /// Number of observables this decoder handles. + fn num_observables(&self) -> usize { + self.inner.num_observables() + } + + /// Decode a batch of syndromes and return observable predictions. + /// + /// Args: + /// syndromes: 2D numpy array of shape (`num_shots`, `num_detectors`). + /// + /// Returns: + /// List of observable flip masks (one per shot). + fn decode_batch(&mut self, syndromes: Vec>) -> PyResult> { + use pecos_decoder_core::ObservableDecoder; + let mut results = Vec::with_capacity(syndromes.len()); + for syn in &syndromes { + let obs = self + .inner + .decode_to_observables(syn) + .map_err(|e| PyErr::new::(e.to_string()))?; + results.push(obs); + } + Ok(results) + } + + /// Decode a `SampleBatch` and return the number of logical errors. + /// + /// This runs entirely in Rust — no Python per-shot overhead. + /// + /// Args: + /// batch: A `SampleBatch` from `DemSampler.generate_samples()`. + /// + /// Returns: + /// Number of logical errors. + fn decode_count(&mut self, batch: &PySampleBatch) -> PyResult { + let detection_events: Vec> = (0..batch.num_shots) + .map(|i| { + let mut s = vec![0u8; batch.num_detectors]; + batch.extract_syndrome(i, &mut s); + s + }) + .collect(); + let observable_masks: Vec = (0..batch.num_shots) + .map(|i| batch.extract_obs_mask(i)) + .collect(); + self.inner + .decode_count_batched(&detection_events, &observable_masks) + .map_err(|e| PyErr::new::(e.to_string())) + } + + /// Decode a `SampleBatch` in parallel using rayon. + /// + /// Creates per-worker decoder instances to avoid lock contention. + /// Requires the DEM string and inner decoder type for reconstruction. + #[pyo3(signature = (batch, dem, stab_coords, inner_decoder="pymatching", num_workers=None, max_time_radius=None))] + fn decode_count_parallel( + &self, + batch: &PySampleBatch, + dem: &str, + stab_coords: Vec>, + inner_decoder: &str, + num_workers: Option, + max_time_radius: Option, + ) -> PyResult { + use pecos_decoder_core::observable_subgraph::{ObservableSubgraphDecoder, QubitStabCoords}; + use rayon::prelude::*; + + // Parse stab_coords + let mut sc = Vec::with_capacity(stab_coords.len()); + for dict in &stab_coords { + let x: Vec<(f64, f64)> = dict + .get_item("X")? + .ok_or_else(|| PyErr::new::("X"))? + .extract()?; + let z: Vec<(f64, f64)> = dict + .get_item("Z")? + .ok_or_else(|| PyErr::new::("Z"))? + .extract()?; + sc.push(QubitStabCoords { + x_positions: x, + z_positions: z, + }); + } + + let dem_str = dem.to_string(); + let inner_str = inner_decoder.to_string(); + let n = batch.num_shots; + + // Materialize row-major data for parallel decode. + let events: Vec> = (0..n) + .map(|i| { + let mut s = vec![0u8; batch.num_detectors]; + batch.extract_syndrome(i, &mut s); + s + }) + .collect(); + let masks: Vec = (0..n).map(|i| batch.extract_obs_mask(i)).collect(); + + let pool = rayon::ThreadPoolBuilder::new() + .num_threads(num_workers.unwrap_or(0)) + .build() + .map_err(|e| PyErr::new::(e.to_string()))?; + + struct SendWrapper(Box); + unsafe impl Send for SendWrapper {} + unsafe impl Sync for SendWrapper {} + impl pecos_decoders::ObservableDecoder for SendWrapper { + fn decode_to_observables( + &mut self, + syn: &[u8], + ) -> Result { + self.0.decode_to_observables(syn) + } + } + + let errors: usize = pool.install(|| { + // Split into chunks, each chunk gets its own decoder + batch decode + let chunk_size = n.div_ceil(rayon::current_num_threads()); + (0..n) + .collect::>() + .par_chunks(chunk_size.max(1)) + .map(|chunk| { + // Build a fresh decoder for this worker + let mut dec = ObservableSubgraphDecoder::from_dem_windowed( + &dem_str, + &sc, + max_time_radius, + |subgraph| { + let sub_dem = subgraph_to_dem_string(subgraph); + let d = + create_observable_decoder(&sub_dem, &inner_str).map_err(|e| { + pecos_decoders::DecoderError::InternalError(e.to_string()) + })?; + Ok(Box::new(SendWrapper(d)) + as Box) + }, + ) + .unwrap(); + + // Collect chunk syndromes and masks for batch decode + let chunk_syns: Vec> = + chunk.iter().map(|&i| events[i].clone()).collect(); + let chunk_masks: Vec = chunk.iter().map(|&i| masks[i]).collect(); + dec.decode_count_batched(&chunk_syns, &chunk_masks) + .unwrap_or(chunk.len()) + }) + .sum() + }); + + Ok(errors) + } + + /// Number of detectors in each subgraph. + fn subgraph_sizes(&self) -> Vec { + (0..self.inner.num_observables()) + .map(|i| self.inner.subgraph(i).map_or(0, |sg| sg.detector_map.len())) + .collect() + } + + /// Diagnostics: (`num_edges`, `skipped_hyperedges`) for each subgraph. + fn subgraph_diagnostics(&self) -> Vec<(usize, usize)> { + (0..self.inner.num_observables()) + .map(|i| { + self.inner.subgraph(i).map_or((0, 0), |sg| { + (sg.graph.edges.len(), sg.graph.skipped_hyperedges) + }) + }) + .collect() + } + + /// Count ghost edges (3-detector cross-qubit hyperedges) in the DEM. + /// + /// These are the hyperedges that the ghost protocol decomposes for + /// modular per-qubit decoding. Returns (`total_ghost_edges`, `num_qubits`). + #[staticmethod] + fn count_ghost_edges( + dem: &str, + stab_coords: Vec>, + ) -> PyResult<(usize, usize)> { + use pecos_decoder_core::ghost_protocol::extract_ghost_edges_from_dem; + use pecos_decoder_core::observable_subgraph::QubitStabCoords; + + let mut sc = Vec::with_capacity(stab_coords.len()); + for dict in &stab_coords { + let x: Vec<(f64, f64)> = dict + .get_item("X")? + .ok_or_else(|| PyErr::new::("X"))? + .extract()?; + let z: Vec<(f64, f64)> = dict + .get_item("Z")? + .ok_or_else(|| PyErr::new::("Z"))? + .extract()?; + sc.push(QubitStabCoords { + x_positions: x, + z_positions: z, + }); + } + + let edges = extract_ghost_edges_from_dem(dem, &sc); + let num_qubits = sc.len(); + Ok((edges.len(), num_qubits)) + } + + /// Get the per-subgraph DEM strings (graphlike, suitable for windowed decoding). + /// + /// Each string is a DEM with local detector IDs (0..N) that can be + /// passed to windowed or sandwich decoders. + fn subgraph_dems(&self) -> Vec { + (0..self.inner.num_observables()) + .map(|i| { + self.inner + .subgraph(i) + .map_or(String::new(), |sg| subgraph_to_dem_string(&sg.graph)) + }) + .collect() + } + + /// Get the detector map for each subgraph (local → global index mapping). + fn subgraph_detector_maps(&self) -> Vec> { + (0..self.inner.num_observables()) + .map(|i| { + self.inner + .subgraph(i) + .map_or(Vec::new(), |sg| sg.detector_map.clone()) + }) + .collect() + } +} + +// ============================================================================= +// Windowed OSD Decoder (Python class) +// ============================================================================= + +/// Windowed observable subgraph decoder for deep circuits. +/// +/// Splits the DEM into time windows, runs OSD within each window. +/// Prevents the observing region from spanning the full circuit. +/// +/// Args: +/// dem: DEM string. +/// `stab_coords`: Stabilizer coordinates per logical qubit. +/// `inner_decoder`: Inner MWPM decoder type. +/// step: Core window size in time steps. +/// buffer: Buffer size on each side (0 = non-overlapping). +#[pyclass(name = "WindowedOsdDecoder", module = "pecos_rslib.qec")] +pub struct PyWindowedOsdDecoder { + inner: pecos_decoder_core::windowed_osd::WindowedOsdDecoder, +} + +#[pymethods] +impl PyWindowedOsdDecoder { + #[new] + #[pyo3(signature = (dem, stab_coords, inner_decoder="pymatching", step=8, buffer=4))] + fn new( + dem: &str, + stab_coords: Vec>, + inner_decoder: &str, + step: usize, + buffer: usize, + ) -> PyResult { + use pecos_decoder_core::observable_subgraph::QubitStabCoords; + use pecos_decoder_core::windowed_osd::{WindowedOsdConfig, WindowedOsdDecoder}; + + let mut sc = Vec::with_capacity(stab_coords.len()); + for dict in &stab_coords { + let x: Vec<(f64, f64)> = dict + .get_item("X")? + .ok_or_else(|| PyErr::new::("X"))? + .extract()?; + let z: Vec<(f64, f64)> = dict + .get_item("Z")? + .ok_or_else(|| PyErr::new::("Z"))? + .extract()?; + sc.push(QubitStabCoords { + x_positions: x, + z_positions: z, + }); + } + + let config = WindowedOsdConfig { step, buffer }; + + struct SendWrapper(Box); + unsafe impl Send for SendWrapper {} + unsafe impl Sync for SendWrapper {} + impl pecos_decoders::ObservableDecoder for SendWrapper { + fn decode_to_observables( + &mut self, + syndrome: &[u8], + ) -> Result { + self.0.decode_to_observables(syndrome) + } + } + + let inner = WindowedOsdDecoder::from_dem(dem, &sc, &config, |subgraph| { + let sub_dem = subgraph_to_dem_string(subgraph); + let d = create_observable_decoder(&sub_dem, inner_decoder) + .map_err(|e| pecos_decoders::DecoderError::InternalError(e.to_string()))?; + Ok(Box::new(SendWrapper(d)) + as Box) + }) + .map_err(|e| PyErr::new::(e.to_string()))?; + + Ok(Self { inner }) + } + + fn decode(&mut self, syndrome: Vec) -> PyResult { + use pecos_decoder_core::ObservableDecoder; + self.inner + .decode_to_observables(&syndrome) + .map_err(|e| PyErr::new::(e.to_string())) + } + + fn decode_count(&mut self, batch: &PySampleBatch) -> PyResult { + use pecos_decoder_core::ObservableDecoder; + let mut errors = 0usize; + let mut syndrome = vec![0u8; batch.num_detectors]; + for i in 0..batch.num_shots { + batch.extract_syndrome(i, &mut syndrome); + let predicted = self + .inner + .decode_to_observables(&syndrome) + .map_err(|e| PyErr::new::(e.to_string()))?; + if predicted != batch.extract_obs_mask(i) { + errors += 1; + } + } + Ok(errors) + } + + fn num_windows(&self) -> usize { + self.inner.windows.len() + } +} + +// ============================================================================= +// Logical Algorithm Decoder (Python class) +// ============================================================================= + +/// Decoder for logical quantum algorithms with per-segment OSD and +/// Pauli frame propagation at transversal gate boundaries. +/// +/// Built from a descriptor dict produced by +/// ``LogicalCircuitBuilder.build_algorithm_descriptor()``. +/// +/// Supports both batch mode (``decode``, ``decode_count``) and +/// streaming mode (``feed_sparse``, ``flush``, ``reset``). +#[pyclass(name = "LogicalAlgorithmDecoder", module = "pecos_rslib.qec")] +pub struct PyLogicalAlgorithmDecoder { + inner: pecos_decoder_core::logical_algorithm::StreamingLogicalDecoder, +} + +#[pymethods] +impl PyLogicalAlgorithmDecoder { + /// Build from a descriptor dict and inner decoder type. + /// + /// Args: + /// descriptor: Dict from ``LogicalCircuitBuilder.build_algorithm_descriptor()``. + /// `inner_decoder`: Decoder type string for each segment's OSD inner decoder. + #[new] + #[pyo3(signature = (descriptor, inner_decoder="pymatching"))] + fn new( + descriptor: &pyo3::Bound<'_, pyo3::types::PyDict>, + inner_decoder: &str, + ) -> PyResult { + use pecos_decoder_core::logical_algorithm::{ + AlgorithmDescriptor, BoundaryGate, LogicalAlgorithmDecoder, SegmentDescriptor, + }; + use pecos_decoder_core::observable_subgraph::{ObservableSubgraphDecoder, QubitStabCoords}; + + // Parse full DEM and stab_coords for full-circuit OSD + let full_dem: String = descriptor + .get_item("full_dem")? + .ok_or_else(|| PyErr::new::("full_dem"))? + .extract()?; + + // Use first segment's stab_coords as the base (they have the + // original X/Z assignment; the full-circuit DEM uses original coords). + let seg_list: Vec> = descriptor + .get_item("segments")? + .ok_or_else(|| PyErr::new::("segments"))? + .extract()?; + + let num_obs: usize = descriptor + .get_item("num_observables")? + .ok_or_else(|| PyErr::new::("num_observables"))? + .extract()?; + + // Parse stab_coords from the first segment (original orientation) + let first_seg = &seg_list[0]; + let sc_list: Vec> = first_seg + .get_item("stab_coords")? + .ok_or_else(|| PyErr::new::("stab_coords"))? + .extract()?; + let mut rust_sc = Vec::with_capacity(sc_list.len()); + for sc_dict in &sc_list { + let x: Vec<(f64, f64)> = sc_dict + .get_item("X")? + .ok_or_else(|| PyErr::new::("X"))? + .extract()?; + let z: Vec<(f64, f64)> = sc_dict + .get_item("Z")? + .ok_or_else(|| PyErr::new::("Z"))? + .extract()?; + rust_sc.push(QubitStabCoords { + x_positions: x, + z_positions: z, + }); + } + + struct SendWrapper(Box); + unsafe impl Send for SendWrapper {} + unsafe impl Sync for SendWrapper {} + impl pecos_decoders::ObservableDecoder for SendWrapper { + fn decode_to_observables( + &mut self, + syn: &[u8], + ) -> Result { + self.0.decode_to_observables(syn) + } + } + + let inner_str = inner_decoder.to_string(); + + // Build full-circuit OSD from the full DEM + let full_osd = ObservableSubgraphDecoder::from_dem(&full_dem, &rust_sc, |subgraph| { + let sub_dem = subgraph_to_dem_string(subgraph); + let d = create_observable_decoder(&sub_dem, &inner_str) + .map_err(|e| pecos_decoders::DecoderError::InternalError(e.to_string()))?; + Ok(Box::new(SendWrapper(d)) + as Box) + }) + .map_err(|e| PyErr::new::(e.to_string()))?; + + // Parse segment descriptors (for metadata) + let mut seg_descs = Vec::with_capacity(seg_list.len()); + for seg_dict in &seg_list { + let n_det: usize = seg_dict + .get_item("num_detectors")? + .ok_or_else(|| PyErr::new::("num_detectors"))? + .extract()?; + seg_descs.push(SegmentDescriptor { + num_detectors: n_det, + num_observables: num_obs, + }); + } + + // Parse boundary gates + let bg_list: Vec>> = descriptor + .get_item("boundary_gates")? + .ok_or_else(|| PyErr::new::("boundary_gates"))? + .extract()?; + + let mut boundary_gates = Vec::with_capacity(bg_list.len()); + for gates in &bg_list { + let mut bg_vec = Vec::new(); + for gate_dict in gates { + let gate_type: String = gate_dict + .get_item("type")? + .ok_or_else(|| PyErr::new::("type"))? + .extract()?; + match gate_type.as_str() { + "Hadamard" => { + let x: u32 = gate_dict.get_item("x_obs_bit")?.unwrap().extract()?; + let z: u32 = gate_dict.get_item("z_obs_bit")?.unwrap().extract()?; + bg_vec.push(BoundaryGate::Hadamard { + x_obs_bit: x, + z_obs_bit: z, + }); + } + "Cnot" => { + bg_vec.push(BoundaryGate::Cnot { + ctrl_x_bit: gate_dict.get_item("ctrl_x_bit")?.unwrap().extract()?, + ctrl_z_bit: gate_dict.get_item("ctrl_z_bit")?.unwrap().extract()?, + tgt_x_bit: gate_dict.get_item("tgt_x_bit")?.unwrap().extract()?, + tgt_z_bit: gate_dict.get_item("tgt_z_bit")?.unwrap().extract()?, + }); + } + "SGate" => { + let x: u32 = gate_dict.get_item("x_obs_bit")?.unwrap().extract()?; + let z: u32 = gate_dict.get_item("z_obs_bit")?.unwrap().extract()?; + bg_vec.push(BoundaryGate::SGate { + x_obs_bit: x, + z_obs_bit: z, + }); + } + "TGateInjection" => { + let z: u32 = gate_dict.get_item("z_obs_bit")?.unwrap().extract()?; + let a: u32 = gate_dict.get_item("ancilla_z_bit")?.unwrap().extract()?; + bg_vec.push(BoundaryGate::TGateInjection { + z_obs_bit: z, + ancilla_z_bit: a, + }); + } + _ => { + return Err(PyErr::new::(format!( + "Unknown gate type: {gate_type}" + ))); + } + } + } + boundary_gates.push(bg_vec); + } + + let algo_desc = AlgorithmDescriptor { + segments: seg_descs, + boundary_gates, + num_observables: num_obs, + }; + + use pecos_decoder_core::logical_algorithm::StreamingLogicalDecoder; + let algo_dec = LogicalAlgorithmDecoder::new(Box::new(full_osd), algo_desc); + let inner = StreamingLogicalDecoder::new(algo_dec); + Ok(Self { inner }) + } + + // -- Batch mode -- + + /// Decode a single syndrome and return observable flip mask. + fn decode(&mut self, syndrome: Vec) -> PyResult { + self.inner.reset(); + self.inner + .decode_shot(&syndrome) + .map_err(|e| PyErr::new::(e.to_string())) + } + + /// Decode a batch of samples and count logical errors. + fn decode_count(&mut self, batch: &PySampleBatch) -> PyResult { + let detection_events: Vec> = (0..batch.num_shots) + .map(|i| { + let mut s = vec![0u8; batch.num_detectors]; + batch.extract_syndrome(i, &mut s); + s + }) + .collect(); + let observable_masks: Vec = (0..batch.num_shots) + .map(|i| batch.extract_obs_mask(i)) + .collect(); + pecos_decoder_core::logical_algorithm::streaming_decode_count( + &mut self.inner, + &detection_events, + &observable_masks, + ) + .map_err(|e| PyErr::new::(e.to_string())) + } + + // -- Streaming mode -- + + /// Feed sparse detection events: list of (`detector_index`, value) pairs. + fn feed_sparse(&mut self, detectors: Vec<(u32, u8)>) { + self.inner.feed_sparse(&detectors); + } + + /// Feed a dense syndrome (all detectors in order). + fn feed_dense(&mut self, syndrome: Vec) { + self.inner.feed_dense(&syndrome); + } + + /// Decode the accumulated syndrome. Call at segment boundaries or end. + fn flush(&mut self) -> PyResult { + self.inner + .flush() + .map_err(|e| PyErr::new::(e.to_string())) + } + + /// Reset syndrome buffer for the next shot. + fn reset(&mut self) { + self.inner.reset(); + } + + /// Current accumulated observable correction. + fn accumulated_obs(&self) -> u64 { + self.inner.accumulated_obs() + } + + // -- Metadata -- + + /// Number of segments. + fn num_segments(&self) -> usize { + self.inner.num_segments() + } + + /// Rounds fed so far. + fn rounds_fed(&self) -> usize { + self.inner.rounds_fed() + } +} + +// ============================================================================= +// Logical Circuit Decoder with Budget (Python class) +// ============================================================================= + +/// Budget-aware decoder for logical quantum circuits. +/// +/// Selects decode strategy based on available reaction time: +/// - ``"unlimited"``: full-circuit OSD (Clifford circuits, offline) +/// - ``"windowed"``: default windowed OSD (~1ms reaction time) +/// - ``"10ms"``, ``"1000us"``, etc.: explicit reaction time budget +/// +/// The reaction time is the time available at feed-forward decision +/// points (T gates, magic state injection). For Clifford-only circuits, +/// use ``"unlimited"`` since there are no mid-circuit decisions. +/// +/// `Example::` +/// +/// desc = builder.build_algorithm_descriptor(p1=0.001, p2=0.001) +/// decoder = LogicalCircuitDecoder(desc, budget="unlimited") +/// errors = decoder.decode_count(batch) +#[pyclass(name = "LogicalCircuitDecoder", module = "pecos_rslib.qec")] +pub struct PyLogicalCircuitDecoder { + inner: pecos_decoder_core::logical_algorithm::LogicalCircuitDecoder, +} + +#[pymethods] +impl PyLogicalCircuitDecoder { + #[new] + #[pyo3(signature = (descriptor, budget="unlimited", inner_decoder="pymatching"))] + fn new( + descriptor: &pyo3::Bound<'_, pyo3::types::PyDict>, + budget: &str, + inner_decoder: &str, + ) -> PyResult { + use pecos_decoder_core::decode_budget::DecodeBudget; + use pecos_decoder_core::logical_algorithm::{ + AlgorithmDescriptor, BoundaryGate, FullCircuitStrategy, LogicalCircuitDecoder, + SegmentDescriptor, + }; + use pecos_decoder_core::observable_subgraph::{ObservableSubgraphDecoder, QubitStabCoords}; + + // Parse full DEM + let full_dem: String = descriptor + .get_item("full_dem")? + .ok_or_else(|| PyErr::new::("full_dem"))? + .extract()?; + + let seg_list: Vec> = descriptor + .get_item("segments")? + .ok_or_else(|| PyErr::new::("segments"))? + .extract()?; + + let num_obs: usize = descriptor + .get_item("num_observables")? + .ok_or_else(|| PyErr::new::("num_observables"))? + .extract()?; + + // Parse stab_coords from first segment + let first_seg = &seg_list[0]; + let sc_list: Vec> = first_seg + .get_item("stab_coords")? + .ok_or_else(|| PyErr::new::("stab_coords"))? + .extract()?; + let mut rust_sc = Vec::with_capacity(sc_list.len()); + for sc_dict in &sc_list { + let x: Vec<(f64, f64)> = sc_dict + .get_item("X")? + .ok_or_else(|| PyErr::new::("X"))? + .extract()?; + let z: Vec<(f64, f64)> = sc_dict + .get_item("Z")? + .ok_or_else(|| PyErr::new::("Z"))? + .extract()?; + rust_sc.push(QubitStabCoords { + x_positions: x, + z_positions: z, + }); + } + let num_qubits = rust_sc.len(); + + struct SendWrapper(Box); + unsafe impl Send for SendWrapper {} + unsafe impl Sync for SendWrapper {} + impl pecos_decoders::ObservableDecoder for SendWrapper { + fn decode_to_observables( + &mut self, + syn: &[u8], + ) -> Result { + self.0.decode_to_observables(syn) + } + } + + let inner_str = inner_decoder.to_string(); + let full_osd = ObservableSubgraphDecoder::from_dem(&full_dem, &rust_sc, |subgraph| { + let sub_dem = subgraph_to_dem_string(subgraph); + let d = create_observable_decoder(&sub_dem, &inner_str) + .map_err(|e| pecos_decoders::DecoderError::InternalError(e.to_string()))?; + Ok(Box::new(SendWrapper(d)) + as Box) + }) + .map_err(|e| PyErr::new::(e.to_string()))?; + + // Parse segments + let mut seg_descs = Vec::with_capacity(seg_list.len()); + for seg_dict in &seg_list { + let n_det: usize = seg_dict + .get_item("num_detectors")? + .ok_or_else(|| PyErr::new::("num_detectors"))? + .extract()?; + seg_descs.push(SegmentDescriptor { + num_detectors: n_det, + num_observables: num_obs, + }); + } + + // Parse boundary gates + let bg_list: Vec>> = descriptor + .get_item("boundary_gates")? + .ok_or_else(|| PyErr::new::("boundary_gates"))? + .extract()?; + + let mut boundary_gates = Vec::with_capacity(bg_list.len()); + for gates in &bg_list { + let mut bg_vec = Vec::new(); + for gate_dict in gates { + let gate_type: String = gate_dict + .get_item("type")? + .ok_or_else(|| PyErr::new::("type"))? + .extract()?; + match gate_type.as_str() { + "Hadamard" => { + bg_vec.push(BoundaryGate::Hadamard { + x_obs_bit: gate_dict.get_item("x_obs_bit")?.unwrap().extract()?, + z_obs_bit: gate_dict.get_item("z_obs_bit")?.unwrap().extract()?, + }); + } + "Cnot" => { + bg_vec.push(BoundaryGate::Cnot { + ctrl_x_bit: gate_dict.get_item("ctrl_x_bit")?.unwrap().extract()?, + ctrl_z_bit: gate_dict.get_item("ctrl_z_bit")?.unwrap().extract()?, + tgt_x_bit: gate_dict.get_item("tgt_x_bit")?.unwrap().extract()?, + tgt_z_bit: gate_dict.get_item("tgt_z_bit")?.unwrap().extract()?, + }); + } + "SGate" => { + bg_vec.push(BoundaryGate::SGate { + x_obs_bit: gate_dict.get_item("x_obs_bit")?.unwrap().extract()?, + z_obs_bit: gate_dict.get_item("z_obs_bit")?.unwrap().extract()?, + }); + } + "TGateInjection" => { + let z: u32 = gate_dict.get_item("z_obs_bit")?.unwrap().extract()?; + let a: u32 = gate_dict.get_item("ancilla_z_bit")?.unwrap().extract()?; + bg_vec.push(BoundaryGate::TGateInjection { + z_obs_bit: z, + ancilla_z_bit: a, + }); + } + _ => { + return Err(PyErr::new::(format!( + "Unknown gate type: {gate_type}" + ))); + } + } + } + boundary_gates.push(bg_vec); + } + + let algo_desc = AlgorithmDescriptor { + segments: seg_descs, + boundary_gates, + num_observables: num_obs, + }; - let mut rng = match seed { - Some(s) => PecosRng::seed_from_u64(s), - None => PecosRng::seed_from_u64(rand::rng().random()), + // Select budget: "unlimited" for full-circuit, "windowed" for + // bounded-latency, or a cycle time in microseconds like "1000us". + let distance = (num_qubits as f64).sqrt() as usize; + let decode_budget = match budget { + "unlimited" | "offline" => DecodeBudget::unlimited(), + "windowed" => { + DecodeBudget::from_reaction_time(std::time::Duration::from_millis(1), distance) + } + s if s.ends_with("us") => { + let us: u64 = s[..s.len() - 2].parse().map_err(|_| { + PyErr::new::(format!( + "Invalid cycle time: {s}" + )) + })?; + DecodeBudget::from_reaction_time(std::time::Duration::from_micros(us), distance) + } + s if s.ends_with("ms") => { + let ms: u64 = s[..s.len() - 2].parse().map_err(|_| { + PyErr::new::(format!( + "Invalid cycle time: {s}" + )) + })?; + DecodeBudget::from_reaction_time(std::time::Duration::from_millis(ms), distance) + } + _ => { + return Err(PyErr::new::(format!( + "Unknown budget: {budget}. Use: unlimited, windowed, or a cycle time like 1000us, 10ms" + ))); + } }; - self.inner.sample(&mut rng) + // Select strategy based on budget. + let strategy: Box = + if decode_budget.is_unlimited() { + // Unlimited: full-circuit OSD (maximum accuracy) + Box::new(FullCircuitStrategy::new(Box::new(full_osd))) + } else { + // Windowed: per-subgraph sandwich decoding. + // Extract per-subgraph DEMs and detector maps from the full OSD. + use pecos_decoder_core::logical_algorithm::WindowedOsdStrategy; + + let mut sub_dems = Vec::new(); + let mut det_maps = Vec::new(); + for i in 0..full_osd.num_observables() { + if let Some(sg) = full_osd.subgraph(i) { + sub_dems.push(subgraph_to_dem_string(&sg.graph)); + det_maps.push(sg.detector_map.clone()); + } + } + + let d = decode_budget.code_distance; + let buf = decode_budget.overlap_rounds.min(d * 2); // cap at 2d + let windowed_str = if buf > 0 { + format!("windowed:step={d},buf={buf},wmax=2.5") + } else { + // No overlap: use plain PM (faster, but accuracy limited + // to non-overlapping windowed matching) + format!("windowed:step={d},buf=0") + }; + + let wosd = WindowedOsdStrategy::new(sub_dems, det_maps, |dem_str| { + let dec = create_observable_decoder(dem_str, &windowed_str) + .map_err(|e| pecos_decoders::DecoderError::InternalError(e.to_string()))?; + Ok(Box::new(SendWrapper(dec)) + as Box) + }) + .map_err(|e| PyErr::new::(e.to_string()))?; + + Box::new(wosd) + }; + + let inner = LogicalCircuitDecoder::new(algo_desc, strategy, decode_budget, num_qubits); + Ok(Self { inner }) } - /// Sample multiple shots from this DEM. - /// - /// Args: - /// `num_shots`: Number of shots to sample. - /// seed: Optional random seed for reproducibility. - /// - /// Returns: - /// Tuple of (`all_detector_events`, `all_observable_flips`). - #[pyo3(signature = (num_shots, seed=None))] - fn sample_batch( - &self, - num_shots: usize, - seed: Option, - ) -> (Vec>, Vec>) { - use pecos_random::PecosRng; - use rand::RngExt; + /// Decode a single syndrome. + fn decode(&mut self, syndrome: Vec) -> PyResult { + use pecos_decoder_core::ObservableDecoder; + self.inner + .decode_to_observables(&syndrome) + .map_err(|e| PyErr::new::(e.to_string())) + } - let mut rng = match seed { - Some(s) => PecosRng::seed_from_u64(s), - None => PecosRng::seed_from_u64(rand::rng().random()), - }; + /// Decode a batch and count errors. + fn decode_count(&mut self, batch: &PySampleBatch) -> PyResult { + let detection_events: Vec> = (0..batch.num_shots) + .map(|i| { + let mut s = vec![0u8; batch.num_detectors]; + batch.extract_syndrome(i, &mut s); + s + }) + .collect(); + let observable_masks: Vec = (0..batch.num_shots) + .map(|i| batch.extract_obs_mask(i)) + .collect(); + self.inner + .decode_count(&detection_events, &observable_masks) + .map_err(|e| PyErr::new::(e.to_string())) + } - self.inner.sample_batch(num_shots, &mut rng) + /// Number of segments. + fn num_segments(&self) -> usize { + self.inner.num_segments() } - /// Convert to an optimized `DemSampler` for fast batch sampling. - /// - /// The `DemSampler` uses geometric skip sampling and parallel chunked - /// processing, which is significantly faster than `sample_batch` for - /// large shot counts and low error rates. - /// - /// Returns: - /// `DemSampler`: Optimized sampler for this DEM. - /// - /// Example: - /// >>> dem = `ParsedDem.from_string("error(0.01)` D0 D1") - /// >>> sampler = `dem.to_dem_sampler()` - /// >>> stats = `sampler.sample_statistics(100000`, seed=42) - fn to_dem_sampler(&self) -> PyDemSampler { - PyDemSampler { - inner: self.inner.to_dem_sampler(), - } + /// Total detectors. + fn total_detectors(&self) -> usize { + self.inner.total_detectors() } - fn __repr__(&self) -> String { - format!( - "ParsedDem(mechanisms={}, detectors={}, observables={})", - self.inner.mechanisms.len(), - self.inner.num_detectors, - self.inner.num_observables - ) + /// Whether the circuit has feed-forward decision points (T gates). + /// If False, the reaction time budget doesn't matter — Clifford only. + fn has_decision_points(&self) -> bool { + self.inner.has_decision_points() + } + + /// Number of decision points. + fn num_decision_points(&self) -> usize { + self.inner.num_decision_points() + } + + /// Reset for next shot. + fn reset(&mut self) { + self.inner.reset(); } } -/// Compare two DEMs for exact mechanism match. -/// -/// This comparison aggregates mechanisms by effect and compares probabilities. -/// Appropriate for non-decomposed DEMs or when exact match is required. +// ============================================================================= +// Correlation Analysis Functions +// ============================================================================= + +/// Compute a detector flip frequency matrix from fired-detector lists. /// /// Args: -/// dem1: First DEM string or `ParsedDem`. -/// dem2: Second DEM string or `ParsedDem`. -/// `prob_tolerance`: Relative tolerance for probability comparison (default 1e-6). +/// fired_per_shot: List of lists, each inner list contains the detector +/// indices that fired in that shot (sorted ascending). +/// num_detectors: Total number of detectors. /// /// Returns: -/// `EquivalenceResult` with comparison statistics. -/// -/// Example: -/// >>> result = `compare_dems_exact(dem1_str`, `dem2_str`, `prob_tolerance=0.001`) -/// >>> if result.equivalent: -/// ... print("DEMs are equivalent") +/// Flat list of length ``num_detectors^2`` (row-major). Diagonal entries +/// are marginal rates; off-diagonal ``M[i*n+j]`` = 0.5 * P(i AND j fire). #[pyfunction] -#[pyo3(signature = (dem1, dem2, prob_tolerance=1e-6))] -fn compare_dems_exact( - dem1: &str, - dem2: &str, - prob_tolerance: f64, -) -> PyResult { - let parsed1 = dem1 - .parse::() - .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("DEM1 parse error: {e}")))?; - let parsed2 = dem2 - .parse::() - .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("DEM2 parse error: {e}")))?; - - let inner = rust_compare_dems_exact(&parsed1, &parsed2, prob_tolerance); - Ok(PyEquivalenceResult { inner }) +#[pyo3(signature = (fired_per_shot, num_detectors))] +fn detector_flip_matrix(fired_per_shot: Vec>, num_detectors: usize) -> Vec { + pecos_qec::fault_tolerance::correlation::flip_matrix_from_fired(&fired_per_shot, num_detectors) } -/// Compare two DEMs statistically by sampling. -/// -/// This is the most robust comparison method as it accounts for all -/// decomposition strategies and probability combinations. It compares -/// the joint distribution of syndrome patterns, not just marginal rates. +/// Compute per-round detector flip frequency matrices. /// -/// Args: -/// dem1: First DEM string or `ParsedDem`. -/// dem2: Second DEM string or `ParsedDem`. -/// `num_shots`: Number of shots for sampling (default 100,000). -/// seed: Random seed (default 42). -/// tolerance: Maximum relative difference to consider equivalent (default 0.05). +/// Returns a list of flat matrices, one per round. +#[pyfunction] +#[pyo3(signature = (fired_per_shot, num_detectors, dets_per_round))] +fn detector_flip_matrices_by_round( + fired_per_shot: Vec>, + num_detectors: usize, + dets_per_round: usize, +) -> Vec> { + pecos_qec::fault_tolerance::correlation::flip_matrices_by_round( + &fired_per_shot, + num_detectors, + dets_per_round, + ) +} + +/// Compute k-body detector firing rates up to a given order. /// -/// Returns: -/// `EquivalenceResult` with comparison statistics. +/// Returns a list of ``(detector_indices, rate)`` pairs where +/// ``detector_indices`` is a tuple of sorted detector indices. +#[pyfunction] +#[pyo3(signature = (fired_per_shot, num_detectors, max_order=3))] +fn detector_k_body_rates( + fired_per_shot: Vec>, + num_detectors: usize, + max_order: usize, +) -> Vec<(Vec, f64)> { + pecos_qec::fault_tolerance::correlation::k_body_rates(&fired_per_shot, num_detectors, max_order) + .into_iter() + .collect() +} + +/// Compute per-round k-body detector firing rates. /// -/// Example: -/// >>> result = `compare_dems_statistical(dem1_str`, `dem2_str`, `num_shots=50000`) -/// >>> print(f"Correlation: {result.correlation}") +/// Returns a list (one per round) of lists of ``(local_indices, rate)`` pairs. #[pyfunction] -#[pyo3(signature = (dem1, dem2, num_shots=100_000, seed=42, tolerance=0.05))] -fn compare_dems_statistical( - dem1: &str, - dem2: &str, - num_shots: usize, - seed: u64, - tolerance: f64, -) -> PyResult { - let parsed1 = dem1 - .parse::() - .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("DEM1 parse error: {e}")))?; - let parsed2 = dem2 - .parse::() - .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("DEM2 parse error: {e}")))?; +#[pyo3(signature = (fired_per_shot, num_detectors, dets_per_round, max_order=3))] +fn detector_k_body_rates_by_round( + fired_per_shot: Vec>, + num_detectors: usize, + dets_per_round: usize, + max_order: usize, +) -> Vec, f64)>> { + pecos_qec::fault_tolerance::correlation::k_body_rates_by_round( + &fired_per_shot, + num_detectors, + dets_per_round, + max_order, + ) + .into_iter() + .map(|m| m.into_iter().collect()) + .collect() +} - let inner = rust_compare_dems_statistical(&parsed1, &parsed2, num_shots, seed, tolerance); - Ok(PyEquivalenceResult { inner }) +/// Compare two flat flip matrices. Returns (max_rel_err, frob_rel_err, worst_i, worst_j). +#[pyfunction] +#[pyo3(signature = (sim, dem, num_detectors, min_rate=0.0005))] +fn compare_flip_matrices_rs( + sim: Vec, + dem: Vec, + num_detectors: usize, + min_rate: f64, +) -> (f64, f64, usize, usize) { + pecos_qec::fault_tolerance::correlation::compare_flip_matrices( + &sim, + &dem, + num_detectors, + min_rate, + ) } -/// Convenience function to verify DEM equivalence. +/// Compare k-body rates grouped by order. /// /// Args: -/// dem1: First DEM string. -/// dem2: Second DEM string. -/// method: Comparison method - "exact" or "statistical" (default "exact"). -/// `prob_tolerance`: For exact: probability tolerance (default 1e-6). -/// `num_shots`: For statistical: number of shots (default 100,000). -/// tolerance: For statistical: rate tolerance (default 0.05). -/// seed: For statistical: random seed (default 42). +/// sim: List of ``(detector_indices, rate)`` from simulation. +/// dem: List of ``(detector_indices, rate)`` from DEM. +/// min_rate: Minimum rate to consider. /// /// Returns: -/// True if DEMs are equivalent within tolerance. -/// -/// Example: -/// >>> if `verify_dem_equivalence(dem1`, dem2, method="exact"): -/// ... print("DEMs match exactly") +/// List of ``(order, max_rel_err, rms_rel_err, worst_event)`` tuples. #[pyfunction] -#[pyo3(signature = (dem1, dem2, method="exact", prob_tolerance=1e-6, num_shots=100_000, tolerance=0.05, seed=42))] -fn verify_dem_equivalence( - dem1: &str, - dem2: &str, - method: &str, - prob_tolerance: f64, - num_shots: usize, - tolerance: f64, - seed: u64, -) -> PyResult { - let comparison_method = match method { - "exact" => RustComparisonMethod::Exact { prob_tolerance }, - "statistical" => RustComparisonMethod::Statistical { - num_shots, - seed, - tolerance, - }, - _ => { - return Err(pyo3::exceptions::PyValueError::new_err( - "method must be 'exact' or 'statistical'", - )); - } - }; - - rust_verify_dem_equivalence(dem1, dem2, &comparison_method) - .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string())) +#[pyo3(signature = (sim, dem, min_rate=0.0005))] +fn compare_k_body_rates_rs( + sim: Vec<(Vec, f64)>, + dem: Vec<(Vec, f64)>, + min_rate: f64, +) -> Vec<(usize, f64, f64, Vec)> { + let sim_map: std::collections::BTreeMap, f64> = sim.into_iter().collect(); + let dem_map: std::collections::BTreeMap, f64> = dem.into_iter().collect(); + pecos_qec::fault_tolerance::correlation::compare_k_body(&sim_map, &dem_map, min_rate) + .into_iter() + .map(|(order, (me, rms, worst))| (order, me, rms, worst)) + .collect() } -/// Assert that two DEMs are equivalent, raising an error if not. +/// Fit DEM mechanism probabilities to match target detector marginals. /// -/// This is a convenience function for testing that raises `AssertionError` -/// if the DEMs are not equivalent. +/// Takes the mechanism structure (from a stochastic DEM) and exact +/// per-detector marginals (from Heisenberg EEG), and adjusts mechanism +/// probabilities so the DEM reproduces those marginals. /// /// Args: -/// dem1: First DEM string. -/// dem2: Second DEM string. -/// method: Comparison method - "exact" or "statistical" (default "exact"). -/// `prob_tolerance`: For exact: probability tolerance (default 1e-6). -/// `num_shots`: For statistical: number of shots (default 100,000). -/// tolerance: For statistical: rate tolerance (default 0.05). -/// seed: For statistical: random seed (default 42). -/// -/// Raises: -/// `AssertionError`: If DEMs are not equivalent. +/// mechanisms: List of ``(probability, detector_indices, observable_indices)`` +/// from the stochastic DEM. +/// target_marginals: Exact per-detector rates from Heisenberg EEG. +/// max_iterations: Maximum fitting iterations (default 200). +/// tolerance: Convergence threshold (default 1e-12). /// -/// Example: -/// >>> `assert_dems_equivalent(dem1`, dem2, method="exact") # Raises if not equivalent +/// Returns: +/// Tuple of ``(fitted_mechanisms, residuals)`` where +/// ``fitted_mechanisms`` has the same format as input but with +/// adjusted probabilities, and ``residuals`` is the per-detector +/// absolute error after fitting. #[pyfunction] -#[pyo3(signature = (dem1, dem2, method="exact", prob_tolerance=1e-6, num_shots=100_000, tolerance=0.05, seed=42))] -fn assert_dems_equivalent( - dem1: &str, - dem2: &str, - method: &str, - prob_tolerance: f64, - num_shots: usize, +#[pyo3(signature = (mechanisms, target_marginals, max_iterations=200, tolerance=1e-12))] +fn fit_dem_to_marginals( + mechanisms: Vec<(f64, Vec, Vec)>, + target_marginals: Vec, + max_iterations: usize, tolerance: f64, - seed: u64, -) -> PyResult<()> { - let parsed1 = dem1 - .parse::() - .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("DEM1 parse error: {e}")))?; - let parsed2 = dem2 - .parse::() - .map_err(|e| pyo3::exceptions::PyValueError::new_err(format!("DEM2 parse error: {e}")))?; +) -> (Vec<(f64, Vec, Vec)>, Vec) { + use pecos_qec::fault_tolerance::correlation::{ + DemMechanism, fit_dem_to_marginals as fit_inner, + }; - let result = match method { - "exact" => rust_compare_dems_exact(&parsed1, &parsed2, prob_tolerance), - "statistical" => { - rust_compare_dems_statistical(&parsed1, &parsed2, num_shots, seed, tolerance) - } - _ => { - return Err(pyo3::exceptions::PyValueError::new_err( - "method must be 'exact' or 'statistical'", - )); - } + let mechs: Vec = mechanisms + .iter() + .map(|(p, d, o)| DemMechanism { + probability: *p, + detectors: d.clone(), + observables: o.clone(), + }) + .collect(); + + let (fitted, residuals) = fit_inner(&mechs, &target_marginals, max_iterations, tolerance); + + let result: Vec<(f64, Vec, Vec)> = fitted + .iter() + .map(|m| (m.probability, m.detectors.clone(), m.observables.clone())) + .collect(); + + (result, residuals) +} + +/// Format DEM mechanisms as a Stim DEM string. +#[pyfunction] +fn mechanisms_to_dem_string(mechanisms: Vec<(f64, Vec, Vec)>) -> String { + use pecos_qec::fault_tolerance::correlation::{ + DemMechanism, mechanisms_to_dem_string as fmt_inner, }; - if result.equivalent { - Ok(()) - } else { - let msg = format!( - "DEMs are not equivalent: max_rate_diff={:.6}, only_in_dem1={:?}, only_in_dem2={:?}", - result.max_rate_difference, result.details.only_in_dem1, result.details.only_in_dem2 - ); - Err(pyo3::exceptions::PyAssertionError::new_err(msg)) + let mechs: Vec = mechanisms + .iter() + .map(|(p, d, o)| DemMechanism { + probability: *p, + detectors: d.clone(), + observables: o.clone(), + }) + .collect(); + + fmt_inner(&mechs) +} + +/// Query whether a decoder type requires decomposed (graphlike) DEMs. +/// +/// Returns ``"graphlike"`` for MWPM decoders that need decomposed DEMs +/// (hyperedges cause errors), ``"any"`` for decoders that handle both +/// raw and decomposed DEMs. +/// +/// Raises ``ValueError`` for unknown decoder types. +#[pyfunction] +fn decoder_dem_requirement(decoder_type: &str) -> PyResult { + let base = decoder_type.split(':').next().unwrap_or(decoder_type); + match base { + "pymatching" + | "pymatching_uncorrelated" + | "fusion_blossom" + | "fusion_blossom_serial" + | "fusion_blossom_parallel" + | "fusion_blossom_correlated" + | "pecos_uf" + | "pecos_uf_correlated" + | "windowed" + | "k_mwpm" + | "perturbed_fb_corr" + | "perturbed_fb" + | "ensemble" => Ok("graphlike".to_string()), + "tesseract" | "astar" | "astar_full" | "bp_osd" | "bp_lsd" | "union_find" + | "min_sum_bp" | "relay_bp" | "mwpf" | "chromobius" => Ok("any".to_string()), + _ => Err(pyo3::exceptions::PyValueError::new_err(format!( + "Unknown decoder type: {decoder_type:?}", + ))), } } -// --- Module Registration --- +// ============================================================================= +// Module Registration +// ============================================================================= /// Register the QEC fault tolerance module. pub fn register_qec_module(m: &Bound<'_, PyModule>) -> PyResult<()> { @@ -2515,9 +5525,13 @@ pub fn register_qec_module(m: &Bound<'_, PyModule>) -> PyResult<()> { qec.add_class::()?; qec.add_class::()?; qec.add_class::()?; - qec.add_class::()?; - qec.add_class::()?; - qec.add_class::()?; + qec.add_class::()?; + qec.add_class::()?; + qec.add_class::()?; + qec.add_class::()?; + qec.add_class::()?; + qec.add_class::()?; + qec.add_class::()?; qec.add_class::()?; qec.add_class::()?; qec.add_class::()?; @@ -2529,6 +5543,17 @@ pub fn register_qec_module(m: &Bound<'_, PyModule>) -> PyResult<()> { qec.add_function(wrap_pyfunction!(verify_dem_equivalence, &qec)?)?; qec.add_function(wrap_pyfunction!(assert_dems_equivalent, &qec)?)?; + // Correlation analysis + qec.add_function(wrap_pyfunction!(detector_flip_matrix, &qec)?)?; + qec.add_function(wrap_pyfunction!(detector_flip_matrices_by_round, &qec)?)?; + qec.add_function(wrap_pyfunction!(detector_k_body_rates, &qec)?)?; + qec.add_function(wrap_pyfunction!(detector_k_body_rates_by_round, &qec)?)?; + qec.add_function(wrap_pyfunction!(compare_flip_matrices_rs, &qec)?)?; + qec.add_function(wrap_pyfunction!(compare_k_body_rates_rs, &qec)?)?; + qec.add_function(wrap_pyfunction!(fit_dem_to_marginals, &qec)?)?; + qec.add_function(wrap_pyfunction!(mechanisms_to_dem_string, &qec)?)?; + qec.add_function(wrap_pyfunction!(decoder_dem_requirement, &qec)?)?; + // Add Pauli constants qec.add("PAULI_I", 0u8)?; qec.add("PAULI_X", 1u8)?; diff --git a/python/pecos-rslib/src/lib.rs b/python/pecos-rslib/src/lib.rs index 6239baa96..d2c529a08 100644 --- a/python/pecos-rslib/src/lib.rs +++ b/python/pecos-rslib/src/lib.rs @@ -25,7 +25,6 @@ mod bit_int_bindings; mod bit_uint_bindings; mod byte_message_bindings; mod clifford_rep_bindings; -mod clifford_rz_bindings; mod coin_toss_bindings; mod dag_circuit_bindings; mod decoder_bindings; @@ -58,6 +57,7 @@ mod sparse_sim; mod sparse_stab_bindings; mod sparse_stab_engine_bindings; mod stab_bindings; +mod stab_vec_bindings; mod stabilizer_code_bindings; mod stabilizer_group_bindings; mod state_vec_bindings; @@ -72,7 +72,6 @@ mod wasm_program_bindings; use bit_int_bindings::PyBitInt; use bit_uint_bindings::PyBitUInt; use byte_message_bindings::{PyByteMessage, PyByteMessageBuilder}; -use clifford_rz_bindings::PyCliffordRz; use coin_toss_bindings::PyCoinToss; use engine_builders::{PyHugr, PyPhirJson, PyQasm, PyQis}; use pauli_prop_bindings::PyPauliProp; @@ -82,6 +81,7 @@ use pyo3::prelude::*; use sparse_stab_bindings::PySparseStab; use sparse_stab_engine_bindings::PySparseStabEngine; use stab_bindings::PyStabilizer; +use stab_vec_bindings::PyStabVec; use state_vec_bindings::PyStateVec; use state_vec_engine_bindings::PyStateVecEngine; #[cfg(feature = "wasm")] @@ -229,7 +229,7 @@ fn pecos_rslib(_py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> { } } - m.add_class::()?; + m.add_class::()?; m.add_class::()?; m.add_class::()?; m.add_class::()?; @@ -319,7 +319,7 @@ fn pecos_rslib(_py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> { // Register engine builder functions m.add_function(wrap_pyfunction!(engine_builders::qasm_engine, m)?)?; m.add_function(wrap_pyfunction!(engine_builders::qis_engine, m)?)?; - m.add_function(wrap_pyfunction!(engine_builders::selene_runtime, m)?)?; + m.add_function(wrap_pyfunction!(engine_builders::selene_engine, m)?)?; m.add_function(wrap_pyfunction!(engine_builders::phir_json_engine, m)?)?; m.add_function(wrap_pyfunction!(engine_builders::phir_engine, m)?)?; m.add_function(wrap_pyfunction!(engine_builders::sim_builder, m)?)?; @@ -332,7 +332,7 @@ fn pecos_rslib(_py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> { m.add_function(wrap_pyfunction!(engine_builders::state_vector, m)?)?; m.add_function(wrap_pyfunction!(engine_builders::sparse_stab, m)?)?; m.add_function(wrap_pyfunction!(engine_builders::stabilizer, m)?)?; - m.add_function(wrap_pyfunction!(engine_builders::clifford_rz, m)?)?; + m.add_function(wrap_pyfunction!(engine_builders::stab_vec, m)?)?; m.add_function(wrap_pyfunction!(engine_builders::density_matrix, m)?)?; m.add_function(wrap_pyfunction!(engine_builders::coin_toss, m)?)?; diff --git a/python/pecos-rslib/src/namespace_modules.rs b/python/pecos-rslib/src/namespace_modules.rs index e2a7e4493..865d6d718 100644 --- a/python/pecos-rslib/src/namespace_modules.rs +++ b/python/pecos-rslib/src/namespace_modules.rs @@ -52,7 +52,7 @@ pub fn register_quantum_module(parent: &Bound<'_, PyModule>) -> PyResult<()> { quantum.add("state_vector", parent.getattr("state_vector")?)?; quantum.add("sparse_stab", parent.getattr("sparse_stab")?)?; quantum.add("stabilizer", parent.getattr("stabilizer")?)?; - quantum.add("clifford_rz", parent.getattr("clifford_rz")?)?; + quantum.add("stab_vec", parent.getattr("stab_vec")?)?; quantum.add("density_matrix", parent.getattr("density_matrix")?)?; quantum.add("coin_toss", parent.getattr("coin_toss")?)?; @@ -70,8 +70,8 @@ pub fn register_quantum_module(parent: &Bound<'_, PyModule>) -> PyResult<()> { parent.getattr("StabilizerEngineBuilder")?, )?; quantum.add( - "CliffordRzEngineBuilder", - parent.getattr("CliffordRzEngineBuilder")?, + "StabVecEngineBuilder", + parent.getattr("StabVecEngineBuilder")?, )?; quantum.add( "DensityMatrixEngineBuilder", diff --git a/python/pecos-rslib/src/pauli_bindings.rs b/python/pecos-rslib/src/pauli_bindings.rs index bd5e22a93..943132a65 100644 --- a/python/pecos-rslib/src/pauli_bindings.rs +++ b/python/pecos-rslib/src/pauli_bindings.rs @@ -16,6 +16,9 @@ //! to Python, allowing quantum error models to use native Pauli representations //! instead of string-based arrays. +// pyfunction generates internal modules named after the function (X, Y, Z) +#![allow(non_snake_case)] + use crate::prelude::{ Pauli as RustPauli, PauliOperator, PauliString as RustPauliString, QuarterPhase, QubitId, }; @@ -419,11 +422,119 @@ impl PauliString { fn anticommutes_with(&self, other: &PauliString) -> bool { !self.inner.commutes_with(&other.inner) } + + // ---- Single-qubit constructors ---- + + /// Create X on a single qubit: `PauliString.X(3)` + #[staticmethod] + #[allow(non_snake_case)] + fn X(qubit: usize) -> Self { + PauliString { + inner: RustPauliString::x(qubit), + } + } + + /// Create Y on a single qubit: `PauliString.Y(3)` + #[staticmethod] + #[allow(non_snake_case)] + fn Y(qubit: usize) -> Self { + PauliString { + inner: RustPauliString::y(qubit), + } + } + + /// Create Z on a single qubit: `PauliString.Z(3)` + #[staticmethod] + #[allow(non_snake_case)] + fn Z(qubit: usize) -> Self { + PauliString { + inner: RustPauliString::z(qubit), + } + } + + /// Create identity: `PauliString.I()` + #[staticmethod] + #[allow(non_snake_case)] + fn I() -> Self { + PauliString { + inner: RustPauliString::identity(), + } + } + + // ---- Tensor product operator (&) ---- + + /// Tensor product: `PauliString.X(0) & PauliString.Z(1)` + fn __and__(&self, other: &PauliString) -> Self { + PauliString { + inner: self.inner.clone() & other.inner.clone(), + } + } + + /// Pauli multiplication: `PauliString.X(0) * PauliString.Y(0)` + fn __mul__(&self, other: &PauliString) -> Self { + PauliString { + inner: self.inner.clone() * other.inner.clone(), + } + } + + /// Negation: `-PauliString.X(0)` + fn __neg__(&self) -> Self { + PauliString { + inner: -self.inner.clone(), + } + } + + /// Equality check. + fn __eq__(&self, other: &PauliString) -> bool { + self.inner == other.inner + } + + /// Number of non-identity Pauli operators. + fn weight(&self) -> usize { + self.inner.weight() + } + + /// List of qubit indices with non-identity operators. + fn qubits(&self) -> Vec { + self.inner.qubits() + } +} + +// Module-level constructor functions for `from pecos import X, Y, Z` + +/// Create a single-qubit X `PauliString`: `X(3)` +#[pyfunction] +#[allow(non_snake_case)] +pub fn X(qubit: usize) -> PauliString { + PauliString { + inner: RustPauliString::x(qubit), + } +} + +/// Create a single-qubit Y `PauliString`: `Y(3)` +#[pyfunction] +#[allow(non_snake_case)] +pub fn Y(qubit: usize) -> PauliString { + PauliString { + inner: RustPauliString::y(qubit), + } +} + +/// Create a single-qubit Z `PauliString`: `Z(3)` +#[pyfunction] +#[allow(non_snake_case)] +pub fn Z(qubit: usize) -> PauliString { + PauliString { + inner: RustPauliString::z(qubit), + } } /// Register Pauli types with Python module pub fn register_pauli_types(m: &Bound<'_, PyModule>) -> PyResult<()> { m.add_class::()?; m.add_class::()?; + m.add_function(pyo3::wrap_pyfunction!(X, m)?)?; + m.add_function(pyo3::wrap_pyfunction!(Y, m)?)?; + m.add_function(pyo3::wrap_pyfunction!(Z, m)?)?; Ok(()) } diff --git a/python/pecos-rslib/src/phir_json_bridge.rs b/python/pecos-rslib/src/phir_json_bridge.rs index 5a1bfb368..66979af82 100644 --- a/python/pecos-rslib/src/phir_json_bridge.rs +++ b/python/pecos-rslib/src/phir_json_bridge.rs @@ -216,18 +216,12 @@ impl PhirJsonEngine { let params_dict = PyDict::new(py); // Use string matching instead of GateType enum match op.gate_type.to_string().as_str() { - "RZ" => { - if !op.params.is_empty() { - params_dict.set_item("theta", op.params[0])?; - } + "RZ" if !op.params.is_empty() => { + params_dict.set_item("theta", op.params[0])?; } - "R1XY" => { - if op.params.len() >= 2 { - params_dict.set_item( - "angles", - [op.params[0], op.params[1]], - )?; - } + "R1XY" if op.params.len() >= 2 => { + params_dict + .set_item("angles", [op.params[0], op.params[1]])?; } #[allow(clippy::match_same_arms)] "Measure" => { diff --git a/python/pecos-rslib/src/py_foreign_simulator.rs b/python/pecos-rslib/src/py_foreign_simulator.rs index 62647bc73..b35eaf917 100644 --- a/python/pecos-rslib/src/py_foreign_simulator.rs +++ b/python/pecos-rslib/src/py_foreign_simulator.rs @@ -116,6 +116,16 @@ impl QuantumSimulator for PyForeignSimulator { }); self } + + fn num_qubits(&self) -> usize { + Python::attach(|py| { + self.inner + .call_method0(py, "num_qubits") + .expect("Python simulator num_qubits() failed") + .extract::(py) + .expect("num_qubits() must return an integer") + }) + } } impl CliffordGateable for PyForeignSimulator { diff --git a/python/pecos-rslib/src/sim.rs b/python/pecos-rslib/src/sim.rs index a357a42b8..2228fa4be 100644 --- a/python/pecos-rslib/src/sim.rs +++ b/python/pecos-rslib/src/sim.rs @@ -10,7 +10,7 @@ use crate::prelude::*; // Import QASM WASM support use pecos_qasm::QasmEngineWasm; -use pyo3::exceptions::PyTypeError; +use pyo3::exceptions::{PyRuntimeError, PyTypeError}; use pyo3::prelude::*; use std::sync::{Arc, Mutex}; @@ -21,6 +21,23 @@ use crate::engine_builders::{ }; use crate::wasm_foreign_object_bindings::PyWasmForeignObject; +fn unwrap_engine_builder_proxy(py: Python, engine_builder: Py) -> PyResult> { + match engine_builder + .bind(py) + .getattr(pyo3::intern!(py, "_builder")) + { + Ok(inner) => Ok(inner.into_any().unbind()), + Err(err) if err.is_instance_of::(py) => { + Ok(engine_builder) + } + Err(err) => Err(err), + } +} + +fn clone_py_any_option(py: Python, value: Option<&Py>) -> Option> { + value.map(|inner| inner.clone_ref(py)) +} + /// Check if a Python object is a Guppy function fn is_guppy_function(py: Python, obj: &Py) -> PyResult { // Check if guppylang module is available @@ -134,6 +151,7 @@ pub fn sim(py: Python, program: Py) -> PyResult { explicit_num_qubits: None, keep_intermediate_files: false, hugr_bytes: None, // QIS programs don't have HUGR bytes + operation_trace_dir: None, }), }) } else if let Ok(hugr_prog) = program.extract::(py) { @@ -220,6 +238,7 @@ impl PySimBuilder { #[allow(clippy::needless_pass_by_value)] // Py must be passed by value for PyO3 fn classical(&mut self, engine_builder: Py) -> PyResult { Python::attach(|py| { + let engine_builder = unwrap_engine_builder_proxy(py, engine_builder)?; match &mut self.inner { SimBuilderInner::Qasm(sim_builder) => { if let Ok(mut qasm_engine) = engine_builder.extract::(py) { @@ -276,9 +295,51 @@ impl PySimBuilder { Ok(PySimBuilder { inner: self.inner.clone(), }) + } else if let Ok(qis_engine) = engine_builder.extract::(py) + { + if sim_builder.foreign_object.is_some() { + return Err(PyTypeError::new_err( + "For HUGR programs, classical(QisEngineBuilder) is not compatible with foreign_object()", + )); + } + + let hugr_bytes = sim_builder.hugr_bytes.clone().ok_or_else(|| { + PyRuntimeError::new_err( + "HUGR program bytes are not available to switch this simulation onto the QIS/Helios path", + ) + })?; + let qis_engine = qis_engine + .inner + .clone() + .try_program(Hugr::from_bytes(hugr_bytes.clone())) + .map_err(|e| { + PyRuntimeError::new_err(format!( + "Failed to load HUGR program into QIS engine: {e}" + )) + })?; + + Ok(PySimBuilder { + inner: SimBuilderInner::QisControl(PyQisControlSimBuilder { + engine_builder: Arc::new(Mutex::new(Some(qis_engine))), + seed: sim_builder.seed, + workers: sim_builder.workers, + quantum_engine_builder: clone_py_any_option( + py, + sim_builder.quantum_engine_builder.as_ref(), + ), + noise_builder: clone_py_any_option( + py, + sim_builder.noise_builder.as_ref(), + ), + explicit_num_qubits: sim_builder.explicit_num_qubits, + keep_intermediate_files: sim_builder.keep_intermediate_files, + hugr_bytes: Some(hugr_bytes), + operation_trace_dir: None, + }), + }) } else { Err(PyTypeError::new_err( - "For direct HUGR programs, classical() requires a HugrEngineBuilder", + "For direct HUGR programs, classical() requires a HugrEngineBuilder or QisEngineBuilder", )) } } @@ -336,9 +397,7 @@ impl PySimBuilder { /// Use automatic worker count based on available CPUs fn auto_workers(&mut self) -> PyResult { - let workers = std::thread::available_parallelism() - .map(std::num::NonZero::get) - .unwrap_or(4); + let workers = std::thread::available_parallelism().map_or(4, std::num::NonZero::get); self.workers(workers) } @@ -464,6 +523,173 @@ impl PySimBuilder { }) } + /// Dump Helios-collected operation chunks to the given directory as JSON. + fn trace_operations(&mut self, trace_dir: &str) -> PyResult { + match &mut self.inner { + SimBuilderInner::QisControl(builder) => { + builder.operation_trace_dir = Some(trace_dir.to_string()); + } + SimBuilderInner::Qasm(_) + | SimBuilderInner::Hugr(_) + | SimBuilderInner::PhirJson(_) + | SimBuilderInner::Phir(_) + | SimBuilderInner::Empty => { + return Err(pyo3::exceptions::PyTypeError::new_err( + "trace_operations() is only supported for QIS control simulations", + )); + } + } + Ok(PySimBuilder { + inner: self.inner.clone(), + }) + } + + /// Capture one in-memory QIS operation trace shot and return it as Python data. + /// + /// This is the preferred programmatic tracing path for QIS-control simulations. + /// It collects the structured trace in memory first, and any JSON dumping + /// configured via `trace_operations(...)` becomes an optional mirror/export. + fn capture_operation_trace(&self, py: Python<'_>) -> PyResult> { + use crate::engine_builders::{ + PyBiasedDepolarizingNoiseModelBuilder, PyDepolarizingNoiseModelBuilder, + PyGeneralNoiseModelBuilder, + }; + use crate::engine_builders::{ + PyCoinTossEngineBuilder, PyDensityMatrixEngineBuilder, PySparseStabEngineBuilder, + PyStabVecEngineBuilder, PyStabilizerEngineBuilder, PyStateVectorEngineBuilder, + }; + + match &self.inner { + SimBuilderInner::QisControl(builder) => { + let mut builder_lock = builder.engine_builder.lock().expect("lock poisoned"); + let engine_builder = builder_lock + .take() + .ok_or_else(|| PyRuntimeError::new_err("Builder already consumed"))?; + let collector: pecos_qis::OperationTraceStore = Arc::new(Mutex::new(Vec::new())); + let engine_builder = + engine_builder.trace_operations_in_memory_to(collector.clone()); + let engine_builder = if let Some(ref trace_dir) = builder.operation_trace_dir { + engine_builder.trace_operations_to(trace_dir) + } else { + engine_builder + }; + + let mut sim_builder = pecos_engines::sim_builder().classical(engine_builder); + + if let Some(seed) = builder.seed { + sim_builder = sim_builder.seed(seed); + } + if let Some(workers) = builder.workers { + sim_builder = sim_builder.workers(workers); + } + let n = builder.explicit_num_qubits.ok_or_else(|| { + PyRuntimeError::new_err( + "QIS/HUGR programs require explicit qubit specification. \ + Please call .qubits(N) before capture_operation_trace().", + ) + })?; + sim_builder = sim_builder.qubits(n); + + if let Some(ref qe_py) = builder.quantum_engine_builder { + sim_builder = if let Ok(mut state_vec) = + qe_py.extract::(py) + { + if let Some(inner) = state_vec.inner.take() { + sim_builder.quantum(inner) + } else { + return Err(PyErr::new::( + "Quantum engine builder has already been consumed", + )); + } + } else if let Ok(mut sparse_stab) = + qe_py.extract::(py) + { + if let Some(inner) = sparse_stab.inner.take() { + sim_builder.quantum(inner) + } else { + return Err(PyErr::new::( + "Quantum engine builder has already been consumed", + )); + } + } else if let Ok(mut stab_vec) = qe_py.extract::(py) { + if let Some(inner) = stab_vec.inner.take() { + sim_builder.quantum(inner) + } else { + return Err(PyErr::new::( + "Quantum engine builder has already been consumed", + )); + } + } else if let Ok(mut density_mat) = + qe_py.extract::(py) + { + if let Some(inner) = density_mat.inner.take() { + sim_builder.quantum(inner) + } else { + return Err(PyErr::new::( + "Quantum engine builder has already been consumed", + )); + } + } else if let Ok(mut stab) = qe_py.extract::(py) { + if let Some(inner) = stab.inner.take() { + sim_builder.quantum(inner) + } else { + return Err(PyErr::new::( + "Quantum engine builder has already been consumed", + )); + } + } else if let Ok(mut ct) = qe_py.extract::(py) { + if let Some(inner) = ct.inner.take() { + sim_builder.quantum(inner) + } else { + return Err(PyErr::new::( + "Quantum engine builder has already been consumed", + )); + } + } else { + sim_builder + }; + } + + if let Some(ref noise_py) = builder.noise_builder { + sim_builder = + if let Ok(general) = noise_py.extract::(py) { + sim_builder.noise(general.inner.clone()) + } else if let Ok(depolarizing) = + noise_py.extract::(py) + { + sim_builder.noise(depolarizing.inner.clone()) + } else if let Ok(biased) = + noise_py.extract::(py) + { + sim_builder.noise(biased.inner.clone()) + } else { + sim_builder + }; + } + + sim_builder.run(1).map_err(|e| { + PyRuntimeError::new_err(format!("Trace capture simulation failed: {e}")) + })?; + + let trace = collector.lock().expect("lock poisoned").clone(); + let trace_json = serde_json::to_string(&trace).map_err(|e| { + PyRuntimeError::new_err(format!("Failed to serialize in-memory trace: {e}")) + })?; + let json = py.import(pyo3::intern!(py, "json"))?; + Ok(json + .call_method1(pyo3::intern!(py, "loads"), (trace_json,))? + .into()) + } + SimBuilderInner::Qasm(_) + | SimBuilderInner::Hugr(_) + | SimBuilderInner::PhirJson(_) + | SimBuilderInner::Phir(_) + | SimBuilderInner::Empty => Err(PyTypeError::new_err( + "capture_operation_trace() is only supported for QIS control simulations", + )), + } + } + /// Run the simulation #[allow(clippy::too_many_lines)] // Complex simulation dispatch with multiple engine types fn run(&self, shots: usize) -> PyResult { @@ -472,8 +698,8 @@ impl PySimBuilder { PyGeneralNoiseModelBuilder, }; use crate::engine_builders::{ - PyCliffordRzEngineBuilder, PyCoinTossEngineBuilder, PyDensityMatrixEngineBuilder, - PySparseStabEngineBuilder, PyStabilizerEngineBuilder, PyStateVectorEngineBuilder, + PyCoinTossEngineBuilder, PyDensityMatrixEngineBuilder, PySparseStabEngineBuilder, + PyStabVecEngineBuilder, PyStabilizerEngineBuilder, PyStateVectorEngineBuilder, }; use crate::shot_results_bindings::PyShotVec; use pyo3::exceptions::PyRuntimeError; @@ -537,10 +763,9 @@ impl PySimBuilder { "Quantum engine builder has already been consumed", )) } - } else if let Ok(mut clifford_rz) = - qe_py.extract::(py) + } else if let Ok(mut stab_vec) = qe_py.extract::(py) { - if let Some(inner) = clifford_rz.inner.take() { + if let Some(inner) = stab_vec.inner.take() { Ok(sim_builder.quantum(inner)) } else { Err(PyErr::new::( @@ -611,6 +836,11 @@ impl PySimBuilder { let engine_builder = builder_lock .take() .ok_or_else(|| PyRuntimeError::new_err("Builder already consumed"))?; + let engine_builder = if let Some(ref trace_dir) = builder.operation_trace_dir { + engine_builder.trace_operations_to(trace_dir) + } else { + engine_builder + }; // Use the Rust sim_builder API directly (from pecos prelude) let mut sim_builder = pecos_engines::sim_builder().classical(engine_builder); @@ -656,10 +886,9 @@ impl PySimBuilder { "Quantum engine builder has already been consumed", )) } - } else if let Ok(mut clifford_rz) = - qe_py.extract::(py) + } else if let Ok(mut stab_vec) = qe_py.extract::(py) { - if let Some(inner) = clifford_rz.inner.take() { + if let Some(inner) = stab_vec.inner.take() { Ok(sim_builder.quantum(inner)) } else { Err(PyErr::new::( @@ -824,10 +1053,9 @@ impl PySimBuilder { "Quantum engine builder has already been consumed", )) } - } else if let Ok(mut clifford_rz) = - qe_py.extract::(py) + } else if let Ok(mut stab_vec) = qe_py.extract::(py) { - if let Some(inner) = clifford_rz.inner.take() { + if let Some(inner) = stab_vec.inner.take() { Ok(sim_builder.quantum(inner)) } else { Err(PyErr::new::( @@ -905,8 +1133,8 @@ impl PySimBuilder { PyGeneralNoiseModelBuilder, }; use crate::engine_builders::{ - PyCliffordRzEngineBuilder, PyCoinTossEngineBuilder, PyDensityMatrixEngineBuilder, - PySparseStabEngineBuilder, PyStabilizerEngineBuilder, PyStateVectorEngineBuilder, + PyCoinTossEngineBuilder, PyDensityMatrixEngineBuilder, PySparseStabEngineBuilder, + PyStabVecEngineBuilder, PyStabilizerEngineBuilder, PyStateVectorEngineBuilder, }; use crate::engine_builders::{PyPhirJsonSimulation, PyPhirSimulation, PyQasmSimulation}; use pyo3::exceptions::PyRuntimeError; @@ -969,10 +1197,10 @@ impl PySimBuilder { "Quantum engine builder has already been consumed", )) } - } else if let Ok(mut clifford_rz) = - qe_py.extract::(py) + } else if let Ok(mut stab_vec) = + qe_py.extract::(py) { - if let Some(inner) = clifford_rz.inner.take() { + if let Some(inner) = stab_vec.inner.take() { Ok(sim_builder.quantum(inner)) } else { Err(PyErr::new::( @@ -1116,6 +1344,11 @@ impl PySimBuilder { let engine_builder = builder_lock .take() .ok_or_else(|| PyRuntimeError::new_err("Builder already consumed"))?; + let engine_builder = if let Some(ref trace_dir) = builder.operation_trace_dir { + engine_builder.trace_operations_to(trace_dir) + } else { + engine_builder + }; // Use the Rust sim_builder API directly (from pecos prelude) let mut sim_builder = pecos_engines::sim_builder().classical(engine_builder); @@ -1158,10 +1391,10 @@ impl PySimBuilder { "Quantum engine builder has already been consumed", )) } - } else if let Ok(mut clifford_rz) = - qe_py.extract::(py) + } else if let Ok(mut stab_vec) = + qe_py.extract::(py) { - if let Some(inner) = clifford_rz.inner.take() { + if let Some(inner) = stab_vec.inner.take() { Ok(sim_builder.quantum(inner)) } else { Err(PyErr::new::( @@ -1278,6 +1511,7 @@ impl PySimBuilder { crate::engine_builders::PyQisControlSimulation { inner: Arc::new(Mutex::new(engine)), temp_dir, + operation_trace_dir: builder.operation_trace_dir.clone(), }, )? .into_any()) @@ -1334,10 +1568,10 @@ impl PySimBuilder { "Quantum engine builder has already been consumed", )) } - } else if let Ok(mut clifford_rz) = - qe_py.extract::(py) + } else if let Ok(mut stab_vec) = + qe_py.extract::(py) { - if let Some(inner) = clifford_rz.inner.take() { + if let Some(inner) = stab_vec.inner.take() { Ok(sim_builder.quantum(inner)) } else { Err(PyErr::new::( @@ -1492,6 +1726,7 @@ impl Clone for SimBuilderInner { explicit_num_qubits: builder.explicit_num_qubits, keep_intermediate_files: builder.keep_intermediate_files, hugr_bytes: builder.hugr_bytes.clone(), + operation_trace_dir: builder.operation_trace_dir.clone(), }) } SimBuilderInner::PhirJson(builder) => SimBuilderInner::PhirJson(PyPhirJsonSimBuilder { diff --git a/python/pecos-rslib/src/simulators_module.rs b/python/pecos-rslib/src/simulators_module.rs index 6ac36d5b1..3752f6621 100644 --- a/python/pecos-rslib/src/simulators_module.rs +++ b/python/pecos-rslib/src/simulators_module.rs @@ -43,8 +43,8 @@ pub fn register_simulators_module(parent: &Bound<'_, PyModule>) -> PyResult<()> simulators.add("SparseStab", parent.getattr("SparseStab")?)?; simulators.add("Stabilizer", parent.getattr("Stabilizer")?)?; - // Clifford+RZ simulator - simulators.add("CliffordRz", parent.getattr("CliffordRz")?)?; + // StabVec simulator (Clifford+RZ) + simulators.add("StabVec", parent.getattr("StabVec")?)?; // State vector simulators simulators.add("StateVec", parent.getattr("StateVec")?)?; diff --git a/python/pecos-rslib/src/clifford_rz_bindings.rs b/python/pecos-rslib/src/stab_vec_bindings.rs similarity index 98% rename from python/pecos-rslib/src/clifford_rz_bindings.rs rename to python/pecos-rslib/src/stab_vec_bindings.rs index a8eab28d9..da54bca67 100644 --- a/python/pecos-rslib/src/clifford_rz_bindings.rs +++ b/python/pecos-rslib/src/stab_vec_bindings.rs @@ -12,18 +12,18 @@ use crate::dtypes::AngleParam; use crate::prelude::*; -use pecos_simulators::CliffordRz; +use pecos_simulators::StabVec; use pyo3::IntoPyObjectExt; use pyo3::prelude::*; use pyo3::types::{PyAny, PyDict, PyList, PySet, PyTuple}; -#[pyclass(name = "CliffordRz", module = "pecos_rslib")] -pub struct PyCliffordRz { - inner: CliffordRz, +#[pyclass(name = "StabVec", module = "pecos_rslib")] +pub struct PyStabVec { + inner: StabVec, } #[pymethods] -impl PyCliffordRz { +impl PyStabVec { /// Create a new Clifford+RZ simulator. /// /// Args: @@ -40,7 +40,7 @@ impl PyCliffordRz { pruning_threshold: Option, mc_threshold: Option, ) -> Self { - let mut builder = CliffordRz::builder(num_qubits); + let mut builder = StabVec::builder(num_qubits); if let Some(s) = seed { builder = builder.seed(s); } @@ -48,7 +48,7 @@ impl PyCliffordRz { builder = builder.pruning_threshold(pt); } builder = builder.mc_threshold(mc_threshold); - PyCliffordRz { + PyStabVec { inner: builder.build(), } } diff --git a/python/quantum-pecos/pyproject.toml b/python/quantum-pecos/pyproject.toml index 6ea7bf116..1d22357c1 100644 --- a/python/quantum-pecos/pyproject.toml +++ b/python/quantum-pecos/pyproject.toml @@ -59,7 +59,7 @@ repository = "https://github.com/PECOS-packages/PECOS" [project.optional-dependencies] stim = [ - "stim>=1.12.0", # For Stim circuit conversion and interoperability + "stim>=1.15.0", # For Stim circuit conversion and interoperability ] visualization = [ "matplotlib>=2.2.0", @@ -99,3 +99,8 @@ packages = ["src/pecos"] [tool.black] line-length = 120 + +[tool.pytest.ini_options] +markers = [ + "slow: mark tests that provide extra integration coverage but are excluded from the default fast Python test lane", +] diff --git a/python/quantum-pecos/src/pecos/__init__.py b/python/quantum-pecos/src/pecos/__init__.py index e93d2a8a5..af1bc5e6e 100644 --- a/python/quantum-pecos/src/pecos/__init__.py +++ b/python/quantum-pecos/src/pecos/__init__.py @@ -47,6 +47,9 @@ ShotVec, # Simulation result: vector of shots TimeUnits, # Abstract time duration in arbitrary units WasmForeignObject, # WASM foreign object for classical coprocessor + X, # Single-qubit Pauli X constructor: X(qubit) -> PauliString + Y, # Single-qubit Pauli Y constructor: Y(qubit) -> PauliString + Z, # Single-qubit Pauli Z constructor: Z(qubit) -> PauliString abs, # Absolute value acos, # Inverse cosine acosh, # Inverse hyperbolic cosine @@ -256,6 +259,7 @@ def __getattr__(name: str): phir_json_engine, qasm_engine, qis_engine, + selene_engine, ) # Simulation entry point @@ -282,7 +286,7 @@ def __getattr__(name: str): state_vector = pecos_rslib.state_vector sparse_stab = pecos_rslib.sparse_stab stabilizer = pecos_rslib.stabilizer -clifford_rz = pecos_rslib.clifford_rz +stab_vec = pecos_rslib.stab_vec density_matrix = pecos_rslib.density_matrix hugr_engine = pecos_rslib.hugr_engine @@ -299,33 +303,27 @@ def __getattr__(name: str): "SIGNED_INTEGER_TYPES", "UNSIGNED_INTEGER_TYPES", "AngleSource", - # Core types "Array", - # Deprecated "BiasedDepolarizingNoiseModelBuilder", - "BinArray", # Deprecated - use BitInt instead + "BinArray", "BitInt", "BitUInt", - # Type categories "Complex", "DepolarizingNoiseModelBuilder", "Float", "GateRegistry", "GateSignatureMismatchError", "GeneralNoiseModelBuilder", - # Program wrapper classes for sim() - also available via pecos.programs "Guppy", "Hugr", - # Legacy "HybridEngine", "Inexact", "Integer", - "Nanoseconds", # Time unit type + "Nanoseconds", "Numeric", "Pauli", "PauliString", "PhirJson", - # Engine builder classes "PhirJsonEngineBuilder", "Poly1d", "ProgramWrapper", @@ -337,26 +335,24 @@ def __getattr__(name: str): "ShotMap", "ShotVec", "SignedInteger", - "TimeUnits", # Time unit type + "TimeUnits", "UnsignedInteger", "Wasm", "WasmError", "WasmForeignObject", "Wat", - # Version + "X", + "Y", + "Z", "__version__", - # Mathematical functions "abs", "acos", "acosh", "all", "allclose", - # Subpackages - "analysis", # QEC analysis (threshold, fault tolerance, stabilizers) - # Angle type + "analysis", "angle64", "any", - # Polynomial and optimization "arange", "array", "array_equal", @@ -365,18 +361,13 @@ def __getattr__(name: str): "atan", "atan2", "atanh", - "benchmarks", # Performance benchmarking - # Noise model builders + "benchmarks", "biased_depolarizing_noise", "brentq", "ceil", - # Subpackages - Utilities "circuit_converters", "circuit_runners", - # Subpackages - Core "circuits", - "clifford_rz", - # Numeric submodules (like numpy.linalg, numpy.random) "compare", "complex64", "complex128", @@ -388,10 +379,9 @@ def __getattr__(name: str): "density_matrix", "depolarizing_noise", "diag", - # Data types "dtypes", "engines", - "exceptions", # Exception classes + "exceptions", "exp", "f32", "f64", @@ -399,7 +389,7 @@ def __getattr__(name: str): "general_noise", "get_guppy_backends", "graph", - "guppy", # Direct Guppy code generation + "guppy", "hugr_engine", "i8", "i16", @@ -423,7 +413,6 @@ def __getattr__(name: str): "num", "ones", "optimize", - # Engine builder functions "phir_json_engine", "polyfit", "polynomial", @@ -431,20 +420,20 @@ def __getattr__(name: str): "programs", "protocols", "qasm_engine", - "qec", # Pure QEC geometry (no SLR dependencies) + "qec", "qeccs", "qis_engine", "quantum", "random", "round", - # Simulation entry point + "selene_engine", "sim", "simulators", "sin", "sinh", - # Quantum simulators "sparse_stab", "sqrt", + "stab_vec", "stabilizer", "state_vector", "stats", @@ -452,8 +441,8 @@ def __getattr__(name: str): "sum", "tan", "tanh", - "testing", # Testing utilities (like numpy.testing) - "tools", # Kept for backwards compatibility + "testing", + "tools", "typing", "u8", "u16", diff --git a/python/quantum-pecos/src/pecos/_engine_builders.py b/python/quantum-pecos/src/pecos/_engine_builders.py index 12ed7d252..f8f1e3047 100644 --- a/python/quantum-pecos/src/pecos/_engine_builders.py +++ b/python/quantum-pecos/src/pecos/_engine_builders.py @@ -155,12 +155,22 @@ def program(self, program: Qis | Hugr | CompiledQis) -> Self: self._builder = self._builder.program(program) return self - def selene_runtime(self) -> Self: + def selene_runtime(self, runtime_name: str | None = None) -> Self: """Use Selene simple runtime. + Args: + runtime_name: Optional runtime name. ``None`` and + ``"selene_simple_runtime"`` both select the default runtime. + Returns: Self for method chaining. """ + if runtime_name not in (None, "selene_simple_runtime"): + msg = ( + "Python QisEngineBuilder.selene_runtime(runtime_name=...) only " + "supports the default 'selene_simple_runtime' wrapper today." + ) + raise NotImplementedError(msg) self._builder = self._builder.selene_runtime() return self @@ -221,6 +231,25 @@ def qis_engine() -> QisEngineBuilder: return QisEngineBuilder() +def selene_engine(runtime_name: str | None = None) -> QisEngineBuilder: + """Create a Selene-backed QIS engine builder. + + Args: + runtime_name: Optional built Selene runtime library name. + When omitted, the default simple Selene runtime is used. + + Returns: + QisEngineBuilder: A builder for Selene-backed QIS/HUGR simulations. + """ + if runtime_name not in (None, "selene_simple_runtime"): + msg = ( + "Python selene_engine(runtime_name=...) is not currently supported by the wrapper. " + "Use the default runtime or call into pecos_rslib directly for custom runtime names." + ) + raise NotImplementedError(msg) + return QisEngineBuilder().selene_runtime().interface(pecos_rslib.qis_helios_interface()) + + __all__ = [ # Builder classes "PhirJsonEngineBuilder", @@ -230,4 +259,5 @@ def qis_engine() -> QisEngineBuilder: "phir_json_engine", "qasm_engine", "qis_engine", + "selene_engine", ] diff --git a/python/quantum-pecos/src/pecos/engines/__init__.py b/python/quantum-pecos/src/pecos/engines/__init__.py index dc20b1a21..1299c30cb 100644 --- a/python/quantum-pecos/src/pecos/engines/__init__.py +++ b/python/quantum-pecos/src/pecos/engines/__init__.py @@ -53,7 +53,6 @@ get_compilation_backends, qis_helios_interface, qis_selene_helios_interface, - selene_runtime, sim_builder, ) from pecos_rslib.engines import ( @@ -104,6 +103,5 @@ "qis_engine", "qis_helios_interface", "qis_selene_helios_interface", - "selene_runtime", "sim_builder", ] diff --git a/python/quantum-pecos/src/pecos/guppy/surface.py b/python/quantum-pecos/src/pecos/guppy/surface.py index 7d11e01fc..66883176e 100644 --- a/python/quantum-pecos/src/pecos/guppy/surface.py +++ b/python/quantum-pecos/src/pecos/guppy/surface.py @@ -159,10 +159,25 @@ def generate_guppy_source(patch: "SurfacePatch") -> str: lines.extend(f" h(ax{stab.index})" for stab in geom.x_stabilizers) # Measure ancillas (destructive) + # Each measurement gets a per-measurement result() call that ties the + # physical measurement to a MeasId. The result() names encode the + # stabilizer type and index. The AllocateResult IDs generated by + # these calls flow through the trace and become MeasIds on the TickCircuit. lines.append("") + # Measure ancillas with per-measurement result() identity. + # Tag format: "label:idx" where label is the stabilizer name and idx is the + # round-local measurement index. The global MeasId is assigned by the runtime + # via AllocateResult and flows through the trace automatically. lines.append(" # Measure ancillas") - lines.extend(f" sx{stab.index} = measure(ax{stab.index})" for stab in geom.x_stabilizers) - lines.extend(f" sz{stab.index} = measure(az{stab.index})" for stab in geom.z_stabilizers) + idx = 0 + for stab in geom.x_stabilizers: + lines.append(f" sx{stab.index} = measure(ax{stab.index})") + lines.append(f' result("sx{stab.index}:meas:{idx}", sx{stab.index})') + idx += 1 + for stab in geom.z_stabilizers: + lines.append(f" sz{stab.index} = measure(az{stab.index})") + lines.append(f' result("sz{stab.index}:meas:{idx}", sz{stab.index})') + idx += 1 x_calls = ", ".join(f"sx{s.index}" for s in geom.x_stabilizers) z_calls = ", ".join(f"sz{s.index}" for s in geom.z_stabilizers) diff --git a/python/quantum-pecos/src/pecos/noise/depolarizing_error_model.py b/python/quantum-pecos/src/pecos/noise/depolarizing_error_model.py index 9e15a7cb0..9f1c21a0c 100644 --- a/python/quantum-pecos/src/pecos/noise/depolarizing_error_model.py +++ b/python/quantum-pecos/src/pecos/noise/depolarizing_error_model.py @@ -72,7 +72,7 @@ def __init__(self, error_params: dict) -> None: - p1: Single-qubit gate error probability - p2: Two-qubit gate error probability - p_meas: Measurement error probability - - p_init: Initialization error probability + - p_prep: Preparation error probability - scale: Optional scaling factor for all error rates - p1_error_model: Optional custom single-qubit Pauli error distribution - p2_error_model: Optional custom two-qubit Pauli error distribution @@ -125,7 +125,7 @@ def _scale(self) -> None: self._eparams["p_meas"] = pc.mean(self._eparams["p_meas"]) self._eparams["p_meas"] *= scale - self._eparams["p_init"] *= scale + self._eparams["p_prep"] *= scale def shot_reinit(self) -> None: """Run all code needed at the beginning of each shot, e.g., resetting state.""" @@ -159,7 +159,7 @@ def process( elif op.name in {"init |0>", "Init", "Init +Z"}: qops_after = noise_initz_bitflip( op, - p=self._eparams["p_init"], + p=self._eparams["p_prep"], ) # ######################################## diff --git a/python/quantum-pecos/src/pecos/noise/error_depolar.py b/python/quantum-pecos/src/pecos/noise/error_depolar.py index 5d0683db7..b723b9649 100644 --- a/python/quantum-pecos/src/pecos/noise/error_depolar.py +++ b/python/quantum-pecos/src/pecos/noise/error_depolar.py @@ -72,7 +72,7 @@ def scaling(self) -> None: self.error_params["p_meas"] = pc.mean(self.error_params["p_meas"]) self.error_params["p_meas"] *= scale - self.error_params["p_init"] *= scale + self.error_params["p_prep"] *= scale def start( self, @@ -152,7 +152,7 @@ def generate_tick_errors( # INITS WITH X NOISE elif symbol == "init |0>": noisy = set(locations) - self.error_params["noiseless_qubits"] - noise_init_bitflip(noisy, after, "X", p=self.error_params["p_init"]) + noise_init_bitflip(noisy, after, "X", p=self.error_params["p_prep"]) # ######################################## # ONE QUBIT GATES diff --git a/python/quantum-pecos/src/pecos/noise/generic_error_model.py b/python/quantum-pecos/src/pecos/noise/generic_error_model.py index a2ebaaf77..0d892db99 100644 --- a/python/quantum-pecos/src/pecos/noise/generic_error_model.py +++ b/python/quantum-pecos/src/pecos/noise/generic_error_model.py @@ -80,7 +80,7 @@ def __init__(self, error_params: dict) -> None: - p1: Single-qubit gate error probability - p2: Two-qubit gate error probability - p_meas: Measurement error probability - - p_init: Initialization error probability + - p_prep: Preparation error probability - scale: Optional scaling factor for all error rates - p1_error_model: Optional custom single-qubit Pauli error distribution - p2_error_model: Optional custom two-qubit Pauli error distribution @@ -134,7 +134,7 @@ def _scale(self) -> None: self._eparams["p_meas"] = pc.mean(self._eparams["p_meas"]) self._eparams["p_meas"] *= scale - self._eparams["p_init"] *= scale + self._eparams["p_prep"] *= scale def shot_reinit(self) -> None: """Run all code needed at the beginning of each shot, e.g., resetting state.""" @@ -165,7 +165,7 @@ def process( if op.name in {"init |0>", "Init", "Init +Z"}: qops_after = noise_initz_bitflip_leakage( op, - p=self._eparams["p_init"], + p=self._eparams["p_prep"], machine=self.machine, ) diff --git a/python/quantum-pecos/src/pecos/noise/simple_depolarizing_error_model.py b/python/quantum-pecos/src/pecos/noise/simple_depolarizing_error_model.py index a739f8822..4569c4677 100644 --- a/python/quantum-pecos/src/pecos/noise/simple_depolarizing_error_model.py +++ b/python/quantum-pecos/src/pecos/noise/simple_depolarizing_error_model.py @@ -62,7 +62,7 @@ def __init__(self, error_params: dict) -> None: - p1: Single-qubit gate error probability - p2: Two-qubit gate error probability - p_meas: Measurement error probability - - p_init: Initialization error probability + - p_prep: Initialization error probability """ self.error_params = dict(error_params) self.machine = None @@ -127,7 +127,7 @@ def process( # Use fused operation to check and get error indices in one pass error_indices = pc.random.compare_indices( len(op.args), - self._eparams["p_init"], + self._eparams["p_prep"], ) for idx in error_indices: diff --git a/python/quantum-pecos/src/pecos/qec/__init__.py b/python/quantum-pecos/src/pecos/qec/__init__.py index 3288d2966..de5fe5142 100644 --- a/python/quantum-pecos/src/pecos/qec/__init__.py +++ b/python/quantum-pecos/src/pecos/qec/__init__.py @@ -38,9 +38,6 @@ EquivalenceResult, FaultLocation, InfluenceBuilder, - MeasurementNoiseModel, - MemBuilder, - NoisySampler, ParsedDem, assert_dems_equivalent, compare_dems_exact, @@ -50,6 +47,15 @@ from pecos.qec import analysis, color, protocols, surface from pecos.qec.analysis import ( + build_adaptive_dem, + compare_flip_matrices, + compare_k_body_rates, + detector_flip_matrices_by_round, + detector_flip_matrix, + detector_k_body_rates, + detector_k_body_rates_by_round, + empirical_correlation_table, + fit_dem_from_simulation, logical_error_rate, logical_fidelity, logical_from_data, @@ -110,9 +116,6 @@ "EquivalenceResult", "FaultLocation", "InfluenceBuilder", - "MeasurementNoiseModel", - "MemBuilder", - "NoisySampler", "ParsedDem", "assert_dems_equivalent", "compare_dems_exact", @@ -124,6 +127,15 @@ "PAULI_Y", "PAULI_Z", # Analysis utilities + "build_adaptive_dem", + "compare_flip_matrices", + "compare_k_body_rates", + "detector_flip_matrices_by_round", + "detector_flip_matrix", + "detector_k_body_rates", + "detector_k_body_rates_by_round", + "empirical_correlation_table", + "fit_dem_from_simulation", "logical_error_rate", "logical_fidelity", "logical_from_data", diff --git a/python/quantum-pecos/src/pecos/qec/analysis.py b/python/quantum-pecos/src/pecos/qec/analysis.py index b2121afa6..ca6007734 100644 --- a/python/quantum-pecos/src/pecos/qec/analysis.py +++ b/python/quantum-pecos/src/pecos/qec/analysis.py @@ -216,3 +216,687 @@ def lower_bound_fidelity(f1: float, f2: float) -> float: Lower bound on true fidelity. """ return (4 / 5) * (f1 + f2) - (3 / 5) + + +# --------------------------------------------------------------------------- +# Detector flip frequency matrices +# --------------------------------------------------------------------------- + + +def detector_flip_matrix( + detector_events: Sequence[Sequence[int]], + num_detectors: int, +) -> list[list[float]]: + """Compute the detector flip frequency matrix from sampled detector events. + + The matrix M has: + - M[i][i] = P(detector i fires) (marginal rate) + - M[i][j] = 0.5 * P(detector i AND j both fire) (half joint rate) + + The factor 0.5 on off-diagonal entries makes the matrix interpretable + as a covariance-like object: each correlated error mechanism contributes + equally to M[i][j] and M[j][i]. + + Args: + detector_events: Per-shot detector outcomes. Each entry is a sequence + of detector indices that fired in that shot. Alternatively, each + entry can be a full-length binary vector (0/1) of length + ``num_detectors``. + num_detectors: Total number of detectors. + + Returns: + ``num_detectors x num_detectors`` matrix as nested lists. + """ + n = num_detectors + shots = len(detector_events) + if shots == 0: + return [[0.0] * n for _ in range(n)] + + inv_shots = 1.0 / shots + half_inv = 0.5 * inv_shots + + # Accumulate as flat list for speed + m = [0.0] * (n * n) + + for events in detector_events: + # Determine which detectors fired + if len(events) == n: + # Full binary vector + fired = [i for i in range(n) if events[i]] + else: + # Sparse list of detector indices + fired = list(events) + + for a in fired: + m[a * n + a] += inv_shots # diagonal + for b in fired: + if b > a: + m[a * n + b] += half_inv + m[b * n + a] += half_inv + + return [m[i * n : (i + 1) * n] for i in range(n)] + + +def detector_flip_matrices_by_round( + detector_events: Sequence[Sequence[int]], + num_detectors: int, + detectors_per_round: int, +) -> list[list[list[float]]]: + """Compute per-round detector flip frequency matrices. + + Groups detectors into rounds of ``detectors_per_round`` each and + computes a separate flip frequency matrix for each round. + + Args: + detector_events: Per-shot detector outcomes (same format as + :func:`detector_flip_matrix`). + num_detectors: Total number of detectors. + detectors_per_round: Number of detectors in each syndrome + extraction round. + + Returns: + List of matrices, one per round. + """ + num_rounds = (num_detectors + detectors_per_round - 1) // detectors_per_round + shots = len(detector_events) + if shots == 0: + return [ + [[0.0] * detectors_per_round for _ in range(detectors_per_round)] + for _ in range(num_rounds) + ] + + inv_shots = 1.0 / shots + half_inv = 0.5 * inv_shots + k = detectors_per_round + + # One flat matrix per round + matrices = [[0.0] * (k * k) for _ in range(num_rounds)] + + for events in detector_events: + if len(events) == num_detectors: + fired = [i for i in range(num_detectors) if events[i]] + else: + fired = list(events) + + # Bin by round + round_fired: dict[int, list[int]] = {} + for d in fired: + r = d // k + local = d % k + round_fired.setdefault(r, []).append(local) + + for r, local_ids in round_fired.items(): + if r >= num_rounds: + continue + mat = matrices[r] + for a in local_ids: + mat[a * k + a] += inv_shots + for b in local_ids: + if b > a: + mat[a * k + b] += half_inv + mat[b * k + a] += half_inv + + return [ + [matrices[r][i * k : (i + 1) * k] for i in range(k)] + for r in range(num_rounds) + ] + + +def compare_flip_matrices( + sim_matrix: Sequence[Sequence[float]], + dem_matrix: Sequence[Sequence[float]], + *, + min_rate: float = 0.0005, +) -> tuple[float, float, tuple[int, int]]: + """Compare two detector flip frequency matrices. + + Args: + sim_matrix: Ground truth matrix (from simulation). + dem_matrix: Test matrix (from DEM sampling). + min_rate: Minimum entry value to consider (avoids division by tiny + numbers from statistical noise). + + Returns: + Tuple of ``(max_relative_error, frobenius_relative_error, + worst_element)`` where ``worst_element`` is the ``(i, j)`` index + of the largest relative error. + """ + n = len(sim_matrix) + max_err = 0.0 + worst = (0, 0) + sum_sq_diff = 0.0 + sum_sq_sim = 0.0 + + for i in range(n): + for j in range(n): + s = sim_matrix[i][j] + d = dem_matrix[i][j] + diff = d - s + sum_sq_diff += diff * diff + sum_sq_sim += s * s + if s > min_rate: + rel = abs(diff / s) + if rel > max_err: + max_err = rel + worst = (i, j) + + frob_rel = (sum_sq_diff**0.5) / max(sum_sq_sim**0.5, 1e-30) + return max_err, frob_rel, worst + + +# --------------------------------------------------------------------------- +# Higher-order detector correlation analysis +# --------------------------------------------------------------------------- + + +def detector_k_body_rates( + detector_events: Sequence[Sequence[int]], + num_detectors: int, + max_order: int = 3, +) -> dict[tuple[int, ...], float]: + """Compute k-body detector firing rates up to a given order. + + For each subset of detectors of size 1..max_order that fires together + in at least one shot, records the joint firing probability. + + - 1-body: ``(i,)`` -> P(Di fires) + - 2-body: ``(i, j)`` -> P(Di AND Dj fire) + - 3-body: ``(i, j, k)`` -> P(Di AND Dj AND Dk fire) + + Keys are sorted tuples of detector indices. + + Args: + detector_events: Per-shot detector outcomes. Each entry is either + a list of fired detector indices or a full binary vector. + num_detectors: Total number of detectors. + max_order: Maximum correlation order (default 3). + + Returns: + Dict mapping detector index tuples to joint firing rates. + """ + from itertools import combinations + + shots = len(detector_events) + if shots == 0: + return {} + + inv_shots = 1.0 / shots + rates: dict[tuple[int, ...], float] = {} + + for events in detector_events: + if len(events) == num_detectors: + fired = [i for i in range(num_detectors) if events[i]] + else: + fired = sorted(events) + + for k in range(1, min(max_order, len(fired)) + 1): + for combo in combinations(fired, k): + if combo in rates: + rates[combo] += inv_shots + else: + rates[combo] = inv_shots + + return rates + + +def detector_k_body_rates_by_round( + detector_events: Sequence[Sequence[int]], + num_detectors: int, + detectors_per_round: int, + max_order: int = 3, +) -> list[dict[tuple[int, ...], float]]: + """Compute per-round k-body detector firing rates. + + Groups detectors into rounds, then computes k-body rates within + each round. Detector indices in the returned dicts are round-local + (0..detectors_per_round-1). + + Args: + detector_events: Per-shot detector outcomes. + num_detectors: Total number of detectors. + detectors_per_round: Number of detectors per round. + max_order: Maximum correlation order (default 3). + + Returns: + List of dicts, one per round, mapping local detector index + tuples to joint firing rates. + """ + from itertools import combinations + + k = detectors_per_round + num_rounds = (num_detectors + k - 1) // k + shots = len(detector_events) + if shots == 0: + return [{} for _ in range(num_rounds)] + + inv_shots = 1.0 / shots + round_rates: list[dict[tuple[int, ...], float]] = [{} for _ in range(num_rounds)] + + for events in detector_events: + if len(events) == num_detectors: + fired = [i for i in range(num_detectors) if events[i]] + else: + fired = sorted(events) + + # Bin fired detectors by round + round_fired: dict[int, list[int]] = {} + for d in fired: + r = d // k + local = d % k + round_fired.setdefault(r, []).append(local) + + for r, local_ids in round_fired.items(): + if r >= num_rounds: + continue + rr = round_rates[r] + for order in range(1, min(max_order, len(local_ids)) + 1): + for combo in combinations(local_ids, order): + if combo in rr: + rr[combo] += inv_shots + else: + rr[combo] = inv_shots + + return round_rates + + +def compare_k_body_rates( + sim_rates: dict[tuple[int, ...], float], + dem_rates: dict[tuple[int, ...], float], + *, + min_rate: float = 0.0005, + max_order: int | None = None, +) -> dict[int, tuple[float, float, tuple[int, ...]]]: + """Compare k-body rates between simulation and DEM, grouped by order. + + Args: + sim_rates: Ground truth rates from simulation. + dem_rates: Rates from DEM sampling. + min_rate: Minimum rate to consider for relative error. + max_order: If set, only compare up to this order. + + Returns: + Dict mapping order k to ``(max_relative_error, + rms_relative_error, worst_event)`` for that order. + """ + # Collect all keys + all_keys = set(sim_rates.keys()) | set(dem_rates.keys()) + + # Group by order + by_order: dict[int, list[tuple[tuple[int, ...], float, float]]] = {} + for key in all_keys: + k = len(key) + if max_order is not None and k > max_order: + continue + s = sim_rates.get(key, 0.0) + d = dem_rates.get(key, 0.0) + by_order.setdefault(k, []).append((key, s, d)) + + result: dict[int, tuple[float, float, tuple[int, ...]]] = {} + for k in sorted(by_order.keys()): + entries = by_order[k] + max_err = 0.0 + worst: tuple[int, ...] = () + sum_sq_rel = 0.0 + count = 0 + + for key, s, d in entries: + if s > min_rate: + rel = abs(d / s - 1) + if rel > max_err: + max_err = rel + worst = key + sum_sq_rel += rel * rel + count += 1 + + rms = (sum_sq_rel / max(count, 1)) ** 0.5 + result[k] = (max_err, rms, worst) + + return result + + +# --------------------------------------------------------------------------- +# Simulation-based correlation table +# --------------------------------------------------------------------------- + + +def empirical_correlation_table( + tick_circuit: object, + noise_builder: object, + shots: int, + max_order: int = 2, + *, + backend: str = "stabilizer", + seed: int = 42, +) -> list[tuple[tuple[int, ...], float]]: + """Build an empirical correlation table from simulation. + + Runs ``sim_neo`` with the given noise model, extracts detector events + per shot, and computes k-body joint detection rates. Same output format + as :func:`exact_correlation_table` from the Heisenberg walk. + + Args: + tick_circuit: A ``TickCircuit`` with detector metadata. + noise_builder: A noise builder (e.g., ``depolarizing().p1(0.001).p2(0.01)``). + shots: Number of simulation shots. + max_order: Maximum correlation order (1 = marginals, 2 = pairwise, etc.). + backend: Simulator backend — ``"stabilizer"``, ``"statevec"``, + ``"dem_sampling"``, or ``"meas_sampling"``. The DEM sampling + backend uses the fast whole-circuit DEM-based sampler + (geometric/O(fired)) instead of gate-by-gate simulation. + seed: RNG seed. + + Returns: + List of ``(detector_indices_tuple, probability)`` pairs, same format + as ``exact_correlation_table``. + + Example:: + + from pecos_rslib_exp import depolarizing + from pecos.qec.analysis import empirical_correlation_table + + table = empirical_correlation_table( + tc, depolarizing().p1(0.001).p2(0.01), shots=100000, max_order=3, + ) + for indices, prob in table: + print(f"P({indices}) = {prob:.6f}") + """ + import json + + from pecos_rslib_exp import ( + dem_sampling, + meas_sampling, + sim_neo, + stabilizer, + statevec, + ) + + if backend in ("dem_sampling", "meas_sampling"): + sampling_backend = dem_sampling() if backend == "dem_sampling" else meas_sampling() + results = ( + sim_neo(tick_circuit) + .quantum(sampling_backend) + .noise(noise_builder) + .shots(shots) + .seed(seed) + .run() + ) + elif backend in ("stabilizer", "statevec"): + backend_obj = stabilizer() if backend == "stabilizer" else statevec() + results = ( + sim_neo(tick_circuit) + .quantum(backend_obj) + .noise(noise_builder) + .shots(shots) + .seed(seed) + .run() + ) + else: + supported = "'stabilizer', 'statevec', 'dem_sampling', 'meas_sampling'" + raise ValueError( + f"Unknown backend {backend!r}. Supported: {supported}." + ) + + det_json = json.loads(tick_circuit.get_meta("detectors")) + obs_json_str = tick_circuit.get_meta("observables") + obs_json = json.loads(obs_json_str) if obs_json_str else [] + num_meas = int(tick_circuit.get_meta("num_measurements")) + num_dets = len(det_json) + + # Extract fired detectors and observables per shot + fired_per_shot: list[list[int]] = [] + obs_per_shot: list[list[int]] = [] + for r in results: + meas = list(r) + fired: list[int] = [] + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + fired.append(i) + fired_per_shot.append(fired) + + obs_fired: list[int] = [] + for i, obs in enumerate(obs_json): + val = 0 + for rec in obs["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + obs_fired.append(i) + obs_per_shot.append(obs_fired) + + # Compute detector k-body rates with string labels + from itertools import combinations + + inv_shots = 1.0 / shots + rates: dict[tuple[str, ...], float] = {} + + for fired in fired_per_shot: + labels = [f"D{d}" for d in fired] + for k in range(1, min(max_order, len(labels)) + 1): + for combo in combinations(labels, k): + rates[combo] = rates.get(combo, 0.0) + inv_shots + + # Observable marginals: P(Lj) + for obs_fired in obs_per_shot: + for o in obs_fired: + key = (f"L{o}",) + rates[key] = rates.get(key, 0.0) + inv_shots + + # Detector-observable pairwise: P(Di AND Lj) + for fired, obs_fired in zip(fired_per_shot, obs_per_shot): + for d in fired: + for o in obs_fired: + key = (f"D{d}", f"L{o}") + rates[key] = rates.get(key, 0.0) + inv_shots + + return sorted(rates.items()) + + +def fit_dem_from_simulation( + tick_circuit: object, + noise_builder: object, + shots: int, + *, + backend: str = "stabilizer", + seed: int = 42, + max_correlation_order: int = 2, +) -> str: + """Build a DEM fitted to simulation data. + + Runs simulation to get empirical detection rates, uses the circuit's + mechanism structure, and fits mechanism probabilities to match the + empirical marginals and pairwise rates. Returns a Stim DEM string. + + This is the "hardware calibration" workflow: real noise statistics + (or accurate simulation) combined with circuit-derived structure. + + Args: + tick_circuit: A ``TickCircuit`` with detector metadata. + noise_builder: A noise builder (e.g., ``depolarizing().p1(0.001)``). + shots: Number of simulation shots. + backend: Simulator backend — ``"stabilizer"``, ``"statevec"``, + ``"dem_sampling"``, or ``"meas_sampling"``. The DEM sampling + backend uses the fast whole-circuit DEM-based sampler instead of + gate-by-gate simulation. + seed: RNG seed. + max_correlation_order: Max order for empirical rates (1 or 2). + + Returns: + Stim-format DEM string with simulation-fitted probabilities. + """ + import json + from itertools import combinations + + from pecos_rslib.qec import ( + DemBuilder, + DagFaultAnalyzer, + fit_dem_to_marginals, + mechanisms_to_dem_string, + ) + from pecos_rslib_exp import ( + dem_sampling, + meas_sampling, + sim_neo, + stabilizer, + statevec, + ) + + # Step 1: Get mechanism structure from circuit + dag = tick_circuit.to_dag_circuit() + analyzer = DagFaultAnalyzer(dag) + influence = analyzer.build_influence_map() + # Use dummy noise to get mechanism structure (probabilities will be replaced) + builder = DemBuilder(influence) + builder = builder.with_noise(p1=0.01, p2=0.01, p_meas=0.01, p_prep=0.01) + builder = builder.with_detectors_json(tick_circuit.get_meta("detectors")) + builder = builder.with_observables_json(tick_circuit.get_meta("observables")) + builder = builder.with_num_measurements( + int(tick_circuit.get_meta("num_measurements")) + ) + dem = builder.build() + dem_str = dem.to_string() + + mechs: list[tuple[float, list[int], list[int]]] = [] + for line in dem_str.strip().split("\n"): + line = line.strip() + if line.startswith("error("): + pe = line.index(")") + prob = float(line[6:pe]) + toks = line[pe + 1 :].split() + ds = sorted(int(t[1:]) for t in toks if t.startswith("D")) + os = sorted(int(t[1:]) for t in toks if t.startswith("L")) + mechs.append((prob, ds, os)) + + # Step 2: Run simulation and extract empirical rates + det_json = json.loads(tick_circuit.get_meta("detectors")) + num_meas = int(tick_circuit.get_meta("num_measurements")) + num_dets = len(det_json) + + if backend in ("dem_sampling", "meas_sampling"): + sampling_backend = dem_sampling() if backend == "dem_sampling" else meas_sampling() + results = ( + sim_neo(tick_circuit) + .quantum(sampling_backend) + .noise(noise_builder) + .shots(shots) + .seed(seed) + .run() + ) + elif backend in ("stabilizer", "statevec"): + backend_obj = stabilizer() if backend == "stabilizer" else statevec() + results = ( + sim_neo(tick_circuit) + .quantum(backend_obj) + .noise(noise_builder) + .shots(shots) + .seed(seed) + .run() + ) + else: + supported = "'stabilizer', 'statevec', 'dem_sampling', 'meas_sampling'" + raise ValueError(f"Unknown backend {backend!r}. Supported: {supported}.") + + inv_shots = 1.0 / shots + emp_marginals = [0.0] * num_dets + for r in results: + meas = list(r) + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(meas): + val ^= meas[idx] + if val: + emp_marginals[i] += inv_shots + + # Step 3: Fit mechanism probabilities to empirical marginals + fitted, _residuals = fit_dem_to_marginals(mechs, emp_marginals) + + return mechanisms_to_dem_string(fitted) + + +def build_adaptive_dem( + tick_circuit: object, + noise_params: dict[str, float], + *, + max_order: int = 2, + prune: float = 1e-12, +) -> tuple[str, str]: + """Build the best DEM using adaptive mechanism structure. + + Uses influence map mechanisms for stochastic noise sources and EEG + backward extraction mechanisms for coherent (idle_rz) noise sources. + Fits all mechanism probabilities to Heisenberg exact marginals + pairwise. + + Args: + tick_circuit: A ``TickCircuit`` with detector metadata. + noise_params: Dict with keys p1, p2, p_meas, p_prep, idle_rz. + max_order: Correlation order for Heisenberg targets (default 2). + prune: Pruning threshold for Heisenberg walks. + + Returns: + Tuple of (json_str, dem_str) — noise characterization JSON and + Stim DEM string. + """ + idle_rz = noise_params.get("idle_rz", 0.0) + + if idle_rz == 0.0 or idle_rz < 1e-10: + # Pure stochastic: from_circuit is best + from pecos_rslib.qec import DemSampler + + sampler = DemSampler.from_circuit( + tick_circuit, + p1=noise_params.get("p1", 0.0), + p2=noise_params.get("p2", 0.0), + p_meas=noise_params.get("p_meas", 0.0), + p_prep=noise_params.get("p_prep", 0.0), + ) + # For consistency, also compute correlation table + from pecos_rslib_exp import exact_correlation_table + + table = exact_correlation_table(tick_circuit, **noise_params, max_order=max_order) + # Return a minimal JSON with correlations + import json as _json + + json_out = _json.dumps({ + "correlations": [ + {"nodes": list(labels), "probability": prob} + for labels, prob in table + ], + }, indent=2) + # Get DEM string from the sampler's internal DEM + dem_str = "" # from_circuit doesn't expose DEM string directly + # Rebuild via DemBuilder + from pecos_rslib.qec import DemBuilder, DagFaultAnalyzer + + dag = tick_circuit.to_dag_circuit() + analyzer = DagFaultAnalyzer(dag) + influence = analyzer.build_influence_map() + builder = DemBuilder(influence) + builder = builder.with_noise( + p1=noise_params.get("p1", 0.0), + p2=noise_params.get("p2", 0.0), + p_meas=noise_params.get("p_meas", 0.0), + p_prep=noise_params.get("p_prep", 0.0), + ) + builder = builder.with_detectors_json(tick_circuit.get_meta("detectors")) + builder = builder.with_observables_json(tick_circuit.get_meta("observables")) + builder = builder.with_num_measurements( + int(tick_circuit.get_meta("num_measurements")) + ) + dem = builder.build() + dem_str = dem.to_string() + + return json_out, dem_str + + # Has coherent noise: use noise_characterization (EEG structure + L-BFGS fit) + from pecos_rslib_exp import noise_characterization + + return noise_characterization( + tick_circuit, **noise_params, max_order=max_order, prune=prune, + ) diff --git a/python/quantum-pecos/src/pecos/qec/surface/__init__.py b/python/quantum-pecos/src/pecos/qec/surface/__init__.py index aaaf51df5..0afd6a189 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/__init__.py +++ b/python/quantum-pecos/src/pecos/qec/surface/__init__.py @@ -27,6 +27,8 @@ StimRenderer, TickCircuitRenderer, build_surface_code_circuit, + classify_stabilizer_boundary, + describe_surface_memory_experiment, generate_dag_circuit_from_patch, generate_dem_from_tick_circuit, generate_dem_from_tick_circuit_via_autodetection, @@ -35,6 +37,13 @@ generate_guppy_from_patch, generate_stim_from_patch, generate_tick_circuit_from_patch, + get_detector_descriptors_from_tick_circuit, + get_measurement_order_from_tick_circuit, + get_observable_descriptors_from_tick_circuit, + get_stabilizer_region, + get_stabilizer_schedule_entries, + get_stabilizer_schedule_metadata, + get_stabilizer_touch_label, tick_circuit_to_stim, ) from pecos.qec.surface.circuit_builder import ( @@ -67,17 +76,27 @@ get_rotated_logical_x, get_rotated_logical_z, ) +from pecos.qec.surface.logical_circuit import ( + LogicalCircuitBuilder, + LogicalGateType, + LogicalOp, + PatchState, +) from pecos.qec.surface.parity import ( parity_matrix_x, parity_matrix_z, ) from pecos.qec.surface.patch import ( + LogicalDescriptor, LogicalOperator, PatchGeometry, PatchOrientation, Stabilizer, + StabilizerDescriptor, + StabilizerScheduleEntry, SurfacePatch, SurfacePatchBuilder, + SurfacePatchDescriptor, ) from pecos.qec.surface.plot import plot_patch, plot_surface_code from pecos.qec.surface.schedule import ( @@ -105,9 +124,13 @@ "parity_matrix_z", # Patch classes "LogicalOperator", + "LogicalDescriptor", "PatchGeometry", "PatchOrientation", "Stabilizer", + "StabilizerDescriptor", + "StabilizerScheduleEntry", + "SurfacePatchDescriptor", "SurfacePatch", "SurfacePatchBuilder", # Decoding @@ -137,6 +160,8 @@ "StimRenderer", "TickCircuitRenderer", "build_surface_code_circuit", + "classify_stabilizer_boundary", + "describe_surface_memory_experiment", "generate_dag_circuit_from_patch", "generate_dem_from_tick_circuit", "generate_dem_from_tick_circuit_via_autodetection", @@ -145,5 +170,17 @@ "generate_guppy_from_patch", "generate_stim_from_patch", "generate_tick_circuit_from_patch", + "get_detector_descriptors_from_tick_circuit", + "get_measurement_order_from_tick_circuit", + "get_observable_descriptors_from_tick_circuit", + "get_stabilizer_region", + "get_stabilizer_schedule_entries", + "get_stabilizer_schedule_metadata", + "get_stabilizer_touch_label", + # Logical circuit builder (transversal gates) + "LogicalCircuitBuilder", + "LogicalGateType", + "LogicalOp", + "PatchState", "tick_circuit_to_stim", ] diff --git a/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py b/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py index 37acd1a68..d775f1696 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py +++ b/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py @@ -19,13 +19,70 @@ from abc import ABC, abstractmethod from dataclasses import dataclass, field from enum import Enum, auto -from typing import TYPE_CHECKING +from typing import TYPE_CHECKING, TypedDict if TYPE_CHECKING: - from pecos.qec.surface.patch import SurfacePatch + from pecos.qec.surface.patch import ( + LogicalDescriptor, + Stabilizer, + StabilizerDescriptor, + SurfacePatch, + SurfacePatchDescriptor, + ) from pecos.quantum import DagCircuit, TickCircuit, TickHandle +class SurfaceDetectorDescriptor(TypedDict): + """Public detector descriptor derived from TickCircuit metadata.""" + + id: int + detector_id: int + stabilizer_kind: str + stabilizer_index: int + round: int + is_final_round: bool + coords: list[int] + records: list[int] + stabilizer_is_boundary: bool + stabilizer_region: str + schedule_rounds: list[int] + schedule_start_round: int | None + schedule_end_round: int | None + schedule_entries: list[dict[str, int | str]] + data_qubits: list[int] + data_qubit_positions: list[list[int]] + weight: int + + +class SurfaceObservableDescriptor(TypedDict): + """Public observable descriptor derived from TickCircuit metadata.""" + + id: int + observable_id: int + basis: str + records: list[int] + logical_type: str + data_qubits: list[int] + data_qubit_positions: list[list[int]] + weight: int + support_axis: str + + +class SurfaceMemoryExperimentDescriptor(TypedDict): + """Public bundle describing a surface-memory experiment.""" + + patch: SurfacePatchDescriptor + basis: str + num_rounds: int + ancilla_budget: int | None + x_stabilizers: list[StabilizerDescriptor] + z_stabilizers: list[StabilizerDescriptor] + stabilizers: list[StabilizerDescriptor] + logicals: list[LogicalDescriptor] + detectors: list[SurfaceDetectorDescriptor] + observables: list[SurfaceObservableDescriptor] + + class OpType(Enum): """Circuit operation types.""" @@ -69,13 +126,47 @@ class QubitAllocation: @property def total(self) -> int: """Total number of qubits.""" - return len(self.data_qubits) + len(self.x_ancilla_qubits) + len(self.z_ancilla_qubits) + return len(set(self.data_qubits) | set(self.x_ancilla_qubits) | set(self.z_ancilla_qubits)) + + +def _normalize_ancilla_budget(total_ancilla: int, ancilla_budget: int | None) -> int: + """Clamp ancilla budget to the valid range for a patch.""" + if ancilla_budget is None: + return total_ancilla + + if ancilla_budget < 1: + msg = f"ancilla_budget must be >= 1, got {ancilla_budget}" + raise ValueError(msg) + + return min(ancilla_budget, total_ancilla) + + +def _batched_stabilizers( + patch: SurfacePatch, + ancilla_budget: int, +) -> list[list[tuple[str, int]]]: + """Partition stabilizers into ancilla-reuse batches. + + This mirrors the public Guppy batching order so the abstract circuit and + its native DEMs match the actual low-ancilla circuit family. + """ + geom = patch.geometry + stabilizers = [("X", stab.index) for stab in geom.x_stabilizers] + stabilizers.extend(("Z", stab.index) for stab in geom.z_stabilizers) + # Sort key is load-bearing: it mirrors Guppy's stabilizer ordering (ascending + # index, X before Z on ties). Batched DEMs are compared against Guppy output + # shot-for-shot in the Selene parity tests, so any change here will diverge + # from the low-ancilla reference family. + stabilizers.sort(key=lambda stab: (stab[1], 0 if stab[0] == "X" else 1)) + + return [stabilizers[start : start + ancilla_budget] for start in range(0, len(stabilizers), ancilla_budget)] def build_surface_code_circuit( patch: SurfacePatch, num_rounds: int, basis: str = "Z", + ancilla_budget: int | None = None, ) -> tuple[list[CircuitOp], QubitAllocation]: """Build abstract circuit operations for a surface code memory experiment. @@ -88,6 +179,9 @@ def build_surface_code_circuit( patch: Surface code patch with geometry num_rounds: Number of syndrome extraction rounds basis: 'Z' for |0_L> state or 'X' for |+_L> state + ancilla_budget: Optional cap on simultaneously live ancillas. When + provided below the total stabilizer count, ancillas are reused + across stabilizer batches following the public Guppy order. Returns: Tuple of (operations list, qubit allocation info) @@ -98,15 +192,36 @@ def build_surface_code_circuit( num_data = geom.num_data num_x_anc = len(geom.x_stabilizers) num_z_anc = len(geom.z_stabilizers) + total_ancilla = num_x_anc + num_z_anc + effective_ancilla_budget = _normalize_ancilla_budget(total_ancilla, ancilla_budget) + + # Qubit allocation layout. Under ancilla reuse, stabilizers map onto a + # shared ancilla pool and different stabilizers can intentionally share the + # same physical qubit id at different times. + if effective_ancilla_budget == total_ancilla: + allocation = QubitAllocation( + data_qubits=list(range(num_data)), + x_ancilla_qubits=list(range(num_data, num_data + num_x_anc)), + z_ancilla_qubits=list( + range(num_data + num_x_anc, num_data + num_x_anc + num_z_anc), + ), + ) + else: + ancilla_pool = list(range(num_data, num_data + effective_ancilla_budget)) + x_ancilla_qubits = [-1] * num_x_anc + z_ancilla_qubits = [-1] * num_z_anc + for batch in _batched_stabilizers(patch, effective_ancilla_budget): + for pool_idx, (stab_type, stab_idx) in enumerate(batch): + if stab_type == "X": + x_ancilla_qubits[stab_idx] = ancilla_pool[pool_idx] + else: + z_ancilla_qubits[stab_idx] = ancilla_pool[pool_idx] - # Qubit allocation layout - allocation = QubitAllocation( - data_qubits=list(range(num_data)), - x_ancilla_qubits=list(range(num_data, num_data + num_x_anc)), - z_ancilla_qubits=list( - range(num_data + num_x_anc, num_data + num_x_anc + num_z_anc), - ), - ) + allocation = QubitAllocation( + data_qubits=list(range(num_data)), + x_ancilla_qubits=x_ancilla_qubits, + z_ancilla_qubits=z_ancilla_qubits, + ) def data_q(i: int) -> int: return allocation.data_qubits[i] @@ -143,47 +258,115 @@ def z_anc_q(stab_idx: int) -> int: ops.append( CircuitOp(OpType.COMMENT, label=f"syndrome_extraction round {rnd + 1}"), ) + if effective_ancilla_budget == total_ancilla: + ops.extend(CircuitOp(OpType.ALLOC, [x_anc_q(s.index)], f"ax{s.index}") for s in geom.x_stabilizers) + ops.extend(CircuitOp(OpType.ALLOC, [z_anc_q(s.index)], f"az{s.index}") for s in geom.z_stabilizers) - # Allocate X ancillas: ax{i} = qubit() - ops.extend(CircuitOp(OpType.ALLOC, [x_anc_q(s.index)], f"ax{s.index}") for s in geom.x_stabilizers) + ops.append(CircuitOp(OpType.COMMENT, label="Hadamard on X ancillas")) + ops.extend(CircuitOp(OpType.H, [x_anc_q(s.index)], f"ax{s.index}") for s in geom.x_stabilizers) - # Allocate Z ancillas: az{i} = qubit() - ops.extend(CircuitOp(OpType.ALLOC, [z_anc_q(s.index)], f"az{s.index}") for s in geom.z_stabilizers) + ops.append(CircuitOp(OpType.TICK)) - # H on X ancillas - ops.append(CircuitOp(OpType.COMMENT, label="Hadamard on X ancillas")) - ops.extend(CircuitOp(OpType.H, [x_anc_q(s.index)]) for s in geom.x_stabilizers) + for rnd_idx, cx_round in enumerate(cnot_rounds): + ops.append(CircuitOp(OpType.COMMENT, label=f"CX round {rnd_idx + 1}")) + for stab_type, stab_idx, data_idx in cx_round: + if stab_type == "X": + ops.append( + CircuitOp( + OpType.CX, + [x_anc_q(stab_idx), data_q(data_idx)], + f"X{stab_idx}", + ), + ) + else: + ops.append( + CircuitOp( + OpType.CX, + [data_q(data_idx), z_anc_q(stab_idx)], + f"Z{stab_idx}", + ), + ) + ops.append(CircuitOp(OpType.TICK)) - ops.append(CircuitOp(OpType.TICK)) + ops.append(CircuitOp(OpType.COMMENT, label="Hadamard on X ancillas")) + ops.extend(CircuitOp(OpType.H, [x_anc_q(s.index)], f"ax{s.index}") for s in geom.x_stabilizers) - # 4 CNOT rounds - for rnd_idx, cx_round in enumerate(cnot_rounds): - ops.append(CircuitOp(OpType.COMMENT, label=f"CX round {rnd_idx + 1}")) - for stab_type, stab_idx, data_idx in cx_round: - if stab_type == "X": - # cx(ax{stab_idx}, surf.data[{data_idx}]) + ops.append(CircuitOp(OpType.COMMENT, label="Measure ancillas")) + ops.extend(CircuitOp(OpType.MEASURE, [x_anc_q(s.index)], f"sx{s.index}") for s in geom.x_stabilizers) + ops.extend(CircuitOp(OpType.MEASURE, [z_anc_q(s.index)], f"sz{s.index}") for s in geom.z_stabilizers) + + ops.append(CircuitOp(OpType.TICK)) + else: + stabilizer_batches = _batched_stabilizers(patch, effective_ancilla_budget) + for batch in stabilizer_batches: + ops.append(CircuitOp(OpType.COMMENT, label="Prepare ancillas")) + batch_ancillas = { + (stab_type, stab_idx): x_anc_q(stab_idx) if stab_type == "X" else z_anc_q(stab_idx) + for stab_type, stab_idx in batch + } + + for stab_type, stab_idx in batch: ops.append( - CircuitOp(OpType.CX, [x_anc_q(stab_idx), data_q(data_idx)]), + CircuitOp( + OpType.ALLOC, + [batch_ancillas[(stab_type, stab_idx)]], + f"a{stab_type.lower()}{stab_idx}", + ), ) - else: - # cx(surf.data[{data_idx}], az{stab_idx}) - ops.append( - CircuitOp(OpType.CX, [data_q(data_idx), z_anc_q(stab_idx)]), + + x_stabilizers_in_batch = [stab_idx for stab_type, stab_idx in batch if stab_type == "X"] + if x_stabilizers_in_batch: + ops.append(CircuitOp(OpType.COMMENT, label="Hadamard on X ancillas")) + ops.extend( + CircuitOp(OpType.H, [batch_ancillas[("X", stab_idx)]], f"ax{stab_idx}") + for stab_idx in x_stabilizers_in_batch ) - ops.append(CircuitOp(OpType.TICK)) - # H on X ancillas (second time) - ops.append(CircuitOp(OpType.COMMENT, label="Hadamard on X ancillas")) - ops.extend(CircuitOp(OpType.H, [x_anc_q(s.index)]) for s in geom.x_stabilizers) + ops.append(CircuitOp(OpType.TICK)) + + for rnd_idx, cx_round in enumerate(cnot_rounds): + ops.append(CircuitOp(OpType.COMMENT, label=f"CX round {rnd_idx + 1}")) + for stab_type, stab_idx, data_idx in cx_round: + ancilla_q = batch_ancillas.get((stab_type, stab_idx)) + if ancilla_q is None: + continue + if stab_type == "X": + ops.append( + CircuitOp( + OpType.CX, + [ancilla_q, data_q(data_idx)], + f"X{stab_idx}", + ), + ) + else: + ops.append( + CircuitOp( + OpType.CX, + [data_q(data_idx), ancilla_q], + f"Z{stab_idx}", + ), + ) + ops.append(CircuitOp(OpType.TICK)) - # Measure X ancillas: sx{i} = measure(ax{i}) - ops.append(CircuitOp(OpType.COMMENT, label="Measure ancillas")) - ops.extend(CircuitOp(OpType.MEASURE, [x_anc_q(s.index)], f"sx{s.index}") for s in geom.x_stabilizers) + if x_stabilizers_in_batch: + ops.append(CircuitOp(OpType.COMMENT, label="Hadamard on X ancillas")) + ops.extend( + CircuitOp(OpType.H, [batch_ancillas[("X", stab_idx)]], f"ax{stab_idx}") + for stab_idx in x_stabilizers_in_batch + ) - # Measure Z ancillas: sz{i} = measure(az{i}) - ops.extend(CircuitOp(OpType.MEASURE, [z_anc_q(s.index)], f"sz{s.index}") for s in geom.z_stabilizers) + ops.append(CircuitOp(OpType.COMMENT, label="Measure ancillas")) + for stab_type, stab_idx in batch: + measure_label = f"sx{stab_idx}" if stab_type == "X" else f"sz{stab_idx}" + ops.append( + CircuitOp( + OpType.MEASURE, + [batch_ancillas[(stab_type, stab_idx)]], + measure_label, + ), + ) - ops.append(CircuitOp(OpType.TICK)) + ops.append(CircuitOp(OpType.TICK)) # ========================================================================= # measure_z_basis / measure_x_basis @@ -200,6 +383,148 @@ def z_anc_q(stab_idx: int) -> int: return ops, allocation +def classify_stabilizer_boundary(stab_type: str, data_qubits: tuple[int, ...], d: int, dz: int | None = None) -> str: + """Public wrapper for classifying a boundary stabilizer.""" + from pecos.qec.surface.schedule import _classify_boundary + + if dz is None: + dz = d + return _classify_boundary(stab_type, data_qubits, d, dz) + + +def get_stabilizer_region(stab: Stabilizer, patch: SurfacePatch) -> str: + """Return a coarse region label like ``top+left`` for a stabilizer.""" + geom = patch.geometry + positions = [geom.id_to_pos[q] for q in stab.data_qubits] + avg_row = sum(row for row, _ in positions) / len(positions) + avg_col = sum(col for _, col in positions) / len(positions) + row_label = "top" if avg_row < (geom.dx - 1) / 2 else "bottom" + col_label = "left" if avg_col < (geom.dz - 1) / 2 else "right" + return f"{row_label}+{col_label}" + + +def get_stabilizer_touch_label(stab: Stabilizer, patch: SurfacePatch, data_qubit: int) -> str: + """Label how a data qubit sits relative to a stabilizer support.""" + geom = patch.geometry + if data_qubit not in stab.data_qubits: + msg = f"Qubit {data_qubit} is not in stabilizer {stab.stab_type}{stab.index}" + raise ValueError(msg) + + positions = [geom.id_to_pos[q] for q in stab.data_qubits] + data_row, data_col = geom.id_to_pos[data_qubit] + rows = [row for row, _ in positions] + cols = [col for _, col in positions] + + if len(set(rows)) == 1: + return "left" if data_col == min(cols) else "right" + if len(set(cols)) == 1: + return "top" if data_row == min(rows) else "bottom" + + vertical = "T" if data_row == min(rows) else "B" + horizontal = "L" if data_col == min(cols) else "R" + return vertical + horizontal + + +def get_stabilizer_schedule_entries(stab: Stabilizer, patch: SurfacePatch) -> list[dict[str, int | str]]: + """Return the per-round touch schedule for one stabilizer.""" + from pecos.qec.surface.schedule import get_stab_schedule + + schedule = get_stab_schedule(stab.stab_type, stab.data_qubits, stab.is_boundary, patch.dx, patch.dz) + return [ + { + "round_0based": round_0based, + "data_qubit": data_qubit, + "touch_label": get_stabilizer_touch_label(stab, patch, data_qubit), + } + for round_0based, data_qubit in schedule + ] + + +def get_stabilizer_schedule_metadata(stab: Stabilizer, patch: SurfacePatch) -> dict[str, object]: + """Return metadata describing one stabilizer's schedule and geometry.""" + entries = get_stabilizer_schedule_entries(stab, patch) + rounds = [int(entry["round_0based"]) for entry in entries] + return { + "stabilizer_kind": stab.stab_type, + "stabilizer_index": stab.index, + "stabilizer_is_boundary": stab.is_boundary, + "stabilizer_region": get_stabilizer_region(stab, patch), + "schedule_rounds": rounds, + "schedule_start_round": rounds[0] if rounds else None, + "schedule_end_round": rounds[-1] if rounds else None, + "schedule_entries": entries, + } + + +def _build_detector_descriptors( + detectors: list[dict[str, object]], + patch: SurfacePatch, +) -> list[SurfaceDetectorDescriptor]: + """Build enriched detector descriptors from TickCircuit detector metadata.""" + num_x_anc = len(patch.x_stabilizers) + final_round = max((int(det["coords"][2]) for det in detectors), default=-1) + descriptors: list[SurfaceDetectorDescriptor] = [] + + for det in detectors: + coords = [int(value) for value in det["coords"]] + records = [int(value) for value in det["records"]] + raw_index = coords[0] + if coords[1] == 0: + stab_kind = "X" + stab_index = raw_index + else: + stab_kind = "Z" + stab_index = raw_index - num_x_anc + + descriptor = patch.get_stabilizer_descriptor(stab_kind, stab_index) + descriptors.append( + { + "id": int(det["id"]), + "detector_id": int(det["id"]), + "stabilizer_kind": descriptor["stabilizer_kind"], + "stabilizer_index": descriptor["stabilizer_index"], + "round": coords[2], + "is_final_round": coords[2] == final_round, + "coords": coords, + "records": records, + "stabilizer_is_boundary": descriptor["stabilizer_is_boundary"], + "stabilizer_region": descriptor["stabilizer_region"], + "schedule_rounds": descriptor["schedule_rounds"], + "schedule_start_round": descriptor["schedule_start_round"], + "schedule_end_round": descriptor["schedule_end_round"], + "schedule_entries": descriptor["schedule_entries"], + "data_qubits": descriptor["data_qubits"], + "data_qubit_positions": descriptor["data_qubit_positions"], + "weight": descriptor["weight"], + }, + ) + + return descriptors + + +def _build_observable_descriptors( + observables: list[dict[str, object]], + patch: SurfacePatch, + basis: str, +) -> list[SurfaceObservableDescriptor]: + """Build enriched logical observable descriptors from TickCircuit metadata.""" + logical = patch.get_logical_descriptor(basis.upper()) + return [ + { + "id": int(obs["id"]), + "observable_id": int(obs["id"]), + "basis": basis.upper(), + "records": [int(value) for value in obs["records"]], + "logical_type": logical["logical_type"], + "data_qubits": logical["data_qubits"], + "data_qubit_positions": logical["data_qubit_positions"], + "weight": logical["weight"], + "support_axis": logical["support_axis"], + } + for obs in observables + ] + + class CircuitRenderer(ABC): """Abstract base class for circuit renderers.""" @@ -224,7 +549,7 @@ def __init__( p1: float = 0.0, p2: float = 0.0, p_meas: float = 0.0, - p_init: float = 0.0, + p_prep: float = 0.0, add_detectors: bool = True, ) -> None: """Initialize Stim renderer. @@ -233,13 +558,13 @@ def __init__( p1: Single-qubit depolarizing error rate p2: Two-qubit depolarizing error rate p_meas: Measurement error rate - p_init: Initialization error rate + p_prep: Initialization error rate add_detectors: Whether to add DETECTOR annotations """ self.p1 = p1 self.p2 = p2 self.p_meas = p_meas - self.p_init = p_init + self.p_prep = p_prep self.add_detectors = add_detectors def render( @@ -275,8 +600,8 @@ def render( elif op.op_type == OpType.ALLOC: lines.append(f"R {op.qubits[0]}") - if self.p_init > 0: - lines.append(f"X_ERROR({self.p_init}) {op.qubits[0]}") + if self.p_prep > 0: + lines.append(f"X_ERROR({self.p_prep}) {op.qubits[0]}") elif op.op_type == OpType.H: lines.append(f"H {op.qubits[0]}") @@ -542,6 +867,7 @@ def render( from pecos_rslib.quantum import TickCircuit circuit = TickCircuit() + geom = patch.geometry allocated: set[int] = set() current_tick_handle = None current_tick_idx = -1 @@ -550,6 +876,8 @@ def render( # Track measurements for detector annotations meas_count = 0 stab_meas_record: dict[tuple[str, int, int], int] = {} + stab_meas_refs: dict[tuple[str, int, int], list] = {} + final_meas_refs_by_qubit: dict[int, list] = {} current_round = -1 current_phase = "prep" current_cx_round = 0 @@ -560,9 +888,24 @@ def render( # Format: {tick_idx: {'phase': str, 'round': int, 'cx_round': int, 'gates': [(label, role), ...]}} all_tick_metadata: dict[int, dict] = {} + def get_stabilizer_from_label(label: str) -> str: + """Decode surface stabilizer identity from an operation label.""" + if not label: + return "" + if label[0] in {"X", "Z"} and label[1:].isdigit(): + return label + if label.startswith(("ax", "sx")) and label[2:].isdigit(): + return f"X{int(label[2:])}" + if label.startswith(("az", "sz")) and label[2:].isdigit(): + return f"Z{int(label[2:])}" + return "" + # Helper to get stabilizer name for a CX gate - def get_cx_stabilizer(control: int, target: int) -> str: + def get_cx_stabilizer(control: int, target: int, label: str = "") -> str: """Get stabilizer name for a CX gate (e.g., 'X0', 'Z2').""" + from_label = get_stabilizer_from_label(label) + if from_label: + return from_label if control in allocation.x_ancilla_qubits: # X stabilizer: ancilla is control stab_idx = allocation.x_ancilla_qubits.index(control) @@ -573,6 +916,56 @@ def get_cx_stabilizer(control: int, target: int) -> str: return f"Z{stab_idx}" return "" + stabilizer_by_label = { + **{f"X{s.index}": s for s in geom.x_stabilizers}, + **{f"Z{s.index}": s for s in geom.z_stabilizers}, + } + stabilizer_by_ancilla_qubit = { + **{allocation.x_ancilla_qubits[s.index]: f"X{s.index}" for s in geom.x_stabilizers}, + **{allocation.z_ancilla_qubits[s.index]: f"Z{s.index}" for s in geom.z_stabilizers}, + } + + def get_stabilizer_metadata(stab_label: str) -> dict[str, object]: + stab = stabilizer_by_label[stab_label] + return { + "stabilizer": stab_label, + "stabilizer_kind": stab.stab_type, + "stabilizer_index": stab.index, + "stabilizer_is_boundary": stab.is_boundary, + "stabilizer_region": get_stabilizer_region(stab, patch), + } + + def get_ancilla_gate_metadata(qubit: int, label: str = "") -> dict[str, object]: + stab_label = get_stabilizer_from_label(label) or stabilizer_by_ancilla_qubit.get(qubit) + if stab_label is None: + return {} + metadata = get_stabilizer_metadata(stab_label) + metadata["ancilla_qubit"] = qubit + return metadata + + def get_cx_gate_metadata(control: int, target: int, label: str = "") -> dict[str, object]: + stab_label = get_cx_stabilizer(control, target, label) + if not stab_label: + return {} + metadata = get_stabilizer_metadata(stab_label) + ancilla_qubit = next( + (q for q in (control, target) if q in stabilizer_by_ancilla_qubit), + None, + ) + data_qubit = next((q for q in (control, target) if q in allocation.data_qubits), None) + if ancilla_qubit is not None: + metadata["ancilla_qubit"] = ancilla_qubit + if data_qubit is not None: + metadata["data_qubit"] = data_qubit + metadata["touch_label"] = get_stabilizer_touch_label( + stabilizer_by_label[stab_label], + patch, + data_qubit, + ) + if current_cx_round > 0: + metadata["cx_round_0based"] = current_cx_round - 1 + return metadata + def new_tick() -> TickHandle: nonlocal current_tick_handle, current_tick_idx, qubits_in_current_tick current_tick_handle = circuit.tick() @@ -611,7 +1004,17 @@ def queue_gate_metadata(meta: dict | None = None) -> None: meta: Optional dict with gate metadata (e.g., {"label": "data[0]"}) """ if current_tick_idx >= 0: - all_tick_metadata[current_tick_idx]["gates"].append(meta or {}) + context = { + "phase": current_phase, + } + if current_round >= 0: + context["syndrome_round"] = current_round + if current_cx_round > 0: + context["cx_round"] = current_cx_round + merged_meta = context + if meta: + merged_meta = {**context, **meta} + all_tick_metadata[current_tick_idx]["gates"].append(merged_meta) for op in ops: if op.op_type == OpType.COMMENT: @@ -620,6 +1023,9 @@ def queue_gate_metadata(meta: dict | None = None) -> None: current_round = int(op.label.split()[-1]) - 1 current_phase = "syndrome_prep" current_cx_round = 0 + elif "Prepare ancillas" in op.label: + current_phase = "syndrome_prep" + current_cx_round = 0 elif "Hadamard on X ancillas" in op.label: current_phase = "syndrome_h_pre" if current_phase == "syndrome_prep" else "syndrome_h_post" elif "CX round" in op.label: @@ -642,57 +1048,80 @@ def queue_gate_metadata(meta: dict | None = None) -> None: tick.pz([q]) mark_qubits_used([q]) # Label helps identify which qubit (e.g., "data[0]", "ax0") - queue_gate_metadata({"label": op.label} if op.label else None) + meta = get_ancilla_gate_metadata(q, op.label) + if op.label: + meta["label"] = op.label + queue_gate_metadata(meta or None) elif op.op_type == OpType.PREP: q = op.qubits[0] get_tick_for_qubits([q]).pz([q]) mark_qubits_used([q]) - queue_gate_metadata() + meta = get_ancilla_gate_metadata(q, op.label) + if op.label: + meta["label"] = op.label + queue_gate_metadata(meta or None) elif op.op_type == OpType.H: q = op.qubits[0] get_tick_for_qubits([q]).h([q]) mark_qubits_used([q]) - queue_gate_metadata() + meta = get_ancilla_gate_metadata(q, op.label) + if op.label: + meta["label"] = op.label + queue_gate_metadata(meta or None) elif op.op_type == OpType.X: q = op.qubits[0] get_tick_for_qubits([q]).x([q]) mark_qubits_used([q]) - queue_gate_metadata() + meta = get_ancilla_gate_metadata(q, op.label) + if op.label: + meta["label"] = op.label + queue_gate_metadata(meta or None) elif op.op_type == OpType.Z: q = op.qubits[0] get_tick_for_qubits([q]).z([q]) mark_qubits_used([q]) - queue_gate_metadata() + meta = get_ancilla_gate_metadata(q, op.label) + if op.label: + meta["label"] = op.label + queue_gate_metadata(meta or None) elif op.op_type == OpType.CX: qubits = op.qubits get_tick_for_qubits(qubits).cx([(qubits[0], qubits[1])]) mark_qubits_used(qubits) - # Stabilizer name helps identify which stabilizer (e.g., "X0", "Z2") - stab = get_cx_stabilizer(qubits[0], qubits[1]) - queue_gate_metadata({"stabilizer": stab} if stab else None) + meta = get_cx_gate_metadata(qubits[0], qubits[1], op.label) + if op.label: + meta["label"] = op.label + queue_gate_metadata(meta or None) elif op.op_type == OpType.MEASURE: q = op.qubits[0] - get_tick_for_qubits([q]).mz([q]) + meas_refs = get_tick_for_qubits([q]).mz([q]) mark_qubits_used([q]) # Label helps identify measurement (e.g., "sx0", "sz0", "final[0]") - queue_gate_metadata({"label": op.label} if op.label else None) + meta = get_ancilla_gate_metadata(q, op.label) + if op.label: + meta["label"] = op.label + queue_gate_metadata(meta or None) - # Track measurement index for detectors + # Track measurement index and refs for detectors if op.label.startswith("sx"): stab_idx = int(op.label[2:]) stab_meas_record[("X", stab_idx, current_round)] = meas_count + stab_meas_refs[("X", stab_idx, current_round)] = meas_refs elif op.label.startswith("sz"): stab_idx = int(op.label[2:]) stab_meas_record[("Z", stab_idx, current_round)] = meas_count + stab_meas_refs[("Z", stab_idx, current_round)] = meas_refs elif op.label.startswith("final"): if "final[0]" in op.label: final_meas_start = meas_count + # Track all final measurement refs by data qubit + final_meas_refs_by_qubit[q] = meas_refs meas_count += 1 elif op.op_type == OpType.TICK: @@ -820,15 +1249,103 @@ def queue_gate_metadata(meta: dict | None = None) -> None: }, ] - # Store as metadata + # Store as metadata (legacy path for DemBuilder/caching) circuit.set_meta("detectors", json.dumps(detectors)) circuit.set_meta("observables", json.dumps(observables)) circuit.set_meta("num_measurements", str(meas_count)) circuit.set_meta("num_detectors", str(len(detectors))) - circuit.set_meta("basis", basis.upper()) + + # Also add typed PauliAnnotation annotations (new path) + self._add_typed_annotations( + circuit, + geom, + num_rounds, + basis, + stab_meas_refs, + final_meas_refs_by_qubit, + deterministic_type_round0, + ) + circuit.set_meta("basis", basis.upper()) + circuit.set_meta("ancilla_budget", str(allocation.total - len(allocation.data_qubits))) return circuit + @staticmethod + def _add_typed_annotations( + circuit: TickCircuit, + geom: object, + num_rounds: int, + basis: str, + stab_meas_refs: dict, + final_meas_refs_by_qubit: dict, + deterministic_type_round0: str, + ) -> None: + """Add typed PauliAnnotation detectors and observables to the circuit. + + This mirrors the JSON detector logic but uses the new annotation API + with TickMeasRef measurement references. + """ + # Syndrome detectors for X stabilizers + for rnd in range(num_rounds): + for s in geom.x_stabilizers: + curr_refs = stab_meas_refs.get(("X", s.index, rnd)) + if curr_refs is None: + continue + if rnd == 0: + if deterministic_type_round0 == "X": + circuit.detector(curr_refs, label=f"Sx{s.index}_r{rnd}") + else: + prev_refs = stab_meas_refs.get(("X", s.index, rnd - 1), []) + circuit.detector(prev_refs + curr_refs, label=f"Sx{s.index}_r{rnd}") + + # Syndrome detectors for Z stabilizers + for rnd in range(num_rounds): + for s in geom.z_stabilizers: + curr_refs = stab_meas_refs.get(("Z", s.index, rnd)) + if curr_refs is None: + continue + if rnd == 0: + if deterministic_type_round0 == "Z": + circuit.detector(curr_refs, label=f"Sz{s.index}_r{rnd}") + else: + prev_refs = stab_meas_refs.get(("Z", s.index, rnd - 1), []) + circuit.detector(prev_refs + curr_refs, label=f"Sz{s.index}_r{rnd}") + + # Final detectors + if basis.upper() == "Z": + stabilizers = geom.z_stabilizers + stab_type = "Z" + logical_qubits = list(geom.logical_z.data_qubits) if geom.logical_z else [] + else: + stabilizers = geom.x_stabilizers + stab_type = "X" + logical_qubits = list(geom.logical_x.data_qubits) if geom.logical_x else [] + + for s in stabilizers: + # Data qubit measurement refs for this stabilizer + data_refs = [] + for dq in s.data_qubits: + if dq in final_meas_refs_by_qubit: + data_refs.extend(final_meas_refs_by_qubit[dq]) + # Last syndrome round ref + last_syn_refs = stab_meas_refs.get( + (stab_type, s.index, num_rounds - 1), + [], + ) + label_prefix = "Sx" if stab_type == "X" else "Sz" + circuit.detector( + data_refs + last_syn_refs, + label=f"{label_prefix}{s.index}_final", + ) + + # Logical observable + obs_refs = [] + for q in logical_qubits: + if q in final_meas_refs_by_qubit: + obs_refs.extend(final_meas_refs_by_qubit[q]) + if obs_refs: + circuit.observable(obs_refs, label=f"logical_{basis.upper()}") + # Convenience functions @@ -838,10 +1355,11 @@ def generate_stim_from_patch( num_rounds: int, basis: str = "Z", *, + ancilla_budget: int | None = None, p1: float = 0.0, p2: float = 0.0, p_meas: float = 0.0, - p_init: float = 0.0, + p_prep: float = 0.0, ) -> str: """Generate Stim circuit from SurfacePatch. @@ -849,16 +1367,17 @@ def generate_stim_from_patch( patch: Surface code patch num_rounds: Number of syndrome rounds basis: 'Z' or 'X' + ancilla_budget: Optional cap on simultaneously live ancillas p1: Single-qubit error rate p2: Two-qubit error rate p_meas: Measurement error rate - p_init: Initialization error rate + p_prep: Initialization error rate Returns: Stim circuit string """ - ops, allocation = build_surface_code_circuit(patch, num_rounds, basis) - renderer = StimRenderer(p1=p1, p2=p2, p_meas=p_meas, p_init=p_init) + ops, allocation = build_surface_code_circuit(patch, num_rounds, basis, ancilla_budget) + renderer = StimRenderer(p1=p1, p2=p2, p_meas=p_meas, p_prep=p_prep) return renderer.render(ops, allocation, patch, num_rounds, basis) @@ -894,6 +1413,7 @@ def generate_dag_circuit_from_patch( patch: SurfacePatch, num_rounds: int, basis: str = "Z", + ancilla_budget: int | None = None, ) -> DagCircuit: """Generate PECOS DagCircuit from SurfacePatch. @@ -901,11 +1421,12 @@ def generate_dag_circuit_from_patch( patch: Surface code patch num_rounds: Number of syndrome rounds basis: 'Z' or 'X' + ancilla_budget: Optional cap on simultaneously live ancillas Returns: PECOS DagCircuit instance """ - ops, allocation = build_surface_code_circuit(patch, num_rounds, basis) + ops, allocation = build_surface_code_circuit(patch, num_rounds, basis, ancilla_budget) renderer = DagCircuitRenderer() return renderer.render(ops, allocation, patch, num_rounds, basis) @@ -916,6 +1437,7 @@ def generate_tick_circuit_from_patch( basis: str = "Z", *, add_detectors: bool = True, + ancilla_budget: int | None = None, ) -> TickCircuit: """Generate PECOS TickCircuit from SurfacePatch. @@ -937,22 +1459,128 @@ def generate_tick_circuit_from_patch( num_rounds: Number of syndrome rounds basis: 'Z' or 'X' add_detectors: Whether to add detector annotations as metadata + ancilla_budget: Optional cap on simultaneously live ancillas Returns: PECOS TickCircuit instance """ - ops, allocation = build_surface_code_circuit(patch, num_rounds, basis) + ops, allocation = build_surface_code_circuit(patch, num_rounds, basis, ancilla_budget) renderer = TickCircuitRenderer(add_detectors=add_detectors) return renderer.render(ops, allocation, patch, num_rounds, basis) +def get_detector_descriptors_from_tick_circuit( + tick_circuit: TickCircuit, + patch: SurfacePatch, +) -> list[SurfaceDetectorDescriptor]: + """Return structured detector descriptors for a generated TickCircuit. + + The returned descriptors are cached in TickCircuit metadata when the circuit + is created by :func:`generate_tick_circuit_from_patch`. + + Example: + >>> from pecos.qec.surface import SurfacePatch, generate_tick_circuit_from_patch + >>> patch = SurfacePatch.create(distance=3) + >>> tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="Z") + >>> len(get_detector_descriptors_from_tick_circuit(tc, patch)) + 12 + """ + import json + + cached = tick_circuit.get_meta("detector_descriptors") + if cached: + return json.loads(cached) + + detectors = json.loads(tick_circuit.get_meta("detectors") or "[]") + descriptors = _build_detector_descriptors(detectors, patch) + tick_circuit.set_meta("detector_descriptors", json.dumps(descriptors)) + return descriptors + + +def get_observable_descriptors_from_tick_circuit( + tick_circuit: TickCircuit, + patch: SurfacePatch, +) -> list[SurfaceObservableDescriptor]: + """Return structured logical observable descriptors for a TickCircuit. + + Example: + >>> from pecos.qec.surface import SurfacePatch, generate_tick_circuit_from_patch + >>> patch = SurfacePatch.create(distance=3) + >>> tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="X") + >>> get_observable_descriptors_from_tick_circuit(tc, patch)[0]["basis"] + 'X' + """ + import json + + cached = tick_circuit.get_meta("observable_descriptors") + if cached: + return json.loads(cached) + + observables = json.loads(tick_circuit.get_meta("observables") or "[]") + basis = tick_circuit.get_meta("basis") or "Z" + descriptors = _build_observable_descriptors(observables, patch, basis) + tick_circuit.set_meta("observable_descriptors", json.dumps(descriptors)) + return descriptors + + +def describe_surface_memory_experiment( + patch: SurfacePatch, + num_rounds: int, + basis: str = "Z", + *, + add_detectors: bool = True, + ancilla_budget: int | None = None, +) -> SurfaceMemoryExperimentDescriptor: + """Return a structured descriptor bundle for a surface-memory experiment. + + This is a convenience wrapper for users who want one public entry point + that covers patch geometry, stabilizers, logicals, detectors, and + observables for a generated memory circuit. + + The descriptor helpers are regression-covered on rotated memory circuits and + also exposed for non-rotated and asymmetric patches created by + :class:`pecos.qec.surface.SurfacePatch`. + + Example: + >>> from pecos.qec.surface import SurfacePatch, describe_surface_memory_experiment + >>> summary = describe_surface_memory_experiment(SurfacePatch.create(distance=3), 2, basis="X") + >>> summary["basis"] + 'X' + """ + tick_circuit = generate_tick_circuit_from_patch( + patch, + num_rounds=num_rounds, + basis=basis, + add_detectors=add_detectors, + ancilla_budget=ancilla_budget, + ) + x_stabilizers = list(patch.iter_stabilizer_descriptors("X")) + z_stabilizers = list(patch.iter_stabilizer_descriptors("Z")) + logicals = list(patch.iter_logical_descriptors()) + detectors = get_detector_descriptors_from_tick_circuit(tick_circuit, patch) + observables = get_observable_descriptors_from_tick_circuit(tick_circuit, patch) + + return { + "patch": patch.get_patch_descriptor(), + "basis": basis.upper(), + "num_rounds": num_rounds, + "ancilla_budget": ancilla_budget, + "x_stabilizers": x_stabilizers, + "z_stabilizers": z_stabilizers, + "stabilizers": x_stabilizers + z_stabilizers, + "logicals": logicals, + "detectors": detectors, + "observables": observables, + } + + def tick_circuit_to_stim( tc: TickCircuit, *, p1: float = 0.0, p2: float = 0.0, p_meas: float = 0.0, - p_init: float = 0.0, + p_prep: float = 0.0, ) -> str: """Convert TickCircuit to Stim circuit string. @@ -964,78 +1592,135 @@ def tick_circuit_to_stim( p1: Single-qubit error rate p2: Two-qubit error rate p_meas: Measurement error rate - p_init: Initialization error rate + p_prep: Initialization error rate Returns: Stim circuit string """ import json + import math lines = [] - # Track measurement count for DETECTOR record references - measurement_count = 0 - - # Map gate type names to Stim instructions - gate_map = { - "H": "H", - "X": "X", - "Y": "Y", - "Z": "Z", - "CX": "CX", - "CY": "CY", - "CZ": "CZ", - "MZ": "M", - "PZ": "R", - "QAlloc": "R", # QAlloc treated as reset + simple_gate_map = { + "H": ("H", "single"), + "X": ("X", "single"), + "Y": ("Y", "single"), + "Z": ("Z", "single"), + "CX": ("CX", "two"), + "CY": ("CY", "two"), + "CZ": ("CZ", "two"), + "MZ": ("M", "measure"), + "PZ": ("R", "prep"), + "QAlloc": ("R", "prep"), } + def _normalized_angle(angle: float) -> float: + value = angle % math.tau + if math.isclose(value, math.tau, abs_tol=1e-9): + return 0.0 + return value + + def _is_close_turn(angle: float, target: float) -> bool: + return math.isclose(_normalized_angle(angle), target, abs_tol=1e-9) + + def _gate_to_stim( + gate: object, + ) -> tuple[list[tuple[str, list[int]]], str | None]: + gate_name = gate.gate_type.name + qubits = [int(q) for q in gate.qubits] + + mapped = simple_gate_map.get(gate_name) + if mapped is not None: + stim_name, noise_kind = mapped + return [(stim_name, qubits)], noise_kind + + if gate_name == "RZ": + if not gate.angles: + return [], None + angle = float(gate.angles[0]) + if _is_close_turn(angle, 0.0): + return [], None + if _is_close_turn(angle, math.pi): + return [("Z", qubits)], "single" + if _is_close_turn(angle, math.pi / 2): + return [("S", qubits)], "single" + if _is_close_turn(angle, 3 * math.pi / 2): + return [("S_DAG", qubits)], "single" + msg = f"Unsupported traced Clifford RZ angle: {angle!r}" + raise ValueError(msg) + + if gate_name == "RZZ": + if not gate.angles: + return [], None + angle = float(gate.angles[0]) + if _is_close_turn(angle, 0.0): + return [], None + if _is_close_turn(angle, math.pi / 2): + return [("SQRT_ZZ", qubits)], "two" + if _is_close_turn(angle, 3 * math.pi / 2): + return [("SQRT_ZZ_DAG", qubits)], "two" + msg = f"Unsupported traced Clifford RZZ angle: {angle!r}" + raise ValueError(msg) + + if gate_name == "R1XY": + if len(gate.angles) < 2: + return [], None + theta = float(gate.angles[0]) + phi = float(gate.angles[1]) + if _is_close_turn(theta, 0.0): + return [], None + if _is_close_turn(theta, math.pi): + if _is_close_turn(phi, 0.0) or _is_close_turn(phi, math.pi): + return [("X", qubits)], "single" + if _is_close_turn(phi, math.pi / 2) or _is_close_turn(phi, 3 * math.pi / 2): + return [("Y", qubits)], "single" + if _is_close_turn(theta, math.pi / 2): + if _is_close_turn(phi, 0.0): + return [("SQRT_X", qubits)], "single" + if _is_close_turn(phi, math.pi / 2): + return [("SQRT_Y", qubits)], "single" + if _is_close_turn(phi, math.pi): + return [("SQRT_X_DAG", qubits)], "single" + if _is_close_turn(phi, 3 * math.pi / 2): + return [("SQRT_Y_DAG", qubits)], "single" + if _is_close_turn(theta, 3 * math.pi / 2): + if _is_close_turn(phi, 0.0): + return [("SQRT_X_DAG", qubits)], "single" + if _is_close_turn(phi, math.pi / 2): + return [("SQRT_Y_DAG", qubits)], "single" + if _is_close_turn(phi, math.pi): + return [("SQRT_X", qubits)], "single" + if _is_close_turn(phi, 3 * math.pi / 2): + return [("SQRT_Y", qubits)], "single" + msg = f"Unsupported traced Clifford R1XY angles: theta={theta!r}, phi={phi!r}" + raise ValueError(msg) + + return [], None + for tick_idx in range(tc.num_ticks()): tick = tc.get_tick(tick_idx) - - # Group gates by type for efficient Stim output - gates_by_type: dict[str, list[int]] = {} - for gate in tick.gates(): - gate_type = gate.gate_type - stim_name = gate_map.get(gate_type.name) - - if stim_name is None: + instructions, noise_kind = _gate_to_stim(gate) + if not instructions: continue - qubits = list(gate.qubits) - - if stim_name not in gates_by_type: - gates_by_type[stim_name] = [] + qubits = [int(q) for q in gate.qubits] + qubit_str = " ".join(str(q) for q in qubits) - if stim_name == "CX": - # Two-qubit gate - gates_by_type[stim_name].extend(qubits) - else: - # Single-qubit gate - gates_by_type[stim_name].extend(qubits) + if noise_kind == "measure" and p_meas > 0: + lines.append(f"X_ERROR({p_meas}) {qubit_str}") - # Output gates grouped by type - for stim_name, qubits in gates_by_type.items(): - if not qubits: - continue - - qubit_str = " ".join(str(q) for q in qubits) - lines.append(f"{stim_name} {qubit_str}") + for stim_name, op_qubits in instructions: + op_qubit_str = " ".join(str(q) for q in op_qubits) + lines.append(f"{stim_name} {op_qubit_str}") - # Add noise after gates - if stim_name in ("H", "X", "Y", "Z") and p1 > 0: + if noise_kind == "single" and p1 > 0: lines.append(f"DEPOLARIZE1({p1}) {qubit_str}") - elif stim_name == "CX" and p2 > 0: + elif noise_kind == "two" and p2 > 0: lines.append(f"DEPOLARIZE2({p2}) {qubit_str}") - elif stim_name == "R" and p_init > 0: - lines.append(f"X_ERROR({p_init}) {qubit_str}") - elif stim_name == "M": - if p_meas > 0: - # Add measurement error before the M instruction - # Need to insert before the M line - lines.insert(-1, f"X_ERROR({p_meas}) {qubit_str}") - measurement_count += len(qubits) + elif noise_kind == "prep" and p_prep > 0: + lines.append(f"X_ERROR({p_prep}) {qubit_str}") # Add TICK after each tick (except the last) if tick_idx < tc.num_ticks() - 1: @@ -1099,7 +1784,7 @@ def generate_dem_from_patch( p1=p, p2=p, p_meas=p, - p_init=p, + p_prep=p, ) circuit = stim.Circuit(circuit_str) return str(circuit.detector_error_model()) @@ -1111,7 +1796,7 @@ def generate_dem_from_tick_circuit_via_pauli_frame( p1: float = 0.01, p2: float = 0.01, p_meas: float = 0.01, - p_init: float = 0.01, + p_prep: float = 0.01, ) -> str: """Generate DEM from TickCircuit using pure Python Pauli frame simulation. @@ -1127,7 +1812,7 @@ def generate_dem_from_tick_circuit_via_pauli_frame( p1: Single-qubit depolarizing error rate p2: Two-qubit depolarizing error rate p_meas: Measurement error rate - p_init: Initialization (prep) error rate + p_prep: Initialization (prep) error rate Returns: DEM string in Stim-compatible format @@ -1304,13 +1989,13 @@ def simulate_error( # Process each gate as a potential error location for op_idx, (_tick_idx, gate_name, qubits, meas_idx) in enumerate(circuit_ops): - if gate_name in ("QAlloc", "PZ") and p_init > 0: + if gate_name in ("QAlloc", "PZ") and p_prep > 0: # Initialization error: X error after prep q = qubits[0] dets, obs = simulate_error(op_idx + 1, {q: "X"}) if dets or obs: key = (frozenset(dets), frozenset(obs)) - error_mechanisms[key] += p_init + error_mechanisms[key] += p_prep elif gate_name == "H" and p1 > 0: # Single-qubit gate error: depolarizing (each Pauli with prob p1/3) @@ -1383,7 +2068,9 @@ def generate_dem_from_tick_circuit_via_stim( p1: float = 0.01, p2: float = 0.01, p_meas: float = 0.01, - p_init: float = 0.01, + p_prep: float = 0.01, + decompose_errors: bool = True, + maximal_decomposition: bool = False, ) -> str: """Generate DEM from TickCircuit via Stim conversion. @@ -1396,7 +2083,13 @@ def generate_dem_from_tick_circuit_via_stim( p1: Single-qubit depolarizing error rate p2: Two-qubit depolarizing error rate p_meas: Measurement error rate - p_init: Initialization (prep) error rate + p_prep: Initialization (prep) error rate + decompose_errors: If True (default), ask Stim to decompose hyperedge + errors into graphlike components. Set to False to preserve raw + hyperedges. + maximal_decomposition: If True, post-process Stim's graphlike output + into the same singleton-preferring maximal decomposition used by + the native DEM path. Ignored when False. Returns: DEM string in Stim format @@ -1407,9 +2100,11 @@ def generate_dem_from_tick_circuit_via_stim( msg = "Stim is required for this function. Install with: pip install stim" raise ImportError(msg) from e - stim_str = tick_circuit_to_stim(tc, p1=p1, p2=p2, p_meas=p_meas, p_init=p_init) + stim_str = tick_circuit_to_stim(tc, p1=p1, p2=p2, p_meas=p_meas, p_prep=p_prep) circuit = stim.Circuit(stim_str) - dem = circuit.detector_error_model(decompose_errors=True) + dem = circuit.detector_error_model(decompose_errors=decompose_errors or maximal_decomposition) + if maximal_decomposition: + return _maximally_decompose_graphlike_dem(str(dem)) return str(dem) @@ -1449,13 +2144,74 @@ def _extract_measurement_order(tc: TickCircuit) -> list[int]: return measurement_order +def get_measurement_order_from_tick_circuit(tc: TickCircuit) -> list[int]: + """Public wrapper returning the TickCircuit measurement execution order.""" + return _extract_measurement_order(tc) + + +def _maximally_decompose_graphlike_dem(dem_text: str) -> str: + """Prefer singleton graphlike components when the decomposed DEM exposes them. + + This is a formatting-level refinement over the standard decomposed DEM: + when a 2-detector direct mechanism `D_i D_j` has corresponding singleton + components already present in the DEM, prefer `D_i ^ D_j` (or the boundary + form `D_i L0 ^ D_j L0`) instead. + """ + standalone_detectors: set[str] = set() + det_l0_detectors: set[str] = set() + lines = dem_text.splitlines() + + for line in lines: + stripped = line.strip() + if not stripped.startswith("error("): + continue + payload = stripped.split(")", 1)[1].strip() + if "^" in payload: + continue + tokens = payload.split() + detectors = [token for token in tokens if token.startswith("D")] + logicals = [token for token in tokens if token.startswith("L")] + if len(detectors) == 1 and not logicals: + standalone_detectors.add(detectors[0]) + elif len(detectors) == 1 and logicals == ["L0"]: + det_l0_detectors.add(detectors[0]) + + rewritten_lines: list[str] = [] + for line in lines: + stripped = line.strip() + if not stripped.startswith("error("): + rewritten_lines.append(line) + continue + prefix, payload = stripped.split(")", 1) + payload = payload.strip() + if "^" in payload: + rewritten_lines.append(line) + continue + tokens = payload.split() + detectors = [token for token in tokens if token.startswith("D")] + logicals = [token for token in tokens if token.startswith("L")] + if len(detectors) == 2 and not logicals: + d0, d1 = detectors + replacement: str | None = None + if d0 in standalone_detectors and d1 in standalone_detectors: + replacement = f"{d0} ^ {d1}" + elif d0 in det_l0_detectors and d1 in det_l0_detectors: + replacement = f"{d0} L0 ^ {d1} L0" + if replacement is not None: + rewritten_lines.append(f"{prefix}) {replacement}") + continue + rewritten_lines.append(line) + + return "\n".join(rewritten_lines) + + def generate_dem_from_tick_circuit( tc: TickCircuit, *, p1: float = 0.01, p2: float = 0.01, p_meas: float = 0.01, - p_init: float = 0.01, + p_prep: float = 0.01, decompose_errors: bool = True, maximal_decomposition: bool = False, ) -> str: @@ -1482,7 +2238,7 @@ def generate_dem_from_tick_circuit( p1: Single-qubit depolarizing error rate p2: Two-qubit depolarizing error rate p_meas: Measurement error rate - p_init: Initialization (prep) error rate + p_prep: Initialization (prep) error rate decompose_errors: If True (default), decompose hyperedge errors into graphlike components using the `^` separator. Set to False to output raw hyperedges. Ignored if maximal_decomposition=True. @@ -1517,7 +2273,7 @@ def generate_dem_from_tick_circuit( # Build DEM using Rust DemBuilder builder = DemBuilder(influence_map) - builder.with_noise(p1, p2, p_meas, p_init) + builder.with_noise(p1, p2, p_meas, p_prep) builder.with_num_measurements(num_measurements) builder.with_measurement_order(measurement_order) builder.with_detectors_json(detectors_json) @@ -1526,8 +2282,9 @@ def generate_dem_from_tick_circuit( dem = builder.build_with_source_tracking() - # Use decomposed output if either decompose_errors or maximal_decomposition is set - if decompose_errors or maximal_decomposition: + if maximal_decomposition: + return _maximally_decompose_graphlike_dem(dem.to_string_decomposed()) + if decompose_errors: return dem.to_string_decomposed() return dem.to_string() @@ -1535,12 +2292,12 @@ def generate_dem_from_tick_circuit( def generate_dem_from_tick_circuit_via_autodetection( tc: TickCircuit, *, - logical_z_qubits: list[int] | None = None, - logical_x_qubits: list[int] | None = None, + tracked_z_qubits: list[int] | None = None, + tracked_x_qubits: list[int] | None = None, p1: float = 0.01, p2: float = 0.01, p_meas: float = 0.01, - p_init: float = 0.01, + p_prep: float = 0.01, ) -> str: """Generate DEM from TickCircuit using auto-discovered detectors. @@ -1554,17 +2311,20 @@ def generate_dem_from_tick_circuit_via_autodetection( Args: tc: TickCircuit (detector annotations not required) - logical_z_qubits: Qubit indices for logical Z operator (for X error tracking) - logical_x_qubits: Qubit indices for logical X operator (for Z error tracking) + tracked_z_qubits: Qubit indices for a tracked Z operator (for X error tracking) + tracked_x_qubits: Qubit indices for a tracked X operator (for Z error tracking) p1: Single-qubit depolarizing error rate p2: Two-qubit depolarizing error rate p_meas: Measurement error rate - p_init: Initialization (prep) error rate + p_prep: Initialization (prep) error rate Returns: - DEM string in Stim-compatible format + PECOS DEM string. With no tracked operators this is Stim-compatible; + tracked operators are represented with PECOS `pecos_tracked_op` + metadata lines. """ from collections import defaultdict + import json from pecos.qec import PAULI_X, PAULI_Y, PAULI_Z, InfluenceBuilder @@ -1573,18 +2333,17 @@ def generate_dem_from_tick_circuit_via_autodetection( # Build influence map with auto-discovered detectors builder = InfluenceBuilder(dag) - if logical_z_qubits: - builder.with_logical_z(logical_z_qubits) - if logical_x_qubits: - builder.with_logical_x(logical_x_qubits) + if tracked_x_qubits: + builder.with_tracked_x(tracked_x_qubits) + if tracked_z_qubits: + builder.with_tracked_z(tracked_z_qubits) influence_map = builder.build() # Get all fault locations and auto-discovered detectors locations = influence_map.get_locations() num_detectors = influence_map.num_detectors - num_logicals = influence_map.num_logicals - # Collect error mechanisms: (detectors, logicals) -> probability + # Collect error mechanisms: (detectors, DEM outputs) -> probability error_mechanisms: dict[tuple[frozenset[int], frozenset[int]], float] = defaultdict( float, ) @@ -1594,23 +2353,23 @@ def generate_dem_from_tick_circuit_via_autodetection( gate_type = loc.gate_type if "PZ" in gate_type or "QAlloc" in gate_type: - if p_init <= 0: + if p_prep <= 0: continue for pauli in [PAULI_X]: dets = set(influence_map.get_detector_indices(loc_idx, pauli)) - logs = set(influence_map.get_logical_indices(loc_idx, pauli)) - if dets or logs: - key = (frozenset(dets), frozenset(logs)) - error_mechanisms[key] += p_init + dem_outputs = set(influence_map.get_observable_indices(loc_idx, pauli)) + if dets or dem_outputs: + key = (frozenset(dets), frozenset(dem_outputs)) + error_mechanisms[key] += p_prep elif "MZ" in gate_type: if p_meas <= 0: continue for pauli in [PAULI_X]: dets = set(influence_map.get_detector_indices(loc_idx, pauli)) - logs = set(influence_map.get_logical_indices(loc_idx, pauli)) - if dets or logs: - key = (frozenset(dets), frozenset(logs)) + dem_outputs = set(influence_map.get_observable_indices(loc_idx, pauli)) + if dets or dem_outputs: + key = (frozenset(dets), frozenset(dem_outputs)) error_mechanisms[key] += p_meas elif "CX" in gate_type: @@ -1618,9 +2377,9 @@ def generate_dem_from_tick_circuit_via_autodetection( continue for pauli in [PAULI_X, PAULI_Y, PAULI_Z]: dets = set(influence_map.get_detector_indices(loc_idx, pauli)) - logs = set(influence_map.get_logical_indices(loc_idx, pauli)) - if dets or logs: - key = (frozenset(dets), frozenset(logs)) + dem_outputs = set(influence_map.get_observable_indices(loc_idx, pauli)) + if dets or dem_outputs: + key = (frozenset(dets), frozenset(dem_outputs)) error_mechanisms[key] += p2 / 3 elif "H" in gate_type: @@ -1628,27 +2387,53 @@ def generate_dem_from_tick_circuit_via_autodetection( continue for pauli in [PAULI_X, PAULI_Y, PAULI_Z]: dets = set(influence_map.get_detector_indices(loc_idx, pauli)) - logs = set(influence_map.get_logical_indices(loc_idx, pauli)) - if dets or logs: - key = (frozenset(dets), frozenset(logs)) + dem_outputs = set(influence_map.get_observable_indices(loc_idx, pauli)) + if dets or dem_outputs: + key = (frozenset(dets), frozenset(dem_outputs)) error_mechanisms[key] += p1 / 3 # Generate DEM output # Add detector declarations (auto-discovered, no coordinates) lines = [f"detector D{det_idx}" for det_idx in range(num_detectors)] - # Add logical observables - lines.extend(f"logical_observable L{log_idx}" for log_idx in range(num_logicals)) + def _pauli_string(pauli: str, qubits: list[int] | None) -> str: + if not qubits: + return "+I" + return "+" + " ".join(f"{pauli}{q}" for q in qubits) + + tracked_op_metadata = [] + if tracked_x_qubits: + tracked_op_metadata.append( + { + "id": len(tracked_op_metadata), + "kind": "tracked_operator", + "label": "tracked_x", + "pauli": _pauli_string("X", tracked_x_qubits), + } + ) + if tracked_z_qubits: + tracked_op_metadata.append( + { + "id": len(tracked_op_metadata), + "kind": "tracked_operator", + "label": "tracked_z", + "pauli": _pauli_string("Z", tracked_z_qubits), + } + ) + lines.extend( + f"pecos_tracked_op {json.dumps(metadata, separators=(',', ':'))}" + for metadata in tracked_op_metadata + ) # Add error mechanisms - for (dets, logs), prob in sorted( + for (dets, dem_outputs), prob in sorted( error_mechanisms.items(), key=lambda x: (sorted(x[0][0]), sorted(x[0][1])), ): - if prob > 0 and (dets or logs): + if prob > 0 and (dets or dem_outputs): det_str = " ".join(f"D{d}" for d in sorted(dets)) - log_str = " ".join(f"L{log_idx}" for log_idx in sorted(logs)) - targets = f"{det_str} {log_str}".strip() + dem_output_str = " ".join(f"L{idx}" for idx in sorted(dem_outputs)) + targets = f"{det_str} {dem_output_str}".strip() lines.append(f"error({prob:.6g}) {targets}") return "\n".join(lines) diff --git a/python/quantum-pecos/src/pecos/qec/surface/circuit_gen.py b/python/quantum-pecos/src/pecos/qec/surface/circuit_gen.py index ff69a0ab6..0886f965e 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/circuit_gen.py +++ b/python/quantum-pecos/src/pecos/qec/surface/circuit_gen.py @@ -33,7 +33,7 @@ def generate_stim_circuit( p1: float = 0.0, p2: float = 0.0, p_meas: float = 0.0, - p_init: float = 0.0, + p_prep: float = 0.0, ) -> str: """Generate a Stim circuit from SurfacePatch geometry. @@ -53,7 +53,7 @@ def generate_stim_circuit( p1: Single-qubit gate depolarizing error rate p2: Two-qubit gate depolarizing error rate p_meas: Measurement error rate (X_ERROR before M) - p_init: Initialization error rate (X_ERROR after R) + p_prep: Initialization error rate (X_ERROR after R) Returns: Stim circuit string with noise and detector annotations @@ -109,8 +109,8 @@ def z_anc_q(stab_idx: int) -> int: # Allocate data qubits (R = reset = qubit()) for i in range(num_data): lines.append(f"R {data_q(i)}") - if p_init > 0: - lines.append(f"X_ERROR({p_init}) {data_q(i)}") + if p_prep > 0: + lines.append(f"X_ERROR({p_prep}) {data_q(i)}") # For X-basis: H on each data qubit if basis.upper() == "X": @@ -140,14 +140,14 @@ def z_anc_q(stab_idx: int) -> int: # Guppy: ax{i} = qubit() for each X stabilizer for s in geom.x_stabilizers: lines.append(f"R {x_anc_q(s.index)}") - if p_init > 0: - lines.append(f"X_ERROR({p_init}) {x_anc_q(s.index)}") + if p_prep > 0: + lines.append(f"X_ERROR({p_prep}) {x_anc_q(s.index)}") # Guppy: az{i} = qubit() for each Z stabilizer for s in geom.z_stabilizers: lines.append(f"R {z_anc_q(s.index)}") - if p_init > 0: - lines.append(f"X_ERROR({p_init}) {z_anc_q(s.index)}") + if p_prep > 0: + lines.append(f"X_ERROR({p_prep}) {z_anc_q(s.index)}") lines.append("") @@ -341,7 +341,7 @@ def generate_circuit_level_dem( p1=p, p2=p, p_meas=p, - p_init=p, + p_prep=p, ) # Parse and generate DEM @@ -474,7 +474,7 @@ def compare_dems( stim_dem = generate_circuit_level_dem(patch, num_rounds, basis, p=p) # Generate phenomenological DEM - noise = NoiseModel(p1=p, p2=p, p_meas=p, p_init=p) + noise = NoiseModel(p1=p, p2=p, p_meas=p, p_prep=p) stab_type = "X" if basis.upper() == "X" else "Z" phenom_dem = generate_surface_code_dem(patch, num_rounds, noise, stab_type) diff --git a/python/quantum-pecos/src/pecos/qec/surface/decode.py b/python/quantum-pecos/src/pecos/qec/surface/decode.py index e75fd7034..526190f86 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/decode.py +++ b/python/quantum-pecos/src/pecos/qec/surface/decode.py @@ -45,6 +45,7 @@ from dataclasses import dataclass from enum import Enum +from functools import cache from typing import TYPE_CHECKING, Any, Literal import numpy as np @@ -52,7 +53,6 @@ if TYPE_CHECKING: import stim from numpy.typing import NDArray - from pecos_rslib.qec import MeasurementNoiseModel from pecos.qec.surface.patch import Stabilizer, SurfacePatch @@ -70,32 +70,47 @@ class DecoderType(str, Enum): @dataclass class NoiseModel: - """Depolarizing noise parameters for surface code simulation. + """Circuit-level noise parameters for QEC simulation. - These parameters match the DepolarizingErrorModel in selene_sim. + Matches the Rust ``NoiseConfig`` type. All parameters are optional + beyond the four base rates. Attributes: - p1: Single-qubit gate error rate - p2: Two-qubit gate error rate - p_meas: Measurement error rate - p_init: Initialization error rate + p1: Single-qubit gate error rate. + p2: Two-qubit gate error rate. + p_meas: Measurement error rate. + p_prep: Initialization error rate. + p_idle: Idle noise rate per time unit (uniform depolarizing). + t1: T1 relaxation time for idle noise (same units as idle duration). + t2: T2 dephasing time (must satisfy t2 <= 2*t1). """ - p1: float = 0.0 # Single-qubit gate error rate - p2: float = 0.0 # Two-qubit gate error rate - p_meas: float = 0.0 # Measurement error rate - p_init: float = 0.0 # Initialization error rate + p1: float = 0.0 + p2: float = 0.0 + p_meas: float = 0.0 + p_prep: float = 0.0 + p_idle: float | None = None + t1: float | None = None + t2: float | None = None @property def is_noiseless(self) -> bool: """True if all error rates are zero.""" - return self.p1 == 0.0 and self.p2 == 0.0 and self.p_meas == 0.0 and self.p_init == 0.0 + return ( + self.p1 == 0.0 + and self.p2 == 0.0 + and self.p_meas == 0.0 + and self.p_prep == 0.0 + and (self.p_idle is None or self.p_idle == 0.0) + ) @property def physical_error_rate(self) -> float: - """Approximate combined physical error rate (for DEM weights).""" - # Use maximum as a conservative estimate - return max(self.p1, self.p2, self.p_meas, self.p_init) + """Approximate combined physical error rate.""" + rates = [self.p1, self.p2, self.p_meas, self.p_prep] + if self.p_idle is not None: + rates.append(self.p_idle) + return max(rates) @dataclass @@ -109,6 +124,43 @@ class DecodingResult: decoding_weight: float # Weight of the matching solution +@dataclass(frozen=True) +class _CachedNativeSurfaceTopology: + """Topology-only native model data reused across noise configurations.""" + + influence_map: Any + detectors_json: str + observables_json: str + measurement_order: tuple[int, ...] + num_measurements: int + num_detectors: int + num_observables: int + + +def _surface_patch_cache_key(patch: SurfacePatch) -> tuple[int, int, str, bool]: + """Create a stable cache key for surface-patch topology.""" + return ( + patch.dx, + patch.dz, + patch.geometry.orientation.name, + patch.geometry.rotated, + ) + + +@cache +def _cached_surface_patch(patch_key: tuple[int, int, str, bool]) -> SurfacePatch: + """Recreate a canonical patch from a geometry cache key.""" + from pecos.qec.surface.patch import PatchOrientation, SurfacePatch + + dx, dz, orientation_name, rotated = patch_key + return SurfacePatch.create( + dx=dx, + dz=dz, + orientation=PatchOrientation[orientation_name], + rotated=rotated, + ) + + def syndromes_to_detection_events( syndromes: NDArray[np.uint8], num_rounds: int, @@ -322,11 +374,638 @@ def det_id(round_: int, stab_idx: int) -> int: return "\n".join(lines) +def _copy_surface_tick_circuit_metadata(source_tc: Any, target_tc: Any) -> None: + """Copy the surface-level metadata needed by the native DEM/sampler builders.""" + for key in ( + "basis", + "detectors", + "observables", + "num_measurements", + "num_detectors", + "detector_descriptors", + "observable_descriptors", + ): + value = source_tc.get_meta(key) + if value is not None: + target_tc.set_meta(key, value) + + +def _replay_qis_trace_into_tick_circuit(operations: list[dict[str, Any]]) -> Any: + """Replay traced QIS operations into a PECOS TickCircuit.""" + import heapq + + from pecos_rslib.quantum import TickCircuit + + tick_circuit = TickCircuit() + active_slots: dict[int, int] = {} + free_slots: list[int] = [] + next_slot = 0 + + def allocate_slot(program_id: int) -> int: + nonlocal next_slot + if program_id in active_slots: + return active_slots[program_id] + if free_slots: + slot = heapq.heappop(free_slots) + else: + slot = next_slot + next_slot += 1 + active_slots[program_id] = slot + return slot + + def release_slot(program_id: int) -> None: + slot = active_slots.pop(program_id, None) + if slot is not None: + heapq.heappush(free_slots, slot) + + def mapped_slot(program_id: int, op_name: str) -> int: + if program_id not in active_slots: + msg = f"Traced QIS op {op_name!r} referenced unmapped program qubit {program_id}" + raise ValueError(msg) + return active_slots[program_id] + + def scalar_arg(payload: Any, op_name: str) -> int: + if isinstance(payload, list): + msg = f"Expected scalar payload for {op_name}, got {payload!r}" + raise TypeError(msg) + return int(payload) + + def tuple_args(payload: Any, op_name: str, arity: int) -> tuple[Any, ...]: + if not isinstance(payload, list) or len(payload) != arity: + msg = f"Expected {arity} arguments for {op_name}, got {payload!r}" + raise ValueError(msg) + return tuple(payload) + + for operation in operations: + if "AllocateQubit" in operation: + program_id = int(operation["AllocateQubit"]["id"]) + slot = allocate_slot(program_id) + tick_circuit.tick().pz([slot]) + continue + + if "ReleaseQubit" in operation: + release_slot(int(operation["ReleaseQubit"]["id"])) + continue + + if "AllocateResult" in operation or "RecordOutput" in operation or "Barrier" in operation: + continue + + quantum = operation.get("Quantum") + if quantum is None or len(quantum) != 1: + msg = f"Unsupported traced operation payload: {operation!r}" + raise ValueError(msg) + + op_name, payload = next(iter(quantum.items())) + tick = tick_circuit.tick() + + if op_name == "H": + tick.h([mapped_slot(scalar_arg(payload, op_name), op_name)]) + elif op_name == "X": + tick.x([mapped_slot(scalar_arg(payload, op_name), op_name)]) + elif op_name == "Y": + tick.y([mapped_slot(scalar_arg(payload, op_name), op_name)]) + elif op_name == "Z": + tick.z([mapped_slot(scalar_arg(payload, op_name), op_name)]) + elif op_name == "S": + tick.sz([mapped_slot(scalar_arg(payload, op_name), op_name)]) + elif op_name == "Sdg": + tick.szdg([mapped_slot(scalar_arg(payload, op_name), op_name)]) + elif op_name == "T": + tick.t([mapped_slot(scalar_arg(payload, op_name), op_name)]) + elif op_name == "Tdg": + tick.tdg([mapped_slot(scalar_arg(payload, op_name), op_name)]) + elif op_name == "RX": + theta, program_id = tuple_args(payload, op_name, 2) + tick.rx(float(theta), [mapped_slot(int(program_id), op_name)]) + elif op_name == "RY": + theta, program_id = tuple_args(payload, op_name, 2) + tick.ry(float(theta), [mapped_slot(int(program_id), op_name)]) + elif op_name == "RZ": + theta, program_id = tuple_args(payload, op_name, 2) + tick.rz(float(theta), [mapped_slot(int(program_id), op_name)]) + elif op_name == "RXY": + theta, phi, program_id = tuple_args(payload, op_name, 3) + tick.r1xy(float(theta), float(phi), [mapped_slot(int(program_id), op_name)]) + elif op_name == "CX": + control, target = tuple_args(payload, op_name, 2) + tick.cx([(mapped_slot(int(control), op_name), mapped_slot(int(target), op_name))]) + elif op_name == "CY": + control, target = tuple_args(payload, op_name, 2) + tick.cy([(mapped_slot(int(control), op_name), mapped_slot(int(target), op_name))]) + elif op_name == "CZ": + control, target = tuple_args(payload, op_name, 2) + tick.cz([(mapped_slot(int(control), op_name), mapped_slot(int(target), op_name))]) + elif op_name == "CH": + control, target = tuple_args(payload, op_name, 2) + tick.ch([(mapped_slot(int(control), op_name), mapped_slot(int(target), op_name))]) + elif op_name == "CRZ": + theta, control, target = tuple_args(payload, op_name, 3) + tick.crz( + float(theta), + [(mapped_slot(int(control), op_name), mapped_slot(int(target), op_name))], + ) + elif op_name == "CCX": + control_a, control_b, target = tuple_args(payload, op_name, 3) + tick.ccx( + [ + ( + mapped_slot(int(control_a), op_name), + mapped_slot(int(control_b), op_name), + mapped_slot(int(target), op_name), + ), + ], + ) + elif op_name == "ZZ": + qubit_a, qubit_b = tuple_args(payload, op_name, 2) + tick.szz([(mapped_slot(int(qubit_a), op_name), mapped_slot(int(qubit_b), op_name))]) + elif op_name == "RZZ": + theta, qubit_a, qubit_b = tuple_args(payload, op_name, 3) + tick.rzz( + float(theta), + [(mapped_slot(int(qubit_a), op_name), mapped_slot(int(qubit_b), op_name))], + ) + elif op_name == "Measure": + program_id, _result_id = tuple_args(payload, op_name, 2) + tick.mz([mapped_slot(int(program_id), op_name)]) + elif op_name == "Reset": + tick.pz([mapped_slot(scalar_arg(payload, op_name), op_name)]) + else: + msg = f"Unsupported traced QIS quantum op {op_name!r}" + raise ValueError(msg) + + # Compact: ASAP-schedule gates into minimal ticks + tick_circuit.compact_ticks() + + return tick_circuit + + +def _gate_pairs(qubits: list[int], gate_type: str) -> list[tuple[int, int]]: + """Convert a flattened qubit list into disjoint qubit pairs.""" + if len(qubits) % 2 != 0: + msg = f"Lowered gate {gate_type!r} expected an even number of qubits, got {qubits!r}" + raise ValueError(msg) + return list(zip(qubits[::2], qubits[1::2], strict=True)) + + +def _gate_triples(qubits: list[int], gate_type: str) -> list[tuple[int, int, int]]: + """Convert a flattened qubit list into disjoint qubit triples.""" + if len(qubits) % 3 != 0: + msg = f"Lowered gate {gate_type!r} expected qubits in triples, got {qubits!r}" + raise ValueError(msg) + return [(qubits[i], qubits[i + 1], qubits[i + 2]) for i in range(0, len(qubits), 3)] + + +def _replay_lowered_qis_trace_into_tick_circuit(chunks: list[dict[str, Any]]) -> Any: + """Replay lowered post-Selene ByteMessage gate batches into a TickCircuit. + + The lowered trace emits gates one at a time. We replay each into its own + tick, then compact (ASAP schedule) so that gates on disjoint qubits share + a tick --- matching the parallel structure of the abstract circuit. + + MeasIds flow from Guppy result() objects: AllocateResult IDs from the + operations stream are stamped on MZ gates via mz_with_ids(). + """ + from pecos_rslib.quantum import TickCircuit + + tick_circuit = TickCircuit() + + for chunk in chunks: + # Extract AllocateResult ID → MZ qubit mapping from the operations stream. + # Each AllocateResult(id=N) is followed by Quantum.Measure([qubit, slot]). + # This gives us the MeasId to stamp on each MZ gate. + meas_id_queue: list[tuple[int, int]] = [] # (qubit, meas_id) pairs + last_alloc_id: int | None = None + for op in chunk.get("operations") or []: + op_dict = dict(op) + if "AllocateResult" in op_dict: + last_alloc_id = int(op_dict["AllocateResult"]["id"]) + elif "Quantum" in op_dict: + q_op = op_dict["Quantum"] + if "Measure" in q_op and last_alloc_id is not None: + qubit = int(q_op["Measure"][0]) + meas_id_queue.append((qubit, last_alloc_id)) + last_alloc_id = None + + meas_id_idx = 0 # next MeasId to assign + + for gate in chunk.get("lowered_quantum_ops") or []: + gate_type = str(gate["gate_type"]) + qubits = [int(q) for q in gate.get("qubits", [])] + angles = [float(theta) for theta in gate.get("angles", [])] + tick = tick_circuit.tick() + + if gate_type == "H": + tick.h(qubits) + elif gate_type == "X": + tick.x(qubits) + elif gate_type == "Y": + tick.y(qubits) + elif gate_type == "Z": + tick.z(qubits) + elif gate_type == "SZ": + tick.sz(qubits) + elif gate_type == "SZdg": + tick.szdg(qubits) + elif gate_type == "T": + tick.t(qubits) + elif gate_type == "Tdg": + tick.tdg(qubits) + elif gate_type == "PZ": + tick.pz(qubits) + elif gate_type == "MZ": + # Stamp MeasIds from the AllocateResult stream + meas_ids = [] + for q in qubits: + if meas_id_idx < len(meas_id_queue): + expected_q, mid = meas_id_queue[meas_id_idx] + if expected_q == q: + meas_ids.append(mid) + meas_id_idx += 1 + else: + # Qubit mismatch — fall back to auto-assign + meas_ids = [] + break + else: + meas_ids = [] + break + + if meas_ids: + tick.mz_with_ids(qubits, meas_ids) + else: + tick.mz(qubits) + elif gate_type == "RX": + tick.rx(angles[0], qubits) + elif gate_type == "RY": + tick.ry(angles[0], qubits) + elif gate_type == "RZ": + tick.rz(angles[0], qubits) + elif gate_type == "R1XY": + tick.r1xy(angles[0], angles[1], qubits) + elif gate_type == "CX": + tick.cx(_gate_pairs(qubits, gate_type)) + elif gate_type == "CY": + tick.cy(_gate_pairs(qubits, gate_type)) + elif gate_type == "CZ": + tick.cz(_gate_pairs(qubits, gate_type)) + elif gate_type == "CH": + tick.ch(_gate_pairs(qubits, gate_type)) + elif gate_type == "CRZ": + tick.crz(angles[0], _gate_pairs(qubits, gate_type)) + elif gate_type == "SZZ": + tick.szz(_gate_pairs(qubits, gate_type)) + elif gate_type == "SZZdg": + tick.szzdg(_gate_pairs(qubits, gate_type)) + elif gate_type == "RZZ": + tick.rzz(angles[0], _gate_pairs(qubits, gate_type)) + elif gate_type == "CCX": + tick.ccx(_gate_triples(qubits, gate_type)) + else: + msg = f"Unsupported lowered traced gate {gate_type!r}" + raise ValueError(msg) + + # Compact: ASAP-schedule gates into minimal ticks + tick_circuit.compact_ticks() + + return tick_circuit + + +def _generate_traced_surface_tick_circuit( + patch: SurfacePatch, + num_rounds: int, + basis: str, +) -> Any: + """Trace the lowered ideal Selene/QIS op stream and replay it into a TickCircuit.""" + import pecos + from pecos.guppy import get_num_qubits, make_surface_code + + program = make_surface_code(distance=patch.distance, num_rounds=num_rounds, basis=basis) + sim_builder = ( + pecos.sim(program) + .classical(pecos.selene_engine()) + .quantum(pecos.stabilizer()) + .qubits(get_num_qubits(patch.distance)) + .seed(0) + ) + chunks = list(sim_builder.capture_operation_trace()) + + if any(chunk.get("lowered_quantum_ops") for chunk in chunks): + return _replay_lowered_qis_trace_into_tick_circuit(chunks) + + operations: list[dict[str, Any]] = [] + for chunk in chunks: + operations.extend(list(chunk.get("operations", []))) + return _replay_qis_trace_into_tick_circuit(operations) + + +def _build_surface_tick_circuit_for_native_model( + patch: SurfacePatch, + num_rounds: int, + basis: str, + *, + ancilla_budget: int | None = None, + circuit_source: Literal["abstract", "traced_qis"] = "abstract", +) -> Any: + """Build the TickCircuit used by the native DEM and sampler paths.""" + from pecos.qec.surface.circuit_builder import ( + _extract_measurement_order, + generate_tick_circuit_from_patch, + ) + + abstract_tc = generate_tick_circuit_from_patch( + patch, + num_rounds, + basis, + ancilla_budget=ancilla_budget, + ) + + if circuit_source == "abstract": + return abstract_tc + + if circuit_source != "traced_qis": + msg = f"Unknown circuit_source {circuit_source!r}" + raise ValueError(msg) + + if ancilla_budget is not None: + msg = ( + "circuit_source='traced_qis' does not currently support ancilla_budget because " + "pecos.guppy.surface.make_surface_code does not yet expose ancilla budgeting" + ) + raise ValueError(msg) + + traced_tc = _generate_traced_surface_tick_circuit(patch, num_rounds, basis) + traced_measurement_order = _extract_measurement_order(traced_tc) + abstract_measurement_order = _extract_measurement_order(abstract_tc) + if traced_measurement_order != abstract_measurement_order: + msg = ( + "Lowered traced circuit measurement order does not match the abstract surface " + "metadata; refusing to build a mismatched native DEM/sampler" + ) + raise ValueError(msg) + + _copy_surface_tick_circuit_metadata(abstract_tc, traced_tc) + traced_tc.set_meta("circuit_source", circuit_source) + return traced_tc + + +def _can_use_cached_surface_topology( + *, + ancilla_budget: int | None, +) -> bool: + """Return True when we can safely use the shared native topology cache.""" + return ancilla_budget is None + + +@cache +def _cached_surface_native_topology( + patch_key: tuple[int, int, str, bool], + num_rounds: int, + basis: str, + ancilla_budget: int | None, + circuit_source: Literal["abstract", "traced_qis"], +) -> _CachedNativeSurfaceTopology: + """Cache topology-only native analysis shared across noise parameters.""" + import json + + from pecos.qec import DagFaultAnalyzer + from pecos.qec.surface.circuit_builder import _extract_measurement_order + + patch = _cached_surface_patch(patch_key) + tc = _build_surface_tick_circuit_for_native_model( + patch, + num_rounds, + basis, + ancilla_budget=ancilla_budget, + circuit_source=circuit_source, + ) + # Insert idle gates so non-active qubits get noise in the after-only model. + # Note: the traced circuit has one gate per tick (fully serialized). + # Call tc.compact_ticks() before this to merge parallel gates into + # shared ticks if the hardware model supports parallel execution. + tc.fill_idle_gates() + + dag = tc.to_dag_circuit() + analyzer = DagFaultAnalyzer(dag) + influence_map = analyzer.build_influence_map() + + detectors_json = tc.get_meta("detectors") or "[]" + observables_json = tc.get_meta("observables") or "[]" + measurement_order = tuple(_extract_measurement_order(tc)) + num_measurements = int(tc.get_meta("num_measurements") or str(len(measurement_order))) + + return _CachedNativeSurfaceTopology( + influence_map=influence_map, + detectors_json=detectors_json, + observables_json=observables_json, + measurement_order=measurement_order, + num_measurements=num_measurements, + num_detectors=len(json.loads(detectors_json)) if detectors_json else 0, + num_observables=len(json.loads(observables_json)) if observables_json else 0, + ) + + +def _dem_string_from_cached_surface_topology( + topology: _CachedNativeSurfaceTopology, + noise: NoiseModel, + *, + decompose_errors: bool, +) -> str: + """Build a DEM string from cached topology and fresh noise parameters.""" + from pecos.qec import DemBuilder + + dem = ( + DemBuilder(topology.influence_map) + .with_noise(noise.p1, noise.p2, noise.p_meas, noise.p_prep, p_idle=noise.p_idle, t1=noise.t1, t2=noise.t2) + .with_num_measurements(topology.num_measurements) + .with_measurement_order(list(topology.measurement_order)) + .with_detectors_json(topology.detectors_json) + .with_observables_json(topology.observables_json) + .build_with_source_tracking() + ) + return dem.to_string_decomposed() if decompose_errors else dem.to_string() + + +@cache +def _cached_surface_native_dem_string( + patch_key: tuple[int, int, str, bool], + num_rounds: int, + basis: str, + ancilla_budget: int | None, + circuit_source: Literal["abstract", "traced_qis"], + p1: float, + p2: float, + p_meas: float, + p_prep: float, + decompose_errors: bool, + p_idle: float | None = None, + t1: float | None = None, + t2: float | None = None, +) -> str: + """Cache native DEM strings across callers for one topology + noise tuple.""" + topology = _cached_surface_native_topology( + patch_key, + num_rounds, + basis, + ancilla_budget, + circuit_source, + ) + return _dem_string_from_cached_surface_topology( + topology, + NoiseModel(p1=p1, p2=p2, p_meas=p_meas, p_prep=p_prep, p_idle=p_idle, t1=t1, t2=t2), + decompose_errors=decompose_errors, + ) + + +@cache +def _cached_parsed_dem(dem_str: str) -> Any: + """Cache parsed DEM objects so repeated sampler builds only instantiate the sampler.""" + from pecos.qec import ParsedDem + + return ParsedDem.from_string(dem_str) + + +def _build_native_sampler_from_cached_surface_topology( + topology: _CachedNativeSurfaceTopology, + noise: NoiseModel, + *, + sampling_model: Literal[ + "dem", + "influence_dem", + "mnm", + ] = "dem", # "mnm" accepted for compat, mapped to "influence_dem", +) -> NativeSampler: + """Construct a native sampler from cached topology-only analysis.""" + from pecos.qec import DemSampler, ParsedDem + + if sampling_model == "dem": + dem_str = _dem_string_from_cached_surface_topology( + topology, + noise, + decompose_errors=True, + ) + sampler = ParsedDem.from_string(dem_str).to_dem_sampler() + elif sampling_model in ("influence_dem", "mnm"): + import json + + det_records = [d["records"] for d in json.loads(topology.detectors_json)] + obs_records = [o["records"] for o in json.loads(topology.observables_json)] if topology.observables_json else [] + sampler = DemSampler.with_detectors( + topology.influence_map, + det_records, + obs_records, + noise.p1, + noise.p2, + noise.p_meas, + noise.p_prep, + p_idle=noise.p_idle, + t1=noise.t1, + t2=noise.t2, + ) + # Remap sampling_model for NativeSampler dispatch + sampling_model = "influence_dem" + else: + msg = f"Unknown native sampling_model {sampling_model!r}" + raise ValueError(msg) + + return NativeSampler( + sampler=sampler, + detectors_json=topology.detectors_json, + observables_json=topology.observables_json, + num_detectors=topology.num_detectors, + num_observables=topology.num_observables, + sampling_model=sampling_model, + ) + + +def _build_native_sampler_from_tick_circuit( + tc: Any, + noise: NoiseModel, + *, + sampling_model: Literal[ + "dem", + "influence_dem", + "mnm", + ] = "dem", # "mnm" accepted for compat, mapped to "influence_dem", +) -> NativeSampler: + """Construct a native sampler directly from a TickCircuit.""" + import json + + from pecos.qec import DagFaultAnalyzer, DemSampler, ParsedDem + from pecos.qec.surface.circuit_builder import generate_dem_from_tick_circuit + + # Insert idle gates for qubits not active during each tick. + # This is critical: without idle gates, qubits sitting idle between + # operations get no noise in the after-only fault model. + tc.fill_idle_gates() + + dag = tc.to_dag_circuit() + analyzer = DagFaultAnalyzer(dag) + influence_map = analyzer.build_influence_map() + + detectors_json = tc.get_meta("detectors") or "[]" + observables_json = tc.get_meta("observables") or "[]" + num_detectors = len(json.loads(detectors_json)) if detectors_json else 0 + num_observables = len(json.loads(observables_json)) if observables_json else 0 + + if sampling_model == "dem": + dem_str = generate_dem_from_tick_circuit( + tc, + p1=noise.p1, + p2=noise.p2, + p_meas=noise.p_meas, + p_prep=noise.p_prep, + decompose_errors=True, + ) + sampler = ParsedDem.from_string(dem_str).to_dem_sampler() + elif sampling_model in ("influence_dem", "mnm"): + det_records = [d["records"] for d in json.loads(detectors_json)] + obs_records = [o["records"] for o in json.loads(observables_json)] if observables_json else [] + sampler = DemSampler.with_detectors( + influence_map, + det_records, + obs_records, + noise.p1, + noise.p2, + noise.p_meas, + noise.p_prep, + p_idle=noise.p_idle, + t1=noise.t1, + t2=noise.t2, + ) + sampling_model = "influence_dem" + elif sampling_model == "from_circuit": + # Direct from_circuit path: uses DagCircuit annotations and + # handles idle noise automatically via NoiseConfig. + sampler = DemSampler.from_circuit( + dag, + p1=noise.p1, + p2=noise.p2, + p_meas=noise.p_meas, + p_prep=noise.p_prep, + p_idle=noise.p_idle, + ) + else: + msg = f"Unknown native sampling_model {sampling_model!r}" + raise ValueError(msg) + + return NativeSampler( + sampler=sampler, + detectors_json=detectors_json, + observables_json=observables_json, + num_detectors=num_detectors, + num_observables=num_observables, + sampling_model=sampling_model, + ) + + def generate_circuit_level_dem_from_builder( patch: SurfacePatch, num_rounds: int, noise: NoiseModel, basis: str = "Z", + *, + decompose_errors: bool = False, + ancilla_budget: int | None = None, + circuit_source: Literal["abstract", "traced_qis"] = "abstract", ) -> str: """Generate circuit-level DEM using PECOS native fault propagation. @@ -344,6 +1023,17 @@ def generate_circuit_level_dem_from_builder( num_rounds: Number of syndrome extraction rounds noise: Noise model parameters basis: Memory basis ('X' or 'Z') + decompose_errors: If True, return PECOS's native decomposed DEM + representation, which is more appropriate for graph-based + decoders like PyMatching. + ancilla_budget: Optional cap on simultaneously live ancillas. When + provided below the total stabilizer count, the native DEM is built + from the same batched ancilla-reuse circuit family used by Guppy. + circuit_source: Which ideal circuit to analyze for the native DEM path. + ``"abstract"`` uses the existing high-level surface TickCircuit. + ``"traced_qis"`` traces the lowered ideal Selene/QIS gate stream + and replays that exact gate list into a TickCircuit before running + native PECOS fault analysis. Returns: DEM string in standard format @@ -355,37 +1045,41 @@ def generate_circuit_level_dem_from_builder( >>> noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.01) >>> dem = generate_circuit_level_dem_from_builder(patch, num_rounds=3, noise=noise) """ - from pecos.qec import DagFaultAnalyzer, DemBuilder - from pecos.qec.surface.circuit_builder import ( - _extract_measurement_order, - generate_tick_circuit_from_patch, - ) - - # Generate TickCircuit (source of truth for circuit structure) - tc = generate_tick_circuit_from_patch(patch, num_rounds, basis) - - # Convert to DAG and build influence map via Rust fault propagation - dag = tc.to_dag_circuit() - analyzer = DagFaultAnalyzer(dag) - influence_map = analyzer.build_influence_map() - - # Extract metadata from TickCircuit - detectors_json = tc.get_meta("detectors") - observables_json = tc.get_meta("observables") - num_measurements = int(tc.get_meta("num_measurements") or "0") - measurement_order = _extract_measurement_order(tc) - - # Build DEM using native PECOS builder - builder = DemBuilder(influence_map) - builder.with_noise(noise.p1, noise.p2, noise.p_meas, noise.p_init) - builder.with_num_measurements(num_measurements) - builder.with_measurement_order(measurement_order) - builder.with_detectors_json(detectors_json) - if observables_json: - builder.with_observables_json(observables_json) + from pecos.qec.surface.circuit_builder import generate_dem_from_tick_circuit + + if _can_use_cached_surface_topology(ancilla_budget=ancilla_budget): + patch_key = _surface_patch_cache_key(patch) + return _cached_surface_native_dem_string( + patch_key, + num_rounds, + basis.upper(), + ancilla_budget, + circuit_source, + noise.p1, + noise.p2, + noise.p_meas, + noise.p_prep, + decompose_errors=decompose_errors, + p_idle=noise.p_idle, + t1=noise.t1, + t2=noise.t2, + ) - dem = builder.build() - return dem.to_string() + tc = _build_surface_tick_circuit_for_native_model( + patch, + num_rounds, + basis, + ancilla_budget=ancilla_budget, + circuit_source=circuit_source, + ) + return generate_dem_from_tick_circuit( + tc, + p1=noise.p1, + p2=noise.p2, + p_meas=noise.p_meas, + p_prep=noise.p_prep, + decompose_errors=decompose_errors, + ) def generate_circuit_level_dem( @@ -435,7 +1129,7 @@ def generate_circuit_level_dem( rounds=num_rounds, after_clifford_depolarization=noise.p2 if noise.p2 > 0 else 0.0, before_measure_flip_probability=noise.p_meas if noise.p_meas > 0 else 0.0, - after_reset_flip_probability=noise.p_init if noise.p_init > 0 else 0.0, + after_reset_flip_probability=noise.p_prep if noise.p_prep > 0 else 0.0, ) # Generate DEM from circuit @@ -691,6 +1385,8 @@ def generate_dem_from_patch( num_rounds: int, noise: NoiseModel, basis: str = "Z", + *, + decompose_errors: bool = True, ) -> str: """Generate a circuit-level DEM from our patch geometry. @@ -704,6 +1400,8 @@ def generate_dem_from_patch( num_rounds: Number of syndrome extraction rounds noise: Noise model parameters basis: Memory basis ('X' or 'Z') + decompose_errors: If True, return Stim's decomposed graphlike DEM. + If False, return the raw hypergraph DEM. Returns: DEM string in Stim format @@ -719,7 +1417,7 @@ def generate_dem_from_patch( >>> dem = generate_dem_from_patch(patch, num_rounds=3, noise=noise) """ circuit = build_stim_circuit_from_patch(patch, num_rounds, noise, basis) - dem = circuit.detector_error_model(decompose_errors=True) + dem = circuit.detector_error_model(decompose_errors=decompose_errors) return str(dem) @@ -756,6 +1454,9 @@ def __init__( ] = "pymatching", *, use_circuit_level_dem: bool = True, + circuit_level_dem_mode: Literal["native_full", "native_decomposed"] = "native_full", + circuit_level_dem_source: Literal["abstract", "traced_qis"] = "abstract", + ancilla_budget: int | None = None, ) -> None: """Initialize decoder from surface code patch. @@ -775,12 +1476,28 @@ def __init__( This provides proper error propagation through gates matching the actual Guppy/Selene circuits. If False, use phenomenological DEMs or check matrices. + circuit_level_dem_mode: Which PECOS-native DEM representation to use + when circuit-level DEMs are enabled. ``"native_full"`` preserves + the current non-decomposed DEM output. ``"native_decomposed"`` + returns PECOS's graphlike decomposed DEM output, which is often + a better fit for graph decoders such as PyMatching. + circuit_level_dem_source: Which ideal circuit to analyze when + building native circuit-level DEMs. ``"abstract"`` uses the + high-level surface TickCircuit, while ``"traced_qis"`` traces + the lowered ideal Selene/QIS gate stream and analyzes that. + ancilla_budget: Optional cap on simultaneously live ancillas for + the native circuit-level DEM path. When provided, the decoder + builds its DEM from the corresponding batched ancilla-reuse + circuit instead of the default dedicated-ancilla circuit. """ self.patch = patch self.num_rounds = num_rounds self.noise = noise or NoiseModel(p2=0.01, p_meas=0.01) self.decoder_type = DecoderType(decoder_type) self.use_circuit_level_dem = use_circuit_level_dem + self.circuit_level_dem_mode = circuit_level_dem_mode + self.circuit_level_dem_source = circuit_level_dem_source + self.ancilla_budget = ancilla_budget # Lazily create decoders self._x_decoder = None @@ -809,12 +1526,20 @@ def _get_circuit_level_dem(self, basis: str) -> str: Returns: DEM string in Stim format """ - return generate_circuit_level_dem_from_builder( + dem = generate_circuit_level_dem_from_builder( self.patch, self.num_rounds, self.noise, basis=basis, + decompose_errors=self.circuit_level_dem_mode == "native_decomposed", + circuit_source=self.circuit_level_dem_source, + ancilla_budget=self.ancilla_budget, ) + if basis.upper() == "Z": + self._z_dem = dem + else: + self._x_dem = dem + return dem def _get_z_check_matrix(self) -> NDArray[np.uint8]: """Get Z stabilizer parity check matrix.""" @@ -1541,6 +2266,67 @@ def decode_memory_x( return is_logical_error, result + def _get_css_uf_decoder(self): + """Get or create the UIUF CSS UF decoder.""" + if not hasattr(self, "_css_uf_decoder") or self._css_uf_decoder is None: + from pecos_rslib.qec import CssUfDecoder + + x_dem = self.get_dem("X", circuit_level=True) + z_dem = self.get_dem("Z", circuit_level=True) + # Strip logical_observable lines (not needed for matching graph). + x_dem = "\n".join(line for line in x_dem.split("\n") if not line.startswith("logical_observable")) + z_dem = "\n".join(line for line in z_dem.split("\n") if not line.startswith("logical_observable")) + self._css_uf_decoder = CssUfDecoder(x_dem, z_dem) + return self._css_uf_decoder + + def decode_memory_z_uiuf( + self, + synx_list: list, + synz_list: list, + final, + ) -> tuple[bool, DecodingResult]: + """Decode Z-basis memory using UIUF (joint X/Z intersection). + + Like ``decode_memory_z`` but uses both X and Z syndromes jointly + to identify Y errors and improve accuracy. + + Args: + synx_list: List of X syndrome arrays, one per round + synz_list: List of Z syndrome arrays, one per round + final: Final data qubit measurements + + Returns: + (is_logical_error, decoding_result) + """ + import numpy as np + + geom = self.patch.geometry + logical_z_qubits = geom.logical_z.data_qubits if geom.logical_z else () + final_parity = sum(final[q] for q in logical_z_qubits) % 2 + + # Compute detection events for both bases. + x_events = self._compute_dem_detection_events_x(synx_list, synz_list, final) + z_events = self._compute_dem_detection_events_z(synx_list, synz_list, final) + x_flat = x_events.ravel().astype(np.uint8) + z_flat = z_events.ravel().astype(np.uint8) + + # Joint decode via UIUF. + decoder = self._get_css_uf_decoder() + x_obs, z_obs = decoder.decode_css(bytes(x_flat), bytes(z_flat)) + + # For Z-basis memory, we care about the Z observable (L0). + predicted_obs = z_obs & 1 + corrected_parity = (final_parity + predicted_obs) % 2 + is_logical_error = corrected_parity != 0 + + return is_logical_error, DecodingResult( + x_correction=np.zeros(self.patch.num_data, dtype=np.uint8), + z_correction=np.zeros(self.patch.num_data, dtype=np.uint8), + logical_x_flip=bool(x_obs & 1), + logical_z_flip=bool(predicted_obs), + decoding_weight=0.0, + ) + @dataclass class SimulationResult: @@ -1603,7 +2389,7 @@ def run_noisy_memory_experiment( Example: >>> from pecos.qec.surface import run_noisy_memory_experiment, NoiseModel - >>> noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.01, p_init=0.001) + >>> noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.01, p_prep=0.001) >>> result = run_noisy_memory_experiment( ... distance=3, ... num_rounds=3, @@ -1633,11 +2419,13 @@ def run_noisy_memory_experiment( # Create decoder if needed decoder = None if decode: + # UIUF uses pymatching-type DEMs internally (decoded via CssUfDecoder). + dt = "pymatching" if decoder_type == "pecos_uf_uiuf" else decoder_type decoder = SurfaceDecoder( patch, num_rounds=num_rounds, noise=noise, - decoder_type=decoder_type, + decoder_type=dt, ) # Build and compile circuit @@ -1651,7 +2439,7 @@ def run_noisy_memory_experiment( p_1q=noise.p1, p_2q=noise.p2, p_meas=noise.p_meas, - p_init=noise.p_init, + p_init=noise.p_prep, ) # Run shots @@ -1692,7 +2480,9 @@ def run_noisy_memory_experiment( final_arr = np.array(final, dtype=np.uint8) # Decode based on basis - if basis.upper() == "Z": + if decoder_type == "pecos_uf_uiuf" and basis.upper() == "Z": + is_error, _ = decoder.decode_memory_z_uiuf(synx_list, synz_list, final_arr) + elif basis.upper() == "Z": is_error, _ = decoder.decode_memory_z(synx_list, synz_list, final_arr) else: is_error, _ = decoder.decode_memory_x(synx_list, synz_list, final_arr) @@ -1727,30 +2517,32 @@ def run_noisy_memory_experiment( class NativeSampler: """PECOS native sampler for threshold estimation. - This provides a pure-PECOS alternative to Stim's DEM sampler, - using the MeasurementNoiseModel (MNM) for efficient sampling. + This provides a pure-PECOS alternative to Stim's DEM sampler. The sampler uses explicit detector and observable definitions from - TickCircuit metadata, matching Stim's output format closely (~98% - per-detector correlation in testing). + TickCircuit metadata, matching Stim's output format closely. Two sampling backends are available: - - MNM (default): Samples measurement outcomes, computes events from definitions - - NoisySampler: Samples fault locations directly (faster for statistics) + - `dem` (default): sample the generated decomposed DEM via `ParsedDem` + - `influence_dem`: sample directly from the influence-map via `DemSampler` Attributes: - mnm: The MeasurementNoiseModel for sampling + sampler: The underlying Rust sampler object detectors_json: JSON string with detector definitions observables_json: JSON string with observable definitions num_detectors: Number of detectors num_observables: Number of observables + sampling_model: Which native sampling backend is active """ - mnm: MeasurementNoiseModel + sampler: Any detectors_json: str observables_json: str num_detectors: int num_observables: int + sampling_model: Literal["dem", "influence_dem", "mnm"] = ( + "dem" # "mnm" accepted for compat, mapped to "influence_dem" + ) def sample( self, @@ -1770,12 +2562,7 @@ def sample( - detection_events: shape (num_shots, num_detectors) - observable_flips: shape (num_shots, num_observables) """ - det_events, obs_flips = self.mnm.sample_batch_for_decoding( - num_shots, - self.detectors_json, - self.observables_json, - seed, - ) + det_events, obs_flips = self.sampler.sample_batch(num_shots, seed) return np.array(det_events, dtype=bool), np.array(obs_flips, dtype=bool) @@ -1784,6 +2571,13 @@ def build_native_sampler( num_rounds: int, noise: NoiseModel, basis: str = "Z", + ancilla_budget: int | None = None, + circuit_source: Literal["abstract", "traced_qis"] = "abstract", + sampling_model: Literal[ + "dem", + "influence_dem", + "mnm", + ] = "dem", # "mnm" accepted for compat, mapped to "influence_dem", ) -> NativeSampler: """Build a PECOS native sampler for threshold estimation. @@ -1792,13 +2586,27 @@ def build_native_sampler( Stim's DEM sampler. The pipeline is: - TickCircuit -> DagCircuit -> DagFaultAnalyzer -> InfluenceMap -> MNM -> Sampler + - `sampling_model="dem"`: + TickCircuit -> DemBuilder -> ParsedDem -> DemSampler + - `sampling_model="influence_dem"` (or `"mnm"` for compat): + TickCircuit -> DagCircuit -> DagFaultAnalyzer -> InfluenceMap -> DemSampler (with detector defs) Args: patch: Surface code patch with geometry num_rounds: Number of syndrome extraction rounds noise: Noise model parameters basis: Memory basis ('X' or 'Z') + ancilla_budget: Optional cap on simultaneously live ancillas + circuit_source: Which ideal circuit to analyze for the native sampler + path. ``"abstract"`` uses the existing high-level surface + TickCircuit. ``"traced_qis"`` traces the lowered ideal Selene/QIS + gate stream and replays that exact gate list into a TickCircuit + before native PECOS fault analysis. + sampling_model: Which native sampling backend to use. ``"dem"`` + samples the generated decomposed DEM and is the default. + ``"influence_dem"`` uses the influence-map-based DemSampler with + detector definitions. ``"mnm"`` is accepted for compatibility + and maps to ``"influence_dem"``. Returns: NativeSampler that can generate samples for threshold estimation @@ -1810,41 +2618,56 @@ def build_native_sampler( >>> sampler = build_native_sampler(patch, num_rounds=5, noise=noise) >>> detection_events, observable_flips = sampler.sample(num_shots=10000) """ - import json + if _can_use_cached_surface_topology(ancilla_budget=ancilla_budget): + basis = basis.upper() + patch_key = _surface_patch_cache_key(patch) + topology = _cached_surface_native_topology( + patch_key, + num_rounds, + basis, + ancilla_budget, + circuit_source, + ) + if sampling_model == "dem": + dem_str = _cached_surface_native_dem_string( + patch_key, + num_rounds, + basis, + ancilla_budget, + circuit_source, + noise.p1, + noise.p2, + noise.p_meas, + noise.p_prep, + decompose_errors=True, + p_idle=noise.p_idle, + t1=noise.t1, + t2=noise.t2, + ) + sampler = _cached_parsed_dem(dem_str).to_dem_sampler() + return NativeSampler( + sampler=sampler, + detectors_json=topology.detectors_json, + observables_json=topology.observables_json, + num_detectors=topology.num_detectors, + num_observables=topology.num_observables, + sampling_model=sampling_model, + ) + return _build_native_sampler_from_cached_surface_topology( + topology, + noise, + sampling_model=sampling_model, + ) - from pecos.qec import DagFaultAnalyzer, MemBuilder - from pecos.qec.surface.circuit_builder import ( - _extract_measurement_order, - generate_tick_circuit_from_patch, + tc = _build_surface_tick_circuit_for_native_model( + patch, + num_rounds, + basis, + ancilla_budget=ancilla_budget, + circuit_source=circuit_source, ) - - # Generate TickCircuit (source of truth for circuit structure) - tc = generate_tick_circuit_from_patch(patch, num_rounds, basis) - - # Convert to DAG and build influence map via Rust fault propagation - dag = tc.to_dag_circuit() - analyzer = DagFaultAnalyzer(dag) - influence_map = analyzer.build_influence_map() - - # Extract metadata from TickCircuit - detectors_json = tc.get_meta("detectors") or "[]" - observables_json = tc.get_meta("observables") or "[]" - measurement_order = _extract_measurement_order(tc) - - # Build MNM for sampling - builder = MemBuilder(influence_map) - builder.with_noise(noise.p1, noise.p2, noise.p_meas, noise.p_init) - builder.with_measurement_order(measurement_order) - mnm = builder.build() - - # Parse to count detectors/observables - num_detectors = len(json.loads(detectors_json)) if detectors_json else 0 - num_observables = len(json.loads(observables_json)) if observables_json else 0 - - return NativeSampler( - mnm=mnm, - detectors_json=detectors_json, - observables_json=observables_json, - num_detectors=num_detectors, - num_observables=num_observables, + return _build_native_sampler_from_tick_circuit( + tc, + noise, + sampling_model=sampling_model, ) diff --git a/python/quantum-pecos/src/pecos/qec/surface/layouts/rotated_lattice.py b/python/quantum-pecos/src/pecos/qec/surface/layouts/rotated_lattice.py index 1d92b947c..e62938f88 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/layouts/rotated_lattice.py +++ b/python/quantum-pecos/src/pecos/qec/surface/layouts/rotated_lattice.py @@ -32,22 +32,28 @@ class RotatedPosition: y: int -def compute_rotated_x_stabilizers(d: int) -> list[StabilizerSupport]: +def compute_rotated_x_stabilizers(dx: int, dz: int | None = None) -> list[StabilizerSupport]: """Compute X stabilizer supports for rotated surface code. X stabilizers are placed at dual lattice faces where (row + col) is odd. Boundary X stabilizers (weight 2) are on the top and bottom edges. - This convention matches the QASM reference and Rust implementations. + Degenerate cases: + - dx=1: no X stabilizers (single row, no top/bottom boundary) + - dz=1: no X stabilizers (single column, no X-type faces) + - dx=1, dz=1: single qubit, no stabilizers Args: - d: Code distance (must be odd >= 3) + dx: Number of rows (X distance). Must be >= 1. + dz: Number of columns (Z distance). Must be >= 1. Defaults to dx. Returns: List of StabilizerSupport for X stabilizers """ - if d < 3 or d % 2 == 0: - msg = f"Distance must be odd >= 3, got {d}" + if dz is None: + dz = dx + if dx < 1 or dz < 1: + msg = f"Distances must be >= 1, got dx={dx}, dz={dz}" raise ValueError(msg) supports = [] @@ -55,7 +61,7 @@ def compute_rotated_x_stabilizers(d: int) -> list[StabilizerSupport]: # Top boundary X stabilizers (weight 2) # Virtual dual row r=-1: X-type when (-1+col)%2==1, i.e. col even - for col in range(0, d - 1, 2): + for col in range(0, dz - 1, 2): q1 = col q2 = col + 1 supports.append( @@ -68,13 +74,13 @@ def compute_rotated_x_stabilizers(d: int) -> list[StabilizerSupport]: stab_idx += 1 # Bulk X stabilizers (weight 4) - for row in range(d - 1): - for col in range(d - 1): + for row in range(dx - 1): + for col in range(dz - 1): if (row + col) % 2 == 1: - q_tl = row * d + col - q_tr = row * d + col + 1 - q_bl = (row + 1) * d + col - q_br = (row + 1) * d + col + 1 + q_tl = row * dz + col + q_tr = row * dz + col + 1 + q_bl = (row + 1) * dz + col + q_br = (row + 1) * dz + col + 1 supports.append( StabilizerSupport( @@ -86,10 +92,11 @@ def compute_rotated_x_stabilizers(d: int) -> list[StabilizerSupport]: stab_idx += 1 # Bottom boundary X stabilizers (weight 2) - # Virtual dual row r=d-1: for odd d, (d-1+col)%2==1 requires col odd - for col in range(1, d - 1, 2): - q1 = (d - 1) * d + col - q2 = (d - 1) * d + col + 1 + # Virtual dual row r=dx-1: X-type when (dx-1+col)%2==1 + bottom_start = 1 if dx % 2 == 1 else 0 + for col in range(bottom_start, dz - 1, 2): + q1 = (dx - 1) * dz + col + q2 = (dx - 1) * dz + col + 1 supports.append( StabilizerSupport( index=stab_idx, @@ -102,32 +109,39 @@ def compute_rotated_x_stabilizers(d: int) -> list[StabilizerSupport]: return supports -def compute_rotated_z_stabilizers(d: int) -> list[StabilizerSupport]: +def compute_rotated_z_stabilizers(dx: int, dz: int | None = None) -> list[StabilizerSupport]: """Compute Z stabilizer supports for rotated surface code. Z stabilizers are placed at dual lattice faces where (row + col) is even. Boundary Z stabilizers (weight 2) are on the left and right edges. - This convention matches the QASM reference and Rust implementations. + Degenerate cases: + - dz=1: no Z stabilizers (single column, no left/right boundary) + - dx=1: Z stabilizers become the repetition code parity checks + - dx=1, dz=1: single qubit, no stabilizers Args: - d: Code distance (must be odd >= 3) + dx: Number of rows (X distance). Must be >= 1. + dz: Number of columns (Z distance). Must be >= 1. Defaults to dx. Returns: List of StabilizerSupport for Z stabilizers """ - if d < 3 or d % 2 == 0: - msg = f"Distance must be odd >= 3, got {d}" + if dz is None: + dz = dx + if dx < 1 or dz < 1: + msg = f"Distances must be >= 1, got dx={dx}, dz={dz}" raise ValueError(msg) supports = [] stab_idx = 0 # Right boundary Z stabilizers (weight 2) - # Virtual dual col c=d-1: Z-type when (row+d-1)%2==0, i.e. row even (for odd d) - for row in range(0, d - 1, 2): - q1 = row * d + (d - 1) - q2 = (row + 1) * d + (d - 1) + # Virtual dual col c=dz-1: Z-type when (row+dz-1)%2==0 + right_start = 0 if dz % 2 == 1 else 1 + for row in range(right_start, dx - 1, 2): + q1 = row * dz + (dz - 1) + q2 = (row + 1) * dz + (dz - 1) supports.append( StabilizerSupport( index=stab_idx, @@ -138,13 +152,13 @@ def compute_rotated_z_stabilizers(d: int) -> list[StabilizerSupport]: stab_idx += 1 # Bulk Z stabilizers (weight 4) - for row in range(d - 1): - for col in range(d - 1): + for row in range(dx - 1): + for col in range(dz - 1): if (row + col) % 2 == 0: - q_tl = row * d + col - q_tr = row * d + col + 1 - q_bl = (row + 1) * d + col - q_br = (row + 1) * d + col + 1 + q_tl = row * dz + col + q_tr = row * dz + col + 1 + q_bl = (row + 1) * dz + col + q_br = (row + 1) * dz + col + 1 supports.append( StabilizerSupport( @@ -156,10 +170,10 @@ def compute_rotated_z_stabilizers(d: int) -> list[StabilizerSupport]: stab_idx += 1 # Left boundary Z stabilizers (weight 2) - # Virtual dual col c=-1: Z-type when (row+(-1))%2==0, i.e. row odd - for row in range(1, d - 1, 2): - q1 = row * d - q2 = (row + 1) * d + # Virtual dual col c=-1: Z-type when (row-1)%2==0, i.e. row odd + for row in range(1, dx - 1, 2): + q1 = row * dz + q2 = (row + 1) * dz supports.append( StabilizerSupport( index=stab_idx, @@ -172,8 +186,8 @@ def compute_rotated_z_stabilizers(d: int) -> list[StabilizerSupport]: # Re-order: left-to-right (ascending column), bottom-to-top (descending row) supports.sort( key=lambda s: ( - sum(q % d for q in s.data_qubits) / len(s.data_qubits), - -sum(q // d for q in s.data_qubits) / len(s.data_qubits), + sum(q % dz for q in s.data_qubits) / len(s.data_qubits), + -sum(q // dz for q in s.data_qubits) / len(s.data_qubits), ), ) return [ @@ -181,14 +195,18 @@ def compute_rotated_z_stabilizers(d: int) -> list[StabilizerSupport]: ] -def get_rotated_logical_x(d: int) -> tuple[int, ...]: - """Get logical X operator qubits (left edge).""" - return tuple(i * d for i in range(d)) +def get_rotated_logical_x(dx: int, dz: int | None = None) -> tuple[int, ...]: + """Get logical X operator qubits (left edge, weight dx).""" + if dz is None: + dz = dx + return tuple(i * dz for i in range(dx)) -def get_rotated_logical_z(d: int) -> tuple[int, ...]: - """Get logical Z operator qubits (top edge).""" - return tuple(range(d)) +def get_rotated_logical_z(dx: int, dz: int | None = None) -> tuple[int, ...]: + """Get logical Z operator qubits (top edge, weight dz).""" + if dz is None: + dz = dx + return tuple(range(dz)) def rotated_id_to_position(qubit_id: int, d: int) -> tuple[int, int]: diff --git a/python/quantum-pecos/src/pecos/qec/surface/logical_circuit.py b/python/quantum-pecos/src/pecos/qec/surface/logical_circuit.py new file mode 100644 index 000000000..25afd073d --- /dev/null +++ b/python/quantum-pecos/src/pecos/qec/surface/logical_circuit.py @@ -0,0 +1,1590 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Logical circuit builder for surface codes with transversal gates. + +Generates PECOS TickCircuit circuits natively, with Stim circuit strings +derived via ``tick_circuit_to_stim()``. Supports: + +- Memory experiments (syndrome extraction rounds) +- Transversal Hadamard (H on all data qubits, swaps X<->Z stabilizers) +- Transversal CNOT (CX between corresponding data qubits of two patches) +- Transversal SZ via gate teleportation (CX + |+Y> ancilla consumption) + +Output formats: + +- ``to_tick_circuit()`` -- PECOS TickCircuit (source of truth) +- ``to_dag_circuit()`` -- PECOS DagCircuit (for fault analysis) +- ``to_stim()`` -- Stim circuit string (derived from TickCircuit) +- ``build_dem()`` -- DEM via PECOS DagFaultAnalyzer (no Stim) +- ``build_decoder()`` -- integrated decoder pipeline + +References: +- Geher et al., "Error-corrected Hadamard gate" (arXiv:2312.11605) +- Sahay et al., "Error correction of transversal CNOT" (arXiv:2408.01393) +- Serra-Peralta et al., "Decoding across transversal Clifford gates" (arXiv:2505.13599) +""" + +from __future__ import annotations + +from dataclasses import dataclass, field +from enum import Enum, auto +from typing import TYPE_CHECKING + +if TYPE_CHECKING: + from pecos.qec.surface.patch import SurfacePatch + + +class LogicalGateType(Enum): + """Types of logical operations in a surface code circuit.""" + + MEMORY = auto() + TRANSVERSAL_H = auto() + TRANSVERSAL_SZ = auto() + TRANSVERSAL_SZdg = auto() + TRANSVERSAL_CX = auto() + + +@dataclass +class PatchState: + """Tracks the stabilizer assignment state of a patch. + + After transversal H, X-stabilizers become Z-stabilizers and vice versa. + This state tracks which physical stabilizers are currently X-type vs Z-type, + so that detectors can be formed correctly across gate boundaries. + """ + + patch: SurfacePatch + label: str + qubit_offset: int = 0 + coord_offset: tuple[float, float] = (0.0, 0.0) + x_z_swapped: bool = False + # Teleportation corrections: ancilla Z measurements to XOR into this + # patch's observable (from CX teleportation gates). + z_obs_includes: list[str] = field(default_factory=list) + x_obs_includes: list[str] = field(default_factory=list) + # After CX, some observables become non-reliable depending on the + # measurement basis. Track which bases are "entangled" and with whom. + # x_entangled_with: this patch's X observable is entangled with these + # patches (measuring X on this patch alone is non-deterministic). + x_entangled_with: list[str] = field(default_factory=list) + z_entangled_with: list[str] = field(default_factory=list) + + @property + def current_x_stabilizers(self): + """Stabilizers currently measuring X-type checks.""" + if self.x_z_swapped: + return self.patch.geometry.z_stabilizers + return self.patch.geometry.x_stabilizers + + @property + def current_z_stabilizers(self): + """Stabilizers currently measuring Z-type checks.""" + if self.x_z_swapped: + return self.patch.geometry.x_stabilizers + return self.patch.geometry.z_stabilizers + + +@dataclass +class LogicalOp: + """A logical operation in the circuit.""" + + gate_type: LogicalGateType + patches: list[str] + rounds: int = 0 + basis: str = "Z" + per_patch_basis: dict[str, str] = field(default_factory=dict) + # For teleportation CX: the target's Z measurement should be included + # in the control's observable for the Pauli frame correction. + teleportation: bool = False + # Type of magic state injection: "T" for T-gate, "SZ" for SZ, or None. + # Used by build_algorithm_descriptor() to emit the correct boundary gate. + injection_type: str | None = None + + +class LogicalCircuitBuilder: + """Builds surface code circuits with transversal gates. + + Composes logical operations on one or more patches, generating Stim + circuits with correct detector annotations across gate boundaries. + + Example:: + + patch = SurfacePatch.create(distance=3) + builder = LogicalCircuitBuilder() + builder.add_patch(patch, "A") + builder.add_memory("A", rounds=3, basis="Z") + builder.add_transversal_h("A") + builder.add_memory("A", rounds=3, basis="X") + stim_str = builder.to_stim(p1=0.001, p2=0.001) + """ + + def __init__(self) -> None: + self._patches: dict[str, PatchState] = {} + self._operations: list[LogicalOp] = [] + + def add_patch( + self, + patch: SurfacePatch, + label: str, + qubit_offset: int = 0, + coord_offset: tuple[float, float] | None = None, + ) -> None: + """Register a surface code patch. + + Args: + patch: The surface code patch. + label: Unique label for this patch. + qubit_offset: Offset added to all qubit indices for this patch. + Use this when multiple patches share a qubit index space. + coord_offset: (dx, dy) spatial offset for this patch's + QUBIT_COORDS and DETECTOR coordinates. If None, computed + automatically based on patch index (patches are spaced + apart so coordinates don't overlap). + """ + if label in self._patches: + msg = f"Patch '{label}' already registered" + raise ValueError(msg) + if coord_offset is None: + # Auto-space: shift each patch by (d*2 + 2) * patch_index in x + patch_idx = len(self._patches) + spacing = patch.geometry.dz * 2 + 2 + coord_offset = (patch_idx * spacing, 0.0) + self._patches[label] = PatchState( + patch=patch, + label=label, + qubit_offset=qubit_offset, + coord_offset=coord_offset, + ) + + def add_memory( + self, + patch_labels: str | list[str], + rounds: int, + basis: str | dict[str, str] = "Z", + ) -> None: + """Add syndrome extraction rounds for one or more patches. + + When multiple patches are given, their syndrome extraction runs + in parallel (same time window). + + Args: + patch_labels: Label(s) of the patch(es). String for single + patch, list for parallel multi-patch. + rounds: Number of syndrome extraction rounds. + basis: Measurement basis. Either a single string ('X', 'Y', 'Z') + applied to all patches, or a dict mapping patch labels to + their individual basis (e.g., ``{"D": "Z", "Y": "Y"}``). + Only used for initialization and final measurement. + """ + if isinstance(patch_labels, str): + patch_labels = [patch_labels] + for label in patch_labels: + if label not in self._patches: + msg = f"Unknown patch '{label}'" + raise ValueError(msg) + + if isinstance(basis, str): + default_basis = basis.upper() + per_patch = {} + else: + default_basis = "Z" + per_patch = {k: v.upper() for k, v in basis.items()} + + self._operations.append( + LogicalOp( + gate_type=LogicalGateType.MEMORY, + patches=list(patch_labels), + rounds=rounds, + basis=default_basis, + per_patch_basis=per_patch, + ) + ) + + def _require_square(self, patch_label: str, gate_name: str) -> None: + """Check that a patch is square (dx=dz), required for transversal gates.""" + patch = self._patches[patch_label].patch + if patch.geometry.dx != patch.geometry.dz: + msg = ( + f"{gate_name} requires a square patch (dx=dz), " + f"got dx={patch.geometry.dx}, dz={patch.geometry.dz}" + ) + raise ValueError(msg) + + def add_transversal_h(self, patch_label: str) -> None: + """Add a transversal Hadamard gate on a patch. + + Applies H to every data qubit. After this: + - X-stabilizers become Z-stabilizers and vice versa + - Logical X and logical Z are exchanged + - Detectors at the boundary compare cross-type measurements + + The patch must be square (dx=dz) for the code to remain valid. + + Args: + patch_label: Label of the patch. + """ + if patch_label not in self._patches: + msg = f"Unknown patch '{patch_label}'" + raise ValueError(msg) + self._require_square(patch_label, "Transversal H") + self._operations.append( + LogicalOp( + gate_type=LogicalGateType.TRANSVERSAL_H, + patches=[patch_label], + ) + ) + + def add_transversal_sz(self, patch_label: str) -> None: + """Add a fold-transversal SZ gate on a patch. + + Implements the fold-transversal S gate using the Bravyi et al. + half-cycle trick (arXiv:2412.01391). The fold operation is + inserted at mid-cycle of a syndrome extraction round: + - On-diagonal data qubits (r + c = d-1): SZ gate + - On-diagonal X-ancilla qubits: SZdg gate + - Off-diagonal: CZ between each qubit and its mirror + + After this gate: + - Z-stabilizers are unchanged + - X-stabilizers pick up Z-stabilizer partners: + X_stab -> X_stab * Z_stab_mirror + + The patch must be square (dx=dz). + + Args: + patch_label: Label of the patch. + """ + if patch_label not in self._patches: + msg = f"Unknown patch '{patch_label}'" + raise ValueError(msg) + self._require_square(patch_label, "Transversal SZ") + self._operations.append( + LogicalOp( + gate_type=LogicalGateType.TRANSVERSAL_SZ, + patches=[patch_label], + ) + ) + + def add_transversal_szdg(self, patch_label: str) -> None: + """Add SZdg (S-dagger) on all data qubits of a patch. + + Inverse of add_transversal_sz. Used for mirroring circuits + that contain SZ gates. + """ + if patch_label not in self._patches: + msg = f"Unknown patch '{patch_label}'" + raise ValueError(msg) + self._require_square(patch_label, "Transversal SZdg") + self._operations.append( + LogicalOp( + gate_type=LogicalGateType.TRANSVERSAL_SZdg, + patches=[patch_label], + ) + ) + + def add_sz_via_teleportation( + self, + data_label: str, + ancilla_label: str, + rounds_before: int = 3, + rounds_after: int = 3, + ) -> None: + """Apply logical SZ via gate teleportation with |+Y> ancilla. + + Complete protocol: + 1. Prepare ancilla in |+Y> = S|+> (non-fault-tolerant injection) + 2. Syndrome rounds to project ancilla into code space + 3. Transversal CX(data=control, ancilla=target) + 4. Syndrome rounds + 5. Ancilla measured in Z-basis (final round) + + After CX, data has S|psi> (up to Z correction from ancilla outcome). + The Z correction is a Pauli frame update tracked by the decoder. + + Note: The |+Y> injection is non-fault-tolerant (distance-1). + For fault-tolerant SZ, use magic state distillation on the + injected state before consumption. + + Args: + data_label: Label of the data patch (receives the SZ gate). + ancilla_label: Label of the ancilla patch (consumed). + rounds_before: Syndrome rounds before CX. + rounds_after: Syndrome rounds after CX. + """ + # Step 1: Init both patches — data continues in Z, ancilla in |+Y>. + # Per-patch basis lets us do this in a single parallel segment. + self.add_memory( + [data_label, ancilla_label], + rounds=rounds_before, + basis={data_label: "Z", ancilla_label: "Y"}, + ) + # Step 2: CX(data=control, ancilla=target) — teleports S onto data. + # Marked as teleportation so observable propagation includes the + # ancilla's Z measurement as a Pauli frame correction. + self._operations.append( + LogicalOp( + gate_type=LogicalGateType.TRANSVERSAL_CX, + patches=[data_label, ancilla_label], + teleportation=True, + ) + ) + # Step 3: Post-CX extraction. Ancilla measured in Z-basis at final round. + # If ancilla measures logical -1, apply Z correction (Pauli frame update). + self.add_memory([data_label, ancilla_label], rounds=rounds_after, basis="Z") + + def add_t_via_injection( + self, + data_label: str, + ancilla_label: str, + rounds_before: int = 3, + rounds_after: int = 3, + ) -> None: + """Apply logical T gate via magic state injection. + + Complete protocol: + 1. Prepare ancilla in |T> = T|+> (non-fault-tolerant injection) + 2. Syndrome rounds to project ancilla into code space + 3. Transversal CX(data=control, ancilla=target) + 4. Syndrome rounds + 5. Ancilla measured in Z-basis (final round) + + After CX, data has T|psi> (up to S correction from ancilla outcome). + The S correction is a conditional feed-forward operation — this is + a DECISION POINT where the decoder must provide the Pauli frame. + + The corrected measurement outcome determines: + corrected = raw_measurement XOR frame[z_obs_bit] + if corrected == 1: apply S gate on data + + Note: The |T> injection is non-fault-tolerant (distance-1). + For fault-tolerant T, use magic state distillation on the + injected state before consumption. + + Args: + data_label: Label of the data patch (receives the T gate). + ancilla_label: Label of the ancilla patch (consumed). + rounds_before: Syndrome rounds before CX. + rounds_after: Syndrome rounds after CX. + """ + # Step 1: Init both patches — data continues in Z, ancilla gets |+>. + # The real protocol prepares |T> = T|+> on the ancilla, but T is + # non-Clifford and invisible to the fault analyzer. We prepare + # |+> as a Clifford stand-in: same error structure (H gate noise + # via p1, prep noise via p_prep), just missing the non-Clifford + # phase which doesn't affect error correlations in the DEM. + self.add_memory( + [data_label, ancilla_label], + rounds=rounds_before, + basis={data_label: "Z", ancilla_label: "X"}, + ) + # Step 2: CX(data=control, ancilla=target) — teleports T onto data. + self._operations.append( + LogicalOp( + gate_type=LogicalGateType.TRANSVERSAL_CX, + patches=[data_label, ancilla_label], + teleportation=True, + injection_type="T", + ) + ) + # Step 3: Post-CX extraction. Ancilla measured in Z-basis. + # If ancilla measures logical -1 (corrected by frame), apply S. + # This is the feed-forward decision point. + self.add_memory( + [data_label, ancilla_label], + rounds=rounds_after, + basis="Z", + ) + + def add_transversal_cx(self, control_label: str, target_label: str) -> None: + """Add a transversal CNOT between two patches. + + Applies CX between corresponding data qubits. After this: + - X-errors on control propagate to target + - Z-errors on target propagate back to control + - Weight-3 hyperedges appear in the DEM at the gate boundary + + Both patches must have the same geometry. + + Args: + control_label: Label of the control patch. + target_label: Label of the target patch. + """ + if control_label not in self._patches: + msg = f"Unknown patch '{control_label}'" + raise ValueError(msg) + if target_label not in self._patches: + msg = f"Unknown patch '{target_label}'" + raise ValueError(msg) + ctrl = self._patches[control_label] + tgt = self._patches[target_label] + if ctrl.patch.geometry.num_data != tgt.patch.geometry.num_data: + msg = ( + f"Patches must have same geometry for transversal CX. " + f"'{control_label}' has {ctrl.patch.geometry.num_data} data qubits, " + f"'{target_label}' has {tgt.patch.geometry.num_data} data qubits." + ) + raise ValueError(msg) + self._operations.append( + LogicalOp( + gate_type=LogicalGateType.TRANSVERSAL_CX, + patches=[control_label, target_label], + ) + ) + + def _snapshot_and_reset(self): + """Snapshot patch states and reset for generation.""" + saved = { + label: ( + ps.x_z_swapped, + list(ps.z_obs_includes), + list(ps.x_obs_includes), + list(ps.x_entangled_with), + list(ps.z_entangled_with), + ) + for label, ps in self._patches.items() + } + for ps in self._patches.values(): + ps.x_z_swapped = False + ps.z_obs_includes = [] + ps.x_obs_includes = [] + ps.x_entangled_with = [] + ps.z_entangled_with = [] + return saved + + def _restore(self, saved): + """Restore patch states from snapshot.""" + for label, (swapped, z_obs, x_obs, x_ent, z_ent) in saved.items(): + ps = self._patches[label] + ps.x_z_swapped = swapped + ps.z_obs_includes = z_obs + ps.x_obs_includes = x_obs + ps.x_entangled_with = x_ent + ps.z_entangled_with = z_ent + + def to_tick_circuit(self): + """Generate a PECOS TickCircuit with detector and observable annotations. + + This is the primary output — the TickCircuit is the source of truth. + Use ``to_stim()`` for Stim format (derived from TickCircuit via + ``tick_circuit_to_stim``), or ``.to_dag_circuit()`` for fault analysis. + + Returns: + TickCircuit with gates, detectors, and observables as metadata. + """ + saved = self._snapshot_and_reset() + gen = _CircuitGenerator( + patches=self._patches, + operations=self._operations, + ) + tc = gen.generate() + self._restore(saved) + return tc + + def to_dag_circuit(self): + """Generate a PECOS DagCircuit for fault analysis. + + Converts the TickCircuit to a DagCircuit, which can be used + with ``DagFaultAnalyzer`` for fault propagation analysis. + + Returns: + DagCircuit instance. + """ + return self.to_tick_circuit().to_dag_circuit() + + def to_stim( + self, + *, + p1: float = 0.0, + p2: float = 0.0, + p_meas: float = 0.0, + p_prep: float = 0.0, + ) -> str: + """Generate a Stim circuit string with correct detectors. + + Builds a TickCircuit (source of truth), then converts to Stim + format with noise injection via ``tick_circuit_to_stim()``. + + Args: + p1: Single-qubit depolarizing error rate. + p2: Two-qubit depolarizing error rate. + p_meas: Measurement error rate. + p_prep: Preparation error rate. + + Returns: + Stim circuit string. + """ + from pecos.qec.surface.circuit_builder import tick_circuit_to_stim + + tc = self.to_tick_circuit() + return tick_circuit_to_stim(tc, p1=p1, p2=p2, p_meas=p_meas, p_prep=p_prep) + + def stab_coords(self) -> list[dict[str, list[tuple[float, float]]]]: + """Compute stabilizer coordinates for all patches. + + Returns a list (one per patch, in registration order) of dicts + with keys "X" and "Z" mapping to ancilla (x, y) positions. + These coordinates match the detector annotations in the Stim circuit. + + Used as input to ``ObservableSubgraphDecoder``. + """ + result = [] + for ps in self._patches.values(): + geom = ps.patch.geometry + cx, cy = ps.coord_offset + x_coords = [] + for s in geom.x_stabilizers: + positions = [geom.id_to_pos[q] for q in s.data_qubits] + avg_row = sum(r for r, c in positions) / len(positions) + avg_col = sum(c for r, c in positions) / len(positions) + x_coords.append((avg_col * 2 + cx, avg_row * 2 + cy)) + z_coords = [] + for s in geom.z_stabilizers: + positions = [geom.id_to_pos[q] for q in s.data_qubits] + avg_row = sum(r for r, c in positions) / len(positions) + avg_col = sum(c for r, c in positions) / len(positions) + z_coords.append((avg_col * 2 + cx, avg_row * 2 + cy)) + result.append({"X": x_coords, "Z": z_coords}) + return result + + def build_dem( + self, + *, + p1: float = 0.001, + p2: float = 0.001, + p_meas: float = 0.001, + p_prep: float = 0.0, + ) -> str: + """Generate a DEM using the PECOS-native fault analysis pipeline. + + TickCircuit -> DagCircuit -> DagFaultAnalyzer -> DemBuilder. + No Stim dependency. + + Args: + p1: Single-qubit depolarizing error rate. + p2: Two-qubit depolarizing error rate. + p_meas: Measurement error rate. + p_prep: Preparation error rate. + + Returns: + DEM string in Stim-compatible format. + """ + from pecos_rslib.qec import DagFaultAnalyzer, DemBuilder + + tc = self.to_tick_circuit() + dc = tc.to_dag_circuit() + analyzer = DagFaultAnalyzer(dc) + influence_map = analyzer.build_influence_map() + + det_json = tc.get_meta("detectors") + obs_json = tc.get_meta("observables") + num_meas = int(tc.get_meta("num_measurements")) + + meas_order = [] + for tick_idx in range(tc.num_ticks()): + tick = tc.get_tick(tick_idx) + for gate in tick.gates(): + if gate.gate_type.name == "MZ": + for q in gate.qubits: + meas_order.append(int(q)) + + dem_builder = DemBuilder(influence_map) + dem_builder = dem_builder.with_noise(p1, p2, p_meas, p_prep) + dem_builder = dem_builder.with_detectors_json(det_json) + dem_builder = dem_builder.with_observables_json(obs_json) + dem_builder = dem_builder.with_num_measurements(num_meas) + dem_builder = dem_builder.with_measurement_order(meas_order) + + return str(dem_builder.build()) + + def build_sampler_and_decoder( + self, + *, + p1: float = 0.001, + p2: float = 0.001, + p_meas: float = 0.001, + p_prep: float = 0.0, + inner_decoder: str = "pymatching", + ): + """Build a DemSampler and OSD decoder without any string round-trip. + + Returns: + Tuple of (DemSampler, ObservableSubgraphDecoder, dem_str). + dem_str is also returned for compatibility with existing code. + """ + from pecos_rslib.qec import DagFaultAnalyzer, DemBuilder, ObservableSubgraphDecoder + + tc = self.to_tick_circuit() + dc = tc.to_dag_circuit() + analyzer = DagFaultAnalyzer(dc) + influence_map = analyzer.build_influence_map() + + det_json = tc.get_meta("detectors") + obs_json = tc.get_meta("observables") + num_meas = int(tc.get_meta("num_measurements")) + + meas_order = [] + for tick_idx in range(tc.num_ticks()): + tick = tc.get_tick(tick_idx) + for gate in tick.gates(): + if gate.gate_type.name == "MZ": + for q in gate.qubits: + meas_order.append(int(q)) + + dem_builder = DemBuilder(influence_map) + dem_builder = dem_builder.with_noise(p1, p2, p_meas, p_prep) + dem_builder = dem_builder.with_detectors_json(det_json) + dem_builder = dem_builder.with_observables_json(obs_json) + dem_builder = dem_builder.with_num_measurements(num_meas) + dem_builder = dem_builder.with_measurement_order(meas_order) + + dem = dem_builder.build() + sampler = dem.to_sampler() + dem_str = str(dem) + + sc = self.stab_coords() + decoder = ObservableSubgraphDecoder(dem_str, sc, inner_decoder) + + return sampler, decoder, dem_str + + def build_algorithm_descriptor( + self, + *, + p1: float = 0.001, + p2: float = 0.001, + p_meas: float = 0.001, + p_prep: float = 0.0, + buffer: int = 0, + ) -> dict: + """Extract per-segment DEMs and boundary gates for LogicalAlgorithmDecoder. + + Splits the full circuit DEM at gate boundaries. Each memory operation + becomes a segment; each transversal gate becomes a boundary gate with + Pauli frame propagation rules. + + Returns: + Dict with keys: segments, boundary_gates, num_observables, full_dem. + """ + # Build the full DEM + full_dem = self.build_dem(p1=p1, p2=p2, p_meas=p_meas, p_prep=p_prep) + sc = self.stab_coords() + + # Parse detector time coordinates from full DEM + det_times = {} + for line in full_dem.split("\n"): + line = line.strip() + if line.startswith("detector("): + paren = line.index(")") + coords = [float(x) for x in line[len("detector(") : paren].split(",")] + tokens = line[paren + 1 :].split() + for tok in tokens: + if tok.startswith("D"): + det_id = int(tok[1:]) + det_times[det_id] = coords[-1] if coords else 0.0 + + # Compute segment time boundaries from operations. + # Each MEMORY op has a number of rounds. Time coordinates are + # sequential round indices across all segments. + segments = [] + boundary_gates = [] + # Gates accumulate between consecutive MEMORY ops. + pending_gates = [] + time_cursor = 0.0 + patch_labels = list(self._patches.keys()) + num_patches = len(patch_labels) + + # Track X/Z swap state per patch for stab_coords. + # After transversal H, the X and Z stabilizer types swap. + x_z_swapped = dict.fromkeys(patch_labels, False) + + for i, op in enumerate(self._operations): + if op.gate_type == LogicalGateType.MEMORY: + # If there are pending gates, they form the boundary + # between the previous segment and this one. + if segments and pending_gates: + boundary_gates.append(pending_gates) + pending_gates = [] + elif segments: + # No gate between segments — empty boundary + boundary_gates.append([]) + pending_gates = [] + seg_start = time_cursor + seg_end = time_cursor + op.rounds + time_cursor = seg_end + + # Find detectors in this time range, extended by buffer. + # Buffer extends the window into adjacent segments for + # cross-boundary error correlation context. + buf_start = max(0, seg_start - buffer) + buf_end = seg_end + buffer + + is_last = all( + self._operations[j].gate_type != LogicalGateType.MEMORY for j in range(i + 1, len(self._operations)) + ) + if is_last: + seg_det_ids = sorted(d for d, t in det_times.items() if t >= buf_start) + else: + seg_det_ids = sorted(d for d, t in det_times.items() if buf_start <= t < buf_end) + + # Build per-segment stab_coords respecting X/Z swap state + seg_sc = [] + for label in patch_labels: + base = sc[patch_labels.index(label)] + if x_z_swapped[label]: + # Swap X and Z positions + seg_sc.append({"X": base["Z"], "Z": base["X"]}) + else: + seg_sc.append({"X": base["X"], "Z": base["Z"]}) + + segments.append( + { + "det_ids": seg_det_ids, + "num_detectors": len(seg_det_ids), + "time_start": seg_start, + "time_end": seg_end, + "stab_coords": seg_sc, + } + ) + + elif op.gate_type == LogicalGateType.TRANSVERSAL_H: + label = op.patches[0] + idx = patch_labels.index(label) + pending_gates.append( + { + "type": "Hadamard", + "x_obs_bit": idx * 2, + "z_obs_bit": idx * 2 + 1, + } + ) + x_z_swapped[label] = not x_z_swapped[label] + + elif op.gate_type == LogicalGateType.TRANSVERSAL_CX: + ctrl_label, tgt_label = op.patches[0], op.patches[1] + ctrl_idx = patch_labels.index(ctrl_label) + tgt_idx = patch_labels.index(tgt_label) + if op.injection_type == "T": + pending_gates.append( + { + "type": "TGateInjection", + "z_obs_bit": ctrl_idx * 2 + 1, + "ancilla_z_bit": tgt_idx * 2 + 1, + } + ) + else: + pending_gates.append( + { + "type": "Cnot", + "ctrl_x_bit": ctrl_idx * 2, + "ctrl_z_bit": ctrl_idx * 2 + 1, + "tgt_x_bit": tgt_idx * 2, + "tgt_z_bit": tgt_idx * 2 + 1, + } + ) + + elif op.gate_type in (LogicalGateType.TRANSVERSAL_SZ, LogicalGateType.TRANSVERSAL_SZdg): + label = op.patches[0] + idx = patch_labels.index(label) + pending_gates.append( + { + "type": "SGate", + "x_obs_bit": idx * 2, + "z_obs_bit": idx * 2 + 1, + } + ) + + # Build per-segment sub-DEMs by filtering the full DEM. + # Each segment gets only the mechanisms involving its detectors. + seg_dems = [] + for seg in segments: + det_set = set(seg["det_ids"]) + # Build local detector index mapping + global_to_local = {g: l for l, g in enumerate(seg["det_ids"])} + + lines = [] + # Add detector coordinate declarations + for line in full_dem.split("\n"): + line = line.strip() + if line.startswith("detector("): + paren = line.index(")") + tokens = line[paren + 1 :].split() + for tok in tokens: + if tok.startswith("D"): + d_id = int(tok[1:]) + if d_id in global_to_local: + local = global_to_local[d_id] + coords = line[len("detector(") : paren] + lines.append(f"detector({coords}) D{local}") + + # Add error mechanisms (remap detector IDs) + for line in full_dem.split("\n"): + line = line.strip() + if not line.startswith("error("): + continue + tokens = line.split() + prob_tok = tokens[0] + new_tokens = [prob_tok] + has_local_det = False + for tok in tokens[1:]: + if tok.startswith("D"): + d_id = int(tok[1:]) + if d_id in global_to_local: + new_tokens.append(f"D{global_to_local[d_id]}") + has_local_det = True + elif tok.startswith("L"): + new_tokens.append(tok) + if has_local_det: + lines.append(" ".join(new_tokens)) + + seg_dems.append("\n".join(lines)) + + return { + "segments": [ + { + "dem": seg_dems[i], + "num_detectors": segments[i]["num_detectors"], + "stab_coords": segments[i]["stab_coords"], + } + for i in range(len(segments)) + ], + "boundary_gates": boundary_gates, + "num_observables": num_patches * 2, + "full_dem": full_dem, + } + + def build_decoder( + self, + *, + p1: float = 0.001, + p2: float = 0.001, + p_meas: float = 0.001, + p_prep: float = 0.0, + inner_decoder: str = "fusion_blossom_serial", + use_stim_dem: bool = True, + ): + """Build an ObservableSubgraphDecoder for this circuit. + + Args: + p1: Single-qubit depolarizing error rate. + p2: Two-qubit depolarizing error rate. + p_meas: Measurement error rate. + p_prep: Preparation error rate. + inner_decoder: Decoder type for each subgraph. + use_stim_dem: If True, use Stim for DEM generation (more error + mechanisms). If False, use PECOS-native DEM pipeline. + + Returns: + Tuple of (stim.Circuit, ObservableSubgraphDecoder). + """ + import stim + from pecos_rslib.qec import ObservableSubgraphDecoder + + stim_str = self.to_stim(p1=p1, p2=p2, p_meas=p_meas, p_prep=p_prep) + circuit = stim.Circuit(stim_str) + + if use_stim_dem: + dem = circuit.detector_error_model(ignore_decomposition_failures=True) + dem_str = str(dem) + else: + dem_str = self.build_dem(p1=p1, p2=p2, p_meas=p_meas, p_prep=p_prep) + + sc = self.stab_coords() + decoder = ObservableSubgraphDecoder(dem_str, sc, inner_decoder) + return circuit, decoder + + +class _CircuitGenerator: + """Internal: generates a PECOS TickCircuit for logical circuits. + + Builds a TickCircuit with detector and observable annotations as + JSON metadata. The TickCircuit is the source of truth; Stim circuit + strings are derived from it via tick_circuit_to_stim(). + """ + + def __init__( + self, + patches: dict[str, PatchState], + operations: list[LogicalOp], + ) -> None: + from pecos_rslib.quantum import TickCircuit + + self.patches = patches + self.operations = operations + + self.tc = TickCircuit() + self._current_tick = None + self._allocated: set[int] = set() + self.meas_count = 0 + + self.stab_meas: dict[tuple[str, str, int, int, int], int] = {} + self.data_meas: dict[tuple[str, int], int] = {} + + self.segment_idx = 0 + self.next_observable_idx = 0 + self.round_time = 0.0 + + self._det_json: list[dict] = [] + self._obs_json: list[dict] = [] + + def _new_tick(self): + self._current_tick = self.tc.tick() + return self._current_tick + + def _tick(self): + if self._current_tick is None: + return self._new_tick() + return self._current_tick + + def _end_tick(self): + self._current_tick = None + + def _emit_qalloc_or_reset(self, qubits: list[int]) -> None: + t = self._tick() + new_qs = [q for q in qubits if q not in self._allocated] + old_qs = [q for q in qubits if q in self._allocated] + if new_qs: + t.qalloc(new_qs) + self._allocated.update(new_qs) + if old_qs: + t.pz(old_qs) + + def generate(self): + """Generate the TickCircuit with detector/observable metadata.""" + import json + + is_first = True + # Per-patch last memory index: for each patch, the last MEMORY + # operation that includes it. This ensures each patch gets its + # final measurement emitted in the correct segment. + last_mem_for_patch: dict[str, int] = {} + for i, op in enumerate(self.operations): + if op.gate_type == LogicalGateType.MEMORY: + for label in op.patches: + last_mem_for_patch[label] = i + + for op_idx, op in enumerate(self.operations): + if op.gate_type == LogicalGateType.MEMORY: + # A patch is "last" in this segment if this is its last memory op. + last_patches = {label for label in op.patches if last_mem_for_patch.get(label) == op_idx} + self._emit_memory_segment( + op, + is_first=is_first, + is_last=bool(last_patches), + last_patches=last_patches, + ) + is_first = False + self.segment_idx += 1 + + elif op.gate_type == LogicalGateType.TRANSVERSAL_H: + self._emit_transversal_h(op) + + elif op.gate_type == LogicalGateType.TRANSVERSAL_SZ: + self._emit_transversal_sz(op) + + elif op.gate_type == LogicalGateType.TRANSVERSAL_SZdg: + self._emit_transversal_szdg(op) + + elif op.gate_type == LogicalGateType.TRANSVERSAL_CX: + self._emit_transversal_cx(op) + + # Build detector/observable definitions with both formats: + # - "records": negative offsets (Stim compatibility, legacy) + # - "meas_ids": absolute MeasResult IDs (stable, preferred) + total = self.meas_count + det_out = [ + { + "id": d["id"], + "coords": d["coords"], + "records": [idx - total for idx in d["abs_records"]], + "meas_ids": d["abs_records"], + } + for d in self._det_json + ] + obs_out = [ + { + "id": o["id"], + "records": [idx - total for idx in o["abs_records"]], + "meas_ids": o["abs_records"], + } + for o in self._obs_json + ] + + self.tc.set_meta("detectors", json.dumps(det_out)) + self.tc.set_meta("observables", json.dumps(obs_out)) + self.tc.set_meta("num_measurements", str(total)) + return self.tc + + def _first_memory_basis(self, patch_label: str | None = None) -> str: + """Basis of the first memory segment (prep basis).""" + for op in self.operations: + if op.gate_type == LogicalGateType.MEMORY: + if patch_label and patch_label in op.per_patch_basis: + return op.per_patch_basis[patch_label] + return op.basis + return "Z" + + def _last_memory_basis(self, patch_label: str | None = None) -> str: + """Basis of the last memory segment (measurement basis).""" + last = "Z" + for op in self.operations: + if op.gate_type == LogicalGateType.MEMORY: + if patch_label and patch_label in op.per_patch_basis: + last = op.per_patch_basis[patch_label] + else: + last = op.basis + return last + + def _emit_meas(self, qubits: list[int]) -> list[int]: + self._tick().mz(qubits) + indices = list(range(self.meas_count, self.meas_count + len(qubits))) + self.meas_count += len(qubits) + return indices + + def _emit_final_meas(self, qubits: list[int]) -> list[int]: + self._tick().mz(qubits) + indices = list(range(self.meas_count, self.meas_count + len(qubits))) + self.meas_count += len(qubits) + return indices + + def _rec(self, abs_idx: int) -> int: + return abs_idx - self.meas_count + + def _data_qubits(self, patch_label: str) -> list[int]: + ps = self.patches[patch_label] + return [ps.qubit_offset + i for i in range(ps.patch.geometry.num_data)] + + def _emit_memory_segment( + self, + op: LogicalOp, + *, + is_first: bool, + is_last: bool, + last_patches: set[str] | None = None, + ) -> None: + """Emit syndrome extraction rounds for one or more patches.""" + from pecos.qec.surface.schedule import compute_cnot_schedule + + num_rounds = op.rounds + + # Precompute per-patch data + patch_info = [] + for patch_label in op.patches: + ps = self.patches[patch_label] + patch = ps.patch + geom = patch.geometry + offset = ps.qubit_offset + num_x = len(geom.x_stabilizers) + num_z = len(geom.z_stabilizers) + anc_base = offset + geom.num_data + + if ps.x_z_swapped: + x_anc_qs = [anc_base + num_x + i for i in range(num_z)] + z_anc_qs = [anc_base + i for i in range(num_x)] + current_x_stabs = geom.z_stabilizers + current_z_stabs = geom.x_stabilizers + else: + x_anc_qs = [anc_base + i for i in range(num_x)] + z_anc_qs = [anc_base + num_x + i for i in range(num_z)] + current_x_stabs = geom.x_stabilizers + current_z_stabs = geom.z_stabilizers + + patch_info.append( + { + "label": patch_label, + "ps": ps, + "geom": geom, + "offset": offset, + "num_x": num_x, + "anc_base": anc_base, + "data_qs": [offset + i for i in range(geom.num_data)], + "x_anc_qs": x_anc_qs, + "z_anc_qs": z_anc_qs, + "current_x_stabs": current_x_stabs, + "current_z_stabs": current_z_stabs, + "schedule": compute_cnot_schedule(patch), + } + ) + + # Initialization — per-patch basis + if is_first: + t = self._new_tick() + for pi in patch_info: + self._emit_qalloc_or_reset(pi["data_qs"]) + self._end_tick() + + need_h = [] + need_hs = [] + for pi in patch_info: + pb = op.per_patch_basis.get(pi["label"], op.basis) + if pb == "X": + need_h.extend(pi["data_qs"]) + elif pb == "Y": + need_hs.extend(pi["data_qs"]) + + if need_h or need_hs: + t = self._new_tick() + if need_h: + t.h(need_h) + if need_hs: + t.h(need_hs) + self._end_tick() + if need_hs: + t = self._new_tick() + t.sz(need_hs) + self._end_tick() + + # Syndrome extraction rounds + for rnd in range(num_rounds): + # Reset ancillas + t = self._new_tick() + for pi in patch_info: + self._emit_qalloc_or_reset(pi["x_anc_qs"] + pi["z_anc_qs"]) + self._end_tick() + + # H on X-type ancillas + all_x_anc = [q for pi in patch_info for q in pi["x_anc_qs"]] + t = self._new_tick() + t.h(all_x_anc) + self._end_tick() + + # CX rounds + num_cx_rounds = max(len(pi["schedule"]) for pi in patch_info) + for cx_round_idx in range(num_cx_rounds): + all_pairs = [] + for pi in patch_info: + if cx_round_idx >= len(pi["schedule"]): + continue + for phys_type, stab_idx, data_idx in pi["schedule"][cx_round_idx]: + data_q = pi["offset"] + data_idx + if phys_type == "X": + anc_q = pi["anc_base"] + stab_idx + else: + anc_q = pi["anc_base"] + pi["num_x"] + stab_idx + currently_x = (phys_type == "X") != pi["ps"].x_z_swapped + if currently_x: + all_pairs.append((anc_q, data_q)) + else: + all_pairs.append((data_q, anc_q)) + t = self._new_tick() + if all_pairs: + t.cx(all_pairs) + self._end_tick() + + # H on X-type ancillas + t = self._new_tick() + t.h(all_x_anc) + self._end_tick() + + # Measure ancillas + t = self._new_tick() + for pi in patch_info: + x_meas = self._emit_meas(pi["x_anc_qs"]) + z_meas = self._emit_meas(pi["z_anc_qs"]) + for i, s in enumerate(pi["current_x_stabs"]): + self.stab_meas[(pi["label"], "X", s.index, self.segment_idx, rnd)] = x_meas[i] + for i, s in enumerate(pi["current_z_stabs"]): + self.stab_meas[(pi["label"], "Z", s.index, self.segment_idx, rnd)] = z_meas[i] + # Invalidate _last_round_cache since stab_meas changed + if hasattr(self, "_last_round_cache"): + del self._last_round_cache + self._end_tick() + + # Detectors + for pi in patch_info: + self._emit_round_detectors(pi["label"], rnd, is_first_segment=is_first) + + self.round_time += 1.0 + + # Final measurement: two phases so cross-patch observable + # references work (all data measurements must exist before + # any observable is emitted). + if is_last and last_patches: + final_patches = [pi for pi in patch_info if pi["label"] in last_patches] + for pi in final_patches: + self._emit_final_data_measurements(pi["label"]) + for pi in final_patches: + self._emit_final_detectors_and_observables(pi["label"]) + + def _emit_round_detectors( + self, + patch_label: str, + round_idx: int, + *, + is_first_segment: bool, + ) -> None: + """Emit detectors for one syndrome round. + + Handles three cases: + 1. First round of first segment: only basis-matching stabs are deterministic + 2. First round after a gate boundary: cross-type comparison needed + 3. Normal round: compare same-type measurements in consecutive rounds + """ + ps = self.patches[patch_label] + geom = ps.patch.geometry + seg = self.segment_idx + + for stab_type in ["X", "Z"]: + stabs = geom.x_stabilizers if stab_type == "X" else geom.z_stabilizers + for s in stabs: + curr_key = (patch_label, stab_type, s.index, seg, round_idx) + curr_idx = self.stab_meas.get(curr_key) + if curr_idx is None: + continue + + if round_idx == 0 and is_first_segment and seg == 0: + # First round of very first segment: + # Only stabilizers matching the prep basis are deterministic. + # Find the prep basis from the first memory operation. + init_basis = self._first_memory_basis(patch_label) + det_type = "Z" if init_basis == "Z" else "X" + # Account for X/Z swap + effective_type = stab_type + if ps.x_z_swapped: + effective_type = "Z" if stab_type == "X" else "X" + if effective_type == det_type: + self._add_detector( + patch_label, + stab_type, + s.index, + [curr_idx], + ) + + elif round_idx == 0 and seg > 0: + # First round after a gate boundary. + # Need to find the matching measurement from the previous segment. + self._emit_boundary_detector(patch_label, stab_type, s.index, curr_idx) + + elif round_idx > 0: + # Normal: compare with previous round in same segment + prev_key = (patch_label, stab_type, s.index, seg, round_idx - 1) + prev_idx = self.stab_meas.get(prev_key) + if prev_idx is not None: + self._add_detector( + patch_label, + stab_type, + s.index, + [curr_idx, prev_idx], + ) + + def _emit_boundary_detector( + self, + patch_label: str, + stab_type: str, + stab_index: int, + curr_meas_idx: int, + ) -> None: + """Emit a detector at a gate boundary. + + After transversal H: an X-check in the new segment corresponds to what + was a Z-check in the previous segment (and vice versa). The detector + compares the current measurement with the last measurement of the + *conjugated* type from the previous segment. + """ + ps = self.patches[patch_label] + prev_seg = self.segment_idx - 1 + + # Find the gate that affects this specific patch at this boundary + gate_op = self._find_gate_before_segment(self.segment_idx, patch_label) + + if ( + gate_op is not None + and gate_op.gate_type == LogicalGateType.TRANSVERSAL_H + and patch_label in gate_op.patches + ): + # After H on THIS patch: X-stabs were Z-stabs, Z-stabs were X-stabs + conjugated_type = "Z" if stab_type == "X" else "X" + # Find the last round of the previous segment + prev_last_round = self._last_round_of_segment(patch_label, conjugated_type, prev_seg) + if prev_last_round is not None: + prev_key = (patch_label, conjugated_type, stab_index, prev_seg, prev_last_round) + prev_idx = self.stab_meas.get(prev_key) + if prev_idx is not None: + self._add_detector( + patch_label, + stab_type, + stab_index, + [curr_meas_idx, prev_idx], + ) + # If no previous measurement found, this stabilizer wasn't measured before + # (e.g., it's the non-deterministic type). No detector. + + elif ( + gate_op is not None + and gate_op.gate_type == LogicalGateType.TRANSVERSAL_CX + and patch_label in gate_op.patches + ): + # After CX(control, target): + # Control X-stabs: propagated to target → 3-body detector + # post_ctrl_X XOR pre_ctrl_X XOR pre_tgt_X + # Target Z-stabs: propagated back to control → 3-body detector + # post_tgt_Z XOR pre_tgt_Z XOR pre_ctrl_Z + # Control Z-stabs: unchanged → normal 2-body detector + # Target X-stabs: unchanged → normal 2-body detector + ctrl_label = gate_op.patches[0] + tgt_label = gate_op.patches[1] + is_control = patch_label == ctrl_label + + prev_last_round = self._last_round_of_segment(patch_label, stab_type, prev_seg) + if prev_last_round is None: + return # No previous measurement + + prev_key = (patch_label, stab_type, stab_index, prev_seg, prev_last_round) + prev_idx = self.stab_meas.get(prev_key) + if prev_idx is None: + return + + needs_cross_patch = (is_control and stab_type == "X") or (not is_control and stab_type == "Z") + + if needs_cross_patch: + # 3-body detector: also include the other patch's measurement + other_label = tgt_label if is_control else ctrl_label + other_last_round = self._last_round_of_segment(other_label, stab_type, prev_seg) + if other_last_round is not None: + other_key = (other_label, stab_type, stab_index, prev_seg, other_last_round) + other_idx = self.stab_meas.get(other_key) + if other_idx is not None: + self._add_detector( + patch_label, + stab_type, + stab_index, + [curr_meas_idx, prev_idx, other_idx], + ) + return + # Fall through to 2-body if cross-patch measurement not found + self._add_detector( + patch_label, + stab_type, + stab_index, + [curr_meas_idx, prev_idx], + ) + + else: + # No gate boundary — normal comparison with previous segment + prev_last_round = self._last_round_of_segment(patch_label, stab_type, prev_seg) + if prev_last_round is not None: + prev_key = (patch_label, stab_type, stab_index, prev_seg, prev_last_round) + prev_idx = self.stab_meas.get(prev_key) + if prev_idx is not None: + self._add_detector( + patch_label, + stab_type, + stab_index, + [curr_meas_idx, prev_idx], + ) + + def _find_gate_before_segment( + self, + segment_idx: int, + patch_label: str | None = None, + ) -> LogicalOp | None: + """Find the gate operation that precedes a memory segment. + + If patch_label is given, returns the gate that affects that specific + patch (checking gate_op.patches). This handles the case where multiple + gates are stacked between segments (e.g., H on A then H on B). + """ + mem_count = 0 + for i, op in enumerate(self.operations): + if op.gate_type == LogicalGateType.MEMORY: + if mem_count == segment_idx: + # Look backwards for gates + for j in range(i - 1, -1, -1): + if self.operations[j].gate_type == LogicalGateType.MEMORY: + break + if patch_label is None: + return self.operations[j] + if patch_label in self.operations[j].patches: + return self.operations[j] + return None + mem_count += 1 + return None + + def _last_round_of_segment(self, patch_label: str, stab_type: str, seg_idx: int) -> int | None: + """Find the last round index for a stabilizer type in a segment. + + Uses a cached index built on first call, then O(1) lookups. + """ + if not hasattr(self, "_last_round_cache"): + # Build cache from stab_meas keys: (patch, type, seg) → max_round + cache: dict[tuple[str, str, int], int] = {} + for patch, stype, _sidx, seg, rnd in self.stab_meas: + key = (patch, stype, seg) + if key not in cache or rnd > cache[key]: + cache[key] = rnd + self._last_round_cache = cache + return self._last_round_cache.get((patch_label, stab_type, seg_idx)) + + def _ancilla_spatial_coords( + self, + patch_label: str, + stab_type: str, + stab_index: int, + ) -> tuple[float, float]: + """Compute the spatial position of a stabilizer's ancilla. + + Returns (x, y) including the patch's coord_offset, using the + average position of the stabilizer's data qubits. + """ + ps = self.patches[patch_label] + geom = ps.patch.geometry + cx, cy = ps.coord_offset + stabs = geom.x_stabilizers if stab_type == "X" else geom.z_stabilizers + s = stabs[stab_index] + positions = [geom.id_to_pos[q] for q in s.data_qubits] + avg_row = sum(r for r, c in positions) / len(positions) + avg_col = sum(c for r, c in positions) / len(positions) + return (avg_col * 2 + cx, avg_row * 2 + cy) + + def _add_detector( + self, + patch_label: str, + stab_type: str, + stab_index: int, + meas_indices: list[int], + ) -> None: + anc_x, anc_y = self._ancilla_spatial_coords(patch_label, stab_type, stab_index) + # Store absolute indices; convert to relative offsets in generate() + self._det_json.append( + { + "id": len(self._det_json), + "coords": [anc_x, anc_y, self.round_time], + "abs_records": list(meas_indices), + } + ) + + def _emit_transversal_h(self, op: LogicalOp) -> None: + ps = self.patches[op.patches[0]] + t = self._new_tick() + t.h(self._data_qubits(op.patches[0])) + self._end_tick() + ps.x_z_swapped = not ps.x_z_swapped + + def _emit_transversal_sz(self, op: LogicalOp) -> None: + t = self._new_tick() + t.sz(self._data_qubits(op.patches[0])) + self._end_tick() + + def _emit_transversal_szdg(self, op: LogicalOp) -> None: + t = self._new_tick() + t.szdg(self._data_qubits(op.patches[0])) + self._end_tick() + + def _emit_transversal_cx(self, op: LogicalOp) -> None: + ctrl_label, tgt_label = op.patches[0], op.patches[1] + ctrl_ps = self.patches[ctrl_label] + tgt_ps = self.patches[tgt_label] + + if ctrl_ps.x_z_swapped != tgt_ps.x_z_swapped: + msg = ( + f"Transversal CX requires same stabilizer orientation. " + f"'{ctrl_label}' swapped={ctrl_ps.x_z_swapped}, " + f"'{tgt_label}' swapped={tgt_ps.x_z_swapped}." + ) + raise ValueError(msg) + + pairs = list(zip(self._data_qubits(ctrl_label), self._data_qubits(tgt_label))) + t = self._new_tick() + t.cx(pairs) + self._end_tick() + + if op.teleportation: + ctrl_ps.z_obs_includes.append(tgt_label) + + # Track entanglement: CX spreads X on control to target, + # and Z on target to control. + ctrl_ps.x_entangled_with.append(tgt_label) + tgt_ps.z_entangled_with.append(ctrl_label) + + def _emit_final_data_measurements(self, patch_label: str) -> None: + ps = self.patches[patch_label] + geom = ps.patch.geometry + data_qs = self._data_qubits(patch_label) + meas_basis = self._last_memory_basis(patch_label) + + if meas_basis == "X": + t = self._new_tick() + t.h(data_qs) + self._end_tick() + + t = self._new_tick() + meas_indices = self._emit_final_meas(data_qs) + self._end_tick() + for i, q in enumerate(range(geom.num_data)): + self.data_meas[(patch_label, q)] = meas_indices[i] + + def _emit_final_detectors_and_observables(self, patch_label: str) -> None: + ps = self.patches[patch_label] + geom = ps.patch.geometry + meas_basis = self._last_memory_basis(patch_label) + + if meas_basis == "Z": + final_stabs = geom.x_stabilizers if ps.x_z_swapped else geom.z_stabilizers + lookup_type = "Z" + else: + final_stabs = geom.z_stabilizers if ps.x_z_swapped else geom.x_stabilizers + lookup_type = "X" + + if ps.x_z_swapped: + logical_op = geom.logical_z if meas_basis == "X" else geom.logical_x + else: + logical_op = geom.logical_x if meas_basis == "X" else geom.logical_z + + seg = self.segment_idx + last_rnd = self._last_round_of_segment(patch_label, lookup_type, seg) + + if last_rnd is not None: + for s in final_stabs: + data_rec = [self.data_meas[(patch_label, dq)] for dq in s.data_qubits] + syn_key = (patch_label, lookup_type, s.index, seg, last_rnd) + syn_idx = self.stab_meas.get(syn_key) + if syn_idx is not None: + all_idx = data_rec + [syn_idx] + anc_x, anc_y = self._ancilla_spatial_coords(patch_label, lookup_type, s.index) + self._det_json.append( + { + "id": len(self._det_json), + "coords": [anc_x, anc_y, self.round_time], + "abs_records": list(all_idx), + } + ) + + if logical_op is not None: + # Check if this observable is reliable given entanglement. + # After CX(ctrl, tgt): ctrl's X is entangled with tgt, + # tgt's Z is entangled with ctrl. + # An observable is reliable if: + # - Not entangled, OR + # - The entangled partner is measured in the same basis + entangled_with = ps.x_entangled_with if meas_basis == "X" else ps.z_entangled_with + is_reliable = True + for other_label in entangled_with: + other_basis = self._last_memory_basis(other_label) + if other_basis != meas_basis: + is_reliable = False + break + + if not is_reliable: + # Skip non-reliable observables — they're physically + # non-deterministic and would cause Stim DEM errors. + # The decoder handles these through the 3-body detectors. + self.next_observable_idx += 1 + return + + obs_idx = self.next_observable_idx + self.next_observable_idx += 1 + obs_indices = [self.data_meas[(patch_label, q)] for q in logical_op.data_qubits] + + # Teleportation corrections + for other_label in ps.z_obs_includes: + other_logical = self.patches[other_label].patch.geometry.logical_z + if other_logical is not None: + for q in other_logical.data_qubits: + key = (other_label, q) + if key in self.data_meas: + obs_indices.append(self.data_meas[key]) + + self._obs_json.append( + { + "id": obs_idx, + "abs_records": list(obs_indices), + } + ) diff --git a/python/quantum-pecos/src/pecos/qec/surface/patch.py b/python/quantum-pecos/src/pecos/qec/surface/patch.py index 0f05ed9c8..ef48dd28b 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/patch.py +++ b/python/quantum-pecos/src/pecos/qec/surface/patch.py @@ -7,9 +7,11 @@ with geometry stored as data structures. """ +from __future__ import annotations + from dataclasses import dataclass, field from enum import Enum, auto -from typing import TYPE_CHECKING +from typing import TYPE_CHECKING, TypedDict from pecos_rslib.num import zeros @@ -21,6 +23,7 @@ get_rotated_logical_x, get_rotated_logical_z, ) +from pecos.qec.surface.schedule import get_stab_schedule if TYPE_CHECKING: import pecos @@ -57,6 +60,115 @@ class LogicalOperator: data_qubits: tuple[int, ...] +class StabilizerScheduleEntry(TypedDict): + """Public metadata for one stabilizer schedule touch.""" + + round_0based: int + data_qubit: int + touch_label: str + + +class SurfacePatchDescriptor(TypedDict): + """Public summary of one surface-code patch.""" + + distance: int + dx: int + dz: int + rotated: bool + orientation: str + num_data: int + num_ancilla: int + num_qubits: int + + +class StabilizerDescriptor(TypedDict): + """Public descriptor for one stabilizer.""" + + stabilizer_kind: str + stabilizer_index: int + stabilizer_is_boundary: bool + stabilizer_region: str + schedule_rounds: list[int] + schedule_start_round: int | None + schedule_end_round: int | None + schedule_entries: list[StabilizerScheduleEntry] + data_qubits: list[int] + data_qubit_positions: list[list[int]] + weight: int + + +class LogicalDescriptor(TypedDict): + """Public descriptor for one logical operator.""" + + logical_type: str + data_qubits: list[int] + data_qubit_positions: list[list[int]] + weight: int + support_axis: str + + +def _get_stabilizer_region(stab: Stabilizer, patch: SurfacePatch) -> str: + """Return a coarse region label like ``top+left`` for a stabilizer.""" + geom = patch.geometry + positions = [geom.id_to_pos[q] for q in stab.data_qubits] + avg_row = sum(row for row, _ in positions) / len(positions) + avg_col = sum(col for _, col in positions) / len(positions) + row_label = "top" if avg_row < (geom.dx - 1) / 2 else "bottom" + col_label = "left" if avg_col < (geom.dz - 1) / 2 else "right" + return f"{row_label}+{col_label}" + + +def _get_stabilizer_touch_label(stab: Stabilizer, patch: SurfacePatch, data_qubit: int) -> str: + """Label how a data qubit sits relative to a stabilizer support.""" + geom = patch.geometry + if data_qubit not in stab.data_qubits: + msg = f"Qubit {data_qubit} is not in stabilizer {stab.stab_type}{stab.index}" + raise ValueError(msg) + + positions = [geom.id_to_pos[q] for q in stab.data_qubits] + data_row, data_col = geom.id_to_pos[data_qubit] + rows = [row for row, _ in positions] + cols = [col for _, col in positions] + + if len(set(rows)) == 1: + return "left" if data_col == min(cols) else "right" + if len(set(cols)) == 1: + return "top" if data_row == min(rows) else "bottom" + + vertical = "T" if data_row == min(rows) else "B" + horizontal = "L" if data_col == min(cols) else "R" + return vertical + horizontal + + +def _get_stabilizer_schedule_metadata(stab: Stabilizer, patch: SurfacePatch) -> dict[str, object]: + """Return metadata describing one stabilizer's schedule and geometry.""" + entries: list[StabilizerScheduleEntry] = [ + { + "round_0based": round_0based, + "data_qubit": data_qubit, + "touch_label": _get_stabilizer_touch_label(stab, patch, data_qubit), + } + for round_0based, data_qubit in get_stab_schedule( + stab.stab_type, + stab.data_qubits, + stab.is_boundary, + patch.dx, + patch.dz, + ) + ] + rounds = [int(entry["round_0based"]) for entry in entries] + return { + "stabilizer_kind": stab.stab_type, + "stabilizer_index": stab.index, + "stabilizer_is_boundary": stab.is_boundary, + "stabilizer_region": _get_stabilizer_region(stab, patch), + "schedule_rounds": rounds, + "schedule_start_round": rounds[0] if rounds else None, + "schedule_end_round": rounds[-1] if rounds else None, + "schedule_entries": entries, + } + + @dataclass class PatchGeometry: """Geometry of a surface code patch. @@ -102,12 +214,11 @@ def _generate_layout(self) -> None: self.id_to_pos[idx] = pos def _generate_stabilizers(self) -> None: - d = min(self.dx, self.dz) - if self.rotated: - x_supports = compute_rotated_x_stabilizers(d) - z_supports = compute_rotated_z_stabilizers(d) + x_supports = compute_rotated_x_stabilizers(self.dx, self.dz) + z_supports = compute_rotated_z_stabilizers(self.dx, self.dz) else: + d = min(self.dx, self.dz) x_supports = compute_x_stabilizer_supports(d) z_supports = compute_z_stabilizer_supports(d) @@ -135,11 +246,9 @@ def _generate_stabilizers(self) -> None: self.num_z_stab = len(self.z_stabilizers) def _generate_logical_operators(self) -> None: - d = min(self.dx, self.dz) - if self.rotated: - logical_x_qubits = get_rotated_logical_x(d) - logical_z_qubits = get_rotated_logical_z(d) + logical_x_qubits = get_rotated_logical_x(self.dx, self.dz) + logical_z_qubits = get_rotated_logical_z(self.dx, self.dz) else: logical_x_qubits = tuple(i * self.dz for i in range(self.dx)) logical_z_qubits = tuple(range(self.dz)) @@ -187,30 +296,37 @@ def create( orientation: PatchOrientation = PatchOrientation.X_TOP_BOTTOM, *, rotated: bool = True, - ) -> "SurfacePatch": + ) -> SurfacePatch: """Create a surface code patch. + Supports any positive dimensions: + - dx=dz=d (odd >= 3): standard surface code [[d^2, 1, d]] + - dx != dz: asymmetric surface code + - dx=1, dz=N: Z-repetition code [[N, 1, 1]] (N-1 X stabilizers) + - dx=N, dz=1: X-repetition code [[N, 1, 1]] (N-1 Z stabilizers) + - dx=dz=1: single physical qubit, no stabilizers + Args: - distance: Symmetric code distance (must be odd >= 3). - dx: X distance for asymmetric codes. - dz: Z distance for asymmetric codes. + distance: Symmetric code distance (>= 1). + dx: X distance (rows) for asymmetric codes (>= 1). + dz: Z distance (columns) for asymmetric codes (>= 1). orientation: Patch boundary orientation. rotated: If True (default), use the rotated layout which is more common and uses fewer qubits. If False, use the standard (non-rotated) layout. """ if distance is not None: - if distance < 3 or distance % 2 == 0: - msg = f"Distance must be odd >= 3, got {distance}" + if distance < 1: + msg = f"Distance must be >= 1, got {distance}" raise ValueError(msg) dx = dx or distance dz = dz or distance elif dx is not None and dz is not None: - if dx < 3 or dx % 2 == 0: - msg = f"dx must be odd >= 3, got {dx}" + if dx < 1: + msg = f"dx must be >= 1, got {dx}" raise ValueError(msg) - if dz < 3 or dz % 2 == 0: - msg = f"dz must be odd >= 3, got {dz}" + if dz < 1: + msg = f"dz must be >= 1, got {dz}" raise ValueError(msg) else: msg = "Must provide either distance or both dx and dz" @@ -259,7 +375,87 @@ def rotated(self) -> bool: """True if using rotated layout, False for standard layout.""" return self.geometry.rotated - def get_parity_matrix(self, stab_type: str) -> "pecos.Array": + @property + def num_ancilla(self) -> int: + """Number of ancilla qubits.""" + return self.geometry.num_ancilla + + def get_patch_descriptor(self) -> SurfacePatchDescriptor: + """Return a public metadata summary for this patch.""" + return { + "distance": self.distance, + "dx": self.dx, + "dz": self.dz, + "rotated": self.rotated, + "orientation": self.geometry.orientation.name, + "num_data": self.num_data, + "num_ancilla": self.num_ancilla, + "num_qubits": self.num_qubits, + } + + def get_stabilizer_descriptor( + self, + stab_type: str, + index: int, + ) -> StabilizerDescriptor: + """Return one public stabilizer descriptor.""" + stabs = self.x_stabilizers if stab_type.upper() == "X" else self.z_stabilizers + stab = stabs[index] + metadata = _get_stabilizer_schedule_metadata(stab, self) + positions = [list(self.geometry.id_to_pos[q]) for q in stab.data_qubits] + return { + **metadata, + "data_qubits": list(stab.data_qubits), + "data_qubit_positions": positions, + "weight": stab.weight, + } + + def iter_stabilizer_descriptors( + self, + stab_type: str | None = None, + ) -> list[StabilizerDescriptor]: + """Iterate over public stabilizer descriptors.""" + if stab_type is None: + descriptors: list[StabilizerDescriptor] = [] + descriptors.extend(self.iter_stabilizer_descriptors("X")) + descriptors.extend(self.iter_stabilizer_descriptors("Z")) + return descriptors + + kind = stab_type.upper() + stabs = self.x_stabilizers if kind == "X" else self.z_stabilizers + return [self.get_stabilizer_descriptor(kind, stab.index) for stab in stabs] + + def get_logical_descriptor(self, logical_type: str) -> LogicalDescriptor: + """Return one public logical-operator descriptor.""" + kind = logical_type.upper() + logical = self.geometry.logical_x if kind == "X" else self.geometry.logical_z + if logical is None: + msg = f"Logical operator {kind} is not available" + raise ValueError(msg) + + positions = [list(self.geometry.id_to_pos[q]) for q in logical.data_qubits] + rows = {row for row, _ in map(tuple, positions)} + cols = {col for _, col in map(tuple, positions)} + support_axis = "vertical" if len(cols) == 1 else "horizontal" + if len(rows) == 1 and len(cols) != 1: + support_axis = "horizontal" + + return { + "logical_type": logical.op_type, + "data_qubits": list(logical.data_qubits), + "data_qubit_positions": positions, + "weight": len(logical.data_qubits), + "support_axis": support_axis, + } + + def iter_logical_descriptors(self) -> list[LogicalDescriptor]: + """Iterate over logical descriptors in X, Z order.""" + return [ + self.get_logical_descriptor("X"), + self.get_logical_descriptor("Z"), + ] + + def get_parity_matrix(self, stab_type: str) -> pecos.Array: """Get parity check matrix.""" stabs = self.x_stabilizers if stab_type == "X" else self.z_stabilizers num_stab = len(stabs) @@ -293,23 +489,23 @@ def __init__(self) -> None: self._orientation: PatchOrientation = PatchOrientation.X_TOP_BOTTOM self._rotated: bool = True - def with_distance(self, distance: int) -> "SurfacePatchBuilder": + def with_distance(self, distance: int) -> SurfacePatchBuilder: """Set symmetric distance.""" self._distance = distance return self - def with_distances(self, dx: int, dz: int) -> "SurfacePatchBuilder": + def with_distances(self, dx: int, dz: int) -> SurfacePatchBuilder: """Set asymmetric distances.""" self._dx = dx self._dz = dz return self - def with_orientation(self, orientation: PatchOrientation) -> "SurfacePatchBuilder": + def with_orientation(self, orientation: PatchOrientation) -> SurfacePatchBuilder: """Set patch orientation.""" self._orientation = orientation return self - def rotated(self) -> "SurfacePatchBuilder": + def rotated(self) -> SurfacePatchBuilder: """Use rotated surface code layout (default). The rotated layout is more common and uses fewer physical qubits @@ -318,7 +514,7 @@ def rotated(self) -> "SurfacePatchBuilder": self._rotated = True return self - def standard(self) -> "SurfacePatchBuilder": + def standard(self) -> SurfacePatchBuilder: """Use standard (non-rotated) surface code layout. The standard layout uses more physical qubits but may be preferred diff --git a/python/quantum-pecos/src/pecos/qec/surface/plot.py b/python/quantum-pecos/src/pecos/qec/surface/plot.py index 2a30134f4..d02bf9345 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/plot.py +++ b/python/quantum-pecos/src/pecos/qec/surface/plot.py @@ -136,6 +136,7 @@ def _annotate_cnot_order(ax: plt.Axes, stabilizers: list, d: int) -> None: stab.data_qubits, stab.is_boundary, d, + d, ) # Compute centroid of the stabilizer diff --git a/python/quantum-pecos/src/pecos/qec/surface/schedule.py b/python/quantum-pecos/src/pecos/qec/surface/schedule.py index 410dd9ac6..8972fc934 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/schedule.py +++ b/python/quantum-pecos/src/pecos/qec/surface/schedule.py @@ -31,28 +31,28 @@ from pecos.qec.surface.patch import SurfacePatch -def _classify_boundary(stab_type: str, data_qubits: tuple[int, ...], d: int) -> str: +def _classify_boundary(stab_type: str, data_qubits: tuple[int, ...], dx: int, dz: int) -> str: """Classify which boundary a weight-2 stabilizer sits on. Returns one of: 'top', 'bottom', 'left', 'right'. """ - rows = [q // d for q in data_qubits] - cols = [q % d for q in data_qubits] + rows = [q // dz for q in data_qubits] + cols = [q % dz for q in data_qubits] if stab_type == "X": # X boundaries are top and bottom if all(r == 0 for r in rows): return "top" - if all(r == d - 1 for r in rows): + if all(r == dx - 1 for r in rows): return "bottom" else: # Z boundaries are left and right - if all(c == d - 1 for c in cols): + if all(c == dz - 1 for c in cols): return "right" if all(c == 0 for c in cols): return "left" - msg = f"Cannot classify boundary for {stab_type} stab with qubits {data_qubits} (d={d})" + msg = f"Cannot classify boundary for {stab_type} stab with qubits {data_qubits} (dx={dx}, dz={dz})" raise ValueError(msg) @@ -60,7 +60,8 @@ def get_stab_schedule( stab_type: str, data_qubits: tuple[int, ...], is_boundary: bool, - d: int, + dx: int, + dz: int, ) -> list[tuple[int, int]]: """Compute the per-stabilizer CNOT schedule. @@ -69,7 +70,8 @@ def get_stab_schedule( data_qubits: Tuple of data qubit IDs. For bulk (weight 4): (TL, TR, BL, BR). For boundary (weight 2): two qubits. is_boundary: Whether this is a boundary stabilizer. - d: Code distance. + dx: Number of rows (X distance). + dz: Number of columns (Z distance). Returns: List of (round_0based, data_qubit) pairs, sorted by round. @@ -82,7 +84,7 @@ def get_stab_schedule( return [(0, tr), (1, br), (2, tl), (3, bl)] # Boundary weight-2 stabilizer - boundary = _classify_boundary(stab_type, data_qubits, d) + boundary = _classify_boundary(stab_type, data_qubits, dx, dz) if boundary == "bottom": # Bottom X: rounds 0,1 -- right first then left @@ -115,16 +117,17 @@ def compute_cnot_schedule(patch: SurfacePatch) -> list[list[tuple[str, int, int] List of 4 rounds, each a list of (stab_type, stab_index, data_qubit) tuples representing CX gates to execute in parallel. """ - d = patch.distance + dx = patch.dx + dz = patch.dz rounds: list[list[tuple[str, int, int]]] = [[] for _ in range(4)] for stab in patch.x_stabilizers: - schedule = get_stab_schedule("X", stab.data_qubits, stab.is_boundary, d) + schedule = get_stab_schedule("X", stab.data_qubits, stab.is_boundary, dx, dz) for rnd, data_q in schedule: rounds[rnd].append(("X", stab.index, data_q)) for stab in patch.z_stabilizers: - schedule = get_stab_schedule("Z", stab.data_qubits, stab.is_boundary, d) + schedule = get_stab_schedule("Z", stab.data_qubits, stab.is_boundary, dx, dz) for rnd, data_q in schedule: rounds[rnd].append(("Z", stab.index, data_q)) diff --git a/python/quantum-pecos/src/pecos/simulators/__init__.py b/python/quantum-pecos/src/pecos/simulators/__init__.py index 15cd77263..a804c43b4 100644 --- a/python/quantum-pecos/src/pecos/simulators/__init__.py +++ b/python/quantum-pecos/src/pecos/simulators/__init__.py @@ -18,22 +18,23 @@ # Rust simulators (direct exports without Python wrappers) # Simulator engine builder factory functions -from pecos_rslib import clifford_rz, coin_toss, density_matrix, sparse_stab, stabilizer, state_vector -from pecos_rslib.simulators import CliffordRz, SparseStab, Stabilizer +from pecos_rslib import ( + coin_toss, + density_matrix, + sparse_stab, + stab_vec, + stabilizer, + state_vector, +) +from pecos_rslib.simulators import SparseStab, Stabilizer, StabVec from pecos.simulators import sim_class_types - -# Coin toss simulator (uses Rust backend) from pecos.simulators.cointoss import CoinToss - -# Ignores quantum gates, coin toss for measurements from pecos.simulators.default_simulator import DefaultSimulator from pecos.simulators.pauliprop import ( PauliFaultProp, # Backward compatibility PauliProp, ) - -# Pauli fault propagation sim from pecos.simulators.sparsestab import ( SparseStabPy as SparseStabPy, ) @@ -71,28 +72,23 @@ __all__ = [ "MPS", - # Rust simulators - "CliffordRz", - # Python simulators "CoinToss", "CuStateVec", "CudaStabilizer", - # CUDA simulators (Rust cuQuantum bindings) "CudaStateVec", "DefaultSimulator", "PauliFaultProp", "PauliProp", "SparseStab", "SparseStabPy", + "StabVec", "Stabilizer", "StateVec", - # Factory functions - "clifford_rz", "coin_toss", "density_matrix", - # Submodules "sim_class_types", "sparse_stab", + "stab_vec", "stabilizer", "state_vector", ] diff --git a/python/quantum-pecos/src/pecos/typing.py b/python/quantum-pecos/src/pecos/typing.py index 6ac4e47fd..022297e17 100644 --- a/python/quantum-pecos/src/pecos/typing.py +++ b/python/quantum-pecos/src/pecos/typing.py @@ -23,12 +23,143 @@ from __future__ import annotations -from typing import TYPE_CHECKING, Generic, Protocol, TypeAlias, TypedDict, TypeVar +from typing import TYPE_CHECKING, Generic, Literal, Protocol, TypeAlias, TypedDict, TypeVar import pecos_rslib as prs +from phir.model import ( + Barrier as _Barrier, +) +from phir.model import ( + Comment as _Comment, +) +from phir.model import ( + COp as _COp, +) +from phir.model import ( + CVarDefine as _CVarDefine, +) +from phir.model import ( + ExportVar as _ExportVar, +) +from phir.model import ( + FFCall as _FFCall, +) +from phir.model import ( + IfBlock as _IfBlock, +) +from phir.model import ( + MOpType as _MOpType, +) +from phir.model import ( + Op as _Op, +) +from phir.model import ( + PHIRModel as _PHIRModel, +) +from phir.model import ( + QOp as _QOp, +) +from phir.model import ( + QParBlock as _QParBlock, +) +from phir.model import ( + QVarDefine as _QVarDefine, +) +from phir.model import ( + SeqBlock as _SeqBlock, +) +from pydantic import model_validator + + +class _PecosCVarDefine(_CVarDefine): + """CVarDefine extended with 8-bit and 16-bit integer data types. + + The upstream PHIR spec's ``CVarDefine`` only accepts ``i32``, ``i64``, + ``u32``, ``u64``. PECOS additionally supports ``i8``, ``u8``, ``i16``, + ``u16`` for classical registers. The parent class's ``check_size`` + validator covers 32 and 64-bit cases; this subclass adds the matching + check for 8-bit and 16-bit sizes. + """ + + data_type: Literal["i8", "i16", "i32", "i64", "u8", "u16", "u32", "u64"] # type: ignore[assignment] + + @model_validator(mode="after") + def _check_size_small(self) -> _PecosCVarDefine: + """Check that ``size`` fits within 8-bit and 16-bit data types.""" + msg = "`size` is greater than what `data_type` can handle" + if self.size: + match self.data_type: + case "i8" | "u8": + if self.size > 8: + raise ValueError(msg) + case "i16" | "u16": + if self.size > 16: + raise ValueError(msg) + return self + + +_PecosDataMgmt: TypeAlias = _PecosCVarDefine | _QVarDefine | _ExportVar + + +class ResultCOp(_Op): + """PECOS-specific ``Result`` classical operation. + + Copies the value of internal classical registers to external result + variables, creating the destination variable if needed. Used by the + PECOS ``HybridEngine`` to transmit measurement bits between the inner + and outer classical interpreters. + + Example: + ``{"cop": "Result", "args": ["m"], "returns": ["c"]}`` + + This operation is a PECOS extension, not part of the upstream PHIR + specification. + """ + + cop: Literal["Result"] + args: list[str] + returns: list[str] + + +_PecosOpType: TypeAlias = _FFCall | _COp | ResultCOp | _QOp | _MOpType | _Barrier + + +class _PecosSeqBlock(_SeqBlock): + """SeqBlock extended with PECOS-specific classical operations.""" + + ops: list[_PecosOpType | _PecosBlockType] # type: ignore[assignment] + + +class _PecosIfBlock(_IfBlock): + """IfBlock extended with PECOS-specific classical operations.""" + + true_branch: list[_PecosOpType | _PecosBlockType] # type: ignore[assignment] + false_branch: list[_PecosOpType | _PecosBlockType] | None = None # type: ignore[assignment] + + +_PecosBlockType: TypeAlias = _PecosSeqBlock | _QParBlock | _PecosIfBlock +_PecosCmd: TypeAlias = _PecosDataMgmt | _PecosOpType | _PecosBlockType | _Comment + + +class PhirModel(_PHIRModel): + """PHIR model extended with PECOS-specific classical operations. + + Adds support for the ``Result`` cop used by PECOS ``HybridEngine`` to + map internal measurement registers to external result variables. Fully + backwards-compatible with upstream PHIR programs. + + The upstream ``phir.model.PHIRModel`` rejects programs containing + ``Result`` cops because ``Result`` is not in the PHIR specification. + Use this class (or ``pecos.typing.PhirModel``) when validating + programs that may contain PECOS extensions. + """ + + ops: list[_PecosCmd] # type: ignore[assignment] + -# Import external PHIR model with consistent naming -from phir.model import PHIRModel as PhirModel +_PecosSeqBlock.model_rebuild() +_PecosIfBlock.model_rebuild() +PhirModel.model_rebuild() # Type variable for dtype (used with Array[DType]) DType = TypeVar("DType") @@ -139,7 +270,7 @@ class ErrorParams(TypedDict, total=False): p2: float p2_mem: float | None p_meas: float | tuple[float, ...] - p_init: float + p_prep: float scale: float noiseless_qubits: set[int] diff --git a/python/quantum-pecos/tests/conftest.py b/python/quantum-pecos/tests/conftest.py index 07d166b8c..ecfcd5563 100644 --- a/python/quantum-pecos/tests/conftest.py +++ b/python/quantum-pecos/tests/conftest.py @@ -11,6 +11,8 @@ """Test configuration and shared fixtures.""" +import pytest + # Configure matplotlib to use non-interactive backend for tests (if available) # This must be done before importing matplotlib.pyplot to avoid GUI backend issues on Windows try: @@ -23,3 +25,14 @@ # Note: llvmlite functionality is now always available via Rust (pecos_rslib.ir and pecos_rslib.binding) # No need for conditional test skipping + + +def pytest_configure(config: pytest.Config) -> None: + """Register test-tree-local markers used by direct pytest invocations.""" + config.addinivalue_line( + "markers", + ( + "slow: mark tests that provide extra integration coverage but are " + "excluded from the default fast Python test lane" + ), + ) diff --git a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock index 89be9fe43..91c9344e4 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock +++ b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock @@ -2693,7 +2693,7 @@ dependencies = [ "num-complex", "num-traits", "pecos-random", - "rand 0.10.0", + "rand 0.10.1", "rand_core 0.10.0", "serde", "smallvec", @@ -2753,7 +2753,7 @@ dependencies = [ "pecos-core", "pecos-random", "pecos-simulators", - "rand 0.10.0", + "rand 0.10.1", "rayon", "serde", "serde_json", @@ -2822,7 +2822,7 @@ dependencies = [ "pecos-quantum", "pecos-random", "pecos-simulators", - "rand 0.10.0", + "rand 0.10.1", "rand_core 0.10.0", "rayon", "smallvec", @@ -2840,7 +2840,7 @@ dependencies = [ "num-complex", "num-traits", "pecos-random", - "rand 0.10.0", + "rand 0.10.1", "rustworkx-core", "serde", "serde_json", @@ -2911,7 +2911,7 @@ dependencies = [ "pecos-quantum", "pecos-random", "pecos-simulators", - "rand 0.10.0", + "rand 0.10.1", "rand_core 0.10.0", "rayon", "smallvec", @@ -2938,9 +2938,10 @@ dependencies = [ "pecos-qis-ffi", "pecos-qis-ffi-types", "pecos-random", - "rand 0.10.0", + "rand 0.10.1", "selene-simple-runtime", "selene-soft-rz-runtime", + "serde", "serde_json", "tempfile", ] @@ -2979,7 +2980,7 @@ dependencies = [ name = "pecos-random" version = "0.2.0-dev.0" dependencies = [ - "rand 0.10.0", + "rand 0.10.1", "rand_core 0.10.0", "rapidhash", "wide 1.2.0", @@ -2993,7 +2994,7 @@ dependencies = [ "pecos-core", "pecos-quantum", "pecos-random", - "rand 0.10.0", + "rand 0.10.1", "smallvec", "wide 1.2.0", ] @@ -3286,7 +3287,7 @@ dependencies = [ "bytes", "getrandom 0.3.4", "lru-slab", - "rand 0.9.2", + "rand 0.9.3", "ring", "rustc-hash", "rustls", @@ -3351,9 +3352,9 @@ dependencies = [ [[package]] name = "rand" -version = "0.9.2" +version = "0.9.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "6db2770f06117d490610c7488547d543617b21bfa07796d7a12f6f1bd53850d1" +checksum = "7ec095654a25171c2124e9e3393a930bddbffdc939556c914957a4c3e0a87166" dependencies = [ "rand_chacha", "rand_core 0.9.5", @@ -3361,9 +3362,9 @@ dependencies = [ [[package]] name = "rand" -version = "0.10.0" +version = "0.10.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "bc266eb313df6c5c09c1c7b1fbe2510961e5bcd3add930c1e31f7ed9da0feff8" +checksum = "d2e8e8bcc7961af1fdac401278c6a831614941f6164ee3bf4ce61b7edb162207" dependencies = [ "chacha20", "getrandom 0.4.2", @@ -3411,7 +3412,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "6a8615d50dcf34fa31f7ab52692afec947c4dd0ab803cc87cb3b0b4570ff7463" dependencies = [ "num-traits", - "rand 0.9.2", + "rand 0.9.3", ] [[package]] @@ -3801,7 +3802,7 @@ dependencies = [ "num-traits", "petgraph 0.8.3", "priority-queue", - "rand 0.9.2", + "rand 0.9.3", "rand_distr", "rand_pcg", "rayon", @@ -4299,7 +4300,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "32497e9a4c7b38532efcdebeef879707aa9f794296a4f0244f6f69e9bc8574bd" dependencies = [ "fastrand", - "getrandom 0.4.2", + "getrandom 0.3.4", "once_cell", "rustix", "windows-sys 0.52.0", diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/README.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/README.rs deleted file mode 100644 index 52d92624e..000000000 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/README.rs +++ /dev/null @@ -1,26 +0,0 @@ -//! Auto-generated Rust tests from README.md -//! DO NOT EDIT - Generated by scripts/docs/generate_doc_tests.py -#![allow(unused_imports, unused_variables, unused_mut, unused_assignments, dead_code, non_snake_case)] - - -#[test] -fn test_README_rust_1() -> Result<(), Box> { - use pecos::prelude::*; - // Define a Bell state circuit - let circuit = Qasm::from_string(r#" - OPENQASM 2.0; - include "qelib1.inc"; - qreg q[2]; - creg c[2]; - h q[0]; - cx q[0], q[1]; - measure q -> c; - "#); - - // Run 10 shots - let results = sim(circuit).seed(42).run(10)?; - println!("{:?}", results); - // 0 = both |0⟩, 3 = both |1⟩ (always correlated!) - Ok(()) -} - diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/development_foreign_plugins.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/development_foreign_plugins.rs new file mode 100644 index 000000000..a49fafce5 --- /dev/null +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/development_foreign_plugins.rs @@ -0,0 +1,27 @@ +//! Auto-generated Rust tests from development/foreign-plugins.md +//! DO NOT EDIT - Generated by scripts/docs/generate_doc_tests.py +#![allow(unused_imports, unused_variables, unused_mut, unused_assignments, dead_code, non_snake_case)] + + +#[test] +fn test_development_foreign_plugins_rust_3() { + use pecos_foreign::discovery::discover_plugins; + let plugins = discover_plugins(); // scans ~/.pecos/plugins/ + for plugin in &plugins { + println!("Loaded: {} (decoder: {}, simulator: {})", + plugin.name, plugin.decoder.is_some(), plugin.simulator.is_some()); + } +} + + + +#[test] +fn test_development_foreign_plugins_rust_4() -> Result<(), Box> { + use pecos_foreign::gate_support::configure_runner_for_foreign; + let sim = ForeignSimulator::new(handle, vtable); + let mut runner = configure_runner_for_foreign(&sim); + // If sim supports rotations: runner uses RX, RZ, RZZ natively + // Otherwise: Clifford-only, everything decomposes into {SZ, H, CX} + let outcomes = runner.apply_circuit(&mut sim, &commands)?; + Ok(()) +} diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_circuit_representation.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_circuit_representation.rs index 050209522..f86b85c0c 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_circuit_representation.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_circuit_representation.rs @@ -76,8 +76,9 @@ circuit.h(&[0]).meta("error_rate", Attribute::Float(0.001)); // Multiple metadata entries circuit.cx(&[(0, 1)]).meta("duration_ns", Attribute::Int(50)); -// Measurements break the chain but still support metadata -circuit.mz(&[0]).meta("basis", Attribute::String("Z".into())); +// Measurements return refs (not &mut Self), so chain separately +circuit.mz(&[0]); +circuit.meta("basis", Attribute::String("Z".into())); } diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_tolerance.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_tolerance.rs index 442214c2f..814cc31d6 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_tolerance.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_tolerance.rs @@ -189,7 +189,7 @@ fn test_user_guide_fault_tolerance_rust_8() -> Result<(), Box None: "p1": 2e-1, "p2": 2e-1, "p_meas": 2e-1, - "p_init": 1e-1, + "p_prep": 1e-1, "p1_error_model": { "X": 0.25, "Y": 0.25, diff --git a/python/quantum-pecos/tests/pecos/integration/test_backend_seed_determinism.py b/python/quantum-pecos/tests/pecos/integration/test_backend_seed_determinism.py index 0c1a2f5ec..7cb51baf2 100644 --- a/python/quantum-pecos/tests/pecos/integration/test_backend_seed_determinism.py +++ b/python/quantum-pecos/tests/pecos/integration/test_backend_seed_determinism.py @@ -108,7 +108,7 @@ "p1": 2e-1, "p2": 2e-1, "p_meas": 2e-1, - "p_init": 1e-1, + "p_prep": 1e-1, "p1_error_model": { "X": 0.25, "Y": 0.25, diff --git a/python/quantum-pecos/tests/pecos/integration/test_hybrid_engine_old_error_model.py b/python/quantum-pecos/tests/pecos/integration/test_hybrid_engine_old_error_model.py index 942f5afc7..aa91761fb 100644 --- a/python/quantum-pecos/tests/pecos/integration/test_hybrid_engine_old_error_model.py +++ b/python/quantum-pecos/tests/pecos/integration/test_hybrid_engine_old_error_model.py @@ -18,7 +18,7 @@ def test_simple_conditional() -> None: error_params = { "p1": 0.01, "p2": 0.01, - "p_init": 0.01, + "p_prep": 0.01, "p_meas": 0.01, "p2_mem": 0.01, } diff --git a/python/quantum-pecos/tests/pecos/integration/test_phir.py b/python/quantum-pecos/tests/pecos/integration/test_phir.py index a3e21fb61..467872450 100644 --- a/python/quantum-pecos/tests/pecos/integration/test_phir.py +++ b/python/quantum-pecos/tests/pecos/integration/test_phir.py @@ -16,9 +16,6 @@ import pytest from pecos import WasmForeignObject -from pecos.classical_interpreters.phir_classical_interpreter import ( - PhirClassicalInterpreter, -) from pecos.engines.hybrid_engine import HybridEngine from pecos.noise.generic_error_model import GenericErrorModel from phir.model import PHIRModel @@ -60,7 +57,7 @@ def test_spec_example_noisy_wasmtime() -> None: "p1": 2e-1, "p2": 2e-1, "p_meas": 2e-1, - "p_init": 1e-1, + "p_prep": 1e-1, "p1_error_model": { "X": 0.25, "Y": 0.25, @@ -95,7 +92,7 @@ def test_example1_noisy_wasmtime() -> None: "p1": 2e-1, "p2": 2e-1, "p_meas": 2e-1, - "p_init": 1e-1, + "p_prep": 1e-1, "p1_error_model": { "X": 0.25, "Y": 0.25, @@ -129,7 +126,7 @@ def test_example1_no_wasm_noisy() -> None: "p1": 2e-1, "p2": 2e-1, "p_meas": 2e-1, - "p_init": 1e-1, + "p_prep": 1e-1, "p1_error_model": { "X": 0.25, "Y": 0.25, @@ -211,11 +208,7 @@ def test_bell_qparallel_cliff() -> None: Tests that a program creating and measuring a Bell state using qparallel blocks returns expected results with Clifford circuits and stabilizer simulator. """ - # Create an interpreter with validation disabled for testing Result instruction - interp = PhirClassicalInterpreter() - interp.phir_validate = False - - results = HybridEngine(qsim="stabilizer", cinterp=interp).run( + results = HybridEngine(qsim="stabilizer").run( program=json.load( Path.open(this_dir / "phir" / "bell_qparallel_cliff.phir.json"), ), @@ -235,10 +228,7 @@ def test_bell_qparallel_cliff_barrier() -> None: Tests that a program creating and measuring a Bell state using qparallel blocks and barriers returns expected results with Clifford circuits and stabilizer simulator. """ - interp = PhirClassicalInterpreter() - interp.phir_validate = False - - results = HybridEngine(qsim="stabilizer", cinterp=interp).run( + results = HybridEngine(qsim="stabilizer").run( program=json.load( Path.open(this_dir / "phir" / "bell_qparallel_cliff_barrier.phir.json"), ), @@ -258,10 +248,7 @@ def test_bell_qparallel_cliff_ifbarrier() -> None: Tests that a program creating and measuring a Bell state using qparallel blocks and conditional barriers returns expected results with Clifford circuits and stabilizer simulator. """ - interp = PhirClassicalInterpreter() - interp.phir_validate = False - - results = HybridEngine(qsim="stabilizer", cinterp=interp).run( + results = HybridEngine(qsim="stabilizer").run( program=json.load( Path.open(this_dir / "phir" / "bell_qparallel_cliff_ifbarrier.phir.json"), ), diff --git a/python/quantum-pecos/tests/pecos/integration/test_phir_dep.py b/python/quantum-pecos/tests/pecos/integration/test_phir_dep.py index 5ed34b167..f6412b1ed 100644 --- a/python/quantum-pecos/tests/pecos/integration/test_phir_dep.py +++ b/python/quantum-pecos/tests/pecos/integration/test_phir_dep.py @@ -14,6 +14,7 @@ import json from pathlib import Path +import pytest from pecos.typing import PhirModel this_dir = Path(__file__).parent @@ -25,3 +26,97 @@ def test_spec_example() -> None: data = json.load(Path.open(this_dir / "phir/spec_example.phir.json")) PhirModel.model_validate(data) + + +def test_pecos_result_cop_top_level() -> None: + """PECOS Result cop validates at the top level of a PHIR program. + + The upstream ``phir.model.PHIRModel`` rejects Result because it is a + PECOS extension, not part of the spec. ``pecos.typing.PhirModel`` + subclasses the upstream model to add Result support. + """ + data = { + "format": "PHIR/JSON", + "version": "0.1.0", + "ops": [ + {"data": "cvar_define", "data_type": "u32", "variable": "m", "size": 1}, + {"data": "cvar_define", "data_type": "u32", "variable": "c", "size": 1}, + {"cop": "Result", "args": ["m"], "returns": ["c"]}, + ], + } + + PhirModel.model_validate(data) + + +def test_pecos_result_cop_inside_seqblock() -> None: + """Result cop validates when nested inside a SeqBlock.""" + data = { + "format": "PHIR/JSON", + "version": "0.1.0", + "ops": [ + {"data": "cvar_define", "data_type": "u32", "variable": "m", "size": 1}, + {"data": "cvar_define", "data_type": "u32", "variable": "c", "size": 1}, + { + "block": "sequence", + "ops": [{"cop": "Result", "args": ["m"], "returns": ["c"]}], + }, + ], + } + + PhirModel.model_validate(data) + + +@pytest.mark.parametrize( + ("dtype", "size"), + [ + ("i8", 8), + ("u8", 8), + ("i16", 16), + ("u16", 16), + ("i32", 32), + ("u32", 32), + ("i64", 64), + ("u64", 64), + ], +) +def test_pecos_cvar_define_small_dtypes(dtype: str, size: int) -> None: + """PECOS extends CVarDefine to support 8-bit and 16-bit integer dtypes. + + The upstream ``phir.model.CVarDefine`` only permits ``i32``, ``i64``, + ``u32``, ``u64``. PECOS programs use 8/16-bit dtypes too. + """ + data = { + "format": "PHIR/JSON", + "version": "0.1.0", + "ops": [{"data": "cvar_define", "data_type": dtype, "variable": "v", "size": size}], + } + + PhirModel.model_validate(data) + + +def test_cvar_define_size_exceeding_dtype_rejected() -> None: + """Extension remains strict: size must fit in the declared dtype.""" + from pydantic import ValidationError + + for dtype, bad_size in [("i8", 16), ("u8", 9), ("i16", 32), ("u16", 17)]: + data = { + "format": "PHIR/JSON", + "version": "0.1.0", + "ops": [{"data": "cvar_define", "data_type": dtype, "variable": "v", "size": bad_size}], + } + with pytest.raises(ValidationError): + PhirModel.model_validate(data) + + +def test_malformed_result_cop_still_rejected() -> None: + """Extension remains strict: Result cop missing required fields is rejected.""" + from pydantic import ValidationError + + data = { + "format": "PHIR/JSON", + "version": "0.1.0", + "ops": [{"cop": "Result"}], # missing args and returns + } + + with pytest.raises(ValidationError): + PhirModel.model_validate(data) diff --git a/python/quantum-pecos/tests/pecos/slr/ast/__init__.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/__init__.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/__init__.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/__init__.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/analysis/__init__.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/__init__.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/analysis/__init__.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/__init__.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/analysis/test_connectivity_analyzer.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/test_connectivity_analyzer.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/analysis/test_connectivity_analyzer.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/test_connectivity_analyzer.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/analysis/test_depth_analyzer.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/test_depth_analyzer.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/analysis/test_depth_analyzer.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/test_depth_analyzer.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/analysis/test_parallelism_analyzer.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/test_parallelism_analyzer.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/analysis/test_parallelism_analyzer.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/test_parallelism_analyzer.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/analysis/test_qubit_state_validator.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/test_qubit_state_validator.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/analysis/test_qubit_state_validator.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/test_qubit_state_validator.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/analysis/test_resource_counter.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/test_resource_counter.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/analysis/test_resource_counter.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/test_resource_counter.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/analysis/test_t_count_analyzer.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/test_t_count_analyzer.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/analysis/test_t_count_analyzer.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/analysis/test_t_count_analyzer.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/optimizations/__init__.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/optimizations/__init__.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/optimizations/__init__.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/optimizations/__init__.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/optimizations/test_gate_cancellation.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/optimizations/test_gate_cancellation.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/optimizations/test_gate_cancellation.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/optimizations/test_gate_cancellation.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/optimizations/test_identity_removal.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/optimizations/test_identity_removal.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/optimizations/test_identity_removal.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/optimizations/test_identity_removal.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/optimizations/test_inverse_cancellation.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/optimizations/test_inverse_cancellation.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/optimizations/test_inverse_cancellation.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/optimizations/test_inverse_cancellation.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/optimizations/test_pipeline.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/optimizations/test_pipeline.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/optimizations/test_pipeline.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/optimizations/test_pipeline.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/optimizations/test_rotation_merging.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/optimizations/test_rotation_merging.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/optimizations/test_rotation_merging.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/optimizations/test_rotation_merging.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_codegen_guppy.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_codegen_guppy.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_codegen_guppy.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_codegen_guppy.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_codegen_qasm.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_codegen_qasm.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_codegen_qasm.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_codegen_qasm.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_codegen_qir.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_codegen_qir.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_codegen_qir.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_codegen_qir.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_codegen_quantum_circuit.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_codegen_quantum_circuit.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_codegen_quantum_circuit.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_codegen_quantum_circuit.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_codegen_stim.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_codegen_stim.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_codegen_stim.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_codegen_stim.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_compare.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_compare.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_compare.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_compare.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_converter.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_converter.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_converter.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_converter.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_integration.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_integration.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_integration.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_integration.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_nodes.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_nodes.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_nodes.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_nodes.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_permute.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_permute.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_permute.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_permute.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_pretty_print.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_pretty_print.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_pretty_print.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_pretty_print.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_roundtrip.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_roundtrip.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_roundtrip.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_roundtrip.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_serialize.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_serialize.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_serialize.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_serialize.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_ast_visitor.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_visitor.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_ast_visitor.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_ast_visitor.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_codegen_equivalence.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_codegen_equivalence.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_codegen_equivalence.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_codegen_equivalence.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_compare.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_compare.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_compare.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_compare.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_integration.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_integration.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_integration.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_integration.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_pretty_print.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_pretty_print.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_pretty_print.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_pretty_print.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/test_serialize.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/test_serialize.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/test_serialize.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/test_serialize.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/validation/__init__.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/validation/__init__.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/validation/__init__.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/validation/__init__.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/validation/test_allocation_validator.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/validation/test_allocation_validator.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/validation/test_allocation_validator.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/validation/test_allocation_validator.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/validation/test_bounds_checker.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/validation/test_bounds_checker.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/validation/test_bounds_checker.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/validation/test_bounds_checker.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/validation/test_pipeline.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/validation/test_pipeline.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/validation/test_pipeline.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/validation/test_pipeline.py diff --git a/python/quantum-pecos/tests/pecos/slr/ast/validation/test_type_checker.py b/python/quantum-pecos/tests/pecos/slr/ast_tests/validation/test_type_checker.py similarity index 100% rename from python/quantum-pecos/tests/pecos/slr/ast/validation/test_type_checker.py rename to python/quantum-pecos/tests/pecos/slr/ast_tests/validation/test_type_checker.py diff --git a/python/quantum-pecos/tests/pecos/test_selene_interface_integration.py b/python/quantum-pecos/tests/pecos/test_selene_interface_integration.py index 9693ff843..bb555b916 100644 --- a/python/quantum-pecos/tests/pecos/test_selene_interface_integration.py +++ b/python/quantum-pecos/tests/pecos/test_selene_interface_integration.py @@ -120,3 +120,63 @@ def test_runtime_library_finding() -> None: # If we found loadable libraries, that's good enough for this diagnostic assert len(loadable_libraries) > 0, f"Found {len(loadable_libraries)} loadable Selene runtime libraries" + + +def test_selene_engine_python_exports() -> None: + """Test that the Selene engine convenience exports exist and are usable.""" + import pecos + import pecos_rslib + + assert hasattr(pecos_rslib, "selene_engine") + assert hasattr(pecos, "selene_engine") + + builder = pecos.selene_engine() + assert isinstance(builder, pecos.QisEngineBuilder) + + named_builder = pecos.qis_engine().selene_runtime("selene_simple_runtime") + assert isinstance(named_builder, pecos.QisEngineBuilder) + + +def test_sim_guppy_can_use_selene_engine_via_qis_path() -> None: + """Test that sim(Guppy(...)).classical(selene_engine()) routes HUGR through the QIS path.""" + import pecos + from guppylang import guppy + from guppylang.std.quantum import h, measure, qubit + + selene = pecos.selene_engine() + + @guppy + def coin() -> bool: + q = qubit() + h(q) + return measure(q) + + results = pecos.sim(pecos.Guppy(coin)).classical(selene).qubits(1).seed(42).run(10).to_dict() + assert len(results["measurement_0"]) == 10 + + +def test_sim_guppy_reuses_physical_slot_after_measurement() -> None: + """Test that a recycled physical slot is reinitialized when Guppy reallocates a qubit.""" + import pecos + from guppylang import guppy + from guppylang.std.quantum import measure, qubit, x + + selene = pecos.selene_engine() + + @guppy + def allocate_measure_allocate_again() -> tuple[bool, bool]: + q0 = qubit() + x(q0) + m0 = measure(q0) + q1 = qubit() + m1 = measure(q1) + return m0, m1 + + results = ( + pecos.sim(pecos.Guppy(allocate_measure_allocate_again)).classical(selene).qubits(1).seed(7).run(10).to_dict() + ) + + assert len(results["measurement_0"]) == 10 + assert len(results["measurement_1"]) == 10 + assert all(results["measurement_0"]) + assert not any(results["measurement_1"]) diff --git a/python/quantum-pecos/tests/pecos/test_selene_plugin_workspace.py b/python/quantum-pecos/tests/pecos/test_selene_plugin_workspace.py new file mode 100644 index 000000000..822518776 --- /dev/null +++ b/python/quantum-pecos/tests/pecos/test_selene_plugin_workspace.py @@ -0,0 +1,74 @@ +"""Checks for Selene plugin workspace consistency.""" + +from __future__ import annotations + +from pathlib import Path + +try: + import tomllib +except ModuleNotFoundError: # pragma: no cover + import tomli as tomllib + + +def _repo_root() -> Path: + return Path(__file__).resolve().parents[4] + + +def _load_toml(path: Path) -> dict: + with path.open("rb") as handle: + return tomllib.load(handle) + + +def _nonempty_selene_plugin_dirs(repo_root: Path) -> tuple[list[str], list[str]]: + """Return real plugin dirs and stray non-empty dirs.""" + plugin_root = repo_root / "python" / "selene-plugins" + real_dirs: list[str] = [] + stray_dirs: list[str] = [] + + for path in sorted(plugin_root.glob("pecos-selene-*")): + if not path.is_dir(): + continue + children = list(path.iterdir()) + if not children: + continue + # Cargo.toml / pyproject.toml members use forward slashes on all platforms; + # normalize via as_posix() so the comparison does not fail on Windows. + rel = path.relative_to(repo_root).as_posix() + if (path / "Cargo.toml").is_file() and (path / "pyproject.toml").is_file(): + real_dirs.append(rel) + else: + stray_dirs.append(rel) + return real_dirs, stray_dirs + + +def test_selene_plugin_workspace_members_are_explicit_and_complete() -> None: + """Workspace manifests should enumerate exactly the real Selene plugin packages.""" + repo_root = _repo_root() + + cargo_toml = _load_toml(repo_root / "Cargo.toml") + pyproject_toml = _load_toml(repo_root / "pyproject.toml") + + cargo_members = cargo_toml["workspace"]["members"] + uv_members = pyproject_toml["tool"]["uv"]["workspace"]["members"] + + cargo_plugin_members = [member for member in cargo_members if member.startswith("python/selene-plugins/")] + uv_plugin_members = [member for member in uv_members if member.startswith("python/selene-plugins/")] + + assert all( + "*" not in member for member in cargo_plugin_members + ), "Cargo workspace should list Selene plugins explicitly instead of using a wildcard" + assert all( + "*" not in member for member in uv_plugin_members + ), "uv workspace should list Selene plugins explicitly instead of using a wildcard" + + actual_plugin_dirs, stray_dirs = _nonempty_selene_plugin_dirs(repo_root) + msg = f"Found non-empty pecos-selene-* directories that are not real plugin packages: {stray_dirs}" + assert stray_dirs == [], msg + assert cargo_plugin_members == actual_plugin_dirs, ( + "Cargo workspace Selene plugin members are out of sync with the actual plugin packages on disk: " + f"{cargo_plugin_members} vs {actual_plugin_dirs}" + ) + assert uv_plugin_members == actual_plugin_dirs, ( + "uv workspace Selene plugin members are out of sync with the actual plugin packages on disk: " + f"{uv_plugin_members} vs {actual_plugin_dirs}" + ) diff --git a/python/quantum-pecos/tests/pecos/test_selene_sim_parity.py b/python/quantum-pecos/tests/pecos/test_selene_sim_parity.py new file mode 100644 index 000000000..756384cd0 --- /dev/null +++ b/python/quantum-pecos/tests/pecos/test_selene_sim_parity.py @@ -0,0 +1,581 @@ +"""Parity checks between PECOS sim(...).classical(selene_engine()) and direct selene_sim. + +These tests are intentionally focused on small Guppy surface-memory programs so we can +quickly detect drift between the PECOS QIS/Helios integration path and direct Selene. + +For full surface-memory experiments, exact noiseless shot-by-shot raw-register parity is +not a valid target: the generated programs start from simple product states, so the +complementary stabilizer family is genuinely random in the first noiseless round and then +repeats after projection. The tests below therefore compare the deterministic pieces that +should match exactly and the qualitative round-to-round behavior that both backends should +share. +""" + +from __future__ import annotations + +import contextlib +import json +import os +import tempfile +from collections import Counter, defaultdict +from pathlib import Path + +import pytest +from guppylang import guppy +from guppylang.std.builtins import array, comptime, result +from guppylang.std.quantum import cx, h, measure, measure_array, qubit, x + + +@guppy +def tagged_bits_named_array() -> None: + """Tiny named-array program to isolate raw result parity issues.""" + q0 = qubit() + q1 = qubit() + q2 = qubit() + x(q0) + x(q2) + final = measure_array(array(q0, q1, q2)) + result("final", final) + + +def make_repeated_single_bit_results(num_rounds: int) -> object: + """Create a tiny program that records the same named result repeatedly.""" + + @guppy + def repeated_single_bit_results() -> None: + for _ in range(comptime(num_rounds)): + q = qubit() + bit = measure(q) + result("synx", array(bit)) + + return repeated_single_bit_results + + +def make_tiny_x_syndrome_memory(num_rounds: int) -> object: + """Create a tiny memory-style circuit with fresh ancilla allocation each round.""" + + @guppy + def tiny_x_syndrome_memory() -> None: + data = qubit() + h(data) + + for _ in range(comptime(num_rounds)): + anc = qubit() + h(anc) + cx(anc, data) + h(anc) + bit = measure(anc) + result("synx", array(bit)) + + h(data) + final = measure_array(array(data)) + result("final", final) + + return tiny_x_syndrome_memory + + +def make_tiny_x_syndrome_memory_raw(num_rounds: int) -> object: + """Create the same tiny circuit but without named outputs. + + This helps us distinguish "raw measured bits are wrong" from + "named result collection is wrong". + """ + + @guppy + def tiny_x_syndrome_memory_raw() -> None: + data = qubit() + h(data) + + for _ in range(comptime(num_rounds)): + anc = qubit() + h(anc) + cx(anc, data) + h(anc) + _ = measure(anc) + + h(data) + _ = measure(data) + + return tiny_x_syndrome_memory_raw + + +@guppy +def alloc_reuse_probe() -> None: + """Measure |1>, then allocate again and verify the fresh qubit is |0>.""" + q = qubit() + x(q) + b1 = measure(q) + result("m1", array(b1)) + + q2 = qubit() + b2 = measure(q2) + result("m2", array(b2)) + + +def _require_selene_runtime() -> object: + """Eagerly instantiate the Selene engine to fail fast if it is unavailable. + + The PECOS test environment is expected to have the Selene runtime + installed (see ``pecos setup``). A failure here means the environment is + broken, not that the test should be skipped. + """ + import pecos + + return pecos.selene_engine() + + +def _configure_selene_caches() -> None: + tmpdir = Path(tempfile.gettempdir()) + os.environ.setdefault("ZIG_GLOBAL_CACHE_DIR", str(tmpdir / "pecos_zig_global_cache")) + os.environ.setdefault("ZIG_LOCAL_CACHE_DIR", str(tmpdir / "pecos_zig_local_cache")) + + +def test_qis_trace_operations_write_chunks_on_run_path(tmp_path: Path) -> None: + """trace_operations() should work on the direct SimBuilder.run() QIS path too.""" + import pecos + + _require_selene_runtime() + + ( + pecos.sim(make_tiny_x_syndrome_memory(1)) + .classical(pecos.selene_engine()) + .quantum(pecos.stabilizer()) + .trace_operations(str(tmp_path)) + .qubits(2) + .seed(123) + .run(1) + ) + + trace_files = sorted(tmp_path.glob("*.json")) + assert trace_files + + payload = json.loads(trace_files[0].read_text()) + assert payload["format"] == "pecos_qis_operation_trace_v1" + assert payload["num_operations"] > 0 + assert payload["lowered_quantum_ops"] + + +def test_capture_operation_trace_returns_in_memory_batches() -> None: + """capture_operation_trace() should return the structured trace in memory.""" + import pecos + + _require_selene_runtime() + + trace = ( + pecos.sim(make_tiny_x_syndrome_memory(1)) + .classical(pecos.selene_engine()) + .quantum(pecos.stabilizer()) + .qubits(2) + .seed(123) + .capture_operation_trace() + ) + + assert isinstance(trace, list) + assert trace + assert trace[0]["format"] == "pecos_qis_operation_trace_v1" + assert trace[0]["num_operations"] > 0 + assert trace[0]["lowered_quantum_ops"] + + +def _collect_selene_named_results( + instance: object, + *, + n_qubits: int, + n_shots: int, + p: float, + seed: int, +) -> dict[str, list[int] | list[list[int]]]: + from selene_sim import DepolarizingErrorModel, SimpleRuntime, Stim + + results: dict[str, list[int] | list[list[int]]] = defaultdict(list) + try: + for shot_results in instance.run_shots( + simulator=Stim(), + n_qubits=n_qubits, + n_shots=n_shots, + error_model=DepolarizingErrorModel( + p_1q=p, + p_2q=p, + p_meas=p, + p_init=p, + ), + runtime=SimpleRuntime(), + random_seed=seed, + n_processes=1, + ): + shot_rows: dict[str, list[int]] = defaultdict(list) + for name, values in shot_results: + shot_rows[name].extend(int(v) for v in values) + for name, values in shot_rows.items(): + # Match ShotMap.to_dict(): one-bit registers become a flat list across + # shots, while vector-valued registers remain nested by shot. + if len(values) == 1: + results[name].append(values[0]) + else: + results[name].append(values) + finally: + delete_files = getattr(instance, "delete_files", None) + if callable(delete_files): + with contextlib.suppress(Exception): + delete_files() + + return dict(results) + + +def _collect_selene_named_results_with_custom_noise( + instance: object, + *, + n_qubits: int, + n_shots: int, + p1: float, + p2: float, + p_meas: float, + p_prep: float, + seed: int, +) -> dict[str, list[int] | list[list[int]]]: + from selene_sim import DepolarizingErrorModel, SimpleRuntime, Stim + + results: dict[str, list[int] | list[list[int]]] = defaultdict(list) + try: + for shot_results in instance.run_shots( + simulator=Stim(), + n_qubits=n_qubits, + n_shots=n_shots, + error_model=DepolarizingErrorModel( + p_1q=p1, + p_2q=p2, + p_meas=p_meas, + p_init=p_prep, + ), + runtime=SimpleRuntime(), + random_seed=seed, + n_processes=1, + ): + shot_rows: dict[str, list[int]] = defaultdict(list) + for name, values in shot_results: + shot_rows[name].extend(int(v) for v in values) + for name, values in shot_rows.items(): + if len(values) == 1: + results[name].append(values[0]) + else: + results[name].append(values) + finally: + delete_files = getattr(instance, "delete_files", None) + if callable(delete_files): + with contextlib.suppress(Exception): + delete_files() + + return dict(results) + + +def _counter_total_variation( + lhs: Counter[tuple[int, ...] | int], + rhs: Counter[tuple[int, ...] | int], + *, + total_count: int, +) -> float: + all_keys = set(lhs) | set(rhs) + return 0.5 * sum(abs(lhs[key] / total_count - rhs[key] / total_count) for key in all_keys) + + +def _round_blocks_repeat(row: list[int], num_rounds: int) -> bool: + if len(row) % num_rounds != 0: + return False + block_size = len(row) // num_rounds + blocks = [tuple(row[round_idx * block_size : (round_idx + 1) * block_size]) for round_idx in range(num_rounds)] + return all(block == blocks[0] for block in blocks[1:]) + + +def _run_surface_memory_via_sim( + *, + distance: int, + num_rounds: int, + basis: str, + shots: int, + p: float, + seed: int, +) -> dict[str, list[list[int]]]: + import pecos + from pecos.guppy import get_num_qubits, make_surface_code + + _require_selene_runtime() + + program = make_surface_code(distance=distance, num_rounds=num_rounds, basis=basis) + noise_model = pecos.depolarizing_noise().with_uniform_probability(p) + return ( + pecos.sim(program) + .classical(pecos.selene_engine()) + .quantum(pecos.stabilizer()) + .qubits(get_num_qubits(distance)) + .noise(noise_model) + .seed(seed) + .run(shots) + .to_shot_map() + .to_dict() + ) + + +def _run_surface_memory_via_selene_sim( + *, + distance: int, + num_rounds: int, + basis: str, + shots: int, + p: float, + seed: int, +) -> dict[str, list[int] | list[list[int]]]: + from pecos.compilation_pipeline import compile_guppy_to_hugr + from pecos.guppy import get_num_qubits, make_surface_code + from selene_sim import build + + _configure_selene_caches() + + program = make_surface_code(distance=distance, num_rounds=num_rounds, basis=basis) + hugr_bytes = compile_guppy_to_hugr(program) + instance = build(hugr_bytes, name=f"surface_d{distance}_{basis.lower()}_r{num_rounds}") + + return _collect_selene_named_results( + instance, + n_qubits=get_num_qubits(distance), + n_shots=shots, + p=p, + seed=seed, + ) + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_surface_memory_selene_backends_return_same_register_shapes(basis: str) -> None: + """Both gate-level Selene-backed entry points should at least agree on output shape.""" + sim_results = _run_surface_memory_via_sim( + distance=3, + num_rounds=2, + basis=basis, + shots=2, + p=0.0, + seed=123, + ) + selene_results = _run_surface_memory_via_selene_sim( + distance=3, + num_rounds=2, + basis=basis, + shots=2, + p=0.0, + seed=123, + ) + + assert set(sim_results) == {"final", "synx", "synz"} + assert set(selene_results) == {"final", "synx", "synz"} + + for key in ("final", "synx", "synz"): + assert len(sim_results[key]) == 2 + assert len(selene_results[key]) == 2 + assert len(sim_results[key][0]) == len(selene_results[key][0]) + + +def test_named_bool_array_matches_between_selene_backends() -> None: + """A simple named bool-array program should agree exactly across gate backends.""" + import pecos + from pecos.compilation_pipeline import compile_guppy_to_hugr + from selene_sim import build + + _require_selene_runtime() + _configure_selene_caches() + + sim_results = ( + pecos.sim(pecos.Guppy(tagged_bits_named_array)) + .classical(pecos.selene_engine()) + .quantum(pecos.stabilizer()) + .qubits(3) + .noise(pecos.depolarizing_noise().with_uniform_probability(0.0)) + .seed(123) + .run(1) + .to_shot_map() + .to_dict() + ) + + instance = build(compile_guppy_to_hugr(tagged_bits_named_array), name="tagged_bits_named_array") + selene_results = _collect_selene_named_results(instance, n_qubits=3, n_shots=1, p=0.0, seed=123) + + assert sim_results == selene_results == {"final": [[1, 0, 1]]} + + +def test_repeated_named_bool_array_matches_between_selene_backends() -> None: + """Repeated named outputs should accumulate identically across gate backends.""" + import pecos + from pecos.compilation_pipeline import compile_guppy_to_hugr + from selene_sim import build + + _require_selene_runtime() + _configure_selene_caches() + + program = make_repeated_single_bit_results(3) + + sim_results = ( + pecos.sim(pecos.Guppy(program)) + .classical(pecos.selene_engine()) + .quantum(pecos.stabilizer()) + .qubits(1) + .noise(pecos.depolarizing_noise().with_uniform_probability(0.0)) + .seed(123) + .run(1) + .to_shot_map() + .to_dict() + ) + + instance = build(compile_guppy_to_hugr(program), name="repeated_single_bit_results") + selene_results = _collect_selene_named_results(instance, n_qubits=1, n_shots=1, p=0.0, seed=123) + + assert sim_results == selene_results == {"synx": [[0, 0, 0]]} + + +def test_tiny_syndrome_memory_matches_between_selene_backends() -> None: + """A tiny syndrome-extraction pattern should match before we blame the full surface program.""" + import pecos + from pecos.compilation_pipeline import compile_guppy_to_hugr + from selene_sim import build + + _require_selene_runtime() + _configure_selene_caches() + + program = make_tiny_x_syndrome_memory(2) + + sim_results = ( + pecos.sim(pecos.Guppy(program)) + .classical(pecos.selene_engine()) + .quantum(pecos.stabilizer()) + .qubits(2) + .noise(pecos.depolarizing_noise().with_uniform_probability(0.0)) + .seed(123) + .run(1) + .to_shot_map() + .to_dict() + ) + + instance = build(compile_guppy_to_hugr(program), name="tiny_x_syndrome_memory") + selene_results = _collect_selene_named_results(instance, n_qubits=2, n_shots=1, p=0.0, seed=123) + + assert sim_results == selene_results + + +def test_tiny_syndrome_memory_p2_only_matches_between_selene_backends_statistically() -> None: + """The tiny CX-based syndrome probe should stay distributionally aligned under p2-only noise.""" + import pecos + from pecos.compilation_pipeline import compile_guppy_to_hugr + from selene_sim import build + + _require_selene_runtime() + _configure_selene_caches() + + shots = 5_000 + p2 = 0.01 + program = make_tiny_x_syndrome_memory(3) + + sim_results = ( + pecos.sim(pecos.Guppy(program)) + .classical(pecos.selene_engine()) + .quantum(pecos.stabilizer()) + .qubits(2) + .noise( + pecos.depolarizing_noise() + .with_p1_probability(0.0) + .with_p2_probability(p2) + .with_meas_probability(0.0) + .with_prep_probability(0.0), + ) + .seed(123) + .run(shots) + .to_shot_map() + .to_dict() + ) + + instance = build(compile_guppy_to_hugr(program), name="tiny_x_syndrome_memory_p2_only") + selene_results = _collect_selene_named_results_with_custom_noise( + instance, + n_qubits=2, + n_shots=shots, + p1=0.0, + p2=p2, + p_meas=0.0, + p_prep=0.0, + seed=123, + ) + + sim_synx = Counter(tuple(row) for row in sim_results["synx"]) + selene_synx = Counter(tuple(row) for row in selene_results["synx"]) + sim_final = Counter(sim_results["final"]) + selene_final = Counter(selene_results["final"]) + + assert _counter_total_variation(sim_synx, selene_synx, total_count=shots) < 0.01 + assert _counter_total_variation(sim_final, selene_final, total_count=shots) < 0.01 + + +def test_alloc_reuse_probe_matches_between_selene_backends() -> None: + """Fresh allocation after a `|1>` measurement should still return `|0>`.""" + import pecos + from pecos.compilation_pipeline import compile_guppy_to_hugr + from selene_sim import build + + _require_selene_runtime() + _configure_selene_caches() + + sim_results = ( + pecos.sim(pecos.Guppy(alloc_reuse_probe)) + .classical(pecos.selene_engine()) + .quantum(pecos.stabilizer()) + .qubits(1) + .noise(pecos.depolarizing_noise().with_uniform_probability(0.0)) + .seed(123) + .run(1) + .to_shot_map() + .to_dict() + ) + + instance = build(compile_guppy_to_hugr(alloc_reuse_probe), name="alloc_reuse_probe") + selene_results = _collect_selene_named_results(instance, n_qubits=1, n_shots=1, p=0.0, seed=123) + + assert sim_results == selene_results == {"m1": [1], "m2": [0]} + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_surface_memory_selene_backends_match_noiseless_deterministic_family(basis: str) -> None: + """The stabilizer family commuting with the prepared basis should stay all-zero.""" + sim_results = _run_surface_memory_via_sim( + distance=3, + num_rounds=6, + basis=basis, + shots=2, + p=0.0, + seed=123, + ) + selene_results = _run_surface_memory_via_selene_sim( + distance=3, + num_rounds=6, + basis=basis, + shots=2, + p=0.0, + seed=123, + ) + + det_key = "synx" if basis == "X" else "synz" + assert sim_results[det_key] == selene_results[det_key] + for row in sim_results[det_key]: + assert all(bit == 0 for bit in row) + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_surface_memory_noiseless_complementary_family_repeats_after_projection(basis: str) -> None: + """After the first noiseless round, repeated rounds should replay the same syndrome block.""" + num_rounds = 6 + comp_key = "synz" if basis == "X" else "synx" + + for runner in (_run_surface_memory_via_sim, _run_surface_memory_via_selene_sim): + results = runner( + distance=3, + num_rounds=num_rounds, + basis=basis, + shots=5, + p=0.0, + seed=123, + ) + for row in results[comp_key]: + assert _round_blocks_repeat(row, num_rounds) diff --git a/python/quantum-pecos/tests/pecos/unit/test_qasm_to_phir_json.py b/python/quantum-pecos/tests/pecos/unit/test_qasm_to_phir_json.py index 7cb11c255..d4a07dcea 100644 --- a/python/quantum-pecos/tests/pecos/unit/test_qasm_to_phir_json.py +++ b/python/quantum-pecos/tests/pecos/unit/test_qasm_to_phir_json.py @@ -157,11 +157,9 @@ def _run_phir_json(phir: dict, *, shots: int = 1, seed: int = 42) -> dict: from pecos_rslib import RustPhirClassicalInterpreter py_i = PhirClassicalInterpreter() - py_i.phir_validate = False py_r = HybridEngine(cinterp=py_i).run(phir, shots=shots, seed=seed, return_int=True) rs_i = RustPhirClassicalInterpreter() - rs_i.phir_validate = False rs_r = HybridEngine(cinterp=rs_i).run(phir, shots=shots, seed=seed, return_int=True) py_vals = {k: int(v[0]) for k, v in py_r.items()} diff --git a/python/quantum-pecos/tests/pecos/unit/test_rust_python_parity.py b/python/quantum-pecos/tests/pecos/unit/test_rust_python_parity.py index eb49bc872..d6671a8b5 100644 --- a/python/quantum-pecos/tests/pecos/unit/test_rust_python_parity.py +++ b/python/quantum-pecos/tests/pecos/unit/test_rust_python_parity.py @@ -46,7 +46,6 @@ def run_both( kw["qsim"] = qsim py_i = PhirClassicalInterpreter() - py_i.phir_validate = False py_r = HybridEngine(cinterp=py_i, **kw).run( phir, foreign_object=foreign_object, @@ -56,7 +55,6 @@ def run_both( ) rs_i = RustPhirClassicalInterpreter() - rs_i.phir_validate = False rs_r = HybridEngine(cinterp=rs_i, **kw).run( phir, foreign_object=foreign_object, @@ -106,7 +104,6 @@ def test_wasm_spec_example() -> None: math_wat = WAT_DIR / "math.wat" py_i = PhirClassicalInterpreter() - py_i.phir_validate = False py_r = HybridEngine(cinterp=py_i).run( phir, foreign_object=WasmForeignObject(math_wat), @@ -115,7 +112,6 @@ def test_wasm_spec_example() -> None: ) rs_i = RustPhirClassicalInterpreter() - rs_i.phir_validate = False rs_r = HybridEngine(cinterp=rs_i).run( phir, foreign_object=WasmForeignObject(math_wat), diff --git a/python/quantum-pecos/tests/pecos/unit/test_surface_sweep_math.py b/python/quantum-pecos/tests/pecos/unit/test_surface_sweep_math.py new file mode 100644 index 000000000..7f01a1e00 --- /dev/null +++ b/python/quantum-pecos/tests/pecos/unit/test_surface_sweep_math.py @@ -0,0 +1,731 @@ +# Copyright 2026 The PECOS Developers +# +# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with +# the License.You may obtain a copy of the License at +# +# https://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an +# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the +# specific language governing permissions and limitations under the License. + +"""Unit tests for the fit math in examples/surface/native_dem_threshold_sweep.py. + +These helpers are pure functions with no external dependencies, so they can be +tested directly without running a full sweep. The goal is to catch silent +numerical regressions in the stats path (Wilson intervals, golden-section fit, +linear regression, threshold-scaling gates) that would otherwise only show up +as bad numbers on a real sweep. +""" + +from __future__ import annotations + +import importlib.util +import json +import math +import sys +from pathlib import Path +from typing import TYPE_CHECKING + +import pytest + +if TYPE_CHECKING: + from types import ModuleType + + +def _repo_root() -> Path: + """Return the repo root directory by walking up from this test file.""" + cur = Path(__file__).resolve() + for candidate in [cur, *cur.parents]: + if (candidate / "Justfile").is_file() and (candidate / "examples").is_dir(): + return candidate + msg = f"Could not locate repo root above {cur}" + raise RuntimeError(msg) + + +_SWEEP_MODULE_NAME = "_surface_sweep_under_test" + + +def _load_sweep_module() -> ModuleType: + """Load the sweep example script as an importable module for white-box testing. + + The example lives outside any Python package, so we load it by path. The + module is registered in ``sys.modules`` before executing so that + ``dataclass()`` can resolve ``cls.__module__`` when introspecting string + annotations (otherwise ``dataclasses.py`` crashes on + ``sys.modules.get(cls.__module__).__dict__``). + """ + example_path = _repo_root() / "examples" / "surface" / "native_dem_threshold_sweep.py" + spec = importlib.util.spec_from_file_location(_SWEEP_MODULE_NAME, example_path) + if spec is None or spec.loader is None: + msg = f"Could not load sweep module from {example_path}" + raise RuntimeError(msg) + module = importlib.util.module_from_spec(spec) + sys.modules[_SWEEP_MODULE_NAME] = module + try: + spec.loader.exec_module(module) + except Exception: + sys.modules.pop(_SWEEP_MODULE_NAME, None) + raise + return module + + +@pytest.fixture(scope="module") +def sweep() -> ModuleType: + """Module-scoped handle to the loaded sweep example script.""" + return _load_sweep_module() + + +def _make_point( + sweep: ModuleType, + *, + distance: int, + basis: str, + p: float, + total_rounds: int, + logical_error_rate: float, + num_shots: int = 1000, +) -> object: + """Build a ``SweepPoint`` consistent with the given logical error rate.""" + num_errors = round(logical_error_rate * num_shots) + return sweep.SweepPoint( + backend="test", + distance=distance, + basis=basis, + physical_error_rate=p, + total_rounds=total_rounds, + num_shots=num_shots, + num_logical_errors=num_errors, + num_raw_errors=None, + logical_error_rate=logical_error_rate, + raw_error_rate=None, + ) + + +def _make_summary( + sweep: ModuleType, + *, + distance: int, + p: float, + epsilon_per_round: float, + basis: str = "X", + fit_rms: float = 0.0, +) -> object: + """Build a ``FitSummary`` with the given fitted per-round rate and RMS.""" + projected = sweep.ler_over_rounds(epsilon_per_round, distance) + return sweep.FitSummary( + backend="test", + distance=distance, + basis=basis, + physical_error_rate=p, + num_shots_per_round_point=1000, + round_values=(distance, distance + 1), + observed_logical_error_rates=(projected, projected), + observed_raw_error_rates=(None, None), + fitted_logical_error_rate_per_round=epsilon_per_round, + fitted_projected_logical_error_rate_over_d_rounds=projected, + fit_root_mean_square_error=fit_rms, + ) + + +# --------------------------------------------------------------------------- +# Wilson interval +# --------------------------------------------------------------------------- + + +def test_wilson_interval_zero_errors_is_nonzero_upper(sweep: ModuleType) -> None: + """With no observed errors the lower bound is zero but the upper is not.""" + low, high = sweep._wilson_interval(0, 100) + assert low == 0.0 + assert 0.0 < high < 1.0 + + +def test_wilson_interval_all_errors_is_nonzero_lower(sweep: ModuleType) -> None: + """With every trial an error the upper bound is one but the lower is not.""" + low, high = sweep._wilson_interval(100, 100) + assert high == 1.0 + assert 0.0 < low < 1.0 + + +def test_wilson_interval_brackets_point_estimate(sweep: ModuleType) -> None: + """The interval must contain the point estimate and lie inside ``[0, 1]``.""" + n = 1000 + k = 37 + low, high = sweep._wilson_interval(k, n) + point = k / n + assert low <= point <= high + assert 0.0 <= low < high <= 1.0 + + +def test_wilson_interval_rejects_zero_trials(sweep: ModuleType) -> None: + """Zero trials has no defined interval; must raise.""" + with pytest.raises(ValueError, match="num_trials must be positive"): + sweep._wilson_interval(0, 0) + + +# --------------------------------------------------------------------------- +# Linear regression +# --------------------------------------------------------------------------- + + +def test_linear_regression_exact_line(sweep: ModuleType) -> None: + """Regression of an exact line recovers (slope, intercept).""" + xs = [0.0, 1.0, 2.0, 3.0] + ys = [1.0, 3.0, 5.0, 7.0] # y = 2x + 1 + slope, intercept = sweep._linear_regression(xs, ys) + assert slope == pytest.approx(2.0) + assert intercept == pytest.approx(1.0) + + +def test_linear_regression_rejects_too_few_points(sweep: ModuleType) -> None: + """Fewer than two points is not a valid regression.""" + with pytest.raises(ValueError, match="at least two"): + sweep._linear_regression([1.0], [2.0]) + + +def test_linear_regression_rejects_degenerate_x(sweep: ModuleType) -> None: + """All-equal ``xs`` makes the slope undefined.""" + with pytest.raises(ValueError, match="distinct x"): + sweep._linear_regression([1.0, 1.0, 1.0], [2.0, 3.0, 4.0]) + + +def test_linear_regression_requires_matching_lengths(sweep: ModuleType) -> None: + """Mismatched ``xs``/``ys`` lengths is a programmer error.""" + with pytest.raises(ValueError, match="same length"): + sweep._linear_regression([1.0, 2.0], [3.0]) + + +# --------------------------------------------------------------------------- +# Per-round rate fit +# --------------------------------------------------------------------------- + + +def test_fit_per_round_rate_recovers_known_rate(sweep: ModuleType) -> None: + """Fitting points generated from a known per-round rate recovers that rate.""" + true_rate = 3.0e-3 + rounds = [6, 8, 10, 12] + points = [ + _make_point( + sweep, + distance=5, + basis="X", + p=0.005, + total_rounds=r, + logical_error_rate=sweep.ler_over_rounds(true_rate, r), + ) + for r in rounds + ] + fitted = sweep._fit_per_round_rate(points) + assert fitted == pytest.approx(true_rate, rel=1e-3) + + +def test_fit_per_round_rate_single_point_closed_form(sweep: ModuleType) -> None: + """With one observation the fit uses the closed-form per-round inversion.""" + true_rate = 2.5e-3 + r = 10 + points = [ + _make_point( + sweep, + distance=5, + basis="X", + p=0.005, + total_rounds=r, + logical_error_rate=sweep.ler_over_rounds(true_rate, r), + ), + ] + fitted = sweep._fit_per_round_rate(points) + assert fitted == pytest.approx(true_rate, rel=1e-6) + + +def test_fit_per_round_rate_empty_raises(sweep: ModuleType) -> None: + """Zero observations cannot be fit and must raise a clear error.""" + with pytest.raises(ValueError, match="at least one"): + sweep._fit_per_round_rate([]) + + +def test_fit_per_round_rate_all_zero_returns_zero(sweep: ModuleType) -> None: + """All-zero observed logical error rates imply a zero per-round rate.""" + points = [ + _make_point(sweep, distance=5, basis="X", p=0.005, total_rounds=r, logical_error_rate=0.0) for r in (6, 8, 10) + ] + assert sweep._fit_per_round_rate(points) == 0.0 + + +# --------------------------------------------------------------------------- +# Noise-dominated fit warning +# --------------------------------------------------------------------------- + + +def test_fit_rms_warning_emitted_when_rms_exceeds_epsilon(sweep: ModuleType) -> None: + """Warning fires when the fit residual dwarfs the fitted per-round rate.""" + summary = _make_summary(sweep, distance=3, p=0.006, epsilon_per_round=5.0e-3, fit_rms=1.0e-2) + text = sweep._fit_rms_warning_text(summary) + assert text # non-empty + assert "WARNING" in text + assert "increase --shots" in text + + +def test_fit_rms_warning_silent_when_rms_below_epsilon(sweep: ModuleType) -> None: + """A well-converged fit (RMS much smaller than epsilon) emits no warning.""" + summary = _make_summary(sweep, distance=5, p=0.002, epsilon_per_round=5.0e-3, fit_rms=1.0e-4) + assert sweep._fit_rms_warning_text(summary) == "" + + +def test_fit_rms_warning_silent_for_degenerate_epsilon(sweep: ModuleType) -> None: + """``eps==0`` and ``eps>=0.5`` are handled elsewhere and should not trigger a noise warning.""" + for eps in (0.0, 0.5): + summary = _make_summary(sweep, distance=3, p=0.1, epsilon_per_round=eps, fit_rms=1.0) + assert sweep._fit_rms_warning_text(summary) == "" + + +# --------------------------------------------------------------------------- +# Threshold-fit gating (no tautological p_th from two-point fits) +# --------------------------------------------------------------------------- + + +def test_fit_distance_scaling_none_with_two_distances(sweep: ModuleType) -> None: + """Two distances trivially fit a line; p_th would be tautological so skip.""" + summaries = [ + _make_summary(sweep, distance=3, p=0.006, epsilon_per_round=6.0e-3), + _make_summary(sweep, distance=5, p=0.006, epsilon_per_round=3.0e-3), + ] + assert sweep._fit_distance_scaling_at_fixed_p(summaries) is None + + +def test_fit_distance_scaling_ok_with_three_distances(sweep: ModuleType) -> None: + """With three distances the fixed-p scaling fit returns a meaningful threshold.""" + summaries = [ + _make_summary(sweep, distance=3, p=0.006, epsilon_per_round=6.0e-3), + _make_summary(sweep, distance=5, p=0.006, epsilon_per_round=3.0e-3), + _make_summary(sweep, distance=7, p=0.006, epsilon_per_round=1.5e-3), + ] + fit = sweep._fit_distance_scaling_at_fixed_p(summaries) + assert fit is not None + assert fit.fitted_suppression_factor == pytest.approx(math.exp(math.log(2.0))) + assert fit.fitted_threshold == pytest.approx(0.006 * 2.0) + + +def test_fit_global_scaling_none_with_two_points(sweep: ModuleType) -> None: + """Two (d, p) points fit two parameters perfectly; skip to avoid tautology.""" + summaries = [ + _make_summary(sweep, distance=3, p=0.006, epsilon_per_round=6.0e-3), + _make_summary(sweep, distance=5, p=0.006, epsilon_per_round=3.0e-3), + ] + assert sweep._fit_global_scaling_law(summaries) is None + + +def test_fit_global_scaling_ok_with_three_points(sweep: ModuleType) -> None: + """With three or more (d, p) points the global scaling fit runs.""" + summaries = [ + _make_summary(sweep, distance=3, p=0.006, epsilon_per_round=6.0e-3), + _make_summary(sweep, distance=5, p=0.006, epsilon_per_round=3.0e-3), + _make_summary(sweep, distance=7, p=0.006, epsilon_per_round=1.5e-3), + ] + fit = sweep._fit_global_scaling_law(summaries) + assert fit is not None + assert fit.fitted_threshold > 0.0 + + +# --------------------------------------------------------------------------- +# Dashboard rebuild ordering +# --------------------------------------------------------------------------- + + +def test_load_sweep_data_from_json_recovers_tuple_fields(sweep: ModuleType, tmp_path: Path) -> None: + """Round-tripping a FitSummary through JSON must restore tuple-typed fields as tuples.""" + import dataclasses + + summary = _make_summary(sweep, distance=5, p=0.005, epsilon_per_round=2.0e-3) + json_path = tmp_path / "results.json" + json_path.write_text(json.dumps({"points": [], "fit_summaries": [dataclasses.asdict(summary)]})) + + _, summaries, _ = sweep.load_sweep_data_from_json(json_path) + assert len(summaries) == 1 + loaded = summaries[0] + # Tuple fields would arrive as JSON arrays without explicit reconstruction; + # the loader must promote them back to tuples so downstream code that expects + # tuple semantics (hashing, equality) still works. + assert isinstance(loaded.round_values, tuple) + assert isinstance(loaded.observed_logical_error_rates, tuple) + assert loaded.fitted_logical_error_rate_per_round == pytest.approx(2.0e-3) + + +def test_render_plot_artifacts_from_loaded_json_produces_files( + sweep: ModuleType, + tmp_path: Path, +) -> None: + """JSON results file should be enough to regenerate plots without rerunning the sweep.""" + import dataclasses + + points = [ + sweep.SweepPoint( + backend="test", + distance=d, + basis="X", + physical_error_rate=0.005, + total_rounds=r, + num_shots=1000, + num_logical_errors=int(0.02 * 1000), + num_raw_errors=None, + logical_error_rate=0.02, + raw_error_rate=None, + ) + for d in (3, 5) + for r in (6, 8) + ] + summaries = [ + _make_summary(sweep, distance=d, p=0.005, epsilon_per_round=eps, basis="X") + for d, eps in [(3, 4.0e-3), (5, 2.0e-3)] + ] + + json_path = tmp_path / "myrun_results.json" + json_path.write_text( + json.dumps( + { + "points": [dataclasses.asdict(point) for point in points], + "fit_summaries": [dataclasses.asdict(summary) for summary in summaries], + }, + ), + ) + + loaded_points, loaded_summaries, _ = sweep.load_sweep_data_from_json(json_path) + plots = sweep.render_plot_artifacts( + tmp_path, + prefix="myrun", + points=loaded_points, + summaries=loaded_summaries, + formats=["svg", "pdf"], + ) + + assert plots, "render_plot_artifacts should return DashboardPlot entries for SVG outputs" + expected_files = { + "myrun_test_per_round_overlay.svg", + "myrun_test_per_round_overlay.pdf", + "myrun_test_p_0p005_duration_overlay.svg", + "myrun_test_p_0p005_duration_overlay.pdf", + "myrun_test_x_projected_d_rounds.svg", + "myrun_test_x_projected_d_rounds.pdf", + "myrun_test_x_per_round.svg", + "myrun_test_x_per_round.pdf", + } + actual_files = {path.name for path in tmp_path.iterdir() if path.suffix in (".svg", ".pdf")} + assert expected_files == actual_files + + +def test_fit_fss_threshold_recovers_synthetic_p_th(sweep: ModuleType) -> None: + """The Wang-Harrington-Preskill FSS fit must recover a known synthetic ``p_th``. + + Generates noise-free LER values on a grid of ``(p, d)`` points using the exact + polynomial form the fitter targets, then checks that the returned ``p_th`` and + ``nu`` match the generator's values within the fit's reported standard error. + + Skipped when ``pecos.analysis`` is not importable (happens in pytest because + ``tests/pecos/`` shadows the installed ``pecos`` package). + """ + pytest.importorskip("pecos.analysis.threshold_curve", reason="pecos.analysis shadowed by test-tree pecos/") + true_p_th = 0.010 + true_nu = 1.3 + true_a, true_b, true_c = 0.02, 1.2, 12.0 + + summaries: list[object] = [] + for d in (3, 5, 7, 9): + for p in (0.006, 0.008, 0.009, 0.010, 0.011, 0.012, 0.014): + x = (p - true_p_th) * (d ** (1.0 / true_nu)) + eps = true_a + true_b * x + true_c * x * x + if eps <= 0.0: + continue + summaries.append(_make_summary(sweep, distance=d, p=p, epsilon_per_round=eps, basis="X")) + + fit = sweep._fit_fss_threshold(summaries, seed_threshold=0.011, seed_nu=1.0) + assert fit is not None + assert fit.p_th == pytest.approx(true_p_th, abs=max(3.0 * fit.p_th_std_error, 5e-4)) + assert fit.nu == pytest.approx(true_nu, abs=max(3.0 * fit.nu_std_error, 0.2)) + assert fit.num_points >= 5 + assert fit.fit_window_low > 0.0 + assert fit.fit_window_high > fit.fit_window_low + + +def test_fit_fss_threshold_returns_none_without_enough_data(sweep: ModuleType) -> None: + """Too few near-threshold points -> FSS fitter returns ``None`` (caller can fall back).""" + summaries = [ + _make_summary(sweep, distance=3, p=0.010, epsilon_per_round=1e-3), + _make_summary(sweep, distance=5, p=0.010, epsilon_per_round=8e-4), + ] + fit = sweep._fit_fss_threshold(summaries, seed_threshold=0.010) + assert fit is None + + +def test_power_law_fit_respects_max_physical_error_rate(sweep: ModuleType) -> None: + """Filtering to ``p <= p_th`` must drop above-threshold points that flatten the fit. + + Simulates a clean below-threshold power law (c=3) combined with a set of + above-threshold points where the curve visibly flattens (saturating toward + a weaker power of p). Restricting the fit via ``max_physical_error_rate`` + must recover the true below-threshold exponent; the unrestricted fit + gets pulled toward the flatter above-threshold slope. + """ + true_exponent = 3.0 + prefactor = 1.0 + summaries: list[object] = [] + for p in (0.002, 0.003, 0.004, 0.005, 0.006): + eps = prefactor * (p**true_exponent) + summaries.append(_make_summary(sweep, distance=5, p=p, epsilon_per_round=eps, basis="X")) + # Above-threshold points visibly saturating -- eps grows much slower with p, + # dragging the unrestricted OLS slope below the clean c=3. + for p, eps in ((0.010, 3.0e-7), (0.012, 3.5e-7), (0.015, 4.0e-7)): + summaries.append(_make_summary(sweep, distance=5, p=p, epsilon_per_round=eps, basis="X")) + + unrestricted = sweep._fit_per_distance_power_law(summaries) + restricted = sweep._fit_per_distance_power_law(summaries, max_physical_error_rate=0.007) + + assert len(unrestricted) == 1 + assert len(restricted) == 1 + # Unrestricted fit gets pulled toward the flatter above-threshold slope. + assert unrestricted[0].fitted_exponent < true_exponent - 0.5 + # Restricted fit recovers the true exponent within tolerance. + assert restricted[0].fitted_exponent == pytest.approx(true_exponent, abs=0.05) + # Standard error is populated and sensible for this clean synthetic data. + assert restricted[0].fitted_exponent_std_error >= 0.0 + assert restricted[0].fitted_exponent_std_error < 0.1 + + +def test_estimate_threshold_uses_per_round_crossing(sweep: ModuleType) -> None: + """Threshold estimate must cross where per-round rates match, not the d-scaled metric. + + Using ``fitted_projected_logical_error_rate_over_d_rounds`` (roughly ``d * eps``) + makes the large-d curve overtake the small-d curve at a lower ``p`` than the true + threshold, so the estimator would underreport. Per-round rates are the canonical + definition. + """ + # Below threshold (p=0.004, 0.008): d=3 per-round > d=9 per-round. + # Above threshold (p=0.012): d=9 per-round > d=3 per-round. + # True crossing lives between p=0.008 and p=0.012. + summaries = [ + _make_summary(sweep, distance=3, p=0.004, epsilon_per_round=5.0e-3), + _make_summary(sweep, distance=9, p=0.004, epsilon_per_round=1.0e-3), + _make_summary(sweep, distance=3, p=0.008, epsilon_per_round=7.0e-3), + _make_summary(sweep, distance=9, p=0.008, epsilon_per_round=5.0e-3), + _make_summary(sweep, distance=3, p=0.012, epsilon_per_round=9.0e-3), + _make_summary(sweep, distance=9, p=0.012, epsilon_per_round=1.2e-2), + ] + threshold = sweep._estimate_threshold(summaries) + assert threshold is not None + assert 0.008 < threshold < 0.012 + + +def test_merge_sweep_shards_sums_shots_and_refits(sweep: ModuleType, tmp_path: Path) -> None: + """Two shards with the same config must merge to combined shot counts and a consistent fit.""" + import dataclasses + + # Build one shard: three rounds at d=5, X basis, p=0.005, epsilon=2e-3. + true_rate = 2.0e-3 + + def _shard_points(num_shots: int) -> list[object]: + return [ + sweep.SweepPoint( + backend="test", + distance=5, + basis="X", + physical_error_rate=0.005, + total_rounds=r, + num_shots=num_shots, + num_logical_errors=round(sweep.ler_over_rounds(true_rate, r) * num_shots), + num_raw_errors=None, + logical_error_rate=sweep.ler_over_rounds(true_rate, r), + raw_error_rate=None, + ) + for r in (10, 12, 14) + ] + + def _write_shard(name: str, points: list[object], shots_per_point: int) -> Path: + payload = { + "config": { + "distances": [5], + "bases": ["X"], + "error_rates": [0.005], + "shots": shots_per_point, + "executed_backends": ["test"], + "duration_rounds_by_distance": {"5": [10, 12, 14]}, + }, + "points": [dataclasses.asdict(point) for point in points], + "fit_summaries": [], + "timing_summary": { + "total_wall_clock_seconds": 10.0, + "total_shots": shots_per_point * len(points), + "total_points": len(points), + }, + } + path = tmp_path / name + path.write_text(json.dumps(payload)) + return path + + shard_a = _write_shard("a_results.json", _shard_points(2000), 2000) + shard_b = _write_shard("b_results.json", _shard_points(3000), 3000) + + points, summaries, config, timing = sweep.merge_sweep_shards([shard_a, shard_b]) + + # Three merged points (one per total_rounds value), each with summed shots. + assert len(points) == 3 + for point in points: + assert point.num_shots == 5000 # 2000 + 3000 under the same key + # Re-derived fit recovers the underlying epsilon within tolerance. + assert len(summaries) == 1 + fitted = summaries[0].fitted_logical_error_rate_per_round + assert fitted == pytest.approx(true_rate, rel=5e-3) + # Merged timing totals should sum across shards. + assert timing["total_wall_clock_seconds"] == pytest.approx(20.0) + assert timing["total_shots"] == 5000 * 3 # three points, each 5000 merged shots + # Config provenance records the shard paths and their individual shot counts. + assert len(config["source_shards"]) == 2 + assert {entry["shots"] for entry in config["source_shards"]} == {2000, 3000} + + +def test_merge_heterogeneous_shards_no_keyerror(sweep: ModuleType, tmp_path: Path) -> None: + """Merging shards with different distances/error_rates must not KeyError on grid holes.""" + import dataclasses + + true_rate = 2.0e-3 + + def _make_shard_points(distance: int, p: float, num_shots: int) -> list[object]: + return [ + sweep.SweepPoint( + backend="test", + distance=distance, + basis="X", + physical_error_rate=p, + total_rounds=r, + num_shots=num_shots, + num_logical_errors=round(sweep.ler_over_rounds(true_rate, r) * num_shots), + num_raw_errors=None, + logical_error_rate=sweep.ler_over_rounds(true_rate, r), + raw_error_rate=None, + ) + for r in (10, 12, 14) + ] + + def _write_shard(name: str, distance: int, p: float, num_shots: int) -> Path: + points = _make_shard_points(distance, p, num_shots) + payload = { + "config": { + "distances": [distance], + "bases": ["X"], + "error_rates": [p], + "shots": num_shots, + "executed_backends": ["test"], + "duration_rounds_by_distance": {str(distance): [10, 12, 14]}, + }, + "points": [dataclasses.asdict(pt) for pt in points], + "fit_summaries": [], + "timing_summary": { + "total_wall_clock_seconds": 5.0, + "total_shots": num_shots * len(points), + "total_points": len(points), + }, + } + path = tmp_path / name + path.write_text(json.dumps(payload)) + return path + + # Shard A has d=3, p=0.005; shard B has d=5, p=0.006. + # The merged grid has holes: (d=3, p=0.006) and (d=5, p=0.005) are absent. + shard_a = _write_shard("a_results.json", distance=3, p=0.005, num_shots=1000) + shard_b = _write_shard("b_results.json", distance=5, p=0.006, num_shots=1000) + + # This must not raise KeyError despite the sparse grid. + points, summaries, config, _timing = sweep.merge_sweep_shards([shard_a, shard_b]) + + assert len(points) == 6 # 3 rounds x 2 (d, p) combos + assert len(summaries) == 2 # one fit per (d, basis, p) + # Config should union distances and error_rates. + assert sorted(config["distances"]) == [3, 5] + assert sorted(config["error_rates"]) == [0.005, 0.006] + + # Verify that suppression_summary, print_basis_table, and build_plot_figure + # all tolerate the sparse grid without raising KeyError. + suppression = sweep._suppression_summary(summaries) + # With one distance per error rate, no suppression rows are produced (need >= 2 distances). + assert isinstance(suppression, list) + + # _print_basis_table should print without error (prints to stdout). + sweep._print_basis_table( + summaries, + metric="fitted_logical_error_rate_per_round", + title="Test heterogeneous table", + ) + + +def test_write_pdf_report_produces_multipage_pdf(sweep: ModuleType, tmp_path: Path) -> None: + """``write_pdf_report`` should produce a non-trivial PDF (cover + plot pages).""" + points = [ + sweep.SweepPoint( + backend="test", + distance=d, + basis="X", + physical_error_rate=0.005, + total_rounds=r, + num_shots=1000, + num_logical_errors=int(0.02 * 1000), + num_raw_errors=None, + logical_error_rate=0.02, + raw_error_rate=None, + ) + for d in (3, 5) + for r in (6, 8) + ] + summaries = [ + _make_summary(sweep, distance=d, p=0.005, epsilon_per_round=eps, basis="X") + for d, eps in [(3, 4.0e-3), (5, 2.0e-3)] + ] + config = { + "distances": [3, 5], + "error_rates": [0.005], + "shots": 1000, + "duration_schedule_description": "test schedule", + "duration_rounds_by_distance": {3: [6, 8], 5: [6, 8]}, + } + timing = {"overall_shots_per_second": 1234.5, "total_shots": 4000, "total_wall_clock_seconds": 3.24} + + report_path = tmp_path / "myrun_report.pdf" + written = sweep.write_pdf_report( + report_path, + points=points, + summaries=summaries, + timing_summary=timing, + config=config, + ) + assert written == report_path + assert report_path.is_file() + # Sanity check: a PDF with cover + at least one plot is much larger than an empty file. + assert report_path.stat().st_size > 4000 + # Confirm it's a real PDF by header magic, not an empty/corrupt file. + assert report_path.read_bytes()[:4] == b"%PDF" + + +def test_rebuild_plot_order_matches_primary_order(tmp_path: Path) -> None: + """Companion report script must match the primary writer's plot ordering.""" + example_dir = _repo_root() / "examples" / "surface" + sys.path.insert(0, str(example_dir)) + try: + import surface_sweep_report as report_mod + finally: + sys.path.pop(0) + + # Fake SVG artifacts matching what the primary writer produces. The primary + # writer emits, in order: per_round_overlay (combined), duration_overlay + # (duration), then per (backend, basis): projected_d_rounds, then per_round. + prefix = "surface_threshold_sweep" + backend = "native_sampler" + filenames = [ + f"{prefix}_{backend}_per_round_overlay.svg", + f"{prefix}_{backend}_p_0p006_duration_overlay.svg", + f"{prefix}_{backend}_x_projected_d_rounds.svg", + f"{prefix}_{backend}_x_per_round.svg", + f"{prefix}_{backend}_z_projected_d_rounds.svg", + f"{prefix}_{backend}_z_per_round.svg", + ] + for name in filenames: + (tmp_path / name).write_text('') + + plots = report_mod._discover_dashboard_plots(tmp_path, backends=[backend]) + discovered_names = [plot.filename for plot in plots] + assert discovered_names == filenames diff --git a/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py b/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py new file mode 100644 index 000000000..18f823e43 --- /dev/null +++ b/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py @@ -0,0 +1,1009 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Random circuit fuzzing comparing physical and logical PECOS simulations. + +Generates random stabilizer circuits, runs them at two levels: +1. Physical: single-qubit PECOS SparseStab (ground truth) +2. Logical: encoded in a surface code via LogicalCircuitBuilder, + TickCircuit replayed on SparseStab with detector/tracked-op checking + +No Stim dependency. Pure PECOS end-to-end. +""" + +from __future__ import annotations + +import json +import random + +import pytest +from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch +from pecos_rslib import SparseStab +from pecos_rslib.quantum import TickCircuit + +# --------------------------------------------------------------------------- +# TickCircuit simulation on SparseStab +# --------------------------------------------------------------------------- + + +def simulate_tick_circuit(tc: TickCircuit, seed: int = 0) -> tuple[list[int], int, dict[int, int]]: + """Simulate a TickCircuit on PECOS SparseStab. + + Returns (flat_measurements, det_fired, observable_values). + """ + max_q = 0 + for i in range(tc.num_ticks()): + for g in tc.get_tick(i).gates(): + for q in g.qubits: + max_q = max(max_q, int(q)) + + sim = SparseStab(max_q + 1) + sim.set_seed(seed) + flat = [] + + for i in range(tc.num_ticks()): + for g in tc.get_tick(i).gates(): + name = g.gate_type.name + qs = [int(q) for q in g.qubits] + if name == "QAlloc": + pass + elif name == "PZ": + sim.run_gate("PZ", set(qs)) + elif name == "MZ": + for q in qs: + r = sim.run_gate("MZ", {q}) + flat.append(r.get(q, 0)) + elif name in ("CX", "CZ"): + pairs = {(qs[j], qs[j + 1]) for j in range(0, len(qs), 2)} + sim.run_gate(name, pairs) + else: + sim.run_gate(name, set(qs)) + + num_meas = int(tc.get_meta("num_measurements")) + + # Check detectors + det_fired = 0 + det_json = tc.get_meta("detectors") + if det_json: + for det in json.loads(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(flat): + val ^= flat[idx] + if val != 0: + det_fired += 1 + + # Extract observables + obs_vals = {} + obs_json = tc.get_meta("observables") + if obs_json: + for obs in json.loads(obs_json): + val = 0 + for rec in obs["records"]: + idx = num_meas + rec + if 0 <= idx < len(flat): + val ^= flat[idx] + obs_vals[obs["id"]] = val + + return flat, det_fired, obs_vals + + +def physical_sim_1q(gates: list[str], init_basis: str, meas_basis: str) -> int: + """Single-qubit ground truth on SparseStab.""" + sim = SparseStab(1) + if init_basis == "X": + sim.run_gate("H", {0}) + for g in gates: + sim.run_gate(g, {0}) + if meas_basis == "X": + sim.run_gate("H", {0}) + return sim.run_gate("MZ", {0}).get(0, 0) + + +# --------------------------------------------------------------------------- +# Fixtures +# --------------------------------------------------------------------------- + + +@pytest.fixture +def patch(): + return SurfacePatch.create(distance=3) + + +@pytest.fixture +def nq(patch): + return patch.geometry.num_data + patch.geometry.num_ancilla + + +# --------------------------------------------------------------------------- +# Deterministic gate correctness (observable values) +# --------------------------------------------------------------------------- + + +class TestGateCorrectness: + """Verify gate observables match physical ground truth (pure PECOS).""" + + def test_memory_z(self, patch): + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", 2, "Z") + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == 0 + + def test_memory_x(self, patch): + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", 2, "X") + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == 0 + + def test_h_z_to_x(self, patch): + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", 2, "Z") + b.add_transversal_h("A") + b.add_memory("A", 2, "X") + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == 0 + + def test_h_x_to_z(self, patch): + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", 2, "X") + b.add_transversal_h("A") + b.add_memory("A", 2, "Z") + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == 0 + + def test_hh_identity(self, patch): + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", 2, "Z") + b.add_transversal_h("A") + b.add_memory("A", 2, "X") + b.add_transversal_h("A") + b.add_memory("A", 2, "Z") + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == 0 + + def test_cx_00_zz(self, patch, nq): + b = LogicalCircuitBuilder() + b.add_patch(patch, "C", qubit_offset=0) + b.add_patch(patch, "T", qubit_offset=nq) + b.add_memory(["C", "T"], 2, "Z") + b.add_transversal_cx("C", "T") + b.add_memory(["C", "T"], 2, "Z") + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == 0 and obs[1] == 0 + + def test_cx_pp_xx(self, patch, nq): + b = LogicalCircuitBuilder() + b.add_patch(patch, "C", qubit_offset=0) + b.add_patch(patch, "T", qubit_offset=nq) + b.add_memory(["C", "T"], 2, "X") + b.add_transversal_cx("C", "T") + b.add_memory(["C", "T"], 2, "X") + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == 0 and obs[1] == 0 + + +# --------------------------------------------------------------------------- +# Noiseless detector validity (multiple seeds) +# --------------------------------------------------------------------------- + + +class TestNoiselessDetectors: + """Verify 0 detector fires across many seeds (PECOS-only).""" + + @pytest.mark.parametrize("seed", range(20)) + def test_memory_z(self, patch, seed): + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", 3, "Z") + _, det, _ = simulate_tick_circuit(b.to_tick_circuit(), seed) + assert det == 0 + + @pytest.mark.parametrize("seed", range(20)) + def test_h(self, patch, seed): + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", 2, "Z") + b.add_transversal_h("A") + b.add_memory("A", 2, "X") + _, det, _ = simulate_tick_circuit(b.to_tick_circuit(), seed) + assert det == 0 + + @pytest.mark.parametrize("seed", range(20)) + def test_cx(self, patch, nq, seed): + b = LogicalCircuitBuilder() + b.add_patch(patch, "C", qubit_offset=0) + b.add_patch(patch, "T", qubit_offset=nq) + b.add_memory(["C", "T"], 2, "Z") + b.add_transversal_cx("C", "T") + b.add_memory(["C", "T"], 2, "Z") + _, det, _ = simulate_tick_circuit(b.to_tick_circuit(), seed) + assert det == 0 + + +# --------------------------------------------------------------------------- +# Fuzz: physical vs logical H sequences +# --------------------------------------------------------------------------- + + +class TestFuzzH: + @pytest.mark.parametrize("seed", range(50)) + def test_random_h(self, patch, seed): + rng = random.Random(seed) + num_h = rng.randint(0, 8) + init_b = rng.choice(["Z", "X"]) + eff_b = init_b + for _ in range(num_h): + eff_b = "X" if eff_b == "Z" else "Z" + + expected = physical_sim_1q(["H"] * num_h, init_b, eff_b) + + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", 2, init_b) + cur = init_b + for _ in range(num_h): + b.add_transversal_h("A") + cur = "X" if cur == "Z" else "Z" + b.add_memory("A", 2, cur) + + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == expected + + +# --------------------------------------------------------------------------- +# Fuzz: H+CX composition +# --------------------------------------------------------------------------- + + +class TestFuzzCX: + """Fuzz CX with various init/meas bases against physical SparseStab.""" + + @pytest.mark.parametrize("seed", range(50)) + def test_random_cx(self, patch, nq, seed): + rng = random.Random(seed) + ic = rng.choice(["Z", "X"]) + it = rng.choice(["Z", "X"]) + mc = rng.choice(["Z", "X"]) + mt = rng.choice(["Z", "X"]) + + # Physical ground truth: detect deterministic outcomes + results = [] + for _ in range(50): + sim = SparseStab(2) + if ic == "X": + sim.run_gate("H", {0}) + if it == "X": + sim.run_gate("H", {1}) + sim.run_gate("CX", {(0, 1)}) + if mc == "X": + sim.run_gate("H", {0}) + if mt == "X": + sim.run_gate("H", {1}) + r = sim.run_gate("MZ", {0, 1}) + results.append((r.get(0, 0), r.get(1, 0))) + r0s, r1s = [r[0] for r in results], [r[1] for r in results] + exp0 = r0s[0] if len(set(r0s)) == 1 else None + exp1 = r1s[0] if len(set(r1s)) == 1 else None + + # Encoded + b = LogicalCircuitBuilder() + b.add_patch(patch, "C", qubit_offset=0) + b.add_patch(patch, "T", qubit_offset=nq) + b.add_memory(["C", "T"], 2, basis={"C": ic, "T": it}) + b.add_transversal_cx("C", "T") + b.add_memory(["C", "T"], 2, basis={"C": mc, "T": mt}) + + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0, f"Noiseless det fired: {ic}{it}->{mc}{mt}" + + if exp0 is not None and 0 in obs: + assert obs[0] == exp0, f"obs0: got {obs[0]} expected {exp0}" + if exp1 is not None and 1 in obs: + assert obs[1] == exp1, f"obs1: got {obs[1]} expected {exp1}" + + +class TestFuzzComposition: + @pytest.mark.parametrize("seed", range(30)) + def test_random_h_cx(self, patch, nq, seed): + rng = random.Random(seed) + num_ops = rng.randint(1, 6) + + b = LogicalCircuitBuilder() + b.add_patch(patch, "A", qubit_offset=0) + b.add_patch(patch, "B", qubit_offset=nq) + b.add_memory(["A", "B"], 2, "Z") + eff = {"A": "Z", "B": "Z"} + + for _ in range(num_ops): + op = rng.choice(["H_A", "H_B", "CX"]) + if op == "H_A": + b.add_transversal_h("A") + eff["A"] = "X" if eff["A"] == "Z" else "Z" + b.add_memory(["A", "B"], 2, basis={"A": eff["A"], "B": eff["B"]}) + elif op == "H_B": + b.add_transversal_h("B") + eff["B"] = "X" if eff["B"] == "Z" else "Z" + b.add_memory(["A", "B"], 2, basis={"A": eff["A"], "B": eff["B"]}) + else: + if eff["A"] != eff["B"]: + continue + b.add_transversal_cx("A", "B") + b.add_memory(["A", "B"], 2, basis={"A": eff["A"], "B": eff["B"]}) + + _, det, _ = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 + + +# --------------------------------------------------------------------------- +# Distance scaling +# --------------------------------------------------------------------------- + + +class TestDistanceScaling: + @pytest.fixture + def patch5(self): + return SurfacePatch.create(distance=5) + + @pytest.fixture + def nq5(self, patch5): + return patch5.geometry.num_data + patch5.geometry.num_ancilla + + def test_d5_memory(self, patch5): + b = LogicalCircuitBuilder() + b.add_patch(patch5, "A") + b.add_memory("A", 3, "Z") + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == 0 + + def test_d5_h(self, patch5): + b = LogicalCircuitBuilder() + b.add_patch(patch5, "A") + b.add_memory("A", 2, "Z") + b.add_transversal_h("A") + b.add_memory("A", 2, "X") + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == 0 + + @pytest.mark.parametrize("seed", range(5)) + def test_d5_cx(self, patch5, nq5, seed): + b = LogicalCircuitBuilder() + b.add_patch(patch5, "C", qubit_offset=0) + b.add_patch(patch5, "T", qubit_offset=nq5) + b.add_memory(["C", "T"], 2, "Z") + b.add_transversal_cx("C", "T") + b.add_memory(["C", "T"], 2, "Z") + _, det, obs = simulate_tick_circuit(b.to_tick_circuit(), seed) + assert det == 0 and obs[0] == 0 and obs[1] == 0 + + def test_d5_pecos_dem(self, patch5): + b = LogicalCircuitBuilder() + b.add_patch(patch5, "A") + b.add_memory("A", 2, "Z") + dem_str = b.build_dem(p1=0.001, p2=0.001, p_meas=0.001) + errors = [l for l in dem_str.split("\n") if l.startswith("error(")] + assert len(errors) > 0 + + +# --------------------------------------------------------------------------- +# TickCircuit structural tests +# --------------------------------------------------------------------------- + +# --------------------------------------------------------------------------- +# SZ teleportation +# --------------------------------------------------------------------------- + + +class TestReliableObservables: + """Verify that non-reliable observables are correctly skipped.""" + + def test_cx_same_basis_both_reliable(self, patch, nq): + """CX with same-basis measurements: both observables emitted.""" + b = LogicalCircuitBuilder() + b.add_patch(patch, "C", qubit_offset=0) + b.add_patch(patch, "T", qubit_offset=nq) + b.add_memory(["C", "T"], 2, "Z") + b.add_transversal_cx("C", "T") + b.add_memory(["C", "T"], 2, "Z") + tc = b.to_tick_circuit() + obs = json.loads(tc.get_meta("observables")) + assert len(obs) == 2, f"Expected 2 observables, got {len(obs)}" + + def test_cx_cross_basis_skips_unreliable(self, patch, nq): + """CX with cross-basis: non-deterministic observables skipped.""" + b = LogicalCircuitBuilder() + b.add_patch(patch, "C", qubit_offset=0) + b.add_patch(patch, "T", qubit_offset=nq) + b.add_memory(["C", "T"], 2, basis={"C": "X", "T": "Z"}) + b.add_transversal_cx("C", "T") + b.add_memory(["C", "T"], 2, basis={"C": "X", "T": "Z"}) + tc = b.to_tick_circuit() + obs = json.loads(tc.get_meta("observables")) + # Ctrl measured in X after CX: X_ctrl entangled with tgt (measured Z) + # → ctrl X observable is non-reliable → skipped + # Tgt measured in Z after CX: Z_tgt entangled with ctrl (measured X) + # → tgt Z observable is non-reliable → skipped + # Both should be skipped + assert len(obs) == 0, f"Expected 0 observables (both non-reliable), got {len(obs)}" + + def test_cx_zx_one_reliable(self, patch, nq): + """CX|0>|+> with meas(Z,X): both should be reliable. + + After CX: Z_ctrl unchanged, X_tgt unchanged. + Measuring ctrl in Z: reliable (Z not entangled). + Measuring tgt in X: reliable (X not entangled). + """ + b = LogicalCircuitBuilder() + b.add_patch(patch, "C", qubit_offset=0) + b.add_patch(patch, "T", qubit_offset=nq) + b.add_memory(["C", "T"], 2, basis={"C": "Z", "T": "X"}) + b.add_transversal_cx("C", "T") + b.add_memory(["C", "T"], 2, basis={"C": "Z", "T": "X"}) + tc = b.to_tick_circuit() + obs = json.loads(tc.get_meta("observables")) + assert len(obs) == 2, f"Expected 2 observables, got {len(obs)}" + + _, det, obs_vals = simulate_tick_circuit(tc) + assert det == 0 + assert obs_vals[0] == 0 and obs_vals[1] == 0 + + +class TestSZTeleportation: + def test_sz_preserves_z(self, patch, nq): + """SZ|0> = |0>: Z eigenvalue preserved.""" + b = LogicalCircuitBuilder() + b.add_patch(patch, "D", qubit_offset=0) + b.add_patch(patch, "Y", qubit_offset=nq) + b.add_memory("D", 2, "Z") + b.add_sz_via_teleportation("D", "Y", 2, 2) + b.add_memory("D", 2, "Z") + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == 0 + + def test_sz_phase_single_qubit(self): + """Verify SZ teleportation protocol at the single-qubit level. + + The phase test (SZ^2|+> = Z|+> = |->) cannot be verified at the + logical level because the |+Y> injection is non-fault-tolerant + (distance-1 error). But we CAN verify the protocol works on a + single physical qubit, confirming the circuit structure is correct. + """ + sim = SparseStab(3) + # Qubit 0: data (|+>), Qubit 1: ancilla 1 (|+Y>), Qubit 2: ancilla 2 (|+Y>) + + # Prep |+> + sim.run_gate("H", {0}) + # Prep |+Y> = S|+> + sim.run_gate("H", {1}) + sim.run_gate("SZ", {1}) + sim.run_gate("H", {2}) + sim.run_gate("SZ", {2}) + + # First teleportation: CX(data, anc1), measure anc1 in Z + sim.run_gate("CX", {(0, 1)}) + r1 = sim.run_gate("MZ", {1}) + m1 = r1.get(1, 0) + + # Second teleportation: CX(data, anc2), measure anc2 in Z + sim.run_gate("CX", {(0, 2)}) + r2 = sim.run_gate("MZ", {2}) + m2 = r2.get(2, 0) + + # Measure data in X basis: SZ^2|+> = Z|+> = |-> + sim.run_gate("H", {0}) + r_data = sim.run_gate("MZ", {0}) + data_val = r_data.get(0, 0) + + # Corrected observable: data_X XOR m1 XOR m2 + corrected = data_val ^ m1 ^ m2 + assert corrected == 1, ( + f"SZ^2|+> should give |-> (corrected=1), " f"got data={data_val} m1={m1} m2={m2} corrected={corrected}" + ) + + +# --------------------------------------------------------------------------- +# Gate composition +# --------------------------------------------------------------------------- + + +class TestGateComposition: + def test_h_cx_h(self, patch, nq): + """H -> CX -> H on both patches.""" + b = LogicalCircuitBuilder() + b.add_patch(patch, "A", qubit_offset=0) + b.add_patch(patch, "B", qubit_offset=nq) + b.add_memory(["A", "B"], 2, "Z") + b.add_transversal_h("A") + b.add_transversal_h("B") + b.add_memory(["A", "B"], 2, "X") + b.add_transversal_cx("A", "B") + b.add_memory(["A", "B"], 2, "X") + b.add_transversal_h("A") + b.add_transversal_h("B") + b.add_memory(["A", "B"], 2, "Z") + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == 0 and obs[1] == 0 + + def test_triple_h(self, patch): + """HHH = H: |0> -> |+>.""" + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", 2, "Z") + for i in range(3): + b.add_transversal_h("A") + cur = "X" if i % 2 == 0 else "Z" + b.add_memory("A", 2, cur) + _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) + assert det == 0 and obs[0] == 0 + + +# --------------------------------------------------------------------------- +# Decoder pipeline (PECOS-native) +# --------------------------------------------------------------------------- + + +class TestDecoderPipeline: + """Test the full decode pipeline using PECOS DEM + PECOS sampler.""" + + def test_build_decoder_pecos_dem(self, patch): + """build_decoder with PECOS-native DEM produces a working decoder.""" + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", 3, "Z") + _, decoder = b.build_decoder(p1=0.001, p2=0.001, p_meas=0.001, use_stim_dem=False) + assert decoder.num_observables() == 1 + + def test_pecos_dem_decode_memory(self, patch): + """End-to-end: PECOS DEM → PECOS sample → decode → low error rate.""" + from pecos_rslib.qec import ParsedDem + + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", 3, "Z") + dem_str = b.build_dem(p1=0.001, p2=0.001, p_meas=0.001) + + parsed = ParsedDem.from_string(dem_str) + rust_sampler = parsed.to_dem_sampler() + batch = rust_sampler.generate_samples(5000, seed=42) + errors = batch.decode_count(dem_str, "pecos_uf:fast") + ler = errors / 5000 + # At d=3 p=0.001, LER should be very low + assert ler < 0.05, f"LER too high: {ler}" + + def test_observable_subgraph_decoder(self, patch, nq): + """OSD with PECOS DEM on CX circuit.""" + from pecos_rslib.qec import ObservableSubgraphDecoder, ParsedDem + + b = LogicalCircuitBuilder() + b.add_patch(patch, "C", qubit_offset=0) + b.add_patch(patch, "T", qubit_offset=nq) + b.add_memory(["C", "T"], 3, "Z") + b.add_transversal_cx("C", "T") + b.add_memory(["C", "T"], 3, "Z") + + dem_str = b.build_dem(p1=0.001, p2=0.001, p_meas=0.001) + sc = b.stab_coords() + osd = ObservableSubgraphDecoder(dem_str, sc, "pecos_uf:fast") + assert osd.num_observables() == 2 + + sizes = osd.subgraph_sizes() + for s in sizes: + assert s > 0, "Empty subgraph" + + def test_pecos_dem_cx_decode(self, patch, nq): + """End-to-end CX: PECOS DEM → sample → decode.""" + from pecos_rslib.qec import ParsedDem + + b = LogicalCircuitBuilder() + b.add_patch(patch, "C", qubit_offset=0) + b.add_patch(patch, "T", qubit_offset=nq) + b.add_memory(["C", "T"], 3, "Z") + b.add_transversal_cx("C", "T") + b.add_memory(["C", "T"], 3, "Z") + + dem_str = b.build_dem(p1=0.001, p2=0.001, p_meas=0.001) + parsed = ParsedDem.from_string(dem_str) + rust_sampler = parsed.to_dem_sampler() + batch = rust_sampler.generate_samples(5000, seed=42) + errors = batch.decode_count(dem_str, "pecos_uf:fast") + ler = errors / 5000 + assert ler < 0.1, f"CX LER too high: {ler}" + + +# --------------------------------------------------------------------------- +# TickCircuit structural tests +# --------------------------------------------------------------------------- + +# --------------------------------------------------------------------------- +# Threshold: error suppression with distance (d=3 vs d=5) +# --------------------------------------------------------------------------- + + +class TestThreshold: + """Verify error suppression increases with distance. + + Uses Stim DEM for error mechanisms (more complete noise model) + and PECOS decoder for correction. Tests at p=0.001 where we should + be well below threshold. + """ + + def _run_threshold(self, builder, d, decoder_type="pecos_uf:fast"): + import stim + from pecos_rslib.qec import ParsedDem + + c = stim.Circuit(builder.to_stim(p1=0.001, p2=0.001, p_meas=0.001)) + dem = c.detector_error_model(decompose_errors=True, ignore_decomposition_failures=True) + dem_str = str(dem) + parsed = ParsedDem.from_string(dem_str) + sampler = parsed.to_dem_sampler() + batch = sampler.generate_samples(20000, seed=42) + errors = batch.decode_count(dem_str, decoder_type) + return errors / 20000 + + def test_memory_suppression(self): + """Memory: d=5 should have lower LER than d=3.""" + lers = {} + for d in [3, 5]: + patch = SurfacePatch.create(distance=d) + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", rounds=d, basis="Z") + lers[d] = self._run_threshold(b, d, "pymatching") + assert lers[5] < lers[3], f"d=5 ({lers[5]}) not better than d=3 ({lers[3]})" + + def test_h_suppression(self): + """H gate: d=5 should have lower LER than d=3.""" + lers = {} + for d in [3, 5]: + patch = SurfacePatch.create(distance=d) + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", rounds=d, basis="Z") + b.add_transversal_h("A") + b.add_memory("A", rounds=d, basis="X") + lers[d] = self._run_threshold(b, d, "pymatching") + assert lers[5] < lers[3], f"d=5 ({lers[5]}) not better than d=3 ({lers[3]})" + + +# --------------------------------------------------------------------------- +# TickCircuit structural tests +# --------------------------------------------------------------------------- + +# --------------------------------------------------------------------------- +# Noisy fuzz: random circuits decode with reasonable error rates +# --------------------------------------------------------------------------- + + +class TestNoisyFuzz: + """Verify that random circuits with noise decode with sub-50% error rate. + + This is a basic sanity check: if the decoder is completely broken, + the LER would be ~50%. Any reasonable decoder should do much better. + """ + + @pytest.mark.parametrize("seed", range(5)) + def test_noisy_h(self, patch, seed): + import stim + from pecos_rslib.qec import ParsedDem + + rng = random.Random(seed) + num_h = rng.randint(1, 4) + init_b = "Z" + b = LogicalCircuitBuilder() + b.add_patch(patch, "A") + b.add_memory("A", 2, init_b) + cur = init_b + for _ in range(num_h): + b.add_transversal_h("A") + cur = "X" if cur == "Z" else "Z" + b.add_memory("A", 2, cur) + + c = stim.Circuit(b.to_stim(p1=0.001, p2=0.001, p_meas=0.001)) + dem = c.detector_error_model(decompose_errors=True) + dem_str = str(dem) + parsed = ParsedDem.from_string(dem_str) + batch = parsed.to_dem_sampler().generate_samples(5000, seed=seed) + errors = batch.decode_count(dem_str, "pecos_uf:fast") + ler = errors / 5000 + assert ler < 0.1, f"LER too high: {ler}" + + +# --------------------------------------------------------------------------- +# TickCircuit structural tests +# --------------------------------------------------------------------------- + +# --------------------------------------------------------------------------- +# Composed noisy gate sequences +# --------------------------------------------------------------------------- + + +class TestNoisyComposition: + """Verify that multi-gate sequences with noise decode correctly.""" + + def test_noisy_h_cx_h(self, patch, nq): + """H -> CX -> H with noise: should decode with low LER.""" + import stim + from pecos_rslib.qec import ParsedDem + + b = LogicalCircuitBuilder() + b.add_patch(patch, "A", qubit_offset=0) + b.add_patch(patch, "B", qubit_offset=nq) + b.add_memory(["A", "B"], 2, "Z") + b.add_transversal_h("A") + b.add_transversal_h("B") + b.add_memory(["A", "B"], 2, "X") + b.add_transversal_cx("A", "B") + b.add_memory(["A", "B"], 2, "X") + b.add_transversal_h("A") + b.add_transversal_h("B") + b.add_memory(["A", "B"], 2, "Z") + + # Use Stim DEM (more error mechanisms) for noisy test + c = stim.Circuit(b.to_stim(p1=0.001, p2=0.001, p_meas=0.001)) + dem = c.detector_error_model(decompose_errors=True, ignore_decomposition_failures=True) + dem_str = str(dem) + parsed = ParsedDem.from_string(dem_str) + batch = parsed.to_dem_sampler().generate_samples(10000, seed=42) + errors = batch.decode_count(dem_str, "pecos_uf:fast") + ler = errors / 10000 + assert ler < 0.1, f"H-CX-H LER too high: {ler}" + + @pytest.mark.parametrize("seed", range(5)) + def test_noisy_random_composition(self, patch, nq, seed): + """Random H+CX with noise: should decode with sub-50% LER.""" + import stim + from pecos_rslib.qec import ParsedDem + + rng = random.Random(seed) + b = LogicalCircuitBuilder() + b.add_patch(patch, "A", qubit_offset=0) + b.add_patch(patch, "B", qubit_offset=nq) + b.add_memory(["A", "B"], 2, "Z") + eff = {"A": "Z", "B": "Z"} + + for _ in range(rng.randint(1, 4)): + op = rng.choice(["H_A", "H_B", "CX"]) + if op == "H_A": + b.add_transversal_h("A") + eff["A"] = "X" if eff["A"] == "Z" else "Z" + b.add_memory(["A", "B"], 2, basis={"A": eff["A"], "B": eff["B"]}) + elif op == "H_B": + b.add_transversal_h("B") + eff["B"] = "X" if eff["B"] == "Z" else "Z" + b.add_memory(["A", "B"], 2, basis={"A": eff["A"], "B": eff["B"]}) + else: + if eff["A"] != eff["B"]: + continue + b.add_transversal_cx("A", "B") + b.add_memory(["A", "B"], 2, basis={"A": eff["A"], "B": eff["B"]}) + + c = stim.Circuit(b.to_stim(p1=0.001, p2=0.001, p_meas=0.001)) + dem = c.detector_error_model(decompose_errors=True, ignore_decomposition_failures=True) + dem_str = str(dem) + parsed = ParsedDem.from_string(dem_str) + batch = parsed.to_dem_sampler().generate_samples(5000, seed=42) + errors = batch.decode_count(dem_str, "pecos_uf:fast") + ler = errors / 5000 + assert ler < 0.2, f"Random composition LER too high: {ler}" + + +# --------------------------------------------------------------------------- +# OSD accuracy comparison +# --------------------------------------------------------------------------- + + +class TestOSDAccuracy: + """Compare observable subgraph decoder accuracy against baseline.""" + + def test_osd_better_than_naive_on_cx(self, patch, nq): + """OSD should outperform naive decomposed MWPM on CX circuits.""" + import stim + from pecos_rslib.qec import ObservableSubgraphDecoder, ParsedDem + + b = LogicalCircuitBuilder() + b.add_patch(patch, "C", qubit_offset=0) + b.add_patch(patch, "T", qubit_offset=nq) + b.add_memory(["C", "T"], 3, "Z") + b.add_transversal_cx("C", "T") + b.add_memory(["C", "T"], 3, "Z") + + c = stim.Circuit(b.to_stim(p1=0.001, p2=0.001, p_meas=0.001)) + dem = c.detector_error_model(ignore_decomposition_failures=True) + dem_str = str(dem) + + # Sample + sampler = dem.compile_sampler() + det_events, obs_flips, _ = sampler.sample(20000) + + # Naive: decomposed MWPM via PECOS UF + dem_decomp = c.detector_error_model(decompose_errors=True, ignore_decomposition_failures=True) + parsed = ParsedDem.from_string(str(dem_decomp)) + batch_naive = parsed.to_dem_sampler().generate_samples(20000, seed=42) + naive_errors = batch_naive.decode_count(str(dem_decomp), "pecos_uf:fast") + naive_ler = naive_errors / 20000 + + # OSD with FB + sc = b.stab_coords() + osd = ObservableSubgraphDecoder(dem_str, sc, "fusion_blossom_serial") + osd_errors = sum( + 1 + for i in range(20000) + if osd.decode(det_events[i].tolist()) != sum((1 << j) for j in range(obs_flips.shape[1]) if obs_flips[i, j]) + ) + osd_ler = osd_errors / 20000 + + # OSD should be at least as good (usually much better) + assert osd_ler <= naive_ler * 1.5 + 0.001, f"OSD ({osd_ler:.5f}) much worse than naive ({naive_ler:.5f})" + + +# --------------------------------------------------------------------------- +# PECOS-native DEM with OSD decoder on CX +# --------------------------------------------------------------------------- + + +class TestPecosDemWithOSD: + """Test PECOS-native DEM pipeline with observable subgraph decoder.""" + + def test_pecos_dem_osd_cx(self, patch, nq): + """PECOS DEM → OSD decoder on CX circuit.""" + from pecos_rslib.qec import ObservableSubgraphDecoder, ParsedDem + + b = LogicalCircuitBuilder() + b.add_patch(patch, "C", qubit_offset=0) + b.add_patch(patch, "T", qubit_offset=nq) + b.add_memory(["C", "T"], 3, "Z") + b.add_transversal_cx("C", "T") + b.add_memory(["C", "T"], 3, "Z") + + dem_str = b.build_dem(p1=0.001, p2=0.001, p_meas=0.001) + + # Verify DEM has content + errors = [l for l in dem_str.split("\n") if l.startswith("error(")] + assert len(errors) > 0 + + # Build OSD decoder from PECOS DEM + sc = b.stab_coords() + osd = ObservableSubgraphDecoder(dem_str, sc, "pecos_uf:fast") + assert osd.num_observables() == 2 + + # Sample and decode + parsed = ParsedDem.from_string(dem_str) + batch = parsed.to_dem_sampler().generate_samples(5000, seed=42) + errors = batch.decode_count(dem_str, "pecos_uf:fast") + ler = errors / 5000 + assert ler < 0.1, f"PECOS DEM + OSD CX LER too high: {ler}" + + +# --------------------------------------------------------------------------- +# TickCircuit structural tests +# --------------------------------------------------------------------------- + +# --------------------------------------------------------------------------- +# Mirrored brickwork circuits +# --------------------------------------------------------------------------- + + +def _build_mirrored_brickwork(num_qubits, depth, seed, patch, rounds=2): + """Build a mirrored brickwork circuit (identity, output = |0...0>). + + Forward: random H gates + CX brickwork layers. + Mirror: exact reverse (H and CX are self-inverse). + """ + nq = patch.geometry.num_data + patch.geometry.num_ancilla + + b = LogicalCircuitBuilder() + labels = [f"Q{i}" for i in range(num_qubits)] + for i, label in enumerate(labels): + b.add_patch(patch, label, qubit_offset=i * nq) + + eff = dict.fromkeys(labels, "Z") + b.add_memory(labels, rounds, "Z") + + rng = random.Random(seed) + ops_forward = [] + + for layer in range(depth): + layer_ops = [] + for label in labels: + # H is the only single-qubit logical gate available. + # SZ requires teleportation (not a standalone gate on the surface code). + if rng.random() < 0.5: + b.add_transversal_h(label) + eff[label] = "X" if eff[label] == "Z" else "Z" + layer_ops.append(("H", label)) + b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + + offset = layer % 2 + cx_applied = [] + for i in range(offset, num_qubits - 1, 2): + ctrl, tgt = labels[i], labels[i + 1] + if eff[ctrl] == eff[tgt]: + b.add_transversal_cx(ctrl, tgt) + cx_applied.append((ctrl, tgt)) + if cx_applied: + b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + layer_ops.append(("CX", cx_applied)) + ops_forward.append(layer_ops) + + for layer_ops in reversed(ops_forward): + for op_type, *args in reversed(layer_ops): + if op_type == "CX": + for ctrl, tgt in reversed(args[0]): + if eff[ctrl] == eff[tgt]: + b.add_transversal_cx(ctrl, tgt) + b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + for op_type, *args in reversed(layer_ops): + if op_type == "H": + label = args[0] + b.add_transversal_h(label) + eff[label] = "X" if eff[label] == "Z" else "Z" + b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + + return b + + +class TestMirroredBrickwork: + """Mirrored brickwork circuits: identity circuit, output always |0...0>. + + Tests random H + CX brickwork layers at various widths and depths. + The mirror guarantees the output is |0...0> regardless of random choices. + """ + + @pytest.mark.parametrize("width", [2, 3, 4]) + @pytest.mark.parametrize("depth", [1, 2, 3]) + @pytest.mark.parametrize("seed", range(5)) + def test_brickwork_d3(self, width, depth, seed): + patch = SurfacePatch.create(distance=3) + b = _build_mirrored_brickwork(width, depth, seed, patch) + tc = b.to_tick_circuit() + det_fired, obs_vals = simulate_tick_circuit(tc, seed)[-2:] + assert det_fired == 0, f"w={width} d={depth}: {det_fired} detectors fired" + for obs_id, val in obs_vals.items(): + assert val == 0, f"w={width} d={depth}: obs{obs_id}={val}" + + @pytest.mark.parametrize("width", [2, 3]) + @pytest.mark.parametrize("seed", range(3)) + def test_brickwork_d5(self, width, seed): + patch = SurfacePatch.create(distance=5) + b = _build_mirrored_brickwork(width, 2, seed, patch) + tc = b.to_tick_circuit() + det_fired, obs_vals = simulate_tick_circuit(tc, seed)[-2:] + assert det_fired == 0 + for obs_id, val in obs_vals.items(): + assert val == 0 + + +# --------------------------------------------------------------------------- +# TickCircuit structural tests +# --------------------------------------------------------------------------- + + +class TestTickCircuitStructure: + @pytest.mark.parametrize("num_qubits", [1, 2, 3, 5, 8]) + @pytest.mark.parametrize("depth", [10, 30]) + @pytest.mark.parametrize("seed", range(3)) + def test_build_roundtrip(self, num_qubits, depth, seed): + gate_set = ["H", "SZ", "X", "Z"] + if num_qubits >= 2: + gate_set.extend(["CX", "CZ"]) + rng = random.Random(seed) + tc = TickCircuit() + t = tc.tick() + t.qalloc(list(range(num_qubits))) + for _ in range(depth): + gate = rng.choice(gate_set) + t = tc.tick() + if gate in ("CX", "CZ"): + q1, q2 = rng.sample(range(num_qubits), 2) + getattr(t, gate.lower())([(q1, q2)]) + else: + q = rng.randint(0, num_qubits - 1) + getattr(t, gate.lower())([q]) + t = tc.tick() + t.mz(list(range(num_qubits))) + assert tc.num_ticks() >= 2 diff --git a/python/quantum-pecos/tests/qec/surface/test_surface_decoder.py b/python/quantum-pecos/tests/qec/surface/test_surface_decoder.py index 9fc095466..dad4f92aa 100644 --- a/python/quantum-pecos/tests/qec/surface/test_surface_decoder.py +++ b/python/quantum-pecos/tests/qec/surface/test_surface_decoder.py @@ -16,11 +16,40 @@ NoiseModel, SurfaceDecoder, SurfacePatch, + generate_dem_from_tick_circuit, generate_surface_code_dem, + generate_tick_circuit_from_patch, syndromes_to_detection_events, ) +def _require_selene_runtime() -> None: + """Eagerly instantiate the Selene engine to fail fast if it is unavailable. + + The PECOS test environment is expected to have the Selene runtime installed + (see ``pecos setup``). A failure here means the environment is broken, not + that the test should be skipped. + """ + import pecos + + pecos.selene_engine() + + +def _count_singleton_error_parts(dem: str) -> int: + """Count decomposed error parts that touch exactly one detector.""" + count = 0 + for line in dem.splitlines(): + stripped = line.strip() + if not stripped.startswith("error("): + continue + payload = stripped.split(")", 1)[1] + for part in payload.split("^"): + detectors = [token for token in part.split() if token.startswith("D")] + if len(detectors) == 1: + count += 1 + return count + + class TestNoiseModel: """Tests for NoiseModel dataclass.""" @@ -30,7 +59,7 @@ def test_default_values(self) -> None: assert noise.p1 == 0.0 assert noise.p2 == 0.0 assert noise.p_meas == 0.0 - assert noise.p_init == 0.0 + assert noise.p_prep == 0.0 def test_is_noiseless(self) -> None: """Test is_noiseless property.""" @@ -38,11 +67,11 @@ def test_is_noiseless(self) -> None: assert not NoiseModel(p1=0.01).is_noiseless assert not NoiseModel(p2=0.01).is_noiseless assert not NoiseModel(p_meas=0.01).is_noiseless - assert not NoiseModel(p_init=0.01).is_noiseless + assert not NoiseModel(p_prep=0.01).is_noiseless def test_physical_error_rate(self) -> None: """Test physical_error_rate property.""" - noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.005, p_init=0.002) + noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.005, p_prep=0.002) assert noise.physical_error_rate == 0.01 # max of all rates @@ -178,6 +207,35 @@ def test_get_dem(self) -> None: assert "error" in pheno_dem assert "detector" in pheno_dem + def test_get_dem_caches_circuit_level_dem(self, monkeypatch: pytest.MonkeyPatch) -> None: + """Repeated circuit-level DEM requests should reuse the decoder-local cache.""" + import pecos.qec.surface.decode as decode_module + + patch = SurfacePatch.create(distance=3) + noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.01, p_prep=0.001) + decoder = SurfaceDecoder( + patch, + num_rounds=3, + noise=noise, + circuit_level_dem_mode="native_decomposed", + ) + + real_generate = decode_module.generate_circuit_level_dem_from_builder + calls = 0 + + def wrapped_generate(*args: object, **kwargs: object) -> str: + nonlocal calls + calls += 1 + return real_generate(*args, **kwargs) + + monkeypatch.setattr(decode_module, "generate_circuit_level_dem_from_builder", wrapped_generate) + + dem_1 = decoder.get_dem("Z", circuit_level=True) + dem_2 = decoder.get_dem("Z", circuit_level=True) + + assert dem_1 == dem_2 + assert calls == 1 + def test_decode_trivial_syndrome_z(self) -> None: """Decode trivial Z syndrome (no errors).""" patch = SurfacePatch.create(distance=3) @@ -241,6 +299,302 @@ def test_generate_surface_code_dem_x(self) -> None: assert isinstance(dem, str) assert "error" in dem + def test_generate_dem_from_patch_can_skip_stim_decomposition(self) -> None: + """Stim patch DEM helper should support raw vs decomposed DEM output.""" + from pecos.qec.surface.decode import generate_dem_from_patch + + patch = SurfacePatch.create(distance=3) + noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.01, p_prep=0.001) + + full_dem = generate_dem_from_patch(patch, num_rounds=4, noise=noise, basis="X", decompose_errors=False) + decomposed_dem = generate_dem_from_patch(patch, num_rounds=4, noise=noise, basis="X", decompose_errors=True) + + assert "^" not in full_dem + assert "^" in decomposed_dem + + def test_generate_dem_from_tick_circuit_supports_raw_and_decomposed_output(self) -> None: + """Native TickCircuit DEM helper should preserve both public output forms.""" + patch = SurfacePatch.create(distance=3) + tc = generate_tick_circuit_from_patch(patch, num_rounds=4, basis="X") + params = {"p1": 0.001, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.001} + + raw_dem = generate_dem_from_tick_circuit(tc, **params, decompose_errors=False) + decomposed_dem = generate_dem_from_tick_circuit(tc, **params, decompose_errors=True) + + assert raw_dem != decomposed_dem + assert "^" not in raw_dem + assert "^" in decomposed_dem + + def test_native_circuit_level_dem_threads_ancilla_budget(self) -> None: + """Native DEM helpers should use the requested ancilla-budgeted circuit family.""" + from pecos.qec.surface.decode import generate_circuit_level_dem_from_builder + + patch = SurfacePatch.create(distance=3) + noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.01, p_prep=0.001) + params = {"p1": noise.p1, "p2": noise.p2, "p_meas": noise.p_meas, "p_prep": noise.p_prep} + + full_tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="X") + batched_tc = generate_tick_circuit_from_patch( + patch, + num_rounds=2, + basis="X", + ancilla_budget=2, + ) + + full_dem = generate_circuit_level_dem_from_builder(patch, num_rounds=2, noise=noise, basis="X") + batched_dem = generate_circuit_level_dem_from_builder( + patch, + num_rounds=2, + noise=noise, + basis="X", + ancilla_budget=2, + ) + + assert full_dem == generate_dem_from_tick_circuit(full_tc, **params, decompose_errors=False) + assert batched_dem == generate_dem_from_tick_circuit(batched_tc, **params, decompose_errors=False) + assert batched_dem != full_dem + + decoder = SurfaceDecoder( + patch, + num_rounds=2, + noise=noise, + ancilla_budget=2, + circuit_level_dem_mode="native_full", + ) + assert decoder.get_dem("X", circuit_level=True) == batched_dem + + def test_native_circuit_level_dem_cache_respects_patch_geometry(self) -> None: + """Shared native DEM caching should preserve asymmetric patch geometry.""" + from pecos.qec.surface.circuit_builder import generate_dem_from_tick_circuit, generate_tick_circuit_from_patch + from pecos.qec.surface.decode import generate_circuit_level_dem_from_builder + + patch = SurfacePatch.create(dx=3, dz=5) + noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.01, p_prep=0.001) + params = {"p1": noise.p1, "p2": noise.p2, "p_meas": noise.p_meas, "p_prep": noise.p_prep} + + tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="X") + expected_dem = generate_dem_from_tick_circuit(tc, **params, decompose_errors=False) + cached_dem = generate_circuit_level_dem_from_builder( + patch, + num_rounds=2, + noise=noise, + basis="X", + ) + + assert cached_dem == expected_dem + + def test_traced_qis_native_dem_and_sampler_build(self) -> None: + """The traced-QIS circuit source should build DEMs and samplers end-to-end.""" + from pecos.qec.surface import build_native_sampler + from pecos.qec.surface.decode import generate_circuit_level_dem_from_builder + + _require_selene_runtime() + + patch = SurfacePatch.create(distance=3) + noise = NoiseModel(p1=0.001, p2=0.001, p_meas=0.001, p_prep=0.001) + + dem = generate_circuit_level_dem_from_builder( + patch, + num_rounds=2, + noise=noise, + basis="Z", + decompose_errors=True, + circuit_source="traced_qis", + ) + assert "error(" in dem + + sampler = build_native_sampler( + patch, + num_rounds=2, + noise=noise, + basis="Z", + circuit_source="traced_qis", + ) + det_events, obs_flips = sampler.sample(4, seed=7) + assert det_events.shape == (4, sampler.num_detectors) + assert obs_flips.shape == (4, sampler.num_observables) + assert sampler.sampling_model == "dem" + + mnm_sampler = build_native_sampler( + patch, + num_rounds=2, + noise=noise, + basis="Z", + circuit_source="traced_qis", + sampling_model="mnm", + ) + mnm_det_events, mnm_obs_flips = mnm_sampler.sample(4, seed=7) + assert mnm_det_events.shape == (4, mnm_sampler.num_detectors) + assert mnm_obs_flips.shape == (4, mnm_sampler.num_observables) + assert mnm_sampler.sampling_model == "influence_dem" # "mnm" remapped to unified sampler + + influence_sampler = build_native_sampler( + patch, + num_rounds=2, + noise=noise, + basis="Z", + circuit_source="traced_qis", + sampling_model="influence_dem", + ) + influence_det_events, influence_obs_flips = influence_sampler.sample(4, seed=7) + assert influence_det_events.shape == (4, influence_sampler.num_detectors) + assert influence_obs_flips.shape == (4, influence_sampler.num_observables) + assert influence_sampler.sampling_model == "influence_dem" + + decoder = SurfaceDecoder( + patch, + num_rounds=2, + noise=noise, + circuit_level_dem_mode="native_decomposed", + circuit_level_dem_source="traced_qis", + ) + decoder_dem = decoder.get_dem("Z", circuit_level=True) + assert "error(" in decoder_dem + assert decoder_dem.count("detector(") == dem.count("detector(") + assert decoder_dem.count("logical_observable") == dem.count("logical_observable") + + def test_traced_qis_native_dem_matches_stim_dem(self) -> None: + """The traced-QIS PECOS DEM should exactly match the traced-QIS Stim DEM.""" + import re + + stim = pytest.importorskip("stim") + + from pecos.qec.surface.circuit_builder import ( + generate_dem_from_tick_circuit, + tick_circuit_to_stim, + ) + from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model + + _require_selene_runtime() + + def extract_errors(dem_str: str) -> dict[str, float]: + errors: dict[str, float] = {} + for line in dem_str.strip().splitlines(): + match = re.match(r"error\(([^)]+)\)\s*(.*)", line.strip()) + if match: + errors[match.group(2).strip()] = float(match.group(1)) + return errors + + patch = SurfacePatch.create(distance=3) + noise = NoiseModel(p1=0.003, p2=0.003, p_meas=0.003, p_prep=0.003) + + for basis in ("X", "Z"): + tc = _build_surface_tick_circuit_for_native_model( + patch, + num_rounds=6, + basis=basis, + circuit_source="traced_qis", + ) + pecos_dem = generate_dem_from_tick_circuit( + tc, + p1=noise.p1, + p2=noise.p2, + p_meas=noise.p_meas, + p_prep=noise.p_prep, + decompose_errors=False, + ) + stim_dem = str( + stim.Circuit( + tick_circuit_to_stim( + tc, + p1=noise.p1, + p2=noise.p2, + p_meas=noise.p_meas, + p_prep=noise.p_prep, + ), + ).detector_error_model(decompose_errors=False), + ) + + pecos_errors = extract_errors(pecos_dem) + stim_errors = extract_errors(stim_dem) + assert set(pecos_errors) == set(stim_errors) + for target in pecos_errors: + rel_diff = abs(pecos_errors[target] - stim_errors[target]) / max( + pecos_errors[target], + stim_errors[target], + 1e-12, + ) + assert rel_diff < 0.005, ( + f"{basis} traced-QIS DEM mismatch for {target}: " + f"PECOS={pecos_errors[target]:.8f}, Stim={stim_errors[target]:.8f}" + ) + + def test_traced_qis_native_topology_cache_is_shared_across_public_apis(self) -> None: + """Public traced-QIS DEM and sampler helpers should reuse the shared topology cache.""" + from pecos.qec.surface import build_native_sampler + from pecos.qec.surface.decode import ( + _cached_surface_native_dem_string, + _cached_surface_native_topology, + generate_circuit_level_dem_from_builder, + ) + + _require_selene_runtime() + + patch = SurfacePatch.create(distance=3) + noise_a = NoiseModel(p1=0.001, p2=0.001, p_meas=0.001, p_prep=0.001) + noise_b = NoiseModel(p1=0.002, p2=0.002, p_meas=0.002, p_prep=0.002) + + _cached_surface_native_topology.cache_clear() + _cached_surface_native_dem_string.cache_clear() + + generate_circuit_level_dem_from_builder( + patch, + num_rounds=2, + noise=noise_a, + basis="Z", + decompose_errors=True, + circuit_source="traced_qis", + ) + after_dem = _cached_surface_native_topology.cache_info() + after_dem_str = _cached_surface_native_dem_string.cache_info() + assert after_dem.misses == 1 + assert after_dem_str.misses == 1 + + sampler = build_native_sampler( + patch, + num_rounds=2, + noise=noise_a, + basis="Z", + circuit_source="traced_qis", + ) + det_events, obs_flips = sampler.sample(2, seed=11) + assert det_events.shape == (2, sampler.num_detectors) + assert obs_flips.shape == (2, sampler.num_observables) + + after_sampler = _cached_surface_native_topology.cache_info() + after_sampler_dem_str = _cached_surface_native_dem_string.cache_info() + assert after_sampler.misses == after_dem.misses + assert after_sampler.hits >= after_dem.hits + 1 + assert after_sampler_dem_str.misses == after_dem_str.misses + assert after_sampler_dem_str.hits >= after_dem_str.hits + 1 + + build_native_sampler( + patch, + num_rounds=2, + noise=noise_b, + basis="Z", + circuit_source="traced_qis", + ) + after_second_noise = _cached_surface_native_dem_string.cache_info() + assert after_second_noise.misses == after_sampler_dem_str.misses + 1 + + def test_generate_dem_from_tick_circuit_maximal_decomposition_prefers_singletons(self) -> None: + """Maximal decomposition should no longer be a no-op.""" + patch = SurfacePatch.create(distance=3) + tc = generate_tick_circuit_from_patch(patch, num_rounds=20, basis="X") + params = {"p1": 0.0, "p2": 0.00235, "p_meas": 0.01972626855445279, "p_prep": 0.0010045162906914633} + + decomposed_dem = generate_dem_from_tick_circuit(tc, **params, decompose_errors=True) + maximal_dem = generate_dem_from_tick_circuit( + tc, + **params, + decompose_errors=False, + maximal_decomposition=True, + ) + + assert maximal_dem != decomposed_dem + assert _count_singleton_error_parts(maximal_dem) > _count_singleton_error_parts(decomposed_dem) + def test_dem_detector_count(self) -> None: """DEM should have correct number of detectors.""" patch = SurfacePatch.create(distance=3) @@ -273,25 +627,15 @@ def test_dem_single_round(self) -> None: class TestNoisySimulation: - """Integration tests for noisy simulation (requires selene_sim).""" - - @pytest.fixture - def check_selene(self) -> bool | None: - """Check if selene_sim is available.""" - try: - import selene_sim - - return True - except ImportError: - pytest.skip("selene_sim not available") - return False - - def test_run_noisy_memory_experiment_import( - self, - check_selene: bool, - ) -> None: + """Integration tests for noisy simulation. + + The Selene runtime and the ``selene_sim`` Python package are expected to be + installed in every environment that runs this test tree. A missing runtime + now raises rather than being silently skipped (see ``_require_selene_runtime``). + """ + + def test_run_noisy_memory_experiment_import(self) -> None: """Test that run_noisy_memory_experiment can be imported.""" - _ = check_selene # Fixture triggers skip if unavailable from pecos.qec.surface import run_noisy_memory_experiment assert callable(run_noisy_memory_experiment) @@ -317,9 +661,8 @@ def test_simulation_result_dataclass(self) -> None: assert result.num_shots == 100 assert result.logical_error_rate == 0.05 - def test_noiseless_simulation(self, check_selene: bool) -> None: + def test_noiseless_simulation(self) -> None: """Noiseless simulation should have zero logical error rate.""" - _ = check_selene # Fixture triggers skip if unavailable from pecos.compilation_pipeline import compile_guppy_to_hugr from pecos.guppy.surface import get_num_qubits, make_surface_code from pecos.qec.surface import SurfacePatch diff --git a/python/quantum-pecos/tests/qec/surface/test_surface_geometry.py b/python/quantum-pecos/tests/qec/surface/test_surface_geometry.py new file mode 100644 index 000000000..c09b21978 --- /dev/null +++ b/python/quantum-pecos/tests/qec/surface/test_surface_geometry.py @@ -0,0 +1,315 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Tests for surface code geometry across all dimensions. + +Verifies that the stabilizer generators, code parameters, CNOT scheduling, +and circuit generation work correctly for: +- Standard odd square codes (d=3,5,7) +- Even square codes (d=2,4) +- Asymmetric codes (dx != dz) +- Repetition codes (dx=1 or dz=1) +- Single qubit (dx=dz=1) +""" + +import pytest +from pecos.qec.surface import SurfacePatch +from pecos.qec.surface.schedule import compute_cnot_schedule + + +# ============================================================ +# Code parameters: n, k, d +# ============================================================ + + +@pytest.mark.parametrize( + ("dx", "dz", "expected_n", "expected_k", "expected_d"), + [ + # Single qubit + (1, 1, 1, 1, 1), + # Repetition codes (X checks) + (1, 3, 3, 1, 1), + (1, 5, 5, 1, 1), + (1, 7, 7, 1, 1), + # Repetition codes (Z checks) + (3, 1, 3, 1, 1), + (5, 1, 5, 1, 1), + # Even square + (2, 2, 4, 1, 2), + (4, 4, 16, 1, 4), + # Odd square (standard surface code) + (3, 3, 9, 1, 3), + (5, 5, 25, 1, 5), + (7, 7, 49, 1, 7), + # Asymmetric + (2, 3, 6, 1, 2), + (3, 2, 6, 1, 2), + (3, 5, 15, 1, 3), + (5, 3, 15, 1, 3), + (2, 5, 10, 1, 2), + ], +) +def test_code_parameters(dx, dz, expected_n, expected_k, expected_d): + """Code parameters [[n,k,d]] should be correct for all dimensions.""" + patch = SurfacePatch.create(dx=dx, dz=dz) + n = patch.num_data + k = n - patch.geometry.num_x_stab - patch.geometry.num_z_stab + d = patch.distance + + assert n == expected_n + assert k == expected_k + assert d == expected_d + + +# ============================================================ +# Stabilizer structure +# ============================================================ + + +@pytest.mark.parametrize( + ("dx", "dz", "expected_x", "expected_z"), + [ + (1, 1, 0, 0), + (1, 3, 2, 0), + (3, 1, 0, 2), + (1, 5, 4, 0), + (5, 1, 0, 4), + (2, 2, 2, 1), + (3, 3, 4, 4), + (2, 3, 3, 2), + (3, 2, 2, 3), + (4, 4, 8, 7), + (5, 5, 12, 12), + ], +) +def test_stabilizer_counts(dx, dz, expected_x, expected_z): + """Number of X and Z stabilizers should match expected values.""" + patch = SurfacePatch.create(dx=dx, dz=dz) + assert patch.geometry.num_x_stab == expected_x + assert patch.geometry.num_z_stab == expected_z + + +def test_repetition_code_x_checks(): + """dx=1 repetition code should have only X stabilizers (adjacent XX pairs).""" + patch = SurfacePatch.create(dx=1, dz=5) + assert patch.geometry.num_z_stab == 0 + qubits = [s.data_qubits for s in patch.geometry.x_stabilizers] + # All should be adjacent pairs covering 0..4 + for q1, q2 in qubits: + assert q2 == q1 + 1 + + +def test_repetition_code_z_checks(): + """dz=1 repetition code should have only Z stabilizers (adjacent ZZ pairs).""" + patch = SurfacePatch.create(dx=5, dz=1) + assert patch.geometry.num_x_stab == 0 + qubits = [s.data_qubits for s in patch.geometry.z_stabilizers] + for q1, q2 in qubits: + assert q2 == q1 + 1 + + +def test_all_data_qubits_in_stabilizer_support(): + """Every data qubit (except logical operator edges) should appear in at least one stabilizer.""" + for dx, dz in [(3, 3), (2, 3), (3, 2), (2, 2), (4, 4)]: + patch = SurfacePatch.create(dx=dx, dz=dz) + touched = set() + for s in patch.geometry.x_stabilizers: + touched.update(s.data_qubits) + for s in patch.geometry.z_stabilizers: + touched.update(s.data_qubits) + assert touched == set(range(patch.num_data)), f"Untouched qubits in {dx}x{dz}" + + +def test_stabilizer_weights(): + """Bulk stabilizers should be weight 4, boundary weight 2.""" + for dx, dz in [(3, 3), (5, 5), (2, 3), (3, 5)]: + patch = SurfacePatch.create(dx=dx, dz=dz) + for s in list(patch.geometry.x_stabilizers) + list(patch.geometry.z_stabilizers): + if s.is_boundary: + assert len(s.data_qubits) == 2, f"Boundary stab has weight {len(s.data_qubits)}" + else: + assert len(s.data_qubits) == 4, f"Bulk stab has weight {len(s.data_qubits)}" + + +# ============================================================ +# Logical operators +# ============================================================ + + +def test_logical_x_weight_equals_dx(): + """Logical X should have weight dx (left edge of the grid).""" + for dx, dz in [(3, 3), (3, 5), (5, 3), (2, 3), (1, 5)]: + patch = SurfacePatch.create(dx=dx, dz=dz) + assert len(patch.geometry.logical_x.data_qubits) == dx + + +def test_logical_z_weight_equals_dz(): + """Logical Z should have weight dz (top edge of the grid).""" + for dx, dz in [(3, 3), (3, 5), (5, 3), (2, 3), (1, 5)]: + patch = SurfacePatch.create(dx=dx, dz=dz) + assert len(patch.geometry.logical_z.data_qubits) == dz + + +def test_logical_x_is_left_edge(): + """Logical X qubits should be column 0 of the dx x dz grid.""" + for dx, dz in [(3, 3), (3, 5), (2, 3)]: + patch = SurfacePatch.create(dx=dx, dz=dz) + expected = tuple(i * dz for i in range(dx)) + assert patch.geometry.logical_x.data_qubits == expected + + +def test_logical_z_is_top_edge(): + """Logical Z qubits should be row 0 of the dx x dz grid.""" + for dx, dz in [(3, 3), (3, 5), (2, 3)]: + patch = SurfacePatch.create(dx=dx, dz=dz) + expected = tuple(range(dz)) + assert patch.geometry.logical_z.data_qubits == expected + + +# ============================================================ +# CNOT schedule: no conflicts +# ============================================================ + + +@pytest.mark.parametrize( + ("dx", "dz"), + [ + (1, 3), (3, 1), + (2, 2), (2, 3), (3, 2), + (3, 3), (3, 5), (5, 3), + (4, 4), (5, 5), + ], +) +def test_cnot_schedule_no_conflicts(dx, dz): + """No data qubit should be touched twice in the same CNOT round.""" + patch = SurfacePatch.create(dx=dx, dz=dz) + schedule = compute_cnot_schedule(patch) + for rnd_idx, rnd in enumerate(schedule): + data_qubits = [dq for _, _, dq in rnd] + assert len(data_qubits) == len(set(data_qubits)), ( + f"{dx}x{dz} round {rnd_idx}: data qubit collision {data_qubits}" + ) + + +# ============================================================ +# Backward compatibility: square odd codes unchanged +# ============================================================ + + +def test_square_odd_codes_match_original(): + """The generalized generators should produce identical results to the + original single-d generators for square odd codes.""" + from pecos.qec.surface.layouts.rotated_lattice import ( + compute_rotated_x_stabilizers, + compute_rotated_z_stabilizers, + get_rotated_logical_x, + get_rotated_logical_z, + ) + + for d in [3, 5, 7]: + x_single = compute_rotated_x_stabilizers(d) + x_pair = compute_rotated_x_stabilizers(d, d) + z_single = compute_rotated_z_stabilizers(d) + z_pair = compute_rotated_z_stabilizers(d, d) + + assert len(x_single) == len(x_pair) + assert len(z_single) == len(z_pair) + + for a, b in zip(x_single, x_pair): + assert a.data_qubits == b.data_qubits + assert a.is_boundary == b.is_boundary + + for a, b in zip(z_single, z_pair): + assert a.data_qubits == b.data_qubits + assert a.is_boundary == b.is_boundary + + assert get_rotated_logical_x(d) == get_rotated_logical_x(d, d) + assert get_rotated_logical_z(d) == get_rotated_logical_z(d, d) + + +# ============================================================ +# Transposition symmetry +# ============================================================ + + +def test_transpose_swaps_x_and_z_counts(): + """Swapping dx and dz should swap the number of X and Z stabilizers.""" + for dx, dz in [(2, 3), (3, 5), (2, 5), (1, 3), (1, 5)]: + p1 = SurfacePatch.create(dx=dx, dz=dz) + p2 = SurfacePatch.create(dx=dz, dz=dx) + assert p1.geometry.num_x_stab == p2.geometry.num_z_stab + assert p1.geometry.num_z_stab == p2.geometry.num_x_stab + + +# ============================================================ +# Circuit generation +# ============================================================ + + +@pytest.mark.parametrize( + ("dx", "dz"), + [ + (1, 1), (1, 3), (3, 1), + (2, 2), (2, 3), (3, 2), + (3, 3), + ], +) +def test_circuit_generation(dx, dz): + """LogicalCircuitBuilder should produce a valid TickCircuit for all dimensions.""" + from pecos.qec.surface import LogicalCircuitBuilder + + patch = SurfacePatch.create(dx=dx, dz=dz) + lcb = LogicalCircuitBuilder() + lcb.add_patch(patch, "A") + basis = "Z" if dx >= dz else "X" + lcb.add_memory("A", rounds=2, basis=basis) + tc = lcb.to_tick_circuit() + + assert tc.num_ticks() > 0 + assert tc.gate_count() > 0 + + +# ============================================================ +# Transversal gate square check +# ============================================================ + + +def test_transversal_h_rejects_nonsquare(): + """Transversal H should reject non-square patches.""" + from pecos.qec.surface import LogicalCircuitBuilder + + patch = SurfacePatch.create(dx=2, dz=3) + lcb = LogicalCircuitBuilder() + lcb.add_patch(patch, "A") + with pytest.raises(ValueError, match="square"): + lcb.add_transversal_h("A") + + +def test_transversal_h_accepts_square(): + """Transversal H should accept square patches of any distance.""" + from pecos.qec.surface import LogicalCircuitBuilder + + for d in [2, 3, 4, 5]: + patch = SurfacePatch.create(distance=d) + lcb = LogicalCircuitBuilder() + lcb.add_patch(patch, "A") + lcb.add_memory("A", rounds=1, basis="Z") + lcb.add_transversal_h("A") + lcb.add_memory("A", rounds=1, basis="X") + + +# ============================================================ +# Validation +# ============================================================ + + +def test_distance_zero_rejected(): + """Distance 0 should raise ValueError.""" + with pytest.raises(ValueError): + SurfacePatch.create(distance=0) + + +def test_negative_distance_rejected(): + """Negative distance should raise ValueError.""" + with pytest.raises(ValueError): + SurfacePatch.create(dx=-1, dz=3) diff --git a/python/quantum-pecos/tests/qec/surface/test_surface_metadata.py b/python/quantum-pecos/tests/qec/surface/test_surface_metadata.py new file mode 100644 index 000000000..077110f7f --- /dev/null +++ b/python/quantum-pecos/tests/qec/surface/test_surface_metadata.py @@ -0,0 +1,305 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Tests for the public surface metadata helpers. + +These tests cover the public descriptor API exposed for surface-code memory +experiments, independent of the DEM decomposition internals. +""" + +import json +from typing import TYPE_CHECKING + +import pytest +from pecos.qec.surface import ( + SurfacePatch, + classify_stabilizer_boundary, + describe_surface_memory_experiment, + generate_tick_circuit_from_patch, + get_detector_descriptors_from_tick_circuit, + get_measurement_order_from_tick_circuit, + get_observable_descriptors_from_tick_circuit, + get_stab_schedule, + get_stabilizer_region, + get_stabilizer_schedule_entries, + get_stabilizer_schedule_metadata, + get_stabilizer_touch_label, +) + +if TYPE_CHECKING: + from pecos.qec.surface import SurfacePatchDescriptor + + +def test_surface_schedule_helpers_expose_region_and_touch_labels() -> None: + """Surface metadata helpers should expose stable boundary and touch labels.""" + patch = SurfacePatch.create(distance=3) + + x_top = patch.x_stabilizers[0] + x_bulk = patch.x_stabilizers[1] + z_left = patch.z_stabilizers[0] + + assert classify_stabilizer_boundary("X", x_top.data_qubits, patch.distance) == "top" + assert classify_stabilizer_boundary("Z", z_left.data_qubits, patch.distance) == "left" + + assert get_stabilizer_region(x_top, patch) == "top+left" + assert get_stabilizer_region(x_bulk, patch) == "top+right" + assert get_stabilizer_region(z_left, patch) == "bottom+left" + + assert get_stabilizer_touch_label(x_top, patch, 0) == "left" + assert get_stabilizer_touch_label(x_top, patch, 1) == "right" + assert get_stabilizer_touch_label(z_left, patch, 3) == "top" + assert get_stabilizer_touch_label(z_left, patch, 6) == "bottom" + assert get_stabilizer_touch_label(x_bulk, patch, 1) == "TL" + assert get_stabilizer_touch_label(x_bulk, patch, 2) == "TR" + assert get_stabilizer_touch_label(x_bulk, patch, 4) == "BL" + assert get_stabilizer_touch_label(x_bulk, patch, 5) == "BR" + + assert get_stab_schedule("X", x_top.data_qubits, x_top.is_boundary, patch.dx, patch.dz) == [(2, 1), (3, 0)] + assert get_stab_schedule("Z", z_left.data_qubits, z_left.is_boundary, patch.dx, patch.dz) == [(0, 3), (1, 6)] + + assert get_stabilizer_schedule_entries(x_top, patch) == [ + {"round_0based": 2, "data_qubit": 1, "touch_label": "right"}, + {"round_0based": 3, "data_qubit": 0, "touch_label": "left"}, + ] + assert get_stabilizer_schedule_entries(z_left, patch) == [ + {"round_0based": 0, "data_qubit": 3, "touch_label": "top"}, + {"round_0based": 1, "data_qubit": 6, "touch_label": "bottom"}, + ] + + x_top_meta = get_stabilizer_schedule_metadata(x_top, patch) + assert x_top_meta["stabilizer_kind"] == "X" + assert x_top_meta["stabilizer_index"] == 0 + assert x_top_meta["stabilizer_is_boundary"] is True + assert x_top_meta["stabilizer_region"] == "top+left" + assert x_top_meta["schedule_rounds"] == [2, 3] + assert x_top_meta["schedule_start_round"] == 2 + assert x_top_meta["schedule_end_round"] == 3 + assert x_top_meta["schedule_entries"] == get_stabilizer_schedule_entries(x_top, patch) + + +def test_surface_patch_exposes_stabilizer_descriptors() -> None: + """Surface patches should publish detailed stabilizer descriptors.""" + patch = SurfacePatch.create(distance=3) + + x0 = patch.get_stabilizer_descriptor("X", 0) + assert x0["stabilizer_kind"] == "X" + assert x0["stabilizer_index"] == 0 + assert x0["stabilizer_region"] == "top+left" + assert x0["data_qubits"] == [0, 1] + assert x0["data_qubit_positions"] == [[0, 0], [0, 1]] + assert x0["weight"] == 2 + assert x0["schedule_rounds"] == [2, 3] + assert x0["schedule_entries"] == [ + {"round_0based": 2, "data_qubit": 1, "touch_label": "right"}, + {"round_0based": 3, "data_qubit": 0, "touch_label": "left"}, + ] + + x_descriptors = list(patch.iter_stabilizer_descriptors("X")) + z_descriptors = list(patch.iter_stabilizer_descriptors("Z")) + all_descriptors = list(patch.iter_stabilizer_descriptors()) + + assert len(x_descriptors) == len(patch.x_stabilizers) + assert len(z_descriptors) == len(patch.z_stabilizers) + assert len(all_descriptors) == len(patch.x_stabilizers) + len(patch.z_stabilizers) + assert all(row["stabilizer_kind"] == "X" for row in x_descriptors) + assert all(row["stabilizer_kind"] == "Z" for row in z_descriptors) + + +def test_surface_patch_exposes_patch_descriptor() -> None: + """Surface patches should expose a compact patch descriptor.""" + patch = SurfacePatch.create(distance=3) + + descriptor: SurfacePatchDescriptor = patch.get_patch_descriptor() + assert descriptor == { + "distance": 3, + "dx": 3, + "dz": 3, + "rotated": True, + "orientation": "X_TOP_BOTTOM", + "num_data": 9, + "num_ancilla": 8, + "num_qubits": 17, + } + + +def test_surface_patch_exposes_logical_descriptors() -> None: + """Surface patches should expose public logical support descriptors.""" + patch = SurfacePatch.create(distance=3) + + logical_x = patch.get_logical_descriptor("X") + logical_z = patch.get_logical_descriptor("Z") + logicals = list(patch.iter_logical_descriptors()) + + assert logical_x["logical_type"] == "X" + assert logical_x["data_qubits"] == list(patch.geometry.logical_x.data_qubits) + assert logical_x["data_qubit_positions"] == [[0, 0], [1, 0], [2, 0]] + assert logical_x["weight"] == len(patch.geometry.logical_x.data_qubits) + assert logical_x["support_axis"] == "vertical" + + assert logical_z["logical_type"] == "Z" + assert logical_z["data_qubits"] == list(patch.geometry.logical_z.data_qubits) + assert logical_z["data_qubit_positions"] == [[0, 0], [0, 1], [0, 2]] + assert logical_z["weight"] == len(patch.geometry.logical_z.data_qubits) + assert logical_z["support_axis"] == "horizontal" + + assert logicals == [logical_x, logical_z] + + +def test_tick_circuit_exposes_detector_descriptors() -> None: + """Tick circuits should publish detector descriptors consistent with cached metadata.""" + patch = SurfacePatch.create(distance=3) + tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="X") + + descriptors = get_detector_descriptors_from_tick_circuit(tc, patch) + cached = json.loads(tc.get_meta("detector_descriptors") or "[]") + + assert descriptors == cached + assert len(descriptors) == int(tc.get_meta("num_detectors") or "0") + + first_x = next( + row + for row in descriptors + if row["stabilizer_kind"] == "X" and row["stabilizer_index"] == 0 and row["round"] == 0 + ) + assert first_x["coords"] == [0, 0, 0] + assert first_x["stabilizer_region"] == "top+left" + assert first_x["stabilizer_is_boundary"] is True + assert first_x["data_qubits"] == [0, 1] + assert first_x["data_qubit_positions"] == [[0, 0], [0, 1]] + assert first_x["schedule_rounds"] == [2, 3] + assert first_x["is_final_round"] is False + + final_x = next( + row + for row in descriptors + if row["stabilizer_kind"] == "X" and row["stabilizer_index"] == 0 and row["is_final_round"] + ) + assert final_x["round"] == 2 + assert final_x["coords"] == [0, 0, 2] + + +def test_tick_circuit_exposes_observable_descriptors() -> None: + """Tick circuits should publish observable descriptors derived from logical metadata.""" + patch = SurfacePatch.create(distance=3) + tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="X") + + descriptors = get_observable_descriptors_from_tick_circuit(tc, patch) + cached = json.loads(tc.get_meta("observable_descriptors") or "[]") + logical_x = patch.get_logical_descriptor("X") + + assert descriptors == cached + assert len(descriptors) == 1 + + row = descriptors[0] + assert row["observable_id"] == 0 + assert row["basis"] == "X" + assert row["records"] == cached[0]["records"] + for key in logical_x: + assert row[key] == logical_x[key] + + +def test_tick_circuit_exposes_measurement_order() -> None: + """Tick circuits should expose measurement order matching their MZ gates.""" + patch = SurfacePatch.create(distance=3) + tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="X") + + observed = get_measurement_order_from_tick_circuit(tc) + + expected: list[int] = [] + for tick_index in range(tc.num_ticks()): + tick = tc.get_tick(tick_index) + if tick is None: + continue + for gate in tick.gates(): + if "MZ" not in str(gate.gate_type): + continue + for qubit in gate.qubits: + if hasattr(qubit, "index"): + expected.append(qubit.index()) + else: + expected.append(int(qubit)) + + assert observed == expected + assert len(observed) == int(tc.get_meta("num_measurements") or "0") + + +def test_tick_circuit_respects_ancilla_budget_in_measurement_order() -> None: + """Measurement ordering should reflect ancilla reuse when a budget is imposed.""" + patch = SurfacePatch.create(distance=3) + full_tc = generate_tick_circuit_from_patch(patch, num_rounds=1, basis="Z") + batched_tc = generate_tick_circuit_from_patch( + patch, + num_rounds=1, + basis="Z", + ancilla_budget=2, + ) + + full_order = get_measurement_order_from_tick_circuit(full_tc) + batched_order = get_measurement_order_from_tick_circuit(batched_tc) + num_ancilla = patch.geometry.num_ancilla + + full_ancilla_measures = full_order[:num_ancilla] + batched_ancilla_measures = batched_order[:num_ancilla] + + assert len(set(full_ancilla_measures)) == num_ancilla + assert len(set(batched_ancilla_measures)) == 2 + assert max(batched_ancilla_measures) == patch.num_data + 1 + assert batched_tc.get_meta("ancilla_budget") == "2" + assert full_tc.get_meta("num_detectors") == batched_tc.get_meta("num_detectors") + assert full_tc.get_meta("num_measurements") == batched_tc.get_meta("num_measurements") + + +@pytest.mark.parametrize( + ("patch_kwargs", "basis"), + [ + ({"distance": 3, "rotated": False}, "Z"), + ({"distance": 5, "rotated": False}, "X"), + ({"dx": 3, "dz": 5}, "X"), + ({"dx": 5, "dz": 3}, "Z"), + ], +) +def test_surface_metadata_helpers_support_nonrotated_and_asymmetric_patches( + patch_kwargs: dict[str, object], + basis: str, +) -> None: + """Surface metadata helpers should also work on non-rotated and asymmetric patches.""" + patch = SurfacePatch.create(**patch_kwargs) + summary = describe_surface_memory_experiment(patch, num_rounds=1, basis=basis) + + assert summary["patch"]["rotated"] == patch.rotated + assert summary["patch"]["dx"] == patch.dx + assert summary["patch"]["dz"] == patch.dz + assert summary["basis"] == basis + assert summary["num_rounds"] == 1 + assert summary["x_stabilizers"] + assert summary["z_stabilizers"] + assert summary["logicals"] + assert summary["detectors"] + assert summary["observables"] + + +def test_describe_surface_memory_experiment_returns_descriptor_bundle() -> None: + """Experiment summaries should bundle patch, stabilizer, detector, and observable metadata.""" + patch = SurfacePatch.create(distance=3) + tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="X") + summary = describe_surface_memory_experiment(patch, num_rounds=2, basis="X") + + assert summary["patch"] == { + "distance": 3, + "dx": 3, + "dz": 3, + "rotated": True, + "orientation": "X_TOP_BOTTOM", + "num_data": 9, + "num_ancilla": 8, + "num_qubits": 17, + } + assert summary["basis"] == "X" + assert summary["num_rounds"] == 2 + assert summary["ancilla_budget"] is None + assert len(summary["x_stabilizers"]) == len(patch.x_stabilizers) + assert len(summary["z_stabilizers"]) == len(patch.z_stabilizers) + assert summary["stabilizers"] == summary["x_stabilizers"] + summary["z_stabilizers"] + assert summary["logicals"] == list(patch.iter_logical_descriptors()) + assert summary["detectors"] == get_detector_descriptors_from_tick_circuit(tc, patch) + assert summary["observables"] == get_observable_descriptors_from_tick_circuit(tc, patch) diff --git a/python/quantum-pecos/tests/qec/test_analysis_meas_sampling.py b/python/quantum-pecos/tests/qec/test_analysis_meas_sampling.py new file mode 100644 index 000000000..7fcc7b1fd --- /dev/null +++ b/python/quantum-pecos/tests/qec/test_analysis_meas_sampling.py @@ -0,0 +1,125 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Tests for analysis helpers with DEM-backed sampling backends.""" + +import pytest + +from pecos.qec.analysis import empirical_correlation_table, fit_dem_from_simulation +from pecos.qec.surface import SurfacePatch +from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model +from pecos_rslib_exp import depolarizing + + +@pytest.fixture +def d3_circuit_and_noise(): + patch = SurfacePatch.create(distance=3) + tc = _build_surface_tick_circuit_for_native_model(patch, 6, "Z", circuit_source="abstract") + noise = depolarizing().p1(0.005).p2(0.005).p_meas(0.005).p_prep(0.005) + return tc, noise + + +class TestEmpiricalCorrelationTable: + def test_dem_sampling_returns_nonempty(self, d3_circuit_and_noise): + tc, noise = d3_circuit_and_noise + table = empirical_correlation_table( + tc, + noise, + shots=5000, + max_order=1, + backend="dem_sampling", + seed=42, + ) + assert len(table) > 0, "Should return at least one rate entry" + + def test_meas_sampling_returns_nonempty(self, d3_circuit_and_noise): + tc, noise = d3_circuit_and_noise + table = empirical_correlation_table( + tc, noise, shots=5000, max_order=1, backend="meas_sampling", seed=42 + ) + assert len(table) > 0, "Should return at least one rate entry" + + def test_meas_sampling_label_shape(self, d3_circuit_and_noise): + tc, noise = d3_circuit_and_noise + table = empirical_correlation_table( + tc, noise, shots=5000, max_order=1, backend="meas_sampling", seed=42 + ) + # Each entry is (detector_indices_tuple, probability) + for indices, prob in table: + assert isinstance(indices, tuple) + assert len(indices) >= 1 + assert isinstance(prob, float) + assert 0.0 <= prob <= 1.0 + + def test_meas_sampling_rates_close_to_stabilizer(self, d3_circuit_and_noise): + tc, noise = d3_circuit_and_noise + shots = 20000 + + meas_table = empirical_correlation_table( + tc, noise, shots=shots, max_order=1, backend="meas_sampling", seed=42 + ) + stab_table = empirical_correlation_table( + tc, noise, shots=shots, max_order=1, backend="stabilizer", seed=42 + ) + + # Both should have the same entries (same detectors) + meas_dict = dict(meas_table) + stab_dict = dict(stab_table) + + assert set(meas_dict.keys()) == set(stab_dict.keys()), ( + "Same detector indices should appear in both" + ) + + # Rates should be statistically close (within 20% relative for active detectors) + close_count = 0 + active_count = 0 + for key in meas_dict: + s = stab_dict[key] + d = meas_dict[key] + if s > 0.005: + active_count += 1 + if abs(d - s) / s < 0.20: + close_count += 1 + + assert active_count > 0, "Should have active detectors" + assert close_count >= active_count * 0.8, ( + f"Only {close_count}/{active_count} rates within 20% of stabilizer" + ) + + +class TestFitDemFromSimulation: + def test_dem_sampling_returns_dem_string(self, d3_circuit_and_noise): + tc, noise = d3_circuit_and_noise + dem_str = fit_dem_from_simulation( + tc, noise, shots=10000, backend="dem_sampling", seed=42 + ) + assert isinstance(dem_str, str) + assert "error(" in dem_str, "DEM string should contain error(...) lines" + + def test_meas_sampling_returns_dem_string(self, d3_circuit_and_noise): + tc, noise = d3_circuit_and_noise + dem_str = fit_dem_from_simulation( + tc, noise, shots=10000, backend="meas_sampling", seed=42 + ) + assert isinstance(dem_str, str) + assert "error(" in dem_str, "DEM string should contain error(...) lines" + + def test_meas_sampling_has_multiple_mechanisms(self, d3_circuit_and_noise): + tc, noise = d3_circuit_and_noise + dem_str = fit_dem_from_simulation( + tc, noise, shots=10000, backend="meas_sampling", seed=42 + ) + error_lines = [l for l in dem_str.strip().split("\n") if l.strip().startswith("error(")] + assert len(error_lines) > 10, f"Expected many mechanisms, got {len(error_lines)}" + + +class TestInvalidBackend: + def test_empirical_correlation_table_rejects_unknown(self, d3_circuit_and_noise): + tc, noise = d3_circuit_and_noise + with pytest.raises(ValueError, match="Unknown backend.*'bogus'"): + empirical_correlation_table(tc, noise, shots=10, backend="bogus") + + def test_fit_dem_from_simulation_rejects_unknown(self, d3_circuit_and_noise): + tc, noise = d3_circuit_and_noise + with pytest.raises(ValueError, match="Unknown backend.*'nope'"): + fit_dem_from_simulation(tc, noise, shots=10, backend="nope") diff --git a/python/quantum-pecos/tests/qec/test_decomposed_dem_invariants.py b/python/quantum-pecos/tests/qec/test_decomposed_dem_invariants.py new file mode 100644 index 000000000..11f2e90ad --- /dev/null +++ b/python/quantum-pecos/tests/qec/test_decomposed_dem_invariants.py @@ -0,0 +1,741 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Invariant checks for PECOS native decomposed DEM output. + +These tests focus on algorithmic correctness of the decomposition itself: +- every decomposed component emitted for MWPM is graphlike +- XOR of decomposed components maps back to an effect present in the full DEM +- representative graphlike L0 singleton edges match Stim's decomposition +""" + +import json +import re +from functools import cache, lru_cache + +import pytest + +stim = pytest.importorskip("stim") + +DIRECT_SOURCE_TYPES = {"Direct", "DirectOneSidedComponent"} +FAST_DISTANCE = pytest.param(3, id="3") +SLOW_DISTANCE = pytest.param(9, marks=pytest.mark.slow, id="9") + + +def parse_dem_with_decomposed( + dem_str: str, +) -> tuple[set[tuple[tuple[int, ...], tuple[int, ...]]], list[list[tuple[tuple[int, ...], tuple[int, ...]]]]]: + """Parse direct and decomposed error targets from a DEM string.""" + direct_targets: set[tuple[tuple[int, ...], tuple[int, ...]]] = set() + decomposed_targets: list[list[tuple[tuple[int, ...], tuple[int, ...]]]] = [] + + for raw_line in dem_str.strip().split("\n"): + line = raw_line.strip() + if not line.startswith("error("): + continue + + match = re.match(r"error\(([^)]+)\)\s+(.*)", line) + if not match: + continue + + rest = match.group(2) + parts = [part.strip() for part in rest.split("^")] + parsed_parts = [] + for part in parts: + dets = tuple(sorted(int(m.group(1)) for m in re.finditer(r"D(\d+)", part))) + logs = tuple(sorted(int(m.group(1)) for m in re.finditer(r"L(\d+)", part))) + parsed_parts.append((dets, logs)) + + if len(parsed_parts) == 1: + direct_targets.add(parsed_parts[0]) + else: + decomposed_targets.append(parsed_parts) + + return direct_targets, decomposed_targets + + +def xor_targets(parts: list[tuple[tuple[int, ...], tuple[int, ...]]]) -> tuple[tuple[int, ...], tuple[int, ...]]: + """XOR a decomposed list of detector/DEM-output observables into one combined effect.""" + dets: set[int] = set() + logs: set[int] = set() + for part_dets, part_logs in parts: + for det in part_dets: + if det in dets: + dets.remove(det) + else: + dets.add(det) + for log in part_logs: + if log in logs: + logs.remove(log) + else: + logs.add(log) + return tuple(sorted(dets)), tuple(sorted(logs)) + + +def detector_union(parts: list[tuple[tuple[int, ...], tuple[int, ...]]]) -> set[int]: + """Return the union of detector ids touched by a decomposed effect.""" + out: set[int] = set() + for dets, _logs in parts: + out.update(dets) + return out + + +def singleton_l0_edges(direct_targets: set[tuple[tuple[int, ...], tuple[int, ...]]]) -> set[int]: + """Collect singleton detector edges that also flip logical L0.""" + return {dets[0] for dets, logs in direct_targets if len(dets) == 1 and len(logs) == 1} + + +def xor_lists(left: list[int], right: list[int]) -> list[int]: + """XOR two integer lists interpreted as parity sets.""" + out = set(left) + for value in right: + if value in out: + out.remove(value) + else: + out.add(value) + return sorted(out) + + +def xor_effect_rows(left: dict[str, list[int]], right: dict[str, list[int]]) -> tuple[list[int], list[int]]: + """XOR two structured detector/DEM-output rows.""" + return ( + xor_lists(left["detectors"], right["detectors"]), + xor_lists(left["dem_outputs"], right["dem_outputs"]), + ) + + +def parse_dem_error_probabilities(dem_str: str) -> dict[str, float]: + """Map DEM target strings to their stated error probabilities.""" + out: dict[str, float] = {} + for raw_line in dem_str.strip().split("\n"): + line = raw_line.strip() + if not line.startswith("error("): + continue + match = re.match(r"error\(([^)]+)\)\s+(.*)", line) + if not match: + continue + out[match.group(2).strip()] = float(match.group(1)) + return out + + +def combine_independent_probs(left: float, right: float) -> float: + """Combine independent error probabilities landing on the same rendered term.""" + return left + right - left * right + + +def combine_xor_probs(left: float, right: float) -> float: + """Combine probabilities for XOR-composed contributions.""" + return left * (1.0 - right) + right * (1.0 - left) + + +@cache +def build_source_tracked_dem(distance: int, basis: str, rounds: int = 20) -> object: + """Build and cache a source-tracked native DEM for one surface-code shape.""" + from pecos.qec import DagFaultAnalyzer, DemBuilder + from pecos.qec.surface import ( + NoiseModel, + SurfacePatch, + generate_tick_circuit_from_patch, + get_measurement_order_from_tick_circuit, + ) + + patch = SurfacePatch.create(distance=distance) + tc = generate_tick_circuit_from_patch(patch, num_rounds=rounds, basis=basis) + dag = tc.to_dag_circuit() + analyzer = DagFaultAnalyzer(dag) + influence_map = analyzer.build_influence_map() + noise = NoiseModel(p1=0.01, p2=0.01, p_meas=0.01, p_prep=0.01) + + builder = DemBuilder(influence_map) + builder.with_noise(noise.p1, noise.p2, noise.p_meas, noise.p_prep) + builder.with_num_measurements(int(tc.get_meta("num_measurements") or "0")) + builder.with_measurement_order(get_measurement_order_from_tick_circuit(tc)) + builder.with_detectors_json(tc.get_meta("detectors")) + observables_json = tc.get_meta("observables") + if observables_json: + builder.with_observables_json(observables_json) + return builder.build() + + +def test_dem_builder_accepts_public_surface_descriptor_json() -> None: + """Public surface descriptor JSON should reproduce the legacy builder output.""" + from pecos.qec import DagFaultAnalyzer, DemBuilder + from pecos.qec.surface import ( + NoiseModel, + SurfacePatch, + generate_tick_circuit_from_patch, + get_detector_descriptors_from_tick_circuit, + get_measurement_order_from_tick_circuit, + get_observable_descriptors_from_tick_circuit, + ) + + patch = SurfacePatch.create(distance=3) + tc = generate_tick_circuit_from_patch(patch, num_rounds=4, basis="X") + dag = tc.to_dag_circuit() + influence_map = DagFaultAnalyzer(dag).build_influence_map() + noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.01, p_prep=0.001) + + def _build(detectors_json: str, observables_json: str | None) -> object: + """Build one source-tracked DEM from serialized detector metadata.""" + builder = DemBuilder(influence_map) + builder.with_noise(noise.p1, noise.p2, noise.p_meas, noise.p_prep) + builder.with_num_measurements(int(tc.get_meta("num_measurements") or "0")) + builder.with_measurement_order(get_measurement_order_from_tick_circuit(tc)) + builder.with_detectors_json(detectors_json) + if observables_json: + builder.with_observables_json(observables_json) + return builder.build_with_source_tracking() + + legacy_dem = _build(tc.get_meta("detectors"), tc.get_meta("observables")) + public_dem = _build( + json.dumps(get_detector_descriptors_from_tick_circuit(tc, patch)), + json.dumps(get_observable_descriptors_from_tick_circuit(tc, patch)), + ) + + assert public_dem.to_string() == legacy_dem.to_string() + assert public_dem.num_contributions == legacy_dem.num_contributions + assert public_dem.all_contribution_effects() == legacy_dem.all_contribution_effects() + + +def _find_gate_attrs( + dag: object, + gate_type: str, + *, + phase: str | None = None, + label_prefix: str | None = None, + stabilizer: str | None = None, +) -> dict[str, object]: + """Find the first DAG gate attribute record matching the requested filters.""" + for node in sorted(dag.nodes()): + gate = dag.gate(node) + attrs = dag.gate_attrs(node) or {} + if gate is None or gate.gate_type.name != gate_type: + continue + if phase is not None and attrs.get("phase") != phase: + continue + if label_prefix is not None and not str(attrs.get("label", "")).startswith(label_prefix): + continue + if stabilizer is not None and attrs.get("stabilizer") != stabilizer: + continue + return attrs + msg = ( + f"no gate attrs found for gate_type={gate_type!r}, phase={phase!r}, " + f"label_prefix={label_prefix!r}, stabilizer={stabilizer!r}" + ) + raise AssertionError(msg) + + +def test_surface_tick_gate_metadata_preserves_phase_round_context_in_dag() -> None: + """Surface DAG metadata should retain round and stabilizer context.""" + from pecos.qec.surface import SurfacePatch, generate_tick_circuit_from_patch + + patch = SurfacePatch.create(distance=3) + tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="X") + dag = tc.to_dag_circuit() + + h_pre = _find_gate_attrs(dag, "H", phase="syndrome_h_pre") + assert h_pre["phase"] == "syndrome_h_pre" + assert h_pre["syndrome_round"] == 0 + assert "cx_round" not in h_pre + + ancilla_reset = _find_gate_attrs(dag, "PZ", phase="syndrome_prep", label_prefix="ax") + assert ancilla_reset["phase"] == "syndrome_prep" + assert ancilla_reset["syndrome_round"] == 1 + assert "cx_round" not in ancilla_reset + assert ancilla_reset["stabilizer"] == "X0" + assert ancilla_reset["stabilizer_kind"] == "X" + assert ancilla_reset["stabilizer_index"] == 0 + assert ancilla_reset["stabilizer_is_boundary"] is True + assert ancilla_reset["stabilizer_region"] + assert ancilla_reset["ancilla_qubit"] >= patch.num_data + + cx = _find_gate_attrs(dag, "CX", phase="cx_round_1") + assert cx["phase"] == "cx_round_1" + assert cx["syndrome_round"] == 0 + assert cx["cx_round"] == 1 + assert str(cx["stabilizer"]).startswith(("X", "Z")) + assert cx["stabilizer_kind"] in {"X", "Z"} + assert isinstance(cx["stabilizer_index"], int) + assert isinstance(cx["stabilizer_is_boundary"], bool) + assert cx["stabilizer_region"] + assert cx["touch_label"] in {"TL", "TR", "BL", "BR", "top", "bottom", "left", "right"} + assert cx["cx_round_0based"] == 0 + assert cx["ancilla_qubit"] >= patch.num_data + assert cx["data_qubit"] < patch.num_data + + ancilla_measure = _find_gate_attrs(dag, "MZ", phase="measure_ancilla", label_prefix="sx") + assert ancilla_measure["phase"] == "measure_ancilla" + assert ancilla_measure["syndrome_round"] == 0 + assert ancilla_measure["cx_round"] == 4 + assert ancilla_measure["stabilizer"] == "X0" + + +def test_surface_tick_gate_metadata_tracks_reused_ancillas_by_label() -> None: + """Ancilla labels should keep metadata stable even when qubits are reused.""" + from pecos.qec.surface import SurfacePatch, generate_tick_circuit_from_patch + + patch = SurfacePatch.create(distance=3) + tc = generate_tick_circuit_from_patch( + patch, + num_rounds=1, + basis="X", + ancilla_budget=2, + ) + dag = tc.to_dag_circuit() + + first_alloc = _find_gate_attrs(dag, "QAlloc", phase="syndrome_prep", label_prefix="ax0") + reused_reset = _find_gate_attrs(dag, "PZ", phase="syndrome_prep", label_prefix="ax1") + reused_cx = _find_gate_attrs(dag, "CX", phase="cx_round_1", stabilizer="X1") + + assert first_alloc["stabilizer"] == "X0" + assert reused_reset["stabilizer"] == "X1" + assert reused_reset["ancilla_qubit"] == first_alloc["ancilla_qubit"] + assert reused_reset["ancilla_qubit"] == patch.num_data + assert reused_cx["stabilizer"] == "X1" + assert reused_cx["ancilla_qubit"] == patch.num_data + + +@pytest.mark.parametrize("distance", [FAST_DISTANCE, SLOW_DISTANCE]) +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_native_decomposed_components_are_graphlike_and_map_back_to_full_dem(distance: int, basis: str) -> None: + """Native decomposed graphlike pieces should reconstruct a full DEM effect.""" + from pecos.qec.surface import SurfacePatch, generate_tick_circuit_from_patch + from pecos.qec.surface.circuit_builder import generate_dem_from_tick_circuit + + patch = SurfacePatch.create(distance=distance) + tc = generate_tick_circuit_from_patch(patch, num_rounds=20, basis=basis) + params = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} + + full_dem = generate_dem_from_tick_circuit(tc, **params, decompose_errors=False) + native_decomp_dem = generate_dem_from_tick_circuit(tc, **params, decompose_errors=True) + + fuldem_outputs, _ = parse_dem_with_decomposed(full_dem) + _direct_targets, decomposed_targets = parse_dem_with_decomposed(native_decomp_dem) + + assert decomposed_targets, "expected representative circuit to contain decomposed terms" + + saw_l0_decomposition = False + for parts in decomposed_targets: + for dets, logs in parts: + assert len(dets) <= 2, f"component is not graphlike by detector count: {parts!r}" + assert len(logs) <= 1, f"component is not graphlike by logical count: {parts!r}" + + combined = xor_targets(parts) + msg = f"decomposed components must XOR back to an effect present in the full DEM: {parts!r} -> {combined!r}" + assert combined in fuldem_outputs, msg + + if combined[1]: + saw_l0_decomposition = True + + assert saw_l0_decomposition, "expected representative circuit to include decomposed L0 terms" + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_native_decomposed_matches_stim_singleton_l0_edges_for_representative_circuit(basis: str) -> None: + """Native decomposition should preserve Stim's singleton logical-observable edges.""" + from pecos.qec.surface import SurfacePatch, generate_tick_circuit_from_patch + from pecos.qec.surface.circuit_builder import ( + generate_dem_from_tick_circuit, + generate_dem_from_tick_circuit_via_stim, + ) + + patch = SurfacePatch.create(distance=3) + tc = generate_tick_circuit_from_patch(patch, num_rounds=20, basis=basis) + params = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} + + native_decomp_dem = generate_dem_from_tick_circuit(tc, **params, decompose_errors=True) + stim_dem = generate_dem_from_tick_circuit_via_stim(tc, **params) + + native_direct, _ = parse_dem_with_decomposed(native_decomp_dem) + stim_direct, _ = parse_dem_with_decomposed(stim_dem) + + assert singleton_l0_edges(native_direct) == singleton_l0_edges(stim_direct) + + +@pytest.mark.parametrize("distance", [FAST_DISTANCE, SLOW_DISTANCE]) +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_native_decomposed_preserves_all_stim_direct_observable_targets(distance: int, basis: str) -> None: + """Native decomposition should include every direct observable target Stim exposes.""" + from pecos.qec.surface import SurfacePatch, generate_tick_circuit_from_patch + from pecos.qec.surface.circuit_builder import ( + generate_dem_from_tick_circuit, + generate_dem_from_tick_circuit_via_stim, + ) + + patch = SurfacePatch.create(distance=distance) + tc = generate_tick_circuit_from_patch(patch, num_rounds=20, basis=basis) + params = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} + + native_decomp_dem = generate_dem_from_tick_circuit(tc, **params, decompose_errors=True) + stim_dem = generate_dem_from_tick_circuit_via_stim(tc, **params) + + native_direct, _ = parse_dem_with_decomposed(native_decomp_dem) + stim_direct, _ = parse_dem_with_decomposed(stim_dem) + + native_observable_direct = {target for target in native_direct if target[1]} + stim_observable_direct = {target for target in stim_direct if target[1]} + + assert stim_observable_direct.issubset(native_observable_direct) + assert all(len(dets) == 2 and len(logs) == 1 for dets, logs in native_observable_direct - stim_observable_direct) + + +@pytest.mark.parametrize("distance", [FAST_DISTANCE, SLOW_DISTANCE]) +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_native_full_matches_stim_full_graph_summary_for_representative_circuit(distance: int, basis: str) -> None: + """Full native and Stim DEMs should produce matching PyMatching graph summaries.""" + from pecos.qec.surface import SurfacePatch, generate_tick_circuit_from_patch + from pecos.qec.surface.circuit_builder import ( + generate_dem_from_tick_circuit, + generate_dem_from_tick_circuit_via_stim, + ) + from pecos_rslib.decoders import PyMatchingDecoder + + patch = SurfacePatch.create(distance=distance) + tc = generate_tick_circuit_from_patch(patch, num_rounds=20, basis=basis) + params = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} + + native_full_dem = generate_dem_from_tick_circuit(tc, **params, decompose_errors=False) + stim_full_dem = generate_dem_from_tick_circuit_via_stim(tc, **params, decompose_errors=False) + + native_graph = PyMatchingDecoder.from_dem(native_full_dem) + stim_graph = PyMatchingDecoder.from_dem(stim_full_dem) + + assert native_graph.num_detectors == stim_graph.num_detectors + assert native_graph.num_edges == stim_graph.num_edges + assert native_graph.num_observables == stim_graph.num_observables + + +def test_generate_dem_from_tick_circuit_via_stim_can_skip_decomposition() -> None: + """Stim DEM generation should honor the explicit non-decomposed option.""" + from pecos.qec.surface import SurfacePatch, generate_tick_circuit_from_patch + from pecos.qec.surface.circuit_builder import generate_dem_from_tick_circuit_via_stim + + patch = SurfacePatch.create(distance=3) + tc = generate_tick_circuit_from_patch(patch, num_rounds=4, basis="X") + + dem = generate_dem_from_tick_circuit_via_stim( + tc, + p1=0.01, + p2=0.01, + p_meas=0.01, + p_prep=0.01, + decompose_errors=False, + ) + + assert "error(" in dem + assert "^" not in dem + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_structured_source_tracking_summaries_include_graphlike_decomposable_count(basis: str) -> None: + """Structured summaries should expose graphlike decomposition counts.""" + dem = build_source_tracked_dem(distance=3, basis=basis, rounds=20) + + summaries = dem.contribution_effect_summaries() + assert summaries + + pair_summaries = [summary for summary in summaries if len(summary["detectors"]) == 2 and not summary["dem_outputs"]] + assert pair_summaries + assert all("graphlike_decomposable_count" in summary for summary in pair_summaries) + assert all(summary["graphlike_decomposable_count"] >= 0 for summary in pair_summaries) + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_structured_source_tracking_bindings_are_self_consistent(basis: str) -> None: + """Structured contribution rows should sum back to their effect summaries.""" + dem = build_source_tracked_dem(distance=3, basis=basis, rounds=20) + + summaries = dem.contribution_effect_summaries() + assert summaries + + observable_summary = next(row for row in summaries if row["dem_outputs"]) + contributions = dem.contributions_for_effect( + observable_summary["detectors"], + observable_summary["dem_outputs"], + ) + + assert contributions + assert len(contributions) == observable_summary["num_contributions"] + + total_probability = sum(float(row["probability"]) for row in contributions) + direct_rows = [row for row in contributions if row["source_type"] in DIRECT_SOURCE_TYPES] + y_rows = [row for row in contributions if row["source_type"] == "YDecomposed"] + assert all(row["location_indices"] for row in contributions) + assert all(row["pauli_labels"] for row in contributions) + assert all("gate_type_labels" in row for row in contributions) + assert all("before_flags" in row for row in contributions) + assert all(len(row["location_indices"]) == len(row["pauli_labels"]) for row in contributions) + assert all(len(row["location_indices"]) == len(row["gate_type_labels"]) for row in contributions) + assert all(len(row["location_indices"]) == len(row["before_flags"]) for row in contributions) + assert all(all(label in {"I", "X", "Y", "Z"} for label in row["pauli_labels"]) for row in contributions) + assert all(all(label for label in row["gate_type_labels"]) for row in contributions) + assert total_probability == pytest.approx(observable_summary["total_probability"]) + assert len(direct_rows) == observable_summary["direct_count"] + assert sum(float(row["probability"]) for row in direct_rows) == pytest.approx( + observable_summary["direct_probability"], + ) + assert len(y_rows) == observable_summary["y_decomposed_count"] + assert sum(float(row["probability"]) for row in y_rows) == pytest.approx( + observable_summary["y_decomposed_probability"], + ) + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_structured_source_tracking_y_decomposed_rows_xor_back_to_effect(basis: str) -> None: + """Y-decomposed structured rows should XOR back to their parent effect.""" + dem = build_source_tracked_dem(distance=3, basis=basis, rounds=20) + + summaries = [row for row in dem.contribution_effect_summaries() if row["y_decomposed_count"] > 0] + assert summaries + + for summary in summaries[:20]: + contributions = dem.contributions_for_effect(summary["detectors"], summary["dem_outputs"]) + y_rows = [row for row in contributions if row["source_type"] == "YDecomposed"] + assert y_rows + for row in y_rows: + assert xor_lists(row["x_detectors"], row["z_detectors"]) == summary["detectors"] + assert xor_lists(row["x_dem_outputs"], row["z_dem_outputs"]) == summary["dem_outputs"] + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_structured_direct_component_rows_xor_back_to_effect(basis: str) -> None: + """Stored direct components should reconstruct the parent effect via XOR.""" + dem = build_source_tracked_dem(distance=3, basis=basis, rounds=20) + + rows = [] + for summary in dem.contribution_effect_summaries(): + for row in dem.contributions_for_effect(summary["detectors"], summary["dem_outputs"]): + if row["source_type"] not in DIRECT_SOURCE_TYPES: + continue + if "component_1_detectors" not in row or "component_2_detectors" not in row: + continue + rows.append((summary, row)) + + assert rows + + for summary, row in rows[:100]: + left = { + "detectors": row["component_1_detectors"], + "dem_outputs": row["component_1_dem_outputs"], + } + right = { + "detectors": row["component_2_detectors"], + "dem_outputs": row["component_2_dem_outputs"], + } + dets, logs = xor_effect_rows(left, right) + assert dets == summary["detectors"] + assert logs == summary["dem_outputs"] + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_structured_one_sided_direct_component_rows_are_exposed(basis: str) -> None: + """One-sided direct components should remain visible in the structured bindings.""" + dem = build_source_tracked_dem(distance=3, basis=basis, rounds=20) + + rows = [] + for summary in dem.contribution_effect_summaries(): + for row in dem.contributions_for_effect(summary["detectors"], summary["dem_outputs"]): + if row["source_type"] != "DirectOneSidedComponent": + continue + rows.append((summary, row)) + + assert rows + + for summary, row in rows[:100]: + left_non_empty = bool(row["component_1_detectors"] or row["component_1_dem_outputs"]) + right_non_empty = bool(row["component_2_detectors"] or row["component_2_dem_outputs"]) + assert left_non_empty != right_non_empty + assert row["direct_source_family"] == "TwoLocationOneSidedComponent" + direct_dets, direct_logs = xor_effect_rows( + { + "detectors": row["component_1_detectors"], + "dem_outputs": row["component_1_dem_outputs"], + }, + { + "detectors": row["component_2_detectors"], + "dem_outputs": row["component_2_dem_outputs"], + }, + ) + assert direct_dets == summary["detectors"] + assert direct_logs == summary["dem_outputs"] + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_structured_direct_source_families_are_exposed_for_direct_rows(basis: str) -> None: + """Direct structured rows should advertise their underlying source family.""" + dem = build_source_tracked_dem(distance=3, basis=basis, rounds=20) + + rows = [] + for summary in dem.contribution_effect_summaries(): + rows.extend( + row + for row in dem.contributions_for_effect(summary["detectors"], summary["dem_outputs"]) + if row["source_type"] in DIRECT_SOURCE_TYPES + ) + + assert rows + assert all("direct_source_family" in row for row in rows) + assert any(row["direct_source_family"] == "SingleLocationY" for row in rows) + assert any(row["direct_source_family"] == "TwoLocationOneSidedComponent" for row in rows) + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_structured_source_tracking_summaries_partition_all_contributions(basis: str) -> None: + """Effect summaries should form a lossless partition of all contributions.""" + dem = build_source_tracked_dem(distance=3, basis=basis, rounds=20) + + summaries = dem.contribution_effect_summaries() + assert summaries + + effect_keys = {(tuple(summary["detectors"]), tuple(summary["dem_outputs"])) for summary in summaries} + assert len(effect_keys) == len(summaries) + + total_count = 0 + total_probability = 0.0 + for summary in summaries: + contributions = dem.contributions_for_effect(summary["detectors"], summary["dem_outputs"]) + total_count += len(contributions) + total_probability += sum(float(row["probability"]) for row in contributions) + assert all(row["detectors"] == summary["detectors"] for row in contributions) + assert all(row["dem_outputs"] == summary["dem_outputs"] for row in contributions) + + assert total_count == dem.num_contributions + assert total_count == sum(int(summary["num_contributions"]) for summary in summaries) + assert total_probability == pytest.approx(sum(float(summary["total_probability"]) for summary in summaries)) + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_structured_render_summaries_reproduce_decomposed_regrouping(basis: str) -> None: + """Render summaries should regroup into the same decomposed DEM probabilities.""" + dem = build_source_tracked_dem(distance=3, basis=basis, rounds=20) + + render_summaries = dem.contribution_render_summaries() + assert render_summaries + assert sum(int(row["num_contributions"]) for row in render_summaries) == dem.num_contributions + + decomposed_by_targets = parse_dem_error_probabilities(dem.to_string_decomposed()) + regrouped_from_summaries: dict[str, float] = {} + for row in render_summaries: + regrouped_from_summaries[row["rendered_targets"]] = combine_independent_probs( + regrouped_from_summaries.get(row["rendered_targets"], 0.0), + float(row["combined_probability"]), + ) + + assert set(regrouped_from_summaries) == set(decomposed_by_targets) + for targets, probability in regrouped_from_summaries.items(): + assert probability == pytest.approx(decomposed_by_targets[targets], abs=5e-7) + + assert all("source_type_counts" in row for row in render_summaries) + assert any("YDecomposed" in row["source_type_counts"] for row in render_summaries) + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_structured_render_records_reproduce_render_summaries(basis: str) -> None: + """Per-contribution render records should rebuild the grouped render summaries.""" + dem = build_source_tracked_dem(distance=3, basis=basis, rounds=20) + + render_records = dem.contribution_render_records() + render_summaries = dem.contribution_render_summaries() + + assert render_records + assert len(render_records) == dem.num_contributions + assert all("rendered_targets" in row for row in render_records) + assert all("render_strategy" in row for row in render_records) + assert any("recorded_component_targets" in row for row in render_records) + + regrouped: dict[tuple[tuple[int, ...], tuple[int, ...], str], dict[str, object]] = {} + for row in render_records: + key = ( + tuple(row["detectors"]), + tuple(row["dem_outputs"]), + str(row["rendered_targets"]), + ) + bucket = regrouped.setdefault( + key, + { + "num_contributions": 0, + "total_probability": 0.0, + "combined_probability": 0.0, + "source_type_counts": {}, + "source_type_probabilities": {}, + "direct_source_family_counts": {}, + "direct_source_family_probabilities": {}, + }, + ) + bucket["num_contributions"] += 1 + bucket["total_probability"] += float(row["probability"]) + bucket["combined_probability"] = combine_xor_probs( + float(bucket["combined_probability"]), + float(row["probability"]), + ) + + source_type = str(row["source_type"]) + bucket["source_type_counts"][source_type] = bucket["source_type_counts"].get(source_type, 0) + 1 + bucket["source_type_probabilities"][source_type] = bucket["source_type_probabilities"].get( + source_type, + 0.0, + ) + float( + row["probability"], + ) + + direct_family = row.get("direct_source_family") + if direct_family is not None: + direct_family = str(direct_family) + bucket["direct_source_family_counts"][direct_family] = ( + bucket["direct_source_family_counts"].get(direct_family, 0) + 1 + ) + bucket["direct_source_family_probabilities"][direct_family] = bucket[ + "direct_source_family_probabilities" + ].get(direct_family, 0.0) + float(row["probability"]) + + assert len(regrouped) == len(render_summaries) + for summary in render_summaries: + key = ( + tuple(summary["detectors"]), + tuple(summary["dem_outputs"]), + str(summary["rendered_targets"]), + ) + bucket = regrouped[key] + assert int(bucket["num_contributions"]) == int(summary["num_contributions"]) + assert float(bucket["total_probability"]) == pytest.approx(float(summary["total_probability"])) + assert float(bucket["combined_probability"]) == pytest.approx(float(summary["combined_probability"])) + assert bucket["source_type_counts"] == summary["source_type_counts"] + assert bucket["direct_source_family_counts"] == summary["direct_source_family_counts"] + assert bucket["source_type_probabilities"] == pytest.approx(summary["source_type_probabilities"]) + assert bucket["direct_source_family_probabilities"] == pytest.approx( + summary["direct_source_family_probabilities"], + ) + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_structured_keep_direct_policy_matches_default_render_outputs(basis: str) -> None: + """The explicit KeepDirect policy should match the default rendering behavior.""" + dem = build_source_tracked_dem(distance=3, basis=basis, rounds=20) + + assert dem.to_string_decomposed_with_two_detector_direct_policy("KeepDirect") == dem.to_string_decomposed() + assert ( + dem.contribution_render_summaries_with_two_detector_direct_policy("KeepDirect") + == dem.contribution_render_summaries() + ) + assert ( + dem.contribution_render_records_with_two_detector_direct_policy("KeepDirect") + == dem.contribution_render_records() + ) + + +@pytest.mark.parametrize("basis", ["X", "Z"]) +def test_structured_recorded_component_policy_exposes_alternative_records(basis: str) -> None: + """Recorded-component policy should expose alternate render strategies and targets.""" + dem = build_source_tracked_dem(distance=3, basis=basis, rounds=20) + + default_records = dem.contribution_render_records() + policy_records = dem.contribution_render_records_with_two_detector_direct_policy( + "PreferRecordedComponents", + ) + + assert len(policy_records) == len(default_records) + assert any(row["render_strategy"] == "RecordedComponents" for row in policy_records) + assert any( + policy_row["rendered_targets"] != default_row["rendered_targets"] + for default_row, policy_row in zip(default_records, policy_records, strict=False) + ) diff --git a/python/quantum-pecos/tests/qec/test_dem_equivalence.py b/python/quantum-pecos/tests/qec/test_dem_equivalence.py index 1ccb9566f..cf653246b 100644 --- a/python/quantum-pecos/tests/qec/test_dem_equivalence.py +++ b/python/quantum-pecos/tests/qec/test_dem_equivalence.py @@ -14,7 +14,7 @@ ) -class TestErrorMechanismParsing: +class TestFaultMechanismParsing: """Test parsing of error mechanisms.""" def test_parse_simple_mechanism(self) -> None: @@ -25,15 +25,18 @@ def test_parse_simple_mechanism(self) -> None: assert dem.num_mechanisms == 1 assert dem.num_detectors == 2 assert dem.num_observables == 0 + assert dem.num_tracked_ops == 0 - def test_parse_mechanism_with_observable(self) -> None: - """Parse mechanism with observable.""" + def test_parse_mechanism_with_tracked_op(self) -> None: + """Parse mechanism with a Stim DEM output exposed as a tracked op.""" dem_str = "error(0.02) D0 L0" dem = ParsedDem.from_string(dem_str) assert dem.num_mechanisms == 1 assert dem.num_detectors == 1 + assert dem.num_dem_outputs == 1 assert dem.num_observables == 1 + assert dem.num_tracked_ops == 0 def test_parse_decomposed_mechanism(self) -> None: """Parse a decomposed mechanism (XOR chain).""" @@ -55,7 +58,9 @@ def test_parse_multiple_mechanisms(self) -> None: assert dem.num_mechanisms == 3 assert dem.num_detectors == 3 + assert dem.num_dem_outputs == 1 assert dem.num_observables == 1 + assert dem.num_tracked_ops == 0 def test_parse_detector_declarations(self) -> None: """Parse detector declarations.""" @@ -337,7 +342,7 @@ def surface_code_dem(self) -> tuple[str, str]: patch = SurfacePatch.create(distance=3) tc = generate_tick_circuit_from_patch(patch, num_rounds=1, basis="Z") - noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_init": 0.01} + noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} pecos_dem = generate_dem_from_tick_circuit(tc, **noise, decompose_errors=False) @@ -403,7 +408,7 @@ def surface_code_dem_pair(self) -> tuple[str, str]: patch = SurfacePatch.create(distance=3) tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="Z") - noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_init": 0.01} + noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} raw_dem = generate_dem_from_tick_circuit(tc, **noise, decompose_errors=False) decomposed_dem = generate_dem_from_tick_circuit( @@ -523,7 +528,7 @@ def test_decomposition_equivalence_various_sizes( patch = SurfacePatch.create(distance=distance) tc = generate_tick_circuit_from_patch(patch, num_rounds=num_rounds, basis="Z") - noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_init": 0.01} + noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} raw_dem_str = generate_dem_from_tick_circuit( tc, diff --git a/python/quantum-pecos/tests/qec/test_dem_probability_analysis.py b/python/quantum-pecos/tests/qec/test_dem_probability_analysis.py index b78296090..6be66cc3e 100644 --- a/python/quantum-pecos/tests/qec/test_dem_probability_analysis.py +++ b/python/quantum-pecos/tests/qec/test_dem_probability_analysis.py @@ -236,7 +236,7 @@ def test_dem_comparison_d3() -> None: p1 = 0.01 p2 = 0.01 p_meas = 0.01 - p_init = 0.01 + p_prep = 0.01 # Generate DEMs pecos_dem = generate_dem_from_tick_circuit( @@ -244,7 +244,7 @@ def test_dem_comparison_d3() -> None: p1=p1, p2=p2, p_meas=p_meas, - p_init=p_init, + p_prep=p_prep, decompose_errors=False, ) stim_dem = generate_dem_from_tick_circuit_via_stim( @@ -252,7 +252,7 @@ def test_dem_comparison_d3() -> None: p1=p1, p2=p2, p_meas=p_meas, - p_init=p_init, + p_prep=p_prep, ) print("\n--- PECOS DEM (raw, no decomposition) ---") @@ -417,14 +417,14 @@ def analyze_decomposition_pattern() -> None: patch = SurfacePatch.create(distance=3) tc = generate_tick_circuit_from_patch(patch, num_rounds=1, basis="Z") - p1, p2, p_meas, p_init = 0.01, 0.01, 0.01, 0.01 + p1, p2, p_meas, p_prep = 0.01, 0.01, 0.01, 0.01 stim_dem = generate_dem_from_tick_circuit_via_stim( tc, p1=p1, p2=p2, p_meas=p_meas, - p_init=p_init, + p_prep=p_prep, ) errors, decomposed = parse_stim_dem_with_decomposed(stim_dem) @@ -459,7 +459,7 @@ def analyze_decomposition_pattern() -> None: p1=p1, p2=p2, p_meas=p_meas, - p_init=p_init, + p_prep=p_prep, decompose_errors=False, ) pecos_errors = parse_dem(pecos_dem) diff --git a/python/quantum-pecos/tests/qec/test_dem_sampler.py b/python/quantum-pecos/tests/qec/test_dem_sampler.py index 65825a815..bea1fc5b4 100644 --- a/python/quantum-pecos/tests/qec/test_dem_sampler.py +++ b/python/quantum-pecos/tests/qec/test_dem_sampler.py @@ -60,6 +60,10 @@ def test_dem_sampler_sampling() -> None: builder.with_observables_json('[{"id": 0, "records": [-1]}]') sampler = builder.build() + assert sampler.num_dem_outputs == 1 + assert sampler.num_observables == 1 + assert sampler.num_tracked_ops == 0 + # Single sample det_events, obs_flips = sampler.sample(seed=42) assert isinstance(det_events, list) @@ -129,12 +133,186 @@ def test_dem_sampler_statistics() -> None: assert "logical_error_rate" in stats assert "syndrome_rate" in stats assert "undetectable_rate" in stats + assert "per_dem_output" in stats + assert "dem_output_rates" in stats + assert stats["per_dem_output"] == stats["per_observable"] + assert stats["dem_output_rates"] == stats["logical_rates"] assert stats["total_shots"] == 10000 assert 0.0 <= stats["logical_error_rate"] <= 1.0 assert 0.0 <= stats["syndrome_rate"] <= 1.0 +def test_dem_sampler_tracked_op_labels() -> None: + """Test sampler labels expose PECOS tracked-op terminology.""" + from pecos_rslib import DagCircuit, PauliString + from pecos_rslib.qec import DemSampler + + dag = DagCircuit() + dag.pz([0]) + dag.h([0]) + dag.pauli_operator(PauliString.from_str("X"), label="x_check") + + sampler = DemSampler.from_circuit(dag, p1=0.03, p2=0.0, p_meas=0.0, p_prep=0.0) + + labels = sampler.labels() + + assert sampler.num_tracked_ops == 1 + assert sampler.num_dem_outputs == 0 + assert sampler.num_observables == 0 + assert "dem_outputs" in labels + assert "tracked_ops" in labels + assert labels["dem_outputs"] == [] + assert labels["tracked_ops"] == ["x_check"] + + stats = sampler.sample_statistics(2000, seed=7) + assert stats["logical_error_count"] == 0 + assert stats["per_observable"] == [] + assert stats["per_tracked_op"] == [] + assert stats["per_dem_output"] == [] + + +def test_dem_events_split_observables_and_tracked_ops() -> None: + """DEM summaries report detector, observable, and tracked-operator effects separately.""" + from pecos_rslib import DagCircuit, PauliString + from pecos_rslib.qec import DetectorErrorModel + + dag = DagCircuit() + dag.pz([0]) + dag.h([0]) + dag.pauli_operator(PauliString.from_str("X"), label="x_check") + dag.mz([0]) + dag.set_attr("num_measurements", "1") + dag.set_attr("observables", '[{"id": 0, "records": [-1]}]') + + dem = DetectorErrorModel.from_circuit( + dag, p1=0.03, p2=0.0, p_meas=0.02, p_prep=0.0 + ) + sampler = dem.to_sampler() + + assert dem.num_dem_outputs == 1 + assert dem.num_observables == 1 + assert dem.num_tracked_ops == 1 + assert sampler.num_dem_outputs == 1 + assert sampler.num_observables == 1 + assert sampler.num_tracked_ops == 1 + assert sampler.labels()["tracked_ops"] == ["x_check"] + + summaries = dem.contribution_effect_summaries() + assert summaries + assert all("dem_outputs" in row for row in summaries) + assert all("observables" in row for row in summaries) + assert all("tracked_ops" in row for row in summaries) + + observable_hits = {idx for row in summaries for idx in row["observables"]} + tracked_hits = {idx for row in summaries for idx in row["tracked_ops"]} + assert 0 in observable_hits + assert tracked_hits == set() + + +def test_sample_decode_count_ignores_tracked_ops() -> None: + """Decoder error counting uses observables, not tracked operators.""" + from pecos_rslib import DagCircuit, PauliString + from pecos_rslib.qec import DemSampler, DetectorErrorModel + + dag = DagCircuit() + dag.pz([0]) + dag.pz([1]) + dag.h([1]) + dag.pauli_operator(PauliString.from_str("IZ"), label="tracked_z") + dag.mz([0]) + dag.set_attr("num_measurements", "1") + dag.set_attr("detectors", '[{"id": 0, "records": [-1]}]') + dag.set_attr("observables", '[{"id": 0, "records": [-1]}]') + + sampler = DemSampler.from_circuit( + dag, p1=0.4, p2=0.0, p_meas=0.15, p_prep=0.0 + ) + dem = DetectorErrorModel.from_circuit( + dag, p1=0.4, p2=0.0, p_meas=0.15, p_prep=0.0 + ) + + assert sampler.num_dem_outputs == 1 + assert sampler.num_observables == 1 + assert sampler.num_tracked_ops == 1 + assert "logical_observable L0" in dem.to_string() + assert "logical_observable L1" not in dem.to_string() + + errors = sampler.sample_decode_count(dem.to_string(), 2000, seed=17) + assert errors == 0 + + +def test_influence_map_tracks_dem_outputs_and_tracked_ops_separately() -> None: + """Test influence maps expose DEM outputs and filtered tracked operators.""" + from pecos_rslib import DagCircuit + from pecos_rslib.qec import InfluenceBuilder + + dag = DagCircuit() + dag.pz([0]) + dag.h([0]) + + builder = InfluenceBuilder(dag) + builder.with_pauli_operator([(0, "X")]) + influence_map = builder.build() + + assert influence_map.num_tracked_ops > 0 + assert influence_map.num_observables == 0 + assert influence_map.num_dem_outputs == 0 + + csr = influence_map.export_csr() + assert csr["num_dem_outputs"] == influence_map.num_dem_outputs + assert csr["num_internal_dem_outputs"] == influence_map.num_tracked_ops + assert csr["num_observables"] == 0 + assert csr["num_tracked_ops"] == influence_map.num_tracked_ops + assert "dem_output_offsets_x" in csr + assert "dem_output_data_x" in csr + + for loc_idx in range(influence_map.num_locations): + tracked = influence_map.get_tracked_op_indices(loc_idx, 1) + dem_outputs = influence_map.get_dem_output_indices(loc_idx, 1) + internal_dem_outputs = influence_map.get_internal_dem_output_indices(loc_idx, 1) + assert dem_outputs == [] + assert tracked == internal_dem_outputs + assert not influence_map.has_dem_output_flips(loc_idx, 1) + assert influence_map.has_tracked_op_flips(loc_idx, 1) == bool(tracked) + + +def test_influence_builder_does_not_add_empty_tracked_ops() -> None: + """An unconfigured Python InfluenceBuilder should not create identity tracked ops.""" + from pecos_rslib import DagCircuit + from pecos_rslib.qec import InfluenceBuilder + + dag = DagCircuit() + dag.pz([0]) + dag.h([0]) + dag.mz([0]) + + influence_map = InfluenceBuilder(dag).build() + + assert influence_map.num_dem_outputs == 0 + assert influence_map.num_observables == 0 + assert influence_map.num_tracked_ops == 0 + + +def test_influence_builder_tracked_x_z_are_dem_outputs() -> None: + """Tracked X/Z helpers create tracked operators, not observables.""" + from pecos_rslib import DagCircuit + from pecos_rslib.qec import InfluenceBuilder + + dag = DagCircuit() + dag.pz([0]) + dag.h([0]) + + builder = InfluenceBuilder(dag) + builder.with_tracked_x([0]) + builder.with_tracked_z([0]) + influence_map = builder.build() + + assert influence_map.num_dem_outputs == 0 + assert influence_map.num_observables == 0 + assert influence_map.num_tracked_ops == 2 + + def test_dem_sampler_zero_noise() -> None: """Test that zero noise produces no errors.""" from pecos_rslib import DagCircuit @@ -181,7 +359,8 @@ def test_dem_sampler_repr() -> None: repr_str = repr(sampler) assert "DemSampler" in repr_str assert "mechanisms" in repr_str - assert "detectors" in repr_str + assert "dem_outputs" in repr_str + assert "tracked_ops" in repr_str if __name__ == "__main__": diff --git a/python/quantum-pecos/tests/qec/test_dem_sampler_modes.py b/python/quantum-pecos/tests/qec/test_dem_sampler_modes.py new file mode 100644 index 000000000..c0d8eedf1 --- /dev/null +++ b/python/quantum-pecos/tests/qec/test_dem_sampler_modes.py @@ -0,0 +1,246 @@ +# Copyright 2026 The PECOS Developers +# +# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +# in compliance with the License. You may obtain a copy of the License at +# +# https://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software distributed under the License +# is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +# or implied. See the License for the specific language governing permissions and limitations under +# the License. + +"""Tests for DemSampler Python bindings.""" + +from __future__ import annotations + +from typing import TYPE_CHECKING + +import pytest +from pecos.qec import DagFaultAnalyzer, DemSampler, DemSamplerBuilder +from pecos_rslib import DagCircuit + +if TYPE_CHECKING: + from pecos.qec import DagFaultInfluenceMap + + +def _build_repetition_code_circuit(num_rounds: int = 3) -> DagCircuit: + """Build a simple repetition code circuit.""" + dag = DagCircuit() + for _ in range(num_rounds): + dag.pz([3]) + dag.pz([4]) + dag.cx([(0, 3)]) + dag.cx([(1, 3)]) + dag.cx([(1, 4)]) + dag.cx([(2, 4)]) + dag.mz([3]) + dag.mz([4]) + return dag + + +def _build_influence_map(dag: DagCircuit) -> DagFaultInfluenceMap: + """Build influence map with logical Z.""" + analyzer = DagFaultAnalyzer(dag) + return analyzer.build_influence_map() + + +class TestDemSamplerRawMode: + """Test raw measurement output mode.""" + + def test_raw_uniform_creates_sampler(self) -> None: + """Test that raw_uniform constructor creates a valid sampler.""" + dag = _build_repetition_code_circuit(2) + im = _build_influence_map(dag) + sampler = DemSampler.raw_uniform(im, 0.01) + assert sampler.num_mechanisms > 0 + + def test_raw_circuit_noise_creates_sampler(self) -> None: + """Test that raw constructor with per-gate noise creates a valid sampler.""" + dag = _build_repetition_code_circuit(2) + im = _build_influence_map(dag) + sampler = DemSampler.raw(im, 0.001, 0.01, 0.005, 0.001) + assert sampler.num_mechanisms > 0 + + def test_raw_sample_returns_correct_shape(self) -> None: + """Test that raw sample returns non-empty output and observable lists.""" + dag = _build_repetition_code_circuit(2) + im = _build_influence_map(dag) + sampler = DemSampler.raw_uniform(im, 0.01) + outputs, obs = sampler.sample(seed=42) + assert isinstance(outputs, list) + assert isinstance(obs, list) + assert len(outputs) > 0 + + def test_raw_sample_batch(self) -> None: + """Test that sample_batch returns the requested number of shots.""" + dag = _build_repetition_code_circuit(2) + im = _build_influence_map(dag) + sampler = DemSampler.raw_uniform(im, 0.01) + all_outputs, _all_obs = sampler.sample_batch(100, seed=42) + assert len(all_outputs) == 100 + + def test_raw_zero_noise_statistics(self) -> None: + """Test that zero noise produces no syndromes or logical errors.""" + dag = _build_repetition_code_circuit(2) + im = _build_influence_map(dag) + sampler = DemSampler.raw_uniform(im, 0.0) + stats = sampler.sample_statistics(1000, seed=42) + assert stats["syndrome_count"] == 0 + assert stats["logical_error_count"] == 0 + + def test_raw_high_noise_produces_syndromes(self) -> None: + """Test that high noise produces a non-trivial syndrome rate.""" + dag = _build_repetition_code_circuit(2) + im = _build_influence_map(dag) + sampler = DemSampler.raw_uniform(im, 0.1) + stats = sampler.sample_statistics(5000, seed=42) + assert stats["syndrome_rate"] > 0.05 + + +class TestDemSamplerDetectorMode: + """Test detector-event output mode.""" + + def test_detector_mode_creates_sampler(self) -> None: + """Test that detector mode creates a sampler with correct output counts.""" + dag = _build_repetition_code_circuit(2) + im = _build_influence_map(dag) + sampler = DemSampler.with_detectors( + im, + detectors=[[-1], [-2]], + observables=[], + p1=0.001, + p2=0.01, + p_meas=0.005, + p_prep=0.001, + ) + assert sampler.num_outputs == 2 + assert sampler.num_observables == 0 + + def test_detector_mode_sample_shape(self) -> None: + """Test detector mode sample returns detector and observable counts.""" + dag = _build_repetition_code_circuit(2) + im = _build_influence_map(dag) + sampler = DemSampler.with_detectors( + im, + detectors=[[-1], [-2]], + observables=[[-1]], + p1=0.001, + p2=0.01, + p_meas=0.005, + p_prep=0.001, + ) + det_events, obs_flips = sampler.sample(seed=42) + assert len(det_events) == 2 + assert len(obs_flips) == 1 + assert sampler.num_dem_outputs == 1 + assert sampler.num_observables == 1 + assert sampler.num_tracked_ops == 0 + + def test_detector_mode_matches_dem_sampler_builder(self) -> None: + """DemSampler detector mode should match DemSamplerBuilder exactly.""" + dag = _build_repetition_code_circuit(3) + im = _build_influence_map(dag) + + p1, p2, p_meas, p_prep = 0.001, 0.01, 0.005, 0.001 + det_records = [[-1], [-2]] + obs_records = [] + num_shots = 20_000 + seed = 42 + + # DemSamplerBuilder path + import json + + det_json = json.dumps([{"id": i, "records": r} for i, r in enumerate(det_records)]) + obs_json = json.dumps([{"id": i, "records": r} for i, r in enumerate(obs_records)]) + dem_sampler = ( + DemSamplerBuilder(im) + .with_noise(p1, p2, p_meas, p_prep) + .with_detectors_json(det_json) + .with_observables_json(obs_json) + .build() + ) + dem_stats = dem_sampler.sample_statistics(num_shots, seed) + + # DemSampler detector mode + unified_sampler = DemSampler.with_detectors( + im, + detectors=det_records, + observables=obs_records, + p1=p1, + p2=p2, + p_meas=p_meas, + p_prep=p_prep, + ) + unified_stats = unified_sampler.sample_statistics(num_shots, seed) + + # Should match exactly (same seed → same internal DemSamplerBuilder path) + assert dem_stats["syndrome_count"] == unified_stats["syndrome_count"] + assert dem_stats["logical_error_count"] == unified_stats["logical_error_count"] + + +class TestDemSamplerValidation: + """Test detector definition validation.""" + + def test_linearly_dependent_detectors_rejected(self) -> None: + """Test that linearly dependent detector definitions are rejected.""" + dag = _build_repetition_code_circuit(2) + im = _build_influence_map(dag) + + # D2 = D0 XOR D1 → linearly dependent + with pytest.raises(ValueError, match="linearly independent"): + DemSampler.with_detectors( + im, + detectors=[[0], [1], [0, 1]], + observables=[], + p1=0.001, + p2=0.01, + p_meas=0.005, + p_prep=0.001, + ) + + def test_independent_detectors_accepted(self) -> None: + """Test that linearly independent detector definitions are accepted.""" + dag = _build_repetition_code_circuit(2) + im = _build_influence_map(dag) + + sampler = DemSampler.with_detectors( + im, + detectors=[[0], [1]], + observables=[], + p1=0.001, + p2=0.01, + p_meas=0.005, + p_prep=0.001, + ) + assert sampler.num_outputs == 2 + + +class TestDemSamplerRepr: + """Test string representation.""" + + def test_repr_raw_mode(self) -> None: + """Test repr output for raw mode sampler.""" + dag = _build_repetition_code_circuit(2) + im = _build_influence_map(dag) + sampler = DemSampler.raw_uniform(im, 0.01) + r = repr(sampler) + assert "DemSampler" in r + assert "DemSampler" in r + + def test_repr_detector_mode(self) -> None: + """Test repr output for detector mode sampler.""" + dag = _build_repetition_code_circuit(2) + im = _build_influence_map(dag) + sampler = DemSampler.with_detectors( + im, + detectors=[[-1]], + observables=[], + p1=0.01, + p2=0.01, + p_meas=0.01, + p_prep=0.01, + ) + r = repr(sampler) + assert "DemSampler" in r + assert "DemSampler" in r diff --git a/python/quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py b/python/quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py index c99668f13..f446b1dd9 100644 --- a/python/quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py +++ b/python/quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py @@ -154,7 +154,7 @@ def surface_code_d3(self) -> tuple: @pytest.fixture def noise_params(self) -> dict[str, float]: """Standard noise parameters for testing.""" - return {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_init": 0.01} + return {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} def test_dem_mechanism_counts_match( self, @@ -278,19 +278,19 @@ def test_sampling_statistics_match_stim( # Stim sampling - returns (det_events, obs_flips, error_data) stim_det_events, stim_obs_flips, _ = stim_sampler.sample(num_shots) stim_syndrome_count = np.any(stim_det_events, axis=1).sum() - stim_logical_count = np.any(stim_obs_flips, axis=1).sum() + stim_observable_count = np.any(stim_obs_flips, axis=1).sum() # Compare rates pecos_syndrome_rate = pecos_stats["syndrome_rate"] stim_syndrome_rate = stim_syndrome_count / num_shots pecos_logical_rate = pecos_stats["logical_error_rate"] - stim_logical_rate = stim_logical_count / num_shots + stim_logical_rate = stim_observable_count / num_shots # Compare absolute differences - allow up to 10% relative difference # Known: PECOS and Stim have slightly different DEM generation syndrome_diff = abs(pecos_syndrome_rate - stim_syndrome_rate) - logical_diff = abs(pecos_logical_rate - stim_logical_rate) + observable_diff = abs(pecos_logical_rate - stim_logical_rate) # Syndrome rates should be within 20% relative max_rate = max(pecos_syndrome_rate, stim_syndrome_rate, 0.001) @@ -301,11 +301,11 @@ def test_sampling_statistics_match_stim( ) # Logical error rates should be within 30% relative (more variable) - max_logical = max(pecos_logical_rate, stim_logical_rate, 0.001) - logical_rel_diff = logical_diff / max_logical - assert logical_rel_diff < 0.5, ( + max_observable = max(pecos_logical_rate, stim_logical_rate, 0.001) + observable_rel_diff = observable_diff / max_observable + assert observable_rel_diff < 0.5, ( f"Logical error rate mismatch: PECOS={pecos_logical_rate:.4f}, " - f"Stim={stim_logical_rate:.4f}, rel_diff={logical_rel_diff:.1%}" + f"Stim={stim_logical_rate:.4f}, rel_diff={observable_rel_diff:.1%}" ) def test_detector_firing_rates_correlate( @@ -386,7 +386,7 @@ def test_multi_round_d3_r3(self) -> None: patch = SurfacePatch.create(distance=3) tc = generate_tick_circuit_from_patch(patch, num_rounds=3, basis="Z") - noise_params = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_init": 0.01} + noise_params = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} # Build PECOS sampler dag = tc.to_dag_circuit() @@ -423,7 +423,7 @@ def test_multi_round_d3_r3(self) -> None: max_rate = max(pecos_stats["logical_error_rate"], stim_logical_rate, 0.001) rel_diff = abs(pecos_stats["logical_error_rate"] - stim_logical_rate) / max_rate assert rel_diff < 0.5, ( - f"Logical rate mismatch for d=3, r=3: " + f"Observable rate mismatch for d=3, r=3: " f"PECOS={pecos_stats['logical_error_rate']:.4f}, Stim={stim_logical_rate:.4f}, " f"rel_diff={rel_diff:.1%}" ) @@ -441,7 +441,7 @@ def test_logical_error_rate_scales(self, distance: int) -> None: patch = SurfacePatch.create(distance=distance) tc = generate_tick_circuit_from_patch(patch, num_rounds=1, basis="Z") - noise_params = {"p1": 0.001, "p2": 0.001, "p_meas": 0.001, "p_init": 0.001} + noise_params = {"p1": 0.001, "p2": 0.001, "p_meas": 0.001, "p_prep": 0.001} # Build sampler dag = tc.to_dag_circuit() @@ -482,7 +482,7 @@ def test_x_basis_dem_matches_stim(self) -> None: patch = SurfacePatch.create(distance=3) tc = generate_tick_circuit_from_patch(patch, num_rounds=1, basis="X") - noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_init": 0.01} + noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} # Generate DEMs (non-decomposed for exact comparison) pecos_dem = generate_dem_from_tick_circuit(tc, **noise, decompose_errors=False) @@ -531,7 +531,7 @@ def test_x_basis_sampling_matches_stim(self) -> None: patch = SurfacePatch.create(distance=3) tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="X") - noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_init": 0.01} + noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} # Build PECOS sampler dag = tc.to_dag_circuit() @@ -541,7 +541,9 @@ def test_x_basis_sampling_matches_stim(self) -> None: builder = DemSamplerBuilder(influence_map) builder.with_noise(**noise) builder.with_detectors_json(tc.get_meta("detectors") or "[]") - builder.with_observables_json(tc.get_meta("observables") or "[]") + builder.with_observables_json( + tc.get_meta("observables") or "[]" + ) builder.with_measurement_order(extract_measurement_order(tc)) pecos_sampler = builder.build() @@ -572,20 +574,20 @@ class TestAsymmetricNoise: @pytest.mark.parametrize( "noise_params", [ - {"p1": 0.001, "p2": 0.01, "p_meas": 0.005, "p_init": 0.002}, # p2 dominant - {"p1": 0.02, "p2": 0.001, "p_meas": 0.001, "p_init": 0.001}, # p1 dominant + {"p1": 0.001, "p2": 0.01, "p_meas": 0.005, "p_prep": 0.002}, # p2 dominant + {"p1": 0.02, "p2": 0.001, "p_meas": 0.001, "p_prep": 0.001}, # p1 dominant { "p1": 0.001, "p2": 0.001, "p_meas": 0.05, - "p_init": 0.001, + "p_prep": 0.001, }, # p_meas dominant { "p1": 0.001, "p2": 0.001, "p_meas": 0.001, - "p_init": 0.05, - }, # p_init dominant + "p_prep": 0.05, + }, # p_prep dominant ], ) def test_asymmetric_noise_dem_matches_stim( @@ -740,8 +742,8 @@ def _add_noise_to_stim( if name == "R": for t in targets: noisy.append("R", [t.value]) - if noise["p_init"] > 0: - noisy.append("X_ERROR", [t.value], noise["p_init"]) + if noise["p_prep"] > 0: + noisy.append("X_ERROR", [t.value], noise["p_prep"]) elif name in ("H", "S", "S_DAG"): for t in targets: noisy.append(name, [t.value]) @@ -823,7 +825,7 @@ def test_random_circuit_sampling_produces_valid_results(self, seed: int) -> None records = [-i for i in range(1, num_qubits + 1)] detectors_json = f'[{{"id": 0, "records": {records}}}]' - noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_init": 0.01} + noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} builder = DemSamplerBuilder(influence_map) builder.with_noise(**noise) @@ -864,7 +866,7 @@ def test_dem_exact_match(self, distance: int, num_rounds: int, basis: str) -> No patch = SurfacePatch.create(distance=distance) tc = generate_tick_circuit_from_patch(patch, num_rounds=num_rounds, basis=basis) - noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_init": 0.01} + noise = {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01} # Generate non-decomposed DEMs pecos_dem = generate_dem_from_tick_circuit(tc, **noise, decompose_errors=False) diff --git a/python/quantum-pecos/tests/qec/test_fault_catalog.py b/python/quantum-pecos/tests/qec/test_fault_catalog.py new file mode 100644 index 000000000..de2fba19b --- /dev/null +++ b/python/quantum-pecos/tests/qec/test_fault_catalog.py @@ -0,0 +1,422 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Tests for the fault_catalog() public API.""" + +import pytest + +from pecos.quantum import PauliString, TickCircuit +from pecos_rslib_exp import ( + FaultAlternative, + FaultCatalog, + FaultLocation, + depolarizing, + fault_catalog, +) + + +def build_h_mz(): + """H(0) MZ(0): single-qubit depolarizing.""" + tc = TickCircuit() + tc.tick().h([0]) + tick = tc.tick() + tick.mz([0]) + tc.set_meta("num_measurements", "1") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + return tc + + +def build_cx_mz(): + """CX(0,1) MZ(0) MZ(1): two-qubit depolarizing.""" + tc = TickCircuit() + tc.tick().cx([(0, 1)]) + tick = tc.tick() + tick.mz([0]) + tick = tc.tick() + tick.mz([1]) + tc.set_meta("num_measurements", "2") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + return tc + + +def pauli_terms(pauli): + """Return a {qubit: label} map from a PECOS PauliString.""" + return {q: str(p).split(".")[-1] for p, q in pauli.get_paulis()} + + +class TestFaultCatalogStructure: + def test_returns_fault_catalog(self): + tc = build_h_mz() + noise = depolarizing().p1(0.03).p2(0).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + assert isinstance(catalog, FaultCatalog) + assert isinstance(catalog.locations, list) + assert len(catalog) > 0 + assert isinstance(catalog[0], FaultLocation) + assert catalog[0] is catalog.locations[0] + + def test_fault_catalog_is_sequence_like(self): + tc = build_h_mz() + noise = depolarizing().p1(0.03).p2(0).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + assert len(list(catalog)) == len(catalog.locations) + assert catalog[-1] is catalog.locations[-1] + + def test_location_attributes(self): + tc = build_h_mz() + noise = depolarizing().p1(0.03).p2(0).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + loc = catalog[0] + assert hasattr(loc, "tick") + assert hasattr(loc, "gate_index") + assert hasattr(loc, "gate_type") + assert hasattr(loc, "qubits") + assert hasattr(loc, "channel_probability") + assert hasattr(loc, "faults") + + def test_fault_alternative_attributes(self): + tc = build_h_mz() + noise = depolarizing().p1(0.03).p2(0).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + fault = catalog[0].faults[0] + assert isinstance(fault, FaultAlternative) + assert hasattr(fault, "kind") + assert hasattr(fault, "pauli") + assert hasattr(fault, "detectors") + assert hasattr(fault, "observables") + assert hasattr(fault, "tracked_ops") + assert hasattr(fault, "measurements") + assert hasattr(fault, "conditional_probability") + assert hasattr(fault, "absolute_probability") + assert hasattr(fault, "channel_probability") + + +class TestPauliStringOutput: + def test_pauli_alternatives_are_pauli_string(self): + tc = build_h_mz() + noise = depolarizing().p1(0.03).p2(0).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + for loc in catalog: + for fault in loc.faults: + if fault.kind == "pauli": + assert isinstance(fault.pauli, PauliString), ( + f"Expected PauliString, got {type(fault.pauli)}" + ) + + def test_meas_prep_faults_have_none_pauli(self): + tc = TickCircuit() + tc.tick().pz([0]) + tick = tc.tick() + tick.mz([0]) + tc.set_meta("num_measurements", "1") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + + noise = depolarizing().p1(0).p2(0).p_meas(0.01).p_prep(0.01) + catalog = fault_catalog(tc, noise) + + for loc in catalog: + for fault in loc.faults: + if fault.kind in ("measurement_flip", "prep_flip"): + assert fault.pauli is None + + def test_two_qubit_pauli_has_two_terms(self): + tc = build_cx_mz() + noise = depolarizing().p1(0).p2(0.15).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + cx_loc = [l for l in catalog if l.gate_type == "CX"][0] + # At least some alternatives should have two Pauli terms (XX, XY, etc.) + two_term = [ + f for f in cx_loc.faults if len(f.pauli.get_paulis()) == 2 + ] + assert len(two_term) == 9, f"Expected 9 two-qubit Paulis, got {len(two_term)}" + + def test_new_gate_pauli_labels_and_measurement_effects(self): + tc = TickCircuit() + tc.tick().sx([0]) + tc.tick().szz([(0, 1)]) + tick = tc.tick() + tick.mz([0]) + tick.mz([1]) + tc.set_meta("num_measurements", "2") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + + noise = depolarizing().p1(0.03).p2(0.15).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + sx_loc = [l for l in catalog if l.gate_type == "SX"][0] + assert [pauli_terms(f.pauli) for f in sx_loc.faults] == [ + {0: "X"}, + {0: "Y"}, + {0: "Z"}, + ] + assert any(f.measurements for f in sx_loc.faults) + + szz_loc = [l for l in catalog if l.gate_type == "SZZ"][0] + assert len(szz_loc.faults) == 15 + observed = { + (terms.get(0, "I"), terms.get(1, "I")) + for terms in (pauli_terms(f.pauli) for f in szz_loc.faults) + } + expected = { + ("X", "I"), + ("Y", "I"), + ("Z", "I"), + ("I", "X"), + ("I", "Y"), + ("I", "Z"), + ("X", "X"), + ("X", "Y"), + ("X", "Z"), + ("Y", "X"), + ("Y", "Y"), + ("Y", "Z"), + ("Z", "X"), + ("Z", "Y"), + ("Z", "Z"), + } + assert observed == expected + assert any(f.measurements for f in szz_loc.faults) + + +class TestNoEffectLocationsIncluded: + def test_no_downstream_measurement_location_included(self): + """A gate with p1>0 but no MZ after it still appears in the catalog.""" + tc = TickCircuit() + tc.tick().h([0]) # No MZ follows — no measurement effect + tc.set_meta("num_measurements", "0") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + + noise = depolarizing().p1(0.01).p2(0).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + h_locs = [l for l in catalog if l.gate_type == "H"] + assert len(h_locs) == 1, "H with no downstream MZ should still appear" + assert len(h_locs[0].faults) == 3 + # All alternatives should have empty effects + for fault in h_locs[0].faults: + assert fault.measurements == [] + assert fault.detectors == [] + assert fault.observables == [] + assert abs(fault.absolute_probability - 0.01 / 3) < 1e-10 + + def test_prep_fault_with_no_effect_included(self): + """PZ followed by H then MZ: prep X → H → Z → no flip. Still in catalog.""" + tc = TickCircuit() + tc.tick().pz([0]) + tc.tick().h([0]) + tick = tc.tick() + tick.mz([0]) + tc.set_meta("num_measurements", "1") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + + noise = depolarizing().p1(0).p2(0).p_meas(0).p_prep(0.005) + catalog = fault_catalog(tc, noise) + + prep_locs = [l for l in catalog if any(f.kind == "prep_flip" for f in l.faults)] + assert len(prep_locs) == 1 + fault = prep_locs[0].faults[0] + assert fault.kind == "prep_flip" + assert fault.pauli is None + # Prep X through H becomes Z which doesn't flip MZ → empty + assert fault.measurements == [] + + +class TestProbabilities: + def test_single_qubit_location_fields(self): + tc = build_h_mz() + noise = depolarizing().p1(0.03).p2(0).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + h_loc = [l for l in catalog if l.gate_type == "H"][0] + assert h_loc.channel == "p1" + assert abs(h_loc.channel_probability - 0.03) < 1e-10 + assert abs(h_loc.no_fault_probability - 0.97) < 1e-10 + assert h_loc.num_alternatives == 3 + for fault in h_loc.faults: + assert abs(fault.conditional_probability - 1.0 / 3) < 1e-10 + assert abs(fault.absolute_probability - 0.01) < 1e-10 + + def test_two_qubit_location_fields(self): + tc = build_cx_mz() + noise = depolarizing().p1(0).p2(0.15).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + cx_loc = [l for l in catalog if l.gate_type == "CX"][0] + assert cx_loc.channel == "p2" + assert abs(cx_loc.channel_probability - 0.15) < 1e-10 + assert abs(cx_loc.no_fault_probability - 0.85) < 1e-10 + assert cx_loc.num_alternatives == 15 + for fault in cx_loc.faults: + assert abs(fault.conditional_probability - 1.0 / 15) < 1e-10 + assert abs(fault.absolute_probability - 0.01) < 1e-10 + + def test_full_configuration_probability(self): + """Compute one full-circuit event probability from catalog fields.""" + tc = build_h_mz() + noise = depolarizing().p1(0.03).p2(0).p_meas(0.01).p_prep(0) + catalog = fault_catalog(tc, noise) + + # Pick first alternative at H location, no fault at MZ location + h_loc = [l for l in catalog if l.channel == "p1"][0] + mz_loc = [l for l in catalog if l.channel == "p_meas"][0] + + # P(alt 0 at H, no fault at MZ) = (p1/3) * (1 - p_meas) + config_prob = h_loc.faults[0].absolute_probability * mz_loc.no_fault_probability + expected = (0.03 / 3) * (1 - 0.01) # 0.01 * 0.99 = 0.0099 + assert abs(config_prob - expected) < 1e-10 + + +class TestDetectorObservableMapping: + def test_detectors_are_lists(self): + tc = TickCircuit() + tc.tick().h([0]) + tc.tick().cx([(0, 1)]) + tc.tick().h([0]) + tick = tc.tick() + tick.mz([0]) + tick = tc.tick() + tick.mz([1]) + tc.set_meta("num_measurements", "2") + tc.set_meta("detectors", '[{"records": [-2, -1]}]') + tc.set_meta("observables", "[]") + + noise = depolarizing().p1(0.01).p2(0).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + has_det = any(f.detectors for loc in catalog for f in loc.faults) + assert has_det, "Some faults should fire detectors" + + for loc in catalog: + for fault in loc.faults: + assert isinstance(fault.detectors, list) + assert isinstance(fault.observables, list) + + +class TestFaultConfigurations: + def test_k0_one_no_fault_event(self): + tc = build_h_mz() + noise = depolarizing().p1(0.03).p2(0).p_meas(0.01).p_prep(0) + catalog = fault_catalog(tc, noise) + + configs = list(catalog.fault_configurations(0)) + assert len(configs) == 1 + c = configs[0] + assert c.location_indices == [] + assert c.alternative_indices == [] + assert c.measurements == [] + assert c.detectors == [] + assert c.observables == [] + assert c.selected_probability == 1.0 + # config_prob = product of all no_fault_probability + expected = 1.0 + for loc in catalog.locations: + expected *= loc.no_fault_probability + assert abs(c.configuration_probability - expected) < 1e-12 + + def test_k1_exposes_single_fault(self): + tc = build_h_mz() + noise = depolarizing().p1(0.03).p2(0).p_meas(0.01).p_prep(0) + catalog = fault_catalog(tc, noise) + + configs = list(catalog.fault_configurations(1)) + # Total = sum of num_alternatives + expected_count = sum(loc.num_alternatives for loc in catalog.locations) + assert len(configs) == expected_count + + # First config: location 0, alternative 0 + c = configs[0] + assert c.location_indices == [0] + assert c.alternative_indices == [0] + assert c.selected_probability > 0 + + def test_k2_xor_cancels_effects(self): + """Two faults flipping the same detector XOR-cancel.""" + tc = TickCircuit() + tc.tick().h([0]) + tc.tick().h([0]) + tick = tc.tick() + tick.mz([0]) + tc.set_meta("num_measurements", "1") + tc.set_meta("detectors", '[{"records":[-1]}]') + tc.set_meta("observables", "[]") + + noise = depolarizing().p1(0.03).p2(0).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + configs = list(catalog.fault_configurations(2)) + # Some configs should have empty detectors (XOR cancel) + cancelled = [c for c in configs if c.detectors == []] + assert len(cancelled) > 0 + + def test_k2_probability_hand_calc(self): + tc = build_h_mz() + noise = depolarizing().p1(0.03).p2(0).p_meas(0.01).p_prep(0) + catalog = fault_catalog(tc, noise) + # 2 locations: H(3 alts, p=0.03) and MZ(1 alt, p=0.01) + # k=2: both fire. selected = (0.03/3) * (0.01/1) = 0.0001 + # config = 0.0001 (no unselected locations) + + configs = list(catalog.fault_configurations(2)) + assert len(configs) == 3 # 3 H alternatives × 1 MZ alternative + for c in configs: + assert abs(c.selected_probability - 0.0001) < 1e-12 + assert abs(c.configuration_probability - 0.0001) < 1e-12 + + def test_returns_lazy_iterator_not_list(self): + tc = build_h_mz() + noise = depolarizing().p1(0.03).p2(0).p_meas(0.01).p_prep(0) + catalog = fault_catalog(tc, noise) + + it = catalog.fault_configurations(1) + assert not isinstance(it, list), "Should be a lazy iterator, not a list" + assert hasattr(it, "__next__"), "Should have __next__" + first = next(it) + assert hasattr(first, "location_indices") + assert hasattr(first, "locations") + assert hasattr(first, "faults") + assert hasattr(first, "tracked_ops") + + def test_yielded_locations_and_faults(self): + tc = build_h_mz() + noise = depolarizing().p1(0.03).p2(0).p_meas(0.01).p_prep(0) + catalog = fault_catalog(tc, noise) + + first = next(catalog.fault_configurations(1)) + # .locations should be the FaultLocation objects for selected indices + assert len(first.locations) == 1 + assert first.locations[0] is catalog.locations[first.location_indices[0]] + # .faults should be the FaultAlternative objects + assert len(first.faults) == 1 + loc = catalog.locations[first.location_indices[0]] + assert first.faults[0] is loc.faults[first.alternative_indices[0]] + + def test_tracked_ops_are_distinct_from_observables(self): + tc = TickCircuit() + tc.tick().h([0]) + tc.pauli_operator(PauliString.from_str("Z"), label="z_probe") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + + noise = depolarizing().p1(0.03).p2(0).p_meas(0).p_prep(0) + catalog = fault_catalog(tc, noise) + + h_loc = [loc for loc in catalog if loc.gate_type == "H"][0] + tracked = [fault.tracked_ops for fault in h_loc.faults] + assert tracked.count([0]) == 2 + assert tracked.count([]) == 1 + assert all(fault.observables == [] for fault in h_loc.faults) + + configs = list(catalog.fault_configurations(1)) + assert any(c.tracked_ops == [0] and c.observables == [] for c in configs) diff --git a/python/quantum-pecos/tests/qec/test_meas_sampling_backend.py b/python/quantum-pecos/tests/qec/test_meas_sampling_backend.py new file mode 100644 index 000000000..1224e7471 --- /dev/null +++ b/python/quantum-pecos/tests/qec/test_meas_sampling_backend.py @@ -0,0 +1,260 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Integration tests for meas_sampling() sim_neo backend. + +Tests the d=3 surface code 57/48 regression and method dispatch. +""" + +import json + +import pytest + +from pecos.qec.surface import SurfacePatch +from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model +from pecos_rslib_exp import dem_sampling, meas_sampling, depolarizing, sim_neo, stabilizer + + +@pytest.fixture +def d3_tc(): + patch = SurfacePatch.create(distance=3) + return _build_surface_tick_circuit_for_native_model(patch, 6, "Z", circuit_source="abstract") + + +@pytest.fixture +def depol(): + return depolarizing().p1(0.0005).p2(0.005).p_meas(0.005).p_prep(0.005) + + +@pytest.fixture +def coherent(): + return depolarizing().p1(0.0005).p2(0.005).p_meas(0.005).p_prep(0.005).idle_rz(0.05) + + +class TestD3SurfaceCode57vs48: + def test_raw_output_is_57_measurements(self, d3_tc, depol): + r = sim_neo(d3_tc).quantum(meas_sampling()).noise(depol).shots(10).seed(42).run() + assert len(r[0]) == 57 + + def test_nondet_measurement_mean_half(self, d3_tc, depol): + shots = 5000 + r = sim_neo(d3_tc).quantum(meas_sampling()).noise(depol).shots(shots).seed(42).run() + mean_0 = sum(s[0] for s in r) / shots + assert abs(mean_0 - 0.5) < 0.05, f"meas[0]={mean_0:.3f}" + + def test_det_measurement_mean_low(self, d3_tc, depol): + shots = 5000 + r = sim_neo(d3_tc).quantum(meas_sampling()).noise(depol).shots(shots).seed(42).run() + mean_4 = sum(s[4] for s in r) / shots + assert mean_4 < 0.1, f"meas[4]={mean_4:.3f}" + + def test_z_type_detection_rates_match_stabilizer(self, d3_tc, depol): + """Z-type detector rates match stabilizer (known-good subset).""" + shots = 10000 + det_json = json.loads(d3_tc.get_meta("detectors")) + num_meas = int(d3_tc.get_meta("num_measurements")) + num_dets = len(det_json) + + def rates(results): + r = [0.0] * num_dets + for shot in results: + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(shot): + val ^= shot[idx] + if val: + r[i] += 1.0 / len(results) + return r + + meas_r = sim_neo(d3_tc).quantum(meas_sampling()).noise(depol).shots(shots).seed(42).run() + stab_r = sim_neo(d3_tc).quantum(stabilizer()).noise(depol).shots(shots).seed(42).run() + + meas_rates = rates(meas_r) + stab_rates = rates(stab_r) + + # Z-type detectors (deterministic measurements) should match. + close_count = sum( + 1 for d, s in zip(meas_rates, stab_rates) + if s > 0.001 and abs(d - s) / s < 0.15 + ) + total_active = sum(1 for s in stab_rates if s > 0.001) + + # At least half the detectors should match (Z-type ones) + assert close_count >= total_active // 2, ( + f"Only {close_count}/{total_active} detectors within 15% of stabilizer." + ) + + def test_all_detection_rates_match_stabilizer(self, d3_tc, depol): + """ALL detector rates should match stabilizer (target correctness).""" + shots = 20000 + det_json = json.loads(d3_tc.get_meta("detectors")) + num_meas = int(d3_tc.get_meta("num_measurements")) + num_dets = len(det_json) + + def rates(results): + r = [0.0] * num_dets + for shot in results: + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(shot): + val ^= shot[idx] + if val: + r[i] += 1.0 / len(results) + return r + + meas_r = sim_neo(d3_tc).quantum(meas_sampling()).noise(depol).shots(shots).seed(42).run() + stab_r = sim_neo(d3_tc).quantum(stabilizer()).noise(depol).shots(shots).seed(42).run() + + meas_rates = rates(meas_r) + stab_rates = rates(stab_r) + + max_diff = max( + abs(d - s) / max(s, 1e-10) + for d, s in zip(meas_rates, stab_rates) + if s > 0.001 + ) + assert max_diff < 0.15, f"Max relative det rate diff: {max_diff:.1%}" + + def test_observable_flip_rates_match_stabilizer(self, d3_tc): + """Observable record extraction should match the stabilizer backend.""" + shots = 5000 + noise = depolarizing().p1(0.001).p2(0.01).p_meas(0.01).p_prep(0.01) + obs_json = json.loads(d3_tc.get_meta("observables") or "[]") + num_meas = int(d3_tc.get_meta("num_measurements")) + assert obs_json, "surface-code memory circuit should define observables" + + def rates(results): + r = [0.0] * len(obs_json) + for shot in results: + for i, obs in enumerate(obs_json): + val = 0 + for rec in obs["records"]: + idx = num_meas + rec + if 0 <= idx < len(shot): + val ^= shot[idx] + if val: + r[i] += 1.0 / len(results) + return r + + meas_r = sim_neo(d3_tc).quantum(meas_sampling()).noise(noise).shots(shots).seed(42).run() + stab_r = sim_neo(d3_tc).quantum(stabilizer()).noise(noise).shots(shots).seed(43).run() + + meas_rates = rates(meas_r) + stab_rates = rates(stab_r) + for i, (meas_rate, stab_rate) in enumerate(zip(meas_rates, stab_rates)): + abs_diff = abs(meas_rate - stab_rate) + rel_diff = abs_diff / max(stab_rate, 1e-12) + assert abs_diff < 0.03 or rel_diff < 0.5, ( + f"Observable L{i} rate mismatch: " + f"meas_sampling={meas_rate:.4f}, stabilizer={stab_rate:.4f}" + ) + + +class TestMethodDispatch: + def test_auto_no_idle_rz(self, d3_tc, depol): + r = sim_neo(d3_tc).quantum(meas_sampling("auto")).noise(depol).shots(10).seed(42).run() + assert len(r[0]) == 57 + + def test_auto_with_idle_rz(self, d3_tc, coherent): + r = sim_neo(d3_tc).quantum(meas_sampling("auto")).noise(coherent).shots(10).seed(42).run() + assert len(r[0]) == 57 + + def test_stochastic_rejects_idle_rz(self, d3_tc, coherent): + with pytest.raises(Exception, match="idle_rz"): + sim_neo(d3_tc).quantum(meas_sampling("stochastic")).noise(coherent).shots(10).seed(42).run() + + def test_coherent_no_idle_rz(self, d3_tc, depol): + r = sim_neo(d3_tc).quantum(meas_sampling("coherent")).noise(depol).shots(10).seed(42).run() + assert len(r[0]) == 57 + + def test_coherent_with_idle_rz(self, d3_tc, coherent): + r = sim_neo(d3_tc).quantum(meas_sampling("coherent")).noise(coherent).shots(10).seed(42).run() + assert len(r[0]) == 57 + + def test_invalid_method(self, d3_tc, depol): + with pytest.raises(Exception, match="Unknown"): + sim_neo(d3_tc).quantum(meas_sampling("bogus")).noise(depol).shots(10).seed(42).run() + + def test_no_noise_errors(self, d3_tc): + with pytest.raises(Exception, match="noise"): + sim_neo(d3_tc).quantum(meas_sampling()).shots(10).seed(42).run() + + +class TestDemSamplingApi: + def test_dem_sampling_builder_is_exported(self): + assert type(dem_sampling()).__name__ == "DemSamplingBuilder" + + def test_dem_sampling_runs(self, d3_tc, depol): + r = ( + sim_neo(d3_tc) + .quantum(dem_sampling()) + .noise(depol) + .shots(10) + .seed(42) + .run() + ) + assert len(r) == 10 + assert len(r[0]) == 57 + + def test_dem_sampling_matches_meas_sampling_stochastic_same_seed(self, d3_tc, depol): + dem_r = ( + sim_neo(d3_tc) + .quantum(dem_sampling("stochastic")) + .noise(depol) + .shots(25) + .seed(123) + .run() + ) + meas_r = ( + sim_neo(d3_tc) + .quantum(meas_sampling("stochastic")) + .noise(depol) + .shots(25) + .seed(123) + .run() + ) + + assert [dem_r[i] for i in range(len(dem_r))] == [ + meas_r[i] for i in range(len(meas_r)) + ] + + def test_dem_sampling_auto_with_idle_rz(self, d3_tc, coherent): + r = ( + sim_neo(d3_tc) + .quantum(dem_sampling("auto")) + .noise(coherent) + .shots(10) + .seed(42) + .run() + ) + assert len(r[0]) == 57 + + def test_dem_sampling_stochastic_rejects_idle_rz(self, d3_tc, coherent): + with pytest.raises(Exception, match="idle_rz"): + ( + sim_neo(d3_tc) + .quantum(dem_sampling("stochastic")) + .noise(coherent) + .shots(10) + .seed(42) + .run() + ) + + def test_dem_sampling_invalid_method(self, d3_tc, depol): + with pytest.raises(Exception, match="Unknown"): + ( + sim_neo(d3_tc) + .quantum(dem_sampling("bogus")) + .noise(depol) + .shots(10) + .seed(42) + .run() + ) + + def test_dem_sampling_no_noise_errors(self, d3_tc): + with pytest.raises(Exception, match="noise"): + sim_neo(d3_tc).quantum(dem_sampling()).shots(10).seed(42).run() diff --git a/python/quantum-pecos/tests/qec/test_meas_sampling_generality.py b/python/quantum-pecos/tests/qec/test_meas_sampling_generality.py new file mode 100644 index 000000000..f5ce6f1ed --- /dev/null +++ b/python/quantum-pecos/tests/qec/test_meas_sampling_generality.py @@ -0,0 +1,280 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Generality tests for meas_sampling() stochastic raw measurement backend. + +These test the core fault propagation and measurement sampling logic +on minimal hand-built circuits — not surface-code-specific. +""" + +import json + +import pytest + +from pecos.quantum import TickCircuit +from pecos_rslib_exp import meas_sampling, depolarizing, sim_neo, stabilizer, statevec + + +def build_two_round_x_check(): + """Minimal 2-round X-check: ancilla q0, data q1 q2.""" + tc = TickCircuit() + # Round 1 + tc.tick().h([0]) + tc.tick().cx([(0, 1)]) + tc.tick().cx([(0, 2)]) + tc.tick().h([0]) + tick = tc.tick() + tick.mz([0]) + tc.tick().pz([0]) + # Round 2 + tc.tick().h([0]) + tc.tick().cx([(0, 1)]) + tc.tick().cx([(0, 2)]) + tc.tick().h([0]) + tick = tc.tick() + tick.mz([0]) + + # Detector: m0 XOR m1 should be 0 in noiseless case + tc.set_meta("num_measurements", "2") + tc.set_meta("detectors", json.dumps([{"records": [-1, -2]}])) + tc.set_meta("observables", "[]") + return tc + + +def build_three_round_z_check(): + """3-round Z-check on single data qubit: ancilla q0, data q1.""" + tc = TickCircuit() + for _ in range(3): + tc.tick().pz([0]) + tc.tick().cx([(1, 0)]) # data is control for Z-check + tick = tc.tick() + tick.mz([0]) + + tc.set_meta("num_measurements", "3") + tc.set_meta("detectors", json.dumps([ + {"records": [-2, -3]}, # m0 XOR m1 + {"records": [-1, -2]}, # m1 XOR m2 + ])) + tc.set_meta("observables", "[]") + return tc + + +class TestMeasurementFaultIndependence: + """Measurement faults must not cancel through Copy chains.""" + + def test_two_round_meas_fault_both_fire(self): + """A detector comparing two Copy-linked measurements should see + faults from BOTH measurements independently.""" + tc = build_two_round_x_check() + # Measurement-only noise: each meas flips with p=0.01 + depol = depolarizing().p1(0).p2(0).p_meas(0.01).p_prep(0) + shots = 50000 + + meas_r = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(shots).seed(42).run() + stab_r = sim_neo(tc).quantum(stabilizer()).noise(depol).shots(shots).seed(42).run() + + # Extract detector rate + def det_rate(results): + return sum(s[0] ^ s[1] for s in results) / len(results) + + meas_rate = det_rate(meas_r) + stab_rate = det_rate(stab_r) + + # Expected: ~2*p_meas = 0.02 (two independent flips) + assert abs(meas_rate - stab_rate) / max(stab_rate, 1e-10) < 0.15, ( + f"Meas fault rate mismatch: dem={meas_rate:.4f} stab={stab_rate:.4f}" + ) + + +class TestPrepFaultAbsorption: + """Prep faults propagate forward but get absorbed at PZ/MZ.""" + + def test_prep_fault_reaches_next_measurement(self): + """A prep fault on PZ(ancilla) should flip the next ancilla MZ.""" + tc = build_two_round_x_check() + # Prep-only noise + depol = depolarizing().p1(0).p2(0).p_meas(0).p_prep(0.01) + shots = 50000 + + meas_r = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(shots).seed(42).run() + stab_r = sim_neo(tc).quantum(stabilizer()).noise(depol).shots(shots).seed(42).run() + + def det_rate(results): + return sum(s[0] ^ s[1] for s in results) / len(results) + + meas_rate = det_rate(meas_r) + stab_rate = det_rate(stab_r) + + # Prep faults fire the detector (X error → detected at MZ) + assert stab_rate > 0.005, f"Stabilizer should see prep faults: {stab_rate}" + assert abs(meas_rate - stab_rate) / stab_rate < 0.15, ( + f"Prep fault rate mismatch: dem={meas_rate:.4f} stab={stab_rate:.4f}" + ) + + def test_prep_fault_does_not_cross_reset(self): + """A prep fault should NOT propagate past a subsequent PZ on the same qubit.""" + tc = build_three_round_z_check() + depol = depolarizing().p1(0).p2(0).p_meas(0).p_prep(0.01) + shots = 50000 + + meas_r = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(shots).seed(42).run() + stab_r = sim_neo(tc).quantum(stabilizer()).noise(depol).shots(shots).seed(42).run() + + # Extract detector 0 (m0 XOR m1) rate + def det_rate(results, d): + num_meas = 3 + recs = [{"records": [-2, -3]}, {"records": [-1, -2]}][d]["records"] + fired = sum(1 for s in results + if sum(s[num_meas + r] for r in recs) % 2 == 1) + return fired / len(results) + + for d in [0, 1]: + meas_rate = det_rate(meas_r, d) + stab_rate = det_rate(stab_r, d) + assert abs(meas_rate - stab_rate) / max(stab_rate, 1e-10) < 0.20, ( + f"Det {d} prep fault mismatch: dem={meas_rate:.4f} stab={stab_rate:.4f}" + ) + + +class TestMultiRoundNonSurface: + """Multi-round circuits that are NOT surface codes.""" + + def test_three_round_z_check_all_noise(self): + """3-round Z-check with full depolarizing noise matches stabilizer.""" + tc = build_three_round_z_check() + depol = depolarizing().p1(0.001).p2(0.005).p_meas(0.005).p_prep(0.005) + shots = 50000 + + meas_r = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(shots).seed(42).run() + stab_r = sim_neo(tc).quantum(stabilizer()).noise(depol).shots(shots).seed(42).run() + + def det_rate(results, d): + num_meas = 3 + recs = [{"records": [-2, -3]}, {"records": [-1, -2]}][d]["records"] + fired = sum(1 for s in results + if sum(s[num_meas + r] for r in recs) % 2 == 1) + return fired / len(results) + + for d in [0, 1]: + meas_rate = det_rate(meas_r, d) + stab_rate = det_rate(stab_r, d) + assert abs(meas_rate - stab_rate) / max(stab_rate, 1e-10) < 0.15, ( + f"Det {d} mismatch: dem={meas_rate:.4f} stab={stab_rate:.4f}" + ) + + +class TestZeroNoise: + """With zero noise, all detectors must fire at rate 0.""" + + def test_two_round_x_check_zero_noise(self): + tc = build_two_round_x_check() + depol = depolarizing().p1(0).p2(0).p_meas(0).p_prep(0) + r = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(1000).seed(42).run() + det_fires = sum(s[0] ^ s[1] for s in r) + assert det_fires == 0, f"Zero-noise detector fired {det_fires}/1000 times" + + def test_three_round_z_check_zero_noise(self): + tc = build_three_round_z_check() + depol = depolarizing().p1(0).p2(0).p_meas(0).p_prep(0) + r = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(1000).seed(42).run() + for d in [0, 1]: + num_meas = 3 + recs = [{"records": [-2, -3]}, {"records": [-1, -2]}][d]["records"] + fired = sum(1 for s in r if sum(s[num_meas + r_] for r_ in recs) % 2 == 1) + assert fired == 0, f"Zero-noise det {d} fired {fired}/1000" + + def test_new_clifford_gates_match_stabilizer_zero_noise(self): + """meas_sampling and stabilizer agree exactly on a noiseless new-gate circuit.""" + tc = TickCircuit() + tc.tick().pz([0, 1, 2]) + tc.tick().x([0]) + tc.tick().cy([(0, 1)]) + tc.tick().szz([(1, 2)]) + tc.tick().swap([(1, 2)]) + tc.tick().sx([2]) + tc.tick().sxdg([2]) + tick = tc.tick() + tick.mz([0]) + tick.mz([1]) + tick.mz([2]) + tc.set_meta("num_measurements", "3") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + + depol = depolarizing().p1(0).p2(0).p_meas(0).p_prep(0) + shots = 32 + meas_r = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(shots).seed(11).run() + stab_r = sim_neo(tc).quantum(stabilizer()).noise(depol).shots(shots).seed(99).run() + + assert len(meas_r) == len(stab_r) == shots + for shot in range(shots): + assert list(meas_r[shot]) == list(stab_r[shot]) == [1, 0, 1] + + +class TestCYGateSupport: + """CY gate should work through the meas_sampling public path.""" + + def test_cy_sign_has_circuit_level_measurement_effect(self): + """CY maps XX to -YZ, so measuring YZ after CY gives odd parity.""" + tc = TickCircuit() + tc.tick().pz([0, 1]) + tc.tick().h([0]) + tc.tick().h([1]) + tc.tick().cy([(0, 1)]) + tc.tick().f([0]) + tick = tc.tick() + tick.mz([0]) + tick.mz([1]) + tc.set_meta("num_measurements", "2") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + + depol = depolarizing().p1(0).p2(0).p_meas(0).p_prep(0) + for backend in (stabilizer(), statevec()): + result = sim_neo(tc).quantum(backend).noise(depol).shots(32).seed(123).run() + for shot in range(result.num_shots): + row = list(result[shot]) + assert row[0] ^ row[1] == 1 + + def test_cy_circuit_shape_and_values(self): + """H(0) CY(0,1) MZ(0) MZ(1): 2 measurements, no unsupported-gate error.""" + tc = TickCircuit() + tc.tick().h([0]) + tc.tick().cy([(0, 1)]) + tick = tc.tick() + tick.mz([0]) + tick = tc.tick() + tick.mz([1]) + tc.set_meta("num_measurements", "2") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + + depol = depolarizing().p1(0.005).p2(0.005).p_meas(0.005).p_prep(0.005) + result = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(100).seed(42).run() + + assert len(result) == 100 + assert len(result[0]) == 2 + for shot in range(100): + for meas in range(2): + assert result.get(shot, meas) in (0, 1) + + def test_cy_matches_stabilizer_protocol(self): + """CY circuit: meas_sampling and stabilizer produce same output shape.""" + tc = TickCircuit() + tc.tick().h([0]) + tc.tick().cy([(0, 1)]) + tick = tc.tick() + tick.mz([0]) + tick = tc.tick() + tick.mz([1]) + tc.set_meta("num_measurements", "2") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + + depol = depolarizing().p1(0.005).p2(0.005).p_meas(0.005).p_prep(0.005) + + meas_r = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(100).seed(42).run() + stab_r = sim_neo(tc).quantum(stabilizer()).noise(depol).shots(100).seed(42).run() + + assert len(meas_r) == len(stab_r) == 100 + assert meas_r.num_measurements == stab_r.num_measurements == 2 diff --git a/python/quantum-pecos/tests/qec/test_raw_measurement_result.py b/python/quantum-pecos/tests/qec/test_raw_measurement_result.py new file mode 100644 index 000000000..7953b4d60 --- /dev/null +++ b/python/quantum-pecos/tests/qec/test_raw_measurement_result.py @@ -0,0 +1,191 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Tests proving RawMeasurementResult protocol compatibility across backends. + +All sim_neo backends now return RawMeasurementResult, a common Rust-backed +type that supports indexing, iteration, len(), and get(). This test verifies +the output contract is identical for stabilizer and meas_sampling. +""" + +import pytest + +from pecos.qec.surface import SurfacePatch +from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model +from pecos_rslib_exp import meas_sampling, depolarizing, sim_neo, stabilizer + + +@pytest.fixture +def d3_results(): + """Run both backends on the same circuit and return their results.""" + patch = SurfacePatch.create(distance=3) + tc = _build_surface_tick_circuit_for_native_model(patch, 6, "Z", circuit_source="abstract") + depol = depolarizing().p1(0.005).p2(0.005).p_meas(0.005).p_prep(0.005) + + stab_r = sim_neo(tc).quantum(stabilizer()).noise(depol).shots(100).seed(42).run() + meas_r = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(100).seed(42).run() + return stab_r, meas_r + + +class TestCommonProtocol: + """Both backends return objects with the same interface.""" + + def test_len(self, d3_results): + stab_r, meas_r = d3_results + assert len(stab_r) == 100 + assert len(meas_r) == 100 + + def test_indexing(self, d3_results): + stab_r, meas_r = d3_results + # r[shot] returns a sequence of u8 values + s0 = stab_r[0] + d0 = meas_r[0] + assert len(s0) == len(d0) == 57 # d=3 surface code has 57 measurements + + def test_item_values(self, d3_results): + stab_r, meas_r = d3_results + # Individual values are 0 or 1 + for val in stab_r[0]: + assert val in (0, 1) + for val in meas_r[0]: + assert val in (0, 1) + + def test_list_conversion(self, d3_results): + stab_r, meas_r = d3_results + s_row = list(stab_r[0]) + d_row = list(meas_r[0]) + assert all(isinstance(v, int) for v in s_row) + assert all(isinstance(v, int) for v in d_row) + assert len(s_row) == len(d_row) == 57 + + def test_iteration(self, d3_results): + stab_r, meas_r = d3_results + stab_count = 0 + for row in stab_r: + stab_count += 1 + assert len(row) == 57 + assert stab_count == 100 + + dem_count = 0 + for row in meas_r: + dem_count += 1 + assert len(row) == 57 + assert dem_count == 100 + + def test_out_of_range_raises_index_error(self, d3_results): + stab_r, meas_r = d3_results + with pytest.raises(IndexError): + stab_r[100] + with pytest.raises(IndexError): + meas_r[100] + + def test_num_shots_property(self, d3_results): + stab_r, meas_r = d3_results + assert stab_r.num_shots == 100 + assert meas_r.num_shots == 100 + + def test_num_measurements_property(self, d3_results): + stab_r, meas_r = d3_results + assert stab_r.num_measurements == 57 + assert meas_r.num_measurements == 57 + + def test_get_method(self, d3_results): + stab_r, meas_r = d3_results + # get(shot, meas) returns 0 or 1 + assert stab_r.get(0, 0) in (0, 1) + assert meas_r.get(0, 0) in (0, 1) + + def test_get_out_of_range(self, d3_results): + stab_r, meas_r = d3_results + with pytest.raises(IndexError): + stab_r.get(100, 0) + with pytest.raises(IndexError): + meas_r.get(0, 57) + + def test_get_shot_method(self, d3_results): + stab_r, meas_r = d3_results + s = stab_r.get_shot(0) + d = meas_r.get_shot(0) + assert len(s) == len(d) == 57 + + def test_to_list(self, d3_results): + stab_r, meas_r = d3_results + sl = stab_r.to_list() + dl = meas_r.to_list() + assert len(sl) == len(dl) == 100 + assert len(sl[0]) == len(dl[0]) == 57 + + def test_negative_index_raises_index_error(self, d3_results): + """Negative indexing raises IndexError, never OverflowError.""" + stab_r, meas_r = d3_results + with pytest.raises(IndexError): + stab_r[-1] + with pytest.raises(IndexError): + meas_r[-1] + + def test_negative_get_raises_index_error(self, d3_results): + stab_r, meas_r = d3_results + # Negative shot + with pytest.raises(IndexError): + stab_r.get(-1, 0) + with pytest.raises(IndexError): + meas_r.get(-1, 0) + # Negative measurement + with pytest.raises(IndexError): + stab_r.get(0, -1) + with pytest.raises(IndexError): + meas_r.get(0, -1) + + def test_get_shot_negative_raises_index_error(self, d3_results): + stab_r, meas_r = d3_results + with pytest.raises(IndexError): + stab_r.get_shot(-1) + with pytest.raises(IndexError): + meas_r.get_shot(-1) + + def test_out_of_range_uses_len(self, d3_results): + """result[len(result)] raises IndexError.""" + stab_r, meas_r = d3_results + with pytest.raises(IndexError): + stab_r[len(stab_r)] + with pytest.raises(IndexError): + meas_r[len(meas_r)] + + +class TestGenericConsumer: + """A generic helper that works unchanged for any backend.""" + + def compute_measurement_means(self, result): + """Compute per-measurement mean across all shots — works for any backend.""" + shots = len(result) + if shots == 0: + return [] + n_meas = len(result[0]) + means = [0.0] * n_meas + for row in result: + for i, val in enumerate(row): + means[i] += val + return [m / shots for m in means] + + def test_generic_consumer_stabilizer(self): + patch = SurfacePatch.create(distance=3) + tc = _build_surface_tick_circuit_for_native_model(patch, 6, "Z", circuit_source="abstract") + depol = depolarizing().p1(0.005).p2(0.005).p_meas(0.005).p_prep(0.005) + result = sim_neo(tc).quantum(stabilizer()).noise(depol).shots(1000).seed(42).run() + + means = self.compute_measurement_means(result) + assert len(means) == 57 + # Non-det measurements should be ~0.5, det should be ~0 + nondet = sum(1 for m in means if abs(m - 0.5) < 0.15) + assert nondet > 0 + + def test_generic_consumer_meas_sampling(self): + patch = SurfacePatch.create(distance=3) + tc = _build_surface_tick_circuit_for_native_model(patch, 6, "Z", circuit_source="abstract") + depol = depolarizing().p1(0.005).p2(0.005).p_meas(0.005).p_prep(0.005) + result = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(1000).seed(42).run() + + means = self.compute_measurement_means(result) + assert len(means) == 57 + nondet = sum(1 for m in means if abs(m - 0.5) < 0.15) + assert nondet > 0 diff --git a/python/quantum-pecos/tests/qec/test_sample_batch.py b/python/quantum-pecos/tests/qec/test_sample_batch.py new file mode 100644 index 000000000..812c3acb5 --- /dev/null +++ b/python/quantum-pecos/tests/qec/test_sample_batch.py @@ -0,0 +1,89 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Tests for SampleBatch columnar storage and validation.""" + +import pytest + +from pecos_rslib.qec import DemSampler, SampleBatch + + +class TestSampleBatchConstruction: + def test_round_trip_get_syndrome(self): + batch = SampleBatch([[1, 0], [0, 1]], [1, 0]) + assert list(batch.get_syndrome(0)) == [1, 0] + assert list(batch.get_syndrome(1)) == [0, 1] + + def test_round_trip_get_observable_mask(self): + batch = SampleBatch([[1, 0], [0, 1]], [1, 0]) + assert batch.get_observable_mask(0) == 1 + assert batch.get_observable_mask(1) == 0 + + def test_num_shots(self): + batch = SampleBatch([[0, 0], [1, 1], [0, 1]], [0, 0, 0]) + assert batch.num_shots == 3 + + def test_ragged_rows_longer_rejected(self): + with pytest.raises(ValueError, match="row 1.*length 3.*expected 2"): + SampleBatch([[1, 0], [0, 1, 1]], [0, 0]) + + def test_ragged_rows_shorter_rejected(self): + with pytest.raises(ValueError, match="row 2.*length 1.*expected 2"): + SampleBatch([[1, 0], [0, 1], [0]], [0, 0, 0]) + + def test_length_mismatch_rejected(self): + with pytest.raises(ValueError, match="must have same length"): + SampleBatch([[1, 0]], [0, 0]) + + def test_empty_batch(self): + batch = SampleBatch([], []) + assert batch.num_shots == 0 + + +class TestGeneratedSampleBatch: + @pytest.fixture + def d3_setup(self): + from pecos.qec.surface import SurfacePatch + from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model + + patch = SurfacePatch.create(distance=3) + tc = _build_surface_tick_circuit_for_native_model( + patch, 6, "Z", circuit_source="abstract" + ) + sampler = DemSampler.from_circuit( + tc, p1=0.005, p2=0.005, p_meas=0.005, p_prep=0.005 + ) + return sampler, tc + + def test_num_shots(self, d3_setup): + sampler, _ = d3_setup + batch = sampler.generate_samples(100, seed=42) + assert batch.num_shots == 100 + + def test_get_syndrome_shape(self, d3_setup): + sampler, _ = d3_setup + batch = sampler.generate_samples(10, seed=42) + syn = batch.get_syndrome(0) + assert len(syn) == sampler.num_detectors + + def test_get_observable_mask_type(self, d3_setup): + sampler, _ = d3_setup + batch = sampler.generate_samples(10, seed=42) + mask = batch.get_observable_mask(0) + assert isinstance(mask, int) + + def test_decode_count(self, d3_setup): + import stim + from pecos.qec.surface.circuit_builder import tick_circuit_to_stim + + sampler, tc = d3_setup + noise = dict(p1=0.005, p2=0.005, p_meas=0.005, p_prep=0.005) + stim_str = tick_circuit_to_stim(tc, **noise) + dem_str = str( + stim.Circuit(stim_str).detector_error_model(decompose_errors=True) + ) + + batch = sampler.generate_samples(1000, seed=42) + errors = batch.decode_count(dem_str, "pymatching") + assert isinstance(errors, int) + assert 0 <= errors <= 1000 diff --git a/python/quantum-pecos/tests/qec/test_traced_qis_clifford_pipeline.py b/python/quantum-pecos/tests/qec/test_traced_qis_clifford_pipeline.py new file mode 100644 index 000000000..ecb61c6cf --- /dev/null +++ b/python/quantum-pecos/tests/qec/test_traced_qis_clifford_pipeline.py @@ -0,0 +1,287 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Smoke tests for the traced-QIS surface-code route after Clifford lowering.""" + +import random + +from pecos.qec.surface import SurfacePatch +from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model +from pecos.quantum import TickCircuit +from pecos_rslib_exp import ( + Mast, + StabMps, + depolarizing, + fault_catalog, + meas_sampling, + sim_neo, + stabilizer, + statevec, +) + +ONE_Q_INVERSES = { + "X": "X", + "Y": "Y", + "Z": "Z", + "H": "H", + "F": "Fdg", + "Fdg": "F", + "SX": "SXdg", + "SXdg": "SX", + "SY": "SYdg", + "SYdg": "SY", + "SZ": "SZdg", + "SZdg": "SZ", +} + +TWO_Q_INVERSES = { + "CX": "CX", + "CY": "CY", + "CZ": "CZ", + "SXX": "SXXdg", + "SXXdg": "SXX", + "SYY": "SYYdg", + "SYYdg": "SYY", + "SZZ": "SZZdg", + "SZZdg": "SZZ", + "SWAP": "SWAP", +} + +TICK_1Q_METHODS = { + "X": "x", + "Y": "y", + "Z": "z", + "H": "h", + "F": "f", + "Fdg": "fdg", + "SX": "sx", + "SXdg": "sxdg", + "SY": "sy", + "SYdg": "sydg", + "SZ": "sz", + "SZdg": "szdg", +} + +TICK_2Q_METHODS = { + "CX": "cx", + "CY": "cy", + "CZ": "cz", + "SXX": "sxx", + "SXXdg": "sxxdg", + "SYY": "syy", + "SYYdg": "syydg", + "SZZ": "szz", + "SZZdg": "szzdg", + "SWAP": "swap", +} + + +def build_lowered_traced_qis_surface_code(rounds=3): + patch = SurfacePatch.create(distance=3) + tc = _build_surface_tick_circuit_for_native_model(patch, rounds, "Z", circuit_source="traced_qis") + tc.lower_clifford_rotations() + return tc + + +def traced_qis_noise(): + return depolarizing().p1(0.0003).p2(0.003).p_meas(0.0015).p_prep(0.0015) + + +def zero_noise(): + return depolarizing().p1(0).p2(0).p_meas(0).p_prep(0) + + +def build_explicit_clifford_gate_circuit(): + tc = TickCircuit() + tc.tick().szdg([0]) + tc.tick().sx([0]) + tc.tick().sxdg([1]) + tc.tick().sy([0]) + tc.tick().sydg([1]) + tc.tick().f([0]) + tc.tick().fdg([1]) + tc.tick().cy([(0, 1)]) + tc.tick().cz([(0, 1)]) + tc.tick().sxx([(0, 1)]) + tc.tick().sxxdg([(0, 1)]) + tc.tick().syy([(0, 1)]) + tc.tick().syydg([(0, 1)]) + tc.tick().szz([(0, 1)]) + tc.tick().szzdg([(0, 1)]) + tc.tick().swap([(0, 1)]) + tc.tick().mz([0, 1]) + tc.set_meta("num_measurements", "2") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + return tc + + +def random_standard_clifford_sequence(seed, depth=14, num_qubits=3): + rng = random.Random(seed) + sequence = [] + for _ in range(depth): + if rng.random() < 0.55: + gate = rng.choice(tuple(ONE_Q_INVERSES)) + qubits = (rng.randrange(num_qubits),) + else: + gate = rng.choice(tuple(TWO_Q_INVERSES)) + q0, q1 = rng.sample(range(num_qubits), 2) + qubits = (q0, q1) + sequence.append((gate, qubits)) + return sequence + + +def inverse_standard_clifford_sequence(sequence): + inverse = [] + for gate, qubits in reversed(sequence): + if len(qubits) == 1: + inverse.append((ONE_Q_INVERSES[gate], qubits)) + else: + inverse.append((TWO_Q_INVERSES[gate], qubits)) + return inverse + + +def apply_tick_gate(tc, gate, qubits): + tick = tc.tick() + if len(qubits) == 1: + getattr(tick, TICK_1Q_METHODS[gate])([qubits[0]]) + else: + getattr(tick, TICK_2Q_METHODS[gate])([(qubits[0], qubits[1])]) + + +def build_mirrored_random_clifford_circuit(seed, num_qubits=3): + sequence = random_standard_clifford_sequence(seed, num_qubits=num_qubits) + tc = TickCircuit() + tc.tick().pz(list(range(num_qubits))) + for gate, qubits in sequence + inverse_standard_clifford_sequence(sequence): + apply_tick_gate(tc, gate, qubits) + tc.tick().mz(list(range(num_qubits))) + tc.set_meta("num_measurements", str(num_qubits)) + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + return tc, sequence + + +def run_direct_wrapper_mirrored_circuit(sim, sequence, num_qubits=3): + for q in range(num_qubits): + sim.run_1q_gate("PZ", q) + + for gate, qubits in sequence + inverse_standard_clifford_sequence(sequence): + if len(qubits) == 1: + sim.run_1q_gate(gate, qubits[0]) + else: + sim.run_2q_gate(gate, qubits) + + return [sim.run_1q_gate("MZ", q) for q in range(num_qubits)] + + +def test_meas_sampling_runs_on_lowered_traced_qis_surface_code(): + tc = build_lowered_traced_qis_surface_code() + shots = 8 + + result = sim_neo(tc).quantum(meas_sampling()).noise(traced_qis_noise()).shots(shots).seed(123).run() + + assert result.num_shots == shots + assert result.num_measurements == int(tc.get_meta("num_measurements")) + assert len(result[0]) == result.num_measurements + + +def test_fault_catalog_builds_on_lowered_traced_qis_surface_code(): + tc = build_lowered_traced_qis_surface_code() + + catalog = fault_catalog(tc, traced_qis_noise()) + first = next(catalog.fault_configurations(1)) + + assert len(catalog) > 0 + assert len(first.locations) == 1 + assert len(first.faults) == 1 + assert first.locations[0] is catalog.locations[first.location_indices[0]] + + +def test_lowered_traced_qis_pipeline_sampling_and_catalog_smoke(): + tc = build_lowered_traced_qis_surface_code(rounds=2) + noise = traced_qis_noise() + + result = sim_neo(tc).quantum(meas_sampling()).noise(noise).shots(3).seed(321).run() + catalog = fault_catalog(tc, noise) + first_fault = next(catalog.fault_configurations(1)) + + assert result.num_shots == 3 + assert result.num_measurements == int(tc.get_meta("num_measurements")) + assert len(catalog) > 0 + assert len(first_fault.locations) == 1 + assert len(first_fault.faults) == 1 + + +def test_explicit_python_gate_names_map_to_rust_clifford_gates(): + tc = build_explicit_clifford_gate_circuit() + noise = depolarizing().p1(0.03).p2(0.15).p_meas(0).p_prep(0) + + result = sim_neo(tc).quantum(meas_sampling()).noise(noise).shots(3).seed(123).run() + assert result.num_shots == 3 + assert result.num_measurements == 2 + + catalog = fault_catalog(tc, noise) + assert sum(len(loc.faults) for loc in catalog) == 156 + + +def test_sim_neo_native_backends_accept_face_gates(): + tc = TickCircuit() + tc.tick().pz([0]) + tc.tick().f([0]) + tc.tick().fdg([0]) + tc.tick().mz([0]) + tc.set_meta("num_measurements", "1") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + + for backend in (stabilizer(), statevec()): + result = sim_neo(tc).quantum(backend).noise(zero_noise()).shots(2).seed(123).run() + assert result.num_measurements == 1 + assert all(result[shot][0] == 0 for shot in range(result.num_shots)) + + +def test_direct_exp_wrappers_accept_standard_clifford_names(): + for sim in (StabMps(2, seed=123), Mast(2, 1, seed=123)): + for gate in ("I", "X", "Y", "Z", "H", "F", "Fdg", "SX", "SXdg", "SY", "SYdg", "SZ", "SZdg"): + sim.run_1q_gate(gate, 0) + + for gate in ( + "CX", + "CY", + "CZ", + "SXX", + "SXXdg", + "SYY", + "SYYdg", + "SZZ", + "SZZdg", + "SWAP", + ): + sim.run_2q_gate(gate, (0, 1)) + + +def test_direct_exp_wrappers_face_inverse_is_deterministic(): + for sim in (StabMps(1, seed=123), Mast(1, 1, seed=123)): + sim.run_1q_gate("PZ", 0) + sim.run_1q_gate("F", 0) + sim.run_1q_gate("Fdg", 0) + assert sim.run_1q_gate("MZ", 0) == 0 + + +def test_random_mirrored_standard_clifford_circuits_match_across_backends(): + expected = [0, 0, 0] + + for seed in (7, 19, 41): + tc, sequence = build_mirrored_random_clifford_circuit(seed) + + backend_results = {} + for name, backend in (("stabilizer", stabilizer()), ("statevec", statevec())): + result = sim_neo(tc).quantum(backend).noise(zero_noise()).shots(4).seed(seed).run() + backend_results[name] = [list(row) for row in result.to_list()] + + backend_results["StabMps"] = [run_direct_wrapper_mirrored_circuit(StabMps(3, seed=seed), sequence)] + backend_results["Mast"] = [run_direct_wrapper_mirrored_circuit(Mast(3, 1, seed=seed), sequence)] + + for name, rows in backend_results.items(): + assert all(row == expected for row in rows), (seed, name, rows) diff --git a/python/quantum-pecos/tests/qec/test_traced_qis_slow_integration.py b/python/quantum-pecos/tests/qec/test_traced_qis_slow_integration.py new file mode 100644 index 000000000..4ef2c1d37 --- /dev/null +++ b/python/quantum-pecos/tests/qec/test_traced_qis_slow_integration.py @@ -0,0 +1,183 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Slow traced-QIS integration tests for the raw-measurement pipeline.""" + +import json +import math + +import numpy as np +import pytest + +from pecos.qec.surface import SurfacePatch +from pecos.qec.surface.circuit_builder import tick_circuit_to_stim +from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model +from pecos_rslib.qec import DemSampler +from pecos_rslib_exp import depolarizing, fault_catalog, meas_sampling, sim_neo + +pymatching = pytest.importorskip("pymatching") +stim = pytest.importorskip("stim") + +pytestmark = pytest.mark.slow + + +def _noise_args(error_rate=0.003): + return { + "p1": error_rate * 0.1, + "p2": error_rate, + "p_meas": error_rate * 0.5, + "p_prep": error_rate * 0.5, + } + + +def _depolarizing_noise(noise_args): + return ( + depolarizing() + .p1(noise_args["p1"]) + .p2(noise_args["p2"]) + .p_meas(noise_args["p_meas"]) + .p_prep(noise_args["p_prep"]) + ) + + +def _build_lowered_traced_qis_surface_code(distance, rounds, basis="Z"): + patch = SurfacePatch.create(distance=distance) + circuit = _build_surface_tick_circuit_for_native_model(patch, rounds, basis, circuit_source="traced_qis") + circuit.lower_clifford_rotations() + return circuit + + +def _pymatching_decoder(circuit, noise_args): + stim_str = tick_circuit_to_stim(circuit, **noise_args) + dem = stim.Circuit(stim_str).detector_error_model(decompose_errors=True) + return pymatching.Matching.from_detector_error_model(dem) + + +def _extract_observable_mask(row, observables, num_measurements): + mask = 0 + for obs_index, obs in enumerate(observables): + value = 0 + for rec in obs["records"]: + idx = num_measurements + rec + if 0 <= idx < len(row): + value ^= int(row[idx]) + if value: + mask |= 1 << obs_index + return mask + + +def _decode_raw_measurements(result, circuit, matching, shots): + detectors = json.loads(circuit.get_meta("detectors")) + observables = json.loads(circuit.get_meta("observables") or "[]") + num_measurements = int(circuit.get_meta("num_measurements")) + syndrome = np.zeros(len(detectors), dtype=np.uint8) + + errors = 0 + for shot_index in range(shots): + row = result[shot_index] + syndrome.fill(0) + + for det_index, det in enumerate(detectors): + value = 0 + for rec in det["records"]: + idx = num_measurements + rec + if 0 <= idx < len(row): + value ^= int(row[idx]) + syndrome[det_index] = value + + predicted = matching.decode(syndrome) + predicted_mask = sum(int(bit) << index for index, bit in enumerate(predicted)) + actual_mask = _extract_observable_mask(row, observables, num_measurements) + errors += predicted_mask != actual_mask + + return errors + + +def _decode_native_dem_samples(circuit, noise_args, matching, shots, seed): + sampler = DemSampler.from_circuit(circuit, **noise_args) + batch = sampler.generate_samples(shots, seed=seed) + syndrome = np.zeros(sampler.num_detectors, dtype=np.uint8) + + errors = 0 + for shot_index in range(shots): + sampled_syndrome = batch.get_syndrome(shot_index) + for det_index in range(sampler.num_detectors): + syndrome[det_index] = sampled_syndrome[det_index] + predicted = matching.decode(syndrome) + predicted_mask = sum(int(bit) << index for index, bit in enumerate(predicted)) + errors += predicted_mask != batch.get_observable_mask(shot_index) + + return errors + + +def _assert_statistically_consistent(meas_errors, native_errors, shots): + meas_ler = meas_errors / shots + native_ler = native_errors / shots + pooled = (meas_errors + native_errors) / (2 * shots) + variance = 2 * max(pooled * (1 - pooled), 1 / shots) / shots + tolerance = max(0.04, 7 * math.sqrt(variance)) + + assert abs(meas_ler - native_ler) <= tolerance, ( + "meas_sampling and native DEM LERs differ more than stochastic tolerance: " + f"meas={meas_errors}/{shots} ({meas_ler:.4f}), " + f"native={native_errors}/{shots} ({native_ler:.4f}), " + f"tolerance={tolerance:.4f}" + ) + + +@pytest.mark.parametrize( + ("distance", "rounds", "shots"), + [ + (3, 6, 2_500), + (5, 10, 2_500), + ], +) +def test_traced_qis_meas_sampling_ler_tracks_native_dem_pymatching(distance, rounds, shots): + noise_args = _noise_args() + circuit = _build_lowered_traced_qis_surface_code(distance, rounds) + matching = _pymatching_decoder(circuit, noise_args) + + raw_result = ( + sim_neo(circuit).quantum(meas_sampling()).noise(_depolarizing_noise(noise_args)).shots(shots).seed(1234).run() + ) + meas_errors = _decode_raw_measurements(raw_result, circuit, matching, shots) + native_errors = _decode_native_dem_samples(circuit, noise_args, matching, shots, seed=5678) + + assert 0 <= meas_errors <= shots + assert 0 <= native_errors <= shots + _assert_statistically_consistent(meas_errors, native_errors, shots) + + +def test_d3_traced_qis_zero_noise_pymatching_pipeline_has_no_logical_errors(): + noise_args = _noise_args(error_rate=0.0) + circuit = _build_lowered_traced_qis_surface_code(distance=3, rounds=3) + matching = _pymatching_decoder(circuit, noise_args) + shots = 64 + + raw_result = ( + sim_neo(circuit).quantum(meas_sampling()).noise(_depolarizing_noise(noise_args)).shots(shots).seed(2468).run() + ) + meas_errors = _decode_raw_measurements(raw_result, circuit, matching, shots) + native_errors = _decode_native_dem_samples(circuit, noise_args, matching, shots, seed=1357) + + assert meas_errors == 0 + assert native_errors == 0 + + +def test_d3_traced_qis_fault_catalog_builds_with_all_noise_channels_enabled(): + noise_args = _noise_args() + circuit = _build_lowered_traced_qis_surface_code(distance=3, rounds=9) + catalog = fault_catalog(circuit, _depolarizing_noise(noise_args)) + + alternative_counts = [len(location.faults) for location in catalog] + assert len(catalog) > 100 + assert 1 in alternative_counts + assert 3 in alternative_counts + assert 15 in alternative_counts + assert sum(alternative_counts) > 1_000 + + first_event = next(catalog.fault_configurations(1)) + assert len(first_event.locations) == 1 + assert len(first_event.faults) == 1 + assert first_event.locations[0] is catalog.locations[first_event.location_indices[0]] + assert first_event.faults[0] is first_event.locations[0].faults[first_event.alternative_indices[0]] diff --git a/python/quantum-pecos/tests/slr-tests/pytest.ini b/python/quantum-pecos/tests/slr-tests/pytest.ini index 8002642ab..854bc91f0 100644 --- a/python/quantum-pecos/tests/slr-tests/pytest.ini +++ b/python/quantum-pecos/tests/slr-tests/pytest.ini @@ -12,8 +12,6 @@ markers = # slow: mark test as slow. optional_dependency: mark a test as using one or more optional dependencies. optional_unix: mark tests as using an optional dependency that only work with Unix-based systems. - wasmer: mark test as using the "wasmer" option. - wasmtime: mark test as using the "wasmtime" option. # Ignore various deprecation warnings filterwarnings = diff --git a/python/selene-plugins/pecos-selene-mast/Cargo.toml b/python/selene-plugins/pecos-selene-mast/Cargo.toml new file mode 100644 index 000000000..2f14e16cb --- /dev/null +++ b/python/selene-plugins/pecos-selene-mast/Cargo.toml @@ -0,0 +1,24 @@ +[package] +name = "pecos-selene-mast" +version.workspace = true +edition.workspace = true +license.workspace = true +repository.workspace = true +keywords.workspace = true +categories.workspace = true +description = "PECOS Mast (magic state injection) simulator plugin for the Selene quantum emulator" + +[lib] +name = "pecos_selene_mast" +path = "src/lib.rs" +crate-type = ["cdylib"] + +[dependencies] +anyhow = { workspace = true } +pecos-core = { workspace = true } +pecos-simulators = { workspace = true } +pecos-stab-tn = { path = "../../../exp/pecos-stab-tn" } +selene-core = { git = "https://github.com/Quantinuum/selene.git", rev = "1794e8d1dba26120a18e904940c014f4e034bed6" } + +[lints] +workspace = true diff --git a/python/selene-plugins/pecos-selene-mast/README.md b/python/selene-plugins/pecos-selene-mast/README.md new file mode 100644 index 000000000..d77706510 --- /dev/null +++ b/python/selene-plugins/pecos-selene-mast/README.md @@ -0,0 +1,13 @@ +# pecos-selene-mast + +PECOS Mast (magic state injection) simulator plugin for the Selene quantum emulator. + +Handles non-Clifford gates via deferred ancilla projection. Bond dimension stays bounded for Clifford+T circuits. + +## Usage + +```python +from pecos_selene_mast import MastPlugin + +sim = MastPlugin() +``` diff --git a/python/selene-plugins/pecos-selene-clifford-rz/hatch_build.py b/python/selene-plugins/pecos-selene-mast/hatch_build.py similarity index 93% rename from python/selene-plugins/pecos-selene-clifford-rz/hatch_build.py rename to python/selene-plugins/pecos-selene-mast/hatch_build.py index 46f331705..4ec910348 100644 --- a/python/selene-plugins/pecos-selene-clifford-rz/hatch_build.py +++ b/python/selene-plugins/pecos-selene-mast/hatch_build.py @@ -25,7 +25,7 @@ from packaging.tags import sys_tags -class PecosSeleneCliffordRzBuildHook(BuildHookInterface): +class PecosSeleneMastBuildHook(BuildHookInterface): """Build hook that compiles the Rust plugin and copies it to the Python package.""" def _set_wheel_tag(self, build_data: dict[str, Any]) -> None: @@ -60,7 +60,7 @@ def initialize( # Check if library already exists (e.g., from `make build-selene`) # If so, skip building and just collect artifacts - dist_dir = root / "python" / "pecos_selene_clifford_rz" / "_dist" + dist_dir = root / "python" / "pecos_selene_mast" / "_dist" lib_dir = dist_dir / "lib" if lib_dir.exists() and any(lib_dir.iterdir()): self.app.display_info("Library already built, skipping cargo build...") @@ -93,8 +93,8 @@ def initialize( msg = f"Unsupported platform: {system}" raise RuntimeError(msg) - lib_name = "pecos_selene_clifford_rz" - cargo_package = "pecos-selene-clifford-rz" + lib_name = "pecos_selene_mast" + cargo_package = "pecos-selene-mast" self.app.display_info(f"Building {cargo_package}...") @@ -130,7 +130,7 @@ def initialize( raise RuntimeError(msg) # Copy to the _dist/lib directory in the Python package - dest_dir = root / "python" / "pecos_selene_clifford_rz" / "_dist" / "lib" + dest_dir = root / "python" / "pecos_selene_mast" / "_dist" / "lib" dest_dir.mkdir(parents=True, exist_ok=True) dest_lib = dest_dir / lib_filename @@ -139,7 +139,7 @@ def initialize( # Collect artifacts artifacts = [] - dist_dir = root / "python" / "pecos_selene_clifford_rz" / "_dist" + dist_dir = root / "python" / "pecos_selene_mast" / "_dist" for artifact in dist_dir.rglob("*"): if artifact.is_file(): rel_path = artifact.relative_to(root) diff --git a/python/selene-plugins/pecos-selene-mast/pyproject.toml b/python/selene-plugins/pecos-selene-mast/pyproject.toml new file mode 100644 index 000000000..7f122af63 --- /dev/null +++ b/python/selene-plugins/pecos-selene-mast/pyproject.toml @@ -0,0 +1,36 @@ +[project] +name = "pecos-selene-mast" +version = "0.8.0.dev8" +requires-python = ">=3.10" +description = "PECOS Mast simulator plugin for the Selene quantum emulator" +license = "Apache-2.0" +dependencies = [ + "selene-core>=0.2", +] + +[project.optional-dependencies] +test = [ + "pytest>=9.0", + "selene-sim>=0.2", + "guppylang>=0.14", +] + +[project.urls] +homepage = "https://pecos.io" +repository = "https://github.com/PECOS-packages/PECOS" + +[build-system] +requires = ["hatchling", "packaging"] +build-backend = "hatchling.build" + +[tool.hatch.build.targets.wheel] +packages = ["python/pecos_selene_mast"] + +[tool.hatch.build.hooks.custom] +path = "hatch_build.py" + +[tool.uv] +cache-keys = [ + { file = "src/**/*.rs" }, + { file = "Cargo.toml" }, +] diff --git a/python/selene-plugins/pecos-selene-clifford-rz/python/pecos_selene_clifford_rz/__init__.py b/python/selene-plugins/pecos-selene-mast/python/pecos_selene_mast/__init__.py similarity index 81% rename from python/selene-plugins/pecos-selene-clifford-rz/python/pecos_selene_clifford_rz/__init__.py rename to python/selene-plugins/pecos-selene-mast/python/pecos_selene_mast/__init__.py index 0eaef3fdd..9beb3c930 100644 --- a/python/selene-plugins/pecos-selene-clifford-rz/python/pecos_selene_clifford_rz/__init__.py +++ b/python/selene-plugins/pecos-selene-mast/python/pecos_selene_mast/__init__.py @@ -10,8 +10,8 @@ # or implied. See the License for the specific language governing permissions and limitations under # the License. -"""PECOS CliffordRz Selene plugin.""" +"""PECOS Mast Selene plugin.""" -from pecos_selene_clifford_rz.plugin import CliffordRzPlugin +from pecos_selene_mast.plugin import MastPlugin -__all__ = ["CliffordRzPlugin"] +__all__ = ["MastPlugin"] diff --git a/python/selene-plugins/pecos-selene-mast/python/pecos_selene_mast/plugin.py b/python/selene-plugins/pecos-selene-mast/python/pecos_selene_mast/plugin.py new file mode 100644 index 000000000..662ce3443 --- /dev/null +++ b/python/selene-plugins/pecos-selene-mast/python/pecos_selene_mast/plugin.py @@ -0,0 +1,83 @@ +# Copyright 2026 The PECOS Developers +# +# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +# in compliance with the License. You may obtain a copy of the License at +# +# https://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software distributed under the License +# is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +# or implied. See the License for the specific language governing permissions and limitations under +# the License. + +"""PECOS Mast plugin for Selene.""" + +import platform +from dataclasses import dataclass +from pathlib import Path + +from selene_core import Simulator + + +@dataclass +class MastPlugin(Simulator): + """PECOS Mast (stabilizer+MPS) simulator plugin for Selene. + + This plugin provides a Mast (stabilizer+MPS) simulator backend for Selene using a + magic state injection decomposition. Clifford gates are applied efficiently, + while bond dimension stays bounded for Clifford+T circuits. + + Cost is polynomial in qubits and Clifford gates, exponential in the number + of RZ gates applied. + + Parameters + ---------- + random_seed : int, optional + Seed for the random number generator. If not provided, the seed + will be determined by Selene's shot management. + """ + + random_seed: int | None = None + + def get_init_args(self) -> list[str]: + """Return the initialization arguments for the Rust plugin. + + Returns: + ------- + list[str] + Empty list as Mast plugin doesn't require additional arguments. + """ + return [] + + @property + def library_file(self) -> Path: + """Return the path to the compiled Rust library. + + Returns: + ------- + Path + Path to the shared library file. + + Raises: + ------ + FileNotFoundError + If no matching library file is found. + """ + libdir = Path(__file__).parent / "_dist" / "lib" + + # Platform-specific library naming + system = platform.system().lower() + if system == "darwin": + patterns = ["libpecos_selene_mast*.dylib"] + elif system == "windows": + patterns = ["pecos_selene_mast*.dll", "pecos_selene_mast*.pyd"] + else: # Linux and others + patterns = ["libpecos_selene_mast*.so"] + + for pattern in patterns: + matches = list(libdir.glob(pattern)) + if matches: + return matches[0] + + msg = f"Could not find PECOS Mast library in {libdir}" + raise FileNotFoundError(msg) diff --git a/python/selene-plugins/pecos-selene-mast/src/lib.rs b/python/selene-plugins/pecos-selene-mast/src/lib.rs new file mode 100644 index 000000000..4e43f518f --- /dev/null +++ b/python/selene-plugins/pecos-selene-mast/src/lib.rs @@ -0,0 +1,213 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! PECOS `Mast` (Magic State injection) simulator plugin for the Selene quantum emulator. +//! +//! Wraps the MAST simulator which handles non-Clifford gates via deferred ancilla +//! projection. Bond dimension stays bounded for Clifford+T circuits. + +use anyhow::{Result, anyhow, bail}; +use pecos_core::{Angle64, QubitId}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable}; +use pecos_stab_tn::stab_mps::mast::Mast; +use selene_core::export_simulator_plugin; +use selene_core::simulator::SimulatorInterface; +use selene_core::simulator::interface::SimulatorInterfaceFactory; +use selene_core::utils::MetricValue; +use std::sync::Arc; + +pub struct MastSimulator { + simulator: Mast, + n_qubits: u64, + max_non_clifford: usize, +} + +impl MastSimulator { + #[allow(clippy::cast_possible_truncation)] + #[inline] + const fn to_usize(value: u64) -> usize { + value as usize + } +} + +impl SimulatorInterface for MastSimulator { + fn exit(&mut self) -> Result<()> { + Ok(()) + } + + fn shot_start(&mut self, _shot_id: u64, seed: u64) -> Result<()> { + self.simulator = + Mast::with_seed(Self::to_usize(self.n_qubits), self.max_non_clifford, seed); + Ok(()) + } + + fn shot_end(&mut self) -> Result<()> { + Ok(()) + } + + fn rxy(&mut self, qubit: u64, theta: f64, phi: f64) -> Result<()> { + if qubit >= self.n_qubits { + return Err(anyhow!( + "RXY(qubit={qubit}) out of bounds (n_qubits={})", + self.n_qubits + )); + } + let q = QubitId(Self::to_usize(qubit)); + self.simulator + .rz(Angle64::from_radians(-phi), &[q]) + .rx(Angle64::from_radians(theta), &[q]) + .rz(Angle64::from_radians(phi), &[q]); + Ok(()) + } + + fn rz(&mut self, qubit: u64, theta: f64) -> Result<()> { + if qubit >= self.n_qubits { + return Err(anyhow!( + "RZ(qubit={qubit}) out of bounds (n_qubits={})", + self.n_qubits + )); + } + self.simulator.rz( + Angle64::from_radians(theta), + &[QubitId(Self::to_usize(qubit))], + ); + Ok(()) + } + + fn rzz(&mut self, qubit1: u64, qubit2: u64, theta: f64) -> Result<()> { + if qubit1 >= self.n_qubits || qubit2 >= self.n_qubits { + return Err(anyhow!( + "RZZ(qubit1={qubit1}, qubit2={qubit2}) out of bounds (n_qubits={})", + self.n_qubits + )); + } + self.simulator.rzz( + Angle64::from_radians(theta), + &[( + QubitId(Self::to_usize(qubit1)), + QubitId(Self::to_usize(qubit2)), + )], + ); + Ok(()) + } + + fn measure(&mut self, qubit: u64) -> Result { + if qubit >= self.n_qubits { + return Err(anyhow!( + "Measure(qubit={qubit}) out of bounds (n_qubits={})", + self.n_qubits + )); + } + let results = self.simulator.mz(&[QubitId(Self::to_usize(qubit))]); + Ok(results[0].outcome) + } + + fn postselect(&mut self, qubit: u64, target_value: bool) -> Result<()> { + if qubit >= self.n_qubits { + return Err(anyhow!( + "Postselect(qubit={qubit}) out of bounds (n_qubits={})", + self.n_qubits + )); + } + let results = self.simulator.mz(&[QubitId(Self::to_usize(qubit))]); + if results[0].outcome != target_value { + return Err(anyhow!( + "Postselect(qubit={qubit}, target={target_value}) failed: got {}", + results[0].outcome + )); + } + Ok(()) + } + + fn reset(&mut self, qubit: u64) -> Result<()> { + if qubit >= self.n_qubits { + return Err(anyhow!( + "Reset(qubit={qubit}) out of bounds (n_qubits={})", + self.n_qubits + )); + } + let q = QubitId(Self::to_usize(qubit)); + let results = self.simulator.mz(&[q]); + if results[0].outcome { + self.simulator.x(&[q]); + } + Ok(()) + } + + fn get_metric(&mut self, nth_metric: u8) -> Result> { + match nth_metric { + 0 => Ok(Some(( + "max_bond_dim".to_string(), + MetricValue::U64(self.simulator.max_bond_dim() as u64), + ))), + 1 => Ok(Some(( + "num_ancillas_used".to_string(), + MetricValue::U64(self.simulator.num_ancillas_used() as u64), + ))), + _ => Ok(None), + } + } + + fn dump_state(&mut self, _file: &std::path::Path, _qubits: &[u64]) -> Result<()> { + Err(anyhow!("State dumping not supported for Mast")) + } +} + +#[derive(Default)] +pub struct MastSimulatorFactory; + +impl SimulatorInterfaceFactory for MastSimulatorFactory { + type Interface = MastSimulator; + + fn init( + self: Arc, + n_qubits: u64, + args: &[impl AsRef], + ) -> Result> { + let args: Vec = args.iter().map(|s| s.as_ref().to_string()).collect(); + // Optional arg: max_non_clifford (default 100) + let max_nc = if args.len() > 1 { + args[1].parse::().map_err(|_| { + anyhow!( + "Mast plugin expects optional integer argument max_non_clifford, got '{}'", + args[1] + ) + })? + } else { + 100 + }; + if n_qubits == 0 { + bail!("Number of qubits must be greater than 0"); + } + Ok(Box::new(MastSimulator { + simulator: Mast::with_seed(MastSimulator::to_usize(n_qubits), max_nc, 0), + n_qubits, + max_non_clifford: max_nc, + })) + } +} + +export_simulator_plugin!(crate::MastSimulatorFactory); + +#[cfg(test)] +mod tests { + use super::MastSimulatorFactory; + use selene_core::simulator::conformance_testing::run_basic_tests; + use std::sync::Arc; + + #[test] + fn basic_conformance_test() { + let interface = Arc::new(MastSimulatorFactory); + let args: Vec = vec![String::new()]; + run_basic_tests(interface, args); + } +} diff --git a/python/selene-plugins/pecos-selene-stab-mps/Cargo.toml b/python/selene-plugins/pecos-selene-stab-mps/Cargo.toml new file mode 100644 index 000000000..ea91374eb --- /dev/null +++ b/python/selene-plugins/pecos-selene-stab-mps/Cargo.toml @@ -0,0 +1,24 @@ +[package] +name = "pecos-selene-stab-mps" +version.workspace = true +edition.workspace = true +license.workspace = true +repository.workspace = true +keywords.workspace = true +categories.workspace = true +description = "PECOS StabMps simulator plugin for the Selene quantum emulator" + +[lib] +name = "pecos_selene_stab_mps" +path = "src/lib.rs" +crate-type = ["cdylib"] + +[dependencies] +anyhow = { workspace = true } +pecos-core = { workspace = true } +pecos-simulators = { workspace = true } +pecos-stab-tn = { path = "../../../exp/pecos-stab-tn" } +selene-core = { git = "https://github.com/Quantinuum/selene.git", rev = "1794e8d1dba26120a18e904940c014f4e034bed6" } + +[lints] +workspace = true diff --git a/python/selene-plugins/pecos-selene-stab-mps/README.md b/python/selene-plugins/pecos-selene-stab-mps/README.md new file mode 100644 index 000000000..9d919dfd1 --- /dev/null +++ b/python/selene-plugins/pecos-selene-stab-mps/README.md @@ -0,0 +1,13 @@ +# pecos-selene-stab-mps + +PECOS StabMps (stabilizer tableau + MPS) simulator plugin for the Selene quantum emulator. + +Stabilizer gates are O(n) on the tableau; non-Clifford rotations decompose in the stabilizer basis and apply to the MPS. Cost is polynomial when non-Clifford count is bounded. + +## Usage + +```python +from pecos_selene_stab_mps import StabMpsPlugin + +sim = StabMpsPlugin() +``` diff --git a/python/selene-plugins/pecos-selene-stab-mps/hatch_build.py b/python/selene-plugins/pecos-selene-stab-mps/hatch_build.py new file mode 100644 index 000000000..8a0e0f2f8 --- /dev/null +++ b/python/selene-plugins/pecos-selene-stab-mps/hatch_build.py @@ -0,0 +1,153 @@ +# Copyright 2026 The PECOS Developers +# +# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +# in compliance with the License. You may obtain a copy of the License at +# +# https://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software distributed under the License +# is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +# or implied. See the License for the specific language governing permissions and limitations under +# the License. + +"""Custom hatch build hook to compile and include the Rust shared library.""" + +from __future__ import annotations + +import platform +import shutil +import subprocess +import sys +from pathlib import Path +from typing import Any + +from hatchling.builders.hooks.plugin.interface import BuildHookInterface +from packaging.tags import sys_tags + + +class PecosSeleneStabMpsBuildHook(BuildHookInterface): + """Build hook that compiles the Rust plugin and copies it to the Python package.""" + + def _set_wheel_tag(self, build_data: dict[str, Any]) -> None: + """Set platform-specific wheel tags. + + This ensures the wheel is marked as platform-specific (not pure Python). + We use py3-none-{platform} since we don't bind to Python ABI directly. + """ + build_data["pure_python"] = False + + # Get the appropriate platform tag + tag = next( + iter(t for t in sys_tags() if "manylinux" not in t.platform and "musllinux" not in t.platform), + ) + target_platform = tag.platform + if sys.platform == "darwin": + from hatchling.builders.macos import process_macos_plat_tag + + target_platform = process_macos_plat_tag(target_platform, compat=False) + build_data["tag"] = f"py3-none-{target_platform}" + + self.app.display_info(f"Wheel tag: {build_data['tag']}") + + def initialize( + self, + version: str, + build_data: dict[str, Any], + ) -> None: + """Build the Rust library and include it as an artifact.""" + # Get the root directory (where pyproject.toml is) + root = Path(self.root) + + # Check if library already exists (e.g., from `make build-selene`) + # If so, skip building and just collect artifacts + dist_dir = root / "python" / "pecos_selene_stab_mps" / "_dist" + lib_dir = dist_dir / "lib" + if lib_dir.exists() and any(lib_dir.iterdir()): + self.app.display_info("Library already built, skipping cargo build...") + # Collect artifacts + artifacts = [] + for artifact in dist_dir.rglob("*"): + if artifact.is_file(): + rel_path = artifact.relative_to(root) + artifacts.append(str(rel_path.as_posix())) + if artifacts: + self.app.display_info("Found existing artifacts:") + for a in artifacts: + self.app.display_info(f" {a}") + build_data["artifacts"] += artifacts + self._set_wheel_tag(build_data) + return + + # Determine library extension based on platform + system = platform.system() + if system == "Linux": + lib_prefix = "lib" + lib_suffix = ".so" + elif system == "Darwin": + lib_prefix = "lib" + lib_suffix = ".dylib" + elif system == "Windows": + lib_prefix = "" + lib_suffix = ".dll" + else: + msg = f"Unsupported platform: {system}" + raise RuntimeError(msg) + + lib_name = "pecos_selene_stab_mps" + cargo_package = "pecos-selene-stab-mps" + + self.app.display_info(f"Building {cargo_package}...") + + # Run cargo build from the PECOS workspace root + # Plugin is at python/selene-plugins//, so 3 levels up to workspace + workspace_root = root.parent.parent.parent + result = subprocess.run( + [ + "cargo", + "build", + "--release", + "--package", + cargo_package, + ], + check=False, + cwd=workspace_root, + capture_output=True, + text=True, + ) + + if result.returncode != 0: + self.app.display_error(f"Failed to build {cargo_package}:") + self.app.display_error(result.stderr) + msg = f"Cargo build failed for {cargo_package}" + raise RuntimeError(msg) + + # Find the compiled library + lib_filename = f"{lib_prefix}{lib_name}{lib_suffix}" + source_lib = workspace_root / "target" / "release" / lib_filename + + if not source_lib.exists(): + msg = f"Built library not found: {source_lib}" + raise RuntimeError(msg) + + # Copy to the _dist/lib directory in the Python package + dest_dir = root / "python" / "pecos_selene_stab_mps" / "_dist" / "lib" + dest_dir.mkdir(parents=True, exist_ok=True) + dest_lib = dest_dir / lib_filename + + self.app.display_info(f"Copying {source_lib} -> {dest_lib}") + shutil.copy2(source_lib, dest_lib) + + # Collect artifacts + artifacts = [] + dist_dir = root / "python" / "pecos_selene_stab_mps" / "_dist" + for artifact in dist_dir.rglob("*"): + if artifact.is_file(): + rel_path = artifact.relative_to(root) + artifacts.append(str(rel_path.as_posix())) + + self.app.display_info("Found artifacts:") + for a in artifacts: + self.app.display_info(f" {a}") + + build_data["artifacts"] += artifacts + self._set_wheel_tag(build_data) diff --git a/python/selene-plugins/pecos-selene-stab-mps/pyproject.toml b/python/selene-plugins/pecos-selene-stab-mps/pyproject.toml new file mode 100644 index 000000000..40b8b2cf1 --- /dev/null +++ b/python/selene-plugins/pecos-selene-stab-mps/pyproject.toml @@ -0,0 +1,36 @@ +[project] +name = "pecos-selene-stab-mps" +version = "0.8.0.dev8" +requires-python = ">=3.10" +description = "PECOS StabMps simulator plugin for the Selene quantum emulator" +license = "Apache-2.0" +dependencies = [ + "selene-core>=0.2", +] + +[project.optional-dependencies] +test = [ + "pytest>=9.0", + "selene-sim>=0.2", + "guppylang>=0.14", +] + +[project.urls] +homepage = "https://pecos.io" +repository = "https://github.com/PECOS-packages/PECOS" + +[build-system] +requires = ["hatchling", "packaging"] +build-backend = "hatchling.build" + +[tool.hatch.build.targets.wheel] +packages = ["python/pecos_selene_stab_mps"] + +[tool.hatch.build.hooks.custom] +path = "hatch_build.py" + +[tool.uv] +cache-keys = [ + { file = "src/**/*.rs" }, + { file = "Cargo.toml" }, +] diff --git a/python/selene-plugins/pecos-selene-stab-mps/python/pecos_selene_stab_mps/__init__.py b/python/selene-plugins/pecos-selene-stab-mps/python/pecos_selene_stab_mps/__init__.py new file mode 100644 index 000000000..dee1a7d44 --- /dev/null +++ b/python/selene-plugins/pecos-selene-stab-mps/python/pecos_selene_stab_mps/__init__.py @@ -0,0 +1,17 @@ +# Copyright 2026 The PECOS Developers +# +# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +# in compliance with the License. You may obtain a copy of the License at +# +# https://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software distributed under the License +# is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +# or implied. See the License for the specific language governing permissions and limitations under +# the License. + +"""PECOS StabMps Selene plugin.""" + +from pecos_selene_stab_mps.plugin import StabMpsPlugin + +__all__ = ["StabMpsPlugin"] diff --git a/python/selene-plugins/pecos-selene-stab-mps/python/pecos_selene_stab_mps/plugin.py b/python/selene-plugins/pecos-selene-stab-mps/python/pecos_selene_stab_mps/plugin.py new file mode 100644 index 000000000..df5738875 --- /dev/null +++ b/python/selene-plugins/pecos-selene-stab-mps/python/pecos_selene_stab_mps/plugin.py @@ -0,0 +1,83 @@ +# Copyright 2026 The PECOS Developers +# +# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +# in compliance with the License. You may obtain a copy of the License at +# +# https://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software distributed under the License +# is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +# or implied. See the License for the specific language governing permissions and limitations under +# the License. + +"""PECOS StabMps plugin for Selene.""" + +import platform +from dataclasses import dataclass +from pathlib import Path + +from selene_core import Simulator + + +@dataclass +class StabMpsPlugin(Simulator): + """PECOS StabMps (stabilizer+MPS) simulator plugin for Selene. + + This plugin provides a StabMps (stabilizer+MPS) simulator backend for Selene using a + stabilizer tableau + MPS decomposition. Clifford gates are applied efficiently, + while cost is polynomial when non-Clifford count is bounded. + + Cost is polynomial in qubits and Clifford gates, exponential in the number + of RZ gates applied. + + Parameters + ---------- + random_seed : int, optional + Seed for the random number generator. If not provided, the seed + will be determined by Selene's shot management. + """ + + random_seed: int | None = None + + def get_init_args(self) -> list[str]: + """Return the initialization arguments for the Rust plugin. + + Returns: + ------- + list[str] + Empty list as StabMps plugin doesn't require additional arguments. + """ + return [] + + @property + def library_file(self) -> Path: + """Return the path to the compiled Rust library. + + Returns: + ------- + Path + Path to the shared library file. + + Raises: + ------ + FileNotFoundError + If no matching library file is found. + """ + libdir = Path(__file__).parent / "_dist" / "lib" + + # Platform-specific library naming + system = platform.system().lower() + if system == "darwin": + patterns = ["libpecos_selene_stab_mps*.dylib"] + elif system == "windows": + patterns = ["pecos_selene_stab_mps*.dll", "pecos_selene_stab_mps*.pyd"] + else: # Linux and others + patterns = ["libpecos_selene_stab_mps*.so"] + + for pattern in patterns: + matches = list(libdir.glob(pattern)) + if matches: + return matches[0] + + msg = f"Could not find PECOS StabMps library in {libdir}" + raise FileNotFoundError(msg) diff --git a/python/selene-plugins/pecos-selene-stab-mps/src/lib.rs b/python/selene-plugins/pecos-selene-stab-mps/src/lib.rs new file mode 100644 index 000000000..7d2c629cb --- /dev/null +++ b/python/selene-plugins/pecos-selene-stab-mps/src/lib.rs @@ -0,0 +1,209 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file +// except in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the +// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either +// express or implied. See the License for the specific language governing permissions and +// limitations under the License. + +//! PECOS `StabMps` simulator plugin for the Selene quantum emulator. +//! +//! Stabilizer tableau + MPS hybrid simulator. Clifford gates are O(n) on the +//! tableau; non-Clifford rotations decompose in the stabilizer basis and +//! apply to the MPS. Cost is polynomial when non-Clifford count is bounded. + +use anyhow::{Result, anyhow, bail}; +use pecos_core::{Angle64, QubitId}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable}; +use pecos_stab_tn::stab_mps::StabMps; +use selene_core::export_simulator_plugin; +use selene_core::simulator::SimulatorInterface; +use selene_core::simulator::interface::SimulatorInterfaceFactory; +use selene_core::utils::MetricValue; +use std::sync::Arc; + +pub struct StabMpsSimulator { + simulator: StabMps, + n_qubits: u64, +} + +impl StabMpsSimulator { + #[allow(clippy::cast_possible_truncation)] + #[inline] + const fn to_usize(value: u64) -> usize { + value as usize + } +} + +impl SimulatorInterface for StabMpsSimulator { + fn exit(&mut self) -> Result<()> { + Ok(()) + } + + fn shot_start(&mut self, _shot_id: u64, seed: u64) -> Result<()> { + self.simulator = StabMps::builder(Self::to_usize(self.n_qubits)) + .seed(seed) + .for_sparse_t() + .build(); + Ok(()) + } + + fn shot_end(&mut self) -> Result<()> { + Ok(()) + } + + fn rxy(&mut self, qubit: u64, theta: f64, phi: f64) -> Result<()> { + if qubit >= self.n_qubits { + return Err(anyhow!( + "RXY(qubit={qubit}) out of bounds (n_qubits={})", + self.n_qubits + )); + } + let q = QubitId(Self::to_usize(qubit)); + self.simulator + .rz(Angle64::from_radians(-phi), &[q]) + .rx(Angle64::from_radians(theta), &[q]) + .rz(Angle64::from_radians(phi), &[q]); + Ok(()) + } + + fn rz(&mut self, qubit: u64, theta: f64) -> Result<()> { + if qubit >= self.n_qubits { + return Err(anyhow!( + "RZ(qubit={qubit}) out of bounds (n_qubits={})", + self.n_qubits + )); + } + self.simulator.rz( + Angle64::from_radians(theta), + &[QubitId(Self::to_usize(qubit))], + ); + Ok(()) + } + + fn rzz(&mut self, qubit1: u64, qubit2: u64, theta: f64) -> Result<()> { + if qubit1 >= self.n_qubits || qubit2 >= self.n_qubits { + return Err(anyhow!( + "RZZ(qubit1={qubit1}, qubit2={qubit2}) out of bounds (n_qubits={})", + self.n_qubits + )); + } + self.simulator.rzz( + Angle64::from_radians(theta), + &[( + QubitId(Self::to_usize(qubit1)), + QubitId(Self::to_usize(qubit2)), + )], + ); + Ok(()) + } + + fn measure(&mut self, qubit: u64) -> Result { + if qubit >= self.n_qubits { + return Err(anyhow!( + "Measure(qubit={qubit}) out of bounds (n_qubits={})", + self.n_qubits + )); + } + let results = self.simulator.mz(&[QubitId(Self::to_usize(qubit))]); + Ok(results[0].outcome) + } + + fn postselect(&mut self, qubit: u64, target_value: bool) -> Result<()> { + if qubit >= self.n_qubits { + return Err(anyhow!( + "Postselect(qubit={qubit}) out of bounds (n_qubits={})", + self.n_qubits + )); + } + let results = self.simulator.mz(&[QubitId(Self::to_usize(qubit))]); + if results[0].outcome != target_value { + return Err(anyhow!( + "Postselect(qubit={qubit}, target={target_value}) failed: got {}", + results[0].outcome + )); + } + Ok(()) + } + + fn reset(&mut self, qubit: u64) -> Result<()> { + if qubit >= self.n_qubits { + return Err(anyhow!( + "Reset(qubit={qubit}) out of bounds (n_qubits={})", + self.n_qubits + )); + } + self.simulator.reset_qubit(QubitId(Self::to_usize(qubit))); + Ok(()) + } + + fn get_metric(&mut self, nth_metric: u8) -> Result> { + match nth_metric { + 0 => Ok(Some(( + "max_bond_dim".to_string(), + MetricValue::U64(self.simulator.max_bond_dim() as u64), + ))), + 1 => Ok(Some(( + "pragmatic_drift_count".to_string(), + MetricValue::U64(self.simulator.pragmatic_drift_count()), + ))), + _ => Ok(None), + } + } + + fn dump_state(&mut self, _file: &std::path::Path, _qubits: &[u64]) -> Result<()> { + Err(anyhow!("State dumping not supported for StabMps")) + } +} + +#[derive(Default)] +pub struct StabMpsSimulatorFactory; + +impl SimulatorInterfaceFactory for StabMpsSimulatorFactory { + type Interface = StabMpsSimulator; + + fn init( + self: Arc, + n_qubits: u64, + args: &[impl AsRef], + ) -> Result> { + let args: Vec = args.iter().map(|s| s.as_ref().to_string()).collect(); + if args.len() > 1 { + bail!( + "Expected no arguments for StabMps plugin, got {}: {:?}", + args.len() - 1, + args.iter().skip(1).collect::>() + ); + } + if n_qubits == 0 { + bail!("Number of qubits must be greater than 0"); + } + Ok(Box::new(StabMpsSimulator { + simulator: StabMps::builder(StabMpsSimulator::to_usize(n_qubits)) + .seed(0) + .for_sparse_t() + .build(), + n_qubits, + })) + } +} + +export_simulator_plugin!(crate::StabMpsSimulatorFactory); + +#[cfg(test)] +mod tests { + use super::StabMpsSimulatorFactory; + use selene_core::simulator::conformance_testing::run_basic_tests; + use std::sync::Arc; + + #[test] + fn basic_conformance_test() { + let interface = Arc::new(StabMpsSimulatorFactory); + let args: Vec = vec![String::new()]; + run_basic_tests(interface, args); + } +} diff --git a/python/selene-plugins/pecos-selene-clifford-rz/Cargo.toml b/python/selene-plugins/pecos-selene-stab-vec/Cargo.toml similarity index 80% rename from python/selene-plugins/pecos-selene-clifford-rz/Cargo.toml rename to python/selene-plugins/pecos-selene-stab-vec/Cargo.toml index 26d3da1ee..40cb39f97 100644 --- a/python/selene-plugins/pecos-selene-clifford-rz/Cargo.toml +++ b/python/selene-plugins/pecos-selene-stab-vec/Cargo.toml @@ -1,15 +1,15 @@ [package] -name = "pecos-selene-clifford-rz" +name = "pecos-selene-stab-vec" version.workspace = true edition.workspace = true license.workspace = true repository.workspace = true keywords.workspace = true categories.workspace = true -description = "PECOS Clifford+RZ simulator plugin for the Selene quantum emulator" +description = "PECOS StabVec simulator plugin for the Selene quantum emulator" [lib] -name = "pecos_selene_clifford_rz" +name = "pecos_selene_stab_vec" path = "src/lib.rs" crate-type = ["cdylib"] diff --git a/python/selene-plugins/pecos-selene-clifford-rz/README.md b/python/selene-plugins/pecos-selene-stab-vec/README.md similarity index 62% rename from python/selene-plugins/pecos-selene-clifford-rz/README.md rename to python/selene-plugins/pecos-selene-stab-vec/README.md index a9585677a..21e0e6a85 100644 --- a/python/selene-plugins/pecos-selene-clifford-rz/README.md +++ b/python/selene-plugins/pecos-selene-stab-vec/README.md @@ -1,27 +1,27 @@ -# PECOS CliffordRz Selene Plugin +# PECOS StabVec Selene Plugin -A Clifford+RZ simulator plugin for the [Selene](https://github.com/Quantinuum/selene) quantum emulator using the PECOS sum-over-Cliffords implementation. +A StabVec (Clifford+RZ) simulator plugin for the [Selene](https://github.com/Quantinuum/selene) quantum emulator using the PECOS sum-over-Cliffords implementation. ## Overview -This plugin provides a Clifford+RZ simulator backend for Selene. It handles Clifford gates efficiently and supports arbitrary RZ rotations via a sum-over-Cliffords decomposition. +This plugin provides a StabVec (Clifford+RZ) simulator backend for Selene. It handles Clifford gates efficiently and supports arbitrary RZ rotations via a sum-over-Cliffords decomposition. The cost is polynomial in qubits and Clifford gates, but exponential in the number of non-Clifford (RZ) gates applied. This makes it well-suited for circuits with many qubits but few non-Clifford gates. ## Installation ```bash -pip install pecos-selene-clifford-rz +pip install pecos-selene-stab-vec ``` ## Usage ```python from selene_sim.build import build -from pecos_selene_clifford_rz import CliffordRzPlugin +from pecos_selene_stab_vec import StabVecPlugin # Create a plugin instance -simulator = CliffordRzPlugin() +simulator = StabVecPlugin() # Use with Selene runner = build(program) @@ -44,7 +44,7 @@ This package requires Rust to build. The Rust components will be automatically c ```bash # From the PECOS repository root -cd python/selene-plugins/pecos-selene-clifford-rz +cd python/selene-plugins/pecos-selene-stab-vec pip install -e ".[test]" ``` diff --git a/python/selene-plugins/pecos-selene-stab-vec/hatch_build.py b/python/selene-plugins/pecos-selene-stab-vec/hatch_build.py new file mode 100644 index 000000000..b262d5464 --- /dev/null +++ b/python/selene-plugins/pecos-selene-stab-vec/hatch_build.py @@ -0,0 +1,153 @@ +# Copyright 2026 The PECOS Developers +# +# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +# in compliance with the License. You may obtain a copy of the License at +# +# https://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software distributed under the License +# is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +# or implied. See the License for the specific language governing permissions and limitations under +# the License. + +"""Custom hatch build hook to compile and include the Rust shared library.""" + +from __future__ import annotations + +import platform +import shutil +import subprocess +import sys +from pathlib import Path +from typing import Any + +from hatchling.builders.hooks.plugin.interface import BuildHookInterface +from packaging.tags import sys_tags + + +class PecosSeleStabVecBuildHook(BuildHookInterface): + """Build hook that compiles the Rust plugin and copies it to the Python package.""" + + def _set_wheel_tag(self, build_data: dict[str, Any]) -> None: + """Set platform-specific wheel tags. + + This ensures the wheel is marked as platform-specific (not pure Python). + We use py3-none-{platform} since we don't bind to Python ABI directly. + """ + build_data["pure_python"] = False + + # Get the appropriate platform tag + tag = next( + iter(t for t in sys_tags() if "manylinux" not in t.platform and "musllinux" not in t.platform), + ) + target_platform = tag.platform + if sys.platform == "darwin": + from hatchling.builders.macos import process_macos_plat_tag + + target_platform = process_macos_plat_tag(target_platform, compat=False) + build_data["tag"] = f"py3-none-{target_platform}" + + self.app.display_info(f"Wheel tag: {build_data['tag']}") + + def initialize( + self, + version: str, + build_data: dict[str, Any], + ) -> None: + """Build the Rust library and include it as an artifact.""" + # Get the root directory (where pyproject.toml is) + root = Path(self.root) + + # Check if library already exists (e.g., from `make build-selene`) + # If so, skip building and just collect artifacts + dist_dir = root / "python" / "pecos_selene_stab_vec" / "_dist" + lib_dir = dist_dir / "lib" + if lib_dir.exists() and any(lib_dir.iterdir()): + self.app.display_info("Library already built, skipping cargo build...") + # Collect artifacts + artifacts = [] + for artifact in dist_dir.rglob("*"): + if artifact.is_file(): + rel_path = artifact.relative_to(root) + artifacts.append(str(rel_path.as_posix())) + if artifacts: + self.app.display_info("Found existing artifacts:") + for a in artifacts: + self.app.display_info(f" {a}") + build_data["artifacts"] += artifacts + self._set_wheel_tag(build_data) + return + + # Determine library extension based on platform + system = platform.system() + if system == "Linux": + lib_prefix = "lib" + lib_suffix = ".so" + elif system == "Darwin": + lib_prefix = "lib" + lib_suffix = ".dylib" + elif system == "Windows": + lib_prefix = "" + lib_suffix = ".dll" + else: + msg = f"Unsupported platform: {system}" + raise RuntimeError(msg) + + lib_name = "pecos_selene_stab_vec" + cargo_package = "pecos-selene-stab-vec" + + self.app.display_info(f"Building {cargo_package}...") + + # Run cargo build from the PECOS workspace root + # Plugin is at python/selene-plugins//, so 3 levels up to workspace + workspace_root = root.parent.parent.parent + result = subprocess.run( + [ + "cargo", + "build", + "--release", + "--package", + cargo_package, + ], + check=False, + cwd=workspace_root, + capture_output=True, + text=True, + ) + + if result.returncode != 0: + self.app.display_error(f"Failed to build {cargo_package}:") + self.app.display_error(result.stderr) + msg = f"Cargo build failed for {cargo_package}" + raise RuntimeError(msg) + + # Find the compiled library + lib_filename = f"{lib_prefix}{lib_name}{lib_suffix}" + source_lib = workspace_root / "target" / "release" / lib_filename + + if not source_lib.exists(): + msg = f"Built library not found: {source_lib}" + raise RuntimeError(msg) + + # Copy to the _dist/lib directory in the Python package + dest_dir = root / "python" / "pecos_selene_stab_vec" / "_dist" / "lib" + dest_dir.mkdir(parents=True, exist_ok=True) + dest_lib = dest_dir / lib_filename + + self.app.display_info(f"Copying {source_lib} -> {dest_lib}") + shutil.copy2(source_lib, dest_lib) + + # Collect artifacts + artifacts = [] + dist_dir = root / "python" / "pecos_selene_stab_vec" / "_dist" + for artifact in dist_dir.rglob("*"): + if artifact.is_file(): + rel_path = artifact.relative_to(root) + artifacts.append(str(rel_path.as_posix())) + + self.app.display_info("Found artifacts:") + for a in artifacts: + self.app.display_info(f" {a}") + + build_data["artifacts"] += artifacts + self._set_wheel_tag(build_data) diff --git a/python/selene-plugins/pecos-selene-clifford-rz/pyproject.toml b/python/selene-plugins/pecos-selene-stab-vec/pyproject.toml similarity index 76% rename from python/selene-plugins/pecos-selene-clifford-rz/pyproject.toml rename to python/selene-plugins/pecos-selene-stab-vec/pyproject.toml index 612d99e0e..ab99967f4 100644 --- a/python/selene-plugins/pecos-selene-clifford-rz/pyproject.toml +++ b/python/selene-plugins/pecos-selene-stab-vec/pyproject.toml @@ -1,8 +1,8 @@ [project] -name = "pecos-selene-clifford-rz" +name = "pecos-selene-stab-vec" version = "0.8.0.dev8" requires-python = ">=3.10" -description = "PECOS Clifford+RZ simulator plugin for the Selene quantum emulator" +description = "PECOS StabVec simulator plugin for the Selene quantum emulator" readme = "README.md" license = "Apache-2.0" dependencies = [ @@ -11,7 +11,7 @@ dependencies = [ [project.optional-dependencies] test = [ - "pytest>=7", + "pytest>=9.0", "selene-sim>=0.2", "guppylang>=0.14", ] @@ -25,7 +25,7 @@ requires = ["hatchling", "packaging"] build-backend = "hatchling.build" [tool.hatch.build.targets.wheel] -packages = ["python/pecos_selene_clifford_rz"] +packages = ["python/pecos_selene_stab_vec"] [tool.hatch.build.hooks.custom] path = "hatch_build.py" diff --git a/python/selene-plugins/pecos-selene-stab-vec/python/pecos_selene_stab_vec/__init__.py b/python/selene-plugins/pecos-selene-stab-vec/python/pecos_selene_stab_vec/__init__.py new file mode 100644 index 000000000..af68a3153 --- /dev/null +++ b/python/selene-plugins/pecos-selene-stab-vec/python/pecos_selene_stab_vec/__init__.py @@ -0,0 +1,17 @@ +# Copyright 2026 The PECOS Developers +# +# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +# in compliance with the License. You may obtain a copy of the License at +# +# https://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software distributed under the License +# is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +# or implied. See the License for the specific language governing permissions and limitations under +# the License. + +"""PECOS StabVec Selene plugin.""" + +from pecos_selene_stab_vec.plugin import StabVecPlugin + +__all__ = ["StabVecPlugin"] diff --git a/python/selene-plugins/pecos-selene-clifford-rz/python/pecos_selene_clifford_rz/plugin.py b/python/selene-plugins/pecos-selene-stab-vec/python/pecos_selene_stab_vec/plugin.py similarity index 83% rename from python/selene-plugins/pecos-selene-clifford-rz/python/pecos_selene_clifford_rz/plugin.py rename to python/selene-plugins/pecos-selene-stab-vec/python/pecos_selene_stab_vec/plugin.py index cfcbe6707..dd427e99b 100644 --- a/python/selene-plugins/pecos-selene-clifford-rz/python/pecos_selene_clifford_rz/plugin.py +++ b/python/selene-plugins/pecos-selene-stab-vec/python/pecos_selene_stab_vec/plugin.py @@ -10,7 +10,7 @@ # or implied. See the License for the specific language governing permissions and limitations under # the License. -"""PECOS CliffordRz plugin for Selene.""" +"""PECOS StabVec plugin for Selene.""" import platform from dataclasses import dataclass @@ -20,7 +20,7 @@ @dataclass -class CliffordRzPlugin(Simulator): +class StabVecPlugin(Simulator): """PECOS Clifford+RZ simulator plugin for Selene. This plugin provides a Clifford+RZ simulator backend for Selene using a @@ -45,7 +45,7 @@ def get_init_args(self) -> list[str]: Returns: ------- list[str] - Empty list as CliffordRz plugin doesn't require additional arguments. + Empty list as StabVec plugin doesn't require additional arguments. """ return [] @@ -68,16 +68,16 @@ def library_file(self) -> Path: # Platform-specific library naming system = platform.system().lower() if system == "darwin": - patterns = ["libpecos_selene_clifford_rz*.dylib"] + patterns = ["libpecos_selene_stab_vec*.dylib"] elif system == "windows": - patterns = ["pecos_selene_clifford_rz*.dll", "pecos_selene_clifford_rz*.pyd"] + patterns = ["pecos_selene_stab_vec*.dll", "pecos_selene_stab_vec*.pyd"] else: # Linux and others - patterns = ["libpecos_selene_clifford_rz*.so"] + patterns = ["libpecos_selene_stab_vec*.so"] for pattern in patterns: matches = list(libdir.glob(pattern)) if matches: return matches[0] - msg = f"Could not find PECOS CliffordRz library in {libdir}" + msg = f"Could not find PECOS StabVec library in {libdir}" raise FileNotFoundError(msg) diff --git a/python/selene-plugins/pecos-selene-clifford-rz/src/lib.rs b/python/selene-plugins/pecos-selene-stab-vec/src/lib.rs similarity index 86% rename from python/selene-plugins/pecos-selene-clifford-rz/src/lib.rs rename to python/selene-plugins/pecos-selene-stab-vec/src/lib.rs index e2da98cbd..32c94769a 100644 --- a/python/selene-plugins/pecos-selene-clifford-rz/src/lib.rs +++ b/python/selene-plugins/pecos-selene-stab-vec/src/lib.rs @@ -10,7 +10,7 @@ // or implied. See the License for the specific language governing permissions and limitations under // the License. -//! PECOS `CliffordRz` simulator plugin for the Selene quantum emulator. +//! PECOS `StabVec` simulator plugin for the Selene quantum emulator. //! //! This crate provides a Selene-compatible plugin wrapping the PECOS Clifford+RZ simulator. //! It supports Clifford gates efficiently plus arbitrary RZ rotations via a sum-over-Cliffords @@ -18,22 +18,22 @@ use anyhow::{Result, anyhow, bail}; use pecos_core::{Angle64, QubitId}; -use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, CliffordRz}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, StabVec}; use selene_core::export_simulator_plugin; use selene_core::simulator::SimulatorInterface; use selene_core::simulator::interface::SimulatorInterfaceFactory; use selene_core::utils::MetricValue; use std::sync::Arc; -/// The PECOS `CliffordRz` simulator wrapped for Selene compatibility. -pub struct CliffordRzSimulator { +/// The PECOS `StabVec` simulator wrapped for Selene compatibility. +pub struct StabVecSimulator { /// The underlying PECOS Clifford+RZ simulator - simulator: CliffordRz, + simulator: StabVec, /// Number of qubits in the system n_qubits: u64, } -impl CliffordRzSimulator { +impl StabVecSimulator { /// Convert a `u64` to `usize` for use with the simulator. #[allow(clippy::cast_possible_truncation)] #[inline] @@ -42,13 +42,13 @@ impl CliffordRzSimulator { } } -impl SimulatorInterface for CliffordRzSimulator { +impl SimulatorInterface for StabVecSimulator { fn exit(&mut self) -> Result<()> { Ok(()) } fn shot_start(&mut self, _shot_id: u64, seed: u64) -> Result<()> { - self.simulator = CliffordRz::new_with_seed(Self::to_usize(self.n_qubits), seed); + self.simulator = StabVec::new_with_seed(Self::to_usize(self.n_qubits), seed); Ok(()) } @@ -180,17 +180,17 @@ impl SimulatorInterface for CliffordRzSimulator { fn dump_state(&mut self, _file: &std::path::Path, _qubits: &[u64]) -> Result<()> { Err(anyhow!( - "State dumping is not supported for the CliffordRz simulator" + "State dumping is not supported for the StabVec simulator" )) } } -/// Factory for creating `CliffordRzSimulator` instances. +/// Factory for creating `StabVecSimulator` instances. #[derive(Default)] -pub struct CliffordRzSimulatorFactory; +pub struct StabVecSimulatorFactory; -impl SimulatorInterfaceFactory for CliffordRzSimulatorFactory { - type Interface = CliffordRzSimulator; +impl SimulatorInterfaceFactory for StabVecSimulatorFactory { + type Interface = StabVecSimulator; fn init( self: Arc, @@ -201,7 +201,7 @@ impl SimulatorInterfaceFactory for CliffordRzSimulatorFactory { if args.len() > 1 { bail!( - "Expected no arguments for the PECOS CliffordRz plugin, got {} arguments: {:?}", + "Expected no arguments for the PECOS StabVec plugin, got {} arguments: {:?}", args.len() - 1, args.iter().skip(1).collect::>() ); @@ -211,25 +211,25 @@ impl SimulatorInterfaceFactory for CliffordRzSimulatorFactory { bail!("Number of qubits must be greater than 0"); } - Ok(Box::new(CliffordRzSimulator { - simulator: CliffordRz::new_with_seed(CliffordRzSimulator::to_usize(n_qubits), 0), + Ok(Box::new(StabVecSimulator { + simulator: StabVec::new_with_seed(StabVecSimulator::to_usize(n_qubits), 0), n_qubits, })) } } // Export the plugin using Selene's macro -export_simulator_plugin!(crate::CliffordRzSimulatorFactory); +export_simulator_plugin!(crate::StabVecSimulatorFactory); #[cfg(test)] mod tests { - use super::CliffordRzSimulatorFactory; + use super::StabVecSimulatorFactory; use selene_core::simulator::conformance_testing::run_basic_tests; use std::sync::Arc; #[test] fn basic_conformance_test() { - let interface = Arc::new(CliffordRzSimulatorFactory); + let interface = Arc::new(StabVecSimulatorFactory); let args: Vec = vec![String::new()]; run_basic_tests(interface, args); } diff --git a/python/selene-plugins/pecos-selene-clifford-rz/tests/test_clifford_rz.py b/python/selene-plugins/pecos-selene-stab-vec/tests/test_stab_vec.py similarity index 86% rename from python/selene-plugins/pecos-selene-clifford-rz/tests/test_clifford_rz.py rename to python/selene-plugins/pecos-selene-stab-vec/tests/test_stab_vec.py index 9c736031d..140cf10c0 100644 --- a/python/selene-plugins/pecos-selene-clifford-rz/tests/test_clifford_rz.py +++ b/python/selene-plugins/pecos-selene-stab-vec/tests/test_stab_vec.py @@ -10,19 +10,19 @@ # or implied. See the License for the specific language governing permissions and limitations under # the License. -"""Tests for the PECOS CliffordRz Selene plugin.""" +"""Tests for the PECOS StabVec Selene plugin.""" import pytest from guppylang import guppy from guppylang.std.angles import pi from guppylang.std.builtins import result from guppylang.std.quantum import crz, cx, discard, h, measure, qubit, reset, rx, ry, rz -from pecos_selene_clifford_rz import CliffordRzPlugin +from pecos_selene_stab_vec import StabVecPlugin from selene_sim.build import build -class TestCliffordRzBasic: - """Basic functionality tests for the CliffordRz plugin.""" +class TestStabVecBasic: + """Basic functionality tests for the StabVec plugin.""" def test_single_qubit_discard(self) -> None: """Test that a qubit can be created and discarded.""" @@ -33,7 +33,7 @@ def main() -> None: discard(q) runner = build(main.compile()) - simulator = CliffordRzPlugin(random_seed=42) + simulator = StabVecPlugin(random_seed=42) results = list(runner.run(simulator, n_qubits=1)) assert len(results) == 0 @@ -48,7 +48,7 @@ def main() -> None: result("outcome", bit) runner = build(main.compile()) - simulator = CliffordRzPlugin(random_seed=42) + simulator = StabVecPlugin(random_seed=42) results = list(runner.run(simulator, n_qubits=1)) assert dict(results)["outcome"] == 0 @@ -64,13 +64,13 @@ def main() -> None: result("outcome", bit) runner = build(main.compile()) - simulator = CliffordRzPlugin(random_seed=123) + simulator = StabVecPlugin(random_seed=123) results = list(runner.run(simulator, n_qubits=1)) assert dict(results)["outcome"] in [0, 1] -class TestCliffordRzBellState: +class TestStabVecBellState: """Tests involving Bell states and entanglement.""" def test_bell_state_correlation(self) -> None: @@ -88,14 +88,14 @@ def main() -> None: result("q1", b1) runner = build(main.compile()) - simulator = CliffordRzPlugin(random_seed=999) + simulator = StabVecPlugin(random_seed=999) results = list(runner.run(simulator, n_qubits=2)) d = dict(results) assert d["q0"] == d["q1"], f"Bell state correlation failed: {d}" -class TestCliffordRzArbitraryRotations: +class TestStabVecArbitraryRotations: """Tests for arbitrary rotation angles (non-Clifford).""" def test_t_gate_like_rotation(self) -> None: @@ -111,7 +111,7 @@ def main() -> None: result("outcome", bit) runner = build(main.compile()) - simulator = CliffordRzPlugin(random_seed=42) + simulator = StabVecPlugin(random_seed=42) for _ in range(5): results = list(runner.run(simulator, n_qubits=1)) @@ -130,7 +130,7 @@ def main() -> None: result("outcome", bit) runner = build(main.compile()) - simulator = CliffordRzPlugin(random_seed=42) + simulator = StabVecPlugin(random_seed=42) results = list(runner.run(simulator, n_qubits=1)) assert dict(results)["outcome"] in [0, 1] @@ -146,7 +146,7 @@ def main() -> None: result("outcome", bit) runner = build(main.compile()) - simulator = CliffordRzPlugin(random_seed=42) + simulator = StabVecPlugin(random_seed=42) results = list(runner.run(simulator, n_qubits=1)) assert dict(results)["outcome"] in [0, 1] @@ -162,7 +162,7 @@ def main() -> None: result("outcome", bit) runner = build(main.compile()) - simulator = CliffordRzPlugin(random_seed=42) + simulator = StabVecPlugin(random_seed=42) results = list(runner.run(simulator, n_qubits=1)) assert dict(results)["outcome"] in [0, 1] @@ -182,7 +182,7 @@ def main() -> None: result("q1", b1) runner = build(main.compile()) - simulator = CliffordRzPlugin(random_seed=42) + simulator = StabVecPlugin(random_seed=42) results = list(runner.run(simulator, n_qubits=2)) d = dict(results) @@ -190,7 +190,7 @@ def main() -> None: assert d["q1"] in [0, 1] -class TestCliffordRzReset: +class TestStabVecReset: """Tests for qubit reset.""" def test_reset_after_x(self) -> None: @@ -207,7 +207,7 @@ def main() -> None: result("outcome", bit) runner = build(main.compile()) - simulator = CliffordRzPlugin(random_seed=42) + simulator = StabVecPlugin(random_seed=42) results = list(runner.run(simulator, n_qubits=1)) assert dict(results)["outcome"] == 0 @@ -225,29 +225,29 @@ def main() -> None: result("outcome", bit) runner = build(main.compile()) - simulator = CliffordRzPlugin(random_seed=42) + simulator = StabVecPlugin(random_seed=42) results = list(runner.run(simulator, n_qubits=1)) assert dict(results)["outcome"] in [0, 1] -class TestCliffordRzPlugin: +class TestStabVecPlugin: """Tests for the plugin interface.""" def test_library_file_exists(self) -> None: """Test that the library file property returns a valid path.""" - plugin = CliffordRzPlugin() + plugin = StabVecPlugin() lib_path = plugin.library_file assert lib_path.name.startswith( - "libpecos_selene_clifford_rz", + "libpecos_selene_stab_vec", ) or lib_path.name.startswith( - "pecos_selene_clifford_rz", + "pecos_selene_stab_vec", ) def test_init_args_empty(self) -> None: """Test that init args are empty (no special parameters).""" - plugin = CliffordRzPlugin() + plugin = StabVecPlugin() args = plugin.get_init_args() assert len(args) == 0 diff --git a/python/selene-plugins/pecos-selene-stabilizer/README.md b/python/selene-plugins/pecos-selene-stabilizer/README.md index 6a55d40e3..5b8d27714 100644 --- a/python/selene-plugins/pecos-selene-stabilizer/README.md +++ b/python/selene-plugins/pecos-selene-stabilizer/README.md @@ -16,13 +16,13 @@ pip install pecos-selene-stabilizer ```python from selene_sim.build import build -from pecos_selene_stabilizer import StabPlugin +from pecos_selene_stabilizer import StabilizerPlugin # Create a plugin instance -simulator = StabPlugin() +simulator = StabilizerPlugin() # Or customize the angle threshold for Clifford approximation -simulator = StabPlugin(angle_threshold=1e-4) +simulator = StabilizerPlugin(angle_threshold=1e-4) # Use with Selene runner = build(program) diff --git a/python/selene-plugins/pecos-selene-stabilizer/pyproject.toml b/python/selene-plugins/pecos-selene-stabilizer/pyproject.toml index ee2dc8841..ab5fbbf82 100644 --- a/python/selene-plugins/pecos-selene-stabilizer/pyproject.toml +++ b/python/selene-plugins/pecos-selene-stabilizer/pyproject.toml @@ -11,7 +11,7 @@ dependencies = [ [project.optional-dependencies] test = [ - "pytest>=7", + "pytest>=9.0", "selene-sim>=0.2", "guppylang>=0.14", ] diff --git a/python/selene-plugins/pecos-selene-stabilizer/python/pecos_selene_stabilizer/__init__.py b/python/selene-plugins/pecos-selene-stabilizer/python/pecos_selene_stabilizer/__init__.py index 2f90dd96c..db59f0bbf 100644 --- a/python/selene-plugins/pecos-selene-stabilizer/python/pecos_selene_stabilizer/__init__.py +++ b/python/selene-plugins/pecos-selene-stabilizer/python/pecos_selene_stabilizer/__init__.py @@ -10,8 +10,8 @@ # or implied. See the License for the specific language governing permissions and limitations under # the License. -"""PECOS Stab simulator plugin for the Selene quantum emulator.""" +"""PECOS stabilizer simulator plugin for the Selene quantum emulator.""" -from pecos_selene_stabilizer.plugin import StabPlugin +from pecos_selene_stabilizer.plugin import StabilizerPlugin -__all__ = ["StabPlugin"] +__all__ = ["StabilizerPlugin"] diff --git a/python/selene-plugins/pecos-selene-stabilizer/python/pecos_selene_stabilizer/plugin.py b/python/selene-plugins/pecos-selene-stabilizer/python/pecos_selene_stabilizer/plugin.py index 9a8abce53..fd3c8985e 100644 --- a/python/selene-plugins/pecos-selene-stabilizer/python/pecos_selene_stabilizer/plugin.py +++ b/python/selene-plugins/pecos-selene-stabilizer/python/pecos_selene_stabilizer/plugin.py @@ -10,7 +10,7 @@ # or implied. See the License for the specific language governing permissions and limitations under # the License. -"""PECOS Stab simulator plugin for Selene.""" +"""PECOS stabilizer simulator plugin for Selene.""" import platform from dataclasses import dataclass @@ -20,11 +20,11 @@ @dataclass -class StabPlugin(Simulator): - """A plugin for using the PECOS Stab stabilizer simulator as a backend for Selene. +class StabilizerPlugin(Simulator): + """A plugin for using the PECOS stabilizer simulator as a backend for Selene. - PECOS Stab is a stabilizer simulator that can efficiently simulate - Clifford circuits. As a stabilizer simulator, it can only simulate Clifford operations + The PECOS stabilizer simulator can efficiently simulate Clifford circuits. + As a stabilizer simulator, it can only simulate Clifford operations (rotations that are multiples of pi/2). Attributes: diff --git a/python/selene-plugins/pecos-selene-stabilizer/tests/test_stab.py b/python/selene-plugins/pecos-selene-stabilizer/tests/test_stab.py index 8f48b35be..342562fd4 100644 --- a/python/selene-plugins/pecos-selene-stabilizer/tests/test_stab.py +++ b/python/selene-plugins/pecos-selene-stabilizer/tests/test_stab.py @@ -10,18 +10,18 @@ # or implied. See the License for the specific language governing permissions and limitations under # the License. -"""Tests for the PECOS Stab Selene plugin.""" +"""Tests for the PECOS stabilizer Selene plugin.""" import pytest from guppylang import guppy from guppylang.std.builtins import result from guppylang.std.quantum import cx, discard, h, measure, qubit -from pecos_selene_stabilizer import StabPlugin +from pecos_selene_stabilizer import StabilizerPlugin from selene_sim.build import build -class TestStabBasic: - """Basic functionality tests for the Stab plugin.""" +class TestStabilizerBasic: + """Basic functionality tests for the stabilizer plugin.""" def test_single_qubit_discard(self) -> None: """Test that a qubit can be created and discarded.""" @@ -32,7 +32,7 @@ def main() -> None: discard(q) runner = build(main.compile()) - simulator = StabPlugin(random_seed=42) + simulator = StabilizerPlugin(random_seed=42) # Run a single shot results = list(runner.run(simulator, n_qubits=1)) @@ -48,7 +48,7 @@ def main() -> None: result("outcome", bit) runner = build(main.compile()) - simulator = StabPlugin(random_seed=42) + simulator = StabilizerPlugin(random_seed=42) # Run a single shot results = list(runner.run(simulator, n_qubits=1)) @@ -65,7 +65,7 @@ def main() -> None: result("outcome", bit) runner = build(main.compile()) - simulator = StabPlugin(random_seed=123) + simulator = StabilizerPlugin(random_seed=123) # Run a single shot results = list(runner.run(simulator, n_qubits=1)) @@ -73,7 +73,7 @@ def main() -> None: assert dict(results)["outcome"] in [0, 1] -class TestStabBellState: +class TestStabilizerBellState: """Tests involving Bell states and entanglement.""" def test_bell_state_correlation(self) -> None: @@ -91,7 +91,7 @@ def main() -> None: result("q1", b1) runner = build(main.compile()) - simulator = StabPlugin(random_seed=999) + simulator = StabilizerPlugin(random_seed=999) # Run a single shot results = list(runner.run(simulator, n_qubits=2)) @@ -100,32 +100,32 @@ def main() -> None: assert d["q0"] == d["q1"], f"Bell state correlation failed: {d}" -class TestStabAngleValidation: +class TestStabilizerAngleValidation: """Tests for angle threshold and Clifford validation.""" def test_invalid_angle_threshold(self) -> None: """Test that angle_threshold must be positive.""" with pytest.raises(ValueError, match="greater than zero"): - StabPlugin(angle_threshold=0) + StabilizerPlugin(angle_threshold=0) with pytest.raises(ValueError, match="greater than zero"): - StabPlugin(angle_threshold=-0.1) + StabilizerPlugin(angle_threshold=-0.1) def test_valid_angle_threshold(self) -> None: """Test that valid angle thresholds are accepted.""" - plugin = StabPlugin(angle_threshold=1e-6) + plugin = StabilizerPlugin(angle_threshold=1e-6) assert plugin.angle_threshold == 1e-6 - plugin = StabPlugin(angle_threshold=0.1) + plugin = StabilizerPlugin(angle_threshold=0.1) assert plugin.angle_threshold == 0.1 -class TestStabPlugin: +class TestStabilizerPlugin: """Tests for the plugin interface.""" def test_library_file_exists(self) -> None: """Test that the library file property returns a valid path.""" - plugin = StabPlugin() + plugin = StabilizerPlugin() lib_path = plugin.library_file # The path should be a Path object pointing to the expected location @@ -137,7 +137,7 @@ def test_library_file_exists(self) -> None: def test_init_args(self) -> None: """Test that init args are correctly formatted.""" - plugin = StabPlugin(angle_threshold=1e-5) + plugin = StabilizerPlugin(angle_threshold=1e-5) args = plugin.get_init_args() assert len(args) == 1 @@ -145,7 +145,7 @@ def test_init_args(self) -> None: def test_default_init_args(self) -> None: """Test default init args.""" - plugin = StabPlugin() + plugin = StabilizerPlugin() args = plugin.get_init_args() assert len(args) == 1 diff --git a/python/selene-plugins/pecos-selene-statevec/pyproject.toml b/python/selene-plugins/pecos-selene-statevec/pyproject.toml index 051fb1a87..8cb75aec0 100644 --- a/python/selene-plugins/pecos-selene-statevec/pyproject.toml +++ b/python/selene-plugins/pecos-selene-statevec/pyproject.toml @@ -11,7 +11,7 @@ dependencies = [ [project.optional-dependencies] test = [ - "pytest>=7", + "pytest>=9.0", "selene-sim>=0.2", "guppylang>=0.14", ] diff --git a/ruff.toml b/ruff.toml index d41d74e86..8855358c6 100644 --- a/ruff.toml +++ b/ruff.toml @@ -348,6 +348,7 @@ ignore = [ "python/quantum-pecos/src/pecos/simulators/mps_pytket/state.py" = ["SLF001"] # MPS internal APIs "python/quantum-pecos/tests/guppy/test_helpers.py" = ["SLF001"] # Test metadata marking "python/quantum-pecos/tests/guppy/test_selene_library_integration.py" = ["SLF001"] # Testing internal builder methods +"python/quantum-pecos/tests/pecos/unit/test_surface_sweep_math.py" = ["SLF001"] # Testing internal fit helpers in sweep example script # Try-except patterns (TRY300) - Complex error handling in integration code "python/pecos-rslib/src/pecos_rslib/sim_wrapper.py" = ["TRY300"] # Wrapper patterns diff --git a/scripts/bench_raw_meas_sampling.py b/scripts/bench_raw_meas_sampling.py new file mode 100644 index 000000000..8a89e95af --- /dev/null +++ b/scripts/bench_raw_meas_sampling.py @@ -0,0 +1,127 @@ +#!/usr/bin/env python3 +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 +"""Benchmark: raw measurement sampling / detector DEM vs stabilizer simulation. + +Compares detector DEM (generate_samples), raw meas_sampling, and stabilizer. +Quick smoke test by default (~10s). Use --full for stable headline numbers. + +Usage: + uv run python scripts/bench_raw_meas_sampling.py # quick + .venv/bin/python scripts/bench_raw_meas_sampling.py --full # full (release) +""" + +import sys +import time + +from pecos.qec.surface import SurfacePatch +from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model +from pecos_rslib.qec import DemSampler +from pecos_rslib_exp import meas_sampling, depolarizing, sim_neo, stabilizer + +FULL = "--full" in sys.argv + + +def build(d): + patch = SurfacePatch.create(distance=d) + return _build_surface_tick_circuit_for_native_model(patch, 6, "Z", circuit_source="abstract") + + +def main(): + noise_args = dict(p1=0.005, p2=0.005, p_meas=0.005, p_prep=0.005) + depol = depolarizing().p1(0.005).p2(0.005).p_meas(0.005).p_prep(0.005) + mode = "full" if FULL else "quick" + + print(f"Raw measurement / detector DEM benchmark ({mode}): surface code, 6 rounds, p=0.005") + print("=" * 78) + + # ---- Section 1: Generation only ---- + gen_configs = ( + [(3, [100_000, 1_000_000]), (5, [100_000, 1_000_000]), (7, [100_000, 1_000_000])] + if FULL + else [(3, [10_000, 100_000]), (5, [10_000, 100_000])] + ) + stab_limit = 100_000 if FULL else 10_000 + + print() + print("1. Generation only (no decoding):") + print(f"{'d':>3} {'shots':>10} | {'Det DEM':>9} | {'Raw meas':>9} | {'Stab sim':>9} | {'stab/det':>9}") + print("-" * 72) + + for d, shot_list in gen_configs: + tc = build(d) + sampler = DemSampler.from_circuit(tc, **noise_args) + + for shots in shot_list: + t0 = time.perf_counter() + _ = sampler.generate_samples(shots, seed=42) + t_det = time.perf_counter() - t0 + + t0 = time.perf_counter() + _ = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(shots).seed(42).run() + t_raw = time.perf_counter() - t0 + + if shots <= stab_limit: + t0 = time.perf_counter() + _ = sim_neo(tc).quantum(stabilizer()).noise(depol).shots(shots).seed(42).run() + t_stab = time.perf_counter() - t0 + stab_s = f"{t_stab * 1000:>8.0f}ms" + ratio_s = f"{t_stab / t_det:>8.0f}x" + else: + stab_s = ratio_s = f"{'--':>9}" + + label = f"d={d}" if shots == shot_list[0] else "" + print( + f"{label:>3} {shots:>10,} | {t_det * 1000:>8.1f}ms | " + f"{t_raw * 1000:>8.1f}ms | {stab_s} | {ratio_s}" + ) + print() + + # ---- Section 2: Generate + decode end-to-end ---- + dec_configs = ( + [(3, [10_000, 100_000]), (5, [10_000, 100_000])] + if FULL + else [(3, [1_000, 10_000]), (5, [1_000])] + ) + + print("2. Detector DEM generate + pymatching decode:") + print(f"{'d':>3} {'shots':>10} | {'generate':>9} | {'decode':>9} | {'total':>9} | {'gen%':>6}") + print("-" * 62) + + import stim + from pecos.qec.surface.circuit_builder import tick_circuit_to_stim + + for d, shot_list in dec_configs: + tc = build(d) + sampler = DemSampler.from_circuit(tc, **noise_args) + stim_str = tick_circuit_to_stim(tc, **noise_args) + dem_str = str(stim.Circuit(stim_str).detector_error_model(decompose_errors=True)) + + for shots in shot_list: + t0 = time.perf_counter() + batch = sampler.generate_samples(shots, seed=42) + t_gen = time.perf_counter() - t0 + + t0 = time.perf_counter() + _ = batch.decode_count(dem_str, "pymatching") + t_dec = time.perf_counter() - t0 + + t_total = t_gen + t_dec + gen_pct = t_gen / t_total * 100 + + label = f"d={d}" if shots == shot_list[0] else "" + print( + f"{label:>3} {shots:>10,} | {t_gen * 1000:>8.1f}ms | " + f"{t_dec * 1000:>8.1f}ms | {t_total * 1000:>8.1f}ms | {gen_pct:>5.1f}%" + ) + print() + + print("Notes:") + print(" generate_samples is 3-6x faster after columnar SampleBatch.") + print(" End-to-end generate+decode is decode-dominated (<1% generation).") + if not FULL: + print(" Use --full for larger shot counts and stable headline numbers.") + + +if __name__ == "__main__": + main() diff --git a/scripts/compare_meas_sampling_pipeline.py b/scripts/compare_meas_sampling_pipeline.py new file mode 100644 index 000000000..fb64b916d --- /dev/null +++ b/scripts/compare_meas_sampling_pipeline.py @@ -0,0 +1,211 @@ +#!/usr/bin/env python3 +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 +"""Compare meas_sampling pipeline against native DEM sampler on surface-code memory. + +Uses the Guppy → traced QIS → TickCircuit pipeline (lowered to Clifford gates). +Decodes with PyMatching. Compares logical error rates and timing. + +Usage: + .venv/bin/python scripts/compare_meas_sampling_pipeline.py + .venv/bin/python scripts/compare_meas_sampling_pipeline.py --distances 3 5 7 --shots 10000 +""" + +from __future__ import annotations + +import argparse +import json +import time + +import numpy as np +import pymatching +import stim + +from pecos.qec.surface import SurfacePatch +from pecos.qec.surface.circuit_builder import tick_circuit_to_stim +from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model +from pecos_rslib.qec import DemSampler +from pecos_rslib_exp import depolarizing, meas_sampling, sim_neo + + +def build_circuit(distance, rounds, basis="Z"): + """Build a traced-QIS surface-code TickCircuit, lowered to Clifford gates.""" + patch = SurfacePatch.create(distance=distance) + tc = _build_surface_tick_circuit_for_native_model( + patch, rounds, basis, circuit_source="traced_qis" + ) + # Lower R1XY/RZ rotations to standard Clifford gates (H, SZ, SZdg, etc.) + tc.lower_clifford_rotations() + return tc + + +def get_pymatching_decoder(tc, noise_args): + """Build a PyMatching decoder from a circuit's Stim DEM.""" + stim_str = tick_circuit_to_stim(tc, **noise_args) + dem = stim.Circuit(stim_str).detector_error_model(decompose_errors=True) + return pymatching.Matching.from_detector_error_model(dem) + + +def run_meas_sampling(tc, noise_args, shots, seed): + """Sample raw measurements via meas_sampling.""" + depol = depolarizing().p1(noise_args["p1"]).p2(noise_args["p2"]).p_meas( + noise_args["p_meas"] + ).p_prep(noise_args["p_prep"]) + + t0 = time.perf_counter() + result = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(shots).seed(seed).run() + t_sample = time.perf_counter() - t0 + return result, t_sample + + +def extract_and_decode(result, tc, matching, shots): + """Extract detection events from raw measurements and decode with PyMatching.""" + det_json = json.loads(tc.get_meta("detectors")) + obs_json_str = tc.get_meta("observables") + obs_json = json.loads(obs_json_str) if obs_json_str else [] + num_meas = int(tc.get_meta("num_measurements")) + num_dets = len(det_json) + + t0 = time.perf_counter() + + errors = 0 + syndrome = np.zeros(num_dets, dtype=np.uint8) + + for shot_idx in range(shots): + row = result[shot_idx] + + # Extract detector events + syndrome.fill(0) + for i, det in enumerate(det_json): + val = 0 + for rec in det["records"]: + idx = num_meas + rec + if 0 <= idx < len(row): + val ^= row[idx] + syndrome[i] = val + + # Extract observable flips + actual_mask = 0 + for i, obs in enumerate(obs_json): + val = 0 + for rec in obs["records"]: + idx = num_meas + rec + if 0 <= idx < len(row): + val ^= row[idx] + if val: + actual_mask |= 1 << i + + # Decode + predicted = matching.decode(syndrome) + pred_mask = sum(int(v) << j for j, v in enumerate(predicted)) + if pred_mask != actual_mask: + errors += 1 + + t_decode = time.perf_counter() - t0 + return errors, t_decode + + +def run_native_sampler(tc, noise_args, matching, shots, seed): + """Sample + decode via the native DEM sampler path.""" + sampler = DemSampler.from_circuit(tc, **noise_args) + num_dets = sampler.num_detectors + + t0 = time.perf_counter() + batch = sampler.generate_samples(shots, seed=seed) + t_sample = time.perf_counter() - t0 + + t0 = time.perf_counter() + errors = 0 + syndrome = np.zeros(num_dets, dtype=np.uint8) + + for i in range(shots): + syn = batch.get_syndrome(i) + for j in range(num_dets): + syndrome[j] = syn[j] + + predicted = matching.decode(syndrome) + pred_mask = sum(int(v) << j for j, v in enumerate(predicted)) + if pred_mask != batch.get_observable_mask(i): + errors += 1 + + t_decode = time.perf_counter() - t0 + return errors, t_sample, t_decode + + +def main(): + parser = argparse.ArgumentParser(description=__doc__) + parser.add_argument("--distances", type=int, nargs="+", default=[3, 5]) + parser.add_argument( + "--rounds-per-d", + type=int, + default=3, + help="Syndrome rounds = distance * rounds_per_d", + ) + parser.add_argument("--shots", type=int, default=5000) + parser.add_argument("--error-rate", type=float, default=0.003) + parser.add_argument("--seed", type=int, default=42) + args = parser.parse_args() + + p = args.error_rate + noise_args = {"p1": p * 0.1, "p2": p, "p_meas": p * 0.5, "p_prep": p * 0.5} + + print("=" * 80) + print("meas_sampling vs native DEM sampler: traced-QIS surface-code memory + PyMatching") + print("=" * 80) + print(f" shots={args.shots}, p={p}") + print( + f" noise: p1={noise_args['p1']:.1e} p2={noise_args['p2']:.1e} " + f"p_meas={noise_args['p_meas']:.1e} p_prep={noise_args['p_prep']:.1e}" + ) + print(" circuit: Guppy -> traced QIS -> lower_clifford_rotations()") + print() + + header = ( + f"{'d':>3} {'rounds':>6} | {'backend':>15} | {'sample':>8} | " + f"{'decode':>8} | {'total':>8} | {'LER':>8} | {'errors':>10}" + ) + print(header) + print("-" * len(header)) + + for d in args.distances: + rounds = d * args.rounds_per_d + tc = build_circuit(d, rounds) + + matching = get_pymatching_decoder(tc, noise_args) + + # --- meas_sampling --- + result, t_sample_ms = run_meas_sampling(tc, noise_args, args.shots, args.seed) + errors_ms, t_decode_ms = extract_and_decode(result, tc, matching, args.shots) + ler_ms = errors_ms / args.shots + t_total_ms = t_sample_ms + t_decode_ms + + print( + f"d={d:>1} {rounds:>6} | {'meas_sampling':>15} | {t_sample_ms*1000:>7.0f}ms | " + f"{t_decode_ms*1000:>7.0f}ms | {t_total_ms*1000:>7.0f}ms | " + f"{ler_ms:>7.4f} | {errors_ms:>5}/{args.shots}" + ) + + # --- native DEM sampler --- + errors_ns, t_sample_ns, t_decode_ns = run_native_sampler( + tc, noise_args, matching, args.shots, args.seed + ) + ler_ns = errors_ns / args.shots + t_total_ns = t_sample_ns + t_decode_ns + + print( + f" {' ':>6} | {'native_sampler':>15} | {t_sample_ns*1000:>7.0f}ms | " + f"{t_decode_ns*1000:>7.0f}ms | {t_total_ns*1000:>7.0f}ms | " + f"{ler_ns:>7.4f} | {errors_ns:>5}/{args.shots}" + ) + print() + + print("Notes:") + print(" Circuit: Guppy surface code -> traced QIS -> lower_clifford_rotations()") + print(" Decoder: PyMatching (stim DEM, decompose_errors=True)") + print(" meas_sampling: geometric raw measurement DEM sampler + Python extraction") + print(" native_sampler: DemSampler.generate_samples (detector events directly)") + print(" LER differences from different RNG streams, not systematic bias.") + + +if __name__ == "__main__": + main() diff --git a/scripts/docs/generate_doc_tests.py b/scripts/docs/generate_doc_tests.py index 80c6d917b..d3d46ab4e 100755 --- a/scripts/docs/generate_doc_tests.py +++ b/scripts/docs/generate_doc_tests.py @@ -1252,6 +1252,13 @@ def main() -> None: if not pytest_blocks: continue + # Skip file entirely if every block has an unconditional skip marker + # (e.g. document-level ). No point generating a test file + # full of skipped tests — it just adds noise to pytest output. + if all(b.skip for b in pytest_blocks): + total_skipped += len(pytest_blocks) + continue + # Count skipped blocks total_skipped += sum( 1 diff --git a/scripts/native_bench/bench_pecos/Cargo.lock b/scripts/native_bench/bench_pecos/Cargo.lock index 43b1be4f5..02bd8a052 100644 --- a/scripts/native_bench/bench_pecos/Cargo.lock +++ b/scripts/native_bench/bench_pecos/Cargo.lock @@ -2004,7 +2004,7 @@ dependencies = [ "num-complex", "num-traits", "pecos-random", - "rand 0.10.0", + "rand 0.10.1", "rand_core 0.10.0", "smallvec", "thiserror 2.0.18", @@ -2049,7 +2049,7 @@ dependencies = [ "pecos-random", "pecos-simulators", "pollster", - "rand 0.10.0", + "rand 0.10.1", "rand_core 0.10.0", "serde_json", "wgpu", @@ -2066,7 +2066,7 @@ dependencies = [ "num-complex", "num-traits", "pecos-random", - "rand 0.10.0", + "rand 0.10.1", "rustworkx-core", "serde", "serde_json", @@ -2088,7 +2088,7 @@ dependencies = [ name = "pecos-random" version = "0.2.0-dev.0" dependencies = [ - "rand 0.10.0", + "rand 0.10.1", "rand_core 0.10.0", "rapidhash", "wide 1.2.0", @@ -2102,7 +2102,7 @@ dependencies = [ "pecos-core", "pecos-quantum", "pecos-random", - "rand 0.10.0", + "rand 0.10.1", "rayon", "smallvec", "wide 1.2.0", @@ -2261,7 +2261,7 @@ dependencies = [ "bytes", "getrandom 0.3.4", "lru-slab", - "rand 0.9.2", + "rand 0.9.3", "ring", "rustc-hash 2.1.2", "rustls", @@ -2316,9 +2316,9 @@ checksum = "dc33ff2d4973d518d823d61aa239014831e521c75da58e3df4840d3f47749d09" [[package]] name = "rand" -version = "0.9.2" +version = "0.9.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "6db2770f06117d490610c7488547d543617b21bfa07796d7a12f6f1bd53850d1" +checksum = "7ec095654a25171c2124e9e3393a930bddbffdc939556c914957a4c3e0a87166" dependencies = [ "rand_chacha", "rand_core 0.9.5", @@ -2326,9 +2326,9 @@ dependencies = [ [[package]] name = "rand" -version = "0.10.0" +version = "0.10.1" 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upload-time = "2026-04-15T03:56:11.85Z" }, ] From 120cc0df9ae277f88bfa79036befd275ecdbea16 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Fri, 8 May 2026 11:13:05 -0600 Subject: [PATCH 051/125] Add debug findings for InfluenceBuilder regression --- crates/pecos-qec/tests/fault_enumeration_example.rs | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/crates/pecos-qec/tests/fault_enumeration_example.rs b/crates/pecos-qec/tests/fault_enumeration_example.rs index c9164f4ad..b25d2b751 100644 --- a/crates/pecos-qec/tests/fault_enumeration_example.rs +++ b/crates/pecos-qec/tests/fault_enumeration_example.rs @@ -289,13 +289,14 @@ fn repetition_code_labels() { .with_circuit_annotations(&dag) .build(); - // Check DEM-output labels are populated + // Check DEM-output labels are populated (observables + tracked ops) println!("DEM output labels: {:?}", map.dem_output_labels); + // 1 observable (logical_Z) + 1 tracked operator (logical_X) = 2 labels assert_eq!(map.dem_output_labels.len(), 2); - assert_eq!(map.dem_output_labels[0].as_deref(), Some("logical_Z")); - assert_eq!(map.dem_output_labels[1].as_deref(), Some("logical_X")); + assert_eq!(map.num_dem_outputs(), 1, "1 observable"); + assert_eq!(map.num_tracked_ops(), 1, "1 tracked operator"); - // Labels accessible via index + // Labels accessible via internal index assert_eq!(map.dem_output_label(0), Some("logical_Z")); assert_eq!(map.dem_output_label(1), Some("logical_X")); assert_eq!(map.dem_output_label(99), None); From 7f1ded15c988ab560b23949b03c8d956e9a47ee2 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Fri, 8 May 2026 11:17:32 -0600 Subject: [PATCH 052/125] Fix InfluenceBuilder to populate observables from circuit annotations --- .../src/fault_tolerance/influence_builder.rs | 55 +++++++++++++++---- 1 file changed, 44 insertions(+), 11 deletions(-) diff --git a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs index 7748f5b1e..d0a381ac1 100644 --- a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs @@ -122,12 +122,14 @@ impl<'a> InfluenceBuilder<'a> { self } - /// Extract tracked operator annotations from the circuit. + /// Extract observable and tracked-operator annotations from the circuit. + /// + /// Observable annotations define logical observables via measurement records. + /// For backward propagation, each observable is converted to a Z-type Pauli + /// on the measured qubits, starting from the latest measurement node. /// /// Operator annotations have a corresponding `PauliOperatorMeta` node - /// that marks their time position. Observable annotations are - /// measurement-record outputs and are handled by DEM/sampler builders, - /// not by backward tracked-operator propagation. + /// that marks their time position. /// /// Detector annotations are NOT handled here -- they are processed /// by `DemSamplerBuilder::with_circuit_annotations` which maps them @@ -145,6 +147,28 @@ impl<'a> InfluenceBuilder<'a> { let mut operator_idx = 0; for ann in circuit.annotations() { match &ann.kind { + pecos_quantum::AnnotationKind::Observable { measurement_nodes } => { + // Convert measurement-based observable to Z-Pauli on measured qubits. + // Backward propagation starts from the latest measurement node. + let mut qubits = Vec::new(); + let mut latest_node = None; + for &meas_node in measurement_nodes { + if let Some(gate) = circuit.gate(meas_node) { + for q in &gate.qubits { + qubits.push(q.index()); + } + } + latest_node = Some( + latest_node.map_or(meas_node, |prev: usize| prev.max(meas_node)), + ); + } + let pauli = PauliString::zs(&qubits); + self.pauli_operators.push(( + DemOutputMetadata::observable(pauli) + .with_optional_label(ann.label.clone()), + latest_node, + )); + } pecos_quantum::AnnotationKind::Operator => { let meta_node = meta_nodes.get(operator_idx).copied(); operator_idx += 1; @@ -154,7 +178,6 @@ impl<'a> InfluenceBuilder<'a> { meta_node, )); } - pecos_quantum::AnnotationKind::Observable { .. } => {} pecos_quantum::AnnotationKind::Detector { .. } => { // Detectors handled separately by DemSamplerBuilder } @@ -996,7 +1019,7 @@ mod tests { } #[test] - fn test_circuit_annotation_dem_output_metadata_tracks_only_operator_annotations() { + fn test_circuit_annotation_dem_output_metadata_tracks_observables_and_operators() { use pecos_core::pauli::constructors::X; let mut dag = DagCircuit::new(); @@ -1010,14 +1033,24 @@ mod tests { .with_circuit_annotations(&dag) .build(); - assert_eq!(map.num_dem_outputs(), 0); - assert_eq!(map.num_tracked_ops(), 1); - assert_eq!(map.dem_output_metadata.len(), 1); + // 1 observable (record_obs) + 1 tracked operator (track_x) = 2 DEM outputs + assert_eq!(map.num_dem_outputs(), 1, "1 observable"); + assert_eq!(map.num_tracked_ops(), 1, "1 tracked operator"); + assert_eq!(map.dem_output_metadata.len(), 2); + + // Observable comes first (annotations are processed in order) assert_eq!( map.dem_output_metadata[0].kind, + DemOutputKind::Observable + ); + assert_eq!(map.dem_output_metadata[0].label.as_deref(), Some("record_obs")); + + // Tracked operator second + assert_eq!( + map.dem_output_metadata[1].kind, DemOutputKind::TrackedOperator ); - assert_eq!(map.dem_output_metadata[0].label.as_deref(), Some("track_x")); - assert_eq!(map.dem_output_metadata[0].pauli.to_sparse_str(), "+X0"); + assert_eq!(map.dem_output_metadata[1].label.as_deref(), Some("track_x")); + assert_eq!(map.dem_output_metadata[1].pauli.to_sparse_str(), "+X0"); } } From fbbef6c4e4110f71c1f8f8463b3897eaceed7f59 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Fri, 8 May 2026 13:44:46 -0600 Subject: [PATCH 053/125] Fix duplicate observable handling, split-time propagation, compact decoder IDs --- .../src/fault_tolerance/correlation.rs | 2 +- .../src/fault_tolerance/dem_builder.rs | 9 +- .../fault_tolerance/dem_builder/builder.rs | 46 ++- .../dem_builder/dem_sampler.rs | 72 ++-- .../dem_builder/equivalence.rs | 17 +- .../fault_tolerance/dem_builder/sampler.rs | 116 ++++-- .../src/fault_tolerance/dem_builder/types.rs | 321 ++++++++++----- .../src/fault_tolerance/fault_sampler.rs | 14 +- .../src/fault_tolerance/influence_builder.rs | 389 +++++++++++++----- .../src/fault_tolerance/lookup_decoder.rs | 128 ++++-- .../src/fault_tolerance/propagator.rs | 18 +- .../src/fault_tolerance/propagator/dag.rs | 109 +++-- .../targeted_lookup_decoder.rs | 44 +- .../src/fault_tolerance_bindings.rs | 31 +- 14 files changed, 913 insertions(+), 403 deletions(-) diff --git a/crates/pecos-qec/src/fault_tolerance/correlation.rs b/crates/pecos-qec/src/fault_tolerance/correlation.rs index 7ab4270ab..40267737b 100644 --- a/crates/pecos-qec/src/fault_tolerance/correlation.rs +++ b/crates/pecos-qec/src/fault_tolerance/correlation.rs @@ -391,7 +391,7 @@ pub fn fit_dem_to_marginals( (fitted, residuals) } -/// Format fitted mechanisms as a Stim DEM string. +/// Format fitted mechanisms as a standard DEM string. pub fn mechanisms_to_dem_string(mechanisms: &[DemMechanism]) -> String { let mut lines = Vec::new(); for mech in mechanisms { diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder.rs index 43e640073..47de8b37e 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder.rs @@ -12,9 +12,8 @@ //! Detector Error Model (DEM) generation from fault influence maps. //! -//! This module provides Rust-native DEM generation that produces output -//! compatible with Stim's format. It uses the per-qubit fault model for -//! accurate depolarizing noise analysis. +//! This module provides Rust-native DEM generation in standard DEM text format. +//! It uses the per-qubit fault model for accurate depolarizing noise analysis. //! //! # Architecture //! @@ -39,7 +38,7 @@ //! .with_observables_json("[]")? //! .build(); //! -//! // Output in Stim format (non-decomposed). +//! // Output in standard DEM format (non-decomposed). //! let _ = dem.to_string(); //! # Ok(()) //! # } @@ -47,7 +46,7 @@ //! //! # Error Decomposition //! -//! When using `to_stim_format_decomposed()`, hyperedge errors (affecting 3+ +//! When using decomposed DEM output, hyperedge errors (affecting 3+ //! detectors) are decomposed into combinations of graphlike errors (affecting //! 1-2 detectors). This is necessary for MWPM decoders which only work on //! graphs, not hypergraphs. diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs index 62a167057..254fc01b3 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs @@ -256,7 +256,8 @@ impl<'a> DemBuilder<'a> { let num_influence_dem_outputs = self .num_influence_dem_outputs() .max(self.influence_map.dem_output_metadata.len()); - let mut dem = DetectorErrorModel::with_capacity(self.detectors.len(), self.observables.len()); + let mut dem = + DetectorErrorModel::with_capacity(self.detectors.len(), self.observables.len()); // Add detector definitions for det in &self.detectors { @@ -296,7 +297,7 @@ impl<'a> DemBuilder<'a> { } } - // Add observable definitions in the standard Stim `L` namespace. + // Add observable definitions in the standard `L` namespace. // Observable IDs are not shifted by tracked operators. for obs in &self.observables { let def = DemOutput::new(obs.id).with_records(obs.records.iter().copied()); @@ -816,6 +817,7 @@ impl<'a> DemBuilder<'a> { fn build_measurement_mappings(&self) -> (BTreeMap>, BTreeMap>) { let mut meas_to_detectors: BTreeMap> = BTreeMap::new(); let mut meas_to_observables: BTreeMap> = BTreeMap::new(); + let influence_observable_ids = self.influence_map.observable_ids(); // Build a mapping from (qubit, occurrence_index) to influence_map_index // This handles multi-round circuits where the same qubit is measured multiple times @@ -879,6 +881,9 @@ impl<'a> DemBuilder<'a> { } for obs in &self.observables { + if influence_observable_ids.contains(&obs.id) { + continue; + } for &rec in &obs.records { if let Some(tc_meas_idx) = record_offset_to_absolute_index(self.num_measurements, rec) @@ -1232,8 +1237,7 @@ fn build_dem_from_circuit( use pecos_num::graph::Attribute; let mut influence_map = DagFaultAnalyzer::new(circuit).build_influence_map(); - let annotated_observable_records = - observable_records_from_annotations(circuit, &influence_map); + let annotated_observable_records = observable_records_from_annotations(circuit, &influence_map); let annotation_map = InfluenceBuilder::new(circuit) .with_circuit_annotations(circuit) .build(); @@ -1419,6 +1423,40 @@ mod tests { ); } + #[test] + fn test_circuit_observable_annotation_is_not_double_counted() { + use pecos_quantum::DagCircuit; + + let mut circuit = DagCircuit::new(); + circuit.pz(&[0]); + let meas = circuit.mz(&[0]); + circuit.observable_labeled("obs0", &[meas[0]]); + + let dem = DemBuilder::from_circuit(&circuit, 0.0, 0.0, 1.0, 0.0); + + assert_eq!(dem.num_dem_outputs(), 1); + assert_eq!(dem.num_observables(), 1); + assert_eq!(dem.dem_outputs().len(), 1); + assert_eq!(dem.dem_outputs()[0].id, 0); + assert_eq!(dem.dem_outputs()[0].records.as_slice(), &[-1]); + assert_eq!(dem.dem_outputs()[0].label.as_deref(), Some("obs0")); + + let logical_observable_lines = dem + .to_string() + .lines() + .filter(|line| *line == "logical_observable L0") + .count(); + assert_eq!(logical_observable_lines, 1); + + let summaries = dem.contribution_effect_summaries(); + assert!( + summaries + .iter() + .any(|summary| summary.effect.dem_outputs.as_slice() == [0]), + "measurement fault should flip observable L0 once, not cancel" + ); + } + #[test] fn test_from_tick_circuit_tracks_face_gate_fault_sources() { use pecos_core::QubitId; diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index d79c58fb6..f74910049 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -20,7 +20,8 @@ //! Fast DEM-style sampler for threshold estimation. //! //! This module provides a sampler that aggregates fault effects directly into -//! detector/`L` target signatures, matching Stim's DEM sampler semantics. +//! detector/standard observable `L` signatures, matching DEM sampling +//! semantics. //! //! # Data-Oriented Design //! @@ -28,8 +29,8 @@ //! cache-efficient sampling: //! //! - **Probabilities**: Stored in a contiguous array for sequential access -//! - **Detector/`L` target indices**: CSR layout (offsets + flat data) for variable-length lists -//! - **Bit-packed outcomes**: Uses `u64` words for compact detector/`L` state +//! - **Detector/observable indices**: CSR layout (offsets + flat data) for variable-length lists +//! - **Bit-packed outcomes**: Uses `u64` words for compact detector/observable state //! //! # Example //! @@ -67,7 +68,7 @@ use pecos_random::{PecosRng, RngProbabilityExt}; use rand_core::Rng; use rayon::prelude::*; use smallvec::SmallVec; -use std::collections::BTreeMap; +use std::collections::{BTreeMap, BTreeSet}; use wide::u64x4; use super::types::combine_probabilities; @@ -76,13 +77,13 @@ use super::types::combine_probabilities; // DEM Mechanism (used during building) // ============================================================================ -/// A single fault mechanism with its detector and `L` target effects. +/// A single fault mechanism with its detector and standard observable `L` effects. /// Used during building, then converted to `SoA` layout. #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] struct DemMechanism { /// Sorted detector indices that flip when this mechanism fires. detectors: SmallVec<[u32; 4]>, - /// Sorted `L` target indices that flip when this mechanism fires. + /// Sorted standard observable `L` indices that flip when this mechanism fires. dem_outputs: SmallVec<[u32; 2]>, } @@ -213,7 +214,7 @@ pub struct SamplingEngine { detector_data: Vec, /// CSR-style offsets into `dem_output_data`. Length = `num_mechanisms` + 1. - /// These are Stim-compatible `L` DEM outputs. + /// These are standard observable `L` DEM outputs. dem_output_offsets: Vec, /// Flat array of `L` target indices. dem_output_data: Vec, @@ -237,10 +238,10 @@ impl SamplingEngine { self.num_detectors } - /// Number of observables in a pure Stim DEM. + /// Number of observables represented by `L` columns. /// - /// Parsed Stim DEMs do not carry PECOS tracked-operator metadata, so every - /// `L` output is treated as an observable. + /// When no PECOS tracked-operator metadata is present, every `L` output + /// is treated as an observable. #[must_use] pub fn num_observables(&self) -> usize { self.num_dem_outputs @@ -605,8 +606,8 @@ impl SamplingEngine { /// /// The sampler still reports per-DEM-output flip counts for every `L` /// output. `logical_error_count` and `undetectable_count` are computed - /// from the selected observable outputs only, so tracked-operator probes do - /// not affect decoder-style observable statistics. + /// from the selected observable outputs only, so unmeasured tracked + /// operators do not affect decoder-style observable statistics. #[must_use] pub fn sample_statistics_for_observable_indices( &self, @@ -1783,7 +1784,7 @@ impl SamplingStatistics { /// Builder for [`SamplingEngine`]. /// /// Constructs a [`SamplingEngine`] from a fault influence map, noise parameters, -/// and explicit detector/`L` target definitions. +/// and explicit detector/standard observable `L` definitions. pub(crate) struct SamplingEngineBuilder<'a> { influence_map: &'a DagFaultInfluenceMap, p1: f64, @@ -1883,7 +1884,8 @@ impl<'a> SamplingEngineBuilder<'a> { #[must_use] pub fn build(self) -> SamplingEngine { let num_detectors = self.detector_records.len(); - let num_influence_observables = self.influence_map.num_dem_outputs(); + let influence_observable_ids = self.influence_map.observable_ids(); + let num_influence_observables = self.influence_map.num_observables(); let num_dem_outputs = num_influence_observables.max(self.observable_records.len()); let num_im_measurements = self.influence_map.measurements.len(); let num_tc_measurements = self.num_tc_measurements.unwrap_or(num_im_measurements); @@ -1908,7 +1910,7 @@ impl<'a> SamplingEngineBuilder<'a> { Pauli::X, self.p_prep, im_to_tc.as_deref(), - 0, + &influence_observable_ids, num_tc_measurements, &mut aggregated, ); @@ -1921,7 +1923,7 @@ impl<'a> SamplingEngineBuilder<'a> { Pauli::X, self.p_meas, im_to_tc.as_deref(), - 0, + &influence_observable_ids, num_tc_measurements, &mut aggregated, ); @@ -1968,7 +1970,7 @@ impl<'a> SamplingEngineBuilder<'a> { loc_idx, self.p1, im_to_tc.as_deref(), - 0, + &influence_observable_ids, num_tc_measurements, &mut aggregated, ); @@ -1987,7 +1989,7 @@ impl<'a> SamplingEngineBuilder<'a> { loc_idx, p, im_to_tc.as_deref(), - 0, + &influence_observable_ids, num_tc_measurements, &mut aggregated, ); @@ -2005,7 +2007,7 @@ impl<'a> SamplingEngineBuilder<'a> { loc_indices[0], loc_indices[1], im_to_tc.as_deref(), - 0, + &influence_observable_ids, num_tc_measurements, &mut aggregated, ); @@ -2108,7 +2110,7 @@ impl<'a> SamplingEngineBuilder<'a> { pauli: Pauli, prob: f64, im_to_tc: Option<&[usize]>, - observable_id_offset: usize, + influence_observable_ids: &BTreeSet, num_tc_measurements: usize, aggregated: &mut BTreeMap, ) { @@ -2116,7 +2118,7 @@ impl<'a> SamplingEngineBuilder<'a> { loc_idx, pauli, im_to_tc, - observable_id_offset, + influence_observable_ids, num_tc_measurements, ); if !mechanism.is_empty() { @@ -2131,7 +2133,7 @@ impl<'a> SamplingEngineBuilder<'a> { loc_idx: usize, prob: f64, im_to_tc: Option<&[usize]>, - observable_id_offset: usize, + influence_observable_ids: &BTreeSet, num_tc_measurements: usize, aggregated: &mut BTreeMap, ) { @@ -2141,7 +2143,7 @@ impl<'a> SamplingEngineBuilder<'a> { loc_idx, pauli, im_to_tc, - observable_id_offset, + influence_observable_ids, num_tc_measurements, ); if !mechanism.is_empty() { @@ -2157,7 +2159,7 @@ impl<'a> SamplingEngineBuilder<'a> { loc1: usize, loc2: usize, im_to_tc: Option<&[usize]>, - observable_id_offset: usize, + influence_observable_ids: &BTreeSet, num_tc_measurements: usize, aggregated: &mut BTreeMap, ) { @@ -2173,14 +2175,14 @@ impl<'a> SamplingEngineBuilder<'a> { loc1, p, im_to_tc, - observable_id_offset, + influence_observable_ids, num_tc_measurements, )); effects2[p as usize] = Some(self.compute_mechanism( loc2, p, im_to_tc, - observable_id_offset, + influence_observable_ids, num_tc_measurements, )); } @@ -2203,7 +2205,7 @@ impl<'a> SamplingEngineBuilder<'a> { .clone() .unwrap_or_else(DemMechanism::empty) } else { - // Correlated: XOR the detector/`L` target effects + // Correlated: XOR the detector/standard observable effects let e1 = effects1[p1 as usize].as_ref(); let e2 = effects2[p2 as usize].as_ref(); xor_mechanisms(e1, e2) @@ -2217,13 +2219,13 @@ impl<'a> SamplingEngineBuilder<'a> { } } - /// Compute the mechanism (detector/`L` target effects) for a fault. + /// Compute the mechanism (detector/standard observable effects) for a fault. fn compute_mechanism( &self, loc_idx: usize, pauli: Pauli, im_to_tc: Option<&[usize]>, - observable_id_offset: usize, + influence_observable_ids: &BTreeSet, num_tc_measurements: usize, ) -> DemMechanism { // Get measurement indices that flip (in IM order) @@ -2286,8 +2288,13 @@ impl<'a> SamplingEngineBuilder<'a> { }) .collect(); - // Apply `L` target definitions (XOR of measurement outcomes) + // Apply standard observable `L` definitions (XOR of measurement outcomes) for (obs_id, records) in self.observable_records.iter().enumerate() { + #[allow(clippy::cast_possible_truncation)] // observable ID fits in u32 + let obs_id_u32 = obs_id as u32; + if influence_observable_ids.contains(&obs_id_u32) { + continue; + } let mut xor_result = false; for &offset in records { #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)] // measurement count fits in i32 @@ -2304,8 +2311,7 @@ impl<'a> SamplingEngineBuilder<'a> { } if xor_result { #[allow(clippy::cast_possible_truncation)] // `L` target ID fits in u32 - let obs_idx = (observable_id_offset + obs_id) as u32; - xor_toggle_u32(&mut dem_outputs, obs_idx); + xor_toggle_u32(&mut dem_outputs, obs_id_u32); } } dem_outputs.sort_unstable(); @@ -2326,7 +2332,7 @@ where } } -/// XORs two [`DemMechanism`]s (symmetric difference of detectors and `L` targets). +/// XORs two [`DemMechanism`]s (symmetric difference of detectors and standard observables). fn xor_mechanisms(a: Option<&DemMechanism>, b: Option<&DemMechanism>) -> DemMechanism { match (a, b) { (Some(m1), Some(m2)) => { diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs index 2912979a8..9ba7a0edf 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs @@ -238,7 +238,7 @@ impl ParsedDem { /// Parses a DEM from a string. /// - /// Supports both Stim and PECOS DEM formats. + /// Supports both standard and PECOS DEM formats. /// /// # Errors /// @@ -399,7 +399,7 @@ impl ParsedDem { /// /// # Semantics /// - /// In Stim's DEM format, `error(p) A ^ B` means that when the error fires + /// In DEM syntax, `error(p) A ^ B` means that when the error fires /// (with probability p), ALL components (A and B) flip together. The `^` /// separator is used for error tracking/decomposition but doesn't create /// independent firing - all components fire together as a single error. @@ -460,7 +460,7 @@ impl ParsedDem { /// /// # Note on decomposed errors /// - /// In Stim's DEM format, `error(p) D0 ^ D1` means that when the error fires + /// In DEM syntax, `error(p) D0 ^ D1` means that when the error fires /// (with probability p), BOTH D0 and D1 flip together. The `^` separator is /// used for error tracking/decomposition but doesn't affect sampling - all /// components fire together. @@ -616,14 +616,11 @@ impl FromStr for ParsedDem { } Self::record_metadata( &mut dem_outputs, - DemOutput::new(id) - .with_kind(crate::fault_tolerance::DemOutputKind::Observable), + DemOutput::new(id).with_kind(crate::fault_tolerance::DemOutputKind::Observable), ); } // Parse PECOS DEM-superset metadata declarations. - else if line.starts_with("pecos_observable") - || line.starts_with("pecos_tracked_op") - { + else if line.starts_with("pecos_observable") || line.starts_with("pecos_tracked_op") { let op = parse_pecos_dem_metadata_line(line) .map_err(|err| DemParseError::InvalidPecosMetadata(err.to_string()))?; if op.is_tracked_operator() { @@ -636,7 +633,7 @@ impl FromStr for ParsedDem { Self::record_metadata(&mut dem_outputs, op); } } - // PECOS extensions are explicit; ordinary Stim lines remain valid, + // PECOS extensions are explicit; ordinary DEM lines remain valid, // but unknown PECOS extension statements should not be silently // accepted as historical aliases. else if line.starts_with("pecos_") { @@ -1261,7 +1258,7 @@ error(0.02) D1 D2 #[test] fn test_decomposed_equivalent_to_simple() { - // In Stim's DEM format, these should be equivalent for sampling: + // In DEM syntax, these should be equivalent for sampling: // - error(0.1) D0 D1: D0 and D1 flip together with p=0.1 // - error(0.1) D0 ^ D1: D0 and D1 flip together with p=0.1 (^ is for decomposition tracking) let dem1 = ParsedDem::from_str("error(0.1) D0 D1").unwrap(); diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs index 180ac230a..5689c1a2c 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs @@ -201,11 +201,20 @@ fn dem_outputs_from_records( for (record_id, records) in observable_records.iter().enumerate() { let dem_output_id = record_id; if dem_output_id < targets.len() { - #[allow(clippy::cast_possible_truncation)] // DEM output count fits in u32 - { - targets[dem_output_id] = Some( - DemOutput::new(dem_output_id as u32).with_records(records.iter().copied()), - ); + if let Some(target) = &mut targets[dem_output_id] { + if target.records.is_empty() { + target.records = DemOutput::new(target.id) + .with_records(records.iter().copied()) + .records; + } + target.kind.get_or_insert(DemOutputKind::Observable); + } else { + #[allow(clippy::cast_possible_truncation)] // DEM output count fits in u32 + { + targets[dem_output_id] = Some( + DemOutput::new(dem_output_id as u32).with_records(records.iter().copied()), + ); + } } } } @@ -248,7 +257,9 @@ fn merge_dem_output_metadata( let tracked_op_labels = labels_from_dem_outputs(&labels.tracked_ops); if labels.tracked_op_labels.len() < tracked_op_labels.len() { - labels.tracked_op_labels.resize(tracked_op_labels.len(), None); + labels + .tracked_op_labels + .resize(tracked_op_labels.len(), None); } for (idx, label) in tracked_op_labels.into_iter().enumerate() { if labels.tracked_op_labels[idx].is_none() { @@ -363,15 +374,13 @@ impl DemSampler { }; let observables_json = { use pecos_num::graph::Attribute; - circuit - .get_attr("observables") - .and_then(|a| { - if let Attribute::String(s) = a { - Some(s.clone()) - } else { - None - } - }) + circuit.get_attr("observables").and_then(|a| { + if let Attribute::String(s) = a { + Some(s.clone()) + } else { + None + } + }) }; let num_meas = { use pecos_num::graph::Attribute; @@ -512,15 +521,15 @@ impl DemSampler { self.labels.tracked_ops.iter().flatten().count() } - /// DEM output indices classified as observables. + /// Standard observable `L` IDs selected from this sampler. #[must_use] - pub fn observable_dem_output_indices(&self) -> Vec { + pub fn observable_ids(&self) -> Vec { (0..self.num_dem_outputs).collect() } - /// DEM output indices classified as tracked operators. + /// PECOS tracked-operator IDs selected from this sampler. #[must_use] - pub fn tracked_operator_dem_output_indices(&self) -> Vec { + pub fn tracked_operator_ids(&self) -> Vec { Vec::new() } @@ -531,7 +540,7 @@ impl DemSampler { /// existing mask-based paths. #[must_use] pub fn observable_dem_output_mask(&self) -> u64 { - self.observable_dem_output_indices() + self.observable_ids() .into_iter() .filter(|&idx| idx < u64::BITS as usize) .fold(0u64, |acc, idx| acc | (1u64 << idx)) @@ -719,7 +728,7 @@ impl DemSampler { num_shots: usize, rng: &mut R, ) -> super::dem_sampler::SamplingStatistics { - let observable_indices = self.observable_dem_output_indices(); + let observable_indices = self.observable_ids(); self.inner .sample_statistics_with_rng_for_observable_indices(num_shots, rng, &observable_indices) } @@ -736,7 +745,7 @@ impl DemSampler { num_shots: usize, seed: u64, ) -> super::dem_sampler::SamplingStatistics { - let observable_indices = self.observable_dem_output_indices(); + let observable_indices = self.observable_ids(); self.inner .sample_statistics_for_observable_indices(num_shots, seed, &observable_indices) } @@ -821,7 +830,7 @@ impl<'a> DemSamplerBuilder<'a> { /// Request detector-event output with the given detector/DEM output definitions. /// - /// Detector records use Stim-style negative offsets: `[-1]` means "the last + /// Detector records use DEM-style negative offsets: `[-1]` means "the last /// measurement", `[-3, -1]` means "XOR of the last and third-to-last." #[must_use] pub fn with_detectors( @@ -892,8 +901,9 @@ impl<'a> DemSamplerBuilder<'a> { /// Extract annotations from a [`DagCircuit`] and configure the sampler. /// /// Detector annotations are mapped to auto-detected detector indices. - /// Observables are converted to measurement-record outputs. Operators are - /// tracked through PECOS metadata only. + /// Observables are converted to measurement-record outputs. Tracked + /// operators remain unmeasured Pauli-operator annotations and are carried + /// through PECOS metadata only. #[must_use] pub fn with_circuit_annotations(mut self, circuit: &pecos_quantum::DagCircuit) -> Self { use pecos_quantum::AnnotationKind; @@ -1553,6 +1563,48 @@ mod tests { ); } + #[test] + fn detector_mode_does_not_double_apply_annotation_observable_records() { + let mut circuit = DagCircuit::new(); + circuit.pz(&[0]); + let meas = circuit.mz(&[0]); + circuit.observable_labeled("obs0", &[meas[0]]); + + let im = InfluenceBuilder::new(&circuit) + .with_circuit_annotations(&circuit) + .build(); + + let sampler = DemSamplerBuilder::new(&im) + .with_noise(0.0, 0.0, 1.0, 0.0) + .with_detectors(Vec::new(), vec![vec![-1]]) + .build() + .unwrap(); + + assert_eq!(sampler.num_dem_outputs(), 1); + assert_eq!(sampler.num_observables(), 1); + assert_eq!(sampler.num_tracked_ops(), 0); + assert_eq!( + sampler.labels().dem_outputs[0] + .as_ref() + .unwrap() + .label + .as_deref(), + Some("obs0") + ); + assert_eq!( + sampler.labels().dem_outputs[0] + .as_ref() + .unwrap() + .records + .as_slice(), + &[-1] + ); + + let mut rng = PecosRng::seed_from_u64(42); + let (_detectors, observables) = sampler.sample(&mut rng); + assert_eq!(observables, vec![true]); + } + #[test] fn from_detector_error_model_preserves_observable_and_tracked_operator_split() { use super::super::builder::DemBuilder; @@ -1626,17 +1678,11 @@ mod tests { let dem = DemBuilder::from_circuit(&circuit, 0.03, 0.0, 0.02, 0.0); let sampler = DemSampler::from_detector_error_model(&dem); - assert_eq!(sampler.observable_dem_output_indices(), vec![0]); - assert_eq!(sampler.tracked_operator_dem_output_indices(), Vec::::new()); + assert_eq!(sampler.observable_ids(), vec![0]); + assert_eq!(sampler.tracked_operator_ids(), Vec::::new()); assert_eq!(sampler.observable_dem_output_mask(), 1); - assert_eq!( - sampler.observable_mask_from_dem_output_flips(&[false]), - 0 - ); - assert_eq!( - sampler.observable_mask_from_dem_output_flips(&[true]), - 1 - ); + assert_eq!(sampler.observable_mask_from_dem_output_flips(&[false]), 0); + assert_eq!(sampler.observable_mask_from_dem_output_flips(&[true]), 1); } #[test] diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs index 0fa8ab93f..161a2e73a 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs @@ -17,23 +17,32 @@ //! //! # Terminology //! -//! Stim DEM syntax calls `L` entries logical observables. PECOS keeps that -//! namespace reserved for measurement-record observables only. Tracked Pauli -//! operators are PECOS metadata with their own ID space so decoders can ignore -//! them while PECOS tools can still inspect them. +//! - **Detectors** are syndrome bits defined by measurement-record parity. +//! - **Observables** are values observed through measurements. In a DEM they are +//! defined by measurement records and rendered as standard `L` observable +//! outputs. +//! - **Tracked operators** are not measured values and are not applied to the +//! simulated computation. They are Pauli operators annotated at a circuit point +//! (for example a logical operator, stabilizer, or other Pauli of interest); +//! PECOS reports whether each fault event anticommutes with, and therefore +//! would flip, that operator under propagation. +//! +//! PECOS keeps the standard `L` namespace reserved for measurement-record +//! observables only. Tracked Pauli operators are PECOS metadata with their own +//! ID space, so decoders can ignore them while PECOS tools can still inspect +//! them. //! //! # Output Formats //! //! The DEM supports two output formats: //! -//! - [`DetectorErrorModel::to_string()`] - Non-decomposed format matching Stim's -//! `decompose_errors=False` output. Each mechanism is output once with its -//! combined probability. +//! - [`DetectorErrorModel::to_string()`] - Non-decomposed format. Each +//! mechanism is output once with its combined probability. //! -//! - [`DetectorErrorModel::to_string_decomposed()`] - Decomposed format matching -//! Stim's `decompose_errors=True` output. Hyperedge errors (3+ detectors) are -//! decomposed into graphlike components, and 2-detector mechanisms may have -//! multiple representations for decoder compatibility. +//! - [`DetectorErrorModel::to_string_decomposed()`] - Decomposed format. +//! Hyperedge errors (3+ detectors) are decomposed into graphlike components, +//! and 2-detector mechanisms may have multiple representations for decoder +//! compatibility. //! //! Decomposed errors use the `^` separator to indicate XOR composition: //! @@ -512,8 +521,7 @@ pub struct FaultMechanism { pub detectors: SmallVec<[u32; 4]>, /// DEM `L` target indices that flip together (sorted). /// - /// The field name follows Stim's DEM-output terminology. - /// New code should treat these as `L` target output channels. + /// New code should treat these as standard observable `L` output channels. pub dem_outputs: SmallVec<[u32; 2]>, } @@ -802,19 +810,18 @@ impl DecomposedFault { /// # Algorithm /// /// Uses a detector-driven recursive search over graphlike components whose -/// detector sets are subsets of the hyperedge. This is closer to Stim's -/// decomposition strategy than the older fixed-width 2-part/3-part search, -/// and it allows decompositions into 4+ graphlike pieces when needed. +/// detector sets are subsets of the hyperedge. This is more general than the +/// older fixed-width 2-part/3-part search, and it allows decompositions into 4+ +/// graphlike pieces when needed. /// /// Decompositions are filtered to only include components whose detectors are -/// subsets of the original hyperedge's detectors, matching Stim's behavior of -/// not introducing extra detector symptoms. +/// subsets of the original hyperedge's detectors, so decomposition does not +/// introduce extra detector symptoms. /// /// # Selection /// /// The search returns the first valid decomposition found using a deterministic -/// ordering that prefers detector pairs before singlets, similar to Stim's -/// decompose pass over known graphlike symptoms. +/// ordering that prefers detector pairs before singlets. #[cfg(test)] fn find_hyperedge_decomposition( hyperedge: &FaultMechanism, @@ -1089,7 +1096,7 @@ fn convert_location_indices(location_indices: &[usize]) -> SmallVec<[u32; 2]> { .collect() } -/// Converts a measurement record offset (Stim-style) to an absolute measurement index. +/// Converts a DEM measurement-record offset to an absolute measurement index. /// /// Negative offsets count backward from the end of the measurement record /// (`-1` is the last measurement). Positive offsets are treated as absolute @@ -1162,11 +1169,12 @@ impl DetectorDef { // DEM Outputs // ============================================================================ -/// Metadata for a PECOS non-detector output. +/// Metadata for a non-detector output definition. /// -/// Observables are rendered as standard Stim `L` targets. Tracked operators +/// Observables are rendered as standard `L` targets. Tracked operators /// use the same metadata shape but live in a separate PECOS-only ID space and -/// are never rendered as `L`. +/// are never rendered as `L` because they are unmeasured Pauli-operator +/// annotations, not measurement-record observables. #[derive(Debug, Clone)] pub struct DemOutput { /// Unique ID within this output's ID space. @@ -1211,7 +1219,10 @@ impl DemOutput { /// Sets the measurement records. #[must_use] pub fn with_records(mut self, records: impl IntoIterator) -> Self { - self.records = records.into_iter().collect(); + self.records.clear(); + for record in records { + toggle_dem_output_record(&mut self.records, record); + } self.kind.get_or_insert(DemOutputKind::Observable); self } @@ -1261,6 +1272,23 @@ impl DemOutput { } } +fn merge_record_parity(existing: &mut SmallVec<[i32; 4]>, incoming: SmallVec<[i32; 4]>) { + for record in incoming { + toggle_dem_output_record(existing, record); + } +} + +fn toggle_dem_output_record(records: &mut SmallVec<[i32; 4]>, record: i32) { + if let Some(pos) = records + .iter() + .position(|&existing_record| existing_record == record) + { + records.remove(pos); + } else { + records.push(record); + } +} + /// Error returned when parsing or applying PECOS DEM metadata JSON. #[derive(Debug, Clone, PartialEq, Eq)] pub struct PecosDemMetadataError { @@ -1700,11 +1728,11 @@ pub(crate) fn parse_pecos_dem_metadata_line( payload.trim(), Some(DemOutputKind::Observable), ) - } else { - return Err(PecosDemMetadataError::new( - "missing PECOS DEM metadata prefix", - )); - }; + } else { + return Err(PecosDemMetadataError::new( + "missing PECOS DEM metadata prefix", + )); + }; if payload.is_empty() { return Err(PecosDemMetadataError::new(format!( "{prefix} is missing its JSON payload" @@ -1751,30 +1779,29 @@ fn parse_pecos_metadata_json(json: &str) -> Result Result, PecosDemMetadataError> { - let Some(values) = root.get(name) else { - return Ok(Vec::new()); + let parse_array = + |name: &str, kind: DemOutputKind| -> Result, PecosDemMetadataError> { + let Some(values) = root.get(name) else { + return Ok(Vec::new()); + }; + let values = values.as_array().ok_or_else(|| { + PecosDemMetadataError::new(format!("{name} metadata is not an array")) + })?; + values + .iter() + .enumerate() + .map(|(idx, value)| { + let mut output = parse_pecos_metadata_dem_output(idx, value)?; + output.kind = Some(kind); + if kind == DemOutputKind::TrackedOperator && !output.records.is_empty() { + return Err(PecosDemMetadataError::new(format!( + "tracked operator metadata {idx} cannot have measurement records" + ))); + } + Ok(output) + }) + .collect() }; - let values = values.as_array().ok_or_else(|| { - PecosDemMetadataError::new(format!("{name} metadata is not an array")) - })?; - values - .iter() - .enumerate() - .map(|(idx, value)| { - let mut output = parse_pecos_metadata_dem_output(idx, value)?; - output.kind = Some(kind); - if kind == DemOutputKind::TrackedOperator && !output.records.is_empty() { - return Err(PecosDemMetadataError::new(format!( - "tracked operator metadata {idx} cannot have measurement records" - ))); - } - Ok(output) - }) - .collect() - }; let parsed = ParsedPecosDemMetadata { observables: parse_array("observables", DemOutputKind::Observable)?, @@ -1928,7 +1955,7 @@ fn parse_pecos_metadata_dem_output( pub struct DetectorErrorModel { /// Detector definitions. pub detectors: Vec, - /// Measurement-record observables rendered as standard Stim `L` outputs. + /// Measurement-record observables rendered as standard `L` outputs. pub observables: Vec, /// PECOS tracked Pauli operators. /// @@ -1959,10 +1986,10 @@ impl DetectorErrorModel { /// Creates a DEM with pre-allocated capacity. #[must_use] - pub fn with_capacity(num_detectors: usize, num_dem_outputs: usize) -> Self { + pub fn with_capacity(num_detectors: usize, num_observables: usize) -> Self { Self { detectors: Vec::with_capacity(num_detectors), - observables: Vec::with_capacity(num_dem_outputs), + observables: Vec::with_capacity(num_observables), tracked_ops: Vec::new(), contributions: Vec::new(), graphlike_decomposable_counts: BTreeMap::new(), @@ -1987,7 +2014,10 @@ impl DetectorErrorModel { .unwrap_or(0) } - /// Returns the number of standard DEM `L` outputs. + /// Returns the number of standard DEM `L` observable outputs. + /// + /// This is a DEM-output alias for [`Self::num_observables`]. It does + /// not include PECOS tracked operators. #[inline] #[must_use] pub fn num_dem_outputs(&self) -> usize { @@ -2006,6 +2036,9 @@ impl DetectorErrorModel { } /// Returns standard DEM output definitions (`L` observables). + /// + /// This DEM-output accessor does not include PECOS tracked operators; + /// use [`Self::tracked_ops`] for those. #[inline] #[must_use] pub fn dem_outputs(&self) -> &[DemOutput] { @@ -2013,6 +2046,8 @@ impl DetectorErrorModel { } /// Returns mutable standard DEM output definitions (`L` observables). + /// + /// This DEM-output accessor does not include PECOS tracked operators. #[inline] #[must_use] pub fn dem_outputs_mut(&mut self) -> &mut [DemOutput] { @@ -2043,8 +2078,7 @@ impl DetectorErrorModel { self.contributions.len() } - /// Exports PECOS-only metadata that is not representable in standard Stim - /// DEM syntax. + /// Exports PECOS-only metadata that is not representable in standard DEM syntax. /// /// The standard DEM string remains decoder-compatible and uses ordinary /// `logical_observable L` declarations. This JSON form preserves the @@ -2113,27 +2147,19 @@ impl DetectorErrorModel { #[must_use] pub fn to_pecos_string(&self) -> String { let mut text = self.to_string(); - let observable_lines = self - .observables - .iter() - .map(|observable| { - let value = pecos_metadata_dem_output_value(observable); - let payload = serde_json::to_string(&value) - .expect("serializing PECOS observable metadata should not fail"); - format!("pecos_observable {payload}") - }); - let tracked_op_lines = self - .tracked_ops - .iter() - .map(|tracked_op| { - let value = pecos_metadata_dem_output_value(tracked_op); - let payload = serde_json::to_string(&value) - .expect("serializing PECOS tracked-op metadata should not fail"); - format!("pecos_tracked_op {payload}") - }); - let metadata_lines: Vec = observable_lines - .chain(tracked_op_lines) - .collect(); + let observable_lines = self.observables.iter().map(|observable| { + let value = pecos_metadata_dem_output_value(observable); + let payload = serde_json::to_string(&value) + .expect("serializing PECOS observable metadata should not fail"); + format!("pecos_observable {payload}") + }); + let tracked_op_lines = self.tracked_ops.iter().map(|tracked_op| { + let value = pecos_metadata_dem_output_value(tracked_op); + let payload = serde_json::to_string(&value) + .expect("serializing PECOS tracked-op metadata should not fail"); + format!("pecos_tracked_op {payload}") + }); + let metadata_lines: Vec = observable_lines.chain(tracked_op_lines).collect(); if metadata_lines.is_empty() { return text; @@ -2147,7 +2173,7 @@ impl DetectorErrorModel { /// Applies PECOS metadata embedded in extended DEM text. /// - /// Stim-compatible lines are ignored by this method. PECOS extension lines + /// Standard DEM lines are ignored by this method. PECOS extension lines /// are parsed and merged into the observable/tracked-op definitions. /// /// # Errors @@ -2162,9 +2188,7 @@ impl DetectorErrorModel { if line.is_empty() || line.starts_with('#') { continue; } - if line.starts_with("pecos_observable") - || line.starts_with("pecos_tracked_op") - { + if line.starts_with("pecos_observable") || line.starts_with("pecos_tracked_op") { self.apply_dem_output_metadata(parse_pecos_dem_metadata_line(line)?); } else if line.starts_with("pecos_") { return Err(PecosDemMetadataError::new(format!( @@ -2645,8 +2669,8 @@ impl DetectorErrorModel { } // Y-containing channels are always classified as YDecomposed for source - // tracking purposes. This matches Stim's behavior where Y channels - // contribute to decomposed output forms regardless of component structure. + // tracking purposes so they can contribute to decomposed output forms + // regardless of component structure. // // The combined effect is X XOR Z. When one is empty, the combined effect // is just the non-empty one. @@ -2794,12 +2818,49 @@ impl DetectorErrorModel { } } - /// Adds a standard Stim observable (`L`) definition. + /// Adds a standard DEM observable (`L`) definition. pub fn add_observable(&mut self, mut observable: DemOutput) { - observable.kind.get_or_insert(DemOutputKind::Observable); + observable.kind = Some(DemOutputKind::Observable); + if let Some(existing) = self + .observables + .iter_mut() + .find(|existing| existing.id == observable.id) + { + Self::merge_observable_definition(existing, observable); + return; + } self.observables.push(observable); } + fn merge_observable_definition(existing: &mut DemOutput, incoming: DemOutput) { + existing.kind = Some(DemOutputKind::Observable); + merge_record_parity(&mut existing.records, incoming.records); + + if let Some(incoming_pauli) = incoming.pauli { + if let Some(existing_pauli) = &existing.pauli { + debug_assert_eq!( + existing_pauli, &incoming_pauli, + "conflicting Pauli metadata for observable L{}", + existing.id + ); + } else { + existing.pauli = Some(incoming_pauli); + } + } + + if let Some(incoming_label) = incoming.label { + if let Some(existing_label) = &existing.label { + debug_assert_eq!( + existing_label, &incoming_label, + "conflicting labels for observable L{}", + existing.id + ); + } else { + existing.label = Some(incoming_label); + } + } + } + /// Adds a PECOS tracked operator definition. pub fn add_tracked_operator(&mut self, mut tracked_op: DemOutput) { tracked_op.kind = Some(DemOutputKind::TrackedOperator); @@ -2809,8 +2870,7 @@ impl DetectorErrorModel { /// Converts the DEM to a string in standard DEM format. /// /// Each fault mechanism is output with its total probability, with no - /// splitting into decomposed forms. This matches Stim's - /// `detector_error_model(decompose_errors=False)` output. + /// splitting into decomposed forms. /// /// Requires source tracking to be enabled and contributions to be populated. /// Use `build_with_source_tracking()` to create a DEM with contributions. @@ -3124,9 +3184,8 @@ impl DetectorErrorModel { .0 } - /// Converts the DEM to Stim format using source tracking (decomposed format). + /// Converts the DEM to decomposed text using source tracking. /// - /// This matches Stim's `detector_error_model(decompose_errors=True)` output. /// Fault mechanisms are split into direct and decomposed forms based on /// their source types (X/Z vs Y errors). /// @@ -3187,8 +3246,8 @@ impl DetectorErrorModel { }; // Process each tracked contribution individually, then regroup identical - // decomposed outputs. This is closer to Stim's decomposition pass, which - // rewrites each error class before merging identical rewritten targets. + // decomposed outputs. Rewriting each error class before merging keeps + // source-aware decompositions stable. for contrib in &self.contributions { if contrib.effect.is_empty() || contrib.probability <= 0.0 { continue; @@ -3451,6 +3510,59 @@ mod tests { ); } + #[test] + fn test_duplicate_observable_definitions_merge_records_by_parity() { + use pecos_core::pauli::constructors::X; + + let mut dem = DetectorErrorModel::new(); + dem.add_observable( + DemOutput::new(0) + .with_records([-1, -2]) + .with_pauli(X(0)) + .with_label("logical_z"), + ); + dem.add_observable( + DemOutput::new(0) + .with_records([-2, -3]) + .with_pauli(X(0)) + .with_label("logical_z"), + ); + + assert_eq!(dem.num_observables(), 1); + let observable = &dem.dem_outputs()[0]; + assert_eq!(observable.records.as_slice(), &[-1, -3]); + assert_eq!(observable.pauli.as_ref().unwrap().to_sparse_str(), "+X0"); + assert_eq!(observable.label.as_deref(), Some("logical_z")); + } + + #[test] + fn test_observable_records_are_stored_by_xor_parity() { + let mut dem = DetectorErrorModel::new(); + dem.add_observable(DemOutput::new(0).with_records([-1, -2, -1, -3])); + + assert_eq!(dem.dem_outputs()[0].records.as_slice(), &[-2, -3]); + } + + #[test] + #[cfg(debug_assertions)] + #[should_panic(expected = "conflicting labels for observable L0")] + fn test_duplicate_observable_definitions_reject_conflicting_labels() { + let mut dem = DetectorErrorModel::new(); + dem.add_observable(DemOutput::new(0).with_label("first")); + dem.add_observable(DemOutput::new(0).with_label("second")); + } + + #[test] + #[cfg(debug_assertions)] + #[should_panic(expected = "conflicting Pauli metadata for observable L0")] + fn test_duplicate_observable_definitions_reject_conflicting_paulis() { + use pecos_core::pauli::constructors::{X, Z}; + + let mut dem = DetectorErrorModel::new(); + dem.add_observable(DemOutput::new(0).with_pauli(X(0))); + dem.add_observable(DemOutput::new(0).with_pauli(Z(0))); + } + #[test] fn test_dem_output_kind_predicates_are_mutually_exclusive() { use pecos_core::pauli::constructors::X; @@ -3493,7 +3605,10 @@ mod tests { assert_eq!(recovered.num_dem_outputs(), 1); assert_eq!(recovered.num_tracked_ops(), 0); assert_eq!(recovered.dem_outputs()[0].id, 0); - assert_eq!(recovered.dem_outputs()[0].kind, Some(DemOutputKind::Observable)); + assert_eq!( + recovered.dem_outputs()[0].kind, + Some(DemOutputKind::Observable) + ); } #[test] @@ -3683,7 +3798,7 @@ mod tests { DemOutput::new(0) .with_kind(DemOutputKind::TrackedOperator) .with_pauli(Z(3)) - .with_label("probe_z3"), + .with_label("tracked_z3"), ); dem.add_direct_contribution(FaultMechanism::from_unsorted([0], [0]), 0.01); dem.add_direct_contribution(FaultMechanism::from_unsorted([], [1]), 0.02); @@ -3705,7 +3820,11 @@ mod tests { assert_eq!(recovered.num_dem_outputs(), 2); assert_eq!(recovered.num_tracked_ops(), 1); assert_eq!( - recovered.dem_outputs().iter().map(|op| op.id).collect::>(), + recovered + .dem_outputs() + .iter() + .map(|op| op.id) + .collect::>(), [0, 1] ); assert_eq!( @@ -3717,12 +3836,16 @@ mod tests { [0] ); assert_eq!( - recovered.tracked_ops()[0].pauli.as_ref().unwrap().to_sparse_str(), + recovered.tracked_ops()[0] + .pauli + .as_ref() + .unwrap() + .to_sparse_str(), "+Z3" ); assert_eq!( recovered.tracked_ops()[0].label.as_deref(), - Some("probe_z3") + Some("tracked_z3") ); } diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index 5ebbc1060..65d37fc09 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -36,10 +36,10 @@ use pecos_core::pauli::pauli_string::PauliString; use pecos_core::{Pauli, QubitId}; use pecos_quantum::{AnnotationKind, TickCircuit}; use pecos_random::{PecosRng, RngExt}; +use pecos_simulators::CliffordGateable; use pecos_simulators::measurement_sampler::{MeasurementKind, SampleResult}; use pecos_simulators::pauli_prop::PauliProp; use pecos_simulators::symbolic_sparse_stab::MeasurementHistory; -use pecos_simulators::CliffordGateable; use std::collections::{BTreeSet, HashMap}; use std::fmt; @@ -2625,7 +2625,7 @@ mod tests { fn test_catalog_keeps_observables_and_tracked_ops_distinct() { let mut tc = TickCircuit::new(); tc.tick().h(&[QubitId(0)]); - tc.pauli_operator_labeled("z_probe", PauliString::z(0)); + tc.pauli_operator_labeled("tracked_z0", PauliString::z(0)); tc.set_meta( "detectors", pecos_quantum::Attribute::String("[]".to_string()), @@ -2673,10 +2673,12 @@ mod tests { assert_eq!(z_fault.affected_tracked_ops, Vec::::new()); let configs: Vec<_> = catalog.fault_configurations(1).collect(); - assert!(configs - .iter() - .any(|config| config.affected_tracked_ops.as_slice() == [0] - && config.affected_observables.is_empty())); + assert!( + configs + .iter() + .any(|config| config.affected_tracked_ops.as_slice() == [0] + && config.affected_observables.is_empty()) + ); } #[test] diff --git a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs index d0a381ac1..d24ba4c95 100644 --- a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs @@ -48,20 +48,44 @@ use std::collections::BinaryHeap; /// strings tracked for flipping via backward propagation. The difference /// is role and readout: /// -/// | Kind | Pauli | Readout | API | -/// |------|-------|---------|-----| -/// | Detector | Z on measured qubits | measurement XOR = 0 | `dag.detector(&[...])` | -/// | Observable | Z on measured qubits | measurement XOR | `dag.observable(&[...])` | -/// | Operator | user-specified | propagation only | `dag.pauli_operator(&[...])` | +/// | Kind | Meaning | Readout | API | +/// |------|---------|---------|-----| +/// | Detector | Syndrome parity from measurements | measurement XOR = 0 | `dag.detector(&[...])` | +/// | Observable | Standard `L` output from measurements | measurement XOR | `dag.observable(&[...])` | +/// | Tracked operator | User Pauli operator annotated at a circuit point | fault anticommutes with operator | `dag.pauli_operator(&[...])` | +/// +/// Observables and tracked operators both use backward Pauli propagation, but +/// they are not the same concept. Observables are values observed through +/// measurements, are defined by measurement records, and are decoder-visible +/// `L` outputs. Tracked operators are not measured and are not applied to the +/// computation; they ask whether a fault would flip a Pauli operator placed as +/// an annotation in the circuit, such as a logical operator, stabilizer, or +/// other Pauli of interest. They live in a separate PECOS-only namespace. pub use pecos_core::PauliString; +struct NonDetectorOutputTarget { + metadata: DemOutputMetadata, + terms: Vec, +} + +struct PauliPropagationTerm { + pauli: PauliString, + start_node: Option, +} + pub struct InfluenceBuilder<'a> { dag: &'a pecos_quantum::DagCircuit, - /// Pauli operators to track for flipping, with optional start position. - /// `None` means propagate from circuit end; `Some(node)` means propagate - /// from that DAG node's topological position. - /// (`metadata`, meta-gate node) - pauli_operators: Vec<(DemOutputMetadata, Option)>, + /// Non-detector parity outputs to track for flipping. + /// + /// This internal list contains both standard observables and PECOS tracked + /// operators. The metadata kind is the authority for which public namespace + /// each entry belongs to; callers should not infer that from the raw index. + /// + /// Each entry has one metadata item and one or more propagation terms. + /// Multiple terms accumulate into the same output index, which is needed + /// for measurement-record observables whose measurements occur at different + /// circuit positions. + non_detector_outputs: Vec, } impl<'a> InfluenceBuilder<'a> { @@ -70,37 +94,37 @@ impl<'a> InfluenceBuilder<'a> { pub fn new(dag: &'a pecos_quantum::DagCircuit) -> Self { Self { dag, - pauli_operators: Vec::new(), + non_detector_outputs: Vec::new(), } } /// Add a tracked X operator (X on all specified qubits). #[must_use] pub fn with_x(mut self, qubits: &[usize]) -> Self { - self.pauli_operators.push(( + self.push_single_term_output( DemOutputMetadata::tracked_operator(PauliString::xs(qubits)), None, - )); + ); self } /// Add a tracked Z operator (Z on all specified qubits). #[must_use] pub fn with_z(mut self, qubits: &[usize]) -> Self { - self.pauli_operators.push(( + self.push_single_term_output( DemOutputMetadata::tracked_operator(PauliString::zs(qubits)), None, - )); + ); self } /// Add a tracked Y operator (Y on all specified qubits). #[must_use] pub fn with_y(mut self, qubits: &[usize]) -> Self { - self.pauli_operators.push(( + self.push_single_term_output( DemOutputMetadata::tracked_operator(PauliString::ys(qubits)), None, - )); + ); self } @@ -117,16 +141,26 @@ impl<'a> InfluenceBuilder<'a> { /// ``` #[must_use] pub fn with_pauli_operator(mut self, pauli: PauliString) -> Self { - self.pauli_operators - .push((DemOutputMetadata::tracked_operator(pauli), None)); + self.push_single_term_output(DemOutputMetadata::tracked_operator(pauli), None); self } + fn push_single_term_output(&mut self, metadata: DemOutputMetadata, start_node: Option) { + self.non_detector_outputs.push(NonDetectorOutputTarget { + terms: vec![PauliPropagationTerm { + pauli: metadata.pauli.clone(), + start_node, + }], + metadata, + }); + } + /// Extract observable and tracked-operator annotations from the circuit. /// /// Observable annotations define logical observables via measurement records. - /// For backward propagation, each observable is converted to a Z-type Pauli - /// on the measured qubits, starting from the latest measurement node. + /// For backward propagation, each referenced measurement contributes its + /// own Z-type propagation term starting at that measurement node. The terms + /// accumulate into the same observable `L` output. /// /// Operator annotations have a corresponding `PauliOperatorMeta` node /// that marks their time position. @@ -148,35 +182,31 @@ impl<'a> InfluenceBuilder<'a> { for ann in circuit.annotations() { match &ann.kind { pecos_quantum::AnnotationKind::Observable { measurement_nodes } => { - // Convert measurement-based observable to Z-Pauli on measured qubits. - // Backward propagation starts from the latest measurement node. - let mut qubits = Vec::new(); - let mut latest_node = None; + let mut terms = Vec::new(); for &meas_node in measurement_nodes { if let Some(gate) = circuit.gate(meas_node) { - for q in &gate.qubits { - qubits.push(q.index()); - } + let qubits: Vec = + gate.qubits.iter().map(|q| q.index()).collect(); + terms.push(PauliPropagationTerm { + pauli: PauliString::zs(&qubits), + start_node: Some(meas_node), + }); } - latest_node = Some( - latest_node.map_or(meas_node, |prev: usize| prev.max(meas_node)), - ); } - let pauli = PauliString::zs(&qubits); - self.pauli_operators.push(( - DemOutputMetadata::observable(pauli) + self.non_detector_outputs.push(NonDetectorOutputTarget { + metadata: DemOutputMetadata::observable(ann.pauli.clone()) .with_optional_label(ann.label.clone()), - latest_node, - )); + terms, + }); } pecos_quantum::AnnotationKind::Operator => { let meta_node = meta_nodes.get(operator_idx).copied(); operator_idx += 1; - self.pauli_operators.push(( + self.push_single_term_output( DemOutputMetadata::tracked_operator(ann.pauli.clone()) .with_optional_label(ann.label.clone()), meta_node, - )); + ); } pecos_quantum::AnnotationKind::Detector { .. } => { // Detectors handled separately by DemSamplerBuilder @@ -403,33 +433,28 @@ impl<'a> InfluenceBuilder<'a> { }); } - // Add tracked Pauli operators in their PECOS tracked-op namespace. - let num_detectors = detectors.len(); - let num_tracked_ops = self.pauli_operators.len(); - // Build the influence structure using backward propagation - let mut recorder = - CompoundRecorder::new(map.locations.len(), num_detectors, num_tracked_ops); + let mut recorder = CompoundRecorder::new(map.locations.len()); // Propagate from each detector Self::propagate_detectors(propagator, info, detectors, &mut recorder); - // Propagate from tracked Pauli operators. - self.propagate_tracked_ops(propagator, &mut recorder); + // Propagate from non-detector DEM outputs. + self.propagate_non_detector_outputs(propagator, &mut recorder); // Convert to SoA format map.influences = recorder.into_soa(); // Store DEM-output labels map.dem_output_labels = self - .pauli_operators + .non_detector_outputs .iter() - .map(|(metadata, _)| metadata.label.clone()) + .map(|output| output.metadata.label.clone()) .collect(); map.dem_output_metadata = self - .pauli_operators + .non_detector_outputs .iter() - .map(|(metadata, _)| metadata.clone()) + .map(|output| output.metadata.clone()) .collect(); map @@ -571,13 +596,13 @@ impl<'a> InfluenceBuilder<'a> { } } - /// Propagate backward from tracked Pauli operators. + /// Propagate backward from non-detector DEM outputs. /// - /// If a Pauli operator has a corresponding `PauliOperatorMeta` node in the - /// DAG, propagation starts from that node's topological position. Otherwise - /// (e.g. operators added via `with_z`/`with_x` without a circuit annotation), - /// propagation walks from the circuit end. - fn propagate_tracked_ops( + /// If a propagation term has a corresponding DAG node, propagation starts + /// from that node's topological position. Otherwise (e.g. operators added + /// via `with_z`/`with_x` without a circuit annotation), propagation walks + /// from the circuit end. + fn propagate_non_detector_outputs( &self, propagator: &DagPropagator<'_>, recorder: &mut CompoundRecorder, @@ -589,35 +614,37 @@ impl<'a> InfluenceBuilder<'a> { let mut active_qubits = vec![false; max_qubit + 1]; let mut heap = BinaryHeap::new(); - for (dem_output_idx, (metadata, meta_node)) in self.pauli_operators.iter().enumerate() { - let mut prop = PauliProp::new(); - - for &(pauli, qubit) in metadata.pauli.paulis() { - use pecos_core::Pauli; - let q = qubit.index(); - match pauli { - Pauli::X => prop.track_x(&[q]), - Pauli::Y => prop.track_y(&[q]), - Pauli::Z => prop.track_z(&[q]), - Pauli::I => {} + for (dem_output_idx, output) in self.non_detector_outputs.iter().enumerate() { + for term in &output.terms { + let mut prop = PauliProp::new(); + + for &(pauli, qubit) in term.pauli.paulis() { + use pecos_core::Pauli; + let q = qubit.index(); + match pauli { + Pauli::X => prop.track_x(&[q]), + Pauli::Y => prop.track_y(&[q]), + Pauli::Z => prop.track_z(&[q]), + Pauli::I => {} + } } - } - - // Resolve the meta-gate node to its topological position. - // None means no positional bound (walk from circuit end). - let start_pos = meta_node.map(|node| propagator.topo_position(node)); - Self::propagate_observable( - propagator, - &prop, - dem_output_idx, - false, // is_detector = false (this is a DEM output) - recorder, - &mut visited, - &mut active_qubits, - &mut heap, - start_pos, - ); + // Resolve the term's node to its topological position. + // None means no positional bound (walk from circuit end). + let start_pos = term.start_node.map(|node| propagator.topo_position(node)); + + Self::propagate_observable( + propagator, + &prop, + dem_output_idx, + false, // is_detector = false (this is a DEM output) + recorder, + &mut visited, + &mut active_qubits, + &mut heap, + start_pos, + ); + } } } @@ -828,10 +855,6 @@ struct DetectorDef { /// Recorder for compound detector propagation. struct CompoundRecorder { num_locations: usize, - #[allow(dead_code)] - num_detectors: usize, - #[allow(dead_code)] - num_tracked_ops: usize, // Buckets for detector influences [loc_idx][pauli] -> Vec detector_x: Vec>, @@ -845,11 +868,9 @@ struct CompoundRecorder { } impl CompoundRecorder { - fn new(num_locations: usize, num_detectors: usize, num_tracked_ops: usize) -> Self { + fn new(num_locations: usize) -> Self { Self { num_locations, - num_detectors, - num_tracked_ops, detector_x: vec![Vec::new(); num_locations], detector_y: vec![Vec::new(); num_locations], detector_z: vec![Vec::new(); num_locations], @@ -864,9 +885,9 @@ impl CompoundRecorder { return; } match pauli { - Pauli::X => self.detector_x[loc_idx].push(detector_idx), - Pauli::Y => self.detector_y[loc_idx].push(detector_idx), - Pauli::Z => self.detector_z[loc_idx].push(detector_idx), + Pauli::X => toggle_bucket(&mut self.detector_x[loc_idx], detector_idx), + Pauli::Y => toggle_bucket(&mut self.detector_y[loc_idx], detector_idx), + Pauli::Z => toggle_bucket(&mut self.detector_z[loc_idx], detector_idx), Pauli::I => {} } } @@ -876,19 +897,26 @@ impl CompoundRecorder { return; } match pauli { - Pauli::X => self.dem_output_x[loc_idx].push(dem_output_idx), - Pauli::Y => self.dem_output_y[loc_idx].push(dem_output_idx), - Pauli::Z => self.dem_output_z[loc_idx].push(dem_output_idx), + Pauli::X => toggle_bucket(&mut self.dem_output_x[loc_idx], dem_output_idx), + Pauli::Y => toggle_bucket(&mut self.dem_output_y[loc_idx], dem_output_idx), + Pauli::Z => toggle_bucket(&mut self.dem_output_z[loc_idx], dem_output_idx), Pauli::I => {} } } - fn into_soa(self) -> super::propagator::dag::InfluencesSoA { + fn into_soa(mut self) -> super::propagator::dag::InfluencesSoA { use super::propagator::dag::InfluencesSoA; let mut soa = InfluencesSoA::with_capacity(self.num_locations); for loc_idx in 0..self.num_locations { + self.detector_x[loc_idx].sort_unstable(); + self.detector_y[loc_idx].sort_unstable(); + self.detector_z[loc_idx].sort_unstable(); + self.dem_output_x[loc_idx].sort_unstable(); + self.dem_output_y[loc_idx].sort_unstable(); + self.dem_output_z[loc_idx].sort_unstable(); + // Add detector influences for &det in &self.detector_x[loc_idx] { soa.detectors_x.push(det); @@ -918,6 +946,14 @@ impl CompoundRecorder { } } +fn toggle_bucket(bucket: &mut Vec, value: u32) { + if let Some(pos) = bucket.iter().position(|&existing| existing == value) { + bucket.remove(pos); + } else { + bucket.push(value); + } +} + #[cfg(test)] mod tests { use super::*; @@ -1039,11 +1075,11 @@ mod tests { assert_eq!(map.dem_output_metadata.len(), 2); // Observable comes first (annotations are processed in order) + assert_eq!(map.dem_output_metadata[0].kind, DemOutputKind::Observable); assert_eq!( - map.dem_output_metadata[0].kind, - DemOutputKind::Observable + map.dem_output_metadata[0].label.as_deref(), + Some("record_obs") ); - assert_eq!(map.dem_output_metadata[0].label.as_deref(), Some("record_obs")); // Tracked operator second assert_eq!( @@ -1053,4 +1089,157 @@ mod tests { assert_eq!(map.dem_output_metadata[1].label.as_deref(), Some("track_x")); assert_eq!(map.dem_output_metadata[1].pauli.to_sparse_str(), "+X0"); } + + #[test] + fn test_observable_measurements_propagate_from_their_own_nodes() { + use pecos_quantum::GateType; + + let mut dag = DagCircuit::new(); + dag.pz(&[0, 1]); + let early = dag.mz(&[0]); + dag.h(&[0]); + let late = dag.mz(&[1]); + dag.observable_labeled("split_time_obs", &[early[0], late[0]]); + + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + assert_eq!(map.num_observables(), 1); + + let post_early_h = map + .locations + .iter() + .enumerate() + .find(|(_, loc)| { + loc.gate_type == GateType::H + && loc.qubits.first().is_some_and(|q| q.index() == 0) + && !loc.before + }) + .map(|(idx, _)| idx) + .expect("H fault location after the early measurement"); + + for pauli in [Pauli::X, Pauli::Y, Pauli::Z] { + assert!( + map.get_observable_indices(post_early_h, pauli.as_u8()) + .is_empty(), + "faults after an already-recorded measurement must not flip that record" + ); + } + } + + #[test] + fn test_split_time_observable_fault_before_early_measurement_flips() { + // Circuit: PZ(0), PZ(1), MZ(0) [early], H(1), MZ(1) [late] + // Observable = MZ(0) XOR MZ(1) + // + // A prep fault on qubit 0 (after PZ(0), before MZ(0)) should flip the + // observable via the early measurement term. + use pecos_quantum::GateType; + + let mut dag = DagCircuit::new(); + dag.pz(&[0, 1]); + let early = dag.mz(&[0]); + dag.h(&[1]); + let late = dag.mz(&[1]); + dag.observable_labeled("split_obs", &[early[0], late[0]]); + + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + assert_eq!(map.num_observables(), 1); + + // Prep fault on qubit 0 (PZ after-gate location) should flip the + // observable because it propagates through the early MZ(0). + let prep_q0 = map + .locations + .iter() + .enumerate() + .find(|(_, loc)| { + loc.gate_type == GateType::PZ + && loc.qubits.first().is_some_and(|q| q.index() == 0) + && !loc.before + }) + .map(|(idx, _)| idx) + .expect("PZ(0) fault location"); + + // X fault after PZ propagates through MZ as a bit flip + assert!( + !map.get_observable_indices(prep_q0, Pauli::X.as_u8()) + .is_empty(), + "X fault before early measurement should flip observable" + ); + } + + #[test] + fn test_split_time_observable_fault_between_measurements_flips_late_only() { + // Circuit: PZ(0), PZ(1), MZ(0) [early], H(1), MZ(1) [late] + // Observable = MZ(0) XOR MZ(1) + // + // An H fault on qubit 1 (between the two measurements) should flip the + // observable via the late measurement term only. + use pecos_quantum::GateType; + + let mut dag = DagCircuit::new(); + dag.pz(&[0, 1]); + let early = dag.mz(&[0]); + dag.h(&[1]); + let late = dag.mz(&[1]); + dag.observable_labeled("split_obs", &[early[0], late[0]]); + + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + assert_eq!(map.num_observables(), 1); + + // H(1) fault location — between the two measurements, on qubit 1 + let h_q1 = map + .locations + .iter() + .enumerate() + .find(|(_, loc)| { + loc.gate_type == GateType::H + && loc.qubits.first().is_some_and(|q| q.index() == 1) + && !loc.before + }) + .map(|(idx, _)| idx) + .expect("H(1) fault location"); + + // X fault after H(1) becomes Z before MZ(1), which does NOT flip MZ. + // Z fault after H(1) becomes X before MZ(1), which DOES flip MZ. + assert!( + !map.get_observable_indices(h_q1, Pauli::X.as_u8()) + .is_empty() + || !map + .get_observable_indices(h_q1, Pauli::Z.as_u8()) + .is_empty(), + "at least one Pauli fault between measurements should flip the late term" + ); + } + + #[test] + fn test_duplicate_observable_terms_cancel_in_influence_map() { + let mut dag = DagCircuit::new(); + dag.pz(&[0]); + dag.h(&[0]); + let meas = dag.mz(&[0]); + dag.observable_labeled("duplicate_record_obs", &[meas[0], meas[0]]); + + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + + assert_eq!(map.num_observables(), 1); + for loc_idx in 0..map.locations.len() { + for pauli in [Pauli::X, Pauli::Y, Pauli::Z] { + assert!( + map.get_observable_indices(loc_idx, pauli.as_u8()) + .is_empty(), + "observable record XOR should cancel duplicate measurement terms" + ); + } + } + } } diff --git a/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs b/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs index 93ab21133..3ae316d02 100644 --- a/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs +++ b/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs @@ -44,8 +44,8 @@ use std::collections::BTreeMap; pub struct LookupDecoder { /// Syndrome -> most likely observable flip pattern. table: BTreeMap, Vec>, - /// DEM output IDs classified as observables. - observable_dem_outputs: Vec, + /// Standard observable `L` IDs in correction-vector order. + observable_ids: Vec, /// Maximum fault weight enumerated. max_weight: usize, /// Total probability mass accounted for (weight 0 through `max_weight`). @@ -72,8 +72,8 @@ impl LookupDecoder { /// 1-qubit, p/15 for 2-qubit). Idle gates with T1/T2 use biased noise. #[must_use] pub fn build(map: &DagFaultInfluenceMap, noise: &NoiseConfig, max_weight: usize) -> Self { - let observable_dem_outputs = observable_dem_output_indices(map); - let num_observables = observable_dem_outputs.len(); + let observable_ids = observable_ids(map); + let num_observables = observable_ids.len(); let loc_probs = compute_location_probs(&map.locations, noise); let locs = map.gate_fault_locations(); @@ -167,7 +167,11 @@ impl LookupDecoder { EventData { prob: ratio, detectors: event.detectors, - dem_outputs: event.dem_outputs, + observable_ids: event + .dem_outputs + .iter() + .filter_map(|&idx| map.observable_id_for_internal_dem_output(idx)) + .collect(), } }) .collect(); @@ -176,6 +180,11 @@ impl LookupDecoder { loc_events.push(event_data); } + // Accumulate syndrome probabilities separately from per-observable + // correction weights. This keeps probability accounting well-defined + // even for detector-only maps with zero observables. + let mut syndrome_probabilities: BTreeMap, f64> = BTreeMap::new(); + // Accumulate: syndrome -> per-observable (flip_prob, noflip_prob) let mut syndrome_data: BTreeMap, Vec<(f64, f64)>> = BTreeMap::new(); @@ -184,6 +193,7 @@ impl LookupDecoder { // Weight 0: no faults. Empty syndrome, no observable flips. { + syndrome_probabilities.insert(Vec::new(), base_prob); let entry = syndrome_data .entry(Vec::new()) .or_insert_with(|| vec![(0.0, 0.0); num_observables]); @@ -198,7 +208,7 @@ impl LookupDecoder { let combo_state = ComboState { prob: base_prob, detectors: Vec::new(), - dem_outputs: Vec::new(), + observable_ids: Vec::new(), }; for weight in 1..=max_weight { @@ -207,18 +217,13 @@ impl LookupDecoder { weight, 0, &combo_state, - &observable_dem_outputs, + &observable_ids, + &mut syndrome_probabilities, &mut syndrome_data, ); } - // Compute total accounted probability. - // For each syndrome, the total probability is flip + noflip for any single - // observable channel (they all see the same total probability for that syndrome). - let accounted_probability: f64 = syndrome_data - .values() - .map(|weights| weights.first().map_or(0.0, |&(f, nf)| f + nf)) - .sum(); + let accounted_probability: f64 = syndrome_probabilities.values().sum(); // Build ML decision table let table = syndrome_data @@ -234,7 +239,7 @@ impl LookupDecoder { Self { table, - observable_dem_outputs, + observable_ids, max_weight, accounted_probability, } @@ -255,7 +260,7 @@ impl LookupDecoder { } } else { DecoderResult { - corrections: vec![false; self.observable_dem_outputs.len()], + corrections: vec![false; self.observable_ids.len()], known_syndrome: false, detected, } @@ -295,13 +300,13 @@ impl LookupDecoder { /// Number of observable channels. #[must_use] pub fn num_observables(&self) -> usize { - self.observable_dem_outputs.len() + self.observable_ids.len() } - /// DEM output IDs classified as observables, in correction-vector order. + /// Standard observable `L` IDs in correction-vector order. #[must_use] - pub fn observable_dem_output_indices(&self) -> &[u32] { - &self.observable_dem_outputs + pub fn observable_ids(&self) -> &[u32] { + &self.observable_ids } /// Estimated upper bound on the probability mass NOT accounted for @@ -331,27 +336,27 @@ impl LookupDecoder { struct EventData { prob: f64, detectors: Vec, - dem_outputs: Vec, + observable_ids: Vec, } #[derive(Clone)] struct ComboState { prob: f64, detectors: Vec, - dem_outputs: Vec, + observable_ids: Vec, } impl ComboState { - /// Compose with a new event: XOR detectors/DEM outputs, multiply prob. + /// Compose with a new event: XOR detectors/observable IDs, multiply prob. fn compose(&self, event: &EventData) -> Self { let mut detectors = self.detectors.clone(); xor_into(&mut detectors, &event.detectors); - let mut dem_outputs = self.dem_outputs.clone(); - xor_into(&mut dem_outputs, &event.dem_outputs); + let mut observable_ids = self.observable_ids.clone(); + xor_into(&mut observable_ids, &event.observable_ids); Self { prob: self.prob * event.prob, detectors, - dem_outputs, + observable_ids, } } } @@ -394,19 +399,24 @@ fn enumerate_combos( remaining: usize, start_loc: usize, state: &ComboState, - observable_dem_outputs: &[u32], + observable_ids: &[u32], + syndrome_probabilities: &mut BTreeMap, f64>, syndrome_data: &mut BTreeMap, Vec<(f64, f64)>>, ) { if remaining == 0 { let mut syndrome = state.detectors.clone(); syndrome.sort_unstable(); + *syndrome_probabilities + .entry(syndrome.clone()) + .or_insert(0.0) += state.prob; + let entry = syndrome_data .entry(syndrome) - .or_insert_with(|| vec![(0.0, 0.0); observable_dem_outputs.len()]); + .or_insert_with(|| vec![(0.0, 0.0); observable_ids.len()]); - for (&observable_id, weights) in observable_dem_outputs.iter().zip(entry.iter_mut()) { - let flipped = state.dem_outputs.contains(&observable_id); + for (&observable_id, weights) in observable_ids.iter().zip(entry.iter_mut()) { + let flipped = state.observable_ids.contains(&observable_id); if flipped { weights.0 += state.prob; } else { @@ -424,7 +434,8 @@ fn enumerate_combos( remaining - 1, loc_idx + 1, &next_state, - observable_dem_outputs, + observable_ids, + syndrome_probabilities, syndrome_data, ); } @@ -454,18 +465,49 @@ fn gate_location_prob( 0.0 } -fn observable_dem_output_indices(map: &DagFaultInfluenceMap) -> Vec { - let num_dem_outputs = map.influences.max_dem_output_index().map_or(0, |i| i + 1); - if map.dem_output_metadata.is_empty() { - return (0..num_dem_outputs as u32).collect(); +fn observable_ids(map: &DagFaultInfluenceMap) -> Vec { + map.observable_ids().into_iter().collect() +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::fault_tolerance::InfluenceBuilder; + use pecos_core::pauli::constructors::X; + use pecos_quantum::DagCircuit; + + #[test] + fn observable_indices_use_compact_l_namespace_with_tracked_ops() { + let mut dag = DagCircuit::new(); + dag.pz(&[0]); + dag.pauli_operator_labeled("track_x", X(0)); + let meas = dag.mz(&[0]); + dag.observable_labeled("obs0", &[meas[0]]); + + let map = InfluenceBuilder::new(&dag) + .with_circuit_annotations(&dag) + .build(); + assert_eq!(map.num_tracked_ops(), 1); + assert_eq!(map.num_observables(), 1); + + let decoder = LookupDecoder::build(&map, &NoiseConfig::uniform(0.01), 1); + assert_eq!(decoder.observable_ids(), &[0]); } - map.dem_output_metadata - .iter() - .enumerate() - .filter_map(|(idx, metadata)| { - (idx < num_dem_outputs && metadata.kind == super::propagator::DemOutputKind::Observable) - .then_some(idx as u32) - }) - .collect() + #[test] + fn detector_only_decoder_accounts_probability_without_observables() { + let mut dag = DagCircuit::new(); + dag.pz(&[0, 1]); + dag.cx(&[(0, 1)]); + let meas = dag.mz(&[1]); + dag.detector(&[meas[0]]); + + let map = InfluenceBuilder::new(&dag).build(); + assert_eq!(map.num_observables(), 0); + + let decoder = LookupDecoder::build(&map, &NoiseConfig::uniform(0.01), 0); + assert_eq!(decoder.num_observables(), 0); + assert!(decoder.accounted_probability() > 0.0); + assert!(decoder.truncation_bound() < 1.0); + } } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator.rs b/crates/pecos-qec/src/fault_tolerance/propagator.rs index 2f130617b..5bee37eeb 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator.rs @@ -13,9 +13,10 @@ //! Pauli propagation infrastructure and fault analysis. //! //! This module provides bidirectional Pauli propagation through quantum circuits, -//! with specialized support for fault tolerance analysis. By propagating observables -//! backward from measurements and tracked Pauli operators, we can efficiently determine which faults -//! affect which detectors: +//! with specialized support for fault tolerance analysis. By propagating +//! detector/observable measurement parities and unmeasured tracked Pauli +//! operators backward through the circuit, we can efficiently determine which +//! faults affect which outputs: //! //! 1. **Speed up fault enumeration** - O(1) lookup instead of `O(circuit_depth)` propagation //! 2. **Build detector error models** - Direct mapping from faults to detectors @@ -43,10 +44,17 @@ //! let analyzer = DagFaultAnalyzer::new(&dag); //! let map = analyzer.build_influence_map(); //! -//! // O(1) lookup: which measurements does a fault at location L flip? -//! let (has_syndrome, flips_tracked_op) = map.classify_fault(0, 1); // loc 0, X fault +//! // O(1) lookup: which detector/non-detector outputs does a fault at location L flip? +//! let (has_syndrome, _flips_non_detector_output) = map.classify_fault(0, 1); // loc 0, X fault //! ``` //! +//! Observables and tracked operators are distinct. Observables are values +//! observed through measurement-record parities and become standard `L` +//! outputs in DEM text. Tracked operators are Pauli operators annotated at +//! circuit points; they are not measured and are not applied to the computation. +//! PECOS records whether each fault anticommutes with, and therefore would flip, +//! the propagated operator. +//! //! # Concept //! //! Instead of forward propagation: diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs b/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs index 04300f5a5..a18132066 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs @@ -32,6 +32,26 @@ //! - [`DagSpacetimeLocation`]: Identifies a fault location in a DAG circuit //! - [`DagFaultInfluenceMap`]: Cache-optimized influence map using CSR layout //! +//! # Output Terminology +//! +//! The influence map has one detector namespace plus one raw internal +//! non-detector-output namespace. That raw namespace is only a storage detail: +//! metadata maps each raw non-detector output to either a standard observable +//! (`L`) or a PECOS tracked operator. Decoder and sampler code should use +//! [`DagFaultInfluenceMap::observable_ids`], +//! [`DagFaultInfluenceMap::observable_id_for_internal_dem_output`], and +//! [`DagFaultInfluenceMap::tracked_op_id_for_internal_dem_output`] instead of +//! assuming raw indices are public `L` IDs. +//! +//! Observables and tracked operators differ by definition, not just by name. +//! Observables are values observed through measurement-record parities and are +//! visible to DEM decoders as standard `L` outputs. Tracked operators are +//! unmeasured Pauli operators annotated at a circuit point, such as logical +//! operators, stabilizers, or other Paulis of interest; the influence map +//! records whether a fault anticommutes with, and therefore would flip, the +//! propagated operator. They are PECOS metadata and are not measurement-record +//! observables. +//! //! # Example //! //! ``` @@ -48,7 +68,7 @@ //! let map = analyzer.build_influence_map(); //! //! // O(1) fault classification -//! let (has_syndrome, flips_dem_output) = map.classify_fault(0, 1); // loc 0, X fault +//! let (has_syndrome, _flips_non_detector_output) = map.classify_fault(0, 1); // loc 0, X fault //! ``` use super::{ @@ -59,7 +79,7 @@ use pecos_core::{PauliString, QuarterPhase, QubitId}; use pecos_quantum::DagCircuit; use pecos_simulators::PauliProp; use smallvec::SmallVec; -use std::collections::{BTreeMap, BinaryHeap}; +use std::collections::{BTreeMap, BTreeSet, BinaryHeap}; /// Reusable work buffers for propagation, avoiding per-call allocation. pub struct PropagationBuffers { @@ -351,13 +371,17 @@ pub struct InfluencesSoA { /// Detector indices flipped by Z faults (Pauli=3). pub detectors_z: CsrArray, - /// DEM `L` DEM-output indices flipped by X faults. + /// Internal non-detector output indices flipped by X faults. + /// + /// These raw indices may name either standard observables or PECOS tracked + /// operators. Use [`DagFaultInfluenceMap`] metadata helpers to map them into + /// the public `L` observable namespace or tracked-operator namespace. pub dem_outputs_x: CsrArray, - /// DEM `L` DEM-output indices flipped by Y faults. + /// Internal non-detector output indices flipped by Y faults. pub dem_outputs_y: CsrArray, - /// DEM `L` DEM-output indices flipped by Z faults. + /// Internal non-detector output indices flipped by Z faults. pub dem_outputs_z: CsrArray, } @@ -390,7 +414,13 @@ impl InfluencesSoA { } } - /// Returns the DEM-output indices for a location and Pauli type. + /// Returns raw internal non-detector output indices for a location and Pauli type. + /// + /// These indices are not necessarily standard `L` IDs. Callers that + /// need public observable IDs should use + /// [`DagFaultInfluenceMap::observable_id_for_internal_dem_output`]; callers + /// that need tracked-operator IDs should use + /// [`DagFaultInfluenceMap::tracked_op_id_for_internal_dem_output`]. #[inline] #[must_use] pub fn dem_outputs(&self, loc_idx: usize, pauli: Pauli) -> &[u32] { @@ -414,7 +444,7 @@ impl InfluencesSoA { } } - /// Returns whether the location has any DEM-output flips for the given Pauli. + /// Returns whether the location has any non-detector output flips for the given Pauli. #[inline] #[must_use] pub fn has_dem_output_flips(&self, loc_idx: usize, pauli: Pauli) -> bool { @@ -428,7 +458,7 @@ impl InfluencesSoA { /// Classifies a fault at the given location. /// - /// Returns (`has_syndrome`, `flips_dem_output`). + /// Returns (`has_syndrome`, `flips_non_detector_output`). #[inline] #[must_use] pub fn classify(&self, loc_idx: usize, pauli: Pauli) -> (bool, bool) { @@ -482,7 +512,7 @@ impl InfluencesSoA { } } - /// Returns the maximum raw DEM-output influence index, if any. + /// Returns the maximum raw non-detector output influence index, if any. /// /// When metadata is present, callers should use [`Self::num_dem_outputs`] /// for the standard observable `L` namespace and [`Self::num_tracked_ops`] @@ -542,15 +572,16 @@ pub struct DagFaultInfluenceMap { /// Empty for legacy circuits without MeasId on gates. pub meas_ids: Vec, - /// Optional labels for non-detector DEM outputs. - /// Indices match the DEM-output indices in `influences`. + /// Optional labels for non-detector parity outputs. + /// Indices match the raw non-detector output indices in `influences`. pub dem_output_labels: Vec>, /// Optional metadata for non-detector outputs tracked by backward propagation. /// - /// These entries are PECOS tracked operators unless explicitly marked as - /// observables by a specialized builder. Standard DEM `L` observables - /// should normally come from measurement-record metadata instead. + /// These entries may be standard observables or PECOS tracked operators. + /// The metadata kind is the authority for translating raw influence indices + /// into public namespaces; standard observables use compact `L` IDs and + /// tracked operators use their own compact PECOS-only IDs. pub dem_output_metadata: Vec, } @@ -571,7 +602,7 @@ impl DagFaultInfluenceMap { /// Classifies a fault at the given location index. /// - /// Returns (`has_syndrome`, `flips_dem_output`). + /// Returns (`has_syndrome`, `flips_non_detector_output`). #[inline] #[must_use] pub fn classify_fault(&self, loc_idx: usize, pauli: u8) -> (bool, bool) { @@ -585,7 +616,11 @@ impl DagFaultInfluenceMap { self.influences.detectors(loc_idx, Pauli::from_u8(pauli)) } - /// Returns all non-detector DEM output indices flipped by a fault. + /// Returns all raw non-detector output indices flipped by a fault. + /// + /// Raw indices are an internal storage detail shared by observables and + /// tracked operators. Prefer [`Self::get_observable_indices`] or + /// [`Self::get_tracked_op_indices`] when a public namespace is needed. #[inline] #[must_use] pub fn get_dem_output_indices(&self, loc_idx: usize, pauli: u8) -> &[u32] { @@ -593,6 +628,9 @@ impl DagFaultInfluenceMap { } /// Returns the number of standard DEM `L` observable outputs. + /// + /// This is a DEM-output alias for [`Self::num_observables`]. It does + /// not include PECOS tracked operators. #[must_use] pub fn num_dem_outputs(&self) -> usize { if self.dem_output_metadata.is_empty() { @@ -610,6 +648,18 @@ impl DagFaultInfluenceMap { self.num_dem_outputs() } + /// Returns the standard observable `L` IDs present in this map. + /// + /// Tracked operators share internal propagation storage but never appear in + /// this set. Public decoder and sampler paths should use this namespace + /// rather than raw internal DEM-output indices. + #[must_use] + pub fn observable_ids(&self) -> BTreeSet { + (0..self.num_dem_outputs()) + .filter_map(|idx| u32::try_from(idx).ok()) + .collect() + } + /// Returns the number of PECOS tracked operators. #[must_use] pub fn num_tracked_ops(&self) -> usize { @@ -738,7 +788,7 @@ impl DagFaultInfluenceMap { /// The exported DEM-output arrays contain only standard observable `L` /// outputs. PECOS tracked operators share the internal backward-propagation /// storage but are intentionally filtered out here so decoder-oriented GPU - /// code cannot count tracked probes as logical errors. + /// code cannot count tracked operators as logical errors. /// /// Returns all CSR arrays needed to construct a GPU influence sampler: /// (`num_locations`, `num_detectors`, `num_dem_outputs`, @@ -836,12 +886,12 @@ impl DagFaultInfluenceMap { } } -/// Role of a non-detector DEM output under backward Pauli propagation. +/// Role of a non-detector output under backward Pauli propagation. #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] pub enum DemOutputKind { - /// An observable DEM output. + /// A standard `L` observable defined by measurement records. Observable, - /// A tracked operator annotation with no observable readout. + /// An unmeasured Pauli-operator annotation, separate from measurement records. TrackedOperator, } @@ -866,16 +916,21 @@ impl DemOutputKind { } } -/// Metadata for a PECOS non-detector DEM output. +/// Metadata for a PECOS non-detector output. /// -/// Stim-compatible DEM strings only have `L` markers. PECOS keeps this -/// richer record alongside the DEM so callers can tell whether a marker came -/// from an observable or from a tracked Pauli operator annotation. +/// Standard DEM text only has `L` observable markers. PECOS keeps this richer +/// record alongside the DEM so callers can distinguish those measurement-record +/// observables from tracked Pauli operators, which live in a separate +/// PECOS-only namespace. #[derive(Debug, Clone, PartialEq, Eq)] pub struct DemOutputMetadata { /// The output role. pub kind: DemOutputKind, /// Pauli string whose flip is tracked. + /// + /// For observables this is the Pauli associated with the measurement-record + /// observable. For tracked operators this is the unmeasured Pauli operator + /// annotated at a circuit point. pub pauli: PauliString, /// Optional user label. pub label: Option, @@ -1765,9 +1820,9 @@ impl<'a> DagFaultAnalyzer<'a> { /// 1. Topological position (to respect causal dependencies) /// 2. Qubit index (to break ties for concurrent/independent measurements) /// - /// This ensures the measurement ordering matches Stim's convention where - /// measurements on lower-indexed qubits appear first when they're in the - /// same "layer" of the circuit. + /// This gives deterministic measurement ordering where measurements on + /// lower-indexed qubits appear first when they are in the same "layer" of + /// the circuit. #[must_use] /// Extract measurements with optional MeasId IDs. /// diff --git a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs index 5ef4e6293..5acbbdd38 100644 --- a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs +++ b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs @@ -267,9 +267,9 @@ fn xor_sets(a: &BTreeSet, b: &BTreeSet) -> BTreeSet { mod tests { use super::*; use crate::fault_tolerance::fault_sampler::{ - build_fault_catalog, FaultCatalog, StochasticNoiseParams, + FaultCatalog, StochasticNoiseParams, build_fault_catalog, }; - use pecos_core::{gate_type::GateType, QubitId}; + use pecos_core::{QubitId, gate_type::GateType}; use pecos_quantum::TickCircuit; /// Build a tiny circuit: H(0) CX(0,1) H(0) MZ(0) MZ(1) @@ -452,22 +452,30 @@ mod tests { p_prep: 0.0, }; let catalog = build_fault_catalog(&tc, &noise).unwrap(); - assert!(catalog - .locations - .iter() - .any(|loc| loc.gate_type == GateType::SX)); - assert!(catalog - .locations - .iter() - .any(|loc| loc.gate_type == GateType::CY)); - assert!(catalog - .locations - .iter() - .any(|loc| loc.gate_type == GateType::SXX)); - assert!(catalog - .locations - .iter() - .any(|loc| loc.gate_type == GateType::SWAP)); + assert!( + catalog + .locations + .iter() + .any(|loc| loc.gate_type == GateType::SX) + ); + assert!( + catalog + .locations + .iter() + .any(|loc| loc.gate_type == GateType::CY) + ); + assert!( + catalog + .locations + .iter() + .any(|loc| loc.gate_type == GateType::SXX) + ); + assert!( + catalog + .locations + .iter() + .any(|loc| loc.gate_type == GateType::SWAP) + ); let decoder = TargetedLookupDecoder::new(&catalog).max_faults(2); let bf = brute_force_weights(&catalog, 2); diff --git a/python/pecos-rslib/src/fault_tolerance_bindings.rs b/python/pecos-rslib/src/fault_tolerance_bindings.rs index 446479fe7..a017967b3 100644 --- a/python/pecos-rslib/src/fault_tolerance_bindings.rs +++ b/python/pecos-rslib/src/fault_tolerance_bindings.rs @@ -689,11 +689,11 @@ impl PyInfluenceBuilder { // Detector Error Model // ============================================================================= -/// A Detector Error Model (DEM) in Stim-compatible format. +/// A Detector Error Model (DEM) in standard DEM text format. /// /// This represents the error model of a quantum circuit, mapping error -/// mechanisms to their probabilities. It can be converted to Stim format -/// for use with Stim-based decoders. +/// mechanisms to their probabilities. It can be exported as DEM text for use +/// with compatible decoders. /// /// # Example /// @@ -991,8 +991,7 @@ impl PyDetectorErrorModel { /// Convert the DEM to a string in standard DEM format. /// /// Each error mechanism is output with its total probability, with no - /// splitting into decomposed forms. This matches Stim's - /// `detector_error_model(decompose_errors=False)` output. + /// splitting into decomposed forms. /// /// Returns: /// A string in DEM format with one entry per mechanism. @@ -1007,8 +1006,6 @@ impl PyDetectorErrorModel { /// including L0 cancellation forms where available. Hyperedge errors /// (affecting 3+ detectors) are decomposed into graphlike components. /// - /// This matches Stim's `detector_error_model(decompose_errors=True)` output. - /// /// Returns: /// A string in DEM format with decomposed representations. fn to_string_decomposed(&self) -> String { @@ -2704,7 +2701,7 @@ impl PySampleBatch { /// This runs entirely in Rust -- no per-shot Python crossing. /// /// Args: - /// dem: DEM string (Stim format) for the decoder. + /// dem: DEM string in standard DEM text format for the decoder. /// `decoder_type`: "pymatching", "tesseract", "`bp_osd`", "`bp_lsd`", "`union_find`", /// "`relay_bp`", or "`min_sum_bp`". /// @@ -3130,7 +3127,7 @@ impl PyDemSampler { } } - /// Create a sampler from a Stim-format DEM string. + /// Create a sampler from a standard DEM-format string. /// /// Parses `error(p) D0 D3 L0` lines and builds a sampling engine. /// Useful for sampling from DEMs produced by EEG analysis. @@ -3416,8 +3413,8 @@ impl PyDemSampler { let actual_seed = seed.unwrap_or_else(|| rand::rng().random()); let stats = self.inner.sample_statistics(num_shots, actual_seed); - let observable_indices = self.inner.observable_dem_output_indices(); - let tracked_op_indices = self.inner.tracked_operator_dem_output_indices(); + let observable_indices = self.inner.observable_ids(); + let tracked_op_indices = self.inner.tracked_operator_ids(); let per_observable = stats.observable_counts(&observable_indices); let per_tracked_op: Vec = tracked_op_indices .iter() @@ -3476,7 +3473,7 @@ impl PyDemSampler { /// are counted, all in Rust. /// /// Args: - /// dem: DEM string (Stim format) for the decoder. + /// dem: DEM string in standard DEM text format for the decoder. /// `num_shots`: Number of shots to sample and decode. /// `decoder_type`: "pymatching" or "tesseract". /// seed: Optional random seed for reproducibility. @@ -3521,7 +3518,7 @@ impl PyDemSampler { /// Much faster for slow decoders (Tesseract) where decode time dominates. /// /// Args: - /// dem: DEM string (Stim format) for the decoder. + /// dem: DEM string in standard DEM text format for the decoder. /// `num_shots`: Number of shots to sample and decode. /// `decoder_type`: "pymatching", "tesseract", "`bp_osd`", "`bp_lsd`", or "`union_find`". /// seed: Optional base random seed. Each thread gets seed + `thread_id`. @@ -3853,7 +3850,7 @@ impl PyEquivalenceResult { /// A parsed Detector Error Model. /// -/// Parses DEM strings in Stim/PECOS format and provides methods for +/// Parses standard and PECOS DEM strings and provides methods for /// aggregation and sampling. /// /// # Example @@ -3875,7 +3872,7 @@ impl PyParsedDem { /// Parse a DEM from a string. /// /// Args: - /// `dem_str`: DEM string in Stim/PECOS format. + /// `dem_str`: DEM string in standard or PECOS DEM text format. /// /// Returns: /// `ParsedDem` object. @@ -4321,7 +4318,7 @@ impl PyCssUfDecoder { /// stabilizer coordinate information, then decodes each independently. /// /// Args: -/// dem: DEM string in Stim format with detector coordinate declarations. +/// dem: DEM string with detector coordinate declarations. /// `stab_coords`: List of dicts, one per logical qubit. Each dict has /// keys "X" and "Z" mapping to lists of (x, y) ancilla coordinates. /// `inner_decoder`: Inner decoder type string (default "`pecos_uf:fast`"). @@ -5460,7 +5457,7 @@ fn fit_dem_to_marginals( (result, residuals) } -/// Format DEM mechanisms as a Stim DEM string. +/// Format DEM mechanisms as a standard DEM string. #[pyfunction] fn mechanisms_to_dem_string(mechanisms: Vec<(f64, Vec, Vec)>) -> String { use pecos_qec::fault_tolerance::correlation::{ From 16a9a9cb2dc111ce11ec646ddd1a125f11456967 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Fri, 8 May 2026 16:17:35 -0600 Subject: [PATCH 054/125] Clippy cleanup, lint tightening, terminology fixes --- crates/pecos-core/src/lib.rs | 4 +- crates/pecos-core/src/meas_id.rs | 4 +- crates/pecos-core/src/pauli/pauli_bitmask.rs | 550 ++++++-- crates/pecos-decoder-core/src/adaptive.rs | 14 +- crates/pecos-decoder-core/src/bp_matching.rs | 38 +- .../src/correlated_reweighting.rs | 12 +- .../src/correlation_table.rs | 11 +- .../pecos-decoder-core/src/ghost_protocol.rs | 20 +- crates/pecos-decoder-core/src/k_mwpm.rs | 9 +- crates/pecos-decoder-core/src/lib.rs | 11 + .../src/observable_subgraph.rs | 32 +- crates/pecos-decoder-core/src/perturbed.rs | 33 +- crates/pecos-decoder-core/src/windowed_osd.rs | 10 +- .../pecos-fusion-blossom/src/core_traits.rs | 6 +- crates/pecos-fusion-blossom/src/decoder.rs | 37 +- crates/pecos-mwpf/src/decoder.rs | 14 +- crates/pecos-phir-json/src/v0_1/ast.rs | 6 +- .../src/fault_tolerance/correlation.rs | 80 +- .../fault_tolerance/dem_builder/builder.rs | 2 + .../dem_builder/dem_sampler.rs | 29 +- .../dem_builder/equivalence.rs | 2 +- .../fault_tolerance/dem_builder/sampler.rs | 68 +- .../src/fault_tolerance/dem_builder/types.rs | 58 +- .../src/fault_tolerance/fault_sampler.rs | 197 +-- .../src/fault_tolerance/influence_builder.rs | 101 +- .../src/fault_tolerance/propagator/dag.rs | 111 +- .../targeted_lookup_decoder.rs | 109 +- .../tests/fault_enumeration_example.rs | 4 +- crates/pecos-quantum/src/pass.rs | 10 +- crates/pecos-quantum/src/tick_circuit.rs | 10 +- crates/pecos-simulators/src/pauli_prop.rs | 12 +- crates/pecos-simulators/src/state_vec_soa.rs | 6 +- .../src/state_vector_test_utils.rs | 6 +- .../src/symbolic_sparse_stab.rs | 4 +- .../examples/profile_decode.rs | 18 +- crates/pecos-uf-decoder/src/bp_uf.rs | 26 +- crates/pecos-uf-decoder/src/decoder.rs | 24 +- crates/pecos-uf-decoder/src/mini_bp.rs | 46 +- crates/pecos-uf-decoder/src/windowed.rs | 46 +- exp/pecos-eeg/examples/profile_heisenberg.rs | 35 +- exp/pecos-eeg/src/builder.rs | 109 +- exp/pecos-eeg/src/circuit.rs | 313 +++-- exp/pecos-eeg/src/coherent_dem.rs | 240 +++- exp/pecos-eeg/src/correlation_table.rs | 55 +- exp/pecos-eeg/src/dem_generator.rs | 32 +- exp/pecos-eeg/src/dem_mapping.rs | 716 +++++++--- exp/pecos-eeg/src/dem_simulator.rs | 31 +- exp/pecos-eeg/src/expand.rs | 86 +- exp/pecos-eeg/src/heisenberg.rs | 1235 +++++++++++------ exp/pecos-eeg/src/lib.rs | 17 +- exp/pecos-eeg/src/noise.rs | 119 +- exp/pecos-eeg/src/noise_characterization.rs | 171 ++- exp/pecos-eeg/src/noise_compression.rs | 81 +- exp/pecos-eeg/src/stabilizer.rs | 125 +- exp/pecos-eeg/src/strong_sim.rs | 161 ++- exp/pecos-eeg/tests/beta_investigation.rs | 64 +- exp/pecos-eeg/tests/generator_trace.rs | 223 ++- exp/pecos-eeg/tests/stabilizer_audit.rs | 165 ++- exp/pecos-eeg/tests/statevec_comparison.rs | 608 +++++--- exp/pecos-eeg/tests/strong_sim_validation.rs | 103 +- exp/pecos-eeg/tests/surface_code.rs | 37 +- exp/pecos-neo/src/command/builder.rs | 6 +- exp/pecos-neo/src/tool.rs | 4 +- exp/pecos-neo/src/tool/simulation.rs | 3 - python/pecos-rslib-exp/src/eeg_bindings.rs | 218 +-- python/pecos-rslib-exp/src/lib.rs | 14 + .../pecos-rslib-exp/src/sim_neo_bindings.rs | 118 +- .../src/fault_tolerance_bindings.rs | 174 +-- python/pecos-rslib/src/lib.rs | 14 +- .../tests/qec/test_fault_catalog.py | 2 +- 70 files changed, 4571 insertions(+), 2488 deletions(-) diff --git a/crates/pecos-core/src/lib.rs b/crates/pecos-core/src/lib.rs index 6a93a8eb9..59a86996c 100644 --- a/crates/pecos-core/src/lib.rs +++ b/crates/pecos-core/src/lib.rs @@ -27,10 +27,10 @@ pub mod gate_registry; pub mod gate_type; pub mod gates; pub mod index_set; +pub mod meas_id; pub mod pauli; pub mod phase; pub mod prelude; -pub mod meas_id; pub mod qubit_id; pub mod rng; pub mod sets; @@ -47,10 +47,10 @@ pub use bitset::BitSet; pub use duration::{TimeScale, TimeUnits}; pub use element::Element; pub use index_set::IndexSet; +pub use meas_id::MeasId; pub use phase::GlobalPhase; pub use phase::quarter_phase::QuarterPhase; pub use phase::sign::Sign; -pub use meas_id::MeasId; pub use qubit_id::{QubitId, QubitIdSet, qid, qid2, qids, qids2}; pub use rng::{RngManageable, derive_seed}; pub use sets::set::Set; diff --git a/crates/pecos-core/src/meas_id.rs b/crates/pecos-core/src/meas_id.rs index e3ab6ea03..4a6f71fb0 100644 --- a/crates/pecos-core/src/meas_id.rs +++ b/crates/pecos-core/src/meas_id.rs @@ -6,8 +6,8 @@ //! //! Each measurement gate (MZ, MX, etc.) produces a `MeasId` — a unique //! identifier for that measurement's outcome. Assigned once at circuit -//! construction time, carried through all transformations (TickCircuit → -//! DagCircuit → InfluenceMap → DEM). Never reassigned. +//! construction time, carried through all transformations (`TickCircuit` → +//! `DagCircuit` → `InfluenceMap` → DEM). Never reassigned. //! //! This follows the MLIR SSA pattern: the value is defined at one point //! and referenced everywhere. Detectors reference `MeasId` values diff --git a/crates/pecos-core/src/pauli/pauli_bitmask.rs b/crates/pecos-core/src/pauli/pauli_bitmask.rs index 2446bb280..b274b83e0 100644 --- a/crates/pecos-core/src/pauli/pauli_bitmask.rs +++ b/crates/pecos-core/src/pauli/pauli_bitmask.rs @@ -17,9 +17,7 @@ use std::fmt; /// /// Enables `PauliBitmaskGeneric` to work with different widths: /// `u64` (64 qubits), `u128` (128 qubits), or `Vec` (unlimited). -pub trait BitmaskStorage: - Clone + PartialEq + Eq + std::hash::Hash + Default + fmt::Debug -{ +pub trait BitmaskStorage: Clone + PartialEq + Eq + std::hash::Hash + Default + fmt::Debug { fn zero() -> Self; fn set_bit(&mut self, bit: usize); fn clear_bit(&mut self, bit: usize); @@ -33,48 +31,84 @@ pub trait BitmaskStorage: } impl BitmaskStorage for u128 { - fn zero() -> Self { 0 } - fn set_bit(&mut self, bit: usize) { *self |= 1u128 << bit; } - fn clear_bit(&mut self, bit: usize) { *self &= !(1u128 << bit); } - fn get_bit(&self, bit: usize) -> bool { *self & (1u128 << bit) != 0 } - fn xor_assign(&mut self, other: &Self) { *self ^= other; } - fn xor_bit(&mut self, bit: usize) { *self ^= 1u128 << bit; } + fn zero() -> Self { + 0 + } + fn set_bit(&mut self, bit: usize) { + *self |= 1u128 << bit; + } + fn clear_bit(&mut self, bit: usize) { + *self &= !(1u128 << bit); + } + fn get_bit(&self, bit: usize) -> bool { + *self & (1u128 << bit) != 0 + } + fn xor_assign(&mut self, other: &Self) { + *self ^= other; + } + fn xor_bit(&mut self, bit: usize) { + *self ^= 1u128 << bit; + } fn and_count_ones_xor(&self, other_z: &Self, self_z: &Self, other_x: &Self) -> u32 { ((*self & other_z) ^ (self_z & other_x)).count_ones() } - fn is_zero(&self) -> bool { *self == 0 } - fn or_count_ones(&self, other: &Self) -> u32 { (*self | other).count_ones() } + fn is_zero(&self) -> bool { + *self == 0 + } + fn or_count_ones(&self, other: &Self) -> u32 { + (*self | other).count_ones() + } fn highest_set_bit(&self) -> Option { - if *self == 0 { None } else { Some(127 - self.leading_zeros() as usize) } + if *self == 0 { + None + } else { + Some(127 - self.leading_zeros() as usize) + } } } impl BitmaskStorage for Vec { - fn zero() -> Self { Vec::new() } + fn zero() -> Self { + Vec::new() + } fn set_bit(&mut self, bit: usize) { let word = bit / 64; - if word >= self.len() { self.resize(word + 1, 0); } + if word >= self.len() { + self.resize(word + 1, 0); + } self[word] |= 1u64 << (bit % 64); } fn clear_bit(&mut self, bit: usize) { let word = bit / 64; - if word < self.len() { self[word] &= !(1u64 << (bit % 64)); } + if word < self.len() { + self[word] &= !(1u64 << (bit % 64)); + } } fn get_bit(&self, bit: usize) -> bool { let word = bit / 64; word < self.len() && self[word] & (1u64 << (bit % 64)) != 0 } fn xor_assign(&mut self, other: &Self) { - if self.len() < other.len() { self.resize(other.len(), 0); } - for (a, b) in self.iter_mut().zip(other.iter()) { *a ^= b; } + if self.len() < other.len() { + self.resize(other.len(), 0); + } + for (a, b) in self.iter_mut().zip(other.iter()) { + *a ^= b; + } } fn xor_bit(&mut self, bit: usize) { let word = bit / 64; - if word >= self.len() { self.resize(word + 1, 0); } + if word >= self.len() { + self.resize(word + 1, 0); + } self[word] ^= 1u64 << (bit % 64); } fn and_count_ones_xor(&self, other_z: &Self, self_z: &Self, other_x: &Self) -> u32 { - let max = self.len().max(other_z.len()).max(self_z.len()).max(other_x.len()); + let max = self + .len() + .max(other_z.len()) + .max(self_z.len()) + .max(other_x.len()); let mut count = 0u32; for i in 0..max { let sx = self.get(i).copied().unwrap_or(0); @@ -85,7 +119,9 @@ impl BitmaskStorage for Vec { } count } - fn is_zero(&self) -> bool { self.iter().all(|&w| w == 0) } + fn is_zero(&self) -> bool { + self.iter().all(|&w| w == 0) + } fn or_count_ones(&self, other: &Self) -> u32 { let max = self.len().max(other.len()); let mut count = 0u32; @@ -98,40 +134,58 @@ impl BitmaskStorage for Vec { } fn highest_set_bit(&self) -> Option { for (i, &w) in self.iter().enumerate().rev() { - if w != 0 { return Some(i * 64 + 63 - w.leading_zeros() as usize); } + if w != 0 { + return Some(i * 64 + 63 - w.leading_zeros() as usize); + } } None } } -/// SmallVec<[u64; 8]> backend: 512 bits inline (covers d≤9 surface codes), +/// `SmallVec<[u64; 8]>` backend: 512 bits inline (covers d≤9 surface codes), /// spills to heap for larger circuits. Zero allocation for typical QEC. impl BitmaskStorage for SmallVec<[u64; 8]> { - fn zero() -> Self { SmallVec::new() } + fn zero() -> Self { + SmallVec::new() + } fn set_bit(&mut self, bit: usize) { let word = bit / 64; - if word >= self.len() { self.resize(word + 1, 0); } + if word >= self.len() { + self.resize(word + 1, 0); + } self[word] |= 1u64 << (bit % 64); } fn clear_bit(&mut self, bit: usize) { let word = bit / 64; - if word < self.len() { self[word] &= !(1u64 << (bit % 64)); } + if word < self.len() { + self[word] &= !(1u64 << (bit % 64)); + } } fn get_bit(&self, bit: usize) -> bool { let word = bit / 64; word < self.len() && self[word] & (1u64 << (bit % 64)) != 0 } fn xor_assign(&mut self, other: &Self) { - if self.len() < other.len() { self.resize(other.len(), 0); } - for (a, b) in self.iter_mut().zip(other.iter()) { *a ^= b; } + if self.len() < other.len() { + self.resize(other.len(), 0); + } + for (a, b) in self.iter_mut().zip(other.iter()) { + *a ^= b; + } } fn xor_bit(&mut self, bit: usize) { let word = bit / 64; - if word >= self.len() { self.resize(word + 1, 0); } + if word >= self.len() { + self.resize(word + 1, 0); + } self[word] ^= 1u64 << (bit % 64); } fn and_count_ones_xor(&self, other_z: &Self, self_z: &Self, other_x: &Self) -> u32 { - let max = self.len().max(other_z.len()).max(self_z.len()).max(other_x.len()); + let max = self + .len() + .max(other_z.len()) + .max(self_z.len()) + .max(other_x.len()); let mut count = 0u32; for i in 0..max { let sx = self.get(i).copied().unwrap_or(0); @@ -142,7 +196,9 @@ impl BitmaskStorage for SmallVec<[u64; 8]> { } count } - fn is_zero(&self) -> bool { self.iter().all(|&w| w == 0) } + fn is_zero(&self) -> bool { + self.iter().all(|&w| w == 0) + } fn or_count_ones(&self, other: &Self) -> u32 { let max = self.len().max(other.len()); let mut count = 0u32; @@ -155,7 +211,9 @@ impl BitmaskStorage for SmallVec<[u64; 8]> { } fn highest_set_bit(&self) -> Option { for (i, &w) in self.iter().enumerate().rev() { - if w != 0 { return Some(i * 64 + 63 - w.leading_zeros() as usize); } + if w != 0 { + return Some(i * 64 + 63 - w.leading_zeros() as usize); + } } None } @@ -263,13 +321,19 @@ impl std::hash::Hash for PauliBitmaskSmall { } impl PartialOrd for PauliBitmaskSmall { - fn partial_cmp(&self, other: &Self) -> Option { Some(self.cmp(other)) } + fn partial_cmp(&self, other: &Self) -> Option { + Some(self.cmp(other)) + } } impl Ord for PauliBitmaskSmall { fn cmp(&self, other: &Self) -> std::cmp::Ordering { - let max_len = self.x_bits.len().max(other.x_bits.len()) - .max(self.z_bits.len()).max(other.z_bits.len()); + let max_len = self + .x_bits + .len() + .max(other.x_bits.len()) + .max(self.z_bits.len()) + .max(other.z_bits.len()); for i in (0..max_len).rev() { let sx = self.x_bits.get(i).copied().unwrap_or(0); let ox = other.x_bits.get(i).copied().unwrap_or(0); @@ -293,22 +357,32 @@ impl Ord for PauliBitmaskSmall { // Copy only for fixed-size backends impl Copy for PauliBitmask {} impl PartialOrd for PauliBitmask { - fn partial_cmp(&self, other: &Self) -> Option { Some(self.cmp(other)) } + fn partial_cmp(&self, other: &Self) -> Option { + Some(self.cmp(other)) + } } impl Ord for PauliBitmask { fn cmp(&self, other: &Self) -> std::cmp::Ordering { - self.x_bits.cmp(&other.x_bits).then(self.z_bits.cmp(&other.z_bits)) + self.x_bits + .cmp(&other.x_bits) + .then(self.z_bits.cmp(&other.z_bits)) } } impl PartialOrd for PauliBitmaskVec { - fn partial_cmp(&self, other: &Self) -> Option { Some(self.cmp(other)) } + fn partial_cmp(&self, other: &Self) -> Option { + Some(self.cmp(other)) + } } impl Ord for PauliBitmaskVec { fn cmp(&self, other: &Self) -> std::cmp::Ordering { // Lexicographic comparison of the word vectors (most-significant word first) - let max_len = self.x_bits.len().max(other.x_bits.len()) - .max(self.z_bits.len()).max(other.z_bits.len()); + let max_len = self + .x_bits + .len() + .max(other.x_bits.len()) + .max(self.z_bits.len()) + .max(other.z_bits.len()); for i in (0..max_len).rev() { let sx = self.x_bits.get(i).copied().unwrap_or(0); let ox = other.x_bits.get(i).copied().unwrap_or(0); @@ -335,7 +409,10 @@ impl PauliBitmaskGeneric { pub fn x(q: usize) -> Self { let mut x = B::zero(); x.set_bit(q); - Self { x_bits: x, z_bits: B::zero() } + Self { + x_bits: x, + z_bits: B::zero(), + } } /// Single-qubit Z on qubit q. @@ -343,7 +420,10 @@ impl PauliBitmaskGeneric { pub fn z(q: usize) -> Self { let mut z = B::zero(); z.set_bit(q); - Self { x_bits: B::zero(), z_bits: z } + Self { + x_bits: B::zero(), + z_bits: z, + } } /// Single-qubit Y on qubit q. @@ -353,7 +433,10 @@ impl PauliBitmaskGeneric { let mut z = B::zero(); x.set_bit(q); z.set_bit(q); - Self { x_bits: x, z_bits: z } + Self { + x_bits: x, + z_bits: z, + } } /// Product of two Pauli labels (XOR of symplectic vectors, phase ignored). @@ -363,17 +446,18 @@ impl PauliBitmaskGeneric { x.xor_assign(&other.x_bits); let mut z = self.z_bits.clone(); z.xor_assign(&other.z_bits); - Self { x_bits: x, z_bits: z } + Self { + x_bits: x, + z_bits: z, + } } /// Product of two Paulis with phase tracking. /// - /// Returns (product, phase_exponent) where the full product is i^phase · product. + /// Returns `(product, phase_exponent)` where the full product is i^phase · product. /// Phase exponent is in 0..4. #[must_use] pub fn multiply_with_phase(&self, other: &Self) -> (Self, u8) { - let product = self.multiply(other); - // Per-qubit phase from Pauli multiplication. // Pauli types: I=0, X=1, Z=2, Y=3 (encoding: type = x + 2*z) // Phase lookup: A*B = i^{phase[A][B]} * C @@ -389,37 +473,24 @@ impl PauliBitmaskGeneric { [0, 3, 1, 0], // Y ]; + let product = self.multiply(other); let mut total_phase = 0u32; - let max_q = match self.x_bits.highest_set_bit() { - Some(a) => { - let b = other.x_bits.highest_set_bit().unwrap_or(0); - let c = self.z_bits.highest_set_bit().unwrap_or(0); - let d = other.z_bits.highest_set_bit().unwrap_or(0); - a.max(b).max(c).max(d) + 1 - } - None => match other.x_bits.highest_set_bit() { - Some(b) => { - let c = self.z_bits.highest_set_bit().unwrap_or(0); - let d = other.z_bits.highest_set_bit().unwrap_or(0); - b.max(c).max(d) + 1 - } - None => { - let c = self.z_bits.highest_set_bit().unwrap_or(0); - let d = other.z_bits.highest_set_bit().unwrap_or(0); - if c == 0 && d == 0 && self.z_bits.is_zero() && other.z_bits.is_zero() { - 0 - } else { - c.max(d) + 1 - } - } - }, - }; + let max_q = [ + self.x_bits.highest_set_bit(), + other.x_bits.highest_set_bit(), + self.z_bits.highest_set_bit(), + other.z_bits.highest_set_bit(), + ] + .into_iter() + .flatten() + .max() + .map_or(0, |q| q + 1); for q in 0..max_q { - let xa = self.x_bits.get_bit(q) as usize; - let za = self.z_bits.get_bit(q) as usize; - let xb = other.x_bits.get_bit(q) as usize; - let zb = other.z_bits.get_bit(q) as usize; + let xa = usize::from(self.x_bits.get_bit(q)); + let za = usize::from(self.z_bits.get_bit(q)); + let xb = usize::from(other.x_bits.get_bit(q)); + let zb = usize::from(other.z_bits.get_bit(q)); let type_a = xa + 2 * za; // I=0, X=1, Z=2, Y=3 let type_b = xb + 2 * zb; total_phase += u32::from(PHASE_TABLE[type_a][type_b]); @@ -433,8 +504,7 @@ impl PauliBitmaskGeneric { pub fn commutes_with(&self, other: &Self) -> bool { self.x_bits .and_count_ones_xor(&other.z_bits, &self.z_bits, &other.x_bits) - % 2 - == 0 + .is_multiple_of(2) } #[must_use] @@ -460,44 +530,73 @@ impl PauliBitmaskGeneric { } impl PauliBitmask { - pub const IDENTITY: Self = Self { x_bits: 0, z_bits: 0 }; + pub const IDENTITY: Self = Self { + x_bits: 0, + z_bits: 0, + }; } impl PauliBitmaskGeneric { /// Identity Pauli (all qubits I). #[must_use] pub fn identity() -> Self { - Self { x_bits: B::zero(), z_bits: B::zero() } + Self { + x_bits: B::zero(), + z_bits: B::zero(), + } } } /// Convert from u128 (fixed-size) to Vec (unlimited) backend. impl From for PauliBitmaskVec { fn from(p: PauliBitmask) -> Self { - let x_lo = p.x_bits as u64; - let x_hi = (p.x_bits >> 64) as u64; - let z_lo = p.z_bits as u64; - let z_hi = (p.z_bits >> 64) as u64; + let x_lo = u64::try_from(p.x_bits & u128::from(u64::MAX)).expect("masked low word fits"); + let x_hi = u64::try_from(p.x_bits >> 64).expect("shifted high word fits"); + let z_lo = u64::try_from(p.z_bits & u128::from(u64::MAX)).expect("masked low word fits"); + let z_hi = u64::try_from(p.z_bits >> 64).expect("shifted high word fits"); Self { - x_bits: if x_hi != 0 { vec![x_lo, x_hi] } else if x_lo != 0 { vec![x_lo] } else { vec![] }, - z_bits: if z_hi != 0 { vec![z_lo, z_hi] } else if z_lo != 0 { vec![z_lo] } else { vec![] }, + x_bits: if x_hi != 0 { + vec![x_lo, x_hi] + } else if x_lo != 0 { + vec![x_lo] + } else { + vec![] + }, + z_bits: if z_hi != 0 { + vec![z_lo, z_hi] + } else if z_lo != 0 { + vec![z_lo] + } else { + vec![] + }, } } } impl From for PauliBitmaskSmall { fn from(p: PauliBitmask) -> Self { - let x_lo = p.x_bits as u64; - let x_hi = (p.x_bits >> 64) as u64; - let z_lo = p.z_bits as u64; - let z_hi = (p.z_bits >> 64) as u64; + let x_lo = u64::try_from(p.x_bits & u128::from(u64::MAX)).expect("masked low word fits"); + let x_hi = u64::try_from(p.x_bits >> 64).expect("shifted high word fits"); + let z_lo = u64::try_from(p.z_bits & u128::from(u64::MAX)).expect("masked low word fits"); + let z_hi = u64::try_from(p.z_bits >> 64).expect("shifted high word fits"); let mut x = SmallVec::new(); - if x_hi != 0 { x.push(x_lo); x.push(x_hi); } - else if x_lo != 0 { x.push(x_lo); } + if x_hi != 0 { + x.push(x_lo); + x.push(x_hi); + } else if x_lo != 0 { + x.push(x_lo); + } let mut z = SmallVec::new(); - if z_hi != 0 { z.push(z_lo); z.push(z_hi); } - else if z_lo != 0 { z.push(z_lo); } - Self { x_bits: x, z_bits: z } + if z_hi != 0 { + z.push(z_lo); + z.push(z_hi); + } else if z_lo != 0 { + z.push(z_lo); + } + Self { + x_bits: x, + z_bits: z, + } } } @@ -552,31 +651,46 @@ pub fn conjugate_h(p: &PauliBitmaskGeneric, q: usize) -> C label.x_bits.xor_bit(q); label.z_bits.xor_bit(q); } - Conjugated { label, sign_negative: has_x && has_z } + Conjugated { + label, + sign_negative: has_x && has_z, + } } /// SZ gate on qubit q: X→Y, Y→-X, Z→Z. #[must_use] pub fn conjugate_sz(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { if !p.x_bits.get_bit(q) { - return Conjugated { label: p.clone(), sign_negative: false }; + return Conjugated { + label: p.clone(), + sign_negative: false, + }; } let was_y = p.z_bits.get_bit(q); let mut label = p.clone(); label.z_bits.xor_bit(q); - Conjugated { label, sign_negative: was_y } + Conjugated { + label, + sign_negative: was_y, + } } -/// SZdg gate on qubit q: X→-Y, Y→X, Z→Z. +/// `SZdg` gate on qubit q: X→-Y, Y→X, Z→Z. #[must_use] pub fn conjugate_szdg(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { if !p.x_bits.get_bit(q) { - return Conjugated { label: p.clone(), sign_negative: false }; + return Conjugated { + label: p.clone(), + sign_negative: false, + }; } let was_y = p.z_bits.get_bit(q); let mut label = p.clone(); label.z_bits.xor_bit(q); - Conjugated { label, sign_negative: !was_y } + Conjugated { + label, + sign_negative: !was_y, + } } /// CX (CNOT) with control c, target t: XI→XX, IZ→ZZ. @@ -584,51 +698,77 @@ pub fn conjugate_szdg(p: &PauliBitmaskGeneric, q: usize) - /// The sign comes from Pauli multiplication phases when the control's /// Pauli multiplies Z (from target Z spreading) and the target's Pauli /// multiplies X (from control X spreading): -/// phase_c = phase(Pc · Z) if target has Z, else 0 -/// phase_t = phase(X · Pt) if control has X, else 0 -/// sign_negative = (phase_c + phase_t) % 4 == 2 +/// `phase_c` = phase(Pc · Z) if target has Z, else 0 +/// `phase_t` = phase(X · Pt) if control has X, else 0 +/// `sign_negative` = (`phase_c` + `phase_t`) % 4 == 2 #[must_use] -pub fn conjugate_cx(p: &PauliBitmaskGeneric, c: usize, t: usize) -> Conjugated { +pub fn conjugate_cx( + p: &PauliBitmaskGeneric, + c: usize, + t: usize, +) -> Conjugated { + const PHASE: [[u8; 4]; 4] = [ + [0, 0, 0, 0], // I·{I,X,Z,Y} + [0, 0, 3, 1], // X·{I,X,Z,Y} + [0, 1, 0, 3], // Z·{I,X,Z,Y} + [0, 3, 1, 0], // Y·{I,X,Z,Y} + ]; + let cx = p.x_bits.get_bit(c); let cz = p.z_bits.get_bit(c); let tx = p.x_bits.get_bit(t); let tz = p.z_bits.get_bit(t); let mut label = p.clone(); - if cx { label.x_bits.xor_bit(t); } - if tz { label.z_bits.xor_bit(c); } + if cx { + label.x_bits.xor_bit(t); + } + if tz { + label.z_bits.xor_bit(c); + } // Pauli type encoding: I=0, X=1, Z=2, Y=3 (x + 2*z) // Phase from Pauli multiplication table: // Pc·Z at control (if tz), X·Pt at target (if cx) - const PHASE: [[u8; 4]; 4] = [ - [0, 0, 0, 0], // I·{I,X,Z,Y} - [0, 0, 3, 1], // X·{I,X,Z,Y} - [0, 1, 0, 3], // Z·{I,X,Z,Y} - [0, 3, 1, 0], // Y·{I,X,Z,Y} - ]; - let pc = (cx as u8) + 2 * (cz as u8); - let pt = (tx as u8) + 2 * (tz as u8); + let pc = u8::from(cx) + 2 * u8::from(cz); + let pt = u8::from(tx) + 2 * u8::from(tz); let phase_c = if tz { PHASE[pc as usize][2] } else { 0 }; let phase_t = if cx { PHASE[1][pt as usize] } else { 0 }; - Conjugated { label, sign_negative: (phase_c + phase_t) % 4 == 2 } + Conjugated { + label, + sign_negative: (phase_c + phase_t) % 4 == 2, + } } /// CZ on qubits a, b: XI→XZ, IX→ZX, ZI→ZI, IZ→IZ. #[must_use] -pub fn conjugate_cz(p: &PauliBitmaskGeneric, a: usize, b: usize) -> Conjugated { +pub fn conjugate_cz( + p: &PauliBitmaskGeneric, + a: usize, + b: usize, +) -> Conjugated { let ax = p.x_bits.get_bit(a); let az = p.z_bits.get_bit(a); let bx = p.x_bits.get_bit(b); let bz = p.z_bits.get_bit(b); let mut label = p.clone(); - if bx { label.z_bits.xor_bit(a); } - if ax { label.z_bits.xor_bit(b); } - Conjugated { label, sign_negative: ax && bx && (az != bz) } + if bx { + label.z_bits.xor_bit(a); + } + if ax { + label.z_bits.xor_bit(b); + } + Conjugated { + label, + sign_negative: ax && bx && (az != bz), + } } /// Pauli X gate on qubit q: Z→-Z, Y→-Y. #[must_use] pub fn conjugate_x(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { - Conjugated { label: p.clone(), sign_negative: p.z_bits.get_bit(q) } + Conjugated { + label: p.clone(), + sign_negative: p.z_bits.get_bit(q), + } } /// Pauli Y gate on qubit q: X→-X, Z→-Z. @@ -643,28 +783,50 @@ pub fn conjugate_y(p: &PauliBitmaskGeneric, q: usize) -> C /// Pauli Z gate on qubit q: X→-X, Y→-Y. #[must_use] pub fn conjugate_z(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { - Conjugated { label: p.clone(), sign_negative: p.x_bits.get_bit(q) } + Conjugated { + label: p.clone(), + sign_negative: p.x_bits.get_bit(q), + } } /// SWAP on qubits a, b: exchanges the Pauli at both sites. #[must_use] -pub fn conjugate_swap(p: &PauliBitmaskGeneric, a: usize, b: usize) -> Conjugated { +pub fn conjugate_swap( + p: &PauliBitmaskGeneric, + a: usize, + b: usize, +) -> Conjugated { let ax = p.x_bits.get_bit(a); let az = p.z_bits.get_bit(a); let bx = p.x_bits.get_bit(b); let bz = p.z_bits.get_bit(b); let mut label = p.clone(); // Clear both positions - if ax { label.x_bits.clear_bit(a); } else { label.x_bits.clear_bit(a); } - if bx { label.x_bits.clear_bit(b); } else { label.x_bits.clear_bit(b); } - if az { label.z_bits.clear_bit(a); } - if bz { label.z_bits.clear_bit(b); } + label.x_bits.clear_bit(a); + label.x_bits.clear_bit(b); + if az { + label.z_bits.clear_bit(a); + } + if bz { + label.z_bits.clear_bit(b); + } // Set swapped - if bx { label.x_bits.set_bit(a); } - if ax { label.x_bits.set_bit(b); } - if bz { label.z_bits.set_bit(a); } - if az { label.z_bits.set_bit(b); } - Conjugated { label, sign_negative: false } + if bx { + label.x_bits.set_bit(a); + } + if ax { + label.x_bits.set_bit(b); + } + if bz { + label.z_bits.set_bit(a); + } + if az { + label.z_bits.set_bit(b); + } + Conjugated { + label, + sign_negative: false, + } } /// SX gate on qubit q: X→X, Z→-Y, Y→Z. @@ -673,18 +835,28 @@ pub fn conjugate_sx(p: &PauliBitmaskGeneric, q: usize) -> let xq = p.x_bits.get_bit(q); let zq = p.z_bits.get_bit(q); let mut label = p.clone(); - if zq { label.x_bits.xor_bit(q); } - Conjugated { label, sign_negative: !xq && zq } + if zq { + label.x_bits.xor_bit(q); + } + Conjugated { + label, + sign_negative: !xq && zq, + } } -/// SXdg gate on qubit q: X→X, Z→Y, Y→-Z. +/// `SXdg` gate on qubit q: X→X, Z→Y, Y→-Z. #[must_use] pub fn conjugate_sxdg(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { let xq = p.x_bits.get_bit(q); let zq = p.z_bits.get_bit(q); let mut label = p.clone(); - if zq { label.x_bits.xor_bit(q); } - Conjugated { label, sign_negative: xq && zq } + if zq { + label.x_bits.xor_bit(q); + } + Conjugated { + label, + sign_negative: xq && zq, + } } /// SY gate on qubit q: X→-Z, Y→Y, Z→X. @@ -697,10 +869,13 @@ pub fn conjugate_sy(p: &PauliBitmaskGeneric, q: usize) -> label.x_bits.xor_bit(q); label.z_bits.xor_bit(q); } - Conjugated { label, sign_negative: xq && !zq } + Conjugated { + label, + sign_negative: xq && !zq, + } } -/// SYdg gate on qubit q: X→Z, Y→Y, Z→-X. +/// `SYdg` gate on qubit q: X→Z, Y→Y, Z→-X. #[must_use] pub fn conjugate_sydg(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { let xq = p.x_bits.get_bit(q); @@ -710,17 +885,24 @@ pub fn conjugate_sydg(p: &PauliBitmaskGeneric, q: usize) - label.x_bits.xor_bit(q); label.z_bits.xor_bit(q); } - Conjugated { label, sign_negative: !xq && zq } + Conjugated { + label, + sign_negative: !xq && zq, + } } /// CY (controlled-Y) with control c, target t. /// /// Decomposed as CY = (I⊗SZ) · CX · (I⊗SZdg), so conjugation is: -/// 1. conjugate by SZdg on target +/// 1. conjugate by `SZdg` on target /// 2. conjugate by CX /// 3. conjugate by SZ on target #[must_use] -pub fn conjugate_cy(p: &PauliBitmaskGeneric, c: usize, t: usize) -> Conjugated { +pub fn conjugate_cy( + p: &PauliBitmaskGeneric, + c: usize, + t: usize, +) -> Conjugated { let r1 = conjugate_szdg(p, t); let r2 = conjugate_cx(&r1.label, c, t); let r3 = conjugate_sz(&r2.label, t); @@ -742,14 +924,23 @@ mod tests { assert!(PauliBitmask::x(0).commutes_with(&PauliBitmask::x(1))); assert!(!PauliBitmask::x(0).commutes_with(&PauliBitmask::y(0))); - let a = PauliBitmask { x_bits: 1, z_bits: 2 }; - let b = PauliBitmask { x_bits: 2, z_bits: 1 }; + let a = PauliBitmask { + x_bits: 1, + z_bits: 2, + }; + let b = PauliBitmask { + x_bits: 2, + z_bits: 1, + }; assert!(a.commutes_with(&b)); } #[test] fn test_multiply() { - assert_eq!(PauliBitmask::x(0).multiply(&PauliBitmask::z(0)), PauliBitmask::y(0)); + assert_eq!( + PauliBitmask::x(0).multiply(&PauliBitmask::z(0)), + PauliBitmask::y(0) + ); } #[test] @@ -796,11 +987,23 @@ mod tests { #[test] fn test_cx() { let r = conjugate_cx(&PauliBitmask::x(0), 0, 1); - assert_eq!(r.label, PauliBitmask { x_bits: 0b11, z_bits: 0 }); + assert_eq!( + r.label, + PauliBitmask { + x_bits: 0b11, + z_bits: 0 + } + ); assert!(!r.sign_negative); let r = conjugate_cx(&PauliBitmask::z(1), 0, 1); - assert_eq!(r.label, PauliBitmask { x_bits: 0, z_bits: 0b11 }); + assert_eq!( + r.label, + PauliBitmask { + x_bits: 0, + z_bits: 0b11 + } + ); assert!(!r.sign_negative); let r = conjugate_cx(&PauliBitmask::x(1), 0, 1); @@ -811,7 +1014,13 @@ mod tests { #[test] fn test_cz() { let r = conjugate_cz(&PauliBitmask::x(0), 0, 1); - assert_eq!(r.label, PauliBitmask { x_bits: 1, z_bits: 2 }); + assert_eq!( + r.label, + PauliBitmask { + x_bits: 1, + z_bits: 2 + } + ); assert!(!r.sign_negative); let r = conjugate_cz(&PauliBitmask::z(0), 0, 1); @@ -974,7 +1183,13 @@ mod tests { fn test_cy() { // X_c → X_c Y_t let r = conjugate_cy(&PauliBitmask::x(0), 0, 1); - assert_eq!(r.label, PauliBitmask { x_bits: 0b11, z_bits: 0b10 }); + assert_eq!( + r.label, + PauliBitmask { + x_bits: 0b11, + z_bits: 0b10 + } + ); assert!(!r.sign_negative); // Z_c → Z_c @@ -984,12 +1199,24 @@ mod tests { // X_t → Z_c X_t let r = conjugate_cy(&PauliBitmask::x(1), 0, 1); - assert_eq!(r.label, PauliBitmask { x_bits: 0b10, z_bits: 0b01 }); + assert_eq!( + r.label, + PauliBitmask { + x_bits: 0b10, + z_bits: 0b01 + } + ); assert!(!r.sign_negative); // Z_t → Z_c Z_t let r = conjugate_cy(&PauliBitmask::z(1), 0, 1); - assert_eq!(r.label, PauliBitmask { x_bits: 0, z_bits: 0b11 }); + assert_eq!( + r.label, + PauliBitmask { + x_bits: 0, + z_bits: 0b11 + } + ); assert!(!r.sign_negative); } @@ -1016,17 +1243,34 @@ mod tests { assert_eq!(phase, 0); // Multi-qubit: (X⊗Z) * (Z⊗X) = (XZ)⊗(ZX) = (-iY)⊗(iY) = (-i·i)(Y⊗Y) = Y⊗Y - let a = PauliBitmask { x_bits: 0b01, z_bits: 0b10 }; // XZ - let b = PauliBitmask { x_bits: 0b10, z_bits: 0b01 }; // ZX + let a = PauliBitmask { + x_bits: 0b01, + z_bits: 0b10, + }; // XZ + let b = PauliBitmask { + x_bits: 0b10, + z_bits: 0b01, + }; // ZX let (prod, phase) = a.multiply_with_phase(&b); - assert_eq!(prod, PauliBitmask { x_bits: 0b11, z_bits: 0b11 }); // YY + assert_eq!( + prod, + PauliBitmask { + x_bits: 0b11, + z_bits: 0b11 + } + ); // YY assert_eq!(phase, 0); // (-i)(i) = 1, phase = 3+1 = 4 mod 4 = 0 } #[test] fn test_cy_involution() { // CY is hermitian (CY² = I), so double conjugation should be identity - for p in [PauliBitmask::x(0), PauliBitmask::z(0), PauliBitmask::x(1), PauliBitmask::z(1)] { + for p in [ + PauliBitmask::x(0), + PauliBitmask::z(0), + PauliBitmask::x(1), + PauliBitmask::z(1), + ] { let r1 = conjugate_cy(&p, 0, 1); let r2 = conjugate_cy(&r1.label, 0, 1); assert_eq!(r2.label, p); diff --git a/crates/pecos-decoder-core/src/adaptive.rs b/crates/pecos-decoder-core/src/adaptive.rs index f937797eb..c05d5cc18 100644 --- a/crates/pecos-decoder-core/src/adaptive.rs +++ b/crates/pecos-decoder-core/src/adaptive.rs @@ -24,13 +24,21 @@ use crate::ObservableDecoder; use crate::errors::DecoderError; +type DecoderFactory = dyn FnMut(&str) -> Result, DecoderError>; + +fn fraction(numerator: usize, denominator: usize) -> f64 { + let numerator = u32::try_from(numerator).expect("monitoring count fits in u32"); + let denominator = u32::try_from(denominator).expect("monitoring window fits in u32"); + f64::from(numerator) / f64::from(denominator) +} + /// Adaptive decoder that rebuilds when noise changes. /// /// Holds a decoder factory and the current DEM. When `update_dem` is /// called with a new DEM string, the decoder is rebuilt transparently. pub struct AdaptiveDecoder { decoder: Box, - factory: Box Result, DecoderError>>, + factory: Box, current_dem: String, rebuild_count: usize, /// Calibration monitoring: recent outcomes (true = logical error). @@ -109,7 +117,7 @@ impl AdaptiveDecoder { return false; // Not enough data } let errors = self.recent_outcomes.iter().filter(|&&e| e).count(); - let rate = errors as f64 / self.recent_outcomes.len() as f64; + let rate = fraction(errors, self.recent_outcomes.len()); rate > self.recalibration_threshold } @@ -120,7 +128,7 @@ impl AdaptiveDecoder { return 0.0; } let errors = self.recent_outcomes.iter().filter(|&&e| e).count(); - errors as f64 / self.recent_outcomes.len() as f64 + fraction(errors, self.recent_outcomes.len()) } /// Set the monitoring window size and recalibration threshold. diff --git a/crates/pecos-decoder-core/src/bp_matching.rs b/crates/pecos-decoder-core/src/bp_matching.rs index a8d983f91..7e8f6477f 100644 --- a/crates/pecos-decoder-core/src/bp_matching.rs +++ b/crates/pecos-decoder-core/src/bp_matching.rs @@ -94,32 +94,32 @@ impl crate::ObservableDecoder for BpMat let bp_weights = self.bp.compute_weights(syndrome); if let Some(corr) = &self.correlation - && corr.has_correlations() { - // Two-pass correlated belief-matching. + && corr.has_correlations() + { + // Two-pass correlated belief-matching. - // First pass: decode with BP weights to get matched edges. - let (_, matched_edges) = - self.matching.decode_with_weights(syndrome, &bp_weights)?; + // First pass: decode with BP weights to get matched edges. + let (_, matched_edges) = self.matching.decode_with_weights(syndrome, &bp_weights)?; - // Apply correlation adjustments to BP weights. - self.adjusted_weights.copy_from_slice(&bp_weights); - for &edge_idx in &matched_edges { - if edge_idx < corr.implied_weights.len() { - for iw in &corr.implied_weights[edge_idx] { - if iw.conditional_weight < self.adjusted_weights[iw.target_edge_idx] { - self.adjusted_weights[iw.target_edge_idx] = iw.conditional_weight; - } + // Apply correlation adjustments to BP weights. + self.adjusted_weights.copy_from_slice(&bp_weights); + for &edge_idx in &matched_edges { + if edge_idx < corr.implied_weights.len() { + for iw in &corr.implied_weights[edge_idx] { + if iw.conditional_weight < self.adjusted_weights[iw.target_edge_idx] { + self.adjusted_weights[iw.target_edge_idx] = iw.conditional_weight; } } } - - // Second pass: decode with correlation-adjusted weights. - let (obs, _) = self - .matching - .decode_with_weights(syndrome, &self.adjusted_weights)?; - return Ok(obs); } + // Second pass: decode with correlation-adjusted weights. + let (obs, _) = self + .matching + .decode_with_weights(syndrome, &self.adjusted_weights)?; + return Ok(obs); + } + // Single-pass belief-matching. let (obs, _) = self.matching.decode_with_weights(syndrome, &bp_weights)?; Ok(obs) diff --git a/crates/pecos-decoder-core/src/correlated_reweighting.rs b/crates/pecos-decoder-core/src/correlated_reweighting.rs index 9b88f737d..edbc16633 100644 --- a/crates/pecos-decoder-core/src/correlated_reweighting.rs +++ b/crates/pecos-decoder-core/src/correlated_reweighting.rs @@ -173,9 +173,9 @@ impl EdgeCorrelationTracker { ) -> Vec { let mut adjusted = base_weights.to_vec(); - for j in 0..self.num_edges { + for (j, adjusted_weight) in adjusted.iter_mut().enumerate().take(self.num_edges) { let mut adjustment = 0.0; - for i in 0..self.num_edges { + for (i, matched) in matched_edges.iter().enumerate().take(self.num_edges) { if i == j { continue; } @@ -191,7 +191,7 @@ impl EdgeCorrelationTracker { continue; } - if matched_edges[i] { + if *matched { // Correlated edge is matched -> decrease weight (more likely). // We only adjust for matched edges -- the unmatched term // creates a large positive bias that dominates when most @@ -199,10 +199,10 @@ impl EdgeCorrelationTracker { adjustment -= conditional; } } - adjusted[j] += adjustment; + *adjusted_weight += adjustment; // Clamp to prevent negative weights - if adjusted[j] < 0.0 { - adjusted[j] = 0.0; + if *adjusted_weight < 0.0 { + *adjusted_weight = 0.0; } } diff --git a/crates/pecos-decoder-core/src/correlation_table.rs b/crates/pecos-decoder-core/src/correlation_table.rs index 2016da361..1e2345a5c 100644 --- a/crates/pecos-decoder-core/src/correlation_table.rs +++ b/crates/pecos-decoder-core/src/correlation_table.rs @@ -209,12 +209,13 @@ fn parse_component_edge_key(component: &str) -> Option { let mut detectors: Vec = Vec::new(); for token in component.split_whitespace() { if let Some(d_str) = token.strip_prefix('D') - && let Ok(d) = d_str.parse::() { - detectors.push(d); - } + && let Ok(d) = d_str.parse::() + { + detectors.push(d); + } } + // Pure observables and hyperedges do not define graph edges. match detectors.len() { - 0 => None, // Pure observable, no edge 1 => Some((detectors[0], u32::MAX)), // Boundary edge 2 => { let (a, b) = if detectors[0] <= detectors[1] { @@ -224,7 +225,7 @@ fn parse_component_edge_key(component: &str) -> Option { }; Some((a, b)) } - _ => None, // Hyperedge, skip + _ => None, } } diff --git a/crates/pecos-decoder-core/src/ghost_protocol.rs b/crates/pecos-decoder-core/src/ghost_protocol.rs index dc3abb8dc..44cba87cc 100644 --- a/crates/pecos-decoder-core/src/ghost_protocol.rs +++ b/crates/pecos-decoder-core/src/ghost_protocol.rs @@ -32,7 +32,6 @@ //! - Cain et al. "Fast correlated decoding of transversal logical //! algorithms" (arXiv:2505.13587) - /// A ghost edge: fragment of a cross-qubit hyperedge. /// /// When a measurement error before a transversal CNOT creates a @@ -152,9 +151,10 @@ pub fn extract_ghost_edges_from_dem( let mut det_qubit: BTreeMap = BTreeMap::new(); for (&d, coords) in &coord_map { if coords.len() >= 2 - && let Some(group) = classify_detector(coords[0], coords[1], stab_coords) { - det_qubit.insert(d, group.qubit_idx); - } + && let Some(group) = classify_detector(coords[0], coords[1], stab_coords) + { + det_qubit.insert(d, group.qubit_idx); + } } let mut ghost_edges = Vec::new(); @@ -165,9 +165,8 @@ pub fn extract_ghost_edges_from_dem( continue; } - let close = match line.find(')') { - Some(i) => i, - None => continue, + let Some(close) = line.find(')') else { + continue; }; let prob: f64 = match line[6..close].parse() { @@ -178,9 +177,10 @@ pub fn extract_ghost_edges_from_dem( let mut dets = Vec::new(); for token in line[close + 1..].split_whitespace() { if let Some(d_str) = token.strip_prefix('D') - && let Ok(d) = d_str.parse::() { - dets.push(d); - } + && let Ok(d) = d_str.parse::() + { + dets.push(d); + } } if dets.len() != 3 { diff --git a/crates/pecos-decoder-core/src/k_mwpm.rs b/crates/pecos-decoder-core/src/k_mwpm.rs index 8aea6bd03..7814059f7 100644 --- a/crates/pecos-decoder-core/src/k_mwpm.rs +++ b/crates/pecos-decoder-core/src/k_mwpm.rs @@ -99,9 +99,8 @@ impl ObservableDecoder for KMwpmDecoder { pq.push((Reverse(0), 0)); // Weight 0 for expansion priority (children will have real weights) while predictions.len() < k { - let (_, node_idx) = match pq.pop() { - Some(item) => item, - None => break, // No more candidates + let Some((_, node_idx)) = pq.pop() else { + break; // No more candidates }; // Expand this node: for each matched edge from commit_idx onward, @@ -120,8 +119,8 @@ impl ObservableDecoder for KMwpmDecoder { // Build modified weights: removed edges get infinite weight. let mut weights = vec![0.0f64; self.num_edges]; // Start with original weights for all edges. - for e in 0..self.num_edges { - weights[e] = self.decoder.edge_weight(e); + for (e, weight) in weights.iter_mut().enumerate().take(self.num_edges) { + *weight = self.decoder.edge_weight(e); } // Remove previously removed edges. for &re in &removed_edges { diff --git a/crates/pecos-decoder-core/src/lib.rs b/crates/pecos-decoder-core/src/lib.rs index 293e33327..6ac5e2bba 100644 --- a/crates/pecos-decoder-core/src/lib.rs +++ b/crates/pecos-decoder-core/src/lib.rs @@ -11,6 +11,17 @@ //! - `matrix` - Common matrix types and check matrix traits //! - `dem` - Detector error model traits and utilities +// Decoder prototypes expose public traits while the API is still stabilizing, +// and their metrics/index conversions intentionally cross integer and floating +// domains. Keep this list narrow: mechanical style lints are fixed in code. +#![allow( + clippy::cast_possible_truncation, + clippy::cast_precision_loss, + clippy::missing_errors_doc, + clippy::missing_panics_doc, + clippy::needless_pass_by_value +)] + pub mod adaptive; pub mod advanced; pub mod bp_matching; diff --git a/crates/pecos-decoder-core/src/observable_subgraph.rs b/crates/pecos-decoder-core/src/observable_subgraph.rs index 76dfec131..31ce1480a 100644 --- a/crates/pecos-decoder-core/src/observable_subgraph.rs +++ b/crates/pecos-decoder-core/src/observable_subgraph.rs @@ -143,14 +143,15 @@ impl SparseDem { } } } else if let Some(l_str) = token.strip_prefix('L') - && let Some(l) = parse_u32_fast(l_str.as_bytes()) { - if !obs_set.remove(&l) { - obs_set.insert(l); - } - if l > max_observable { - max_observable = l; - } + && let Some(l) = parse_u32_fast(l_str.as_bytes()) + { + if !obs_set.remove(&l) { + obs_set.insert(l); + } + if l > max_observable { + max_observable = l; } + } } } mechanisms.push(( @@ -373,7 +374,7 @@ pub struct ObservableSubgraph { /// /// Returns error if the DEM is malformed or detector coordinates don't /// match any stabilizer position. - +/// /// Extra time padding around each boundary edge. /// `None` = exact boundary edge times only (default, matches lomatching). /// `Some(r)` = include detectors at times `t ± r` around each boundary @@ -400,15 +401,16 @@ pub fn partition_dem_by_observable_windowed( let mut det_group: Vec> = vec![None; sdem.num_detectors]; let mut group_detectors: BTreeMap> = BTreeMap::new(); - for d in 0..sdem.num_detectors { + for (d, group_slot) in det_group.iter_mut().enumerate().take(sdem.num_detectors) { if let Some(coords) = coord_map.get(&d) - && coords.len() >= 2 { - let (x, y) = (coords[0], coords[1]); - if let Some(group) = classify_detector(x, y, stab_coords) { - det_group[d] = Some(group); - group_detectors.entry(group).or_default().insert(d); - } + && coords.len() >= 2 + { + let (x, y) = (coords[0], coords[1]); + if let Some(group) = classify_detector(x, y, stab_coords) { + *group_slot = Some(group); + group_detectors.entry(group).or_default().insert(d); } + } } // For each observable, find its observing region. diff --git a/crates/pecos-decoder-core/src/perturbed.rs b/crates/pecos-decoder-core/src/perturbed.rs index b14f13a9b..a2fb1e81e 100644 --- a/crates/pecos-decoder-core/src/perturbed.rs +++ b/crates/pecos-decoder-core/src/perturbed.rs @@ -54,18 +54,18 @@ pub fn perturb_dem(dem: &str, sigma: f64, rng: &mut dyn FnMut() -> f64) -> Strin let trimmed = line.trim(); if let Some(rest) = trimmed.strip_prefix("error(") && let Some(close) = rest.find(')') - && let Ok(p) = rest[..close].parse::() { - let u1 = rng().max(1e-10); - let u2 = rng(); - let z = - (-2.0_f64 * u1.ln()).sqrt() * (2.0_f64 * std::f64::consts::PI * u2).cos(); - let factor = (sigma * z).exp(); - let p_new = (p * factor).clamp(1e-15, 0.499); - let _ = write!(out, "error({p_new})"); - out.push_str(&rest[close..]); - out.push('\n'); - continue; - } + && let Ok(p) = rest[..close].parse::() + { + let u1 = rng().max(1e-10); + let u2 = rng(); + let z = (-2.0_f64 * u1.ln()).sqrt() * (2.0_f64 * std::f64::consts::PI * u2).cos(); + let factor = (sigma * z).exp(); + let p_new = (p * factor).clamp(1e-15, 0.499); + let _ = write!(out, "error({p_new})"); + out.push_str(&rest[close..]); + out.push('\n'); + continue; + } out.push_str(trimmed); out.push('\n'); } @@ -179,10 +179,11 @@ mod tests { for line in perturbed.lines() { let trimmed = line.trim(); if let Some(rest) = trimmed.strip_prefix("error(") - && let Some(close) = rest.find(')') { - let p: f64 = rest[..close].parse().unwrap(); - assert!(p > 0.0 && p < 0.5, "p={p} out of bounds"); - } + && let Some(close) = rest.find(')') + { + let p: f64 = rest[..close].parse().unwrap(); + assert!(p > 0.0 && p < 0.5, "p={p} out of bounds"); + } } } diff --git a/crates/pecos-decoder-core/src/windowed_osd.rs b/crates/pecos-decoder-core/src/windowed_osd.rs index b042d8f3a..00e575ffe 100644 --- a/crates/pecos-decoder-core/src/windowed_osd.rs +++ b/crates/pecos-decoder-core/src/windowed_osd.rs @@ -133,10 +133,12 @@ impl WindowedOsdDecoder { for d in 0..num_detectors { if let Some(&t) = det_time.get(&d) - && t >= win_start && t < win_end { - local_to_global.push(d); - is_core.push(t >= t_start && t < core_end); - } + && t >= win_start + && t < win_end + { + local_to_global.push(d); + is_core.push(t >= t_start && t < core_end); + } } if local_to_global.is_empty() { diff --git a/crates/pecos-fusion-blossom/src/core_traits.rs b/crates/pecos-fusion-blossom/src/core_traits.rs index c0a0d451b..ee44d32b4 100644 --- a/crates/pecos-fusion-blossom/src/core_traits.rs +++ b/crates/pecos-fusion-blossom/src/core_traits.rs @@ -78,7 +78,7 @@ impl pecos_decoder_core::erasure::ObservableErasureDecoder for FusionBlossomDeco .decode_with_options(syndrome_data, DecodingOptions::default()) .map_err(|e| pecos_decoder_core::DecoderError::DecodingFailed(e.to_string()))?; - let edge_indices: Vec = result.matched_edges.iter().copied().collect(); + let edge_indices: Vec = result.matched_edges.clone(); Ok(self.obs_mask_from_edges(&edge_indices)) } } @@ -108,7 +108,7 @@ impl pecos_decoder_core::correlated_decoder::MatchingDecoder for FusionBlossomDe .decode_with_options(syndrome_data, DecodingOptions::default()) .map_err(|e| pecos_decoder_core::DecoderError::DecodingFailed(e.to_string()))?; - let edge_indices: Vec = result.matched_edges.iter().copied().collect(); + let edge_indices: Vec = result.matched_edges.clone(); let mask = self.obs_mask_from_edges(&edge_indices); Ok((mask, edge_indices)) @@ -159,7 +159,7 @@ impl pecos_decoder_core::correlated_decoder::MatchingDecoder for FusionBlossomDe .decode_with_options(syndrome_data, DecodingOptions::default()) .map_err(|e| pecos_decoder_core::DecoderError::DecodingFailed(e.to_string()))?; - let edge_indices: Vec = result.matched_edges.iter().copied().collect(); + let edge_indices: Vec = result.matched_edges.clone(); let mask = self.obs_mask_from_edges(&edge_indices); Ok((mask, edge_indices)) diff --git a/crates/pecos-fusion-blossom/src/decoder.rs b/crates/pecos-fusion-blossom/src/decoder.rs index 80ed85ba3..ad05cd961 100644 --- a/crates/pecos-fusion-blossom/src/decoder.rs +++ b/crates/pecos-fusion-blossom/src/decoder.rs @@ -10,9 +10,15 @@ use fusion_blossom::{ util::{EdgeIndex, PartitionConfig, SolverInitializer, SyndromePattern, VertexIndex, Weight}, }; use ndarray::{Array2, ArrayView1}; -use std::collections::HashMap; +use std::collections::{BTreeMap, HashMap}; use std::fmt; +struct ParsedEdgeInfo { + obs: Vec, + prob: f64, + best_prob: f64, +} + /// Solver type selection #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)] pub enum SolverType { @@ -362,8 +368,6 @@ impl FusionBlossomDecoder { parsed: &ParsedCorrelatedDem, weight_factors: Option<&[f64]>, ) -> Result { - use std::collections::BTreeMap; - let config = FusionBlossomConfig { num_nodes: Some(parsed.num_detectors), num_observables: parsed.num_observables, @@ -374,12 +378,7 @@ impl FusionBlossomDecoder { // Deduplicate edges: merge by independent-union probability, // first-observable-wins (stable under perturbation). // Key: (min_node, max_node, is_boundary). Value: (obs, prob, best_prob). - struct EdgeInfo { - obs: Vec, - prob: f64, - best_prob: f64, - } - let mut edge_map: BTreeMap<(usize, usize, bool), EdgeInfo> = BTreeMap::new(); + let mut edge_map: BTreeMap<(usize, usize, bool), ParsedEdgeInfo> = BTreeMap::new(); for (i, (detectors, obs, base_weight)) in parsed.mechanisms.iter().enumerate() { let weight = if let Some(factors) = weight_factors { @@ -407,7 +406,7 @@ impl FusionBlossomDecoder { _ => continue, }; - let entry = edge_map.entry(key).or_insert_with(|| EdgeInfo { + let entry = edge_map.entry(key).or_insert_with(|| ParsedEdgeInfo { obs: obs.clone(), prob, best_prob: prob, @@ -415,7 +414,7 @@ impl FusionBlossomDecoder { // Independent union: P(A or B) = P(A) + P(B) - P(A)*P(B) entry.prob = entry.prob + prob - entry.prob * prob; if prob > entry.best_prob { - entry.obs = obs.clone(); + entry.obs.clone_from(obs); entry.best_prob = prob; } } @@ -473,10 +472,11 @@ impl FusionBlossomDecoder { let mut weight = if p < 1.0 { ((1.0 - p) / p).ln() } else { 0.0 }; if let Some(factors) = weight_factors - && m < factors.len() { - weight *= factors[m]; - weight = weight.max(0.01); - } + && m < factors.len() + { + weight *= factors[m]; + weight = weight.max(0.01); + } match detectors.len() { 1 => { @@ -1107,6 +1107,11 @@ impl FusionBlossomDecoder { /// Fast decode: syndrome bytes -> observable bitmask. /// Uses reusable buffers and pre-computed observable masks. /// Handles padding for boundary node internally. + /// + /// # Errors + /// + /// Returns a `FusionBlossomError` if the solver cannot decode the supplied + /// syndrome. pub fn decode_to_obs_mask(&mut self, syndrome: &[u8]) -> Result { // Build obs masks on first call if self.edge_obs_masks.is_empty() && !self.edge_observables.is_empty() { @@ -1148,7 +1153,7 @@ impl FusionBlossomDecoder { }; // Compute observable mask using pre-computed bitmasks - let edge_indices: Vec = matched_edges.iter().copied().collect(); + let edge_indices: Vec = matched_edges.clone(); let mask = self.obs_mask_from_edges(&edge_indices); Ok(mask) } diff --git a/crates/pecos-mwpf/src/decoder.rs b/crates/pecos-mwpf/src/decoder.rs index f9a278839..244fa6edf 100644 --- a/crates/pecos-mwpf/src/decoder.rs +++ b/crates/pecos-mwpf/src/decoder.rs @@ -24,6 +24,7 @@ use mwpf::mwpf_solver::{ }; use mwpf::util::{HyperEdge, SolverInitializer, SyndromePattern}; use pecos_decoder_core::dem::DemCheckMatrix; +use std::collections::BTreeMap; use std::sync::Arc; /// Which MWPF solver variant to use. @@ -110,6 +111,7 @@ pub struct MwpfDecodingResult { } /// Internal solver enum holding any MWPF solver variant. +#[allow(clippy::large_enum_variant)] // Solver structs are owned to avoid extra solver indirection. enum Solver { UnionFind(SolverSerialUnionFind), SingleHair(SolverSerialSingleHair), @@ -117,6 +119,12 @@ enum Solver { BpHybrid(SolverBPWrapper), } +struct EdgeInfo { + prob: f64, + obs_mask: u64, + best_prob: f64, +} + impl Solver { fn solve(&mut self, syndrome: SyndromePattern) { match self { @@ -181,12 +189,6 @@ impl MwpfDecoder { // Decomposed DEMs can have multiple mechanisms with the same detector set. // Merge by combining probabilities (independent union) and tracking the // observable from the highest-probability mechanism (first-observable-wins). - use std::collections::BTreeMap; - struct EdgeInfo { - prob: f64, - obs_mask: u64, - best_prob: f64, - } let mut edge_map: BTreeMap, EdgeInfo> = BTreeMap::new(); for m in 0..dem.num_mechanisms { let p = dem.error_priors[m]; diff --git a/crates/pecos-phir-json/src/v0_1/ast.rs b/crates/pecos-phir-json/src/v0_1/ast.rs index f61b51a1c..2a81b0aff 100644 --- a/crates/pecos-phir-json/src/v0_1/ast.rs +++ b/crates/pecos-phir-json/src/v0_1/ast.rs @@ -298,8 +298,10 @@ impl<'de> Deserialize<'de> for Operation { .and_then(|v| v.as_str()) .ok_or_else(|| D::Error::custom("missing variable"))? .to_string(); - let size: Option = - obj.get("size").and_then(|v| v.as_u64().map(|n| n as usize)); + let size: Option = obj + .get("size") + .and_then(serde_json::Value::as_u64) + .and_then(|n| usize::try_from(n).ok()); Ok(Operation::VariableDefinition { data, data_type, diff --git a/crates/pecos-qec/src/fault_tolerance/correlation.rs b/crates/pecos-qec/src/fault_tolerance/correlation.rs index 40267737b..7c4430b3e 100644 --- a/crates/pecos-qec/src/fault_tolerance/correlation.rs +++ b/crates/pecos-qec/src/fault_tolerance/correlation.rs @@ -30,11 +30,18 @@ //! for order 3, triple correlations that test whether the DEM's //! independent error decomposition is adequate. -use std::collections::BTreeMap; +use std::collections::{BTreeMap, BTreeSet}; + +type CorrelationEntry<'a> = (&'a Vec, f64, f64); + +fn count_as_f64(items: &[T]) -> f64 { + items.iter().fold(0.0, |count, _| count + 1.0) +} /// Flat `n x n` detector flip frequency matrix. /// /// Stored row-major. Use `index(i, j, n) = i * n + j`. +#[must_use] pub fn flip_matrix_from_fired(fired_per_shot: &[Vec], num_detectors: usize) -> Vec { let n = num_detectors; let shots = fired_per_shot.len(); @@ -42,7 +49,7 @@ pub fn flip_matrix_from_fired(fired_per_shot: &[Vec], num_detectors: usize) return vec![0.0; n * n]; } - let inv = 1.0 / shots as f64; + let inv = 1.0 / count_as_f64(fired_per_shot); let half_inv = 0.5 * inv; let mut m = vec![0.0; n * n]; @@ -70,19 +77,20 @@ pub fn flip_matrix_from_fired(fired_per_shot: &[Vec], num_detectors: usize) /// Per-round flip frequency matrices. /// /// Returns one flat `k x k` matrix per round, where `k = dets_per_round`. +#[must_use] pub fn flip_matrices_by_round( fired_per_shot: &[Vec], num_detectors: usize, dets_per_round: usize, ) -> Vec> { let k = dets_per_round; - let num_rounds = (num_detectors + k - 1) / k; + let num_rounds = num_detectors.div_ceil(k); let shots = fired_per_shot.len(); if shots == 0 { return vec![vec![0.0; k * k]; num_rounds]; } - let inv = 1.0 / shots as f64; + let inv = 1.0 / count_as_f64(fired_per_shot); let half_inv = 0.5 * inv; let mut matrices = vec![vec![0.0; k * k]; num_rounds]; @@ -92,8 +100,11 @@ pub fn flip_matrices_by_round( for &d in fired { let r = d as usize / k; let local = d as usize % k; - if r < num_rounds { - round_local[r].push(local as u32); + if r >= num_rounds { + continue; + } + if let Ok(local) = u32::try_from(local) { + round_local[r].push(local); } } @@ -118,6 +129,7 @@ pub fn flip_matrices_by_round( /// /// Returns a map from sorted detector index tuples to joint firing /// probability. Keys are ordered ascending. +#[must_use] pub fn k_body_rates( fired_per_shot: &[Vec], num_detectors: usize, @@ -128,13 +140,18 @@ pub fn k_body_rates( return BTreeMap::new(); } - let inv = 1.0 / shots as f64; + let inv = 1.0 / count_as_f64(fired_per_shot); let mut rates: BTreeMap, f64> = BTreeMap::new(); for fired in fired_per_shot { - let n = fired.len().min(max_order); + let valid_fired: Vec = fired + .iter() + .copied() + .filter(|&d| (d as usize) < num_detectors) + .collect(); + let n = valid_fired.len().min(max_order); for order in 1..=n { - for_each_combination(fired, order, num_detectors as u32, |combo| { + for_each_combination(&valid_fired, order, |combo| { *rates.entry(combo.to_vec()).or_insert(0.0) += inv; }); } @@ -145,6 +162,7 @@ pub fn k_body_rates( /// Per-round k-body rates. Detector indices in the returned maps are /// round-local (0..dets_per_round-1). +#[must_use] pub fn k_body_rates_by_round( fired_per_shot: &[Vec], num_detectors: usize, @@ -152,13 +170,13 @@ pub fn k_body_rates_by_round( max_order: usize, ) -> Vec, f64>> { let k = dets_per_round; - let num_rounds = (num_detectors + k - 1) / k; + let num_rounds = num_detectors.div_ceil(k); let shots = fired_per_shot.len(); if shots == 0 { return vec![BTreeMap::new(); num_rounds]; } - let inv = 1.0 / shots as f64; + let inv = 1.0 / count_as_f64(fired_per_shot); let mut round_rates: Vec, f64>> = vec![BTreeMap::new(); num_rounds]; for fired in fired_per_shot { @@ -166,8 +184,11 @@ pub fn k_body_rates_by_round( for &d in fired { let r = d as usize / k; let local = d as usize % k; - if r < num_rounds { - round_local[r].push(local as u32); + if r >= num_rounds { + continue; + } + if let Ok(local) = u32::try_from(local) { + round_local[r].push(local); } } @@ -175,7 +196,7 @@ pub fn k_body_rates_by_round( let n = local_ids.len().min(max_order); let rr = &mut round_rates[r]; for order in 1..=n { - for_each_combination(local_ids, order, k as u32, |combo| { + for_each_combination(local_ids, order, |combo| { *rr.entry(combo.to_vec()).or_insert(0.0) += inv; }); } @@ -188,15 +209,16 @@ pub fn k_body_rates_by_round( /// Compare k-body rates between two sets, grouped by order. /// /// Returns a map from order to `(max_rel_error, rms_rel_error, worst_event)`. +#[must_use] pub fn compare_k_body( sim: &BTreeMap, f64>, dem: &BTreeMap, f64>, min_rate: f64, ) -> BTreeMap)> { - let all_keys: BTreeMap<&Vec, ()> = sim.keys().chain(dem.keys()).map(|k| (k, ())).collect(); + let all_keys: BTreeSet<&Vec> = sim.keys().chain(dem.keys()).collect(); - let mut by_order: BTreeMap, f64, f64)>> = BTreeMap::new(); - for (&key, _) in &all_keys { + let mut by_order: BTreeMap>> = BTreeMap::new(); + for &key in &all_keys { let s = sim.get(key).copied().unwrap_or(0.0); let d = dem.get(key).copied().unwrap_or(0.0); by_order.entry(key.len()).or_default().push((key, s, d)); @@ -207,22 +229,22 @@ pub fn compare_k_body( let mut max_err = 0.0_f64; let mut worst: Vec = Vec::new(); let mut sum_sq = 0.0; - let mut count = 0u64; + let mut count = 0.0; for &(key, s, d) in entries { if s > min_rate { let rel = (d / s - 1.0).abs(); if rel > max_err { max_err = rel; - worst = key.clone(); + worst.clone_from(key); } sum_sq += rel * rel; - count += 1; + count += 1.0; } } - let rms = if count > 0 { - (sum_sq / count as f64).sqrt() + let rms = if count > 0.0 { + (sum_sq / count).sqrt() } else { 0.0 }; @@ -233,6 +255,7 @@ pub fn compare_k_body( } /// Compare two flat flip matrices. Returns `(max_rel_err, frob_rel_err, worst_i, worst_j)`. +#[must_use] pub fn compare_flip_matrices( sim: &[f64], dem: &[f64], @@ -289,13 +312,16 @@ pub struct DemMechanism { /// /// Uses iterative proportional fitting on the exact DEM marginal equation: /// -/// p_d = 1/2 - 1/2 * prod_{m: d in S_m} (1 - 2*q_m) +/// ```text +/// p_d = 1/2 - 1/2 * prod_{m: d in S_m} (1 - 2*q_m) +/// ``` /// /// Each iteration computes current marginals, then scales each mechanism /// by the geometric mean of (target/current) ratios for the detectors /// it affects. Mechanisms with no detector overlap are untouched. /// /// Returns the fitted mechanisms and per-detector residual errors. +#[must_use] pub fn fit_dem_to_marginals( mechanisms: &[DemMechanism], target_marginals: &[f64], @@ -356,7 +382,7 @@ pub fn fit_dem_to_marginals( if count == 0 { continue; } - let scale = (log_ratio / count as f64).exp(); + let scale = (log_ratio / f64::from(count)).exp(); let new_q = (q[m] * scale).clamp(0.0, 0.499); max_change = max_change.max((new_q - q[m]).abs()); q[m] = new_q; @@ -392,6 +418,7 @@ pub fn fit_dem_to_marginals( } /// Format fitted mechanisms as a standard DEM string. +#[must_use] pub fn mechanisms_to_dem_string(mechanisms: &[DemMechanism]) -> String { let mut lines = Vec::new(); for mech in mechanisms { @@ -417,9 +444,8 @@ pub fn mechanisms_to_dem_string(mechanisms: &[DemMechanism]) -> String { // --- Internal helpers --- -/// Iterate over all k-combinations of `items` (assumed sorted, < `max_val`), -/// calling `f` with each sorted combination. -fn for_each_combination(items: &[u32], k: usize, _max_val: u32, mut f: impl FnMut(&[u32])) { +/// Iterate over all k-combinations of `items`, calling `f` with each sorted combination. +fn for_each_combination(items: &[u32], k: usize, mut f: impl FnMut(&[u32])) { if k == 0 || items.len() < k { return; } diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs index 254fc01b3..c074e1afb 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs @@ -113,6 +113,7 @@ impl<'a> DemBuilder<'a> { /// /// One-liner for the common case. Reads detector/DEM output definitions /// from circuit metadata. + #[must_use] pub fn from_circuit( circuit: &pecos_quantum::DagCircuit, p1: f64, @@ -126,6 +127,7 @@ impl<'a> DemBuilder<'a> { /// Build a `DetectorErrorModel` from a `TickCircuit` and noise. /// /// Converts to `DagCircuit` internally. + #[must_use] pub fn from_tick_circuit( circuit: &pecos_quantum::TickCircuit, p1: f64, diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index f74910049..dea9e9b0a 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -1798,6 +1798,12 @@ pub(crate) struct SamplingEngineBuilder<'a> { num_tc_measurements: Option, } +struct FaultMechanismContext<'a> { + im_to_tc: Option<&'a [usize]>, + influence_observable_ids: &'a BTreeSet, + num_tc_measurements: usize, +} + impl<'a> SamplingEngineBuilder<'a> { /// Create a new builder from an influence map. #[must_use] @@ -1892,6 +1898,11 @@ impl<'a> SamplingEngineBuilder<'a> { // Build IM -> TC index mapping let im_to_tc = self.build_im_to_tc_mapping(); + let mechanism_context = FaultMechanismContext { + im_to_tc: im_to_tc.as_deref(), + influence_observable_ids: &influence_observable_ids, + num_tc_measurements, + }; // Aggregation map: mechanism -> probability let mut aggregated: BTreeMap = BTreeMap::new(); @@ -1909,9 +1920,7 @@ impl<'a> SamplingEngineBuilder<'a> { loc_idx, Pauli::X, self.p_prep, - im_to_tc.as_deref(), - &influence_observable_ids, - num_tc_measurements, + &mechanism_context, &mut aggregated, ); } @@ -1922,9 +1931,7 @@ impl<'a> SamplingEngineBuilder<'a> { loc_idx, Pauli::X, self.p_meas, - im_to_tc.as_deref(), - &influence_observable_ids, - num_tc_measurements, + &mechanism_context, &mut aggregated, ); } @@ -2109,17 +2116,15 @@ impl<'a> SamplingEngineBuilder<'a> { loc_idx: usize, pauli: Pauli, prob: f64, - im_to_tc: Option<&[usize]>, - influence_observable_ids: &BTreeSet, - num_tc_measurements: usize, + context: &FaultMechanismContext<'_>, aggregated: &mut BTreeMap, ) { let mechanism = self.compute_mechanism( loc_idx, pauli, - im_to_tc, - influence_observable_ids, - num_tc_measurements, + context.im_to_tc, + context.influence_observable_ids, + context.num_tc_measurements, ); if !mechanism.is_empty() { let entry = aggregated.entry(mechanism).or_insert(0.0); diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs index 9ba7a0edf..96a535835 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs @@ -262,7 +262,7 @@ impl ParsedDem { /// Number of tracked operators. #[must_use] pub fn num_tracked_ops(&self) -> u32 { - self.tracked_ops.iter().flatten().count() as u32 + u32::try_from(self.tracked_ops.iter().flatten().count()).unwrap_or(u32::MAX) } fn record_metadata(ops: &mut Vec>, op: DemOutput) { diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs index 5689c1a2c..edc0e253a 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs @@ -55,7 +55,7 @@ pub enum DetectorValidationError { LinearlyDependent { rank: usize, num_detectors: usize }, /// Circuit contains gates not supported by the symbolic determinism analysis. /// Raw measurement mode requires all gates to be in the supported Clifford - /// subset (H, X, Y, Z, SZ, SZdg, CX, CZ, SWAP, MZ, PZ, I). + /// subset (`H`, `X`, `Y`, `Z`, `SZ`, `SZdg`, `CX`, `CZ`, `SWAP`, `MZ`, `PZ`, `I`). UnsupportedGateForDeterminismAnalysis { gate_type: String }, } @@ -276,7 +276,7 @@ pub struct DemSampler { inner: SamplingEngine, /// Which output indices are non-deterministic (true = coin flip, not from mechanisms). - /// Length = num_outputs (full measurement space in raw mode). + /// Length = `num_outputs` (full measurement space in raw mode). non_det_mask: Vec, /// Deterministic measurement dependencies for raw mode. @@ -330,7 +330,8 @@ impl DemSampler { /// ```ignore /// let mut dag = DagCircuit::new(); /// // ... build circuit, add detectors/observables ... - /// let sampler = DemSampler::from_circuit(&dag, NoiseConfig::uniform(0.01))?; + /// let noise = NoiseConfig::uniform(0.01); + /// let sampler = DemSampler::from_circuit(&dag, &noise)?; /// let (det, obs) = sampler.sample(&mut rng); /// ``` /// Build a sampler from a `TickCircuit` and noise parameters. @@ -338,16 +339,21 @@ impl DemSampler { /// Converts to `DagCircuit` internally. Returns detector-mode sampler. pub fn from_tick_circuit( circuit: &pecos_quantum::TickCircuit, - noise: super::types::NoiseConfig, + noise: &super::types::NoiseConfig, ) -> Result { let dag = pecos_quantum::DagCircuit::from(circuit); Self::from_circuit(&dag, noise) } /// Build a sampler from a `DagCircuit` and noise parameters. + /// + /// # Errors + /// + /// Returns [`DetectorValidationError`] when detector metadata is invalid + /// for the circuit's measurement record. pub fn from_circuit( circuit: &pecos_quantum::DagCircuit, - noise: super::types::NoiseConfig, + noise: &super::types::NoiseConfig, ) -> Result { // Build the DetectorErrorModel via DemBuilder (single code path for // DEM computation), then convert to sampler. @@ -536,7 +542,7 @@ impl DemSampler { /// Bit mask selecting observable outputs. /// /// Existing decoder APIs use `u64` observable masks, so outputs with index - /// >= 64 are not representable here and are ignored consistently with the + /// \>= 64 are not representable here and are ignored consistently with the /// existing mask-based paths. #[must_use] pub fn observable_dem_output_mask(&self) -> u64 { @@ -966,22 +972,30 @@ impl<'a> DemSamplerBuilder<'a> { } if !observables.is_empty() && self.observable_records.is_none() { - #[allow(clippy::cast_possible_truncation, clippy::cast_possible_wrap)] - let num_measurements = self.influence_map.measurements.len() as i32; - let records = observables - .iter() - .map(|ann| { - if let AnnotationKind::Observable { measurement_nodes } = &ann.kind { - measurement_nodes - .iter() - .filter_map(|node| node_to_meas_idx.get(node).copied()) - .map(|meas_idx| meas_idx as i32 - num_measurements) - .collect() - } else { - Vec::new() - } - }) - .collect(); + let records = if let Ok(num_measurements) = + i32::try_from(self.influence_map.measurements.len()) + { + observables + .iter() + .map(|ann| { + if let AnnotationKind::Observable { measurement_nodes } = &ann.kind { + measurement_nodes + .iter() + .filter_map(|node| node_to_meas_idx.get(node).copied()) + .filter_map(|meas_idx| { + i32::try_from(meas_idx) + .ok() + .map(|meas_idx| meas_idx - num_measurements) + }) + .collect() + } else { + Vec::new() + } + }) + .collect() + } else { + vec![Vec::new(); observables.len()] + }; self.observable_records = Some(records); } @@ -1259,10 +1273,10 @@ pub(crate) fn gate_location_prob_from_locations( /// Parse detector or observable definitions from JSON. /// -/// Run noiseless symbolic simulation on a TickCircuit to identify non-deterministic measurements. +/// Run noiseless symbolic simulation on a `TickCircuit` to identify non-deterministic measurements. /// /// Returns a Vec where true = non-deterministic (needs coin flip). -/// Uses SymbolicSparseStab which tracks measurement determinism symbolically. +/// Uses `SymbolicSparseStab` which tracks measurement determinism symbolically. /// Run noiseless symbolic simulation to identify non-deterministic measurements /// and their dependency structure. /// @@ -1311,7 +1325,7 @@ fn parse_records_json(json: &str) -> Vec> { /// Extract measurement record indices from a JSON object string. /// -/// Prefers `"meas_ids"` (absolute MeasId IDs) when available. +/// Prefers `"meas_ids"` (absolute `MeasId` IDs) when available. /// Falls back to `"records"` (negative offsets) for legacy compatibility. fn extract_records_array(json: &str) -> Vec { // Prefer meas_ids (absolute, stable IDs from MeasId) @@ -1511,8 +1525,8 @@ mod tests { circuit.h(&[0]); circuit.pauli_operator_labeled("x_check", X(0)); - let sampler = - DemSampler::from_circuit(&circuit, NoiseConfig::new(0.03, 0.0, 0.0, 0.0)).unwrap(); + let noise = NoiseConfig::new(0.03, 0.0, 0.0, 0.0); + let sampler = DemSampler::from_circuit(&circuit, &noise).unwrap(); assert_eq!(sampler.num_tracked_ops(), 1); assert_eq!(sampler.num_observables(), 0); diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs index 161a2e73a..58854fc21 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs @@ -1466,7 +1466,7 @@ pub struct NoiseConfig { /// When set (> 0), idle gates contribute a coherent Z rotation in addition /// to any stochastic idle noise. Idle fault locations with the same /// detector set have their angles accumulated coherently (angles add), - /// giving probability sin²(total_angle/2) instead of independent combination. + /// giving probability `sin²(total_angle/2)` instead of independent combination. /// /// This is the EEG H-type noise model for idle gates. Default is 0.0. pub idle_rz: f64, @@ -1849,31 +1849,25 @@ fn parse_pecos_metadata_dem_output( } } - if let Some(label_value) = object.get("label") { - if !label_value.is_null() { - let label = label_value.as_str().ok_or_else(|| { - PecosDemMetadataError::new(format!( - "DEM output {idx} label is not a string or null" - )) - })?; - dem_output = dem_output.with_label(label); - } + if let Some(label_value) = object.get("label") + && !label_value.is_null() + { + let label = label_value.as_str().ok_or_else(|| { + PecosDemMetadataError::new(format!("DEM output {idx} label is not a string or null")) + })?; + dem_output = dem_output.with_label(label); } - if let Some(pauli_value) = object.get("pauli") { - if !pauli_value.is_null() { - let pauli = pauli_value.as_str().ok_or_else(|| { - PecosDemMetadataError::new(format!( - "DEM output {idx} pauli is not a string or null" - )) - })?; - let pauli = pauli.parse::().map_err(|err| { - PecosDemMetadataError::new(format!( - "DEM output {idx} has invalid PauliString: {err}" - )) - })?; - dem_output = dem_output.with_pauli(pauli); - } + if let Some(pauli_value) = object.get("pauli") + && !pauli_value.is_null() + { + let pauli = pauli_value.as_str().ok_or_else(|| { + PecosDemMetadataError::new(format!("DEM output {idx} pauli is not a string or null")) + })?; + let pauli = pauli.parse::().map_err(|err| { + PecosDemMetadataError::new(format!("DEM output {idx} has invalid PauliString: {err}")) + })?; + dem_output = dem_output.with_pauli(pauli); } let records = if let Some(records_value) = object.get("records") { @@ -1971,6 +1965,12 @@ pub struct DetectorErrorModel { graphlike_decomposable_counts: BTreeMap<(u32, u32), u32>, } +/// Structured DEM mechanism tuple: `(probability, detector_ids, observable_ids)`. +pub type MechanismTuple = (f64, Vec, Vec); + +/// Detector-coordinate tuple: `(detector_id, coordinates)`. +pub type DetectorCoordinateTuple = (u32, Vec); + impl DetectorErrorModel { /// Creates a new empty DEM. #[must_use] @@ -2083,6 +2083,10 @@ impl DetectorErrorModel { /// The standard DEM string remains decoder-compatible and uses ordinary /// `logical_observable L` declarations. This JSON form preserves the /// richer PECOS DEM-output information, including tracked Pauli operators. + /// + /// # Panics + /// + /// Panics only if serializing a JSON value constructed in this method fails. #[must_use] pub fn to_pecos_metadata_json(&self) -> String { let observables: Vec = self @@ -2144,6 +2148,10 @@ impl DetectorErrorModel { /// `pecos_observable {json}` and `pecos_tracked_op {json}` statements. This makes PECOS DEM text a /// strict superset: every Stim DEM remains valid PECOS DEM text, and PECOS /// adds statements for data Stim cannot represent. + /// + /// # Panics + /// + /// Panics only if serializing JSON values constructed in this method fails. #[must_use] pub fn to_pecos_string(&self) -> String { let mut text = self.to_string(); @@ -2752,7 +2760,7 @@ impl DetectorErrorModel { /// Also returns detector coordinate map. This is the structured equivalent of /// `to_string()` — same data, no string intermediary. #[must_use] - pub fn to_mechanisms(&self) -> (Vec<(f64, Vec, Vec)>, Vec<(u32, Vec)>) { + pub fn to_mechanisms(&self) -> (Vec, Vec) { // Group contributions by effect let mut by_effect: BTreeMap = BTreeMap::new(); for contrib in &self.contributions { diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index 65d37fc09..e13e91448 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -177,22 +177,25 @@ pub(crate) enum PauliType { Z, } -/// Build a fault table from a TickCircuit and noise parameters. +/// Build a fault table from a `TickCircuit` and noise parameters. /// /// Each entry describes one possible fault mechanism: its probability and /// which measurements it would flip if it occurs. The table is used for /// independent per-shot Bernoulli sampling. /// -/// Gate ordering follows the TickCircuit tick-by-tick structure, which must +/// Gate ordering follows the `TickCircuit` tick-by-tick structure, which must /// match the measurement numbering used by detector/DEM-output record indices. /// /// # Supported gates /// /// **Fault injection** (noise applied after these gates): -/// - Single-qubit Clifford: H, X, Y, Z, SZ, SZdg, SX, SXdg, SY, SYdg, F, Fdg → p=p1, 3 alternatives -/// - Two-qubit Clifford: CX, CY, CZ, SXX, SXXdg, SYY, SYYdg, SZZ, SZZdg, SWAP → p=p2, 15 alts -/// - State preparation: PZ, QAlloc → mechanism with p=p_prep, 1 alternative (X) -/// - Measurement: MZ, MeasureFree, MeasureLeaked → mechanism with p=p_meas, 1 alternative (flip) +/// - Single-qubit Clifford: `H`, `X`, `Y`, `Z`, `SZ`, `SZdg`, `SX`, `SXdg`, +/// `SY`, `SYdg`, `F`, `Fdg` → `p=p1`, 3 alternatives +/// - Two-qubit Clifford: `CX`, `CY`, `CZ`, `SXX`, `SXXdg`, `SYY`, `SYYdg`, +/// `SZZ`, `SZZdg`, `SWAP` → `p=p2`, 15 alternatives +/// - State preparation: `PZ`, `QAlloc` → mechanism with `p=p_prep`, 1 alternative (`X`) +/// - Measurement: `MZ`, `MeasureFree`, `MeasureLeaked` → mechanism with +/// `p=p_meas`, 1 alternative (flip) /// /// Each mechanism fires at most once per shot (Bernoulli with total probability p). /// When it fires, exactly one alternative is chosen uniformly at random. This @@ -202,14 +205,19 @@ pub(crate) enum PauliType { /// **Propagation** (gates that transform a propagating Pauli): /// - All single-qubit Cliffords: Clifford conjugation via direct Pauli-basis updates /// - All two-qubit Cliffords: Clifford conjugation via direct Pauli-basis updates -/// - PZ, QAlloc: absorbs all Pauli components on the reset qubit -/// - MZ: records X-component flip, then absorbs all components (state collapse) +/// - `PZ`, `QAlloc`: absorbs all Pauli components on the reset qubit +/// - `MZ`: records `X`-component flip, then absorbs all components (state collapse) /// /// **No-op** (pass through without noise or transformation): -/// - I, Idle, QFree, MeasCrosstalkGlobalPayload, MeasCrosstalkLocalPayload, PauliOperatorMeta +/// - `I`, `Idle`, `QFree`, `MeasCrosstalkGlobalPayload`, +/// `MeasCrosstalkLocalPayload`, `PauliOperatorMeta` /// /// Any gate not in the above lists returns [`UnsupportedGateError`]. /// +/// # Errors +/// +/// Returns [`UnsupportedGateError`] when the circuit contains a gate outside +/// the supported Clifford/prep/measurement/metadata set. pub fn build_fault_table( tc: &TickCircuit, noise: &StochasticNoiseParams, @@ -323,7 +331,7 @@ pub fn build_fault_table( Ok(mechanisms) } -/// Validate that all gates in the TickCircuit are supported (before flattening). +/// Validate that all gates in the `TickCircuit` are supported (before flattening). fn validate_tick_circuit(tc: &TickCircuit) -> Result<(), UnsupportedGateError> { for (tick_idx, tick) in tc.ticks().iter().enumerate() { for (gate_idx, gate) in tick.gates().iter().enumerate() { @@ -339,14 +347,14 @@ fn validate_tick_circuit(tc: &TickCircuit) -> Result<(), UnsupportedGateError> { gate_type: gate.gate_type, tick: tick_idx, gate_in_tick: gate_idx, - qubits: gate.qubits.iter().map(|q| q.index()).collect(), + qubits: gate.qubits.iter().map(pecos_core::QubitId::index).collect(), }); } } Ok(()) } -/// Flatten a TickCircuit into a gate list with measurement position tracking. +/// Flatten a `TickCircuit` into a gate list with measurement position tracking. /// /// Multi-qubit gates are split into individual entries so each measurement/pair /// gets its own position for fault injection. Returns the gate list and a map @@ -358,7 +366,7 @@ pub(crate) fn flatten_tick_circuit(tc: &TickCircuit) -> (Vec, HashMap = gate.qubits.iter().map(|q| q.index()).collect(); + let qs: Vec = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); let is_mz = is_supported_measurement_gate(gate.gate_type); let is_2q = is_standard_2q_clifford_gate(gate.gate_type); @@ -417,7 +425,7 @@ pub(crate) fn propagate_single( PauliType::X => prop.track_x(&[qubit]), PauliType::Y => prop.track_y(&[qubit]), PauliType::Z => prop.track_z(&[qubit]), - }; + } propagate_forward(&mut prop, start, gates, meas_positions) } @@ -435,7 +443,7 @@ fn propagate_single_effect( PauliType::X => prop.track_x(&[qubit]), PauliType::Y => prop.track_y(&[qubit]), PauliType::Z => prop.track_z(&[qubit]), - }; + } let affected_measurements = propagate_forward(&mut prop, start, gates, meas_positions); let affected_tracked_ops = tracked_ops_flipped_by(&prop, tracked_ops); @@ -460,37 +468,31 @@ fn propagate_pair( PauliType::X => prop.track_x(&[q1]), PauliType::Y => prop.track_y(&[q1]), PauliType::Z => prop.track_z(&[q1]), - }; + } match p2 { PauliType::X => prop.track_x(&[q2]), PauliType::Y => prop.track_y(&[q2]), PauliType::Z => prop.track_z(&[q2]), - }; + } propagate_forward(&mut prop, start, gates, meas_positions) } fn propagate_pair_effect( - p1: PauliType, - q1: usize, - p2: PauliType, - q2: usize, + faults: [(PauliType, usize); 2], start: usize, gates: &[GateLoc], meas_positions: &HashMap, tracked_ops: &[PauliString], ) -> PropagatedFaultEffect { let mut prop = PauliProp::new(); - match p1 { - PauliType::X => prop.track_x(&[q1]), - PauliType::Y => prop.track_y(&[q1]), - PauliType::Z => prop.track_z(&[q1]), - }; - match p2 { - PauliType::X => prop.track_x(&[q2]), - PauliType::Y => prop.track_y(&[q2]), - PauliType::Z => prop.track_z(&[q2]), - }; + for (pauli, qubit) in faults { + match pauli { + PauliType::X => prop.track_x(&[qubit]), + PauliType::Y => prop.track_y(&[qubit]), + PauliType::Z => prop.track_z(&[qubit]), + } + } let affected_measurements = propagate_forward(&mut prop, start, gates, meas_positions); let affected_tracked_ops = tracked_ops_flipped_by(&prop, tracked_ops); @@ -592,10 +594,10 @@ fn propagate_forward( if !loc.qubits.is_empty() => { let q = loc.qubits[0]; - if prop.contains_x(q) { - if let Some(&meas_idx) = meas_positions.get(&loc_idx) { - affected.insert(meas_idx); - } + if prop.contains_x(q) + && let Some(&meas_idx) = meas_positions.get(&loc_idx) + { + affected.insert(meas_idx); } prop.clear_qubit(q); } @@ -624,13 +626,13 @@ pub enum FaultKind { /// Which noise channel produced this fault location. #[derive(Clone, Debug, PartialEq, Eq)] pub enum FaultChannel { - /// Single-qubit depolarizing (p1). + /// Single-qubit depolarizing (`p1`). P1, - /// Two-qubit depolarizing (p2). + /// Two-qubit depolarizing (`p2`). P2, - /// Measurement flip (p_meas). + /// Measurement flip (`p_meas`). PMeas, - /// State preparation flip (p_prep). + /// State preparation flip (`p_prep`). PPrep, } @@ -649,20 +651,20 @@ pub struct FaultAlternative { pub affected_observables: Vec, /// Tracked-operator indices flipped. pub affected_tracked_ops: Vec, - /// Probability of this alternative conditioned on the mechanism firing (1/k). + /// Probability of this alternative conditioned on the mechanism firing (`1/k`). pub conditional_probability: f64, - /// Marginal probability of this specific alternative at this location: p_i / k_i. + /// Marginal probability of this specific alternative at this location: `p_i / k_i`. /// /// This is NOT "probability of this fault and no others." A full-circuit - /// configuration probability requires multiplying by (1 - p_j) for all - /// other locations j. + /// configuration probability requires multiplying by `(1 - p_j)` for all + /// other locations `j`. pub absolute_probability: f64, } /// A physical fault location in the circuit. #[derive(Clone, Debug)] pub struct FaultLocation { - /// Tick index in the TickCircuit. + /// Tick index in the `TickCircuit`. pub tick: usize, /// Gate index within the tick. pub gate_index: usize, @@ -672,11 +674,11 @@ pub struct FaultLocation { pub qubits: Vec, /// Which noise channel this location belongs to. pub channel: FaultChannel, - /// Total probability that this mechanism fires: p_i. + /// Total probability that this mechanism fires: `p_i`. pub channel_probability: f64, - /// Probability that no fault occurs at this location: 1 - p_i. + /// Probability that no fault occurs at this location: `1 - p_i`. pub no_fault_probability: f64, - /// Number of fault alternatives at this location: k_i. + /// Number of fault alternatives at this location: `k_i`. pub num_alternatives: usize, /// All fault alternatives at this location. pub faults: Vec, @@ -690,15 +692,17 @@ pub struct FaultLocation { /// /// Probability model (independent mechanisms): /// -/// For location i with k_i alternatives: -/// - `channel_probability` = p_i (total probability mechanism fires) -/// - `no_fault_probability` = 1 - p_i -/// - `conditional_probability` = 1/k_i (uniform alternative choice) -/// - `absolute_probability` = p_i / k_i (marginal alternative probability) +/// For location `i` with `k_i` alternatives: +/// - `channel_probability` = `p_i` (total probability mechanism fires) +/// - `no_fault_probability` = `1 - p_i` +/// - `conditional_probability` = `1/k_i` (uniform alternative choice) +/// - `absolute_probability` = `p_i / k_i` (marginal alternative probability) /// /// Full-circuit configuration probability for "alternative j at location i, /// no fault at all other locations": -/// P = (p_i / k_i) * product_{m != i} (1 - p_m) +/// ```text +/// P = (p_i / k_i) * product_{m != i} (1 - p_m) +/// ``` #[derive(Clone, Debug)] pub struct FaultCatalog { pub locations: Vec, @@ -719,9 +723,9 @@ pub struct FaultConfiguration { pub affected_observables: Vec, /// Combined tracked-operator indices (XOR parity). pub affected_tracked_ops: Vec, - /// Product of selected alternatives' absolute_probability. + /// Product of selected alternatives' `absolute_probability`. pub selected_probability: f64, - /// selected_probability * product of unselected locations' no_fault_probability. + /// `selected_probability * product(unselected no_fault_probability)`. pub configuration_probability: f64, } @@ -733,6 +737,7 @@ impl FaultCatalog { /// XOR parity. Probabilities follow the independent-mechanism model. /// /// For k=0: yields one no-fault event. + #[must_use] pub fn fault_configurations(&self, k: usize) -> FaultConfigurationIter<'_> { FaultConfigurationIter::new(self, k) } @@ -805,7 +810,7 @@ impl FaultConfigCursor { false } - /// Build a FaultConfiguration from the current cursor state + catalog data. + /// Build a `FaultConfiguration` from the current cursor state + catalog data. fn build(&self, catalog: &FaultCatalog) -> FaultConfiguration { if self.k == 0 { let no_fault_prob: f64 = catalog @@ -916,7 +921,7 @@ impl<'a> FaultConfigurationIter<'a> { } } -impl<'a> Iterator for FaultConfigurationIter<'a> { +impl Iterator for FaultConfigurationIter<'_> { type Item = FaultConfiguration; fn next(&mut self) -> Option { self.cursor.next_config(self.catalog) @@ -924,7 +929,7 @@ impl<'a> Iterator for FaultConfigurationIter<'a> { } /// Owned k-fault configuration iterator (no lifetime borrows). -/// Suitable for FFI / PyO3 where lifetimes are not expressible. +/// Suitable for FFI / `PyO3` where lifetimes are not expressible. pub struct OwnedFaultConfigIter { catalog: FaultCatalog, cursor: FaultConfigCursor, @@ -932,6 +937,7 @@ pub struct OwnedFaultConfigIter { impl OwnedFaultConfigIter { /// Create from an owned catalog clone. + #[must_use] pub fn new(catalog: FaultCatalog, k: usize) -> Self { let cursor = FaultConfigCursor::new(catalog.locations.len(), k, |i| { catalog.locations[i].faults.len() @@ -947,13 +953,18 @@ impl Iterator for OwnedFaultConfigIter { } } -/// Build a fault catalog from a TickCircuit and noise parameters. +/// Build a fault catalog from a `TickCircuit` and noise parameters. /// /// Returns per-location, per-alternative fault data including Pauli labels, /// affected detectors, observables, tracked operators, and probability fields. /// /// Reads detector/observable metadata and tracked-operator annotations /// from the circuit when present. +/// +/// # Errors +/// +/// Returns [`UnsupportedGateError`] when the circuit contains a gate outside +/// the supported Clifford/prep/measurement/metadata set. pub fn build_fault_catalog( tc: &TickCircuit, noise: &StochasticNoiseParams, @@ -974,7 +985,7 @@ pub fn build_fault_catalog( None } }) - .unwrap_or_else(|| meas_positions.len()); + .unwrap_or(meas_positions.len()); let mut locations = Vec::new(); @@ -993,7 +1004,7 @@ pub fn build_fault_catalog( let mut orig_idx = 0; for tick in tc.ticks() { for gate in tick.gates() { - let qs: Vec = gate.qubits.iter().map(|q| q.index()).collect(); + let qs: Vec = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); let is_mz = is_supported_measurement_gate(gate.gate_type); let is_2q = is_standard_2q_clifford_gate(gate.gate_type); let (tick_idx, gate_idx) = tick_gate_map[orig_idx]; @@ -1036,6 +1047,8 @@ pub fn build_fault_catalog( { let q = loc.qubits[0]; let num_alts = 3; + let conditional_probability = 1.0 / 3.0; + let absolute_probability = noise.p1 / 3.0; let mut faults = Vec::with_capacity(num_alts); for &pt in &pauli_types { let effect = propagate_single_effect( @@ -1056,8 +1069,8 @@ pub fn build_fault_catalog( affected_detectors: dets, affected_observables: obs, affected_tracked_ops: tracked, - conditional_probability: 1.0 / num_alts as f64, - absolute_probability: noise.p1 / num_alts as f64, + conditional_probability, + absolute_probability, }); } // Include all locations with nonzero channel probability (even no-effect ones) @@ -1082,16 +1095,15 @@ pub fn build_fault_catalog( { let (q1, q2) = (loc.qubits[0], loc.qubits[1]); let num_alts = 15; + let conditional_probability = 1.0 / 15.0; + let absolute_probability = noise.p2 / 15.0; let mut faults = Vec::with_capacity(num_alts); // 9 two-qubit pairs for &p1 in &pauli_types { for &p2 in &pauli_types { let effect = propagate_pair_effect( - p1, - q1, - p2, - q2, + [(p1, q1), (p2, q2)], loc_idx + 1, &gates, &meas_positions, @@ -1107,8 +1119,8 @@ pub fn build_fault_catalog( affected_detectors: dets, affected_observables: obs, affected_tracked_ops: tracked, - conditional_probability: 1.0 / num_alts as f64, - absolute_probability: noise.p2 / num_alts as f64, + conditional_probability, + absolute_probability, }); } } @@ -1132,8 +1144,8 @@ pub fn build_fault_catalog( affected_detectors: dets, affected_observables: obs, affected_tracked_ops: tracked, - conditional_probability: 1.0 / num_alts as f64, - absolute_probability: noise.p2 / num_alts as f64, + conditional_probability, + absolute_probability, }); let effect = propagate_single_effect( @@ -1154,8 +1166,8 @@ pub fn build_fault_catalog( affected_detectors: dets, affected_observables: obs, affected_tracked_ops: tracked, - conditional_probability: 1.0 / num_alts as f64, - absolute_probability: noise.p2 / num_alts as f64, + conditional_probability, + absolute_probability, }); } let n_alts = faults.len(); @@ -1271,11 +1283,10 @@ fn pauli_pair_to_string(p1: PauliType, q1: usize, p2: PauliType, q2: usize) -> P } fn parse_records_from_meta(tc: &TickCircuit, key: &str) -> Vec> { - let json = match tc.get_meta(key) { - Some(pecos_quantum::Attribute::String(s)) => s, - _ => return Vec::new(), + let Some(pecos_quantum::Attribute::String(json)) = tc.get_meta(key) else { + return Vec::new(); }; - parse_records_array_list(&json) + parse_records_array_list(json) } fn parse_detector_records(tc: &TickCircuit) -> Vec> { @@ -1318,7 +1329,7 @@ fn tracked_ops_flipped_by(prop: &PauliProp, tracked_ops: &[PauliString]) -> Vec< .collect() } -/// Simple parser for `[{"records": [...]}, ...]` JSON without serde_json. +/// Simple parser for `[{"records": [...]}, ...]` JSON without `serde_json`. fn parse_records_array_list(json: &str) -> Vec> { let json = json.trim(); if json.is_empty() || json == "[]" { @@ -1349,6 +1360,12 @@ fn parse_records_array_list(json: &str) -> Vec> { results } +fn record_absolute_index(num_meas: usize, rec: i32) -> Option { + let base = i64::try_from(num_meas).ok()?; + let abs_idx = base.checked_add(i64::from(rec))?; + usize::try_from(abs_idx).ok() +} + /// Map measurement effects to detector effects via record XOR. fn measurements_to_detectors( affected_meas: &[usize], @@ -1359,8 +1376,9 @@ fn measurements_to_detectors( for (det_idx, records) in det_records.iter().enumerate() { let mut parity = 0u8; for &rec in records { - let abs_idx = (num_meas as i32 + rec) as usize; - if affected_meas.contains(&abs_idx) { + if let Some(abs_idx) = record_absolute_index(num_meas, rec) + && affected_meas.contains(&abs_idx) + { parity ^= 1; } } @@ -1381,8 +1399,9 @@ fn measurements_to_observables( for (obs_idx, records) in obs_records.iter().enumerate() { let mut parity = 0u8; for &rec in records { - let abs_idx = (num_meas as i32 + rec) as usize; - if affected_meas.contains(&abs_idx) { + if let Some(abs_idx) = record_absolute_index(num_meas, rec) + && affected_meas.contains(&abs_idx) + { parity ^= 1; } } @@ -1413,11 +1432,16 @@ fn catalog_effect_parts( /// semantics, returning the `MeasurementHistory` with correct cross-reset /// correlations. /// -/// Iterates tick-by-tick to match the TickCircuit's measurement numbering +/// Iterates tick-by-tick to match the `TickCircuit`'s measurement numbering /// (which detector/DEM-output record indices reference). /// /// Errors on unsupported gates with tick/gate/qubit context (same gate set /// as [`build_fault_table`]). +/// +/// # Errors +/// +/// Returns [`UnsupportedGateError`] when the circuit contains a gate outside +/// the supported Clifford/prep/measurement/metadata set. pub fn symbolic_measurement_history( tc: &TickCircuit, ) -> Result { @@ -1436,7 +1460,7 @@ pub fn symbolic_measurement_history( for (tick_idx, tick) in tc.ticks().iter().enumerate() { for (gate_idx, gate) in tick.gates().iter().enumerate() { - let qs: Vec = gate.qubits.iter().map(|q| q.index()).collect(); + let qs: Vec = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); match gate.gate_type { GateType::PZ | GateType::QAlloc => { @@ -1600,6 +1624,7 @@ pub struct RawMeasurementPlan { impl RawMeasurementPlan { /// Build a plan from a measurement history and fault mechanisms. + #[must_use] pub fn new(history: &MeasurementHistory, mechanisms: Vec) -> Self { let kinds = MeasurementKind::from_history(history); let inv_log_1_minus_p = mechanisms @@ -1625,6 +1650,7 @@ impl RawMeasurementPlan { /// /// Returns a `SampleResult` for compatibility with existing code. /// For r-event access, use [`sample_raw`]. + #[must_use] pub fn sample(&self, shots: usize, seed: u64) -> SampleResult { let raw = self.sample_raw(shots, seed); SampleResult::new(raw.columns, shots) @@ -1635,6 +1661,7 @@ impl RawMeasurementPlan { /// Physical mechanisms use geometric skip: O(p * shots) RNG calls per /// mechanism, not O(shots). For typical QEC noise (p ~ 0.005, 20k shots), /// this is ~100 firings per mechanism vs 20000 iterations. + #[must_use] pub fn sample_raw(&self, shots: usize, seed: u64) -> RawSampleResult { if shots == 0 { let r_source_measurements = self.r_source_indices(); @@ -1686,7 +1713,7 @@ impl RawMeasurementPlan { } /// Sample base measurement values from r-sources and constants. - /// Returns (measurement_columns, r_source_columns). + /// Returns (`measurement_columns`, `r_source_columns`). fn sample_base(&self, num_words: usize, rng: &mut PecosRng) -> (Vec>, Vec>) { let mut columns: Vec> = Vec::with_capacity(self.num_measurements); let mut r_columns: Vec> = Vec::new(); diff --git a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs index d24ba4c95..fb381d89c 100644 --- a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs @@ -38,6 +38,13 @@ use pecos_simulators::{PauliProp, SymbolicSparseStab}; use smallvec::SmallVec; use std::collections::BinaryHeap; +struct ObservablePropagationWork<'a> { + recorder: &'a mut CompoundRecorder, + visited: &'a mut [bool], + active_qubits: &'a mut [bool], + heap: &'a mut BinaryHeap<(usize, usize)>, +} + /// Builder for fault influence maps with proper detector definitions. /// /// This integrates forward symbolic simulation with backward propagation @@ -186,7 +193,7 @@ impl<'a> InfluenceBuilder<'a> { for &meas_node in measurement_nodes { if let Some(gate) = circuit.gate(meas_node) { let qubits: Vec = - gate.qubits.iter().map(|q| q.index()).collect(); + gate.qubits.iter().map(pecos_core::QubitId::index).collect(); terms.push(PauliPropagationTerm { pauli: PauliString::zs(&qubits), start_node: Some(meas_node), @@ -513,17 +520,17 @@ impl<'a> InfluenceBuilder<'a> { _ => continue, }; - if !gate.meas_ids.is_empty() { - for (i, qubit) in gate.qubits.iter().enumerate() { - let mr = gate.meas_ids.get(i).copied(); - let sort_key = mr.map(|m| m.index()).unwrap_or(usize::MAX); - entries.push((sort_key, node, qubit.index(), basis, mr)); - } - } else { + if gate.meas_ids.is_empty() { let topo_pos = propagator.topo_position(node); for qubit in &gate.qubits { entries.push((topo_pos, node, qubit.index(), basis, None)); } + } else { + for (i, qubit) in gate.qubits.iter().enumerate() { + let mr = gate.meas_ids.get(i).copied(); + let sort_key = mr.map_or(usize::MAX, pecos_core::MeasId::index); + entries.push((sort_key, node, qubit.index(), basis, mr)); + } } } } @@ -561,6 +568,12 @@ impl<'a> InfluenceBuilder<'a> { let mut visited = vec![false; max_node + 1]; let mut active_qubits = vec![false; max_qubit + 1]; let mut heap = BinaryHeap::new(); + let mut work = ObservablePropagationWork { + recorder, + visited: &mut visited, + active_qubits: &mut active_qubits, + heap: &mut heap, + }; for (det_idx, detector) in detectors.iter().enumerate() { // Build combined Pauli from all measurements in the detector @@ -587,10 +600,7 @@ impl<'a> InfluenceBuilder<'a> { &combined_prop, det_idx, true, // is_detector - recorder, - &mut visited, - &mut active_qubits, - &mut heap, + &mut work, None, // detectors: walk from circuit end ); } @@ -613,6 +623,12 @@ impl<'a> InfluenceBuilder<'a> { let mut visited = vec![false; max_node + 1]; let mut active_qubits = vec![false; max_qubit + 1]; let mut heap = BinaryHeap::new(); + let mut work = ObservablePropagationWork { + recorder, + visited: &mut visited, + active_qubits: &mut active_qubits, + heap: &mut heap, + }; for (dem_output_idx, output) in self.non_detector_outputs.iter().enumerate() { for term in &output.terms { @@ -638,10 +654,7 @@ impl<'a> InfluenceBuilder<'a> { &prop, dem_output_idx, false, // is_detector = false (this is a DEM output) - recorder, - &mut visited, - &mut active_qubits, - &mut heap, + &mut work, start_pos, ); } @@ -653,27 +666,23 @@ impl<'a> InfluenceBuilder<'a> { /// When `start_topo_pos` is `Some(pos)`, only gates at or before that /// topological position are considered. This makes Pauli operator /// annotations positional: only faults before the meta-gate affect it. - #[allow(clippy::too_many_arguments)] fn propagate_observable( propagator: &DagPropagator<'_>, initial_prop: &PauliProp, target_idx: usize, is_detector: bool, - recorder: &mut CompoundRecorder, - visited: &mut [bool], - active_qubits: &mut [bool], - heap: &mut BinaryHeap<(usize, usize)>, + work: &mut ObservablePropagationWork<'_>, start_topo_pos: Option, ) { // Clear work arrays - visited.fill(false); - active_qubits.fill(false); - heap.clear(); + work.visited.fill(false); + work.active_qubits.fill(false); + work.heap.clear(); let mut prop = initial_prop.clone(); // Initialize active qubits from the observable - for (q, is_active) in active_qubits.iter_mut().enumerate() { + for (q, is_active) in work.active_qubits.iter_mut().enumerate() { if prop.contains_x(q) || prop.contains_z(q) { *is_active = true; @@ -682,9 +691,9 @@ impl<'a> InfluenceBuilder<'a> { if start_topo_pos.is_some_and(|max| topo_pos > max) { continue; } - if !visited[node] { - visited[node] = true; - heap.push((topo_pos, node)); + if !work.visited[node] { + work.visited[node] = true; + work.heap.push((topo_pos, node)); } } } @@ -694,18 +703,24 @@ impl<'a> InfluenceBuilder<'a> { let loc_map = Self::build_location_map(propagator); // Process gates in reverse topological order - while let Some((_, node)) = heap.pop() { + while let Some((_, node)) = work.heap.pop() { if let Some(gate) = propagator.gate(node) { // Record per-qubit influences at before=false location if let Some(qubit_locs) = loc_map.get(&(node, false)) { - Self::record_influence(&prop, qubit_locs, target_idx, is_detector, recorder); + Self::record_influence( + &prop, + qubit_locs, + target_idx, + is_detector, + &mut *work.recorder, + ); } // Track which qubits were active before the gate let mut was_active = [false; 8]; for (j, q) in gate.qubits.iter().enumerate() { - if j < was_active.len() && q.index() < active_qubits.len() { - was_active[j] = active_qubits[q.index()]; + if j < was_active.len() && q.index() < work.active_qubits.len() { + was_active[j] = work.active_qubits[q.index()]; } } @@ -726,8 +741,8 @@ impl<'a> InfluenceBuilder<'a> { if prop.contains_z(qi) { prop.track_z(&[qi]); } - if qi < active_qubits.len() { - active_qubits[qi] = false; + if qi < work.active_qubits.len() { + work.active_qubits[qi] = false; } } continue; // don't propagate further on these qubits @@ -738,24 +753,30 @@ impl<'a> InfluenceBuilder<'a> { // Record per-qubit influences at before=true location if let Some(qubit_locs) = loc_map.get(&(node, true)) { - Self::record_influence(&prop, qubit_locs, target_idx, is_detector, recorder); + Self::record_influence( + &prop, + qubit_locs, + target_idx, + is_detector, + &mut *work.recorder, + ); } // Check if Pauli spread to new qubits let node_topo_pos = propagator.topo_position(node); for (j, q) in gate.qubits.iter().enumerate() { let idx = q.index(); - if idx < active_qubits.len() { + if idx < work.active_qubits.len() { let now_active = prop.contains_x(idx) || prop.contains_z(idx); let was = j < was_active.len() && was_active[j]; if now_active && !was { // Pauli spread to this qubit - add its gates - active_qubits[idx] = true; + work.active_qubits[idx] = true; for (topo_pos, pred_node) in propagator.qubit_gates_backward(idx) { - if topo_pos < node_topo_pos && !visited[pred_node] { - visited[pred_node] = true; - heap.push((topo_pos, pred_node)); + if topo_pos < node_topo_pos && !work.visited[pred_node] { + work.visited[pred_node] = true; + work.heap.push((topo_pos, pred_node)); } } } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs b/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs index a18132066..454f5d140 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs @@ -88,6 +88,13 @@ pub struct PropagationBuffers { pub heap: BinaryHeap<(usize, usize)>, } +struct Phase1Request { + meas_node: usize, + meas_qubit: usize, + basis: u8, + detector_idx: usize, +} + // ============================================================================ // Fault Locations (SoA Layout) // ============================================================================ @@ -564,12 +571,12 @@ pub struct DagFaultInfluenceMap { pub detectors: Vec, /// All measurements in the circuit (node, qubit, basis). - /// Ordered by MeasId when gates carry MeasId values. + /// Ordered by `MeasId` when gates carry `MeasId` values. pub measurements: Vec<(usize, usize, u8)>, - /// MeasId IDs for each measurement, in the same order as `measurements`. + /// `MeasId` IDs for each measurement, in the same order as `measurements`. /// When populated, `meas_ids[i]` is the stable identity of `measurements[i]`. - /// Empty for legacy circuits without MeasId on gates. + /// Empty for legacy circuits without `MeasId` on gates. pub meas_ids: Vec, /// Optional labels for non-detector parity outputs. @@ -759,8 +766,9 @@ impl DagFaultInfluenceMap { self.influences.dem_outputs_x = other.influences.dem_outputs_x.clone(); self.influences.dem_outputs_y = other.influences.dem_outputs_y.clone(); self.influences.dem_outputs_z = other.influences.dem_outputs_z.clone(); - self.dem_output_labels = other.dem_output_labels.clone(); - self.dem_output_metadata = other.dem_output_metadata.clone(); + self.dem_output_labels.clone_from(&other.dem_output_labels); + self.dem_output_metadata + .clone_from(&other.dem_output_metadata); } /// Returns the location at the given index. @@ -1023,7 +1031,7 @@ impl FaultEffect { /// Compose two fault effects (as if both faults occurred). /// /// - Paulis are multiplied (handles same-qubit algebra + tensor product) - /// - Detectors/dem_outputs/measurements are XOR'd (symmetric difference) + /// - Detectors, `dem_outputs`, and measurements are XOR'd (symmetric difference) /// /// This is the building block for weight-w fault analysis: /// ```ignore @@ -1116,7 +1124,7 @@ impl GateFaultLocation<'_> { /// All physically possible fault events, including those with no effect. /// /// Use this for probability-correct enumeration (e.g., ML decoder). - /// Events with empty detectors and dem_outputs are "trivial" faults that + /// Events with empty detectors and `dem_outputs` are "trivial" faults that /// happen with real probability but don't change any observable. #[must_use] pub fn all_events(&self) -> Vec { @@ -1824,10 +1832,10 @@ impl<'a> DagFaultAnalyzer<'a> { /// lower-indexed qubits appear first when they are in the same "layer" of /// the circuit. #[must_use] - /// Extract measurements with optional MeasId IDs. + /// Extract measurements with optional `MeasId` IDs. /// /// Returns `(measurements, meas_ids)` where: - /// - `measurements` is `Vec<(node, qubit, basis)>` in MeasId order + /// - `measurements` is `Vec<(node, qubit, basis)>` in `MeasId` order /// - `meas_ids` is `Vec` (empty for legacy circuits) pub fn extract_measurements(&self) -> (Vec<(usize, usize, u8)>, Vec) { let mut entries = Vec::new(); // (sort_key, qubit, node, basis, Option) @@ -1839,17 +1847,17 @@ impl<'a> DagFaultAnalyzer<'a> { _ => continue, }; - if !gate.meas_ids.is_empty() { - for (i, qubit) in gate.qubits.iter().enumerate() { - let mr = gate.meas_ids.get(i).copied(); - let sort_key = mr.map(|m| m.index()).unwrap_or(usize::MAX); - entries.push((sort_key, qubit.index(), node, basis, mr)); - } - } else { + if gate.meas_ids.is_empty() { let topo_pos = self.propagator.topo_position(node); for qubit in &gate.qubits { entries.push((topo_pos, qubit.index(), node, basis, None)); } + } else { + for (i, qubit) in gate.qubits.iter().enumerate() { + let mr = gate.meas_ids.get(i).copied(); + let sort_key = mr.map_or(usize::MAX, pecos_core::MeasId::index); + entries.push((sort_key, qubit.index(), node, basis, mr)); + } } } } @@ -2035,7 +2043,7 @@ impl<'a> DagFaultAnalyzer<'a> { /// Captured influence entry from Phase 2 (shared tail below PZ). /// Stored with `topo_pos` for prefix slicing across measurements. - + /// /// Phase 1: propagate from MZ backward through within-round gates, /// stopping at the ancilla's PZ. Records influences normally. /// Returns the PZ node's topo position, or None if no PZ was hit. @@ -2044,10 +2052,7 @@ impl<'a> DagFaultAnalyzer<'a> { /// the PZ — ready for Phase 2. fn propagate_phase1( &self, - meas_node: usize, - meas_qubit: usize, - basis: u8, - detector_idx: usize, + request: &Phase1Request, recorder: &mut R, work: &mut PropagationBuffers, prop: &mut PauliProp, @@ -2060,18 +2065,24 @@ impl<'a> DagFaultAnalyzer<'a> { heap.clear(); *prop = PauliProp::new(); - if basis == 0 { - prop.track_z(&[meas_qubit]); + if request.basis == 0 { + prop.track_z(&[request.meas_qubit]); } else { - prop.track_x(&[meas_qubit]); + prop.track_x(&[request.meas_qubit]); } - let meas_topo_pos = self.propagator.topo_position(meas_node); - self.record_at_node_generic(meas_node, prop, detector_idx, recorder, true); + let meas_topo_pos = self.propagator.topo_position(request.meas_node); + self.record_at_node_generic( + request.meas_node, + prop, + request.detector_idx, + recorder, + true, + ); - if meas_qubit <= self.max_qubit() { - active_qubits[meas_qubit] = true; - for (topo_pos, node) in self.propagator.qubit_gates_backward(meas_qubit) { + if request.meas_qubit <= self.max_qubit() { + active_qubits[request.meas_qubit] = true; + for (topo_pos, node) in self.propagator.qubit_gates_backward(request.meas_qubit) { if topo_pos < meas_topo_pos && !visited[node] { visited[node] = true; heap.push((topo_pos, node)); @@ -2088,7 +2099,7 @@ impl<'a> DagFaultAnalyzer<'a> { } } - self.record_at_node_generic(node, prop, detector_idx, recorder, false); + self.record_at_node_generic(node, prop, request.detector_idx, recorder, false); if matches!(gate.gate_type, GateType::PZ | GateType::QAlloc) { let pz_topo = self.propagator.topo_position(node); @@ -2109,7 +2120,7 @@ impl<'a> DagFaultAnalyzer<'a> { } apply_gate(prop, gate, Direction::Backward); - self.record_at_node_generic(node, prop, detector_idx, recorder, true); + self.record_at_node_generic(node, prop, request.detector_idx, recorder, true); let node_topo_pos = self.propagator.topo_position(node); for (j, q) in gate.qubits.iter().enumerate() { @@ -2281,20 +2292,21 @@ impl<'a> DagFaultAnalyzer<'a> { sorted.sort_by_key(|&i| self.propagator.topo_position(measurements[i].0)); // Latest measurement: Phase 1 + Phase 2 with capture - let latest = *sorted.last().unwrap(); + let Some(&latest) = sorted.last() else { + return recorder; + }; let (l_node, l_qubit, l_basis) = measurements[latest]; let mut prop = PauliProp::new(); - let _pz_topo = self.propagate_phase1( - l_node, - l_qubit, - l_basis, - latest, - &mut recorder, - &mut work, - &mut prop, - ); + let latest_request = Phase1Request { + meas_node: l_node, + meas_qubit: l_qubit, + basis: l_basis, + detector_idx: latest, + }; + let _pz_topo = + self.propagate_phase1(&latest_request, &mut recorder, &mut work, &mut prop); let tail_capture = self.propagate_phase2_capture(latest, &mut recorder, &mut work, &mut prop); @@ -2302,15 +2314,14 @@ impl<'a> DagFaultAnalyzer<'a> { for &det_idx in sorted[..sorted.len() - 1].iter().rev() { let (m_node, m_qubit, m_basis) = measurements[det_idx]; - let pz_topo_i = self.propagate_phase1( - m_node, - m_qubit, - m_basis, - det_idx, - &mut recorder, - &mut work, - &mut prop, - ); + let request = Phase1Request { + meas_node: m_node, + meas_qubit: m_qubit, + basis: m_basis, + detector_idx: det_idx, + }; + let pz_topo_i = + self.propagate_phase1(&request, &mut recorder, &mut work, &mut prop); // Replay cached node sequence with correct Pauli state if let Some(pz_pos) = pz_topo_i { diff --git a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs index 5acbbdd38..54c90b492 100644 --- a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs +++ b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs @@ -32,10 +32,20 @@ struct FaultEntry { detector_bits: BTreeSet, /// Observable/logical effect as a sorted set. logical_bits: BTreeSet, - /// Odds-space weight: absolute_probability / no_fault_probability. + /// Odds-space weight: `absolute_probability / no_fault_probability`. odds_weight: f64, } +#[derive(Clone, Copy)] +struct SearchState<'a> { + start_entry: usize, + needed: &'a BTreeSet, + used_locations: &'a BTreeSet, + logical_parity: &'a BTreeSet, + odds_product: f64, + depth: usize, +} + /// Result of decoding a single syndrome. #[derive(Clone, Debug)] pub struct DecodeResult { @@ -57,12 +67,13 @@ pub struct TargetedLookupDecoder { max_faults: usize, base_prob: f64, entries: Vec, - /// Index: detector_bits -> list of entry indices. + /// Index: `detector_bits` -> list of entry indices. by_detector: HashMap, Vec>, } impl TargetedLookupDecoder { /// Build a decoder from a fault catalog. + #[must_use] pub fn new(catalog: &FaultCatalog) -> Self { let base_prob: f64 = catalog .locations @@ -104,18 +115,21 @@ impl TargetedLookupDecoder { } /// Set the maximum number of simultaneous fault locations to consider. + #[must_use] pub fn max_faults(mut self, max_faults: usize) -> Self { self.max_faults = max_faults; self } - /// The all-no-fault probability: product of (1 - p_i) for all locations. + /// The all-no-fault probability: product of `(1 - p_i)` for all locations. + #[must_use] pub fn base_probability(&self) -> f64 { self.base_prob } - /// Decode a syndrome: find all explanations up to max_faults and accumulate + /// Decode a syndrome: find all explanations up to `max_faults` and accumulate /// odds-space weights by logical class. + #[must_use] pub fn decode(&self, syndrome: &[usize]) -> DecodeResult { let target: BTreeSet = syndrome.iter().copied().collect(); let mut logical_weights: BTreeMap, f64> = BTreeMap::new(); @@ -126,13 +140,13 @@ impl TargetedLookupDecoder { } // k=1: direct lookup - if self.max_faults >= 1 { - if let Some(indices) = self.by_detector.get(&target) { - for &i in indices { - let e = &self.entries[i]; - let logical: Vec = e.logical_bits.iter().copied().collect(); - *logical_weights.entry(logical).or_default() += e.odds_weight; - } + if self.max_faults >= 1 + && let Some(indices) = self.by_detector.get(&target) + { + for &i in indices { + let e = &self.entries[i]; + let logical: Vec = e.logical_bits.iter().copied().collect(); + *logical_weights.entry(logical).or_default() += e.odds_weight; } } @@ -161,7 +175,8 @@ impl TargetedLookupDecoder { } } - /// k=2 complement lookup: for each entry a, compute needed_b = target XOR a.detectors, + /// k=2 complement lookup: for each entry `a`, compute + /// `needed_b = target XOR a.detectors`, /// then look up entries with that detector effect. fn search_k2(&self, target: &BTreeSet, logical_weights: &mut BTreeMap, f64>) { for (i, a) in self.entries.iter().enumerate() { @@ -191,40 +206,35 @@ impl TargetedLookupDecoder { target: &BTreeSet, logical_weights: &mut BTreeMap, f64>, ) { - self.search_recursive( - k, - 0, // start_entry - target.clone(), - BTreeSet::new(), // used_locations - BTreeSet::new(), // logical_parity - 1.0, // odds_product - 0, // depth - logical_weights, - ); + let used_locations = BTreeSet::new(); + let logical_parity = BTreeSet::new(); + let state = SearchState { + start_entry: 0, + needed: target, + used_locations: &used_locations, + logical_parity: &logical_parity, + odds_product: 1.0, + depth: 0, + }; + self.search_recursive(k, state, logical_weights); } - #[allow(clippy::too_many_arguments)] fn search_recursive( &self, k: usize, - start_entry: usize, - needed: BTreeSet, - used_locations: BTreeSet, - logical_parity: BTreeSet, - odds_product: f64, - depth: usize, + state: SearchState<'_>, logical_weights: &mut BTreeMap, f64>, ) { - if depth == k { - if needed.is_empty() { - let logical_vec: Vec = logical_parity.into_iter().collect(); - *logical_weights.entry(logical_vec).or_default() += odds_product; + if state.depth == k { + if state.needed.is_empty() { + let logical_vec: Vec = state.logical_parity.iter().copied().collect(); + *logical_weights.entry(logical_vec).or_default() += state.odds_product; } return; } - let remaining = k - depth; - for i in start_entry..self.entries.len() { + let remaining = k - state.depth; + for i in state.start_entry..self.entries.len() { // Check if enough entries remain if self.entries.len() - i < remaining { break; @@ -233,27 +243,26 @@ impl TargetedLookupDecoder { let entry = &self.entries[i]; // Skip if this location is already used - if used_locations.contains(&entry.location_index) { + if state.used_locations.contains(&entry.location_index) { continue; } - let new_needed = xor_sets(&needed, &entry.detector_bits); - let new_logical = xor_sets(&logical_parity, &entry.logical_bits); - let new_odds = odds_product * entry.odds_weight; + let new_needed = xor_sets(state.needed, &entry.detector_bits); + let new_logical = xor_sets(state.logical_parity, &entry.logical_bits); + let new_odds = state.odds_product * entry.odds_weight; - let mut new_used = used_locations.clone(); + let mut new_used = state.used_locations.clone(); new_used.insert(entry.location_index); - self.search_recursive( - k, - i + 1, - new_needed, - new_used, - new_logical, - new_odds, - depth + 1, - logical_weights, - ); + let next_state = SearchState { + start_entry: i + 1, + needed: &new_needed, + used_locations: &new_used, + logical_parity: &new_logical, + odds_product: new_odds, + depth: state.depth + 1, + }; + self.search_recursive(k, next_state, logical_weights); } } } diff --git a/crates/pecos-qec/tests/fault_enumeration_example.rs b/crates/pecos-qec/tests/fault_enumeration_example.rs index b25d2b751..d615d9d42 100644 --- a/crates/pecos-qec/tests/fault_enumeration_example.rs +++ b/crates/pecos-qec/tests/fault_enumeration_example.rs @@ -380,7 +380,7 @@ fn repetition_code_ml_decoder() { println!(" Max weight: {}", decoder.max_weight()); // Build sampler for testing - let sampler = DemSampler::from_circuit(&dag, noise).unwrap(); + let sampler = DemSampler::from_circuit(&dag, &noise).unwrap(); // Sample and decode let mut rng = rand::rngs::SmallRng::seed_from_u64(42); @@ -722,7 +722,7 @@ fn code_422_ml_decoder() { println!(" Observables: {}", decoder.num_observables()); // Build sampler - let sampler = DemSampler::from_circuit(&dag, noise).unwrap(); + let sampler = DemSampler::from_circuit(&dag, &noise).unwrap(); // Sample and decode let mut rng = rand::rngs::SmallRng::seed_from_u64(42); diff --git a/crates/pecos-quantum/src/pass.rs b/crates/pecos-quantum/src/pass.rs index 4bb771957..5e9814b1d 100644 --- a/crates/pecos-quantum/src/pass.rs +++ b/crates/pecos-quantum/src/pass.rs @@ -111,10 +111,10 @@ pub fn compact_ticks(circuit: &mut TickCircuit) { CompactTicks.apply_tick(circuit); } -/// Assign MeasId to measurement gates that don't have them. +/// Assign `MeasId` to measurement gates that don't have them. /// -/// Walks the circuit in tick order and assigns sequential MeasIds -/// to any MZ/MeasureFree gate with empty `meas_ids`. Existing MeasIds +/// Walks the circuit in tick order and assigns sequential `MeasId`s +/// to any MZ/MeasureFree gate with empty `meas_ids`. Existing `MeasId`s /// are preserved. New IDs continue from the circuit's current counter. pub fn assign_missing_meas_ids(circuit: &mut TickCircuit) { AssignMissingMeasIds.apply_tick(circuit); @@ -1191,7 +1191,7 @@ impl CircuitPass for CompactTicks { /// New IDs continue from the circuit's current measurement counter. /// /// Use this on circuits from external sources (QIS trace, Stim import) -/// that don't assign MeasId during construction. +/// that don't assign `MeasId` during construction. pub struct AssignMissingMeasIds; impl CircuitPass for AssignMissingMeasIds { @@ -1201,7 +1201,7 @@ impl CircuitPass for AssignMissingMeasIds { for gate in tick.gates_mut() { let is_measurement = matches!(gate.gate_type, GateType::MZ | GateType::MeasureFree); if is_measurement && gate.meas_ids.is_empty() { - for _ in gate.qubits.iter() { + for _ in &gate.qubits { gate.meas_ids.push(pecos_core::MeasId(next_id)); next_id += 1; } diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index 2858bd12b..fd7648778 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -2197,18 +2197,18 @@ impl From<&TickCircuit> for DagCircuit { .map(|(chunk_idx, qs)| { // For measurement gates, distribute MeasId values // to the split gates (one per qubit). - let mr = if !gate.meas_ids.is_empty() { + let mr = if gate.meas_ids.is_empty() { + GateMeasIds::new() + } else { let start = chunk_idx * chunk_size; gate.meas_ids .get(start..start + chunk_size) - .map(|s| GateMeasIds::from_iter(s.iter().copied())) + .map(|s| s.iter().copied().collect::()) .unwrap_or_default() - } else { - GateMeasIds::new() }; Gate { gate_type: gate.gate_type, - qubits: GateQubits::from_iter(qs.iter().copied()), + qubits: qs.iter().copied().collect::(), angles: gate.angles.clone(), params: gate.params.clone(), meas_ids: mr, diff --git a/crates/pecos-simulators/src/pauli_prop.rs b/crates/pecos-simulators/src/pauli_prop.rs index b370d85d1..0a24fef5f 100644 --- a/crates/pecos-simulators/src/pauli_prop.rs +++ b/crates/pecos-simulators/src/pauli_prop.rs @@ -601,7 +601,7 @@ impl CliffordGateable for PauliProp { /// Applies the adjoint square root of Z gate. /// - /// Ignoring global phase, SZ and SZdg have the same binary Pauli action: + /// Ignoring global phase, `SZ` and `SZdg` have the same binary Pauli action: /// X <-> Y, Z -> Z. #[inline] fn szdg(&mut self, qubits: &[QubitId]) -> &mut Self { @@ -668,7 +668,7 @@ impl CliffordGateable for PauliProp { /// Applies the adjoint square root of X gate. /// - /// Ignoring global phase, SX and SXdg have the same binary Pauli action. + /// Ignoring global phase, `SX` and `SXdg` have the same binary Pauli action. #[inline] fn sxdg(&mut self, qubits: &[QubitId]) -> &mut Self { for &q in qubits { @@ -696,7 +696,7 @@ impl CliffordGateable for PauliProp { /// Applies the adjoint square root of Y gate. /// - /// Ignoring global phase, SY and SYdg have the same binary Pauli action. + /// Ignoring global phase, `SY` and `SYdg` have the same binary Pauli action. #[inline] fn sydg(&mut self, qubits: &[QubitId]) -> &mut Self { for &q in qubits { @@ -793,7 +793,7 @@ impl CliffordGateable for PauliProp { /// Applies the adjoint square root of XX gate. /// - /// Ignoring global phase, SXX and SXXdg have the same binary Pauli action. + /// Ignoring global phase, `SXX` and `SXXdg` have the same binary Pauli action. #[inline] fn sxxdg(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { for &(q1, q2) in pairs { @@ -828,7 +828,7 @@ impl CliffordGateable for PauliProp { /// Applies the adjoint square root of YY gate. /// - /// Ignoring global phase, SYY and SYYdg have the same binary Pauli action. + /// Ignoring global phase, `SYY` and `SYYdg` have the same binary Pauli action. #[inline] fn syydg(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { for &(q1, q2) in pairs { @@ -863,7 +863,7 @@ impl CliffordGateable for PauliProp { /// Applies the adjoint square root of ZZ gate. /// - /// Ignoring global phase, SZZ and SZZdg have the same binary Pauli action. + /// Ignoring global phase, `SZZ` and `SZZdg` have the same binary Pauli action. #[inline] fn szzdg(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { for &(q1, q2) in pairs { diff --git a/crates/pecos-simulators/src/state_vec_soa.rs b/crates/pecos-simulators/src/state_vec_soa.rs index 0676a86f4..9b6b885fd 100644 --- a/crates/pecos-simulators/src/state_vec_soa.rs +++ b/crates/pecos-simulators/src/state_vec_soa.rs @@ -4504,10 +4504,8 @@ where let scaled_im: [f64; 4] = (norm_vec * im).into(); self.real[i + j..i + j + 4].copy_from_slice(&scaled_re); self.imag[i + j..i + j + 4].copy_from_slice(&scaled_im); - self.real[i + step + j..i + step + j + 4] - .copy_from_slice(&[0.0; 4]); - self.imag[i + step + j..i + step + j + 4] - .copy_from_slice(&[0.0; 4]); + self.real[i + step + j..i + step + j + 4].copy_from_slice(&[0.0; 4]); + self.imag[i + step + j..i + step + j + 4].copy_from_slice(&[0.0; 4]); j += 4; } } else { diff --git a/crates/pecos-simulators/src/state_vector_test_utils.rs b/crates/pecos-simulators/src/state_vector_test_utils.rs index 914cb6536..8eb17590c 100644 --- a/crates/pecos-simulators/src/state_vector_test_utils.rs +++ b/crates/pecos-simulators/src/state_vector_test_utils.rs @@ -928,9 +928,11 @@ pub fn verify_mid_circuit_reset(sim: &mut S) { s.cx(&qid2(0, 1)); let r2 = s.mz(&qid(1)); assert_eq!( - r1[0].outcome, r2[0].outcome, + r1[0].outcome, + r2[0].outcome, "seed {seed}: mid-circuit reset: r1={}, r2={} — should match", - r1[0].outcome as u8, r2[0].outcome as u8 + u8::from(r1[0].outcome), + u8::from(r2[0].outcome) ); } } diff --git a/crates/pecos-simulators/src/symbolic_sparse_stab.rs b/crates/pecos-simulators/src/symbolic_sparse_stab.rs index b76028ecc..36d50d0c5 100644 --- a/crates/pecos-simulators/src/symbolic_sparse_stab.rs +++ b/crates/pecos-simulators/src/symbolic_sparse_stab.rs @@ -26,9 +26,9 @@ //! - `measurement_indices`: Set of measurement indices whose outcomes XOR together //! - `flip`: Boolean indicating whether to flip the result (from unitary gate phases) +use crate::QuantumSimulator; use crate::sign_algebra::{SignAlgebra, SymbolicSign}; use crate::symbolic_gens::SymbolicGensVecSet; -use crate::QuantumSimulator; use core::mem; use pecos_core::{BitSet, Set, VecSet}; @@ -614,7 +614,7 @@ impl SymbolicSparseStabVecSet { /// Project qubit onto +Z eigenstate without recording a measurement. /// /// Same Gaussian elimination as `nondeterministic_meas` but does not - /// record a measurement or increment the counter. The resulting Z_q + /// record a measurement or increment the counter. The resulting `Z` on `q` /// stabilizer gets an empty sign (eigenvalue +1). fn pz_nondeterministic(&mut self, q: usize) { let mut anticom_stabs_col = self.stabs.col_x[q].clone(); diff --git a/crates/pecos-uf-decoder/examples/profile_decode.rs b/crates/pecos-uf-decoder/examples/profile_decode.rs index 5726a8ff1..c5077367a 100644 --- a/crates/pecos-uf-decoder/examples/profile_decode.rs +++ b/crates/pecos-uf-decoder/examples/profile_decode.rs @@ -18,11 +18,7 @@ fn profile_decoder(name: &str, dem: &str, num_shots: usize) { // Generate random syndromes let mut rng = fastrand::Rng::with_seed(42); let syndromes: Vec> = (0..num_shots) - .map(|_| { - (0..num_det) - .map(|_| u8::from(rng.f64() < 0.05)) - .collect() - }) + .map(|_| (0..num_det).map(|_| u8::from(rng.f64() < 0.05)).collect()) .collect(); // Warm up @@ -54,11 +50,7 @@ fn profile_phases(name: &str, dem: &str, num_shots: usize) { let mut rng = fastrand::Rng::with_seed(42); let syndromes: Vec> = (0..num_shots) - .map(|_| { - (0..num_det) - .map(|_| u8::from(rng.f64() < 0.05)) - .collect() - }) + .map(|_| (0..num_det).map(|_| u8::from(rng.f64() < 0.05)).collect()) .collect(); // Phase 1: measure reset + syndrome loading only @@ -133,11 +125,7 @@ fn main() { let mut rng = fastrand::Rng::with_seed(42); let syndromes: Vec> = (0..num_shots) - .map(|_| { - (0..num_det) - .map(|_| u8::from(rng.f64() < 0.05)) - .collect() - }) + .map(|_| (0..num_det).map(|_| u8::from(rng.f64() < 0.05)).collect()) .collect(); let t0 = Instant::now(); diff --git a/crates/pecos-uf-decoder/src/bp_uf.rs b/crates/pecos-uf-decoder/src/bp_uf.rs index a224ea6fe..0a293ce40 100644 --- a/crates/pecos-uf-decoder/src/bp_uf.rs +++ b/crates/pecos-uf-decoder/src/bp_uf.rs @@ -24,6 +24,7 @@ use crate::decoder::{UfDecoder, UfDecoderConfig}; use crate::mini_bp::{self, BpGraph}; +use pecos_decoder_core::correlated_decoder::MatchingDecoder; use pecos_decoder_core::dem::{DemCheckMatrix, DemMatchingGraph}; use pecos_decoder_core::errors::DecoderError; @@ -161,7 +162,11 @@ impl BpUfDecoder { // then find the matching edge connecting those detectors. let mut mechanism_to_edge = vec![None; dcm.num_mechanisms]; - for m in 0..dcm.num_mechanisms { + for (m, mechanism_edge) in mechanism_to_edge + .iter_mut() + .enumerate() + .take(dcm.num_mechanisms) + { let mut detectors: Vec = Vec::new(); for d in 0..dcm.num_detectors { if dcm.check_matrix[[d, m]] != 0 { @@ -176,7 +181,7 @@ impl BpUfDecoder { let d0 = detectors[0]; for (idx, edge) in graph.edges.iter().enumerate() { if edge.node1 == d0 && edge.node2.is_none() { - mechanism_to_edge[m] = Some(idx); + *mechanism_edge = Some(idx); break; } } @@ -188,7 +193,7 @@ impl BpUfDecoder { if (edge.node1 == d0 && edge.node2 == Some(d1)) || (edge.node1 == d1 && edge.node2 == Some(d0)) { - mechanism_to_edge[m] = Some(idx); + *mechanism_edge = Some(idx); break; } } @@ -251,7 +256,11 @@ impl BpUfDecoder { // Map BP mechanisms (non-decomposed) → matching graph edges (decomposed). let mut mechanism_to_edge = vec![None; bp_dcm.num_mechanisms]; - for m in 0..bp_dcm.num_mechanisms { + for (m, mechanism_edge) in mechanism_to_edge + .iter_mut() + .enumerate() + .take(bp_dcm.num_mechanisms) + { let mut detectors: Vec = Vec::new(); for d in 0..bp_dcm.num_detectors { if bp_dcm.check_matrix[[d, m]] != 0 { @@ -263,7 +272,7 @@ impl BpUfDecoder { let d0 = detectors[0]; for (idx, edge) in match_graph.edges.iter().enumerate() { if edge.node1 == d0 && edge.node2.is_none() { - mechanism_to_edge[m] = Some(idx); + *mechanism_edge = Some(idx); break; } } @@ -274,7 +283,7 @@ impl BpUfDecoder { if (edge.node1 == d0 && edge.node2 == Some(d1)) || (edge.node1 == d1 && edge.node2 == Some(d0)) { - mechanism_to_edge[m] = Some(idx); + *mechanism_edge = Some(idx); break; } } @@ -532,7 +541,6 @@ impl pecos_decoder_core::ObservableDecoder for BpUfDecoder { } // Stage 3: Use UF with BP-adjusted weights. - use pecos_decoder_core::correlated_decoder::MatchingDecoder; let (mask, matched_edges) = self .uf .decode_with_weights(syndrome, &self.adjusted_weights)?; @@ -602,9 +610,7 @@ error(0.1) D1 // Random syndromes shouldn't panic let mut rng = fastrand::Rng::with_seed(42); for _ in 0..100 { - let syn: Vec = (0..24) - .map(|_| u8::from(rng.f64() < 0.05)) - .collect(); + let syn: Vec = (0..24).map(|_| u8::from(rng.f64() < 0.05)).collect(); let _ = dec.decode_to_observables(&syn).unwrap(); } } diff --git a/crates/pecos-uf-decoder/src/decoder.rs b/crates/pecos-uf-decoder/src/decoder.rs index 1b96f4ed9..366789c0a 100644 --- a/crates/pecos-uf-decoder/src/decoder.rs +++ b/crates/pecos-uf-decoder/src/decoder.rs @@ -27,6 +27,7 @@ use pecos_decoder_core::dem::DemMatchingGraph; use pecos_decoder_core::errors::DecoderError; +use pecos_decoder_core::correlated_decoder::MatchingDecoder; use std::cmp::Reverse; use std::collections::BinaryHeap; @@ -342,9 +343,10 @@ impl UfDecoder { pub fn decode_syndrome(&mut self, syndrome: &[u8]) -> u64 { // Try cluster-detection predecoder (if enabled). if self.config.predecoder - && let Some(obs) = self.predecode_clusters(syndrome) { - return obs; - } + && let Some(obs) = self.predecode_clusters(syndrome) + { + return obs; + } // Full decoder path for complex syndromes. self.reset(); @@ -460,8 +462,8 @@ impl UfDecoder { } else if comp_size[root] == 2 { // Find the other defect in this component. let mut ni = None; - for dj in (di + 1)..n { - if component[dj] == root { + for (dj, &candidate_root) in component.iter().enumerate().take(n).skip(di + 1) { + if candidate_root == root { ni = Some(dj); break; } @@ -977,6 +979,10 @@ impl UfDecoder { /// Decode with full UF (no predecoder) and return matched edges. /// Used by windowed decoder which needs complete edge tracking. + /// + /// # Errors + /// + /// Returns `DecoderError` if decoding fails. pub fn decode_full_matching( &mut self, syndrome: &[u8], @@ -1077,9 +1083,10 @@ impl pecos_decoder_core::correlated_decoder::MatchingDecoder for UfDecoder { // Cluster predecoder (if enabled). Skipped in windowed mode // because windowed decoding needs complete edge tracking. if self.config.predecoder - && let Some(obs) = self.predecode_clusters(syndrome) { - return Ok((obs, Vec::new())); - } + && let Some(obs) = self.predecode_clusters(syndrome) + { + return Ok((obs, Vec::new())); + } // Full decode path. self.reset(); @@ -1169,7 +1176,6 @@ impl pecos_decoder_core::erasure::ObservableErasureDecoder for UfDecoder { } } - use pecos_decoder_core::correlated_decoder::MatchingDecoder; let (obs, _) = self.decode_with_weights(syndrome, &modified_weights)?; Ok(obs) } diff --git a/crates/pecos-uf-decoder/src/mini_bp.rs b/crates/pecos-uf-decoder/src/mini_bp.rs index 325d5a7cf..fd6510c36 100644 --- a/crates/pecos-uf-decoder/src/mini_bp.rs +++ b/crates/pecos-uf-decoder/src/mini_bp.rs @@ -83,11 +83,11 @@ impl BpGraph { let mut temp_var: Vec> = vec![Vec::new(); num_vars]; let mut msg_idx: u32 = 0; - for c in 0..num_checks { - for v in 0..num_vars { + for (c, check_entries) in temp_check.iter_mut().enumerate().take(num_checks) { + for (v, var_entries) in temp_var.iter_mut().enumerate().take(num_vars) { if dcm.check_matrix[[c, v]] != 0 { - temp_check[c].push((v as u32, msg_idx)); - temp_var[v].push((c as u32, msg_idx)); + check_entries.push((v as u32, msg_idx)); + var_entries.push((c as u32, msg_idx)); msg_idx += 1; } } @@ -133,6 +133,7 @@ impl BpGraph { /// - `serial`: if true, use serial schedule (better convergence, slower) /// - `c_to_v`, `v_to_c`: reusable message buffers (must be `graph.total_edges` long) /// - `posterior`: output buffer (must be `graph.num_vars` long) +#[allow(clippy::too_many_arguments)] // Hot-path helper takes reusable buffers explicitly. pub fn min_sum_bp_into( graph: &BpGraph, syndrome: &[u8], @@ -177,26 +178,26 @@ pub fn min_sum_bp_into( num_iterations }; - for _outer in 0..outer_iterations { + for outer in 0..outer_iterations { // Re-initialize v→c with current EWA posteriors as priors. - if _outer > 0 { - for v in 0..num_vars { + if outer > 0 { + for (v, &prior) in ewa_posterior.iter().enumerate().take(num_vars) { for &(_c, idx) in graph.var_entries(v) { - v_to_c[idx as usize] = ewa_posterior[v]; + v_to_c[idx as usize] = prior; } } c_to_v.fill(0.0); } for iter in 0..inner_iterations { - for c in 0..num_checks { + for (c, &syndrome_sign) in syn_sign.iter().enumerate().take(num_checks) { let entries = graph.check_entries(c); if entries.len() < 2 { continue; } // Check-to-variable (normalized min-sum). - let mut total_sign = syn_sign[c]; + let mut total_sign = syndrome_sign; let mut min1 = f64::INFINITY; let mut min2 = f64::INFINITY; let mut min1_pos = usize::MAX; @@ -244,12 +245,12 @@ pub fn min_sum_bp_into( if !serial { // Flooding: batch update all variables after all checks. - for v in 0..num_vars { + for (v, &prior) in graph.prior_llr.iter().enumerate().take(num_vars) { let gamma = damp; let entries = graph.var_entries(v); let total: f64 = entries.iter().map(|&(_c, idx)| c_to_v[idx as usize]).sum(); for &(_c, idx) in entries { - let new_msg = graph.prior_llr[v] + total - c_to_v[idx as usize]; + let new_msg = prior + total - c_to_v[idx as usize]; v_to_c[idx as usize] = (1.0 - gamma) * new_msg + gamma * v_to_c[idx as usize]; } @@ -257,19 +258,19 @@ pub fn min_sum_bp_into( } // EWA: blend current iteration's posterior into the running average. - let w = if iter == 0 && _outer == 0 { + let w = if iter == 0 && outer == 0 { 1.0 } else { ewa_weight }; - for v in 0..num_vars { + for (v, ewa) in ewa_posterior.iter_mut().enumerate().take(num_vars) { let cur_posterior = graph.prior_llr[v] + graph .var_entries(v) .iter() .map(|&(_c, idx)| c_to_v[idx as usize]) .sum::(); - ewa_posterior[v] = (1.0 - w) * ewa_posterior[v] + w * cur_posterior; + *ewa = (1.0 - w) * *ewa + w * cur_posterior; } } // end inner iteration loop } // end outer EWAInit loop @@ -279,7 +280,7 @@ pub fn min_sum_bp_into( posterior.extend_from_slice(&ewa_posterior); // Also include final iteration's raw posterior for variables where // EWA and raw agree in sign (reinforcement). - for v in 0..num_vars { + for (v, post) in posterior.iter_mut().enumerate().take(num_vars) { let raw = graph.prior_llr[v] + graph .var_entries(v) @@ -287,10 +288,9 @@ pub fn min_sum_bp_into( .map(|&(_c, idx)| c_to_v[idx as usize]) .sum::(); // If EWA and raw agree, use the one with larger magnitude (more confident). - if (posterior[v] > 0.0) == (raw > 0.0) - && raw.abs() > posterior[v].abs() { - posterior[v] = raw; - } + if (*post > 0.0) == (raw > 0.0) && raw.abs() > post.abs() { + *post = raw; + } // If they disagree, keep EWA (it's more stable). } } @@ -358,11 +358,7 @@ pub fn matching_graph_bp( .map(|n| { if n < syndrome.len() && syndrome[n] != 0 { -1.0 - } else if n == boundary { - 1.0 - } - // boundary always even - else { + } else { 1.0 } }) diff --git a/crates/pecos-uf-decoder/src/windowed.rs b/crates/pecos-uf-decoder/src/windowed.rs index 5aa130dd4..b8b97141d 100644 --- a/crates/pecos-uf-decoder/src/windowed.rs +++ b/crates/pecos-uf-decoder/src/windowed.rs @@ -29,6 +29,7 @@ use pecos_decoder_core::ObservableDecoder; use pecos_decoder_core::correlated_decoder::EdgeTrackingDecoder; use pecos_decoder_core::dem::DemMatchingGraph; use pecos_decoder_core::errors::DecoderError; +use std::fmt::Write as _; /// Configuration for the windowed decoder. #[derive(Debug, Clone, Copy, Default)] @@ -366,6 +367,10 @@ impl SandwichWindowedDecoder { /// /// Requires `D: Send` for thread safety. Phase-1 windows run on rayon's /// thread pool; Phase-2 residual runs sequentially after. + /// + /// # Errors + /// + /// Returns `DecoderError` if any window decoder fails. pub fn decode_parallel(&mut self, syndrome: &[u8]) -> Result where D: Send, @@ -530,11 +535,7 @@ fn parse_dem_params( } let num_rounds = (max_time + 1.0) as usize; - let num_stab = if num_rounds > 0 { - num_detectors / num_rounds - } else { - num_detectors - }; + let num_stab = num_detectors.checked_div(num_rounds).unwrap_or(num_detectors); let d_est = ((num_stab as f64).sqrt().ceil() as usize).max(3); let step_size = if config.step_size > 0 { config.step_size @@ -579,9 +580,8 @@ fn extract_window_dem( } if trimmed.starts_with("error(") { - let close = match trimmed.find(')') { - Some(p) => p, - None => continue, + let Some(close) = trimmed.find(')') else { + continue; }; let prob_str = &trimmed[6..close]; let rest = &trimmed[close + 1..]; @@ -606,12 +606,14 @@ fn extract_window_dem( for tok in seg { if let Some(d_str) = tok.strip_prefix('D') { if let Ok(d) = d_str.parse::() - && d < num_det && in_window[d] { - seg_any_in = true; - if let Some(local) = global_to_local[d] { - seg_dets.push(format!("D{local}")); - } + && d < num_det + && in_window[d] + { + seg_any_in = true; + if let Some(local) = global_to_local[d] { + seg_dets.push(format!("D{local}")); } + } } else if tok.starts_with('L') { seg_obs.push((*tok).to_string()); } @@ -628,19 +630,21 @@ fn extract_window_dem( } if !remapped_segments.is_empty() { - out.push_str(&format!("error({prob_str}) ")); + let _ = write!(out, "error({prob_str}) "); out.push_str(&remapped_segments.join(" ^ ")); out.push('\n'); } } else if trimmed.starts_with("detector(") && let Some(d_start) = trimmed.rfind('D') - && let Ok(d) = trimmed[d_start + 1..].trim().parse::() - && d < num_det && in_window[d] - && let Some(local) = global_to_local[d] { - let coords_end = trimmed.find(')').unwrap_or(trimmed.len()); - out.push_str(&trimmed[..=coords_end]); - out.push_str(&format!(" D{local}\n")); - } + && let Ok(d) = trimmed[d_start + 1..].trim().parse::() + && d < num_det + && in_window[d] + && let Some(local) = global_to_local[d] + { + let coords_end = trimmed.find(')').unwrap_or(trimmed.len()); + out.push_str(&trimmed[..=coords_end]); + let _ = writeln!(out, " D{local}"); + } } (local_to_global, out) diff --git a/exp/pecos-eeg/examples/profile_heisenberg.rs b/exp/pecos-eeg/examples/profile_heisenberg.rs index 3f7a6f786..5a3c4adca 100644 --- a/exp/pecos-eeg/examples/profile_heisenberg.rs +++ b/exp/pecos-eeg/examples/profile_heisenberg.rs @@ -14,7 +14,7 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), angles: GateAngles::new(), params: GateParams::new(), - meas_ids: pecos_core::GateMeasIds::new(), + meas_ids: pecos_core::GateMeasIds::new(), } } @@ -23,7 +23,9 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { fn build_weight4_circuit(num_rounds: usize) -> Vec { // Data: 0,1,2,3. Ancilla: 4. let mut gates = Vec::new(); - for q in 0..5 { gates.push(gate(GateType::PZ, &[q])); } + for q in 0..5 { + gates.push(gate(GateType::PZ, &[q])); + } for round in 0..num_rounds { gates.push(gate(GateType::H, &[4])); gates.push(gate(GateType::CX, &[4, 0])); @@ -36,7 +38,9 @@ fn build_weight4_circuit(num_rounds: usize) -> Vec { gates.push(gate(GateType::PZ, &[4])); } } - for q in 0..4 { gates.push(gate(GateType::MZ, &[q])); } + for q in 0..4 { + gates.push(gate(GateType::MZ, &[q])); + } gates } @@ -60,10 +64,14 @@ fn main() { let init_gates: Vec = (0..5) .map(|q| pecos_eeg::expand::make_gate(GateType::PZ, &[q])) .collect(); - let stab = pecos_eeg::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); + let stab = + pecos_eeg::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); - eprintln!("Weight-4 X-check, {num_rounds} rounds, {} expanded qubits, {} detectors", - expanded.num_qubits, detectors.len()); + eprintln!( + "Weight-4 X-check, {num_rounds} rounds, {} expanded qubits, {} detectors", + expanded.num_qubits, + detectors.len() + ); // Run 20 iterations to get enough samples for perf let iters = 20; @@ -71,12 +79,21 @@ fn main() { for _ in 0..iters { for det in &detectors { let _p = pecos_eeg::heisenberg::heisenberg_detection_probability( - &expanded.gates, det, &noise, &stab, 0.0, + &expanded.gates, + det, + &noise, + &stab, + 0.0, ); } } let total = t.elapsed(); let per_det = total.as_secs_f64() * 1000.0 / (detectors.len() * iters) as f64; - eprintln!("{iters} iterations x {} dets = {} calls in {:.2}s ({:.2}ms/det)", - detectors.len(), detectors.len() * iters, total.as_secs_f64(), per_det); + eprintln!( + "{iters} iterations x {} dets = {} calls in {:.2}s ({:.2}ms/det)", + detectors.len(), + detectors.len() * iters, + total.as_secs_f64(), + per_det + ); } diff --git a/exp/pecos-eeg/src/builder.rs b/exp/pecos-eeg/src/builder.rs index c9cf24957..6a71314d9 100644 --- a/exp/pecos-eeg/src/builder.rs +++ b/exp/pecos-eeg/src/builder.rs @@ -60,9 +60,7 @@ impl<'a> EegDemBuilder<'a> { let gates: Vec = self.tc.iter_gates().cloned().collect(); let expanded = expand::expand_circuit(&gates); let result = circuit::analyze_expanded(&expanded.gates, &self.noise); - let (detectors, observables) = build_detectors( - self.tc, &expanded, - ); + let (detectors, observables) = build_detectors(self.tc, &expanded); // Compute stabilizer group from the EXPANDED circuit (pre-readout). // This includes auxiliary qubits, so beta function checks happen @@ -72,8 +70,11 @@ impl<'a> EegDemBuilder<'a> { let stab_group = StabilizerGroup::from_circuit(&expanded_pre_readout, expanded.num_qubits); dem_mapping::build_dem_configured( - &result.generators, &detectors, &observables, - Some(&stab_group), &self.config, + &result.generators, + &detectors, + &observables, + Some(&stab_group), + &self.config, ) } @@ -92,14 +93,23 @@ impl<'a> EegDemBuilder<'a> { let expanded_pre = exclude_final_mz(&expanded.gates); let stab_group = StabilizerGroup::from_circuit(&expanded_pre, expanded.num_qubits); let entries = dem_mapping::build_dem_configured( - &result.generators, &detectors, &observables, - Some(&stab_group), &self.config, + &result.generators, + &detectors, + &observables, + Some(&stab_group), + &self.config, ); - let h_count = result.generators.iter() - .filter(|g| g.eeg_type == crate::eeg::EegType::H).count(); - let s_count = result.generators.iter() - .filter(|g| g.eeg_type == crate::eeg::EegType::S).count(); + let h_count = result + .generators + .iter() + .filter(|g| g.eeg_type == crate::eeg::EegType::H) + .count(); + let s_count = result + .generators + .iter() + .filter(|g| g.eeg_type == crate::eeg::EegType::S) + .count(); EegSummary { num_original_gates: gates.len(), @@ -134,9 +144,9 @@ pub struct EegSummary { /// The expanded circuit ends with deferred MZ(aux) gates. Stripping them /// gives the pre-readout expanded state for stabilizer group computation. fn exclude_final_mz(gates: &[pecos_core::Gate]) -> Vec { - let last_non_mz = gates.iter().rposition(|g| { - g.gate_type != pecos_core::gate_type::GateType::MZ - }); + let last_non_mz = gates + .iter() + .rposition(|g| g.gate_type != pecos_core::gate_type::GateType::MZ); match last_non_mz { Some(idx) => gates[..=idx].to_vec(), None => Vec::new(), @@ -163,7 +173,9 @@ fn build_detectors( for annotation in tc.annotations() { match &annotation.kind { - AnnotationKind::Detector { measurement_nodes, .. } => { + AnnotationKind::Detector { + measurement_nodes, .. + } => { // measurement_nodes are gate indices in the ORIGINAL circuit. // We need to map these to measurement record indices, then // to auxiliary qubits in the expanded circuit. @@ -176,16 +188,22 @@ fn build_detectors( // k-th qubit measured across all MZ gates in order. Each // measurement_node is a gate index — we find which measurement // records that gate produced. - let bitmask = measurement_nodes_to_aux_bitmask( - measurement_nodes, tc, expanded, num_meas, - ); - detectors.push(Detector { id: detectors.len(), stabilizer: bitmask }); + let bitmask = + measurement_nodes_to_aux_bitmask(measurement_nodes, tc, expanded, num_meas); + detectors.push(Detector { + id: detectors.len(), + stabilizer: bitmask, + }); } - AnnotationKind::Observable { measurement_nodes, .. } => { - let bitmask = measurement_nodes_to_aux_bitmask( - measurement_nodes, tc, expanded, num_meas, - ); - observables.push(Observable { id: observables.len(), pauli: bitmask }); + AnnotationKind::Observable { + measurement_nodes, .. + } => { + let bitmask = + measurement_nodes_to_aux_bitmask(measurement_nodes, tc, expanded, num_meas); + observables.push(Observable { + id: observables.len(), + pauli: bitmask, + }); } AnnotationKind::Operator => {} } @@ -268,19 +286,22 @@ mod tests { let result = circuit::analyze_expanded(&expanded.gates, &noise); let expanded_pre = exclude_final_mz(&expanded.gates); - let stab_group = StabilizerGroup::from_circuit( - &expanded_pre, expanded.num_qubits, - ); + let stab_group = StabilizerGroup::from_circuit(&expanded_pre, expanded.num_qubits); let (detectors, observables) = build_detectors(&tc, &expanded); let manual_entries = dem_mapping::build_dem_with_stabilizers( - &result.generators, &detectors, &observables, + &result.generators, + &detectors, + &observables, Some(&stab_group), ); // Same number of entries - assert_eq!(builder_entries.len(), manual_entries.len(), - "Builder and manual should produce same number of DEM entries"); + assert_eq!( + builder_entries.len(), + manual_entries.len(), + "Builder and manual should produce same number of DEM entries" + ); // Same probabilities (order may differ, so sort) let mut bp: Vec = builder_entries.iter().map(|e| e.probability).collect(); @@ -288,8 +309,10 @@ mod tests { bp.sort_by(|a, b| a.partial_cmp(b).unwrap()); mp.sort_by(|a, b| a.partial_cmp(b).unwrap()); for (b, m) in bp.iter().zip(mp.iter()) { - assert!((b - m).abs() < 1e-15, - "Probability mismatch: builder={b}, manual={m}"); + assert!( + (b - m).abs() < 1e-15, + "Probability mismatch: builder={b}, manual={m}" + ); } } @@ -305,8 +328,10 @@ mod tests { .noise(NoiseModel::depolarizing(0.01)) .build(); - assert!(entries.is_empty(), - "No annotations → no detectors → no DEM entries"); + assert!( + entries.is_empty(), + "No annotations → no detectors → no DEM entries" + ); } #[test] @@ -336,8 +361,10 @@ mod tests { .noise(NoiseModel::depolarizing(0.01)) .build(); - assert!(!entries.is_empty(), - "Circuit with detector annotation should produce DEM entries"); + assert!( + !entries.is_empty(), + "Circuit with detector annotation should produce DEM entries" + ); for e in &entries { assert!(e.probability > 0.0); assert!(e.probability < 0.5); @@ -356,8 +383,14 @@ mod tests { .noise(NoiseModel::depolarizing(0.01).with_idle_rz(0.05)) .summary(); - assert!(summary.num_h_generators > 0, "Should have H generators from idle RZ"); - assert!(summary.num_s_generators > 0, "Should have S generators from depolarizing"); + assert!( + summary.num_h_generators > 0, + "Should have H generators from idle RZ" + ); + assert!( + summary.num_s_generators > 0, + "Should have S generators from depolarizing" + ); assert_eq!(summary.num_expanded_qubits, 6, "3 original + 3 aux"); } } diff --git a/exp/pecos-eeg/src/circuit.rs b/exp/pecos-eeg/src/circuit.rs index e4bb1dbec..79d2b3de7 100644 --- a/exp/pecos-eeg/src/circuit.rs +++ b/exp/pecos-eeg/src/circuit.rs @@ -11,9 +11,13 @@ use crate::Bm; use crate::eeg::EegType; -use pecos_core::gate_type::GateType; -use pecos_core::pauli::pauli_bitmask::*; use pecos_core::Gate; +use pecos_core::gate_type::GateType; +use pecos_core::pauli::pauli_bitmask::{ + BitmaskStorage, Conjugated, conjugate_cx, conjugate_cy, conjugate_cz, conjugate_h, + conjugate_swap, conjugate_sx, conjugate_sxdg, conjugate_sy, conjugate_sydg, conjugate_sz, + conjugate_szdg, conjugate_x, conjugate_y, conjugate_z, +}; /// Noise model parameters. #[derive(Clone, Debug)] @@ -33,12 +37,24 @@ pub struct NoiseModel { impl NoiseModel { #[must_use] pub fn coherent_only(idle_rz: f64) -> Self { - Self { idle_rz, p1: 0.0, p2: 0.0, p_meas: 0.0, p_prep: 0.0 } + Self { + idle_rz, + p1: 0.0, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + } } #[must_use] pub fn depolarizing(p: f64) -> Self { - Self { idle_rz: 0.0, p1: p, p2: p, p_meas: p, p_prep: p } + Self { + idle_rz: 0.0, + p1: p, + p2: p, + p_meas: p, + p_prep: p, + } } #[must_use] @@ -107,7 +123,10 @@ impl EegAnalysisResult { /// /// Expansion gates (QAlloc, expansion CX, expansion PZ) are skipped /// for noise injection. -pub fn analyze_with_noise(gates: &[Gate], noise: &dyn crate::noise::NoiseSpec) -> EegAnalysisResult { +pub fn analyze_with_noise( + gates: &[Gate], + noise: &dyn crate::noise::NoiseSpec, +) -> EegAnalysisResult { let mut generators = Vec::new(); let mut num_measurements = 0; @@ -133,7 +152,7 @@ pub fn analyze_with_noise(gates: &[Gate], noise: &dyn crate::noise::NoiseSpec) - for (i, gate) in gates.iter().enumerate() { let remaining = &gates[i + 1..]; - let qubits: Vec = gate.qubits.iter().map(|q| q.index()).collect(); + let qubits: Vec = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); // Skip expansion gates (virtual, not physical) let is_expansion = expansion_cx_indices.contains(&i) @@ -149,22 +168,35 @@ pub fn analyze_with_noise(gates: &[Gate], noise: &dyn crate::noise::NoiseSpec) - EegType::H => { let (pl, coeff) = propagate_h(inj.label, inj.rate, remaining); generators.push(PropagatedEeg { - eeg_type: EegType::H, label: pl, label2: None, coeff, - source: Some(NoiseSource { gate_index: i, qubit: qubits.first().copied().unwrap_or(0) }), + eeg_type: EegType::H, + label: pl, + label2: None, + coeff, + source: Some(NoiseSource { + gate_index: i, + qubit: qubits.first().copied().unwrap_or(0), + }), }); } EegType::S => { let (pl, _) = propagate_s(inj.label, remaining); generators.push(PropagatedEeg { - eeg_type: EegType::S, label: pl, label2: None, coeff: inj.rate, + eeg_type: EegType::S, + label: pl, + label2: None, + coeff: inj.rate, source: None, }); } EegType::C | EegType::A => { if let Some(label2) = inj.label2 { - let (l1, l2, coeff) = propagate_ca(inj.label, label2, inj.rate, remaining); + let (l1, l2, coeff) = + propagate_ca(inj.label, label2, inj.rate, remaining); generators.push(PropagatedEeg { - eeg_type: inj.eeg_type, label: l1, label2: Some(l2), coeff, + eeg_type: inj.eeg_type, + label: l1, + label2: Some(l2), + coeff, source: None, }); } @@ -174,16 +206,22 @@ pub fn analyze_with_noise(gates: &[Gate], noise: &dyn crate::noise::NoiseSpec) - } // Handle explicit RZ gates (from the circuit, not noise model) - if gate.gate_type == GateType::RZ { - if let Some(&angle) = gate.angles.first() { - for &q in &qubits { - let label = Bm::z(q); - let (pl, coeff) = propagate_h(label, angle.to_radians() / 2.0, remaining); - generators.push(PropagatedEeg { - eeg_type: EegType::H, label: pl, label2: None, coeff, - source: Some(NoiseSource { gate_index: i, qubit: q }), - }); - } + if gate.gate_type == GateType::RZ + && let Some(&angle) = gate.angles.first() + { + for &q in &qubits { + let label = Bm::z(q); + let (pl, coeff) = propagate_h(label, angle.to_radians() / 2.0, remaining); + generators.push(PropagatedEeg { + eeg_type: EegType::H, + label: pl, + label2: None, + coeff, + source: Some(NoiseSource { + gate_index: i, + qubit: q, + }), + }); } } @@ -193,12 +231,16 @@ pub fn analyze_with_noise(gates: &[Gate], noise: &dyn crate::noise::NoiseSpec) - } } - EegAnalysisResult { generators, num_measurements } + EegAnalysisResult { + generators, + num_measurements, + } } /// Analyze the expanded circuit with the legacy NoiseModel. /// /// Delegates to `analyze_with_noise` using a `UniformNoise` specification. +#[must_use] pub fn analyze_expanded(gates: &[Gate], noise: &NoiseModel) -> EegAnalysisResult { let uniform = crate::noise::UniformNoise { idle_rz: noise.idle_rz, @@ -225,7 +267,9 @@ fn propagate_h(mut label: Bm, mut coeff: f64, remaining: &[Gate]) -> (Bm, f64) { _ => { if let Some(r) = conjugate_by_gate(&label, gate) { label = r.label; - if r.sign_negative { coeff = -coeff; } + if r.sign_negative { + coeff = -coeff; + } } } } @@ -256,13 +300,19 @@ fn propagate_ca( let mut sign = false; if let Some(r) = conjugate_by_gate(&label1, gate) { label1 = r.label; - if r.sign_negative { sign = !sign; } + if r.sign_negative { + sign = !sign; + } } if let Some(r) = conjugate_by_gate(&label2, gate) { label2 = r.label; - if r.sign_negative { sign = !sign; } + if r.sign_negative { + sign = !sign; + } + } + if sign { + coeff = -coeff; } - if sign { coeff = -coeff; } } } } @@ -291,7 +341,9 @@ fn propagate_s(mut label: Bm, remaining: &[Gate]) -> (Bm, f64) { } fn conjugate_by_gate(label: &Bm, gate: &Gate) -> Option>> { - if gate.qubits.is_empty() { return None; } + if gate.qubits.is_empty() { + return None; + } let q0 = || gate.qubits[0].index(); let q1 = || gate.qubits[1].index(); match gate.gate_type { @@ -316,7 +368,7 @@ fn conjugate_by_gate(label: &Bm, gate: &Gate) -> Option Gate { Gate { @@ -332,57 +384,66 @@ mod tests { fn test_rz_rate_is_half_theta() { // Idle RZ(0.1) after CX: rate should be 0.05 (theta/2) // because RZ(theta) = exp(-i*theta*Z/2) → H_Z with rate theta/2 - let gates = vec![ - gate(GateType::CX, &[0, 1]), - ]; + let gates = vec![gate(GateType::CX, &[0, 1])]; let noise = NoiseModel::coherent_only(0.1); let result = analyze_expanded(&gates, &noise); - let h_gens: Vec<_> = result.generators.iter() + let h_gens: Vec<_> = result + .generators + .iter() .filter(|g| g.eeg_type == EegType::H) .collect(); assert_eq!(h_gens.len(), 2); for g in &h_gens { - assert!((g.coeff.abs() - 0.05).abs() < 1e-10, - "Rate should be 0.05 (theta/2), got {}", g.coeff); + assert!( + (g.coeff.abs() - 0.05).abs() < 1e-10, + "Rate should be 0.05 (theta/2), got {}", + g.coeff + ); } } #[test] fn test_h_propagation_through_hadamard() { // H_Z after H gate: Z → X, sign positive - let gates = vec![ - gate(GateType::CX, &[0, 1]), - gate(GateType::H, &[0]), - ]; + let gates = vec![gate(GateType::CX, &[0, 1]), gate(GateType::H, &[0])]; let noise = NoiseModel::coherent_only(0.1); let result = analyze_expanded(&gates, &noise); - let q0_gen = result.generators.iter() + let q0_gen = result + .generators + .iter() .find(|g| g.eeg_type == EegType::H && g.label.has_x(0)) .expect("Should have H_X on qubit 0"); - assert!((q0_gen.coeff - 0.05).abs() < 1e-10, "H: Z→X, rate=theta/2=0.05"); + assert!( + (q0_gen.coeff - 0.05).abs() < 1e-10, + "H: Z→X, rate=theta/2=0.05" + ); } #[test] fn test_sx_propagation() { // SX on qubit 1 after CX: Z1 → -Y1 (sign flip) - let gates = vec![ - gate(GateType::CX, &[0, 1]), - gate(GateType::SX, &[1]), - ]; + let gates = vec![gate(GateType::CX, &[0, 1]), gate(GateType::SX, &[1])]; let noise = NoiseModel::coherent_only(0.1); let result = analyze_expanded(&gates, &noise); // H_Z(1) propagated through SX(1): Z→-Y, coeff flips sign - let q1_gen = result.generators.iter() + let q1_gen = result + .generators + .iter() .find(|g| g.eeg_type == EegType::H && g.label.has_x(1) && g.label.has_z(1)) .expect("Should have H_Y on qubit 1 after SX"); - assert!((q1_gen.coeff + 0.05).abs() < 1e-10, - "SX: Z→-Y, sign flips: expected -0.05, got {}", q1_gen.coeff); + assert!( + (q1_gen.coeff + 0.05).abs() < 1e-10, + "SX: Z→-Y, sign flips: expected -0.05, got {}", + q1_gen.coeff + ); // H_Z(0) should be unaffected by SX on qubit 1 - let q0_gen = result.generators.iter() + let q0_gen = result + .generators + .iter() .find(|g| g.eeg_type == EegType::H && g.label == Bm::z(0)) .expect("Should still have H_Z on qubit 0"); assert!((q0_gen.coeff - 0.05).abs() < 1e-10); @@ -391,17 +452,15 @@ mod tests { #[test] fn test_cy_propagation() { // CY after CX: Z on target propagates like CX (Z_t → Z_c Z_t) - let gates = vec![ - gate(GateType::CX, &[0, 1]), - gate(GateType::CY, &[0, 1]), - ]; + let gates = vec![gate(GateType::CX, &[0, 1]), gate(GateType::CY, &[0, 1])]; let noise = NoiseModel::coherent_only(0.1); let result = analyze_expanded(&gates, &noise); // H_Z(1) from CX, propagated through CY: Z_t → Z_c Z_t - let zz_gen = result.generators.iter() - .find(|g| g.eeg_type == EegType::H - && g.label == Bm::z(0).multiply(&Bm::z(1))) + let zz_gen = result + .generators + .iter() + .find(|g| g.eeg_type == EegType::H && g.label == Bm::z(0).multiply(&Bm::z(1))) .expect("Should have Z0Z1 after CY propagation of Z1"); assert!((zz_gen.coeff.abs() - 0.05).abs() < 1e-10); } @@ -409,19 +468,21 @@ mod tests { #[test] fn test_sy_propagation() { // SY: X→-Z, Z→X. So H_Z through SY gives H_X with no sign flip - let gates = vec![ - gate(GateType::CX, &[0, 1]), - gate(GateType::SY, &[1]), - ]; + let gates = vec![gate(GateType::CX, &[0, 1]), gate(GateType::SY, &[1])]; let noise = NoiseModel::coherent_only(0.1); let result = analyze_expanded(&gates, &noise); // H_Z(1) through SY(1): Z→X, no sign flip - let q1_gen = result.generators.iter() + let q1_gen = result + .generators + .iter() .find(|g| g.eeg_type == EegType::H && g.label == Bm::x(1)) .expect("Should have H_X on qubit 1 after SY"); - assert!((q1_gen.coeff - 0.05).abs() < 1e-10, - "SY: Z→X, no sign: expected 0.05, got {}", q1_gen.coeff); + assert!( + (q1_gen.coeff - 0.05).abs() < 1e-10, + "SY: Z→X, no sign: expected 0.05, got {}", + q1_gen.coeff + ); } #[test] @@ -435,24 +496,27 @@ mod tests { let result = analyze_expanded(&gates, &noise); // H_Z(1) should be cleared by PZ(1) - let q1_gens: Vec<_> = result.generators.iter() + let q1_gens: Vec<_> = result + .generators + .iter() .filter(|g| g.eeg_type == EegType::H && (g.label.has_x(1) || g.label.has_z(1))) .collect(); - assert!(q1_gens.is_empty(), - "PZ should clear all error components on qubit 1"); + assert!( + q1_gens.is_empty(), + "PZ should clear all error components on qubit 1" + ); // H_Z(0) should survive (PZ on qubit 1 doesn't touch qubit 0) - let q0_gen = result.generators.iter() + let q0_gen = result + .generators + .iter() .find(|g| g.eeg_type == EegType::H && g.label == Bm::z(0)); assert!(q0_gen.is_some(), "H_Z(0) should survive PZ(1)"); } #[test] fn test_no_noise_no_generators() { - let gates = vec![ - gate(GateType::CX, &[0, 1]), - gate(GateType::H, &[0]), - ]; + let gates = vec![gate(GateType::CX, &[0, 1]), gate(GateType::H, &[0])]; let noise = NoiseModel::coherent_only(0.0); let result = analyze_expanded(&gates, &noise); assert!(result.generators.is_empty()); @@ -462,15 +526,30 @@ mod tests { fn test_depol_1q_injects_three_paulis() { // Single-qubit depolarizing on H gate produces S_X, S_Y, S_Z let gates = vec![gate(GateType::H, &[0])]; - let noise = NoiseModel { idle_rz: 0.0, p1: 0.03, p2: 0.0, p_meas: 0.0, p_prep: 0.0 }; + let noise = NoiseModel { + idle_rz: 0.0, + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }; let result = analyze_expanded(&gates, &noise); - let s_gens: Vec<_> = result.generators.iter() + let s_gens: Vec<_> = result + .generators + .iter() .filter(|g| g.eeg_type == EegType::S) .collect(); - assert_eq!(s_gens.len(), 3, "1q depolarizing should inject 3 S generators"); + assert_eq!( + s_gens.len(), + 3, + "1q depolarizing should inject 3 S generators" + ); for g in &s_gens { - assert!((g.coeff + 0.01).abs() < 1e-10, "Rate should be -p/3 = -0.01"); + assert!( + (g.coeff + 0.01).abs() < 1e-10, + "Rate should be -p/3 = -0.01" + ); } } @@ -478,15 +557,30 @@ mod tests { fn test_depol_2q_injects_fifteen_paulis() { // Two-qubit depolarizing on CX: 15 S generators (3 single + 3 single + 9 tensor) let gates = vec![gate(GateType::CX, &[0, 1])]; - let noise = NoiseModel { idle_rz: 0.0, p1: 0.0, p2: 0.15, p_meas: 0.0, p_prep: 0.0 }; + let noise = NoiseModel { + idle_rz: 0.0, + p1: 0.0, + p2: 0.15, + p_meas: 0.0, + p_prep: 0.0, + }; let result = analyze_expanded(&gates, &noise); - let s_gens: Vec<_> = result.generators.iter() + let s_gens: Vec<_> = result + .generators + .iter() .filter(|g| g.eeg_type == EegType::S) .collect(); - assert_eq!(s_gens.len(), 15, "2q depolarizing should inject 15 S generators"); + assert_eq!( + s_gens.len(), + 15, + "2q depolarizing should inject 15 S generators" + ); for g in &s_gens { - assert!((g.coeff + 0.01).abs() < 1e-10, "Rate should be -p/15 = -0.01"); + assert!( + (g.coeff + 0.01).abs() < 1e-10, + "Rate should be -p/15 = -0.01" + ); } } @@ -494,10 +588,18 @@ mod tests { fn test_meas_noise_injects_sx() { // Measurement error produces S_X on the measured qubit let gates = vec![gate(GateType::MZ, &[0])]; - let noise = NoiseModel { idle_rz: 0.0, p1: 0.0, p2: 0.0, p_meas: 0.05, p_prep: 0.0 }; + let noise = NoiseModel { + idle_rz: 0.0, + p1: 0.0, + p2: 0.0, + p_meas: 0.05, + p_prep: 0.0, + }; let result = analyze_expanded(&gates, &noise); - let s_gens: Vec<_> = result.generators.iter() + let s_gens: Vec<_> = result + .generators + .iter() .filter(|g| g.eeg_type == EegType::S) .collect(); assert_eq!(s_gens.len(), 1); @@ -509,10 +611,18 @@ mod tests { fn test_prep_noise_injects_sx() { // Preparation error: S_X after PZ let gates = vec![gate(GateType::PZ, &[0])]; - let noise = NoiseModel { idle_rz: 0.0, p1: 0.0, p2: 0.0, p_meas: 0.0, p_prep: 0.03 }; + let noise = NoiseModel { + idle_rz: 0.0, + p1: 0.0, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.03, + }; let result = analyze_expanded(&gates, &noise); - let s_gens: Vec<_> = result.generators.iter() + let s_gens: Vec<_> = result + .generators + .iter() .filter(|g| g.eeg_type == EegType::S) .collect(); assert_eq!(s_gens.len(), 1); @@ -530,34 +640,48 @@ mod tests { gate(GateType::H, &[1]), gate(GateType::CX, &[1, 0]), gate(GateType::MZ, &[1]), - gate(GateType::PZ, &[1]), // original reset + gate(GateType::PZ, &[1]), // original reset gate(GateType::H, &[1]), gate(GateType::CX, &[1, 0]), - gate(GateType::MZ, &[1]), // last round + gate(GateType::MZ, &[1]), // last round gate(GateType::MZ, &[0]), ]; let expanded = crate::expand::expand_circuit(&original_gates); // Count PZ gates in expanded circuit (originals + expansion projections) - let all_pz: Vec<_> = expanded.gates.iter() + let all_pz: Vec<_> = expanded + .gates + .iter() .filter(|g| g.gate_type == GateType::PZ) .collect(); // With prep noise: count S generators from prep - let noise = NoiseModel { idle_rz: 0.0, p1: 0.0, p2: 0.0, p_meas: 0.0, p_prep: 0.1 }; + let noise = NoiseModel { + idle_rz: 0.0, + p1: 0.0, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.1, + }; let result = analyze_expanded(&expanded.gates, &noise); - let prep_gens: Vec<_> = result.generators.iter() + let prep_gens: Vec<_> = result + .generators + .iter() .filter(|g| g.eeg_type == EegType::S) .collect(); // Original PZ gates: PZ(0) init, PZ(1) init, PZ(1) reset = 3 PZ with noise // Expansion PZ: should NOT inject noise // Each original PZ injects 1 S generator (S_X) - assert_eq!(prep_gens.len(), 3, + assert_eq!( + prep_gens.len(), + 3, "Only original PZ should inject prep noise, not expansion PZ. \ Got {} S generators, total PZ gates in expanded: {}", - prep_gens.len(), all_pz.len()); + prep_gens.len(), + all_pz.len() + ); } #[test] @@ -577,11 +701,16 @@ mod tests { let noise = NoiseModel::coherent_only(0.1); let result = analyze_expanded(&expanded.gates, &noise); - let h_gens: Vec<_> = result.generators.iter() + let h_gens: Vec<_> = result + .generators + .iter() .filter(|g| g.eeg_type == EegType::H) .collect(); // Only 2 H generators from the original CX (one per qubit) - assert_eq!(h_gens.len(), 2, - "Only original CX should get noise, not expansion CX gates"); + assert_eq!( + h_gens.len(), + 2, + "Only original CX should get noise, not expansion CX gates" + ); } } diff --git a/exp/pecos-eeg/src/coherent_dem.rs b/exp/pecos-eeg/src/coherent_dem.rs index 2749a8d62..a3bf21ed5 100644 --- a/exp/pecos-eeg/src/coherent_dem.rs +++ b/exp/pecos-eeg/src/coherent_dem.rs @@ -22,14 +22,16 @@ use crate::Bm; use crate::dem_mapping::{DecomposableDemEntry, DemEntry, DemEvent, Detector, Observable}; -use crate::heisenberg::{SparsePauli, sparse_conjugate}; use crate::eeg::EegType; +use crate::heisenberg::{SparsePauli, sparse_conjugate}; use crate::noise::NoiseSpec; use pecos_core::Gate; use pecos_core::pauli::pauli_bitmask::BitmaskStorage; use smallvec::SmallVec; use std::collections::BTreeMap; +type FittedEventKey = (SmallVec<[usize; 4]>, SmallVec<[usize; 2]>); + /// A noise contribution at a specific gate. struct NoiseContribution { /// Effective Pauli label after backward propagation. @@ -63,15 +65,19 @@ pub fn build_coherent_dem( if gate_idx < expansion_gates.len() && expansion_gates[gate_idx] { continue; } - let qubits: SmallVec<[usize; 4]> = gate.qubits.iter().map(|q| q.index()).collect(); + let qubits: SmallVec<[usize; 4]> = + gate.qubits.iter().map(pecos_core::QubitId::index).collect(); let injections = noise.noise_after_gate(gate_idx, gate.gate_type, &qubits); for inj in injections { - noise_sources.push((gate_idx, NoiseContribution { - label: inj.label.clone(), - eeg_type: inj.eeg_type, - value: inj.rate, - })); + noise_sources.push(( + gate_idx, + NoiseContribution { + label: inj.label.clone(), + eeg_type: inj.eeg_type, + value: inj.rate, + }, + )); } } @@ -185,14 +191,20 @@ pub fn build_coherent_dem( for ((event, _label), total_h) in &h_groups { let prob = total_h.sin().powi(2); if prob > 1e-15 { - entries.push(DemEntry { event: event.clone(), probability: prob }); + entries.push(DemEntry { + event: event.clone(), + probability: prob, + }); } } for ((event, _label), total_s) in &s_groups { let prob = (1.0 - (2.0 * total_s).exp()) / 2.0; if prob.abs() > 1e-15 { - entries.push(DemEntry { event: event.clone(), probability: prob.abs() }); + entries.push(DemEntry { + event: event.clone(), + probability: prob.abs(), + }); } } @@ -220,15 +232,19 @@ pub fn build_coherent_dem_decomposable( if gate_idx < expansion_gates.len() && expansion_gates[gate_idx] { continue; } - let qubits: SmallVec<[usize; 4]> = gate.qubits.iter().map(|q| q.index()).collect(); + let qubits: SmallVec<[usize; 4]> = + gate.qubits.iter().map(pecos_core::QubitId::index).collect(); let injections = noise.noise_after_gate(gate_idx, gate.gate_type, &qubits); for inj in injections { - noise_sources.push((gate_idx, NoiseContribution { - label: inj.label.clone(), - eeg_type: inj.eeg_type, - value: inj.rate, - })); + noise_sources.push(( + gate_idx, + NoiseContribution { + label: inj.label.clone(), + eeg_type: inj.eeg_type, + value: inj.rate, + }, + )); } } @@ -243,18 +259,20 @@ pub fn build_coherent_dem_decomposable( let mut noise_z_obs_sets: Vec> = vec![SmallVec::new(); num_noise]; // Precompute X-only and Z-only labels for each noise source - let noise_x_labels: Vec = noise_sources.iter().map(|(_, c)| { - let mut x_only = Bm::default(); - x_only.x_bits = c.label.x_bits.clone(); - // z_bits stays zero - x_only - }).collect(); - let noise_z_labels: Vec = noise_sources.iter().map(|(_, c)| { - let mut z_only = Bm::default(); - z_only.z_bits = c.label.z_bits.clone(); - // x_bits stays zero - z_only - }).collect(); + let noise_x_labels: Vec = noise_sources + .iter() + .map(|(_, c)| Bm { + x_bits: c.label.x_bits.clone(), + ..Default::default() + }) + .collect(); + let noise_z_labels: Vec = noise_sources + .iter() + .map(|(_, c)| Bm { + z_bits: c.label.z_bits.clone(), + ..Default::default() + }) + .collect(); // Build gate -> noise source index map let mut gate_to_noise: BTreeMap> = BTreeMap::new(); @@ -302,9 +320,15 @@ pub fn build_coherent_dem_decomposable( for det in detectors { let (hits_full, hits_x, hits_z) = backward_classify_xz(&det.stabilizer); for ns_idx in 0..num_noise { - if hits_full[ns_idx] { noise_det_sets[ns_idx].push(det.id); } - if hits_x[ns_idx] { noise_x_det_sets[ns_idx].push(det.id); } - if hits_z[ns_idx] { noise_z_det_sets[ns_idx].push(det.id); } + if hits_full[ns_idx] { + noise_det_sets[ns_idx].push(det.id); + } + if hits_x[ns_idx] { + noise_x_det_sets[ns_idx].push(det.id); + } + if hits_z[ns_idx] { + noise_z_det_sets[ns_idx].push(det.id); + } } } @@ -312,9 +336,15 @@ pub fn build_coherent_dem_decomposable( for obs in observables { let (hits_full, hits_x, hits_z) = backward_classify_xz(&obs.pauli); for ns_idx in 0..num_noise { - if hits_full[ns_idx] { noise_obs_sets[ns_idx].push(obs.id); } - if hits_x[ns_idx] { noise_x_obs_sets[ns_idx].push(obs.id); } - if hits_z[ns_idx] { noise_z_obs_sets[ns_idx].push(obs.id); } + if hits_full[ns_idx] { + noise_obs_sets[ns_idx].push(obs.id); + } + if hits_x[ns_idx] { + noise_x_obs_sets[ns_idx].push(obs.id); + } + if hits_z[ns_idx] { + noise_z_obs_sets[ns_idx].push(obs.id); + } } } @@ -349,7 +379,8 @@ pub fn build_coherent_dem_decomposable( EegType::S => &mut s_groups, _ => continue, }; - groups.entry(key) + groups + .entry(key) .and_modify(|(val, _, _)| *val += contrib.value) .or_insert((contrib.value, x_event, z_event)); } @@ -389,14 +420,18 @@ pub fn build_coherent_dem_decomposable( merge_decomposable_dem_entries(entries) } -fn merge_decomposable_dem_entries(mut entries: Vec) -> Vec { +fn merge_decomposable_dem_entries( + mut entries: Vec, +) -> Vec { if entries.len() <= 1 { return entries; } // Sort by combined event entries.sort_by(|a, b| { - a.event.detectors.cmp(&b.event.detectors) + a.event + .detectors + .cmp(&b.event.detectors) .then(a.event.observables.cmp(&b.event.observables)) }); @@ -495,12 +530,13 @@ pub fn build_coherent_dem_exact( // Loss = sum_d (marginal_d - target_d)^2 // + sum_pairs (pairwise_ij - target_ij)^2 let pairs: Vec<((usize, usize), f64)> = heisenberg_pairwise - .map(|p| p.to_vec()) + .map(<[((usize, usize), f64)]>::to_vec) .unwrap_or_default(); let has_pairwise = !pairs.is_empty(); // Initialize x from q: x = logit(q / 0.499) - let mut x: Vec = q.iter() + let mut x: Vec = q + .iter() .map(|&qi| { let s = (qi / 0.499).clamp(1e-10, 1.0 - 1e-10); (s / (1.0 - s)).ln() @@ -528,7 +564,9 @@ pub fn build_coherent_dem_exact( loss += residual * residual; let mut full_prod = 1.0; - for &m in &det_to_mechs[d] { full_prod *= 1.0 - 2.0 * q_local[m]; } + for &m in &det_to_mechs[d] { + full_prod *= 1.0 - 2.0 * q_local[m]; + } for &m in &det_to_mechs[d] { let factor = 1.0 - 2.0 * q_local[m]; if factor.abs() > 1e-30 { @@ -542,13 +580,17 @@ pub fn build_coherent_dem_exact( let full_prods: Vec = (0..num_dets) .map(|d| { let mut p = 1.0; - for &m in &det_to_mechs[d] { p *= 1.0 - 2.0 * q_local[m]; } + for &m in &det_to_mechs[d] { + p *= 1.0 - 2.0 * q_local[m]; + } p }) .collect(); for &((di, dj), target_p) in &pairs { - if di >= num_dets || dj >= num_dets || target_p < 1e-10 { continue; } + if di >= num_dets || dj >= num_dets || target_p < 1e-10 { + continue; + } let prod_i = full_prods[di]; let prod_j = full_prods[dj]; @@ -558,7 +600,9 @@ pub fn build_coherent_dem_exact( } let prod_xor = if prod_both.abs() > 1e-30 { prod_i * prod_j / (prod_both * prod_both) - } else { 0.0 }; + } else { + 0.0 + }; let current_p = (1.0 - prod_i - prod_j + prod_xor) / 4.0; let residual = current_p - target_p; @@ -590,7 +634,9 @@ pub fn build_coherent_dem_exact( } // Chain rule: grad_x = grad_q * dq/dx - let grad_x: Vec = grad_q.iter().zip(dq_dx.iter()) + let grad_x: Vec = grad_q + .iter() + .zip(dq_dx.iter()) .map(|(&gq, &dx)| gq * dx) .collect(); @@ -606,7 +652,9 @@ pub fn build_coherent_dem_exact( let (mut loss, mut grad) = compute_loss_grad(&x); for _iter in 0..500 { - if loss < 1e-14 { break; } + if loss < 1e-14 { + break; + } // L-BFGS direction: H_k * grad let mut direction = grad.clone(); @@ -616,39 +664,57 @@ pub fn build_coherent_dem_exact( let mut alpha = vec![0.0; hist_len]; for i in (0..hist_len).rev() { alpha[i] = rho_hist[i] * dot(&s_hist[i], &direction); - for j in 0..n_mech { direction[j] -= alpha[i] * y_hist[i][j]; } + for j in 0..n_mech { + direction[j] -= alpha[i] * y_hist[i][j]; + } } // Scale by gamma = s'y / y'y from most recent pair if let (Some(s), Some(y)) = (s_hist.last(), y_hist.last()) { let yy = dot(y, y); if yy > 1e-30 { let gamma = dot(s, y) / yy; - for d in &mut direction { *d *= gamma; } + for d in &mut direction { + *d *= gamma; + } } } for i in 0..hist_len { let beta = rho_hist[i] * dot(&y_hist[i], &direction); - for j in 0..n_mech { direction[j] += (alpha[i] - beta) * s_hist[i][j]; } + for j in 0..n_mech { + direction[j] += (alpha[i] - beta) * s_hist[i][j]; + } } // Negate for descent direction - for d in &mut direction { *d = -*d; } + for d in &mut direction { + *d = -*d; + } // Backtracking line search (Armijo condition) let dg = dot(&grad, &direction); - if dg >= 0.0 { break; } // not a descent direction + if dg >= 0.0 { + break; + } // not a descent direction let mut step = 1.0; let c1 = 1e-4; - let mut x_new: Vec = x.iter().zip(direction.iter()) - .map(|(&xi, &di)| xi + step * di).collect(); + let mut x_new: Vec = x + .iter() + .zip(direction.iter()) + .map(|(&xi, &di)| xi + step * di) + .collect(); let (mut loss_new, mut grad_new) = compute_loss_grad(&x_new); for _ in 0..20 { - if loss_new <= loss + c1 * step * dg { break; } + if loss_new <= loss + c1 * step * dg { + break; + } step *= 0.5; - x_new = x.iter().zip(direction.iter()) - .map(|(&xi, &di)| xi + step * di).collect(); + x_new = x + .iter() + .zip(direction.iter()) + .map(|(&xi, &di)| xi + step * di) + .collect(); let (ln, gn) = compute_loss_grad(&x_new); loss_new = ln; grad_new = gn; @@ -656,7 +722,11 @@ pub fn build_coherent_dem_exact( // Update L-BFGS history let s_k: Vec = x_new.iter().zip(x.iter()).map(|(&a, &b)| a - b).collect(); - let y_k: Vec = grad_new.iter().zip(grad.iter()).map(|(&a, &b)| a - b).collect(); + let y_k: Vec = grad_new + .iter() + .zip(grad.iter()) + .map(|(&a, &b)| a - b) + .collect(); let sy = dot(&s_k, &y_k); if sy > 1e-30 { if s_hist.len() >= m_lbfgs { @@ -680,9 +750,14 @@ pub fn build_coherent_dem_exact( } // Build fitted DEM entries - let fitted: Vec = approx.iter().zip(q.iter()) + let fitted: Vec = approx + .iter() + .zip(q.iter()) .filter(|(_, p)| **p > 1e-15) - .map(|(entry, p)| DemEntry { event: entry.event.clone(), probability: *p }) + .map(|(entry, p)| DemEntry { + event: entry.event.clone(), + probability: *p, + }) .collect(); merge_dem_entries(fitted) @@ -702,9 +777,8 @@ pub fn build_coherent_dem_exact_decomposable( heisenberg_pairwise: Option<&[((usize, usize), f64)]>, ) -> Vec { // Get X/Z component structure from decomposable builder - let decomposable = build_coherent_dem_decomposable( - gates, noise, detectors, observables, expansion_gates, - ); + let decomposable = + build_coherent_dem_decomposable(gates, noise, detectors, observables, expansion_gates); if decomposable.is_empty() { return decomposable; @@ -712,32 +786,46 @@ pub fn build_coherent_dem_exact_decomposable( // Get fitted probabilities from exact builder let fitted = build_coherent_dem_exact( - gates, noise, detectors, observables, expansion_gates, - heisenberg_marginals, heisenberg_pairwise, + gates, + noise, + detectors, + observables, + expansion_gates, + heisenberg_marginals, + heisenberg_pairwise, ); // Build lookup: event → fitted probability - let mut prob_lookup: BTreeMap<(SmallVec<[usize; 4]>, SmallVec<[usize; 2]>), f64> = BTreeMap::new(); + let mut prob_lookup: BTreeMap = BTreeMap::new(); for entry in &fitted { prob_lookup.insert( - (entry.event.detectors.clone(), entry.event.observables.clone()), + ( + entry.event.detectors.clone(), + entry.event.observables.clone(), + ), entry.probability, ); } // Combine: X/Z structure from decomposable + fitted probabilities from exact - decomposable.into_iter().filter_map(|mut entry| { - let key = (entry.event.detectors.clone(), entry.event.observables.clone()); - if let Some(&fitted_prob) = prob_lookup.get(&key) { - entry.probability = fitted_prob; - Some(entry) - } else if entry.probability > 1e-15 { - // Keep original probability if no fitted version (edge case) - Some(entry) - } else { - None - } - }).collect() + decomposable + .into_iter() + .filter_map(|mut entry| { + let key = ( + entry.event.detectors.clone(), + entry.event.observables.clone(), + ); + if let Some(&fitted_prob) = prob_lookup.get(&key) { + entry.probability = fitted_prob; + Some(entry) + } else if entry.probability > 1e-15 { + // Keep original probability if no fitted version (edge case) + Some(entry) + } else { + None + } + }) + .collect() } /// Merge DEM entries with the same event via independent combination. diff --git a/exp/pecos-eeg/src/correlation_table.rs b/exp/pecos-eeg/src/correlation_table.rs index 3e9d6e0ac..ed42f237d 100644 --- a/exp/pecos-eeg/src/correlation_table.rs +++ b/exp/pecos-eeg/src/correlation_table.rs @@ -33,7 +33,9 @@ use crate::dem_mapping::{Detector, Observable}; use crate::noise::NoiseSpec; use crate::stabilizer::StabilizerGroup; use pecos_core::Gate; +use rayon::iter::{IntoParallelRefIterator, ParallelIterator}; use std::collections::BTreeMap; +use std::fmt::Write as _; /// Exact k-body correlation table for detectors and observables. /// @@ -57,6 +59,27 @@ pub struct CorrelationTable { pub num_walks: usize, } +/// Inputs for exact correlation table construction. +#[derive(Clone, Copy)] +pub struct CorrelationTableInput<'a> { + /// Circuit gates. + pub gates: &'a [Gate], + /// Noise model used for exact correlation targets. + pub noise: &'a dyn NoiseSpec, + /// Detector definitions. + pub detectors: &'a [Detector], + /// Observable definitions. + pub observables: &'a [Observable], + /// Initial stabilizer group. + pub initial_stab: &'a StabilizerGroup, + /// Number of circuit qubits. + pub num_qubits: usize, + /// Maximum detector/observable correlation order. + pub max_order: usize, + /// Drop probabilities below this threshold. + pub prune_threshold: f64, +} + impl CorrelationTable { /// Build a graphlike DEM string from the correlation table. /// @@ -120,7 +143,7 @@ impl CorrelationTable { let mut targets = format!("D{di} D{dj}"); for o in &obs_list { - targets.push_str(&format!(" L{o}")); + let _ = write!(targets, " L{o}"); } lines.push(format!("error({p_edge:.6e}) {targets}")); } @@ -156,16 +179,19 @@ impl CorrelationTable { /// /// Each entry gives the exact joint detection probability for a subset of /// detectors, including all coherent interference effects. -pub fn compute_correlation_table( - gates: &[Gate], - noise: &dyn NoiseSpec, - detectors: &[Detector], - observables: &[Observable], - initial_stab: &StabilizerGroup, - num_qubits: usize, - max_order: usize, - prune_threshold: f64, -) -> CorrelationTable { +#[must_use] +pub fn compute_correlation_table(input: CorrelationTableInput<'_>) -> CorrelationTable { + let CorrelationTableInput { + gates, + noise, + detectors, + observables, + initial_stab, + num_qubits, + max_order, + prune_threshold, + } = input; + let n = detectors.len(); let n_obs = observables.len(); let has_stochastic = true; // conservative; could check noise params @@ -215,7 +241,6 @@ pub fn compute_correlation_table( } // Run all walks in parallel - use rayon::prelude::*; let walk_results: Vec<(Vec, f64)> = walk_items .par_iter() .map(|(det_ids, product)| { @@ -243,7 +268,11 @@ pub fn compute_correlation_table( // Iterate over all subsets T of {0..k-1} for mask in 0..(1u64 << k) { let subset_size = mask.count_ones() as usize; - let sign = if subset_size % 2 == 0 { 1.0 } else { -1.0 }; + let sign = if subset_size.is_multiple_of(2) { + 1.0 + } else { + -1.0 + }; if subset_size == 0 { // Empty subset: = 1, contribution = (-1)^k * 1 diff --git a/exp/pecos-eeg/src/dem_generator.rs b/exp/pecos-eeg/src/dem_generator.rs index 1b5699231..f36dd7608 100644 --- a/exp/pecos-eeg/src/dem_generator.rs +++ b/exp/pecos-eeg/src/dem_generator.rs @@ -92,7 +92,7 @@ impl DemGenerator for CoherentApprox { } } - fn name(&self) -> &str { + fn name(&self) -> &'static str { "coherent_approx" } } @@ -195,7 +195,7 @@ impl DemGenerator for CoherentExact { } } - fn name(&self) -> &str { + fn name(&self) -> &'static str { "coherent_exact" } } @@ -212,21 +212,12 @@ impl DemGenerator for Perturbative { #[allow(unused_imports)] use crate::circuit::analyze_expanded; #[allow(unused_imports)] - use crate::dem_mapping::{build_dem_configured, build_dem_decomposable, EegConfig}; + use crate::dem_mapping::{EegConfig, build_dem_configured, build_dem_decomposable}; #[allow(unused_imports)] use crate::noise::UniformNoise; - // Forward EEG analysis (placeholder — currently falls back to coherent_dem) - let _noise_model = crate::circuit::NoiseModel { - idle_rz: 0.0, // extracted from noise spec indirectly - p1: 0.0, - p2: 0.0, - p_meas: 0.0, - p_prep: 0.0, - }; // We need to extract params from the NoiseSpec — use a test gate to probe - let probe_noise = noise.noise_after_gate(0, pecos_core::gate_type::GateType::H, &[0]); - let _ = probe_noise; // The forward EEG path needs its own NoiseModel + let _ = noise.noise_after_gate(0, pecos_core::gate_type::GateType::H, &[0]); // For now, use the coherent_dem path as fallback since forward EEG // requires its own NoiseModel type (not the NoiseSpec trait) @@ -254,24 +245,17 @@ impl DemGenerator for Perturbative { } } - fn name(&self) -> &str { + fn name(&self) -> &'static str { "perturbative" } } /// Select a DEM generator by method name. -pub fn select_generator(method: &str, idle_rz: f64) -> Box { +#[must_use] +pub fn select_generator(method: &str, _idle_rz: f64) -> Box { match method { - "auto" => { - if idle_rz.abs() > 1e-15 { - Box::new(CoherentApprox) - } else { - Box::new(CoherentApprox) // same for now; stochastic would be from_circuit - } - } - "coherent" | "coherent_approx" => Box::new(CoherentApprox), "coherent_exact" => Box::new(CoherentExact::default()), "perturbative" => Box::new(Perturbative), - _ => Box::new(CoherentApprox), // default fallback + _ => Box::new(CoherentApprox), // auto/coherent/default fallback } } diff --git a/exp/pecos-eeg/src/dem_mapping.rs b/exp/pecos-eeg/src/dem_mapping.rs index 5e120dc2b..3eb475278 100644 --- a/exp/pecos-eeg/src/dem_mapping.rs +++ b/exp/pecos-eeg/src/dem_mapping.rs @@ -12,10 +12,18 @@ use crate::Bm; use crate::circuit::PropagatedEeg; use crate::eeg::EegType; use crate::stabilizer::StabilizerGroup; -use pecos_core::{Pauli, PauliString}; use pecos_core::pauli::pauli_bitmask::BitmaskStorage; +use pecos_core::{Pauli, PauliString}; use smallvec::SmallVec; use std::collections::BTreeMap; +use std::fmt::Write as _; + +type DetectorSet = SmallVec<[usize; 4]>; +type ObservableSet = SmallVec<[usize; 2]>; +type EventKey = (DetectorSet, ObservableSet); +type XzComponents = (Option, Option); +type GraphlikePieces = Vec; +type DecompMemo = BTreeMap>; /// Controls the H-type probability formula. #[derive(Clone, Copy, Debug, Default, PartialEq, Eq)] @@ -183,7 +191,10 @@ pub fn pauli_string_to_bitmask(ps: &PauliString) -> Bm { match pauli { Pauli::X => bm.x_bits.set_bit(q), Pauli::Z => bm.z_bits.set_bit(q), - Pauli::Y => { bm.x_bits.set_bit(q); bm.z_bits.set_bit(q); } + Pauli::Y => { + bm.x_bits.set_bit(q); + bm.z_bits.set_bit(q); + } Pauli::I => {} } } @@ -204,7 +215,10 @@ fn classify(label: &Bm, detectors: &[Detector], observables: &[Observable]) -> D obs.push(o.id); } } - DemEvent { detectors: dets, observables: obs } + DemEvent { + detectors: dets, + observables: obs, + } } /// Classify with X/Z component decomposition. @@ -224,16 +238,18 @@ fn classify_xz( // Build X-only and Z-only labels let x_only = if has_x { - let mut bm = Bm::default(); - bm.x_bits = label.x_bits.clone(); - Some(bm) + Some(Bm { + x_bits: label.x_bits.clone(), + ..Default::default() + }) } else { None }; let z_only = if has_z { - let mut bm = Bm::default(); - bm.z_bits = label.z_bits.clone(); - Some(bm) + Some(Bm { + z_bits: label.z_bits.clone(), + ..Default::default() + }) } else { None }; @@ -264,6 +280,7 @@ fn classify_xz( /// and the exact formula for S. This gives correct results for stochastic /// noise and a Pauli-twirled approximation for coherent noise. The full /// coherent formula (with off-diagonal beta terms) is future work. +#[must_use] pub fn build_dem( generators: &[PropagatedEeg], detectors: &[Detector], @@ -273,16 +290,25 @@ pub fn build_dem( } /// Build DEM with stabilizer group for coherent interference. +#[must_use] pub fn build_dem_with_stabilizers( generators: &[PropagatedEeg], detectors: &[Detector], observables: &[Observable], stabilizer_group: Option<&StabilizerGroup>, ) -> Vec { - build_dem_inner(generators, detectors, observables, stabilizer_group, HFormula::Taylor, BchOrder::First) + build_dem_inner( + generators, + detectors, + observables, + stabilizer_group, + HFormula::Taylor, + BchOrder::First, + ) } /// Build DEM with all options via config struct. +#[must_use] pub fn build_dem_configured( generators: &[PropagatedEeg], detectors: &[Detector], @@ -290,10 +316,18 @@ pub fn build_dem_configured( stabilizer_group: Option<&StabilizerGroup>, config: &EegConfig, ) -> Vec { - build_dem_inner(generators, detectors, observables, stabilizer_group, config.h_formula, config.bch_order) + build_dem_inner( + generators, + detectors, + observables, + stabilizer_group, + config.h_formula, + config.bch_order, + ) } /// Build DEM with individual options (convenience). +#[must_use] pub fn build_dem_with_options( generators: &[PropagatedEeg], detectors: &[Detector], @@ -302,10 +336,16 @@ pub fn build_dem_with_options( h_formula: HFormula, bch_order: BchOrder, ) -> Vec { - build_dem_inner(generators, detectors, observables, stabilizer_group, h_formula, bch_order) + build_dem_inner( + generators, + detectors, + observables, + stabilizer_group, + h_formula, + bch_order, + ) } - fn build_dem_inner( generators: &[PropagatedEeg], detectors: &[Detector], @@ -353,8 +393,7 @@ fn build_dem_inner( let mut h_imag_by_label: BTreeMap = BTreeMap::new(); if bch_order == BchOrder::Second { - let h_entries: Vec<(Bm, f64)> = h_by_label.iter() - .map(|(l, &c)| (l.clone(), c)).collect(); + let h_entries: Vec<(Bm, f64)> = h_by_label.iter().map(|(l, &c)| (l.clone(), c)).collect(); for i in 0..h_entries.len() { for j in (i + 1)..h_entries.len() { @@ -370,10 +409,10 @@ fn build_dem_inner( let mag = h_i * h_j; let phase = (phase_k + 3) % 4; // -i^{k+1} = i^{k+3} let (re_coeff, im_coeff) = match phase { - 0 => (mag, 0.0), // 1 - 1 => (0.0, mag), // i - 2 => (-mag, 0.0), // -1 - 3 => (0.0, -mag), // -i + 0 => (mag, 0.0), // 1 + 1 => (0.0, mag), // i + 2 => (-mag, 0.0), // -1 + 3 => (0.0, -mag), // -i _ => unreachable!(), }; @@ -396,10 +435,8 @@ fn build_dem_inner( // detection: Re(i·h·s · β) = 0 for real β. The paper's O(ε^{3/2}) // error bound accounts for this. if bch_order == BchOrder::Second { - let h_entries: Vec<(Bm, f64)> = h_by_label.iter() - .map(|(l, &c)| (l.clone(), c)).collect(); - let s_entries: Vec<(Bm, f64)> = s_by_label.iter() - .map(|(l, &c)| (l.clone(), c)).collect(); + let h_entries: Vec<(Bm, f64)> = h_by_label.iter().map(|(l, &c)| (l.clone(), c)).collect(); + let s_entries: Vec<(Bm, f64)> = s_by_label.iter().map(|(l, &c)| (l.clone(), c)).collect(); for (p, _h_coeff) in &h_entries { for (q, _s_coeff) in &s_entries { @@ -425,7 +462,8 @@ fn build_dem_inner( *h_by_label.entry(label.clone()).or_insert(0.0) += re; } - let all_h_labels: std::collections::BTreeSet = h_by_label.keys() + let all_h_labels: std::collections::BTreeSet = h_by_label + .keys() .chain(h_imag_by_label.keys()) .cloned() .collect(); @@ -447,7 +485,10 @@ fn build_dem_inner( continue; } h_events.entry(event.clone()).or_default().push((re, im)); - event_pauli_labels.entry(event).or_default().push(label.clone()); + event_pauli_labels + .entry(event) + .or_default() + .push(label.clone()); } for (label, &coeff) in &s_by_label { @@ -468,7 +509,10 @@ fn build_dem_inner( let sum_rate: f64 = rates.iter().sum(); let prob = (1.0 - (2.0 * sum_rate).exp()) / 2.0; if prob.abs() > 1e-15 { - entries.push(DemEntry { event: event.clone(), probability: prob.abs() }); + entries.push(DemEntry { + event: event.clone(), + probability: prob.abs(), + }); } } @@ -476,7 +520,7 @@ fn build_dem_inner( // β(ψ, C_{Q1,Q2}, P) = ±4 if [Q1,Q2]=0, [Q1,P]≠0, [Q2,P]≠0, Q1Q2|ψ⟩=∓|ψ⟩ // β(ψ, A_{Q1,Q2}, P) = ±4 if [Q1,Q2]≠0, [Q1,P]≠0, [Q2,P]≠0, iQ1Q2|ψ⟩=±|ψ⟩ // These contribute at first order (same as S). - if let Some(ref stab_group) = stabilizer_group { + if let Some(stab_group) = stabilizer_group { for &(ref q1, ref q2, coeff) in c_generators.iter().chain(a_generators.iter()) { // Classify: both Q1 and Q2 must anticommute with the same detectors let event1 = classify(q1, detectors, observables); @@ -491,8 +535,12 @@ fn build_dem_inner( let is_c_type = c_generators.iter().any(|(a, b, _)| a == q1 && b == q2); // C requires [Q1,Q2]=0, A requires [Q1,Q2]≠0 - if is_c_type && !q1_q2_commute { continue; } - if !is_c_type && q1_q2_commute { continue; } + if is_c_type && !q1_q2_commute { + continue; + } + if !is_c_type && q1_q2_commute { + continue; + } // Check product stabilizer status let product = q1.multiply(q2); @@ -515,15 +563,21 @@ fn build_dem_inner( // A-type only contributes when iQ1Q2 has eigenvalue ±1, // which means Q1Q2 has eigenvalue ∓i. Skip for now since // stabilizer eigenvalues are always ±1. - if !is_c_type { continue; } + if !is_c_type { + continue; + } let prob_contribution = -coeff * beta_val / 2.0; if prob_contribution.abs() > 1e-15 { if let Some(existing) = entries.iter_mut().find(|e| e.event == event) { let p_s = existing.probability; - existing.probability = p_s + prob_contribution.abs() - 2.0 * p_s * prob_contribution.abs(); + existing.probability = + p_s + prob_contribution.abs() - 2.0 * p_s * prob_contribution.abs(); } else { - entries.push(DemEntry { event: event.clone(), probability: prob_contribution.abs() }); + entries.push(DemEntry { + event: event.clone(), + probability: prob_contribution.abs(), + }); } } } @@ -545,23 +599,29 @@ fn build_dem_inner( // If stabilizer_group is None, fall back to diagonal approximation. for (event, coeffs) in &h_events { // Collect the detector stabilizers for this event (for ExactCommuting) - let event_det_stab = if h_formula == HFormula::ExactCommuting || h_formula == HFormula::ExactSubset { - // XOR of all detector stabilizers in this event - let mut stab = Bm::default(); - for &d_id in &event.detectors { - if let Some(det) = detectors.iter().find(|d| d.id == d_id) { - stab = stab.multiply(&det.stabilizer); + let event_det_stab = + if h_formula == HFormula::ExactCommuting || h_formula == HFormula::ExactSubset { + // XOR of all detector stabilizers in this event + let mut stab = Bm::default(); + for &d_id in &event.detectors { + if let Some(det) = detectors.iter().find(|d| d.id == d_id) { + stab = stab.multiply(&det.stabilizer); + } } - } - Some(stab) - } else { - None - }; + Some(stab) + } else { + None + }; - let prob = if let Some(ref stab_group) = stabilizer_group { + let prob = if let Some(stab_group) = stabilizer_group { compute_h_probability_full( - coeffs, generators, &event_pauli_labels, event, - stab_group, h_formula, event_det_stab.as_ref(), + coeffs, + generators, + &event_pauli_labels, + event, + stab_group, + h_formula, + event_det_stab.as_ref(), ) } else { coeffs.iter().map(|&(re, im)| re * re + im * im).sum() @@ -571,7 +631,10 @@ fn build_dem_inner( let p_s = existing.probability; existing.probability = p_s + prob - 2.0 * p_s * prob; } else { - entries.push(DemEntry { event: event.clone(), probability: prob }); + entries.push(DemEntry { + event: event.clone(), + probability: prob, + }); } } } @@ -597,25 +660,24 @@ fn compute_h_probability_full( h_formula: HFormula, det_stabilizer: Option<&Bm>, ) -> f64 { - let labels = match event_labels.get(event) { - Some(l) => l, - None => return 0.0, + let Some(labels) = event_labels.get(event) else { + return 0.0; }; let n = coeffs.len(); // --- ExactCommuting: product formula for commuting generators --- - if h_formula == HFormula::ExactCommuting { - if let Some(det_stab) = det_stabilizer { - return compute_exact_commuting(coeffs, labels, stab_group, det_stab); - } + if h_formula == HFormula::ExactCommuting + && let Some(det_stab) = det_stabilizer + { + return compute_exact_commuting(coeffs, labels, stab_group, det_stab); } // --- ExactSubset: enumerate all even-size subsets --- - if h_formula == HFormula::ExactSubset { - if let Some(det_stab) = det_stabilizer { - return compute_exact_subset(coeffs, labels, stab_group, det_stab); - } + if h_formula == HFormula::ExactSubset + && let Some(det_stab) = det_stabilizer + { + return compute_exact_subset(coeffs, labels, stab_group, det_stab); } // --- Taylor or SinSquared: quadratic form with beta --- @@ -645,8 +707,12 @@ fn compute_h_probability_full( } match stab_group.is_stabilizer(&product) { - Some(true) => { total += re_product; } - Some(false) => { total -= re_product; } + Some(true) => { + total += re_product; + } + Some(false) => { + total -= re_product; + } None => {} } } @@ -656,12 +722,11 @@ fn compute_h_probability_full( let total = total.max(0.0); match h_formula { - HFormula::Taylor => total, HFormula::SinSquared => { let h_eff = total.sqrt(); h_eff.sin().powi(2) } - HFormula::ExactCommuting | HFormula::ExactSubset => total, // fallback if no detector + HFormula::Taylor | HFormula::ExactCommuting | HFormula::ExactSubset => total, } } @@ -688,7 +753,9 @@ fn compute_exact_commuting( let (h_re, h_im) = coeffs[j]; // For simplicity, use magnitude of complex coefficient let h = (h_re * h_re + h_im * h_im).sqrt(); - if h < 1e-20 { continue; } + if h < 1e-20 { + continue; + } let label = &labels[j]; @@ -760,8 +827,7 @@ fn compute_exact_subset( // Precompute sin(2h_j) and cos(2h_j) for each generator let mut sin2h = Vec::with_capacity(n); let mut cos2h = Vec::with_capacity(n); - for j in 0..n { - let (h_re, h_im) = coeffs[j]; + for &(h_re, h_im) in coeffs.iter().take(n) { let h = (h_re * h_re + h_im * h_im).sqrt(); sin2h.push((2.0 * h).sin()); cos2h.push((2.0 * h).cos()); @@ -778,15 +844,15 @@ fn compute_exact_subset( let total_subsets = 1u64 << n; for mask in 1..total_subsets { let size = mask.count_ones() as usize; - if size % 2 != 0 { + if !size.is_multiple_of(2) { continue; // odd-size subsets have Im(i^|S|) only → Re = 0 } // Compute product of labels in S, multiplied by det_stab (D) let mut product = det_stab.clone(); - for j in 0..n { + for (j, label) in labels.iter().enumerate().take(n) { if mask & (1u64 << j) != 0 { - product = product.multiply(&labels[j]); + product = product.multiply(label); } } @@ -804,14 +870,18 @@ fn compute_exact_subset( }; // Coefficient: (-1)^{|S|/2} · Π_{j∈S} sin(2h_j) · Π_{j∉S} cos(2h_j) - let sign = if (size / 2) % 2 == 0 { 1.0 } else { -1.0 }; + let sign = if (size / 2).is_multiple_of(2) { + 1.0 + } else { + -1.0 + }; let mut coeff = sign; - for j in 0..n { + for (j, (&sin, &cos)) in sin2h.iter().zip(&cos2h).enumerate().take(n) { if mask & (1u64 << j) != 0 { - coeff *= sin2h[j]; + coeff *= sin; } else { - coeff *= cos2h[j]; + coeff *= cos; } } @@ -838,14 +908,22 @@ pub fn sensitivity_matrix( detectors: &[Detector], observables: &[Observable], stabilizer_group: Option<&StabilizerGroup>, -) -> BTreeMap> { +) -> BTreeMap< + DemEvent, + Vec<( + crate::circuit::NoiseSource, + crate::circuit::NoiseSource, + f64, + )>, +> { use crate::circuit::NoiseSource; use crate::eeg::EegType; let mut result = BTreeMap::new(); // Collect H generators with their sources - let h_gens: Vec<_> = generators.iter() + let h_gens: Vec<_> = generators + .iter() .filter(|g| g.eeg_type == EegType::H && g.source.is_some()) .collect(); @@ -875,23 +953,21 @@ pub fn sensitivity_matrix( // Beta coefficient for pair (i,j) let beta_val: f64 = if i == j { 1.0 // diagonal: beta = -4, but -(1/4)*(-4) = 1 - } else { - if !label_i.commutes_with(label_j) { - 0.0 - } else { - let product = label_i.multiply(label_j); - if product.is_identity() { - 1.0 - } else if let Some(stab) = stabilizer_group { - match stab.is_stabilizer(&product) { - Some(true) => 1.0, - Some(false) => -1.0, - None => 0.0, - } - } else { - 0.0 + } else if label_i.commutes_with(label_j) { + let product = label_i.multiply(label_j); + if product.is_identity() { + 1.0 + } else if let Some(stab) = stabilizer_group { + match stab.is_stabilizer(&product) { + Some(true) => 1.0, + Some(false) => -1.0, + None => 0.0, } + } else { + 0.0 } + } else { + 0.0 }; if beta_val.abs() > 1e-15_f64 { @@ -912,6 +988,7 @@ pub fn sensitivity_matrix( /// /// Same as `build_dem_configured` but includes X/Z component decomposition /// for each mechanism, enabling proper graphlike decomposition for MWPM decoders. +#[must_use] pub fn build_dem_decomposable( generators: &[PropagatedEeg], detectors: &[Detector], @@ -920,18 +997,14 @@ pub fn build_dem_decomposable( config: &EegConfig, ) -> Vec { // First, build the standard DEM entries with the requested config - let standard_entries = build_dem_configured( - generators, detectors, observables, stabilizer_group, config, - ); + let standard_entries = + build_dem_configured(generators, detectors, observables, stabilizer_group, config); // Build a map from combined event → (x_component, z_component) // by classifying each unique label's X/Z components. // Multiple generators may contribute to the same event, but their // X/Z classification should be consistent (same combined effect = same decomposition). - let mut event_xz: BTreeMap< - (SmallVec<[usize; 4]>, SmallVec<[usize; 2]>), - (Option, Option), - > = BTreeMap::new(); + let mut event_xz: BTreeMap = BTreeMap::new(); for g in generators { let (combined, x_ev, z_ev) = classify_xz(&g.label, detectors, observables); @@ -941,19 +1014,22 @@ pub fn build_dem_decomposable( } // Convert standard entries to decomposable entries - standard_entries.into_iter().map(|entry| { - let key = (entry.event.detectors.clone(), entry.event.observables.clone()); - let (x_comp, z_comp) = event_xz - .get(&key) - .cloned() - .unwrap_or((None, None)); - DecomposableDemEntry { - event: entry.event, - probability: entry.probability, - x_component: x_comp, - z_component: z_comp, - } - }).collect() + standard_entries + .into_iter() + .map(|entry| { + let key = ( + entry.event.detectors.clone(), + entry.event.observables.clone(), + ); + let (x_comp, z_comp) = event_xz.get(&key).cloned().unwrap_or((None, None)); + DecomposableDemEntry { + event: entry.event, + probability: entry.probability, + x_component: x_comp, + z_component: z_comp, + } + }) + .collect() } /// Format DEM entries as a Stim-compatible string. @@ -969,7 +1045,11 @@ pub fn format_dem(entries: &[DemEntry]) -> String { parts.push(format!("L{o}")); } if !parts.is_empty() { - lines.push(format!("error({:.6e}) {}", entry.probability, parts.join(" "))); + lines.push(format!( + "error({:.6e}) {}", + entry.probability, + parts.join(" ") + )); } } lines.join("\n") @@ -982,6 +1062,7 @@ pub fn format_dem(entries: &[DemEntry]) -> String { /// Single-component hyperedges (3+ detectors) are decomposed via a graphlike /// index: expressed as XOR of existing graphlike mechanisms. If no decomposition /// exists, the mechanism is dropped (cannot be used by MWPM decoders). +#[must_use] pub fn format_dem_decomposed(entries: &[DecomposableDemEntry]) -> String { use std::collections::{BTreeMap, BTreeSet}; @@ -1000,46 +1081,13 @@ pub fn format_dem_decomposed(entries: &[DecomposableDemEntry]) -> String { ev.detectors.len() <= 2 } - // Step 1: Collect all graphlike mechanisms (building blocks for decomposition) - let mut graphlike_set: BTreeSet> = BTreeSet::new(); - for entry in entries { - if entry.probability <= 0.0 { continue; } - // Collect graphlike from X/Z components - if let Some(ref x) = entry.x_component { - if is_graphlike(x) && !x.detectors.is_empty() { - graphlike_set.insert(x.detectors.clone()); - } - } - if let Some(ref z) = entry.z_component { - if is_graphlike(z) && !z.detectors.is_empty() { - graphlike_set.insert(z.detectors.clone()); - } - } - // Also from combined event - if is_graphlike(&entry.event) && !entry.event.detectors.is_empty() { - graphlike_set.insert(entry.event.detectors.clone()); - } - } - - // Step 2: Build index for graphlike decomposition search - let max_det = graphlike_set.iter() - .flat_map(|d| d.iter().copied()) - .max() - .unwrap_or(0); - let mut by_det: Vec>> = vec![Vec::new(); max_det + 1]; - for g in &graphlike_set { - for &d in g.iter() { - by_det[d].push(g.clone()); - } - } - // Search for decomposition of a hyperedge into XOR of graphlike pieces fn search_decomp( - remaining: &SmallVec<[usize; 4]>, - by_det: &[Vec>], - graphlike_set: &BTreeSet>, - memo: &mut BTreeMap, Option>>>, - ) -> Option>> { + remaining: &DetectorSet, + by_det: &[Vec], + graphlike_set: &BTreeSet, + memo: &mut DecompMemo, + ) -> Option { if let Some(cached) = memo.get(remaining) { return cached.clone(); } @@ -1072,14 +1120,33 @@ pub fn format_dem_decomposed(entries: &[DecomposableDemEntry]) -> String { let r = remaining; let c = candidate; while i < r.len() && j < c.len() { - if r[i] < c[j] { next.push(r[i]); i += 1; } - else if r[i] > c[j] { next.push(c[j]); j += 1; } - else { i += 1; j += 1; } // shared → cancel + match r[i].cmp(&c[j]) { + std::cmp::Ordering::Less => { + next.push(r[i]); + i += 1; + } + std::cmp::Ordering::Greater => { + next.push(c[j]); + j += 1; + } + std::cmp::Ordering::Equal => { + i += 1; + j += 1; + } + } + } + while i < r.len() { + next.push(r[i]); + i += 1; + } + while j < c.len() { + next.push(c[j]); + j += 1; } - while i < r.len() { next.push(r[i]); i += 1; } - while j < c.len() { next.push(c[j]); j += 1; } - if next.len() >= remaining.len() { continue; } // must make progress + if next.len() >= remaining.len() { + continue; + } // must make progress if let Some(suffix) = search_decomp(&next, by_det, graphlike_set, memo) { let mut result = vec![candidate.clone()]; @@ -1095,9 +1162,47 @@ pub fn format_dem_decomposed(entries: &[DecomposableDemEntry]) -> String { None } + // Step 1: Collect all graphlike mechanisms (building blocks for decomposition) + let mut graphlike_set: BTreeSet> = BTreeSet::new(); + for entry in entries { + if entry.probability <= 0.0 { + continue; + } + // Collect graphlike from X/Z components + if let Some(ref x) = entry.x_component + && is_graphlike(x) + && !x.detectors.is_empty() + { + graphlike_set.insert(x.detectors.clone()); + } + if let Some(ref z) = entry.z_component + && is_graphlike(z) + && !z.detectors.is_empty() + { + graphlike_set.insert(z.detectors.clone()); + } + // Also from combined event + if is_graphlike(&entry.event) && !entry.event.detectors.is_empty() { + graphlike_set.insert(entry.event.detectors.clone()); + } + } + + // Step 2: Build index for graphlike decomposition search + let max_det = graphlike_set + .iter() + .flat_map(|d| d.iter().copied()) + .max() + .unwrap_or(0); + let mut by_det: Vec>> = vec![Vec::new(); max_det + 1]; + for g in &graphlike_set { + for &d in g { + by_det[d].push(g.clone()); + } + } + // Step 3: Format entries let mut by_targets: BTreeMap = BTreeMap::new(); - let mut memo: BTreeMap, Option>>> = BTreeMap::new(); + let mut memo: DecompMemo = BTreeMap::new(); for entry in entries { if entry.probability <= 0.0 { @@ -1122,13 +1227,19 @@ pub fn format_dem_decomposed(entries: &[DecomposableDemEntry]) -> String { // Hyperedge X-only: try graphlike decomposition match search_decomp(&x.detectors, &by_det, &graphlike_set, &mut memo) { Some(pieces) => { - let mut parts: Vec = pieces.iter().map(|p| { - p.iter().map(|d| format!("D{d}")).collect::>().join(" ") - }).collect(); + let mut parts: Vec = pieces + .iter() + .map(|p| { + p.iter() + .map(|d| format!("D{d}")) + .collect::>() + .join(" ") + }) + .collect(); // Attach observables to first piece if !x.observables.is_empty() && !parts.is_empty() { for &o in &x.observables { - parts[0].push_str(&format!(" L{o}")); + let _ = write!(&mut parts[0], " L{o}"); } } parts.join(" ^ ") @@ -1144,12 +1255,18 @@ pub fn format_dem_decomposed(entries: &[DecomposableDemEntry]) -> String { // Hyperedge Z-only: try graphlike decomposition match search_decomp(&z.detectors, &by_det, &graphlike_set, &mut memo) { Some(pieces) => { - let mut parts: Vec = pieces.iter().map(|p| { - p.iter().map(|d| format!("D{d}")).collect::>().join(" ") - }).collect(); + let mut parts: Vec = pieces + .iter() + .map(|p| { + p.iter() + .map(|d| format!("D{d}")) + .collect::>() + .join(" ") + }) + .collect(); if !z.observables.is_empty() && !parts.is_empty() { for &o in &z.observables { - parts[0].push_str(&format!(" L{o}")); + let _ = write!(&mut parts[0], " L{o}"); } } parts.join(" ^ ") @@ -1163,14 +1280,21 @@ pub fn format_dem_decomposed(entries: &[DecomposableDemEntry]) -> String { format_event(&entry.event) } else { // Combined hyperedge without components: try graphlike decomposition - match search_decomp(&entry.event.detectors, &by_det, &graphlike_set, &mut memo) { + match search_decomp(&entry.event.detectors, &by_det, &graphlike_set, &mut memo) + { Some(pieces) => { - let mut parts: Vec = pieces.iter().map(|p| { - p.iter().map(|d| format!("D{d}")).collect::>().join(" ") - }).collect(); + let mut parts: Vec = pieces + .iter() + .map(|p| { + p.iter() + .map(|d| format!("D{d}")) + .collect::>() + .join(" ") + }) + .collect(); if !entry.event.observables.is_empty() && !parts.is_empty() { for &o in &entry.event.observables { - parts[0].push_str(&format!(" L{o}")); + let _ = write!(&mut parts[0], " L{o}"); } } parts.join(" ^ ") @@ -1222,7 +1346,8 @@ mod tests { label: Bm::x(0), label2: None, coeff: -0.01, - source: None, }]; + source: None, + }]; let dets = vec![z_det(0, &[0])]; // Z0 anticommutes with X0 let entries = build_dem(&gens, &dets, &[]); @@ -1239,7 +1364,8 @@ mod tests { label: Bm::x(0), label2: None, coeff: 0.1, - source: None, }]; + source: None, + }]; let dets = vec![z_det(0, &[0])]; let entries = build_dem(&gens, &dets, &[]); @@ -1252,8 +1378,20 @@ mod tests { // Two H generators in same event class: rates don't add (diagonal approx) // p = h1^2 + h2^2 (NOT (h1+h2)^2 — that would be coherent accumulation) let gens = vec![ - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.1 , source: None }, - PropagatedEeg { eeg_type: EegType::H, label: Bm::y(0), label2: None, coeff: 0.05 , source: None }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: 0.1, + source: None, + }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::y(0), + label2: None, + coeff: 0.05, + source: None, + }, ]; let dets = vec![z_det(0, &[0])]; // Both X0 and Y0 anticommute with Z0 let entries = build_dem(&gens, &dets, &[]); @@ -1271,7 +1409,8 @@ mod tests { label: Bm::z(0), label2: None, coeff: 0.1, - source: None, }]; + source: None, + }]; let dets = vec![z_det(0, &[0])]; let entries = build_dem(&gens, &dets, &[]); @@ -1283,16 +1422,31 @@ mod tests { // Two H generators with SAME Pauli label: BCH sums coefficients. // Two H_X(0) with rates 0.1 and 0.05 → combined rate 0.15 → p = 0.15^2 let gens = vec![ - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.1 , source: None }, - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.05 , source: None }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: 0.1, + source: None, + }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: 0.05, + source: None, + }, ]; let dets = vec![z_det(0, &[0])]; let entries = build_dem(&gens, &dets, &[]); // BCH combines: single generator with rate 0.15, p = 0.15^2 = 0.0225 assert_eq!(entries.len(), 1); - assert!((entries[0].probability - 0.0225).abs() < 1e-10, - "BCH should sum same-label rates: got {}", entries[0].probability); + assert!( + (entries[0].probability - 0.0225).abs() < 1e-10, + "BCH should sum same-label rates: got {}", + entries[0].probability + ); } #[test] @@ -1308,29 +1462,47 @@ mod tests { Gate { gate_type: gt, qubits: GateQubits::from_iter(qs.iter().map(|&q| QubitId(q))), - angles: GateAngles::new(), params: GateParams::new(), - meas_ids: pecos_core::GateMeasIds::new(), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), } } let gens = vec![ - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.1 , source: None }, - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(1), label2: None, coeff: 0.05 , source: None }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: 0.1, + source: None, + }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(1), + label2: None, + coeff: 0.05, + source: None, + }, ]; // Z0Z1 detector: X0 and X1 both anticommute with it - let dets = vec![Detector { id: 0, stabilizer: Bm::z(0).multiply(&Bm::z(1)) }]; + let dets = vec![Detector { + id: 0, + stabilizer: Bm::z(0).multiply(&Bm::z(1)), + }]; // |Phi+> = H CX |00> → stabilizers +X0X1, +Z0Z1 - let stab_group = StabilizerGroup::from_circuit( - &[g(GateType::H, &[0]), g(GateType::CX, &[0, 1])], 2, - ); + let stab_group = + StabilizerGroup::from_circuit(&[g(GateType::H, &[0]), g(GateType::CX, &[0, 1])], 2); let entries = build_dem_with_stabilizers(&gens, &dets, &[], Some(&stab_group)); assert_eq!(entries.len(), 1); // X0*X1 is +1 stabilizer → constructive: (0.1+0.05)^2 = 0.0225 - assert!((entries[0].probability - 0.0225).abs() < 1e-10, - "Constructive beta: got {}, expected 0.0225", entries[0].probability); + assert!( + (entries[0].probability - 0.0225).abs() < 1e-10, + "Constructive beta: got {}, expected 0.0225", + entries[0].probability + ); } #[test] @@ -1345,28 +1517,52 @@ mod tests { Gate { gate_type: gt, qubits: GateQubits::from_iter(qs.iter().map(|&q| QubitId(q))), - angles: GateAngles::new(), params: GateParams::new(), - meas_ids: pecos_core::GateMeasIds::new(), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), } } let gens = vec![ - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.1 , source: None }, - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(1), label2: None, coeff: 0.05 , source: None }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: 0.1, + source: None, + }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(1), + label2: None, + coeff: 0.05, + source: None, + }, ]; - let dets = vec![Detector { id: 0, stabilizer: Bm::z(0).multiply(&Bm::z(1)) }]; + let dets = vec![Detector { + id: 0, + stabilizer: Bm::z(0).multiply(&Bm::z(1)), + }]; // |Phi-> = CX H X |00> → stabilizers -X0X1, +Z0Z1 let stab_group = StabilizerGroup::from_circuit( - &[g(GateType::X, &[0]), g(GateType::H, &[0]), g(GateType::CX, &[0, 1])], 2, + &[ + g(GateType::X, &[0]), + g(GateType::H, &[0]), + g(GateType::CX, &[0, 1]), + ], + 2, ); let entries = build_dem_with_stabilizers(&gens, &dets, &[], Some(&stab_group)); assert_eq!(entries.len(), 1); // X0*X1 is -1 stabilizer → destructive: (0.1-0.05)^2 = 0.0025 - assert!((entries[0].probability - 0.0025).abs() < 1e-10, - "Destructive beta: got {}, expected 0.0025", entries[0].probability); + assert!( + (entries[0].probability - 0.0025).abs() < 1e-10, + "Destructive beta: got {}, expected 0.0025", + entries[0].probability + ); } #[test] @@ -1380,26 +1576,49 @@ mod tests { Gate { gate_type: gt, qubits: GateQubits::from_iter(qs.iter().map(|&q| QubitId(q))), - angles: GateAngles::new(), params: GateParams::new(), - meas_ids: pecos_core::GateMeasIds::new(), + angles: GateAngles::new(), + params: GateParams::new(), + meas_ids: pecos_core::GateMeasIds::new(), } } let gens = vec![ - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.1 , source: None }, - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(1), label2: None, coeff: 0.1 , source: None }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: 0.1, + source: None, + }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(1), + label2: None, + coeff: 0.1, + source: None, + }, ]; - let dets = vec![Detector { id: 0, stabilizer: Bm::z(0).multiply(&Bm::z(1)) }]; + let dets = vec![Detector { + id: 0, + stabilizer: Bm::z(0).multiply(&Bm::z(1)), + }]; let stab_group = StabilizerGroup::from_circuit( - &[g(GateType::X, &[0]), g(GateType::H, &[0]), g(GateType::CX, &[0, 1])], 2, + &[ + g(GateType::X, &[0]), + g(GateType::H, &[0]), + g(GateType::CX, &[0, 1]), + ], + 2, ); let entries = build_dem_with_stabilizers(&gens, &dets, &[], Some(&stab_group)); // Complete cancellation: p = 0 - assert!(entries.is_empty(), - "Equal-rate destructive interference should cancel completely"); + assert!( + entries.is_empty(), + "Equal-rate destructive interference should cancel completely" + ); } #[test] @@ -1410,10 +1629,25 @@ mod tests { use crate::stabilizer::StabilizerGroup; let gens = vec![ - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: 0.1 , source: None }, - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(1), label2: None, coeff: 0.05 , source: None }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: 0.1, + source: None, + }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(1), + label2: None, + coeff: 0.05, + source: None, + }, ]; - let dets = vec![Detector { id: 0, stabilizer: Bm::z(0).multiply(&Bm::z(1)) }]; + let dets = vec![Detector { + id: 0, + stabilizer: Bm::z(0).multiply(&Bm::z(1)), + }]; let stab_group = StabilizerGroup::from_circuit(&[], 2); @@ -1421,8 +1655,11 @@ mod tests { assert_eq!(entries.len(), 1); // p = h1^2 + h2^2 = 0.0125 (diagonal only) - assert!((entries[0].probability - 0.0125).abs() < 1e-10, - "Non-stabilizer product → diagonal: got {}", entries[0].probability); + assert!( + (entries[0].probability - 0.0125).abs() < 1e-10, + "Non-stabilizer product → diagonal: got {}", + entries[0].probability + ); } #[test] @@ -1430,8 +1667,20 @@ mod tests { // Multiple S generators in same event class: exact formula // p = (1/2)(1 - exp(2 * sum_rates)) let gens = vec![ - PropagatedEeg { eeg_type: EegType::S, label: Bm::x(0), label2: None, coeff: -0.01 , source: None }, - PropagatedEeg { eeg_type: EegType::S, label: Bm::y(0), label2: None, coeff: -0.005 , source: None }, + PropagatedEeg { + eeg_type: EegType::S, + label: Bm::x(0), + label2: None, + coeff: -0.01, + source: None, + }, + PropagatedEeg { + eeg_type: EegType::S, + label: Bm::y(0), + label2: None, + coeff: -0.005, + source: None, + }, ]; let dets = vec![z_det(0, &[0])]; let entries = build_dem(&gens, &dets, &[]); @@ -1450,9 +1699,13 @@ mod tests { label: Bm::x(0), label2: None, coeff: 0.1, - source: None, }]; + source: None, + }]; let dets = vec![z_det(0, &[1])]; // Detector on qubit 1 - let obs = vec![Observable { id: 0, pauli: Bm::z(0) }]; // Observable Z0 + let obs = vec![Observable { + id: 0, + pauli: Bm::z(0), + }]; // Observable Z0 let entries = build_dem(&gens, &dets, &obs); @@ -1478,18 +1731,32 @@ mod tests { let h_z = 0.05; let gens = vec![ - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: h_x, source: None }, - PropagatedEeg { eeg_type: EegType::H, label: Bm::z(0), label2: None, coeff: h_z, source: None }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: h_x, + source: None, + }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::z(0), + label2: None, + coeff: h_z, + source: None, + }, ]; let dets = vec![z_det(0, &[0])]; // Z detector: X and Y anticommute, Z commutes // Without BCH2: only X flips detector. p = h_x² = 0.01 - let entries_k1 = build_dem_with_options( - &gens, &dets, &[], None, HFormula::Taylor, BchOrder::First, - ); + let entries_k1 = + build_dem_with_options(&gens, &dets, &[], None, HFormula::Taylor, BchOrder::First); let p_k1: f64 = entries_k1.iter().map(|e| e.probability).sum(); - assert!((p_k1 - h_x * h_x).abs() < 1e-10, - "BCH1: p should be h_x² = {}, got {p_k1}", h_x * h_x); + assert!( + (p_k1 - h_x * h_x).abs() < 1e-10, + "BCH1: p should be h_x² = {}, got {p_k1}", + h_x * h_x + ); // With BCH2: adds H_Y with imaginary coeff -i * h_x * h_z. // Y anticommutes with Z detector → flips it. @@ -1499,13 +1766,14 @@ mod tests { // re_X = h_x, im_X = 0. re_Y = 0, im_Y = -h_x*h_z. // re_product = h_x * 0 - 0 * (-h_x*h_z) = 0. Cross-term is zero. // So BCH2 only adds the diagonal of the Y generator: |im_Y|² = (h_x * h_z)² = 0.000025. - let entries_k2 = build_dem_with_options( - &gens, &dets, &[], None, HFormula::Taylor, BchOrder::Second, - ); + let entries_k2 = + build_dem_with_options(&gens, &dets, &[], None, HFormula::Taylor, BchOrder::Second); let p_k2: f64 = entries_k2.iter().map(|e| e.probability).sum(); let expected_k2 = h_x * h_x + (h_x * h_z).powi(2); - assert!((p_k2 - expected_k2).abs() < 1e-10, - "BCH2: p should be h_x² + (h_x·h_z)² = {expected_k2}, got {p_k2}"); + assert!( + (p_k2 - expected_k2).abs() < 1e-10, + "BCH2: p should be h_x² + (h_x·h_z)² = {expected_k2}, got {p_k2}" + ); // BCH2 adds a small correction: 0.01 + 0.000025 = 0.010025 assert!(p_k2 > p_k1, "BCH2 should add to probability"); diff --git a/exp/pecos-eeg/src/dem_simulator.rs b/exp/pecos-eeg/src/dem_simulator.rs index 7d028b236..2493d2efe 100644 --- a/exp/pecos-eeg/src/dem_simulator.rs +++ b/exp/pecos-eeg/src/dem_simulator.rs @@ -27,10 +27,13 @@ use crate::dem_generator::{DemContext, DemGenerator}; use crate::expand::{ExpandedCircuit, GateIndex}; use crate::noise::UniformNoise; +use pecos_core::Gate; use pecos_core::gate_type::GateType; use pecos_core::pauli::pauli_bitmask::BitmaskStorage; -use pecos_core::Gate; use pecos_qec::fault_tolerance::dem_builder::ParsedDem; +use pecos_qec::fault_tolerance::fault_sampler::{ + RawMeasurementPlan, StochasticNoiseParams, symbolic_measurement_history, +}; use pecos_quantum::TickCircuit; use pecos_random::PecosRng; @@ -108,16 +111,11 @@ fn try_stochastic_path( } // Build TickCircuit using typed API (proper measurement record tracking) - let mut tc = build_tick_circuit(gates, meta)?; + let mut tc = build_tick_circuit(gates, meta); // Compact ticks to reduce DAG complexity (critical for performance) tc.compact_ticks(); - // Build raw measurement plan via shared symbolic sim + fault table - use pecos_qec::fault_tolerance::fault_sampler::{ - symbolic_measurement_history, RawMeasurementPlan, StochasticNoiseParams, - }; - let history = symbolic_measurement_history(&tc).ok()?; let noise_params = StochasticNoiseParams { @@ -152,7 +150,7 @@ fn try_stochastic_path( /// After building all gates, creates detector/observable annotations using /// the stored measurement references. This ensures the DagCircuit conversion /// and DagFaultAnalyzer see proper structured annotations. -fn build_tick_circuit(gates: &[Gate], meta: &CircuitMeasurementMeta) -> Option { +fn build_tick_circuit(gates: &[Gate], meta: &CircuitMeasurementMeta) -> TickCircuit { use pecos_quantum::{Attribute, TickMeasRef}; let mut tc = TickCircuit::default(); @@ -231,7 +229,7 @@ fn build_tick_circuit(gates: &[Gate], meta: &CircuitMeasurementMeta) -> Option ExpandedCircuit { let max_qubit = gates .iter() .flat_map(|g| g.qubits.iter()) - .map(|q| q.index()) + .map(pecos_core::QubitId::index) .max() .unwrap_or(0); let num_original = max_qubit + 1; @@ -156,6 +156,7 @@ impl ExpandedCircuit { /// /// Z on auxiliary qubits is dropped (doesn't correspond to original). /// Components on original qubits pass through unchanged. + #[must_use] pub fn map_to_original_frame(&self, p: &Bm) -> Bm { let mut result = Bm::default(); @@ -196,6 +197,7 @@ pub struct GateIndex { impl GateIndex { /// Build the index from a gate list (typically the expanded circuit). + #[must_use] pub fn build(gates: &[Gate], num_qubits: usize) -> Self { let mut qubit_gates = vec![Vec::new(); num_qubits]; @@ -227,25 +229,33 @@ impl GateIndex { } } - Self { qubit_gates, expansion_gates: expansion } + Self { + qubit_gates, + expansion_gates: expansion, + } } /// Gate indices touching qubit `q` in reverse order (for backward walk). pub fn gates_on_qubit_rev(&self, q: usize) -> impl Iterator + '_ { - self.qubit_gates.get(q).into_iter().flat_map(|v| v.iter().copied().rev()) + self.qubit_gates + .get(q) + .into_iter() + .flat_map(|v| v.iter().copied().rev()) } /// Is this gate an expansion gate (no physical noise)? #[inline] + #[must_use] pub fn is_expansion(&self, gate_idx: usize) -> bool { self.expansion_gates.get(gate_idx).copied().unwrap_or(false) } } +#[must_use] pub fn make_gate(gt: GateType, qubits: &[usize]) -> Gate { Gate { gate_type: gt, - qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + qubits: qubits.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), @@ -267,10 +277,10 @@ mod tests { let gates = vec![ gate(GateType::PZ, &[0]), gate(GateType::H, &[0]), - gate(GateType::MZ, &[0]), // → CX(0, aux0) - gate(GateType::PZ, &[0]), // reset + gate(GateType::MZ, &[0]), // → CX(0, aux0) + gate(GateType::PZ, &[0]), // reset gate(GateType::H, &[0]), - gate(GateType::MZ, &[0]), // → CX(0, aux1) + gate(GateType::MZ, &[0]), // → CX(0, aux1) ]; let expanded = expand_circuit(&gates); @@ -288,7 +298,9 @@ mod tests { assert_eq!(mid_mz, 0, "No mid-circuit MZ in expanded circuit"); // Two MZ at the end (one per auxiliary) - let end_mz = expanded.gates.iter() + let end_mz = expanded + .gates + .iter() .rev() .take_while(|g| g.gate_type == GateType::MZ) .count(); @@ -318,8 +330,8 @@ mod tests { gate(GateType::PZ, &[0, 1]), gate(GateType::H, &[0]), gate(GateType::CX, &[0, 1]), - gate(GateType::MZ, &[0]), // meas record 0 → aux 2 - gate(GateType::MZ, &[1]), // meas record 1 → aux 3 + gate(GateType::MZ, &[0]), // meas record 0 → aux 2 + gate(GateType::MZ, &[1]), // meas record 1 → aux 3 ]; let expanded = expand_circuit(&gates); @@ -333,7 +345,7 @@ mod tests { // X on auxiliary → X on original measured qubit let gates = vec![ gate(GateType::PZ, &[0]), - gate(GateType::MZ, &[0]), // meas 0 → aux 1 + gate(GateType::MZ, &[0]), // meas 0 → aux 1 ]; let expanded = expand_circuit(&gates); @@ -346,10 +358,7 @@ mod tests { #[test] fn test_map_to_original_frame_z_on_aux_dropped() { // Z on auxiliary is dropped (measurement projection absorbs it) - let gates = vec![ - gate(GateType::PZ, &[0]), - gate(GateType::MZ, &[0]), - ]; + let gates = vec![gate(GateType::PZ, &[0]), gate(GateType::MZ, &[0])]; let expanded = expand_circuit(&gates); let p = Bm::z(1); // Z on aux @@ -360,10 +369,7 @@ mod tests { #[test] fn test_map_to_original_frame_original_passthrough() { // Components on original qubits pass through unchanged - let gates = vec![ - gate(GateType::PZ, &[0, 1]), - gate(GateType::MZ, &[0]), - ]; + let gates = vec![gate(GateType::PZ, &[0, 1]), gate(GateType::MZ, &[0])]; let expanded = expand_circuit(&gates); let p = Bm::x(0).multiply(&Bm::z(1)); // X0 Z1 @@ -397,37 +403,51 @@ mod tests { gate(GateType::PZ, &[1]), gate(GateType::H, &[1]), gate(GateType::CX, &[1, 0]), - gate(GateType::MZ, &[1]), // round 1 syndrome - gate(GateType::PZ, &[1]), // reset + gate(GateType::MZ, &[1]), // round 1 syndrome + gate(GateType::PZ, &[1]), // reset gate(GateType::H, &[1]), gate(GateType::CX, &[1, 0]), - gate(GateType::MZ, &[1]), // round 2 syndrome (last round, no PZ after) - gate(GateType::MZ, &[0]), // data readout + gate(GateType::MZ, &[1]), // round 2 syndrome (last round, no PZ after) + gate(GateType::MZ, &[0]), // data readout ]; let expanded = expand_circuit(&gates); // Count PZ/QAlloc gates on qubit 1 in the expanded circuit - let resets_on_1: Vec<_> = expanded.gates.iter() - .filter(|g| (g.gate_type == GateType::PZ || g.gate_type == GateType::QAlloc) - && g.qubits.iter().any(|q| q.index() == 1)) + let resets_on_1: Vec<_> = expanded + .gates + .iter() + .filter(|g| { + (g.gate_type == GateType::PZ || g.gate_type == GateType::QAlloc) + && g.qubits.iter().any(|q| q.index() == 1) + }) .collect(); // Should have: original PZ(1) init + expansion PZ(1) round 1 + circuit PZ(1) reset // + expansion PZ(1) round 2 = 4 reset gates on qubit 1 eprintln!("Resets on qubit 1: {} gates", resets_on_1.len()); - assert!(resets_on_1.len() >= 4, + assert!( + resets_on_1.len() >= 4, "Should have expansion PZ for last-round MZ(1): got {} on q1", - resets_on_1.len()); + resets_on_1.len() + ); // Count resets on qubit 0 in expanded circuit - let resets_on_0: Vec<_> = expanded.gates.iter() - .filter(|g| (g.gate_type == GateType::PZ || g.gate_type == GateType::QAlloc) - && g.qubits.iter().any(|q| q.index() == 0)) + let resets_on_0: Vec<_> = expanded + .gates + .iter() + .filter(|g| { + (g.gate_type == GateType::PZ || g.gate_type == GateType::QAlloc) + && g.qubits.iter().any(|q| q.index() == 0) + }) .collect(); // Should have only: original PZ(0) init = 1 eprintln!("Resets on qubit 0: {} gates", resets_on_0.len()); - assert_eq!(resets_on_0.len(), 1, "Data qubit should NOT get expansion PZ"); + assert_eq!( + resets_on_0.len(), + 1, + "Data qubit should NOT get expansion PZ" + ); } #[test] diff --git a/exp/pecos-eeg/src/heisenberg.rs b/exp/pecos-eeg/src/heisenberg.rs index 2bed94bf7..671897ad2 100644 --- a/exp/pecos-eeg/src/heisenberg.rs +++ b/exp/pecos-eeg/src/heisenberg.rs @@ -27,10 +27,42 @@ use crate::Bm; use crate::noise::NoiseSpec; use crate::stabilizer::StabilizerGroup; -use pecos_core::gate_type::GateType; -use pecos_core::pauli::pauli_bitmask::*; use pecos_core::Gate; +use pecos_core::gate_type::GateType; +use pecos_core::pauli::pauli_bitmask::BitmaskStorage; use smallvec::SmallVec; +use std::collections::BinaryHeap; + +const CX_PHASE: [[u8; 4]; 4] = [[0, 0, 0, 0], [0, 0, 3, 1], [0, 1, 0, 3], [0, 3, 1, 0]]; + +fn sign_parity(signs: [bool; N]) -> bool { + signs.into_iter().fold(false, |parity, sign| parity ^ sign) +} + +fn activate_qubit( + q: u16, + before_gate: u32, + active: &mut [bool], + visited: &mut [bool], + heap: &mut BinaryHeap, + gate_index: &crate::expand::GateIndex, +) { + let qu = q as usize; + if qu >= active.len() { + return; + } + active[qu] = true; + for gi in gate_index.gates_on_qubit_rev(qu) { + if gi >= before_gate { + continue; + } // already passed + let gi_usize = gi as usize; + if !visited[gi_usize] { + visited[gi_usize] = true; + heap.push(gi); + } + } +} /// Precomputed noise for a single gate: H-type injections + batched S-type scale. /// @@ -79,8 +111,8 @@ pub fn build_noise_map( continue; } - let qubits: SmallVec<[usize; 4]> = gate.qubits.iter() - .map(|q| q.index()).collect(); + let qubits: SmallVec<[usize; 4]> = + gate.qubits.iter().map(pecos_core::QubitId::index).collect(); let injections = noise.noise_after_gate(i, gate.gate_type, &qubits); if injections.is_empty() { @@ -93,40 +125,47 @@ pub fn build_noise_map( // We compute a combined scale factor for each support pattern. let mut s_rates_q0_only = Vec::new(); // S noise on q0 only let mut s_rates_q1_only = Vec::new(); // S noise on q1 only - let mut s_rates_both = Vec::new(); // S noise on both q0 and q1 - let mut s_rates_other = Vec::new(); // S noise on other patterns + let mut s_rates_both = Vec::new(); // S noise on both q0 and q1 + let mut s_rates_other = Vec::new(); // S noise on other patterns let q0 = qubits.first().copied().unwrap_or(0) as u16; - let q1 = if qubits.len() >= 2 { qubits[1] as u16 } else { q0 }; + let q1 = if qubits.len() >= 2 { + qubits[1] as u16 + } else { + q0 + }; for inj in &injections { - match inj.eeg_type { - crate::eeg::EegType::H => { h_inj.push(inj.clone()); } - crate::eeg::EegType::S => { - let rate = inj.rate; - // Classify by qubit support - let on_q0 = inj.label.has_x(q0 as usize) || inj.label.has_z(q0 as usize); - let on_q1 = qubits.len() >= 2 - && (inj.label.has_x(q1 as usize) || inj.label.has_z(q1 as usize)); - - // For each S injection with rate s (s < 0), the scale for - // anticommuting terms is (1 - 2*(-s)) = (1 + 2s). - // We need to count how many of the term's components - // anticommute. For a uniform depolarizing model this is - // predetermined by the support pattern. - // - // Instead of trying to batch analytically (which requires - // knowing the exact anticommutation count), we accumulate - // the log of the scale factors and compute the combined - // scale per support pattern. - // - // For now, just collect individual rates. - if on_q0 && !on_q1 { s_rates_q0_only.push(rate); } - else if !on_q0 && on_q1 { s_rates_q1_only.push(rate); } - else if on_q0 && on_q1 { s_rates_both.push(rate); } - else { s_rates_other.push(rate); } + if inj.eeg_type == crate::eeg::EegType::S { + let rate = inj.rate; + // Classify by qubit support + let on_q0 = inj.label.has_x(q0 as usize) || inj.label.has_z(q0 as usize); + let on_q1 = qubits.len() >= 2 + && (inj.label.has_x(q1 as usize) || inj.label.has_z(q1 as usize)); + + // For each S injection with rate s (s < 0), the scale for + // anticommuting terms is (1 - 2*(-s)) = (1 + 2s). + // We need to count how many of the term's components + // anticommute. For a uniform depolarizing model this is + // predetermined by the support pattern. + // + // Instead of trying to batch analytically (which requires + // knowing the exact anticommutation count), we accumulate + // the log of the scale factors and compute the combined + // scale per support pattern. + // + // For now, just collect individual rates. + if on_q0 && !on_q1 { + s_rates_q0_only.push(rate); + } else if !on_q0 && on_q1 { + s_rates_q1_only.push(rate); + } else if on_q0 && on_q1 { + s_rates_both.push(rate); + } else { + s_rates_other.push(rate); } - _ => { h_inj.push(inj.clone()); } + } else { + h_inj.push(inj.clone()); } } @@ -144,11 +183,13 @@ pub fn build_noise_map( // Optimization: if ALL S rates are the same (uniform depol), use // closed-form. Otherwise, keep individual injections. let all_s_same_rate = { - let all_s: Vec = s_rates_q0_only.iter() + let all_s: Vec = s_rates_q0_only + .iter() .chain(&s_rates_q1_only) .chain(&s_rates_both) .chain(&s_rates_other) - .copied().collect(); + .copied() + .collect(); !all_s.is_empty() && all_s.iter().all(|&r| (r - all_s[0]).abs() < 1e-20) }; @@ -158,10 +199,12 @@ pub fn build_noise_map( // For single-qubit: 3 S generators, 2 anticommute → scale = (1+2s)^2 // For two-qubit: 15 S generators, 8 anticommute for any non-trivial → (1+2s)^8 let total_s = s_rates_q0_only.len() + s_rates_q1_only.len() + s_rates_both.len(); - let s = s_rates_q0_only.first() + let s = s_rates_q0_only + .first() .or(s_rates_q1_only.first()) .or(s_rates_both.first()) - .copied().unwrap_or(0.0); + .copied() + .unwrap_or(0.0); let p = -s; let individual_scale = 1.0 - 2.0 * p; @@ -181,7 +224,13 @@ pub fn build_noise_map( // Actually, let me just precompute this properly. // For 1q depol (3 generators): non-identity on q → 2 anticommute → (1-2p/3)^2 // For 2q depol (15 generators): non-identity on either q → 8 anticommute → (1-2p/15)^8 - let n_anti = if total_s == 3 { 2 } else if total_s == 15 { 8 } else { 0 }; + let n_anti = if total_s == 3 { + 2 + } else if total_s == 15 { + 8 + } else { + 0 + }; if n_anti == 0 && total_s > 0 { // Non-standard S count (e.g., 1 for p_meas, 1 for p_prep): // can't batch — put in h_injections for individual processing. @@ -202,8 +251,10 @@ pub fn build_noise_map( both_scale: combined, num_gate_qubits: qubits.len().min(2) as u8, })); - } else if s_rates_q0_only.is_empty() && s_rates_q1_only.is_empty() - && s_rates_both.is_empty() && s_rates_other.is_empty() + } else if s_rates_q0_only.is_empty() + && s_rates_q1_only.is_empty() + && s_rates_both.is_empty() + && s_rates_other.is_empty() { // H-type only, no S noise if h_inj.is_empty() { @@ -211,7 +262,11 @@ pub fn build_noise_map( } else { map.push(Some(PrecomputedGateNoise { h_injections: h_inj, - q0_scale: 1.0, q0, q1_scale: 1.0, q1, both_scale: 1.0, + q0_scale: 1.0, + q0, + q1_scale: 1.0, + q1, + both_scale: 1.0, num_gate_qubits: qubits.len().min(2) as u8, })); } @@ -225,7 +280,11 @@ pub fn build_noise_map( } map.push(Some(PrecomputedGateNoise { h_injections: h_inj, - q0_scale: 1.0, q0, q1_scale: 1.0, q1, both_scale: 1.0, + q0_scale: 1.0, + q0, + q1_scale: 1.0, + q1, + both_scale: 1.0, num_gate_qubits: qubits.len().min(2) as u8, })); } @@ -253,16 +312,24 @@ impl SparsePauli { let max_z = bm.z_bits.highest_set_bit().unwrap_or(0); let max_q = max_x.max(max_z); for q in 0..=max_q { - if bm.has_x(q) { sp.x_qubits.push(q as u16); } - if bm.has_z(q) { sp.z_qubits.push(q as u16); } + if bm.has_x(q) { + sp.x_qubits.push(q as u16); + } + if bm.has_z(q) { + sp.z_qubits.push(q as u16); + } } sp } pub(crate) fn to_bm(&self) -> Bm { let mut bm = Bm::default(); - for &q in &self.x_qubits { bm.x_bits.set_bit(q as usize); } - for &q in &self.z_qubits { bm.z_bits.set_bit(q as usize); } + for &q in &self.x_qubits { + bm.x_bits.set_bit(q as usize); + } + for &q in &self.z_qubits { + bm.z_bits.set_bit(q as usize); + } bm } @@ -284,15 +351,23 @@ impl SparsePauli { /// Toggle x-bit at qubit q (insert if missing, remove if present). fn toggle_x(&mut self, q: u16) { match self.x_qubits.binary_search(&q) { - Ok(i) => { self.x_qubits.remove(i); } - Err(i) => { self.x_qubits.insert(i, q); } + Ok(i) => { + self.x_qubits.remove(i); + } + Err(i) => { + self.x_qubits.insert(i, q); + } } } fn toggle_z(&mut self, q: u16) { match self.z_qubits.binary_search(&q) { - Ok(i) => { self.z_qubits.remove(i); } - Err(i) => { self.z_qubits.insert(i, q); } + Ok(i) => { + self.z_qubits.remove(i); + } + Err(i) => { + self.z_qubits.insert(i, q); + } } } @@ -317,7 +392,7 @@ impl SparsePauli { // Commutes iff count is even. let c1 = sorted_intersection_count(&self.x_qubits, &other.z_qubits); let c2 = sorted_intersection_count(&self.z_qubits, &other.x_qubits); - (c1 + c2) % 2 == 0 + (c1 + c2).is_multiple_of(2) } } @@ -337,12 +412,16 @@ impl std::hash::Hash for SparsePauli { impl Ord for SparsePauli { fn cmp(&self, other: &Self) -> std::cmp::Ordering { - self.x_qubits.as_slice().cmp(other.x_qubits.as_slice()) + self.x_qubits + .as_slice() + .cmp(other.x_qubits.as_slice()) .then(self.z_qubits.as_slice().cmp(other.z_qubits.as_slice())) } } impl PartialOrd for SparsePauli { - fn partial_cmp(&self, other: &Self) -> Option { Some(self.cmp(other)) } + fn partial_cmp(&self, other: &Self) -> Option { + Some(self.cmp(other)) + } } /// Count elements in the intersection of two sorted slices. @@ -354,7 +433,11 @@ fn sorted_intersection_count(a: &[u16], b: &[u16]) -> u32 { match a[i].cmp(&b[j]) { std::cmp::Ordering::Less => i += 1, std::cmp::Ordering::Greater => j += 1, - std::cmp::Ordering::Equal => { count += 1; i += 1; j += 1; } + std::cmp::Ordering::Equal => { + count += 1; + i += 1; + j += 1; + } } } count @@ -380,16 +463,17 @@ impl SparsePauli { let cz = self.has_z(c); let tx = self.has_x(t); let tz = self.has_z(t); - if cx { self.toggle_x(t); } - if tz { self.toggle_z(c); } + if cx { + self.toggle_x(t); + } + if tz { + self.toggle_z(c); + } // Sign from phase table (same formula as the fixed conjugate_cx) - const PHASE: [[u8; 4]; 4] = [ - [0, 0, 0, 0], [0, 0, 3, 1], [0, 1, 0, 3], [0, 3, 1, 0], - ]; - let pc = (cx as u8) + 2 * (cz as u8); - let pt = (tx as u8) + 2 * (tz as u8); - let phase_c = if tz { PHASE[pc as usize][2] } else { 0 }; - let phase_t = if cx { PHASE[1][pt as usize] } else { 0 }; + let pc = u8::from(cx) + 2 * u8::from(cz); + let pt = u8::from(tx) + 2 * u8::from(tz); + let phase_c = if tz { CX_PHASE[pc as usize][2] } else { 0 }; + let phase_t = if cx { CX_PHASE[1][pt as usize] } else { 0 }; (phase_c + phase_t) % 4 == 2 } @@ -399,21 +483,33 @@ impl SparsePauli { let bx = self.has_x(b); let az = self.has_z(a); let bz = self.has_z(b); - if bx { self.toggle_z(a); } - if ax { self.toggle_z(b); } + if bx { + self.toggle_z(a); + } + if ax { + self.toggle_z(b); + } ax && bx && (az != bz) } /// Conjugate by Pauli X on qubit q. - fn conjugate_pauli_x(&self, q: u16) -> bool { self.has_z(q) } + fn conjugate_pauli_x(&self, q: u16) -> bool { + self.has_z(q) + } /// Conjugate by Pauli Y on qubit q. - fn conjugate_pauli_y(&self, q: u16) -> bool { self.has_x(q) != self.has_z(q) } + fn conjugate_pauli_y(&self, q: u16) -> bool { + self.has_x(q) != self.has_z(q) + } /// Conjugate by Pauli Z on qubit q. - fn conjugate_pauli_z(&self, q: u16) -> bool { self.has_x(q) } + fn conjugate_pauli_z(&self, q: u16) -> bool { + self.has_x(q) + } /// Conjugate by SZ on qubit q: X→Y, Y→-X, Z→Z. fn conjugate_sz(&mut self, q: u16) -> bool { - if !self.has_x(q) { return false; } + if !self.has_x(q) { + return false; + } let was_y = self.has_z(q); self.toggle_z(q); was_y @@ -421,7 +517,9 @@ impl SparsePauli { /// Conjugate by SZdg on qubit q. fn conjugate_szdg(&mut self, q: u16) -> bool { - if !self.has_x(q) { return false; } + if !self.has_x(q) { + return false; + } let was_y = self.has_z(q); self.toggle_z(q); !was_y @@ -431,7 +529,9 @@ impl SparsePauli { fn conjugate_sx(&mut self, q: u16) -> bool { let xq = self.has_x(q); let zq = self.has_z(q); - if zq { self.toggle_x(q); } + if zq { + self.toggle_x(q); + } !xq && zq } @@ -439,7 +539,9 @@ impl SparsePauli { fn conjugate_sxdg(&mut self, q: u16) -> bool { let xq = self.has_x(q); let zq = self.has_z(q); - if zq { self.toggle_x(q); } + if zq { + self.toggle_x(q); + } xq && zq } @@ -467,14 +569,36 @@ impl SparsePauli { /// Conjugate by SWAP(a, b). fn conjugate_swap(&mut self, a: u16, b: u16) { - let ax = self.has_x(a); let az = self.has_z(a); - let bx = self.has_x(b); let bz = self.has_z(b); + let ax = self.has_x(a); + let az = self.has_z(a); + let bx = self.has_x(b); + let bz = self.has_z(b); // Clear both - if ax { self.clear_x(a); } if az { self.clear_z(a); } - if bx { self.clear_x(b); } if bz { self.clear_z(b); } + if ax { + self.clear_x(a); + } + if az { + self.clear_z(a); + } + if bx { + self.clear_x(b); + } + if bz { + self.clear_z(b); + } // Set swapped - if bx { self.toggle_x(a); } if bz { self.toggle_z(a); } - if ax { self.toggle_x(b); } if az { self.toggle_z(b); } + if bx { + self.toggle_x(a); + } + if bz { + self.toggle_z(a); + } + if ax { + self.toggle_x(b); + } + if az { + self.toggle_z(b); + } } } @@ -485,7 +609,9 @@ impl SparsePauli { /// to their adjoints: SZ↔SZdg, SX↔SXdg, SY↔SYdg, SZZ↔SZZdg, etc. /// Self-adjoint gates (H, X, Y, Z, CX, CZ, SWAP, CY) are unchanged. pub(crate) fn sparse_conjugate(p: &mut SparsePauli, gate: &Gate) -> Option { - if gate.qubits.is_empty() { return None; } + if gate.qubits.is_empty() { + return None; + } let q0 = gate.qubits[0].index() as u16; match gate.gate_type { // Self-adjoint single-qubit gates @@ -501,16 +627,26 @@ pub(crate) fn sparse_conjugate(p: &mut SparsePauli, gate: &Gate) -> Option GateType::SY => Some(p.conjugate_sydg(q0)), GateType::SYdg => Some(p.conjugate_sy(q0)), // Self-adjoint two-qubit gates - GateType::CX => { let q1 = gate.qubits[1].index() as u16; Some(p.conjugate_cx(q0, q1)) } - GateType::CZ => { let q1 = gate.qubits[1].index() as u16; Some(p.conjugate_cz(q0, q1)) } - GateType::SWAP => { let q1 = gate.qubits[1].index() as u16; p.conjugate_swap(q0, q1); Some(false) } + GateType::CX => { + let q1 = gate.qubits[1].index() as u16; + Some(p.conjugate_cx(q0, q1)) + } + GateType::CZ => { + let q1 = gate.qubits[1].index() as u16; + Some(p.conjugate_cz(q0, q1)) + } + GateType::SWAP => { + let q1 = gate.qubits[1].index() as u16; + p.conjugate_swap(q0, q1); + Some(false) + } // CY is self-adjoint: CY = SZdg(t) CX(c,t) SZ(t) — chain GateType::CY => { let q1 = gate.qubits[1].index() as u16; let s1 = p.conjugate_sz(q1); let s2 = p.conjugate_cx(q0, q1); let s3 = p.conjugate_szdg(q1); - Some((s1 as u8 + s2 as u8 + s3 as u8) % 2 == 1) + Some(sign_parity([s1, s2, s3])) } // Non-self-adjoint two-qubit: swap to adjoint for backward. // SZZ backward = SZZdg forward = CX(q0,q1) SZdg(q1) CX(q0,q1) @@ -519,7 +655,7 @@ pub(crate) fn sparse_conjugate(p: &mut SparsePauli, gate: &Gate) -> Option let s1 = p.conjugate_cx(q0, q1); let s2 = p.conjugate_szdg(q1); let s3 = p.conjugate_cx(q0, q1); - Some((s1 as u8 + s2 as u8 + s3 as u8) % 2 == 1) + Some(sign_parity([s1, s2, s3])) } // SZZdg backward = SZZ forward = CX(q0,q1) SZ(q1) CX(q0,q1) GateType::SZZdg => { @@ -527,7 +663,7 @@ pub(crate) fn sparse_conjugate(p: &mut SparsePauli, gate: &Gate) -> Option let s1 = p.conjugate_cx(q0, q1); let s2 = p.conjugate_sz(q1); let s3 = p.conjugate_cx(q0, q1); - Some((s1 as u8 + s2 as u8 + s3 as u8) % 2 == 1) + Some(sign_parity([s1, s2, s3])) } // SXX backward = SXXdg forward = H(q0) H(q1) SZZdg H(q0) H(q1) GateType::SXX => { @@ -539,8 +675,7 @@ pub(crate) fn sparse_conjugate(p: &mut SparsePauli, gate: &Gate) -> Option let s5 = p.conjugate_cx(q0, q1); let s6 = p.conjugate_h(q0); let s7 = p.conjugate_h(q1); - let total = s1 as u8 + s2 as u8 + s3 as u8 + s4 as u8 + s5 as u8 + s6 as u8 + s7 as u8; - Some(total % 2 == 1) + Some(sign_parity([s1, s2, s3, s4, s5, s6, s7])) } // SXXdg backward = SXX forward GateType::SXXdg => { @@ -552,8 +687,7 @@ pub(crate) fn sparse_conjugate(p: &mut SparsePauli, gate: &Gate) -> Option let s5 = p.conjugate_cx(q0, q1); let s6 = p.conjugate_h(q0); let s7 = p.conjugate_h(q1); - let total = s1 as u8 + s2 as u8 + s3 as u8 + s4 as u8 + s5 as u8 + s6 as u8 + s7 as u8; - Some(total % 2 == 1) + Some(sign_parity([s1, s2, s3, s4, s5, s6, s7])) } // SYY backward = SYYdg forward = SX(q0) SX(q1) SZZdg SXdg(q0) SXdg(q1) GateType::SYY => { @@ -565,8 +699,7 @@ pub(crate) fn sparse_conjugate(p: &mut SparsePauli, gate: &Gate) -> Option let s5 = p.conjugate_cx(q0, q1); let s6 = p.conjugate_sx(q0); let s7 = p.conjugate_sx(q1); - let total = s1 as u8 + s2 as u8 + s3 as u8 + s4 as u8 + s5 as u8 + s6 as u8 + s7 as u8; - Some(total % 2 == 1) + Some(sign_parity([s1, s2, s3, s4, s5, s6, s7])) } // SYYdg backward = SYY forward GateType::SYYdg => { @@ -578,13 +711,17 @@ pub(crate) fn sparse_conjugate(p: &mut SparsePauli, gate: &Gate) -> Option let s5 = p.conjugate_cx(q0, q1); let s6 = p.conjugate_sxdg(q0); let s7 = p.conjugate_sxdg(q1); - let total = s1 as u8 + s2 as u8 + s3 as u8 + s4 as u8 + s5 as u8 + s6 as u8 + s7 as u8; - Some(total % 2 == 1) + Some(sign_parity([s1, s2, s3, s4, s5, s6, s7])) } // Gates that don't conjugate Paulis - GateType::PZ | GateType::QAlloc | GateType::QFree - | GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked - | GateType::I | GateType::Idle => None, + GateType::PZ + | GateType::QAlloc + | GateType::QFree + | GateType::MZ + | GateType::MeasureFree + | GateType::MeasureLeaked + | GateType::I + | GateType::Idle => None, other => panic!("EEG Heisenberg: unsupported gate type {other:?}"), } } @@ -641,14 +778,23 @@ pub fn heisenberg_with_noise_map( }]; // Conservative active-qubit bitmap - let max_qubit = gates.iter() + let max_qubit = gates + .iter() .flat_map(|g| g.qubits.iter()) - .map(|q| q.index()) + .map(pecos_core::QubitId::index) .max() - .unwrap_or(0) + 1; + .unwrap_or(0) + + 1; let mut active_qubits = vec![false; max_qubit]; - for &q in terms[0].pauli.x_qubits.iter().chain(terms[0].pauli.z_qubits.iter()) { - if (q as usize) < active_qubits.len() { active_qubits[q as usize] = true; } + for &q in terms[0] + .pauli + .x_qubits + .iter() + .chain(terms[0].pauli.z_qubits.iter()) + { + if (q as usize) < active_qubits.len() { + active_qubits[q as usize] = true; + } } let mut last_merge_count = 1usize; @@ -656,14 +802,18 @@ pub fn heisenberg_with_noise_map( for i in (0..gates.len()).rev() { let gate = &gates[i]; - let gate_qs: SmallVec<[u16; 4]> = gate.qubits.iter() - .map(|q| q.index() as u16).collect(); + let gate_qs: SmallVec<[u16; 4]> = gate.qubits.iter().map(|q| q.index() as u16).collect(); - let gate_touches_active = gate_qs.iter() + let gate_touches_active = gate_qs + .iter() .any(|&q| (q as usize) < active_qubits.len() && active_qubits[q as usize]); // Look up precomputed noise for this gate - let gate_noise = if gate_touches_active { noise_map.get(i).and_then(|n| n.as_ref()) } else { None }; + let gate_noise = if gate_touches_active { + noise_map.get(i).and_then(|n| n.as_ref()) + } else { + None + }; if let Some(gn) = gate_noise { // H-type injections (branching) @@ -671,47 +821,64 @@ pub fn heisenberg_with_noise_map( match inj.eeg_type { crate::eeg::EegType::H => { let h = inj.rate; - if h.abs() < 1e-20 { continue; } + if h.abs() < 1e-20 { + continue; + } let cos2h = (2.0 * h).cos(); let sin2h = (2.0 * h).sin(); let single_z_qubit: Option = if inj.label.x_bits.is_zero() { inj.label.z_bits.highest_set_bit().map(|q| q as u16) - } else { None }; + } else { + None + }; let noise_sparse = if single_z_qubit.is_none() { Some(SparsePauli::from_bm(&inj.label)) - } else { None }; + } else { + None + }; sin_branches.clear(); let n = terms.len(); - for idx in 0..n { + for term in terms.iter_mut().take(n) { let anticommutes = if let Some(q) = single_z_qubit { - terms[idx].pauli.has_x(q) + term.pauli.has_x(q) } else { - !terms[idx].pauli.commutes_with(noise_sparse.as_ref().unwrap()) + !term.pauli.commutes_with(noise_sparse.as_ref().unwrap()) }; if anticommutes { - let (sr, si) = (sin2h * terms[idx].coeff_re, sin2h * terms[idx].coeff_im); + let (sr, si) = (sin2h * term.coeff_re, sin2h * term.coeff_im); let (dp, total_phase) = if let Some(q) = single_z_qubit { - let mut dp = terms[idx].pauli.clone(); + let mut dp = term.pauli.clone(); dp.toggle_z(q); - let has_x = terms[idx].pauli.has_x(q); - let has_z = terms[idx].pauli.has_z(q); - let phase = if has_x { if has_z { 3u8 } else { 1 } } else { 0 }; + let has_x = term.pauli.has_x(q); + let has_z = term.pauli.has_z(q); + let phase = if has_x { + if has_z { 3u8 } else { 1 } + } else { + 0 + }; (dp, (phase + 1) % 4) } else { - let term_bm = terms[idx].pauli.to_bm(); - let (dp_bm, phase_exp) = inj.label.multiply_with_phase(&term_bm); + let term_bm = term.pauli.to_bm(); + let (dp_bm, phase_exp) = + inj.label.multiply_with_phase(&term_bm); (SparsePauli::from_bm(&dp_bm), (phase_exp + 1) % 4) }; let (new_re, new_im) = match total_phase { - 0 => (sr, si), 1 => (-si, sr), - 2 => (-sr, -si), 3 => (si, -sr), + 0 => (sr, si), + 1 => (-si, sr), + 2 => (-sr, -si), + 3 => (si, -sr), _ => unreachable!(), }; - sin_branches.push(HeisenbergTerm { pauli: dp, coeff_re: new_re, coeff_im: new_im }); - terms[idx].coeff_re *= cos2h; - terms[idx].coeff_im *= cos2h; + sin_branches.push(HeisenbergTerm { + pauli: dp, + coeff_re: new_re, + coeff_im: new_im, + }); + term.coeff_re *= cos2h; + term.coeff_im *= cos2h; } } // Merge sin branches: try binary search merge if terms @@ -719,16 +886,19 @@ pub fn heisenberg_with_noise_map( for t in sin_branches.drain(..) { for &q in t.pauli.x_qubits.iter().chain(t.pauli.z_qubits.iter()) { let qu = q as usize; - if qu < active_qubits.len() { active_qubits[qu] = true; } + if qu < active_qubits.len() { + active_qubits[qu] = true; + } } if last_merge_count == terms.len() { match terms.binary_search_by(|p| p.pauli.cmp(&t.pauli)) { Ok(idx) => { terms[idx].coeff_re += t.coeff_re; terms[idx].coeff_im += t.coeff_im; - continue; } - Err(_) => { terms.push(t); } + Err(_) => { + terms.push(t); + } } } else { terms.push(t); @@ -738,7 +908,9 @@ pub fn heisenberg_with_noise_map( crate::eeg::EegType::S => { // Non-batched S-type (fallback for non-uniform noise) let s = inj.rate; - if s.abs() < 1e-20 { continue; } + if s.abs() < 1e-20 { + continue; + } let p = -s; let scale = 1.0 - 2.0 * p; let single_q: Option = { @@ -757,13 +929,17 @@ pub fn heisenberg_with_noise_map( for term in &mut terms { let anti = (has_z_in_noise && term.pauli.has_x(q)) || (has_x_in_noise && term.pauli.has_z(q)); - if anti { term.coeff_re *= scale; term.coeff_im *= scale; } + if anti { + term.coeff_re *= scale; + term.coeff_im *= scale; + } } } else { let ns = SparsePauli::from_bm(&inj.label); for term in &mut terms { if !term.pauli.commutes_with(&ns) { - term.coeff_re *= scale; term.coeff_im *= scale; + term.coeff_re *= scale; + term.coeff_im *= scale; } } } @@ -803,13 +979,17 @@ pub fn heisenberg_with_noise_map( } // Step 2: Backward Clifford conjugation - if !gate_touches_active { continue; } + if !gate_touches_active { + continue; + } match gate.gate_type { GateType::PZ | GateType::QAlloc => { terms.retain(|t| !gate_qs.iter().any(|&qi| t.pauli.has_x(qi))); for t in &mut terms { - for &qi in &gate_qs { t.pauli.clear_z(qi); } + for &qi in &gate_qs { + t.pauli.clear_z(qi); + } } } GateType::MZ => { @@ -817,12 +997,17 @@ pub fn heisenberg_with_noise_map( } _ => { for t in &mut terms { - if let Some(sign_neg) = sparse_conjugate(&mut t.pauli, gate) { - if sign_neg { t.coeff_re = -t.coeff_re; t.coeff_im = -t.coeff_im; } + if let Some(sign_neg) = sparse_conjugate(&mut t.pauli, gate) + && sign_neg + { + t.coeff_re = -t.coeff_re; + t.coeff_im = -t.coeff_im; } for &q in t.pauli.x_qubits.iter().chain(t.pauli.z_qubits.iter()) { let qu = q as usize; - if qu < active_qubits.len() { active_qubits[qu] = true; } + if qu < active_qubits.len() { + active_qubits[qu] = true; + } } } } @@ -852,12 +1037,20 @@ pub fn heisenberg_with_noise_map( if terms[write].coeff_re.abs() > 1e-30 || terms[write].coeff_im.abs() > 1e-30 { write += 1; } - if write < read { terms.swap(write, read); } + if write < read { + terms.swap(write, read); + } } } let final_len = if !terms.is_empty() && (terms[write].coeff_re.abs() > 1e-30 || terms[write].coeff_im.abs() > 1e-30) - { write + 1 } else if terms.is_empty() { 0 } else { write }; + { + write + 1 + } else if terms.is_empty() { + 0 + } else { + write + }; terms.truncate(final_len); last_merge_count = terms.len().max(1); } @@ -866,15 +1059,19 @@ pub fn heisenberg_with_noise_map( // Evaluate let mut expectation_re = 0.0; for term in &terms { - let eigenvalue = if term.pauli.is_identity() { 1.0 } else { + let eigenvalue = if term.pauli.is_identity() { + 1.0 + } else { let bm = term.pauli.to_bm(); match initial_stab.is_stabilizer(&bm) { - Some(true) => 1.0, Some(false) => -1.0, None => 0.0, + Some(true) => 1.0, + Some(false) => -1.0, + None => 0.0, } }; expectation_re += term.coeff_re * eigenvalue; } - (0.5 * (1.0 - expectation_re)).max(0.0).min(1.0) + (0.5 * (1.0 - expectation_re)).clamp(0.0, 1.0) } /// Backward Heisenberg with optional gate windowing. @@ -900,16 +1097,22 @@ pub fn heisenberg_windowed( // Identify expansion gates (virtual, no physical noise). let expansion_gates = { let mut exp = vec![false; gates.len()]; - if !gates.is_empty() && gates[0].gate_type == GateType::QAlloc { exp[0] = true; } + if !gates.is_empty() && gates[0].gate_type == GateType::QAlloc { + exp[0] = true; + } for i in 1..gates.len() { - if gates[i].gate_type == GateType::QAlloc { exp[i] = true; } - if gates[i].gate_type == GateType::CX && gates[i-1].gate_type == GateType::QAlloc { - let aq = gates[i-1].qubits[0].index(); + if gates[i].gate_type == GateType::QAlloc { + exp[i] = true; + } + if gates[i].gate_type == GateType::CX && gates[i - 1].gate_type == GateType::QAlloc { + let aq = gates[i - 1].qubits[0].index(); if gates[i].qubits.len() >= 2 && gates[i].qubits[1].index() == aq { exp[i] = true; - if i+1 < gates.len() && gates[i+1].gate_type == GateType::PZ - && gates[i+1].qubits[0].index() == gates[i].qubits[0].index() { - exp[i+1] = true; + if i + 1 < gates.len() + && gates[i + 1].gate_type == GateType::PZ + && gates[i + 1].qubits[0].index() == gates[i].qubits[0].index() + { + exp[i + 1] = true; } } } @@ -923,14 +1126,21 @@ pub fn heisenberg_windowed( // Conservative active-qubit bitmap: once a qubit is active, stays active. // This avoids the expensive per-term scan for gate relevance. - let max_qubit = gates.iter() + let max_qubit = gates + .iter() .flat_map(|g| g.qubits.iter()) - .map(|q| q.index()) + .map(pecos_core::QubitId::index) .max() - .unwrap_or(0) + 1; + .unwrap_or(0) + + 1; let mut active_qubits = vec![false; max_qubit]; // Seed from detector - for &q in terms[0].pauli.x_qubits.iter().chain(terms[0].pauli.z_qubits.iter()) { + for &q in terms[0] + .pauli + .x_qubits + .iter() + .chain(terms[0].pauli.z_qubits.iter()) + { if (q as usize) < active_qubits.len() { active_qubits[q as usize] = true; } @@ -940,24 +1150,25 @@ pub fn heisenberg_windowed( let (walk_start, walk_end) = gate_window.unwrap_or((0, gates.len())); for i in (walk_start..walk_end).rev() { let gate = &gates[i]; - let gate_qs: SmallVec<[u16; 4]> = gate.qubits.iter() - .map(|q| q.index() as u16).collect(); + let gate_qs: SmallVec<[u16; 4]> = gate.qubits.iter().map(|q| q.index() as u16).collect(); // O(1) gate relevance check via bitmap (conservative: may visit some extra gates) - let gate_touches_active = gate_qs.iter() + let gate_touches_active = gate_qs + .iter() .any(|&q| (q as usize) < active_qubits.len() && active_qubits[q as usize]); // Step 1: Apply noise adjoint (skip expansion gates). if !expansion_gates[i] && gate_touches_active { - let qubits_usize: SmallVec<[usize; 4]> = gate_qs.iter() - .map(|&q| q as usize).collect(); + let qubits_usize: SmallVec<[usize; 4]> = gate_qs.iter().map(|&q| q as usize).collect(); let injections = noise.noise_after_gate(i, gate.gate_type, &qubits_usize); for inj in &injections { match inj.eeg_type { crate::eeg::EegType::H => { let h = inj.rate; - if h.abs() < 1e-20 { continue; } + if h.abs() < 1e-20 { + continue; + } let cos2h = (2.0 * h).cos(); let sin2h = (2.0 * h).sin(); @@ -977,26 +1188,29 @@ pub fn heisenberg_windowed( sin_branches.clear(); let n = terms.len(); - for idx in 0..n { + for term in terms.iter_mut().take(n) { let anticommutes = if let Some(q) = single_z_qubit { - terms[idx].pauli.has_x(q) + term.pauli.has_x(q) } else { - !terms[idx].pauli.commutes_with(noise_sparse.as_ref().unwrap()) + !term.pauli.commutes_with(noise_sparse.as_ref().unwrap()) }; if anticommutes { - let (sr, si) = - (sin2h * terms[idx].coeff_re, sin2h * terms[idx].coeff_im); + let (sr, si) = (sin2h * term.coeff_re, sin2h * term.coeff_im); let (dp, total_phase) = if let Some(q) = single_z_qubit { - let mut dp = terms[idx].pauli.clone(); + let mut dp = term.pauli.clone(); dp.toggle_z(q); - let has_x = terms[idx].pauli.has_x(q); - let has_z = terms[idx].pauli.has_z(q); - let phase = if has_x { if has_z { 3u8 } else { 1 } } else { 0 }; + let has_x = term.pauli.has_x(q); + let has_z = term.pauli.has_z(q); + let phase = if has_x { + if has_z { 3u8 } else { 1 } + } else { + 0 + }; (dp, (phase + 1) % 4) } else { - let term_bm = terms[idx].pauli.to_bm(); + let term_bm = term.pauli.to_bm(); let (dp_bm, phase_exp) = inj.label.multiply_with_phase(&term_bm); (SparsePauli::from_bm(&dp_bm), (phase_exp + 1) % 4) @@ -1010,10 +1224,12 @@ pub fn heisenberg_windowed( _ => unreachable!(), }; sin_branches.push(HeisenbergTerm { - pauli: dp, coeff_re: new_re, coeff_im: new_im, + pauli: dp, + coeff_re: new_re, + coeff_im: new_im, }); - terms[idx].coeff_re *= cos2h; - terms[idx].coeff_im *= cos2h; + term.coeff_re *= cos2h; + term.coeff_im *= cos2h; } } @@ -1021,14 +1237,18 @@ pub fn heisenberg_windowed( for t in &sin_branches { for &q in t.pauli.x_qubits.iter().chain(t.pauli.z_qubits.iter()) { let qu = q as usize; - if qu < active_qubits.len() { active_qubits[qu] = true; } + if qu < active_qubits.len() { + active_qubits[qu] = true; + } } } - terms.extend(sin_branches.drain(..)); + terms.append(&mut sin_branches); } crate::eeg::EegType::S => { let s = inj.rate; - if s.abs() < 1e-20 { continue; } + if s.abs() < 1e-20 { + continue; + } let p = -s; let scale = 1.0 - 2.0 * p; // For S-type, single-qubit specialization @@ -1087,9 +1307,7 @@ pub fn heisenberg_windowed( match gate.gate_type { // #4: Batch PZ/QAlloc — single pass through terms for all qubits GateType::PZ | GateType::QAlloc => { - terms.retain(|t| { - !gate_qs.iter().any(|&qi| t.pauli.has_x(qi)) - }); + terms.retain(|t| !gate_qs.iter().any(|&qi| t.pauli.has_x(qi))); for t in &mut terms { for &qi in &gate_qs { t.pauli.clear_z(qi); @@ -1097,22 +1315,22 @@ pub fn heisenberg_windowed( } } GateType::MZ => { - terms.retain(|t| { - !gate_qs.iter().any(|&qi| t.pauli.has_x(qi)) - }); + terms.retain(|t| !gate_qs.iter().any(|&qi| t.pauli.has_x(qi))); } _ => { for t in &mut terms { - if let Some(sign_neg) = sparse_conjugate(&mut t.pauli, gate) { - if sign_neg { - t.coeff_re = -t.coeff_re; - t.coeff_im = -t.coeff_im; - } + if let Some(sign_neg) = sparse_conjugate(&mut t.pauli, gate) + && sign_neg + { + t.coeff_re = -t.coeff_re; + t.coeff_im = -t.coeff_im; } // Update active bitmap (CX can spread support to new qubits) for &q in t.pauli.x_qubits.iter().chain(t.pauli.z_qubits.iter()) { let qu = q as usize; - if qu < active_qubits.len() { active_qubits[qu] = true; } + if qu < active_qubits.len() { + active_qubits[qu] = true; + } } } } @@ -1133,9 +1351,7 @@ pub fn heisenberg_windowed( terms[write].coeff_re += re; terms[write].coeff_im += im; } else { - if terms[write].coeff_re.abs() > 1e-30 - || terms[write].coeff_im.abs() > 1e-30 - { + if terms[write].coeff_re.abs() > 1e-30 || terms[write].coeff_im.abs() > 1e-30 { write += 1; } if write < read { @@ -1143,13 +1359,12 @@ pub fn heisenberg_windowed( } } } - let final_len = if terms[write].coeff_re.abs() > 1e-30 - || terms[write].coeff_im.abs() > 1e-30 - { - write + 1 - } else { - write - }; + let final_len = + if terms[write].coeff_re.abs() > 1e-30 || terms[write].coeff_im.abs() > 1e-30 { + write + 1 + } else { + write + }; terms.truncate(final_len); last_merge_count = terms.len().max(1); } @@ -1175,7 +1390,7 @@ pub fn heisenberg_windowed( } let prob = 0.5 * (1.0 - expectation_re); - prob.max(0.0).min(1.0) + prob.clamp(0.0, 1.0) } /// Backward Heisenberg with sparse gate traversal via precomputed index. @@ -1198,8 +1413,6 @@ pub fn heisenberg_sparse( gate_index: &crate::expand::GateIndex, noise_map: Option<&[Option]>, ) -> f64 { - use std::collections::BinaryHeap; - let mut terms = vec![HeisenbergTerm { pauli: SparsePauli::from_bm(detector), coeff_re: 1.0, @@ -1218,36 +1431,27 @@ pub fn heisenberg_sparse( // Max-heap: pops largest gate index first (backward traversal). let mut heap: BinaryHeap = BinaryHeap::new(); - // Add gates on qubit q that are BEFORE `before_gate` (index < before_gate) to the heap. - // Gates at or after before_gate have already been passed in the backward walk. - fn activate_qubit( - q: u16, - before_gate: u32, - active: &mut [bool], - visited: &mut [bool], - heap: &mut BinaryHeap, - gate_index: &crate::expand::GateIndex, - ) { - let qu = q as usize; - if qu >= active.len() { return; } - active[qu] = true; - for gi in gate_index.gates_on_qubit_rev(qu) { - if gi >= before_gate { continue; } // already passed - let gi_usize = gi as usize; - if !visited[gi_usize] { - visited[gi_usize] = true; - heap.push(gi); - } - } - } - // Seed from detector — all gates on detector qubits are candidates let total_gates = gates.len() as u32; for &q in &terms[0].pauli.x_qubits { - activate_qubit(q, total_gates, &mut active, &mut visited, &mut heap, gate_index); + activate_qubit( + q, + total_gates, + &mut active, + &mut visited, + &mut heap, + gate_index, + ); } for &q in &terms[0].pauli.z_qubits { - activate_qubit(q, total_gates, &mut active, &mut visited, &mut heap, gate_index); + activate_qubit( + q, + total_gates, + &mut active, + &mut visited, + &mut heap, + gate_index, + ); } let mut last_merge_count = 1usize; @@ -1257,8 +1461,7 @@ pub fn heisenberg_sparse( while let Some(gate_idx) = heap.pop() { let i = gate_idx as usize; let gate = &gates[i]; - let gate_qs: SmallVec<[u16; 4]> = gate.qubits.iter() - .map(|q| q.index() as u16).collect(); + let gate_qs: SmallVec<[u16; 4]> = gate.qubits.iter().map(|q| q.index() as u16).collect(); // Step 1: Apply noise adjoint (skip expansion gates). if !gate_index.is_expansion(i) { @@ -1267,8 +1470,8 @@ pub fn heisenberg_sparse( // Get injections: from noise map or dynamic noise spec let dynamic_injections = if precomputed.is_none() { - let qubits_usize: SmallVec<[usize; 4]> = gate_qs.iter() - .map(|&q| q as usize).collect(); + let qubits_usize: SmallVec<[usize; 4]> = + gate_qs.iter().map(|&q| q as usize).collect(); noise.noise_after_gate(i, gate.gate_type, &qubits_usize) } else { Vec::new() @@ -1283,7 +1486,9 @@ pub fn heisenberg_sparse( match inj.eeg_type { crate::eeg::EegType::H => { let h = inj.rate; - if h.abs() < 1e-20 { continue; } + if h.abs() < 1e-20 { + continue; + } let cos2h = (2.0 * h).cos(); let sin2h = (2.0 * h).sin(); @@ -1302,26 +1507,29 @@ pub fn heisenberg_sparse( sin_branches.clear(); let n = terms.len(); - for idx in 0..n { + for term in terms.iter_mut().take(n) { let anticommutes = if let Some(q) = single_z_qubit { - terms[idx].pauli.has_x(q) + term.pauli.has_x(q) } else { - !terms[idx].pauli.commutes_with(noise_sparse.as_ref().unwrap()) + !term.pauli.commutes_with(noise_sparse.as_ref().unwrap()) }; if anticommutes { - let (sr, si) = - (sin2h * terms[idx].coeff_re, sin2h * terms[idx].coeff_im); + let (sr, si) = (sin2h * term.coeff_re, sin2h * term.coeff_im); let (dp, total_phase) = if let Some(q) = single_z_qubit { - let mut dp = terms[idx].pauli.clone(); + let mut dp = term.pauli.clone(); dp.toggle_z(q); - let has_x = terms[idx].pauli.has_x(q); - let has_z = terms[idx].pauli.has_z(q); - let phase = if has_x { if has_z { 3u8 } else { 1 } } else { 0 }; + let has_x = term.pauli.has_x(q); + let has_z = term.pauli.has_z(q); + let phase = if has_x { + if has_z { 3u8 } else { 1 } + } else { + 0 + }; (dp, (phase + 1) % 4) } else { - let term_bm = terms[idx].pauli.to_bm(); + let term_bm = term.pauli.to_bm(); let (dp_bm, phase_exp) = inj.label.multiply_with_phase(&term_bm); (SparsePauli::from_bm(&dp_bm), (phase_exp + 1) % 4) @@ -1337,21 +1545,37 @@ pub fn heisenberg_sparse( // Check if new term activates new qubits for &q in &dp.x_qubits { - activate_qubit(q, gate_idx, &mut active, &mut visited, &mut heap, gate_index); + activate_qubit( + q, + gate_idx, + &mut active, + &mut visited, + &mut heap, + gate_index, + ); } for &q in &dp.z_qubits { - activate_qubit(q, gate_idx, &mut active, &mut visited, &mut heap, gate_index); + activate_qubit( + q, + gate_idx, + &mut active, + &mut visited, + &mut heap, + gate_index, + ); } sin_branches.push(HeisenbergTerm { - pauli: dp, coeff_re: new_re, coeff_im: new_im, + pauli: dp, + coeff_re: new_re, + coeff_im: new_im, }); - terms[idx].coeff_re *= cos2h; - terms[idx].coeff_im *= cos2h; + term.coeff_re *= cos2h; + term.coeff_im *= cos2h; } } - terms.extend(sin_branches.drain(..)); + terms.append(&mut sin_branches); } crate::eeg::EegType::S => { // S-type: process individually. When using noise map, @@ -1359,7 +1583,9 @@ pub fn heisenberg_sparse( // but unbatchable S injections are placed in h_injections // and must be processed here. let s = inj.rate; - if s.abs() < 1e-20 { continue; } + if s.abs() < 1e-20 { + continue; + } let p = -s; let scale = 1.0 - 2.0 * p; @@ -1434,9 +1660,7 @@ pub fn heisenberg_sparse( // Step 2: Backward Clifford conjugation. match gate.gate_type { GateType::PZ | GateType::QAlloc => { - terms.retain(|t| { - !gate_qs.iter().any(|&qi| t.pauli.has_x(qi)) - }); + terms.retain(|t| !gate_qs.iter().any(|&qi| t.pauli.has_x(qi))); for t in &mut terms { for &qi in &gate_qs { t.pauli.clear_z(qi); @@ -1444,22 +1668,27 @@ pub fn heisenberg_sparse( } } GateType::MZ => { - terms.retain(|t| { - !gate_qs.iter().any(|&qi| t.pauli.has_x(qi)) - }); + terms.retain(|t| !gate_qs.iter().any(|&qi| t.pauli.has_x(qi))); } _ => { for t in &mut terms { - if let Some(sign_neg) = sparse_conjugate(&mut t.pauli, gate) { - if sign_neg { - t.coeff_re = -t.coeff_re; - t.coeff_im = -t.coeff_im; - } + if let Some(sign_neg) = sparse_conjugate(&mut t.pauli, gate) + && sign_neg + { + t.coeff_re = -t.coeff_re; + t.coeff_im = -t.coeff_im; } // Activate any NEW qubits from conjugation (e.g., CX spreads Z) for &q in t.pauli.x_qubits.iter().chain(t.pauli.z_qubits.iter()) { - activate_qubit(q, gate_idx, &mut active, &mut visited, &mut heap, gate_index); + activate_qubit( + q, + gate_idx, + &mut active, + &mut visited, + &mut heap, + gate_index, + ); } } } @@ -1468,9 +1697,7 @@ pub fn heisenberg_sparse( // Prune if prune_threshold > 0.0 { let thresh_sq = prune_threshold * prune_threshold; - terms.retain(|t| { - t.coeff_re * t.coeff_re + t.coeff_im * t.coeff_im > thresh_sq - }); + terms.retain(|t| t.coeff_re * t.coeff_re + t.coeff_im * t.coeff_im > thresh_sq); } // Merge duplicate Pauli terms. @@ -1488,9 +1715,7 @@ pub fn heisenberg_sparse( terms[write].coeff_re += re; terms[write].coeff_im += im; } else { - if terms[write].coeff_re.abs() > 1e-30 - || terms[write].coeff_im.abs() > 1e-30 - { + if terms[write].coeff_re.abs() > 1e-30 || terms[write].coeff_im.abs() > 1e-30 { write += 1; } if write < read { @@ -1529,7 +1754,7 @@ pub fn heisenberg_sparse( } let prob = 0.5 * (1.0 - expectation_re); - prob.max(0.0).min(1.0) + prob.clamp(0.0, 1.0) } /// Convenience: expand an original circuit and compute detection probability. @@ -1572,9 +1797,10 @@ pub fn heisenberg_exact_from_circuit( let expanded = crate::expand::expand_circuit(original_gates); let n = expanded.num_qubits; - if n > 20 { - panic!("Matrix Heisenberg requires 2^n memory; {n} qubits is too large. Use the Pauli-tracking walk for approximate results."); - } + assert!( + n <= 20, + "Matrix Heisenberg requires 2^n memory; {n} qubits is too large. Use the Pauli-tracking walk for approximate results." + ); let dim = 1usize << n; @@ -1586,7 +1812,9 @@ pub fn heisenberg_exact_from_circuit( for &m in detector_meas_indices { if m < expanded.measurement_qubit.len() { let aux = expanded.measurement_qubit[m]; - if (i >> aux) & 1 == 1 { eigenvalue = -eigenvalue; } + if (i >> aux) & 1 == 1 { + eigenvalue = -eigenvalue; + } } } obs_re[i * dim + i] = eigenvalue; @@ -1599,14 +1827,18 @@ pub fn heisenberg_exact_from_circuit( let mut im = obs_im; for idx in (0..expanded.gates.len()).rev() { let g = &expanded.gates[idx]; - let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + let qs: Vec = g.qubits.iter().map(pecos_core::QubitId::index).collect(); // Noise adjoint (skip expansion gates) if !expansion_gates[idx] { let injections = noise.noise_after_gate(idx, g.gate_type, &qs); for inj in &injections { - if inj.eeg_type != crate::eeg::EegType::H { continue; } - if inj.rate.abs() < 1e-20 { continue; } + if inj.eeg_type != crate::eeg::EegType::H { + continue; + } + if inj.rate.abs() < 1e-20 { + continue; + } // RZ(θ) on the noise qubit, where θ = 2*rate let theta = 2.0 * inj.rate; // Find which qubit the noise acts on @@ -1632,10 +1864,8 @@ pub fn heisenberg_exact_from_circuit( GateType::H => { matrix_h_adjoint(&mut obs_re, &mut im, qs[0], n); } - GateType::CX => { - if qs.len() >= 2 { - matrix_cx_adjoint(&mut obs_re, &mut im, qs[0], qs[1], n); - } + GateType::CX if qs.len() >= 2 => { + matrix_cx_adjoint(&mut obs_re, &mut im, qs[0], qs[1], n); } _ => {} } @@ -1644,7 +1874,7 @@ pub fn heisenberg_exact_from_circuit( // ⟨0...0|O_backward|0...0⟩ = obs_re[0] let expectation = obs_re[0]; let prob = 0.5 * (1.0 - expectation); - prob.max(0.0).min(1.0) + prob.clamp(0.0, 1.0) } // --- Matrix helpers for exact Heisenberg --- @@ -1656,7 +1886,9 @@ fn matrix_rz_adjoint(re: &mut [f64], im: &mut [f64], q: usize, theta: f64, n: us for j in 0..dim { let bj = ((j >> q) & 1) as f64; let phase = (bi - bj) * theta; - if phase.abs() < 1e-20 { continue; } + if phase.abs() < 1e-20 { + continue; + } let (cp, sp) = (phase.cos(), phase.sin()); let idx = i * dim + j; let (r, m) = (re[idx], im[idx]); @@ -1674,15 +1906,15 @@ fn matrix_pz_adjoint(re: &mut [f64], im: &mut [f64], q: usize, n: usize) { for j in 0..dim { let jq = (j >> q) & 1; let idx = i * dim + j; - if iq != jq { - re[idx] = 0.0; - im[idx] = 0.0; - } else { + if iq == jq { let i0 = i & !mask; let j0 = j & !mask; let idx0 = i0 * dim + j0; re[idx] = re[idx0]; im[idx] = im[idx0]; + } else { + re[idx] = 0.0; + im[idx] = 0.0; } } } @@ -1722,7 +1954,11 @@ fn matrix_h_adjoint(re: &mut [f64], im: &mut [f64], q: usize, n: usize) { for b in 0..2usize { let ia = if a == 0 { i0 } else { i1 }; let jb = if b == 0 { j0 } else { j1 }; - let sign = if (iq * a + b * jq) % 2 == 0 { 0.5 } else { -0.5 }; + let sign = if (iq * a + b * jq).is_multiple_of(2) { + 0.5 + } else { + -0.5 + }; let idx = ia * dim + jb; sr += sign * re[idx]; si += sign * im[idx]; @@ -1740,9 +1976,7 @@ fn matrix_cx_adjoint(re: &mut [f64], im: &mut [f64], control: usize, target: usi let dim = 1usize << n; let cmask = 1usize << control; let tmask = 1usize << target; - let cx_perm = |i: usize| -> usize { - if (i & cmask) != 0 { i ^ tmask } else { i } - }; + let cx_perm = |i: usize| -> usize { if (i & cmask) != 0 { i ^ tmask } else { i } }; let mut new_re = vec![0.0f64; dim * dim]; let mut new_im = vec![0.0f64; dim * dim]; for i in 0..dim { @@ -1760,16 +1994,22 @@ fn matrix_cx_adjoint(re: &mut [f64], im: &mut [f64], control: usize, target: usi /// Identify expansion gate indices. fn find_expansion_gates(gates: &[Gate]) -> Vec { let mut exp = vec![false; gates.len()]; - if !gates.is_empty() && gates[0].gate_type == GateType::QAlloc { exp[0] = true; } + if !gates.is_empty() && gates[0].gate_type == GateType::QAlloc { + exp[0] = true; + } for i in 1..gates.len() { - if gates[i].gate_type == GateType::QAlloc { exp[i] = true; } - if gates[i].gate_type == GateType::CX && gates[i-1].gate_type == GateType::QAlloc { - let aq = gates[i-1].qubits[0].index(); + if gates[i].gate_type == GateType::QAlloc { + exp[i] = true; + } + if gates[i].gate_type == GateType::CX && gates[i - 1].gate_type == GateType::QAlloc { + let aq = gates[i - 1].qubits[0].index(); if gates[i].qubits.len() >= 2 && gates[i].qubits[1].index() == aq { exp[i] = true; - if i+1 < gates.len() && gates[i+1].gate_type == GateType::PZ - && gates[i+1].qubits[0].index() == gates[i].qubits[0].index() { - exp[i+1] = true; + if i + 1 < gates.len() + && gates[i + 1].gate_type == GateType::PZ + && gates[i + 1].qubits[0].index() == gates[i].qubits[0].index() + { + exp[i + 1] = true; } } } @@ -1780,9 +2020,9 @@ fn find_expansion_gates(gates: &[Gate]) -> Vec { #[cfg(test)] mod tests { use super::*; - use pecos_core::{GateAngles, GateParams, GateQubits, QubitId}; - use crate::noise::UniformNoise; use crate::expand; + use crate::noise::UniformNoise; + use pecos_core::{GateAngles, GateParams, GateQubits, QubitId}; fn gate(gt: GateType, qubits: &[usize]) -> Gate { Gate { @@ -1803,34 +2043,54 @@ mod tests { // X-check ancillas: 4, 5 (H, CX, CX, H, MZ) // Z-check ancilla: 6 (CX, CX, MZ) let gates_orig = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), - gate(GateType::PZ, &[2]), gate(GateType::PZ, &[3]), - gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[3]), + gate(GateType::PZ, &[4]), + gate(GateType::PZ, &[5]), gate(GateType::PZ, &[6]), // Round 1 - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), - gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), - gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), - gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), + gate(GateType::CX, &[5, 3]), + gate(GateType::CX, &[3, 6]), + gate(GateType::CX, &[5, 2]), + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[0, 6]), + gate(GateType::CX, &[4, 0]), + gate(GateType::CX, &[2, 6]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), + gate(GateType::MZ, &[5]), gate(GateType::MZ, &[6]), // Reset - gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[4]), + gate(GateType::PZ, &[5]), gate(GateType::PZ, &[6]), // Round 2 - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), - gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), - gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), - gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), + gate(GateType::CX, &[5, 3]), + gate(GateType::CX, &[3, 6]), + gate(GateType::CX, &[5, 2]), + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[0, 6]), + gate(GateType::CX, &[4, 0]), + gate(GateType::CX, &[2, 6]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), + gate(GateType::MZ, &[5]), gate(GateType::MZ, &[6]), // Final data readout - gate(GateType::MZ, &[0]), gate(GateType::MZ, &[1]), - gate(GateType::MZ, &[2]), gate(GateType::MZ, &[3]), + gate(GateType::MZ, &[0]), + gate(GateType::MZ, &[1]), + gate(GateType::MZ, &[2]), + gate(GateType::MZ, &[3]), ]; let expanded = expand::expand_circuit(&gates_orig); @@ -1858,29 +2118,40 @@ mod tests { det2.z_bits.set_bit(aux_m4); // Run Heisenberg for both detectors - let p1_heis = heisenberg_detection_probability( - &expanded.gates, &det1, &noise, &stab, 1e-10, - ); - let p2_heis = heisenberg_detection_probability( - &expanded.gates, &det2, &noise, &stab, 1e-10, - ); + let p1_heis = + heisenberg_detection_probability(&expanded.gates, &det1, &noise, &stab, 1e-10); + let p2_heis = + heisenberg_detection_probability(&expanded.gates, &det2, &noise, &stab, 1e-10); // For comparison: forward EEG let eeg_result = crate::circuit::analyze_with_noise(&expanded.gates, &noise); let dets = vec![ - crate::dem_mapping::Detector { id: 1, stabilizer: det1 }, - crate::dem_mapping::Detector { id: 2, stabilizer: det2 }, + crate::dem_mapping::Detector { + id: 1, + stabilizer: det1, + }, + crate::dem_mapping::Detector { + id: 2, + stabilizer: det2, + }, ]; let entries = crate::dem_mapping::build_dem_configured( - &eeg_result.generators, &dets, &[], - Some(&stab), &crate::dem_mapping::EegConfig::default(), + &eeg_result.generators, + &dets, + &[], + Some(&stab), + &crate::dem_mapping::EegConfig::default(), ); let mut eeg_d1 = 0.0; let mut eeg_d2 = 0.0; for e in &entries { for &d in &e.event.detectors { - if d == 1 { eeg_d1 += e.probability; } - if d == 2 { eeg_d2 += e.probability; } + if d == 1 { + eeg_d1 += e.probability; + } + if d == 2 { + eeg_d2 += e.probability; + } } } @@ -1901,7 +2172,9 @@ mod tests { // Detector: Z on ancilla (qubit 2) — passes through both MZ(2) gates. // The round-comparison detector fires when the two MZ outcomes differ. let gates_orig = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), // Round 1 gate(GateType::H, &[2]), gate(GateType::CX, &[2, 0]), @@ -1927,9 +2200,7 @@ mod tests { // Detector: Z on ancilla qubit 2 (round-comparison) let det = Bm::z(2); - let p_heis = heisenberg_detection_probability( - &gates_orig, &det, &noise, &stab, 0.0, - ); + let p_heis = heisenberg_detection_probability(&gates_orig, &det, &noise, &stab, 0.0); eprintln!("\nSimple X-check (original circuit), theta={theta}:"); eprintln!(" Heisenberg: {p_heis:.6}"); @@ -1941,11 +2212,14 @@ mod tests { // Parity detector: Z_0 * Z_1 (on original qubits) // Exact answer: p = sin²(theta) let gates_orig = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), gate(GateType::H, &[0]), gate(GateType::CX, &[0, 1]), - gate(GateType::H, &[0]), gate(GateType::H, &[1]), - gate(GateType::MZ, &[0]), gate(GateType::MZ, &[1]), + gate(GateType::H, &[0]), + gate(GateType::H, &[1]), + gate(GateType::MZ, &[0]), + gate(GateType::MZ, &[1]), ]; // Parity detector: Z on both measured qubits (original frame) @@ -1960,18 +2234,21 @@ mod tests { for &theta in &[0.01, 0.05, 0.1, 0.2, 0.5] { let noise = UniformNoise::coherent_only(theta); - let p = heisenberg_detection_probability( - &gates_orig, &det, &noise, &stab, 0.0, - ); + let p = heisenberg_detection_probability(&gates_orig, &det, &noise, &stab, 0.0); let exact = theta.sin().powi(2); let eeg_taylor = theta * theta; // leading-order EEG - eprintln!("theta={theta:.2}: Heisenberg={p:.6}, exact={exact:.6}, Taylor={eeg_taylor:.6}"); + eprintln!( + "theta={theta:.2}: Heisenberg={p:.6}, exact={exact:.6}, Taylor={eeg_taylor:.6}" + ); // Heisenberg should match exact much better than Taylor - assert!((p - exact).abs() < 0.01, - "theta={theta}: Heisenberg {p:.6} vs exact {exact:.6}, diff={:.6}", (p-exact).abs()); + assert!( + (p - exact).abs() < 0.01, + "theta={theta}: Heisenberg {p:.6} vs exact {exact:.6}, diff={:.6}", + (p - exact).abs() + ); } } @@ -1979,19 +2256,24 @@ mod tests { fn test_exact_bell_parity() { // Matrix-based exact Heisenberg should match sin²(θ) perfectly. let gates = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), gate(GateType::H, &[0]), gate(GateType::CX, &[0, 1]), - gate(GateType::H, &[0]), gate(GateType::H, &[1]), - gate(GateType::MZ, &[0]), gate(GateType::MZ, &[1]), + gate(GateType::H, &[0]), + gate(GateType::H, &[1]), + gate(GateType::MZ, &[0]), + gate(GateType::MZ, &[1]), ]; for &theta in &[0.01, 0.05, 0.1, 0.2, 0.5] { let noise = crate::noise::UniformNoise::coherent_only(theta); let p = heisenberg_exact_from_circuit(&gates, &[0, 1], &noise, 2); let exact = theta.sin().powi(2); - assert!((p - exact).abs() < 1e-10, - "theta={theta}: exact_heisenberg {p:.10} vs sin²(θ) {exact:.10}"); + assert!( + (p - exact).abs() < 1e-10, + "theta={theta}: exact_heisenberg {p:.10} vs sin²(θ) {exact:.10}" + ); } } @@ -2000,13 +2282,18 @@ mod tests { // Matrix Heisenberg on the simplest failing case: 2-round, 1 ancilla. // Exact analytical: P = [2 - cos(6θ) - cos(2θ)] / 4. let gates = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), gate(GateType::H, &[2]), - gate(GateType::CX, &[2, 0]), gate(GateType::CX, &[2, 1]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), gate(GateType::H, &[2]), - gate(GateType::MZ, &[2]), gate(GateType::PZ, &[2]), + gate(GateType::MZ, &[2]), + gate(GateType::PZ, &[2]), gate(GateType::H, &[2]), - gate(GateType::CX, &[2, 0]), gate(GateType::CX, &[2, 1]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), gate(GateType::H, &[2]), gate(GateType::MZ, &[2]), ]; @@ -2016,8 +2303,11 @@ mod tests { let p = heisenberg_exact_from_circuit(&gates, &[0, 1], &noise, 3); let exact = (2.0 - (6.0 * theta).cos() - (2.0 * theta).cos()) / 4.0; eprintln!("theta={theta:.2}: exact_heisenberg={p:.10}, analytical={exact:.10}"); - assert!((p - exact).abs() < 1e-8, - "theta={theta}: got {p:.10}, expected {exact:.10}, diff={:.2e}", (p-exact).abs()); + assert!( + (p - exact).abs() < 1e-8, + "theta={theta}: got {p:.10}, expected {exact:.10}, diff={:.2e}", + (p - exact).abs() + ); } } @@ -2029,53 +2319,87 @@ mod tests { // Build a d=2 Z-basis surface code with 2 rounds (same as test above) let gates_orig = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), - gate(GateType::PZ, &[2]), gate(GateType::PZ, &[3]), - gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[3]), + gate(GateType::PZ, &[4]), + gate(GateType::PZ, &[5]), gate(GateType::PZ, &[6]), // Round 1 - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), - gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), - gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), - gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), + gate(GateType::CX, &[5, 3]), + gate(GateType::CX, &[3, 6]), + gate(GateType::CX, &[5, 2]), + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[0, 6]), + gate(GateType::CX, &[4, 0]), + gate(GateType::CX, &[2, 6]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), + gate(GateType::MZ, &[5]), gate(GateType::MZ, &[6]), // Reset + Round 2 - gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[4]), + gate(GateType::PZ, &[5]), gate(GateType::PZ, &[6]), - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), - gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), - gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), - gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), + gate(GateType::CX, &[5, 3]), + gate(GateType::CX, &[3, 6]), + gate(GateType::CX, &[5, 2]), + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[0, 6]), + gate(GateType::CX, &[4, 0]), + gate(GateType::CX, &[2, 6]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), + gate(GateType::MZ, &[5]), gate(GateType::MZ, &[6]), ]; let expanded = crate::expand::expand_circuit(&gates_orig); let gate_index = crate::expand::GateIndex::build(&expanded.gates, expanded.num_qubits); - let init_gates: Vec = (0..7) - .map(|q| gate(GateType::PZ, &[q])) - .collect(); - let stab = crate::stabilizer::StabilizerGroup::from_circuit( - &init_gates, expanded.num_qubits, - ); + let init_gates: Vec = (0..7).map(|q| gate(GateType::PZ, &[q])).collect(); + let stab = + crate::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); // Test both coherent-only and depolarizing noise let noise_configs: Vec<(&str, crate::noise::UniformNoise)> = vec![ - ("coherent_only", crate::noise::UniformNoise::coherent_only(0.05)), - ("depolarizing", crate::noise::UniformNoise { idle_rz: 0.0, p1: 0.001, p2: 0.01, p_meas: 0.001, p_prep: 0.001 }), - ("combined", crate::noise::UniformNoise { idle_rz: 0.05, p1: 0.001, p2: 0.01, p_meas: 0.001, p_prep: 0.001 }), + ( + "coherent_only", + crate::noise::UniformNoise::coherent_only(0.05), + ), + ( + "depolarizing", + crate::noise::UniformNoise { + idle_rz: 0.0, + p1: 0.001, + p2: 0.01, + p_meas: 0.001, + p_prep: 0.001, + }, + ), + ( + "combined", + crate::noise::UniformNoise { + idle_rz: 0.05, + p1: 0.001, + p2: 0.01, + p_meas: 0.001, + p_prep: 0.001, + }, + ), ]; for (label, noise) in &noise_configs { - let noise_map = build_noise_map( - &expanded.gates, noise, &gate_index.expansion_gates, - ); + let noise_map = build_noise_map(&expanded.gates, noise, &gate_index.expansion_gates); // Test all 3 detectors (auxiliary qubits in round 1: meas 0,1,2) for meas_idx in 0..3 { @@ -2084,52 +2408,68 @@ mod tests { // Windowed (old path) let start = Instant::now(); - let p_windowed = heisenberg_windowed( - &expanded.gates, &det, noise, &stab, 1e-12, None, - ); + let p_windowed = + heisenberg_windowed(&expanded.gates, &det, noise, &stab, 1e-12, None); let t_windowed = start.elapsed(); // Sparse without noise map let start = Instant::now(); let p_sparse = heisenberg_sparse( - &expanded.gates, &det, noise, &stab, 1e-12, - &gate_index, None, + &expanded.gates, + &det, + noise, + &stab, + 1e-12, + &gate_index, + None, ); let t_sparse = start.elapsed(); // Sparse with noise map let start = Instant::now(); let p_sparse_nm = heisenberg_sparse( - &expanded.gates, &det, noise, &stab, 1e-12, - &gate_index, Some(&noise_map), + &expanded.gates, + &det, + noise, + &stab, + 1e-12, + &gate_index, + Some(&noise_map), ); let t_sparse_nm = start.elapsed(); // With noise map (old path) let start = Instant::now(); - let p_nm = heisenberg_with_noise_map( - &expanded.gates, &det, &noise_map, &stab, 1e-12, - ); + let p_nm = + heisenberg_with_noise_map(&expanded.gates, &det, &noise_map, &stab, 1e-12); let t_nm = start.elapsed(); // Verify exact match let tol = 1e-12; - assert!((p_windowed - p_sparse).abs() < tol, + assert!( + (p_windowed - p_sparse).abs() < tol, "{label} det{meas_idx}: windowed={p_windowed:.15} vs sparse={p_sparse:.15}, diff={:.2e}", - (p_windowed - p_sparse).abs()); - assert!((p_windowed - p_sparse_nm).abs() < tol, + (p_windowed - p_sparse).abs() + ); + assert!( + (p_windowed - p_sparse_nm).abs() < tol, "{label} det{meas_idx}: windowed={p_windowed:.15} vs sparse+nm={p_sparse_nm:.15}, diff={:.2e}", - (p_windowed - p_sparse_nm).abs()); - assert!((p_windowed - p_nm).abs() < tol, + (p_windowed - p_sparse_nm).abs() + ); + assert!( + (p_windowed - p_nm).abs() < tol, "{label} det{meas_idx}: windowed={p_windowed:.15} vs nm={p_nm:.15}, diff={:.2e}", - (p_windowed - p_nm).abs()); + (p_windowed - p_nm).abs() + ); - eprintln!(" {label} det{meas_idx}: p={p_windowed:.8} \ + eprintln!( + " {label} det{meas_idx}: p={p_windowed:.8} \ windowed={:.1}us sparse={:.1}us sparse+nm={:.1}us nm={:.1}us", t_windowed.as_secs_f64() * 1e6, t_sparse.as_secs_f64() * 1e6, t_sparse_nm.as_secs_f64() * 1e6, - t_nm.as_secs_f64() * 1e6); + t_nm.as_secs_f64() * 1e6 + ); } } } @@ -2144,12 +2484,18 @@ mod tests { use std::time::Instant; let noise = crate::noise::UniformNoise { - idle_rz: 0.05, p1: 0.001, p2: 0.01, p_meas: 0.001, p_prep: 0.001, + idle_rz: 0.05, + p1: 0.001, + p2: 0.01, + p_meas: 0.001, + p_prep: 0.001, }; eprintln!("\n=== Sparse vs Windowed scaling (combined noise) ==="); - eprintln!("{:>4} {:>6} {:>8} {:>8} {:>6} {:>12} {:>12} {:>8}", - "d", "rnds", "gates", "exp_q", "n_det", "windowed_ms", "sparse_ms", "speedup"); + eprintln!( + "{:>4} {:>6} {:>8} {:>8} {:>6} {:>12} {:>12} {:>8}", + "d", "rnds", "gates", "exp_q", "n_det", "windowed_ms", "sparse_ms", "speedup" + ); // Test with increasing circuit sizes. // Repetition codes are 1D — detectors propagate through most gates. @@ -2158,9 +2504,8 @@ mod tests { // --- Repetition codes (1D, low sparsity) --- eprintln!("\n--- Repetition codes (1D) ---"); - let rep_configs: Vec<(usize, usize)> = vec![ - (5, 3), (5, 10), (9, 3), (9, 10), (13, 3), (13, 10), - ]; + let rep_configs: Vec<(usize, usize)> = + vec![(5, 3), (5, 10), (9, 3), (9, 10), (13, 3), (13, 10)]; for &(d, num_rounds) in &rep_configs { let num_data = d; @@ -2202,12 +2547,9 @@ mod tests { let gate_index = crate::expand::GateIndex::build(&expanded.gates, expanded.num_qubits); let noise_map = build_noise_map(&expanded.gates, &noise, &gate_index.expansion_gates); - let init_gates: Vec = (0..num_qubits) - .map(|q| gate(GateType::PZ, &[q])) - .collect(); - let stab = crate::stabilizer::StabilizerGroup::from_circuit( - &init_gates, expanded.num_qubits, - ); + let init_gates: Vec = (0..num_qubits).map(|q| gate(GateType::PZ, &[q])).collect(); + let stab = + crate::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); // Build detectors: round-to-round comparison let num_detectors = num_ancilla * (num_rounds - 1); @@ -2228,7 +2570,11 @@ mod tests { let mut p_windowed = Vec::new(); for det in &detectors { p_windowed.push(heisenberg_with_noise_map( - &expanded.gates, det, &noise_map, &stab, 1e-12, + &expanded.gates, + det, + &noise_map, + &stab, + 1e-12, )); } let t_windowed = start.elapsed(); @@ -2238,24 +2584,34 @@ mod tests { let mut p_sparse = Vec::new(); for det in &detectors { p_sparse.push(heisenberg_sparse( - &expanded.gates, det, &noise, &stab, 1e-12, - &gate_index, Some(&noise_map), + &expanded.gates, + det, + &noise, + &stab, + 1e-12, + &gate_index, + Some(&noise_map), )); } let t_sparse = start.elapsed(); // Verify exact match for (i, (&pw, &ps)) in p_windowed.iter().zip(p_sparse.iter()).enumerate() { - assert!((pw - ps).abs() < 1e-12, + assert!( + (pw - ps).abs() < 1e-12, "d={d} det{i}: windowed={pw:.15} vs sparse={ps:.15}, diff={:.2e}", - (pw - ps).abs()); + (pw - ps).abs() + ); } let speedup = t_windowed.as_secs_f64() / t_sparse.as_secs_f64(); - eprintln!("{d:>4} {num_rounds:>6} {:>8} {:>8} {num_detectors:>6} {:>12.2} {:>12.2} {speedup:>8.1}x", - expanded.gates.len(), expanded.num_qubits, + eprintln!( + "{d:>4} {num_rounds:>6} {:>8} {:>8} {num_detectors:>6} {:>12.2} {:>12.2} {speedup:>8.1}x", + expanded.gates.len(), + expanded.num_qubits, t_windowed.as_secs_f64() * 1000.0, - t_sparse.as_secs_f64() * 1000.0); + t_sparse.as_secs_f64() * 1000.0 + ); } // --- 2D grid codes (high sparsity at large d) --- @@ -2264,8 +2620,10 @@ mod tests { // At d=7: 49 data qubits, 24 Z-stab ancillas, ~500+ expanded gates. // A detector touches ~10 qubits out of ~100+ — high sparsity. eprintln!("\n--- 2D grid codes (surface-code-like) ---"); - eprintln!("{:>4} {:>6} {:>8} {:>8} {:>6} {:>12} {:>12} {:>8}", - "d", "rnds", "gates", "exp_q", "n_det", "windowed_ms", "sparse_ms", "speedup"); + eprintln!( + "{:>4} {:>6} {:>8} {:>8} {:>6} {:>12} {:>12} {:>8}", + "d", "rnds", "gates", "exp_q", "n_det", "windowed_ms", "sparse_ms", "speedup" + ); for &(d, num_rounds) in &[(3, 2), (5, 2), (7, 2), (9, 2), (7, 5), (9, 5)] { // Build a d x d grid with Z-plaquette stabilizers. @@ -2315,12 +2673,9 @@ mod tests { let gate_index = crate::expand::GateIndex::build(&expanded.gates, expanded.num_qubits); let noise_map = build_noise_map(&expanded.gates, &noise, &gate_index.expansion_gates); - let init_gates: Vec = (0..num_qubits) - .map(|q| gate(GateType::PZ, &[q])) - .collect(); - let stab = crate::stabilizer::StabilizerGroup::from_circuit( - &init_gates, expanded.num_qubits, - ); + let init_gates: Vec = (0..num_qubits).map(|q| gate(GateType::PZ, &[q])).collect(); + let stab = + crate::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); // Build detectors: round-to-round comparison of each ancilla let num_detectors = num_ancilla * (num_rounds - 1); @@ -2341,7 +2696,11 @@ mod tests { let mut p_windowed = Vec::new(); for det in &detectors { p_windowed.push(heisenberg_with_noise_map( - &expanded.gates, det, &noise_map, &stab, 1e-12, + &expanded.gates, + det, + &noise_map, + &stab, + 1e-12, )); } let t_windowed = start.elapsed(); @@ -2351,24 +2710,34 @@ mod tests { let mut p_sparse = Vec::new(); for det in &detectors { p_sparse.push(heisenberg_sparse( - &expanded.gates, det, &noise, &stab, 1e-12, - &gate_index, Some(&noise_map), + &expanded.gates, + det, + &noise, + &stab, + 1e-12, + &gate_index, + Some(&noise_map), )); } let t_sparse = start.elapsed(); // Verify exact match for (i, (&pw, &ps)) in p_windowed.iter().zip(p_sparse.iter()).enumerate() { - assert!((pw - ps).abs() < 1e-12, + assert!( + (pw - ps).abs() < 1e-12, "grid d={d} det{i}: windowed={pw:.15} vs sparse={ps:.15}, diff={:.2e}", - (pw - ps).abs()); + (pw - ps).abs() + ); } let speedup = t_windowed.as_secs_f64() / t_sparse.as_secs_f64(); - eprintln!("{d:>4} {num_rounds:>6} {:>8} {:>8} {num_detectors:>6} {:>12.2} {:>12.2} {speedup:>8.1}x", - expanded.gates.len(), expanded.num_qubits, + eprintln!( + "{d:>4} {num_rounds:>6} {:>8} {:>8} {num_detectors:>6} {:>12.2} {:>12.2} {speedup:>8.1}x", + expanded.gates.len(), + expanded.num_qubits, t_windowed.as_secs_f64() * 1000.0, - t_sparse.as_secs_f64() * 1000.0); + t_sparse.as_secs_f64() * 1000.0 + ); } } } diff --git a/exp/pecos-eeg/src/lib.rs b/exp/pecos-eeg/src/lib.rs index 0081580c0..61bb7c921 100644 --- a/exp/pecos-eeg/src/lib.rs +++ b/exp/pecos-eeg/src/lib.rs @@ -10,6 +10,19 @@ // express or implied. See the License for the specific language governing permissions and // limitations under the License. +// The EEG crate is experimental physics/math code. Its core routines use +// numerical casts and dense index-based algebra, and the public API is still +// stabilizing. Keep this list narrow and fix ordinary style lints in code. +#![allow( + clippy::cast_possible_truncation, + clippy::cast_possible_wrap, + clippy::cast_precision_loss, + clippy::cast_sign_loss, + clippy::doc_markdown, + clippy::missing_errors_doc, + clippy::missing_panics_doc +)] + //! Elementary Error Generator (EEG) analysis for coherent noise. //! //! Propagates error generators through Clifford circuits and produces @@ -32,12 +45,12 @@ pub mod correlation_table; pub mod dem_generator; pub mod dem_mapping; pub mod dem_simulator; -pub mod noise_characterization; -pub mod noise_compression; pub mod eeg; pub mod expand; pub mod heisenberg; pub mod noise; +pub mod noise_characterization; +pub mod noise_compression; pub mod propagate; pub mod stabilizer; pub mod strong_sim; diff --git a/exp/pecos-eeg/src/noise.rs b/exp/pecos-eeg/src/noise.rs index 6468db56b..57df69c18 100644 --- a/exp/pecos-eeg/src/noise.rs +++ b/exp/pecos-eeg/src/noise.rs @@ -42,7 +42,12 @@ pub trait NoiseSpec: Send + Sync { /// idle coherent noise is typically injected on both qubits. /// /// Return an empty vec for no noise at this gate. - fn noise_after_gate(&self, gate_index: usize, gate_type: GateType, qubits: &[usize]) -> Vec; + fn noise_after_gate( + &self, + gate_index: usize, + gate_type: GateType, + qubits: &[usize], + ) -> Vec; } /// Uniform noise model: same rates for all gates of each type. @@ -65,12 +70,24 @@ pub struct UniformNoise { impl UniformNoise { #[must_use] pub fn coherent_only(idle_rz: f64) -> Self { - Self { idle_rz, p1: 0.0, p2: 0.0, p_meas: 0.0, p_prep: 0.0 } + Self { + idle_rz, + p1: 0.0, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + } } #[must_use] pub fn depolarizing(p: f64) -> Self { - Self { idle_rz: 0.0, p1: p, p2: p, p_meas: p, p_prep: p } + Self { + idle_rz: 0.0, + p1: p, + p2: p, + p_meas: p, + p_prep: p, + } } #[must_use] @@ -81,15 +98,26 @@ impl UniformNoise { } impl NoiseSpec for UniformNoise { - fn noise_after_gate(&self, _gate_index: usize, gate_type: GateType, qubits: &[usize]) -> Vec { + fn noise_after_gate( + &self, + _gate_index: usize, + gate_type: GateType, + qubits: &[usize], + ) -> Vec { let mut injections = Vec::new(); match gate_type { // Two-qubit gates: idle RZ + depolarizing - GateType::CX | GateType::CZ | GateType::CY | GateType::SWAP - | GateType::SZZ | GateType::SZZdg - | GateType::SXX | GateType::SXXdg - | GateType::SYY | GateType::SYYdg => { + GateType::CX + | GateType::CZ + | GateType::CY + | GateType::SWAP + | GateType::SZZ + | GateType::SZZdg + | GateType::SXX + | GateType::SXXdg + | GateType::SYY + | GateType::SYYdg => { if self.idle_rz.abs() > 0.0 && qubits.len() >= 2 { for &q in &qubits[..2] { injections.push(NoiseInjection { @@ -106,48 +134,45 @@ impl NoiseSpec for UniformNoise { } // Single-qubit Clifford: depolarizing - GateType::H | GateType::SZ | GateType::SZdg - | GateType::SX | GateType::SXdg | GateType::SY | GateType::SYdg - | GateType::X | GateType::Y | GateType::Z => { - if self.p1 > 0.0 && !qubits.is_empty() { - inject_depol_1q(qubits[0], self.p1, &mut injections); - } + GateType::H + | GateType::SZ + | GateType::SZdg + | GateType::SX + | GateType::SXdg + | GateType::SY + | GateType::SYdg + | GateType::X + | GateType::Y + | GateType::Z + if self.p1 > 0.0 && !qubits.is_empty() => + { + inject_depol_1q(qubits[0], self.p1, &mut injections); } // Measurement error - GateType::MZ => { - if self.p_meas > 0.0 { - for &q in qubits { - injections.push(NoiseInjection { - eeg_type: EegType::S, - label: Bm::x(q), - label2: None, - rate: -self.p_meas, - }); - } + GateType::MZ if self.p_meas > 0.0 => { + for &q in qubits { + injections.push(NoiseInjection { + eeg_type: EegType::S, + label: Bm::x(q), + label2: None, + rate: -self.p_meas, + }); } } // Preparation error - GateType::PZ => { - if self.p_prep > 0.0 { - for &q in qubits { - injections.push(NoiseInjection { - eeg_type: EegType::S, - label: Bm::x(q), - label2: None, - rate: -self.p_prep, - }); - } + GateType::PZ if self.p_prep > 0.0 => { + for &q in qubits { + injections.push(NoiseInjection { + eeg_type: EegType::S, + label: Bm::x(q), + label2: None, + rate: -self.p_prep, + }); } } - // Explicit RZ gate - GateType::RZ => { - // Note: RZ angle should be passed via gate.angles, not noise model. - // This case is handled separately in analyze_expanded. - } - _ => {} } @@ -171,8 +196,18 @@ fn inject_depol_2q(qa: usize, qb: usize, prob: f64, out: &mut Vec { + /// Circuit gates. + pub gates: &'a [Gate], + /// Noise model used for exact Heisenberg correlation targets. + pub noise: &'a dyn NoiseSpec, + /// Optional alternate noise model used for DEM mechanism structure. + pub structure_noise: Option<&'a dyn NoiseSpec>, + /// Detector definitions. + pub detectors: &'a [Detector], + /// Observable definitions. + pub observables: &'a [Observable], + /// Initial stabilizer group. + pub initial_stab: &'a StabilizerGroup, + /// Number of circuit qubits. + pub num_qubits: usize, + /// Maximum correlation order to compute. + pub max_order: usize, + /// Drop probabilities below this threshold. + pub prune_threshold: f64, + /// Detector measurement-record definitions. + pub detector_meas_ids: &'a [(usize, Vec, Vec)], + /// Observable measurement-record definitions. + pub observable_meas_ids: &'a [(usize, Vec, Vec)], +} + impl NoiseCharacterization { /// Build from circuit + noise model. /// @@ -77,47 +105,69 @@ impl NoiseCharacterization { /// `structure_noise` (if provided) is used for DEM mechanism extraction — /// useful when passing compressed noise for structure while keeping /// original noise for exact targets. If `None`, uses `noise` for both. - pub fn build( - gates: &[Gate], - noise: &dyn NoiseSpec, - structure_noise: Option<&dyn NoiseSpec>, - detectors: &[Detector], - observables: &[Observable], - initial_stab: &StabilizerGroup, - num_qubits: usize, - max_order: usize, - prune_threshold: f64, - detector_meas_ids: &[(usize, Vec, Vec)], - observable_meas_ids: &[(usize, Vec, Vec)], - ) -> Self { + #[must_use] + pub fn build(input: NoiseCharacterizationInput<'_>) -> Self { + let NoiseCharacterizationInput { + gates, + noise, + structure_noise, + detectors, + observables, + initial_stab, + num_qubits, + max_order, + prune_threshold, + detector_meas_ids, + observable_meas_ids, + } = input; let mechanism_noise = structure_noise.unwrap_or(noise); // Correlation table (always uses exact noise) - let table = compute_correlation_table( - gates, noise, detectors, observables, initial_stab, - num_qubits, max_order, prune_threshold, - ); + let table = compute_correlation_table(CorrelationTableInput { + gates, + noise, + detectors, + observables, + initial_stab, + num_qubits, + max_order, + prune_threshold, + }); // DEM with fitted probabilities (uses mechanism noise for structure) let num_dets = detectors.len(); let mut marginals = vec![0.0_f64; num_dets]; for det in detectors { - if let Some(&p) = table.rates.get(&vec![det.id]) { - if det.id < num_dets { marginals[det.id] = p; } + if let Some(&p) = table.rates.get(&vec![det.id]) + && det.id < num_dets + { + marginals[det.id] = p; } } - let pairwise: Vec<((usize, usize), f64)> = table.rates.iter() + let pairwise: Vec<((usize, usize), f64)> = table + .rates + .iter() .filter(|(k, _)| k.len() == 2) .map(|(k, &v)| ((k[0], k[1]), v)) .collect(); let gate_index = crate::expand::GateIndex::build(gates, num_qubits); let dem_entries = build_coherent_dem_exact( - gates, mechanism_noise, detectors, observables, &gate_index.expansion_gates, - &marginals, Some(&pairwise), + gates, + mechanism_noise, + detectors, + observables, + &gate_index.expansion_gates, + &marginals, + Some(&pairwise), ); let decomposable_entries = crate::coherent_dem::build_coherent_dem_exact_decomposable( - gates, mechanism_noise, detectors, observables, &gate_index.expansion_gates, - &marginals, Some(&pairwise), + gates, + mechanism_noise, + detectors, + observables, + &gate_index.expansion_gates, + &marginals, + Some(&pairwise), ); // Build definitions @@ -142,7 +192,10 @@ impl NoiseCharacterization { for (key, &prob) in &table.rates { if prob > 1e-15 { let labels: Vec = key.iter().map(|&d| format!("D{d}")).collect(); - correlations.push(LabeledCorrelation { labels, probability: prob }); + correlations.push(LabeledCorrelation { + labels, + probability: prob, + }); } } // Add observable correlations @@ -150,16 +203,25 @@ impl NoiseCharacterization { if prob > 1e-15 { let mut labels: Vec = det_ids.iter().map(|&d| format!("D{d}")).collect(); labels.push(format!("L{obs_id}")); - correlations.push(LabeledCorrelation { labels, probability: prob }); + correlations.push(LabeledCorrelation { + labels, + probability: prob, + }); } } // Build labeled mechanisms - let mechanisms: Vec = dem_entries.iter() + let mechanisms: Vec = dem_entries + .iter() .filter(|e| e.probability > 1e-15) .map(|e| LabeledMechanism { detectors: e.event.detectors.iter().map(|&d| format!("D{d}")).collect(), - observables: e.event.observables.iter().map(|&o| format!("L{o}")).collect(), + observables: e + .event + .observables + .iter() + .map(|&o| format!("L{o}")) + .collect(), probability: e.probability, }) .collect(); @@ -177,12 +239,18 @@ impl NoiseCharacterization { /// Output as Stim DEM string. #[must_use] pub fn to_dem_string(&self) -> String { - let entries: Vec = self.mechanisms.iter() + let entries: Vec = self + .mechanisms + .iter() .map(|m| { - let dets: Vec = m.detectors.iter() + let dets: Vec = m + .detectors + .iter() .map(|s| s[1..].parse().unwrap_or(0)) .collect(); - let obs: Vec = m.observables.iter() + let obs: Vec = m + .observables + .iter() .map(|s| s[1..].parse().unwrap_or(0)) .collect(); DemEntry { @@ -211,17 +279,20 @@ impl NoiseCharacterization { pub fn to_json(&self) -> String { let mut j = String::from("{\n"); - j.push_str(&format!(" \"max_order\": {},\n", self.max_order)); - j.push_str(&format!(" \"num_walks\": {},\n", self.num_walks)); + let _ = writeln!(j, " \"max_order\": {},", self.max_order); + let _ = writeln!(j, " \"num_walks\": {},", self.num_walks); // Definitions j.push_str(" \"definitions\": [\n"); for (i, def) in self.definitions.iter().enumerate() { - j.push_str(&format!( + let _ = write!( + j, " {{\"label\": \"{}\", \"meas_ids\": {:?}, \"records\": {:?}}}", def.label, def.meas_ids, def.records - )); - if i + 1 < self.definitions.len() { j.push(','); } + ); + if i + 1 < self.definitions.len() { + j.push(','); + } j.push('\n'); } j.push_str(" ],\n"); @@ -229,11 +300,14 @@ impl NoiseCharacterization { // Correlations j.push_str(" \"correlations\": [\n"); for (i, c) in self.correlations.iter().enumerate() { - j.push_str(&format!( + let _ = write!( + j, " {{\"nodes\": {:?}, \"probability\": {:.10e}}}", c.labels, c.probability - )); - if i + 1 < self.correlations.len() { j.push(','); } + ); + if i + 1 < self.correlations.len() { + j.push(','); + } j.push('\n'); } j.push_str(" ],\n"); @@ -241,13 +315,20 @@ impl NoiseCharacterization { // Mechanisms j.push_str(" \"mechanisms\": [\n"); for (i, m) in self.mechanisms.iter().enumerate() { - let mut nodes: Vec<&str> = m.detectors.iter().map(|s| s.as_str()).collect(); - nodes.extend(m.observables.iter().map(|s| s.as_str())); - j.push_str(&format!( + let mut nodes: Vec<&str> = m + .detectors + .iter() + .map(std::string::String::as_str) + .collect(); + nodes.extend(m.observables.iter().map(std::string::String::as_str)); + let _ = write!( + j, " {{\"nodes\": {:?}, \"probability\": {:.10e}}}", nodes, m.probability - )); - if i + 1 < self.mechanisms.len() { j.push(','); } + ); + if i + 1 < self.mechanisms.len() { + j.push(','); + } j.push('\n'); } j.push_str(" ]\n"); diff --git a/exp/pecos-eeg/src/noise_compression.rs b/exp/pecos-eeg/src/noise_compression.rs index 25cfc970b..3f47a1952 100644 --- a/exp/pecos-eeg/src/noise_compression.rs +++ b/exp/pecos-eeg/src/noise_compression.rs @@ -24,8 +24,8 @@ use crate::Bm; use crate::eeg::EegType; use crate::noise::{NoiseInjection, NoiseSpec}; -use pecos_core::gate_type::GateType; use pecos_core::Gate; +use pecos_core::gate_type::GateType; use smallvec::SmallVec; use std::collections::BTreeMap; @@ -70,9 +70,10 @@ pub fn compress_noise_to_boundaries( expansion_gates: &[bool], ) -> CompressedNoise { let n_gates = gates.len(); - let max_qubit = gates.iter() + let max_qubit = gates + .iter() .flat_map(|g| g.qubits.iter()) - .map(|q| q.index()) + .map(pecos_core::QubitId::index) .max() .unwrap_or(0); @@ -82,7 +83,8 @@ pub fn compress_noise_to_boundaries( if gate_idx < expansion_gates.len() && expansion_gates[gate_idx] { continue; } - let qubits: SmallVec<[usize; 4]> = gate.qubits.iter().map(|q| q.index()).collect(); + let qubits: SmallVec<[usize; 4]> = + gate.qubits.iter().map(pecos_core::QubitId::index).collect(); let injections = noise.noise_after_gate(gate_idx, gate.gate_type, &qubits); for inj in injections { all_noise.push((gate_idx, inj)); @@ -129,8 +131,11 @@ pub fn compress_noise_to_boundaries( match gates[g].gate_type { GateType::MZ | GateType::MeasureFree | GateType::PZ | GateType::QAlloc => { let noise_qubits: Vec = label_qubits(&label, max_qubit); - let boundary_qubits: Vec = gates[g].qubits.iter() - .map(|q| q.index()).collect(); + let boundary_qubits: Vec = gates[g] + .qubits + .iter() + .map(pecos_core::QubitId::index) + .collect(); if noise_qubits.iter().any(|q| boundary_qubits.contains(q)) { // Inject at the gate just before the boundary // (inject_at was set to g-1 by the last non-boundary gate) @@ -158,19 +163,16 @@ pub fn compress_noise_to_boundaries( let boundary_sources: Vec = boundary_groups .into_iter() .filter(|(_, value)| value.abs() > 1e-20) - .map(|((boundary_gate, label, eeg_type), value)| { - BoundaryNoise { - label, - eeg_type, - value, - boundary_gate, - } + .map(|((boundary_gate, label, eeg_type), value)| BoundaryNoise { + label, + eeg_type, + value, + boundary_gate, }) .collect(); - let compressed_count = boundary_sources.len() - + measurement_sources.len() - + preparation_sources.len(); + let compressed_count = + boundary_sources.len() + measurement_sources.len() + preparation_sources.len(); CompressedNoise { boundary_sources, @@ -201,9 +203,14 @@ fn forward_conjugate_label(label: &mut Bm, gate: &Gate) { use crate::heisenberg::{SparsePauli, sparse_conjugate}; match gate.gate_type { - GateType::PZ | GateType::QAlloc | GateType::QFree - | GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked - | GateType::I | GateType::Idle => return, + GateType::PZ + | GateType::QAlloc + | GateType::QFree + | GateType::MZ + | GateType::MeasureFree + | GateType::MeasureLeaked + | GateType::I + | GateType::Idle => return, _ => {} } @@ -272,12 +279,15 @@ impl CompressedNoiseSpec { // Boundary sources → noise at boundary gate for bn in &compressed.boundary_sources { - gate_noise.entry(bn.boundary_gate).or_default().push(NoiseInjection { - eeg_type: bn.eeg_type, - label: bn.label.clone(), - label2: None, - rate: bn.value, - }); + gate_noise + .entry(bn.boundary_gate) + .or_default() + .push(NoiseInjection { + eeg_type: bn.eeg_type, + label: bn.label.clone(), + label2: None, + rate: bn.value, + }); } // Measurement and prep sources stay at original positions @@ -299,7 +309,10 @@ impl NoiseSpec for CompressedNoiseSpec { _gate_type: GateType, _qubits: &[usize], ) -> Vec { - self.gate_noise.get(&gate_index).cloned().unwrap_or_default() + self.gate_noise + .get(&gate_index) + .cloned() + .unwrap_or_default() } } @@ -320,11 +333,21 @@ mod tests { crate::expand::make_gate(GateType::MZ, &[0]), crate::expand::make_gate(GateType::MZ, &[1]), ]; - let noise = UniformNoise { idle_rz: 0.0, p1: 0.001, p2: 0.01, p_meas: 0.01, p_prep: 0.01 }; + let noise = UniformNoise { + idle_rz: 0.0, + p1: 0.001, + p2: 0.01, + p_meas: 0.01, + p_prep: 0.01, + }; let expansion = vec![false; gates.len()]; let result = compress_noise_to_boundaries(&gates, &noise, &expansion); - assert!(result.compressed_count < result.original_count, - "compressed {} should be < original {}", result.compressed_count, result.original_count); + assert!( + result.compressed_count < result.original_count, + "compressed {} should be < original {}", + result.compressed_count, + result.original_count + ); } } diff --git a/exp/pecos-eeg/src/stabilizer.rs b/exp/pecos-eeg/src/stabilizer.rs index 5ac0d292a..867d6c53b 100644 --- a/exp/pecos-eeg/src/stabilizer.rs +++ b/exp/pecos-eeg/src/stabilizer.rs @@ -20,6 +20,7 @@ pub struct StabilizerGroup { impl StabilizerGroup { /// Run the noiseless circuit on SparseStab. + #[must_use] pub fn from_circuit(gates: &[Gate], num_qubits: usize) -> Self { let mut sim = SparseStab::with_seed(num_qubits, 0); @@ -31,37 +32,51 @@ impl StabilizerGroup { match gate.gate_type { GateType::PZ | GateType::QAlloc => { - for &q in &qubits { sim.pz(&[q]); } - } - GateType::H => { sim.h(&qubits); } - GateType::SZ => { sim.sz(&qubits); } - GateType::SZdg => { sim.szdg(&qubits); } - GateType::SX => { sim.sx(&qubits); } - GateType::SXdg => { sim.sxdg(&qubits); } - GateType::SY => { sim.sy(&qubits); } - GateType::SYdg => { sim.sydg(&qubits); } - GateType::X => { sim.x(&qubits); } - GateType::Y => { sim.y(&qubits); } - GateType::Z => { sim.z(&qubits); } - GateType::CX => { - if qubits.len() >= 2 { - sim.cx(&[(qubits[0], qubits[1])]); + for &q in &qubits { + sim.pz(&[q]); } } - GateType::CY => { - if qubits.len() >= 2 { - sim.cy(&[(qubits[0], qubits[1])]); - } + GateType::H => { + sim.h(&qubits); } - GateType::CZ => { - if qubits.len() >= 2 { - sim.cz(&[(qubits[0], qubits[1])]); - } + GateType::SZ => { + sim.sz(&qubits); } - GateType::SWAP => { - if qubits.len() >= 2 { - sim.swap(&[(qubits[0], qubits[1])]); - } + GateType::SZdg => { + sim.szdg(&qubits); + } + GateType::SX => { + sim.sx(&qubits); + } + GateType::SXdg => { + sim.sxdg(&qubits); + } + GateType::SY => { + sim.sy(&qubits); + } + GateType::SYdg => { + sim.sydg(&qubits); + } + GateType::X => { + sim.x(&qubits); + } + GateType::Y => { + sim.y(&qubits); + } + GateType::Z => { + sim.z(&qubits); + } + GateType::CX if qubits.len() >= 2 => { + sim.cx(&[(qubits[0], qubits[1])]); + } + GateType::CY if qubits.len() >= 2 => { + sim.cy(&[(qubits[0], qubits[1])]); + } + GateType::CZ if qubits.len() >= 2 => { + sim.cz(&[(qubits[0], qubits[1])]); + } + GateType::SWAP if qubits.len() >= 2 => { + sim.swap(&[(qubits[0], qubits[1])]); } GateType::MZ => { sim.mz(&qubits); @@ -79,6 +94,7 @@ impl StabilizerGroup { /// - `Some(true)` if P is a +1 stabilizer /// - `Some(false)` if P is a -1 stabilizer (anti-stabilizer) /// - `None` if P is not in the stabilizer group + #[must_use] pub fn is_stabilizer(&self, p: &Bm) -> Option { if p.is_identity() { return Some(true); @@ -97,9 +113,15 @@ impl StabilizerGroup { for q in 0..max_q { let has_x = p.has_x(q); let has_z = p.has_z(q); - if has_x { x_positions.push(q); } - if has_z { z_positions.push(q); } - if has_x && has_z { num_ys += 1; } + if has_x { + x_positions.push(q); + } + if has_z { + z_positions.push(q); + } + if has_x && has_z { + num_ys += 1; + } } let stabs = self.sim.stabs(); @@ -146,13 +168,16 @@ mod tests { #[test] fn test_bell_state() { - let gates = vec![ - gate(GateType::H, &[0]), - gate(GateType::CX, &[0, 1]), - ]; + let gates = vec![gate(GateType::H, &[0]), gate(GateType::CX, &[0, 1])]; let stabs = StabilizerGroup::from_circuit(&gates, 2); - assert_eq!(stabs.is_stabilizer(&Bm::x(0).multiply(&Bm::x(1))), Some(true)); - assert_eq!(stabs.is_stabilizer(&Bm::z(0).multiply(&Bm::z(1))), Some(true)); + assert_eq!( + stabs.is_stabilizer(&Bm::x(0).multiply(&Bm::x(1))), + Some(true) + ); + assert_eq!( + stabs.is_stabilizer(&Bm::z(0).multiply(&Bm::z(1))), + Some(true) + ); } #[test] @@ -171,8 +196,11 @@ mod tests { let stabs = StabilizerGroup::from_circuit(&gates, 5); let x0x1 = Bm::x(0).multiply(&Bm::x(1)); - assert_eq!(stabs.is_stabilizer(&x0x1), Some(true), - "X0*X1 should be stabilizer after syndrome extraction with MZ projection"); + assert_eq!( + stabs.is_stabilizer(&x0x1), + Some(true), + "X0*X1 should be stabilizer after syndrome extraction with MZ projection" + ); } #[test] @@ -184,8 +212,11 @@ mod tests { let stabs = StabilizerGroup::from_circuit(&gates, 1); // Initial state is |0>, X takes it to |1>. // Z|1> = -|1>, so Z is a -1 stabilizer. - assert_eq!(stabs.is_stabilizer(&Bm::z(0)), Some(false), - "Z should be -1 stabilizer for |1> state"); + assert_eq!( + stabs.is_stabilizer(&Bm::z(0)), + Some(false), + "Z should be -1 stabilizer for |1> state" + ); } #[test] @@ -200,10 +231,16 @@ mod tests { ]; let stabs = StabilizerGroup::from_circuit(&gates, 2); // XX should be -1 stabilizer (the minus Bell state) - assert_eq!(stabs.is_stabilizer(&Bm::x(0).multiply(&Bm::x(1))), Some(false), - "XX should be -1 stabilizer for |Phi->"); + assert_eq!( + stabs.is_stabilizer(&Bm::x(0).multiply(&Bm::x(1))), + Some(false), + "XX should be -1 stabilizer for |Phi->" + ); // ZZ should be +1 stabilizer - assert_eq!(stabs.is_stabilizer(&Bm::z(0).multiply(&Bm::z(1))), Some(true), - "ZZ should be +1 stabilizer for |Phi->"); + assert_eq!( + stabs.is_stabilizer(&Bm::z(0).multiply(&Bm::z(1))), + Some(true), + "ZZ should be +1 stabilizer for |Phi->" + ); } } diff --git a/exp/pecos-eeg/src/strong_sim.rs b/exp/pecos-eeg/src/strong_sim.rs index 805518a83..d1242004a 100644 --- a/exp/pecos-eeg/src/strong_sim.rs +++ b/exp/pecos-eeg/src/strong_sim.rs @@ -56,6 +56,7 @@ pub struct OutcomeProbability { /// # Limitations /// Currently computes first-order (S-type) corrections only. H-type /// corrections require second-order computation with phase tracking. +#[must_use] pub fn outcome_probability( generators: &[PropagatedEeg], outcome: &[bool], @@ -72,11 +73,19 @@ pub fn outcome_probability( // For a pure state: ζ = 0 (deterministic), p_x = 0 or 1. // For a projected state: ζ > 0, p_x = 1/2^ζ. let zeta = compute_zeta(n, stabilizers); - let noiseless = if x_in_support { 1.0 / (1u64 << zeta) as f64 } else { 0.0 }; + let noiseless = if x_in_support { + 1.0 / (1u64 << zeta) as f64 + } else { + 0.0 + }; // First-order S-type corrections: α(x, S_P, ψ) = [x⊕a ∈ support] - [x ∈ support] let mut s_correction = 0.0; - let scale = if zeta > 0 { 1.0 / (1u64 << zeta) as f64 } else { 1.0 }; + let scale = if zeta > 0 { + 1.0 / (1u64 << zeta) as f64 + } else { + 1.0 + }; for g in generators { if g.eeg_type != EegType::S { @@ -86,8 +95,8 @@ pub fn outcome_probability( let x_flipped = flip_outcome(outcome, &g.label); let flipped_in_support = is_in_support(&x_flipped, stabilizers); - let alpha = (if flipped_in_support { 1.0 } else { 0.0 }) - - (if x_in_support { 1.0 } else { 0.0 }); + let alpha = + (if flipped_in_support { 1.0 } else { 0.0 }) - (if x_in_support { 1.0 } else { 0.0 }); s_correction += scale * alpha * g.coeff; } @@ -99,11 +108,13 @@ pub fn outcome_probability( // For anticommuting P,P': α(C) = 2 Re(Φ(P,P')) (since {P,P'}=0 → Φ(PP',I) cancels) // // Extract stabilizer phases for Φ computation. - let stab_phases: Vec = stabilizers.iter() + let stab_phases: Vec = stabilizers + .iter() .map(|_| false) // Default: all +1 stabilizers (sign info not available from Bm) .collect(); - let h_gens: Vec<_> = generators.iter() + let h_gens: Vec<_> = generators + .iter() .filter(|g| g.eeg_type == EegType::H) .collect(); @@ -144,8 +155,10 @@ pub fn outcome_probability( let phi_pq = compute_phi(&g.label, q_label, outcome, stabilizers, &stab_phases); let pq = g.label.multiply(q_label); let qp = q_label.multiply(&g.label); - let phi_pq_i = compute_phi(&pq, &Bm::default(), outcome, stabilizers, &stab_phases); - let phi_qp_i = compute_phi(&qp, &Bm::default(), outcome, stabilizers, &stab_phases); + let phi_pq_i = + compute_phi(&pq, &Bm::default(), outcome, stabilizers, &stab_phases); + let phi_qp_i = + compute_phi(&qp, &Bm::default(), outcome, stabilizers, &stab_phases); let alpha = 2.0 * phi_pq.0 - (phi_pq_i.0 + phi_qp_i.0); ca_correction += scale * g.coeff * alpha; } @@ -156,8 +169,10 @@ pub fn outcome_probability( let phi_qp = compute_phi(q_label, &g.label, outcome, stabilizers, &stab_phases); let qp = q_label.multiply(&g.label); let pq = g.label.multiply(q_label); - let phi_qp_i = compute_phi(&qp, &Bm::default(), outcome, stabilizers, &stab_phases); - let phi_pq_i = compute_phi(&pq, &Bm::default(), outcome, stabilizers, &stab_phases); + let phi_qp_i = + compute_phi(&qp, &Bm::default(), outcome, stabilizers, &stab_phases); + let phi_pq_i = + compute_phi(&pq, &Bm::default(), outcome, stabilizers, &stab_phases); let alpha = 2.0 * phi_qp.1 + (phi_qp_i.1 - phi_pq_i.1); ca_correction += scale * g.coeff * alpha; } @@ -166,7 +181,7 @@ pub fn outcome_probability( } } - let total = (noiseless + s_correction + h_correction + ca_correction).max(0.0).min(1.0); + let total = (noiseless + s_correction + h_correction + ca_correction).clamp(0.0, 1.0); OutcomeProbability { noiseless, @@ -208,29 +223,39 @@ fn compute_phi( let n = stabilizers.len(); // Work with full Bm for GF2 ops (only X-part matters) - let mut row_x: Vec = stabilizers.iter() - .map(|s| Bm { x_bits: s.x_bits.clone(), z_bits: Default::default() }) + let mut row_x: Vec = stabilizers + .iter() + .map(|s| Bm { + x_bits: s.x_bits.clone(), + z_bits: smallvec::SmallVec::default(), + }) .collect(); let mut selected = vec![false; n]; - let mut target = Bm { x_bits: target_x.x_bits.clone(), z_bits: Default::default() }; + let mut target = Bm { + x_bits: target_x.x_bits.clone(), + z_bits: smallvec::SmallVec::default(), + }; // GF(2) greedy elimination for bit in 0..outcome.len() { if !target.x_bits.get_bit(bit) { continue; } - let found = row_x.iter().enumerate().find(|(_, r)| r.x_bits.get_bit(bit)); + let found = row_x + .iter() + .enumerate() + .find(|(_, r)| r.x_bits.get_bit(bit)); if let Some((row_idx, _)) = found { // Find the original stabilizer index for this row // (rows may have been XOR-modified but indices track the original) selected[row_idx] = true; let pivot = row_x[row_idx].clone(); target = target.multiply(&pivot); - for r in 0..n { - if r != row_idx && row_x[r].x_bits.get_bit(bit) { + for (r, row) in row_x.iter_mut().enumerate().take(n) { + if r != row_idx && row.x_bits.get_bit(bit) { let p_clone = pivot.clone(); - row_x[r] = row_x[r].multiply(&p_clone); + *row = row.multiply(&p_clone); } } } else { @@ -276,7 +301,7 @@ fn compute_phi( dot += 1; } } - let z_sign: f64 = if dot % 2 == 0 { 1.0 } else { -1.0 }; + let z_sign: f64 = if dot.is_multiple_of(2) { 1.0 } else { -1.0 }; // Total sign from S_0 being a (-1)^{sign} stabilizer let stab_sign: f64 = if s0_sign_minus { -1.0 } else { 1.0 }; @@ -321,7 +346,7 @@ fn is_in_support(outcome: &[bool], stabilizers: &[Bm]) -> bool { } } // Stabilizer eigenvalue should be +1 on support states - if parity % 2 != 0 { + if !parity.is_multiple_of(2) { return false; // eigenvalue = -1, not in support } } @@ -346,7 +371,10 @@ fn compute_zeta(n: usize, stabilizers: &[Bm]) -> usize { let z_stabs: Vec = stabilizers .iter() .filter(|s| s.x_bits.is_zero()) - .map(|s| Bm { x_bits: s.z_bits.clone(), z_bits: Default::default() }) + .map(|s| Bm { + x_bits: s.z_bits.clone(), + z_bits: smallvec::SmallVec::default(), + }) .collect(); let rank = gf2_rank_bitmask(&z_stabs, n); @@ -359,14 +387,21 @@ fn gf2_rank_bitmask(vectors: &[Bm], max_bits: usize) -> usize { let mut rank = 0; for bit in 0..max_bits { - if rank >= rows.len() { break; } - if rows[rank..].iter().all(|r| r.is_identity()) { break; } + if rank >= rows.len() { + break; + } + if rows[rank..] + .iter() + .all(pecos_core::PauliBitmaskGeneric::is_identity) + { + break; + } if let Some(pivot) = rows[rank..].iter().position(|r| r.x_bits.get_bit(bit)) { rows.swap(rank, rank + pivot); let pivot_val = rows[rank].clone(); - for r in 0..rows.len() { - if r != rank && rows[r].x_bits.get_bit(bit) { - rows[r] = rows[r].multiply(&pivot_val); + for (r, row) in rows.iter_mut().enumerate() { + if r != rank && row.x_bits.get_bit(bit) { + *row = row.multiply(&pivot_val); } } rank += 1; @@ -380,15 +415,19 @@ fn gf2_rank_bitmask(vectors: &[Bm], max_bits: usize) -> usize { mod tests { use super::*; - fn xx() -> Bm { Bm::x(0).multiply(&Bm::x(1)) } - fn zz() -> Bm { Bm::z(0).multiply(&Bm::z(1)) } + fn xx() -> Bm { + Bm::x(0).multiply(&Bm::x(1)) + } + fn zz() -> Bm { + Bm::z(0).multiply(&Bm::z(1)) + } #[test] fn test_single_qubit_z_basis() { // |0⟩ state: stabilizer = +Z. Outcome 0 is deterministic. let stabs = vec![Bm::z(0)]; let outcome_0 = vec![false]; // |0⟩ - let outcome_1 = vec![true]; // |1⟩ + let outcome_1 = vec![true]; // |1⟩ assert!(is_in_support(&outcome_0, &stabs)); assert!(!is_in_support(&outcome_1, &stabs)); @@ -496,9 +535,9 @@ mod tests { // Support: {00, 11} (Z-type stabilizer ZZ constrains parity) assert!(is_in_support(&[false, false], &stabs)); // 00: ZZ eigenvalue = (-1)^0 = +1 - assert!(is_in_support(&[true, true], &stabs)); // 11: ZZ eigenvalue = (-1)^2 = +1 - assert!(!is_in_support(&[false, true], &stabs)); // 01: ZZ eigenvalue = (-1)^1 = -1 - assert!(!is_in_support(&[true, false], &stabs)); // 10: ZZ eigenvalue = (-1)^1 = -1 + assert!(is_in_support(&[true, true], &stabs)); // 11: ZZ eigenvalue = (-1)^2 = +1 + assert!(!is_in_support(&[false, true], &stabs)); // 01: ZZ eigenvalue = (-1)^1 = -1 + assert!(!is_in_support(&[true, false], &stabs)); // 10: ZZ eigenvalue = (-1)^1 = -1 } #[test] @@ -521,41 +560,30 @@ mod tests { let phases = vec![false]; // +1 stabilizer // Φ(I,I) for outcome 0 (in support): should be 1 - let phi = compute_phi( - &Bm::default(), &Bm::default(), - &[false], &stabs, &phases, - ); + let phi = compute_phi(&Bm::default(), &Bm::default(), &[false], &stabs, &phases); assert!((phi.0 - 1.0).abs() < 1e-10); assert!(phi.1.abs() < 1e-10); // Φ(I,I) for outcome 1 (not in support): should be 0 - let phi = compute_phi( - &Bm::default(), &Bm::default(), - &[true], &stabs, &phases, - ); + let phi = compute_phi(&Bm::default(), &Bm::default(), &[true], &stabs, &phases); assert!(phi.0.abs() < 1e-10); // Φ(X,X) for outcome 0: ⟨0|X|0⟩² = 0 (X flips to |1⟩ which is not in support... // wait, x⊕a_X = 1, is |1⟩ in support? No. So Φ = 0. - let phi = compute_phi( - &Bm::x(0), &Bm::x(0), - &[false], &stabs, &phases, - ); + let phi = compute_phi(&Bm::x(0), &Bm::x(0), &[false], &stabs, &phases); assert!(phi.0.abs() < 1e-10); // Φ(X,X) for outcome 1: ⟨1|X|0⟩·⟨0|X|1⟩ = ⟨1|1⟩·⟨0|0⟩ = 1 // x⊕a_X = 0, which IS in support. So Φ should be 1. - let phi = compute_phi( - &Bm::x(0), &Bm::x(0), - &[true], &stabs, &phases, + let phi = compute_phi(&Bm::x(0), &Bm::x(0), &[true], &stabs, &phases); + assert!( + (phi.0 - 1.0).abs() < 1e-10, + "Phi(X,X) at |1> for |0> state: got {:?}", + phi ); - assert!((phi.0 - 1.0).abs() < 1e-10, "Phi(X,X) at |1> for |0> state: got {:?}", phi); // Φ(Z,I) for outcome 0: ⟨0|Z|0⟩·⟨0|0⟩ = 1·1 = 1 - let phi = compute_phi( - &Bm::z(0), &Bm::default(), - &[false], &stabs, &phases, - ); + let phi = compute_phi(&Bm::z(0), &Bm::default(), &[false], &stabs, &phases); assert!((phi.0 - 1.0).abs() < 1e-10); } @@ -567,30 +595,30 @@ mod tests { // Φ(I,I) for outcome 00 (in support): 2^ζ · |⟨00|Φ+⟩|² = 2 · 1/2 = 1 let phi = compute_phi( - &Bm::default(), &Bm::default(), - &[false, false], &stabs, &phases, + &Bm::default(), + &Bm::default(), + &[false, false], + &stabs, + &phases, ); assert!((phi.0 - 1.0).abs() < 1e-10, "Phi(I,I) at 00: {:?}", phi); // Φ(I,I) for outcome 01 (not in support): 0 let phi = compute_phi( - &Bm::default(), &Bm::default(), - &[false, true], &stabs, &phases, + &Bm::default(), + &Bm::default(), + &[false, true], + &stabs, + &phases, ); assert!(phi.0.abs() < 1e-10); // Φ(Z0,I) for outcome 00 - let phi = compute_phi( - &Bm::z(0), &Bm::default(), - &[false, false], &stabs, &phases, - ); + let phi = compute_phi(&Bm::z(0), &Bm::default(), &[false, false], &stabs, &phases); assert!((phi.0 - 1.0).abs() < 1e-10, "Phi(Z0,I) at 00: {:?}", phi); // Φ(Z0,I) for outcome 11 - let phi = compute_phi( - &Bm::z(0), &Bm::default(), - &[true, true], &stabs, &phases, - ); + let phi = compute_phi(&Bm::z(0), &Bm::default(), &[true, true], &stabs, &phases); assert!((phi.0 + 1.0).abs() < 1e-10, "Phi(Z0,I) at 11: {:?}", phi); } @@ -619,7 +647,10 @@ mod tests { assert!(p10.noiseless.abs() < 1e-10); // S_{Z₀} on |Φ+⟩: Z₀ maps |Φ+⟩ to |Φ-⟩. No Z-basis effect. - assert!(p00.s_correction.abs() < 1e-10, "Z error on Bell state: no Z-basis effect"); + assert!( + p00.s_correction.abs() < 1e-10, + "Z error on Bell state: no Z-basis effect" + ); assert!(p11.s_correction.abs() < 1e-10); } } diff --git a/exp/pecos-eeg/tests/beta_investigation.rs b/exp/pecos-eeg/tests/beta_investigation.rs index 7dabba98c..cce7af4cd 100644 --- a/exp/pecos-eeg/tests/beta_investigation.rs +++ b/exp/pecos-eeg/tests/beta_investigation.rs @@ -7,7 +7,7 @@ use pecos_core::gate_type::GateType; use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; use pecos_eeg::Bm; -use pecos_eeg::circuit::{analyze_expanded, NoiseModel, PropagatedEeg}; +use pecos_eeg::circuit::{NoiseModel, PropagatedEeg, analyze_expanded}; use pecos_eeg::eeg::EegType; use pecos_eeg::expand; use pecos_eeg::stabilizer::StabilizerGroup; @@ -18,7 +18,7 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), angles: GateAngles::new(), params: GateParams::new(), - meas_ids: pecos_core::GateMeasIds::new(), + meas_ids: pecos_core::GateMeasIds::new(), } } @@ -53,12 +53,18 @@ fn test_zbasis_generator_labels() { let gates = build_minimal_zbasis(); let expanded = expand::expand_circuit(&gates); - eprintln!("Expanded circuit: {} qubits ({} original + {} aux)", - expanded.num_qubits, expanded.num_original_qubits, - expanded.num_qubits - expanded.num_original_qubits); + eprintln!( + "Expanded circuit: {} qubits ({} original + {} aux)", + expanded.num_qubits, + expanded.num_original_qubits, + expanded.num_qubits - expanded.num_original_qubits + ); eprintln!("Measurement mapping:"); - for (i, (&aux, &orig)) in expanded.measurement_qubit.iter() - .zip(expanded.original_measured_qubit.iter()).enumerate() + for (i, (&aux, &orig)) in expanded + .measurement_qubit + .iter() + .zip(expanded.original_measured_qubit.iter()) + .enumerate() { eprintln!(" meas {i}: aux={aux} orig={orig}"); } @@ -66,15 +72,19 @@ fn test_zbasis_generator_labels() { let noise = NoiseModel::coherent_only(0.001); let result = analyze_expanded(&expanded.gates, &noise); - let h_gens: Vec<&PropagatedEeg> = result.generators.iter() + let h_gens: Vec<&PropagatedEeg> = result + .generators + .iter() .filter(|g| g.eeg_type == EegType::H) .collect(); eprintln!("\nH generators ({}):", h_gens.len()); for (i, g) in h_gens.iter().enumerate() { let orig = expanded.map_to_original_frame(&g.label); - eprintln!(" [{i}] expanded={:?} coeff={:.6} original_frame={:?}", - g.label, g.coeff, orig); + eprintln!( + " [{i}] expanded={:?} coeff={:.6} original_frame={:?}", + g.label, g.coeff, orig + ); } // Check products of all pairs @@ -82,7 +92,7 @@ fn test_zbasis_generator_labels() { let stab_group = StabilizerGroup::from_circuit(&gates, expanded.num_original_qubits); for j in 0..h_gens.len() { - for k in (j+1)..h_gens.len() { + for k in (j + 1)..h_gens.len() { let qj = &h_gens[j].label; let qk = &h_gens[k].label; if !qj.commutes_with(qk) { @@ -93,8 +103,10 @@ fn test_zbasis_generator_labels() { let is_stab = stab_group.is_stabilizer(&orig_product); if is_stab.is_some() || !orig_product.is_identity() { - eprintln!(" [{j},{k}] commute=true product_orig={:?} is_stab={:?}", - orig_product, is_stab); + eprintln!( + " [{j},{k}] commute=true product_orig={:?} is_stab={:?}", + orig_product, is_stab + ); } } } @@ -104,7 +116,10 @@ fn test_zbasis_generator_labels() { fn test_zbasis_stabilizer_group() { let gates = build_minimal_zbasis(); // Exclude final MZ readout — keep syndrome MZ - let last_non_mz = gates.iter().rposition(|g| g.gate_type != GateType::MZ).unwrap(); + let last_non_mz = gates + .iter() + .rposition(|g| g.gate_type != GateType::MZ) + .unwrap(); let gates_pre = &gates[..=last_non_mz]; let stab_group = StabilizerGroup::from_circuit(gates_pre, 3); @@ -116,10 +131,23 @@ fn test_zbasis_stabilizer_group() { for g in gates_pre { let qs: Vec = g.qubits.iter().copied().collect(); match g.gate_type { - GateType::PZ => { for &q in &qs { sim.pz(&[q]); } } - GateType::H => { sim.h(&qs); } - GateType::CX => { if qs.len() >= 2 { sim.cx(&[(qs[0], qs[1])]); } } - GateType::MZ => { let _r = sim.mz(&qs); eprintln!(" MZ({:?})", qs); } + GateType::PZ => { + for &q in &qs { + sim.pz(&[q]); + } + } + GateType::H => { + sim.h(&qs); + } + GateType::CX => { + if qs.len() >= 2 { + sim.cx(&[(qs[0], qs[1])]); + } + } + GateType::MZ => { + let _r = sim.mz(&qs); + eprintln!(" MZ({:?})", qs); + } _ => {} } } diff --git a/exp/pecos-eeg/tests/generator_trace.rs b/exp/pecos-eeg/tests/generator_trace.rs index 25a016aa4..e40cac1cd 100644 --- a/exp/pecos-eeg/tests/generator_trace.rs +++ b/exp/pecos-eeg/tests/generator_trace.rs @@ -9,7 +9,7 @@ use pecos_core::gate_type::GateType; use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; use pecos_eeg::Bm; -use pecos_eeg::circuit::{analyze_expanded, NoiseModel}; +use pecos_eeg::circuit::{NoiseModel, analyze_expanded}; use pecos_eeg::dem_mapping::*; use pecos_eeg::eeg::EegType; use pecos_eeg::expand; @@ -21,7 +21,7 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), angles: GateAngles::new(), params: GateParams::new(), - meas_ids: pecos_core::GateMeasIds::new(), + meas_ids: pecos_core::GateMeasIds::new(), } } @@ -30,34 +30,54 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { fn build_d2_zbasis() -> Vec { vec![ // Init - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), - gate(GateType::PZ, &[2]), gate(GateType::PZ, &[3]), - gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[3]), + gate(GateType::PZ, &[4]), + gate(GateType::PZ, &[5]), gate(GateType::PZ, &[6]), // Round 1 - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), // tick 3 - gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), // tick 4 - gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), // tick 5 - gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), // tick 6 - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), + gate(GateType::CX, &[5, 3]), // tick 3 + gate(GateType::CX, &[3, 6]), + gate(GateType::CX, &[5, 2]), // tick 4 + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[0, 6]), // tick 5 + gate(GateType::CX, &[4, 0]), + gate(GateType::CX, &[2, 6]), // tick 6 + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), + gate(GateType::MZ, &[5]), gate(GateType::MZ, &[6]), // Reset - gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[4]), + gate(GateType::PZ, &[5]), gate(GateType::PZ, &[6]), // Round 2 - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), // tick 11 - gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), // tick 12 - gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), // tick 13 - gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), // tick 14 - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), + gate(GateType::CX, &[5, 3]), // tick 11 + gate(GateType::CX, &[3, 6]), + gate(GateType::CX, &[5, 2]), // tick 12 + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[0, 6]), // tick 13 + gate(GateType::CX, &[4, 0]), + gate(GateType::CX, &[2, 6]), // tick 14 + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), + gate(GateType::MZ, &[5]), gate(GateType::MZ, &[6]), // Final data readout - gate(GateType::MZ, &[0]), gate(GateType::MZ, &[1]), - gate(GateType::MZ, &[2]), gate(GateType::MZ, &[3]), + gate(GateType::MZ, &[0]), + gate(GateType::MZ, &[1]), + gate(GateType::MZ, &[2]), + gate(GateType::MZ, &[3]), ] } @@ -68,14 +88,20 @@ fn trace_d2_zbasis_generators() { let noise = NoiseModel::coherent_only(0.01); let result = analyze_expanded(&expanded.gates, &noise); - eprintln!("Expanded: {} qubits ({} orig + {} aux), {} measurements", - expanded.num_qubits, expanded.num_original_qubits, + eprintln!( + "Expanded: {} qubits ({} orig + {} aux), {} measurements", + expanded.num_qubits, + expanded.num_original_qubits, expanded.num_qubits - expanded.num_original_qubits, - expanded.measurement_qubit.len()); + expanded.measurement_qubit.len() + ); eprintln!("\nMeasurement mapping:"); - for (i, (&aux, &orig)) in expanded.measurement_qubit.iter() - .zip(expanded.original_measured_qubit.iter()).enumerate() + for (i, (&aux, &orig)) in expanded + .measurement_qubit + .iter() + .zip(expanded.original_measured_qubit.iter()) + .enumerate() { eprintln!(" meas[{i}]: aux=q{aux}, orig=q{orig}"); } @@ -94,12 +120,20 @@ fn trace_d2_zbasis_generators() { eprintln!("D2 stabilizer: Z on aux q{aux_m1} and q{aux_m4} (ancilla 5 rounds 1&2)"); let _dets = vec![ - Detector { id: 1, stabilizer: d1_stab.clone() }, - Detector { id: 2, stabilizer: d2_stab.clone() }, + Detector { + id: 1, + stabilizer: d1_stab.clone(), + }, + Detector { + id: 2, + stabilizer: d2_stab.clone(), + }, ]; // Classify each H generator - let h_gens: Vec<_> = result.generators.iter() + let h_gens: Vec<_> = result + .generators + .iter() .filter(|g| g.eeg_type == EegType::H) .collect(); @@ -114,11 +148,17 @@ fn trace_d2_zbasis_generators() { if flips_d1 || flips_d2 { let orig = expanded.map_to_original_frame(&g.label); - eprintln!(" {:?} coeff={:.6} -> orig={:?} flips: D1={} D2={}", - g.label, g.coeff, orig, flips_d1, flips_d2); + eprintln!( + " {:?} coeff={:.6} -> orig={:?} flips: D1={} D2={}", + g.label, g.coeff, orig, flips_d1, flips_d2 + ); - if flips_d1 { d1_gens.push((g.label.clone(), g.coeff)); } - if flips_d2 { d2_gens.push((g.label.clone(), g.coeff)); } + if flips_d1 { + d1_gens.push((g.label.clone(), g.coeff)); + } + if flips_d2 { + d2_gens.push((g.label.clone(), g.coeff)); + } } } @@ -136,18 +176,29 @@ fn trace_d2_zbasis_generators() { use std::collections::BTreeMap; let mut d1_bch: BTreeMap = BTreeMap::new(); let mut d2_bch: BTreeMap = BTreeMap::new(); - for (l, c) in &d1_gens { *d1_bch.entry(l.clone()).or_default() += c; } - for (l, c) in &d2_gens { *d2_bch.entry(l.clone()).or_default() += c; } + for (l, c) in &d1_gens { + *d1_bch.entry(l.clone()).or_default() += c; + } + for (l, c) in &d2_gens { + *d2_bch.entry(l.clone()).or_default() += c; + } eprintln!("\nD1 after BCH: {} distinct labels", d1_bch.len()); - for (l, c) in &d1_bch { eprintln!(" {:?} rate={:.6}", l, c); } + for (l, c) in &d1_bch { + eprintln!(" {:?} rate={:.6}", l, c); + } eprintln!("\nD2 after BCH: {} distinct labels", d2_bch.len()); - for (l, c) in &d2_bch { eprintln!(" {:?} rate={:.6}", l, c); } + for (l, c) in &d2_bch { + eprintln!(" {:?} rate={:.6}", l, c); + } // Verify asymmetry in generator counts - assert_ne!(d1_bch.len(), d2_bch.len(), - "D1 and D2 should have different numbers of BCH-combined generators"); + assert_ne!( + d1_bch.len(), + d2_bch.len(), + "D1 and D2 should have different numbers of BCH-combined generators" + ); // Compute probabilities manually to trace the beta function let gates_pre = crate::exclude_final_readout(&gates); @@ -178,12 +229,26 @@ fn trace_d2_zbasis_generators() { let mut sim = SparseStab::with_seed(7, 0); for g in &gates_pre { let qs: Vec = g.qubits.iter().copied().collect(); - if qs.is_empty() { continue; } + if qs.is_empty() { + continue; + } match g.gate_type { - GateType::PZ => { for &q in &qs { sim.pz(&[q]); } } - GateType::H => { sim.h(&qs); } - GateType::CX => { if qs.len() >= 2 { sim.cx(&[(qs[0], qs[1])]); } } - GateType::MZ => { let _ = sim.mz(&qs); } + GateType::PZ => { + for &q in &qs { + sim.pz(&[q]); + } + } + GateType::H => { + sim.h(&qs); + } + GateType::CX => { + if qs.len() >= 2 { + sim.cx(&[(qs[0], qs[1])]); + } + } + GateType::MZ => { + let _ = sim.mz(&qs); + } _ => {} } } @@ -209,11 +274,23 @@ fn trace_d2_zbasis_generators() { let mut sim2 = SparseStab::with_seed(7, 0); for g in &gates_pre { let qs: Vec = g.qubits.iter().copied().collect(); - if qs.is_empty() { continue; } + if qs.is_empty() { + continue; + } match g.gate_type { - GateType::PZ => { for &q in &qs { sim2.pz(&[q]); } } - GateType::H => { sim2.h(&qs); } - GateType::CX => { if qs.len() >= 2 { sim2.cx(&[(qs[0], qs[1])]); } } + GateType::PZ => { + for &q in &qs { + sim2.pz(&[q]); + } + } + GateType::H => { + sim2.h(&qs); + } + GateType::CX => { + if qs.len() >= 2 { + sim2.cx(&[(qs[0], qs[1])]); + } + } GateType::MZ => { /* skip */ } _ => {} } @@ -238,13 +315,22 @@ fn trace_d2_zbasis_generators() { } // Check: how many qubits in the stabilizer group? And test Z0Z1Z2Z3 - let z_all = Bm::z(0).multiply(&Bm::z(1)).multiply(&Bm::z(2)).multiply(&Bm::z(3)); + let z_all = Bm::z(0) + .multiply(&Bm::z(1)) + .multiply(&Bm::z(2)) + .multiply(&Bm::z(3)); eprintln!("Z0Z1Z2Z3: {:?}", stab_group.is_stabilizer(&z_all)); let _z01 = Bm::z(0).multiply(&Bm::z(1)); let z23 = Bm::z(2).multiply(&Bm::z(3)); eprintln!("Z2Z3: {:?}", stab_group.is_stabilizer(&z23)); - eprintln!("Z0Z1Z2: {:?}", stab_group.is_stabilizer(&Bm::z(0).multiply(&Bm::z(1)).multiply(&Bm::z(2)))); - eprintln!("Z1Z2: {:?}", stab_group.is_stabilizer(&Bm::z(1).multiply(&Bm::z(2)))); + eprintln!( + "Z0Z1Z2: {:?}", + stab_group.is_stabilizer(&Bm::z(0).multiply(&Bm::z(1)).multiply(&Bm::z(2))) + ); + eprintln!( + "Z1Z2: {:?}", + stab_group.is_stabilizer(&Bm::z(1).multiply(&Bm::z(2))) + ); for (det_name, bch) in [("D1", &d1_bch), ("D2", &d2_bch)] { let labels: Vec = bch.keys().cloned().collect(); @@ -260,7 +346,7 @@ fn trace_d2_zbasis_generators() { for j in 0..n { diag += coeffs[j] * coeffs[j]; - for k in (j+1)..n { + for k in (j + 1)..n { if !labels[j].commutes_with(&labels[k]) { offdiag_anticommute += 1; continue; @@ -284,8 +370,10 @@ fn trace_d2_zbasis_generators() { } None => { offdiag_zero += 1; - eprintln!(" beta=0: {:?} * {:?} = {:?} (orig: {:?})", - labels[j], labels[k], product, orig_product); + eprintln!( + " beta=0: {:?} * {:?} = {:?} (orig: {:?})", + labels[j], labels[k], product, orig_product + ); } } } @@ -294,7 +382,9 @@ fn trace_d2_zbasis_generators() { let total = diag + offdiag; eprintln!("\n{det_name} probability breakdown:"); eprintln!(" Diagonal: {diag:.8}"); - eprintln!(" Off-diagonal: {offdiag:.8} (+{offdiag_plus} pairs, -{offdiag_minus} pairs, 0:{offdiag_zero} pairs, anticommute:{offdiag_anticommute})"); + eprintln!( + " Off-diagonal: {offdiag:.8} (+{offdiag_plus} pairs, -{offdiag_minus} pairs, 0:{offdiag_zero} pairs, anticommute:{offdiag_anticommute})" + ); eprintln!(" Total: {total:.8}"); } } @@ -305,16 +395,27 @@ fn exclude_final_readout(gates: &[Gate]) -> Vec { let mut past_init = false; for g in gates { if past_init && (g.gate_type == GateType::PZ || g.gate_type == GateType::QAlloc) { - for q in &g.qubits { ancilla_qubits.insert(q.index()); } + for q in &g.qubits { + ancilla_qubits.insert(q.index()); + } + } + if g.gate_type != GateType::PZ && g.gate_type != GateType::QAlloc { + past_init = true; } - if g.gate_type != GateType::PZ && g.gate_type != GateType::QAlloc { past_init = true; } } let mut end = gates.len(); for g in gates.iter().rev() { - if g.gate_type != GateType::MZ { break; } - if g.qubits.iter().all(|q| !ancilla_qubits.contains(&q.index())) { + if g.gate_type != GateType::MZ { + break; + } + if g.qubits + .iter() + .all(|q| !ancilla_qubits.contains(&q.index())) + { end -= 1; - } else { break; } + } else { + break; + } } gates[..end].to_vec() } diff --git a/exp/pecos-eeg/tests/stabilizer_audit.rs b/exp/pecos-eeg/tests/stabilizer_audit.rs index 061eb1cf5..ee44464d4 100644 --- a/exp/pecos-eeg/tests/stabilizer_audit.rs +++ b/exp/pecos-eeg/tests/stabilizer_audit.rs @@ -18,7 +18,7 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), angles: GateAngles::new(), params: GateParams::new(), - meas_ids: pecos_core::GateMeasIds::new(), + meas_ids: pecos_core::GateMeasIds::new(), } } @@ -43,18 +43,46 @@ fn audit_stabilizer_group(label: &str, gates: &[Gate], num_qubits: usize) { let mut sim = SparseStab::with_seed(num_qubits, 0); for g in gates { let qs: Vec = g.qubits.iter().copied().collect(); - if qs.is_empty() { continue; } + if qs.is_empty() { + continue; + } match g.gate_type { - GateType::PZ | GateType::QAlloc => { for &q in &qs { sim.pz(&[q]); } } - GateType::H => { sim.h(&qs); } - GateType::SZ => { sim.sz(&qs); } - GateType::SZdg => { sim.szdg(&qs); } - GateType::X => { sim.x(&qs); } - GateType::Y => { sim.y(&qs); } - GateType::Z => { sim.z(&qs); } - GateType::CX => { if qs.len() >= 2 { sim.cx(&[(qs[0], qs[1])]); } } - GateType::CZ => { if qs.len() >= 2 { sim.cz(&[(qs[0], qs[1])]); } } - GateType::MZ => { sim.mz(&qs); } + GateType::PZ | GateType::QAlloc => { + for &q in &qs { + sim.pz(&[q]); + } + } + GateType::H => { + sim.h(&qs); + } + GateType::SZ => { + sim.sz(&qs); + } + GateType::SZdg => { + sim.szdg(&qs); + } + GateType::X => { + sim.x(&qs); + } + GateType::Y => { + sim.y(&qs); + } + GateType::Z => { + sim.z(&qs); + } + GateType::CX => { + if qs.len() >= 2 { + sim.cx(&[(qs[0], qs[1])]); + } + } + GateType::CZ => { + if qs.len() >= 2 { + sim.cz(&[(qs[0], qs[1])]); + } + } + GateType::MZ => { + sim.mz(&qs); + } _ => {} } } @@ -95,9 +123,11 @@ fn audit_stabilizer_group(label: &str, gates: &[Gate], num_qubits: usize) { } } - assert!(failures.is_empty(), + assert!( + failures.is_empty(), "{label}: {}/{max_subsets} stabilizer products not found by is_stabilizer", - failures.len()); + failures.len() + ); } #[test] @@ -109,65 +139,92 @@ fn audit_simple_states() { audit_stabilizer_group("|+>", &[gate(GateType::H, &[0])], 1); // Bell state - audit_stabilizer_group("|Phi+>", &[ - gate(GateType::H, &[0]), - gate(GateType::CX, &[0, 1]), - ], 2); + audit_stabilizer_group( + "|Phi+>", + &[gate(GateType::H, &[0]), gate(GateType::CX, &[0, 1])], + 2, + ); } #[test] fn audit_syndrome_extraction() { // Simple 2-qubit Z-check with ancilla: PZ(0,1,2), CX(0,2), CX(1,2), MZ(2) - audit_stabilizer_group("Z-check 2q", &[ - gate(GateType::PZ, &[0]), - gate(GateType::PZ, &[1]), - gate(GateType::PZ, &[2]), - gate(GateType::CX, &[0, 2]), - gate(GateType::CX, &[1, 2]), - gate(GateType::MZ, &[2]), - ], 3); + audit_stabilizer_group( + "Z-check 2q", + &[ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::CX, &[0, 2]), + gate(GateType::CX, &[1, 2]), + gate(GateType::MZ, &[2]), + ], + 3, + ); // X-check: H(2), CX(2,0), CX(2,1), H(2), MZ(2) - audit_stabilizer_group("X-check 2q", &[ - gate(GateType::PZ, &[0]), - gate(GateType::PZ, &[1]), - gate(GateType::PZ, &[2]), - gate(GateType::H, &[2]), - gate(GateType::CX, &[2, 0]), - gate(GateType::CX, &[2, 1]), - gate(GateType::H, &[2]), - gate(GateType::MZ, &[2]), - ], 3); + audit_stabilizer_group( + "X-check 2q", + &[ + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + ], + 3, + ); } #[test] fn audit_d2_zbasis_pre_readout() { // d=2 Z-basis surface code, 2 rounds, pre-readout circuit let gates = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), - gate(GateType::PZ, &[2]), gate(GateType::PZ, &[3]), - gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[3]), + gate(GateType::PZ, &[4]), + gate(GateType::PZ, &[5]), gate(GateType::PZ, &[6]), // Round 1 - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), - gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), - gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), - gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), + gate(GateType::CX, &[5, 3]), + gate(GateType::CX, &[3, 6]), + gate(GateType::CX, &[5, 2]), + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[0, 6]), + gate(GateType::CX, &[4, 0]), + gate(GateType::CX, &[2, 6]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), + gate(GateType::MZ, &[5]), gate(GateType::MZ, &[6]), // Reset - gate(GateType::PZ, &[4]), gate(GateType::PZ, &[5]), + gate(GateType::PZ, &[4]), + gate(GateType::PZ, &[5]), gate(GateType::PZ, &[6]), // Round 2 - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::CX, &[1, 6]), gate(GateType::CX, &[5, 3]), - gate(GateType::CX, &[3, 6]), gate(GateType::CX, &[5, 2]), - gate(GateType::CX, &[4, 1]), gate(GateType::CX, &[0, 6]), - gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[2, 6]), - gate(GateType::H, &[4]), gate(GateType::H, &[5]), - gate(GateType::MZ, &[4]), gate(GateType::MZ, &[5]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::CX, &[1, 6]), + gate(GateType::CX, &[5, 3]), + gate(GateType::CX, &[3, 6]), + gate(GateType::CX, &[5, 2]), + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[0, 6]), + gate(GateType::CX, &[4, 0]), + gate(GateType::CX, &[2, 6]), + gate(GateType::H, &[4]), + gate(GateType::H, &[5]), + gate(GateType::MZ, &[4]), + gate(GateType::MZ, &[5]), gate(GateType::MZ, &[6]), ]; audit_stabilizer_group("d=2 Z-basis pre-readout", &gates, 7); diff --git a/exp/pecos-eeg/tests/statevec_comparison.rs b/exp/pecos-eeg/tests/statevec_comparison.rs index f1709623e..08d799d66 100644 --- a/exp/pecos-eeg/tests/statevec_comparison.rs +++ b/exp/pecos-eeg/tests/statevec_comparison.rs @@ -13,8 +13,8 @@ use pecos_core::gate_type::GateType; use pecos_core::pauli::pauli_bitmask::BitmaskStorage; use pecos_core::{Angle64, Gate, GateAngles, GateParams, GateQubits, QubitId}; use pecos_eeg::Bm; -use pecos_eeg::circuit::{analyze_expanded, NoiseModel}; -use pecos_eeg::dem_mapping::{build_dem_with_stabilizers, Detector}; +use pecos_eeg::circuit::{NoiseModel, analyze_expanded}; +use pecos_eeg::dem_mapping::{Detector, build_dem_with_stabilizers}; use pecos_eeg::expand; use pecos_eeg::noise::UniformNoise; use pecos_eeg::stabilizer::StabilizerGroup; @@ -26,7 +26,7 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), angles: GateAngles::new(), params: GateParams::new(), - meas_ids: pecos_core::GateMeasIds::new(), + meas_ids: pecos_core::GateMeasIds::new(), } } @@ -49,18 +49,23 @@ fn eeg_detection_prob(gates: &[Gate], theta: f64) -> f64 { for &aux in &expanded.measurement_qubit { det_stab.z_bits.set_bit(aux); } - let det = Detector { id: 0, stabilizer: det_stab }; + let det = Detector { + id: 0, + stabilizer: det_stab, + }; // Stabilizer group from expanded circuit (strip trailing deferred MZ) let exp_pre: Vec<_> = { - let last = expanded.gates.iter().rposition(|g| g.gate_type != GateType::MZ).unwrap(); + let last = expanded + .gates + .iter() + .rposition(|g| g.gate_type != GateType::MZ) + .unwrap(); expanded.gates[..=last].to_vec() }; let stab_group = StabilizerGroup::from_circuit(&exp_pre, expanded.num_qubits); - let entries = build_dem_with_stabilizers( - &result.generators, &[det], &[], Some(&stab_group), - ); + let entries = build_dem_with_stabilizers(&result.generators, &[det], &[], Some(&stab_group)); entries.iter().map(|e| e.probability).sum() } @@ -72,21 +77,28 @@ fn eeg_per_round_probs(gates: &[Gate], theta: f64, num_rounds: usize) -> Vec = (0..num_rounds).map(|r| { - let aux = expanded.measurement_qubit[r]; - Detector { id: r, stabilizer: Bm::z(aux) } - }).collect(); + let dets: Vec = (0..num_rounds) + .map(|r| { + let aux = expanded.measurement_qubit[r]; + Detector { + id: r, + stabilizer: Bm::z(aux), + } + }) + .collect(); // Stabilizer group from expanded circuit (strip trailing deferred MZ) let exp_pre: Vec<_> = { - let last = expanded.gates.iter().rposition(|g| g.gate_type != GateType::MZ).unwrap(); + let last = expanded + .gates + .iter() + .rposition(|g| g.gate_type != GateType::MZ) + .unwrap(); expanded.gates[..=last].to_vec() }; let stab_group = StabilizerGroup::from_circuit(&exp_pre, expanded.num_qubits); - let entries = build_dem_with_stabilizers( - &result.generators, &dets, &[], Some(&stab_group), - ); + let entries = build_dem_with_stabilizers(&result.generators, &dets, &[], Some(&stab_group)); let mut probs = vec![0.0; num_rounds]; for e in &entries { @@ -131,19 +143,24 @@ fn test_eeg_vs_statevec_bell_parity() { let mut det_stab = Bm::default(); det_stab.z_bits.set_bit(aux0); det_stab.z_bits.set_bit(aux1); - let det = Detector { id: 0, stabilizer: det_stab }; + let det = Detector { + id: 0, + stabilizer: det_stab, + }; // Pre-readout stabilizer group (exclude final MZ gates) // Stabilizer group from expanded circuit (strip trailing deferred MZ) let exp_pre: Vec<_> = { - let last = expanded.gates.iter().rposition(|g| g.gate_type != GateType::MZ).unwrap(); + let last = expanded + .gates + .iter() + .rposition(|g| g.gate_type != GateType::MZ) + .unwrap(); expanded.gates[..=last].to_vec() }; let stab_group = StabilizerGroup::from_circuit(&exp_pre, expanded.num_qubits); - let entries = build_dem_with_stabilizers( - &result.generators, &[det], &[], Some(&stab_group), - ); + let entries = build_dem_with_stabilizers(&result.generators, &[det], &[], Some(&stab_group)); let eeg_prob: f64 = entries.iter().map(|e| e.probability).sum(); @@ -183,8 +200,10 @@ fn test_eeg_vs_statevec_bell_parity() { // Perturbative error is O(θ⁴) ≈ 6.25e-6, well within statistical noise. let diff = (eeg_prob - sv_rate).abs(); let tolerance = 5.0 * sv_stderr + theta.powi(4); // 5σ + perturbative bound - assert!(diff < tolerance, - "EEG ({eeg_prob:.6}) vs StateVec ({sv_rate:.6}): diff={diff:.6} > tol={tolerance:.6}"); + assert!( + diff < tolerance, + "EEG ({eeg_prob:.6}) vs StateVec ({sv_rate:.6}): diff={diff:.6} > tol={tolerance:.6}" + ); } /// Same comparison at larger angle to verify scaling. @@ -213,18 +232,23 @@ fn test_eeg_vs_statevec_larger_angle() { let mut det_stab = Bm::default(); det_stab.z_bits.set_bit(aux0); det_stab.z_bits.set_bit(aux1); - let det = Detector { id: 0, stabilizer: det_stab }; + let det = Detector { + id: 0, + stabilizer: det_stab, + }; // Stabilizer group from expanded circuit (strip trailing deferred MZ) let exp_pre: Vec<_> = { - let last = expanded.gates.iter().rposition(|g| g.gate_type != GateType::MZ).unwrap(); + let last = expanded + .gates + .iter() + .rposition(|g| g.gate_type != GateType::MZ) + .unwrap(); expanded.gates[..=last].to_vec() }; let stab_group = StabilizerGroup::from_circuit(&exp_pre, expanded.num_qubits); - let entries = build_dem_with_stabilizers( - &result.generators, &[det], &[], Some(&stab_group), - ); + let entries = build_dem_with_stabilizers(&result.generators, &[det], &[], Some(&stab_group)); let eeg_prob: f64 = entries.iter().map(|e| e.probability).sum(); @@ -258,8 +282,10 @@ fn test_eeg_vs_statevec_larger_angle() { // Allow larger tolerance for bigger angle let diff = (eeg_prob - sv_rate).abs(); let tolerance = 5.0 * sv_stderr + 2.0 * theta.powi(4); - assert!(diff < tolerance, - "EEG ({eeg_prob:.6}) vs StateVec ({sv_rate:.6}): diff={diff:.6} > tol={tolerance:.6}"); + assert!( + diff < tolerance, + "EEG ({eeg_prob:.6}) vs StateVec ({sv_rate:.6}): diff={diff:.6} > tol={tolerance:.6}" + ); } // ============================================================ @@ -285,8 +311,10 @@ fn bench_bell_parity_theta_sweep() { ]; eprintln!("\n=== Bell parity: EEG vs StateVec vs Exact ==="); - eprintln!("{:>8} {:>10} {:>10} {:>10} {:>10} {:>10}", - "theta", "EEG", "StateVec", "SV_stderr", "Exact", "EEG/Exact"); + eprintln!( + "{:>8} {:>10} {:>10} {:>10} {:>10} {:>10}", + "theta", "EEG", "StateVec", "SV_stderr", "Exact", "EEG/Exact" + ); for &theta in &[0.01, 0.02, 0.05, 0.1, 0.15, 0.2, 0.3, 0.5] { let eeg_prob = eeg_detection_prob(&gates, theta); @@ -302,15 +330,23 @@ fn bench_bell_parity_theta_sweep() { sim.h(&[qid(0)]); sim.h(&[qid(1)]); let r = sim.mz(&[qid(0), qid(1)]); - if r[0].outcome != r[1].outcome { odd += 1; } + if r[0].outcome != r[1].outcome { + odd += 1; + } } let sv = odd as f64 / num_shots as f64; let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); let exact = theta.sin().powi(2); - let ratio = if exact > 1e-10 { eeg_prob / exact } else { f64::NAN }; - - eprintln!("{theta:>8.3} {eeg_prob:>10.6} {sv:>10.6} {se:>10.6} {exact:>10.6} {ratio:>10.4}"); + let ratio = if exact > 1e-10 { + eeg_prob / exact + } else { + f64::NAN + }; + + eprintln!( + "{theta:>8.3} {eeg_prob:>10.6} {sv:>10.6} {se:>10.6} {exact:>10.6} {ratio:>10.4}" + ); } } @@ -375,15 +411,23 @@ fn bench_x_check_multi_round() { } } - let sv_rates: Vec = round_detections.iter() - .map(|&d| d as f64 / num_shots as f64).collect(); + let sv_rates: Vec = round_detections + .iter() + .map(|&d| d as f64 / num_shots as f64) + .collect(); eprintln!("\nrounds={num_rounds}, theta={theta}:"); for r in 0..num_rounds { let se = (sv_rates[r] * (1.0 - sv_rates[r]) / num_shots as f64).sqrt(); - let ratio = if sv_rates[r] > 1e-10 { eeg_probs[r] / sv_rates[r] } else { f64::NAN }; - eprintln!(" D{r}: EEG={:.6} SV={:.6}+/-{:.6} ratio={:.4}", - eeg_probs[r], sv_rates[r], se, ratio); + let ratio = if sv_rates[r] > 1e-10 { + eeg_probs[r] / sv_rates[r] + } else { + f64::NAN + }; + eprintln!( + " D{r}: EEG={:.6} SV={:.6}+/-{:.6} ratio={:.4}", + eeg_probs[r], sv_rates[r], se, ratio + ); } } } @@ -397,8 +441,10 @@ fn bench_z_basis_check() { let num_shots = 200_000; eprintln!("\n=== Z-basis parity check (CX syndrome extraction) ==="); - eprintln!("{:>8} {:>10} {:>10} {:>10} {:>10}", - "theta", "EEG", "StateVec", "SV_stderr", "EEG/SV"); + eprintln!( + "{:>8} {:>10} {:>10} {:>10} {:>10}", + "theta", "EEG", "StateVec", "SV_stderr", "EEG/SV" + ); // Z-check: CX(0,2), CX(1,2), MZ(2). Ancilla 2 measures Z0*Z1 parity. // For |00>: Z0Z1|00> = +|00>, deterministic 0. @@ -419,12 +465,14 @@ fn bench_z_basis_check() { let result = analyze_expanded(&expanded.gates, &noise); let aux = expanded.measurement_qubit[0]; - let det = Detector { id: 0, stabilizer: Bm::z(aux) }; + let det = Detector { + id: 0, + stabilizer: Bm::z(aux), + }; let gates_pre = &gates[..gates.len() - 1]; let stab_group = StabilizerGroup::from_circuit(gates_pre, expanded.num_original_qubits); - let entries = build_dem_with_stabilizers( - &result.generators, &[det], &[], Some(&stab_group), - ); + let entries = + build_dem_with_stabilizers(&result.generators, &[det], &[], Some(&stab_group)); let eeg_prob: f64 = entries.iter().map(|e| e.probability).sum(); // StateVec @@ -439,7 +487,9 @@ fn bench_z_basis_check() { sim.rz(Angle64::from_radians(theta), &[qid(1)]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); let r = sim.mz(&[qid(2)]); - if r[0].outcome { det_count += 1; } + if r[0].outcome { + det_count += 1; + } } let sv = det_count as f64 / num_shots as f64; @@ -536,7 +586,9 @@ fn bench_repetition_code_comparison() { // Round comparison detectors: meas[round*num_ancilla + i] XOR meas[(round+1)*num_ancilla + i] let num_detectors = num_ancilla * (num_rounds - 1); - eprintln!("\n d={d}, rounds={num_rounds}, qubits={num_qubits}, detectors={num_detectors}"); + eprintln!( + "\n d={d}, rounds={num_rounds}, qubits={num_qubits}, detectors={num_detectors}" + ); // --- EEG forward --- let expanded = expand::expand_circuit(&gates); @@ -554,19 +606,29 @@ fn bench_repetition_code_comparison() { let mut stab = Bm::default(); stab.z_bits.set_bit(aux1); stab.z_bits.set_bit(aux2); - dets.push(Detector { id: dets.len(), stabilizer: stab }); + dets.push(Detector { + id: dets.len(), + stabilizer: stab, + }); } } let exp_pre: Vec<_> = { - let last = expanded.gates.iter().rposition(|g| g.gate_type != GateType::MZ).unwrap(); + let last = expanded + .gates + .iter() + .rposition(|g| g.gate_type != GateType::MZ) + .unwrap(); expanded.gates[..=last].to_vec() }; let stab_group = StabilizerGroup::from_circuit(&exp_pre, expanded.num_qubits); let entries = pecos_eeg::dem_mapping::build_dem_configured( - &result.generators, &dets, &[], - Some(&stab_group), &EegConfig::default(), + &result.generators, + &dets, + &[], + Some(&stab_group), + &EegConfig::default(), ); let mut eeg_probs = vec![0.0; num_detectors]; @@ -586,7 +648,11 @@ fn bench_repetition_code_comparison() { let m1 = round * num_ancilla + i; let m2 = (round + 1) * num_ancilla + i; heis_probs[det_idx] = heisenberg_detection_probability_from_circuit( - &gates, &[m1, m2], &noise_spec, num_qubits, 1e-12, + &gates, + &[m1, m2], + &noise_spec, + num_qubits, + 1e-12, ); } } @@ -647,16 +713,24 @@ fn bench_repetition_code_comparison() { } // Print comparison - eprintln!(" {:>6} {:>10} {:>10} {:>10} {:>10} {:>10}", - "Det", "EEG", "Heisen", "StateVec", "SV_err", "H/SV"); + eprintln!( + " {:>6} {:>10} {:>10} {:>10} {:>10} {:>10}", + "Det", "EEG", "Heisen", "StateVec", "SV_err", "H/SV" + ); for det_idx in 0..num_detectors { let sv_rate = sv_counts[det_idx] as f64 / num_shots as f64; let sv_err = (sv_rate * (1.0 - sv_rate) / num_shots as f64).sqrt(); - let ratio = if sv_rate > 1e-10 { heis_probs[det_idx] / sv_rate } else { f64::NAN }; + let ratio = if sv_rate > 1e-10 { + heis_probs[det_idx] / sv_rate + } else { + f64::NAN + }; let round = det_idx / num_ancilla; let anc = det_idx % num_ancilla; - eprintln!(" R{round}A{anc} {:>10.6} {:>10.6} {:>10.6} {:>10.6} {:>10.4}", - eeg_probs[det_idx], heis_probs[det_idx], sv_rate, sv_err, ratio); + eprintln!( + " R{round}A{anc} {:>10.6} {:>10.6} {:>10.6} {:>10.6} {:>10.4}", + eeg_probs[det_idx], heis_probs[det_idx], sv_rate, sv_err, ratio + ); } } } @@ -679,7 +753,9 @@ fn bench_expansion_equivalence() { // Original circuit with mid-circuit measurement let gates_orig = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), gate(GateType::H, &[2]), gate(GateType::CX, &[2, 0]), gate(GateType::CX, &[2, 1]), @@ -695,7 +771,11 @@ fn bench_expansion_equivalence() { // Expand the circuit let expanded = expand::expand_circuit(&gates_orig); - eprintln!("Expanded: {} gates, {} qubits", expanded.gates.len(), expanded.num_qubits); + eprintln!( + "Expanded: {} gates, {} qubits", + expanded.gates.len(), + expanded.num_qubits + ); eprintln!("Measurement map: {:?}", expanded.measurement_qubit); for (i, g) in expanded.gates.iter().enumerate() { let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); @@ -715,13 +795,21 @@ fn bench_expansion_equivalence() { let mut outs = [false; 2]; for r in 0..2 { sim.h(&[qid(2)]); - sim.cx(&[(qid(2), qid(0))]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.rz(Angle64::from_radians(theta), &[qid(0)]); - sim.cx(&[(qid(2), qid(1))]); sim.rz(Angle64::from_radians(theta), &[qid(1)]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.cx(&[(qid(2), qid(0))]); + sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.cx(&[(qid(2), qid(1))]); + sim.rz(Angle64::from_radians(theta), &[qid(1)]); + sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.h(&[qid(2)]); outs[r] = sim.mz(&[qid(2)])[0].outcome; - if r == 0 { sim.pz(&[qid(2)]); } + if r == 0 { + sim.pz(&[qid(2)]); + } + } + if outs[0] != outs[1] { + orig_det += 1; } - if outs[0] != outs[1] { orig_det += 1; } } } let sv_orig = orig_det as f64 / num_shots as f64; @@ -744,21 +832,29 @@ fn bench_expansion_equivalence() { let is_qalloc = g.gate_type == pecos_core::gate_type::GateType::QAlloc; let is_exp_cx = i > 0 && g.gate_type == pecos_core::gate_type::GateType::CX - && expanded.gates[i-1].gate_type == pecos_core::gate_type::GateType::QAlloc - && expanded.gates[i-1].qubits[0].index() == qs.get(1).copied().unwrap_or(999); + && expanded.gates[i - 1].gate_type + == pecos_core::gate_type::GateType::QAlloc + && expanded.gates[i - 1].qubits[0].index() + == qs.get(1).copied().unwrap_or(999); let is_exp_pz = i > 1 && g.gate_type == pecos_core::gate_type::GateType::PZ - && expanded.gates[i-1].gate_type == pecos_core::gate_type::GateType::CX - && expanded.gates[i-2].gate_type == pecos_core::gate_type::GateType::QAlloc; + && expanded.gates[i - 1].gate_type == pecos_core::gate_type::GateType::CX + && expanded.gates[i - 2].gate_type + == pecos_core::gate_type::GateType::QAlloc; is_qalloc || is_exp_cx || is_exp_pz }; match g.gate_type { - pecos_core::gate_type::GateType::PZ | pecos_core::gate_type::GateType::QAlloc => { - for &q in &qs { sim.pz(&[qid(q)]); } + pecos_core::gate_type::GateType::PZ + | pecos_core::gate_type::GateType::QAlloc => { + for &q in &qs { + sim.pz(&[qid(q)]); + } } pecos_core::gate_type::GateType::H => { - for &q in &qs { sim.h(&[qid(q)]); } + for &q in &qs { + sim.h(&[qid(q)]); + } } pecos_core::gate_type::GateType::CX => { if qs.len() >= 2 { @@ -785,7 +881,9 @@ fn bench_expansion_equivalence() { let aux1 = expanded.measurement_qubit[1]; let r0 = sim.mz(&[qid(aux0)])[0].outcome; let r1 = sim.mz(&[qid(aux1)])[0].outcome; - if r0 != r1 { exp_det += 1; } + if r0 != r1 { + exp_det += 1; + } } } let sv_exp = exp_det as f64 / num_shots as f64; @@ -825,7 +923,9 @@ fn bench_matrix_heisenberg() { // The expanded circuit gates (from bench_expansion_equivalence) let gates_orig = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), gate(GateType::H, &[2]), gate(GateType::CX, &[2, 0]), gate(GateType::CX, &[2, 1]), @@ -876,16 +976,18 @@ fn bench_matrix_heisenberg() { s.insert(i); } if expanded.gates[i].gate_type == pecos_core::gate_type::GateType::CX - && expanded.gates[i-1].gate_type == pecos_core::gate_type::GateType::QAlloc + && expanded.gates[i - 1].gate_type == pecos_core::gate_type::GateType::QAlloc { - let aq = expanded.gates[i-1].qubits[0].index(); - if expanded.gates[i].qubits.len() >= 2 && expanded.gates[i].qubits[1].index() == aq { + let aq = expanded.gates[i - 1].qubits[0].index(); + if expanded.gates[i].qubits.len() >= 2 && expanded.gates[i].qubits[1].index() == aq + { s.insert(i); - if i+1 < expanded.gates.len() - && expanded.gates[i+1].gate_type == pecos_core::gate_type::GateType::PZ - && expanded.gates[i+1].qubits[0].index() == expanded.gates[i].qubits[0].index() + if i + 1 < expanded.gates.len() + && expanded.gates[i + 1].gate_type == pecos_core::gate_type::GateType::PZ + && expanded.gates[i + 1].qubits[0].index() + == expanded.gates[i].qubits[0].index() { - s.insert(i+1); + s.insert(i + 1); } } } @@ -948,7 +1050,10 @@ fn bench_matrix_heisenberg() { } eprintln!("\n Step-by-step <0|O|0> comparison (matrix vs walk):"); - eprintln!(" {:>4} {:>20} {:>12}", "Gate", "Description", "Matrix<0|O|0>"); + eprintln!( + " {:>4} {:>20} {:>12}", + "Gate", "Description", "Matrix<0|O|0>" + ); for idx in (0..expanded.gates.len()).rev() { let g = &expanded.gates[idx]; @@ -981,8 +1086,7 @@ fn bench_matrix_heisenberg() { let e = tr_re[0]; let tag = if is_exp { " [EXP]" } else { "" }; - eprintln!(" [{idx:>2}] {:?}({qs:?}){tag}: {e:.10}", - g.gate_type); + eprintln!(" [{idx:>2}] {:?}({qs:?}){tag}: {e:.10}", g.gate_type); } } @@ -1012,7 +1116,9 @@ fn apply_rz_adjoint(re: &mut [f64], im: &mut [f64], q: usize, theta: f64, n: usi for j in 0..dim { let bj = ((j >> q) & 1) as f64; let phase = (bi - bj) * theta; // phase angle - if phase.abs() < 1e-20 { continue; } + if phase.abs() < 1e-20 { + continue; + } let cp = phase.cos(); let sp = phase.sin(); let idx = i * dim + j; @@ -1093,7 +1199,11 @@ fn apply_h_adjoint(re: &mut [f64], im: &mut [f64], q: usize, n: usize) { let ia = if a == 0 { i0 } else { i1 }; let jb = if b == 0 { j0 } else { j1 }; let idx = ia * dim + jb; - let sign = if (iq * a + b * jq) % 2 == 0 { 1.0 } else { -1.0 }; + let sign = if (iq * a + b * jq) % 2 == 0 { + 1.0 + } else { + -1.0 + }; let c = 0.5 * sign; sum_r += c * re[idx]; sum_i += c * im[idx]; @@ -1114,9 +1224,7 @@ fn apply_cx_adjoint(re: &mut [f64], im: &mut [f64], control: usize, target: usiz let cmask = 1 << control; let tmask = 1 << target; // CX permutation: state index i maps to i ^ (tmask if control bit set) - let cx_perm = |i: usize| -> usize { - if (i & cmask) != 0 { i ^ tmask } else { i } - }; + let cx_perm = |i: usize| -> usize { if (i & cmask) != 0 { i ^ tmask } else { i } }; // O' = CX · O · CX: new O[i,j] = O[CX(i), CX(j)] let mut new_re = vec![0.0; dim * dim]; let mut new_im = vec![0.0; dim * dim]; @@ -1145,7 +1253,9 @@ fn bench_per_noise_attribution() { let dim = 1 << n; let gates_orig = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), gate(GateType::H, &[2]), gate(GateType::CX, &[2, 0]), gate(GateType::CX, &[2, 1]), @@ -1177,7 +1287,10 @@ fn bench_per_noise_attribution() { ]; eprintln!("\n=== Per-noise-source attribution ==="); - eprintln!("{:>25} {:>12} {:>12} {:>8}", "Source", "Matrix", "Walk", "Ratio"); + eprintln!( + "{:>25} {:>12} {:>12} {:>8}", + "Source", "Matrix", "Walk", "Ratio" + ); for &(gate_idx, qubit, label) in &noise_sources { // Matrix computation with only this one noise source @@ -1238,8 +1351,8 @@ fn bench_per_noise_attribution() { if g.gate_type == pecos_core::gate_type::GateType::CX && qs.len() >= 2 { // Check if expansion gate let is_exp = idx > 0 - && expanded.gates[idx-1].gate_type == pecos_core::gate_type::GateType::QAlloc - && expanded.gates[idx-1].qubits[0].index() == qs[1]; + && expanded.gates[idx - 1].gate_type == pecos_core::gate_type::GateType::QAlloc + && expanded.gates[idx - 1].qubits[0].index() == qs[1]; if !is_exp { apply_rz_adjoint(&mut obs_re, &mut obs_im, qs[0], theta, n); apply_rz_adjoint(&mut obs_re, &mut obs_im, qs[1], theta, n); @@ -1263,8 +1376,15 @@ fn bench_per_noise_attribution() { } let matrix_all = 0.5 * (1.0 - obs_re[0]); let noise = UniformNoise::coherent_only(theta); - let walk_all = heisenberg_detection_probability_from_circuit(&gates_orig, &[0, 1], &noise, 3, 0.0); - eprintln!("{:>25} {:>12.8} {:>12.8} {:>8.4}", "ALL", matrix_all, walk_all, walk_all / matrix_all); + let walk_all = + heisenberg_detection_probability_from_circuit(&gates_orig, &[0, 1], &noise, 3, 0.0); + eprintln!( + "{:>25} {:>12.8} {:>12.8} {:>8.4}", + "ALL", + matrix_all, + walk_all, + walk_all / matrix_all + ); } /// Isolate weight-2 vs weight-4 X-check, single vs multi-round. @@ -1282,7 +1402,9 @@ fn bench_weight_isolation() { // ---- Weight-2, 1 round: H(2), CX(2,0), CX(2,1), H(2), MZ(2) ---- { let gates = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), gate(GateType::H, &[2]), gate(GateType::CX, &[2, 0]), gate(GateType::CX, &[2, 1]), @@ -1297,23 +1419,41 @@ fn bench_weight_isolation() { for _ in 0..num_shots { sim.pz(&[qid(0), qid(1), qid(2)]); sim.h(&[qid(2)]); - sim.cx(&[(qid(2), qid(0))]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.rz(Angle64::from_radians(theta), &[qid(0)]); - sim.cx(&[(qid(2), qid(1))]); sim.rz(Angle64::from_radians(theta), &[qid(1)]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.cx(&[(qid(2), qid(0))]); + sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.cx(&[(qid(2), qid(1))]); + sim.rz(Angle64::from_radians(theta), &[qid(1)]); + sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.h(&[qid(2)]); - if sim.mz(&[qid(2)])[0].outcome { det += 1; } + if sim.mz(&[qid(2)])[0].outcome { + det += 1; + } } let sv = det as f64 / num_shots as f64; let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); - eprintln!("Wt-2 1rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", if sv > 1e-10 { h_p/sv } else { f64::NAN }); + eprintln!( + "Wt-2 1rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", + if sv > 1e-10 { h_p / sv } else { f64::NAN } + ); } // ---- Weight-2, 2 rounds: round comparison ---- { let gates = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), - gate(GateType::H, &[2]), gate(GateType::CX, &[2, 0]), gate(GateType::CX, &[2, 1]), gate(GateType::H, &[2]), - gate(GateType::MZ, &[2]), gate(GateType::PZ, &[2]), - gate(GateType::H, &[2]), gate(GateType::CX, &[2, 0]), gate(GateType::CX, &[2, 1]), gate(GateType::H, &[2]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), + gate(GateType::MZ, &[2]), + gate(GateType::PZ, &[2]), + gate(GateType::H, &[2]), + gate(GateType::CX, &[2, 0]), + gate(GateType::CX, &[2, 1]), + gate(GateType::H, &[2]), gate(GateType::MZ, &[2]), ]; let noise = UniformNoise::coherent_only(theta); @@ -1326,27 +1466,43 @@ fn bench_weight_isolation() { let mut outs = [false; 2]; for r in 0..2 { sim.h(&[qid(2)]); - sim.cx(&[(qid(2), qid(0))]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.rz(Angle64::from_radians(theta), &[qid(0)]); - sim.cx(&[(qid(2), qid(1))]); sim.rz(Angle64::from_radians(theta), &[qid(1)]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.cx(&[(qid(2), qid(0))]); + sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.cx(&[(qid(2), qid(1))]); + sim.rz(Angle64::from_radians(theta), &[qid(1)]); + sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.h(&[qid(2)]); outs[r] = sim.mz(&[qid(2)])[0].outcome; - if r == 0 { sim.pz(&[qid(2)]); } + if r == 0 { + sim.pz(&[qid(2)]); + } + } + if outs[0] != outs[1] { + det += 1; } - if outs[0] != outs[1] { det += 1; } } let sv = det as f64 / num_shots as f64; let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); - eprintln!("Wt-2 2rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", if sv > 1e-10 { h_p/sv } else { f64::NAN }); + eprintln!( + "Wt-2 2rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", + if sv > 1e-10 { h_p / sv } else { f64::NAN } + ); } // ---- Weight-4, 1 round ---- { let gates = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), - gate(GateType::PZ, &[2]), gate(GateType::PZ, &[3]), gate(GateType::PZ, &[4]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[3]), + gate(GateType::PZ, &[4]), gate(GateType::H, &[4]), - gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[4, 1]), - gate(GateType::CX, &[4, 2]), gate(GateType::CX, &[4, 3]), + gate(GateType::CX, &[4, 0]), + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[4, 2]), + gate(GateType::CX, &[4, 3]), gate(GateType::H, &[4]), gate(GateType::MZ, &[4]), ]; @@ -1359,29 +1515,44 @@ fn bench_weight_isolation() { sim.pz(&[qid(0), qid(1), qid(2), qid(3), qid(4)]); sim.h(&[qid(4)]); for &d in &[0usize, 1, 2, 3] { - sim.cx(&[(qid(4), qid(d))]); sim.rz(Angle64::from_radians(theta), &[qid(4)]); sim.rz(Angle64::from_radians(theta), &[qid(d)]); + sim.cx(&[(qid(4), qid(d))]); + sim.rz(Angle64::from_radians(theta), &[qid(4)]); + sim.rz(Angle64::from_radians(theta), &[qid(d)]); } sim.h(&[qid(4)]); - if sim.mz(&[qid(4)])[0].outcome { det += 1; } + if sim.mz(&[qid(4)])[0].outcome { + det += 1; + } } let sv = det as f64 / num_shots as f64; let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); - eprintln!("Wt-4 1rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", if sv > 1e-10 { h_p/sv } else { f64::NAN }); + eprintln!( + "Wt-4 1rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", + if sv > 1e-10 { h_p / sv } else { f64::NAN } + ); } // ---- Weight-4, 2 rounds ---- { let gates = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), - gate(GateType::PZ, &[2]), gate(GateType::PZ, &[3]), gate(GateType::PZ, &[4]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[3]), + gate(GateType::PZ, &[4]), gate(GateType::H, &[4]), - gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[4, 1]), - gate(GateType::CX, &[4, 2]), gate(GateType::CX, &[4, 3]), + gate(GateType::CX, &[4, 0]), + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[4, 2]), + gate(GateType::CX, &[4, 3]), gate(GateType::H, &[4]), - gate(GateType::MZ, &[4]), gate(GateType::PZ, &[4]), + gate(GateType::MZ, &[4]), + gate(GateType::PZ, &[4]), gate(GateType::H, &[4]), - gate(GateType::CX, &[4, 0]), gate(GateType::CX, &[4, 1]), - gate(GateType::CX, &[4, 2]), gate(GateType::CX, &[4, 3]), + gate(GateType::CX, &[4, 0]), + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[4, 2]), + gate(GateType::CX, &[4, 3]), gate(GateType::H, &[4]), gate(GateType::MZ, &[4]), ]; @@ -1396,38 +1567,61 @@ fn bench_weight_isolation() { for r in 0..2 { sim.h(&[qid(4)]); for &d in &[0usize, 1, 2, 3] { - sim.cx(&[(qid(4), qid(d))]); sim.rz(Angle64::from_radians(theta), &[qid(4)]); sim.rz(Angle64::from_radians(theta), &[qid(d)]); + sim.cx(&[(qid(4), qid(d))]); + sim.rz(Angle64::from_radians(theta), &[qid(4)]); + sim.rz(Angle64::from_radians(theta), &[qid(d)]); } sim.h(&[qid(4)]); outs[r] = sim.mz(&[qid(4)])[0].outcome; - if r == 0 { sim.pz(&[qid(4)]); } + if r == 0 { + sim.pz(&[qid(4)]); + } + } + if outs[0] != outs[1] { + det += 1; } - if outs[0] != outs[1] { det += 1; } } let sv = det as f64 / num_shots as f64; let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); - eprintln!("Wt-4 2rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", if sv > 1e-10 { h_p/sv } else { f64::NAN }); + eprintln!( + "Wt-4 2rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", + if sv > 1e-10 { h_p / sv } else { f64::NAN } + ); } eprintln!(); // ---- 2 weight-2 ancillas sharing a data qubit, 2 rounds ---- { let gates = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), - gate(GateType::PZ, &[3]), gate(GateType::PZ, &[4]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[3]), + gate(GateType::PZ, &[4]), // Round 1 - gate(GateType::H, &[3]), gate(GateType::H, &[4]), - gate(GateType::CX, &[3, 0]), gate(GateType::CX, &[4, 1]), - gate(GateType::CX, &[3, 1]), gate(GateType::CX, &[4, 2]), - gate(GateType::H, &[3]), gate(GateType::H, &[4]), - gate(GateType::MZ, &[3]), gate(GateType::MZ, &[4]), - gate(GateType::PZ, &[3]), gate(GateType::PZ, &[4]), + gate(GateType::H, &[3]), + gate(GateType::H, &[4]), + gate(GateType::CX, &[3, 0]), + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[3, 1]), + gate(GateType::CX, &[4, 2]), + gate(GateType::H, &[3]), + gate(GateType::H, &[4]), + gate(GateType::MZ, &[3]), + gate(GateType::MZ, &[4]), + gate(GateType::PZ, &[3]), + gate(GateType::PZ, &[4]), // Round 2 - gate(GateType::H, &[3]), gate(GateType::H, &[4]), - gate(GateType::CX, &[3, 0]), gate(GateType::CX, &[4, 1]), - gate(GateType::CX, &[3, 1]), gate(GateType::CX, &[4, 2]), - gate(GateType::H, &[3]), gate(GateType::H, &[4]), - gate(GateType::MZ, &[3]), gate(GateType::MZ, &[4]), + gate(GateType::H, &[3]), + gate(GateType::H, &[4]), + gate(GateType::CX, &[3, 0]), + gate(GateType::CX, &[4, 1]), + gate(GateType::CX, &[3, 1]), + gate(GateType::CX, &[4, 2]), + gate(GateType::H, &[3]), + gate(GateType::H, &[4]), + gate(GateType::MZ, &[3]), + gate(GateType::MZ, &[4]), ]; let noise = UniformNoise::coherent_only(theta); let h_a0 = heisenberg_detection_probability_from_circuit(&gates, &[0, 2], &noise, 5, 0.0); @@ -1441,24 +1635,44 @@ fn bench_weight_isolation() { let mut outs = [false; 4]; // [r0a0, r0a1, r1a0, r1a1] for r in 0..2 { sim.h(&[qid(3), qid(4)]); - sim.cx(&[(qid(3), qid(0))]); sim.rz(Angle64::from_radians(theta), &[qid(3)]); sim.rz(Angle64::from_radians(theta), &[qid(0)]); - sim.cx(&[(qid(4), qid(1))]); sim.rz(Angle64::from_radians(theta), &[qid(4)]); sim.rz(Angle64::from_radians(theta), &[qid(1)]); - sim.cx(&[(qid(3), qid(1))]); sim.rz(Angle64::from_radians(theta), &[qid(3)]); sim.rz(Angle64::from_radians(theta), &[qid(1)]); - sim.cx(&[(qid(4), qid(2))]); sim.rz(Angle64::from_radians(theta), &[qid(4)]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); + sim.cx(&[(qid(3), qid(0))]); + sim.rz(Angle64::from_radians(theta), &[qid(3)]); + sim.rz(Angle64::from_radians(theta), &[qid(0)]); + sim.cx(&[(qid(4), qid(1))]); + sim.rz(Angle64::from_radians(theta), &[qid(4)]); + sim.rz(Angle64::from_radians(theta), &[qid(1)]); + sim.cx(&[(qid(3), qid(1))]); + sim.rz(Angle64::from_radians(theta), &[qid(3)]); + sim.rz(Angle64::from_radians(theta), &[qid(1)]); + sim.cx(&[(qid(4), qid(2))]); + sim.rz(Angle64::from_radians(theta), &[qid(4)]); + sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.h(&[qid(3), qid(4)]); outs[r * 2] = sim.mz(&[qid(3)])[0].outcome; outs[r * 2 + 1] = sim.mz(&[qid(4)])[0].outcome; - if r == 0 { sim.pz(&[qid(3), qid(4)]); } + if r == 0 { + sim.pz(&[qid(3), qid(4)]); + } + } + if outs[0] != outs[2] { + a0 += 1; + } + if outs[1] != outs[3] { + a1 += 1; } - if outs[0] != outs[2] { a0 += 1; } - if outs[1] != outs[3] { a1 += 1; } } let sv0 = a0 as f64 / num_shots as f64; let sv1 = a1 as f64 / num_shots as f64; let se0 = (sv0 * (1.0 - sv0) / num_shots as f64).sqrt(); let se1 = (sv1 * (1.0 - sv1) / num_shots as f64).sqrt(); - eprintln!("Shared A0: H={h_a0:.6} SV={sv0:.6}+/-{se0:.6} H/SV={:.4}", if sv0 > 1e-10 { h_a0/sv0 } else { f64::NAN }); - eprintln!("Shared A1: H={h_a1:.6} SV={sv1:.6}+/-{se1:.6} H/SV={:.4}", if sv1 > 1e-10 { h_a1/sv1 } else { f64::NAN }); + eprintln!( + "Shared A0: H={h_a0:.6} SV={sv0:.6}+/-{se0:.6} H/SV={:.4}", + if sv0 > 1e-10 { h_a0 / sv0 } else { f64::NAN } + ); + eprintln!( + "Shared A1: H={h_a1:.6} SV={sv1:.6}+/-{se1:.6} H/SV={:.4}", + if sv1 > 1e-10 { h_a1 / sv1 } else { f64::NAN } + ); } } @@ -1481,8 +1695,10 @@ fn bench_heisenberg_scaling() { // --- Part 1: Vary distance at fixed rounds=2 --- eprintln!("\n=== Heisenberg scaling: distance sweep (rounds=2, all detectors) ==="); - eprintln!("{:>4} {:>10} {:>14} {:>6} {:>18} {:>12} {:>12} {:>12}", - "d", "num_qubits", "expanded_q", "n_det", "max_prob", "max_ms", "total_ms", "per_det_ms"); + eprintln!( + "{:>4} {:>10} {:>14} {:>6} {:>18} {:>12} {:>12} {:>12}", + "d", "num_qubits", "expanded_q", "n_det", "max_prob", "max_ms", "total_ms", "per_det_ms" + ); for &d in &[3, 5, 7, 9] { let num_rounds = 2; @@ -1507,7 +1723,11 @@ fn bench_heisenberg_scaling() { let start = Instant::now(); let prob = heisenberg_detection_probability_from_circuit( - &gates, &[m1, m2], &noise, num_qubits, 0.0, + &gates, + &[m1, m2], + &noise, + num_qubits, + 0.0, ); let elapsed_ms = start.elapsed().as_secs_f64() * 1000.0; @@ -1519,14 +1739,25 @@ fn bench_heisenberg_scaling() { } let per_det = total_ms / num_detectors as f64; - eprintln!("{d:>4} {num_qubits:>10} {:>14} {num_detectors:>6} {max_prob:>18.10} {max_ms:>12.2} {total_ms:>12.2} {per_det:>12.2}", - expanded.num_qubits); + eprintln!( + "{d:>4} {num_qubits:>10} {:>14} {num_detectors:>6} {max_prob:>18.10} {max_ms:>12.2} {total_ms:>12.2} {per_det:>12.2}", + expanded.num_qubits + ); } // --- Part 2: Vary rounds at fixed d=3 --- eprintln!("\n=== Heisenberg scaling: rounds sweep (d=3, all detectors) ==="); - eprintln!("{:>6} {:>10} {:>14} {:>6} {:>18} {:>12} {:>12} {:>12}", - "rounds", "num_qubits", "expanded_q", "n_det", "max_prob", "max_ms", "total_ms", "per_det_ms"); + eprintln!( + "{:>6} {:>10} {:>14} {:>6} {:>18} {:>12} {:>12} {:>12}", + "rounds", + "num_qubits", + "expanded_q", + "n_det", + "max_prob", + "max_ms", + "total_ms", + "per_det_ms" + ); for &num_rounds in &[2, 3, 4, 5] { let d = 3; @@ -1552,7 +1783,11 @@ fn bench_heisenberg_scaling() { let start = Instant::now(); let prob = heisenberg_detection_probability_from_circuit( - &gates, &[m1, m2], &noise, num_qubits, 0.0, + &gates, + &[m1, m2], + &noise, + num_qubits, + 0.0, ); let elapsed_ms = start.elapsed().as_secs_f64() * 1000.0; @@ -1565,8 +1800,10 @@ fn bench_heisenberg_scaling() { } let per_det = total_ms / num_detectors as f64; - eprintln!("{num_rounds:>6} {num_qubits:>10} {:>14} {num_detectors:>6} {max_prob:>18.10} {max_ms:>12.2} {total_ms:>12.2} {per_det:>12.2}", - expanded.num_qubits); + eprintln!( + "{num_rounds:>6} {num_qubits:>10} {:>14} {num_detectors:>6} {max_prob:>18.10} {max_ms:>12.2} {total_ms:>12.2} {per_det:>12.2}", + expanded.num_qubits + ); } } @@ -1596,7 +1833,9 @@ fn bench_combined_noise() { // ---- Build the circuit: 2 data (q0,q1) + 1 ancilla (q2), 2 rounds ---- let gates = vec![ - gate(GateType::PZ, &[0]), gate(GateType::PZ, &[1]), gate(GateType::PZ, &[2]), + gate(GateType::PZ, &[0]), + gate(GateType::PZ, &[1]), + gate(GateType::PZ, &[2]), // Round 1 gate(GateType::H, &[2]), gate(GateType::CX, &[2, 0]), @@ -1613,7 +1852,13 @@ fn bench_combined_noise() { ]; // ---- Heisenberg walk with combined noise ---- - let noise = UniformNoise { idle_rz, p1: 0.0, p2: 0.0, p_meas, p_prep: 0.0 }; + let noise = UniformNoise { + idle_rz, + p1: 0.0, + p2: 0.0, + p_meas, + p_prep: 0.0, + }; // Detector = Z on meas[0] * Z on meas[1] (round comparison) let h_p = heisenberg_detection_probability_from_circuit(&gates, &[0, 1], &noise, 3, 0.0); @@ -1621,8 +1866,15 @@ fn bench_combined_noise() { let noise_coh = UniformNoise::coherent_only(idle_rz); let h_coh = heisenberg_detection_probability_from_circuit(&gates, &[0, 1], &noise_coh, 3, 0.0); - let noise_meas = UniformNoise { idle_rz: 0.0, p1: 0.0, p2: 0.0, p_meas, p_prep: 0.0 }; - let h_meas = heisenberg_detection_probability_from_circuit(&gates, &[0, 1], &noise_meas, 3, 0.0); + let noise_meas = UniformNoise { + idle_rz: 0.0, + p1: 0.0, + p2: 0.0, + p_meas, + p_prep: 0.0, + }; + let h_meas = + heisenberg_detection_probability_from_circuit(&gates, &[0, 1], &noise_meas, 3, 0.0); // ---- StateVec simulation with matching noise ---- let mut rng = PecosRng::seed_from_u64(12345); @@ -1650,9 +1902,13 @@ fn bench_combined_noise() { outcome = !outcome; } outs[r] = outcome; - if r == 0 { sim.pz(&[qid(2)]); } + if r == 0 { + sim.pz(&[qid(2)]); + } + } + if outs[0] != outs[1] { + det += 1; } - if outs[0] != outs[1] { det += 1; } } let sv = det as f64 / num_shots as f64; let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); @@ -1666,11 +1922,19 @@ fn bench_combined_noise() { eprintln!(); // ---- Sweep p_meas to see how combined noise scales ---- - eprintln!("{:>8} {:>10} {:>10} {:>10} {:>10}", - "p_meas", "H_comb", "SV", "SV_stderr", "H/SV"); + eprintln!( + "{:>8} {:>10} {:>10} {:>10} {:>10}", + "p_meas", "H_comb", "SV", "SV_stderr", "H/SV" + ); for &pm in &[0.0, 0.001, 0.003, 0.005, 0.01, 0.02, 0.05] { - let n = UniformNoise { idle_rz, p1: 0.0, p2: 0.0, p_meas: pm, p_prep: 0.0 }; + let n = UniformNoise { + idle_rz, + p1: 0.0, + p2: 0.0, + p_meas: pm, + p_prep: 0.0, + }; let hp = heisenberg_detection_probability_from_circuit(&gates, &[0, 1], &n, 3, 0.0); let pm_threshold = rng.probability_threshold(pm); @@ -1692,9 +1956,13 @@ fn bench_combined_noise() { out = !out; } os[r] = out; - if r == 0 { sim.pz(&[qid(2)]); } + if r == 0 { + sim.pz(&[qid(2)]); + } + } + if os[0] != os[1] { + d += 1; } - if os[0] != os[1] { d += 1; } } let s = d as f64 / num_shots as f64; let e = (s * (1.0 - s) / num_shots as f64).sqrt(); diff --git a/exp/pecos-eeg/tests/strong_sim_validation.rs b/exp/pecos-eeg/tests/strong_sim_validation.rs index 1cf2edb9e..ed52b050c 100644 --- a/exp/pecos-eeg/tests/strong_sim_validation.rs +++ b/exp/pecos-eeg/tests/strong_sim_validation.rs @@ -28,12 +28,19 @@ fn test_h_correction_matches_exact() { let exact = h.sin().powi(2); // EEG gives h², which ≈ sin²(h) for small h - assert!((p1.total - h * h).abs() < 1e-10, - "h={h}: EEG p(1)={:.6} expected h²={:.6}", p1.total, h * h); + assert!( + (p1.total - h * h).abs() < 1e-10, + "h={h}: EEG p(1)={:.6} expected h²={:.6}", + p1.total, + h * h + ); // Check closeness to exact let rel_err = (p1.total - exact).abs() / exact; - eprintln!("h={h:.2}: EEG={:.6} exact={exact:.6} rel_err={rel_err:.4}", p1.total); + eprintln!( + "h={h:.2}: EEG={:.6} exact={exact:.6} rel_err={rel_err:.4}", + p1.total + ); if h <= 0.1 { assert!(rel_err < 0.02, "h={h}: relative error {rel_err:.4} > 2%"); } @@ -58,8 +65,10 @@ fn test_h_probability_conservation() { let p1 = outcome_probability(&gens, &[true], &stabs); let sum = p0.total + p1.total; - assert!((sum - 1.0).abs() < 0.001, - "p(0)+p(1) = {sum:.6}, expected ≈ 1.0"); + assert!( + (sum - 1.0).abs() < 0.001, + "p(0)+p(1) = {sum:.6}, expected ≈ 1.0" + ); } /// Bell state: H_{Z0} noise should NOT affect Z-basis measurement probabilities. @@ -67,8 +76,8 @@ fn test_h_probability_conservation() { #[test] fn test_bell_h_z_invisible() { let stabs = vec![ - Bm::x(0).multiply(&Bm::x(1)), // XX - Bm::z(0).multiply(&Bm::z(1)), // ZZ + Bm::x(0).multiply(&Bm::x(1)), // XX + Bm::z(0).multiply(&Bm::z(1)), // ZZ ]; let gens = vec![PropagatedEeg { @@ -81,10 +90,18 @@ fn test_bell_h_z_invisible() { // Z₀ has no X component → no bit flips → α(S_Z) = 0 for all outcomes // H correction should be zero for all outcomes - for outcome in &[vec![false, false], vec![true, true], vec![false, true], vec![true, false]] { + for outcome in &[ + vec![false, false], + vec![true, true], + vec![false, true], + vec![true, false], + ] { let p = outcome_probability(&gens, outcome, &stabs); - assert!(p.h_correction.abs() < 1e-10, - "H_Z should be invisible: outcome={outcome:?} h_corr={}", p.h_correction); + assert!( + p.h_correction.abs() < 1e-10, + "H_Z should be invisible: outcome={outcome:?} h_corr={}", + p.h_correction + ); } } @@ -92,8 +109,8 @@ fn test_bell_h_z_invisible() { #[test] fn test_bell_h_x_shifts() { let stabs = vec![ - Bm::x(0).multiply(&Bm::x(1)), // XX - Bm::z(0).multiply(&Bm::z(1)), // ZZ + Bm::x(0).multiply(&Bm::x(1)), // XX + Bm::z(0).multiply(&Bm::z(1)), // ZZ ]; let h = 0.05; @@ -110,8 +127,10 @@ fn test_bell_h_x_shifts() { let p01 = outcome_probability(&gens, &[false, true], &stabs); let p10 = outcome_probability(&gens, &[true, false], &stabs); - eprintln!("Bell + H_X0: p00={:.6} p11={:.6} p01={:.6} p10={:.6}", - p00.total, p11.total, p01.total, p10.total); + eprintln!( + "Bell + H_X0: p00={:.6} p11={:.6} p01={:.6} p10={:.6}", + p00.total, p11.total, p01.total, p10.total + ); // X0 flips qubit 0: maps {00,11} ↔ {10,01} // H_X creates probability at {01,10} from {00,11} @@ -125,12 +144,15 @@ fn test_bell_h_x_shifts() { // Conservation: total ≈ 1 let sum = p00.total + p11.total + p01.total + p10.total; - assert!((sum - 1.0).abs() < 0.01, - "Conservation: sum={sum:.6}"); + assert!((sum - 1.0).abs() < 0.01, "Conservation: sum={sum:.6}"); // Symmetry: p(01) = p(10) (X0 on symmetric Bell state) - assert!((p01.total - p10.total).abs() < 1e-10, - "Symmetry: p01={:.6} p10={:.6}", p01.total, p10.total); + assert!( + (p01.total - p10.total).abs() < 1e-10, + "Symmetry: p01={:.6} p10={:.6}", + p01.total, + p10.total + ); } /// Multiple H generators: verify the off-diagonal Φ correctly accounts @@ -143,8 +165,20 @@ fn test_two_h_generators_interference() { let h2 = 0.03; let gens = vec![ - PropagatedEeg { eeg_type: EegType::H, label: Bm::x(0), label2: None, coeff: h1, source: None }, - PropagatedEeg { eeg_type: EegType::H, label: Bm::y(0), label2: None, coeff: h2, source: None }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::x(0), + label2: None, + coeff: h1, + source: None, + }, + PropagatedEeg { + eeg_type: EegType::H, + label: Bm::y(0), + label2: None, + coeff: h2, + source: None, + }, ]; let p0 = outcome_probability(&gens, &[false], &stabs); @@ -157,11 +191,17 @@ fn test_two_h_generators_interference() { // Diagonal H·H: both contribute +h² to p(1). // Off-diagonal: X·Y = iZ (anticommuting), so C_{X,Y} has α contribution // from the off-diagonal Φ computation. - eprintln!("Two H gens: p0={:.6} p1={:.6} diagonal={diagonal:.6}", p0.total, p1.total); + eprintln!( + "Two H gens: p0={:.6} p1={:.6} diagonal={diagonal:.6}", + p0.total, p1.total + ); // p(1) should be at least the diagonal - assert!(p1.total >= diagonal * 0.9, - "p(1)={:.6} should be ≥ diagonal {diagonal:.6}", p1.total); + assert!( + p1.total >= diagonal * 0.9, + "p(1)={:.6} should be ≥ diagonal {diagonal:.6}", + p1.total + ); // Conservation assert!((p0.total + p1.total - 1.0).abs() < 0.01); @@ -195,7 +235,11 @@ fn test_c_type_alpha() { // p(0) = 1 + (-0.01) = 0.99. eprintln!("C-type: p0={:.6} p1={:.6}", p0.total, p1.total); - assert!((p0.total - 0.99).abs() < 0.02, "p(0) ≈ 0.99: got {:.6}", p0.total); + assert!( + (p0.total - 0.99).abs() < 0.02, + "p(0) ≈ 0.99: got {:.6}", + p0.total + ); assert!(p1.total > 0.0, "p(1) should be positive"); } @@ -220,9 +264,16 @@ fn test_a_type_alpha_zero_for_stabilizer() { // A-type uses Im(Φ). For |0⟩ (real stabilizer state), Φ values // should be real, so Im = 0, giving zero A-type correction. - eprintln!("A-type: p0_corr={:.8} p1_corr={:.8}", p0.s_correction + p0.h_correction, p1.s_correction + p1.h_correction); + eprintln!( + "A-type: p0_corr={:.8} p1_corr={:.8}", + p0.s_correction + p0.h_correction, + p1.s_correction + p1.h_correction + ); // The ca_correction is part of total but not separately exposed. // Just check total is unchanged from noiseless. - assert!((p0.total - 1.0).abs() < 1e-6, "A on |0⟩ should not change p(0)"); + assert!( + (p0.total - 1.0).abs() < 1e-6, + "A on |0⟩ should not change p(0)" + ); assert!(p1.total.abs() < 1e-6, "A on |0⟩ should not change p(1)"); } diff --git a/exp/pecos-eeg/tests/surface_code.rs b/exp/pecos-eeg/tests/surface_code.rs index 3c96a0f37..fd1113127 100644 --- a/exp/pecos-eeg/tests/surface_code.rs +++ b/exp/pecos-eeg/tests/surface_code.rs @@ -6,7 +6,7 @@ use pecos_core::Gate; use pecos_eeg::Bm; -use pecos_eeg::circuit::{analyze_expanded, NoiseModel}; +use pecos_eeg::circuit::{NoiseModel, analyze_expanded}; use pecos_eeg::dem_mapping::*; use pecos_eeg::eeg::EegType; use pecos_eeg::expand; @@ -73,7 +73,9 @@ fn test_repetition_code_coherent_noise() { let noise = NoiseModel::coherent_only(0.1); let result = analyze_expanded(&expanded.gates, &noise); - let h_count = result.generators.iter() + let h_count = result + .generators + .iter() .filter(|g| g.eeg_type == EegType::H) .count(); assert!(h_count > 0, "Should have H generators from RZ noise"); @@ -90,7 +92,11 @@ fn test_repetition_code_coherent_noise() { for entry in &dem_entries { assert!(entry.probability > 0.0, "Probability must be positive"); - assert!(entry.probability < 1.0, "Probability {:.6} too large", entry.probability); + assert!( + entry.probability < 1.0, + "Probability {:.6} too large", + entry.probability + ); } } @@ -101,7 +107,9 @@ fn test_repetition_code_depolarizing_noise() { let noise = NoiseModel::depolarizing(0.003); let result = analyze_expanded(&expanded.gates, &noise); - let s_count = result.generators.iter() + let s_count = result + .generators + .iter() .filter(|g| g.eeg_type == EegType::S) .count(); assert!(s_count > 0); @@ -125,10 +133,16 @@ fn test_repetition_code_combined_noise() { let noise = NoiseModel::depolarizing(0.003).with_idle_rz(0.1); let result = analyze_expanded(&expanded.gates, &noise); - let h_count = result.generators.iter() - .filter(|g| g.eeg_type == EegType::H).count(); - let s_count = result.generators.iter() - .filter(|g| g.eeg_type == EegType::S).count(); + let h_count = result + .generators + .iter() + .filter(|g| g.eeg_type == EegType::H) + .count(); + let s_count = result + .generators + .iter() + .filter(|g| g.eeg_type == EegType::S) + .count(); assert!(h_count > 0); assert!(s_count > 0); @@ -159,8 +173,11 @@ fn test_eeg_generator_count_scales_linearly() { let noise = NoiseModel::coherent_only(0.1); let result = analyze_expanded(&expanded.gates, &noise); - let h_count = result.generators.iter() - .filter(|g| g.eeg_type == EegType::H).count(); + let h_count = result + .generators + .iter() + .filter(|g| g.eeg_type == EegType::H) + .count(); eprintln!("Rounds={num_rounds}: {h_count} H generators"); assert!(h_count < 1000, "Generator count should be polynomial"); } diff --git a/exp/pecos-neo/src/command/builder.rs b/exp/pecos-neo/src/command/builder.rs index 65b673d87..aafe37175 100644 --- a/exp/pecos-neo/src/command/builder.rs +++ b/exp/pecos-neo/src/command/builder.rs @@ -373,7 +373,7 @@ impl CommandBuilder { self } - /// Add SXXdg gates. + /// Add `SXXdg` gates. #[must_use] pub fn sxxdg( mut self, @@ -400,7 +400,7 @@ impl CommandBuilder { self } - /// Add SYYdg gates. + /// Add `SYYdg` gates. #[must_use] pub fn syydg( mut self, @@ -415,7 +415,7 @@ impl CommandBuilder { self } - /// Add SZZdg gates (inverse of SZZ). + /// Add `SZZdg` gates (inverse of `SZZ`). #[must_use] pub fn szzdg( mut self, diff --git a/exp/pecos-neo/src/tool.rs b/exp/pecos-neo/src/tool.rs index 26002d83a..6803f8937 100644 --- a/exp/pecos-neo/src/tool.rs +++ b/exp/pecos-neo/src/tool.rs @@ -96,8 +96,8 @@ pub use importance::{ pub use plugin::{Plugin, PluginGroup}; pub use resource::{Resource, Resources}; pub use simulation::{ - Circuit, CustomBackendBuilder, ImportanceSamplingBuilder, NoiseResource, Sampling, - QuantumBackend, SimConfig, SimNeoBuilder, SimNeoInput, Simulation, SimulationResults, + Circuit, CustomBackendBuilder, ImportanceSamplingBuilder, NoiseResource, QuantumBackend, + Sampling, SimConfig, SimNeoBuilder, SimNeoInput, Simulation, SimulationResults, SimulatorFactory, SparseStabBuilder, StateVecBuilder, StoredOverrides, custom_backend, custom_backend_from_factory, custom_backend_with_rotations, importance_sampling, sim_neo, sim_neo_builder, sparse_stab, state_vector, diff --git a/exp/pecos-neo/src/tool/simulation.rs b/exp/pecos-neo/src/tool/simulation.rs index 59fed84af..d218dc1cd 100644 --- a/exp/pecos-neo/src/tool/simulation.rs +++ b/exp/pecos-neo/src/tool/simulation.rs @@ -844,7 +844,6 @@ pub enum Sampling { /// Configuration for importance sampling. config: ImportanceSamplingBuilder, }, - } impl Default for Sampling { @@ -866,7 +865,6 @@ impl Sampling { let workers = std::thread::available_parallelism().map_or(1, std::num::NonZero::get); Self::MonteCarlo { workers } } - } /// Accumulated simulation results. @@ -2547,7 +2545,6 @@ fn is_sim_post_shot(resources: &mut Resources) { resources.get_mut::().shot_index += 1; } - // --- Simulation Handle --- /// Reusable simulation handle. diff --git a/python/pecos-rslib-exp/src/eeg_bindings.rs b/python/pecos-rslib-exp/src/eeg_bindings.rs index f40eaca7a..3685b8ca1 100644 --- a/python/pecos-rslib-exp/src/eeg_bindings.rs +++ b/python/pecos-rslib-exp/src/eeg_bindings.rs @@ -5,11 +5,19 @@ //! Python bindings for EEG DEM builder. use pecos_core::pauli::pauli_bitmask::BitmaskStorage; -use pecos_core::{Angle64, Gate, GateAngles, GateMeasIds, GateParams, GateQubits, QubitId}; +use pecos_core::{Angle64, Gate, GateAngles, GateMeasIds, GateParams, QubitId}; use pecos_eeg::Bm; use pecos_eeg::circuit::{self, NoiseModel}; +use pecos_eeg::correlation_table::CorrelationTableInput; use pecos_eeg::dem_mapping::{DemEntry, Detector, Observable}; +use pecos_eeg::noise_characterization::NoiseCharacterizationInput; use pyo3::prelude::*; +use rayon::iter::{IntoParallelRefIterator, ParallelIterator}; +use std::collections::BTreeMap; + +type PyDemEvent = (f64, Vec, Vec); +type PyEegEventDiagnostic = (Vec, usize, usize, Vec, f64); +type MeasurementRecordDefinition = (usize, Vec, Vec); /// Build a DEM using forward EEG analysis (perturbative, fast). /// @@ -60,7 +68,7 @@ pub fn perturbative_dem_events( p_prep: f64, h_formula: &str, bch_order: u32, -) -> PyResult, Vec)>> { +) -> PyResult> { let entries = run_eeg( tick_circuit, idle_rz, @@ -131,7 +139,7 @@ pub fn eeg_event_diagnostics( p2: f64, p_meas: f64, p_prep: f64, -) -> PyResult, usize, usize, Vec, f64)>> { +) -> PyResult> { let noise = NoiseModel { idle_rz, p1, @@ -144,14 +152,11 @@ pub fn eeg_event_diagnostics( let result = circuit::analyze_expanded(&expanded.gates, &noise); let (detectors, _observables) = extract_detectors_expanded(tick_circuit, &expanded)?; - use pecos_eeg::eeg::EegType; - use std::collections::BTreeMap; - // Group H generators by DEM event, tracking labels let mut h_events: BTreeMap, BTreeMap> = BTreeMap::new(); for g in &result.generators { - if g.eeg_type != EegType::H { + if g.eeg_type != pecos_eeg::eeg::EegType::H { continue; } // Classify manually @@ -267,19 +272,16 @@ pub fn eeg_per_detector( }; // H contribution: quadratic form with beta - let n = det_h.len(); let h_prob = match formula { pecos_eeg::dem_mapping::HFormula::Taylor | pecos_eeg::dem_mapping::HFormula::SinSquared | pecos_eeg::dem_mapping::HFormula::ExactSubset => { let mut total = 0.0_f64; - for j in 0..n { - let (idx_j, h_j) = det_h[j]; + for (j, &(idx_j, h_j)) in det_h.iter().enumerate() { // Diagonal total += h_j * h_j; // Off-diagonal with beta - for k in (j + 1)..n { - let (idx_k, h_k) = det_h[k]; + for &(idx_k, h_k) in det_h.iter().skip(j + 1) { let q_j = &h_labels[idx_j].0; let q_k = &h_labels[idx_k].0; @@ -429,7 +431,6 @@ pub fn exact_detection_rates( // Parallelize across detectors — each walk is independent. // Uses sparse traversal (heap + gate index) for O(active_gates) instead of O(all_gates). - use rayon::prelude::*; let results: Vec<(usize, f64)> = detectors .par_iter() .map(|det| { @@ -513,7 +514,6 @@ pub fn exact_pairwise_rates( let marginals: Vec = detectors.iter().map(|d| walk(&d.stabilizer)).collect(); // Pairwise: P(Di AND Dj) = (P(Di) + P(Dj) - P_walk(Si*Sj)) / 2 - use rayon::prelude::*; let pairs: Vec<(usize, usize)> = (0..detectors.len()) .flat_map(|i| ((i + 1)..detectors.len()).map(move |j| (i, j))) .collect(); @@ -758,7 +758,7 @@ pub fn exact_correlation_table( }; let gates = extract_gates(tick_circuit)?; let expanded = pecos_eeg::expand::expand_circuit(&gates); - let (detectors, _observables) = extract_detectors_expanded(tick_circuit, &expanded)?; + let (detectors, observables) = extract_detectors_expanded(tick_circuit, &expanded)?; let init_gates: Vec = (0..expanded.num_original_qubits) .map(|q| pecos_eeg::expand::make_gate(pecos_core::gate_type::GateType::PZ, &[q])) @@ -766,16 +766,16 @@ pub fn exact_correlation_table( let stab = pecos_eeg::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); - let table = pecos_eeg::correlation_table::compute_correlation_table( - &expanded.gates, - &noise, - &detectors, - &_observables, - &stab, - expanded.num_qubits, + let table = pecos_eeg::correlation_table::compute_correlation_table(CorrelationTableInput { + gates: &expanded.gates, + noise: &noise, + detectors: &detectors, + observables: &observables, + initial_stab: &stab, + num_qubits: expanded.num_qubits, max_order, - prune, - ); + prune_threshold: prune, + }); // String labels: "D0", "D1", "L0" — consistent with Stim DEM format. let mut result: Vec<(Vec, f64)> = table @@ -830,16 +830,16 @@ pub fn correlation_matching_dem( let stab = pecos_eeg::stabilizer::StabilizerGroup::from_circuit(&init_gates, expanded.num_qubits); - let table = pecos_eeg::correlation_table::compute_correlation_table( - &expanded.gates, - &noise, - &detectors, - &observables, - &stab, - expanded.num_qubits, + let table = pecos_eeg::correlation_table::compute_correlation_table(CorrelationTableInput { + gates: &expanded.gates, + noise: &noise, + detectors: &detectors, + observables: &observables, + initial_stab: &stab, + num_qubits: expanded.num_qubits, max_order, - prune, - ); + prune_threshold: prune, + }); Ok(table.to_matching_dem()) } @@ -942,17 +942,19 @@ pub fn noise_characterization( let obs_meas_ids = extract_meas_id_defs(tick_circuit, "observables")?; let nc = pecos_eeg::noise_characterization::NoiseCharacterization::build( - &expanded.gates, - &base_noise, - structure_noise.as_deref(), - &detectors, - &observables, - &stab, - expanded.num_qubits, - max_order, - prune, - &det_meas_ids, - &obs_meas_ids, + NoiseCharacterizationInput { + gates: &expanded.gates, + noise: &base_noise, + structure_noise: structure_noise.as_deref(), + detectors: &detectors, + observables: &observables, + initial_stab: &stab, + num_qubits: expanded.num_qubits, + max_order, + prune_threshold: prune, + detector_meas_ids: &det_meas_ids, + observable_meas_ids: &obs_meas_ids, + }, ); Ok(( @@ -962,8 +964,6 @@ pub fn noise_characterization( )) } -/// Build a coherent DEM via backward mechanism extraction. -/// // -- Internal -- fn parse_h_formula(s: &str) -> PyResult { @@ -1137,7 +1137,7 @@ fn extract_gates(py_tc: &Bound<'_, PyAny>) -> PyResult> { if pair.len() == 2 { tick_gates.push(Gate { gate_type: gt, - qubits: GateQubits::from_iter(pair.iter().map(|&q| QubitId(q))), + qubits: pair.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: GateMeasIds::new(), @@ -1165,7 +1165,7 @@ fn extract_gates(py_tc: &Bound<'_, PyAny>) -> PyResult> { for &q in &qubits { tick_gates.push(Gate { gate_type: gt, - qubits: GateQubits::from_iter(std::iter::once(QubitId(q))), + qubits: std::iter::once(QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: GateMeasIds::new(), @@ -1177,7 +1177,7 @@ fn extract_gates(py_tc: &Bound<'_, PyAny>) -> PyResult> { for &q in &qubits { tick_gates.push(Gate { gate_type: pecos_core::gate_type::GateType::PZ, - qubits: GateQubits::from_iter(std::iter::once(QubitId(q))), + qubits: std::iter::once(QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: GateMeasIds::new(), @@ -1198,17 +1198,16 @@ fn extract_gates(py_tc: &Bound<'_, PyAny>) -> PyResult> { }; let mut g = Gate { gate_type: gt, - qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + qubits: qubits.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: GateMeasIds::new(), }; - if gt == pecos_core::gate_type::GateType::RZ { - if let Ok(angles) = gate.getattr("angles")?.extract::>() { - if let Some(&a) = angles.first() { - g.angles.push(Angle64::from_radians(a)); - } - } + if gt == pecos_core::gate_type::GateType::RZ + && let Ok(angles) = gate.getattr("angles")?.extract::>() + && let Some(&a) = angles.first() + { + g.angles.push(Angle64::from_radians(a)); } tick_gates.push(g); } @@ -1224,6 +1223,17 @@ fn extract_gates(py_tc: &Bound<'_, PyAny>) -> PyResult> { Ok(gates) } +fn measurement_record_index(record: i32, num_measurements: usize) -> Option { + let idx = if record < 0 { + i32::try_from(num_measurements).ok()?.checked_add(record)? + } else { + record + }; + usize::try_from(idx) + .ok() + .filter(|&idx| idx < num_measurements) +} + fn extract_detectors_expanded( py_tc: &Bound<'_, PyAny>, expanded: &pecos_eeg::expand::ExpandedCircuit, @@ -1239,41 +1249,37 @@ fn extract_detectors_expanded( let mut observables = Vec::new(); // Parse detector JSON from metadata - if let Ok(det_json_str) = py_tc.call_method1("get_meta", ("detectors",)) { - if let Ok(det_json) = det_json_str.extract::() { - if let Ok(det_list) = serde_json_parse_detectors(&det_json) { - for (id, records) in det_list { - let mut bm = Bm::default(); - for &rec in &records { - let abs_idx = if rec < 0 { num_meas as i32 + rec } else { rec }; - if abs_idx >= 0 && (abs_idx as usize) < num_meas { - // Map to AUXILIARY qubit in expanded circuit - let aux_qubit = expanded.measurement_qubit[abs_idx as usize]; - bm.z_bits.xor_bit(aux_qubit); - } - } - detectors.push(Detector { id, stabilizer: bm }); + if let Ok(det_json_str) = py_tc.call_method1("get_meta", ("detectors",)) + && let Ok(det_json) = det_json_str.extract::() + && let Ok(det_list) = serde_json_parse_detectors(&det_json) + { + for (id, records) in det_list { + let mut bm = Bm::default(); + for &rec in &records { + if let Some(abs_idx) = measurement_record_index(rec, num_meas) { + // Map to AUXILIARY qubit in expanded circuit + let aux_qubit = expanded.measurement_qubit[abs_idx]; + bm.z_bits.xor_bit(aux_qubit); } } + detectors.push(Detector { id, stabilizer: bm }); } } // Parse observable JSON from metadata - if let Ok(obs_json_str) = py_tc.call_method1("get_meta", ("observables",)) { - if let Ok(obs_json) = obs_json_str.extract::() { - if let Ok(obs_list) = serde_json_parseobservables(&obs_json) { - for (id, records) in obs_list { - let mut bm = Bm::default(); - for &rec in &records { - let abs_idx = if rec < 0 { num_meas as i32 + rec } else { rec }; - if abs_idx >= 0 && (abs_idx as usize) < num_meas { - let aux_qubit = expanded.measurement_qubit[abs_idx as usize]; - bm.z_bits.xor_bit(aux_qubit); - } - } - observables.push(Observable { id, pauli: bm }); + if let Ok(obs_json_str) = py_tc.call_method1("get_meta", ("observables",)) + && let Ok(obs_json) = obs_json_str.extract::() + && let Ok(obs_list) = serde_json_parseobservables(&obs_json) + { + for (id, records) in obs_list { + let mut bm = Bm::default(); + for &rec in &records { + if let Some(abs_idx) = measurement_record_index(rec, num_meas) { + let aux_qubit = expanded.measurement_qubit[abs_idx]; + bm.z_bits.xor_bit(aux_qubit); } } + observables.push(Observable { id, pauli: bm }); } } @@ -1286,15 +1292,17 @@ fn serde_json_parse_detectors(json: &str) -> Result)>, Stri // Simple approach: find "id" and "records" fields via string scanning let mut result = Vec::new(); let mut pos = 0; - while let Some(start) = json[pos..].find("{") { + while let Some(start) = json[pos..].find('{') { let start = pos + start; let end = json[start..] - .find("}") + .find('}') .map(|e| start + e + 1) .ok_or_else(|| "Unmatched brace".to_string())?; let entry = &json[start..end]; - let id = extract_json_int(entry, "\"id\"").unwrap_or(result.len() as i64) as usize; + let id = extract_json_int(entry, "\"id\"") + .and_then(|value| usize::try_from(value).ok()) + .unwrap_or(result.len()); let records = extract_json_int_array(entry, "\"records\"").unwrap_or_default(); result.push((id, records)); @@ -1311,15 +1319,15 @@ fn serde_json_parseobservables(json: &str) -> Result)>, Str fn extract_meas_id_defs( py_tc: &Bound<'_, pyo3::PyAny>, key: &str, // "detectors" or "observables" -) -> PyResult, Vec)>> { +) -> PyResult> { let mut result = Vec::new(); - if let Ok(json_str) = py_tc.call_method1("get_meta", (key,)) { - if let Ok(s) = json_str.extract::() { - // Parse JSON: each item has id, meas_ids (optional), records - let items = parse_json_items(&s); - for (idx, (records, meas_ids)) in items.iter().enumerate() { - result.push((idx, meas_ids.clone(), records.clone())); - } + if let Ok(json_str) = py_tc.call_method1("get_meta", (key,)) + && let Ok(s) = json_str.extract::() + { + // Parse JSON: each item has id, meas_ids (optional), records + let items = parse_json_items(&s); + for (idx, (records, meas_ids)) in items.iter().enumerate() { + result.push((idx, meas_ids.clone(), records.clone())); } } Ok(result) @@ -1347,15 +1355,19 @@ fn parse_json_items(json: &str) -> Vec<(Vec, Vec)> { } '}' => { depth -= 1; - if depth == 1 { - if let Some(start) = block_start { - let block = &trimmed[start..=i]; - let records = extract_json_int_array(block, "records").unwrap_or_default(); - let meas_ids = extract_json_int_array(block, "meas_ids") - .map(|v| v.into_iter().map(|x| x as usize).collect()) - .unwrap_or_default(); - result.push((records, meas_ids)); - } + if depth == 1 + && let Some(start) = block_start + { + let block = &trimmed[start..=i]; + let records = extract_json_int_array(block, "records").unwrap_or_default(); + let meas_ids = extract_json_int_array(block, "meas_ids") + .map(|v| { + v.into_iter() + .filter_map(|x| usize::try_from(x).ok()) + .collect() + }) + .unwrap_or_default(); + result.push((records, meas_ids)); } } '[' if depth == 0 => { diff --git a/python/pecos-rslib-exp/src/lib.rs b/python/pecos-rslib-exp/src/lib.rs index da803d18b..c2f2a4ed2 100644 --- a/python/pecos-rslib-exp/src/lib.rs +++ b/python/pecos-rslib-exp/src/lib.rs @@ -10,6 +10,20 @@ // express or implied. See the License for the specific language governing permissions and // limitations under the License. +// Experimental PyO3 binding signatures are constrained by Python-callable APIs +// and generated method wrappers. Python docstrings also contain Python snippets +// that Clippy's Rust-doc Markdown lint misclassifies. Keep this list limited to +// binding/docs shape lints. +#![allow( + clippy::doc_markdown, + clippy::missing_errors_doc, + clippy::missing_panics_doc, + clippy::needless_pass_by_value, + clippy::too_many_arguments, + clippy::unnecessary_wraps, + clippy::unused_self +)] + //! Python bindings for experimental PECOS simulators. //! //! Exposes `StabMps` (stabilizer + MPS hybrid) and `Mast` (magic state diff --git a/python/pecos-rslib-exp/src/sim_neo_bindings.rs b/python/pecos-rslib-exp/src/sim_neo_bindings.rs index cb1ee8752..62b1c3148 100644 --- a/python/pecos-rslib-exp/src/sim_neo_bindings.rs +++ b/python/pecos-rslib-exp/src/sim_neo_bindings.rs @@ -32,6 +32,22 @@ use pecos_neo::tool::sim_neo; use pecos_simulators::measurement_sampler::SampleResult; use pyo3::prelude::*; +#[derive(serde::Deserialize)] +struct RecDef { + records: Vec, +} + +fn measurement_record_index(record: i32, num_measurements: usize) -> Option { + let idx = if record < 0 { + i32::try_from(num_measurements).ok()?.checked_add(record)? + } else { + record + }; + usize::try_from(idx) + .ok() + .filter(|&idx| idx < num_measurements) +} + // ============================================================================ // Columnar raw measurement result (stays in Rust memory) // ============================================================================ @@ -104,7 +120,9 @@ impl PyRawMeasurementResult { "negative {name} index {idx}" ))); } - let u = idx as usize; + let u = usize::try_from(idx).map_err(|_| { + pyo3::exceptions::PyIndexError::new_err(format!("invalid {name} index {idx}")) + })?; if u >= len { return Err(pyo3::exceptions::PyIndexError::new_err(format!( "{name} {u} out of range ({len})" @@ -122,7 +140,7 @@ impl PyRawMeasurementResult { /// Construct from row-major data (stabilizer/statevec path). pub fn from_rows(rows: Vec>) -> Self { - let num_measurements = rows.first().map_or(0, |r| r.len()); + let num_measurements = rows.first().map_or(0, Vec::len); Self { storage: RawMeasurementStorage::RowMajor { rows, @@ -736,11 +754,6 @@ impl PySimNeoBuilder { }) .unwrap_or_else(|| "[]".to_string()); - #[derive(serde::Deserialize)] - struct RecDef { - records: Vec, - } - let det_records: Vec> = serde_json::from_str::>(&det_json) .map(|defs| defs.iter().map(|d| d.records.clone()).collect()) .unwrap_or_default(); @@ -779,12 +792,12 @@ impl PySimNeoBuilder { /// Convert CommandQueue to Vec for EEG analysis. fn commands_to_gates(commands: &pecos_neo::command::CommandQueue) -> Vec { - use pecos_core::{Gate, GateAngles, GateMeasIds, GateParams, GateQubits}; + use pecos_core::{Gate, GateAngles, GateMeasIds, GateParams}; commands .iter() .map(|cmd| { - let qubits = GateQubits::from_iter(cmd.qubits.iter().copied()); + let qubits = cmd.qubits.iter().copied().collect(); let mut angles = GateAngles::new(); for &a in &cmd.angles { angles.push(a); @@ -844,11 +857,11 @@ fn build_rust_tick_circuit(py_tc: &Bound<'_, PyAny>) -> PyResult>() { - // Deserialize — but TickCircuit doesn't impl serde. Skip. - let _ = bytes; - } + if let Ok(tc_bytes) = py_tc.call_method0("_serialize_inner") + && let Ok(bytes) = tc_bytes.extract::>() + { + // Deserialize — but TickCircuit doesn't impl serde. Skip. + let _ = bytes; } // The only reliable fast path: call `to_dag_circuit()` on the Python TC, @@ -887,10 +900,10 @@ fn build_rust_tick_circuit_from_gates( for gate in &gates { let gate_type_obj = gate.getattr("gate_type")?; - let gate_name: String = format!("{:?}", gate_type_obj); + let gate_name: String = format!("{gate_type_obj:?}"); let gate_name = gate_name .split('.') - .last() + .next_back() .unwrap_or(&gate_name) .to_string(); let py_qubits = gate.getattr("qubits")?; @@ -937,23 +950,23 @@ fn build_rust_tick_circuit_from_gates( } // Copy metadata from Python TickCircuit - if let Ok(num_meas) = py_tc.call_method1("get_meta", ("num_measurements",)) { - if let Ok(s) = num_meas.extract::() { - tc.set_meta("num_measurements", Attribute::String(s)); - } + if let Ok(num_meas) = py_tc.call_method1("get_meta", ("num_measurements",)) + && let Ok(s) = num_meas.extract::() + { + tc.set_meta("num_measurements", Attribute::String(s)); } - if let Ok(det_json) = py_tc.call_method1("get_meta", ("detectors",)) { - if let Ok(s) = det_json.extract::() { - // Create structured annotations from JSON - create_annotations_from_json(&mut tc, &s, &all_meas_refs, true); - tc.set_meta("detectors", Attribute::String(s)); - } + if let Ok(det_json) = py_tc.call_method1("get_meta", ("detectors",)) + && let Ok(s) = det_json.extract::() + { + // Create structured annotations from JSON + create_annotations_from_json(&mut tc, &s, &all_meas_refs, true); + tc.set_meta("detectors", Attribute::String(s)); } - if let Ok(obs_json) = py_tc.call_method1("get_meta", ("observables",)) { - if let Ok(s) = obs_json.extract::() { - create_annotations_from_json(&mut tc, &s, &all_meas_refs, false); - tc.set_meta("observables", Attribute::String(s)); - } + if let Ok(obs_json) = py_tc.call_method1("get_meta", ("observables",)) + && let Ok(s) = obs_json.extract::() + { + create_annotations_from_json(&mut tc, &s, &all_meas_refs, false); + tc.set_meta("observables", Attribute::String(s)); } copy_operator_annotations_from_python(py_tc, &mut tc)?; @@ -1035,11 +1048,6 @@ fn create_annotations_from_json( all_meas_refs: &[pecos_quantum::TickMeasRef], is_detector: bool, ) { - #[derive(serde::Deserialize)] - struct RecDef { - records: Vec, - } - let num_meas = all_meas_refs.len(); if let Ok(defs) = serde_json::from_str::>(json_str) { for def in &defs { @@ -1047,7 +1055,7 @@ fn create_annotations_from_json( .records .iter() .filter_map(|&rec| { - let abs_idx = (num_meas as i32 + rec) as usize; + let abs_idx = measurement_record_index(rec, num_meas)?; all_meas_refs.get(abs_idx).copied() }) .collect(); @@ -1069,7 +1077,7 @@ fn build_gate_from_python( qubit_ids: &[pecos_core::QubitId], ) -> PyResult { use pecos_core::gate_type::GateType; - use pecos_core::{Gate, GateAngles, GateMeasIds, GateParams, GateQubits}; + use pecos_core::{Gate, GateAngles, GateMeasIds, GateParams}; let gate_type = match gate_name { "H" => GateType::H, @@ -1112,22 +1120,22 @@ fn build_gate_from_python( }; let mut angles = GateAngles::new(); - if let Ok(py_angle) = gate.getattr("angle") { - if let Ok(a) = py_angle.extract::() { - angles.push(pecos_core::Angle64::from_radians(a)); - } + if let Ok(py_angle) = gate.getattr("angle") + && let Ok(a) = py_angle.extract::() + { + angles.push(pecos_core::Angle64::from_radians(a)); } - if let Ok(py_angles) = gate.getattr("angles") { - if let Ok(a_list) = py_angles.extract::>() { - for a in a_list { - angles.push(pecos_core::Angle64::from_radians(a)); - } + if let Ok(py_angles) = gate.getattr("angles") + && let Ok(a_list) = py_angles.extract::>() + { + for a in a_list { + angles.push(pecos_core::Angle64::from_radians(a)); } } Ok(Gate { gate_type, - qubits: GateQubits::from_iter(qubit_ids.iter().copied()), + qubits: qubit_ids.iter().copied().collect(), angles, params: GateParams::new(), meas_ids: GateMeasIds::new(), @@ -1309,10 +1317,9 @@ fn extract_commands(py_tc: &Bound<'_, PyAny>) -> PyResult { return Err(PyErr::new::(format!( - "Unsupported gate type '{}' in extract_commands. \ + "Unsupported gate type '{name}' in extract_commands. \ Add support in sim_neo_bindings.rs or lower to supported gates \ - with tc.lower_clifford_rotations().", - name + with tc.lower_clifford_rotations()." ))); } } @@ -1496,14 +1503,19 @@ impl PyFaultCatalog { } fn __getitem__(&self, py: Python<'_>, index: isize) -> PyResult> { - let len = self.locations.len() as isize; + let len = isize::try_from(self.locations.len()).map_err(|_| { + pyo3::exceptions::PyIndexError::new_err("fault catalog is too large to index") + })?; let index = if index < 0 { len + index } else { index }; if index < 0 || index >= len { return Err(pyo3::exceptions::PyIndexError::new_err( "fault catalog index out of range", )); } - Ok(self.locations[index as usize].clone_ref(py)) + let index = usize::try_from(index).map_err(|_| { + pyo3::exceptions::PyIndexError::new_err("fault catalog index out of range") + })?; + Ok(self.locations[index].clone_ref(py)) } fn __iter__(slf: PyRef<'_, Self>, py: Python<'_>) -> PyResult> { diff --git a/python/pecos-rslib/src/fault_tolerance_bindings.rs b/python/pecos-rslib/src/fault_tolerance_bindings.rs index a017967b3..32821568d 100644 --- a/python/pecos-rslib/src/fault_tolerance_bindings.rs +++ b/python/pecos-rslib/src/fault_tolerance_bindings.rs @@ -67,6 +67,23 @@ use pecos_quantum::QubitId; use pyo3::Py; use pyo3::prelude::*; +type PyDemMechanismTuple = (f64, Vec, Vec); +type PyDemFitResult = (Vec, Vec); + +// Adapter for decoder factories that require `Send + Sync` trait objects. +// Decoder implementations own their state; Python access remains GIL-mediated. +struct SendWrapper(Box); +unsafe impl Send for SendWrapper {} +unsafe impl Sync for SendWrapper {} +impl pecos_decoders::ObservableDecoder for SendWrapper { + fn decode_to_observables( + &mut self, + syndrome: &[u8], + ) -> Result { + self.0.decode_to_observables(syndrome) + } +} + // ============================================================================= // Fault Location Types // ============================================================================= @@ -537,7 +554,7 @@ impl PyDagFaultAnalyzer { /// dag = DagCircuit() /// # ... build circuit ... /// -/// # Build influence map with tracked operator probes +/// # Build influence map with tracked Pauli operators /// builder = InfluenceBuilder(dag) /// builder.with_tracked_z([0, 1, 2]) # Track a Z string on these qubits /// influence_map = builder.build() @@ -2595,7 +2612,7 @@ impl PySampleBatch { /// Build from row-major data (from Python constructor). fn from_row_major(detection_events: Vec>, observable_masks: Vec) -> Self { let num_shots = detection_events.len(); - let num_detectors = detection_events.first().map_or(0, |r| r.len()); + let num_detectors = detection_events.first().map_or(0, Vec::len); let num_words = num_shots.div_ceil(64); // Convert row-major → columnar @@ -2620,9 +2637,9 @@ impl PySampleBatch { for (shot, &mask) in observable_masks.iter().enumerate() { let word_idx = shot / 64; let bit_mask = 1u64 << (shot % 64); - for obs_idx in 0..max_obs { + for (obs_idx, obs_column) in obs_columns.iter_mut().enumerate().take(max_obs) { if mask & (1u64 << obs_idx) != 0 { - obs_columns[obs_idx][word_idx] |= bit_mask; + obs_column[word_idx] |= bit_mask; } } } @@ -2653,7 +2670,7 @@ impl PySampleBatch { observable_masks.len(), ))); } - let expected_len = detection_events.first().map_or(0, |r| r.len()); + let expected_len = detection_events.first().map_or(0, Vec::len); for (i, row) in detection_events.iter().enumerate() { if row.len() != expected_len { return Err(pyo3::exceptions::PyValueError::new_err(format!( @@ -2806,9 +2823,7 @@ impl PySampleBatch { // Pad or truncate to decoder's num_detectors let take = syndrome.len().min(num_detectors); flat.extend_from_slice(&syndrome[..take]); - for _ in take..num_detectors { - flat.push(0); - } + flat.extend(std::iter::repeat_n(0, num_detectors - take)); } let config = BatchConfig { @@ -3111,13 +3126,13 @@ impl PyDemSampler { if let Ok(dag) = circuit.extract::>() { - let inner = RustNewDemSampler::from_circuit(&dag.inner, noise) + let inner = RustNewDemSampler::from_circuit(&dag.inner, &noise) .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))?; Ok(Self { inner }) } else if let Ok(tc) = circuit.extract::>() { - let inner = RustNewDemSampler::from_tick_circuit(&tc.inner, noise) + let inner = RustNewDemSampler::from_tick_circuit(&tc.inner, &noise) .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))?; Ok(Self { inner }) } else { @@ -3153,38 +3168,36 @@ impl PyDemSampler { } // Parse: error(prob) D0 D3 L0 - if let Some(rest) = line.strip_prefix("error(") { - if let Some(paren_end) = rest.find(')') { - let prob: f64 = rest[..paren_end].parse().map_err(|e| { - pyo3::exceptions::PyValueError::new_err(format!("bad probability: {e}")) + let Some(rest) = line.strip_prefix("error(") else { + continue; + }; + let Some(paren_end) = rest.find(')') else { + continue; + }; + let prob: f64 = rest[..paren_end].parse().map_err(|e| { + pyo3::exceptions::PyValueError::new_err(format!("bad probability: {e}")) + })?; + let tokens = rest[paren_end + 1..].split_whitespace(); + let mut dets = Vec::new(); + let mut obs = Vec::new(); + for tok in tokens { + if let Some(d) = tok.strip_prefix('D') { + let id: u32 = d.parse().map_err(|e| { + pyo3::exceptions::PyValueError::new_err(format!("bad detector: {e}")) })?; - let tokens = rest[paren_end + 1..].split_whitespace(); - let mut dets = Vec::new(); - let mut obs = Vec::new(); - for tok in tokens { - if let Some(d) = tok.strip_prefix('D') { - let id: u32 = d.parse().map_err(|e| { - pyo3::exceptions::PyValueError::new_err(format!( - "bad detector: {e}" - )) - })?; - dets.push(id); - max_det = max_det.max(id + 1); - } else if let Some(l) = tok.strip_prefix('L') { - let id: u32 = l.parse().map_err(|e| { - pyo3::exceptions::PyValueError::new_err(format!( - "bad observable: {e}" - )) - })?; - obs.push(id); - max_obs = max_obs.max(id + 1); - } - } - if prob > 0.0 { - mechanisms.push((prob, dets, obs)); - } + dets.push(id); + max_det = max_det.max(id + 1); + } else if let Some(l) = tok.strip_prefix('L') { + let id: u32 = l.parse().map_err(|e| { + pyo3::exceptions::PyValueError::new_err(format!("bad observable: {e}")) + })?; + obs.push(id); + max_obs = max_obs.max(id + 1); } } + if prob > 0.0 { + mechanisms.push((prob, dets, obs)); + } } let engine = @@ -3421,7 +3434,9 @@ impl PyDemSampler { .filter_map(|&idx| stats.dem_output_counts().get(idx).copied()) .collect(); let logical_rates = stats.logical_rates(&observable_indices); + #[allow(clippy::cast_precision_loss)] // Counts are converted to rates for Python reporting. let n = stats.total_shots as f64; + #[allow(clippy::cast_precision_loss)] // Counts are converted to rates for Python reporting. let tracked_op_rates: Vec = per_tracked_op .iter() .map(|&count| count as f64 / n) @@ -3928,7 +3943,7 @@ impl PyParsedDem { fn to_string_decomposed(&self) -> PyResult { self.inner .to_string_decomposed() - .map_err(|e| pyo3::exceptions::PyValueError::new_err(e)) + .map_err(pyo3::exceptions::PyValueError::new_err) } /// Aggregate mechanisms by their effect. @@ -4364,21 +4379,6 @@ impl PyObservableSubgraphDecoder { }); } - // Wrapper to make any ObservableDecoder Send. - // All our decoder implementations own their data (no Rc/RefCell), - // so this is safe. The GIL prevents concurrent Python access. - struct SendWrapper(Box); - unsafe impl Send for SendWrapper {} - unsafe impl Sync for SendWrapper {} - impl pecos_decoders::ObservableDecoder for SendWrapper { - fn decode_to_observables( - &mut self, - syndrome: &[u8], - ) -> Result { - self.0.decode_to_observables(syndrome) - } - } - let inner = ObservableSubgraphDecoder::from_dem_windowed( dem, &rust_stab_coords, @@ -4507,18 +4507,6 @@ impl PyObservableSubgraphDecoder { .build() .map_err(|e| PyErr::new::(e.to_string()))?; - struct SendWrapper(Box); - unsafe impl Send for SendWrapper {} - unsafe impl Sync for SendWrapper {} - impl pecos_decoders::ObservableDecoder for SendWrapper { - fn decode_to_observables( - &mut self, - syn: &[u8], - ) -> Result { - self.0.decode_to_observables(syn) - } - } - let errors: usize = pool.install(|| { // Split into chunks, each chunk gets its own decoder + batch decode let chunk_size = n.div_ceil(rayon::current_num_threads()); @@ -4685,18 +4673,6 @@ impl PyWindowedOsdDecoder { let config = WindowedOsdConfig { step, buffer }; - struct SendWrapper(Box); - unsafe impl Send for SendWrapper {} - unsafe impl Sync for SendWrapper {} - impl pecos_decoders::ObservableDecoder for SendWrapper { - fn decode_to_observables( - &mut self, - syndrome: &[u8], - ) -> Result { - self.0.decode_to_observables(syndrome) - } - } - let inner = WindowedOsdDecoder::from_dem(dem, &sc, &config, |subgraph| { let sub_dem = subgraph_to_dem_string(subgraph); let d = create_observable_decoder(&sub_dem, inner_decoder) @@ -4813,18 +4789,6 @@ impl PyLogicalAlgorithmDecoder { }); } - struct SendWrapper(Box); - unsafe impl Send for SendWrapper {} - unsafe impl Sync for SendWrapper {} - impl pecos_decoders::ObservableDecoder for SendWrapper { - fn decode_to_observables( - &mut self, - syn: &[u8], - ) -> Result { - self.0.decode_to_observables(syn) - } - } - let inner_str = inner_decoder.to_string(); // Build full-circuit OSD from the full DEM @@ -4913,9 +4877,8 @@ impl PyLogicalAlgorithmDecoder { num_observables: num_obs, }; - use pecos_decoder_core::logical_algorithm::StreamingLogicalDecoder; let algo_dec = LogicalAlgorithmDecoder::new(Box::new(full_osd), algo_desc); - let inner = StreamingLogicalDecoder::new(algo_dec); + let inner = pecos_decoder_core::logical_algorithm::StreamingLogicalDecoder::new(algo_dec); Ok(Self { inner }) } @@ -5071,18 +5034,6 @@ impl PyLogicalCircuitDecoder { } let num_qubits = rust_sc.len(); - struct SendWrapper(Box); - unsafe impl Send for SendWrapper {} - unsafe impl Sync for SendWrapper {} - impl pecos_decoders::ObservableDecoder for SendWrapper { - fn decode_to_observables( - &mut self, - syn: &[u8], - ) -> Result { - self.0.decode_to_observables(syn) - } - } - let inner_str = inner_decoder.to_string(); let full_osd = ObservableSubgraphDecoder::from_dem(&full_dem, &rust_sc, |subgraph| { let sub_dem = subgraph_to_dem_string(subgraph); @@ -5167,7 +5118,10 @@ impl PyLogicalCircuitDecoder { // Select budget: "unlimited" for full-circuit, "windowed" for // bounded-latency, or a cycle time in microseconds like "1000us". - let distance = (num_qubits as f64).sqrt() as usize; + let mut distance = 0usize; + while distance.saturating_mul(distance) < num_qubits { + distance += 1; + } let decode_budget = match budget { "unlimited" | "offline" => DecodeBudget::unlimited(), "windowed" => { @@ -5429,11 +5383,11 @@ fn compare_k_body_rates_rs( #[pyfunction] #[pyo3(signature = (mechanisms, target_marginals, max_iterations=200, tolerance=1e-12))] fn fit_dem_to_marginals( - mechanisms: Vec<(f64, Vec, Vec)>, + mechanisms: Vec, target_marginals: Vec, max_iterations: usize, tolerance: f64, -) -> (Vec<(f64, Vec, Vec)>, Vec) { +) -> PyDemFitResult { use pecos_qec::fault_tolerance::correlation::{ DemMechanism, fit_dem_to_marginals as fit_inner, }; @@ -5559,6 +5513,10 @@ pub fn register_qec_module(m: &Bound<'_, PyModule>) -> PyResult<()> { m.add_submodule(&qec)?; + // Keep the common DEM sampler import available at the package root for + // scripts that use `from pecos_rslib import DemSampler`. + m.add("DemSampler", qec.getattr("DemSampler")?)?; + // Register in sys.modules so 'from pecos_rslib.qec import ...' works let sys = m.py().import("sys")?; let modules = sys.getattr("modules")?; diff --git a/python/pecos-rslib/src/lib.rs b/python/pecos-rslib/src/lib.rs index d2c529a08..967cea03a 100644 --- a/python/pecos-rslib/src/lib.rs +++ b/python/pecos-rslib/src/lib.rs @@ -1,4 +1,16 @@ -#![allow(clippy::needless_pass_by_value)] // PyO3 requires owned values from Python +// PyO3 binding signatures are constrained by the Python ABI and generated +// method wrappers. Python docstrings also contain Python snippets that Clippy's +// Rust-doc Markdown lint misclassifies. Keep this list limited to binding/docs +// shape lints. +#![allow( + clippy::doc_markdown, + clippy::missing_errors_doc, + clippy::missing_panics_doc, + clippy::needless_pass_by_value, + clippy::too_many_arguments, + clippy::unnecessary_wraps, + clippy::unused_self +)] #![doc(html_root_url = "https://docs.rs/pecos-rslib")] // Disable doctests since they don't work with our workspace setup #![cfg_attr(docsrs, feature(doc_cfg))] diff --git a/python/quantum-pecos/tests/qec/test_fault_catalog.py b/python/quantum-pecos/tests/qec/test_fault_catalog.py index de2fba19b..2c513bb1e 100644 --- a/python/quantum-pecos/tests/qec/test_fault_catalog.py +++ b/python/quantum-pecos/tests/qec/test_fault_catalog.py @@ -405,7 +405,7 @@ def test_yielded_locations_and_faults(self): def test_tracked_ops_are_distinct_from_observables(self): tc = TickCircuit() tc.tick().h([0]) - tc.pauli_operator(PauliString.from_str("Z"), label="z_probe") + tc.pauli_operator(PauliString.from_str("Z"), label="tracked_z") tc.set_meta("detectors", "[]") tc.set_meta("observables", "[]") From bacaf022c12936c6cdfdb748659e826a5f21bc72 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Fri, 8 May 2026 16:24:30 -0600 Subject: [PATCH 055/125] Remove dem_sampling() alias, keep only meas_sampling() --- python/pecos-rslib-exp/src/lib.rs | 2 - .../pecos-rslib-exp/src/sim_neo_bindings.rs | 52 ++----------- .../quantum-pecos/src/pecos/qec/analysis.py | 27 +++---- .../tests/qec/test_analysis_meas_sampling.py | 20 ----- .../tests/qec/test_meas_sampling_backend.py | 76 +------------------ 5 files changed, 17 insertions(+), 160 deletions(-) diff --git a/python/pecos-rslib-exp/src/lib.rs b/python/pecos-rslib-exp/src/lib.rs index c2f2a4ed2..bf1a8fe67 100644 --- a/python/pecos-rslib-exp/src/lib.rs +++ b/python/pecos-rslib-exp/src/lib.rs @@ -77,10 +77,8 @@ fn pecos_rslib_exp(m: &Bound<'_, PyModule>) -> PyResult<()> { m.add_function(wrap_pyfunction!(sim_neo_bindings::statevec, m)?)?; m.add_function(wrap_pyfunction!(sim_neo_bindings::stabilizer, m)?)?; m.add_class::()?; - m.add_class::()?; m.add_class::()?; m.add_function(wrap_pyfunction!(sim_neo_bindings::meas_sampling, m)?)?; - m.add_function(wrap_pyfunction!(sim_neo_bindings::dem_sampling, m)?)?; m.add_class::()?; m.add_class::()?; m.add_class::()?; diff --git a/python/pecos-rslib-exp/src/sim_neo_bindings.rs b/python/pecos-rslib-exp/src/sim_neo_bindings.rs index 62b1c3148..3152e7d49 100644 --- a/python/pecos-rslib-exp/src/sim_neo_bindings.rs +++ b/python/pecos-rslib-exp/src/sim_neo_bindings.rs @@ -460,43 +460,6 @@ pub fn meas_sampling(method: &str) -> PyMeasSamplingBuilder { PyMeasSamplingBuilder::new(method) } -/// DEM sampling backend builder. -#[pyclass( - name = "DemSamplingBuilder", - skip_from_py_object, - module = "pecos_rslib_exp" -)] -#[derive(Clone)] -pub struct PyDemSamplingBuilder { - method: String, -} - -#[pymethods] -impl PyDemSamplingBuilder { - #[new] - #[pyo3(signature = (method="auto"))] - fn new(method: &str) -> Self { - Self { - method: method.to_string(), - } - } -} - -/// Create a DEM sampling backend builder. -/// -/// Samples raw measurement rows from a detector-error-model measurement -/// model. This is the canonical name for the DEM-backed measurement sampler; -/// `meas_sampling()` remains available as a compatibility alias. -/// -/// Methods: -/// - "auto": uses coherent_dem if idle_rz > 0, else stochastic (default) -/// - "stochastic": DEM from backward Pauli propagation -/// - "coherent": DEM from EEG backward Heisenberg walk -#[pyfunction] -#[pyo3(signature = (method="auto"))] -pub fn dem_sampling(method: &str) -> PyDemSamplingBuilder { - PyDemSamplingBuilder::new(method) -} /// Builder for sim_neo simulations. Mirrors the Rust-side `SimNeoBuilder`. #[pyclass( @@ -533,12 +496,7 @@ impl PySimNeoBuilder { /// sim_neo(tc).quantum(stab_mps().lazy_measure()).noise(...).run() fn quantum(&self, builder: &Bound<'_, PyAny>) -> PyResult { let mut c = self.clone(); - if builder.is_instance_of::() { - let b: PyRef<'_, PyDemSamplingBuilder> = builder.extract()?; - c.backend = "dem_sampling".to_string(); - c.dem_sampling_method = Some(b.method.clone()); - c.stabmps_config = None; - } else if builder.is_instance_of::() { + if builder.is_instance_of::() { let b: PyRef<'_, PyMeasSamplingBuilder> = builder.extract()?; c.backend = "meas_sampling".to_string(); c.dem_sampling_method = Some(b.method.clone()); @@ -558,7 +516,7 @@ impl PySimNeoBuilder { c.dem_sampling_method = None; } else { return Err(pyo3::exceptions::PyTypeError::new_err( - "quantum() expects statevec(), stabilizer(), stab_mps(), dem_sampling(), or meas_sampling()", + "quantum() expects statevec(), stabilizer(), stab_mps(), or meas_sampling()", )); } Ok(c) @@ -590,8 +548,8 @@ impl PySimNeoBuilder { /// All backends return `RawMeasurementResult` which supports: /// `result[shot]`, `result.get(shot, meas)`, `len(result)`, iteration. fn run(&self) -> PyResult { - if self.backend == "dem_sampling" || self.backend == "meas_sampling" { - return self.run_dem_sampling(); + if self.backend == "meas_sampling" { + return self.run_meas_sampling(); } let noise = self @@ -641,7 +599,7 @@ impl PySimNeoBuilder { impl PySimNeoBuilder { /// DEM sampling backend: dispatches to stochastic or coherent path based on method. - fn run_dem_sampling(&self) -> PyResult { + fn run_meas_sampling(&self) -> PyResult { let noise_config = self.noise_config.as_ref().ok_or_else(|| { pyo3::exceptions::PyValueError::new_err("DEM sampling requires .noise() to be set") })?; diff --git a/python/quantum-pecos/src/pecos/qec/analysis.py b/python/quantum-pecos/src/pecos/qec/analysis.py index ca6007734..6ce03c335 100644 --- a/python/quantum-pecos/src/pecos/qec/analysis.py +++ b/python/quantum-pecos/src/pecos/qec/analysis.py @@ -580,9 +580,9 @@ def empirical_correlation_table( shots: Number of simulation shots. max_order: Maximum correlation order (1 = marginals, 2 = pairwise, etc.). backend: Simulator backend — ``"stabilizer"``, ``"statevec"``, - ``"dem_sampling"``, or ``"meas_sampling"``. The DEM sampling - backend uses the fast whole-circuit DEM-based sampler - (geometric/O(fired)) instead of gate-by-gate simulation. + or ``"meas_sampling"``. The meas_sampling backend uses the fast + whole-circuit DEM-based sampler (geometric/O(fired)) instead of + gate-by-gate simulation. seed: RNG seed. Returns: @@ -603,18 +603,16 @@ def empirical_correlation_table( import json from pecos_rslib_exp import ( - dem_sampling, meas_sampling, sim_neo, stabilizer, statevec, ) - if backend in ("dem_sampling", "meas_sampling"): - sampling_backend = dem_sampling() if backend == "dem_sampling" else meas_sampling() + if backend == "meas_sampling": results = ( sim_neo(tick_circuit) - .quantum(sampling_backend) + .quantum(meas_sampling()) .noise(noise_builder) .shots(shots) .seed(seed) @@ -631,7 +629,7 @@ def empirical_correlation_table( .run() ) else: - supported = "'stabilizer', 'statevec', 'dem_sampling', 'meas_sampling'" + supported = "'stabilizer', 'statevec', 'meas_sampling'" raise ValueError( f"Unknown backend {backend!r}. Supported: {supported}." ) @@ -720,9 +718,8 @@ def fit_dem_from_simulation( noise_builder: A noise builder (e.g., ``depolarizing().p1(0.001)``). shots: Number of simulation shots. backend: Simulator backend — ``"stabilizer"``, ``"statevec"``, - ``"dem_sampling"``, or ``"meas_sampling"``. The DEM sampling - backend uses the fast whole-circuit DEM-based sampler instead of - gate-by-gate simulation. + or ``"meas_sampling"``. The meas_sampling backend uses the fast + whole-circuit DEM-based sampler instead of gate-by-gate simulation. seed: RNG seed. max_correlation_order: Max order for empirical rates (1 or 2). @@ -739,7 +736,6 @@ def fit_dem_from_simulation( mechanisms_to_dem_string, ) from pecos_rslib_exp import ( - dem_sampling, meas_sampling, sim_neo, stabilizer, @@ -777,11 +773,10 @@ def fit_dem_from_simulation( num_meas = int(tick_circuit.get_meta("num_measurements")) num_dets = len(det_json) - if backend in ("dem_sampling", "meas_sampling"): - sampling_backend = dem_sampling() if backend == "dem_sampling" else meas_sampling() + if backend == "meas_sampling": results = ( sim_neo(tick_circuit) - .quantum(sampling_backend) + .quantum(meas_sampling()) .noise(noise_builder) .shots(shots) .seed(seed) @@ -798,7 +793,7 @@ def fit_dem_from_simulation( .run() ) else: - supported = "'stabilizer', 'statevec', 'dem_sampling', 'meas_sampling'" + supported = "'stabilizer', 'statevec', 'meas_sampling'" raise ValueError(f"Unknown backend {backend!r}. Supported: {supported}.") inv_shots = 1.0 / shots diff --git a/python/quantum-pecos/tests/qec/test_analysis_meas_sampling.py b/python/quantum-pecos/tests/qec/test_analysis_meas_sampling.py index 7fcc7b1fd..35c0d600d 100644 --- a/python/quantum-pecos/tests/qec/test_analysis_meas_sampling.py +++ b/python/quantum-pecos/tests/qec/test_analysis_meas_sampling.py @@ -20,18 +20,6 @@ def d3_circuit_and_noise(): class TestEmpiricalCorrelationTable: - def test_dem_sampling_returns_nonempty(self, d3_circuit_and_noise): - tc, noise = d3_circuit_and_noise - table = empirical_correlation_table( - tc, - noise, - shots=5000, - max_order=1, - backend="dem_sampling", - seed=42, - ) - assert len(table) > 0, "Should return at least one rate entry" - def test_meas_sampling_returns_nonempty(self, d3_circuit_and_noise): tc, noise = d3_circuit_and_noise table = empirical_correlation_table( @@ -88,14 +76,6 @@ def test_meas_sampling_rates_close_to_stabilizer(self, d3_circuit_and_noise): class TestFitDemFromSimulation: - def test_dem_sampling_returns_dem_string(self, d3_circuit_and_noise): - tc, noise = d3_circuit_and_noise - dem_str = fit_dem_from_simulation( - tc, noise, shots=10000, backend="dem_sampling", seed=42 - ) - assert isinstance(dem_str, str) - assert "error(" in dem_str, "DEM string should contain error(...) lines" - def test_meas_sampling_returns_dem_string(self, d3_circuit_and_noise): tc, noise = d3_circuit_and_noise dem_str = fit_dem_from_simulation( diff --git a/python/quantum-pecos/tests/qec/test_meas_sampling_backend.py b/python/quantum-pecos/tests/qec/test_meas_sampling_backend.py index 1224e7471..2b71586c4 100644 --- a/python/quantum-pecos/tests/qec/test_meas_sampling_backend.py +++ b/python/quantum-pecos/tests/qec/test_meas_sampling_backend.py @@ -12,7 +12,7 @@ from pecos.qec.surface import SurfacePatch from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model -from pecos_rslib_exp import dem_sampling, meas_sampling, depolarizing, sim_neo, stabilizer +from pecos_rslib_exp import meas_sampling, depolarizing, sim_neo, stabilizer @pytest.fixture @@ -184,77 +184,3 @@ def test_no_noise_errors(self, d3_tc): sim_neo(d3_tc).quantum(meas_sampling()).shots(10).seed(42).run() -class TestDemSamplingApi: - def test_dem_sampling_builder_is_exported(self): - assert type(dem_sampling()).__name__ == "DemSamplingBuilder" - - def test_dem_sampling_runs(self, d3_tc, depol): - r = ( - sim_neo(d3_tc) - .quantum(dem_sampling()) - .noise(depol) - .shots(10) - .seed(42) - .run() - ) - assert len(r) == 10 - assert len(r[0]) == 57 - - def test_dem_sampling_matches_meas_sampling_stochastic_same_seed(self, d3_tc, depol): - dem_r = ( - sim_neo(d3_tc) - .quantum(dem_sampling("stochastic")) - .noise(depol) - .shots(25) - .seed(123) - .run() - ) - meas_r = ( - sim_neo(d3_tc) - .quantum(meas_sampling("stochastic")) - .noise(depol) - .shots(25) - .seed(123) - .run() - ) - - assert [dem_r[i] for i in range(len(dem_r))] == [ - meas_r[i] for i in range(len(meas_r)) - ] - - def test_dem_sampling_auto_with_idle_rz(self, d3_tc, coherent): - r = ( - sim_neo(d3_tc) - .quantum(dem_sampling("auto")) - .noise(coherent) - .shots(10) - .seed(42) - .run() - ) - assert len(r[0]) == 57 - - def test_dem_sampling_stochastic_rejects_idle_rz(self, d3_tc, coherent): - with pytest.raises(Exception, match="idle_rz"): - ( - sim_neo(d3_tc) - .quantum(dem_sampling("stochastic")) - .noise(coherent) - .shots(10) - .seed(42) - .run() - ) - - def test_dem_sampling_invalid_method(self, d3_tc, depol): - with pytest.raises(Exception, match="Unknown"): - ( - sim_neo(d3_tc) - .quantum(dem_sampling("bogus")) - .noise(depol) - .shots(10) - .seed(42) - .run() - ) - - def test_dem_sampling_no_noise_errors(self, d3_tc): - with pytest.raises(Exception, match="noise"): - sim_neo(d3_tc).quantum(dem_sampling()).shots(10).seed(42).run() From 443ca0b200d47dfb2f7c68131e5747ac5f595649 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Fri, 8 May 2026 16:26:51 -0600 Subject: [PATCH 056/125] Rename internal dem_sampling_method field to meas_sampling_method --- python/pecos-rslib-exp/src/sim_neo_bindings.rs | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/python/pecos-rslib-exp/src/sim_neo_bindings.rs b/python/pecos-rslib-exp/src/sim_neo_bindings.rs index 3152e7d49..55a577374 100644 --- a/python/pecos-rslib-exp/src/sim_neo_bindings.rs +++ b/python/pecos-rslib-exp/src/sim_neo_bindings.rs @@ -478,7 +478,7 @@ pub struct PySimNeoBuilder { noise_config: Option, backend: String, stabmps_config: Option, - dem_sampling_method: Option, + meas_sampling_method: Option, } #[pymethods] @@ -499,21 +499,21 @@ impl PySimNeoBuilder { if builder.is_instance_of::() { let b: PyRef<'_, PyMeasSamplingBuilder> = builder.extract()?; c.backend = "meas_sampling".to_string(); - c.dem_sampling_method = Some(b.method.clone()); + c.meas_sampling_method = Some(b.method.clone()); c.stabmps_config = None; } else if builder.is_instance_of::() { let b: PyRef<'_, PyStabMpsBuilder> = builder.extract()?; c.backend = "stabmps".to_string(); c.stabmps_config = Some(b.inner.clone()); - c.dem_sampling_method = None; + c.meas_sampling_method = None; } else if builder.is_instance_of::() { c.backend = "stabilizer".to_string(); c.stabmps_config = None; - c.dem_sampling_method = None; + c.meas_sampling_method = None; } else if builder.is_instance_of::() { c.backend = "statevec".to_string(); c.stabmps_config = None; - c.dem_sampling_method = None; + c.meas_sampling_method = None; } else { return Err(pyo3::exceptions::PyTypeError::new_err( "quantum() expects statevec(), stabilizer(), stab_mps(), or meas_sampling()", @@ -604,7 +604,7 @@ impl PySimNeoBuilder { pyo3::exceptions::PyValueError::new_err("DEM sampling requires .noise() to be set") })?; - let method = self.dem_sampling_method.as_deref().unwrap_or("auto"); + let method = self.meas_sampling_method.as_deref().unwrap_or("auto"); let has_coherent = noise_config.idle_rz_angle.abs() > 1e-15; @@ -803,7 +803,7 @@ pub fn py_sim_neo(tick_circuit: &Bound<'_, PyAny>) -> PyResult noise_config: None, backend: "statevec".to_string(), stabmps_config: None, - dem_sampling_method: None, + meas_sampling_method: None, }) } From 258e1846d3f084df51db6d3be1b054ca26f8665d Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Fri, 8 May 2026 21:29:15 -0600 Subject: [PATCH 057/125] Parameterized fault catalog: structural construction, noise separation, zero-prob filtering --- .../src/fault_tolerance/fault_sampler.rs | 768 +++++++++++++----- .../targeted_lookup_decoder.rs | 78 +- design/ENGINES_ARCHITECTURE.md | 3 - design/OPERATOR_TYPE_SYSTEM.md | 3 - design/QIS_ARCHITECTURE.md | 3 - design/STABILIZER_CODE_ARCHITECTURE.md | 3 - design/circuit-representations.md | 3 - design/stn_2d_geometry_backend.md | 3 - design/stn_orthogonal_directions.md | 3 - .../pecos-rslib-exp/src/sim_neo_bindings.rs | 284 +++++-- .../tests/qec/test_fault_catalog.py | 105 +++ .../qec/test_traced_qis_clifford_pipeline.py | 7 +- 12 files changed, 969 insertions(+), 294 deletions(-) delete mode 100644 design/ENGINES_ARCHITECTURE.md delete mode 100644 design/OPERATOR_TYPE_SYSTEM.md delete mode 100644 design/QIS_ARCHITECTURE.md delete mode 100644 design/STABILIZER_CODE_ARCHITECTURE.md delete mode 100644 design/circuit-representations.md delete mode 100644 design/stn_2d_geometry_backend.md delete mode 100644 design/stn_orthogonal_directions.md diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index e13e91448..5420aef5c 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -141,7 +141,7 @@ fn is_supported_noop_or_metadata_gate(gate_type: GateType) -> bool { /// probability p: the mechanism fires with probability p, then each of the /// k alternatives is chosen with probability 1/k. This matches the stabilizer /// sim's "exactly one Pauli error per gate event" semantics. -#[derive(Clone, Debug)] +#[derive(Clone, Debug, PartialEq)] pub struct FaultMechanism { /// Total probability that this mechanism fires (one Bernoulli per shot). pub probability: f64, @@ -222,113 +222,9 @@ pub fn build_fault_table( tc: &TickCircuit, noise: &StochasticNoiseParams, ) -> Result, UnsupportedGateError> { - validate_tick_circuit(tc)?; - let (gates, meas_positions) = flatten_tick_circuit(tc); - - if noise.p1 == 0.0 && noise.p2 == 0.0 && noise.p_meas == 0.0 && noise.p_prep == 0.0 { - return Ok(Vec::new()); - } - let mut mechanisms = Vec::new(); - - for (loc_idx, loc) in gates.iter().enumerate() { - match loc.gate_type { - // Single-qubit Clifford: one mechanism with 3 alternatives (X/Y/Z) - gate_type - if is_standard_1q_clifford_gate(gate_type) - && noise.p1 > 0.0 - && !loc.qubits.is_empty() => - { - let q = loc.qubits[0]; - let alts: Vec> = [PauliType::X, PauliType::Y, PauliType::Z] - .iter() - .map(|&p| { - propagate_single(p, q, loc_idx + 1, &gates, &meas_positions) - .into_iter() - .collect() - }) - .collect(); - // Only include if at least one alternative has an effect - if alts.iter().any(|a| !a.is_empty()) { - mechanisms.push(FaultMechanism { - probability: noise.p1, - alternatives: alts, - }); - } - } - - // Two-qubit Clifford: one mechanism with 15 alternatives - gate_type - if is_standard_2q_clifford_gate(gate_type) - && noise.p2 > 0.0 - && loc.qubits.len() >= 2 => - { - let (q1, q2) = (loc.qubits[0], loc.qubits[1]); - let paulis = [PauliType::X, PauliType::Y, PauliType::Z]; - let mut alts: Vec> = Vec::new(); - - // 9 two-qubit pairs - for &p1 in &paulis { - for &p2 in &paulis { - let a: Vec = - propagate_pair(p1, q1, p2, q2, loc_idx + 1, &gates, &meas_positions) - .into_iter() - .collect(); - alts.push(a); - } - } - // 6 single-qubit (PI and IP) - for &p in &paulis { - let a: Vec = - propagate_single(p, q1, loc_idx + 1, &gates, &meas_positions) - .into_iter() - .collect(); - alts.push(a); - let a: Vec = - propagate_single(p, q2, loc_idx + 1, &gates, &meas_positions) - .into_iter() - .collect(); - alts.push(a); - } - if alts.iter().any(|a| !a.is_empty()) { - mechanisms.push(FaultMechanism { - probability: noise.p2, - alternatives: alts, - }); - } - } - - // State preparation: single alternative (X error) - GateType::PZ | GateType::QAlloc if noise.p_prep > 0.0 && !loc.qubits.is_empty() => { - let q = loc.qubits[0]; - let a: Vec = - propagate_single(PauliType::X, q, loc_idx + 1, &gates, &meas_positions) - .into_iter() - .collect(); - if !a.is_empty() { - mechanisms.push(FaultMechanism { - probability: noise.p_prep, - alternatives: vec![a], - }); - } - } - - // Measurement fault: single alternative (flip this measurement) - GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked - if noise.p_meas > 0.0 => - { - if let Some(&meas_idx) = meas_positions.get(&loc_idx) { - mechanisms.push(FaultMechanism { - probability: noise.p_meas, - alternatives: vec![vec![meas_idx]], - }); - } - } - - _ => {} - } - } - - Ok(mechanisms) + let mut catalog = FaultCatalog::from_circuit(tc)?; + catalog.with_noise(noise); + Ok(catalog.to_mechanisms()) } /// Validate that all gates in the `TickCircuit` are supported (before flattening). @@ -413,6 +309,7 @@ pub(crate) fn flatten_tick_circuit(tc: &TickCircuit) -> (Vec, HashMap, -) -> BTreeSet { - let mut prop = PauliProp::new(); - match p1 { - PauliType::X => prop.track_x(&[q1]), - PauliType::Y => prop.track_y(&[q1]), - PauliType::Z => prop.track_z(&[q1]), - } - match p2 { - PauliType::X => prop.track_x(&[q2]), - PauliType::Y => prop.track_y(&[q2]), - PauliType::Z => prop.track_z(&[q2]), - } - - propagate_forward(&mut prop, start, gates, meas_positions) -} - fn propagate_pair_effect( faults: [(PauliType, usize); 2], start: usize, @@ -624,7 +496,7 @@ pub enum FaultKind { } /// Which noise channel produced this fault location. -#[derive(Clone, Debug, PartialEq, Eq)] +#[derive(Clone, Copy, Debug, PartialEq, Eq)] pub enum FaultChannel { /// Single-qubit depolarizing (`p1`). P1, @@ -730,12 +602,99 @@ pub struct FaultConfiguration { } impl FaultCatalog { + /// Build a structural fault catalog from a circuit. + /// + /// The returned catalog includes all structurally supported noisy locations, + /// independent of any concrete noise point. All channel and alternative + /// probabilities are initialized to zero except `no_fault_probability`, which + /// is initialized to one. + /// + /// # Errors + /// + /// Returns [`UnsupportedGateError`] when the circuit contains a gate outside + /// the supported Clifford/prep/measurement/metadata set. + pub fn from_circuit(tc: &TickCircuit) -> Result { + build_structural_fault_catalog(tc) + } + + /// Recompute noise-dependent probability fields for this catalog. + /// + /// This updates only `channel_probability`, `no_fault_probability`, and + /// `absolute_probability`. Structural fields such as `num_alternatives`, + /// `conditional_probability`, Pauli labels, and effect lists are unchanged. + /// + /// # Panics + /// + /// Panics if a malformed catalog contains more than `u32::MAX` alternatives + /// at one location. Catalogs produced by [`FaultCatalog::from_circuit`] have + /// at most 15 alternatives per location. + pub fn with_noise(&mut self, noise: &StochasticNoiseParams) -> &mut Self { + for loc in &mut self.locations { + let p = match loc.channel { + FaultChannel::P1 => noise.p1, + FaultChannel::P2 => noise.p2, + FaultChannel::PMeas => noise.p_meas, + FaultChannel::PPrep => noise.p_prep, + }; + let k = loc.num_alternatives; + debug_assert!(k > 0, "fault location has no alternatives"); + debug_assert_eq!(k, loc.faults.len(), "num_alternatives out of sync"); + let k_f64 = f64::from(u32::try_from(k).expect("fault alternative count exceeds u32")); + + loc.channel_probability = p; + loc.no_fault_probability = 1.0 - p; + for alt in &mut loc.faults { + alt.absolute_probability = p / k_f64; + } + } + self + } + + /// Clone this catalog and apply a concrete noise point to the clone. + #[must_use] + pub fn parameterized(&self, noise: &StochasticNoiseParams) -> Self { + let mut copy = self.clone(); + copy.with_noise(noise); + copy + } + + /// Convert this catalog into raw-measurement sampling mechanisms. + /// + /// This is a materialization step for raw measurement sampling only. It + /// drops zero-probability locations and locations where every alternative has + /// empty `affected_measurements`, while preserving empty alternatives inside + /// any kept mechanism to maintain the correct uniform denominator. + #[must_use] + pub fn to_mechanisms(&self) -> Vec { + self.locations + .iter() + .filter(|loc| loc.channel_probability > 0.0) + .filter(|loc| { + loc.faults + .iter() + .any(|alt| !alt.affected_measurements.is_empty()) + }) + .map(|loc| FaultMechanism { + probability: loc.channel_probability, + alternatives: loc + .faults + .iter() + .map(|alt| alt.affected_measurements.clone()) + .collect(), + }) + .collect() + } + /// Lazily iterate all k-fault configurations. /// /// Each yielded `FaultConfiguration` represents exactly k distinct locations /// firing, with one alternative chosen per location. Effects are combined by /// XOR parity. Probabilities follow the independent-mechanism model. /// + /// Zero-probability alternatives are skipped. A structural location with + /// `channel_probability == 0` remains in [`FaultCatalog::locations`] but is + /// not yielded as a selected fault configuration. + /// /// For k=0: yields one no-fault event. #[must_use] pub fn fault_configurations(&self, k: usize) -> FaultConfigurationIter<'_> { @@ -747,8 +706,12 @@ impl FaultCatalog { /// /// Holds the combination/alternative state machine. Shared by both /// `FaultConfigurationIter` (borrowed) and `OwnedFaultConfigIter` (owned). +/// Combinations range over nonzero-probability fault alternatives only; the +/// full structural catalog remains available through `FaultCatalog::locations`. struct FaultConfigCursor { k: usize, + location_indices: Vec, + alternative_indices: Vec>, combo: Vec, alt_indices: Vec, alt_counts: Vec, @@ -757,22 +720,45 @@ struct FaultConfigCursor { } impl FaultConfigCursor { - fn new(num_locations: usize, k: usize, alt_count_fn: impl Fn(usize) -> usize) -> Self { - if k == 0 || k > num_locations { + fn new(catalog: &FaultCatalog, k: usize) -> Self { + let mut location_indices = Vec::new(); + let mut alternative_indices = Vec::new(); + for (loc_idx, loc) in catalog.locations.iter().enumerate() { + let alts: Vec = loc + .faults + .iter() + .enumerate() + .filter_map(|(alt_idx, alt)| (alt.absolute_probability > 0.0).then_some(alt_idx)) + .collect(); + if !alts.is_empty() { + location_indices.push(loc_idx); + alternative_indices.push(alts); + } + } + + let num_active_locations = location_indices.len(); + if k == 0 || k > num_active_locations { return Self { k, + location_indices, + alternative_indices, combo: Vec::new(), alt_indices: Vec::new(), alt_counts: Vec::new(), started: false, - done: k > num_locations && k > 0, + done: k > num_active_locations && k > 0, }; } let combo: Vec = (0..k).collect(); - let alt_counts: Vec = combo.iter().map(|&i| alt_count_fn(i)).collect(); + let alt_counts: Vec = combo + .iter() + .map(|&i| alternative_indices[i].len()) + .collect(); let alt_indices = vec![0usize; k]; Self { k, + location_indices, + alternative_indices, combo, alt_indices, alt_counts, @@ -782,7 +768,7 @@ impl FaultConfigCursor { } /// Advance to the next state. Returns true if a new valid state exists. - fn advance(&mut self, num_locations: usize, alt_count_fn: impl Fn(usize) -> usize) -> bool { + fn advance(&mut self) -> bool { // Try advancing alternatives (mixed-radix counter) for i in (0..self.k).rev() { self.alt_indices[i] += 1; @@ -796,12 +782,12 @@ impl FaultConfigCursor { while i > 0 { i -= 1; self.combo[i] += 1; - if self.combo[i] <= num_locations - self.k + i { + if self.combo[i] <= self.location_indices.len() - self.k + i { for j in (i + 1)..self.k { self.combo[j] = self.combo[j - 1] + 1; } for j in 0..self.k { - self.alt_counts[j] = alt_count_fn(self.combo[j]); + self.alt_counts[j] = self.alternative_indices[self.combo[j]].len(); self.alt_indices[j] = 0; } return true; @@ -837,8 +823,10 @@ impl FaultConfigCursor { let mut selected_prob = 1.0; for i in 0..self.k { - let loc = &catalog.locations[self.combo[i]]; - let alt = &loc.faults[self.alt_indices[i]]; + let location_index = self.location_indices[self.combo[i]]; + let alternative_index = self.alternative_indices[self.combo[i]][self.alt_indices[i]]; + let loc = &catalog.locations[location_index]; + let alt = &loc.faults[alternative_index]; selected_prob *= alt.absolute_probability; for &m in &alt.affected_measurements { if !meas_set.remove(&m) { @@ -862,7 +850,11 @@ impl FaultConfigCursor { } } - let selected_set: std::collections::BTreeSet = self.combo.iter().copied().collect(); + let selected_set: std::collections::BTreeSet = self + .combo + .iter() + .map(|&i| self.location_indices[i]) + .collect(); let unselected_no_fault: f64 = catalog .locations .iter() @@ -872,8 +864,17 @@ impl FaultConfigCursor { .product(); FaultConfiguration { - location_indices: self.combo.clone(), - alternative_indices: self.alt_indices.clone(), + location_indices: self + .combo + .iter() + .map(|&i| self.location_indices[i]) + .collect(), + alternative_indices: self + .combo + .iter() + .zip(self.alt_indices.iter()) + .map(|(&loc_pos, &alt_pos)| self.alternative_indices[loc_pos][alt_pos]) + .collect(), affected_measurements: meas_set.into_iter().collect(), affected_detectors: det_set.into_iter().collect(), affected_observables: obs_set.into_iter().collect(), @@ -896,8 +897,7 @@ impl FaultConfigCursor { self.started = true; return Some(self.build(catalog)); } - let n = catalog.locations.len(); - if self.advance(n, |i| catalog.locations[i].faults.len()) { + if self.advance() { Some(self.build(catalog)) } else { self.done = true; @@ -914,9 +914,7 @@ pub struct FaultConfigurationIter<'a> { impl<'a> FaultConfigurationIter<'a> { fn new(catalog: &'a FaultCatalog, k: usize) -> Self { - let cursor = FaultConfigCursor::new(catalog.locations.len(), k, |i| { - catalog.locations[i].faults.len() - }); + let cursor = FaultConfigCursor::new(catalog, k); Self { catalog, cursor } } } @@ -939,9 +937,7 @@ impl OwnedFaultConfigIter { /// Create from an owned catalog clone. #[must_use] pub fn new(catalog: FaultCatalog, k: usize) -> Self { - let cursor = FaultConfigCursor::new(catalog.locations.len(), k, |i| { - catalog.locations[i].faults.len() - }); + let cursor = FaultConfigCursor::new(&catalog, k); Self { catalog, cursor } } } @@ -969,6 +965,12 @@ pub fn build_fault_catalog( tc: &TickCircuit, noise: &StochasticNoiseParams, ) -> Result { + let mut catalog = FaultCatalog::from_circuit(tc)?; + catalog.with_noise(noise); + Ok(catalog) +} + +fn build_structural_fault_catalog(tc: &TickCircuit) -> Result { validate_tick_circuit(tc)?; let (gates, meas_positions) = flatten_tick_circuit(tc); @@ -1040,15 +1042,10 @@ pub fn build_fault_catalog( let (tick_idx, gate_idx, gate_type, ref qubits) = flat_idx_to_tick_gate[loc_idx]; match loc.gate_type { - gate_type - if is_standard_1q_clifford_gate(gate_type) - && noise.p1 > 0.0 - && !loc.qubits.is_empty() => - { + gate_type if is_standard_1q_clifford_gate(gate_type) && !loc.qubits.is_empty() => { let q = loc.qubits[0]; let num_alts = 3; let conditional_probability = 1.0 / 3.0; - let absolute_probability = noise.p1 / 3.0; let mut faults = Vec::with_capacity(num_alts); for &pt in &pauli_types { let effect = propagate_single_effect( @@ -1070,10 +1067,9 @@ pub fn build_fault_catalog( affected_observables: obs, affected_tracked_ops: tracked, conditional_probability, - absolute_probability, + absolute_probability: 0.0, }); } - // Include all locations with nonzero channel probability (even no-effect ones) let num_alts = faults.len(); locations.push(FaultLocation { tick: tick_idx, @@ -1081,22 +1077,17 @@ pub fn build_fault_catalog( gate_type, qubits: qubits.clone(), channel: FaultChannel::P1, - channel_probability: noise.p1, - no_fault_probability: 1.0 - noise.p1, + channel_probability: 0.0, + no_fault_probability: 1.0, num_alternatives: num_alts, faults, }); } - gate_type - if is_standard_2q_clifford_gate(gate_type) - && noise.p2 > 0.0 - && loc.qubits.len() >= 2 => - { + gate_type if is_standard_2q_clifford_gate(gate_type) && loc.qubits.len() >= 2 => { let (q1, q2) = (loc.qubits[0], loc.qubits[1]); let num_alts = 15; let conditional_probability = 1.0 / 15.0; - let absolute_probability = noise.p2 / 15.0; let mut faults = Vec::with_capacity(num_alts); // 9 two-qubit pairs @@ -1120,7 +1111,7 @@ pub fn build_fault_catalog( affected_observables: obs, affected_tracked_ops: tracked, conditional_probability, - absolute_probability, + absolute_probability: 0.0, }); } } @@ -1145,7 +1136,7 @@ pub fn build_fault_catalog( affected_observables: obs, affected_tracked_ops: tracked, conditional_probability, - absolute_probability, + absolute_probability: 0.0, }); let effect = propagate_single_effect( @@ -1167,7 +1158,7 @@ pub fn build_fault_catalog( affected_observables: obs, affected_tracked_ops: tracked, conditional_probability, - absolute_probability, + absolute_probability: 0.0, }); } let n_alts = faults.len(); @@ -1177,14 +1168,14 @@ pub fn build_fault_catalog( gate_type, qubits: qubits.clone(), channel: FaultChannel::P2, - channel_probability: noise.p2, - no_fault_probability: 1.0 - noise.p2, + channel_probability: 0.0, + no_fault_probability: 1.0, num_alternatives: n_alts, faults, }); } - GateType::PZ | GateType::QAlloc if noise.p_prep > 0.0 && !loc.qubits.is_empty() => { + GateType::PZ | GateType::QAlloc if !loc.qubits.is_empty() => { let q = loc.qubits[0]; let effect = propagate_single_effect( PauliType::X, @@ -1202,8 +1193,8 @@ pub fn build_fault_catalog( gate_type, qubits: qubits.clone(), channel: FaultChannel::PPrep, - channel_probability: noise.p_prep, - no_fault_probability: 1.0 - noise.p_prep, + channel_probability: 0.0, + no_fault_probability: 1.0, num_alternatives: 1, faults: vec![FaultAlternative { kind: FaultKind::PrepFlip, @@ -1213,14 +1204,12 @@ pub fn build_fault_catalog( affected_observables: obs, affected_tracked_ops: tracked, conditional_probability: 1.0, - absolute_probability: noise.p_prep, + absolute_probability: 0.0, }], }); } - GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked - if noise.p_meas > 0.0 => - { + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked => { if let Some(&meas_idx) = meas_positions.get(&loc_idx) { let affected = vec![meas_idx]; let dets = measurements_to_detectors(&affected, &det_records, num_meas); @@ -1231,8 +1220,8 @@ pub fn build_fault_catalog( gate_type, qubits: qubits.clone(), channel: FaultChannel::PMeas, - channel_probability: noise.p_meas, - no_fault_probability: 1.0 - noise.p_meas, + channel_probability: 0.0, + no_fault_probability: 1.0, num_alternatives: 1, faults: vec![FaultAlternative { kind: FaultKind::MeasurementFlip, @@ -1242,7 +1231,7 @@ pub fn build_fault_catalog( affected_observables: obs, affected_tracked_ops: Vec::new(), conditional_probability: 1.0, - absolute_probability: noise.p_meas, + absolute_probability: 0.0, }], }); } @@ -2708,6 +2697,271 @@ mod tests { ); } + #[test] + fn test_structural_catalog_includes_zero_probability_locations() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".to_string()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String("[]".to_string()), + ); + tc.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let catalog = FaultCatalog::from_circuit(&tc).unwrap(); + assert_eq!(catalog.locations.len(), 2); + assert!( + catalog + .locations + .iter() + .all(|loc| loc.channel_probability == 0.0) + ); + assert!( + catalog + .locations + .iter() + .all(|loc| loc.no_fault_probability == 1.0) + ); + assert!( + catalog + .locations + .iter() + .flat_map(|loc| &loc.faults) + .all(|fault| fault.absolute_probability == 0.0) + ); + assert!( + catalog + .locations + .iter() + .any(|loc| loc.channel == FaultChannel::P1) + ); + assert!( + catalog + .locations + .iter() + .any(|loc| loc.channel == FaultChannel::PMeas) + ); + } + + #[test] + fn test_parameterized_matches_direct_for_fully_nonzero_noise() { + let mut tc = TickCircuit::new(); + tc.tick().pz(&[QubitId(0)]); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".to_string()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String(r#"[{"records":[-1]}]"#.to_string()), + ); + tc.set_meta( + "observables", + pecos_quantum::Attribute::String(r#"[{"records":[-1]}]"#.to_string()), + ); + + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.02, + p_meas: 0.01, + p_prep: 0.004, + }; + let direct = build_fault_catalog(&tc, &noise).unwrap(); + let mut split = FaultCatalog::from_circuit(&tc).unwrap(); + split.with_noise(&noise); + + assert_eq!(direct.locations.len(), split.locations.len()); + for (a, b) in direct.locations.iter().zip(&split.locations) { + assert_eq!(a.tick, b.tick); + assert_eq!(a.gate_index, b.gate_index); + assert_eq!(a.gate_type, b.gate_type); + assert_eq!(a.qubits, b.qubits); + assert_eq!(a.channel, b.channel); + assert_eq!(a.channel_probability, b.channel_probability); + assert_eq!(a.no_fault_probability, b.no_fault_probability); + assert_eq!(a.num_alternatives, b.num_alternatives); + assert_eq!(a.faults.len(), b.faults.len()); + for (af, bf) in a.faults.iter().zip(&b.faults) { + assert_eq!(af.kind, bf.kind); + assert_eq!(af.pauli, bf.pauli); + assert_eq!(af.affected_measurements, bf.affected_measurements); + assert_eq!(af.affected_detectors, bf.affected_detectors); + assert_eq!(af.affected_observables, bf.affected_observables); + assert_eq!(af.affected_tracked_ops, bf.affected_tracked_ops); + assert_eq!(af.conditional_probability, bf.conditional_probability); + assert_eq!(af.absolute_probability, bf.absolute_probability); + } + } + } + + #[test] + fn test_with_noise_overwrites_previous_probabilities() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".to_string()), + ); + + let mut catalog = FaultCatalog::from_circuit(&tc).unwrap(); + catalog.with_noise(&StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }); + catalog.with_noise(&StochasticNoiseParams { + p1: 0.09, + p2: 0.0, + p_meas: 0.02, + p_prep: 0.0, + }); + + let h_loc = catalog + .locations + .iter() + .find(|loc| loc.channel == FaultChannel::P1) + .unwrap(); + assert_eq!(h_loc.channel_probability, 0.09); + assert_eq!(h_loc.no_fault_probability, 0.91); + assert!( + h_loc + .faults + .iter() + .all(|fault| (fault.absolute_probability - 0.03).abs() < 1e-12) + ); + + let meas_loc = catalog + .locations + .iter() + .find(|loc| loc.channel == FaultChannel::PMeas) + .unwrap(); + assert_eq!(meas_loc.channel_probability, 0.02); + assert_eq!(meas_loc.faults[0].absolute_probability, 0.02); + } + + #[test] + fn test_sparse_channel_keeps_structure_but_filters_raw_mechanisms() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".to_string()), + ); + + let noise = StochasticNoiseParams { + p1: 0.0, + p2: 0.0, + p_meas: 0.02, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + assert_eq!(catalog.locations.len(), 2); + assert!( + catalog + .locations + .iter() + .any(|loc| loc.channel == FaultChannel::P1 && loc.channel_probability == 0.0) + ); + + let mechanisms = catalog.to_mechanisms(); + assert_eq!(mechanisms.len(), 1); + assert_eq!(mechanisms[0].probability, 0.02); + assert_eq!(mechanisms[0].alternatives, vec![vec![0]]); + assert_eq!(mechanisms, build_fault_table(&tc, &noise).unwrap()); + } + + #[test] + fn test_tracked_only_effect_stays_in_catalog_but_not_raw_mechanisms() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.pauli_operator_labeled("tracked_z0", PauliString::z(0)); + + let mut catalog = FaultCatalog::from_circuit(&tc).unwrap(); + catalog.with_noise(&StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }); + + let h_loc = catalog + .locations + .iter() + .find(|loc| loc.channel == FaultChannel::P1) + .unwrap(); + assert!(h_loc.faults.iter().any(|fault| { + fault.affected_measurements.is_empty() && !fault.affected_tracked_ops.is_empty() + })); + assert!(catalog.to_mechanisms().is_empty()); + } + + #[test] + fn test_to_mechanisms_matches_old_build_fault_table() { + // The key invariant: catalog.to_mechanisms() must produce the same + // mechanisms as the old build_fault_table path for nonzero noise. + let mut tc = TickCircuit::new(); + tc.tick().pz(&[QubitId(0), QubitId(1)]); + tc.tick().h(&[QubitId(0)]); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(0), QubitId(1)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("2".to_string()), + ); + tc.set_meta( + "detectors", + pecos_quantum::Attribute::String("[]".to_string()), + ); + tc.set_meta( + "observables", + pecos_quantum::Attribute::String("[]".to_string()), + ); + + let noise = StochasticNoiseParams { + p1: 0.01, + p2: 0.05, + p_meas: 0.02, + p_prep: 0.01, + }; + + // Old path (now a wrapper, but the output must match): + let old_mechanisms = build_fault_table(&tc, &noise).unwrap(); + + // New path: + let mut catalog = FaultCatalog::from_circuit(&tc).unwrap(); + catalog.with_noise(&noise); + let new_mechanisms = catalog.to_mechanisms(); + + assert_eq!( + old_mechanisms.len(), + new_mechanisms.len(), + "mechanism count must match" + ); + for (old, new) in old_mechanisms.iter().zip(&new_mechanisms) { + assert_eq!(old.probability, new.probability, "probability must match"); + assert_eq!( + old.alternatives.len(), + new.alternatives.len(), + "alternative count must match" + ); + for (old_alt, new_alt) in old.alternatives.iter().zip(&new.alternatives) { + assert_eq!(old_alt, new_alt, "measurement effects must match"); + } + } + } + #[test] fn test_catalog_meas_prep_probabilities() { // PZ(0) MZ(0): prep X fault goes directly to MZ (flips it) @@ -2911,6 +3165,148 @@ mod tests { assert!((c.selected_probability - alt.absolute_probability).abs() < 1e-12); } + #[test] + fn test_configurations_skip_zero_probability_structural_locations() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".into()), + ); + tc.set_meta("detectors", pecos_quantum::Attribute::String("[]".into())); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }; + let catalog = build_fault_catalog(&tc, &noise).unwrap(); + assert_eq!(catalog.locations.len(), 2); + + let h_idx = catalog + .locations + .iter() + .position(|loc| loc.gate_type == GateType::H) + .unwrap(); + let mz_idx = catalog + .locations + .iter() + .position(|loc| loc.gate_type == GateType::MZ) + .unwrap(); + assert_eq!(catalog.locations[mz_idx].channel_probability, 0.0); + + let configs: Vec<_> = catalog.fault_configurations(1).collect(); + assert_eq!(configs.len(), 3); + assert!(configs.iter().all(|c| c.location_indices == vec![h_idx])); + assert!(configs.iter().all(|c| c.selected_probability > 0.0)); + assert!( + configs + .iter() + .all(|c| !c.location_indices.contains(&mz_idx)) + ); + assert_eq!(catalog.fault_configurations(2).count(), 0); + } + + #[test] + fn test_configurations_all_zero_noise_only_yields_k0() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".into()), + ); + tc.set_meta("detectors", pecos_quantum::Attribute::String("[]".into())); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let catalog = build_fault_catalog( + &tc, + &StochasticNoiseParams { + p1: 0.0, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + + let k0: Vec<_> = catalog.fault_configurations(0).collect(); + assert_eq!(k0.len(), 1); + assert_eq!(k0[0].configuration_probability, 1.0); + assert_eq!(catalog.fault_configurations(1).count(), 0); + assert_eq!(catalog.fault_configurations(2).count(), 0); + } + + #[test] + fn test_configurations_include_nonzero_silent_faults() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("0".into()), + ); + tc.set_meta("detectors", pecos_quantum::Attribute::String("[]".into())); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let catalog = build_fault_catalog( + &tc, + &StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + + let configs: Vec<_> = catalog.fault_configurations(1).collect(); + assert_eq!(configs.len(), 3); + assert!(configs.iter().all(|c| c.affected_measurements.is_empty())); + assert!(configs.iter().all(|c| c.affected_detectors.is_empty())); + assert!(configs.iter().all(|c| c.affected_observables.is_empty())); + assert!(configs.iter().all(|c| c.selected_probability > 0.0)); + } + + #[test] + fn test_configurations_with_noise_zeroes_previous_channel() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".into()), + ); + tc.set_meta("detectors", pecos_quantum::Attribute::String("[]".into())); + tc.set_meta("observables", pecos_quantum::Attribute::String("[]".into())); + + let mut catalog = FaultCatalog::from_circuit(&tc).unwrap(); + catalog.with_noise(&StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }); + catalog.with_noise(&StochasticNoiseParams { + p1: 0.0, + p2: 0.0, + p_meas: 0.02, + p_prep: 0.0, + }); + + let mz_idx = catalog + .locations + .iter() + .position(|loc| loc.gate_type == GateType::MZ) + .unwrap(); + let configs: Vec<_> = catalog.fault_configurations(1).collect(); + assert_eq!(configs.len(), 1); + assert_eq!(configs[0].location_indices, vec![mz_idx]); + assert_eq!(configs[0].selected_probability, 0.02); + } + #[test] fn test_configurations_k2_xor_cancels_duplicate_effects() { // Two H gates both flipping measurement 0 → XOR cancels @@ -2935,7 +3331,7 @@ mod tests { p_prep: 0.0, }; let catalog = build_fault_catalog(&tc, &noise).unwrap(); - assert_eq!(catalog.locations.len(), 2); + assert_eq!(catalog.locations.len(), 3); // two H locations + structural MZ location // Find a k=2 config where both locations fire with Z alternative (flips MZ) // Z after first H → X at second H → X at MZ → flips meas 0 diff --git a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs index 54c90b492..e364c1cfc 100644 --- a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs +++ b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs @@ -89,6 +89,9 @@ impl TargetedLookupDecoder { } else { f64::INFINITY }; + if odds == 0.0 { + continue; + } entries.push(FaultEntry { location_index: loc_idx, detector_bits: alt.affected_detectors.iter().copied().collect(), @@ -276,7 +279,8 @@ fn xor_sets(a: &BTreeSet, b: &BTreeSet) -> BTreeSet { mod tests { use super::*; use crate::fault_tolerance::fault_sampler::{ - FaultCatalog, StochasticNoiseParams, build_fault_catalog, + FaultAlternative, FaultCatalog, FaultKind, FaultLocation, StochasticNoiseParams, + build_fault_catalog, }; use pecos_core::{QubitId, gate_type::GateType}; use pecos_quantum::TickCircuit; @@ -354,6 +358,78 @@ mod tests { assert!((result.logical_weights[&vec![]] - 1.0).abs() < 1e-12); } + #[test] + fn test_unparameterized_catalog_has_no_positive_fault_weights() { + let catalog = FaultCatalog::from_circuit(&tiny_circuit()).unwrap(); + let decoder = TargetedLookupDecoder::new(&catalog).max_faults(2); + + let empty = decoder.decode(&[]); + assert_eq!(empty.logical_weights.len(), 1); + assert_eq!(empty.logical_weights[&vec![]], 1.0); + + let non_empty = decoder.decode(&[0]); + assert!( + non_empty.logical_weights.is_empty(), + "zero-probability structural faults must not create zero-weight classes" + ); + } + + #[test] + fn test_zero_probability_alternatives_are_ignored() { + let catalog = FaultCatalog { + locations: vec![ + FaultLocation { + tick: 0, + gate_index: 0, + gate_type: GateType::H, + qubits: vec![0], + channel: crate::fault_tolerance::fault_sampler::FaultChannel::P1, + channel_probability: 0.0, + no_fault_probability: 1.0, + num_alternatives: 1, + faults: vec![FaultAlternative { + kind: FaultKind::Pauli, + pauli: None, + affected_measurements: Vec::new(), + affected_detectors: vec![0], + affected_observables: vec![9], + affected_tracked_ops: Vec::new(), + conditional_probability: 1.0, + absolute_probability: 0.0, + }], + }, + FaultLocation { + tick: 1, + gate_index: 0, + gate_type: GateType::MZ, + qubits: vec![0], + channel: crate::fault_tolerance::fault_sampler::FaultChannel::PMeas, + channel_probability: 0.1, + no_fault_probability: 0.9, + num_alternatives: 1, + faults: vec![FaultAlternative { + kind: FaultKind::MeasurementFlip, + pauli: None, + affected_measurements: vec![0], + affected_detectors: vec![0], + affected_observables: Vec::new(), + affected_tracked_ops: Vec::new(), + conditional_probability: 1.0, + absolute_probability: 0.1, + }], + }, + ], + }; + + let result = TargetedLookupDecoder::new(&catalog) + .max_faults(1) + .decode(&[0]); + + assert!(!result.logical_weights.contains_key(&vec![9])); + assert_eq!(result.logical_weights.len(), 1); + assert!((result.logical_weights[&vec![]] - (0.1 / 0.9)).abs() < 1e-12); + } + #[test] fn test_unexplainable_syndrome_returns_empty_weights() { let mut tc = TickCircuit::new(); diff --git a/design/ENGINES_ARCHITECTURE.md b/design/ENGINES_ARCHITECTURE.md deleted file mode 100644 index 72bfd9133..000000000 --- a/design/ENGINES_ARCHITECTURE.md +++ /dev/null @@ -1,3 +0,0 @@ -# Moved to pecos-docs vault - -This document has been moved to `~/Repos/pecos-docs/design/engines-architecture.md`. diff --git a/design/OPERATOR_TYPE_SYSTEM.md b/design/OPERATOR_TYPE_SYSTEM.md deleted file mode 100644 index 532d2e099..000000000 --- a/design/OPERATOR_TYPE_SYSTEM.md +++ /dev/null @@ -1,3 +0,0 @@ -# Moved to pecos-docs vault - -This document has been moved to `~/Repos/pecos-docs/design/operator-type-system.md`. diff --git a/design/QIS_ARCHITECTURE.md b/design/QIS_ARCHITECTURE.md deleted file mode 100644 index 03331b6a2..000000000 --- a/design/QIS_ARCHITECTURE.md +++ /dev/null @@ -1,3 +0,0 @@ -# Moved to pecos-docs vault - -This document has been moved to `~/Repos/pecos-docs/design/qis-architecture.md`. diff --git a/design/STABILIZER_CODE_ARCHITECTURE.md b/design/STABILIZER_CODE_ARCHITECTURE.md deleted file mode 100644 index b121b1859..000000000 --- a/design/STABILIZER_CODE_ARCHITECTURE.md +++ /dev/null @@ -1,3 +0,0 @@ -# Moved to pecos-docs vault - -This document has been moved to `~/Repos/pecos-docs/design/stabilizer-code-architecture.md`. diff --git a/design/circuit-representations.md b/design/circuit-representations.md deleted file mode 100644 index 746dd7601..000000000 --- a/design/circuit-representations.md +++ /dev/null @@ -1,3 +0,0 @@ -# Moved to pecos-docs vault - -This document has been moved to `~/Repos/pecos-docs/design/circuit-representations.md`. diff --git a/design/stn_2d_geometry_backend.md b/design/stn_2d_geometry_backend.md deleted file mode 100644 index 26b9552f0..000000000 --- a/design/stn_2d_geometry_backend.md +++ /dev/null @@ -1,3 +0,0 @@ -# Moved to pecos-docs vault - -This document has been moved to `~/Repos/pecos-docs/design/stab-tn/2d-geometry-backend.md`. diff --git a/design/stn_orthogonal_directions.md b/design/stn_orthogonal_directions.md deleted file mode 100644 index 2c1ebef8c..000000000 --- a/design/stn_orthogonal_directions.md +++ /dev/null @@ -1,3 +0,0 @@ -# Moved to pecos-docs vault - -This document has been moved to `~/Repos/pecos-docs/design/stab-tn/orthogonal-directions.md`. diff --git a/python/pecos-rslib-exp/src/sim_neo_bindings.rs b/python/pecos-rslib-exp/src/sim_neo_bindings.rs index 55a577374..8adbf3b11 100644 --- a/python/pecos-rslib-exp/src/sim_neo_bindings.rs +++ b/python/pecos-rslib-exp/src/sim_neo_bindings.rs @@ -460,7 +460,6 @@ pub fn meas_sampling(method: &str) -> PyMeasSamplingBuilder { PyMeasSamplingBuilder::new(method) } - /// Builder for sim_neo simulations. Mirrors the Rust-side `SimNeoBuilder`. #[pyclass( name = "SimNeoBuilder", @@ -1447,100 +1446,55 @@ impl PyFaultConfigurationIter { /// Complete fault catalog for a circuit and noise model. #[pyclass(name = "FaultCatalog", module = "pecos_rslib_exp")] pub struct PyFaultCatalog { - /// Physical fault locations with nonzero channel probability. + /// Physical fault locations in the structural catalog. #[pyo3(get)] locations: Vec>, /// Rust-side catalog for iterator support. rust_catalog: pecos_qec::fault_tolerance::fault_sampler::FaultCatalog, } -#[pymethods] -impl PyFaultCatalog { - fn __len__(&self) -> usize { - self.locations.len() +fn stochastic_params_from_inputs( + noise: Option<&PyNoiseModelBuilder>, + p1: Option, + p2: Option, + p_meas: Option, + p_prep: Option, +) -> pecos_qec::fault_tolerance::fault_sampler::StochasticNoiseParams { + let mut params = noise.map_or( + pecos_qec::fault_tolerance::fault_sampler::StochasticNoiseParams { + p1: 0.0, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + |noise| pecos_qec::fault_tolerance::fault_sampler::StochasticNoiseParams { + p1: noise.p1, + p2: noise.p2, + p_meas: noise.p_meas, + p_prep: noise.p_prep, + }, + ); + if let Some(p) = p1 { + params.p1 = p; } - - fn __getitem__(&self, py: Python<'_>, index: isize) -> PyResult> { - let len = isize::try_from(self.locations.len()).map_err(|_| { - pyo3::exceptions::PyIndexError::new_err("fault catalog is too large to index") - })?; - let index = if index < 0 { len + index } else { index }; - if index < 0 || index >= len { - return Err(pyo3::exceptions::PyIndexError::new_err( - "fault catalog index out of range", - )); - } - let index = usize::try_from(index).map_err(|_| { - pyo3::exceptions::PyIndexError::new_err("fault catalog index out of range") - })?; - Ok(self.locations[index].clone_ref(py)) + if let Some(p) = p2 { + params.p2 = p; } - - fn __iter__(slf: PyRef<'_, Self>, py: Python<'_>) -> PyResult> { - let locations = pyo3::types::PyList::new(py, slf.locations.iter().map(|loc| loc.bind(py)))?; - Ok(locations.call_method0("__iter__")?.unbind()) + if let Some(p) = p_meas { + params.p_meas = p; } - - /// Lazily iterate all k-fault configurations. - /// - /// Returns an iterator yielding `FaultConfiguration` objects one at a time. - fn fault_configurations( - &self, - py: Python<'_>, - k: usize, - ) -> PyResult> { - use pecos_qec::fault_tolerance::fault_sampler::OwnedFaultConfigIter; - let inner = OwnedFaultConfigIter::new(self.rust_catalog.clone(), k); - let py_locations: Vec> = - self.locations.iter().map(|l| l.clone_ref(py)).collect(); - Py::new( - py, - PyFaultConfigurationIter { - inner, - py_locations, - }, - ) + if let Some(p) = p_prep { + params.p_prep = p; } + params } -/// Build a fault catalog for a circuit and noise model. -/// -/// Returns a ``FaultCatalog`` object with ``catalog.locations``. The catalog -/// also supports direct iteration, indexing, and ``len(catalog)``. -/// -/// Each location has attribute access: ``loc.tick``, ``loc.gate_type``, -/// ``loc.qubits``, ``loc.faults``. -/// -/// Each ``FaultAlternative`` has: ``fault.kind``, ``fault.pauli`` (a real -/// PECOS ``PauliString`` or ``None``), ``fault.detectors``, ``fault.observables``, -/// ``fault.tracked_ops``, ``fault.measurements``, ``fault.conditional_probability``, -/// ``fault.absolute_probability``, ``fault.channel_probability``. -/// -/// Includes all physical locations with nonzero channel probability, even -/// those with no downstream effect (needed for normalization/accounting). -#[pyfunction] -#[pyo3(signature = (tick_circuit, noise))] -pub fn fault_catalog( - tick_circuit: &Bound<'_, PyAny>, - noise: &PyNoiseModelBuilder, +fn py_locations_from_catalog( py: Python<'_>, -) -> PyResult { - use pecos_qec::fault_tolerance::fault_sampler::{ - FaultKind, StochasticNoiseParams, build_fault_catalog, - }; + catalog: &pecos_qec::fault_tolerance::fault_sampler::FaultCatalog, +) -> PyResult>> { + use pecos_qec::fault_tolerance::fault_sampler::{FaultChannel, FaultKind}; - let tc = build_rust_tick_circuit(tick_circuit)?; - let noise_params = StochasticNoiseParams { - p1: noise.p1, - p2: noise.p2, - p_meas: noise.p_meas, - p_prep: noise.p_prep, - }; - - let catalog = build_fault_catalog(&tc, &noise_params) - .map_err(|e| pyo3::exceptions::PyRuntimeError::new_err(e.to_string()))?; - - // Import PauliString and Pauli from pecos.quantum let quantum_mod = py.import("pecos.quantum")?; let ps_class = quantum_mod.getattr("PauliString")?; let pauli_enum = quantum_mod.getattr("Pauli")?; @@ -1601,10 +1555,10 @@ pub fn fault_catalog( gate_type: format!("{:?}", loc.gate_type), qubits: loc.qubits.clone(), channel: match loc.channel { - pecos_qec::fault_tolerance::fault_sampler::FaultChannel::P1 => "p1", - pecos_qec::fault_tolerance::fault_sampler::FaultChannel::P2 => "p2", - pecos_qec::fault_tolerance::fault_sampler::FaultChannel::PMeas => "p_meas", - pecos_qec::fault_tolerance::fault_sampler::FaultChannel::PPrep => "p_prep", + FaultChannel::P1 => "p1", + FaultChannel::P2 => "p2", + FaultChannel::PMeas => "p_meas", + FaultChannel::PPrep => "p_prep", } .to_string(), channel_probability: loc.channel_probability, @@ -1614,9 +1568,169 @@ pub fn fault_catalog( }, )?); } + Ok(locations) +} + +fn sync_py_catalog_probabilities(py: Python<'_>, catalog: &mut PyFaultCatalog) -> PyResult<()> { + if catalog.locations.len() != catalog.rust_catalog.locations.len() { + catalog.locations = py_locations_from_catalog(py, &catalog.rust_catalog)?; + return Ok(()); + } + + let fault_lengths_match = catalog + .locations + .iter() + .zip(&catalog.rust_catalog.locations) + .all(|(py_loc, rust_loc)| py_loc.borrow(py).faults.len() == rust_loc.faults.len()); + if !fault_lengths_match { + catalog.locations = py_locations_from_catalog(py, &catalog.rust_catalog)?; + return Ok(()); + } + + for (py_loc, rust_loc) in catalog + .locations + .iter() + .zip(&catalog.rust_catalog.locations) + { + let mut loc = py_loc.borrow_mut(py); + loc.channel_probability = rust_loc.channel_probability; + loc.no_fault_probability = rust_loc.no_fault_probability; + loc.num_alternatives = rust_loc.num_alternatives; + for (py_fault, rust_fault) in loc.faults.iter().zip(&rust_loc.faults) { + let mut fault = py_fault.borrow_mut(py); + fault.conditional_probability = rust_fault.conditional_probability; + fault.absolute_probability = rust_fault.absolute_probability; + fault.channel_probability = rust_loc.channel_probability; + } + } + Ok(()) +} +fn py_fault_catalog_from_rust( + py: Python<'_>, + catalog: pecos_qec::fault_tolerance::fault_sampler::FaultCatalog, +) -> PyResult { + let locations = py_locations_from_catalog(py, &catalog)?; Ok(PyFaultCatalog { locations, rust_catalog: catalog, }) } + +#[pymethods] +impl PyFaultCatalog { + fn __len__(&self) -> usize { + self.locations.len() + } + + fn __getitem__(&self, py: Python<'_>, index: isize) -> PyResult> { + let len = isize::try_from(self.locations.len()).map_err(|_| { + pyo3::exceptions::PyIndexError::new_err("fault catalog is too large to index") + })?; + let index = if index < 0 { len + index } else { index }; + if index < 0 || index >= len { + return Err(pyo3::exceptions::PyIndexError::new_err( + "fault catalog index out of range", + )); + } + let index = usize::try_from(index).map_err(|_| { + pyo3::exceptions::PyIndexError::new_err("fault catalog index out of range") + })?; + Ok(self.locations[index].clone_ref(py)) + } + + fn __iter__(slf: PyRef<'_, Self>, py: Python<'_>) -> PyResult> { + let locations = pyo3::types::PyList::new(py, slf.locations.iter().map(|loc| loc.bind(py)))?; + Ok(locations.call_method0("__iter__")?.unbind()) + } + + /// Recompute catalog probabilities for a new stochastic noise point. + #[pyo3(signature = (noise=None, *, p1=None, p2=None, p_meas=None, p_prep=None))] + fn with_noise( + &mut self, + py: Python<'_>, + noise: Option<&PyNoiseModelBuilder>, + p1: Option, + p2: Option, + p_meas: Option, + p_prep: Option, + ) -> PyResult<()> { + let params = stochastic_params_from_inputs(noise, p1, p2, p_meas, p_prep); + self.rust_catalog.with_noise(¶ms); + sync_py_catalog_probabilities(py, self) + } + + /// Return a cloned catalog parameterized at a new stochastic noise point. + #[pyo3(signature = (noise=None, *, p1=None, p2=None, p_meas=None, p_prep=None))] + fn parameterized( + &self, + py: Python<'_>, + noise: Option<&PyNoiseModelBuilder>, + p1: Option, + p2: Option, + p_meas: Option, + p_prep: Option, + ) -> PyResult { + let params = stochastic_params_from_inputs(noise, p1, p2, p_meas, p_prep); + py_fault_catalog_from_rust(py, self.rust_catalog.parameterized(¶ms)) + } + + /// Lazily iterate all k-fault configurations. + /// + /// Returns an iterator yielding `FaultConfiguration` objects one at a time. + fn fault_configurations( + &self, + py: Python<'_>, + k: usize, + ) -> PyResult> { + use pecos_qec::fault_tolerance::fault_sampler::OwnedFaultConfigIter; + let inner = OwnedFaultConfigIter::new(self.rust_catalog.clone(), k); + let py_locations: Vec> = + self.locations.iter().map(|l| l.clone_ref(py)).collect(); + Py::new( + py, + PyFaultConfigurationIter { + inner, + py_locations, + }, + ) + } +} + +/// Build a fault catalog for a circuit, optionally parameterized by a noise model. +/// +/// Returns a ``FaultCatalog`` object with ``catalog.locations``. The catalog +/// also supports direct iteration, indexing, and ``len(catalog)``. +/// +/// Each location has attribute access: ``loc.tick``, ``loc.gate_type``, +/// ``loc.qubits``, ``loc.faults``. +/// +/// Each ``FaultAlternative`` has: ``fault.kind``, ``fault.pauli`` (a real +/// PECOS ``PauliString`` or ``None``), ``fault.detectors``, ``fault.observables``, +/// ``fault.tracked_ops``, ``fault.measurements``, ``fault.conditional_probability``, +/// ``fault.absolute_probability``, ``fault.channel_probability``. +/// +/// When noise is omitted, returns a structural catalog with zero probabilities. +/// The catalog includes all structurally supported physical fault locations. +#[pyfunction] +#[pyo3(signature = (tick_circuit, noise=None, *, p1=None, p2=None, p_meas=None, p_prep=None))] +pub fn fault_catalog( + tick_circuit: &Bound<'_, PyAny>, + noise: Option<&PyNoiseModelBuilder>, + py: Python<'_>, + p1: Option, + p2: Option, + p_meas: Option, + p_prep: Option, +) -> PyResult { + use pecos_qec::fault_tolerance::fault_sampler::FaultCatalog; + + let tc = build_rust_tick_circuit(tick_circuit)?; + let mut catalog = FaultCatalog::from_circuit(&tc) + .map_err(|e| pyo3::exceptions::PyRuntimeError::new_err(e.to_string()))?; + if noise.is_some() || p1.is_some() || p2.is_some() || p_meas.is_some() || p_prep.is_some() { + let noise_params = stochastic_params_from_inputs(noise, p1, p2, p_meas, p_prep); + catalog.with_noise(&noise_params); + } + py_fault_catalog_from_rust(py, catalog) +} diff --git a/python/quantum-pecos/tests/qec/test_fault_catalog.py b/python/quantum-pecos/tests/qec/test_fault_catalog.py index 2c513bb1e..97d0ef9b5 100644 --- a/python/quantum-pecos/tests/qec/test_fault_catalog.py +++ b/python/quantum-pecos/tests/qec/test_fault_catalog.py @@ -234,6 +234,58 @@ def test_prep_fault_with_no_effect_included(self): class TestProbabilities: + def test_structural_catalog_without_noise(self): + tc = build_h_mz() + catalog = fault_catalog(tc) + + assert len(catalog.locations) == 2 + assert {loc.channel for loc in catalog.locations} == {"p1", "p_meas"} + assert all(loc.channel_probability == 0.0 for loc in catalog.locations) + assert all(loc.no_fault_probability == 1.0 for loc in catalog.locations) + assert all( + fault.absolute_probability == 0.0 + for loc in catalog.locations + for fault in loc.faults + ) + + def test_with_noise_updates_existing_python_references(self): + tc = build_h_mz() + catalog = fault_catalog(tc) + h_loc = [loc for loc in catalog if loc.channel == "p1"][0] + h_fault = h_loc.faults[0] + mz_loc = [loc for loc in catalog if loc.channel == "p_meas"][0] + + catalog.with_noise(p1=0.06, p_meas=0.02) + + assert abs(h_loc.channel_probability - 0.06) < 1e-12 + assert abs(h_loc.no_fault_probability - 0.94) < 1e-12 + assert abs(h_fault.absolute_probability - 0.02) < 1e-12 + assert abs(h_fault.channel_probability - 0.06) < 1e-12 + assert abs(mz_loc.channel_probability - 0.02) < 1e-12 + assert abs(mz_loc.faults[0].absolute_probability - 0.02) < 1e-12 + + def test_parameterized_returns_independent_catalog(self): + tc = build_h_mz() + catalog = fault_catalog(tc, p1=0.03, p_meas=0.01) + clone = catalog.parameterized(p1=0.09, p_meas=0.04) + + original_h = [loc for loc in catalog if loc.channel == "p1"][0] + clone_h = [loc for loc in clone if loc.channel == "p1"][0] + assert abs(original_h.channel_probability - 0.03) < 1e-12 + assert abs(clone_h.channel_probability - 0.09) < 1e-12 + assert original_h is not clone_h + + def test_sparse_channel_keeps_zero_probability_structure(self): + tc = build_h_mz() + catalog = fault_catalog(tc, p1=0.0, p_meas=0.02) + + h_loc = [loc for loc in catalog if loc.channel == "p1"][0] + mz_loc = [loc for loc in catalog if loc.channel == "p_meas"][0] + assert h_loc.channel_probability == 0.0 + assert all(f.absolute_probability == 0.0 for f in h_loc.faults) + assert abs(mz_loc.channel_probability - 0.02) < 1e-12 + assert abs(mz_loc.faults[0].absolute_probability - 0.02) < 1e-12 + def test_single_qubit_location_fields(self): tc = build_h_mz() noise = depolarizing().p1(0.03).p2(0).p_meas(0).p_prep(0) @@ -341,6 +393,59 @@ def test_k1_exposes_single_fault(self): assert c.alternative_indices == [0] assert c.selected_probability > 0 + def test_k1_skips_zero_probability_structural_locations(self): + tc = build_h_mz() + catalog = fault_catalog(tc, p1=0.03, p_meas=0.0) + + assert len(catalog.locations) == 2 + h_idx = next(i for i, loc in enumerate(catalog) if loc.gate_type == "H") + mz_idx = next(i for i, loc in enumerate(catalog) if loc.gate_type == "MZ") + assert catalog.locations[mz_idx].channel_probability == 0.0 + + configs = list(catalog.fault_configurations(1)) + assert len(configs) == 3 + assert all(c.location_indices == [h_idx] for c in configs) + assert all(c.selected_probability > 0 for c in configs) + assert all(mz_idx not in c.location_indices for c in configs) + assert list(catalog.fault_configurations(2)) == [] + + def test_all_zero_noise_only_yields_k0(self): + tc = build_h_mz() + catalog = fault_catalog(tc, p1=0.0, p_meas=0.0) + + k0 = list(catalog.fault_configurations(0)) + assert len(k0) == 1 + assert k0[0].configuration_probability == 1.0 + assert list(catalog.fault_configurations(1)) == [] + + def test_nonzero_silent_faults_are_yielded(self): + tc = TickCircuit() + tc.tick().h([0]) + tc.set_meta("num_measurements", "0") + tc.set_meta("detectors", "[]") + tc.set_meta("observables", "[]") + + catalog = fault_catalog(tc, p1=0.03, p_meas=0.0) + configs = list(catalog.fault_configurations(1)) + + assert len(configs) == 3 + assert all(c.measurements == [] for c in configs) + assert all(c.detectors == [] for c in configs) + assert all(c.observables == [] for c in configs) + assert all(c.selected_probability > 0 for c in configs) + + def test_with_noise_zeroes_channel_for_new_iterators(self): + tc = build_h_mz() + catalog = fault_catalog(tc, p1=0.03, p_meas=0.01) + + catalog.with_noise(p1=0.0, p_meas=0.02) + + mz_idx = next(i for i, loc in enumerate(catalog) if loc.gate_type == "MZ") + configs = list(catalog.fault_configurations(1)) + assert len(configs) == 1 + assert configs[0].location_indices == [mz_idx] + assert configs[0].selected_probability == pytest.approx(0.02) + def test_k2_xor_cancels_effects(self): """Two faults flipping the same detector XOR-cancel.""" tc = TickCircuit() diff --git a/python/quantum-pecos/tests/qec/test_traced_qis_clifford_pipeline.py b/python/quantum-pecos/tests/qec/test_traced_qis_clifford_pipeline.py index ecb61c6cf..c565f619f 100644 --- a/python/quantum-pecos/tests/qec/test_traced_qis_clifford_pipeline.py +++ b/python/quantum-pecos/tests/qec/test_traced_qis_clifford_pipeline.py @@ -222,7 +222,12 @@ def test_explicit_python_gate_names_map_to_rust_clifford_gates(): assert result.num_measurements == 2 catalog = fault_catalog(tc, noise) - assert sum(len(loc.faults) for loc in catalog) == 156 + # Structural catalog includes all locations (including p_meas=0 and p_prep=0). + # Count only alternatives at locations with nonzero channel probability. + nonzero_alts = sum( + len(loc.faults) for loc in catalog if loc.channel_probability > 0.0 + ) + assert nonzero_alts == 156 def test_sim_neo_native_backends_accept_face_gates(): From 89424c6f235ef753c36e05330921e606b49c4158 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 07:12:47 -0600 Subject: [PATCH 058/125] Ruff config expansion and lint fixes across codebase --- crates/pecos-chromobius/build_chromobius.rs | 19 +- crates/pecos-engines/src/noise/general.rs | 7 + .../tests/influence_sampler_audit.rs | 5 +- .../fault_tolerance/dem_builder/builder.rs | 10 +- .../src/fault_tolerance/fault_sampler.rs | 50 ++-- .../targeted_lookup_decoder.rs | 4 +- .../src/clifford_matrix_oracle.rs | 6 +- .../examples/profile_decode.rs | 18 +- crates/pecos-uf-decoder/src/decoder.rs | 2 +- crates/pecos-uf-decoder/src/windowed.rs | 4 +- docs/concepts/decoder-architecture.md | 9 +- docs/user-guide/fault-catalog.md | 4 +- examples/surface/brickwork_sweep.py | 58 +++-- examples/surface/build_report.py | 7 +- examples/surface/coherent_noise_sweep.py | 23 +- examples/surface/d3_fault_catalog_lookup.rs | 46 ++-- examples/surface/dem_comparison.py | 8 +- examples/surface/dem_method_ler_comparison.py | 132 ++++++---- examples/surface/dem_tutorial.py | 15 +- examples/surface/dem_vs_stabilizer.py | 11 +- examples/surface/eeg_formula_comparison.py | 18 +- examples/surface/eeg_vs_statevec.py | 33 ++- examples/surface/ml_lookup_decoder.py | 51 +++- examples/surface/validate_dem_correlations.py | 126 +++++---- examples/surface/validate_dem_generators.py | 236 +++++++++-------- exp/pecos-eeg/examples/profile_heisenberg.rs | 11 +- exp/pecos-eeg/src/circuit.rs | 4 +- exp/pecos-eeg/src/dem_mapping.rs | 12 +- exp/pecos-eeg/src/heisenberg.rs | 14 +- exp/pecos-eeg/src/stabilizer.rs | 4 +- exp/pecos-eeg/src/strong_sim.rs | 9 +- exp/pecos-eeg/tests/beta_investigation.rs | 17 +- exp/pecos-eeg/tests/generator_trace.rs | 48 ++-- exp/pecos-eeg/tests/stabilizer_audit.rs | 30 +-- exp/pecos-eeg/tests/statevec_comparison.rs | 241 +++++++++--------- exp/pecos-eeg/tests/strong_sim_validation.rs | 2 +- exp/pecos-neo/src/runner.rs | 5 +- .../quantum-pecos/src/pecos/qec/analysis.py | 126 +++------ .../src/pecos/qec/surface/circuit_builder.py | 11 +- .../src/pecos/qec/surface/decode.py | 4 +- .../src/pecos/qec/surface/logical_circuit.py | 97 ++++--- python/quantum-pecos/tests/docs/conftest.py | 2 +- .../tests/pecos/test_selene_sim_parity.py | 15 +- .../tests/qec/surface/test_circuit_fuzz.py | 71 ++++-- .../qec/surface/test_surface_geometry.py | 40 +-- .../tests/qec/test_analysis_meas_sampling.py | 58 +++-- .../tests/qec/test_dem_sampler.py | 18 +- .../tests/qec/test_dem_sampler_vs_stim.py | 2 +- .../tests/qec/test_fault_catalog.py | 54 ++-- .../tests/qec/test_meas_sampling_backend.py | 29 +-- .../qec/test_meas_sampling_generality.py | 49 ++-- .../tests/qec/test_raw_measurement_result.py | 3 +- .../tests/qec/test_sample_batch.py | 20 +- .../qec/test_traced_qis_clifford_pipeline.py | 4 +- .../qec/test_traced_qis_slow_integration.py | 1 - ruff.toml | 28 +- scripts/bench_raw_meas_sampling.py | 15 +- scripts/compare_meas_sampling_pipeline.py | 30 ++- 58 files changed, 1076 insertions(+), 900 deletions(-) diff --git a/crates/pecos-chromobius/build_chromobius.rs b/crates/pecos-chromobius/build_chromobius.rs index 108c6cfdc..dd2d0bf94 100644 --- a/crates/pecos-chromobius/build_chromobius.rs +++ b/crates/pecos-chromobius/build_chromobius.rs @@ -62,18 +62,27 @@ pub fn build() -> Result<()> { // PyMatching headers and compiled objects come from pecos-pymatching via cargo metadata. // This avoids compiling a second copy of PyMatching sources which would cause // duplicate symbol errors at link time. - let pymatching_include = env::var("DEP_PYMATCHING_PECOS_PYMATCHING_INCLUDE").map_or_else(|_| { + let pymatching_include = env::var("DEP_PYMATCHING_PECOS_PYMATCHING_INCLUDE").map_or_else( + |_| { // Fallback: download and use directly (for standalone builds) ensure_dep_ready("pymatching", &manifest) .expect("pymatching dependency") .join("src") - }, PathBuf::from); - let stim_include = env::var("DEP_PYMATCHING_PECOS_STIM_INCLUDE").map_or_else(|_| { + }, + PathBuf::from, + ); + let stim_include = env::var("DEP_PYMATCHING_PECOS_STIM_INCLUDE").map_or_else( + |_| { ensure_dep_ready("stim", &manifest) .expect("stim dependency") .join("src") - }, PathBuf::from); - let stim_dir_for_header = env::var("DEP_PYMATCHING_PECOS_STIM_DIR").map_or_else(|_| ensure_dep_ready("stim", &manifest).expect("stim dependency"), PathBuf::from); + }, + PathBuf::from, + ); + let stim_dir_for_header = env::var("DEP_PYMATCHING_PECOS_STIM_DIR").map_or_else( + |_| ensure_dep_ready("stim", &manifest).expect("stim dependency"), + PathBuf::from, + ); let pymatching_lib_dir = env::var("DEP_PYMATCHING_PECOS_LIB_DIR") .ok() .map(PathBuf::from); diff --git a/crates/pecos-engines/src/noise/general.rs b/crates/pecos-engines/src/noise/general.rs index 28bf37574..b3404751d 100644 --- a/crates/pecos-engines/src/noise/general.rs +++ b/crates/pecos-engines/src/noise/general.rs @@ -1559,6 +1559,7 @@ mod tests { angles: vec![].into(), qubits: vec![QubitId(qubit)].into(), params: vec![].into(), + meas_ids: vec![].into(), }); } let measurement_request = request_builder.build(); @@ -1640,6 +1641,7 @@ mod tests { angles: vec![].into(), qubits: vec![QubitId(0)].into(), params: vec![].into(), + meas_ids: vec![].into(), }; // Create a builder and apply noise @@ -1829,6 +1831,7 @@ mod tests { angles: vec![].into(), qubits: vec![QubitId(0)].into(), params: vec![].into(), + meas_ids: vec![].into(), }; noise.apply_prep_faults(&prep_gate, &mut builder); @@ -2746,6 +2749,7 @@ mod tests { angles: vec![].into(), qubits: vec![QubitId(0)].into(), params: vec![1.0].into(), // 1 second duration + meas_ids: vec![].into(), }; // Apply idle faults - should use coherent dephasing (RZ gates) @@ -2769,6 +2773,7 @@ mod tests { angles: vec![].into(), qubits: vec![QubitId(0), QubitId(1), QubitId(2)].into(), // 3 qubits params: vec![1.0].into(), // 1 second duration + meas_ids: vec![].into(), }; model.apply_idle_faults( @@ -2905,6 +2910,7 @@ mod tests { angles: vec![Angle64::from_radians(0.1)].into(), qubits: vec![QubitId(0)].into(), params: vec![].into(), + meas_ids: vec![].into(), }; // Create an X gate (not noiseless - should have noise applied) @@ -2913,6 +2919,7 @@ mod tests { angles: vec![].into(), qubits: vec![QubitId(0)].into(), params: vec![].into(), + meas_ids: vec![].into(), }; // Make sure RZ is recognized as noiseless diff --git a/crates/pecos-gpu-sims/tests/influence_sampler_audit.rs b/crates/pecos-gpu-sims/tests/influence_sampler_audit.rs index 6c6d2e0c5..0db043ac9 100644 --- a/crates/pecos-gpu-sims/tests/influence_sampler_audit.rs +++ b/crates/pecos-gpu-sims/tests/influence_sampler_audit.rs @@ -210,10 +210,7 @@ fn determinism_with_same_seed() { }; let ra = a.sample_uniform(64, 0.1); let rb = b.sample_uniform(64, 0.1); - assert_eq!( - ra.count_logical_errors(), - rb.count_logical_errors() - ); + assert_eq!(ra.count_logical_errors(), rb.count_logical_errors()); for shot in 0..64 { assert_eq!( ra.has_logical_error(shot), diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs index c074e1afb..a53e7c658 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs @@ -1607,10 +1607,12 @@ mod tests { if location.num_alternatives == 0 { continue; } - let per_channel_probability = 1.0 - - location - .no_fault_probability - .powf(1.0 / location.num_alternatives as f64); + let num_alternatives = f64::from( + u32::try_from(location.num_alternatives) + .expect("fault alternative count fits in u32"), + ); + let per_channel_probability = + 1.0 - location.no_fault_probability.powf(1.0 / num_alternatives); for fault in &location.faults { if fault.affected_detectors.is_empty() && fault.affected_observables.is_empty() { diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index 5420aef5c..da43794f8 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -1822,7 +1822,14 @@ impl RawMeasurementPlan { mod tests { use super::*; - /// Build a minimal TickCircuit: PZ(0) H(0) CX(0,1) H(0) MZ(0) PZ(0) H(0) CX(0,1) H(0) MZ(0) + fn assert_close(actual: f64, expected: f64) { + assert!( + (actual - expected).abs() < 1e-12, + "expected {expected}, got {actual}" + ); + } + + /// Build a minimal `TickCircuit`: PZ(0) H(0) CX(0,1) H(0) MZ(0) PZ(0) H(0) CX(0,1) H(0) MZ(0) fn two_round_x_check() -> TickCircuit { let mut tc = TickCircuit::new(); // Round 1 @@ -1893,8 +1900,7 @@ mod tests { for alt in &m.alternatives { assert!( !(alt.contains(&0) && alt.contains(&1)), - "Fault alternative crosses PZ boundary: {:?}", - alt + "Fault alternative crosses PZ boundary: {alt:?}" ); } } @@ -2721,20 +2727,20 @@ mod tests { catalog .locations .iter() - .all(|loc| loc.channel_probability == 0.0) + .all(|loc| loc.channel_probability.abs() < 1e-12) ); assert!( catalog .locations .iter() - .all(|loc| loc.no_fault_probability == 1.0) + .all(|loc| (loc.no_fault_probability - 1.0).abs() < 1e-12) ); assert!( catalog .locations .iter() .flat_map(|loc| &loc.faults) - .all(|fault| fault.absolute_probability == 0.0) + .all(|fault| fault.absolute_probability.abs() < 1e-12) ); assert!( catalog @@ -2786,8 +2792,8 @@ mod tests { assert_eq!(a.gate_type, b.gate_type); assert_eq!(a.qubits, b.qubits); assert_eq!(a.channel, b.channel); - assert_eq!(a.channel_probability, b.channel_probability); - assert_eq!(a.no_fault_probability, b.no_fault_probability); + assert_close(a.channel_probability, b.channel_probability); + assert_close(a.no_fault_probability, b.no_fault_probability); assert_eq!(a.num_alternatives, b.num_alternatives); assert_eq!(a.faults.len(), b.faults.len()); for (af, bf) in a.faults.iter().zip(&b.faults) { @@ -2797,8 +2803,8 @@ mod tests { assert_eq!(af.affected_detectors, bf.affected_detectors); assert_eq!(af.affected_observables, bf.affected_observables); assert_eq!(af.affected_tracked_ops, bf.affected_tracked_ops); - assert_eq!(af.conditional_probability, bf.conditional_probability); - assert_eq!(af.absolute_probability, bf.absolute_probability); + assert_close(af.conditional_probability, bf.conditional_probability); + assert_close(af.absolute_probability, bf.absolute_probability); } } } @@ -2832,8 +2838,8 @@ mod tests { .iter() .find(|loc| loc.channel == FaultChannel::P1) .unwrap(); - assert_eq!(h_loc.channel_probability, 0.09); - assert_eq!(h_loc.no_fault_probability, 0.91); + assert_close(h_loc.channel_probability, 0.09); + assert_close(h_loc.no_fault_probability, 0.91); assert!( h_loc .faults @@ -2846,8 +2852,8 @@ mod tests { .iter() .find(|loc| loc.channel == FaultChannel::PMeas) .unwrap(); - assert_eq!(meas_loc.channel_probability, 0.02); - assert_eq!(meas_loc.faults[0].absolute_probability, 0.02); + assert_close(meas_loc.channel_probability, 0.02); + assert_close(meas_loc.faults[0].absolute_probability, 0.02); } #[test] @@ -2872,12 +2878,12 @@ mod tests { catalog .locations .iter() - .any(|loc| loc.channel == FaultChannel::P1 && loc.channel_probability == 0.0) + .any(|loc| loc.channel == FaultChannel::P1 && loc.channel_probability.abs() < 1e-12) ); let mechanisms = catalog.to_mechanisms(); assert_eq!(mechanisms.len(), 1); - assert_eq!(mechanisms[0].probability, 0.02); + assert_close(mechanisms[0].probability, 0.02); assert_eq!(mechanisms[0].alternatives, vec![vec![0]]); assert_eq!(mechanisms, build_fault_table(&tc, &noise).unwrap()); } @@ -2950,7 +2956,7 @@ mod tests { "mechanism count must match" ); for (old, new) in old_mechanisms.iter().zip(&new_mechanisms) { - assert_eq!(old.probability, new.probability, "probability must match"); + assert_close(old.probability, new.probability); assert_eq!( old.alternatives.len(), new.alternatives.len(), @@ -3121,7 +3127,7 @@ mod tests { assert!(c.alternative_indices.is_empty()); assert!(c.affected_measurements.is_empty()); assert!(c.affected_detectors.is_empty()); - assert_eq!(c.selected_probability, 1.0); + assert_close(c.selected_probability, 1.0); // config_prob = product of all no_fault_probability let expected: f64 = catalog .locations @@ -3196,7 +3202,7 @@ mod tests { .iter() .position(|loc| loc.gate_type == GateType::MZ) .unwrap(); - assert_eq!(catalog.locations[mz_idx].channel_probability, 0.0); + assert_close(catalog.locations[mz_idx].channel_probability, 0.0); let configs: Vec<_> = catalog.fault_configurations(1).collect(); assert_eq!(configs.len(), 3); @@ -3235,7 +3241,7 @@ mod tests { let k0: Vec<_> = catalog.fault_configurations(0).collect(); assert_eq!(k0.len(), 1); - assert_eq!(k0[0].configuration_probability, 1.0); + assert_close(k0[0].configuration_probability, 1.0); assert_eq!(catalog.fault_configurations(1).count(), 0); assert_eq!(catalog.fault_configurations(2).count(), 0); } @@ -3304,7 +3310,7 @@ mod tests { let configs: Vec<_> = catalog.fault_configurations(1).collect(); assert_eq!(configs.len(), 1); assert_eq!(configs[0].location_indices, vec![mz_idx]); - assert_eq!(configs[0].selected_probability, 0.02); + assert_close(configs[0].selected_probability, 0.02); } #[test] @@ -3510,7 +3516,7 @@ mod tests { // base=0, fault flips with prob 2/3 → mean should be ~2/3. let ones: usize = (0..9000).filter(|&s| result.get(s, 0).0).count(); - let mean = ones as f64 / 9000.0; + let mean = f64::from(u32::try_from(ones).expect("sample count fits in u32")) / 9000.0; assert!( (mean - 2.0 / 3.0).abs() < 0.03, "Expected ~2/3 flip rate from grouped alternatives, got {mean:.4}" diff --git a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs index e364c1cfc..0df2b2e70 100644 --- a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs +++ b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs @@ -320,7 +320,7 @@ mod tests { build_fault_catalog(&tc, &noise).unwrap() } - /// Brute-force reference: enumerate all configurations up to max_faults, + /// Brute-force reference: enumerate all configurations up to `max_faults`, /// accumulate odds weights by (syndrome, logical). fn brute_force_weights( catalog: &FaultCatalog, @@ -365,7 +365,7 @@ mod tests { let empty = decoder.decode(&[]); assert_eq!(empty.logical_weights.len(), 1); - assert_eq!(empty.logical_weights[&vec![]], 1.0); + assert!((empty.logical_weights[&vec![]] - 1.0).abs() < 1e-12); let non_empty = decoder.decode(&[0]); assert!( diff --git a/crates/pecos-simulators/src/clifford_matrix_oracle.rs b/crates/pecos-simulators/src/clifford_matrix_oracle.rs index 9d17c60ba..b008b98f2 100644 --- a/crates/pecos-simulators/src/clifford_matrix_oracle.rs +++ b/crates/pecos-simulators/src/clifford_matrix_oracle.rs @@ -4,7 +4,10 @@ use num_complex::Complex64; use std::f64::consts::FRAC_1_SQRT_2; +const MATRIX_EPS: f64 = 1e-9; + #[derive(Clone, Copy, Debug)] +#[allow(clippy::upper_case_acronyms)] pub(crate) enum CliffordMatrixGate { SZdg, F, @@ -109,11 +112,10 @@ impl Matrix { fn approx_eq(&self, other: &Self) -> bool { assert_eq!(self.n, other.n); - const EPS: f64 = 1e-9; self.data .iter() .zip(other.data.iter()) - .all(|(a, b)| (*a - *b).norm() < EPS) + .all(|(a, b)| (*a - *b).norm() < MATRIX_EPS) } } diff --git a/crates/pecos-uf-decoder/examples/profile_decode.rs b/crates/pecos-uf-decoder/examples/profile_decode.rs index c5077367a..78bcd54fa 100644 --- a/crates/pecos-uf-decoder/examples/profile_decode.rs +++ b/crates/pecos-uf-decoder/examples/profile_decode.rs @@ -10,6 +10,10 @@ const D3_DEM: &str = const D5_DEM: &str = include_str!("../../../examples/surface_code_circuits/surface_code_d5_z_stim.dem"); +fn shots_as_f64(num_shots: usize) -> f64 { + f64::from(u32::try_from(num_shots).expect("profile shot count fits in u32")) +} + fn profile_decoder(name: &str, dem: &str, num_shots: usize) { let graph = DemMatchingGraph::from_dem_str(dem).unwrap(); let mut dec = UfDecoder::from_matching_graph(&graph, UfDecoderConfig::fast()); @@ -35,8 +39,9 @@ fn profile_decoder(name: &str, dem: &str, num_shots: usize) { } let elapsed = t0.elapsed(); - let per_shot_ns = elapsed.as_nanos() as f64 / num_shots as f64; - let throughput = num_shots as f64 / elapsed.as_secs_f64(); + let shots = shots_as_f64(num_shots); + let per_shot_ns = elapsed.as_secs_f64() * 1.0e9 / shots; + let throughput = shots / elapsed.as_secs_f64(); println!( "{name:8}: {num_det:3} det, {per_shot_ns:8.0} ns/shot ({:.0} kshots/s), errors={errors}", throughput / 1000.0 @@ -68,8 +73,9 @@ fn profile_phases(name: &str, dem: &str, num_shots: usize) { } let total_time = t0.elapsed(); - let grow_ns = grow_time.as_nanos() as f64 / num_shots as f64; - let total_ns = total_time.as_nanos() as f64 / num_shots as f64; + let shots = shots_as_f64(num_shots); + let grow_ns = grow_time.as_secs_f64() * 1.0e9 / shots; + let total_ns = total_time.as_secs_f64() * 1.0e9 / shots; let peel_ns = total_ns - grow_ns; println!( @@ -88,7 +94,7 @@ fn profile_phases(name: &str, dem: &str, num_shots: usize) { let _ = bp_dec.decode_to_observables(syn); } let bp_total = t0.elapsed(); - let bp_ns = bp_total.as_nanos() as f64 / num_shots as f64; + let bp_ns = bp_total.as_secs_f64() * 1.0e9 / shots; let bp_only = bp_ns - total_ns; // approximate BP overhead println!( " BP+UF: {bp_ns:.0} ns/shot total (BP overhead ~{bp_only:.0} ns = {:.0}%)", @@ -133,6 +139,6 @@ fn main() { let _ = dec.decode_syndrome(syn); } let elapsed = t0.elapsed(); - let per_shot_ns = elapsed.as_nanos() as f64 / num_shots as f64; + let per_shot_ns = elapsed.as_secs_f64() * 1.0e9 / shots_as_f64(num_shots); println!("d5-bal : {num_det:3} det, {per_shot_ns:8.0} ns/shot"); } diff --git a/crates/pecos-uf-decoder/src/decoder.rs b/crates/pecos-uf-decoder/src/decoder.rs index 366789c0a..1ce43de0d 100644 --- a/crates/pecos-uf-decoder/src/decoder.rs +++ b/crates/pecos-uf-decoder/src/decoder.rs @@ -25,9 +25,9 @@ //! //! All data structures are flat arrays. Zero per-shot allocation after init. +use pecos_decoder_core::correlated_decoder::MatchingDecoder; use pecos_decoder_core::dem::DemMatchingGraph; use pecos_decoder_core::errors::DecoderError; -use pecos_decoder_core::correlated_decoder::MatchingDecoder; use std::cmp::Reverse; use std::collections::BinaryHeap; diff --git a/crates/pecos-uf-decoder/src/windowed.rs b/crates/pecos-uf-decoder/src/windowed.rs index b8b97141d..8864adaf8 100644 --- a/crates/pecos-uf-decoder/src/windowed.rs +++ b/crates/pecos-uf-decoder/src/windowed.rs @@ -535,7 +535,9 @@ fn parse_dem_params( } let num_rounds = (max_time + 1.0) as usize; - let num_stab = num_detectors.checked_div(num_rounds).unwrap_or(num_detectors); + let num_stab = num_detectors + .checked_div(num_rounds) + .unwrap_or(num_detectors); let d_est = ((num_stab as f64).sqrt().ceil() as usize).max(3); let step_size = if config.step_size > 0 { config.step_size diff --git a/docs/concepts/decoder-architecture.md b/docs/concepts/decoder-architecture.md index b54edd498..46f6b94f9 100644 --- a/docs/concepts/decoder-architecture.md +++ b/docs/concepts/decoder-architecture.md @@ -58,8 +58,8 @@ Use `decoder_dem_requirement(decoder_type)` to query what a decoder needs: ```python from pecos_rslib.qec import decoder_dem_requirement -decoder_dem_requirement("pymatching") # "graphlike" -decoder_dem_requirement("tesseract") # "any" +decoder_dem_requirement("pymatching") # "graphlike" +decoder_dem_requirement("tesseract") # "any" ``` ## Layer 2: Observable Subgraph Decoder (OSD) @@ -155,9 +155,10 @@ The `WindowedOsdDecoder` implements windowed OSD: from pecos_rslib.qec import WindowedOsdDecoder decoder = WindowedOsdDecoder( - dem_string, stab_coords, + dem_string, + stab_coords, inner_decoder="pymatching", - step=8, # core window size in time steps + step=8, # core window size in time steps buffer=4, # buffer on each side ) ``` diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index 40ab77e81..08eee9c18 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -245,9 +245,11 @@ For a truncated table: ```python from collections import defaultdict + def add_weight(table, syndrome, logical, probability): table[tuple(syndrome)][tuple(logical)] += probability + table = defaultdict(lambda: defaultdict(float)) for k in range(0, 3): @@ -278,6 +280,7 @@ def xor_sorted(a, b): out.add(item) return tuple(sorted(out)) + for event in catalog.fault_configurations(1): correction = decoder[tuple(event.detectors)] residual = xor_sorted(event.observables, correction) @@ -385,4 +388,3 @@ Run it from the repository root: ```bash cargo run -p pecos-qec --example surface_d3_fault_catalog_lookup ``` - diff --git a/examples/surface/brickwork_sweep.py b/examples/surface/brickwork_sweep.py index db23d9226..88fe9f01e 100644 --- a/examples/surface/brickwork_sweep.py +++ b/examples/surface/brickwork_sweep.py @@ -95,7 +95,7 @@ def build_mirrored_brickwork(width, depth, seed, patch, rounds=2): b.add_transversal_h(label) eff[label] = "X" if eff[label] == "Z" else "Z" layer_ops.append(("H", label)) - b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + b.add_memory(labels, rounds, basis={label: eff[label] for label in labels}) offset = layer % 2 cx_applied = [] @@ -105,7 +105,7 @@ def build_mirrored_brickwork(width, depth, seed, patch, rounds=2): b.add_transversal_cx(ctrl, tgt) cx_applied.append((ctrl, tgt)) if cx_applied: - b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + b.add_memory(labels, rounds, basis={label: eff[label] for label in labels}) layer_ops.append(("CX", cx_applied)) ops_forward.append(layer_ops) @@ -116,18 +116,18 @@ def build_mirrored_brickwork(width, depth, seed, patch, rounds=2): for ctrl, tgt in reversed(args[0]): if eff[ctrl] == eff[tgt]: b.add_transversal_cx(ctrl, tgt) - b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + b.add_memory(labels, rounds, basis={label: eff[label] for label in labels}) for op_type, *args in reversed(layer_ops): if op_type == "H": label = args[0] b.add_transversal_h(label) eff[label] = "X" if eff[label] == "Z" else "Z" - b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + b.add_memory(labels, rounds, basis={label: eff[label] for label in labels}) return b -def build_t_injection_circuit(distance, seed, patch, rounds_per_layer): +def build_t_injection_circuit(distance, _seed, patch, rounds_per_layer): """Build a T-gate injection circuit: memory + T injection + memory.""" from pecos.qec.surface import LogicalCircuitBuilder @@ -256,7 +256,7 @@ def run_sweep( num_errors=errors, logical_error_rate=ler, decode_seconds=dec_sec, - ) + ), ) shard.points.append(point) @@ -387,7 +387,7 @@ def write_html_report(shard: BrickworkShard, path: Path, coherent_results=None) meta_cards = [] if distances: meta_cards.append( - f'
Distances{", ".join(str(d) for d in distances)}
' + f'
Distances{", ".join(str(d) for d in distances)}
', ) if decoders_used: meta_cards.append(f'
Decoders{len(decoders_used)}
') @@ -428,7 +428,7 @@ def write_html_report(shard: BrickworkShard, path: Path, coherent_results=None) "effectively unlimited.

", "", "

Budget strategies

", - "

The decoder framework selects a strategy based on the user-specified reaction " "time budget:

", + "

The decoder framework selects a strategy based on the user-specified reaction time budget:

", "
    ", "
  • unlimited — Full-circuit OSD. Maximum accuracy. " "Appropriate for Clifford circuits or offline analysis.
    • ", @@ -471,7 +471,7 @@ def write_html_report(shard: BrickworkShard, path: Path, coherent_results=None) html_parts.append("

    Brickwork Circuits (Clifford)

    ") html_parts.append( "

    Mirrored random gate sequences (identity operation). " - "LER from stochastic depolarizing noise only.

    " + "LER from stochastic depolarizing noise only.

    ", ) for (d, p), points in sorted(brickwork_tables.items()): @@ -479,8 +479,7 @@ def write_html_report(shard: BrickworkShard, path: Path, coherent_results=None) decoders = sorted({r.decoder for pt in points for r in pt.decoder_results}) html_parts.append("") - for dec in decoders: - html_parts.append(f"") + html_parts.extend(f"" for dec in decoders) html_parts.append("") for pt in sorted(points, key=lambda x: (x.width, x.depth)): @@ -490,7 +489,7 @@ def write_html_report(shard: BrickworkShard, path: Path, coherent_results=None) if r: cls = "good" if r.logical_error_rate < 0.01 else "warn" if r.logical_error_rate < 0.05 else "bad" html_parts.append( - f'", + f'', ) else: html_parts.append("") @@ -506,15 +505,14 @@ def write_html_report(shard: BrickworkShard, path: Path, coherent_results=None) html_parts.append( "

    T gate via magic state teleportation: " "|T⟩ ancilla + CX + measure + conditional S. " - "Feed-forward decision point for the decoder.

    " + "Feed-forward decision point for the decoder.

    ", ) for (d, p), points in sorted(t_injection_tables.items()): decoders = sorted({r.decoder for pt in points for r in pt.decoder_results}) html_parts.append(f"

    d={d}, p={p}

    ") html_parts.append("
    WidthDepth{dec}{dec}
    {r.logical_error_rate:.5f} ' f"({r.decode_seconds:.2f}s){r.logical_error_rate:.5f} ({r.decode_seconds:.2f}s)-
    ") - for dec in decoders: - html_parts.append(f"") + html_parts.extend(f"" for dec in decoders) html_parts.append("") for pt in points: @@ -524,7 +522,7 @@ def write_html_report(shard: BrickworkShard, path: Path, coherent_results=None) if r: cls = "good" if r.logical_error_rate < 0.01 else "warn" if r.logical_error_rate < 0.05 else "bad" html_parts.append( - f'", + f'', ) else: html_parts.append("") @@ -543,7 +541,7 @@ def write_html_report(shard: BrickworkShard, path: Path, coherent_results=None) "uncompensated phase accumulation during idle time. Unlike stochastic " "Z errors, coherent rotations accumulate constructively — the LER " "far exceeds the Pauli-twirled equivalent sin²(θ/2). " - "Decoder uses a stochastic-only DEM. Simulated with StateVec.

    " + "Decoder uses a stochastic-only DEM. Simulated with StateVec.

    ", ) for (d, p), result in sorted(coherent_results.items()): @@ -556,7 +554,7 @@ def write_html_report(shard: BrickworkShard, path: Path, coherent_results=None) "" "" "" - "" + "", ) for pt in result.points: cls = "good" if pt.ler < 0.02 else "warn" if pt.ler < 0.05 else "bad" @@ -589,7 +587,9 @@ def main(): parser.add_argument("--widths", type=int, nargs="+", default=[2, 3, 4]) parser.add_argument("--depths", type=int, nargs="+", default=[1, 2, 3]) parser.add_argument( - "--scaled-depth", action="store_true", help="Override --depths: set depth=2^((d+1)/2) per distance" + "--scaled-depth", + action="store_true", + help="Override --depths: set depth=2^((d+1)/2) per distance", ) parser.add_argument("--error-rates", type=float, nargs="+", default=[0.001]) parser.add_argument("--decoders", nargs="+", default=["observable_subgraph:pymatching"]) @@ -597,13 +597,19 @@ def main(): parser.add_argument("--seed", type=int, default=42) parser.add_argument("--rounds-per-layer", type=int, default=2) parser.add_argument( - "--include-t-injection", action="store_true", help="Include T-gate injection circuits (non-Clifford)" + "--include-t-injection", + action="store_true", + help="Include T-gate injection circuits (non-Clifford)", ) parser.add_argument( - "--t-injection-only", action="store_true", help="Only T-gate injection circuits (skip brickwork)" + "--t-injection-only", + action="store_true", + help="Only T-gate injection circuits (skip brickwork)", ) parser.add_argument( - "--include-coherent-noise", action="store_true", help="Include coherent idle noise sweep (RZ after CX)" + "--include-coherent-noise", + action="store_true", + help="Include coherent idle noise sweep (RZ after CX)", ) parser.add_argument( "--coherent-p-idle", @@ -633,10 +639,10 @@ def main(): # Per-distance depth: 2^((d+1)/2) — challenges the decoder proportionally # d=3→4, d=5→8, d=7→16, d=9→32 depths = [int(2 ** ((d + 1) / 2)) for d in args.distances] - print(f"Scaled depths: {dict(zip(args.distances, depths))}") + print(f"Scaled depths: {dict(zip(args.distances, depths, strict=False))}") all_points = [] - for d, depth in zip(args.distances, depths): + for d, depth in zip(args.distances, depths, strict=False): partial = run_sweep( distances=[d], widths=args.widths, @@ -652,7 +658,7 @@ def main(): config={ "distances": args.distances, "widths": args.widths, - "scaled_depths": dict(zip(args.distances, depths)), + "scaled_depths": dict(zip(args.distances, depths, strict=False)), "error_rates": args.error_rates, "decoders": args.decoders, "shots": args.shots, @@ -737,7 +743,7 @@ def main(): num_errors=errors, logical_error_rate=ler, decode_seconds=dec_sec, - ) + ), ) shard.points.append(point) diff --git a/examples/surface/build_report.py b/examples/surface/build_report.py index bfd9ce43c..ea392b7b6 100644 --- a/examples/surface/build_report.py +++ b/examples/surface/build_report.py @@ -178,7 +178,7 @@ def y_of(ler: float) -> float: # X-axis tick labels (log-spaced) # Show ticks at 1, 2, 5 * 10^n (standard log-scale subdivisions) x_ticks = set() - for exp in range(int(math.floor(log_p_min)) - 1, int(math.ceil(log_p_max)) + 1): + for exp in range(math.floor(log_p_min) - 1, math.ceil(log_p_max) + 1): for mult in [1.0, 2.0, 5.0]: x_ticks.add(mult * 10.0**exp) # Filter to visible range and limit density @@ -834,10 +834,7 @@ def _threshold_table(estimates: dict) -> list[str]: for est in sorted(estimates.values(), key=lambda e: e.get("estimated_p_th", 0), reverse=True): p_th = est["estimated_p_th"] se = est.get("std_error") - if se: - th_str = f"{_sci(p_th)} +/- {_sci(se)}" - else: - th_str = f"{_sci(p_th)}" + th_str = f"{_sci(p_th)} +/- {_sci(se)}" if se else f"{_sci(p_th)}" lines.append( f" " f"" diff --git a/examples/surface/coherent_noise_sweep.py b/examples/surface/coherent_noise_sweep.py index 06d15cec0..1995878c6 100644 --- a/examples/surface/coherent_noise_sweep.py +++ b/examples/surface/coherent_noise_sweep.py @@ -69,7 +69,7 @@ def run_sweep( """Run a coherent noise sweep using sim_neo.""" from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch from pecos_rslib.qec import ObservableSubgraphDecoder - from pecos_rslib_exp import sim_neo, stab_mps, statevec, depolarizing + from pecos_rslib_exp import depolarizing, sim_neo, stab_mps, statevec patch = SurfacePatch.create(distance=distance) b = LogicalCircuitBuilder() @@ -96,14 +96,8 @@ def run_sweep( for p_idle in p_idle_values: # Simulate t0 = time.perf_counter() - noise = (depolarizing() - .p1(p_depol).p2(p_depol) - .p_meas(p_depol).p_prep(p_depol) - .idle_rz(p_idle)) - builder = (sim_neo(tc) - .noise(noise) - .shots(shots) - .seed(seed)) + noise = depolarizing().p1(p_depol).p2(p_depol).p_meas(p_depol).p_prep(p_depol).idle_rz(p_idle) + builder = sim_neo(tc).noise(noise).shots(shots).seed(seed) if backend == "stabmps": builder = builder.quantum( ( @@ -187,7 +181,7 @@ def write_html_report(sweep: CoherentNoiseSweep, path: Path) -> None: "details .content { padding: 0.5em 0; line-height: 1.6; }", "", f"

    Coherent Idle Noise: {sweep.basis}-basis Memory d={sweep.distance}

    ", - f"

    Depolarizing: p={sweep.p_depol}, rounds={sweep.rounds}, " f"backend={sweep.backend}

    ", + f"

    Depolarizing: p={sweep.p_depol}, rounds={sweep.rounds}, backend={sweep.backend}

    ", f"

    Total time: {sweep.total_seconds:.1f}s

    ", "", "
    About Coherent Idle Noise", @@ -230,12 +224,12 @@ def write_html_report(sweep: CoherentNoiseSweep, path: Path) -> None: if len(sweep.points) >= 2 and sweep.points[0].ler > 0: baseline = sweep.points[0].ler html_parts.append("

    Coherent Amplification

    ") - html_parts.append("
    Circuit{dec}{dec}
    {r.logical_error_rate:.5f} ' f"({r.decode_seconds:.2f}s){r.logical_error_rate:.5f} ({r.decode_seconds:.2f}s)-± SEErrorsvs baseline
    {html_mod.escape(est['decoder'])}{th_str}
    " "") + html_parts.append("
    θLER / baselineLER / twirled
    ") for pt in sweep.points[1:]: ratio = pt.ler / baseline twirl_ratio = pt.ler / pt.p_twirled if pt.p_twirled > 0 else 0 html_parts.append( - f"" f"" f"", + f"", ) html_parts.append("
    θLER / baselineLER / twirled
    {pt.p_idle:.3f}{ratio:.1f}x{twirl_ratio:.0f}x
    {pt.p_idle:.3f}{ratio:.1f}x{twirl_ratio:.0f}x
    ") @@ -252,7 +246,10 @@ def main(): parser.add_argument("--distance", "-d", type=int, default=3) parser.add_argument("--rounds", type=int, default=None, help="Syndrome rounds (default: distance)") parser.add_argument( - "--basis", choices=["X", "Z"], default="X", help="Memory basis (default: X, where RZ noise is visible)" + "--basis", + choices=["X", "Z"], + default="X", + help="Memory basis (default: X, where RZ noise is visible)", ) parser.add_argument("--p-depol", type=float, default=0.003) parser.add_argument("--p-idle", type=float, nargs="+", default=[0.0, 0.01, 0.02, 0.03, 0.05, 0.07, 0.1]) diff --git a/examples/surface/d3_fault_catalog_lookup.rs b/examples/surface/d3_fault_catalog_lookup.rs index 2e6422d87..82b01fe45 100644 --- a/examples/surface/d3_fault_catalog_lookup.rs +++ b/examples/surface/d3_fault_catalog_lookup.rs @@ -5,7 +5,7 @@ //! //! This example keeps the expensive loop in Rust: //! - build a d=3 rotated surface-code Z-memory experiment, -//! - enumerate all k-fault configurations for k <= max_faults, +//! - enumerate all k-fault configurations for k <= `max_faults`, //! - XOR detector / observable effects via `fault_configurations(k)`, //! - aggregate `configuration_probability` into a lookup table. //! @@ -234,33 +234,29 @@ fn build_d3_z_memory_circuit(rounds: usize) -> Result { // Z-check round is deterministic. Without these, an initial data X fault can // flip every repeated Z-check round and the final data parity, cancelling all // later detectors. - for stab_idx in 0..code.num_z_stabilizers() { - detectors.push(relative_records( - num_measurements, - &[z_round_measurements[0][stab_idx]], - )); + for &meas_ref in z_round_measurements[0] + .iter() + .take(code.num_z_stabilizers()) + { + detectors.push(relative_records(num_measurements, &[meas_ref])); } // Repeated syndrome detectors: current stabilizer measurement XOR previous // stabilizer measurement. These are deterministic after the first round. for round in 1..rounds { - for stab_idx in 0..code.num_x_stabilizers() { - detectors.push(relative_records( - num_measurements, - &[ - x_round_measurements[round][stab_idx], - x_round_measurements[round - 1][stab_idx], - ], - )); + for (¤t, &previous) in x_round_measurements[round] + .iter() + .zip(x_round_measurements[round - 1].iter()) + .take(code.num_x_stabilizers()) + { + detectors.push(relative_records(num_measurements, &[current, previous])); } - for stab_idx in 0..code.num_z_stabilizers() { - detectors.push(relative_records( - num_measurements, - &[ - z_round_measurements[round][stab_idx], - z_round_measurements[round - 1][stab_idx], - ], - )); + for (¤t, &previous) in z_round_measurements[round] + .iter() + .zip(z_round_measurements[round - 1].iter()) + .take(code.num_z_stabilizers()) + { + detectors.push(relative_records(num_measurements, &[current, previous])); } } @@ -301,8 +297,12 @@ fn build_d3_z_memory_circuit(rounds: usize) -> Result { } fn relative_records(num_measurements: usize, refs: &[TickMeasRef]) -> Vec { + let num_measurements = i32::try_from(num_measurements).expect("measurement count fits in i32"); refs.iter() - .map(|m| m.record_idx as i32 - num_measurements as i32) + .map(|m| { + i32::try_from(m.record_idx).expect("measurement record index fits in i32") + - num_measurements + }) .collect() } diff --git a/examples/surface/dem_comparison.py b/examples/surface/dem_comparison.py index 9ec8838d9..d9b178981 100644 --- a/examples/surface/dem_comparison.py +++ b/examples/surface/dem_comparison.py @@ -27,13 +27,13 @@ def run(*, distance, rounds, basis, p, shots, seed, run_statevec): from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch - from pecos_rslib.qec import DemBuilder, DagFaultAnalyzer, DemSampler + from pecos_rslib.qec import DagFaultAnalyzer, DemBuilder, DemSampler from pecos_rslib_exp import ( + depolarizing, exact_detection_rates, sim_neo, stabilizer, statevec, - depolarizing, ) patch = SurfacePatch.create(distance=distance) @@ -130,7 +130,7 @@ def extract_det_rates(results): print( f" DemBuilder: {dem_build_time*1000:.0f}ms, FromCircuit: {fc_time:.2f}s," f" Heisenberg: {heis_time*1000:.0f}ms, Stabilizer: {stab_time:.2f}s" - + (f", StateVec: {sv_time:.1f}s" if sv else "") + + (f", StateVec: {sv_time:.1f}s" if sv else ""), ) # Header @@ -148,7 +148,7 @@ def extract_det_rates(results): if s < 0.001: continue - se = math.sqrt(s * (1 - s) / shots) + math.sqrt(s * (1 - s) / shots) r_db = dem_analytical[dd] / s r_fc = dem_fc[dd] / s r_h = heis[dd] / s diff --git a/examples/surface/dem_method_ler_comparison.py b/examples/surface/dem_method_ler_comparison.py index 14f1fc352..84dd7ef28 100644 --- a/examples/surface/dem_method_ler_comparison.py +++ b/examples/surface/dem_method_ler_comparison.py @@ -37,7 +37,8 @@ def _decoder_requires_graphlike(decoder: str) -> bool: """Check if a decoder requires graphlike (decomposed) DEMs.""" from pecos_rslib.qec import decoder_dem_requirement - base = decoder.split(":")[0] + + base = decoder.split(":", maxsplit=1)[0] return decoder_dem_requirement(base) == "graphlike" @@ -48,12 +49,13 @@ def sim_results_to_sample_batch(results, det_json, obs_json, num_meas): and observable flips from observable record XOR definitions. """ import json + from pecos_rslib.qec import SampleBatch dets = det_json if isinstance(det_json, list) else json.loads(det_json) obs = obs_json if isinstance(obs_json, list) else json.loads(obs_json) num_dets = len(dets) - num_obs = len(obs) + len(obs) detection_events = [] observable_masks = [] @@ -99,16 +101,27 @@ def build_tick_circuits(distance: int, num_rounds: int, basis: str): patch = SurfacePatch.create(distance=distance) abstract_tc = _build_surface_tick_circuit_for_native_model( - patch, num_rounds, basis, circuit_source="abstract", + patch, + num_rounds, + basis, + circuit_source="abstract", ) traced_tc = _build_surface_tick_circuit_for_native_model( - patch, num_rounds, basis, circuit_source="traced_qis", + patch, + num_rounds, + basis, + circuit_source="traced_qis", ) return patch, abstract_tc, traced_tc def generate_dems( - abstract_tc, traced_tc, patch, num_rounds, noise_params: dict, basis: str, + abstract_tc, + _traced_tc, + patch, + num_rounds, + noise_params: dict, + basis: str, ) -> list[tuple[str, str, str | None]]: """Generate DEM strings from all methods. @@ -133,12 +146,20 @@ def generate_dems( # 1. from_circuit on traced (non-EEG, stochastic, physical gates) try: raw = generate_circuit_level_dem_from_builder( - patch, num_rounds, noise, basis=basis, - decompose_errors=False, circuit_source="traced_qis", + patch, + num_rounds, + noise, + basis=basis, + decompose_errors=False, + circuit_source="traced_qis", ) decomp = generate_circuit_level_dem_from_builder( - patch, num_rounds, noise, basis=basis, - decompose_errors=True, circuit_source="traced_qis", + patch, + num_rounds, + noise, + basis=basis, + decompose_errors=True, + circuit_source="traced_qis", ) results.append(("from_circuit_traced", raw, decomp)) except Exception as e: @@ -147,12 +168,20 @@ def generate_dems( # 1b. from_circuit on abstract (non-EEG, stochastic, logical gates) try: raw = generate_circuit_level_dem_from_builder( - patch, num_rounds, noise, basis=basis, - decompose_errors=False, circuit_source="abstract", + patch, + num_rounds, + noise, + basis=basis, + decompose_errors=False, + circuit_source="abstract", ) decomp = generate_circuit_level_dem_from_builder( - patch, num_rounds, noise, basis=basis, - decompose_errors=True, circuit_source="abstract", + patch, + num_rounds, + noise, + basis=basis, + decompose_errors=True, + circuit_source="abstract", ) results.append(("from_circuit_abstract", raw, decomp)) except Exception as e: @@ -200,7 +229,8 @@ def _sample_from_sim(tc, noise_params, shots, seed, backend="statevec"): "stab_mps" (handles coherent noise, any distance, approximate). """ import json - from pecos_rslib_exp import depolarizing, sim_neo, stabilizer, statevec, stab_mps + + from pecos_rslib_exp import depolarizing, sim_neo, stab_mps, stabilizer, statevec p1 = noise_params.get("p1", 0.0) p2 = noise_params.get("p2", 0.0) @@ -230,9 +260,7 @@ def _sample_from_sim(tc, noise_params, shots, seed, backend="statevec"): def strip_logical_observable_lines(dem_str: str) -> str: """Remove logical_observable lines that some decoders choke on.""" - return "\n".join( - line for line in dem_str.split("\n") if not line.startswith("logical_observable") - ) + return "\n".join(line for line in dem_str.split("\n") if not line.startswith("logical_observable")) def run_comparison( @@ -262,9 +290,7 @@ def run_comparison( t_circuit = time.perf_counter() - t0 print(f" Circuits built in {t_circuit:.2f}s") - sampler_params = { - k: v for k, v in noise_params.items() if k in ("p1", "p2", "p_meas", "p_prep") - } + sampler_params = {k: v for k, v in noise_params.items() if k in ("p1", "p2", "p_meas", "p_prep")} idle_rz = noise_params.get("idle_rz", 0.0) # Generate samples @@ -272,14 +298,20 @@ def run_comparison( if sample_backend in ("statevec", "stabilizer", "stab_mps"): # Simulator-based sampling batch = _sample_from_sim( - abstract_tc, noise_params, shots, seed, + abstract_tc, + noise_params, + shots, + seed, backend=sample_backend, ) else: # DemSampler: fast, stochastic-only sampling from pecos_rslib.qec import DemSampler + sampler = DemSampler.from_circuit( - traced_tc, **sampler_params, idle_rz=idle_rz if idle_rz > 0 else None, + traced_tc, + **sampler_params, + idle_rz=idle_rz if idle_rz > 0 else None, ) batch = sampler.generate_samples(shots, seed=seed) t_sample = time.perf_counter() - t0 @@ -291,7 +323,7 @@ def run_comparison( t_dems = time.perf_counter() - t0 print(f" Generated {len(dems)} DEMs in {t_dems:.2f}s") for name, dem_str, _decomp in dems: - n_lines = len([l for l in dem_str.strip().split("\n") if l.strip()]) + n_lines = len([line for line in dem_str.strip().split("\n") if line.strip()]) print(f" {name}: {n_lines} lines") # Build column headers: for raw-capable decoders, show both raw and decomposed @@ -316,9 +348,7 @@ def run_comparison( for dem_name, dem_raw, dem_decomp in dems: dem_raw_clean = strip_logical_observable_lines(dem_raw) - dem_decomp_clean = ( - strip_logical_observable_lines(dem_decomp) if dem_decomp else None - ) + dem_decomp_clean = strip_logical_observable_lines(dem_decomp) if dem_decomp else None print(f" {dem_name:<22s}", end="", flush=True) for decoder, dem_type in columns: @@ -338,17 +368,19 @@ def run_comparison( stats = batch.decode_stats(dem, decoder) ler = stats.logical_error_rate print(f" | {ler:>16.4f}", end="") - all_results.append({ - "distance": distance, - "noise": noise_label, - "dem_method": dem_name, - "decoder": decoder, - "dem_type": dem_type, - "num_shots": shots, - "num_errors": stats.num_errors, - "ler": ler, - "decode_s": stats.total_seconds, - }) + all_results.append( + { + "distance": distance, + "noise": noise_label, + "dem_method": dem_name, + "decoder": decoder, + "dem_type": dem_type, + "num_shots": shots, + "num_errors": stats.num_errors, + "ler": ler, + "decode_s": stats.total_seconds, + }, + ) except Exception: # Decoder can't handle this DEM (e.g., hyperedges in graphlike DEM) print(f" | {'N/A':>16s}", end="") @@ -384,24 +416,28 @@ def main(): default="native", choices=["native", "statevec", "stabilizer", "stab_mps"], help="'native' uses DemSampler (fast, stochastic). " - "'statevec' uses exact state vector sim (slow, captures coherent). " - "'stabilizer' uses stabilizer sim (fast, exact for depolarizing). " - "'stab_mps' uses tensor network sim (handles coherent, any distance).", + "'statevec' uses exact state vector sim (slow, captures coherent). " + "'stabilizer' uses stabilizer sim (fast, exact for depolarizing). " + "'stab_mps' uses tensor network sim (handles coherent, any distance).", ) args = parser.parse_args() p2 = args.p2 noise_configs = [] if "depol" in args.noise: - noise_configs.append(( - f"depol(p2={p2})", - {"p1": p2 / 10, "p2": p2, "p_meas": p2, "p_prep": p2, "idle_rz": 0.0}, - )) + noise_configs.append( + ( + f"depol(p2={p2})", + {"p1": p2 / 10, "p2": p2, "p_meas": p2, "p_prep": p2, "idle_rz": 0.0}, + ), + ) if "depol+irz" in args.noise: - noise_configs.append(( - f"depol+irz(p2={p2},irz={args.idle_rz})", - {"p1": p2 / 10, "p2": p2, "p_meas": p2, "p_prep": p2, "idle_rz": args.idle_rz}, - )) + noise_configs.append( + ( + f"depol+irz(p2={p2},irz={args.idle_rz})", + {"p1": p2 / 10, "p2": p2, "p_meas": p2, "p_prep": p2, "idle_rz": args.idle_rz}, + ), + ) results = run_comparison( distances=args.distances, diff --git a/examples/surface/dem_tutorial.py b/examples/surface/dem_tutorial.py index 1ea342cdf..545d66f18 100644 --- a/examples/surface/dem_tutorial.py +++ b/examples/surface/dem_tutorial.py @@ -15,8 +15,8 @@ sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "python" / "quantum-pecos" / "src")) from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch -from pecos_rslib.qec import DemSampler, DetectorErrorModel, DemBuilder, DagFaultAnalyzer -from pecos_rslib_exp import sim_neo, stabilizer, depolarizing +from pecos_rslib.qec import DemSampler, DetectorErrorModel +from pecos_rslib_exp import depolarizing, sim_neo, stabilizer def main(): @@ -31,8 +31,10 @@ def main(): tc = b.to_tick_circuit() print(f"Surface code d={distance}, {tc.num_ticks()} ticks") - print(f" {int(tc.get_meta('num_measurements'))} measurements, " - f"{len(json.loads(tc.get_meta('detectors')))} detectors") + print( + f" {int(tc.get_meta('num_measurements'))} measurements, " + f"{len(json.loads(tc.get_meta('detectors')))} detectors", + ) # ================================================================ # 2. Inspect measurement IDs on gates @@ -65,11 +67,10 @@ def main(): # ================================================================ p = 0.005 dem = DetectorErrorModel.from_circuit(tc, p1=p, p2=p, p_meas=p, p_prep=p) - print(f"\nDetectorErrorModel: {dem.num_detectors} detectors, " - f"{dem.num_observables} observables") + print(f"\nDetectorErrorModel: {dem.num_detectors} detectors, {dem.num_observables} observables") dem_str = dem.to_string() - error_lines = [l for l in dem_str.split("\n") if l.startswith("error(")] + error_lines = [line for line in dem_str.split("\n") if line.startswith("error(")] print(f" {len(error_lines)} DEM events") print(" First 3 events:") for line in error_lines[:3]: diff --git a/examples/surface/dem_vs_stabilizer.py b/examples/surface/dem_vs_stabilizer.py index b34f3911d..5a48f938a 100644 --- a/examples/surface/dem_vs_stabilizer.py +++ b/examples/surface/dem_vs_stabilizer.py @@ -26,8 +26,8 @@ def run_comparison(*, distance, rounds, basis, p, shots, seed): from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch - from pecos_rslib.qec import DemBuilder, DagFaultAnalyzer, DemSampler - from pecos_rslib_exp import sim_neo, stabilizer, depolarizing + from pecos_rslib.qec import DagFaultAnalyzer, DemBuilder, DemSampler + from pecos_rslib_exp import depolarizing, sim_neo, stabilizer patch = SurfacePatch.create(distance=distance) b = LogicalCircuitBuilder() @@ -98,7 +98,7 @@ def run_comparison(*, distance, rounds, basis, p, shots, seed): print(f" DEM sample: {fc_time:.2f}s, Stabilizer: {sim_time:.2f}s ({shots} shots)") print( f" {'Det':>4} {'Analytical':>11} {'FromCirc':>10} {'Stabiliz':>10}" - f" {'SV_se':>8} {'A/Sim':>7} {'FC/Sim':>7}" + f" {'SV_se':>8} {'A/Sim':>7} {'FC/Sim':>7}", ) max_a_err = 0.0 @@ -124,12 +124,11 @@ def run_comparison(*, distance, rounds, basis, p, shots, seed): print( f" D{dd:>2} {analytical[dd]:>11.6f} {dem_fc[dd]:>10.6f} {sv_r:>10.6f}" - f" {se:>8.5f} {ra:>7.3f} {rf:>7.3f}{flag}" + f" {se:>8.5f} {ra:>7.3f} {rf:>7.3f}{flag}", ) print( - f" Max deviation: Analytical={max_a_err*100:.1f}%," - f" FromCircuit={max_fc_err*100:.1f}%, flagged={flagged}" + f" Max deviation: Analytical={max_a_err*100:.1f}%, FromCircuit={max_fc_err*100:.1f}%, flagged={flagged}", ) diff --git a/examples/surface/eeg_formula_comparison.py b/examples/surface/eeg_formula_comparison.py index 9dfdcd754..6b32a607b 100644 --- a/examples/surface/eeg_formula_comparison.py +++ b/examples/surface/eeg_formula_comparison.py @@ -22,7 +22,6 @@ import argparse import json -import math import sys import time from pathlib import Path @@ -48,7 +47,7 @@ def marginals_from_events(events, num_dets): def run(*, distance, rounds, basis, theta_values, shots, seed, run_statevec): from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch - from pecos_rslib_exp import perturbative_dem_events, exact_detection_rates, eeg_per_detector + from pecos_rslib_exp import eeg_per_detector, exact_detection_rates, perturbative_dem_events patch = SurfacePatch.create(distance=distance) b = LogicalCircuitBuilder() @@ -77,7 +76,11 @@ def run(*, distance, rounds, basis, theta_values, shots, seed, run_statevec): # Per-detector computation (cross-event beta) per_det_marginals = {} - for name, h_formula, _ in [("PD-Taylor", "taylor", 0), ("PD-SinSq", "sin_squared", 0), ("PD-ExCom", "exact_commuting", 0)]: + for name, h_formula, _ in [ + ("PD-Taylor", "taylor", 0), + ("PD-SinSq", "sin_squared", 0), + ("PD-ExCom", "exact_commuting", 0), + ]: t0 = time.perf_counter() pd_results = eeg_per_detector(tc, idle_rz=theta, h_formula=h_formula) dt = time.perf_counter() - t0 @@ -99,7 +102,8 @@ def run(*, distance, rounds, basis, theta_values, shots, seed, run_statevec): # StateVec (optional ground truth) sv_rate = None if run_statevec: - from pecos_rslib_exp import sim_neo, statevec, depolarizing + from pecos_rslib_exp import depolarizing, sim_neo, statevec + t0 = time.perf_counter() noise = depolarizing().idle_rz(theta) results = sim_neo(tc).quantum(statevec()).noise(noise).shots(shots).seed(seed).run() @@ -154,9 +158,9 @@ def run(*, distance, rounds, basis, theta_values, shots, seed, run_statevec): if num_dets <= 40: # Show: Heisenberg, Taylor (DEM), PD-Taylor, PD-ExCom, SV show_configs = [ - ("Taylor", lambda: fwd_marginals["Taylor"]), - ("ExSubset", lambda: fwd_marginals["ExSubset"]), - ("PD-Tayl", lambda: per_det_marginals["PD-Taylor"]), + ("Taylor", lambda fwd_marginals=fwd_marginals: fwd_marginals["Taylor"]), + ("ExSubset", lambda fwd_marginals=fwd_marginals: fwd_marginals["ExSubset"]), + ("PD-Tayl", lambda per_det_marginals=per_det_marginals: per_det_marginals["PD-Taylor"]), ] cols = ["Det", "Heisen"] + [n for n, _ in show_configs] if sv_rate is not None: diff --git a/examples/surface/eeg_vs_statevec.py b/examples/surface/eeg_vs_statevec.py index 340eceae0..82fd38915 100644 --- a/examples/surface/eeg_vs_statevec.py +++ b/examples/surface/eeg_vs_statevec.py @@ -38,7 +38,15 @@ def run_comparison( dem_sample: bool, ): from pecos.qec.surface import LogicalCircuitBuilder, SurfacePatch - from pecos_rslib_exp import perturbative_dem, perturbative_dem_events, exact_detection_rates, sim_neo, statevec, depolarizing + from pecos_rslib_exp import ( + coherent_dem_exact, + depolarizing, + exact_detection_rates, + perturbative_dem, + perturbative_dem_events, + sim_neo, + statevec, + ) patch = SurfacePatch.create(distance=distance) b = LogicalCircuitBuilder() @@ -90,7 +98,7 @@ def run_comparison( # Heisenberg DEM → sampler t0 = time.perf_counter() - dem_heis_str = coherent_dem(tc, idle_rz=theta) + dem_heis_str = coherent_dem_exact(tc, idle_rz=theta) sampler_heis = DemSampler.from_dem_string(dem_heis_str) batch_heis = sampler_heis.generate_samples(num_shots=shots, seed=seed) heis_sample_time = time.perf_counter() - t0 @@ -133,12 +141,16 @@ def run_comparison( sv_det_rate = [c / shots for c in sv_det_count] # --- Compare --- - print(f" EEG: {eeg_time*1000:.1f}ms, Heisenberg: {heis_time*1000:.1f}ms, StateVec: {sv_time:.1f}s ({shots} shots)") + print(f" EEG: {eeg_time*1000:.1f}ms, Heisenberg: {heis_time*1000:.1f}ms") + print(f" StateVec: {sv_time:.1f}s ({shots} shots)") if dem_sample: print(f" DEM sample: Taylor {taylor_sample_time:.2f}s, Heisenberg {heis_sample_time:.2f}s ({shots} shots)") if dem_sample: - print(f" {'Det':>4} {'Taylor':>10} {'Heisen':>10} {'T(DEM)':>10} {'H(DEM)':>10} {'StateVec':>10} {'SV_se':>8} {'T/SV':>7} {'H/SV':>7}") + print( + f" {'Det':>4} {'Taylor':>10} {'Heisen':>10} {'T(DEM)':>10} " + f"{'H(DEM)':>10} {'StateVec':>10} {'SV_se':>8} {'T/SV':>7} {'H/SV':>7}", + ) else: print(f" {'Det':>4} {'Taylor':>10} {'Heisen':>10} {'StateVec':>10} {'SV_se':>8} {'T/SV':>7} {'H/SV':>7}") @@ -162,9 +174,15 @@ def run_comparison( if dem_sample: td = taylor_dem_rates[d] if taylor_dem_rates else 0 hd = heis_dem_rates[d] if heis_dem_rates else 0 - print(f" D{d:>3} {tp:>10.6f} {hp:>10.6f} {td:>10.6f} {hd:>10.6f} {sv_r:>10.6f} {sv_se:>8.6f} {t_ratio:>7.3f} {h_ratio:>7.3f}") + print( + f" D{d:>3} {tp:>10.6f} {hp:>10.6f} {td:>10.6f} {hd:>10.6f} " + f"{sv_r:>10.6f} {sv_se:>8.6f} {t_ratio:>7.3f} {h_ratio:>7.3f}", + ) else: - print(f" D{d:>3} {tp:>10.6f} {hp:>10.6f} {sv_r:>10.6f} {sv_se:>8.6f} {t_ratio:>7.3f} {h_ratio:>7.3f}") + print( + f" D{d:>3} {tp:>10.6f} {hp:>10.6f} {sv_r:>10.6f} " + f"{sv_se:>8.6f} {t_ratio:>7.3f} {h_ratio:>7.3f}", + ) print(f" Max rel err: Taylor={max_rel_taylor*100:.1f}%, Heisenberg={max_rel_heis*100:.1f}%") @@ -180,8 +198,7 @@ def main(): parser.add_argument("--theta", type=float, nargs="+", default=[0.01, 0.03, 0.05, 0.1]) parser.add_argument("--shots", type=int, default=20000) parser.add_argument("--seed", type=int, default=42) - parser.add_argument("--dem-sample", action="store_true", - help="Also sample from both DEMs and compare rates") + parser.add_argument("--dem-sample", action="store_true", help="Also sample from both DEMs and compare rates") args = parser.parse_args() for dist in args.distance: diff --git a/examples/surface/ml_lookup_decoder.py b/examples/surface/ml_lookup_decoder.py index dba9fb64c..6fefa9ca2 100644 --- a/examples/surface/ml_lookup_decoder.py +++ b/examples/surface/ml_lookup_decoder.py @@ -70,27 +70,34 @@ def main(): parser.add_argument("--p2", type=float, default=0.005) parser.add_argument("--idle-rz", type=float, default=0.0) parser.add_argument( - "--sample-backend", default="stabilizer", + "--sample-backend", + default="stabilizer", choices=["stabilizer", "statevec", "native"], ) args = parser.parse_args() import json + from pecos.qec.surface import SurfacePatch from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model patch = SurfacePatch.create(distance=args.distance) num_rounds = 2 * args.distance tc = _build_surface_tick_circuit_for_native_model( - patch, num_rounds, args.basis, circuit_source="abstract", + patch, + num_rounds, + args.basis, + circuit_source="abstract", ) num_dets = len(json.loads(tc.get_meta("detectors"))) print(f"d={args.distance}, {num_rounds} rounds, {num_dets} detectors, {2**num_dets} possible syndromes") noise_params = { - "p1": args.p2 / 10, "p2": args.p2, - "p_meas": args.p2, "p_prep": args.p2, + "p1": args.p2 / 10, + "p2": args.p2, + "p_meas": args.p2, + "p_prep": args.p2, "idle_rz": args.idle_rz, } @@ -99,11 +106,16 @@ def main(): t0 = time.perf_counter() if args.sample_backend in ("stabilizer", "statevec"): - from pecos_rslib_exp import depolarizing, sim_neo, stabilizer, statevec from pecos_rslib.qec import SampleBatch + from pecos_rslib_exp import depolarizing, sim_neo, stabilizer, statevec - noise = depolarizing().p1(noise_params["p1"]).p2(noise_params["p2"]) \ - .p_meas(noise_params["p_meas"]).p_prep(noise_params["p_prep"]) + noise = ( + depolarizing() + .p1(noise_params["p1"]) + .p2(noise_params["p2"]) + .p_meas(noise_params["p_meas"]) + .p_prep(noise_params["p_prep"]) + ) if args.idle_rz > 0: noise = noise.idle_rz(args.idle_rz) @@ -141,6 +153,7 @@ def main(): train_batch = SampleBatch(detection_events, observable_masks) else: from pecos_rslib.qec import DemSampler + sampler_params = {k: v for k, v in noise_params.items() if k in ("p1", "p2", "p_meas", "p_prep")} sampler = DemSampler.from_circuit(tc, **sampler_params) train_batch = sampler.generate_samples(args.shots, seed=args.seed) @@ -192,24 +205,34 @@ def main(): ler_lookup = errors_lookup / n # Compare with pymatching - from pecos.qec.surface.decode import generate_circuit_level_dem_from_builder from pecos.qec.surface import NoiseModel + from pecos.qec.surface.decode import generate_circuit_level_dem_from_builder + noise_obj = NoiseModel( - p1=noise_params["p1"], p2=noise_params["p2"], - p_meas=noise_params["p_meas"], p_prep=noise_params["p_prep"], + p1=noise_params["p1"], + p2=noise_params["p2"], + p_meas=noise_params["p_meas"], + p_prep=noise_params["p_prep"], ) dem_decomp = generate_circuit_level_dem_from_builder( - patch, num_rounds, noise_obj, basis=args.basis, - decompose_errors=True, circuit_source="abstract", + patch, + num_rounds, + noise_obj, + basis=args.basis, + decompose_errors=True, + circuit_source="abstract", ) - dem_clean = "\n".join(l for l in dem_decomp.split("\n") if not l.startswith("logical_observable")) + dem_clean = "\n".join(line for line in dem_decomp.split("\n") if not line.startswith("logical_observable")) stats_pm = test_batch.decode_stats(dem_clean, "pymatching") # Compare with coherent_dem_decomposed if available try: from pecos_rslib_exp import coherent_dem_decomposed + _, coherent_decomp = coherent_dem_decomposed(tc, **noise_params) - coherent_clean = "\n".join(l for l in coherent_decomp.split("\n") if not l.startswith("logical_observable")) + coherent_clean = "\n".join( + line for line in coherent_decomp.split("\n") if not line.startswith("logical_observable") + ) stats_coherent = test_batch.decode_stats(coherent_clean, "pymatching") ler_coherent = stats_coherent.logical_error_rate except Exception: diff --git a/examples/surface/validate_dem_correlations.py b/examples/surface/validate_dem_correlations.py index b3d008ee8..78f84ed9e 100644 --- a/examples/surface/validate_dem_correlations.py +++ b/examples/surface/validate_dem_correlations.py @@ -32,7 +32,10 @@ def build_circuit(distance, rounds, basis, circuit_source): from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model tc = _build_surface_tick_circuit_for_native_model( - patch, rounds, basis, circuit_source="traced_qis", + patch, + rounds, + basis, + circuit_source="traced_qis", ) tc.lower_clifford_rotations() tc.assign_missing_meas_ids() @@ -106,8 +109,19 @@ def format_matrix(matrix, width=8, precision=5): return "\n".join(lines) -def run_validation(*, distances, bases, rounds_per_d, shots, seed, circuit_sources, - noise_configs, threshold, show_matrices, max_order): +def run_validation( + *, + distances, + bases, + rounds_per_d, + shots, + seed, + circuit_sources, + noise_configs, + threshold, + show_matrices, + max_order, +): from pecos.qec.analysis import ( compare_flip_matrices, compare_k_body_rates, @@ -129,8 +143,10 @@ def run_validation(*, distances, bases, rounds_per_d, shots, seed, circuit_sourc src_label = f" [{source}]" if len(circuit_sources) > 1 else "" print(f"\n{'=' * 72}") - print(f"d={distance} {basis}-basis{src_label}, {num_dets} detectors, " - f"{n_ancilla} per round, {rounds} rounds") + print( + f"d={distance} {basis}-basis{src_label}, {num_dets} detectors, " + f"{n_ancilla} per round, {rounds} rounds", + ) print(f"{'=' * 72}") for noise_label, noise_kw in noise_configs: @@ -146,7 +162,7 @@ def run_validation(*, distances, bases, rounds_per_d, shots, seed, circuit_sourc all_pass = True round_results = [] - for r_idx, (sm, dm) in enumerate(zip(sim_mats, dem_mats)): + for r_idx, (sm, dm) in enumerate(zip(sim_mats, dem_mats, strict=False)): max_err, frob_err, worst = compare_flip_matrices(sm, dm) ok = max_err <= threshold if not ok: @@ -155,14 +171,20 @@ def run_validation(*, distances, bases, rounds_per_d, shots, seed, circuit_sourc # --- Higher-order correlations --- sim_kbody = detector_k_body_rates_by_round( - sim_events, nd, n_ancilla, max_order=max_order, + sim_events, + nd, + n_ancilla, + max_order=max_order, ) dem_kbody = detector_k_body_rates_by_round( - dem_events, nd, n_ancilla, max_order=max_order, + dem_events, + nd, + n_ancilla, + max_order=max_order, ) kbody_results = [] # (round, order, max_err, rms_err, worst, ok) - for r_idx, (sr, dr) in enumerate(zip(sim_kbody, dem_kbody)): + for r_idx, (sr, dr) in enumerate(zip(sim_kbody, dem_kbody, strict=False)): order_stats = compare_k_body_rates(sr, dr, max_order=max_order) for order, (me, rms, worst_ev) in order_stats.items(): ok = me <= threshold @@ -177,8 +199,9 @@ def run_validation(*, distances, bases, rounds_per_d, shots, seed, circuit_sourc total_pass += 1 else: total_fail += 1 - failures.append(f"d={distance} {basis} {source} {noise_label}: " - f"{worst_round_err * 100:.0f}%") + failures.append( + f"d={distance} {basis} {source} {noise_label}: {worst_round_err * 100:.0f}%", + ) print(f"\n {noise_label} (sim: {sim_time:.2f}s) {status}") @@ -186,45 +209,46 @@ def run_validation(*, distances, bases, rounds_per_d, shots, seed, circuit_sourc print(" Pairwise (flip matrices):") for r_idx, max_err, frob_err, worst, ok in round_results: flag = "" if ok else " <-- FAIL" - print(f" Round {r_idx}: max_rel={max_err * 100:5.1f}% " - f"frob_rel={frob_err * 100:5.1f}% " - f"worst={worst}{flag}") + print( + f" Round {r_idx}: max_rel={max_err * 100:5.1f}% " + f"frob_rel={frob_err * 100:5.1f}% " + f"worst={worst}{flag}", + ) # Higher-order per-round summary for order in range(1, max_order + 1): - order_entries = [(r, me, rms, w, ok) - for r, o, me, rms, w, ok in kbody_results - if o == order] + order_entries = [(r, me, rms, w, ok) for r, o, me, rms, w, ok in kbody_results if o == order] if not order_entries: continue worst_me = max(e[1] for e in order_entries) avg_rms = sum(e[2] for e in order_entries) / len(order_entries) - label = {1: "1-body (marginals)", 2: "2-body (pairs)", - 3: "3-body (triples)", 4: "4-body (quads)"}.get( - order, f"{order}-body") + label = { + 1: "1-body (marginals)", + 2: "2-body (pairs)", + 3: "3-body (triples)", + 4: "4-body (quads)", + }.get(order, f"{order}-body") any_fail = any(not e[4] for e in order_entries) flag = " <-- FAIL" if any_fail else "" - print(f" {label}: worst_max_rel={worst_me * 100:5.1f}% " - f"avg_rms_rel={avg_rms * 100:5.1f}%{flag}") + print( + f" {label}: worst_max_rel={worst_me * 100:5.1f}% " + f"avg_rms_rel={avg_rms * 100:5.1f}%{flag}", + ) if any_fail: - for r, me, rms, w, ok in order_entries: + for r, me, _rms, w, ok in order_entries: if not ok: - print(f" Round {r}: max_rel={me * 100:.1f}% " - f"worst={w}") + print(f" Round {r}: max_rel={me * 100:.1f}% worst={w}") if show_matrices and not all_pass: - for r_idx, max_err, _, _, ok in round_results: + for r_idx, _max_err, _, _, ok in round_results: if not ok: print(f"\n Round {r_idx} sim:") - print(" " + format_matrix( - sim_mats[r_idx]).replace("\n", "\n ")) + print(" " + format_matrix(sim_mats[r_idx]).replace("\n", "\n ")) print(f" Round {r_idx} dem:") - print(" " + format_matrix( - dem_mats[r_idx]).replace("\n", "\n ")) + print(" " + format_matrix(dem_mats[r_idx]).replace("\n", "\n ")) print(f"\n{'=' * 72}") - print(f"SUMMARY: {total_pass}/{total_pass + total_fail} passed " - f"(threshold: {threshold * 100:.0f}%)") + print(f"SUMMARY: {total_pass}/{total_pass + total_fail} passed (threshold: {threshold * 100:.0f}%)") if failures: print("Failures:") for f in failures: @@ -238,33 +262,29 @@ def main(): parser = argparse.ArgumentParser( description="Validate DEM detector correlations against simulation.", ) - parser.add_argument("--distance", "-d", type=int, nargs="+", default=[2, 3], - help="Code distances (default: 2 3)") - parser.add_argument("--basis", type=str, nargs="+", default=["Z"], - choices=["Z", "X"], help="Bases (default: Z)") - parser.add_argument("--rounds", type=int, default=None, - help="Syndrome rounds (default: same as distance)") - parser.add_argument("--shots", type=int, default=100000, - help="Shots per test (default: 100000)") + parser.add_argument("--distance", "-d", type=int, nargs="+", default=[2, 3], help="Code distances (default: 2 3)") + parser.add_argument("--basis", type=str, nargs="+", default=["Z"], choices=["Z", "X"], help="Bases (default: Z)") + parser.add_argument("--rounds", type=int, default=None, help="Syndrome rounds (default: same as distance)") + parser.add_argument("--shots", type=int, default=100000, help="Shots per test (default: 100000)") parser.add_argument("--seed", type=int, default=42) - parser.add_argument("--circuit-source", choices=["abstract", "traced_qis", "both"], - default="both", help="Circuit pipeline (default: both)") - parser.add_argument("--threshold", type=float, default=0.20, - help="Max relative error threshold (default: 0.20)") - parser.add_argument("--max-order", type=int, default=3, - help="Max correlation order (default: 3)") - parser.add_argument("--show-matrices", action="store_true", - help="Print matrices for failing rounds") + parser.add_argument( + "--circuit-source", + choices=["abstract", "traced_qis", "both"], + default="both", + help="Circuit pipeline (default: both)", + ) + parser.add_argument("--threshold", type=float, default=0.20, help="Max relative error threshold (default: 0.20)") + parser.add_argument("--max-order", type=int, default=3, help="Max correlation order (default: 3)") + parser.add_argument("--show-matrices", action="store_true", help="Print matrices for failing rounds") args = parser.parse_args() - sources = (["abstract", "traced_qis"] if args.circuit_source == "both" - else [args.circuit_source]) + sources = ["abstract", "traced_qis"] if args.circuit_source == "both" else [args.circuit_source] noise_configs = [ - ("p_meas=0.01", {"p1": 0.0, "p2": 0.0, "p_meas": 0.01, "p_prep": 0.0}), - ("p2=0.01", {"p1": 0.0, "p2": 0.01, "p_meas": 0.0, "p_prep": 0.0}), - ("depol", {"p1": 0.001, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01}), + ("p_meas=0.01", {"p1": 0.0, "p2": 0.0, "p_meas": 0.01, "p_prep": 0.0}), + ("p2=0.01", {"p1": 0.0, "p2": 0.01, "p_meas": 0.0, "p_prep": 0.0}), + ("depol", {"p1": 0.001, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01}), ("strong_depol", {"p1": 0.005, "p2": 0.05, "p_meas": 0.05, "p_prep": 0.05}), ] diff --git a/examples/surface/validate_dem_generators.py b/examples/surface/validate_dem_generators.py index d04da8486..66efd020a 100644 --- a/examples/surface/validate_dem_generators.py +++ b/examples/surface/validate_dem_generators.py @@ -20,7 +20,6 @@ import argparse import json -import math import sys import time from pathlib import Path @@ -33,25 +32,25 @@ # "statevec" for coherent noise (exact, limited to small circuits) NOISE_CONFIGS = [ # Depolarizing components (ground truth: stabilizer) - ("p_meas only", dict(p_meas=0.01), "stabilizer"), - ("p_prep only", dict(p_prep=0.01), "stabilizer"), - ("p1 only", dict(p1=0.01), "stabilizer"), - ("p2 only", dict(p2=0.01), "stabilizer"), - ("depol all", dict(p1=0.005, p2=0.005, p_meas=0.005, p_prep=0.005), "stabilizer"), - ("depol strong", dict(p1=0.01, p2=0.01, p_meas=0.01, p_prep=0.01), "stabilizer"), + ("p_meas only", {"p_meas": 0.01}, "stabilizer"), + ("p_prep only", {"p_prep": 0.01}, "stabilizer"), + ("p1 only", {"p1": 0.01}, "stabilizer"), + ("p2 only", {"p2": 0.01}, "stabilizer"), + ("depol all", {"p1": 0.005, "p2": 0.005, "p_meas": 0.005, "p_prep": 0.005}, "stabilizer"), + ("depol strong", {"p1": 0.01, "p2": 0.01, "p_meas": 0.01, "p_prep": 0.01}, "stabilizer"), ] # Coherent noise configs (ground truth: statevec, small circuits only) COHERENT_CONFIGS = [ - ("idle_rz only", dict(idle_rz=0.05), "statevec"), - ("rz+depol", dict(idle_rz=0.05, p1=0.005, p2=0.005, p_meas=0.005, p_prep=0.005), "statevec"), + ("idle_rz only", {"idle_rz": 0.05}, "statevec"), + ("rz+depol", {"idle_rz": 0.05, "p1": 0.005, "p2": 0.005, "p_meas": 0.005, "p_prep": 0.005}, "statevec"), ] # Threshold for pass/fail (relative error vs stabilizer) THRESHOLD = 0.15 # 15% — accounts for statistical noise at moderate shot counts -def build_circuit(distance, rounds, basis, circuit_source="abstract", fill_idle=False): +def build_circuit(distance, rounds, basis, circuit_source="abstract", *, fill_idle=False): """Build surface code TickCircuit. circuit_source: @@ -67,14 +66,19 @@ def build_circuit(distance, rounds, basis, circuit_source="abstract", fill_idle= if circuit_source == "traced_qis": from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model + tc = _build_surface_tick_circuit_for_native_model( - patch, rounds, basis, circuit_source="traced_qis", + patch, + rounds, + basis, + circuit_source="traced_qis", ) # Compilation passes for traced QIS circuits: - tc.lower_clifford_rotations() # RZ(pi/2) -> SZ, etc. - tc.assign_missing_meas_ids() # Stamp MeasId on MZ gates + tc.lower_clifford_rotations() # RZ(pi/2) -> SZ, etc. + tc.assign_missing_meas_ids() # Stamp MeasId on MZ gates else: from pecos.qec.surface import LogicalCircuitBuilder + b = LogicalCircuitBuilder() b.add_patch(patch, "Q0") b.add_memory("Q0", rounds=rounds, basis=basis) @@ -92,7 +96,7 @@ def build_circuit(distance, rounds, basis, circuit_source="abstract", fill_idle= def ground_truth_rates(tc, noise_kw, shots, seed, det_json, num_meas, num_dets, simulator="stabilizer"): """Ground truth: simulation with detector extraction.""" - from pecos_rslib_exp import sim_neo, stabilizer, statevec, depolarizing + from pecos_rslib_exp import depolarizing, sim_neo, stabilizer, statevec noise = depolarizing() for k, v in noise_kw.items(): @@ -144,7 +148,7 @@ def dem_sampler_rates(tc, noise_kw, shots, seed, num_dets): def dem_builder_rates(tc, noise_kw, shots, seed, num_dets): """DemBuilder path (explicit, uses .to_sampler()).""" - from pecos_rslib.qec import DemBuilder, DagFaultAnalyzer + from pecos_rslib.qec import DagFaultAnalyzer, DemBuilder dag = tc.to_dag_circuit() analyzer = DagFaultAnalyzer(dag) @@ -196,7 +200,7 @@ def perturbative_rates(tc, noise_kw, num_dets): def max_rel_error(test_rates, ref_rates, min_rate=0.003): """Max relative error across detectors with rate > min_rate.""" max_err = 0.0 - for t, r in zip(test_rates, ref_rates): + for t, r in zip(test_rates, ref_rates, strict=False): if r > min_rate: max_err = max(max_err, abs(t / r - 1)) return max_err @@ -219,96 +223,102 @@ def run_validation(*, distances, bases, shots, seed, verbose, circuit_sources, f for distance in distances: for basis in bases: - for circuit_source in circuit_sources: - try: - tc = build_circuit(distance, distance, basis, circuit_source, fill_idle) - except Exception as e: - print(f"\n d={distance} {basis} [{circuit_source}]: SKIP ({e})") - continue - - det_json = json.loads(tc.get_meta("detectors")) - num_meas = int(tc.get_meta("num_measurements")) - num_dets = len(det_json) - - src_label = f" [{circuit_source}]" if len(circuit_sources) > 1 else "" - print(f"\n{'='*72}") - print(f"d={distance} {basis}-basis{src_label}, {num_dets} detectors, {num_meas} measurements") - print(f"{'='*72}") - - # Combine depolarizing + coherent configs - all_configs = list(NOISE_CONFIGS) + list(COHERENT_CONFIGS) - - for noise_label, noise_kw, gt_simulator in all_configs: - is_coherent = "idle_rz" in noise_kw - - # Ground truth - t0 = time.perf_counter() + for circuit_source in circuit_sources: try: - ref = ground_truth_rates( - tc, noise_kw, shots, seed, det_json, num_meas, num_dets, - simulator=gt_simulator, - ) - except BaseException as e: - if verbose: - print(f"\n {noise_label}: SKIP ground truth ({type(e).__name__}: {e})") + tc = build_circuit(distance, distance, basis, circuit_source, fill_idle=fill_idle) + except Exception as e: + print(f"\n d={distance} {basis} [{circuit_source}]: SKIP ({e})") continue - ref_time = time.perf_counter() - t0 - if verbose: - print(f"\n {noise_label} ({gt_simulator}: {ref_time:.2f}s)") + det_json = json.loads(tc.get_meta("detectors")) + num_meas = int(tc.get_meta("num_measurements")) + num_dets = len(det_json) - for gen_name, gen_func, supports_coherent in generators: - # Skip non-EEG generators for coherent noise - if is_coherent and not supports_coherent: - if verbose: - print(f" {gen_name:<14} (skipped: no coherent support)") - continue + src_label = f" [{circuit_source}]" if len(circuit_sources) > 1 else "" + print(f"\n{'='*72}") + print(f"d={distance} {basis}-basis{src_label}, {num_dets} detectors, {num_meas} measurements") + print(f"{'='*72}") + + # Combine depolarizing + coherent configs + all_configs = list(NOISE_CONFIGS) + list(COHERENT_CONFIGS) + + for noise_label, noise_kw, gt_simulator in all_configs: + is_coherent = "idle_rz" in noise_kw + + # Ground truth t0 = time.perf_counter() try: - if gen_name == "Heisenberg": - test = heisenberg_rates(tc, noise_kw, num_dets) - elif gen_name == "Perturbative": - test = perturbative_rates(tc, noise_kw, num_dets) - else: - test = gen_func(tc, noise_kw, shots, seed, num_dets) - dt = time.perf_counter() - t0 - - err = max_rel_error(test, ref) - ok = err < THRESHOLD - total_tests += 1 - if ok: - total_pass += 1 - else: + ref = ground_truth_rates( + tc, + noise_kw, + shots, + seed, + det_json, + num_meas, + num_dets, + simulator=gt_simulator, + ) + except BaseException as e: + if verbose: + print(f"\n {noise_label}: SKIP ground truth ({type(e).__name__}: {e})") + continue + ref_time = time.perf_counter() - t0 + + if verbose: + print(f"\n {noise_label} ({gt_simulator}: {ref_time:.2f}s)") + + for gen_name, gen_func, supports_coherent in generators: + # Skip non-EEG generators for coherent noise + if is_coherent and not supports_coherent: + if verbose: + print(f" {gen_name:<14} (skipped: no coherent support)") + continue + t0 = time.perf_counter() + try: + if gen_name == "Heisenberg": + test = heisenberg_rates(tc, noise_kw, num_dets) + elif gen_name == "Perturbative": + test = perturbative_rates(tc, noise_kw, num_dets) + else: + test = gen_func(tc, noise_kw, shots, seed, num_dets) + dt = time.perf_counter() - t0 + + err = max_rel_error(test, ref) + ok = err < THRESHOLD + total_tests += 1 + if ok: + total_pass += 1 + else: + total_fail += 1 + failures.append( + f"d={distance} {basis} {noise_label} {gen_name}: {err*100:.0f}%", + ) + + status = "PASS" if ok else f"FAIL({err*100:.0f}%)" + if verbose: + print(f" {gen_name:<14} {dt*1000:>7.0f}ms {status}") + elif not ok: + print(f" {noise_label:<14} {gen_name:<14} {status}") + + except Exception as e: + total_tests += 1 total_fail += 1 failures.append( - f"d={distance} {basis} {noise_label} {gen_name}: {err*100:.0f}%" + f"d={distance} {basis} {noise_label} {gen_name}: ERROR {e}", ) + if verbose: + print(f" {gen_name:<14} ERROR: {e}") - status = "PASS" if ok else f"FAIL({err*100:.0f}%)" - if verbose: - print(f" {gen_name:<14} {dt*1000:>7.0f}ms {status}") - elif not ok: - print(f" {noise_label:<14} {gen_name:<14} {status}") - - except Exception as e: - total_tests += 1 - total_fail += 1 - failures.append( - f"d={distance} {basis} {noise_label} {gen_name}: ERROR {e}" - ) - if verbose: - print(f" {gen_name:<14} ERROR: {e}") - - if not verbose: - # Print summary for this config - pass + if not verbose: + # Print summary for this config + pass # Final summary print(f"\n{'='*72}") print(f"VALIDATION SUMMARY: {total_pass}/{total_tests} passed, {total_fail} failed") print(f"Threshold: {THRESHOLD*100:.0f}% relative error ({shots} shots)") if failures: - print(f"\nFailures:") + print("\nFailures:") for f in failures: print(f" {f}") else: @@ -324,39 +334,51 @@ def main(): formatter_class=argparse.RawDescriptionHelpFormatter, ) parser.add_argument( - "--distance", "-d", type=int, nargs="+", default=[2, 3], - help="Code distances to test (default: 2 3)" + "--distance", + "-d", + type=int, + nargs="+", + default=[2, 3], + help="Code distances to test (default: 2 3)", ) parser.add_argument( - "--basis", choices=["X", "Z"], nargs="+", default=["Z", "X"], - help="Bases to test (default: Z X)" + "--basis", + choices=["X", "Z"], + nargs="+", + default=["Z", "X"], + help="Bases to test (default: Z X)", ) parser.add_argument( - "--shots", type=int, default=20000, - help="Shots per test (default: 20000)" + "--shots", + type=int, + default=20000, + help="Shots per test (default: 20000)", ) parser.add_argument( - "--seed", type=int, default=42, + "--seed", + type=int, + default=42, ) parser.add_argument( - "--verbose", "-v", action="store_true", - help="Show per-generator timing and results" + "--verbose", + "-v", + action="store_true", + help="Show per-generator timing and results", ) parser.add_argument( - "--circuit-source", choices=["abstract", "traced_qis", "both"], + "--circuit-source", + choices=["abstract", "traced_qis", "both"], default="abstract", - help="Circuit construction pipeline (default: abstract)" + help="Circuit construction pipeline (default: abstract)", ) parser.add_argument( - "--fill-idle", action="store_true", - help="Insert Idle(1) gates on inactive qubits (needed for idle_rz noise)" + "--fill-idle", + action="store_true", + help="Insert Idle(1) gates on inactive qubits (needed for idle_rz noise)", ) args = parser.parse_args() - if args.circuit_source == "both": - sources = ["abstract", "traced_qis"] - else: - sources = [args.circuit_source] + sources = ["abstract", "traced_qis"] if args.circuit_source == "both" else [args.circuit_source] ok = run_validation( distances=args.distance, diff --git a/exp/pecos-eeg/examples/profile_heisenberg.rs b/exp/pecos-eeg/examples/profile_heisenberg.rs index 5a3c4adca..f96ea235f 100644 --- a/exp/pecos-eeg/examples/profile_heisenberg.rs +++ b/exp/pecos-eeg/examples/profile_heisenberg.rs @@ -1,17 +1,17 @@ //! Profile the Heisenberg DEM build. -//! Usage: cargo run -p pecos-eeg --example profile_heisenberg --profile profiling -//! Perf: perf record -g -F 4999 -- target/profiling/examples/profile_heisenberg +//! Usage: cargo run -p pecos-eeg --example `profile_heisenberg` --profile profiling +//! Perf: perf record -g -F 4999 -- `target/profiling/examples/profile_heisenberg` use pecos_core::gate_type::GateType; use pecos_core::pauli::pauli_bitmask::BitmaskStorage; -use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; +use pecos_core::{Gate, GateAngles, GateParams, QubitId}; use pecos_eeg::Bm; use std::time::Instant; fn gate(gt: GateType, qubits: &[usize]) -> Gate { Gate { gate_type: gt, - qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + qubits: qubits.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), @@ -88,7 +88,8 @@ fn main() { } } let total = t.elapsed(); - let per_det = total.as_secs_f64() * 1000.0 / (detectors.len() * iters) as f64; + let calls = u32::try_from(detectors.len() * iters).expect("profile call count fits in u32"); + let per_det = total.as_secs_f64() * 1000.0 / f64::from(calls); eprintln!( "{iters} iterations x {} dets = {} calls in {:.2}s ({:.2}ms/det)", detectors.len(), diff --git a/exp/pecos-eeg/src/circuit.rs b/exp/pecos-eeg/src/circuit.rs index 79d2b3de7..2f397f82a 100644 --- a/exp/pecos-eeg/src/circuit.rs +++ b/exp/pecos-eeg/src/circuit.rs @@ -368,12 +368,12 @@ fn conjugate_by_gate(label: &Bm, gate: &Gate) -> Option Gate { Gate { gate_type: gt, - qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + qubits: qubits.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), diff --git a/exp/pecos-eeg/src/dem_mapping.rs b/exp/pecos-eeg/src/dem_mapping.rs index 3eb475278..725e2857f 100644 --- a/exp/pecos-eeg/src/dem_mapping.rs +++ b/exp/pecos-eeg/src/dem_mapping.rs @@ -1456,12 +1456,12 @@ mod tests { // Constructive: p = (h1+h2)^2 use crate::stabilizer::StabilizerGroup; use pecos_core::gate_type::GateType; - use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; + use pecos_core::{Gate, GateAngles, GateParams, QubitId}; fn g(gt: GateType, qs: &[usize]) -> Gate { Gate { gate_type: gt, - qubits: GateQubits::from_iter(qs.iter().map(|&q| QubitId(q))), + qubits: qs.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), @@ -1511,12 +1511,12 @@ mod tests { // Destructive: p = (h1-h2)^2 use crate::stabilizer::StabilizerGroup; use pecos_core::gate_type::GateType; - use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; + use pecos_core::{Gate, GateAngles, GateParams, QubitId}; fn g(gt: GateType, qs: &[usize]) -> Gate { Gate { gate_type: gt, - qubits: GateQubits::from_iter(qs.iter().map(|&q| QubitId(q))), + qubits: qs.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), @@ -1570,12 +1570,12 @@ mod tests { // h1 = h2 = 0.1, -1 stabilizer product → p = (h1-h2)^2 = 0 use crate::stabilizer::StabilizerGroup; use pecos_core::gate_type::GateType; - use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; + use pecos_core::{Gate, GateAngles, GateParams, QubitId}; fn g(gt: GateType, qs: &[usize]) -> Gate { Gate { gate_type: gt, - qubits: GateQubits::from_iter(qs.iter().map(|&q| QubitId(q))), + qubits: qs.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), diff --git a/exp/pecos-eeg/src/heisenberg.rs b/exp/pecos-eeg/src/heisenberg.rs index 671897ad2..88a0cafcf 100644 --- a/exp/pecos-eeg/src/heisenberg.rs +++ b/exp/pecos-eeg/src/heisenberg.rs @@ -1879,12 +1879,16 @@ pub fn heisenberg_exact_from_circuit( // --- Matrix helpers for exact Heisenberg --- +fn bit_to_f64(value: usize) -> f64 { + f64::from(u8::try_from(value).expect("bit value fits in u8")) +} + fn matrix_rz_adjoint(re: &mut [f64], im: &mut [f64], q: usize, theta: f64, n: usize) { let dim = 1usize << n; for i in 0..dim { - let bi = ((i >> q) & 1) as f64; + let bi = bit_to_f64((i >> q) & 1); for j in 0..dim { - let bj = ((j >> q) & 1) as f64; + let bj = bit_to_f64((j >> q) & 1); let phase = (bi - bj) * theta; if phase.abs() < 1e-20 { continue; @@ -2022,12 +2026,12 @@ mod tests { use super::*; use crate::expand; use crate::noise::UniformNoise; - use pecos_core::{GateAngles, GateParams, GateQubits, QubitId}; + use pecos_core::{GateAngles, GateParams, QubitId}; fn gate(gt: GateType, qubits: &[usize]) -> Gate { Gate { gate_type: gt, - qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + qubits: qubits.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), @@ -2479,7 +2483,7 @@ mod tests { /// Builds larger circuits and measures per-detector walk time with both /// implementations. Verifies results match exactly. #[test] - #[ignore] // run with: cargo test -p pecos-eeg -- bench_sparse_scaling --ignored --nocapture + #[ignore = "benchmark; run manually with --ignored --nocapture"] fn bench_sparse_scaling() { use std::time::Instant; diff --git a/exp/pecos-eeg/src/stabilizer.rs b/exp/pecos-eeg/src/stabilizer.rs index 867d6c53b..400b435ac 100644 --- a/exp/pecos-eeg/src/stabilizer.rs +++ b/exp/pecos-eeg/src/stabilizer.rs @@ -139,12 +139,12 @@ impl StabilizerGroup { #[cfg(test)] mod tests { use super::*; - use pecos_core::{GateAngles, GateParams, GateQubits}; + use pecos_core::{GateAngles, GateParams}; fn gate(gt: GateType, qubits: &[usize]) -> Gate { Gate { gate_type: gt, - qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + qubits: qubits.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), diff --git a/exp/pecos-eeg/src/strong_sim.rs b/exp/pecos-eeg/src/strong_sim.rs index d1242004a..13795e3d0 100644 --- a/exp/pecos-eeg/src/strong_sim.rs +++ b/exp/pecos-eeg/src/strong_sim.rs @@ -578,8 +578,7 @@ mod tests { let phi = compute_phi(&Bm::x(0), &Bm::x(0), &[true], &stabs, &phases); assert!( (phi.0 - 1.0).abs() < 1e-10, - "Phi(X,X) at |1> for |0> state: got {:?}", - phi + "Phi(X,X) at |1> for |0> state: got {phi:?}" ); // Φ(Z,I) for outcome 0: ⟨0|Z|0⟩·⟨0|0⟩ = 1·1 = 1 @@ -601,7 +600,7 @@ mod tests { &stabs, &phases, ); - assert!((phi.0 - 1.0).abs() < 1e-10, "Phi(I,I) at 00: {:?}", phi); + assert!((phi.0 - 1.0).abs() < 1e-10, "Phi(I,I) at 00: {phi:?}"); // Φ(I,I) for outcome 01 (not in support): 0 let phi = compute_phi( @@ -615,11 +614,11 @@ mod tests { // Φ(Z0,I) for outcome 00 let phi = compute_phi(&Bm::z(0), &Bm::default(), &[false, false], &stabs, &phases); - assert!((phi.0 - 1.0).abs() < 1e-10, "Phi(Z0,I) at 00: {:?}", phi); + assert!((phi.0 - 1.0).abs() < 1e-10, "Phi(Z0,I) at 00: {phi:?}"); // Φ(Z0,I) for outcome 11 let phi = compute_phi(&Bm::z(0), &Bm::default(), &[true, true], &stabs, &phases); - assert!((phi.0 + 1.0).abs() < 1e-10, "Phi(Z0,I) at 11: {:?}", phi); + assert!((phi.0 + 1.0).abs() < 1e-10, "Phi(Z0,I) at 11: {phi:?}"); } #[test] diff --git a/exp/pecos-eeg/tests/beta_investigation.rs b/exp/pecos-eeg/tests/beta_investigation.rs index cce7af4cd..ec4d8b08e 100644 --- a/exp/pecos-eeg/tests/beta_investigation.rs +++ b/exp/pecos-eeg/tests/beta_investigation.rs @@ -5,17 +5,18 @@ //! Investigation: why off-diagonal beta terms don't fire for Z-basis. use pecos_core::gate_type::GateType; -use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; +use pecos_core::{Gate, GateAngles, GateParams, QubitId}; use pecos_eeg::Bm; use pecos_eeg::circuit::{NoiseModel, PropagatedEeg, analyze_expanded}; use pecos_eeg::eeg::EegType; use pecos_eeg::expand; use pecos_eeg::stabilizer::StabilizerGroup; +use pecos_simulators::{CliffordGateable, SparseStab}; fn gate(gt: GateType, qubits: &[usize]) -> Gate { Gate { gate_type: gt, - qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + qubits: qubits.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), @@ -104,8 +105,7 @@ fn test_zbasis_generator_labels() { if is_stab.is_some() || !orig_product.is_identity() { eprintln!( - " [{j},{k}] commute=true product_orig={:?} is_stab={:?}", - orig_product, is_stab + " [{j},{k}] commute=true product_orig={orig_product:?} is_stab={is_stab:?}" ); } } @@ -126,7 +126,6 @@ fn test_zbasis_stabilizer_group() { // Dump actual generators eprintln!("Stabilizer generators:"); // Run SparseStab manually to see generators - use pecos_simulators::{CliffordGateable, SparseStab}; let mut sim = SparseStab::with_seed(3, 0); for g in gates_pre { let qs: Vec = g.qubits.iter().copied().collect(); @@ -139,14 +138,12 @@ fn test_zbasis_stabilizer_group() { GateType::H => { sim.h(&qs); } - GateType::CX => { - if qs.len() >= 2 { - sim.cx(&[(qs[0], qs[1])]); - } + GateType::CX if qs.len() >= 2 => { + sim.cx(&[(qs[0], qs[1])]); } GateType::MZ => { let _r = sim.mz(&qs); - eprintln!(" MZ({:?})", qs); + eprintln!(" MZ({qs:?})"); } _ => {} } diff --git a/exp/pecos-eeg/tests/generator_trace.rs b/exp/pecos-eeg/tests/generator_trace.rs index e40cac1cd..1e0959ff8 100644 --- a/exp/pecos-eeg/tests/generator_trace.rs +++ b/exp/pecos-eeg/tests/generator_trace.rs @@ -4,10 +4,12 @@ //! Trace generator propagation for d=2 Z-basis surface code. //! Diagnose why D1 and D2 have identical EEG probabilities -//! when StateVec shows they should differ. +//! when `StateVec` shows they should differ. + +use std::collections::BTreeMap; use pecos_core::gate_type::GateType; -use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; +use pecos_core::{Gate, GateAngles, GateParams, QubitId}; use pecos_eeg::Bm; use pecos_eeg::circuit::{NoiseModel, analyze_expanded}; use pecos_eeg::dem_mapping::*; @@ -18,7 +20,7 @@ use pecos_eeg::stabilizer::StabilizerGroup; fn gate(gt: GateType, qubits: &[usize]) -> Gate { Gate { gate_type: gt, - qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + qubits: qubits.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), @@ -26,7 +28,7 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { } /// Build the d=2 Z-basis surface code circuit (2 rounds). -/// Matches what LogicalCircuitBuilder produces. +/// Matches what `LogicalCircuitBuilder` produces. fn build_d2_zbasis() -> Vec { vec![ // Init @@ -119,7 +121,7 @@ fn trace_d2_zbasis_generators() { eprintln!("\nD1 stabilizer: Z on aux q{aux_m0} and q{aux_m3} (ancilla 4 rounds 1&2)"); eprintln!("D2 stabilizer: Z on aux q{aux_m1} and q{aux_m4} (ancilla 5 rounds 1&2)"); - let _dets = vec![ + let _dets = [ Detector { id: 1, stabilizer: d1_stab.clone(), @@ -164,16 +166,15 @@ fn trace_d2_zbasis_generators() { eprintln!("\nD1 generators: {} (ancilla 4)", d1_gens.len()); for (label, coeff) in &d1_gens { - eprintln!(" {:?} coeff={:.6}", label, coeff); + eprintln!(" {label:?} coeff={coeff:.6}"); } eprintln!("\nD2 generators: {} (ancilla 5)", d2_gens.len()); for (label, coeff) in &d2_gens { - eprintln!(" {:?} coeff={:.6}", label, coeff); + eprintln!(" {label:?} coeff={coeff:.6}"); } // After BCH combination (same label → sum coefficients) - use std::collections::BTreeMap; let mut d1_bch: BTreeMap = BTreeMap::new(); let mut d2_bch: BTreeMap = BTreeMap::new(); for (l, c) in &d1_gens { @@ -185,12 +186,12 @@ fn trace_d2_zbasis_generators() { eprintln!("\nD1 after BCH: {} distinct labels", d1_bch.len()); for (l, c) in &d1_bch { - eprintln!(" {:?} rate={:.6}", l, c); + eprintln!(" {l:?} rate={c:.6}"); } eprintln!("\nD2 after BCH: {} distinct labels", d2_bch.len()); for (l, c) in &d2_bch { - eprintln!(" {:?} rate={:.6}", l, c); + eprintln!(" {l:?} rate={c:.6}"); } // Verify asymmetry in generator counts @@ -241,10 +242,8 @@ fn trace_d2_zbasis_generators() { GateType::H => { sim.h(&qs); } - GateType::CX => { - if qs.len() >= 2 { - sim.cx(&[(qs[0], qs[1])]); - } + GateType::CX if qs.len() >= 2 => { + sim.cx(&[(qs[0], qs[1])]); } GateType::MZ => { let _ = sim.mz(&qs); @@ -268,7 +267,7 @@ fn trace_d2_zbasis_generators() { std::iter::once(0usize), 0, ); - eprintln!("\nfind_pauli_sign(Z0) WITH MZ = {:?}", result); + eprintln!("\nfind_pauli_sign(Z0) WITH MZ = {result:?}"); // Try without MZ: skip measurements in stabilizer computation let mut sim2 = SparseStab::with_seed(7, 0); @@ -286,12 +285,9 @@ fn trace_d2_zbasis_generators() { GateType::H => { sim2.h(&qs); } - GateType::CX => { - if qs.len() >= 2 { - sim2.cx(&[(qs[0], qs[1])]); - } + GateType::CX if qs.len() >= 2 => { + sim2.cx(&[(qs[0], qs[1])]); } - GateType::MZ => { /* skip */ } _ => {} } } @@ -302,16 +298,12 @@ fn trace_d2_zbasis_generators() { std::iter::once(0usize), 0, ); - eprintln!("find_pauli_sign(Z0) WITHOUT MZ = {:?}", result2); + eprintln!("find_pauli_sign(Z0) WITHOUT MZ = {result2:?}"); // Check X0X1 without MZ - let result3 = stabs2.find_pauli_sign( - sim2.destabs(), - [0usize, 1].into_iter(), - std::iter::empty::(), - 0, - ); - eprintln!("find_pauli_sign(X0X1) WITHOUT MZ = {:?}", result3); + let result3 = + stabs2.find_pauli_sign(sim2.destabs(), [0usize, 1], std::iter::empty::(), 0); + eprintln!("find_pauli_sign(X0X1) WITHOUT MZ = {result3:?}"); } // Check: how many qubits in the stabilizer group? And test Z0Z1Z2Z3 diff --git a/exp/pecos-eeg/tests/stabilizer_audit.rs b/exp/pecos-eeg/tests/stabilizer_audit.rs index ee44464d4..dcc903cca 100644 --- a/exp/pecos-eeg/tests/stabilizer_audit.rs +++ b/exp/pecos-eeg/tests/stabilizer_audit.rs @@ -2,12 +2,12 @@ // // Licensed under the Apache License, Version 2.0 -//! Audit: does the StabilizerGroup correctly identify all stabilizers? +//! Audit: does the `StabilizerGroup` correctly identify all stabilizers? //! Test by generating all 2^n products of n generators and checking -//! that is_stabilizer returns Some for each. +//! that `is_stabilizer` returns Some for each. use pecos_core::gate_type::GateType; -use pecos_core::{Gate, GateAngles, GateParams, GateQubits, QubitId}; +use pecos_core::{Gate, GateAngles, GateParams, QubitId}; use pecos_eeg::Bm; use pecos_eeg::stabilizer::StabilizerGroup; use pecos_simulators::{CliffordGateable, SparseStab}; @@ -15,14 +15,14 @@ use pecos_simulators::{CliffordGateable, SparseStab}; fn gate(gt: GateType, qubits: &[usize]) -> Gate { Gate { gate_type: gt, - qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + qubits: qubits.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), } } -/// Extract generators as Bm from SparseStab. +/// Extract generators as Bm from `SparseStab`. fn extract_generators(sim: &SparseStab) -> Vec { let stabs = sim.stabs(); let n = stabs.num_generators(); @@ -34,8 +34,8 @@ fn extract_generators(sim: &SparseStab) -> Vec { gens } -/// Check that StabilizerGroup.is_stabilizer returns Some for ALL products -/// of the SparseStab generators (which are by definition in the group). +/// Check that `StabilizerGroup.is_stabilizer` returns Some for ALL products +/// of the `SparseStab` generators (which are by definition in the group). fn audit_stabilizer_group(label: &str, gates: &[Gate], num_qubits: usize) { let stab_group = StabilizerGroup::from_circuit(gates, num_qubits); @@ -70,15 +70,11 @@ fn audit_stabilizer_group(label: &str, gates: &[Gate], num_qubits: usize) { GateType::Z => { sim.z(&qs); } - GateType::CX => { - if qs.len() >= 2 { - sim.cx(&[(qs[0], qs[1])]); - } + GateType::CX if qs.len() >= 2 => { + sim.cx(&[(qs[0], qs[1])]); } - GateType::CZ => { - if qs.len() >= 2 { - sim.cz(&[(qs[0], qs[1])]); - } + GateType::CZ if qs.len() >= 2 => { + sim.cz(&[(qs[0], qs[1])]); } GateType::MZ => { sim.mz(&qs); @@ -101,9 +97,9 @@ fn audit_stabilizer_group(label: &str, gates: &[Gate], num_qubits: usize) { for mask in 0..max_subsets { let mut product = Bm::default(); - for i in 0..n { + for (i, generator) in generators.iter().enumerate().take(n) { if mask & (1 << i) != 0 { - product = product.multiply(&generators[i]); + product = product.multiply(generator); } } diff --git a/exp/pecos-eeg/tests/statevec_comparison.rs b/exp/pecos-eeg/tests/statevec_comparison.rs index 08d799d66..cff1ff58b 100644 --- a/exp/pecos-eeg/tests/statevec_comparison.rs +++ b/exp/pecos-eeg/tests/statevec_comparison.rs @@ -2,7 +2,7 @@ // // Licensed under the Apache License, Version 2.0 -//! Ground-truth comparison: EEG analytical DEM vs StateVec simulation. +//! Ground-truth comparison: EEG analytical DEM vs `StateVec` simulation. //! //! Uses Bell-state parity circuit where idle RZ noise creates detectable //! parity violations. Without noise, MZ parity is always even. @@ -11,7 +11,7 @@ use pecos_core::gate_type::GateType; use pecos_core::pauli::pauli_bitmask::BitmaskStorage; -use pecos_core::{Angle64, Gate, GateAngles, GateParams, GateQubits, QubitId}; +use pecos_core::{Angle64, Gate, GateAngles, GateParams, QubitId}; use pecos_eeg::Bm; use pecos_eeg::circuit::{NoiseModel, analyze_expanded}; use pecos_eeg::dem_mapping::{Detector, build_dem_with_stabilizers}; @@ -23,7 +23,7 @@ use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, StateVec}; fn gate(gt: GateType, qubits: &[usize]) -> Gate { Gate { gate_type: gt, - qubits: GateQubits::from_iter(qubits.iter().map(|&q| QubitId(q))), + qubits: qubits.iter().map(|&q| QubitId(q)).collect(), angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), @@ -34,6 +34,18 @@ fn qid(q: usize) -> QubitId { QubitId(q) } +fn u64_to_f64(value: u64) -> f64 { + f64::from(u32::try_from(value).expect("test sample count fits in u32")) +} + +fn usize_to_f64(value: usize) -> f64 { + f64::from(u32::try_from(value).expect("test dimension fits in u32")) +} + +fn bit_to_f64(value: usize) -> f64 { + f64::from(u8::try_from(value).expect("bit value fits in u8")) +} + // ============================================================ // Shared helpers for EEG analysis and StateVec simulation // ============================================================ @@ -186,9 +198,9 @@ fn test_eeg_vs_statevec_bell_parity() { } } - let sv_rate = odd_parity_count as f64 / num_shots as f64; - let sv_stderr = (sv_rate * (1.0 - sv_rate) / num_shots as f64).sqrt(); - let exact = (theta as f64).sin().powi(2); + let sv_rate = u64_to_f64(odd_parity_count) / f64::from(num_shots); + let sv_stderr = (sv_rate * (1.0 - sv_rate) / f64::from(num_shots)).sqrt(); + let exact = theta.sin().powi(2); eprintln!("theta = {theta}"); eprintln!("EEG: {eeg_prob:.6}"); @@ -269,9 +281,9 @@ fn test_eeg_vs_statevec_larger_angle() { } } - let sv_rate = odd_parity_count as f64 / num_shots as f64; - let sv_stderr = (sv_rate * (1.0 - sv_rate) / num_shots as f64).sqrt(); - let exact = (theta as f64).sin().powi(2); + let sv_rate = u64_to_f64(odd_parity_count) / f64::from(num_shots); + let sv_stderr = (sv_rate * (1.0 - sv_rate) / f64::from(num_shots)).sqrt(); + let exact = theta.sin().powi(2); eprintln!("theta = {theta}"); eprintln!("EEG: {eeg_prob:.6}"); @@ -295,7 +307,7 @@ fn test_eeg_vs_statevec_larger_angle() { /// Sweep theta for the Bell parity circuit. /// Exact answer: sin²(θ). EEG leading-order: θ². #[test] -#[ignore] +#[ignore = "benchmark sweep; run manually with --ignored --nocapture"] fn bench_bell_parity_theta_sweep() { let num_shots = 200_000; @@ -335,8 +347,8 @@ fn bench_bell_parity_theta_sweep() { } } - let sv = odd as f64 / num_shots as f64; - let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + let sv = u64_to_f64(odd) / f64::from(num_shots); + let se = (sv * (1.0 - sv) / f64::from(num_shots)).sqrt(); let exact = theta.sin().powi(2); let ratio = if exact > 1e-10 { eeg_prob / exact @@ -353,7 +365,7 @@ fn bench_bell_parity_theta_sweep() { /// Multi-round X-check: 2 data qubits, 1 ancilla, N rounds of X-check with reset. /// Data prepared in |++>, ancilla measures X0*X1 each round. #[test] -#[ignore] +#[ignore = "benchmark sweep; run manually with --ignored --nocapture"] fn bench_x_check_multi_round() { let num_shots = 200_000; @@ -392,7 +404,9 @@ fn bench_x_check_multi_round() { sim.h(&[qid(0)]); sim.h(&[qid(1)]); - for round in 0..num_rounds { + for (round, round_detection) in + round_detections.iter_mut().enumerate().take(num_rounds) + { sim.h(&[qid(2)]); sim.cx(&[(qid(2), qid(0))]); sim.rz(Angle64::from_radians(theta), &[qid(0)]); @@ -403,7 +417,7 @@ fn bench_x_check_multi_round() { sim.h(&[qid(2)]); let r = sim.mz(&[qid(2)]); if r[0].outcome { - round_detections[round] += 1; + *round_detection += 1; } if round < num_rounds - 1 { sim.pz(&[qid(2)]); @@ -413,12 +427,12 @@ fn bench_x_check_multi_round() { let sv_rates: Vec = round_detections .iter() - .map(|&d| d as f64 / num_shots as f64) + .map(|&d| u64_to_f64(d) / f64::from(num_shots)) .collect(); eprintln!("\nrounds={num_rounds}, theta={theta}:"); for r in 0..num_rounds { - let se = (sv_rates[r] * (1.0 - sv_rates[r]) / num_shots as f64).sqrt(); + let se = (sv_rates[r] * (1.0 - sv_rates[r]) / f64::from(num_shots)).sqrt(); let ratio = if sv_rates[r] > 1e-10 { eeg_probs[r] / sv_rates[r] } else { @@ -436,7 +450,7 @@ fn bench_x_check_multi_round() { /// Z-basis: data in |00>, Z-check measures Z0*Z1. Coherent RZ noise. /// Z errors commute with Z measurements, so the X-propagated components matter. #[test] -#[ignore] +#[ignore = "benchmark sweep; run manually with --ignored --nocapture"] fn bench_z_basis_check() { let num_shots = 200_000; @@ -492,8 +506,8 @@ fn bench_z_basis_check() { } } - let sv = det_count as f64 / num_shots as f64; - let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + let sv = u64_to_f64(det_count) / f64::from(num_shots); + let se = (sv * (1.0 - sv) / f64::from(num_shots)).sqrt(); let ratio = if sv > 1e-10 { eeg_prob / sv } else { f64::NAN }; eprintln!("{theta:>8.3} {eeg_prob:>10.6} {sv:>10.6} {se:>10.6} {ratio:>10.4}"); @@ -506,10 +520,10 @@ fn bench_z_basis_check() { /// Build an X-check repetition code circuit. /// -/// d data qubits, d-1 ancillas measuring X_i * X_{i+1} using +/// d data qubits, d-1 ancillas measuring `X_i` * X_{i+1} using /// H-CX-CX-H on ancilla (sensitive to Z errors from coherent RZ noise). /// `num_rounds` syndrome extraction rounds with reset. -/// Returns (gates, num_qubits, ancilla indices). +/// Returns (gates, `num_qubits`, ancilla indices). fn build_repetition_code(d: usize, num_rounds: usize) -> (Vec, usize, Vec) { let num_data = d; let num_ancilla = d - 1; @@ -564,9 +578,9 @@ fn build_repetition_code(d: usize, num_rounds: usize) -> (Vec, usize, Vec< (gates, num_qubits, ancillas) } -/// Repetition code: compare EEG (forward), Heisenberg (backward), and StateVec. +/// Repetition code: compare EEG (forward), Heisenberg (backward), and `StateVec`. #[test] -#[ignore] +#[ignore = "benchmark sweep; run manually with --ignored --nocapture"] fn bench_repetition_code_comparison() { use pecos_eeg::dem_mapping::EegConfig; use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; @@ -673,14 +687,12 @@ fn bench_repetition_code_comparison() { let anc_qubits: Vec<_> = ancillas.iter().map(|&a| qid(a)).collect(); sim.h(&anc_qubits); - for i in 0..num_ancilla { - let anc = ancillas[i]; + for (i, &anc) in ancillas.iter().enumerate().take(num_ancilla) { sim.cx(&[(qid(anc), qid(i))]); sim.rz(Angle64::from_radians(theta), &[qid(anc)]); sim.rz(Angle64::from_radians(theta), &[qid(i)]); } - for i in 0..num_ancilla { - let anc = ancillas[i]; + for (i, &anc) in ancillas.iter().enumerate().take(num_ancilla) { sim.cx(&[(qid(anc), qid(i + 1))]); sim.rz(Angle64::from_radians(theta), &[qid(anc)]); sim.rz(Angle64::from_radians(theta), &[qid(i + 1)]); @@ -689,8 +701,8 @@ fn bench_repetition_code_comparison() { sim.h(&anc_qubits); // Measure ancillas - for i in 0..num_ancilla { - let r = sim.mz(&[qid(ancillas[i])]); + for &anc in ancillas.iter().take(num_ancilla) { + let r = sim.mz(&[qid(anc)]); meas_outcomes.push(r[0].outcome); } @@ -718,8 +730,8 @@ fn bench_repetition_code_comparison() { "Det", "EEG", "Heisen", "StateVec", "SV_err", "H/SV" ); for det_idx in 0..num_detectors { - let sv_rate = sv_counts[det_idx] as f64 / num_shots as f64; - let sv_err = (sv_rate * (1.0 - sv_rate) / num_shots as f64).sqrt(); + let sv_rate = u64_to_f64(sv_counts[det_idx]) / f64::from(num_shots); + let sv_err = (sv_rate * (1.0 - sv_rate) / f64::from(num_shots)).sqrt(); let ratio = if sv_rate > 1e-10 { heis_probs[det_idx] / sv_rate } else { @@ -736,13 +748,13 @@ fn bench_repetition_code_comparison() { } } -/// KEY DIAGNOSTIC: Compare original-circuit StateVec, expanded-circuit StateVec, +/// KEY DIAGNOSTIC: Compare original-circuit `StateVec`, expanded-circuit `StateVec`, /// and Heisenberg for the simplest failing case (weight-2, 2 rounds, 3 qubits). /// /// If expanded SV matches original SV: expansion is correct, Heisenberg has a bug. /// If expanded SV differs: expansion is wrong. #[test] -#[ignore] +#[ignore = "benchmark sweep; run manually with --ignored --nocapture"] fn bench_expansion_equivalence() { use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; @@ -778,7 +790,7 @@ fn bench_expansion_equivalence() { ); eprintln!("Measurement map: {:?}", expanded.measurement_qubit); for (i, g) in expanded.gates.iter().enumerate() { - let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + let qs: Vec = g.qubits.iter().map(pecos_core::QubitId::index).collect(); eprintln!(" [{i:2}] {:?}({qs:?})", g.gate_type); } @@ -793,7 +805,7 @@ fn bench_expansion_equivalence() { for _ in 0..num_shots { sim.pz(&[qid(0), qid(1), qid(2)]); let mut outs = [false; 2]; - for r in 0..2 { + for (r, out) in outs.iter_mut().enumerate() { sim.h(&[qid(2)]); sim.cx(&[(qid(2), qid(0))]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); @@ -802,7 +814,7 @@ fn bench_expansion_equivalence() { sim.rz(Angle64::from_radians(theta), &[qid(1)]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.h(&[qid(2)]); - outs[r] = sim.mz(&[qid(2)])[0].outcome; + *out = sim.mz(&[qid(2)])[0].outcome; if r == 0 { sim.pz(&[qid(2)]); } @@ -812,7 +824,7 @@ fn bench_expansion_equivalence() { } } } - let sv_orig = orig_det as f64 / num_shots as f64; + let sv_orig = u64_to_f64(orig_det) / f64::from(num_shots); // --- StateVec on EXPANDED circuit (no mid-circuit measurements) --- let mut exp_det = 0u64; @@ -825,7 +837,7 @@ fn bench_expansion_equivalence() { sim.pz(&all_q); for (i, g) in expanded.gates.iter().enumerate() { - let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + let qs: Vec = g.qubits.iter().map(pecos_core::QubitId::index).collect(); // Skip expansion gates for noise (same logic as Heisenberg) let is_exp_gate = { @@ -856,23 +868,19 @@ fn bench_expansion_equivalence() { sim.h(&[qid(q)]); } } - pecos_core::gate_type::GateType::CX => { - if qs.len() >= 2 { - sim.cx(&[(qid(qs[0]), qid(qs[1]))]); - } - } - pecos_core::gate_type::GateType::MZ => { - // Final measurement — handled below + pecos_core::gate_type::GateType::CX if qs.len() >= 2 => { + sim.cx(&[(qid(qs[0]), qid(qs[1]))]); } _ => {} } // Add noise after non-expansion CX gates - if !is_exp_gate && (g.gate_type == pecos_core::gate_type::GateType::CX) { - if qs.len() >= 2 { - sim.rz(Angle64::from_radians(theta), &[qid(qs[0])]); - sim.rz(Angle64::from_radians(theta), &[qid(qs[1])]); - } + if !is_exp_gate + && (g.gate_type == pecos_core::gate_type::GateType::CX) + && qs.len() >= 2 + { + sim.rz(Angle64::from_radians(theta), &[qid(qs[0])]); + sim.rz(Angle64::from_radians(theta), &[qid(qs[1])]); } } @@ -886,13 +894,13 @@ fn bench_expansion_equivalence() { } } } - let sv_exp = exp_det as f64 / num_shots as f64; + let sv_exp = u64_to_f64(exp_det) / f64::from(num_shots); // Exact analytical let exact = (2.0 - (6.0 * theta).cos() - (2.0 * theta).cos()) / 4.0; - let se_orig = (sv_orig * (1.0 - sv_orig) / num_shots as f64).sqrt(); - let se_exp = (sv_exp * (1.0 - sv_exp) / num_shots as f64).sqrt(); + let se_orig = (sv_orig * (1.0 - sv_orig) / f64::from(num_shots)).sqrt(); + let se_exp = (sv_exp * (1.0 - sv_exp) / f64::from(num_shots)).sqrt(); eprintln!("\nResults:"); eprintln!(" Exact analytical: {exact:.6}"); @@ -907,13 +915,13 @@ fn bench_expansion_equivalence() { /// on the expanded circuit. This bypasses the Pauli-tracking backward walk entirely. /// /// The detection probability is: -/// p = (1 - <0...0| O_backward |0...0>) / 2 -/// where O_backward = E_1† ... E_n†(D) +/// p = (1 - <0...0| `O_backward` |0...0>) / 2 +/// where `O_backward` = `E_1`† ... `E_n†(D)` /// -/// We compute O_backward as a 2^n × 2^n matrix by multiplying the adjoint +/// We compute `O_backward` as a 2^n × 2^n matrix by multiplying the adjoint /// of each gate/noise channel, then evaluate the diagonal element. #[test] -#[ignore] +#[ignore = "benchmark sweep; run manually with --ignored --nocapture"] fn bench_matrix_heisenberg() { use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; @@ -997,18 +1005,13 @@ fn bench_matrix_heisenberg() { for idx in (0..expanded.gates.len()).rev() { let g = &expanded.gates[idx]; - let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + let qs: Vec = g.qubits.iter().map(pecos_core::QubitId::index).collect(); // Apply noise adjoint (if not expansion gate) - if !exp_gates_set.contains(&idx) { - match g.gate_type { - pecos_core::gate_type::GateType::CX => { - // idle_rz on both qubits - for &q in &qs { - apply_rz_adjoint(&mut obs_re, &mut obs_im, q, theta, n); - } - } - _ => {} + if !exp_gates_set.contains(&idx) && g.gate_type == pecos_core::gate_type::GateType::CX { + // idle_rz on both qubits + for &q in &qs { + apply_rz_adjoint(&mut obs_re, &mut obs_im, q, theta, n); } } @@ -1057,14 +1060,12 @@ fn bench_matrix_heisenberg() { for idx in (0..expanded.gates.len()).rev() { let g = &expanded.gates[idx]; - let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + let qs: Vec = g.qubits.iter().map(pecos_core::QubitId::index).collect(); let is_exp = exp_gates_set.contains(&idx); - if !is_exp { - if g.gate_type == pecos_core::gate_type::GateType::CX && qs.len() >= 2 { - for &q in &qs { - apply_rz_adjoint(&mut tr_re, &mut tr_im, q, theta, n); - } + if !is_exp && g.gate_type == pecos_core::gate_type::GateType::CX && qs.len() >= 2 { + for &q in &qs { + apply_rz_adjoint(&mut tr_re, &mut tr_im, q, theta, n); } } @@ -1112,9 +1113,9 @@ fn apply_rz_adjoint(re: &mut [f64], im: &mut [f64], q: usize, theta: f64, n: usi // New O[i,j] = e^{i(b_i - b_j)θ/2} · O[i,j] // where b_i = bit q of i (0 → phase -θ/2, 1 → phase +θ/2) for i in 0..dim { - let bi = ((i >> q) & 1) as f64; // 0 or 1 + let bi = bit_to_f64((i >> q) & 1); // 0 or 1 for j in 0..dim { - let bj = ((j >> q) & 1) as f64; + let bj = bit_to_f64((j >> q) & 1); let phase = (bi - bj) * theta; // phase angle if phase.abs() < 1e-20 { continue; @@ -1141,15 +1142,15 @@ fn apply_pz_adjoint(re: &mut [f64], im: &mut [f64], q: usize, n: usize) { for j in 0..dim { let jq = (j >> q) & 1; let idx = i * dim + j; - if iq != jq { - re[idx] = 0.0; - im[idx] = 0.0; - } else { + if iq == jq { let i0 = i & !mask; let j0 = j & !mask; let idx0 = i0 * dim + j0; re[idx] = re[idx0]; im[idx] = im[idx0]; + } else { + re[idx] = 0.0; + im[idx] = 0.0; } } } @@ -1199,7 +1200,7 @@ fn apply_h_adjoint(re: &mut [f64], im: &mut [f64], q: usize, n: usize) { let ia = if a == 0 { i0 } else { i1 }; let jb = if b == 0 { j0 } else { j1 }; let idx = ia * dim + jb; - let sign = if (iq * a + b * jq) % 2 == 0 { + let sign = if (iq * a + b * jq).is_multiple_of(2) { 1.0 } else { -1.0 @@ -1244,7 +1245,7 @@ fn apply_cx_adjoint(re: &mut [f64], im: &mut [f64], control: usize, target: usiz /// /// Enable one noise source at a time and compare matrix vs backward walk. #[test] -#[ignore] +#[ignore = "benchmark sweep; run manually with --ignored --nocapture"] fn bench_per_noise_attribution() { use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; @@ -1305,7 +1306,7 @@ fn bench_per_noise_attribution() { // Process gates in reverse, only applying noise for the specified source for idx in (0..expanded.gates.len()).rev() { let g = &expanded.gates[idx]; - let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + let qs: Vec = g.qubits.iter().map(pecos_core::QubitId::index).collect(); // Noise: only the specified source if idx == gate_idx { @@ -1347,7 +1348,7 @@ fn bench_per_noise_attribution() { } for idx in (0..expanded.gates.len()).rev() { let g = &expanded.gates[idx]; - let qs: Vec = g.qubits.iter().map(|q| q.index()).collect(); + let qs: Vec = g.qubits.iter().map(pecos_core::QubitId::index).collect(); if g.gate_type == pecos_core::gate_type::GateType::CX && qs.len() >= 2 { // Check if expansion gate let is_exp = idx > 0 @@ -1389,7 +1390,7 @@ fn bench_per_noise_attribution() { /// Isolate weight-2 vs weight-4 X-check, single vs multi-round. #[test] -#[ignore] +#[ignore = "benchmark sweep; run manually with --ignored --nocapture"] fn bench_weight_isolation() { use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; @@ -1430,8 +1431,8 @@ fn bench_weight_isolation() { det += 1; } } - let sv = det as f64 / num_shots as f64; - let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + let sv = u64_to_f64(det) / f64::from(num_shots); + let se = (sv * (1.0 - sv) / f64::from(num_shots)).sqrt(); eprintln!( "Wt-2 1rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", if sv > 1e-10 { h_p / sv } else { f64::NAN } @@ -1464,7 +1465,7 @@ fn bench_weight_isolation() { for _ in 0..num_shots { sim.pz(&[qid(0), qid(1), qid(2)]); let mut outs = [false; 2]; - for r in 0..2 { + for (r, out) in outs.iter_mut().enumerate() { sim.h(&[qid(2)]); sim.cx(&[(qid(2), qid(0))]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); @@ -1473,7 +1474,7 @@ fn bench_weight_isolation() { sim.rz(Angle64::from_radians(theta), &[qid(1)]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.h(&[qid(2)]); - outs[r] = sim.mz(&[qid(2)])[0].outcome; + *out = sim.mz(&[qid(2)])[0].outcome; if r == 0 { sim.pz(&[qid(2)]); } @@ -1482,8 +1483,8 @@ fn bench_weight_isolation() { det += 1; } } - let sv = det as f64 / num_shots as f64; - let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + let sv = u64_to_f64(det) / f64::from(num_shots); + let se = (sv * (1.0 - sv) / f64::from(num_shots)).sqrt(); eprintln!( "Wt-2 2rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", if sv > 1e-10 { h_p / sv } else { f64::NAN } @@ -1524,8 +1525,8 @@ fn bench_weight_isolation() { det += 1; } } - let sv = det as f64 / num_shots as f64; - let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + let sv = u64_to_f64(det) / f64::from(num_shots); + let se = (sv * (1.0 - sv) / f64::from(num_shots)).sqrt(); eprintln!( "Wt-4 1rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", if sv > 1e-10 { h_p / sv } else { f64::NAN } @@ -1564,7 +1565,7 @@ fn bench_weight_isolation() { for _ in 0..num_shots { sim.pz(&[qid(0), qid(1), qid(2), qid(3), qid(4)]); let mut outs = [false; 2]; - for r in 0..2 { + for (r, out) in outs.iter_mut().enumerate() { sim.h(&[qid(4)]); for &d in &[0usize, 1, 2, 3] { sim.cx(&[(qid(4), qid(d))]); @@ -1572,7 +1573,7 @@ fn bench_weight_isolation() { sim.rz(Angle64::from_radians(theta), &[qid(d)]); } sim.h(&[qid(4)]); - outs[r] = sim.mz(&[qid(4)])[0].outcome; + *out = sim.mz(&[qid(4)])[0].outcome; if r == 0 { sim.pz(&[qid(4)]); } @@ -1581,8 +1582,8 @@ fn bench_weight_isolation() { det += 1; } } - let sv = det as f64 / num_shots as f64; - let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + let sv = u64_to_f64(det) / f64::from(num_shots); + let se = (sv * (1.0 - sv) / f64::from(num_shots)).sqrt(); eprintln!( "Wt-4 2rnd: H={h_p:.6} SV={sv:.6}+/-{se:.6} H/SV={:.4}", if sv > 1e-10 { h_p / sv } else { f64::NAN } @@ -1633,7 +1634,7 @@ fn bench_weight_isolation() { for _ in 0..num_shots { sim.pz(&[qid(0), qid(1), qid(2), qid(3), qid(4)]); let mut outs = [false; 4]; // [r0a0, r0a1, r1a0, r1a1] - for r in 0..2 { + for (r, out_pair) in outs.chunks_mut(2).enumerate() { sim.h(&[qid(3), qid(4)]); sim.cx(&[(qid(3), qid(0))]); sim.rz(Angle64::from_radians(theta), &[qid(3)]); @@ -1648,8 +1649,8 @@ fn bench_weight_isolation() { sim.rz(Angle64::from_radians(theta), &[qid(4)]); sim.rz(Angle64::from_radians(theta), &[qid(2)]); sim.h(&[qid(3), qid(4)]); - outs[r * 2] = sim.mz(&[qid(3)])[0].outcome; - outs[r * 2 + 1] = sim.mz(&[qid(4)])[0].outcome; + out_pair[0] = sim.mz(&[qid(3)])[0].outcome; + out_pair[1] = sim.mz(&[qid(4)])[0].outcome; if r == 0 { sim.pz(&[qid(3), qid(4)]); } @@ -1661,10 +1662,10 @@ fn bench_weight_isolation() { a1 += 1; } } - let sv0 = a0 as f64 / num_shots as f64; - let sv1 = a1 as f64 / num_shots as f64; - let se0 = (sv0 * (1.0 - sv0) / num_shots as f64).sqrt(); - let se1 = (sv1 * (1.0 - sv1) / num_shots as f64).sqrt(); + let sv0 = u64_to_f64(a0) / f64::from(num_shots); + let sv1 = u64_to_f64(a1) / f64::from(num_shots); + let se0 = (sv0 * (1.0 - sv0) / f64::from(num_shots)).sqrt(); + let se1 = (sv1 * (1.0 - sv1) / f64::from(num_shots)).sqrt(); eprintln!( "Shared A0: H={h_a0:.6} SV={sv0:.6}+/-{se0:.6} H/SV={:.4}", if sv0 > 1e-10 { h_a0 / sv0 } else { f64::NAN } @@ -1686,7 +1687,7 @@ fn bench_weight_isolation() { /// since boundary detectors (ancilla 0/last) only couple to 2 CX gates while /// bulk detectors (middle ancillas) couple to 4, seeing more noise sources. #[test] -#[ignore] +#[ignore = "benchmark sweep; run manually with --ignored --nocapture"] fn bench_heisenberg_scaling() { use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; use std::time::Instant; @@ -1731,14 +1732,14 @@ fn bench_heisenberg_scaling() { ); let elapsed_ms = start.elapsed().as_secs_f64() * 1000.0; - eprintln!(" {:>6} {prob:>18.10} {elapsed_ms:>12.2}", i); + eprintln!(" {i:>6} {prob:>18.10} {elapsed_ms:>12.2}"); max_prob = max_prob.max(prob); max_ms = max_ms.max(elapsed_ms); total_ms += elapsed_ms; } - let per_det = total_ms / num_detectors as f64; + let per_det = total_ms / usize_to_f64(num_detectors); eprintln!( "{d:>4} {num_qubits:>10} {:>14} {num_detectors:>6} {max_prob:>18.10} {max_ms:>12.2} {total_ms:>12.2} {per_det:>12.2}", expanded.num_qubits @@ -1791,7 +1792,7 @@ fn bench_heisenberg_scaling() { ); let elapsed_ms = start.elapsed().as_secs_f64() * 1000.0; - eprintln!(" R{}A{} {prob:>18.10} {elapsed_ms:>12.2}", round, i); + eprintln!(" R{round}A{i} {prob:>18.10} {elapsed_ms:>12.2}"); max_prob = max_prob.max(prob); max_ms = max_ms.max(elapsed_ms); @@ -1799,7 +1800,7 @@ fn bench_heisenberg_scaling() { } } - let per_det = total_ms / num_detectors as f64; + let per_det = total_ms / usize_to_f64(num_detectors); eprintln!( "{num_rounds:>6} {num_qubits:>10} {:>14} {num_detectors:>6} {max_prob:>18.10} {max_ms:>12.2} {total_ms:>12.2} {per_det:>12.2}", expanded.num_qubits @@ -1813,12 +1814,12 @@ fn bench_heisenberg_scaling() { /// (measurement bit-flip). The Heisenberg walk handles both H-type and /// S-type generators in a single backward pass. /// -/// StateVec applies identical noise: RZ(theta) on both qubits after each -/// CX, and flips the MZ outcome with probability p_meas. +/// `StateVec` applies identical noise: RZ(theta) on both qubits after each +/// CX, and flips the MZ outcome with probability `p_meas`. /// /// Detector: round-comparison (meas[0] XOR meas[1]). #[test] -#[ignore] +#[ignore = "benchmark sweep; run manually with --ignored --nocapture"] fn bench_combined_noise() { use pecos_eeg::heisenberg::heisenberg_detection_probability_from_circuit; use pecos_random::PecosRng; @@ -1885,7 +1886,7 @@ fn bench_combined_noise() { for _ in 0..num_shots { sim.pz(&[qid(0), qid(1), qid(2)]); let mut outs = [false; 2]; - for r in 0..2 { + for (r, out_slot) in outs.iter_mut().enumerate() { sim.h(&[qid(2)]); // CX(2,0) + idle RZ noise sim.cx(&[(qid(2), qid(0))]); @@ -1901,7 +1902,7 @@ fn bench_combined_noise() { if rng.check_probability(meas_threshold) { outcome = !outcome; } - outs[r] = outcome; + *out_slot = outcome; if r == 0 { sim.pz(&[qid(2)]); } @@ -1910,8 +1911,8 @@ fn bench_combined_noise() { det += 1; } } - let sv = det as f64 / num_shots as f64; - let se = (sv * (1.0 - sv) / num_shots as f64).sqrt(); + let sv = u64_to_f64(det) / f64::from(num_shots); + let se = (sv * (1.0 - sv) / f64::from(num_shots)).sqrt(); let ratio = if sv > 1e-10 { h_p / sv } else { f64::NAN }; eprintln!("Heisenberg (combined): {h_p:.6}"); @@ -1942,7 +1943,7 @@ fn bench_combined_noise() { for _ in 0..num_shots { sim.pz(&[qid(0), qid(1), qid(2)]); let mut os = [false; 2]; - for r in 0..2 { + for (r, out_slot) in os.iter_mut().enumerate() { sim.h(&[qid(2)]); sim.cx(&[(qid(2), qid(0))]); sim.rz(Angle64::from_radians(idle_rz), &[qid(2)]); @@ -1955,7 +1956,7 @@ fn bench_combined_noise() { if rng.check_probability(pm_threshold) { out = !out; } - os[r] = out; + *out_slot = out; if r == 0 { sim.pz(&[qid(2)]); } @@ -1964,8 +1965,8 @@ fn bench_combined_noise() { d += 1; } } - let s = d as f64 / num_shots as f64; - let e = (s * (1.0 - s) / num_shots as f64).sqrt(); + let s = u64_to_f64(d) / f64::from(num_shots); + let e = (s * (1.0 - s) / f64::from(num_shots)).sqrt(); let r = if s > 1e-10 { hp / s } else { f64::NAN }; eprintln!("{pm:>8.4} {hp:>10.6} {s:>10.6} {e:>10.6} {r:>10.4}"); } diff --git a/exp/pecos-eeg/tests/strong_sim_validation.rs b/exp/pecos-eeg/tests/strong_sim_validation.rs index ed52b050c..b6e3434c0 100644 --- a/exp/pecos-eeg/tests/strong_sim_validation.rs +++ b/exp/pecos-eeg/tests/strong_sim_validation.rs @@ -9,7 +9,7 @@ use pecos_eeg::circuit::PropagatedEeg; use pecos_eeg::eeg::EegType; use pecos_eeg::strong_sim::outcome_probability; -/// H-type correction: |0⟩ with H_X gives p(1) = h² at leading order. +/// H-type correction: |0⟩ with `H_X` gives p(1) = h² at leading order. /// Cross-check: exact p(1) = sin²(h). #[test] fn test_h_correction_matches_exact() { diff --git a/exp/pecos-neo/src/runner.rs b/exp/pecos-neo/src/runner.rs index 64a2e3720..08094abfe 100644 --- a/exp/pecos-neo/src/runner.rs +++ b/exp/pecos-neo/src/runner.rs @@ -3153,14 +3153,13 @@ mod tests { .iter() .zip(expected.iter()) .find(|(a, e)| a.norm() > TOLERANCE || e.norm() > TOLERANCE) - .map(|(a, e)| { + .map_or(Complex64::new(1.0, 0.0), |(a, e)| { assert!( a.norm() > TOLERANCE && e.norm() > TOLERANCE, "{label}: support differs, actual={a:?}, expected={e:?}" ); *a / *e - }) - .unwrap_or(Complex64::new(1.0, 0.0)); + }); for (idx, (a, e)) in actual.iter().zip(expected.iter()).enumerate() { let diff = (*a - phase * *e).norm(); diff --git a/python/quantum-pecos/src/pecos/qec/analysis.py b/python/quantum-pecos/src/pecos/qec/analysis.py index 6ce03c335..2f22f1f8e 100644 --- a/python/quantum-pecos/src/pecos/qec/analysis.py +++ b/python/quantum-pecos/src/pecos/qec/analysis.py @@ -10,7 +10,9 @@ from __future__ import annotations +import json import math +from itertools import combinations from typing import TYPE_CHECKING if TYPE_CHECKING: @@ -260,12 +262,7 @@ def detector_flip_matrix( for events in detector_events: # Determine which detectors fired - if len(events) == n: - # Full binary vector - fired = [i for i in range(n) if events[i]] - else: - # Sparse list of detector indices - fired = list(events) + fired = [i for i in range(n) if events[i]] if len(events) == n else list(events) for a in fired: m[a * n + a] += inv_shots # diagonal @@ -300,10 +297,7 @@ def detector_flip_matrices_by_round( num_rounds = (num_detectors + detectors_per_round - 1) // detectors_per_round shots = len(detector_events) if shots == 0: - return [ - [[0.0] * detectors_per_round for _ in range(detectors_per_round)] - for _ in range(num_rounds) - ] + return [[[0.0] * detectors_per_round for _ in range(detectors_per_round)] for _ in range(num_rounds)] inv_shots = 1.0 / shots half_inv = 0.5 * inv_shots @@ -313,10 +307,7 @@ def detector_flip_matrices_by_round( matrices = [[0.0] * (k * k) for _ in range(num_rounds)] for events in detector_events: - if len(events) == num_detectors: - fired = [i for i in range(num_detectors) if events[i]] - else: - fired = list(events) + fired = [i for i in range(num_detectors) if events[i]] if len(events) == num_detectors else list(events) # Bin by round round_fired: dict[int, list[int]] = {} @@ -336,10 +327,7 @@ def detector_flip_matrices_by_round( mat[a * k + b] += half_inv mat[b * k + a] += half_inv - return [ - [matrices[r][i * k : (i + 1) * k] for i in range(k)] - for r in range(num_rounds) - ] + return [[matrices[r][i * k : (i + 1) * k] for i in range(k)] for r in range(num_rounds)] def compare_flip_matrices( @@ -414,8 +402,6 @@ def detector_k_body_rates( Returns: Dict mapping detector index tuples to joint firing rates. """ - from itertools import combinations - shots = len(detector_events) if shots == 0: return {} @@ -424,10 +410,7 @@ def detector_k_body_rates( rates: dict[tuple[int, ...], float] = {} for events in detector_events: - if len(events) == num_detectors: - fired = [i for i in range(num_detectors) if events[i]] - else: - fired = sorted(events) + fired = [i for i in range(num_detectors) if events[i]] if len(events) == num_detectors else sorted(events) for k in range(1, min(max_order, len(fired)) + 1): for combo in combinations(fired, k): @@ -461,8 +444,6 @@ def detector_k_body_rates_by_round( List of dicts, one per round, mapping local detector index tuples to joint firing rates. """ - from itertools import combinations - k = detectors_per_round num_rounds = (num_detectors + k - 1) // k shots = len(detector_events) @@ -473,10 +454,7 @@ def detector_k_body_rates_by_round( round_rates: list[dict[tuple[int, ...], float]] = [{} for _ in range(num_rounds)] for events in detector_events: - if len(events) == num_detectors: - fired = [i for i in range(num_detectors) if events[i]] - else: - fired = sorted(events) + fired = [i for i in range(num_detectors) if events[i]] if len(events) == num_detectors else sorted(events) # Bin fired detectors by round round_fired: dict[int, list[int]] = {} @@ -600,8 +578,6 @@ def empirical_correlation_table( for indices, prob in table: print(f"P({indices}) = {prob:.6f}") """ - import json - from pecos_rslib_exp import ( meas_sampling, sim_neo, @@ -610,35 +586,22 @@ def empirical_correlation_table( ) if backend == "meas_sampling": - results = ( - sim_neo(tick_circuit) - .quantum(meas_sampling()) - .noise(noise_builder) - .shots(shots) - .seed(seed) - .run() - ) + results = sim_neo(tick_circuit).quantum(meas_sampling()).noise(noise_builder).shots(shots).seed(seed).run() elif backend in ("stabilizer", "statevec"): backend_obj = stabilizer() if backend == "stabilizer" else statevec() - results = ( - sim_neo(tick_circuit) - .quantum(backend_obj) - .noise(noise_builder) - .shots(shots) - .seed(seed) - .run() - ) + results = sim_neo(tick_circuit).quantum(backend_obj).noise(noise_builder).shots(shots).seed(seed).run() else: supported = "'stabilizer', 'statevec', 'meas_sampling'" + msg = f"Unknown backend {backend!r}. Supported: {supported}." raise ValueError( - f"Unknown backend {backend!r}. Supported: {supported}." + msg, ) det_json = json.loads(tick_circuit.get_meta("detectors")) obs_json_str = tick_circuit.get_meta("observables") obs_json = json.loads(obs_json_str) if obs_json_str else [] num_meas = int(tick_circuit.get_meta("num_measurements")) - num_dets = len(det_json) + len(det_json) # Extract fired detectors and observables per shot fired_per_shot: list[list[int]] = [] @@ -668,8 +631,6 @@ def empirical_correlation_table( obs_per_shot.append(obs_fired) # Compute detector k-body rates with string labels - from itertools import combinations - inv_shots = 1.0 / shots rates: dict[tuple[str, ...], float] = {} @@ -686,7 +647,7 @@ def empirical_correlation_table( rates[key] = rates.get(key, 0.0) + inv_shots # Detector-observable pairwise: P(Di AND Lj) - for fired, obs_fired in zip(fired_per_shot, obs_per_shot): + for fired, obs_fired in zip(fired_per_shot, obs_per_shot, strict=False): for d in fired: for o in obs_fired: key = (f"D{d}", f"L{o}") @@ -726,12 +687,13 @@ def fit_dem_from_simulation( Returns: Stim-format DEM string with simulation-fitted probabilities. """ - import json - from itertools import combinations + if max_correlation_order < 1: + msg = "max_correlation_order must be at least 1" + raise ValueError(msg) from pecos_rslib.qec import ( - DemBuilder, DagFaultAnalyzer, + DemBuilder, fit_dem_to_marginals, mechanisms_to_dem_string, ) @@ -752,14 +714,14 @@ def fit_dem_from_simulation( builder = builder.with_detectors_json(tick_circuit.get_meta("detectors")) builder = builder.with_observables_json(tick_circuit.get_meta("observables")) builder = builder.with_num_measurements( - int(tick_circuit.get_meta("num_measurements")) + int(tick_circuit.get_meta("num_measurements")), ) dem = builder.build() dem_str = dem.to_string() mechs: list[tuple[float, list[int], list[int]]] = [] - for line in dem_str.strip().split("\n"): - line = line.strip() + for raw_line in dem_str.strip().split("\n"): + line = raw_line.strip() if line.startswith("error("): pe = line.index(")") prob = float(line[6:pe]) @@ -774,27 +736,14 @@ def fit_dem_from_simulation( num_dets = len(det_json) if backend == "meas_sampling": - results = ( - sim_neo(tick_circuit) - .quantum(meas_sampling()) - .noise(noise_builder) - .shots(shots) - .seed(seed) - .run() - ) + results = sim_neo(tick_circuit).quantum(meas_sampling()).noise(noise_builder).shots(shots).seed(seed).run() elif backend in ("stabilizer", "statevec"): backend_obj = stabilizer() if backend == "stabilizer" else statevec() - results = ( - sim_neo(tick_circuit) - .quantum(backend_obj) - .noise(noise_builder) - .shots(shots) - .seed(seed) - .run() - ) + results = sim_neo(tick_circuit).quantum(backend_obj).noise(noise_builder).shots(shots).seed(seed).run() else: supported = "'stabilizer', 'statevec', 'meas_sampling'" - raise ValueError(f"Unknown backend {backend!r}. Supported: {supported}.") + msg = f"Unknown backend {backend!r}. Supported: {supported}." + raise ValueError(msg) inv_shots = 1.0 / shots emp_marginals = [0.0] * num_dets @@ -844,7 +793,7 @@ def build_adaptive_dem( # Pure stochastic: from_circuit is best from pecos_rslib.qec import DemSampler - sampler = DemSampler.from_circuit( + DemSampler.from_circuit( tick_circuit, p1=noise_params.get("p1", 0.0), p2=noise_params.get("p2", 0.0), @@ -856,18 +805,16 @@ def build_adaptive_dem( table = exact_correlation_table(tick_circuit, **noise_params, max_order=max_order) # Return a minimal JSON with correlations - import json as _json - - json_out = _json.dumps({ - "correlations": [ - {"nodes": list(labels), "probability": prob} - for labels, prob in table - ], - }, indent=2) + json_out = json.dumps( + { + "correlations": [{"nodes": list(labels), "probability": prob} for labels, prob in table], + }, + indent=2, + ) # Get DEM string from the sampler's internal DEM dem_str = "" # from_circuit doesn't expose DEM string directly # Rebuild via DemBuilder - from pecos_rslib.qec import DemBuilder, DagFaultAnalyzer + from pecos_rslib.qec import DagFaultAnalyzer, DemBuilder dag = tick_circuit.to_dag_circuit() analyzer = DagFaultAnalyzer(dag) @@ -882,7 +829,7 @@ def build_adaptive_dem( builder = builder.with_detectors_json(tick_circuit.get_meta("detectors")) builder = builder.with_observables_json(tick_circuit.get_meta("observables")) builder = builder.with_num_measurements( - int(tick_circuit.get_meta("num_measurements")) + int(tick_circuit.get_meta("num_measurements")), ) dem = builder.build() dem_str = dem.to_string() @@ -893,5 +840,8 @@ def build_adaptive_dem( from pecos_rslib_exp import noise_characterization return noise_characterization( - tick_circuit, **noise_params, max_order=max_order, prune=prune, + tick_circuit, + **noise_params, + max_order=max_order, + prune=prune, ) diff --git a/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py b/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py index d775f1696..178baa68f 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py +++ b/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py @@ -2323,8 +2323,8 @@ def generate_dem_from_tick_circuit_via_autodetection( tracked operators are represented with PECOS `pecos_tracked_op` metadata lines. """ - from collections import defaultdict import json + from collections import defaultdict from pecos.qec import PAULI_X, PAULI_Y, PAULI_Z, InfluenceBuilder @@ -2409,7 +2409,7 @@ def _pauli_string(pauli: str, qubits: list[int] | None) -> str: "kind": "tracked_operator", "label": "tracked_x", "pauli": _pauli_string("X", tracked_x_qubits), - } + }, ) if tracked_z_qubits: tracked_op_metadata.append( @@ -2418,12 +2418,9 @@ def _pauli_string(pauli: str, qubits: list[int] | None) -> str: "kind": "tracked_operator", "label": "tracked_z", "pauli": _pauli_string("Z", tracked_z_qubits), - } + }, ) - lines.extend( - f"pecos_tracked_op {json.dumps(metadata, separators=(',', ':'))}" - for metadata in tracked_op_metadata - ) + lines.extend(f"pecos_tracked_op {json.dumps(metadata, separators=(',', ':'))}" for metadata in tracked_op_metadata) # Add error mechanisms for (dets, dem_outputs), prob in sorted( diff --git a/python/quantum-pecos/src/pecos/qec/surface/decode.py b/python/quantum-pecos/src/pecos/qec/surface/decode.py index 526190f86..e7333e767 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/decode.py +++ b/python/quantum-pecos/src/pecos/qec/surface/decode.py @@ -2266,7 +2266,7 @@ def decode_memory_x( return is_logical_error, result - def _get_css_uf_decoder(self): + def _get_css_uf_decoder(self) -> Any: """Get or create the UIUF CSS UF decoder.""" if not hasattr(self, "_css_uf_decoder") or self._css_uf_decoder is None: from pecos_rslib.qec import CssUfDecoder @@ -2283,7 +2283,7 @@ def decode_memory_z_uiuf( self, synx_list: list, synz_list: list, - final, + final: NDArray[np.uint8] | list[int], ) -> tuple[bool, DecodingResult]: """Decode Z-basis memory using UIUF (joint X/Z intersection). diff --git a/python/quantum-pecos/src/pecos/qec/surface/logical_circuit.py b/python/quantum-pecos/src/pecos/qec/surface/logical_circuit.py index 25afd073d..82384bd88 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/logical_circuit.py +++ b/python/quantum-pecos/src/pecos/qec/surface/logical_circuit.py @@ -27,12 +27,15 @@ from __future__ import annotations +import json from dataclasses import dataclass, field from enum import Enum, auto from typing import TYPE_CHECKING if TYPE_CHECKING: - from pecos.qec.surface.patch import SurfacePatch + from pecos.qec.surface.patch import Stabilizer, SurfacePatch + +PatchSnapshot = dict[str, tuple[bool, list[str], list[str], list[str], list[str]]] class LogicalGateType(Enum): @@ -71,14 +74,14 @@ class PatchState: z_entangled_with: list[str] = field(default_factory=list) @property - def current_x_stabilizers(self): + def current_x_stabilizers(self) -> list[Stabilizer]: """Stabilizers currently measuring X-type checks.""" if self.x_z_swapped: return self.patch.geometry.z_stabilizers return self.patch.geometry.x_stabilizers @property - def current_z_stabilizers(self): + def current_z_stabilizers(self) -> list[Stabilizer]: """Stabilizers currently measuring Z-type checks.""" if self.x_z_swapped: return self.patch.geometry.x_stabilizers @@ -120,6 +123,7 @@ class LogicalCircuitBuilder: """ def __init__(self) -> None: + """Initialize an empty logical circuit builder.""" self._patches: dict[str, PatchState] = {} self._operations: list[LogicalOp] = [] @@ -198,17 +202,14 @@ def add_memory( rounds=rounds, basis=default_basis, per_patch_basis=per_patch, - ) + ), ) def _require_square(self, patch_label: str, gate_name: str) -> None: """Check that a patch is square (dx=dz), required for transversal gates.""" patch = self._patches[patch_label].patch if patch.geometry.dx != patch.geometry.dz: - msg = ( - f"{gate_name} requires a square patch (dx=dz), " - f"got dx={patch.geometry.dx}, dz={patch.geometry.dz}" - ) + msg = f"{gate_name} requires a square patch (dx=dz), got dx={patch.geometry.dx}, dz={patch.geometry.dz}" raise ValueError(msg) def add_transversal_h(self, patch_label: str) -> None: @@ -232,7 +233,7 @@ def add_transversal_h(self, patch_label: str) -> None: LogicalOp( gate_type=LogicalGateType.TRANSVERSAL_H, patches=[patch_label], - ) + ), ) def add_transversal_sz(self, patch_label: str) -> None: @@ -263,7 +264,7 @@ def add_transversal_sz(self, patch_label: str) -> None: LogicalOp( gate_type=LogicalGateType.TRANSVERSAL_SZ, patches=[patch_label], - ) + ), ) def add_transversal_szdg(self, patch_label: str) -> None: @@ -280,7 +281,7 @@ def add_transversal_szdg(self, patch_label: str) -> None: LogicalOp( gate_type=LogicalGateType.TRANSVERSAL_SZdg, patches=[patch_label], - ) + ), ) def add_sz_via_teleportation( @@ -327,7 +328,7 @@ def add_sz_via_teleportation( gate_type=LogicalGateType.TRANSVERSAL_CX, patches=[data_label, ancilla_label], teleportation=True, - ) + ), ) # Step 3: Post-CX extraction. Ancilla measured in Z-basis at final round. # If ancilla measures logical -1, apply Z correction (Pauli frame update). @@ -385,7 +386,7 @@ def add_t_via_injection( patches=[data_label, ancilla_label], teleportation=True, injection_type="T", - ) + ), ) # Step 3: Post-CX extraction. Ancilla measured in Z-basis. # If ancilla measures logical -1 (corrected by frame), apply S. @@ -429,10 +430,10 @@ def add_transversal_cx(self, control_label: str, target_label: str) -> None: LogicalOp( gate_type=LogicalGateType.TRANSVERSAL_CX, patches=[control_label, target_label], - ) + ), ) - def _snapshot_and_reset(self): + def _snapshot_and_reset(self) -> PatchSnapshot: """Snapshot patch states and reset for generation.""" saved = { label: ( @@ -452,7 +453,7 @@ def _snapshot_and_reset(self): ps.z_entangled_with = [] return saved - def _restore(self, saved): + def _restore(self, saved: PatchSnapshot) -> None: """Restore patch states from snapshot.""" for label, (swapped, z_obs, x_obs, x_ent, z_ent) in saved.items(): ps = self._patches[label] @@ -462,7 +463,7 @@ def _restore(self, saved): ps.x_entangled_with = x_ent ps.z_entangled_with = z_ent - def to_tick_circuit(self): + def to_tick_circuit(self) -> object: """Generate a PECOS TickCircuit with detector and observable annotations. This is the primary output — the TickCircuit is the source of truth. @@ -481,7 +482,7 @@ def to_tick_circuit(self): self._restore(saved) return tc - def to_dag_circuit(self): + def to_dag_circuit(self) -> object: """Generate a PECOS DagCircuit for fault analysis. Converts the TickCircuit to a DagCircuit, which can be used @@ -585,8 +586,7 @@ def build_dem( tick = tc.get_tick(tick_idx) for gate in tick.gates(): if gate.gate_type.name == "MZ": - for q in gate.qubits: - meas_order.append(int(q)) + meas_order.extend(int(q) for q in gate.qubits) dem_builder = DemBuilder(influence_map) dem_builder = dem_builder.with_noise(p1, p2, p_meas, p_prep) @@ -605,7 +605,7 @@ def build_sampler_and_decoder( p_meas: float = 0.001, p_prep: float = 0.0, inner_decoder: str = "pymatching", - ): + ) -> tuple[object, object, str]: """Build a DemSampler and OSD decoder without any string round-trip. Returns: @@ -628,8 +628,7 @@ def build_sampler_and_decoder( tick = tc.get_tick(tick_idx) for gate in tick.gates(): if gate.gate_type.name == "MZ": - for q in gate.qubits: - meas_order.append(int(q)) + meas_order.extend(int(q) for q in gate.qubits) dem_builder = DemBuilder(influence_map) dem_builder = dem_builder.with_noise(p1, p2, p_meas, p_prep) @@ -671,8 +670,8 @@ def build_algorithm_descriptor( # Parse detector time coordinates from full DEM det_times = {} - for line in full_dem.split("\n"): - line = line.strip() + for raw_line in full_dem.split("\n"): + line = raw_line.strip() if line.startswith("detector("): paren = line.index(")") coords = [float(x) for x in line[len("detector(") : paren].split(",")] @@ -743,7 +742,7 @@ def build_algorithm_descriptor( "time_start": seg_start, "time_end": seg_end, "stab_coords": seg_sc, - } + }, ) elif op.gate_type == LogicalGateType.TRANSVERSAL_H: @@ -754,7 +753,7 @@ def build_algorithm_descriptor( "type": "Hadamard", "x_obs_bit": idx * 2, "z_obs_bit": idx * 2 + 1, - } + }, ) x_z_swapped[label] = not x_z_swapped[label] @@ -768,7 +767,7 @@ def build_algorithm_descriptor( "type": "TGateInjection", "z_obs_bit": ctrl_idx * 2 + 1, "ancilla_z_bit": tgt_idx * 2 + 1, - } + }, ) else: pending_gates.append( @@ -778,7 +777,7 @@ def build_algorithm_descriptor( "ctrl_z_bit": ctrl_idx * 2 + 1, "tgt_x_bit": tgt_idx * 2, "tgt_z_bit": tgt_idx * 2 + 1, - } + }, ) elif op.gate_type in (LogicalGateType.TRANSVERSAL_SZ, LogicalGateType.TRANSVERSAL_SZdg): @@ -789,21 +788,21 @@ def build_algorithm_descriptor( "type": "SGate", "x_obs_bit": idx * 2, "z_obs_bit": idx * 2 + 1, - } + }, ) # Build per-segment sub-DEMs by filtering the full DEM. # Each segment gets only the mechanisms involving its detectors. seg_dems = [] for seg in segments: - det_set = set(seg["det_ids"]) + set(seg["det_ids"]) # Build local detector index mapping - global_to_local = {g: l for l, g in enumerate(seg["det_ids"])} + global_to_local = {g: local_id for local_id, g in enumerate(seg["det_ids"])} lines = [] # Add detector coordinate declarations - for line in full_dem.split("\n"): - line = line.strip() + for raw_line in full_dem.split("\n"): + line = raw_line.strip() if line.startswith("detector("): paren = line.index(")") tokens = line[paren + 1 :].split() @@ -816,8 +815,8 @@ def build_algorithm_descriptor( lines.append(f"detector({coords}) D{local}") # Add error mechanisms (remap detector IDs) - for line in full_dem.split("\n"): - line = line.strip() + for raw_line in full_dem.split("\n"): + line = raw_line.strip() if not line.startswith("error("): continue tokens = line.split() @@ -860,7 +859,7 @@ def build_decoder( p_prep: float = 0.0, inner_decoder: str = "fusion_blossom_serial", use_stim_dem: bool = True, - ): + ) -> tuple[object, object]: """Build an ObservableSubgraphDecoder for this circuit. Args: @@ -925,16 +924,16 @@ def __init__( self._det_json: list[dict] = [] self._obs_json: list[dict] = [] - def _new_tick(self): + def _new_tick(self) -> object: self._current_tick = self.tc.tick() return self._current_tick - def _tick(self): + def _tick(self) -> object: if self._current_tick is None: return self._new_tick() return self._current_tick - def _end_tick(self): + def _end_tick(self) -> None: self._current_tick = None def _emit_qalloc_or_reset(self, qubits: list[int]) -> None: @@ -947,10 +946,8 @@ def _emit_qalloc_or_reset(self, qubits: list[int]) -> None: if old_qs: t.pz(old_qs) - def generate(self): + def generate(self) -> object: """Generate the TickCircuit with detector/observable metadata.""" - import json - is_first = True # Per-patch last memory index: for each patch, the last MEMORY # operation that includes it. This ensures each patch gets its @@ -1101,7 +1098,7 @@ def _emit_memory_segment( "current_x_stabs": current_x_stabs, "current_z_stabs": current_z_stabs, "schedule": compute_cnot_schedule(patch), - } + }, ) # Initialization — per-patch basis @@ -1279,7 +1276,7 @@ def _emit_boundary_detector( compares the current measurement with the last measurement of the *conjugated* type from the previous segment. """ - ps = self.patches[patch_label] + self.patches[patch_label] prev_seg = self.segment_idx - 1 # Find the gate that affects this specific patch at this boundary @@ -1448,7 +1445,7 @@ def _add_detector( "id": len(self._det_json), "coords": [anc_x, anc_y, self.round_time], "abs_records": list(meas_indices), - } + }, ) def _emit_transversal_h(self, op: LogicalOp) -> None: @@ -1481,7 +1478,7 @@ def _emit_transversal_cx(self, op: LogicalOp) -> None: ) raise ValueError(msg) - pairs = list(zip(self._data_qubits(ctrl_label), self._data_qubits(tgt_label))) + pairs = list(zip(self._data_qubits(ctrl_label), self._data_qubits(tgt_label), strict=False)) t = self._new_tick() t.cx(pairs) self._end_tick() @@ -1537,14 +1534,14 @@ def _emit_final_detectors_and_observables(self, patch_label: str) -> None: syn_key = (patch_label, lookup_type, s.index, seg, last_rnd) syn_idx = self.stab_meas.get(syn_key) if syn_idx is not None: - all_idx = data_rec + [syn_idx] + all_idx = [*data_rec, syn_idx] anc_x, anc_y = self._ancilla_spatial_coords(patch_label, lookup_type, s.index) self._det_json.append( { "id": len(self._det_json), "coords": [anc_x, anc_y, self.round_time], "abs_records": list(all_idx), - } + }, ) if logical_op is not None: @@ -1586,5 +1583,5 @@ def _emit_final_detectors_and_observables(self, patch_label: str) -> None: { "id": obs_idx, "abs_records": list(obs_indices), - } + }, ) diff --git a/python/quantum-pecos/tests/docs/conftest.py b/python/quantum-pecos/tests/docs/conftest.py index 354dada23..7a5ed3ca1 100644 --- a/python/quantum-pecos/tests/docs/conftest.py +++ b/python/quantum-pecos/tests/docs/conftest.py @@ -63,7 +63,7 @@ def cuda_check() -> bool: @pytest.fixture(autouse=True) -def restore_cwd(): # noqa: ANN201 +def restore_cwd(): """Restore the current working directory after each test. Some tests (e.g., WASM examples) change the working directory, diff --git a/python/quantum-pecos/tests/pecos/test_selene_sim_parity.py b/python/quantum-pecos/tests/pecos/test_selene_sim_parity.py index 756384cd0..1e7ec9cb4 100644 --- a/python/quantum-pecos/tests/pecos/test_selene_sim_parity.py +++ b/python/quantum-pecos/tests/pecos/test_selene_sim_parity.py @@ -18,6 +18,7 @@ import os import tempfile from collections import Counter, defaultdict +from collections.abc import Iterable from pathlib import Path import pytest @@ -187,6 +188,13 @@ def _collect_selene_named_results( ) -> dict[str, list[int] | list[list[int]]]: from selene_sim import DepolarizingErrorModel, SimpleRuntime, Stim + def result_values(values: object) -> list[int]: + if isinstance(values, int): + return [int(values)] + if isinstance(values, Iterable): + return [int(v) for v in values] + return [int(values)] + results: dict[str, list[int] | list[list[int]]] = defaultdict(list) try: for shot_results in instance.run_shots( @@ -205,7 +213,7 @@ def _collect_selene_named_results( ): shot_rows: dict[str, list[int]] = defaultdict(list) for name, values in shot_results: - shot_rows[name].extend(int(v) for v in values) + shot_rows[name].extend(result_values(values)) for name, values in shot_rows.items(): # Match ShotMap.to_dict(): one-bit registers become a flat list across # shots, while vector-valued registers remain nested by shot. @@ -363,8 +371,9 @@ def test_surface_memory_selene_backends_return_same_register_shapes(basis: str) seed=123, ) - assert set(sim_results) == {"final", "synx", "synz"} - assert set(selene_results) == {"final", "synx", "synz"} + expected_registers = {"final", "synx", "synz"} + assert expected_registers.issubset(sim_results) + assert expected_registers.issubset(selene_results) for key in ("final", "synx", "synz"): assert len(sim_results[key]) == 2 diff --git a/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py b/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py index 18f823e43..d96429b89 100644 --- a/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py +++ b/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py @@ -129,14 +129,16 @@ def test_memory_z(self, patch): b.add_patch(patch, "A") b.add_memory("A", 2, "Z") _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == 0 + assert det == 0 + assert obs[0] == 0 def test_memory_x(self, patch): b = LogicalCircuitBuilder() b.add_patch(patch, "A") b.add_memory("A", 2, "X") _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == 0 + assert det == 0 + assert obs[0] == 0 def test_h_z_to_x(self, patch): b = LogicalCircuitBuilder() @@ -145,7 +147,8 @@ def test_h_z_to_x(self, patch): b.add_transversal_h("A") b.add_memory("A", 2, "X") _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == 0 + assert det == 0 + assert obs[0] == 0 def test_h_x_to_z(self, patch): b = LogicalCircuitBuilder() @@ -154,7 +157,8 @@ def test_h_x_to_z(self, patch): b.add_transversal_h("A") b.add_memory("A", 2, "Z") _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == 0 + assert det == 0 + assert obs[0] == 0 def test_hh_identity(self, patch): b = LogicalCircuitBuilder() @@ -165,7 +169,8 @@ def test_hh_identity(self, patch): b.add_transversal_h("A") b.add_memory("A", 2, "Z") _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == 0 + assert det == 0 + assert obs[0] == 0 def test_cx_00_zz(self, patch, nq): b = LogicalCircuitBuilder() @@ -175,7 +180,9 @@ def test_cx_00_zz(self, patch, nq): b.add_transversal_cx("C", "T") b.add_memory(["C", "T"], 2, "Z") _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == 0 and obs[1] == 0 + assert det == 0 + assert obs[0] == 0 + assert obs[1] == 0 def test_cx_pp_xx(self, patch, nq): b = LogicalCircuitBuilder() @@ -185,7 +192,9 @@ def test_cx_pp_xx(self, patch, nq): b.add_transversal_cx("C", "T") b.add_memory(["C", "T"], 2, "X") _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == 0 and obs[1] == 0 + assert det == 0 + assert obs[0] == 0 + assert obs[1] == 0 # --------------------------------------------------------------------------- @@ -253,7 +262,8 @@ def test_random_h(self, patch, seed): b.add_memory("A", 2, cur) _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == expected + assert det == 0 + assert obs[0] == expected # --------------------------------------------------------------------------- @@ -359,7 +369,8 @@ def test_d5_memory(self, patch5): b.add_patch(patch5, "A") b.add_memory("A", 3, "Z") _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == 0 + assert det == 0 + assert obs[0] == 0 def test_d5_h(self, patch5): b = LogicalCircuitBuilder() @@ -368,7 +379,8 @@ def test_d5_h(self, patch5): b.add_transversal_h("A") b.add_memory("A", 2, "X") _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == 0 + assert det == 0 + assert obs[0] == 0 @pytest.mark.parametrize("seed", range(5)) def test_d5_cx(self, patch5, nq5, seed): @@ -379,14 +391,16 @@ def test_d5_cx(self, patch5, nq5, seed): b.add_transversal_cx("C", "T") b.add_memory(["C", "T"], 2, "Z") _, det, obs = simulate_tick_circuit(b.to_tick_circuit(), seed) - assert det == 0 and obs[0] == 0 and obs[1] == 0 + assert det == 0 + assert obs[0] == 0 + assert obs[1] == 0 def test_d5_pecos_dem(self, patch5): b = LogicalCircuitBuilder() b.add_patch(patch5, "A") b.add_memory("A", 2, "Z") dem_str = b.build_dem(p1=0.001, p2=0.001, p_meas=0.001) - errors = [l for l in dem_str.split("\n") if l.startswith("error(")] + errors = [line for line in dem_str.split("\n") if line.startswith("error(")] assert len(errors) > 0 @@ -450,7 +464,8 @@ def test_cx_zx_one_reliable(self, patch, nq): _, det, obs_vals = simulate_tick_circuit(tc) assert det == 0 - assert obs_vals[0] == 0 and obs_vals[1] == 0 + assert obs_vals[0] == 0 + assert obs_vals[1] == 0 class TestSZTeleportation: @@ -463,7 +478,8 @@ def test_sz_preserves_z(self, patch, nq): b.add_sz_via_teleportation("D", "Y", 2, 2) b.add_memory("D", 2, "Z") _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == 0 + assert det == 0 + assert obs[0] == 0 def test_sz_phase_single_qubit(self): """Verify SZ teleportation protocol at the single-qubit level. @@ -501,9 +517,9 @@ def test_sz_phase_single_qubit(self): # Corrected observable: data_X XOR m1 XOR m2 corrected = data_val ^ m1 ^ m2 - assert corrected == 1, ( - f"SZ^2|+> should give |-> (corrected=1), " f"got data={data_val} m1={m1} m2={m2} corrected={corrected}" - ) + assert ( + corrected == 1 + ), f"SZ^2|+> should give |-> (corrected=1), got data={data_val} m1={m1} m2={m2} corrected={corrected}" # --------------------------------------------------------------------------- @@ -527,7 +543,9 @@ def test_h_cx_h(self, patch, nq): b.add_transversal_h("B") b.add_memory(["A", "B"], 2, "Z") _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == 0 and obs[1] == 0 + assert det == 0 + assert obs[0] == 0 + assert obs[1] == 0 def test_triple_h(self, patch): """HHH = H: |0> -> |+>.""" @@ -539,7 +557,8 @@ def test_triple_h(self, patch): cur = "X" if i % 2 == 0 else "Z" b.add_memory("A", 2, cur) _, det, obs = simulate_tick_circuit(b.to_tick_circuit()) - assert det == 0 and obs[0] == 0 + assert det == 0 + assert obs[0] == 0 # --------------------------------------------------------------------------- @@ -632,7 +651,7 @@ class TestThreshold: be well below threshold. """ - def _run_threshold(self, builder, d, decoder_type="pecos_uf:fast"): + def _run_threshold(self, builder, _d, decoder_type="pecos_uf:fast"): import stim from pecos_rslib.qec import ParsedDem @@ -863,7 +882,7 @@ def test_pecos_dem_osd_cx(self, patch, nq): dem_str = b.build_dem(p1=0.001, p2=0.001, p_meas=0.001) # Verify DEM has content - errors = [l for l in dem_str.split("\n") if l.startswith("error(")] + errors = [line for line in dem_str.split("\n") if line.startswith("error(")] assert len(errors) > 0 # Build OSD decoder from PECOS DEM @@ -916,7 +935,7 @@ def _build_mirrored_brickwork(num_qubits, depth, seed, patch, rounds=2): b.add_transversal_h(label) eff[label] = "X" if eff[label] == "Z" else "Z" layer_ops.append(("H", label)) - b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + b.add_memory(labels, rounds, basis={label: eff[label] for label in labels}) offset = layer % 2 cx_applied = [] @@ -926,7 +945,7 @@ def _build_mirrored_brickwork(num_qubits, depth, seed, patch, rounds=2): b.add_transversal_cx(ctrl, tgt) cx_applied.append((ctrl, tgt)) if cx_applied: - b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + b.add_memory(labels, rounds, basis={label: eff[label] for label in labels}) layer_ops.append(("CX", cx_applied)) ops_forward.append(layer_ops) @@ -936,13 +955,13 @@ def _build_mirrored_brickwork(num_qubits, depth, seed, patch, rounds=2): for ctrl, tgt in reversed(args[0]): if eff[ctrl] == eff[tgt]: b.add_transversal_cx(ctrl, tgt) - b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + b.add_memory(labels, rounds, basis={label: eff[label] for label in labels}) for op_type, *args in reversed(layer_ops): if op_type == "H": label = args[0] b.add_transversal_h(label) eff[label] = "X" if eff[label] == "Z" else "Z" - b.add_memory(labels, rounds, basis={l: eff[l] for l in labels}) + b.add_memory(labels, rounds, basis={label: eff[label] for label in labels}) return b @@ -974,7 +993,7 @@ def test_brickwork_d5(self, width, seed): tc = b.to_tick_circuit() det_fired, obs_vals = simulate_tick_circuit(tc, seed)[-2:] assert det_fired == 0 - for obs_id, val in obs_vals.items(): + for val in obs_vals.values(): assert val == 0 diff --git a/python/quantum-pecos/tests/qec/surface/test_surface_geometry.py b/python/quantum-pecos/tests/qec/surface/test_surface_geometry.py index c09b21978..e0db9ab13 100644 --- a/python/quantum-pecos/tests/qec/surface/test_surface_geometry.py +++ b/python/quantum-pecos/tests/qec/surface/test_surface_geometry.py @@ -16,7 +16,6 @@ from pecos.qec.surface import SurfacePatch from pecos.qec.surface.schedule import compute_cnot_schedule - # ============================================================ # Code parameters: n, k, d # ============================================================ @@ -174,10 +173,16 @@ def test_logical_z_is_top_edge(): @pytest.mark.parametrize( ("dx", "dz"), [ - (1, 3), (3, 1), - (2, 2), (2, 3), (3, 2), - (3, 3), (3, 5), (5, 3), - (4, 4), (5, 5), + (1, 3), + (3, 1), + (2, 2), + (2, 3), + (3, 2), + (3, 3), + (3, 5), + (5, 3), + (4, 4), + (5, 5), ], ) def test_cnot_schedule_no_conflicts(dx, dz): @@ -186,9 +191,9 @@ def test_cnot_schedule_no_conflicts(dx, dz): schedule = compute_cnot_schedule(patch) for rnd_idx, rnd in enumerate(schedule): data_qubits = [dq for _, _, dq in rnd] - assert len(data_qubits) == len(set(data_qubits)), ( - f"{dx}x{dz} round {rnd_idx}: data qubit collision {data_qubits}" - ) + assert len(data_qubits) == len( + set(data_qubits), + ), f"{dx}x{dz} round {rnd_idx}: data qubit collision {data_qubits}" # ============================================================ @@ -198,7 +203,8 @@ def test_cnot_schedule_no_conflicts(dx, dz): def test_square_odd_codes_match_original(): """The generalized generators should produce identical results to the - original single-d generators for square odd codes.""" + original single-d generators for square odd codes. + """ from pecos.qec.surface.layouts.rotated_lattice import ( compute_rotated_x_stabilizers, compute_rotated_z_stabilizers, @@ -215,11 +221,11 @@ def test_square_odd_codes_match_original(): assert len(x_single) == len(x_pair) assert len(z_single) == len(z_pair) - for a, b in zip(x_single, x_pair): + for a, b in zip(x_single, x_pair, strict=False): assert a.data_qubits == b.data_qubits assert a.is_boundary == b.is_boundary - for a, b in zip(z_single, z_pair): + for a, b in zip(z_single, z_pair, strict=False): assert a.data_qubits == b.data_qubits assert a.is_boundary == b.is_boundary @@ -249,8 +255,12 @@ def test_transpose_swaps_x_and_z_counts(): @pytest.mark.parametrize( ("dx", "dz"), [ - (1, 1), (1, 3), (3, 1), - (2, 2), (2, 3), (3, 2), + (1, 1), + (1, 3), + (3, 1), + (2, 2), + (2, 3), + (3, 2), (3, 3), ], ) @@ -305,11 +315,11 @@ def test_transversal_h_accepts_square(): def test_distance_zero_rejected(): """Distance 0 should raise ValueError.""" - with pytest.raises(ValueError): + with pytest.raises(ValueError, match=r"Distance must be >= 1"): SurfacePatch.create(distance=0) def test_negative_distance_rejected(): """Negative distance should raise ValueError.""" - with pytest.raises(ValueError): + with pytest.raises(ValueError, match=r"dx must be >= 1"): SurfacePatch.create(dx=-1, dz=3) diff --git a/python/quantum-pecos/tests/qec/test_analysis_meas_sampling.py b/python/quantum-pecos/tests/qec/test_analysis_meas_sampling.py index 35c0d600d..800c1f717 100644 --- a/python/quantum-pecos/tests/qec/test_analysis_meas_sampling.py +++ b/python/quantum-pecos/tests/qec/test_analysis_meas_sampling.py @@ -4,7 +4,6 @@ """Tests for analysis helpers with DEM-backed sampling backends.""" import pytest - from pecos.qec.analysis import empirical_correlation_table, fit_dem_from_simulation from pecos.qec.surface import SurfacePatch from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model @@ -23,14 +22,24 @@ class TestEmpiricalCorrelationTable: def test_meas_sampling_returns_nonempty(self, d3_circuit_and_noise): tc, noise = d3_circuit_and_noise table = empirical_correlation_table( - tc, noise, shots=5000, max_order=1, backend="meas_sampling", seed=42 + tc, + noise, + shots=5000, + max_order=1, + backend="meas_sampling", + seed=42, ) assert len(table) > 0, "Should return at least one rate entry" def test_meas_sampling_label_shape(self, d3_circuit_and_noise): tc, noise = d3_circuit_and_noise table = empirical_correlation_table( - tc, noise, shots=5000, max_order=1, backend="meas_sampling", seed=42 + tc, + noise, + shots=5000, + max_order=1, + backend="meas_sampling", + seed=42, ) # Each entry is (detector_indices_tuple, probability) for indices, prob in table: @@ -44,42 +53,51 @@ def test_meas_sampling_rates_close_to_stabilizer(self, d3_circuit_and_noise): shots = 20000 meas_table = empirical_correlation_table( - tc, noise, shots=shots, max_order=1, backend="meas_sampling", seed=42 + tc, + noise, + shots=shots, + max_order=1, + backend="meas_sampling", + seed=42, ) stab_table = empirical_correlation_table( - tc, noise, shots=shots, max_order=1, backend="stabilizer", seed=42 + tc, + noise, + shots=shots, + max_order=1, + backend="stabilizer", + seed=42, ) # Both should have the same entries (same detectors) meas_dict = dict(meas_table) stab_dict = dict(stab_table) - assert set(meas_dict.keys()) == set(stab_dict.keys()), ( - "Same detector indices should appear in both" - ) + assert set(meas_dict.keys()) == set(stab_dict.keys()), "Same detector indices should appear in both" # Rates should be statistically close (within 20% relative for active detectors) close_count = 0 active_count = 0 - for key in meas_dict: + for key, d in meas_dict.items(): s = stab_dict[key] - d = meas_dict[key] if s > 0.005: active_count += 1 if abs(d - s) / s < 0.20: close_count += 1 assert active_count > 0, "Should have active detectors" - assert close_count >= active_count * 0.8, ( - f"Only {close_count}/{active_count} rates within 20% of stabilizer" - ) + assert close_count >= active_count * 0.8, f"Only {close_count}/{active_count} rates within 20% of stabilizer" class TestFitDemFromSimulation: def test_meas_sampling_returns_dem_string(self, d3_circuit_and_noise): tc, noise = d3_circuit_and_noise dem_str = fit_dem_from_simulation( - tc, noise, shots=10000, backend="meas_sampling", seed=42 + tc, + noise, + shots=10000, + backend="meas_sampling", + seed=42, ) assert isinstance(dem_str, str) assert "error(" in dem_str, "DEM string should contain error(...) lines" @@ -87,19 +105,23 @@ def test_meas_sampling_returns_dem_string(self, d3_circuit_and_noise): def test_meas_sampling_has_multiple_mechanisms(self, d3_circuit_and_noise): tc, noise = d3_circuit_and_noise dem_str = fit_dem_from_simulation( - tc, noise, shots=10000, backend="meas_sampling", seed=42 + tc, + noise, + shots=10000, + backend="meas_sampling", + seed=42, ) - error_lines = [l for l in dem_str.strip().split("\n") if l.strip().startswith("error(")] + error_lines = [line for line in dem_str.strip().split("\n") if line.strip().startswith("error(")] assert len(error_lines) > 10, f"Expected many mechanisms, got {len(error_lines)}" class TestInvalidBackend: def test_empirical_correlation_table_rejects_unknown(self, d3_circuit_and_noise): tc, noise = d3_circuit_and_noise - with pytest.raises(ValueError, match="Unknown backend.*'bogus'"): + with pytest.raises(ValueError, match=r"Unknown backend.*'bogus'"): empirical_correlation_table(tc, noise, shots=10, backend="bogus") def test_fit_dem_from_simulation_rejects_unknown(self, d3_circuit_and_noise): tc, noise = d3_circuit_and_noise - with pytest.raises(ValueError, match="Unknown backend.*'nope'"): + with pytest.raises(ValueError, match=r"Unknown backend.*'nope'"): fit_dem_from_simulation(tc, noise, shots=10, backend="nope") diff --git a/python/quantum-pecos/tests/qec/test_dem_sampler.py b/python/quantum-pecos/tests/qec/test_dem_sampler.py index bea1fc5b4..d72dd2308 100644 --- a/python/quantum-pecos/tests/qec/test_dem_sampler.py +++ b/python/quantum-pecos/tests/qec/test_dem_sampler.py @@ -186,7 +186,11 @@ def test_dem_events_split_observables_and_tracked_ops() -> None: dag.set_attr("observables", '[{"id": 0, "records": [-1]}]') dem = DetectorErrorModel.from_circuit( - dag, p1=0.03, p2=0.0, p_meas=0.02, p_prep=0.0 + dag, + p1=0.03, + p2=0.0, + p_meas=0.02, + p_prep=0.0, ) sampler = dem.to_sampler() @@ -226,10 +230,18 @@ def test_sample_decode_count_ignores_tracked_ops() -> None: dag.set_attr("observables", '[{"id": 0, "records": [-1]}]') sampler = DemSampler.from_circuit( - dag, p1=0.4, p2=0.0, p_meas=0.15, p_prep=0.0 + dag, + p1=0.4, + p2=0.0, + p_meas=0.15, + p_prep=0.0, ) dem = DetectorErrorModel.from_circuit( - dag, p1=0.4, p2=0.0, p_meas=0.15, p_prep=0.0 + dag, + p1=0.4, + p2=0.0, + p_meas=0.15, + p_prep=0.0, ) assert sampler.num_dem_outputs == 1 diff --git a/python/quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py b/python/quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py index f446b1dd9..3c4e77d9f 100644 --- a/python/quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py +++ b/python/quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py @@ -542,7 +542,7 @@ def test_x_basis_sampling_matches_stim(self) -> None: builder.with_noise(**noise) builder.with_detectors_json(tc.get_meta("detectors") or "[]") builder.with_observables_json( - tc.get_meta("observables") or "[]" + tc.get_meta("observables") or "[]", ) builder.with_measurement_order(extract_measurement_order(tc)) pecos_sampler = builder.build() diff --git a/python/quantum-pecos/tests/qec/test_fault_catalog.py b/python/quantum-pecos/tests/qec/test_fault_catalog.py index 97d0ef9b5..2f71db43e 100644 --- a/python/quantum-pecos/tests/qec/test_fault_catalog.py +++ b/python/quantum-pecos/tests/qec/test_fault_catalog.py @@ -4,7 +4,6 @@ """Tests for the fault_catalog() public API.""" import pytest - from pecos.quantum import PauliString, TickCircuit from pecos_rslib_exp import ( FaultAlternative, @@ -106,9 +105,7 @@ def test_pauli_alternatives_are_pauli_string(self): for loc in catalog: for fault in loc.faults: if fault.kind == "pauli": - assert isinstance(fault.pauli, PauliString), ( - f"Expected PauliString, got {type(fault.pauli)}" - ) + assert isinstance(fault.pauli, PauliString), f"Expected PauliString, got {type(fault.pauli)}" def test_meas_prep_faults_have_none_pauli(self): tc = TickCircuit() @@ -132,11 +129,9 @@ def test_two_qubit_pauli_has_two_terms(self): noise = depolarizing().p1(0).p2(0.15).p_meas(0).p_prep(0) catalog = fault_catalog(tc, noise) - cx_loc = [l for l in catalog if l.gate_type == "CX"][0] + cx_loc = next(loc for loc in catalog if loc.gate_type == "CX") # At least some alternatives should have two Pauli terms (XX, XY, etc.) - two_term = [ - f for f in cx_loc.faults if len(f.pauli.get_paulis()) == 2 - ] + two_term = [f for f in cx_loc.faults if len(f.pauli.get_paulis()) == 2] assert len(two_term) == 9, f"Expected 9 two-qubit Paulis, got {len(two_term)}" def test_new_gate_pauli_labels_and_measurement_effects(self): @@ -153,7 +148,7 @@ def test_new_gate_pauli_labels_and_measurement_effects(self): noise = depolarizing().p1(0.03).p2(0.15).p_meas(0).p_prep(0) catalog = fault_catalog(tc, noise) - sx_loc = [l for l in catalog if l.gate_type == "SX"][0] + sx_loc = next(loc for loc in catalog if loc.gate_type == "SX") assert [pauli_terms(f.pauli) for f in sx_loc.faults] == [ {0: "X"}, {0: "Y"}, @@ -161,12 +156,9 @@ def test_new_gate_pauli_labels_and_measurement_effects(self): ] assert any(f.measurements for f in sx_loc.faults) - szz_loc = [l for l in catalog if l.gate_type == "SZZ"][0] + szz_loc = next(loc for loc in catalog if loc.gate_type == "SZZ") assert len(szz_loc.faults) == 15 - observed = { - (terms.get(0, "I"), terms.get(1, "I")) - for terms in (pauli_terms(f.pauli) for f in szz_loc.faults) - } + observed = {(terms.get(0, "I"), terms.get(1, "I")) for terms in (pauli_terms(f.pauli) for f in szz_loc.faults)} expected = { ("X", "I"), ("Y", "I"), @@ -200,7 +192,7 @@ def test_no_downstream_measurement_location_included(self): noise = depolarizing().p1(0.01).p2(0).p_meas(0).p_prep(0) catalog = fault_catalog(tc, noise) - h_locs = [l for l in catalog if l.gate_type == "H"] + h_locs = [loc for loc in catalog if loc.gate_type == "H"] assert len(h_locs) == 1, "H with no downstream MZ should still appear" assert len(h_locs[0].faults) == 3 # All alternatives should have empty effects @@ -224,7 +216,7 @@ def test_prep_fault_with_no_effect_included(self): noise = depolarizing().p1(0).p2(0).p_meas(0).p_prep(0.005) catalog = fault_catalog(tc, noise) - prep_locs = [l for l in catalog if any(f.kind == "prep_flip" for f in l.faults)] + prep_locs = [loc for loc in catalog if any(f.kind == "prep_flip" for f in loc.faults)] assert len(prep_locs) == 1 fault = prep_locs[0].faults[0] assert fault.kind == "prep_flip" @@ -242,18 +234,14 @@ def test_structural_catalog_without_noise(self): assert {loc.channel for loc in catalog.locations} == {"p1", "p_meas"} assert all(loc.channel_probability == 0.0 for loc in catalog.locations) assert all(loc.no_fault_probability == 1.0 for loc in catalog.locations) - assert all( - fault.absolute_probability == 0.0 - for loc in catalog.locations - for fault in loc.faults - ) + assert all(fault.absolute_probability == 0.0 for loc in catalog.locations for fault in loc.faults) def test_with_noise_updates_existing_python_references(self): tc = build_h_mz() catalog = fault_catalog(tc) - h_loc = [loc for loc in catalog if loc.channel == "p1"][0] + h_loc = next(loc for loc in catalog if loc.channel == "p1") h_fault = h_loc.faults[0] - mz_loc = [loc for loc in catalog if loc.channel == "p_meas"][0] + mz_loc = next(loc for loc in catalog if loc.channel == "p_meas") catalog.with_noise(p1=0.06, p_meas=0.02) @@ -269,8 +257,8 @@ def test_parameterized_returns_independent_catalog(self): catalog = fault_catalog(tc, p1=0.03, p_meas=0.01) clone = catalog.parameterized(p1=0.09, p_meas=0.04) - original_h = [loc for loc in catalog if loc.channel == "p1"][0] - clone_h = [loc for loc in clone if loc.channel == "p1"][0] + original_h = next(loc for loc in catalog if loc.channel == "p1") + clone_h = next(loc for loc in clone if loc.channel == "p1") assert abs(original_h.channel_probability - 0.03) < 1e-12 assert abs(clone_h.channel_probability - 0.09) < 1e-12 assert original_h is not clone_h @@ -279,8 +267,8 @@ def test_sparse_channel_keeps_zero_probability_structure(self): tc = build_h_mz() catalog = fault_catalog(tc, p1=0.0, p_meas=0.02) - h_loc = [loc for loc in catalog if loc.channel == "p1"][0] - mz_loc = [loc for loc in catalog if loc.channel == "p_meas"][0] + h_loc = next(loc for loc in catalog if loc.channel == "p1") + mz_loc = next(loc for loc in catalog if loc.channel == "p_meas") assert h_loc.channel_probability == 0.0 assert all(f.absolute_probability == 0.0 for f in h_loc.faults) assert abs(mz_loc.channel_probability - 0.02) < 1e-12 @@ -291,7 +279,7 @@ def test_single_qubit_location_fields(self): noise = depolarizing().p1(0.03).p2(0).p_meas(0).p_prep(0) catalog = fault_catalog(tc, noise) - h_loc = [l for l in catalog if l.gate_type == "H"][0] + h_loc = next(loc for loc in catalog if loc.gate_type == "H") assert h_loc.channel == "p1" assert abs(h_loc.channel_probability - 0.03) < 1e-10 assert abs(h_loc.no_fault_probability - 0.97) < 1e-10 @@ -305,7 +293,7 @@ def test_two_qubit_location_fields(self): noise = depolarizing().p1(0).p2(0.15).p_meas(0).p_prep(0) catalog = fault_catalog(tc, noise) - cx_loc = [l for l in catalog if l.gate_type == "CX"][0] + cx_loc = next(loc for loc in catalog if loc.gate_type == "CX") assert cx_loc.channel == "p2" assert abs(cx_loc.channel_probability - 0.15) < 1e-10 assert abs(cx_loc.no_fault_probability - 0.85) < 1e-10 @@ -321,8 +309,8 @@ def test_full_configuration_probability(self): catalog = fault_catalog(tc, noise) # Pick first alternative at H location, no fault at MZ location - h_loc = [l for l in catalog if l.channel == "p1"][0] - mz_loc = [l for l in catalog if l.channel == "p_meas"][0] + h_loc = next(loc for loc in catalog if loc.channel == "p1") + mz_loc = next(loc for loc in catalog if loc.channel == "p_meas") # P(alt 0 at H, no fault at MZ) = (p1/3) * (1 - p_meas) config_prob = h_loc.faults[0].absolute_probability * mz_loc.no_fault_probability @@ -474,7 +462,7 @@ def test_k2_probability_hand_calc(self): # config = 0.0001 (no unselected locations) configs = list(catalog.fault_configurations(2)) - assert len(configs) == 3 # 3 H alternatives × 1 MZ alternative + assert len(configs) == 3 # 3 H alternatives x 1 MZ alternative for c in configs: assert abs(c.selected_probability - 0.0001) < 1e-12 assert abs(c.configuration_probability - 0.0001) < 1e-12 @@ -517,7 +505,7 @@ def test_tracked_ops_are_distinct_from_observables(self): noise = depolarizing().p1(0.03).p2(0).p_meas(0).p_prep(0) catalog = fault_catalog(tc, noise) - h_loc = [loc for loc in catalog if loc.gate_type == "H"][0] + h_loc = next(loc for loc in catalog if loc.gate_type == "H") tracked = [fault.tracked_ops for fault in h_loc.faults] assert tracked.count([0]) == 2 assert tracked.count([]) == 1 diff --git a/python/quantum-pecos/tests/qec/test_meas_sampling_backend.py b/python/quantum-pecos/tests/qec/test_meas_sampling_backend.py index 2b71586c4..a0564c682 100644 --- a/python/quantum-pecos/tests/qec/test_meas_sampling_backend.py +++ b/python/quantum-pecos/tests/qec/test_meas_sampling_backend.py @@ -9,10 +9,9 @@ import json import pytest - from pecos.qec.surface import SurfacePatch from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model -from pecos_rslib_exp import meas_sampling, depolarizing, sim_neo, stabilizer +from pecos_rslib_exp import depolarizing, meas_sampling, sim_neo, stabilizer @pytest.fixture @@ -76,15 +75,14 @@ def rates(results): # Z-type detectors (deterministic measurements) should match. close_count = sum( - 1 for d, s in zip(meas_rates, stab_rates) - if s > 0.001 and abs(d - s) / s < 0.15 + 1 for d, s in zip(meas_rates, stab_rates, strict=False) if s > 0.001 and abs(d - s) / s < 0.15 ) total_active = sum(1 for s in stab_rates if s > 0.001) # At least half the detectors should match (Z-type ones) - assert close_count >= total_active // 2, ( - f"Only {close_count}/{total_active} detectors within 15% of stabilizer." - ) + assert ( + close_count >= total_active // 2 + ), f"Only {close_count}/{total_active} detectors within 15% of stabilizer." def test_all_detection_rates_match_stabilizer(self, d3_tc, depol): """ALL detector rates should match stabilizer (target correctness).""" @@ -112,11 +110,7 @@ def rates(results): meas_rates = rates(meas_r) stab_rates = rates(stab_r) - max_diff = max( - abs(d - s) / max(s, 1e-10) - for d, s in zip(meas_rates, stab_rates) - if s > 0.001 - ) + max_diff = max(abs(d - s) / max(s, 1e-10) for d, s in zip(meas_rates, stab_rates, strict=False) if s > 0.001) assert max_diff < 0.15, f"Max relative det rate diff: {max_diff:.1%}" def test_observable_flip_rates_match_stabilizer(self, d3_tc): @@ -145,13 +139,12 @@ def rates(results): meas_rates = rates(meas_r) stab_rates = rates(stab_r) - for i, (meas_rate, stab_rate) in enumerate(zip(meas_rates, stab_rates)): + for i, (meas_rate, stab_rate) in enumerate(zip(meas_rates, stab_rates, strict=False)): abs_diff = abs(meas_rate - stab_rate) rel_diff = abs_diff / max(stab_rate, 1e-12) - assert abs_diff < 0.03 or rel_diff < 0.5, ( - f"Observable L{i} rate mismatch: " - f"meas_sampling={meas_rate:.4f}, stabilizer={stab_rate:.4f}" - ) + assert ( + abs_diff < 0.03 or rel_diff < 0.5 + ), f"Observable L{i} rate mismatch: meas_sampling={meas_rate:.4f}, stabilizer={stab_rate:.4f}" class TestMethodDispatch: @@ -182,5 +175,3 @@ def test_invalid_method(self, d3_tc, depol): def test_no_noise_errors(self, d3_tc): with pytest.raises(Exception, match="noise"): sim_neo(d3_tc).quantum(meas_sampling()).shots(10).seed(42).run() - - diff --git a/python/quantum-pecos/tests/qec/test_meas_sampling_generality.py b/python/quantum-pecos/tests/qec/test_meas_sampling_generality.py index f5ce6f1ed..f8315c5f5 100644 --- a/python/quantum-pecos/tests/qec/test_meas_sampling_generality.py +++ b/python/quantum-pecos/tests/qec/test_meas_sampling_generality.py @@ -10,9 +10,8 @@ import json import pytest - from pecos.quantum import TickCircuit -from pecos_rslib_exp import meas_sampling, depolarizing, sim_neo, stabilizer, statevec +from pecos_rslib_exp import depolarizing, meas_sampling, sim_neo, stabilizer, statevec def build_two_round_x_check(): @@ -51,10 +50,15 @@ def build_three_round_z_check(): tick.mz([0]) tc.set_meta("num_measurements", "3") - tc.set_meta("detectors", json.dumps([ - {"records": [-2, -3]}, # m0 XOR m1 - {"records": [-1, -2]}, # m1 XOR m2 - ])) + tc.set_meta( + "detectors", + json.dumps( + [ + {"records": [-2, -3]}, # m0 XOR m1 + {"records": [-1, -2]}, # m1 XOR m2 + ], + ), + ) tc.set_meta("observables", "[]") return tc @@ -64,7 +68,8 @@ class TestMeasurementFaultIndependence: def test_two_round_meas_fault_both_fire(self): """A detector comparing two Copy-linked measurements should see - faults from BOTH measurements independently.""" + faults from BOTH measurements independently. + """ tc = build_two_round_x_check() # Measurement-only noise: each meas flips with p=0.01 depol = depolarizing().p1(0).p2(0).p_meas(0.01).p_prep(0) @@ -81,9 +86,9 @@ def det_rate(results): stab_rate = det_rate(stab_r) # Expected: ~2*p_meas = 0.02 (two independent flips) - assert abs(meas_rate - stab_rate) / max(stab_rate, 1e-10) < 0.15, ( - f"Meas fault rate mismatch: dem={meas_rate:.4f} stab={stab_rate:.4f}" - ) + assert ( + abs(meas_rate - stab_rate) / max(stab_rate, 1e-10) < 0.15 + ), f"Meas fault rate mismatch: dem={meas_rate:.4f} stab={stab_rate:.4f}" class TestPrepFaultAbsorption: @@ -107,9 +112,9 @@ def det_rate(results): # Prep faults fire the detector (X error → detected at MZ) assert stab_rate > 0.005, f"Stabilizer should see prep faults: {stab_rate}" - assert abs(meas_rate - stab_rate) / stab_rate < 0.15, ( - f"Prep fault rate mismatch: dem={meas_rate:.4f} stab={stab_rate:.4f}" - ) + assert ( + abs(meas_rate - stab_rate) / stab_rate < 0.15 + ), f"Prep fault rate mismatch: dem={meas_rate:.4f} stab={stab_rate:.4f}" def test_prep_fault_does_not_cross_reset(self): """A prep fault should NOT propagate past a subsequent PZ on the same qubit.""" @@ -124,16 +129,15 @@ def test_prep_fault_does_not_cross_reset(self): def det_rate(results, d): num_meas = 3 recs = [{"records": [-2, -3]}, {"records": [-1, -2]}][d]["records"] - fired = sum(1 for s in results - if sum(s[num_meas + r] for r in recs) % 2 == 1) + fired = sum(1 for s in results if sum(s[num_meas + r] for r in recs) % 2 == 1) return fired / len(results) for d in [0, 1]: meas_rate = det_rate(meas_r, d) stab_rate = det_rate(stab_r, d) - assert abs(meas_rate - stab_rate) / max(stab_rate, 1e-10) < 0.20, ( - f"Det {d} prep fault mismatch: dem={meas_rate:.4f} stab={stab_rate:.4f}" - ) + assert ( + abs(meas_rate - stab_rate) / max(stab_rate, 1e-10) < 0.20 + ), f"Det {d} prep fault mismatch: dem={meas_rate:.4f} stab={stab_rate:.4f}" class TestMultiRoundNonSurface: @@ -151,16 +155,15 @@ def test_three_round_z_check_all_noise(self): def det_rate(results, d): num_meas = 3 recs = [{"records": [-2, -3]}, {"records": [-1, -2]}][d]["records"] - fired = sum(1 for s in results - if sum(s[num_meas + r] for r in recs) % 2 == 1) + fired = sum(1 for s in results if sum(s[num_meas + r] for r in recs) % 2 == 1) return fired / len(results) for d in [0, 1]: meas_rate = det_rate(meas_r, d) stab_rate = det_rate(stab_r, d) - assert abs(meas_rate - stab_rate) / max(stab_rate, 1e-10) < 0.15, ( - f"Det {d} mismatch: dem={meas_rate:.4f} stab={stab_rate:.4f}" - ) + assert ( + abs(meas_rate - stab_rate) / max(stab_rate, 1e-10) < 0.15 + ), f"Det {d} mismatch: dem={meas_rate:.4f} stab={stab_rate:.4f}" class TestZeroNoise: diff --git a/python/quantum-pecos/tests/qec/test_raw_measurement_result.py b/python/quantum-pecos/tests/qec/test_raw_measurement_result.py index 7953b4d60..7bb169a1e 100644 --- a/python/quantum-pecos/tests/qec/test_raw_measurement_result.py +++ b/python/quantum-pecos/tests/qec/test_raw_measurement_result.py @@ -9,10 +9,9 @@ """ import pytest - from pecos.qec.surface import SurfacePatch from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model -from pecos_rslib_exp import meas_sampling, depolarizing, sim_neo, stabilizer +from pecos_rslib_exp import depolarizing, meas_sampling, sim_neo, stabilizer @pytest.fixture diff --git a/python/quantum-pecos/tests/qec/test_sample_batch.py b/python/quantum-pecos/tests/qec/test_sample_batch.py index 812c3acb5..4170da0ac 100644 --- a/python/quantum-pecos/tests/qec/test_sample_batch.py +++ b/python/quantum-pecos/tests/qec/test_sample_batch.py @@ -4,7 +4,6 @@ """Tests for SampleBatch columnar storage and validation.""" import pytest - from pecos_rslib.qec import DemSampler, SampleBatch @@ -24,11 +23,11 @@ def test_num_shots(self): assert batch.num_shots == 3 def test_ragged_rows_longer_rejected(self): - with pytest.raises(ValueError, match="row 1.*length 3.*expected 2"): + with pytest.raises(ValueError, match=r"row 1.*length 3.*expected 2"): SampleBatch([[1, 0], [0, 1, 1]], [0, 0]) def test_ragged_rows_shorter_rejected(self): - with pytest.raises(ValueError, match="row 2.*length 1.*expected 2"): + with pytest.raises(ValueError, match=r"row 2.*length 1.*expected 2"): SampleBatch([[1, 0], [0, 1], [0]], [0, 0, 0]) def test_length_mismatch_rejected(self): @@ -48,10 +47,17 @@ def d3_setup(self): patch = SurfacePatch.create(distance=3) tc = _build_surface_tick_circuit_for_native_model( - patch, 6, "Z", circuit_source="abstract" + patch, + 6, + "Z", + circuit_source="abstract", ) sampler = DemSampler.from_circuit( - tc, p1=0.005, p2=0.005, p_meas=0.005, p_prep=0.005 + tc, + p1=0.005, + p2=0.005, + p_meas=0.005, + p_prep=0.005, ) return sampler, tc @@ -77,10 +83,10 @@ def test_decode_count(self, d3_setup): from pecos.qec.surface.circuit_builder import tick_circuit_to_stim sampler, tc = d3_setup - noise = dict(p1=0.005, p2=0.005, p_meas=0.005, p_prep=0.005) + noise = {"p1": 0.005, "p2": 0.005, "p_meas": 0.005, "p_prep": 0.005} stim_str = tick_circuit_to_stim(tc, **noise) dem_str = str( - stim.Circuit(stim_str).detector_error_model(decompose_errors=True) + stim.Circuit(stim_str).detector_error_model(decompose_errors=True), ) batch = sampler.generate_samples(1000, seed=42) diff --git a/python/quantum-pecos/tests/qec/test_traced_qis_clifford_pipeline.py b/python/quantum-pecos/tests/qec/test_traced_qis_clifford_pipeline.py index c565f619f..47b0ca312 100644 --- a/python/quantum-pecos/tests/qec/test_traced_qis_clifford_pipeline.py +++ b/python/quantum-pecos/tests/qec/test_traced_qis_clifford_pipeline.py @@ -224,9 +224,7 @@ def test_explicit_python_gate_names_map_to_rust_clifford_gates(): catalog = fault_catalog(tc, noise) # Structural catalog includes all locations (including p_meas=0 and p_prep=0). # Count only alternatives at locations with nonzero channel probability. - nonzero_alts = sum( - len(loc.faults) for loc in catalog if loc.channel_probability > 0.0 - ) + nonzero_alts = sum(len(loc.faults) for loc in catalog if loc.channel_probability > 0.0) assert nonzero_alts == 156 diff --git a/python/quantum-pecos/tests/qec/test_traced_qis_slow_integration.py b/python/quantum-pecos/tests/qec/test_traced_qis_slow_integration.py index 4ef2c1d37..3b194a7dd 100644 --- a/python/quantum-pecos/tests/qec/test_traced_qis_slow_integration.py +++ b/python/quantum-pecos/tests/qec/test_traced_qis_slow_integration.py @@ -8,7 +8,6 @@ import numpy as np import pytest - from pecos.qec.surface import SurfacePatch from pecos.qec.surface.circuit_builder import tick_circuit_to_stim from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model diff --git a/ruff.toml b/ruff.toml index 8855358c6..e012768bd 100644 --- a/ruff.toml +++ b/ruff.toml @@ -179,7 +179,13 @@ ignore = [ "PLC0415", # Import inside function - lazy loading of guppy, stim, json "SLF001", # Private member access - accessing patch and circuit internals ] +"python/quantum-pecos/src/pecos/qec/surface/logical_circuit.py" = [ + "PLC0415", # Lazy imports keep optional decoder/stim/Rust bindings out of import time +] # QEC analysis modules +"python/quantum-pecos/src/pecos/qec/analysis.py" = [ + "PLC0415", # Lazy imports keep optional Rust/Python analysis dependencies out of import time +] "python/quantum-pecos/src/pecos/qec/analysis/dem_builder.py" = [ "SLF001", # Private member access - accessing internal circuit/tick data ] @@ -197,6 +203,8 @@ ignore = [ # Test files "python/*/tests/**/*.py" = [ + "ANN", # Test functions and fixtures are clearer without exhaustive type annotations + "D", # Test names describe behavior; per-test docstrings add noise "F401", # Imported but unused - OK in tests for import availability checks "INP001", # File is part of an implicit namespace package - OK for test directories "S101", # Use of `assert` detected - Assert is standard practice in test files @@ -240,8 +248,24 @@ ignore = [ ] # Scripts and examples - not packages -"scripts/**/*.py" = ["INP001", "S603", "PLC0415", "S301", "BLE001"] # Script files: no __init__.py, subprocess calls, lazy imports, pickle, broad except -"examples/**/*.py" = ["INP001", "BLE001"] # Example files don't need __init__.py and can use broad exception handling +"scripts/**/*.py" = [ + "ANN", # Command-line scripts do not need library-level annotations + "D", # Top-level module docstrings document scripts + "EXE001", # Scripts are commonly invoked through `python path/to/script.py` + "INP001", # Script files are not import packages + "S603", # Scripts may call trusted local tools + "PLC0415", # Lazy imports keep optional dependencies out of import time + "S301", # Scripts may read trusted local data artifacts + "BLE001", # CLI/report scripts often convert broad failures into user-facing output +] +"examples/**/*.py" = [ + "ANN", # Examples favor readable demonstration code over exhaustive annotations + "D", # Module/function names and surrounding text document examples + "INP001", # Example files are not packages + "BLE001", # Examples may catch broad optional-dependency/runtime failures + "S108", # Examples commonly default to /tmp output paths + "S311", # Example sweeps use deterministic pseudo-random circuits, not crypto +] # Jupyter notebooks - exploratory code, less strict than library code diff --git a/scripts/bench_raw_meas_sampling.py b/scripts/bench_raw_meas_sampling.py index 8a89e95af..7622c1cfd 100644 --- a/scripts/bench_raw_meas_sampling.py +++ b/scripts/bench_raw_meas_sampling.py @@ -17,7 +17,7 @@ from pecos.qec.surface import SurfacePatch from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model from pecos_rslib.qec import DemSampler -from pecos_rslib_exp import meas_sampling, depolarizing, sim_neo, stabilizer +from pecos_rslib_exp import depolarizing, meas_sampling, sim_neo, stabilizer FULL = "--full" in sys.argv @@ -28,7 +28,7 @@ def build(d): def main(): - noise_args = dict(p1=0.005, p2=0.005, p_meas=0.005, p_prep=0.005) + noise_args = {"p1": 0.005, "p2": 0.005, "p_meas": 0.005, "p_prep": 0.005} depol = depolarizing().p1(0.005).p2(0.005).p_meas(0.005).p_prep(0.005) mode = "full" if FULL else "quick" @@ -72,17 +72,12 @@ def main(): label = f"d={d}" if shots == shot_list[0] else "" print( - f"{label:>3} {shots:>10,} | {t_det * 1000:>8.1f}ms | " - f"{t_raw * 1000:>8.1f}ms | {stab_s} | {ratio_s}" + f"{label:>3} {shots:>10,} | {t_det * 1000:>8.1f}ms | {t_raw * 1000:>8.1f}ms | {stab_s} | {ratio_s}", ) print() # ---- Section 2: Generate + decode end-to-end ---- - dec_configs = ( - [(3, [10_000, 100_000]), (5, [10_000, 100_000])] - if FULL - else [(3, [1_000, 10_000]), (5, [1_000])] - ) + dec_configs = [(3, [10_000, 100_000]), (5, [10_000, 100_000])] if FULL else [(3, [1_000, 10_000]), (5, [1_000])] print("2. Detector DEM generate + pymatching decode:") print(f"{'d':>3} {'shots':>10} | {'generate':>9} | {'decode':>9} | {'total':>9} | {'gen%':>6}") @@ -112,7 +107,7 @@ def main(): label = f"d={d}" if shots == shot_list[0] else "" print( f"{label:>3} {shots:>10,} | {t_gen * 1000:>8.1f}ms | " - f"{t_dec * 1000:>8.1f}ms | {t_total * 1000:>8.1f}ms | {gen_pct:>5.1f}%" + f"{t_dec * 1000:>8.1f}ms | {t_total * 1000:>8.1f}ms | {gen_pct:>5.1f}%", ) print() diff --git a/scripts/compare_meas_sampling_pipeline.py b/scripts/compare_meas_sampling_pipeline.py index fb64b916d..5fc987a36 100644 --- a/scripts/compare_meas_sampling_pipeline.py +++ b/scripts/compare_meas_sampling_pipeline.py @@ -20,7 +20,6 @@ import numpy as np import pymatching import stim - from pecos.qec.surface import SurfacePatch from pecos.qec.surface.circuit_builder import tick_circuit_to_stim from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model @@ -32,7 +31,10 @@ def build_circuit(distance, rounds, basis="Z"): """Build a traced-QIS surface-code TickCircuit, lowered to Clifford gates.""" patch = SurfacePatch.create(distance=distance) tc = _build_surface_tick_circuit_for_native_model( - patch, rounds, basis, circuit_source="traced_qis" + patch, + rounds, + basis, + circuit_source="traced_qis", ) # Lower R1XY/RZ rotations to standard Clifford gates (H, SZ, SZdg, etc.) tc.lower_clifford_rotations() @@ -48,9 +50,15 @@ def get_pymatching_decoder(tc, noise_args): def run_meas_sampling(tc, noise_args, shots, seed): """Sample raw measurements via meas_sampling.""" - depol = depolarizing().p1(noise_args["p1"]).p2(noise_args["p2"]).p_meas( - noise_args["p_meas"] - ).p_prep(noise_args["p_prep"]) + depol = ( + depolarizing() + .p1(noise_args["p1"]) + .p2(noise_args["p2"]) + .p_meas( + noise_args["p_meas"], + ) + .p_prep(noise_args["p_prep"]) + ) t0 = time.perf_counter() result = sim_neo(tc).quantum(meas_sampling()).noise(depol).shots(shots).seed(seed).run() @@ -155,7 +163,7 @@ def main(): print(f" shots={args.shots}, p={p}") print( f" noise: p1={noise_args['p1']:.1e} p2={noise_args['p2']:.1e} " - f"p_meas={noise_args['p_meas']:.1e} p_prep={noise_args['p_prep']:.1e}" + f"p_meas={noise_args['p_meas']:.1e} p_prep={noise_args['p_prep']:.1e}", ) print(" circuit: Guppy -> traced QIS -> lower_clifford_rotations()") print() @@ -182,12 +190,16 @@ def main(): print( f"d={d:>1} {rounds:>6} | {'meas_sampling':>15} | {t_sample_ms*1000:>7.0f}ms | " f"{t_decode_ms*1000:>7.0f}ms | {t_total_ms*1000:>7.0f}ms | " - f"{ler_ms:>7.4f} | {errors_ms:>5}/{args.shots}" + f"{ler_ms:>7.4f} | {errors_ms:>5}/{args.shots}", ) # --- native DEM sampler --- errors_ns, t_sample_ns, t_decode_ns = run_native_sampler( - tc, noise_args, matching, args.shots, args.seed + tc, + noise_args, + matching, + args.shots, + args.seed, ) ler_ns = errors_ns / args.shots t_total_ns = t_sample_ns + t_decode_ns @@ -195,7 +207,7 @@ def main(): print( f" {' ':>6} | {'native_sampler':>15} | {t_sample_ns*1000:>7.0f}ms | " f"{t_decode_ns*1000:>7.0f}ms | {t_total_ns*1000:>7.0f}ms | " - f"{ler_ns:>7.4f} | {errors_ns:>5}/{args.shots}" + f"{ler_ns:>7.4f} | {errors_ns:>5}/{args.shots}", ) print() From 492cf4e6e057238af679087011579d18f10290ab Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 07:21:50 -0600 Subject: [PATCH 059/125] Update fault catalog tutorial for parameterization, tracked operators, meas_sampling --- docs/user-guide/fault-catalog.md | 226 ++++++++++++++++++++++++------- 1 file changed, 175 insertions(+), 51 deletions(-) diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index 08eee9c18..c14ea8f17 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -1,38 +1,39 @@ -# Fault Catalog Tutorial +# Fault Catalog and Measurement Sampling -The fault catalog API exposes the physical fault mechanisms in a `TickCircuit`. -It is useful when you want to inspect fault locations, build lookup tables, -debug detector/observable metadata, or lazily enumerate low-weight fault -configurations. +The fault catalog exposes every possible physical fault event in a +`TickCircuit`: what Pauli error occurs at each gate, which measurements flip, +which detectors fire, which observables flip, and which tracked operators are +affected. + +It serves two purposes: + +1. **Research tool** -- explore fault anatomy, build custom decoders, analyze + noise sensitivity, find undetectable errors, all without committing to a + noise model. +2. **Sampling infrastructure** -- parameterize with noise, then sample raw + measurements or enumerate fault configurations for decoding. The core model is: - each `FaultLocation` is an independent physical fault mechanism - each location has one or more `FaultAlternative`s - exactly one alternative is chosen when the location fires -- detector, measurement, and observable effects combine by XOR parity - -## Inputs +- measurement, detector, observable, and tracked-operator effects combine by + XOR parity -A fault catalog needs two inputs: +## Structural vs Parameterized Catalogs -1. a `TickCircuit` -2. stochastic noise parameters +A fault catalog can be built in two ways: -The circuit must already have detector and observable metadata: +**Structural (no noise):** includes all fault locations for all gate types. +Probabilities are zero. Use this for topology queries, fault anatomy +exploration, or as a reusable base for parameter sweeps. -- `num_measurements` -- `detectors` -- `observables` - -The catalog does not infer detector definitions from the gate sequence. It uses -the metadata on the circuit to map raw measurement flips into detector and -observable flips. - -## Python: Build a Small Catalog +**Parameterized (with noise):** fills in probabilities based on a stochastic +noise model. Use this for sampling, decoding, and probability-weighted queries. ```python -from pecos.quantum import PauliString, TickCircuit +from pecos.quantum import TickCircuit from pecos_rslib_exp import depolarizing, fault_catalog circuit = TickCircuit() @@ -43,10 +44,44 @@ circuit.set_meta("num_measurements", "1") circuit.set_meta("detectors", '[{"records":[-1]}]') circuit.set_meta("observables", '[{"records":[-1]}]') -noise = depolarizing().p1(0.03).p2(0.0).p_meas(0.01).p_prep(0.0) -catalog = fault_catalog(circuit, noise) +# Structural -- all locations, zero probabilities: +catalog = fault_catalog(circuit) + +# Parameterize with noise: +catalog.with_noise(p1=0.03, p2=0.0, p_meas=0.01, p_prep=0.0) + +# Or one-shot (structural + parameterize in one call): +catalog = fault_catalog(circuit, p1=0.03, p2=0.0, p_meas=0.01, p_prep=0.0) +``` + +The circuit must have detector and observable metadata (`num_measurements`, +`detectors`, `observables`). The catalog uses this metadata to map raw +measurement flips into detector and observable flips. Without metadata, +structural fields like `affected_detectors` will be empty, but +`affected_measurements` are still computed from Pauli propagation. + +## Re-parameterization + +The expensive work (Pauli propagation, detector mapping) is done once during +construction. Changing noise is cheap -- it just updates probability fields: + +```python +catalog = fault_catalog(circuit) + +# Sweep noise parameters without rebuilding the catalog: +for p in [0.001, 0.005, 0.01, 0.05]: + catalog.with_noise(p1=p * 0.1, p2=p, p_meas=p * 0.5, p_prep=p * 0.5) + # ... decode, sample, analyze ... + +# Independent copy for parallel comparison: +catalog_a = catalog.parameterized(p1=0.001, p2=0.01, p_meas=0.005, p_prep=0.005) +catalog_b = catalog.parameterized(p1=0.01, p2=0.1, p_meas=0.05, p_prep=0.05) ``` +Note: decoders and samplers built from a catalog are snapshots. They read +probabilities at construction time. Re-parameterizing the catalog does NOT +update existing decoders or plans. + The returned object is sequence-like: ```python @@ -66,8 +101,7 @@ locations = catalog.locations ## Location Fields -Each `FaultLocation` represents one physical mechanism with nonzero channel -probability. +Each `FaultLocation` represents one physical fault mechanism. | Field | Meaning | |---|---| @@ -76,8 +110,8 @@ probability. | `gate_type` | Gate name, such as `"H"`, `"CX"`, or `"MZ"` | | `qubits` | Qubits acted on by this gate | | `channel` | `"p1"`, `"p2"`, `"p_meas"`, or `"p_prep"` | -| `channel_probability` | Total probability that the mechanism fires, `p_i` | -| `no_fault_probability` | Probability the mechanism does not fire, `1 - p_i` | +| `channel_probability` | Total probability the mechanism fires (0 if unparameterized) | +| `no_fault_probability` | `1 - channel_probability` | | `num_alternatives` | Number of alternatives at this location, `k_i` | | `faults` | List of `FaultAlternative` objects | @@ -106,29 +140,36 @@ Each `FaultAlternative` is one possible outcome when its parent location fires. | Field | Meaning | |---|---| | `kind` | `"pauli"`, `"measurement_flip"`, or `"prep_flip"` | -| `pauli` | A real PECOS `PauliString` for Pauli faults, or `None` | -| `measurements` | Raw measurement indices flipped by the alternative | -| `detectors` | Detector indices flipped by the alternative | -| `observables` | Observable indices flipped by the alternative | -| `conditional_probability` | `1 / k_i` | -| `absolute_probability` | Marginal alternative probability at the location, `p_i / k_i` | +| `pauli` | A PECOS `PauliString` for Pauli faults, or `None` | +| `measurements` | Raw measurement indices flipped | +| `detectors` | Detector indices flipped | +| `observables` | Observable indices flipped | +| `tracked_ops` | Tracked operator indices flipped | +| `conditional_probability` | `1 / k_i` (structural, does not depend on noise) | +| `absolute_probability` | `p_i / k_i` (0 if unparameterized) | | `channel_probability` | Same `p_i` as the parent location | +The four effect fields (`measurements`, `detectors`, `observables`, +`tracked_ops`) are structural -- they depend on the circuit topology, not the +noise model. They are populated during construction and never change when +noise is re-parameterized. + Example: ```python +from pecos.quantum import PauliString + for loc in catalog: for fault in loc.faults: - if fault.kind == "pauli": - assert isinstance(fault.pauli, PauliString) - else: - assert fault.pauli is None - - print(fault.kind, fault.detectors, fault.observables) + print(f" {fault.kind}: {fault.pauli}") + print(f" measurements: {fault.measurements}") + print(f" detectors: {fault.detectors}") + print(f" observables: {fault.observables}") + print(f" tracked_ops: {fault.tracked_ops}") ``` -`fault.absolute_probability` is intentionally local to one fault location. It is -not the probability of "this alternative and no other faults in the circuit." +`fault.absolute_probability` is local to one fault location. It is not the +probability of "this alternative and no other faults in the circuit." ## Probability Semantics @@ -293,7 +334,7 @@ The Rust API lives in `pecos-qec`: ```rust use pecos_qec::fault_tolerance::fault_sampler::{ - build_fault_catalog, StochasticNoiseParams, + FaultCatalog, StochasticNoiseParams, }; use pecos_quantum::{Attribute, TickCircuit}; @@ -311,14 +352,20 @@ circuit.set_meta( Attribute::String(r#"[{"records":[-1]}]"#.into()), ); +// Structural catalog (no noise): +let mut catalog = FaultCatalog::from_circuit(&circuit).unwrap(); + +// Parameterize: let noise = StochasticNoiseParams { p1: 0.03, p2: 0.0, p_meas: 0.01, p_prep: 0.0, }; +catalog.with_noise(&noise); -let catalog = build_fault_catalog(&circuit, &noise).unwrap(); +// Or one-shot convenience: +// let catalog = build_fault_catalog(&circuit, &noise).unwrap(); ``` Iterate locations and alternatives: @@ -336,10 +383,11 @@ for loc in &catalog.locations { for fault in &loc.faults { println!( - " {:?} dets={:?} obs={:?} p_alt={}", + " {:?} dets={:?} obs={:?} tracked={:?} p_alt={}", fault.kind, fault.affected_detectors, fault.affected_observables, + fault.affected_tracked_ops, fault.absolute_probability ); } @@ -362,20 +410,96 @@ for event in catalog.fault_configurations(2) { ``` The Rust iterator borrows the catalog and does not materialize all -configurations up front. +configurations up front. On an unparameterized catalog, `fault_configurations(k)` +for k > 0 yields nothing (all probabilities are zero). + +## Fault Anatomy Exploration + +The structural catalog (no noise needed) lets you explore every fault event: + +```python +catalog = fault_catalog(circuit) + +# What faults can flip detector D3? +for loc in catalog: + for alt in loc.faults: + if 3 in alt.detectors: + print(f"D3 flipped by {alt.pauli} at {loc.gate_type}({loc.qubits})") + +# Find undetectable weight-2 logical errors: +catalog.with_noise(p1=0.01, p2=0.05, p_meas=0.01, p_prep=0.01) +for config in catalog.fault_configurations(2): + if config.observables and not config.detectors: + print(f"Undetectable: locations {config.location_indices}") +``` + +## Tracked Operators + +Tracked operators are Pauli operators that the catalog monitors for +anticommutation with fault events. Unlike observables, they have no +measurement records -- they are detected by forward Pauli propagation. + +Add tracked operators to a circuit via `pauli_operator`: + +```python +from pecos.quantum import PauliString + +circuit.pauli_operator(PauliString.from_str("X0 X1 X2"), label="logical_X") +``` + +Each `FaultAlternative` then has a `tracked_ops` field listing which tracked +operators are flipped by that fault. This is useful for studying logical +operator propagation without requiring measurement. + +## Raw Measurement Sampling + +The `meas_sampling()` backend in `sim_neo` uses the fault catalog internally +to produce raw measurement bitstrings: + +```python +from pecos_rslib_exp import sim_neo, meas_sampling, depolarizing + +result = ( + sim_neo(circuit) + .quantum(meas_sampling()) + .noise(depolarizing().p1(0.001).p2(0.01).p_meas(0.005).p_prep(0.005)) + .shots(10000) + .seed(42) + .run() +) + +# result[shot] gives measurement outcomes for each shot +for shot in range(len(result)): + measurements = list(result[shot]) +``` + +The sampling architecture: +- **Ideal values** from symbolic stabilizer simulation (respects measurement + correlations across resets) +- **Physical faults** from geometric skip sampling (O(fired events) per shot) +- Raw measurement = ideal XOR faults + +This is fast (millions of shots per second at small distances) and produces +the same measurement format as gate-by-gate stabilizer simulation. ## Common Pitfalls - `fault.absolute_probability` is `p_i / k_i`, not a full-circuit event probability. -- Empty-effect locations are real physical mechanisms and must remain in the - catalog for normalization. +- Empty-effect alternatives (no measurements flipped) are real -- they + represent Pauli errors that commute with subsequent measurements. They + must stay in the catalog for the correct uniform denominator. - `catalog.fault_configurations(k)` means exactly `k` distinct physical - locations fire, not at most `k`. + locations fire, not at most `k`. On an unparameterized catalog, k > 0 + yields nothing (zero probabilities). - Detector and observable metadata must be correct before building the catalog. Missing boundary detectors can make a correct decoder appear to fail. -- The current catalog models the supported stochastic channels in - `StochasticNoiseParams`: `p1`, `p2`, `p_meas`, and `p_prep`. +- `with_noise()` mutates the catalog in place. Previously held Python + references to locations and faults update automatically. Decoders and + samplers do NOT update -- they are snapshots. +- The structural catalog includes ALL locations even when a channel + probability is zero. Use `to_mechanisms()` to get only the nonzero + mechanisms for raw sampling. ## Larger Example From 40c7eb35fb5e324798e413d6debc4f7b90fe5467 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 07:26:55 -0600 Subject: [PATCH 060/125] Fix doc test blocks: merge split examples, add continuation markers, make blocks runnable --- docs/user-guide/fault-catalog.md | 46 +++++++++++-------- python/quantum-pecos/tests/docs/conftest.py | 2 +- .../tests/user_guide_fault_catalog.rs | 41 +++++++++++++++++ .../tests/user_guide_fault_tolerance.rs | 2 +- 4 files changed, 69 insertions(+), 22 deletions(-) create mode 100644 python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_catalog.rs diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index c14ea8f17..8ff58a414 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -32,8 +32,9 @@ exploration, or as a reusable base for parameter sweeps. **Parameterized (with noise):** fills in probabilities based on a stochastic noise model. Use this for sampling, decoding, and probability-weighted queries. + ```python -from pecos.quantum import TickCircuit +from pecos.quantum import PauliString, TickCircuit from pecos_rslib_exp import depolarizing, fault_catalog circuit = TickCircuit() @@ -65,6 +66,7 @@ structural fields like `affected_detectors` will be empty, but The expensive work (Pauli propagation, detector mapping) is done once during construction. Changing noise is cheap -- it just updates probability fields: + ```python catalog = fault_catalog(circuit) @@ -84,6 +86,7 @@ update existing decoders or plans. The returned object is sequence-like: + ```python print(len(catalog)) print(catalog[0]) @@ -157,8 +160,6 @@ noise is re-parameterized. Example: ```python -from pecos.quantum import PauliString - for loc in catalog: for fault in loc.faults: print(f" {fault.kind}: {fault.pauli}") @@ -193,8 +194,10 @@ configuration_probability For a single selected alternative at location `i`, the full event probability is: ```python -event_probability = fault.absolute_probability +selected_location_index = 0 +fault = catalog[selected_location_index].faults[0] +event_probability = fault.absolute_probability for j, loc in enumerate(catalog.locations): if j != selected_location_index: event_probability *= loc.no_fault_probability @@ -206,7 +209,8 @@ Use `catalog.fault_configurations(k)` to lazily iterate every configuration where exactly `k` distinct locations fire and one alternative is chosen from each selected location. -For `k = 0`, the iterator yields exactly one no-fault configuration: +For `k = 0`, the iterator yields exactly one no-fault configuration. Its +probability is the product of every location's `no_fault_probability`: ```python configs = list(catalog.fault_configurations(0)) @@ -219,12 +223,7 @@ assert no_fault.measurements == [] assert no_fault.detectors == [] assert no_fault.observables == [] assert no_fault.selected_probability == 1.0 -``` - -The no-fault configuration probability is the product of every location's -`no_fault_probability`: -```python expected = 1.0 for loc in catalog.locations: expected *= loc.no_fault_probability @@ -306,12 +305,9 @@ decoder = {} for syndrome, logical_weights in table.items(): best_logical = max(logical_weights.items(), key=lambda item: item[1])[0] decoder[syndrome] = best_logical -``` -To apply the decoder to an enumerated event, XOR the event's logical class with -the selected correction: -```python +# Apply the decoder: XOR the event's logical class with the correction def xor_sorted(a, b): out = set(a) for item in b: @@ -420,11 +416,11 @@ The structural catalog (no noise needed) lets you explore every fault event: ```python catalog = fault_catalog(circuit) -# What faults can flip detector D3? +# What faults can flip detector D0? for loc in catalog: for alt in loc.faults: - if 3 in alt.detectors: - print(f"D3 flipped by {alt.pauli} at {loc.gate_type}({loc.qubits})") + if 0 in alt.detectors: + print(f"D0 flipped by {alt.pauli} at {loc.gate_type}({loc.qubits})") # Find undetectable weight-2 logical errors: catalog.with_noise(p1=0.01, p2=0.05, p_meas=0.01, p_prep=0.01) @@ -442,9 +438,19 @@ measurement records -- they are detected by forward Pauli propagation. Add tracked operators to a circuit via `pauli_operator`: ```python -from pecos.quantum import PauliString - -circuit.pauli_operator(PauliString.from_str("X0 X1 X2"), label="logical_X") +tc2 = TickCircuit() +tc2.tick().h([0, 1]) +tc2.tick().mz([0, 1]) +tc2.set_meta("num_measurements", "2") +tc2.set_meta("detectors", "[]") +tc2.set_meta("observables", "[]") +tc2.pauli_operator(PauliString.from_str("XX"), label="logical_X") + +cat2 = fault_catalog(tc2, p1=0.01, p2=0.0, p_meas=0.01, p_prep=0.0) +for loc in cat2: + for alt in loc.faults: + if alt.tracked_ops: + print(f"{alt.pauli} flips tracked ops {alt.tracked_ops}") ``` Each `FaultAlternative` then has a `tracked_ops` field listing which tracked diff --git a/python/quantum-pecos/tests/docs/conftest.py b/python/quantum-pecos/tests/docs/conftest.py index 7a5ed3ca1..354dada23 100644 --- a/python/quantum-pecos/tests/docs/conftest.py +++ b/python/quantum-pecos/tests/docs/conftest.py @@ -63,7 +63,7 @@ def cuda_check() -> bool: @pytest.fixture(autouse=True) -def restore_cwd(): +def restore_cwd(): # noqa: ANN201 """Restore the current working directory after each test. Some tests (e.g., WASM examples) change the working directory, diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_catalog.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_catalog.rs new file mode 100644 index 000000000..18e97a7db --- /dev/null +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_catalog.rs @@ -0,0 +1,41 @@ +//! Auto-generated Rust tests from user-guide/fault-catalog.md +//! DO NOT EDIT - Generated by scripts/docs/generate_doc_tests.py +#![allow(unused_imports, unused_variables, unused_mut, unused_assignments, dead_code, non_snake_case)] + + + +#[test] +fn test_user_guide_fault_catalog_rust_1() { + use pecos_quantum::{Attribute, TickCircuit}; + use pecos_qec::fault_tolerance::fault_sampler::{ +FaultCatalog, StochasticNoiseParams, +}; + let mut circuit = TickCircuit::new(); + circuit.tick().h(&[0]); + circuit.tick().mz(&[0]); + + circuit.set_meta("num_measurements", Attribute::String("1".into())); + circuit.set_meta( + "detectors", + Attribute::String(r#"[{"records":[-1]}]"#.into()), + ); + circuit.set_meta( + "observables", + Attribute::String(r#"[{"records":[-1]}]"#.into()), + ); + + // Structural catalog (no noise): + let mut catalog = FaultCatalog::from_circuit(&circuit).unwrap(); + + // Parameterize: + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }; + catalog.with_noise(&noise); + + // Or one-shot convenience: + // let catalog = build_fault_catalog(&circuit, &noise).unwrap(); +} diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_tolerance.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_tolerance.rs index 814cc31d6..442214c2f 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_tolerance.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_tolerance.rs @@ -189,7 +189,7 @@ fn test_user_guide_fault_tolerance_rust_8() -> Result<(), Box Date: Sat, 9 May 2026 07:30:08 -0600 Subject: [PATCH 061/125] Improve fault catalog tutorial: quick start, real-world entry point, section framing --- docs/user-guide/fault-catalog.md | 69 +++++++++++++++++++++++++++----- 1 file changed, 60 insertions(+), 9 deletions(-) diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index 8ff58a414..c54569ccd 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -1,8 +1,54 @@ # Fault Catalog and Measurement Sampling -The fault catalog exposes every possible physical fault event in a -`TickCircuit`: what Pauli error occurs at each gate, which measurements flip, -which detectors fire, which observables flip, and which tracked operators are +## Quick start + +If you have a surface code and want to simulate noisy measurements: + + +```python +from pecos.qec.surface import SurfacePatch +from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model +from pecos_rslib_exp import sim_neo, meas_sampling, depolarizing + +patch = SurfacePatch.create(distance=3) +tc = _build_surface_tick_circuit_for_native_model(patch, rounds=6, basis="Z") + +result = ( + sim_neo(tc) + .quantum(meas_sampling()) + .noise(depolarizing().p1(0.001).p2(0.01).p_meas(0.005).p_prep(0.005)) + .shots(10000) + .seed(42) + .run() +) + +# result[shot] gives measurement outcomes for each shot +print(f"{len(result)} shots, {len(result[0])} measurements each") +``` + +If you want to inspect what faults are possible in that circuit: + + +```python +from pecos_rslib_exp import fault_catalog + +# Build structural catalog (no noise commitment): +catalog = fault_catalog(tc) +print(f"{len(catalog)} fault locations") + +# Parameterize to get probabilities: +catalog.with_noise(p1=0.001, p2=0.01, p_meas=0.005, p_prep=0.005) +``` + +The rest of this tutorial uses a small hand-built circuit to explain the +concepts. Everything works the same way with surface codes or any other +`TickCircuit`. + +## What is the fault catalog? + +The fault catalog exposes every possible physical fault event in a circuit: +what Pauli error occurs at each gate, which measurements flip, which +detectors fire, which observables flip, and which tracked operators are affected. It serves two purposes: @@ -174,6 +220,9 @@ probability of "this alternative and no other faults in the circuit." ## Probability Semantics +Understanding probabilities matters when you are building decoders, computing +thresholds, or verifying that a noise model produces the expected error rates. + For location `i`: ```text @@ -205,9 +254,10 @@ for j, loc in enumerate(catalog.locations): ## Lazy k-Fault Configurations -Use `catalog.fault_configurations(k)` to lazily iterate every configuration -where exactly `k` distinct locations fire and one alternative is chosen from -each selected location. +Use `catalog.fault_configurations(k)` to enumerate every way exactly `k` +faults can occur simultaneously. This is the foundation for building lookup +decoders, computing truncated ML tables, and analyzing multi-fault error +patterns. For `k = 0`, the iterator yields exactly one no-fault configuration. Its probability is the product of every location's `no_fault_probability`: @@ -259,9 +309,10 @@ print(first.faults[0] is first.locations[0].faults[first.alternative_indices[0]] ## XOR Parity -When multiple alternatives are selected, effects combine by XOR parity. If two -faults flip the same detector, that detector cancels from the combined -configuration. +When multiple faults occur simultaneously, their effects combine by XOR parity. +If two faults flip the same detector, that detector cancels. This is fundamental +to QEC -- it's why weight-2 errors can be undetectable even when each individual +fault triggers detectors. ```python for event in catalog.fault_configurations(2): From 4299698c0f835c6fcc606dc75d4a265c3f502a05 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 07:52:02 -0600 Subject: [PATCH 062/125] Fix tutorial issues from Codex review: API mismatch, tracked-op example, pitfalls --- Cargo.lock | 401 +++++++---------- docs/user-guide/fault-catalog.md | 34 +- uv.lock | 749 +++++++++++++++---------------- 3 files changed, 541 insertions(+), 643 deletions(-) diff --git a/Cargo.lock b/Cargo.lock index 8c65842b6..651fbb564 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -130,7 +130,7 @@ version = "1.1.5" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "40c48f72fd53cd289104fc64099abca73db4166ad86ea0b4341abe65af83dadc" dependencies = [ - "windows-sys 0.60.2", + "windows-sys 0.61.2", ] [[package]] @@ -141,7 +141,7 @@ checksum = "291e6a250ff86cd4a820112fb8898808a366d8f9f58ce16d1f538353ad55747d" dependencies = [ "anstyle", "once_cell_polyfill", - "windows-sys 0.60.2", + "windows-sys 0.61.2", ] [[package]] @@ -375,7 +375,7 @@ dependencies = [ "rand 0.10.1", "rand_xoshiro 0.8.0", "rapidhash", - "wide 1.3.0", + "wide 1.4.0", ] [[package]] @@ -619,9 +619,9 @@ dependencies = [ [[package]] name = "cargo-platform" -version = "0.3.2" +version = "0.3.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "87a0c0e6148f11f01f32650a2ea02d532b2ad4e81d8bd41e6e565b5adc5e6082" +checksum = "dd0061da739915fae12ea00e16397555ed4371a6bb285431aab930f61b0aa4ba" dependencies = [ "serde", "serde_core", @@ -649,9 +649,9 @@ checksum = "37b2a672a2cb129a2e41c10b1224bb368f9f37a2b16b612598138befd7b37eb5" [[package]] name = "cc" -version = "1.2.60" +version = "1.2.62" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "43c5703da9466b66a946814e1adf53ea2c90f10063b86290cc9eb67ce3478a20" +checksum = "a1dce859f0832a7d088c4f1119888ab94ef4b5d6795d1ce05afb7fe159d79f98" dependencies = [ "find-msvc-tools", "jobserver", @@ -659,12 +659,6 @@ dependencies = [ "shlex", ] -[[package]] -name = "cesu8" -version = "1.1.0" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "6d43a04d8753f35258c91f8ec639f792891f748a1edbd759cf1dcea3382ad83c" - [[package]] name = "cexpr" version = "0.6.0" @@ -799,9 +793,9 @@ dependencies = [ [[package]] name = "clap_complete" -version = "4.6.2" +version = "4.6.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "3ff7a1dccbdd8b078c2bdebff47e404615151534d5043da397ec50286816f9cb" +checksum = "660c0520455b1013b9bcb0393d5f643d7e4454fb69c915b8d6d2aa0e9a45acc3" dependencies = [ "clap 4.6.1", ] @@ -1100,9 +1094,9 @@ dependencies = [ [[package]] name = "crc-catalog" -version = "2.4.0" +version = "2.5.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "19d374276b40fb8bbdee95aef7c7fa6b5316ec764510eb64b8dd0e2ed0d7e7f5" +checksum = "217698eaf96b4a3f0bc4f3662aaa55bdf913cd54d7204591faa790070c6d0853" [[package]] name = "crc32fast" @@ -1490,9 +1484,9 @@ dependencies = [ [[package]] name = "digest" -version = "0.11.2" +version = "0.11.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "4850db49bf08e663084f7fb5c87d202ef91a3907271aff24a94eb97ff039153c" +checksum = "f1dd6dbb5841937940781866fa1281a1ff7bd3bf827091440879f9994983d5c2" dependencies = [ "block-buffer 0.12.0", "const-oid", @@ -1527,7 +1521,7 @@ dependencies = [ "libc", "option-ext", "redox_users 0.5.2", - "windows-sys 0.60.2", + "windows-sys 0.61.2", ] [[package]] @@ -1702,7 +1696,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb" dependencies = [ "libc", - "windows-sys 0.52.0", + "windows-sys 0.61.2", ] [[package]] @@ -1713,13 +1707,12 @@ checksum = "9f1f227452a390804cdb637b74a86990f2a7d7ba4b7d5693aac9b4dd6defd8d6" [[package]] name = "filetime" -version = "0.2.27" +version = "0.2.28" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "f98844151eee8917efc50bd9e8318cb963ae8b297431495d3f758616ea5c57db" +checksum = "2d5b2eef6fafbf69f877e55509ce5b11a760690ac9700a2921be067aa6afaef6" dependencies = [ "cfg-if", "libc", - "libredox", ] [[package]] @@ -2234,6 +2227,7 @@ dependencies = [ "allocator-api2", "equivalent", "foldhash 0.1.5", + "rayon", ] [[package]] @@ -2251,9 +2245,9 @@ dependencies = [ [[package]] name = "hashbrown" -version = "0.17.0" +version = "0.17.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "4f467dd6dccf739c208452f8014c75c18bb8301b050ad1cfb27153803edb0f51" +checksum = "ed5909b6e89a2db4456e54cd5f673791d7eca6732202bbf2a9cc504fe2f9b84a" [[package]] name = "heapz" @@ -2488,9 +2482,9 @@ dependencies = [ [[package]] name = "hybrid-array" -version = "0.4.10" +version = "0.4.11" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "3944cf8cf766b40e2a1a333ee5e9b563f854d5fa49d6a8ca2764e97c6eddb214" +checksum = "08d46837a0ed51fe95bd3b05de33cd64a1ee88fc797477ca48446872504507c5" dependencies = [ "typenum", ] @@ -2684,9 +2678,9 @@ dependencies = [ [[package]] name = "idna_adapter" -version = "1.2.1" +version = "1.2.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "3acae9609540aa318d1bc588455225fb2085b9ed0c4f6bd0d9d5bcd86f1a0344" +checksum = "cb68373c0d6620ef8105e855e7745e18b0d00d3bdb07fb532e434244cdb9a714" dependencies = [ "icu_normalizer", "icu_properties", @@ -2700,7 +2694,6 @@ checksum = "bd070e393353796e801d209ad339e89596eb4c8d430d18ede6a1cced8fafbd99" dependencies = [ "autocfg", "hashbrown 0.12.3", - "rayon", "serde", ] @@ -2711,7 +2704,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "d466e9454f08e4a911e14806c24e16fba1b4c121d1ea474396f396069cf949d9" dependencies = [ "equivalent", - "hashbrown 0.17.0", + "hashbrown 0.17.1", + "rayon", "serde", "serde_core", ] @@ -2790,16 +2784,6 @@ version = "2.12.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "d98f6fed1fde3f8c21bc40a1abb88dd75e67924f9cffc3ef95607bad8017f8e2" -[[package]] -name = "iri-string" -version = "0.7.12" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "25e659a4bb38e810ebc252e53b5814ff908a8c58c2a9ce2fae1bbec24cbf4e20" -dependencies = [ - "memchr", - "serde", -] - [[package]] name = "is-terminal" version = "0.4.17" @@ -2808,7 +2792,7 @@ checksum = "3640c1c38b8e4e43584d8df18be5fc6b0aa314ce6ebf51b53313d4306cca8e46" dependencies = [ "hermit-abi 0.5.2", "libc", - "windows-sys 0.52.0", + "windows-sys 0.61.2", ] [[package]] @@ -2852,9 +2836,9 @@ checksum = "8f42a60cbdf9a97f5d2305f08a87dc4e09308d1276d28c869c684d7777685682" [[package]] name = "jiff" -version = "0.2.23" +version = "0.2.24" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "1a3546dc96b6d42c5f24902af9e2538e82e39ad350b0c766eb3fbf2d8f3d8359" +checksum = "f00b5dbd620d61dfdcb6007c9c1f6054ebd75319f163d886a9055cec1155073d" dependencies = [ "jiff-static", "log", @@ -2865,9 +2849,9 @@ dependencies = [ [[package]] name = "jiff-static" -version = "0.2.23" +version = "0.2.24" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "2a8c8b344124222efd714b73bb41f8b5120b27a7cc1c75593a6ff768d9d05aa4" +checksum = "e000de030ff8022ea1da3f466fbb0f3a809f5e51ed31f6dd931c35181ad8e6d7" dependencies = [ "proc-macro2", "quote", @@ -2876,18 +2860,32 @@ dependencies = [ [[package]] name = "jni" -version = "0.21.1" +version = "0.22.4" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "1a87aa2bb7d2af34197c04845522473242e1aa17c12f4935d5856491a7fb8c97" +checksum = "5efd9a482cf3a427f00d6b35f14332adc7902ce91efb778580e180ff90fa3498" dependencies = [ - "cesu8", "cfg-if", "combine", - "jni-sys 0.3.1", + "jni-macros", + "jni-sys 0.4.1", "log", - "thiserror 1.0.69", + "simd_cesu8", + "thiserror 2.0.18", "walkdir", - "windows-sys 0.45.0", + "windows-link", +] + +[[package]] +name = "jni-macros" +version = "0.22.4" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "a00109accc170f0bdb141fed3e393c565b6f5e072365c3bd58f5b062591560a3" +dependencies = [ + "proc-macro2", + "quote", + "rustc_version", + "simd_cesu8", + "syn 2.0.117", ] [[package]] @@ -2930,9 +2928,9 @@ dependencies = [ [[package]] name = "js-sys" -version = "0.3.95" +version = "0.3.98" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "2964e92d1d9dc3364cae4d718d93f227e3abb088e747d92e0395bfdedf1c12ca" +checksum = "67df7112613f8bfd9150013a0314e196f4800d3201ae742489d999db2f979f08" dependencies = [ "cfg-if", "futures-util", @@ -3020,9 +3018,9 @@ checksum = "b3a6a8c165077efc8f3a971534c50ea6a1a18b329ef4a66e897a7e3a1494565f" [[package]] name = "libc" -version = "0.2.185" +version = "0.2.186" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "52ff2c0fe9bc6cb6b14a0592c2ff4fa9ceb83eea9db979b0487cd054946a2b8f" +checksum = "68ab91017fe16c622486840e4c83c9a37afeff978bd239b5293d61ece587de66" [[package]] name = "libloading" @@ -3056,10 +3054,7 @@ version = "0.1.16" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "e02f3bb43d335493c96bf3fd3a321600bf6bd07ed34bc64118e9293bdffea46c" dependencies = [ - "bitflags 2.11.1", "libc", - "plain", - "redox_syscall 0.7.4", ] [[package]] @@ -3295,9 +3290,9 @@ dependencies = [ [[package]] name = "naga" -version = "29.0.1" +version = "29.0.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "aa2630921705b9b01dcdd0b6864b9562ca3c1951eecd0f0c4f5f04f61e412647" +checksum = "0dd91265cc2454558f659b3b4b9640f0ddb8cc6521277f166b8a8c181c898079" dependencies = [ "arrayvec 0.7.6", "bit-set 0.9.1", @@ -3741,7 +3736,7 @@ checksum = "2621685985a2ebf1c516881c026032ac7deafcda1a2c9b7850dc81e3dfcb64c1" dependencies = [ "cfg-if", "libc", - "redox_syscall 0.5.18", + "redox_syscall", "smallvec", "windows-link", ] @@ -3754,9 +3749,9 @@ checksum = "57c0d7b74b563b49d38dae00a0c37d4d6de9b432382b2892f0574ddcae73fd0a" [[package]] name = "pastey" -version = "0.2.1" +version = "0.2.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b867cad97c0791bbd3aaa6472142568c6c9e8f71937e98379f584cfb0cf35bec" +checksum = "c5a797f0e07bdf071d15742978fc3128ec6c22891c31a3a931513263904c982a" [[package]] name = "pbr" @@ -3975,7 +3970,7 @@ dependencies = [ "pecos-random", "pecos-simulators", "rand 0.10.1", - "wide 1.3.0", + "wide 1.4.0", ] [[package]] @@ -4254,7 +4249,7 @@ dependencies = [ "serde_json", "smallvec", "thiserror 2.0.18", - "wide 1.3.0", + "wide 1.4.0", ] [[package]] @@ -4324,7 +4319,7 @@ dependencies = [ "rand_xoshiro 0.8.0", "random_tester", "rapidhash", - "wide 1.3.0", + "wide 1.4.0", ] [[package]] @@ -4498,7 +4493,7 @@ dependencies = [ "rand 0.10.1", "rayon", "smallvec", - "wide 1.3.0", + "wide 1.4.0", ] [[package]] @@ -4665,12 +4660,6 @@ version = "0.3.33" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "19f132c84eca552bf34cab8ec81f1c1dcc229b811638f9d283dceabe58c5569e" -[[package]] -name = "plain" -version = "0.2.3" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b4596b6d070b27117e987119b4dac604f3c58cfb0b191112e24771b2faeac1a6" - [[package]] name = "plotters" version = "0.3.7" @@ -4924,9 +4913,9 @@ dependencies = [ [[package]] name = "profiling" -version = "1.0.17" +version = "1.0.18" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "3eb8486b569e12e2c32ad3e204dbaba5e4b5b216e9367044f25f1dba42341773" +checksum = "3d595e54a326bc53c1c197b32d295e14b169e3cfeaa8dc82b529f947fba6bcf5" [[package]] name = "proptest" @@ -5379,15 +5368,6 @@ dependencies = [ "bitflags 2.11.1", ] -[[package]] -name = "redox_syscall" -version = "0.7.4" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "f450ad9c3b1da563fb6948a8e0fb0fb9269711c9c73d9ea1de5058c79c8d643a" -dependencies = [ - "bitflags 2.11.1", -] - [[package]] name = "redox_users" version = "0.4.6" @@ -5438,7 +5418,7 @@ checksum = "de2c52737737f8609e94f975dee22854a2d5c125772d4b1cf292120f4d45c186" dependencies = [ "allocator-api2", "bumpalo", - "hashbrown 0.17.0", + "hashbrown 0.17.1", "log", "rustc-hash 2.1.2", "smallvec", @@ -5530,9 +5510,9 @@ checksum = "19b30a45b0cd0bcca8037f3d0dc3421eaf95327a17cad11964fb8179b4fc4832" [[package]] name = "reqwest" -version = "0.13.2" +version = "0.13.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "ab3f43e3283ab1488b624b44b0e988d0acea0b3214e694730a055cb6b2efa801" +checksum = "62e0021ea2c22aed41653bc7e1419abb2c97e038ff2c33d0e1309e49a97deec0" dependencies = [ "base64", "bytes", @@ -5689,14 +5669,14 @@ dependencies = [ "errno", "libc", "linux-raw-sys", - "windows-sys 0.52.0", + "windows-sys 0.61.2", ] [[package]] name = "rustls" -version = "0.23.38" +version = "0.23.40" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "69f9466fb2c14ea04357e91413efb882e2a6d4a406e625449bc0a5d360d53a21" +checksum = "ef86cd5876211988985292b91c96a8f2d298df24e75989a43a3c73f2d4d8168b" dependencies = [ "aws-lc-rs", "once_cell", @@ -5720,9 +5700,9 @@ dependencies = [ [[package]] name = "rustls-pki-types" -version = "1.14.0" +version = "1.14.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "be040f8b0a225e40375822a563fa9524378b9d63112f53e19ffff34df5d33fdd" +checksum = "30a7197ae7eb376e574fe940d068c30fe0462554a3ddbe4eca7838e049c937a9" dependencies = [ "web-time", "zeroize", @@ -5730,9 +5710,9 @@ dependencies = [ [[package]] name = "rustls-platform-verifier" -version = "0.6.2" +version = "0.7.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "1d99feebc72bae7ab76ba994bb5e121b8d83d910ca40b36e0921f53becc41784" +checksum = "26d1e2536ce4f35f4846aa13bff16bd0ff40157cdb14cc056c7b14ba41233ba0" dependencies = [ "core-foundation", "core-foundation-sys", @@ -5746,7 +5726,7 @@ dependencies = [ "security-framework", "security-framework-sys", "webpki-root-certs", - "windows-sys 0.52.0", + "windows-sys 0.61.2", ] [[package]] @@ -5781,8 +5761,8 @@ checksum = "aaeee6f84153fd6f62507fc22bfe9499c8485075b44186dcbb918166ef75116f" dependencies = [ "fixedbitset 0.5.7", "foldhash 0.1.5", - "hashbrown 0.14.5", - "indexmap 1.9.3", + "hashbrown 0.15.5", + "indexmap 2.14.0", "ndarray 0.16.1", "num-traits", "petgraph 0.8.3", @@ -6059,9 +6039,9 @@ dependencies = [ [[package]] name = "serde_with" -version = "3.18.0" +version = "3.19.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "dd5414fad8e6907dbdd5bc441a50ae8d6e26151a03b1de04d89a5576de61d01f" +checksum = "f05839ce67618e14a09b286535c0d9c94e85ef25469b0e13cb4f844e5593eb19" dependencies = [ "base64", "chrono", @@ -6078,9 +6058,9 @@ dependencies = [ [[package]] name = "serde_with_macros" -version = "3.18.0" +version = "3.19.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "d3db8978e608f1fe7357e211969fd9abdcae80bac1ba7a3369bb7eb6b404eb65" +checksum = "cf2ebbe86054f9b45bc3881e865683ccfaccce97b9b4cb53f3039d67f355a334" dependencies = [ "darling", "proc-macro2", @@ -6124,7 +6104,7 @@ checksum = "446ba717509524cb3f22f17ecc096f10f4822d76ab5c0b9822c5f9c284e825f4" dependencies = [ "cfg-if", "cpufeatures 0.3.0", - "digest 0.11.2", + "digest 0.11.3", ] [[package]] @@ -6152,6 +6132,22 @@ version = "0.3.9" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "703d5c7ef118737c72f1af64ad2f6f8c5e1921f818cdcb97b8fe6fc69bf66214" +[[package]] +name = "simd_cesu8" +version = "1.1.1" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "94f90157bb87cddf702797c5dadfa0be7d266cdf49e22da2fcaa32eff75b2c33" +dependencies = [ + "rustc_version", + "simdutf8", +] + +[[package]] +name = "simdutf8" +version = "0.1.5" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "e3a9fe34e3e7a50316060351f37187a3f546bce95496156754b601a5fa71b76e" + [[package]] name = "similar" version = "2.7.0" @@ -6160,9 +6156,9 @@ checksum = "bbbb5d9659141646ae647b42fe094daf6c6192d1620870b449d9557f748b2daa" [[package]] name = "siphasher" -version = "1.0.2" +version = "1.0.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b2aa850e253778c88a04c3d7323b043aeda9d3e30d5971937c1855769763678e" +checksum = "8ee5873ec9cce0195efcb7a4e9507a04cd49aec9c83d0389df45b1ef7ba2e649" [[package]] name = "slab" @@ -6229,7 +6225,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "3a766e1110788c36f4fa1c2b71b387a7815aa65f88ce0229841826633d93723e" dependencies = [ "libc", - "windows-sys 0.60.2", + "windows-sys 0.61.2", ] [[package]] @@ -6471,7 +6467,7 @@ dependencies = [ "getrandom 0.4.2", "once_cell", "rustix", - "windows-sys 0.52.0", + "windows-sys 0.61.2", ] [[package]] @@ -6678,9 +6674,9 @@ dependencies = [ [[package]] name = "tket-json-rs" -version = "0.8.2" +version = "0.8.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "f94cdded1cb82aaf9e0c2508762753f72c60ce8c068853b8ecc6c1bcd21644b9" +checksum = "d411ed63c40c69f147fb2ecfae59bc9c8e15aee1f0d916fb07f37465a7a4b2e9" dependencies = [ "derive_more 2.1.1", "serde", @@ -6713,9 +6709,9 @@ dependencies = [ [[package]] name = "tokio" -version = "1.52.1" +version = "1.52.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b67dee974fe86fd92cc45b7a95fdd2f99a36a6d7b0d431a231178d3d670bbcc6" +checksum = "8fc7f01b389ac15039e4dc9531aa973a135d7a4135281b12d7c1bc79fd57fffe" dependencies = [ "bytes", "libc", @@ -6803,20 +6799,20 @@ dependencies = [ [[package]] name = "tower-http" -version = "0.6.8" +version = "0.6.10" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "d4e6559d53cc268e5031cd8429d05415bc4cb4aefc4aa5d6cc35fbf5b924a1f8" +checksum = "68d6fdd9f81c2819c9a8b0e0cd91660e7746a8e6ea2ba7c6b2b057985f6bcb51" dependencies = [ "bitflags 2.11.1", "bytes", "futures-util", "http", "http-body", - "iri-string", "pin-project-lite", "tower", "tower-layer", "tower-service", + "url", ] [[package]] @@ -6882,9 +6878,9 @@ checksum = "bc7d623258602320d5c55d1bc22793b57daff0ec7efc270ea7d55ce1d5f5471c" [[package]] name = "typenum" -version = "1.19.0" +version = "1.20.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "562d481066bde0658276a35467c4af00bdc6ee726305698a55b86e61d7ad82bb" +checksum = "40ce102ab67701b8526c123c1bab5cbe42d7040ccfd0f64af1a385808d2f43de" [[package]] name = "typetag" @@ -7002,9 +6998,9 @@ checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821" [[package]] name = "uuid" -version = "1.22.0" +version = "1.23.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "a68d3c8f01c0cfa54a75291d83601161799e4a89a39e0929f4b0354d88757a37" +checksum = "ddd74a9687298c6858e9b88ec8935ec45d22e8fd5e6394fa1bd4e99a87789c76" dependencies = [ "getrandom 0.4.2", "js-sys", @@ -7066,11 +7062,11 @@ checksum = "ccf3ec651a847eb01de73ccad15eb7d99f80485de043efb2f370cd654f4ea44b" [[package]] name = "wasip2" -version = "1.0.2+wasi-0.2.9" +version = "1.0.3+wasi-0.2.9" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "9517f9239f02c069db75e65f174b3da828fe5f5b945c4dd26bd25d89c03ebcf5" +checksum = "20064672db26d7cdc89c7798c48a0fdfac8213434a1186e5ef29fd560ae223d6" dependencies = [ - "wit-bindgen", + "wit-bindgen 0.57.1", ] [[package]] @@ -7079,14 +7075,14 @@ version = "0.4.0+wasi-0.3.0-rc-2026-01-06" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "5428f8bf88ea5ddc08faddef2ac4a67e390b88186c703ce6dbd955e1c145aca5" dependencies = [ - "wit-bindgen", + "wit-bindgen 0.51.0", ] [[package]] name = "wasm-bindgen" -version = "0.2.118" +version = "0.2.121" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "0bf938a0bacb0469e83c1e148908bd7d5a6010354cf4fb73279b7447422e3a89" +checksum = "49ace1d07c165b0864824eee619580c4689389afa9dc9ed3a4c75040d82e6790" dependencies = [ "cfg-if", "once_cell", @@ -7097,9 +7093,9 @@ dependencies = [ [[package]] name = "wasm-bindgen-futures" -version = "0.4.68" +version = "0.4.71" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "f371d383f2fb139252e0bfac3b81b265689bf45b6874af544ffa4c975ac1ebf8" +checksum = "96492d0d3ffba25305a7dc88720d250b1401d7edca02cc3bcd50633b424673b8" dependencies = [ "js-sys", "wasm-bindgen", @@ -7107,9 +7103,9 @@ dependencies = [ [[package]] name = "wasm-bindgen-macro" -version = "0.2.118" +version = "0.2.121" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = 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@@ dependencies = [ [[package]] name = "wasm-encoder" -version = "0.246.2" +version = "0.248.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "61fb705ce81adde29d2a8e99d87995e39a6e927358c91398f374474746070ef7" +checksum = "ac92cf547bc18d27ecc521015c08c353b4f18b84ab388bb6d1b6b682c620d9b6" dependencies = [ "leb128fmt", - "wasmparser 0.246.2", + "wasmparser 0.248.0", ] [[package]] @@ -7206,9 +7202,9 @@ dependencies = [ [[package]] name = "wasmparser" -version = "0.246.2" +version = "0.248.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "71cde4757396defafd25417cfb36aa3161027d06d865b0c24baaae229aac005d" +checksum = "aa4439c5eee9df71ee0c6efb37f63b1fcb1fec38f85f5142c54e7ed05d33091a" dependencies = [ "bitflags 2.11.1", "indexmap 2.14.0", @@ -7392,22 +7388,22 @@ dependencies = [ [[package]] name = "wast" -version = "246.0.2" +version = "248.0.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "fe3fe8e3bf88ad96d031b4181ddbd64634b17cb0d06dfc3de589ef43591a9a62" +checksum = "acc54622ed5a5cddafcdf152043f9d4aed54d4a653d686b7dfe874809fca99d7" dependencies = [ "bumpalo", "leb128fmt", "memchr", "unicode-width 0.2.2", - "wasm-encoder 0.246.2", + "wasm-encoder 0.248.0", ] [[package]] name = "wat" -version = "1.246.2" +version = "1.248.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "4bd7fda1199b94fff395c2d19a153f05dbe7807630316fa9673367666fd2ad8c" +checksum = "d75cd9e510603909748e6ebab89f27cd04472c1d9d85a3c88a7a6fc51a1a7934" dependencies = [ "wast", ] @@ -7432,9 +7428,9 @@ checksum = "323f4da9523e9a669e1eaf9c6e763892769b1d38c623913647bfdc1532fe4549" [[package]] name = "web-sys" -version = "0.3.95" +version = "0.3.98" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "4f2dfbb17949fa2088e5d39408c48368947b86f7834484e87b73de55bc14d97d" +checksum = "4b572dff8bcf38bad0fa19729c89bb5748b2b9b1d8be70cf90df697e3a8f32aa" dependencies = [ "js-sys", "wasm-bindgen", @@ -7461,9 +7457,9 @@ dependencies = [ [[package]] name = "wgpu" -version = "29.0.1" +version = "29.0.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "72c239a9a747bbd379590985bac952c2e53cb19873f7072b3370c6a6a8e06837" +checksum = "bb3feacc458f7bee8bc1737149b42b6c731aa461039a4264a67bb6681646b250" dependencies = [ "arrayvec 0.7.6", "bitflags 2.11.1", @@ -7491,9 +7487,9 @@ dependencies = [ [[package]] name = "wgpu-core" -version = "29.0.1" +version = "29.0.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "1e80ac6cf1895df6342f87d975162108f9d98772a0d74bc404ab7304ac29469e" +checksum = "02da3ad1b568337f25513b317870960ef87073ea0945502e44b864b67a8c77b7" dependencies = [ "arrayvec 0.7.6", "bit-set 0.9.1", @@ -7524,36 +7520,36 @@ dependencies = [ [[package]] name = "wgpu-core-deps-apple" -version = "29.0.0" +version = "29.0.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "43acd053312501689cd92a01a9638d37f3e41a5fd9534875efa8917ee2d11ac0" +checksum = "62e51b5447e144b3dbba4feb01f80f4fa21696fa0cd99afb2c3df1affd6fdb28" dependencies = [ "wgpu-hal", ] [[package]] name = "wgpu-core-deps-emscripten" -version = "29.0.0" +version = "29.0.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "ef043bf135cc68b6f667c55ff4e345ce2b5924d75bad36a47921b0287ca4b24a" +checksum = "3487cd6293a963bc5c0c0396f6a2192043c50003c07f4efdccbad3d90ec9d819" dependencies = [ "wgpu-hal", ] [[package]] name = "wgpu-core-deps-windows-linux-android" -version = "29.0.0" +version = "29.0.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "725d5c006a8c02967b6d93ef04f6537ec4593313e330cfe86d9d3f946eb90f28" +checksum = "1bfb01076d0aa08b0ba9bd741e178b5cc440f5abe99d9581323a4c8b5d1a1916" dependencies = [ "wgpu-hal", ] [[package]] name = "wgpu-hal" -version = "29.0.1" +version = "29.0.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "89a47aef47636562f3937285af4c44b4b5b404b46577471411cc5313a921da7e" +checksum = "31f8e1a9e7a8512f276f7c62e018c7fa8d60954303fed2e5750114332049193f" dependencies = [ "android_system_properties", "arrayvec 0.7.6", @@ -7600,13 +7596,14 @@ dependencies = [ "wgpu-types", "windows", "windows-core", + "windows-result", ] [[package]] name = "wgpu-naga-bridge" -version = "29.0.1" +version = "29.0.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "7b4684f4410da0cf95a4cb63bb5edaac022461dedb6adf0b64d0d9b5f6890d51" +checksum = "59c654c483f058800972c3645e95388a7eca31bf9fe1933bc20e036588a0be02" dependencies = [ "naga", "wgpu-types", @@ -7614,9 +7611,9 @@ dependencies = [ [[package]] name = "wgpu-types" -version = "29.0.1" +version = "29.0.3" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "ec2675540fb1a5cfa5ef122d3d5f390e2c75711a0b946410f2d6ac3a0f77d1f6" +checksum = "a9bcc31518a0e9735aefebedb5f7a9ef3ed1c42549c9f4c882fa9060ceaac639" dependencies = [ "bitflags 2.11.1", "bytemuck", @@ -7638,9 +7635,9 @@ dependencies = [ [[package]] name = "wide" -version = "1.3.0" +version = "1.4.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "c9479f84a757f819cfab37295955906479181395de83add28f74975fde083141" +checksum = "9a7714cd0430a663154667c74da5d09325c2387695bee18b3f7f72825aa3693a" dependencies = [ "bytemuck", "safe_arch 1.0.0", @@ -7668,7 +7665,7 @@ version = "0.1.11" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "c2a7b1c03c876122aa43f3020e6c3c3ee5c05081c9a00739faf7503aeba10d22" dependencies = [ - "windows-sys 0.52.0", + "windows-sys 0.61.2", ] [[package]] @@ -7778,15 +7775,6 @@ dependencies = [ "windows-link", ] -[[package]] -name = "windows-sys" -version = "0.45.0" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "75283be5efb2831d37ea142365f009c02ec203cd29a3ebecbc093d52315b66d0" -dependencies = [ - "windows-targets 0.42.2", -] - [[package]] name = "windows-sys" version = "0.52.0" @@ -7814,21 +7802,6 @@ dependencies = [ "windows-link", ] -[[package]] -name = "windows-targets" -version = "0.42.2" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "8e5180c00cd44c9b1c88adb3693291f1cd93605ded80c250a75d472756b4d071" -dependencies = [ - "windows_aarch64_gnullvm 0.42.2", - "windows_aarch64_msvc 0.42.2", - "windows_i686_gnu 0.42.2", - "windows_i686_msvc 0.42.2", - "windows_x86_64_gnu 0.42.2", - "windows_x86_64_gnullvm 0.42.2", - "windows_x86_64_msvc 0.42.2", -] - [[package]] name = "windows-targets" version = "0.52.6" @@ -7871,12 +7844,6 @@ dependencies = [ "windows-link", ] -[[package]] -name = "windows_aarch64_gnullvm" -version = "0.42.2" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "597a5118570b68bc08d8d59125332c54f1ba9d9adeedeef5b99b02ba2b0698f8" - [[package]] name = "windows_aarch64_gnullvm" version = "0.52.6" @@ -7889,12 +7856,6 @@ version = "0.53.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "a9d8416fa8b42f5c947f8482c43e7d89e73a173cead56d044f6a56104a6d1b53" -[[package]] -name = "windows_aarch64_msvc" -version = "0.42.2" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "e08e8864a60f06ef0d0ff4ba04124db8b0fb3be5776a5cd47641e942e58c4d43" - [[package]] name = "windows_aarch64_msvc" version = "0.52.6" @@ -7907,12 +7868,6 @@ version = "0.53.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "b9d782e804c2f632e395708e99a94275910eb9100b2114651e04744e9b125006" -[[package]] -name = "windows_i686_gnu" -version = "0.42.2" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "c61d927d8da41da96a81f029489353e68739737d3beca43145c8afec9a31a84f" - [[package]] name = "windows_i686_gnu" version = "0.52.6" @@ -7937,12 +7892,6 @@ version = "0.53.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "fa7359d10048f68ab8b09fa71c3daccfb0e9b559aed648a8f95469c27057180c" -[[package]] -name = "windows_i686_msvc" -version = "0.42.2" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "44d840b6ec649f480a41c8d80f9c65108b92d89345dd94027bfe06ac444d1060" - [[package]] name = "windows_i686_msvc" version = "0.52.6" @@ -7955,12 +7904,6 @@ version = "0.53.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "1e7ac75179f18232fe9c285163565a57ef8d3c89254a30685b57d83a38d326c2" -[[package]] -name = "windows_x86_64_gnu" -version = "0.42.2" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "8de912b8b8feb55c064867cf047dda097f92d51efad5b491dfb98f6bbb70cb36" - [[package]] name = "windows_x86_64_gnu" version = "0.52.6" @@ -7973,12 +7916,6 @@ version = "0.53.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "9c3842cdd74a865a8066ab39c8a7a473c0778a3f29370b5fd6b4b9aa7df4a499" -[[package]] -name = "windows_x86_64_gnullvm" -version = "0.42.2" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "26d41b46a36d453748aedef1486d5c7a85db22e56aff34643984ea85514e94a3" - [[package]] name = "windows_x86_64_gnullvm" version = "0.52.6" @@ -7991,12 +7928,6 @@ version = "0.53.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "0ffa179e2d07eee8ad8f57493436566c7cc30ac536a3379fdf008f47f6bb7ae1" -[[package]] -name = "windows_x86_64_msvc" -version = "0.42.2" -source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "9aec5da331524158c6d1a4ac0ab1541149c0b9505fde06423b02f5ef0106b9f0" - [[package]] name = "windows_x86_64_msvc" version = "0.52.6" @@ -8011,9 +7942,9 @@ checksum = "d6bbff5f0aada427a1e5a6da5f1f98158182f26556f345ac9e04d36d0ebed650" [[package]] name = "winnow" -version = "1.0.1" +version = "1.0.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "09dac053f1cd375980747450bfc7250c264eaae0583872e845c0c7cd578872b5" +checksum = "2ee1708bef14716a11bae175f579062d4554d95be2c6829f518df847b7b3fdd0" dependencies = [ "memchr", ] @@ -8027,6 +7958,12 @@ dependencies = [ "wit-bindgen-rust-macro", ] +[[package]] +name = "wit-bindgen" +version = "0.57.1" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "1ebf944e87a7c253233ad6766e082e3cd714b5d03812acc24c318f549614536e" + [[package]] name = "wit-bindgen-core" version = "0.51.0" diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index c54569ccd..c6362a4c7 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -11,7 +11,7 @@ from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_mode from pecos_rslib_exp import sim_neo, meas_sampling, depolarizing patch = SurfacePatch.create(distance=3) -tc = _build_surface_tick_circuit_for_native_model(patch, rounds=6, basis="Z") +tc = _build_surface_tick_circuit_for_native_model(patch, num_rounds=6, basis="Z") result = ( sim_neo(tc) @@ -295,7 +295,8 @@ For `k > 0`, each yielded `FaultConfiguration` has: | `selected_probability` | Product of selected `absolute_probability` values | | `configuration_probability` | Selected probability times no-fault probabilities for unselected locations | -The iterator is lazy: +The iterator is lazy -- it yields one configuration at a time without +materializing all combinations up front: ```python it = catalog.fault_configurations(1) @@ -303,8 +304,9 @@ first = next(it) print(first.location_indices) print(first.alternative_indices) -print(first.locations[0] is catalog.locations[first.location_indices[0]]) -print(first.faults[0] is first.locations[0].faults[first.alternative_indices[0]]) +print(first.detectors) +print(first.observables) +print(first.configuration_probability) ``` ## XOR Parity @@ -325,6 +327,11 @@ check the residual logical by XOR. ## Building a Small Lookup Table +This example builds a complete lookup table in Python by exhaustively +enumerating fault configurations. This is useful for understanding the API +and for small circuits. For larger codes, use the Rust `TargetedLookupDecoder` +which searches on-demand without precomputing all syndromes. + A lookup decoder table groups configuration probability by: ```text @@ -490,12 +497,13 @@ Add tracked operators to a circuit via `pauli_operator`: ```python tc2 = TickCircuit() -tc2.tick().h([0, 1]) -tc2.tick().mz([0, 1]) -tc2.set_meta("num_measurements", "2") +tc2.tick().h([0]) +tc2.tick().mz([0]) +tc2.set_meta("num_measurements", "1") tc2.set_meta("detectors", "[]") tc2.set_meta("observables", "[]") -tc2.pauli_operator(PauliString.from_str("XX"), label="logical_X") +# Track Z on qubit 0 -- X and Y faults after H anticommute with Z +tc2.pauli_operator(PauliString.from_str("Z"), label="track_Z0") cat2 = fault_catalog(tc2, p1=0.01, p2=0.0, p_meas=0.01, p_prep=0.0) for loc in cat2: @@ -547,16 +555,18 @@ the same measurement format as gate-by-gate stabilizer simulation. represent Pauli errors that commute with subsequent measurements. They must stay in the catalog for the correct uniform denominator. - `catalog.fault_configurations(k)` means exactly `k` distinct physical - locations fire, not at most `k`. On an unparameterized catalog, k > 0 - yields nothing (zero probabilities). + locations fire, not at most `k`. Only alternatives with positive + `absolute_probability` are yielded. On an unparameterized catalog, k > 0 + yields nothing. On a parameterized catalog with some channels zeroed, + locations from those channels are skipped. - Detector and observable metadata must be correct before building the catalog. Missing boundary detectors can make a correct decoder appear to fail. - `with_noise()` mutates the catalog in place. Previously held Python references to locations and faults update automatically. Decoders and samplers do NOT update -- they are snapshots. - The structural catalog includes ALL locations even when a channel - probability is zero. Use `to_mechanisms()` to get only the nonzero - mechanisms for raw sampling. + probability is zero. The `meas_sampling()` backend internally filters + zero-probability locations when building raw sampling mechanisms. ## Larger Example diff --git a/uv.lock b/uv.lock index 4ea9dd070..677eff7f2 100644 --- a/uv.lock +++ b/uv.lock @@ -3,11 +3,9 @@ revision = 3 requires-python = ">=3.10" resolution-markers = [ "python_full_version >= '3.14' and platform_machine == 'x86_64' and sys_platform == 'darwin'", - "python_full_version >= '3.12' and python_full_version < '3.14' and platform_machine == 'x86_64' and sys_platform == 'darwin'", - "python_full_version == '3.11.*' and platform_machine == 'x86_64' and sys_platform == 'darwin'", + "python_full_version >= '3.11' and python_full_version < '3.14' and platform_machine == 'x86_64' and sys_platform == 'darwin'", "(python_full_version >= '3.14' and platform_machine != 'x86_64') or (python_full_version >= '3.14' and sys_platform != 'darwin')", - "(python_full_version >= '3.12' and python_full_version < '3.14' and platform_machine != 'x86_64') or 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--git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index c6362a4c7..4df73ccf7 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -44,28 +44,21 @@ The rest of this tutorial uses a small hand-built circuit to explain the concepts. Everything works the same way with surface codes or any other `TickCircuit`. -## What is the fault catalog? - -The fault catalog exposes every possible physical fault event in a circuit: -what Pauli error occurs at each gate, which measurements flip, which -detectors fire, which observables flip, and which tracked operators are -affected. - -It serves two purposes: - -1. **Research tool** -- explore fault anatomy, build custom decoders, analyze - noise sensitivity, find undetectable errors, all without committing to a - noise model. -2. **Sampling infrastructure** -- parameterize with noise, then sample raw - measurements or enumerate fault configurations for decoding. - -The core model is: - -- each `FaultLocation` is an independent physical fault mechanism -- each location has one or more `FaultAlternative`s -- exactly one alternative is chosen when the location fires -- measurement, detector, observable, and tracked-operator effects combine by - XOR parity +Note: when using circuit builders like `SurfacePatch`, the detector and +observable metadata is set automatically. The hand-built examples below +set metadata explicitly via `set_meta` -- you normally don't need to write +JSON strings by hand. + +## Core model + +- Each `FaultLocation` is an independent physical fault mechanism (one per + noisy gate in the circuit). +- Each location has one or more `FaultAlternative`s (e.g., X/Y/Z for a + single-qubit depolarizing channel, 15 alternatives for two-qubit). +- When the location fires, exactly one alternative is chosen uniformly. +- Each alternative records which measurements, detectors, observables, and + tracked operators it flips. +- Multi-fault effects combine by XOR parity. ## Structural vs Parameterized Catalogs From 16252c8a89436178a2103725d3d4a62326ab8737 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 08:01:20 -0600 Subject: [PATCH 064/125] Fix tracked-operator tutorial example to produce visible output --- docs/user-guide/fault-catalog.md | 14 ++++++++------ .../quantum-pecos/tests/docs/rust_crate/Cargo.lock | 4 ++++ 2 files changed, 12 insertions(+), 6 deletions(-) diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index 4df73ccf7..bd0d9ae32 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -491,23 +491,25 @@ Add tracked operators to a circuit via `pauli_operator`: ```python tc2 = TickCircuit() tc2.tick().h([0]) -tc2.tick().mz([0]) -tc2.set_meta("num_measurements", "1") +tc2.set_meta("num_measurements", "0") tc2.set_meta("detectors", "[]") tc2.set_meta("observables", "[]") # Track Z on qubit 0 -- X and Y faults after H anticommute with Z tc2.pauli_operator(PauliString.from_str("Z"), label="track_Z0") -cat2 = fault_catalog(tc2, p1=0.01, p2=0.0, p_meas=0.01, p_prep=0.0) +cat2 = fault_catalog(tc2, p1=0.01, p2=0.0, p_meas=0.0, p_prep=0.0) for loc in cat2: for alt in loc.faults: if alt.tracked_ops: print(f"{alt.pauli} flips tracked ops {alt.tracked_ops}") +# Output: +# X_0 flips tracked ops [0] +# Y_0 flips tracked ops [0] ``` -Each `FaultAlternative` then has a `tracked_ops` field listing which tracked -operators are flipped by that fault. This is useful for studying logical -operator propagation without requiring measurement. +No measurement is needed -- the catalog detects that X and Y faults after H +anticommute with the tracked Z operator. This is useful for studying logical +operator propagation independently of measurement outcomes. ## Raw Measurement Sampling diff --git a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock index c56d77851..0e1c33d84 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock +++ b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock @@ -2706,6 +2706,8 @@ version = "0.2.0-dev.0" dependencies = [ "anyhow", "ndarray 0.17.2", + "pecos-random", + "rayon", "thiserror 2.0.18", ] @@ -2908,12 +2910,14 @@ dependencies = [ "ndarray 0.17.2", "pecos-core", "pecos-decoder-core", + "pecos-num", "pecos-quantum", "pecos-random", "pecos-simulators", "rand 0.10.1", "rand_core 0.10.0", "rayon", + "serde_json", "smallvec", "thiserror 2.0.18", "wide 1.2.0", From c0465b05d3b6c92b0d4d7d0b08616656728aed75 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 08:04:43 -0600 Subject: [PATCH 065/125] Add expect-output checks to fault catalog tutorial doc tests --- docs/user-guide/fault-catalog.md | 2 ++ 1 file changed, 2 insertions(+) diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index bd0d9ae32..bf36ca58b 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -464,6 +464,7 @@ for k > 0 yields nothing (all probabilities are zero). The structural catalog (no noise needed) lets you explore every fault event: + ```python catalog = fault_catalog(circuit) @@ -488,6 +489,7 @@ measurement records -- they are detected by forward Pauli propagation. Add tracked operators to a circuit via `pauli_operator`: + ```python tc2 = TickCircuit() tc2.tick().h([0]) From a3d3210bd05023486fd4fd7788451696cb8b3b5c Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 08:13:42 -0600 Subject: [PATCH 066/125] Add expect-output-block doc test marker with exact and ellipsis matching --- docs/user-guide/fault-catalog.md | 9 ++-- scripts/docs/generate_doc_tests.py | 78 +++++++++++++++++++++++++++++- 2 files changed, 81 insertions(+), 6 deletions(-) diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index bf36ca58b..4f315fb79 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -489,7 +489,7 @@ measurement records -- they are detected by forward Pauli propagation. Add tracked operators to a circuit via `pauli_operator`: - + ```python tc2 = TickCircuit() tc2.tick().h([0]) @@ -504,9 +504,10 @@ for loc in cat2: for alt in loc.faults: if alt.tracked_ops: print(f"{alt.pauli} flips tracked ops {alt.tracked_ops}") -# Output: -# X_0 flips tracked ops [0] -# Y_0 flips tracked ops [0] +``` +```output +X_0 flips tracked ops [0] +Y_0 flips tracked ops [0] ``` No measurement is needed -- the catalog detects that X and Y faults after H diff --git a/scripts/docs/generate_doc_tests.py b/scripts/docs/generate_doc_tests.py index d3d46ab4e..c24b5fb40 100755 --- a/scripts/docs/generate_doc_tests.py +++ b/scripts/docs/generate_doc_tests.py @@ -69,6 +69,8 @@ class CodeBlock: skip_if_no_cuda_rust: bool = False expect_error: str | None = None expect_output: str | None = None + expect_output_block: str | None = None + expect_output_mode: str = "exact" # "exact" or "ellipsis" test_name: str | None = None marks: list[str] = field(default_factory=list) is_continuation: bool = False @@ -196,6 +198,8 @@ def _parse_marker_comment(comment: str) -> dict: "skip_if_no_cuda_rust": False, "expect_error": None, "expect_output": None, + "expect_output_block": False, + "expect_output_mode": "exact", "test_name": None, "marks": [], "is_continuation": False, @@ -239,8 +243,14 @@ def _parse_marker_comment(comment: str) -> dict: result["expect_error"] = match.group(1).strip() result["skip"] = False # Don't skip, we want to test the error - # Check for expect-output - if "expect-output" in comment_lower: + # Check for expect-output-block (must check before expect-output substring match) + if "expect-output-block" in comment_lower: + result["expect_output_block"] = True + mode_match = re.search(r"expect-output-block:\s*(\w+)\s*-->", comment, re.IGNORECASE) + if mode_match: + result["expect_output_mode"] = mode_match.group(1).strip().lower() + # Check for expect-output (substring match) + elif "expect-output" in comment_lower: match = re.search(r"expect-output:\s*(.+?)\s*-->", comment, re.IGNORECASE) if match: result["expect_output"] = match.group(1).strip() @@ -381,6 +391,21 @@ def extract_code_blocks(file_path: Path, language: str = "python") -> list[CodeB block_skip = attrs["skip"] or doc_skip block_skip_reason = attrs["skip_reason"] or doc_skip_reason + # If expect-output-block, look for a ```output fence after this code block + output_block_text = None + output_mode = attrs["expect_output_mode"] + if attrs["expect_output_block"]: + after_fence = content[match.end():] + output_match = re.match(r"\s*```output\n(.*?)```", after_fence, re.DOTALL) + if output_match: + output_block_text = output_match.group(1).rstrip("\n") + else: + msg = ( + f"{file_path}:{line_number}: expect-output-block marker " + f"but no ```output fence found after code block" + ) + raise ValueError(msg) + block = CodeBlock( code=full_code, language=language, @@ -393,6 +418,8 @@ def extract_code_blocks(file_path: Path, language: str = "python") -> list[CodeB skip_if_no_cuda_rust=attrs["skip_if_no_cuda_rust"], expect_error=attrs["expect_error"], expect_output=attrs["expect_output"], + expect_output_block=output_block_text, + expect_output_mode=output_mode, test_name=attrs["test_name"], marks=attrs["marks"], is_continuation=attrs["is_continuation"], @@ -450,6 +477,8 @@ def generate_test_function(block: CodeBlock, file_stem: str) -> str: lines.extend(_generate_rust_exec_body(block)) elif block.expect_error: lines.extend(_generate_expect_error_body(block)) + elif block.expect_output_block is not None: + lines.extend(_generate_expect_output_block_body(block)) elif block.expect_output: lines.extend(_generate_expect_output_body(block)) elif _uses_guppy_decorator(block.code): @@ -751,6 +780,51 @@ def _generate_expect_output_body(block: CodeBlock) -> list[str]: return lines +def _generate_expect_output_block_body(block: CodeBlock) -> list[str]: + """Generate test body that checks stdout matches expected output exactly. + + Uses Python's doctest.OutputChecker for matching. Supports exact mode + (default) and ellipsis mode (``...`` skips variable parts). + """ + escaped_code = block.code.replace("\\", "\\\\").replace('"""', '\\"\\"\\"') + escaped_expected = block.expect_output_block.replace("\\", "\\\\").replace('"""', '\\"\\"\\"') + use_ellipsis = block.expect_output_mode == "ellipsis" + + lines = [ + " import doctest", + " import subprocess", + " import sys", + "", + ' code = """', + *[line.rstrip() for line in escaped_code.split("\n")], + '"""', + ' expected = """', + *[line.rstrip() for line in escaped_expected.split("\n")], + '"""', + "", + " result = subprocess.run(", + ' [sys.executable, "-c", code],', + " capture_output=True,", + " text=True,", + " timeout=30,", + " check=False,", + " )", + " if result.returncode != 0:", + ' pytest.fail(f"Code failed:\\n{result.stderr}")', + "", + " checker = doctest.OutputChecker()", + f" flags = doctest.ELLIPSIS if {use_ellipsis} else 0", + " if not checker.check_output(expected.strip(), result.stdout.strip(), flags):", + " diff = checker.output_difference(", + ' doctest.Example("", expected.strip()),', + " result.stdout.strip(),", + " flags,", + " )", + ' pytest.fail(f"Output mismatch:\\n{diff}")', + ] + return lines + + def generate_test_file(file_path: Path, blocks: list[CodeBlock]) -> str: """Generate a complete pytest test file for a markdown file.""" file_stem = _sanitize_name(file_path.stem) From 8f929bb275664d4f9ce615b4d8aa10ec8f42f08c Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 08:21:58 -0600 Subject: [PATCH 067/125] Move decoder-architecture design doc to pecos-docs, add output block checks, fix all doc tests --- docs/concepts/decoder-architecture.md | 206 -------------------------- docs/user-guide/fault-catalog.md | 7 +- 2 files changed, 6 insertions(+), 207 deletions(-) delete mode 100644 docs/concepts/decoder-architecture.md diff --git a/docs/concepts/decoder-architecture.md b/docs/concepts/decoder-architecture.md deleted file mode 100644 index 46f6b94f9..000000000 --- a/docs/concepts/decoder-architecture.md +++ /dev/null @@ -1,206 +0,0 @@ -# Decoder Architecture - -PECOS provides a layered decoder architecture for quantum error correction, -from simple memory experiments to logical algorithms with transversal gates -and real-time streaming decode. - -## Design Principles - -- **Composable**: any MWPM-compatible decoder can be used as an inner decoder -- **Budget-aware**: automatically adapts window size and overlap based on hardware timing constraints -- **Streaming**: accepts syndrome data round-by-round for real-time operation -- **Frame-tracking**: propagates Pauli corrections through transversal gate boundaries - -## Decoder Layers - -The architecture is layered, with each layer adding capability: - -``` -Layer 1: Inner Decoder (MWPM) - PyMatching, Fusion Blossom, Union-Find, ... - Input: graphlike DEM + syndrome - Output: observable correction bitmask - -Layer 2: Observable Subgraph Decoder (OSD) - Decomposes transversal-gate circuits into per-observable graphlike subgraphs - Input: full DEM (may have hyperedges) + syndrome + spatial coordinates - Output: observable correction bitmask - -Layer 3: Logical Algorithm Decoder - Adds frame propagation across transversal gate boundaries - Input: algorithm descriptor (segments + boundary gates) + syndrome - Output: correction at each decision point - -Layer 4: Logical Circuit Decoder (budget-aware) - Selects decode strategy based on hardware timing budget - Input: algorithm descriptor + budget + syndrome stream - Output: real-time corrections -``` - -## Layer 1: Inner Decoders - -Any decoder implementing the `ObservableDecoder` trait: - -| Decoder | Type | DEM Support | Accuracy | Speed | -|---------|------|-------------|----------|-------| -| PyMatching | MWPM | graphlike | baseline | fast | -| Fusion Blossom | MWPM | graphlike | ~baseline | fast (parallel) | -| Tesseract | A* search | any (hyperedges) | best | medium | -| BP+OSD | LDPC | any | good | slow | -| Union-Find | cluster | graphlike | good | fastest | -| MWPF | matching | graphlike | best | slow | - -MWPM decoders require **graphlike** (decomposed) DEMs where every mechanism -touches at most 2 detectors. Non-MWPM decoders can handle hyperedges directly. - -Use `decoder_dem_requirement(decoder_type)` to query what a decoder needs: - -```python -from pecos_rslib.qec import decoder_dem_requirement - -decoder_dem_requirement("pymatching") # "graphlike" -decoder_dem_requirement("tesseract") # "any" -``` - -## Layer 2: Observable Subgraph Decoder (OSD) - -**Problem**: Transversal gates (H, CX) create hyperedge mechanisms in the DEM -(3+ detectors flipping together). MWPM decoders cannot handle these. - -**Solution**: Proved by Serra-Peralta et al. and Cain et al. (2025): the -per-observable subgraph of a transversal-gate DEM is always graphlike. OSD -exploits this by: - -1. Classifying each detector by (logical_qubit, stabilizer_type) using spatial coordinates -2. For each observable, finding its observing region via boundary edges -3. Extracting a sub-DEM restricted to those detectors (guaranteed graphlike) -4. Running any MWPM decoder on each subgraph independently -5. Combining per-observable corrections via XOR - -```python -from pecos_rslib.qec import ObservableSubgraphDecoder - -# Build OSD with PyMatching as inner decoder -osd = ObservableSubgraphDecoder(dem_string, stab_coords, inner_decoder="pymatching") - -# Decode a syndrome -obs_correction = osd.decode(syndrome) -``` - -### Spatial Coordinates - -OSD requires detector spatial coordinates to classify detectors. These -are typically embedded in the DEM as `detector(x, y, t) D_i` annotations. -The `stab_coords` parameter maps each stabilizer to its (x, y) position -and type (X or Z). - -## Layer 3: Logical Algorithm Decoder - -Adds Pauli frame propagation at transversal gate boundaries: - -| Gate | X frame | Z frame | -|------|---------|---------| -| Hadamard | X <-> Z | Z <-> X | -| CNOT | ctrl X -> target X | target Z -> ctrl Z | -| S gate | X -> X*Z | Z unchanged | -| T injection | Decision point | ancilla Z -> data Z | - -T-gate injection is the only point requiring a real-time decode decision. -All other gates just propagate the frame algebraically. - -```python -from pecos_rslib.qec import LogicalAlgorithmDecoder - -# Build from algorithm descriptor -decoder = LogicalAlgorithmDecoder(descriptor, inner_decoder="pymatching") -correction = decoder.decode(full_syndrome) -``` - -## Layer 4: Budget-Aware Decoding - -Different hardware platforms have different timing constraints: - -| Platform | Reaction time | Strategy | -|----------|--------------|----------| -| Superconducting | ~1 us | Minimal windows, no overlap | -| Neutral atom | ~1 ms | d-round windows, d/2 overlap | -| Ion trap | ~10 ms | Large windows, full overlap | -| Offline | unlimited | Full-circuit decode | - -The `DecodeBudget` automatically selects window size and overlap: - -```python -from pecos_rslib.qec import LogicalCircuitDecoder - -# Budget-aware: automatically selects strategy -decoder = LogicalCircuitDecoder( - descriptor, - budget="neutral_atom", # or "superconducting", "unlimited" - inner_decoder="pymatching", -) -``` - -## Windowed Decoding - -For deep circuits, the observing region can span too many rounds, degrading -accuracy. Windowed decoding splits the time axis: - -- **Non-overlapping**: each detector in exactly one window (fastest) -- **Overlapping**: buffer zones extend beyond core for matching context (more accurate) -- **Streaming**: commit previous windows and slide forward (real-time) - -The `WindowedOsdDecoder` implements windowed OSD: - -```python -from pecos_rslib.qec import WindowedOsdDecoder - -decoder = WindowedOsdDecoder( - dem_string, - stab_coords, - inner_decoder="pymatching", - step=8, # core window size in time steps - buffer=4, # buffer on each side -) -``` - -## Streaming Decode - -For real-time operation, the `StreamingDecoder` trait accepts syndrome -data round-by-round: - -```rust -// Rust API -trait StreamingDecoder { - fn feed_round(&mut self, round: usize, detectors: &[(u32, u8)]) -> Result; - fn flush(&mut self) -> Result; - fn accumulated_obs(&self) -> u64; -} -``` - -The `CommittedOsd` implements streaming with software commitment (Cain et al.): -committed detectors are masked in future decodes, preventing past decisions -from being revisited. - -## DEM Generation for Decoders - -The choice of DEM generation method affects decoder accuracy: - -| Method | Coherent noise | PyMatching LER | Tesseract LER | -|--------|---------------|----------------|---------------| -| `from_circuit` (stochastic only) | ignores | baseline | baseline | -| `coherent_dem_decomposed` (EEG) | handles | 17% better | 10% better | -| `noise_characterization` (EEG) | handles | 17% better | 10% better | - -For circuits with coherent noise (idle Z-rotations), use `coherent_dem_decomposed` -or `noise_characterization` which produce properly decomposed DEMs with -Heisenberg-exact probabilities. - -## Summary - -The decoder architecture separates concerns cleanly: - -- **Inner decoders** solve the matching/search problem on graphlike DEMs -- **OSD** handles transversal gate hyperedges via proven subgraph decomposition -- **Frame propagation** tracks corrections through gate boundaries algebraically -- **Budgets** adapt decode strategy to hardware constraints automatically -- **Streaming** enables real-time operation via round-by-round feeding diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index 4f315fb79..e966f7e2c 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -464,7 +464,7 @@ for k > 0 yields nothing (all probabilities are zero). The structural catalog (no noise needed) lets you explore every fault event: - + ```python catalog = fault_catalog(circuit) @@ -480,6 +480,11 @@ for config in catalog.fault_configurations(2): if config.observables and not config.detectors: print(f"Undetectable: locations {config.location_indices}") ``` +```output +D0 flipped by X_0 at H([0]) +D0 flipped by Y_0 at H([0]) +D0 flipped by None at MZ([0]) +``` ## Tracked Operators From ff1839993c4075bf30857491a1edc299a8b03163 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 12:05:52 -0600 Subject: [PATCH 068/125] Refine operator taxonomy and tracked operator APIs --- crates/pecos-core/src/clifford.rs | 35 +- crates/pecos-core/src/clifford_rep.rs | 10 +- crates/pecos-core/src/gate_type.rs | 4 +- crates/pecos-core/src/lib.rs | 18 +- crates/pecos-core/src/op.rs | 332 +- crates/pecos-core/src/operator.rs | 4037 ----------------- crates/pecos-core/src/pauli.rs | 6 + crates/pecos-core/src/pauli/constructors.rs | 8 +- crates/pecos-core/src/unitary.rs | 29 + crates/pecos-core/src/unitary_rep.rs | 36 +- .../pecos-gpu-sims/src/gpu_noisy_sampler.rs | 185 +- crates/pecos-gpu-sims/src/lib.rs | 4 +- .../fault_tolerance/dem_builder/builder.rs | 14 +- .../fault_tolerance/dem_builder/sampler.rs | 22 +- .../src/fault_tolerance/dem_builder/types.rs | 26 +- .../src/fault_tolerance/fault_sampler.rs | 6 +- .../src/fault_tolerance/influence_builder.rs | 16 +- .../src/fault_tolerance/lookup_decoder.rs | 4 +- crates/pecos-qec/src/stabilizer_code.rs | 20 +- crates/pecos-qec/src/stabilizer_code_spec.rs | 54 +- .../tests/fault_enumeration_example.rs | 12 +- crates/pecos-qec/tests/targeted_tests.rs | 8 +- crates/pecos-quantum/examples/style_demo.rs | 2 +- crates/pecos-quantum/src/dag_circuit.rs | 34 +- crates/pecos-quantum/src/operator_matrix.rs | 1253 ----- crates/pecos-quantum/src/pauli_group.rs | 6 +- crates/pecos-quantum/src/pauli_sequence.rs | 16 +- crates/pecos-quantum/src/pauli_set.rs | 14 +- crates/pecos-quantum/src/stabilizer_group.rs | 14 +- crates/pecos-quantum/src/tick_circuit.rs | 36 +- crates/pecos-quantum/src/unitary_matrix.rs | 24 +- docs/development/foreign-plugins.md | 7 +- docs/user-guide/fault-catalog.md | 4 +- docs/user-guide/fault-tolerance.md | 19 +- docs/user-guide/gate-angle-types.md | 2 +- docs/user-guide/quantum-operator-algebra.md | 63 +- docs/user-guide/stabilizer-codes.md | 14 +- exp/pecos-eeg/src/builder.rs | 2 +- .../pecos-rslib-exp/src/sim_neo_bindings.rs | 12 +- .../pecos-rslib/src/dag_circuit_bindings.rs | 24 +- .../src/fault_tolerance_bindings.rs | 28 +- .../src/pecos/qec/surface/__init__.py | 4 +- .../src/pecos/qec/surface/circuit_builder.py | 97 +- python/quantum-pecos/tests/conftest.py | 43 +- python/quantum-pecos/tests/docs/conftest.py | 2 +- .../tests/docs/rust_crate/Cargo.lock | 16 + .../tests/docs/rust_crate/Cargo.toml | 1 + .../tests/development_foreign_plugins.rs | 13 - .../tests/user_guide_fault_tolerance.rs | 19 +- .../tests/user_guide_gate_angle_types.rs | 2 +- .../user_guide_quantum_operator_algebra.rs | 64 +- .../tests/user_guide_stabilizer_codes.rs | 26 +- .../tests/qec/test_dem_sampler.py | 8 +- .../tests/qec/test_fault_catalog.py | 2 +- scripts/docs/generate_doc_tests.py | 27 +- 55 files changed, 876 insertions(+), 5908 deletions(-) delete mode 100644 crates/pecos-core/src/operator.rs create mode 100644 crates/pecos-core/src/unitary.rs delete mode 100644 crates/pecos-quantum/src/operator_matrix.rs diff --git a/crates/pecos-core/src/clifford.rs b/crates/pecos-core/src/clifford.rs index cd767989e..a5817d756 100644 --- a/crates/pecos-core/src/clifford.rs +++ b/crates/pecos-core/src/clifford.rs @@ -10,36 +10,37 @@ // or implied. See the License for the specific language governing permissions and limitations under // the License. -//! Named Clifford gate primitives. +//! Clifford gate namespace. //! -//! The base Clifford gates (single-qubit and two-qubit), analogous to [`Pauli`] -//! for the Pauli group. The 24 single-qubit elements form a closed group with -//! fast composition via lookup. Two-qubit gates are the standard entangling primitives. -//! -//! # Example +//! This module provides the [`Clifford`] enum (named gate primitives) and +//! re-exports [`CliffordRep`] with free constructors for the Heisenberg-picture +//! representation. Use `use pecos_core::clifford::*` for Clifford-level work: //! //! ``` -//! use pecos_core::clifford::Clifford; -//! use pecos_core::Pauli; -//! use pecos_core::Sign; +//! use pecos_core::clifford::*; //! -//! let h = Clifford::H; -//! let (sign, p) = h.conjugate(Pauli::X); -//! assert_eq!(p, Pauli::Z); -//! assert_eq!(sign, Sign::PlusOne); +//! // Constructors return CliffordRep (composable Heisenberg-picture gates) +//! let layer = CX(0, 1) * H(0); //! -//! // Two-qubit gates -//! let cx_rep = Clifford::CX.on_qubits(0, 1); -//! assert!(cx_rep.is_valid()); +//! // The Clifford enum provides named gate primitives with Pauli conjugation +//! let h = Clifford::H; +//! let (sign, p) = h.conjugate(pecos_core::Pauli::X); +//! assert_eq!(p, pecos_core::Pauli::Z); //! ``` -use crate::clifford_rep::CliffordRep; use crate::gate_type::GateType; use crate::unitary_rep::UnitaryRep; use crate::{Angle64, Pauli, QubitId, Sign}; use std::fmt; use std::ops::Mul; +// Re-export CliffordRep and its constructors so `use pecos_core::clifford::*` works. +pub use crate::clifford_rep::CliffordRep; +pub use crate::clifford_rep::constructors::{ + CX, CY, CZ, F, F2, F2dg, F3, F3dg, F4, F4dg, Fdg, G, Gdg, H, H2, H3, H4, H5, H6, ISWAP, + ISWAPdg, Id, SWAP, SX, SXX, SXXdg, SXdg, SY, SYY, SYYdg, SYdg, SZ, SZZ, SZZdg, SZdg, +}; + /// Named Clifford gate primitive. /// /// Includes all 24 single-qubit Clifford gates and the standard two-qubit gates. diff --git a/crates/pecos-core/src/clifford_rep.rs b/crates/pecos-core/src/clifford_rep.rs index f65e428b7..ca7770684 100644 --- a/crates/pecos-core/src/clifford_rep.rs +++ b/crates/pecos-core/src/clifford_rep.rs @@ -19,7 +19,7 @@ //! //! ``` //! use pecos_core::clifford_rep::CliffordRep; -//! use pecos_core::unitary_rep::{X, Z}; +//! use pecos_core::unitary::{X, Z}; //! //! // Hadamard swaps X <-> Z //! let h = CliffordRep::h(0); @@ -186,7 +186,7 @@ impl CliffordRep { /// /// ``` /// use pecos_core::clifford_rep::CliffordRep; - /// use pecos_core::unitary_rep::{X, Z}; + /// use pecos_core::unitary::{X, Z}; /// /// let h = CliffordRep::h(0); /// let stabilizer = X(0) & Z(1); @@ -981,13 +981,13 @@ impl From<&PauliString> for CliffordRep { /// Free-standing constructor functions for Clifford gates. /// -/// These mirror the `pecos_core::pauli::constructors` module, providing -/// ergonomic gate creation and composition via the `*` operator. +/// These are re-exported through `pecos_core::clifford`, providing ergonomic +/// gate creation and composition via the `*` operator. /// /// # Examples /// /// ``` -/// use pecos_core::clifford_rep::constructors::*; +/// use pecos_core::clifford::*; /// /// // H * SZ * H = SX (sqrt-X) /// let sx = H(0) * SZ(0) * H(0); diff --git a/crates/pecos-core/src/gate_type.rs b/crates/pecos-core/src/gate_type.rs index 7a78555c6..65bdd992b 100644 --- a/crates/pecos-core/src/gate_type.rs +++ b/crates/pecos-core/src/gate_type.rs @@ -108,10 +108,10 @@ pub enum GateType { /// Free/deallocate a qubit QFree = 136, Idle = 200, - /// Meta-gate: Pauli operator annotation for fault tracking. + /// Meta-gate: tracked-operator annotation for fault tracking. /// /// This gate carries a Pauli string but has no effect on quantum state. - /// Its position in the circuit determines which faults can flip the operator + /// Its position in the circuit determines which faults can flip the tracked operator /// (only faults before this node are relevant). The propagator uses it as a /// backward propagation start point. /// diff --git a/crates/pecos-core/src/lib.rs b/crates/pecos-core/src/lib.rs index 59a86996c..32ab6d5b6 100644 --- a/crates/pecos-core/src/lib.rs +++ b/crates/pecos-core/src/lib.rs @@ -90,22 +90,28 @@ pub use circuit_diagram::{ DiagramStyleBuilder, FamilyPalette, FillPattern, GraphStyle, GraphStyleBuilder, blend_hex, }; -// UnitaryRep algebra +// --- Algebraic-level namespaces --- +// +// Each level is a module whose glob import gives the user the constructors and +// types for that algebraic level: +// +// use pecos_core::pauli::*; // I, X, Y, Z, Xs, Ys, Zs -> PauliString +// use pecos_core::clifford::*; // H, CX, CZ, SWAP, ... -> CliffordRep +// use pecos_core::unitary::*; // T, RZ, CCX, ... -> UnitaryRep +// use pecos_core::op::*; // MZ, PZ, Depolarizing, ... -> Op (promoted) + +pub mod unitary; pub use unitary_rep::{Is, Unitary, UnitaryRep}; -// PauliString constructors (primary user-facing API for Pauli algebra) pub use pauli::constructors::{I, X, Xs, Y, Ys, Z, Zs}; -// Clifford base type (single-qubit Clifford group element) pub mod clifford; pub use clifford::Clifford; -// Cross-type algebraic operators (Pauli * Clifford -> CliffordRep, etc.) pub mod gate_algebra; -// Unified gate algebra with automatic type promotion pub mod op; -pub use op::{Basis, ChannelExpr, Level, Op}; +pub use op::{Basis, ChannelExpr, GateExpr, Level, Op}; // Signals pub use signal::Signal; diff --git a/crates/pecos-core/src/op.rs b/crates/pecos-core/src/op.rs index 30a967c2e..8116dc197 100644 --- a/crates/pecos-core/src/op.rs +++ b/crates/pecos-core/src/op.rs @@ -12,20 +12,20 @@ //! Unified quantum operation algebra with automatic type promotion. //! -//! [`Op`] wraps four algebraic levels — [`PauliString`], [`CliffordRep`], -//! [`UnitaryRep`], and [`Channel`] — and automatically promotes to the +//! [`Op`] wraps five algebraic levels — [`PauliString`], [`CliffordRep`], +//! [`UnitaryRep`], [`GateExpr`], and [`ChannelExpr`] — and automatically promotes to the //! tightest level that can represent a combination. //! //! # Promotion Hierarchy //! //! ```text -//! Pauli ⊂ Clifford ⊂ Unitary ⊂ Channel +//! Pauli ⊂ Clifford ⊂ Unitary ⊂ Gate ⊂ Channel //! ``` //! //! Combining two `Op` values via tensor (`&`) or composition (`*`) promotes //! to the maximum level of the operands. The first three levels support full -//! algebraic operations including adjoint (`dg()`). The Channel level supports -//! tensor and composition but not adjoint. +//! algebraic operations including adjoint (`dg()`). The Gate and Channel levels +//! support tensor and composition but not adjoint. //! //! # Examples //! @@ -44,8 +44,12 @@ //! let u = X(0) & H(3) & T(5); //! assert!(u.is_unitary()); //! -//! // Adding a measurement promotes to Channel -//! let ch = H(0) & MZ(1); +//! // Adding a measurement promotes to Gate +//! let g = H(0) & MZ(1); +//! assert!(g.is_gate()); +//! +//! // Adding a noise channel promotes to Channel +//! let ch = g & Depolarizing(0.01, 2); //! assert!(ch.is_channel()); //! ``` @@ -61,7 +65,7 @@ pub use crate::unitary_rep::phase; /// Unified quantum operation with automatic level promotion. /// -/// Wraps one of four algebraic levels and promotes to the tightest +/// Wraps one of five algebraic levels and promotes to the tightest /// level when combined via `&` (tensor) or `*` (composition). /// /// The Clifford variant stores both a [`CliffordRep`] (for efficient Clifford @@ -74,7 +78,10 @@ pub enum Op { Clifford(CliffordRep, UnitaryRep), /// General unitary level: expression tree. Unitary(UnitaryRep), - /// Channel level: non-unitary quantum operations (measurements, preparations). + /// Gate level: ideal circuit operations such as unitary gates, preparation, + /// measurement, and reset. + Gate(GateExpr), + /// Channel level: general CPTP maps and noise/decoherence operations. Channel(ChannelExpr), } @@ -84,22 +91,43 @@ pub enum Level { Pauli = 0, Clifford = 1, Unitary = 2, - Channel = 3, + Gate = 3, + Channel = 4, } -/// A non-unitary quantum operation expression. +/// An ideal circuit operation expression. /// -/// Channels include measurements, preparations, noise channels (Kraus -/// operators), and their compositions. They compose and tensor like -/// unitaries but are not invertible. +/// Gate expressions represent operations that can appear in an ideal circuit +/// block: unitaries, preparations, measurements, resets, and their tensor or +/// sequential combinations. Measurement record allocation is owned by the +/// surrounding circuit representation, not by this expression. #[derive(Debug, Clone, PartialEq)] -pub enum ChannelExpr { +pub enum GateExpr { + /// A unitary operation lifted to the gate level. + Unitary(UnitaryRep), /// Prepare qubit in a given basis eigenstate. Prep { basis: Basis, qubit: usize }, - /// Measure qubit (produces classical bit). + /// Measure qubit in a given basis (produces a classical outcome). Measure { basis: Basis, qubit: usize }, + /// Reset qubit to the given basis eigenstate. + Reset { basis: Basis, qubit: usize }, + /// Tensor product of gate expressions. + Tensor(Vec), + /// Sequential composition: apply first element, then second, etc. + Compose(Vec), +} + +/// A general quantum channel expression. +/// +/// Channels include noise/decoherence maps, mixed unitaries, lifted ideal +/// gates, and their compositions. They compose and tensor like unitaries but +/// are not generally invertible. +#[derive(Debug, Clone, PartialEq)] +pub enum ChannelExpr { /// A unitary operation lifted to the channel level. Unitary(UnitaryRep), + /// An ideal gate expression lifted to the channel level. + Gate(GateExpr), /// Mixed-unitary channel: ρ → `Σ_k` `p_k` `U_k` ρ `U_k`†. /// /// Each entry is `(probability, unitary)` with probabilities summing to 1. @@ -121,10 +149,6 @@ pub enum ChannelExpr { /// replaced by the maximally mixed state and an erasure flag is raised. /// This is a heralded error — the location of the error is known. Erasure { prob: f64, qubit: usize }, - /// Reset channel: ρ → |0⟩⟨0| regardless of input state. - /// - /// Kraus operators: K₀ = |0⟩⟨0|, K₁ = |0⟩⟨1|. - Reset { qubit: usize }, /// Leakage channel: qubit transitions to a non-computational state /// with probability `rate`. /// @@ -165,6 +189,7 @@ impl Op { Op::Pauli(_) => Level::Pauli, Op::Clifford(..) => Level::Clifford, Op::Unitary(_) => Level::Unitary, + Op::Gate(_) => Level::Gate, Op::Channel(_) => Level::Channel, } } @@ -184,11 +209,25 @@ impl Op { matches!(self, Op::Unitary(_)) } + #[must_use] + pub fn is_gate(&self) -> bool { + matches!(self, Op::Gate(_)) + } + #[must_use] pub fn is_channel(&self) -> bool { matches!(self, Op::Channel(_)) } + /// Extracts the inner `GateExpr`, if at the Gate level. + #[must_use] + pub fn as_gate(&self) -> Option<&GateExpr> { + match self { + Op::Gate(gate) => Some(gate), + _ => None, + } + } + /// Extracts the inner `ChannelExpr`, if at the Channel level. #[must_use] pub fn as_channel(&self) -> Option<&ChannelExpr> { @@ -235,34 +274,48 @@ impl Op { } /// Consumes and returns the inner `CliffordRep`. - /// Pauli promotes to Clifford. Returns `None` for Unitary/Channel (cannot demote). + /// Pauli promotes to Clifford. Returns `None` for Unitary/Gate/Channel (cannot demote). #[must_use] pub fn into_clifford(self) -> Option { match self { Op::Pauli(ps) => Some(CliffordRep::from(ps)), Op::Clifford(cr, _) => Some(cr), - Op::Unitary(_) | Op::Channel(_) => None, + Op::Unitary(_) | Op::Gate(_) | Op::Channel(_) => None, } } /// Consumes and returns a `UnitaryRep`. - /// Returns `None` for Channel (cannot demote). + /// Returns `None` for Gate/Channel (cannot demote). #[must_use] pub fn into_unitary(self) -> Option { match self { Op::Pauli(ps) => Some(UnitaryRep::from(ps)), Op::Clifford(_, ur) | Op::Unitary(ur) => Some(ur), + Op::Gate(_) | Op::Channel(_) => None, + } + } + + /// Consumes and returns a `GateExpr`. Unitary and lower levels promote to + /// `GateExpr::Unitary`; Channel cannot demote. + #[must_use] + pub fn into_gate(self) -> Option { + match self { + Op::Pauli(ps) => Some(GateExpr::Unitary(UnitaryRep::from(ps))), + Op::Clifford(_, ur) | Op::Unitary(ur) => Some(GateExpr::Unitary(ur)), + Op::Gate(gate) => Some(gate), Op::Channel(_) => None, } } /// Consumes and returns a `ChannelExpr`. Always succeeds: - /// lower levels promote to `ChannelExpr::Unitary`. + /// unitary and lower levels promote to `ChannelExpr::Unitary`; Gate + /// promotes to `ChannelExpr::Gate`. #[must_use] pub fn into_channel(self) -> ChannelExpr { match self { Op::Pauli(ps) => ChannelExpr::Unitary(UnitaryRep::from(ps)), Op::Clifford(_, ur) | Op::Unitary(ur) => ChannelExpr::Unitary(ur), + Op::Gate(gate) => ChannelExpr::Gate(gate), Op::Channel(ch) => ch, } } @@ -280,16 +333,22 @@ impl Op { } /// Promotes this `Op` to at least the Unitary level. - /// Returns `None` if at Channel level (cannot demote). + /// Returns `None` if at Gate or Channel level (cannot demote). #[must_use] pub fn to_unitary_level(self) -> Option { match self { Op::Pauli(ps) => Some(Op::Unitary(UnitaryRep::from(ps))), Op::Clifford(_, ur) | Op::Unitary(ur) => Some(Op::Unitary(ur)), - Op::Channel(_) => None, + Op::Gate(_) | Op::Channel(_) => None, } } + /// Promotes this `Op` to the Gate level. + #[must_use] + pub fn to_gate_level(self) -> Option { + self.into_gate().map(Op::Gate) + } + /// Promotes this `Op` to the Channel level. #[must_use] pub fn to_channel_level(self) -> Op { @@ -299,25 +358,26 @@ impl Op { /// Returns the adjoint (dagger) of this expression. /// /// # Panics - /// Panics if called on a Channel-level `Op` (channels are not invertible). + /// Panics if called on a Gate-level or Channel-level `Op` (not generally invertible). #[must_use] pub fn dg(&self) -> Op { match self { Op::Pauli(ps) => Op::Pauli(ps.clone()), Op::Clifford(cr, ur) => cliff(cr.inverse(), ur.dg()), Op::Unitary(ur) => Op::Unitary(ur.dg()), + Op::Gate(_) => panic!("dg() is not defined for Gate-level operations"), Op::Channel(_) => panic!("dg() is not defined for Channel-level operations"), } } - /// Returns the adjoint if this is a unitary-level operation, `None` for channels. + /// Returns the adjoint if this is a unitary-level operation, `None` for gates/channels. #[must_use] pub fn try_dg(&self) -> Option { match self { Op::Pauli(ps) => Some(Op::Pauli(ps.clone())), Op::Clifford(cr, ur) => Some(cliff(cr.inverse(), ur.dg())), Op::Unitary(ur) => Some(Op::Unitary(ur.dg())), - Op::Channel(_) => None, + Op::Gate(_) | Op::Channel(_) => None, } } @@ -328,6 +388,7 @@ impl Op { Op::Pauli(ps) => ps.qubits(), Op::Clifford(cr, _) => (0..cr.num_qubits()).collect(), Op::Unitary(ur) => ur.qubits(), + Op::Gate(gate) => gate.qubits(), Op::Channel(ch) => ch.qubits(), } } @@ -339,6 +400,71 @@ impl Op { } } +// --- GateExpr methods --- + +impl GateExpr { + /// Returns the set of qubit indices this gate expression acts on. + #[must_use] + pub fn qubits(&self) -> Vec { + let mut qs = Vec::new(); + self.collect_qubits(&mut qs); + qs.sort_unstable(); + qs.dedup(); + qs + } + + fn collect_qubits(&self, out: &mut Vec) { + match self { + GateExpr::Prep { qubit, .. } + | GateExpr::Measure { qubit, .. } + | GateExpr::Reset { qubit, .. } => { + out.push(*qubit); + } + GateExpr::Unitary(ur) => { + out.extend(ur.qubits()); + } + GateExpr::Tensor(parts) | GateExpr::Compose(parts) => { + for part in parts { + part.collect_qubits(out); + } + } + } + } +} + +impl fmt::Display for GateExpr { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + GateExpr::Unitary(ur) => write!(f, "{ur:?}"), + GateExpr::Prep { basis, qubit } => write!(f, "P{basis:?}({qubit})"), + GateExpr::Measure { basis, qubit } => write!(f, "M{basis:?}({qubit})"), + GateExpr::Reset { + basis: Basis::Z, + qubit, + } => write!(f, "Reset({qubit})"), + GateExpr::Reset { basis, qubit } => write!(f, "Reset{basis:?}({qubit})"), + GateExpr::Tensor(parts) => { + for (i, part) in parts.iter().enumerate() { + if i > 0 { + write!(f, " & ")?; + } + write!(f, "{part}")?; + } + Ok(()) + } + GateExpr::Compose(parts) => { + for (i, part) in parts.iter().enumerate() { + if i > 0 { + write!(f, " * ")?; + } + write!(f, "{part}")?; + } + Ok(()) + } + } + } +} + // --- ChannelExpr methods --- impl ChannelExpr { @@ -354,18 +480,18 @@ impl ChannelExpr { fn collect_qubits(&self, out: &mut Vec) { match self { - ChannelExpr::Prep { qubit, .. } - | ChannelExpr::Measure { qubit, .. } - | ChannelExpr::AmplitudeDamping { qubit, .. } + ChannelExpr::AmplitudeDamping { qubit, .. } | ChannelExpr::PhaseDamping { qubit, .. } | ChannelExpr::Erasure { qubit, .. } - | ChannelExpr::Reset { qubit } | ChannelExpr::Leakage { qubit, .. } => { out.push(*qubit); } ChannelExpr::Unitary(ur) => { out.extend(ur.qubits()); } + ChannelExpr::Gate(gate) => { + out.extend(gate.qubits()); + } ChannelExpr::MixedUnitary(ops) => { for (_, ur) in ops { out.extend(ur.qubits()); @@ -383,9 +509,8 @@ impl ChannelExpr { impl fmt::Display for ChannelExpr { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { match self { - ChannelExpr::Prep { basis, qubit } => write!(f, "P{basis:?}({qubit})"), - ChannelExpr::Measure { basis, qubit } => write!(f, "M{basis:?}({qubit})"), ChannelExpr::Unitary(ur) => write!(f, "{ur:?}"), + ChannelExpr::Gate(gate) => write!(f, "{gate}"), ChannelExpr::MixedUnitary(ops) => { write!(f, "MixedUnitary[")?; for (i, (p, ur)) in ops.iter().enumerate() { @@ -405,7 +530,6 @@ impl fmt::Display for ChannelExpr { ChannelExpr::Erasure { prob, qubit } => { write!(f, "Erasure({prob}, {qubit})") } - ChannelExpr::Reset { qubit } => write!(f, "Reset({qubit})"), ChannelExpr::Leakage { rate, qubit } => { write!(f, "Leakage({rate}, {qubit})") } @@ -470,6 +594,11 @@ impl BitAnd for Op { let b = rhs.into_unitary().expect("max_level is Unitary"); Op::Unitary(a & b) } + Level::Gate => { + let a = self.into_gate().expect("max_level is Gate"); + let b = rhs.into_gate().expect("max_level is Gate"); + Op::Gate(GateExpr::Tensor(vec![a, b])) + } Level::Channel => { let a = self.into_channel(); let b = rhs.into_channel(); @@ -510,6 +639,11 @@ impl Mul for Op { let b = rhs.into_unitary().expect("max_level is Unitary"); Op::Unitary(a * b) } + Level::Gate => { + let a = self.into_gate().expect("max_level is Gate"); + let b = rhs.into_gate().expect("max_level is Gate"); + Op::Gate(GateExpr::Compose(vec![a, b])) + } Level::Channel => { let a = self.into_channel(); let b = rhs.into_channel(); @@ -573,6 +707,7 @@ impl Neg for Op { Op::Pauli(ps) => Op::Pauli(-ps), Op::Clifford(cr, ur) => cliff(cr, -ur), Op::Unitary(ur) => Op::Unitary(-ur), + Op::Gate(_) => panic!("negation is not defined for Gate-level operations"), Op::Channel(_) => panic!("negation is not defined for Channel-level operations"), } } @@ -594,6 +729,9 @@ impl Mul for ImaginaryUnit { Op::Pauli(ps) => Op::Pauli(self * ps), Op::Clifford(cr, ur) => cliff(cr, self * ur), Op::Unitary(ur) => Op::Unitary(self * ur), + Op::Gate(_) => { + panic!("phase multiplication is not defined for Gate-level operations") + } Op::Channel(_) => { panic!("phase multiplication is not defined for Channel-level operations") } @@ -617,6 +755,9 @@ impl Mul for NegImaginaryUnit { Op::Pauli(ps) => Op::Pauli(self * ps), Op::Clifford(cr, ur) => cliff(cr, self * ur), Op::Unitary(ur) => Op::Unitary(self * ur), + Op::Gate(_) => { + panic!("phase multiplication is not defined for Gate-level operations") + } Op::Channel(_) => { panic!("phase multiplication is not defined for Channel-level operations") } @@ -637,19 +778,22 @@ impl Mul<&Op> for NegImaginaryUnit { /// Applies the global phase e^{i*angle} to the operation. /// /// # Panics -/// Panics if applied to a Channel-level operation. +/// Panics if applied to a Gate-level or Channel-level operation. impl Mul for PhaseValue { type Output = Op; fn mul(self, rhs: Op) -> Op { match rhs { + Op::Gate(_) => { + panic!("phase multiplication is not defined for Gate-level operations") + } Op::Channel(_) => { panic!("phase multiplication is not defined for Channel-level operations") } other => { let ur = other .into_unitary() - .expect("non-Channel Op is convertible to Unitary"); + .expect("non-Gate/non-Channel Op is convertible to Unitary"); Op::Unitary(self * ur) } } @@ -702,6 +846,18 @@ impl From for Op { } } +impl From for Op { + fn from(gate: GateExpr) -> Op { + Op::Gate(gate) + } +} + +impl From for Op { + fn from(channel: ChannelExpr) -> Op { + Op::Channel(channel) + } +} + // --- Display --- impl fmt::Display for Op { @@ -710,6 +866,7 @@ impl fmt::Display for Op { Op::Pauli(ps) => write!(f, "{ps}"), Op::Clifford(cr, _) => write!(f, "{cr}"), Op::Unitary(ur) => write!(f, "{ur:?}"), + Op::Gate(gate) => write!(f, "{gate}"), Op::Channel(ch) => write!(f, "{ch}"), } } @@ -1179,13 +1336,13 @@ pub fn CCX(c0: impl Into, c1: impl Into, target: impl Into state (Z-basis preparation). #[allow(non_snake_case)] #[must_use] pub fn PZ(qubit: impl Into) -> Op { - Op::Channel(ChannelExpr::Prep { + Op::Gate(GateExpr::Prep { basis: Basis::Z, qubit: qubit.into().0, }) @@ -1195,7 +1352,7 @@ pub fn PZ(qubit: impl Into) -> Op { #[allow(non_snake_case)] #[must_use] pub fn PX(qubit: impl Into) -> Op { - Op::Channel(ChannelExpr::Prep { + Op::Gate(GateExpr::Prep { basis: Basis::X, qubit: qubit.into().0, }) @@ -1205,7 +1362,7 @@ pub fn PX(qubit: impl Into) -> Op { #[allow(non_snake_case)] #[must_use] pub fn MZ(qubit: impl Into) -> Op { - Op::Channel(ChannelExpr::Measure { + Op::Gate(GateExpr::Measure { basis: Basis::Z, qubit: qubit.into().0, }) @@ -1215,7 +1372,7 @@ pub fn MZ(qubit: impl Into) -> Op { #[allow(non_snake_case)] #[must_use] pub fn MX(qubit: impl Into) -> Op { - Op::Channel(ChannelExpr::Measure { + Op::Gate(GateExpr::Measure { basis: Basis::X, qubit: qubit.into().0, }) @@ -1405,7 +1562,8 @@ pub fn Erasure(prob: f64, qubit: impl Into) -> Op { #[allow(non_snake_case)] #[must_use] pub fn Reset(qubit: impl Into) -> Op { - Op::Channel(ChannelExpr::Reset { + Op::Gate(GateExpr::Reset { + basis: Basis::Z, qubit: qubit.into().0, }) } @@ -1589,8 +1747,9 @@ mod tests { } #[test] - fn into_unitary_none_for_channel() { + fn into_unitary_none_for_gate_and_channel() { assert!(MZ(0).into_unitary().is_none()); + assert!(Depolarizing(0.01, 0).into_unitary().is_none()); } // --- Level promotion --- @@ -1613,8 +1772,9 @@ mod tests { } #[test] - fn to_unitary_level_none_for_channel() { + fn to_unitary_level_none_for_gate_and_channel() { assert!(MZ(0).to_unitary_level().is_none()); + assert!(Depolarizing(0.01, 0).to_unitary_level().is_none()); } // --- Adjoint --- @@ -1763,6 +1923,8 @@ mod tests { fn level_ordering() { assert!(Level::Pauli < Level::Clifford); assert!(Level::Clifford < Level::Unitary); + assert!(Level::Unitary < Level::Gate); + assert!(Level::Gate < Level::Channel); } // --- From conversions --- @@ -1900,44 +2062,44 @@ mod tests { assert!(b.is_clifford()); } - // --- Channel level --- + // --- Gate level --- #[test] - fn channel_level() { - assert!(MZ(0).is_channel()); - assert!(MX(0).is_channel()); - assert!(PZ(0).is_channel()); - assert!(PX(0).is_channel()); + fn gate_level() { + assert!(MZ(0).is_gate()); + assert!(MX(0).is_gate()); + assert!(PZ(0).is_gate()); + assert!(PX(0).is_gate()); } #[test] - fn channel_tensor_stays_channel() { + fn gate_tensor_stays_gate() { let op = MZ(0) & MZ(1); - assert!(op.is_channel()); + assert!(op.is_gate()); } #[test] - fn channel_compose_stays_channel() { + fn gate_compose_stays_gate() { let op = PZ(0) * MZ(0); - assert!(op.is_channel()); + assert!(op.is_gate()); } #[test] - fn unitary_channel_tensor_promotes() { + fn unitary_gate_tensor_promotes() { let op = H(0) & MZ(1); - assert!(op.is_channel()); + assert!(op.is_gate()); } #[test] - fn pauli_channel_tensor_promotes() { + fn pauli_gate_tensor_promotes() { let op = X(0) & MZ(1); - assert!(op.is_channel()); + assert!(op.is_gate()); } #[test] - fn unitary_channel_compose_promotes() { + fn unitary_gate_compose_promotes() { let op = H(0) * MZ(0); - assert!(op.is_channel()); + assert!(op.is_gate()); } #[test] @@ -1950,12 +2112,21 @@ mod tests { } #[test] - fn into_clifford_none_for_channel() { + fn into_gate_promotes_unitaries_and_keeps_gates() { + assert!(X(0).into_gate().is_some()); + assert!(H(0).into_gate().is_some()); + assert!(T(0).into_gate().is_some()); + assert!(MZ(0).into_gate().is_some()); + assert!(Depolarizing(0.01, 0).into_gate().is_none()); + } + + #[test] + fn into_clifford_none_for_gate() { assert!(MZ(0).into_clifford().is_none()); } #[test] - fn try_dg_none_for_channel() { + fn try_dg_none_for_gate() { assert!(MZ(0).try_dg().is_none()); } @@ -1967,26 +2138,32 @@ mod tests { } #[test] - #[should_panic(expected = "not defined for Channel")] - fn dg_panics_for_channel() { + #[should_panic(expected = "not defined for Gate")] + fn dg_panics_for_gate() { let _ = MZ(0).dg(); } #[test] - fn channel_qubits() { + fn gate_qubits() { let op = MZ(3); assert_eq!(op.qubits(), vec![3]); assert_eq!(op.num_qubits(), 4); } #[test] - fn channel_tensor_qubits() { + fn gate_tensor_qubits() { let op = PZ(0) & MZ(2); let mut qs = op.qubits(); qs.sort_unstable(); assert_eq!(qs, vec![0, 2]); } + #[test] + fn gate_channel_tensor_promotes_to_channel() { + let op = MZ(0) & Depolarizing(0.01, 1); + assert!(op.is_channel()); + } + #[test] fn to_channel_level_promotes() { assert!(X(0).to_channel_level().is_channel()); @@ -1995,12 +2172,6 @@ mod tests { assert!(MZ(0).to_channel_level().is_channel()); } - #[test] - fn level_ordering_with_channel() { - assert!(Level::Unitary < Level::Channel); - assert!(Level::Pauli < Level::Channel); - } - // --- Noise channels --- #[test] @@ -2170,9 +2341,9 @@ mod tests { } #[test] - fn reset_is_channel() { + fn reset_is_gate() { let op = Reset(0); - assert!(op.is_channel()); + assert!(op.is_gate()); assert_eq!(op.qubits(), vec![0]); } @@ -2195,7 +2366,6 @@ mod tests { let ops = vec![ PhaseDamping(0.1, 0), Erasure(0.05, 0), - Reset(0), Leakage(0.01, 0), AmplitudeDamping(0.1, 0), ]; @@ -2333,25 +2503,25 @@ mod tests { #[test] #[should_panic(expected = "not defined for Channel")] fn i_times_channel_panics() { - let _ = i * MZ(0); + let _ = i * Depolarizing(0.01, 0); } #[test] #[should_panic(expected = "not defined for Channel")] fn neg_channel_panics() { - let _ = -MZ(0); + let _ = -Depolarizing(0.01, 0); } #[test] #[should_panic(expected = "not defined for Channel")] fn generic_phase_channel_panics() { - let _ = phase(Angle64::QUARTER_TURN) * MZ(0); + let _ = phase(Angle64::QUARTER_TURN) * Depolarizing(0.01, 0); } #[test] #[should_panic(expected = "negation is not defined for Channel")] fn minus_one_channel_panics() { - let _ = -1 * MZ(0); + let _ = -1 * Depolarizing(0.01, 0); } // --- Noise boundary values --- diff --git a/crates/pecos-core/src/operator.rs b/crates/pecos-core/src/operator.rs deleted file mode 100644 index aae35de9d..000000000 --- a/crates/pecos-core/src/operator.rs +++ /dev/null @@ -1,4037 +0,0 @@ -// Copyright 2024 The PECOS Developers -// -// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except -// in compliance with the License.You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software distributed under the License -// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express -// or implied. See the License for the specific language governing permissions and limitations under -// the License. - -//! Gate expression algebra for quantum circuits. -//! -//! This module provides a lazy expression tree for building and manipulating -//! quantum gate sequences with algebraic simplification. -//! -//! # Representation Hierarchy -//! -//! 1. **Rotation gates**: `exp(-i θ/2 P)` where P is a Pauli - covers most gates -//! 2. **Control gates**: CX, CZ, SWAP, etc. - stay as named gates -//! -//! # Operators -//! -//! - `&` - Tensor product (operators on different qubits) -//! - `*` - Composition (matrix multiplication order: A * B means apply B then A) -//! - `.dg()` - Adjoint (Hermitian conjugate) -//! -//! # Examples -//! -//! ``` -//! use pecos_core::operator::*; -//! use pecos_core::Angle64; -//! -//! // Build a circuit: H on q0, then CX(0,1), then T on q1 -//! let circuit = T(1) * CX(0, 1) * H(0); -//! -//! // Check if it's Clifford -//! assert!(!circuit.is_clifford()); // T is not Clifford -//! -//! // Clifford circuit -//! let cliff = CX(0, 1) * H(0); -//! assert!(cliff.is_clifford()); -//! -//! // Tensor product -//! let two_qubit = X(0) & Z(1); -//! -//! // Adjoint -//! let inv = circuit.dg(); -//! ``` - -use crate::gate_type::GateType; -use crate::pauli::PauliOperator; -use crate::phase::Phase; -use crate::{Angle64, PauliString, QuarterPhase, QubitId}; -use smallvec::SmallVec; -use std::ops::{BitAnd, Mul, Neg}; - -// --- Phase macros for exact arithmetic --- - -/// Creates a `PhaseValue` from a pi-based expression for use with operators. -/// -/// This is a convenience wrapper around `angle!` that returns a `PhaseValue` -/// which can be directly multiplied with gate expressions. -/// -/// # Examples -/// -/// ``` -/// use pecos_core::{phase, Angle64}; -/// use pecos_core::operator::X; -/// -/// // e^{iπ/4} * X - exact, no floating point -/// let op = phase!(pi / 4) * X(0); -/// -/// // e^{iπ/2} * X = i * X -/// let op = phase!(pi / 2) * X(0); -/// -/// // e^{i * 2π/3} * X -/// let op = phase!(2 * pi / 3) * X(0); -/// ``` -#[macro_export] -macro_rules! phase { - ($($tokens:tt)*) => { - $crate::operator::PhaseValue($crate::angle!($($tokens)*)) - }; -} - -/// Creates a `PhaseValue` from a turn-based fraction for use with operators. -/// -/// This is a convenience wrapper around `turn!` that returns a `PhaseValue` -/// which can be directly multiplied with gate expressions. -/// -/// # Examples -/// -/// ``` -/// use pecos_core::phase_turn; -/// use pecos_core::operator::X; -/// -/// // T gate phase: e^{i * 2π/8} = e^{iπ/4} -/// let op = phase_turn!(1 / 8) * X(0); -/// -/// // SZ gate phase: e^{i * 2π/4} = e^{iπ/2} = i -/// let op = phase_turn!(1 / 4) * X(0); -/// -/// // Third of a turn: e^{i * 2π/3} -/// let op = phase_turn!(1 / 3) * X(0); -/// ``` -#[macro_export] -macro_rules! phase_turn { - ($($tokens:tt)*) => { - $crate::operator::PhaseValue($crate::turn!($($tokens)*)) - }; -} - -/// Rotation gate types - gates parameterized by an angle. -#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] -pub enum RotationType { - /// Rotation around X axis: exp(-i θ/2 X) - RX, - /// Rotation around Y axis: exp(-i θ/2 Y) - RY, - /// Rotation around Z axis: exp(-i θ/2 Z) - RZ, - /// Two-qubit XX rotation: exp(-i θ/2 X⊗X) - RXX, - /// Two-qubit YY rotation: exp(-i θ/2 Y⊗Y) - RYY, - /// Two-qubit ZZ rotation: exp(-i θ/2 Z⊗Z) - RZZ, -} - -impl RotationType { - /// Returns the number of qubits this rotation acts on. - #[must_use] - pub fn num_qubits(&self) -> usize { - match self { - Self::RX | Self::RY | Self::RZ => 1, - Self::RXX | Self::RYY | Self::RZZ => 2, - } - } - - /// Returns the corresponding `GateType` for this rotation. - #[must_use] - pub fn to_gate_type(&self) -> GateType { - match self { - Self::RX => GateType::RX, - Self::RY => GateType::RY, - Self::RZ => GateType::RZ, - Self::RXX => GateType::RXX, - Self::RYY => GateType::RYY, - Self::RZZ => GateType::RZZ, - } - } -} - -// --- Commutativity --- - -/// Result of checking whether two operators commute. -#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] -pub enum Commutativity { - /// Operators commute: AB = BA - Commutes, - /// Operators anti-commute: AB = -BA - AntiCommutes, - /// Commutativity cannot be determined (non-Pauli operators) - Unknown, -} - -// --- Qubit target types for polymorphic gate constructors --- - -/// Wrapper for qubit targets that can be a single qubit or multiple qubits. -/// -/// Enables pluralized gate functions to accept various qubit collections: -/// ``` -/// use pecos_core::operator::*; -/// use pecos_core::QubitId; -/// -/// // Multiple qubits via Xs - equivalent to X(0) & X(2) & X(5) -/// let x_multi = Xs([0, 2, 5]); -/// -/// // Also works with QubitId arrays -/// let x_multi = Xs([QubitId(0), QubitId(2)]); -/// ``` -#[derive(Debug, Clone)] -pub struct Qubits(SmallVec<[QubitId; 4]>); - -impl From for Qubits { - fn from(q: usize) -> Self { - Qubits(smallvec::smallvec![QubitId(q)]) - } -} - -impl From for Qubits { - fn from(q: QubitId) -> Self { - Qubits(smallvec::smallvec![q]) - } -} - -impl From<[usize; N]> for Qubits { - fn from(qs: [usize; N]) -> Self { - Qubits(qs.into_iter().map(QubitId).collect()) - } -} - -impl From<[QubitId; N]> for Qubits { - fn from(qs: [QubitId; N]) -> Self { - Qubits(qs.into_iter().collect()) - } -} - -impl From<&[usize]> for Qubits { - fn from(qs: &[usize]) -> Self { - Qubits(qs.iter().copied().map(QubitId).collect()) - } -} - -impl From<&[QubitId]> for Qubits { - fn from(qs: &[QubitId]) -> Self { - Qubits(qs.iter().copied().collect()) - } -} - -impl From> for Qubits { - fn from(qs: Vec) -> Self { - Qubits(qs.into_iter().map(QubitId).collect()) - } -} - -impl From> for Qubits { - fn from(qs: Vec) -> Self { - Qubits(qs.into_iter().collect()) - } -} - -impl From> for Qubits { - fn from(range: std::ops::Range) -> Self { - assert!(!range.is_empty(), "empty range not allowed for Qubits"); - Qubits(range.map(QubitId).collect()) - } -} - -impl From> for Qubits { - fn from(range: std::ops::RangeInclusive) -> Self { - assert!(!range.is_empty(), "empty range not allowed for Qubits"); - Qubits(range.map(QubitId).collect()) - } -} - -impl Qubits { - /// Returns true if there are no qubits. - #[must_use] - pub fn is_empty(&self) -> bool { - self.0.is_empty() - } - - /// Returns the number of qubits. - #[must_use] - pub fn len(&self) -> usize { - self.0.len() - } - - /// Returns the qubits as a slice. - #[must_use] - pub fn as_slice(&self) -> &[QubitId] { - &self.0 - } - - /// Applies a gate function to each qubit and returns the result. - /// For a single qubit, returns the gate directly. - /// For multiple qubits, returns a Tensor of the gates. - #[must_use] - pub fn apply(self, gate_fn: F) -> Operator - where - F: Fn(usize) -> Operator, - { - match self.0.len() { - 0 => Operator::Pauli(PauliString::default()), // Identity - 1 => gate_fn(self.0[0].0), - _ => Operator::Tensor(self.0.iter().map(|q| gate_fn(q.0)).collect()), - } - } -} - -/// Wrapper for qubit pairs used by pluralized two-qubit gates. -/// -/// ``` -/// use pecos_core::operator::*; -/// use pecos_core::QubitId; -/// -/// // Multiple CX gates via CXs -/// let cx_multi = CXs([(0, 1), (2, 3)]); -/// -/// // Also works with QubitId pairs -/// let cx_multi = CXs([(QubitId(0), QubitId(1))]); -/// ``` -#[derive(Debug, Clone)] -pub struct QubitPairs(SmallVec<[(QubitId, QubitId); 2]>); - -impl From<(usize, usize)> for QubitPairs { - fn from(pair: (usize, usize)) -> Self { - QubitPairs(smallvec::smallvec![(QubitId(pair.0), QubitId(pair.1))]) - } -} - -impl From<(QubitId, QubitId)> for QubitPairs { - fn from(pair: (QubitId, QubitId)) -> Self { - QubitPairs(smallvec::smallvec![pair]) - } -} - -impl From<[(usize, usize); N]> for QubitPairs { - fn from(pairs: [(usize, usize); N]) -> Self { - QubitPairs( - pairs - .into_iter() - .map(|(a, b)| (QubitId(a), QubitId(b))) - .collect(), - ) - } -} - -impl From<[(QubitId, QubitId); N]> for QubitPairs { - fn from(pairs: [(QubitId, QubitId); N]) -> Self { - QubitPairs(pairs.into_iter().collect()) - } -} - -impl From<&[(usize, usize)]> for QubitPairs { - fn from(pairs: &[(usize, usize)]) -> Self { - QubitPairs( - pairs - .iter() - .map(|&(a, b)| (QubitId(a), QubitId(b))) - .collect(), - ) - } -} - -impl From<&[(QubitId, QubitId)]> for QubitPairs { - fn from(pairs: &[(QubitId, QubitId)]) -> Self { - QubitPairs(pairs.iter().copied().collect()) - } -} - -impl From> for QubitPairs { - fn from(pairs: Vec<(usize, usize)>) -> Self { - QubitPairs( - pairs - .into_iter() - .map(|(a, b)| (QubitId(a), QubitId(b))) - .collect(), - ) - } -} - -impl From> for QubitPairs { - fn from(pairs: Vec<(QubitId, QubitId)>) -> Self { - QubitPairs(pairs.into_iter().collect()) - } -} - -impl QubitPairs { - /// Returns true if there are no pairs. - #[must_use] - pub fn is_empty(&self) -> bool { - self.0.is_empty() - } - - /// Returns the number of pairs. - #[must_use] - pub fn len(&self) -> usize { - self.0.len() - } - - /// Applies a gate function to each pair and returns the result. - /// For a single pair, returns the gate directly. - /// For multiple pairs, returns a Tensor of the gates. - #[must_use] - pub fn apply(self, gate_fn: F) -> Operator - where - F: Fn(usize, usize) -> Operator, - { - match self.0.len() { - 0 => Operator::Pauli(PauliString::default()), // Identity - 1 => gate_fn(self.0[0].0.0, self.0[0].1.0), - _ => Operator::Tensor(self.0.iter().map(|(q0, q1)| gate_fn(q0.0, q1.0)).collect()), - } - } -} - -/// A gate/operator expression - lazy representation of quantum operators. -/// -/// This is the unified type for all quantum operators including Pauli operators, -/// Clifford gates, and general unitaries. -#[derive(Debug, Clone, PartialEq)] -pub enum Operator { - /// Pauli operator (single or multi-qubit) - /// Wraps `PauliString` for exact Pauli algebra - Pauli(PauliString), - - /// Rotation gate with angle: exp(-i θ/2 P) - Rotation { - rotation_type: RotationType, - angle: Angle64, - qubits: SmallVec<[usize; 2]>, - }, - - /// Fixed gate (control gates, etc.) without angle parameter - Gate { - gate_type: GateType, - qubits: SmallVec<[usize; 3]>, - }, - - /// Tensor product of expressions (operators on different qubits) - Tensor(Vec), - - /// Sequential composition (matrix multiplication order) - /// Compose([A, B, C]) means apply A, then B, then C - Compose(Vec), - - /// Adjoint (Hermitian conjugate) - Adjoint(Box), - - /// Global phase: e^{i*phase} * inner - /// Phase is represented as Angle64 for exact arithmetic - Phase { - phase: Angle64, - inner: Box, - }, -} - -impl Operator { - /// Creates a rotation gate expression. - #[must_use] - pub fn rotation( - rotation_type: RotationType, - angle: Angle64, - qubits: impl Into>, - ) -> Self { - Self::Rotation { - rotation_type, - angle, - qubits: qubits.into(), - } - } - - /// Creates a fixed gate expression. - #[must_use] - pub fn gate(gate_type: GateType, qubits: impl Into>) -> Self { - Self::Gate { - gate_type, - qubits: qubits.into(), - } - } - - /// Returns the adjoint (Hermitian conjugate) of this expression. - #[must_use] - pub fn dg(&self) -> Self { - match self { - // Pauli adjoint: Paulis are Hermitian, but phase conjugates - Self::Pauli(ps) => { - let conj_phase = ps.phase().conjugate(); - Self::Pauli(PauliString::with_phase_and_paulis( - conj_phase, - ps.iter_pairs().collect(), - )) - } - // Rotation adjoint: negate the angle - Self::Rotation { - rotation_type, - angle, - qubits, - } => Self::Rotation { - rotation_type: *rotation_type, - angle: negate_angle(*angle), - qubits: qubits.clone(), - }, - // Gate adjoint: wrap or simplify for self-adjoint gates - Self::Gate { - gate_type, - qubits: _, - } => { - if gate_type.is_self_adjoint() { - self.clone() - } else { - Self::Adjoint(Box::new(self.clone())) - } - } - // Tensor adjoint: adjoint of each part - Self::Tensor(parts) => Self::Tensor(parts.iter().map(Operator::dg).collect()), - // Compose adjoint: reverse order and adjoint each - Self::Compose(parts) => Self::Compose(parts.iter().rev().map(Operator::dg).collect()), - // Double adjoint: unwrap - Self::Adjoint(inner) => (**inner).clone(), - // Phase adjoint: conjugate phase (negate), adjoint inner - Self::Phase { phase, inner } => Self::Phase { - phase: negate_angle(*phase), - inner: Box::new(inner.dg()), - }, - } - } - - /// Applies a global phase to this expression: e^{i*phase} * self - #[must_use] - pub fn with_phase(self, phase: Angle64) -> Self { - if phase == Angle64::ZERO { - return self; - } - - // For Pauli variants, try to absorb the phase into the PauliString - // if it's a multiple of π/2 (quarter turn) - if let Self::Pauli(ps) = self { - if let Some(quarter_phase) = angle_to_quarter_phase(phase) { - let new_phase = ps.phase().multiply(&quarter_phase); - return Self::Pauli(PauliString::with_phase_and_paulis( - new_phase, - ps.iter_pairs().collect(), - )); - } - // Not a quarter turn multiple, wrap in Phase - return Self::Phase { - phase, - inner: Box::new(Self::Pauli(ps)), - }; - } - - Self::Phase { - phase, - inner: Box::new(self), - } - } - - /// Checks if this expression represents a Clifford operation. - /// - /// Clifford gates are those where all rotation angles are multiples of π/2. - #[must_use] - pub fn is_clifford(&self) -> bool { - match self { - // Paulis are always Clifford - Self::Pauli(_) => true, - Self::Rotation { angle, .. } => { - // Clifford if angle is multiple of π/2 (quarter turn) - is_multiple_of_quarter_turn(*angle) - } - Self::Gate { gate_type, .. } => gate_type.is_clifford(), - Self::Tensor(parts) | Self::Compose(parts) => parts.iter().all(Operator::is_clifford), - // Phase doesn't affect Clifford-ness (global phase) - Self::Adjoint(inner) | Self::Phase { inner, .. } => inner.is_clifford(), - } - } - - /// Returns the qubits this expression acts on. - #[must_use] - pub fn qubits(&self) -> Vec { - let mut result = Vec::new(); - self.collect_qubits(&mut result); - result.sort_unstable(); - result.dedup(); - result - } - - fn collect_qubits(&self, result: &mut Vec) { - match self { - Self::Pauli(ps) => { - result.extend(ps.iter_pairs().map(|(_, q)| usize::from(q))); - } - Self::Rotation { qubits, .. } => result.extend(qubits.iter().copied()), - Self::Gate { qubits, .. } => result.extend(qubits.iter().copied()), - Self::Tensor(parts) | Self::Compose(parts) => { - for part in parts { - part.collect_qubits(result); - } - } - Self::Adjoint(inner) | Self::Phase { inner, .. } => inner.collect_qubits(result), - } - } -} - -// --- Negation operator: -op (phase by π) --- - -impl Neg for Operator { - type Output = Operator; - - fn neg(self) -> Operator { - self.with_phase(Angle64::HALF_TURN) - } -} - -impl Neg for &Operator { - type Output = Operator; - - fn neg(self) -> Operator { - self.clone().with_phase(Angle64::HALF_TURN) - } -} - -// --- Imaginary unit for phase multiplication --- - -/// Imaginary unit for phase multiplication: i * op -#[derive(Debug, Clone, Copy, PartialEq, Eq)] -pub struct ImaginaryUnit; - -/// The imaginary unit `i`. -#[allow(non_upper_case_globals)] -pub const i: ImaginaryUnit = ImaginaryUnit; - -impl Neg for ImaginaryUnit { - type Output = NegImaginaryUnit; - - fn neg(self) -> NegImaginaryUnit { - NegImaginaryUnit - } -} - -/// Negative imaginary unit (-i). -#[derive(Debug, Clone, Copy, PartialEq, Eq)] -pub struct NegImaginaryUnit; - -impl Mul for ImaginaryUnit { - type Output = Operator; - - fn mul(self, rhs: Operator) -> Operator { - rhs.with_phase(Angle64::QUARTER_TURN) // i = e^{iπ/2} - } -} - -impl Mul<&Operator> for ImaginaryUnit { - type Output = Operator; - - fn mul(self, rhs: &Operator) -> Operator { - rhs.clone().with_phase(Angle64::QUARTER_TURN) - } -} - -impl Mul for NegImaginaryUnit { - type Output = Operator; - - #[allow(clippy::suspicious_arithmetic_impl)] // Adding angles for phase computation - fn mul(self, rhs: Operator) -> Operator { - rhs.with_phase(Angle64::QUARTER_TURN + Angle64::HALF_TURN) // -i = e^{i3π/2} - } -} - -impl Mul<&Operator> for NegImaginaryUnit { - type Output = Operator; - - #[allow(clippy::suspicious_arithmetic_impl)] // Adding angles for phase computation - fn mul(self, rhs: &Operator) -> Operator { - rhs.clone() - .with_phase(Angle64::QUARTER_TURN + Angle64::HALF_TURN) - } -} - -// --- General phase value for arbitrary phase multiplication --- - -/// A phase value e^{i*angle} that can be multiplied with operators. -/// -/// # Example -/// ``` -/// use pecos_core::operator::{phase, X}; -/// use pecos_core::Angle64; -/// -/// // Create a phase of e^{iπ/4} -/// let eighth_turn = Angle64::HALF_TURN / 4; -/// let op = phase(eighth_turn) * X(0); // e^{iπ/4} * X -/// ``` -#[derive(Debug, Clone, Copy, PartialEq)] -pub struct PhaseValue(pub Angle64); - -/// Creates a phase value e^{i*angle} that can be multiplied with operators. -/// -/// The phase represents the complex number e^{i*angle} = cos(angle) + i*sin(angle). -/// -/// # Example -/// ``` -/// use pecos_core::operator::{phase, X, Z}; -/// use pecos_core::Angle64; -/// -/// // e^{iπ/4} * X -/// let op = phase(Angle64::HALF_TURN / 4) * X(0); -/// -/// // e^{iπ/2} * Z = i * Z -/// let op = phase(Angle64::QUARTER_TURN) * Z(0); -/// ``` -#[must_use] -pub fn phase(angle: Angle64) -> PhaseValue { - PhaseValue(angle) -} - -impl Neg for PhaseValue { - type Output = PhaseValue; - - fn neg(self) -> PhaseValue { - // -e^{iθ} = e^{i(θ + π)} - PhaseValue(self.0 + Angle64::HALF_TURN) - } -} - -impl Mul for ImaginaryUnit { - type Output = PhaseValue; - - #[allow(clippy::suspicious_arithmetic_impl)] // Adding angles for phase computation - fn mul(self, rhs: PhaseValue) -> PhaseValue { - // i * e^{iθ} = e^{i(θ + π/2)} - PhaseValue(rhs.0 + Angle64::QUARTER_TURN) - } -} - -impl Mul for NegImaginaryUnit { - type Output = PhaseValue; - - #[allow(clippy::suspicious_arithmetic_impl)] // Adding angles for phase computation - fn mul(self, rhs: PhaseValue) -> PhaseValue { - // -i * e^{iθ} = e^{i(θ + 3π/2)} - PhaseValue(rhs.0 + Angle64::QUARTER_TURN + Angle64::HALF_TURN) - } -} - -impl Mul for PhaseValue { - type Output = Operator; - - fn mul(self, rhs: Operator) -> Operator { - rhs.with_phase(self.0) - } -} - -impl Mul<&Operator> for PhaseValue { - type Output = Operator; - - fn mul(self, rhs: &Operator) -> Operator { - rhs.clone().with_phase(self.0) - } -} - -impl Operator { - /// Attempts to convert a rotation to its named `GateType` equivalent. - #[must_use] - pub fn to_named_gate(&self) -> Option { - match self { - Self::Pauli(ps) => { - // Single-qubit Paulis map to named gates - if ps.weight() == 1 && ps.phase() == QuarterPhase::PlusOne { - let (pauli, _qubit) = ps.iter_pairs().next()?; - match pauli { - crate::Pauli::I => Some(GateType::I), - crate::Pauli::X => Some(GateType::X), - crate::Pauli::Y => Some(GateType::Y), - crate::Pauli::Z => Some(GateType::Z), - } - } else { - None - } - } - Self::Rotation { - rotation_type, - angle, - .. - } => rotation_to_gate_type(*rotation_type, *angle), - Self::Gate { gate_type, .. } => Some(*gate_type), - _ => None, - } - } - - /// Returns a reference to the inner `PauliString` if this is a `Pauli` variant. - #[must_use] - pub fn as_pauli_string(&self) -> Option<&PauliString> { - if let Self::Pauli(ps) = self { - Some(ps) - } else { - None - } - } - - /// Consumes this `Operator` and returns the inner `PauliString` if this is a `Pauli` variant. - #[must_use] - pub fn into_pauli_string(self) -> Option { - if let Self::Pauli(ps) = self { - Some(ps) - } else { - None - } - } - - /// Attempts to convert this operator to a `PauliString`. - /// - /// This handles more cases than `into_pauli_string()`: - /// - `Pauli(ps)` → returns `ps` directly - /// - `Tensor([Pauli(a), Pauli(b), ...])` → merges into a single `PauliString` - /// - `Phase { phase, inner: Pauli(ps) }` → applies phase to `ps` - /// - Named Pauli gates (`X`, `Y`, `Z`) → corresponding single-qubit `PauliString` - /// - Half-turn rotations (`RX(π)`, `RY(π)`, `RZ(π)`) → corresponding `PauliString` - /// - /// Returns `None` if the operator cannot be represented as a `PauliString`. - /// - /// # Example - /// - /// ``` - /// use pecos_core::{Xs, Zs, PauliOperator}; - /// - /// // Tensor of Paulis on disjoint qubits - /// let op = Xs(0..2) & Zs(2..4); - /// let ps = op.try_to_pauli_string().unwrap(); - /// assert_eq!(ps.weight(), 4); // X on 0,1 and Z on 2,3 - /// ``` - #[must_use] - pub fn try_to_pauli_string(self) -> Option { - match self { - Self::Pauli(ps) => Some(ps), - - Self::Tensor(parts) => { - // Try to convert all parts to PauliStrings and merge - let mut result = PauliString::new(); - for part in parts { - let ps = part.try_to_pauli_string()?; - // Merge: combine the Pauli operators - // For disjoint qubits, this is just concatenation - // For overlapping qubits, we multiply the Paulis - result = result * ps; - } - Some(result) - } - - Self::Phase { phase, inner } => { - let mut ps = inner.try_to_pauli_string()?; - // Apply the global phase to the PauliString phase - // phase is Angle64, we need to convert to QuarterPhase if possible - // For now, only handle quarter-turn phases exactly - let quarter_phase = if phase == Angle64::ZERO { - QuarterPhase::PlusOne - } else if phase == Angle64::QUARTER_TURN { - QuarterPhase::PlusI - } else if phase == Angle64::HALF_TURN { - QuarterPhase::MinusOne - } else if phase == Angle64::THREE_QUARTERS_TURN { - QuarterPhase::MinusI - } else { - // Non-quarter-turn phase, can't represent exactly - return None; - }; - let new_phase = ps.phase().multiply(&quarter_phase); - ps.set_phase(new_phase); - Some(ps) - } - - Self::Gate { gate_type, qubits } => { - let qubit = qubits.first().copied()?; - match gate_type { - GateType::X => Some(PauliString::x(qubit)), - GateType::Y => Some(PauliString::y(qubit)), - GateType::Z => Some(PauliString::z(qubit)), - GateType::I => Some(PauliString::identity()), - _ => None, - } - } - - Self::Rotation { - rotation_type, - angle, - qubits, - } => { - // Only half-turn rotations are Pauli operators - let half = Angle64::HALF_TURN; - let neg_half = negate_angle(half); - if angle != half && angle != neg_half { - return None; - } - let qubit = qubits.first().copied()?; - match rotation_type { - RotationType::RX => Some(PauliString::x(qubit)), - RotationType::RY => Some(PauliString::y(qubit)), - RotationType::RZ => Some(PauliString::z(qubit)), - _ => None, - } - } - - Self::Adjoint(inner) => { - // Paulis are Hermitian (self-adjoint), but phase conjugates - let mut ps = inner.try_to_pauli_string()?; - let conj_phase = ps.phase().conjugate(); - ps.set_phase(conj_phase); - Some(ps) - } - - Self::Compose(_) => { - // Composition of Paulis requires multiplication - // This is more complex; skip for now - None - } - } - } - - /// Checks if this operator is equivalent to a Pauli operator. - /// - /// Returns true for: - /// - `Pauli` variants (any `PauliString`) - /// - Half-turn rotations: `RX(π)`, `RY(π)`, `RZ(π)` - /// - Named Pauli gates: `X`, `Y`, `Z` - #[must_use] - pub fn is_pauli_equivalent(&self) -> bool { - match self { - Self::Pauli(_) => true, - Self::Rotation { - rotation_type, - angle, - .. - } => { - let half = Angle64::HALF_TURN; - let neg_half = negate_angle(half); - (*angle == half || *angle == neg_half) - && matches!( - rotation_type, - RotationType::RX | RotationType::RY | RotationType::RZ - ) - } - Self::Gate { gate_type, .. } => { - matches!(gate_type, GateType::X | GateType::Y | GateType::Z) - } - _ => false, - } - } - - /// Attempts to convert this operator to a `Pauli` variant. - /// - /// Converts: - /// - `Pauli` → returns as-is - /// - `RX(π)` → `X` - /// - `RY(π)` → `Y` - /// - `RZ(π)` → `Z` - /// - Named gates `X`, `Y`, `Z` → corresponding `Pauli` variant - /// - /// Returns `None` if the operator is not Pauli-equivalent. - #[must_use] - pub fn try_to_pauli(self) -> Option { - match self { - Self::Pauli(_) => Some(self), - Self::Rotation { - rotation_type, - angle, - qubits, - } => { - let half = Angle64::HALF_TURN; - let neg_half = negate_angle(half); - if angle != half && angle != neg_half { - return None; - } - let qubit = qubits[0]; - match rotation_type { - RotationType::RX => Some(X(qubit)), - RotationType::RY => Some(Y(qubit)), - RotationType::RZ => Some(Z(qubit)), - _ => None, - } - } - Self::Gate { gate_type, qubits } => { - let qubit = qubits[0]; - match gate_type { - GateType::X => Some(X(qubit)), - GateType::Y => Some(Y(qubit)), - GateType::Z => Some(Z(qubit)), - _ => None, - } - } - _ => None, - } - } - - /// Simplifies this gate expression by: - /// - Merging adjacent rotations of the same type on the same qubits - /// - Canceling inverse operations (rotation + its negation) - /// - Removing identity operations (zero-angle rotations) - /// - Flattening single-element containers - #[must_use] - #[allow(clippy::missing_panics_doc)] // Internal expects are guarded by length checks - pub fn simplify(&self) -> Self { - match self { - // Pauli and Gate are already in simplified form - Self::Pauli(_) | Self::Gate { .. } => self.clone(), - - Self::Rotation { angle, .. } => { - // Remove identity rotations - if *angle == Angle64::ZERO { - return self.clone(); // Keep as-is, will be filtered at Compose level - } - self.clone() - } - - Self::Tensor(parts) => { - // Simplify each part but preserve identities (they define the Hilbert space dimension) - let simplified: Vec<_> = parts.iter().map(Operator::simplify).collect(); - - match simplified.len() { - 0 => Self::Pauli(PauliString::default()), // Empty tensor = identity - 1 => simplified.into_iter().next().expect("length is 1"), - _ => Self::Tensor(simplified), - } - } - - Self::Compose(parts) => { - // First simplify each part - let simplified: Vec<_> = parts.iter().map(Operator::simplify).collect(); - - // Flatten nested Compose nodes - let flattened = flatten_compose(simplified); - - // Merge adjacent compatible rotations - let merged = merge_adjacent_rotations(flattened); - - // Filter out identities - let filtered: Vec<_> = merged.into_iter().filter(|p| !p.is_identity()).collect(); - - match filtered.len() { - 0 => I(0), // Empty composition = identity - 1 => filtered.into_iter().next().expect("length is 1"), - _ => Self::Compose(filtered), - } - } - - Self::Adjoint(inner) => { - // Simplify inner first, then take adjoint - let simplified_inner = inner.simplify(); - simplified_inner.dg() - } - - Self::Phase { phase, inner } => { - // Simplify inner and preserve phase - let simplified_inner = inner.simplify(); - if *phase == Angle64::ZERO || *phase == Angle64::FULL_TURN { - simplified_inner - } else { - Self::Phase { - phase: *phase, - inner: Box::new(simplified_inner), - } - } - } - } - } - - /// Conjugates this operator by another: `gate * self * gate.dg()` (i.e., UAU†). - /// - /// This is the stabilizer update convention: when gate U is applied to a state, - /// a stabilizer S transforms as S → U S U†. - /// - /// For Heisenberg picture evolution (U†AU), use [`conjdg`](Self::conjdg). - /// - /// # Example - /// - /// ``` - /// use pecos_core::operator::{X, Z, H, T}; - /// - /// // Stabilizer update: applying H to qubit 0 - /// let stabilizer = X(0) & Z(1); - /// let updated = stabilizer.conj(&H(0)); // H * (X⊗Z) * H† - /// - /// // Works with any operators - /// let a = T(0); - /// let b = X(0); - /// let conjugated = b.conj(&a); // T X T† - /// ``` - #[must_use] - pub fn conj(&self, gate: &Operator) -> Self { - gate.clone() * self.clone() * gate.dg() - } - - /// Conjugates this operator by the adjoint of another: `gate.dg() * self * gate` (i.e., U†AU). - /// - /// This is the Heisenberg picture convention: operators evolve as A → U†AU. - /// - /// For stabilizer updates (UAU†), use [`conj`](Self::conj). - /// - /// # Example - /// - /// ``` - /// use pecos_core::operator::{X, H}; - /// - /// // Heisenberg evolution: how X evolves under H - /// let evolved = X(0).conjdg(&H(0)); // H† X H - /// ``` - #[must_use] - pub fn conjdg(&self, gate: &Operator) -> Self { - gate.dg() * self.clone() * gate.clone() - } - - /// Returns the global phase of this operator. - /// - /// # Example - /// - /// ``` - /// use pecos_core::operator::{X, Y}; - /// use pecos_core::{GlobalPhase, QuarterPhase}; - /// - /// let op = X(0); - /// assert_eq!(op.phase(), GlobalPhase::one()); - /// - /// let op = -Y(0); - /// assert_eq!(op.phase(), GlobalPhase::minus_one()); - /// ``` - #[must_use] - pub fn phase(&self) -> crate::GlobalPhase { - use crate::GlobalPhase; - - match self { - Self::Pauli(ps) => GlobalPhase::from(ps.phase()), - Self::Phase { phase, .. } => GlobalPhase::from(*phase), - _ => GlobalPhase::one(), - } - } - - /// Returns the weight (number of qubits) this operator acts on. - /// - /// # Example - /// - /// ``` - /// use pecos_core::operator::{X, Z, CX}; - /// - /// assert_eq!(X(0).weight(), 1); - /// assert_eq!((X(0) & Z(2)).weight(), 2); - /// assert_eq!(CX(0, 1).weight(), 2); - /// ``` - #[must_use] - pub fn weight(&self) -> usize { - self.qubits().len() - } - - /// Checks if this is structurally the identity operator. - /// - /// # Example - /// - /// ``` - /// use pecos_core::operator::I; - /// - /// assert!(I(0).is_identity()); - /// ``` - #[must_use] - pub fn is_identity(&self) -> bool { - match self { - Self::Pauli(ps) => ps.weight() == 0 && ps.phase() == crate::QuarterPhase::PlusOne, - Self::Gate { gate_type, .. } => *gate_type == GateType::I, - Self::Rotation { angle, .. } => *angle == Angle64::ZERO, - Self::Tensor(parts) | Self::Compose(parts) => parts.iter().all(Operator::is_identity), - Self::Adjoint(inner) => inner.is_identity(), - Self::Phase { phase, inner } => *phase == Angle64::ZERO && inner.is_identity(), - } - } - - /// Checks if this operator is Hermitian (self-adjoint): A = A†. - /// - /// # Example - /// - /// ``` - /// use pecos_core::operator::{X, Y, Z, H, T}; - /// - /// // Paulis are Hermitian - /// assert!(X(0).is_hermitian()); - /// assert!(Y(0).is_hermitian()); - /// assert!(Z(0).is_hermitian()); - /// - /// // H is Hermitian - /// assert!(H(0).is_hermitian()); - /// - /// // T is not Hermitian (T† ≠ T) - /// assert!(!T(0).is_hermitian()); - /// ``` - #[must_use] - pub fn is_hermitian(&self) -> bool { - // A is Hermitian if A = A† - // For structural comparison, we check known Hermitian operators - match self { - Self::Pauli(_) => true, // All Paulis are Hermitian - Self::Gate { gate_type, .. } => matches!( - gate_type, - GateType::I - | GateType::X - | GateType::Y - | GateType::Z - | GateType::H - | GateType::CX - | GateType::CY - | GateType::CZ - | GateType::SWAP - ), - Self::Rotation { angle, .. } => { - // Rotations are Hermitian only at angle 0 or π - *angle == Angle64::ZERO || *angle == Angle64::HALF_TURN - } - Self::Tensor(parts) => parts.iter().all(Operator::is_hermitian), - // Composition of Hermitians isn't generally Hermitian; phase factors break Hermiticity - Self::Compose(_) | Self::Phase { .. } => false, - Self::Adjoint(inner) => inner.is_hermitian(), // (A†)† = A, so same as inner - } - } - - /// Returns the operator raised to a power (repeated composition). - /// - /// # Example - /// - /// ``` - /// use pecos_core::operator::{X, H}; - /// - /// let x = X(0); - /// let x2 = x.pow(2); // X * X = I - /// - /// let h = H(0); - /// let h3 = h.pow(3); // H * H * H = H - /// ``` - #[must_use] - pub fn pow(&self, n: u32) -> Self { - match n { - 0 => Self::Gate { - gate_type: GateType::I, - qubits: self - .qubits() - .into_iter() - .next() - .map_or(smallvec::smallvec![0], |q| smallvec::smallvec![q]), - }, - 1 => self.clone(), - _ => { - let mut result = self.clone(); - for _ in 1..n { - result = result * self.clone(); - } - result - } - } - } - - /// Checks whether this operator commutes with another. - /// - /// For Pauli operators, returns `Commutes` or `AntiCommutes`. - /// For non-Pauli operators, returns `Unknown`. - /// - /// # Example - /// - /// ``` - /// use pecos_core::operator::{X, Z, Commutativity}; - /// - /// let a = X(0); - /// let b = Z(0); - /// assert_eq!(a.commutes(&b), Commutativity::AntiCommutes); - /// - /// let c = X(0) & Z(1); - /// let d = Z(0) & X(1); - /// assert_eq!(c.commutes(&d), Commutativity::Commutes); - /// ``` - #[must_use] - pub fn commutes(&self, other: &Operator) -> Commutativity { - use crate::PauliOperator; - - match (self, other) { - (Self::Pauli(a), Self::Pauli(b)) => { - if a.commutes_with(b) { - Commutativity::Commutes - } else { - Commutativity::AntiCommutes - } - } - _ => Commutativity::Unknown, - } - } - - /// Returns whether this operator is unitary. - /// - /// All operators in this enum are unitary by construction. - /// - /// # Example - /// - /// ``` - /// use pecos_core::operator::{X, H, RZ}; - /// use pecos_core::Angle64; - /// - /// assert!(X(0).is_unitary()); - /// assert!(H(0).is_unitary()); - /// assert!(RZ(Angle64::QUARTER_TURN, 0).is_unitary()); - /// ``` - #[must_use] - pub fn is_unitary(&self) -> bool { - true // All Operator variants are unitary by construction - } - - /// Decomposes this operator into a sequence of primitive gates. - /// - /// Returns a flat vector of `Gate` structs representing the operator - /// as a sequence of native gates. - /// - /// # Example - /// - /// ``` - /// use pecos_core::operator::{H, CX}; - /// - /// let circuit = CX(0, 1) * H(0); // H then CX - /// let gates = circuit.decompose(); - /// assert_eq!(gates.len(), 2); - /// ``` - #[must_use] - pub fn decompose(&self) -> Vec { - use crate::{Gate, Pauli}; - - match self { - Self::Pauli(ps) => { - // Convert PauliString to individual gates - let mut gates = Vec::new(); - for (pauli, qubit) in ps.iter_pairs() { - let gate = match pauli { - Pauli::I => continue, // Skip identity - Pauli::X => Gate::simple(GateType::X, smallvec::smallvec![qubit]), - Pauli::Y => Gate::simple(GateType::Y, smallvec::smallvec![qubit]), - Pauli::Z => Gate::simple(GateType::Z, smallvec::smallvec![qubit]), - }; - gates.push(gate); - } - // Handle global phase if not +1 - // (Phase is tracked separately in PauliString but not representable in Gate) - gates - } - - Self::Rotation { - rotation_type, - angle, - qubits, - } => { - let gate_type = match rotation_type { - RotationType::RX => GateType::RX, - RotationType::RY => GateType::RY, - RotationType::RZ => GateType::RZ, - RotationType::RXX => GateType::RXX, - RotationType::RYY => GateType::RYY, - RotationType::RZZ => GateType::RZZ, - }; - let qubit_ids: crate::GateQubits = - qubits.iter().map(|&q| crate::QubitId(q)).collect(); - vec![Gate::with_angles( - gate_type, - smallvec::smallvec![*angle], - qubit_ids, - )] - } - - Self::Gate { gate_type, qubits } => { - let qubit_ids: crate::GateQubits = - qubits.iter().map(|&q| crate::QubitId(q)).collect(); - vec![Gate::simple(*gate_type, qubit_ids)] - } - - Self::Tensor(parts) => { - // Decompose each part and concatenate - parts.iter().flat_map(Operator::decompose).collect() - } - - Self::Compose(parts) => { - // Decompose each part in application order - parts.iter().flat_map(Operator::decompose).collect() - } - - Self::Adjoint(inner) => { - // Decompose inner, reverse, and adjoint each gate - let mut gates = inner.decompose(); - gates.reverse(); - for gate in &mut gates { - // Negate angles for rotation gates - for angle in &mut gate.angles { - *angle = Angle64::ZERO - *angle; - } - // Some gates need special handling - gate.gate_type = match gate.gate_type { - GateType::SX => GateType::SXdg, - GateType::SXdg => GateType::SX, - GateType::SY => GateType::SYdg, - GateType::SYdg => GateType::SY, - GateType::SZ => GateType::SZdg, - GateType::SZdg => GateType::SZ, - GateType::T => GateType::Tdg, - GateType::Tdg => GateType::T, - GateType::SZZ => GateType::SZZdg, - GateType::SZZdg => GateType::SZZ, - other => other, // Self-adjoint gates unchanged - }; - } - gates - } - - Self::Phase { inner, .. } => { - // Global phase doesn't affect gate sequence - // (Phase information is lost in decomposition) - inner.decompose() - } - } - } - - /// Converts this gate expression to a `CliffordRep` (generator propagation). - /// - /// Returns `None` if the expression contains non-Clifford operations. - /// - /// # Arguments - /// * `num_qubits` - The total number of qubits in the system - #[must_use] - pub fn to_clifford_rep(&self, num_qubits: usize) -> Option { - use crate::clifford_rep::CliffordRep; - - if !self.is_clifford() { - return None; - } - - match self { - Self::Pauli(ps) => { - // Convert PauliString to CliffordRep by composing single-qubit Paulis - let mut result = CliffordRep::identity(num_qubits); - for (pauli, qubit) in ps.iter_pairs() { - let q = usize::from(qubit); - let cliff = match pauli { - crate::Pauli::I => continue, // Skip identity - crate::Pauli::X => CliffordRep::x_on(q, num_qubits), - crate::Pauli::Y => CliffordRep::y_on(q, num_qubits), - crate::Pauli::Z => CliffordRep::z_on(q, num_qubits), - }; - result = cliff.compose(&result); - } - Some(result) - } - - Self::Rotation { - rotation_type, - angle, - qubits, - } => rotation_to_clifford_rep(*rotation_type, *angle, qubits, num_qubits), - - Self::Gate { gate_type, qubits } => { - gate_type_to_clifford_rep(*gate_type, qubits, num_qubits) - } - - Self::Tensor(parts) => { - // For tensor products, compose all parts (they act on different qubits) - let mut result = CliffordRep::identity(num_qubits); - for part in parts { - if let Some(cliff) = part.to_clifford_rep(num_qubits) { - result = result.compose(&cliff); - } else { - return None; - } - } - Some(result) - } - - Self::Compose(parts) => { - // For composition, compose in order (parts are in application order) - let mut result = CliffordRep::identity(num_qubits); - for part in parts { - if let Some(cliff) = part.to_clifford_rep(num_qubits) { - result = cliff.compose(&result); - } else { - return None; - } - } - Some(result) - } - - Self::Adjoint(inner) => { - // Get the inner CliffordRep and take its inverse - inner - .to_clifford_rep(num_qubits) - .map(|cliff| cliff.inverse()) - } - - Self::Phase { inner, .. } => { - // Global phase is ignored in CliffordRep (Heisenberg picture) - inner.to_clifford_rep(num_qubits) - } - } - } -} - -/// Convert a rotation to `CliffordRep` if it's Clifford. -fn rotation_to_clifford_rep( - rotation_type: RotationType, - angle: Angle64, - qubits: &SmallVec<[usize; 2]>, - num_qubits: usize, -) -> Option { - use crate::clifford_rep::CliffordRep; - - // Check for Clifford angles (multiples of π/2) - let quarter = Angle64::QUARTER_TURN; - let neg_quarter = negate_angle(quarter); - let half = Angle64::HALF_TURN; - let neg_half = negate_angle(half); - let three_quarter = quarter + half; - let _neg_three_quarter = negate_angle(three_quarter); - - // Identity - if angle == Angle64::ZERO { - return Some(CliffordRep::identity(num_qubits)); - } - - match rotation_type { - RotationType::RZ => { - let qubit = qubits[0]; - let mut result = CliffordRep::identity(num_qubits); - - if angle == quarter { - // S = RZ(π/2) - result = apply_s(&result, qubit); - } else if angle == neg_quarter || angle == three_quarter { - // S† = RZ(-π/2) = RZ(3π/2) - result = apply_sdg(&result, qubit); - } else if angle == half || angle == neg_half { - // Z = RZ(π) - result = apply_z(&result, qubit); - } else { - return None; // Not a Clifford angle - } - Some(result) - } - - RotationType::RX => { - let qubit = qubits[0]; - let mut result = CliffordRep::identity(num_qubits); - - if angle == quarter { - // SX = RX(π/2) - result = apply_sx(&result, qubit); - } else if angle == neg_quarter || angle == three_quarter { - // SX† = RX(-π/2) - result = apply_sxdg(&result, qubit); - } else if angle == half || angle == neg_half { - // X = RX(π) - result = apply_x(&result, qubit); - } else { - return None; - } - Some(result) - } - - RotationType::RY => { - let qubit = qubits[0]; - let mut result = CliffordRep::identity(num_qubits); - - if angle == quarter { - // SY = RY(π/2) - result = apply_sy(&result, qubit); - } else if angle == neg_quarter || angle == three_quarter { - // SY† = RY(-π/2) - result = apply_sydg(&result, qubit); - } else if angle == half || angle == neg_half { - // Y = RY(π) - result = apply_y(&result, qubit); - } else { - return None; - } - Some(result) - } - - RotationType::RZZ => { - let q0 = qubits[0]; - let q1 = qubits[1]; - - if angle == quarter { - Some(CliffordRep::cz(q0, q1).compose(&CliffordRep::identity(num_qubits))) - } else if angle == neg_quarter || angle == three_quarter { - // SZZ† - CZ with phase adjustment - Some(CliffordRep::cz(q0, q1).compose(&CliffordRep::identity(num_qubits))) - } else { - None - } - } - - _ => None, // RXX, RYY at non-zero angles are not standard Cliffords - } -} - -/// Convert a `GateType` to `CliffordRep`. -fn gate_type_to_clifford_rep( - gate_type: GateType, - qubits: &SmallVec<[usize; 3]>, - num_qubits: usize, -) -> Option { - use crate::clifford_rep::CliffordRep; - - match gate_type { - GateType::I => Some(CliffordRep::identity(num_qubits)), - GateType::X => { - let mut result = CliffordRep::identity(num_qubits); - result = apply_x(&result, qubits[0]); - Some(result) - } - GateType::Y => { - let mut result = CliffordRep::identity(num_qubits); - result = apply_y(&result, qubits[0]); - Some(result) - } - GateType::Z => { - let mut result = CliffordRep::identity(num_qubits); - result = apply_z(&result, qubits[0]); - Some(result) - } - GateType::H => { - let cliff = CliffordRep::h(qubits[0]); - // Extend to num_qubits - Some(extend_clifford(cliff, num_qubits)) - } - GateType::SX => { - let mut result = CliffordRep::identity(num_qubits); - result = apply_sx(&result, qubits[0]); - Some(result) - } - GateType::SY => { - let mut result = CliffordRep::identity(num_qubits); - result = apply_sy(&result, qubits[0]); - Some(result) - } - GateType::SZ => { - let mut result = CliffordRep::identity(num_qubits); - result = apply_s(&result, qubits[0]); - Some(result) - } - GateType::SXdg => { - let mut result = CliffordRep::identity(num_qubits); - result = apply_sxdg(&result, qubits[0]); - Some(result) - } - GateType::SYdg => { - let mut result = CliffordRep::identity(num_qubits); - result = apply_sydg(&result, qubits[0]); - Some(result) - } - GateType::SZdg => { - let mut result = CliffordRep::identity(num_qubits); - result = apply_sdg(&result, qubits[0]); - Some(result) - } - GateType::CX => { - let cliff = CliffordRep::cx(qubits[0], qubits[1]); - Some(extend_clifford(cliff, num_qubits)) - } - GateType::CY => { - let cliff = CliffordRep::cy(qubits[0], qubits[1]); - Some(extend_clifford(cliff, num_qubits)) - } - GateType::CZ => { - let cliff = CliffordRep::cz(qubits[0], qubits[1]); - Some(extend_clifford(cliff, num_qubits)) - } - GateType::SWAP => { - let cliff = CliffordRep::swap(qubits[0], qubits[1]); - Some(extend_clifford(cliff, num_qubits)) - } - _ => None, // Non-Clifford or unsupported gate - } -} - -/// Extend a `CliffordRep` to act on more qubits (identity on new qubits). -fn extend_clifford( - cliff: crate::clifford_rep::CliffordRep, - target_qubits: usize, -) -> crate::clifford_rep::CliffordRep { - use crate::clifford_rep::CliffordRep; - - if cliff.num_qubits() >= target_qubits { - return cliff; - } - - // Create a new CliffordRep with more qubits, copying the original images - // and using identity for the additional qubits - let mut result = CliffordRep::identity(target_qubits); - - // Copy the generator images from the original - for q in 0..cliff.num_qubits() { - result.set_x_image(q, cliff.x_image(q).clone()); - result.set_z_image(q, cliff.z_image(q).clone()); - } - // Additional qubits remain as identity (already set by CliffordRep::identity) - - result -} - -// Helper functions to apply single-qubit Cliffords to a CliffordRep -fn apply_x( - cliff: &crate::clifford_rep::CliffordRep, - qubit: usize, -) -> crate::clifford_rep::CliffordRep { - let x_cliff = crate::clifford_rep::CliffordRep::x(qubit); - extend_clifford(x_cliff, cliff.num_qubits()).compose(cliff) -} - -fn apply_y( - cliff: &crate::clifford_rep::CliffordRep, - qubit: usize, -) -> crate::clifford_rep::CliffordRep { - let y_cliff = crate::clifford_rep::CliffordRep::y(qubit); - extend_clifford(y_cliff, cliff.num_qubits()).compose(cliff) -} - -fn apply_z( - cliff: &crate::clifford_rep::CliffordRep, - qubit: usize, -) -> crate::clifford_rep::CliffordRep { - let z_cliff = crate::clifford_rep::CliffordRep::z(qubit); - extend_clifford(z_cliff, cliff.num_qubits()).compose(cliff) -} - -fn apply_s( - cliff: &crate::clifford_rep::CliffordRep, - qubit: usize, -) -> crate::clifford_rep::CliffordRep { - let s_cliff = crate::clifford_rep::CliffordRep::s(qubit); - extend_clifford(s_cliff, cliff.num_qubits()).compose(cliff) -} - -fn apply_sdg( - cliff: &crate::clifford_rep::CliffordRep, - qubit: usize, -) -> crate::clifford_rep::CliffordRep { - let sdg_cliff = crate::clifford_rep::CliffordRep::sdg(qubit); - extend_clifford(sdg_cliff, cliff.num_qubits()).compose(cliff) -} - -fn apply_sx( - cliff: &crate::clifford_rep::CliffordRep, - qubit: usize, -) -> crate::clifford_rep::CliffordRep { - let sx_cliff = crate::clifford_rep::CliffordRep::sx(qubit); - extend_clifford(sx_cliff, cliff.num_qubits()).compose(cliff) -} - -fn apply_sxdg( - cliff: &crate::clifford_rep::CliffordRep, - qubit: usize, -) -> crate::clifford_rep::CliffordRep { - // SX† = SX^3 = SX * SX * SX - let sx_cliff = crate::clifford_rep::CliffordRep::sx(qubit); - let extended = extend_clifford(sx_cliff.clone(), cliff.num_qubits()); - extended - .compose(&extended) - .compose(&extended) - .compose(cliff) -} - -fn apply_sy( - cliff: &crate::clifford_rep::CliffordRep, - qubit: usize, -) -> crate::clifford_rep::CliffordRep { - let sy_cliff = crate::clifford_rep::CliffordRep::sy(qubit); - extend_clifford(sy_cliff, cliff.num_qubits()).compose(cliff) -} - -fn apply_sydg( - cliff: &crate::clifford_rep::CliffordRep, - qubit: usize, -) -> crate::clifford_rep::CliffordRep { - // SY† = SY^3 - let sy_cliff = crate::clifford_rep::CliffordRep::sy(qubit); - let extended = extend_clifford(sy_cliff.clone(), cliff.num_qubits()); - extended - .compose(&extended) - .compose(&extended) - .compose(cliff) -} - -/// Flatten nested Compose nodes into a single level. -fn flatten_compose(parts: Vec) -> Vec { - let mut result = Vec::new(); - for part in parts { - match part { - Operator::Compose(inner_parts) => { - result.extend(flatten_compose(inner_parts)); - } - other => result.push(other), - } - } - result -} - -/// Merge adjacent rotations of the same type on the same qubits. -fn merge_adjacent_rotations(parts: Vec) -> Vec { - if parts.len() < 2 { - return parts; - } - - let mut result = Vec::with_capacity(parts.len()); - let mut idx = 0; - - while idx < parts.len() { - let current = &parts[idx]; - - // Check if next element can be merged with current - if idx + 1 < parts.len() - && let Some(merged) = try_merge_rotations(current, &parts[idx + 1]) - { - // Skip the merged element - if merged.is_identity() { - // Both cancelled out, skip both - idx += 2; - continue; - } - result.push(merged); - idx += 2; - continue; - } - - result.push(parts[idx].clone()); - idx += 1; - } - - // Recurse if we made any merges (might enable more merges) - if result.len() < parts.len() { - merge_adjacent_rotations(result) - } else { - result - } -} - -/// Try to merge two rotations if they are compatible. -/// Returns None if they cannot be merged. -fn try_merge_rotations(a: &Operator, b: &Operator) -> Option { - match (a, b) { - ( - Operator::Rotation { - rotation_type: rt_a, - angle: angle_a, - qubits: qubits_a, - }, - Operator::Rotation { - rotation_type: rt_b, - angle: angle_b, - qubits: qubits_b, - }, - ) => { - // Can only merge if same rotation type and same qubits - if rt_a == rt_b && qubits_a == qubits_b { - let combined_angle = *angle_a + *angle_b; - Some(Operator::Rotation { - rotation_type: *rt_a, - angle: combined_angle, - qubits: qubits_a.clone(), - }) - } else { - None - } - } - _ => None, - } -} - -/// Convert a rotation (type + angle) to a named `GateType` if one exists. -#[must_use] -pub fn rotation_to_gate_type(rotation_type: RotationType, angle: Angle64) -> Option { - // Check for standard angles - let quarter = Angle64::QUARTER_TURN; - let neg_quarter = negate_angle(quarter); - let half = Angle64::HALF_TURN; - let eighth = half / 4; // π/4 - let neg_eighth = negate_angle(eighth); - - match rotation_type { - RotationType::RZ => { - if angle == quarter { - Some(GateType::SZ) - } else if angle == neg_quarter { - Some(GateType::SZdg) - } else if angle == half { - Some(GateType::Z) - } else if angle == eighth { - Some(GateType::T) - } else if angle == neg_eighth { - Some(GateType::Tdg) - } else { - None - } - } - RotationType::RX => { - if angle == quarter { - Some(GateType::SX) - } else if angle == neg_quarter { - Some(GateType::SXdg) - } else if angle == half { - Some(GateType::X) - } else { - None - } - } - RotationType::RY => { - if angle == quarter { - Some(GateType::SY) - } else if angle == neg_quarter { - Some(GateType::SYdg) - } else if angle == half { - Some(GateType::Y) - } else { - None - } - } - RotationType::RZZ => { - if angle == quarter { - Some(GateType::SZZ) - } else if angle == neg_quarter { - Some(GateType::SZZdg) - } else { - None - } - } - _ => None, - } -} - -// --- Gate type helpers --- - -trait GateTypeExt { - fn is_clifford(&self) -> bool; - fn is_self_adjoint(&self) -> bool; -} - -impl GateTypeExt for GateType { - fn is_clifford(&self) -> bool { - use GateType::{CX, CY, CZ, H, I, SWAP, SX, SXdg, SY, SYdg, SZ, SZZ, SZZdg, SZdg, X, Y, Z}; - matches!( - self, - I | X - | Y - | Z - | H - | SX - | SXdg - | SY - | SYdg - | SZ - | SZdg - | CX - | CY - | CZ - | SWAP - | SZZ - | SZZdg - ) - } - - fn is_self_adjoint(&self) -> bool { - use GateType::{CX, CY, CZ, H, I, SWAP, X, Y, Z}; - matches!(self, I | X | Y | Z | H | CX | CY | CZ | SWAP) - } -} - -// --- Angle64 helpers --- - -/// Check if an angle is a multiple of a quarter turn (π/2). -/// -/// This is used to determine if a rotation is a Clifford gate. -fn is_multiple_of_quarter_turn(angle: Angle64) -> bool { - let quarter_fraction = Angle64::QUARTER_TURN.fraction(); - if quarter_fraction == 0 { - return true; // Edge case: if quarter is 0, everything is a multiple - } - angle.fraction().is_multiple_of(quarter_fraction) -} - -/// Negate an angle (for adjoint operations). -fn negate_angle(angle: Angle64) -> Angle64 { - Angle64::ZERO - angle -} - -/// Convert an angle to a `QuarterPhase` if it's a multiple of π/2. -/// -/// Returns None if the angle is not a multiple of π/2. -fn angle_to_quarter_phase(angle: Angle64) -> Option { - let quarter = Angle64::QUARTER_TURN; - let half = Angle64::HALF_TURN; - let three_quarters = quarter + half; - - if angle == Angle64::ZERO { - Some(QuarterPhase::PlusOne) - } else if angle == quarter { - Some(QuarterPhase::PlusI) - } else if angle == half { - Some(QuarterPhase::MinusOne) - } else if angle == three_quarters { - Some(QuarterPhase::MinusI) - } else { - None - } -} - -// --- Gate constructors - Single qubit rotations --- - -/// Rotation around X axis by the given angle. -/// -/// For multiple qubits, use `RXs(angle, [0, 1, 2])`. -#[must_use] -#[allow(non_snake_case)] -pub fn RX(angle: Angle64, qubit: impl Into) -> Operator { - Operator::rotation(RotationType::RX, angle, smallvec::smallvec![qubit.into().0]) -} - -/// RX rotations on multiple qubits. -/// -/// `RXs(angle, [0, 1, 2])` is equivalent to `RX(angle, 0) & RX(angle, 1) & RX(angle, 2)` -#[must_use] -#[allow(non_snake_case)] -pub fn RXs(angle: Angle64, qubits: impl Into) -> Operator { - qubits - .into() - .apply(|q| Operator::rotation(RotationType::RX, angle, smallvec::smallvec![q])) -} - -/// Rotation around Y axis by the given angle. -/// -/// For multiple qubits, use `RYs(angle, [0, 1, 2])`. -#[must_use] -#[allow(non_snake_case)] -pub fn RY(angle: Angle64, qubit: impl Into) -> Operator { - Operator::rotation(RotationType::RY, angle, smallvec::smallvec![qubit.into().0]) -} - -/// RY rotations on multiple qubits. -/// -/// `RYs(angle, [0, 1, 2])` is equivalent to `RY(angle, 0) & RY(angle, 1) & RY(angle, 2)` -#[must_use] -#[allow(non_snake_case)] -pub fn RYs(angle: Angle64, qubits: impl Into) -> Operator { - qubits - .into() - .apply(|q| Operator::rotation(RotationType::RY, angle, smallvec::smallvec![q])) -} - -/// Rotation around Z axis by the given angle. -/// -/// For multiple qubits, use `RZs(angle, [0, 1, 2])`. -#[must_use] -#[allow(non_snake_case)] -pub fn RZ(angle: Angle64, qubit: impl Into) -> Operator { - Operator::rotation(RotationType::RZ, angle, smallvec::smallvec![qubit.into().0]) -} - -/// RZ rotations on multiple qubits. -/// -/// `RZs(angle, [0, 1, 2])` is equivalent to `RZ(angle, 0) & RZ(angle, 1) & RZ(angle, 2)` -#[must_use] -#[allow(non_snake_case)] -pub fn RZs(angle: Angle64, qubits: impl Into) -> Operator { - qubits - .into() - .apply(|q| Operator::rotation(RotationType::RZ, angle, smallvec::smallvec![q])) -} - -// --- Gate constructors - Two qubit rotations --- - -/// Two-qubit XX rotation by the given angle. -/// -/// For multiple pairs, use `RXXs(angle, [(0, 1), (2, 3)])` or tensor. -#[must_use] -#[allow(non_snake_case)] -pub fn RXX(angle: Angle64, q0: impl Into, q1: impl Into) -> Operator { - Operator::rotation( - RotationType::RXX, - angle, - smallvec::smallvec![q0.into().0, q1.into().0], - ) -} - -/// RXX rotations on multiple qubit pairs. -/// -/// `RXXs(angle, [(0, 1), (2, 3)])` is equivalent to `RXX(angle, 0, 1) & RXX(angle, 2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn RXXs(angle: Angle64, pairs: impl Into) -> Operator { - pairs - .into() - .apply(|q0, q1| Operator::rotation(RotationType::RXX, angle, smallvec::smallvec![q0, q1])) -} - -/// Two-qubit YY rotation by the given angle. -/// -/// For multiple pairs, use `RYYs(angle, [(0, 1), (2, 3)])` or tensor. -#[must_use] -#[allow(non_snake_case)] -pub fn RYY(angle: Angle64, q0: impl Into, q1: impl Into) -> Operator { - Operator::rotation( - RotationType::RYY, - angle, - smallvec::smallvec![q0.into().0, q1.into().0], - ) -} - -/// RYY rotations on multiple qubit pairs. -/// -/// `RYYs(angle, [(0, 1), (2, 3)])` is equivalent to `RYY(angle, 0, 1) & RYY(angle, 2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn RYYs(angle: Angle64, pairs: impl Into) -> Operator { - pairs - .into() - .apply(|q0, q1| Operator::rotation(RotationType::RYY, angle, smallvec::smallvec![q0, q1])) -} - -/// Two-qubit ZZ rotation by the given angle. -/// -/// For multiple pairs, use `RZZs(angle, [(0, 1), (2, 3)])` or tensor. -#[must_use] -#[allow(non_snake_case)] -pub fn RZZ(angle: Angle64, q0: impl Into, q1: impl Into) -> Operator { - Operator::rotation( - RotationType::RZZ, - angle, - smallvec::smallvec![q0.into().0, q1.into().0], - ) -} - -/// RZZ rotations on multiple qubit pairs. -/// -/// `RZZs(angle, [(0, 1), (2, 3)])` is equivalent to `RZZ(angle, 0, 1) & RZZ(angle, 2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn RZZs(angle: Angle64, pairs: impl Into) -> Operator { - pairs - .into() - .apply(|q0, q1| Operator::rotation(RotationType::RZZ, angle, smallvec::smallvec![q0, q1])) -} - -// --- Gate constructors - Named single-qubit Cliffords --- - -/// Identity gate on a single qubit. -#[must_use] -#[allow(non_snake_case)] -pub fn I(qubit: impl Into) -> Operator { - RZ(Angle64::ZERO, qubit.into().0) -} - -/// Identity gates on multiple qubits. -#[must_use] -#[allow(non_snake_case)] -pub fn Is(qubits: impl Into) -> Operator { - qubits.into().apply(|q| RZ(Angle64::ZERO, q)) -} - -/// Pauli X operator on a single qubit. -/// -/// For multiple qubits, use `Xs([0, 2, 5])` or tensor: `X(0) & X(2) & X(5)` -#[must_use] -#[allow(non_snake_case)] -pub fn X(qubit: impl Into) -> Operator { - Operator::Pauli(PauliString::x(qubit.into().0)) -} - -/// Pauli X operators on multiple qubits. -/// -/// `Xs([0, 2, 5])` is equivalent to `X(0) & X(2) & X(5)` -#[must_use] -#[allow(non_snake_case)] -pub fn Xs(qubits: impl Into) -> Operator { - let qs = qubits.into(); - if qs.0.is_empty() { - Operator::Pauli(PauliString::default()) - } else { - let mut ps = PauliString::x(qs.0[0].0); - for q in &qs.0[1..] { - ps = ps & PauliString::x(q.0); - } - Operator::Pauli(ps) - } -} - -/// Pauli Y operator on a single qubit. -/// -/// For multiple qubits, use `Ys([0, 2, 5])` or tensor: `Y(0) & Y(2) & Y(5)` -#[must_use] -#[allow(non_snake_case)] -pub fn Y(qubit: impl Into) -> Operator { - Operator::Pauli(PauliString::y(qubit.into().0)) -} - -/// Pauli Y operators on multiple qubits. -/// -/// `Ys([0, 2, 5])` is equivalent to `Y(0) & Y(2) & Y(5)` -#[must_use] -#[allow(non_snake_case)] -pub fn Ys(qubits: impl Into) -> Operator { - let qs = qubits.into(); - if qs.0.is_empty() { - Operator::Pauli(PauliString::default()) - } else { - let mut ps = PauliString::y(qs.0[0].0); - for q in &qs.0[1..] { - ps = ps & PauliString::y(q.0); - } - Operator::Pauli(ps) - } -} - -/// Pauli Z operator on a single qubit. -/// -/// For multiple qubits, use `Zs([0, 2, 5])` or tensor: `Z(0) & Z(2) & Z(5)` -#[must_use] -#[allow(non_snake_case)] -pub fn Z(qubit: impl Into) -> Operator { - Operator::Pauli(PauliString::z(qubit.into().0)) -} - -/// Pauli Z operators on multiple qubits. -/// -/// `Zs([0, 2, 5])` is equivalent to `Z(0) & Z(2) & Z(5)` -#[must_use] -#[allow(non_snake_case)] -pub fn Zs(qubits: impl Into) -> Operator { - let qs = qubits.into(); - if qs.0.is_empty() { - Operator::Pauli(PauliString::default()) - } else { - let mut ps = PauliString::z(qs.0[0].0); - for q in &qs.0[1..] { - ps = ps & PauliString::z(q.0); - } - Operator::Pauli(ps) - } -} - -/// SX gate (sqrt X): RX(π/2) -#[must_use] -#[allow(non_snake_case)] -pub fn SX(qubit: impl Into) -> Operator { - RX(Angle64::QUARTER_TURN, qubit.into().0) -} - -/// SX gates on multiple qubits. -#[must_use] -#[allow(non_snake_case)] -pub fn SXs(qubits: impl Into) -> Operator { - qubits.into().apply(|q| RX(Angle64::QUARTER_TURN, q)) -} - -/// SY gate (sqrt Y): RY(π/2) -#[must_use] -#[allow(non_snake_case)] -pub fn SY(qubit: impl Into) -> Operator { - RY(Angle64::QUARTER_TURN, qubit.into().0) -} - -/// SY gates on multiple qubits. -#[must_use] -#[allow(non_snake_case)] -pub fn SYs(qubits: impl Into) -> Operator { - qubits.into().apply(|q| RY(Angle64::QUARTER_TURN, q)) -} - -/// SZ gate (sqrt Z): RZ(π/2) -#[must_use] -#[allow(non_snake_case)] -pub fn SZ(qubit: impl Into) -> Operator { - RZ(Angle64::QUARTER_TURN, qubit.into().0) -} - -/// SZ gates on multiple qubits. -#[must_use] -#[allow(non_snake_case)] -pub fn SZs(qubits: impl Into) -> Operator { - qubits.into().apply(|q| RZ(Angle64::QUARTER_TURN, q)) -} - -/// T gate: RZ(π/4) -#[must_use] -#[allow(non_snake_case)] -pub fn T(qubit: impl Into) -> Operator { - RZ(Angle64::HALF_TURN / 4, qubit.into().0) -} - -/// T gates on multiple qubits. -#[must_use] -#[allow(non_snake_case)] -pub fn Ts(qubits: impl Into) -> Operator { - qubits.into().apply(|q| RZ(Angle64::HALF_TURN / 4, q)) -} - -/// Hadamard gate: RZ(π) * RY(π/2) (up to global phase) -#[must_use] -#[allow(non_snake_case)] -pub fn H(qubit: impl Into) -> Operator { - let q = qubit.into().0; - Operator::Gate { - gate_type: GateType::H, - qubits: smallvec::smallvec![q], - } -} - -/// Hadamard gates on multiple qubits. -#[must_use] -#[allow(non_snake_case)] -pub fn Hs(qubits: impl Into) -> Operator { - qubits.into().apply(|q| { - Operator::Compose(vec![ - RZ(Angle64::HALF_TURN, q), - RY(Angle64::QUARTER_TURN, q), - ]) - }) -} - -// --- Gate constructors - Named two-qubit gates --- - -/// CNOT (CX) gate. -/// -/// For multiple pairs, use `CXs([(0, 1), (2, 3)])` or tensor: `CX(0, 1) & CX(2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn CX(control: impl Into, target: impl Into) -> Operator { - Operator::gate( - GateType::CX, - smallvec::smallvec![control.into().0, target.into().0], - ) -} - -/// CX gates on multiple qubit pairs. -/// -/// `CXs([(0, 1), (2, 3)])` is equivalent to `CX(0, 1) & CX(2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn CXs(pairs: impl Into) -> Operator { - pairs - .into() - .apply(|ctrl, tgt| Operator::gate(GateType::CX, smallvec::smallvec![ctrl, tgt])) -} - -/// Controlled-Y gate. -/// -/// For multiple pairs, use `CYs([(0, 1), (2, 3)])` or tensor: `CY(0, 1) & CY(2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn CY(control: impl Into, target: impl Into) -> Operator { - Operator::gate( - GateType::CY, - smallvec::smallvec![control.into().0, target.into().0], - ) -} - -/// CY gates on multiple qubit pairs. -/// -/// `CYs([(0, 1), (2, 3)])` is equivalent to `CY(0, 1) & CY(2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn CYs(pairs: impl Into) -> Operator { - pairs - .into() - .apply(|ctrl, tgt| Operator::gate(GateType::CY, smallvec::smallvec![ctrl, tgt])) -} - -/// Controlled-Z gate. -/// -/// For multiple pairs, use `CZs([(0, 1), (2, 3)])` or tensor: `CZ(0, 1) & CZ(2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn CZ(q0: impl Into, q1: impl Into) -> Operator { - Operator::gate(GateType::CZ, smallvec::smallvec![q0.into().0, q1.into().0]) -} - -/// CZ gates on multiple qubit pairs. -/// -/// `CZs([(0, 1), (2, 3)])` is equivalent to `CZ(0, 1) & CZ(2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn CZs(pairs: impl Into) -> Operator { - pairs - .into() - .apply(|q0, q1| Operator::gate(GateType::CZ, smallvec::smallvec![q0, q1])) -} - -/// SWAP gate. -/// -/// For multiple pairs, use `SWAPs([(0, 1), (2, 3)])` or tensor: `SWAP(0, 1) & SWAP(2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn SWAP(q0: impl Into, q1: impl Into) -> Operator { - Operator::gate( - GateType::SWAP, - smallvec::smallvec![q0.into().0, q1.into().0], - ) -} - -/// SWAP gates on multiple qubit pairs. -/// -/// `SWAPs([(0, 1), (2, 3)])` is equivalent to `SWAP(0, 1) & SWAP(2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn SWAPs(pairs: impl Into) -> Operator { - pairs - .into() - .apply(|q0, q1| Operator::gate(GateType::SWAP, smallvec::smallvec![q0, q1])) -} - -/// SZZ gate: RZZ(π/2) -/// -/// For multiple pairs, use `SZZs([(0, 1), (2, 3)])` or tensor: `SZZ(0, 1) & SZZ(2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn SZZ(q0: impl Into, q1: impl Into) -> Operator { - Operator::rotation( - RotationType::RZZ, - Angle64::QUARTER_TURN, - smallvec::smallvec![q0.into().0, q1.into().0], - ) -} - -/// SZZ gates on multiple qubit pairs. -/// -/// `SZZs([(0, 1), (2, 3)])` is equivalent to `SZZ(0, 1) & SZZ(2, 3)` -#[must_use] -#[allow(non_snake_case)] -pub fn SZZs(pairs: impl Into) -> Operator { - pairs.into().apply(|q0, q1| { - Operator::rotation( - RotationType::RZZ, - Angle64::QUARTER_TURN, - smallvec::smallvec![q0, q1], - ) - }) -} - -// --- Gate constructors - Three-qubit gates --- - -/// Toffoli (CCX) gate. -#[must_use] -#[allow(non_snake_case)] -pub fn CCX(c0: impl Into, c1: impl Into, target: impl Into) -> Operator { - Operator::gate( - GateType::CCX, - smallvec::smallvec![c0.into().0, c1.into().0, target.into().0], - ) -} - -// --- Operator implementations --- - -// Tensor product: & -impl BitAnd for Operator { - type Output = Operator; - - fn bitand(self, rhs: Operator) -> Operator { - match (self, rhs) { - // Pauli & Pauli: use PauliString tensor product - (Operator::Pauli(a), Operator::Pauli(b)) => Operator::Pauli(a & b), - // Flatten nested tensors - (Operator::Tensor(mut parts), Operator::Tensor(rhs_parts)) => { - parts.extend(rhs_parts); - Operator::Tensor(parts) - } - (Operator::Tensor(mut parts), rhs) => { - parts.push(rhs); - Operator::Tensor(parts) - } - (lhs, Operator::Tensor(mut parts)) => { - parts.insert(0, lhs); - Operator::Tensor(parts) - } - (lhs, rhs) => Operator::Tensor(vec![lhs, rhs]), - } - } -} - -// Composition: * -impl Mul for Operator { - type Output = Operator; - - fn mul(self, rhs: Operator) -> Operator { - // A * B means apply B first, then A (matrix multiplication order) - // So we store as [B, A] in the Compose vec (application order) - match (self, rhs) { - // Pauli * Pauli: use PauliString algebra - (Operator::Pauli(a), Operator::Pauli(b)) => Operator::Pauli(a * b), - // Flatten nested compositions - (Operator::Compose(lhs_parts), Operator::Compose(rhs_parts)) => { - // rhs applied first, then lhs - let mut result = rhs_parts; - result.extend(lhs_parts); - Operator::Compose(result) - } - (Operator::Compose(lhs_parts), rhs) => { - // rhs applied first - let mut result = vec![rhs]; - result.extend(lhs_parts); - Operator::Compose(result) - } - (lhs, Operator::Compose(mut rhs_parts)) => { - // rhs_parts applied first, then lhs - rhs_parts.push(lhs); - Operator::Compose(rhs_parts) - } - (lhs, rhs) => { - // rhs applied first, then lhs - Operator::Compose(vec![rhs, lhs]) - } - } - } -} - -// --- Circuit diagram generation --- - -impl Operator { - /// Generates an ASCII circuit diagram for this expression. - #[must_use] - pub fn to_diagram(&self, num_qubits: usize) -> String { - let mut diagram = CircuitDiagram::new(num_qubits); - self.add_to_diagram(&mut diagram); - diagram.render() - } - - fn add_to_diagram(&self, diagram: &mut CircuitDiagram) { - match self { - Self::Pauli(ps) => { - // Draw each Pauli on its qubit - for (pauli, qubit) in ps.iter_pairs() { - let q = usize::from(qubit); - let name = match pauli { - crate::Pauli::I => continue, - crate::Pauli::X => "X", - crate::Pauli::Y => "Y", - crate::Pauli::Z => "Z", - }; - diagram.add_single_gate(q, name); - } - } - Self::Rotation { - rotation_type, - angle, - qubits, - } => { - let name = if let Some(gate_type) = rotation_to_gate_type(*rotation_type, *angle) { - format!("{gate_type:?}") - } else { - format!("{rotation_type:?}") - }; - - if qubits.len() == 1 { - diagram.add_single_gate(qubits[0], &name); - } else if qubits.len() == 2 { - diagram.add_two_qubit_gate(qubits[0], qubits[1], &name); - } - } - Self::Gate { gate_type, qubits } => match gate_type { - GateType::CX => { - diagram.add_controlled_gate(qubits[0], qubits[1], "X"); - } - GateType::CY => { - diagram.add_controlled_gate(qubits[0], qubits[1], "Y"); - } - GateType::CZ => { - diagram.add_controlled_gate(qubits[0], qubits[1], "Z"); - } - GateType::SWAP => { - diagram.add_swap(qubits[0], qubits[1]); - } - GateType::CCX => { - diagram.add_toffoli(qubits[0], qubits[1], qubits[2]); - } - _ => { - if qubits.len() == 1 { - diagram.add_single_gate(qubits[0], &format!("{gate_type:?}")); - } - } - }, - Self::Tensor(parts) => { - // Tensor products can be drawn simultaneously - for part in parts { - part.add_to_diagram(diagram); - } - } - Self::Compose(parts) => { - // Sequential composition: draw in order - for part in parts { - part.add_to_diagram(diagram); - diagram.advance(); - } - } - Self::Adjoint(inner) => { - // Mark as adjoint somehow? - inner.add_to_diagram(diagram); - } - Self::Phase { inner, .. } => { - // Global phase doesn't appear in circuit diagrams - inner.add_to_diagram(diagram); - } - } - } -} - -struct CircuitDiagram { - num_qubits: usize, - columns: Vec>, - current_col: usize, -} - -impl CircuitDiagram { - fn new(num_qubits: usize) -> Self { - Self { - num_qubits, - columns: vec![vec![String::new(); num_qubits * 2 - 1]], - current_col: 0, - } - } - - fn ensure_column(&mut self) { - if self.current_col >= self.columns.len() { - self.columns - .push(vec![String::new(); self.num_qubits * 2 - 1]); - } - } - - fn advance(&mut self) { - self.current_col += 1; - } - - fn add_single_gate(&mut self, qubit: usize, name: &str) { - self.ensure_column(); - let row = qubit * 2; - if row < self.columns[self.current_col].len() { - self.columns[self.current_col][row] = format!("[{name}]"); - } - } - - fn add_controlled_gate(&mut self, control: usize, target: usize, target_name: &str) { - self.ensure_column(); - let ctrl_row = control * 2; - let targ_row = target * 2; - - if ctrl_row < self.columns[self.current_col].len() { - self.columns[self.current_col][ctrl_row] = "●".to_string(); - } - if targ_row < self.columns[self.current_col].len() { - self.columns[self.current_col][targ_row] = format!("[{target_name}]"); - } - - // Draw vertical line - let (min_row, max_row) = if ctrl_row < targ_row { - (ctrl_row, targ_row) - } else { - (targ_row, ctrl_row) - }; - for row in (min_row + 1)..max_row { - if row % 2 == 1 && self.columns[self.current_col][row].is_empty() { - self.columns[self.current_col][row] = "│".to_string(); - } - } - } - - fn add_swap(&mut self, q0: usize, q1: usize) { - self.ensure_column(); - let row0 = q0 * 2; - let row1 = q1 * 2; - - if row0 < self.columns[self.current_col].len() { - self.columns[self.current_col][row0] = "×".to_string(); - } - if row1 < self.columns[self.current_col].len() { - self.columns[self.current_col][row1] = "×".to_string(); - } - - // Draw vertical line - let (min_row, max_row) = (row0.min(row1), row0.max(row1)); - for row in (min_row + 1)..max_row { - if row % 2 == 1 && self.columns[self.current_col][row].is_empty() { - self.columns[self.current_col][row] = "│".to_string(); - } - } - } - - fn add_toffoli(&mut self, c0: usize, c1: usize, target: usize) { - self.ensure_column(); - let c0_row = c0 * 2; - let c1_row = c1 * 2; - let targ_row = target * 2; - - if c0_row < self.columns[self.current_col].len() { - self.columns[self.current_col][c0_row] = "●".to_string(); - } - if c1_row < self.columns[self.current_col].len() { - self.columns[self.current_col][c1_row] = "●".to_string(); - } - if targ_row < self.columns[self.current_col].len() { - self.columns[self.current_col][targ_row] = "[X]".to_string(); - } - - // Draw vertical lines - let min_row = c0_row.min(c1_row).min(targ_row); - let max_row = c0_row.max(c1_row).max(targ_row); - for row in (min_row + 1)..max_row { - if row % 2 == 1 && self.columns[self.current_col][row].is_empty() { - self.columns[self.current_col][row] = "│".to_string(); - } - } - } - - fn add_two_qubit_gate(&mut self, q0: usize, q1: usize, name: &str) { - self.ensure_column(); - let row0 = q0 * 2; - let row1 = q1 * 2; - - if row0 < self.columns[self.current_col].len() { - self.columns[self.current_col][row0] = format!("[{name}]"); - } - if row1 < self.columns[self.current_col].len() { - self.columns[self.current_col][row1] = format!("[{name}]"); - } - - // Draw vertical line - let (min_row, max_row) = (row0.min(row1), row0.max(row1)); - for row in (min_row + 1)..max_row { - if row % 2 == 1 && self.columns[self.current_col][row].is_empty() { - self.columns[self.current_col][row] = "│".to_string(); - } - } - } - - fn render(&self) -> String { - let lines: Vec = (0..self.num_qubits).map(|q| format!("q{q}: ")).collect(); - - // Add spacing lines between qubits - let mut all_lines: Vec = Vec::new(); - for (idx, line) in lines.iter().enumerate() { - all_lines.push(line.clone()); - if idx < self.num_qubits - 1 { - all_lines.push(" ".to_string()); // spacing line - } - } - - // Process each column - for col in &self.columns { - // Find max width in this column - let max_width = col - .iter() - .map(|s| s.chars().count()) - .max() - .unwrap_or(0) - .max(3); - - for (row, cell) in col.iter().enumerate() { - if row < all_lines.len() { - if cell.is_empty() { - // Wire or empty - if row % 2 == 0 { - all_lines[row].push_str(&"─".repeat(max_width)); - } else { - all_lines[row].push_str(&" ".repeat(max_width)); - } - } else { - // Center the cell content - let padding = max_width.saturating_sub(cell.chars().count()); - let left_pad = padding / 2; - let right_pad = padding - left_pad; - - if row % 2 == 0 { - // Qubit line - all_lines[row].push_str(&"─".repeat(left_pad)); - all_lines[row].push_str(cell); - all_lines[row].push_str(&"─".repeat(right_pad)); - } else { - // Spacing line - all_lines[row].push_str(&" ".repeat(left_pad)); - all_lines[row].push_str(cell); - all_lines[row].push_str(&" ".repeat(right_pad)); - } - } - } - } - } - - // Add trailing wire - for (idx, line) in all_lines.iter_mut().enumerate() { - if idx % 2 == 0 { - line.push('─'); - } - } - - all_lines.join("\n") - } -} - - -#[cfg(test)] -mod tests { - use super::*; - - #[test] - fn test_single_qubit_gates() { - let x = X(0); - let z = Z(1); - let h = H(0); - - assert!(x.is_clifford()); - assert!(z.is_clifford()); - assert!(h.is_clifford()); - } - - #[test] - fn test_t_gate_not_clifford() { - let t = T(0); - assert!(!t.is_clifford()); - } - - #[test] - fn test_tensor_product() { - let op = X(0) & Z(1); - assert!(op.is_clifford()); - - // Pauli & Pauli now produces a single Pauli variant - if let Operator::Pauli(ps) = &op { - assert_eq!(ps.get(0), crate::Pauli::X); - assert_eq!(ps.get(1), crate::Pauli::Z); - } else { - panic!("Expected Pauli, got {op:?}"); - } - - // Mixed tensor (Pauli with non-Pauli) produces Tensor - let mixed = X(0) & H(1); - assert!(matches!(mixed, Operator::Tensor(_))); - } - - #[test] - fn test_composition() { - let circuit = T(0) * H(0); - assert!(!circuit.is_clifford()); // T is not Clifford - - let cliff_circuit = SZ(0) * H(0); - assert!(cliff_circuit.is_clifford()); - } - - #[test] - fn test_control_gates() { - let cx = CX(0, 1); - let cz = CZ(0, 1); - - assert!(cx.is_clifford()); - assert!(cz.is_clifford()); - } - - #[test] - fn test_adjoint() { - let t = T(0); - let t_dg = t.dg(); - - // T† should have negated angle - if let Operator::Rotation { angle, .. } = t_dg { - let t_angle = Angle64::HALF_TURN / 4; - let expected = negate_angle(t_angle); - assert_eq!(angle, expected); - } else { - panic!("Expected Rotation"); - } - } - - #[test] - fn test_double_adjoint() { - let h = H(0); - let h_dg_dg = h.dg().dg(); - - // H†† should equal H (structurally) - assert_eq!(h, h_dg_dg); - } - - #[test] - fn test_qubits() { - let circuit = CX(0, 1) * H(0) * T(2); - let qubits = circuit.qubits(); - assert_eq!(qubits, vec![0, 1, 2]); - } - - #[test] - fn test_to_named_gate() { - let sz = SZ(0); - assert_eq!(sz.to_named_gate(), Some(GateType::SZ)); - - let t = T(0); - assert_eq!(t.to_named_gate(), Some(GateType::T)); - - let x = X(0); - assert_eq!(x.to_named_gate(), Some(GateType::X)); - } - - #[test] - fn test_diagram_single_qubit() { - let h = H(0); - let diagram = h.to_diagram(1); - assert!(diagram.contains("[H]")); - } - - #[test] - fn test_diagram_cx() { - let cx = CX(0, 1); - let diagram = cx.to_diagram(2); - assert!(diagram.contains("●")); - assert!(diagram.contains("[X]")); - } - - #[test] - fn test_diagram_complex() { - // Build a circuit: H(0), CX(0,1), T(1) - let circuit = T(1) * CX(0, 1) * H(0); - let diagram = circuit.to_diagram(2); - println!("Circuit diagram:\n{diagram}"); - - // Also test a 3-qubit circuit - let circuit3 = CCX(0, 1, 2) * H(0) * H(1); - let diagram3 = circuit3.to_diagram(3); - println!("\n3-qubit circuit:\n{diagram3}"); - } - - #[test] - fn test_composition_order() { - // A * B means apply B first, then A - // Test composition with rotations - let circuit = SZ(0) * SY(0) * SX(0); // Apply SX, then SY, then SZ - - if let Operator::Compose(parts) = circuit { - assert_eq!(parts.len(), 3); - // All should be rotations - assert!(matches!(&parts[0], Operator::Rotation { .. })); - assert!(matches!(&parts[1], Operator::Rotation { .. })); - assert!(matches!(&parts[2], Operator::Rotation { .. })); - } else { - panic!("Expected Compose"); - } - } - -// --- Simplify tests --- - - #[test] - fn test_simplify_identity() { - let id = I(0); - assert!(id.is_identity()); - } - - #[test] - fn test_simplify_cancellation() { - // T * T† should simplify to identity - let t = T(0); - let t_dg = t.dg(); - let circuit = t.clone() * t_dg; - let simplified = circuit.simplify(); - - // Should be identity (zero-angle rotation) - assert!(simplified.is_identity()); - } - - #[test] - fn test_simplify_merge_adjacent() { - // SZ * SZ = Z (RZ(π/2) + RZ(π/2) = RZ(π)) - let circuit = SZ(0) * SZ(0); - let simplified = circuit.simplify(); - - // Should merge into a single rotation - if let Operator::Rotation { - angle, - rotation_type, - .. - } = simplified - { - assert_eq!(rotation_type, RotationType::RZ); - assert_eq!(angle, Angle64::HALF_TURN); // π - } else { - panic!("Expected single Rotation, got {simplified:?}"); - } - } - - #[test] - fn test_simplify_preserves_different_qubits() { - // RZ on different qubits shouldn't merge - let circuit = RZ(Angle64::QUARTER_TURN, 0) * RZ(Angle64::QUARTER_TURN, 1); - let simplified = circuit.simplify(); - - // Should remain a Compose with 2 parts - if let Operator::Compose(parts) = simplified { - assert_eq!(parts.len(), 2); - } else { - panic!("Expected Compose"); - } - } - - #[test] - fn test_simplify_preserves_different_rotation_types() { - // RX and RZ on same qubit shouldn't merge - let circuit = RX(Angle64::QUARTER_TURN, 0) * RZ(Angle64::QUARTER_TURN, 0); - let simplified = circuit.simplify(); - - // Should remain a Compose with 2 parts - if let Operator::Compose(parts) = simplified { - assert_eq!(parts.len(), 2); - } else { - panic!("Expected Compose"); - } - } - - #[test] - fn test_simplify_multiple_merges() { - // T * T * T * T = Z (4 * π/4 = π) - let circuit = T(0) * T(0) * T(0) * T(0); - let simplified = circuit.simplify(); - - if let Operator::Rotation { angle, .. } = simplified { - assert_eq!(angle, Angle64::HALF_TURN); - } else { - panic!("Expected single Rotation"); - } - } - - #[test] - fn test_simplify_tensor_preserves_identity() { - // X(0) & I(1) should preserve the identity to maintain Hilbert space dimension - let circuit = X(0) & I(1); - let simplified = circuit.simplify(); - - // Should still be a tensor with both parts (preserves 2-qubit space) - let qubits = simplified.qubits(); - assert!(qubits.contains(&0)); - assert!(qubits.contains(&1)); - } - - #[test] - fn test_simplify_compose_with_gate() { - // CX doesn't merge with rotations - let circuit = SZ(0) * CX(0, 1) * SZ(0); - let simplified = circuit.simplify(); - - // Should have 3 parts (S, CX, S) - if let Operator::Compose(parts) = simplified { - assert_eq!(parts.len(), 3); - } else { - panic!("Expected Compose"); - } - } - -// --- CliffordRep conversion tests --- - - #[test] - fn test_to_clifford_rep_non_clifford_returns_none() { - let t = T(0); - assert!(t.to_clifford_rep(1).is_none()); - } - - #[test] - fn test_to_clifford_rep_identity() { - let id = I(0); - let cliff = id.to_clifford_rep(1).unwrap(); - - // Identity should transform X -> X, Z -> Z - let x0 = PauliString::x(0); - let z0 = PauliString::z(0); - - let tx = cliff.apply(&x0); - let tz = cliff.apply(&z0); - - assert_eq!(tx.get(0), crate::Pauli::X); - assert_eq!(tz.get(0), crate::Pauli::Z); - } - - #[test] - fn test_to_clifford_rep_x_gate() { - let x = X(0); - let cliff = x.to_clifford_rep(1).unwrap(); - - // X gate: X -> X, Z -> -Z - let z0 = PauliString::z(0); - - let tz = cliff.apply(&z0); - assert_eq!(tz.get(0), crate::Pauli::Z); - assert_eq!(tz.phase(), crate::QuarterPhase::MinusOne); - } - - #[test] - fn test_to_clifford_rep_s_gate() { - let s = SZ(0); - let cliff = s.to_clifford_rep(1).unwrap(); - - // SZ gate: X -> Y, Z -> Z - let x0 = PauliString::x(0); - - let tx = cliff.apply(&x0); - assert_eq!(tx.get(0), crate::Pauli::Y); - } - - #[test] - fn test_to_clifford_rep_cx_gate() { - let cx = CX(0, 1); - let cliff = cx.to_clifford_rep(2).unwrap(); - - // CX: X_control -> X_control * X_target - let x0 = PauliString::x(0); - - let tx = cliff.apply(&x0); - // Should have X on both qubits - assert_eq!(tx.get(0), crate::Pauli::X); - assert_eq!(tx.get(1), crate::Pauli::X); - } - - #[test] - fn test_to_clifford_rep_composition() { - // S * H should be convertible - let circuit = SZ(0) * H(0); - let cliff = circuit.to_clifford_rep(1); - assert!(cliff.is_some()); - } - -// --- Phase tests --- - - #[test] - fn test_phase_basic() { - // phase(π/4) * X should create a phased operator - // Since π/4 is not a quarter-turn multiple, it wraps in Phase - let eighth_turn = Angle64::HALF_TURN / 4; - let op = phase(eighth_turn) * X(0); - - if let Operator::Phase { phase: p, inner } = op { - assert_eq!(p, eighth_turn); - // Inner should be Pauli(X) - assert!(matches!(*inner, Operator::Pauli(_))); - } else { - panic!("Expected Phase variant, got {op:?}"); - } - } - - #[test] - fn test_phase_negation() { - // -phase(θ) = phase(θ + π) - let quarter = Angle64::QUARTER_TURN; - let p = phase(quarter); - let neg_p = -p; - - assert_eq!(neg_p.0, quarter + Angle64::HALF_TURN); - } - - #[test] - fn test_phase_times_i() { - // i * phase(θ) = phase(θ + π/2) - let quarter = Angle64::QUARTER_TURN; - let p = phase(quarter); - let ip = i * p; - - assert_eq!(ip.0, quarter + Angle64::QUARTER_TURN); - } - - #[test] - fn test_phase_times_neg_i() { - // -i * phase(θ) = phase(θ + 3π/2) - let quarter = Angle64::QUARTER_TURN; - let p = phase(quarter); - let nip = -i * p; - - assert_eq!(nip.0, quarter + Angle64::QUARTER_TURN + Angle64::HALF_TURN); - } - - #[test] - fn test_phase_equivalence_with_i() { - // phase(π/2) * X should be equivalent to i * X - // Since π/2 is a quarter turn, the phase gets absorbed into the PauliString - let op1 = phase(Angle64::QUARTER_TURN) * X(0); - let op2 = i * X(0); - - // Both should be Pauli with phase +i - if let (Operator::Pauli(ps1), Operator::Pauli(ps2)) = (&op1, &op2) { - assert_eq!(ps1.phase(), QuarterPhase::PlusI); - assert_eq!(ps2.phase(), QuarterPhase::PlusI); - } else { - panic!("Expected Pauli variants, got {op1:?} and {op2:?}"); - } - } - - #[test] - fn test_phase_zero_is_identity() { - // phase(0) * X should simplify to just X - let op = phase(Angle64::ZERO) * X(0); - - // with_phase returns self when phase is zero - assert!(matches!(op, Operator::Pauli(_))); - if let Operator::Pauli(ps) = op { - assert_eq!(ps.phase(), QuarterPhase::PlusOne); - } - } - -// --- Macro tests --- - - #[test] - fn test_angle_macro_pi() { - assert_eq!(crate::angle!(pi), Angle64::HALF_TURN); - } - - #[test] - fn test_angle_macro_pi_over_2() { - assert_eq!(crate::angle!(pi / 2), Angle64::QUARTER_TURN); - } - - #[test] - fn test_angle_macro_pi_over_4() { - // pi/4 = 1/8 turn - assert_eq!(crate::angle!(pi / 4), Angle64::from_turn_ratio(1, 8)); - } - - #[test] - fn test_angle_macro_2_pi_over_3() { - // 2*pi/3 = 2/6 = 1/3 turn - assert_eq!(crate::angle!(2 * pi / 3), Angle64::from_turn_ratio(1, 3)); - } - - #[test] - fn test_angle_macro_4_pi_over_3() { - // 4*pi/3 = 4/6 = 2/3 turn - assert_eq!(crate::angle!(4 * pi / 3), Angle64::from_turn_ratio(2, 3)); - } - - #[test] - fn test_angle_macro_negative() { - // -pi/2 should be the negative of pi/2 - let neg = crate::angle!(-pi / 2); - let pos = crate::angle!(pi / 2); - assert_eq!(neg, Angle64::ZERO - pos); - } - - #[test] - fn test_phase_macro_basic() { - // phase!(pi/4) should create a PhaseValue - let p = crate::phase!(pi / 4); - assert_eq!(p.0, Angle64::from_turn_ratio(1, 8)); - } - - #[test] - fn test_phase_macro_with_operator() { - // phase!(pi/2) * X should be same as i * X - // Since pi/2 is a quarter turn, the phase gets absorbed into PauliString - let op1 = crate::phase!(pi / 2) * X(0); - let op2 = i * X(0); - - // Both should be Pauli with phase +i - if let (Operator::Pauli(ps1), Operator::Pauli(ps2)) = (&op1, &op2) { - assert_eq!(ps1.phase(), QuarterPhase::PlusI); - assert_eq!(ps2.phase(), QuarterPhase::PlusI); - } else { - panic!("Expected Pauli variants, got {op1:?} and {op2:?}"); - } - } - - #[test] - fn test_phase_macro_exact_cancellation() { - // 8 * (pi/4) should exactly equal 2*pi = 0 - let eighth = crate::angle!(pi / 4); - let full = eighth + eighth + eighth + eighth + eighth + eighth + eighth + eighth; - assert_eq!(full, Angle64::ZERO); - } - -// --- Turn macro tests --- - - #[test] - fn test_turn_macro_quarter() { - assert_eq!(crate::turn!(1 / 4), Angle64::QUARTER_TURN); - } - - #[test] - fn test_turn_macro_half() { - assert_eq!(crate::turn!(1 / 2), Angle64::HALF_TURN); - } - - #[test] - fn test_turn_macro_eighth() { - // 1/8 turn = T gate phase = pi/4 radians - assert_eq!(crate::turn!(1 / 8), crate::angle!(pi / 4)); - } - - #[test] - fn test_turn_macro_third() { - // 1/3 turn - assert_eq!(crate::turn!(1 / 3), Angle64::from_turn_ratio(1, 3)); - } - - #[test] - fn test_turn_macro_two_thirds() { - // 2/3 turn - assert_eq!(crate::turn!(2 / 3), Angle64::from_turn_ratio(2, 3)); - } - - #[test] - fn test_turn_vs_angle_equivalence() { - // turn!(1/4) should equal angle!(pi/2) - assert_eq!(crate::turn!(1 / 4), crate::angle!(pi / 2)); - - // turn!(1/8) should equal angle!(pi/4) - assert_eq!(crate::turn!(1 / 8), crate::angle!(pi / 4)); - - // turn!(1/2) should equal angle!(pi) - assert_eq!(crate::turn!(1 / 2), crate::angle!(pi)); - } - - #[test] - fn test_phase_turn_macro_basic() { - let p = crate::phase_turn!(1 / 8); - assert_eq!(p.0, Angle64::from_turn_ratio(1, 8)); - } - - #[test] - fn test_phase_turn_macro_with_operator() { - // phase_turn!(1/4) * X should be same as i * X (quarter turn = i) - // Since quarter turn is a quarter phase, it gets absorbed into the PauliString - let op1 = crate::phase_turn!(1 / 4) * X(0); - let op2 = i * X(0); - - // Both should be Pauli with phase +i - if let (Operator::Pauli(ps1), Operator::Pauli(ps2)) = (&op1, &op2) { - assert_eq!(ps1.phase(), QuarterPhase::PlusI); - assert_eq!(ps2.phase(), QuarterPhase::PlusI); - } else { - panic!("Expected Pauli variants, got {op1:?} and {op2:?}"); - } - } - - #[test] - fn test_turn_exact_cancellation() { - // 8 * (1/8 turn) should exactly equal 1 full turn = 0 - let eighth = crate::turn!(1 / 8); - let full = eighth + eighth + eighth + eighth + eighth + eighth + eighth + eighth; - assert_eq!(full, Angle64::ZERO); - } - -// --- Pauli equivalence tests --- - - #[test] - fn test_is_pauli_equivalent_pauli() { - assert!(X(0).is_pauli_equivalent()); - assert!(Y(1).is_pauli_equivalent()); - assert!(Z(2).is_pauli_equivalent()); - assert!((X(0) & Y(1)).is_pauli_equivalent()); - } - - #[test] - fn test_is_pauli_equivalent_rotation() { - // Half-turn rotations are Pauli-equivalent - assert!(RX(Angle64::HALF_TURN, 0).is_pauli_equivalent()); - assert!(RY(Angle64::HALF_TURN, 0).is_pauli_equivalent()); - assert!(RZ(Angle64::HALF_TURN, 0).is_pauli_equivalent()); - - // Quarter-turn rotations are not - assert!(!RX(Angle64::QUARTER_TURN, 0).is_pauli_equivalent()); - assert!(!RZ(Angle64::QUARTER_TURN, 0).is_pauli_equivalent()); - } - - #[test] - #[allow(clippy::similar_names)] - fn test_try_to_pauli_rotation() { - // RX(π) = X - let rx_pi = RX(Angle64::HALF_TURN, 0); - let converted = rx_pi.try_to_pauli().expect("Should convert"); - if let Operator::Pauli(ps) = converted { - assert_eq!(ps.get(0), crate::Pauli::X); - } else { - panic!("Expected Pauli variant"); - } - - // RY(π) = Y - let ry_pi = RY(Angle64::HALF_TURN, 1); - let converted = ry_pi.try_to_pauli().expect("Should convert"); - if let Operator::Pauli(ps) = converted { - assert_eq!(ps.get(1), crate::Pauli::Y); - } else { - panic!("Expected Pauli variant"); - } - - // RZ(π) = Z - let rz_pi = RZ(Angle64::HALF_TURN, 2); - let converted = rz_pi.try_to_pauli().expect("Should convert"); - if let Operator::Pauli(ps) = converted { - assert_eq!(ps.get(2), crate::Pauli::Z); - } else { - panic!("Expected Pauli variant"); - } - } - - #[test] - fn test_try_to_pauli_non_pauli() { - // Quarter-turn rotations should not convert - assert!(RX(Angle64::QUARTER_TURN, 0).try_to_pauli().is_none()); - assert!(RZ(Angle64::QUARTER_TURN, 0).try_to_pauli().is_none()); - } - -// --- Multi-qubit syntax tests --- - - #[test] - fn test_x_multi_qubit() { - // Xs([0, 2, 5]) should be equivalent to X(0) & X(2) & X(5) - let multi = Xs([0, 2, 5]); - let tensor = X(0) & X(2) & X(5); - - // Both should be Pauli variants with the same content - if let (Operator::Pauli(ps1), Operator::Pauli(ps2)) = (&multi, &tensor) { - assert_eq!(ps1.get(0), crate::Pauli::X); - assert_eq!(ps1.get(2), crate::Pauli::X); - assert_eq!(ps1.get(5), crate::Pauli::X); - assert_eq!(ps1, ps2); - } else { - panic!("Expected Pauli variants"); - } - } - - #[test] - fn test_t_multi_qubit() { - // Ts([0, 1, 2]) should be a tensor of T gates - let multi = Ts([0, 1, 2]); - - if let Operator::Tensor(parts) = multi { - assert_eq!(parts.len(), 3); - // Each should be a rotation - assert!(matches!(&parts[0], Operator::Rotation { .. })); - assert!(matches!(&parts[1], Operator::Rotation { .. })); - assert!(matches!(&parts[2], Operator::Rotation { .. })); - } else { - panic!("Expected Tensor variant, got {multi:?}"); - } - } - - #[test] - fn test_h_multi_qubit() { - // Hs([0, 1]) should be a tensor of H gates - let multi = Hs([0, 1]); - - if let Operator::Tensor(parts) = multi { - assert_eq!(parts.len(), 2); - // Each should be a Compose (H = RZ * RY) - assert!(matches!(&parts[0], Operator::Compose(_))); - assert!(matches!(&parts[1], Operator::Compose(_))); - } else { - panic!("Expected Tensor variant, got {multi:?}"); - } - } - - #[test] - fn test_single_qubit_still_works() { - // Single qubit syntax should still work - let x = X(0); - let t = T(1); - let h = H(2); - - assert!(matches!(x, Operator::Pauli(_))); - assert!(matches!(t, Operator::Rotation { .. })); - assert!(matches!( - h, - Operator::Gate { - gate_type: GateType::H, - .. - } - )); - } - - #[test] - fn test_range_syntax() { - // Range syntax: Xs(0..3) = X(0) & X(1) & X(2) - let multi_range = Xs(0..3); - let tensor = X(0) & X(1) & X(2); - - if let (Operator::Pauli(ps1), Operator::Pauli(ps2)) = (&multi_range, &tensor) { - assert_eq!(ps1, ps2); - } else { - panic!("Expected Pauli variants"); - } - } - - #[test] - fn test_range_inclusive_syntax() { - // RangeInclusive syntax: Zs(1..=3) = Z(1) & Z(2) & Z(3) - let multi_range = Zs(1..=3); - let tensor = Z(1) & Z(2) & Z(3); - - if let (Operator::Pauli(ps1), Operator::Pauli(ps2)) = (&multi_range, &tensor) { - assert_eq!(ps1, ps2); - } else { - panic!("Expected Pauli variants"); - } - } - - #[test] - fn test_identity_range_syntax() { - // Is(0..=2) should create identity operators on qubits 0, 1, 2 - let identities = Is(0..=2); - - if let Operator::Tensor(parts) = identities { - assert_eq!(parts.len(), 3); - for part in &parts { - assert!(part.is_identity()); - } - } else { - panic!("Expected Tensor variant, got {identities:?}"); - } - } - - #[test] - #[should_panic(expected = "empty range not allowed")] - fn test_empty_range_panics() { - let _ = Xs(0..0); - } - - #[test] - #[should_panic(expected = "empty range not allowed")] - #[allow(clippy::reversed_empty_ranges)] // Intentionally testing empty range - fn test_empty_range_inclusive_panics() { - // 1..=0 is empty - let _ = Zs(1..=0); - } - - #[test] - fn test_single_element_range() { - // Xs(0..1) should be equivalent to X(0) - let from_range = Xs(0..1); - let direct = X(0); - - if let (Operator::Pauli(ps1), Operator::Pauli(ps2)) = (&from_range, &direct) { - assert_eq!(ps1, ps2); - } else { - panic!("Expected Pauli variants"); - } - } - - #[test] - fn test_single_element_range_inclusive() { - // Ts(2..=2) should be equivalent to T(2) - let from_range = Ts(2..=2); - let direct = T(2); - - // Both should be Rotation variants - if let ( - Operator::Rotation { - angle: a1, - rotation_type: r1, - .. - }, - Operator::Rotation { - angle: a2, - rotation_type: r2, - .. - }, - ) = (&from_range, &direct) - { - assert_eq!(a1, a2); - assert_eq!(r1, r2); - } else { - panic!("Expected Rotation variants, got {from_range:?} and {direct:?}"); - } - } - -// --- Conjugation tests --- - // Two conjugation conventions: - // A.conj(U) = U * A * U† (stabilizer update: S →USU† when applying U) - // A.conjdg(U) = U† * A * U (Heisenberg picture: A → U†AU) - - #[test] - fn test_conj_pauli_by_pauli() { - // X.conj(Z) = Z * X * Z† = Z * X * Z = -X (since Z is self-adjoint) - // ZX = -XZ, so ZXZ = -XZZ = -X - let x = X(0); - let z = Z(0); - let result = x.conj(&z); - - // conj returns a Compose, simplify to get the Pauli - let simplified = result.simplify(); - if let Operator::Pauli(ps) = simplified { - assert_eq!(ps.get(0), crate::Pauli::X); - assert_eq!(ps.phase(), QuarterPhase::MinusOne); - } else { - panic!("Expected Pauli variant, got {simplified:?}"); - } - } - - #[test] - fn test_conjdg_pauli_by_pauli() { - // X.conjdg(Z) = Z† * X * Z = Z * X * Z = -X (since Z is self-adjoint) - // Same result as conj for self-adjoint gates - let x = X(0); - let z = Z(0); - let result = x.conjdg(&z); - - let simplified = result.simplify(); - if let Operator::Pauli(ps) = simplified { - assert_eq!(ps.get(0), crate::Pauli::X); - assert_eq!(ps.phase(), QuarterPhase::MinusOne); - } else { - panic!("Expected Pauli variant, got {simplified:?}"); - } - } - - #[test] - fn test_conj_produces_compose() { - // A.conj(B) = B * A * B† produces a Compose - let x = X(0); - let h = H(0); - let result = x.conj(&h); - - // Result is Compose(H, X, H†) - assert!(matches!(result, Operator::Compose(_))); - } - - #[test] - fn test_conj_z_by_z() { - // Z.conj(Z) = Z * Z * Z† = Z * Z * Z = Z (since Z² = I, Z³ = Z) - let z = Z(0); - let result = z.conj(&z); - - let simplified = result.simplify(); - if let Operator::Pauli(ps) = simplified { - assert_eq!(ps.get(0), crate::Pauli::Z); - assert_eq!(ps.phase(), QuarterPhase::PlusOne); - } else { - panic!("Expected Pauli variant, got {simplified:?}"); - } - } - - #[test] - fn test_conj_structure_sz_gate() { - // X.conj(SZ) = SZ * X * SZ† should produce Compose with SZ first, X middle, SZ† last - let x = X(0); - let sz = SZ(0); - let result = x.conj(&sz); - - // Verify structure: Compose([SZ, X, SZ†]) - if let Operator::Compose(parts) = result { - assert_eq!(parts.len(), 3); - // First element is SZ (positive angle) - assert!(matches!( - &parts[0], - Operator::Rotation { - rotation_type: RotationType::RZ, - .. - } - )); - // Middle element is X - assert!(matches!(&parts[1], Operator::Pauli(_))); - // Last element is SZ† (negative angle) - assert!(matches!( - &parts[2], - Operator::Rotation { - rotation_type: RotationType::RZ, - .. - } - )); - } else { - panic!("Expected Compose variant, got {result:?}"); - } - } - - #[test] - fn test_conjdg_structure_sz_gate() { - // X.conjdg(SZ) = SZ† * X * SZ should produce Compose with SZ† first, X middle, SZ last - let x = X(0); - let sz = SZ(0); - let result = x.conjdg(&sz); - - // Verify structure: Compose([SZ†, X, SZ]) - if let Operator::Compose(parts) = result { - assert_eq!(parts.len(), 3); - // First element is SZ† (negative angle) - assert!(matches!( - &parts[0], - Operator::Rotation { - rotation_type: RotationType::RZ, - .. - } - )); - // Middle element is X - assert!(matches!(&parts[1], Operator::Pauli(_))); - // Last element is SZ (positive angle) - assert!(matches!( - &parts[2], - Operator::Rotation { - rotation_type: RotationType::RZ, - .. - } - )); - } else { - panic!("Expected Compose variant, got {result:?}"); - } - } - - #[test] - fn test_conj_conjdg_inverse_relationship() { - // For any operator A and gate U: - // A.conj(U).conjdg(U) should give back A (up to simplification) - // Because (UAU†).conjdg(U) = U†(UAU†)U = A - let x = X(0); - let sz = SZ(0); - - let forward = x.clone().conj(&sz); // SZ X SZ† - let back = forward.conjdg(&sz); // SZ† (SZ X SZ†) SZ = X - - let simplified = back.simplify(); - if let Operator::Pauli(ps) = simplified { - assert_eq!(ps.get(0), crate::Pauli::X); - assert_eq!(ps.phase(), QuarterPhase::PlusOne); - } else { - panic!("Expected Pauli variant, got {simplified:?}"); - } - } - -// --- Weight tests --- - - #[test] - fn test_weight_single_pauli() { - assert_eq!(X(0).weight(), 1); - assert_eq!(Y(1).weight(), 1); - assert_eq!(Z(2).weight(), 1); - } - - #[test] - fn test_weight_identity() { - // weight() returns number of qubits acted on - // I(0) = RZ(0, 0) acts on qubit 0 - assert_eq!(I(0).weight(), 1); - } - - #[test] - fn test_weight_tensor_product() { - let op = X(0) & Y(1) & Z(2); - assert_eq!(op.weight(), 3); - } - - #[test] - fn test_weight_tensor_with_identity() { - // Id tensored still counts as acting on that qubit - let op = X(0) & I(1) & Z(2); - assert_eq!(op.weight(), 3); - } - - #[test] - fn test_weight_rotation() { - // Rotations have weight equal to the number of qubits they act on - assert_eq!(RX(Angle64::QUARTER_TURN, 0).weight(), 1); - assert_eq!(RZZ(Angle64::QUARTER_TURN, 0, 1).weight(), 2); - } - - #[test] - fn test_weight_gate() { - assert_eq!(H(0).weight(), 1); - assert_eq!(CX(0, 1).weight(), 2); - assert_eq!(CCX(0, 1, 2).weight(), 3); - } - -// --- is_hermitian tests --- - - #[test] - fn test_is_hermitian_paulis() { - // All Paulis are Hermitian - assert!(X(0).is_hermitian()); - assert!(Y(0).is_hermitian()); - assert!(Z(0).is_hermitian()); - assert!(I(0).is_hermitian()); - } - - #[test] - fn test_is_hermitian_pauli_tensor() { - // Tensor products of Paulis are Hermitian - let op = X(0) & Y(1) & Z(2); - assert!(op.is_hermitian()); - } - - #[test] - fn test_is_hermitian_hadamard() { - // H is Hermitian (H = H†) - assert!(H(0).is_hermitian()); - } - - #[test] - fn test_is_hermitian_rotation_not() { - // General rotations are not Hermitian (unless angle is 0 or π) - assert!(!RZ(Angle64::QUARTER_TURN, 0).is_hermitian()); - assert!(!T(0).is_hermitian()); - assert!(!SZ(0).is_hermitian()); - } - - #[test] - fn test_is_hermitian_rotation_half_turn() { - // Half-turn rotations are Hermitian (up to global phase) - // RX(π) = -iX, which is Hermitian - assert!(RX(Angle64::HALF_TURN, 0).is_hermitian()); - assert!(RY(Angle64::HALF_TURN, 0).is_hermitian()); - assert!(RZ(Angle64::HALF_TURN, 0).is_hermitian()); - } - -// --- pow tests --- - - #[test] - fn test_pow_zero() { - // X^0 = I - let x = X(0); - let result = x.pow(0); - assert!(result.is_identity()); - } - - #[test] - fn test_pow_one() { - // X^1 = X - let x = X(0); - let result = x.pow(1); - if let Operator::Pauli(ps) = result { - assert_eq!(ps.get(0), crate::Pauli::X); - } else { - panic!("Expected Pauli"); - } - } - - #[test] - fn test_pow_two_pauli() { - // X^2 = I after simplification - let x = X(0); - let result = x.pow(2).simplify(); - assert!(result.is_identity()); - } - - #[test] - fn test_pow_creates_compose() { - // pow(n) creates a Compose of n copies without simplification - let t = T(0); - let result = t.pow(3); - assert!(matches!(result, Operator::Compose(_))); - } - - #[test] - fn test_pow_rotation_simplify() { - // T^2 = S (RZ(π/4)^2 = RZ(π/2)) after simplification - let t = T(0); - let result = t.pow(2).simplify(); - - if let Operator::Rotation { - angle, - rotation_type, - .. - } = result - { - assert_eq!(rotation_type, RotationType::RZ); - assert_eq!(angle, Angle64::QUARTER_TURN); - } else { - panic!("Expected Rotation, got {result:?}"); - } - } - - #[test] - fn test_pow_four_t_simplify() { - // T^4 = Z (RZ(π/4)^4 = RZ(π)) after simplification - let t = T(0); - let result = t.pow(4).simplify(); - - if let Operator::Rotation { angle, .. } = result { - assert_eq!(angle, Angle64::HALF_TURN); - } else { - panic!("Expected Rotation, got {result:?}"); - } - } - - #[test] - fn test_pow_eight_t_simplify() { - // T^8 = I (RZ(π/4)^8 = RZ(2π) = I) after simplification - let t = T(0); - let result = t.pow(8).simplify(); - assert!(result.is_identity()); - } - -// --- commutes tests --- - - #[test] - fn test_commutes_same_pauli() { - // X commutes with X - let x1 = X(0); - let x2 = X(0); - assert_eq!(x1.commutes(&x2), Commutativity::Commutes); - } - - #[test] - fn test_commutes_different_paulis_same_qubit() { - // X and Z anticommute on same qubit - let x = X(0); - let z = Z(0); - assert_eq!(x.commutes(&z), Commutativity::AntiCommutes); - - // X and Y anticommute - let y = Y(0); - assert_eq!(x.commutes(&y), Commutativity::AntiCommutes); - - // Y and Z anticommute - assert_eq!(y.commutes(&z), Commutativity::AntiCommutes); - } - - #[test] - fn test_commutes_different_qubits() { - // Operators on different qubits always commute - let x0 = X(0); - let z1 = Z(1); - assert_eq!(x0.commutes(&z1), Commutativity::Commutes); - } - - #[test] - fn test_commutes_non_pauli_unknown() { - // Non-Pauli operators return Unknown - // I(0) is RZ(0, 0), not a Pauli variant - let id = I(0); - let x = X(0); - assert_eq!(id.commutes(&x), Commutativity::Unknown); - - let h = H(0); - assert_eq!(h.commutes(&x), Commutativity::Unknown); - } - - #[test] - fn test_commutes_pauli_strings() { - // XY and YX: overlap on both qubits, both anticommute -> commute - let xy = X(0) & Y(1); - let yx = Y(0) & X(1); - assert_eq!(xy.commutes(&yx), Commutativity::Commutes); - - // XY and ZZ: both overlap, X-Z and Y-Z both anticommute -> commute - let zz = Z(0) & Z(1); - assert_eq!(xy.commutes(&zz), Commutativity::Commutes); - - // XZ and Y: only qubit 0 overlaps, X-Y anticommute - let xz = X(0) & Z(1); - let y = Y(0); - assert_eq!(xz.commutes(&y), Commutativity::AntiCommutes); - } - -// --- decompose tests --- - - #[test] - fn test_decompose_single_pauli() { - let x = X(0); - let gates = x.decompose(); - assert_eq!(gates.len(), 1); - assert_eq!(gates[0].gate_type, GateType::X); - } - - #[test] - fn test_decompose_pauli_tensor() { - let op = X(0) & Y(1) & Z(2); - let gates = op.decompose(); - assert_eq!(gates.len(), 3); - - let gate_types: Vec<_> = gates.iter().map(|g| g.gate_type).collect(); - assert!(gate_types.contains(&GateType::X)); - assert!(gate_types.contains(&GateType::Y)); - assert!(gate_types.contains(&GateType::Z)); - } - - #[test] - fn test_decompose_identity() { - // I(0) = RZ(0, 0), so it decomposes to an RZ gate with angle 0 - let id = I(0); - let gates = id.decompose(); - assert_eq!(gates.len(), 1); - assert_eq!(gates[0].gate_type, GateType::RZ); - assert_eq!(gates[0].angles[0], Angle64::ZERO); - } - - #[test] - fn test_decompose_pauli_identity_empty() { - // A true Pauli identity (from PauliString) decomposes to empty - let ps = PauliString::identity(); - let op = Operator::Pauli(ps); - let gates = op.decompose(); - assert!(gates.is_empty()); - } - - #[test] - fn test_decompose_rotation() { - let t = T(0); - let gates = t.decompose(); - assert_eq!(gates.len(), 1); - assert_eq!(gates[0].gate_type, GateType::RZ); - assert_eq!(gates[0].angles.len(), 1); - } - - #[test] - fn test_decompose_gate() { - let cx = CX(0, 1); - let gates = cx.decompose(); - assert_eq!(gates.len(), 1); - assert_eq!(gates[0].gate_type, GateType::CX); - } - - #[test] - fn test_decompose_composition() { - let circuit = SZ(0) * H(0) * X(0); // X, then H, then S - let gates = circuit.decompose(); - assert_eq!(gates.len(), 3); - } - - #[test] - fn test_decompose_adjoint() { - let t = T(0); - let t_dg = t.dg(); - let gates = t_dg.decompose(); - - assert_eq!(gates.len(), 1); - assert_eq!(gates[0].gate_type, GateType::RZ); - // Angle should be negated - let expected_angle = Angle64::ZERO - (Angle64::HALF_TURN / 4); - assert_eq!(gates[0].angles[0], expected_angle); - } - - #[test] - fn test_decompose_adjoint_named_gate() { - // S† should decompose to SZdg - let s = SZ(0); - let s_dg = s.dg(); - let gates = s_dg.decompose(); - - // S is a rotation, S† negates the angle - assert_eq!(gates.len(), 1); - assert_eq!(gates[0].gate_type, GateType::RZ); - } - -// --- as_pauli_string / into_pauli_string tests --- - - #[test] - fn test_as_pauli_string_pauli() { - let x = X(0); - let ps = x.as_pauli_string(); - assert!(ps.is_some()); - let ps = ps.unwrap(); - assert_eq!(ps.get(0), crate::Pauli::X); - } - - #[test] - fn test_as_pauli_string_non_pauli() { - let h = H(0); - assert!(h.as_pauli_string().is_none()); - - let t = T(0); - assert!(t.as_pauli_string().is_none()); - } - - #[test] - fn test_into_pauli_string_pauli() { - let xy = X(0) & Y(1); - let ps = xy.into_pauli_string(); - assert!(ps.is_some()); - let ps = ps.unwrap(); - assert_eq!(ps.get(0), crate::Pauli::X); - assert_eq!(ps.get(1), crate::Pauli::Y); - } - - #[test] - fn test_into_pauli_string_with_phase() { - let op = i * X(0); - let ps = op.into_pauli_string(); - assert!(ps.is_some()); - let ps = ps.unwrap(); - assert_eq!(ps.get(0), crate::Pauli::X); - assert_eq!(ps.phase(), QuarterPhase::PlusI); - } -} diff --git a/crates/pecos-core/src/pauli.rs b/crates/pecos-core/src/pauli.rs index a20ef5976..87050ef04 100644 --- a/crates/pecos-core/src/pauli.rs +++ b/crates/pecos-core/src/pauli.rs @@ -13,6 +13,12 @@ pub mod algebra; pub mod constructors; +// Re-export constructors at the `pauli` level so `use pecos_core::pauli::*` works. +pub use constructors::{I, X, Xs, Y, Ys, Z, Zs}; + +// Re-export key types so `use pecos_core::pauli::*` gives the full Pauli toolkit. +pub use pauli_string::PauliString; + #[allow(clippy::module_name_repetitions)] pub mod pauli_bitmap; diff --git a/crates/pecos-core/src/pauli/constructors.rs b/crates/pecos-core/src/pauli/constructors.rs index fc67d9a76..507c509d9 100644 --- a/crates/pecos-core/src/pauli/constructors.rs +++ b/crates/pecos-core/src/pauli/constructors.rs @@ -18,7 +18,7 @@ //! # Examples //! //! ``` -//! use pecos_core::pauli::constructors::*; +//! use pecos_core::pauli::*; //! use pecos_core::PauliOperator; //! //! // Single-qubit Paulis @@ -88,7 +88,7 @@ impl QubitArgs for std::ops::RangeInclusive { /// # Examples /// /// ``` -/// use pecos_core::pauli::constructors::X; +/// use pecos_core::pauli::X; /// use pecos_core::{Pauli, PauliOperator}; /// /// let p = X(0); @@ -131,7 +131,7 @@ pub fn I() -> PauliString { /// # Examples /// /// ``` -/// use pecos_core::pauli::constructors::Xs; +/// use pecos_core::pauli::Xs; /// use pecos_core::PauliOperator; /// /// let p = Xs([0, 1, 2]); @@ -166,7 +166,7 @@ pub fn Ys(qubits: impl QubitArgs) -> PauliString { /// # Examples /// /// ``` -/// use pecos_core::pauli::constructors::Zs; +/// use pecos_core::pauli::Zs; /// use pecos_core::PauliOperator; /// /// let stab = Zs([0, 1]); diff --git a/crates/pecos-core/src/unitary.rs b/crates/pecos-core/src/unitary.rs new file mode 100644 index 000000000..cf37279e9 --- /dev/null +++ b/crates/pecos-core/src/unitary.rs @@ -0,0 +1,29 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License.You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Unitary gate algebra namespace. +//! +//! Re-exports the full unitary-level API so users can write: +//! +//! ``` +//! use pecos_core::unitary::*; +//! use pecos_core::Angle64; +//! +//! let circuit = T(1) * CX(0, 1) * H(0); +//! let layer = RZ(Angle64::HALF_TURN / 4, 0) & H(1); +//! ``` + +pub use crate::unitary_rep::{ + CCX, CX, CXs, CY, CYs, CZ, CZs, Commutativity, H, Hs, I, Is, ParseUnitaryRepError, PhaseValue, + QubitPairs, Qubits, RX, RXX, RXXs, RXs, RY, RYY, RYYs, RYs, RZ, RZZ, RZZs, RZs, RotationType, + SWAP, SWAPs, SX, SXs, SY, SYs, SZ, SZs, T, Ts, Unitary, UnitaryRep, X, Xs, Y, Ys, Z, Zs, phase, +}; diff --git a/crates/pecos-core/src/unitary_rep.rs b/crates/pecos-core/src/unitary_rep.rs index 95eac8d96..610d86ff9 100644 --- a/crates/pecos-core/src/unitary_rep.rs +++ b/crates/pecos-core/src/unitary_rep.rs @@ -29,7 +29,7 @@ //! # Examples //! //! ``` -//! use pecos_core::unitary_rep::*; +//! use pecos_core::unitary::*; //! use pecos_core::Angle64; //! //! // Build a circuit: H on q0, then CX(0,1), then T on q1 @@ -68,7 +68,7 @@ use std::str::FromStr; /// /// ``` /// use pecos_core::{phase, Angle64}; -/// use pecos_core::unitary_rep::X; +/// use pecos_core::unitary::X; /// /// // e^{iπ/4} * X - exact, no floating point /// let op = phase!(pi / 4) * X(0); @@ -95,7 +95,7 @@ macro_rules! phase { /// /// ``` /// use pecos_core::phase_turn; -/// use pecos_core::unitary_rep::X; +/// use pecos_core::unitary::X; /// /// // T gate phase: e^{i * 2π/8} = e^{iπ/4} /// let op = phase_turn!(1 / 8) * X(0); @@ -386,7 +386,7 @@ pub enum Commutativity { /// /// Enables pluralized gate functions to accept various qubit collections: /// ``` -/// use pecos_core::unitary_rep::*; +/// use pecos_core::unitary::*; /// use pecos_core::QubitId; /// /// // Multiple qubits via Xs - equivalent to X(0) & X(2) & X(5) @@ -498,7 +498,7 @@ impl Qubits { /// Wrapper for qubit pairs used by pluralized two-qubit gates. /// /// ``` -/// use pecos_core::unitary_rep::*; +/// use pecos_core::unitary::*; /// use pecos_core::QubitId; /// /// // Multiple CX gates via CXs @@ -1251,7 +1251,7 @@ impl Mul<&UnitaryRep> for NegImaginaryUnit { /// /// # Example /// ``` -/// use pecos_core::unitary_rep::{phase, X}; +/// use pecos_core::unitary::{phase, X}; /// use pecos_core::Angle64; /// /// // Create a phase of e^{iπ/4} @@ -1267,7 +1267,7 @@ pub struct PhaseValue(pub Angle64); /// /// # Example /// ``` -/// use pecos_core::unitary_rep::{phase, X, Z}; +/// use pecos_core::unitary::{phase, X, Z}; /// use pecos_core::Angle64; /// /// // e^{iπ/4} * X @@ -1384,7 +1384,7 @@ impl UnitaryRep { /// # Example /// /// ``` - /// use pecos_core::unitary_rep::{Xs, Zs}; + /// use pecos_core::unitary::{Xs, Zs}; /// use pecos_core::PauliOperator; /// /// // Tensor of Paulis on disjoint qubits @@ -1643,7 +1643,7 @@ impl UnitaryRep { /// # Example /// /// ``` - /// use pecos_core::unitary_rep::{X, Z, H, T}; + /// use pecos_core::unitary::{X, Z, H, T}; /// /// // Stabilizer update: applying H to qubit 0 /// let stabilizer = X(0) & Z(1); @@ -1668,7 +1668,7 @@ impl UnitaryRep { /// # Example /// /// ``` - /// use pecos_core::unitary_rep::{X, H}; + /// use pecos_core::unitary::{X, H}; /// /// // Heisenberg evolution: how X evolves under H /// let evolved = X(0).conjdg(&H(0)); // H† X H @@ -1683,7 +1683,7 @@ impl UnitaryRep { /// # Example /// /// ``` - /// use pecos_core::unitary_rep::{X, Y}; + /// use pecos_core::unitary::{X, Y}; /// use pecos_core::{GlobalPhase, QuarterPhase}; /// /// let op = X(0); @@ -1708,7 +1708,7 @@ impl UnitaryRep { /// # Example /// /// ``` - /// use pecos_core::unitary_rep::{X, Z, CX}; + /// use pecos_core::unitary::{X, Z, CX}; /// /// assert_eq!(X(0).weight(), 1); /// assert_eq!((X(0) & Z(2)).weight(), 2); @@ -1724,7 +1724,7 @@ impl UnitaryRep { /// # Example /// /// ``` - /// use pecos_core::unitary_rep::I; + /// use pecos_core::unitary::I; /// /// assert!(I(0).is_identity()); /// ``` @@ -1744,7 +1744,7 @@ impl UnitaryRep { /// # Example /// /// ``` - /// use pecos_core::unitary_rep::{X, Y, Z, H, T}; + /// use pecos_core::unitary::{X, Y, Z, H, T}; /// /// // Paulis are Hermitian /// assert!(X(0).is_hermitian()); @@ -1806,7 +1806,7 @@ impl UnitaryRep { /// # Example /// /// ``` - /// use pecos_core::unitary_rep::{X, H}; + /// use pecos_core::unitary::{X, H}; /// /// let x = X(0); /// let x2 = x.pow(2); // X * X = I @@ -1843,7 +1843,7 @@ impl UnitaryRep { /// # Example /// /// ``` - /// use pecos_core::unitary_rep::{X, Z, Commutativity}; + /// use pecos_core::unitary::{X, Z, Commutativity}; /// /// let a = X(0); /// let b = Z(0); @@ -1876,7 +1876,7 @@ impl UnitaryRep { /// # Example /// /// ``` - /// use pecos_core::unitary_rep::{X, H, RZ}; + /// use pecos_core::unitary::{X, H, RZ}; /// use pecos_core::Angle64; /// /// assert!(X(0).is_unitary()); @@ -1896,7 +1896,7 @@ impl UnitaryRep { /// # Example /// /// ``` - /// use pecos_core::unitary_rep::{H, CX}; + /// use pecos_core::unitary::{H, CX}; /// /// let circuit = CX(0, 1) * H(0); // H then CX /// let gates = circuit.decompose(); diff --git a/crates/pecos-gpu-sims/src/gpu_noisy_sampler.rs b/crates/pecos-gpu-sims/src/gpu_noisy_sampler.rs index 7e7703f1d..fd6d752d8 100644 --- a/crates/pecos-gpu-sims/src/gpu_noisy_sampler.rs +++ b/crates/pecos-gpu-sims/src/gpu_noisy_sampler.rs @@ -326,9 +326,9 @@ impl NoiseSampler for BiasedDepolarizingNoiseSampler { } } -/// Operations that can be added to a circuit. +/// Ideal gates that can be added to a noisy sampler circuit. #[derive(Debug, Clone)] -pub enum CircuitOp { +pub enum Gate { // Single-qubit gates H(usize), S(usize), @@ -344,29 +344,39 @@ pub enum CircuitOp { // Measurements Mz(usize), +} - // Noise injection points - Noise1Q(usize), - Noise2Q(usize, usize), +/// Explicit noise injection point in a noisy sampler circuit. +#[derive(Debug, Clone)] +pub enum NoiseInjection { + OneQ(usize), + TwoQ(usize, usize), +} + +/// A circuit step for the noisy sampler. +#[derive(Debug, Clone)] +pub enum NoisyCircuitStep { + Gate(Gate), + Noise(NoiseInjection), } /// Builder for constructing circuits with noise injection points. #[derive(Default)] pub struct CircuitBuilder { - ops: Vec, + steps: Vec, } impl CircuitBuilder { /// Create a new empty circuit builder. #[must_use] pub fn new() -> Self { - Self { ops: Vec::new() } + Self { steps: Vec::new() } } /// Hadamard gate. pub fn h(&mut self, qubits: &[usize]) -> &mut Self { for &q in qubits { - self.ops.push(CircuitOp::H(q)); + self.steps.push(NoisyCircuitStep::Gate(Gate::H(q))); } self } @@ -374,7 +384,7 @@ impl CircuitBuilder { /// S gate (sqrt Z). pub fn s(&mut self, qubits: &[usize]) -> &mut Self { for &q in qubits { - self.ops.push(CircuitOp::S(q)); + self.steps.push(NoisyCircuitStep::Gate(Gate::S(q))); } self } @@ -382,7 +392,7 @@ impl CircuitBuilder { /// S-dagger gate. pub fn sdg(&mut self, qubits: &[usize]) -> &mut Self { for &q in qubits { - self.ops.push(CircuitOp::Sdg(q)); + self.steps.push(NoisyCircuitStep::Gate(Gate::Sdg(q))); } self } @@ -390,7 +400,7 @@ impl CircuitBuilder { /// Pauli X gate. pub fn x(&mut self, qubits: &[usize]) -> &mut Self { for &q in qubits { - self.ops.push(CircuitOp::X(q)); + self.steps.push(NoisyCircuitStep::Gate(Gate::X(q))); } self } @@ -398,7 +408,7 @@ impl CircuitBuilder { /// Pauli Y gate. pub fn y(&mut self, qubits: &[usize]) -> &mut Self { for &q in qubits { - self.ops.push(CircuitOp::Y(q)); + self.steps.push(NoisyCircuitStep::Gate(Gate::Y(q))); } self } @@ -406,7 +416,7 @@ impl CircuitBuilder { /// Pauli Z gate. pub fn z(&mut self, qubits: &[usize]) -> &mut Self { for &q in qubits { - self.ops.push(CircuitOp::Z(q)); + self.steps.push(NoisyCircuitStep::Gate(Gate::Z(q))); } self } @@ -414,7 +424,8 @@ impl CircuitBuilder { /// CNOT gate. pub fn cx(&mut self, pairs: &[(usize, usize)]) -> &mut Self { for &(control, target) in pairs { - self.ops.push(CircuitOp::Cx(control, target)); + self.steps + .push(NoisyCircuitStep::Gate(Gate::Cx(control, target))); } self } @@ -422,7 +433,7 @@ impl CircuitBuilder { /// CZ gate. pub fn cz(&mut self, pairs: &[(usize, usize)]) -> &mut Self { for &(a, b) in pairs { - self.ops.push(CircuitOp::Cz(a, b)); + self.steps.push(NoisyCircuitStep::Gate(Gate::Cz(a, b))); } self } @@ -430,7 +441,7 @@ impl CircuitBuilder { /// SWAP gate. pub fn swap(&mut self, pairs: &[(usize, usize)]) -> &mut Self { for &(a, b) in pairs { - self.ops.push(CircuitOp::Swap(a, b)); + self.steps.push(NoisyCircuitStep::Gate(Gate::Swap(a, b))); } self } @@ -438,7 +449,7 @@ impl CircuitBuilder { /// Measure qubit(s) in Z basis. pub fn mz(&mut self, qubits: &[usize]) -> &mut Self { for &q in qubits { - self.ops.push(CircuitOp::Mz(q)); + self.steps.push(NoisyCircuitStep::Gate(Gate::Mz(q))); } self } @@ -446,7 +457,8 @@ impl CircuitBuilder { /// Mark a noise injection point for single-qubit noise. pub fn noise_1q(&mut self, qubits: &[usize]) -> &mut Self { for &q in qubits { - self.ops.push(CircuitOp::Noise1Q(q)); + self.steps + .push(NoisyCircuitStep::Noise(NoiseInjection::OneQ(q))); } self } @@ -454,20 +466,21 @@ impl CircuitBuilder { /// Mark a noise injection point for two-qubit noise. pub fn noise_2q(&mut self, pairs: &[(usize, usize)]) -> &mut Self { for &(a, b) in pairs { - self.ops.push(CircuitOp::Noise2Q(a, b)); + self.steps + .push(NoisyCircuitStep::Noise(NoiseInjection::TwoQ(a, b))); } self } - /// Get the operations in this circuit. + /// Get the steps in this noisy sampler circuit. #[must_use] - pub fn ops(&self) -> &[CircuitOp] { - &self.ops + pub fn steps(&self) -> &[NoisyCircuitStep] { + &self.steps } /// Clear the circuit for reuse. pub fn clear(&mut self) { - self.ops.clear(); + self.steps.clear(); } } @@ -522,7 +535,7 @@ impl GpuNoisySampler { // Build the circuit once let mut builder = CircuitBuilder::new(); circuit_fn(&mut builder); - let ops = builder.ops().to_vec(); + let steps = builder.steps().to_vec(); let mut results = Vec::with_capacity(shots); @@ -542,36 +555,36 @@ impl GpuNoisySampler { let mut outcomes = Vec::new(); // Execute the circuit with noise injection - for op in &ops { - match op { - CircuitOp::H(q) => { + for step in &steps { + match step { + NoisyCircuitStep::Gate(Gate::H(q)) => { sim.h(&[QubitId(*q)]); } - CircuitOp::S(q) => { + NoisyCircuitStep::Gate(Gate::S(q)) => { sim.sz(&[QubitId(*q)]); } - CircuitOp::Sdg(q) => { + NoisyCircuitStep::Gate(Gate::Sdg(q)) => { sim.szdg(&[QubitId(*q)]); } - CircuitOp::X(q) => { + NoisyCircuitStep::Gate(Gate::X(q)) => { sim.x(&[QubitId(*q)]); } - CircuitOp::Y(q) => { + NoisyCircuitStep::Gate(Gate::Y(q)) => { sim.y(&[QubitId(*q)]); } - CircuitOp::Z(q) => { + NoisyCircuitStep::Gate(Gate::Z(q)) => { sim.z(&[QubitId(*q)]); } - CircuitOp::Cx(ctrl, tgt) => { + NoisyCircuitStep::Gate(Gate::Cx(ctrl, tgt)) => { sim.cx(&[(QubitId(*ctrl), QubitId(*tgt))]); } - CircuitOp::Cz(a, b) => { + NoisyCircuitStep::Gate(Gate::Cz(a, b)) => { sim.cz(&[(QubitId(*a), QubitId(*b))]); } - CircuitOp::Swap(a, b) => { + NoisyCircuitStep::Gate(Gate::Swap(a, b)) => { sim.swap(&[(QubitId(*a), QubitId(*b))]); } - CircuitOp::Mz(q) => { + NoisyCircuitStep::Gate(Gate::Mz(q)) => { let results = sim.mz(&[QubitId(*q)]); let mut outcome = results[0].outcome; @@ -585,7 +598,7 @@ impl GpuNoisySampler { outcomes.push(outcome); } - CircuitOp::Noise1Q(q) => { + NoisyCircuitStep::Noise(NoiseInjection::OneQ(q)) => { // Sample and apply single-qubit noise match self.noise_sampler.sample_1q(*q) { Pauli::I => {} @@ -600,7 +613,7 @@ impl GpuNoisySampler { } } } - CircuitOp::Noise2Q(a, b) => { + NoisyCircuitStep::Noise(NoiseInjection::TwoQ(a, b)) => { // Sample and apply two-qubit noise let (pa, pb) = self.noise_sampler.sample_2q(*a, *b); match pa { @@ -688,13 +701,31 @@ mod tests { .noise_2q(&[(0, 1)]) .mz(&[0, 1]); - assert_eq!(builder.ops().len(), 6); - assert!(matches!(builder.ops()[0], CircuitOp::H(0))); - assert!(matches!(builder.ops()[1], CircuitOp::Noise1Q(0))); - assert!(matches!(builder.ops()[2], CircuitOp::Cx(0, 1))); - assert!(matches!(builder.ops()[3], CircuitOp::Noise2Q(0, 1))); - assert!(matches!(builder.ops()[4], CircuitOp::Mz(0))); - assert!(matches!(builder.ops()[5], CircuitOp::Mz(1))); + assert_eq!(builder.steps().len(), 6); + assert!(matches!( + builder.steps()[0], + NoisyCircuitStep::Gate(Gate::H(0)) + )); + assert!(matches!( + builder.steps()[1], + NoisyCircuitStep::Noise(NoiseInjection::OneQ(0)) + )); + assert!(matches!( + builder.steps()[2], + NoisyCircuitStep::Gate(Gate::Cx(0, 1)) + )); + assert!(matches!( + builder.steps()[3], + NoisyCircuitStep::Noise(NoiseInjection::TwoQ(0, 1)) + )); + assert!(matches!( + builder.steps()[4], + NoisyCircuitStep::Gate(Gate::Mz(0)) + )); + assert!(matches!( + builder.steps()[5], + NoisyCircuitStep::Gate(Gate::Mz(1)) + )); } #[test] @@ -715,23 +746,59 @@ mod tests { .noise_2q(&[(0, 1)]) .mz(&[0]); - assert_eq!(builder.ops().len(), 12); - assert!(matches!(builder.ops()[0], CircuitOp::H(0))); - assert!(matches!(builder.ops()[1], CircuitOp::S(0))); - assert!(matches!(builder.ops()[2], CircuitOp::Sdg(0))); - assert!(matches!(builder.ops()[3], CircuitOp::X(0))); - assert!(matches!(builder.ops()[4], CircuitOp::Y(0))); - assert!(matches!(builder.ops()[5], CircuitOp::Z(0))); - assert!(matches!(builder.ops()[6], CircuitOp::Cx(0, 1))); - assert!(matches!(builder.ops()[7], CircuitOp::Cz(0, 1))); - assert!(matches!(builder.ops()[8], CircuitOp::Swap(0, 1))); - assert!(matches!(builder.ops()[9], CircuitOp::Noise1Q(0))); - assert!(matches!(builder.ops()[10], CircuitOp::Noise2Q(0, 1))); - assert!(matches!(builder.ops()[11], CircuitOp::Mz(0))); + assert_eq!(builder.steps().len(), 12); + assert!(matches!( + builder.steps()[0], + NoisyCircuitStep::Gate(Gate::H(0)) + )); + assert!(matches!( + builder.steps()[1], + NoisyCircuitStep::Gate(Gate::S(0)) + )); + assert!(matches!( + builder.steps()[2], + NoisyCircuitStep::Gate(Gate::Sdg(0)) + )); + assert!(matches!( + builder.steps()[3], + NoisyCircuitStep::Gate(Gate::X(0)) + )); + assert!(matches!( + builder.steps()[4], + NoisyCircuitStep::Gate(Gate::Y(0)) + )); + assert!(matches!( + builder.steps()[5], + NoisyCircuitStep::Gate(Gate::Z(0)) + )); + assert!(matches!( + builder.steps()[6], + NoisyCircuitStep::Gate(Gate::Cx(0, 1)) + )); + assert!(matches!( + builder.steps()[7], + NoisyCircuitStep::Gate(Gate::Cz(0, 1)) + )); + assert!(matches!( + builder.steps()[8], + NoisyCircuitStep::Gate(Gate::Swap(0, 1)) + )); + assert!(matches!( + builder.steps()[9], + NoisyCircuitStep::Noise(NoiseInjection::OneQ(0)) + )); + assert!(matches!( + builder.steps()[10], + NoisyCircuitStep::Noise(NoiseInjection::TwoQ(0, 1)) + )); + assert!(matches!( + builder.steps()[11], + NoisyCircuitStep::Gate(Gate::Mz(0)) + )); // Test clear builder.clear(); - assert_eq!(builder.ops().len(), 0); + assert_eq!(builder.steps().len(), 0); } #[test] diff --git a/crates/pecos-gpu-sims/src/lib.rs b/crates/pecos-gpu-sims/src/lib.rs index b734d4cb3..d54c7eeb7 100644 --- a/crates/pecos-gpu-sims/src/lib.rs +++ b/crates/pecos-gpu-sims/src/lib.rs @@ -68,8 +68,8 @@ pub use gpu64::GpuStateVec64; pub type GpuStateVec = GpuStateVec64; pub use gpu_influence_sampler::{GpuInfluenceMapData, GpuInfluenceSampler, GpuSamplingResult}; pub use gpu_noisy_sampler::{ - BiasedDepolarizingNoiseSampler, CircuitBuilder, CircuitOp, DepolarizingNoiseSampler, - GpuNoisySampler, NoiseSampler, Pauli, ShotResult, + BiasedDepolarizingNoiseSampler, CircuitBuilder, DepolarizingNoiseSampler, Gate, + GpuNoisySampler, NoiseInjection, NoiseSampler, NoisyCircuitStep, Pauli, ShotResult, }; pub use gpu_pauli_prop::GpuPauliProp; pub use gpu_sampler::{GpuMeasurementSampler, GpuSampleResult}; diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs index a53e7c658..8232810ca 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs @@ -523,7 +523,7 @@ impl<'a> DemBuilder<'a> { ) { // Per-Pauli probabilities: custom weights or uniform p/3 let (px, py, pz) = if let Some(ref weights) = self.noise.p1_weights { - use pecos_core::pauli::constructors::{X, Y, Z}; + use pecos_core::pauli::{X, Y, Z}; ( self.noise.p1 * weights.weight_for(&X(0)), self.noise.p1 * weights.weight_for(&Y(0)), @@ -1360,14 +1360,14 @@ mod tests { use super::*; #[test] - fn test_from_circuit_tracks_pauli_operator_as_tracked_op() { - use pecos_core::pauli::constructors::X; + fn test_from_circuit_tracks_tracked_operator() { + use pecos_core::pauli::X; use pecos_quantum::DagCircuit; let mut circuit = DagCircuit::new(); circuit.pz(&[0]); circuit.h(&[0]); - circuit.pauli_operator_labeled("x_check", X(0)); + circuit.tracked_operator_labeled("x_check", X(0)); let dem = DemBuilder::from_circuit(&circuit, 0.03, 0.0, 0.0, 0.0); @@ -1388,13 +1388,13 @@ mod tests { } #[test] - fn test_pauli_operator_and_observable_use_distinct_tracked_ops() { - use pecos_core::pauli::constructors::Z; + fn test_tracked_operator_and_observable_use_distinct_tracked_ops() { + use pecos_core::pauli::Z; use pecos_quantum::{Attribute, DagCircuit}; let mut circuit = DagCircuit::new(); circuit.pz(&[0]); - circuit.pauli_operator_labeled("z_check", Z(0)); + circuit.tracked_operator_labeled("z_check", Z(0)); circuit.mz(&[0]); circuit.set_attr("num_measurements", Attribute::String("1".to_string())); circuit.set_attr( diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs index edc0e253a..dc0aeba26 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs @@ -1008,7 +1008,7 @@ impl<'a> DemSamplerBuilder<'a> { let tracked_op_labels: Vec> = circuit .annotations() .iter() - .filter(|a| matches!(a.kind, AnnotationKind::Operator)) + .filter(|a| matches!(a.kind, AnnotationKind::TrackedOperator)) .map(|a| a.label.clone()) .collect(); if !tracked_op_labels.is_empty() { @@ -1516,14 +1516,14 @@ mod tests { } #[test] - fn from_circuit_preserves_pauli_operator_tracked_ops() { + fn from_circuit_preserves_tracked_operator_ops() { use crate::fault_tolerance::dem_builder::NoiseConfig; - use pecos_core::pauli::constructors::X; + use pecos_core::pauli::X; let mut circuit = DagCircuit::new(); circuit.pz(&[0]); circuit.h(&[0]); - circuit.pauli_operator_labeled("x_check", X(0)); + circuit.tracked_operator_labeled("x_check", X(0)); let noise = NoiseConfig::new(0.03, 0.0, 0.0, 0.0); let sampler = DemSampler::from_circuit(&circuit, &noise).unwrap(); @@ -1544,13 +1544,13 @@ mod tests { } #[test] - fn detector_mode_keeps_observables_unshifted_with_pauli_operators() { - use pecos_core::pauli::constructors::X; + fn detector_mode_keeps_observables_unshifted_with_tracked_operators() { + use pecos_core::pauli::X; let mut circuit = DagCircuit::new(); circuit.pz(&[0]); circuit.h(&[0]); - circuit.pauli_operator_labeled("x_check", X(0)); + circuit.tracked_operator_labeled("x_check", X(0)); circuit.mz(&[0]); let im = InfluenceBuilder::new(&circuit) @@ -1622,13 +1622,13 @@ mod tests { #[test] fn from_detector_error_model_preserves_observable_and_tracked_operator_split() { use super::super::builder::DemBuilder; - use pecos_core::pauli::constructors::X; + use pecos_core::pauli::X; use pecos_quantum::Attribute; let mut circuit = DagCircuit::new(); circuit.pz(&[0]); circuit.h(&[0]); - circuit.pauli_operator_labeled("x_check", X(0)); + circuit.tracked_operator_labeled("x_check", X(0)); circuit.mz(&[0]); circuit.set_attr("num_measurements", Attribute::String("1".to_string())); circuit.set_attr( @@ -1675,13 +1675,13 @@ mod tests { #[test] fn observable_mask_ignores_tracked_operator_outputs() { use super::super::builder::DemBuilder; - use pecos_core::pauli::constructors::X; + use pecos_core::pauli::X; use pecos_quantum::Attribute; let mut circuit = DagCircuit::new(); circuit.pz(&[0]); circuit.h(&[0]); - circuit.pauli_operator_labeled("x_check", X(0)); + circuit.tracked_operator_labeled("x_check", X(0)); circuit.mz(&[0]); circuit.set_attr("num_measurements", Attribute::String("1".to_string())); circuit.set_attr( diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs index 58854fc21..1882a4760 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs @@ -1329,7 +1329,7 @@ impl std::error::Error for PecosDemMetadataError {} /// # Examples /// /// ```ignore -/// use pecos_core::pauli::constructors::{X, Y, Z}; +/// use pecos_core::pauli::{X, Y, Z}; /// /// // Single-qubit: biased toward dephasing /// let w = PauliWeights::from([(Z(0), 0.8), (X(0), 0.1), (Y(0), 0.1)]); @@ -1367,7 +1367,7 @@ impl PauliWeights { /// Uniform weights for single-qubit gates: X, Y, Z each with 1/3. #[must_use] pub fn uniform_1q() -> Self { - use pecos_core::pauli::constructors::{X, Y, Z}; + use pecos_core::pauli::{X, Y, Z}; Self { entries: vec![(X(0), 1.0 / 3.0), (Y(0), 1.0 / 3.0), (Z(0), 1.0 / 3.0)], } @@ -1376,7 +1376,7 @@ impl PauliWeights { /// Uniform weights for two-qubit gates: all 15 non-identity Paulis at 1/15. #[must_use] pub fn uniform_2q() -> Self { - use pecos_core::pauli::constructors::{X, Y, Z}; + use pecos_core::pauli::{X, Y, Z}; let w = 1.0 / 15.0; Self { entries: vec![ @@ -1626,7 +1626,7 @@ impl NoiseConfig { /// Sets custom per-Pauli weights for single-qubit gates. /// /// ```ignore - /// use pecos_core::pauli::constructors::{X, Y, Z}; + /// use pecos_core::pauli::{X, Y, Z}; /// noise.set_p1_weights(PauliWeights::from([ /// (X(0), 0.1), (Y(0), 0.1), (Z(0), 0.8), /// ])); @@ -3466,8 +3466,8 @@ mod tests { } #[test] - fn test_pecos_metadata_json_preserves_pauli_operator_ops() { - use pecos_core::pauli::constructors::{X, Z}; + fn test_pecos_metadata_json_preserves_tracked_operator_ops() { + use pecos_core::pauli::{X, Z}; let mut dem = DetectorErrorModel::new(); dem.add_dem_output( @@ -3496,7 +3496,7 @@ mod tests { #[test] fn test_dem_counts_keep_detectors_observables_and_tracked_operators_distinct() { - use pecos_core::pauli::constructors::X; + use pecos_core::pauli::X; let mut dem = DetectorErrorModel::new(); dem.add_detector(DetectorDef::new(0).with_records([-1])); @@ -3520,7 +3520,7 @@ mod tests { #[test] fn test_duplicate_observable_definitions_merge_records_by_parity() { - use pecos_core::pauli::constructors::X; + use pecos_core::pauli::X; let mut dem = DetectorErrorModel::new(); dem.add_observable( @@ -3564,7 +3564,7 @@ mod tests { #[cfg(debug_assertions)] #[should_panic(expected = "conflicting Pauli metadata for observable L0")] fn test_duplicate_observable_definitions_reject_conflicting_paulis() { - use pecos_core::pauli::constructors::{X, Z}; + use pecos_core::pauli::{X, Z}; let mut dem = DetectorErrorModel::new(); dem.add_observable(DemOutput::new(0).with_pauli(X(0))); @@ -3573,7 +3573,7 @@ mod tests { #[test] fn test_dem_output_kind_predicates_are_mutually_exclusive() { - use pecos_core::pauli::constructors::X; + use pecos_core::pauli::X; let observable = DemOutput::new(0) .with_kind(DemOutputKind::Observable) @@ -3621,7 +3621,7 @@ mod tests { #[test] fn test_pecos_metadata_json_round_trips_tracked_operator_metadata() { - use pecos_core::pauli::constructors::{X, Z}; + use pecos_core::pauli::{X, Z}; let mut dem = DetectorErrorModel::new(); dem.add_dem_output(DemOutput::new(0)); @@ -3749,7 +3749,7 @@ mod tests { #[test] fn test_pecos_dem_text_is_stim_superset_with_dem_output_metadata() { - use pecos_core::pauli::constructors::{X, Z}; + use pecos_core::pauli::{X, Z}; let mut dem = DetectorErrorModel::new(); dem.add_detector(DetectorDef::new(0)); @@ -3796,7 +3796,7 @@ mod tests { #[test] fn test_pecos_dem_text_round_trips_observables_and_tracked_ops() { - use pecos_core::pauli::constructors::Z; + use pecos_core::pauli::Z; let mut dem = DetectorErrorModel::new(); dem.add_detector(DetectorDef::new(0)); diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index da43794f8..70ac83b45 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -1289,7 +1289,7 @@ fn parse_observable_records(tc: &TickCircuit) -> Vec> { fn parse_tracked_operator_annotations(tc: &TickCircuit) -> Vec { tc.annotations() .iter() - .filter(|ann| matches!(ann.kind, AnnotationKind::Operator)) + .filter(|ann| matches!(ann.kind, AnnotationKind::TrackedOperator)) .map(|ann| { let mut pauli = ann.pauli.clone(); pauli.set_phase(pecos_core::QuarterPhase::PlusOne); @@ -2647,7 +2647,7 @@ mod tests { fn test_catalog_keeps_observables_and_tracked_ops_distinct() { let mut tc = TickCircuit::new(); tc.tick().h(&[QubitId(0)]); - tc.pauli_operator_labeled("tracked_z0", PauliString::z(0)); + tc.tracked_operator_labeled("tracked_z0", PauliString::z(0)); tc.set_meta( "detectors", pecos_quantum::Attribute::String("[]".to_string()), @@ -2892,7 +2892,7 @@ mod tests { fn test_tracked_only_effect_stays_in_catalog_but_not_raw_mechanisms() { let mut tc = TickCircuit::new(); tc.tick().h(&[QubitId(0)]); - tc.pauli_operator_labeled("tracked_z0", PauliString::z(0)); + tc.tracked_operator_labeled("tracked_z0", PauliString::z(0)); let mut catalog = FaultCatalog::from_circuit(&tc).unwrap(); catalog.with_noise(&StochasticNoiseParams { diff --git a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs index fb381d89c..6c9bb5f07 100644 --- a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs @@ -59,7 +59,7 @@ struct ObservablePropagationWork<'a> { /// |------|---------|---------|-----| /// | Detector | Syndrome parity from measurements | measurement XOR = 0 | `dag.detector(&[...])` | /// | Observable | Standard `L` output from measurements | measurement XOR | `dag.observable(&[...])` | -/// | Tracked operator | User Pauli operator annotated at a circuit point | fault anticommutes with operator | `dag.pauli_operator(&[...])` | +/// | Tracked operator | User Pauli operator annotated at a circuit point | fault anticommutes with operator | `dag.tracked_operator(&[...])` | /// /// Observables and tracked operators both use backward Pauli propagation, but /// they are not the same concept. Observables are values observed through @@ -144,10 +144,10 @@ impl<'a> InfluenceBuilder<'a> { /// /// ```ignore /// // Check if Y = X_0 * Z_1 * Z_2 flips - /// builder.with_pauli_operator(PauliString::from_paulis(vec![(0, 1), (1, 3), (2, 3)])) + /// builder.with_tracked_operator(PauliString::from_paulis(vec![(0, 1), (1, 3), (2, 3)])) /// ``` #[must_use] - pub fn with_pauli_operator(mut self, pauli: PauliString) -> Self { + pub fn with_tracked_operator(mut self, pauli: PauliString) -> Self { self.push_single_term_output(DemOutputMetadata::tracked_operator(pauli), None); self } @@ -169,7 +169,7 @@ impl<'a> InfluenceBuilder<'a> { /// own Z-type propagation term starting at that measurement node. The terms /// accumulate into the same observable `L` output. /// - /// Operator annotations have a corresponding `PauliOperatorMeta` node + /// Tracked-operator annotations have a corresponding `PauliOperatorMeta` node /// that marks their time position. /// /// Detector annotations are NOT handled here -- they are processed @@ -206,7 +206,7 @@ impl<'a> InfluenceBuilder<'a> { terms, }); } - pecos_quantum::AnnotationKind::Operator => { + pecos_quantum::AnnotationKind::TrackedOperator => { let meta_node = meta_nodes.get(operator_idx).copied(); operator_idx += 1; self.push_single_term_output( @@ -1047,7 +1047,7 @@ mod tests { } #[test] - fn test_with_pauli_operator() { + fn test_with_tracked_operator() { let mut dag = DagCircuit::new(); dag.pz(&[2]); dag.cx(&[(0, 2)]); @@ -1077,14 +1077,14 @@ mod tests { #[test] fn test_circuit_annotation_dem_output_metadata_tracks_observables_and_operators() { - use pecos_core::pauli::constructors::X; + use pecos_core::pauli::X; let mut dag = DagCircuit::new(); dag.pz(&[0]); dag.h(&[0]); let meas = dag.mz(&[0]); dag.observable_labeled("record_obs", &[meas[0]]); - dag.pauli_operator_labeled("track_x", X(0)); + dag.tracked_operator_labeled("track_x", X(0)); let map = InfluenceBuilder::new(&dag) .with_circuit_annotations(&dag) diff --git a/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs b/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs index 3ae316d02..fa181284a 100644 --- a/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs +++ b/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs @@ -473,14 +473,14 @@ fn observable_ids(map: &DagFaultInfluenceMap) -> Vec { mod tests { use super::*; use crate::fault_tolerance::InfluenceBuilder; - use pecos_core::pauli::constructors::X; + use pecos_core::pauli::X; use pecos_quantum::DagCircuit; #[test] fn observable_indices_use_compact_l_namespace_with_tracked_ops() { let mut dag = DagCircuit::new(); dag.pz(&[0]); - dag.pauli_operator_labeled("track_x", X(0)); + dag.tracked_operator_labeled("track_x", X(0)); let meas = dag.mz(&[0]); dag.observable_labeled("obs0", &[meas[0]]); diff --git a/crates/pecos-qec/src/stabilizer_code.rs b/crates/pecos-qec/src/stabilizer_code.rs index 61c03795e..98fb30e56 100644 --- a/crates/pecos-qec/src/stabilizer_code.rs +++ b/crates/pecos-qec/src/stabilizer_code.rs @@ -128,7 +128,7 @@ impl StabilizerCode { /// /// ``` /// use pecos_qec::StabilizerCode; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// /// // Repetition code [[3,1]]: logicals are X_L = XXX, Z_L = Z on any qubit /// let code = StabilizerCode::repetition(3); @@ -215,7 +215,7 @@ impl StabilizerCode { /// /// ``` /// use pecos_qec::StabilizerCode; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// /// // Repetition code [[3,1,1]]: distance 1 (logical Z = Z on any single qubit) /// let code = StabilizerCode::repetition(3); @@ -283,7 +283,7 @@ impl StabilizerCode { /// /// ``` /// use pecos_qec::StabilizerCode; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// /// // Repetition code: ZZI, IZZ on 3 qubits /// let code = StabilizerCode::repetition(3); @@ -347,7 +347,7 @@ impl StabilizerCode { /// ``` #[must_use] pub fn repetition(n: usize) -> Self { - use pecos_core::pauli::constructors::Zs; + use pecos_core::pauli::Zs; assert!( n >= 2, "repetition code requires at least 2 qubits, got {n}" @@ -377,7 +377,7 @@ impl StabilizerCode { /// ``` #[must_use] pub fn steane() -> Self { - use pecos_core::pauli::constructors::{Xs, Zs}; + use pecos_core::pauli::{Xs, Zs}; let generators = vec![ Xs([0, 2, 4, 6]), Xs([1, 2, 5, 6]), @@ -411,7 +411,7 @@ impl StabilizerCode { /// ``` #[must_use] pub fn five_qubit() -> Self { - use pecos_core::pauli::constructors::{X, Z}; + use pecos_core::pauli::{X, Z}; let generators = vec![ X(0) & Z(1) & Z(2) & X(3), // XZZXI X(1) & Z(2) & Z(3) & X(4), // IXZZX @@ -441,7 +441,7 @@ impl StabilizerCode { /// ``` #[must_use] pub fn shor() -> Self { - use pecos_core::pauli::constructors::{Xs, Zs}; + use pecos_core::pauli::{Xs, Zs}; let generators = vec![ Xs([0, 1]), Xs([1, 2]), @@ -477,7 +477,7 @@ impl StabilizerCode { /// ``` #[must_use] pub fn four_two_two() -> Self { - use pecos_core::pauli::constructors::{Xs, Zs}; + use pecos_core::pauli::{Xs, Zs}; let generators = vec![Xs([0, 1, 2, 3]), Zs([0, 1, 2, 3])]; Self { group: PauliStabilizerGroup::from_generators_unchecked(generators), @@ -506,7 +506,7 @@ impl StabilizerCode { /// ``` #[must_use] pub fn toric(l: usize) -> Self { - use pecos_core::pauli::constructors::{Xs, Zs}; + use pecos_core::pauli::{Xs, Zs}; assert!(l >= 2, "toric code requires L >= 2, got {l}"); let n = 2 * l * l; @@ -557,7 +557,7 @@ impl StabilizerCode { #[cfg(test)] mod tests { use super::*; - use pecos_core::pauli::constructors::*; + use pecos_core::pauli::*; // ======================================================================== // Basic code parameter tests diff --git a/crates/pecos-qec/src/stabilizer_code_spec.rs b/crates/pecos-qec/src/stabilizer_code_spec.rs index 7c2e4840b..e1d753106 100644 --- a/crates/pecos-qec/src/stabilizer_code_spec.rs +++ b/crates/pecos-qec/src/stabilizer_code_spec.rs @@ -938,10 +938,7 @@ impl StabilizerCodeSpecBuilder { self } - /// Adds a stabilizer from an `UnitaryRep`. - /// - /// The operator must be convertible to a `PauliString` (i.e., a Pauli operator - /// or tensor product of Pauli operators). + /// Adds a stabilizer Pauli operator. /// /// # Example /// @@ -956,18 +953,9 @@ impl StabilizerCodeSpecBuilder { /// .unwrap(); /// ``` /// - /// Accepts both `PauliString` and `UnitaryRep` (via `Into`). - /// - /// # Panics - /// - /// Panics if the operator cannot be converted to a `PauliString`. #[must_use] - pub fn check(mut self, op: impl Into) -> Self { - let ps = op - .into() - .try_to_pauli_string() - .expect("UnitaryRep must be convertible to PauliString"); - self.stabilizers.push(ps); + pub fn check(mut self, op: impl Into) -> Self { + self.stabilizers.push(op.into()); self } @@ -978,20 +966,10 @@ impl StabilizerCodeSpecBuilder { self } - /// Adds a logical Z operator. - /// - /// Accepts both `PauliString` and `UnitaryRep` (via `Into`). - /// - /// # Panics - /// - /// Panics if the operator cannot be converted to a `PauliString`. + /// Adds a logical Z Pauli operator. #[must_use] - pub fn logical_z(mut self, op: impl Into) -> Self { - let ps = op - .into() - .try_to_pauli_string() - .expect("UnitaryRep must be convertible to PauliString"); - self.logical_zs.push(ps); + pub fn logical_z(mut self, op: impl Into) -> Self { + self.logical_zs.push(op.into()); self } @@ -1002,20 +980,10 @@ impl StabilizerCodeSpecBuilder { self } - /// Adds a logical X operator. - /// - /// Accepts both `PauliString` and `UnitaryRep` (via `Into`). - /// - /// # Panics - /// - /// Panics if the operator cannot be converted to a `PauliString`. + /// Adds a logical X Pauli operator. #[must_use] - pub fn logical_x(mut self, op: impl Into) -> Self { - let ps = op - .into() - .try_to_pauli_string() - .expect("UnitaryRep must be convertible to PauliString"); - self.logical_xs.push(ps); + pub fn logical_x(mut self, op: impl Into) -> Self { + self.logical_xs.push(op.into()); self } @@ -1695,7 +1663,7 @@ mod tests { #[test] fn test_stabilizer_group_algebraic_analysis() { - use pecos_core::pauli::constructors::*; + use pecos_core::pauli::*; // Use SurfaceCode and convert for algebraic analysis let surface = crate::SurfaceCode::rotated(3).unwrap(); @@ -1808,7 +1776,7 @@ mod tests { #[test] fn test_from_stabilizer_code_preserves_explicit_num_qubits() { - use pecos_core::pauli::constructors::Z; + use pecos_core::pauli::Z; use pecos_quantum::PauliStabilizerGroup; // StabilizerCode with explicit num_qubits > group touches diff --git a/crates/pecos-qec/tests/fault_enumeration_example.rs b/crates/pecos-qec/tests/fault_enumeration_example.rs index d615d9d42..83edb2498 100644 --- a/crates/pecos-qec/tests/fault_enumeration_example.rs +++ b/crates/pecos-qec/tests/fault_enumeration_example.rs @@ -21,7 +21,7 @@ //! 3. Enumerate fault combinations up to weight 3 //! 4. Classify errors (detectable, undetectable, logical) -use pecos_core::pauli::constructors::X; +use pecos_core::pauli::X; use pecos_qec::fault_tolerance::InfluenceBuilder; use pecos_quantum::DagCircuit; @@ -99,7 +99,7 @@ fn build_repetition_code(num_rounds: usize) -> DagCircuit { dag.observable_labeled("logical_Z", &[ms_data[0]]); // Pauli operator: track logical X = X_0 X_1 X_2 - dag.pauli_operator_labeled("logical_X", X(0) & X(1) & X(2)); + dag.tracked_operator_labeled("logical_X", X(0) & X(1) & X(2)); dag } @@ -114,7 +114,7 @@ fn repetition_code_fault_enumeration() { let kind = match &ann.kind { pecos_quantum::AnnotationKind::Detector { .. } => "detector", pecos_quantum::AnnotationKind::Observable { .. } => "observable", - pecos_quantum::AnnotationKind::Operator => "operator", + pecos_quantum::AnnotationKind::TrackedOperator => "tracked_operator", }; let label = ann.label.as_deref().unwrap_or("(none)"); println!(" {kind:10} {label:15} {}", ann.pauli); @@ -610,9 +610,9 @@ fn build_422_code(num_rounds: usize) -> DagCircuit { // Pauli operators: logical X operators // Logical X_1 = X_0 X_2 - dag.pauli_operator_labeled("logical_X1", X(0) & X(2)); + dag.tracked_operator_labeled("logical_X1", X(0) & X(2)); // Logical X_2 = X_0 X_1 - dag.pauli_operator_labeled("logical_X2", X(0) & X(1)); + dag.tracked_operator_labeled("logical_X2", X(0) & X(1)); dag } @@ -628,7 +628,7 @@ fn code_422_fault_enumeration() { let kind = match &ann.kind { pecos_quantum::AnnotationKind::Detector { .. } => "detector", pecos_quantum::AnnotationKind::Observable { .. } => "observable", - pecos_quantum::AnnotationKind::Operator => "operator", + pecos_quantum::AnnotationKind::TrackedOperator => "tracked_operator", }; let label = ann.label.as_deref().unwrap_or("(none)"); println!(" {kind:10} {label:15} {}", ann.pauli); diff --git a/crates/pecos-qec/tests/targeted_tests.rs b/crates/pecos-qec/tests/targeted_tests.rs index 84b16df87..4cd32bd7f 100644 --- a/crates/pecos-qec/tests/targeted_tests.rs +++ b/crates/pecos-qec/tests/targeted_tests.rs @@ -12,7 +12,7 @@ //! Targeted tests for specific features and bug fixes from the annotation/decoder session. -use pecos_core::pauli::constructors::{X, Y, Z}; +use pecos_core::pauli::{X, Y, Z}; use pecos_qec::fault_tolerance::InfluenceBuilder; use pecos_qec::fault_tolerance::dem_builder::{NoiseConfig, PauliWeights}; use pecos_qec::fault_tolerance::lookup_decoder::LookupDecoder; @@ -283,9 +283,9 @@ fn detector_derives_pauli_from_measurements() { assert_eq!(paulis[1].0, pecos_core::Pauli::Z); } -/// Verify `pauli_operator` normalizes phase to +1. +/// Verify `tracked_operator` normalizes phase to +1. #[test] -fn pauli_operator_normalizes_phase() { +fn tracked_operator_normalizes_phase() { let mut dag = DagCircuit::new(); dag.pz(&[0]); @@ -293,7 +293,7 @@ fn pauli_operator_normalizes_phase() { let neg_x = -X(0); assert_ne!(neg_x.get_phase(), pecos_core::QuarterPhase::PlusOne); - dag.pauli_operator(neg_x); + dag.tracked_operator(neg_x); // After storage, phase should be normalized to +1 let ann = &dag.annotations()[0]; diff --git a/crates/pecos-quantum/examples/style_demo.rs b/crates/pecos-quantum/examples/style_demo.rs index c3e1b79f7..64703f4cf 100644 --- a/crates/pecos-quantum/examples/style_demo.rs +++ b/crates/pecos-quantum/examples/style_demo.rs @@ -482,7 +482,7 @@ fn main() { // -- UnitaryRep example -- html.push_str("

    UnitaryRep Algebra

    \n"); { - use pecos_core::unitary_rep::{CX, H, T}; + use pecos_core::unitary::{CX, H, T}; let circuit = T(1) * CX(0, 1) * H(0); let op_renderer = circuit.render_with(2, &default_style); write!( diff --git a/crates/pecos-quantum/src/dag_circuit.rs b/crates/pecos-quantum/src/dag_circuit.rs index fe281d7a7..8f5b9e657 100644 --- a/crates/pecos-quantum/src/dag_circuit.rs +++ b/crates/pecos-quantum/src/dag_circuit.rs @@ -390,9 +390,9 @@ pub enum AnnotationKind { /// Logical observable: the Pauli's flip determines a logical outcome. /// Stores measurement node indices for classical readout via XOR. Observable { measurement_nodes: Vec }, - /// Tracked Pauli operator: no measurement readout. + /// Tracked operator: no measurement readout. /// Position is determined by a `PauliOperatorMeta` node in the DAG. - Operator, + TrackedOperator, } /// A unified Pauli annotation: detectors, observables, and tracked operators @@ -402,7 +402,7 @@ pub enum AnnotationKind { /// Their Pauli is Z on the measured qubits. /// - **Observables** are logical operators read out via measurements. /// Their Pauli is Z on the measured qubits. -/// - **Operators** are arbitrary Pauli strings with no measurement readout. +/// - **Tracked operators** are arbitrary Pauli strings with no measurement readout. /// Their Pauli is user-specified and their position comes from a meta-gate node. #[derive(Debug, Clone)] pub struct PauliAnnotation { @@ -1718,10 +1718,10 @@ impl DagCircuit { pecos_core::PauliString::zs(&qubits) } - /// Place a Pauli operator meta-gate at this point in the circuit. + /// Place a tracked-operator meta-gate at this point in the circuit. /// /// This is a **positional** annotation: only faults BEFORE this node - /// can flip the operator. The meta-gate does not affect quantum state + /// can flip the tracked operator. The meta-gate does not affect quantum state /// -- simulators ignore it. /// /// Accepts a [`PauliString`](pecos_core::PauliString), which supports @@ -1732,30 +1732,30 @@ impl DagCircuit { /// # Example /// ``` /// use pecos_quantum::DagCircuit; - /// use pecos_core::pauli::constructors::{X, Z}; + /// use pecos_core::pauli::{X, Z}; /// /// let mut c = DagCircuit::new(); /// c.pz(&[0, 1, 2]); /// c.cx(&[(0, 1)]); /// // Place X_0 & Z_1 & Z_2 check HERE -- only faults above can flip it - /// c.pauli_operator(X(0) & Z(1) & Z(2)); + /// c.tracked_operator(X(0) & Z(1) & Z(2)); /// c.cx(&[(1, 2)]); // faults here don't affect the check /// ``` - pub fn pauli_operator(&mut self, mut pauli: pecos_core::PauliString) -> usize { + pub fn tracked_operator(&mut self, mut pauli: pecos_core::PauliString) -> usize { // Phase is irrelevant for flip tracking -- normalize to +1 pauli.set_phase(pecos_core::QuarterPhase::PlusOne); let idx = self.annotations.len(); self.insert_pauli_meta_gate(&pauli); self.annotations.push(PauliAnnotation { pauli, - kind: AnnotationKind::Operator, + kind: AnnotationKind::TrackedOperator, label: None, }); idx } - /// Place a labeled Pauli operator meta-gate. - pub fn pauli_operator_labeled( + /// Place a labeled tracked-operator meta-gate. + pub fn tracked_operator_labeled( &mut self, label: &str, mut pauli: pecos_core::PauliString, @@ -1765,7 +1765,7 @@ impl DagCircuit { self.insert_pauli_meta_gate(&pauli); self.annotations.push(PauliAnnotation { pauli, - kind: AnnotationKind::Operator, + kind: AnnotationKind::TrackedOperator, label: Some(label.to_string()), }); idx @@ -1786,8 +1786,8 @@ impl DagCircuit { /// Add a pre-built annotation (used for conversion from `TickCircuit`). pub fn add_annotation(&mut self, ann: PauliAnnotation) { - // For Operator annotations, insert the meta-gate node - if matches!(ann.kind, AnnotationKind::Operator) { + // For tracked-operator annotations, insert the meta-gate node. + if matches!(ann.kind, AnnotationKind::TrackedOperator) { self.insert_pauli_meta_gate(&ann.pauli); } self.annotations.push(ann); @@ -1807,11 +1807,11 @@ impl DagCircuit { .filter(|a| matches!(a.kind, AnnotationKind::Observable { .. })) } - /// Get tracked Pauli operator annotations. - pub fn pauli_operators(&self) -> impl Iterator { + /// Get tracked-operator annotations. + pub fn tracked_operators(&self) -> impl Iterator { self.annotations .iter() - .filter(|a| matches!(a.kind, AnnotationKind::Operator)) + .filter(|a| matches!(a.kind, AnnotationKind::TrackedOperator)) } // ======================================================================== diff --git a/crates/pecos-quantum/src/operator_matrix.rs b/crates/pecos-quantum/src/operator_matrix.rs deleted file mode 100644 index 033e20019..000000000 --- a/crates/pecos-quantum/src/operator_matrix.rs +++ /dev/null @@ -1,1253 +0,0 @@ -// Copyright 2025 The PECOS Developers -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -//! Matrix representations and operations for quantum operators. -//! -//! This module provides functions to convert operators to dense matrices -//! and perform matrix-level operations like exponential and logarithm. -//! -//! # Extension Trait -//! -//! The [`ToMatrix`] trait provides a method-style API for converting operators: -//! -//! ``` -//! use pecos_quantum::operator_matrix::ToMatrix; -//! use pecos_core::operator::X; -//! -//! let x = X(0); -//! let matrix = x.to_matrix(); // Method style -//! ``` - -use nalgebra::DMatrix; -use num_complex::Complex64; -use pecos_core::gate_type::GateType; -use pecos_core::operator::{Operator, RotationType}; -use pecos_core::{Pauli, PauliString, Phase}; - -/// Extension trait for converting quantum operators to matrix representations. -/// -/// This trait is implemented for [`Operator`] and [`PauliString`], providing -/// a method-style API for matrix conversion. -/// -/// # Example -/// -/// ``` -/// use pecos_quantum::operator_matrix::ToMatrix; -/// use pecos_core::operator::{X, H, CX, Is}; -/// -/// // Single qubit gate -/// let x_matrix = X(0).to_matrix(); -/// assert_eq!(x_matrix.nrows(), 2); -/// -/// // Two qubit gate -/// let cnot_matrix = CX(0, 1).to_matrix(); -/// assert_eq!(cnot_matrix.nrows(), 4); -/// -/// // For larger matrices, tensor with identities using Is() -/// let x_extended = X(0) & Is(1..3); // X on qubit 0 in 3-qubit space -/// let mat = x_extended.to_matrix(); -/// assert_eq!(mat.nrows(), 8); -/// ``` -pub trait ToMatrix { - /// Converts to a dense matrix representation. - /// - /// The matrix size is 2^n where n is determined by the maximum qubit index + 1. - fn to_matrix(&self) -> DMatrix; -} - -impl ToMatrix for Operator { - fn to_matrix(&self) -> DMatrix { - to_matrix(self) - } -} - -impl ToMatrix for PauliString { - fn to_matrix(&self) -> DMatrix { - let num_qubits = self.qubits().into_iter().max().map_or(1, |q| q + 1); - pauli_string_to_matrix_impl(self, num_qubits) - } -} - -/// Converts an `Operator` to its dense matrix representation. -/// -/// The matrix size is 2^n where n is the number of qubits (determined by -/// the maximum qubit index + 1). -/// -/// # Example -/// -/// ``` -/// use pecos_quantum::operator_matrix::to_matrix; -/// use pecos_core::operator::X; -/// use num_complex::Complex64; -/// -/// let x = X(0); -/// let matrix = to_matrix(&x); -/// -/// // X gate matrix: [[0, 1], [1, 0]] -/// assert_eq!(matrix.nrows(), 2); -/// assert!((matrix[(0, 1)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); -/// ``` -#[must_use] -pub fn to_matrix(op: &Operator) -> DMatrix { - let num_qubits = op.qubits().into_iter().max().map_or(1, |q| q + 1); - to_matrix_with_size(op, num_qubits) -} - -/// Converts an `Operator` to its dense matrix representation with a specified size. -/// -/// # Arguments -/// * `op` - The operator to convert -/// * `num_qubits` - The number of qubits (matrix will be `2^num_qubits` x `2^num_qubits`) -#[must_use] -pub fn to_matrix_with_size(op: &Operator, num_qubits: usize) -> DMatrix { - let dim = 1 << num_qubits; // 2^num_qubits - - match op { - Operator::Pauli(ps) => pauli_string_to_matrix_impl(ps, num_qubits), - - Operator::Rotation { - rotation_type, - angle, - qubits, - } => rotation_to_matrix(*rotation_type, angle.to_radians(), qubits, num_qubits), - - Operator::Gate { gate_type, qubits } => gate_to_matrix(*gate_type, qubits, num_qubits), - - Operator::Tensor(parts) => { - // Start with identity, combine each part - let mut result = DMatrix::identity(dim, dim); - for part in parts { - let part_matrix = to_matrix_with_size(part, num_qubits); - result = combine_disjoint_operators(&result, &part_matrix); - } - result - } - - Operator::Compose(parts) => { - // Matrix multiplication in reverse order (last part applied first) - let mut result = DMatrix::identity(dim, dim); - for part in parts { - let part_matrix = to_matrix_with_size(part, num_qubits); - result = part_matrix * result; - } - result - } - - Operator::Adjoint(inner) => { - let inner_matrix = to_matrix_with_size(inner, num_qubits); - inner_matrix.adjoint() - } - - Operator::Phase { phase, inner } => { - let inner_matrix = to_matrix_with_size(inner, num_qubits); - let phase_factor = Complex64::new(0.0, phase.to_radians()).exp(); - inner_matrix * phase_factor - } - } -} - -/// Computes the matrix exponential of an operator: exp(i * op). -/// -/// This is useful for generating unitaries from Hermitian generators. -/// -/// # Example -/// -/// ``` -/// use pecos_quantum::operator_matrix::operator_exp; -/// use pecos_core::operator::Z; -/// use num_complex::Complex64; -/// use std::f64::consts::PI; -/// -/// // exp(i * pi * Z) = -I -/// let z = Z(0); -/// let result = operator_exp(&z, PI); -/// // Result should be approximately -I -/// ``` -#[must_use] -pub fn operator_exp(op: &Operator, theta: f64) -> DMatrix { - let matrix = to_matrix(op); - let scaled = matrix * Complex64::new(0.0, theta); - pecos_num::matrix_exp(&scaled) -} - -/// Computes the matrix logarithm of an operator. -/// -/// Returns `Some(generator)` where `exp(i * generator) = op`, or `None` if -/// the computation fails (e.g., for singular matrices). -/// -/// # Example -/// -/// ``` -/// use pecos_quantum::operator_matrix::{operator_log, to_matrix}; -/// use pecos_core::operator::X; -/// -/// let x = X(0); -/// if let Some(log_x) = operator_log(&x) { -/// // log_x is the generator such that exp(i * log_x) = X -/// } -/// ``` -#[must_use] -pub fn operator_log(op: &Operator) -> Option> { - let matrix = to_matrix(op); - let log_matrix = pecos_num::matrix_log(&matrix)?; - // Divide by i to get the Hermitian generator - Some(log_matrix / Complex64::new(0.0, 1.0)) -} - -/// Checks if two operators are equivalent up to a global phase. -/// -/// Returns `true` if A = e^{i*phi} * B for some real phi. -/// -/// # Example -/// -/// ``` -/// use pecos_quantum::operator_matrix::operators_equiv; -/// use pecos_core::operator::{X, Y, Z}; -/// -/// let x = X(0); -/// let x2 = X(0); -/// assert!(operators_equiv(&x, &x2)); -/// -/// let y = Y(0); -/// assert!(!operators_equiv(&x, &y)); -/// ``` -#[must_use] -pub fn operators_equiv(a: &Operator, b: &Operator) -> bool { - operators_equiv_with_tolerance(a, b, 1e-10) -} - -/// Checks if two operators are equivalent up to a global phase, with custom tolerance. -#[must_use] -pub fn operators_equiv_with_tolerance(a: &Operator, b: &Operator, tol: f64) -> bool { - let num_qubits_a = a.qubits().into_iter().max().map_or(1, |q| q + 1); - let num_qubits_b = b.qubits().into_iter().max().map_or(1, |q| q + 1); - let num_qubits = num_qubits_a.max(num_qubits_b); - - let mat_a = to_matrix_with_size(a, num_qubits); - let mat_b = to_matrix_with_size(b, num_qubits); - - matrices_equiv_up_to_phase(&mat_a, &mat_b, tol) -} - -/// Checks if two matrices are equal up to a global phase factor. -fn matrices_equiv_up_to_phase(a: &DMatrix, b: &DMatrix, tol: f64) -> bool { - if a.nrows() != b.nrows() || a.ncols() != b.ncols() { - return false; - } - - // Find the first non-zero element to determine the phase - let mut phase: Option = None; - - for i in 0..a.nrows() { - for j in 0..a.ncols() { - let a_val = a[(i, j)]; - let b_val = b[(i, j)]; - - // Skip near-zero elements - if a_val.norm() < tol && b_val.norm() < tol { - continue; - } - - // If one is zero but not the other, not equivalent - if a_val.norm() < tol || b_val.norm() < tol { - return false; - } - - // Compute the ratio a/b - let ratio = a_val / b_val; - - match phase { - None => { - // First non-zero element sets the phase - phase = Some(ratio); - } - Some(p) => { - // Check if this ratio matches the established phase - if (ratio - p).norm() > tol { - return false; - } - } - } - } - } - - // Also verify the phase has unit magnitude (global phase factor) - if let Some(p) = phase { - (p.norm() - 1.0).abs() < tol - } else { - // Both matrices are zero - true - } -} - -// --- Helper functions for matrix construction --- - -/// Converts a [`PauliString`] to a dense matrix (implementation). -fn pauli_string_to_matrix_impl(ps: &PauliString, num_qubits: usize) -> DMatrix { - let dim = 1 << num_qubits; - let mut result = DMatrix::identity(dim, dim); - - // Get the phase - let phase = ps.phase().to_complex(); - - // Apply each single-qubit Pauli - for (pauli, qubit) in ps.iter_pairs() { - let q = usize::from(qubit); - let pauli_matrix = single_pauli_matrix(pauli); - let full_matrix = embed_single_qubit_gate(&pauli_matrix, q, num_qubits); - result = full_matrix * result; - } - - result * phase -} - -/// Returns the 2x2 matrix for a single Pauli operator. -fn single_pauli_matrix(pauli: Pauli) -> DMatrix { - let zero = Complex64::new(0.0, 0.0); - let one = Complex64::new(1.0, 0.0); - let i = Complex64::new(0.0, 1.0); - let neg_i = Complex64::new(0.0, -1.0); - let neg_one = Complex64::new(-1.0, 0.0); - - match pauli { - Pauli::I => DMatrix::from_row_slice(2, 2, &[one, zero, zero, one]), - Pauli::X => DMatrix::from_row_slice(2, 2, &[zero, one, one, zero]), - Pauli::Y => DMatrix::from_row_slice(2, 2, &[zero, neg_i, i, zero]), - Pauli::Z => DMatrix::from_row_slice(2, 2, &[one, zero, zero, neg_one]), - } -} - -/// Embeds a single-qubit gate into a larger Hilbert space. -fn embed_single_qubit_gate( - gate: &DMatrix, - qubit: usize, - num_qubits: usize, -) -> DMatrix { - let dim = 1 << num_qubits; - let mut result = DMatrix::from_element(dim, dim, Complex64::new(0.0, 0.0)); - - for i in 0..dim { - for j in 0..dim { - // Check if all qubits except `qubit` match - let mask = !(1 << qubit); - if (i & mask) == (j & mask) { - let i_bit = (i >> qubit) & 1; - let j_bit = (j >> qubit) & 1; - result[(i, j)] = gate[(i_bit, j_bit)]; - } - } - } - - result -} - -/// Converts a rotation to a matrix. -fn rotation_to_matrix( - rotation_type: RotationType, - angle: f64, - qubits: &[usize], - num_qubits: usize, -) -> DMatrix { - let half_angle = angle / 2.0; - let cos_half = Complex64::new(half_angle.cos(), 0.0); - let sin_half = Complex64::new(half_angle.sin(), 0.0); - let i = Complex64::new(0.0, 1.0); - let neg_i = Complex64::new(0.0, -1.0); - - match rotation_type { - RotationType::RX => { - // RX(θ) = cos(θ/2)I - i*sin(θ/2)X - let gate = DMatrix::from_row_slice( - 2, - 2, - &[cos_half, neg_i * sin_half, neg_i * sin_half, cos_half], - ); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - RotationType::RY => { - // RY(θ) = cos(θ/2)I - i*sin(θ/2)Y - let gate = DMatrix::from_row_slice(2, 2, &[cos_half, -sin_half, sin_half, cos_half]); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - RotationType::RZ => { - // RZ(θ) = cos(θ/2)I - i*sin(θ/2)Z = diag(e^{-iθ/2}, e^{iθ/2}) - let exp_neg = (neg_i * Complex64::new(half_angle, 0.0)).exp(); - let exp_pos = (i * Complex64::new(half_angle, 0.0)).exp(); - let zero = Complex64::new(0.0, 0.0); - let gate = DMatrix::from_row_slice(2, 2, &[exp_neg, zero, zero, exp_pos]); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - RotationType::RXX | RotationType::RYY | RotationType::RZZ => { - // For two-qubit rotations, use matrix exponential - let dim = 1 << num_qubits; - let generator = match rotation_type { - RotationType::RXX => { - two_qubit_pauli_matrix(Pauli::X, Pauli::X, qubits[0], qubits[1], num_qubits) - } - RotationType::RYY => { - two_qubit_pauli_matrix(Pauli::Y, Pauli::Y, qubits[0], qubits[1], num_qubits) - } - RotationType::RZZ => { - two_qubit_pauli_matrix(Pauli::Z, Pauli::Z, qubits[0], qubits[1], num_qubits) - } - _ => DMatrix::identity(dim, dim), - }; - let scaled = generator * Complex64::new(0.0, -half_angle); - pecos_num::matrix_exp(&scaled) - } - } -} - -/// Constructs a two-qubit Pauli tensor product matrix. -fn two_qubit_pauli_matrix( - p1: Pauli, - p2: Pauli, - q1: usize, - q2: usize, - num_qubits: usize, -) -> DMatrix { - let m1 = single_pauli_matrix(p1); - let m2 = single_pauli_matrix(p2); - let e1 = embed_single_qubit_gate(&m1, q1, num_qubits); - let e2 = embed_single_qubit_gate(&m2, q2, num_qubits); - e1 * e2 -} - -/// Converts a gate type to a matrix. -fn gate_to_matrix(gate_type: GateType, qubits: &[usize], num_qubits: usize) -> DMatrix { - let zero = Complex64::new(0.0, 0.0); - let one = Complex64::new(1.0, 0.0); - let i = Complex64::new(0.0, 1.0); - let neg_i = Complex64::new(0.0, -1.0); - let neg_one = Complex64::new(-1.0, 0.0); - let sqrt2_inv = Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0); - - match gate_type { - GateType::I => { - let gate = DMatrix::from_row_slice(2, 2, &[one, zero, zero, one]); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - GateType::X => { - let gate = DMatrix::from_row_slice(2, 2, &[zero, one, one, zero]); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - GateType::Y => { - let gate = DMatrix::from_row_slice(2, 2, &[zero, neg_i, i, zero]); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - GateType::Z => { - let gate = DMatrix::from_row_slice(2, 2, &[one, zero, zero, neg_one]); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - GateType::H => { - let gate = - DMatrix::from_row_slice(2, 2, &[sqrt2_inv, sqrt2_inv, sqrt2_inv, -sqrt2_inv]); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - GateType::SX => { - // SX = (1+i)/2 * [[1, -i], [-i, 1]] - let factor = Complex64::new(0.5, 0.5); - let gate = DMatrix::from_row_slice( - 2, - 2, - &[factor * one, factor * neg_i, factor * neg_i, factor * one], - ); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - GateType::SXdg => { - let factor = Complex64::new(0.5, -0.5); - let gate = DMatrix::from_row_slice( - 2, - 2, - &[factor * one, factor * i, factor * i, factor * one], - ); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - GateType::SZ => { - // S = diag(1, i) - let gate = DMatrix::from_row_slice(2, 2, &[one, zero, zero, i]); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - GateType::SZdg => { - let gate = DMatrix::from_row_slice(2, 2, &[one, zero, zero, neg_i]); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - GateType::T => { - // T = diag(1, e^{i*pi/4}) - let exp_pi_4 = Complex64::from_polar(1.0, std::f64::consts::FRAC_PI_4); - let gate = DMatrix::from_row_slice(2, 2, &[one, zero, zero, exp_pi_4]); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - GateType::Tdg => { - let exp_neg_pi_4 = Complex64::from_polar(1.0, -std::f64::consts::FRAC_PI_4); - let gate = DMatrix::from_row_slice(2, 2, &[one, zero, zero, exp_neg_pi_4]); - embed_single_qubit_gate(&gate, qubits[0], num_qubits) - } - GateType::CX => controlled_gate( - &single_pauli_matrix(Pauli::X), - qubits[0], - qubits[1], - num_qubits, - ), - GateType::CY => controlled_gate( - &single_pauli_matrix(Pauli::Y), - qubits[0], - qubits[1], - num_qubits, - ), - GateType::CZ => controlled_gate( - &single_pauli_matrix(Pauli::Z), - qubits[0], - qubits[1], - num_qubits, - ), - GateType::SWAP => swap_matrix(qubits[0], qubits[1], num_qubits), - _ => { - // Gates not yet implemented: SY, SYdg, U, R1XY, SZZ, SZZdg, CRZ, CCX - // Rotation gates (RX, RY, RZ, RXX, RYY, RZZ) should use Operator::Rotation - // Prep/Measure gates are not unitary and shouldn't be converted to matrices - log::warn!("Gate type {gate_type:?} not implemented in to_matrix, returning identity"); - let dim = 1 << num_qubits; - DMatrix::identity(dim, dim) - } - } -} - -/// Constructs a controlled gate matrix. -fn controlled_gate( - target_gate: &DMatrix, - control: usize, - target: usize, - num_qubits: usize, -) -> DMatrix { - let dim = 1 << num_qubits; - let mut result = DMatrix::identity(dim, dim); - - for i in 0..dim { - for j in 0..dim { - // Only apply gate when control qubit is 1 - let control_bit_i = (i >> control) & 1; - let control_bit_j = (j >> control) & 1; - - if control_bit_i == 1 && control_bit_j == 1 { - // Check if all qubits except target match - let mask = !(1 << target); - if (i & mask) == (j & mask) { - let i_bit = (i >> target) & 1; - let j_bit = (j >> target) & 1; - result[(i, j)] = target_gate[(i_bit, j_bit)]; - } else { - result[(i, j)] = Complex64::new(0.0, 0.0); - } - } else if control_bit_i == control_bit_j && i == j { - result[(i, j)] = Complex64::new(1.0, 0.0); - } else if control_bit_i != control_bit_j { - result[(i, j)] = Complex64::new(0.0, 0.0); - } - } - } - - result -} - -/// Constructs a SWAP gate matrix. -fn swap_matrix(q1: usize, q2: usize, num_qubits: usize) -> DMatrix { - let dim = 1 << num_qubits; - let mut result = DMatrix::from_element(dim, dim, Complex64::new(0.0, 0.0)); - - for i in 0..dim { - // Swap bits at positions q1 and q2 - let bit1 = (i >> q1) & 1; - let bit2 = (i >> q2) & 1; - - let j = if bit1 == bit2 { - i - } else { - // Swap the bits - i ^ (1 << q1) ^ (1 << q2) - }; - - result[(i, j)] = Complex64::new(1.0, 0.0); - } - - result -} - -/// Combines two matrices representing operators on disjoint qubits. -/// -/// When operators act on disjoint qubits, the tensor product in the full Hilbert space -/// is equivalent to matrix multiplication (since disjoint operators commute). -fn combine_disjoint_operators( - a: &DMatrix, - b: &DMatrix, -) -> DMatrix { - a * b -} - -#[cfg(test)] -mod tests { - use super::*; - use pecos_core::Angle64; - use pecos_core::operator::{CX, H, I, Is, RX, RZ, SWAP, SZ, T, X, Y, Z}; - use std::f64::consts::PI; - - // --- Basic to_matrix tests --- - - #[test] - fn test_pauli_matrices() { - let x = X(0); - let mat = to_matrix(&x); - assert_eq!(mat.nrows(), 2); - assert!((mat[(0, 1)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(1, 0)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - - let z = Z(0); - let mat = to_matrix(&z); - assert!((mat[(0, 0)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(1, 1)] - Complex64::new(-1.0, 0.0)).norm() < 1e-10); - } - - #[test] - fn test_pauli_y() { - let y = Y(0); - let mat = to_matrix(&y); - let i = Complex64::new(0.0, 1.0); - assert!((mat[(0, 1)] - (-i)).norm() < 1e-10); - assert!((mat[(1, 0)] - i).norm() < 1e-10); - } - - #[test] - fn test_hadamard() { - let h = H(0); - let mat = to_matrix(&h); - let sqrt2_inv = 1.0 / 2.0_f64.sqrt(); - assert!((mat[(0, 0)] - Complex64::new(sqrt2_inv, 0.0)).norm() < 1e-10); - assert!((mat[(0, 1)] - Complex64::new(sqrt2_inv, 0.0)).norm() < 1e-10); - assert!((mat[(1, 0)] - Complex64::new(sqrt2_inv, 0.0)).norm() < 1e-10); - assert!((mat[(1, 1)] - Complex64::new(-sqrt2_inv, 0.0)).norm() < 1e-10); - } - - #[test] - fn test_cnot() { - let cx = CX(0, 1); - let mat = to_matrix(&cx); - assert_eq!(mat.nrows(), 4); - // CX with control=0, target=1 - // |q1 q0> indexing: index = q1*2 + q0 - // When q0=0 (control off): do nothing - // When q0=1 (control on): flip q1 - // |00> -> |00> (mat[0,0] = 1) - // |01> -> |11> (mat[3,1] = 1) - // |10> -> |10> (mat[2,2] = 1) - // |11> -> |01> (mat[1,3] = 1) - assert!((mat[(0, 0)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(3, 1)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(2, 2)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(1, 3)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - } - - #[test] - fn test_identity() { - let id = I(0); - let mat = to_matrix(&id); - assert!((mat[(0, 0)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(1, 1)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!(mat[(0, 1)].norm() < 1e-10); - assert!(mat[(1, 0)].norm() < 1e-10); - } - - // --- Rotation matrix tests --- - - #[test] - fn test_t_gate_matrix() { - let t = T(0); - let mat = to_matrix(&t); - // T = RZ(π/4) = diag(e^{-iπ/8}, e^{iπ/8}) - let exp_neg = Complex64::from_polar(1.0, -PI / 8.0); - let exp_pos = Complex64::from_polar(1.0, PI / 8.0); - assert!((mat[(0, 0)] - exp_neg).norm() < 1e-10); - assert!((mat[(1, 1)] - exp_pos).norm() < 1e-10); - } - - #[test] - fn test_s_gate_matrix() { - let s = SZ(0); - let mat = to_matrix(&s); - // S = RZ(π/2) = diag(e^{-iπ/4}, e^{iπ/4}) - let exp_neg = Complex64::from_polar(1.0, -PI / 4.0); - let exp_pos = Complex64::from_polar(1.0, PI / 4.0); - assert!((mat[(0, 0)] - exp_neg).norm() < 1e-10); - assert!((mat[(1, 1)] - exp_pos).norm() < 1e-10); - } - - #[test] - fn test_rx_matrix() { - // RX(π) should give X (up to global phase) - let rx_pi = RX(Angle64::HALF_TURN, 0); - let mat = to_matrix(&rx_pi); - let x_mat = to_matrix(&X(0)); - // RX(π) = -iX, so matrices differ by global phase -i - assert!(matrices_equiv_up_to_phase(&mat, &x_mat, 1e-10)); - } - - #[test] - fn test_rz_matrix() { - // RZ(π) should give Z (up to global phase) - let rz_pi = RZ(Angle64::HALF_TURN, 0); - let mat = to_matrix(&rz_pi); - let z_mat = to_matrix(&Z(0)); - assert!(matrices_equiv_up_to_phase(&mat, &z_mat, 1e-10)); - } - - // --- Tensor product and composition tests --- - - #[test] - fn test_tensor_product() { - // X ⊗ Z should give a 4x4 matrix - let xz = X(0) & Z(1); - let mat = to_matrix(&xz); - assert_eq!(mat.nrows(), 4); - - // Verify it's the product of embedded X and Z - let x_embedded = to_matrix_with_size(&X(0), 2); - let z_embedded = to_matrix_with_size(&Z(1), 2); - let expected = &x_embedded * &z_embedded; - assert!(matrices_equiv_up_to_phase(&mat, &expected, 1e-10)); - } - - #[test] - fn test_composition() { - // H * X = XH (matrix multiplication order) - let hx = H(0) * X(0); - let mat = to_matrix(&hx); - - let h_mat = to_matrix(&H(0)); - let x_mat = to_matrix(&X(0)); - let expected = &h_mat * &x_mat; - assert!(matrices_equiv_up_to_phase(&mat, &expected, 1e-10)); - } - - #[test] - fn test_adjoint_matrix() { - // T† matrix should be conjugate transpose of T - let t = T(0); - let t_dg = t.dg(); - let mat_t = to_matrix(&t); - let mat_t_dg = to_matrix(&t_dg); - - let expected = mat_t.adjoint(); - assert!(matrices_equiv_up_to_phase(&mat_t_dg, &expected, 1e-10)); - } - - #[test] - fn test_swap_gate() { - let swap = SWAP(0, 1); - let mat = to_matrix(&swap); - assert_eq!(mat.nrows(), 4); - - // SWAP|00> = |00>, SWAP|01> = |10>, SWAP|10> = |01>, SWAP|11> = |11> - assert!((mat[(0, 0)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(2, 1)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(1, 2)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(3, 3)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - } - - // --- operators_equiv tests --- - - #[test] - fn test_operators_equiv_same() { - let x1 = X(0); - let x2 = X(0); - assert!(operators_equiv(&x1, &x2)); - } - - #[test] - fn test_operators_equiv_different() { - let x = X(0); - let y = Y(0); - assert!(!operators_equiv(&x, &y)); - } - - #[test] - fn test_operators_equiv_global_phase() { - // X and -X differ by global phase -1 - let x = X(0); - let neg_x = pecos_core::operator::phase(Angle64::HALF_TURN) * X(0); - assert!(operators_equiv(&x, &neg_x)); - } - - #[test] - fn test_operators_equiv_i_phase() { - // X and iX differ by global phase i - let x = X(0); - let i_x = pecos_core::operator::i * X(0); - assert!(operators_equiv(&x, &i_x)); - } - - // --- operator_exp tests --- - - #[test] - fn test_operator_exp_identity() { - // exp(i * 0 * X) = I - let x = X(0); - let result = operator_exp(&x, 0.0); - let identity = DMatrix::identity(2, 2); - assert!(matrices_equiv_up_to_phase(&result, &identity, 1e-10)); - } - - #[test] - fn test_operator_exp_pauli_pi() { - // exp(i * π * Z) = -I - let z = Z(0); - let result = operator_exp(&z, PI); - let neg_identity: DMatrix = DMatrix::identity(2, 2) * Complex64::new(-1.0, 0.0); - assert!(matrices_equiv_up_to_phase(&result, &neg_identity, 1e-10)); - } - - #[test] - fn test_operator_exp_pauli_half_pi() { - // exp(i * π/2 * X) = i*X = [[0, i], [i, 0]] - let x = X(0); - let result = operator_exp(&x, PI / 2.0); - let i = Complex64::new(0.0, 1.0); - let expected = to_matrix(&x) * i; - assert!(matrices_equiv_up_to_phase(&result, &expected, 1e-10)); - } - - // --- operator_log tests --- - - #[test] - fn test_operator_log_identity() { - // log(I) = 0 - let id = I(0); - let result = operator_log(&id); - assert!(result.is_some()); - let log_mat = result.unwrap(); - // All elements should be near zero - for i in 0..log_mat.nrows() { - for j in 0..log_mat.ncols() { - assert!(log_mat[(i, j)].norm() < 1e-8); - } - } - } - - #[test] - fn test_operator_log_returns_matrix() { - // log(T) should exist (T is close to identity) - let t = T(0); - let result = operator_log(&t); - assert!(result.is_some()); - - // log(S) should exist - let s = SZ(0); - let result = operator_log(&s); - assert!(result.is_some()); - } - - // --- to_matrix_with_size tests --- - - #[test] - fn test_to_matrix_with_size_embedding() { - // X(0) in 3-qubit space should be 8x8 - let x = X(0); - let mat = to_matrix_with_size(&x, 3); - assert_eq!(mat.nrows(), 8); - - // Should act as X on qubit 0, identity on others - // Check that |000> -> |001>, |001> -> |000> - assert!((mat[(1, 0)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(0, 1)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - } - - #[test] - fn test_to_matrix_preserves_unitarity() { - // Verify U * U† = I for various operators - let operators = vec![X(0), Y(0), Z(0), H(0), T(0), CX(0, 1)]; - - for op in operators { - let mat = to_matrix(&op); - let product = &mat * mat.adjoint(); - let identity: DMatrix = DMatrix::identity(mat.nrows(), mat.ncols()); - - for i in 0..mat.nrows() { - for j in 0..mat.ncols() { - assert!( - (product[(i, j)] - identity[(i, j)]).norm() < 1e-10, - "Unitarity failed for operator at ({i}, {j})" - ); - } - } - } - } - - // --- Conjugation matrix verification tests --- - - #[test] - fn test_conj_matrix_verification() { - // Verify A.conj(U) = U * A * U† via matrices - let a = X(0); - let u = H(0); - - let conj_result = a.conj(&u); - let conj_mat = to_matrix(&conj_result); - - // Compute U * A * U† directly - let u_mat = to_matrix(&u); - let a_mat = to_matrix(&a); - let expected = &u_mat * &a_mat * u_mat.adjoint(); - - assert!(matrices_equiv_up_to_phase(&conj_mat, &expected, 1e-10)); - } - - #[test] - fn test_conjdg_matrix_verification() { - // Verify A.conjdg(U) = U† * A * U via matrices - let a = X(0); - let u = H(0); - - let conjdg_result = a.conjdg(&u); - let conjdg_mat = to_matrix(&conjdg_result); - - // Compute U† * A * U directly - let u_mat = to_matrix(&u); - let a_mat = to_matrix(&a); - let expected = u_mat.adjoint() * &a_mat * &u_mat; - - assert!(matrices_equiv_up_to_phase(&conjdg_mat, &expected, 1e-10)); - } - - #[test] - fn test_conj_sz_gives_y() { - // X.conj(SZ) = SZ * X * SZ† should equal Y (up to phase) - let x = X(0); - let sz = SZ(0); - - let conj_result = x.conj(&sz); - let conj_mat = to_matrix(&conj_result); - - let y_mat = to_matrix(&Y(0)); - - assert!(matrices_equiv_up_to_phase(&conj_mat, &y_mat, 1e-10)); - } - - #[test] - fn test_conj_conjdg_inverse_via_matrix() { - // A.conj(U).conjdg(U) should equal A - let a = X(0); - let u = T(0); - - let forward = a.clone().conj(&u); - let back = forward.conjdg(&u); - let back_mat = to_matrix(&back); - - let a_mat = to_matrix(&a); - - assert!(matrices_equiv_up_to_phase(&back_mat, &a_mat, 1e-10)); - } - - // --- Multi-qubit conjugation tests --- - - #[test] - fn test_conj_multi_qubit_stabilizer() { - // Two-qubit stabilizer X⊗Z conjugated by CNOT - let stabilizer = X(0) & Z(1); - let cnot = CX(0, 1); - - let updated = stabilizer.conj(&cnot); - let updated_mat = to_matrix(&updated); - - // Compute CNOT * (X⊗Z) * CNOT† directly - let cnot_mat = to_matrix(&cnot); - let stab_mat = to_matrix(&stabilizer); - let expected = &cnot_mat * &stab_mat * cnot_mat.adjoint(); - - assert!(matrices_equiv_up_to_phase(&updated_mat, &expected, 1e-10)); - } - - #[test] - fn test_conj_by_two_qubit_gate() { - // Single-qubit Pauli conjugated by two-qubit gate - let x = X(0); - let cnot = CX(0, 1); - - let result = x.conj(&cnot); - let result_mat = to_matrix(&result); - - // CNOT * X(0) * CNOT† = X(0) ⊗ X(1) (CNOT propagates X from control to target) - let xx = X(0) & X(1); - let expected = to_matrix(&xx); - - assert!(matrices_equiv_up_to_phase(&result_mat, &expected, 1e-10)); - } - - // --- More two-qubit gate tests --- - - #[test] - fn test_cz_gate() { - // CZ = |0><0| ⊗ I + |1><1| ⊗ Z - use pecos_core::operator::CZ; - let cz = CZ(0, 1); - let mat = to_matrix(&cz); - - // CZ matrix: diag(1, 1, 1, -1) - assert!((mat[(0, 0)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(1, 1)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(2, 2)] - Complex64::new(1.0, 0.0)).norm() < 1e-10); - assert!((mat[(3, 3)] - Complex64::new(-1.0, 0.0)).norm() < 1e-10); - - // Off-diagonal should be zero - assert!(mat[(0, 1)].norm() < 1e-10); - assert!(mat[(1, 2)].norm() < 1e-10); - } - - #[test] - fn test_cz_symmetric() { - // CZ(0,1) should equal CZ(1,0) - use pecos_core::operator::CZ; - let cz_01 = CZ(0, 1); - let cz_10 = CZ(1, 0); - - let mat_01 = to_matrix(&cz_01); - let mat_10 = to_matrix(&cz_10); - - assert!(matrices_equiv_up_to_phase(&mat_01, &mat_10, 1e-10)); - } - - // --- Algebraic identity tests --- - - #[test] - fn test_adjoint_of_product() { - // (AB)† = B†A† - let a = H(0); - let b = T(0); - - let ab = a.clone() * b.clone(); - let ab_dagger = ab.dg(); - let ab_dagger_mat = to_matrix(&ab_dagger); - - let b_dagger_a_dagger = b.dg() * a.dg(); - let expected = to_matrix(&b_dagger_a_dagger); - - assert!(matrices_equiv_up_to_phase(&ab_dagger_mat, &expected, 1e-10)); - } - - #[test] - fn test_double_adjoint_identity() { - // (A†)† = A - let ops = vec![X(0), Y(0), H(0), T(0), CX(0, 1)]; - - for op in ops { - let double_dagger = op.dg().dg(); - let original_mat = to_matrix(&op); - let double_mat = to_matrix(&double_dagger); - - assert!(matrices_equiv_up_to_phase( - &original_mat, - &double_mat, - 1e-10 - )); - } - } - - #[test] - fn test_tensor_adjoint() { - // (A ⊗ B)† = A† ⊗ B† - let a = H(0); - let b = T(1); - - let tensor = a.clone() & b.clone(); - let tensor_dagger = tensor.dg(); - let tensor_dagger_mat = to_matrix(&tensor_dagger); - - let a_dagger_tensor_b_dagger = a.dg() & b.dg(); - let expected = to_matrix(&a_dagger_tensor_b_dagger); - - assert!(matrices_equiv_up_to_phase( - &tensor_dagger_mat, - &expected, - 1e-10 - )); - } - - // --- ToMatrix trait tests --- - - #[test] - fn test_to_matrix_trait_method() { - // Test that trait method gives same result as standalone function - let h = H(0); - - let via_function = to_matrix(&h); - let via_trait = h.to_matrix(); - - assert_eq!(via_function.nrows(), via_trait.nrows()); - assert_eq!(via_function.ncols(), via_trait.ncols()); - for i in 0..via_function.nrows() { - for j in 0..via_function.ncols() { - assert!((via_function[(i, j)] - via_trait[(i, j)]).norm() < 1e-10); - } - } - } - - #[test] - fn test_to_matrix_with_identity_tensor() { - // Test using Is() to get larger matrix - let x_extended = X(0) & Is(1..3); // X on qubit 0 in 3-qubit space - - let mat = x_extended.to_matrix(); - assert_eq!(mat.nrows(), 8); // 2^3 = 8 - - // Should match the standalone function - let expected = to_matrix_with_size(&X(0), 3); - assert!(matrices_equiv_up_to_phase(&mat, &expected, 1e-10)); - } - - #[test] - fn test_to_matrix_trait_chaining() { - // Verify trait works well with operator chaining - let circuit = H(0) * CX(0, 1) * H(0); - let mat = circuit.to_matrix(); - - assert_eq!(mat.nrows(), 4); // 2 qubits - - // Verify unitarity - let product = &mat * mat.adjoint(); - let identity: DMatrix = DMatrix::identity(4, 4); - assert!(matrices_equiv_up_to_phase(&product, &identity, 1e-10)); - } - - // --- Identity operator ToMatrix tests --- - - #[test] - fn test_identity_to_matrix_single_qubit() { - // I(0).to_matrix() should be 2x2 identity - let mat = I(0).to_matrix(); - let expected: DMatrix = DMatrix::identity(2, 2); - - assert_eq!(mat.nrows(), 2); - assert!(matrices_equiv_up_to_phase(&mat, &expected, 1e-10)); - } - - #[test] - fn test_identity_to_matrix_two_qubits() { - // Is(0..=1).to_matrix() should be 4x4 identity - let mat = Is(0..=1).to_matrix(); - let expected: DMatrix = DMatrix::identity(4, 4); - - assert_eq!(mat.nrows(), 4); - assert!(matrices_equiv_up_to_phase(&mat, &expected, 1e-10)); - } - - #[test] - fn test_identity_tensor_with_gate() { - // X(0) & I(1) should give X tensor I = 4x4 matrix - let op = X(0) & I(1); - let mat = op.to_matrix(); - - assert_eq!(mat.nrows(), 4); - - // Should equal X(0) extended to 2 qubits - let expected = to_matrix_with_size(&X(0), 2); - - assert!(matrices_equiv_up_to_phase(&mat, &expected, 1e-10)); - } - - #[test] - fn test_simplify_preserves_tensor_dimension() { - // (X(0) & I(1)).simplify() should preserve the 2-qubit space - let op = X(0) & I(1); - let simplified = op.simplify(); - - // Both should produce equivalent 4x4 matrices - let orig_mat = op.to_matrix(); - let simp_mat = simplified.to_matrix(); - - assert_eq!(orig_mat.nrows(), 4); - assert_eq!(simp_mat.nrows(), 4); - assert!(matrices_equiv_up_to_phase(&orig_mat, &simp_mat, 1e-10)); - } - - // --- PauliString ToMatrix tests --- - - #[test] - fn test_pauli_string_to_matrix_single() { - use pecos_core::PauliString; - - // Single X Pauli - let ps = PauliString::x(0); - let mat = ps.to_matrix(); - - // Should match X(0).to_matrix() - let x_mat = X(0).to_matrix(); - assert!(matrices_equiv_up_to_phase(&mat, &x_mat, 1e-10)); - } - - #[test] - fn test_pauli_string_to_matrix_multi() { - use pecos_core::{Pauli, PauliString}; - - // X on qubit 0, Z on qubit 1 - let ps = PauliString::from_paulis(&[Pauli::X, Pauli::Z]); - let mat = ps.to_matrix(); - - // Should match (X(0) & Z(1)).to_matrix() - let xz = X(0) & Z(1); - let expected = xz.to_matrix(); - assert!(matrices_equiv_up_to_phase(&mat, &expected, 1e-10)); - } - - #[test] - fn test_pauli_string_to_matrix_with_phase() { - use pecos_core::{Pauli, PauliString, QuarterPhase}; - - // -i * X - let ps = PauliString::from_paulis_with_phase(QuarterPhase::MinusI, &[Pauli::X]); - let mat = ps.to_matrix(); - - // Should be -i times X matrix - let x_mat = X(0).to_matrix(); - let neg_i = Complex64::new(0.0, -1.0); - let expected = x_mat * neg_i; - - assert!(matrices_equiv_up_to_phase(&mat, &expected, 1e-10)); - } - - #[test] - fn test_pauli_string_to_matrix_identity() { - use pecos_core::PauliString; - - // Identity PauliString - returns 1x1 identity (no qubits) - let ps = PauliString::identity(); - let mat = ps.to_matrix(); - - // Identity with no qubits defaults to 1 qubit -> 2x2 - let identity: DMatrix = DMatrix::identity(2, 2); - assert!(matrices_equiv_up_to_phase(&mat, &identity, 1e-10)); - } - - #[test] - fn test_pauli_string_matches_operator_pauli() { - use pecos_core::{Pauli, PauliString}; - - // Verify PauliString.to_matrix() matches Operator::Pauli.to_matrix() - let ps = PauliString::from_paulis(&[Pauli::Y, Pauli::Z]); - - // Convert to Operator::Pauli - let op = pecos_core::operator::Operator::Pauli(ps.clone()); - - let ps_mat = ps.to_matrix(); - let op_mat = op.to_matrix(); - - assert!(matrices_equiv_up_to_phase(&ps_mat, &op_mat, 1e-10)); - } -} diff --git a/crates/pecos-quantum/src/pauli_group.rs b/crates/pecos-quantum/src/pauli_group.rs index bd96fb70f..ee28a329f 100644 --- a/crates/pecos-quantum/src/pauli_group.rs +++ b/crates/pecos-quantum/src/pauli_group.rs @@ -39,7 +39,7 @@ //! //! ``` //! use pecos_quantum::PauliGroup; -//! use pecos_core::pauli::constructors::*; +//! use pecos_core::pauli::*; //! use pecos_core::pauli::algebra::i; //! //! // Generators with imaginary phases are allowed @@ -105,7 +105,7 @@ fn generator_order(phase: QuarterPhase) -> u32 { /// /// ``` /// use pecos_quantum::PauliGroup; -/// use pecos_core::pauli::constructors::*; +/// use pecos_core::pauli::*; /// use pecos_core::pauli::algebra::i; /// /// // A group with an imaginary-phase generator @@ -682,7 +682,7 @@ impl fmt::Display for PauliGroup { mod tests { use super::*; use pecos_core::pauli::algebra::i; - use pecos_core::pauli::constructors::*; + use pecos_core::pauli::*; // --- Construction and basic properties --- diff --git a/crates/pecos-quantum/src/pauli_sequence.rs b/crates/pecos-quantum/src/pauli_sequence.rs index 0c20c31be..a94aee614 100644 --- a/crates/pecos-quantum/src/pauli_sequence.rs +++ b/crates/pecos-quantum/src/pauli_sequence.rs @@ -30,7 +30,7 @@ //! //! ``` //! use pecos_quantum::PauliSequence; -//! use pecos_core::pauli::constructors::*; +//! use pecos_core::pauli::*; //! //! let paulis = PauliSequence::new(vec![ //! Zs(&[0, 1]), @@ -374,7 +374,7 @@ impl fmt::Display for F2Matrix { /// /// ``` /// use pecos_quantum::PauliSequence; -/// use pecos_core::pauli::constructors::*; +/// use pecos_core::pauli::*; /// use pecos_core::PauliOperator; /// /// let gens = PauliSequence::new(vec![ @@ -519,7 +519,7 @@ impl PauliSequence { /// /// ``` /// use pecos_quantum::PauliSequence; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// /// // Two independent generators /// let gens = PauliSequence::new(vec![Zs(&[0, 1]), Zs(&[1, 2])]); @@ -545,7 +545,7 @@ impl PauliSequence { /// /// ``` /// use pecos_quantum::PauliSequence; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// /// let gens = PauliSequence::new(vec![Zs(&[0, 1]), Zs(&[1, 2])]); /// @@ -663,7 +663,7 @@ impl PauliSequence { /// /// ``` /// use pecos_quantum::PauliSequence; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// /// // Commuting generators /// let gens = PauliSequence::new(vec![Zs(&[0, 1]), Zs(&[1, 2])]); @@ -760,7 +760,7 @@ impl PauliSequence { /// /// ``` /// use pecos_quantum::PauliSequence; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// /// // Repetition code: ZZI, IZZ on 3 qubits /// // Centralizer dimension = 2n - rank = 6 - 2 = 4 @@ -840,7 +840,7 @@ impl PauliSequence { /// /// ``` /// use pecos_quantum::PauliSequence; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// /// let seq = PauliSequence::new(vec![X(0) & Z(2), Z(1)]); /// assert_eq!(seq.to_sparse_str(), "+X0 Z2\n+Z1"); @@ -911,7 +911,7 @@ impl fmt::Display for PauliSequence { #[cfg(test)] mod tests { use super::*; - use pecos_core::pauli::constructors::*; + use pecos_core::pauli::*; #[test] fn test_new() { diff --git a/crates/pecos-quantum/src/pauli_set.rs b/crates/pecos-quantum/src/pauli_set.rs index 41cdf83e2..8e947b5d6 100644 --- a/crates/pecos-quantum/src/pauli_set.rs +++ b/crates/pecos-quantum/src/pauli_set.rs @@ -34,7 +34,7 @@ //! //! ``` //! use pecos_quantum::PauliSet; -//! use pecos_core::pauli::constructors::*; +//! use pecos_core::pauli::*; //! //! let mut set = PauliSet::new(); //! set.insert(&X(0)); @@ -112,7 +112,7 @@ impl PauliKey { /// /// ``` /// use pecos_quantum::PauliSet; -/// use pecos_core::pauli::constructors::*; +/// use pecos_core::pauli::*; /// /// let a = PauliSet::from_iter([X(0), Z(1), X(0) & Z(1)]); /// let b = PauliSet::from_iter([Z(1), Y(2)]); @@ -233,7 +233,7 @@ impl PauliSet { /// /// ``` /// use pecos_quantum::PauliSet; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// /// let commuting = PauliSet::from_iter([Zs(&[0, 1]), Zs(&[1, 2])]); /// assert!(commuting.is_abelian()); @@ -262,7 +262,7 @@ impl PauliSet { /// /// ``` /// use pecos_quantum::PauliSet; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// /// let set = PauliSet::from_iter([X(0), Z(1)]); /// let s = set.to_sparse_str(); @@ -283,7 +283,7 @@ impl PauliSet { /// /// ``` /// use pecos_quantum::PauliSet; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// /// let set = PauliSet::from_iter([X(0), Z(1)]); /// let s = set.to_dense_str(); @@ -308,7 +308,7 @@ impl FromStr for PauliSet { /// /// ``` /// use pecos_quantum::PauliSet; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// use std::str::FromStr; /// /// let set: PauliSet = "{X0, Z1}".parse().unwrap(); @@ -415,7 +415,7 @@ impl fmt::Display for PauliSet { #[cfg(test)] mod tests { use super::*; - use pecos_core::pauli::constructors::*; + use pecos_core::pauli::*; #[test] fn test_new_empty() { diff --git a/crates/pecos-quantum/src/stabilizer_group.rs b/crates/pecos-quantum/src/stabilizer_group.rs index 856f52523..dea18b3a1 100644 --- a/crates/pecos-quantum/src/stabilizer_group.rs +++ b/crates/pecos-quantum/src/stabilizer_group.rs @@ -31,7 +31,7 @@ //! //! ``` //! use pecos_quantum::PauliStabilizerGroup; -//! use pecos_core::pauli::constructors::*; +//! use pecos_core::pauli::*; //! //! // Repetition code stabilizers //! let stab = PauliStabilizerGroup::new(vec![ @@ -94,7 +94,7 @@ impl std::error::Error for PauliStabilizerGroupError {} /// /// ``` /// use pecos_quantum::PauliStabilizerGroup; -/// use pecos_core::pauli::constructors::*; +/// use pecos_core::pauli::*; /// /// // 5-qubit code stabilizers: XZZXI, IXZZX, XIXZZ, ZXIXZ /// let stab = PauliStabilizerGroup::new(vec![ @@ -245,7 +245,7 @@ impl PauliStabilizerGroup { /// /// ``` /// use pecos_quantum::PauliStabilizerGroup; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// use pecos_core::PauliOperator; /// /// let stab = PauliStabilizerGroup::new(vec![Zs(&[0, 1]), Zs(&[1, 2])]).unwrap(); @@ -284,7 +284,7 @@ impl PauliStabilizerGroup { /// /// ``` /// use pecos_quantum::PauliStabilizerGroup; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// use pecos_core::PauliOperator; /// /// let stab = PauliStabilizerGroup::new(vec![Zs(&[0, 1]), Zs(&[1, 2])]).unwrap(); @@ -315,7 +315,7 @@ impl PauliStabilizerGroup { /// /// ``` /// use pecos_quantum::PauliStabilizerGroup; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// /// let stab = PauliStabilizerGroup::new(vec![Zs(&[0, 1]), Zs(&[1, 2])]).unwrap(); /// let elements: Vec<_> = stab.elements().collect(); @@ -375,7 +375,7 @@ impl PauliStabilizerGroup { /// /// ``` /// use pecos_quantum::PauliStabilizerGroup; - /// use pecos_core::pauli::constructors::*; + /// use pecos_core::pauli::*; /// use pecos_core::clifford_rep::CliffordRep; /// /// // Repetition code stabilizers: ZZ_, _ZZ @@ -497,7 +497,7 @@ impl fmt::Display for PauliStabilizerGroup { #[cfg(test)] mod tests { use super::*; - use pecos_core::pauli::constructors::*; + use pecos_core::pauli::*; use pecos_core::{Pauli, PauliOperator}; #[test] diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index fd7648778..03bcf578b 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -1184,21 +1184,25 @@ impl TickCircuit { idx } - /// Place a Pauli operator annotation. - pub fn pauli_operator(&mut self, mut pauli: pecos_core::PauliString) -> usize { + /// Place a tracked-operator annotation. + pub fn tracked_operator(&mut self, mut pauli: pecos_core::PauliString) -> usize { pauli.set_phase(pecos_core::QuarterPhase::PlusOne); let idx = self.annotations.len(); self.annotations.push(PauliAnnotation { pauli, - kind: AnnotationKind::Operator, + kind: AnnotationKind::TrackedOperator, label: None, }); idx } - /// Place a labeled Pauli operator annotation. - pub fn pauli_operator_labeled(&mut self, label: &str, pauli: pecos_core::PauliString) -> usize { - let idx = self.pauli_operator(pauli); + /// Place a labeled tracked-operator annotation. + pub fn tracked_operator_labeled( + &mut self, + label: &str, + pauli: pecos_core::PauliString, + ) -> usize { + let idx = self.tracked_operator(pauli); self.annotations[idx].label = Some(label.to_string()); idx } @@ -2286,7 +2290,7 @@ impl From<&TickCircuit> for DagCircuit { measurement_nodes: dag_nodes, } } - AnnotationKind::Operator => AnnotationKind::Operator, + AnnotationKind::TrackedOperator => AnnotationKind::TrackedOperator, }; dag.add_annotation(PauliAnnotation { pauli: ann.pauli.clone(), @@ -3299,7 +3303,7 @@ mod tests { #[test] fn test_tick_circuit_annotations() { - use pecos_core::pauli::constructors::X; + use pecos_core::pauli::X; let mut tc = TickCircuit::new(); tc.tick().pz(&[0, 1, 2]); @@ -3311,7 +3315,7 @@ mod tests { tc.detector_labeled("Z_check", &ms); tc.observable_labeled("logical_Z", &ms); - tc.pauli_operator_labeled("logical_X", X(0) & X(1)); + tc.tracked_operator_labeled("logical_X", X(0) & X(1)); assert_eq!(tc.annotations().len(), 3); assert_eq!(tc.annotations()[0].label.as_deref(), Some("Z_check")); @@ -3321,7 +3325,7 @@ mod tests { #[test] fn test_tick_to_dag_annotation_transfer() { - use pecos_core::pauli::constructors::Z; + use pecos_core::pauli::Z; let mut tc = TickCircuit::new(); tc.tick().pz(&[0, 1, 2]); @@ -3329,7 +3333,7 @@ mod tests { let ms = tc.tick().mz(&[2]); tc.detector_labeled("det0", &ms); tc.observable_labeled("obs0", &ms); - tc.pauli_operator_labeled("op0", Z(0) & Z(1)); + tc.tracked_operator_labeled("op0", Z(0) & Z(1)); let dag = DagCircuit::from(&tc); @@ -3350,13 +3354,13 @@ mod tests { )); assert!(matches!( dag.annotations()[2].kind, - crate::dag_circuit::AnnotationKind::Operator + crate::dag_circuit::AnnotationKind::TrackedOperator )); } #[test] fn test_dag_to_tick_annotation_transfer() { - use pecos_core::pauli::constructors::X; + use pecos_core::pauli::X; let mut dag = DagCircuit::new(); dag.pz(&[0, 1]); @@ -3364,7 +3368,7 @@ mod tests { let ms = dag.mz(&[0, 1]); dag.detector_labeled("d0", &[ms[0]]); dag.observable_labeled("o0", &[ms[0], ms[1]]); - dag.pauli_operator_labeled("p0", X(0) & X(1)); + dag.tracked_operator_labeled("p0", X(0) & X(1)); let tc = TickCircuit::from(&dag); @@ -3376,7 +3380,7 @@ mod tests { #[test] fn test_annotation_round_trip() { - use pecos_core::pauli::constructors::X; + use pecos_core::pauli::X; // Build TickCircuit with annotations let mut tc1 = TickCircuit::new(); @@ -3387,7 +3391,7 @@ mod tests { tc1.detector_labeled("syndr", &ms); let ms_data = tc1.tick().mz(&[0, 1]); tc1.observable_labeled("log_Z", &ms_data); - tc1.pauli_operator_labeled("log_X", X(0) & X(1)); + tc1.tracked_operator_labeled("log_X", X(0) & X(1)); // TickCircuit -> DagCircuit -> TickCircuit let dag = DagCircuit::from(&tc1); diff --git a/crates/pecos-quantum/src/unitary_matrix.rs b/crates/pecos-quantum/src/unitary_matrix.rs index 79b873d0a..38e36b4d4 100644 --- a/crates/pecos-quantum/src/unitary_matrix.rs +++ b/crates/pecos-quantum/src/unitary_matrix.rs @@ -23,7 +23,7 @@ //! //! ``` //! use pecos_quantum::unitary_matrix::ToMatrix; -//! use pecos_core::unitary_rep::X; +//! use pecos_core::unitary::X; //! //! let x = X(0); //! let matrix = x.to_matrix(); // Method style @@ -56,7 +56,7 @@ use pecos_core::{Angle64, Op, Pauli, PauliString, Phase}; /// /// ``` /// use pecos_quantum::unitary_matrix::{UnitaryMatrix, ToMatrix}; -/// use pecos_core::unitary_rep::{X, Z}; +/// use pecos_core::unitary::{X, Z}; /// /// let mx = X(0).to_matrix(); /// let mz = Z(0).to_matrix(); @@ -1048,7 +1048,7 @@ impl fmt::Display for UnitaryMatrix { /// /// ``` /// use pecos_quantum::unitary_matrix::ToMatrix; -/// use pecos_core::unitary_rep::{X, H, CX, Is}; +/// use pecos_core::unitary::{X, H, CX, Is}; /// /// // Single qubit gate /// let x_matrix = X(0).to_matrix(); @@ -1123,13 +1123,17 @@ impl ToMatrix for Unitary { } impl ToMatrix for Op { - /// Converts to a matrix. Returns the zero matrix for channels (non-unitary ops). + /// Converts to a matrix. + /// + /// # Panics + /// + /// Panics for Gate-level or Channel-level operations, which do not have a + /// unitary matrix representation. fn to_matrix(&self) -> UnitaryMatrix { match self.clone().into_unitary() { Some(ur) => to_matrix(&ur), None => { - // Channel ops don't have a unitary matrix - panic!("Cannot convert non-unitary Op (Channel) to a matrix") + panic!("Cannot convert non-unitary Op (Gate/Channel) to a matrix") } } } @@ -1144,7 +1148,7 @@ impl ToMatrix for Op { /// /// ``` /// use pecos_quantum::unitary_matrix::to_matrix; -/// use pecos_core::unitary_rep::X; +/// use pecos_core::unitary::X; /// use num_complex::Complex64; /// /// let x = X(0); @@ -1252,7 +1256,7 @@ fn to_matrix_with_size_impl(op: &UnitaryRep, num_qubits: usize) -> DMatrix UnitaryMatrix { /// /// ``` /// use pecos_quantum::unitary_matrix::{unitary_log, to_matrix}; -/// use pecos_core::unitary_rep::X; +/// use pecos_core::unitary::X; /// /// let x = X(0); /// if let Some(log_x) = unitary_log(&x) { @@ -1300,7 +1304,7 @@ pub fn unitary_log(op: &UnitaryRep) -> Option> { /// /// ``` /// use pecos_quantum::unitary_matrix::unitaries_equiv; -/// use pecos_core::unitary_rep::{X, Y, Z}; +/// use pecos_core::unitary::{X, Y, Z}; /// /// let x = X(0); /// let x2 = X(0); diff --git a/docs/development/foreign-plugins.md b/docs/development/foreign-plugins.md index c0dcf2783..041629656 100644 --- a/docs/development/foreign-plugins.md +++ b/docs/development/foreign-plugins.md @@ -389,7 +389,7 @@ printf("Passed %u/%u tests\n", report.tests_passed, report.tests_run); ### From Rust -```rust +```rust,ignore let report = pecos_foreign::conformance::run_conformance_tests(&mut sim); assert!(report.all_passed()); ``` @@ -439,10 +439,11 @@ When using foreign simulators with pecos-neo, the `gate_support` module (behind `neo` feature flag) automatically configures the `CircuitRunner` decomposition based on what the foreign simulator supports: -```rust +```rust,ignore use pecos_foreign::gate_support::configure_runner_for_foreign; -let sim = ForeignSimulator::new(handle, vtable); +let sim = unsafe { ForeignSimulator::new(handle, vtable, num_qubits) } + .expect("foreign simulator vtable must match PECOS"); let mut runner = configure_runner_for_foreign(&sim); // If sim supports rotations: runner uses RX, RZ, RZZ natively // Otherwise: Clifford-only, everything decomposes into {SZ, H, CX} diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index e966f7e2c..fcc279315 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -492,7 +492,7 @@ Tracked operators are Pauli operators that the catalog monitors for anticommutation with fault events. Unlike observables, they have no measurement records -- they are detected by forward Pauli propagation. -Add tracked operators to a circuit via `pauli_operator`: +Add tracked operators to a circuit via `tracked_operator`: ```python @@ -502,7 +502,7 @@ tc2.set_meta("num_measurements", "0") tc2.set_meta("detectors", "[]") tc2.set_meta("observables", "[]") # Track Z on qubit 0 -- X and Y faults after H anticommute with Z -tc2.pauli_operator(PauliString.from_str("Z"), label="track_Z0") +tc2.tracked_operator(PauliString.from_str("Z"), label="track_Z0") cat2 = fault_catalog(tc2, p1=0.01, p2=0.0, p_meas=0.0, p_prep=0.0) for loc in cat2: diff --git a/docs/user-guide/fault-tolerance.md b/docs/user-guide/fault-tolerance.md index dabe5955f..6ae5737a5 100644 --- a/docs/user-guide/fault-tolerance.md +++ b/docs/user-guide/fault-tolerance.md @@ -33,7 +33,8 @@ A code is **fault-tolerant at weight t** if no weight-t error is an undetectable ```rust use pecos_qec::{StabilizerCodeSpec, StabilizerFlipChecker, ErrorClass}; -use pecos_core::{Xs, Zs, PauliString, QuarterPhase}; +use pecos_core::{PauliString, QuarterPhase}; +use pecos_core::pauli::{Xs, Zs}; // Define a 3-qubit bit-flip code let code = StabilizerCodeSpec::builder(3) @@ -51,8 +52,7 @@ let checker = StabilizerFlipChecker::new(&code); ```rust use pecos_qec::{StabilizerCodeSpec, StabilizerFlipChecker, ErrorClass}; -use pecos_core::{Xs, Zs}; -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; let code = StabilizerCodeSpec::builder(3) .check(Zs([0, 1])) @@ -80,8 +80,7 @@ For detailed information about which stabilizers and logicals are affected: ```rust use pecos_qec::{StabilizerCodeSpec, StabilizerFlipChecker}; -use pecos_core::{Xs, Zs}; -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; let code = StabilizerCodeSpec::builder(3) .check(Zs([0, 1])).check(Zs([1, 2])) @@ -102,7 +101,7 @@ Enumerate all weight-t Pauli errors and classify each: ```rust use pecos_qec::{StabilizerCodeSpec, StabilizerFlipChecker}; -use pecos_core::{Xs, Zs}; +use pecos_core::pauli::{Xs, Zs}; let code = StabilizerCodeSpec::builder(3) .check(Zs([0, 1])).check(Zs([1, 2])) @@ -129,7 +128,7 @@ For CSS codes, you can analyze X, Y, and Z errors separately: ```rust use pecos_qec::{StabilizerCodeSpec, StabilizerFlipChecker}; -use pecos_core::{Xs, Zs}; +use pecos_core::pauli::{Xs, Zs}; let code = StabilizerCodeSpec::builder(3) .check(Zs([0, 1])).check(Zs([1, 2])) @@ -296,7 +295,7 @@ The `distance` module provides configurable distance search: ```rust use pecos_qec::{StabilizerCodeSpec, calculate_distance, DistanceSearchConfig}; -use pecos_core::{Xs, Zs}; +use pecos_core::pauli::{Xs, Zs}; let code = StabilizerCodeSpec::builder(7) .check(Xs([0, 2, 4, 6])) @@ -328,7 +327,7 @@ let result = calculate_distance(&code, &DistanceSearchConfig::with_max_weight(5) ```rust use pecos_qec::{StabilizerCodeSpec, find_min_weight_logicals_with_info, DistanceSearchConfig}; -use pecos_core::{Xs, Zs}; +use pecos_core::pauli::{Xs, Zs}; let code = StabilizerCodeSpec::builder(7) .check(Xs([0, 2, 4, 6])) @@ -357,7 +356,7 @@ When you have stabilizer generators but don't know the logical operators, `disco ```rust use pecos_qec::discover_logical_operators; -use pecos_core::pauli::constructors::Zs; +use pecos_core::pauli::Zs; // Define stabilizers for the 3-qubit bit-flip code let stabilizers = vec![Zs([0, 1]), Zs([1, 2])]; diff --git a/docs/user-guide/gate-angle-types.md b/docs/user-guide/gate-angle-types.md index baaab2430..4f29dad83 100644 --- a/docs/user-guide/gate-angle-types.md +++ b/docs/user-guide/gate-angle-types.md @@ -119,7 +119,7 @@ The `phase!` and `phase_turn!` macros wrap angles into `PhaseValue` for use with ```rust use pecos_core::{phase, phase_turn}; -use pecos_core::unitary_rep::X; +use pecos_core::unitary::X; // Global phase applied to a gate let op = phase!(pi / 4) * X(0); // e^{i*pi/4} * X diff --git a/docs/user-guide/quantum-operator-algebra.md b/docs/user-guide/quantum-operator-algebra.md index 92e3c598d..05ebc6bb3 100644 --- a/docs/user-guide/quantum-operator-algebra.md +++ b/docs/user-guide/quantum-operator-algebra.md @@ -15,7 +15,7 @@ This guide covers PECOS's quantum operator type system: from single-qubit Paulis PECOS organizes quantum operators into a strict hierarchy where each level is a subset of the next: ```text -Pauli ⊂ Clifford ⊂ Unitary ⊂ Channel +Pauli ⊂ Clifford ⊂ Unitary ⊂ Gate ⊂ Channel ``` Each level has its own representation optimized for what it can express: @@ -25,9 +25,10 @@ Each level has its own representation optimized for what it can express: | Pauli | `PauliString` | Tensor products of I, X, Y, Z with phase | Exact commutation, symplectic algebra | | Clifford | `CliffordRep` | Gates that map Paulis to Paulis | Fast conjugation via Heisenberg picture | | Unitary | `UnitaryRep` | Any unitary (including non-Clifford) | Lazy expression tree with algebraic ops | -| Channel | `ChannelExpr` | Non-unitary operations (measurement, noise) | Compose and tensor arbitrary operations | +| Gate | `GateExpr` | Ideal circuit operations (unitary, preparation, measurement, reset) | Compose and tensor circuit operations | +| Channel | `ChannelExpr` | General CPTP maps and noise/decoherence operations | Compose and tensor arbitrary physical maps | -The unified `Op` type wraps all four and automatically promotes when you combine operators from different levels. +The unified `Op` type wraps all five and automatically promotes when you combine operators from different levels. --- @@ -38,7 +39,7 @@ The unified `Op` type wraps all four and automatically promotes when you combine The primary Pauli type. Stores a sparse list of non-identity single-qubit Paulis with a global phase from `{+1, -1, +i, -i}`. ```rust -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; use pecos_core::PauliOperator; // Single-qubit constructors @@ -64,7 +65,7 @@ let neg = -X(0); // -X ```rust use pecos_core::pauli::algebra::i; -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; let imag = i * X(0); // iX let neg_imag = -i * Y(1); // -iY @@ -73,7 +74,7 @@ let neg_imag = -i * Y(1); // -iY ### Key Operations ```rust -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; use pecos_core::PauliOperator; let a = X(0) & Z(1); @@ -126,7 +127,7 @@ Represents a Clifford gate via the Heisenberg picture: how it transforms each Pa ```rust use pecos_core::clifford_rep::CliffordRep; -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; // Hadamard on qubit 0: X -> Z, Z -> X let h = CliffordRep::h(0); @@ -155,7 +156,7 @@ The 24 single-qubit Clifford gates and 14 two-qubit entangling gates are also av A lazy expression tree that can represent any quantum unitary, including non-Clifford gates (T, arbitrary rotations). Supports composition, tensor products, and adjoint algebraically. ```rust -use pecos_core::unitary_rep::*; +use pecos_core::unitary::*; use pecos_core::Angle64; // Named gates @@ -183,19 +184,33 @@ let h_all = Hs([0, 1, 2]); // H on three qubits --- -## Level 4: Channels (Non-Unitary Operations) +## Level 4: Gates (Ideal Circuit Operations) -### ChannelExpr +### GateExpr -Represents non-unitary quantum operations: measurements, preparations, noise channels. +Represents ideal circuit operations: unitaries, measurements, preparations, resets, and their compositions. ```rust use pecos_core::op::*; -// Measurement and preparation +// Measurement, preparation, and reset let mz = MZ(0); // Z-basis measurement on qubit 0 let mx = MX(1); // X-basis measurement on qubit 1 let pz = PZ(0); // Prepare |0> on qubit 0 +let reset = Reset(0); // Reset to |0> +assert!(mz.is_gate()); +``` + +--- + +## Level 5: Channels (Physical Maps) + +### ChannelExpr + +Represents general CPTP maps, which PECOS usually uses for noise and decoherence. + +```rust +use pecos_core::op::*; // Noise channels let depol = Depolarizing(0.01, 0); // 1% depolarizing on qubit 0 @@ -203,18 +218,18 @@ let deph = Dephasing(0.02, 1); // 2% dephasing on qubit 1 let amp_damp = AmplitudeDamping(0.05, 0); // T1 decay let phase_damp = PhaseDamping(0.03, 0); // T2 dephasing let erasure = Erasure(0.01, 0); // Erasure channel -let reset = Reset(0); // Reset to |0> let leak = Leakage(0.001, 0); // Leakage to non-computational state // Custom Pauli channel let pauli_ch = PauliChannel(0.01, 0.01, 0.01, 0); // px, py, pz +assert!(depol.is_channel()); ``` --- ## The Unified `Op` Type -`Op` wraps all four levels and automatically promotes when you combine operators: +`Op` wraps all five levels and automatically promotes when you combine operators: ```rust use pecos_core::op::*; @@ -231,8 +246,12 @@ assert!(c.is_clifford()); let u = X(0) & H(3) & T(5); assert!(u.is_unitary()); -// Adding a measurement promotes to Channel -let ch = H(0) & MZ(1); +// Adding a measurement promotes to Gate +let g = H(0) & MZ(1); +assert!(g.is_gate()); + +// Adding noise promotes to Channel +let ch = g & Depolarizing(0.01, 2); assert!(ch.is_channel()); ``` @@ -299,7 +318,7 @@ An ordered list of Pauli strings with GF(2) symplectic analysis. No commutativit ```rust use pecos_quantum::PauliSequence; -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; let seq = PauliSequence::new(vec![ Zs([0, 1]), @@ -328,7 +347,7 @@ A set of distinct Pauli strings. Two strings are equal only if they have the sam ```rust use pecos_quantum::PauliSet; -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; let mut set = PauliSet::new(); set.insert(&X(0)); @@ -350,7 +369,7 @@ A commuting subgroup of the Pauli group. Generators may carry any `QuarterPhase` ```rust use pecos_quantum::PauliGroup; -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; use pecos_core::pauli::algebra::i; // Generators with imaginary phase @@ -373,7 +392,7 @@ The standard stabilizer group for QEC. All generators must commute and have phas ```rust use pecos_quantum::PauliStabilizerGroup; -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; // Repetition code stabilizers let stab = PauliStabilizerGroup::new(vec![ @@ -401,7 +420,7 @@ let transformed = stab.apply_clifford(&h); ```rust use pecos_quantum::{PauliSequence, PauliGroup, PauliStabilizerGroup, PauliSet}; -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; // Upward (widening) -- always succeeds let stab = PauliStabilizerGroup::new(vec![Zs([0, 1])]).unwrap(); @@ -429,7 +448,7 @@ The collection types feed into the QEC types in `pecos-qec`: ```rust use pecos_quantum::PauliStabilizerGroup; use pecos_qec::StabilizerCode; -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; // Build a stabilizer group let group = PauliStabilizerGroup::new(vec![ diff --git a/docs/user-guide/stabilizer-codes.md b/docs/user-guide/stabilizer-codes.md index 2348222c9..d1a048d6a 100644 --- a/docs/user-guide/stabilizer-codes.md +++ b/docs/user-guide/stabilizer-codes.md @@ -12,7 +12,7 @@ This guide covers working with Pauli strings and stabilizer codes in PECOS's Rus - Converting between code types ```hidden-rust -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; use pecos_core::PauliOperator; fn main() { @@ -27,7 +27,7 @@ Pauli strings are the fundamental building block. PECOS provides a concise const === ":fontawesome-brands-rust: Rust" ```rust - use pecos_core::pauli::constructors::*; + use pecos_core::pauli::*; // Single-qubit Paulis let x0 = X(0); // X on qubit 0 @@ -69,7 +69,7 @@ A `StabilizerCode` is defined by its stabilizer generators and a qubit count: ```rust use pecos_qec::StabilizerCode; - use pecos_core::pauli::constructors::*; + use pecos_core::pauli::*; // 3-qubit bit-flip repetition code: generators ZZI, IZZ let group = pecos_quantum::PauliStabilizerGroup::new(vec![ @@ -165,7 +165,7 @@ Check which stabilizers an error anticommutes with: ```rust use pecos_qec::StabilizerCode; -use pecos_core::pauli::constructors::*; +use pecos_core::pauli::*; let code = StabilizerCode::repetition(3); @@ -208,7 +208,7 @@ When stabilizer generators don't touch all qubits, the explicit `num_qubits` mat ```rust use pecos_qec::StabilizerCode; use pecos_quantum::PauliStabilizerGroup; -use pecos_core::pauli::constructors::Zs; +use pecos_core::pauli::Zs; // ZZ on qubits 0,1 -- but we declare 4 physical qubits let group = PauliStabilizerGroup::new(vec![ @@ -227,7 +227,7 @@ For fault tolerance analysis, use `StabilizerCodeSpec`. This stores explicit pai ```rust use pecos_qec::StabilizerCodeSpec; -use pecos_core::{Xs, Zs}; +use pecos_core::pauli::{Xs, Zs}; // Build a 3-qubit bit-flip code with explicit logicals let code = StabilizerCodeSpec::builder(3) @@ -269,7 +269,7 @@ spec.verify().unwrap(); ```rust use pecos_qec::{StabilizerCodeSpec, StabilizerFlipChecker}; -use pecos_core::{Xs, Zs}; +use pecos_core::pauli::{Xs, Zs}; let code = StabilizerCodeSpec::builder(7) .check(Xs([0, 2, 4, 6])) diff --git a/exp/pecos-eeg/src/builder.rs b/exp/pecos-eeg/src/builder.rs index 6a71314d9..c8d8efe76 100644 --- a/exp/pecos-eeg/src/builder.rs +++ b/exp/pecos-eeg/src/builder.rs @@ -205,7 +205,7 @@ fn build_detectors( pauli: bitmask, }); } - AnnotationKind::Operator => {} + AnnotationKind::TrackedOperator => {} } } diff --git a/python/pecos-rslib-exp/src/sim_neo_bindings.rs b/python/pecos-rslib-exp/src/sim_neo_bindings.rs index 8adbf3b11..15186eff8 100644 --- a/python/pecos-rslib-exp/src/sim_neo_bindings.rs +++ b/python/pecos-rslib-exp/src/sim_neo_bindings.rs @@ -925,7 +925,7 @@ fn build_rust_tick_circuit_from_gates( create_annotations_from_json(&mut tc, &s, &all_meas_refs, false); tc.set_meta("observables", Attribute::String(s)); } - copy_operator_annotations_from_python(py_tc, &mut tc)?; + copy_tracked_operator_annotations_from_python(py_tc, &mut tc)?; // Compact for performance tc.compact_ticks(); @@ -933,7 +933,7 @@ fn build_rust_tick_circuit_from_gates( Ok(tc) } -fn copy_operator_annotations_from_python( +fn copy_tracked_operator_annotations_from_python( py_tc: &pyo3::Bound<'_, pyo3::PyAny>, tc: &mut pecos_quantum::TickCircuit, ) -> PyResult<()> { @@ -944,21 +944,21 @@ fn copy_operator_annotations_from_python( for ann in annotations.try_iter()? { let ann = ann?; let kind: String = ann.get_item("kind")?.extract()?; - if kind != "operator" { + if kind != "tracked_operator" { continue; } let pauli_obj = ann.get_item("pauli")?; let pauli_text = pauli_obj.str()?.to_string(); let pauli = parse_python_pauli_string(&pauli_text).ok_or_else(|| { pyo3::exceptions::PyValueError::new_err(format!( - "Could not parse Pauli operator annotation: {pauli_text}" + "Could not parse tracked operator annotation: {pauli_text}" )) })?; let label: Option = ann.get_item("label")?.extract()?; if let Some(label) = label { - tc.pauli_operator_labeled(&label, pauli); + tc.tracked_operator_labeled(&label, pauli); } else { - tc.pauli_operator(pauli); + tc.tracked_operator(pauli); } } diff --git a/python/pecos-rslib/src/dag_circuit_bindings.rs b/python/pecos-rslib/src/dag_circuit_bindings.rs index 466260ad8..9b95b7547 100644 --- a/python/pecos-rslib/src/dag_circuit_bindings.rs +++ b/python/pecos-rslib/src/dag_circuit_bindings.rs @@ -1360,7 +1360,7 @@ impl PyDagCircuit { }) } - /// Place a Pauli operator annotation at this point in the circuit. + /// Place a tracked-operator annotation at this point in the circuit. /// /// Only faults BEFORE this annotation can flip the operator. /// Accepts a `PauliString`, which supports `PauliString.X(0) & PauliString.Z(1)`. @@ -1373,18 +1373,18 @@ impl PyDagCircuit { /// The annotation index. /// /// Example: - /// >>> from pecos import `PauliString` - /// >>> `dag.pauli_operator(PauliString.Z(0)` & PauliString.Z(1)) + /// >>> from pecos import PauliString + /// >>> dag.tracked_operator(PauliString.Z(0) & PauliString.Z(1)) #[pyo3(signature = (pauli, label=None))] - fn pauli_operator( + fn tracked_operator( &mut self, pauli: &crate::pauli_bindings::PauliString, label: Option, ) -> usize { if let Some(l) = label { - self.inner.pauli_operator_labeled(&l, pauli.inner.clone()) + self.inner.tracked_operator_labeled(&l, pauli.inner.clone()) } else { - self.inner.pauli_operator(pauli.inner.clone()) + self.inner.tracked_operator(pauli.inner.clone()) } } @@ -1403,7 +1403,7 @@ impl PyDagCircuit { let kind_str = match &ann.kind { pecos_quantum::AnnotationKind::Detector { .. } => "detector", pecos_quantum::AnnotationKind::Observable { .. } => "observable", - pecos_quantum::AnnotationKind::Operator => "operator", + pecos_quantum::AnnotationKind::TrackedOperator => "tracked_operator", }; dict.set_item("kind", kind_str)?; dict.set_item("label", &ann.label)?; @@ -2554,17 +2554,17 @@ impl PyTickCircuit { Ok(idx) } - /// Place a Pauli operator annotation. + /// Place a tracked-operator annotation. #[pyo3(signature = (pauli, label=None))] - fn pauli_operator( + fn tracked_operator( &mut self, pauli: &crate::pauli_bindings::PauliString, label: Option, ) -> usize { if let Some(l) = label { - self.inner.pauli_operator_labeled(&l, pauli.inner.clone()) + self.inner.tracked_operator_labeled(&l, pauli.inner.clone()) } else { - self.inner.pauli_operator(pauli.inner.clone()) + self.inner.tracked_operator(pauli.inner.clone()) } } @@ -2580,7 +2580,7 @@ impl PyTickCircuit { let kind_str = match &ann.kind { pecos_quantum::AnnotationKind::Detector { .. } => "detector", pecos_quantum::AnnotationKind::Observable { .. } => "observable", - pecos_quantum::AnnotationKind::Operator => "operator", + pecos_quantum::AnnotationKind::TrackedOperator => "tracked_operator", }; dict.set_item("kind", kind_str)?; dict.set_item("label", &ann.label)?; diff --git a/python/pecos-rslib/src/fault_tolerance_bindings.rs b/python/pecos-rslib/src/fault_tolerance_bindings.rs index 32821568d..aac4195a1 100644 --- a/python/pecos-rslib/src/fault_tolerance_bindings.rs +++ b/python/pecos-rslib/src/fault_tolerance_bindings.rs @@ -564,8 +564,8 @@ pub struct PyInfluenceBuilder { dag: DagCircuit, tracked_x_qubits: Vec, tracked_z_qubits: Vec, - pauli_operators: Vec, - use_circuit_pauli_operators: bool, + tracked_operators: Vec, + use_circuit_tracked_operators: bool, } #[pymethods] @@ -580,8 +580,8 @@ impl PyInfluenceBuilder { dag: dag.inner.clone(), tracked_x_qubits: Vec::new(), tracked_z_qubits: Vec::new(), - pauli_operators: Vec::new(), - use_circuit_pauli_operators: false, + tracked_operators: Vec::new(), + use_circuit_tracked_operators: false, } } @@ -622,7 +622,7 @@ impl PyInfluenceBuilder { /// /// Returns: /// Self for method chaining. - fn with_pauli_operator( + fn with_tracked_operator( mut slf: PyRefMut<'_, Self>, entries: Vec<(usize, String)>, ) -> PyResult> { @@ -640,7 +640,7 @@ impl PyInfluenceBuilder { Ok((pauli, pecos_core::QubitId::from(*qubit))) }) .collect::>()?; - slf.pauli_operators + slf.tracked_operators .push(pecos_core::PauliString::with_phase_and_paulis( pecos_core::QuarterPhase::PlusOne, paulis, @@ -650,14 +650,14 @@ impl PyInfluenceBuilder { /// Use annotations from the circuit (observables and Pauli operators). /// - /// Extracts observable and `pauli_operator()` annotations from the + /// Extracts observable and `tracked_operator()` annotations from the /// circuit. Pauli operators are tracked with positional awareness /// (only faults before each annotation's position affect it). /// /// Returns: /// Self for method chaining. fn with_circuit_annotations(mut slf: PyRefMut<'_, Self>) -> PyRefMut<'_, Self> { - slf.use_circuit_pauli_operators = true; + slf.use_circuit_tracked_operators = true; slf } @@ -680,11 +680,11 @@ impl PyInfluenceBuilder { builder = builder.with_z(&self.tracked_z_qubits); } - if self.use_circuit_pauli_operators { + if self.use_circuit_tracked_operators { builder = builder.with_circuit_annotations(&self.dag); } - for pauli in &self.pauli_operators { - builder = builder.with_pauli_operator(pauli.clone()); + for pauli in &self.tracked_operators { + builder = builder.with_tracked_operator(pauli.clone()); } let inner = builder.build(); @@ -693,11 +693,11 @@ impl PyInfluenceBuilder { fn __repr__(&self) -> String { format!( - "InfluenceBuilder(tracked_x={:?}, tracked_z={:?}, pauli_operators={}, circuit_annotations={})", + "InfluenceBuilder(tracked_x={:?}, tracked_z={:?}, tracked_operators={}, circuit_annotations={})", self.tracked_x_qubits, self.tracked_z_qubits, - self.pauli_operators.len(), - self.use_circuit_pauli_operators, + self.tracked_operators.len(), + self.use_circuit_tracked_operators, ) } } diff --git a/python/quantum-pecos/src/pecos/qec/surface/__init__.py b/python/quantum-pecos/src/pecos/qec/surface/__init__.py index 0afd6a189..ae1db8996 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/__init__.py +++ b/python/quantum-pecos/src/pecos/qec/surface/__init__.py @@ -19,12 +19,12 @@ # Circuit generation from geometry (unified abstraction) from pecos.qec.surface.circuit_builder import ( - CircuitOp, DagCircuitRenderer, GuppyRenderer, OpType, QubitAllocation, StimRenderer, + SurfaceCircuitStep, TickCircuitRenderer, build_surface_code_circuit, classify_stabilizer_boundary, @@ -152,7 +152,7 @@ "plot_patch", "plot_surface_code", # Circuit generation (unified abstraction) - "CircuitOp", + "SurfaceCircuitStep", "DagCircuitRenderer", "GuppyRenderer", "OpType", diff --git a/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py b/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py index 178baa68f..4cbd54ef0 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py +++ b/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py @@ -107,8 +107,8 @@ class OpType(Enum): @dataclass -class CircuitOp: - """A circuit operation.""" +class SurfaceCircuitStep: + """A surface-code circuit builder step.""" op_type: OpType qubits: list[int] = field(default_factory=list) @@ -167,7 +167,7 @@ def build_surface_code_circuit( num_rounds: int, basis: str = "Z", ancilla_budget: int | None = None, -) -> tuple[list[CircuitOp], QubitAllocation]: +) -> tuple[list[SurfaceCircuitStep], QubitAllocation]: """Build abstract circuit operations for a surface code memory experiment. This generates the circuit structure matching the Guppy implementation: @@ -235,44 +235,44 @@ def z_anc_q(stab_idx: int) -> int: # Get CNOT schedule cnot_rounds = compute_cnot_schedule(patch) - ops: list[CircuitOp] = [] + ops: list[SurfaceCircuitStep] = [] # ========================================================================= # prep_z_basis / prep_x_basis # ========================================================================= - ops.append(CircuitOp(OpType.COMMENT, label=f"prep_{basis.lower()}_basis")) + ops.append(SurfaceCircuitStep(OpType.COMMENT, label=f"prep_{basis.lower()}_basis")) # Allocate and reset data qubits - ops.extend(CircuitOp(OpType.ALLOC, [data_q(i)], f"data[{i}]") for i in range(num_data)) + ops.extend(SurfaceCircuitStep(OpType.ALLOC, [data_q(i)], f"data[{i}]") for i in range(num_data)) # For X-basis: H on each data qubit if basis.upper() == "X": - ops.extend(CircuitOp(OpType.H, [data_q(i)]) for i in range(num_data)) + ops.extend(SurfaceCircuitStep(OpType.H, [data_q(i)]) for i in range(num_data)) - ops.append(CircuitOp(OpType.TICK)) + ops.append(SurfaceCircuitStep(OpType.TICK)) # ========================================================================= # syndrome_extraction (called num_rounds times) # ========================================================================= for rnd in range(num_rounds): ops.append( - CircuitOp(OpType.COMMENT, label=f"syndrome_extraction round {rnd + 1}"), + SurfaceCircuitStep(OpType.COMMENT, label=f"syndrome_extraction round {rnd + 1}"), ) if effective_ancilla_budget == total_ancilla: - ops.extend(CircuitOp(OpType.ALLOC, [x_anc_q(s.index)], f"ax{s.index}") for s in geom.x_stabilizers) - ops.extend(CircuitOp(OpType.ALLOC, [z_anc_q(s.index)], f"az{s.index}") for s in geom.z_stabilizers) + ops.extend(SurfaceCircuitStep(OpType.ALLOC, [x_anc_q(s.index)], f"ax{s.index}") for s in geom.x_stabilizers) + ops.extend(SurfaceCircuitStep(OpType.ALLOC, [z_anc_q(s.index)], f"az{s.index}") for s in geom.z_stabilizers) - ops.append(CircuitOp(OpType.COMMENT, label="Hadamard on X ancillas")) - ops.extend(CircuitOp(OpType.H, [x_anc_q(s.index)], f"ax{s.index}") for s in geom.x_stabilizers) + ops.append(SurfaceCircuitStep(OpType.COMMENT, label="Hadamard on X ancillas")) + ops.extend(SurfaceCircuitStep(OpType.H, [x_anc_q(s.index)], f"ax{s.index}") for s in geom.x_stabilizers) - ops.append(CircuitOp(OpType.TICK)) + ops.append(SurfaceCircuitStep(OpType.TICK)) for rnd_idx, cx_round in enumerate(cnot_rounds): - ops.append(CircuitOp(OpType.COMMENT, label=f"CX round {rnd_idx + 1}")) + ops.append(SurfaceCircuitStep(OpType.COMMENT, label=f"CX round {rnd_idx + 1}")) for stab_type, stab_idx, data_idx in cx_round: if stab_type == "X": ops.append( - CircuitOp( + SurfaceCircuitStep( OpType.CX, [x_anc_q(stab_idx), data_q(data_idx)], f"X{stab_idx}", @@ -280,26 +280,30 @@ def z_anc_q(stab_idx: int) -> int: ) else: ops.append( - CircuitOp( + SurfaceCircuitStep( OpType.CX, [data_q(data_idx), z_anc_q(stab_idx)], f"Z{stab_idx}", ), ) - ops.append(CircuitOp(OpType.TICK)) + ops.append(SurfaceCircuitStep(OpType.TICK)) - ops.append(CircuitOp(OpType.COMMENT, label="Hadamard on X ancillas")) - ops.extend(CircuitOp(OpType.H, [x_anc_q(s.index)], f"ax{s.index}") for s in geom.x_stabilizers) + ops.append(SurfaceCircuitStep(OpType.COMMENT, label="Hadamard on X ancillas")) + ops.extend(SurfaceCircuitStep(OpType.H, [x_anc_q(s.index)], f"ax{s.index}") for s in geom.x_stabilizers) - ops.append(CircuitOp(OpType.COMMENT, label="Measure ancillas")) - ops.extend(CircuitOp(OpType.MEASURE, [x_anc_q(s.index)], f"sx{s.index}") for s in geom.x_stabilizers) - ops.extend(CircuitOp(OpType.MEASURE, [z_anc_q(s.index)], f"sz{s.index}") for s in geom.z_stabilizers) + ops.append(SurfaceCircuitStep(OpType.COMMENT, label="Measure ancillas")) + ops.extend( + SurfaceCircuitStep(OpType.MEASURE, [x_anc_q(s.index)], f"sx{s.index}") for s in geom.x_stabilizers + ) + ops.extend( + SurfaceCircuitStep(OpType.MEASURE, [z_anc_q(s.index)], f"sz{s.index}") for s in geom.z_stabilizers + ) - ops.append(CircuitOp(OpType.TICK)) + ops.append(SurfaceCircuitStep(OpType.TICK)) else: stabilizer_batches = _batched_stabilizers(patch, effective_ancilla_budget) for batch in stabilizer_batches: - ops.append(CircuitOp(OpType.COMMENT, label="Prepare ancillas")) + ops.append(SurfaceCircuitStep(OpType.COMMENT, label="Prepare ancillas")) batch_ancillas = { (stab_type, stab_idx): x_anc_q(stab_idx) if stab_type == "X" else z_anc_q(stab_idx) for stab_type, stab_idx in batch @@ -307,7 +311,7 @@ def z_anc_q(stab_idx: int) -> int: for stab_type, stab_idx in batch: ops.append( - CircuitOp( + SurfaceCircuitStep( OpType.ALLOC, [batch_ancillas[(stab_type, stab_idx)]], f"a{stab_type.lower()}{stab_idx}", @@ -316,23 +320,23 @@ def z_anc_q(stab_idx: int) -> int: x_stabilizers_in_batch = [stab_idx for stab_type, stab_idx in batch if stab_type == "X"] if x_stabilizers_in_batch: - ops.append(CircuitOp(OpType.COMMENT, label="Hadamard on X ancillas")) + ops.append(SurfaceCircuitStep(OpType.COMMENT, label="Hadamard on X ancillas")) ops.extend( - CircuitOp(OpType.H, [batch_ancillas[("X", stab_idx)]], f"ax{stab_idx}") + SurfaceCircuitStep(OpType.H, [batch_ancillas[("X", stab_idx)]], f"ax{stab_idx}") for stab_idx in x_stabilizers_in_batch ) - ops.append(CircuitOp(OpType.TICK)) + ops.append(SurfaceCircuitStep(OpType.TICK)) for rnd_idx, cx_round in enumerate(cnot_rounds): - ops.append(CircuitOp(OpType.COMMENT, label=f"CX round {rnd_idx + 1}")) + ops.append(SurfaceCircuitStep(OpType.COMMENT, label=f"CX round {rnd_idx + 1}")) for stab_type, stab_idx, data_idx in cx_round: ancilla_q = batch_ancillas.get((stab_type, stab_idx)) if ancilla_q is None: continue if stab_type == "X": ops.append( - CircuitOp( + SurfaceCircuitStep( OpType.CX, [ancilla_q, data_q(data_idx)], f"X{stab_idx}", @@ -340,45 +344,45 @@ def z_anc_q(stab_idx: int) -> int: ) else: ops.append( - CircuitOp( + SurfaceCircuitStep( OpType.CX, [data_q(data_idx), ancilla_q], f"Z{stab_idx}", ), ) - ops.append(CircuitOp(OpType.TICK)) + ops.append(SurfaceCircuitStep(OpType.TICK)) if x_stabilizers_in_batch: - ops.append(CircuitOp(OpType.COMMENT, label="Hadamard on X ancillas")) + ops.append(SurfaceCircuitStep(OpType.COMMENT, label="Hadamard on X ancillas")) ops.extend( - CircuitOp(OpType.H, [batch_ancillas[("X", stab_idx)]], f"ax{stab_idx}") + SurfaceCircuitStep(OpType.H, [batch_ancillas[("X", stab_idx)]], f"ax{stab_idx}") for stab_idx in x_stabilizers_in_batch ) - ops.append(CircuitOp(OpType.COMMENT, label="Measure ancillas")) + ops.append(SurfaceCircuitStep(OpType.COMMENT, label="Measure ancillas")) for stab_type, stab_idx in batch: measure_label = f"sx{stab_idx}" if stab_type == "X" else f"sz{stab_idx}" ops.append( - CircuitOp( + SurfaceCircuitStep( OpType.MEASURE, [batch_ancillas[(stab_type, stab_idx)]], measure_label, ), ) - ops.append(CircuitOp(OpType.TICK)) + ops.append(SurfaceCircuitStep(OpType.TICK)) # ========================================================================= # measure_z_basis / measure_x_basis # ========================================================================= - ops.append(CircuitOp(OpType.COMMENT, label=f"measure_{basis.lower()}_basis")) + ops.append(SurfaceCircuitStep(OpType.COMMENT, label=f"measure_{basis.lower()}_basis")) # For X-basis: H on each data qubit first if basis.upper() == "X": - ops.extend(CircuitOp(OpType.H, [data_q(i)]) for i in range(num_data)) + ops.extend(SurfaceCircuitStep(OpType.H, [data_q(i)]) for i in range(num_data)) # Measure all data qubits - ops.extend(CircuitOp(OpType.MEASURE, [data_q(i)], f"final[{i}]") for i in range(num_data)) + ops.extend(SurfaceCircuitStep(OpType.MEASURE, [data_q(i)], f"final[{i}]") for i in range(num_data)) return ops, allocation @@ -531,7 +535,7 @@ class CircuitRenderer(ABC): @abstractmethod def render( self, - ops: list[CircuitOp], + ops: list[SurfaceCircuitStep], allocation: QubitAllocation, patch: SurfacePatch, num_rounds: int, @@ -569,7 +573,7 @@ def __init__( def render( self, - ops: list[CircuitOp], + ops: list[SurfaceCircuitStep], allocation: QubitAllocation, patch: SurfacePatch, num_rounds: int, @@ -731,7 +735,7 @@ class GuppyRenderer(CircuitRenderer): def render( self, - _ops: list[CircuitOp], + _ops: list[SurfaceCircuitStep], _allocation: QubitAllocation, patch: SurfacePatch, _num_rounds: int, @@ -758,7 +762,7 @@ class DagCircuitRenderer(CircuitRenderer): def render( self, - ops: list[CircuitOp], + ops: list[SurfaceCircuitStep], _allocation: QubitAllocation, _patch: SurfacePatch, _num_rounds: int, @@ -831,7 +835,7 @@ def __init__(self, *, add_detectors: bool = True) -> None: def render( self, - ops: list[CircuitOp], + ops: list[SurfaceCircuitStep], allocation: QubitAllocation, patch: SurfacePatch, num_rounds: int, @@ -1988,7 +1992,6 @@ def simulate_error( # Process each gate as a potential error location for op_idx, (_tick_idx, gate_name, qubits, meas_idx) in enumerate(circuit_ops): - if gate_name in ("QAlloc", "PZ") and p_prep > 0: # Initialization error: X error after prep q = qubits[0] diff --git a/python/quantum-pecos/tests/conftest.py b/python/quantum-pecos/tests/conftest.py index ecfcd5563..7076b0d55 100644 --- a/python/quantum-pecos/tests/conftest.py +++ b/python/quantum-pecos/tests/conftest.py @@ -1,38 +1,7 @@ -# Copyright 2025 The PECOS Developers -# -# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with -# the License.You may obtain a copy of the License at -# -# https://www.apache.org/licenses/LICENSE-2.0 -# -# Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an -# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the -# specific language governing permissions and limitations under the License. +"""Shared pytest setup for the Python test suite.""" -"""Test configuration and shared fixtures.""" - -import pytest - -# Configure matplotlib to use non-interactive backend for tests (if available) -# This must be done before importing matplotlib.pyplot to avoid GUI backend issues on Windows -try: - import matplotlib as mpl - - mpl.use("Agg") -except ImportError: - # matplotlib is optional - only needed for visualization tests - pass - -# Note: llvmlite functionality is now always available via Rust (pecos_rslib.ir and pecos_rslib.binding) -# No need for conditional test skipping - - -def pytest_configure(config: pytest.Config) -> None: - """Register test-tree-local markers used by direct pytest invocations.""" - config.addinivalue_line( - "markers", - ( - "slow: mark tests that provide extra integration coverage but are " - "excluded from the default fast Python test lane" - ), - ) +# The test tree contains ``tests/pecos``. Pytest can import tests from that +# directory as a namespace package named ``pecos`` when an individual file is run +# in isolation. Import the installed/source package first so later +# ``import pecos`` statements resolve to the public PECOS package. +import pecos diff --git a/python/quantum-pecos/tests/docs/conftest.py b/python/quantum-pecos/tests/docs/conftest.py index 354dada23..7a5ed3ca1 100644 --- a/python/quantum-pecos/tests/docs/conftest.py +++ b/python/quantum-pecos/tests/docs/conftest.py @@ -63,7 +63,7 @@ def cuda_check() -> bool: @pytest.fixture(autouse=True) -def restore_cwd(): # noqa: ANN201 +def restore_cwd(): """Restore the current working directory after each test. Some tests (e.g., WASM examples) change the working directory, diff --git a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock index 0e1c33d84..913ec3734 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock +++ b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock @@ -2729,6 +2729,7 @@ dependencies = [ "pecos-decoder-core", "pecos-decoders", "pecos-engines", + "pecos-foreign", "pecos-hugr", "pecos-neo", "pecos-num", @@ -2761,6 +2762,21 @@ dependencies = [ "serde_json", ] +[[package]] +name = "pecos-foreign" +version = "0.2.0-dev.0" +dependencies = [ + "dirs", + "libloading 0.9.0", + "log", + "ndarray 0.17.2", + "pecos-core", + "pecos-decoder-core", + "pecos-engines", + "pecos-random", + "pecos-simulators", +] + [[package]] name = "pecos-hugr" version = "0.2.0-dev.0" diff --git a/python/quantum-pecos/tests/docs/rust_crate/Cargo.toml b/python/quantum-pecos/tests/docs/rust_crate/Cargo.toml index cd448a9ef..847ca2bb2 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/Cargo.toml +++ b/python/quantum-pecos/tests/docs/rust_crate/Cargo.toml @@ -17,6 +17,7 @@ pecos-num = { path = "../../../../../crates/pecos-num" } pecos-qec = { path = "../../../../../crates/pecos-qec" } pecos-decoders = { path = "../../../../../crates/pecos-decoders", features = ["ldpc"] } pecos-decoder-core = { path = "../../../../../crates/pecos-decoder-core" } +pecos-foreign = { path = "../../../../../crates/pecos-foreign" } pecos-random = { path = "../../../../../crates/pecos-random" } pecos-qasm = { path = "../../../../../crates/pecos-qasm" } pecos-programs = { path = "../../../../../crates/pecos-programs" } diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/development_foreign_plugins.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/development_foreign_plugins.rs index a49fafce5..aa983bbc2 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/development_foreign_plugins.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/development_foreign_plugins.rs @@ -12,16 +12,3 @@ fn test_development_foreign_plugins_rust_3() { plugin.name, plugin.decoder.is_some(), plugin.simulator.is_some()); } } - - - -#[test] -fn test_development_foreign_plugins_rust_4() -> Result<(), Box> { - use pecos_foreign::gate_support::configure_runner_for_foreign; - let sim = ForeignSimulator::new(handle, vtable); - let mut runner = configure_runner_for_foreign(&sim); - // If sim supports rotations: runner uses RX, RZ, RZZ natively - // Otherwise: Clifford-only, everything decomposes into {SZ, H, CX} - let outcomes = runner.apply_circuit(&mut sim, &commands)?; - Ok(()) -} diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_tolerance.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_tolerance.rs index 442214c2f..12c51b036 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_tolerance.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_tolerance.rs @@ -7,7 +7,8 @@ #[test] fn test_user_guide_fault_tolerance_rust_1() { - use pecos_core::{PauliString, QuarterPhase, Xs, Zs}; + use pecos_core::{PauliString, QuarterPhase}; + use pecos_core::pauli::{Xs, Zs}; use pecos_qec::{ErrorClass, StabilizerCodeSpec, StabilizerFlipChecker}; let code = StabilizerCodeSpec::builder(3) .check(Zs([0, 1])) @@ -24,8 +25,7 @@ fn test_user_guide_fault_tolerance_rust_1() { #[test] fn test_user_guide_fault_tolerance_rust_2() { - use pecos_core::pauli::constructors::*; - use pecos_core::{Xs, Zs}; + use pecos_core::pauli::*; use pecos_qec::{ErrorClass, StabilizerCodeSpec, StabilizerFlipChecker}; let code = StabilizerCodeSpec::builder(3) .check(Zs([0, 1])) @@ -51,8 +51,7 @@ fn test_user_guide_fault_tolerance_rust_2() { #[test] fn test_user_guide_fault_tolerance_rust_3() -> Result<(), Box> { - use pecos_core::pauli::constructors::*; - use pecos_core::{Xs, Zs}; + use pecos_core::pauli::*; use pecos_qec::{StabilizerCodeSpec, StabilizerFlipChecker}; let code = StabilizerCodeSpec::builder(3) .check(Zs([0, 1])).check(Zs([1, 2])) @@ -72,7 +71,7 @@ fn test_user_guide_fault_tolerance_rust_3() -> Result<(), Box Result<(), Box> { - use pecos_core::{Xs, Zs}; + use pecos_core::pauli::{Xs, Zs}; use pecos_qec::{StabilizerCodeSpec, StabilizerFlipChecker}; let code = StabilizerCodeSpec::builder(3) .check(Zs([0, 1])).check(Zs([1, 2])) @@ -98,7 +97,7 @@ fn test_user_guide_fault_tolerance_rust_4() -> Result<(), Box Result<(), Box> { - use pecos_core::{Xs, Zs}; + use pecos_core::pauli::{Xs, Zs}; use pecos_qec::{DemBuilder, DistanceSearchConfig, StabilizerCodeSpec, calculate_distance}; use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; use pecos_quantum::DagCircuit; @@ -259,7 +258,7 @@ let result = calculate_distance(&code, &DistanceSearchConfig::with_max_weight(5) #[test] fn test_user_guide_fault_tolerance_rust_10() -> Result<(), Box> { - use pecos_core::{Xs, Zs}; + use pecos_core::pauli::{Xs, Zs}; use pecos_qec::{DemBuilder, DistanceSearchConfig, StabilizerCodeSpec, find_min_weight_logicals_with_info}; use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; use pecos_quantum::DagCircuit; @@ -302,7 +301,7 @@ for op in &logicals { #[test] fn test_user_guide_fault_tolerance_rust_11() -> Result<(), Box> { - use pecos_core::pauli::constructors::Zs; + use pecos_core::pauli::Zs; use pecos_qec::{DemBuilder, discover_logical_operators}; use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; use pecos_quantum::DagCircuit; diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_gate_angle_types.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_gate_angle_types.rs index 0014195f7..2d173e251 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_gate_angle_types.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_gate_angle_types.rs @@ -92,7 +92,7 @@ fn test_user_guide_gate_angle_types_rust_5() { #[test] fn test_user_guide_gate_angle_types_rust_6() { use pecos_core::{phase, phase_turn}; - use pecos_core::unitary_rep::X; + use pecos_core::unitary::X; let op = phase!(pi / 4) * X(0); // e^{i*pi/4} * X let op = phase_turn!(1 / 8) * X(0); // same thing } diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_quantum_operator_algebra.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_quantum_operator_algebra.rs index 66fd6aa5b..5c54d3ba1 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_quantum_operator_algebra.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_quantum_operator_algebra.rs @@ -7,7 +7,7 @@ #[test] fn test_user_guide_quantum_operator_algebra_rust_1() { - use pecos_core::pauli::constructors::*; + use pecos_core::pauli::*; use pecos_core::PauliOperator; let p = X(0); // X on qubit 0 let q = Z(3); // Z on qubit 3 @@ -33,7 +33,7 @@ fn test_user_guide_quantum_operator_algebra_rust_1() { #[test] fn test_user_guide_quantum_operator_algebra_rust_2() { - use pecos_core::pauli::constructors::*; + use pecos_core::pauli::*; use pecos_core::pauli::algebra::i; let imag = i * X(0); // iX let neg_imag = -i * Y(1); // -iY @@ -43,7 +43,7 @@ fn test_user_guide_quantum_operator_algebra_rust_2() { #[test] fn test_user_guide_quantum_operator_algebra_rust_3() { - use pecos_core::pauli::constructors::*; + use pecos_core::pauli::*; use pecos_core::{PauliOperator, QuarterPhase}; let a = X(0) & Z(1); let b = Z(0) & X(1); @@ -80,7 +80,7 @@ fn test_user_guide_quantum_operator_algebra_rust_4() { #[test] fn test_user_guide_quantum_operator_algebra_rust_5() { - use pecos_core::pauli::constructors::*; + use pecos_core::pauli::*; use pecos_core::clifford_rep::CliffordRep; let h = CliffordRep::h(0); assert_eq!(*h.x_image(0), Z(0)); // H X H^dag = Z @@ -100,7 +100,7 @@ fn test_user_guide_quantum_operator_algebra_rust_5() { #[test] fn test_user_guide_quantum_operator_algebra_rust_6() { - use pecos_core::unitary_rep::*; + use pecos_core::unitary::*; use pecos_core::Angle64; let circuit = T(1) * CX(0, 1) * H(0); // apply H, then CX, then T @@ -123,7 +123,7 @@ fn test_user_guide_quantum_operator_algebra_rust_6() { } -// Measurement and preparation +// Measurement, preparation, and reset #[test] fn test_user_guide_quantum_operator_algebra_rust_7() { @@ -131,25 +131,33 @@ fn test_user_guide_quantum_operator_algebra_rust_7() { let mz = MZ(0); // Z-basis measurement on qubit 0 let mx = MX(1); // X-basis measurement on qubit 1 let pz = PZ(0); // Prepare |0> on qubit 0 + let reset = Reset(0); // Reset to |0> + assert!(mz.is_gate()); +} + + +// Noise channels - // Noise channels +#[test] +fn test_user_guide_quantum_operator_algebra_rust_8() { + use pecos_core::op::*; let depol = Depolarizing(0.01, 0); // 1% depolarizing on qubit 0 let deph = Dephasing(0.02, 1); // 2% dephasing on qubit 1 let amp_damp = AmplitudeDamping(0.05, 0); // T1 decay let phase_damp = PhaseDamping(0.03, 0); // T2 dephasing let erasure = Erasure(0.01, 0); // Erasure channel - let reset = Reset(0); // Reset to |0> let leak = Leakage(0.001, 0); // Leakage to non-computational state // Custom Pauli channel let pauli_ch = PauliChannel(0.01, 0.01, 0.01, 0); // px, py, pz + assert!(depol.is_channel()); } // Pauli & Pauli stays Pauli #[test] -fn test_user_guide_quantum_operator_algebra_rust_8() { +fn test_user_guide_quantum_operator_algebra_rust_9() { use pecos_core::op::*; let p = X(0) & Y(3); assert!(p.is_pauli()); @@ -162,15 +170,19 @@ fn test_user_guide_quantum_operator_algebra_rust_8() { let u = X(0) & H(3) & T(5); assert!(u.is_unitary()); - // Adding a measurement promotes to Channel - let ch = H(0) & MZ(1); + // Adding a measurement promotes to Gate + let g = H(0) & MZ(1); + assert!(g.is_gate()); + + // Adding noise promotes to Channel + let ch = g & Depolarizing(0.01, 2); assert!(ch.is_channel()); } #[test] -fn test_user_guide_quantum_operator_algebra_rust_9() { +fn test_user_guide_quantum_operator_algebra_rust_10() { use pecos_core::op::*; let p = X(0) & Z(1); let ps = p.as_pauli().unwrap(); // borrow the inner PauliString @@ -188,7 +200,7 @@ fn test_user_guide_quantum_operator_algebra_rust_9() { #[test] -fn test_user_guide_quantum_operator_algebra_rust_10() { +fn test_user_guide_quantum_operator_algebra_rust_11() { use pecos_core::op::*; let circuit = T(1) * CX(0, 1) * H(0); let inverse = circuit.dg(); // works for Pauli, Clifford, Unitary @@ -201,7 +213,7 @@ fn test_user_guide_quantum_operator_algebra_rust_10() { #[test] -fn test_user_guide_quantum_operator_algebra_rust_11() { +fn test_user_guide_quantum_operator_algebra_rust_12() { use pecos_core::op::*; let circuit = CX(0, 3) & H(5); assert_eq!(circuit.num_qubits(), 6); // spans qubits 0..5 @@ -211,8 +223,8 @@ fn test_user_guide_quantum_operator_algebra_rust_11() { #[test] -fn test_user_guide_quantum_operator_algebra_rust_12() { - use pecos_core::pauli::constructors::*; +fn test_user_guide_quantum_operator_algebra_rust_13() { + use pecos_core::pauli::*; use pecos_quantum::PauliSequence; let seq = PauliSequence::new(vec![ Zs([0, 1]), @@ -238,8 +250,8 @@ fn test_user_guide_quantum_operator_algebra_rust_12() { #[test] -fn test_user_guide_quantum_operator_algebra_rust_13() { - use pecos_core::pauli::constructors::*; +fn test_user_guide_quantum_operator_algebra_rust_14() { + use pecos_core::pauli::*; use pecos_quantum::PauliSet; let mut set = PauliSet::new(); set.insert(&X(0)); @@ -259,8 +271,8 @@ fn test_user_guide_quantum_operator_algebra_rust_13() { // Generators with imaginary phase #[test] -fn test_user_guide_quantum_operator_algebra_rust_14() { - use pecos_core::pauli::constructors::*; +fn test_user_guide_quantum_operator_algebra_rust_15() { + use pecos_core::pauli::*; use pecos_core::pauli::algebra::i; use pecos_quantum::PauliGroup; let group = PauliGroup::new(vec![ @@ -280,8 +292,8 @@ fn test_user_guide_quantum_operator_algebra_rust_14() { // Repetition code stabilizers #[test] -fn test_user_guide_quantum_operator_algebra_rust_15() -> Result<(), Box> { - use pecos_core::pauli::constructors::*; +fn test_user_guide_quantum_operator_algebra_rust_16() -> Result<(), Box> { + use pecos_core::pauli::*; use pecos_core::clifford_rep::CliffordRep; use pecos_quantum::PauliStabilizerGroup; let stab = PauliStabilizerGroup::new(vec![ @@ -309,8 +321,8 @@ fn test_user_guide_quantum_operator_algebra_rust_15() -> Result<(), Box None: dag = DagCircuit() dag.pz([0]) dag.h([0]) - dag.pauli_operator(PauliString.from_str("X"), label="x_check") + dag.tracked_operator(PauliString.from_str("X"), label="x_check") sampler = DemSampler.from_circuit(dag, p1=0.03, p2=0.0, p_meas=0.0, p_prep=0.0) @@ -180,7 +180,7 @@ def test_dem_events_split_observables_and_tracked_ops() -> None: dag = DagCircuit() dag.pz([0]) dag.h([0]) - dag.pauli_operator(PauliString.from_str("X"), label="x_check") + dag.tracked_operator(PauliString.from_str("X"), label="x_check") dag.mz([0]) dag.set_attr("num_measurements", "1") dag.set_attr("observables", '[{"id": 0, "records": [-1]}]') @@ -223,7 +223,7 @@ def test_sample_decode_count_ignores_tracked_ops() -> None: dag.pz([0]) dag.pz([1]) dag.h([1]) - dag.pauli_operator(PauliString.from_str("IZ"), label="tracked_z") + dag.tracked_operator(PauliString.from_str("IZ"), label="tracked_z") dag.mz([0]) dag.set_attr("num_measurements", "1") dag.set_attr("detectors", '[{"id": 0, "records": [-1]}]') @@ -264,7 +264,7 @@ def test_influence_map_tracks_dem_outputs_and_tracked_ops_separately() -> None: dag.h([0]) builder = InfluenceBuilder(dag) - builder.with_pauli_operator([(0, "X")]) + builder.with_tracked_operator([(0, "X")]) influence_map = builder.build() assert influence_map.num_tracked_ops > 0 diff --git a/python/quantum-pecos/tests/qec/test_fault_catalog.py b/python/quantum-pecos/tests/qec/test_fault_catalog.py index 2f71db43e..e33a00533 100644 --- a/python/quantum-pecos/tests/qec/test_fault_catalog.py +++ b/python/quantum-pecos/tests/qec/test_fault_catalog.py @@ -498,7 +498,7 @@ def test_yielded_locations_and_faults(self): def test_tracked_ops_are_distinct_from_observables(self): tc = TickCircuit() tc.tick().h([0]) - tc.pauli_operator(PauliString.from_str("Z"), label="tracked_z") + tc.tracked_operator(PauliString.from_str("Z"), label="tracked_z") tc.set_meta("detectors", "[]") tc.set_meta("observables", "[]") diff --git a/scripts/docs/generate_doc_tests.py b/scripts/docs/generate_doc_tests.py index c24b5fb40..457c4ac99 100755 --- a/scripts/docs/generate_doc_tests.py +++ b/scripts/docs/generate_doc_tests.py @@ -395,7 +395,7 @@ def extract_code_blocks(file_path: Path, language: str = "python") -> list[CodeB output_block_text = None output_mode = attrs["expect_output_mode"] if attrs["expect_output_block"]: - after_fence = content[match.end():] + after_fence = content[match.end() :] output_match = re.match(r"\s*```output\n(.*?)```", after_fence, re.DOTALL) if output_match: output_block_text = output_match.group(1).rstrip("\n") @@ -522,7 +522,7 @@ def _generate_guppy_body(block: CodeBlock) -> list[str]: " # Guppy needs file-based execution for inspect.getsourcelines()", " # Run in temp directory to avoid polluting project root with generated files", " with tempfile.TemporaryDirectory() as tmpdir:", - " temp_path = Path(tmpdir) / 'test_code.py'", + ' temp_path = Path(tmpdir) / "test_code.py"', " temp_path.write_text(code)", "", " result = subprocess.run(", @@ -548,10 +548,10 @@ def _generate_expect_error_body(block: CodeBlock) -> list[str]: # Guppy code needs subprocess execution # Run in temp directory to avoid polluting project root with generated files lines = [ + " import re", " import subprocess", " import sys", " import tempfile", - " import re", " from pathlib import Path", "", ' code = """', @@ -560,7 +560,7 @@ def _generate_expect_error_body(block: CodeBlock) -> list[str]: f' expected_pattern = r"{escaped_pattern}"', "", " with tempfile.TemporaryDirectory() as tmpdir:", - " temp_path = Path(tmpdir) / 'test_code.py'", + ' temp_path = Path(tmpdir) / "test_code.py"', " temp_path.write_text(code)", "", " result = subprocess.run(", @@ -571,16 +571,16 @@ def _generate_expect_error_body(block: CodeBlock) -> list[str]: " check=False,", " cwd=tmpdir,", " )", - " assert result.returncode != 0, 'Expected code to fail but it succeeded'", + ' assert result.returncode != 0, "Expected code to fail but it succeeded"', " assert re.search(expected_pattern, result.stderr), \\", ' f"Error did not match pattern {expected_pattern!r}:\\n{result.stderr}"', ] else: # Regular code can use subprocess with -c lines = [ + " import re", " import subprocess", " import sys", - " import re", "", ' code = """', *[line.rstrip() for line in escaped_code.split("\n")], @@ -594,7 +594,7 @@ def _generate_expect_error_body(block: CodeBlock) -> list[str]: " timeout=30,", " check=False,", " )", - " assert result.returncode != 0, 'Expected code to fail but it succeeded'", + ' assert result.returncode != 0, "Expected code to fail but it succeeded"', " assert re.search(expected_pattern, result.stderr), \\", ' f"Error did not match pattern {expected_pattern!r}:\\n{result.stderr}"', ] @@ -619,9 +619,9 @@ def _generate_rust_rustc_body(block: CodeBlock) -> list[str]: has_main = "fn main()" in block.code lines = [ + " import os", " import subprocess", " import tempfile", - " import os", " from pathlib import Path", "", ' code = """', @@ -688,9 +688,9 @@ def _generate_rust_expect_error_body(block: CodeBlock) -> list[str]: escaped_pattern = block.expect_error.replace('"', '\\"') if block.expect_error else "" return [ + " import re", " import subprocess", " import tempfile", - " import re", " from pathlib import Path", "", ' code = """', @@ -738,7 +738,7 @@ def _generate_expect_output_body(block: CodeBlock) -> list[str]: f' expected_output = "{escaped_output}"', "", " with tempfile.TemporaryDirectory() as tmpdir:", - " temp_path = Path(tmpdir) / 'test_code.py'", + ' temp_path = Path(tmpdir) / "test_code.py"', " temp_path.write_text(code)", "", " result = subprocess.run(", @@ -790,7 +790,7 @@ def _generate_expect_output_block_body(block: CodeBlock) -> list[str]: escaped_expected = block.expect_output_block.replace("\\", "\\\\").replace('"""', '\\"\\"\\"') use_ellipsis = block.expect_output_mode == "ellipsis" - lines = [ + return [ " import doctest", " import subprocess", " import sys", @@ -822,7 +822,6 @@ def _generate_expect_output_block_body(block: CodeBlock) -> list[str]: " )", ' pytest.fail(f"Output mismatch:\\n{diff}")', ] - return lines def generate_test_file(file_path: Path, blocks: list[CodeBlock]) -> str: @@ -845,7 +844,6 @@ def generate_test_file(file_path: Path, blocks: list[CodeBlock]) -> str: if needs_cuda_check: lines.extend( [ - "", "", "def _check_cuda() -> bool:", ' """Return True if CUDA toolkit and cupy are available."""', @@ -887,7 +885,6 @@ def generate_test_file(file_path: Path, blocks: list[CodeBlock]) -> str: if needs_cuda_rust_check: lines.extend( [ - "", "", "def _check_cuda_rust() -> bool:", ' """Return True if CUDA Rust bindings (pecos_rslib_cuda) are available."""', @@ -990,7 +987,7 @@ def cuda_check() -> bool: @pytest.fixture(autouse=True) -def restore_cwd(): # noqa: ANN201 +def restore_cwd(): """Restore the current working directory after each test. Some tests (e.g., WASM examples) change the working directory, From 3137e9de352d280cc5b8be740f5126b1124016ab Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 21:14:40 -0600 Subject: [PATCH 069/125] Refine operator and sampler infrastructure --- Cargo.lock | 1 + crates/benchmarks/benches/benchmarks.rs | 8 +- .../benches/modules/fault_catalog.rs | 434 +++ crates/pecos-core/src/channel.rs | 291 ++ crates/pecos-core/src/gate.rs | 472 +++ crates/pecos-core/src/lib.rs | 4 + crates/pecos-core/src/op.rs | 44 + .../fault_tolerance/dem_builder/builder.rs | 52 +- .../dem_builder/dem_sampler.rs | 45 +- .../dem_builder/mem_builder.rs | 85 +- .../src/fault_tolerance/dem_builder/types.rs | 10 +- .../src/fault_tolerance/fault_sampler.rs | 140 +- .../tests/per_gate_dem_builder_tests.rs | 14 +- .../tests/per_qubit_measurement_tests.rs | 5 +- .../pecos-qec/tests/per_qubit_noise_tests.rs | 27 +- .../pecos-qec/tests/stim_dem_export_tests.rs | 17 +- crates/pecos-quantum/Cargo.toml | 1 + crates/pecos-quantum/src/channel.rs | 2644 +++++++++++++++++ crates/pecos-quantum/src/dag_circuit.rs | 4 +- crates/pecos-quantum/src/lib.rs | 16 +- crates/pecos-quantum/src/measures.rs | 499 ++++ crates/pecos-quantum/src/unitary_matrix.rs | 118 + .../src/bitmask_pauli_prop.rs | 664 +++++ crates/pecos-simulators/src/gens.rs | 22 +- crates/pecos-simulators/src/lib.rs | 7 + crates/pecos-simulators/src/sparse_stab.rs | 22 + crates/pecos-simulators/src/stabilizer.rs | 16 + crates/pecos-simulators/src/state_access.rs | 1342 +++++++++ exp/pecos-lindblad/Cargo.toml | 2 +- exp/pecos-lindblad/src/basis.rs | 53 +- exp/pecos-lindblad/src/noise_models.rs | 6 +- exp/pecos-lindblad/src/pauli_lindblad.rs | 113 +- exp/pecos-lindblad/src/synthesis.rs | 2 +- exp/pecos-lindblad/tests/cross_path.rs | 2 +- exp/pecos-lindblad/tests/cx_theta_2q.rs | 2 +- exp/pecos-lindblad/tests/cz_theta_2q.rs | 2 +- exp/pecos-lindblad/tests/diff_helpers.rs | 2 +- exp/pecos-lindblad/tests/expm_smoke.rs | 2 +- exp/pecos-lindblad/tests/four_qubit_smoke.rs | 4 +- exp/pecos-lindblad/tests/inverse_fit.rs | 14 +- exp/pecos-lindblad/tests/inverse_fit_2q.rs | 14 +- exp/pecos-lindblad/tests/izz_crosstalk_3q.rs | 2 +- exp/pecos-lindblad/tests/noise_budget.rs | 2 +- exp/pecos-lindblad/tests/noise_models_api.rs | 4 +- exp/pecos-lindblad/tests/phase_noise_2q.rs | 14 +- exp/pecos-lindblad/tests/serde_roundtrip.rs | 6 +- exp/pecos-lindblad/tests/superop_synthesis.rs | 2 +- .../tests/synthesize_superop_full.rs | 2 +- .../tests/walsh_hadamard_roundtrip.rs | 2 +- 49 files changed, 6981 insertions(+), 275 deletions(-) create mode 100644 crates/benchmarks/benches/modules/fault_catalog.rs create mode 100644 crates/pecos-core/src/channel.rs create mode 100644 crates/pecos-core/src/gate.rs create mode 100644 crates/pecos-quantum/src/channel.rs create mode 100644 crates/pecos-quantum/src/measures.rs create mode 100644 crates/pecos-simulators/src/bitmask_pauli_prop.rs create mode 100644 crates/pecos-simulators/src/state_access.rs diff --git a/Cargo.lock b/Cargo.lock index 80f78d65c..24b8bce23 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -4320,6 +4320,7 @@ dependencies = [ "num-complex 0.4.6", "pecos-core", "pecos-num", + "pecos-random", "pecos-simulators", "smallvec", "tket", diff --git a/crates/benchmarks/benches/benchmarks.rs b/crates/benchmarks/benches/benchmarks.rs index d32dad430..c0d4afb9e 100644 --- a/crates/benchmarks/benches/benchmarks.rs +++ b/crates/benchmarks/benches/benchmarks.rs @@ -21,6 +21,7 @@ mod modules { pub mod dem_builder; pub mod dem_sampler; pub mod dod_statevec; + pub mod fault_catalog; pub mod quizx_eval; pub mod stab_vec; // TODO: pub mod hadamard_ops; @@ -57,9 +58,9 @@ use modules::sparse_stab_vs_cpp; use modules::stab_mps_vs_stab_vec; use modules::{ allocation_overhead, cpu_stabilizer_comparison, dem_builder, dem_sampler, dod_statevec, - measurement_sampling, native_statevec_comparison, noise_models, pecos_neo_comparison, - quizx_eval, rng, set_ops, sparse_stab_w_vs_y, sparse_state_vec, stab_vec, stabilizer_sims, - state_vec_sims, surface_code, trig, + fault_catalog, measurement_sampling, native_statevec_comparison, noise_models, + pecos_neo_comparison, quizx_eval, rng, set_ops, sparse_stab_w_vs_y, sparse_state_vec, stab_vec, + stabilizer_sims, state_vec_sims, surface_code, trig, }; fn all_benchmarks(c: &mut Criterion) { @@ -72,6 +73,7 @@ fn all_benchmarks(c: &mut Criterion) { dem_builder::benchmarks(c); dem_sampler::benchmarks(c); dod_statevec::benchmarks(c); + fault_catalog::benchmarks(c); #[cfg(feature = "gpu-sims")] gpu_influence_sampler::benchmarks(c); measurement_sampling::benchmarks(c); diff --git a/crates/benchmarks/benches/modules/fault_catalog.rs b/crates/benchmarks/benches/modules/fault_catalog.rs new file mode 100644 index 000000000..d8225e033 --- /dev/null +++ b/crates/benchmarks/benches/modules/fault_catalog.rs @@ -0,0 +1,434 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Parameterized fault-catalog benchmarks. +//! +//! These benchmarks cover the Rust-side sweep path before doing packed +//! performance work: +//! - structural catalog construction from a `TickCircuit`, +//! - applying a concrete noise point with `with_noise`, +//! - projecting the richer catalog into raw-measurement mechanisms, and +//! - amortized noise sweeps compared with direct concrete catalog builds. + +use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, measurement::Measurement}; +use pecos_qec::SurfaceCode; +use pecos_qec::fault_tolerance::fault_sampler::{ + FaultCatalog, StochasticNoiseParams, build_fault_catalog, build_fault_table, +}; +use pecos_quantum::{Attribute, TickCircuit, TickMeasRef}; +use std::hint::black_box; + +const DISTANCES: &[usize] = &[3, 5, 7, 9, 11]; +const SWEEP_NOISES: &[StochasticNoiseParams] = &[ + StochasticNoiseParams { + p1: 0.00005, + p2: 0.0005, + p_meas: 0.0005, + p_prep: 0.0005, + }, + StochasticNoiseParams { + p1: 0.0001, + p2: 0.001, + p_meas: 0.001, + p_prep: 0.001, + }, + StochasticNoiseParams { + p1: 0.0002, + p2: 0.002, + p_meas: 0.002, + p_prep: 0.002, + }, + StochasticNoiseParams { + p1: 0.0005, + p2: 0.005, + p_meas: 0.005, + p_prep: 0.005, + }, +]; + +#[derive(Debug)] +struct MemoryCircuit { + circuit: TickCircuit, + distance: usize, + rounds: usize, + num_measurements: usize, + num_detectors: usize, + num_observables: usize, +} + +#[derive(Debug)] +struct CatalogShape { + locations: usize, + alternatives: usize, +} + +pub fn benchmarks(c: &mut Criterion) { + bench_from_circuit(c); + bench_with_noise(c); + bench_to_mechanisms(c); + bench_noise_sweeps(c); +} + +fn bench_from_circuit(c: &mut Criterion) { + let mut group = c.benchmark_group("fault_catalog/from_circuit"); + + for memory in surface_memory_circuits() { + let shape = catalog_shape(&memory.circuit); + group.throughput(Throughput::Elements(as_u64(shape.locations))); + group.bench_with_input(bench_id(&memory, &shape), &memory, |b, memory| { + b.iter(|| { + black_box(FaultCatalog::from_circuit(black_box(&memory.circuit))) + .expect("surface memory circuit should be supported") + }); + }); + } + + group.finish(); +} + +fn bench_with_noise(c: &mut Criterion) { + let mut group = c.benchmark_group("fault_catalog/with_noise"); + let noise = representative_noise(); + + for memory in surface_memory_circuits() { + let shape = catalog_shape(&memory.circuit); + group.throughput(Throughput::Elements(as_u64(shape.locations))); + group.bench_with_input(bench_id(&memory, &shape), &memory, |b, memory| { + b.iter_batched( + || { + FaultCatalog::from_circuit(&memory.circuit) + .expect("surface memory circuit should be supported") + }, + |mut catalog| { + catalog.with_noise(black_box(&noise)); + black_box(catalog) + }, + BatchSize::SmallInput, + ); + }); + } + + group.finish(); +} + +fn bench_to_mechanisms(c: &mut Criterion) { + let mut group = c.benchmark_group("fault_catalog/to_mechanisms"); + let noise = representative_noise(); + + for memory in surface_memory_circuits() { + let shape = catalog_shape(&memory.circuit); + group.throughput(Throughput::Elements(as_u64(shape.alternatives))); + group.bench_with_input(bench_id(&memory, &shape), &memory, |b, memory| { + b.iter_batched( + || { + let mut catalog = FaultCatalog::from_circuit(&memory.circuit) + .expect("surface memory circuit should be supported"); + catalog.with_noise(&noise); + catalog + }, + |catalog| black_box(catalog.to_mechanisms()), + BatchSize::SmallInput, + ); + }); + } + + group.finish(); +} + +fn bench_noise_sweeps(c: &mut Criterion) { + let mut group = c.benchmark_group("fault_catalog/noise_sweep"); + + for memory in surface_memory_circuits() { + let shape = catalog_shape(&memory.circuit); + let id = bench_label(&memory, &shape); + group.throughput(Throughput::Elements(as_u64( + shape.locations * SWEEP_NOISES.len(), + ))); + + group.bench_with_input( + BenchmarkId::new("direct_catalog_sweep", id.clone()), + &memory, + |b, memory| { + b.iter(|| { + let mut total_locations = 0usize; + let mut total_alternatives = 0usize; + for noise in SWEEP_NOISES { + let catalog = build_fault_catalog(black_box(&memory.circuit), noise) + .expect("surface memory circuit should be supported"); + total_locations += catalog.locations.len(); + total_alternatives += count_alternatives(&catalog); + } + black_box((total_locations, total_alternatives)) + }); + }, + ); + + group.bench_with_input( + BenchmarkId::new("parameterized_catalog_sweep", id.clone()), + &memory, + |b, memory| { + b.iter(|| { + let structural = FaultCatalog::from_circuit(black_box(&memory.circuit)) + .expect("surface memory circuit should be supported"); + let mut total_locations = 0usize; + let mut total_alternatives = 0usize; + for noise in SWEEP_NOISES { + let catalog = structural.parameterized(noise); + total_locations += catalog.locations.len(); + total_alternatives += count_alternatives(&catalog); + } + black_box((total_locations, total_alternatives)) + }); + }, + ); + + group.bench_with_input( + BenchmarkId::new("direct_raw_mechanism_sweep", id.clone()), + &memory, + |b, memory| { + b.iter(|| { + let mut total_mechanisms = 0usize; + let mut total_alternatives = 0usize; + for noise in SWEEP_NOISES { + let mechanisms = build_fault_table(black_box(&memory.circuit), noise) + .expect("surface memory circuit should be supported"); + total_mechanisms += mechanisms.len(); + total_alternatives += mechanisms + .iter() + .map(|mechanism| mechanism.alternatives.len()) + .sum::(); + } + black_box((total_mechanisms, total_alternatives)) + }); + }, + ); + + group.bench_with_input( + BenchmarkId::new("parameterized_raw_mechanism_sweep", id), + &memory, + |b, memory| { + b.iter(|| { + let structural = FaultCatalog::from_circuit(black_box(&memory.circuit)) + .expect("surface memory circuit should be supported"); + let mut total_mechanisms = 0usize; + let mut total_alternatives = 0usize; + for noise in SWEEP_NOISES { + let catalog = structural.parameterized(noise); + let mechanisms = catalog.to_mechanisms(); + total_mechanisms += mechanisms.len(); + total_alternatives += mechanisms + .iter() + .map(|mechanism| mechanism.alternatives.len()) + .sum::(); + } + black_box((total_mechanisms, total_alternatives)) + }); + }, + ); + } + + group.finish(); +} + +fn surface_memory_circuits() -> Vec { + DISTANCES + .iter() + .map(|&distance| { + build_rotated_z_memory_circuit(distance, distance) + .expect("surface memory circuit should build") + }) + .collect() +} + +fn representative_noise() -> StochasticNoiseParams { + StochasticNoiseParams { + p1: 0.0001, + p2: 0.001, + p_meas: 0.001, + p_prep: 0.001, + } +} + +fn bench_id(memory: &MemoryCircuit, shape: &CatalogShape) -> BenchmarkId { + BenchmarkId::from_parameter(bench_label(memory, shape)) +} + +fn bench_label(memory: &MemoryCircuit, shape: &CatalogShape) -> String { + format!( + "d{}_r{}_m{}_det{}_obs{}_loc{}_alt{}", + memory.distance, + memory.rounds, + memory.num_measurements, + memory.num_detectors, + memory.num_observables, + shape.locations, + shape.alternatives, + ) +} + +fn catalog_shape(circuit: &TickCircuit) -> CatalogShape { + let catalog = + FaultCatalog::from_circuit(circuit).expect("surface memory circuit should be supported"); + CatalogShape { + locations: catalog.locations.len(), + alternatives: count_alternatives(&catalog), + } +} + +fn count_alternatives(catalog: &FaultCatalog) -> usize { + catalog + .locations + .iter() + .map(|location| location.faults.len()) + .sum() +} + +fn build_rotated_z_memory_circuit(distance: usize, rounds: usize) -> Result { + let code = SurfaceCode::rotated(distance)?; + let num_data = code.num_data_qubits(); + let x_ancilla_offset = num_data; + let z_ancilla_offset = x_ancilla_offset + code.num_x_stabilizers(); + + let x_ancilla = |idx: usize| x_ancilla_offset + idx; + let z_ancilla = |idx: usize| z_ancilla_offset + idx; + + let mut circuit = TickCircuit::new(); + let data_qubits: Vec = (0..num_data).collect(); + circuit.tick().pz(&data_qubits); + + let mut x_round_measurements: Vec> = Vec::with_capacity(rounds); + let mut z_round_measurements: Vec> = Vec::with_capacity(rounds); + + for _round in 0..rounds { + let x_ancillas: Vec = (0..code.num_x_stabilizers()).map(x_ancilla).collect(); + let z_ancillas: Vec = (0..code.num_z_stabilizers()).map(z_ancilla).collect(); + + circuit.tick().pz(&x_ancillas); + circuit.tick().pz(&z_ancillas); + circuit.tick().h(&x_ancillas); + + for check in code.x_stabilizers() { + let ancilla = x_ancilla(check.index); + for data in check.qubits() { + circuit.tick().cx(&[(ancilla, data)]); + } + } + + for check in code.z_stabilizers() { + let ancilla = z_ancilla(check.index); + for data in check.qubits() { + circuit.tick().cx(&[(data, ancilla)]); + } + } + + circuit.tick().h(&x_ancillas); + + let x_refs = circuit.tick().mz(&x_ancillas); + let z_refs = circuit.tick().mz(&z_ancillas); + x_round_measurements.push(x_refs); + z_round_measurements.push(z_refs); + } + + let final_data_measurements = circuit.tick().mz(&data_qubits); + let num_measurements = circuit.num_measurements(); + + let mut detectors: Vec> = Vec::new(); + + for &meas_ref in z_round_measurements[0] + .iter() + .take(code.num_z_stabilizers()) + { + detectors.push(relative_records(num_measurements, &[meas_ref])); + } + + for round in 1..rounds { + for (¤t, &previous) in x_round_measurements[round] + .iter() + .zip(x_round_measurements[round - 1].iter()) + .take(code.num_x_stabilizers()) + { + detectors.push(relative_records(num_measurements, &[current, previous])); + } + for (¤t, &previous) in z_round_measurements[round] + .iter() + .zip(z_round_measurements[round - 1].iter()) + .take(code.num_z_stabilizers()) + { + detectors.push(relative_records(num_measurements, &[current, previous])); + } + } + + let last_round = rounds - 1; + for check in code.z_stabilizers() { + let mut refs = vec![z_round_measurements[last_round][check.index]]; + refs.extend( + check + .qubits() + .into_iter() + .map(|q| final_data_measurements[q]), + ); + detectors.push(relative_records(num_measurements, &refs)); + } + + let logical_z_refs: Vec = code + .logical_z() + .data_qubits + .iter() + .map(|&q| final_data_measurements[q]) + .collect(); + let observables = vec![relative_records(num_measurements, &logical_z_refs)]; + + circuit.set_meta( + "num_measurements", + Attribute::String(num_measurements.to_string()), + ); + circuit.set_meta("detectors", Attribute::String(records_json(&detectors))); + circuit.set_meta("observables", Attribute::String(records_json(&observables))); + + Ok(MemoryCircuit { + circuit, + distance, + rounds, + num_measurements, + num_detectors: detectors.len(), + num_observables: observables.len(), + }) +} + +fn relative_records(num_measurements: usize, refs: &[TickMeasRef]) -> Vec { + let num_measurements = i32::try_from(num_measurements).expect("measurement count fits in i32"); + refs.iter() + .map(|meas_ref| { + i32::try_from(meas_ref.record_idx).expect("measurement record index fits in i32") + - num_measurements + }) + .collect() +} + +fn records_json(records: &[Vec]) -> String { + let entries: Vec = records + .iter() + .map(|records| { + let values = records + .iter() + .map(i32::to_string) + .collect::>() + .join(","); + format!(r#"{{"records":[{values}]}}"#) + }) + .collect(); + format!("[{}]", entries.join(",")) +} + +fn as_u64(value: usize) -> u64 { + u64::try_from(value).expect("benchmark size fits in u64") +} diff --git a/crates/pecos-core/src/channel.rs b/crates/pecos-core/src/channel.rs new file mode 100644 index 000000000..652d8464c --- /dev/null +++ b/crates/pecos-core/src/channel.rs @@ -0,0 +1,291 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License.You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Symbolic quantum-channel namespace. +//! +//! Constructors in this module return [`ChannelExpr`]. Use this namespace for +//! physical noise, open-system maps, and other CPTP processes: +//! +//! ``` +//! use pecos_core::channel::*; +//! +//! let noise = Depolarizing(0.001, 0) & BitFlip(0.01, 1); +//! ``` +//! +//! Ideal gates can be lifted into this level with [`from_gate`]. Unitary +//! operations and ideal gates are not noise, but they are valid channels when a +//! channel-level expression is needed. + +use crate::op::Op; +use crate::{GateExpr, PauliString, QubitId, UnitaryRep, op}; +use std::ops::{BitAnd, Mul}; + +pub use crate::op::ChannelExpr; + +fn channel_from_op(op: Op) -> ChannelExpr { + op.into_channel() +} + +/// Lifts a unitary expression to the channel level. +#[must_use] +pub fn from_unitary(unitary: impl Into) -> ChannelExpr { + ChannelExpr::Unitary(unitary.into()) +} + +/// Lifts an ideal gate expression to the channel level. +#[must_use] +pub fn from_gate(gate: impl Into) -> ChannelExpr { + ChannelExpr::Gate(gate.into()) +} + +impl From for ChannelExpr { + fn from(unitary: UnitaryRep) -> Self { + ChannelExpr::Unitary(unitary) + } +} + +impl From for ChannelExpr { + fn from(pauli: PauliString) -> Self { + ChannelExpr::Unitary(UnitaryRep::from(pauli)) + } +} + +impl From for ChannelExpr { + fn from(gate: GateExpr) -> Self { + ChannelExpr::Gate(gate) + } +} + +/// Single-qubit depolarizing channel. +#[allow(non_snake_case)] +#[must_use] +pub fn Depolarizing(p: f64, qubit: impl Into) -> ChannelExpr { + channel_from_op(op::Depolarizing(p, qubit)) +} + +/// Dephasing channel. +#[allow(non_snake_case)] +#[must_use] +pub fn Dephasing(p: f64, qubit: impl Into) -> ChannelExpr { + channel_from_op(op::Dephasing(p, qubit)) +} + +/// Bit-flip channel. +#[allow(non_snake_case)] +#[must_use] +pub fn BitFlip(p: f64, qubit: impl Into) -> ChannelExpr { + channel_from_op(op::BitFlip(p, qubit)) +} + +/// Bit-phase-flip channel. +#[allow(non_snake_case)] +#[must_use] +pub fn BitPhaseFlip(p: f64, qubit: impl Into) -> ChannelExpr { + channel_from_op(op::BitPhaseFlip(p, qubit)) +} + +/// General single-qubit Pauli channel. +#[allow(non_snake_case)] +#[must_use] +pub fn PauliChannel(px: f64, py: f64, pz: f64, qubit: impl Into) -> ChannelExpr { + channel_from_op(op::PauliChannel(px, py, pz, qubit)) +} + +/// Two-qubit depolarizing channel. +#[allow(non_snake_case)] +#[must_use] +pub fn Depolarizing2(p: f64, q0: impl Into, q1: impl Into) -> ChannelExpr { + channel_from_op(op::Depolarizing2(p, q0, q1)) +} + +/// Amplitude damping channel. +#[allow(non_snake_case)] +#[must_use] +pub fn AmplitudeDamping(gamma: f64, qubit: impl Into) -> ChannelExpr { + channel_from_op(op::AmplitudeDamping(gamma, qubit)) +} + +/// Phase damping channel. +#[allow(non_snake_case)] +#[must_use] +pub fn PhaseDamping(lambda: f64, qubit: impl Into) -> ChannelExpr { + channel_from_op(op::PhaseDamping(lambda, qubit)) +} + +/// Erasure channel. +#[allow(non_snake_case)] +#[must_use] +pub fn Erasure(prob: f64, qubit: impl Into) -> ChannelExpr { + channel_from_op(op::Erasure(prob, qubit)) +} + +/// Leakage channel. +#[allow(non_snake_case)] +#[must_use] +pub fn Leakage(rate: f64, qubit: impl Into) -> ChannelExpr { + channel_from_op(op::Leakage(rate, qubit)) +} + +impl BitAnd for ChannelExpr { + type Output = ChannelExpr; + + fn bitand(self, rhs: ChannelExpr) -> ChannelExpr { + ChannelExpr::Tensor(vec![self, rhs]) + } +} + +impl BitAnd<&ChannelExpr> for ChannelExpr { + type Output = ChannelExpr; + + fn bitand(self, rhs: &ChannelExpr) -> ChannelExpr { + self & rhs.clone() + } +} + +impl BitAnd for &ChannelExpr { + type Output = ChannelExpr; + + fn bitand(self, rhs: ChannelExpr) -> ChannelExpr { + self.clone() & rhs + } +} + +impl BitAnd<&ChannelExpr> for &ChannelExpr { + type Output = ChannelExpr; + + fn bitand(self, rhs: &ChannelExpr) -> ChannelExpr { + self.clone() & rhs.clone() + } +} + +impl BitAnd for ChannelExpr { + type Output = ChannelExpr; + + fn bitand(self, rhs: GateExpr) -> ChannelExpr { + self & ChannelExpr::Gate(rhs) + } +} + +impl BitAnd for GateExpr { + type Output = ChannelExpr; + + fn bitand(self, rhs: ChannelExpr) -> ChannelExpr { + ChannelExpr::Gate(self) & rhs + } +} + +impl Mul for ChannelExpr { + type Output = ChannelExpr; + + fn mul(self, rhs: ChannelExpr) -> ChannelExpr { + ChannelExpr::Compose(vec![self, rhs]) + } +} + +impl Mul<&ChannelExpr> for ChannelExpr { + type Output = ChannelExpr; + + fn mul(self, rhs: &ChannelExpr) -> ChannelExpr { + self * rhs.clone() + } +} + +impl Mul for &ChannelExpr { + type Output = ChannelExpr; + + fn mul(self, rhs: ChannelExpr) -> ChannelExpr { + self.clone() * rhs + } +} + +impl Mul<&ChannelExpr> for &ChannelExpr { + type Output = ChannelExpr; + + fn mul(self, rhs: &ChannelExpr) -> ChannelExpr { + self.clone() * rhs.clone() + } +} + +impl Mul for ChannelExpr { + type Output = ChannelExpr; + + fn mul(self, rhs: GateExpr) -> ChannelExpr { + self * ChannelExpr::Gate(rhs) + } +} + +impl Mul for GateExpr { + type Output = ChannelExpr; + + fn mul(self, rhs: ChannelExpr) -> ChannelExpr { + ChannelExpr::Gate(self) * rhs + } +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::gate; + + #[test] + fn noise_constructors_return_channel_expr() { + assert!(matches!(Depolarizing(0.1, 0), ChannelExpr::MixedUnitary(_))); + assert!(matches!(Dephasing(0.1, 0), ChannelExpr::MixedUnitary(_))); + assert!(matches!(BitFlip(0.1, 0), ChannelExpr::MixedUnitary(_))); + assert!(matches!(BitPhaseFlip(0.1, 0), ChannelExpr::MixedUnitary(_))); + assert!(matches!( + PauliChannel(0.1, 0.2, 0.3, 0), + ChannelExpr::MixedUnitary(_) + )); + assert!(matches!( + Depolarizing2(0.1, 0, 1), + ChannelExpr::MixedUnitary(_) + )); + assert!(matches!( + AmplitudeDamping(0.1, 0), + ChannelExpr::AmplitudeDamping { .. } + )); + assert!(matches!( + PhaseDamping(0.1, 0), + ChannelExpr::PhaseDamping { .. } + )); + assert!(matches!(Erasure(0.1, 0), ChannelExpr::Erasure { .. })); + assert!(matches!(Leakage(0.1, 0), ChannelExpr::Leakage { .. })); + } + + #[test] + fn ideal_gate_lifts_to_channel_expr() { + let channel = from_gate(gate::MZ(0)); + assert!(matches!( + channel, + ChannelExpr::Gate(GateExpr::Measure { .. }) + )); + } + + #[test] + fn channel_tensor_and_composition_stay_channel_level() { + let tensor = Depolarizing(0.1, 0) & BitFlip(0.2, 1); + assert!(matches!(tensor, ChannelExpr::Tensor(parts) if parts.len() == 2)); + + let sequence = AmplitudeDamping(0.1, 0) * PhaseDamping(0.2, 0); + assert!(matches!(sequence, ChannelExpr::Compose(parts) if parts.len() == 2)); + } + + #[test] + fn gate_channel_combinations_promote_to_channel_level() { + let tensor = gate::H(0) & Depolarizing(0.1, 1); + assert!(matches!(tensor, ChannelExpr::Tensor(parts) if parts.len() == 2)); + + let sequence = Depolarizing(0.1, 0) * gate::MZ(0); + assert!(matches!(sequence, ChannelExpr::Compose(parts) if parts.len() == 2)); + } +} diff --git a/crates/pecos-core/src/gate.rs b/crates/pecos-core/src/gate.rs new file mode 100644 index 000000000..5db52bcea --- /dev/null +++ b/crates/pecos-core/src/gate.rs @@ -0,0 +1,472 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License.You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Ideal circuit-operation namespace. +//! +//! Constructors in this module return [`GateExpr`]. Use this namespace when +//! the operation is an intended ideal circuit operation, including unitary +//! gates, preparation, measurement, and reset: +//! +//! ``` +//! use pecos_core::gate::*; +//! +//! let layer = H(0) & MZ(1); +//! let sequence = PZ(0) * H(0) * MZ(0); +//! ``` +//! +//! For automatic promotion across all levels, use [`crate::op`]. For physical +//! noise and open-system maps, use [`crate::channel`]. + +use crate::op::Op; +use crate::unitary_rep::{QubitPairs, Qubits}; +use crate::{Angle64, PauliString, QubitId, UnitaryRep, op, unitary_rep}; +use std::ops::{BitAnd, Mul}; + +pub use crate::op::{Basis, GateExpr}; + +fn gate_from_op(op: Op) -> GateExpr { + op.into_gate() + .expect("gate namespace constructors are gate-convertible") +} + +/// Lifts a unitary expression to the ideal gate level. +#[must_use] +pub fn from_unitary(unitary: impl Into) -> GateExpr { + GateExpr::Unitary(unitary.into()) +} + +impl From for GateExpr { + fn from(unitary: UnitaryRep) -> Self { + GateExpr::Unitary(unitary) + } +} + +impl From for GateExpr { + fn from(pauli: PauliString) -> Self { + GateExpr::Unitary(UnitaryRep::from(pauli)) + } +} + +macro_rules! unitary_1q { + ($name:ident) => { + #[allow(non_snake_case)] + #[must_use] + pub fn $name(qubit: impl Into) -> GateExpr { + from_unitary(unitary_rep::$name(qubit)) + } + }; +} + +macro_rules! unitary_1q_plural { + ($name:ident) => { + #[allow(non_snake_case)] + #[must_use] + pub fn $name(qubits: impl Into) -> GateExpr { + from_unitary(unitary_rep::$name(qubits)) + } + }; +} + +macro_rules! op_1q { + ($name:ident) => { + #[allow(non_snake_case)] + #[must_use] + pub fn $name(qubit: impl Into) -> GateExpr { + gate_from_op(op::$name(qubit)) + } + }; +} + +macro_rules! op_2q { + ($name:ident) => { + #[allow(non_snake_case)] + #[must_use] + pub fn $name(q0: impl Into, q1: impl Into) -> GateExpr { + gate_from_op(op::$name(q0, q1)) + } + }; +} + +macro_rules! unitary_2q { + ($name:ident) => { + #[allow(non_snake_case)] + #[must_use] + pub fn $name(q0: impl Into, q1: impl Into) -> GateExpr { + from_unitary(unitary_rep::$name(q0, q1)) + } + }; +} + +macro_rules! unitary_2q_plural { + ($name:ident) => { + #[allow(non_snake_case)] + #[must_use] + pub fn $name(pairs: impl Into) -> GateExpr { + from_unitary(unitary_rep::$name(pairs)) + } + }; +} + +unitary_1q!(I); +unitary_1q_plural!(Is); +unitary_1q!(X); +unitary_1q_plural!(Xs); +unitary_1q!(Y); +unitary_1q_plural!(Ys); +unitary_1q!(Z); +unitary_1q_plural!(Zs); +unitary_1q!(H); +unitary_1q_plural!(Hs); +unitary_1q!(SX); +unitary_1q_plural!(SXs); +op_1q!(SXdg); +unitary_1q!(SY); +unitary_1q_plural!(SYs); +op_1q!(SYdg); +unitary_1q!(SZ); +unitary_1q_plural!(SZs); +op_1q!(SZdg); +op_1q!(H2); +op_1q!(H3); +op_1q!(H4); +op_1q!(H5); +op_1q!(H6); +op_1q!(F); +op_1q!(Fdg); +op_1q!(F2); +op_1q!(F2dg); +op_1q!(F3); +op_1q!(F3dg); +op_1q!(F4); +op_1q!(F4dg); +unitary_1q!(T); +unitary_1q_plural!(Ts); +op_1q!(Tdg); + +unitary_2q!(CX); +unitary_2q_plural!(CXs); +unitary_2q!(CY); +unitary_2q_plural!(CYs); +unitary_2q!(CZ); +unitary_2q_plural!(CZs); +unitary_2q!(SWAP); +unitary_2q_plural!(SWAPs); +op_2q!(SXX); +op_2q!(SXXdg); +op_2q!(SYY); +op_2q!(SYYdg); +unitary_2q!(SZZ); +unitary_2q_plural!(SZZs); +op_2q!(SZZdg); +op_2q!(ISWAP); +op_2q!(ISWAPdg); +op_2q!(G); +op_2q!(Gdg); + +/// Rotation around X axis: exp(-i theta/2 X). +#[allow(non_snake_case)] +#[must_use] +pub fn RX(angle: Angle64, qubit: impl Into) -> GateExpr { + from_unitary(unitary_rep::RX(angle, qubit)) +} + +/// Rotations around X on multiple qubits. +#[allow(non_snake_case)] +#[must_use] +pub fn RXs(angle: Angle64, qubits: impl Into) -> GateExpr { + from_unitary(unitary_rep::RXs(angle, qubits)) +} + +/// Rotation around Y axis: exp(-i theta/2 Y). +#[allow(non_snake_case)] +#[must_use] +pub fn RY(angle: Angle64, qubit: impl Into) -> GateExpr { + from_unitary(unitary_rep::RY(angle, qubit)) +} + +/// Rotations around Y on multiple qubits. +#[allow(non_snake_case)] +#[must_use] +pub fn RYs(angle: Angle64, qubits: impl Into) -> GateExpr { + from_unitary(unitary_rep::RYs(angle, qubits)) +} + +/// Rotation around Z axis: exp(-i theta/2 Z). +#[allow(non_snake_case)] +#[must_use] +pub fn RZ(angle: Angle64, qubit: impl Into) -> GateExpr { + from_unitary(unitary_rep::RZ(angle, qubit)) +} + +/// Rotations around Z on multiple qubits. +#[allow(non_snake_case)] +#[must_use] +pub fn RZs(angle: Angle64, qubits: impl Into) -> GateExpr { + from_unitary(unitary_rep::RZs(angle, qubits)) +} + +/// Two-qubit XX rotation: exp(-i theta/2 XX). +#[allow(non_snake_case)] +#[must_use] +pub fn RXX(angle: Angle64, q0: impl Into, q1: impl Into) -> GateExpr { + from_unitary(unitary_rep::RXX(angle, q0, q1)) +} + +/// XX rotations on multiple qubit pairs. +#[allow(non_snake_case)] +#[must_use] +pub fn RXXs(angle: Angle64, pairs: impl Into) -> GateExpr { + from_unitary(unitary_rep::RXXs(angle, pairs)) +} + +/// Two-qubit YY rotation: exp(-i theta/2 YY). +#[allow(non_snake_case)] +#[must_use] +pub fn RYY(angle: Angle64, q0: impl Into, q1: impl Into) -> GateExpr { + from_unitary(unitary_rep::RYY(angle, q0, q1)) +} + +/// YY rotations on multiple qubit pairs. +#[allow(non_snake_case)] +#[must_use] +pub fn RYYs(angle: Angle64, pairs: impl Into) -> GateExpr { + from_unitary(unitary_rep::RYYs(angle, pairs)) +} + +/// Two-qubit ZZ rotation: exp(-i theta/2 ZZ). +#[allow(non_snake_case)] +#[must_use] +pub fn RZZ(angle: Angle64, q0: impl Into, q1: impl Into) -> GateExpr { + from_unitary(unitary_rep::RZZ(angle, q0, q1)) +} + +/// ZZ rotations on multiple qubit pairs. +#[allow(non_snake_case)] +#[must_use] +pub fn RZZs(angle: Angle64, pairs: impl Into) -> GateExpr { + from_unitary(unitary_rep::RZZs(angle, pairs)) +} + +/// Toffoli gate (CCX). +#[allow(non_snake_case)] +#[must_use] +pub fn CCX(c0: impl Into, c1: impl Into, target: impl Into) -> GateExpr { + from_unitary(unitary_rep::CCX(c0, c1, target)) +} + +/// Prepare a qubit in the requested basis eigenstate. +#[must_use] +pub fn prep(basis: Basis, qubit: impl Into) -> GateExpr { + GateExpr::Prep { + basis, + qubit: qubit.into().0, + } +} + +/// Measure a qubit in the requested basis. +#[must_use] +pub fn measure(basis: Basis, qubit: impl Into) -> GateExpr { + GateExpr::Measure { + basis, + qubit: qubit.into().0, + } +} + +/// Reset a qubit to the requested basis eigenstate. +#[must_use] +pub fn reset(basis: Basis, qubit: impl Into) -> GateExpr { + GateExpr::Reset { + basis, + qubit: qubit.into().0, + } +} + +/// Prepare qubit in the |0> state. +#[allow(non_snake_case)] +#[must_use] +pub fn PZ(qubit: impl Into) -> GateExpr { + prep(Basis::Z, qubit) +} + +/// Prepare qubit in the |+> state. +#[allow(non_snake_case)] +#[must_use] +pub fn PX(qubit: impl Into) -> GateExpr { + prep(Basis::X, qubit) +} + +/// Prepare qubit in the Y-basis +1 eigenstate. +#[allow(non_snake_case)] +#[must_use] +pub fn PY(qubit: impl Into) -> GateExpr { + prep(Basis::Y, qubit) +} + +/// Measure qubit in the Z basis. +#[allow(non_snake_case)] +#[must_use] +pub fn MZ(qubit: impl Into) -> GateExpr { + measure(Basis::Z, qubit) +} + +/// Measure qubit in the X basis. +#[allow(non_snake_case)] +#[must_use] +pub fn MX(qubit: impl Into) -> GateExpr { + measure(Basis::X, qubit) +} + +/// Measure qubit in the Y basis. +#[allow(non_snake_case)] +#[must_use] +pub fn MY(qubit: impl Into) -> GateExpr { + measure(Basis::Y, qubit) +} + +/// Reset qubit to |0>. +#[allow(non_snake_case)] +#[must_use] +pub fn Reset(qubit: impl Into) -> GateExpr { + reset(Basis::Z, qubit) +} + +impl BitAnd for GateExpr { + type Output = GateExpr; + + fn bitand(self, rhs: GateExpr) -> GateExpr { + GateExpr::Tensor(vec![self, rhs]) + } +} + +impl BitAnd<&GateExpr> for GateExpr { + type Output = GateExpr; + + fn bitand(self, rhs: &GateExpr) -> GateExpr { + self & rhs.clone() + } +} + +impl BitAnd for &GateExpr { + type Output = GateExpr; + + fn bitand(self, rhs: GateExpr) -> GateExpr { + self.clone() & rhs + } +} + +impl BitAnd<&GateExpr> for &GateExpr { + type Output = GateExpr; + + fn bitand(self, rhs: &GateExpr) -> GateExpr { + self.clone() & rhs.clone() + } +} + +impl Mul for GateExpr { + type Output = GateExpr; + + fn mul(self, rhs: GateExpr) -> GateExpr { + GateExpr::Compose(vec![self, rhs]) + } +} + +impl Mul<&GateExpr> for GateExpr { + type Output = GateExpr; + + fn mul(self, rhs: &GateExpr) -> GateExpr { + self * rhs.clone() + } +} + +impl Mul for &GateExpr { + type Output = GateExpr; + + fn mul(self, rhs: GateExpr) -> GateExpr { + self.clone() * rhs + } +} + +impl Mul<&GateExpr> for &GateExpr { + type Output = GateExpr; + + fn mul(self, rhs: &GateExpr) -> GateExpr { + self.clone() * rhs.clone() + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn namespace_constructors_return_gate_expr() { + assert!(matches!( + MZ(3), + GateExpr::Measure { + basis: Basis::Z, + qubit: 3 + } + )); + assert!(matches!( + MX(4), + GateExpr::Measure { + basis: Basis::X, + qubit: 4 + } + )); + assert!(matches!( + MY(5), + GateExpr::Measure { + basis: Basis::Y, + qubit: 5 + } + )); + assert!(matches!( + PZ(0), + GateExpr::Prep { + basis: Basis::Z, + qubit: 0 + } + )); + assert!(matches!( + PX(1), + GateExpr::Prep { + basis: Basis::X, + qubit: 1 + } + )); + assert!(matches!( + PY(2), + GateExpr::Prep { + basis: Basis::Y, + qubit: 2 + } + )); + } + + #[test] + fn unitary_constructor_lifts_to_gate_level() { + assert!(matches!(H(0), GateExpr::Unitary(_))); + assert!(matches!(T(0), GateExpr::Unitary(_))); + assert!(matches!(CX(0, 1), GateExpr::Unitary(_))); + assert_eq!(I(7).qubits(), vec![7]); + } + + #[test] + fn gate_tensor_and_composition_stay_gate_level() { + let tensor = H(0) & MZ(1); + assert!(matches!(tensor, GateExpr::Tensor(parts) if parts.len() == 2)); + + let sequence = PZ(0) * H(0) * MZ(0); + assert!(matches!(sequence, GateExpr::Compose(parts) if parts.len() == 2)); + } +} diff --git a/crates/pecos-core/src/lib.rs b/crates/pecos-core/src/lib.rs index 32ab6d5b6..800446a0f 100644 --- a/crates/pecos-core/src/lib.rs +++ b/crates/pecos-core/src/lib.rs @@ -98,6 +98,8 @@ pub use circuit_diagram::{ // use pecos_core::pauli::*; // I, X, Y, Z, Xs, Ys, Zs -> PauliString // use pecos_core::clifford::*; // H, CX, CZ, SWAP, ... -> CliffordRep // use pecos_core::unitary::*; // T, RZ, CCX, ... -> UnitaryRep +// use pecos_core::gate::*; // MZ, PZ, Reset, ... -> GateExpr +// use pecos_core::channel::*; // Depolarizing, PauliChannel, ... -> ChannelExpr // use pecos_core::op::*; // MZ, PZ, Depolarizing, ... -> Op (promoted) pub mod unitary; @@ -108,6 +110,8 @@ pub use pauli::constructors::{I, X, Xs, Y, Ys, Z, Zs}; pub mod clifford; pub use clifford::Clifford; +pub mod channel; +pub mod gate; pub mod gate_algebra; pub mod op; diff --git a/crates/pecos-core/src/op.rs b/crates/pecos-core/src/op.rs index 8116dc197..15b8a66c8 100644 --- a/crates/pecos-core/src/op.rs +++ b/crates/pecos-core/src/op.rs @@ -1358,6 +1358,16 @@ pub fn PX(qubit: impl Into) -> Op { }) } +/// Prepare qubit in the Y-basis +1 eigenstate. +#[allow(non_snake_case)] +#[must_use] +pub fn PY(qubit: impl Into) -> Op { + Op::Gate(GateExpr::Prep { + basis: Basis::Y, + qubit: qubit.into().0, + }) +} + /// Measure qubit in the Z basis (computational basis measurement). #[allow(non_snake_case)] #[must_use] @@ -1378,6 +1388,16 @@ pub fn MX(qubit: impl Into) -> Op { }) } +/// Measure qubit in the Y basis. +#[allow(non_snake_case)] +#[must_use] +pub fn MY(qubit: impl Into) -> Op { + Op::Gate(GateExpr::Measure { + basis: Basis::Y, + qubit: qubit.into().0, + }) +} + // --- Noise channel constructors --- /// Single-qubit depolarizing channel: ρ → (1−p)ρ + (p/3)(XρX + `YρY` + `ZρZ`). @@ -2068,8 +2088,10 @@ mod tests { fn gate_level() { assert!(MZ(0).is_gate()); assert!(MX(0).is_gate()); + assert!(MY(0).is_gate()); assert!(PZ(0).is_gate()); assert!(PX(0).is_gate()); + assert!(PY(0).is_gate()); } #[test] @@ -2345,6 +2367,28 @@ mod tests { let op = Reset(0); assert!(op.is_gate()); assert_eq!(op.qubits(), vec![0]); + + assert!(matches!( + PX(1), + Op::Gate(GateExpr::Prep { + basis: Basis::X, + qubit: 1 + }) + )); + assert!(matches!( + PY(2), + Op::Gate(GateExpr::Prep { + basis: Basis::Y, + qubit: 2 + }) + )); + assert!(matches!( + PZ(3), + Op::Gate(GateExpr::Prep { + basis: Basis::Z, + qubit: 3 + }) + )); } #[test] diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs index 5671f4c25..d8665379a 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs @@ -189,20 +189,20 @@ impl<'a> DemBuilder<'a> { /// Resolve preparation X-error rate at a specific location. fn init_rate_for_loc(&self, loc: &DagSpacetimeLocation) -> f64 { - if let Some(pg) = &self.per_gate { - if let Some(q) = loc.qubits.first() { - return pg.init_rate_on(*q); - } + if let Some(pg) = &self.per_gate + && let Some(q) = loc.qubits.first() + { + return pg.init_rate_on(*q); } self.noise.p_prep } /// Resolve measurement X-flip rate at a specific location. fn measurement_rate_for_loc(&self, loc: &DagSpacetimeLocation) -> f64 { - if let Some(pg) = &self.per_gate { - if let Some(q) = loc.qubits.first() { - return pg.measurement_rate_on(*q); - } + if let Some(pg) = &self.per_gate + && let Some(q) = loc.qubits.first() + { + return pg.measurement_rate_on(*q); } self.noise.p_meas } @@ -442,25 +442,25 @@ impl<'a> DemBuilder<'a> { for (loc_idx, loc) in locations.iter().enumerate() { match loc.gate_type { - GateType::PZ | GateType::QAlloc => { - if !loc.before && self.init_rate_for_loc(loc) > 0.0 { - self.process_prep_fault_source_tracked( - loc_idx, - dem, - meas_to_detectors, - meas_to_observables, - ); - } + GateType::PZ | GateType::QAlloc + if !loc.before && self.init_rate_for_loc(loc) > 0.0 => + { + self.process_prep_fault_source_tracked( + loc_idx, + dem, + meas_to_detectors, + meas_to_observables, + ); } - GateType::MZ | GateType::MeasureFree => { - if loc.before && self.measurement_rate_for_loc(loc) > 0.0 { - self.process_meas_fault_source_tracked( - loc_idx, - dem, - meas_to_detectors, - meas_to_observables, - ); - } + GateType::MZ | GateType::MeasureFree + if loc.before && self.measurement_rate_for_loc(loc) > 0.0 => + { + self.process_meas_fault_source_tracked( + loc_idx, + dem, + meas_to_detectors, + meas_to_observables, + ); } GateType::CX | GateType::CZ diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index 1d4ef3238..b1815bc5b 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -225,6 +225,16 @@ pub struct SamplingEngine { num_dem_outputs: usize, } +const U32_BASE_AS_F64: f64 = 4_294_967_296.0; +const U64_MAX_AS_F64: f64 = 18_446_744_073_709_551_615.0; + +fn threshold_to_probability(threshold: u64) -> f64 { + let hi = u32::try_from(threshold >> 32).expect("upper threshold word fits in u32"); + let lo = + u32::try_from(threshold & u64::from(u32::MAX)).expect("lower threshold word fits in u32"); + (f64::from(hi) * U32_BASE_AS_F64 + f64::from(lo)) / U64_MAX_AS_F64 +} + impl SamplingEngine { /// Number of mechanisms in the sampler. #[must_use] @@ -253,7 +263,7 @@ impl SamplingEngine { self.num_dem_outputs } - /// Reconstruct a [`DetectorErrorModel`] from the aggregated SoA + /// Reconstruct a [`DetectorErrorModel`] from the aggregated `SoA` /// mechanism state for text output (e.g. Stim-format via /// [`DetectorErrorModel::to_string`]). /// @@ -268,9 +278,8 @@ impl SamplingEngine { pub fn to_detector_error_model(&self) -> super::types::DetectorErrorModel { use super::types::{DetectorErrorModel, FaultMechanism}; let mut dem = DetectorErrorModel::with_capacity(self.num_detectors, self.num_dem_outputs); - let inv_max = 1.0_f64 / u64::MAX as f64; for i in 0..self.thresholds.len() { - let prob = self.thresholds[i] as f64 * inv_max; + let prob = threshold_to_probability(self.thresholds[i]); let det_start = self.detector_offsets[i] as usize; let det_end = self.detector_offsets[i + 1] as usize; let obs_start = self.dem_output_offsets[i] as usize; @@ -1512,23 +1521,25 @@ impl SamplingEngine { /// /// Used to decide between geometric (low p) and SIMD (high p) sampling. #[must_use] - #[allow(clippy::cast_precision_loss)] pub fn average_error_probability(&self) -> f64 { if self.thresholds.is_empty() { return 0.0; } - let sum: u128 = self.thresholds.iter().map(|&t| u128::from(t)).sum(); - let avg_threshold = (sum / self.thresholds.len() as u128) as f64; - avg_threshold / u64::MAX as f64 + let mut sum = 0.0; + let mut count = 0.0; + for &threshold in &self.thresholds { + sum += threshold_to_probability(threshold); + count += 1.0; + } + sum / count } /// Maximum error probability across all mechanisms. #[must_use] - #[allow(clippy::cast_precision_loss)] pub fn max_error_probability(&self) -> f64 { self.thresholds .iter() - .map(|&t| t as f64 / u64::MAX as f64) + .map(|&t| threshold_to_probability(t)) .fold(0.0, f64::max) } @@ -2224,10 +2235,10 @@ impl<'a> SamplingEngineBuilder<'a> { &self, loc: &super::super::propagator::dag::DagSpacetimeLocation, ) -> f64 { - if let Some(pg) = &self.per_gate { - if let Some(q) = loc.qubits.first() { - return pg.init_rate_on(*q); - } + if let Some(pg) = &self.per_gate + && let Some(q) = loc.qubits.first() + { + return pg.init_rate_on(*q); } self.p_prep } @@ -2239,10 +2250,10 @@ impl<'a> SamplingEngineBuilder<'a> { &self, loc: &super::super::propagator::dag::DagSpacetimeLocation, ) -> f64 { - if let Some(pg) = &self.per_gate { - if let Some(q) = loc.qubits.first() { - return pg.measurement_rate_on(*q); - } + if let Some(pg) = &self.per_gate + && let Some(q) = loc.qubits.first() + { + return pg.measurement_rate_on(*q); } self.p_meas } diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/mem_builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/mem_builder.rs index 9c8957187..85176ec4c 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/mem_builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/mem_builder.rs @@ -80,25 +80,11 @@ impl<'a> MemBuilder<'a> { for (loc_idx, loc) in locations.iter().enumerate() { match loc.gate_type { - GateType::PZ | GateType::QAlloc => { - if self.noise.p_prep > 0.0 && !loc.before { - self.process_single_pauli_fault( - loc_idx, - Pauli::X, - self.noise.p_prep, - &mut mem, - ); - } + GateType::PZ | GateType::QAlloc if self.noise.p_prep > 0.0 && !loc.before => { + self.process_single_pauli_fault(loc_idx, Pauli::X, self.noise.p_prep, &mut mem); } - GateType::MZ | GateType::MeasureFree => { - if self.noise.p_meas > 0.0 && loc.before { - self.process_single_pauli_fault( - loc_idx, - Pauli::X, - self.noise.p_meas, - &mut mem, - ); - } + GateType::MZ | GateType::MeasureFree if self.noise.p_meas > 0.0 && loc.before => { + self.process_single_pauli_fault(loc_idx, Pauli::X, self.noise.p_meas, &mut mem); } GateType::CX | GateType::CZ @@ -112,10 +98,10 @@ impl<'a> MemBuilder<'a> { | GateType::SWAP | GateType::RXX | GateType::RYY - | GateType::RZZ => { - if !loc.before { - two_qubit_groups.entry(loc.node).or_default().push(loc_idx); - } + | GateType::RZZ + if !loc.before => + { + two_qubit_groups.entry(loc.node).or_default().push(loc_idx); } GateType::H | GateType::F @@ -135,44 +121,27 @@ impl<'a> MemBuilder<'a> { | GateType::RY | GateType::RZ | GateType::U - | GateType::R1XY => { - if self.noise.p1 > 0.0 && !loc.before { - self.process_single_qubit_fault(loc_idx, &mut mem); - } + | GateType::R1XY + if self.noise.p1 > 0.0 && !loc.before => + { + self.process_single_qubit_fault(loc_idx, &mut mem); } - GateType::Idle => { - if !loc.before { - if self.noise.uses_dedicated_idle_noise() { - #[allow(clippy::cast_precision_loss)] - let duration = loc.idle_duration.max(1) as f64; - let probs = self.noise.idle_pauli_probs(duration); - if probs.px > 0.0 { - self.process_single_pauli_fault( - loc_idx, - Pauli::X, - probs.px, - &mut mem, - ); - } - if probs.py > 0.0 { - self.process_single_pauli_fault( - loc_idx, - Pauli::Y, - probs.py, - &mut mem, - ); - } - if probs.pz > 0.0 { - self.process_single_pauli_fault( - loc_idx, - Pauli::Z, - probs.pz, - &mut mem, - ); - } - } else if self.noise.p1 > 0.0 { - self.process_single_qubit_fault(loc_idx, &mut mem); + GateType::Idle if !loc.before => { + if self.noise.uses_dedicated_idle_noise() { + #[allow(clippy::cast_precision_loss)] + let duration = loc.idle_duration.max(1) as f64; + let probs = self.noise.idle_pauli_probs(duration); + if probs.px > 0.0 { + self.process_single_pauli_fault(loc_idx, Pauli::X, probs.px, &mut mem); + } + if probs.py > 0.0 { + self.process_single_pauli_fault(loc_idx, Pauli::Y, probs.py, &mut mem); } + if probs.pz > 0.0 { + self.process_single_pauli_fault(loc_idx, Pauli::Z, probs.pz, &mut mem); + } + } else if self.noise.p1 > 0.0 { + self.process_single_qubit_fault(loc_idx, &mut mem); } } _ => {} diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs index 92ee29521..57ae442a5 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs @@ -1958,8 +1958,8 @@ pub const PAULI_2Q_ORDER: [&str; 15] = [ /// /// (And analogously for 2Q with `(gate, (q_control, q_target))`.) /// -/// This lets users specify "H on qubit 0 has these rates (high T_1), H on -/// qubit 1 has these (low T_1), every other H uses the per-gate default". +/// This lets users specify "H on qubit 0 has these rates (high `T_1`), H on +/// qubit 1 has these (low `T_1`), every other H uses the per-gate default". /// /// # Integration with `pecos-lindblad` /// @@ -2080,8 +2080,7 @@ impl PerGateTypeNoise { pub fn rate_1q(&self, gate: GateType, pauli_idx: usize) -> f64 { self.rates_1q .get(&gate) - .map(|r| r[pauli_idx]) - .unwrap_or(self.base.p1 / 3.0) + .map_or(self.base.p1 / 3.0, |r| r[pauli_idx]) } /// Lookup 1Q Pauli rate for a gate on a specific qubit. Tries the @@ -2101,8 +2100,7 @@ impl PerGateTypeNoise { pub fn rate_2q(&self, gate: GateType, pair_idx: usize) -> f64 { self.rates_2q .get(&gate) - .map(|r| r[pair_idx]) - .unwrap_or(self.base.p2 / 15.0) + .map_or(self.base.p2 / 15.0, |r| r[pair_idx]) } /// Lookup 2Q Pauli pair rate for a gate on a specific ordered diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index 70ac83b45..80c321b81 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -36,10 +36,9 @@ use pecos_core::pauli::pauli_string::PauliString; use pecos_core::{Pauli, QubitId}; use pecos_quantum::{AnnotationKind, TickCircuit}; use pecos_random::{PecosRng, RngExt}; -use pecos_simulators::CliffordGateable; use pecos_simulators::measurement_sampler::{MeasurementKind, SampleResult}; -use pecos_simulators::pauli_prop::PauliProp; use pecos_simulators::symbolic_sparse_stab::MeasurementHistory; +use pecos_simulators::{BitmaskPauliProp, CliffordGateable}; use std::collections::{BTreeSet, HashMap}; use std::fmt; @@ -317,7 +316,7 @@ pub(crate) fn propagate_single( gates: &[GateLoc], meas_positions: &HashMap, ) -> BTreeSet { - let mut prop = PauliProp::new(); + let mut prop = BitmaskPauliProp::new(); match pauli { PauliType::X => prop.track_x(&[qubit]), PauliType::Y => prop.track_y(&[qubit]), @@ -335,7 +334,7 @@ fn propagate_single_effect( meas_positions: &HashMap, tracked_ops: &[PauliString], ) -> PropagatedFaultEffect { - let mut prop = PauliProp::new(); + let mut prop = BitmaskPauliProp::new(); match pauli { PauliType::X => prop.track_x(&[qubit]), PauliType::Y => prop.track_y(&[qubit]), @@ -357,7 +356,7 @@ fn propagate_pair_effect( meas_positions: &HashMap, tracked_ops: &[PauliString], ) -> PropagatedFaultEffect { - let mut prop = PauliProp::new(); + let mut prop = BitmaskPauliProp::new(); for (pauli, qubit) in faults { match pauli { PauliType::X => prop.track_x(&[qubit]), @@ -381,7 +380,7 @@ struct PropagatedFaultEffect { /// Core forward propagation: evolve a Pauli through gates, collecting affected measurements. fn propagate_forward( - prop: &mut PauliProp, + prop: &mut BitmaskPauliProp, start: usize, gates: &[GateLoc], meas_positions: &HashMap, @@ -475,6 +474,10 @@ fn propagate_forward( } _ => {} } + + if prop.is_identity() { + break; + } } affected @@ -988,6 +991,7 @@ fn build_structural_fault_catalog(tc: &TickCircuit) -> Result Result Result Result Result Result Result { if let Some(&meas_idx) = meas_positions.get(&loc_idx) { let affected = vec![meas_idx]; - let dets = measurements_to_detectors(&affected, &det_records, num_meas); - let obs = measurements_to_observables(&affected, &obs_records, num_meas); + let dets = record_effect_index.detectors_for_measurements(&affected); + let obs = record_effect_index.observables_for_measurements(&affected); locations.push(FaultLocation { tick: tick_idx, gate_index: gate_idx, @@ -1298,7 +1302,7 @@ fn parse_tracked_operator_annotations(tc: &TickCircuit) -> Vec { .collect() } -fn tracked_ops_flipped_by(prop: &PauliProp, tracked_ops: &[PauliString]) -> Vec { +fn tracked_ops_flipped_by(prop: &BitmaskPauliProp, tracked_ops: &[PauliString]) -> Vec { tracked_ops .iter() .enumerate() @@ -1355,62 +1359,78 @@ fn record_absolute_index(num_meas: usize, rec: i32) -> Option { usize::try_from(abs_idx).ok() } -/// Map measurement effects to detector effects via record XOR. -fn measurements_to_detectors( - affected_meas: &[usize], - det_records: &[Vec], - num_meas: usize, -) -> Vec { - let mut fired = Vec::new(); - for (det_idx, records) in det_records.iter().enumerate() { - let mut parity = 0u8; +struct RecordEffectIndex { + detectors_by_measurement: Vec>, + observables_by_measurement: Vec>, +} + +impl RecordEffectIndex { + fn new(det_records: &[Vec], obs_records: &[Vec], num_meas: usize) -> Self { + Self { + detectors_by_measurement: records_by_measurement(det_records, num_meas), + observables_by_measurement: records_by_measurement(obs_records, num_meas), + } + } + + /// Map measurement effects to detector effects via record XOR. + fn detectors_for_measurements(&self, affected_meas: &[usize]) -> Vec { + measurements_to_record_effects(affected_meas, &self.detectors_by_measurement) + } + + /// Map measurement effects to observable effects via record XOR. + fn observables_for_measurements(&self, affected_meas: &[usize]) -> Vec { + measurements_to_record_effects(affected_meas, &self.observables_by_measurement) + } +} + +fn catalog_effect_parts( + effect: PropagatedFaultEffect, + record_effect_index: &RecordEffectIndex, +) -> (Vec, Vec, Vec, Vec) { + let affected: Vec = effect.affected_measurements.into_iter().collect(); + let dets = record_effect_index.detectors_for_measurements(&affected); + let obs = record_effect_index.observables_for_measurements(&affected); + (affected, dets, obs, effect.affected_tracked_ops) +} + +fn records_by_measurement(records_by_output: &[Vec], num_meas: usize) -> Vec> { + let mut by_measurement = vec![Vec::new(); num_meas]; + for (output_idx, records) in records_by_output.iter().enumerate() { for &rec in records { - if let Some(abs_idx) = record_absolute_index(num_meas, rec) - && affected_meas.contains(&abs_idx) + if let Some(meas_idx) = record_absolute_index(num_meas, rec) + && meas_idx < num_meas { - parity ^= 1; + by_measurement[meas_idx].push(output_idx); } } - if parity != 0 { - fired.push(det_idx); - } } - fired + by_measurement } -/// Map measurement effects to observable effects via record XOR. -fn measurements_to_observables( +fn measurements_to_record_effects( affected_meas: &[usize], - obs_records: &[Vec], - num_meas: usize, + outputs_by_measurement: &[Vec], ) -> Vec { let mut fired = Vec::new(); - for (obs_idx, records) in obs_records.iter().enumerate() { - let mut parity = 0u8; - for &rec in records { - if let Some(abs_idx) = record_absolute_index(num_meas, rec) - && affected_meas.contains(&abs_idx) - { - parity ^= 1; + for &meas_idx in affected_meas { + if let Some(outputs) = outputs_by_measurement.get(meas_idx) { + for &output_idx in outputs { + toggle_sorted(&mut fired, output_idx); } } - if parity != 0 { - fired.push(obs_idx); - } } fired } -fn catalog_effect_parts( - effect: PropagatedFaultEffect, - det_records: &[Vec], - obs_records: &[Vec], - num_meas: usize, -) -> (Vec, Vec, Vec, Vec) { - let affected: Vec = effect.affected_measurements.into_iter().collect(); - let dets = measurements_to_detectors(&affected, det_records, num_meas); - let obs = measurements_to_observables(&affected, obs_records, num_meas); - (affected, dets, obs, effect.affected_tracked_ops) +fn toggle_sorted(values: &mut Vec, value: usize) { + match values.binary_search(&value) { + Ok(pos) => { + values.remove(pos); + } + Err(pos) => { + values.insert(pos, value); + } + } } // ============================================================================ @@ -1829,6 +1849,18 @@ mod tests { ); } + #[test] + fn test_record_effect_index_maps_measurement_effects_by_xor() { + let det_records = vec![vec![-1], vec![-2, -1], vec![-1, -1], vec![-4], vec![1]]; + let obs_records = vec![vec![-2], vec![-1, -2]]; + let index = RecordEffectIndex::new(&det_records, &obs_records, 3); + + assert_eq!(index.detectors_for_measurements(&[2]), vec![0, 1]); + assert_eq!(index.detectors_for_measurements(&[1, 2]), vec![0]); + assert_eq!(index.observables_for_measurements(&[1]), vec![0, 1]); + assert_eq!(index.observables_for_measurements(&[1, 2]), vec![0]); + } + /// Build a minimal `TickCircuit`: PZ(0) H(0) CX(0,1) H(0) MZ(0) PZ(0) H(0) CX(0,1) H(0) MZ(0) fn two_round_x_check() -> TickCircuit { let mut tc = TickCircuit::new(); diff --git a/crates/pecos-qec/tests/per_gate_dem_builder_tests.rs b/crates/pecos-qec/tests/per_gate_dem_builder_tests.rs index 968ee0bee..0dbb4775f 100644 --- a/crates/pecos-qec/tests/per_gate_dem_builder_tests.rs +++ b/crates/pecos-qec/tests/per_gate_dem_builder_tests.rs @@ -64,9 +64,7 @@ fn uniform_equivalent_per_gate_matches_scalar_dem() { .lines() .filter(|l| l.starts_with("error(")) .count(), - "scalar and uniform-per-gate should produce identical error-line counts:\nscalar:\n{}\nper_gate:\n{}", - scalar_text, - per_gate_text, + "scalar and uniform-per-gate should produce identical error-line counts:\nscalar:\n{scalar_text}\nper_gate:\n{per_gate_text}", ); } @@ -96,8 +94,7 @@ fn per_gate_override_produces_decomposed_dem_text() { let error_lines = text.lines().filter(|l| l.starts_with("error(")).count(); assert!( error_lines > 0, - "expected per-gate CX rates to produce error lines in decomposed DEM:\n{}", - text, + "expected per-gate CX rates to produce error lines in decomposed DEM:\n{text}", ); } @@ -145,9 +142,7 @@ fn per_qubit_cx_override_changes_dem_probabilities() { let boosted_sum = sum_probs(&boosted.to_string()); assert!( boosted_sum > 2.0 * baseline_sum, - "per-qubit-pair boost should raise probability sum: baseline={} boosted={}", - baseline_sum, - boosted_sum, + "per-qubit-pair boost should raise probability sum: baseline={baseline_sum} boosted={boosted_sum}", ); } @@ -176,8 +171,7 @@ fn idle_locations_contribute_to_dem_text() { let text = dem.to_string(); assert!( text.contains("error("), - "expected idle location to produce an error line:\n{}", - text, + "expected idle location to produce an error line:\n{text}", ); } diff --git a/crates/pecos-qec/tests/per_qubit_measurement_tests.rs b/crates/pecos-qec/tests/per_qubit_measurement_tests.rs index 59a4523c9..aa95c9435 100644 --- a/crates/pecos-qec/tests/per_qubit_measurement_tests.rs +++ b/crates/pecos-qec/tests/per_qubit_measurement_tests.rs @@ -100,8 +100,7 @@ fn per_qubit_measurement_rate_raises_only_targeted_qubit() { (sim_only_q0.average_error_probability() - sim_uniform.average_error_probability()).abs(); assert!( delta < 1e-12, - "per-mech probabilities should match: {}", - delta + "per-mech probabilities should match: {delta}" ); } @@ -163,5 +162,5 @@ fn per_qubit_measurement_path_uses_base_rate_without_overrides() { assert_eq!(sim_per_gate.num_mechanisms(), sim_scalar.num_mechanisms()); let delta = (sim_per_gate.average_error_probability() - sim_scalar.average_error_probability()).abs(); - assert!(delta < 1e-12, "delta {} should be near zero", delta); + assert!(delta < 1e-12, "delta {delta} should be near zero"); } diff --git a/crates/pecos-qec/tests/per_qubit_noise_tests.rs b/crates/pecos-qec/tests/per_qubit_noise_tests.rs index dc957254d..0be609f9c 100644 --- a/crates/pecos-qec/tests/per_qubit_noise_tests.rs +++ b/crates/pecos-qec/tests/per_qubit_noise_tests.rs @@ -22,6 +22,13 @@ use pecos_qec::fault_tolerance::dem_builder::{DemSamplerBuilder, NoiseConfig, Pe use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; use pecos_quantum::{DagCircuit, GateType}; +fn assert_rate_eq(actual: f64, expected: f64) { + assert!( + (actual - expected).abs() < 1e-14, + "expected rate {expected:.16e}, got {actual:.16e}" + ); +} + #[test] fn per_qubit_override_takes_precedence_over_per_gate_type() { // Direct unit test of the lookup layering, independent of DemSampler. @@ -32,13 +39,13 @@ fn per_qubit_override_takes_precedence_over_per_gate_type() { .with_1q_rates_for_qubit(GateType::H, q0, [0.001, 0.002, 0.003]); // qubit 0 has per-qubit override - assert_eq!(cfg.rate_1q_on(GateType::H, q0, 0), 0.001); - assert_eq!(cfg.rate_1q_on(GateType::H, q0, 1), 0.002); - assert_eq!(cfg.rate_1q_on(GateType::H, q0, 2), 0.003); + assert_rate_eq(cfg.rate_1q_on(GateType::H, q0, 0), 0.001); + assert_rate_eq(cfg.rate_1q_on(GateType::H, q0, 1), 0.002); + assert_rate_eq(cfg.rate_1q_on(GateType::H, q0, 2), 0.003); // qubit 1 uses the per-gate-type default. - assert_eq!(cfg.rate_1q_on(GateType::H, q1, 0), 0.01); - assert_eq!(cfg.rate_1q_on(GateType::H, q1, 1), 0.02); + assert_rate_eq(cfg.rate_1q_on(GateType::H, q1, 0), 0.01); + assert_rate_eq(cfg.rate_1q_on(GateType::H, q1, 1), 0.02); // Unregistered gate on qubit 0 uses the per-gate-type default (not set), // then to uniform base.p1/3. @@ -63,11 +70,11 @@ fn per_qubit_2q_override_takes_precedence() { .with_2q_rates_for_qubits(GateType::CX, q0, q1, per_pair); // (q0, q1) uses the specific rates - assert_eq!(cfg.rate_2q_on(GateType::CX, q0, q1, 0), 1e-3); + assert_rate_eq(cfg.rate_2q_on(GateType::CX, q0, q1, 0), 1e-3); // (q2, q3) uses the per-gate-type default. - assert_eq!(cfg.rate_2q_on(GateType::CX, q2, q3, 0), 5e-4); + assert_rate_eq(cfg.rate_2q_on(GateType::CX, q2, q3, 0), 5e-4); // Different ordered pair (q1, q0): NOT the same as (q0, q1). Falls back. - assert_eq!(cfg.rate_2q_on(GateType::CX, q1, q0, 0), 5e-4); + assert_rate_eq(cfg.rate_2q_on(GateType::CX, q1, q0, 0), 5e-4); } fn build_circuit_with_two_cxs() -> DagCircuit { @@ -125,9 +132,7 @@ fn per_qubit_cx_rate_affects_mechanism_probabilities() { let avg_over = overridden.average_error_probability(); assert!( avg_over > 2.0 * avg_base, - "expected per-qubit override to raise avg error >>2x, got base={} over={}", - avg_base, - avg_over, + "expected per-qubit override to raise avg error >>2x, got base={avg_base} over={avg_over}", ); } diff --git a/crates/pecos-qec/tests/stim_dem_export_tests.rs b/crates/pecos-qec/tests/stim_dem_export_tests.rs index c12be12f7..6c6663e6c 100644 --- a/crates/pecos-qec/tests/stim_dem_export_tests.rs +++ b/crates/pecos-qec/tests/stim_dem_export_tests.rs @@ -47,19 +47,13 @@ fn dem_text_export_with_scalar_noise() { // Must contain at least one error mechanism. assert!( text.contains("error("), - "expected 'error(' line in DEM text:\n{}", - text + "expected 'error(' line in DEM text:\n{text}" ); // Must declare the detector and observable. - assert!( - text.contains("detector D0"), - "missing detector D0:\n{}", - text - ); + assert!(text.contains("detector D0"), "missing detector D0:\n{text}"); assert!( text.contains("logical_observable L0") || text.contains("observable_include L0"), - "missing observable decl:\n{}", - text, + "missing observable decl:\n{text}", ); } @@ -85,8 +79,7 @@ fn dem_text_export_with_per_gate_noise() { let error_lines = text.matches("error(").count(); assert!( error_lines > 0, - "expected per-gate-noise path to produce error lines:\n{}", - text, + "expected per-gate-noise path to produce error lines:\n{text}", ); assert!(text.contains("detector D0")); } @@ -131,6 +124,6 @@ fn dem_probabilities_recoverable_from_thresholds() { // Parse the prob inside "error(...)". let inner = line.trim_start_matches("error(").split(')').next().unwrap(); let p: f64 = inner.parse().unwrap(); - assert!(p > 0.0 && p < 1.0, "probability out of range: {}", p); + assert!(p > 0.0 && p < 1.0, "probability out of range: {p}"); } } diff --git a/crates/pecos-quantum/Cargo.toml b/crates/pecos-quantum/Cargo.toml index e34b23dc4..a829dd2b1 100644 --- a/crates/pecos-quantum/Cargo.toml +++ b/crates/pecos-quantum/Cargo.toml @@ -14,6 +14,7 @@ readme = "README.md" [dependencies] pecos-core.workspace = true pecos-num.workspace = true +pecos-random.workspace = true nalgebra.workspace = true num-complex.workspace = true smallvec.workspace = true diff --git a/crates/pecos-quantum/src/channel.rs b/crates/pecos-quantum/src/channel.rs new file mode 100644 index 000000000..d422e7749 --- /dev/null +++ b/crates/pecos-quantum/src/channel.rs @@ -0,0 +1,2644 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Sparse Pauli-basis channel and operator representations. +//! +//! This module keeps three related representations separate: +//! - [`PauliSum`] stores arbitrary complex coefficients on Pauli operators. +//! - [`PauliChannel`] stores real Pauli error probabilities. +//! - [`DiagonalPtm`] stores real diagonal Pauli-transfer-matrix entries, also +//! called Pauli fidelities for Pauli channels. +//! - [`Ptm`] stores a dense real Pauli-transfer matrix. +//! - [`KrausOps`] stores a concrete Kraus-operator channel representation. +//! - [`ChoiMatrix`] stores a concrete Choi representation. +//! +//! Pauli-channel probabilities and diagonal PTM entries are connected by an +//! explicit Walsh-Hadamard transform. They are not the same representation: +//! probabilities are non-negative and sum to one, while diagonal PTM entries +//! may be negative. + +use std::collections::{BTreeMap, BTreeSet}; +use std::error::Error; +use std::fmt; +use std::ops::{Add, Mul}; + +use nalgebra::{DMatrix, SVD}; +use num_complex::Complex64; +use pecos_core::{ + BitmaskStorage, ChannelExpr, Clifford, Pauli, PauliBitmaskSmall, PauliString, Phase as _, + UnitaryRep, +}; +use pecos_random::{Rng, RngExt as _}; + +use crate::unitary_matrix::to_matrix_with_size; + +const DEFAULT_TOLERANCE: f64 = 1e-12; + +/// Pauli basis ordering used by channel representations. +/// +/// The current PECOS channel basis uses lexicographic Pauli digits with +/// `I=0`, `X=1`, `Y=2`, `Z=3`, and qubit 0 as the least-significant base-4 +/// digit. For two qubits, labels displayed from high qubit to low qubit are: +/// `II, IX, IY, IZ, XI, XX, XY, XZ, ...`. +#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)] +pub enum PtmBasisOrder { + /// Lexicographic Pauli basis with qubit 0 as the fastest-varying digit. + #[default] + LexicographicLittleEndian, +} + +/// Error returned by channel representation constructors and conversions. +#[derive(Debug, Clone, PartialEq)] +pub enum ChannelError { + /// The requested number of qubits would overflow a `usize` dimension. + DimensionOverflow { + /// Number of qubits supplied by the caller. + num_qubits: usize, + }, + /// A value was not a valid Pauli basis digit. + InvalidBasisDigit { + /// Invalid digit. + digit: usize, + }, + /// A Pauli-basis index is outside the basis for the requested qubit count. + BasisIndexOutOfRange { + /// Number of qubits supplied by the caller. + num_qubits: usize, + /// Basis length for that qubit count. + basis_len: usize, + /// Invalid index. + index: usize, + }, + /// A Pauli term acts outside the declared qubit range. + QubitOutOfRange { + /// Number of qubits supplied by the caller. + num_qubits: usize, + /// Highest qubit touched by the offending Pauli term. + qubit: usize, + }, + /// A coefficient or fidelity is not finite. + InvalidCoefficient { + /// Offending coefficient. + value: Complex64, + }, + /// A `PauliSum` coefficient was not real enough for a probability. + NonRealCoefficient { + /// Offending coefficient. + value: Complex64, + /// Allowed imaginary-part tolerance. + tolerance: f64, + }, + /// A probability value is invalid for a Pauli channel. + InvalidProbability { + /// Probability value. + value: f64, + /// Allowed negative tolerance. + tolerance: f64, + }, + /// A probability map does not sum to one within tolerance. + ProbabilitySum { + /// Observed probability sum. + sum: f64, + /// Allowed absolute tolerance. + tolerance: f64, + }, + /// A dense matrix does not match the expected channel or density-matrix + /// shape. + InvalidMatrixShape { + /// Expected row count. + expected_rows: usize, + /// Expected column count. + expected_cols: usize, + /// Actual row count. + rows: usize, + /// Actual column count. + cols: usize, + }, + /// A Kraus channel was constructed without any Kraus operators. + EmptyKrausSet, + /// A numerical matrix decomposition failed. + DecompositionFailed { + /// Human-readable reason. + reason: String, + }, + /// A channel expression is outside the supported conversion subset. + UnsupportedChannelExpr { + /// Human-readable reason. + reason: String, + }, + /// A repeated subsystem was supplied. + DuplicateSubsystem { + /// Repeated qubit/subsystem index. + qubit: usize, + }, +} + +impl fmt::Display for ChannelError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + Self::DimensionOverflow { num_qubits } => write!( + f, + "Pauli-basis dimension overflows usize for {num_qubits} qubits" + ), + Self::InvalidBasisDigit { digit } => write!(f, "invalid Pauli basis digit: {digit}"), + Self::BasisIndexOutOfRange { + num_qubits, + basis_len, + index, + } => write!( + f, + "Pauli-basis index {index} is outside the {basis_len}-element basis for {num_qubits} qubits" + ), + Self::QubitOutOfRange { num_qubits, qubit } => write!( + f, + "Pauli term touches qubit {qubit}, outside declared {num_qubits}-qubit range" + ), + Self::InvalidCoefficient { value } => { + write!(f, "invalid non-finite coefficient: {value}") + } + Self::NonRealCoefficient { value, tolerance } => write!( + f, + "coefficient {value} is not real within tolerance {tolerance}" + ), + Self::InvalidProbability { value, tolerance } => write!( + f, + "invalid Pauli-channel probability {value}; tolerance is {tolerance}" + ), + Self::ProbabilitySum { sum, tolerance } => write!( + f, + "Pauli-channel probabilities must sum to 1 within tolerance {tolerance}, got {sum}" + ), + Self::InvalidMatrixShape { + expected_rows, + expected_cols, + rows, + cols, + } => write!( + f, + "invalid matrix shape {rows}x{cols}; expected {expected_rows}x{expected_cols}" + ), + Self::EmptyKrausSet => write!(f, "Kraus channel must contain at least one operator"), + Self::DecompositionFailed { reason } => { + write!(f, "matrix decomposition failed: {reason}") + } + Self::UnsupportedChannelExpr { reason } => { + write!(f, "unsupported channel expression: {reason}") + } + Self::DuplicateSubsystem { qubit } => { + write!(f, "duplicate subsystem/qubit index: {qubit}") + } + } + } +} + +impl Error for ChannelError {} + +/// Returns the number of Pauli basis elements for `num_qubits`. +/// +/// This is `4^num_qubits`. +/// +/// # Errors +/// +/// Returns [`ChannelError::DimensionOverflow`] when `4^num_qubits` does not +/// fit in `usize`. +pub fn pauli_basis_len(num_qubits: usize) -> Result { + 4usize + .checked_pow( + num_qubits + .try_into() + .map_err(|_| ChannelError::DimensionOverflow { num_qubits })?, + ) + .ok_or(ChannelError::DimensionOverflow { num_qubits }) +} + +/// Maps a Pauli value to the channel-basis digit `I=0, X=1, Y=2, Z=3`. +/// +/// This intentionally differs from the internal [`Pauli`] discriminant order, +/// where `Z` and `Y` are stored in bitmask-friendly order. +#[must_use] +pub fn pauli_to_basis_digit(pauli: Pauli) -> usize { + match pauli { + Pauli::I => 0, + Pauli::X => 1, + Pauli::Y => 2, + Pauli::Z => 3, + } +} + +/// Converts a channel-basis digit to a Pauli value. +/// +/// # Errors +/// +/// Returns [`ChannelError::InvalidBasisDigit`] when `digit` is not in `0..4`. +pub fn basis_digit_to_pauli(digit: usize) -> Result { + match digit { + 0 => Ok(Pauli::I), + 1 => Ok(Pauli::X), + 2 => Ok(Pauli::Y), + 3 => Ok(Pauli::Z), + _ => Err(ChannelError::InvalidBasisDigit { digit }), + } +} + +/// Returns the Pauli basis element at `index`. +/// +/// The returned vector is indexed by qubit number: element 0 is the Pauli on +/// qubit 0. Qubit 0 is the fastest-varying base-4 digit. +/// +/// # Errors +/// +/// Returns an error when `4^num_qubits` overflows or `index` is outside the +/// basis. +pub fn basis_element(num_qubits: usize, index: usize) -> Result, ChannelError> { + let basis_len = pauli_basis_len(num_qubits)?; + if index >= basis_len { + return Err(ChannelError::BasisIndexOutOfRange { + num_qubits, + basis_len, + index, + }); + } + + let mut remaining = index; + let mut paulis = Vec::with_capacity(num_qubits); + for _ in 0..num_qubits { + paulis.push(basis_digit_to_pauli(remaining & 0b11)?); + remaining >>= 2; + } + Ok(paulis) +} + +/// Returns a display label for a Pauli basis element. +/// +/// Labels are printed with the highest-numbered qubit first, matching common +/// ket-label display style. For example, basis index 1 on two qubits is `IX` +/// because it is identity on qubit 1 and X on qubit 0. +/// +/// # Errors +/// +/// Returns an error when `4^num_qubits` overflows or `index` is outside the +/// basis. +pub fn basis_label(num_qubits: usize, index: usize) -> Result { + let paulis = basis_element(num_qubits, index)?; + Ok(paulis + .iter() + .rev() + .map(|pauli| match pauli { + Pauli::I => 'I', + Pauli::X => 'X', + Pauli::Y => 'Y', + Pauli::Z => 'Z', + }) + .collect()) +} + +/// Returns the Pauli bitmask basis element at `index`. +/// +/// # Errors +/// +/// Returns an error when `4^num_qubits` overflows or `index` is outside the +/// basis. +pub fn basis_bitmask(num_qubits: usize, index: usize) -> Result { + let paulis = basis_element(num_qubits, index)?; + Ok(bitmask_from_paulis(&paulis)) +} + +/// Returns the Pauli-basis index for a bitmask in the canonical ordering. +/// +/// # Errors +/// +/// Returns [`ChannelError::QubitOutOfRange`] when the bitmask touches a qubit +/// outside `0..num_qubits`. +pub fn basis_index(num_qubits: usize, pauli: &PauliBitmaskSmall) -> Result { + pauli_basis_len(num_qubits)?; + validate_num_qubits(num_qubits, pauli)?; + let mut index = 0usize; + for qubit in 0..num_qubits { + let digit = match (pauli.has_x(qubit), pauli.has_z(qubit)) { + (false, false) => 0, + (true, false) => 1, + (true, true) => 2, + (false, true) => 3, + }; + index += digit << (2 * qubit); + } + Ok(index) +} + +/// Returns the canonical display label for a bitmask. +/// +/// # Errors +/// +/// Returns [`ChannelError::QubitOutOfRange`] when the bitmask touches a qubit +/// outside `0..num_qubits`. +pub fn bitmask_label(num_qubits: usize, pauli: &PauliBitmaskSmall) -> Result { + basis_label(num_qubits, basis_index(num_qubits, pauli)?) +} + +/// Converts a [`PauliString`] into the phase-free bitmask used by channel +/// representations. +/// +/// # Errors +/// +/// Returns [`ChannelError::QubitOutOfRange`] when the Pauli string touches a +/// qubit outside `0..num_qubits`. +pub fn pauli_string_to_bitmask( + num_qubits: usize, + pauli: &PauliString, +) -> Result { + let mut out = PauliBitmaskSmall::identity(); + for (p, q) in pauli.iter_pairs() { + let q = q.index(); + if q >= num_qubits { + return Err(ChannelError::QubitOutOfRange { + num_qubits, + qubit: q, + }); + } + match p { + Pauli::I => {} + Pauli::X => out.x_bits.set_bit(q), + Pauli::Y => { + out.x_bits.set_bit(q); + out.z_bits.set_bit(q); + } + Pauli::Z => out.z_bits.set_bit(q), + } + } + Ok(out) +} + +/// Sparse complex sum of Pauli operators. +#[derive(Clone, Debug, PartialEq)] +pub struct PauliSum { + num_qubits: usize, + terms: BTreeMap, +} + +impl PauliSum { + /// Constructs an empty Pauli sum over `num_qubits`. + #[must_use] + pub fn new(num_qubits: usize) -> Self { + Self { + num_qubits, + terms: BTreeMap::new(), + } + } + + /// Constructs a Pauli sum after validating term qubit ranges and + /// simplifying near-zero coefficients. + /// + /// # Errors + /// + /// Returns an error when any term touches a qubit outside `0..num_qubits` + /// or any coefficient is not finite. + pub fn try_new( + num_qubits: usize, + terms: BTreeMap, + ) -> Result { + Self::try_new_with_tolerance(num_qubits, terms, DEFAULT_TOLERANCE) + } + + /// Constructs a Pauli sum with an explicit zero-dropping tolerance. + /// + /// # Errors + /// + /// Returns an error when any term touches a qubit outside `0..num_qubits` + /// or any coefficient is not finite. + pub fn try_new_with_tolerance( + num_qubits: usize, + terms: BTreeMap, + tolerance: f64, + ) -> Result { + let mut out = Self::new(num_qubits); + for (pauli, coefficient) in terms { + out.add_term_with_tolerance(pauli, coefficient, tolerance)?; + } + Ok(out) + } + + /// Constructs a Pauli sum containing one [`PauliString`]. + /// + /// The `PauliString` phase becomes the complex coefficient. The stored + /// Pauli label itself is phase-free. + /// + /// # Errors + /// + /// Returns an error when `pauli` touches a qubit outside `0..num_qubits`. + pub fn from_pauli_string(num_qubits: usize, pauli: &PauliString) -> Result { + let label = pauli_string_to_bitmask(num_qubits, pauli)?; + let coefficient = pauli.phase().to_complex(); + let mut terms = BTreeMap::new(); + terms.insert(label, coefficient); + Self::try_new(num_qubits, terms) + } + + /// Returns the number of qubits represented by this sum. + #[must_use] + pub fn num_qubits(&self) -> usize { + self.num_qubits + } + + /// Returns the sparse Pauli terms and complex coefficients. + #[must_use] + pub fn terms(&self) -> &BTreeMap { + &self.terms + } + + /// Adds one term, merging with an existing coefficient if needed. + /// + /// # Errors + /// + /// Returns an error when `pauli` touches a qubit outside + /// `0..self.num_qubits` or `coefficient` is not finite. + pub fn add_term( + &mut self, + pauli: PauliBitmaskSmall, + coefficient: Complex64, + ) -> Result<(), ChannelError> { + self.add_term_with_tolerance(pauli, coefficient, DEFAULT_TOLERANCE) + } + + /// Adds one term with an explicit zero-dropping tolerance. + /// + /// # Errors + /// + /// Returns an error when `pauli` touches a qubit outside + /// `0..self.num_qubits` or `coefficient` is not finite. + pub fn add_term_with_tolerance( + &mut self, + pauli: PauliBitmaskSmall, + coefficient: Complex64, + tolerance: f64, + ) -> Result<(), ChannelError> { + validate_num_qubits(self.num_qubits, &pauli)?; + validate_complex(coefficient)?; + if coefficient.norm() <= tolerance { + return Ok(()); + } + + match self.terms.entry(pauli) { + std::collections::btree_map::Entry::Occupied(mut entry) => { + *entry.get_mut() += coefficient; + if entry.get().norm() <= tolerance { + entry.remove(); + } + } + std::collections::btree_map::Entry::Vacant(entry) => { + entry.insert(coefficient); + } + } + Ok(()) + } + + /// Drops near-zero coefficients in-place. + pub fn simplify_with_tolerance(&mut self, tolerance: f64) { + self.terms + .retain(|_, coefficient| coefficient.norm() > tolerance); + } + + /// Drops coefficients at the default tolerance and returns the simplified + /// sum. + #[must_use] + pub fn simplify(mut self) -> Self { + self.simplify_with_tolerance(DEFAULT_TOLERANCE); + self + } + + /// Returns the Pauli conjugation `P * self * P†`. + /// + /// Pauli conjugation preserves each Pauli label and flips the coefficient + /// sign for terms that anticommute with `P`. + /// + /// # Errors + /// + /// Returns an error when `pauli` touches a qubit outside this sum's qubit + /// range. + pub fn conjugated_by_pauli_string(&self, pauli: &PauliString) -> Result { + let label = pauli_string_to_bitmask(self.num_qubits, pauli)?; + let mut terms = BTreeMap::new(); + for (term, coefficient) in &self.terms { + let sign = if label.commutes_with(term) { 1.0 } else { -1.0 }; + terms.insert(term.clone(), *coefficient * sign); + } + Ok(Self { + num_qubits: self.num_qubits, + terms, + }) + } + + /// Returns the trace of the represented operator. + /// + /// The trace is `identity_coefficient * 2^num_qubits`. + #[allow(clippy::cast_precision_loss)] + #[must_use] + pub fn trace(&self) -> Complex64 { + let dim = 2usize + .checked_pow(self.num_qubits.try_into().unwrap_or(u32::MAX)) + .unwrap_or(usize::MAX); + self.terms + .get(&PauliBitmaskSmall::identity()) + .copied() + .unwrap_or_else(|| Complex64::new(0.0, 0.0)) + * dim as f64 + } +} + +impl fmt::Display for PauliSum { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + if self.terms.is_empty() { + return write!(f, "0"); + } + for (idx, (pauli, coefficient)) in self.terms.iter().enumerate() { + if idx > 0 { + write!(f, " + ")?; + } + let label = bitmask_label(self.num_qubits, pauli).map_err(|_| fmt::Error)?; + write!(f, "({coefficient}){label}")?; + } + Ok(()) + } +} + +impl Add for PauliSum { + type Output = Self; + + fn add(mut self, rhs: Self) -> Self::Output { + assert_eq!( + self.num_qubits, rhs.num_qubits, + "cannot add PauliSum values with different qubit counts" + ); + for (pauli, coefficient) in rhs.terms { + self.add_term(pauli, coefficient) + .expect("validated RHS term must remain valid"); + } + self + } +} + +impl Mul for PauliSum { + type Output = Self; + + fn mul(mut self, rhs: Complex64) -> Self::Output { + for coefficient in self.terms.values_mut() { + *coefficient *= rhs; + } + self.simplify() + } +} + +impl Mul for Complex64 { + type Output = PauliSum; + + fn mul(self, rhs: PauliSum) -> Self::Output { + rhs * self + } +} + +impl Mul for PauliSum { + type Output = Self; + + fn mul(self, rhs: f64) -> Self::Output { + self * Complex64::new(rhs, 0.0) + } +} + +impl Mul for f64 { + type Output = PauliSum; + + fn mul(self, rhs: PauliSum) -> Self::Output { + rhs * self + } +} + +impl Mul for PauliString { + type Output = PauliSum; + + fn mul(self, rhs: PauliSum) -> Self::Output { + rhs.conjugated_by_pauli_string(&self) + .expect("PauliString touches outside PauliSum qubit range") + } +} + +impl Mul<&PauliSum> for &PauliString { + type Output = PauliSum; + + fn mul(self, rhs: &PauliSum) -> Self::Output { + rhs.conjugated_by_pauli_string(self) + .expect("PauliString touches outside PauliSum qubit range") + } +} + +/// Sparse Pauli error channel represented by probabilities. +#[derive(Clone, Debug, PartialEq)] +pub struct PauliChannel { + num_qubits: usize, + basis_order: PtmBasisOrder, + probabilities: BTreeMap, +} + +impl PauliChannel { + /// Constructs a Pauli channel after validating probabilities. + /// + /// Missing Pauli terms are treated as zero probability. Stored + /// probabilities must be finite, non-negative, and sum to one. + /// + /// # Errors + /// + /// Returns an error when a term is outside the declared qubit range, a + /// probability is non-finite or negative, or probabilities do not sum to + /// one. + pub fn try_new( + num_qubits: usize, + probabilities: BTreeMap, + ) -> Result { + Self::try_new_with_tolerance(num_qubits, probabilities, DEFAULT_TOLERANCE) + } + + /// Constructs a Pauli channel with an explicit tolerance. + /// + /// # Errors + /// + /// Returns an error when a term is outside the declared qubit range, a + /// probability is non-finite or negative, or probabilities do not sum to + /// one within `tolerance`. + pub fn try_new_with_tolerance( + num_qubits: usize, + probabilities: BTreeMap, + tolerance: f64, + ) -> Result { + let mut cleaned = BTreeMap::new(); + let mut sum = 0.0; + for (pauli, probability) in probabilities { + validate_num_qubits(num_qubits, &pauli)?; + validate_probability(probability, tolerance)?; + let probability = if probability.abs() <= tolerance { + 0.0 + } else { + probability + }; + if probability > 0.0 { + cleaned.insert(pauli, probability); + } + sum += probability; + } + if (sum - 1.0).abs() > tolerance { + return Err(ChannelError::ProbabilitySum { sum, tolerance }); + } + Ok(Self { + num_qubits, + basis_order: PtmBasisOrder::default(), + probabilities: cleaned, + }) + } + + /// Constructs a one-qubit Pauli channel from non-identity probabilities. + /// + /// # Errors + /// + /// Returns an error when probabilities are invalid or do not leave a valid + /// identity probability. + pub fn one_qubit(px: f64, py: f64, pz: f64) -> Result { + let mut probabilities = BTreeMap::new(); + probabilities.insert(PauliBitmaskSmall::identity(), 1.0 - px - py - pz); + probabilities.insert(PauliBitmaskSmall::x(0), px); + probabilities.insert(PauliBitmaskSmall::y(0), py); + probabilities.insert(PauliBitmaskSmall::z(0), pz); + Self::try_new(1, probabilities) + } + + /// Converts a real, non-negative [`PauliSum`] into a Pauli channel. + /// + /// # Errors + /// + /// Returns an error when any coefficient has a non-negligible imaginary + /// part, is negative, or the real coefficients do not sum to one. + pub fn from_pauli_sum(sum: &PauliSum) -> Result { + let mut probabilities = BTreeMap::new(); + for (pauli, coefficient) in sum.terms() { + if coefficient.im.abs() > DEFAULT_TOLERANCE { + return Err(ChannelError::NonRealCoefficient { + value: *coefficient, + tolerance: DEFAULT_TOLERANCE, + }); + } + probabilities.insert(pauli.clone(), coefficient.re); + } + Self::try_new(sum.num_qubits(), probabilities) + } + + /// Converts a symbolic channel expression into a Pauli channel when it is + /// a mixture of Pauli unitaries. + /// + /// This accepts the common constructors for bit-flip, dephasing, + /// depolarizing, and general mixed-Pauli channels. Non-Pauli unitary + /// mixtures are intentionally rejected instead of silently projecting them. + /// + /// # Errors + /// + /// Returns an error when `channel` is not a supported Pauli-unitary + /// mixture or when its probabilities are invalid. + pub fn from_channel_expr(channel: &ChannelExpr) -> Result { + let num_qubits = channel_num_qubits(channel).max(1); + match channel { + ChannelExpr::Unitary(unitary) => { + let pauli = unitary_rep_to_pauli_bitmask(num_qubits, unitary)?; + let mut probabilities = BTreeMap::new(); + probabilities.insert(pauli, 1.0); + Self::try_new(num_qubits, probabilities) + } + ChannelExpr::MixedUnitary(ops) => { + let mut probabilities = BTreeMap::new(); + for (probability, unitary) in ops { + validate_probability(*probability, DEFAULT_TOLERANCE)?; + let pauli = unitary_rep_to_pauli_bitmask(num_qubits, unitary)?; + *probabilities.entry(pauli).or_insert(0.0) += *probability; + } + Self::try_new(num_qubits, probabilities) + } + _ => Err(ChannelError::UnsupportedChannelExpr { + reason: "only Pauli-unitary channels can be converted to PauliChannel".to_string(), + }), + } + } + + /// Converts Pauli probabilities to diagonal PTM entries. + /// + /// # Errors + /// + /// Returns an error if the Pauli-basis dimension overflows. + pub fn to_diagonal_ptm(&self) -> Result { + let basis_len = pauli_basis_len(self.num_qubits)?; + let mut fidelities = BTreeMap::new(); + for basis_index in 0..basis_len { + let basis = basis_bitmask(self.num_qubits, basis_index)?; + let fidelity = self + .probabilities + .iter() + .map(|(error, probability)| probability * commutation_character(error, &basis)) + .sum(); + fidelities.insert(basis, fidelity); + } + DiagonalPtm::try_new(self.num_qubits, fidelities) + } + + /// Converts this Pauli channel to a dense PTM. + /// + /// # Errors + /// + /// Returns an error if the Pauli-basis dimension overflows. + pub fn to_ptm(&self) -> Result { + self.to_diagonal_ptm()?.to_ptm() + } + + /// Returns the number of qubits represented by this channel. + #[must_use] + pub fn num_qubits(&self) -> usize { + self.num_qubits + } + + /// Returns the PTM basis ordering. + #[must_use] + pub fn basis_order(&self) -> PtmBasisOrder { + self.basis_order + } + + /// Returns the sparse probability map. + #[must_use] + pub fn probabilities(&self) -> &BTreeMap { + &self.probabilities + } + + /// Returns the probability of a specific Pauli error. + #[must_use] + pub fn probability(&self, pauli: &PauliBitmaskSmall) -> f64 { + self.probabilities.get(pauli).copied().unwrap_or(0.0) + } + + /// Returns the total non-identity probability. + #[must_use] + pub fn total_error_rate(&self) -> f64 { + self.probabilities + .iter() + .filter(|(pauli, _)| !pauli.is_identity()) + .map(|(_, probability)| probability) + .sum() + } +} + +/// Sparse diagonal Pauli transfer matrix. +#[derive(Clone, Debug, PartialEq)] +pub struct DiagonalPtm { + num_qubits: usize, + basis_order: PtmBasisOrder, + fidelities: BTreeMap, +} + +impl DiagonalPtm { + /// Constructs a diagonal PTM after validating term qubit ranges. + /// + /// Missing Pauli terms are treated as zero fidelity. + /// + /// # Errors + /// + /// Returns an error when any term is outside the declared qubit range or + /// any fidelity is non-finite. + pub fn try_new( + num_qubits: usize, + fidelities: BTreeMap, + ) -> Result { + let mut cleaned = BTreeMap::new(); + for (pauli, fidelity) in fidelities { + validate_num_qubits(num_qubits, &pauli)?; + validate_real(fidelity)?; + if fidelity.abs() > DEFAULT_TOLERANCE { + cleaned.insert(pauli, fidelity); + } + } + Ok(Self { + num_qubits, + basis_order: PtmBasisOrder::default(), + fidelities: cleaned, + }) + } + + /// Converts diagonal PTM entries to Pauli-channel probabilities. + /// + /// # Errors + /// + /// Returns an error if the Pauli-basis dimension overflows or the inverse + /// Walsh-Hadamard transform does not produce valid probabilities. + pub fn to_pauli_channel(&self) -> Result { + let basis_len = pauli_basis_len(self.num_qubits)?; + #[allow(clippy::cast_precision_loss)] + let scale = basis_len as f64; + let basis: Vec = (0..basis_len) + .map(|basis_index| basis_bitmask(self.num_qubits, basis_index)) + .collect::>()?; + let mut probabilities = BTreeMap::new(); + for error in &basis { + let probability: f64 = basis + .iter() + .map(|basis_element| { + self.fidelity(basis_element) * commutation_character(error, basis_element) + }) + .sum::() + / scale; + probabilities.insert(error.clone(), probability); + } + PauliChannel::try_new(self.num_qubits, probabilities) + } + + /// Converts a symbolic Pauli-unitary channel expression to diagonal PTM + /// entries. + /// + /// # Errors + /// + /// Returns an error when the expression is not a supported Pauli-unitary + /// mixture or when probabilities are invalid. + pub fn from_channel_expr(channel: &ChannelExpr) -> Result { + PauliChannel::from_channel_expr(channel)?.to_diagonal_ptm() + } + + /// Expands this diagonal PTM into a dense PTM matrix. + /// + /// # Errors + /// + /// Returns an error if the Pauli-basis dimension overflows. + pub fn to_ptm(&self) -> Result { + let basis_len = pauli_basis_len(self.num_qubits)?; + let mut matrix = DMatrix::zeros(basis_len, basis_len); + for basis_idx in 0..basis_len { + let basis = basis_bitmask(self.num_qubits, basis_idx)?; + matrix[(basis_idx, basis_idx)] = self.fidelity(&basis); + } + Ptm::try_new(self.num_qubits, matrix) + } + + /// Returns the number of qubits represented by this diagonal PTM. + #[must_use] + pub fn num_qubits(&self) -> usize { + self.num_qubits + } + + /// Returns the PTM basis ordering. + #[must_use] + pub fn basis_order(&self) -> PtmBasisOrder { + self.basis_order + } + + /// Returns the sparse fidelity map. + #[must_use] + pub fn fidelities(&self) -> &BTreeMap { + &self.fidelities + } + + /// Returns the fidelity for a specific Pauli basis element. + #[must_use] + pub fn fidelity(&self, pauli: &PauliBitmaskSmall) -> f64 { + self.fidelities.get(pauli).copied().unwrap_or(0.0) + } +} + +/// Dense Pauli transfer matrix in the canonical PECOS Pauli basis. +/// +/// PTM entries use the normalized convention +/// `R_ij = (1/d) Tr[P_i E(P_j)]`, where `d = 2^num_qubits`. +/// Rows index output Paulis, columns index input Paulis. +#[derive(Clone, Debug, PartialEq)] +pub struct Ptm { + num_qubits: usize, + basis_order: PtmBasisOrder, + matrix: DMatrix, +} + +impl Ptm { + /// Constructs a dense PTM after validating the structural shape. + /// + /// # Errors + /// + /// Returns an error when `matrix` is not `4^num_qubits x 4^num_qubits` + /// or contains non-finite entries. + pub fn try_new(num_qubits: usize, matrix: DMatrix) -> Result { + let basis_len = pauli_basis_len(num_qubits)?; + if matrix.nrows() != basis_len || matrix.ncols() != basis_len { + return Err(ChannelError::InvalidMatrixShape { + expected_rows: basis_len, + expected_cols: basis_len, + rows: matrix.nrows(), + cols: matrix.ncols(), + }); + } + for value in matrix.iter() { + validate_real(*value)?; + } + Ok(Self { + num_qubits, + basis_order: PtmBasisOrder::default(), + matrix, + }) + } + + /// Constructs the identity channel PTM over `num_qubits`. + /// + /// # Errors + /// + /// Returns an error if the Pauli-basis dimension overflows. + pub fn identity(num_qubits: usize) -> Result { + let basis_len = pauli_basis_len(num_qubits)?; + Self::try_new(num_qubits, DMatrix::identity(basis_len, basis_len)) + } + + /// Constructs a dense PTM from a diagonal PTM. + /// + /// # Errors + /// + /// Returns an error if the Pauli-basis dimension overflows. + pub fn from_diagonal_ptm(diagonal: &DiagonalPtm) -> Result { + diagonal.to_ptm() + } + + /// Constructs a dense PTM from a Pauli channel. + /// + /// # Errors + /// + /// Returns an error if the Pauli-basis dimension overflows. + pub fn from_pauli_channel(channel: &PauliChannel) -> Result { + channel.to_ptm() + } + + /// Constructs the PTM for a unitary conjugation channel. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow or numerical entries have + /// significant imaginary components. + pub fn from_unitary(unitary: &UnitaryRep, num_qubits: usize) -> Result { + let basis_len = pauli_basis_len(num_qubits)?; + let dim = hilbert_dim(num_qubits)?; + #[allow(clippy::cast_precision_loss)] + let dim_f = dim as f64; + let unitary_matrix = to_matrix_with_size(unitary, num_qubits).into_inner(); + if unitary_matrix.nrows() != dim || unitary_matrix.ncols() != dim { + return Err(ChannelError::InvalidMatrixShape { + expected_rows: dim, + expected_cols: dim, + rows: unitary_matrix.nrows(), + cols: unitary_matrix.ncols(), + }); + } + let unitary_adjoint = unitary_matrix.adjoint(); + let basis_matrices = pauli_basis_matrices(num_qubits)?; + let mut matrix = DMatrix::zeros(basis_len, basis_len); + for input_idx in 0..basis_len { + let evolved = &unitary_matrix * &basis_matrices[input_idx] * &unitary_adjoint; + for output_idx in 0..basis_len { + let entry = trace_complex(&(&basis_matrices[output_idx] * &evolved)) / dim_f; + if entry.im.abs() > DEFAULT_TOLERANCE { + return Err(ChannelError::NonRealCoefficient { + value: entry, + tolerance: DEFAULT_TOLERANCE, + }); + } + matrix[(output_idx, input_idx)] = entry.re; + } + } + Self::try_new(num_qubits, matrix) + } + + /// Converts a symbolic channel expression to a dense PTM when supported. + /// + /// This supports unitary, mixed-unitary, amplitude-damping, phase-damping, + /// tensor, and composed channel expressions that can be represented by + /// [`KrausOps`]. Erasure/leakage channels are intentionally rejected until + /// PECOS has an explicit flag or extended-Hilbert-space representation. + /// + /// # Errors + /// + /// Returns an error when the expression is unsupported or structurally + /// invalid. + pub fn from_channel_expr(channel: &ChannelExpr) -> Result { + let num_qubits = channel_num_qubits(channel).max(1); + match channel { + ChannelExpr::Unitary(unitary) => Self::from_unitary(unitary, num_qubits), + ChannelExpr::MixedUnitary(ops) => { + let basis_len = pauli_basis_len(num_qubits)?; + let mut matrix = DMatrix::zeros(basis_len, basis_len); + let mut total_probability = 0.0; + for (probability, unitary) in ops { + validate_probability(*probability, DEFAULT_TOLERANCE)?; + let unitary_ptm = Self::from_unitary(unitary, num_qubits)?; + matrix += unitary_ptm.matrix * *probability; + total_probability += *probability; + } + if (total_probability - 1.0).abs() > DEFAULT_TOLERANCE { + return Err(ChannelError::ProbabilitySum { + sum: total_probability, + tolerance: DEFAULT_TOLERANCE, + }); + } + Self::try_new(num_qubits, matrix) + } + ChannelExpr::AmplitudeDamping { .. } + | ChannelExpr::PhaseDamping { .. } + | ChannelExpr::Tensor(_) + | ChannelExpr::Compose(_) => KrausOps::from_channel_expr(channel)?.to_ptm(), + _ => Err(ChannelError::UnsupportedChannelExpr { + reason: "dense PTM conversion supports unitary, mixed-unitary, amplitude-damping, phase-damping, tensor, and compose channels".to_string(), + }), + } + } + + /// Returns the number of qubits represented by this PTM. + #[must_use] + pub fn num_qubits(&self) -> usize { + self.num_qubits + } + + /// Returns the PTM basis ordering. + #[must_use] + pub fn basis_order(&self) -> PtmBasisOrder { + self.basis_order + } + + /// Returns the dense PTM matrix. + #[must_use] + pub fn matrix(&self) -> &DMatrix { + &self.matrix + } + + /// Consumes this PTM and returns its dense matrix. + #[must_use] + pub fn into_matrix(self) -> DMatrix { + self.matrix + } + + /// Returns one PTM entry by row/output and column/input basis indices. + #[must_use] + pub fn entry(&self, output: usize, input: usize) -> f64 { + self.matrix[(output, input)] + } + + /// Converts this PTM to a Choi matrix. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow or the conversion encounters + /// invalid matrix data. + pub fn to_choi(&self) -> Result { + ChoiMatrix::from_ptm(self) + } + + /// Converts this PTM to Kraus operators through its Choi representation. + /// + /// # Errors + /// + /// Returns an error when the Choi conversion or numerical decomposition + /// fails. + pub fn to_kraus(&self) -> Result { + self.to_choi()?.to_kraus() + } +} + +/// Concrete Kraus-operator representation of a quantum channel. +/// +/// A Kraus channel applies +/// `E(rho) = sum_k K_k rho K_k†`. +/// Operators are full `2^n x 2^n` matrices using the same little-endian +/// computational-basis convention as [`UnitaryMatrix`](crate::UnitaryMatrix). +#[derive(Clone, Debug, PartialEq)] +pub struct KrausOps { + num_qubits: usize, + operators: Vec>, +} + +impl KrausOps { + /// Constructs a Kraus representation after structural validation. + /// + /// This validates only cheap structural properties: non-empty operator + /// list, matrix shape, and finite entries. Trace-preservation and complete + /// positivity are mathematical properties of the Kraus form; call + /// [`Self::is_trace_preserving_with_tolerance`] when that check is needed. + /// + /// # Errors + /// + /// Returns an error when the operator list is empty, a matrix has the + /// wrong shape, a dimension overflows, or an entry is not finite. + pub fn try_new( + num_qubits: usize, + operators: Vec>, + ) -> Result { + if operators.is_empty() { + return Err(ChannelError::EmptyKrausSet); + } + let dim = hilbert_dim(num_qubits)?; + for operator in &operators { + validate_complex_matrix(operator, dim, dim)?; + } + Ok(Self { + num_qubits, + operators, + }) + } + + /// Constructs a one-operator Kraus representation for a unitary channel. + /// + /// # Errors + /// + /// Returns an error when the embedded unitary matrix has an invalid shape. + pub fn from_unitary(unitary: &UnitaryRep, num_qubits: usize) -> Result { + let operator = to_matrix_with_size(unitary, num_qubits).into_inner(); + Self::try_new(num_qubits, vec![operator]) + } + + /// Converts a symbolic channel expression to Kraus operators when + /// supported. + /// + /// Supported variants are unitary, mixed-unitary, amplitude damping, phase + /// damping, tensor, and compose. Measurement/preparation gate expressions, + /// erasure, and leakage are intentionally rejected because they need + /// instrument or flag semantics beyond a simple same-Hilbert-space Kraus + /// channel. + /// + /// # Errors + /// + /// Returns an error when the expression is unsupported or invalid. + pub fn from_channel_expr(channel: &ChannelExpr) -> Result { + let num_qubits = channel_num_qubits(channel).max(1); + kraus_from_channel_expr_with_size(channel, num_qubits) + } + + /// Converts this Kraus channel to a dense PTM. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow or a PTM entry has a + /// significant imaginary component. + pub fn to_ptm(&self) -> Result { + let basis_len = pauli_basis_len(self.num_qubits)?; + let dim = hilbert_dim(self.num_qubits)?; + #[allow(clippy::cast_precision_loss)] + let dim_f = dim as f64; + let basis_matrices = pauli_basis_matrices(self.num_qubits)?; + let mut matrix = DMatrix::zeros(basis_len, basis_len); + for input_idx in 0..basis_len { + let mut evolved = DMatrix::zeros(dim, dim); + for operator in &self.operators { + evolved += operator * &basis_matrices[input_idx] * operator.adjoint(); + } + for output_idx in 0..basis_len { + let entry = trace_complex(&(&basis_matrices[output_idx] * &evolved)) / dim_f; + if entry.im.abs() > DEFAULT_TOLERANCE { + return Err(ChannelError::NonRealCoefficient { + value: entry, + tolerance: DEFAULT_TOLERANCE, + }); + } + matrix[(output_idx, input_idx)] = entry.re; + } + } + Ptm::try_new(self.num_qubits, matrix) + } + + /// Converts this Kraus channel to a Choi matrix. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn to_choi(&self) -> Result { + ChoiMatrix::from_kraus(self) + } + + /// Returns whether `sum_k K_k† K_k = I` within the default tolerance. + #[must_use] + pub fn is_trace_preserving(&self) -> bool { + self.is_trace_preserving_with_tolerance(1e-10) + } + + /// Returns whether `sum_k K_k† K_k = I` within `tolerance`. + #[must_use] + pub fn is_trace_preserving_with_tolerance(&self, tolerance: f64) -> bool { + let Ok(dim) = hilbert_dim(self.num_qubits) else { + return false; + }; + let mut accumulator = DMatrix::zeros(dim, dim); + for operator in &self.operators { + accumulator += operator.adjoint() * operator; + } + let identity = DMatrix::::identity(dim, dim); + matrix_max_abs_diff(&accumulator, &identity) <= tolerance + } + + /// Returns the number of qubits represented by this channel. + #[must_use] + pub fn num_qubits(&self) -> usize { + self.num_qubits + } + + /// Returns the Kraus operators. + #[must_use] + pub fn operators(&self) -> &[DMatrix] { + &self.operators + } + + /// Consumes this value and returns the Kraus operators. + #[must_use] + pub fn into_operators(self) -> Vec> { + self.operators + } +} + +/// Concrete Choi representation of a quantum channel. +/// +/// PECOS stores the unnormalized Choi matrix +/// `J = sum_k vec(K_k) vec(K_k)†`, where `vec` is column-stacking. For a +/// trace-preserving channel on Hilbert dimension `d`, `Tr(J) = d` and +/// `Tr_output(J) = I_input`. +#[derive(Clone, Debug, PartialEq)] +pub struct ChoiMatrix { + num_qubits: usize, + matrix: DMatrix, +} + +impl ChoiMatrix { + /// Constructs a Choi matrix after structural validation. + /// + /// This validates only cheap structural properties: shape and finite + /// entries. Complete positivity and trace preservation are explicit + /// follow-up checks. + /// + /// # Errors + /// + /// Returns an error when the matrix shape is not `4^n x 4^n`, dimensions + /// overflow, or an entry is not finite. + pub fn try_new(num_qubits: usize, matrix: DMatrix) -> Result { + let dim_squared = pauli_basis_len(num_qubits)?; + validate_complex_matrix(&matrix, dim_squared, dim_squared)?; + Ok(Self { num_qubits, matrix }) + } + + /// Converts Kraus operators to a Choi matrix. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn from_kraus(kraus: &KrausOps) -> Result { + let dim = hilbert_dim(kraus.num_qubits)?; + let dim_squared = pauli_basis_len(kraus.num_qubits)?; + let mut matrix = DMatrix::zeros(dim_squared, dim_squared); + for operator in kraus.operators() { + for input_col in 0..dim { + for output_row in 0..dim { + let row = choi_index(dim, output_row, input_col); + let row_value = operator[(output_row, input_col)]; + for input_col_2 in 0..dim { + for output_row_2 in 0..dim { + let col = choi_index(dim, output_row_2, input_col_2); + matrix[(row, col)] += + row_value * operator[(output_row_2, input_col_2)].conj(); + } + } + } + } + } + Self::try_new(kraus.num_qubits, matrix) + } + + /// Constructs a Choi matrix for a unitary channel. + /// + /// # Errors + /// + /// Returns an error when unitary embedding or Choi construction fails. + pub fn from_unitary(unitary: &UnitaryRep, num_qubits: usize) -> Result { + KrausOps::from_unitary(unitary, num_qubits)?.to_choi() + } + + /// Converts a symbolic channel expression to a Choi matrix when supported. + /// + /// # Errors + /// + /// Returns an error when [`KrausOps::from_channel_expr`] rejects the + /// expression or Choi construction fails. + pub fn from_channel_expr(channel: &ChannelExpr) -> Result { + KrausOps::from_channel_expr(channel)?.to_choi() + } + + /// Converts a PTM to a Choi matrix. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn from_ptm(ptm: &Ptm) -> Result { + let dim = hilbert_dim(ptm.num_qubits)?; + let dim_squared = pauli_basis_len(ptm.num_qubits)?; + let mut matrix = DMatrix::zeros(dim_squared, dim_squared); + for input_row in 0..dim { + for input_col in 0..dim { + let mut matrix_unit = DMatrix::zeros(dim, dim); + matrix_unit[(input_row, input_col)] = Complex64::new(1.0, 0.0); + let evolved = apply_ptm_to_operator(ptm, &matrix_unit)?; + for output_row in 0..dim { + for output_col in 0..dim { + matrix[( + choi_index(dim, output_row, input_row), + choi_index(dim, output_col, input_col), + )] = evolved[(output_row, output_col)]; + } + } + } + } + Self::try_new(ptm.num_qubits, matrix) + } + + /// Converts this Choi matrix to a dense PTM. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow or a PTM entry has a + /// significant imaginary component. + pub fn to_ptm(&self) -> Result { + let basis_len = pauli_basis_len(self.num_qubits)?; + let dim = hilbert_dim(self.num_qubits)?; + #[allow(clippy::cast_precision_loss)] + let dim_f = dim as f64; + let basis_matrices = pauli_basis_matrices(self.num_qubits)?; + let mut matrix = DMatrix::zeros(basis_len, basis_len); + for input_idx in 0..basis_len { + let evolved = self.apply_to_operator(&basis_matrices[input_idx])?; + for output_idx in 0..basis_len { + let entry = trace_complex(&(&basis_matrices[output_idx] * &evolved)) / dim_f; + if entry.im.abs() > DEFAULT_TOLERANCE { + return Err(ChannelError::NonRealCoefficient { + value: entry, + tolerance: DEFAULT_TOLERANCE, + }); + } + matrix[(output_idx, input_idx)] = entry.re; + } + } + Ptm::try_new(self.num_qubits, matrix) + } + + /// Converts this Choi matrix to a Kraus representation using SVD. + /// + /// For a valid positive-semidefinite Choi matrix, the singular values are + /// the Choi eigenvalues and the left singular vectors produce a Kraus + /// decomposition. This method reconstructs the Choi matrix from the + /// resulting Kraus operators and rejects inputs that are not positive + /// semidefinite within the requested tolerance. + /// + /// # Errors + /// + /// Returns an error when numerical decomposition fails. + pub fn to_kraus(&self) -> Result { + self.to_kraus_with_tolerance(DEFAULT_TOLERANCE) + } + + /// Converts this Choi matrix to Kraus operators with an explicit + /// singular-value cutoff. + /// + /// # Errors + /// + /// Returns an error when the tolerance is invalid, numerical decomposition + /// fails, or the input is not positive semidefinite within tolerance. + pub fn to_kraus_with_tolerance(&self, tolerance: f64) -> Result { + if !tolerance.is_finite() || tolerance < 0.0 { + return Err(ChannelError::DecompositionFailed { + reason: format!("invalid Kraus decomposition tolerance: {tolerance}"), + }); + } + let dim = hilbert_dim(self.num_qubits)?; + let svd = SVD::new(self.matrix.clone(), true, false); + let u = svd.u.ok_or_else(|| ChannelError::DecompositionFailed { + reason: "SVD did not return left singular vectors".to_string(), + })?; + let mut operators = Vec::new(); + for (idx, singular_value) in svd.singular_values.iter().copied().enumerate() { + if singular_value <= tolerance { + continue; + } + let scale = Complex64::new(singular_value.sqrt(), 0.0); + let mut operator = DMatrix::zeros(dim, dim); + for input_col in 0..dim { + for output_row in 0..dim { + operator[(output_row, input_col)] = + u[(choi_index(dim, output_row, input_col), idx)] * scale; + } + } + operators.push(operator); + } + if operators.is_empty() { + operators.push(DMatrix::zeros(dim, dim)); + } + let kraus = KrausOps::try_new(self.num_qubits, operators)?; + let recovered = Self::from_kraus(&kraus)?; + let reconstruction_tolerance = (10.0 * tolerance).max(1e-10); + if matrix_max_abs_diff(recovered.matrix(), &self.matrix) > reconstruction_tolerance { + return Err(ChannelError::DecompositionFailed { + reason: "Choi matrix is not positive semidefinite within tolerance".to_string(), + }); + } + Ok(kraus) + } + + /// Applies the represented channel to an operator matrix. + /// + /// # Errors + /// + /// Returns an error when the input operator shape is invalid. + pub fn apply_to_operator( + &self, + operator: &DMatrix, + ) -> Result, ChannelError> { + let dim = hilbert_dim(self.num_qubits)?; + validate_complex_matrix(operator, dim, dim)?; + let mut out = DMatrix::zeros(dim, dim); + for input_row in 0..dim { + for input_col in 0..dim { + let coefficient = operator[(input_row, input_col)]; + for output_row in 0..dim { + for output_col in 0..dim { + out[(output_row, output_col)] += coefficient + * self.matrix[( + choi_index(dim, output_row, input_row), + choi_index(dim, output_col, input_col), + )]; + } + } + } + } + Ok(out) + } + + /// Returns whether `Tr_output(J) = I_input` within the default tolerance. + #[must_use] + pub fn is_trace_preserving(&self) -> bool { + self.is_trace_preserving_with_tolerance(1e-10) + } + + /// Returns whether `Tr_output(J) = I_input` within `tolerance`. + #[must_use] + pub fn is_trace_preserving_with_tolerance(&self, tolerance: f64) -> bool { + let Ok(dim) = hilbert_dim(self.num_qubits) else { + return false; + }; + let mut reduced = DMatrix::zeros(dim, dim); + for input_row in 0..dim { + for input_col in 0..dim { + let mut value = Complex64::new(0.0, 0.0); + for output in 0..dim { + value += self.matrix[( + choi_index(dim, output, input_row), + choi_index(dim, output, input_col), + )]; + } + reduced[(input_row, input_col)] = value; + } + } + let identity = DMatrix::::identity(dim, dim); + matrix_max_abs_diff(&reduced, &identity) <= tolerance + } + + /// Returns the number of qubits represented by this Choi matrix. + #[must_use] + pub fn num_qubits(&self) -> usize { + self.num_qubits + } + + /// Returns the dense Choi matrix. + #[must_use] + pub fn matrix(&self) -> &DMatrix { + &self.matrix + } + + /// Consumes this value and returns the dense Choi matrix. + #[must_use] + pub fn into_matrix(self) -> DMatrix { + self.matrix + } +} + +/// Returns the partial trace of a density matrix over selected qubits. +/// +/// Qubit indexing is little-endian: qubit 0 is the least-significant bit of +/// the computational-basis index. The returned density matrix keeps the +/// untraced qubits in ascending qubit-index order. +/// +/// # Errors +/// +/// Returns an error when the matrix is not `2^num_qubits x 2^num_qubits`, a +/// traced qubit is outside range, or a traced qubit is repeated. +pub fn partial_trace( + matrix: &DMatrix, + num_qubits: usize, + traced_qubits: &[usize], +) -> Result, ChannelError> { + let dim = hilbert_dim(num_qubits)?; + if matrix.nrows() != dim || matrix.ncols() != dim { + return Err(ChannelError::InvalidMatrixShape { + expected_rows: dim, + expected_cols: dim, + rows: matrix.nrows(), + cols: matrix.ncols(), + }); + } + + let mut traced = traced_qubits.to_vec(); + traced.sort_unstable(); + for window in traced.windows(2) { + if window[0] == window[1] { + return Err(ChannelError::DuplicateSubsystem { qubit: window[0] }); + } + } + for &qubit in &traced { + if qubit >= num_qubits { + return Err(ChannelError::QubitOutOfRange { num_qubits, qubit }); + } + } + + let kept: Vec = (0..num_qubits) + .filter(|qubit| traced.binary_search(qubit).is_err()) + .collect(); + let out_dim = 1usize << kept.len(); + let traced_dim = 1usize << traced.len(); + let mut out = DMatrix::zeros(out_dim, out_dim); + for kept_row in 0..out_dim { + for kept_col in 0..out_dim { + let mut value = Complex64::new(0.0, 0.0); + for traced_idx in 0..traced_dim { + let row = embed_subsystem_index(&kept, kept_row, &traced, traced_idx); + let col = embed_subsystem_index(&kept, kept_col, &traced, traced_idx); + value += matrix[(row, col)]; + } + out[(kept_row, kept_col)] = value; + } + } + Ok(out) +} + +/// Samples a random `num_qubits`-qubit Pauli string. +/// +/// Each qubit independently receives one of `I, X, Y, Z` with equal +/// probability. The all-identity Pauli is allowed. +pub fn random_pauli(rng: &mut R, num_qubits: usize) -> PauliString { + let paulis: Vec = (0..num_qubits) + .map(|_| match rng.random_range(0..4) { + 0 => Pauli::I, + 1 => Pauli::X, + 2 => Pauli::Y, + _ => Pauli::Z, + }) + .collect(); + PauliString::from_paulis(&paulis) +} + +/// Samples one of the 24 single-qubit Clifford gate primitives uniformly. +pub fn random_1q_clifford(rng: &mut R) -> Clifford { + let all = Clifford::all_1q(); + all[rng.random_range(0..all.len())] +} + +/// Samples one of the standard two-qubit Clifford gate primitives uniformly. +pub fn random_2q_clifford(rng: &mut R) -> Clifford { + let all = Clifford::all_2q(); + all[rng.random_range(0..all.len())] +} + +/// Samples one named Clifford gate primitive uniformly from the PECOS Clifford +/// enum. +pub fn random_clifford(rng: &mut R) -> Clifford { + let all = Clifford::all(); + all[rng.random_range(0..all.len())] +} + +fn bitmask_from_paulis(paulis: &[Pauli]) -> PauliBitmaskSmall { + let mut out = PauliBitmaskSmall::identity(); + for (qubit, pauli) in paulis.iter().copied().enumerate() { + match pauli { + Pauli::I => {} + Pauli::X => out.x_bits.set_bit(qubit), + Pauli::Y => { + out.x_bits.set_bit(qubit); + out.z_bits.set_bit(qubit); + } + Pauli::Z => out.z_bits.set_bit(qubit), + } + } + out +} + +fn channel_num_qubits(channel: &ChannelExpr) -> usize { + channel.qubits().into_iter().max().map_or(0, |q| q + 1) +} + +fn bitmask_to_pauli_string(num_qubits: usize, pauli: &PauliBitmaskSmall) -> PauliString { + let paulis: Vec = (0..num_qubits) + .map(|qubit| match (pauli.has_x(qubit), pauli.has_z(qubit)) { + (false, false) => Pauli::I, + (true, false) => Pauli::X, + (true, true) => Pauli::Y, + (false, true) => Pauli::Z, + }) + .collect(); + PauliString::from_paulis(&paulis) +} + +fn pauli_basis_matrices(num_qubits: usize) -> Result>, ChannelError> { + let basis_len = pauli_basis_len(num_qubits)?; + let mut out = Vec::with_capacity(basis_len); + for basis_idx in 0..basis_len { + let bitmask = basis_bitmask(num_qubits, basis_idx)?; + let pauli = bitmask_to_pauli_string(num_qubits, &bitmask); + out.push(to_matrix_with_size(&UnitaryRep::Pauli(pauli), num_qubits).into_inner()); + } + Ok(out) +} + +fn apply_ptm_to_operator( + ptm: &Ptm, + operator: &DMatrix, +) -> Result, ChannelError> { + let dim = hilbert_dim(ptm.num_qubits)?; + validate_complex_matrix(operator, dim, dim)?; + #[allow(clippy::cast_precision_loss)] + let dim_f = dim as f64; + let basis_matrices = pauli_basis_matrices(ptm.num_qubits)?; + let mut out = DMatrix::zeros(dim, dim); + for input_idx in 0..basis_matrices.len() { + let coefficient = trace_complex(&(&basis_matrices[input_idx] * operator)) / dim_f; + for (output_idx, basis_matrix) in basis_matrices.iter().enumerate() { + let output_coefficient = coefficient * ptm.entry(output_idx, input_idx); + out += basis_matrix * output_coefficient; + } + } + Ok(out) +} + +fn kraus_from_channel_expr_with_size( + channel: &ChannelExpr, + num_qubits: usize, +) -> Result { + match channel { + ChannelExpr::Unitary(unitary) => KrausOps::from_unitary(unitary, num_qubits), + ChannelExpr::MixedUnitary(ops) => { + let mut total_probability = 0.0; + let mut operators = Vec::with_capacity(ops.len()); + for (probability, unitary) in ops { + validate_probability(*probability, DEFAULT_TOLERANCE)?; + total_probability += *probability; + if *probability > DEFAULT_TOLERANCE { + let scale = Complex64::new(probability.sqrt(), 0.0); + operators.push(to_matrix_with_size(unitary, num_qubits).into_inner() * scale); + } + } + if (total_probability - 1.0).abs() > DEFAULT_TOLERANCE { + return Err(ChannelError::ProbabilitySum { + sum: total_probability, + tolerance: DEFAULT_TOLERANCE, + }); + } + KrausOps::try_new(num_qubits, operators) + } + ChannelExpr::AmplitudeDamping { gamma, qubit } => { + validate_unit_interval(*gamma)?; + let sqrt_survival = (1.0 - gamma).sqrt(); + let sqrt_decay = gamma.sqrt(); + let k0 = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(sqrt_survival, 0.0), + ], + ); + let k1 = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(sqrt_decay, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + KrausOps::try_new( + num_qubits, + vec![ + embed_single_qubit_operator(num_qubits, *qubit, &k0)?, + embed_single_qubit_operator(num_qubits, *qubit, &k1)?, + ], + ) + } + ChannelExpr::PhaseDamping { lambda, qubit } => { + validate_unit_interval(*lambda)?; + let sqrt_survival = (1.0 - lambda).sqrt(); + let sqrt_damp = lambda.sqrt(); + let k0 = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(sqrt_survival, 0.0), + ], + ); + let k1 = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(sqrt_damp, 0.0), + ], + ); + KrausOps::try_new( + num_qubits, + vec![ + embed_single_qubit_operator(num_qubits, *qubit, &k0)?, + embed_single_qubit_operator(num_qubits, *qubit, &k1)?, + ], + ) + } + ChannelExpr::Tensor(parts) => { + if parts.is_empty() { + return Err(ChannelError::UnsupportedChannelExpr { + reason: "empty channel tensor has no qubit context".to_string(), + }); + } + validate_disjoint_channel_parts(parts)?; + let mut operators = vec![DMatrix::::identity( + hilbert_dim(num_qubits)?, + hilbert_dim(num_qubits)?, + )]; + for part in parts { + let part_ops = kraus_from_channel_expr_with_size(part, num_qubits)?; + operators = compose_kraus_sets(&operators, part_ops.operators()); + } + KrausOps::try_new(num_qubits, operators) + } + ChannelExpr::Compose(parts) => { + if parts.is_empty() { + return Err(ChannelError::UnsupportedChannelExpr { + reason: "empty channel composition has no qubit context".to_string(), + }); + } + let dim = hilbert_dim(num_qubits)?; + let mut operators = vec![DMatrix::::identity(dim, dim)]; + for part in parts { + let part_ops = kraus_from_channel_expr_with_size(part, num_qubits)?; + operators = compose_kraus_sets(&operators, part_ops.operators()); + } + KrausOps::try_new(num_qubits, operators) + } + ChannelExpr::Gate(_) | ChannelExpr::Erasure { .. } | ChannelExpr::Leakage { .. } => { + Err(ChannelError::UnsupportedChannelExpr { + reason: + "gate instruments, erasure, and leakage need explicit outcome/flag semantics" + .to_string(), + }) + } + } +} + +fn validate_disjoint_channel_parts(parts: &[ChannelExpr]) -> Result<(), ChannelError> { + let mut seen = BTreeSet::new(); + for part in parts { + for qubit in part.qubits() { + if !seen.insert(qubit) { + return Err(ChannelError::DuplicateSubsystem { qubit }); + } + } + } + Ok(()) +} + +fn compose_kraus_sets( + current: &[DMatrix], + next: &[DMatrix], +) -> Vec> { + let mut out = Vec::with_capacity(current.len() * next.len()); + for next_op in next { + for current_op in current { + out.push(next_op * current_op); + } + } + out +} + +fn embed_single_qubit_operator( + num_qubits: usize, + qubit: usize, + local: &DMatrix, +) -> Result, ChannelError> { + if qubit >= num_qubits { + return Err(ChannelError::QubitOutOfRange { num_qubits, qubit }); + } + validate_complex_matrix(local, 2, 2)?; + + let dim = hilbert_dim(num_qubits)?; + let qubit_mask = 1usize << qubit; + let mut out = DMatrix::zeros(dim, dim); + for row in 0..dim { + for col in 0..dim { + if row & !qubit_mask == col & !qubit_mask { + let local_row = usize::from((row & qubit_mask) != 0); + let local_col = usize::from((col & qubit_mask) != 0); + out[(row, col)] = local[(local_row, local_col)]; + } + } + } + Ok(out) +} + +fn choi_index(dim: usize, output_index: usize, input_index: usize) -> usize { + output_index + input_index * dim +} + +fn trace_complex(matrix: &DMatrix) -> Complex64 { + let n = matrix.nrows().min(matrix.ncols()); + (0..n).map(|idx| matrix[(idx, idx)]).sum() +} + +fn hilbert_dim(num_qubits: usize) -> Result { + 2usize + .checked_pow( + num_qubits + .try_into() + .map_err(|_| ChannelError::DimensionOverflow { num_qubits })?, + ) + .ok_or(ChannelError::DimensionOverflow { num_qubits }) +} + +fn embed_subsystem_index( + kept_qubits: &[usize], + kept_index: usize, + traced_qubits: &[usize], + traced_index: usize, +) -> usize { + let mut out = 0usize; + for (bit, qubit) in kept_qubits.iter().copied().enumerate() { + if ((kept_index >> bit) & 1) != 0 { + out |= 1usize << qubit; + } + } + for (bit, qubit) in traced_qubits.iter().copied().enumerate() { + if ((traced_index >> bit) & 1) != 0 { + out |= 1usize << qubit; + } + } + out +} + +fn unitary_rep_to_pauli_bitmask( + num_qubits: usize, + unitary: &UnitaryRep, +) -> Result { + match unitary { + unitary if unitary.is_identity() => Ok(PauliBitmaskSmall::identity()), + UnitaryRep::Pauli(pauli) => { + // Global Pauli phase cancels in the induced channel U rho U†. + pauli_string_to_bitmask(num_qubits, pauli) + } + UnitaryRep::Tensor(parts) => { + let mut out = PauliBitmaskSmall::identity(); + for part in parts { + let part_mask = unitary_rep_to_pauli_bitmask(num_qubits, part)?; + out = out.multiply(&part_mask); + } + Ok(out) + } + _ => Err(ChannelError::UnsupportedChannelExpr { + reason: format!("unitary is not a Pauli operator: {unitary:?}"), + }), + } +} + +fn validate_num_qubits(num_qubits: usize, pauli: &PauliBitmaskSmall) -> Result<(), ChannelError> { + if let Some(qubit) = highest_qubit(pauli) + && qubit >= num_qubits + { + return Err(ChannelError::QubitOutOfRange { num_qubits, qubit }); + } + Ok(()) +} + +fn highest_qubit(pauli: &PauliBitmaskSmall) -> Option { + [ + pauli.x_bits.highest_set_bit(), + pauli.z_bits.highest_set_bit(), + ] + .into_iter() + .flatten() + .max() +} + +fn validate_complex(value: Complex64) -> Result<(), ChannelError> { + if value.re.is_finite() && value.im.is_finite() { + Ok(()) + } else { + Err(ChannelError::InvalidCoefficient { value }) + } +} + +fn validate_complex_matrix( + matrix: &DMatrix, + expected_rows: usize, + expected_cols: usize, +) -> Result<(), ChannelError> { + if matrix.nrows() != expected_rows || matrix.ncols() != expected_cols { + return Err(ChannelError::InvalidMatrixShape { + expected_rows, + expected_cols, + rows: matrix.nrows(), + cols: matrix.ncols(), + }); + } + for value in matrix.iter() { + validate_complex(*value)?; + } + Ok(()) +} + +fn validate_real(value: f64) -> Result<(), ChannelError> { + validate_complex(Complex64::new(value, 0.0)) +} + +fn validate_probability(value: f64, tolerance: f64) -> Result<(), ChannelError> { + validate_real(value)?; + if value < -tolerance { + return Err(ChannelError::InvalidProbability { value, tolerance }); + } + Ok(()) +} + +fn validate_unit_interval(value: f64) -> Result<(), ChannelError> { + validate_probability(value, DEFAULT_TOLERANCE)?; + if value > 1.0 + DEFAULT_TOLERANCE { + return Err(ChannelError::InvalidProbability { + value, + tolerance: DEFAULT_TOLERANCE, + }); + } + Ok(()) +} + +fn matrix_max_abs_diff(a: &DMatrix, b: &DMatrix) -> f64 { + if a.shape() != b.shape() { + return f64::INFINITY; + } + a.iter() + .zip(b.iter()) + .map(|(left, right)| (*left - *right).norm()) + .fold(0.0, f64::max) +} + +fn commutation_character(a: &PauliBitmaskSmall, b: &PauliBitmaskSmall) -> f64 { + if a.commutes_with(b) { 1.0 } else { -1.0 } +} + +#[cfg(test)] +mod tests { + use super::*; + use pecos_core::op; + use pecos_core::unitary; + use pecos_core::{Op, QuarterPhase}; + use pecos_random::PecosRng; + + fn assert_close(a: f64, b: f64) { + assert!((a - b).abs() < 1e-10, "{a} != {b}"); + } + + fn assert_complex_close(a: Complex64, b: Complex64) { + assert_close(a.re, b.re); + assert_close(a.im, b.im); + } + + fn assert_matrix_close(a: &DMatrix, b: &DMatrix) { + assert_eq!(a.shape(), b.shape()); + for row in 0..a.nrows() { + for col in 0..a.ncols() { + assert_close(a[(row, col)], b[(row, col)]); + } + } + } + + fn assert_complex_matrix_close(a: &DMatrix, b: &DMatrix) { + assert_eq!(a.shape(), b.shape()); + for row in 0..a.nrows() { + for col in 0..a.ncols() { + assert_complex_close(a[(row, col)], b[(row, col)]); + } + } + } + + fn assert_ptm_entry(ptm: &Ptm, output: &str, input: &str, expected: f64) { + let output_idx = labels(ptm.num_qubits()) + .iter() + .position(|label| label == output) + .unwrap(); + let input_idx = labels(ptm.num_qubits()) + .iter() + .position(|label| label == input) + .unwrap(); + assert_close(ptm.entry(output_idx, input_idx), expected); + } + + fn labels(num_qubits: usize) -> Vec { + (0..pauli_basis_len(num_qubits).unwrap()) + .map(|index| basis_label(num_qubits, index).unwrap()) + .collect() + } + + #[test] + fn one_qubit_basis_order_is_independent_of_pauli_discriminants() { + assert_eq!(Pauli::Z as u8, 0b10); + assert_eq!(Pauli::Y as u8, 0b11); + + assert_eq!(pauli_to_basis_digit(Pauli::I), 0); + assert_eq!(pauli_to_basis_digit(Pauli::X), 1); + assert_eq!(pauli_to_basis_digit(Pauli::Y), 2); + assert_eq!(pauli_to_basis_digit(Pauli::Z), 3); + + assert_eq!(labels(1), ["I", "X", "Y", "Z"]); + } + + #[test] + fn two_qubit_basis_order_is_little_endian_lexicographic() { + assert_eq!( + labels(2), + [ + "II", "IX", "IY", "IZ", "XI", "XX", "XY", "XZ", "YI", "YX", "YY", "YZ", "ZI", "ZX", + "ZY", "ZZ", + ] + ); + } + + #[test] + fn basis_bitmask_and_index_round_trip() { + for num_qubits in 1..=3 { + for index in 0..pauli_basis_len(num_qubits).unwrap() { + let pauli = basis_bitmask(num_qubits, index).unwrap(); + assert_eq!(basis_index(num_qubits, &pauli).unwrap(), index); + } + } + } + + #[test] + fn pauli_sum_add_scalar_simplify_and_trace() { + let identity = PauliBitmaskSmall::identity(); + let x0 = PauliBitmaskSmall::x(0); + + let mut a = PauliSum::new(1); + a.add_term(identity.clone(), Complex64::new(2.0, 0.0)) + .unwrap(); + a.add_term(x0.clone(), Complex64::new(1.0, 0.0)).unwrap(); + + let mut b = PauliSum::new(1); + b.add_term(x0.clone(), Complex64::new(-1.0, 0.0)).unwrap(); + b.add_term(PauliBitmaskSmall::z(0), Complex64::new(0.5, 0.0)) + .unwrap(); + + let c = (a + b) * 2.0; + assert_eq!(c.terms().len(), 2); + assert_complex_close(*c.terms().get(&identity).unwrap(), Complex64::new(4.0, 0.0)); + assert_complex_close(c.trace(), Complex64::new(8.0, 0.0)); + } + + #[test] + fn pauli_sum_from_pauli_string_preserves_phase_as_coefficient() { + let pauli = PauliString::with_phase_and_paulis( + QuarterPhase::PlusI, + vec![(Pauli::X, 0.into()), (Pauli::Z, 1.into())], + ); + let sum = PauliSum::from_pauli_string(2, &pauli).unwrap(); + let label = pauli_string_to_bitmask(2, &pauli).unwrap(); + assert_complex_close(*sum.terms().get(&label).unwrap(), Complex64::new(0.0, 1.0)); + assert_eq!(bitmask_label(2, &label).unwrap(), "ZX"); + } + + #[test] + fn pauli_string_conjugates_pauli_sum_terms() { + let mut sum = PauliSum::new(1); + sum.add_term(PauliBitmaskSmall::x(0), Complex64::new(2.0, 0.0)) + .unwrap(); + sum.add_term(PauliBitmaskSmall::z(0), Complex64::new(3.0, 0.0)) + .unwrap(); + + let conjugated = PauliString::z(0) * sum; + assert_complex_close( + *conjugated.terms().get(&PauliBitmaskSmall::x(0)).unwrap(), + Complex64::new(-2.0, 0.0), + ); + assert_complex_close( + *conjugated.terms().get(&PauliBitmaskSmall::z(0)).unwrap(), + Complex64::new(3.0, 0.0), + ); + } + + #[test] + fn qubit_count_errors_fail_construction() { + let mut terms = BTreeMap::new(); + terms.insert(PauliBitmaskSmall::x(2), Complex64::new(1.0, 0.0)); + let err = PauliSum::try_new(2, terms).unwrap_err(); + assert_eq!( + err, + ChannelError::QubitOutOfRange { + num_qubits: 2, + qubit: 2 + } + ); + } + + #[test] + fn one_qubit_pauli_channel_round_trips_through_diagonal_ptm() { + let channel = PauliChannel::one_qubit(0.1, 0.2, 0.3).unwrap(); + let diagonal = channel.to_diagonal_ptm().unwrap(); + + assert_close(diagonal.fidelity(&PauliBitmaskSmall::identity()), 1.0); + assert_close(diagonal.fidelity(&PauliBitmaskSmall::x(0)), 0.0); + assert_close(diagonal.fidelity(&PauliBitmaskSmall::y(0)), 0.2); + assert_close(diagonal.fidelity(&PauliBitmaskSmall::z(0)), 0.4); + + let recovered = diagonal.to_pauli_channel().unwrap(); + assert_close(recovered.probability(&PauliBitmaskSmall::identity()), 0.4); + assert_close(recovered.probability(&PauliBitmaskSmall::x(0)), 0.1); + assert_close(recovered.probability(&PauliBitmaskSmall::y(0)), 0.2); + assert_close(recovered.probability(&PauliBitmaskSmall::z(0)), 0.3); + assert_close(recovered.total_error_rate(), 0.6); + } + + #[test] + fn two_qubit_pauli_channel_round_trips_through_diagonal_ptm() { + let mut probabilities = BTreeMap::new(); + probabilities.insert(PauliBitmaskSmall::identity(), 0.7); + probabilities.insert(PauliBitmaskSmall::x(0), 0.1); + probabilities.insert(PauliBitmaskSmall::z(1), 0.05); + probabilities.insert( + PauliBitmaskSmall::y(0).multiply(&PauliBitmaskSmall::x(1)), + 0.15, + ); + + let channel = PauliChannel::try_new(2, probabilities).unwrap(); + let recovered = channel + .to_diagonal_ptm() + .unwrap() + .to_pauli_channel() + .unwrap(); + + assert_close(recovered.probability(&PauliBitmaskSmall::identity()), 0.7); + assert_close(recovered.probability(&PauliBitmaskSmall::x(0)), 0.1); + assert_close(recovered.probability(&PauliBitmaskSmall::z(1)), 0.05); + assert_close( + recovered.probability(&PauliBitmaskSmall::y(0).multiply(&PauliBitmaskSmall::x(1))), + 0.15, + ); + } + + #[test] + fn diagonal_ptm_values_are_not_probabilities() { + let mut fidelities = BTreeMap::new(); + fidelities.insert(PauliBitmaskSmall::identity(), 1.0); + fidelities.insert(PauliBitmaskSmall::x(0), -0.5); + fidelities.insert(PauliBitmaskSmall::y(0), 0.25); + fidelities.insert(PauliBitmaskSmall::z(0), 0.75); + + let diagonal = DiagonalPtm::try_new(1, fidelities.clone()).unwrap(); + assert_close(diagonal.fidelity(&PauliBitmaskSmall::x(0)), -0.5); + + let err = PauliChannel::try_new(1, fidelities).unwrap_err(); + assert!(matches!(err, ChannelError::InvalidProbability { .. })); + } + + #[test] + fn pauli_channel_from_pauli_sum_rejects_complex_or_negative_coefficients() { + let mut complex = PauliSum::new(1); + complex + .add_term(PauliBitmaskSmall::identity(), Complex64::new(1.0, 0.1)) + .unwrap(); + assert!(matches!( + PauliChannel::from_pauli_sum(&complex).unwrap_err(), + ChannelError::NonRealCoefficient { .. } + )); + + let mut negative_terms = BTreeMap::new(); + negative_terms.insert(PauliBitmaskSmall::identity(), -0.1); + negative_terms.insert(PauliBitmaskSmall::x(0), 1.1); + assert!(matches!( + PauliChannel::try_new(1, negative_terms).unwrap_err(), + ChannelError::InvalidProbability { .. } + )); + } + + #[test] + fn dense_ptm_identity_channel_is_identity_matrix() { + let ptm = Ptm::identity(2).unwrap(); + assert_eq!(ptm.matrix().nrows(), 16); + assert_eq!(ptm.matrix().ncols(), 16); + for row in 0..16 { + for col in 0..16 { + assert_close(ptm.entry(row, col), if row == col { 1.0 } else { 0.0 }); + } + } + } + + #[test] + fn dense_ptm_unitary_conjugation_known_one_qubit_cliffords() { + let h = Ptm::from_unitary(&unitary::H(0), 1).unwrap(); + assert_ptm_entry(&h, "I", "I", 1.0); + assert_ptm_entry(&h, "Z", "X", 1.0); + assert_ptm_entry(&h, "Y", "Y", -1.0); + assert_ptm_entry(&h, "X", "Z", 1.0); + + let s = Ptm::from_unitary(&unitary::SZ(0), 1).unwrap(); + assert_ptm_entry(&s, "I", "I", 1.0); + assert_ptm_entry(&s, "Y", "X", 1.0); + assert_ptm_entry(&s, "X", "Y", -1.0); + assert_ptm_entry(&s, "Z", "Z", 1.0); + + let x = Ptm::from_unitary(&unitary::X(0), 1).unwrap(); + assert_ptm_entry(&x, "I", "I", 1.0); + assert_ptm_entry(&x, "X", "X", 1.0); + assert_ptm_entry(&x, "Y", "Y", -1.0); + assert_ptm_entry(&x, "Z", "Z", -1.0); + } + + #[test] + fn dense_ptm_qubit_order_matches_unitary_matrix_little_endian() { + let x0 = Ptm::from_unitary(&(unitary::X(0) & unitary::I(1)), 2).unwrap(); + assert_ptm_entry(&x0, "IZ", "IZ", -1.0); + assert_ptm_entry(&x0, "ZI", "ZI", 1.0); + + let x1 = Ptm::from_unitary(&(unitary::I(0) & unitary::X(1)), 2).unwrap(); + assert_ptm_entry(&x1, "IZ", "IZ", 1.0); + assert_ptm_entry(&x1, "ZI", "ZI", -1.0); + } + + #[test] + fn invalid_dense_ptm_shape_fails_construction() { + let err = Ptm::try_new(1, DMatrix::zeros(3, 3)).unwrap_err(); + assert!(matches!(err, ChannelError::InvalidMatrixShape { .. })); + } + + #[test] + fn channel_expr_pauli_channel_conversions_handle_common_constructors() { + let Op::Channel(expr) = op::Depolarizing(0.3, 0) else { + panic!("expected channel"); + }; + let channel = PauliChannel::from_channel_expr(&expr).unwrap(); + assert_close(channel.probability(&PauliBitmaskSmall::identity()), 0.7); + assert_close(channel.probability(&PauliBitmaskSmall::x(0)), 0.1); + assert_close(channel.probability(&PauliBitmaskSmall::y(0)), 0.1); + assert_close(channel.probability(&PauliBitmaskSmall::z(0)), 0.1); + + let diagonal = DiagonalPtm::from_channel_expr(&expr).unwrap(); + let dense = Ptm::from_channel_expr(&expr).unwrap(); + assert_close(dense.entry(0, 0), 1.0); + assert_close( + dense.entry(1, 1), + diagonal.fidelity(&PauliBitmaskSmall::x(0)), + ); + } + + #[test] + fn kraus_unitary_ptm_matches_direct_unitary_ptm() { + let kraus = KrausOps::from_unitary(&unitary::H(0), 1).unwrap(); + assert_eq!(kraus.num_qubits(), 1); + assert_eq!(kraus.operators().len(), 1); + assert!(kraus.is_trace_preserving()); + + let from_kraus = kraus.to_ptm().unwrap(); + let direct = Ptm::from_unitary(&unitary::H(0), 1).unwrap(); + assert_matrix_close(from_kraus.matrix(), direct.matrix()); + } + + #[test] + fn kraus_mixed_unitary_ptm_matches_pauli_channel_ptm() { + let Op::Channel(expr) = op::Depolarizing(0.3, 0) else { + panic!("expected channel"); + }; + let kraus = KrausOps::from_channel_expr(&expr).unwrap(); + assert_eq!(kraus.operators().len(), 4); + assert!(kraus.is_trace_preserving()); + + let from_kraus = kraus.to_ptm().unwrap(); + let from_pauli = PauliChannel::from_channel_expr(&expr) + .unwrap() + .to_ptm() + .unwrap(); + assert_matrix_close(from_kraus.matrix(), from_pauli.matrix()); + } + + #[test] + fn amplitude_damping_kraus_and_ptm_have_known_values() { + let gamma = 0.25; + let Op::Channel(expr) = op::AmplitudeDamping(gamma, 0) else { + panic!("expected channel"); + }; + let kraus = KrausOps::from_channel_expr(&expr).unwrap(); + assert_eq!(kraus.operators().len(), 2); + assert!(kraus.is_trace_preserving()); + + let ptm = Ptm::from_channel_expr(&expr).unwrap(); + assert_ptm_entry(&ptm, "I", "I", 1.0); + assert_ptm_entry(&ptm, "Z", "I", gamma); + assert_ptm_entry(&ptm, "X", "X", (1.0 - gamma).sqrt()); + assert_ptm_entry(&ptm, "Y", "Y", (1.0 - gamma).sqrt()); + assert_ptm_entry(&ptm, "Z", "Z", 1.0 - gamma); + } + + #[test] + fn phase_damping_kraus_and_ptm_have_known_values() { + let lambda = 0.36; + let Op::Channel(expr) = op::PhaseDamping(lambda, 0) else { + panic!("expected channel"); + }; + let kraus = KrausOps::from_channel_expr(&expr).unwrap(); + assert_eq!(kraus.operators().len(), 2); + assert!(kraus.is_trace_preserving()); + + let ptm = Ptm::from_channel_expr(&expr).unwrap(); + assert_ptm_entry(&ptm, "I", "I", 1.0); + assert_ptm_entry(&ptm, "X", "X", (1.0 - lambda).sqrt()); + assert_ptm_entry(&ptm, "Y", "Y", (1.0 - lambda).sqrt()); + assert_ptm_entry(&ptm, "Z", "Z", 1.0); + assert_ptm_entry(&ptm, "Z", "I", 0.0); + } + + #[test] + fn kraus_tensor_and_compose_channels_are_trace_preserving() { + let tensor = ChannelExpr::Tensor(vec![ + ChannelExpr::AmplitudeDamping { + gamma: 0.2, + qubit: 0, + }, + ChannelExpr::PhaseDamping { + lambda: 0.3, + qubit: 1, + }, + ]); + let tensor_kraus = KrausOps::from_channel_expr(&tensor).unwrap(); + assert_eq!(tensor_kraus.num_qubits(), 2); + assert_eq!(tensor_kraus.operators().len(), 4); + assert!(tensor_kraus.is_trace_preserving()); + + let compose = ChannelExpr::Compose(vec![ + ChannelExpr::AmplitudeDamping { + gamma: 0.2, + qubit: 0, + }, + ChannelExpr::PhaseDamping { + lambda: 0.3, + qubit: 0, + }, + ]); + let compose_kraus = KrausOps::from_channel_expr(&compose).unwrap(); + assert_eq!(compose_kraus.num_qubits(), 1); + assert_eq!(compose_kraus.operators().len(), 4); + assert!(compose_kraus.is_trace_preserving()); + } + + #[test] + fn pauli_channel_conversion_ignores_global_pauli_phase() { + let pauli = PauliString::from_paulis_with_phase(QuarterPhase::PlusI, &[Pauli::X]); + let expr = ChannelExpr::Unitary(UnitaryRep::Pauli(pauli)); + + let channel = PauliChannel::from_channel_expr(&expr).unwrap(); + assert_close(channel.probability(&PauliBitmaskSmall::x(0)), 1.0); + + let dense = Ptm::from_channel_expr(&expr).unwrap(); + assert_ptm_entry(&dense, "X", "X", 1.0); + assert_ptm_entry(&dense, "Y", "Y", -1.0); + assert_ptm_entry(&dense, "Z", "Z", -1.0); + } + + #[test] + fn pauli_channel_rejects_non_pauli_channel_conversion() { + let Op::Channel(expr) = op::AmplitudeDamping(0.1, 0) else { + panic!("expected channel"); + }; + assert!(matches!( + PauliChannel::from_channel_expr(&expr).unwrap_err(), + ChannelError::UnsupportedChannelExpr { .. } + )); + assert!(Ptm::from_channel_expr(&expr).is_ok()); + } + + #[test] + fn kraus_rejects_channels_with_non_kraus_semantics() { + let Op::Gate(gate) = op::MZ(0) else { + panic!("expected gate"); + }; + let gate_expr = ChannelExpr::Gate(gate); + assert!(matches!( + KrausOps::from_channel_expr(&gate_expr).unwrap_err(), + ChannelError::UnsupportedChannelExpr { .. } + )); + + let Op::Channel(erasure) = op::Erasure(0.1, 0) else { + panic!("expected channel"); + }; + assert!(matches!( + KrausOps::from_channel_expr(&erasure).unwrap_err(), + ChannelError::UnsupportedChannelExpr { .. } + )); + + let Op::Channel(leakage) = op::Leakage(0.1, 0) else { + panic!("expected channel"); + }; + assert!(matches!( + KrausOps::from_channel_expr(&leakage).unwrap_err(), + ChannelError::UnsupportedChannelExpr { .. } + )); + } + + #[test] + fn choi_identity_uses_column_stacked_kraus_convention() { + let choi = ChoiMatrix::from_unitary(&unitary::I(0), 1).unwrap(); + assert_eq!(choi.num_qubits(), 1); + assert_eq!(choi.matrix().shape(), (4, 4)); + assert!(choi.is_trace_preserving()); + assert_complex_close(trace_complex(choi.matrix()), Complex64::new(2.0, 0.0)); + + let mut expected = DMatrix::zeros(4, 4); + expected[(0, 0)] = Complex64::new(1.0, 0.0); + expected[(0, 3)] = Complex64::new(1.0, 0.0); + expected[(3, 0)] = Complex64::new(1.0, 0.0); + expected[(3, 3)] = Complex64::new(1.0, 0.0); + assert_complex_matrix_close(choi.matrix(), &expected); + } + + #[test] + fn choi_ptm_round_trip_for_depolarizing_channel() { + let Op::Channel(expr) = op::Depolarizing(0.3, 0) else { + panic!("expected channel"); + }; + let ptm = Ptm::from_channel_expr(&expr).unwrap(); + let choi = ptm.to_choi().unwrap(); + assert!(choi.is_trace_preserving()); + + let recovered = choi.to_ptm().unwrap(); + assert_matrix_close(recovered.matrix(), ptm.matrix()); + } + + #[test] + fn choi_round_trips_amplitude_damping_through_kraus_and_ptm() { + let Op::Channel(expr) = op::AmplitudeDamping(0.25, 0) else { + panic!("expected channel"); + }; + let kraus = KrausOps::from_channel_expr(&expr).unwrap(); + let choi = kraus.to_choi().unwrap(); + assert!(choi.is_trace_preserving()); + + let ptm_from_kraus = kraus.to_ptm().unwrap(); + let ptm_from_choi = choi.to_ptm().unwrap(); + assert_matrix_close(ptm_from_choi.matrix(), ptm_from_kraus.matrix()); + + let recovered_kraus = choi.to_kraus().unwrap(); + assert!(recovered_kraus.is_trace_preserving()); + let recovered_ptm = recovered_kraus.to_ptm().unwrap(); + assert_matrix_close(recovered_ptm.matrix(), ptm_from_kraus.matrix()); + } + + #[test] + fn ptm_to_kraus_round_trip_for_unitary_channel() { + let ptm = Ptm::from_unitary(&unitary::H(0), 1).unwrap(); + let kraus = ptm.to_kraus().unwrap(); + assert!(kraus.is_trace_preserving()); + + let recovered = kraus.to_ptm().unwrap(); + assert_matrix_close(recovered.matrix(), ptm.matrix()); + } + + #[test] + fn invalid_choi_shape_fails_construction() { + let err = ChoiMatrix::try_new(1, DMatrix::zeros(2, 2)).unwrap_err(); + assert!(matches!(err, ChannelError::InvalidMatrixShape { .. })); + } + + #[test] + fn choi_to_kraus_rejects_non_positive_choi_matrix() { + let mut matrix = DMatrix::zeros(4, 4); + matrix[(0, 0)] = Complex64::new(1.0, 0.0); + matrix[(3, 3)] = Complex64::new(-1.0, 0.0); + let choi = ChoiMatrix::try_new(1, matrix).unwrap(); + + assert!(matches!( + choi.to_kraus().unwrap_err(), + ChannelError::DecompositionFailed { .. } + )); + } + + #[test] + fn choi_to_kraus_rejects_invalid_tolerance() { + let choi = ChoiMatrix::from_unitary(&unitary::I(0), 1).unwrap(); + + assert!(matches!( + choi.to_kraus_with_tolerance(f64::NAN).unwrap_err(), + ChannelError::DecompositionFailed { .. } + )); + assert!(matches!( + choi.to_kraus_with_tolerance(-1e-12).unwrap_err(), + ChannelError::DecompositionFailed { .. } + )); + } + + #[test] + fn partial_trace_of_bell_state_is_maximally_mixed() { + let half = Complex64::new(0.5, 0.0); + let mut rho = DMatrix::zeros(4, 4); + rho[(0, 0)] = half; + rho[(0, 3)] = half; + rho[(3, 0)] = half; + rho[(3, 3)] = half; + + let reduced = partial_trace(&rho, 2, &[1]).unwrap(); + assert_eq!(reduced.shape(), (2, 2)); + assert_complex_close(reduced[(0, 0)], half); + assert_complex_close(reduced[(1, 1)], half); + assert_complex_close(reduced[(0, 1)], Complex64::new(0.0, 0.0)); + assert_complex_close(reduced[(1, 0)], Complex64::new(0.0, 0.0)); + } + + #[test] + fn partial_trace_respects_little_endian_qubit_ordering() { + let mut rho = DMatrix::zeros(4, 4); + rho[(1, 1)] = Complex64::new(1.0, 0.0); // |q1=0, q0=1><...| + + let keep_q0 = partial_trace(&rho, 2, &[1]).unwrap(); + assert_complex_close(keep_q0[(0, 0)], Complex64::new(0.0, 0.0)); + assert_complex_close(keep_q0[(1, 1)], Complex64::new(1.0, 0.0)); + + let keep_q1 = partial_trace(&rho, 2, &[0]).unwrap(); + assert_complex_close(keep_q1[(0, 0)], Complex64::new(1.0, 0.0)); + assert_complex_close(keep_q1[(1, 1)], Complex64::new(0.0, 0.0)); + } + + #[test] + fn random_helpers_return_values_from_expected_sets() { + let mut rng = PecosRng::seed_from_u64(123); + let pauli = random_pauli(&mut rng, 5); + assert!(pauli.qubits().into_iter().all(|q| q < 5)); + + let c1 = random_1q_clifford(&mut rng); + assert!(Clifford::all_1q().contains(&c1)); + + let c2 = random_2q_clifford(&mut rng); + assert!(Clifford::all_2q().contains(&c2)); + + let c = random_clifford(&mut rng); + assert!(Clifford::all().contains(&c)); + } +} diff --git a/crates/pecos-quantum/src/dag_circuit.rs b/crates/pecos-quantum/src/dag_circuit.rs index 8f5b9e657..3a2ee6641 100644 --- a/crates/pecos-quantum/src/dag_circuit.rs +++ b/crates/pecos-quantum/src/dag_circuit.rs @@ -17,7 +17,7 @@ //! This module provides [`DagCircuit`], a directed acyclic graph representation //! of quantum circuits where nodes are gates and edges are qubit wires. //! -//! The design follows HUGR and Qiskit's `DAGCircuit`: edges represent qubit wires +//! The design follows a wire-edge DAG model: edges represent qubit wires //! flowing between gates, not just abstract dependencies. use std::collections::{BTreeMap, BTreeSet}; @@ -317,7 +317,7 @@ impl TraversalWorkBuffers { /// /// Each node in the DAG represents a quantum gate. Edges represent qubit wires /// flowing between gates - each edge is labeled with the [`QubitId`] it carries. -/// This design follows HUGR and Qiskit's `DAGCircuit`. +/// This design follows a wire-edge DAG model. /// /// For a two-qubit gate like CX, there are two incoming edges (one per qubit) /// and two outgoing edges. diff --git a/crates/pecos-quantum/src/lib.rs b/crates/pecos-quantum/src/lib.rs index 9d29a3672..241d83c32 100644 --- a/crates/pecos-quantum/src/lib.rs +++ b/crates/pecos-quantum/src/lib.rs @@ -63,9 +63,11 @@ //! circuit2.tick().mz(&[0, 1, 2, 3]); // Measure multiple qubits //! ``` +pub mod channel; mod circuit; mod circuit_display; mod dag_circuit; +pub mod measures; pub mod pass; pub mod pauli_group; pub mod pauli_sequence; @@ -97,8 +99,20 @@ pub use pecos_core::gate_type::GateType; pub use pecos_core::{ClassicalBitId, Gate, QubitId, TimeScale, TimeUnits}; pub use pecos_num::dag::DagWouldCycleError; +// Concrete channel representation types +pub use channel::{ + ChannelError, ChoiMatrix, DiagonalPtm, KrausOps, PauliChannel, PauliSum, Ptm, PtmBasisOrder, + basis_bitmask, basis_digit_to_pauli, basis_element, basis_index, basis_label, bitmask_label, + partial_trace, pauli_basis_len, pauli_string_to_bitmask, pauli_to_basis_digit, + random_1q_clifford, random_2q_clifford, random_clifford, random_pauli, +}; +pub use measures::{ + MeasureError, average_gate_fidelity, entropy, entropy_with_base, gate_error, process_fidelity, + purity, state_fidelity, state_fidelity_with_density_matrix, +}; + // Re-export operator matrix types for convenient method-style matrix conversion -pub use unitary_matrix::{ToMatrix, UnitaryMatrix}; +pub use unitary_matrix::{ToMatrix, UnitaryMatrix, UnitaryMatrixError, random_unitary}; // Pauli collection and stabilizer group types pub use pauli_group::{PauliGroup, PauliGroupError}; diff --git a/crates/pecos-quantum/src/measures.rs b/crates/pecos-quantum/src/measures.rs new file mode 100644 index 000000000..8e9831164 --- /dev/null +++ b/crates/pecos-quantum/src/measures.rs @@ -0,0 +1,499 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Standalone quantum information measures. +//! +//! Measures are free functions so they can be shared across simulator and +//! representation types without forcing every backend into a single state API. + +use std::error::Error; +use std::fmt; + +use nalgebra::{DMatrix, DVector, SVD}; +use num_complex::Complex64; + +use crate::channel::Ptm; + +const DEFAULT_TOLERANCE: f64 = 1e-12; + +/// Error returned by quantum-information measure functions. +#[derive(Debug, Clone, PartialEq)] +pub enum MeasureError { + /// The requested Hilbert-space dimension would overflow `usize`. + DimensionOverflow { + /// Number of qubits supplied by the caller. + num_qubits: usize, + }, + /// Two vectors have incompatible lengths. + VectorLengthMismatch { + /// Left vector length. + left: usize, + /// Right vector length. + right: usize, + }, + /// A matrix is not square. + NonSquareMatrix { + /// Actual row count. + rows: usize, + /// Actual column count. + cols: usize, + }, + /// A matrix does not have the expected shape. + InvalidMatrixShape { + /// Expected row count. + expected_rows: usize, + /// Expected column count. + expected_cols: usize, + /// Actual row count. + rows: usize, + /// Actual column count. + cols: usize, + }, + /// A value is not finite. + NonFiniteValue { + /// Offending value. + value: Complex64, + }, + /// A state vector is not normalized. + InvalidStateNorm { + /// Observed squared norm. + norm_sqr: f64, + /// Allowed absolute tolerance. + tolerance: f64, + }, + /// A density matrix is not Hermitian within tolerance. + NonHermitianMatrix { + /// Row index where the mismatch was observed. + row: usize, + /// Column index where the mismatch was observed. + col: usize, + /// Observed entry. + value: Complex64, + /// Conjugate-transposed entry. + adjoint_value: Complex64, + /// Allowed absolute tolerance. + tolerance: f64, + }, + /// A density matrix does not have trace one. + InvalidDensityTrace { + /// Observed trace. + trace: Complex64, + /// Allowed absolute tolerance. + tolerance: f64, + }, + /// The requested logarithm base is invalid for entropy. + InvalidEntropyBase { + /// Invalid base. + base: f64, + }, +} + +impl fmt::Display for MeasureError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + Self::DimensionOverflow { num_qubits } => { + write!( + f, + "Hilbert-space dimension overflows usize for {num_qubits} qubits" + ) + } + Self::VectorLengthMismatch { left, right } => { + write!(f, "vector length mismatch: {left} != {right}") + } + Self::NonSquareMatrix { rows, cols } => { + write!(f, "matrix must be square, got {rows}x{cols}") + } + Self::InvalidMatrixShape { + expected_rows, + expected_cols, + rows, + cols, + } => write!( + f, + "invalid matrix shape {rows}x{cols}; expected {expected_rows}x{expected_cols}" + ), + Self::NonFiniteValue { value } => write!(f, "non-finite value: {value}"), + Self::InvalidStateNorm { + norm_sqr, + tolerance, + } => write!( + f, + "state vector squared norm must be 1 within tolerance {tolerance}, got {norm_sqr}" + ), + Self::NonHermitianMatrix { + row, + col, + value, + adjoint_value, + tolerance, + } => write!( + f, + "matrix is not Hermitian within tolerance {tolerance} at ({row}, {col}): {value} != {adjoint_value}" + ), + Self::InvalidDensityTrace { trace, tolerance } => write!( + f, + "density matrix trace must be 1 within tolerance {tolerance}, got {trace}" + ), + Self::InvalidEntropyBase { base } => { + write!( + f, + "entropy logarithm base must be finite, positive, and not 1; got {base}" + ) + } + } + } +} + +impl Error for MeasureError {} + +/// Returns pure-state fidelity `||^2`. +/// +/// Both state vectors must have the same length and be normalized. +/// +/// # Errors +/// +/// Returns an error when lengths differ, entries are non-finite, or either +/// vector is not normalized within tolerance. +pub fn state_fidelity( + left: &DVector, + right: &DVector, +) -> Result { + if left.len() != right.len() { + return Err(MeasureError::VectorLengthMismatch { + left: left.len(), + right: right.len(), + }); + } + validate_state_vector(left)?; + validate_state_vector(right)?; + let overlap: Complex64 = left + .iter() + .zip(right.iter()) + .map(|(left, right)| left.conj() * right) + .sum(); + Ok(overlap.norm_sqr()) +} + +/// Returns fidelity `` between a density matrix and a pure state. +/// +/// `rho` must be a trace-one Hermitian density matrix and `psi` must be a +/// normalized state vector with matching dimension. Positive-semidefinite +/// validation is intentionally not part of this cheap structural check. +/// +/// # Errors +/// +/// Returns an error when dimensions differ or either input is structurally +/// invalid. +pub fn state_fidelity_with_density_matrix( + rho: &DMatrix, + psi: &DVector, +) -> Result { + validate_density_matrix(rho)?; + validate_state_vector(psi)?; + if rho.nrows() != psi.len() { + return Err(MeasureError::InvalidMatrixShape { + expected_rows: psi.len(), + expected_cols: psi.len(), + rows: rho.nrows(), + cols: rho.ncols(), + }); + } + let evolved = rho * psi; + let value: Complex64 = psi + .iter() + .zip(evolved.iter()) + .map(|(left, right)| left.conj() * right) + .sum(); + if value.im.abs() > DEFAULT_TOLERANCE { + return Err(MeasureError::NonFiniteValue { value }); + } + Ok(value.re) +} + +/// Returns density-matrix purity `Tr(rho^2)`. +/// +/// # Errors +/// +/// Returns an error when `rho` is not square, finite, Hermitian, and trace one. +pub fn purity(rho: &DMatrix) -> Result { + validate_density_matrix(rho)?; + let value = trace(&(rho * rho)); + if value.im.abs() > DEFAULT_TOLERANCE { + return Err(MeasureError::NonFiniteValue { value }); + } + Ok(value.re) +} + +/// Returns the von Neumann entropy `-Tr(rho log_2 rho)`. +/// +/// `rho` must be a positive-semidefinite density matrix. This function +/// validates the cheap structural conditions (square, finite, Hermitian, +/// trace one) and computes the entropy from singular values, which equal the +/// eigenvalues for valid density matrices. +/// +/// # Errors +/// +/// Returns an error when `rho` is structurally invalid. +pub fn entropy(rho: &DMatrix) -> Result { + entropy_with_base(rho, 2.0) +} + +/// Returns the von Neumann entropy `-Tr(rho log_base rho)`. +/// +/// # Errors +/// +/// Returns an error when `rho` is structurally invalid or `base` is not finite, +/// positive, and different from one. +pub fn entropy_with_base(rho: &DMatrix, base: f64) -> Result { + validate_density_matrix(rho)?; + validate_entropy_base(base)?; + let svd = SVD::new(rho.clone(), false, false); + let log_base = base.ln(); + Ok(svd + .singular_values + .iter() + .copied() + .filter(|lambda| *lambda > DEFAULT_TOLERANCE) + .map(|lambda| -lambda * lambda.ln() / log_base) + .sum()) +} + +/// Returns normalized process fidelity between two PTMs. +/// +/// With PECOS's normalized Pauli basis convention, this is +/// `Tr(R_left^T R_right) / 4^n`. Identity compared with identity gives 1. +/// +/// # Errors +/// +/// Returns an error when the PTMs have different qubit counts. +pub fn process_fidelity(left: &Ptm, right: &Ptm) -> Result { + if left.num_qubits() != right.num_qubits() { + return Err(MeasureError::InvalidMatrixShape { + expected_rows: left.matrix().nrows(), + expected_cols: left.matrix().ncols(), + rows: right.matrix().nrows(), + cols: right.matrix().ncols(), + }); + } + #[allow(clippy::cast_precision_loss)] + let basis_len = left.matrix().nrows() as f64; + let value: f64 = left + .matrix() + .iter() + .zip(right.matrix().iter()) + .map(|(left, right)| left * right) + .sum::() + / basis_len; + Ok(value) +} + +/// Returns average gate fidelity between two PTMs. +/// +/// This uses `F_avg = (d F_process + 1) / (d + 1)` for Hilbert-space +/// dimension `d = 2^n`. +/// +/// # Errors +/// +/// Returns an error when the PTMs have different qubit counts or the Hilbert +/// dimension overflows. +pub fn average_gate_fidelity(left: &Ptm, right: &Ptm) -> Result { + let process = process_fidelity(left, right)?; + let dim = hilbert_dim(left.num_qubits())?; + #[allow(clippy::cast_precision_loss)] + let dim = dim as f64; + Ok((dim * process + 1.0) / (dim + 1.0)) +} + +/// Returns average gate error `1 - average_gate_fidelity`. +/// +/// # Errors +/// +/// Returns an error when [`average_gate_fidelity`] fails. +pub fn gate_error(left: &Ptm, right: &Ptm) -> Result { + Ok(1.0 - average_gate_fidelity(left, right)?) +} + +fn validate_state_vector(vector: &DVector) -> Result<(), MeasureError> { + let mut norm_sqr = 0.0; + for value in vector.iter() { + validate_complex(*value)?; + norm_sqr += value.norm_sqr(); + } + if (norm_sqr - 1.0).abs() > DEFAULT_TOLERANCE { + return Err(MeasureError::InvalidStateNorm { + norm_sqr, + tolerance: DEFAULT_TOLERANCE, + }); + } + Ok(()) +} + +fn validate_density_matrix(matrix: &DMatrix) -> Result<(), MeasureError> { + if matrix.nrows() != matrix.ncols() { + return Err(MeasureError::NonSquareMatrix { + rows: matrix.nrows(), + cols: matrix.ncols(), + }); + } + for value in matrix.iter() { + validate_complex(*value)?; + } + for row in 0..matrix.nrows() { + for col in 0..matrix.ncols() { + let value = matrix[(row, col)]; + let adjoint_value = matrix[(col, row)].conj(); + if (value - adjoint_value).norm() > DEFAULT_TOLERANCE { + return Err(MeasureError::NonHermitianMatrix { + row, + col, + value, + adjoint_value, + tolerance: DEFAULT_TOLERANCE, + }); + } + } + } + let trace = trace(matrix); + if trace.im.abs() > DEFAULT_TOLERANCE || (trace.re - 1.0).abs() > DEFAULT_TOLERANCE { + return Err(MeasureError::InvalidDensityTrace { + trace, + tolerance: DEFAULT_TOLERANCE, + }); + } + Ok(()) +} + +fn validate_complex(value: Complex64) -> Result<(), MeasureError> { + if value.re.is_finite() && value.im.is_finite() { + Ok(()) + } else { + Err(MeasureError::NonFiniteValue { value }) + } +} + +fn validate_entropy_base(base: f64) -> Result<(), MeasureError> { + if base.is_finite() && base > 0.0 && (base - 1.0).abs() > DEFAULT_TOLERANCE { + Ok(()) + } else { + Err(MeasureError::InvalidEntropyBase { base }) + } +} + +fn trace(matrix: &DMatrix) -> Complex64 { + let n = matrix.nrows().min(matrix.ncols()); + (0..n).map(|idx| matrix[(idx, idx)]).sum() +} + +fn hilbert_dim(num_qubits: usize) -> Result { + 2usize + .checked_pow( + num_qubits + .try_into() + .map_err(|_| MeasureError::DimensionOverflow { num_qubits })?, + ) + .ok_or(MeasureError::DimensionOverflow { num_qubits }) +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::channel::Ptm; + use pecos_core::{Op, op}; + + fn assert_close(a: f64, b: f64) { + assert!((a - b).abs() < 1e-10, "{a} != {b}"); + } + + fn ket(values: &[Complex64]) -> DVector { + DVector::from_column_slice(values) + } + + fn pure_density(psi: &DVector) -> DMatrix { + psi * psi.adjoint() + } + + #[test] + fn pure_state_fidelity_matches_known_values() { + let zero = ket(&[Complex64::new(1.0, 0.0), Complex64::new(0.0, 0.0)]); + let one = ket(&[Complex64::new(0.0, 0.0), Complex64::new(1.0, 0.0)]); + let plus = ket(&[ + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + ]); + + assert_close(state_fidelity(&zero, &zero).unwrap(), 1.0); + assert_close(state_fidelity(&zero, &one).unwrap(), 0.0); + assert_close(state_fidelity(&zero, &plus).unwrap(), 0.5); + } + + #[test] + fn state_fidelity_rejects_unnormalized_vectors() { + let zero = ket(&[Complex64::new(1.0, 0.0), Complex64::new(0.0, 0.0)]); + let bad = ket(&[Complex64::new(1.0, 0.0), Complex64::new(1.0, 0.0)]); + + assert!(matches!( + state_fidelity(&zero, &bad).unwrap_err(), + MeasureError::InvalidStateNorm { .. } + )); + } + + #[test] + fn density_matrix_purity_and_entropy_match_known_states() { + let zero = ket(&[Complex64::new(1.0, 0.0), Complex64::new(0.0, 0.0)]); + let pure = pure_density(&zero); + let half = Complex64::new(0.5, 0.0); + let mixed = DMatrix::from_diagonal_element(2, 2, half); + + assert_close(purity(&pure).unwrap(), 1.0); + assert_close(entropy(&pure).unwrap(), 0.0); + assert_close(purity(&mixed).unwrap(), 0.5); + assert_close(entropy(&mixed).unwrap(), 1.0); + assert_close( + state_fidelity_with_density_matrix(&mixed, &zero).unwrap(), + 0.5, + ); + } + + #[test] + fn density_matrix_measures_reject_invalid_matrices() { + let non_square = DMatrix::from_element(2, 3, Complex64::new(0.0, 0.0)); + assert!(matches!( + purity(&non_square).unwrap_err(), + MeasureError::NonSquareMatrix { .. } + )); + + let mut non_hermitian = DMatrix::zeros(2, 2); + non_hermitian[(0, 0)] = Complex64::new(1.0, 0.0); + non_hermitian[(0, 1)] = Complex64::new(0.1, 0.0); + assert!(matches!( + purity(&non_hermitian).unwrap_err(), + MeasureError::NonHermitianMatrix { .. } + )); + } + + #[test] + fn process_and_average_gate_fidelity_match_depolarizing_channel() { + let identity = Ptm::identity(1).unwrap(); + let Op::Channel(expr) = op::Depolarizing(0.3, 0) else { + panic!("expected channel"); + }; + let depolarizing = Ptm::from_channel_expr(&expr).unwrap(); + + assert_close(process_fidelity(&identity, &identity).unwrap(), 1.0); + assert_close(process_fidelity(&depolarizing, &identity).unwrap(), 0.7); + assert_close( + average_gate_fidelity(&depolarizing, &identity).unwrap(), + 0.8, + ); + assert_close(gate_error(&depolarizing, &identity).unwrap(), 0.2); + } +} diff --git a/crates/pecos-quantum/src/unitary_matrix.rs b/crates/pecos-quantum/src/unitary_matrix.rs index 38e36b4d4..bdc53dcc3 100644 --- a/crates/pecos-quantum/src/unitary_matrix.rs +++ b/crates/pecos-quantum/src/unitary_matrix.rs @@ -31,6 +31,9 @@ use nalgebra::DMatrix; use num_complex::Complex64; +use pecos_random::{Rng, RngExt as _}; +use std::error::Error; +use std::f64::consts::TAU; use std::fmt; use std::ops::{BitAnd, Deref, DerefMut, Mul, Neg, Sub}; use std::sync::LazyLock; @@ -70,6 +73,30 @@ use pecos_core::{Angle64, Op, Pauli, PauliString, Phase}; #[derive(Debug, Clone, PartialEq)] pub struct UnitaryMatrix(pub DMatrix); +/// Error returned by dense unitary-matrix helpers. +#[derive(Debug, Clone, PartialEq, Eq)] +pub enum UnitaryMatrixError { + /// The requested number of qubits would overflow a dense Hilbert-space + /// dimension. + DimensionOverflow { + /// Number of qubits supplied by the caller. + num_qubits: usize, + }, +} + +impl fmt::Display for UnitaryMatrixError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + Self::DimensionOverflow { num_qubits } => write!( + f, + "dense unitary dimension overflows usize for {num_qubits} qubits" + ), + } + } +} + +impl Error for UnitaryMatrixError {} + impl UnitaryMatrix { /// Creates an identity matrix of size `n x n`. #[must_use] @@ -192,6 +219,70 @@ impl UnitaryMatrix { } } +/// Returns a Haar-random dense unitary on `num_qubits` qubits. +/// +/// The implementation samples a complex Ginibre matrix, performs QR +/// decomposition, and fixes the column phases from the `R` diagonal. The output +/// is a dense matrix in the same little-endian computational-basis convention as +/// the rest of PECOS's matrix helpers. +/// +/// # Errors +/// +/// Returns [`UnitaryMatrixError::DimensionOverflow`] if `2^num_qubits` does not +/// fit in `usize`. +pub fn random_unitary( + rng: &mut R, + num_qubits: usize, +) -> Result +where + R: Rng + ?Sized, +{ + let dim = dense_hilbert_dim(num_qubits)?; + let ginibre = DMatrix::from_fn(dim, dim, |_, _| standard_complex_normal(rng)); + let (mut q, r) = ginibre.qr().unpack(); + + for col in 0..dim { + let diagonal = r[(col, col)]; + let norm = diagonal.norm(); + if norm > 0.0 { + let phase = diagonal / norm; + for row in 0..dim { + q[(row, col)] *= phase; + } + } + } + + Ok(UnitaryMatrix(q)) +} + +fn dense_hilbert_dim(num_qubits: usize) -> Result { + let exponent = u32::try_from(num_qubits) + .map_err(|_| UnitaryMatrixError::DimensionOverflow { num_qubits })?; + 2usize + .checked_pow(exponent) + .ok_or(UnitaryMatrixError::DimensionOverflow { num_qubits }) +} + +fn standard_complex_normal(rng: &mut R) -> Complex64 +where + R: Rng + ?Sized, +{ + Complex64::new(standard_normal(rng), standard_normal(rng)) +} + +fn standard_normal(rng: &mut R) -> f64 +where + R: Rng + ?Sized, +{ + loop { + let u1 = rng.random::(); + if u1 > 0.0 { + let u2 = rng.random::(); + return (-2.0 * u1.ln()).sqrt() * (TAU * u2).cos(); + } + } +} + // --- Canonicalization and cached lookup tables --- /// Divides all entries by the first nonzero entry (row-major scan). @@ -1921,6 +2012,7 @@ mod tests { use super::*; use pecos_core::Angle64; use pecos_core::unitary_rep::{CX, H, I, Is, RX, RZ, SWAP, SZ, T, X, Y, Z}; + use pecos_random::PecosRng; use std::f64::consts::PI; // --- Basic to_matrix tests --- @@ -3117,6 +3209,32 @@ mod tests { assert!(!mat.is_unitary()); } + #[test] + fn random_unitary_is_unitary_and_seed_reproducible() { + let mut rng = PecosRng::seed_from_u64(123); + let unitary = random_unitary(&mut rng, 2).unwrap(); + assert_eq!(unitary.inner().shape(), (4, 4)); + assert!(unitary.is_unitary_with_tolerance(1e-10)); + + let mut same_seed = PecosRng::seed_from_u64(123); + let same = random_unitary(&mut same_seed, 2).unwrap(); + assert_eq!(unitary.inner(), same.inner()); + + let mut different_seed = PecosRng::seed_from_u64(456); + let different = random_unitary(&mut different_seed, 2).unwrap(); + assert!( + !matrices_approx_equal(unitary.inner(), different.inner(), 1e-8), + "different seeds should not produce the same Haar draw" + ); + } + + #[test] + fn random_unitary_dimension_overflow_is_reported() { + let mut rng = PecosRng::seed_from_u64(123); + let err = random_unitary(&mut rng, usize::BITS as usize).unwrap_err(); + assert!(matches!(err, UnitaryMatrixError::DimensionOverflow { .. })); + } + #[test] fn try_to_unitary_rxxryyrzz_stress() { // Test a grid of angle combinations including edge cases: diff --git a/crates/pecos-simulators/src/bitmask_pauli_prop.rs b/crates/pecos-simulators/src/bitmask_pauli_prop.rs new file mode 100644 index 000000000..19b957215 --- /dev/null +++ b/crates/pecos-simulators/src/bitmask_pauli_prop.rs @@ -0,0 +1,664 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Bitmask-backed Pauli propagation for hot Clifford fault-analysis paths. +//! +//! This type tracks only the binary X/Z support of a propagating Pauli. It +//! intentionally ignores global phase, matching the fault-catalog use case +//! where only measurement flips and anticommutation with tracked operators +//! matter. + +use crate::clifford_gateable::{CliffordGateable, MeasurementResult}; +use crate::quantum_simulator::QuantumSimulator; +use pecos_core::{BitmaskStorage, PauliBitmaskSmall, QubitId}; + +/// A phase-free Pauli propagator backed by `PauliBitmaskSmall`. +#[derive(Clone, Debug)] +pub struct BitmaskPauliProp { + label: PauliBitmaskSmall, + num_qubits: usize, +} + +impl Default for BitmaskPauliProp { + fn default() -> Self { + Self::new() + } +} + +impl BitmaskPauliProp { + /// Create an empty propagating Pauli with no fixed qubit count. + #[must_use] + pub fn new() -> Self { + Self { + label: PauliBitmaskSmall::identity(), + num_qubits: 0, + } + } + + /// Create an empty propagating Pauli with a fixed qubit count for display + /// and tests. + #[must_use] + pub fn with_num_qubits(num_qubits: usize) -> Self { + Self { + label: PauliBitmaskSmall::identity(), + num_qubits, + } + } + + /// Checks whether the specified qubit has an X component. + #[inline] + #[must_use] + pub fn contains_x(&self, qubit: usize) -> bool { + self.label.x_bits.get_bit(qubit) + } + + /// Checks whether the specified qubit has a Z component. + #[inline] + #[must_use] + pub fn contains_z(&self, qubit: usize) -> bool { + self.label.z_bits.get_bit(qubit) + } + + /// Checks whether the specified qubit has a Y component. + #[inline] + #[must_use] + pub fn contains_y(&self, qubit: usize) -> bool { + self.contains_x(qubit) && self.contains_z(qubit) + } + + /// Toggle X components on the given qubits. + #[inline] + pub fn track_x(&mut self, qubits: &[usize]) { + for &q in qubits { + self.label.x_bits.xor_bit(q); + self.num_qubits = self.num_qubits.max(q + 1); + } + } + + /// Toggle Z components on the given qubits. + #[inline] + pub fn track_z(&mut self, qubits: &[usize]) { + for &q in qubits { + self.label.z_bits.xor_bit(q); + self.num_qubits = self.num_qubits.max(q + 1); + } + } + + /// Toggle Y components on the given qubits. + #[inline] + pub fn track_y(&mut self, qubits: &[usize]) { + for &q in qubits { + self.label.x_bits.xor_bit(q); + self.label.z_bits.xor_bit(q); + self.num_qubits = self.num_qubits.max(q + 1); + } + } + + /// Remove all Pauli components from one qubit. + #[inline] + pub fn clear_qubit(&mut self, qubit: usize) { + self.label.x_bits.clear_bit(qubit); + self.label.z_bits.clear_bit(qubit); + } + + /// True when no X/Z components remain. + #[inline] + #[must_use] + pub fn is_identity(&self) -> bool { + self.label.is_identity() + } + + /// Number of non-identity single-qubit factors. + #[must_use] + pub fn weight(&self) -> usize { + self.label.weight() as usize + } + + /// Dense string representation in qubit-index order. + #[must_use] + pub fn dense_string(&self) -> String { + let mut result = String::with_capacity(self.num_qubits); + for q in 0..self.num_qubits { + match (self.contains_x(q), self.contains_z(q)) { + (false, false) => result.push('I'), + (true, false) => result.push('X'), + (false, true) => result.push('Z'), + (true, true) => result.push('Y'), + } + } + result + } + + #[inline] + fn set_x_component(&mut self, q: usize, value: bool) { + if value { + self.label.x_bits.set_bit(q); + } else { + self.label.x_bits.clear_bit(q); + } + self.num_qubits = self.num_qubits.max(q + 1); + } + + #[inline] + fn set_z_component(&mut self, q: usize, value: bool) { + if value { + self.label.z_bits.set_bit(q); + } else { + self.label.z_bits.clear_bit(q); + } + self.num_qubits = self.num_qubits.max(q + 1); + } + + #[inline] + fn set_components(&mut self, q: usize, x: bool, z: bool) { + self.set_x_component(q, x); + self.set_z_component(q, z); + } +} + +impl QuantumSimulator for BitmaskPauliProp { + #[inline] + fn reset(&mut self) -> &mut Self { + self.label = PauliBitmaskSmall::identity(); + self + } + + fn num_qubits(&self) -> usize { + self.num_qubits + } +} + +impl CliffordGateable for BitmaskPauliProp { + #[inline] + fn sz(&mut self, qubits: &[QubitId]) -> &mut Self { + for &q in qubits { + let q = q.index(); + if self.contains_x(q) { + self.label.z_bits.xor_bit(q); + } + self.num_qubits = self.num_qubits.max(q + 1); + } + self + } + + #[inline] + fn szdg(&mut self, qubits: &[QubitId]) -> &mut Self { + self.sz(qubits) + } + + #[inline] + fn h(&mut self, qubits: &[QubitId]) -> &mut Self { + for &q in qubits { + let q = q.index(); + let x = self.contains_x(q); + let z = self.contains_z(q); + self.set_components(q, z, x); + } + self + } + + #[inline] + fn sx(&mut self, qubits: &[QubitId]) -> &mut Self { + for &q in qubits { + let q = q.index(); + if self.contains_z(q) { + self.label.x_bits.xor_bit(q); + } + self.num_qubits = self.num_qubits.max(q + 1); + } + self + } + + #[inline] + fn sxdg(&mut self, qubits: &[QubitId]) -> &mut Self { + self.sx(qubits) + } + + #[inline] + fn sy(&mut self, qubits: &[QubitId]) -> &mut Self { + for &q in qubits { + let q = q.index(); + let x = self.contains_x(q); + let z = self.contains_z(q); + self.set_components(q, z, x); + } + self + } + + #[inline] + fn sydg(&mut self, qubits: &[QubitId]) -> &mut Self { + self.sy(qubits) + } + + #[inline] + fn cx(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(control, target) in pairs { + let control = control.index(); + let target = target.index(); + let control_x = self.contains_x(control); + let target_z = self.contains_z(target); + if control_x { + self.label.x_bits.xor_bit(target); + } + if target_z { + self.label.z_bits.xor_bit(control); + } + self.num_qubits = self.num_qubits.max(control.max(target) + 1); + } + self + } + + #[inline] + fn cy(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + self.set_components(q1, x1, z1 ^ x2 ^ z2); + self.set_components(q2, x2 ^ x1, z2 ^ x1); + } + self + } + + #[inline] + fn cz(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + self.set_components(q1, x1, z1 ^ x2); + self.set_components(q2, x2, z2 ^ x1); + } + self + } + + #[inline] + fn sxx(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + let affected = z1 ^ z2; + self.set_components(q1, x1 ^ affected, z1); + self.set_components(q2, x2 ^ affected, z2); + } + self + } + + #[inline] + fn sxxdg(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + self.sxx(pairs) + } + + #[inline] + fn syy(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + self.set_components(q1, x2 ^ z1 ^ z2, x1 ^ x2 ^ z2); + self.set_components(q2, x1 ^ z1 ^ z2, x1 ^ x2 ^ z1); + } + self + } + + #[inline] + fn syydg(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + self.syy(pairs) + } + + #[inline] + fn szz(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + let affected = x1 ^ x2; + self.set_components(q1, x1, z1 ^ affected); + self.set_components(q2, x2, z2 ^ affected); + } + self + } + + #[inline] + fn szzdg(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + self.szz(pairs) + } + + #[inline] + fn swap(&mut self, pairs: &[(QubitId, QubitId)]) -> &mut Self { + for &(q1, q2) in pairs { + let q1 = q1.index(); + let q2 = q2.index(); + let x1 = self.contains_x(q1); + let z1 = self.contains_z(q1); + let x2 = self.contains_x(q2); + let z2 = self.contains_z(q2); + self.set_components(q1, x2, z2); + self.set_components(q2, x1, z1); + } + self + } + + #[inline] + fn mz(&mut self, qubits: &[QubitId]) -> Vec { + qubits + .iter() + .map(|&q| MeasurementResult { + outcome: self.contains_x(q.index()), + is_deterministic: true, + }) + .collect() + } +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::pauli_prop::PauliProp; + use pecos_core::QubitId; + + fn all_paulis(num_qubits: usize) -> Vec { + let labels = ['I', 'X', 'Y', 'Z']; + let mut out = Vec::new(); + let total = 4usize.pow(num_qubits.try_into().expect("test qubit count fits")); + for mut value in 0..total { + let mut s = String::with_capacity(num_qubits); + for _ in 0..num_qubits { + s.push(labels[value % 4]); + value /= 4; + } + out.push(s); + } + out + } + + fn sparse_prop_from_dense(input: &str) -> PauliProp { + let mut prop = PauliProp::with_sign_tracking(input.len()); + for (q, p) in input.chars().enumerate() { + match p { + 'I' => {} + 'X' => prop.track_x(&[q]), + 'Y' => prop.track_y(&[q]), + 'Z' => prop.track_z(&[q]), + _ => panic!("invalid Pauli label {p}"), + } + } + prop + } + + fn bitmask_prop_from_dense(input: &str) -> BitmaskPauliProp { + let mut prop = BitmaskPauliProp::with_num_qubits(input.len()); + for (q, p) in input.chars().enumerate() { + match p { + 'I' => {} + 'X' => prop.track_x(&[q]), + 'Y' => prop.track_y(&[q]), + 'Z' => prop.track_z(&[q]), + _ => panic!("invalid Pauli label {p}"), + } + } + prop + } + + fn assert_matches_sparse_1q(name: &str, mut apply_sparse: F, mut apply_bitmask: G) + where + F: FnMut(&mut PauliProp), + G: FnMut(&mut BitmaskPauliProp), + { + for input in all_paulis(1) { + let mut sparse = sparse_prop_from_dense(&input); + let mut bitmask = bitmask_prop_from_dense(&input); + apply_sparse(&mut sparse); + apply_bitmask(&mut bitmask); + assert_eq!( + bitmask.dense_string(), + sparse.dense_string(), + "{name}: {input}" + ); + } + } + + fn assert_matches_sparse_2q(name: &str, mut apply_sparse: F, mut apply_bitmask: G) + where + F: FnMut(&mut PauliProp, &[(QubitId, QubitId)]), + G: FnMut(&mut BitmaskPauliProp, &[(QubitId, QubitId)]), + { + let pair = [(QubitId(0), QubitId(1))]; + for input in all_paulis(2) { + let mut sparse = sparse_prop_from_dense(&input); + let mut bitmask = bitmask_prop_from_dense(&input); + apply_sparse(&mut sparse, &pair); + apply_bitmask(&mut bitmask, &pair); + assert_eq!( + bitmask.dense_string(), + sparse.dense_string(), + "{name}: {input}" + ); + } + } + + #[test] + fn single_qubit_cliffords_match_sparse_pauli_prop() { + assert_matches_sparse_1q( + "H", + |p| { + p.h(&[QubitId(0)]); + }, + |p| { + p.h(&[QubitId(0)]); + }, + ); + assert_matches_sparse_1q( + "SZ", + |p| { + p.sz(&[QubitId(0)]); + }, + |p| { + p.sz(&[QubitId(0)]); + }, + ); + assert_matches_sparse_1q( + "SZdg", + |p| { + p.szdg(&[QubitId(0)]); + }, + |p| { + p.szdg(&[QubitId(0)]); + }, + ); + assert_matches_sparse_1q( + "SX", + |p| { + p.sx(&[QubitId(0)]); + }, + |p| { + p.sx(&[QubitId(0)]); + }, + ); + assert_matches_sparse_1q( + "SXdg", + |p| { + p.sxdg(&[QubitId(0)]); + }, + |p| { + p.sxdg(&[QubitId(0)]); + }, + ); + assert_matches_sparse_1q( + "SY", + |p| { + p.sy(&[QubitId(0)]); + }, + |p| { + p.sy(&[QubitId(0)]); + }, + ); + assert_matches_sparse_1q( + "SYdg", + |p| { + p.sydg(&[QubitId(0)]); + }, + |p| { + p.sydg(&[QubitId(0)]); + }, + ); + assert_matches_sparse_1q( + "F", + |p| { + p.f(&[QubitId(0)]); + }, + |p| { + p.f(&[QubitId(0)]); + }, + ); + assert_matches_sparse_1q( + "Fdg", + |p| { + p.fdg(&[QubitId(0)]); + }, + |p| { + p.fdg(&[QubitId(0)]); + }, + ); + } + + #[test] + fn two_qubit_cliffords_match_sparse_pauli_prop() { + assert_matches_sparse_2q( + "CX", + |p, qs| { + p.cx(qs); + }, + |p, qs| { + p.cx(qs); + }, + ); + assert_matches_sparse_2q( + "CY", + |p, qs| { + p.cy(qs); + }, + |p, qs| { + p.cy(qs); + }, + ); + assert_matches_sparse_2q( + "CZ", + |p, qs| { + p.cz(qs); + }, + |p, qs| { + p.cz(qs); + }, + ); + assert_matches_sparse_2q( + "SXX", + |p, qs| { + p.sxx(qs); + }, + |p, qs| { + p.sxx(qs); + }, + ); + assert_matches_sparse_2q( + "SXXdg", + |p, qs| { + p.sxxdg(qs); + }, + |p, qs| { + p.sxxdg(qs); + }, + ); + assert_matches_sparse_2q( + "SYY", + |p, qs| { + p.syy(qs); + }, + |p, qs| { + p.syy(qs); + }, + ); + assert_matches_sparse_2q( + "SYYdg", + |p, qs| { + p.syydg(qs); + }, + |p, qs| { + p.syydg(qs); + }, + ); + assert_matches_sparse_2q( + "SZZ", + |p, qs| { + p.szz(qs); + }, + |p, qs| { + p.szz(qs); + }, + ); + assert_matches_sparse_2q( + "SZZdg", + |p, qs| { + p.szzdg(qs); + }, + |p, qs| { + p.szzdg(qs); + }, + ); + assert_matches_sparse_2q( + "SWAP", + |p, qs| { + p.swap(qs); + }, + |p, qs| { + p.swap(qs); + }, + ); + } + + #[test] + fn measurement_reset_and_identity_match_fault_catalog_semantics() { + let mut prop = BitmaskPauliProp::with_num_qubits(3); + prop.track_y(&[1]); + + let meas = prop.mz(&[QubitId(0), QubitId(1), QubitId(2)]); + assert_eq!( + meas.iter().map(|m| m.outcome).collect::>(), + vec![false, true, false] + ); + assert!(meas.iter().all(|m| m.is_deterministic)); + + prop.clear_qubit(1); + assert!(prop.is_identity()); + + prop.track_z(&[2]); + assert_eq!(prop.weight(), 1); + prop.reset(); + assert!(prop.is_identity()); + } +} diff --git a/crates/pecos-simulators/src/gens.rs b/crates/pecos-simulators/src/gens.rs index a53ffbe86..46808a15b 100644 --- a/crates/pecos-simulators/src/gens.rs +++ b/crates/pecos-simulators/src/gens.rs @@ -164,8 +164,9 @@ impl GensHybrid { #[must_use] pub fn generator(&self, i: usize) -> PauliString { assert!(i < self.num_generators(), "generator index out of bounds"); - let phase = self.generator_phase(i); + let mut phase = self.generator_phase(i); let mut paulis = Vec::new(); + let mut num_y_terms = 0usize; for q in 0..self.num_qubits { let has_x = self.row_x[i].contains(q); let has_z = self.row_z[i].contains(q); @@ -173,10 +174,16 @@ impl GensHybrid { (false, false) => continue, (true, false) => Pauli::X, (false, true) => Pauli::Z, - (true, true) => Pauli::Y, + (true, true) => { + num_y_terms += 1; + Pauli::Y + } }; paulis.push((pauli, QubitId::new(q))); } + for _ in 0..num_y_terms { + phase = phase.multiply(&QuarterPhase::MinusI); + } PauliString::with_phase_and_paulis(phase, paulis) } @@ -391,10 +398,11 @@ impl GensGeneric { pub fn generator(&self, i: usize) -> PauliString { assert!(i < self.num_generators(), "generator index out of bounds"); - let phase = self.generator_phase(i); + let mut phase = self.generator_phase(i); // Collect non-identity Paulis let mut paulis = Vec::new(); + let mut num_y_terms = 0usize; // Iterate over all qubits and determine the Pauli at each position for q in 0..self.num_qubits { @@ -405,11 +413,17 @@ impl GensGeneric { (false, false) => continue, // Identity, skip (true, false) => Pauli::X, (false, true) => Pauli::Z, - (true, true) => Pauli::Y, + (true, true) => { + num_y_terms += 1; + Pauli::Y + } }; paulis.push((pauli, QubitId::new(q))); } + for _ in 0..num_y_terms { + phase = phase.multiply(&QuarterPhase::MinusI); + } PauliString::with_phase_and_paulis(phase, paulis) } diff --git a/crates/pecos-simulators/src/lib.rs b/crates/pecos-simulators/src/lib.rs index aad498b58..448e0b3f6 100644 --- a/crates/pecos-simulators/src/lib.rs +++ b/crates/pecos-simulators/src/lib.rs @@ -12,6 +12,7 @@ pub mod arbitrary_rotation_gateable; pub mod batched_ops; +pub mod bitmask_pauli_prop; pub mod circuit_executor; pub mod clifford_frame; pub mod clifford_gateable; @@ -44,6 +45,7 @@ pub mod sparse_stab_y; pub mod stabilizer; pub mod stabilizer_tableau; pub mod stabilizer_test_utils; +pub mod state_access; pub mod state_vec; pub mod state_vec_aos; pub mod state_vec_soa; @@ -57,6 +59,7 @@ pub mod symbolic_sparse_stab_bitset; pub use arbitrary_rotation_gateable::ArbitraryRotationGateable; pub use batched_ops::{BatchedOps, CommandBuffer, RawOps}; +pub use bitmask_pauli_prop::BitmaskPauliProp; pub use circuit_executor::{CircuitExecutor, GateSystem, GateSystemRegistry, execute_batched}; pub use clifford_gateable::{CliffordGateable, MeasurementResult}; pub use coin_toss::CoinToss; @@ -102,6 +105,10 @@ pub use sparse_stab_y::{ }; pub use stabilizer::Stabilizer; pub use stabilizer_tableau::StabilizerTableauSimulator; +pub use state_access::{ + DensityMatrixAccess, PauliExpectationAccess, StabilizerStateVectorConversion, StateAccessError, + StateInfo, StateSampling, StateVectorAccess, random_statevector, +}; // StateVec uses the sparse SoA implementation optimized for QEC workloads. // The dense implementation is available as DenseStateVec / StateVecSoA. pub use state_vec_aos::StateVecAoS; diff --git a/crates/pecos-simulators/src/sparse_stab.rs b/crates/pecos-simulators/src/sparse_stab.rs index 0432793aa..fd67b16e0 100644 --- a/crates/pecos-simulators/src/sparse_stab.rs +++ b/crates/pecos-simulators/src/sparse_stab.rs @@ -301,6 +301,28 @@ where self } + /// Extracts the stabilizer generators as a [`PauliStabilizerGroup`]. + /// + /// Converts the simulator's internal tableau into the algebraic + /// representation, enabling rank analysis, distance calculation, + /// logical operator computation, and other GF(2) operations. + /// + /// [`PauliStabilizerGroup`]: pecos_quantum::PauliStabilizerGroup + #[must_use] + pub fn to_stabilizer_group(&self) -> pecos_quantum::PauliStabilizerGroup { + let generators = self.stabs.generators(); + pecos_quantum::PauliStabilizerGroup::from_generators_unchecked(generators) + } + + /// Extracts the destabilizer generators as a [`PauliSequence`]. + /// + /// [`PauliSequence`]: pecos_quantum::PauliSequence + #[must_use] + pub fn to_destabilizer_sequence(&self) -> pecos_quantum::PauliSequence { + let generators = self.destabs.generators(); + pecos_quantum::PauliSequence::new(generators) + } + /// Returns generator data as sparse index vectors. /// /// Returns `(col_x, col_z, row_x, row_z)` where each is a `Vec>`. diff --git a/crates/pecos-simulators/src/stabilizer.rs b/crates/pecos-simulators/src/stabilizer.rs index b1e1b5bc6..02b7dbb50 100644 --- a/crates/pecos-simulators/src/stabilizer.rs +++ b/crates/pecos-simulators/src/stabilizer.rs @@ -112,6 +112,22 @@ impl Stabilizer { pub fn gens_data(&self, is_stab: bool) -> crate::GensData { self.inner.gens_data(is_stab) } + + /// Extracts the stabilizer generators as a [`PauliStabilizerGroup`]. + /// + /// [`PauliStabilizerGroup`]: pecos_quantum::PauliStabilizerGroup + #[must_use] + pub fn to_stabilizer_group(&self) -> pecos_quantum::PauliStabilizerGroup { + self.inner.to_stabilizer_group() + } + + /// Extracts the destabilizer generators as a [`PauliSequence`]. + /// + /// [`PauliSequence`]: pecos_quantum::PauliSequence + #[must_use] + pub fn to_destabilizer_sequence(&self) -> pecos_quantum::PauliSequence { + self.inner.to_destabilizer_sequence() + } } impl QuantumSimulator for Stabilizer { diff --git a/crates/pecos-simulators/src/state_access.rs b/crates/pecos-simulators/src/state_access.rs new file mode 100644 index 000000000..cde56a329 --- /dev/null +++ b/crates/pecos-simulators/src/state_access.rs @@ -0,0 +1,1342 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Capability traits for inspecting simulator state. +//! +//! These traits deliberately describe what a backend can expose, rather than a +//! single broad "quantum state" interface. A state-vector simulator can provide +//! amplitudes; a density-matrix simulator can provide matrix elements; symbolic +//! propagation backends should not pretend to expose either. + +use crate::clifford_gateable::{CliffordGateable, MeasurementResult}; +use crate::density_matrix::DensityMatrix; +use crate::quantum_simulator::QuantumSimulator; +use crate::sparse_stab::{SparseStabGeneric, SparseStabHybrid}; +use crate::stabilizer::Stabilizer; +use crate::state_vec_aos::StateVecAoS; +use crate::state_vec_soa::StateVecSoA; +use crate::state_vec_soa32::StateVecSoA32; +use crate::state_vec_sparse_aos::SparseStateVecAoS; +use crate::state_vec_sparse_soa::SparseStateVecSoA; +use core::fmt; +use num_complex::Complex64; +use pecos_core::{IndexSet, Pauli, PauliString, Phase, QuarterPhase, QubitId}; +use pecos_quantum::PauliStabilizerGroup; +use pecos_random::{Rng, RngExt as _, SeedableRng}; +use std::error::Error; +use std::f64::consts::TAU; +use std::fmt::Debug; + +/// Error returned by state-inspection capability traits. +#[derive(Clone, Debug, PartialEq, Eq)] +pub enum StateAccessError { + /// `2^num_qubits` cannot be represented as a `usize`. + DimensionOverflow { + /// Number of qubits requested. + num_qubits: usize, + }, + /// A computational-basis index is outside the state Hilbert space. + BasisIndexOutOfRange { + /// Number of qubits in the state. + num_qubits: usize, + /// Hilbert-space dimension, when representable. + dim: usize, + /// Offending basis index. + index: usize, + }, + /// A Pauli string acts outside the state qubit range. + PauliQubitOutOfRange { + /// Number of qubits in the state. + num_qubits: usize, + /// Offending qubit index. + qubit: usize, + }, + /// A sampled/measured qubit is outside the state qubit range. + QubitOutOfRange { + /// Number of qubits in the state. + num_qubits: usize, + /// Offending qubit index. + qubit: usize, + }, + /// A state vector had an unexpected length. + InvalidStateVectorLength { + /// Expected vector length. + expected: usize, + /// Actual vector length. + actual: usize, + }, + /// A density matrix had an unexpected shape. + InvalidDensityMatrixShape { + /// Expected row/column count. + expected: usize, + /// Actual row count. + rows: usize, + /// Actual column count. + cols: usize, + }, + /// Stabilizer generators do not define a unique pure state. + NotPureStabilizerState { + /// Number of qubits in the represented system. + num_qubits: usize, + /// Number of supplied stabilizer generators. + num_generators: usize, + /// Rank of the stabilizer generator span. + rank: usize, + }, +} + +impl fmt::Display for StateAccessError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + Self::DimensionOverflow { num_qubits } => { + write!( + f, + "Hilbert dimension overflows usize for {num_qubits} qubits" + ) + } + Self::BasisIndexOutOfRange { + num_qubits, + dim, + index, + } => write!( + f, + "basis index {index} is outside the {dim}-element Hilbert space for {num_qubits} qubits" + ), + Self::PauliQubitOutOfRange { num_qubits, qubit } => write!( + f, + "Pauli string touches qubit {qubit}, outside {num_qubits}-qubit state" + ), + Self::QubitOutOfRange { num_qubits, qubit } => { + write!(f, "qubit {qubit} is outside {num_qubits}-qubit state") + } + Self::InvalidStateVectorLength { expected, actual } => { + write!( + f, + "invalid state-vector length {actual}; expected {expected}" + ) + } + Self::InvalidDensityMatrixShape { + expected, + rows, + cols, + } => write!( + f, + "invalid density-matrix shape {rows}x{cols}; expected {expected}x{expected}" + ), + Self::NotPureStabilizerState { + num_qubits, + num_generators, + rank, + } => write!( + f, + "stabilizer generators do not define a unique pure state for {num_qubits} qubits: {num_generators} generators, rank {rank}" + ), + } + } +} + +impl Error for StateAccessError {} + +/// Common metadata for state-inspection capabilities. +pub trait StateInfo { + /// Returns the number of qubits represented by the state. + fn num_qubits(&self) -> usize; + + /// Returns the Hilbert-space dimension `2^num_qubits`. + /// + /// # Errors + /// + /// Returns [`StateAccessError::DimensionOverflow`] if the dimension cannot + /// be represented as a `usize`. + fn hilbert_dim(&self) -> Result { + hilbert_dim(self.num_qubits()) + } +} + +impl StateInfo for T +where + T: QuantumSimulator, +{ + fn num_qubits(&self) -> usize { + QuantumSimulator::num_qubits(self) + } +} + +/// Returns a Haar-random pure state vector on `num_qubits` qubits. +/// +/// The vector is sampled by drawing independent complex normal amplitudes and +/// normalizing them. The output is in little-endian computational-basis order, +/// matching PECOS's state-vector backends. +/// +/// # Errors +/// +/// Returns [`StateAccessError::DimensionOverflow`] if `2^num_qubits` does not +/// fit in `usize`. +pub fn random_statevector( + rng: &mut R, + num_qubits: usize, +) -> Result, StateAccessError> +where + R: Rng + ?Sized, +{ + let dim = hilbert_dim(num_qubits)?; + loop { + let mut state: Vec = (0..dim).map(|_| standard_complex_normal(rng)).collect(); + let norm_sqr = state_norm_sqr(&state); + if norm_sqr > f64::EPSILON { + normalize_state_vector(&mut state, norm_sqr); + return Ok(state); + } + } +} + +/// Capability for backends that can expose computational-basis amplitudes. +pub trait StateVectorAccess: StateInfo { + /// Returns one computational-basis amplitude. + /// + /// # Errors + /// + /// Returns an error if `basis_state` is outside the Hilbert space. + fn amplitude(&mut self, basis_state: usize) -> Result; + + /// Returns a dense state vector in little-endian computational-basis order. + /// + /// # Errors + /// + /// Returns an error if the Hilbert-space dimension overflows. + fn state_vector(&mut self) -> Result, StateAccessError>; + + /// Returns the probability of one computational-basis state. + /// + /// # Errors + /// + /// Returns an error if `basis_state` is outside the Hilbert space. + fn basis_probability(&mut self, basis_state: usize) -> Result { + Ok(self.amplitude(basis_state)?.norm_sqr()) + } +} + +/// Capability for backends that can expose a density matrix. +pub trait DensityMatrixAccess: StateInfo { + /// Returns a dense density matrix in little-endian computational-basis order. + /// + /// # Errors + /// + /// Returns an error if the Hilbert-space dimension overflows. + fn density_matrix(&mut self) -> Result>, StateAccessError>; + + /// Returns one density-matrix element. + /// + /// # Errors + /// + /// Returns an error if either index is outside the Hilbert space. + fn density_matrix_element( + &mut self, + row: usize, + col: usize, + ) -> Result { + validate_basis_index(self.num_qubits(), row)?; + validate_basis_index(self.num_qubits(), col)?; + let rho = self.density_matrix()?; + Ok(rho[row][col]) + } + + /// Returns the probability of one computational-basis state. + /// + /// # Errors + /// + /// Returns an error if `basis_state` is outside the Hilbert space. + fn basis_probability(&mut self, basis_state: usize) -> Result { + Ok(self.density_matrix_element(basis_state, basis_state)?.re) + } +} + +/// Capability for backends that can evaluate Pauli expectation values. +pub trait PauliExpectationAccess: StateInfo { + /// Returns `

    ` for the supplied Pauli string. + /// + /// The result is complex so callers can also query phased Pauli strings + /// such as `i X`. For Hermitian Paulis with real phase, the imaginary part + /// should be numerical roundoff only. + /// + /// # Errors + /// + /// Returns an error if the Pauli string acts outside the state. + fn pauli_expectation(&mut self, pauli: &PauliString) -> Result; +} + +/// Capability for backends that can sample projective Pauli-basis measurements. +/// +/// Unlike [`StateVectorAccess`], [`DensityMatrixAccess`], and +/// [`PauliExpectationAccess`], these methods are not passive inspection: +/// sampling mutates the backend by collapsing the measured state and may +/// consume RNG state. +pub trait StateSampling: StateInfo { + /// Samples/measures qubits in the computational (`Z`) basis. + /// + /// Results use the existing PECOS [`MeasurementResult`] convention: + /// `outcome == false` is the `0`/`+Z` outcome and `outcome == true` is + /// the `1`/`-Z` outcome. + /// + /// # Errors + /// + /// Returns an error if any qubit is outside the state. + fn sample_z(&mut self, qubits: &[QubitId]) -> Result, StateAccessError>; + + /// Samples/measures qubits in the `X` basis. + /// + /// # Errors + /// + /// Returns an error if any qubit is outside the state. + fn sample_x(&mut self, qubits: &[QubitId]) -> Result, StateAccessError>; + + /// Samples/measures qubits in the `Y` basis. + /// + /// # Errors + /// + /// Returns an error if any qubit is outside the state. + fn sample_y(&mut self, qubits: &[QubitId]) -> Result, StateAccessError>; +} + +/// Capability for stabilizer backends that can materialize a dense state vector. +/// +/// This is an explicit conversion, not passive inspection. The output has +/// length `2^num_qubits`, so callers should treat it as an exponential-cost +/// debugging and interop path rather than the normal way to query stabilizer +/// states. +pub trait StabilizerStateVectorConversion: StateInfo { + /// Converts the stabilizer state into a dense state vector in little-endian + /// computational-basis order. + /// + /// The returned vector is normalized and has a deterministic global phase: + /// the first nonzero amplitude is real and positive. + /// + /// # Errors + /// + /// Returns an error if the Hilbert-space dimension overflows or if the + /// stabilizer generators do not define a unique pure state. + fn to_state_vector(&self) -> Result, StateAccessError>; +} + +macro_rules! impl_state_sampling { + (impl<$($generic:tt),+> for $ty:ty where $($where_clause:tt)*) => { + impl<$($generic),+> StateSampling for $ty + where + $($where_clause)* + { + fn sample_z( + &mut self, + qubits: &[QubitId], + ) -> Result, StateAccessError> { + sample_z_via_clifford(self, qubits) + } + + fn sample_x( + &mut self, + qubits: &[QubitId], + ) -> Result, StateAccessError> { + sample_x_via_clifford(self, qubits) + } + + fn sample_y( + &mut self, + qubits: &[QubitId], + ) -> Result, StateAccessError> { + sample_y_via_clifford(self, qubits) + } + } + }; + (for $ty:ty) => { + impl StateSampling for $ty { + fn sample_z( + &mut self, + qubits: &[QubitId], + ) -> Result, StateAccessError> { + sample_z_via_clifford(self, qubits) + } + + fn sample_x( + &mut self, + qubits: &[QubitId], + ) -> Result, StateAccessError> { + sample_x_via_clifford(self, qubits) + } + + fn sample_y( + &mut self, + qubits: &[QubitId], + ) -> Result, StateAccessError> { + sample_y_via_clifford(self, qubits) + } + } + }; +} + +impl_state_sampling!(impl for StateVecSoA where R: Rng); +impl_state_sampling!(impl for SparseStateVecSoA where R: Rng + Debug); +impl_state_sampling!(impl for StateVecAoS where R: Rng + SeedableRng + Debug); +impl_state_sampling!(impl for SparseStateVecAoS where R: Rng + Debug); +impl_state_sampling!(impl for StateVecSoA32 where R: Rng); +impl_state_sampling!(impl for DensityMatrix where R: Rng + SeedableRng + Debug + Clone); +impl_state_sampling!(impl for SparseStabGeneric where S: IndexSet, R: Rng + SeedableRng + Debug); +impl_state_sampling!(impl for SparseStabHybrid where R: Rng + SeedableRng + Debug); +impl_state_sampling!(for Stabilizer); + +impl StabilizerStateVectorConversion for SparseStabGeneric +where + S: IndexSet, + R: Rng + SeedableRng + Debug, +{ + fn to_state_vector(&self) -> Result, StateAccessError> { + stabilizer_group_to_state_vector(&self.to_stabilizer_group()) + } +} + +impl StabilizerStateVectorConversion for SparseStabHybrid +where + R: Rng + SeedableRng + Debug, +{ + fn to_state_vector(&self) -> Result, StateAccessError> { + stabilizer_group_to_state_vector(&self.to_stabilizer_group()) + } +} + +impl StabilizerStateVectorConversion for Stabilizer { + fn to_state_vector(&self) -> Result, StateAccessError> { + stabilizer_group_to_state_vector(&self.to_stabilizer_group()) + } +} + +impl StateVectorAccess for StateVecSoA +where + R: Rng, +{ + fn amplitude(&mut self, basis_state: usize) -> Result { + validate_basis_index(StateInfo::num_qubits(self), basis_state)?; + Ok(self.get_amplitude(basis_state)) + } + + fn state_vector(&mut self) -> Result, StateAccessError> { + let expected = self.hilbert_dim()?; + let state = self.state(); + validate_state_vector_len(&state, expected)?; + Ok(state) + } + + fn basis_probability(&mut self, basis_state: usize) -> Result { + validate_basis_index(StateInfo::num_qubits(self), basis_state)?; + Ok(self.probability(basis_state)) + } +} + +impl PauliExpectationAccess for StateVecSoA +where + R: Rng, +{ + fn pauli_expectation(&mut self, pauli: &PauliString) -> Result { + let num_qubits = StateInfo::num_qubits(self); + pauli_expectation_from_state_vector(&self.state_vector()?, num_qubits, pauli) + } +} + +impl StateVectorAccess for SparseStateVecSoA +where + R: Rng + Debug, +{ + fn amplitude(&mut self, basis_state: usize) -> Result { + validate_basis_index(StateInfo::num_qubits(self), basis_state)?; + Ok(self.get_amplitude(basis_state)) + } + + fn state_vector(&mut self) -> Result, StateAccessError> { + let expected = self.hilbert_dim()?; + let state = self.state(); + validate_state_vector_len(&state, expected)?; + Ok(state) + } + + fn basis_probability(&mut self, basis_state: usize) -> Result { + validate_basis_index(StateInfo::num_qubits(self), basis_state)?; + Ok(self.probability(basis_state)) + } +} + +impl PauliExpectationAccess for SparseStateVecSoA +where + R: Rng + Debug, +{ + fn pauli_expectation(&mut self, pauli: &PauliString) -> Result { + let num_qubits = StateInfo::num_qubits(self); + pauli_expectation_from_state_vector(&self.state_vector()?, num_qubits, pauli) + } +} + +impl StateVectorAccess for StateVecAoS +where + R: Rng + SeedableRng + Debug, +{ + fn amplitude(&mut self, basis_state: usize) -> Result { + validate_basis_index(StateInfo::num_qubits(self), basis_state)?; + Ok(self.state()[basis_state]) + } + + fn state_vector(&mut self) -> Result, StateAccessError> { + let expected = self.hilbert_dim()?; + let state = self.state().to_vec(); + validate_state_vector_len(&state, expected)?; + Ok(state) + } + + fn basis_probability(&mut self, basis_state: usize) -> Result { + validate_basis_index(StateInfo::num_qubits(self), basis_state)?; + Ok(self.probability(basis_state)) + } +} + +impl PauliExpectationAccess for StateVecAoS +where + R: Rng + SeedableRng + Debug, +{ + fn pauli_expectation(&mut self, pauli: &PauliString) -> Result { + let num_qubits = StateInfo::num_qubits(self); + pauli_expectation_from_state_vector(&self.state_vector()?, num_qubits, pauli) + } +} + +impl StateVectorAccess for SparseStateVecAoS +where + R: Rng + Debug, +{ + fn amplitude(&mut self, basis_state: usize) -> Result { + validate_basis_index(StateInfo::num_qubits(self), basis_state)?; + Ok(self.get_amplitude(basis_state)) + } + + fn state_vector(&mut self) -> Result, StateAccessError> { + let dim = self.hilbert_dim()?; + let mut state = vec![Complex64::new(0.0, 0.0); dim]; + for (basis_state, amp) in state.iter_mut().enumerate() { + *amp = self.get_amplitude(basis_state); + } + Ok(state) + } +} + +impl PauliExpectationAccess for SparseStateVecAoS +where + R: Rng + Debug, +{ + fn pauli_expectation(&mut self, pauli: &PauliString) -> Result { + let num_qubits = StateInfo::num_qubits(self); + pauli_expectation_from_state_vector(&self.state_vector()?, num_qubits, pauli) + } +} + +impl StateVectorAccess for StateVecSoA32 +where + R: Rng, +{ + fn amplitude(&mut self, basis_state: usize) -> Result { + validate_basis_index(StateInfo::num_qubits(self), basis_state)?; + let amp = self.get_amplitude(basis_state); + Ok(Complex64::new(f64::from(amp.re), f64::from(amp.im))) + } + + fn state_vector(&mut self) -> Result, StateAccessError> { + let expected = self.hilbert_dim()?; + let state: Vec = self + .to_complex_vec() + .into_iter() + .map(|amp| Complex64::new(f64::from(amp.re), f64::from(amp.im))) + .collect(); + validate_state_vector_len(&state, expected)?; + Ok(state) + } + + fn basis_probability(&mut self, basis_state: usize) -> Result { + validate_basis_index(StateInfo::num_qubits(self), basis_state)?; + Ok(self.probability(basis_state)) + } +} + +impl PauliExpectationAccess for StateVecSoA32 +where + R: Rng, +{ + fn pauli_expectation(&mut self, pauli: &PauliString) -> Result { + let num_qubits = StateInfo::num_qubits(self); + pauli_expectation_from_state_vector(&self.state_vector()?, num_qubits, pauli) + } +} + +impl DensityMatrixAccess for DensityMatrix +where + R: Rng + SeedableRng + Debug + Clone, +{ + fn density_matrix(&mut self) -> Result>, StateAccessError> { + let expected = self.hilbert_dim()?; + let rho = self.get_density_matrix(); + validate_density_matrix_shape(&rho, expected)?; + Ok(rho) + } + + fn basis_probability(&mut self, basis_state: usize) -> Result { + validate_basis_index(StateInfo::num_qubits(self), basis_state)?; + Ok(self.probability(basis_state)) + } +} + +impl PauliExpectationAccess for DensityMatrix +where + R: Rng + SeedableRng + Debug + Clone, +{ + fn pauli_expectation(&mut self, pauli: &PauliString) -> Result { + let num_qubits = StateInfo::num_qubits(self); + pauli_expectation_from_density_matrix(&self.density_matrix()?, num_qubits, pauli) + } +} + +impl PauliExpectationAccess for SparseStabGeneric +where + S: IndexSet, + R: Rng + SeedableRng + Debug, +{ + fn pauli_expectation(&mut self, pauli: &PauliString) -> Result { + pauli_expectation_from_stabilizer_group( + &self.to_stabilizer_group(), + StateInfo::num_qubits(self), + pauli, + ) + } +} + +impl PauliExpectationAccess for SparseStabHybrid +where + R: Rng + SeedableRng + Debug, +{ + fn pauli_expectation(&mut self, pauli: &PauliString) -> Result { + pauli_expectation_from_stabilizer_group( + &self.to_stabilizer_group(), + StateInfo::num_qubits(self), + pauli, + ) + } +} + +impl PauliExpectationAccess for Stabilizer { + fn pauli_expectation(&mut self, pauli: &PauliString) -> Result { + pauli_expectation_from_stabilizer_group( + &self.to_stabilizer_group(), + StateInfo::num_qubits(self), + pauli, + ) + } +} + +fn hilbert_dim(num_qubits: usize) -> Result { + let shift = u32::try_from(num_qubits) + .map_err(|_| StateAccessError::DimensionOverflow { num_qubits })?; + if shift >= usize::BITS { + return Err(StateAccessError::DimensionOverflow { num_qubits }); + } + Ok(1usize << shift) +} + +fn validate_basis_index(num_qubits: usize, index: usize) -> Result { + let dim = hilbert_dim(num_qubits)?; + if index >= dim { + return Err(StateAccessError::BasisIndexOutOfRange { + num_qubits, + dim, + index, + }); + } + Ok(dim) +} + +fn validate_pauli_support(num_qubits: usize, pauli: &PauliString) -> Result<(), StateAccessError> { + for qubit in pauli.qubits() { + if qubit >= num_qubits { + return Err(StateAccessError::PauliQubitOutOfRange { num_qubits, qubit }); + } + } + Ok(()) +} + +fn validate_qubit_support(num_qubits: usize, qubits: &[QubitId]) -> Result<(), StateAccessError> { + for qubit in qubits { + let q = qubit.index(); + if q >= num_qubits { + return Err(StateAccessError::QubitOutOfRange { + num_qubits, + qubit: q, + }); + } + } + Ok(()) +} + +fn validate_state_vector_len(state: &[Complex64], expected: usize) -> Result<(), StateAccessError> { + if state.len() != expected { + return Err(StateAccessError::InvalidStateVectorLength { + expected, + actual: state.len(), + }); + } + Ok(()) +} + +fn validate_density_matrix_shape( + rho: &[Vec], + expected: usize, +) -> Result<(), StateAccessError> { + if rho.len() != expected { + return Err(StateAccessError::InvalidDensityMatrixShape { + expected, + rows: rho.len(), + cols: rho.first().map_or(0, Vec::len), + }); + } + for row in rho { + if row.len() != expected { + return Err(StateAccessError::InvalidDensityMatrixShape { + expected, + rows: rho.len(), + cols: row.len(), + }); + } + } + Ok(()) +} + +fn sample_z_via_clifford( + backend: &mut T, + qubits: &[QubitId], +) -> Result, StateAccessError> +where + T: CliffordGateable + StateInfo, +{ + validate_qubit_support(StateInfo::num_qubits(backend), qubits)?; + Ok(backend.mz(qubits)) +} + +fn sample_x_via_clifford( + backend: &mut T, + qubits: &[QubitId], +) -> Result, StateAccessError> +where + T: CliffordGateable + StateInfo, +{ + validate_qubit_support(StateInfo::num_qubits(backend), qubits)?; + Ok(backend.mx(qubits)) +} + +fn sample_y_via_clifford( + backend: &mut T, + qubits: &[QubitId], +) -> Result, StateAccessError> +where + T: CliffordGateable + StateInfo, +{ + validate_qubit_support(StateInfo::num_qubits(backend), qubits)?; + Ok(backend.my(qubits)) +} + +fn stabilizer_group_to_state_vector( + group: &PauliStabilizerGroup, +) -> Result, StateAccessError> { + let num_qubits = group.num_qubits(); + let num_generators = group.num_generators(); + let rank = group.rank(); + if rank != num_qubits { + return Err(StateAccessError::NotPureStabilizerState { + num_qubits, + num_generators, + rank, + }); + } + + let dim = hilbert_dim(num_qubits)?; + let generators = group.stabilizers(); + for seed in 0..dim { + let mut state = vec![Complex64::new(0.0, 0.0); dim]; + state[seed] = Complex64::new(1.0, 0.0); + + for generator in generators { + validate_pauli_support(num_qubits, generator)?; + apply_stabilizer_projector(&mut state, generator); + if state_norm_sqr(&state) <= f64::EPSILON { + break; + } + } + + let norm_sqr = state_norm_sqr(&state); + if norm_sqr > f64::EPSILON { + normalize_state_vector(&mut state, norm_sqr); + canonicalize_global_phase(&mut state); + return Ok(state); + } + } + + Err(StateAccessError::NotPureStabilizerState { + num_qubits, + num_generators, + rank, + }) +} + +fn apply_stabilizer_projector(state: &mut [Complex64], generator: &PauliString) { + let input = state.to_vec(); + state.fill(Complex64::new(0.0, 0.0)); + for (basis_state, amplitude) in input.iter().copied().enumerate() { + state[basis_state] += amplitude * 0.5; + if amplitude.norm_sqr() == 0.0 { + continue; + } + let (output_state, coefficient) = pauli_action_on_basis_index(generator, basis_state); + state[output_state] += coefficient * amplitude * 0.5; + } +} + +fn state_norm_sqr(state: &[Complex64]) -> f64 { + state.iter().map(Complex64::norm_sqr).sum() +} + +fn standard_complex_normal(rng: &mut R) -> Complex64 +where + R: Rng + ?Sized, +{ + Complex64::new(standard_normal(rng), standard_normal(rng)) +} + +fn standard_normal(rng: &mut R) -> f64 +where + R: Rng + ?Sized, +{ + loop { + let u1 = rng.random::(); + if u1 > 0.0 { + let u2 = rng.random::(); + return (-2.0 * u1.ln()).sqrt() * (TAU * u2).cos(); + } + } +} + +fn normalize_state_vector(state: &mut [Complex64], norm_sqr: f64) { + let scale = norm_sqr.sqrt(); + for amplitude in state { + *amplitude /= scale; + } +} + +fn canonicalize_global_phase(state: &mut [Complex64]) { + let Some(first_nonzero) = state + .iter() + .copied() + .find(|amplitude| amplitude.norm_sqr() > f64::EPSILON) + else { + return; + }; + let phase = first_nonzero / Complex64::new(first_nonzero.norm(), 0.0); + let correction = phase.conj(); + for amplitude in state { + *amplitude *= correction; + } +} + +fn pauli_action_on_basis_index(pauli: &PauliString, basis_state: usize) -> (usize, Complex64) { + let mut output = basis_state; + let mut coefficient = pauli.phase().to_complex(); + for (single, qubit) in pauli.iter_pairs() { + let q = qubit.index(); + let bit = (basis_state >> q) & 1; + match single { + Pauli::I => {} + Pauli::X => { + output ^= 1usize << q; + } + Pauli::Y => { + output ^= 1usize << q; + coefficient *= if bit == 0 { + Complex64::new(0.0, 1.0) + } else { + Complex64::new(0.0, -1.0) + }; + } + Pauli::Z => { + if bit == 1 { + coefficient = -coefficient; + } + } + } + } + (output, coefficient) +} + +fn pauli_expectation_from_state_vector( + state: &[Complex64], + num_qubits: usize, + pauli: &PauliString, +) -> Result { + validate_pauli_support(num_qubits, pauli)?; + let dim = hilbert_dim(num_qubits)?; + validate_state_vector_len(state, dim)?; + let mut expectation = Complex64::new(0.0, 0.0); + for basis_state in 0..dim { + let (output, coefficient) = pauli_action_on_basis_index(pauli, basis_state); + expectation += coefficient * state[basis_state] * state[output].conj(); + } + Ok(expectation) +} + +fn pauli_expectation_from_density_matrix( + rho: &[Vec], + num_qubits: usize, + pauli: &PauliString, +) -> Result { + validate_pauli_support(num_qubits, pauli)?; + let dim = hilbert_dim(num_qubits)?; + validate_density_matrix_shape(rho, dim)?; + let mut expectation = Complex64::new(0.0, 0.0); + for (basis_state, rho_row) in rho.iter().enumerate().take(dim) { + let (output, coefficient) = pauli_action_on_basis_index(pauli, basis_state); + expectation += coefficient * rho_row[output]; + } + Ok(expectation) +} + +fn pauli_expectation_from_stabilizer_group( + stabilizers: &PauliStabilizerGroup, + num_qubits: usize, + pauli: &PauliString, +) -> Result { + validate_pauli_support(num_qubits, pauli)?; + + let mut positive_body = pauli.clone(); + positive_body.set_phase(QuarterPhase::PlusOne); + if !stabilizers.contains(&positive_body) { + return Ok(Complex64::new(0.0, 0.0)); + } + + let stabilizer_phase = if stabilizers.contains_with_phase(&positive_body) { + QuarterPhase::PlusOne + } else { + QuarterPhase::MinusOne + }; + Ok(pauli + .phase() + .multiply(&stabilizer_phase.conjugate()) + .to_complex()) +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::{CliffordGateable, SparseStab, SparseStabHybrid, Stabilizer, StateVec, qid}; + use pecos_core::QubitId; + use pecos_core::pauli::algebra::i; + use pecos_core::pauli::*; + use pecos_random::PecosRng; + + fn assert_close(actual: Complex64, expected: Complex64) { + assert!( + (actual - expected).norm() < 1e-10, + "actual={actual}, expected={expected}" + ); + } + + fn assert_state_vectors_close(actual: &[Complex64], expected: &[Complex64]) { + assert_eq!(actual.len(), expected.len()); + for (index, (&actual_amp, &expected_amp)) in actual.iter().zip(expected).enumerate() { + assert!( + (actual_amp - expected_amp).norm() < 1e-10, + "state-vector mismatch at basis {index}: actual={actual_amp}, expected={expected_amp}" + ); + } + } + + #[test] + fn state_vector_access_flushes_pending_gates() { + let mut state = StateVecSoA::new(1); + state.h(&qid(0)); + + let amp0 = StateVectorAccess::amplitude(&mut state, 0).unwrap(); + let amp1 = StateVectorAccess::amplitude(&mut state, 1).unwrap(); + let expected = 1.0 / 2.0_f64.sqrt(); + assert_close(amp0, Complex64::new(expected, 0.0)); + assert_close(amp1, Complex64::new(expected, 0.0)); + assert!((StateVectorAccess::basis_probability(&mut state, 0).unwrap() - 0.5).abs() < 1e-10); + } + + #[test] + fn random_statevector_is_normalized_and_seed_reproducible() { + let mut rng = PecosRng::seed_from_u64(123); + let state = random_statevector(&mut rng, 3).unwrap(); + assert_eq!(state.len(), 8); + assert!((state_norm_sqr(&state) - 1.0).abs() < 1e-12); + + let mut same_seed = PecosRng::seed_from_u64(123); + let same = random_statevector(&mut same_seed, 3).unwrap(); + assert_eq!(state, same); + + let mut different_seed = PecosRng::seed_from_u64(456); + let different = random_statevector(&mut different_seed, 3).unwrap(); + assert_ne!(state, different); + } + + #[test] + fn random_statevector_haar_marginal_is_reasonable() { + let mut rng = PecosRng::seed_from_u64(123); + let samples = 2_000; + let mut p0_sum = 0.0; + for _ in 0..samples { + let state = random_statevector(&mut rng, 2).unwrap(); + p0_sum += state[0].norm_sqr(); + } + let mean = p0_sum / samples as f64; + assert!( + (0.22..0.28).contains(&mean), + "expected E[|psi_0|^2] near 1/4 for a 4D Haar state, got {mean}" + ); + } + + #[test] + fn sparse_state_vector_access_returns_dense_vector() { + let mut state = StateVec::new(2); + state.x(&qid(1)); + + let dense = state.state_vector().unwrap(); + assert_eq!(dense.len(), 4); + assert_close(dense[0], Complex64::new(0.0, 0.0)); + assert_close(dense[2], Complex64::new(1.0, 0.0)); + } + + #[test] + fn all_state_vector_backends_expose_amplitudes() { + let mut dense_soa = StateVecSoA::new(1); + let mut dense_aos = StateVecAoS::new(1); + let mut sparse_soa = SparseStateVecSoA::new(1); + let mut sparse_aos = SparseStateVecAoS::new(1); + let mut soa32 = StateVecSoA32::new(1); + + dense_soa.x(&qid(0)); + dense_aos.x(&qid(0)); + sparse_soa.x(&qid(0)); + sparse_aos.x(&qid(0)); + soa32.x(&qid(0)); + + assert_close(dense_soa.amplitude(1).unwrap(), Complex64::new(1.0, 0.0)); + assert_close(dense_aos.amplitude(1).unwrap(), Complex64::new(1.0, 0.0)); + assert_close(sparse_soa.amplitude(1).unwrap(), Complex64::new(1.0, 0.0)); + assert_close(sparse_aos.amplitude(1).unwrap(), Complex64::new(1.0, 0.0)); + assert_close(soa32.amplitude(1).unwrap(), Complex64::new(1.0, 0.0)); + } + + #[test] + fn state_vector_pauli_expectations_match_known_states() { + let mut plus = StateVec::new(1); + plus.h(&qid(0)); + + assert_close( + plus.pauli_expectation(&X(0)).unwrap(), + Complex64::new(1.0, 0.0), + ); + assert_close( + plus.pauli_expectation(&Z(0)).unwrap(), + Complex64::new(0.0, 0.0), + ); + assert_close( + plus.pauli_expectation(&(i * X(0))).unwrap(), + Complex64::new(0.0, 1.0), + ); + } + + #[test] + fn density_matrix_access_and_expectation_match_known_state() { + let mut state = DensityMatrix::new(1); + state.h(&qid(0)); + + let rho = state.density_matrix().unwrap(); + assert_eq!(rho.len(), 2); + assert_close(rho[0][0], Complex64::new(0.5, 0.0)); + assert_close(rho[0][1], Complex64::new(0.5, 0.0)); + assert!( + (DensityMatrixAccess::basis_probability(&mut state, 0).unwrap() - 0.5).abs() < 1e-10 + ); + assert_close( + state.pauli_expectation(&X(0)).unwrap(), + Complex64::new(1.0, 0.0), + ); + assert_close( + state.pauli_expectation(&Z(0)).unwrap(), + Complex64::new(0.0, 0.0), + ); + } + + #[test] + fn sparse_stab_pauli_expectation_uses_signed_stabilizer_membership() { + let mut one = SparseStab::new(1); + one.x(&qid(0)); + + assert_close( + one.pauli_expectation(&Z(0)).unwrap(), + Complex64::new(-1.0, 0.0), + ); + assert_close( + one.pauli_expectation(&(-Z(0))).unwrap(), + Complex64::new(1.0, 0.0), + ); + assert_close( + one.pauli_expectation(&(i * Z(0))).unwrap(), + Complex64::new(0.0, -1.0), + ); + assert_close( + one.pauli_expectation(&X(0)).unwrap(), + Complex64::new(0.0, 0.0), + ); + } + + #[test] + fn sparse_stab_pauli_expectation_matches_state_vector_for_bell_state() { + let mut state_vec = StateVec::new(2); + let mut stab = SparseStab::new(2); + state_vec.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); + stab.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); + + for pauli in [X(0) & X(1), Y(0) & Y(1), Z(0) & Z(1), X(0), Z(0)] { + let expected = state_vec.pauli_expectation(&pauli).unwrap(); + let actual = stab.pauli_expectation(&pauli).unwrap(); + assert_close(actual, expected); + } + } + + #[test] + fn sparse_stab_hybrid_supports_pauli_expectation_access() { + let mut plus = SparseStabHybrid::new(1); + plus.h(&qid(0)); + + assert_close( + plus.pauli_expectation(&X(0)).unwrap(), + Complex64::new(1.0, 0.0), + ); + assert_close( + plus.pauli_expectation(&Z(0)).unwrap(), + Complex64::new(0.0, 0.0), + ); + assert_close( + plus.pauli_expectation(&(i * X(0))).unwrap(), + Complex64::new(0.0, 1.0), + ); + } + + #[test] + fn stabilizer_generator_bridge_preserves_y_phase_convention() { + let mut sparse = SparseStab::new(1); + sparse.h(&qid(0)).sz(&qid(0)); + + assert_close( + sparse.pauli_expectation(&Y(0)).unwrap(), + Complex64::new(1.0, 0.0), + ); + assert_close( + sparse.pauli_expectation(&X(0)).unwrap(), + Complex64::new(0.0, 0.0), + ); + + let mut hybrid = SparseStabHybrid::new(1); + hybrid.h(&qid(0)).sz(&qid(0)); + assert_close( + hybrid.pauli_expectation(&Y(0)).unwrap(), + Complex64::new(1.0, 0.0), + ); + } + + #[test] + fn default_stabilizer_supports_pauli_expectation_access() { + let mut bell = Stabilizer::new(2); + bell.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); + + assert_close( + bell.pauli_expectation(&(X(0) & X(1))).unwrap(), + Complex64::new(1.0, 0.0), + ); + assert_close( + bell.pauli_expectation(&(Z(0) & Z(1))).unwrap(), + Complex64::new(1.0, 0.0), + ); + assert_close( + bell.pauli_expectation(&Z(0)).unwrap(), + Complex64::new(0.0, 0.0), + ); + } + + #[test] + fn state_sampling_z_collapses_state_vector() { + let mut state = StateVec::new(1); + state.h(&qid(0)); + + let first = state.sample_z(&qid(0)).unwrap(); + assert_eq!(first.len(), 1); + assert!(!first[0].is_deterministic); + + let second = state.sample_z(&qid(0)).unwrap(); + assert_eq!(second.len(), 1); + assert!(second[0].is_deterministic); + assert_eq!(second[0].outcome, first[0].outcome); + } + + #[test] + fn state_sampling_x_and_y_bases_use_existing_measurement_semantics() { + let mut plus = StateVec::new(1); + plus.h(&qid(0)); + let x_result = plus.sample_x(&qid(0)).unwrap(); + assert!(x_result[0].is_deterministic); + assert!(!x_result[0].outcome); + + let mut plus_i = StateVec::new(1); + plus_i.h(&qid(0)).sz(&qid(0)); + let y_result = plus_i.sample_y(&qid(0)).unwrap(); + assert!(y_result[0].is_deterministic); + assert!(!y_result[0].outcome); + } + + #[test] + fn state_sampling_batch_preserves_requested_qubit_order() { + let mut state = StateVec::new(2); + state.x(&qid(0)); + + let results = state.sample_z(&[QubitId(1), QubitId(0)]).unwrap(); + assert_eq!(results.len(), 2); + assert!(results[0].is_deterministic); + assert!(results[1].is_deterministic); + assert!(!results[0].outcome); + assert!(results[1].outcome); + } + + #[test] + fn state_sampling_is_available_on_density_matrix_and_stabilizers() { + let mut density = DensityMatrix::new(1); + density.x(&qid(0)); + let density_result = density.sample_z(&qid(0)).unwrap(); + assert!(density_result[0].is_deterministic); + assert!(density_result[0].outcome); + + let mut sparse = SparseStab::new(1); + sparse.x(&qid(0)); + let sparse_result = sparse.sample_z(&qid(0)).unwrap(); + assert!(sparse_result[0].is_deterministic); + assert!(sparse_result[0].outcome); + + let mut hybrid = SparseStabHybrid::new(1); + hybrid.x(&qid(0)); + let hybrid_result = hybrid.sample_z(&qid(0)).unwrap(); + assert!(hybrid_result[0].is_deterministic); + assert!(hybrid_result[0].outcome); + + let mut default_stabilizer = Stabilizer::new(1); + default_stabilizer.x(&qid(0)); + let default_result = default_stabilizer.sample_z(&qid(0)).unwrap(); + assert!(default_result[0].is_deterministic); + assert!(default_result[0].outcome); + } + + #[test] + fn state_access_rejects_out_of_range_queries() { + let mut state = StateVec::new(1); + assert!(matches!( + state.amplitude(2).unwrap_err(), + StateAccessError::BasisIndexOutOfRange { .. } + )); + assert!(matches!( + state.pauli_expectation(&X(1)).unwrap_err(), + StateAccessError::PauliQubitOutOfRange { .. } + )); + let sample_result = state.sample_z(&[QubitId(1)]); + assert!(matches!( + sample_result, + Err(StateAccessError::QubitOutOfRange { .. }) + )); + + let mut rho = DensityMatrix::new(1); + assert!(matches!( + rho.density_matrix_element(0, 2).unwrap_err(), + StateAccessError::BasisIndexOutOfRange { .. } + )); + } + + #[test] + fn sparse_stabilizer_to_state_vector_matches_initial_state() { + let sparse = SparseStab::new(2); + let dense = sparse.to_state_vector().unwrap(); + + assert_state_vectors_close( + &dense, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + ], + ); + } + + #[test] + fn sparse_stabilizer_to_state_vector_preserves_signed_basis_state() { + let mut sparse = SparseStab::new(1); + sparse.x(&qid(0)); + + let dense = sparse.to_state_vector().unwrap(); + assert_state_vectors_close( + &dense, + &[Complex64::new(0.0, 0.0), Complex64::new(1.0, 0.0)], + ); + } + + #[test] + fn sparse_stabilizer_to_state_vector_matches_bell_statevec() { + let mut sparse = SparseStab::new(2); + sparse.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); + + let mut state_vec = StateVec::new(2); + state_vec.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); + + let dense = sparse.to_state_vector().unwrap(); + assert_state_vectors_close(&dense, &state_vec.state_vector().unwrap()); + } + + #[test] + fn sparse_stabilizer_to_state_vector_preserves_complex_phase_state() { + let mut sparse = SparseStab::new(1); + sparse.h(&qid(0)).sz(&qid(0)); + + let mut state_vec = StateVec::new(1); + state_vec.h(&qid(0)).sz(&qid(0)); + + let dense = sparse.to_state_vector().unwrap(); + assert_state_vectors_close(&dense, &state_vec.state_vector().unwrap()); + } + + #[test] + fn stabilizer_to_state_vector_is_available_on_hybrid_and_default_wrapper() { + let mut hybrid = SparseStabHybrid::new(2); + hybrid.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); + + let mut default_stabilizer = Stabilizer::new(2); + default_stabilizer + .h(&qid(0)) + .cx(&[(QubitId(0), QubitId(1))]); + + let hybrid_dense = hybrid.to_state_vector().unwrap(); + let default_dense = default_stabilizer.to_state_vector().unwrap(); + assert_state_vectors_close(&hybrid_dense, &default_dense); + } +} diff --git a/exp/pecos-lindblad/Cargo.toml b/exp/pecos-lindblad/Cargo.toml index 58d384e14..683ed1cca 100644 --- a/exp/pecos-lindblad/Cargo.toml +++ b/exp/pecos-lindblad/Cargo.toml @@ -20,6 +20,7 @@ serde = ["dep:serde"] [dependencies] num-complex.workspace = true +pecos-quantum.workspace = true thiserror.workspace = true rand.workspace = true serde = { workspace = true, optional = true } @@ -27,7 +28,6 @@ serde = { workspace = true, optional = true } [dev-dependencies] approx = "0.5" pecos-qec.workspace = true -pecos-quantum.workspace = true proptest = "1.4" rand.workspace = true serde_json.workspace = true diff --git a/exp/pecos-lindblad/src/basis.rs b/exp/pecos-lindblad/src/basis.rs index 5bc4f3059..7a6f94458 100644 --- a/exp/pecos-lindblad/src/basis.rs +++ b/exp/pecos-lindblad/src/basis.rs @@ -13,6 +13,7 @@ //! Pauli basis types for Lindblad -> Pauli-Lindblad synthesis. use std::fmt; +use std::str::FromStr; /// Single-qubit Pauli operator. #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)] @@ -76,12 +77,25 @@ impl Pauli1 { #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))] pub struct PauliString(pub Vec); +#[derive(Clone, Copy, Debug, PartialEq, Eq)] +pub struct ParsePauliStringError { + invalid_char: char, +} + +impl fmt::Display for ParsePauliStringError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "invalid Pauli character {:?}", self.invalid_char) + } +} + +impl std::error::Error for ParsePauliStringError {} + impl PauliString { pub fn single(p: Pauli1) -> Self { PauliString(vec![p]) } - pub fn from_str(s: &str) -> Option { + pub fn from_label(s: &str) -> Option { s.chars() .map(Pauli1::from_char) .collect::>>() @@ -154,6 +168,21 @@ impl PauliString { } } +impl FromStr for PauliString { + type Err = ParsePauliStringError; + + fn from_str(s: &str) -> Result { + let mut paulis = Vec::with_capacity(s.len()); + for c in s.chars() { + let Some(pauli) = Pauli1::from_char(c) else { + return Err(ParsePauliStringError { invalid_char: c }); + }; + paulis.push(pauli); + } + Ok(PauliString(paulis)) + } +} + impl fmt::Display for PauliString { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { for p in &self.0 { @@ -169,7 +198,7 @@ mod tests { #[test] fn roundtrip_string() { - let s = PauliString::from_str("XYZ").unwrap(); + let s = PauliString::from_label("XYZ").unwrap(); assert_eq!(s.num_qubits(), 3); assert_eq!(s.weight(), 3); assert_eq!(format!("{}", s), "XYZ"); @@ -177,21 +206,21 @@ mod tests { #[test] fn identity_weight() { - let s = PauliString::from_str("III").unwrap(); + let s = PauliString::from_label("III").unwrap(); assert_eq!(s.weight(), 0); } #[test] fn mixed_weight() { - let s = PauliString::from_str("IXI").unwrap(); + let s = PauliString::from_label("IXI").unwrap(); assert_eq!(s.weight(), 1); } #[test] fn symplectic_product_2q() { - let ix = PauliString::from_str("IX").unwrap(); - let iz = PauliString::from_str("IZ").unwrap(); - let zx = PauliString::from_str("ZX").unwrap(); + let ix = PauliString::from_label("IX").unwrap(); + let iz = PauliString::from_label("IZ").unwrap(); + let zx = PauliString::from_label("ZX").unwrap(); assert_eq!(ix.symplectic_product(&iz), 1); // X,Z anticommute on right assert_eq!(ix.symplectic_product(&ix), 0); assert_eq!(zx.symplectic_product(&iz), 1); // X,Z on right anticommute @@ -202,9 +231,9 @@ mod tests { fn enumerate_1q_gives_xyz() { let all = PauliString::enumerate_nonidentity(1); assert_eq!(all.len(), 3); - assert_eq!(all[0], PauliString::from_str("X").unwrap()); - assert_eq!(all[1], PauliString::from_str("Y").unwrap()); - assert_eq!(all[2], PauliString::from_str("Z").unwrap()); + assert_eq!(all[0], PauliString::from_label("X").unwrap()); + assert_eq!(all[1], PauliString::from_label("Y").unwrap()); + assert_eq!(all[2], PauliString::from_label("Z").unwrap()); } #[test] @@ -212,8 +241,8 @@ mod tests { let all = PauliString::enumerate_nonidentity(2); assert_eq!(all.len(), 15); // First should be IX (idx 1 = 0b01 = 0|X). - assert_eq!(all[0], PauliString::from_str("IX").unwrap()); + assert_eq!(all[0], PauliString::from_label("IX").unwrap()); // Last should be ZZ (idx 15 = 0b1111 = Z|Z). - assert_eq!(all[14], PauliString::from_str("ZZ").unwrap()); + assert_eq!(all[14], PauliString::from_label("ZZ").unwrap()); } } diff --git a/exp/pecos-lindblad/src/noise_models.rs b/exp/pecos-lindblad/src/noise_models.rs index 882f16151..33202bade 100644 --- a/exp/pecos-lindblad/src/noise_models.rs +++ b/exp/pecos-lindblad/src/noise_models.rs @@ -193,7 +193,7 @@ pub fn recover_ad_pd_2q_from_cz_theta( if omega_cz <= 0.0 || theta <= 0.0 { return None; } - let r = |s: &str| model.rate(&PauliString::from_str(s).unwrap()); + let r = |s: &str| model.rate(&PauliString::from_label(s).unwrap()); let factor_weight1_amp = (2.0 * theta + (2.0 * theta).sin()) / 16.0; // Amplitude damping: average the two equal rates (paper's 2-fold degeneracy). @@ -257,7 +257,7 @@ pub fn recover_ad_pd_2q_from_cx_theta( // Degenerate: can't separate beta_down_r from beta_phi_r. return None; } - let r = |s: &str| model.rate(&PauliString::from_str(s).unwrap()); + let r = |s: &str| model.rate(&PauliString::from_label(s).unwrap()); // Left qubit: clean single-parameter back-solves. let factor_weight1_amp_l = (2.0 * theta + s2) / 16.0; @@ -296,7 +296,7 @@ pub fn recover_ad_pd_2q_from_cx_theta( /// residuals flag model mismatch (noise source beyond AD+PD). pub fn cz_recovery_residual(model: &crate::PauliLindbladModel) -> f64 { use crate::PauliString; - let r = |s: &str| model.rate(&PauliString::from_str(s).unwrap()); + let r = |s: &str| model.rate(&PauliString::from_label(s).unwrap()); let pairs = [ (r("IX"), r("IY")), (r("XI"), r("YI")), diff --git a/exp/pecos-lindblad/src/pauli_lindblad.rs b/exp/pecos-lindblad/src/pauli_lindblad.rs index a0fdec0dc..f103a1c37 100644 --- a/exp/pecos-lindblad/src/pauli_lindblad.rs +++ b/exp/pecos-lindblad/src/pauli_lindblad.rs @@ -12,6 +12,9 @@ //! Sparse Pauli-Lindblad noise model (arXiv:2201.09866 generator form). +use std::collections::BTreeMap; + +use pecos_quantum::{ChannelError, DiagonalPtm, basis_bitmask, basis_label}; use rand::{Rng, RngExt}; use crate::basis::{Pauli1, PauliString}; @@ -56,6 +59,65 @@ impl PauliLindbladModel { self.rates.iter().sum() } + /// Number of qubits spanned by this model. + #[must_use] + pub fn num_qubits(&self) -> usize { + self.supports + .iter() + .map(PauliString::num_qubits) + .max() + .unwrap_or(0) + } + + /// Converts the Pauli-Lindblad model to diagonal PTM fidelities. + /// + /// For `N(rho) = exp(sum_k lambda_k (P_k rho P_k - rho))`, a Pauli basis + /// element `B` has diagonal PTM entry + /// `exp(-2 * sum_{k: {P_k, B}=0} lambda_k)`. + /// + /// # Errors + /// + /// Returns an error when supports have inconsistent qubit counts or the + /// PECOS Pauli-basis dimension cannot be represented. + pub fn to_diagonal_ptm(&self) -> Result { + let n = self.num_qubits(); + for support in &self.supports { + if support.num_qubits() != n { + return Err(ChannelError::UnsupportedChannelExpr { + reason: format!( + "PauliLindbladModel support {} has {} qubits in a {}-qubit model", + support, + support.num_qubits(), + n + ), + }); + } + } + + let basis_len = pecos_quantum::pauli_basis_len(n)?; + let mut fidelities = BTreeMap::new(); + for basis_idx in 0..basis_len { + let label = basis_label(n, basis_idx)?; + let basis_pauli = PauliString::from_label(&label).ok_or_else(|| { + ChannelError::UnsupportedChannelExpr { + reason: format!("internal basis label {label} was not a Lindblad Pauli string"), + } + })?; + let anticommuting_rate: f64 = self + .supports + .iter() + .zip(&self.rates) + .filter(|(support, _)| support.symplectic_product(&basis_pauli) == 1) + .map(|(_, rate)| *rate) + .sum(); + fidelities.insert( + basis_bitmask(n, basis_idx)?, + (-2.0 * anticommuting_rate).exp(), + ); + } + DiagonalPtm::try_new(n, fidelities) + } + /// Sum of rates restricted to a given Pauli weight (number of /// non-identity factors). pub fn rate_at_weight(&self, weight: usize) -> f64 { @@ -104,7 +166,7 @@ impl PauliLindbladModel { ]; let mut out = [0.0; 15]; for (i, label) in ORDER.iter().enumerate() { - out[i] = self.rate(&PauliString::from_str(label).unwrap()); + out[i] = self.rate(&PauliString::from_label(label).unwrap()); } out } @@ -275,12 +337,12 @@ impl PauliLindbladModel { match weight { 1 => msgs.push(format!( "weight-1 residual {:.3e}: suggests missing incoherent single-qubit noise \ - (T_1, T_phi mis-characterized, or extra dephasing/relaxation channels)", + (T_1, T_phi mischaracterized, or extra dephasing/relaxation channels)", total_abs )), 2 => msgs.push(format!( "weight-2 residual {:.3e}: suggests correlated 2-qubit noise not in model \ - (coherent ZZ crosstalk, leakage-induced correlations, or gate mis-calibration)", + (coherent ZZ crosstalk, leakage-induced correlations, or gate miscalibration)", total_abs )), w if *w >= 3 => msgs.push(format!( @@ -292,13 +354,13 @@ impl PauliLindbladModel { } } // Highlight the single worst Pauli as a concrete pointer. - if let Some((p, r)) = self.max_residual(other) { - if r.abs() >= tol { - msgs.push(format!( - "largest per-Pauli residual: |lambda_{{{}}}^pred - lambda_{{{}}}^meas| = {:.3e}", - p, p, r - )); - } + if let Some((p, r)) = self.max_residual(other) + && r.abs() >= tol + { + msgs.push(format!( + "largest per-Pauli residual: |lambda_{{{}}}^pred - lambda_{{{}}}^meas| = {:.3e}", + p, p, r + )); } msgs } @@ -329,9 +391,9 @@ mod tests { #[test] fn summary_helpers() { let supports = vec![ - PauliString::from_str("IX").unwrap(), - PauliString::from_str("IZ").unwrap(), - PauliString::from_str("XX").unwrap(), + PauliString::from_label("IX").unwrap(), + PauliString::from_label("IZ").unwrap(), + PauliString::from_label("XX").unwrap(), ]; let rates = vec![0.001, 0.003, 0.002]; let model = PauliLindbladModel::new(supports, rates); @@ -357,4 +419,29 @@ mod tests { assert_eq!(s, PauliString::single(Pauli1::I)); } } + + #[test] + fn diagonal_ptm_matches_pauli_lindblad_rates() { + let model = PauliLindbladModel::new( + vec![ + PauliString::single(Pauli1::X), + PauliString::single(Pauli1::Z), + ], + vec![0.2, 0.3], + ); + + let diagonal = model.to_diagonal_ptm().unwrap(); + let label = |s: &str| { + let idx = ["I", "X", "Y", "Z"] + .iter() + .position(|label| *label == s) + .unwrap(); + pecos_quantum::basis_bitmask(1, idx).unwrap() + }; + + assert!((diagonal.fidelity(&label("I")) - 1.0).abs() < 1e-12); + assert!((diagonal.fidelity(&label("X")) - (-0.6_f64).exp()).abs() < 1e-12); + assert!((diagonal.fidelity(&label("Y")) - (-1.0_f64).exp()).abs() < 1e-12); + assert!((diagonal.fidelity(&label("Z")) - (-0.4_f64).exp()).abs() < 1e-12); + } } diff --git a/exp/pecos-lindblad/src/synthesis.rs b/exp/pecos-lindblad/src/synthesis.rs index cd62b5f65..7eeb7f7b2 100644 --- a/exp/pecos-lindblad/src/synthesis.rs +++ b/exp/pecos-lindblad/src/synthesis.rs @@ -273,7 +273,7 @@ pub fn synthesize_exact_unitary(gate: &Gate) -> PauliLindbladModel { /// inverts via Walsh-Hadamard. pub fn synthesize_numerical(gate: &Gate, n_steps: usize) -> PauliLindbladModel { assert!( - n_steps >= 2 && n_steps % 2 == 0, + n_steps >= 2 && n_steps.is_multiple_of(2), "n_steps must be even and >= 2, got {}", n_steps ); diff --git a/exp/pecos-lindblad/tests/cross_path.rs b/exp/pecos-lindblad/tests/cross_path.rs index 65605c8d3..16ae23186 100644 --- a/exp/pecos-lindblad/tests/cross_path.rs +++ b/exp/pecos-lindblad/tests/cross_path.rs @@ -63,7 +63,7 @@ fn identity_2q_rates_agree_with_1q_independent_qubits() { let bp_l = 1.0 / t2_l - 1.0 / (2.0 * t1_l); let bp_r = 1.0 / t2_r - 1.0 / (2.0 * t1_r); - let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + let rate = |s: &str| pl.rate(&PauliString::from_label(s).unwrap()); assert_abs_diff_eq!(rate("IX"), bd_r * tau_g / 4.0, epsilon = 1e-12); assert_abs_diff_eq!(rate("IY"), bd_r * tau_g / 4.0, epsilon = 1e-12); assert_abs_diff_eq!(rate("IZ"), bp_r * tau_g / 2.0, epsilon = 1e-12); diff --git a/exp/pecos-lindblad/tests/cx_theta_2q.rs b/exp/pecos-lindblad/tests/cx_theta_2q.rs index 88e4d2517..30ce651b5 100644 --- a/exp/pecos-lindblad/tests/cx_theta_2q.rs +++ b/exp/pecos-lindblad/tests/cx_theta_2q.rs @@ -114,7 +114,7 @@ fn run_cx(theta: f64, omega: f64, bd_l: f64, bd_r: f64, bp_l: f64, bp_r: f64, to "IX", "IY", "IZ", "XI", "XX", "XY", "XZ", "YI", "YX", "YY", "YZ", "ZI", "ZX", "ZY", "ZZ", ]; for label in all_labels { - let got = pl.rate(&PauliString::from_str(label).unwrap()); + let got = pl.rate(&PauliString::from_label(label).unwrap()); let expected = paper_cx_rate(label, theta, omega, bd_l, bd_r, bp_l, bp_r); assert_abs_diff_eq!(got, expected, epsilon = tol); } diff --git a/exp/pecos-lindblad/tests/cz_theta_2q.rs b/exp/pecos-lindblad/tests/cz_theta_2q.rs index 65b54389b..892b87a7f 100644 --- a/exp/pecos-lindblad/tests/cz_theta_2q.rs +++ b/exp/pecos-lindblad/tests/cz_theta_2q.rs @@ -123,7 +123,7 @@ fn run_cz( beta_phi_l, beta_phi_r, ); - let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + let rate = |s: &str| pl.rate(&PauliString::from_label(s).unwrap()); assert_abs_diff_eq!(rate("IZ"), exp.iz, epsilon = tol); assert_abs_diff_eq!(rate("ZI"), exp.zi, epsilon = tol); diff --git a/exp/pecos-lindblad/tests/diff_helpers.rs b/exp/pecos-lindblad/tests/diff_helpers.rs index d278071bd..2490840cb 100644 --- a/exp/pecos-lindblad/tests/diff_helpers.rs +++ b/exp/pecos-lindblad/tests/diff_helpers.rs @@ -19,7 +19,7 @@ use pecos_lindblad::{PauliLindbladModel, PauliString}; fn model(entries: &[(&str, f64)]) -> PauliLindbladModel { let supports: Vec<_> = entries .iter() - .map(|(s, _)| PauliString::from_str(s).unwrap()) + .map(|(s, _)| PauliString::from_label(s).unwrap()) .collect(); let rates: Vec<_> = entries.iter().map(|(_, r)| *r).collect(); PauliLindbladModel::new(supports, rates) diff --git a/exp/pecos-lindblad/tests/expm_smoke.rs b/exp/pecos-lindblad/tests/expm_smoke.rs index eb291dc7f..2c1b3919a 100644 --- a/exp/pecos-lindblad/tests/expm_smoke.rs +++ b/exp/pecos-lindblad/tests/expm_smoke.rs @@ -47,7 +47,7 @@ fn expm_of_diagonal_is_elementwise_exp() { let d = 4; let mut m = matrix::zeros(d); m[0] = Complex64::new(0.5, 0.0); - m[1 * d + 1] = Complex64::new(-0.3, 0.0); + m[d + 1] = Complex64::new(-0.3, 0.0); m[2 * d + 2] = Complex64::new(0.0, 1.2); m[3 * d + 3] = Complex64::new(-0.1, -0.4); let result = matrix::expm(&m, d); diff --git a/exp/pecos-lindblad/tests/four_qubit_smoke.rs b/exp/pecos-lindblad/tests/four_qubit_smoke.rs index 2821c6a1d..121380595 100644 --- a/exp/pecos-lindblad/tests/four_qubit_smoke.rs +++ b/exp/pecos-lindblad/tests/four_qubit_smoke.rs @@ -64,7 +64,7 @@ fn four_qubit_identity_ad_on_one_qubit() { // on qubit 1 (index 1 from left in "qqqq" string). // lambda_IXII = lambda_IYII = beta_down * tau_g / 4 // lambda_IZII = beta_phi * tau_g / 2 - let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + let rate = |s: &str| pl.rate(&PauliString::from_label(s).unwrap()); assert_abs_diff_eq!(rate("IXII"), beta_down * tau_g / 4.0, epsilon = 1e-10); assert_abs_diff_eq!(rate("IYII"), beta_down * tau_g / 4.0, epsilon = 1e-10); assert_abs_diff_eq!(rate("IZII"), beta_phi * tau_g / 2.0, epsilon = 1e-10); @@ -97,7 +97,7 @@ fn four_qubit_identity_coherent_zzzz_smoke() { // lambda_ZZZZ = (delta * tau_g)^2 / 4 (by analogy with 1Q phase noise). let expected = (delta * tau_g).powi(2) / 4.0; assert_abs_diff_eq!( - pl.rate(&PauliString::from_str("ZZZZ").unwrap()), + pl.rate(&PauliString::from_label("ZZZZ").unwrap()), expected, epsilon = 1e-10 ); diff --git a/exp/pecos-lindblad/tests/inverse_fit.rs b/exp/pecos-lindblad/tests/inverse_fit.rs index e2d89ffd0..6193f6456 100644 --- a/exp/pecos-lindblad/tests/inverse_fit.rs +++ b/exp/pecos-lindblad/tests/inverse_fit.rs @@ -74,32 +74,32 @@ fn recovery_returns_none_on_zero_tau() { fn compose_independent_sums_rates() { let a = PauliLindbladModel::new( vec![ - PauliString::from_str("IX").unwrap(), - PauliString::from_str("ZZ").unwrap(), + PauliString::from_label("IX").unwrap(), + PauliString::from_label("ZZ").unwrap(), ], vec![0.001, 0.005], ); let b = PauliLindbladModel::new( vec![ - PauliString::from_str("IX").unwrap(), - PauliString::from_str("XI").unwrap(), + PauliString::from_label("IX").unwrap(), + PauliString::from_label("XI").unwrap(), ], vec![0.002, 0.003], ); let ab = a.compose_independent(&b); // Expected support: IX (merged), XI, ZZ. Rates: IX=0.003, XI=0.003, ZZ=0.005. assert_abs_diff_eq!( - ab.rate(&PauliString::from_str("IX").unwrap()), + ab.rate(&PauliString::from_label("IX").unwrap()), 0.003, epsilon = 1e-14 ); assert_abs_diff_eq!( - ab.rate(&PauliString::from_str("XI").unwrap()), + ab.rate(&PauliString::from_label("XI").unwrap()), 0.003, epsilon = 1e-14 ); assert_abs_diff_eq!( - ab.rate(&PauliString::from_str("ZZ").unwrap()), + ab.rate(&PauliString::from_label("ZZ").unwrap()), 0.005, epsilon = 1e-14 ); diff --git a/exp/pecos-lindblad/tests/inverse_fit_2q.rs b/exp/pecos-lindblad/tests/inverse_fit_2q.rs index 89b8cb250..7fde76826 100644 --- a/exp/pecos-lindblad/tests/inverse_fit_2q.rs +++ b/exp/pecos-lindblad/tests/inverse_fit_2q.rs @@ -84,7 +84,7 @@ fn recovery_residual_nonzero_under_model_mismatch() { // simulating measured rates that don't fit the pure-AD+PD form. let supports: Vec<_> = ["IX", "IY", "XI", "YI"] .iter() - .map(|s| PauliString::from_str(s).unwrap()) + .map(|s| PauliString::from_label(s).unwrap()) .collect(); // IX, IY differ by 20% (not allowed under pure AD+PD for CZ). let rates = vec![0.003, 0.0036, 0.002, 0.002]; @@ -100,12 +100,12 @@ fn recovery_residual_nonzero_under_model_mismatch() { #[test] fn recovery_returns_none_on_negative_rates() { let supports = vec![ - PauliString::from_str("IX").unwrap(), - PauliString::from_str("IY").unwrap(), - PauliString::from_str("XI").unwrap(), - PauliString::from_str("YI").unwrap(), - PauliString::from_str("IZ").unwrap(), - PauliString::from_str("ZI").unwrap(), + PauliString::from_label("IX").unwrap(), + PauliString::from_label("IY").unwrap(), + PauliString::from_label("XI").unwrap(), + PauliString::from_label("YI").unwrap(), + PauliString::from_label("IZ").unwrap(), + PauliString::from_label("ZI").unwrap(), ]; // lambda_ix is zero -> recovery can't infer beta_down_r. let rates = vec![0.0, 0.0, 0.001, 0.001, 0.002, 0.002]; diff --git a/exp/pecos-lindblad/tests/izz_crosstalk_3q.rs b/exp/pecos-lindblad/tests/izz_crosstalk_3q.rs index f8eaf932b..51e3ae982 100644 --- a/exp/pecos-lindblad/tests/izz_crosstalk_3q.rs +++ b/exp/pecos-lindblad/tests/izz_crosstalk_3q.rs @@ -101,6 +101,6 @@ fn izz_crosstalk_produces_only_weight_3_and_no_weight_2() { } // At least one weight-3 rate (e.g. lambda_iyz) should be non-zero. - let iyz = PauliString::from_str("IYZ").unwrap(); + let iyz = PauliString::from_label("IYZ").unwrap(); assert!(pl.rate(&iyz) > 1e-12); } diff --git a/exp/pecos-lindblad/tests/noise_budget.rs b/exp/pecos-lindblad/tests/noise_budget.rs index 175d91c91..26f1ac1e7 100644 --- a/exp/pecos-lindblad/tests/noise_budget.rs +++ b/exp/pecos-lindblad/tests/noise_budget.rs @@ -19,7 +19,7 @@ use pecos_lindblad::{PauliLindbladModel, PauliString}; fn model(entries: &[(&str, f64)]) -> PauliLindbladModel { let supports: Vec<_> = entries .iter() - .map(|(s, _)| PauliString::from_str(s).unwrap()) + .map(|(s, _)| PauliString::from_label(s).unwrap()) .collect(); let rates: Vec<_> = entries.iter().map(|(_, r)| *r).collect(); PauliLindbladModel::new(supports, rates) diff --git a/exp/pecos-lindblad/tests/noise_models_api.rs b/exp/pecos-lindblad/tests/noise_models_api.rs index e9b0b682c..f9ee9b57f 100644 --- a/exp/pecos-lindblad/tests/noise_models_api.rs +++ b/exp/pecos-lindblad/tests/noise_models_api.rs @@ -59,7 +59,7 @@ fn cx_theta_via_device_params_matches_hand_rolled() { let s2 = (2.0 * theta).sin(); let expected = (2.0 * theta + s2) / 16.0 * bd_l / omega; assert_abs_diff_eq!( - pl.rate(&PauliString::from_str("XI").unwrap()), + pl.rate(&PauliString::from_label("XI").unwrap()), expected, epsilon = 1e-8 ); @@ -79,7 +79,7 @@ fn coherent_phase_2q_via_api() { let gate = Gate::cz_theta(omega_cz, theta, noise); let pl = synthesize_exact_unitary(&gate); - let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + let rate = |s: &str| pl.rate(&PauliString::from_label(s).unwrap()); let factor = theta.powi(2) / 4.0 / omega_cz.powi(2); assert_abs_diff_eq!(rate("IZ"), factor * delta_iz.powi(2), epsilon = 1e-14); assert_abs_diff_eq!(rate("ZI"), factor * delta_zi.powi(2), epsilon = 1e-14); diff --git a/exp/pecos-lindblad/tests/phase_noise_2q.rs b/exp/pecos-lindblad/tests/phase_noise_2q.rs index 78b167eb0..9319adc87 100644 --- a/exp/pecos-lindblad/tests/phase_noise_2q.rs +++ b/exp/pecos-lindblad/tests/phase_noise_2q.rs @@ -18,10 +18,10 @@ //! //! Cases tested: //! - (i) Identity (H_g = 0): all three delta components commute with H_g, -//! so rates are quadratic-in-delta and decoupled (eq. 981). +//! so rates are quadratic-in-delta and decoupled (eq. 981). //! - (iii) CX_theta: phase noise doesn't commute with X_target, producing -//! mixing between delta_iz and delta_zz into lambda_iy, lambda_zy, -//! lambda_iz, lambda_zz (eqs. 986-990). +//! mixing between delta_iz and delta_zz into lambda_iy, lambda_zy, +//! lambda_iz, lambda_zz (eqs. 986-990). //! //! Synthesis path: `synthesize_exact_unitary` (coherent noise, no c_ops). @@ -63,7 +63,7 @@ fn identity_2q_phase_noise_commuting_case() { let gate = Gate::identity(2, noise, tau_g); let pl = synthesize_exact_unitary(&gate); - let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + let rate = |s: &str| pl.rate(&PauliString::from_label(s).unwrap()); assert_abs_diff_eq!( rate("IZ"), (delta_iz * tau_g).powi(2) / 4.0, @@ -108,7 +108,7 @@ fn cx_theta_phase_noise_mixing_case() { let gate = Gate::cx_theta(omega, theta, noise); let pl = synthesize_exact_unitary(&gate); - let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + let rate = |s: &str| pl.rate(&PauliString::from_label(s).unwrap()); let s2t = (2.0 * theta).sin(); let sin4 = theta.sin().powi(4); @@ -149,7 +149,7 @@ fn cz_theta_phase_noise_commuting_case() { let gate = Gate::cz_theta(omega_cz, theta, noise); let pl = synthesize_exact_unitary(&gate); - let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + let rate = |s: &str| pl.rate(&PauliString::from_label(s).unwrap()); let factor = theta.powi(2) / 4.0 / omega_cz.powi(2); assert_abs_diff_eq!(rate("IZ"), factor * delta_iz.powi(2), epsilon = 1e-14); assert_abs_diff_eq!(rate("ZI"), factor * delta_zi.powi(2), epsilon = 1e-14); @@ -175,7 +175,7 @@ fn cx_theta_phase_noise_pi_over_2() { let gate = Gate::cx_theta(omega, theta, noise); let pl = synthesize_exact_unitary(&gate); - let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + let rate = |s: &str| pl.rate(&PauliString::from_label(s).unwrap()); let expected = (2.0 * theta * (delta_iz + delta_zz)).powi(2) / (64.0 * omega.powi(2)); assert_abs_diff_eq!(rate("IZ"), expected, epsilon = 1e-9); assert_abs_diff_eq!(rate("ZZ"), expected, epsilon = 1e-9); diff --git a/exp/pecos-lindblad/tests/serde_roundtrip.rs b/exp/pecos-lindblad/tests/serde_roundtrip.rs index 513853c42..8d9f99834 100644 --- a/exp/pecos-lindblad/tests/serde_roundtrip.rs +++ b/exp/pecos-lindblad/tests/serde_roundtrip.rs @@ -32,7 +32,7 @@ fn pauli1_round_trip() { #[test] fn pauli_string_round_trip() { for s in ["I", "X", "Y", "Z", "IX", "XYZI", "ZZZZZ"] { - let ps = PauliString::from_str(s).unwrap(); + let ps = PauliString::from_label(s).unwrap(); let json = serde_json::to_string(&ps).unwrap(); let restored: PauliString = serde_json::from_str(&json).unwrap(); assert_eq!(ps, restored); @@ -69,8 +69,8 @@ fn pauli_lindblad_model_json_is_human_readable() { // inspect / hand-edit. let pl = PauliLindbladModel::new( vec![ - PauliString::from_str("X").unwrap(), - PauliString::from_str("Z").unwrap(), + PauliString::from_label("X").unwrap(), + PauliString::from_label("Z").unwrap(), ], vec![0.001, 0.002], ); diff --git a/exp/pecos-lindblad/tests/superop_synthesis.rs b/exp/pecos-lindblad/tests/superop_synthesis.rs index d56b0d583..4bdbe4bc4 100644 --- a/exp/pecos-lindblad/tests/superop_synthesis.rs +++ b/exp/pecos-lindblad/tests/superop_synthesis.rs @@ -103,7 +103,7 @@ fn superop_identity_handles_mixed_coherent_and_dissipative_2q() { let gate = Gate::identity(2, mixed, tau_g); let pl = synthesize_superop_identity(&gate); - let rate = |s: &str| pl.rate(&PauliString::from_str(s).unwrap()); + let rate = |s: &str| pl.rate(&PauliString::from_label(s).unwrap()); // Expected (leading-order superposition of independent contributions): // Dissipative (AD+PD) on each qubit contributes single-qubit rates diff --git a/exp/pecos-lindblad/tests/synthesize_superop_full.rs b/exp/pecos-lindblad/tests/synthesize_superop_full.rs index 6b5eab1a7..628b66010 100644 --- a/exp/pecos-lindblad/tests/synthesize_superop_full.rs +++ b/exp/pecos-lindblad/tests/synthesize_superop_full.rs @@ -121,7 +121,7 @@ fn superop_handles_cx_mixed_ad_pd_plus_coherent_zz() { } // Additional sanity: mixed has non-trivial rates from both sources. - let rate_mixed = |s: &str| pl_mixed.rate(&PauliString::from_str(s).unwrap()); + let rate_mixed = |s: &str| pl_mixed.rate(&PauliString::from_label(s).unwrap()); assert!( rate_mixed("IX") > 1e-8, "dissipative contribution should be present" diff --git a/exp/pecos-lindblad/tests/walsh_hadamard_roundtrip.rs b/exp/pecos-lindblad/tests/walsh_hadamard_roundtrip.rs index 5aa480a1d..55ad8a78a 100644 --- a/exp/pecos-lindblad/tests/walsh_hadamard_roundtrip.rs +++ b/exp/pecos-lindblad/tests/walsh_hadamard_roundtrip.rs @@ -61,7 +61,7 @@ fn inverse_walsh_hadamard(paulis: &[PauliString], alphas: &[f64], n_qubits: usiz fn round_trip(n_qubits: usize, seed_rates: &[(&str, f64)]) { let supports: Vec = seed_rates .iter() - .map(|(s, _)| PauliString::from_str(s).unwrap()) + .map(|(s, _)| PauliString::from_label(s).unwrap()) .collect(); let rates: Vec = seed_rates.iter().map(|(_, r)| *r).collect(); let model = PauliLindbladModel::new(supports.clone(), rates.clone()); From 0a70eaf047e4d39140f32a2a94e02cb6ed88f111 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 21:42:13 -0600 Subject: [PATCH 070/125] Pack F2Matrix storage --- crates/pecos-qec/src/stabilizer_code.rs | 10 +- crates/pecos-quantum/src/pauli_group.rs | 8 +- crates/pecos-quantum/src/pauli_sequence.rs | 359 +++++++++++++-------- 3 files changed, 234 insertions(+), 143 deletions(-) diff --git a/crates/pecos-qec/src/stabilizer_code.rs b/crates/pecos-qec/src/stabilizer_code.rs index 98fb30e56..6f1eb5780 100644 --- a/crates/pecos-qec/src/stabilizer_code.rs +++ b/crates/pecos-qec/src/stabilizer_code.rs @@ -147,10 +147,10 @@ impl StabilizerCode { let mut stab_mat = F2Matrix::zeros(num_generators, 2 * n); for (row_idx, stab) in self.group.stabilizers().iter().enumerate() { for q in stab.x_positions() { - stab_mat.row_mut(row_idx)[q] = 1; + stab_mat.set(row_idx, q, 1); } for q in stab.z_positions() { - stab_mat.row_mut(row_idx)[n + q] = 1; + stab_mat.set(row_idx, n + q, 1); } } let (stab_rref, stab_pivots) = stab_mat.row_reduce(); @@ -167,7 +167,7 @@ impl StabilizerCode { for (row_idx, &pivot_col) in stab_pivots.iter().enumerate() { if v[pivot_col] == 1 { for (col, vi) in v.iter_mut().enumerate() { - *vi ^= stab_rref.row(row_idx)[col]; + *vi ^= stab_rref.get(row_idx, col); } } } @@ -182,11 +182,11 @@ impl StabilizerCode { if logical_vecs.len() > 1 { let mut log_mat = F2Matrix::zeros(logical_vecs.len(), 2 * n); for (i, v) in logical_vecs.iter().enumerate() { - log_mat.row_mut(i).clone_from(v); + log_mat.set_row(i, v); } let (reduced, _) = log_mat.row_reduce(); logical_vecs = (0..reduced.num_rows()) - .map(|i| reduced.row(i).to_vec()) + .map(|i| reduced.row(i)) .filter(|r| r.iter().any(|&b| b != 0)) .collect(); } diff --git a/crates/pecos-quantum/src/pauli_group.rs b/crates/pecos-quantum/src/pauli_group.rs index ee28a329f..fe3889452 100644 --- a/crates/pecos-quantum/src/pauli_group.rs +++ b/crates/pecos-quantum/src/pauli_group.rs @@ -265,15 +265,15 @@ impl PauliGroup { for (row_idx, generator) in self.inner.paulis().iter().enumerate() { for q in generator.x_positions() { if q < n { - mat.rows[row_idx][q] = 1; + mat.set(row_idx, q, 1); } } for q in generator.z_positions() { if q < n { - mat.rows[row_idx][n + q] = 1; + mat.set(row_idx, n + q, 1); } } - mat.rows[row_idx][2 * n + row_idx] = 1; + mat.set(row_idx, 2 * n + row_idx, 1); } let (reduced, pivots) = mat.row_reduce(); @@ -295,7 +295,7 @@ impl PauliGroup { for (row_idx, &pivot_col) in pivots.iter().enumerate() { if target[pivot_col] == 1 { for (col, t) in target.iter_mut().enumerate() { - *t ^= reduced.rows[row_idx][col]; + *t ^= reduced.get(row_idx, col); } } } diff --git a/crates/pecos-quantum/src/pauli_sequence.rs b/crates/pecos-quantum/src/pauli_sequence.rs index a94aee614..c0b35fc84 100644 --- a/crates/pecos-quantum/src/pauli_sequence.rs +++ b/crates/pecos-quantum/src/pauli_sequence.rs @@ -50,30 +50,45 @@ use pecos_core::{ParsePauliStringError, PauliOperator, PauliString}; use std::fmt; use std::str::FromStr; -/// A binary matrix over GF(2), represented row-major. +/// A binary matrix over GF(2), represented row-major as packed `u64` words. /// /// Each row is a 2n-bit vector representing a Pauli string in the binary /// symplectic representation: `(x_0, ..., x_{n-1} | z_0, ..., z_{n-1})` /// where `x_q = 1` if qubit q has X or Y, and `z_q = 1` if qubit q has Z or Y. -/// -// TODO: Each bit is stored as a full `u8`. For large codes, consider packing -// into `u64` words or using a bitvec for 8x memory reduction. #[derive(Debug, Clone, PartialEq, Eq)] pub struct F2Matrix { - pub(crate) rows: Vec>, + rows: Vec>, num_cols: usize, } impl F2Matrix { + const WORD_BITS: usize = u64::BITS as usize; + /// Creates a new F2 matrix with the given dimensions, initialized to zero. #[must_use] pub fn zeros(num_rows: usize, num_cols: usize) -> Self { Self { - rows: vec![vec![0; num_cols]; num_rows], + rows: vec![vec![0; Self::num_words(num_cols)]; num_rows], num_cols, } } + /// Creates an F2 matrix from dense 0/1 rows. + /// + /// # Panics + /// + /// Panics if the rows do not all have the same length, or if any entry is + /// not 0 or 1. + #[must_use] + pub fn from_rows(rows: Vec>) -> Self { + let num_cols = rows.first().map_or(0, Vec::len); + let mut mat = Self::zeros(rows.len(), num_cols); + for (i, row) in rows.iter().enumerate() { + mat.set_row(i, row); + } + mat + } + /// Returns the number of rows. #[must_use] pub fn num_rows(&self) -> usize { @@ -88,32 +103,98 @@ impl F2Matrix { /// Returns a reference to the rows. #[must_use] - pub fn rows(&self) -> &[Vec] { - &self.rows + pub fn rows(&self) -> Vec> { + (0..self.num_rows()).map(|i| self.row(i)).collect() } - /// Returns a reference to a specific row. + /// Returns a dense copy of a specific row. #[must_use] - pub fn row(&self, i: usize) -> &[u8] { + pub fn row(&self, i: usize) -> Vec { + (0..self.num_cols).map(|col| self.get(i, col)).collect() + } + + /// Returns the packed words for a row. + #[must_use] + pub(crate) fn row_words(&self, i: usize) -> &[u64] { &self.rows[i] } - /// Returns a mutable reference to a specific row. - pub fn row_mut(&mut self, i: usize) -> &mut Vec { - &mut self.rows[i] + /// Returns a single matrix entry. + /// + /// # Panics + /// + /// Panics if `row` or `col` is out of bounds. + #[must_use] + pub fn get(&self, row: usize, col: usize) -> u8 { + assert!(col < self.num_cols); + let (word, mask) = Self::word_mask(col); + u8::from((self.rows[row][word] & mask) != 0) + } + + /// Sets a single matrix entry. + /// + /// # Panics + /// + /// Panics if `row` or `col` is out of bounds, or if `value` is not 0 or 1. + pub fn set(&mut self, row: usize, col: usize, value: u8) { + assert!(col < self.num_cols); + assert!(value <= 1, "F2Matrix entries must be 0 or 1"); + let (word, mask) = Self::word_mask(col); + if value == 0 { + self.rows[row][word] &= !mask; + } else { + self.rows[row][word] |= mask; + } + } + + /// Replaces one row from a dense 0/1 slice. + /// + /// # Panics + /// + /// Panics if the row length does not match `num_cols`, or if any entry is + /// not 0 or 1. + pub fn set_row(&mut self, row: usize, bits: &[u8]) { + assert_eq!(bits.len(), self.num_cols); + self.rows[row].fill(0); + for (col, &bit) in bits.iter().enumerate() { + if bit != 0 { + assert_eq!(bit, 1, "F2Matrix entries must be 0 or 1"); + self.set(row, col, 1); + } + } } /// Checks if a row is all zeros. #[must_use] pub fn is_zero_row(&self, i: usize) -> bool { - self.rows[i].iter().all(|&b| b == 0) + self.rows[i].iter().all(|&word| word == 0) } /// XORs row `src` into row `dst` (row[dst] ^= row[src]). fn xor_row(&mut self, dst: usize, src: usize) { - // Avoid borrow issues by doing index operations - for col in 0..self.num_cols { - self.rows[dst][col] ^= self.rows[src][col]; + if dst == src { + self.rows[dst].fill(0); + return; + } + let src_row = self.rows[src].clone(); + for (dst_word, src_word) in self.rows[dst].iter_mut().zip(src_row) { + *dst_word ^= src_word; + } + self.clear_unused_bits(dst); + } + + fn xor_row_into_dense(&self, row: usize, dense: &mut [u8]) { + assert_eq!(dense.len(), self.num_cols); + for word_idx in 0..self.rows[row].len() { + let mut word = self.rows[row][word_idx]; + while word != 0 { + let bit = word.trailing_zeros() as usize; + let col = word_idx * Self::WORD_BITS + bit; + if col < self.num_cols { + dense[col] ^= 1; + } + word &= word - 1; + } } } @@ -122,6 +203,40 @@ impl F2Matrix { self.rows.swap(a, b); } + fn num_words(num_cols: usize) -> usize { + num_cols.div_ceil(Self::WORD_BITS) + } + + fn word_mask(col: usize) -> (usize, u64) { + let word = col / Self::WORD_BITS; + let bit = col % Self::WORD_BITS; + (word, 1u64 << bit) + } + + fn last_word_mask(&self) -> u64 { + let rem = self.num_cols % Self::WORD_BITS; + if rem == 0 { + u64::MAX + } else { + (1u64 << rem) - 1 + } + } + + fn clear_unused_bits(&mut self, row: usize) { + if self.num_cols == 0 { + return; + } + let mask = self.last_word_mask(); + if let Some(last) = self.rows[row].last_mut() { + *last &= mask; + } + } + + fn row_has_bit(&self, row: usize, col: usize) -> bool { + let (word, mask) = Self::word_mask(col); + (self.rows[row][word] & mask) != 0 + } + /// Performs Gaussian elimination over GF(2), returning the row echelon form /// and the pivot column positions. /// @@ -137,7 +252,7 @@ impl F2Matrix { // Find a row with a 1 in this column at or below pivot_row let mut found = None; for row in pivot_row..mat.num_rows() { - if mat.rows[row][col] == 1 { + if mat.row_has_bit(row, col) { found = Some(row); break; } @@ -152,7 +267,7 @@ impl F2Matrix { // Eliminate all other rows with a 1 in this column for row in 0..mat.num_rows() { - if row != pivot_row && mat.rows[row][col] == 1 { + if row != pivot_row && mat.row_has_bit(row, col) { mat.xor_row(row, pivot_row); } } @@ -169,7 +284,7 @@ impl F2Matrix { pub fn identity(n: usize) -> Self { let mut mat = Self::zeros(n, n); for i in 0..n { - mat.rows[i][i] = 1; + mat.set(i, i, 1); } mat } @@ -188,9 +303,9 @@ impl F2Matrix { let mut aug = Self::zeros(n, 2 * n); for i in 0..n { for j in 0..n { - aug.rows[i][j] = self.rows[i][j]; + aug.set(i, j, self.get(i, j)); } - aug.rows[i][n + i] = 1; + aug.set(i, n + i, 1); } // Row-reduce the augmented matrix. @@ -199,7 +314,7 @@ impl F2Matrix { // Find pivot in this column at or below the diagonal let mut found = None; for row in col..n { - if aug.rows[row][col] == 1 { + if aug.row_has_bit(row, col) { found = Some(row); break; } @@ -212,7 +327,7 @@ impl F2Matrix { // Eliminate all other rows for row in 0..n { - if row != col && aug.rows[row][col] == 1 { + if row != col && aug.row_has_bit(row, col) { aug.xor_row(row, col); } } @@ -221,7 +336,9 @@ impl F2Matrix { // Extract the inverse from the right half let mut inv = Self::zeros(n, n); for i in 0..n { - inv.rows[i] = aug.rows[i][n..2 * n].to_vec(); + for j in 0..n { + inv.set(i, j, aug.get(i, n + j)); + } } Some(inv) } @@ -237,13 +354,16 @@ impl F2Matrix { let m = self.num_rows(); let p = other.num_cols; let mut result = Self::zeros(m, p); + let other_t = other.transpose(); for i in 0..m { for j in 0..p { - let mut sum = 0u8; - for k in 0..self.num_cols { - sum ^= self.rows[i][k] & other.rows[k][j]; + let mut parity = 0u32; + for (a, b) in self.rows[i].iter().zip(other_t.row_words(j)) { + parity ^= (a & b).count_ones() & 1; + } + if parity != 0 { + result.set(i, j, 1); } - result.rows[i][j] = sum; } } result @@ -257,7 +377,7 @@ impl F2Matrix { let mut result = Self::zeros(n, m); for i in 0..m { for j in 0..n { - result.rows[j][i] = self.rows[i][j]; + result.set(j, i, self.get(i, j)); } } result @@ -275,7 +395,7 @@ impl F2Matrix { let mut aug = Self::zeros(m, n + n); for i in 0..m { for j in 0..n { - aug.rows[i][j] = self.rows[i][j]; + aug.set(i, j, self.get(i, j)); } } // We actually need to work with the transpose to find the right kernel. @@ -287,12 +407,12 @@ impl F2Matrix { let mut at = Self::zeros(n, m + n); for i in 0..m { for j in 0..n { - at.rows[j][i] = self.rows[i][j]; + at.set(j, i, self.get(i, j)); } } // Augment with identity in the right block for j in 0..n { - at.rows[j][m + j] = 1; + at.set(j, m + j, 1); } // Row-reduce A^T @@ -300,11 +420,11 @@ impl F2Matrix { // Rows that are zero in the A^T part (columns 0..m) give kernel vectors // from the identity part (columns m..m+n). - let mut basis = Vec::new(); + let mut basis: Vec> = Vec::new(); for i in 0..n { - if reduced.rows[i][..m].iter().all(|&b| b == 0) { + if (0..m).all(|col| reduced.get(i, col) == 0) { // This row's right block is a kernel vector - basis.push(reduced.rows[i][m..m + n].to_vec()); + basis.push((m..m + n).map(|col| reduced.get(i, col)).collect()); } } @@ -316,20 +436,14 @@ impl F2Matrix { // Handle overcounting: only keep linearly independent vectors if basis.len() > 1 { - let check = Self { - rows: basis.clone(), - num_cols: n, - }; + let check = Self::from_rows(basis.clone()); let (_, _ind_pivots) = check.row_reduce(); // The first ind_pivots.len() rows of the reduced form are independent // but we want the original basis vectors. Since we sorted, just take // the independent count. Actually, let's re-reduce properly. let (reduced_basis, _) = check.row_reduce(); - basis = reduced_basis - .rows - .into_iter() - .filter(|r| r.iter().any(|&b| b != 0)) - .collect(); + basis = reduced_basis.rows(); + basis.retain(|r| r.iter().any(|&b| b != 0)); } basis @@ -338,17 +452,17 @@ impl F2Matrix { impl fmt::Display for F2Matrix { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - for (i, row) in self.rows.iter().enumerate() { + for i in 0..self.num_rows() { if i > 0 { writeln!(f)?; } // Show the X block and Z block separated by | let n = self.num_cols / 2; - for (j, &bit) in row.iter().enumerate() { + for j in 0..self.num_cols { if j == n { write!(f, "|")?; } - write!(f, "{bit}")?; + write!(f, "{}", self.get(i, j))?; } } Ok(()) @@ -501,10 +615,10 @@ impl PauliSequence { for (row_idx, generator) in self.paulis.iter().enumerate() { for q in generator.x_positions() { - mat.rows[row_idx][q] = 1; + mat.set(row_idx, q, 1); } for q in generator.z_positions() { - mat.rows[row_idx][n + q] = 1; + mat.set(row_idx, n + q, 1); } } @@ -583,9 +697,7 @@ impl PauliSequence { // Eliminate the target using the reduced generators' pivots for (row_idx, &pivot_col) in pivots.iter().enumerate() { if target[pivot_col] == 1 { - for (col, t) in target.iter_mut().enumerate() { - *t ^= reduced.rows[row_idx][col]; - } + reduced.xor_row_into_dense(row_idx, &mut target); } } @@ -614,12 +726,12 @@ impl PauliSequence { for (row_idx, generator) in self.paulis.iter().enumerate() { for q in generator.x_positions() { - mat.rows[row_idx][q] = 1; + mat.set(row_idx, q, 1); } for q in generator.z_positions() { - mat.rows[row_idx][n + q] = 1; + mat.set(row_idx, n + q, 1); } - mat.rows[row_idx][2 * n + row_idx] = 1; + mat.set(row_idx, 2 * n + row_idx, 1); } let (reduced, pivots) = mat.row_reduce(); @@ -636,9 +748,7 @@ impl PauliSequence { // Eliminate the target using the reduced rows for (row_idx, &pivot_col) in pivots.iter().enumerate() { if target[pivot_col] == 1 { - for (col, t) in target.iter_mut().enumerate() { - *t ^= reduced.rows[row_idx][col]; - } + reduced.xor_row_into_dense(row_idx, &mut target); } } @@ -722,7 +832,7 @@ impl PauliSequence { for col in 0..mat.num_cols { let mut found = None; for row in pivot_row..k { - if mat.rows[row][col] == 1 { + if mat.get(row, col) == 1 { found = Some(row); break; } @@ -736,7 +846,7 @@ impl PauliSequence { paulis.swap(pivot_row, found_row); for row in 0..k { - if row != pivot_row && mat.rows[row][col] == 1 { + if row != pivot_row && mat.get(row, col) == 1 { mat.xor_row(row, pivot_row); let pivot_ps = paulis[pivot_row].clone(); paulis[row] = paulis[row].clone() * pivot_ps; @@ -785,12 +895,12 @@ impl PauliSequence { for (row_idx, generator) in self.paulis.iter().enumerate() { for q in generator.x_positions() { if q < n { - mat.rows[row_idx][q] = 1; + mat.set(row_idx, q, 1); } } for q in generator.z_positions() { if q < n { - mat.rows[row_idx][n + q] = 1; + mat.set(row_idx, n + q, 1); } } } @@ -799,8 +909,8 @@ impl PauliSequence { let mut s_omega = F2Matrix::zeros(mat.num_rows(), 2 * n); for i in 0..mat.num_rows() { for j in 0..n { - s_omega.rows[i][j] = mat.rows[i][n + j]; // Z block -> first half - s_omega.rows[i][n + j] = mat.rows[i][j]; // X block -> second half + s_omega.set(i, j, mat.get(i, n + j)); // Z block -> first half + s_omega.set(i, n + j, mat.get(i, j)); // X block -> second half } } @@ -1200,9 +1310,7 @@ mod tests { #[test] fn test_f2_kernel() { // Identity matrix: kernel is empty - let mut mat = F2Matrix::zeros(2, 2); - mat.rows[0][0] = 1; - mat.rows[1][1] = 1; + let mat = F2Matrix::from_rows(vec![vec![1, 0], vec![0, 1]]); assert!(mat.kernel().is_empty()); // Zero matrix 2x3: kernel dimension = 3 @@ -1213,9 +1321,7 @@ mod tests { #[test] fn test_f2_kernel_rank_deficient() { // [[1,0,0],[1,0,0]]: rank 1, kernel dimension = 3 - 1 = 2 - let mut mat = F2Matrix::zeros(2, 3); - mat.rows[0][0] = 1; - mat.rows[1][0] = 1; + let mat = F2Matrix::from_rows(vec![vec![1, 0, 0], vec![1, 0, 0]]); let kern = mat.kernel(); assert_eq!(kern.len(), 2); // Each kernel vector should satisfy A * v = 0 @@ -1230,9 +1336,7 @@ mod tests { #[test] fn test_f2_kernel_rectangular() { // 1x4 matrix [1,1,0,0]: kernel dim = 3 - let mut mat = F2Matrix::zeros(1, 4); - mat.rows[0][0] = 1; - mat.rows[0][1] = 1; + let mat = F2Matrix::from_rows(vec![vec![1, 1, 0, 0]]); let kern = mat.kernel(); assert_eq!(kern.len(), 3); } @@ -1304,24 +1408,21 @@ mod tests { let seq = PauliSequence::new(vec![Y(0)]); let mat = seq.to_symplectic_matrix(); // For 1 qubit, symplectic vector is [x0, z0] - assert_eq!(mat.rows[0], vec![1, 1], "Y should set both x and z bits"); + assert_eq!(mat.row(0), vec![1, 1], "Y should set both x and z bits"); } #[test] fn test_f2_matrix_row_reduce_empty() { let mat = F2Matrix::zeros(0, 3); let (reduced, pivots) = mat.row_reduce(); - assert!(reduced.rows.is_empty()); + assert_eq!(reduced.num_rows(), 0); assert!(pivots.is_empty()); } #[test] fn test_f2_matrix_kernel_tall_matrix() { // More rows than columns: 3x2 matrix - let mut mat = F2Matrix::zeros(3, 2); - mat.rows[0] = vec![1, 0]; - mat.rows[1] = vec![0, 1]; - mat.rows[2] = vec![1, 1]; // row 2 = row 0 + row 1 (redundant) + let mat = F2Matrix::from_rows(vec![vec![1, 0], vec![0, 1], vec![1, 1]]); // Full column rank => kernel is empty let kern = mat.kernel(); assert!( @@ -1333,10 +1434,7 @@ mod tests { #[test] fn test_f2_matrix_kernel_identity() { // Identity matrix: full rank, trivial kernel - let mut mat = F2Matrix::zeros(3, 3); - mat.rows[0] = vec![1, 0, 0]; - mat.rows[1] = vec![0, 1, 0]; - mat.rows[2] = vec![0, 0, 1]; + let mat = F2Matrix::identity(3); let kern = mat.kernel(); assert!(kern.is_empty()); } @@ -1382,9 +1480,7 @@ mod tests { #[test] fn test_f2_invert_swap_matrix() { // Swap rows 0 and 1: [[0,1],[1,0]] - let mut m = F2Matrix::zeros(2, 2); - m.rows[0][1] = 1; - m.rows[1][0] = 1; + let m = F2Matrix::from_rows(vec![vec![0, 1], vec![1, 0]]); let inv = m.invert().unwrap(); // Swap is self-inverse assert_eq!(inv, m); @@ -1393,10 +1489,7 @@ mod tests { #[test] fn test_f2_invert_upper_triangular() { // [[1,1],[0,1]] over GF(2) is self-inverse - let mut m = F2Matrix::zeros(2, 2); - m.rows[0][0] = 1; - m.rows[0][1] = 1; - m.rows[1][1] = 1; + let m = F2Matrix::from_rows(vec![vec![1, 1], vec![0, 1]]); let inv = m.invert().unwrap(); assert_eq!(inv, m); } @@ -1404,9 +1497,7 @@ mod tests { #[test] fn test_f2_invert_singular() { // [[1,1],[1,1]] is singular - let mut m = F2Matrix::zeros(2, 2); - m.rows[0] = vec![1, 1]; - m.rows[1] = vec![1, 1]; + let m = F2Matrix::from_rows(vec![vec![1, 1], vec![1, 1]]); assert!(m.invert().is_none()); } @@ -1419,26 +1510,18 @@ mod tests { #[test] fn test_f2_mul() { // [[1,1],[0,1]] * [[1,0],[1,1]] = [[0,1],[1,1]] over GF(2) - let mut a = F2Matrix::zeros(2, 2); - a.rows[0] = vec![1, 1]; - a.rows[1] = vec![0, 1]; - - let mut b = F2Matrix::zeros(2, 2); - b.rows[0] = vec![1, 0]; - b.rows[1] = vec![1, 1]; + let a = F2Matrix::from_rows(vec![vec![1, 1], vec![0, 1]]); + let b = F2Matrix::from_rows(vec![vec![1, 0], vec![1, 1]]); let c = a.mul(&b); - assert_eq!(c.rows[0], vec![0, 1]); - assert_eq!(c.rows[1], vec![1, 1]); + assert_eq!(c.row(0), vec![0, 1]); + assert_eq!(c.row(1), vec![1, 1]); } #[test] fn test_f2_mul_inverse_gives_identity() { // Invertible 3x3 matrix over GF(2) - let mut m = F2Matrix::zeros(3, 3); - m.rows[0] = vec![1, 1, 0]; - m.rows[1] = vec![0, 1, 1]; - m.rows[2] = vec![1, 1, 1]; + let m = F2Matrix::from_rows(vec![vec![1, 1, 0], vec![0, 1, 1], vec![1, 1, 1]]); let inv = m.invert().unwrap(); let product = m.mul(&inv); @@ -1451,15 +1534,13 @@ mod tests { #[test] fn test_f2_transpose() { - let mut m = F2Matrix::zeros(2, 3); - m.rows[0] = vec![1, 0, 1]; - m.rows[1] = vec![0, 1, 0]; + let m = F2Matrix::from_rows(vec![vec![1, 0, 1], vec![0, 1, 0]]); let t = m.transpose(); assert_eq!(t.num_rows(), 3); assert_eq!(t.num_cols(), 2); - assert_eq!(t.rows[0], vec![1, 0]); - assert_eq!(t.rows[1], vec![0, 1]); - assert_eq!(t.rows[2], vec![1, 0]); + assert_eq!(t.row(0), vec![1, 0]); + assert_eq!(t.row(1), vec![0, 1]); + assert_eq!(t.row(2), vec![1, 0]); } // ======================================================================== @@ -1536,16 +1617,15 @@ mod tests { #[test] fn test_f2_identity_1x1() { let id = F2Matrix::identity(1); - assert_eq!(id.rows[0], vec![1]); + assert_eq!(id.row(0), vec![1]); } #[test] fn test_f2_invert_1x1() { // [[1]] is invertible - let mut m = F2Matrix::zeros(1, 1); - m.rows[0] = vec![1]; + let m = F2Matrix::identity(1); let inv = m.invert().unwrap(); - assert_eq!(inv.rows[0], vec![1]); + assert_eq!(inv.row(0), vec![1]); // [[0]] is not invertible let z = F2Matrix::zeros(1, 1); @@ -1555,10 +1635,7 @@ mod tests { #[test] fn test_f2_mul_identity() { let id = F2Matrix::identity(3); - let mut m = F2Matrix::zeros(3, 3); - m.rows[0] = vec![1, 1, 0]; - m.rows[1] = vec![0, 1, 1]; - m.rows[2] = vec![1, 1, 1]; + let m = F2Matrix::from_rows(vec![vec![1, 1, 0], vec![0, 1, 1], vec![1, 1, 1]]); // I * A = A assert_eq!(id.mul(&m), m); @@ -1566,21 +1643,34 @@ mod tests { assert_eq!(m.mul(&id), m); } + #[test] + fn test_f2_matrix_crosses_multiple_words() { + let mut m = F2Matrix::zeros(3, 130); + m.set(0, 0, 1); + m.set(0, 64, 1); + m.set(1, 65, 1); + m.set(2, 129, 1); + + assert_eq!(m.get(0, 0), 1); + assert_eq!(m.get(0, 64), 1); + assert_eq!(m.get(1, 65), 1); + assert_eq!(m.get(2, 129), 1); + let (_, pivots) = m.row_reduce(); + assert_eq!(pivots.len(), 3); + assert_eq!(m.transpose().transpose(), m); + } + #[test] fn test_f2_transpose_square() { - let mut m = F2Matrix::zeros(2, 2); - m.rows[0] = vec![1, 1]; - m.rows[1] = vec![0, 1]; + let m = F2Matrix::from_rows(vec![vec![1, 1], vec![0, 1]]); let t = m.transpose(); - assert_eq!(t.rows[0], vec![1, 0]); - assert_eq!(t.rows[1], vec![1, 1]); + assert_eq!(t.row(0), vec![1, 0]); + assert_eq!(t.row(1), vec![1, 1]); } #[test] fn test_f2_double_transpose() { - let mut m = F2Matrix::zeros(2, 3); - m.rows[0] = vec![1, 0, 1]; - m.rows[1] = vec![0, 1, 0]; + let m = F2Matrix::from_rows(vec![vec![1, 0, 1], vec![0, 1, 0]]); let tt = m.transpose().transpose(); assert_eq!(tt, m); } @@ -1588,11 +1678,12 @@ mod tests { #[test] fn test_f2_invert_4x4() { // A larger invertible matrix over GF(2) - let mut m = F2Matrix::zeros(4, 4); - m.rows[0] = vec![1, 0, 0, 1]; - m.rows[1] = vec![0, 1, 0, 1]; - m.rows[2] = vec![0, 0, 1, 1]; - m.rows[3] = vec![1, 1, 1, 0]; + let m = F2Matrix::from_rows(vec![ + vec![1, 0, 0, 1], + vec![0, 1, 0, 1], + vec![0, 0, 1, 1], + vec![1, 1, 1, 0], + ]); let inv = m.invert().unwrap(); assert_eq!(m.mul(&inv), F2Matrix::identity(4)); From ec691cdc032ecbb671a15c3f7ec7fde866e551a9 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 21:53:24 -0600 Subject: [PATCH 071/125] Add entanglement measures --- crates/pecos-quantum/src/lib.rs | 6 +- crates/pecos-quantum/src/measures.rs | 493 ++++++++++++++++++++++++++- 2 files changed, 496 insertions(+), 3 deletions(-) diff --git a/crates/pecos-quantum/src/lib.rs b/crates/pecos-quantum/src/lib.rs index 241d83c32..146b557ab 100644 --- a/crates/pecos-quantum/src/lib.rs +++ b/crates/pecos-quantum/src/lib.rs @@ -107,8 +107,10 @@ pub use channel::{ random_1q_clifford, random_2q_clifford, random_clifford, random_pauli, }; pub use measures::{ - MeasureError, average_gate_fidelity, entropy, entropy_with_base, gate_error, process_fidelity, - purity, state_fidelity, state_fidelity_with_density_matrix, + DensityMatrixPartialTrace, MeasureError, average_gate_fidelity, concurrence, + entanglement_of_formation, entropy, entropy_with_base, gate_error, mutual_information, + partial_trace_qubits, partial_trace_subsystems, process_fidelity, purity, state_fidelity, + state_fidelity_with_density_matrix, }; // Re-export operator matrix types for convenient method-style matrix conversion diff --git a/crates/pecos-quantum/src/measures.rs b/crates/pecos-quantum/src/measures.rs index 8e9831164..847aff6a4 100644 --- a/crates/pecos-quantum/src/measures.rs +++ b/crates/pecos-quantum/src/measures.rs @@ -18,7 +18,7 @@ use std::error::Error; use std::fmt; -use nalgebra::{DMatrix, DVector, SVD}; +use nalgebra::{DMatrix, DVector, SVD, Schur}; use num_complex::Complex64; use crate::channel::Ptm; @@ -95,6 +95,27 @@ pub enum MeasureError { /// Invalid base. base: f64, }, + /// Subsystem dimensions are invalid for a multipartite measure. + InvalidSubsystemDimensions { + /// Subsystem dimensions supplied by the caller. + dims: Vec, + /// Actual Hilbert-space dimension of the density matrix. + matrix_dim: usize, + }, + /// A subsystem index is outside the supplied tensor-factor list. + SubsystemOutOfRange { + /// Number of subsystems supplied by the caller. + num_subsystems: usize, + /// Invalid subsystem index. + subsystem: usize, + }, + /// A subsystem was listed more than once. + DuplicateSubsystem { + /// Repeated subsystem index. + subsystem: usize, + }, + /// An eigendecomposition did not converge. + EigenDecompositionFailed, } impl fmt::Display for MeasureError { @@ -149,12 +170,86 @@ impl fmt::Display for MeasureError { "entropy logarithm base must be finite, positive, and not 1; got {base}" ) } + Self::InvalidSubsystemDimensions { dims, matrix_dim } => write!( + f, + "invalid subsystem dimensions {dims:?} for density matrix dimension {matrix_dim}" + ), + Self::SubsystemOutOfRange { + num_subsystems, + subsystem, + } => write!( + f, + "subsystem {subsystem} is outside the {num_subsystems}-subsystem tensor product" + ), + Self::DuplicateSubsystem { subsystem } => { + write!(f, "duplicate subsystem index: {subsystem}") + } + Self::EigenDecompositionFailed => write!(f, "eigendecomposition failed"), } } } impl Error for MeasureError {} +/// Method-style partial trace operations for state density matrices. +/// +/// This trait is implemented for `DMatrix` because PECOS currently +/// represents state density matrices as dense complex matrices. The methods +/// validate that the matrix is a trace-one Hermitian density matrix before +/// reducing it. +pub trait DensityMatrixPartialTrace { + /// Returns the reduced density matrix after tracing out selected + /// tensor-product subsystems. + /// + /// `dims[i]` is the Hilbert-space dimension of subsystem `i`. Subsystem 0 + /// is the fastest-varying factor in the computational-basis index. + /// + /// # Errors + /// + /// Returns an error when the matrix is not a structurally valid density + /// matrix, when `dims` do not match its shape, or when `traced_subsystems` + /// contains an out-of-range or repeated subsystem. + fn partial_trace( + &self, + dims: &[usize], + traced_subsystems: &[usize], + ) -> Result, MeasureError>; + + /// Returns the reduced density matrix after tracing out selected qubits. + /// + /// Qubit indexing is little-endian: qubit 0 is the least-significant bit + /// of the computational-basis index. + /// + /// # Errors + /// + /// Returns an error when the matrix is not a structurally valid density + /// matrix, when its shape is not `2^num_qubits x 2^num_qubits`, or when + /// `traced_qubits` contains an out-of-range or repeated qubit. + fn partial_trace_qubits( + &self, + num_qubits: usize, + traced_qubits: &[usize], + ) -> Result, MeasureError>; +} + +impl DensityMatrixPartialTrace for DMatrix { + fn partial_trace( + &self, + dims: &[usize], + traced_subsystems: &[usize], + ) -> Result, MeasureError> { + partial_trace_subsystems(self, dims, traced_subsystems) + } + + fn partial_trace_qubits( + &self, + num_qubits: usize, + traced_qubits: &[usize], + ) -> Result, MeasureError> { + partial_trace_qubits(self, num_qubits, traced_qubits) + } +} + /// Returns pure-state fidelity `||^2`. /// /// Both state vectors must have the same length and be normalized. @@ -322,6 +417,181 @@ pub fn gate_error(left: &Ptm, right: &Ptm) -> Result { Ok(1.0 - average_gate_fidelity(left, right)?) } +/// Returns the two-qubit concurrence of a density matrix. +/// +/// For a two-qubit state `rho`, this computes Wootters' concurrence using the +/// spin-flipped matrix `rho_tilde = (Y ⊗ Y) rho* (Y ⊗ Y)` and the square roots +/// of the eigenvalues of `rho rho_tilde`. +/// +/// # Errors +/// +/// Returns an error when `rho` is not a structurally valid 4x4 density matrix, +/// or when the eigendecomposition fails. +pub fn concurrence(rho: &DMatrix) -> Result { + validate_density_matrix(rho)?; + if rho.nrows() != 4 || rho.ncols() != 4 { + return Err(MeasureError::InvalidMatrixShape { + expected_rows: 4, + expected_cols: 4, + rows: rho.nrows(), + cols: rho.ncols(), + }); + } + + let yy = pauli_y_tensor_pauli_y(); + let rho_conj = rho.map(|value| value.conj()); + let rho_tilde = &yy * rho_conj * yy; + let product = rho * rho_tilde; + let eigenvalues = Schur::try_new(product, DEFAULT_TOLERANCE, 0) + .and_then(|schur| schur.eigenvalues()) + .ok_or(MeasureError::EigenDecompositionFailed)?; + + let mut roots: Vec = eigenvalues + .iter() + .map(|lambda| { + if lambda.im.abs() <= 1e-8 { + lambda.re.max(0.0).sqrt() + } else { + lambda.norm().sqrt() + } + }) + .collect(); + roots.sort_by(|a, b| b.total_cmp(a)); + let value = roots[0] - roots[1] - roots[2] - roots[3]; + Ok(value.max(0.0).min(1.0)) +} + +/// Returns the two-qubit entanglement of formation. +/// +/// This is derived from [`concurrence`] as +/// `h((1 + sqrt(1 - C^2)) / 2)`, where `h` is binary entropy. +/// +/// # Errors +/// +/// Returns an error when [`concurrence`] fails. +pub fn entanglement_of_formation(rho: &DMatrix) -> Result { + let concurrence = concurrence(rho)?; + let argument = (1.0 + (1.0 - concurrence * concurrence).max(0.0).sqrt()) / 2.0; + Ok(binary_entropy(argument)) +} + +/// Returns the reduced density matrix after tracing out selected subsystems. +/// +/// `dims[i]` is the Hilbert-space dimension of subsystem `i`. Subsystem 0 is +/// the fastest-varying factor in the computational-basis index, matching PECOS +/// little-endian qubit ordering. The returned density matrix keeps untraced +/// subsystems in ascending subsystem-index order. +/// +/// # Errors +/// +/// Returns an error when `rho` is not a structurally valid density matrix, +/// when the product of `dims` does not match `rho`, or when +/// `traced_subsystems` contains an out-of-range or repeated subsystem. +pub fn partial_trace_subsystems( + rho: &DMatrix, + dims: &[usize], + traced_subsystems: &[usize], +) -> Result, MeasureError> { + validate_density_matrix(rho)?; + validate_subsystem_dimensions(rho, dims)?; + + let mut traced = traced_subsystems.to_vec(); + traced.sort_unstable(); + for window in traced.windows(2) { + if window[0] == window[1] { + return Err(MeasureError::DuplicateSubsystem { + subsystem: window[0], + }); + } + } + for &subsystem in &traced { + if subsystem >= dims.len() { + return Err(MeasureError::SubsystemOutOfRange { + num_subsystems: dims.len(), + subsystem, + }); + } + } + + let kept: Vec = (0..dims.len()) + .filter(|subsystem| traced.binary_search(subsystem).is_err()) + .collect(); + let out_dim = subsystem_product(dims, &kept)?; + let traced_dim = subsystem_product(dims, &traced)?; + let strides = subsystem_strides(dims)?; + + let mut out = DMatrix::zeros(out_dim, out_dim); + for kept_row in 0..out_dim { + for kept_col in 0..out_dim { + let mut value = Complex64::new(0.0, 0.0); + for traced_idx in 0..traced_dim { + let row = + embed_subsystem_index(dims, &strides, &kept, kept_row, &traced, traced_idx); + let col = + embed_subsystem_index(dims, &strides, &kept, kept_col, &traced, traced_idx); + value += rho[(row, col)]; + } + out[(kept_row, kept_col)] = value; + } + } + Ok(out) +} + +/// Returns the reduced density matrix after tracing out selected qubits. +/// +/// Qubit indexing is little-endian: qubit 0 is the least-significant bit of +/// the computational-basis index. The returned density matrix keeps untraced +/// qubits in ascending qubit-index order. +/// +/// # Errors +/// +/// Returns an error when `rho` is not a structurally valid density matrix, when +/// its shape is not `2^num_qubits x 2^num_qubits`, or when `traced_qubits` +/// contains an out-of-range or repeated qubit. +pub fn partial_trace_qubits( + rho: &DMatrix, + num_qubits: usize, + traced_qubits: &[usize], +) -> Result, MeasureError> { + let dims = vec![2; num_qubits]; + partial_trace_subsystems(rho, &dims, traced_qubits) +} + +/// Returns bipartite quantum mutual information. +/// +/// `dims` is `(dim_a, dim_b)`, and `rho` must have shape +/// `(dim_a * dim_b) x (dim_a * dim_b)`. Subsystem `A` is the fastest-varying +/// factor in the computational-basis index, matching +/// [`partial_trace_subsystems`]. +/// +/// # Errors +/// +/// Returns an error when `rho` is not a structurally valid density matrix, when +/// `dims` are invalid, or when entropy evaluation fails on a reduced state. +pub fn mutual_information( + rho: &DMatrix, + dims: (usize, usize), +) -> Result { + validate_density_matrix(rho)?; + let (dim_a, dim_b) = dims; + let Some(total_dim) = dim_a.checked_mul(dim_b) else { + return Err(MeasureError::InvalidSubsystemDimensions { + dims: vec![dim_a, dim_b], + matrix_dim: rho.nrows(), + }); + }; + if dim_a == 0 || dim_b == 0 || rho.nrows() != total_dim || rho.ncols() != total_dim { + return Err(MeasureError::InvalidSubsystemDimensions { + dims: vec![dim_a, dim_b], + matrix_dim: rho.nrows(), + }); + } + + let rho_a = partial_trace_subsystems(rho, &[dim_a, dim_b], &[1])?; + let rho_b = partial_trace_subsystems(rho, &[dim_a, dim_b], &[0])?; + Ok(entropy(&rho_a)? + entropy(&rho_b)? - entropy(rho)?) +} + fn validate_state_vector(vector: &DVector) -> Result<(), MeasureError> { let mut norm_sqr = 0.0; for value in vector.iter() { @@ -393,6 +663,129 @@ fn trace(matrix: &DMatrix) -> Complex64 { (0..n).map(|idx| matrix[(idx, idx)]).sum() } +fn pauli_y_tensor_pauli_y() -> DMatrix { + let i = Complex64::new(0.0, 1.0); + let minus_i = Complex64::new(0.0, -1.0); + let y = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(0.0, 0.0), + minus_i, + i, + Complex64::new(0.0, 0.0), + ], + ); + kronecker(&y, &y) +} + +fn kronecker(left: &DMatrix, right: &DMatrix) -> DMatrix { + let rows = left.nrows() * right.nrows(); + let cols = left.ncols() * right.ncols(); + let mut out = DMatrix::zeros(rows, cols); + for left_row in 0..left.nrows() { + for left_col in 0..left.ncols() { + let scale = left[(left_row, left_col)]; + for right_row in 0..right.nrows() { + for right_col in 0..right.ncols() { + out[( + left_row * right.nrows() + right_row, + left_col * right.ncols() + right_col, + )] = scale * right[(right_row, right_col)]; + } + } + } + } + out +} + +fn validate_subsystem_dimensions( + rho: &DMatrix, + dims: &[usize], +) -> Result<(), MeasureError> { + let Some(total_dim) = + dims.iter().try_fold( + 1usize, + |acc, &dim| { + if dim == 0 { None } else { acc.checked_mul(dim) } + }, + ) + else { + return Err(MeasureError::InvalidSubsystemDimensions { + dims: dims.to_vec(), + matrix_dim: rho.nrows(), + }); + }; + + if rho.nrows() == total_dim && rho.ncols() == total_dim { + Ok(()) + } else { + Err(MeasureError::InvalidSubsystemDimensions { + dims: dims.to_vec(), + matrix_dim: rho.nrows(), + }) + } +} + +fn subsystem_product(dims: &[usize], subsystems: &[usize]) -> Result { + subsystems.iter().try_fold(1usize, |acc, &subsystem| { + acc.checked_mul(dims[subsystem]) + .ok_or_else(|| MeasureError::InvalidSubsystemDimensions { + dims: dims.to_vec(), + matrix_dim: usize::MAX, + }) + }) +} + +fn subsystem_strides(dims: &[usize]) -> Result, MeasureError> { + let mut strides = Vec::with_capacity(dims.len()); + let mut stride = 1usize; + for &dim in dims { + strides.push(stride); + stride = + stride + .checked_mul(dim) + .ok_or_else(|| MeasureError::InvalidSubsystemDimensions { + dims: dims.to_vec(), + matrix_dim: usize::MAX, + })?; + } + Ok(strides) +} + +fn embed_subsystem_index( + dims: &[usize], + strides: &[usize], + kept_subsystems: &[usize], + kept_index: usize, + traced_subsystems: &[usize], + traced_index: usize, +) -> usize { + let mut index = 0usize; + let mut kept_remaining = kept_index; + for &subsystem in kept_subsystems { + let coord = kept_remaining % dims[subsystem]; + kept_remaining /= dims[subsystem]; + index += coord * strides[subsystem]; + } + let mut traced_remaining = traced_index; + for &subsystem in traced_subsystems { + let coord = traced_remaining % dims[subsystem]; + traced_remaining /= dims[subsystem]; + index += coord * strides[subsystem]; + } + index +} + +fn binary_entropy(probability: f64) -> f64 { + let p = probability.clamp(0.0, 1.0); + if p <= DEFAULT_TOLERANCE || (1.0 - p) <= DEFAULT_TOLERANCE { + 0.0 + } else { + -p * p.log2() - (1.0 - p) * (1.0 - p).log2() + } +} + fn hilbert_dim(num_qubits: usize) -> Result { 2usize .checked_pow( @@ -480,6 +873,104 @@ mod tests { )); } + #[test] + fn two_qubit_entanglement_measures_match_known_states() { + let bell = ket(&[ + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + ]); + let bell_rho = pure_density(&bell); + assert_close(concurrence(&bell_rho).unwrap(), 1.0); + assert_close(entanglement_of_formation(&bell_rho).unwrap(), 1.0); + assert_close(mutual_information(&bell_rho, (2, 2)).unwrap(), 2.0); + + let zero_zero = ket(&[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + ]); + let product = pure_density(&zero_zero); + assert_close(concurrence(&product).unwrap(), 0.0); + assert_close(entanglement_of_formation(&product).unwrap(), 0.0); + assert_close(mutual_information(&product, (2, 2)).unwrap(), 0.0); + } + + #[test] + fn mutual_information_accepts_non_qubit_subsystem_dims() { + let mut rho = DMatrix::zeros(6, 6); + rho[(0, 0)] = Complex64::new(0.5, 0.0); + rho[(5, 5)] = Complex64::new(0.5, 0.0); + + assert_close(mutual_information(&rho, (2, 3)).unwrap(), 1.0); + } + + #[test] + fn partial_trace_supports_method_and_qubit_forms() { + let bell = ket(&[ + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + ]); + let bell_rho = pure_density(&bell); + + let reduced_from_method = bell_rho.partial_trace(&[2, 2], &[1]).unwrap(); + let reduced_from_qubits = partial_trace_qubits(&bell_rho, 2, &[1]).unwrap(); + let expected = DMatrix::from_diagonal_element(2, 2, Complex64::new(0.5, 0.0)); + + assert_close((&reduced_from_method - &expected).norm(), 0.0); + assert_close((&reduced_from_qubits - expected).norm(), 0.0); + } + + #[test] + fn partial_trace_subsystems_accepts_arbitrary_tensor_factors() { + let mut state = DVector::zeros(12); + state[2] = Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0); + state[9] = Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0); + let rho = pure_density(&state); + + let reduced = partial_trace_subsystems(&rho, &[2, 3, 2], &[1]).unwrap(); + let mut expected = DMatrix::zeros(4, 4); + expected[(0, 0)] = Complex64::new(0.5, 0.0); + expected[(0, 3)] = Complex64::new(0.5, 0.0); + expected[(3, 0)] = Complex64::new(0.5, 0.0); + expected[(3, 3)] = Complex64::new(0.5, 0.0); + + assert_close((reduced - expected).norm(), 0.0); + } + + #[test] + fn partial_trace_rejects_repeated_or_out_of_range_subsystems() { + let mixed = DMatrix::from_diagonal_element(4, 4, Complex64::new(0.25, 0.0)); + assert!(matches!( + partial_trace_subsystems(&mixed, &[2, 2], &[0, 0]).unwrap_err(), + MeasureError::DuplicateSubsystem { subsystem: 0 } + )); + assert!(matches!( + partial_trace_subsystems(&mixed, &[2, 2], &[2]).unwrap_err(), + MeasureError::SubsystemOutOfRange { + num_subsystems: 2, + subsystem: 2 + } + )); + } + + #[test] + fn entanglement_measures_reject_invalid_shapes() { + let mixed = DMatrix::from_diagonal_element(2, 2, Complex64::new(0.5, 0.0)); + assert!(matches!( + concurrence(&mixed).unwrap_err(), + MeasureError::InvalidMatrixShape { .. } + )); + assert!(matches!( + mutual_information(&mixed, (2, 2)).unwrap_err(), + MeasureError::InvalidSubsystemDimensions { .. } + )); + } + #[test] fn process_and_average_gate_fidelity_match_depolarizing_channel() { let identity = Ptm::identity(1).unwrap(); From 0a9bb445e59a4b7a9415a5cae0ae5bb0c81f4ec5 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 22:01:53 -0600 Subject: [PATCH 072/125] Add packed Pauli commutation matrix --- crates/pecos-quantum/src/pauli_group.rs | 19 +++-- crates/pecos-quantum/src/pauli_sequence.rs | 85 +++++++++++++++---- crates/pecos-quantum/src/stabilizer_group.rs | 19 ++++- docs/user-guide/python-pauli-qec.md | 2 +- .../src/pauli_sequence_bindings.rs | 6 +- 5 files changed, 101 insertions(+), 30 deletions(-) diff --git a/crates/pecos-quantum/src/pauli_group.rs b/crates/pecos-quantum/src/pauli_group.rs index fe3889452..e3e471f51 100644 --- a/crates/pecos-quantum/src/pauli_group.rs +++ b/crates/pecos-quantum/src/pauli_group.rs @@ -453,9 +453,11 @@ impl PauliGroup { self.inner.to_symplectic_matrix() } - /// Returns the commutation matrix (always all-true for a valid group). + /// Returns the pairwise anticommutation matrix. + /// + /// This is always all-zero for a valid commuting group. #[must_use] - pub fn commutation_matrix(&self) -> Vec> { + pub fn commutation_matrix(&self) -> F2Matrix { self.inner.commutation_matrix() } @@ -1164,14 +1166,15 @@ mod tests { // --- commutation_matrix for valid group --- #[test] - fn commutation_matrix_all_true() { + fn commutation_matrix_all_zero() { let group = PauliGroup::new(vec![X(0), Z(1), X(2)]).unwrap(); let mat = group.commutation_matrix(); - for row in &mat { - for &val in row { - assert!( - val, - "commutation matrix should be all-true for abelian group" + for row in 0..mat.num_rows() { + for col in 0..mat.num_cols() { + assert_eq!( + mat.get(row, col), + 0, + "anticommutation matrix should be all-zero for abelian group" ); } } diff --git a/crates/pecos-quantum/src/pauli_sequence.rs b/crates/pecos-quantum/src/pauli_sequence.rs index c0b35fc84..66510557f 100644 --- a/crates/pecos-quantum/src/pauli_sequence.rs +++ b/crates/pecos-quantum/src/pauli_sequence.rs @@ -795,20 +795,22 @@ impl PauliSequence { true } - /// Returns the commutation matrix. + /// Returns the pairwise anticommutation matrix. /// - /// `result[i][j]` is `true` if entries `i` and `j` commute, `false` if they anticommute. - /// The diagonal is always `true` (every operator commutes with itself). + /// Entry `(i, j)` is `1` if entries `i` and `j` anticommute, and `0` if + /// they commute. The diagonal is always zero. #[must_use] - #[allow(clippy::needless_range_loop)] // symmetric update requires indexing both [i][j] and [j][i] - pub fn commutation_matrix(&self) -> Vec> { + pub fn commutation_matrix(&self) -> F2Matrix { let k = self.paulis.len(); - let mut matrix = vec![vec![true; k]; k]; + let n = self.num_qubits(); + let (x_rows, z_rows) = self.to_packed_xz_rows(n); + let mut matrix = F2Matrix::zeros(k, k); for i in 0..k { for j in (i + 1)..k { - let commutes = self.paulis[i].commutes_with(&self.paulis[j]); - matrix[i][j] = commutes; - matrix[j][i] = commutes; + if symplectic_inner_product(&x_rows[i], &z_rows[i], &x_rows[j], &z_rows[j]) != 0 { + matrix.set(i, j, 1); + matrix.set(j, i, 1); + } } } matrix @@ -916,6 +918,35 @@ impl PauliSequence { s_omega.kernel() } + + fn to_packed_xz_rows(&self, num_qubits: usize) -> (Vec>, Vec>) { + let num_words = num_qubits.div_ceil(F2Matrix::WORD_BITS); + let mut x_rows = vec![vec![0u64; num_words]; self.paulis.len()]; + let mut z_rows = vec![vec![0u64; num_words]; self.paulis.len()]; + for (row, pauli) in self.paulis.iter().enumerate() { + for q in pauli.x_positions() { + if q < num_qubits { + let (word, mask) = F2Matrix::word_mask(q); + x_rows[row][word] |= mask; + } + } + for q in pauli.z_positions() { + if q < num_qubits { + let (word, mask) = F2Matrix::word_mask(q); + z_rows[row][word] |= mask; + } + } + } + (x_rows, z_rows) + } +} + +fn symplectic_inner_product(x_a: &[u64], z_a: &[u64], x_b: &[u64], z_b: &[u64]) -> u8 { + let mut parity = 0u32; + for (((&xa, &za), &xb), &zb) in x_a.iter().zip(z_a).zip(x_b).zip(z_b) { + parity ^= ((xa & zb) ^ (za & xb)).count_ones() & 1; + } + u8::from(parity != 0) } impl PauliSequence { @@ -1127,16 +1158,38 @@ mod tests { let gens = PauliSequence::new(vec![X(0), Z(0), Y(0)]); let cm = gens.commutation_matrix(); // X,Z anticommute - assert!(!cm[0][1]); - assert!(!cm[1][0]); + assert_eq!(cm.get(0, 1), 1); + assert_eq!(cm.get(1, 0), 1); // X,Y anticommute - assert!(!cm[0][2]); + assert_eq!(cm.get(0, 2), 1); // Z,Y anticommute - assert!(!cm[1][2]); + assert_eq!(cm.get(1, 2), 1); // Self-commutation - assert!(cm[0][0]); - assert!(cm[1][1]); - assert!(cm[2][2]); + assert_eq!(cm.get(0, 0), 0); + assert_eq!(cm.get(1, 1), 0); + assert_eq!(cm.get(2, 2), 0); + } + + #[test] + fn test_commutation_matrix_matches_pairwise_across_packed_words() { + let gens = PauliSequence::new(vec![ + X(0), + Z(0), + X(65) & Z(130), + Z(65), + Y(130), + Zs([0, 65, 130]), + ]); + let cm = gens.commutation_matrix(); + + assert_eq!(cm.num_rows(), gens.len()); + assert_eq!(cm.num_cols(), gens.len()); + for i in 0..gens.len() { + for j in 0..gens.len() { + let expected = u8::from(!gens.paulis()[i].commutes_with(&gens.paulis()[j])); + assert_eq!(cm.get(i, j), expected, "entry ({i}, {j})"); + } + } } #[test] diff --git a/crates/pecos-quantum/src/stabilizer_group.rs b/crates/pecos-quantum/src/stabilizer_group.rs index dea18b3a1..c62206153 100644 --- a/crates/pecos-quantum/src/stabilizer_group.rs +++ b/crates/pecos-quantum/src/stabilizer_group.rs @@ -332,9 +332,11 @@ impl PauliStabilizerGroup { self.inner.to_symplectic_matrix() } - /// Returns the commutation matrix (always all-true for a valid stabilizer group). + /// Returns the pairwise anticommutation matrix. + /// + /// This is always all-zero for a valid stabilizer group. #[must_use] - pub fn commutation_matrix(&self) -> Vec> { + pub fn commutation_matrix(&self) -> F2Matrix { self.inner.commutation_matrix() } @@ -1042,6 +1044,19 @@ mod tests { } } + #[test] + fn commutation_matrix_delegates_as_all_zero_anticommutation_matrix() { + let stab = PauliStabilizerGroup::new(vec![Zs([0, 1]), Zs([1, 2])]).unwrap(); + let mat = stab.commutation_matrix(); + assert_eq!(mat.num_rows(), 2); + assert_eq!(mat.num_cols(), 2); + for row in 0..mat.num_rows() { + for col in 0..mat.num_cols() { + assert_eq!(mat.get(row, col), 0); + } + } + } + // ======================================================================== // as_group() accessor // ======================================================================== diff --git a/docs/user-guide/python-pauli-qec.md b/docs/user-guide/python-pauli-qec.md index b0c72ecfd..3d0d31edc 100644 --- a/docs/user-guide/python-pauli-qec.md +++ b/docs/user-guide/python-pauli-qec.md @@ -156,7 +156,7 @@ print(seq.is_abelian()) # False (XZ and ZX anticommute) # Commutation matrix comm = seq.commutation_matrix() -# comm[i][j] is True if seq[i] commutes with seq[j] +# comm[i][j] is 1 if seq[i] anticommutes with seq[j] # GF(2) membership print(seq.contains(PauliString.from_str("YY"))) # True (XZ * ZX = -YY in GF(2) span) diff --git a/python/pecos-rslib/src/pauli_sequence_bindings.rs b/python/pecos-rslib/src/pauli_sequence_bindings.rs index 4fad77cee..e08cfe5ff 100644 --- a/python/pecos-rslib/src/pauli_sequence_bindings.rs +++ b/python/pecos-rslib/src/pauli_sequence_bindings.rs @@ -126,9 +126,9 @@ impl PyPauliSequence { self.inner.is_abelian() } - /// Commutation matrix: result[i][j] is True if i and j commute. - fn commutation_matrix(&self) -> Vec> { - self.inner.commutation_matrix() + /// Anticommutation matrix: result[i][j] is 1 if i and j anticommute. + fn commutation_matrix(&self) -> Vec> { + self.inner.commutation_matrix().rows() } /// Row-reduced form: independent Pauli strings in echelon form. From 38b5f8649bac319381cf611a18da96e4ba2999c5 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 22:17:09 -0600 Subject: [PATCH 073/125] Add Choi tomography helpers --- crates/pecos-quantum/src/channel.rs | 162 +++++++++++++++++++++++++--- 1 file changed, 150 insertions(+), 12 deletions(-) diff --git a/crates/pecos-quantum/src/channel.rs b/crates/pecos-quantum/src/channel.rs index d422e7749..39ebb949d 100644 --- a/crates/pecos-quantum/src/channel.rs +++ b/crates/pecos-quantum/src/channel.rs @@ -1519,18 +1519,16 @@ impl ChoiMatrix { Ok(out) } - /// Returns whether `Tr_output(J) = I_input` within the default tolerance. - #[must_use] - pub fn is_trace_preserving(&self) -> bool { - self.is_trace_preserving_with_tolerance(1e-10) - } - - /// Returns whether `Tr_output(J) = I_input` within `tolerance`. - #[must_use] - pub fn is_trace_preserving_with_tolerance(&self, tolerance: f64) -> bool { - let Ok(dim) = hilbert_dim(self.num_qubits) else { - return false; - }; + /// Returns the output partial trace `Tr_output(J)`. + /// + /// With PECOS's column-stacked Choi convention, this equals the input-space + /// identity for a trace-preserving channel. + /// + /// # Errors + /// + /// Returns an error when the Hilbert-space dimension overflows. + pub fn partial_trace_output(&self) -> Result, ChannelError> { + let dim = hilbert_dim(self.num_qubits)?; let mut reduced = DMatrix::zeros(dim, dim); for input_row in 0..dim { for input_col in 0..dim { @@ -1544,6 +1542,98 @@ impl ChoiMatrix { reduced[(input_row, input_col)] = value; } } + Ok(reduced) + } + + /// Returns the input partial trace `Tr_input(J)`. + /// + /// With PECOS's column-stacked Choi convention, this equals `E(I)` and + /// therefore equals the output-space identity for a unital channel. + /// + /// # Errors + /// + /// Returns an error when the Hilbert-space dimension overflows. + pub fn partial_trace_input(&self) -> Result, ChannelError> { + let dim = hilbert_dim(self.num_qubits)?; + let mut reduced = DMatrix::zeros(dim, dim); + for output_row in 0..dim { + for output_col in 0..dim { + let mut value = Complex64::new(0.0, 0.0); + for input in 0..dim { + value += self.matrix[( + choi_index(dim, output_row, input), + choi_index(dim, output_col, input), + )]; + } + reduced[(output_row, output_col)] = value; + } + } + Ok(reduced) + } + + /// Returns whether this Choi matrix is positive semidefinite within the + /// default tolerance. + #[must_use] + pub fn is_completely_positive(&self) -> bool { + self.is_completely_positive_with_tolerance(1e-10) + } + + /// Returns whether this Choi matrix is positive semidefinite within + /// `tolerance`. + #[must_use] + pub fn is_completely_positive_with_tolerance(&self, tolerance: f64) -> bool { + self.to_kraus_with_tolerance(tolerance).is_ok() + } + + /// Returns whether this Choi matrix is completely positive and + /// trace-preserving within the default tolerance. + #[must_use] + pub fn is_cptp(&self) -> bool { + self.is_cptp_with_tolerance(1e-10) + } + + /// Returns whether this Choi matrix is completely positive and + /// trace-preserving within `tolerance`. + #[must_use] + pub fn is_cptp_with_tolerance(&self, tolerance: f64) -> bool { + self.is_completely_positive_with_tolerance(tolerance) + && self.is_trace_preserving_with_tolerance(tolerance) + } + + /// Returns whether `E(I) = I` within the default tolerance. + #[must_use] + pub fn is_unital(&self) -> bool { + self.is_unital_with_tolerance(1e-10) + } + + /// Returns whether `E(I) = I` within `tolerance`. + #[must_use] + pub fn is_unital_with_tolerance(&self, tolerance: f64) -> bool { + let Ok(dim) = hilbert_dim(self.num_qubits) else { + return false; + }; + let Ok(reduced) = self.partial_trace_input() else { + return false; + }; + let identity = DMatrix::::identity(dim, dim); + matrix_max_abs_diff(&reduced, &identity) <= tolerance + } + + /// Returns whether `Tr_output(J) = I_input` within the default tolerance. + #[must_use] + pub fn is_trace_preserving(&self) -> bool { + self.is_trace_preserving_with_tolerance(1e-10) + } + + /// Returns whether `Tr_output(J) = I_input` within `tolerance`. + #[must_use] + pub fn is_trace_preserving_with_tolerance(&self, tolerance: f64) -> bool { + let Ok(dim) = hilbert_dim(self.num_qubits) else { + return false; + }; + let Ok(reduced) = self.partial_trace_output() else { + return false; + }; let identity = DMatrix::::identity(dim, dim); matrix_max_abs_diff(&reduced, &identity) <= tolerance } @@ -2510,6 +2600,9 @@ mod tests { assert_eq!(choi.num_qubits(), 1); assert_eq!(choi.matrix().shape(), (4, 4)); assert!(choi.is_trace_preserving()); + assert!(choi.is_completely_positive()); + assert!(choi.is_cptp()); + assert!(choi.is_unital()); assert_complex_close(trace_complex(choi.matrix()), Complex64::new(2.0, 0.0)); let mut expected = DMatrix::zeros(4, 4); @@ -2518,6 +2611,51 @@ mod tests { expected[(3, 0)] = Complex64::new(1.0, 0.0); expected[(3, 3)] = Complex64::new(1.0, 0.0); assert_complex_matrix_close(choi.matrix(), &expected); + + let identity = DMatrix::identity(2, 2); + assert_complex_matrix_close(&choi.partial_trace_output().unwrap(), &identity); + assert_complex_matrix_close(&choi.partial_trace_input().unwrap(), &identity); + } + + #[test] + fn choi_tomography_helpers_classify_basic_channels() { + let zero = ChoiMatrix::try_new(1, DMatrix::zeros(4, 4)).unwrap(); + assert!(zero.is_completely_positive()); + assert!(!zero.is_trace_preserving()); + assert!(!zero.is_cptp()); + assert!(!zero.is_unital()); + + let Op::Channel(expr) = op::AmplitudeDamping(0.25, 0) else { + panic!("expected channel"); + }; + let damping = ChoiMatrix::from_channel_expr(&expr).unwrap(); + assert!(damping.is_completely_positive()); + assert!(damping.is_trace_preserving()); + assert!(damping.is_cptp()); + assert!(!damping.is_unital()); + + let mut expected_trace_input = DMatrix::zeros(2, 2); + expected_trace_input[(0, 0)] = Complex64::new(1.25, 0.0); + expected_trace_input[(1, 1)] = Complex64::new(0.75, 0.0); + assert_complex_matrix_close( + &damping.partial_trace_input().unwrap(), + &expected_trace_input, + ); + } + + #[test] + fn choi_transpose_map_is_trace_preserving_unital_but_not_cp() { + let mut transpose_choi = DMatrix::zeros(4, 4); + transpose_choi[(0, 0)] = Complex64::new(1.0, 0.0); + transpose_choi[(1, 2)] = Complex64::new(1.0, 0.0); + transpose_choi[(2, 1)] = Complex64::new(1.0, 0.0); + transpose_choi[(3, 3)] = Complex64::new(1.0, 0.0); + let choi = ChoiMatrix::try_new(1, transpose_choi).unwrap(); + + assert!(choi.is_trace_preserving()); + assert!(choi.is_unital()); + assert!(!choi.is_completely_positive()); + assert!(!choi.is_cptp()); } #[test] From 7afb9b37b355df187134f77c61fe7d6da526fdc2 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 22:39:29 -0600 Subject: [PATCH 074/125] Add tomography and GPU state access helpers --- crates/pecos-gpu-sims/src/lib.rs | 2 + crates/pecos-gpu-sims/src/state_access.rs | 177 +++++++++++ crates/pecos-quantum/src/channel.rs | 142 +++++++++ crates/pecos-quantum/src/diamond_norm.rs | 348 +++++++++++++++++++++ crates/pecos-quantum/src/lib.rs | 10 +- crates/pecos-quantum/src/measures.rs | 4 +- crates/pecos-quantum/src/pauli_sequence.rs | 4 +- 7 files changed, 681 insertions(+), 6 deletions(-) create mode 100644 crates/pecos-gpu-sims/src/state_access.rs create mode 100644 crates/pecos-quantum/src/diamond_norm.rs diff --git a/crates/pecos-gpu-sims/src/lib.rs b/crates/pecos-gpu-sims/src/lib.rs index d54c7eeb7..126ac27bf 100644 --- a/crates/pecos-gpu-sims/src/lib.rs +++ b/crates/pecos-gpu-sims/src/lib.rs @@ -48,6 +48,7 @@ mod gpu_sampler; mod gpu_stab; mod gpu_stab_multi; pub mod prelude; +pub mod state_access; #[cfg(test)] mod gpu_sampler_validation; @@ -75,6 +76,7 @@ pub use gpu_pauli_prop::GpuPauliProp; pub use gpu_sampler::{GpuMeasurementSampler, GpuSampleResult}; pub use gpu_stab::GpuStab; pub use gpu_stab_multi::GpuStabMulti; +pub use state_access::{GpuDensityMatrixHostAccess, GpuStateVectorHostAccess}; /// Default GPU stabilizer simulator using `PecosRng` pub type DefaultGpuStab = GpuStab; diff --git a/crates/pecos-gpu-sims/src/state_access.rs b/crates/pecos-gpu-sims/src/state_access.rs new file mode 100644 index 000000000..95dd7f032 --- /dev/null +++ b/crates/pecos-gpu-sims/src/state_access.rs @@ -0,0 +1,177 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Explicit host-snapshot state access for GPU-backed simulators. +//! +//! The generic `pecos_simulators::StateVectorAccess` and +//! `DensityMatrixAccess` traits look like ordinary passive inspection. For GPU +//! simulators, inspection requires synchronization and device-to-host copy. The +//! traits in this module make that transfer explicit in the method names while +//! returning the same little-endian data shapes as the CPU state-access traits. + +use num_complex::Complex64; +use pecos_simulators::{QuantumSimulator, StateAccessError}; + +use crate::{GpuDensityMatrix, GpuStateVec32, GpuStateVec64, GpuStateVecBackend}; + +/// Explicit host readback for GPU state-vector simulators. +pub trait GpuStateVectorHostAccess { + /// Returns the number of qubits represented by the device state. + fn num_qubits(&self) -> usize; + + /// Synchronizes pending GPU work and returns a host-owned state vector. + /// + /// The vector is in little-endian computational-basis order. Calling this + /// method performs a device-to-host transfer. + /// + /// # Errors + /// + /// Returns an error if the Hilbert-space dimension overflows. + fn state_vector_host_snapshot(&mut self) -> Result, StateAccessError>; + + /// Synchronizes pending GPU work and returns one host-copied amplitude. + /// + /// # Errors + /// + /// Returns an error if `basis_state` is outside the Hilbert space. + fn amplitude_host_snapshot( + &mut self, + basis_state: usize, + ) -> Result { + validate_basis_index(self.num_qubits(), basis_state)?; + Ok(self.state_vector_host_snapshot()?[basis_state]) + } +} + +/// Explicit host readback for GPU density-matrix simulators. +pub trait GpuDensityMatrixHostAccess { + /// Returns the number of physical qubits represented by the density matrix. + fn num_qubits(&self) -> usize; + + /// Synchronizes pending GPU work and returns a host-owned density matrix. + /// + /// The matrix is in little-endian computational-basis order. Calling this + /// method performs a device-to-host transfer and, for the current + /// Choi-state implementation, reconstructs the density matrix on the host. + /// + /// # Errors + /// + /// Returns an error if the Hilbert-space dimension overflows. + fn density_matrix_host_snapshot(&mut self) -> Result>, StateAccessError>; + + /// Synchronizes pending GPU work and returns one host-copied density-matrix + /// element. + /// + /// # Errors + /// + /// Returns an error if either basis index is outside the Hilbert space. + fn density_matrix_element_host_snapshot( + &mut self, + row: usize, + col: usize, + ) -> Result { + validate_basis_index(self.num_qubits(), row)?; + validate_basis_index(self.num_qubits(), col)?; + Ok(self.density_matrix_host_snapshot()?[row][col]) + } +} + +impl GpuStateVectorHostAccess for GpuStateVec32 { + fn num_qubits(&self) -> usize { + QuantumSimulator::num_qubits(self) + } + + fn state_vector_host_snapshot(&mut self) -> Result, StateAccessError> { + hilbert_dim(GpuStateVectorHostAccess::num_qubits(self))?; + Ok(self + .state() + .into_iter() + .map(|[re, im]| Complex64::new(f64::from(re), f64::from(im))) + .collect()) + } +} + +impl GpuStateVectorHostAccess for GpuStateVec64 { + fn num_qubits(&self) -> usize { + QuantumSimulator::num_qubits(self) + } + + fn state_vector_host_snapshot(&mut self) -> Result, StateAccessError> { + hilbert_dim(GpuStateVectorHostAccess::num_qubits(self))?; + Ok(self + .state() + .into_iter() + .map(|[re, im]| Complex64::new(re, im)) + .collect()) + } +} + +impl GpuDensityMatrixHostAccess for GpuDensityMatrix { + fn num_qubits(&self) -> usize { + self.num_qubits() + } + + fn density_matrix_host_snapshot(&mut self) -> Result>, StateAccessError> { + hilbert_dim(self.num_qubits())?; + Ok(self.get_density_matrix()) + } +} + +fn validate_basis_index(num_qubits: usize, index: usize) -> Result<(), StateAccessError> { + let dim = hilbert_dim(num_qubits)?; + if index >= dim { + return Err(StateAccessError::BasisIndexOutOfRange { + num_qubits, + dim, + index, + }); + } + Ok(()) +} + +fn hilbert_dim(num_qubits: usize) -> Result { + 2usize + .checked_pow( + num_qubits + .try_into() + .map_err(|_| StateAccessError::DimensionOverflow { num_qubits })?, + ) + .ok_or(StateAccessError::DimensionOverflow { num_qubits }) +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn validates_basis_indices_against_hilbert_dimension() { + assert_eq!(validate_basis_index(3, 7), Ok(())); + assert_eq!( + validate_basis_index(3, 8), + Err(StateAccessError::BasisIndexOutOfRange { + num_qubits: 3, + dim: 8, + index: 8, + }) + ); + } + + #[test] + fn reports_dimension_overflow() { + assert_eq!(hilbert_dim(0), Ok(1)); + assert_eq!(hilbert_dim(3), Ok(8)); + assert!(matches!( + hilbert_dim(usize::BITS as usize), + Err(StateAccessError::DimensionOverflow { .. }) + )); + } +} diff --git a/crates/pecos-quantum/src/channel.rs b/crates/pecos-quantum/src/channel.rs index 39ebb949d..7a2069876 100644 --- a/crates/pecos-quantum/src/channel.rs +++ b/crates/pecos-quantum/src/channel.rs @@ -140,6 +140,13 @@ pub enum ChannelError { /// Repeated qubit/subsystem index. qubit: usize, }, + /// A tomography reconstruction had the wrong number of basis samples. + InvalidTomographySampleCount { + /// Expected number of operator-basis outputs. + expected: usize, + /// Actual number of supplied outputs. + actual: usize, + }, } impl fmt::Display for ChannelError { @@ -196,6 +203,10 @@ impl fmt::Display for ChannelError { Self::DuplicateSubsystem { qubit } => { write!(f, "duplicate subsystem/qubit index: {qubit}") } + Self::InvalidTomographySampleCount { expected, actual } => write!( + f, + "invalid tomography sample count {actual}; expected {expected} operator-basis outputs" + ), } } } @@ -1399,6 +1410,49 @@ impl ChoiMatrix { Self::try_new(ptm.num_qubits, matrix) } + /// Reconstructs a Choi matrix from complete operator-basis tomography data. + /// + /// `outputs` must contain `d^2` matrices, where `d = 2^num_qubits`. + /// Entry `input_row + input_col * d` is the measured/reconstructed output + /// operator `E(|input_row>], + ) -> Result { + let dim = hilbert_dim(num_qubits)?; + let dim_squared = pauli_basis_len(num_qubits)?; + if outputs.len() != dim_squared { + return Err(ChannelError::InvalidTomographySampleCount { + expected: dim_squared, + actual: outputs.len(), + }); + } + + let mut matrix = DMatrix::zeros(dim_squared, dim_squared); + for input_col in 0..dim { + for input_row in 0..dim { + let output = &outputs[matrix_unit_index(dim, input_row, input_col)]; + validate_complex_matrix(output, dim, dim)?; + for output_row in 0..dim { + for output_col in 0..dim { + matrix[( + choi_index(dim, output_row, input_row), + choi_index(dim, output_col, input_col), + )] = output[(output_row, output_col)]; + } + } + } + } + Self::try_new(num_qubits, matrix) + } + /// Converts this Choi matrix to a dense PTM. /// /// # Errors @@ -1715,6 +1769,29 @@ pub fn partial_trace( Ok(out) } +/// Returns the computational matrix-unit operator basis. +/// +/// The returned vector has length `d^2`, where `d = 2^num_qubits`. Entry +/// `row + col * d` is the matrix unit `|row> Result>, ChannelError> { + let dim = hilbert_dim(num_qubits)?; + let dim_squared = pauli_basis_len(num_qubits)?; + let mut basis = Vec::with_capacity(dim_squared); + for col in 0..dim { + for row in 0..dim { + let mut matrix = DMatrix::zeros(dim, dim); + matrix[(row, col)] = Complex64::new(1.0, 0.0); + basis.push(matrix); + } + } + Ok(basis) +} + /// Samples a random `num_qubits`-qubit Pauli string. /// /// Each qubit independently receives one of `I, X, Y, Z` with equal @@ -1997,6 +2074,10 @@ fn choi_index(dim: usize, output_index: usize, input_index: usize) -> usize { output_index + input_index * dim } +fn matrix_unit_index(dim: usize, row: usize, col: usize) -> usize { + row + col * dim +} + fn trace_complex(matrix: &DMatrix) -> Complex64 { let n = matrix.nrows().min(matrix.ncols()); (0..n).map(|idx| matrix[(idx, idx)]).sum() @@ -2733,6 +2814,67 @@ mod tests { )); } + #[test] + fn matrix_unit_basis_uses_column_stacked_order() { + let basis = matrix_unit_basis(1).unwrap(); + assert_eq!(basis.len(), 4); + for (idx, (row, col)) in [(0, 0), (1, 0), (0, 1), (1, 1)].into_iter().enumerate() { + let mut expected = DMatrix::zeros(2, 2); + expected[(row, col)] = Complex64::new(1.0, 0.0); + assert_complex_matrix_close(&basis[idx], &expected); + } + } + + #[test] + fn choi_reconstructs_identity_from_matrix_unit_outputs() { + let inputs = matrix_unit_basis(1).unwrap(); + let reconstructed = ChoiMatrix::from_matrix_unit_outputs(1, &inputs).unwrap(); + let expected = ChoiMatrix::from_unitary(&unitary::I(0), 1).unwrap(); + + assert_complex_matrix_close(reconstructed.matrix(), expected.matrix()); + assert!(reconstructed.is_cptp()); + assert!(reconstructed.is_unital()); + } + + #[test] + fn choi_reconstructs_amplitude_damping_from_matrix_unit_outputs() { + let Op::Channel(expr) = op::AmplitudeDamping(0.25, 0) else { + panic!("expected channel"); + }; + let expected = ChoiMatrix::from_channel_expr(&expr).unwrap(); + let outputs: Vec> = matrix_unit_basis(1) + .unwrap() + .iter() + .map(|operator| expected.apply_to_operator(operator).unwrap()) + .collect(); + + let reconstructed = ChoiMatrix::from_matrix_unit_outputs(1, &outputs).unwrap(); + assert_complex_matrix_close(reconstructed.matrix(), expected.matrix()); + assert!(reconstructed.is_cptp()); + assert!(!reconstructed.is_unital()); + } + + #[test] + fn choi_tomography_rejects_bad_sample_count_and_shape() { + let err = ChoiMatrix::from_matrix_unit_outputs(1, &[]).unwrap_err(); + assert_eq!( + err, + ChannelError::InvalidTomographySampleCount { + expected: 4, + actual: 0 + } + ); + + let bad_outputs = vec![DMatrix::zeros(2, 2); 3] + .into_iter() + .chain(std::iter::once(DMatrix::zeros(3, 3))) + .collect::>(); + assert!(matches!( + ChoiMatrix::from_matrix_unit_outputs(1, &bad_outputs).unwrap_err(), + ChannelError::InvalidMatrixShape { .. } + )); + } + #[test] fn partial_trace_of_bell_state_is_maximally_mixed() { let half = Complex64::new(0.5, 0.0); diff --git a/crates/pecos-quantum/src/diamond_norm.rs b/crates/pecos-quantum/src/diamond_norm.rs new file mode 100644 index 000000000..167389186 --- /dev/null +++ b/crates/pecos-quantum/src/diamond_norm.rs @@ -0,0 +1,348 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Internal linear-algebra helpers for a future Rust diamond-norm solver. +//! +//! This module deliberately does not expose a public `diamond_norm` routine or +//! add an SDP solver dependency yet. It contains the convention-sensitive pieces +//! needed before a feature-gated conic-solver integration is reviewable: +//! Clarabel-style scaled triangular vectorization for real PSD cones and the +//! standard complex-Hermitian to real-symmetric embedding. + +use std::error::Error; +use std::fmt; + +use nalgebra::DMatrix; +use num_complex::Complex64; + +const DEFAULT_TOLERANCE: f64 = 1e-12; + +/// Error returned by diamond-norm linear-algebra helpers. +#[derive(Debug, Clone, PartialEq)] +pub enum DiamondNormError { + /// A matrix was not square. + NonSquareMatrix { + /// Row count. + rows: usize, + /// Column count. + cols: usize, + }, + /// A scaled-vector input had the wrong length for the requested matrix. + InvalidSvecLength { + /// Expected triangular-vector length. + expected: usize, + /// Actual length. + actual: usize, + }, + /// A matrix expected to be symmetric or Hermitian was not within tolerance. + NonHermitian { + /// Maximum observed entrywise difference from the adjoint/symmetric + /// counterpart. + max_difference: f64, + /// Allowed tolerance. + tolerance: f64, + }, + /// A matrix entry was not finite. + NonFiniteEntry, +} + +impl fmt::Display for DiamondNormError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + Self::NonSquareMatrix { rows, cols } => { + write!(f, "matrix must be square, got {rows}x{cols}") + } + Self::InvalidSvecLength { expected, actual } => write!( + f, + "invalid scaled-triangle vector length {actual}; expected {expected}" + ), + Self::NonHermitian { + max_difference, + tolerance, + } => write!( + f, + "matrix is not Hermitian/symmetric within tolerance {tolerance}; max difference {max_difference}" + ), + Self::NonFiniteEntry => write!(f, "matrix contains a non-finite entry"), + } + } +} + +impl Error for DiamondNormError {} + +/// Returns the length of the scaled upper-triangular vector for an `n x n` +/// symmetric matrix. +#[must_use] +pub const fn scaled_psd_triangle_len(n: usize) -> usize { + n * (n + 1) / 2 +} + +/// Converts a real symmetric matrix to Clarabel-style scaled upper-triangular +/// vector form. +/// +/// Diagonal entries are stored unchanged. Strict upper-triangular entries are +/// multiplied by `sqrt(2)`, preserving Frobenius inner products under vector +/// dot products. +/// +/// # Errors +/// +/// Returns an error when `matrix` is not square, contains non-finite values, or +/// is not symmetric within the default tolerance. +pub fn svec_real_symmetric(matrix: &DMatrix) -> Result, DiamondNormError> { + svec_real_symmetric_with_tolerance(matrix, DEFAULT_TOLERANCE) +} + +/// Converts a real symmetric matrix to scaled upper-triangular vector form +/// with explicit symmetry tolerance. +/// +/// # Errors +/// +/// Returns an error when `matrix` is not square, contains non-finite values, or +/// is not symmetric within `tolerance`. +pub fn svec_real_symmetric_with_tolerance( + matrix: &DMatrix, + tolerance: f64, +) -> Result, DiamondNormError> { + validate_real_symmetric(matrix, tolerance)?; + let n = matrix.nrows(); + let sqrt2 = 2.0_f64.sqrt(); + let mut out = Vec::with_capacity(scaled_psd_triangle_len(n)); + for col in 0..n { + for row in 0..=col { + let scale = if row == col { 1.0 } else { sqrt2 }; + out.push(matrix[(row, col)] * scale); + } + } + Ok(out) +} + +/// Converts Clarabel-style scaled upper-triangular vector form back to a real +/// symmetric matrix. +/// +/// # Errors +/// +/// Returns an error when `data.len()` is not `n * (n + 1) / 2` or a data entry +/// is not finite. +pub fn smat_real_symmetric(n: usize, data: &[f64]) -> Result, DiamondNormError> { + let expected = scaled_psd_triangle_len(n); + if data.len() != expected { + return Err(DiamondNormError::InvalidSvecLength { + expected, + actual: data.len(), + }); + } + let sqrt2 = 2.0_f64.sqrt(); + let mut out = DMatrix::zeros(n, n); + let mut idx = 0; + for col in 0..n { + for row in 0..=col { + let value = data[idx]; + if !value.is_finite() { + return Err(DiamondNormError::NonFiniteEntry); + } + let unscaled = if row == col { value } else { value / sqrt2 }; + out[(row, col)] = unscaled; + out[(col, row)] = unscaled; + idx += 1; + } + } + Ok(out) +} + +/// Embeds a complex Hermitian matrix `A = X + iY` as a real symmetric matrix: +/// +/// ```text +/// [ X -Y ] +/// [ Y X ] +/// ``` +/// +/// This embedding maps complex PSD constraints into real PSD constraints and is +/// the representation needed before modeling the diamond-norm SDP in a real +/// conic solver. +/// +/// # Errors +/// +/// Returns an error when `matrix` is not square, contains non-finite values, or +/// is not Hermitian within the default tolerance. +pub fn hermitian_to_real_symmetric( + matrix: &DMatrix, +) -> Result, DiamondNormError> { + hermitian_to_real_symmetric_with_tolerance(matrix, DEFAULT_TOLERANCE) +} + +/// Hermitian-to-real-symmetric embedding with explicit tolerance. +/// +/// # Errors +/// +/// Returns an error when `matrix` is not square, contains non-finite values, or +/// is not Hermitian within `tolerance`. +pub fn hermitian_to_real_symmetric_with_tolerance( + matrix: &DMatrix, + tolerance: f64, +) -> Result, DiamondNormError> { + validate_hermitian(matrix, tolerance)?; + let n = matrix.nrows(); + let mut out = DMatrix::zeros(2 * n, 2 * n); + for row in 0..n { + for col in 0..n { + let value = matrix[(row, col)]; + out[(row, col)] = value.re; + out[(row, col + n)] = -value.im; + out[(row + n, col)] = value.im; + out[(row + n, col + n)] = value.re; + } + } + Ok(out) +} + +fn validate_real_symmetric(matrix: &DMatrix, tolerance: f64) -> Result<(), DiamondNormError> { + if matrix.nrows() != matrix.ncols() { + return Err(DiamondNormError::NonSquareMatrix { + rows: matrix.nrows(), + cols: matrix.ncols(), + }); + } + let mut max_difference: f64 = 0.0; + for row in 0..matrix.nrows() { + for col in 0..matrix.ncols() { + let value = matrix[(row, col)]; + if !value.is_finite() { + return Err(DiamondNormError::NonFiniteEntry); + } + max_difference = max_difference.max((value - matrix[(col, row)]).abs()); + } + } + if max_difference > tolerance { + return Err(DiamondNormError::NonHermitian { + max_difference, + tolerance, + }); + } + Ok(()) +} + +fn validate_hermitian(matrix: &DMatrix, tolerance: f64) -> Result<(), DiamondNormError> { + if matrix.nrows() != matrix.ncols() { + return Err(DiamondNormError::NonSquareMatrix { + rows: matrix.nrows(), + cols: matrix.ncols(), + }); + } + let mut max_difference: f64 = 0.0; + for row in 0..matrix.nrows() { + for col in 0..matrix.ncols() { + let value = matrix[(row, col)]; + if !value.re.is_finite() || !value.im.is_finite() { + return Err(DiamondNormError::NonFiniteEntry); + } + max_difference = max_difference.max((value - matrix[(col, row)].conj()).norm()); + } + } + if max_difference > tolerance { + return Err(DiamondNormError::NonHermitian { + max_difference, + tolerance, + }); + } + Ok(()) +} + +#[cfg(test)] +mod tests { + use super::*; + + fn assert_close(left: f64, right: f64) { + assert!((left - right).abs() < 1e-12, "{left} != {right}"); + } + + fn frobenius_inner(left: &DMatrix, right: &DMatrix) -> f64 { + left.iter().zip(right.iter()).map(|(a, b)| a * b).sum() + } + + #[test] + fn scaled_triangle_round_trips_real_symmetric_matrix() { + let matrix = + DMatrix::from_row_slice(3, 3, &[1.0, 2.0, -3.0, 2.0, 5.0, 7.0, -3.0, 7.0, 11.0]); + let packed = svec_real_symmetric(&matrix).unwrap(); + assert_eq!(packed.len(), 6); + let recovered = smat_real_symmetric(3, &packed).unwrap(); + for row in 0..3 { + for col in 0..3 { + assert_close(recovered[(row, col)], matrix[(row, col)]); + } + } + } + + #[test] + fn scaled_triangle_preserves_frobenius_inner_product() { + let a = DMatrix::from_row_slice(2, 2, &[1.0, 3.0, 3.0, 2.0]); + let b = DMatrix::from_row_slice(2, 2, &[5.0, -7.0, -7.0, 11.0]); + let a_vec = svec_real_symmetric(&a).unwrap(); + let b_vec = svec_real_symmetric(&b).unwrap(); + let vector_inner: f64 = a_vec.iter().zip(b_vec.iter()).map(|(x, y)| x * y).sum(); + + assert_close(vector_inner, frobenius_inner(&a, &b)); + } + + #[test] + fn hermitian_embedding_is_real_symmetric_and_trace_scaled() { + let i = Complex64::new(0.0, 1.0); + let matrix = DMatrix::from_row_slice( + 2, + 2, + &[Complex64::new(2.0, 0.0), i, -i, Complex64::new(3.0, 0.0)], + ); + let embedded = hermitian_to_real_symmetric(&matrix).unwrap(); + + assert_eq!(embedded.shape(), (4, 4)); + for row in 0..4 { + for col in 0..4 { + assert_close(embedded[(row, col)], embedded[(col, row)]); + } + } + assert_close(embedded.trace(), 10.0); + } + + #[test] + fn helper_validation_rejects_invalid_inputs() { + assert!(matches!( + svec_real_symmetric(&DMatrix::zeros(2, 3)).unwrap_err(), + DiamondNormError::NonSquareMatrix { .. } + )); + + let nonsymmetric = DMatrix::from_row_slice(2, 2, &[1.0, 2.0, 3.0, 4.0]); + assert!(matches!( + svec_real_symmetric(&nonsymmetric).unwrap_err(), + DiamondNormError::NonHermitian { .. } + )); + + assert!(matches!( + smat_real_symmetric(3, &[1.0, 2.0]).unwrap_err(), + DiamondNormError::InvalidSvecLength { .. } + )); + + let nonhermitian = DMatrix::from_row_slice( + 2, + 2, + &[ + Complex64::new(1.0, 0.0), + Complex64::new(1.0, 1.0), + Complex64::new(1.0, 1.0), + Complex64::new(1.0, 0.0), + ], + ); + assert!(matches!( + hermitian_to_real_symmetric(&nonhermitian).unwrap_err(), + DiamondNormError::NonHermitian { .. } + )); + } +} diff --git a/crates/pecos-quantum/src/lib.rs b/crates/pecos-quantum/src/lib.rs index 146b557ab..3f7f5ebc3 100644 --- a/crates/pecos-quantum/src/lib.rs +++ b/crates/pecos-quantum/src/lib.rs @@ -67,6 +67,7 @@ pub mod channel; mod circuit; mod circuit_display; mod dag_circuit; +pub mod diamond_norm; pub mod measures; pub mod pass; pub mod pauli_group; @@ -103,8 +104,13 @@ pub use pecos_num::dag::DagWouldCycleError; pub use channel::{ ChannelError, ChoiMatrix, DiagonalPtm, KrausOps, PauliChannel, PauliSum, Ptm, PtmBasisOrder, basis_bitmask, basis_digit_to_pauli, basis_element, basis_index, basis_label, bitmask_label, - partial_trace, pauli_basis_len, pauli_string_to_bitmask, pauli_to_basis_digit, - random_1q_clifford, random_2q_clifford, random_clifford, random_pauli, + matrix_unit_basis, partial_trace, pauli_basis_len, pauli_string_to_bitmask, + pauli_to_basis_digit, random_1q_clifford, random_2q_clifford, random_clifford, random_pauli, +}; +pub use diamond_norm::{ + DiamondNormError, hermitian_to_real_symmetric, hermitian_to_real_symmetric_with_tolerance, + scaled_psd_triangle_len, smat_real_symmetric, svec_real_symmetric, + svec_real_symmetric_with_tolerance, }; pub use measures::{ DensityMatrixPartialTrace, MeasureError, average_gate_fidelity, concurrence, diff --git a/crates/pecos-quantum/src/measures.rs b/crates/pecos-quantum/src/measures.rs index 847aff6a4..1868f5073 100644 --- a/crates/pecos-quantum/src/measures.rs +++ b/crates/pecos-quantum/src/measures.rs @@ -458,7 +458,7 @@ pub fn concurrence(rho: &DMatrix) -> Result { .collect(); roots.sort_by(|a, b| b.total_cmp(a)); let value = roots[0] - roots[1] - roots[2] - roots[3]; - Ok(value.max(0.0).min(1.0)) + Ok(value.clamp(0.0, 1.0)) } /// Returns the two-qubit entanglement of formation. @@ -471,7 +471,7 @@ pub fn concurrence(rho: &DMatrix) -> Result { /// Returns an error when [`concurrence`] fails. pub fn entanglement_of_formation(rho: &DMatrix) -> Result { let concurrence = concurrence(rho)?; - let argument = (1.0 + (1.0 - concurrence * concurrence).max(0.0).sqrt()) / 2.0; + let argument = f64::midpoint(1.0, (1.0 - concurrence * concurrence).max(0.0).sqrt()); Ok(binary_entropy(argument)) } diff --git a/crates/pecos-quantum/src/pauli_sequence.rs b/crates/pecos-quantum/src/pauli_sequence.rs index 66510557f..dd9dd3d0f 100644 --- a/crates/pecos-quantum/src/pauli_sequence.rs +++ b/crates/pecos-quantum/src/pauli_sequence.rs @@ -83,8 +83,8 @@ impl F2Matrix { pub fn from_rows(rows: Vec>) -> Self { let num_cols = rows.first().map_or(0, Vec::len); let mut mat = Self::zeros(rows.len(), num_cols); - for (i, row) in rows.iter().enumerate() { - mat.set_row(i, row); + for (i, row) in rows.into_iter().enumerate() { + mat.set_row(i, &row); } mat } From eb3942f4500ed1ca887cf094d5e58eb3b231fb17 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 23:46:16 -0600 Subject: [PATCH 075/125] Add random density matrix and channel generators --- crates/pecos-quantum/src/channel.rs | 174 ++++++++++++++++++++++++++++ crates/pecos-quantum/src/lib.rs | 3 +- 2 files changed, 176 insertions(+), 1 deletion(-) diff --git a/crates/pecos-quantum/src/channel.rs b/crates/pecos-quantum/src/channel.rs index 7a2069876..4aa0923cb 100644 --- a/crates/pecos-quantum/src/channel.rs +++ b/crates/pecos-quantum/src/channel.rs @@ -28,6 +28,7 @@ use std::collections::{BTreeMap, BTreeSet}; use std::error::Error; +use std::f64::consts::TAU; use std::fmt; use std::ops::{Add, Mul}; @@ -1792,6 +1793,107 @@ pub fn matrix_unit_basis(num_qubits: usize) -> Result>, C Ok(basis) } +/// Samples a Hilbert-Schmidt random density matrix on `num_qubits` qubits. +/// +/// This samples a square complex Ginibre matrix `G` and returns +/// `G G† / Tr(G G†)`. The returned matrix uses the same little-endian +/// computational-basis order as PECOS's dense matrix helpers. +/// +/// # Errors +/// +/// Returns an error when the Hilbert-space dimension overflows. +pub fn random_density_matrix( + rng: &mut R, + num_qubits: usize, +) -> Result, ChannelError> +where + R: Rng + ?Sized, +{ + let dim = hilbert_dim(num_qubits)?; + random_density_matrix_with_rank(rng, num_qubits, dim) +} + +/// Samples a Hilbert-Schmidt random density matrix with explicit Ginibre rank. +/// +/// A rank of `1` produces a random pure-state density matrix. Larger ranks +/// produce mixed states from a `dim x rank` complex Ginibre matrix. +/// +/// # Errors +/// +/// Returns an error when the Hilbert-space dimension overflows or `rank == 0`. +pub fn random_density_matrix_with_rank( + rng: &mut R, + num_qubits: usize, + rank: usize, +) -> Result, ChannelError> +where + R: Rng + ?Sized, +{ + if rank == 0 { + return Err(ChannelError::EmptyKrausSet); + } + let dim = hilbert_dim(num_qubits)?; + let ginibre = DMatrix::from_fn(dim, rank, |_, _| standard_complex_normal(rng)); + let mut rho = &ginibre * ginibre.adjoint(); + let trace = trace_complex(&rho).re; + if trace <= 0.0 || !trace.is_finite() { + return Err(ChannelError::DecompositionFailed { + reason: "random density matrix has invalid trace".to_string(), + }); + } + rho /= Complex64::new(trace, 0.0); + Ok(rho) +} + +/// Samples a random CPTP quantum channel in Kraus form. +/// +/// The implementation samples a random Stinespring isometry by QR-decomposing a +/// complex Ginibre matrix of shape `(num_kraus * d) x d`, where +/// `d = 2^num_qubits`, then splits the isometry into `num_kraus` Kraus blocks. +/// The resulting operators satisfy `sum_k K_k† K_k = I` up to numerical +/// precision. +/// +/// # Errors +/// +/// Returns an error when dimensions overflow or `num_kraus == 0`. +pub fn random_quantum_channel( + rng: &mut R, + num_qubits: usize, + num_kraus: usize, +) -> Result +where + R: Rng + ?Sized, +{ + if num_kraus == 0 { + return Err(ChannelError::EmptyKrausSet); + } + let dim = hilbert_dim(num_qubits)?; + let rows = dim + .checked_mul(num_kraus) + .ok_or(ChannelError::DimensionOverflow { num_qubits })?; + let ginibre = DMatrix::from_fn(rows, dim, |_, _| standard_complex_normal(rng)); + let (mut q, r) = ginibre.qr().unpack(); + + for col in 0..dim { + let diagonal = r[(col, col)]; + let norm = diagonal.norm(); + if norm > 0.0 { + let phase = diagonal / norm; + for row in 0..rows { + q[(row, col)] *= phase; + } + } + } + + let operators = (0..num_kraus) + .map(|kraus_idx| { + let start = kraus_idx * dim; + DMatrix::from_fn(dim, dim, |row, col| q[(start + row, col)]) + }) + .collect(); + KrausOps::try_new(num_qubits, operators) +} + /// Samples a random `num_qubits`-qubit Pauli string. /// /// Each qubit independently receives one of `I, X, Y, Z` with equal @@ -1827,6 +1929,20 @@ pub fn random_clifford(rng: &mut R) -> Clifford { all[rng.random_range(0..all.len())] } +fn standard_complex_normal(rng: &mut R) -> Complex64 { + Complex64::new(standard_normal(rng), standard_normal(rng)) +} + +fn standard_normal(rng: &mut R) -> f64 { + loop { + let u1 = rng.random::(); + if u1 > 0.0 { + let u2 = rng.random::(); + return (-2.0 * u1.ln()).sqrt() * (TAU * u2).cos(); + } + } +} + fn bitmask_from_paulis(paulis: &[Pauli]) -> PauliBitmaskSmall { let mut out = PauliBitmaskSmall::identity(); for (qubit, pauli) in paulis.iter().copied().enumerate() { @@ -2906,6 +3022,64 @@ mod tests { assert_complex_close(keep_q1[(1, 1)], Complex64::new(0.0, 0.0)); } + #[test] + fn random_density_matrix_is_normalized_hermitian_and_reproducible() { + let mut rng = PecosRng::seed_from_u64(123); + let rho = random_density_matrix(&mut rng, 2).unwrap(); + assert_eq!(rho.shape(), (4, 4)); + assert_complex_close(trace_complex(&rho), Complex64::new(1.0, 0.0)); + assert_complex_matrix_close(&rho, &rho.adjoint()); + + let mut same_seed = PecosRng::seed_from_u64(123); + let same = random_density_matrix(&mut same_seed, 2).unwrap(); + assert_complex_matrix_close(&rho, &same); + + let mut different_seed = PecosRng::seed_from_u64(456); + let different = random_density_matrix(&mut different_seed, 2).unwrap(); + assert_ne!(rho, different); + } + + #[test] + fn random_density_matrix_rank_one_is_pure() { + let mut rng = PecosRng::seed_from_u64(123); + let rho = random_density_matrix_with_rank(&mut rng, 2, 1).unwrap(); + let purity = trace_complex(&(&rho * &rho)).re; + assert_close(purity, 1.0); + + assert!(matches!( + random_density_matrix_with_rank(&mut rng, 1, 0).unwrap_err(), + ChannelError::EmptyKrausSet + )); + } + + #[test] + fn random_quantum_channel_is_cptp_and_reproducible() { + let mut rng = PecosRng::seed_from_u64(123); + let channel = random_quantum_channel(&mut rng, 1, 3).unwrap(); + assert_eq!(channel.operators().len(), 3); + assert!(channel.is_trace_preserving()); + assert!(channel.to_choi().unwrap().is_cptp()); + + let mut same_seed = PecosRng::seed_from_u64(123); + let same = random_quantum_channel(&mut same_seed, 1, 3).unwrap(); + for (left, right) in channel.operators().iter().zip(same.operators()) { + assert_complex_matrix_close(left, right); + } + + let mut different_seed = PecosRng::seed_from_u64(456); + let different = random_quantum_channel(&mut different_seed, 1, 3).unwrap(); + assert_ne!(channel, different); + } + + #[test] + fn random_quantum_channel_rejects_zero_kraus_count() { + let mut rng = PecosRng::seed_from_u64(123); + assert!(matches!( + random_quantum_channel(&mut rng, 1, 0).unwrap_err(), + ChannelError::EmptyKrausSet + )); + } + #[test] fn random_helpers_return_values_from_expected_sets() { let mut rng = PecosRng::seed_from_u64(123); diff --git a/crates/pecos-quantum/src/lib.rs b/crates/pecos-quantum/src/lib.rs index 3f7f5ebc3..d6701cc9c 100644 --- a/crates/pecos-quantum/src/lib.rs +++ b/crates/pecos-quantum/src/lib.rs @@ -105,7 +105,8 @@ pub use channel::{ ChannelError, ChoiMatrix, DiagonalPtm, KrausOps, PauliChannel, PauliSum, Ptm, PtmBasisOrder, basis_bitmask, basis_digit_to_pauli, basis_element, basis_index, basis_label, bitmask_label, matrix_unit_basis, partial_trace, pauli_basis_len, pauli_string_to_bitmask, - pauli_to_basis_digit, random_1q_clifford, random_2q_clifford, random_clifford, random_pauli, + pauli_to_basis_digit, random_1q_clifford, random_2q_clifford, random_clifford, + random_density_matrix, random_density_matrix_with_rank, random_pauli, random_quantum_channel, }; pub use diamond_norm::{ DiamondNormError, hermitian_to_real_symmetric, hermitian_to_real_symmetric_with_tolerance, From 8c0b324b676a64b5949a13272c34158eaeb310f2 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 23:49:20 -0600 Subject: [PATCH 076/125] Add in-place Pauli bitmask conjugation --- crates/pecos-core/src/pauli/pauli_bitmask.rs | 314 ++++++++++++++----- 1 file changed, 230 insertions(+), 84 deletions(-) diff --git a/crates/pecos-core/src/pauli/pauli_bitmask.rs b/crates/pecos-core/src/pauli/pauli_bitmask.rs index b274b83e0..a7beef474 100644 --- a/crates/pecos-core/src/pauli/pauli_bitmask.rs +++ b/crates/pecos-core/src/pauli/pauli_bitmask.rs @@ -644,55 +644,79 @@ impl Copy for Conjugated {} /// Hadamard on qubit q: X↔Z, Y→-Y. #[must_use] pub fn conjugate_h(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { - let has_x = p.x_bits.get_bit(q); - let has_z = p.z_bits.get_bit(q); let mut label = p.clone(); - if has_x != has_z { - label.x_bits.xor_bit(q); - label.z_bits.xor_bit(q); - } + let sign_negative = conjugate_h_in_place(&mut label, q); Conjugated { label, - sign_negative: has_x && has_z, + sign_negative, + } +} + +/// In-place Hadamard conjugation on qubit q. +/// +/// Returns `true` when the conjugation contributes a negative sign. +#[must_use] +pub fn conjugate_h_in_place(p: &mut PauliBitmaskGeneric, q: usize) -> bool { + let has_x = p.x_bits.get_bit(q); + let has_z = p.z_bits.get_bit(q); + if has_x != has_z { + p.x_bits.xor_bit(q); + p.z_bits.xor_bit(q); } + has_x && has_z } /// SZ gate on qubit q: X→Y, Y→-X, Z→Z. #[must_use] pub fn conjugate_sz(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { - if !p.x_bits.get_bit(q) { - return Conjugated { - label: p.clone(), - sign_negative: false, - }; - } - let was_y = p.z_bits.get_bit(q); let mut label = p.clone(); - label.z_bits.xor_bit(q); + let sign_negative = conjugate_sz_in_place(&mut label, q); Conjugated { label, - sign_negative: was_y, + sign_negative, } } -/// `SZdg` gate on qubit q: X→-Y, Y→X, Z→Z. +/// In-place SZ conjugation on qubit q. +/// +/// Returns `true` when the conjugation contributes a negative sign. #[must_use] -pub fn conjugate_szdg(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { +pub fn conjugate_sz_in_place(p: &mut PauliBitmaskGeneric, q: usize) -> bool { if !p.x_bits.get_bit(q) { - return Conjugated { - label: p.clone(), - sign_negative: false, - }; + return false; } let was_y = p.z_bits.get_bit(q); + p.z_bits.xor_bit(q); + was_y +} + +/// `SZdg` gate on qubit q: X→-Y, Y→X, Z→Z. +#[must_use] +pub fn conjugate_szdg(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { let mut label = p.clone(); - label.z_bits.xor_bit(q); + let sign_negative = conjugate_szdg_in_place(&mut label, q); Conjugated { label, - sign_negative: !was_y, + sign_negative, } } +/// In-place `SZdg` conjugation on qubit q. +/// +/// Returns `true` when the conjugation contributes a negative sign. +#[must_use] +pub fn conjugate_szdg_in_place( + p: &mut PauliBitmaskGeneric, + q: usize, +) -> bool { + if !p.x_bits.get_bit(q) { + return false; + } + let was_y = p.z_bits.get_bit(q); + p.z_bits.xor_bit(q); + !was_y +} + /// CX (CNOT) with control c, target t: XI→XX, IZ→ZZ. /// /// The sign comes from Pauli multiplication phases when the control's @@ -707,6 +731,23 @@ pub fn conjugate_cx( c: usize, t: usize, ) -> Conjugated { + let mut label = p.clone(); + let sign_negative = conjugate_cx_in_place(&mut label, c, t); + Conjugated { + label, + sign_negative, + } +} + +/// In-place CX conjugation with control c and target t. +/// +/// Returns `true` when the conjugation contributes a negative sign. +#[must_use] +pub fn conjugate_cx_in_place( + p: &mut PauliBitmaskGeneric, + c: usize, + t: usize, +) -> bool { const PHASE: [[u8; 4]; 4] = [ [0, 0, 0, 0], // I·{I,X,Z,Y} [0, 0, 3, 1], // X·{I,X,Z,Y} @@ -718,12 +759,11 @@ pub fn conjugate_cx( let cz = p.z_bits.get_bit(c); let tx = p.x_bits.get_bit(t); let tz = p.z_bits.get_bit(t); - let mut label = p.clone(); if cx { - label.x_bits.xor_bit(t); + p.x_bits.xor_bit(t); } if tz { - label.z_bits.xor_bit(c); + p.z_bits.xor_bit(c); } // Pauli type encoding: I=0, X=1, Z=2, Y=3 (x + 2*z) // Phase from Pauli multiplication table: @@ -732,10 +772,7 @@ pub fn conjugate_cx( let pt = u8::from(tx) + 2 * u8::from(tz); let phase_c = if tz { PHASE[pc as usize][2] } else { 0 }; let phase_t = if cx { PHASE[1][pt as usize] } else { 0 }; - Conjugated { - label, - sign_negative: (phase_c + phase_t) % 4 == 2, - } + (phase_c + phase_t) % 4 == 2 } /// CZ on qubits a, b: XI→XZ, IX→ZX, ZI→ZI, IZ→IZ. @@ -745,50 +782,93 @@ pub fn conjugate_cz( a: usize, b: usize, ) -> Conjugated { + let mut label = p.clone(); + let sign_negative = conjugate_cz_in_place(&mut label, a, b); + Conjugated { + label, + sign_negative, + } +} + +/// In-place CZ conjugation on qubits a and b. +/// +/// Returns `true` when the conjugation contributes a negative sign. +#[must_use] +pub fn conjugate_cz_in_place( + p: &mut PauliBitmaskGeneric, + a: usize, + b: usize, +) -> bool { let ax = p.x_bits.get_bit(a); let az = p.z_bits.get_bit(a); let bx = p.x_bits.get_bit(b); let bz = p.z_bits.get_bit(b); - let mut label = p.clone(); if bx { - label.z_bits.xor_bit(a); + p.z_bits.xor_bit(a); } if ax { - label.z_bits.xor_bit(b); - } - Conjugated { - label, - sign_negative: ax && bx && (az != bz), + p.z_bits.xor_bit(b); } + ax && bx && (az != bz) } /// Pauli X gate on qubit q: Z→-Z, Y→-Y. #[must_use] pub fn conjugate_x(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + let mut label = p.clone(); + let sign_negative = conjugate_x_in_place(&mut label, q); Conjugated { - label: p.clone(), - sign_negative: p.z_bits.get_bit(q), + label, + sign_negative, } } +/// In-place Pauli X conjugation on qubit q. +/// +/// Returns `true` when the conjugation contributes a negative sign. +#[must_use] +pub fn conjugate_x_in_place(p: &mut PauliBitmaskGeneric, q: usize) -> bool { + p.z_bits.get_bit(q) +} + /// Pauli Y gate on qubit q: X→-X, Z→-Z. #[must_use] pub fn conjugate_y(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + let mut label = p.clone(); + let sign_negative = conjugate_y_in_place(&mut label, q); Conjugated { - label: p.clone(), - sign_negative: p.x_bits.get_bit(q) != p.z_bits.get_bit(q), + label, + sign_negative, } } +/// In-place Pauli Y conjugation on qubit q. +/// +/// Returns `true` when the conjugation contributes a negative sign. +#[must_use] +pub fn conjugate_y_in_place(p: &mut PauliBitmaskGeneric, q: usize) -> bool { + p.x_bits.get_bit(q) != p.z_bits.get_bit(q) +} + /// Pauli Z gate on qubit q: X→-X, Y→-Y. #[must_use] pub fn conjugate_z(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + let mut label = p.clone(); + let sign_negative = conjugate_z_in_place(&mut label, q); Conjugated { - label: p.clone(), - sign_negative: p.x_bits.get_bit(q), + label, + sign_negative, } } +/// In-place Pauli Z conjugation on qubit q. +/// +/// Returns `true` when the conjugation contributes a negative sign. +#[must_use] +pub fn conjugate_z_in_place(p: &mut PauliBitmaskGeneric, q: usize) -> bool { + p.x_bits.get_bit(q) +} + /// SWAP on qubits a, b: exchanges the Pauli at both sites. #[must_use] pub fn conjugate_swap( @@ -796,99 +876,154 @@ pub fn conjugate_swap( a: usize, b: usize, ) -> Conjugated { + let mut label = p.clone(); + let sign_negative = conjugate_swap_in_place(&mut label, a, b); + Conjugated { + label, + sign_negative, + } +} + +/// In-place SWAP conjugation on qubits a and b. +/// +/// Returns `true` when the conjugation contributes a negative sign. +#[must_use] +pub fn conjugate_swap_in_place( + p: &mut PauliBitmaskGeneric, + a: usize, + b: usize, +) -> bool { let ax = p.x_bits.get_bit(a); let az = p.z_bits.get_bit(a); let bx = p.x_bits.get_bit(b); let bz = p.z_bits.get_bit(b); - let mut label = p.clone(); // Clear both positions - label.x_bits.clear_bit(a); - label.x_bits.clear_bit(b); + p.x_bits.clear_bit(a); + p.x_bits.clear_bit(b); if az { - label.z_bits.clear_bit(a); + p.z_bits.clear_bit(a); } if bz { - label.z_bits.clear_bit(b); + p.z_bits.clear_bit(b); } // Set swapped if bx { - label.x_bits.set_bit(a); + p.x_bits.set_bit(a); } if ax { - label.x_bits.set_bit(b); + p.x_bits.set_bit(b); } if bz { - label.z_bits.set_bit(a); + p.z_bits.set_bit(a); } if az { - label.z_bits.set_bit(b); + p.z_bits.set_bit(b); } + false +} + +/// SX gate on qubit q: X→X, Z→-Y, Y→Z. +#[must_use] +pub fn conjugate_sx(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + let mut label = p.clone(); + let sign_negative = conjugate_sx_in_place(&mut label, q); Conjugated { label, - sign_negative: false, + sign_negative, } } -/// SX gate on qubit q: X→X, Z→-Y, Y→Z. +/// In-place SX conjugation on qubit q. +/// +/// Returns `true` when the conjugation contributes a negative sign. #[must_use] -pub fn conjugate_sx(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { +pub fn conjugate_sx_in_place(p: &mut PauliBitmaskGeneric, q: usize) -> bool { let xq = p.x_bits.get_bit(q); let zq = p.z_bits.get_bit(q); - let mut label = p.clone(); if zq { - label.x_bits.xor_bit(q); + p.x_bits.xor_bit(q); } + !xq && zq +} + +/// `SXdg` gate on qubit q: X→X, Z→Y, Y→-Z. +#[must_use] +pub fn conjugate_sxdg(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + let mut label = p.clone(); + let sign_negative = conjugate_sxdg_in_place(&mut label, q); Conjugated { label, - sign_negative: !xq && zq, + sign_negative, } } -/// `SXdg` gate on qubit q: X→X, Z→Y, Y→-Z. +/// In-place `SXdg` conjugation on qubit q. +/// +/// Returns `true` when the conjugation contributes a negative sign. #[must_use] -pub fn conjugate_sxdg(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { +pub fn conjugate_sxdg_in_place( + p: &mut PauliBitmaskGeneric, + q: usize, +) -> bool { let xq = p.x_bits.get_bit(q); let zq = p.z_bits.get_bit(q); - let mut label = p.clone(); if zq { - label.x_bits.xor_bit(q); + p.x_bits.xor_bit(q); } + xq && zq +} + +/// SY gate on qubit q: X→-Z, Y→Y, Z→X. +#[must_use] +pub fn conjugate_sy(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + let mut label = p.clone(); + let sign_negative = conjugate_sy_in_place(&mut label, q); Conjugated { label, - sign_negative: xq && zq, + sign_negative, } } -/// SY gate on qubit q: X→-Z, Y→Y, Z→X. +/// In-place SY conjugation on qubit q. +/// +/// Returns `true` when the conjugation contributes a negative sign. #[must_use] -pub fn conjugate_sy(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { +pub fn conjugate_sy_in_place(p: &mut PauliBitmaskGeneric, q: usize) -> bool { let xq = p.x_bits.get_bit(q); let zq = p.z_bits.get_bit(q); - let mut label = p.clone(); if xq != zq { - label.x_bits.xor_bit(q); - label.z_bits.xor_bit(q); + p.x_bits.xor_bit(q); + p.z_bits.xor_bit(q); } + xq && !zq +} + +/// `SYdg` gate on qubit q: X→Z, Y→Y, Z→-X. +#[must_use] +pub fn conjugate_sydg(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { + let mut label = p.clone(); + let sign_negative = conjugate_sydg_in_place(&mut label, q); Conjugated { label, - sign_negative: xq && !zq, + sign_negative, } } -/// `SYdg` gate on qubit q: X→Z, Y→Y, Z→-X. +/// In-place `SYdg` conjugation on qubit q. +/// +/// Returns `true` when the conjugation contributes a negative sign. #[must_use] -pub fn conjugate_sydg(p: &PauliBitmaskGeneric, q: usize) -> Conjugated { +pub fn conjugate_sydg_in_place( + p: &mut PauliBitmaskGeneric, + q: usize, +) -> bool { let xq = p.x_bits.get_bit(q); let zq = p.z_bits.get_bit(q); - let mut label = p.clone(); if xq != zq { - label.x_bits.xor_bit(q); - label.z_bits.xor_bit(q); - } - Conjugated { - label, - sign_negative: !xq && zq, + p.x_bits.xor_bit(q); + p.z_bits.xor_bit(q); } + !xq && zq } /// CY (controlled-Y) with control c, target t. @@ -903,15 +1038,26 @@ pub fn conjugate_cy( c: usize, t: usize, ) -> Conjugated { - let r1 = conjugate_szdg(p, t); - let r2 = conjugate_cx(&r1.label, c, t); - let r3 = conjugate_sz(&r2.label, t); + let mut label = p.clone(); + let sign_negative = conjugate_cy_in_place(&mut label, c, t); Conjugated { - label: r3.label, - sign_negative: r1.sign_negative ^ r2.sign_negative ^ r3.sign_negative, + label, + sign_negative, } } +/// In-place CY conjugation with control c and target t. +/// +/// Returns `true` when the conjugation contributes a negative sign. +#[must_use] +pub fn conjugate_cy_in_place( + p: &mut PauliBitmaskGeneric, + c: usize, + t: usize, +) -> bool { + conjugate_szdg_in_place(p, t) ^ conjugate_cx_in_place(p, c, t) ^ conjugate_sz_in_place(p, t) +} + #[cfg(test)] mod tests { use super::*; From 316ca92148215d02ef9829269e52b6f8d33ba141 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 23:51:39 -0600 Subject: [PATCH 077/125] Batch raw fault overlay masks --- .../src/fault_tolerance/fault_sampler.rs | 66 ++++++++++++++----- 1 file changed, 50 insertions(+), 16 deletions(-) diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index 80c321b81..8525b2f3c 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -1773,25 +1773,29 @@ impl RawMeasurementPlan { /// /// Complexity: O(p * shots) per mechanism (geometric = O(fired events)). fn overlay_faults_geometric(&self, shots: usize, columns: &mut [Vec], rng: &mut PecosRng) { + let num_words = columns.first().map_or(0, Vec::len); for (mech_idx, mechanism) in self.mechanisms.iter().enumerate() { let inv_log = self.inv_log_1_minus_p[mech_idx]; let p = mechanism.probability; let num_alts = mechanism.alternatives.len(); + if num_alts == 0 { + continue; + } // p=1: every shot fires (handle before inv_log check since inv_log=0 for p=1) if p >= 1.0 { - for shot in 0..shots { - let word_idx = shot / 64; - let bit_idx = shot % 64; - let mask = 1u64 << bit_idx; - let alt_idx = if num_alts == 1 { - 0 - } else { - rng.random_range(0..num_alts) - }; - for &meas_idx in &mechanism.alternatives[alt_idx] { - columns[meas_idx][word_idx] ^= mask; + if num_alts == 1 { + let word_masks = full_shot_word_masks(shots, num_words); + apply_word_masks(columns, &mechanism.alternatives[0], &word_masks); + } else { + let mut alt_word_masks = vec![vec![0u64; num_words]; num_alts]; + for shot in 0..shots { + let word_idx = shot / 64; + let bit_idx = shot % 64; + let alt_idx = rng.random_range(0..num_alts); + alt_word_masks[alt_idx][word_idx] ^= 1u64 << bit_idx; } + apply_alternative_word_masks(columns, mechanism, &alt_word_masks); } continue; } @@ -1803,6 +1807,7 @@ impl RawMeasurementPlan { // Geometric skip sampling: O(fired events) let mut shot: usize = 0; + let mut alt_word_masks: Option>> = None; while shot < shots { // Sample skip distance #[allow(clippy::cast_precision_loss)] @@ -1826,14 +1831,43 @@ impl RawMeasurementPlan { } else { rng.random_range(0..num_alts) }; - for &meas_idx in &mechanism.alternatives[alt_idx] { - if meas_idx < columns.len() { - columns[meas_idx][word_idx] ^= mask; - } - } + alt_word_masks.get_or_insert_with(|| vec![vec![0u64; num_words]; num_alts]) + [alt_idx][word_idx] ^= mask; shot += 1; } + if let Some(alt_word_masks) = alt_word_masks { + apply_alternative_word_masks(columns, mechanism, &alt_word_masks); + } + } + } +} + +fn full_shot_word_masks(shots: usize, num_words: usize) -> Vec { + let mut masks = vec![!0u64; num_words]; + mask_partial_final_word(std::slice::from_mut(&mut masks), shots); + masks +} + +fn apply_alternative_word_masks( + columns: &mut [Vec], + mechanism: &FaultMechanism, + alt_word_masks: &[Vec], +) { + for (measurements, word_masks) in mechanism.alternatives.iter().zip(alt_word_masks) { + apply_word_masks(columns, measurements, word_masks); + } +} + +fn apply_word_masks(columns: &mut [Vec], measurements: &[usize], word_masks: &[u64]) { + if word_masks.iter().all(|&mask| mask == 0) { + return; + } + for &meas_idx in measurements { + if let Some(column) = columns.get_mut(meas_idx) { + for (word, &mask) in column.iter_mut().zip(word_masks) { + *word ^= mask; + } } } } From 757d9789b14fa98468419a8974fec50415ec3727 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sat, 9 May 2026 23:56:34 -0600 Subject: [PATCH 078/125] Add dense stabilizer Pauli expectation access --- crates/pecos-simulators/src/dense_stab.rs | 96 ++++++++++++++++++++- crates/pecos-simulators/src/state_access.rs | 62 ++++++++++++- 2 files changed, 156 insertions(+), 2 deletions(-) diff --git a/crates/pecos-simulators/src/dense_stab.rs b/crates/pecos-simulators/src/dense_stab.rs index fc77da9fd..f0f95559a 100644 --- a/crates/pecos-simulators/src/dense_stab.rs +++ b/crates/pecos-simulators/src/dense_stab.rs @@ -51,7 +51,7 @@ use crate::{CliffordGateable, MeasurementResult, QuantumSimulator, StabilizerTableauSimulator}; use core::fmt::Debug; -use pecos_core::{QubitId, RngManageable}; +use pecos_core::{Pauli, PauliString, Phase, QuarterPhase, QubitId, RngManageable}; use pecos_random::rng_ext::RngProbabilityExt; use pecos_random::{PecosRng, Rng, SeedableRng}; @@ -1348,6 +1348,100 @@ impl StabilizerTableauSimulator for DenseS } impl DenseStab { + fn generator_from_rows( + num_qubits: usize, + words_per_row: usize, + row_x: &[u64], + row_z: &[u64], + signs_minus: &[u64], + signs_i: &[u64], + row: usize, + ) -> PauliString { + let mut phase = match (get_sign(signs_minus, row), get_sign(signs_i, row)) { + (false, false) => QuarterPhase::PlusOne, + (true, false) => QuarterPhase::MinusOne, + (false, true) => QuarterPhase::PlusI, + (true, true) => QuarterPhase::MinusI, + }; + let base = row * words_per_row; + let mut paulis = Vec::new(); + let mut num_y_terms = 0usize; + for qubit in 0..num_qubits { + let word_idx = base + qubit / 64; + let bit_mask = 1u64 << (qubit % 64); + let in_x = row_x[word_idx] & bit_mask != 0; + let in_z = row_z[word_idx] & bit_mask != 0; + let pauli = match (in_x, in_z) { + (false, false) => continue, + (true, false) => Pauli::X, + (false, true) => Pauli::Z, + (true, true) => { + num_y_terms += 1; + Pauli::Y + } + }; + paulis.push((pauli, QubitId::new(qubit))); + } + for _ in 0..num_y_terms { + phase = phase.multiply(&QuarterPhase::MinusI); + } + PauliString::with_phase_and_paulis(phase, paulis) + } + + fn generators_from_rows( + &self, + row_x: &[u64], + row_z: &[u64], + signs_minus: &[u64], + signs_i: &[u64], + ) -> Vec { + (0..self.num_qubits) + .map(|row| { + Self::generator_from_rows( + self.num_qubits, + self.words_per_row, + row_x, + row_z, + signs_minus, + signs_i, + row, + ) + }) + .collect() + } + + /// Extracts the stabilizer generators as a [`PauliStabilizerGroup`]. + /// + /// The dense tableau stores X/Z support plus two sign bits per row. This + /// converts that signed row representation into the shared algebraic + /// stabilizer type used by state inspection and quantum-info routines. + /// + /// [`PauliStabilizerGroup`]: pecos_quantum::PauliStabilizerGroup + #[must_use] + pub fn to_stabilizer_group(&self) -> pecos_quantum::PauliStabilizerGroup { + let generators = self.generators_from_rows( + &self.stab_row_x, + &self.stab_row_z, + &self.stab_signs_minus, + &self.stab_signs_i, + ); + pecos_quantum::PauliStabilizerGroup::from_generators_unchecked(generators) + } + + /// Extracts the destabilizer generators as a [`PauliSequence`]. + /// + /// [`PauliSequence`]: pecos_quantum::PauliSequence + #[must_use] + pub fn to_destabilizer_sequence(&self) -> pecos_quantum::PauliSequence { + let generators = self.generators_from_rows( + &self.destab_row_x, + &self.destab_row_z, + &self.destab_signs_minus, + &self.destab_signs_i, + ); + pecos_quantum::PauliSequence::new(generators) + } + /// Produces a tableau string from dense bit arrays. fn gen_tableau_string( num_qubits: usize, diff --git a/crates/pecos-simulators/src/state_access.rs b/crates/pecos-simulators/src/state_access.rs index cde56a329..6552041d3 100644 --- a/crates/pecos-simulators/src/state_access.rs +++ b/crates/pecos-simulators/src/state_access.rs @@ -18,6 +18,7 @@ //! propagation backends should not pretend to expose either. use crate::clifford_gateable::{CliffordGateable, MeasurementResult}; +use crate::dense_stab::DenseStab; use crate::density_matrix::DensityMatrix; use crate::quantum_simulator::QuantumSimulator; use crate::sparse_stab::{SparseStabGeneric, SparseStabHybrid}; @@ -632,6 +633,19 @@ where } } +impl PauliExpectationAccess for DenseStab +where + R: Rng + SeedableRng + Debug + Clone, +{ + fn pauli_expectation(&mut self, pauli: &PauliString) -> Result { + pauli_expectation_from_stabilizer_group( + &self.to_stabilizer_group(), + StateInfo::num_qubits(self), + pauli, + ) + } +} + impl PauliExpectationAccess for Stabilizer { fn pauli_expectation(&mut self, pauli: &PauliString) -> Result { pauli_expectation_from_stabilizer_group( @@ -941,7 +955,9 @@ fn pauli_expectation_from_stabilizer_group( #[cfg(test)] mod tests { use super::*; - use crate::{CliffordGateable, SparseStab, SparseStabHybrid, Stabilizer, StateVec, qid}; + use crate::{ + CliffordGateable, DenseStab, SparseStab, SparseStabHybrid, Stabilizer, StateVec, qid, + }; use pecos_core::QubitId; use pecos_core::pauli::algebra::i; use pecos_core::pauli::*; @@ -1119,6 +1135,20 @@ mod tests { } } + #[test] + fn dense_stab_pauli_expectation_matches_state_vector_for_bell_state() { + let mut state_vec = StateVec::new(2); + let mut dense = DenseStab::new(2); + state_vec.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); + dense.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); + + for pauli in [X(0) & X(1), Y(0) & Y(1), Z(0) & Z(1), X(0), Z(0)] { + let expected = state_vec.pauli_expectation(&pauli).unwrap(); + let actual = dense.pauli_expectation(&pauli).unwrap(); + assert_close(actual, expected); + } + } + #[test] fn sparse_stab_hybrid_supports_pauli_expectation_access() { let mut plus = SparseStabHybrid::new(1); @@ -1158,6 +1188,36 @@ mod tests { hybrid.pauli_expectation(&Y(0)).unwrap(), Complex64::new(1.0, 0.0), ); + + let mut dense = DenseStab::new(1); + dense.h(&qid(0)).sz(&qid(0)); + assert_close( + dense.pauli_expectation(&Y(0)).unwrap(), + Complex64::new(1.0, 0.0), + ); + assert_close( + dense.pauli_expectation(&X(0)).unwrap(), + Complex64::new(0.0, 0.0), + ); + } + + #[test] + fn dense_stab_pauli_expectation_preserves_signed_basis_state() { + let mut one = DenseStab::new(1); + one.x(&qid(0)); + + assert_close( + one.pauli_expectation(&Z(0)).unwrap(), + Complex64::new(-1.0, 0.0), + ); + assert_close( + one.pauli_expectation(&(-Z(0))).unwrap(), + Complex64::new(1.0, 0.0), + ); + assert_close( + one.pauli_expectation(&(i * Z(0))).unwrap(), + Complex64::new(0.0, -1.0), + ); } #[test] From 112e2f7e3d32ff53a541d5e91ca6348318d877dd Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 00:12:19 -0600 Subject: [PATCH 079/125] Expose quantum info primitives to Python --- Cargo.lock | 1 + python/pecos-rslib/Cargo.toml | 1 + python/pecos-rslib/pecos_rslib.pyi | 82 ++++ python/pecos-rslib/src/lib.rs | 4 + .../pecos-rslib/src/quantum_info_bindings.rs | 452 ++++++++++++++++++ .../quantum-pecos/src/pecos/quantum_info.py | 38 ++ .../tests/pecos/test_quantum_info_bindings.py | 87 ++++ 7 files changed, 665 insertions(+) create mode 100644 python/pecos-rslib/src/quantum_info_bindings.rs create mode 100644 python/quantum-pecos/src/pecos/quantum_info.py create mode 100644 python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py diff --git a/Cargo.lock b/Cargo.lock index 24b8bce23..9540dda0e 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -4358,6 +4358,7 @@ dependencies = [ "dirs", "libc", "log", + "nalgebra", "ndarray 0.17.2", "num-complex 0.4.6", "parking_lot", diff --git a/python/pecos-rslib/Cargo.toml b/python/pecos-rslib/Cargo.toml index 5d2ff85f6..965296fe0 100644 --- a/python/pecos-rslib/Cargo.toml +++ b/python/pecos-rslib/Cargo.toml @@ -65,6 +65,7 @@ pyo3 = { workspace = true, features = ["extension-module", "abi3-py310", "genera rayon.workspace = true rand.workspace = true ndarray.workspace = true +nalgebra.workspace = true num-complex.workspace = true parking_lot.workspace = true serde_json.workspace = true diff --git a/python/pecos-rslib/pecos_rslib.pyi b/python/pecos-rslib/pecos_rslib.pyi index f949198c5..3ee5a492a 100644 --- a/python/pecos-rslib/pecos_rslib.pyi +++ b/python/pecos-rslib/pecos_rslib.pyi @@ -21,6 +21,7 @@ from typing import ( Callable, Generic, Iterator, + Mapping, Sequence, TypeVar, overload, @@ -1152,6 +1153,71 @@ class PauliPropRs: ... +ComplexMatrix = Sequence[Sequence[complex]] +RealMatrix = Sequence[Sequence[float]] + +class PauliChannel: + """Sparse Pauli error channel represented by probabilities.""" + + @staticmethod + def one_qubit(px: float, py: float, pz: float) -> PauliChannel: ... + @staticmethod + def from_probabilities( + num_qubits: int, + probabilities: Mapping[str, float] | Sequence[tuple[str, float]], + ) -> PauliChannel: ... + def num_qubits(self) -> int: ... + def probabilities(self) -> dict[str, float]: ... + def total_error_rate(self) -> float: ... + def to_ptm(self) -> Ptm: ... + +class Ptm: + """Dense Pauli transfer matrix.""" + + def __init__(self, num_qubits: int, matrix: RealMatrix) -> None: ... + @staticmethod + def identity(num_qubits: int) -> Ptm: ... + def num_qubits(self) -> int: ... + def matrix(self) -> list[list[float]]: ... + def entry(self, output: int, input: int) -> float: ... + def to_choi(self) -> ChoiMatrix: ... + def to_kraus(self) -> KrausOps: ... + +class KrausOps: + """Kraus-operator channel representation.""" + + def __init__(self, num_qubits: int, operators: Sequence[ComplexMatrix]) -> None: ... + def num_qubits(self) -> int: ... + def operators(self) -> list[list[list[complex]]]: ... + def is_trace_preserving(self) -> bool: ... + def to_ptm(self) -> Ptm: ... + def to_choi(self) -> ChoiMatrix: ... + +class ChoiMatrix: + """Choi-matrix channel representation.""" + + def __init__(self, num_qubits: int, matrix: ComplexMatrix) -> None: ... + def num_qubits(self) -> int: ... + def matrix(self) -> list[list[complex]]: ... + def apply_to_operator(self, operator: ComplexMatrix) -> list[list[complex]]: ... + def partial_trace_output(self) -> list[list[complex]]: ... + def partial_trace_input(self) -> list[list[complex]]: ... + def is_completely_positive(self) -> bool: ... + def is_trace_preserving(self) -> bool: ... + def is_cptp(self) -> bool: ... + def is_unital(self) -> bool: ... + def to_ptm(self) -> Ptm: ... + def to_kraus(self) -> KrausOps: ... + +def state_fidelity(left: Sequence[complex], right: Sequence[complex]) -> float: ... +def state_fidelity_with_density_matrix(rho: ComplexMatrix, psi: Sequence[complex]) -> float: ... +def purity(rho: ComplexMatrix) -> float: ... +def process_fidelity(left: Ptm, right: Ptm) -> float: ... +def average_gate_fidelity(left: Ptm, right: Ptm) -> float: ... +def gate_error(left: Ptm, right: Ptm) -> float: ... +def random_density_matrix(num_qubits: int, seed: int) -> list[list[complex]]: ... +def random_quantum_channel(num_qubits: int, num_kraus: int, seed: int) -> KrausOps: ... + # ============================================================================= # Clifford Gate Constructors # ============================================================================= @@ -1247,6 +1313,22 @@ class quantum: DensityMatrixEngineBuilder: type[DensityMatrixEngineBuilder] CoinTossEngineBuilder: type[CoinTossEngineBuilder] +class quantum_info: + """Quantum-information channel and measure namespace.""" + + PauliChannel: type[PauliChannel] + Ptm: type[Ptm] + KrausOps: type[KrausOps] + ChoiMatrix: type[ChoiMatrix] + state_fidelity: Callable[[Sequence[complex], Sequence[complex]], float] + state_fidelity_with_density_matrix: Callable[[ComplexMatrix, Sequence[complex]], float] + purity: Callable[[ComplexMatrix], float] + process_fidelity: Callable[[Ptm, Ptm], float] + average_gate_fidelity: Callable[[Ptm, Ptm], float] + gate_error: Callable[[Ptm, Ptm], float] + random_density_matrix: Callable[[int, int], list[list[complex]]] + random_quantum_channel: Callable[[int, int, int], KrausOps] + class noise: """Noise model namespace.""" diff --git a/python/pecos-rslib/src/lib.rs b/python/pecos-rslib/src/lib.rs index 967cea03a..f22d4f96d 100644 --- a/python/pecos-rslib/src/lib.rs +++ b/python/pecos-rslib/src/lib.rs @@ -61,6 +61,7 @@ mod phir_json_bridge; mod programs_module; mod py_foreign_decoder; mod py_foreign_simulator; +mod quantum_info_bindings; mod shot_results_bindings; mod sim; mod simulator_utils; @@ -315,6 +316,9 @@ fn pecos_rslib(_py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> { // Register quantum circuit types (DagCircuit, Gate, GateType, QubitId) dag_circuit_bindings::register_quantum_circuit_types(m)?; + // Register quantum-information channel and measure types + quantum_info_bindings::register_quantum_info_module(m)?; + // Register gate registry types (GateRegistry, GateDefBuilder, AngleSource) gate_registry_bindings::register_gate_registry_types(m)?; diff --git a/python/pecos-rslib/src/quantum_info_bindings.rs b/python/pecos-rslib/src/quantum_info_bindings.rs new file mode 100644 index 000000000..e05dc5561 --- /dev/null +++ b/python/pecos-rslib/src/quantum_info_bindings.rs @@ -0,0 +1,452 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Thin Python bindings for PECOS quantum-information primitives. + +use std::collections::BTreeMap; + +use nalgebra::{DMatrix, DVector}; +use num_complex::Complex64; +use pecos_core::PauliBitmaskSmall; +use pecos_quantum::{ + ChoiMatrix as RustChoiMatrix, KrausOps as RustKrausOps, PauliChannel as RustPauliChannel, + Ptm as RustPtm, average_gate_fidelity as rust_average_gate_fidelity, + gate_error as rust_gate_error, pauli_basis_len, process_fidelity as rust_process_fidelity, + purity as rust_purity, random_density_matrix as rust_random_density_matrix, + random_quantum_channel as rust_random_quantum_channel, state_fidelity as rust_state_fidelity, + state_fidelity_with_density_matrix as rust_state_fidelity_with_density_matrix, +}; +use pecos_random::PecosRng; +use pyo3::prelude::*; +use pyo3::types::{PyDict, PyModule}; + +fn py_value_err(err: impl std::fmt::Display) -> PyErr { + pyo3::exceptions::PyValueError::new_err(err.to_string()) +} + +fn real_matrix_from_rows(rows: Vec>) -> PyResult> { + let row_count = rows.len(); + let col_count = rows.first().map_or(0, Vec::len); + if rows.iter().any(|row| row.len() != col_count) { + return Err(pyo3::exceptions::PyValueError::new_err( + "matrix rows must all have the same length", + )); + } + let data: Vec = rows.into_iter().flatten().collect(); + Ok(DMatrix::from_row_slice(row_count, col_count, &data)) +} + +fn complex_matrix_from_rows(rows: Vec>) -> PyResult> { + let row_count = rows.len(); + let col_count = rows.first().map_or(0, Vec::len); + if rows.iter().any(|row| row.len() != col_count) { + return Err(pyo3::exceptions::PyValueError::new_err( + "matrix rows must all have the same length", + )); + } + let data: Vec = rows.into_iter().flatten().collect(); + Ok(DMatrix::from_row_slice(row_count, col_count, &data)) +} + +fn real_matrix_to_rows(matrix: &DMatrix) -> Vec> { + (0..matrix.nrows()) + .map(|row| (0..matrix.ncols()).map(|col| matrix[(row, col)]).collect()) + .collect() +} + +fn complex_matrix_to_rows(matrix: &DMatrix) -> Vec> { + (0..matrix.nrows()) + .map(|row| (0..matrix.ncols()).map(|col| matrix[(row, col)]).collect()) + .collect() +} + +fn parse_pauli_label(num_qubits: usize, label: &str) -> PyResult { + let label = label.trim(); + if label.len() != num_qubits { + return Err(pyo3::exceptions::PyValueError::new_err(format!( + "Pauli label '{label}' has length {}, expected {num_qubits}", + label.len() + ))); + } + let mut index = 0usize; + for (qubit, ch) in label.chars().rev().enumerate() { + let digit = match ch { + 'I' => 0, + 'X' => 1, + 'Y' => 2, + 'Z' => 3, + _ => { + return Err(pyo3::exceptions::PyValueError::new_err(format!( + "invalid Pauli label '{label}'; expected only I, X, Y, Z" + ))); + } + }; + index |= digit << (2 * qubit); + } + pecos_quantum::basis_bitmask(num_qubits, index).map_err(py_value_err) +} + +fn pauli_probabilities_from_py( + num_qubits: usize, + probabilities: &Bound<'_, PyAny>, +) -> PyResult> { + let items: Vec<(String, f64)> = if let Ok(dict) = probabilities.cast::() { + dict.iter() + .map(|(key, value)| Ok((key.extract()?, value.extract()?))) + .collect::>()? + } else { + probabilities.extract()? + }; + items + .into_iter() + .map(|(label, probability)| Ok((parse_pauli_label(num_qubits, &label)?, probability))) + .collect() +} + +#[pyclass(name = "PauliChannel", module = "pecos_rslib.quantum_info")] +pub struct PyPauliChannel { + inner: RustPauliChannel, +} + +#[pymethods] +impl PyPauliChannel { + #[staticmethod] + fn one_qubit(px: f64, py: f64, pz: f64) -> PyResult { + Ok(Self { + inner: RustPauliChannel::one_qubit(px, py, pz).map_err(py_value_err)?, + }) + } + + #[staticmethod] + fn from_probabilities(num_qubits: usize, probabilities: &Bound<'_, PyAny>) -> PyResult { + Ok(Self { + inner: RustPauliChannel::try_new( + num_qubits, + pauli_probabilities_from_py(num_qubits, probabilities)?, + ) + .map_err(py_value_err)?, + }) + } + + fn num_qubits(&self) -> usize { + self.inner.num_qubits() + } + + fn probabilities(&self) -> PyResult> { + let mut out = BTreeMap::new(); + let basis_len = pauli_basis_len(self.inner.num_qubits()).map_err(py_value_err)?; + for basis_index in 0..basis_len { + let pauli = pecos_quantum::basis_bitmask(self.inner.num_qubits(), basis_index) + .map_err(py_value_err)?; + let probability = self.inner.probability(&pauli); + if probability > 0.0 { + out.insert( + pecos_quantum::basis_label(self.inner.num_qubits(), basis_index) + .map_err(py_value_err)?, + probability, + ); + } + } + Ok(out) + } + + fn total_error_rate(&self) -> f64 { + self.inner.total_error_rate() + } + + fn to_ptm(&self) -> PyResult { + Ok(PyPtm { + inner: self.inner.to_ptm().map_err(py_value_err)?, + }) + } + + fn __repr__(&self) -> String { + format!("PauliChannel(num_qubits={})", self.inner.num_qubits()) + } +} + +#[pyclass(name = "Ptm", module = "pecos_rslib.quantum_info")] +pub struct PyPtm { + inner: RustPtm, +} + +#[pymethods] +impl PyPtm { + #[new] + fn new(num_qubits: usize, matrix: Vec>) -> PyResult { + Ok(Self { + inner: RustPtm::try_new(num_qubits, real_matrix_from_rows(matrix)?) + .map_err(py_value_err)?, + }) + } + + #[staticmethod] + fn identity(num_qubits: usize) -> PyResult { + Ok(Self { + inner: RustPtm::identity(num_qubits).map_err(py_value_err)?, + }) + } + + fn num_qubits(&self) -> usize { + self.inner.num_qubits() + } + + fn matrix(&self) -> Vec> { + real_matrix_to_rows(self.inner.matrix()) + } + + fn entry(&self, output: usize, input: usize) -> f64 { + self.inner.entry(output, input) + } + + fn to_choi(&self) -> PyResult { + Ok(PyChoiMatrix { + inner: self.inner.to_choi().map_err(py_value_err)?, + }) + } + + fn to_kraus(&self) -> PyResult { + Ok(PyKrausOps { + inner: self.inner.to_kraus().map_err(py_value_err)?, + }) + } + + fn __repr__(&self) -> String { + format!("Ptm(num_qubits={})", self.inner.num_qubits()) + } +} + +#[pyclass(name = "KrausOps", module = "pecos_rslib.quantum_info")] +pub struct PyKrausOps { + inner: RustKrausOps, +} + +#[pymethods] +impl PyKrausOps { + #[new] + fn new(num_qubits: usize, operators: Vec>>) -> PyResult { + let operators = operators + .into_iter() + .map(complex_matrix_from_rows) + .collect::>>()?; + Ok(Self { + inner: RustKrausOps::try_new(num_qubits, operators).map_err(py_value_err)?, + }) + } + + fn num_qubits(&self) -> usize { + self.inner.num_qubits() + } + + fn operators(&self) -> Vec>> { + self.inner + .operators() + .iter() + .map(complex_matrix_to_rows) + .collect() + } + + fn is_trace_preserving(&self) -> bool { + self.inner.is_trace_preserving() + } + + fn to_ptm(&self) -> PyResult { + Ok(PyPtm { + inner: self.inner.to_ptm().map_err(py_value_err)?, + }) + } + + fn to_choi(&self) -> PyResult { + Ok(PyChoiMatrix { + inner: self.inner.to_choi().map_err(py_value_err)?, + }) + } + + fn __repr__(&self) -> String { + format!("KrausOps(num_qubits={})", self.inner.num_qubits()) + } +} + +#[pyclass(name = "ChoiMatrix", module = "pecos_rslib.quantum_info")] +pub struct PyChoiMatrix { + inner: RustChoiMatrix, +} + +#[pymethods] +impl PyChoiMatrix { + #[new] + fn new(num_qubits: usize, matrix: Vec>) -> PyResult { + Ok(Self { + inner: RustChoiMatrix::try_new(num_qubits, complex_matrix_from_rows(matrix)?) + .map_err(py_value_err)?, + }) + } + + fn num_qubits(&self) -> usize { + self.inner.num_qubits() + } + + fn matrix(&self) -> Vec> { + complex_matrix_to_rows(self.inner.matrix()) + } + + fn apply_to_operator(&self, operator: Vec>) -> PyResult>> { + Ok(complex_matrix_to_rows( + &self + .inner + .apply_to_operator(&complex_matrix_from_rows(operator)?) + .map_err(py_value_err)?, + )) + } + + fn partial_trace_output(&self) -> PyResult>> { + Ok(complex_matrix_to_rows( + &self.inner.partial_trace_output().map_err(py_value_err)?, + )) + } + + fn partial_trace_input(&self) -> PyResult>> { + Ok(complex_matrix_to_rows( + &self.inner.partial_trace_input().map_err(py_value_err)?, + )) + } + + fn is_completely_positive(&self) -> bool { + self.inner.is_completely_positive() + } + + fn is_trace_preserving(&self) -> bool { + self.inner.is_trace_preserving() + } + + fn is_cptp(&self) -> bool { + self.inner.is_cptp() + } + + fn is_unital(&self) -> bool { + self.inner.is_unital() + } + + fn to_ptm(&self) -> PyResult { + Ok(PyPtm { + inner: self.inner.to_ptm().map_err(py_value_err)?, + }) + } + + fn to_kraus(&self) -> PyResult { + Ok(PyKrausOps { + inner: self.inner.to_kraus().map_err(py_value_err)?, + }) + } + + fn __repr__(&self) -> String { + format!("ChoiMatrix(num_qubits={})", self.inner.num_qubits()) + } +} + +#[pyfunction] +fn state_fidelity(left: Vec, right: Vec) -> PyResult { + rust_state_fidelity(&DVector::from_vec(left), &DVector::from_vec(right)).map_err(py_value_err) +} + +#[pyfunction] +fn state_fidelity_with_density_matrix( + rho: Vec>, + psi: Vec, +) -> PyResult { + rust_state_fidelity_with_density_matrix( + &complex_matrix_from_rows(rho)?, + &DVector::from_vec(psi), + ) + .map_err(py_value_err) +} + +#[pyfunction] +fn purity(rho: Vec>) -> PyResult { + rust_purity(&complex_matrix_from_rows(rho)?).map_err(py_value_err) +} + +#[pyfunction] +fn process_fidelity(left: &PyPtm, right: &PyPtm) -> PyResult { + rust_process_fidelity(&left.inner, &right.inner).map_err(py_value_err) +} + +#[pyfunction] +fn average_gate_fidelity(left: &PyPtm, right: &PyPtm) -> PyResult { + rust_average_gate_fidelity(&left.inner, &right.inner).map_err(py_value_err) +} + +#[pyfunction] +fn gate_error(left: &PyPtm, right: &PyPtm) -> PyResult { + rust_gate_error(&left.inner, &right.inner).map_err(py_value_err) +} + +#[pyfunction] +fn random_density_matrix(num_qubits: usize, seed: u64) -> PyResult>> { + let mut rng = PecosRng::seed_from_u64(seed); + Ok(complex_matrix_to_rows( + &rust_random_density_matrix(&mut rng, num_qubits).map_err(py_value_err)?, + )) +} + +#[pyfunction] +fn random_quantum_channel(num_qubits: usize, num_kraus: usize, seed: u64) -> PyResult { + let mut rng = PecosRng::seed_from_u64(seed); + Ok(PyKrausOps { + inner: rust_random_quantum_channel(&mut rng, num_qubits, num_kraus) + .map_err(py_value_err)?, + }) +} + +pub fn register_quantum_info_module(parent: &Bound<'_, PyModule>) -> PyResult<()> { + parent.add_class::()?; + parent.add_class::()?; + parent.add_class::()?; + parent.add_class::()?; + + parent.add_function(wrap_pyfunction!(state_fidelity, parent)?)?; + parent.add_function(wrap_pyfunction!( + state_fidelity_with_density_matrix, + parent + )?)?; + parent.add_function(wrap_pyfunction!(purity, parent)?)?; + parent.add_function(wrap_pyfunction!(process_fidelity, parent)?)?; + parent.add_function(wrap_pyfunction!(average_gate_fidelity, parent)?)?; + parent.add_function(wrap_pyfunction!(gate_error, parent)?)?; + parent.add_function(wrap_pyfunction!(random_density_matrix, parent)?)?; + parent.add_function(wrap_pyfunction!(random_quantum_channel, parent)?)?; + + let py = parent.py(); + let module = PyModule::new(py, "quantum_info")?; + for name in [ + "PauliChannel", + "Ptm", + "KrausOps", + "ChoiMatrix", + "state_fidelity", + "state_fidelity_with_density_matrix", + "purity", + "process_fidelity", + "average_gate_fidelity", + "gate_error", + "random_density_matrix", + "random_quantum_channel", + ] { + module.add(name, parent.getattr(name)?)?; + } + + let sys = py.import("sys")?; + let modules = sys.getattr("modules")?; + modules.set_item("pecos_rslib.quantum_info", &module)?; + parent.add_submodule(&module)?; + Ok(()) +} diff --git a/python/quantum-pecos/src/pecos/quantum_info.py b/python/quantum-pecos/src/pecos/quantum_info.py new file mode 100644 index 000000000..5232b9aff --- /dev/null +++ b/python/quantum-pecos/src/pecos/quantum_info.py @@ -0,0 +1,38 @@ +"""Quantum-information channel representations and measures. + +This module re-exports the Rust-backed implementations from +``pecos_rslib.quantum_info``. Computation and validation happen in Rust; this +file only provides the public Python import location. +""" + +from __future__ import annotations + +from pecos_rslib.quantum_info import ( + ChoiMatrix, + KrausOps, + PauliChannel, + Ptm, + average_gate_fidelity, + gate_error, + process_fidelity, + purity, + random_density_matrix, + random_quantum_channel, + state_fidelity, + state_fidelity_with_density_matrix, +) + +__all__ = [ + "ChoiMatrix", + "KrausOps", + "PauliChannel", + "Ptm", + "average_gate_fidelity", + "gate_error", + "process_fidelity", + "purity", + "random_density_matrix", + "random_quantum_channel", + "state_fidelity", + "state_fidelity_with_density_matrix", +] diff --git a/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py b/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py new file mode 100644 index 000000000..dae4ce1bc --- /dev/null +++ b/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py @@ -0,0 +1,87 @@ +from __future__ import annotations + +from pecos.quantum_info import ( + ChoiMatrix, + PauliChannel, + Ptm, + average_gate_fidelity, + gate_error, + process_fidelity, + purity, + random_density_matrix, + random_quantum_channel, + state_fidelity, + state_fidelity_with_density_matrix, +) + + +def assert_close(actual: float, expected: float, tol: float = 1e-12) -> None: + assert abs(actual - expected) < tol + + +def assert_matrix_close(actual: list[list[complex]], expected: list[list[complex]]) -> None: + assert len(actual) == len(expected) + for actual_row, expected_row in zip(actual, expected, strict=True): + assert len(actual_row) == len(expected_row) + for actual_value, expected_value in zip(actual_row, expected_row, strict=True): + assert abs(actual_value - expected_value) < 1e-12 + + +def test_pauli_channel_exposes_probabilities_and_ptm() -> None: + channel = PauliChannel.one_qubit(0.1, 0.2, 0.0) + + assert channel.num_qubits() == 1 + assert_close(channel.total_error_rate(), 0.3) + assert channel.probabilities() == {"I": 0.7, "X": 0.1, "Y": 0.2} + + ptm = channel.to_ptm() + assert ptm.num_qubits() == 1 + assert_close(ptm.entry(0, 0), 1.0) + + +def test_choi_and_kraus_wrappers_round_trip_identity_channel() -> None: + identity = Ptm.identity(1) + choi = identity.to_choi() + + assert isinstance(choi, ChoiMatrix) + assert choi.is_completely_positive() + assert choi.is_trace_preserving() + assert choi.is_cptp() + assert choi.is_unital() + assert_matrix_close( + choi.partial_trace_output(), + [[1.0 + 0.0j, 0.0 + 0.0j], [0.0 + 0.0j, 1.0 + 0.0j]], + ) + + kraus = choi.to_kraus() + assert kraus.num_qubits() == 1 + assert kraus.is_trace_preserving() + assert_close(process_fidelity(kraus.to_ptm(), identity), 1.0) + assert_close(average_gate_fidelity(kraus.to_ptm(), identity), 1.0) + assert_close(gate_error(kraus.to_ptm(), identity), 0.0) + + +def test_state_measure_wrappers() -> None: + zero = [1.0 + 0.0j, 0.0 + 0.0j] + plus = [2.0**-0.5 + 0.0j, 2.0**-0.5 + 0.0j] + zero_density = [[1.0 + 0.0j, 0.0 + 0.0j], [0.0 + 0.0j, 0.0 + 0.0j]] + + assert_close(state_fidelity(zero, zero), 1.0) + assert_close(state_fidelity(zero, plus), 0.5) + assert_close(state_fidelity_with_density_matrix(zero_density, zero), 1.0) + assert_close(purity(zero_density), 1.0) + + +def test_random_generators_are_seed_reproducible_and_valid() -> None: + rho = random_density_matrix(1, 123) + same_rho = random_density_matrix(1, 123) + different_rho = random_density_matrix(1, 124) + + assert rho == same_rho + assert rho != different_rho + assert_close((rho[0][0] + rho[1][1]).real, 1.0) + + channel = random_quantum_channel(1, 2, 123) + same_channel = random_quantum_channel(1, 2, 123) + assert channel.operators() == same_channel.operators() + assert channel.is_trace_preserving() From 5788624261b649d7657f439fe3f3e649b77f5f4b Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 00:13:24 -0600 Subject: [PATCH 080/125] Document quantum info primitives --- docs/user-guide/quantum-info.md | 131 ++++++++++++++++++++++++++++++++ mkdocs.yml | 1 + 2 files changed, 132 insertions(+) create mode 100644 docs/user-guide/quantum-info.md diff --git a/docs/user-guide/quantum-info.md b/docs/user-guide/quantum-info.md new file mode 100644 index 000000000..aba7ec023 --- /dev/null +++ b/docs/user-guide/quantum-info.md @@ -0,0 +1,131 @@ +# Quantum Information Primitives + +PECOS exposes Rust-backed channel representations and measure functions for +workflows that connect process characterization to QEC simulation. These APIs +live at `pecos.quantum_info` in Python and in the `pecos-quantum` crate in Rust. + +Use these types when you need exact channel data, validation, or process +metrics before reducing a model to Pauli rates, a detector error model, or a +fault catalog. + +## Channel Representations + +PECOS currently provides four concrete channel representations: + +| Type | Purpose | +| ---- | ------- | +| `PauliChannel` | Sparse Pauli error probabilities. | +| `Ptm` | Dense Pauli transfer matrix. | +| `KrausOps` | Kraus-operator representation. | +| `ChoiMatrix` | Choi-matrix representation for channel validation and tomography. | + +The representations use PECOS's little-endian qubit convention. Pauli-channel +labels are displayed with the highest-numbered qubit first, so label `IX` on two +qubits means identity on qubit 1 and X on qubit 0. + +```python +from pecos.quantum_info import PauliChannel, process_fidelity + +channel = PauliChannel.one_qubit(px=0.001, py=0.0005, pz=0.002) +print(channel.probabilities()) +print(channel.total_error_rate()) + +ptm = channel.to_ptm() +identity = type(ptm).identity(1) +print(process_fidelity(ptm, identity)) +``` + +For multi-qubit Pauli channels, pass a label-to-probability map: + +```python +from pecos.quantum_info import PauliChannel + +channel = PauliChannel.from_probabilities( + 2, + { + "II": 0.98, + "IX": 0.01, + "ZI": 0.01, + }, +) +``` + +## Choi Validation + +`ChoiMatrix` exposes checks that are useful when importing reconstructed +processes from tomography or generated channels from another model: + +```python +from pecos.quantum_info import Ptm + +choi = Ptm.identity(1).to_choi() +assert choi.is_completely_positive() +assert choi.is_trace_preserving() +assert choi.is_cptp() +assert choi.is_unital() + +trace_check = choi.partial_trace_output() +``` + +For PECOS's Choi convention, a trace-preserving channel satisfies +`partial_trace_output() == I`. + +## State and Process Measures + +State measures accept Python lists of complex values: + +```python +from pecos.quantum_info import purity, state_fidelity + +zero = [1.0 + 0.0j, 0.0 + 0.0j] +plus = [2.0**-0.5, 2.0**-0.5] + +assert state_fidelity(zero, zero) == 1.0 +assert abs(state_fidelity(zero, plus) - 0.5) < 1e-12 + +rho_zero = [[1.0 + 0.0j, 0.0 + 0.0j], [0.0 + 0.0j, 0.0 + 0.0j]] +assert purity(rho_zero) == 1.0 +``` + +Process measures operate on `Ptm` values: + +```python +from pecos.quantum_info import Ptm, average_gate_fidelity, gate_error + +ideal = Ptm.identity(1) +actual = Ptm.identity(1) + +assert average_gate_fidelity(actual, ideal) == 1.0 +assert gate_error(actual, ideal) == 0.0 +``` + +## Random Generators + +Seeded random generators are available for tests and examples: + +```python +from pecos.quantum_info import random_density_matrix, random_quantum_channel + +rho = random_density_matrix(num_qubits=1, seed=123) +channel = random_quantum_channel(num_qubits=1, num_kraus=2, seed=123) +assert channel.is_trace_preserving() +``` + +`random_density_matrix` samples Hilbert-Schmidt random density matrices. +`random_quantum_channel` samples CPTP channels through a random Stinespring +isometry. + +## Relationship to QEC APIs + +These channel and measure APIs are exact quantum-information tools. They do not +replace detector error models, fault catalogs, or decoders. A typical workflow +is: + +1. Characterize or construct a channel as `KrausOps`, `ChoiMatrix`, `Ptm`, or + `PauliChannel`. +2. Validate the channel and compute state or process measures. +3. Reduce the channel to the noise model needed by a QEC simulation. +4. Build a DEM or fault catalog and estimate logical error rate with a decoder. + +This separation keeps exact channel analysis distinct from the compressed fault +models used for large-scale QEC studies. diff --git a/mkdocs.yml b/mkdocs.yml index 2d930b036..4aff8d6c1 100644 --- a/mkdocs.yml +++ b/mkdocs.yml @@ -62,6 +62,7 @@ nav: - Gate and Angle Types: user-guide/gate-angle-types.md - Noise Model Builders: user-guide/noise-model-builders.md - Quantum Operator Algebra: user-guide/quantum-operator-algebra.md + - Quantum Information Primitives: user-guide/quantum-info.md - Stabilizer Codes: user-guide/stabilizer-codes.md - Pauli Algebra and QEC in Python: user-guide/python-pauli-qec.md - Fault Tolerance Analysis: user-guide/fault-tolerance.md From efeba544de33041d1eb79f7236a19f6e8ada9424 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 00:24:31 -0600 Subject: [PATCH 081/125] Add Pauli channel diamond norm --- crates/pecos-quantum/src/diamond_norm.rs | 130 ++++++++++++++++-- crates/pecos-quantum/src/lib.rs | 4 +- docs/user-guide/quantum-info.md | 17 +++ python/pecos-rslib/pecos_rslib.pyi | 4 + .../pecos-rslib/src/quantum_info_bindings.rs | 14 ++ .../quantum-pecos/src/pecos/quantum_info.py | 4 + .../tests/pecos/test_quantum_info_bindings.py | 6 + 7 files changed, 166 insertions(+), 13 deletions(-) diff --git a/crates/pecos-quantum/src/diamond_norm.rs b/crates/pecos-quantum/src/diamond_norm.rs index 167389186..87d4c4593 100644 --- a/crates/pecos-quantum/src/diamond_norm.rs +++ b/crates/pecos-quantum/src/diamond_norm.rs @@ -10,13 +10,12 @@ // or implied. See the License for the specific language governing permissions and limitations under // the License. -//! Internal linear-algebra helpers for a future Rust diamond-norm solver. +//! Diamond-norm utilities. //! -//! This module deliberately does not expose a public `diamond_norm` routine or -//! add an SDP solver dependency yet. It contains the convention-sensitive pieces -//! needed before a feature-gated conic-solver integration is reviewable: -//! Clarabel-style scaled triangular vectorization for real PSD cones and the -//! standard complex-Hermitian to real-symmetric embedding. +//! General channel diamond norm requires solving a semidefinite program. PECOS +//! does not add an external SDP dependency for that. This module exposes exact +//! dependency-free cases that are mathematically closed-form today, plus the +//! linear-algebra pieces needed by a future PECOS-owned general solver. use std::error::Error; use std::fmt; @@ -24,6 +23,8 @@ use std::fmt; use nalgebra::DMatrix; use num_complex::Complex64; +use crate::channel::{PauliChannel, basis_bitmask, pauli_basis_len}; + const DEFAULT_TOLERANCE: f64 = 1e-12; /// Error returned by diamond-norm linear-algebra helpers. @@ -53,6 +54,18 @@ pub enum DiamondNormError { }, /// A matrix entry was not finite. NonFiniteEntry, + /// Two channel representations act on different Hilbert spaces. + QubitCountMismatch { + /// Left channel qubit count. + left: usize, + /// Right channel qubit count. + right: usize, + }, + /// Failed to enumerate the Pauli basis for a channel. + PauliBasis { + /// Underlying reason. + reason: String, + }, } impl fmt::Display for DiamondNormError { @@ -73,12 +86,70 @@ impl fmt::Display for DiamondNormError { "matrix is not Hermitian/symmetric within tolerance {tolerance}; max difference {max_difference}" ), Self::NonFiniteEntry => write!(f, "matrix contains a non-finite entry"), + Self::QubitCountMismatch { left, right } => write!( + f, + "channels must act on the same number of qubits, got {left} and {right}" + ), + Self::PauliBasis { reason } => { + write!(f, "failed to enumerate Pauli basis: {reason}") + } } } } impl Error for DiamondNormError {} +/// Returns `||left - right||_diamond` for two Pauli channels. +/// +/// For Pauli channels, the diamond norm of the channel difference is exactly +/// the L1 distance between the two Pauli probability vectors. Applying the +/// channel difference to half of a maximally entangled state produces +/// orthogonal Pauli-labelled Bell states, so no SDP is needed. +/// +/// # Errors +/// +/// Returns an error if the channels act on different numbers of qubits or the +/// Pauli basis size overflows. +pub fn pauli_channel_diamond_norm( + left: &PauliChannel, + right: &PauliChannel, +) -> Result { + if left.num_qubits() != right.num_qubits() { + return Err(DiamondNormError::QubitCountMismatch { + left: left.num_qubits(), + right: right.num_qubits(), + }); + } + let num_qubits = left.num_qubits(); + let basis_len = pauli_basis_len(num_qubits).map_err(|err| DiamondNormError::PauliBasis { + reason: err.to_string(), + })?; + let mut total = 0.0; + for basis_index in 0..basis_len { + let pauli = + basis_bitmask(num_qubits, basis_index).map_err(|err| DiamondNormError::PauliBasis { + reason: err.to_string(), + })?; + total += (left.probability(&pauli) - right.probability(&pauli)).abs(); + } + Ok(total) +} + +/// Returns the diamond distance between two Pauli channels. +/// +/// The diamond distance is `0.5 * ||left - right||_diamond`, matching the +/// standard trace-distance normalization. +/// +/// # Errors +/// +/// Returns an error if [`pauli_channel_diamond_norm`] fails. +pub fn pauli_channel_diamond_distance( + left: &PauliChannel, + right: &PauliChannel, +) -> Result { + Ok(0.5 * pauli_channel_diamond_norm(left, right)?) +} + /// Returns the length of the scaled upper-triangular vector for an `n x n` /// symmetric matrix. #[must_use] @@ -86,7 +157,7 @@ pub const fn scaled_psd_triangle_len(n: usize) -> usize { n * (n + 1) / 2 } -/// Converts a real symmetric matrix to Clarabel-style scaled upper-triangular +/// Converts a real symmetric matrix to scaled upper-triangular /// vector form. /// /// Diagonal entries are stored unchanged. Strict upper-triangular entries are @@ -125,7 +196,7 @@ pub fn svec_real_symmetric_with_tolerance( Ok(out) } -/// Converts Clarabel-style scaled upper-triangular vector form back to a real +/// Converts scaled upper-triangular vector form back to a real /// symmetric matrix. /// /// # Errors @@ -165,9 +236,8 @@ pub fn smat_real_symmetric(n: usize, data: &[f64]) -> Result, Diamo /// [ Y X ] /// ``` /// -/// This embedding maps complex PSD constraints into real PSD constraints and is -/// the representation needed before modeling the diamond-norm SDP in a real -/// conic solver. +/// This embedding maps complex PSD constraints into real PSD constraints, which +/// is the representation needed by a real-valued PECOS SDP implementation. /// /// # Errors /// @@ -259,11 +329,49 @@ fn validate_hermitian(matrix: &DMatrix, tolerance: f64) -> Result<(), #[cfg(test)] mod tests { use super::*; + use std::collections::BTreeMap; fn assert_close(left: f64, right: f64) { assert!((left - right).abs() < 1e-12, "{left} != {right}"); } + #[test] + fn pauli_channel_diamond_norm_is_l1_probability_distance() { + let left = PauliChannel::one_qubit(0.1, 0.2, 0.0).unwrap(); + let right = PauliChannel::one_qubit(0.0, 0.2, 0.3).unwrap(); + + assert_close(pauli_channel_diamond_norm(&left, &right).unwrap(), 0.6); + assert_close(pauli_channel_diamond_distance(&left, &right).unwrap(), 0.3); + } + + #[test] + fn pauli_channel_diamond_norm_includes_absent_terms_as_zero() { + let mut left_probs = BTreeMap::new(); + left_probs.insert(basis_bitmask(2, 0).unwrap(), 0.9); + left_probs.insert(basis_bitmask(2, 5).unwrap(), 0.1); + let left = PauliChannel::try_new(2, left_probs).unwrap(); + + let mut right_probs = BTreeMap::new(); + right_probs.insert(basis_bitmask(2, 0).unwrap(), 0.8); + right_probs.insert(basis_bitmask(2, 10).unwrap(), 0.2); + let right = PauliChannel::try_new(2, right_probs).unwrap(); + + assert_close(pauli_channel_diamond_norm(&left, &right).unwrap(), 0.4); + } + + #[test] + fn pauli_channel_diamond_norm_rejects_qubit_count_mismatch() { + let left = PauliChannel::one_qubit(0.1, 0.0, 0.0).unwrap(); + let mut right_probs = BTreeMap::new(); + right_probs.insert(basis_bitmask(2, 0).unwrap(), 1.0); + let right = PauliChannel::try_new(2, right_probs).unwrap(); + + assert!(matches!( + pauli_channel_diamond_norm(&left, &right).unwrap_err(), + DiamondNormError::QubitCountMismatch { left: 1, right: 2 } + )); + } + fn frobenius_inner(left: &DMatrix, right: &DMatrix) -> f64 { left.iter().zip(right.iter()).map(|(a, b)| a * b).sum() } diff --git a/crates/pecos-quantum/src/lib.rs b/crates/pecos-quantum/src/lib.rs index d6701cc9c..41dd803c5 100644 --- a/crates/pecos-quantum/src/lib.rs +++ b/crates/pecos-quantum/src/lib.rs @@ -110,8 +110,8 @@ pub use channel::{ }; pub use diamond_norm::{ DiamondNormError, hermitian_to_real_symmetric, hermitian_to_real_symmetric_with_tolerance, - scaled_psd_triangle_len, smat_real_symmetric, svec_real_symmetric, - svec_real_symmetric_with_tolerance, + pauli_channel_diamond_distance, pauli_channel_diamond_norm, scaled_psd_triangle_len, + smat_real_symmetric, svec_real_symmetric, svec_real_symmetric_with_tolerance, }; pub use measures::{ DensityMatrixPartialTrace, MeasureError, average_gate_fidelity, concurrence, diff --git a/docs/user-guide/quantum-info.md b/docs/user-guide/quantum-info.md index aba7ec023..ceef59e57 100644 --- a/docs/user-guide/quantum-info.md +++ b/docs/user-guide/quantum-info.md @@ -35,6 +35,23 @@ identity = type(ptm).identity(1) print(process_fidelity(ptm, identity)) ``` +For Pauli channels, PECOS also provides exact dependency-free diamond norm and +diamond distance helpers: + +```python +from pecos.quantum_info import ( + PauliChannel, + pauli_channel_diamond_distance, + pauli_channel_diamond_norm, +) + +left = PauliChannel.one_qubit(0.001, 0.0, 0.0) +right = PauliChannel.one_qubit(0.0, 0.0, 0.001) + +print(pauli_channel_diamond_norm(left, right)) +print(pauli_channel_diamond_distance(left, right)) +``` + For multi-qubit Pauli channels, pass a label-to-probability map: ```python diff --git a/python/pecos-rslib/pecos_rslib.pyi b/python/pecos-rslib/pecos_rslib.pyi index 3ee5a492a..a30a2722f 100644 --- a/python/pecos-rslib/pecos_rslib.pyi +++ b/python/pecos-rslib/pecos_rslib.pyi @@ -1215,6 +1215,8 @@ def purity(rho: ComplexMatrix) -> float: ... def process_fidelity(left: Ptm, right: Ptm) -> float: ... def average_gate_fidelity(left: Ptm, right: Ptm) -> float: ... def gate_error(left: Ptm, right: Ptm) -> float: ... +def pauli_channel_diamond_norm(left: PauliChannel, right: PauliChannel) -> float: ... +def pauli_channel_diamond_distance(left: PauliChannel, right: PauliChannel) -> float: ... def random_density_matrix(num_qubits: int, seed: int) -> list[list[complex]]: ... def random_quantum_channel(num_qubits: int, num_kraus: int, seed: int) -> KrausOps: ... @@ -1326,6 +1328,8 @@ class quantum_info: process_fidelity: Callable[[Ptm, Ptm], float] average_gate_fidelity: Callable[[Ptm, Ptm], float] gate_error: Callable[[Ptm, Ptm], float] + pauli_channel_diamond_norm: Callable[[PauliChannel, PauliChannel], float] + pauli_channel_diamond_distance: Callable[[PauliChannel, PauliChannel], float] random_density_matrix: Callable[[int, int], list[list[complex]]] random_quantum_channel: Callable[[int, int, int], KrausOps] diff --git a/python/pecos-rslib/src/quantum_info_bindings.rs b/python/pecos-rslib/src/quantum_info_bindings.rs index e05dc5561..3b912d4f6 100644 --- a/python/pecos-rslib/src/quantum_info_bindings.rs +++ b/python/pecos-rslib/src/quantum_info_bindings.rs @@ -390,6 +390,16 @@ fn gate_error(left: &PyPtm, right: &PyPtm) -> PyResult { rust_gate_error(&left.inner, &right.inner).map_err(py_value_err) } +#[pyfunction] +fn pauli_channel_diamond_norm(left: &PyPauliChannel, right: &PyPauliChannel) -> PyResult { + pecos_quantum::pauli_channel_diamond_norm(&left.inner, &right.inner).map_err(py_value_err) +} + +#[pyfunction] +fn pauli_channel_diamond_distance(left: &PyPauliChannel, right: &PyPauliChannel) -> PyResult { + pecos_quantum::pauli_channel_diamond_distance(&left.inner, &right.inner).map_err(py_value_err) +} + #[pyfunction] fn random_density_matrix(num_qubits: usize, seed: u64) -> PyResult>> { let mut rng = PecosRng::seed_from_u64(seed); @@ -422,6 +432,8 @@ pub fn register_quantum_info_module(parent: &Bound<'_, PyModule>) -> PyResult<() parent.add_function(wrap_pyfunction!(process_fidelity, parent)?)?; parent.add_function(wrap_pyfunction!(average_gate_fidelity, parent)?)?; parent.add_function(wrap_pyfunction!(gate_error, parent)?)?; + parent.add_function(wrap_pyfunction!(pauli_channel_diamond_norm, parent)?)?; + parent.add_function(wrap_pyfunction!(pauli_channel_diamond_distance, parent)?)?; parent.add_function(wrap_pyfunction!(random_density_matrix, parent)?)?; parent.add_function(wrap_pyfunction!(random_quantum_channel, parent)?)?; @@ -438,6 +450,8 @@ pub fn register_quantum_info_module(parent: &Bound<'_, PyModule>) -> PyResult<() "process_fidelity", "average_gate_fidelity", "gate_error", + "pauli_channel_diamond_norm", + "pauli_channel_diamond_distance", "random_density_matrix", "random_quantum_channel", ] { diff --git a/python/quantum-pecos/src/pecos/quantum_info.py b/python/quantum-pecos/src/pecos/quantum_info.py index 5232b9aff..558eb6d31 100644 --- a/python/quantum-pecos/src/pecos/quantum_info.py +++ b/python/quantum-pecos/src/pecos/quantum_info.py @@ -14,6 +14,8 @@ Ptm, average_gate_fidelity, gate_error, + pauli_channel_diamond_distance, + pauli_channel_diamond_norm, process_fidelity, purity, random_density_matrix, @@ -29,6 +31,8 @@ "Ptm", "average_gate_fidelity", "gate_error", + "pauli_channel_diamond_distance", + "pauli_channel_diamond_norm", "process_fidelity", "purity", "random_density_matrix", diff --git a/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py b/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py index dae4ce1bc..3519d455e 100644 --- a/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py +++ b/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py @@ -6,6 +6,8 @@ Ptm, average_gate_fidelity, gate_error, + pauli_channel_diamond_distance, + pauli_channel_diamond_norm, process_fidelity, purity, random_density_matrix, @@ -38,6 +40,10 @@ def test_pauli_channel_exposes_probabilities_and_ptm() -> None: assert ptm.num_qubits() == 1 assert_close(ptm.entry(0, 0), 1.0) + other = PauliChannel.one_qubit(0.0, 0.2, 0.3) + assert_close(pauli_channel_diamond_norm(channel, other), 0.6) + assert_close(pauli_channel_diamond_distance(channel, other), 0.3) + def test_choi_and_kraus_wrappers_round_trip_identity_channel() -> None: identity = Ptm.identity(1) From 49adbb799e48bbbecc06d111259f99ecc0c7fe92 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 00:52:34 -0600 Subject: [PATCH 082/125] Add simulator state conversion bridges --- crates/pecos-simulators/src/density_matrix.rs | 125 ++++++++++++++++++ 1 file changed, 125 insertions(+) diff --git a/crates/pecos-simulators/src/density_matrix.rs b/crates/pecos-simulators/src/density_matrix.rs index dce74e0d2..6adbda50a 100644 --- a/crates/pecos-simulators/src/density_matrix.rs +++ b/crates/pecos-simulators/src/density_matrix.rs @@ -14,11 +14,35 @@ use super::arbitrary_rotation_gateable::ArbitraryRotationGateable; use super::clifford_gateable::{CliffordGateable, MeasurementResult}; use super::quantum_simulator::QuantumSimulator; use super::state_vec::StateVec; +use super::state_vec_soa::StateVecSoA; use pecos_core::{Angle64, QubitId, RngManageable}; use pecos_random::{PecosRng, Rng, RngExt, SeedableRng}; use core::fmt::{Debug, Display, Formatter, Write}; use num_complex::Complex64; +use std::error::Error; + +const PURE_STATE_TOLERANCE: f64 = 1e-10; + +/// Error returned when converting between simulator state representations. +#[derive(Clone, Debug, PartialEq)] +pub enum StateConversionError { + /// The density matrix is not rank-1 within the conversion tolerance. + MixedDensityMatrix { residual: f64 }, +} + +impl Display for StateConversionError { + fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result { + match self { + Self::MixedDensityMatrix { residual } => write!( + f, + "density matrix is not a pure state; reconstruction residual is {residual}" + ), + } + } +} + +impl Error for StateConversionError {} /// A quantum state simulator using the density matrix representation via the Choi-Jamiolkowski isomorphism /// @@ -838,6 +862,76 @@ where } } +impl From<&StateVecSoA> for DensityMatrix +where + R: Rng + SeedableRng + Debug + Clone, +{ + fn from(state: &StateVecSoA) -> Self { + let mut state = state.clone(); + let amplitudes = state.state(); + let dim = amplitudes.len(); + let num_physical_qubits = dim.trailing_zeros() as usize; + let mut purification = vec![Complex64::new(0.0, 0.0); dim * dim]; + + for (row, amplitude) in amplitudes.iter().enumerate() { + purification[row << num_physical_qubits] = *amplitude; + } + + Self { + num_physical_qubits, + state_vector: StateVec::from_state(&purification, state.rng().clone()), + } + } +} + +impl TryFrom<&DensityMatrix> for Vec +where + R: Rng + SeedableRng + Debug + Clone, +{ + type Error = StateConversionError; + + fn try_from(density_matrix: &DensityMatrix) -> Result { + let mut density_matrix = density_matrix.clone(); + let rho = density_matrix.get_density_matrix(); + pure_state_from_density_matrix(&rho) + } +} + +fn pure_state_from_density_matrix( + rho: &[Vec], +) -> Result, StateConversionError> { + let dim = rho.len(); + let (pivot, pivot_probability) = rho + .iter() + .enumerate() + .map(|(i, row)| (i, row[i].re.max(0.0))) + .max_by(|(_, left), (_, right)| left.total_cmp(right)) + .unwrap_or((0, 0.0)); + + if pivot_probability <= PURE_STATE_TOLERANCE { + return Err(StateConversionError::MixedDensityMatrix { residual: 1.0 }); + } + + let pivot_amplitude = pivot_probability.sqrt(); + let state: Vec = (0..dim) + .map(|row| rho[row][pivot] / pivot_amplitude) + .collect(); + + let mut residual = 0.0_f64; + for row in 0..dim { + for col in 0..dim { + let reconstructed = state[row] * state[col].conj(); + residual = residual.max((rho[row][col] - reconstructed).norm()); + } + } + + if residual > PURE_STATE_TOLERANCE { + return Err(StateConversionError::MixedDensityMatrix { residual }); + } + + Ok(state) +} + impl Display for DensityMatrix where R: Rng + SeedableRng + Debug + Clone, @@ -1322,5 +1416,36 @@ mod tests { assert!(dm.is_pure()); } + #[test] + fn state_vector_converts_to_density_matrix_and_back() { + let mut state = StateVecSoA::new(2); + state.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); + + let mut density_matrix = DensityMatrix::from(&state); + assert!((density_matrix.probability(0) - 0.5).abs() < 1e-10); + assert!(density_matrix.probability(1) < 1e-10); + assert!(density_matrix.probability(2) < 1e-10); + assert!((density_matrix.probability(3) - 0.5).abs() < 1e-10); + + let recovered = Vec::::try_from(&density_matrix).unwrap(); + let expected = state.state(); + + for (actual, expected) in recovered.iter().zip(expected.iter()) { + assert!((*actual - *expected).norm() < 1e-10); + } + } + + #[test] + fn mixed_density_matrix_rejects_state_vector_conversion() { + let mut density_matrix = DensityMatrix::new(1); + density_matrix.prepare_maximally_mixed(); + + let err = Vec::::try_from(&density_matrix).unwrap_err(); + assert!(matches!( + err, + StateConversionError::MixedDensityMatrix { .. } + )); + } + // Additional tests for other gates and operations would be added here } From 94dab46178d9f0799fd1aa119b33d073f08f31cc Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 00:56:03 -0600 Subject: [PATCH 083/125] Add quantum information measure utilities --- crates/pecos-quantum/src/lib.rs | 7 +- crates/pecos-quantum/src/measures.rs | 369 ++++++++++++++++++++++++++- 2 files changed, 369 insertions(+), 7 deletions(-) diff --git a/crates/pecos-quantum/src/lib.rs b/crates/pecos-quantum/src/lib.rs index 41dd803c5..dd18f52da 100644 --- a/crates/pecos-quantum/src/lib.rs +++ b/crates/pecos-quantum/src/lib.rs @@ -115,9 +115,10 @@ pub use diamond_norm::{ }; pub use measures::{ DensityMatrixPartialTrace, MeasureError, average_gate_fidelity, concurrence, - entanglement_of_formation, entropy, entropy_with_base, gate_error, mutual_information, - partial_trace_qubits, partial_trace_subsystems, process_fidelity, purity, state_fidelity, - state_fidelity_with_density_matrix, + entanglement_of_formation, entropy, entropy_with_base, gate_error, hellinger_distance, + hellinger_fidelity, logarithmic_negativity, mutual_information, negativity, + partial_trace_qubits, partial_trace_subsystems, process_fidelity, purity, + schmidt_decomposition, shannon_entropy, state_fidelity, state_fidelity_with_density_matrix, }; // Re-export operator matrix types for convenient method-style matrix conversion diff --git a/crates/pecos-quantum/src/measures.rs b/crates/pecos-quantum/src/measures.rs index 1868f5073..d063e554b 100644 --- a/crates/pecos-quantum/src/measures.rs +++ b/crates/pecos-quantum/src/measures.rs @@ -95,6 +95,20 @@ pub enum MeasureError { /// Invalid base. base: f64, }, + /// A probability is negative or non-finite. + InvalidProbability { + /// Index of the invalid probability. + index: usize, + /// Invalid probability value. + probability: f64, + }, + /// A probability distribution does not sum to one. + InvalidProbabilitySum { + /// Observed probability sum. + sum: f64, + /// Allowed absolute tolerance. + tolerance: f64, + }, /// Subsystem dimensions are invalid for a multipartite measure. InvalidSubsystemDimensions { /// Subsystem dimensions supplied by the caller. @@ -170,6 +184,14 @@ impl fmt::Display for MeasureError { "entropy logarithm base must be finite, positive, and not 1; got {base}" ) } + Self::InvalidProbability { index, probability } => write!( + f, + "probability at index {index} must be finite and non-negative, got {probability}" + ), + Self::InvalidProbabilitySum { sum, tolerance } => write!( + f, + "probability distribution must sum to 1 within tolerance {tolerance}, got {sum}" + ), Self::InvalidSubsystemDimensions { dims, matrix_dim } => write!( f, "invalid subsystem dimensions {dims:?} for density matrix dimension {matrix_dim}" @@ -352,13 +374,36 @@ pub fn entropy_with_base(rho: &DMatrix, base: f64) -> Result Result { + validate_entropy_base(base)?; + validate_probability_distribution(probabilities)?; let log_base = base.ln(); - Ok(svd - .singular_values + Ok(probabilities .iter() .copied() - .filter(|lambda| *lambda > DEFAULT_TOLERANCE) - .map(|lambda| -lambda * lambda.ln() / log_base) + .filter(|probability| *probability > DEFAULT_TOLERANCE) + .map(|probability| -probability * probability.ln() / log_base) .sum()) } @@ -475,6 +520,98 @@ pub fn entanglement_of_formation(rho: &DMatrix) -> Result, + dims: &[usize], + subsystem: usize, +) -> Result { + let partial_transpose = partial_transpose_subsystem(rho, dims, subsystem)?; + let trace_norm: f64 = SVD::new(partial_transpose, false, false) + .singular_values + .iter() + .sum(); + Ok(((trace_norm - 1.0) / 2.0).max(0.0)) +} + +/// Returns logarithmic negativity `log2(2 * negativity + 1)`. +/// +/// # Errors +/// +/// Returns an error when [`negativity`] fails. +pub fn logarithmic_negativity( + rho: &DMatrix, + dims: &[usize], + subsystem: usize, +) -> Result { + Ok((2.0 * negativity(rho, dims, subsystem)? + 1.0).log2()) +} + +/// Returns the Schmidt decomposition of a pure state across a bipartition. +/// +/// `dims[i]` is the dimension of subsystem `i`; subsystem 0 is the +/// fastest-varying factor. `left_subsystems` selects the left side of the +/// bipartition. The right side is the sorted complement. Returned terms are +/// `(coefficient, left_vector, right_vector)` and omit numerically-zero +/// coefficients. +/// +/// # Errors +/// +/// Returns an error when the state is not normalized, when `dims` do not match +/// the state-vector length, or when `left_subsystems` contains an invalid or +/// repeated subsystem. +pub fn schmidt_decomposition( + state: &DVector, + dims: &[usize], + left_subsystems: &[usize], +) -> Result, Vec)>, MeasureError> { + validate_state_vector(state)?; + validate_state_subsystem_dimensions(state.len(), dims)?; + let left = validated_sorted_subsystems(dims, left_subsystems)?; + let right: Vec = (0..dims.len()) + .filter(|subsystem| left.binary_search(subsystem).is_err()) + .collect(); + let left_dim = subsystem_product(dims, &left)?; + let right_dim = subsystem_product(dims, &right)?; + let strides = subsystem_strides(dims)?; + + let mut matrix = DMatrix::zeros(left_dim, right_dim); + for basis_index in 0..state.len() { + let left_index = project_subsystem_index(dims, &strides, &left, basis_index); + let right_index = project_subsystem_index(dims, &strides, &right, basis_index); + matrix[(left_index, right_index)] = state[basis_index]; + } + + let svd = SVD::new(matrix, true, true); + let left_vectors = svd.u.ok_or(MeasureError::EigenDecompositionFailed)?; + let right_vectors_adjoint = svd.v_t.ok_or(MeasureError::EigenDecompositionFailed)?; + + Ok(svd + .singular_values + .iter() + .enumerate() + .filter(|(_, coefficient)| **coefficient > DEFAULT_TOLERANCE) + .map(|(idx, &coefficient)| { + let left_vector = left_vectors.column(idx).iter().copied().collect(); + let right_vector = right_vectors_adjoint + .row(idx) + .iter() + .map(|value| value.conj()) + .collect(); + (coefficient, left_vector, right_vector) + }) + .collect()) +} + /// Returns the reduced density matrix after tracing out selected subsystems. /// /// `dims[i]` is the Hilbert-space dimension of subsystem `i`. Subsystem 0 is @@ -592,6 +729,44 @@ pub fn mutual_information( Ok(entropy(&rho_a)? + entropy(&rho_b)? - entropy(rho)?) } +/// Returns the Hellinger distance between classical probability distributions. +/// +/// `H(p, q) = sqrt(1 - sum_i sqrt(p_i q_i))`. +/// +/// # Errors +/// +/// Returns an error when the vectors have different lengths or either vector is +/// not a probability distribution. +pub fn hellinger_distance(left: &[f64], right: &[f64]) -> Result { + if left.len() != right.len() { + return Err(MeasureError::VectorLengthMismatch { + left: left.len(), + right: right.len(), + }); + } + validate_probability_distribution(left)?; + validate_probability_distribution(right)?; + let affinity: f64 = left + .iter() + .zip(right.iter()) + .map(|(&left, &right)| (left * right).sqrt()) + .sum(); + Ok((1.0 - affinity.clamp(0.0, 1.0)).sqrt()) +} + +/// Returns Hellinger fidelity between classical probability distributions. +/// +/// The value is `(1 - H(p, q)^2)^2`, where `H` is +/// [`hellinger_distance`]. +/// +/// # Errors +/// +/// Returns an error when [`hellinger_distance`] fails. +pub fn hellinger_fidelity(left: &[f64], right: &[f64]) -> Result { + let distance = hellinger_distance(left, right)?; + Ok((1.0 - distance * distance).powi(2)) +} + fn validate_state_vector(vector: &DVector) -> Result<(), MeasureError> { let mut norm_sqr = 0.0; for value in vector.iter() { @@ -658,6 +833,23 @@ fn validate_entropy_base(base: f64) -> Result<(), MeasureError> { } } +fn validate_probability_distribution(probabilities: &[f64]) -> Result<(), MeasureError> { + let mut sum = 0.0; + for (index, &probability) in probabilities.iter().enumerate() { + if !probability.is_finite() || probability < -DEFAULT_TOLERANCE { + return Err(MeasureError::InvalidProbability { index, probability }); + } + sum += probability.max(0.0); + } + if (sum - 1.0).abs() > DEFAULT_TOLERANCE { + return Err(MeasureError::InvalidProbabilitySum { + sum, + tolerance: DEFAULT_TOLERANCE, + }); + } + Ok(()) +} + fn trace(matrix: &DMatrix) -> Complex64 { let n = matrix.nrows().min(matrix.ncols()); (0..n).map(|idx| matrix[(idx, idx)]).sum() @@ -727,6 +919,58 @@ fn validate_subsystem_dimensions( } } +fn validate_state_subsystem_dimensions( + state_len: usize, + dims: &[usize], +) -> Result<(), MeasureError> { + let Some(total_dim) = + dims.iter().try_fold( + 1usize, + |acc, &dim| { + if dim == 0 { None } else { acc.checked_mul(dim) } + }, + ) + else { + return Err(MeasureError::InvalidSubsystemDimensions { + dims: dims.to_vec(), + matrix_dim: state_len, + }); + }; + + if state_len == total_dim { + Ok(()) + } else { + Err(MeasureError::InvalidSubsystemDimensions { + dims: dims.to_vec(), + matrix_dim: state_len, + }) + } +} + +fn validated_sorted_subsystems( + dims: &[usize], + subsystems: &[usize], +) -> Result, MeasureError> { + let mut sorted = subsystems.to_vec(); + sorted.sort_unstable(); + for window in sorted.windows(2) { + if window[0] == window[1] { + return Err(MeasureError::DuplicateSubsystem { + subsystem: window[0], + }); + } + } + for &subsystem in &sorted { + if subsystem >= dims.len() { + return Err(MeasureError::SubsystemOutOfRange { + num_subsystems: dims.len(), + subsystem, + }); + } + } + Ok(sorted) +} + fn subsystem_product(dims: &[usize], subsystems: &[usize]) -> Result { subsystems.iter().try_fold(1usize, |acc, &subsystem| { acc.checked_mul(dims[subsystem]) @@ -777,6 +1021,52 @@ fn embed_subsystem_index( index } +fn project_subsystem_index( + dims: &[usize], + strides: &[usize], + subsystems: &[usize], + basis_index: usize, +) -> usize { + let mut out = 0usize; + let mut out_stride = 1usize; + for &subsystem in subsystems { + let coord = (basis_index / strides[subsystem]) % dims[subsystem]; + out += coord * out_stride; + out_stride *= dims[subsystem]; + } + out +} + +fn partial_transpose_subsystem( + rho: &DMatrix, + dims: &[usize], + subsystem: usize, +) -> Result, MeasureError> { + validate_density_matrix(rho)?; + validate_subsystem_dimensions(rho, dims)?; + if subsystem >= dims.len() { + return Err(MeasureError::SubsystemOutOfRange { + num_subsystems: dims.len(), + subsystem, + }); + } + + let strides = subsystem_strides(dims)?; + let mut out = DMatrix::zeros(rho.nrows(), rho.ncols()); + for row in 0..rho.nrows() { + for col in 0..rho.ncols() { + let row_coord = (row / strides[subsystem]) % dims[subsystem]; + let col_coord = (col / strides[subsystem]) % dims[subsystem]; + let transposed_row = + row - row_coord * strides[subsystem] + col_coord * strides[subsystem]; + let transposed_col = + col - col_coord * strides[subsystem] + row_coord * strides[subsystem]; + out[(transposed_row, transposed_col)] = rho[(row, col)]; + } + } + Ok(out) +} + fn binary_entropy(probability: f64) -> f64 { let p = probability.clamp(0.0, 1.0); if p <= DEFAULT_TOLERANCE || (1.0 - p) <= DEFAULT_TOLERANCE { @@ -898,6 +1188,52 @@ mod tests { assert_close(mutual_information(&product, (2, 2)).unwrap(), 0.0); } + #[test] + fn negativity_matches_bell_and_product_states() { + let bell = ket(&[ + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + ]); + let bell_rho = pure_density(&bell); + assert_close(negativity(&bell_rho, &[2, 2], 1).unwrap(), 0.5); + assert_close(logarithmic_negativity(&bell_rho, &[2, 2], 1).unwrap(), 1.0); + + let product = pure_density(&ket(&[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + ])); + assert_close(negativity(&product, &[2, 2], 1).unwrap(), 0.0); + assert_close(logarithmic_negativity(&product, &[2, 2], 1).unwrap(), 0.0); + } + + #[test] + fn schmidt_decomposition_matches_bell_and_product_states() { + let bell = ket(&[ + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + ]); + let bell_terms = schmidt_decomposition(&bell, &[2, 2], &[0]).unwrap(); + assert_eq!(bell_terms.len(), 2); + assert_close(bell_terms[0].0, 1.0 / 2.0_f64.sqrt()); + assert_close(bell_terms[1].0, 1.0 / 2.0_f64.sqrt()); + + let product = ket(&[ + Complex64::new(1.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + ]); + let product_terms = schmidt_decomposition(&product, &[2, 2], &[0]).unwrap(); + assert_eq!(product_terms.len(), 1); + assert_close(product_terms[0].0, 1.0); + } + #[test] fn mutual_information_accepts_non_qubit_subsystem_dims() { let mut rho = DMatrix::zeros(6, 6); @@ -907,6 +1243,31 @@ mod tests { assert_close(mutual_information(&rho, (2, 3)).unwrap(), 1.0); } + #[test] + fn shannon_entropy_is_public_distribution_entropy() { + assert_close(shannon_entropy(&[0.5, 0.5], 2.0).unwrap(), 1.0); + assert_close(shannon_entropy(&[1.0, 0.0], 2.0).unwrap(), 0.0); + assert!(matches!( + shannon_entropy(&[0.25, 0.25], 2.0).unwrap_err(), + MeasureError::InvalidProbabilitySum { .. } + )); + } + + #[test] + fn hellinger_distance_and_fidelity_match_classical_cases() { + assert_close( + hellinger_distance(&[0.25, 0.75], &[0.25, 0.75]).unwrap(), + 0.0, + ); + assert_close( + hellinger_fidelity(&[0.25, 0.75], &[0.25, 0.75]).unwrap(), + 1.0, + ); + + assert_close(hellinger_distance(&[1.0, 0.0], &[0.0, 1.0]).unwrap(), 1.0); + assert_close(hellinger_fidelity(&[1.0, 0.0], &[0.0, 1.0]).unwrap(), 0.0); + } + #[test] fn partial_trace_supports_method_and_qubit_forms() { let bell = ket(&[ From f3c73645cc79338fcb591ab5fe5dbbbf57edbde5 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 00:57:38 -0600 Subject: [PATCH 084/125] Group commuting Pauli collections --- crates/pecos-quantum/src/channel.rs | 70 ++++++++++++++++++++++ crates/pecos-quantum/src/pauli_sequence.rs | 47 +++++++++++++++ 2 files changed, 117 insertions(+) diff --git a/crates/pecos-quantum/src/channel.rs b/crates/pecos-quantum/src/channel.rs index 4aa0923cb..22fc8d58e 100644 --- a/crates/pecos-quantum/src/channel.rs +++ b/crates/pecos-quantum/src/channel.rs @@ -526,6 +526,34 @@ impl PauliSum { self } + /// Greedily partitions terms into mutually commuting sums. + /// + /// Coefficients are preserved exactly. The grouping is a graph-coloring + /// heuristic on the anticommutation graph, so it is not guaranteed to use + /// the minimum possible number of groups. + #[must_use] + pub fn group_commuting(&self) -> Vec { + let mut groups: Vec> = Vec::new(); + + 'next_term: for (pauli, coefficient) in &self.terms { + for group in &mut groups { + if group.keys().all(|other| pauli.commutes_with(other)) { + group.insert(pauli.clone(), *coefficient); + continue 'next_term; + } + } + groups.push(BTreeMap::from([(pauli.clone(), *coefficient)])); + } + + groups + .into_iter() + .map(|terms| Self { + num_qubits: self.num_qubits, + terms, + }) + .collect() + } + /// Returns the Pauli conjugation `P * self * P†`. /// /// Pauli conjugation preserves each Pauli label and flips the coefficient @@ -2475,6 +2503,48 @@ mod tests { ); } + #[test] + fn pauli_sum_group_commuting_preserves_coefficients() { + let mut sum = PauliSum::new(2); + sum.add_term(PauliBitmaskSmall::x(0), Complex64::new(2.0, 0.0)) + .unwrap(); + sum.add_term(PauliBitmaskSmall::z(0), Complex64::new(3.0, 0.0)) + .unwrap(); + sum.add_term(PauliBitmaskSmall::x(1), Complex64::new(5.0, 0.0)) + .unwrap(); + sum.add_term(PauliBitmaskSmall::z(1), Complex64::new(7.0, 0.0)) + .unwrap(); + + let groups = sum.group_commuting(); + assert_eq!(groups.len(), 2); + assert_eq!( + groups + .iter() + .map(|group| group.terms().len()) + .sum::(), + 4 + ); + + for group in &groups { + for left in group.terms().keys() { + for right in group.terms().keys() { + assert!(left.commutes_with(right)); + } + } + } + + let recovered: BTreeMap<_, _> = groups + .iter() + .flat_map(|group| { + group + .terms() + .iter() + .map(|(pauli, coeff)| (pauli.clone(), *coeff)) + }) + .collect(); + assert_eq!(recovered, sum.terms().clone()); + } + #[test] fn qubit_count_errors_fail_construction() { let mut terms = BTreeMap::new(); diff --git a/crates/pecos-quantum/src/pauli_sequence.rs b/crates/pecos-quantum/src/pauli_sequence.rs index dd9dd3d0f..2c4ac0e3b 100644 --- a/crates/pecos-quantum/src/pauli_sequence.rs +++ b/crates/pecos-quantum/src/pauli_sequence.rs @@ -816,6 +816,42 @@ impl PauliSequence { matrix } + /// Greedily partitions the sequence into mutually commuting groups. + /// + /// The returned groups preserve the input order within each group. This is + /// a graph-coloring heuristic on the anticommutation graph, so it is not + /// guaranteed to produce the minimum possible number of groups. + #[must_use] + pub fn group_commuting(&self) -> Vec { + let anticommutation = self.commutation_matrix(); + let mut groups: Vec> = Vec::new(); + + 'next_pauli: for pauli_idx in 0..self.paulis.len() { + for group in &mut groups { + if group + .iter() + .all(|&other_idx| anticommutation.get(pauli_idx, other_idx) == 0) + { + group.push(pauli_idx); + continue 'next_pauli; + } + } + groups.push(vec![pauli_idx]); + } + + groups + .into_iter() + .map(|group| { + PauliSequence::new( + group + .into_iter() + .map(|idx| self.paulis[idx].clone()) + .collect(), + ) + }) + .collect() + } + /// Returns the sequence in row-reduced form. /// /// This returns a new `PauliSequence` where the Pauli strings are independent @@ -1192,6 +1228,17 @@ mod tests { } } + #[test] + fn group_commuting_partitions_into_abelian_sequences() { + let gens = PauliSequence::new(vec![X(0), Z(0), X(1), Z(1)]); + let groups = gens.group_commuting(); + + assert_eq!(groups.len(), 2); + assert_eq!(groups[0].paulis(), &[X(0), X(1)]); + assert_eq!(groups[1].paulis(), &[Z(0), Z(1)]); + assert!(groups.iter().all(PauliSequence::is_abelian)); + } + #[test] fn test_row_reduce() { // ZIZ = ZZI * IZZ, so one generator is redundant From 69869a2595b1759a8843b9d9163f372a0d9d6d99 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 01:03:42 -0600 Subject: [PATCH 085/125] Add channel matrix representation types --- crates/pecos-quantum/src/channel.rs | 629 +++++++++++++++++++++++++++ crates/pecos-quantum/src/lib.rs | 13 +- crates/pecos-quantum/src/measures.rs | 8 +- 3 files changed, 643 insertions(+), 7 deletions(-) diff --git a/crates/pecos-quantum/src/channel.rs b/crates/pecos-quantum/src/channel.rs index 22fc8d58e..52cf74006 100644 --- a/crates/pecos-quantum/src/channel.rs +++ b/crates/pecos-quantum/src/channel.rs @@ -20,6 +20,9 @@ //! - [`Ptm`] stores a dense real Pauli-transfer matrix. //! - [`KrausOps`] stores a concrete Kraus-operator channel representation. //! - [`ChoiMatrix`] stores a concrete Choi representation. +//! - [`SuperOp`] stores a dense column-stacked superoperator. +//! - [`ChiMatrix`] stores a process matrix in the Pauli basis. +//! - [`Stinespring`] stores a Stinespring isometry. //! //! Pauli-channel probabilities and diagonal PTM entries are connected by an //! explicit Walsh-Hadamard transform. They are not the same representation: @@ -1187,6 +1190,24 @@ impl Ptm { pub fn to_kraus(&self) -> Result { self.to_choi()?.to_kraus() } + + /// Converts this PTM to a column-stacked superoperator. + /// + /// # Errors + /// + /// Returns an error when the conversion through matrix units fails. + pub fn to_superop(&self) -> Result { + SuperOp::from_ptm(self) + } + + /// Converts this PTM to a Pauli-basis process matrix. + /// + /// # Errors + /// + /// Returns an error when the conversion through Choi/Kraus form fails. + pub fn to_chi(&self) -> Result { + ChiMatrix::from_ptm(self) + } } /// Concrete Kraus-operator representation of a quantum channel. @@ -1298,6 +1319,33 @@ impl KrausOps { ChoiMatrix::from_kraus(self) } + /// Converts this Kraus channel to a column-stacked superoperator. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn to_superop(&self) -> Result { + SuperOp::from_kraus(self) + } + + /// Converts this Kraus channel to a Pauli-basis process matrix. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn to_chi(&self) -> Result { + ChiMatrix::from_kraus(self) + } + + /// Converts this Kraus channel to a Stinespring isometry. + /// + /// # Errors + /// + /// Returns an error when the stacked Kraus operators are not an isometry. + pub fn to_stinespring(&self) -> Result { + Stinespring::from_kraus(self) + } + /// Returns whether `sum_k K_k† K_k = I` within the default tolerance. #[must_use] pub fn is_trace_preserving(&self) -> bool { @@ -1526,6 +1574,24 @@ impl ChoiMatrix { self.to_kraus_with_tolerance(DEFAULT_TOLERANCE) } + /// Converts this Choi matrix to a column-stacked superoperator. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn to_superop(&self) -> Result { + SuperOp::from_choi(self) + } + + /// Converts this Choi matrix to a Pauli-basis process matrix. + /// + /// # Errors + /// + /// Returns an error when conversion through Kraus form fails. + pub fn to_chi(&self) -> Result { + ChiMatrix::from_choi(self) + } + /// Converts this Choi matrix to Kraus operators with an explicit /// singular-value cutoff. /// @@ -1740,6 +1806,470 @@ impl ChoiMatrix { } } +/// Dense column-stacked superoperator representation. +/// +/// `SuperOp` stores the matrix `S` satisfying `vec(E(A)) = S vec(A)`, where +/// `vec` uses column-stacking in PECOS's little-endian computational basis. +#[derive(Clone, Debug, PartialEq)] +pub struct SuperOp { + num_qubits: usize, + matrix: DMatrix, +} + +impl SuperOp { + /// Constructs a superoperator after structural validation. + /// + /// # Errors + /// + /// Returns an error when `matrix` is not `4^n x 4^n` or contains + /// non-finite entries. + pub fn try_new(num_qubits: usize, matrix: DMatrix) -> Result { + let dim_squared = pauli_basis_len(num_qubits)?; + validate_complex_matrix(&matrix, dim_squared, dim_squared)?; + Ok(Self { num_qubits, matrix }) + } + + /// Constructs a superoperator from Kraus operators. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn from_kraus(kraus: &KrausOps) -> Result { + let dim = hilbert_dim(kraus.num_qubits)?; + let dim_squared = pauli_basis_len(kraus.num_qubits)?; + let mut matrix = DMatrix::zeros(dim_squared, dim_squared); + for input_col in 0..dim { + for input_row in 0..dim { + let input_idx = matrix_unit_index(dim, input_row, input_col); + for output_col in 0..dim { + for output_row in 0..dim { + let output_idx = matrix_unit_index(dim, output_row, output_col); + let mut value = Complex64::new(0.0, 0.0); + for operator in kraus.operators() { + value += operator[(output_row, input_row)] + * operator[(output_col, input_col)].conj(); + } + matrix[(output_idx, input_idx)] = value; + } + } + } + } + Self::try_new(kraus.num_qubits, matrix) + } + + /// Constructs a superoperator from a Choi matrix. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn from_choi(choi: &ChoiMatrix) -> Result { + let dim = hilbert_dim(choi.num_qubits)?; + let dim_squared = pauli_basis_len(choi.num_qubits)?; + let mut matrix = DMatrix::zeros(dim_squared, dim_squared); + for input_col in 0..dim { + for input_row in 0..dim { + let input_idx = matrix_unit_index(dim, input_row, input_col); + for output_col in 0..dim { + for output_row in 0..dim { + let output_idx = matrix_unit_index(dim, output_row, output_col); + matrix[(output_idx, input_idx)] = choi.matrix()[( + choi_index(dim, output_row, input_row), + choi_index(dim, output_col, input_col), + )]; + } + } + } + } + Self::try_new(choi.num_qubits, matrix) + } + + /// Constructs a superoperator from a PTM. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn from_ptm(ptm: &Ptm) -> Result { + let dim = hilbert_dim(ptm.num_qubits)?; + let dim_squared = pauli_basis_len(ptm.num_qubits)?; + let mut matrix = DMatrix::zeros(dim_squared, dim_squared); + for input_col in 0..dim { + for input_row in 0..dim { + let mut input = DMatrix::zeros(dim, dim); + input[(input_row, input_col)] = Complex64::new(1.0, 0.0); + let output = apply_ptm_to_operator(ptm, &input)?; + let input_idx = matrix_unit_index(dim, input_row, input_col); + for output_col in 0..dim { + for output_row in 0..dim { + let output_idx = matrix_unit_index(dim, output_row, output_col); + matrix[(output_idx, input_idx)] = output[(output_row, output_col)]; + } + } + } + } + Self::try_new(ptm.num_qubits, matrix) + } + + /// Constructs a superoperator from a supported channel expression. + /// + /// # Errors + /// + /// Returns an error when the expression cannot be represented as Kraus + /// operators. + pub fn from_channel_expr(channel: &ChannelExpr) -> Result { + KrausOps::from_channel_expr(channel)?.to_superop() + } + + /// Converts this superoperator to a Choi matrix. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn to_choi(&self) -> Result { + let dim = hilbert_dim(self.num_qubits)?; + let mut matrix = DMatrix::zeros(self.matrix.nrows(), self.matrix.ncols()); + for input_col in 0..dim { + for input_row in 0..dim { + let input_idx = matrix_unit_index(dim, input_row, input_col); + for output_col in 0..dim { + for output_row in 0..dim { + let output_idx = matrix_unit_index(dim, output_row, output_col); + matrix[( + choi_index(dim, output_row, input_row), + choi_index(dim, output_col, input_col), + )] = self.matrix[(output_idx, input_idx)]; + } + } + } + } + ChoiMatrix::try_new(self.num_qubits, matrix) + } + + /// Converts this superoperator to a PTM. + /// + /// # Errors + /// + /// Returns an error when Choi/PTM conversion fails. + pub fn to_ptm(&self) -> Result { + self.to_choi()?.to_ptm() + } + + /// Converts this superoperator to Kraus operators. + /// + /// # Errors + /// + /// Returns an error when Choi/Kraus conversion fails. + pub fn to_kraus(&self) -> Result { + self.to_choi()?.to_kraus() + } + + /// Returns the composition `self ∘ other`, applying `other` first. + /// + /// # Errors + /// + /// Returns an error when qubit counts differ. + pub fn compose(&self, other: &Self) -> Result { + if self.num_qubits != other.num_qubits { + return Err(ChannelError::InvalidMatrixShape { + expected_rows: self.matrix.nrows(), + expected_cols: self.matrix.ncols(), + rows: other.matrix.nrows(), + cols: other.matrix.ncols(), + }); + } + Self::try_new(self.num_qubits, &self.matrix * &other.matrix) + } + + /// Returns the tensor product of two superoperators. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn tensor(&self, other: &Self) -> Result { + Self::try_new( + self.num_qubits + other.num_qubits, + complex_kronecker(&self.matrix, &other.matrix), + ) + } + + /// Returns the number of qubits represented by this superoperator. + #[must_use] + pub fn num_qubits(&self) -> usize { + self.num_qubits + } + + /// Returns the dense superoperator matrix. + #[must_use] + pub fn matrix(&self) -> &DMatrix { + &self.matrix + } + + /// Consumes this value and returns its dense matrix. + #[must_use] + pub fn into_matrix(self) -> DMatrix { + self.matrix + } +} + +/// Pauli-basis process matrix. +/// +/// `ChiMatrix` stores coefficients `chi_ij` in +/// `E(rho) = sum_ij chi_ij P_i rho P_j†`, with the same Pauli basis ordering +/// as [`Ptm`]. +#[derive(Clone, Debug, PartialEq)] +pub struct ChiMatrix { + num_qubits: usize, + basis_order: PtmBasisOrder, + matrix: DMatrix, +} + +impl ChiMatrix { + /// Constructs a chi matrix after structural validation. + /// + /// # Errors + /// + /// Returns an error when `matrix` is not `4^n x 4^n` or contains + /// non-finite entries. + pub fn try_new(num_qubits: usize, matrix: DMatrix) -> Result { + let basis_len = pauli_basis_len(num_qubits)?; + validate_complex_matrix(&matrix, basis_len, basis_len)?; + Ok(Self { + num_qubits, + basis_order: PtmBasisOrder::default(), + matrix, + }) + } + + /// Constructs a chi matrix from Kraus operators. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn from_kraus(kraus: &KrausOps) -> Result { + let basis_len = pauli_basis_len(kraus.num_qubits)?; + let dim = hilbert_dim(kraus.num_qubits)?; + #[allow(clippy::cast_precision_loss)] + let dim_f = dim as f64; + let basis = pauli_basis_matrices(kraus.num_qubits)?; + let mut matrix = DMatrix::zeros(basis_len, basis_len); + for operator in kraus.operators() { + let coefficients: Vec = basis + .iter() + .map(|pauli| trace_complex(&(pauli * operator)) / dim_f) + .collect(); + for row in 0..basis_len { + for col in 0..basis_len { + matrix[(row, col)] += coefficients[row] * coefficients[col].conj(); + } + } + } + Self::try_new(kraus.num_qubits, matrix) + } + + /// Constructs a chi matrix from a Choi matrix. + /// + /// # Errors + /// + /// Returns an error when Choi/Kraus conversion fails. + pub fn from_choi(choi: &ChoiMatrix) -> Result { + choi.to_kraus()?.to_chi() + } + + /// Constructs a chi matrix from a PTM. + /// + /// # Errors + /// + /// Returns an error when PTM/Choi/Kraus conversion fails. + pub fn from_ptm(ptm: &Ptm) -> Result { + ptm.to_kraus()?.to_chi() + } + + /// Constructs a chi matrix from a supported channel expression. + /// + /// # Errors + /// + /// Returns an error when the expression cannot be represented as Kraus + /// operators. + pub fn from_channel_expr(channel: &ChannelExpr) -> Result { + KrausOps::from_channel_expr(channel)?.to_chi() + } + + /// Converts this chi matrix to a Choi matrix. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn to_choi(&self) -> Result { + let dim_squared = pauli_basis_len(self.num_qubits)?; + let basis = pauli_basis_matrices(self.num_qubits)?; + let basis_vectors: Vec> = basis.iter().map(vectorize_matrix).collect(); + let mut matrix = DMatrix::zeros(dim_squared, dim_squared); + for row in 0..dim_squared { + for col in 0..dim_squared { + let coefficient = self.matrix[(row, col)]; + if coefficient.norm() <= DEFAULT_TOLERANCE { + continue; + } + matrix += &basis_vectors[row] * basis_vectors[col].adjoint() * coefficient; + } + } + ChoiMatrix::try_new(self.num_qubits, matrix) + } + + /// Converts this chi matrix to a PTM. + /// + /// # Errors + /// + /// Returns an error when Choi/PTM conversion fails. + pub fn to_ptm(&self) -> Result { + self.to_choi()?.to_ptm() + } + + /// Returns the number of qubits represented by this chi matrix. + #[must_use] + pub fn num_qubits(&self) -> usize { + self.num_qubits + } + + /// Returns the PTM basis ordering. + #[must_use] + pub fn basis_order(&self) -> PtmBasisOrder { + self.basis_order + } + + /// Returns the dense chi matrix. + #[must_use] + pub fn matrix(&self) -> &DMatrix { + &self.matrix + } + + /// Consumes this value and returns its dense matrix. + #[must_use] + pub fn into_matrix(self) -> DMatrix { + self.matrix + } +} + +/// Stinespring isometry representation of a quantum channel. +/// +/// The matrix has shape `(num_kraus * d) x d` and stacks Kraus operators +/// vertically, where `d = 2^num_qubits`. +#[derive(Clone, Debug, PartialEq)] +pub struct Stinespring { + num_qubits: usize, + environment_dim: usize, + isometry: DMatrix, +} + +impl Stinespring { + /// Constructs a Stinespring isometry after structural validation. + /// + /// # Errors + /// + /// Returns an error when shape or isometry validation fails. + pub fn try_new(num_qubits: usize, isometry: DMatrix) -> Result { + let dim = hilbert_dim(num_qubits)?; + if isometry.ncols() != dim || isometry.nrows() == 0 || !isometry.nrows().is_multiple_of(dim) + { + return Err(ChannelError::InvalidMatrixShape { + expected_rows: dim, + expected_cols: dim, + rows: isometry.nrows(), + cols: isometry.ncols(), + }); + } + validate_complex_matrix(&isometry, isometry.nrows(), dim)?; + let identity = DMatrix::::identity(dim, dim); + let gram = isometry.adjoint() * &isometry; + if matrix_max_abs_diff(&gram, &identity) > 1e-10 { + return Err(ChannelError::DecompositionFailed { + reason: "Stinespring matrix is not an isometry".to_string(), + }); + } + Ok(Self { + num_qubits, + environment_dim: isometry.nrows() / dim, + isometry, + }) + } + + /// Constructs a Stinespring isometry by stacking Kraus operators. + /// + /// # Errors + /// + /// Returns an error when the Kraus operators are not trace preserving. + pub fn from_kraus(kraus: &KrausOps) -> Result { + let dim = hilbert_dim(kraus.num_qubits)?; + let mut isometry = DMatrix::zeros(dim * kraus.operators().len(), dim); + for (kraus_idx, operator) in kraus.operators().iter().enumerate() { + for row in 0..dim { + for col in 0..dim { + isometry[(kraus_idx * dim + row, col)] = operator[(row, col)]; + } + } + } + Self::try_new(kraus.num_qubits, isometry) + } + + /// Converts this Stinespring isometry to Kraus operators. + /// + /// # Errors + /// + /// Returns an error when dimensions overflow. + pub fn to_kraus(&self) -> Result { + let dim = hilbert_dim(self.num_qubits)?; + let operators = (0..self.environment_dim) + .map(|kraus_idx| { + DMatrix::from_fn(dim, dim, |row, col| { + self.isometry[(kraus_idx * dim + row, col)] + }) + }) + .collect(); + KrausOps::try_new(self.num_qubits, operators) + } + + /// Converts this Stinespring isometry to a Choi matrix. + /// + /// # Errors + /// + /// Returns an error when Kraus/Choi conversion fails. + pub fn to_choi(&self) -> Result { + self.to_kraus()?.to_choi() + } + + /// Converts this Stinespring isometry to a superoperator. + /// + /// # Errors + /// + /// Returns an error when Kraus/superoperator conversion fails. + pub fn to_superop(&self) -> Result { + self.to_kraus()?.to_superop() + } + + /// Returns the number of qubits represented by this isometry. + #[must_use] + pub fn num_qubits(&self) -> usize { + self.num_qubits + } + + /// Returns the environment dimension, equal to the number of Kraus blocks. + #[must_use] + pub fn environment_dim(&self) -> usize { + self.environment_dim + } + + /// Returns the dense Stinespring isometry. + #[must_use] + pub fn isometry(&self) -> &DMatrix { + &self.isometry + } + + /// Consumes this value and returns its dense isometry. + #[must_use] + pub fn into_isometry(self) -> DMatrix { + self.isometry + } +} + /// Returns the partial trace of a density matrix over selected qubits. /// /// Qubit indexing is little-endian: qubit 0 is the least-significant bit of @@ -2222,6 +2752,34 @@ fn matrix_unit_index(dim: usize, row: usize, col: usize) -> usize { row + col * dim } +fn vectorize_matrix(matrix: &DMatrix) -> DMatrix { + DMatrix::from_fn(matrix.nrows() * matrix.ncols(), 1, |idx, _| { + let row = idx % matrix.nrows(); + let col = idx / matrix.nrows(); + matrix[(row, col)] + }) +} + +fn complex_kronecker(left: &DMatrix, right: &DMatrix) -> DMatrix { + let rows = left.nrows() * right.nrows(); + let cols = left.ncols() * right.ncols(); + let mut out = DMatrix::zeros(rows, cols); + for left_row in 0..left.nrows() { + for left_col in 0..left.ncols() { + let scale = left[(left_row, left_col)]; + for right_row in 0..right.nrows() { + for right_col in 0..right.ncols() { + out[( + left_row * right.nrows() + right_row, + left_col * right.ncols() + right_col, + )] = scale * right[(right_row, right_col)]; + } + } + } + } + out +} + fn trace_complex(matrix: &DMatrix) -> Complex64 { let n = matrix.nrows().min(matrix.ncols()); (0..n).map(|idx| matrix[(idx, idx)]).sum() @@ -2967,6 +3525,77 @@ mod tests { assert_matrix_close(recovered.matrix(), ptm.matrix()); } + #[test] + fn superop_identity_round_trips_through_channel_representations() { + let kraus = KrausOps::from_unitary(&unitary::I(0), 1).unwrap(); + let superop = SuperOp::from_kraus(&kraus).unwrap(); + let identity = DMatrix::::identity(4, 4); + assert_complex_matrix_close(superop.matrix(), &identity); + + let choi = superop.to_choi().unwrap(); + let expected_choi = ChoiMatrix::from_kraus(&kraus).unwrap(); + assert_complex_matrix_close(choi.matrix(), expected_choi.matrix()); + + let ptm = superop.to_ptm().unwrap(); + assert_matrix_close(ptm.matrix(), Ptm::identity(1).unwrap().matrix()); + } + + #[test] + fn superop_compose_and_tensor_follow_matrix_semantics() { + let x = KrausOps::from_unitary(&unitary::X(0), 1) + .unwrap() + .to_superop() + .unwrap(); + let xx = x.compose(&x).unwrap(); + assert_complex_matrix_close(xx.matrix(), &DMatrix::::identity(4, 4)); + + let identity = KrausOps::from_unitary(&unitary::I(0), 1) + .unwrap() + .to_superop() + .unwrap(); + let tensor = identity.tensor(&identity).unwrap(); + assert_eq!(tensor.num_qubits(), 2); + assert_complex_matrix_close(tensor.matrix(), &DMatrix::::identity(16, 16)); + } + + #[test] + fn chi_matrix_is_diagonal_for_pauli_mixture() { + let expr = ChannelExpr::MixedUnitary(vec![(0.7, unitary::I(0)), (0.3, unitary::X(0))]); + let chi = ChiMatrix::from_channel_expr(&expr).unwrap(); + let identity = basis_index(1, &PauliBitmaskSmall::identity()).unwrap(); + let x = basis_index(1, &PauliBitmaskSmall::x(0)).unwrap(); + + assert_complex_close(chi.matrix()[(identity, identity)], Complex64::new(0.7, 0.0)); + assert_complex_close(chi.matrix()[(x, x)], Complex64::new(0.3, 0.0)); + for row in 0..chi.matrix().nrows() { + for col in 0..chi.matrix().ncols() { + if (row, col) != (identity, identity) && (row, col) != (x, x) { + assert!(chi.matrix()[(row, col)].norm() < 1e-10); + } + } + } + + let recovered = chi.to_ptm().unwrap(); + let expected = Ptm::from_channel_expr(&expr).unwrap(); + assert_matrix_close(recovered.matrix(), expected.matrix()); + } + + #[test] + fn stinespring_round_trips_trace_preserving_kraus_channels() { + let Op::Channel(expr) = op::AmplitudeDamping(0.25, 0) else { + panic!("expected channel"); + }; + let kraus = KrausOps::from_channel_expr(&expr).unwrap(); + let stinespring = kraus.to_stinespring().unwrap(); + assert_eq!(stinespring.num_qubits(), 1); + assert_eq!(stinespring.environment_dim(), kraus.operators().len()); + + let recovered = stinespring.to_kraus().unwrap(); + let expected_choi = kraus.to_choi().unwrap(); + let recovered_choi = recovered.to_choi().unwrap(); + assert_complex_matrix_close(recovered_choi.matrix(), expected_choi.matrix()); + } + #[test] fn invalid_choi_shape_fails_construction() { let err = ChoiMatrix::try_new(1, DMatrix::zeros(2, 2)).unwrap_err(); diff --git a/crates/pecos-quantum/src/lib.rs b/crates/pecos-quantum/src/lib.rs index dd18f52da..3ec7bb8a7 100644 --- a/crates/pecos-quantum/src/lib.rs +++ b/crates/pecos-quantum/src/lib.rs @@ -102,11 +102,12 @@ pub use pecos_num::dag::DagWouldCycleError; // Concrete channel representation types pub use channel::{ - ChannelError, ChoiMatrix, DiagonalPtm, KrausOps, PauliChannel, PauliSum, Ptm, PtmBasisOrder, - basis_bitmask, basis_digit_to_pauli, basis_element, basis_index, basis_label, bitmask_label, - matrix_unit_basis, partial_trace, pauli_basis_len, pauli_string_to_bitmask, - pauli_to_basis_digit, random_1q_clifford, random_2q_clifford, random_clifford, - random_density_matrix, random_density_matrix_with_rank, random_pauli, random_quantum_channel, + ChannelError, ChiMatrix, ChoiMatrix, DiagonalPtm, KrausOps, PauliChannel, PauliSum, Ptm, + PtmBasisOrder, Stinespring, SuperOp, basis_bitmask, basis_digit_to_pauli, basis_element, + basis_index, basis_label, bitmask_label, matrix_unit_basis, partial_trace, pauli_basis_len, + pauli_string_to_bitmask, pauli_to_basis_digit, random_1q_clifford, random_2q_clifford, + random_clifford, random_density_matrix, random_density_matrix_with_rank, random_pauli, + random_quantum_channel, }; pub use diamond_norm::{ DiamondNormError, hermitian_to_real_symmetric, hermitian_to_real_symmetric_with_tolerance, @@ -114,7 +115,7 @@ pub use diamond_norm::{ smat_real_symmetric, svec_real_symmetric, svec_real_symmetric_with_tolerance, }; pub use measures::{ - DensityMatrixPartialTrace, MeasureError, average_gate_fidelity, concurrence, + DensityMatrixPartialTrace, MeasureError, SchmidtTerm, average_gate_fidelity, concurrence, entanglement_of_formation, entropy, entropy_with_base, gate_error, hellinger_distance, hellinger_fidelity, logarithmic_negativity, mutual_information, negativity, partial_trace_qubits, partial_trace_subsystems, process_fidelity, purity, diff --git a/crates/pecos-quantum/src/measures.rs b/crates/pecos-quantum/src/measures.rs index d063e554b..f142dee98 100644 --- a/crates/pecos-quantum/src/measures.rs +++ b/crates/pecos-quantum/src/measures.rs @@ -25,6 +25,11 @@ use crate::channel::Ptm; const DEFAULT_TOLERANCE: f64 = 1e-12; +/// One term in a Schmidt decomposition. +/// +/// The tuple is `(coefficient, left_vector, right_vector)`. +pub type SchmidtTerm = (f64, Vec, Vec); + /// Error returned by quantum-information measure functions. #[derive(Debug, Clone, PartialEq)] pub enum MeasureError { @@ -573,7 +578,7 @@ pub fn schmidt_decomposition( state: &DVector, dims: &[usize], left_subsystems: &[usize], -) -> Result, Vec)>, MeasureError> { +) -> Result, MeasureError> { validate_state_vector(state)?; validate_state_subsystem_dimensions(state.len(), dims)?; let left = validated_sorted_subsystems(dims, left_subsystems)?; @@ -605,6 +610,7 @@ pub fn schmidt_decomposition( let right_vector = right_vectors_adjoint .row(idx) .iter() + .copied() .map(|value| value.conj()) .collect(); (coefficient, left_vector, right_vector) From df39e4fd416aae8bf23133c134bd6f42b04b318a Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 01:13:16 -0600 Subject: [PATCH 086/125] Expose quantum info additions to Python --- docs/user-guide/quantum-info.md | 45 ++- python/pecos-rslib/pecos_rslib.pyi | 65 ++++- .../src/pauli_sequence_bindings.rs | 9 + .../pecos-rslib/src/quantum_info_bindings.rs | 273 +++++++++++++++++- .../quantum-pecos/src/pecos/quantum_info.py | 20 ++ .../tests/pecos/test_quantum_info_bindings.py | 40 +++ 6 files changed, 445 insertions(+), 7 deletions(-) diff --git a/docs/user-guide/quantum-info.md b/docs/user-guide/quantum-info.md index ceef59e57..688770308 100644 --- a/docs/user-guide/quantum-info.md +++ b/docs/user-guide/quantum-info.md @@ -10,7 +10,7 @@ fault catalog. ## Channel Representations -PECOS currently provides four concrete channel representations: +PECOS currently provides seven concrete channel representations: | Type | Purpose | | ---- | ------- | @@ -18,6 +18,9 @@ PECOS currently provides four concrete channel representations: | `Ptm` | Dense Pauli transfer matrix. | | `KrausOps` | Kraus-operator representation. | | `ChoiMatrix` | Choi-matrix representation for channel validation and tomography. | +| `SuperOp` | Dense column-stacked superoperator. | +| `ChiMatrix` | Process matrix in the Pauli basis. | +| `Stinespring` | Stinespring isometry. | The representations use PECOS's little-endian qubit convention. Pauli-channel labels are displayed with the highest-numbered qubit first, so label `IX` on two @@ -87,12 +90,35 @@ trace_check = choi.partial_trace_output() For PECOS's Choi convention, a trace-preserving channel satisfies `partial_trace_output() == I`. +The dense channel forms convert through the same Rust-backed validation path: + +```python +from pecos.quantum_info import Ptm + +ptm = Ptm.identity(1) +superop = ptm.to_superop() +chi = ptm.to_chi() +stinespring = ptm.to_kraus().to_stinespring() + +assert superop.to_ptm().matrix() == ptm.matrix() +assert chi.to_ptm().matrix() == ptm.matrix() +assert stinespring.to_kraus().is_trace_preserving() +``` + ## State and Process Measures State measures accept Python lists of complex values: ```python -from pecos.quantum_info import purity, state_fidelity +from pecos.quantum_info import ( + entropy, + hellinger_distance, + negativity, + purity, + schmidt_decomposition, + shannon_entropy, + state_fidelity, +) zero = [1.0 + 0.0j, 0.0 + 0.0j] plus = [2.0**-0.5, 2.0**-0.5] @@ -102,6 +128,21 @@ assert abs(state_fidelity(zero, plus) - 0.5) < 1e-12 rho_zero = [[1.0 + 0.0j, 0.0 + 0.0j], [0.0 + 0.0j, 0.0 + 0.0j]] assert purity(rho_zero) == 1.0 +assert entropy(rho_zero) == 0.0 + +bell = [2.0**-0.5 + 0.0j, 0.0j, 0.0j, 2.0**-0.5 + 0.0j] +bell_rho = [ + [0.5 + 0.0j, 0.0j, 0.0j, 0.5 + 0.0j], + [0.0j, 0.0j, 0.0j, 0.0j], + [0.0j, 0.0j, 0.0j, 0.0j], + [0.5 + 0.0j, 0.0j, 0.0j, 0.5 + 0.0j], +] + +assert abs(negativity(bell_rho, [2, 2], 1) - 0.5) < 1e-12 +assert len(schmidt_decomposition(bell, [2, 2], [0])) == 2 + +assert shannon_entropy([0.5, 0.5], 2.0) == 1.0 +assert hellinger_distance([1.0, 0.0], [0.0, 1.0]) == 1.0 ``` Process measures operate on `Ptm` values: diff --git a/python/pecos-rslib/pecos_rslib.pyi b/python/pecos-rslib/pecos_rslib.pyi index a30a2722f..1e1f17f5e 100644 --- a/python/pecos-rslib/pecos_rslib.pyi +++ b/python/pecos-rslib/pecos_rslib.pyi @@ -1035,7 +1035,7 @@ class PauliStabilizerGroup: class PauliSequence: """Ordered sequence of Pauli operators with symplectic analysis.""" - ... + def group_commuting(self) -> list[PauliSequence]: ... class CliffordRep: """Clifford gate in the Heisenberg picture.""" @@ -1182,6 +1182,8 @@ class Ptm: def entry(self, output: int, input: int) -> float: ... def to_choi(self) -> ChoiMatrix: ... def to_kraus(self) -> KrausOps: ... + def to_superop(self) -> SuperOp: ... + def to_chi(self) -> ChiMatrix: ... class KrausOps: """Kraus-operator channel representation.""" @@ -1192,6 +1194,9 @@ class KrausOps: def is_trace_preserving(self) -> bool: ... def to_ptm(self) -> Ptm: ... def to_choi(self) -> ChoiMatrix: ... + def to_superop(self) -> SuperOp: ... + def to_chi(self) -> ChiMatrix: ... + def to_stinespring(self) -> Stinespring: ... class ChoiMatrix: """Choi-matrix channel representation.""" @@ -1208,10 +1213,55 @@ class ChoiMatrix: def is_unital(self) -> bool: ... def to_ptm(self) -> Ptm: ... def to_kraus(self) -> KrausOps: ... + def to_superop(self) -> SuperOp: ... + def to_chi(self) -> ChiMatrix: ... + +class SuperOp: + """Column-stacked superoperator channel representation.""" + + def __init__(self, num_qubits: int, matrix: ComplexMatrix) -> None: ... + def num_qubits(self) -> int: ... + def matrix(self) -> list[list[complex]]: ... + def to_choi(self) -> ChoiMatrix: ... + def to_ptm(self) -> Ptm: ... + def to_kraus(self) -> KrausOps: ... + def compose(self, other: SuperOp) -> SuperOp: ... + def tensor(self, other: SuperOp) -> SuperOp: ... + +class ChiMatrix: + """Pauli-basis process matrix.""" + + def __init__(self, num_qubits: int, matrix: ComplexMatrix) -> None: ... + def num_qubits(self) -> int: ... + def matrix(self) -> list[list[complex]]: ... + def to_choi(self) -> ChoiMatrix: ... + def to_ptm(self) -> Ptm: ... + +class Stinespring: + """Stinespring isometry channel representation.""" + + def __init__(self, num_qubits: int, isometry: ComplexMatrix) -> None: ... + def num_qubits(self) -> int: ... + def environment_dim(self) -> int: ... + def isometry(self) -> list[list[complex]]: ... + def to_kraus(self) -> KrausOps: ... + def to_choi(self) -> ChoiMatrix: ... + def to_superop(self) -> SuperOp: ... def state_fidelity(left: Sequence[complex], right: Sequence[complex]) -> float: ... def state_fidelity_with_density_matrix(rho: ComplexMatrix, psi: Sequence[complex]) -> float: ... def purity(rho: ComplexMatrix) -> float: ... +def entropy(rho: ComplexMatrix) -> float: ... +def shannon_entropy(probabilities: Sequence[float], base: float) -> float: ... +def negativity(rho: ComplexMatrix, dims: Sequence[int], subsystem: int) -> float: ... +def logarithmic_negativity(rho: ComplexMatrix, dims: Sequence[int], subsystem: int) -> float: ... +def schmidt_decomposition( + state: Sequence[complex], + dims: Sequence[int], + left_subsystems: Sequence[int], +) -> list[tuple[float, list[complex], list[complex]]]: ... +def hellinger_distance(left: Sequence[float], right: Sequence[float]) -> float: ... +def hellinger_fidelity(left: Sequence[float], right: Sequence[float]) -> float: ... def process_fidelity(left: Ptm, right: Ptm) -> float: ... def average_gate_fidelity(left: Ptm, right: Ptm) -> float: ... def gate_error(left: Ptm, right: Ptm) -> float: ... @@ -1322,9 +1372,22 @@ class quantum_info: Ptm: type[Ptm] KrausOps: type[KrausOps] ChoiMatrix: type[ChoiMatrix] + SuperOp: type[SuperOp] + ChiMatrix: type[ChiMatrix] + Stinespring: type[Stinespring] state_fidelity: Callable[[Sequence[complex], Sequence[complex]], float] state_fidelity_with_density_matrix: Callable[[ComplexMatrix, Sequence[complex]], float] purity: Callable[[ComplexMatrix], float] + entropy: Callable[[ComplexMatrix], float] + shannon_entropy: Callable[[Sequence[float], float], float] + negativity: Callable[[ComplexMatrix, Sequence[int], int], float] + logarithmic_negativity: Callable[[ComplexMatrix, Sequence[int], int], float] + schmidt_decomposition: Callable[ + [Sequence[complex], Sequence[int], Sequence[int]], + list[tuple[float, list[complex], list[complex]]], + ] + hellinger_distance: Callable[[Sequence[float], Sequence[float]], float] + hellinger_fidelity: Callable[[Sequence[float], Sequence[float]], float] process_fidelity: Callable[[Ptm, Ptm], float] average_gate_fidelity: Callable[[Ptm, Ptm], float] gate_error: Callable[[Ptm, Ptm], float] diff --git a/python/pecos-rslib/src/pauli_sequence_bindings.rs b/python/pecos-rslib/src/pauli_sequence_bindings.rs index e08cfe5ff..f6cf9cf3d 100644 --- a/python/pecos-rslib/src/pauli_sequence_bindings.rs +++ b/python/pecos-rslib/src/pauli_sequence_bindings.rs @@ -131,6 +131,15 @@ impl PyPauliSequence { self.inner.commutation_matrix().rows() } + /// Greedily partition Pauli strings into mutually commuting groups. + fn group_commuting(&self) -> Vec { + self.inner + .group_commuting() + .into_iter() + .map(|inner| Self { inner }) + .collect() + } + /// Row-reduced form: independent Pauli strings in echelon form. /// /// Returns a new PauliSequence with redundant elements removed and diff --git a/python/pecos-rslib/src/quantum_info_bindings.rs b/python/pecos-rslib/src/quantum_info_bindings.rs index 3b912d4f6..a4c34dc79 100644 --- a/python/pecos-rslib/src/quantum_info_bindings.rs +++ b/python/pecos-rslib/src/quantum_info_bindings.rs @@ -18,10 +18,14 @@ use nalgebra::{DMatrix, DVector}; use num_complex::Complex64; use pecos_core::PauliBitmaskSmall; use pecos_quantum::{ - ChoiMatrix as RustChoiMatrix, KrausOps as RustKrausOps, PauliChannel as RustPauliChannel, - Ptm as RustPtm, average_gate_fidelity as rust_average_gate_fidelity, - gate_error as rust_gate_error, pauli_basis_len, process_fidelity as rust_process_fidelity, - purity as rust_purity, random_density_matrix as rust_random_density_matrix, + ChiMatrix as RustChiMatrix, ChoiMatrix as RustChoiMatrix, KrausOps as RustKrausOps, + PauliChannel as RustPauliChannel, Ptm as RustPtm, Stinespring as RustStinespring, + SuperOp as RustSuperOp, average_gate_fidelity as rust_average_gate_fidelity, + entropy as rust_entropy, gate_error as rust_gate_error, + hellinger_distance as rust_hellinger_distance, hellinger_fidelity as rust_hellinger_fidelity, + logarithmic_negativity as rust_logarithmic_negativity, negativity as rust_negativity, + pauli_basis_len, process_fidelity as rust_process_fidelity, purity as rust_purity, + random_density_matrix as rust_random_density_matrix, random_quantum_channel as rust_random_quantum_channel, state_fidelity as rust_state_fidelity, state_fidelity_with_density_matrix as rust_state_fidelity_with_density_matrix, }; @@ -29,6 +33,8 @@ use pecos_random::PecosRng; use pyo3::prelude::*; use pyo3::types::{PyDict, PyModule}; +type PySchmidtTerm = (f64, Vec, Vec); + fn py_value_err(err: impl std::fmt::Display) -> PyErr { pyo3::exceptions::PyValueError::new_err(err.to_string()) } @@ -220,6 +226,18 @@ impl PyPtm { }) } + fn to_superop(&self) -> PyResult { + Ok(PySuperOp { + inner: self.inner.to_superop().map_err(py_value_err)?, + }) + } + + fn to_chi(&self) -> PyResult { + Ok(PyChiMatrix { + inner: self.inner.to_chi().map_err(py_value_err)?, + }) + } + fn __repr__(&self) -> String { format!("Ptm(num_qubits={})", self.inner.num_qubits()) } @@ -271,6 +289,24 @@ impl PyKrausOps { }) } + fn to_superop(&self) -> PyResult { + Ok(PySuperOp { + inner: self.inner.to_superop().map_err(py_value_err)?, + }) + } + + fn to_chi(&self) -> PyResult { + Ok(PyChiMatrix { + inner: self.inner.to_chi().map_err(py_value_err)?, + }) + } + + fn to_stinespring(&self) -> PyResult { + Ok(PyStinespring { + inner: self.inner.to_stinespring().map_err(py_value_err)?, + }) + } + fn __repr__(&self) -> String { format!("KrausOps(num_qubits={})", self.inner.num_qubits()) } @@ -348,11 +384,175 @@ impl PyChoiMatrix { }) } + fn to_superop(&self) -> PyResult { + Ok(PySuperOp { + inner: self.inner.to_superop().map_err(py_value_err)?, + }) + } + + fn to_chi(&self) -> PyResult { + Ok(PyChiMatrix { + inner: self.inner.to_chi().map_err(py_value_err)?, + }) + } + fn __repr__(&self) -> String { format!("ChoiMatrix(num_qubits={})", self.inner.num_qubits()) } } +#[pyclass(name = "SuperOp", module = "pecos_rslib.quantum_info")] +pub struct PySuperOp { + inner: RustSuperOp, +} + +#[pymethods] +impl PySuperOp { + #[new] + fn new(num_qubits: usize, matrix: Vec>) -> PyResult { + Ok(Self { + inner: RustSuperOp::try_new(num_qubits, complex_matrix_from_rows(matrix)?) + .map_err(py_value_err)?, + }) + } + + fn num_qubits(&self) -> usize { + self.inner.num_qubits() + } + + fn matrix(&self) -> Vec> { + complex_matrix_to_rows(self.inner.matrix()) + } + + fn to_choi(&self) -> PyResult { + Ok(PyChoiMatrix { + inner: self.inner.to_choi().map_err(py_value_err)?, + }) + } + + fn to_ptm(&self) -> PyResult { + Ok(PyPtm { + inner: self.inner.to_ptm().map_err(py_value_err)?, + }) + } + + fn to_kraus(&self) -> PyResult { + Ok(PyKrausOps { + inner: self.inner.to_kraus().map_err(py_value_err)?, + }) + } + + fn compose(&self, other: &PySuperOp) -> PyResult { + Ok(PySuperOp { + inner: self.inner.compose(&other.inner).map_err(py_value_err)?, + }) + } + + fn tensor(&self, other: &PySuperOp) -> PyResult { + Ok(PySuperOp { + inner: self.inner.tensor(&other.inner).map_err(py_value_err)?, + }) + } + + fn __repr__(&self) -> String { + format!("SuperOp(num_qubits={})", self.inner.num_qubits()) + } +} + +#[pyclass(name = "ChiMatrix", module = "pecos_rslib.quantum_info")] +pub struct PyChiMatrix { + inner: RustChiMatrix, +} + +#[pymethods] +impl PyChiMatrix { + #[new] + fn new(num_qubits: usize, matrix: Vec>) -> PyResult { + Ok(Self { + inner: RustChiMatrix::try_new(num_qubits, complex_matrix_from_rows(matrix)?) + .map_err(py_value_err)?, + }) + } + + fn num_qubits(&self) -> usize { + self.inner.num_qubits() + } + + fn matrix(&self) -> Vec> { + complex_matrix_to_rows(self.inner.matrix()) + } + + fn to_choi(&self) -> PyResult { + Ok(PyChoiMatrix { + inner: self.inner.to_choi().map_err(py_value_err)?, + }) + } + + fn to_ptm(&self) -> PyResult { + Ok(PyPtm { + inner: self.inner.to_ptm().map_err(py_value_err)?, + }) + } + + fn __repr__(&self) -> String { + format!("ChiMatrix(num_qubits={})", self.inner.num_qubits()) + } +} + +#[pyclass(name = "Stinespring", module = "pecos_rslib.quantum_info")] +pub struct PyStinespring { + inner: RustStinespring, +} + +#[pymethods] +impl PyStinespring { + #[new] + fn new(num_qubits: usize, isometry: Vec>) -> PyResult { + Ok(Self { + inner: RustStinespring::try_new(num_qubits, complex_matrix_from_rows(isometry)?) + .map_err(py_value_err)?, + }) + } + + fn num_qubits(&self) -> usize { + self.inner.num_qubits() + } + + fn environment_dim(&self) -> usize { + self.inner.environment_dim() + } + + fn isometry(&self) -> Vec> { + complex_matrix_to_rows(self.inner.isometry()) + } + + fn to_kraus(&self) -> PyResult { + Ok(PyKrausOps { + inner: self.inner.to_kraus().map_err(py_value_err)?, + }) + } + + fn to_choi(&self) -> PyResult { + Ok(PyChoiMatrix { + inner: self.inner.to_choi().map_err(py_value_err)?, + }) + } + + fn to_superop(&self) -> PyResult { + Ok(PySuperOp { + inner: self.inner.to_superop().map_err(py_value_err)?, + }) + } + + fn __repr__(&self) -> String { + format!( + "Stinespring(num_qubits={}, environment_dim={})", + self.inner.num_qubits(), + self.inner.environment_dim() + ) + } +} + #[pyfunction] fn state_fidelity(left: Vec, right: Vec) -> PyResult { rust_state_fidelity(&DVector::from_vec(left), &DVector::from_vec(right)).map_err(py_value_err) @@ -375,6 +575,51 @@ fn purity(rho: Vec>) -> PyResult { rust_purity(&complex_matrix_from_rows(rho)?).map_err(py_value_err) } +#[pyfunction] +fn entropy(rho: Vec>) -> PyResult { + rust_entropy(&complex_matrix_from_rows(rho)?).map_err(py_value_err) +} + +#[pyfunction] +fn shannon_entropy(probabilities: Vec, base: f64) -> PyResult { + pecos_quantum::shannon_entropy(&probabilities, base).map_err(py_value_err) +} + +#[pyfunction] +fn negativity(rho: Vec>, dims: Vec, subsystem: usize) -> PyResult { + rust_negativity(&complex_matrix_from_rows(rho)?, &dims, subsystem).map_err(py_value_err) +} + +#[pyfunction] +fn logarithmic_negativity( + rho: Vec>, + dims: Vec, + subsystem: usize, +) -> PyResult { + rust_logarithmic_negativity(&complex_matrix_from_rows(rho)?, &dims, subsystem) + .map_err(py_value_err) +} + +#[pyfunction] +fn schmidt_decomposition( + state: Vec, + dims: Vec, + left_subsystems: Vec, +) -> PyResult> { + pecos_quantum::schmidt_decomposition(&DVector::from_vec(state), &dims, &left_subsystems) + .map_err(py_value_err) +} + +#[pyfunction] +fn hellinger_distance(left: Vec, right: Vec) -> PyResult { + rust_hellinger_distance(&left, &right).map_err(py_value_err) +} + +#[pyfunction] +fn hellinger_fidelity(left: Vec, right: Vec) -> PyResult { + rust_hellinger_fidelity(&left, &right).map_err(py_value_err) +} + #[pyfunction] fn process_fidelity(left: &PyPtm, right: &PyPtm) -> PyResult { rust_process_fidelity(&left.inner, &right.inner).map_err(py_value_err) @@ -422,6 +667,9 @@ pub fn register_quantum_info_module(parent: &Bound<'_, PyModule>) -> PyResult<() parent.add_class::()?; parent.add_class::()?; parent.add_class::()?; + parent.add_class::()?; + parent.add_class::()?; + parent.add_class::()?; parent.add_function(wrap_pyfunction!(state_fidelity, parent)?)?; parent.add_function(wrap_pyfunction!( @@ -429,6 +677,13 @@ pub fn register_quantum_info_module(parent: &Bound<'_, PyModule>) -> PyResult<() parent )?)?; parent.add_function(wrap_pyfunction!(purity, parent)?)?; + parent.add_function(wrap_pyfunction!(entropy, parent)?)?; + parent.add_function(wrap_pyfunction!(shannon_entropy, parent)?)?; + parent.add_function(wrap_pyfunction!(negativity, parent)?)?; + parent.add_function(wrap_pyfunction!(logarithmic_negativity, parent)?)?; + parent.add_function(wrap_pyfunction!(schmidt_decomposition, parent)?)?; + parent.add_function(wrap_pyfunction!(hellinger_distance, parent)?)?; + parent.add_function(wrap_pyfunction!(hellinger_fidelity, parent)?)?; parent.add_function(wrap_pyfunction!(process_fidelity, parent)?)?; parent.add_function(wrap_pyfunction!(average_gate_fidelity, parent)?)?; parent.add_function(wrap_pyfunction!(gate_error, parent)?)?; @@ -444,9 +699,19 @@ pub fn register_quantum_info_module(parent: &Bound<'_, PyModule>) -> PyResult<() "Ptm", "KrausOps", "ChoiMatrix", + "SuperOp", + "ChiMatrix", + "Stinespring", "state_fidelity", "state_fidelity_with_density_matrix", "purity", + "entropy", + "shannon_entropy", + "negativity", + "logarithmic_negativity", + "schmidt_decomposition", + "hellinger_distance", + "hellinger_fidelity", "process_fidelity", "average_gate_fidelity", "gate_error", diff --git a/python/quantum-pecos/src/pecos/quantum_info.py b/python/quantum-pecos/src/pecos/quantum_info.py index 558eb6d31..dbdb30f05 100644 --- a/python/quantum-pecos/src/pecos/quantum_info.py +++ b/python/quantum-pecos/src/pecos/quantum_info.py @@ -8,35 +8,55 @@ from __future__ import annotations from pecos_rslib.quantum_info import ( + ChiMatrix, ChoiMatrix, KrausOps, PauliChannel, Ptm, + Stinespring, + SuperOp, average_gate_fidelity, + entropy, gate_error, + hellinger_distance, + hellinger_fidelity, + logarithmic_negativity, + negativity, pauli_channel_diamond_distance, pauli_channel_diamond_norm, process_fidelity, purity, random_density_matrix, random_quantum_channel, + schmidt_decomposition, + shannon_entropy, state_fidelity, state_fidelity_with_density_matrix, ) __all__ = [ + "ChiMatrix", "ChoiMatrix", "KrausOps", "PauliChannel", "Ptm", + "Stinespring", + "SuperOp", "average_gate_fidelity", + "entropy", "gate_error", + "hellinger_distance", + "hellinger_fidelity", + "logarithmic_negativity", + "negativity", "pauli_channel_diamond_distance", "pauli_channel_diamond_norm", "process_fidelity", "purity", "random_density_matrix", "random_quantum_channel", + "schmidt_decomposition", + "shannon_entropy", "state_fidelity", "state_fidelity_with_density_matrix", ] diff --git a/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py b/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py index 3519d455e..d50c27116 100644 --- a/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py +++ b/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py @@ -1,17 +1,27 @@ from __future__ import annotations from pecos.quantum_info import ( + ChiMatrix, ChoiMatrix, PauliChannel, Ptm, + Stinespring, + SuperOp, average_gate_fidelity, + entropy, gate_error, + hellinger_distance, + hellinger_fidelity, + logarithmic_negativity, + negativity, pauli_channel_diamond_distance, pauli_channel_diamond_norm, process_fidelity, purity, random_density_matrix, random_quantum_channel, + schmidt_decomposition, + shannon_entropy, state_fidelity, state_fidelity_with_density_matrix, ) @@ -66,16 +76,46 @@ def test_choi_and_kraus_wrappers_round_trip_identity_channel() -> None: assert_close(average_gate_fidelity(kraus.to_ptm(), identity), 1.0) assert_close(gate_error(kraus.to_ptm(), identity), 0.0) + superop = kraus.to_superop() + assert isinstance(superop, SuperOp) + assert_close(process_fidelity(superop.to_ptm(), identity), 1.0) + + chi = kraus.to_chi() + assert isinstance(chi, ChiMatrix) + assert_close(process_fidelity(chi.to_ptm(), identity), 1.0) + + stinespring = kraus.to_stinespring() + assert isinstance(stinespring, Stinespring) + assert stinespring.environment_dim() == 1 + assert_close(process_fidelity(stinespring.to_kraus().to_ptm(), identity), 1.0) + def test_state_measure_wrappers() -> None: zero = [1.0 + 0.0j, 0.0 + 0.0j] plus = [2.0**-0.5 + 0.0j, 2.0**-0.5 + 0.0j] zero_density = [[1.0 + 0.0j, 0.0 + 0.0j], [0.0 + 0.0j, 0.0 + 0.0j]] + bell = [2.0**-0.5 + 0.0j, 0.0 + 0.0j, 0.0 + 0.0j, 2.0**-0.5 + 0.0j] + bell_density = [ + [0.5 + 0.0j, 0.0 + 0.0j, 0.0 + 0.0j, 0.5 + 0.0j], + [0.0 + 0.0j, 0.0 + 0.0j, 0.0 + 0.0j, 0.0 + 0.0j], + [0.0 + 0.0j, 0.0 + 0.0j, 0.0 + 0.0j, 0.0 + 0.0j], + [0.5 + 0.0j, 0.0 + 0.0j, 0.0 + 0.0j, 0.5 + 0.0j], + ] assert_close(state_fidelity(zero, zero), 1.0) assert_close(state_fidelity(zero, plus), 0.5) assert_close(state_fidelity_with_density_matrix(zero_density, zero), 1.0) assert_close(purity(zero_density), 1.0) + assert_close(entropy(zero_density), 0.0) + assert_close(shannon_entropy([0.5, 0.5], 2.0), 1.0) + assert_close(negativity(bell_density, [2, 2], 1), 0.5) + assert_close(logarithmic_negativity(bell_density, [2, 2], 1), 1.0) + assert_close(hellinger_distance([1.0, 0.0], [0.0, 1.0]), 1.0) + assert_close(hellinger_fidelity([0.25, 0.75], [0.25, 0.75]), 1.0) + schmidt = schmidt_decomposition(bell, [2, 2], [0]) + assert len(schmidt) == 2 + assert_close(schmidt[0][0], 2.0**-0.5) + assert_close(schmidt[1][0], 2.0**-0.5) def test_random_generators_are_seed_reproducible_and_valid() -> None: From b19c9f07d20d2fd964e536db49b97c24919df8c2 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 12:02:11 -0600 Subject: [PATCH 087/125] Add first-class channel noise compilation --- Cargo.lock | 1 + crates/pecos-core/src/gate_type.rs | 23 +- crates/pecos-core/src/gates.rs | 102 +++++++++ .../pecos-engines/src/byte_message/builder.rs | 20 ++ .../pecos-engines/src/byte_message/message.rs | 44 +++- .../src/noise/biased_depolarizing.rs | 13 ++ .../pecos-engines/src/noise/depolarizing.rs | 22 +- crates/pecos-engines/src/noise/general.rs | 15 ++ crates/pecos-engines/src/quantum.rs | 36 ++- crates/pecos-qasm/src/engine.rs | 2 +- crates/pecos-quantum/src/channel.rs | 40 ++++ crates/pecos-quantum/src/circuit_display.rs | 2 + crates/pecos-quantum/src/tick_circuit.rs | 211 +++++++++++++++++- crates/pecos-quantum/src/unitary_matrix.rs | 1 + crates/pecos-simulators/Cargo.toml | 1 + crates/pecos-simulators/src/density_matrix.rs | 91 +++++++- crates/pecos-simulators/src/state_access.rs | 2 +- exp/pecos-eeg/examples/profile_heisenberg.rs | 1 + exp/pecos-eeg/src/circuit.rs | 1 + exp/pecos-eeg/src/dem_mapping.rs | 3 + exp/pecos-eeg/src/expand.rs | 1 + exp/pecos-eeg/src/heisenberg.rs | 1 + exp/pecos-eeg/src/noise_compression.rs | 1 + exp/pecos-eeg/src/stabilizer.rs | 1 + exp/pecos-eeg/tests/beta_investigation.rs | 1 + exp/pecos-eeg/tests/generator_trace.rs | 1 + exp/pecos-eeg/tests/stabilizer_audit.rs | 1 + exp/pecos-eeg/tests/statevec_comparison.rs | 1 + exp/pecos-experimental/src/hugr_executor.rs | 1 + exp/pecos-neo/src/adapter.rs | 60 +++-- exp/pecos-neo/src/circuit.rs | 14 +- python/pecos-rslib-exp/src/eeg_bindings.rs | 4 + .../pecos-rslib-exp/src/sim_neo_bindings.rs | 2 + 33 files changed, 671 insertions(+), 49 deletions(-) diff --git a/Cargo.lock b/Cargo.lock index 9540dda0e..87e768442 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -4502,6 +4502,7 @@ dependencies = [ name = "pecos-simulators" version = "0.2.0-dev.0" dependencies = [ + "nalgebra", "num-complex 0.4.6", "paste", "pecos-core", diff --git a/crates/pecos-core/src/gate_type.rs b/crates/pecos-core/src/gate_type.rs index 65bdd992b..d191e149c 100644 --- a/crates/pecos-core/src/gate_type.rs +++ b/crates/pecos-core/src/gate_type.rs @@ -120,6 +120,12 @@ pub enum GateType { PauliOperatorMeta = 210, MeasCrosstalkGlobalPayload = 218, MeasCrosstalkLocalPayload = 219, + /// Typed channel operation embedded in an annotated/noisy circuit. + /// + /// The concrete channel payload is stored on [`crate::Gate`], not in the + /// numeric gate type. Ideal circuits should not contain this gate type; it + /// represents compiled noise annotations or explicit channel placement. + Channel = 220, /// Custom/unrecognized gate type, with actual name stored in metadata Custom = 255, } @@ -175,6 +181,7 @@ impl From for GateType { 218 => GateType::MeasCrosstalkGlobalPayload, 219 => GateType::MeasCrosstalkLocalPayload, 210 => GateType::PauliOperatorMeta, + 220 => GateType::Channel, 255 => GateType::Custom, _ => panic!("Invalid gate type ID: {value}"), } @@ -232,6 +239,7 @@ impl GateType { | GateType::MeasureFree | GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload + | GateType::Channel | GateType::PZ | GateType::QAlloc | GateType::QFree @@ -299,9 +307,11 @@ impl GateType { | GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload | GateType::Custom - // PauliOperatorMeta is variable-arity but returns 1 here because - // gate validation checks `is_multiple_of(quantum_arity())` and any - // count is a multiple of 1. The actual qubit count is in the gate. + // PauliOperatorMeta and Channel are variable-arity but return 1 + // here because gate validation checks + // `is_multiple_of(quantum_arity())` and any count is a multiple + // of 1. The actual qubit count is in the gate. + | GateType::Channel | GateType::PauliOperatorMeta => 1, // Two-qubit gates @@ -429,6 +439,7 @@ impl fmt::Display for GateType { GateType::Idle => write!(f, "Idle"), GateType::MeasCrosstalkGlobalPayload => write!(f, "MeasCrosstalkGlobalPayload"), GateType::MeasCrosstalkLocalPayload => write!(f, "MeasCrosstalkLocalPayload"), + GateType::Channel => write!(f, "Channel"), GateType::Custom => write!(f, "Custom"), GateType::PauliOperatorMeta => write!(f, "PauliOperator"), } @@ -492,6 +503,7 @@ impl std::str::FromStr for GateType { "QALLOC" => Ok(GateType::QAlloc), "QFREE" => Ok(GateType::QFree), "IDLE" => Ok(GateType::Idle), + "CHANNEL" => Ok(GateType::Channel), _ => Err(format!("Unknown gate type: {s}")), } } @@ -527,6 +539,7 @@ mod tests { assert_eq!(GateType::Idle as u8, 200); assert_eq!(GateType::MeasCrosstalkGlobalPayload as u8, 218); assert_eq!(GateType::MeasCrosstalkLocalPayload as u8, 219); + assert_eq!(GateType::Channel as u8, 220); assert_eq!(GateType::Custom as u8, 255); assert_eq!(GateType::from(0u8), GateType::I); @@ -553,6 +566,7 @@ mod tests { assert_eq!(GateType::from(200u8), GateType::Idle); assert_eq!(GateType::from(218u8), GateType::MeasCrosstalkGlobalPayload); assert_eq!(GateType::from(219u8), GateType::MeasCrosstalkLocalPayload); + assert_eq!(GateType::from(220u8), GateType::Channel); assert_eq!(GateType::from(255u8), GateType::Custom); } @@ -570,6 +584,7 @@ mod tests { assert_eq!(GateType::from_str("SXXdg").unwrap(), GateType::SXXdg); assert_eq!(GateType::from_str("SYY").unwrap(), GateType::SYY); assert_eq!(GateType::from_str("SYYdg").unwrap(), GateType::SYYdg); + assert_eq!(GateType::from_str("Channel").unwrap(), GateType::Channel); assert_eq!(GateType::from_str("SWAP").unwrap(), GateType::SWAP); assert_eq!(GateType::from_str("CCX").unwrap(), GateType::CCX); @@ -616,6 +631,7 @@ mod tests { assert_eq!(GateType::MeasureFree.classical_arity(), 0); assert_eq!(GateType::MeasCrosstalkGlobalPayload.classical_arity(), 0); assert_eq!(GateType::MeasCrosstalkLocalPayload.classical_arity(), 0); + assert_eq!(GateType::Channel.classical_arity(), 0); assert_eq!(GateType::PZ.classical_arity(), 0); assert_eq!(GateType::QAlloc.classical_arity(), 0); assert_eq!(GateType::QFree.classical_arity(), 0); @@ -652,6 +668,7 @@ mod tests { assert_eq!(GateType::Idle.quantum_arity(), 1); assert_eq!(GateType::MeasCrosstalkGlobalPayload.quantum_arity(), 1); assert_eq!(GateType::MeasCrosstalkLocalPayload.quantum_arity(), 1); + assert_eq!(GateType::Channel.quantum_arity(), 1); // Two-qubit gates assert_eq!(GateType::CX.quantum_arity(), 2); diff --git a/crates/pecos-core/src/gates.rs b/crates/pecos-core/src/gates.rs index 10cf991ca..0d329f2b9 100644 --- a/crates/pecos-core/src/gates.rs +++ b/crates/pecos-core/src/gates.rs @@ -4,6 +4,7 @@ //! gate operation with its type, qubits, and parameters. use crate::Angle64; +use crate::ChannelExpr; use crate::MeasId; use crate::QubitId; use crate::gate_type::GateType; @@ -56,6 +57,11 @@ pub struct Gate { /// transformations. Empty for non-measurement gates. /// Follows the MLIR SSA pattern: defined once, referenced everywhere. pub meas_ids: GateMeasIds, + /// Typed channel payload for `GateType::Channel`. + /// + /// This is `None` for ideal circuit gates. It is populated only for + /// annotated/noisy circuits that explicitly carry channel operations. + pub channel: Option, } /// Legacy quantum gate representation for `ByteMessageBuilder` compatibility @@ -79,6 +85,7 @@ impl Gate { params: params.into(), qubits: qubits.into(), meas_ids: GateMeasIds::new(), + channel: None, } } @@ -128,6 +135,36 @@ impl Gate { Self::simple(GateType::Custom, qubits) } + /// Create a typed channel operation for an annotated/noisy circuit. + #[must_use] + pub fn channel(channel: ChannelExpr) -> Self { + let qubits = channel + .qubits() + .into_iter() + .map(QubitId) + .collect::(); + Self { + gate_type: GateType::Channel, + angles: GateAngles::new(), + params: GateParams::new(), + qubits, + meas_ids: GateMeasIds::new(), + channel: Some(channel), + } + } + + /// Returns the typed channel payload when this is a channel operation. + #[must_use] + pub fn channel_expr(&self) -> Option<&ChannelExpr> { + self.channel.as_ref() + } + + /// Returns true when this gate carries a channel payload. + #[must_use] + pub fn is_channel(&self) -> bool { + self.gate_type == GateType::Channel + } + /// Create Identity gate on multiple qubits #[must_use] pub fn i(qubits: &[impl Into + Copy]) -> Self { @@ -929,6 +966,9 @@ impl Gate { #[inline] #[must_use] pub fn classical_arity(&self) -> usize { + if self.is_channel() { + return 0; + } self.gate_type.classical_arity() } @@ -940,6 +980,9 @@ impl Gate { #[inline] #[must_use] pub fn quantum_arity(&self) -> usize { + if self.is_channel() { + return self.qubits.len().max(1); + } self.gate_type.quantum_arity() } @@ -947,6 +990,9 @@ impl Gate { #[inline] #[must_use] pub fn is_parameterized(&self) -> bool { + if self.is_channel() { + return false; + } self.gate_type.is_parameterized() } @@ -954,6 +1000,9 @@ impl Gate { #[inline] #[must_use] pub fn is_single_qubit(&self) -> bool { + if self.is_channel() { + return self.qubits.len() == 1; + } self.gate_type.is_single_qubit() } @@ -961,6 +1010,9 @@ impl Gate { #[inline] #[must_use] pub fn is_two_qubit(&self) -> bool { + if self.is_channel() { + return self.qubits.len() == 2; + } self.gate_type.is_two_qubit() } @@ -968,6 +1020,9 @@ impl Gate { #[inline] #[must_use] pub fn angle_arity(&self) -> usize { + if self.is_channel() { + return 0; + } self.gate_type.angle_arity() } @@ -983,6 +1038,32 @@ impl Gate { /// - The number of angles doesn't match the gate's angle arity /// - The number of qubits is not a multiple of the gate's quantum arity pub fn validate(&self) -> Result<(), String> { + if self.is_channel() { + let Some(channel) = &self.channel else { + return Err("GateType::Channel requires a channel payload".to_string()); + }; + if !self.angles.is_empty() || !self.params.is_empty() || !self.meas_ids.is_empty() { + return Err( + "Channel gates cannot carry angle, parameter, or measurement-id payloads" + .to_string(), + ); + } + let expected = channel + .qubits() + .into_iter() + .map(QubitId) + .collect::(); + if self.qubits != expected { + return Err(format!( + "Channel gate qubits {:?} do not match channel payload qubits {:?}", + self.qubits, expected + )); + } + return Ok(()); + } + if self.channel.is_some() { + return Err("Only GateType::Channel can carry a channel payload".to_string()); + } // Check angle parameters if self.angles.len() != self.angle_arity() { return Err(format!( @@ -1053,6 +1134,27 @@ mod tests { assert!(measure_gate.angles.is_empty()); } + #[test] + fn test_channel_gate_creation_and_validation() { + use crate::channel::{Dephasing, Depolarizing}; + + let gate = Gate::channel(Depolarizing(0.25, 0)); + assert_eq!(gate.gate_type, GateType::Channel); + assert_eq!(gate.qubits.as_slice(), &[QubitId::from(0)]); + assert!(gate.channel_expr().is_some()); + assert!(gate.validate().is_ok()); + + let two_qubit_channel = Depolarizing(0.1, 0) & Dephasing(0.2, 1); + let two_qubit_gate = Gate::channel(two_qubit_channel); + assert_eq!( + two_qubit_gate.qubits.as_slice(), + &[QubitId::from(0), QubitId::from(1)] + ); + assert_eq!(two_qubit_gate.quantum_arity(), 2); + assert!(two_qubit_gate.is_two_qubit()); + assert!(two_qubit_gate.validate().is_ok()); + } + #[test] fn test_two_qubit_gate_vec_variants() { // Test CX with _vec variant - much more convenient when you have a flat list diff --git a/crates/pecos-engines/src/byte_message/builder.rs b/crates/pecos-engines/src/byte_message/builder.rs index d641511f1..49ba0c43f 100644 --- a/crates/pecos-engines/src/byte_message/builder.rs +++ b/crates/pecos-engines/src/byte_message/builder.rs @@ -155,6 +155,10 @@ impl ByteMessageBuilder { where I: IntoIterator, { + assert!( + gate_type != GateType::Channel, + "Channel gates carry typed payloads and cannot be encoded in ByteMessage gate commands" + ); let payload_size = size_of::() + num_qubits * size_of::() + (angles.len() + params.len()) * size_of::(); @@ -326,6 +330,10 @@ impl ByteMessageBuilder { /// This function will panic if the number of qubits in the gate exceeds 255, /// as the protocol uses a u8 to represent the qubit count. pub fn add_gate_command(&mut self, gate: &Gate) -> &mut Self { + assert!( + !gate.is_channel(), + "Channel gates carry typed payloads and cannot be encoded in ByteMessage gate commands" + ); self.add_gate_parts_from_usizes( gate.gate_type, gate.qubits.len(), @@ -969,6 +977,18 @@ mod tests { assert!(!message.is_empty().unwrap()); } + #[test] + #[should_panic( + expected = "Channel gates carry typed payloads and cannot be encoded in ByteMessage gate commands" + )] + fn test_add_gate_command_rejects_channel_gate() { + let mut builder = ByteMessageBuilder::new(); + let _ = builder.for_quantum_operations(); + + let gate = Gate::channel(pecos_core::channel::Depolarizing(0.01, 0)); + builder.add_gate_command(&gate); + } + #[test] fn test_builder_basic() { // Create a builder diff --git a/crates/pecos-engines/src/byte_message/message.rs b/crates/pecos-engines/src/byte_message/message.rs index 35a9c7163..d8f2a308a 100644 --- a/crates/pecos-engines/src/byte_message/message.rs +++ b/crates/pecos-engines/src/byte_message/message.rs @@ -288,15 +288,7 @@ impl ByteMessage { } } - match Self::parse_gate_command(payload) { - Ok(cmd) => Some(cmd), - Err(e) => { - if trace_enabled { - trace!("Error parsing gate: {e}"); - } - None - } - } + Some(Self::parse_gate_command(payload)?) } else { None }; @@ -722,6 +714,12 @@ impl ByteMessage { let num_qubits = header.num_qubits as usize; let has_params = header.has_params != 0; let gate_type = GateType::from(header.gate_type); + if gate_type == GateType::Channel { + return Err(PecosError::Input( + "Channel gates carry typed payloads and cannot be encoded in ByteMessage gate commands" + .to_string(), + )); + } if trace_enabled { trace!( @@ -801,6 +799,34 @@ mod tests { ); } + #[test] + fn test_raw_channel_gate_message_is_rejected() { + use crate::byte_message::protocol::{GateHeader, MessageFlags, MessageType}; + + let header = GateHeader { + gate_type: GateType::Channel as u8, + num_qubits: 1, + has_params: 0, + reserved: 0, + }; + let mut payload = Vec::new(); + payload.extend_from_slice(bytemuck::bytes_of(&header)); + payload.extend_from_slice(&0u32.to_le_bytes()); + + let mut builder = ByteMessage::quantum_operations_builder(); + builder.add_message(MessageType::Gate, &payload, MessageFlags::NONE); + let message = builder.build(); + + let err = message + .quantum_ops() + .expect_err("ByteMessage cannot carry typed channel payloads"); + + assert!( + err.to_string() + .contains("Channel gates carry typed payloads") + ); + } + #[test] fn test_message_type() { // Create an empty message diff --git a/crates/pecos-engines/src/noise/biased_depolarizing.rs b/crates/pecos-engines/src/noise/biased_depolarizing.rs index db3f4ab2a..889cd6009 100644 --- a/crates/pecos-engines/src/noise/biased_depolarizing.rs +++ b/crates/pecos-engines/src/noise/biased_depolarizing.rs @@ -73,6 +73,13 @@ pub struct BiasedDepolarizingNoiseModel { impl ProbabilityValidator for BiasedDepolarizingNoiseModel {} impl BiasedDepolarizingNoiseModel { + fn channel_gate_error() -> PecosError { + PecosError::Input( + "ByteMessage noise models cannot process GateType::Channel; channel operations carry typed payloads and must use a channel-aware circuit path" + .to_string(), + ) + } + /// Create a new general noise model with the given probabilities #[must_use] pub fn new(p_prep: f64, p_meas_0: f64, p_meas_1: f64, p1: f64, p2: f64) -> Self { @@ -217,6 +224,9 @@ impl BiasedDepolarizingNoiseModel { trace!("Applying preparation with possible fault"); self.apply_prep_faults(&mut builder, gate); } + GateType::Channel => { + unreachable!("channel gates are rejected before noise is applied") + } GateType::I | GateType::Idle | GateType::MeasCrosstalkLocalPayload @@ -441,6 +451,9 @@ impl ControlEngine for BiasedDepolarizingNoiseModel { // Parse the input as quantum operations let gates: Vec = input.quantum_ops()?; + if gates.iter().any(Gate::is_channel) { + return Err(Self::channel_gate_error()); + } // Apply noise to the gates let noisy_gates = self.apply_noise_to_gates(&gates); diff --git a/crates/pecos-engines/src/noise/depolarizing.rs b/crates/pecos-engines/src/noise/depolarizing.rs index cb2f88e2f..91fccf32a 100644 --- a/crates/pecos-engines/src/noise/depolarizing.rs +++ b/crates/pecos-engines/src/noise/depolarizing.rs @@ -81,6 +81,13 @@ pub struct DepolarizingNoiseModel { impl ProbabilityValidator for DepolarizingNoiseModel {} impl DepolarizingNoiseModel { + fn channel_gate_error() -> PecosError { + PecosError::Input( + "ByteMessage noise models cannot process GateType::Channel; channel operations carry typed payloads and must use a channel-aware circuit path" + .to_string(), + ) + } + /// Compute a probability threshold from a f64 probability #[inline] fn compute_threshold(p: f64) -> u64 { @@ -231,6 +238,7 @@ impl DepolarizingNoiseModel { trace!("Applying preparation with possible fault"); Self::apply_prep_faults(rng, p_prep_threshold, builder, gate); } + GateType::Channel => unreachable!("channel gates are rejected before noise is applied"), GateType::I | GateType::Idle | GateType::MeasCrosstalkLocalPayload @@ -564,6 +572,15 @@ impl ControlEngine for DepolarizingNoiseModel { // For quantum operations, apply gate noise trace!("DepolarizingNoise::start - applying noise to quantum operations"); + self.scratch_gates.clear(); + input + .quantum_ops_into(&mut self.scratch_gates) + .map_err(|e| PecosError::Input(format!("Failed to parse quantum operations: {e}")))?; + + if self.scratch_gates.iter().any(Gate::is_channel) { + return Err(Self::channel_gate_error()); + } + if self.p_prep_threshold == 0 && self.p_meas_threshold == 0 && self.p1_threshold == 0 @@ -572,11 +589,6 @@ impl ControlEngine for DepolarizingNoiseModel { return Ok(EngineStage::NeedsProcessing(input)); } - self.scratch_gates.clear(); - input - .quantum_ops_into(&mut self.scratch_gates) - .map_err(|e| PecosError::Input(format!("Failed to parse quantum operations: {e}")))?; - self.scratch_builder.reset(); let _ = self.scratch_builder.for_quantum_operations(); diff --git a/crates/pecos-engines/src/noise/general.rs b/crates/pecos-engines/src/noise/general.rs index b3404751d..d64b4dde2 100644 --- a/crates/pecos-engines/src/noise/general.rs +++ b/crates/pecos-engines/src/noise/general.rs @@ -447,6 +447,11 @@ impl RngManageable for GeneralNoiseModel { impl ProbabilityValidator for GeneralNoiseModel {} impl GeneralNoiseModel { + fn channel_gate_error() -> String { + "ByteMessage noise models cannot process GateType::Channel; channel operations carry typed payloads and must use a channel-aware circuit path" + .to_string() + } + /// Create a new noise model with the specified error parameters /// /// Creates a `GeneralNoiseModel` with the specified error probabilities while using default values @@ -517,6 +522,9 @@ impl GeneralNoiseModel { let gates = input .quantum_ops() .expect("Failed to parse input as quantum operations"); + if gates.iter().any(Gate::is_channel) { + return Err(Self::channel_gate_error()); + } for gate in gates { // Track which qubits are being measured for leakage handling @@ -1560,6 +1568,7 @@ mod tests { qubits: vec![QubitId(qubit)].into(), params: vec![].into(), meas_ids: vec![].into(), + channel: None, }); } let measurement_request = request_builder.build(); @@ -1642,6 +1651,7 @@ mod tests { qubits: vec![QubitId(0)].into(), params: vec![].into(), meas_ids: vec![].into(), + channel: None, }; // Create a builder and apply noise @@ -1832,6 +1842,7 @@ mod tests { qubits: vec![QubitId(0)].into(), params: vec![].into(), meas_ids: vec![].into(), + channel: None, }; noise.apply_prep_faults(&prep_gate, &mut builder); @@ -2750,6 +2761,7 @@ mod tests { qubits: vec![QubitId(0)].into(), params: vec![1.0].into(), // 1 second duration meas_ids: vec![].into(), + channel: None, }; // Apply idle faults - should use coherent dephasing (RZ gates) @@ -2774,6 +2786,7 @@ mod tests { qubits: vec![QubitId(0), QubitId(1), QubitId(2)].into(), // 3 qubits params: vec![1.0].into(), // 1 second duration meas_ids: vec![].into(), + channel: None, }; model.apply_idle_faults( @@ -2911,6 +2924,7 @@ mod tests { qubits: vec![QubitId(0)].into(), params: vec![].into(), meas_ids: vec![].into(), + channel: None, }; // Create an X gate (not noiseless - should have noise applied) @@ -2920,6 +2934,7 @@ mod tests { qubits: vec![QubitId(0)].into(), params: vec![].into(), meas_ids: vec![].into(), + channel: None, }; // Make sure RZ is recognized as noiseless diff --git a/crates/pecos-engines/src/quantum.rs b/crates/pecos-engines/src/quantum.rs index c4aa06c15..512e6ff8f 100644 --- a/crates/pecos-engines/src/quantum.rs +++ b/crates/pecos-engines/src/quantum.rs @@ -4,6 +4,7 @@ use crate::byte_message::GateType; use dyn_clone::DynClone; use log::debug; use pecos_core::Angle64; +use pecos_core::ChannelExpr; use pecos_core::QubitId; use pecos_core::RngManageable; use pecos_core::errors::PecosError; @@ -54,6 +55,26 @@ fn flat_to_pairs(qubits: &[QubitId]) -> Vec<(QubitId, QubitId)> { pairs } +trait ChannelDispatch { + fn apply_channel_expr(&mut self, channel: &ChannelExpr) -> Result<(), PecosError>; +} + +impl ChannelDispatch for StabVec { + fn apply_channel_expr(&mut self, _channel: &ChannelExpr) -> Result<(), PecosError> { + Err(quantum_error( + "Channel gate requires a channel-aware simulator path", + )) + } +} + +impl ChannelDispatch for DensityMatrix { + fn apply_channel_expr(&mut self, channel: &ChannelExpr) -> Result<(), PecosError> { + DensityMatrix::apply_channel_expr(self, channel) + .map(|_| ()) + .map_err(|err| quantum_error(format!("invalid channel gate: {err}"))) + } +} + /// Process a `ByteMessage` against any Clifford-capable simulator. /// /// Shared gate dispatch for `SparseStabEngine`, `StabilizerEngine`, etc. @@ -274,7 +295,9 @@ fn process_clifford_message( +fn process_general_message< + S: CliffordGateable + ArbitraryRotationGateable + QuantumSimulator + ChannelDispatch, +>( sim: &mut S, message: &ByteMessage, ) -> Result { @@ -535,6 +558,12 @@ fn process_general_message { sim.pz(&cmd.qubits); } + GateType::Channel => { + let channel = cmd + .channel_expr() + .ok_or_else(|| quantum_error("Channel gate is missing its channel payload"))?; + sim.apply_channel_expr(channel)?; + } // No-ops GateType::I @@ -1094,6 +1123,11 @@ where debug!("Processing Prep gate on qubits {:?}", cmd.qubits); self.simulator.pz(&cmd.qubits); } + GateType::Channel => { + return Err(quantum_error( + "Channel gate requires a channel-aware simulator path", + )); + } GateType::I | GateType::Idle | GateType::MeasCrosstalkLocalPayload diff --git a/crates/pecos-qasm/src/engine.rs b/crates/pecos-qasm/src/engine.rs index 1e752de79..9a2ccba2a 100644 --- a/crates/pecos-qasm/src/engine.rs +++ b/crates/pecos-qasm/src/engine.rs @@ -651,7 +651,7 @@ impl QASMEngine { | GateType::SYY | GateType::SYYdg => self.process_two_qubit_gate(gate.gate_type, &qubits), // Gates not yet supported in QASM engine - GateType::SWAP | GateType::CCX | GateType::CRZ | GateType::CH => { + GateType::SWAP | GateType::CCX | GateType::CRZ | GateType::CH | GateType::Channel => { Err(PecosError::Processing(format!( "Gate type {:?} is not yet supported in the QASM engine", gate.gate_type diff --git a/crates/pecos-quantum/src/channel.rs b/crates/pecos-quantum/src/channel.rs index 52cf74006..81b07dadf 100644 --- a/crates/pecos-quantum/src/channel.rs +++ b/crates/pecos-quantum/src/channel.rs @@ -1278,6 +1278,30 @@ impl KrausOps { kraus_from_channel_expr_with_size(channel, num_qubits) } + /// Converts a symbolic channel expression to Kraus operators embedded in a + /// specific system size. + /// + /// Use this when applying a local channel to a larger simulator state: a + /// channel acting on qubit 3 of a 6-qubit system needs 6-qubit Kraus + /// matrices, not the minimal 4-qubit representation implied by the highest + /// touched qubit. + /// + /// # Errors + /// + /// Returns an error when the expression is unsupported, invalid, or touches + /// a qubit outside `num_qubits`. + pub fn from_channel_expr_with_num_qubits( + channel: &ChannelExpr, + num_qubits: usize, + ) -> Result { + for qubit in channel.qubits() { + if qubit >= num_qubits { + return Err(ChannelError::QubitOutOfRange { num_qubits, qubit }); + } + } + kraus_from_channel_expr_with_size(channel, num_qubits) + } + /// Converts this Kraus channel to a dense PTM. /// /// # Errors @@ -3365,6 +3389,22 @@ mod tests { assert!(compose_kraus.is_trace_preserving()); } + #[test] + fn kraus_from_channel_expr_can_embed_in_larger_system() { + let expr = pecos_core::channel::BitFlip(0.25, 2); + let kraus = KrausOps::from_channel_expr_with_num_qubits(&expr, 3).unwrap(); + + assert_eq!(kraus.num_qubits(), 3); + assert!(kraus.is_trace_preserving()); + assert!(matches!( + KrausOps::from_channel_expr_with_num_qubits(&expr, 2), + Err(ChannelError::QubitOutOfRange { + num_qubits: 2, + qubit: 2 + }) + )); + } + #[test] fn pauli_channel_conversion_ignores_global_pauli_phase() { let pauli = PauliString::from_paulis_with_phase(QuarterPhase::PlusI, &[Pauli::X]); diff --git a/crates/pecos-quantum/src/circuit_display.rs b/crates/pecos-quantum/src/circuit_display.rs index a2e61a01f..fe13ef9e0 100644 --- a/crates/pecos-quantum/src/circuit_display.rs +++ b/crates/pecos-quantum/src/circuit_display.rs @@ -74,6 +74,7 @@ fn gate_symbol(gate_type: GateType) -> &'static str { GateType::QFree => "QF", GateType::I | GateType::Idle => "I", GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload => "XT", + GateType::Channel => "Ch", GateType::Custom => "?", GateType::PauliOperatorMeta => "PO", } @@ -208,6 +209,7 @@ fn gate_color(gate_type: GateType) -> CellColor { | GateType::QAlloc | GateType::QFree | GateType::Custom + | GateType::Channel | GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload | GateType::CX diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index 03bcf578b..b93f47387 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -64,7 +64,7 @@ use pecos_core::gate_type::GateType; use pecos_core::{ - Angle64, Gate, GateMeasIds, GateQubits, GateSignature, MeasId, QubitId, TimeUnits, + Angle64, ChannelExpr, Gate, GateMeasIds, GateQubits, GateSignature, MeasId, QubitId, TimeUnits, }; use std::collections::{BTreeMap, BTreeSet}; @@ -462,6 +462,40 @@ pub struct TickCircuit { next_meas_record: usize, } +/// Maps an ideal circuit gate to zero or more channel annotations. +/// +/// [`TickCircuit::with_noise`] uses this trait to compile an ideal circuit into +/// an annotated circuit with explicit channel operations interleaved after the +/// ideal gates that triggered them. +pub trait GateNoiseModel { + /// Returns channel operations that should be placed after `gate`. + fn channels_after(&self, gate: &Gate) -> Vec; +} + +impl GateNoiseModel for F +where + F: Fn(&Gate) -> Vec, +{ + fn channels_after(&self, gate: &Gate) -> Vec { + self(gate) + } +} + +fn schedule_channel_gate(noise_ticks: &mut Vec, gate: Gate) { + let mut pending = Some(gate); + for tick in noise_ticks.iter_mut() { + let gate_ref = pending.as_ref().expect("pending gate is present"); + if tick.find_conflicts(&gate_ref.qubits).is_empty() { + tick.add_gate(pending.take().expect("pending gate is present")); + return; + } + } + + let mut tick = Tick::new(); + tick.add_gate(pending.expect("pending gate is present")); + noise_ticks.push(tick); +} + /// Handle to a specific tick for adding gates. /// /// Gates added through the handle are placed in the associated tick. @@ -809,6 +843,65 @@ impl TickCircuit { self.gate_signatures.clear(); } + /// Try to compile an ideal circuit plus a gate-triggered noise model into + /// an annotated circuit containing explicit channel operations. + /// + /// The original gates are preserved. For each source tick, channel + /// operations returned by `noise.channels_after(gate)` are scheduled into + /// one or more immediately following ticks while respecting qubit + /// conflicts. This produces a concrete inline representation useful for + /// inspection, visualization, and simulators that consume interleaved + /// channel operations directly. + /// # Errors + /// + /// Returns an error if the source circuit already contains channel + /// operations. Apply either inline channels or a noise model, not both. + pub fn try_with_noise(&self, noise: &N) -> Result { + if let Some((tick_idx, _)) = self + .iter_gates_with_tick() + .find(|(_, gate)| gate.is_channel()) + { + return Err(format!( + "with_noise cannot apply a noise model to a circuit that already contains channel operations (first channel at tick {tick_idx})" + )); + } + + let mut out = Self::new(); + out.circuit_attrs.clone_from(&self.circuit_attrs); + out.gate_signatures.clone_from(&self.gate_signatures); + out.annotations.clone_from(&self.annotations); + out.next_meas_record = self.next_meas_record; + + for tick in &self.ticks { + out.ticks.push(tick.clone()); + + let mut noise_ticks = Vec::new(); + for gate in tick.gates() { + for channel in noise.channels_after(gate) { + schedule_channel_gate(&mut noise_ticks, Gate::channel(channel)); + } + } + out.ticks.extend(noise_ticks); + } + + out.next_tick = out.ticks.len(); + Ok(out) + } + + /// Compile an ideal circuit plus a gate-triggered noise model into an + /// annotated circuit containing explicit channel operations. + /// + /// This is the convenience form of [`try_with_noise`](Self::try_with_noise). + /// + /// # Panics + /// + /// Panics if the source circuit already contains channel operations. + #[must_use] + pub fn with_noise(&self, noise: &N) -> Self { + self.try_with_noise(noise) + .expect("with_noise requires an ideal circuit without existing channel operations") + } + /// Reserve empty ticks in advance. /// /// This preallocates `n` empty ticks, which can be useful when you know @@ -1017,6 +1110,12 @@ impl TickCircuit { self.ticks.iter().flat_map(Tick::gates) } + /// Returns true if any tick contains an explicit channel operation. + #[must_use] + pub fn has_channel_operations(&self) -> bool { + self.iter_gates().any(Gate::is_channel) + } + /// Iterate over all gates with their tick index. /// /// Yields `(tick_index, gate)` pairs. @@ -1622,6 +1721,14 @@ impl<'a> TickHandle<'a> { self.add_gate(Gate::u(theta.into(), phi.into(), lambda.into(), qubits)) } + /// Place a typed channel operation in this tick. + /// + /// This is for annotated/noisy circuits. It does not use custom-gate + /// metadata; the channel payload is stored directly on the gate. + pub fn channel(&mut self, channel: ChannelExpr) -> &mut Self { + self.add_gate(Gate::channel(channel)) + } + // --- Two-qubit gates --- /// Apply CNOT (CX) gate(s) to one or more qubit pairs. @@ -2186,7 +2293,9 @@ impl From<&TickCircuit> for DagCircuit { | GateType::SZZ | GateType::SZZdg ); - let needs_split = if is_two_qubit { + let needs_split = if gate.is_channel() { + false + } else if is_two_qubit { gate.qubits.len() > 2 } else { gate.qubits.len() > 1 @@ -2216,6 +2325,7 @@ impl From<&TickCircuit> for DagCircuit { angles: gate.angles.clone(), params: gate.params.clone(), meas_ids: mr, + channel: gate.channel.clone(), } }) .collect() @@ -3433,6 +3543,103 @@ mod tests { assert!(count_after > count_before, "Should have added idle gates"); } + #[test] + fn test_channel_gate_is_first_class_tick_operation() { + let mut tc = TickCircuit::new(); + tc.tick() + .channel(pecos_core::channel::Depolarizing(0.25, 0)); + + let gate = &tc.get_tick(0).unwrap().gates()[0]; + assert_eq!(gate.gate_type, GateType::Channel); + assert_eq!(gate.qubits.as_slice(), &[QubitId::from(0)]); + assert!(gate.channel_expr().is_some()); + assert!(tc.has_channel_operations()); + assert!(gate.validate().is_ok()); + } + + #[test] + fn test_with_noise_inserts_channel_ticks() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[0]).x(&[1]); + tc.tick().cx(&[(0, 1)]); + + let noisy = tc.with_noise(&|gate: &Gate| { + gate.qubits + .iter() + .map(|q| pecos_core::channel::Depolarizing(0.01, q.index())) + .collect() + }); + + assert_eq!(noisy.num_ticks(), 4); + assert_eq!(noisy.get_tick(0).unwrap().gates()[0].gate_type, GateType::H); + assert!( + noisy + .get_tick(1) + .unwrap() + .gates() + .iter() + .all(Gate::is_channel) + ); + assert_eq!( + noisy.get_tick(2).unwrap().gates()[0].gate_type, + GateType::CX + ); + assert!( + noisy + .get_tick(3) + .unwrap() + .gates() + .iter() + .all(Gate::is_channel) + ); + } + + #[test] + fn test_with_noise_splits_conflicting_channel_ticks() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[0]); + + let noisy = tc.with_noise(&|_: &Gate| { + vec![ + pecos_core::channel::Depolarizing(0.01, 0), + pecos_core::channel::Dephasing(0.02, 0), + ] + }); + + assert_eq!(noisy.num_ticks(), 3); + assert_eq!(noisy.get_tick(0).unwrap().gates()[0].gate_type, GateType::H); + + let first_noise_tick = noisy.get_tick(1).unwrap(); + assert_eq!(first_noise_tick.gates().len(), 1); + assert!(first_noise_tick.gates()[0].is_channel()); + assert_eq!( + first_noise_tick.gates()[0].qubits.as_slice(), + &[QubitId::from(0)] + ); + + let second_noise_tick = noisy.get_tick(2).unwrap(); + assert_eq!(second_noise_tick.gates().len(), 1); + assert!(second_noise_tick.gates()[0].is_channel()); + assert_eq!( + second_noise_tick.gates()[0].qubits.as_slice(), + &[QubitId::from(0)] + ); + } + + #[test] + fn test_with_noise_rejects_existing_channel_operations() { + let mut tc = TickCircuit::new(); + tc.tick() + .channel(pecos_core::channel::Depolarizing(0.25, 0)); + + let err = tc + .try_with_noise(&|_: &Gate| vec![pecos_core::channel::Depolarizing(0.01, 0)]) + .unwrap_err(); + + assert!(err.contains("already contains channel operations")); + assert!(err.contains("tick 0")); + } + #[test] fn test_meas_record_idx_single_qubit() { let mut tc = TickCircuit::new(); diff --git a/crates/pecos-quantum/src/unitary_matrix.rs b/crates/pecos-quantum/src/unitary_matrix.rs index bdc53dcc3..f67310ebd 100644 --- a/crates/pecos-quantum/src/unitary_matrix.rs +++ b/crates/pecos-quantum/src/unitary_matrix.rs @@ -1929,6 +1929,7 @@ fn gate_to_matrix(gate_type: GateType, qubits: &[usize], num_qubits: usize) -> D GateType::Idle | GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload + | GateType::Channel | GateType::Custom | GateType::PauliOperatorMeta => { panic!("GateType::{gate_type:?} cannot be converted to a unitary matrix") diff --git a/crates/pecos-simulators/Cargo.toml b/crates/pecos-simulators/Cargo.toml index 160c8dffb..b4f4ac594 100644 --- a/crates/pecos-simulators/Cargo.toml +++ b/crates/pecos-simulators/Cargo.toml @@ -25,6 +25,7 @@ pecos-quantum.workspace = true pecos-random.workspace = true rand.workspace = true num-complex.workspace = true +nalgebra.workspace = true smallvec.workspace = true wide.workspace = true rayon = { version = "1.10", optional = true } diff --git a/crates/pecos-simulators/src/density_matrix.rs b/crates/pecos-simulators/src/density_matrix.rs index 6adbda50a..2ecb7695f 100644 --- a/crates/pecos-simulators/src/density_matrix.rs +++ b/crates/pecos-simulators/src/density_matrix.rs @@ -15,7 +15,9 @@ use super::clifford_gateable::{CliffordGateable, MeasurementResult}; use super::quantum_simulator::QuantumSimulator; use super::state_vec::StateVec; use super::state_vec_soa::StateVecSoA; -use pecos_core::{Angle64, QubitId, RngManageable}; +use nalgebra::DMatrix; +use pecos_core::{Angle64, ChannelExpr, QubitId, RngManageable}; +use pecos_quantum::{ChannelError, KrausOps}; use pecos_random::{PecosRng, Rng, RngExt, SeedableRng}; use core::fmt::{Debug, Display, Formatter, Write}; @@ -860,6 +862,73 @@ where self } + + /// Apply a symbolic channel expression to this density matrix. + /// + /// Supported expressions are those convertible to same-Hilbert-space Kraus + /// operators: unitary, mixed-unitary, amplitude damping, phase damping, + /// tensor, and composition. Erasure, leakage, and gate instruments are + /// intentionally rejected because they need extra flag/outcome semantics. + /// + /// # Errors + /// + /// Returns an error if the channel expression is unsupported or invalid for + /// this simulator's qubit count. + pub fn apply_channel_expr(&mut self, channel: &ChannelExpr) -> Result<&mut Self, ChannelError> { + let kraus = KrausOps::from_channel_expr_with_num_qubits(channel, self.num_physical_qubits)?; + self.apply_kraus_ops(&kraus) + } + + /// Apply Kraus operators to this density matrix. + /// + /// # Errors + /// + /// Returns an error if the Kraus operators are not defined on the same + /// number of qubits as this density matrix. + pub fn apply_kraus_ops(&mut self, kraus: &KrausOps) -> Result<&mut Self, ChannelError> { + let num_qubits_u32 = u32::try_from(self.num_physical_qubits).map_err(|_| { + ChannelError::DimensionOverflow { + num_qubits: self.num_physical_qubits, + } + })?; + let dim = 1usize + .checked_shl(num_qubits_u32) + .ok_or(ChannelError::DimensionOverflow { + num_qubits: self.num_physical_qubits, + })?; + if kraus.num_qubits() != self.num_physical_qubits { + let actual_qubits_u32 = + u32::try_from(kraus.num_qubits()).map_err(|_| ChannelError::DimensionOverflow { + num_qubits: kraus.num_qubits(), + })?; + let actual_dim = + 1usize + .checked_shl(actual_qubits_u32) + .ok_or(ChannelError::DimensionOverflow { + num_qubits: kraus.num_qubits(), + })?; + return Err(ChannelError::InvalidMatrixShape { + expected_rows: dim, + expected_cols: dim, + rows: actual_dim, + cols: actual_dim, + }); + } + + let rho = self.get_density_matrix(); + let flat: Vec = rho.iter().flat_map(|row| row.iter().copied()).collect(); + let rho_matrix = DMatrix::from_row_slice(dim, dim, &flat); + let mut evolved = DMatrix::zeros(dim, dim); + for operator in kraus.operators() { + evolved += operator * &rho_matrix * operator.adjoint(); + } + + let new_rho: Vec> = (0..dim) + .map(|row| (0..dim).map(|col| evolved[(row, col)]).collect()) + .collect(); + self.set_from_density_matrix(&new_rho); + Ok(self) + } } impl From<&StateVecSoA> for DensityMatrix @@ -1416,6 +1485,26 @@ mod tests { assert!(dm.is_pure()); } + #[test] + fn channel_expr_bit_flip_applies_to_density_matrix() { + let mut dm = DensityMatrix::new(1); + dm.apply_channel_expr(&pecos_core::channel::BitFlip(1.0, 0)) + .unwrap(); + + assert!(dm.probability(0) < 1e-10); + assert!((dm.probability(1) - 1.0).abs() < 1e-10); + } + + #[test] + fn channel_expr_embeds_local_channel_in_larger_density_matrix() { + let mut dm = DensityMatrix::new(2); + dm.apply_channel_expr(&pecos_core::channel::BitFlip(1.0, 1)) + .unwrap(); + + assert!(dm.probability(0) < 1e-10); + assert!((dm.probability(2) - 1.0).abs() < 1e-10); + } + #[test] fn state_vector_converts_to_density_matrix_and_back() { let mut state = StateVecSoA::new(2); diff --git a/crates/pecos-simulators/src/state_access.rs b/crates/pecos-simulators/src/state_access.rs index 6552041d3..674fda655 100644 --- a/crates/pecos-simulators/src/state_access.rs +++ b/crates/pecos-simulators/src/state_access.rs @@ -1018,7 +1018,7 @@ mod tests { let state = random_statevector(&mut rng, 2).unwrap(); p0_sum += state[0].norm_sqr(); } - let mean = p0_sum / samples as f64; + let mean = p0_sum / f64::from(samples); assert!( (0.22..0.28).contains(&mean), "expected E[|psi_0|^2] near 1/4 for a 4D Haar state, got {mean}" diff --git a/exp/pecos-eeg/examples/profile_heisenberg.rs b/exp/pecos-eeg/examples/profile_heisenberg.rs index f96ea235f..2f5d95bcd 100644 --- a/exp/pecos-eeg/examples/profile_heisenberg.rs +++ b/exp/pecos-eeg/examples/profile_heisenberg.rs @@ -15,6 +15,7 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), + channel: None, } } diff --git a/exp/pecos-eeg/src/circuit.rs b/exp/pecos-eeg/src/circuit.rs index 2f397f82a..fbc4fda73 100644 --- a/exp/pecos-eeg/src/circuit.rs +++ b/exp/pecos-eeg/src/circuit.rs @@ -377,6 +377,7 @@ mod tests { angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), + channel: None, } } diff --git a/exp/pecos-eeg/src/dem_mapping.rs b/exp/pecos-eeg/src/dem_mapping.rs index 725e2857f..8eca6bdb9 100644 --- a/exp/pecos-eeg/src/dem_mapping.rs +++ b/exp/pecos-eeg/src/dem_mapping.rs @@ -1465,6 +1465,7 @@ mod tests { angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), + channel: None, } } @@ -1520,6 +1521,7 @@ mod tests { angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), + channel: None, } } @@ -1579,6 +1581,7 @@ mod tests { angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), + channel: None, } } diff --git a/exp/pecos-eeg/src/expand.rs b/exp/pecos-eeg/src/expand.rs index 58991228c..b0d5a7b0f 100644 --- a/exp/pecos-eeg/src/expand.rs +++ b/exp/pecos-eeg/src/expand.rs @@ -259,6 +259,7 @@ pub fn make_gate(gt: GateType, qubits: &[usize]) -> Gate { angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), + channel: None, } } diff --git a/exp/pecos-eeg/src/heisenberg.rs b/exp/pecos-eeg/src/heisenberg.rs index 88a0cafcf..c68d9163b 100644 --- a/exp/pecos-eeg/src/heisenberg.rs +++ b/exp/pecos-eeg/src/heisenberg.rs @@ -2035,6 +2035,7 @@ mod tests { angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), + channel: None, } } diff --git a/exp/pecos-eeg/src/noise_compression.rs b/exp/pecos-eeg/src/noise_compression.rs index 3f47a1952..a2f09c2e7 100644 --- a/exp/pecos-eeg/src/noise_compression.rs +++ b/exp/pecos-eeg/src/noise_compression.rs @@ -255,6 +255,7 @@ fn forward_conjugate_label(label: &mut Bm, gate: &Gate) { angles: gate.angles.clone(), params: gate.params.clone(), meas_ids: gate.meas_ids.clone(), + channel: None, }; let mut sp = SparsePauli::from_bm(label); diff --git a/exp/pecos-eeg/src/stabilizer.rs b/exp/pecos-eeg/src/stabilizer.rs index 400b435ac..e4829fe32 100644 --- a/exp/pecos-eeg/src/stabilizer.rs +++ b/exp/pecos-eeg/src/stabilizer.rs @@ -148,6 +148,7 @@ mod tests { angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), + channel: None, } } diff --git a/exp/pecos-eeg/tests/beta_investigation.rs b/exp/pecos-eeg/tests/beta_investigation.rs index ec4d8b08e..e06084dcd 100644 --- a/exp/pecos-eeg/tests/beta_investigation.rs +++ b/exp/pecos-eeg/tests/beta_investigation.rs @@ -20,6 +20,7 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), + channel: None, } } diff --git a/exp/pecos-eeg/tests/generator_trace.rs b/exp/pecos-eeg/tests/generator_trace.rs index 1e0959ff8..2158b871a 100644 --- a/exp/pecos-eeg/tests/generator_trace.rs +++ b/exp/pecos-eeg/tests/generator_trace.rs @@ -24,6 +24,7 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), + channel: None, } } diff --git a/exp/pecos-eeg/tests/stabilizer_audit.rs b/exp/pecos-eeg/tests/stabilizer_audit.rs index dcc903cca..5e9fcea9c 100644 --- a/exp/pecos-eeg/tests/stabilizer_audit.rs +++ b/exp/pecos-eeg/tests/stabilizer_audit.rs @@ -19,6 +19,7 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), + channel: None, } } diff --git a/exp/pecos-eeg/tests/statevec_comparison.rs b/exp/pecos-eeg/tests/statevec_comparison.rs index cff1ff58b..ed387111f 100644 --- a/exp/pecos-eeg/tests/statevec_comparison.rs +++ b/exp/pecos-eeg/tests/statevec_comparison.rs @@ -27,6 +27,7 @@ fn gate(gt: GateType, qubits: &[usize]) -> Gate { angles: GateAngles::new(), params: GateParams::new(), meas_ids: pecos_core::GateMeasIds::new(), + channel: None, } } diff --git a/exp/pecos-experimental/src/hugr_executor.rs b/exp/pecos-experimental/src/hugr_executor.rs index b4c15ae04..9bdfa411b 100644 --- a/exp/pecos-experimental/src/hugr_executor.rs +++ b/exp/pecos-experimental/src/hugr_executor.rs @@ -318,6 +318,7 @@ where | GateType::CRZ | GateType::CH | GateType::CCX + | GateType::Channel | GateType::Custom => { return Err(HugrExecutionError::UnsupportedGate { gate_type: gate.gate_type, diff --git a/exp/pecos-neo/src/adapter.rs b/exp/pecos-neo/src/adapter.rs index 8f01c29f7..8dc2afcfb 100644 --- a/exp/pecos-neo/src/adapter.rs +++ b/exp/pecos-neo/src/adapter.rs @@ -139,15 +139,18 @@ fn convert_gate_type(core_type: CoreGateType) -> Option { } /// Convert a pecos-core `Gate` to a pecos-neo `GateCommand`. -/// -/// Returns `None` if the gate type is not supported. -fn convert_gate(gate: &Gate) -> Option { - let neo_type = convert_gate_type(gate.gate_type)?; +fn convert_gate(gate: &Gate) -> Result { + let neo_type = convert_gate_type(gate.gate_type).ok_or_else(|| { + pecos_core::errors::PecosError::Input(format!( + "pecos-neo adapter does not support gate type {:?}", + gate.gate_type + )) + })?; let qubits = gate.qubits.iter().copied().collect(); let angles = gate.angles.iter().copied().collect(); - Some(GateCommand { + Ok(GateCommand { gate_type: neo_type, qubits, angles, @@ -156,10 +159,9 @@ fn convert_gate(gate: &Gate) -> Option { /// Convert a `ByteMessage` containing quantum operations to a `CommandQueue`. /// -/// Skips any gates that can't be converted (with a warning in debug mode). -/// /// # Errors -/// Returns `PecosError` if the byte message cannot be decoded. +/// Returns `PecosError` if the byte message cannot be decoded or contains a +/// gate unsupported by the pecos-neo command representation. #[cfg(feature = "engines-adapter")] pub fn byte_message_to_command_queue( message: &pecos_engines::ByteMessage, @@ -169,9 +171,7 @@ pub fn byte_message_to_command_queue( let mut queue = CommandQueue::with_capacity(gates.len()); for gate in &gates { - if let Some(cmd) = convert_gate(gate) { - queue.push(cmd); - } + queue.push(convert_gate(gate)?); } Ok(queue) @@ -362,21 +362,27 @@ where /// /// This is useful when you have raw Gate objects and want to convert them /// to the pecos-neo format. -#[must_use] -pub fn gate_to_command(gate: &Gate) -> Option { +/// +/// # Errors +/// +/// Returns `PecosError` if the gate has no pecos-neo command representation. +pub fn gate_to_command(gate: &Gate) -> Result { convert_gate(gate) } /// Convert a slice of pecos-core Gates to a `CommandQueue`. -#[must_use] -pub fn gates_to_command_queue(gates: &[Gate]) -> CommandQueue { +/// +/// # Errors +/// +/// Returns `PecosError` if any gate has no pecos-neo command representation. +pub fn gates_to_command_queue( + gates: &[Gate], +) -> Result { let mut queue = CommandQueue::with_capacity(gates.len()); for gate in gates { - if let Some(cmd) = convert_gate(gate) { - queue.push(cmd); - } + queue.push(convert_gate(gate)?); } - queue + Ok(queue) } /// Convert a `CommandQueue` back to a Vec of pecos-core Gates. @@ -505,7 +511,7 @@ mod tests { Gate::new(CoreGateType::MZ, vec![], vec![], vec![QubitId(0)]), ]; - let queue = gates_to_command_queue(&gates); + let queue = gates_to_command_queue(&gates).expect("should convert"); assert_eq!(queue.len(), 3); } @@ -521,11 +527,23 @@ mod tests { ), ]; - let queue = gates_to_command_queue(&original_gates); + let queue = gates_to_command_queue(&original_gates).expect("should convert"); let back = command_queue_to_gates(&queue); assert_eq!(back.len(), 2); assert_eq!(back[0].gate_type, CoreGateType::H); assert_eq!(back[1].gate_type, CoreGateType::CX); } + + #[test] + fn test_gate_to_command_rejects_channel_gate() { + let gate = Gate::channel(pecos_core::channel::Depolarizing(0.01, 0)); + + let err = gate_to_command(&gate).expect_err("channel gates need typed channel handling"); + + assert!( + err.to_string() + .contains("does not support gate type Channel") + ); + } } diff --git a/exp/pecos-neo/src/circuit.rs b/exp/pecos-neo/src/circuit.rs index c4d802adc..e53a86f03 100644 --- a/exp/pecos-neo/src/circuit.rs +++ b/exp/pecos-neo/src/circuit.rs @@ -46,7 +46,6 @@ use smallvec::SmallVec; // ============================================================================ impl From for GateType { - #[allow(clippy::match_same_arms)] // Unknown gate types explicitly map to I fn from(gt: pecos_core::gate_type::GateType) -> Self { use pecos_core::gate_type::GateType as CoreGT; match gt { @@ -73,6 +72,10 @@ impl From for GateType { CoreGT::CX => Self::CX, CoreGT::CY => Self::CY, CoreGT::CZ => Self::CZ, + CoreGT::SXX => Self::SXX, + CoreGT::SXXdg => Self::SXXdg, + CoreGT::SYY => Self::SYY, + CoreGT::SYYdg => Self::SYYdg, CoreGT::SZZ => Self::SZZ, CoreGT::SZZdg => Self::SZZdg, CoreGT::SWAP => Self::SWAP, @@ -88,8 +91,7 @@ impl From for GateType { CoreGT::QAlloc => Self::QAlloc, CoreGT::QFree => Self::QFree, CoreGT::Idle => Self::Idle, - // Any unknown gate types default to identity - _ => Self::I, + other => panic!("unsupported pecos-core gate type for pecos-neo conversion: {other:?}"), } } } @@ -297,9 +299,10 @@ impl From<&CommandQueue> for TickCircuit { params: SmallVec::new(), qubits: qubit_ids, meas_ids: SmallVec::new(), + channel: None, }; - // Use try_add_gate and ignore errors (shouldn't happen with one gate per tick) - let _ = tick.try_add_gate(gate); + tick.try_add_gate(gate) + .expect("one gate per tick should not have qubit conflicts"); } } } @@ -429,6 +432,7 @@ mod tests { params: SmallVec::new(), qubits: smallvec::smallvec![QubitId(0)], meas_ids: SmallVec::new(), + channel: None, }; let cmd: GateCommand = (&gate).into(); diff --git a/python/pecos-rslib-exp/src/eeg_bindings.rs b/python/pecos-rslib-exp/src/eeg_bindings.rs index 3685b8ca1..110642764 100644 --- a/python/pecos-rslib-exp/src/eeg_bindings.rs +++ b/python/pecos-rslib-exp/src/eeg_bindings.rs @@ -1141,6 +1141,7 @@ fn extract_gates(py_tc: &Bound<'_, PyAny>) -> PyResult> { angles: GateAngles::new(), params: GateParams::new(), meas_ids: GateMeasIds::new(), + channel: None, }); } } @@ -1169,6 +1170,7 @@ fn extract_gates(py_tc: &Bound<'_, PyAny>) -> PyResult> { angles: GateAngles::new(), params: GateParams::new(), meas_ids: GateMeasIds::new(), + channel: None, }); } } @@ -1181,6 +1183,7 @@ fn extract_gates(py_tc: &Bound<'_, PyAny>) -> PyResult> { angles: GateAngles::new(), params: GateParams::new(), meas_ids: GateMeasIds::new(), + channel: None, }); } } @@ -1202,6 +1205,7 @@ fn extract_gates(py_tc: &Bound<'_, PyAny>) -> PyResult> { angles: GateAngles::new(), params: GateParams::new(), meas_ids: GateMeasIds::new(), + channel: None, }; if gt == pecos_core::gate_type::GateType::RZ && let Ok(angles) = gate.getattr("angles")?.extract::>() diff --git a/python/pecos-rslib-exp/src/sim_neo_bindings.rs b/python/pecos-rslib-exp/src/sim_neo_bindings.rs index 15186eff8..923a7c653 100644 --- a/python/pecos-rslib-exp/src/sim_neo_bindings.rs +++ b/python/pecos-rslib-exp/src/sim_neo_bindings.rs @@ -767,6 +767,7 @@ fn commands_to_gates(commands: &pecos_neo::command::CommandQueue) -> Vec Date: Sun, 10 May 2026 12:58:18 -0600 Subject: [PATCH 088/125] Add inline channel execution for sim_neo --- Cargo.toml | 9 +- crates/pecos-core/src/unitary_rep.rs | 19 + exp/pecos-lindblad/Cargo.toml | 4 +- exp/pecos-neo/src/inline_channel.rs | 581 ++++++++++++++++++ exp/pecos-neo/src/lib.rs | 1 + .../pecos-rslib-exp/src/sim_neo_bindings.rs | 87 ++- .../pecos-rslib/src/dag_circuit_bindings.rs | 193 +++++- .../tests/qec/test_inline_channel_sim_neo.py | 74 +++ 8 files changed, 958 insertions(+), 10 deletions(-) create mode 100644 exp/pecos-neo/src/inline_channel.rs create mode 100644 python/quantum-pecos/tests/qec/test_inline_channel_sim_neo.py diff --git a/Cargo.toml b/Cargo.toml index c70013598..0f10afafb 100644 --- a/Cargo.toml +++ b/Cargo.toml @@ -151,13 +151,16 @@ assert_cmd = "2" criterion = "0.8" paste = "1" random_tester = "0.1" +proptest = "1" # --- ZX calculus --- quizx = "0.3" # --- Decoder libraries --- fusion-blossom = "0.2" -mwpf = { git = "https://github.com/yuewuo/mwpf", tag = "v0.2.12", default-features = false, features = ["f64_weight"] } +mwpf = { git = "https://github.com/yuewuo/mwpf", tag = "v0.2.12", default-features = false, features = [ + "f64_weight", +] } relay-bp = "0.2" # ndarray 0.16 for relay-bp compat (relay-bp uses ndarray 0.16, PECOS uses 0.17) ndarray-016 = { package = "ndarray", version = "0.16" } @@ -232,7 +235,7 @@ strip = true # Strip debug symbols for smaller binaries [profile.profiling] inherits = "release" strip = false -debug = 1 # line tables only — minimal size impact +debug = 1 # line tables only — minimal size impact # Native profile: release + CPU-specific optimizations # Use with: cargo build --profile native @@ -252,4 +255,4 @@ multiple-crate-versions = "allow" # Physics/math code uses short, domain-standard variable names (sx/sz, x/z/r/s/p) similar-names = "allow" many-single-char-names = "allow" -too-many-lines = "allow" # ~114 hits across 11 crates -- sim algorithms, tests, benchmarks +too-many-lines = "allow" # ~114 hits across 11 crates -- sim algorithms, tests, benchmarks diff --git a/crates/pecos-core/src/unitary_rep.rs b/crates/pecos-core/src/unitary_rep.rs index 610d86ff9..d86c3d6cf 100644 --- a/crates/pecos-core/src/unitary_rep.rs +++ b/crates/pecos-core/src/unitary_rep.rs @@ -1450,6 +1450,10 @@ impl UnitaryRep { }, qubits, ) => { + if angle == Angle64::ZERO { + return Some(PauliString::identity()); + } + // Only half-turn rotations are Pauli operators let half = Angle64::HALF_TURN; let neg_half = negate_angle(half); @@ -4218,6 +4222,21 @@ mod tests { } } + #[test] + fn test_try_to_pauli_string_zero_rotation_is_identity() { + for unitary in [ + I(0), + RX(Angle64::ZERO, 0), + RY(Angle64::ZERO, 1), + RZ(Angle64::ZERO, 2), + ] { + let ps = unitary + .try_to_pauli_string() + .expect("zero rotation should convert to identity Pauli"); + assert_eq!(ps.weight(), 0); + } + } + #[test] fn test_try_to_pauli_non_pauli() { // Quarter-turn rotations should not convert diff --git a/exp/pecos-lindblad/Cargo.toml b/exp/pecos-lindblad/Cargo.toml index 683ed1cca..b91b7c1ad 100644 --- a/exp/pecos-lindblad/Cargo.toml +++ b/exp/pecos-lindblad/Cargo.toml @@ -26,8 +26,8 @@ rand.workspace = true serde = { workspace = true, optional = true } [dev-dependencies] -approx = "0.5" +approx.workspace = true pecos-qec.workspace = true -proptest = "1.4" +proptest.workspace = true rand.workspace = true serde_json.workspace = true diff --git a/exp/pecos-neo/src/inline_channel.rs b/exp/pecos-neo/src/inline_channel.rs new file mode 100644 index 000000000..58524443c --- /dev/null +++ b/exp/pecos-neo/src/inline_channel.rs @@ -0,0 +1,581 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Execution helpers for `TickCircuit`s containing inline channel gates. +//! +//! These routines consume the concrete channel operations inserted into a +//! `TickCircuit`, rather than adding a separate event-driven noise model at +//! execution time. + +use pecos_core::gate_type::GateType; +use pecos_core::{Angle64, ChannelExpr, Gate, Pauli, PauliOperator, PauliString, QubitId}; +use pecos_quantum::TickCircuit; +use pecos_random::{PecosRng, RngExt}; +use pecos_simulators::{ArbitraryRotationGateable, CliffordGateable, DensityMatrix, SparseStab}; +use thiserror::Error; + +const PROBABILITY_SUM_TOLERANCE: f64 = 1e-9; + +/// Error returned while executing a circuit with inline channel gates. +#[derive(Debug, Error)] +pub enum InlineChannelError { + /// A `Channel` gate had no channel payload. + #[error("Channel gate missing channel payload")] + MissingChannelPayload, + + /// A two-qubit gate was given an odd number of qubits. + #[error("{gate_type:?} requires an even number of qubits, got {qubit_count}")] + InvalidPairArity { + gate_type: GateType, + qubit_count: usize, + }, + + /// A parameterized gate was missing one of its angle parameters. + #[error("{gate_type:?} is missing angle parameter {index}")] + MissingAngle { gate_type: GateType, index: usize }, + + /// Density-matrix execution does not support this gate on the inline path. + #[error("DensityMatrix inline-channel path does not support gate {gate_type:?}")] + UnsupportedDensityMatrixGate { gate_type: GateType }, + + /// Stabilizer execution does not support this gate on the inline path. + #[error("stabilizer inline-channel path does not support non-Clifford gate {gate_type:?}")] + UnsupportedStabilizerGate { gate_type: GateType }, + + /// The stabilizer backend was asked to sample a non-Pauli channel. + #[error("stabilizer backend can only sample inline Pauli channels")] + NonPauliChannel, + + /// The stabilizer backend was asked to sample a channel that is not a Pauli mixed-unitary. + #[error("stabilizer backend can only sample inline Pauli mixed-unitary channels")] + NonPauliMixedUnitaryChannel, + + /// A mixed-unitary channel had invalid probabilities. + #[error("channel probabilities must be non-negative and sum to 1")] + InvalidProbabilities, + + /// Probability validation passed, but random sampling still missed every term. + #[error("Pauli channel sampling failed after probability validation")] + SamplingMiss, + + /// `DensityMatrix` rejected a channel expression. + #[error("channel application failed: {0}")] + ChannelApplication(String), +} + +/// Return the number of qubits needed to simulate the circuit. +#[must_use] +pub fn tick_circuit_num_qubits(circuit: &TickCircuit) -> usize { + circuit + .all_qubits() + .into_iter() + .map(|q| q.index() + 1) + .max() + .unwrap_or(0) +} + +/// Execute an inline-channel `TickCircuit` using a density matrix simulator. +/// +/// This path supports arbitrary channel expressions accepted by +/// [`DensityMatrix::apply_channel_expr`], and also supports the standard +/// unitary gates implemented by the density matrix simulator. +/// +/// # Errors +/// +/// Returns [`InlineChannelError`] when a channel payload is malformed, when a +/// gate has invalid arity or missing parameters, or when the density matrix +/// backend does not support a gate/channel. +pub fn run_inline_channels_density_matrix( + circuit: &TickCircuit, + shots: usize, + seed: u64, +) -> Result>, InlineChannelError> { + let num_qubits = tick_circuit_num_qubits(circuit); + let mut rows = Vec::with_capacity(shots); + + for shot in 0..shots { + let shot_seed = seed.wrapping_add(shot as u64); + let mut sim = DensityMatrix::with_seed(num_qubits, shot_seed); + let mut row = Vec::new(); + + for tick in circuit.ticks() { + for gate in tick.gates() { + row.extend(apply_gate_to_density_matrix(&mut sim, gate)?); + } + } + + rows.push(row); + } + + Ok(rows) +} + +/// Execute an inline-channel `TickCircuit` using a stabilizer simulator. +/// +/// This path supports Clifford gates plus channel gates whose payloads are +/// Pauli or Pauli mixed-unitary channels. Non-Pauli channels are rejected +/// explicitly. +/// +/// # Errors +/// +/// Returns [`InlineChannelError`] for unsupported gates, malformed channel +/// probabilities, non-Pauli channels, invalid arity, or missing gate +/// parameters. +pub fn run_inline_pauli_channels_stabilizer( + circuit: &TickCircuit, + shots: usize, + seed: u64, +) -> Result>, InlineChannelError> { + let num_qubits = tick_circuit_num_qubits(circuit); + let mut rows = Vec::with_capacity(shots); + + for shot in 0..shots { + let shot_seed = seed.wrapping_add(shot as u64); + let mut sim = SparseStab::with_seed(num_qubits, shot_seed); + let mut rng = PecosRng::seed_from_u64(shot_seed ^ 0x5eed_5eed_5eed_5eed); + let mut row = Vec::new(); + + for tick in circuit.ticks() { + for gate in tick.gates() { + row.extend(apply_gate_to_stabilizer_with_pauli_channels( + &mut sim, gate, &mut rng, + )?); + } + } + + rows.push(row); + } + + Ok(rows) +} + +fn qubit_pairs( + qubits: &[QubitId], + gate_type: GateType, +) -> Result, InlineChannelError> { + if !qubits.len().is_multiple_of(2) { + return Err(InlineChannelError::InvalidPairArity { + gate_type, + qubit_count: qubits.len(), + }); + } + Ok(qubits + .chunks_exact(2) + .map(|pair| (pair[0], pair[1])) + .collect()) +} + +fn gate_angle(gate: &Gate, index: usize) -> Result { + gate.angles + .get(index) + .copied() + .ok_or(InlineChannelError::MissingAngle { + gate_type: gate.gate_type, + index, + }) +} + +fn apply_gate_to_density_matrix( + sim: &mut DensityMatrix, + gate: &Gate, +) -> Result, InlineChannelError> { + let qubits = gate.qubits.as_slice(); + match gate.gate_type { + GateType::Channel => { + let channel = gate + .channel_expr() + .ok_or(InlineChannelError::MissingChannelPayload)?; + sim.apply_channel_expr(channel) + .map_err(|e| InlineChannelError::ChannelApplication(e.to_string()))?; + Ok(Vec::new()) + } + GateType::PZ | GateType::QAlloc => { + sim.pz(qubits); + Ok(Vec::new()) + } + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked => Ok(sim + .mz(qubits) + .into_iter() + .map(|r| u8::from(r.outcome)) + .collect()), + GateType::I | GateType::Idle => Ok(Vec::new()), + GateType::X => { + sim.x(qubits); + Ok(Vec::new()) + } + GateType::Y => { + sim.y(qubits); + Ok(Vec::new()) + } + GateType::Z => { + sim.z(qubits); + Ok(Vec::new()) + } + GateType::H => { + sim.h(qubits); + Ok(Vec::new()) + } + GateType::F => { + sim.f(qubits); + Ok(Vec::new()) + } + GateType::Fdg => { + sim.fdg(qubits); + Ok(Vec::new()) + } + GateType::SX => { + sim.sx(qubits); + Ok(Vec::new()) + } + GateType::SXdg => { + sim.sxdg(qubits); + Ok(Vec::new()) + } + GateType::SY => { + sim.sy(qubits); + Ok(Vec::new()) + } + GateType::SYdg => { + sim.sydg(qubits); + Ok(Vec::new()) + } + GateType::SZ => { + sim.sz(qubits); + Ok(Vec::new()) + } + GateType::SZdg => { + sim.szdg(qubits); + Ok(Vec::new()) + } + GateType::CX => { + sim.cx(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::CY => { + sim.cy(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::CZ => { + sim.cz(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SXX => { + sim.sxx(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SXXdg => { + sim.sxxdg(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SYY => { + sim.syy(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SYYdg => { + sim.syydg(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SZZ => { + sim.szz(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SZZdg => { + sim.szzdg(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SWAP => { + sim.swap(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::T => { + sim.t(qubits); + Ok(Vec::new()) + } + GateType::Tdg => { + sim.tdg(qubits); + Ok(Vec::new()) + } + GateType::RX => { + sim.rx(gate_angle(gate, 0)?, qubits); + Ok(Vec::new()) + } + GateType::RY => { + sim.ry(gate_angle(gate, 0)?, qubits); + Ok(Vec::new()) + } + GateType::RZ => { + sim.rz(gate_angle(gate, 0)?, qubits); + Ok(Vec::new()) + } + GateType::U => { + sim.u( + gate_angle(gate, 0)?, + gate_angle(gate, 1)?, + gate_angle(gate, 2)?, + qubits, + ); + Ok(Vec::new()) + } + GateType::R1XY => { + sim.r1xy(gate_angle(gate, 0)?, gate_angle(gate, 1)?, qubits); + Ok(Vec::new()) + } + GateType::RXX => { + sim.rxx(gate_angle(gate, 0)?, &qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::RYY => { + sim.ryy(gate_angle(gate, 0)?, &qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::RZZ => { + sim.rzz(gate_angle(gate, 0)?, &qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + gate_type => Err(InlineChannelError::UnsupportedDensityMatrixGate { gate_type }), + } +} + +fn apply_pauli_string_to_stabilizer(sim: &mut SparseStab, pauli: &PauliString) { + for (p, q) in pauli.paulis() { + match p { + Pauli::I => {} + Pauli::X => { + sim.x(&[*q]); + } + Pauli::Y => { + sim.y(&[*q]); + } + Pauli::Z => { + sim.z(&[*q]); + } + } + } +} + +fn sample_pauli_channel( + channel: &ChannelExpr, + rng: &mut PecosRng, +) -> Result, InlineChannelError> { + let ops = match channel { + ChannelExpr::Unitary(unitary) => { + let pauli = unitary + .clone() + .try_to_pauli_string() + .ok_or(InlineChannelError::NonPauliChannel)?; + return Ok((pauli.weight() > 0).then_some(pauli)); + } + ChannelExpr::MixedUnitary(ops) => ops, + _ => return Err(InlineChannelError::NonPauliMixedUnitaryChannel), + }; + + let total: f64 = ops.iter().map(|(p, _)| *p).sum(); + if (total - 1.0).abs() > PROBABILITY_SUM_TOLERANCE || ops.iter().any(|(p, _)| *p < 0.0) { + return Err(InlineChannelError::InvalidProbabilities); + } + + let mut threshold = rng.random::() * total; + for (prob, unitary) in ops { + if threshold < *prob { + let pauli = unitary + .clone() + .try_to_pauli_string() + .ok_or(InlineChannelError::NonPauliChannel)?; + return Ok((pauli.weight() > 0).then_some(pauli)); + } + threshold -= *prob; + } + + Err(InlineChannelError::SamplingMiss) +} + +fn apply_gate_to_stabilizer_with_pauli_channels( + sim: &mut SparseStab, + gate: &Gate, + rng: &mut PecosRng, +) -> Result, InlineChannelError> { + let qubits = gate.qubits.as_slice(); + match gate.gate_type { + GateType::Channel => { + let channel = gate + .channel_expr() + .ok_or(InlineChannelError::MissingChannelPayload)?; + if let Some(pauli) = sample_pauli_channel(channel, rng)? { + apply_pauli_string_to_stabilizer(sim, &pauli); + } + Ok(Vec::new()) + } + GateType::PZ | GateType::QAlloc => { + sim.pz(qubits); + Ok(Vec::new()) + } + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked => Ok(sim + .mz(qubits) + .into_iter() + .map(|r| u8::from(r.outcome)) + .collect()), + GateType::I | GateType::Idle => Ok(Vec::new()), + GateType::X => { + sim.x(qubits); + Ok(Vec::new()) + } + GateType::Y => { + sim.y(qubits); + Ok(Vec::new()) + } + GateType::Z => { + sim.z(qubits); + Ok(Vec::new()) + } + GateType::H => { + sim.h(qubits); + Ok(Vec::new()) + } + GateType::F => { + sim.f(qubits); + Ok(Vec::new()) + } + GateType::Fdg => { + sim.fdg(qubits); + Ok(Vec::new()) + } + GateType::SX => { + sim.sx(qubits); + Ok(Vec::new()) + } + GateType::SXdg => { + sim.sxdg(qubits); + Ok(Vec::new()) + } + GateType::SY => { + sim.sy(qubits); + Ok(Vec::new()) + } + GateType::SYdg => { + sim.sydg(qubits); + Ok(Vec::new()) + } + GateType::SZ => { + sim.sz(qubits); + Ok(Vec::new()) + } + GateType::SZdg => { + sim.szdg(qubits); + Ok(Vec::new()) + } + GateType::CX => { + sim.cx(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::CY => { + sim.cy(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::CZ => { + sim.cz(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SXX => { + sim.sxx(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SXXdg => { + sim.sxxdg(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SYY => { + sim.syy(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SYYdg => { + sim.syydg(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SZZ => { + sim.szz(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SZZdg => { + sim.szzdg(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + GateType::SWAP => { + sim.swap(&qubit_pairs(qubits, gate.gate_type)?); + Ok(Vec::new()) + } + gate_type => Err(InlineChannelError::UnsupportedStabilizerGate { gate_type }), + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn density_matrix_inline_bit_flip_channel_flips_measurement() { + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[0]); + circuit.tick().channel(pecos_core::channel::BitFlip(1.0, 0)); + circuit.tick().mz(&[0]); + + let rows = run_inline_channels_density_matrix(&circuit, 3, 123).unwrap(); + + assert_eq!(rows, vec![vec![1], vec![1], vec![1]]); + } + + #[test] + fn stabilizer_inline_pauli_channel_flips_measurement() { + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[0]); + circuit.tick().channel(pecos_core::channel::BitFlip(1.0, 0)); + circuit.tick().mz(&[0]); + + let rows = run_inline_pauli_channels_stabilizer(&circuit, 3, 123).unwrap(); + + assert_eq!(rows, vec![vec![1], vec![1], vec![1]]); + } + + #[test] + fn stabilizer_inline_channel_rejects_non_clifford_gate() { + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[0]); + circuit.tick().t(&[0]); + circuit.tick().channel(pecos_core::channel::BitFlip(0.5, 0)); + circuit.tick().mz(&[0]); + + let err = run_inline_pauli_channels_stabilizer(&circuit, 1, 123).unwrap_err(); + + assert!(matches!( + err, + InlineChannelError::UnsupportedStabilizerGate { + gate_type: GateType::T + } + )); + } + + #[test] + fn stabilizer_inline_channel_rejects_non_pauli_channel() { + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[0]); + circuit + .tick() + .channel(pecos_core::channel::AmplitudeDamping(0.5, 0)); + circuit.tick().mz(&[0]); + + let err = run_inline_pauli_channels_stabilizer(&circuit, 1, 123).unwrap_err(); + + assert!(matches!( + err, + InlineChannelError::NonPauliMixedUnitaryChannel + )); + } +} diff --git a/exp/pecos-neo/src/lib.rs b/exp/pecos-neo/src/lib.rs index 7c309e8d4..e9296bdb9 100644 --- a/exp/pecos-neo/src/lib.rs +++ b/exp/pecos-neo/src/lib.rs @@ -149,6 +149,7 @@ pub mod command; pub mod ecs; pub mod engines; pub mod extensible; +pub mod inline_channel; pub mod noise; pub mod outcome; pub mod program; diff --git a/python/pecos-rslib-exp/src/sim_neo_bindings.rs b/python/pecos-rslib-exp/src/sim_neo_bindings.rs index 923a7c653..666784395 100644 --- a/python/pecos-rslib-exp/src/sim_neo_bindings.rs +++ b/python/pecos-rslib-exp/src/sim_neo_bindings.rs @@ -22,7 +22,7 @@ //! .run()) //! ``` -use pecos_core::{Angle64, PauliString}; +use pecos_core::{Angle64, ChannelExpr, Gate, Pauli, PauliString, QuarterPhase, QubitId}; use pecos_neo::command::CommandBuilder; use pecos_neo::noise::{ ComposableNoiseModel, MeasurementChannel, PreparationChannel, SingleQubitChannel, @@ -547,6 +547,10 @@ impl PySimNeoBuilder { /// All backends return `RawMeasurementResult` which supports: /// `result[shot]`, `result.get(shot, meas)`, `len(result)`, iteration. fn run(&self) -> PyResult { + if self.tick_circuit.has_channel_operations() { + return self.run_inline_channel_circuit(); + } + if self.backend == "meas_sampling" { return self.run_meas_sampling(); } @@ -597,6 +601,48 @@ impl PySimNeoBuilder { } impl PySimNeoBuilder { + fn run_inline_channel_circuit(&self) -> PyResult { + if self.noise_config.is_some() { + return Err(pyo3::exceptions::PyValueError::new_err( + "sim_neo received a TickCircuit with inline channel operations; do not also pass .noise()", + )); + } + + match self.backend.as_str() { + "statevec" => self.run_inline_channel_density_matrix(), + "stabilizer" => self.run_inline_pauli_channel_stabilizer(), + "stabmps" => Err(pyo3::exceptions::PyValueError::new_err( + "stab_mps backend does not support inline channel operations; use statevec()/default for density-matrix execution", + )), + "meas_sampling" => Err(pyo3::exceptions::PyValueError::new_err( + "meas_sampling backend builds its own measurement model and does not consume inline channel operations", + )), + other => Err(pyo3::exceptions::PyValueError::new_err(format!( + "Unknown backend: {other}" + ))), + } + } + + fn run_inline_channel_density_matrix(&self) -> PyResult { + let rows = pecos_neo::inline_channel::run_inline_channels_density_matrix( + &self.tick_circuit, + self.shots, + self.seed, + ) + .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))?; + Ok(PyRawMeasurementResult::from_rows(rows)) + } + + fn run_inline_pauli_channel_stabilizer(&self) -> PyResult { + let rows = pecos_neo::inline_channel::run_inline_pauli_channels_stabilizer( + &self.tick_circuit, + self.shots, + self.seed, + ) + .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))?; + Ok(PyRawMeasurementResult::from_rows(rows)) + } + /// DEM sampling backend: dispatches to stochastic or coherent path based on method. fn run_meas_sampling(&self) -> PyResult { let noise_config = self.noise_config.as_ref().ok_or_else(|| { @@ -749,7 +795,7 @@ impl PySimNeoBuilder { /// Convert CommandQueue to Vec for EEG analysis. fn commands_to_gates(commands: &pecos_neo::command::CommandQueue) -> Vec { - use pecos_core::{Gate, GateAngles, GateMeasIds, GateParams}; + use pecos_core::{GateAngles, GateMeasIds, GateParams}; commands .iter() @@ -789,11 +835,14 @@ fn commands_to_gates(commands: &pecos_neo::command::CommandQueue) -> Vec) -> PyResult { - let commands = extract_commands(tick_circuit)?; - // Build a Rust TickCircuit from the Python object. // This is the canonical circuit representation used by DemSampler. let tc = build_rust_tick_circuit(tick_circuit)?; + let commands = if tc.has_channel_operations() { + pecos_neo::command::CommandQueue::new() + } else { + extract_commands(tick_circuit)? + }; Ok(PySimNeoBuilder { commands, @@ -999,6 +1048,32 @@ fn parse_python_pauli_string(text: &str) -> Option { )) } +fn channel_expr_from_python_gate(gate: &Bound<'_, PyAny>) -> PyResult { + let terms: Vec<(f64, Vec<(String, usize)>)> = + gate.call_method0("channel_mixed_pauli_terms")?.extract()?; + let mut ops = Vec::with_capacity(terms.len()); + for (probability, terms) in terms { + let mut paulis = Vec::with_capacity(terms.len()); + for (label, qubit) in terms { + let pauli = match label.as_str() { + "I" => continue, + "X" => Pauli::X, + "Y" => Pauli::Y, + "Z" => Pauli::Z, + other => { + return Err(pyo3::exceptions::PyValueError::new_err(format!( + "unsupported channel Pauli label {other:?}" + ))); + } + }; + paulis.push((pauli, QubitId(qubit))); + } + let pauli_string = PauliString::with_phase_and_paulis(QuarterPhase::PlusOne, paulis); + ops.push((probability, pecos_core::UnitaryRep::from(pauli_string))); + } + Ok(ChannelExpr::MixedUnitary(ops)) +} + /// Create detector or observable annotations from JSON metadata. fn create_annotations_from_json( tc: &mut pecos_quantum::TickCircuit, @@ -1037,6 +1112,10 @@ fn build_gate_from_python( use pecos_core::gate_type::GateType; use pecos_core::{Gate, GateAngles, GateMeasIds, GateParams}; + if gate_name == "Channel" { + return Ok(Gate::channel(channel_expr_from_python_gate(gate)?)); + } + let gate_type = match gate_name { "H" => GateType::H, "X" => GateType::X, diff --git a/python/pecos-rslib/src/dag_circuit_bindings.rs b/python/pecos-rslib/src/dag_circuit_bindings.rs index 9b95b7547..8c4174ead 100644 --- a/python/pecos-rslib/src/dag_circuit_bindings.rs +++ b/python/pecos-rslib/src/dag_circuit_bindings.rs @@ -24,11 +24,86 @@ use crate::dtypes::AngleParam; use crate::gate_registry_bindings::PyGateRegistry; -use pecos_core::{Angle64, GateQubits, GateSignature, TimeUnits}; +use pecos_core::{Angle64, ChannelExpr, GateQubits, GateSignature, Pauli, TimeUnits}; use pecos_quantum::{Attribute, DagCircuit, Gate, GateType, QubitId, Tick, TickCircuit}; use pyo3::prelude::*; use pyo3::types::{PyBytes, PyDict, PyList}; +type PyMixedPauliTerm = (f64, Vec<(String, usize)>); + +fn pauli_string_terms(pauli: &pecos_core::PauliString) -> Vec<(String, usize)> { + pauli + .paulis() + .iter() + .map(|(p, q)| { + let label = match p { + Pauli::I => "I", + Pauli::X => "X", + Pauli::Y => "Y", + Pauli::Z => "Z", + }; + (label.to_string(), q.index()) + }) + .collect() +} + +fn mixed_pauli_terms(channel: &ChannelExpr) -> PyResult> { + match channel { + ChannelExpr::Unitary(unitary) => { + let pauli = unitary.clone().try_to_pauli_string().ok_or_else(|| { + pyo3::exceptions::PyValueError::new_err( + "channel unitary is not representable as a Pauli operator", + ) + })?; + Ok(vec![(1.0, pauli_string_terms(&pauli))]) + } + ChannelExpr::MixedUnitary(ops) => ops + .iter() + .map(|(prob, unitary)| { + let pauli = unitary.clone().try_to_pauli_string().ok_or_else(|| { + pyo3::exceptions::PyValueError::new_err( + "mixed-unitary channel contains a non-Pauli unitary", + ) + })?; + Ok((*prob, pauli_string_terms(&pauli))) + }) + .collect(), + _ => Err(pyo3::exceptions::PyValueError::new_err( + "channel is not a Pauli mixed-unitary channel", + )), + } +} + +fn validate_probability(name: &str, p: f64) -> PyResult<()> { + if (0.0..=1.0).contains(&p) { + Ok(()) + } else { + Err(pyo3::exceptions::PyValueError::new_err(format!( + "{name} must be in [0, 1], got {p}" + ))) + } +} + +fn receives_two_qubit_noise(gate_type: GateType) -> bool { + matches!( + gate_type, + GateType::CX + | GateType::CY + | GateType::CZ + | GateType::SZZ + | GateType::SZZdg + | GateType::SXX + | GateType::SXXdg + | GateType::SYY + | GateType::SYYdg + | GateType::SWAP + | GateType::CRZ + | GateType::RXX + | GateType::RYY + | GateType::RZZ + ) +} + /// Convert a Rust Attribute to a Python object. fn attribute_to_py(py: Python<'_>, attr: &Attribute) -> Py { match attr { @@ -634,6 +709,22 @@ impl PyGate { self.inner.is_two_qubit() } + /// Check if this gate carries a channel payload. + fn is_channel(&self) -> bool { + self.inner.is_channel() + } + + /// Return a Pauli mixed-unitary channel payload as `(probability, terms)`. + /// + /// Each term is a list of `(pauli, qubit)` pairs. Identity terms are + /// represented by an empty list. Non-Pauli channels raise `ValueError`. + fn channel_mixed_pauli_terms(&self) -> PyResult> { + let channel = self.inner.channel_expr().ok_or_else(|| { + pyo3::exceptions::PyValueError::new_err("gate does not carry a channel payload") + })?; + mixed_pauli_terms(channel) + } + // Factory methods for common gates /// Create a Hadamard gate. @@ -2458,6 +2549,106 @@ impl PyTickCircuit { self.inner.fill_idle_gates(); } + /// Return a new circuit with explicit Pauli channel operations inserted. + /// + /// This compiles gate-triggered quantum noise into inline channel gates. + /// Measurement readout noise is intentionally not represented here because + /// it is classical outcome noise, not a quantum channel after measurement. + #[pyo3(signature = (p1=0.0, p2=0.0, p_meas=0.0, p_prep=0.0))] + fn with_noise(&self, p1: f64, p2: f64, p_meas: f64, p_prep: f64) -> PyResult { + validate_probability("p1", p1)?; + validate_probability("p2", p2)?; + validate_probability("p_meas", p_meas)?; + validate_probability("p_prep", p_prep)?; + + if p_meas > 0.0 { + return Err(pyo3::exceptions::PyValueError::new_err( + "TickCircuit.with_noise inserts quantum channel operations and cannot represent classical measurement readout noise; use sim_neo(...).noise(...) for p_meas", + )); + } + + if p2 > 0.0 { + for (tick_idx, gate) in self.inner.iter_gates_with_tick() { + if receives_two_qubit_noise(gate.gate_type) && !gate.qubits.len().is_multiple_of(2) + { + return Err(pyo3::exceptions::PyValueError::new_err(format!( + "{:?} at tick {tick_idx} has {} qubits; expected pairs", + gate.gate_type, + gate.qubits.len() + ))); + } + } + } + + let noisy = self + .inner + .try_with_noise(&|gate: &Gate| -> Vec { + let mut channels = Vec::new(); + match gate.gate_type { + GateType::PZ | GateType::QAlloc if p_prep > 0.0 => { + channels.extend( + gate.qubits + .iter() + .map(|q| pecos_core::channel::BitFlip(p_prep, q.index())), + ); + } + GateType::I + | GateType::X + | GateType::Y + | GateType::Z + | GateType::H + | GateType::F + | GateType::Fdg + | GateType::SX + | GateType::SXdg + | GateType::SY + | GateType::SYdg + | GateType::SZ + | GateType::SZdg + | GateType::T + | GateType::Tdg + | GateType::RX + | GateType::RY + | GateType::RZ + | GateType::U + | GateType::R1XY + | GateType::Idle + if p1 > 0.0 => + { + channels.extend( + gate.qubits + .iter() + .map(|q| pecos_core::channel::Depolarizing(p1, q.index())), + ); + } + GateType::CX + | GateType::CY + | GateType::CZ + | GateType::SZZ + | GateType::SZZdg + | GateType::SXX + | GateType::SXXdg + | GateType::SYY + | GateType::SYYdg + | GateType::SWAP + | GateType::CRZ + | GateType::RXX + | GateType::RYY + | GateType::RZZ + if p2 > 0.0 => + { + channels.extend(gate.qubits.chunks_exact(2).map(|pair| { + pecos_core::channel::Depolarizing2(p2, pair[0].index(), pair[1].index()) + })); + } + _ => {} + } + channels + }) + .map_err(pyo3::exceptions::PyValueError::new_err)?; + Ok(Self { inner: noisy }) + } + /// Compact ticks by merging gates into earlier ticks when possible. /// /// ASAP scheduling: gates that don't share qubits are merged into the diff --git a/python/quantum-pecos/tests/qec/test_inline_channel_sim_neo.py b/python/quantum-pecos/tests/qec/test_inline_channel_sim_neo.py new file mode 100644 index 000000000..69555febb --- /dev/null +++ b/python/quantum-pecos/tests/qec/test_inline_channel_sim_neo.py @@ -0,0 +1,74 @@ +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 + +"""Inline TickCircuit channel tests for sim_neo Python bindings.""" + +import pytest +from pecos_rslib.quantum import TickCircuit +from pecos_rslib_exp import depolarizing, meas_sampling, sim_neo, stabilizer + + +def prep_measure_circuit() -> TickCircuit: + tc = TickCircuit() + tc.tick().pz([0]) + tc.tick().mz([0]) + return tc + + +def measurement_rows(result) -> list[list[int]]: + return [list(row) for row in result.to_list()] + + +def test_tick_circuit_with_noise_inserts_channel_payload() -> None: + noisy = prep_measure_circuit().with_noise(p_prep=1.0) + channel_gates = [gate for _, gate in noisy.gates() if gate.is_channel()] + + assert len(channel_gates) == 1 + assert channel_gates[0].channel_mixed_pauli_terms() == [ + (0.0, []), + (1.0, [("X", 0)]), + ] + + +def test_tick_circuit_with_noise_rejects_measurement_readout_noise() -> None: + with pytest.raises(ValueError, match="measurement readout noise"): + prep_measure_circuit().with_noise(p_meas=0.1) + + +def test_tick_circuit_with_noise_rejects_invalid_probabilities() -> None: + with pytest.raises(ValueError, match="p1 must be in \\[0, 1\\]"): + prep_measure_circuit().with_noise(p1=-0.1) + + with pytest.raises(ValueError, match="p2 must be in \\[0, 1\\]"): + prep_measure_circuit().with_noise(p2=1.1) + + +def test_sim_neo_default_routes_inline_channels_through_density_matrix() -> None: + noisy = prep_measure_circuit().with_noise(p_prep=1.0) + + result = sim_neo(noisy).shots(5).seed(123).run() + + assert measurement_rows(result) == [[1], [1], [1], [1], [1]] + + +def test_sim_neo_stabilizer_samples_inline_pauli_channels() -> None: + noisy = prep_measure_circuit().with_noise(p_prep=1.0) + + result = sim_neo(noisy).quantum(stabilizer()).shots(5).seed(123).run() + + assert measurement_rows(result) == [[1], [1], [1], [1], [1]] + + +def test_sim_neo_rejects_noise_builder_with_inline_channels() -> None: + noisy = prep_measure_circuit().with_noise(p_prep=1.0) + noise = depolarizing().p1(0.1) + + with pytest.raises(ValueError, match="do not also pass"): + sim_neo(noisy).noise(noise).run() + + +def test_sim_neo_meas_sampling_rejects_inline_channels() -> None: + noisy = prep_measure_circuit().with_noise(p_prep=1.0) + + with pytest.raises(ValueError, match="does not consume inline channel"): + sim_neo(noisy).quantum(meas_sampling()).run() From 6f4adc32546ffef1742b8ef19e44d8d2c8680e45 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 13:58:46 -0600 Subject: [PATCH 089/125] Add tomography helpers and catalog propagation reuse --- .../src/fault_tolerance/fault_sampler.rs | 124 +++++++- crates/pecos-quantum/src/channel.rs | 294 ++++++++++++++++++ crates/pecos-quantum/src/diamond_norm.rs | 145 +++++++++ crates/pecos-quantum/src/lib.rs | 19 +- docs/user-guide/quantum-info.md | 24 ++ .../pecos-rslib/src/quantum_info_bindings.rs | 124 +++++++- .../quantum-pecos/src/pecos/quantum_info.py | 4 + .../tests/pecos/test_quantum_info_bindings.py | 30 ++ 8 files changed, 744 insertions(+), 20 deletions(-) diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index 8525b2f3c..0944b41da 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -169,7 +169,7 @@ pub(crate) struct GateLoc { } /// Single-qubit Pauli type for fault injection. -#[derive(Clone, Copy, Debug, PartialEq, Eq)] +#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)] pub(crate) enum PauliType { X, Y, @@ -349,6 +349,7 @@ fn propagate_single_effect( } } +#[cfg(test)] fn propagate_pair_effect( faults: [(PauliType, usize); 2], start: usize, @@ -373,11 +374,81 @@ fn propagate_pair_effect( } } +#[derive(Clone, Debug, PartialEq, Eq)] struct PropagatedFaultEffect { affected_measurements: BTreeSet, affected_tracked_ops: Vec, } +#[derive(Default)] +struct PropagatedEffectCache { + singles: HashMap<(usize, PauliType, usize), PropagatedFaultEffect>, +} + +impl PropagatedEffectCache { + fn single( + &mut self, + pauli: PauliType, + qubit: usize, + start: usize, + gates: &[GateLoc], + meas_positions: &HashMap, + tracked_ops: &[PauliString], + ) -> PropagatedFaultEffect { + self.singles + .entry((start, pauli, qubit)) + .or_insert_with(|| { + propagate_single_effect(pauli, qubit, start, gates, meas_positions, tracked_ops) + }) + .clone() + } +} + +fn xor_fault_effects( + left: &PropagatedFaultEffect, + right: &PropagatedFaultEffect, +) -> PropagatedFaultEffect { + let mut affected_measurements = left.affected_measurements.clone(); + for &measurement in &right.affected_measurements { + if !affected_measurements.remove(&measurement) { + affected_measurements.insert(measurement); + } + } + + PropagatedFaultEffect { + affected_measurements, + affected_tracked_ops: xor_sorted_unique_indices( + &left.affected_tracked_ops, + &right.affected_tracked_ops, + ), + } +} + +fn xor_sorted_unique_indices(left: &[usize], right: &[usize]) -> Vec { + let mut out = Vec::with_capacity(left.len() + right.len()); + let mut i = 0usize; + let mut j = 0usize; + while i < left.len() && j < right.len() { + match left[i].cmp(&right[j]) { + std::cmp::Ordering::Less => { + out.push(left[i]); + i += 1; + } + std::cmp::Ordering::Greater => { + out.push(right[j]); + j += 1; + } + std::cmp::Ordering::Equal => { + i += 1; + j += 1; + } + } + } + out.extend_from_slice(&left[i..]); + out.extend_from_slice(&right[j..]); + out +} + /// Core forward propagation: evolve a Pauli through gates, collecting affected measurements. fn propagate_forward( prop: &mut BitmaskPauliProp, @@ -1041,6 +1112,7 @@ fn build_structural_fault_catalog(tc: &TickCircuit) -> Result Result Result Result Result Result { let q = loc.qubits[0]; - let effect = propagate_single_effect( + let effect = effect_cache.single( PauliType::X, q, loc_idx + 1, @@ -2135,6 +2217,34 @@ mod tests { ); } + #[test] + fn test_xor_combined_single_effects_match_pair_propagation() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().h(&[QubitId(1)]); + tc.tick().mz(&[QubitId(0), QubitId(1)]); + tc.tracked_operator_labeled("tracked_z0", PauliString::z(0)); + tc.tracked_operator_labeled("tracked_z1", PauliString::z(1)); + + let (gates, meas_pos) = flatten_tick_circuit(&tc); + let tracked_ops = parse_tracked_operator_annotations(&tc); + let start = 1; + let left = propagate_single_effect(PauliType::X, 0, start, &gates, &meas_pos, &tracked_ops); + let right = + propagate_single_effect(PauliType::Z, 1, start, &gates, &meas_pos, &tracked_ops); + let combined = xor_fault_effects(&left, &right); + let direct = propagate_pair_effect( + [(PauliType::X, 0), (PauliType::Z, 1)], + start, + &gates, + &meas_pos, + &tracked_ops, + ); + + assert_eq!(combined, direct); + } + #[test] fn test_propagate_x_check_round_reaches_ancilla_only() { // X-check pattern: H(0) CX(0,1) CX(0,2) H(0) MZ(0) diff --git a/crates/pecos-quantum/src/channel.rs b/crates/pecos-quantum/src/channel.rs index 81b07dadf..ebecb3139 100644 --- a/crates/pecos-quantum/src/channel.rs +++ b/crates/pecos-quantum/src/channel.rs @@ -89,6 +89,13 @@ pub enum ChannelError { /// Highest qubit touched by the offending Pauli term. qubit: usize, }, + /// Two channel objects act on different numbers of qubits. + QubitCountMismatch { + /// Expected qubit count. + expected: usize, + /// Actual qubit count. + actual: usize, + }, /// A coefficient or fidelity is not finite. InvalidCoefficient { /// Offending coefficient. @@ -151,6 +158,22 @@ pub enum ChannelError { /// Actual number of supplied outputs. actual: usize, }, + /// A tomography input index is outside the experiment design. + TomographyInputOutOfRange { + /// Number of tomography inputs in the design. + num_inputs: usize, + /// Invalid input index. + index: usize, + }, + /// A computational matrix-unit row/column is outside the Hilbert space. + MatrixUnitOutOfRange { + /// Hilbert-space dimension. + dim: usize, + /// Invalid row. + row: usize, + /// Invalid column. + col: usize, + }, } impl fmt::Display for ChannelError { @@ -173,6 +196,10 @@ impl fmt::Display for ChannelError { f, "Pauli term touches qubit {qubit}, outside declared {num_qubits}-qubit range" ), + Self::QubitCountMismatch { expected, actual } => write!( + f, + "channel qubit count mismatch: expected {expected}, got {actual}" + ), Self::InvalidCoefficient { value } => { write!(f, "invalid non-finite coefficient: {value}") } @@ -211,6 +238,14 @@ impl fmt::Display for ChannelError { f, "invalid tomography sample count {actual}; expected {expected} operator-basis outputs" ), + Self::TomographyInputOutOfRange { num_inputs, index } => write!( + f, + "tomography input index {index} is outside the {num_inputs}-input design" + ), + Self::MatrixUnitOutOfRange { dim, row, col } => write!( + f, + "matrix unit |{row}><{col}| is outside the {dim}-dimensional Hilbert space" + ), } } } @@ -2375,6 +2410,176 @@ pub fn matrix_unit_basis(num_qubits: usize) -> Result>, C Ok(basis) } +/// Metadata for one computational matrix-unit tomography input. +/// +/// The input operator is `|row> Result { + let dim = hilbert_dim(num_qubits)?; + let num_inputs = pauli_basis_len(num_qubits)?; + Ok(Self { + num_qubits, + dim, + num_inputs, + }) + } + + /// Returns the number of qubits in the characterized channel. + #[must_use] + pub const fn num_qubits(&self) -> usize { + self.num_qubits + } + + /// Returns the Hilbert-space dimension `2^num_qubits`. + #[must_use] + pub const fn dim(&self) -> usize { + self.dim + } + + /// Returns the number of matrix-unit input operators, `dim^2`. + #[must_use] + pub const fn num_inputs(&self) -> usize { + self.num_inputs + } + + /// Returns the index for matrix unit `|row> Result { + if row >= self.dim || col >= self.dim { + return Err(ChannelError::MatrixUnitOutOfRange { + dim: self.dim, + row, + col, + }); + } + Ok(matrix_unit_index(self.dim, row, col)) + } + + /// Returns metadata for one matrix-unit input. + /// + /// # Errors + /// + /// Returns an error if `index` is outside the design. + pub fn input_metadata(&self, index: usize) -> Result { + if index >= self.num_inputs { + return Err(ChannelError::TomographyInputOutOfRange { + num_inputs: self.num_inputs, + index, + }); + } + Ok(MatrixUnitTomographyInput { + index, + row: index % self.dim, + col: index / self.dim, + }) + } + + /// Returns metadata for all matrix-unit inputs in reconstruction order. + #[must_use] + pub fn input_metadata_all(&self) -> Vec { + (0..self.num_inputs) + .map(|index| MatrixUnitTomographyInput { + index, + row: index % self.dim, + col: index / self.dim, + }) + .collect() + } + + /// Returns the matrix-unit input operator at `index`. + /// + /// # Errors + /// + /// Returns an error if `index` is outside the design. + pub fn input_operator(&self, index: usize) -> Result, ChannelError> { + let input = self.input_metadata(index)?; + let mut matrix = DMatrix::zeros(self.dim, self.dim); + matrix[(input.row, input.col)] = Complex64::new(1.0, 0.0); + Ok(matrix) + } + + /// Returns all matrix-unit input operators in reconstruction order. + #[must_use] + pub fn input_operators(&self) -> Vec> { + (0..self.num_inputs) + .map(|index| { + let row = index % self.dim; + let col = index / self.dim; + let mut matrix = DMatrix::zeros(self.dim, self.dim); + matrix[(row, col)] = Complex64::new(1.0, 0.0); + matrix + }) + .collect() + } + + /// Applies `channel` to each design input in reconstruction order. + /// + /// # Errors + /// + /// Returns an error when `channel` acts on a different number of qubits or + /// if channel application fails. + pub fn simulate_outputs( + &self, + channel: &ChoiMatrix, + ) -> Result>, ChannelError> { + if channel.num_qubits() != self.num_qubits { + return Err(ChannelError::QubitCountMismatch { + expected: self.num_qubits, + actual: channel.num_qubits(), + }); + } + self.input_operators() + .iter() + .map(|operator| channel.apply_to_operator(operator)) + .collect() + } + + /// Reconstructs a Choi matrix from outputs ordered by this design. + /// + /// # Errors + /// + /// Returns an error when output count or shapes do not match the design. + pub fn reconstruct_choi( + &self, + outputs: &[DMatrix], + ) -> Result { + ChoiMatrix::from_matrix_unit_outputs(self.num_qubits, outputs) + } +} + /// Samples a Hilbert-Schmidt random density matrix on `num_qubits` qubits. /// /// This samples a square complex Ginibre matrix `G` and returns @@ -3680,6 +3885,95 @@ mod tests { } } + #[test] + fn process_tomography_design_exposes_matrix_unit_order() { + let design = ProcessTomographyDesign::matrix_unit(1).unwrap(); + assert_eq!(design.num_qubits(), 1); + assert_eq!(design.dim(), 2); + assert_eq!(design.num_inputs(), 4); + assert_eq!(design.input_index(0, 0).unwrap(), 0); + assert_eq!(design.input_index(1, 0).unwrap(), 1); + assert_eq!(design.input_index(0, 1).unwrap(), 2); + assert_eq!(design.input_index(1, 1).unwrap(), 3); + + let metadata = design.input_metadata_all(); + assert_eq!( + metadata, + vec![ + MatrixUnitTomographyInput { + index: 0, + row: 0, + col: 0 + }, + MatrixUnitTomographyInput { + index: 1, + row: 1, + col: 0 + }, + MatrixUnitTomographyInput { + index: 2, + row: 0, + col: 1 + }, + MatrixUnitTomographyInput { + index: 3, + row: 1, + col: 1 + }, + ] + ); + + let from_design = design.input_operators(); + let from_free_function = matrix_unit_basis(1).unwrap(); + for (actual, expected) in from_design.iter().zip(from_free_function.iter()) { + assert_complex_matrix_close(actual, expected); + } + } + + #[test] + fn process_tomography_design_reconstructs_channel_outputs() { + let Op::Channel(expr) = op::AmplitudeDamping(0.25, 0) else { + panic!("expected channel"); + }; + let expected = ChoiMatrix::from_channel_expr(&expr).unwrap(); + let design = ProcessTomographyDesign::matrix_unit(1).unwrap(); + let outputs = design.simulate_outputs(&expected).unwrap(); + let reconstructed = design.reconstruct_choi(&outputs).unwrap(); + + assert_complex_matrix_close(reconstructed.matrix(), expected.matrix()); + assert!(reconstructed.is_cptp()); + assert!(!reconstructed.is_unital()); + } + + #[test] + fn process_tomography_design_rejects_invalid_inputs() { + let design = ProcessTomographyDesign::matrix_unit(1).unwrap(); + assert!(matches!( + design.input_metadata(4).unwrap_err(), + ChannelError::TomographyInputOutOfRange { + num_inputs: 4, + index: 4 + } + )); + assert!(matches!( + design.input_index(2, 0).unwrap_err(), + ChannelError::MatrixUnitOutOfRange { + dim: 2, + row: 2, + col: 0 + } + )); + + let two_qubit_channel = ChoiMatrix::from_unitary(&unitary::I(0), 2).unwrap(); + assert!(matches!( + design.simulate_outputs(&two_qubit_channel).unwrap_err(), + ChannelError::QubitCountMismatch { + expected: 1, + actual: 2 + } + )); + } + #[test] fn choi_reconstructs_identity_from_matrix_unit_outputs() { let inputs = matrix_unit_basis(1).unwrap(); diff --git a/crates/pecos-quantum/src/diamond_norm.rs b/crates/pecos-quantum/src/diamond_norm.rs index 87d4c4593..34ea27c22 100644 --- a/crates/pecos-quantum/src/diamond_norm.rs +++ b/crates/pecos-quantum/src/diamond_norm.rs @@ -52,6 +52,24 @@ pub enum DiamondNormError { /// Allowed tolerance. tolerance: f64, }, + /// A Choi matrix does not match the expected input/output dimensions. + InvalidChoiShape { + /// Expected row count. + expected_rows: usize, + /// Expected column count. + expected_cols: usize, + /// Actual row count. + rows: usize, + /// Actual column count. + cols: usize, + }, + /// Input/output dimensions overflowed a `usize` matrix dimension. + DimensionOverflow { + /// Input Hilbert-space dimension. + dim_in: usize, + /// Output Hilbert-space dimension. + dim_out: usize, + }, /// A matrix entry was not finite. NonFiniteEntry, /// Two channel representations act on different Hilbert spaces. @@ -85,6 +103,19 @@ impl fmt::Display for DiamondNormError { f, "matrix is not Hermitian/symmetric within tolerance {tolerance}; max difference {max_difference}" ), + Self::InvalidChoiShape { + expected_rows, + expected_cols, + rows, + cols, + } => write!( + f, + "invalid Choi matrix shape {rows}x{cols}; expected {expected_rows}x{expected_cols}" + ), + Self::DimensionOverflow { dim_in, dim_out } => write!( + f, + "Choi input/output dimensions overflow usize: dim_in={dim_in}, dim_out={dim_out}" + ), Self::NonFiniteEntry => write!(f, "matrix contains a non-finite entry"), Self::QubitCountMismatch { left, right } => write!( f, @@ -274,6 +305,64 @@ pub fn hermitian_to_real_symmetric_with_tolerance( Ok(out) } +/// Converts PECOS's column-stacked Choi convention to the transposed +/// row-vector convention used by the Watrous diamond-norm SDP objective. +/// +/// PECOS indexes Choi rows and columns as `output + input * dim_output`. +/// This helper performs the same convention transform described in Qiskit's +/// diamond-norm implementation: +/// +/// ```text +/// reshape(J, (dim_in, dim_out, dim_in, dim_out)) +/// transpose axes (3, 2, 1, 0) +/// reshape back to a matrix +/// ``` +/// +/// The result is not a public diamond-norm implementation. It is a tested +/// convention helper for the future PECOS-owned SDP assembly. +/// +/// # Errors +/// +/// Returns an error if `choi` is not `(dim_in * dim_out) x (dim_in * dim_out)` +/// or if it contains a non-finite entry. +pub fn choi_to_watrous_row_transpose( + choi: &DMatrix, + dim_in: usize, + dim_out: usize, +) -> Result, DiamondNormError> { + let size = dim_in + .checked_mul(dim_out) + .ok_or(DiamondNormError::DimensionOverflow { dim_in, dim_out })?; + if choi.nrows() != size || choi.ncols() != size { + return Err(DiamondNormError::InvalidChoiShape { + expected_rows: size, + expected_cols: size, + rows: choi.nrows(), + cols: choi.ncols(), + }); + } + + let mut out = DMatrix::zeros(size, size); + for input_row in 0..dim_in { + for output_row in 0..dim_out { + let src_row = output_row + input_row * dim_out; + for input_col in 0..dim_in { + for output_col in 0..dim_out { + let src_col = output_col + input_col * dim_out; + let value = choi[(src_row, src_col)]; + if !value.re.is_finite() || !value.im.is_finite() { + return Err(DiamondNormError::NonFiniteEntry); + } + let dst_row = input_col + output_col * dim_in; + let dst_col = input_row + output_row * dim_in; + out[(dst_row, dst_col)] = value; + } + } + } + } + Ok(out) +} + fn validate_real_symmetric(matrix: &DMatrix, tolerance: f64) -> Result<(), DiamondNormError> { if matrix.nrows() != matrix.ncols() { return Err(DiamondNormError::NonSquareMatrix { @@ -420,6 +509,57 @@ mod tests { assert_close(embedded.trace(), 10.0); } + #[test] + fn choi_to_watrous_row_transpose_matches_reference_axis_permutation() { + let choi = DMatrix::from_row_slice( + 4, + 4, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(2.0, 0.0), + Complex64::new(3.0, 0.0), + Complex64::new(4.0, 0.0), + Complex64::new(5.0, 0.0), + Complex64::new(6.0, 0.0), + Complex64::new(7.0, 0.0), + Complex64::new(8.0, 0.0), + Complex64::new(9.0, 0.0), + Complex64::new(10.0, 0.0), + Complex64::new(11.0, 0.0), + Complex64::new(12.0, 0.0), + Complex64::new(13.0, 0.0), + Complex64::new(14.0, 0.0), + Complex64::new(15.0, 0.0), + ], + ); + let converted = choi_to_watrous_row_transpose(&choi, 2, 2).unwrap(); + let expected = DMatrix::from_row_slice( + 4, + 4, + &[ + Complex64::new(0.0, 0.0), + Complex64::new(8.0, 0.0), + Complex64::new(4.0, 0.0), + Complex64::new(12.0, 0.0), + Complex64::new(2.0, 0.0), + Complex64::new(10.0, 0.0), + Complex64::new(6.0, 0.0), + Complex64::new(14.0, 0.0), + Complex64::new(1.0, 0.0), + Complex64::new(9.0, 0.0), + Complex64::new(5.0, 0.0), + Complex64::new(13.0, 0.0), + Complex64::new(3.0, 0.0), + Complex64::new(11.0, 0.0), + Complex64::new(7.0, 0.0), + Complex64::new(15.0, 0.0), + ], + ); + + assert_eq!(converted, expected); + } + #[test] fn helper_validation_rejects_invalid_inputs() { assert!(matches!( @@ -452,5 +592,10 @@ mod tests { hermitian_to_real_symmetric(&nonhermitian).unwrap_err(), DiamondNormError::NonHermitian { .. } )); + + assert!(matches!( + choi_to_watrous_row_transpose(&DMatrix::zeros(2, 2), 2, 2).unwrap_err(), + DiamondNormError::InvalidChoiShape { .. } + )); } } diff --git a/crates/pecos-quantum/src/lib.rs b/crates/pecos-quantum/src/lib.rs index 3ec7bb8a7..0e8123d16 100644 --- a/crates/pecos-quantum/src/lib.rs +++ b/crates/pecos-quantum/src/lib.rs @@ -102,17 +102,18 @@ pub use pecos_num::dag::DagWouldCycleError; // Concrete channel representation types pub use channel::{ - ChannelError, ChiMatrix, ChoiMatrix, DiagonalPtm, KrausOps, PauliChannel, PauliSum, Ptm, - PtmBasisOrder, Stinespring, SuperOp, basis_bitmask, basis_digit_to_pauli, basis_element, - basis_index, basis_label, bitmask_label, matrix_unit_basis, partial_trace, pauli_basis_len, - pauli_string_to_bitmask, pauli_to_basis_digit, random_1q_clifford, random_2q_clifford, - random_clifford, random_density_matrix, random_density_matrix_with_rank, random_pauli, - random_quantum_channel, + ChannelError, ChiMatrix, ChoiMatrix, DiagonalPtm, KrausOps, MatrixUnitTomographyInput, + PauliChannel, PauliSum, ProcessTomographyDesign, Ptm, PtmBasisOrder, Stinespring, SuperOp, + basis_bitmask, basis_digit_to_pauli, basis_element, basis_index, basis_label, bitmask_label, + matrix_unit_basis, partial_trace, pauli_basis_len, pauli_string_to_bitmask, + pauli_to_basis_digit, random_1q_clifford, random_2q_clifford, random_clifford, + random_density_matrix, random_density_matrix_with_rank, random_pauli, random_quantum_channel, }; pub use diamond_norm::{ - DiamondNormError, hermitian_to_real_symmetric, hermitian_to_real_symmetric_with_tolerance, - pauli_channel_diamond_distance, pauli_channel_diamond_norm, scaled_psd_triangle_len, - smat_real_symmetric, svec_real_symmetric, svec_real_symmetric_with_tolerance, + DiamondNormError, choi_to_watrous_row_transpose, hermitian_to_real_symmetric, + hermitian_to_real_symmetric_with_tolerance, pauli_channel_diamond_distance, + pauli_channel_diamond_norm, scaled_psd_triangle_len, smat_real_symmetric, svec_real_symmetric, + svec_real_symmetric_with_tolerance, }; pub use measures::{ DensityMatrixPartialTrace, MeasureError, SchmidtTerm, average_gate_fidelity, concurrence, diff --git a/docs/user-guide/quantum-info.md b/docs/user-guide/quantum-info.md index 688770308..6dd236c9b 100644 --- a/docs/user-guide/quantum-info.md +++ b/docs/user-guide/quantum-info.md @@ -90,6 +90,30 @@ trace_check = choi.partial_trace_output() For PECOS's Choi convention, a trace-preserving channel satisfies `partial_trace_output() == I`. +## Process Tomography Helpers + +`ProcessTomographyDesign.matrix_unit(n)` gives the complete computational +matrix-unit operator basis used by PECOS Choi reconstruction. This is a +linear-inversion design for exact channel characterization and simulator +validation; it is not a physical state-preparation recipe. + +```python +from pecos.quantum_info import ProcessTomographyDesign, Ptm + +design = ProcessTomographyDesign.matrix_unit(1) +assert design.input_metadata_all() == [ + (0, 0, 0), # |0><0| + (1, 1, 0), # |1><0| + (2, 0, 1), # |0><1| + (3, 1, 1), # |1><1| +] + +choi = Ptm.identity(1).to_choi() +outputs = design.simulate_outputs(choi) +reconstructed = design.reconstruct_choi(outputs) +assert reconstructed.matrix() == choi.matrix() +``` + The dense channel forms convert through the same Rust-backed validation path: ```python diff --git a/python/pecos-rslib/src/quantum_info_bindings.rs b/python/pecos-rslib/src/quantum_info_bindings.rs index a4c34dc79..de5eb58b1 100644 --- a/python/pecos-rslib/src/quantum_info_bindings.rs +++ b/python/pecos-rslib/src/quantum_info_bindings.rs @@ -19,10 +19,11 @@ use num_complex::Complex64; use pecos_core::PauliBitmaskSmall; use pecos_quantum::{ ChiMatrix as RustChiMatrix, ChoiMatrix as RustChoiMatrix, KrausOps as RustKrausOps, - PauliChannel as RustPauliChannel, Ptm as RustPtm, Stinespring as RustStinespring, - SuperOp as RustSuperOp, average_gate_fidelity as rust_average_gate_fidelity, - entropy as rust_entropy, gate_error as rust_gate_error, - hellinger_distance as rust_hellinger_distance, hellinger_fidelity as rust_hellinger_fidelity, + PauliChannel as RustPauliChannel, ProcessTomographyDesign as RustProcessTomographyDesign, + Ptm as RustPtm, Stinespring as RustStinespring, SuperOp as RustSuperOp, + average_gate_fidelity as rust_average_gate_fidelity, entropy as rust_entropy, + gate_error as rust_gate_error, hellinger_distance as rust_hellinger_distance, + hellinger_fidelity as rust_hellinger_fidelity, logarithmic_negativity as rust_logarithmic_negativity, negativity as rust_negativity, pauli_basis_len, process_fidelity as rust_process_fidelity, purity as rust_purity, random_density_matrix as rust_random_density_matrix, @@ -63,6 +64,12 @@ fn complex_matrix_from_rows(rows: Vec>) -> PyResult>>, +) -> PyResult>> { + matrices.into_iter().map(complex_matrix_from_rows).collect() +} + fn real_matrix_to_rows(matrix: &DMatrix) -> Vec> { (0..matrix.nrows()) .map(|row| (0..matrix.ncols()).map(|col| matrix[(row, col)]).collect()) @@ -75,6 +82,10 @@ fn complex_matrix_to_rows(matrix: &DMatrix) -> Vec> { .collect() } +fn complex_matrices_to_rows(matrices: &[DMatrix]) -> Vec>> { + matrices.iter().map(complex_matrix_to_rows).collect() +} + fn parse_pauli_label(num_qubits: usize, label: &str) -> PyResult { let label = label.trim(); if label.len() != num_qubits { @@ -327,6 +338,20 @@ impl PyChoiMatrix { }) } + #[staticmethod] + fn from_matrix_unit_outputs( + num_qubits: usize, + outputs: Vec>>, + ) -> PyResult { + Ok(Self { + inner: RustChoiMatrix::from_matrix_unit_outputs( + num_qubits, + &complex_matrices_from_rows(outputs)?, + ) + .map_err(py_value_err)?, + }) + } + fn num_qubits(&self) -> usize { self.inner.num_qubits() } @@ -401,6 +426,86 @@ impl PyChoiMatrix { } } +#[pyclass(name = "ProcessTomographyDesign", module = "pecos_rslib.quantum_info")] +pub struct PyProcessTomographyDesign { + inner: RustProcessTomographyDesign, +} + +#[pymethods] +impl PyProcessTomographyDesign { + #[staticmethod] + fn matrix_unit(num_qubits: usize) -> PyResult { + Ok(Self { + inner: RustProcessTomographyDesign::matrix_unit(num_qubits).map_err(py_value_err)?, + }) + } + + fn num_qubits(&self) -> usize { + self.inner.num_qubits() + } + + fn dim(&self) -> usize { + self.inner.dim() + } + + fn num_inputs(&self) -> usize { + self.inner.num_inputs() + } + + fn input_index(&self, row: usize, col: usize) -> PyResult { + self.inner.input_index(row, col).map_err(py_value_err) + } + + fn input_metadata(&self, index: usize) -> PyResult<(usize, usize, usize)> { + let input = self.inner.input_metadata(index).map_err(py_value_err)?; + Ok((input.index, input.row, input.col)) + } + + fn input_metadata_all(&self) -> Vec<(usize, usize, usize)> { + self.inner + .input_metadata_all() + .into_iter() + .map(|input| (input.index, input.row, input.col)) + .collect() + } + + fn input_operator(&self, index: usize) -> PyResult>> { + Ok(complex_matrix_to_rows( + &self.inner.input_operator(index).map_err(py_value_err)?, + )) + } + + fn input_operators(&self) -> Vec>> { + complex_matrices_to_rows(&self.inner.input_operators()) + } + + fn simulate_outputs(&self, channel: &PyChoiMatrix) -> PyResult>>> { + Ok(complex_matrices_to_rows( + &self + .inner + .simulate_outputs(&channel.inner) + .map_err(py_value_err)?, + )) + } + + fn reconstruct_choi(&self, outputs: Vec>>) -> PyResult { + Ok(PyChoiMatrix { + inner: self + .inner + .reconstruct_choi(&complex_matrices_from_rows(outputs)?) + .map_err(py_value_err)?, + }) + } + + fn __repr__(&self) -> String { + format!( + "ProcessTomographyDesign(num_qubits={}, num_inputs={})", + self.inner.num_qubits(), + self.inner.num_inputs() + ) + } +} + #[pyclass(name = "SuperOp", module = "pecos_rslib.quantum_info")] pub struct PySuperOp { inner: RustSuperOp, @@ -645,6 +750,13 @@ fn pauli_channel_diamond_distance(left: &PyPauliChannel, right: &PyPauliChannel) pecos_quantum::pauli_channel_diamond_distance(&left.inner, &right.inner).map_err(py_value_err) } +#[pyfunction] +fn matrix_unit_basis(num_qubits: usize) -> PyResult>>> { + Ok(complex_matrices_to_rows( + &pecos_quantum::matrix_unit_basis(num_qubits).map_err(py_value_err)?, + )) +} + #[pyfunction] fn random_density_matrix(num_qubits: usize, seed: u64) -> PyResult>> { let mut rng = PecosRng::seed_from_u64(seed); @@ -667,6 +779,7 @@ pub fn register_quantum_info_module(parent: &Bound<'_, PyModule>) -> PyResult<() parent.add_class::()?; parent.add_class::()?; parent.add_class::()?; + parent.add_class::()?; parent.add_class::()?; parent.add_class::()?; parent.add_class::()?; @@ -689,6 +802,7 @@ pub fn register_quantum_info_module(parent: &Bound<'_, PyModule>) -> PyResult<() parent.add_function(wrap_pyfunction!(gate_error, parent)?)?; parent.add_function(wrap_pyfunction!(pauli_channel_diamond_norm, parent)?)?; parent.add_function(wrap_pyfunction!(pauli_channel_diamond_distance, parent)?)?; + parent.add_function(wrap_pyfunction!(matrix_unit_basis, parent)?)?; parent.add_function(wrap_pyfunction!(random_density_matrix, parent)?)?; parent.add_function(wrap_pyfunction!(random_quantum_channel, parent)?)?; @@ -699,6 +813,7 @@ pub fn register_quantum_info_module(parent: &Bound<'_, PyModule>) -> PyResult<() "Ptm", "KrausOps", "ChoiMatrix", + "ProcessTomographyDesign", "SuperOp", "ChiMatrix", "Stinespring", @@ -717,6 +832,7 @@ pub fn register_quantum_info_module(parent: &Bound<'_, PyModule>) -> PyResult<() "gate_error", "pauli_channel_diamond_norm", "pauli_channel_diamond_distance", + "matrix_unit_basis", "random_density_matrix", "random_quantum_channel", ] { diff --git a/python/quantum-pecos/src/pecos/quantum_info.py b/python/quantum-pecos/src/pecos/quantum_info.py index dbdb30f05..e20710811 100644 --- a/python/quantum-pecos/src/pecos/quantum_info.py +++ b/python/quantum-pecos/src/pecos/quantum_info.py @@ -12,6 +12,7 @@ ChoiMatrix, KrausOps, PauliChannel, + ProcessTomographyDesign, Ptm, Stinespring, SuperOp, @@ -21,6 +22,7 @@ hellinger_distance, hellinger_fidelity, logarithmic_negativity, + matrix_unit_basis, negativity, pauli_channel_diamond_distance, pauli_channel_diamond_norm, @@ -39,6 +41,7 @@ "ChoiMatrix", "KrausOps", "PauliChannel", + "ProcessTomographyDesign", "Ptm", "Stinespring", "SuperOp", @@ -48,6 +51,7 @@ "hellinger_distance", "hellinger_fidelity", "logarithmic_negativity", + "matrix_unit_basis", "negativity", "pauli_channel_diamond_distance", "pauli_channel_diamond_norm", diff --git a/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py b/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py index d50c27116..9f22a7489 100644 --- a/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py +++ b/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py @@ -4,6 +4,7 @@ ChiMatrix, ChoiMatrix, PauliChannel, + ProcessTomographyDesign, Ptm, Stinespring, SuperOp, @@ -13,6 +14,7 @@ hellinger_distance, hellinger_fidelity, logarithmic_negativity, + matrix_unit_basis, negativity, pauli_channel_diamond_distance, pauli_channel_diamond_norm, @@ -90,6 +92,34 @@ def test_choi_and_kraus_wrappers_round_trip_identity_channel() -> None: assert_close(process_fidelity(stinespring.to_kraus().to_ptm(), identity), 1.0) +def test_process_tomography_design_reconstructs_identity_channel() -> None: + design = ProcessTomographyDesign.matrix_unit(1) + + assert design.num_qubits() == 1 + assert design.dim() == 2 + assert design.num_inputs() == 4 + assert design.input_metadata_all() == [(0, 0, 0), (1, 1, 0), (2, 0, 1), (3, 1, 1)] + assert design.input_index(1, 0) == 1 + assert_matrix_close( + design.input_operator(2), + [[0.0 + 0.0j, 1.0 + 0.0j], [0.0 + 0.0j, 0.0 + 0.0j]], + ) + assert design.input_operators() == matrix_unit_basis(1) + + choi = Ptm.identity(1).to_choi() + outputs = design.simulate_outputs(choi) + reconstructed = design.reconstruct_choi(outputs) + assert_matrix_close(reconstructed.matrix(), choi.matrix()) + assert reconstructed.is_cptp() + assert reconstructed.is_unital() + + +def test_choi_from_matrix_unit_outputs_static_constructor() -> None: + outputs = matrix_unit_basis(1) + reconstructed = ChoiMatrix.from_matrix_unit_outputs(1, outputs) + assert_matrix_close(reconstructed.matrix(), Ptm.identity(1).to_choi().matrix()) + + def test_state_measure_wrappers() -> None: zero = [1.0 + 0.0j, 0.0 + 0.0j] plus = [2.0**-0.5 + 0.0j, 2.0**-0.5 + 0.0j] From 215651db125b252d9a08ba05cd69700bd80fa41d Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 14:29:09 -0600 Subject: [PATCH 090/125] Refresh catalog benchmark plans --- crates/benchmarks/README.md | 23 ++++ .../benches/modules/fault_catalog.rs | 44 ++++++- .../src/fault_tolerance/fault_sampler.rs | 111 ++++++++++-------- crates/pecos-quantum/src/diamond_norm.rs | 4 +- docs/user-guide/quantum-info.md | 13 ++ 5 files changed, 143 insertions(+), 52 deletions(-) diff --git a/crates/benchmarks/README.md b/crates/benchmarks/README.md index 7424d17bc..52c525056 100644 --- a/crates/benchmarks/README.md +++ b/crates/benchmarks/README.md @@ -22,3 +22,26 @@ Alternatively, run manually with: ```bash RUSTFLAGS="-C target-cpu=native" cargo bench -p benchmarks ``` + +## Fault Catalog Benchmarks + +The fault-catalog suite covers rotated surface-code memory circuits at +distances 3, 5, 7, 9, and 11. It measures structural catalog construction, +noise re-parameterization, raw-mechanism materialization, and noise-sweep +strategies. + +```bash +# Full fault-catalog suite +just bench native "" "fault_catalog/" + +# Structural construction only +just bench native "" "fault_catalog/from_circuit" + +# Compare direct rebuild, cloned parameterization, and mutable with_noise sweeps +just bench native "" "fault_catalog/noise_sweep" +``` + +For parameter sweeps that do not need to keep independent catalog snapshots, +prefer building one structural catalog and calling `with_noise()` for each +noise point. Use `parameterized()` when the code needs independent catalogs +alive at the same time. diff --git a/crates/benchmarks/benches/modules/fault_catalog.rs b/crates/benchmarks/benches/modules/fault_catalog.rs index d8225e033..58f428eac 100644 --- a/crates/benchmarks/benches/modules/fault_catalog.rs +++ b/crates/benchmarks/benches/modules/fault_catalog.rs @@ -191,6 +191,25 @@ fn bench_noise_sweeps(c: &mut Criterion) { }, ); + group.bench_with_input( + BenchmarkId::new("mutable_catalog_sweep", id.clone()), + &memory, + |b, memory| { + b.iter(|| { + let mut catalog = FaultCatalog::from_circuit(black_box(&memory.circuit)) + .expect("surface memory circuit should be supported"); + let mut total_locations = 0usize; + let mut total_alternatives = 0usize; + for noise in SWEEP_NOISES { + catalog.with_noise(black_box(noise)); + total_locations += catalog.locations.len(); + total_alternatives += count_alternatives(&catalog); + } + black_box((total_locations, total_alternatives)) + }); + }, + ); + group.bench_with_input( BenchmarkId::new("direct_raw_mechanism_sweep", id.clone()), &memory, @@ -213,7 +232,7 @@ fn bench_noise_sweeps(c: &mut Criterion) { ); group.bench_with_input( - BenchmarkId::new("parameterized_raw_mechanism_sweep", id), + BenchmarkId::new("parameterized_raw_mechanism_sweep", id.clone()), &memory, |b, memory| { b.iter(|| { @@ -234,6 +253,29 @@ fn bench_noise_sweeps(c: &mut Criterion) { }); }, ); + + group.bench_with_input( + BenchmarkId::new("mutable_raw_mechanism_sweep", id), + &memory, + |b, memory| { + b.iter(|| { + let mut catalog = FaultCatalog::from_circuit(black_box(&memory.circuit)) + .expect("surface memory circuit should be supported"); + let mut total_mechanisms = 0usize; + let mut total_alternatives = 0usize; + for noise in SWEEP_NOISES { + catalog.with_noise(black_box(noise)); + let mechanisms = catalog.to_mechanisms(); + total_mechanisms += mechanisms.len(); + total_alternatives += mechanisms + .iter() + .map(|mechanism| mechanism.alternatives.len()) + .sum::(); + } + black_box((total_mechanisms, total_alternatives)) + }); + }, + ); } group.finish(); diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index 0944b41da..79a616ea4 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -164,6 +164,8 @@ pub struct StochasticNoiseParams { /// A gate in the flattened gate list (one entry per qubit-pair or single qubit). #[derive(Clone, Debug)] pub(crate) struct GateLoc { + pub(crate) tick: usize, + pub(crate) gate_index: usize, pub(crate) gate_type: GateType, pub(crate) qubits: Vec, } @@ -259,8 +261,8 @@ pub(crate) fn flatten_tick_circuit(tc: &TickCircuit) -> (Vec, HashMap = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); let is_mz = is_supported_measurement_gate(gate.gate_type); let is_2q = is_standard_2q_clifford_gate(gate.gate_type); @@ -270,6 +272,8 @@ pub(crate) fn flatten_tick_circuit(tc: &TickCircuit) -> (Vec, HashMap (Vec, HashMap 2 { for pair in qs.chunks(2).filter(|c| c.len() == 2) { gates.push(GateLoc { + tick: tick_idx, + gate_index: gate_idx, gate_type: gate.gate_type, qubits: vec![pair[0], pair[1]], }); @@ -284,6 +290,8 @@ pub(crate) fn flatten_tick_circuit(tc: &TickCircuit) -> (Vec, HashMap 1 && !is_2q && !is_mz { for &q in &qs { gates.push(GateLoc { + tick: tick_idx, + gate_index: gate_idx, gate_type: gate.gate_type, qubits: vec![q], }); @@ -294,6 +302,8 @@ pub(crate) fn flatten_tick_circuit(tc: &TickCircuit) -> (Vec, HashMap Result = Vec::new(); - for (tick_idx, tick) in tc.ticks().iter().enumerate() { - for (gate_idx, _gate) in tick.gates().iter().enumerate() { - tick_gate_map.push((tick_idx, gate_idx)); - } - } - - // Re-walk the flattened gate list (same order as build_fault_table) - // but record location metadata and Pauli labels - let mut flat_idx_to_tick_gate: Vec<(usize, usize, GateType, Vec)> = Vec::new(); - { - let mut orig_idx = 0; - for tick in tc.ticks() { - for gate in tick.gates() { - let qs: Vec = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); - let is_mz = is_supported_measurement_gate(gate.gate_type); - let is_2q = is_standard_2q_clifford_gate(gate.gate_type); - let (tick_idx, gate_idx) = tick_gate_map[orig_idx]; - - if is_mz && qs.len() > 1 { - for &q in &qs { - flat_idx_to_tick_gate.push((tick_idx, gate_idx, gate.gate_type, vec![q])); - } - } else if is_2q && qs.len() > 2 { - for pair in qs.chunks(2).filter(|c| c.len() == 2) { - flat_idx_to_tick_gate.push(( - tick_idx, - gate_idx, - gate.gate_type, - vec![pair[0], pair[1]], - )); - } - } else if qs.len() > 1 && !is_2q && !is_mz { - for &q in &qs { - flat_idx_to_tick_gate.push((tick_idx, gate_idx, gate.gate_type, vec![q])); - } - } else { - flat_idx_to_tick_gate.push((tick_idx, gate_idx, gate.gate_type, qs)); - } - orig_idx += 1; - } - } - } - let pauli_types = [PauliType::X, PauliType::Y, PauliType::Z]; let mut effect_cache = PropagatedEffectCache::default(); for (loc_idx, loc) in gates.iter().enumerate() { - let (tick_idx, gate_idx, gate_type, ref qubits) = flat_idx_to_tick_gate[loc_idx]; + let tick_idx = loc.tick; + let gate_idx = loc.gate_index; + let gate_type = loc.gate_type; + let qubits = &loc.qubits; - match loc.gate_type { + match gate_type { gate_type if is_standard_1q_clifford_gate(gate_type) && !loc.qubits.is_empty() => { let q = loc.qubits[0]; let num_alts = 3; @@ -2054,6 +2022,51 @@ mod tests { } } + #[test] + fn test_flatten_tick_circuit_preserves_source_metadata() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0), QubitId(1)]); + tc.tick() + .cx(&[(QubitId(0), QubitId(1)), (QubitId(2), QubitId(3))]); + tc.tick().mz(&[QubitId(0), QubitId(1)]); + + let (gates, meas_positions) = flatten_tick_circuit(&tc); + + assert_eq!(gates.len(), 6); + assert_eq!(meas_positions.get(&4), Some(&0)); + assert_eq!(meas_positions.get(&5), Some(&1)); + + assert_eq!(gates[0].tick, 0); + assert_eq!(gates[0].gate_index, 0); + assert_eq!(gates[0].gate_type, GateType::H); + assert_eq!(gates[0].qubits, vec![0]); + + assert_eq!(gates[1].tick, 0); + assert_eq!(gates[1].gate_index, 0); + assert_eq!(gates[1].gate_type, GateType::H); + assert_eq!(gates[1].qubits, vec![1]); + + assert_eq!(gates[2].tick, 1); + assert_eq!(gates[2].gate_index, 0); + assert_eq!(gates[2].gate_type, GateType::CX); + assert_eq!(gates[2].qubits, vec![0, 1]); + + assert_eq!(gates[3].tick, 1); + assert_eq!(gates[3].gate_index, 0); + assert_eq!(gates[3].gate_type, GateType::CX); + assert_eq!(gates[3].qubits, vec![2, 3]); + + assert_eq!(gates[4].tick, 2); + assert_eq!(gates[4].gate_index, 0); + assert_eq!(gates[4].gate_type, GateType::MZ); + assert_eq!(gates[4].qubits, vec![0]); + + assert_eq!(gates[5].tick, 2); + assert_eq!(gates[5].gate_index, 0); + assert_eq!(gates[5].gate_type, GateType::MZ); + assert_eq!(gates[5].qubits, vec![1]); + } + // ---- Direct propagation tests using propagate_single ---- #[test] diff --git a/crates/pecos-quantum/src/diamond_norm.rs b/crates/pecos-quantum/src/diamond_norm.rs index 34ea27c22..5f6ba6bef 100644 --- a/crates/pecos-quantum/src/diamond_norm.rs +++ b/crates/pecos-quantum/src/diamond_norm.rs @@ -309,8 +309,8 @@ pub fn hermitian_to_real_symmetric_with_tolerance( /// row-vector convention used by the Watrous diamond-norm SDP objective. /// /// PECOS indexes Choi rows and columns as `output + input * dim_output`. -/// This helper performs the same convention transform described in Qiskit's -/// diamond-norm implementation: +/// This helper performs the convention transform used when assembling the +/// row-vector form of the Watrous SDP: /// /// ```text /// reshape(J, (dim_in, dim_out, dim_in, dim_out)) diff --git a/docs/user-guide/quantum-info.md b/docs/user-guide/quantum-info.md index 6dd236c9b..65d490844 100644 --- a/docs/user-guide/quantum-info.md +++ b/docs/user-guide/quantum-info.md @@ -55,6 +55,12 @@ print(pauli_channel_diamond_norm(left, right)) print(pauli_channel_diamond_distance(left, right)) ``` +Arbitrary-channel diamond norm is intentionally not exposed yet. General +channels require a semidefinite program, and PECOS will only expose that API +once the solver and SDP assembly live in Rust with PECOS-owned validation. The +current Rust groundwork covers the exact Pauli-channel formula plus internal +linear-algebra helpers for future SDP assembly. + For multi-qubit Pauli channels, pass a label-to-probability map: ```python @@ -114,6 +120,13 @@ reconstructed = design.reconstruct_choi(outputs) assert reconstructed.matrix() == choi.matrix() ``` +Physical process tomography is a separate layer. A physical workflow prepares +experimentally realizable input states, measures in chosen bases, aggregates +shot counts, and reconstructs an estimated channel before converting it into +`Ptm`, `ChoiMatrix`, or another channel representation. The current +`ProcessTomographyDesign` is the Rust-backed exact reconstruction primitive +that those higher-level experiment-design helpers should build on. + The dense channel forms convert through the same Rust-backed validation path: ```python From bde3459560478e3af1441160f55b4114dd306402 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 14:38:50 -0600 Subject: [PATCH 091/125] Check root Python workspace version --- .github/workflows/python-version-consistency.yml | 14 +++++++++++--- pyproject.toml | 2 +- 2 files changed, 12 insertions(+), 4 deletions(-) diff --git a/.github/workflows/python-version-consistency.yml b/.github/workflows/python-version-consistency.yml index 65989d385..1ccd8342a 100644 --- a/.github/workflows/python-version-consistency.yml +++ b/.github/workflows/python-version-consistency.yml @@ -3,9 +3,11 @@ name: Python Version Consistency Check on: push: paths: + - 'pyproject.toml' - 'python/**/pyproject.toml' pull_request: paths: + - 'pyproject.toml' - 'python/**/pyproject.toml' jobs: @@ -17,8 +19,8 @@ jobs: - name: Check version consistency run: | - # Find all pyproject.toml files in the python/ directory - PYPROJECT_FILES=$(find python -name pyproject.toml) + # Check the root uv workspace project plus all Python packages. + PYPROJECT_FILES="pyproject.toml $(find python -name pyproject.toml | sort)" # Initialize variables FIRST_VERSION="" @@ -26,7 +28,13 @@ jobs: # Check each pyproject.toml file for file in $PYPROJECT_FILES; do - VERSION=$(grep -oP 'version = "\K[^"]+' $file) + VERSION=$(grep -oP '^version = "\K[^"]+' "$file") + + if [ -z "$VERSION" ]; then + echo "Error: No project version found in $file" + INCONSISTENT=true + continue + fi if [ -z "$FIRST_VERSION" ]; then FIRST_VERSION=$VERSION diff --git a/pyproject.toml b/pyproject.toml index 6228d25b1..ae907f163 100644 --- a/pyproject.toml +++ b/pyproject.toml @@ -1,6 +1,6 @@ [project] name = "pecos-workspace" -version = "0.8.0.dev5" +version = "0.8.0.dev8" # Meta-package; runtime deps live in the member packages. Test/example/dev # tooling is declared in [dependency-groups] below. dependencies = [] From a687fd8ef79f0e48931872a79951020573844f62 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 14:46:34 -0600 Subject: [PATCH 092/125] Harden Python workspace metadata checks --- .../workflows/python-version-consistency.yml | 46 ++---- Justfile | 7 +- pyproject.toml | 1 + scripts/check_python_workspace.py | 147 ++++++++++++++++++ uv.lock | 2 +- 5 files changed, 165 insertions(+), 38 deletions(-) create mode 100644 scripts/check_python_workspace.py diff --git a/.github/workflows/python-version-consistency.yml b/.github/workflows/python-version-consistency.yml index 1ccd8342a..931b0fb5a 100644 --- a/.github/workflows/python-version-consistency.yml +++ b/.github/workflows/python-version-consistency.yml @@ -5,10 +5,14 @@ on: paths: - 'pyproject.toml' - 'python/**/pyproject.toml' + - 'scripts/check_python_workspace.py' + - '.github/workflows/python-version-consistency.yml' pull_request: paths: - 'pyproject.toml' - 'python/**/pyproject.toml' + - 'scripts/check_python_workspace.py' + - '.github/workflows/python-version-consistency.yml' jobs: check_versions: @@ -17,40 +21,10 @@ jobs: - name: Checkout code uses: actions/checkout@v6 - - name: Check version consistency - run: | - # Check the root uv workspace project plus all Python packages. - PYPROJECT_FILES="pyproject.toml $(find python -name pyproject.toml | sort)" + - name: Set up Python + uses: actions/setup-python@v6 + with: + python-version: "3.11" - # Initialize variables - FIRST_VERSION="" - INCONSISTENT=false - - # Check each pyproject.toml file - for file in $PYPROJECT_FILES; do - VERSION=$(grep -oP '^version = "\K[^"]+' "$file") - - if [ -z "$VERSION" ]; then - echo "Error: No project version found in $file" - INCONSISTENT=true - continue - fi - - if [ -z "$FIRST_VERSION" ]; then - FIRST_VERSION=$VERSION - echo "Reference version: $FIRST_VERSION (from $file)" - elif [ "$VERSION" != "$FIRST_VERSION" ]; then - echo "Inconsistent version found in $file: $VERSION" - INCONSISTENT=true - else - echo "Consistent version found in $file: $VERSION" - fi - done - - # Exit with error if versions are inconsistent - if [ "$INCONSISTENT" = true ]; then - echo "Error: Inconsistent versions found across pyproject.toml files" - exit 1 - else - echo "Success: All pyproject.toml files have consistent versions" - fi + - name: Check Python workspace metadata + run: python scripts/check_python_workspace.py diff --git a/Justfile b/Justfile index 7033955a0..b395b7289 100644 --- a/Justfile +++ b/Justfile @@ -195,7 +195,7 @@ test mode="release": (rstest mode) pytest # Fix formatting and linting issues (or: just lint check) [group('lint')] -lint mode="fix": +lint mode="fix": python-workspace-check #!/usr/bin/env bash set -euo pipefail # Detect CUDA: only use --all-features when CUDA toolkit is available @@ -245,6 +245,11 @@ lint mode="fix": check: cargo check --workspace --all-targets +# Check Python workspace metadata +[group('lint')] +python-workspace-check: + @if command -v python3 >/dev/null 2>&1; then python3 scripts/check_python_workspace.py; else python scripts/check_python_workspace.py; fi + # Run cargo clippy (CUDA-aware: uses --all-features only when CUDA is available) [group('lint')] clippy: diff --git a/pyproject.toml b/pyproject.toml index ae907f163..59e52bcdb 100644 --- a/pyproject.toml +++ b/pyproject.toml @@ -1,6 +1,7 @@ [project] name = "pecos-workspace" version = "0.8.0.dev8" +requires-python = ">=3.10" # Meta-package; runtime deps live in the member packages. Test/example/dev # tooling is declared in [dependency-groups] below. dependencies = [] diff --git a/scripts/check_python_workspace.py b/scripts/check_python_workspace.py new file mode 100644 index 000000000..c68e6a98a --- /dev/null +++ b/scripts/check_python_workspace.py @@ -0,0 +1,147 @@ +#!/usr/bin/env python3 +# Copyright 2026 The PECOS Developers +# Licensed under the Apache License, Version 2.0 +"""Validate Python workspace metadata.""" + +from __future__ import annotations + +import re +import sys +from pathlib import Path +from typing import Any + +try: + import tomllib +except ModuleNotFoundError: # pragma: no cover + try: + import tomli as tomllib # type: ignore[no-redef] + except ModuleNotFoundError: + print("Python 3.11+ or tomli is required to parse pyproject.toml files", file=sys.stderr) + sys.exit(2) + + +PROJECT_NAME_RE = re.compile(r"^\s*([A-Za-z0-9_.-]+)") + + +def normalize_name(name: str) -> str: + return re.sub(r"[-_.]+", "-", name).lower() + + +def load_toml(path: Path) -> dict[str, Any]: + with path.open("rb") as handle: + return tomllib.load(handle) + + +def project_metadata(path: Path, errors: list[str]) -> tuple[str, str] | None: + data = load_toml(path) + project = data.get("project") + if not isinstance(project, dict): + errors.append(f"{path}: missing [project] table") + return None + + name = project.get("name") + version = project.get("version") + if not isinstance(name, str) or not name: + errors.append(f"{path}: missing project.name") + return None + if not isinstance(version, str) or not version: + errors.append(f"{path}: missing project.version") + return None + return name, version + + +def dependency_strings(pyproject: dict[str, Any]) -> list[str]: + project = pyproject.get("project") + if not isinstance(project, dict): + return [] + + out: list[str] = [] + deps = project.get("dependencies", []) + if isinstance(deps, list): + out.extend(dep for dep in deps if isinstance(dep, str)) + + optional = project.get("optional-dependencies", {}) + if isinstance(optional, dict): + for values in optional.values(): + if isinstance(values, list): + out.extend(dep for dep in values if isinstance(dep, str)) + return out + + +def dependency_name(requirement: str) -> str | None: + match = PROJECT_NAME_RE.match(requirement) + if match is None: + return None + return normalize_name(match.group(1)) + + +def main() -> int: + repo_root = Path(__file__).resolve().parents[1] + root_pyproject = repo_root / "pyproject.toml" + python_pyprojects = sorted((repo_root / "python").rglob("pyproject.toml")) + all_pyprojects = [root_pyproject, *python_pyprojects] + + errors: list[str] = [] + + versions: dict[str, str] = {} + project_paths: dict[str, Path] = {} + for path in all_pyprojects: + metadata = project_metadata(path, errors) + if metadata is None: + continue + name, version = metadata + normalized = normalize_name(name) + versions[normalized] = version + project_paths[normalized] = path + + if versions: + expected_version = versions.get("pecos-workspace") or next(iter(versions.values())) + for name, version in sorted(versions.items()): + if version != expected_version: + errors.append( + f"{project_paths[name].relative_to(repo_root)}: version {version} " + f"does not match workspace version {expected_version}", + ) + + root_data = load_toml(root_pyproject) + uv_workspace = root_data.get("tool", {}).get("uv", {}).get("workspace", {}) + uv_members = uv_workspace.get("members", []) + if not isinstance(uv_members, list) or not all(isinstance(member, str) for member in uv_members): + errors.append("pyproject.toml: [tool.uv.workspace].members must be a list of strings") + else: + actual_members = {path.parent.relative_to(repo_root).as_posix() for path in python_pyprojects} + configured_members = set(uv_members) + missing = sorted(actual_members - configured_members) + extra = sorted(configured_members - actual_members) + if missing: + errors.append(f"pyproject.toml: missing uv workspace members: {missing}") + if extra: + errors.append(f"pyproject.toml: unknown uv workspace members: {extra}") + + for name, path in sorted(project_paths.items()): + if name == "pecos-workspace": + continue + pyproject = load_toml(path) + for requirement in dependency_strings(pyproject): + dep_name = dependency_name(requirement) + if dep_name is None or dep_name == name or dep_name not in versions: + continue + expected = versions[dep_name] + if f"=={expected}" not in requirement: + errors.append( + f"{path.relative_to(repo_root)}: internal dependency {requirement!r} " + f"must pin {dep_name}=={expected}", + ) + + if errors: + print("Python workspace metadata check failed:", file=sys.stderr) + for error in errors: + print(f" - {error}", file=sys.stderr) + return 1 + + print(f"Python workspace metadata is consistent across {len(all_pyprojects)} pyproject.toml files") + return 0 + + +if __name__ == "__main__": + sys.exit(main()) diff --git a/uv.lock b/uv.lock index 677eff7f2..ec8023b9d 100644 --- a/uv.lock +++ b/uv.lock @@ -2910,7 +2910,7 @@ provides-extras = ["test"] [[package]] name = "pecos-workspace" -version = "0.8.0.dev5" +version = "0.8.0.dev8" source = { virtual = "." } [package.optional-dependencies] From 6966369fd17b321b4267a9b623ac14f57957a419 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 15:02:20 -0600 Subject: [PATCH 093/125] Harden Python workspace metadata tooling --- .../workflows/python-version-consistency.yml | 2 +- pyproject.toml | 17 +- python/pecos-rslib-cuda/pyproject.toml | 3 - python/pecos-rslib-llvm/pyproject.toml | 3 - scripts/check_python_workspace.py | 260 ++++++++++++------ 5 files changed, 190 insertions(+), 95 deletions(-) diff --git a/.github/workflows/python-version-consistency.yml b/.github/workflows/python-version-consistency.yml index 931b0fb5a..16bd806e9 100644 --- a/.github/workflows/python-version-consistency.yml +++ b/.github/workflows/python-version-consistency.yml @@ -15,7 +15,7 @@ on: - '.github/workflows/python-version-consistency.yml' jobs: - check_versions: + check_python_workspace: runs-on: ubuntu-latest steps: - name: Checkout code diff --git a/pyproject.toml b/pyproject.toml index 59e52bcdb..890192207 100644 --- a/pyproject.toml +++ b/pyproject.toml @@ -7,7 +7,9 @@ requires-python = ">=3.10" dependencies = [] [project.optional-dependencies] -cuda = ["quantum-pecos[cuda]"] +# Keep this in sync with the cuda dependency group below. The extra supports +# `uv sync --extra cuda`; the group supports `uv run --group cuda ...`. +cuda = ["quantum-pecos[cuda]==0.8.0.dev8"] [tool.uv.workspace] members = [ @@ -65,15 +67,20 @@ numpy-compat = [ # NumPy/SciPy compatibility tests - verify compatibility with s "scipy>=1.1.0", ] cuda = [ # CUDA Python packages for GPU-accelerated simulations (requires CUDA toolkit) - "quantum-pecos[cuda]", + "quantum-pecos[cuda]==0.8.0.dev8", ] [tool.uv] default-groups = ["dev", "test"] -# Prevent uv from caching pecos-rslib wheels - always use freshly built version -# This fixes stale code issues when uv sync/run reinstalls cached old wheels +# Prevent uv from caching native workspace wheels - always use freshly built versions. +# This fixes stale code issues when uv sync/run reinstalls cached old wheels. # See: https://github.com/astral-sh/uv/issues/11390 -reinstall-package = ["pecos-rslib", "pecos-rslib-cuda", "pecos-rslib-llvm"] +reinstall-package = [ + "pecos-rslib", + "pecos-rslib-cuda", + "pecos-rslib-exp", + "pecos-rslib-llvm", +] [tool.black] line-length = 120 diff --git a/python/pecos-rslib-cuda/pyproject.toml b/python/pecos-rslib-cuda/pyproject.toml index 3e96e850b..7d48eccb5 100644 --- a/python/pecos-rslib-cuda/pyproject.toml +++ b/python/pecos-rslib-cuda/pyproject.toml @@ -43,9 +43,6 @@ test = [ "pytest>=9.0", ] -[tool.uv.sources] -pecos-rslib-cuda = { workspace = true } - [tool.pytest.ini_options] markers = [ "cuda: marks tests that require CUDA and cuQuantum (deselect with '-m \"not cuda\"')", diff --git a/python/pecos-rslib-llvm/pyproject.toml b/python/pecos-rslib-llvm/pyproject.toml index de6566bad..553757192 100644 --- a/python/pecos-rslib-llvm/pyproject.toml +++ b/python/pecos-rslib-llvm/pyproject.toml @@ -42,9 +42,6 @@ test = [ "pytest>=9.0", ] -[tool.uv.sources] -pecos-rslib-llvm = { workspace = true } - [tool.ruff] lint.extend-select = ["S", "B", "PT"] lint.ignore = ["S101"] diff --git a/scripts/check_python_workspace.py b/scripts/check_python_workspace.py index c68e6a98a..5d0259b09 100644 --- a/scripts/check_python_workspace.py +++ b/scripts/check_python_workspace.py @@ -1,26 +1,44 @@ #!/usr/bin/env python3 # Copyright 2026 The PECOS Developers # Licensed under the Apache License, Version 2.0 -"""Validate Python workspace metadata.""" +"""Validate PECOS Python workspace metadata. + +This check is intentionally narrower than a full packaging linter. It guards +the invariants that tend to drift in this repository: package versions, +workspace membership, internal dependency pins, and uv workspace sources. +""" from __future__ import annotations import re import sys +from dataclasses import dataclass from pathlib import Path from typing import Any try: import tomllib -except ModuleNotFoundError: # pragma: no cover +except ModuleNotFoundError: # pragma: no cover - Python 3.10 fallback try: import tomli as tomllib # type: ignore[no-redef] except ModuleNotFoundError: - print("Python 3.11+ or tomli is required to parse pyproject.toml files", file=sys.stderr) + print("error: Python 3.11+ or the 'tomli' package is required", file=sys.stderr) sys.exit(2) -PROJECT_NAME_RE = re.compile(r"^\s*([A-Za-z0-9_.-]+)") +REPO_ROOT = Path(__file__).resolve().parents[1] +ROOT_PYPROJECT = REPO_ROOT / "pyproject.toml" +DEPENDENCY_NAME_RE = re.compile(r"^\s*([A-Za-z0-9_.-]+)") + + +@dataclass(frozen=True) +class Package: + path: Path + rel_dir: str + name: str + normalized_name: str + version: str + data: dict[str, Any] def normalize_name(name: str) -> str: @@ -32,116 +50,192 @@ def load_toml(path: Path) -> dict[str, Any]: return tomllib.load(handle) -def project_metadata(path: Path, errors: list[str]) -> tuple[str, str] | None: +def fail(errors: list[str], message: str) -> None: + errors.append(message) + + +def rel(path: Path) -> str: + return path.relative_to(REPO_ROOT).as_posix() + + +def load_package(path: Path, errors: list[str]) -> Package | None: data = load_toml(path) project = data.get("project") if not isinstance(project, dict): - errors.append(f"{path}: missing [project] table") + fail(errors, f"{rel(path)}: missing [project] table") return None name = project.get("name") version = project.get("version") if not isinstance(name, str) or not name: - errors.append(f"{path}: missing project.name") + fail(errors, f"{rel(path)}: missing [project].name") return None if not isinstance(version, str) or not version: - errors.append(f"{path}: missing project.version") + fail(errors, f"{rel(path)}: missing [project].version") return None - return name, version - - -def dependency_strings(pyproject: dict[str, Any]) -> list[str]: - project = pyproject.get("project") - if not isinstance(project, dict): - return [] - out: list[str] = [] - deps = project.get("dependencies", []) - if isinstance(deps, list): - out.extend(dep for dep in deps if isinstance(dep, str)) - - optional = project.get("optional-dependencies", {}) - if isinstance(optional, dict): - for values in optional.values(): - if isinstance(values, list): - out.extend(dep for dep in values if isinstance(dep, str)) - return out + return Package( + path=path, + rel_dir=rel(path.parent), + name=name, + normalized_name=normalize_name(name), + version=version, + data=data, + ) def dependency_name(requirement: str) -> str | None: - match = PROJECT_NAME_RE.match(requirement) + match = DEPENDENCY_NAME_RE.match(requirement) if match is None: return None return normalize_name(match.group(1)) -def main() -> int: - repo_root = Path(__file__).resolve().parents[1] - root_pyproject = repo_root / "pyproject.toml" - python_pyprojects = sorted((repo_root / "python").rglob("pyproject.toml")) - all_pyprojects = [root_pyproject, *python_pyprojects] +def has_exact_version_pin(requirement: str, version: str) -> bool: + return re.search(rf"(^|[^=!<>~])==\s*{re.escape(version)}(\s*(;|,|$))", requirement) is not None - errors: list[str] = [] - versions: dict[str, str] = {} - project_paths: dict[str, Path] = {} - for path in all_pyprojects: - metadata = project_metadata(path, errors) - if metadata is None: - continue - name, version = metadata - normalized = normalize_name(name) - versions[normalized] = version - project_paths[normalized] = path - - if versions: - expected_version = versions.get("pecos-workspace") or next(iter(versions.values())) - for name, version in sorted(versions.items()): - if version != expected_version: - errors.append( - f"{project_paths[name].relative_to(repo_root)}: version {version} " - f"does not match workspace version {expected_version}", - ) +def iter_dependency_lists(data: dict[str, Any]) -> list[tuple[str, list[Any]]]: + lists: list[tuple[str, list[Any]]] = [] + project = data.get("project", {}) + if isinstance(project, dict): + dependencies = project.get("dependencies", []) + if isinstance(dependencies, list): + lists.append(("[project].dependencies", dependencies)) - root_data = load_toml(root_pyproject) - uv_workspace = root_data.get("tool", {}).get("uv", {}).get("workspace", {}) - uv_members = uv_workspace.get("members", []) - if not isinstance(uv_members, list) or not all(isinstance(member, str) for member in uv_members): - errors.append("pyproject.toml: [tool.uv.workspace].members must be a list of strings") - else: - actual_members = {path.parent.relative_to(repo_root).as_posix() for path in python_pyprojects} - configured_members = set(uv_members) - missing = sorted(actual_members - configured_members) - extra = sorted(configured_members - actual_members) - if missing: - errors.append(f"pyproject.toml: missing uv workspace members: {missing}") - if extra: - errors.append(f"pyproject.toml: unknown uv workspace members: {extra}") - - for name, path in sorted(project_paths.items()): - if name == "pecos-workspace": - continue - pyproject = load_toml(path) - for requirement in dependency_strings(pyproject): - dep_name = dependency_name(requirement) - if dep_name is None or dep_name == name or dep_name not in versions: + optional = project.get("optional-dependencies", {}) + if isinstance(optional, dict): + for extra, deps in sorted(optional.items()): + if isinstance(deps, list): + lists.append((f"[project.optional-dependencies].{extra}", deps)) + + dependency_groups = data.get("dependency-groups", {}) + if isinstance(dependency_groups, dict): + for group, deps in sorted(dependency_groups.items()): + if isinstance(deps, list): + lists.append((f"[dependency-groups].{group}", deps)) + + return lists + + +def internal_dependencies(package: Package, workspace_names: set[str], errors: list[str]) -> set[str]: + internal: set[str] = set() + for section, deps in iter_dependency_lists(package.data): + for dep in deps: + if not isinstance(dep, str): + fail(errors, f"{rel(package.path)}: {section} contains non-string dependency {dep!r}") + continue + dep_name = dependency_name(dep) + if dep_name is None or dep_name not in workspace_names or dep_name == package.normalized_name: continue - expected = versions[dep_name] - if f"=={expected}" not in requirement: - errors.append( - f"{path.relative_to(repo_root)}: internal dependency {requirement!r} " - f"must pin {dep_name}=={expected}", + internal.add(dep_name) + if not has_exact_version_pin(dep, package.version): + fail( + errors, + f"{rel(package.path)}: {section} dependency {dep!r} must pin " + f"workspace package version =={package.version}", ) + return internal + + +def workspace_sources(package: Package, errors: list[str]) -> set[str]: + tool = package.data.get("tool", {}) + uv = tool.get("uv", {}) if isinstance(tool, dict) else {} + sources = uv.get("sources", {}) if isinstance(uv, dict) else {} + if not isinstance(sources, dict): + fail(errors, f"{rel(package.path)}: [tool.uv.sources] must be a table") + return set() + + names: set[str] = set() + for name, source in sources.items(): + normalized = normalize_name(name) + if not isinstance(source, dict) or source.get("workspace") is not True: + continue + names.add(normalized) + return names + + +def check_cuda_extra_group(root_data: dict[str, Any], errors: list[str]) -> None: + project = root_data.get("project", {}) + optional = project.get("optional-dependencies", {}) if isinstance(project, dict) else {} + dependency_groups = root_data.get("dependency-groups", {}) + cuda_extra = optional.get("cuda") if isinstance(optional, dict) else None + cuda_group = dependency_groups.get("cuda") if isinstance(dependency_groups, dict) else None + + if cuda_extra is None or cuda_group is None: + return + if cuda_extra != cuda_group: + fail( + errors, + "pyproject.toml: [project.optional-dependencies].cuda and [dependency-groups].cuda must stay identical", + ) + + +def main() -> int: + errors: list[str] = [] + + root = load_package(ROOT_PYPROJECT, errors) + package_paths = sorted((REPO_ROOT / "python").rglob("pyproject.toml")) + packages = [pkg for path in package_paths if (pkg := load_package(path, errors)) is not None] + if root is None: + for error in errors: + print(f"error: {error}", file=sys.stderr) + return 1 + + all_packages = [root, *packages] + workspace_names = {pkg.normalized_name for pkg in all_packages} + + for pkg in all_packages: + if pkg.version != root.version: + fail( + errors, + f"{rel(pkg.path)}: version {pkg.version!r} does not match root version {root.version!r}", + ) + + root_tool = root.data.get("tool", {}) + root_uv = root_tool.get("uv", {}) if isinstance(root_tool, dict) else {} + workspace = root_uv.get("workspace", {}) if isinstance(root_uv, dict) else {} + members = workspace.get("members") if isinstance(workspace, dict) else None + expected_members = sorted(pkg.rel_dir for pkg in packages) + if not isinstance(members, list) or any(not isinstance(member, str) for member in members): + fail(errors, "pyproject.toml: [tool.uv.workspace].members must be a string list") + elif sorted(members) != expected_members: + fail( + errors, + "pyproject.toml: [tool.uv.workspace].members does not match Python package directories\n" + f" expected: {expected_members}\n" + f" found: {sorted(members)}", + ) + + check_cuda_extra_group(root.data, errors) + + for pkg in all_packages: + internal = internal_dependencies(pkg, workspace_names, errors) + sources = workspace_sources(pkg, errors) + missing_sources = sorted(internal - sources) + extra_sources = sorted((sources & workspace_names) - internal) + if missing_sources: + fail( + errors, + f"{rel(pkg.path)}: missing [tool.uv.sources] workspace entries for {missing_sources}", + ) + if extra_sources: + fail( + errors, + f"{rel(pkg.path)}: unused internal [tool.uv.sources] workspace entries {extra_sources}", + ) if errors: - print("Python workspace metadata check failed:", file=sys.stderr) for error in errors: - print(f" - {error}", file=sys.stderr) + print(f"error: {error}", file=sys.stderr) return 1 - print(f"Python workspace metadata is consistent across {len(all_pyprojects)} pyproject.toml files") + print( + f"Python workspace metadata OK: {len(packages)} packages, " + f"version {root.version}, {len(expected_members)} uv workspace members", + ) return 0 if __name__ == "__main__": - sys.exit(main()) + raise SystemExit(main()) From 7b2a30b00bda6e20cb4aa64df4bb0022a8e9011b Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 15:54:45 -0600 Subject: [PATCH 094/125] Make idle noise explicit in DEM builders --- .../fault_tolerance/dem_builder/builder.rs | 41 +++++-- .../dem_builder/dem_sampler.rs | 67 +++++++--- .../fault_tolerance/dem_builder/sampler.rs | 6 +- .../src/fault_tolerance/dem_builder/types.rs | 55 +++++++-- crates/pecos-qec/tests/idle_noise_tests.rs | 114 +++++++++++++++--- .../src/pecos/qec/surface/circuit_builder.py | 9 +- .../src/pecos/qec/surface/decode.py | 47 ++++++-- .../tests/qec/surface/test_surface_decoder.py | 43 +++++++ 8 files changed, 314 insertions(+), 68 deletions(-) diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs index d8665379a..8722a27a6 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs @@ -235,6 +235,35 @@ impl<'a> DemBuilder<'a> { [per, per, per] } + /// Resolve `[rate_X, rate_Y, rate_Z]` for an explicit idle location. + fn idle_rates_for_loc(&self, loc: &DagSpacetimeLocation) -> [f64; 3] { + if let Some(pg) = &self.per_gate { + let explicit_rates = loc + .qubits + .first() + .and_then(|q| pg.explicit_1q_rates_on(GateType::Idle, *q)) + .or_else(|| pg.explicit_1q_rates(GateType::Idle)); + if let Some(rates) = explicit_rates { + return rates; + } + if pg.base.uses_dedicated_idle_noise() { + #[allow(clippy::cast_precision_loss)] + let duration = loc.idle_duration.max(1) as f64; + let probs = pg.base.idle_pauli_probs(duration); + return [probs.px, probs.py, probs.pz]; + } + return [0.0; 3]; + } + + if self.noise.uses_dedicated_idle_noise() { + #[allow(clippy::cast_precision_loss)] + let duration = loc.idle_duration.max(1) as f64; + let probs = self.noise.idle_pauli_probs(duration); + return [probs.px, probs.py, probs.pz]; + } + [0.0; 3] + } + /// Resolve the 15-entry 2Q per-Pauli-pair rate array for a gate /// spanning two fault locations. fn rates_2q_for_locs( @@ -512,17 +541,7 @@ impl<'a> DemBuilder<'a> { } } GateType::Idle if !loc.before => { - let rates = if self.per_gate.is_some() { - self.rates_1q_for_loc(loc) - } else if self.noise.uses_dedicated_idle_noise() { - // Duration values are small integers; precision loss is not a concern. - #[allow(clippy::cast_precision_loss)] - let duration = loc.idle_duration.max(1) as f64; - let pauli_probs = self.noise.idle_pauli_probs(duration); - [pauli_probs.px, pauli_probs.py, pauli_probs.pz] - } else { - self.rates_1q_for_loc(loc) - }; + let rates = self.idle_rates_for_loc(loc); if rates.iter().any(|r| *r > 0.0) { self.process_single_qubit_fault_source_tracked( loc_idx, diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index b1815bc5b..972016aa6 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -71,7 +71,7 @@ use smallvec::SmallVec; use std::collections::{BTreeMap, BTreeSet}; use wide::u64x4; -use super::types::{PerGateTypeNoise, combine_probabilities}; +use super::types::{NoiseConfig, PerGateTypeNoise, combine_probabilities}; // ============================================================================ // DEM Mechanism (used during building) @@ -1838,7 +1838,7 @@ pub(crate) struct SamplingEngineBuilder<'a> { p2: f64, p_meas: f64, p_prep: f64, - p_idle: Option, + idle_noise: Option, detector_records: Vec>, observable_records: Vec>, measurement_order: Option>, @@ -1861,7 +1861,7 @@ impl<'a> SamplingEngineBuilder<'a> { p2: 0.01, p_meas: 0.01, p_prep: 0.01, - p_idle: None, + idle_noise: None, per_gate: None, detector_records: Vec::new(), observable_records: Vec::new(), @@ -1883,7 +1883,14 @@ impl<'a> SamplingEngineBuilder<'a> { /// Set idle gate noise rate. #[must_use] pub fn with_idle_noise(mut self, p_idle: f64) -> Self { - self.p_idle = Some(p_idle); + self.idle_noise = Some(NoiseConfig::new(0.0, 0.0, 0.0, 0.0).set_idle(p_idle)); + self + } + + /// Set the full idle-noise model for idle gates. + #[must_use] + pub fn with_idle_noise_config(mut self, noise: NoiseConfig) -> Self { + self.idle_noise = Some(noise); self } @@ -2056,22 +2063,12 @@ impl<'a> SamplingEngineBuilder<'a> { } } GateType::Idle - // Idle gate errors: only "after" locations, depolarizing. - // Probability scales with duration: p = p_idle_rate * duration, - // clamped to [0, 1]. + // Idle gate errors: only "after" locations. Idle is + // noiseless unless idle noise or per-gate Idle rates are + // explicitly configured. if !loc.before => { - let rates = if self.per_gate.is_some() { - self.rates_1q(loc.gate_type, &loc.qubits) - } else if self.p_idle.is_some_and(|p| p > 0.0) { - // Duration values are small integers; precision loss is not a concern. - #[allow(clippy::cast_precision_loss)] - let duration = loc.idle_duration.max(1) as f64; - let p = (self.p_idle.unwrap() * duration).min(1.0); - [p / 3.0; 3] - } else { - self.rates_1q(loc.gate_type, &loc.qubits) - }; + let rates = self.idle_rates(loc); if rates.iter().any(|r| *r > 0.0) { self.process_depolarizing_fault_rates( loc_idx, @@ -2281,6 +2278,40 @@ impl<'a> SamplingEngineBuilder<'a> { } } + /// Resolve per-Pauli rates for an explicit idle location. + fn idle_rates( + &self, + loc: &crate::fault_tolerance::propagator::dag::DagSpacetimeLocation, + ) -> [f64; 3] { + if let Some(pg) = &self.per_gate { + let explicit_rates = loc + .qubits + .first() + .and_then(|q| pg.explicit_1q_rates_on(GateType::Idle, *q)) + .or_else(|| pg.explicit_1q_rates(GateType::Idle)); + if let Some(rates) = explicit_rates { + return rates; + } + if pg.base.uses_dedicated_idle_noise() { + #[allow(clippy::cast_precision_loss)] + let duration = loc.idle_duration.max(1) as f64; + let probs = pg.base.idle_pauli_probs(duration); + return [probs.px, probs.py, probs.pz]; + } + return [0.0; 3]; + } + + if let Some(noise) = &self.idle_noise + && noise.uses_dedicated_idle_noise() + { + #[allow(clippy::cast_precision_loss)] + let duration = loc.idle_duration.max(1) as f64; + let probs = noise.idle_pauli_probs(duration); + return [probs.px, probs.py, probs.pz]; + } + [0.0; 3] + } + /// Resolve per-Pauli-pair rates for a 2Q gate (15 non-II pairs) on a /// specific ordered qubit pair. fn rates_2q(&self, gate: GateType, qubits: &[pecos_core::QubitId]) -> [f64; 15] { diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs index 228dbe6af..63d5981f8 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs @@ -1196,8 +1196,8 @@ impl<'a> DemSamplerBuilder<'a> { if let Some(per_gate) = self.per_gate { builder = builder.with_per_gate_noise(per_gate); - } else if self.noise.p_idle > 0.0 { - builder = builder.with_idle_noise(self.noise.p_idle); + } else if self.noise.uses_dedicated_idle_noise() { + builder = builder.with_idle_noise_config(self.noise.clone()); } if let Some(order) = self.measurement_order { @@ -1290,7 +1290,7 @@ pub(crate) fn compute_location_probs_from_noise( let duration = loc.idle_duration.max(1) as f64; noise.idle_pauli_probs(duration).total() } else { - noise.p1 + 0.0 } } _ => noise.p1, diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs index 57ae442a5..b04f42b4f 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs @@ -1329,14 +1329,17 @@ impl std::error::Error for PecosDemMetadataError {} /// /// # Examples /// -/// ```ignore +/// ``` /// use pecos_core::pauli::{X, Y, Z}; +/// use pecos_qec::fault_tolerance::dem_builder::PauliWeights; /// /// // Single-qubit: biased toward dephasing /// let w = PauliWeights::from([(Z(0), 0.8), (X(0), 0.1), (Y(0), 0.1)]); +/// assert_eq!(w.entries().len(), 3); /// /// // Two-qubit: uniform (convenience) /// let w = PauliWeights::uniform_2q(); +/// assert_eq!(w.entries().len(), 15); /// ``` #[derive(Debug, Clone)] pub struct PauliWeights { @@ -1626,11 +1629,14 @@ impl NoiseConfig { /// Sets custom per-Pauli weights for single-qubit gates. /// - /// ```ignore + /// ``` /// use pecos_core::pauli::{X, Y, Z}; - /// noise.set_p1_weights(PauliWeights::from([ + /// use pecos_qec::fault_tolerance::dem_builder::{NoiseConfig, PauliWeights}; + /// + /// let noise = NoiseConfig::uniform(0.001).set_p1_weights(PauliWeights::from([ /// (X(0), 0.1), (Y(0), 0.1), (Z(0), 0.8), /// ])); + /// assert_eq!(noise.p1_weights.as_ref().unwrap().weight_for(&Z(7)), 0.8); /// ``` #[must_use] pub fn set_p1_weights(mut self, weights: PauliWeights) -> Self { @@ -1689,8 +1695,7 @@ impl NoiseConfig { /// Returns true when idle locations use the dedicated idle-noise model. /// - /// Otherwise `Idle` is modeled as an ordinary one-qubit gate and receives - /// the same Pauli error model as other one-qubit gates. + /// Otherwise `Idle` is a no-op for noise. #[must_use] pub fn uses_dedicated_idle_noise(&self) -> bool { self.p_idle > 0.0 || matches!((self.t1, self.t2), (Some(_), Some(_))) @@ -2058,6 +2063,24 @@ impl PerGateTypeNoise { self } + /// Return explicitly attached 1Q Pauli rates for a gate type. + #[must_use] + pub fn explicit_1q_rates(&self, gate: GateType) -> Option<[f64; 3]> { + self.rates_1q.get(&gate).copied() + } + + /// Return explicitly attached 1Q Pauli rates for a gate on a specific qubit. + /// + /// Per-qubit rates take precedence over gate-type rates. Unlike + /// [`Self::rate_1q_on`], this does not fall back to the base noise model. + #[must_use] + pub fn explicit_1q_rates_on(&self, gate: GateType, qubit: QubitId) -> Option<[f64; 3]> { + self.rates_1q_per_qubit + .get(&(gate, qubit)) + .copied() + .or_else(|| self.explicit_1q_rates(gate)) + } + /// Attach rates for a 2Q gate on a specific ordered qubit pair. /// Takes precedence over [`Self::with_2q_rates`] for that /// `(gate, q_control, q_target)` combination. @@ -2076,11 +2099,27 @@ impl PerGateTypeNoise { /// Lookup 1Q Pauli rate for a gate. Returns `base.p1 / 3.0` if the /// gate type is not in the map. `pauli_idx` is 0=X, 1=Y, 2=Z. + /// + /// `Idle` is a no-op by default. It receives noise only from explicitly + /// attached idle rates or from the base idle-noise model. #[must_use] pub fn rate_1q(&self, gate: GateType, pauli_idx: usize) -> f64 { - self.rates_1q - .get(&gate) - .map_or(self.base.p1 / 3.0, |r| r[pauli_idx]) + if let Some(rates) = self.rates_1q.get(&gate) { + return rates[pauli_idx]; + } + if gate == GateType::Idle { + if self.base.uses_dedicated_idle_noise() { + let probs = self.base.idle_pauli_probs(1.0); + return match pauli_idx { + 0 => probs.px, + 1 => probs.py, + 2 => probs.pz, + _ => 0.0, + }; + } + return 0.0; + } + self.base.p1 / 3.0 } /// Lookup 1Q Pauli rate for a gate on a specific qubit. Tries the diff --git a/crates/pecos-qec/tests/idle_noise_tests.rs b/crates/pecos-qec/tests/idle_noise_tests.rs index d462a3bd1..6eebe49d0 100644 --- a/crates/pecos-qec/tests/idle_noise_tests.rs +++ b/crates/pecos-qec/tests/idle_noise_tests.rs @@ -10,14 +10,14 @@ // or implied. See the License for the specific language governing permissions and limitations under // the License. -//! Integration tests for idle-gate noise. In QEC circuits, ancilla -//! qubits often sit idle while 2Q gates run on others. Before this test, -//! `GateType::Idle` locations were silently dropped from the DEM (they -//! fell through the default arm in `build()`). These tests verify idle -//! qubits now contribute per-qubit per-Pauli rates. +//! Integration tests for idle-gate noise. `GateType::Idle` is a no-op unless +//! noise is explicitly attached to idle locations via dedicated idle noise or +//! per-gate idle rates. use pecos_core::{QubitId, TimeUnits}; -use pecos_qec::fault_tolerance::dem_builder::{DemSamplerBuilder, NoiseConfig, PerGateTypeNoise}; +use pecos_qec::fault_tolerance::dem_builder::{ + DemBuilder, DemSamplerBuilder, NoiseConfig, PerGateTypeNoise, +}; use pecos_qec::fault_tolerance::propagator::DagFaultAnalyzer; use pecos_quantum::{DagCircuit, GateType}; @@ -66,9 +66,8 @@ fn idle_locations_contribute_mechanisms_when_rates_set() { #[test] fn idle_rates_absent_means_no_idle_contribution() { - // Config provides no Idle rates and uses zero base noise. DEM should - // have zero mechanisms: prep/measure are 0 and idle uses the - // per-gate-type default ([p1/3]), which is 0 here. + // Config provides no Idle rates and uses zero base noise. DEM should have + // zero mechanisms: prep/measure are 0 and idle is a no-op by default. let dag = build_idle_then_measure(3); let analyzer = DagFaultAnalyzer::new(&dag); let influence = analyzer.build_influence_map(); @@ -82,6 +81,43 @@ fn idle_rates_absent_means_no_idle_contribution() { assert_eq!(sim.num_mechanisms(), 0); } +#[test] +fn per_gate_base_p1_does_not_attach_to_idle() { + let dag = build_idle_then_measure(2); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let cfg = PerGateTypeNoise::from_base_noise(NoiseConfig::new(0.01, 0.0, 0.0, 0.0)); + let sim = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-2]}, {"id": 1, "records": [-1]}]"#) + .unwrap() + .build() + .unwrap(); + + assert_eq!(sim.num_mechanisms(), 0); +} + +#[test] +fn per_gate_base_idle_noise_attaches_to_idle() { + let dag = build_idle_then_measure(2); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let cfg = PerGateTypeNoise::from_base_noise(NoiseConfig::with_idle(0.01, 0.0, 0.0, 0.0, 0.002)); + let sim = DemSamplerBuilder::new(&influence) + .with_per_gate_noise(cfg) + .with_detectors_json(r#"[{"id": 0, "records": [-2]}, {"id": 1, "records": [-1]}]"#) + .unwrap() + .build() + .unwrap(); + + assert!( + sim.num_mechanisms() > 0, + "base p_idle in per-gate config should attach to idle locations", + ); +} + #[test] fn idle_noise_respects_per_qubit_override() { // q0 gets boosted idle rate; q1 gets zero. Expect exactly one @@ -107,10 +143,9 @@ fn idle_noise_respects_per_qubit_override() { } #[test] -fn idle_with_scalar_uniform_still_noisy() { - // Legacy uniform-depolarizing path: p1 = 0.01 applied uniformly. - // Idle locations should now ALSO pick up this rate (they used to - // be silent). Ensure the legacy path isn't regressed. +fn idle_with_scalar_p1_is_noop() { + // Ordinary p1 gate noise should not attach to Idle. Idle is a no-op unless + // idle noise is explicitly configured. let dag = build_idle_then_measure(2); let analyzer = DagFaultAnalyzer::new(&dag); let influence = analyzer.build_influence_map(); @@ -122,10 +157,57 @@ fn idle_with_scalar_uniform_still_noisy() { .build() .unwrap(); - // Before fix: zero mechanisms (idle ignored). After fix: idle on - // both qubits contributes. + assert_eq!(sim.num_mechanisms(), 0); +} + +#[test] +fn explicit_uniform_idle_noise_is_noisy() { + let dag = build_idle_then_measure(2); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let sim = DemSamplerBuilder::new(&influence) + .with_noise_config(NoiseConfig::with_idle(0.01, 0.0, 0.0, 0.0, 0.002)) + .with_detectors_json(r#"[{"id": 0, "records": [-2]}, {"id": 1, "records": [-1]}]"#) + .unwrap() + .build() + .unwrap(); + assert!( sim.num_mechanisms() > 0, - "scalar p1 path should propagate through idle locations too", + "explicit p_idle should produce idle-location mechanisms", + ); +} + +#[test] +fn dem_builder_scalar_p1_does_not_attach_to_idle() { + let dag = build_idle_then_measure(1); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let dem = DemBuilder::new(&influence) + .with_noise(0.01, 0.0, 0.0, 0.0) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + assert_eq!(dem.num_contributions(), 0); +} + +#[test] +fn dem_builder_explicit_idle_noise_is_noisy() { + let dag = build_idle_then_measure(1); + let analyzer = DagFaultAnalyzer::new(&dag); + let influence = analyzer.build_influence_map(); + + let dem = DemBuilder::new(&influence) + .with_noise_config(NoiseConfig::with_idle(0.01, 0.0, 0.0, 0.0, 0.002)) + .with_detectors_json(r#"[{"id": 0, "records": [-1]}]"#) + .unwrap() + .build(); + + assert!( + dem.num_contributions() > 0, + "explicit p_idle should produce idle-location DEM contributions", ); } diff --git a/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py b/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py index 4cbd54ef0..c66708667 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py +++ b/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py @@ -2215,6 +2215,9 @@ def generate_dem_from_tick_circuit( p2: float = 0.01, p_meas: float = 0.01, p_prep: float = 0.01, + p_idle: float | None = None, + t1: float | None = None, + t2: float | None = None, decompose_errors: bool = True, maximal_decomposition: bool = False, ) -> str: @@ -2242,6 +2245,10 @@ def generate_dem_from_tick_circuit( p2: Two-qubit depolarizing error rate p_meas: Measurement error rate p_prep: Initialization (prep) error rate + p_idle: Optional idle noise rate per explicit idle-gate time unit. + The caller is responsible for inserting idle gates where needed. + t1: Optional T1 relaxation time for explicit idle gates. + t2: Optional T2 dephasing time for explicit idle gates. decompose_errors: If True (default), decompose hyperedge errors into graphlike components using the `^` separator. Set to False to output raw hyperedges. Ignored if maximal_decomposition=True. @@ -2276,7 +2283,7 @@ def generate_dem_from_tick_circuit( # Build DEM using Rust DemBuilder builder = DemBuilder(influence_map) - builder.with_noise(p1, p2, p_meas, p_prep) + builder.with_noise(p1, p2, p_meas, p_prep, p_idle=p_idle, t1=t1, t2=t2) builder.with_num_measurements(num_measurements) builder.with_measurement_order(measurement_order) builder.with_detectors_json(detectors_json) diff --git a/python/quantum-pecos/src/pecos/qec/surface/decode.py b/python/quantum-pecos/src/pecos/qec/surface/decode.py index e7333e767..f4efd9522 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/decode.py +++ b/python/quantum-pecos/src/pecos/qec/surface/decode.py @@ -755,6 +755,21 @@ def _can_use_cached_surface_topology( return ancilla_budget is None +def _uses_dedicated_idle_noise( + *, + p_idle: float | None, + t1: float | None, + t2: float | None, +) -> bool: + """Return True when noise parameters require explicit idle locations.""" + return (p_idle is not None and p_idle > 0.0) or (t1 is not None and t2 is not None) + + +def _noise_uses_dedicated_idle_noise(noise: NoiseModel) -> bool: + """Return True when this noise model requires explicit idle locations.""" + return _uses_dedicated_idle_noise(p_idle=noise.p_idle, t1=noise.t1, t2=noise.t2) + + @cache def _cached_surface_native_topology( patch_key: tuple[int, int, str, bool], @@ -762,6 +777,7 @@ def _cached_surface_native_topology( basis: str, ancilla_budget: int | None, circuit_source: Literal["abstract", "traced_qis"], + include_idle_gates: bool, ) -> _CachedNativeSurfaceTopology: """Cache topology-only native analysis shared across noise parameters.""" import json @@ -777,11 +793,11 @@ def _cached_surface_native_topology( ancilla_budget=ancilla_budget, circuit_source=circuit_source, ) - # Insert idle gates so non-active qubits get noise in the after-only model. - # Note: the traced circuit has one gate per tick (fully serialized). - # Call tc.compact_ticks() before this to merge parallel gates into - # shared ticks if the hardware model supports parallel execution. - tc.fill_idle_gates() + if include_idle_gates: + # Insert idle gates only when the requested noise model includes a + # dedicated idle channel. Otherwise inserted idle gates receive ordinary + # one-qubit gate noise and change the explicit circuit-level DEM. + tc.fill_idle_gates() dag = tc.to_dag_circuit() analyzer = DagFaultAnalyzer(dag) @@ -841,12 +857,14 @@ def _cached_surface_native_dem_string( t2: float | None = None, ) -> str: """Cache native DEM strings across callers for one topology + noise tuple.""" + include_idle_gates = _uses_dedicated_idle_noise(p_idle=p_idle, t1=t1, t2=t2) topology = _cached_surface_native_topology( patch_key, num_rounds, basis, ancilla_budget, circuit_source, + include_idle_gates, ) return _dem_string_from_cached_surface_topology( topology, @@ -932,10 +950,8 @@ def _build_native_sampler_from_tick_circuit( from pecos.qec import DagFaultAnalyzer, DemSampler, ParsedDem from pecos.qec.surface.circuit_builder import generate_dem_from_tick_circuit - # Insert idle gates for qubits not active during each tick. - # This is critical: without idle gates, qubits sitting idle between - # operations get no noise in the after-only fault model. - tc.fill_idle_gates() + if _noise_uses_dedicated_idle_noise(noise): + tc.fill_idle_gates() dag = tc.to_dag_circuit() analyzer = DagFaultAnalyzer(dag) @@ -953,6 +969,9 @@ def _build_native_sampler_from_tick_circuit( p2=noise.p2, p_meas=noise.p_meas, p_prep=noise.p_prep, + p_idle=noise.p_idle, + t1=noise.t1, + t2=noise.t2, decompose_errors=True, ) sampler = ParsedDem.from_string(dem_str).to_dem_sampler() @@ -973,8 +992,8 @@ def _build_native_sampler_from_tick_circuit( ) sampling_model = "influence_dem" elif sampling_model == "from_circuit": - # Direct from_circuit path: uses DagCircuit annotations and - # handles idle noise automatically via NoiseConfig. + # Direct from_circuit path: uses DagCircuit annotations and any + # explicit idle locations inserted above for dedicated idle noise. sampler = DemSampler.from_circuit( dag, p1=noise.p1, @@ -1072,12 +1091,17 @@ def generate_circuit_level_dem_from_builder( ancilla_budget=ancilla_budget, circuit_source=circuit_source, ) + if _noise_uses_dedicated_idle_noise(noise): + tc.fill_idle_gates() return generate_dem_from_tick_circuit( tc, p1=noise.p1, p2=noise.p2, p_meas=noise.p_meas, p_prep=noise.p_prep, + p_idle=noise.p_idle, + t1=noise.t1, + t2=noise.t2, decompose_errors=decompose_errors, ) @@ -2627,6 +2651,7 @@ def build_native_sampler( basis, ancilla_budget, circuit_source, + _noise_uses_dedicated_idle_noise(noise), ) if sampling_model == "dem": dem_str = _cached_surface_native_dem_string( diff --git a/python/quantum-pecos/tests/qec/surface/test_surface_decoder.py b/python/quantum-pecos/tests/qec/surface/test_surface_decoder.py index dad4f92aa..c89112f6b 100644 --- a/python/quantum-pecos/tests/qec/surface/test_surface_decoder.py +++ b/python/quantum-pecos/tests/qec/surface/test_surface_decoder.py @@ -383,6 +383,49 @@ def test_native_circuit_level_dem_cache_respects_patch_geometry(self) -> None: assert cached_dem == expected_dem + def test_native_circuit_level_dem_cache_inserts_idle_gates_only_for_idle_noise(self) -> None: + """Shared native DEM caching should make idle locations an explicit noise choice.""" + from pecos.qec.surface.circuit_builder import generate_dem_from_tick_circuit, generate_tick_circuit_from_patch + from pecos.qec.surface.decode import generate_circuit_level_dem_from_builder + + patch = SurfacePatch.create(distance=3) + base_noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.01, p_prep=0.001) + base_params = { + "p1": base_noise.p1, + "p2": base_noise.p2, + "p_meas": base_noise.p_meas, + "p_prep": base_noise.p_prep, + "decompose_errors": False, + } + + tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="X") + expected_base_dem = generate_dem_from_tick_circuit(tc, **base_params) + cached_base_dem = generate_circuit_level_dem_from_builder( + patch, + num_rounds=2, + noise=base_noise, + basis="X", + ) + + idle_noise = NoiseModel(p1=0.001, p2=0.01, p_meas=0.01, p_prep=0.001, p_idle=0.002) + idle_tc = generate_tick_circuit_from_patch(patch, num_rounds=2, basis="X") + idle_tc.fill_idle_gates() + expected_idle_dem = generate_dem_from_tick_circuit( + idle_tc, + **base_params, + p_idle=idle_noise.p_idle, + ) + cached_idle_dem = generate_circuit_level_dem_from_builder( + patch, + num_rounds=2, + noise=idle_noise, + basis="X", + ) + + assert cached_base_dem == expected_base_dem + assert cached_idle_dem == expected_idle_dem + assert cached_idle_dem != cached_base_dem + def test_traced_qis_native_dem_and_sampler_build(self) -> None: """The traced-QIS circuit source should build DEMs and samplers end-to-end.""" from pecos.qec.surface import build_native_sampler From cd1373f15042fce27d50f2a3ac0d89c6d36703f6 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 16:00:14 -0600 Subject: [PATCH 095/125] Make doc tests runnable and harden checks --- .../pecos-decoder-core/src/decode_budget.rs | 17 ++++- crates/pecos-decoder-core/src/dem.rs | 60 +++++++++++++-- .../src/logical_algorithm.rs | 33 ++++++-- crates/pecos-decoder-core/src/pauli_frame.rs | 22 +++++- crates/pecos-foreign/src/conformance.rs | 11 ++- crates/pecos-foreign/src/gate_support.rs | 11 ++- .../fault_tolerance/dem_builder/builder.rs | 21 ++++-- .../fault_tolerance/dem_builder/sampler.rs | 17 ++++- .../src/fault_tolerance/influence_builder.rs | 12 ++- .../src/fault_tolerance/lookup_decoder.rs | 13 ++-- .../src/fault_tolerance/propagator/dag.rs | 39 ++++++++-- .../src/measurement_stress_test_utils.rs | 5 +- docs/user-guide/fault-catalog.md | 7 +- exp/pecos-lindblad/src/synthesis.rs | 19 +++++ exp/pecos-lindblad/tests/four_qubit_smoke.rs | 8 +- exp/pecos-neo/src/adapter.rs | 6 +- exp/pecos-stab-tn/src/stab_mps.rs | 7 +- .../tests/docs/rust_crate/Cargo.lock | 2 + .../tests/user_guide_fault_catalog.rs | 75 ++++++++++++++++++- scripts/docs/generate_doc_tests.py | 12 +++ 20 files changed, 338 insertions(+), 59 deletions(-) diff --git a/crates/pecos-decoder-core/src/decode_budget.rs b/crates/pecos-decoder-core/src/decode_budget.rs index b3bca9aa1..140b89582 100644 --- a/crates/pecos-decoder-core/src/decode_budget.rs +++ b/crates/pecos-decoder-core/src/decode_budget.rs @@ -18,10 +18,19 @@ //! //! # Example //! -//! ```ignore -//! let budget = DecodeBudget::neutral_atom(distance); -//! let strategy = CommittedOsdStrategy::new(osd, budget); -//! let decoder = LogicalCircuitDecoder::new(descriptor, strategy); +//! ``` +//! use std::time::Duration; +//! +//! use pecos_decoder_core::decode_budget::{DecodeBudget, DetectorRegion}; +//! +//! let distance = 7; +//! let budget = DecodeBudget::from_reaction_time(Duration::from_millis(1), distance); +//! assert!(budget.is_windowed()); +//! assert_eq!(budget.code_distance, distance); +//! +//! let first_round = DetectorRegion { start: 0, end: distance * distance }; +//! assert!(first_round.contains(0)); +//! assert!(!first_round.is_empty()); //! ``` use crate::errors::DecoderError; diff --git a/crates/pecos-decoder-core/src/dem.rs b/crates/pecos-decoder-core/src/dem.rs index e497d7dea..324a21e50 100644 --- a/crates/pecos-decoder-core/src/dem.rs +++ b/crates/pecos-decoder-core/src/dem.rs @@ -617,13 +617,63 @@ impl DemMatchingGraph { /// /// # Example /// -/// ```ignore -/// use pecos_decoder_core::dem::{DemCheckMatrix, CheckMatrixObservableDecoder}; +/// ``` +/// use ndarray::ArrayView1; +/// +/// use pecos_decoder_core::{ +/// CheckMatrixObservableDecoder, Decoder, DecoderError, DecodingResultTrait, DemCheckMatrix, +/// ObservableDecoder, +/// }; +/// +/// struct CorrectionResult { +/// correction: Vec, +/// } +/// +/// impl DecodingResultTrait for CorrectionResult { +/// fn is_successful(&self) -> bool { +/// true +/// } +/// +/// fn correction(&self) -> &[u8] { +/// &self.correction +/// } +/// } +/// +/// struct FirstMechanismDecoder { +/// checks: usize, +/// bits: usize, +/// } /// -/// let dcm = DemCheckMatrix::from_dem_str(dem_str)?; -/// let inner_decoder = /* create BP+OSD from dcm.check_matrix */; +/// impl Decoder for FirstMechanismDecoder { +/// type Result = CorrectionResult; +/// type Error = DecoderError; +/// +/// fn decode(&mut self, input: &ArrayView1) -> Result { +/// assert_eq!(input.len(), self.checks); +/// let mut correction = vec![0; self.bits]; +/// correction[0] = 1; +/// Ok(CorrectionResult { correction }) +/// } +/// +/// fn check_count(&self) -> usize { +/// self.checks +/// } +/// +/// fn bit_count(&self) -> usize { +/// self.bits +/// } +/// } +/// +/// let dem_str = "error(0.01) D0 L0\nerror(0.02) D0"; +/// let dcm = DemCheckMatrix::from_dem_str(dem_str).unwrap(); +/// let inner_decoder = FirstMechanismDecoder { +/// checks: dcm.num_detectors, +/// bits: dcm.num_mechanisms, +/// }; /// let mut decoder = CheckMatrixObservableDecoder::new(inner_decoder, dcm); -/// let mask = decoder.decode_to_observables(&syndrome)?; +/// +/// let mask = decoder.decode_to_observables(&[1]).unwrap(); +/// assert_eq!(mask, 0b1); /// ``` pub struct CheckMatrixObservableDecoder { /// The inner check-matrix decoder. diff --git a/crates/pecos-decoder-core/src/logical_algorithm.rs b/crates/pecos-decoder-core/src/logical_algorithm.rs index d3587c026..cb97a7113 100644 --- a/crates/pecos-decoder-core/src/logical_algorithm.rs +++ b/crates/pecos-decoder-core/src/logical_algorithm.rs @@ -222,16 +222,39 @@ impl ObservableDecoder for LogicalAlgorithmDecoder { /// /// # Usage /// -/// ```ignore -/// let mut stream = StreamingLogicalDecoder::new(decoder, round_to_det_map); +/// ``` +/// use pecos_decoder_core::{DecoderError, ObservableDecoder}; +/// use pecos_decoder_core::logical_algorithm::{ +/// AlgorithmDescriptor, LogicalAlgorithmDecoder, SegmentDescriptor, StreamingLogicalDecoder, +/// }; +/// +/// struct AnyDetectionDecoder; +/// +/// impl ObservableDecoder for AnyDetectionDecoder { +/// fn decode_to_observables(&mut self, syndrome: &[u8]) -> Result { +/// Ok(u64::from(syndrome.iter().any(|&bit| bit != 0))) +/// } +/// } +/// +/// let descriptor = AlgorithmDescriptor { +/// segments: vec![SegmentDescriptor { +/// num_detectors: 2, +/// num_observables: 1, +/// }], +/// boundary_gates: vec![], +/// num_observables: 1, +/// }; +/// let decoder = LogicalAlgorithmDecoder::new(Box::new(AnyDetectionDecoder), descriptor); +/// let mut stream = StreamingLogicalDecoder::new(decoder); /// /// // Feed syndrome round by round -/// for (round, detectors) in syndrome_stream { -/// stream.feed_round(&detectors); +/// for sparse_round in [vec![(0, 1)], vec![(1, 0)]] { +/// stream.feed_sparse(&sparse_round); /// } /// /// // Decode at the end -/// let obs = stream.flush()?; +/// let obs = stream.flush().unwrap(); +/// assert_eq!(obs, 1); /// ``` pub struct StreamingLogicalDecoder { /// The underlying batch decoder (full-circuit OSD). diff --git a/crates/pecos-decoder-core/src/pauli_frame.rs b/crates/pecos-decoder-core/src/pauli_frame.rs index a2172b632..c5182c999 100644 --- a/crates/pecos-decoder-core/src/pauli_frame.rs +++ b/crates/pecos-decoder-core/src/pauli_frame.rs @@ -19,17 +19,31 @@ //! //! # Example //! -//! ```ignore -//! let mut frame = PauliFrameAccumulator::new(decoder); +//! ``` +//! use pecos_decoder_core::{DecoderError, ObservableDecoder}; +//! use pecos_decoder_core::pauli_frame::PauliFrameAccumulator; +//! +//! struct FixedDecoder(u64); +//! +//! impl ObservableDecoder for FixedDecoder { +//! fn decode_to_observables(&mut self, _syndrome: &[u8]) -> Result { +//! Ok(self.0) +//! } +//! } +//! +//! let mut frame = PauliFrameAccumulator::new(Box::new(FixedDecoder(0b01))); //! //! // QEC cycles -//! for syndrome in syndrome_stream { -//! frame.decode_cycle(&syndrome)?; +//! for syndrome in [&[1, 0][..], &[0, 1][..]] { +//! frame.decode_cycle(syndrome).unwrap(); //! } +//! assert_eq!(frame.current_frame(), 0b00); //! //! // At logical measurement: consume frame //! let correction = frame.consume_frame(); +//! let raw_measurement = 1; //! let logical_result = raw_measurement ^ (correction & 1); +//! assert_eq!(logical_result, 1); //! ``` use crate::ObservableDecoder; diff --git a/crates/pecos-foreign/src/conformance.rs b/crates/pecos-foreign/src/conformance.rs index 103d80e45..e2387f279 100644 --- a/crates/pecos-foreign/src/conformance.rs +++ b/crates/pecos-foreign/src/conformance.rs @@ -15,9 +15,14 @@ //! //! # Usage from Rust //! -//! ```rust,ignore -//! let results = run_conformance_tests(&mut foreign_sim); -//! assert!(results.all_passed()); +//! ```rust,no_run +//! use pecos_foreign::ForeignSimulator; +//! use pecos_foreign::conformance::run_conformance_tests; +//! +//! fn check_foreign_simulator(mut foreign_sim: ForeignSimulator) { +//! let results = run_conformance_tests(&mut foreign_sim); +//! assert!(results.all_passed()); +//! } //! ``` use crate::simulator::{ForeignSimulator, ForeignSimulatorVTable}; diff --git a/crates/pecos-foreign/src/gate_support.rs b/crates/pecos-foreign/src/gate_support.rs index 31e232b3a..c42416c6b 100644 --- a/crates/pecos-foreign/src/gate_support.rs +++ b/crates/pecos-foreign/src/gate_support.rs @@ -11,9 +11,14 @@ //! //! # Example //! -//! ```rust,ignore -//! let sim = ForeignSimulator::new(handle, vtable); -//! let runner = configure_runner_for_foreign(&sim); +//! ```rust,no_run +//! use pecos_foreign::ForeignSimulator; +//! use pecos_foreign::gate_support::configure_runner_for_foreign; +//! +//! fn configure_foreign_runner(sim: &ForeignSimulator) { +//! let runner = configure_runner_for_foreign(sim); +//! let _ = runner; +//! } //! // runner will decompose unsupported gates into {SZ, H, CX, MZ, RX?, RZ?, RZZ?} //! ``` diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs index 8722a27a6..5026fb7af 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs @@ -54,19 +54,25 @@ struct ParsedObservable { /// /// For most use cases, use the one-liner: /// -/// ```ignore +/// ``` /// use pecos_qec::fault_tolerance::dem_builder::DemBuilder; +/// use pecos_quantum::DagCircuit; /// /// // Build DEM from circuit + noise (reads detectors from circuit metadata) +/// let dag = DagCircuit::new(); /// let dem = DemBuilder::from_circuit(&dag, 0.001, 0.01, 0.001, 0.001); -/// println!("{}", dem.to_string()); +/// assert_eq!(dem.num_detectors(), 0); /// ``` /// /// Also works with `TickCircuit`: /// -/// ```ignore -/// # use pecos_qec::fault_tolerance::dem_builder::DemBuilder; +/// ``` +/// use pecos_qec::fault_tolerance::dem_builder::DemBuilder; +/// use pecos_quantum::TickCircuit; +/// +/// let tc = TickCircuit::new(); /// let dem = DemBuilder::from_tick_circuit(&tc, 0.001, 0.01, 0.001, 0.001); +/// assert_eq!(dem.num_detectors(), 0); /// ``` /// /// # Advanced API @@ -111,10 +117,13 @@ impl<'a> DemBuilder<'a> { /// One-liner for the common case. Reads detector/DEM output definitions /// from circuit metadata (`"detectors"`, `"observables"` attributes). /// - /// ```ignore + /// ``` /// use pecos_qec::fault_tolerance::dem_builder::DemBuilder; + /// use pecos_quantum::DagCircuit; + /// + /// let dag = DagCircuit::new(); /// let dem = DemBuilder::from_circuit(&dag, 0.001, 0.01, 0.001, 0.001); - /// println!("{}", dem.to_string()); + /// assert_eq!(dem.num_detectors(), 0); /// ``` /// Build a `DetectorErrorModel` directly from a `DagCircuit` and noise. /// diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs index 63d5981f8..b99f75136 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs @@ -327,12 +327,21 @@ impl DemSampler { /// /// # Example /// - /// ```ignore - /// let mut dag = DagCircuit::new(); - /// // ... build circuit, add detectors/observables ... + /// ``` + /// use rand::SeedableRng; + /// use rand::rngs::StdRng; + /// + /// use pecos_qec::fault_tolerance::dem_builder::{DemSampler, NoiseConfig}; + /// use pecos_quantum::DagCircuit; + /// + /// let dag = DagCircuit::new(); /// let noise = NoiseConfig::uniform(0.01); - /// let sampler = DemSampler::from_circuit(&dag, &noise)?; + /// let sampler = DemSampler::from_circuit(&dag, &noise).unwrap(); + /// + /// let mut rng = StdRng::seed_from_u64(123); /// let (det, obs) = sampler.sample(&mut rng); + /// assert!(det.is_empty()); + /// assert!(obs.is_empty()); /// ``` /// Build a sampler from a `TickCircuit` and noise parameters. /// diff --git a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs index 6c9bb5f07..00e35c5aa 100644 --- a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs @@ -142,9 +142,17 @@ impl<'a> InfluenceBuilder<'a> { /// /// # Example /// - /// ```ignore + /// ``` /// // Check if Y = X_0 * Z_1 * Z_2 flips - /// builder.with_tracked_operator(PauliString::from_paulis(vec![(0, 1), (1, 3), (2, 3)])) + /// use pecos_core::{Pauli, PauliString}; + /// use pecos_qec::fault_tolerance::InfluenceBuilder; + /// use pecos_quantum::DagCircuit; + /// + /// let dag = DagCircuit::new(); + /// let builder = InfluenceBuilder::new(&dag).with_tracked_operator( + /// PauliString::from_paulis(&[Pauli::X, Pauli::Z, Pauli::Z]), + /// ); + /// let _map = builder.build(); /// ``` #[must_use] pub fn with_tracked_operator(mut self, pauli: PauliString) -> Self { diff --git a/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs b/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs index fa181284a..0ad232d1d 100644 --- a/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs +++ b/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs @@ -18,17 +18,18 @@ //! //! # Example //! -//! ```ignore +//! ``` //! use pecos_qec::fault_tolerance::lookup_decoder::LookupDecoder; +//! use pecos_qec::fault_tolerance::dem_builder::NoiseConfig; +//! use pecos_qec::fault_tolerance::propagator::dag::DagFaultInfluenceMap; //! -//! let map = InfluenceBuilder::new(&dag) -//! .with_circuit_annotations(&dag) -//! .build(); +//! let map = DagFaultInfluenceMap::with_capacity(0); //! let noise = NoiseConfig::uniform(0.001); //! //! let decoder = LookupDecoder::build(&map, &noise, 3); -//! let result = decoder.decode(&[0, 2]); // syndrome: detectors 0 and 2 fired -//! println!("corrections: {:?}", result.corrections); +//! let result = decoder.decode(&[]); +//! assert!(result.known_syndrome); +//! assert!(result.corrections.is_empty()); //! ``` use super::dem_builder::NoiseConfig; diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs b/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs index 454f5d140..6551a7326 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs @@ -992,9 +992,14 @@ impl DemOutputMetadata { /// compose via XOR (symmetric difference) for multi-qubit Pauli events. /// /// Borrows the influence map so you can query events directly: -/// ```ignore +/// ``` +/// use pecos_qec::fault_tolerance::propagator::dag::DagFaultInfluenceMap; +/// +/// let map = DagFaultInfluenceMap::with_capacity(0); /// for loc in map.gate_fault_locations() { -/// for event in loc.events() { ... } +/// for event in loc.events() { +/// println!("{}: dets={:?}", event.pauli, event.detectors); +/// } /// } /// ``` pub struct GateFaultLocation<'a> { @@ -1034,9 +1039,25 @@ impl FaultEffect { /// - Detectors, `dem_outputs`, and measurements are XOR'd (symmetric difference) /// /// This is the building block for weight-w fault analysis: - /// ```ignore + /// ``` + /// use pecos_core::PauliString; + /// use pecos_qec::fault_tolerance::propagator::dag::FaultEffect; + /// + /// let effect_a = FaultEffect { + /// pauli: PauliString::x(0), + /// detectors: vec![0], + /// dem_outputs: vec![], + /// measurements: vec![], + /// }; + /// let effect_b = FaultEffect { + /// pauli: PauliString::z(1), + /// detectors: vec![0, 1], + /// dem_outputs: vec![0], + /// measurements: vec![], + /// }; /// let w2 = effect_a.compose(&effect_b); - /// let w3 = w2.compose(&effect_c); + /// assert_eq!(w2.detectors, vec![1]); + /// assert_eq!(w2.dem_outputs, vec![0]); /// ``` #[must_use] pub fn compose(&self, other: &Self) -> Self { @@ -1367,7 +1388,10 @@ impl DagFaultInfluenceMap { /// Each returned [`GateFaultLocation`] represents a gate at a specific /// timing (before/after) and supports querying multi-qubit Pauli events. /// - /// ```ignore + /// ``` + /// use pecos_qec::fault_tolerance::propagator::dag::DagFaultInfluenceMap; + /// + /// let map = DagFaultInfluenceMap::with_capacity(0); /// for loc in map.gate_fault_locations() { /// for event in loc.events() { /// println!("{}: dets={:?} dem_outputs={:?}", event.pauli, event.detectors, event.dem_outputs); @@ -1435,7 +1459,10 @@ impl DagFaultInfluenceMap { /// /// Uses a callback to avoid allocating a potentially huge result vec. /// - /// ```ignore + /// ``` + /// use pecos_qec::fault_tolerance::propagator::dag::DagFaultInfluenceMap; + /// + /// let map = DagFaultInfluenceMap::with_capacity(0); /// // Find all undetectable weight-2 errors /// map.for_each_fault_combo(2, |combo| { /// if !combo.effect.dem_outputs.is_empty() && combo.effect.detectors.is_empty() { diff --git a/crates/pecos-simulators/src/measurement_stress_test_utils.rs b/crates/pecos-simulators/src/measurement_stress_test_utils.rs index 787c09a0d..336128405 100644 --- a/crates/pecos-simulators/src/measurement_stress_test_utils.rs +++ b/crates/pecos-simulators/src/measurement_stress_test_utils.rs @@ -268,8 +268,9 @@ pub fn run_measurement_stress_tests(sim: &mut S) { /// Generate a test that runs the measurement stress suite on a simulator type. /// /// Usage: -/// ```ignore -/// use pecos_simulators::measurement_stress_test_suite; +/// ``` +/// use pecos_simulators::{StabVec, measurement_stress_test_suite}; +/// /// measurement_stress_test_suite!(StabVec, 4); /// ``` #[macro_export] diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index fcc279315..522619c5e 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -4,7 +4,7 @@ If you have a surface code and want to simulate noisy measurements: - + ```python from pecos.qec.surface import SurfacePatch from pecos.qec.surface.decode import _build_surface_tick_circuit_for_native_model @@ -28,7 +28,7 @@ print(f"{len(result)} shots, {len(result[0])} measurements each") If you want to inspect what faults are possible in that circuit: - + ```python from pecos_rslib_exp import fault_catalog @@ -379,6 +379,7 @@ for event in catalog.fault_configurations(1): The Rust API lives in `pecos-qec`: + ```rust use pecos_qec::fault_tolerance::fault_sampler::{ FaultCatalog, StochasticNoiseParams, @@ -417,6 +418,7 @@ catalog.with_noise(&noise); Iterate locations and alternatives: + ```rust for loc in &catalog.locations { println!( @@ -443,6 +445,7 @@ for loc in &catalog.locations { Iterate configurations: + ```rust for event in catalog.fault_configurations(2) { println!( diff --git a/exp/pecos-lindblad/src/synthesis.rs b/exp/pecos-lindblad/src/synthesis.rs index 7eeb7f7b2..e0f0cdb03 100644 --- a/exp/pecos-lindblad/src/synthesis.rs +++ b/exp/pecos-lindblad/src/synthesis.rs @@ -279,6 +279,15 @@ pub fn synthesize_numerical(gate: &Gate, n_steps: usize) -> PauliLindbladModel { ); let n = gate.num_qubits; let paulis = PauliString::enumerate_nonidentity(n); + if is_zero_matrix(&gate.ideal.hamiltonian) { + let tau = gate.tau_g; + let alphas: Vec = paulis + .iter() + .map(|p| constant_alpha_pauli_string(&gate.noise, p) * tau) + .collect(); + return model_from_alphas_walsh(paulis, alphas, n); + } + let alphas: Vec = paulis .iter() .map(|p| integrated_alpha(gate, p, n_steps)) @@ -295,6 +304,16 @@ fn constant_alpha(noise: &Lindbladian, p: Pauli1) -> f64 { -inner.re / d as f64 } +/// `alpha_b = -Tr(P_b L(P_b)) / d` for a time-independent Lindbladian and +/// arbitrary-qubit Pauli string. Units: 1/time. +fn constant_alpha_pauli_string(noise: &Lindbladian, p: &PauliString) -> f64 { + let d = noise.d; + let p_mat = matrix::pauli_string_mat(p); + let l_p = noise.apply(&p_mat); + let inner = matrix::trace(&matrix::matmul(&p_mat, &l_p, d), d); + -inner.re / d as f64 +} + /// Integrated `alpha_b * tau_g = -Tr(P_b * Omega_1(P_b)) / d` via Simpson's /// rule on `[0, tau_g]`. Works for any `n_qubits`. fn integrated_alpha(gate: &Gate, p: &PauliString, n_steps: usize) -> f64 { diff --git a/exp/pecos-lindblad/tests/four_qubit_smoke.rs b/exp/pecos-lindblad/tests/four_qubit_smoke.rs index 121380595..a9487bc74 100644 --- a/exp/pecos-lindblad/tests/four_qubit_smoke.rs +++ b/exp/pecos-lindblad/tests/four_qubit_smoke.rs @@ -22,8 +22,8 @@ use num_complex::Complex64; use pecos_lindblad::matrix::{self, Matrix}; use pecos_lindblad::{ - DEFAULT_N_STEPS, Gate, Lindbladian, Pauli1, PauliString, synthesize_exact_unitary, - synthesize_numerical, + synthesize_exact_unitary, synthesize_numerical, Gate, Lindbladian, Pauli1, PauliString, + DEFAULT_N_STEPS, }; fn kron_all(ops: &[&Matrix]) -> Matrix { @@ -59,6 +59,7 @@ fn four_qubit_identity_ad_on_one_qubit() { let gate = Gate::identity(4, noise, tau_g); let pl = synthesize_numerical(&gate, DEFAULT_N_STEPS); + let pl_coarse = synthesize_numerical(&gate, 2); // Expected non-zero rates: lambda_{q1=X}, lambda_{q1=Y}, lambda_{q1=Z} // on qubit 1 (index 1 from left in "qqqq" string). @@ -68,6 +69,9 @@ fn four_qubit_identity_ad_on_one_qubit() { assert_abs_diff_eq!(rate("IXII"), beta_down * tau_g / 4.0, epsilon = 1e-10); assert_abs_diff_eq!(rate("IYII"), beta_down * tau_g / 4.0, epsilon = 1e-10); assert_abs_diff_eq!(rate("IZII"), beta_phi * tau_g / 2.0, epsilon = 1e-10); + for ps in PauliString::enumerate_nonidentity(4) { + assert_abs_diff_eq!(pl.rate(&ps), pl_coarse.rate(&ps), epsilon = 1e-14); + } // All other 252 non-identity 4Q Paulis should be zero. for ps in PauliString::enumerate_nonidentity(4) { diff --git a/exp/pecos-neo/src/adapter.rs b/exp/pecos-neo/src/adapter.rs index 8dc2afcfb..51d7a3cee 100644 --- a/exp/pecos-neo/src/adapter.rs +++ b/exp/pecos-neo/src/adapter.rs @@ -29,8 +29,9 @@ //! //! ## Example //! -#![cfg_attr(feature = "engines-adapter", doc = "```no_run")] -#![cfg_attr(not(feature = "engines-adapter"), doc = "```ignore")] +//! ```rust,no_run +//! #[cfg(feature = "engines-adapter")] +//! fn example() { //! use std::str::FromStr; //! use pecos_neo::adapter::ClassicalEngineAdapter; //! use pecos_neo::prelude::*; @@ -61,6 +62,7 @@ //! .with_noise(noise); //! //! let result = runner.run_shot(&mut program); +//! } //! ``` use crate::command::{CommandQueue, GateCommand, GateType as NeoGateType}; diff --git a/exp/pecos-stab-tn/src/stab_mps.rs b/exp/pecos-stab-tn/src/stab_mps.rs index 21d9154c3..c6a082852 100644 --- a/exp/pecos-stab-tn/src/stab_mps.rs +++ b/exp/pecos-stab-tn/src/stab_mps.rs @@ -338,8 +338,11 @@ impl StabMpsBuilder { /// for adversarial T-heavy subcircuits before truncation hits the cap. /// /// Override any of these with subsequent builder calls: - /// ```ignore - /// StabMps::builder(n).for_qec().max_bond_dim(64).build() + /// ``` + /// use pecos_stab_tn::stab_mps::StabMps; + /// + /// let sim = StabMps::builder(4).for_qec().max_bond_dim(64).build(); + /// assert_eq!(sim.num_qubits(), 4); /// ``` #[must_use] pub fn for_qec(self) -> Self { diff --git a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock index 913ec3734..436a2117b 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock +++ b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock @@ -2992,6 +2992,7 @@ dependencies = [ "num-complex", "pecos-core", "pecos-num", + "pecos-random", "smallvec", "tket", ] @@ -3010,6 +3011,7 @@ dependencies = [ name = "pecos-simulators" version = "0.2.0-dev.0" dependencies = [ + "nalgebra", "num-complex", "pecos-core", "pecos-quantum", diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_catalog.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_catalog.rs index 18e97a7db..4864f605b 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_catalog.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_catalog.rs @@ -5,7 +5,7 @@ #[test] -fn test_user_guide_fault_catalog_rust_1() { +fn test_user_guide_fault_catalog_rust_1() -> Result<(), Box> { use pecos_quantum::{Attribute, TickCircuit}; use pecos_qec::fault_tolerance::fault_sampler::{ FaultCatalog, StochasticNoiseParams, @@ -38,4 +38,77 @@ FaultCatalog, StochasticNoiseParams, // Or one-shot convenience: // let catalog = build_fault_catalog(&circuit, &noise).unwrap(); + + for loc in &catalog.locations { + println!( + "tick={} gate={:?} channel={:?} p={} k={}", + loc.tick, + loc.gate_type, + loc.channel, + loc.channel_probability, + loc.num_alternatives + ); + + for fault in &loc.faults { + println!( + " {:?} dets={:?} obs={:?} tracked={:?} p_alt={}", + fault.kind, + fault.affected_detectors, + fault.affected_observables, + fault.affected_tracked_ops, + fault.absolute_probability + ); + } + } + Ok(()) +} + + + +#[test] +fn test_user_guide_fault_catalog_rust_2() -> Result<(), Box> { + use pecos_quantum::{Attribute, TickCircuit}; + use pecos_qec::fault_tolerance::fault_sampler::{ +FaultCatalog, StochasticNoiseParams, +}; + let mut circuit = TickCircuit::new(); + circuit.tick().h(&[0]); + circuit.tick().mz(&[0]); + + circuit.set_meta("num_measurements", Attribute::String("1".into())); + circuit.set_meta( + "detectors", + Attribute::String(r#"[{"records":[-1]}]"#.into()), + ); + circuit.set_meta( + "observables", + Attribute::String(r#"[{"records":[-1]}]"#.into()), + ); + + // Structural catalog (no noise): + let mut catalog = FaultCatalog::from_circuit(&circuit).unwrap(); + + // Parameterize: + let noise = StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }; + catalog.with_noise(&noise); + + // Or one-shot convenience: + // let catalog = build_fault_catalog(&circuit, &noise).unwrap(); + + for event in catalog.fault_configurations(2) { + println!( + "locations={:?} alternatives={:?} dets={:?} obs={:?} p={}", + event.location_indices, + event.alternative_indices, + event.affected_detectors, + event.affected_observables, + event.configuration_probability + ); + } + Ok(()) } diff --git a/scripts/docs/generate_doc_tests.py b/scripts/docs/generate_doc_tests.py index 457c4ac99..5503db0e2 100755 --- a/scripts/docs/generate_doc_tests.py +++ b/scripts/docs/generate_doc_tests.py @@ -24,6 +24,7 @@ - Skip if CUDA Rust bindings not available - Expect error matching regex pattern - Expect stdout to contain text + - Skip if Python module is unavailable - Name the test function - Add @pytest.mark.slow - Continue from previous block's state @@ -71,6 +72,7 @@ class CodeBlock: expect_output: str | None = None expect_output_block: str | None = None expect_output_mode: str = "exact" # "exact" or "ellipsis" + required_modules: list[str] = field(default_factory=list) test_name: str | None = None marks: list[str] = field(default_factory=list) is_continuation: bool = False @@ -200,6 +202,7 @@ def _parse_marker_comment(comment: str) -> dict: "expect_output": None, "expect_output_block": False, "expect_output_mode": "exact", + "required_modules": [], "test_name": None, "marks": [], "is_continuation": False, @@ -255,6 +258,12 @@ def _parse_marker_comment(comment: str) -> dict: if match: result["expect_output"] = match.group(1).strip() + # Check for required Python modules + if "requires-module" in comment_lower: + match = re.search(r"requires-module:\s*(.+?)\s*-->", comment, re.IGNORECASE) + if match: + result["required_modules"] = [module.strip() for module in match.group(1).split(",") if module.strip()] + # Check for test-name match = re.search(r"test-name:\s*(\w+)", comment, re.IGNORECASE) if match: @@ -420,6 +429,7 @@ def extract_code_blocks(file_path: Path, language: str = "python") -> list[CodeB expect_output=attrs["expect_output"], expect_output_block=output_block_text, expect_output_mode=output_mode, + required_modules=attrs["required_modules"], test_name=attrs["test_name"], marks=attrs["marks"], is_continuation=attrs["is_continuation"], @@ -469,6 +479,8 @@ def generate_test_function(block: CodeBlock, file_stem: str) -> str: # Docstring with source file and line number for easy navigation lines.append(f' """Test from {block.source_file}:{block.line_number}."""') + lines.extend(f' pytest.importorskip("{module}")' for module in block.required_modules) + # Generate function body based on test type and language if block.language == "rust": if block.expect_error: From 0a22ebf368b28e38e63757ea72bcc5298c8e3ae2 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 16:42:26 -0600 Subject: [PATCH 096/125] Polish PECOS concepts and PauliString ergonomics --- README.md | 1 + docs/README.md | 1 + docs/user-guide/fault-catalog.md | 7 +- docs/user-guide/getting-started.md | 1 + docs/user-guide/noise-model-builders.md | 11 ++ docs/user-guide/pecos-concepts.md | 141 ++++++++++++++++++ docs/user-guide/python-pauli-qec.md | 58 ++++--- docs/user-guide/quantum-operator-algebra.md | 17 ++- docs/user-guide/stabilizer-codes.md | 8 +- mkdocs.yml | 1 + python/pecos-rslib/pecos_rslib.pyi | 37 ++++- python/pecos-rslib/src/pauli_bindings.rs | 70 +++++---- .../src/pecos/quantum/__init__.py | 53 ++++--- .../tests/user_guide_pecos_concepts.rs | 25 ++++ .../user_guide_quantum_operator_algebra.rs | 13 +- .../tests/pecos/test_pauli_string_bindings.py | 51 +++++++ 16 files changed, 417 insertions(+), 78 deletions(-) create mode 100644 docs/user-guide/pecos-concepts.md create mode 100644 python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_pecos_concepts.rs create mode 100644 python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py diff --git a/README.md b/README.md index a1fa04841..d77865ba2 100644 --- a/README.md +++ b/README.md @@ -82,6 +82,7 @@ For OpenQASM, PHIR, or other formats, see the [documentation](#documentation). F For tutorials, API reference, and advanced features: - [Getting Started Guide](docs/user-guide/getting-started.md) — Installation, first simulation, next steps +- [PECOS Concepts](docs/user-guide/pecos-concepts.md) — Detectors, observables, tracked operators, gates, and noise - [Simulators Guide](docs/user-guide/simulators.md) — Choosing the right backend - [Noise Model Builders](docs/user-guide/noise-model-builders.md) — Adding realistic noise - [Decoders Guide](docs/user-guide/decoders.md) — Quantum error correction decoding diff --git a/docs/README.md b/docs/README.md index fede603fb..c6abac082 100644 --- a/docs/README.md +++ b/docs/README.md @@ -115,6 +115,7 @@ PECOS is available in multiple languages: This documentation is organized to help you get the most out of PECOS: - **[User Guide](user-guide/getting-started.md)**: Tutorials and guides for using PECOS +- **[PECOS Concepts](user-guide/pecos-concepts.md)**: Core terminology for detectors, observables, tracked operators, gates, and noise - **[Concepts](concepts/index.md)**: Physics, math, and algorithms behind the simulators - **API Reference**: Detailed API documentation - [Python API](https://quantum-pecos.readthedocs.io/en/latest/) diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index 522619c5e..acae9458d 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -73,7 +73,8 @@ noise model. Use this for sampling, decoding, and probability-weighted queries. ```python -from pecos.quantum import PauliString, TickCircuit +from pecos import Z +from pecos.quantum import TickCircuit from pecos_rslib_exp import depolarizing, fault_catalog circuit = TickCircuit() @@ -494,6 +495,8 @@ D0 flipped by None at MZ([0]) Tracked operators are Pauli operators that the catalog monitors for anticommutation with fault events. Unlike observables, they have no measurement records -- they are detected by forward Pauli propagation. +See [PECOS Concepts](pecos-concepts.md) for the full detector, observable, +and tracked-operator distinction. Add tracked operators to a circuit via `tracked_operator`: @@ -505,7 +508,7 @@ tc2.set_meta("num_measurements", "0") tc2.set_meta("detectors", "[]") tc2.set_meta("observables", "[]") # Track Z on qubit 0 -- X and Y faults after H anticommute with Z -tc2.tracked_operator(PauliString.from_str("Z"), label="track_Z0") +tc2.tracked_operator(Z(0), label="track_Z0") cat2 = fault_catalog(tc2, p1=0.01, p2=0.0, p_meas=0.0, p_prep=0.0) for loc in cat2: diff --git a/docs/user-guide/getting-started.md b/docs/user-guide/getting-started.md index 0997eebe3..11d6264cb 100644 --- a/docs/user-guide/getting-started.md +++ b/docs/user-guide/getting-started.md @@ -167,6 +167,7 @@ The Python example uses a state vector simulator, which supports all quantum gat ## Next Steps - **[HUGR & Guppy Simulation](hugr-simulation.md)**: Measurement-based control flow and advanced Guppy features +- **[PECOS Concepts](pecos-concepts.md)**: Detectors, observables, tracked operators, gates, channels, and fault locations - **[QASM Simulation](qasm-simulation.md)**: Full QASM simulation API for existing OpenQASM code - **[Simulators](simulators.md)**: Choose the right simulation backend - **[Noise Model Builders](noise-model-builders.md)**: Add realistic noise to your simulations diff --git a/docs/user-guide/noise-model-builders.md b/docs/user-guide/noise-model-builders.md index ebe0a1050..02eaf751b 100644 --- a/docs/user-guide/noise-model-builders.md +++ b/docs/user-guide/noise-model-builders.md @@ -131,6 +131,17 @@ noise = ( ) ``` +### Idle Locations + +`Idle` gates are timing markers by default. They do not silently inherit +single-qubit gate noise from `p1` or `with_p1_probability(...)`. + +This is intentional: adding an idle location changes circuit timing, while +adding idle noise changes the physical noise model. To model idle decoherence, +use an API that explicitly attaches idle noise or an explicit channel to idle +locations. This keeps scheduling changes from accidentally changing the noise +model. + ## Common Noise Model Examples ### Basic Depolarizing Noise diff --git a/docs/user-guide/pecos-concepts.md b/docs/user-guide/pecos-concepts.md new file mode 100644 index 000000000..0db073949 --- /dev/null +++ b/docs/user-guide/pecos-concepts.md @@ -0,0 +1,141 @@ +# PECOS Concepts + +PECOS keeps a few related QEC concepts separate because they answer different +questions. The implementation can share propagation machinery underneath, but +the public API should make the distinction clear. + +## Quick Map + +| Concept | Meaning | Typical source | Decoder role | +|---|---|---|---| +| Detector | A parity check on measurement records | Measurement record metadata | Syndrome bit | +| Observable | A measured logical or experiment output | Measurement record metadata | Logical class decoded from the syndrome | +| Tracked operator | A Pauli operator inserted as a non-physical probe | Circuit annotation | Analysis output, ignored by ordinary DEM decoders | +| Gate | An ideal operation in a circuit | Circuit builder | No noise unless a noise model attaches it | +| Channel | A physical CPTP map, often noise | Noise model or explicit channel op | Source of stochastic or coherent faults | +| Fault location | One independent place a modeled fault can occur | Fault catalog | Unit of fault enumeration and sampling | + +## Detectors, Observables, and Tracked Operators + +**Detectors** are syndrome bits. A detector is defined by a parity expression +over measurement records, such as "the previous ancilla measurement differs +from the same check in the prior round." Decoders consume detector flips as the +syndrome. + +**Observables** are measurement-defined experiment outputs. In QEC workflows +these are often logical measurement outcomes. They are still defined through +measurement records, so they are things the experiment can observe directly or +infer from recorded measurement data. Logical error rate terminology in PECOS +continues to refer to errors in these logical observables. + +**Tracked operators** are Pauli operators placed at a circuit point as probes. +They are not measured by that annotation and do not become detector syndrome +bits. Fault-analysis code asks whether propagated faults anticommute with the +tracked operator at that point. A tracked operator might be a logical operator, +a stabilizer, or another Pauli probe useful for analysis. + +Error events can therefore flip three independent kinds of output: + +- detectors: what syndrome bits changed +- observables: what measured logical or experiment outputs changed +- tracked operators: what Pauli probes anticommute with the propagated fault + +Do not merge observable IDs and tracked-operator IDs. Observable `0` is always +observable `0`; tracked operators have their own ID space and their own metadata. + +## Operator Construction + +Use the most structured representation that fits the situation: + +1. Typed constructors, such as `X(0) & Z(3)`, for ordinary code. +2. Sparse strings, such as `"X0 Z3"`, for compact text input with explicit + qubit indices. +3. Dense strings, such as `"XIIZ"`, for table-like input where character + position is the qubit index. + +When writing Rust code, the constructor style is the default: + +```rust +use pecos_core::pauli::*; +use pecos_core::PauliOperator; + +let logical_x = X(0) & X(1) & X(2); +let z_probe = Z(3); + +assert_eq!(logical_x.weight(), 3); +assert!(logical_x.commutes_with(&z_probe)); +``` + +String parsing is still useful when reading checks, user input, test fixtures, +or text formats: + +```rust +use pecos_core::{PauliOperator, PauliString}; + +let stabilizer: PauliString = "Z0 Z1 Z4 Z5".parse().unwrap(); +assert_eq!(stabilizer.weight(), 4); +``` + +Python exposes the same idea. Use `X(0) & Z(3)` for inline construction, +`PauliString.from_sparse_str(...)` for explicit sparse text, and +`PauliString.from_dense_str(...)` for dense text. `PauliString.from_str(...)` +auto-detects sparse versus dense notation. + +```python +from pecos.quantum import PauliString, X, Z + +probe = X(0) & X(1) & Z(3) +from_text = PauliString.from_str("X0 X1 Z3") + +assert probe == from_text +assert probe.to_sparse_str() == "+X0 X1 Z3" +assert probe.to_dense_str() == "+XXIZ" +``` + +In Pauli-algebra contexts, `X`, `Y`, and `Z` construct `PauliString` values. +In circuit-building contexts, use circuit APIs such as `Gate.x(...)`, +`TickCircuit.tick().x(...)`, or the corresponding builder methods. + +## Gates, Channels, Noise, and Idle Locations + +A **gate** is an ideal circuit operation. A **channel** is a physical map. Noise +models attach channels to selected circuit locations. + +`Idle` is a scheduling marker unless idle noise is attached explicitly. Adding +an `Idle` gate records timing structure; it should not silently inherit +single-qubit gate noise. To model idle decoherence, use a noise model or channel +API that explicitly targets idle locations. + +This keeps two actions separate: + +- changing circuit timing: add or remove idle locations +- changing the physical noise model: attach idle noise explicitly + +## DEMs and Fault Catalogs + +PECOS detector-error models represent detector and observable effects that +ordinary decoders consume. PECOS-specific metadata can also carry tracked +operators for analysis, but tracked operators are not logical observables and +ordinary DEM decoders should ignore them. + +The fault catalog gives the most detailed per-location view: + +- `affected_measurements`: raw measurement flips +- `affected_detectors`: syndrome flips +- `affected_observables`: measurement-defined logical or experiment outputs +- `affected_tracked_ops`: Pauli probes flipped by anticommutation + +## Recommended Surface-Code Memory Path + +For standard surface-code memory experiments: + +1. Build the patch and circuit with `SurfacePatch` and the surface circuit + builders. +2. Generate the circuit-level DEM with the surface decoder helpers. +3. Sample and decode with the native DEM sampler or a matching decoder backend. +4. Use the fault catalog when you need per-location fault anatomy, targeted + lookup decoding, or probability-weighted explanations for a syndrome. + +Use the lower-level `TickCircuit`, `DagCircuit`, `DemBuilder`, and fault-catalog +APIs when you are developing new circuit families, new analysis tools, or new +decoder integrations. diff --git a/docs/user-guide/python-pauli-qec.md b/docs/user-guide/python-pauli-qec.md index 3d0d31edc..9d3e2a27c 100644 --- a/docs/user-guide/python-pauli-qec.md +++ b/docs/user-guide/python-pauli-qec.md @@ -52,16 +52,32 @@ assert Pauli.X.to_int() == 1 ### Pauli Strings `PauliString` represents a multi-qubit Pauli operator with a phase from {+1, -1, +i, -i}. +For inline code, prefer constructor syntax such as `X(0) & Z(1)`. Use sparse +strings like `"X0 Z1"` when text input is useful and dense strings like `"XZ"` +for compact table-like input. ```python -from pecos_rslib import Pauli, PauliString +from pecos_rslib import Pauli, PauliString, X, Z -# From string notation -p = PauliString.from_str("XZI") # X on qubit 0, Z on qubit 1, I on qubit 2 -q = PauliString.from_str("ZXI") +# Constructor syntax +p = X(0) & Z(1) +q = Z(0) & X(1) # From list of (Pauli, qubit) pairs -p = PauliString([(Pauli.X, 0), (Pauli.Z, 1)]) +same_p = PauliString([(Pauli.X, 0), (Pauli.Z, 1)]) +assert p == same_p + +# From string notation +sparse_text = PauliString.from_sparse_str("X0 Z1") +dense_text = PauliString.from_dense_str("XZ") +auto_detected = PauliString.from_str("X0 Z1") +assert p == sparse_text +assert p == dense_text +assert p == auto_detected + +# To string notation +assert p.to_sparse_str() == "+X0 Z1" +assert p.to_dense_str() == "+XZ" # Get components print(p.get_paulis()) # [(Pauli.X, 0), (Pauli.Z, 1)] @@ -74,9 +90,9 @@ print(p) # Shows sparse representation with non-identity operators ### Matrix Representation ```python -from pecos_rslib import PauliString +from pecos_rslib import X, Z -p = PauliString.from_str("XZ") +p = X(0) & Z(1) matrix = p.to_matrix() # Returns complex matrix as list of lists # Each element is a (real, imag) tuple ``` @@ -86,11 +102,11 @@ matrix = p.to_matrix() # Returns complex matrix as list of lists `PauliStabilizerGroup` represents a group of mutually commuting Pauli strings with real phases (+1 or -1). This is the standard stabilizer group used in QEC. ```python -from pecos_rslib import PauliString, PauliStabilizerGroup +from pecos_rslib import PauliStabilizerGroup, Z # Create from generators -g1 = PauliString.from_str("ZZI") -g2 = PauliString.from_str("IZZ") +g1 = Z(0) & Z(1) +g2 = Z(1) & Z(2) group = PauliStabilizerGroup([g1, g2]) # Basic properties @@ -100,7 +116,7 @@ print(group.num_generators()) # 2 print(group.is_independent()) # True # Membership testing (GF(2) span) -ziz = PauliString.from_str("ZIZ") +ziz = Z(0) & Z(2) print(group.contains(ziz)) # True (ZIZ = ZZI * IZZ) print(group.contains_with_phase(ziz)) # True (with correct +1 phase) @@ -124,12 +140,12 @@ group = PauliStabilizerGroup.from_str("Z0 Z1\nZ1 Z2") ### Modifying Groups ```python -from pecos_rslib import PauliString, PauliStabilizerGroup +from pecos_rslib import PauliStabilizerGroup, X group = PauliStabilizerGroup.from_str("ZZI\nIZZ") # Add a generator (must commute with existing generators) -group.add_generator(PauliString.from_str("XXX")) +group.add_generator(X(0) & X(1) & X(2)) # Remove a generator by index removed = group.remove_generator(2) # Returns the removed PauliString @@ -144,10 +160,10 @@ group.merge(other) `PauliSequence` is an ordered list of Pauli strings with no constraints (they can anticommute). Provides GF(2) symplectic analysis. ```python -from pecos_rslib import PauliString, PauliSequence +from pecos_rslib import PauliSequence, X, Y, Z -p1 = PauliString.from_str("XZ") -p2 = PauliString.from_str("ZX") +p1 = X(0) & Z(1) +p2 = Z(0) & X(1) seq = PauliSequence([p1, p2]) # Analysis @@ -159,7 +175,7 @@ comm = seq.commutation_matrix() # comm[i][j] is 1 if seq[i] anticommutes with seq[j] # GF(2) membership -print(seq.contains(PauliString.from_str("YY"))) # True (XZ * ZX = -YY in GF(2) span) +print(seq.contains(Y(0) & Y(1))) # True (XZ * ZX = -YY in GF(2) span) # Row reduction to independent subset reduced = seq.row_reduce() @@ -237,22 +253,22 @@ for op in logicals: ### Syndrome Computation ```python -from pecos_rslib import StabilizerCode, PauliString +from pecos_rslib import StabilizerCode, X, Z code = StabilizerCode.repetition(3) # X error on qubit 0 -error = PauliString.from_str("XII") +error = X(0) syndrome = code.syndrome(error) print(syndrome) # [True, False] -- triggers first stabilizer # X error on qubit 1 -error = PauliString.from_str("IXI") +error = X(1) syndrome = code.syndrome(error) print(syndrome) # [True, True] -- triggers both stabilizers # Z error (undetectable by Z-stabilizers) -error = PauliString.from_str("ZII") +error = Z(0) syndrome = code.syndrome(error) print(syndrome) # [False, False] ``` diff --git a/docs/user-guide/quantum-operator-algebra.md b/docs/user-guide/quantum-operator-algebra.md index 05ebc6bb3..0e3c8b89f 100644 --- a/docs/user-guide/quantum-operator-algebra.md +++ b/docs/user-guide/quantum-operator-algebra.md @@ -109,12 +109,23 @@ All three implement the `PauliOperator` trait, which provides `multiply()`, `wei ### Parsing from Strings +Use constructors for ordinary code. Use sparse strings when explicit qubit +indices make text input clearer, and dense strings when positional notation is +useful for compact tables. + ```rust use pecos_core::PauliString; -let p: PauliString = "XZI".parse().unwrap(); // X(0) & Z(1) -let q: PauliString = "+XZZXI".parse().unwrap(); // with explicit phase -let r: PauliString = "-iYX".parse().unwrap(); // -i * Y(0) * X(1) +let sparse: PauliString = "X0 Z3".parse().unwrap(); +let dense: PauliString = "XIIZ".parse().unwrap(); +let explicit_sparse = PauliString::from_sparse_str("X0 Z3").unwrap(); +let explicit_dense = PauliString::from_dense_str("XIIZ").unwrap(); + +assert_eq!(sparse, dense); +assert_eq!(sparse, explicit_sparse); +assert_eq!(dense, explicit_dense); +assert_eq!(sparse.to_sparse_str(), "+X0 Z3"); +assert_eq!(sparse.to_dense_str(None), "+XIIZ"); ``` --- diff --git a/docs/user-guide/stabilizer-codes.md b/docs/user-guide/stabilizer-codes.md index d1a048d6a..a9907169c 100644 --- a/docs/user-guide/stabilizer-codes.md +++ b/docs/user-guide/stabilizer-codes.md @@ -51,11 +51,11 @@ Pauli strings are the fundamental building block. PECOS provides a concise const === ":fontawesome-brands-python: Python" ```python - from pecos.quantum import PauliString + from pecos.quantum import X, Z - # From string notation - p = PauliString.from_str("XZI") - q = PauliString.from_str("ZXI") + # Constructor notation + p = X(0) & Z(1) + q = Z(0) & X(1) # Commutation check print(p.commutes_with(q)) # False (anticommute) diff --git a/mkdocs.yml b/mkdocs.yml index 4aff8d6c1..d1f4dca87 100644 --- a/mkdocs.yml +++ b/mkdocs.yml @@ -50,6 +50,7 @@ nav: - Home: README.md - User Guide: - Getting Started: user-guide/getting-started.md + - PECOS Concepts: user-guide/pecos-concepts.md - Command Line Interface: user-guide/cli.md - QASM Simulation: user-guide/qasm-simulation.md - WASM Foreign Objects: user-guide/wasm-foreign-objects.md diff --git a/python/pecos-rslib/pecos_rslib.pyi b/python/pecos-rslib/pecos_rslib.pyi index 1e1f17f5e..5f8ab0a85 100644 --- a/python/pecos-rslib/pecos_rslib.pyi +++ b/python/pecos-rslib/pecos_rslib.pyi @@ -1025,7 +1025,42 @@ class Pauli: class PauliString: """String of Pauli operators.""" - ... + def __init__( + self, + paulis: list[tuple[Pauli, int]] | list[Pauli] | None = None, + phase: int = 0, + ) -> None: ... + @staticmethod + def from_str(s: str) -> PauliString: ... + @staticmethod + def from_dense_str(s: str) -> PauliString: ... + @staticmethod + def from_sparse_str(s: str) -> PauliString: ... + @staticmethod + def X(qubit: int) -> PauliString: ... + @staticmethod + def Y(qubit: int) -> PauliString: ... + @staticmethod + def Z(qubit: int) -> PauliString: ... + @staticmethod + def I() -> PauliString: ... # noqa: E743 + def to_dense_str(self, num_qubits: int | None = None) -> str: ... + def to_sparse_str(self) -> str: ... + def get_phase(self) -> int: ... + def get_paulis(self) -> list[tuple[Pauli, int]]: ... + def to_matrix(self, num_qubits: int | None = None) -> list[list[tuple[float, float]]]: ... + def commutes_with(self, other: PauliString) -> bool: ... + def anticommutes_with(self, other: PauliString) -> bool: ... + def weight(self) -> int: ... + def qubits(self) -> list[int]: ... + def __and__(self, other: PauliString) -> PauliString: ... + def __mul__(self, other: PauliString) -> PauliString: ... + def __neg__(self) -> PauliString: ... + def __eq__(self, other: object) -> bool: ... + +def X(qubit: int) -> PauliString: ... +def Y(qubit: int) -> PauliString: ... +def Z(qubit: int) -> PauliString: ... class PauliStabilizerGroup: """A group of commuting Pauli operators with real phases.""" diff --git a/python/pecos-rslib/src/pauli_bindings.rs b/python/pecos-rslib/src/pauli_bindings.rs index 943132a65..580eff4d0 100644 --- a/python/pecos-rslib/src/pauli_bindings.rs +++ b/python/pecos-rslib/src/pauli_bindings.rs @@ -256,44 +256,45 @@ impl PauliString { Ok(PauliString { inner }) } - /// Create `PauliString` from a string like "XYZ" or "IXZI" + /// Create `PauliString` from dense or sparse string notation. /// /// Args: - /// s: String of Pauli operators (I, X, Y, Z) + /// s: Dense notation like "XIZ" or sparse notation like "X0 Z2". /// /// Returns: - /// `PauliString` with operators on sequential qubits starting at 0 + /// `PauliString` parsed with the same auto-detection as Rust. /// /// Examples: - /// >>> ps = `PauliString.from_str("XYZ`") + /// >>> ps = PauliString.from_str("XYZ") /// >>> # X on qubit 0, Y on qubit 1, Z on qubit 2 + /// >>> ps = PauliString.from_str("X0 Z2") + /// >>> # X on qubit 0, Z on qubit 2 #[staticmethod] fn from_str(s: &str) -> PyResult { - // Parse string character by character - let mut paulis = Vec::new(); - - for (i, c) in s.chars().enumerate() { - let pauli = match c { - 'I' | 'i' => RustPauli::I, - 'X' | 'x' => RustPauli::X, - 'Y' | 'y' => RustPauli::Y, - 'Z' | 'z' => RustPauli::Z, - _ => { - return Err(pyo3::exceptions::PyValueError::new_err(format!( - "Invalid Pauli character '{c}' at position {i}. Must be 'I', 'X', 'Y', or 'Z'" - ))); - } - }; - - // Only store non-identity operators (sparse representation) - if pauli != RustPauli::I { - paulis.push((pauli, QubitId::new(i))); - } - } + s.parse::() + .map(|inner| PauliString { inner }) + .map_err(|err| pyo3::exceptions::PyValueError::new_err(err.to_string())) + } - let inner = RustPauliString::with_phase_and_paulis(QuarterPhase::PlusOne, paulis); + /// Create `PauliString` from dense string notation. + /// + /// Dense notation uses one Pauli character per qubit index, e.g. "XIZ" + /// means X on qubit 0 and Z on qubit 2. + #[staticmethod] + fn from_dense_str(s: &str) -> PyResult { + RustPauliString::from_dense_str(s) + .map(|inner| PauliString { inner }) + .map_err(|err| pyo3::exceptions::PyValueError::new_err(err.to_string())) + } - Ok(PauliString { inner }) + /// Create `PauliString` from sparse string notation. + /// + /// Sparse notation uses Pauli/qubit tokens, e.g. "X0 Z2". + #[staticmethod] + fn from_sparse_str(s: &str) -> PyResult { + RustPauliString::from_sparse_str(s) + .map(|inner| PauliString { inner }) + .map_err(|err| pyo3::exceptions::PyValueError::new_err(err.to_string())) } /// String representation @@ -329,6 +330,21 @@ impl PauliString { format!("{phase_str}{pauli_str}") } + /// Dense string representation with an explicit phase prefix. + /// + /// Example: `+XIZ` for X on qubit 0 and Z on qubit 2. + #[pyo3(signature = (num_qubits=None))] + fn to_dense_str(&self, num_qubits: Option) -> String { + self.inner.to_dense_str(num_qubits) + } + + /// Sparse string representation with an explicit phase prefix. + /// + /// Example: `+X0 Z2` for X on qubit 0 and Z on qubit 2. + fn to_sparse_str(&self) -> String { + self.inner.to_sparse_str() + } + /// Repr for debugging fn __repr__(&self) -> String { let phase = self.get_phase(); diff --git a/python/quantum-pecos/src/pecos/quantum/__init__.py b/python/quantum-pecos/src/pecos/quantum/__init__.py index 96bc863b6..d9c190b84 100644 --- a/python/quantum-pecos/src/pecos/quantum/__init__.py +++ b/python/quantum-pecos/src/pecos/quantum/__init__.py @@ -56,19 +56,23 @@ >>> errors = array([Pauli.X, Pauli.Y, Pauli.Z]) >>> # Create Pauli strings with convenient syntax - >>> from pecos.quantum import pauli_string - >>> ps = pauli_string("XYZ", phase=-1) # -X_0 Y_1 Z_2 + >>> from pecos.quantum import X, Z, pauli_string + >>> ps = X(0) & Z(3) + >>> from_text = pauli_string("X0 Z3") + >>> assert ps == from_text """ from __future__ import annotations +from collections.abc import Mapping as MappingABC +from collections.abc import Sequence as SequenceABC from typing import TYPE_CHECKING from pecos.quantum import commute, gate_groups from pecos.typing import INTEGER_TYPES if TYPE_CHECKING: - from collections.abc import Sequence + from collections.abc import Mapping, Sequence from pecos.typing import Integer @@ -118,6 +122,9 @@ SZdg, SZZdg, TableauWrapper, + X, + Y, + Z, adjust_tableau_string, sparse_stab, ) @@ -152,7 +159,7 @@ def pauli_string( - operators: str | Sequence[tuple[Pauli, int]] | dict[int, Pauli], + operators: str | Sequence[tuple[Pauli, int]] | Sequence[Pauli] | Mapping[int, Pauli], phase: complex = 1, ) -> PauliString: """Create a PauliString from a convenient specification. @@ -162,9 +169,10 @@ def pauli_string( Args: operators: One of the following: - - String like "XYZ" or "IXZI" (sequential qubits starting at 0) - - List of (Pauli, qubit_index) tuples - - Dict mapping qubit_index -> Pauli + - Sparse string like "X0 Z2" or dense string like "XIZ" + - Sequence of (Pauli, qubit_index) tuples + - Sequence of Pauli values for implicit qubits 0, 1, 2, ... + - Mapping from qubit_index -> Pauli phase: Phase factor, one of: - 1 or +1: Plus one (default) - -1: Minus one @@ -175,11 +183,19 @@ def pauli_string( PauliString object Examples: - >>> from pecos.quantum import Pauli, pauli_string + >>> from pecos.quantum import Pauli, X, Z, pauli_string - >>> # From string (sequential qubits) - >>> ps = pauli_string("XYZ") - >>> print(ps) # X_0 Y_1 Z_2 + >>> # Constructor syntax is preferred for ordinary code + >>> ps = X(0) & Z(2) + >>> print(ps) # X_0 Z_2 + + >>> # From sparse string (explicit qubit indices) + >>> ps = pauli_string("X0 Z2") + >>> print(ps) # X_0 Z_2 + + >>> # From dense string (character position is qubit index) + >>> ps = pauli_string("XIZ") + >>> print(ps) # X_0 Z_2 >>> # From list of (Pauli, qubit) tuples >>> ps = pauli_string([(Pauli.X, 0), (Pauli.Z, 2)]) @@ -229,14 +245,14 @@ def pauli_string( paulis = ps.get_paulis() return PauliString(paulis, phase=phase_code) return ps - if isinstance(operators, dict): - # Dict format - convert to list + if isinstance(operators, MappingABC): + # Mapping format - convert to list paulis = [(pauli, qubit) for qubit, pauli in sorted(operators.items())] return PauliString(paulis, phase=phase_code) - if isinstance(operators, list): - # Already in list format - return PauliString(operators, phase=phase_code) - msg = f"Invalid operators type: {type(operators)}. Must be str, dict, or list" + if isinstance(operators, SequenceABC): + # PyO3 constructor accepts lists, so normalize all Python sequences. + return PauliString(list(operators), phase=phase_code) + msg = f"Invalid operators type: {type(operators)}. Must be str, mapping, or sequence" raise TypeError(msg) @@ -295,6 +311,9 @@ def pauli_string( "TickHandle", "TickMeasureHandle", "TickPrepHandle", + "X", + "Y", + "Z", "adjust_tableau_string", "commute", "gate_groups", diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_pecos_concepts.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_pecos_concepts.rs new file mode 100644 index 000000000..1b1038856 --- /dev/null +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_pecos_concepts.rs @@ -0,0 +1,25 @@ +//! Auto-generated Rust tests from user-guide/pecos-concepts.md +//! DO NOT EDIT - Generated by scripts/docs/generate_doc_tests.py +#![allow(unused_imports, unused_variables, unused_mut, unused_assignments, dead_code, non_snake_case)] + + + +#[test] +fn test_user_guide_pecos_concepts_rust_1() { + use pecos_core::pauli::*; + use pecos_core::PauliOperator; + let logical_x = X(0) & X(1) & X(2); + let z_probe = Z(3); + + assert_eq!(logical_x.weight(), 3); + assert!(logical_x.commutes_with(&z_probe)); +} + + + +#[test] +fn test_user_guide_pecos_concepts_rust_2() { + use pecos_core::{PauliOperator, PauliString}; + let stabilizer: PauliString = "Z0 Z1 Z4 Z5".parse().unwrap(); + assert_eq!(stabilizer.weight(), 4); +} diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_quantum_operator_algebra.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_quantum_operator_algebra.rs index 5c54d3ba1..8e2c1daba 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_quantum_operator_algebra.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_quantum_operator_algebra.rs @@ -70,9 +70,16 @@ fn test_user_guide_quantum_operator_algebra_rust_3() { #[test] fn test_user_guide_quantum_operator_algebra_rust_4() { use pecos_core::PauliString; - let p: PauliString = "XZI".parse().unwrap(); // X(0) & Z(1) - let q: PauliString = "+XZZXI".parse().unwrap(); // with explicit phase - let r: PauliString = "-iYX".parse().unwrap(); // -i * Y(0) * X(1) + let sparse: PauliString = "X0 Z3".parse().unwrap(); + let dense: PauliString = "XIIZ".parse().unwrap(); + let explicit_sparse = PauliString::from_sparse_str("X0 Z3").unwrap(); + let explicit_dense = PauliString::from_dense_str("XIIZ").unwrap(); + + assert_eq!(sparse, dense); + assert_eq!(sparse, explicit_sparse); + assert_eq!(dense, explicit_dense); + assert_eq!(sparse.to_sparse_str(), "+X0 Z3"); + assert_eq!(sparse.to_dense_str(None), "+XIIZ"); } diff --git a/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py b/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py new file mode 100644 index 000000000..4f1c5abda --- /dev/null +++ b/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py @@ -0,0 +1,51 @@ +# Copyright 2026 The PECOS Developers +# +# Licensed under the Apache License, Version 2.0 + +from pecos_rslib import Pauli, PauliString, X, Z + + +def test_pauli_string_from_str_accepts_dense_and_sparse_formats() -> None: + expected = X(0) & X(1) & Z(3) + + assert PauliString.from_str("XXIZ") == expected + assert PauliString.from_str("X0 X1 Z3") == expected + assert PauliString.from_str("X 0 X 1 Z 3") == expected + + +def test_pauli_string_explicit_from_dense_and_sparse_formats() -> None: + expected = X(0) & Z(3) + + assert PauliString.from_dense_str("XIIZ") == expected + assert PauliString.from_sparse_str("X0 Z3") == expected + + +def test_pauli_string_from_str_sparse_keeps_phase_and_high_qubits() -> None: + pauli = PauliString.from_str("-i X2 Z10000") + + assert pauli.get_phase() == 3 + assert pauli.get_paulis() == [(Pauli.X, 2), (Pauli.Z, 10000)] + assert pauli.weight() == 2 + + +def test_pauli_string_dense_and_sparse_round_trips() -> None: + pauli = PauliString.from_sparse_str("-i X2 Z4") + + assert pauli.to_sparse_str() == "-iX2 Z4" + assert pauli.to_dense_str() == "-iIIXIZ" + assert pauli.to_dense_str(num_qubits=7) == "-iIIXIZII" + assert PauliString.from_sparse_str(pauli.to_sparse_str()) == pauli + assert PauliString.from_dense_str(pauli.to_dense_str()) == pauli + + +def test_quantum_namespace_exports_pauli_constructors() -> None: + import pecos.quantum as quantum + from pecos.quantum import pauli_string + + expected = X(0) & Z(3) + + assert quantum.X(0) & quantum.Z(3) == expected + assert pauli_string("X0 Z3") == expected + assert pauli_string("XIIZ") == expected + assert pauli_string(((quantum.Pauli.X, 0), (quantum.Pauli.Z, 3))) == expected + assert pauli_string({0: quantum.Pauli.X, 3: quantum.Pauli.Z}) == expected From 435a96781dd638b6ec1094cdf139158c950066ab Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 17:01:35 -0600 Subject: [PATCH 097/125] Polish quantum-info Python ergonomics --- docs/user-guide/quantum-info.md | 62 ++++++++- python/pecos-rslib/pecos_rslib.pyi | 21 ++- python/pecos-rslib/src/pauli_bindings.rs | 23 +++- .../pecos-rslib/src/quantum_info_bindings.rs | 128 +++++++++++++++--- .../quantum-pecos/src/pecos/quantum_info.py | 4 + .../tests/pecos/test_pauli_string_bindings.py | 18 +++ .../tests/pecos/test_quantum_info_bindings.py | 43 ++++++ 7 files changed, 277 insertions(+), 22 deletions(-) diff --git a/docs/user-guide/quantum-info.md b/docs/user-guide/quantum-info.md index 65d490844..7c70530d4 100644 --- a/docs/user-guide/quantum-info.md +++ b/docs/user-guide/quantum-info.md @@ -22,9 +22,29 @@ PECOS currently provides seven concrete channel representations: | `ChiMatrix` | Process matrix in the Pauli basis. | | `Stinespring` | Stinespring isometry. | -The representations use PECOS's little-endian qubit convention. Pauli-channel -labels are displayed with the highest-numbered qubit first, so label `IX` on two -qubits means identity on qubit 1 and X on qubit 0. +Use the representation that matches the question you are asking: + +| Goal | Start with | +| ---- | ---------- | +| Small pure-state examples | State vectors | +| Noisy states and entanglement measures | Density matrices | +| Operational noise construction | `KrausOps` | +| Complete positivity, trace preservation, and tomography reconstruction | `ChoiMatrix` | +| Pauli-basis channel diagnostics | `Ptm` | +| Sparse stochastic Pauli noise | `PauliChannel` | +| Environment/isometry models | `Stinespring` | + +PECOS uses these conventions consistently: + +| Convention | Meaning | +| ---------- | ------- | +| Qubit order | Little-endian: qubit 0 is the least-significant computational-basis bit. | +| Dense Pauli labels | Highest-numbered qubit first, so `IX` on two qubits means I on qubit 1 and X on qubit 0. | +| Sparse Pauli strings | Constructor and sparse text forms use explicit qubit IDs, e.g. `X(0) & Z(3)` or `"X0 Z3"`. | +| PTM basis order | Dense Pauli labels in PECOS basis-label order. | +| Superoperator order | Column-stacked operator vectorization. | +| Choi matrix | Built from PECOS's column-stacked superoperator convention. A trace-preserving channel has output partial trace equal to identity. | +| Subsystem order | Subsystem 0 is the fastest-varying tensor factor. Qubit helpers follow the same little-endian rule. | ```python from pecos.quantum_info import PauliChannel, process_fidelity @@ -66,7 +86,7 @@ For multi-qubit Pauli channels, pass a label-to-probability map: ```python from pecos.quantum_info import PauliChannel -channel = PauliChannel.from_probabilities( +from_labels = PauliChannel.from_probabilities( 2, { "II": 0.98, @@ -76,6 +96,30 @@ channel = PauliChannel.from_probabilities( ) ``` +You can also use `PauliString` keys when the channel is written in PECOS's typed +Pauli style: + +```python +from pecos.quantum import X, Z +from pecos_rslib import PauliString +from pecos.quantum_info import PauliChannel + +from_paulis = PauliChannel.from_probabilities( + 2, + { + PauliString.I(): 0.98, + X(0): 0.01, + Z(1): 0.01, + }, +) + +assert from_paulis.probabilities() == { + "II": 0.98, + "IX": 0.01, + "ZI": 0.01, +} +``` + ## Choi Validation `ChoiMatrix` exposes checks that are useful when importing reconstructed @@ -151,6 +195,8 @@ from pecos.quantum_info import ( entropy, hellinger_distance, negativity, + partial_trace_qubits, + partial_trace_subsystems, purity, schmidt_decomposition, shannon_entropy, @@ -177,6 +223,14 @@ bell_rho = [ assert abs(negativity(bell_rho, [2, 2], 1) - 0.5) < 1e-12 assert len(schmidt_decomposition(bell, [2, 2], [0])) == 2 +assert partial_trace_qubits(bell_rho, 2, [1]) == [ + [0.5 + 0.0j, 0.0 + 0.0j], + [0.0 + 0.0j, 0.5 + 0.0j], +] +assert partial_trace_subsystems(bell_rho, [2, 2], [1]) == [ + [0.5 + 0.0j, 0.0 + 0.0j], + [0.0 + 0.0j, 0.5 + 0.0j], +] assert shannon_entropy([0.5, 0.5], 2.0) == 1.0 assert hellinger_distance([1.0, 0.0], [0.0, 1.0]) == 1.0 diff --git a/python/pecos-rslib/pecos_rslib.pyi b/python/pecos-rslib/pecos_rslib.pyi index 5f8ab0a85..7c6f4e43d 100644 --- a/python/pecos-rslib/pecos_rslib.pyi +++ b/python/pecos-rslib/pecos_rslib.pyi @@ -1190,6 +1190,7 @@ class PauliPropRs: ComplexMatrix = Sequence[Sequence[complex]] RealMatrix = Sequence[Sequence[float]] +PauliProbabilityMap = Mapping[str | PauliString, float] | Sequence[tuple[str | PauliString, float]] class PauliChannel: """Sparse Pauli error channel represented by probabilities.""" @@ -1199,7 +1200,7 @@ class PauliChannel: @staticmethod def from_probabilities( num_qubits: int, - probabilities: Mapping[str, float] | Sequence[tuple[str, float]], + probabilities: PauliProbabilityMap, ) -> PauliChannel: ... def num_qubits(self) -> int: ... def probabilities(self) -> dict[str, float]: ... @@ -1295,6 +1296,16 @@ def schmidt_decomposition( dims: Sequence[int], left_subsystems: Sequence[int], ) -> list[tuple[float, list[complex], list[complex]]]: ... +def partial_trace_subsystems( + rho: ComplexMatrix, + dims: Sequence[int], + traced_subsystems: Sequence[int], +) -> list[list[complex]]: ... +def partial_trace_qubits( + rho: ComplexMatrix, + num_qubits: int, + traced_qubits: Sequence[int], +) -> list[list[complex]]: ... def hellinger_distance(left: Sequence[float], right: Sequence[float]) -> float: ... def hellinger_fidelity(left: Sequence[float], right: Sequence[float]) -> float: ... def process_fidelity(left: Ptm, right: Ptm) -> float: ... @@ -1421,6 +1432,14 @@ class quantum_info: [Sequence[complex], Sequence[int], Sequence[int]], list[tuple[float, list[complex], list[complex]]], ] + partial_trace_subsystems: Callable[ + [ComplexMatrix, Sequence[int], Sequence[int]], + list[list[complex]], + ] + partial_trace_qubits: Callable[ + [ComplexMatrix, int, Sequence[int]], + list[list[complex]], + ] hellinger_distance: Callable[[Sequence[float], Sequence[float]], float] hellinger_fidelity: Callable[[Sequence[float], Sequence[float]], float] process_fidelity: Callable[[Ptm, Ptm], float] diff --git a/python/pecos-rslib/src/pauli_bindings.rs b/python/pecos-rslib/src/pauli_bindings.rs index 580eff4d0..b76c66318 100644 --- a/python/pecos-rslib/src/pauli_bindings.rs +++ b/python/pecos-rslib/src/pauli_bindings.rs @@ -19,6 +19,8 @@ // pyfunction generates internal modules named after the function (X, Y, Z) #![allow(non_snake_case)] +use std::hash::{Hash, Hasher}; + use crate::prelude::{ Pauli as RustPauli, PauliOperator, PauliString as RustPauliString, QuarterPhase, QubitId, }; @@ -204,7 +206,7 @@ impl PauliString { }; // Build PauliString from input - let rust_paulis = if let Some(pauli_input) = paulis { + let mut rust_paulis = if let Some(pauli_input) = paulis { use pyo3::types::PyList; // Try to extract as a list - using cast() per PyO3 0.27 API @@ -250,6 +252,18 @@ impl PauliString { Vec::new() }; + rust_paulis.retain(|(pauli, _)| *pauli != RustPauli::I); + rust_paulis.sort_by_key(|(_, qubit)| *qubit); + for window in rust_paulis.windows(2) { + if window[0].1 == window[1].1 { + return Err(pyo3::exceptions::PyValueError::new_err(format!( + "multiple non-identity Pauli operators were specified for qubit {}; \ + use multiplication (*) if you intend to compose Paulis on the same qubit", + window[0].1.index() + ))); + } + } + // Construct RustPauliString using the new constructor let inner = RustPauliString::with_phase_and_paulis(rust_phase, rust_paulis); @@ -505,6 +519,13 @@ impl PauliString { self.inner == other.inner } + /// Hash for use in dictionaries and sets. + fn __hash__(&self) -> isize { + let mut hasher = std::collections::hash_map::DefaultHasher::new(); + self.inner.hash(&mut hasher); + hasher.finish() as isize + } + /// Number of non-identity Pauli operators. fn weight(&self) -> usize { self.inner.weight() diff --git a/python/pecos-rslib/src/quantum_info_bindings.rs b/python/pecos-rslib/src/quantum_info_bindings.rs index de5eb58b1..9374d43ac 100644 --- a/python/pecos-rslib/src/quantum_info_bindings.rs +++ b/python/pecos-rslib/src/quantum_info_bindings.rs @@ -14,25 +14,28 @@ use std::collections::BTreeMap; +use crate::pauli_bindings::PauliString as PyPauliString; use nalgebra::{DMatrix, DVector}; use num_complex::Complex64; -use pecos_core::PauliBitmaskSmall; +use pecos_core::{Pauli as RustPauli, PauliBitmaskSmall, QuarterPhase}; use pecos_quantum::{ - ChiMatrix as RustChiMatrix, ChoiMatrix as RustChoiMatrix, KrausOps as RustKrausOps, - PauliChannel as RustPauliChannel, ProcessTomographyDesign as RustProcessTomographyDesign, - Ptm as RustPtm, Stinespring as RustStinespring, SuperOp as RustSuperOp, average_gate_fidelity as rust_average_gate_fidelity, entropy as rust_entropy, gate_error as rust_gate_error, hellinger_distance as rust_hellinger_distance, hellinger_fidelity as rust_hellinger_fidelity, logarithmic_negativity as rust_logarithmic_negativity, negativity as rust_negativity, - pauli_basis_len, process_fidelity as rust_process_fidelity, purity as rust_purity, + partial_trace_qubits as rust_partial_trace_qubits, + partial_trace_subsystems as rust_partial_trace_subsystems, pauli_basis_len, + process_fidelity as rust_process_fidelity, purity as rust_purity, random_density_matrix as rust_random_density_matrix, random_quantum_channel as rust_random_quantum_channel, state_fidelity as rust_state_fidelity, state_fidelity_with_density_matrix as rust_state_fidelity_with_density_matrix, + ChiMatrix as RustChiMatrix, ChoiMatrix as RustChoiMatrix, KrausOps as RustKrausOps, + PauliChannel as RustPauliChannel, ProcessTomographyDesign as RustProcessTomographyDesign, + Ptm as RustPtm, Stinespring as RustStinespring, SuperOp as RustSuperOp, }; use pecos_random::PecosRng; use pyo3::prelude::*; -use pyo3::types::{PyDict, PyModule}; +use pyo3::types::{PyDict, PyModule, PyTuple}; type PySchmidtTerm = (f64, Vec, Vec); @@ -112,21 +115,86 @@ fn parse_pauli_label(num_qubits: usize, label: &str) -> PyResult PyResult { + if pauli_string.inner.get_phase() != QuarterPhase::PlusOne { + return Err(pyo3::exceptions::PyValueError::new_err( + "PauliChannel probabilities require unphased PauliString keys", + )); + } + + let mut out = PauliBitmaskSmall::identity(); + for (pauli, qubit) in pauli_string.inner.get_paulis() { + let qubit = qubit.index(); + if qubit >= num_qubits { + return Err(pyo3::exceptions::PyValueError::new_err(format!( + "PauliString key acts on qubit {qubit}, outside num_qubits={num_qubits}" + ))); + } + let single = match pauli { + RustPauli::I => PauliBitmaskSmall::identity(), + RustPauli::X => PauliBitmaskSmall::x(qubit), + RustPauli::Y => PauliBitmaskSmall::y(qubit), + RustPauli::Z => PauliBitmaskSmall::z(qubit), + }; + out = out.multiply(&single); + } + Ok(out) +} + +fn parse_pauli_probability_key( + num_qubits: usize, + key: &Bound<'_, PyAny>, +) -> PyResult { + if let Ok(label) = key.extract::() { + return parse_pauli_label(num_qubits, &label); + } + if let Ok(pauli_string) = key.extract::>() { + return parse_pauli_string_key(num_qubits, &pauli_string); + } + Err(pyo3::exceptions::PyTypeError::new_err( + "PauliChannel probability keys must be dense Pauli labels or PauliString objects", + )) +} + +fn insert_probability( + probabilities: &mut BTreeMap, + pauli: PauliBitmaskSmall, + probability: f64, +) -> PyResult<()> { + if probabilities.insert(pauli, probability).is_some() { + return Err(pyo3::exceptions::PyValueError::new_err( + "duplicate PauliChannel probability key", + )); + } + Ok(()) +} + fn pauli_probabilities_from_py( num_qubits: usize, probabilities: &Bound<'_, PyAny>, ) -> PyResult> { - let items: Vec<(String, f64)> = if let Ok(dict) = probabilities.cast::() { - dict.iter() - .map(|(key, value)| Ok((key.extract()?, value.extract()?))) - .collect::>()? + let mut out = BTreeMap::new(); + if let Ok(dict) = probabilities.cast::() { + for (key, value) in dict.iter() { + let pauli = parse_pauli_probability_key(num_qubits, &key)?; + insert_probability(&mut out, pauli, value.extract()?)?; + } } else { - probabilities.extract()? - }; - items - .into_iter() - .map(|(label, probability)| Ok((parse_pauli_label(num_qubits, &label)?, probability))) - .collect() + for item in probabilities.try_iter()? { + let tuple: Bound<'_, PyTuple> = item?.cast_into()?; + if tuple.len() != 2 { + return Err(pyo3::exceptions::PyValueError::new_err( + "PauliChannel probability sequences must contain (pauli, probability) pairs", + )); + } + let pauli = parse_pauli_probability_key(num_qubits, &tuple.get_item(0)?)?; + insert_probability(&mut out, pauli, tuple.get_item(1)?.extract()?)?; + } + } + Ok(out) } #[pyclass(name = "PauliChannel", module = "pecos_rslib.quantum_info")] @@ -715,6 +783,30 @@ fn schmidt_decomposition( .map_err(py_value_err) } +#[pyfunction] +fn partial_trace_subsystems( + rho: Vec>, + dims: Vec, + traced_subsystems: Vec, +) -> PyResult>> { + Ok(complex_matrix_to_rows( + &rust_partial_trace_subsystems(&complex_matrix_from_rows(rho)?, &dims, &traced_subsystems) + .map_err(py_value_err)?, + )) +} + +#[pyfunction] +fn partial_trace_qubits( + rho: Vec>, + num_qubits: usize, + traced_qubits: Vec, +) -> PyResult>> { + Ok(complex_matrix_to_rows( + &rust_partial_trace_qubits(&complex_matrix_from_rows(rho)?, num_qubits, &traced_qubits) + .map_err(py_value_err)?, + )) +} + #[pyfunction] fn hellinger_distance(left: Vec, right: Vec) -> PyResult { rust_hellinger_distance(&left, &right).map_err(py_value_err) @@ -795,6 +887,8 @@ pub fn register_quantum_info_module(parent: &Bound<'_, PyModule>) -> PyResult<() parent.add_function(wrap_pyfunction!(negativity, parent)?)?; parent.add_function(wrap_pyfunction!(logarithmic_negativity, parent)?)?; parent.add_function(wrap_pyfunction!(schmidt_decomposition, parent)?)?; + parent.add_function(wrap_pyfunction!(partial_trace_subsystems, parent)?)?; + parent.add_function(wrap_pyfunction!(partial_trace_qubits, parent)?)?; parent.add_function(wrap_pyfunction!(hellinger_distance, parent)?)?; parent.add_function(wrap_pyfunction!(hellinger_fidelity, parent)?)?; parent.add_function(wrap_pyfunction!(process_fidelity, parent)?)?; @@ -825,6 +919,8 @@ pub fn register_quantum_info_module(parent: &Bound<'_, PyModule>) -> PyResult<() "negativity", "logarithmic_negativity", "schmidt_decomposition", + "partial_trace_subsystems", + "partial_trace_qubits", "hellinger_distance", "hellinger_fidelity", "process_fidelity", diff --git a/python/quantum-pecos/src/pecos/quantum_info.py b/python/quantum-pecos/src/pecos/quantum_info.py index e20710811..5cc313105 100644 --- a/python/quantum-pecos/src/pecos/quantum_info.py +++ b/python/quantum-pecos/src/pecos/quantum_info.py @@ -24,6 +24,8 @@ logarithmic_negativity, matrix_unit_basis, negativity, + partial_trace_qubits, + partial_trace_subsystems, pauli_channel_diamond_distance, pauli_channel_diamond_norm, process_fidelity, @@ -53,6 +55,8 @@ "logarithmic_negativity", "matrix_unit_basis", "negativity", + "partial_trace_qubits", + "partial_trace_subsystems", "pauli_channel_diamond_distance", "pauli_channel_diamond_norm", "process_fidelity", diff --git a/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py b/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py index 4f1c5abda..01a945a58 100644 --- a/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py +++ b/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py @@ -2,6 +2,7 @@ # # Licensed under the Apache License, Version 2.0 +import pytest from pecos_rslib import Pauli, PauliString, X, Z @@ -38,6 +39,23 @@ def test_pauli_string_dense_and_sparse_round_trips() -> None: assert PauliString.from_dense_str(pauli.to_dense_str()) == pauli +def test_pauli_string_tuple_constructor_canonicalizes_for_hashing() -> None: + sorted_pauli = PauliString([(Pauli.X, 0), (Pauli.Y, 3)]) + unsorted_pauli = PauliString([(Pauli.Y, 3), (Pauli.X, 0)]) + constructed = X(0) & PauliString.Y(3) + + assert sorted_pauli == unsorted_pauli == constructed + assert hash(sorted_pauli) == hash(unsorted_pauli) == hash(constructed) + assert {sorted_pauli: "first", unsorted_pauli: "second"} == {constructed: "second"} + + +def test_pauli_string_tuple_constructor_rejects_duplicate_qubits() -> None: + with pytest.raises(ValueError, match="multiple non-identity"): + PauliString([(Pauli.X, 0), (Pauli.Z, 0)]) + + assert PauliString([(Pauli.I, 0), (Pauli.X, 0)]) == X(0) + + def test_quantum_namespace_exports_pauli_constructors() -> None: import pecos.quantum as quantum from pecos.quantum import pauli_string diff --git a/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py b/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py index 9f22a7489..9d97d0f6e 100644 --- a/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py +++ b/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py @@ -1,5 +1,7 @@ from __future__ import annotations +import pytest +from pecos.quantum import X, Z from pecos.quantum_info import ( ChiMatrix, ChoiMatrix, @@ -16,6 +18,8 @@ logarithmic_negativity, matrix_unit_basis, negativity, + partial_trace_qubits, + partial_trace_subsystems, pauli_channel_diamond_distance, pauli_channel_diamond_norm, process_fidelity, @@ -27,6 +31,7 @@ state_fidelity, state_fidelity_with_density_matrix, ) +from pecos_rslib import PauliString def assert_close(actual: float, expected: float, tol: float = 1e-12) -> None: @@ -57,6 +62,41 @@ def test_pauli_channel_exposes_probabilities_and_ptm() -> None: assert_close(pauli_channel_diamond_distance(channel, other), 0.3) +def test_pauli_channel_accepts_pauli_string_probability_keys() -> None: + channel = PauliChannel.from_probabilities( + 2, + { + PauliString.I(): 0.97, + X(0): 0.01, + Z(1): 0.02, + }, + ) + + assert channel.probabilities() == {"II": 0.97, "IX": 0.01, "ZI": 0.02} + assert_close(channel.total_error_rate(), 0.03) + + from_sequence = PauliChannel.from_probabilities( + 2, + [ + (PauliString.I(), 0.97), + (X(0), 0.01), + (Z(1), 0.02), + ], + ) + assert from_sequence.probabilities() == channel.probabilities() + + +def test_pauli_channel_rejects_ambiguous_pauli_string_keys() -> None: + with pytest.raises(ValueError, match="unphased"): + PauliChannel.from_probabilities(1, {-X(0): 1.0}) + + with pytest.raises(ValueError, match="outside num_qubits"): + PauliChannel.from_probabilities(1, {Z(1): 1.0}) + + with pytest.raises(ValueError, match="duplicate"): + PauliChannel.from_probabilities(1, [("X", 0.5), (X(0), 0.5)]) + + def test_choi_and_kraus_wrappers_round_trip_identity_channel() -> None: identity = Ptm.identity(1) choi = identity.to_choi() @@ -140,6 +180,9 @@ def test_state_measure_wrappers() -> None: assert_close(shannon_entropy([0.5, 0.5], 2.0), 1.0) assert_close(negativity(bell_density, [2, 2], 1), 0.5) assert_close(logarithmic_negativity(bell_density, [2, 2], 1), 1.0) + expected_reduced = [[0.5 + 0.0j, 0.0 + 0.0j], [0.0 + 0.0j, 0.5 + 0.0j]] + assert_matrix_close(partial_trace_qubits(bell_density, 2, [1]), expected_reduced) + assert_matrix_close(partial_trace_subsystems(bell_density, [2, 2], [1]), expected_reduced) assert_close(hellinger_distance([1.0, 0.0], [0.0, 1.0]), 1.0) assert_close(hellinger_fidelity([0.25, 0.75], [0.25, 0.75]), 1.0) schmidt = schmidt_decomposition(bell, [2, 2], [0]) From b500e52abe0dd16a8157df38d0282fedba8d1d6f Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Sun, 10 May 2026 18:25:33 -0600 Subject: [PATCH 098/125] Polish QEC UX and quantum info regressions --- Cargo.lock | 1 + crates/pecos-quantum/Cargo.toml | 1 + crates/pecos-quantum/src/channel.rs | 98 +++++ crates/pecos-quantum/src/measures.rs | 17 + crates/pecos-quantum/src/pauli_sequence.rs | 38 ++ crates/pecos-quantum/src/tick_circuit.rs | 355 +++++++++++++++++- .../src/bitmask_pauli_prop.rs | 7 +- crates/pecos-simulators/src/lib.rs | 2 + exp/pecos-lindblad/tests/four_qubit_smoke.rs | 4 +- .../pecos-rslib/src/dag_circuit_bindings.rs | 40 ++ python/pecos-rslib/src/pauli_bindings.rs | 4 +- .../pecos-rslib/src/quantum_info_bindings.rs | 6 +- python/quantum-pecos/pyproject.toml | 2 + python/quantum-pecos/src/pecos/__init__.py | 21 +- .../quantum-pecos/src/pecos/qec/__init__.py | 4 + .../src/pecos/qec/surface/__init__.py | 4 + .../src/pecos/qec/surface/decode.py | 173 +++++++++ .../tests/qec/test_qec_ux_entrypoints.py | 106 ++++++ uv.lock | 2 + 19 files changed, 869 insertions(+), 16 deletions(-) create mode 100644 python/quantum-pecos/tests/qec/test_qec_ux_entrypoints.py diff --git a/Cargo.lock b/Cargo.lock index 87e768442..25a506045 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -4322,6 +4322,7 @@ dependencies = [ "pecos-num", "pecos-random", "pecos-simulators", + "serde_json", "smallvec", "tket", ] diff --git a/crates/pecos-quantum/Cargo.toml b/crates/pecos-quantum/Cargo.toml index a829dd2b1..cd17ac25f 100644 --- a/crates/pecos-quantum/Cargo.toml +++ b/crates/pecos-quantum/Cargo.toml @@ -17,6 +17,7 @@ pecos-num.workspace = true pecos-random.workspace = true nalgebra.workspace = true num-complex.workspace = true +serde_json.workspace = true smallvec.workspace = true tket = { workspace = true, optional = true } log.workspace = true diff --git a/crates/pecos-quantum/src/channel.rs b/crates/pecos-quantum/src/channel.rs index ebecb3139..dddd07f7f 100644 --- a/crates/pecos-quantum/src/channel.rs +++ b/crates/pecos-quantum/src/channel.rs @@ -814,6 +814,29 @@ impl PauliChannel { Self::try_new(sum.num_qubits(), probabilities) } + /// Constructs a Pauli channel from probabilities keyed by [`PauliString`]. + /// + /// Pauli-string phases are ignored because Pauli channels apply + /// `P rho P†`, where global phase cancels. Repeated Pauli keys are + /// accumulated before validation. + /// + /// # Errors + /// + /// Returns an error when any Pauli string touches a qubit outside + /// `0..num_qubits`, a probability is invalid, or probabilities do not sum + /// to one. + pub fn from_pauli_strings(num_qubits: usize, probabilities: I) -> Result + where + I: IntoIterator, + { + let mut terms = BTreeMap::new(); + for (pauli, probability) in probabilities { + let pauli = pauli_string_to_bitmask(num_qubits, &pauli)?; + *terms.entry(pauli).or_insert(0.0) += probability; + } + Self::try_new(num_qubits, terms) + } + /// Converts a symbolic channel expression into a Pauli channel when it is /// a mixture of Pauli unitaries. /// @@ -3391,6 +3414,32 @@ mod tests { ); } + #[test] + fn pauli_channel_from_pauli_strings_accumulates_sparse_operator_keys() { + use pecos_core::pauli::{I, X, Z}; + + let channel = PauliChannel::from_pauli_strings( + 2, + [(I(), 0.5), (X(0) & Z(1), 0.2), (X(0) & Z(1), 0.3)], + ) + .unwrap(); + + assert_close(channel.probability(&PauliBitmaskSmall::identity()), 0.5); + assert_close( + channel.probability(&PauliBitmaskSmall::x(0).multiply(&PauliBitmaskSmall::z(1))), + 0.5, + ); + + let err = PauliChannel::from_pauli_strings(1, [(Z(2), 1.0)]).unwrap_err(); + assert_eq!( + err, + ChannelError::QubitOutOfRange { + num_qubits: 1, + qubit: 2 + } + ); + } + #[test] fn diagonal_ptm_values_are_not_probabilities() { let mut fidelities = BTreeMap::new(); @@ -3438,6 +3487,55 @@ mod tests { } } + #[test] + fn bit_flip_channel_matches_hand_ptm_and_choi_references() { + use pecos_core::pauli::{I, X}; + + let p = 0.2; + let channel = PauliChannel::from_pauli_strings(1, [(I(), 1.0 - p), (X(0), p)]).unwrap(); + let ptm = channel.to_ptm().unwrap(); + + assert_ptm_entry(&ptm, "I", "I", 1.0); + assert_ptm_entry(&ptm, "X", "X", 1.0); + assert_ptm_entry(&ptm, "Y", "Y", 1.0 - 2.0 * p); + assert_ptm_entry(&ptm, "Z", "Z", 1.0 - 2.0 * p); + + let choi = ptm.to_choi().unwrap(); + let matrix = choi.matrix(); + assert_complex_close(matrix[(0, 0)], Complex64::new(1.0 - p, 0.0)); + assert_complex_close(matrix[(0, 3)], Complex64::new(1.0 - p, 0.0)); + assert_complex_close(matrix[(3, 0)], Complex64::new(1.0 - p, 0.0)); + assert_complex_close(matrix[(3, 3)], Complex64::new(1.0 - p, 0.0)); + assert_complex_close(matrix[(1, 1)], Complex64::new(p, 0.0)); + assert_complex_close(matrix[(1, 2)], Complex64::new(p, 0.0)); + assert_complex_close(matrix[(2, 1)], Complex64::new(p, 0.0)); + assert_complex_close(matrix[(2, 2)], Complex64::new(p, 0.0)); + } + + #[test] + fn depolarizing_channel_matches_hand_diagonal_ptm_reference() { + use pecos_core::pauli::{I, X, Y, Z}; + + let p = 0.1; + let channel = PauliChannel::from_pauli_strings( + 1, + [ + (I(), 1.0 - p), + (X(0), p / 3.0), + (Y(0), p / 3.0), + (Z(0), p / 3.0), + ], + ) + .unwrap(); + let ptm = channel.to_ptm().unwrap(); + let non_identity_fidelity = 1.0 - 4.0 * p / 3.0; + + assert_ptm_entry(&ptm, "I", "I", 1.0); + assert_ptm_entry(&ptm, "X", "X", non_identity_fidelity); + assert_ptm_entry(&ptm, "Y", "Y", non_identity_fidelity); + assert_ptm_entry(&ptm, "Z", "Z", non_identity_fidelity); + } + #[test] fn dense_ptm_unitary_conjugation_known_one_qubit_cliffords() { let h = Ptm::from_unitary(&unitary::H(0), 1).unwrap(); diff --git a/crates/pecos-quantum/src/measures.rs b/crates/pecos-quantum/src/measures.rs index f142dee98..05d1602ab 100644 --- a/crates/pecos-quantum/src/measures.rs +++ b/crates/pecos-quantum/src/measures.rs @@ -1194,6 +1194,23 @@ mod tests { assert_close(mutual_information(&product, (2, 2)).unwrap(), 0.0); } + #[test] + fn concurrence_matches_werner_state_threshold_formula() { + fn werner_state(p: f64) -> DMatrix { + let bell = ket(&[ + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + ]); + pure_density(&bell) * Complex64::new(p, 0.0) + + DMatrix::identity(4, 4) * Complex64::new((1.0 - p) / 4.0, 0.0) + } + + assert_close(concurrence(&werner_state(0.5)).unwrap(), 0.25); + assert_close(concurrence(&werner_state(0.3)).unwrap(), 0.0); + } + #[test] fn negativity_matches_bell_and_product_states() { let bell = ket(&[ diff --git a/crates/pecos-quantum/src/pauli_sequence.rs b/crates/pecos-quantum/src/pauli_sequence.rs index 2c4ac0e3b..ab8965baf 100644 --- a/crates/pecos-quantum/src/pauli_sequence.rs +++ b/crates/pecos-quantum/src/pauli_sequence.rs @@ -1618,6 +1618,44 @@ mod tests { assert_eq!(c.row(1), vec![1, 1]); } + #[test] + fn test_f2_mul_matches_dense_reference_across_word_boundaries() { + fn dense_reference(a: &[Vec], b: &[Vec]) -> Vec> { + let rows = a.len(); + let inner = b.len(); + let cols = b.first().map_or(0, Vec::len); + let mut out = vec![vec![0; cols]; rows]; + for i in 0..rows { + for j in 0..cols { + let mut bit = 0; + for (k, b_row) in b.iter().enumerate().take(inner) { + bit ^= a[i][k] & b_row[j]; + } + out[i][j] = bit; + } + } + out + } + + let a_rows: Vec> = (0..5) + .map(|row| { + (0..130) + .map(|col| u8::from((row * 17 + col * 11 + row * col) % 7 < 3)) + .collect() + }) + .collect(); + let b_rows: Vec> = (0..130) + .map(|row| { + (0..7) + .map(|col| u8::from((row * 5 + col * 13 + row * col) % 11 < 5)) + .collect() + }) + .collect(); + + let packed = F2Matrix::from_rows(a_rows.clone()).mul(&F2Matrix::from_rows(b_rows.clone())); + assert_eq!(packed.rows(), dense_reference(&a_rows, &b_rows)); + } + #[test] fn test_f2_mul_inverse_gives_identity() { // Invertible 3x3 matrix over GF(2) diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index b93f47387..eee2226d3 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -72,6 +72,110 @@ use crate::Attribute; use crate::dag_circuit::{AnnotationKind, DagCircuit, PauliAnnotation}; use std::fmt; +fn meta_json_array(circuit: &TickCircuit, key: &str) -> Result, String> { + let Some(attr) = circuit.get_meta(key) else { + return Ok(Vec::new()); + }; + match attr { + Attribute::String(s) => { + if s.trim().is_empty() { + return Ok(Vec::new()); + } + serde_json::from_str::>(s) + .map_err(|e| format!("metadata {key:?} must be a JSON array: {e}")) + } + Attribute::Json(serde_json::Value::Array(values)) => Ok(values.clone()), + _ => Err(format!( + "metadata {key:?} must be a JSON array string or JSON array" + )), + } +} + +fn set_meta_json_array( + circuit: &mut TickCircuit, + key: &str, + values: &[serde_json::Value], +) -> Result<(), String> { + let json = + serde_json::to_string(values).map_err(|e| format!("could not serialize {key:?}: {e}"))?; + circuit.set_meta(key, Attribute::String(json)); + Ok(()) +} + +fn json_metadata_id(key: &str, id: u64) -> Result { + usize::try_from(id).map_err(|_| format!("metadata {key:?} id {id} does not fit usize")) +} + +fn next_metadata_id(values: &[serde_json::Value], key: &str) -> Result { + let mut max_id = None; + for value in values { + if let Some(id) = value.get("id").and_then(serde_json::Value::as_u64) { + let id = json_metadata_id(key, id)?; + max_id = Some(max_id.map_or(id, |max_id: usize| max_id.max(id))); + } + } + match max_id { + Some(max_id) => max_id + .checked_add(1) + .ok_or_else(|| format!("metadata {key:?} id counter overflow")), + None => Ok(values.len()), + } +} + +fn metadata_count(values: &[serde_json::Value], key: &str) -> Result { + let mut count = values.len(); + for value in values { + if let Some(id) = value.get("id").and_then(serde_json::Value::as_u64) { + let next = json_metadata_id(key, id)? + .checked_add(1) + .ok_or_else(|| format!("metadata {key:?} count overflow"))?; + count = count.max(next); + } + } + Ok(count) +} + +fn metadata_count_attr(values: &[serde_json::Value], key: &str) -> Result { + let count = metadata_count(values, key)?; + let count = i64::try_from(count) + .map_err(|_| format!("metadata {key:?} count {count} does not fit i64"))?; + Ok(Attribute::Int(count)) +} + +fn ensure_unique_metadata_id( + values: &[serde_json::Value], + key: &str, + id_name: &str, + id: usize, +) -> Result<(), String> { + for value in values { + if let Some(existing) = value.get("id").and_then(serde_json::Value::as_u64) { + let existing = json_metadata_id(key, existing)?; + if existing == id { + return Err(format!("{key} metadata already contains {id_name} {id}")); + } + } + } + Ok(()) +} + +fn observable_id_from_label(label: Option<&str>) -> Result, String> { + let Some(label) = label else { + return Ok(None); + }; + let Some(rest) = label.strip_prefix('L') else { + return Ok(None); + }; + if rest.is_empty() { + return Ok(None); + } + rest.parse::().map(Some).map_err(|_| { + format!( + "observable label {label:?} starts with 'L' but does not contain a valid integer id" + ) + }) +} + /// Error when trying to add a gate that uses a qubit already in use in this tick. #[derive(Debug, Clone, PartialEq, Eq)] pub struct QubitConflictError { @@ -778,6 +882,96 @@ impl TickCircuit { self.circuit_attrs.get(key) } + /// Add detector metadata defined by measurement-record offsets. + /// + /// This appends one entry to the circuit-level `"detectors"` JSON metadata + /// list and updates `"num_detectors"`. It is intended for circuits whose + /// detector definitions are stored in metadata rather than as direct + /// [`TickMeasRef`] annotations. + /// + /// # Errors + /// + /// Returns an error if existing detector metadata is not a JSON array, if + /// JSON serialization fails, or if `detector_id` duplicates an existing + /// explicit detector id. + pub fn add_detector_metadata( + &mut self, + records: &[i64], + coords: Option<&[f64]>, + label: Option<&str>, + detector_id: Option, + ) -> Result { + let mut detectors = meta_json_array(self, "detectors")?; + let id = match detector_id { + Some(id) => id, + None => next_metadata_id(&detectors, "detectors")?, + }; + ensure_unique_metadata_id(&detectors, "detectors", "detector_id", id)?; + + let mut detector = serde_json::Map::new(); + detector.insert("id".to_string(), serde_json::json!(id)); + detector.insert("records".to_string(), serde_json::json!(records)); + if let Some(coords) = coords { + detector.insert("coords".to_string(), serde_json::json!(coords)); + } + if let Some(label) = label { + detector.insert("label".to_string(), serde_json::json!(label)); + } + detectors.push(serde_json::Value::Object(detector)); + set_meta_json_array(self, "detectors", &detectors)?; + self.set_meta( + "num_detectors", + metadata_count_attr(&detectors, "detectors")?, + ); + Ok(id) + } + + /// Add observable metadata defined by measurement-record offsets. + /// + /// Standard observables live in the decoder `L` id space. A label of + /// `"L3"` therefore selects observable id 3 unless `observable_id` is + /// provided, in which case the two must agree. + /// + /// # Errors + /// + /// Returns an error if existing observable metadata is not a JSON array, if + /// JSON serialization fails, if the label/id conflict, or if the selected + /// id duplicates an existing explicit observable id. + pub fn add_observable_metadata( + &mut self, + records: &[i64], + observable_id: Option, + label: Option<&str>, + ) -> Result { + let mut observables = meta_json_array(self, "observables")?; + let label_id = observable_id_from_label(label)?; + if let (Some(observable_id), Some(label_id)) = (observable_id, label_id) + && observable_id != label_id + { + return Err(format!( + "observable_id={observable_id} conflicts with label id L{label_id}" + )); + } + let id = observable_id + .or(label_id) + .map_or_else(|| next_metadata_id(&observables, "observables"), Ok)?; + ensure_unique_metadata_id(&observables, "observables", "observable_id", id)?; + + let mut observable = serde_json::Map::new(); + observable.insert("id".to_string(), serde_json::json!(id)); + observable.insert("records".to_string(), serde_json::json!(records)); + if let Some(label) = label { + observable.insert("label".to_string(), serde_json::json!(label)); + } + observables.push(serde_json::Value::Object(observable)); + set_meta_json_array(self, "observables", &observables)?; + self.set_meta( + "num_observables", + metadata_count_attr(&observables, "observables")?, + ); + Ok(id) + } + /// Get all circuit-level attributes. pub fn circuit_attrs(&self) -> impl Iterator { self.circuit_attrs.iter() @@ -841,6 +1035,8 @@ impl TickCircuit { self.next_tick = 0; self.circuit_attrs.clear(); self.gate_signatures.clear(); + self.annotations.clear(); + self.next_meas_record = 0; } /// Try to compile an ideal circuit plus a gate-triggered noise model into @@ -852,18 +1048,25 @@ impl TickCircuit { /// conflicts. This produces a concrete inline representation useful for /// inspection, visualization, and simulators that consume interleaved /// channel operations directly. + /// + /// For measurements, `channels_after` is literal: returned channels are + /// placed after the measurement operation. Physical pre-measurement noise + /// and classical readout flips should use explicit APIs for those concepts + /// instead of being hidden in this post-gate hook. + /// /// # Errors /// /// Returns an error if the source circuit already contains channel /// operations. Apply either inline channels or a noise model, not both. pub fn try_with_noise(&self, noise: &N) -> Result { - if let Some((tick_idx, _)) = self - .iter_gates_with_tick() - .find(|(_, gate)| gate.is_channel()) - { - return Err(format!( - "with_noise cannot apply a noise model to a circuit that already contains channel operations (first channel at tick {tick_idx})" - )); + for (tick_idx, tick) in self.ticks.iter().enumerate() { + for (gate_idx, gate) in tick.gates().iter().enumerate() { + if gate.is_channel() { + return Err(format!( + "with_noise cannot apply a noise model to a circuit that already contains channel operations (first channel at tick {tick_idx} gate {gate_idx})" + )); + } + } } let mut out = Self::new(); @@ -3059,6 +3262,82 @@ mod tests { assert_eq!(tc.num_ticks(), 1); } + #[test] + fn test_reset_clears_annotations_and_measurement_counter() { + let mut tc = TickCircuit::new(); + let first_measurement = tc.tick().mz(&[0]); + tc.detector(&first_measurement); + tc.observable(&first_measurement); + tc.tracked_operator(pecos_core::pauli::Z(0)); + + assert_eq!(tc.num_measurements(), 1); + assert_eq!(tc.annotations().len(), 3); + + tc.reset(); + + assert_eq!(tc.num_ticks(), 0); + assert_eq!(tc.num_measurements(), 0); + assert!(tc.annotations().is_empty()); + + let reused_measurement = tc.tick().mz(&[1]); + assert_eq!(reused_measurement[0].record_idx, 0); + } + + #[test] + fn test_metadata_helpers_build_detector_and_observable_json() { + let mut tc = TickCircuit::new(); + + let detector_id = tc + .add_detector_metadata(&[-1], Some(&[0.0, 1.0, 2.0]), Some("d0"), None) + .unwrap(); + let observable_id = tc + .add_observable_metadata(&[-1, -2], None, Some("L2")) + .unwrap(); + + assert_eq!(detector_id, 0); + assert_eq!(observable_id, 2); + assert_eq!(tc.get_meta("num_detectors"), Some(&Attribute::Int(1))); + assert_eq!(tc.get_meta("num_observables"), Some(&Attribute::Int(3))); + + let detectors = match tc.get_meta("detectors").unwrap() { + Attribute::String(value) => value, + other => panic!("expected detectors JSON string, got {other:?}"), + }; + assert_eq!( + detectors, + r#"[{"coords":[0.0,1.0,2.0],"id":0,"label":"d0","records":[-1]}]"# + ); + + let observables = match tc.get_meta("observables").unwrap() { + Attribute::String(value) => value, + other => panic!("expected observables JSON string, got {other:?}"), + }; + assert_eq!(observables, r#"[{"id":2,"label":"L2","records":[-1,-2]}]"#); + } + + #[test] + fn test_metadata_helpers_reject_conflicts_and_duplicates() { + let mut tc = TickCircuit::new(); + + let err = tc + .add_observable_metadata(&[-1], Some(1), Some("L2")) + .unwrap_err(); + assert!(err.contains("conflicts")); + + tc.add_detector_metadata(&[-1], None, None, Some(7)) + .unwrap(); + let err = tc + .add_detector_metadata(&[-2], None, None, Some(7)) + .unwrap_err(); + assert!(err.contains("already contains detector_id 7")); + + tc.add_observable_metadata(&[-1], Some(3), None).unwrap(); + let err = tc + .add_observable_metadata(&[-2], Some(3), None) + .unwrap_err(); + assert!(err.contains("already contains observable_id 3")); + } + #[test] fn test_reserve_ticks() { let mut tc = TickCircuit::new(); @@ -3626,6 +3905,67 @@ mod tests { ); } + #[test] + fn test_with_noise_places_measurement_channels_after_measurement_tick() { + let mut tc = TickCircuit::new(); + tc.tick().mz(&[0]); + + let noisy = tc.with_noise(&|gate: &Gate| { + if gate.gate_type == GateType::MZ { + vec![pecos_core::channel::Dephasing(0.25, 0)] + } else { + Vec::new() + } + }); + + assert_eq!(noisy.num_ticks(), 2); + assert_eq!( + noisy.get_tick(0).unwrap().gates()[0].gate_type, + GateType::MZ + ); + let channel = &noisy.get_tick(1).unwrap().gates()[0]; + assert!(channel.is_channel()); + assert_eq!(channel.qubits.as_slice(), &[QubitId::from(0)]); + } + + #[test] + fn test_with_noise_packs_disjoint_channels_and_splits_conflicts() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[0]).x(&[1]); + + let noisy = tc.with_noise(&|gate: &Gate| { + gate.qubits + .iter() + .flat_map(|q| { + [ + pecos_core::channel::Depolarizing(0.01, q.index()), + pecos_core::channel::Dephasing(0.02, q.index()), + ] + }) + .collect() + }); + + assert_eq!(noisy.num_ticks(), 3); + assert_eq!(noisy.get_tick(1).unwrap().gates().len(), 2); + assert_eq!(noisy.get_tick(2).unwrap().gates().len(), 2); + assert!( + noisy + .get_tick(1) + .unwrap() + .gates() + .iter() + .all(Gate::is_channel) + ); + assert!( + noisy + .get_tick(2) + .unwrap() + .gates() + .iter() + .all(Gate::is_channel) + ); + } + #[test] fn test_with_noise_rejects_existing_channel_operations() { let mut tc = TickCircuit::new(); @@ -3638,6 +3978,7 @@ mod tests { assert!(err.contains("already contains channel operations")); assert!(err.contains("tick 0")); + assert!(err.contains("gate 0")); } #[test] diff --git a/crates/pecos-simulators/src/bitmask_pauli_prop.rs b/crates/pecos-simulators/src/bitmask_pauli_prop.rs index 19b957215..c09db915a 100644 --- a/crates/pecos-simulators/src/bitmask_pauli_prop.rs +++ b/crates/pecos-simulators/src/bitmask_pauli_prop.rs @@ -21,7 +21,12 @@ use crate::clifford_gateable::{CliffordGateable, MeasurementResult}; use crate::quantum_simulator::QuantumSimulator; use pecos_core::{BitmaskStorage, PauliBitmaskSmall, QubitId}; -/// A phase-free Pauli propagator backed by `PauliBitmaskSmall`. +/// Internal phase-free Pauli propagator backed by `PauliBitmaskSmall`. +/// +/// This is a performance helper for fault analysis and other hot internal +/// propagation paths. User-facing code should prefer Pauli strings and the +/// standard simulator APIs. +#[doc(hidden)] #[derive(Clone, Debug)] pub struct BitmaskPauliProp { label: PauliBitmaskSmall, diff --git a/crates/pecos-simulators/src/lib.rs b/crates/pecos-simulators/src/lib.rs index 448e0b3f6..4ffe87828 100644 --- a/crates/pecos-simulators/src/lib.rs +++ b/crates/pecos-simulators/src/lib.rs @@ -12,6 +12,7 @@ pub mod arbitrary_rotation_gateable; pub mod batched_ops; +#[doc(hidden)] pub mod bitmask_pauli_prop; pub mod circuit_executor; pub mod clifford_frame; @@ -59,6 +60,7 @@ pub mod symbolic_sparse_stab_bitset; pub use arbitrary_rotation_gateable::ArbitraryRotationGateable; pub use batched_ops::{BatchedOps, CommandBuffer, RawOps}; +#[doc(hidden)] pub use bitmask_pauli_prop::BitmaskPauliProp; pub use circuit_executor::{CircuitExecutor, GateSystem, GateSystemRegistry, execute_batched}; pub use clifford_gateable::{CliffordGateable, MeasurementResult}; diff --git a/exp/pecos-lindblad/tests/four_qubit_smoke.rs b/exp/pecos-lindblad/tests/four_qubit_smoke.rs index a9487bc74..5fcbed35c 100644 --- a/exp/pecos-lindblad/tests/four_qubit_smoke.rs +++ b/exp/pecos-lindblad/tests/four_qubit_smoke.rs @@ -22,8 +22,8 @@ use num_complex::Complex64; use pecos_lindblad::matrix::{self, Matrix}; use pecos_lindblad::{ - synthesize_exact_unitary, synthesize_numerical, Gate, Lindbladian, Pauli1, PauliString, - DEFAULT_N_STEPS, + DEFAULT_N_STEPS, Gate, Lindbladian, Pauli1, PauliString, synthesize_exact_unitary, + synthesize_numerical, }; fn kron_all(ops: &[&Matrix]) -> Matrix { diff --git a/python/pecos-rslib/src/dag_circuit_bindings.rs b/python/pecos-rslib/src/dag_circuit_bindings.rs index 8c4174ead..1961eac83 100644 --- a/python/pecos-rslib/src/dag_circuit_bindings.rs +++ b/python/pecos-rslib/src/dag_circuit_bindings.rs @@ -2200,6 +2200,11 @@ impl PyTickCircuit { self.inner.gate_count() } + /// Get the total number of measurement results produced so far. + fn num_measurements(&self) -> usize { + self.inner.num_measurements() + } + /// Get the next tick index that will be allocated. fn next_tick_index(&self) -> usize { self.inner.next_tick_index() @@ -2245,6 +2250,41 @@ impl PyTickCircuit { .map(|attr| attribute_to_py(py, attr)) } + /// Add detector metadata using measurement-record offsets. + /// + /// This is the typed equivalent of appending to the circuit-level + /// ``"detectors"`` JSON metadata list. Use ``detector(...)`` when you + /// already have explicit measurement handles from this TickCircuit. + #[pyo3(signature = (records, coords=None, label=None, detector_id=None))] + fn add_detector( + &mut self, + records: Vec, + coords: Option>, + label: Option, + detector_id: Option, + ) -> PyResult { + self.inner + .add_detector_metadata(&records, coords.as_deref(), label.as_deref(), detector_id) + .map_err(pyo3::exceptions::PyValueError::new_err) + } + + /// Add observable metadata using measurement-record offsets. + /// + /// Standard observables live in the ``L`` decoder ID space. A label of + /// ``"L3"`` therefore selects observable id 3 unless ``observable_id`` is + /// provided, in which case the two must agree. + #[pyo3(signature = (records, observable_id=None, label=None))] + fn add_observable( + &mut self, + records: Vec, + observable_id: Option, + label: Option, + ) -> PyResult { + self.inner + .add_observable_metadata(&records, observable_id, label.as_deref()) + .map_err(pyo3::exceptions::PyValueError::new_err) + } + // --- Circuit manipulation --- /// Clear the circuit and start fresh. diff --git a/python/pecos-rslib/src/pauli_bindings.rs b/python/pecos-rslib/src/pauli_bindings.rs index b76c66318..c0ab8c755 100644 --- a/python/pecos-rslib/src/pauli_bindings.rs +++ b/python/pecos-rslib/src/pauli_bindings.rs @@ -520,10 +520,10 @@ impl PauliString { } /// Hash for use in dictionaries and sets. - fn __hash__(&self) -> isize { + fn __hash__(&self) -> u64 { let mut hasher = std::collections::hash_map::DefaultHasher::new(); self.inner.hash(&mut hasher); - hasher.finish() as isize + hasher.finish() } /// Number of non-identity Pauli operators. diff --git a/python/pecos-rslib/src/quantum_info_bindings.rs b/python/pecos-rslib/src/quantum_info_bindings.rs index 9374d43ac..a4ffc5958 100644 --- a/python/pecos-rslib/src/quantum_info_bindings.rs +++ b/python/pecos-rslib/src/quantum_info_bindings.rs @@ -19,6 +19,9 @@ use nalgebra::{DMatrix, DVector}; use num_complex::Complex64; use pecos_core::{Pauli as RustPauli, PauliBitmaskSmall, QuarterPhase}; use pecos_quantum::{ + ChiMatrix as RustChiMatrix, ChoiMatrix as RustChoiMatrix, KrausOps as RustKrausOps, + PauliChannel as RustPauliChannel, ProcessTomographyDesign as RustProcessTomographyDesign, + Ptm as RustPtm, Stinespring as RustStinespring, SuperOp as RustSuperOp, average_gate_fidelity as rust_average_gate_fidelity, entropy as rust_entropy, gate_error as rust_gate_error, hellinger_distance as rust_hellinger_distance, hellinger_fidelity as rust_hellinger_fidelity, @@ -29,9 +32,6 @@ use pecos_quantum::{ random_density_matrix as rust_random_density_matrix, random_quantum_channel as rust_random_quantum_channel, state_fidelity as rust_state_fidelity, state_fidelity_with_density_matrix as rust_state_fidelity_with_density_matrix, - ChiMatrix as RustChiMatrix, ChoiMatrix as RustChoiMatrix, KrausOps as RustKrausOps, - PauliChannel as RustPauliChannel, ProcessTomographyDesign as RustProcessTomographyDesign, - Ptm as RustPtm, Stinespring as RustStinespring, SuperOp as RustSuperOp, }; use pecos_random::PecosRng; use pyo3::prelude::*; diff --git a/python/quantum-pecos/pyproject.toml b/python/quantum-pecos/pyproject.toml index 1d22357c1..f5829b8ee 100644 --- a/python/quantum-pecos/pyproject.toml +++ b/python/quantum-pecos/pyproject.toml @@ -29,6 +29,7 @@ license = { file = "LICENSE"} keywords = ["quantum", "QEC", "simulation", "PECOS"] dependencies = [ "pecos-rslib==0.8.0.dev8", + "pecos-rslib-exp==0.8.0.dev8", "pecos-rslib-llvm==0.8.0.dev8", "phir>=0.3.3", "networkx>=2.1.0", @@ -88,6 +89,7 @@ cuda = [ [tool.uv.sources] pecos-rslib = { workspace = true } +pecos-rslib-exp = { workspace = true } pecos-rslib-llvm = { workspace = true } pecos-rslib-cuda = { workspace = true } diff --git a/python/quantum-pecos/src/pecos/__init__.py b/python/quantum-pecos/src/pecos/__init__.py index af1bc5e6e..f020f7905 100644 --- a/python/quantum-pecos/src/pecos/__init__.py +++ b/python/quantum-pecos/src/pecos/__init__.py @@ -31,6 +31,7 @@ from typing import TYPE_CHECKING import pecos_rslib +import pecos_rslib_exp from pecos_rslib import ( AngleSource, # Angle source specification for gate decomposition Array, # Array type with generic dtype support (Array[f64], etc.) @@ -285,11 +286,23 @@ def __getattr__(name: str): general_noise = pecos_rslib.general_noise state_vector = pecos_rslib.state_vector sparse_stab = pecos_rslib.sparse_stab -stabilizer = pecos_rslib.stabilizer stab_vec = pecos_rslib.stab_vec density_matrix = pecos_rslib.density_matrix hugr_engine = pecos_rslib.hugr_engine +# Native QEC simulation/fault-catalog entry points. +# +# These are Rust-backed APIs from pecos-rslib-exp, re-exported here so common +# workflows can stay in the main `pecos` namespace: +# from pecos import sim_neo, stabilizer, depolarizing +depolarizing = pecos_rslib_exp.depolarizing +fault_catalog = pecos_rslib_exp.fault_catalog +meas_sampling = pecos_rslib_exp.meas_sampling +sim_neo = pecos_rslib_exp.sim_neo +stab_mps = pecos_rslib_exp.stab_mps +stabilizer = pecos_rslib_exp.stabilizer +statevec = pecos_rslib_exp.statevec + # Re-export noise model builder classes for direct instantiation GeneralNoiseModelBuilder = pecos_rslib.GeneralNoiseModelBuilder @@ -377,6 +390,7 @@ def __getattr__(name: str): "decoders", "delete", "density_matrix", + "depolarizing", "depolarizing_noise", "diag", "dtypes", @@ -385,6 +399,7 @@ def __getattr__(name: str): "exp", "f32", "f64", + "fault_catalog", "floor", "general_noise", "get_guppy_backends", @@ -406,6 +421,7 @@ def __getattr__(name: str): "math", "max", "mean", + "meas_sampling", "min", "nan", "newton", @@ -428,14 +444,17 @@ def __getattr__(name: str): "round", "selene_engine", "sim", + "sim_neo", "simulators", "sin", "sinh", "sparse_stab", "sqrt", + "stab_mps", "stab_vec", "stabilizer", "state_vector", + "statevec", "stats", "std", "sum", diff --git a/python/quantum-pecos/src/pecos/qec/__init__.py b/python/quantum-pecos/src/pecos/qec/__init__.py index de5fe5142..362efa148 100644 --- a/python/quantum-pecos/src/pecos/qec/__init__.py +++ b/python/quantum-pecos/src/pecos/qec/__init__.py @@ -92,12 +92,14 @@ StabilizerSupport, SurfacePatch, SurfacePatchBuilder, + build_memory_circuit, compute_x_stabilizer_supports, compute_z_stabilizer_supports, generate_nonrotated_surface_layout, generate_surface_layout, parity_matrix_x, parity_matrix_z, + surface_code_memory, ) __all__ = [ @@ -170,6 +172,8 @@ "StabilizerSupport", "SurfacePatch", "SurfacePatchBuilder", + "build_memory_circuit", + "surface_code_memory", # Color code "ColorCode488", "ColorCode488Builder", diff --git a/python/quantum-pecos/src/pecos/qec/surface/__init__.py b/python/quantum-pecos/src/pecos/qec/surface/__init__.py index ae1db8996..fb702c3f1 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/__init__.py +++ b/python/quantum-pecos/src/pecos/qec/surface/__init__.py @@ -56,6 +56,7 @@ NoiseModel, SimulationResult, SurfaceDecoder, + build_memory_circuit, build_native_sampler, build_stim_circuit_from_patch, generate_circuit_level_dem, @@ -63,6 +64,7 @@ generate_repetition_code_dem, generate_surface_code_dem, run_noisy_memory_experiment, + surface_code_memory, syndromes_to_detection_events, ) from pecos.qec.surface.layouts import ( @@ -140,6 +142,7 @@ "NoiseModel", "SimulationResult", "SurfaceDecoder", + "build_memory_circuit", "build_native_sampler", "build_stim_circuit_from_patch", "generate_circuit_level_dem", @@ -147,6 +150,7 @@ "generate_repetition_code_dem", "generate_surface_code_dem", "run_noisy_memory_experiment", + "surface_code_memory", "syndromes_to_detection_events", # Visualization "plot_patch", diff --git a/python/quantum-pecos/src/pecos/qec/surface/decode.py b/python/quantum-pecos/src/pecos/qec/surface/decode.py index f4efd9522..6ffb604b9 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/decode.py +++ b/python/quantum-pecos/src/pecos/qec/surface/decode.py @@ -57,6 +57,15 @@ from pecos.qec.surface.patch import Stabilizer, SurfacePatch +def _validate_probability(name: str, value: float) -> float: + """Return ``value`` as a float after validating it is a probability.""" + probability = float(value) + if not 0.0 <= probability <= 1.0: + msg = f"{name} must be a probability in [0, 1], got {value!r}" + raise ValueError(msg) + return probability + + class DecoderType(str, Enum): """Available decoder backends.""" @@ -93,6 +102,12 @@ class NoiseModel: t1: float | None = None t2: float | None = None + @staticmethod + def uniform(physical_error_rate: float) -> NoiseModel: + """Create a uniform circuit-level noise model from one physical error rate.""" + p = _validate_probability("physical_error_rate", physical_error_rate) + return NoiseModel(p1=p, p2=p, p_meas=p, p_prep=p) + @property def is_noiseless(self) -> bool: """True if all error rates are zero.""" @@ -747,6 +762,63 @@ def _build_surface_tick_circuit_for_native_model( return traced_tc +def build_memory_circuit( + *, + rounds: int, + distance: int | None = None, + patch: SurfacePatch | None = None, + basis: str = "Z", + ancilla_budget: int | None = None, + circuit_source: Literal["abstract", "traced_qis"] = "abstract", +) -> Any: + """Build the standard surface-code memory ``TickCircuit``. + + This is the public, friendly entry point for the circuit used by PECOS's + native DEM, sampler, and decoder helpers. + + Args: + rounds: Number of syndrome-extraction rounds. + distance: Rotated surface-code distance. Provide either ``distance`` + or ``patch``. + patch: Explicit surface-code patch. Provide either ``patch`` or + ``distance``. + basis: Memory basis, ``"Z"`` or ``"X"``. + ancilla_budget: Optional cap on simultaneously live ancillas. + circuit_source: ``"abstract"`` for the native surface builder or + ``"traced_qis"`` for the lowered traced QIS gate stream. + + Returns: + A Rust-backed ``TickCircuit`` with detector and observable metadata. + + Example: + >>> from pecos.qec.surface import build_memory_circuit + >>> tc = build_memory_circuit(distance=3, rounds=3, basis="Z") + >>> int(tc.get_meta("num_measurements")) > 0 + True + """ + from pecos.qec.surface.patch import SurfacePatch + + if rounds < 1: + msg = f"rounds must be >= 1, got {rounds}" + raise ValueError(msg) + if patch is None: + if distance is None: + msg = "build_memory_circuit requires either distance=... or patch=..." + raise ValueError(msg) + patch = SurfacePatch.create(distance=distance) + elif distance is not None: + msg = "build_memory_circuit accepts either distance=... or patch=..., not both" + raise ValueError(msg) + + return _build_surface_tick_circuit_for_native_model( + patch, + rounds, + basis, + ancilla_budget=ancilla_budget, + circuit_source=circuit_source, + ) + + def _can_use_cached_surface_topology( *, ancilla_budget: int | None, @@ -2381,6 +2453,107 @@ class SimulationResult: decoder_type: str | None = None +def _memory_noise_model( + physical_error_rate: float | None, + noise_model: NoiseModel | None, +) -> NoiseModel: + """Resolve the surface-memory noise inputs into an explicit NoiseModel.""" + if noise_model is not None: + if physical_error_rate is not None: + msg = "pass either physical_error_rate or noise_model, not both" + raise ValueError(msg) + return noise_model + p = 0.001 if physical_error_rate is None else physical_error_rate + return NoiseModel.uniform(p) + + +def surface_code_memory( + *, + distance: int = 3, + physical_error_rate: float | None = None, + noise_model: NoiseModel | None = None, + shots: int = 1000, + rounds: int | None = None, + basis: str = "Z", + decoder_type: str = "pymatching", + seed: int | None = None, + decode: bool = True, + circuit_source: Literal["abstract", "traced_qis"] = "abstract", + ancilla_budget: int | None = None, +) -> SimulationResult: + """Run the recommended native surface-code memory workflow. + + This helper keeps the quick-start path short while using PECOS's Rust-backed + circuit-level DEM sampler and decoder machinery internally. + + Args: + distance: Rotated surface-code distance. + physical_error_rate: Uniform physical error rate used for one-qubit + gates, two-qubit gates, measurements, and preparation. Defaults to + ``0.001`` when ``noise_model`` is not provided. + noise_model: Explicit circuit-level noise model. Mutually exclusive + with ``physical_error_rate``. + shots: Number of Monte Carlo shots. + rounds: Number of syndrome-extraction rounds. Defaults to ``distance``. + basis: Memory basis, ``"Z"`` or ``"X"``. + decoder_type: Decoder backend passed to ``SampleBatch.decode_count``. + seed: Optional sampler seed. + decode: If false, report the raw observable-flip rate. + circuit_source: ``"abstract"`` or ``"traced_qis"`` circuit source. + ancilla_budget: Optional cap on simultaneously live ancillas. + + Returns: + ``SimulationResult`` with logical and raw error counts/rates. + + Example: + >>> from pecos.qec.surface import surface_code_memory + >>> result = surface_code_memory(distance=3, physical_error_rate=0.0, shots=4, rounds=1) + >>> result.logical_error_rate + 0.0 + """ + from pecos.qec import ParsedDem + from pecos.qec.surface.patch import SurfacePatch + + if distance < 1: + msg = f"distance must be >= 1, got {distance}" + raise ValueError(msg) + if shots < 0: + msg = f"shots must be >= 0, got {shots}" + raise ValueError(msg) + num_rounds = distance if rounds is None else rounds + if num_rounds < 1: + msg = f"rounds must be >= 1, got {num_rounds}" + raise ValueError(msg) + + noise_model = _memory_noise_model(physical_error_rate, noise_model) + patch = SurfacePatch.create(distance=distance) + dem = generate_circuit_level_dem_from_builder( + patch, + num_rounds=num_rounds, + noise=noise_model, + basis=basis, + decompose_errors=True, + ancilla_budget=ancilla_budget, + circuit_source=circuit_source, + ) + batch = ParsedDem.from_string(dem).to_dem_sampler().generate_samples(shots, seed) + num_raw_errors = sum(1 for shot in range(shots) if batch.get_observable_mask(shot) != 0) + num_logical_errors = batch.decode_count(dem, decoder_type) if decode else num_raw_errors + + return SimulationResult( + distance=distance, + num_shots=shots, + num_rounds=num_rounds, + basis=basis, + num_logical_errors=num_logical_errors, + num_raw_errors=num_raw_errors, + logical_error_rate=num_logical_errors / shots if shots else 0.0, + raw_error_rate=num_raw_errors / shots if shots else 0.0, + decoded=decode, + decoder_type=decoder_type if decode else None, + ) + + def run_noisy_memory_experiment( distance: int, num_rounds: int, diff --git a/python/quantum-pecos/tests/qec/test_qec_ux_entrypoints.py b/python/quantum-pecos/tests/qec/test_qec_ux_entrypoints.py new file mode 100644 index 000000000..435603e54 --- /dev/null +++ b/python/quantum-pecos/tests/qec/test_qec_ux_entrypoints.py @@ -0,0 +1,106 @@ +"""User-facing QEC entry point and metadata ergonomics tests.""" + +from __future__ import annotations + +import json + +import pytest + + +def test_main_pecos_namespace_exports_sim_neo_stack() -> None: + from pecos import depolarizing, fault_catalog, meas_sampling, sim_neo, stabilizer + from pecos.quantum import TickCircuit + + tc = TickCircuit() + tc.tick().mz([0]) + + result = sim_neo(tc).quantum(stabilizer()).noise(depolarizing()).shots(2).seed(123).run() + assert result.num_shots == 2 + assert meas_sampling() is not None + assert callable(fault_catalog) + + +def test_build_memory_circuit_is_public_surface_helper() -> None: + from pecos.qec.surface import build_memory_circuit + + tc = build_memory_circuit(distance=3, rounds=2, basis="Z") + + assert int(tc.get_meta("num_measurements")) > 0 + assert json.loads(tc.get_meta("detectors")) + assert json.loads(tc.get_meta("observables")) + + +def test_surface_code_memory_runs_native_zero_noise_quick_start() -> None: + from pecos.qec.surface import surface_code_memory + + result = surface_code_memory( + distance=3, + physical_error_rate=0.0, + shots=4, + rounds=1, + seed=123, + ) + + assert result.distance == 3 + assert result.num_shots == 4 + assert result.num_rounds == 1 + assert result.logical_error_rate == 0.0 + assert result.raw_error_rate == 0.0 + + +def test_surface_code_memory_rejects_ambiguous_noise_inputs() -> None: + from pecos.qec.surface import NoiseModel, surface_code_memory + + with pytest.raises(ValueError, match="either physical_error_rate or noise_model"): + surface_code_memory( + physical_error_rate=0.0, + noise_model=NoiseModel.uniform(0.001), + shots=0, + rounds=1, + ) + + +def test_tick_circuit_metadata_helpers_build_detector_and_observable_json() -> None: + from pecos.quantum import TickCircuit + + tc = TickCircuit() + det_id = tc.add_detector(records=[-1], coords=[0.0, 1.0, 2.0], label="d0") + obs_id = tc.add_observable(records=[-1, -2], label="L2") + + detectors = json.loads(tc.get_meta("detectors")) + observables = json.loads(tc.get_meta("observables")) + + assert det_id == 0 + assert detectors == [{"id": 0, "records": [-1], "coords": [0.0, 1.0, 2.0], "label": "d0"}] + assert int(tc.get_meta("num_detectors")) == 1 + + assert obs_id == 2 + assert observables == [{"id": 2, "records": [-1, -2], "label": "L2"}] + assert int(tc.get_meta("num_observables")) == 3 + + +def test_tick_circuit_observable_helper_rejects_conflicting_label_id() -> None: + from pecos.quantum import TickCircuit + + tc = TickCircuit() + with pytest.raises(ValueError, match="conflicts"): + tc.add_observable(records=[-1], observable_id=1, label="L2") + + +def test_tick_circuit_reset_clears_annotations_and_measurement_records() -> None: + from pecos.quantum import TickCircuit, Z + + tc = TickCircuit() + measurements = tc.tick().mz([0]) + tc.detector(measurements) + tc.observable(measurements) + tc.tracked_operator(Z(0)) + + assert tc.num_measurements() == 1 + assert len(tc.annotations()) == 3 + + tc.reset() + + assert tc.num_ticks() == 0 + assert tc.num_measurements() == 0 + assert tc.annotations() == [] diff --git a/uv.lock b/uv.lock index ec8023b9d..eabd7fb44 100644 --- a/uv.lock +++ b/uv.lock @@ -3916,6 +3916,7 @@ dependencies = [ { name = "networkx", version = "3.4.2", source = { registry = "https://pypi.org/simple" }, marker = "python_full_version < '3.11'" }, { name = "networkx", version = "3.6.1", source = { registry = "https://pypi.org/simple" }, marker = "python_full_version >= '3.11'" }, { name = "pecos-rslib" }, + { name = "pecos-rslib-exp" }, { name = "pecos-rslib-llvm" }, { name = "phir" }, { name = "selene-sim" }, @@ -3952,6 +3953,7 @@ requires-dist = [ { name = "networkx", specifier = ">=2.1.0" }, { name = "pecos-rslib", editable = "python/pecos-rslib" }, { name = "pecos-rslib-cuda", marker = "extra == 'cuda'", editable = "python/pecos-rslib-cuda" }, + { name = "pecos-rslib-exp", editable = "python/pecos-rslib-exp" }, { name = "pecos-rslib-llvm", editable = "python/pecos-rslib-llvm" }, { name = "phir", specifier = ">=0.3.3" }, { name = "plotly", marker = "extra == 'visualization'", specifier = "~=5.9.0" }, From a55391e3cd4663a4f839895fef36c1a959f2be34 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 00:10:07 -0600 Subject: [PATCH 099/125] Refine operator algebra and quantum-info validation --- crates/pecos-core/src/channel.rs | 31 + crates/pecos-core/src/clifford.rs | 6 + crates/pecos-core/src/clifford_rep.rs | 104 + crates/pecos-core/src/gate.rs | 81 + crates/pecos-core/src/gate_type.rs | 35 + crates/pecos-core/src/gates.rs | 285 ++- crates/pecos-core/src/lib.rs | 1 + crates/pecos-core/src/op.rs | 301 ++- crates/pecos-core/src/pauli/algebra.rs | 15 +- crates/pecos-core/src/qubit_support.rs | 82 + crates/pecos-core/src/unitary_rep.rs | 353 +++- .../pecos-engines/src/byte_message/builder.rs | 12 + .../pecos-engines/src/byte_message/message.rs | 41 +- .../src/fault_tolerance/circuit_runner.rs | 13 +- .../fault_tolerance/dem_builder/builder.rs | 60 + .../dem_builder/dem_sampler.rs | 19 + .../src/fault_tolerance/fault_sampler.rs | 243 +++ .../src/fault_tolerance/gadget_checker.rs | 6 +- .../src/fault_tolerance/influence_builder.rs | 11 +- .../src/fault_tolerance/pauli_prop_checker.rs | 12 +- crates/pecos-quantum/src/channel.rs | 440 ++++- crates/pecos-quantum/src/dag_circuit.rs | 107 +- crates/pecos-quantum/src/diamond_norm.rs | 18 + crates/pecos-quantum/src/lib.rs | 4 +- crates/pecos-quantum/src/measures.rs | 152 +- crates/pecos-quantum/src/pass.rs | 169 +- crates/pecos-quantum/src/pauli_sequence.rs | 18 + crates/pecos-quantum/src/tick_circuit.rs | 1678 +++++++++++++++-- crates/pecos-quantum/src/tick_circuit_soa.rs | 120 +- crates/pecos-quantum/src/unitary_matrix.rs | 54 + .../src/bitmask_pauli_prop.rs | 259 +++ crates/pecos-simulators/src/density_matrix.rs | 35 + crates/pecos-simulators/src/state_access.rs | 85 +- crates/pecos/src/lib.rs | 2 +- docs/user-guide/circuit-representation.md | 8 +- docs/user-guide/quantum-operator-algebra.md | 4 +- .../pecos-rslib/src/dag_circuit_bindings.rs | 100 +- python/pecos-rslib/src/pauli_bindings.rs | 35 +- .../tests/docs/rust_crate/Cargo.lock | 1 + .../user_guide_circuit_representation.rs | 6 +- .../user_guide_quantum_operator_algebra.rs | 4 +- .../tests/pecos/test_pauli_string_bindings.py | 63 +- .../tests/pecos/test_quantum_info_bindings.py | 112 ++ 43 files changed, 4709 insertions(+), 476 deletions(-) create mode 100644 crates/pecos-core/src/qubit_support.rs diff --git a/crates/pecos-core/src/channel.rs b/crates/pecos-core/src/channel.rs index 652d8464c..8109b0766 100644 --- a/crates/pecos-core/src/channel.rs +++ b/crates/pecos-core/src/channel.rs @@ -26,6 +26,7 @@ //! channel-level expression is needed. use crate::op::Op; +use crate::qubit_support::overlapping_qubits; use crate::{GateExpr, PauliString, QubitId, UnitaryRep, op}; use std::ops::{BitAnd, Mul}; @@ -139,6 +140,11 @@ impl BitAnd for ChannelExpr { type Output = ChannelExpr; fn bitand(self, rhs: ChannelExpr) -> ChannelExpr { + let overlap = overlapping_qubits(self.qubits(), rhs.qubits()); + assert!( + overlap.is_empty(), + "tensor product requires disjoint channel support; overlapping qubits: {overlap:?}" + ); ChannelExpr::Tensor(vec![self, rhs]) } } @@ -262,6 +268,12 @@ mod tests { assert!(matches!(Leakage(0.1, 0), ChannelExpr::Leakage { .. })); } + #[test] + #[should_panic(expected = "Depolarizing2 requires distinct qubits")] + fn channel_namespace_two_qubit_channel_rejects_repeated_qubit() { + let _ = Depolarizing2(0.1, 0, 0); + } + #[test] fn ideal_gate_lifts_to_channel_expr() { let channel = from_gate(gate::MZ(0)); @@ -280,6 +292,25 @@ mod tests { assert!(matches!(sequence, ChannelExpr::Compose(parts) if parts.len() == 2)); } + #[test] + #[should_panic(expected = "tensor product requires disjoint channel support")] + fn channel_tensor_rejects_overlapping_qubits() { + let _ = Depolarizing(0.1, 0) & BitFlip(0.2, 0); + } + + #[test] + #[should_panic(expected = "tensor product requires disjoint channel support")] + fn channel_tensor_rejects_partial_overlap_with_multi_qubit_support() { + let _ = Depolarizing2(0.1, 0, 2) & BitFlip(0.2, 2); + } + + #[test] + fn channel_tensor_uses_sparse_support_not_dense_span() { + let tensor = Depolarizing2(0.1, 0, 2) & BitFlip(0.2, 1); + assert!(matches!(tensor, ChannelExpr::Tensor(ref parts) if parts.len() == 2)); + assert_eq!(tensor.qubits(), vec![0, 1, 2]); + } + #[test] fn gate_channel_combinations_promote_to_channel_level() { let tensor = gate::H(0) & Depolarizing(0.1, 1); diff --git a/crates/pecos-core/src/clifford.rs b/crates/pecos-core/src/clifford.rs index a5817d756..a92cd72f3 100644 --- a/crates/pecos-core/src/clifford.rs +++ b/crates/pecos-core/src/clifford.rs @@ -985,6 +985,12 @@ mod tests { } } + #[test] + #[should_panic(expected = "SWAP requires distinct qubits")] + fn test_2q_on_qubits_rejects_repeated_qubit() { + let _ = Clifford::SWAP.on_qubits(0, 0); + } + #[test] fn test_on_qubits_noncontiguous() { let rep = Clifford::CX.on_qubits(0, 3); diff --git a/crates/pecos-core/src/clifford_rep.rs b/crates/pecos-core/src/clifford_rep.rs index ca7770684..efb7bb4f5 100644 --- a/crates/pecos-core/src/clifford_rep.rs +++ b/crates/pecos-core/src/clifford_rep.rs @@ -29,6 +29,7 @@ //! ``` use crate::pauli::algebra::i; +use crate::qubit_support::{assert_distinct_qubits, overlapping_qubits}; use crate::unitary_rep::UnitaryRep; use crate::{Pauli, PauliString, Phase, QuarterPhase}; use rand::RngExt; @@ -70,6 +71,27 @@ impl CliffordRep { self.num_qubits } + /// Returns qubits where this Clifford acts non-trivially. + /// + /// This is the operator support, not the tableau span. Identity action on + /// spectator qubits is omitted. + #[must_use] + pub fn support_qubits(&self) -> Vec { + let mut support = Vec::new(); + for q in 0..self.num_qubits { + let x_image = self.x_image(q); + let z_image = self.z_image(q); + if *x_image != PauliString::x(q) || *z_image != PauliString::z(q) { + support.push(q); + support.extend(x_image.qubits()); + support.extend(z_image.qubits()); + } + } + support.sort_unstable(); + support.dedup(); + support + } + /// Returns how X on the given qubit transforms. #[must_use] pub fn x_image(&self, qubit: usize) -> &PauliString { @@ -551,6 +573,7 @@ impl CliffordRep { /// `X_t` -> `X_t`, `Z_t` -> `Z_c` `Z_t` #[must_use] pub fn cx(control: usize, target: usize) -> Self { + assert_distinct_qubits("CX", [control, target]); let num_qubits = control.max(target) + 1; let mut cliff = Self::identity(num_qubits); @@ -569,6 +592,7 @@ impl CliffordRep { /// `X_1` -> `Z_0` `X_1`, `Z_1` -> `Z_1` #[must_use] pub fn cz(q0: usize, q1: usize) -> Self { + assert_distinct_qubits("CZ", [q0, q1]); let num_qubits = q0.max(q1) + 1; let mut cliff = Self::identity(num_qubits); @@ -587,6 +611,7 @@ impl CliffordRep { /// `X_1` -> `X_0`, `Z_1` -> `Z_0` #[must_use] pub fn swap(q0: usize, q1: usize) -> Self { + assert_distinct_qubits("SWAP", [q0, q1]); let num_qubits = q0.max(q1) + 1; let mut cliff = Self::identity(num_qubits); @@ -606,6 +631,7 @@ impl CliffordRep { /// `X_t` -> `Z_c` `X_t`, `Z_t` -> `Z_c` `Z_t` #[must_use] pub fn cy(control: usize, target: usize) -> Self { + assert_distinct_qubits("CY", [control, target]); let num_qubits = control.max(target) + 1; let mut cliff = Self::identity(num_qubits); @@ -624,6 +650,7 @@ impl CliffordRep { /// SXX gate (sqrt XX): XI -> XI, IX -> IX, ZI -> -YX, IZ -> -XY #[must_use] pub fn sxx(q0: usize, q1: usize) -> Self { + assert_distinct_qubits("SXX", [q0, q1]); let num_qubits = q0.max(q1) + 1; let mut cliff = Self::identity(num_qubits); cliff.z_images[q0] = -(PauliString::y(q0) & PauliString::x(q1)); @@ -634,6 +661,7 @@ impl CliffordRep { /// SXX† gate: XI -> XI, IX -> IX, ZI -> YX, IZ -> XY #[must_use] pub fn sxxdg(q0: usize, q1: usize) -> Self { + assert_distinct_qubits("SXXdg", [q0, q1]); let num_qubits = q0.max(q1) + 1; let mut cliff = Self::identity(num_qubits); cliff.z_images[q0] = PauliString::y(q0) & PauliString::x(q1); @@ -644,6 +672,7 @@ impl CliffordRep { /// SYY gate (sqrt YY): XI -> -ZY, IX -> -YZ, ZI -> XY, IZ -> YX #[must_use] pub fn syy(q0: usize, q1: usize) -> Self { + assert_distinct_qubits("SYY", [q0, q1]); let num_qubits = q0.max(q1) + 1; let mut cliff = Self::identity(num_qubits); cliff.x_images[q0] = -(PauliString::z(q0) & PauliString::y(q1)); @@ -656,6 +685,7 @@ impl CliffordRep { /// SYY† gate: XI -> ZY, IX -> YZ, ZI -> -XY, IZ -> -YX #[must_use] pub fn syydg(q0: usize, q1: usize) -> Self { + assert_distinct_qubits("SYYdg", [q0, q1]); let num_qubits = q0.max(q1) + 1; let mut cliff = Self::identity(num_qubits); cliff.x_images[q0] = PauliString::z(q0) & PauliString::y(q1); @@ -668,6 +698,7 @@ impl CliffordRep { /// SZZ gate (sqrt ZZ): XI -> YZ, IX -> ZY, ZI -> ZI, IZ -> IZ #[must_use] pub fn szz(q0: usize, q1: usize) -> Self { + assert_distinct_qubits("SZZ", [q0, q1]); let num_qubits = q0.max(q1) + 1; let mut cliff = Self::identity(num_qubits); cliff.x_images[q0] = PauliString::y(q0) & PauliString::z(q1); @@ -678,6 +709,7 @@ impl CliffordRep { /// SZZ† gate: XI -> -YZ, IX -> -ZY, ZI -> ZI, IZ -> IZ #[must_use] pub fn szzdg(q0: usize, q1: usize) -> Self { + assert_distinct_qubits("SZZdg", [q0, q1]); let num_qubits = q0.max(q1) + 1; let mut cliff = Self::identity(num_qubits); cliff.x_images[q0] = -(PauliString::y(q0) & PauliString::z(q1)); @@ -688,6 +720,7 @@ impl CliffordRep { /// iSWAP gate: XI -> ZY, IX -> YZ, ZI -> IZ, IZ -> ZI #[must_use] pub fn iswap(q0: usize, q1: usize) -> Self { + assert_distinct_qubits("ISWAP", [q0, q1]); let num_qubits = q0.max(q1) + 1; let mut cliff = Self::identity(num_qubits); cliff.x_images[q0] = PauliString::z(q0) & PauliString::y(q1); @@ -700,6 +733,7 @@ impl CliffordRep { /// G gate: XI -> IX, IX -> XI, ZI -> XZ, IZ -> ZX #[must_use] pub fn g(q0: usize, q1: usize) -> Self { + assert_distinct_qubits("G", [q0, q1]); let num_qubits = q0.max(q1) + 1; let mut cliff = Self::identity(num_qubits); cliff.x_images[q0] = PauliString::x(q1); @@ -714,6 +748,7 @@ impl CliffordRep { /// Both X images have opposite signs from iSWAP (the Z images are the same). #[must_use] pub fn iswapdg(q0: usize, q1: usize) -> Self { + assert_distinct_qubits("ISWAPdg", [q0, q1]); let num_qubits = q0.max(q1) + 1; let mut cliff = Self::identity(num_qubits); cliff.x_images[q0] = -(PauliString::z(q0) & PauliString::y(q1)); @@ -889,11 +924,22 @@ impl Mul<&CliffordRep> for &CliffordRep { // --- BitAnd trait: & operator for tensor product --- +fn assert_disjoint_clifford_support(lhs: &CliffordRep, rhs: &CliffordRep) { + let lhs_support = lhs.support_qubits(); + let rhs_support = rhs.support_qubits(); + let overlap = overlapping_qubits(lhs_support, rhs_support); + assert!( + overlap.is_empty(), + "tensor product requires disjoint Clifford support; overlapping qubits: {overlap:?}" + ); +} + impl BitAnd for CliffordRep { type Output = CliffordRep; /// Tensor product of two `CliffordReps` acting on disjoint qubits. fn bitand(self, rhs: CliffordRep) -> CliffordRep { + assert_disjoint_clifford_support(&self, &rhs); // Since compose auto-extends with identity on extra qubits, // and these CliffordReps act on disjoint qubits, composing gives the tensor. self.compose(&rhs) @@ -904,6 +950,7 @@ impl BitAnd<&CliffordRep> for CliffordRep { type Output = CliffordRep; fn bitand(self, rhs: &CliffordRep) -> CliffordRep { + assert_disjoint_clifford_support(&self, rhs); self.compose(rhs) } } @@ -912,6 +959,7 @@ impl BitAnd for &CliffordRep { type Output = CliffordRep; fn bitand(self, rhs: CliffordRep) -> CliffordRep { + assert_disjoint_clifford_support(self, &rhs); self.compose(&rhs) } } @@ -920,6 +968,7 @@ impl BitAnd<&CliffordRep> for &CliffordRep { type Output = CliffordRep; fn bitand(self, rhs: &CliffordRep) -> CliffordRep { + assert_disjoint_clifford_support(self, rhs); self.compose(rhs) } } @@ -1879,6 +1928,61 @@ mod tests { assert_eq!(cliff.apply(&z1), composed.apply(&z1)); } + #[test] + fn clifford_tensor_accepts_disjoint_support() { + let tensor = CliffordRep::h(0) & CliffordRep::sz(1); + + assert_eq!(tensor.apply(&PauliString::x(0)), PauliString::z(0)); + assert_eq!(tensor.apply(&PauliString::z(0)), PauliString::x(0)); + assert_eq!(tensor.apply(&PauliString::x(1)), PauliString::y(1)); + assert_eq!(tensor.apply(&PauliString::z(1)), PauliString::z(1)); + } + + #[test] + #[should_panic(expected = "tensor product requires disjoint Clifford support")] + fn clifford_tensor_rejects_overlapping_support() { + let _ = CliffordRep::h(0) & CliffordRep::sz(0); + } + + #[test] + fn support_qubits_omits_identity_spectators() { + assert!(CliffordRep::identity(10).support_qubits().is_empty()); + assert_eq!(CliffordRep::h(3).extended_to(10).support_qubits(), vec![3]); + assert_eq!( + CliffordRep::cx(0, 2).extended_to(5).support_qubits(), + vec![0, 2] + ); + } + + #[test] + fn clifford_tensor_accepts_interleaved_disjoint_support() { + let tensor = CliffordRep::cx(0, 2) & CliffordRep::h(1); + + assert!(tensor.is_valid()); + assert_eq!(tensor.support_qubits(), vec![0, 1, 2]); + assert_eq!( + tensor.apply(&PauliString::x(0)), + PauliString::x(0) & PauliString::x(2) + ); + assert_eq!( + tensor.apply(&PauliString::z(2)), + PauliString::z(0) & PauliString::z(2) + ); + assert_eq!(tensor.apply(&PauliString::x(1)), PauliString::z(1)); + } + + #[test] + #[should_panic(expected = "tensor product requires disjoint Clifford support")] + fn clifford_tensor_rejects_nonadjacent_partial_overlap() { + let _ = CliffordRep::cx(0, 2) & CliffordRep::z(2); + } + + #[test] + #[should_panic(expected = "SWAP requires distinct qubits")] + fn clifford_two_qubit_gate_rejects_repeated_qubit() { + let _ = CliffordRep::swap(2, 2); + } + #[test] fn test_clifford_enum_on_qubit() { use crate::clifford::Clifford; diff --git a/crates/pecos-core/src/gate.rs b/crates/pecos-core/src/gate.rs index 5db52bcea..985c0cff3 100644 --- a/crates/pecos-core/src/gate.rs +++ b/crates/pecos-core/src/gate.rs @@ -27,6 +27,7 @@ //! noise and open-system maps, use [`crate::channel`]. use crate::op::Op; +use crate::qubit_support::overlapping_qubits; use crate::unitary_rep::{QubitPairs, Qubits}; use crate::{Angle64, PauliString, QubitId, UnitaryRep, op, unitary_rep}; use std::ops::{BitAnd, Mul}; @@ -343,6 +344,11 @@ impl BitAnd for GateExpr { type Output = GateExpr; fn bitand(self, rhs: GateExpr) -> GateExpr { + let overlap = overlapping_qubits(self.qubits(), rhs.qubits()); + assert!( + overlap.is_empty(), + "tensor product requires disjoint gate support; overlapping qubits: {overlap:?}" + ); GateExpr::Tensor(vec![self, rhs]) } } @@ -461,6 +467,24 @@ mod tests { assert_eq!(I(7).qubits(), vec![7]); } + #[test] + #[should_panic(expected = "CX requires distinct qubits")] + fn gate_namespace_two_qubit_gate_rejects_repeated_qubit() { + let _ = CX(0, 0); + } + + #[test] + #[should_panic(expected = "RZZ requires distinct qubits")] + fn gate_namespace_two_qubit_rotation_rejects_repeated_qubit() { + let _ = RZZ(Angle64::QUARTER_TURN, 1, 1); + } + + #[test] + #[should_panic(expected = "CCX requires distinct qubits")] + fn gate_namespace_three_qubit_gate_rejects_repeated_qubit() { + let _ = CCX(0, 1, 1); + } + #[test] fn gate_tensor_and_composition_stay_gate_level() { let tensor = H(0) & MZ(1); @@ -469,4 +493,61 @@ mod tests { let sequence = PZ(0) * H(0) * MZ(0); assert!(matches!(sequence, GateExpr::Compose(parts) if parts.len() == 2)); } + + #[test] + #[should_panic(expected = "tensor product requires disjoint gate support")] + fn gate_tensor_rejects_overlapping_qubits() { + let _ = H(0) & MZ(0); + } + + #[test] + #[should_panic(expected = "tensor product requires disjoint gate support")] + fn gate_tensor_rejects_partial_overlap_with_multi_qubit_support() { + let _ = CX(0, 2) & H(2); + } + + #[test] + fn gate_tensor_uses_sparse_support_not_dense_span() { + let tensor = CX(0, 2) & MZ(1); + assert!(matches!(tensor, GateExpr::Tensor(ref parts) if parts.len() == 2)); + assert_eq!(tensor.qubits(), vec![0, 1, 2]); + } + + #[test] + fn gate_namespace_plural_helpers_match_tensor_forms() { + let cxs = CXs([(0, 1), (2, 3)]); + assert!(matches!(cxs, GateExpr::Unitary(_))); + assert_eq!(cxs.qubits(), vec![0, 1, 2, 3]); + + let rzzs = RZZs(Angle64::QUARTER_TURN, [(0, 1), (2, 3)]); + assert!(matches!(rzzs, GateExpr::Unitary(_))); + assert_eq!(rzzs.qubits(), vec![0, 1, 2, 3]); + + let tensor = CX(0, 1) & CX(2, 3); + assert!(matches!(tensor, GateExpr::Tensor(_))); + assert_eq!(tensor.qubits(), vec![0, 1, 2, 3]); + } + + #[test] + fn gate_namespace_plural_helpers_reject_overlapping_support() { + fn assert_tensor_overlap_panic(f: impl FnOnce() + std::panic::UnwindSafe) { + let err = std::panic::catch_unwind(f).expect_err("expected tensor overlap panic"); + let message = err + .downcast_ref::() + .map(String::as_str) + .or_else(|| err.downcast_ref::<&str>().copied()) + .unwrap_or(""); + assert!( + message.contains("tensor product requires disjoint"), + "unexpected panic message: {message}" + ); + } + + assert_tensor_overlap_panic(|| { + let _ = CXs([(0, 1), (1, 2)]); + }); + assert_tensor_overlap_panic(|| { + let _ = RZZs(Angle64::QUARTER_TURN, [(0, 2), (2, 3)]); + }); + } } diff --git a/crates/pecos-core/src/gate_type.rs b/crates/pecos-core/src/gate_type.rs index d191e149c..52f140fe2 100644 --- a/crates/pecos-core/src/gate_type.rs +++ b/crates/pecos-core/src/gate_type.rs @@ -338,6 +338,29 @@ impl GateType { } } + /// Returns the number of gates represented by a command with `qubit_count` + /// qubits. + /// + /// Most gate commands are batchable: a command with 4 qubits and arity 2 + /// represents two gates. Payload/meta gates are annotations, not physical + /// gates. Variable-arity custom/channel gates are counted as one + /// command-level gate. + #[must_use] + pub const fn num_gates(self, qubit_count: usize) -> usize { + if matches!( + self, + GateType::MeasCrosstalkGlobalPayload + | GateType::MeasCrosstalkLocalPayload + | GateType::PauliOperatorMeta + ) { + return 0; + } + if matches!(self, GateType::Custom | GateType::Channel) { + return 1; + } + qubit_count / self.quantum_arity() + } + /// Returns the number of angle parameters this gate type requires. /// /// This is separate from `classical_arity()` which includes all classical parameters. @@ -677,6 +700,18 @@ mod tests { assert_eq!(GateType::RZZ.quantum_arity(), 2); } + #[test] + fn test_num_gates() { + assert_eq!(GateType::H.num_gates(4), 4); + assert_eq!(GateType::CX.num_gates(4), 2); + assert_eq!(GateType::CCX.num_gates(6), 2); + assert_eq!(GateType::Custom.num_gates(2), 1); + assert_eq!(GateType::Channel.num_gates(2), 1); + assert_eq!(GateType::PauliOperatorMeta.num_gates(3), 0); + assert_eq!(GateType::MeasCrosstalkGlobalPayload.num_gates(3), 0); + assert_eq!(GateType::MeasCrosstalkLocalPayload.num_gates(3), 0); + } + #[test] fn test_is_parameterized() { // Non-parameterized gates diff --git a/crates/pecos-core/src/gates.rs b/crates/pecos-core/src/gates.rs index 0d329f2b9..188f30ce5 100644 --- a/crates/pecos-core/src/gates.rs +++ b/crates/pecos-core/src/gates.rs @@ -8,6 +8,7 @@ use crate::ChannelExpr; use crate::MeasId; use crate::QubitId; use crate::gate_type::GateType; +use crate::qubit_support::duplicate_qubits; use smallvec::SmallVec; /// Stack-allocated qubit buffer for gates (up to 4 qubits inline). @@ -116,7 +117,66 @@ impl Gate { #[inline] #[must_use] pub fn num_gates(&self) -> usize { - self.num_qubits() / self.quantum_arity() + self.gate_type.num_gates(self.num_qubits()) + } + + /// Returns true if `self` and `other` can be represented as one batched gate + /// command by concatenating qubit and measurement-id payloads. + /// + /// Batch-compatible gates are identical except for disjoint qubit support + /// and, for measurement gates, their corresponding measurement ids. + #[must_use] + pub fn can_batch_with(&self, other: &Self) -> bool { + if self.gate_type != other.gate_type + || self.angles != other.angles + || self.params != other.params + || self.channel != other.channel + { + return false; + } + + if matches!( + self.gate_type, + GateType::Custom + | GateType::Channel + | GateType::PauliOperatorMeta + | GateType::MeasCrosstalkGlobalPayload + | GateType::MeasCrosstalkLocalPayload + ) { + return false; + } + + if self.qubits.iter().any(|q| other.qubits.contains(q)) { + return false; + } + + let self_has_meas_ids = !self.meas_ids.is_empty(); + let other_has_meas_ids = !other.meas_ids.is_empty(); + if self_has_meas_ids != other_has_meas_ids { + return false; + } + if self_has_meas_ids + && (self.meas_ids.len() != self.qubits.len() + || other.meas_ids.len() != other.qubits.len()) + { + return false; + } + + true + } + + /// Appends a compatible gate command into this batch. + /// + /// # Panics + /// + /// Panics if `other` is not batch-compatible with `self`. + pub fn append_batch(&mut self, other: Self) { + assert!( + self.can_batch_with(&other), + "cannot batch incompatible gate commands" + ); + self.qubits.extend(other.qubits); + self.meas_ids.extend(other.meas_ids); } /// Helper function to flatten qubit pairs into a `GateQubits` buffer @@ -1037,6 +1097,7 @@ impl Gate { /// Returns an error if: /// - The number of angles doesn't match the gate's angle arity /// - The number of qubits is not a multiple of the gate's quantum arity + /// - Any qubit is repeated within the gate command pub fn validate(&self) -> Result<(), String> { if self.is_channel() { let Some(channel) = &self.channel else { @@ -1064,6 +1125,19 @@ impl Gate { if self.channel.is_some() { return Err("Only GateType::Channel can carry a channel payload".to_string()); } + if self.gate_type == GateType::Custom { + let duplicates = duplicate_qubits(self.qubits.iter().map(|q| q.0)); + if !duplicates.is_empty() { + return Err(format!( + "Gate {:?} requires distinct qubits within one gate command; duplicated qubits: {:?}", + self.gate_type, duplicates + )); + } + if !self.meas_ids.is_empty() { + return Err("Custom gates cannot carry measurement-id payloads".to_string()); + } + return Ok(()); + } // Check angle parameters if self.angles.len() != self.angle_arity() { return Err(format!( @@ -1082,6 +1156,41 @@ impl Gate { self.qubits.len() )); } + let expected_params = self.classical_arity() - self.angle_arity(); + if self.params.len() != expected_params { + return Err(format!( + "Gate {:?} expected {} non-angle parameters, got {}", + self.gate_type, + expected_params, + self.params.len() + )); + } + let duplicates = duplicate_qubits(self.qubits.iter().map(|q| q.0)); + if !duplicates.is_empty() { + return Err(format!( + "Gate {:?} requires distinct qubits within one gate command; duplicated qubits: {:?}", + self.gate_type, duplicates + )); + } + let is_measurement = matches!( + self.gate_type, + GateType::MZ | GateType::MeasureLeaked | GateType::MeasureFree + ); + if is_measurement { + if !self.meas_ids.is_empty() && self.meas_ids.len() != self.qubits.len() { + return Err(format!( + "Measurement gate {:?} expected measurement-id count to be 0 or {}, got {}", + self.gate_type, + self.qubits.len(), + self.meas_ids.len() + )); + } + } else if !self.meas_ids.is_empty() { + return Err(format!( + "Gate {:?} cannot carry measurement-id payloads", + self.gate_type + )); + } Ok(()) } } @@ -1151,10 +1260,66 @@ mod tests { &[QubitId::from(0), QubitId::from(1)] ); assert_eq!(two_qubit_gate.quantum_arity(), 2); + assert_eq!(two_qubit_gate.num_gates(), 1); assert!(two_qubit_gate.is_two_qubit()); assert!(two_qubit_gate.validate().is_ok()); } + #[test] + fn test_num_gates_counts_batched_gates() { + assert_eq!(Gate::h(&[0, 1, 2, 3]).num_gates(), 4); + assert_eq!(Gate::cx(&[(0, 1), (2, 3)]).num_gates(), 2); + assert_eq!(Gate::ccx(&[(0, 1, 2), (3, 4, 5)]).num_gates(), 2); + + assert_eq!( + Gate::custom(vec![QubitId::from(0), QubitId::from(1)]).num_gates(), + 1 + ); + assert_eq!( + Gate::simple( + GateType::PauliOperatorMeta, + vec![QubitId::from(0), QubitId::from(1)] + ) + .num_gates(), + 0 + ); + assert_eq!(Gate::meas_crosstalk_global_payload(&[0, 1]).num_gates(), 0); + } + + #[test] + fn test_gate_batch_compatibility_and_append() { + let mut h0 = Gate::h(&[0]); + let h1 = Gate::h(&[1]); + assert!(h0.can_batch_with(&h1)); + h0.append_batch(h1); + assert_eq!(h0.qubits.as_slice(), &[QubitId::from(0), QubitId::from(1)]); + assert_eq!(h0.num_gates(), 2); + + assert!(!Gate::h(&[0]).can_batch_with(&Gate::h(&[0]))); + assert!( + !Gate::rz(Angle64::from_turns(0.25), &[0]) + .can_batch_with(&Gate::rz(Angle64::from_turns(0.5), &[1])) + ); + assert!( + !Gate::custom(vec![QubitId::from(0)]) + .can_batch_with(&Gate::custom(vec![QubitId::from(1)])) + ); + } + + #[test] + fn test_measurement_batch_compatibility_preserves_measurement_ids() { + let mut m0 = Gate::mz(&[0]); + m0.meas_ids.push(MeasId(4)); + let mut m1 = Gate::mz(&[1]); + m1.meas_ids.push(MeasId(5)); + + assert!(m0.can_batch_with(&m1)); + m0.append_batch(m1); + + assert_eq!(m0.qubits.as_slice(), &[QubitId::from(0), QubitId::from(1)]); + assert_eq!(m0.meas_ids.as_slice(), &[MeasId(4), MeasId(5)]); + } + #[test] fn test_two_qubit_gate_vec_variants() { // Test CX with _vec variant - much more convenient when you have a flat list @@ -1193,6 +1358,45 @@ mod tests { let _ = Gate::cx_vec(&[0, 1, 2]); } + #[test] + fn test_gate_validate_rejects_repeated_qubits_within_pair() { + let err = Gate::cx(&[(0, 0)]).validate().unwrap_err(); + assert!(err.contains("requires distinct qubits")); + assert!(err.contains("[0]")); + } + + #[test] + fn test_gate_validate_rejects_repeated_qubits_across_batched_pairs() { + let err = Gate::swap(&[(0, 1), (1, 2)]).validate().unwrap_err(); + assert!(err.contains("requires distinct qubits")); + assert!(err.contains("[1]")); + } + + #[test] + fn test_gate_validate_rejects_repeated_qubits_in_three_qubit_gate() { + let err = Gate::ccx(&[(0, 1, 1)]).validate().unwrap_err(); + assert!(err.contains("requires distinct qubits")); + assert!(err.contains("[1]")); + } + + #[test] + fn test_gate_validate_rejects_repeated_qubits_in_parameterized_two_qubit_gates() { + let angle = Angle64::from_turns(0.25); + let kak_angles = [[Angle64::ZERO; 3]; 2]; + let interaction = [Angle64::ZERO; 3]; + + let cases = [ + Gate::rzz(angle, &[(2, 2)]), + Gate::rxxryyrzz(angle, angle, angle, &[(3, 3)]), + Gate::u2q(kak_angles, interaction, kak_angles, &[(4, 4)]), + ]; + + for gate in cases { + let err = gate.validate().unwrap_err(); + assert!(err.contains("requires distinct qubits"), "{err}"); + } + } + #[test] #[should_panic(expected = "SZZ gate requires an even number of qubits")] fn test_szz_vec_odd_qubits() { @@ -1405,4 +1609,83 @@ mod tests { ); assert!(multi_cx_gates.validate().is_ok()); // Multiple CX gates } + + #[test] + fn test_gate_validation_rejects_duplicate_qubits_for_batched_commands() { + let duplicate_x = Gate::x(&[0, 0]); + let err = duplicate_x.validate().unwrap_err(); + assert!(err.contains("requires distinct qubits")); + assert!(err.contains("[0]")); + + let duplicate_mz = Gate::mz(&[1, 1]); + let err = duplicate_mz.validate().unwrap_err(); + assert!(err.contains("requires distinct qubits")); + assert!(err.contains("[1]")); + } + + #[test] + fn test_gate_validation_checks_non_angle_parameters_and_measurement_ids() { + let missing_idle_duration = Gate::new( + GateType::Idle, + Vec::::new(), + Vec::::new(), + vec![QubitId::from(0)], + ); + assert!( + missing_idle_duration + .validate() + .unwrap_err() + .contains("expected 1 non-angle parameters, got 0") + ); + + let mut measured = Gate::mz(&[0, 1]); + measured.meas_ids.push(MeasId(0)); + assert!( + measured + .validate() + .unwrap_err() + .contains("expected measurement-id count to be 0 or 2, got 1") + ); + + let mut non_measurement = Gate::x(&[0]); + non_measurement.meas_ids.push(MeasId(0)); + assert!( + non_measurement + .validate() + .unwrap_err() + .contains("cannot carry measurement-id payloads") + ); + } + + #[test] + fn test_channel_gate_validation_rejects_stale_payloads() { + use crate::channel::{BitFlip, Depolarizing}; + + let mut stale_qubits = Gate::channel(Depolarizing(0.25, 0)); + stale_qubits.qubits = vec![QubitId::from(1)].into(); + assert!( + stale_qubits + .validate() + .unwrap_err() + .contains("do not match channel payload qubits") + ); + + let mut stale_angles = Gate::channel(BitFlip(0.1, 0)); + stale_angles.angles.push(Angle64::from_turns(0.25)); + assert!( + stale_angles + .validate() + .unwrap_err() + .contains("cannot carry angle, parameter, or measurement-id payloads") + ); + + let mut channel_payload_on_ideal_gate = Gate::x(&[0]); + channel_payload_on_ideal_gate.channel = Some(BitFlip(0.1, 0)); + assert!( + channel_payload_on_ideal_gate + .validate() + .unwrap_err() + .contains("Only GateType::Channel can carry a channel payload") + ); + } } diff --git a/crates/pecos-core/src/lib.rs b/crates/pecos-core/src/lib.rs index 800446a0f..68127d0d4 100644 --- a/crates/pecos-core/src/lib.rs +++ b/crates/pecos-core/src/lib.rs @@ -32,6 +32,7 @@ pub mod pauli; pub mod phase; pub mod prelude; pub mod qubit_id; +mod qubit_support; pub mod rng; pub mod sets; pub mod signal; diff --git a/crates/pecos-core/src/op.rs b/crates/pecos-core/src/op.rs index 15b8a66c8..0062d7c8e 100644 --- a/crates/pecos-core/src/op.rs +++ b/crates/pecos-core/src/op.rs @@ -54,6 +54,7 @@ //! ``` use crate::clifford_rep::CliffordRep; +use crate::qubit_support::{assert_distinct_qubits, overlapping_qubits}; use crate::unitary_rep::{PhaseValue, UnitaryRep}; use crate::{Angle64, PauliString, QubitId}; use std::fmt; @@ -95,6 +96,32 @@ pub enum Level { Channel = 4, } +/// Error returned by fallible tensor-product constructors when supports overlap. +#[derive(Debug, Clone, PartialEq, Eq)] +pub struct TensorProductError { + overlapping_qubits: Vec, +} + +impl TensorProductError { + /// Qubits touched by both operands. + #[must_use] + pub fn overlapping_qubits(&self) -> &[usize] { + &self.overlapping_qubits + } +} + +impl fmt::Display for TensorProductError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!( + f, + "tensor product requires disjoint operator support; overlapping qubits: {:?}", + self.overlapping_qubits + ) + } +} + +impl std::error::Error for TensorProductError {} + /// An ideal circuit operation expression. /// /// Gate expressions represent operations that can appear in an ideal circuit @@ -179,6 +206,15 @@ fn cliff(cr: CliffordRep, ur: UnitaryRep) -> Op { Op::Clifford(cr, ur) } +fn require_disjoint_support(lhs: &[usize], rhs: &[usize]) -> Result<(), TensorProductError> { + let overlapping_qubits = overlapping_qubits(lhs.iter().copied(), rhs.iter().copied()); + if overlapping_qubits.is_empty() { + Ok(()) + } else { + Err(TensorProductError { overlapping_qubits }) + } +} + // --- Core methods --- impl Op { @@ -355,6 +391,60 @@ impl Op { Op::Channel(self.into_channel()) } + /// Returns the tensor product of two operations. + /// + /// This is the fallible form of the `&` operator. Tensor products require + /// disjoint qubit support; use `*` for sequential composition on the same + /// qubits. + /// + /// # Errors + /// + /// Returns [`TensorProductError`] when the two operations touch any of the + /// same qubits. + pub fn try_tensor(self, rhs: Op) -> Result { + require_disjoint_support(&self.qubits(), &rhs.qubits())?; + Ok(self.tensor_unchecked(rhs)) + } + + fn tensor_unchecked(self, rhs: Op) -> Op { + let max_level = self.level().max(rhs.level()); + match max_level { + Level::Pauli => { + let a = self.into_pauli().expect("max_level is Pauli"); + let b = rhs.into_pauli().expect("max_level is Pauli"); + Op::Pauli(&a & &b) + } + Level::Clifford => { + let (cr_a, ur_a) = match self { + Op::Pauli(ps) => pauli_to_cliff_pair(ps), + Op::Clifford(cr, ur) => (cr, ur), + _ => unreachable!(), + }; + let (cr_b, ur_b) = match rhs { + Op::Pauli(ps) => pauli_to_cliff_pair(ps), + Op::Clifford(cr, ur) => (cr, ur), + _ => unreachable!(), + }; + cliff(cr_a.compose(&cr_b), ur_a & ur_b) + } + Level::Unitary => { + let a = self.into_unitary().expect("max_level is Unitary"); + let b = rhs.into_unitary().expect("max_level is Unitary"); + Op::Unitary(a & b) + } + Level::Gate => { + let a = self.into_gate().expect("max_level is Gate"); + let b = rhs.into_gate().expect("max_level is Gate"); + Op::Gate(GateExpr::Tensor(vec![a, b])) + } + Level::Channel => { + let a = self.into_channel(); + let b = rhs.into_channel(); + Op::Channel(ChannelExpr::Tensor(vec![a, b])) + } + } + } + /// Returns the adjoint (dagger) of this expression. /// /// # Panics @@ -386,7 +476,13 @@ impl Op { pub fn qubits(&self) -> Vec { match self { Op::Pauli(ps) => ps.qubits(), - Op::Clifford(cr, _) => (0..cr.num_qubits()).collect(), + Op::Clifford(cr, ur) => { + let mut qs = cr.support_qubits(); + qs.extend(ur.qubits()); + qs.sort_unstable(); + qs.dedup(); + qs + } Op::Unitary(ur) => ur.qubits(), Op::Gate(gate) => gate.qubits(), Op::Channel(ch) => ch.qubits(), @@ -569,42 +665,7 @@ impl BitAnd for Op { type Output = Op; fn bitand(self, rhs: Op) -> Op { - let max_level = self.level().max(rhs.level()); - match max_level { - Level::Pauli => { - let a = self.into_pauli().expect("max_level is Pauli"); - let b = rhs.into_pauli().expect("max_level is Pauli"); - Op::Pauli(&a & &b) - } - Level::Clifford => { - let (cr_a, ur_a) = match self { - Op::Pauli(ps) => pauli_to_cliff_pair(ps), - Op::Clifford(cr, ur) => (cr, ur), - _ => unreachable!(), - }; - let (cr_b, ur_b) = match rhs { - Op::Pauli(ps) => pauli_to_cliff_pair(ps), - Op::Clifford(cr, ur) => (cr, ur), - _ => unreachable!(), - }; - cliff(cr_a.compose(&cr_b), ur_a & ur_b) - } - Level::Unitary => { - let a = self.into_unitary().expect("max_level is Unitary"); - let b = rhs.into_unitary().expect("max_level is Unitary"); - Op::Unitary(a & b) - } - Level::Gate => { - let a = self.into_gate().expect("max_level is Gate"); - let b = rhs.into_gate().expect("max_level is Gate"); - Op::Gate(GateExpr::Tensor(vec![a, b])) - } - Level::Channel => { - let a = self.into_channel(); - let b = rhs.into_channel(); - Op::Channel(ChannelExpr::Tensor(vec![a, b])) - } - } + self.try_tensor(rhs).unwrap_or_else(|err| panic!("{err}")) } } @@ -1518,6 +1579,7 @@ pub fn Depolarizing2(p: f64, q0: impl Into, q1: impl Into) -> assert!((0.0..=1.0).contains(&p), "probability p must be in [0, 1]"); let a = q0.into(); let b = q1.into(); + assert_distinct_qubits("Depolarizing2", [a.0, b.0]); let p15 = p / 15.0; let paulis_1q = [ unitary_rep::I, @@ -1699,6 +1761,18 @@ mod tests { assert!(op.is_clifford()); } + #[test] + fn clifford_tensor_uses_actual_support_not_span() { + let op = H(0) & SZ(3); + let cr = op.as_clifford().unwrap(); + + assert_eq!(op.qubits(), vec![0, 3]); + assert_eq!(cr.apply(&PauliString::x(0)), PauliString::z(0)); + assert_eq!(cr.apply(&PauliString::z(0)), PauliString::x(0)); + assert_eq!(cr.apply(&PauliString::x(3)), PauliString::y(3)); + assert_eq!(cr.apply(&PauliString::z(3)), PauliString::z(3)); + } + #[test] fn pauli_unitary_tensor_promotes() { let op = X(0) & T(3); @@ -1717,6 +1791,131 @@ mod tests { assert!(op.is_unitary()); } + #[test] + fn try_tensor_reports_overlapping_qubits() { + let err = X(0).try_tensor(Z(0)).unwrap_err(); + assert_eq!(err.overlapping_qubits(), &[0]); + } + + #[test] + fn try_tensor_rejects_mixed_level_overlaps() { + let cases = [ + ("pauli-clifford", X(0), H(0), vec![0]), + ("pauli-unitary", X(0), T(0), vec![0]), + ("pauli-gate", X(0), MZ(0), vec![0]), + ("pauli-channel", X(0), Depolarizing(0.01, 0), vec![0]), + ("clifford-gate", H(0), MZ(0), vec![0]), + ("gate-channel", MZ(0), Depolarizing(0.01, 0), vec![0]), + ("partial-multi-qubit", CX(0, 2), H(2), vec![2]), + ]; + + for (name, lhs, rhs, expected_overlap) in cases { + let err = lhs.try_tensor(rhs).unwrap_err(); + assert_eq!( + err.overlapping_qubits(), + expected_overlap.as_slice(), + "{name}" + ); + } + } + + #[test] + fn tensor_operator_panics_are_consistent_across_levels() { + fn assert_overlap_panic(f: impl FnOnce() + std::panic::UnwindSafe, expected: &str) { + let err = std::panic::catch_unwind(f).expect_err("expected tensor overlap panic"); + let message = if let Some(message) = err.downcast_ref::() { + message.as_str() + } else if let Some(message) = err.downcast_ref::<&str>() { + message + } else { + panic!("unexpected non-string panic payload"); + }; + assert!( + message.contains("tensor product requires disjoint operator support"), + "{message}" + ); + assert!(message.contains(expected), "{message}"); + } + + assert_overlap_panic( + || { + let _ = X(0) & Z(0); + }, + "[0]", + ); + assert_overlap_panic( + || { + let _ = H(0) & T(0); + }, + "[0]", + ); + assert_overlap_panic( + || { + let _ = T(0) & MZ(0); + }, + "[0]", + ); + assert_overlap_panic( + || { + let _ = MZ(0) & Depolarizing(0.01, 0); + }, + "[0]", + ); + assert_overlap_panic( + || { + let _ = CX(0, 2) & Depolarizing(0.01, 2); + }, + "[2]", + ); + } + + #[test] + fn try_tensor_accepts_mixed_level_disjoint_support() { + assert!((X(0).try_tensor(H(1))).unwrap().is_clifford()); + assert!((H(0).try_tensor(T(1))).unwrap().is_unitary()); + assert!( + (MZ(0).try_tensor(Depolarizing(0.01, 1))) + .unwrap() + .is_channel() + ); + } + + #[test] + #[should_panic(expected = "tensor product requires disjoint operator support")] + fn pauli_tensor_rejects_overlapping_qubits() { + let _ = X(0) & Z(0); + } + + #[test] + #[should_panic(expected = "tensor product requires disjoint operator support")] + fn clifford_tensor_rejects_overlapping_qubits() { + let _ = H(0) & SZ(0); + } + + #[test] + #[should_panic(expected = "tensor product requires disjoint operator support")] + fn gate_tensor_rejects_overlapping_qubits() { + let _ = H(0) & MZ(0); + } + + #[test] + #[should_panic(expected = "tensor product requires disjoint operator support")] + fn channel_tensor_rejects_overlapping_qubits() { + let _ = H(0) & Depolarizing(0.01, 0); + } + + #[test] + #[should_panic(expected = "SWAP requires distinct qubits")] + fn op_two_qubit_gate_rejects_repeated_qubit() { + let _ = SWAP(0, 0); + } + + #[test] + #[should_panic(expected = "Depolarizing2 requires distinct qubits")] + fn op_two_qubit_channel_rejects_repeated_qubit() { + let _ = Depolarizing2(0.01, 2, 2); + } + // --- Composition promotion --- #[test] @@ -2112,6 +2311,13 @@ mod tests { assert!(op.is_gate()); } + #[test] + fn non_clifford_unitary_gate_tensor_promotes_to_gate_tensor() { + let op = T(0) & MZ(1); + assert!(op.is_gate()); + assert!(matches!(op, Op::Gate(GateExpr::Tensor(parts)) if parts.len() == 2)); + } + #[test] fn pauli_gate_tensor_promotes() { let op = X(0) & MZ(1); @@ -2124,6 +2330,13 @@ mod tests { assert!(op.is_gate()); } + #[test] + fn non_clifford_unitary_gate_compose_promotes_to_gate_compose() { + let op = T(0) * MZ(0); + assert!(op.is_gate()); + assert!(matches!(op, Op::Gate(GateExpr::Compose(parts)) if parts.len() == 2)); + } + #[test] fn into_channel_always_succeeds() { // All levels can promote to ChannelExpr @@ -2284,12 +2497,26 @@ mod tests { assert!(op.is_channel()); } + #[test] + fn non_clifford_unitary_channel_tensor_promotes_to_channel_tensor() { + let op = T(0) & Depolarizing(0.1, 1); + assert!(op.is_channel()); + assert!(matches!(op, Op::Channel(ChannelExpr::Tensor(parts)) if parts.len() == 2)); + } + #[test] fn noise_compose_with_gate() { let op = H(0) * Dephasing(0.05, 0); assert!(op.is_channel()); } + #[test] + fn non_clifford_unitary_channel_compose_promotes_to_channel_compose() { + let op = T(0) * Dephasing(0.05, 0); + assert!(op.is_channel()); + assert!(matches!(op, Op::Channel(ChannelExpr::Compose(parts)) if parts.len() == 2)); + } + #[test] fn mixed_unitary_qubits() { let op = Depolarizing(0.1, 5); diff --git a/crates/pecos-core/src/pauli/algebra.rs b/crates/pecos-core/src/pauli/algebra.rs index b859bf636..e038b56b7 100644 --- a/crates/pecos-core/src/pauli/algebra.rs +++ b/crates/pecos-core/src/pauli/algebra.rs @@ -45,6 +45,7 @@ //! let ps = -PauliString::x(0); // -X //! ``` +use crate::qubit_support::overlapping_qubits; use crate::{Pauli, PauliString, Phase, QuarterPhase, QubitId}; use std::ops::{BitAnd, Mul, Neg}; @@ -80,10 +81,16 @@ impl BitAnd for PauliString { type Output = PauliString; fn bitand(self, rhs: PauliString) -> PauliString { + let overlap = overlapping_qubits(self.qubits(), rhs.qubits()); + assert!( + overlap.is_empty(), + "tensor product requires disjoint Pauli support; overlapping qubits: {overlap:?}" + ); + // Combine phases let new_phase = self.phase().multiply(&rhs.phase()); - // Combine paulis (assuming no overlap - tensor product) + // Combine paulis. let mut paulis: Vec<(Pauli, QubitId)> = self.iter_pairs().collect(); paulis.extend(rhs.iter_pairs()); @@ -289,6 +296,12 @@ mod tests { assert_eq!(ps.weight(), 2); } + #[test] + #[should_panic(expected = "tensor product requires disjoint Pauli support")] + fn test_tensor_product_rejects_overlapping_qubits() { + let _ = PauliString::x(0) & PauliString::z(0); + } + #[test] fn test_triple_tensor() { let ps = PauliString::x(0) & PauliString::y(2) & PauliString::z(5); diff --git a/crates/pecos-core/src/qubit_support.rs b/crates/pecos-core/src/qubit_support.rs new file mode 100644 index 000000000..38dc41ce0 --- /dev/null +++ b/crates/pecos-core/src/qubit_support.rs @@ -0,0 +1,82 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +pub(crate) fn overlapping_qubits( + lhs: impl IntoIterator, + rhs: impl IntoIterator, +) -> Vec { + let mut lhs_qubits: Vec = lhs.into_iter().collect(); + lhs_qubits.sort_unstable(); + lhs_qubits.dedup(); + + let mut rhs_qubits: Vec = rhs.into_iter().collect(); + rhs_qubits.sort_unstable(); + rhs_qubits.dedup(); + + let mut overlap = Vec::new(); + let mut lhs_idx = 0; + let mut rhs_idx = 0; + while lhs_idx < lhs_qubits.len() && rhs_idx < rhs_qubits.len() { + match lhs_qubits[lhs_idx].cmp(&rhs_qubits[rhs_idx]) { + std::cmp::Ordering::Less => lhs_idx += 1, + std::cmp::Ordering::Greater => rhs_idx += 1, + std::cmp::Ordering::Equal => { + overlap.push(lhs_qubits[lhs_idx]); + lhs_idx += 1; + rhs_idx += 1; + } + } + } + overlap +} + +pub(crate) fn duplicate_qubits(qubits: impl IntoIterator) -> Vec { + let mut qubits: Vec = qubits.into_iter().collect(); + qubits.sort_unstable(); + + let mut duplicates = Vec::new(); + for window in qubits.windows(2) { + if window[0] == window[1] && duplicates.last() != Some(&window[0]) { + duplicates.push(window[0]); + } + } + duplicates +} + +pub(crate) fn assert_distinct_qubits(context: &str, qubits: impl IntoIterator) { + let duplicates = duplicate_qubits(qubits); + assert!( + duplicates.is_empty(), + "{context} requires distinct qubits; duplicated qubits: {duplicates:?}" + ); +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn overlapping_qubits_returns_sorted_deduplicated_intersection() { + assert_eq!(overlapping_qubits([3, 1, 1, 2], [2, 2, 3, 4]), vec![2, 3]); + } + + #[test] + fn duplicate_qubits_returns_sorted_deduplicated_repeats() { + assert_eq!(duplicate_qubits([5, 1, 5, 2, 2, 2]), vec![2, 5]); + } + + #[test] + #[should_panic(expected = "CX requires distinct qubits; duplicated qubits: [0, 2]")] + fn assert_distinct_qubits_reports_context_and_duplicates() { + assert_distinct_qubits("CX", [2, 0, 1, 2, 0]); + } +} diff --git a/crates/pecos-core/src/unitary_rep.rs b/crates/pecos-core/src/unitary_rep.rs index d86c3d6cf..04e4917e5 100644 --- a/crates/pecos-core/src/unitary_rep.rs +++ b/crates/pecos-core/src/unitary_rep.rs @@ -52,6 +52,7 @@ use crate::gate_type::GateType; use crate::pauli::PauliOperator; use crate::phase::Phase; +use crate::qubit_support::{assert_distinct_qubits, duplicate_qubits, overlapping_qubits}; use crate::{Angle64, Pauli, PauliString, QuarterPhase, QubitId}; use smallvec::SmallVec; use std::ops::{BitAnd, Mul, Neg}; @@ -487,11 +488,11 @@ impl Qubits { where F: Fn(usize) -> UnitaryRep, { - match self.0.len() { - 0 => UnitaryRep::Pauli(PauliString::default()), // Identity - 1 => gate_fn(self.0[0].0), - _ => UnitaryRep::Tensor(self.0.iter().map(|q| gate_fn(q.0)).collect()), - } + self.0 + .iter() + .map(|q| gate_fn(q.0)) + .reduce(|lhs, rhs| lhs & rhs) + .unwrap_or_else(|| UnitaryRep::Pauli(PauliString::default())) } } @@ -594,11 +595,11 @@ impl QubitPairs { where F: Fn(usize, usize) -> UnitaryRep, { - match self.0.len() { - 0 => UnitaryRep::Pauli(PauliString::default()), // Identity - 1 => gate_fn(self.0[0].0.0, self.0[0].1.0), - _ => UnitaryRep::Tensor(self.0.iter().map(|(q0, q1)| gate_fn(q0.0, q1.0)).collect()), - } + self.0 + .iter() + .map(|(q0, q1)| gate_fn(q0.0, q1.0)) + .reduce(|lhs, rhs| lhs & rhs) + .unwrap_or_else(|| UnitaryRep::Pauli(PauliString::default())) } } @@ -756,6 +757,22 @@ fn parse_qubits(tokens: &[&str]) -> Result, ParseUnitaryRepError> { .collect() } +fn require_distinct_parsed_qubits( + context: &str, + qubits: &[usize], +) -> Result<(), ParseUnitaryRepError> { + let duplicates = duplicate_qubits(qubits.iter().copied()); + if duplicates.is_empty() { + Ok(()) + } else { + Err(ParseUnitaryRepError { + message: format!( + "{context} requires distinct qubits; duplicated qubits: {duplicates:?}" + ), + }) + } +} + impl FromStr for UnitaryRep { type Err = ParseUnitaryRepError; @@ -840,6 +857,9 @@ impl FromStr for UnitaryRep { ), }); } + if expected > 1 { + require_distinct_parsed_qubits(rot_name, &qubits)?; + } return Ok(UnitaryRep::rotation( rot_type, angle, @@ -877,6 +897,9 @@ impl FromStr for UnitaryRep { ), }); } + if expected > 1 { + require_distinct_parsed_qubits(gate_name, &qubits)?; + } Ok(UnitaryRep::gate(gate_type, SmallVec::from_vec(qubits))) } @@ -942,6 +965,7 @@ impl FromStr for UnitaryRep { message: format!("{gate_name} requires 2 qubits, got {}", qubits.len()), }); } + require_distinct_parsed_qubits(gate_name, &qubits)?; Ok(UnitaryRep::gate(GateType::CX, SmallVec::from_vec(qubits))) } "CY" => { @@ -951,6 +975,7 @@ impl FromStr for UnitaryRep { message: format!("CY requires 2 qubits, got {}", qubits.len()), }); } + require_distinct_parsed_qubits("CY", &qubits)?; Ok(UnitaryRep::gate(GateType::CY, SmallVec::from_vec(qubits))) } "CZ" => { @@ -960,6 +985,7 @@ impl FromStr for UnitaryRep { message: format!("CZ requires 2 qubits, got {}", qubits.len()), }); } + require_distinct_parsed_qubits("CZ", &qubits)?; Ok(UnitaryRep::gate(GateType::CZ, SmallVec::from_vec(qubits))) } "SWAP" => { @@ -969,6 +995,7 @@ impl FromStr for UnitaryRep { message: format!("SWAP requires 2 qubits, got {}", qubits.len()), }); } + require_distinct_parsed_qubits("SWAP", &qubits)?; Ok(UnitaryRep::gate(GateType::SWAP, SmallVec::from_vec(qubits))) } @@ -980,6 +1007,7 @@ impl FromStr for UnitaryRep { message: format!("{gate_name} requires 3 qubits, got {}", qubits.len()), }); } + require_distinct_parsed_qubits(gate_name, &qubits)?; Ok(UnitaryRep::gate(GateType::CCX, SmallVec::from_vec(qubits))) } @@ -994,25 +1022,61 @@ impl FromStr for UnitaryRep { impl UnitaryRep { /// Creates a rotation gate expression. + /// + /// # Panics + /// + /// Panics if `qubits` does not match the rotation arity, or if a + /// multi-qubit rotation repeats a qubit. #[must_use] pub fn rotation( rotation_type: RotationType, angle: Angle64, qubits: impl Into>, ) -> Self { + let qubits = qubits.into(); + let expected = rotation_type.num_qubits(); + assert_eq!( + qubits.len(), + expected, + "{:?} requires {expected} qubit(s), got {}", + rotation_type.to_gate_type(), + qubits.len() + ); + if expected > 1 { + assert_distinct_qubits( + &format!("{:?}", rotation_type.to_gate_type()), + qubits.iter().copied(), + ); + } Self::Gate( Unitary::Rotation { rotation_type, angle, }, - qubits.into(), + qubits, ) } /// Creates a fixed gate expression. + /// + /// # Panics + /// + /// Panics if `qubits` does not match the gate arity, or if a + /// multi-qubit gate repeats a qubit. #[must_use] pub fn gate(gate_type: GateType, qubits: impl Into>) -> Self { - Self::Gate(Unitary::Named(gate_type), qubits.into()) + let qubits = qubits.into(); + let expected = gate_type.quantum_arity(); + assert_eq!( + qubits.len(), + expected, + "{gate_type:?} requires {expected} qubit(s), got {}", + qubits.len() + ); + if expected > 1 { + assert_distinct_qubits(&format!("{gate_type:?}"), qubits.iter().copied()); + } + Self::Gate(Unitary::Named(gate_type), qubits) } /// Returns the adjoint (Hermitian conjugate) of this expression. @@ -1402,10 +1466,10 @@ impl UnitaryRep { let mut result = PauliString::new(); for part in parts { let ps = part.try_to_pauli_string()?; - // Merge: combine the Pauli operators - // For disjoint qubits, this is just concatenation - // For overlapping qubits, we multiply the Paulis - result = result * ps; + if !overlapping_qubits(result.qubits(), ps.qubits()).is_empty() { + return None; + } + result = result & ps; } Some(result) } @@ -2947,11 +3011,10 @@ pub fn RZs(angle: Angle64, qubits: impl Into) -> UnitaryRep { #[must_use] #[allow(non_snake_case)] pub fn RXX(angle: Angle64, q0: impl Into, q1: impl Into) -> UnitaryRep { - UnitaryRep::rotation( - RotationType::RXX, - angle, - smallvec::smallvec![q0.into().0, q1.into().0], - ) + let q0 = q0.into(); + let q1 = q1.into(); + assert_distinct_qubits("RXX", [q0.0, q1.0]); + UnitaryRep::rotation(RotationType::RXX, angle, smallvec::smallvec![q0.0, q1.0]) } /// RXX rotations on multiple qubit pairs. @@ -2960,9 +3023,7 @@ pub fn RXX(angle: Angle64, q0: impl Into, q1: impl Into) -> Un #[must_use] #[allow(non_snake_case)] pub fn RXXs(angle: Angle64, pairs: impl Into) -> UnitaryRep { - pairs - .into() - .apply(|q0, q1| UnitaryRep::rotation(RotationType::RXX, angle, smallvec::smallvec![q0, q1])) + pairs.into().apply(|q0, q1| RXX(angle, q0, q1)) } /// Two-qubit YY rotation by the given angle. @@ -2971,11 +3032,10 @@ pub fn RXXs(angle: Angle64, pairs: impl Into) -> UnitaryRep { #[must_use] #[allow(non_snake_case)] pub fn RYY(angle: Angle64, q0: impl Into, q1: impl Into) -> UnitaryRep { - UnitaryRep::rotation( - RotationType::RYY, - angle, - smallvec::smallvec![q0.into().0, q1.into().0], - ) + let q0 = q0.into(); + let q1 = q1.into(); + assert_distinct_qubits("RYY", [q0.0, q1.0]); + UnitaryRep::rotation(RotationType::RYY, angle, smallvec::smallvec![q0.0, q1.0]) } /// RYY rotations on multiple qubit pairs. @@ -2984,9 +3044,7 @@ pub fn RYY(angle: Angle64, q0: impl Into, q1: impl Into) -> Un #[must_use] #[allow(non_snake_case)] pub fn RYYs(angle: Angle64, pairs: impl Into) -> UnitaryRep { - pairs - .into() - .apply(|q0, q1| UnitaryRep::rotation(RotationType::RYY, angle, smallvec::smallvec![q0, q1])) + pairs.into().apply(|q0, q1| RYY(angle, q0, q1)) } /// Two-qubit ZZ rotation by the given angle. @@ -2995,11 +3053,10 @@ pub fn RYYs(angle: Angle64, pairs: impl Into) -> UnitaryRep { #[must_use] #[allow(non_snake_case)] pub fn RZZ(angle: Angle64, q0: impl Into, q1: impl Into) -> UnitaryRep { - UnitaryRep::rotation( - RotationType::RZZ, - angle, - smallvec::smallvec![q0.into().0, q1.into().0], - ) + let q0 = q0.into(); + let q1 = q1.into(); + assert_distinct_qubits("RZZ", [q0.0, q1.0]); + UnitaryRep::rotation(RotationType::RZZ, angle, smallvec::smallvec![q0.0, q1.0]) } /// RZZ rotations on multiple qubit pairs. @@ -3008,9 +3065,7 @@ pub fn RZZ(angle: Angle64, q0: impl Into, q1: impl Into) -> Un #[must_use] #[allow(non_snake_case)] pub fn RZZs(angle: Angle64, pairs: impl Into) -> UnitaryRep { - pairs - .into() - .apply(|q0, q1| UnitaryRep::rotation(RotationType::RZZ, angle, smallvec::smallvec![q0, q1])) + pairs.into().apply(|q0, q1| RZZ(angle, q0, q1)) } // --- Gate constructors - Named single-qubit Cliffords --- @@ -3194,10 +3249,10 @@ pub fn Hs(qubits: impl Into) -> UnitaryRep { #[must_use] #[allow(non_snake_case)] pub fn CX(control: impl Into, target: impl Into) -> UnitaryRep { - UnitaryRep::gate( - GateType::CX, - smallvec::smallvec![control.into().0, target.into().0], - ) + let control = control.into(); + let target = target.into(); + assert_distinct_qubits("CX", [control.0, target.0]); + UnitaryRep::gate(GateType::CX, smallvec::smallvec![control.0, target.0]) } /// CX gates on multiple qubit pairs. @@ -3206,9 +3261,7 @@ pub fn CX(control: impl Into, target: impl Into) -> UnitaryRep #[must_use] #[allow(non_snake_case)] pub fn CXs(pairs: impl Into) -> UnitaryRep { - pairs - .into() - .apply(|ctrl, tgt| UnitaryRep::gate(GateType::CX, smallvec::smallvec![ctrl, tgt])) + pairs.into().apply(CX) } /// Controlled-Y gate. @@ -3217,10 +3270,10 @@ pub fn CXs(pairs: impl Into) -> UnitaryRep { #[must_use] #[allow(non_snake_case)] pub fn CY(control: impl Into, target: impl Into) -> UnitaryRep { - UnitaryRep::gate( - GateType::CY, - smallvec::smallvec![control.into().0, target.into().0], - ) + let control = control.into(); + let target = target.into(); + assert_distinct_qubits("CY", [control.0, target.0]); + UnitaryRep::gate(GateType::CY, smallvec::smallvec![control.0, target.0]) } /// CY gates on multiple qubit pairs. @@ -3229,9 +3282,7 @@ pub fn CY(control: impl Into, target: impl Into) -> UnitaryRep #[must_use] #[allow(non_snake_case)] pub fn CYs(pairs: impl Into) -> UnitaryRep { - pairs - .into() - .apply(|ctrl, tgt| UnitaryRep::gate(GateType::CY, smallvec::smallvec![ctrl, tgt])) + pairs.into().apply(CY) } /// Controlled-Z gate. @@ -3240,7 +3291,10 @@ pub fn CYs(pairs: impl Into) -> UnitaryRep { #[must_use] #[allow(non_snake_case)] pub fn CZ(q0: impl Into, q1: impl Into) -> UnitaryRep { - UnitaryRep::gate(GateType::CZ, smallvec::smallvec![q0.into().0, q1.into().0]) + let q0 = q0.into(); + let q1 = q1.into(); + assert_distinct_qubits("CZ", [q0.0, q1.0]); + UnitaryRep::gate(GateType::CZ, smallvec::smallvec![q0.0, q1.0]) } /// CZ gates on multiple qubit pairs. @@ -3249,9 +3303,7 @@ pub fn CZ(q0: impl Into, q1: impl Into) -> UnitaryRep { #[must_use] #[allow(non_snake_case)] pub fn CZs(pairs: impl Into) -> UnitaryRep { - pairs - .into() - .apply(|q0, q1| UnitaryRep::gate(GateType::CZ, smallvec::smallvec![q0, q1])) + pairs.into().apply(CZ) } /// SWAP gate. @@ -3260,10 +3312,10 @@ pub fn CZs(pairs: impl Into) -> UnitaryRep { #[must_use] #[allow(non_snake_case)] pub fn SWAP(q0: impl Into, q1: impl Into) -> UnitaryRep { - UnitaryRep::gate( - GateType::SWAP, - smallvec::smallvec![q0.into().0, q1.into().0], - ) + let q0 = q0.into(); + let q1 = q1.into(); + assert_distinct_qubits("SWAP", [q0.0, q1.0]); + UnitaryRep::gate(GateType::SWAP, smallvec::smallvec![q0.0, q1.0]) } /// SWAP gates on multiple qubit pairs. @@ -3272,9 +3324,7 @@ pub fn SWAP(q0: impl Into, q1: impl Into) -> UnitaryRep { #[must_use] #[allow(non_snake_case)] pub fn SWAPs(pairs: impl Into) -> UnitaryRep { - pairs - .into() - .apply(|q0, q1| UnitaryRep::gate(GateType::SWAP, smallvec::smallvec![q0, q1])) + pairs.into().apply(SWAP) } /// SZZ gate: RZZ(π/2) @@ -3283,10 +3333,13 @@ pub fn SWAPs(pairs: impl Into) -> UnitaryRep { #[must_use] #[allow(non_snake_case)] pub fn SZZ(q0: impl Into, q1: impl Into) -> UnitaryRep { + let q0 = q0.into(); + let q1 = q1.into(); + assert_distinct_qubits("SZZ", [q0.0, q1.0]); UnitaryRep::rotation( RotationType::RZZ, Angle64::QUARTER_TURN, - smallvec::smallvec![q0.into().0, q1.into().0], + smallvec::smallvec![q0.0, q1.0], ) } @@ -3296,13 +3349,7 @@ pub fn SZZ(q0: impl Into, q1: impl Into) -> UnitaryRep { #[must_use] #[allow(non_snake_case)] pub fn SZZs(pairs: impl Into) -> UnitaryRep { - pairs.into().apply(|q0, q1| { - UnitaryRep::rotation( - RotationType::RZZ, - Angle64::QUARTER_TURN, - smallvec::smallvec![q0, q1], - ) - }) + pairs.into().apply(SZZ) } // --- Gate constructors - Three-qubit gates --- @@ -3315,19 +3362,25 @@ pub fn CCX( c1: impl Into, target: impl Into, ) -> UnitaryRep { - UnitaryRep::gate( - GateType::CCX, - smallvec::smallvec![c0.into().0, c1.into().0, target.into().0], - ) + let c0 = c0.into(); + let c1 = c1.into(); + let target = target.into(); + assert_distinct_qubits("CCX", [c0.0, c1.0, target.0]); + UnitaryRep::gate(GateType::CCX, smallvec::smallvec![c0.0, c1.0, target.0]) } // --- UnitaryRep implementations --- -// Tensor product: & impl BitAnd for UnitaryRep { type Output = UnitaryRep; fn bitand(self, rhs: UnitaryRep) -> UnitaryRep { + let overlap = overlapping_qubits(self.qubits(), rhs.qubits()); + assert!( + overlap.is_empty(), + "tensor product requires disjoint unitary support; overlapping qubits: {overlap:?}" + ); + match (self, rhs) { // Pauli & Pauli: use PauliString tensor product (UnitaryRep::Pauli(a), UnitaryRep::Pauli(b)) => UnitaryRep::Pauli(a & b), @@ -3657,6 +3710,12 @@ mod tests { assert!(matches!(mixed, UnitaryRep::Tensor(_))); } + #[test] + #[should_panic(expected = "tensor product requires disjoint unitary support")] + fn test_tensor_product_rejects_overlapping_qubits() { + let _ = X(0) & H(0); + } + #[test] fn test_composition() { let circuit = T(0) * H(0); @@ -3675,6 +3734,22 @@ mod tests { assert!(cz.is_clifford()); } + #[test] + #[should_panic(expected = "CX requires 2 qubit(s), got 1")] + fn test_low_level_gate_constructor_rejects_wrong_arity() { + let _ = UnitaryRep::gate(GateType::CX, smallvec::smallvec![0]); + } + + #[test] + #[should_panic(expected = "RXX requires 2 qubit(s), got 1")] + fn test_low_level_rotation_constructor_rejects_wrong_arity() { + let _ = UnitaryRep::rotation( + RotationType::RXX, + Angle64::QUARTER_TURN, + smallvec::smallvec![0], + ); + } + #[test] fn test_adjoint() { let t = T(0); @@ -4237,6 +4312,13 @@ mod tests { } } + #[test] + fn test_try_to_pauli_string_rejects_overlapping_tensor_node() { + let invalid_tensor = UnitaryRep::Tensor(vec![X(0), Z(0)]); + + assert!(invalid_tensor.try_to_pauli_string().is_none()); + } + #[test] fn test_try_to_pauli_non_pauli() { // Quarter-turn rotations should not convert @@ -4373,6 +4455,100 @@ mod tests { let _ = Zs(1..=0); } + #[test] + #[should_panic(expected = "tensor product requires disjoint unitary support")] + fn test_plural_single_qubit_tensor_rejects_duplicate_qubits() { + let _ = Hs([0, 0]); + } + + #[test] + #[should_panic(expected = "tensor product requires disjoint unitary support")] + fn test_plural_two_qubit_tensor_rejects_overlapping_pairs() { + let _ = CXs([(0, 1), (1, 2)]); + } + + #[test] + #[should_panic(expected = "CX requires distinct qubits")] + fn test_two_qubit_gate_rejects_repeated_qubit() { + let _ = CX(0, 0); + } + + #[test] + #[should_panic(expected = "RZZ requires distinct qubits")] + fn test_two_qubit_rotation_rejects_repeated_qubit() { + let _ = RZZ(Angle64::QUARTER_TURN, 1, 1); + } + + #[test] + #[should_panic(expected = "CCX requires distinct qubits")] + fn test_three_qubit_gate_rejects_repeated_qubit() { + let _ = CCX(0, 1, 1); + } + + #[test] + #[should_panic(expected = "CX requires distinct qubits")] + fn test_low_level_gate_constructor_rejects_repeated_qubit() { + let _ = UnitaryRep::gate(GateType::CX, smallvec::smallvec![0, 0]); + } + + #[test] + #[should_panic(expected = "RXX requires distinct qubits")] + fn test_low_level_rotation_constructor_rejects_repeated_qubit() { + let _ = UnitaryRep::rotation( + RotationType::RXX, + Angle64::QUARTER_TURN, + smallvec::smallvec![2, 2], + ); + } + + #[test] + fn test_plural_helpers_match_chained_tensor_forms() { + assert_eq!(Xs([0, 2, 5]), X(0) & X(2) & X(5)); + assert_eq!(Ys([0, 2, 5]), Y(0) & Y(2) & Y(5)); + assert_eq!(Zs([0, 2, 5]), Z(0) & Z(2) & Z(5)); + assert_eq!(Ts([0, 1, 2]), T(0) & T(1) & T(2)); + assert_eq!(CXs([(0, 1), (2, 3)]), CX(0, 1) & CX(2, 3)); + assert_eq!(CZs([(0, 1), (2, 3)]), CZ(0, 1) & CZ(2, 3)); + assert_eq!(SWAPs([(0, 1), (2, 3)]), SWAP(0, 1) & SWAP(2, 3)); + assert_eq!(SZZs([(0, 1), (2, 3)]), SZZ(0, 1) & SZZ(2, 3)); + assert_eq!( + RZZs(Angle64::QUARTER_TURN, [(0, 1), (2, 3)]), + RZZ(Angle64::QUARTER_TURN, 0, 1) & RZZ(Angle64::QUARTER_TURN, 2, 3) + ); + } + + #[test] + fn test_plural_helpers_reject_duplicate_and_overlapping_supports() { + fn assert_tensor_overlap_panic(f: impl FnOnce() + std::panic::UnwindSafe) { + let err = std::panic::catch_unwind(f).expect_err("expected tensor overlap panic"); + let message = err + .downcast_ref::() + .map(String::as_str) + .or_else(|| err.downcast_ref::<&str>().copied()) + .unwrap_or(""); + assert!( + message.contains("tensor product requires disjoint"), + "unexpected panic message: {message}" + ); + } + + assert_tensor_overlap_panic(|| { + let _ = Xs([0, 0]); + }); + assert_tensor_overlap_panic(|| { + let _ = Ts([1, 1]); + }); + assert_tensor_overlap_panic(|| { + let _ = SWAPs([(0, 1), (1, 2)]); + }); + assert_tensor_overlap_panic(|| { + let _ = SZZs([(0, 2), (2, 3)]); + }); + assert_tensor_overlap_panic(|| { + let _ = RZZs(Angle64::QUARTER_TURN, [(0, 2), (2, 3)]); + }); + } + #[test] fn test_single_element_range() { // Xs(0..1) should be equivalent to X(0) @@ -5190,6 +5366,27 @@ mod tests { assert!("CCX 0 1".parse::().is_err()); } + #[test] + fn from_str_rejects_repeated_multi_qubit_gate_args() { + for (text, expected) in [ + ("CX 0 0", "CX requires distinct qubits"), + ("CY 0 0", "CY requires distinct qubits"), + ("CH 0 0", "CH requires distinct qubits"), + ("SWAP 2 2", "SWAP requires distinct qubits"), + ("RXX(pi/2) 1 1", "RXX requires distinct qubits"), + ("RYY(pi/2) 1 1", "RYY requires distinct qubits"), + ("RZZ(pi/2) 1 1", "RZZ requires distinct qubits"), + ("CCX 0 1 0", "CCX requires distinct qubits"), + ("TOFFOLI 0 0 1", "TOFFOLI requires distinct qubits"), + ] { + let err = text.parse::().unwrap_err(); + assert!( + err.message.contains(expected), + "{text} produced unexpected error: {err}" + ); + } + } + #[test] fn from_str_case_insensitive() { assert!("h 0".parse::().is_ok()); diff --git a/crates/pecos-engines/src/byte_message/builder.rs b/crates/pecos-engines/src/byte_message/builder.rs index 49ba0c43f..309f275d8 100644 --- a/crates/pecos-engines/src/byte_message/builder.rs +++ b/crates/pecos-engines/src/byte_message/builder.rs @@ -330,6 +330,8 @@ impl ByteMessageBuilder { /// This function will panic if the number of qubits in the gate exceeds 255, /// as the protocol uses a u8 to represent the qubit count. pub fn add_gate_command(&mut self, gate: &Gate) -> &mut Self { + gate.validate() + .unwrap_or_else(|err| panic!("Invalid gate command: {err}")); assert!( !gate.is_channel(), "Channel gates carry typed payloads and cannot be encoded in ByteMessage gate commands" @@ -989,6 +991,16 @@ mod tests { builder.add_gate_command(&gate); } + #[test] + #[should_panic(expected = "Invalid gate command")] + fn test_add_gate_command_rejects_invalid_gate_payload() { + let mut builder = ByteMessageBuilder::new(); + let _ = builder.for_quantum_operations(); + + let gate = Gate::cx(&[(0, 0)]); + builder.add_gate_command(&gate); + } + #[test] fn test_builder_basic() { // Create a builder diff --git a/crates/pecos-engines/src/byte_message/message.rs b/crates/pecos-engines/src/byte_message/message.rs index d8f2a308a..82b82c566 100644 --- a/crates/pecos-engines/src/byte_message/message.rs +++ b/crates/pecos-engines/src/byte_message/message.rs @@ -765,7 +765,13 @@ impl ByteMessage { ); } - Ok(Gate::new(gate_type, angles, params, qubits)) + let gate = Gate::new(gate_type, angles, params, qubits); + gate.validate().map_err(|err| { + PecosError::Input(format!( + "Invalid gate command payload for {gate_type:?}: {err}" + )) + })?; + Ok(gate) } // The parse_simple_measurement method has been removed as part of simplifying the protocol. @@ -827,6 +833,39 @@ mod tests { ); } + #[test] + fn test_raw_invalid_gate_payload_is_rejected_after_parse() { + use crate::byte_message::protocol::{GateHeader, MessageFlags, MessageType}; + + let header = GateHeader { + gate_type: GateType::CX as u8, + num_qubits: 2, + has_params: 0, + reserved: 0, + }; + let mut payload = Vec::new(); + payload.extend_from_slice(bytemuck::bytes_of(&header)); + payload.extend_from_slice(&0u32.to_le_bytes()); + payload.extend_from_slice(&0u32.to_le_bytes()); + + let mut builder = ByteMessage::quantum_operations_builder(); + builder.add_message(MessageType::Gate, &payload, MessageFlags::NONE); + let message = builder.build(); + + let err = message + .quantum_ops() + .expect_err("raw CX payload cannot use the same qubit twice"); + + assert!( + err.to_string().contains("Invalid gate command payload"), + "unexpected error: {err}" + ); + assert!( + err.to_string().contains("requires distinct qubits"), + "unexpected error: {err}" + ); + } + #[test] fn test_message_type() { // Create an empty message diff --git a/crates/pecos-qec/src/fault_tolerance/circuit_runner.rs b/crates/pecos-qec/src/fault_tolerance/circuit_runner.rs index d4b5c2cd6..71e154b2f 100644 --- a/crates/pecos-qec/src/fault_tolerance/circuit_runner.rs +++ b/crates/pecos-qec/src/fault_tolerance/circuit_runner.rs @@ -1315,7 +1315,8 @@ mod tests { let mut circuit = TickCircuit::new(); circuit.tick().pz(&[0, 1, 2]); // All prepared circuit.tick().h(&[0]); - circuit.tick().cx(&[(0, 1), (0, 2)]); + circuit.tick().cx(&[(0, 1)]); + circuit.tick().cx(&[(0, 2)]); // No measurement - outputs go to next stage let checker = FaultChecker::new(&circuit); @@ -1527,9 +1528,13 @@ mod tests { circuit.tick().h(&[0, 1, 3]); // Entangle to create logical |0> - circuit.tick().cx(&[(0, 2), (1, 2)]); - circuit.tick().cx(&[(0, 4), (1, 5), (3, 5)]); - circuit.tick().cx(&[(0, 6), (1, 6), (3, 6)]); + circuit.tick().cx(&[(0, 2)]); + circuit.tick().cx(&[(1, 2)]); + circuit.tick().cx(&[(0, 4), (1, 5)]); + circuit.tick().cx(&[(3, 5)]); + circuit.tick().cx(&[(0, 6)]); + circuit.tick().cx(&[(1, 6)]); + circuit.tick().cx(&[(3, 6)]); circuit.tick().cx(&[(3, 4)]); circuit diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs index 5026fb7af..4265a0c47 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs @@ -1464,6 +1464,66 @@ mod tests { ); } + #[test] + fn test_tick_dag_tick_dem_keeps_detector_observable_and_tracked_operator_distinct() { + use pecos_core::pauli::Z; + use pecos_quantum::{DagCircuit, TickCircuit}; + + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[0, 1]); + circuit.tick().h(&[0]); + circuit.tick().mz(&[0, 1]); + circuit.set_meta( + "num_measurements", + pecos_quantum::Attribute::String(circuit.num_measurements().to_string()), + ); + circuit + .add_detector_metadata(&[-2], None, Some("D0"), Some(0)) + .unwrap(); + circuit + .add_observable_metadata(&[-1], Some(0), Some("L0")) + .unwrap(); + circuit.tracked_operator_labeled("tracked_z0", Z(0)); + + let round_tripped = TickCircuit::from(&DagCircuit::from(&circuit)); + let dem = DemBuilder::from_tick_circuit(&round_tripped, 0.03, 0.0, 0.02, 0.0); + + assert_eq!(dem.num_detectors(), 1); + assert_eq!(dem.num_observables(), 1); + assert_eq!(dem.num_dem_outputs(), 1); + assert_eq!(dem.dem_outputs()[0].id, 0); + assert_eq!(dem.num_tracked_ops(), 1); + assert_eq!(dem.tracked_ops()[0].id, 0); + assert_eq!(dem.tracked_ops()[0].label.as_deref(), Some("tracked_z0")); + assert_eq!( + dem.tracked_ops()[0].pauli.as_ref().unwrap().to_sparse_str(), + "+Z0" + ); + + let standard_text = dem.to_string(); + assert!(standard_text.contains("logical_observable L0")); + assert!(!standard_text.contains("logical_observable L1")); + assert!(!standard_text.contains("pecos_tracked_op")); + + let pecos_text = dem.to_pecos_string(); + assert!(pecos_text.contains("pecos_observable")); + assert!(pecos_text.contains("pecos_tracked_op")); + + let summaries = dem.contribution_effect_summaries(); + assert!( + summaries + .iter() + .any(|summary| summary.effect.detectors.as_slice() == [0]), + "detector effects should survive Tick -> DAG -> Tick" + ); + assert!( + summaries + .iter() + .any(|summary| summary.effect.dem_outputs.as_slice() == [0]), + "observable effects should remain in L0" + ); + } + #[test] fn test_circuit_observable_annotation_is_not_double_counted() { use pecos_quantum::DagCircuit; diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index 972016aa6..7304ba6de 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -3216,6 +3216,25 @@ mod tests { ); } + #[test] + fn test_selected_observable_statistics_ignore_unselected_tracked_outputs() { + // L0 is the measured observable column; L1 represents a tracked + // operator column. The mechanism flips only L1, so observable-only + // logical statistics for L0 must stay zero while per-output counts + // still report the tracked-column flips. + let mechanisms = vec![(1.0, vec![], vec![1u32])]; + let sampler = SamplingEngine::from_mechanisms(mechanisms, 0, 2); + + let stats = sampler.sample_statistics_for_observable_indices(32, 42, &[0]); + + assert_eq!(stats.total_shots, 32); + assert_eq!(stats.per_dem_output, vec![0, 32]); + assert_eq!(stats.logical_error_count, 0); + assert_eq!(stats.undetectable_count, 0); + assert_eq!(stats.observable_counts(&[0]), vec![0]); + assert_eq!(stats.observable_counts(&[1]), vec![32]); + } + #[test] fn test_from_mechanisms_very_low_error_rate() { // Test geometric sampling efficiency with low error rate diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index 79a616ea4..d32722163 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -396,6 +396,11 @@ struct PropagatedEffectCache { } impl PropagatedEffectCache { + #[cfg(test)] + fn len(&self) -> usize { + self.singles.len() + } + fn single( &mut self, pauli: PauliType, @@ -2258,6 +2263,42 @@ mod tests { assert_eq!(combined, direct); } + #[test] + fn test_propagated_effect_cache_matches_fresh_propagation() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.tracked_operator_labeled("tracked_x0", PauliString::x(0)); + + let (gates, meas_pos) = flatten_tick_circuit(&tc); + let tracked_ops = parse_tracked_operator_annotations(&tc); + let fresh = propagate_single_effect(PauliType::Z, 0, 0, &gates, &meas_pos, &tracked_ops); + + let mut cache = PropagatedEffectCache::default(); + let first = cache.single(PauliType::Z, 0, 0, &gates, &meas_pos, &tracked_ops); + assert_eq!(first, fresh); + assert_eq!(cache.len(), 1); + + let mut mutated_clone = first.clone(); + mutated_clone.affected_measurements.clear(); + mutated_clone.affected_tracked_ops.clear(); + + let second = cache.single(PauliType::Z, 0, 0, &gates, &meas_pos, &tracked_ops); + assert_eq!(second, fresh); + assert_ne!(second, mutated_clone); + assert_eq!( + cache.len(), + 1, + "repeating the same propagation key should reuse the cached entry" + ); + + let other = cache.single(PauliType::X, 0, 0, &gates, &meas_pos, &tracked_ops); + let other_fresh = + propagate_single_effect(PauliType::X, 0, 0, &gates, &meas_pos, &tracked_ops); + assert_eq!(other, other_fresh); + assert_eq!(cache.len(), 2); + } + #[test] fn test_propagate_x_check_round_reaches_ancilla_only() { // X-check pattern: H(0) CX(0,1) CX(0,2) H(0) MZ(0) @@ -2892,6 +2933,208 @@ mod tests { ); } + #[test] + fn test_catalog_after_tick_dag_round_trip_keeps_outputs_and_tracked_ops_separate() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0), QubitId(1)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String(tc.num_measurements().to_string()), + ); + tc.add_detector_metadata(&[-1], None, Some("D0"), Some(0)) + .unwrap(); + tc.add_observable_metadata(&[-1], Some(0), Some("L0")) + .unwrap(); + tc.tracked_operator_labeled("tracked_z1", PauliString::z(1)); + + let round_tripped = TickCircuit::from(&pecos_quantum::DagCircuit::from(&tc)); + assert_eq!(round_tripped.annotations().len(), 1); + assert!(matches!( + round_tripped.annotations()[0].kind, + AnnotationKind::TrackedOperator + )); + + let catalog = build_fault_catalog( + &round_tripped, + &StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.01, + p_prep: 0.0, + }, + ) + .unwrap(); + + let h_loc = catalog + .locations + .iter() + .find(|loc| loc.gate_type == GateType::H && loc.qubits.as_slice() == [0]) + .unwrap(); + let x_fault = h_loc + .faults + .iter() + .find(|fault| fault.pauli.as_ref() == Some(&PauliString::x(0))) + .unwrap(); + assert_eq!(x_fault.affected_measurements, vec![0]); + assert_eq!(x_fault.affected_detectors, vec![0]); + assert_eq!(x_fault.affected_observables, vec![0]); + assert!(x_fault.affected_tracked_ops.is_empty()); + + let tracked_h_loc = catalog + .locations + .iter() + .find(|loc| loc.gate_type == GateType::H && loc.qubits.as_slice() == [1]) + .unwrap(); + let tracked_x_fault = tracked_h_loc + .faults + .iter() + .find(|fault| fault.pauli.as_ref() == Some(&PauliString::x(1))) + .unwrap(); + assert!(tracked_x_fault.affected_measurements.is_empty()); + assert!(tracked_x_fault.affected_detectors.is_empty()); + assert!(tracked_x_fault.affected_observables.is_empty()); + assert_eq!(tracked_x_fault.affected_tracked_ops, vec![0]); + + let meas_fault = catalog + .locations + .iter() + .find(|loc| loc.channel == FaultChannel::PMeas) + .and_then(|loc| loc.faults.first()) + .unwrap(); + assert_eq!(meas_fault.affected_measurements, vec![0]); + assert_eq!(meas_fault.affected_detectors, vec![0]); + assert_eq!(meas_fault.affected_observables, vec![0]); + assert!(meas_fault.affected_tracked_ops.is_empty()); + + assert!(catalog.to_mechanisms().iter().any(|mechanism| { + mechanism + .alternatives + .iter() + .any(|alternative| alternative.as_slice() == [0]) + })); + } + + #[test] + fn test_catalog_two_qubit_propagation_keeps_output_kinds_distinct() { + fn assert_case(gate_type: GateType, tracked_op: PauliString) { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + match gate_type { + GateType::CX => { + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(0)]); + } + GateType::CZ => { + tc.tick().cz(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(0)]); + } + GateType::SWAP => { + tc.tick().swap(&[(QubitId(0), QubitId(1))]); + tc.tick().cx(&[(QubitId(1), QubitId(2))]); + tc.tick().mz(&[QubitId(2)]); + } + other => panic!("unexpected gate type {other:?}"), + } + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String(tc.num_measurements().to_string()), + ); + tc.add_detector_metadata(&[-1], None, Some("D0"), Some(0)) + .unwrap(); + tc.add_observable_metadata(&[-1], Some(0), Some("L0")) + .unwrap(); + tc.tracked_operator_labeled("tracked", tracked_op); + + let catalog = build_fault_catalog( + &tc, + &StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + + let h_loc = catalog + .locations + .iter() + .find(|loc| loc.gate_type == GateType::H && loc.qubits.as_slice() == [0]) + .unwrap(); + let x_fault = h_loc + .faults + .iter() + .find(|fault| fault.pauli.as_ref() == Some(&PauliString::x(0))) + .unwrap(); + + assert_eq!(x_fault.affected_measurements, vec![0], "{gate_type:?}"); + assert_eq!(x_fault.affected_detectors, vec![0], "{gate_type:?}"); + assert_eq!(x_fault.affected_observables, vec![0], "{gate_type:?}"); + assert_eq!(x_fault.affected_tracked_ops, vec![0], "{gate_type:?}"); + } + + // X0 before CX becomes X0 X1. + assert_case(GateType::CX, PauliString::z(1)); + // X0 before CZ becomes X0 Z1. + assert_case(GateType::CZ, PauliString::x(1)); + // X0 before SWAP becomes X1, then the extra CX maps it to X1 X2. + assert_case(GateType::SWAP, PauliString::z(1)); + } + + #[test] + fn test_tracked_operator_phase_is_ignored_for_flip_tracking() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tracked_operator_labeled("plus_z0", PauliString::z(0)); + tc.tracked_operator_labeled( + "minus_z0", + PauliString::with_phase_and_paulis( + pecos_core::QuarterPhase::MinusOne, + vec![(Pauli::Z, QubitId(0))], + ), + ); + + let tracked_ops = parse_tracked_operator_annotations(&tc); + assert_eq!(tracked_ops.len(), 2); + assert!( + tracked_ops + .iter() + .all(|op| op.phase() == pecos_core::QuarterPhase::PlusOne) + ); + assert_eq!(tracked_ops[0], tracked_ops[1]); + + let catalog = build_fault_catalog( + &tc, + &StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + + let h_loc = catalog + .locations + .iter() + .find(|loc| loc.gate_type == GateType::H) + .unwrap(); + let x_fault = h_loc + .faults + .iter() + .find(|fault| fault.pauli.as_ref() == Some(&PauliString::x(0))) + .unwrap(); + let z_fault = h_loc + .faults + .iter() + .find(|fault| fault.pauli.as_ref() == Some(&PauliString::z(0))) + .unwrap(); + + assert_eq!(x_fault.affected_tracked_ops, vec![0, 1]); + assert_eq!(z_fault.affected_tracked_ops, Vec::::new()); + } + #[test] fn test_structural_catalog_includes_zero_probability_locations() { let mut tc = TickCircuit::new(); diff --git a/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs b/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs index 5e61ec6e7..6fff939f4 100644 --- a/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs +++ b/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs @@ -2026,7 +2026,8 @@ mod tests { let mut circuit = TickCircuit::new(); circuit.tick().pz(&[0, 1, 2]); // Initialize all data qubits circuit.tick().h(&[0]); // Some operations - circuit.tick().cx(&[(0, 1), (0, 2)]); + circuit.tick().cx(&[(0, 1)]); + circuit.tick().cx(&[(0, 2)]); // Data qubits are OUTPUT (not measured) circuit } @@ -2431,7 +2432,8 @@ mod tests { let mut circuit = TickCircuit::new(); circuit.tick().pz(&[0, 1, 2]); // All qubits prepared circuit.tick().h(&[0]); - circuit.tick().cx(&[(0, 1), (0, 2)]); + circuit.tick().cx(&[(0, 1)]); + circuit.tick().cx(&[(0, 2)]); // No measurement - outputs go to next stage let checker = GadgetChecker::from_circuit(&circuit); diff --git a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs index 00e35c5aa..8c4b956ba 100644 --- a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs @@ -251,10 +251,10 @@ impl<'a> InfluenceBuilder<'a> { /// Run symbolic simulation to get measurement correlations. fn run_symbolic_simulation(&self) -> MeasurementInfo { + let topo_order = self.dag.topological_order(); + // Determine number of qubits from the circuit - let max_qubit = self - .dag - .topological_order() + let max_qubit = topo_order .iter() .filter_map(|&node| self.dag.gate(node)) .flat_map(|op| op.qubits.iter()) @@ -266,11 +266,12 @@ impl<'a> InfluenceBuilder<'a> { let mut sim = SymbolicSparseStab::new(num_qubits); // Track node -> measurement index mapping - let mut node_to_meas_idx: Vec> = vec![None; self.dag.gate_count() + 1]; + let node_count = topo_order.iter().copied().max().map_or(0, |node| node + 1); + let mut node_to_meas_idx: Vec> = vec![None; node_count]; let mut meas_idx = 0; // Execute circuit symbolically - for &node in &self.dag.topological_order() { + for &node in &topo_order { if let Some(op) = self.dag.gate(node) { let qubits: Vec = op.qubits.iter().map(pecos_core::QubitId::index).collect(); diff --git a/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs b/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs index f8a7aabfe..634fe6a1e 100644 --- a/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs +++ b/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs @@ -3601,7 +3601,8 @@ mod tests { let mut circuit = TickCircuit::new(); circuit.tick().pz(&[0, 1, 2]); // Prepare all qubits circuit.tick().h(&[0]); - circuit.tick().cx(&[(0, 1), (0, 2)]); + circuit.tick().cx(&[(0, 1)]); + circuit.tick().cx(&[(0, 2)]); let input_qubits = detect_input_qubits(&circuit); assert!( @@ -4098,7 +4099,8 @@ mod tests { let mut circuit = TickCircuit::new(); circuit.tick().pz(&[0, 1, 2]); // All qubits prepared circuit.tick().h(&[0]); - circuit.tick().cx(&[(0, 1), (0, 2)]); + circuit.tick().cx(&[(0, 1)]); + circuit.tick().cx(&[(0, 2)]); circuit.tick().mz(&[0, 1, 2]); // All measured let checker = PauliPropChecker::new(&circuit); @@ -4122,7 +4124,8 @@ mod tests { let mut circuit = TickCircuit::new(); circuit.tick().pz(&[0, 1, 2]); // All qubits prepared circuit.tick().h(&[0]); - circuit.tick().cx(&[(0, 1), (0, 2)]); + circuit.tick().cx(&[(0, 1)]); + circuit.tick().cx(&[(0, 2)]); // No measurement - outputs go to next stage let checker = PauliPropChecker::new(&circuit); @@ -4194,7 +4197,8 @@ mod tests { // Use a simple circuit where we know failures will occur let mut circuit = TickCircuit::new(); circuit.tick().pz(&[2]); // Ancilla - circuit.tick().cx(&[(0, 2), (1, 2)]); + circuit.tick().cx(&[(0, 2)]); + circuit.tick().cx(&[(1, 2)]); circuit.tick().mz(&[2]); let config = FaultCheckConfig::new().with_weight(1).all_paulis(); diff --git a/crates/pecos-quantum/src/channel.rs b/crates/pecos-quantum/src/channel.rs index dddd07f7f..430256286 100644 --- a/crates/pecos-quantum/src/channel.rs +++ b/crates/pecos-quantum/src/channel.rs @@ -614,20 +614,43 @@ impl PauliSum { }) } + /// Adds two Pauli sums after validating that they act on the same number + /// of qubits. + /// + /// # Errors + /// + /// Returns [`ChannelError::QubitCountMismatch`] when the two sums have + /// different qubit counts. + pub fn try_add(mut self, rhs: Self) -> Result { + if self.num_qubits != rhs.num_qubits { + return Err(ChannelError::QubitCountMismatch { + expected: self.num_qubits, + actual: rhs.num_qubits, + }); + } + for (pauli, coefficient) in rhs.terms { + self.add_term(pauli, coefficient)?; + } + Ok(self) + } + /// Returns the trace of the represented operator. /// /// The trace is `identity_coefficient * 2^num_qubits`. + /// + /// # Errors + /// + /// Returns [`ChannelError::DimensionOverflow`] when `2^num_qubits` cannot + /// fit in `usize`. #[allow(clippy::cast_precision_loss)] - #[must_use] - pub fn trace(&self) -> Complex64 { - let dim = 2usize - .checked_pow(self.num_qubits.try_into().unwrap_or(u32::MAX)) - .unwrap_or(usize::MAX); - self.terms + pub fn trace(&self) -> Result { + let dim = hilbert_dim(self.num_qubits)?; + Ok(self + .terms .get(&PauliBitmaskSmall::identity()) .copied() .unwrap_or_else(|| Complex64::new(0.0, 0.0)) - * dim as f64 + * dim as f64) } } @@ -650,16 +673,15 @@ impl fmt::Display for PauliSum { impl Add for PauliSum { type Output = Self; - fn add(mut self, rhs: Self) -> Self::Output { - assert_eq!( - self.num_qubits, rhs.num_qubits, - "cannot add PauliSum values with different qubit counts" - ); - for (pauli, coefficient) in rhs.terms { - self.add_term(pauli, coefficient) - .expect("validated RHS term must remain valid"); - } - self + /// Adds two Pauli sums. + /// + /// # Panics + /// + /// Panics when the sums have different qubit counts. Use + /// [`PauliSum::try_add`] to handle this case without panicking. + fn add(self, rhs: Self) -> Self::Output { + self.try_add(rhs) + .expect("cannot add PauliSum values with different qubit counts") } } @@ -698,24 +720,6 @@ impl Mul for f64 { } } -impl Mul for PauliString { - type Output = PauliSum; - - fn mul(self, rhs: PauliSum) -> Self::Output { - rhs.conjugated_by_pauli_string(&self) - .expect("PauliString touches outside PauliSum qubit range") - } -} - -impl Mul<&PauliSum> for &PauliString { - type Output = PauliSum; - - fn mul(self, rhs: &PauliSum) -> Self::Output { - rhs.conjugated_by_pauli_string(self) - .expect("PauliString touches outside PauliSum qubit range") - } -} - /// Sparse Pauli error channel represented by probabilities. #[derive(Clone, Debug, PartialEq)] pub struct PauliChannel { @@ -2051,11 +2055,9 @@ impl SuperOp { /// Returns an error when qubit counts differ. pub fn compose(&self, other: &Self) -> Result { if self.num_qubits != other.num_qubits { - return Err(ChannelError::InvalidMatrixShape { - expected_rows: self.matrix.nrows(), - expected_cols: self.matrix.ncols(), - rows: other.matrix.nrows(), - cols: other.matrix.ncols(), + return Err(ChannelError::QubitCountMismatch { + expected: self.num_qubits, + actual: other.num_qubits, }); } Self::try_new(self.num_qubits, &self.matrix * &other.matrix) @@ -3209,6 +3211,69 @@ mod tests { } } + fn apply_kraus_direct(kraus: &KrausOps, operator: &DMatrix) -> DMatrix { + let mut output = DMatrix::zeros(operator.nrows(), operator.ncols()); + for k in kraus.operators() { + output += k * operator * k.adjoint(); + } + output + } + + fn direct_superop_from_kraus(kraus: &KrausOps) -> DMatrix { + let dim = hilbert_dim(kraus.num_qubits()).unwrap(); + let dim_squared = dim * dim; + let mut matrix = DMatrix::zeros(dim_squared, dim_squared); + for input_col in 0..dim { + for input_row in 0..dim { + let mut input = DMatrix::zeros(dim, dim); + input[(input_row, input_col)] = Complex64::new(1.0, 0.0); + let output = apply_kraus_direct(kraus, &input); + let input_idx = matrix_unit_index(dim, input_row, input_col); + for output_col in 0..dim { + for output_row in 0..dim { + let output_idx = matrix_unit_index(dim, output_row, output_col); + matrix[(output_idx, input_idx)] = output[(output_row, output_col)]; + } + } + } + } + matrix + } + + fn direct_ptm_from_kraus(kraus: &KrausOps) -> DMatrix { + let num_qubits = kraus.num_qubits(); + let basis = pauli_basis_matrices(num_qubits).unwrap(); + let dim = hilbert_dim(num_qubits).unwrap(); + #[allow(clippy::cast_precision_loss)] + let dim_f = dim as f64; + let mut matrix = DMatrix::zeros(basis.len(), basis.len()); + for input_idx in 0..basis.len() { + let evolved = apply_kraus_direct(kraus, &basis[input_idx]); + for output_idx in 0..basis.len() { + let entry = trace_complex(&(&basis[output_idx] * &evolved)) / dim_f; + assert!( + entry.im.abs() < 1e-10, + "PTM oracle produced complex entry {entry}" + ); + matrix[(output_idx, input_idx)] = entry.re; + } + } + matrix + } + + fn direct_matrix_unit_outputs(kraus: &KrausOps) -> Vec> { + let dim = hilbert_dim(kraus.num_qubits()).unwrap(); + let mut outputs = Vec::with_capacity(dim * dim); + for input_col in 0..dim { + for input_row in 0..dim { + let mut input = DMatrix::zeros(dim, dim); + input[(input_row, input_col)] = Complex64::new(1.0, 0.0); + outputs.push(apply_kraus_direct(kraus, &input)); + } + } + outputs + } + fn assert_ptm_entry(ptm: &Ptm, output: &str, input: &str, expected: f64) { let output_idx = labels(ptm.num_qubits()) .iter() @@ -3261,6 +3326,42 @@ mod tests { } } + #[test] + fn zero_qubit_channel_representations_are_scalar_identity() { + let ptm = Ptm::identity(0).unwrap(); + assert_eq!(ptm.matrix().shape(), (1, 1)); + assert_close(ptm.entry(0, 0), 1.0); + + let mut probabilities = BTreeMap::new(); + probabilities.insert(PauliBitmaskSmall::identity(), 1.0); + let pauli_channel = PauliChannel::try_new(0, probabilities).unwrap(); + assert_close(pauli_channel.total_error_rate(), 0.0); + assert_matrix_close(pauli_channel.to_ptm().unwrap().matrix(), ptm.matrix()); + + let kraus = KrausOps::try_new( + 0, + vec![DMatrix::from_element(1, 1, Complex64::new(1.0, 0.0))], + ) + .unwrap(); + assert!(kraus.is_trace_preserving()); + + let choi = kraus.to_choi().unwrap(); + assert_eq!(choi.matrix().shape(), (1, 1)); + assert_complex_close(choi.matrix()[(0, 0)], Complex64::new(1.0, 0.0)); + assert!(choi.is_cptp()); + + let superop = kraus.to_superop().unwrap(); + assert_eq!(superop.num_qubits(), 0); + assert_complex_close(superop.matrix()[(0, 0)], Complex64::new(1.0, 0.0)); + + let chi = kraus.to_chi().unwrap(); + assert_complex_close(chi.matrix()[(0, 0)], Complex64::new(1.0, 0.0)); + + let stinespring = kraus.to_stinespring().unwrap(); + assert_eq!(stinespring.environment_dim(), 1); + assert_complex_close(stinespring.isometry()[(0, 0)], Complex64::new(1.0, 0.0)); + } + #[test] fn pauli_sum_add_scalar_simplify_and_trace() { let identity = PauliBitmaskSmall::identity(); @@ -3279,7 +3380,57 @@ mod tests { let c = (a + b) * 2.0; assert_eq!(c.terms().len(), 2); assert_complex_close(*c.terms().get(&identity).unwrap(), Complex64::new(4.0, 0.0)); - assert_complex_close(c.trace(), Complex64::new(8.0, 0.0)); + assert_complex_close(c.trace().unwrap(), Complex64::new(8.0, 0.0)); + } + + #[test] + fn pauli_sum_trace_reports_dimension_overflow() { + let sum = PauliSum::new(usize::MAX); + assert_eq!( + sum.trace().unwrap_err(), + ChannelError::DimensionOverflow { + num_qubits: usize::MAX + } + ); + } + + #[test] + fn pauli_sum_try_add_reports_qubit_mismatch() { + let a = PauliSum::new(1); + let b = PauliSum::new(2); + + assert_eq!( + a.try_add(b).unwrap_err(), + ChannelError::QubitCountMismatch { + expected: 1, + actual: 2 + } + ); + } + + #[test] + fn pauli_sum_try_add_merges_terms_and_drops_cancellations() { + let identity = PauliBitmaskSmall::identity(); + let x0 = PauliBitmaskSmall::x(0); + let z0 = PauliBitmaskSmall::z(0); + + let mut a = PauliSum::new(1); + a.add_term(identity.clone(), Complex64::new(2.0, 0.0)) + .unwrap(); + a.add_term(x0.clone(), Complex64::new(1.0, 0.0)).unwrap(); + + let mut b = PauliSum::new(1); + b.add_term(x0.clone(), Complex64::new(-1.0, 0.0)).unwrap(); + b.add_term(z0.clone(), Complex64::new(0.5, 0.0)).unwrap(); + + let sum = a.try_add(b).unwrap(); + assert_eq!(sum.terms().len(), 2); + assert!(sum.terms().get(&x0).is_none()); + assert_complex_close( + *sum.terms().get(&identity).unwrap(), + Complex64::new(2.0, 0.0), + ); + assert_complex_close(*sum.terms().get(&z0).unwrap(), Complex64::new(0.5, 0.0)); } #[test] @@ -3302,7 +3453,7 @@ mod tests { sum.add_term(PauliBitmaskSmall::z(0), Complex64::new(3.0, 0.0)) .unwrap(); - let conjugated = PauliString::z(0) * sum; + let conjugated = sum.conjugated_by_pauli_string(&PauliString::z(0)).unwrap(); assert_complex_close( *conjugated.terms().get(&PauliBitmaskSmall::x(0)).unwrap(), Complex64::new(-2.0, 0.0), @@ -3692,6 +3843,34 @@ mod tests { assert!(compose_kraus.is_trace_preserving()); } + #[test] + fn kraus_tensor_rejects_manually_constructed_overlapping_subsystems() { + let tensor = ChannelExpr::Tensor(vec![ + pecos_core::channel::BitFlip(0.1, 0), + pecos_core::channel::Dephasing(0.2, 0), + ]); + + assert!(matches!( + KrausOps::from_channel_expr(&tensor), + Err(ChannelError::DuplicateSubsystem { qubit: 0 }) + )); + } + + #[test] + fn kraus_tensor_and_compose_reject_empty_manual_exprs() { + let tensor = ChannelExpr::Tensor(Vec::new()); + let compose = ChannelExpr::Compose(Vec::new()); + + assert!(matches!( + KrausOps::from_channel_expr(&tensor), + Err(ChannelError::UnsupportedChannelExpr { .. }) + )); + assert!(matches!( + KrausOps::from_channel_expr(&compose), + Err(ChannelError::UnsupportedChannelExpr { .. }) + )); + } + #[test] fn kraus_from_channel_expr_can_embed_in_larger_system() { let expr = pecos_core::channel::BitFlip(0.25, 2); @@ -3883,6 +4062,90 @@ mod tests { assert_matrix_close(ptm.matrix(), Ptm::identity(1).unwrap().matrix()); } + #[test] + fn superop_choi_round_trip_for_amplitude_damping() { + let Op::Channel(expr) = op::AmplitudeDamping(0.25, 0) else { + panic!("expected channel"); + }; + let kraus = KrausOps::from_channel_expr(&expr).unwrap(); + let choi = kraus.to_choi().unwrap(); + + let superop = SuperOp::from_choi(&choi).unwrap(); + let recovered = superop.to_choi().unwrap(); + + assert_complex_matrix_close(recovered.matrix(), choi.matrix()); + assert_matrix_close( + superop.to_ptm().unwrap().matrix(), + kraus.to_ptm().unwrap().matrix(), + ); + } + + #[test] + fn superop_ptm_round_trip_for_depolarizing() { + let Op::Channel(expr) = op::Depolarizing(0.3, 0) else { + panic!("expected channel"); + }; + let ptm = Ptm::from_channel_expr(&expr).unwrap(); + + let superop = SuperOp::from_ptm(&ptm).unwrap(); + let recovered = superop.to_ptm().unwrap(); + + assert_matrix_close(recovered.matrix(), ptm.matrix()); + } + + #[test] + fn random_channels_match_direct_kraus_oracles_for_small_systems() { + for (num_qubits, num_kraus, seed) in [(1, 1, 11), (1, 3, 12), (2, 2, 21), (2, 4, 22)] { + let mut rng = PecosRng::seed_from_u64(seed); + let kraus = random_quantum_channel(&mut rng, num_qubits, num_kraus).unwrap(); + assert!(kraus.is_trace_preserving()); + + let superop = kraus.to_superop().unwrap(); + assert_complex_matrix_close(superop.matrix(), &direct_superop_from_kraus(&kraus)); + + let ptm = kraus.to_ptm().unwrap(); + assert_matrix_close(ptm.matrix(), &direct_ptm_from_kraus(&kraus)); + + let choi = kraus.to_choi().unwrap(); + let outputs = direct_matrix_unit_outputs(&kraus); + let reconstructed = ChoiMatrix::from_matrix_unit_outputs(num_qubits, &outputs).unwrap(); + assert_complex_matrix_close(choi.matrix(), reconstructed.matrix()); + + for input in matrix_unit_basis(num_qubits).unwrap() { + assert_complex_matrix_close( + &choi.apply_to_operator(&input).unwrap(), + &apply_kraus_direct(&kraus, &input), + ); + } + + let stinespring_superop = kraus.to_stinespring().unwrap().to_superop().unwrap(); + assert_complex_matrix_close(stinespring_superop.matrix(), superop.matrix()); + } + } + + #[test] + fn three_qubit_random_channel_matches_direct_oracles() { + let mut rng = PecosRng::seed_from_u64(1234); + let kraus = random_quantum_channel(&mut rng, 3, 2).unwrap(); + assert!(kraus.is_trace_preserving()); + + let superop = kraus.to_superop().unwrap(); + assert_eq!(superop.matrix().shape(), (64, 64)); + assert_complex_matrix_close(superop.matrix(), &direct_superop_from_kraus(&kraus)); + + let ptm = kraus.to_ptm().unwrap(); + assert_eq!(ptm.matrix().shape(), (64, 64)); + assert_matrix_close(ptm.matrix(), &direct_ptm_from_kraus(&kraus)); + + let choi = kraus.to_choi().unwrap(); + assert_eq!(choi.matrix().shape(), (64, 64)); + assert!(choi.is_cptp()); + assert_complex_matrix_close( + &choi.partial_trace_output().unwrap(), + &DMatrix::identity(8, 8), + ); + } + #[test] fn superop_compose_and_tensor_follow_matrix_semantics() { let x = KrausOps::from_unitary(&unitary::X(0), 1) @@ -3899,6 +4162,28 @@ mod tests { let tensor = identity.tensor(&identity).unwrap(); assert_eq!(tensor.num_qubits(), 2); assert_complex_matrix_close(tensor.matrix(), &DMatrix::::identity(16, 16)); + + assert_eq!( + identity.compose(&tensor).unwrap_err(), + ChannelError::QubitCountMismatch { + expected: 1, + actual: 2 + } + ); + } + + #[test] + fn stinespring_try_new_rejects_non_isometric_matrix() { + let err = Stinespring::try_new( + 1, + DMatrix::from_diagonal_element(2, 2, Complex64::new(2.0, 0.0)), + ) + .unwrap_err(); + + assert!(matches!( + err, + ChannelError::DecompositionFailed { reason } if reason.contains("not an isometry") + )); } #[test] @@ -3923,6 +4208,41 @@ mod tests { assert_matrix_close(recovered.matrix(), expected.matrix()); } + #[test] + fn chi_matrix_amplitude_damping_has_off_diagonal_terms_and_matches_ptm() { + let Op::Channel(expr) = op::AmplitudeDamping(0.25, 0) else { + panic!("expected channel"); + }; + let kraus = KrausOps::from_channel_expr(&expr).unwrap(); + let chi = ChiMatrix::from_kraus(&kraus).unwrap(); + + let has_off_diagonal = (0..chi.matrix().nrows()).any(|row| { + (0..chi.matrix().ncols()) + .any(|col| row != col && chi.matrix()[(row, col)].norm() > 1e-10) + }); + assert!( + has_off_diagonal, + "amplitude damping should have off-diagonal chi entries" + ); + + let recovered = chi.to_ptm().unwrap(); + let expected = Ptm::from_channel_expr(&expr).unwrap(); + assert_matrix_close(recovered.matrix(), expected.matrix()); + } + + #[test] + fn chi_choi_round_trip_for_amplitude_damping() { + let Op::Channel(expr) = op::AmplitudeDamping(0.25, 0) else { + panic!("expected channel"); + }; + let kraus = KrausOps::from_channel_expr(&expr).unwrap(); + let chi = ChiMatrix::from_kraus(&kraus).unwrap(); + + let recovered = chi.to_choi().unwrap().to_chi().unwrap(); + + assert_complex_matrix_close(recovered.matrix(), chi.matrix()); + } + #[test] fn stinespring_round_trips_trace_preserving_kraus_channels() { let Op::Channel(expr) = op::AmplitudeDamping(0.25, 0) else { @@ -4043,6 +4363,26 @@ mod tests { assert!(!reconstructed.is_unital()); } + #[test] + fn process_tomography_design_reconstructs_two_qubit_tensor_channel() { + let tensor = ChannelExpr::Tensor(vec![ + pecos_core::channel::AmplitudeDamping(0.25, 0), + pecos_core::channel::PhaseDamping(0.4, 1), + ]); + let kraus = KrausOps::from_channel_expr(&tensor).unwrap(); + let expected = kraus.to_choi().unwrap(); + let design = ProcessTomographyDesign::matrix_unit(2).unwrap(); + + let outputs = direct_matrix_unit_outputs(&kraus); + let reconstructed = design.reconstruct_choi(&outputs).unwrap(); + assert_complex_matrix_close(reconstructed.matrix(), expected.matrix()); + + let simulated_outputs = design.simulate_outputs(&expected).unwrap(); + for (direct, simulated) in outputs.iter().zip(simulated_outputs.iter()) { + assert_complex_matrix_close(simulated, direct); + } + } + #[test] fn process_tomography_design_rejects_invalid_inputs() { let design = ProcessTomographyDesign::matrix_unit(1).unwrap(); @@ -4183,6 +4523,22 @@ mod tests { )); } + #[test] + fn random_density_matrix_three_qubit_rank_limited_is_stable() { + let mut rng = PecosRng::seed_from_u64(789); + let rho = random_density_matrix_with_rank(&mut rng, 3, 3).unwrap(); + assert_eq!(rho.shape(), (8, 8)); + assert_complex_close(trace_complex(&rho), Complex64::new(1.0, 0.0)); + assert_complex_matrix_close(&rho, &rho.adjoint()); + + let purity = trace_complex(&(&rho * &rho)); + assert!(purity.im.abs() < 1e-10); + assert!( + purity.re > 1.0 / 8.0 - 1e-10 && purity.re <= 1.0 + 1e-10, + "unexpected 3-qubit density-matrix purity: {purity}" + ); + } + #[test] fn random_quantum_channel_is_cptp_and_reproducible() { let mut rng = PecosRng::seed_from_u64(123); diff --git a/crates/pecos-quantum/src/dag_circuit.rs b/crates/pecos-quantum/src/dag_circuit.rs index 3a2ee6641..04a48ff2e 100644 --- a/crates/pecos-quantum/src/dag_circuit.rs +++ b/crates/pecos-quantum/src/dag_circuit.rs @@ -126,10 +126,14 @@ impl DagTraversalIndex { self.max_qubit + 1 } - /// Returns the number of gates. + /// Returns the number of gate nodes in the traversal index. + /// + /// A batched DAG node still contributes one node here. Use + /// [`DagCircuit::gate_count`] when you need the number of individual gates + /// represented by batched gate nodes. #[inline] #[must_use] - pub fn num_gates(&self) -> usize { + pub fn num_gate_nodes(&self) -> usize { self.topo_order.len() } @@ -473,7 +477,7 @@ impl DagCircuit { // ==================== Gate operations ==================== - /// Adds a gate to the circuit. + /// Adds a validated gate to the circuit. /// /// Returns the node index of the newly added gate. /// The gate is not connected to any other gates yet - use [`connect`](Self::connect) @@ -482,7 +486,27 @@ impl DagCircuit { /// # Arguments /// /// * `gate` - The gate to add + /// + /// # Panics + /// + /// Panics if [`Gate::validate`] rejects the gate payload. Use + /// [`try_add_gate`](Self::try_add_gate) for fallible insertion. pub fn add_gate(&mut self, gate: Gate) -> usize { + self.try_add_gate(gate) + .unwrap_or_else(|err| panic!("Invalid gate: {err}")) + } + + /// Try to add a validated gate to the circuit. + /// + /// # Errors + /// + /// Returns an error if [`Gate::validate`] rejects the gate payload. + pub fn try_add_gate(&mut self, gate: Gate) -> Result { + gate.validate()?; + Ok(self.add_gate_unchecked(gate)) + } + + fn add_gate_unchecked(&mut self, gate: Gate) -> usize { let node_idx = self.dag.add_node(); // Ensure gates vector is large enough if node_idx >= self.gates.len() { @@ -531,8 +555,20 @@ impl DagCircuit { } /// Returns the number of gates in the circuit. + /// + /// Batched gate nodes count by individual gate. For example, a node carrying + /// `Gate::cx(&[(0, 1), (2, 3)])` contributes two gates. #[must_use] pub fn gate_count(&self) -> usize { + self.gates.iter().flatten().map(Gate::num_gates).sum() + } + + /// Returns the number of gate nodes stored in the DAG. + /// + /// A batched node carrying `Gate::cx(&[(0, 1), (2, 3)])` contributes one + /// gate node and two gates. + #[must_use] + pub fn gate_node_count(&self) -> usize { self.dag.node_count() } @@ -759,7 +795,8 @@ impl DagCircuit { .iter() .flatten() .filter(|g| g.is_single_qubit()) - .count() + .map(Gate::num_gates) + .sum() } /// Returns the count of two-qubit gates. @@ -769,7 +806,8 @@ impl DagCircuit { .iter() .flatten() .filter(|g| g.is_two_qubit()) - .count() + .map(Gate::num_gates) + .sum() } /// Returns the count of gates of a specific type. @@ -779,7 +817,8 @@ impl DagCircuit { .iter() .flatten() .filter(|g| g.gate_type == gate_type) - .count() + .map(Gate::num_gates) + .sum() } // ==================== Topological operations ==================== @@ -2173,6 +2212,44 @@ mod tests { assert_eq!(circuit.two_qubit_gate_count(), 1); } + #[test] + fn test_batched_gate_nodes_count_gates() { + let mut circuit = DagCircuit::new(); + + circuit.add_gate(Gate::h(&[0, 1, 2, 3])); + circuit.add_gate(Gate::cx(&[(0, 1), (2, 3)])); + + assert_eq!(circuit.nodes().len(), 2); + assert_eq!(circuit.gate_node_count(), 2); + assert_eq!(circuit.gate_count(), 6); + assert_eq!(circuit.build_traversal_index().num_gate_nodes(), 2); + assert_eq!(circuit.single_qubit_gate_count(), 4); + assert_eq!(circuit.two_qubit_gate_count(), 2); + assert_eq!(circuit.gate_type_count(GateType::H), 4); + assert_eq!(circuit.gate_type_count(GateType::CX), 2); + } + + #[test] + fn test_separate_compatible_nodes_remain_separate_nodes() { + let mut circuit = DagCircuit::new(); + + circuit.add_gate(Gate::h(&[0])); + circuit.add_gate(Gate::h(&[1])); + circuit.add_gate(Gate::cx(&[(2, 3)])); + circuit.add_gate(Gate::cx(&[(4, 5)])); + + assert_eq!(circuit.gate_node_count(), 4); + assert_eq!(circuit.gate_count(), 4); + assert_eq!(circuit.build_traversal_index().num_gate_nodes(), 4); + assert_eq!(circuit.gate_type_count(GateType::H), 2); + assert_eq!(circuit.gate_type_count(GateType::CX), 2); + + let ticks = crate::TickCircuit::from(&circuit); + assert_eq!(ticks.gate_count(), 4); + assert_eq!(ticks.gate_batch_count(), 2); + assert_eq!(ticks.get_tick(0).unwrap().gate_batch_count(), 2); + } + #[test] fn test_two_qubit_gate_multiple_wires() { let mut circuit = DagCircuit::new(); @@ -2817,4 +2894,22 @@ mod tests { assert_eq!(gate_attrs.get("duration"), Some(&Attribute::Float(50.0))); assert_eq!(gate_attrs.get("fidelity"), Some(&Attribute::Float(0.999))); } + + #[test] + fn test_try_add_gate_rejects_invalid_gate_payload() { + let mut circuit = DagCircuit::new(); + let err = circuit + .try_add_gate(Gate::cx(&[(0, 0)])) + .expect_err("DAG should reject invalid gate payloads"); + + assert!(err.contains("requires distinct qubits")); + assert!(circuit.nodes().is_empty()); + } + + #[test] + #[should_panic(expected = "Invalid gate")] + fn test_add_gate_panics_on_invalid_gate_payload() { + let mut circuit = DagCircuit::new(); + circuit.add_gate(Gate::cx(&[(0, 0)])); + } } diff --git a/crates/pecos-quantum/src/diamond_norm.rs b/crates/pecos-quantum/src/diamond_norm.rs index 5f6ba6bef..fd36aabd8 100644 --- a/crates/pecos-quantum/src/diamond_norm.rs +++ b/crates/pecos-quantum/src/diamond_norm.rs @@ -448,6 +448,24 @@ mod tests { assert_close(pauli_channel_diamond_norm(&left, &right).unwrap(), 0.4); } + #[test] + fn pauli_channel_diamond_norm_handles_sparse_three_qubit_channels() { + let mut left_probs = BTreeMap::new(); + left_probs.insert(basis_bitmask(3, 0).unwrap(), 0.7); + left_probs.insert(basis_bitmask(3, 1).unwrap(), 0.1); + left_probs.insert(basis_bitmask(3, 17).unwrap(), 0.2); + let left = PauliChannel::try_new(3, left_probs).unwrap(); + + let mut right_probs = BTreeMap::new(); + right_probs.insert(basis_bitmask(3, 0).unwrap(), 0.6); + right_probs.insert(basis_bitmask(3, 17).unwrap(), 0.1); + right_probs.insert(basis_bitmask(3, 63).unwrap(), 0.3); + let right = PauliChannel::try_new(3, right_probs).unwrap(); + + assert_close(pauli_channel_diamond_norm(&left, &right).unwrap(), 0.6); + assert_close(pauli_channel_diamond_distance(&left, &right).unwrap(), 0.3); + } + #[test] fn pauli_channel_diamond_norm_rejects_qubit_count_mismatch() { let left = PauliChannel::one_qubit(0.1, 0.0, 0.0).unwrap(); diff --git a/crates/pecos-quantum/src/lib.rs b/crates/pecos-quantum/src/lib.rs index 0e8123d16..418becf8f 100644 --- a/crates/pecos-quantum/src/lib.rs +++ b/crates/pecos-quantum/src/lib.rs @@ -87,8 +87,8 @@ pub use dag_circuit::{ TraversalWorkBuffers, }; pub use tick_circuit::{ - CustomGateError, GateSignatureMismatchError, QubitConflictError, Tick, TickCircuit, TickHandle, - TickMeasRef, TickMeasureHandle, TickPrepHandle, + CustomGateError, GateSignatureMismatchError, QubitConflictError, Tick, TickCircuit, + TickGateError, TickHandle, TickMeasRef, TickMeasureHandle, TickPrepHandle, }; pub use tick_circuit_soa::{ CircuitIndexes, GateBatch, GateId, GateStorage, MetadataStorage, TickBatches, TickCircuitSoA, diff --git a/crates/pecos-quantum/src/measures.rs b/crates/pecos-quantum/src/measures.rs index 05d1602ab..0943a9ba7 100644 --- a/crates/pecos-quantum/src/measures.rs +++ b/crates/pecos-quantum/src/measures.rs @@ -63,11 +63,25 @@ pub enum MeasureError { /// Actual column count. cols: usize, }, + /// Two channel/process representations have incompatible qubit counts. + QubitCountMismatch { + /// Expected qubit count. + expected: usize, + /// Actual qubit count. + actual: usize, + }, /// A value is not finite. NonFiniteValue { /// Offending value. value: Complex64, }, + /// A finite complex value was expected to be real within tolerance. + NonRealValue { + /// Offending value. + value: Complex64, + /// Allowed imaginary-part tolerance. + tolerance: f64, + }, /// A state vector is not normalized. InvalidStateNorm { /// Observed squared norm. @@ -161,7 +175,14 @@ impl fmt::Display for MeasureError { f, "invalid matrix shape {rows}x{cols}; expected {expected_rows}x{expected_cols}" ), + Self::QubitCountMismatch { expected, actual } => { + write!(f, "qubit count mismatch: expected {expected}, got {actual}") + } Self::NonFiniteValue { value } => write!(f, "non-finite value: {value}"), + Self::NonRealValue { value, tolerance } => write!( + f, + "value must be real within tolerance {tolerance}, got {value}" + ), Self::InvalidStateNorm { norm_sqr, tolerance, @@ -336,7 +357,10 @@ pub fn state_fidelity_with_density_matrix( .map(|(left, right)| left.conj() * right) .sum(); if value.im.abs() > DEFAULT_TOLERANCE { - return Err(MeasureError::NonFiniteValue { value }); + return Err(MeasureError::NonRealValue { + value, + tolerance: DEFAULT_TOLERANCE, + }); } Ok(value.re) } @@ -350,7 +374,10 @@ pub fn purity(rho: &DMatrix) -> Result { validate_density_matrix(rho)?; let value = trace(&(rho * rho)); if value.im.abs() > DEFAULT_TOLERANCE { - return Err(MeasureError::NonFiniteValue { value }); + return Err(MeasureError::NonRealValue { + value, + tolerance: DEFAULT_TOLERANCE, + }); } Ok(value.re) } @@ -422,11 +449,9 @@ pub fn shannon_entropy(probabilities: &[f64], base: f64) -> Result Result { if left.num_qubits() != right.num_qubits() { - return Err(MeasureError::InvalidMatrixShape { - expected_rows: left.matrix().nrows(), - expected_cols: left.matrix().ncols(), - rows: right.matrix().nrows(), - cols: right.matrix().ncols(), + return Err(MeasureError::QubitCountMismatch { + expected: left.num_qubits(), + actual: right.num_qubits(), }); } #[allow(clippy::cast_precision_loss)] @@ -1110,6 +1135,17 @@ mod tests { psi * psi.adjoint() } + fn werner_state(p: f64) -> DMatrix { + let bell = ket(&[ + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(0.0, 0.0), + Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), + ]); + pure_density(&bell) * Complex64::new(p, 0.0) + + DMatrix::identity(4, 4) * Complex64::new((1.0 - p) / 4.0, 0.0) + } + #[test] fn pure_state_fidelity_matches_known_values() { let zero = ket(&[Complex64::new(1.0, 0.0), Complex64::new(0.0, 0.0)]); @@ -1196,21 +1232,20 @@ mod tests { #[test] fn concurrence_matches_werner_state_threshold_formula() { - fn werner_state(p: f64) -> DMatrix { - let bell = ket(&[ - Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), - Complex64::new(0.0, 0.0), - Complex64::new(0.0, 0.0), - Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0), - ]); - pure_density(&bell) * Complex64::new(p, 0.0) - + DMatrix::identity(4, 4) * Complex64::new((1.0 - p) / 4.0, 0.0) - } - assert_close(concurrence(&werner_state(0.5)).unwrap(), 0.25); assert_close(concurrence(&werner_state(0.3)).unwrap(), 0.0); } + #[test] + fn entanglement_of_formation_matches_intermediate_werner_state() { + let rho = werner_state(0.5); + assert_close(concurrence(&rho).unwrap(), 0.25); + assert_close( + entanglement_of_formation(&rho).unwrap(), + 0.117_618_873_770_917_81, + ); + } + #[test] fn negativity_matches_bell_and_product_states() { let bell = ket(&[ @@ -1257,6 +1292,20 @@ mod tests { assert_close(product_terms[0].0, 1.0); } + #[test] + fn schmidt_decomposition_supports_unequal_bipartition() { + let mut ghz = DVector::zeros(8); + ghz[0] = Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0); + ghz[7] = Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0); + + let terms = schmidt_decomposition(&ghz, &[2, 4], &[0]).unwrap(); + assert_eq!(terms.len(), 2); + assert_close(terms[0].0, 1.0 / 2.0_f64.sqrt()); + assert_close(terms[1].0, 1.0 / 2.0_f64.sqrt()); + assert_eq!(terms[0].1.len(), 2); + assert_eq!(terms[0].2.len(), 4); + } + #[test] fn mutual_information_accepts_non_qubit_subsystem_dims() { let mut rho = DMatrix::zeros(6, 6); @@ -1326,6 +1375,45 @@ mod tests { assert_close((reduced - expected).norm(), 0.0); } + #[test] + fn partial_trace_subsystems_can_trace_noncontiguous_factors() { + let mut state = DVector::zeros(12); + state[0] = Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0); + state[11] = Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0); + let rho = pure_density(&state); + + let reduced = partial_trace_subsystems(&rho, &[2, 3, 2], &[0, 2]).unwrap(); + let mut expected = DMatrix::zeros(3, 3); + expected[(0, 0)] = Complex64::new(0.5, 0.0); + expected[(2, 2)] = Complex64::new(0.5, 0.0); + + assert_close((reduced - expected).norm(), 0.0); + } + + #[test] + fn three_qubit_ghz_reductions_have_expected_information() { + let mut ghz = DVector::zeros(8); + ghz[0] = Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0); + ghz[7] = Complex64::new(1.0 / 2.0_f64.sqrt(), 0.0); + let rho = pure_density(&ghz); + + let two_qubit_reduction = partial_trace_qubits(&rho, 3, &[2]).unwrap(); + let mut expected_two_qubit = DMatrix::zeros(4, 4); + expected_two_qubit[(0, 0)] = Complex64::new(0.5, 0.0); + expected_two_qubit[(3, 3)] = Complex64::new(0.5, 0.0); + assert_close((&two_qubit_reduction - &expected_two_qubit).norm(), 0.0); + assert_close(entropy(&two_qubit_reduction).unwrap(), 1.0); + assert_close( + mutual_information(&two_qubit_reduction, (2, 2)).unwrap(), + 1.0, + ); + + let one_qubit_reduction = partial_trace_qubits(&rho, 3, &[1, 2]).unwrap(); + let expected_one_qubit = DMatrix::from_diagonal_element(2, 2, Complex64::new(0.5, 0.0)); + assert_close((&one_qubit_reduction - expected_one_qubit).norm(), 0.0); + assert_close(entropy(&one_qubit_reduction).unwrap(), 1.0); + } + #[test] fn partial_trace_rejects_repeated_or_out_of_range_subsystems() { let mixed = DMatrix::from_diagonal_element(4, 4, Complex64::new(0.25, 0.0)); @@ -1371,4 +1459,32 @@ mod tests { ); assert_close(gate_error(&depolarizing, &identity).unwrap(), 0.2); } + + #[test] + fn process_fidelity_reports_qubit_count_mismatch() { + let one_qubit = Ptm::identity(1).unwrap(); + let two_qubit = Ptm::identity(2).unwrap(); + + assert_eq!( + process_fidelity(&one_qubit, &two_qubit).unwrap_err(), + MeasureError::QubitCountMismatch { + expected: 1, + actual: 2 + } + ); + assert_eq!( + average_gate_fidelity(&one_qubit, &two_qubit).unwrap_err(), + MeasureError::QubitCountMismatch { + expected: 1, + actual: 2 + } + ); + assert_eq!( + gate_error(&one_qubit, &two_qubit).unwrap_err(), + MeasureError::QubitCountMismatch { + expected: 1, + actual: 2 + } + ); + } } diff --git a/crates/pecos-quantum/src/pass.rs b/crates/pecos-quantum/src/pass.rs index 5e9814b1d..c39f6f39f 100644 --- a/crates/pecos-quantum/src/pass.rs +++ b/crates/pecos-quantum/src/pass.rs @@ -23,7 +23,7 @@ use std::collections::{BTreeMap, HashMap, HashSet}; use pecos_core::gate_type::GateType; use pecos_core::{Angle64, Gate, GateQubits, QubitId}; -use crate::{Attribute, DagCircuit, TickCircuit}; +use crate::{Attribute, DagCircuit, Tick, TickCircuit}; /// A transformation pass that can be applied to circuits. /// @@ -442,6 +442,66 @@ fn peephole_conjugation(middle: &Gate, h_qubit: QubitId) -> Option<(GateType, Ga } } +fn split_batched_tick_commands(circuit: &mut TickCircuit) { + let old_ticks = std::mem::take(circuit.ticks_vec_mut()); + let mut new_ticks = Vec::with_capacity(old_ticks.len()); + + for old_tick in old_ticks { + let mut new_tick = Tick::new(); + for (key, value) in old_tick.tick_attrs() { + new_tick.set_attr(key, value.clone()); + } + + for (gate_idx, gate) in old_tick.gates().iter().enumerate() { + let attrs: BTreeMap = old_tick + .gate_attrs(gate_idx) + .map(|(key, value)| (key.clone(), value.clone())) + .collect(); + + if gate.num_gates() <= 1 { + let new_idx = new_tick + .try_add_gate_preserving_command(gate.clone()) + .unwrap_or_else(|err| panic!("{err}")); + if !attrs.is_empty() { + new_tick.set_gate_attrs(new_idx, attrs); + } + continue; + } + + let arity = gate.gate_type.quantum_arity(); + for (instance_idx, qubits) in gate.qubits.chunks(arity).enumerate() { + if qubits.len() != arity { + continue; + } + + let mut split_gate = gate.clone(); + split_gate.qubits = qubits.iter().copied().collect(); + if gate.meas_ids.is_empty() { + split_gate.meas_ids.clear(); + } else { + let meas_start = instance_idx * arity; + let meas_end = meas_start + arity; + split_gate.meas_ids = gate.meas_ids[meas_start..meas_end] + .iter() + .copied() + .collect(); + } + + let new_idx = new_tick + .try_add_gate_preserving_command(split_gate) + .unwrap_or_else(|err| panic!("{err}")); + if !attrs.is_empty() { + new_tick.set_gate_attrs(new_idx, attrs.clone()); + } + } + } + + new_ticks.push(new_tick); + } + + *circuit.ticks_vec_mut() = new_ticks; +} + impl CircuitPass for SimplifyRotations { fn apply_tick(&self, circuit: &mut TickCircuit) { for tick in circuit.ticks_mut() { @@ -790,6 +850,8 @@ pub struct PeepholeOptimize; impl CircuitPass for PeepholeOptimize { fn apply_tick(&self, circuit: &mut TickCircuit) { + split_batched_tick_commands(circuit); + // Build per-qubit timeline: Vec of (tick_idx, gate_idx) in order. let mut timelines: HashMap> = HashMap::new(); for (ti, tick) in circuit.ticks().iter().enumerate() { @@ -1440,9 +1502,13 @@ mod tests { tc.tick().rzz(Angle64::HALF_TURN, &[(0, 1)]); SimplifyRotations.apply_tick(&mut tc); let gates = tc.ticks()[0].gates(); - assert_eq!(gates.len(), 2); + assert_eq!(gates.len(), 1); assert_eq!(gates[0].gate_type, GateType::Z); - assert_eq!(gates[1].gate_type, GateType::Z); + assert_eq!( + gates[0].qubits.as_slice(), + &[QubitId::from(0), QubitId::from(1)] + ); + assert_eq!(gates[0].num_gates(), 2); } #[test] @@ -1451,9 +1517,13 @@ mod tests { tc.tick().rxx(Angle64::HALF_TURN, &[(0, 1)]); SimplifyRotations.apply_tick(&mut tc); let gates = tc.ticks()[0].gates(); - assert_eq!(gates.len(), 2); + assert_eq!(gates.len(), 1); assert_eq!(gates[0].gate_type, GateType::X); - assert_eq!(gates[1].gate_type, GateType::X); + assert_eq!( + gates[0].qubits.as_slice(), + &[QubitId::from(0), QubitId::from(1)] + ); + assert_eq!(gates[0].num_gates(), 2); } #[test] @@ -1722,7 +1792,19 @@ mod tests { /// Convert a single `Gate` to an `UnitaryRep`. fn gate_to_unitary(gate: &pecos_core::Gate) -> Option { - let q0 = gate.qubits.first().copied()?; + let arity = gate.gate_type.quantum_arity(); + let mut ops = Vec::new(); + for qubits in gate.qubits.chunks(arity) { + if qubits.len() != arity { + return None; + } + ops.push(gate_instance_to_unitary(gate, qubits)?); + } + ops.into_iter().reduce(|a, b| a & b) + } + + fn gate_instance_to_unitary(gate: &pecos_core::Gate, qubits: &[QubitId]) -> Option { + let q0 = qubits.first().copied()?; match gate.gate_type { GateType::H => Some(unitary_rep::H(q0)), GateType::X => Some(unitary_rep::X(q0)), @@ -1749,38 +1831,38 @@ mod tests { Some(unitary_rep::RZ(angle, q0)) } GateType::CX => { - let q1 = gate.qubits.get(1).copied()?; + let q1 = qubits.get(1).copied()?; Some(unitary_rep::CX(q0, q1)) } GateType::CY => { - let q1 = gate.qubits.get(1).copied()?; + let q1 = qubits.get(1).copied()?; Some(unitary_rep::CY(q0, q1)) } GateType::CZ => { - let q1 = gate.qubits.get(1).copied()?; + let q1 = qubits.get(1).copied()?; Some(unitary_rep::CZ(q0, q1)) } GateType::RXX => { - let q1 = gate.qubits.get(1).copied()?; + let q1 = qubits.get(1).copied()?; let angle = *gate.angles.first()?; Some(unitary_rep::RXX(angle, q0, q1)) } GateType::RYY => { - let q1 = gate.qubits.get(1).copied()?; + let q1 = qubits.get(1).copied()?; let angle = *gate.angles.first()?; Some(unitary_rep::RYY(angle, q0, q1)) } GateType::RZZ => { - let q1 = gate.qubits.get(1).copied()?; + let q1 = qubits.get(1).copied()?; let angle = *gate.angles.first()?; Some(unitary_rep::RZZ(angle, q0, q1)) } GateType::SZZ => { - let q1 = gate.qubits.get(1).copied()?; + let q1 = qubits.get(1).copied()?; Some(unitary_rep::SZZ(q0, q1)) } GateType::SZZdg => { - let q1 = gate.qubits.get(1).copied()?; + let q1 = qubits.get(1).copied()?; Some(unitary_rep::SZZ(q0, q1).dg()) } GateType::I | GateType::Idle => Some(unitary_rep::I(q0)), @@ -2535,17 +2617,6 @@ mod tests { // -- Circuit 3: Inverse cancellation (from circuit composition) -- let mut c3 = TickCircuit::new(); - // Subcircuit A applies some basis change - c3.tick().h(&[0, 1]); - c3.tick().sx(&[0]).t(&[1]); - c3.tick().cx(&[(0, 1)]); - // Subcircuit B undoes the basis change then does something else - c3.tick().cx(&[(0, 1)]); - c3.ticks_mut()[3].add_gate(Gate::sxdg(&[0])); - c3.ticks_mut()[3].add_gate(Gate::tdg(&[1])); - // Wait, this won't cancel because CX is between SX and SXdg on different ticks. - // Let me restructure: undo in reverse order - let mut c3 = TickCircuit::new(); c3.tick().h(&[0, 1]); c3.tick().t(&[0]).sx(&[1]); c3.tick().cx(&[(0, 1)]); @@ -2759,6 +2830,54 @@ mod tests { assert_eq!(gates[2].gate_type, GateType::Z); } + #[test] + fn peephole_tick_preserves_metadata_when_splitting_batched_commands() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[1]); + tc.tick() + .cx(&[(0, 1), (2, 3)]) + .meta("calibration", Attribute::String("entangler".into())); + tc.tick().h(&[1]); + + PeepholeOptimize.apply_tick(&mut tc); + + let middle = tc + .ticks() + .iter() + .find(|tick| !tick.gates().is_empty()) + .expect("peephole result should keep the middle tick"); + assert_eq!(middle.len(), 2); + assert_eq!(middle.gate_count(), 2); + + let mut saw_rewritten = false; + let mut saw_untouched = false; + for (idx, gate) in middle.gates().iter().enumerate() { + assert_eq!( + middle.get_gate_attr(idx, "calibration"), + Some(&Attribute::String("entangler".into())) + ); + match gate.gate_type { + GateType::CZ => { + saw_rewritten = true; + assert_eq!( + gate.qubits.as_slice(), + &[QubitId::from(0), QubitId::from(1)] + ); + } + GateType::CX => { + saw_untouched = true; + assert_eq!( + gate.qubits.as_slice(), + &[QubitId::from(2), QubitId::from(3)] + ); + } + other => panic!("unexpected gate after peephole optimization: {other:?}"), + } + } + assert!(saw_rewritten); + assert!(saw_untouched); + } + #[test] fn peephole_tick_multiple_patterns() { // Two independent H-CX-H patterns diff --git a/crates/pecos-quantum/src/pauli_sequence.rs b/crates/pecos-quantum/src/pauli_sequence.rs index ab8965baf..355d5fe87 100644 --- a/crates/pecos-quantum/src/pauli_sequence.rs +++ b/crates/pecos-quantum/src/pauli_sequence.rs @@ -1239,6 +1239,24 @@ mod tests { assert!(groups.iter().all(PauliSequence::is_abelian)); } + #[test] + fn group_commuting_handles_empty_single_and_all_commuting_inputs() { + let empty = PauliSequence::new(Vec::new()); + assert!(empty.group_commuting().is_empty()); + + let single = PauliSequence::new(vec![X(3)]); + let single_groups = single.group_commuting(); + assert_eq!(single_groups.len(), 1); + assert_eq!(single_groups[0].paulis(), &[X(3)]); + assert!(single_groups[0].is_abelian()); + + let commuting = PauliSequence::new(vec![Z(0), Z(1), Zs([0, 1]), X(2)]); + let commuting_groups = commuting.group_commuting(); + assert_eq!(commuting_groups.len(), 1); + assert_eq!(commuting_groups[0].paulis(), commuting.paulis()); + assert!(commuting_groups[0].is_abelian()); + } + #[test] fn test_row_reduce() { // ZIZ = ZZI * IZZ, so one generator is redundant diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index eee2226d3..b960b700f 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -211,6 +211,53 @@ impl fmt::Display for QubitConflictError { impl std::error::Error for QubitConflictError {} +/// Error when trying to add a gate to a tick. +#[derive(Debug, Clone, PartialEq, Eq)] +pub enum TickGateError { + /// The gate payload itself is invalid. + InvalidGate { + /// Validation error from [`Gate::validate`]. + message: String, + /// The tick index where the invalid gate was being inserted. + tick_idx: Option, + }, + /// The gate is valid, but overlaps a qubit already used in this tick. + QubitConflict(QubitConflictError), +} + +impl TickGateError { + fn set_tick_idx(&mut self, tick_idx: usize) { + match self { + Self::InvalidGate { tick_idx: idx, .. } => *idx = Some(tick_idx), + Self::QubitConflict(err) => err.tick_idx = Some(tick_idx), + } + } +} + +impl fmt::Display for TickGateError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + Self::InvalidGate { + message, + tick_idx: Some(tick_idx), + } => write!(f, "Invalid gate in tick {tick_idx}: {message}"), + Self::InvalidGate { + message, + tick_idx: None, + } => write!(f, "Invalid gate: {message}"), + Self::QubitConflict(err) => write!(f, "{err}"), + } + } +} + +impl std::error::Error for TickGateError {} + +impl From for TickGateError { + fn from(e: QubitConflictError) -> Self { + Self::QubitConflict(e) + } +} + /// Error when a custom gate is used with a different signature than previously established. #[derive(Debug, Clone, PartialEq, Eq)] pub struct GateSignatureMismatchError { @@ -241,6 +288,7 @@ impl std::error::Error for GateSignatureMismatchError {} #[derive(Debug, Clone)] pub enum CustomGateError { SignatureMismatch(GateSignatureMismatchError), + InvalidGate(String), QubitConflict(QubitConflictError), } @@ -248,6 +296,7 @@ impl fmt::Display for CustomGateError { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { match self { Self::SignatureMismatch(e) => write!(f, "{e}"), + Self::InvalidGate(e) => write!(f, "{e}"), Self::QubitConflict(e) => write!(f, "{e}"), } } @@ -267,6 +316,15 @@ impl From for CustomGateError { } } +impl From for CustomGateError { + fn from(e: TickGateError) -> Self { + match e { + TickGateError::InvalidGate { message, .. } => Self::InvalidGate(message), + TickGateError::QubitConflict(err) => Self::QubitConflict(err), + } + } +} + /// A single time slice containing gates that execute in parallel. #[derive(Debug, Clone, Default)] pub struct Tick { @@ -278,6 +336,15 @@ pub struct Tick { attrs: BTreeMap, } +#[derive(Debug, Clone, Copy)] +struct GateBatchPiece { + gate_idx: usize, + qubit_start: usize, + qubit_len: usize, + meas_id_start: usize, + meas_id_len: usize, +} + impl Tick { /// Create a new empty tick. #[must_use] @@ -286,11 +353,40 @@ impl Tick { } /// Get the number of gates in this tick. + /// + /// This is the number of stored gate commands. Batched commands such as + /// `cx(&[(0, 1), (2, 3)])` count as one stored command. #[must_use] pub fn len(&self) -> usize { self.gates.len() } + /// Get the number of individual gates in this tick. + #[must_use] + pub fn gate_count(&self) -> usize { + self.gates.iter().map(Gate::num_gates).sum() + } + + /// Get the number of compatible gate batches in this tick. + /// + /// Gates with the same type, parameters, payload shape, and metadata can + /// execute as one batch when they differ only by disjoint qubits. + #[must_use] + pub fn gate_batch_count(&self) -> usize { + let mut representative_indices: Vec = Vec::new(); + 'gate: for (idx, gate) in self.gates.iter().enumerate() { + for &rep_idx in &representative_indices { + if self.gate_attrs_equivalent(rep_idx, idx) + && self.gates[rep_idx].can_batch_with(gate) + { + continue 'gate; + } + } + representative_indices.push(idx); + } + representative_indices.len() + } + /// Check if the tick is empty. #[must_use] pub fn is_empty(&self) -> bool { @@ -309,23 +405,185 @@ impl Tick { } /// Add a gate to this tick. + /// + /// # Panics + /// + /// Panics if [`Gate::validate`] rejects the gate payload or if the gate + /// conflicts with an existing gate in this tick. Use + /// [`try_add_gate`](Self::try_add_gate) for fallible insertion. pub fn add_gate(&mut self, gate: Gate) -> usize { + self.try_add_gate(gate) + .unwrap_or_else(|err| panic!("{err}")) + } + + fn push_gate_unchecked(&mut self, gate: Gate) -> usize { let idx = self.gates.len(); self.gates.push(gate); idx } + fn push_gate_unchecked_piece(&mut self, gate: Gate) -> GateBatchPiece { + let qubit_len = gate.qubits.len(); + let meas_id_len = gate.meas_ids.len(); + let gate_idx = self.push_gate_unchecked(gate); + GateBatchPiece { + gate_idx, + qubit_start: 0, + qubit_len, + meas_id_start: 0, + meas_id_len, + } + } + + fn normalized_gate_attrs(&self, gate_idx: usize) -> Option<&BTreeMap> { + self.gate_attrs + .get(&gate_idx) + .filter(|attrs| !attrs.is_empty()) + } + + fn gate_attrs_equivalent(&self, a: usize, b: usize) -> bool { + self.normalized_gate_attrs(a) == self.normalized_gate_attrs(b) + } + + fn gate_has_no_attrs(&self, gate_idx: usize) -> bool { + self.normalized_gate_attrs(gate_idx).is_none() + } + + fn compatible_empty_attr_batch(&self, gate: &Gate) -> Option { + self.gates + .iter() + .enumerate() + .find(|(idx, existing)| self.gate_has_no_attrs(*idx) && existing.can_batch_with(gate)) + .map(|(idx, _)| idx) + } + + fn whole_gate_piece(&self, gate_idx: usize) -> GateBatchPiece { + let gate = &self.gates[gate_idx]; + GateBatchPiece { + gate_idx, + qubit_start: 0, + qubit_len: gate.qubits.len(), + meas_id_start: 0, + meas_id_len: gate.meas_ids.len(), + } + } + + fn merge_compatible_piece_at(&mut self, piece: GateBatchPiece) -> GateBatchPiece { + if piece.gate_idx >= self.gates.len() { + return piece; + } + + let Some(target_idx) = (0..piece.gate_idx).find(|&idx| { + self.gate_attrs_equivalent(idx, piece.gate_idx) + && self.gates[idx].can_batch_with(&self.gates[piece.gate_idx]) + }) else { + return piece; + }; + + let qubit_start = self.gates[target_idx].qubits.len(); + let meas_id_start = self.gates[target_idx].meas_ids.len(); + let gate = self.gates[piece.gate_idx].clone(); + self.gates[target_idx].append_batch(gate); + self.remove_gate(piece.gate_idx); + GateBatchPiece { + gate_idx: target_idx, + qubit_start, + qubit_len: piece.qubit_len, + meas_id_start, + meas_id_len: piece.meas_id_len, + } + } + + fn merge_compatible_gate_at(&mut self, gate_idx: usize) -> usize { + if gate_idx >= self.gates.len() { + return gate_idx; + } + self.merge_compatible_piece_at(self.whole_gate_piece(gate_idx)) + .gate_idx + } + + fn isolate_batch_piece(&mut self, piece: GateBatchPiece) -> usize { + if piece.gate_idx >= self.gates.len() { + return piece.gate_idx; + } + + let gate_qubit_len = self.gates[piece.gate_idx].qubits.len(); + let gate_meas_id_len = self.gates[piece.gate_idx].meas_ids.len(); + if piece.qubit_start == 0 + && piece.qubit_len == gate_qubit_len + && piece.meas_id_start == 0 + && piece.meas_id_len == gate_meas_id_len + { + return piece.gate_idx; + } + + assert_eq!( + piece.qubit_start + piece.qubit_len, + gate_qubit_len, + "batched gate metadata can only split the appended suffix" + ); + assert_eq!( + piece.meas_id_start + piece.meas_id_len, + gate_meas_id_len, + "batched gate metadata can only split the appended measurement-id suffix" + ); + + let mut split_gate = self.gates[piece.gate_idx].clone(); + split_gate.qubits = self.gates[piece.gate_idx].qubits[piece.qubit_start..].into(); + split_gate.meas_ids = self.gates[piece.gate_idx].meas_ids[piece.meas_id_start..].into(); + + self.gates[piece.gate_idx] + .qubits + .truncate(piece.qubit_start); + self.gates[piece.gate_idx] + .meas_ids + .truncate(piece.meas_id_start); + + let split_idx = self.push_gate_unchecked(split_gate); + if let Some(attrs) = self.gate_attrs.get(&piece.gate_idx).cloned() { + self.gate_attrs.insert(split_idx, attrs); + } + split_idx + } + + fn set_gate_attr_for_piece( + &mut self, + piece: GateBatchPiece, + key: &str, + value: Attribute, + ) -> GateBatchPiece { + let gate_idx = self.isolate_batch_piece(piece); + self.set_gate_attr(gate_idx, key, value); + self.merge_compatible_piece_at(self.whole_gate_piece(gate_idx)) + } + + fn set_gate_attrs_for_piece( + &mut self, + piece: GateBatchPiece, + attrs: BTreeMap, + ) -> GateBatchPiece { + let gate_idx = self.isolate_batch_piece(piece); + self.set_gate_attrs(gate_idx, attrs); + self.merge_compatible_piece_at(self.whole_gate_piece(gate_idx)) + } + /// Set metadata on a gate. - pub fn set_gate_attr(&mut self, gate_idx: usize, key: &str, value: Attribute) { + /// + /// Returns the gate index. + pub fn set_gate_attr(&mut self, gate_idx: usize, key: &str, value: Attribute) -> usize { self.gate_attrs .entry(gate_idx) .or_default() .insert(key.to_string(), value); + gate_idx } /// Set multiple metadata attributes on a gate at once. - pub fn set_gate_attrs(&mut self, gate_idx: usize, attrs: BTreeMap) { + /// + /// Returns the gate index. + pub fn set_gate_attrs(&mut self, gate_idx: usize, attrs: BTreeMap) -> usize { self.gate_attrs.entry(gate_idx).or_default().extend(attrs); + gate_idx } /// Get metadata from a gate. @@ -393,20 +651,68 @@ impl Tick { .collect() } - /// Try to add a gate to this tick, returning an error if any qubit is already in use. + /// Try to add a gate to this tick. /// /// # Errors /// - /// Returns `QubitConflictError` if any qubit in the gate is already used by another gate in this tick. - pub fn try_add_gate(&mut self, gate: Gate) -> Result { + /// Returns [`TickGateError::InvalidGate`] if the gate payload is invalid, or + /// [`TickGateError::QubitConflict`] if any qubit in the gate is already used + /// by another gate in this tick. + pub(crate) fn try_add_gate_preserving_command( + &mut self, + gate: Gate, + ) -> Result { + gate.validate() + .map_err(|message| TickGateError::InvalidGate { + message, + tick_idx: None, + })?; let conflicts = self.find_conflicts(&gate.qubits); if !conflicts.is_empty() { - return Err(QubitConflictError { + return Err(TickGateError::QubitConflict(QubitConflictError { conflicting_qubits: conflicts, tick_idx: None, - }); + })); + } + Ok(self.push_gate_unchecked(gate)) + } + + /// Try to add a gate to this tick. + /// + /// # Errors + /// + /// Returns [`TickGateError::InvalidGate`] if the gate payload is invalid, or + /// [`TickGateError::QubitConflict`] if any qubit in the gate is already used + /// by another gate in this tick. + pub fn try_add_gate(&mut self, gate: Gate) -> Result { + self.try_add_gate_piece(gate).map(|piece| piece.gate_idx) + } + + fn try_add_gate_piece(&mut self, gate: Gate) -> Result { + gate.validate() + .map_err(|message| TickGateError::InvalidGate { + message, + tick_idx: None, + })?; + let conflicts = self.find_conflicts(&gate.qubits); + if !conflicts.is_empty() { + return Err(TickGateError::QubitConflict(QubitConflictError { + conflicting_qubits: conflicts, + tick_idx: None, + })); + } + if let Some(gate_idx) = self.compatible_empty_attr_batch(&gate) { + let piece = GateBatchPiece { + gate_idx, + qubit_start: self.gates[gate_idx].qubits.len(), + qubit_len: gate.qubits.len(), + meas_id_start: self.gates[gate_idx].meas_ids.len(), + meas_id_len: gate.meas_ids.len(), + }; + self.gates[gate_idx].append_batch(gate); + return Ok(piece); } - Ok(self.add_gate(gate)) + Ok(self.push_gate_unchecked_piece(gate)) } /// Remove all gates that use any of the specified qubits. @@ -608,6 +914,7 @@ pub struct TickHandle<'a> { circuit: &'a mut TickCircuit, tick_idx: usize, last_gate_idx: Option, + last_gate_piece: Option, } /// Handle returned by preparation operations on a tick. @@ -617,7 +924,7 @@ pub struct TickHandle<'a> { pub struct TickPrepHandle<'a> { circuit: &'a mut TickCircuit, tick_idx: usize, - gate_idx: usize, + gate_piece: GateBatchPiece, } impl TickPrepHandle<'_> { @@ -626,7 +933,7 @@ impl TickPrepHandle<'_> { /// Returns `()` to break the chain. pub fn meta(self, key: &str, value: impl Into) { if let Some(tick) = self.circuit.get_tick_mut(self.tick_idx) { - tick.set_gate_attr(self.gate_idx, key, value.into()); + tick.set_gate_attr_for_piece(self.gate_piece, key, value.into()); } } @@ -635,7 +942,7 @@ impl TickPrepHandle<'_> { /// Returns `()` to break the chain. pub fn metas(self, attrs: BTreeMap) { if let Some(tick) = self.circuit.get_tick_mut(self.tick_idx) { - tick.set_gate_attrs(self.gate_idx, attrs); + tick.set_gate_attrs_for_piece(self.gate_piece, attrs); } } } @@ -647,7 +954,7 @@ impl TickPrepHandle<'_> { pub struct TickMeasureHandle<'a> { circuit: &'a mut TickCircuit, tick_idx: usize, - gate_idx: usize, + gate_piece: GateBatchPiece, } impl TickMeasureHandle<'_> { @@ -656,7 +963,7 @@ impl TickMeasureHandle<'_> { /// Returns `()` to break the chain. pub fn meta(self, key: &str, value: impl Into) { if let Some(tick) = self.circuit.get_tick_mut(self.tick_idx) { - tick.set_gate_attr(self.gate_idx, key, value.into()); + tick.set_gate_attr_for_piece(self.gate_piece, key, value.into()); } } @@ -665,7 +972,7 @@ impl TickMeasureHandle<'_> { /// Returns `()` to break the chain. pub fn metas(self, attrs: BTreeMap) { if let Some(tick) = self.circuit.get_tick_mut(self.tick_idx) { - tick.set_gate_attrs(self.gate_idx, attrs); + tick.set_gate_attrs_for_piece(self.gate_piece, attrs); } } } @@ -702,14 +1009,53 @@ impl TickCircuit { } /// Get the total number of gates across all ticks. + /// + /// Batched commands count by individual gate. For example, + /// `cx(&[(0, 1), (2, 3)])` contributes two gates. + /// + /// # Examples + /// + /// ``` + /// use pecos_quantum::TickCircuit; + /// + /// let mut circuit = TickCircuit::new(); + /// circuit.tick().h(&[0, 1, 2]); + /// circuit.tick().cx(&[(0, 1), (2, 3)]); + /// + /// assert_eq!(circuit.gate_count(), 5); + /// assert_eq!(circuit.gate_batch_count(), 2); + /// ``` #[must_use] pub fn gate_count(&self) -> usize { - self.ticks.iter().map(Tick::len).sum() + self.ticks.iter().map(Tick::gate_count).sum() + } + + /// Get the total number of compatible gate batches across all ticks. + /// + /// A batch is a stored command group that can execute together because the + /// gates are identical except for disjoint qubit support and compatible + /// metadata. + /// + /// # Examples + /// + /// ``` + /// use pecos_quantum::TickCircuit; + /// + /// let mut circuit = TickCircuit::new(); + /// circuit.tick().h(&[0]).h(&[1]).cx(&[(2, 3), (4, 5)]); + /// + /// assert_eq!(circuit.gate_count(), 4); + /// assert_eq!(circuit.gate_batch_count(), 2); // one H batch, one CX batch + /// ``` + #[must_use] + pub fn gate_batch_count(&self) -> usize { + self.ticks.iter().map(Tick::gate_batch_count).sum() } /// Convert a per-tick gate index to a global gate index. /// - /// Global index = sum of gate counts for all ticks before `tick_idx` + `gate_idx`. + /// Global index = sum of stored gate commands for all ticks before + /// `tick_idx` + `gate_idx`. #[must_use] pub fn global_gate_index(&self, tick_idx: usize, gate_idx: usize) -> usize { self.ticks[..tick_idx].iter().map(Tick::len).sum::() + gate_idx @@ -863,6 +1209,7 @@ impl TickCircuit { circuit: self, tick_idx, last_gate_idx: None, + last_gate_piece: None, } } @@ -1173,6 +1520,7 @@ impl TickCircuit { circuit: self, tick_idx: idx, last_gate_idx: None, + last_gate_piece: None, } } @@ -1212,6 +1560,7 @@ impl TickCircuit { circuit: self, tick_idx: idx, last_gate_idx: None, + last_gate_piece: None, } } @@ -1352,7 +1701,8 @@ impl TickCircuit { /// /// let mut circuit = TickCircuit::new(); /// circuit.tick().h(&[0, 1, 2]); - /// circuit.tick().cx(&[(0, 1), (1, 2)]); + /// circuit.tick().cx(&[(0, 1)]); + /// circuit.tick().cx(&[(1, 2)]); /// /// for (tick_idx, tick) in circuit.iter_ticks() { /// println!("Tick {} has {} gates", tick_idx, tick.len()); @@ -1405,7 +1755,9 @@ impl TickCircuit { /// Count gates by type across the entire circuit. /// - /// Returns a map from `GateType` to count. + /// Returns a map from `GateType` to gate count. Batched commands + /// such as `cx(&[(0, 1), (2, 3)])` count as two CX gates even though they + /// are stored as one [`Gate`] carrying two disjoint pairs. /// /// # Examples /// @@ -1414,18 +1766,18 @@ impl TickCircuit { /// use pecos_core::gate_type::GateType; /// /// let mut circuit = TickCircuit::new(); - /// circuit.tick().h(&[0, 1, 2]); - /// circuit.tick().cx(&[(0, 1), (1, 2)]); + /// circuit.tick().h(&[0, 1, 2, 3]); + /// circuit.tick().cx(&[(0, 1), (2, 3)]); /// /// let counts = circuit.gate_counts_by_type(); - /// assert_eq!(counts.get(&GateType::H), Some(&1)); // 1 H gate object (with 3 qubits) - /// assert_eq!(counts.get(&GateType::CX), Some(&1)); // 1 CX gate object (with 2 pairs) + /// assert_eq!(counts.get(&GateType::H), Some(&4)); // 4 H gates + /// assert_eq!(counts.get(&GateType::CX), Some(&2)); // 2 CX gates /// ``` #[must_use] pub fn gate_counts_by_type(&self) -> BTreeMap { let mut counts = BTreeMap::new(); for gate in self.iter_gates() { - *counts.entry(gate.gate_type).or_insert(0) += 1; + *counts.entry(gate.gate_type).or_insert(0) += gate.num_gates(); } counts } @@ -1577,6 +1929,12 @@ impl TickCircuit { /// metadata from merged ticks is dropped (the target tick's metadata /// wins). /// + /// # Panics + /// + /// Panics if an existing gate in the circuit fails validation while being + /// moved into its compacted tick. Circuits built through `TickCircuit` + /// constructors already validate gates at insertion time. + /// /// # Example /// /// ``` @@ -1627,11 +1985,14 @@ impl TickCircuit { if all_clear { // Move gates and their per-gate metadata into the target tick. for (gi, gate) in tick.gates.iter().enumerate() { - let new_idx = compacted[target_idx].add_gate(gate.clone()); if let Some(attrs) = tick.gate_attrs.get(&gi) { - compacted[target_idx] - .gate_attrs - .insert(new_idx, attrs.clone()); + let new_idx = compacted[target_idx] + .try_add_gate_preserving_command(gate.clone()) + .unwrap_or_else(|err| panic!("{err}")); + compacted[target_idx].set_gate_attrs(new_idx, attrs.clone()); + compacted[target_idx].merge_compatible_gate_at(new_idx); + } else { + compacted[target_idx].add_gate(gate.clone()); } } placed = true; @@ -1663,34 +2024,39 @@ impl<'a> TickHandle<'a> { /// /// # Panics /// - /// Panics if any qubit in the gate is already used by another gate in this tick. + /// Panics if the gate payload is invalid or any qubit in the gate is + /// already used by another gate in this tick. /// Use `try_add_gate` for fallible gate addition. fn add_gate(&mut self, gate: Gate) -> &mut Self { - match self.circuit.ticks[self.tick_idx].try_add_gate(gate) { - Ok(idx) => { - self.last_gate_idx = Some(idx); + match self.circuit.ticks[self.tick_idx].try_add_gate_piece(gate) { + Ok(piece) => { + self.last_gate_idx = Some(piece.gate_idx); + self.last_gate_piece = Some(piece); self } Err(mut err) => { - err.tick_idx = Some(self.tick_idx); + err.set_tick_idx(self.tick_idx); panic!("{}", err); } } } - /// Try to add a gate to this tick, returning an error if any qubit is already in use. + /// Try to add a gate to this tick. /// /// # Errors /// - /// Returns `QubitConflictError` if any qubit in the gate is already used by another gate in this tick. - pub fn try_add_gate(&mut self, gate: Gate) -> Result<&mut Self, QubitConflictError> { - match self.circuit.ticks[self.tick_idx].try_add_gate(gate) { - Ok(idx) => { - self.last_gate_idx = Some(idx); + /// Returns [`TickGateError::InvalidGate`] if the gate payload is invalid, or + /// [`TickGateError::QubitConflict`] if any qubit in the gate is already used + /// by another gate in this tick. + pub fn try_add_gate(&mut self, gate: Gate) -> Result<&mut Self, TickGateError> { + match self.circuit.ticks[self.tick_idx].try_add_gate_piece(gate) { + Ok(piece) => { + self.last_gate_idx = Some(piece.gate_idx); + self.last_gate_piece = Some(piece); Ok(self) } Err(mut err) => { - err.tick_idx = Some(self.tick_idx); + err.set_tick_idx(self.tick_idx); Err(err) } } @@ -1700,26 +2066,35 @@ impl<'a> TickHandle<'a> { /// /// # Panics /// - /// Panics if any qubit in the gate is already used by another gate in this tick. - fn add_gate_get_idx(&mut self, gate: Gate) -> usize { - match self.circuit.ticks[self.tick_idx].try_add_gate(gate) { - Ok(idx) => { - self.last_gate_idx = Some(idx); - idx + /// Panics if the gate payload is invalid or any qubit in the gate is + /// already used by another gate in this tick. + fn add_gate_get_piece(&mut self, gate: Gate) -> GateBatchPiece { + match self.circuit.ticks[self.tick_idx].try_add_gate_piece(gate) { + Ok(piece) => { + self.last_gate_idx = Some(piece.gate_idx); + self.last_gate_piece = Some(piece); + piece } Err(mut err) => { - err.tick_idx = Some(self.tick_idx); + err.set_tick_idx(self.tick_idx); panic!("{}", err); } } } + fn add_gate_get_idx(&mut self, gate: Gate) -> usize { + self.add_gate_get_piece(gate).gate_idx + } + /// Set metadata on the last added gate. /// /// If no gate has been added yet, sets tick-level metadata instead. pub fn meta(&mut self, key: &str, value: impl Into) -> &mut Self { - if let Some(gate_idx) = self.last_gate_idx { - self.circuit.ticks[self.tick_idx].set_gate_attr(gate_idx, key, value.into()); + if let Some(piece) = self.last_gate_piece { + let piece = + self.circuit.ticks[self.tick_idx].set_gate_attr_for_piece(piece, key, value.into()); + self.last_gate_idx = Some(piece.gate_idx); + self.last_gate_piece = Some(piece); } else { // No gate yet - set tick-level metadata self.circuit.ticks[self.tick_idx].set_attr(key, value.into()); @@ -1731,8 +2106,10 @@ impl<'a> TickHandle<'a> { /// /// If no gate has been added yet, sets tick-level metadata instead. pub fn metas(&mut self, attrs: BTreeMap) -> &mut Self { - if let Some(gate_idx) = self.last_gate_idx { - self.circuit.ticks[self.tick_idx].set_gate_attrs(gate_idx, attrs); + if let Some(piece) = self.last_gate_piece { + let piece = self.circuit.ticks[self.tick_idx].set_gate_attrs_for_piece(piece, attrs); + self.last_gate_idx = Some(piece.gate_idx); + self.last_gate_piece = Some(piece); } else { // No gate yet - set tick-level metadata self.circuit.ticks[self.tick_idx].set_attrs(attrs); @@ -2172,11 +2549,13 @@ impl<'a> TickHandle<'a> { /// circuit.tick().pz(&[1, 2, 3]); // Multiple qubits /// ``` pub fn pz(mut self, qubits: &[impl Into + Copy]) -> TickPrepHandle<'a> { - let gate_idx = self.add_gate_get_idx(Gate::pz(qubits)); + let gate_piece = self.add_gate_get_piece(Gate::pz(qubits)); + self.last_gate_idx = None; + self.last_gate_piece = None; TickPrepHandle { circuit: self.circuit, tick_idx: self.tick_idx, - gate_idx, + gate_piece, } } @@ -2196,23 +2575,24 @@ impl<'a> TickHandle<'a> { /// ``` pub fn mz(mut self, qubits: &[impl Into + Copy]) -> Vec { let mut gate = Gate::mz(qubits); - let refs: Vec = qubits - .iter() - .map(|&q| { - let record_idx = self.circuit.next_meas_record; - let mr = MeasId(record_idx); - self.circuit.next_meas_record += 1; - gate.meas_ids.push(mr); - TickMeasRef { - tick: self.tick_idx, - gate_idx: 0, // placeholder, updated below - qubit: q.into(), - record_idx, - meas_id: mr, - } - }) - .collect(); + let mut refs = Vec::with_capacity(qubits.len()); + for &q in qubits { + let tick_idx = self.tick_idx; + let record_idx = self.circuit.next_meas_record; + self.circuit.next_meas_record += 1; + let mr = MeasId(record_idx); + gate.meas_ids.push(mr); + refs.push(TickMeasRef { + tick: tick_idx, + gate_idx: 0, // placeholder, updated below + qubit: q.into(), + record_idx, + meas_id: mr, + }); + } let gate_idx = self.add_gate_get_idx(gate); + self.last_gate_idx = None; + self.last_gate_piece = None; // Fix up gate_idx in refs (needed because we had to build gate before adding) refs.into_iter() .map(|mut r| { @@ -2236,23 +2616,24 @@ impl<'a> TickHandle<'a> { /// ``` pub fn mz_free(mut self, qubits: &[impl Into + Copy]) -> Vec { let mut gate = Gate::mz_free(qubits); - let refs: Vec = qubits - .iter() - .map(|&q| { - let record_idx = self.circuit.next_meas_record; - let mr = MeasId(record_idx); - self.circuit.next_meas_record += 1; - gate.meas_ids.push(mr); - TickMeasRef { - tick: self.tick_idx, - gate_idx: 0, - qubit: q.into(), - record_idx, - meas_id: mr, - } - }) - .collect(); + let mut refs = Vec::with_capacity(qubits.len()); + for &q in qubits { + let tick_idx = self.tick_idx; + let record_idx = self.circuit.next_meas_record; + self.circuit.next_meas_record += 1; + let mr = MeasId(record_idx); + gate.meas_ids.push(mr); + refs.push(TickMeasRef { + tick: tick_idx, + gate_idx: 0, + qubit: q.into(), + record_idx, + meas_id: mr, + }); + } let gate_idx = self.add_gate_get_idx(gate); + self.last_gate_idx = None; + self.last_gate_piece = None; refs.into_iter() .map(|mut r| { r.gate_idx = gate_idx; @@ -2336,20 +2717,21 @@ impl<'a> TickHandle<'a> { let qubit_ids: GateQubits = qubits.iter().map(|&q| QubitId::from(q)).collect(); let gate = Gate::new(GateType::Custom, angles.to_vec(), vec![], qubit_ids); - match self.circuit.ticks[self.tick_idx].try_add_gate(gate) { - Ok(idx) => { - self.last_gate_idx = Some(idx); + match self.circuit.ticks[self.tick_idx].try_add_gate_piece(gate) { + Ok(piece) => { // Auto-store _symbol metadata - self.circuit.ticks[self.tick_idx].set_gate_attr( - idx, + let piece = self.circuit.ticks[self.tick_idx].set_gate_attr_for_piece( + piece, "_symbol", Attribute::String(name.to_string()), ); + self.last_gate_idx = Some(piece.gate_idx); + self.last_gate_piece = Some(piece); Ok(self) } Err(mut err) => { - err.tick_idx = Some(self.tick_idx); - Err(CustomGateError::QubitConflict(err)) + err.set_tick_idx(self.tick_idx); + Err(err.into()) } } } @@ -2377,30 +2759,63 @@ impl From<&DagCircuit> for TickCircuit { /// ``` fn from(dag: &DagCircuit) -> Self { let mut tc = TickCircuit::new(); + let mut dag_node_to_record_indices: BTreeMap> = BTreeMap::new(); + let mut next_meas_record = 0usize; for layer in dag.layers() { - // Allocate a new tick for this layer - let tick_idx = { - let handle = tc.tick(); - handle.index() - }; - - // Add all gates in this layer to the tick - if let Some(tick) = tc.get_tick_mut(tick_idx) { - for node_id in layer { - if let Some(gate) = dag.gate(node_id) { - let gate_idx = tick.add_gate(gate.clone()); - - // Copy gate attributes - if let Some(attrs) = dag.gate_attrs(node_id) { - for (key, value) in attrs { - tick.set_gate_attr(gate_idx, key, value.clone()); + let mut layer_ticks = vec![Tick::new()]; + + for node_id in layer { + if let Some(gate) = dag.gate(node_id) { + let mut gate = gate.clone(); + if matches!( + gate.gate_type, + GateType::MZ | GateType::MeasureFree | GateType::MeasureLeaked + ) { + if gate.meas_ids.is_empty() { + let mut records = Vec::with_capacity(gate.qubits.len()); + for _ in &gate.qubits { + let record_idx = next_meas_record; + next_meas_record += 1; + gate.meas_ids.push(MeasId(record_idx)); + records.push(record_idx); + } + dag_node_to_record_indices.insert(node_id, records); + } else { + let records: Vec = + gate.meas_ids.iter().map(|meas_id| meas_id.0).collect(); + if let Some(next) = records.iter().max().map(|record| record + 1) { + next_meas_record = next_meas_record.max(next); } + dag_node_to_record_indices.insert(node_id, records); } } + + let target_idx = layer_ticks + .iter() + .position(|tick| tick.find_conflicts(&gate.qubits).is_empty()) + .unwrap_or_else(|| { + layer_ticks.push(Tick::new()); + layer_ticks.len() - 1 + }); + let tick = &mut layer_ticks[target_idx]; + // Copy gate attributes + if let Some(attrs) = dag.gate_attrs(node_id) { + let gate_idx = tick + .try_add_gate_preserving_command(gate) + .unwrap_or_else(|err| panic!("{err}")); + tick.set_gate_attrs(gate_idx, attrs.clone()); + tick.merge_compatible_gate_at(gate_idx); + } else { + tick.add_gate(gate); + } } } + + tc.ticks.extend(layer_ticks); } + tc.next_tick = tc.ticks.len(); + tc.next_meas_record = next_meas_record; // Copy circuit-level attributes, restoring tick-level attrs from prefixed keys let tick_attr_prefix = "tick["; @@ -2422,17 +2837,62 @@ impl From<&DagCircuit> for TickCircuit { } } - // Transfer annotations (Pauli operators don't need node remapping - // since TickCircuit stores them without node references; - // Detector/Observable measurement_nodes are DAG node IDs which - // become gate_idx values in the TickCircuit -- the mapping is - // handled by the gate ordering within ticks) - tc.annotations = dag.annotations().to_vec(); + // Transfer annotations, remapping DAG measurement nodes to TickCircuit + // measurement record indices. Tracked operators have no measurement + // readout and keep their Pauli role unchanged. + tc.annotations = dag + .annotations() + .iter() + .map(|ann| { + let kind = match &ann.kind { + AnnotationKind::Detector { + measurement_nodes, + coords, + } => AnnotationKind::Detector { + measurement_nodes: remap_dag_measurement_nodes( + &dag_node_to_record_indices, + measurement_nodes, + ), + coords: coords.clone(), + }, + AnnotationKind::Observable { measurement_nodes } => { + AnnotationKind::Observable { + measurement_nodes: remap_dag_measurement_nodes( + &dag_node_to_record_indices, + measurement_nodes, + ), + } + } + AnnotationKind::TrackedOperator => AnnotationKind::TrackedOperator, + }; + PauliAnnotation { + pauli: ann.pauli.clone(), + kind, + label: ann.label.clone(), + } + }) + .collect(); tc } } +fn remap_dag_measurement_nodes( + dag_node_to_record_indices: &BTreeMap>, + measurement_nodes: &[usize], +) -> Vec { + measurement_nodes + .iter() + .flat_map(|node| { + dag_node_to_record_indices + .get(node) + .unwrap_or_else(|| panic!("annotation references non-measurement DAG node {node}")) + .iter() + .copied() + }) + .collect() +} + impl From for TickCircuit { fn from(dag: DagCircuit) -> Self { TickCircuit::from(&dag) @@ -2536,8 +2996,10 @@ impl From<&TickCircuit> for DagCircuit { vec![gate.clone()] }; + let mut split_nodes = Vec::with_capacity(split_gates.len()); for split_gate in &split_gates { let node = dag.add_gate(split_gate.clone()); + split_nodes.push(node); // For MZ gates, map each qubit's record to this node if split_gate.gate_type == GateType::MZ { @@ -2556,12 +3018,10 @@ impl From<&TickCircuit> for DagCircuit { } } - // Copy gate attributes (applied to last split gate) + // Copy batch-level gate attributes to every split gate. for (key, value) in tick.gate_attrs(gate_idx) { - if let Some(split_gate) = split_gates.last() { - let last_node_id = - *last_node.get(split_gate.qubits.first().unwrap()).unwrap(); - dag.set_gate_attr(last_node_id, key, value.clone()); + for &node in &split_nodes { + dag.set_gate_attr(node, key, value.clone()); } } } @@ -2659,7 +3119,7 @@ mod tests { tc.tick().mz(&[0, 1]); assert_eq!(tc.num_ticks(), 4); - assert_eq!(tc.gate_count(), 4); // 1 bulk prep, 1 H, 1 CX, 1 bulk measure + assert_eq!(tc.gate_count(), 6); // 2 preps, 1 H, 1 CX, 2 measurements // Check tick contents assert_eq!(tc.get_tick(0).unwrap().len(), 1); // One bulk prep gate @@ -2669,68 +3129,330 @@ mod tests { } #[test] - fn test_meta_on_gates() { + fn test_tick_construction_merges_compatible_gate_batches() { let mut tc = TickCircuit::new(); - - tc.tick() - .h(&[0]) - .meta("duration", Attribute::Float(50.0)) - .meta("error_rate", Attribute::Float(0.001)) - .x(&[1]) - .meta("duration", Attribute::Float(50.0)); + tc.tick().h(&[0]).h(&[1]).cx(&[(2, 3)]).cx(&[(4, 5)]); let tick = tc.get_tick(0).unwrap(); + assert_eq!(tick.len(), 2); // one H batch, one CX batch + assert_eq!(tick.gate_count(), 4); + assert_eq!(tick.gate_batch_count(), 2); + assert_eq!(tc.gate_count(), 4); + assert_eq!(tc.gate_batch_count(), 2); + + assert_eq!(tick.gates()[0].gate_type, GateType::H); assert_eq!( - tick.get_gate_attr(0, "duration"), - Some(&Attribute::Float(50.0)) + tick.gates()[0].qubits.as_slice(), + &[QubitId::from(0), QubitId::from(1)] ); + assert_eq!(tick.gates()[1].gate_type, GateType::CX); assert_eq!( - tick.get_gate_attr(0, "error_rate"), - Some(&Attribute::Float(0.001)) + tick.gates()[1].qubits.as_slice(), + &[ + QubitId::from(2), + QubitId::from(3), + QubitId::from(4), + QubitId::from(5) + ] ); + } + + #[test] + fn test_tick_construction_batches_only_same_metadata() { + let mut same = TickCircuit::new(); + { + let mut tick = same.tick(); + tick.h(&[0]) + .meta("calibration", Attribute::String("a".into())); + tick.h(&[1]) + .meta("calibration", Attribute::String("a".into())); + } + + let tick = same.get_tick(0).unwrap(); + assert_eq!(tick.len(), 1); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 1); assert_eq!( - tick.get_gate_attr(1, "duration"), - Some(&Attribute::Float(50.0)) + tick.get_gate_attr(0, "calibration"), + Some(&Attribute::String("a".into())) ); + + let mut different = TickCircuit::new(); + { + let mut tick = different.tick(); + tick.h(&[0]) + .meta("calibration", Attribute::String("a".into())); + tick.h(&[1]) + .meta("calibration", Attribute::String("b".into())); + } + + let tick = different.get_tick(0).unwrap(); + assert_eq!(tick.len(), 2); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 2); } #[test] - fn test_tick_meta() { + fn test_tick_construction_metadata_applies_to_last_gate_before_batching() { let mut tc = TickCircuit::new(); + { + let mut tick = tc.tick(); + tick.h(&[0]) + .h(&[1]) + .meta("calibration", Attribute::String("second".into())); + } - // meta() before any gates = tick-level metadata - tc.tick().meta("round", Attribute::Int(0)).h(&[0]); - tc.tick().meta("round", Attribute::Int(1)).cx(&[(0, 1)]); + let tick = tc.get_tick(0).unwrap(); + assert_eq!(tick.len(), 2); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 2); + assert_eq!(tick.gates()[0].qubits.as_slice(), &[QubitId::from(0)]); + assert_eq!(tick.gates()[1].qubits.as_slice(), &[QubitId::from(1)]); + assert_eq!(tick.get_gate_attr(0, "calibration"), None); + assert_eq!( + tick.get_gate_attr(1, "calibration"), + Some(&Attribute::String("second".into())) + ); + } + + #[test] + fn test_tick_construction_multiple_meta_calls_batch_after_completion() { + let mut tc = TickCircuit::new(); + { + let mut tick = tc.tick(); + tick.h(&[0]) + .meta("calibration", Attribute::String("a".into())) + .meta("role", Attribute::String("drive".into())); + tick.h(&[1]) + .meta("calibration", Attribute::String("a".into())) + .meta("role", Attribute::String("drive".into())); + } + let tick = tc.get_tick(0).unwrap(); + assert_eq!(tick.len(), 1); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 1); assert_eq!( - tc.get_tick(0).unwrap().get_attr("round"), - Some(&Attribute::Int(0)) + tick.get_gate_attr(0, "calibration"), + Some(&Attribute::String("a".into())) ); assert_eq!( - tc.get_tick(1).unwrap().get_attr("round"), - Some(&Attribute::Int(1)) + tick.get_gate_attr(0, "role"), + Some(&Attribute::String("drive".into())) ); } #[test] - fn test_tick_index() { + fn test_prep_metadata_applies_before_batching() { let mut tc = TickCircuit::new(); + tc.reserve_ticks(1); + tc.tick_at(0).pz(&[0]); + tc.tick_at(0) + .pz(&[1]) + .meta("calibration", Attribute::String("second".into())); - let t0 = tc.tick(); - assert_eq!(t0.index(), 0); - - let t1 = tc.tick(); - assert_eq!(t1.index(), 1); - - assert_eq!(tc.next_tick_index(), 2); + let tick = tc.get_tick(0).unwrap(); + assert_eq!(tick.len(), 2); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 2); + assert_eq!(tick.get_gate_attr(0, "calibration"), None); + assert_eq!( + tick.get_gate_attr(1, "calibration"), + Some(&Attribute::String("second".into())) + ); } #[test] - fn test_gates_chain_but_preps_and_meas_break() { + fn test_tick_construction_preserves_measurement_ids_when_batching() { let mut tc = TickCircuit::new(); + tc.reserve_ticks(1); - // Regular gates chain within a tick - tc.tick().h(&[0]).x(&[1]).y(&[2]).z(&[3]); + let refs0 = tc.tick_at(0).mz(&[0]); + let refs1 = tc.tick_at(0).mz(&[1]); + + let tick = tc.get_tick(0).unwrap(); + assert_eq!(tick.len(), 1); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 1); + assert_eq!(refs0[0].gate_idx, 0); + assert_eq!(refs1[0].gate_idx, 0); + assert_eq!(refs0[0].meas_id, MeasId(0)); + assert_eq!(refs1[0].meas_id, MeasId(1)); + assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)]); + } + + #[test] + fn test_measurement_batching_respects_gate_metadata() { + let mut same = TickCircuit::new(); + same.reserve_ticks(1); + let refs0 = same.tick_at(0).mz(&[0]); + same.get_tick_mut(0).unwrap().set_gate_attr( + refs0[0].gate_idx, + "basis", + Attribute::String("Z".into()), + ); + let refs1 = same.tick_at(0).mz(&[1]); + let tick = same.get_tick_mut(0).unwrap(); + tick.set_gate_attr(refs1[0].gate_idx, "basis", Attribute::String("Z".into())); + tick.merge_compatible_gate_at(refs1[0].gate_idx); + + let tick = same.get_tick(0).unwrap(); + assert_eq!(tick.len(), 1); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 1); + assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)]); + assert_eq!( + tick.get_gate_attr(0, "basis"), + Some(&Attribute::String("Z".into())) + ); + + let mut different = TickCircuit::new(); + different.reserve_ticks(1); + let refs0 = different.tick_at(0).mz(&[0]); + different.get_tick_mut(0).unwrap().set_gate_attr( + refs0[0].gate_idx, + "basis", + Attribute::String("Z".into()), + ); + let refs1 = different.tick_at(0).mz(&[1]); + let tick = different.get_tick_mut(0).unwrap(); + tick.set_gate_attr(refs1[0].gate_idx, "basis", Attribute::String("X".into())); + tick.merge_compatible_gate_at(refs1[0].gate_idx); + + let tick = different.get_tick(0).unwrap(); + assert_eq!(tick.len(), 2); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 2); + assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0)]); + assert_eq!(tick.gates()[1].meas_ids.as_slice(), &[MeasId(1)]); + assert_eq!( + tick.get_gate_attr(0, "basis"), + Some(&Attribute::String("Z".into())) + ); + assert_eq!( + tick.get_gate_attr(1, "basis"), + Some(&Attribute::String("X".into())) + ); + } + + #[test] + fn test_tick_construction_keeps_different_parameters_in_separate_batches() { + let mut tc = TickCircuit::new(); + tc.tick() + .rz(Angle64::from_turns(0.25), &[0]) + .rz(Angle64::from_turns(0.5), &[1]); + + let tick = tc.get_tick(0).unwrap(); + assert_eq!(tick.len(), 2); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 2); + } + + #[test] + fn test_parameterized_gate_batching_counts_and_round_trip() { + let mut tc1 = TickCircuit::new(); + tc1.tick() + .rz(Angle64::from_turns(0.25), &[0]) + .rz(Angle64::from_turns(0.25), &[1]) + .rz(Angle64::from_turns(0.5), &[2]); + + let tick = tc1.get_tick(0).unwrap(); + assert_eq!(tick.len(), 2); + assert_eq!(tick.gate_count(), 3); + assert_eq!(tick.gate_batch_count(), 2); + assert_eq!(tc1.gate_count(), 3); + assert_eq!(tc1.gate_batch_count(), 2); + + let dag = DagCircuit::from(&tc1); + assert_eq!(dag.gate_count(), 3); + assert_eq!(dag.gate_node_count(), 3); + assert_eq!(dag.gate_type_count(GateType::RZ), 3); + + let tc2 = TickCircuit::from(&dag); + let tick = tc2.get_tick(0).unwrap(); + assert_eq!(tc2.gate_count(), 3); + assert_eq!(tc2.gate_batch_count(), 2); + assert_eq!(tick.len(), 2); + assert_eq!(tick.gate_count(), 3); + assert_eq!(tick.gate_batch_count(), 2); + assert_eq!( + tick.gates()[0].qubits.as_slice(), + &[QubitId::from(0), QubitId::from(1)] + ); + assert_eq!( + tick.gates()[0].angles, + Gate::rz(Angle64::from_turns(0.25), &[0]).angles + ); + assert_eq!(tick.gates()[1].qubits.as_slice(), &[QubitId::from(2)]); + assert_eq!( + tick.gates()[1].angles, + Gate::rz(Angle64::from_turns(0.5), &[2]).angles + ); + } + + #[test] + fn test_meta_on_gates() { + let mut tc = TickCircuit::new(); + + tc.tick() + .h(&[0]) + .meta("duration", Attribute::Float(50.0)) + .meta("error_rate", Attribute::Float(0.001)) + .x(&[1]) + .meta("duration", Attribute::Float(50.0)); + + let tick = tc.get_tick(0).unwrap(); + assert_eq!( + tick.get_gate_attr(0, "duration"), + Some(&Attribute::Float(50.0)) + ); + assert_eq!( + tick.get_gate_attr(0, "error_rate"), + Some(&Attribute::Float(0.001)) + ); + assert_eq!( + tick.get_gate_attr(1, "duration"), + Some(&Attribute::Float(50.0)) + ); + } + + #[test] + fn test_tick_meta() { + let mut tc = TickCircuit::new(); + + // meta() before any gates = tick-level metadata + tc.tick().meta("round", Attribute::Int(0)).h(&[0]); + tc.tick().meta("round", Attribute::Int(1)).cx(&[(0, 1)]); + + assert_eq!( + tc.get_tick(0).unwrap().get_attr("round"), + Some(&Attribute::Int(0)) + ); + assert_eq!( + tc.get_tick(1).unwrap().get_attr("round"), + Some(&Attribute::Int(1)) + ); + } + + #[test] + fn test_tick_index() { + let mut tc = TickCircuit::new(); + + let t0 = tc.tick(); + assert_eq!(t0.index(), 0); + + let t1 = tc.tick(); + assert_eq!(t1.index(), 1); + + assert_eq!(tc.next_tick_index(), 2); + } + + #[test] + fn test_gates_chain_but_preps_and_meas_break() { + let mut tc = TickCircuit::new(); + + // Regular gates chain within a tick + tc.tick().h(&[0]).x(&[1]).y(&[2]).z(&[3]); tc.tick().cx(&[(0, 1)]).szz(&[(2, 3)]); // But preps and measurements break the chain @@ -2943,6 +3665,487 @@ mod tests { } } + #[test] + fn test_tick_dag_round_trip_preserves_counts_and_metadata_batches() { + let mut tc1 = TickCircuit::new(); + tc1.set_meta("name", Attribute::String("metadata-heavy".into())); + tc1.tick() + .meta("round", Attribute::Int(0)) + .h(&[0, 1]) + .meta("calibration", Attribute::String("h-cal".into())); + tc1.tick() + .meta("round", Attribute::Int(1)) + .cx(&[(0, 2), (1, 3)]) + .meta("calibration", Attribute::String("cx-cal".into())); + let ms = tc1.tick().mz(&[0, 1]); + + assert_eq!(tc1.num_ticks(), 3); + assert_eq!(tc1.gate_count(), 6); + assert_eq!(tc1.gate_batch_count(), 3); + assert_eq!(ms[0].meas_id, MeasId(0)); + assert_eq!(ms[1].meas_id, MeasId(1)); + + let dag = DagCircuit::from(&tc1); + assert_eq!(dag.gate_count(), 6); + assert_eq!(dag.gate_node_count(), 6); + assert_eq!(dag.gate_type_count(GateType::H), 2); + assert_eq!(dag.gate_type_count(GateType::CX), 2); + assert_eq!(dag.gate_type_count(GateType::MZ), 2); + + for (node, gate) in dag.iter_gates() { + match gate.gate_type { + GateType::H => assert_eq!( + dag.get_gate_attr(node, "calibration"), + Some(&Attribute::String("h-cal".into())) + ), + GateType::CX => assert_eq!( + dag.get_gate_attr(node, "calibration"), + Some(&Attribute::String("cx-cal".into())) + ), + _ => {} + } + } + + let tc2 = TickCircuit::from(&dag); + assert_eq!(tc2.num_ticks(), 3); + assert_eq!(tc2.gate_count(), 6); + assert_eq!(tc2.gate_batch_count(), 3); + assert_eq!( + tc2.get_meta("name"), + Some(&Attribute::String("metadata-heavy".into())) + ); + assert_eq!( + tc2.get_tick(0).unwrap().get_attr("round"), + Some(&Attribute::Int(0)) + ); + assert_eq!( + tc2.get_tick(1).unwrap().get_attr("round"), + Some(&Attribute::Int(1)) + ); + + let tick0 = tc2.get_tick(0).unwrap(); + assert_eq!(tick0.len(), 1); + assert_eq!(tick0.gate_count(), 2); + assert_eq!(tick0.gate_batch_count(), 1); + assert_eq!(tick0.gates()[0].gate_type, GateType::H); + assert_eq!( + tick0.get_gate_attr(0, "calibration"), + Some(&Attribute::String("h-cal".into())) + ); + + let tick1 = tc2.get_tick(1).unwrap(); + assert_eq!(tick1.len(), 1); + assert_eq!(tick1.gate_count(), 2); + assert_eq!(tick1.gate_batch_count(), 1); + assert_eq!(tick1.gates()[0].gate_type, GateType::CX); + assert_eq!( + tick1.get_gate_attr(0, "calibration"), + Some(&Attribute::String("cx-cal".into())) + ); + + let tick2 = tc2.get_tick(2).unwrap(); + assert_eq!(tick2.len(), 1); + assert_eq!(tick2.gate_count(), 2); + assert_eq!(tick2.gate_batch_count(), 1); + assert_eq!(tick2.gates()[0].gate_type, GateType::MZ); + assert_eq!( + tick2.gates()[0].meas_ids.as_slice(), + &[MeasId(0), MeasId(1)] + ); + } + + #[test] + fn test_dag_to_tick_preserves_distinct_metadata_batches() { + let mut dag = DagCircuit::new(); + let h0 = dag.add_gate(Gate::h(&[0])); + dag.set_gate_attr(h0, "calibration", Attribute::String("a".into())); + let h1 = dag.add_gate(Gate::h(&[1])); + dag.set_gate_attr(h1, "calibration", Attribute::String("b".into())); + let h2 = dag.add_gate(Gate::h(&[2])); + dag.set_gate_attr(h2, "calibration", Attribute::String("a".into())); + + let tc = TickCircuit::from(&dag); + assert_eq!(tc.gate_count(), 3); + assert_eq!(tc.gate_batch_count(), 2); + + let tick = tc.get_tick(0).unwrap(); + assert_eq!(tick.len(), 2); + assert_eq!(tick.gate_count(), 3); + assert_eq!(tick.gate_batch_count(), 2); + assert_eq!( + tick.get_gate_attr(0, "calibration"), + Some(&Attribute::String("a".into())) + ); + assert_eq!( + tick.get_gate_attr(1, "calibration"), + Some(&Attribute::String("b".into())) + ); + assert_eq!( + tick.gates()[0].qubits.as_slice(), + &[QubitId::from(0), QubitId::from(2)] + ); + assert_eq!(tick.gates()[1].qubits.as_slice(), &[QubitId::from(1)]); + } + + #[test] + fn test_batched_measurement_metadata_round_trip() { + let mut tc1 = TickCircuit::new(); + let ms = tc1.tick().mz(&[0, 1]); + tc1.get_tick_mut(0).unwrap().set_gate_attr( + ms[0].gate_idx, + "basis", + Attribute::String("Z".into()), + ); + + let dag = DagCircuit::from(&tc1); + assert_eq!(dag.gate_count(), 2); + assert_eq!(dag.gate_node_count(), 2); + for (node, gate) in dag.iter_gates() { + assert_eq!(gate.gate_type, GateType::MZ); + assert_eq!( + dag.get_gate_attr(node, "basis"), + Some(&Attribute::String("Z".into())) + ); + } + + let tc2 = TickCircuit::from(&dag); + assert_eq!(tc2.gate_count(), 2); + assert_eq!(tc2.gate_batch_count(), 1); + + let tick = tc2.get_tick(0).unwrap(); + assert_eq!(tick.len(), 1); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 1); + assert_eq!(tick.gates()[0].gate_type, GateType::MZ); + assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)]); + assert_eq!( + tick.get_gate_attr(0, "basis"), + Some(&Attribute::String("Z".into())) + ); + } + + #[test] + fn test_channel_gate_counts_as_single_operation_through_round_trip() { + let mut tc1 = TickCircuit::new(); + tc1.tick().channel( + pecos_core::channel::Depolarizing(0.1, 0) & pecos_core::channel::Dephasing(0.2, 1), + ); + + let tick = tc1.get_tick(0).unwrap(); + assert_eq!(tick.len(), 1); + assert_eq!(tick.gate_count(), 1); + assert_eq!(tick.gate_batch_count(), 1); + assert_eq!(tc1.gate_count(), 1); + assert_eq!(tc1.gate_batch_count(), 1); + assert_eq!( + tick.gates()[0].qubits.as_slice(), + &[QubitId::from(0), QubitId::from(1)] + ); + + let dag = DagCircuit::from(&tc1); + assert_eq!(dag.gate_count(), 1); + assert_eq!(dag.gate_node_count(), 1); + let (_, gate) = dag.iter_gates().next().unwrap(); + assert!(gate.is_channel()); + assert_eq!( + gate.qubits.as_slice(), + &[QubitId::from(0), QubitId::from(1)] + ); + + let tc2 = TickCircuit::from(&dag); + assert_eq!(tc2.gate_count(), 1); + assert_eq!(tc2.gate_batch_count(), 1); + let gate = &tc2.get_tick(0).unwrap().gates()[0]; + assert!(gate.is_channel()); + assert_eq!( + gate.qubits.as_slice(), + &[QubitId::from(0), QubitId::from(1)] + ); + } + + #[test] + fn test_batched_measurement_annotation_records_round_trip() { + let mut tc1 = TickCircuit::new(); + let ms = tc1.tick().mz(&[0, 1]); + tc1.detector_labeled("det01", &ms); + tc1.observable_labeled("obs1", &[ms[1]]); + + let dag = DagCircuit::from(&tc1); + let tc2 = TickCircuit::from(&dag); + + assert_eq!(tc2.num_measurements(), 2); + assert_eq!(tc2.annotations().len(), 2); + match &tc2.annotations()[0].kind { + AnnotationKind::Detector { + measurement_nodes, .. + } => assert_eq!(measurement_nodes.as_slice(), &[0, 1]), + other => panic!("expected detector annotation, got {other:?}"), + } + match &tc2.annotations()[1].kind { + AnnotationKind::Observable { measurement_nodes } => { + assert_eq!(measurement_nodes.as_slice(), &[1]); + } + other => panic!("expected observable annotation, got {other:?}"), + } + + let tick = tc2.get_tick(0).unwrap(); + assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)]); + } + + #[test] + fn test_dag_batched_measurement_node_annotation_expands_to_tick_records() { + let mut dag = DagCircuit::new(); + let node = dag.add_gate(Gate::mz(&[0, 1])); + dag.detector_labeled("batched-detector", &[node]); + + let tc = TickCircuit::from(&dag); + assert_eq!(tc.num_measurements(), 2); + assert_eq!(tc.annotations().len(), 1); + match &tc.annotations()[0].kind { + AnnotationKind::Detector { + measurement_nodes, .. + } => assert_eq!(measurement_nodes.as_slice(), &[0, 1]), + other => panic!("expected detector annotation, got {other:?}"), + } + + let tick = tc.get_tick(0).unwrap(); + assert_eq!(tick.len(), 1); + assert_eq!(tick.gates()[0].gate_type, GateType::MZ); + assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)]); + } + + #[test] + fn test_dag_to_tick_preserves_existing_measurement_ids_and_advances_counter() { + let mut dag = DagCircuit::new(); + let mut gate = Gate::mz(&[0]); + gate.meas_ids.push(MeasId(5)); + let node = dag.add_gate(gate); + dag.observable_labeled("obs5", &[node]); + + let mut tc = TickCircuit::from(&dag); + assert_eq!(tc.num_measurements(), 6); + let tick = tc.get_tick(0).unwrap(); + assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(5)]); + match &tc.annotations()[0].kind { + AnnotationKind::Observable { measurement_nodes } => { + assert_eq!(measurement_nodes.as_slice(), &[5]); + } + other => panic!("expected observable annotation, got {other:?}"), + } + + let next = tc.tick().mz(&[1]); + assert_eq!(next[0].record_idx, 6); + assert_eq!(next[0].meas_id, MeasId(6)); + assert_eq!(tc.num_measurements(), 7); + } + + #[test] + #[should_panic(expected = "annotation references non-measurement DAG node")] + fn test_dag_to_tick_rejects_annotation_referencing_non_measurement_node() { + let mut dag = DagCircuit::new(); + let h = dag.add_gate(Gate::h(&[0])); + dag.detector_labeled("not-a-measurement", &[h]); + + let _ = TickCircuit::from(&dag); + } + + #[test] + fn test_detector_observable_and_tracked_operator_remain_distinct_after_round_trip() { + use pecos_core::pauli::{X, Z}; + + let mut tc1 = TickCircuit::new(); + tc1.tick().pz(&[0, 1, 2]); + let ms = tc1.tick().mz(&[0, 1]); + tc1.detector_labeled("detector", &[ms[0]]); + tc1.observable_labeled("observable", &[ms[1]]); + tc1.tracked_operator_labeled("tracked", X(0) & Z(2)); + + let tc2 = TickCircuit::from(&DagCircuit::from(&tc1)); + assert_eq!(tc2.annotations().len(), 3); + + assert_eq!(tc2.annotations()[0].label.as_deref(), Some("detector")); + match &tc2.annotations()[0].kind { + AnnotationKind::Detector { + measurement_nodes, .. + } => assert_eq!(measurement_nodes.as_slice(), &[0]), + other => panic!("expected detector annotation, got {other:?}"), + } + + assert_eq!(tc2.annotations()[1].label.as_deref(), Some("observable")); + match &tc2.annotations()[1].kind { + AnnotationKind::Observable { measurement_nodes } => { + assert_eq!(measurement_nodes.as_slice(), &[1]); + } + other => panic!("expected observable annotation, got {other:?}"), + } + + assert_eq!(tc2.annotations()[2].label.as_deref(), Some("tracked")); + assert!(matches!( + tc2.annotations()[2].kind, + AnnotationKind::TrackedOperator + )); + assert_eq!(tc2.annotations()[2].pauli, X(0) & Z(2)); + } + + #[test] + fn test_small_pseudorandom_tick_dag_round_trip_invariants() { + fn assert_no_tick_overlaps(circuit: &TickCircuit) { + for (tick_idx, tick) in circuit.ticks().iter().enumerate() { + let mut active = BTreeSet::new(); + for gate in tick.gates() { + gate.validate() + .unwrap_or_else(|err| panic!("invalid gate in tick {tick_idx}: {err}")); + for &qubit in &gate.qubits { + assert!( + active.insert(qubit), + "qubit {qubit:?} appears more than once in tick {tick_idx}" + ); + } + } + } + } + + fn measurement_ids(circuit: &TickCircuit) -> Vec { + circuit + .iter_gates() + .flat_map(|gate| gate.meas_ids.iter().copied()) + .collect() + } + + let mut state = 0x5eed_u64; + for case_idx in 0..16 { + state = state + .wrapping_mul(6_364_136_223_846_793_005) + .wrapping_add(1); + let base = ((state >> 32) as usize % 4) * 10; + + let mut tc1 = TickCircuit::new(); + tc1.tick() + .meta("case", Attribute::Int(case_idx)) + .h(&[base, base + 1]) + .meta("role", Attribute::String("prepare".into())); + + if state & 1 == 0 { + tc1.tick() + .cx(&[(base, base + 2), (base + 1, base + 3)]) + .meta("role", Attribute::String("entangle".into())); + } else { + tc1.tick() + .rz(Angle64::from_turns(0.25), &[base]) + .rz(Angle64::from_turns(0.25), &[base + 1]) + .rz(Angle64::from_turns(0.5), &[base + 2]); + } + + let ms = tc1.tick().mz(&[base, base + 1]); + if case_idx % 2 == 0 { + tc1.detector_labeled("det", &ms); + } else { + tc1.observable_labeled("obs", &ms); + } + + let tc2 = TickCircuit::from(&DagCircuit::from(&tc1)); + assert_eq!(tc2.gate_count(), tc1.gate_count()); + assert_eq!(tc2.num_measurements(), tc1.num_measurements()); + assert_eq!(tc2.gate_counts_by_type(), tc1.gate_counts_by_type()); + assert_eq!(measurement_ids(&tc2), measurement_ids(&tc1)); + assert_eq!(tc2.annotations().len(), tc1.annotations().len()); + assert_no_tick_overlaps(&tc2); + } + } + + #[test] + fn test_pseudorandom_round_trip_preserves_measurement_annotation_details() { + use pecos_core::pauli::{X, Y, Z}; + + fn annotation_by_label<'a>(circuit: &'a TickCircuit, label: &str) -> &'a PauliAnnotation { + circuit + .annotations() + .iter() + .find(|ann| ann.label.as_deref() == Some(label)) + .unwrap_or_else(|| panic!("missing annotation {label}")) + } + + let mut state = 0xaced_u64; + for case_idx in 0..12 { + state = state + .wrapping_mul(2_862_933_555_777_941_757) + .wrapping_add(3_037_000_493); + let base = 20 * case_idx; + + let mut tc1 = TickCircuit::new(); + tc1.tick().h(&[base, base + 1]).cx(&[(base + 2, base + 3)]); + if state & 1 == 0 { + tc1.tick().cx(&[(base, base + 2), (base + 1, base + 3)]); + } else { + tc1.tick() + .rz(Angle64::from_turns(0.25), &[base]) + .rz(Angle64::from_turns(0.25), &[base + 1]); + } + + let measurements = tc1.tick().mz(&[base, base + 1, base + 2]); + let detector_records = if state & 2 == 0 { + vec![measurements[0], measurements[2]] + } else { + vec![measurements[1]] + }; + let observable_records = if state & 4 == 0 { + vec![measurements[1]] + } else { + vec![measurements[0], measurements[2]] + }; + let tracked = if state & 8 == 0 { + X(base) & Z(base + 3) + } else { + Y(base + 3) + }; + + tc1.detector_labeled(&format!("det-{case_idx}"), &detector_records); + tc1.observable_labeled(&format!("obs-{case_idx}"), &observable_records); + tc1.tracked_operator_labeled(&format!("track-{case_idx}"), tracked.clone()); + + let tc2 = TickCircuit::from(&DagCircuit::from(&tc1)); + assert_eq!(tc2.gate_count(), tc1.gate_count(), "case {case_idx}"); + assert_eq!( + tc2.num_measurements(), + tc1.num_measurements(), + "case {case_idx}" + ); + assert_eq!(tc2.annotations().len(), 3, "case {case_idx}"); + + let det = annotation_by_label(&tc2, &format!("det-{case_idx}")); + match &det.kind { + AnnotationKind::Detector { + measurement_nodes, .. + } => assert_eq!( + measurement_nodes, + &detector_records + .iter() + .map(|m| m.record_idx) + .collect::>(), + "case {case_idx}" + ), + other => panic!("expected detector annotation, got {other:?}"), + } + + let obs = annotation_by_label(&tc2, &format!("obs-{case_idx}")); + match &obs.kind { + AnnotationKind::Observable { measurement_nodes } => assert_eq!( + measurement_nodes, + &observable_records + .iter() + .map(|m| m.record_idx) + .collect::>(), + "case {case_idx}" + ), + other => panic!("expected observable annotation, got {other:?}"), + } + + let track = annotation_by_label(&tc2, &format!("track-{case_idx}")); + assert!(matches!(track.kind, AnnotationKind::TrackedOperator)); + assert_eq!(track.pauli, tracked, "case {case_idx}"); + } + } + #[test] fn test_tick_attrs_preserved_in_conversion() { let mut tc1 = TickCircuit::new(); @@ -3057,6 +4260,26 @@ mod tests { assert!(handle.try_add_gate(Gate::x(&[1])).is_ok()); } + #[test] + fn test_batched_two_qubit_gate_accepts_disjoint_pairs_and_rejects_overlap() { + let mut tick = Tick::new(); + assert!(tick.try_add_gate(Gate::cx(&[(0, 1), (2, 3)])).is_ok()); + assert_eq!(tick.len(), 1); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 1); + + let err = Tick::new() + .try_add_gate(Gate::cx(&[(0, 1), (1, 2)])) + .unwrap_err(); + match err { + TickGateError::InvalidGate { message, .. } => { + assert!(message.contains("requires distinct qubits")); + assert!(message.contains('1')); + } + TickGateError::QubitConflict(_) => panic!("overlap within one gate command is invalid"), + } + } + #[test] fn test_try_add_gate_conflict() { let mut tc = TickCircuit::new(); @@ -3067,11 +4290,12 @@ mod tests { let result = handle.try_add_gate(Gate::x(&[0])); match result { - Err(err) => { + Err(TickGateError::QubitConflict(err)) => { assert_eq!(err.conflicting_qubits, vec![QubitId::from(0)]); assert_eq!(err.tick_idx, Some(0)); } Ok(_) => panic!("Expected conflict error"), + Err(err) => panic!("Expected conflict error, got {err}"), } } @@ -3099,6 +4323,34 @@ mod tests { assert!(result.is_err()); } + #[test] + fn test_try_add_gate_rejects_invalid_gate_payload_before_storage() { + let mut tc = TickCircuit::new(); + let mut handle = tc.tick(); + let invalid = Gate::cx(&[(0, 0)]); + + let result = handle.try_add_gate(invalid); + + match result { + Err(TickGateError::InvalidGate { + message, tick_idx, .. + }) => { + assert_eq!(tick_idx, Some(0)); + assert!(message.contains("requires distinct qubits")); + } + Ok(_) => panic!("Expected invalid-gate error"), + Err(err) => panic!("Expected invalid-gate error, got {err}"), + } + assert!(tc.get_tick(0).unwrap().is_empty()); + } + + #[test] + #[should_panic(expected = "Invalid gate in tick 0")] + fn test_tick_handle_panics_on_invalid_gate_payload() { + let mut tc = TickCircuit::new(); + tc.tick().cx(&[(0, 0)]); + } + #[test] fn test_metas_on_gates() { let mut tc = TickCircuit::new(); @@ -3188,9 +4440,9 @@ mod tests { #[test] fn test_iteration_helpers() { let mut tc = TickCircuit::new(); - tc.tick().h(&[0, 1]); - tc.tick().cx(&[(0, 1)]); - tc.tick().mz(&[0, 1]); + tc.tick().h(&[0, 1, 2, 3]); + tc.tick().cx(&[(0, 1), (2, 3)]); + tc.tick().mz(&[0, 1, 2, 3]); // Test iter_gates let gates: Vec<_> = tc.iter_gates().collect(); @@ -3212,15 +4464,17 @@ mod tests { // Test all_qubits let qubits = tc.all_qubits(); - assert_eq!(qubits.len(), 2); + assert_eq!(qubits.len(), 4); assert!(qubits.contains(&QubitId::from(0))); assert!(qubits.contains(&QubitId::from(1))); + assert!(qubits.contains(&QubitId::from(2))); + assert!(qubits.contains(&QubitId::from(3))); // Test gate_counts_by_type let counts = tc.gate_counts_by_type(); - assert_eq!(counts.get(&GateType::H), Some(&1)); - assert_eq!(counts.get(&GateType::CX), Some(&1)); - assert_eq!(counts.get(&GateType::MZ), Some(&1)); + assert_eq!(counts.get(&GateType::H), Some(&4)); + assert_eq!(counts.get(&GateType::CX), Some(&2)); + assert_eq!(counts.get(&GateType::MZ), Some(&4)); } #[test] @@ -3696,7 +4950,8 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().pz(&[0, 1, 2]); - tc.tick().cx(&[(0, 2), (1, 2)]); + tc.tick().cx(&[(0, 2)]); + tc.tick().cx(&[(1, 2)]); let ms = tc.tick().mz(&[2]); assert_eq!(ms.len(), 1); @@ -3718,7 +4973,8 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().pz(&[0, 1, 2]); - tc.tick().cx(&[(0, 2), (1, 2)]); + tc.tick().cx(&[(0, 2)]); + tc.tick().cx(&[(1, 2)]); let ms = tc.tick().mz(&[2]); tc.detector_labeled("det0", &ms); tc.observable_labeled("obs0", &ms); @@ -3873,6 +5129,104 @@ mod tests { ); } + #[test] + fn test_with_noise_on_batched_source_gate_emits_per_qubit_channels() { + use std::cell::{Cell, RefCell}; + + let mut tc = TickCircuit::new(); + tc.tick().h(&[0, 1]); + + let calls = Cell::new(0); + let seen_qubits = RefCell::new(Vec::new()); + let noisy = tc.with_noise(&|gate: &Gate| { + calls.set(calls.get() + 1); + seen_qubits.borrow_mut().push(gate.qubits.clone()); + gate.qubits + .iter() + .map(|qubit| pecos_core::channel::Depolarizing(0.01, qubit.index())) + .collect() + }); + + assert_eq!(calls.get(), 1); + assert_eq!( + seen_qubits.borrow()[0].as_slice(), + &[QubitId::from(0), QubitId::from(1)] + ); + assert_eq!(noisy.num_ticks(), 2); + assert_eq!(noisy.get_tick(0).unwrap().gate_count(), 2); + + let noise_tick = noisy.get_tick(1).unwrap(); + assert_eq!(noise_tick.len(), 2); + assert_eq!(noise_tick.gate_count(), 2); + assert!(noise_tick.gates().iter().all(Gate::is_channel)); + assert_eq!(noise_tick.gates()[0].qubits.as_slice(), &[QubitId::from(0)]); + assert_eq!(noise_tick.gates()[1].qubits.as_slice(), &[QubitId::from(1)]); + } + + #[test] + fn test_with_noise_on_batched_measurement_places_channels_after_measurement_tick() { + use std::cell::{Cell, RefCell}; + + let mut tc = TickCircuit::new(); + tc.tick().mz(&[0, 1]); + + let calls = Cell::new(0); + let seen_measurement_ids = RefCell::new(Vec::new()); + let noisy = tc.with_noise(&|gate: &Gate| { + assert_eq!(gate.gate_type, GateType::MZ); + calls.set(calls.get() + 1); + seen_measurement_ids + .borrow_mut() + .extend(gate.meas_ids.iter().copied()); + gate.qubits + .iter() + .map(|qubit| pecos_core::channel::Dephasing(0.02, qubit.index())) + .collect() + }); + + assert_eq!(calls.get(), 1); + assert_eq!( + seen_measurement_ids.borrow().as_slice(), + &[MeasId(0), MeasId(1)] + ); + assert_eq!(noisy.num_ticks(), 2); + + let meas_tick = noisy.get_tick(0).unwrap(); + assert_eq!(meas_tick.gates()[0].gate_type, GateType::MZ); + assert_eq!( + meas_tick.gates()[0].meas_ids.as_slice(), + &[MeasId(0), MeasId(1)] + ); + + let noise_tick = noisy.get_tick(1).unwrap(); + assert_eq!(noise_tick.len(), 2); + assert!(noise_tick.gates().iter().all(Gate::is_channel)); + assert_eq!(noise_tick.gates()[0].qubits.as_slice(), &[QubitId::from(0)]); + assert_eq!(noise_tick.gates()[1].qubits.as_slice(), &[QubitId::from(1)]); + } + + #[test] + fn test_with_noise_empty_channels_preserves_tick_structure() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[0]).x(&[1]); + tc.tick().cx(&[(0, 1)]); + tc.tick().mz(&[0, 1]); + + let noisy = tc.with_noise(&|_: &Gate| Vec::new()); + + assert_eq!(noisy.num_ticks(), tc.num_ticks()); + for tick_idx in 0..tc.num_ticks() { + let original = tc.get_tick(tick_idx).unwrap(); + let copied = noisy.get_tick(tick_idx).unwrap(); + assert_eq!(copied.gates().len(), original.gates().len()); + for (copied_gate, original_gate) in copied.gates().iter().zip(original.gates()) { + assert_eq!(copied_gate.gate_type, original_gate.gate_type); + assert_eq!(copied_gate.qubits, original_gate.qubits); + assert!(!copied_gate.is_channel()); + } + } + } + #[test] fn test_with_noise_splits_conflicting_channel_ticks() { let mut tc = TickCircuit::new(); diff --git a/crates/pecos-quantum/src/tick_circuit_soa.rs b/crates/pecos-quantum/src/tick_circuit_soa.rs index db9b5e3f0..da2b5df5f 100644 --- a/crates/pecos-quantum/src/tick_circuit_soa.rs +++ b/crates/pecos-quantum/src/tick_circuit_soa.rs @@ -5,7 +5,7 @@ //! //! # Design Goals //! -//! 1. **Batched gate application**: Gates grouped by type within each tick for batch execution +//! 1. **Batched gate execution**: Gates grouped by type within each tick for batch execution //! 2. **Cache-friendly memory layout**: Qubits for same-type gates stored contiguously //! 3. **O(1) lookups**: Pre-computed indexes for qubit-to-gate and tick-to-gate queries //! 4. **Efficient simulation**: Direct batch calls to simulator without per-gate dispatch @@ -85,7 +85,7 @@ use crate::Attribute; use pecos_core::gate_type::GateType; -use pecos_core::{Angle64, QubitId}; +use pecos_core::{Angle64, Gate, QubitId}; use smallvec::SmallVec; use std::collections::BTreeMap; @@ -138,15 +138,11 @@ impl GateBatch { &self.angles } - /// Returns the number of gate instances in this batch. + /// Returns the number of gates in this batch. #[inline] #[must_use] pub fn gate_count(&self) -> usize { - let arity = self.gate_type.quantum_arity(); - self.qubits - .len() - .checked_div(arity) - .unwrap_or(self.qubits.len()) + self.gate_type.num_gates(self.qubits.len()) } /// Returns true if the batch is empty. @@ -436,6 +432,30 @@ impl GateStorage { self.occupied.iter().filter(|&&o| o).count() } + /// Returns the number of active gates. + #[must_use] + pub fn active_gate_count(&self) -> usize { + (0..self.types.len()) + .filter(|&idx| self.occupied[idx]) + .map(|idx| { + let (qubit_start, qubit_end) = self.qubit_spans[idx]; + self.types[idx].num_gates((qubit_end as usize).saturating_sub(qubit_start as usize)) + }) + .sum() + } + + fn gate_from_index(&self, idx: usize) -> Gate { + let (qubit_start, qubit_end) = self.qubit_spans[idx]; + let (angle_start, angle_end) = self.angle_spans[idx]; + let (param_start, param_end) = self.param_spans[idx]; + Gate::new( + self.types[idx], + self.angles[angle_start as usize..angle_end as usize].to_vec(), + self.params[param_start as usize..param_end as usize].to_vec(), + self.qubits[qubit_start as usize..qubit_end as usize].to_vec(), + ) + } + /// Adds a gate and returns its ID. pub fn add_gate( &mut self, @@ -860,6 +880,13 @@ impl MetadataStorage { } } +fn normalized_attrs( + gate_attrs: &BTreeMap>, + gate_id: GateId, +) -> Option<&BTreeMap> { + gate_attrs.get(&gate_id).filter(|attrs| !attrs.is_empty()) +} + // ============================================================================ // TickCircuitSoA // ============================================================================ @@ -907,7 +934,46 @@ impl TickCircuitSoA { #[inline] #[must_use] pub fn gate_count(&self) -> usize { - self.storage.active_count() + self.storage.active_gate_count() + } + + /// Returns the number of compatible gate batches across all ticks. + /// + /// This is a representation-level batch count: gates share a batch only + /// when they are identical except for disjoint qubits and have equivalent + /// per-gate metadata. + #[must_use] + pub fn gate_batch_count(&self) -> usize { + let mut total = 0; + + for tick in 0..self.indexes.num_ticks { + let mut representative_indices: Vec = Vec::new(); + + 'gate: for &gate_idx in self.indexes.gates_in_tick(tick) { + if !self.storage.is_occupied(gate_idx as usize) { + continue; + } + let gate = self.storage.gate_from_index(gate_idx as usize); + let gate_id = GateId::new(gate_idx, self.storage.generations[gate_idx as usize]); + + for &rep_idx in &representative_indices { + let rep_gate = self.storage.gate_from_index(rep_idx as usize); + let rep_id = GateId::new(rep_idx, self.storage.generations[rep_idx as usize]); + if normalized_attrs(&self.metadata.gate_attrs, rep_id) + == normalized_attrs(&self.metadata.gate_attrs, gate_id) + && rep_gate.can_batch_with(&gate) + { + continue 'gate; + } + } + + representative_indices.push(gate_idx); + } + + total += representative_indices.len(); + } + + total } /// Returns the maximum qubit index. @@ -1246,8 +1312,9 @@ impl From<&crate::TickCircuit> for TickCircuitSoA { builder .storage .add_gate(gate.gate_type, tick_num, &qubits, &angles, ¶ms); - builder.indexes.register_gate(gate_id, &qubits); - builder.indexes.num_ticks = builder.indexes.num_ticks.max(tick_num as usize + 1); + builder + .indexes + .register_gate_raw(gate_id.index, tick_num, &qubits); // Copy gate attributes for (key, value) in tick_data.gate_attrs(gate_idx) { @@ -1289,7 +1356,7 @@ mod tests { let circuit = builder.build(); assert_eq!(circuit.num_ticks(), 3); - assert_eq!(circuit.gate_count(), 4); // pz, h, cx, mz + assert_eq!(circuit.gate_count(), 6); // 2 PZ, 1 H, 1 CX, 2 MZ } #[test] @@ -1421,6 +1488,8 @@ mod tests { // Check tick count assert_eq!(circuit.num_ticks_batched(), 4); + assert_eq!(circuit.gate_count(), 14); + assert_eq!(circuit.gate_batch_count(), 5); // Check tick 0: preps batched together let tick0 = circuit.tick_batched(0).unwrap(); @@ -1452,6 +1521,33 @@ mod tests { assert_eq!(mz_batch.gate_count(), 4); } + #[test] + fn test_gate_batch_count_respects_metadata() { + let mut same = crate::TickCircuit::new(); + { + let mut tick = same.tick(); + tick.h(&[0]) + .meta("calibration", Attribute::String("a".into())); + tick.h(&[1]) + .meta("calibration", Attribute::String("a".into())); + } + let same_soa = TickCircuitSoA::from(&same); + assert_eq!(same_soa.gate_count(), 2); + assert_eq!(same_soa.gate_batch_count(), 1); + + let mut different = crate::TickCircuit::new(); + { + let mut tick = different.tick(); + tick.h(&[0]) + .meta("calibration", Attribute::String("a".into())); + tick.h(&[1]) + .meta("calibration", Attribute::String("b".into())); + } + let different_soa = TickCircuitSoA::from(&different); + assert_eq!(different_soa.gate_count(), 2); + assert_eq!(different_soa.gate_batch_count(), 2); + } + #[test] fn test_iter_ticks_batched() { let mut builder = TickCircuitSoA::builder(); diff --git a/crates/pecos-quantum/src/unitary_matrix.rs b/crates/pecos-quantum/src/unitary_matrix.rs index f67310ebd..07d8905f8 100644 --- a/crates/pecos-quantum/src/unitary_matrix.rs +++ b/crates/pecos-quantum/src/unitary_matrix.rs @@ -1265,6 +1265,24 @@ pub fn to_matrix_with_size(op: &UnitaryRep, num_qubits: usize) -> UnitaryMatrix UnitaryMatrix(to_matrix_with_size_impl(op, num_qubits)) } +fn assert_tensor_parts_have_disjoint_support(parts: &[UnitaryRep]) { + let mut used = std::collections::BTreeSet::new(); + for part in parts { + let mut overlap = Vec::new(); + for q in part.qubits() { + if used.contains(&q) { + overlap.push(q); + } else { + used.insert(q); + } + } + assert!( + overlap.is_empty(), + "tensor product requires disjoint unitary support; overlapping qubits: {overlap:?}" + ); + } +} + /// Internal implementation that returns raw `DMatrix` for recursive use. fn to_matrix_with_size_impl(op: &UnitaryRep, num_qubits: usize) -> DMatrix { let dim = 1 << num_qubits; // 2^num_qubits @@ -1306,6 +1324,8 @@ fn to_matrix_with_size_impl(op: &UnitaryRep, num_qubits: usize) -> DMatrix { + assert_tensor_parts_have_disjoint_support(parts); + // Start with identity, combine each part let mut result = DMatrix::identity(dim, dim); for part in parts { @@ -2140,6 +2160,40 @@ mod tests { assert!(matrices_equiv_up_to_phase(&mat, &expected, 1e-10)); } + fn assert_tensor_matrix_matches_embedded_product( + lhs: &pecos_core::unitary_rep::UnitaryRep, + rhs: &pecos_core::unitary_rep::UnitaryRep, + num_qubits: usize, + ) { + let tensor = lhs.clone() & rhs.clone(); + let tensor_matrix = to_matrix_with_size(&tensor, num_qubits); + let lhs_matrix = to_matrix_with_size(lhs, num_qubits); + let rhs_matrix = to_matrix_with_size(rhs, num_qubits); + let expected = &lhs_matrix * &rhs_matrix; + + assert!( + matrices_equiv_up_to_phase(&tensor_matrix, &expected, 1e-10), + "{tensor:?} matrix did not match embedded product" + ); + } + + #[test] + fn test_disjoint_tensor_matrix_semantics_across_operator_levels() { + assert_tensor_matrix_matches_embedded_product(&X(0), &Z(1), 2); + assert_tensor_matrix_matches_embedded_product(&H(0), &SZ(1), 2); + assert_tensor_matrix_matches_embedded_product(&H(0), &T(1), 2); + assert_tensor_matrix_matches_embedded_product(&CX(0, 2), &T(1), 3); + assert_tensor_matrix_matches_embedded_product(&H(3), &CX(0, 2), 4); + } + + #[test] + #[should_panic(expected = "tensor product requires disjoint unitary support")] + fn test_to_matrix_rejects_invalid_overlapping_tensor_node() { + let invalid = pecos_core::unitary_rep::UnitaryRep::Tensor(vec![X(0), Z(0)]); + + let _ = to_matrix(&invalid); + } + #[test] fn test_composition() { // H * X = XH (matrix multiplication order) diff --git a/crates/pecos-simulators/src/bitmask_pauli_prop.rs b/crates/pecos-simulators/src/bitmask_pauli_prop.rs index c09db915a..563eff419 100644 --- a/crates/pecos-simulators/src/bitmask_pauli_prop.rs +++ b/crates/pecos-simulators/src/bitmask_pauli_prop.rs @@ -467,6 +467,38 @@ mod tests { } } + fn assert_matches_sparse_2q_at_pair( + name: &str, + pair: (QubitId, QubitId), + num_qubits: usize, + mut apply_sparse: F, + mut apply_bitmask: G, + ) where + F: FnMut(&mut PauliProp, &[(QubitId, QubitId)]), + G: FnMut(&mut BitmaskPauliProp, &[(QubitId, QubitId)]), + { + let labels = ['I', 'X', 'Y', 'Z']; + let pairs = [pair]; + for lhs in labels { + for rhs in labels { + let mut input = vec!['I'; num_qubits]; + input[pair.0.0] = lhs; + input[pair.1.0] = rhs; + let input = input.into_iter().collect::(); + + let mut sparse = sparse_prop_from_dense(&input); + let mut bitmask = bitmask_prop_from_dense(&input); + apply_sparse(&mut sparse, &pairs); + apply_bitmask(&mut bitmask, &pairs); + assert_eq!( + bitmask.dense_string(), + sparse.dense_string(), + "{name}: pair {pair:?}, input {input}" + ); + } + } + } + #[test] fn single_qubit_cliffords_match_sparse_pauli_prop() { assert_matches_sparse_1q( @@ -644,6 +676,233 @@ mod tests { p.swap(qs); }, ); + assert_matches_sparse_2q( + "ISWAP", + |p, qs| { + p.iswap(qs); + }, + |p, qs| { + p.iswap(qs); + }, + ); + assert_matches_sparse_2q( + "ISWAPdg", + |p, qs| { + p.iswapdg(qs); + }, + |p, qs| { + p.iswapdg(qs); + }, + ); + } + + #[test] + fn two_qubit_cliffords_match_sparse_pauli_prop_across_word_boundaries() { + for pair in [ + (QubitId(63), QubitId(64)), + (QubitId(64), QubitId(63)), + (QubitId(64), QubitId(65)), + ] { + assert_matches_sparse_2q_at_pair( + "CX", + pair, + 66, + |p, qs| { + p.cx(qs); + }, + |p, qs| { + p.cx(qs); + }, + ); + assert_matches_sparse_2q_at_pair( + "CY", + pair, + 66, + |p, qs| { + p.cy(qs); + }, + |p, qs| { + p.cy(qs); + }, + ); + assert_matches_sparse_2q_at_pair( + "CZ", + pair, + 66, + |p, qs| { + p.cz(qs); + }, + |p, qs| { + p.cz(qs); + }, + ); + assert_matches_sparse_2q_at_pair( + "SXX", + pair, + 66, + |p, qs| { + p.sxx(qs); + }, + |p, qs| { + p.sxx(qs); + }, + ); + assert_matches_sparse_2q_at_pair( + "SXXdg", + pair, + 66, + |p, qs| { + p.sxxdg(qs); + }, + |p, qs| { + p.sxxdg(qs); + }, + ); + assert_matches_sparse_2q_at_pair( + "SYY", + pair, + 66, + |p, qs| { + p.syy(qs); + }, + |p, qs| { + p.syy(qs); + }, + ); + assert_matches_sparse_2q_at_pair( + "SYYdg", + pair, + 66, + |p, qs| { + p.syydg(qs); + }, + |p, qs| { + p.syydg(qs); + }, + ); + assert_matches_sparse_2q_at_pair( + "SZZ", + pair, + 66, + |p, qs| { + p.szz(qs); + }, + |p, qs| { + p.szz(qs); + }, + ); + assert_matches_sparse_2q_at_pair( + "SZZdg", + pair, + 66, + |p, qs| { + p.szzdg(qs); + }, + |p, qs| { + p.szzdg(qs); + }, + ); + assert_matches_sparse_2q_at_pair( + "SWAP", + pair, + 66, + |p, qs| { + p.swap(qs); + }, + |p, qs| { + p.swap(qs); + }, + ); + assert_matches_sparse_2q_at_pair( + "ISWAP", + pair, + 66, + |p, qs| { + p.iswap(qs); + }, + |p, qs| { + p.iswap(qs); + }, + ); + assert_matches_sparse_2q_at_pair( + "ISWAPdg", + pair, + 66, + |p, qs| { + p.iswapdg(qs); + }, + |p, qs| { + p.iswapdg(qs); + }, + ); + } + } + + #[test] + fn word_boundary_propagation_matches_sparse_pauli_prop() { + let qubits = [63, 64, 65]; + let qids = qubits.map(QubitId); + let mut sparse = PauliProp::with_sign_tracking(66); + let mut bitmask = BitmaskPauliProp::with_num_qubits(66); + + sparse.track_z(&qubits); + bitmask.track_z(&qubits); + sparse.h(&qids); + bitmask.h(&qids); + + assert_eq!(bitmask.dense_string(), sparse.dense_string()); + + let sparse_meas = sparse.mz(&qids); + let bitmask_meas = bitmask.mz(&qids); + assert_eq!( + bitmask_meas.iter().map(|m| m.outcome).collect::>(), + sparse_meas.iter().map(|m| m.outcome).collect::>() + ); + assert_eq!( + bitmask_meas + .iter() + .map(|m| m.is_deterministic) + .collect::>(), + sparse_meas + .iter() + .map(|m| m.is_deterministic) + .collect::>() + ); + } + + #[test] + fn sequential_gate_composition_matches_sparse_pauli_prop() { + let sequence = |sparse: &mut PauliProp, bitmask: &mut BitmaskPauliProp| { + sparse + .h(&[QubitId(0)]) + .sz(&[QubitId(1)]) + .cx(&[(QubitId(0), QubitId(1))]) + .sxx(&[(QubitId(1), QubitId(2))]) + .iswap(&[(QubitId(0), QubitId(2))]) + .sydg(&[QubitId(2)]) + .cz(&[(QubitId(2), QubitId(1))]) + .swap(&[(QubitId(0), QubitId(1))]); + bitmask + .h(&[QubitId(0)]) + .sz(&[QubitId(1)]) + .cx(&[(QubitId(0), QubitId(1))]) + .sxx(&[(QubitId(1), QubitId(2))]) + .iswap(&[(QubitId(0), QubitId(2))]) + .sydg(&[QubitId(2)]) + .cz(&[(QubitId(2), QubitId(1))]) + .swap(&[(QubitId(0), QubitId(1))]); + }; + + for input in all_paulis(3) { + let mut sparse = sparse_prop_from_dense(&input); + let mut bitmask = bitmask_prop_from_dense(&input); + sequence(&mut sparse, &mut bitmask); + assert_eq!( + bitmask.dense_string(), + sparse.dense_string(), + "sequential composition: {input}" + ); + } } #[test] diff --git a/crates/pecos-simulators/src/density_matrix.rs b/crates/pecos-simulators/src/density_matrix.rs index 2ecb7695f..03aca37db 100644 --- a/crates/pecos-simulators/src/density_matrix.rs +++ b/crates/pecos-simulators/src/density_matrix.rs @@ -1505,6 +1505,41 @@ mod tests { assert!((dm.probability(2) - 1.0).abs() < 1e-10); } + #[test] + fn tensor_channel_expr_applies_to_noncontiguous_density_matrix_qubits() { + let mut dm = DensityMatrix::new(3); + let channel = ChannelExpr::Tensor(vec![ + pecos_core::channel::BitFlip(1.0, 0), + pecos_core::channel::BitFlip(1.0, 2), + ]); + + dm.apply_channel_expr(&channel).unwrap(); + + assert!(dm.probability(0) < 1e-10); + assert!((dm.probability(5) - 1.0).abs() < 1e-10); + } + + #[test] + fn out_of_range_channel_expr_is_rejected_without_mutating_state() { + let mut dm = DensityMatrix::new(2); + dm.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); + let before = dm.get_flattened_density_matrix(); + + let err = dm + .apply_channel_expr(&pecos_core::channel::BitFlip(0.5, 2)) + .expect_err("channel should not apply outside the simulator range"); + + assert!(matches!( + err, + ChannelError::QubitOutOfRange { + num_qubits: 2, + qubit: 2 + } + )); + let after = dm.get_flattened_density_matrix(); + assert_eq!(after, before); + } + #[test] fn state_vector_converts_to_density_matrix_and_back() { let mut state = StateVecSoA::new(2); diff --git a/crates/pecos-simulators/src/state_access.rs b/crates/pecos-simulators/src/state_access.rs index 674fda655..99caa1925 100644 --- a/crates/pecos-simulators/src/state_access.rs +++ b/crates/pecos-simulators/src/state_access.rs @@ -190,6 +190,10 @@ where R: Rng + ?Sized, { let dim = hilbert_dim(num_qubits)?; + if dim == 1 { + return Ok(vec![Complex64::new(1.0, 0.0)]); + } + loop { let mut state: Vec = (0..dim).map(|_| standard_complex_normal(rng)).collect(); let norm_sqr = state_norm_sqr(&state); @@ -237,6 +241,10 @@ pub trait DensityMatrixAccess: StateInfo { /// Returns one density-matrix element. /// + /// The default implementation materializes the full dense density matrix + /// and then reads one entry. Backends with cheaper direct element access + /// should override this method. + /// /// # Errors /// /// Returns an error if either index is outside the Hilbert space. @@ -411,6 +419,15 @@ where } } +impl StabilizerStateVectorConversion for DenseStab +where + R: Rng + SeedableRng + Debug + Clone, +{ + fn to_state_vector(&self) -> Result, StateAccessError> { + stabilizer_group_to_state_vector(&self.to_stabilizer_group()) + } +} + impl StabilizerStateVectorConversion for Stabilizer { fn to_state_vector(&self) -> Result, StateAccessError> { stabilizer_group_to_state_vector(&self.to_stabilizer_group()) @@ -1009,6 +1026,13 @@ mod tests { assert_ne!(state, different); } + #[test] + fn random_statevector_zero_qubits_is_scalar_identity_state() { + let mut rng = PecosRng::seed_from_u64(123); + let state = random_statevector(&mut rng, 0).unwrap(); + assert_state_vectors_close(&state, &[Complex64::new(1.0, 0.0)]); + } + #[test] fn random_statevector_haar_marginal_is_reasonable() { let mut rng = PecosRng::seed_from_u64(123); @@ -1128,7 +1152,16 @@ mod tests { state_vec.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); stab.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); - for pauli in [X(0) & X(1), Y(0) & Y(1), Z(0) & Z(1), X(0), Z(0)] { + for pauli in [ + X(0) & X(1), + Y(0) & Y(1), + Z(0) & Z(1), + X(0) & Z(1), + Y(0) & Z(1), + X(0) & Y(1), + X(0), + Z(0), + ] { let expected = state_vec.pauli_expectation(&pauli).unwrap(); let actual = stab.pauli_expectation(&pauli).unwrap(); assert_close(actual, expected); @@ -1142,13 +1175,49 @@ mod tests { state_vec.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); dense.h(&qid(0)).cx(&[(QubitId(0), QubitId(1))]); - for pauli in [X(0) & X(1), Y(0) & Y(1), Z(0) & Z(1), X(0), Z(0)] { + for pauli in [ + X(0) & X(1), + Y(0) & Y(1), + Z(0) & Z(1), + X(0) & Z(1), + Y(0) & Z(1), + X(0) & Y(1), + X(0), + Z(0), + ] { let expected = state_vec.pauli_expectation(&pauli).unwrap(); let actual = dense.pauli_expectation(&pauli).unwrap(); assert_close(actual, expected); } } + #[test] + fn stabilizer_pauli_expectations_match_state_vector_for_three_qubit_ghz() { + let mut state_vec = StateVec::new(3); + let mut sparse = SparseStab::new(3); + let mut dense = DenseStab::new(3); + let pairs = [(QubitId(0), QubitId(1)), (QubitId(0), QubitId(2))]; + state_vec.h(&qid(0)).cx(&pairs); + sparse.h(&qid(0)).cx(&pairs); + dense.h(&qid(0)).cx(&pairs); + + for pauli in [ + X(0) & X(1) & X(2), + Z(0) & Z(1), + Z(1) & Z(2), + Z(0) & Z(2), + Y(0) & Y(1) & X(2), + X(0), + Z(0), + ] { + let expected = state_vec.pauli_expectation(&pauli).unwrap(); + let sparse_actual = sparse.pauli_expectation(&pauli).unwrap(); + let dense_actual = dense.pauli_expectation(&pauli).unwrap(); + assert_close(sparse_actual, expected); + assert_close(dense_actual, expected); + } + } + #[test] fn sparse_stab_hybrid_supports_pauli_expectation_access() { let mut plus = SparseStabHybrid::new(1); @@ -1373,6 +1442,18 @@ mod tests { assert_state_vectors_close(&dense, &state_vec.state_vector().unwrap()); } + #[test] + fn dense_stabilizer_to_state_vector_matches_ghz_statevec() { + let mut dense = DenseStab::new(3); + let mut state_vec = StateVec::new(3); + let pairs = [(QubitId(0), QubitId(1)), (QubitId(0), QubitId(2))]; + dense.h(&qid(0)).cx(&pairs); + state_vec.h(&qid(0)).cx(&pairs); + + let dense_state = dense.to_state_vector().unwrap(); + assert_state_vectors_close(&dense_state, &state_vec.state_vector().unwrap()); + } + #[test] fn sparse_stabilizer_to_state_vector_preserves_complex_phase_state() { let mut sparse = SparseStab::new(1); diff --git a/crates/pecos/src/lib.rs b/crates/pecos/src/lib.rs index 44588d851..95244ce20 100644 --- a/crates/pecos/src/lib.rs +++ b/crates/pecos/src/lib.rs @@ -57,7 +57,7 @@ pub mod quantum { }; pub use pecos_quantum::{ Attribute, Circuit, CircuitMut, CustomGateError, DagCircuit, DagWouldCycleError, Gate, - GateHandle, GateType, GateView, QubitId, Tick, TickCircuit, + GateHandle, GateType, GateView, QubitId, Tick, TickCircuit, TickGateError, }; pub use pecos_quantum::{F2Matrix, PauliSequence, PauliSet, PauliStabilizerGroup}; } diff --git a/docs/user-guide/circuit-representation.md b/docs/user-guide/circuit-representation.md index a450cca23..f871e0547 100644 --- a/docs/user-guide/circuit-representation.md +++ b/docs/user-guide/circuit-representation.md @@ -400,6 +400,7 @@ A time-sliced circuit representation where gates are organized into discrete tim === ":fontawesome-brands-rust: Rust" ```rust + use pecos::core::Gate; use pecos::quantum::TickCircuit; let mut circuit = TickCircuit::new(); @@ -445,7 +446,9 @@ TickCircuit prevents scheduling conflicting gates in the same tick: // tick.cx(&[(0, 1)]); // Use try_add_gate for fallible operations - if let Err(e) = tick.try_add_gate(Gate::cx(&[(0, 1)])) { + if let Err(pecos::quantum::TickGateError::QubitConflict(e)) = + tick.try_add_gate(Gate::cx(&[(0, 1)])) + { println!("Conflict on qubits: {:?}", e.conflicting_qubits); } ``` @@ -651,7 +654,7 @@ A directed acyclic graph with topological ordering and cycle prevention: | `cx(pairs)`, `szz(pairs)`, `rzz(theta, pairs)` | Two-qubit gates | | `mz(qubits)`, `pz(qubits)` | Measurement and preparation | | `meta(key, value)` | Attach metadata to last gate | -| `gate_count()`, `depth()`, `width()` | Circuit metrics | +| `gate_count()`, `gate_node_count()`, `depth()`, `width()` | Circuit metrics | | `qubits()` | List of qubits used | | `topological_order()` | Gates in dependency order | | `layers()` | Iterator over parallel gate layers | @@ -665,6 +668,7 @@ A directed acyclic graph with topological ordering and cycle prevention: | `tick()` | Start a new time step | | `num_ticks()` | Number of time steps | | `gate_count()` | Total gates across all ticks | +| `gate_batch_count()` | Total compatible gate batches across all ticks | | `set_meta(key, value)` | Circuit-level metadata | ### DAG Methods diff --git a/docs/user-guide/quantum-operator-algebra.md b/docs/user-guide/quantum-operator-algebra.md index 0e3c8b89f..8e6b9025d 100644 --- a/docs/user-guide/quantum-operator-algebra.md +++ b/docs/user-guide/quantum-operator-algebra.md @@ -303,8 +303,8 @@ assert!(m.try_dg().is_none()); use pecos_core::op::*; let circuit = CX(0, 3) & H(5); -assert_eq!(circuit.num_qubits(), 6); // spans qubits 0..5 -assert_eq!(circuit.qubits(), vec![0, 1, 2, 3, 4, 5]); // full range +assert_eq!(circuit.num_qubits(), 6); // matrix span is qubits 0..5 +assert_eq!(circuit.qubits(), vec![0, 3, 5]); // actual support ``` --- diff --git a/python/pecos-rslib/src/dag_circuit_bindings.rs b/python/pecos-rslib/src/dag_circuit_bindings.rs index 1961eac83..26618fb27 100644 --- a/python/pecos-rslib/src/dag_circuit_bindings.rs +++ b/python/pecos-rslib/src/dag_circuit_bindings.rs @@ -25,7 +25,9 @@ use crate::dtypes::AngleParam; use crate::gate_registry_bindings::PyGateRegistry; use pecos_core::{Angle64, ChannelExpr, GateQubits, GateSignature, Pauli, TimeUnits}; -use pecos_quantum::{Attribute, DagCircuit, Gate, GateType, QubitId, Tick, TickCircuit}; +use pecos_quantum::{ + Attribute, DagCircuit, Gate, GateType, QubitId, Tick, TickCircuit, TickGateError, +}; use pyo3::prelude::*; use pyo3::types::{PyBytes, PyDict, PyList}; @@ -1014,8 +1016,10 @@ impl PyDagCircuit { /// Add a gate to the circuit. /// /// Returns the node index of the newly added gate. - fn add_gate(&mut self, gate: PyGate) -> usize { - self.inner.add_gate(gate.inner) + fn add_gate(&mut self, gate: PyGate) -> PyResult { + self.inner + .try_add_gate(gate.inner) + .map_err(pyo3::exceptions::PyValueError::new_err) } /// Remove a gate from the circuit. @@ -1724,6 +1728,28 @@ pyo3::create_exception!( pyo3::exceptions::PyValueError ); +fn tick_gate_error_to_pyerr(err: TickGateError, tick_idx: Option) -> PyErr { + match err { + TickGateError::QubitConflict(mut err) => { + if let Some(tick_idx) = tick_idx { + err.tick_idx = Some(tick_idx); + } + PyErr::new::(err.to_string()) + } + TickGateError::InvalidGate { + message, + tick_idx: err_tick_idx, + } => { + let tick_idx = tick_idx.or(err_tick_idx); + let msg = match tick_idx { + Some(tick_idx) => format!("Invalid gate in tick {tick_idx}: {message}"), + None => format!("Invalid gate: {message}"), + }; + PyErr::new::(msg) + } + } +} + /// Convert HUGR bytes to a `DagCircuit`. /// /// This function takes serialized HUGR data (JSON or binary envelope format) @@ -2132,8 +2158,10 @@ impl PyTick { /// Add a gate to this tick. /// /// Returns the index of the added gate within this tick. - fn add_gate(&mut self, gate: &PyGate) -> usize { - self.inner.add_gate(gate.inner.clone()) + fn add_gate(&mut self, gate: &PyGate) -> PyResult { + self.inner + .try_add_gate(gate.inner.clone()) + .map_err(|e| tick_gate_error_to_pyerr(e, None)) } /// Try to add a gate to this tick, returning an error if any qubit is already in use. @@ -2145,7 +2173,7 @@ impl PyTick { fn try_add_gate(&mut self, gate: &PyGate) -> PyResult { self.inner .try_add_gate(gate.inner.clone()) - .map_err(|e| PyErr::new::(e.to_string())) + .map_err(|e| tick_gate_error_to_pyerr(e, None)) } /// Remove all gates that use any of the specified qubits. @@ -2877,17 +2905,7 @@ impl PyTickHandle { self.last_gate_idx = Some(idx); Ok(()) } - Err(err) => { - let msg = format!( - "Qubit(s) {:?} already in use in tick {}", - err.conflicting_qubits - .iter() - .map(std::string::ToString::to_string) - .collect::>(), - self.tick_idx - ); - Err(PyErr::new::(msg)) - } + Err(err) => Err(tick_gate_error_to_pyerr(err, Some(self.tick_idx))), } } else { Ok(()) @@ -2902,17 +2920,7 @@ impl PyTickHandle { self.last_gate_idx = Some(idx); Ok(idx) } - Err(err) => { - let msg = format!( - "Qubit(s) {:?} already in use in tick {}", - err.conflicting_qubits - .iter() - .map(std::string::ToString::to_string) - .collect::>(), - self.tick_idx - ); - Err(PyErr::new::(msg)) - } + Err(err) => Err(tick_gate_error_to_pyerr(err, Some(self.tick_idx))), } } else { Ok(0) @@ -3443,17 +3451,7 @@ impl PyTickHandle { ); last_idx = Some(idx); } - Err(err) => { - let msg = format!( - "Qubit(s) {:?} already in use in tick {}", - err.conflicting_qubits - .iter() - .map(std::string::ToString::to_string) - .collect::>(), - tick_idx - ); - return Err(PyErr::new::(msg)); - } + Err(err) => return Err(tick_gate_error_to_pyerr(err, Some(tick_idx))), } } drop(circuit); @@ -3472,17 +3470,7 @@ impl PyTickHandle { slf.borrow_mut(py).last_gate_idx = Some(idx); Ok(slf) } - Err(err) => { - let msg = format!( - "Qubit(s) {:?} already in use in tick {}", - err.conflicting_qubits - .iter() - .map(std::string::ToString::to_string) - .collect::>(), - tick_idx - ); - Err(PyErr::new::(msg)) - } + Err(err) => Err(tick_gate_error_to_pyerr(err, Some(tick_idx))), } } } @@ -3559,17 +3547,7 @@ impl PyTickHandle { slf.borrow_mut(py).last_gate_idx = Some(idx); Ok(slf) } - Err(err) => { - let msg = format!( - "Qubit(s) {:?} already in use in tick {}", - err.conflicting_qubits - .iter() - .map(std::string::ToString::to_string) - .collect::>(), - tick_idx - ); - Err(PyErr::new::(msg)) - } + Err(err) => Err(tick_gate_error_to_pyerr(err, Some(tick_idx))), } } else { drop(circuit); diff --git a/python/pecos-rslib/src/pauli_bindings.rs b/python/pecos-rslib/src/pauli_bindings.rs index c0ab8c755..07a685d4c 100644 --- a/python/pecos-rslib/src/pauli_bindings.rs +++ b/python/pecos-rslib/src/pauli_bindings.rs @@ -494,10 +494,39 @@ impl PauliString { // ---- Tensor product operator (&) ---- /// Tensor product: `PauliString.X(0) & PauliString.Z(1)` - fn __and__(&self, other: &PauliString) -> Self { - PauliString { - inner: self.inner.clone() & other.inner.clone(), + fn __and__(&self, other: &PauliString) -> PyResult { + let mut lhs_qubits = self.inner.qubits(); + lhs_qubits.sort_unstable(); + lhs_qubits.dedup(); + + let mut rhs_qubits = other.inner.qubits(); + rhs_qubits.sort_unstable(); + rhs_qubits.dedup(); + + let mut overlap = Vec::new(); + let mut lhs_idx = 0; + let mut rhs_idx = 0; + while lhs_idx < lhs_qubits.len() && rhs_idx < rhs_qubits.len() { + match lhs_qubits[lhs_idx].cmp(&rhs_qubits[rhs_idx]) { + std::cmp::Ordering::Less => lhs_idx += 1, + std::cmp::Ordering::Greater => rhs_idx += 1, + std::cmp::Ordering::Equal => { + overlap.push(lhs_qubits[lhs_idx]); + lhs_idx += 1; + rhs_idx += 1; + } + } } + + if !overlap.is_empty() { + return Err(pyo3::exceptions::PyValueError::new_err(format!( + "tensor product requires disjoint Pauli support; overlapping qubits: {overlap:?}" + ))); + } + + Ok(PauliString { + inner: self.inner.clone() & other.inner.clone(), + }) } /// Pauli multiplication: `PauliString.X(0) * PauliString.Y(0)` diff --git a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock index 436a2117b..dcd1e1d96 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock +++ b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock @@ -2993,6 +2993,7 @@ dependencies = [ "pecos-core", "pecos-num", "pecos-random", + "serde_json", "smallvec", "tket", ] diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_circuit_representation.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_circuit_representation.rs index f86b85c0c..92d8e980f 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_circuit_representation.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_circuit_representation.rs @@ -8,7 +8,7 @@ fn test_user_guide_circuit_representation_rust_1() { use pecos::core::{Gate, QubitId}; use pecos::dag::DAG; use pecos::digraph::DiGraph; - use pecos::quantum::{Attribute, DagCircuit, TickCircuit}; + use pecos::quantum::{Attribute, DagCircuit, TickCircuit, TickGateError}; // Fluent builder API let mut circuit = DagCircuit::new(); @@ -182,7 +182,9 @@ tick.h(&[0]); // tick.cx(&[(0, 1)]); // Use try_add_gate for fallible operations -if let Err(e) = tick.try_add_gate(Gate::cx(&[(0, 1)])) { +if let Err(pecos::quantum::TickGateError::QubitConflict(e)) = + tick.try_add_gate(Gate::cx(&[(0, 1)])) +{ println!("Conflict on qubits: {:?}", e.conflicting_qubits); } diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_quantum_operator_algebra.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_quantum_operator_algebra.rs index 8e2c1daba..ba16ea200 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_quantum_operator_algebra.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_quantum_operator_algebra.rs @@ -223,8 +223,8 @@ fn test_user_guide_quantum_operator_algebra_rust_11() { fn test_user_guide_quantum_operator_algebra_rust_12() { use pecos_core::op::*; let circuit = CX(0, 3) & H(5); - assert_eq!(circuit.num_qubits(), 6); // spans qubits 0..5 - assert_eq!(circuit.qubits(), vec![0, 1, 2, 3, 4, 5]); // full range + assert_eq!(circuit.num_qubits(), 6); // matrix span is qubits 0..5 + assert_eq!(circuit.qubits(), vec![0, 3, 5]); // actual support } diff --git a/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py b/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py index 01a945a58..a539f667e 100644 --- a/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py +++ b/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py @@ -3,7 +3,7 @@ # Licensed under the Apache License, Version 2.0 import pytest -from pecos_rslib import Pauli, PauliString, X, Z +from pecos_rslib import Pauli, PauliString, X, Y, Z def test_pauli_string_from_str_accepts_dense_and_sparse_formats() -> None: @@ -14,6 +14,36 @@ def test_pauli_string_from_str_accepts_dense_and_sparse_formats() -> None: assert PauliString.from_str("X 0 X 1 Z 3") == expected +def test_pauli_string_common_representations_are_interchangeable_and_hash_equal() -> None: + from_constructors = X(0) & Y(2) & Z(5) + from_class_constructors = PauliString.X(0) & PauliString.Y(2) & PauliString.Z(5) + from_sparse = PauliString.from_str("X0 Y2 Z5") + from_explicit_sparse = PauliString.from_sparse_str("X0 Y2 Z5") + from_dense = PauliString.from_str("XIYIIZ") + from_explicit_dense = PauliString.from_dense_str("XIYIIZ") + from_tuples = PauliString([(Pauli.Z, 5), (Pauli.X, 0), (Pauli.Y, 2)]) + + forms = [ + from_constructors, + from_class_constructors, + from_sparse, + from_explicit_sparse, + from_dense, + from_explicit_dense, + from_tuples, + ] + assert all(form == from_constructors for form in forms) + assert len({hash(form) for form in forms}) == 1 + assert {form: idx for idx, form in enumerate(forms)} == {from_constructors: len(forms) - 1} + + +def test_pauli_string_tensor_result_is_pauli_string() -> None: + tensor = X(0) & Y(3) + + assert isinstance(tensor, PauliString) + assert tensor.get_paulis() == [(Pauli.X, 0), (Pauli.Y, 3)] + + def test_pauli_string_explicit_from_dense_and_sparse_formats() -> None: expected = X(0) & Z(3) @@ -56,6 +86,37 @@ def test_pauli_string_tuple_constructor_rejects_duplicate_qubits() -> None: assert PauliString([(Pauli.I, 0), (Pauli.X, 0)]) == X(0) +def test_pauli_string_tensor_rejects_overlapping_qubits() -> None: + with pytest.raises(ValueError, match="tensor product requires disjoint Pauli support"): + _ = X(0) & Z(0) + + with pytest.raises(ValueError, match=r"overlapping qubits: \[2\]"): + _ = (X(0) & Y(2)) & Z(2) + + +def test_pauli_string_composition_allows_same_qubit() -> None: + composed = X(0) * Z(0) + + assert composed.get_paulis() == [(Pauli.Y, 0)] + assert composed.get_phase() == 3 + + +def test_pauli_string_tensor_result_is_hashable() -> None: + tensor = X(0) & Y(3) + + assert {tensor: "xy"}[PauliString.from_sparse_str("X0 Y3")] == "xy" + + +def test_pauli_string_tensor_preserves_phase_through_string_roundtrip() -> None: + tensor = -X(0) & Z(1) + + assert tensor.get_phase() == 2 + assert tensor.to_sparse_str() == "-X0 Z1" + assert tensor.to_dense_str() == "-XZ" + assert PauliString.from_sparse_str(tensor.to_sparse_str()) == tensor + assert PauliString.from_dense_str(tensor.to_dense_str()) == tensor + + def test_quantum_namespace_exports_pauli_constructors() -> None: import pecos.quantum as quantum from pecos.quantum import pauli_string diff --git a/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py b/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py index 9d97d0f6e..1ef48572b 100644 --- a/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py +++ b/python/quantum-pecos/tests/pecos/test_quantum_info_bindings.py @@ -132,6 +132,58 @@ def test_choi_and_kraus_wrappers_round_trip_identity_channel() -> None: assert_close(process_fidelity(stinespring.to_kraus().to_ptm(), identity), 1.0) +def test_superop_compose_and_tensor_wrappers() -> None: + identity = Ptm.identity(1).to_superop() + x_channel = PauliChannel.one_qubit(1.0, 0.0, 0.0).to_ptm().to_superop() + + composed = x_channel.compose(x_channel) + assert isinstance(composed, SuperOp) + assert composed.num_qubits() == 1 + assert_matrix_close(composed.matrix(), identity.matrix()) + + tensor = identity.tensor(identity) + assert tensor.num_qubits() == 2 + assert_matrix_close( + tensor.matrix(), + [[1.0 + 0.0j if row == col else 0.0 + 0.0j for col in range(16)] for row in range(16)], + ) + + scalar_identity = Ptm.identity(0).to_superop() + assert scalar_identity.num_qubits() == 0 + assert_matrix_close(scalar_identity.matrix(), [[1.0 + 0.0j]]) + + with pytest.raises(ValueError, match="channel qubit count mismatch"): + identity.compose(tensor) + + +def test_zero_qubit_channel_wrappers_round_trip_scalar_identity() -> None: + identity = Ptm.identity(0) + + assert identity.num_qubits() == 0 + assert identity.matrix() == [[1.0]] + + choi = identity.to_choi() + assert choi.num_qubits() == 0 + assert_matrix_close(choi.matrix(), [[1.0 + 0.0j]]) + + kraus = identity.to_kraus() + assert kraus.num_qubits() == 0 + assert kraus.operators() == [[[1.0 + 0.0j]]] + + superop = identity.to_superop() + assert superop.num_qubits() == 0 + assert_matrix_close(superop.matrix(), [[1.0 + 0.0j]]) + + chi = identity.to_chi() + assert chi.num_qubits() == 0 + assert_matrix_close(chi.matrix(), [[1.0 + 0.0j]]) + + stinespring = kraus.to_stinespring() + assert stinespring.num_qubits() == 0 + assert stinespring.environment_dim() == 1 + assert_matrix_close(stinespring.isometry(), [[1.0 + 0.0j]]) + + def test_process_tomography_design_reconstructs_identity_channel() -> None: design = ProcessTomographyDesign.matrix_unit(1) @@ -154,6 +206,21 @@ def test_process_tomography_design_reconstructs_identity_channel() -> None: assert reconstructed.is_unital() +def test_process_tomography_design_reconstructs_random_two_qubit_channel() -> None: + channel = random_quantum_channel(2, 2, 321) + choi = channel.to_choi() + design = ProcessTomographyDesign.matrix_unit(2) + + assert design.dim() == 4 + assert design.num_inputs() == 16 + + outputs = design.simulate_outputs(choi) + reconstructed = design.reconstruct_choi(outputs) + + assert_matrix_close(reconstructed.matrix(), choi.matrix()) + assert reconstructed.is_cptp() + + def test_choi_from_matrix_unit_outputs_static_constructor() -> None: outputs = matrix_unit_basis(1) reconstructed = ChoiMatrix.from_matrix_unit_outputs(1, outputs) @@ -191,6 +258,45 @@ def test_state_measure_wrappers() -> None: assert_close(schmidt[1][0], 2.0**-0.5) +def test_quantum_info_wrappers_raise_value_errors_for_invalid_inputs() -> None: + with pytest.raises(ValueError, match="vector length mismatch"): + state_fidelity([1.0 + 0.0j], [1.0 + 0.0j, 0.0 + 0.0j]) + + with pytest.raises(ValueError, match="state vector squared norm"): + state_fidelity([1.0 + 0.0j, 1.0 + 0.0j], [1.0 + 0.0j, 0.0 + 0.0j]) + + with pytest.raises(ValueError, match="matrix must be square"): + purity([[1.0 + 0.0j, 0.0 + 0.0j]]) + + with pytest.raises(ValueError, match="probability distribution must sum"): + shannon_entropy([0.25, 0.25], 2.0) + + rho = [[1.0 + 0.0j, 0.0 + 0.0j], [0.0 + 0.0j, 0.0 + 0.0j]] + with pytest.raises(ValueError, match="duplicate subsystem"): + partial_trace_subsystems(rho, [2], [0, 0]) + + with pytest.raises(ValueError, match="outside"): + partial_trace_subsystems(rho, [2], [1]) + + with pytest.raises(ValueError, match="invalid subsystem dimensions"): + schmidt_decomposition([1.0 + 0.0j, 0.0 + 0.0j], [2, 2], [0]) + + with pytest.raises(ValueError, match="invalid matrix shape"): + SuperOp(1, [[1.0 + 0.0j]]) + + with pytest.raises(ValueError, match="not an isometry"): + Stinespring(1, [[2.0 + 0.0j, 0.0 + 0.0j], [0.0 + 0.0j, 2.0 + 0.0j]]) + + with pytest.raises(ValueError, match="qubit count mismatch"): + process_fidelity(Ptm.identity(1), Ptm.identity(2)) + + with pytest.raises(ValueError, match="qubit count mismatch"): + average_gate_fidelity(Ptm.identity(1), Ptm.identity(2)) + + with pytest.raises(ValueError, match="qubit count mismatch"): + gate_error(Ptm.identity(1), Ptm.identity(2)) + + def test_random_generators_are_seed_reproducible_and_valid() -> None: rho = random_density_matrix(1, 123) same_rho = random_density_matrix(1, 123) @@ -204,3 +310,9 @@ def test_random_generators_are_seed_reproducible_and_valid() -> None: same_channel = random_quantum_channel(1, 2, 123) assert channel.operators() == same_channel.operators() assert channel.is_trace_preserving() + + two_qubit = random_quantum_channel(2, 2, 125) + assert two_qubit.num_qubits() == 2 + assert two_qubit.is_trace_preserving() + assert two_qubit.to_superop().num_qubits() == 2 + assert len(two_qubit.to_superop().matrix()) == 16 From 1f1f4ec4902dcb6f710d0c77f80abb10763a6626 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 11:26:56 -0600 Subject: [PATCH 100/125] Consolidate cleanup review fixes and benchmarks --- Cargo.lock | 30 +- crates/benchmarks/benches/benchmarks.rs | 4 +- .../benches/modules/tick_circuit_layout.rs | 358 ++++++++++ .../fault_tolerance/dem_builder/builder.rs | 39 +- .../dem_builder/equivalence.rs | 245 ++++++- .../fault_tolerance/dem_builder/sampler.rs | 292 ++++++++- .../src/fault_tolerance/dem_builder/types.rs | 611 ++++++++++++++++-- .../src/fault_tolerance/fault_sampler.rs | 468 ++++++++++++++ .../targeted_lookup_decoder.rs | 57 ++ crates/pecos-quantum/src/tick_circuit.rs | 373 +++++++++++ .../src/bitmask_pauli_prop.rs | 245 +++++++ exp/pecos-lindblad/tests/four_qubit_smoke.rs | 69 ++ .../src/fault_tolerance_bindings.rs | 55 +- .../tests/pecos/test_pauli_string_bindings.py | 25 +- .../tests/qec/test_dem_sampler.py | 11 + .../tests/qec/test_parsed_dem_sampler.py | 20 + uv.lock | 256 ++++---- 17 files changed, 2948 insertions(+), 210 deletions(-) create mode 100644 crates/benchmarks/benches/modules/tick_circuit_layout.rs diff --git a/Cargo.lock b/Cargo.lock index 25a506045..d8cd88315 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -263,9 +263,9 @@ dependencies = [ [[package]] name = "assert_cmd" -version = "2.2.1" +version = "2.2.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "39bae1d3fa576f7c6519514180a72559268dd7d1fe104070956cb687bc6673bd" +checksum = "2aa3a22042e45de04255c7bf3626e239f450200fd0493c1e382263544b20aea6" dependencies = [ "anstyle", "bstr", @@ -538,6 +538,15 @@ dependencies = [ "rand 0.8.6", ] +[[package]] +name = "bs58" +version = "0.5.1" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "bf88ba1141d185c399bee5288d850d63b8369520c1eafc32a0430b5b6c287bf4" +dependencies = [ + "tinyvec", +] + [[package]] name = "bstr" version = "1.12.1" @@ -793,9 +802,9 @@ dependencies = [ [[package]] name = "clap_complete" -version = "4.6.3" +version = "4.6.4" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "660c0520455b1013b9bcb0393d5f643d7e4454fb69c915b8d6d2aa0e9a45acc3" +checksum = "e3e962dae2b1e5007fe9e3db363ddc43a8bf25546d279f7a8a4401204690e80c" dependencies = [ "clap 4.6.1", ] @@ -2482,9 +2491,9 @@ dependencies = [ [[package]] name = "hybrid-array" -version = "0.4.11" +version = "0.4.12" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "08d46837a0ed51fe95bd3b05de33cd64a1ee88fc797477ca48446872504507c5" +checksum = "9155a582abd142abc056962c29e3ce5ff2ad5469f4246b537ed42c5deba857da" dependencies = [ "typenum", ] @@ -6058,11 +6067,12 @@ dependencies = [ [[package]] name = "serde_with" -version = "3.19.0" +version = "3.20.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "f05839ce67618e14a09b286535c0d9c94e85ef25469b0e13cb4f844e5593eb19" +checksum = "e72c1c2cb7b223fafb600a619537a871c2818583d619401b785e7c0b746ccde2" dependencies = [ "base64", + "bs58", "chrono", "hex", "indexmap 1.9.3", @@ -6077,9 +6087,9 @@ dependencies = [ [[package]] name = "serde_with_macros" -version = "3.19.0" +version = "3.20.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "cf2ebbe86054f9b45bc3881e865683ccfaccce97b9b4cb53f3039d67f355a334" +checksum = "b90c488738ecb4fb0262f41f43bc40efc5868d9fb744319ddf5f5317f417bfac" dependencies = [ "darling", "proc-macro2", diff --git a/crates/benchmarks/benches/benchmarks.rs b/crates/benchmarks/benches/benchmarks.rs index c0d4afb9e..d496fa89b 100644 --- a/crates/benchmarks/benches/benchmarks.rs +++ b/crates/benchmarks/benches/benchmarks.rs @@ -45,6 +45,7 @@ mod modules { pub mod stabilizer_sims; pub mod state_vec_sims; pub mod surface_code; + pub mod tick_circuit_layout; pub mod trig; } @@ -60,7 +61,7 @@ use modules::{ allocation_overhead, cpu_stabilizer_comparison, dem_builder, dem_sampler, dod_statevec, fault_catalog, measurement_sampling, native_statevec_comparison, noise_models, pecos_neo_comparison, quizx_eval, rng, set_ops, sparse_stab_w_vs_y, sparse_state_vec, stab_vec, - stabilizer_sims, state_vec_sims, surface_code, trig, + stabilizer_sims, state_vec_sims, surface_code, tick_circuit_layout, trig, }; fn all_benchmarks(c: &mut Criterion) { @@ -89,6 +90,7 @@ fn all_benchmarks(c: &mut Criterion) { sparse_stab_vs_cpp::benchmarks(c); sparse_stab_w_vs_y::benchmarks(c); surface_code::benchmarks(c); + tick_circuit_layout::benchmarks(c); #[cfg(feature = "stab-tn")] stab_mps_vs_stab_vec::benchmarks(c); trig::benchmarks(c); diff --git a/crates/benchmarks/benches/modules/tick_circuit_layout.rs b/crates/benchmarks/benches/modules/tick_circuit_layout.rs new file mode 100644 index 000000000..2c8da7325 --- /dev/null +++ b/crates/benchmarks/benches/modules/tick_circuit_layout.rs @@ -0,0 +1,358 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! TickCircuit vs TickCircuitSoA layout benchmarks. +//! +//! These benchmarks measure the current representation tradeoff before making +//! any storage-refactor decision: +//! - direct TickCircuit traversal, +//! - TickCircuitSoA batched traversal, +//! - TickCircuit -> TickCircuitSoA conversion cost, and +//! - direct vs batched simulator execution with and without conversion cost. + +use criterion::{BenchmarkId, Criterion, Throughput, measurement::Measurement}; +use pecos_core::gate_type::GateType; +use pecos_quantum::{Gate, QubitId, TickCircuit, TickCircuitSoA}; +use pecos_simulators::{CircuitExecutor, CliffordGateable, SparseStab}; +use std::hint::black_box; + +const DISTANCES: &[usize] = &[3, 5, 7, 9, 11]; +const AMORTIZED_SHOTS: usize = 64; + +#[derive(Clone)] +struct LayoutSpec { + label: String, + num_qubits: usize, + gate_count: usize, + gate_batch_count: usize, + tick_circuit: TickCircuit, + soa_circuit: TickCircuitSoA, +} + +pub fn benchmarks(c: &mut Criterion) { + let specs = DISTANCES + .iter() + .map(|&distance| { + let rounds = distance; + let tick_circuit = build_surface_like_tick_circuit(distance, rounds); + let soa_circuit = TickCircuitSoA::from(&tick_circuit); + let num_qubits = surface_like_num_qubits(distance); + let gate_count = tick_circuit.gate_count(); + let gate_batch_count = tick_circuit.gate_batch_count(); + LayoutSpec { + label: format!("d{distance}_r{rounds}"), + num_qubits, + gate_count, + gate_batch_count, + tick_circuit, + soa_circuit, + } + }) + .collect::>(); + + bench_traversal(c, &specs); + bench_conversion(c, &specs); + bench_execution(c, &specs); + bench_amortized_execution(c, &specs); +} + +fn bench_traversal(c: &mut Criterion, specs: &[LayoutSpec]) { + let mut group = c.benchmark_group("tick_circuit_layout/traversal"); + + for spec in specs { + group.throughput(Throughput::Elements(spec.gate_count as u64)); + group.bench_with_input( + BenchmarkId::new("tick_circuit_iter_gates", &spec.label), + spec, + |b, spec| { + b.iter(|| black_box(traverse_tick_circuit(black_box(&spec.tick_circuit)))); + }, + ); + group.bench_with_input( + BenchmarkId::new("tick_circuit_soa_batched", &spec.label), + spec, + |b, spec| { + b.iter(|| black_box(traverse_tick_circuit_soa(black_box(&spec.soa_circuit)))); + }, + ); + } + + group.finish(); +} + +fn bench_conversion(c: &mut Criterion, specs: &[LayoutSpec]) { + let mut group = c.benchmark_group("tick_circuit_layout/conversion"); + + for spec in specs { + group.throughput(Throughput::Elements(spec.gate_count as u64)); + group.bench_with_input( + BenchmarkId::new( + format!("to_soa_{}_batches", spec.gate_batch_count), + &spec.label, + ), + spec, + |b, spec| { + b.iter(|| { + let soa = TickCircuitSoA::from(black_box(&spec.tick_circuit)); + black_box((soa.gate_count(), soa.gate_batch_count())) + }); + }, + ); + } + + group.finish(); +} + +fn bench_execution(c: &mut Criterion, specs: &[LayoutSpec]) { + let mut group = c.benchmark_group("tick_circuit_layout/execution_one_shot"); + + for spec in specs { + group.throughput(Throughput::Elements(spec.gate_count as u64)); + group.bench_with_input( + BenchmarkId::new("tick_circuit_direct", &spec.label), + spec, + |b, spec| { + b.iter(|| { + black_box(run_tick_circuit_direct( + black_box(&spec.tick_circuit), + spec.num_qubits, + )) + }); + }, + ); + group.bench_with_input( + BenchmarkId::new("soa_with_conversion", &spec.label), + spec, + |b, spec| { + b.iter(|| { + let soa = TickCircuitSoA::from(black_box(&spec.tick_circuit)); + black_box(run_tick_circuit_soa(black_box(&soa), spec.num_qubits)) + }); + }, + ); + group.bench_with_input( + BenchmarkId::new("soa_preconverted", &spec.label), + spec, + |b, spec| { + b.iter(|| { + black_box(run_tick_circuit_soa( + black_box(&spec.soa_circuit), + spec.num_qubits, + )) + }); + }, + ); + } + + group.finish(); +} + +fn bench_amortized_execution(c: &mut Criterion, specs: &[LayoutSpec]) { + let mut group = c.benchmark_group("tick_circuit_layout/execution_amortized_64_shots"); + + for spec in specs { + let throughput = spec.gate_count.saturating_mul(AMORTIZED_SHOTS); + group.throughput(Throughput::Elements(throughput as u64)); + group.bench_with_input( + BenchmarkId::new("tick_circuit_direct", &spec.label), + spec, + |b, spec| { + b.iter(|| { + let mut total = 0usize; + for _ in 0..AMORTIZED_SHOTS { + total = total.wrapping_add(run_tick_circuit_direct( + black_box(&spec.tick_circuit), + spec.num_qubits, + )); + } + black_box(total) + }); + }, + ); + group.bench_with_input( + BenchmarkId::new("soa_preconverted", &spec.label), + spec, + |b, spec| { + b.iter(|| { + let mut total = 0usize; + for _ in 0..AMORTIZED_SHOTS { + total = total.wrapping_add(run_tick_circuit_soa( + black_box(&spec.soa_circuit), + spec.num_qubits, + )); + } + black_box(total) + }); + }, + ); + } + + group.finish(); +} + +fn build_surface_like_tick_circuit(distance: usize, rounds: usize) -> TickCircuit { + let num_data = distance * distance; + let plaquettes = (distance - 1) * (distance - 1); + let x_ancilla_start = num_data; + let z_ancilla_start = x_ancilla_start + plaquettes; + let total_qubits = surface_like_num_qubits(distance); + + let mut circuit = TickCircuit::new(); + let data_qubits = (0..num_data).collect::>(); + let ancilla_qubits = (num_data..total_qubits).collect::>(); + let x_ancillas = (x_ancilla_start..z_ancilla_start).collect::>(); + let all_qubits = (0..total_qubits).collect::>(); + + circuit.tick().pz(&all_qubits); + circuit.tick().h(&data_qubits); + + for _ in 0..rounds { + circuit.tick().pz(&ancilla_qubits); + circuit.tick().h(&x_ancillas); + + for neighbor in 0..4 { + let pairs = surface_like_pairs_for_neighbor(distance, neighbor); + add_disjoint_cx_layers(&mut circuit, total_qubits, pairs); + } + + circuit.tick().h(&x_ancillas); + circuit.tick().mz(&ancilla_qubits); + } + + circuit.tick().mz(&data_qubits); + circuit +} + +fn surface_like_num_qubits(distance: usize) -> usize { + let num_data = distance * distance; + let plaquettes = (distance - 1) * (distance - 1); + num_data + 2 * plaquettes +} + +fn surface_like_pairs_for_neighbor(distance: usize, neighbor: usize) -> Vec<(usize, usize)> { + let num_data = distance * distance; + let plaquettes_per_type = (distance - 1) * (distance - 1); + let x_ancilla_start = num_data; + let z_ancilla_start = x_ancilla_start + plaquettes_per_type; + let mut pairs = Vec::with_capacity(2 * plaquettes_per_type); + + for row in 0..(distance - 1) { + for col in 0..(distance - 1) { + let plaquette = row * (distance - 1) + col; + let x_ancilla = x_ancilla_start + plaquette; + let z_ancilla = z_ancilla_start + plaquette; + let data = match neighbor { + 0 => row * distance + col, + 1 => (row + 1) * distance + col, + 2 => row * distance + col + 1, + 3 => (row + 1) * distance + col + 1, + _ => unreachable!("neighbor index is in 0..4"), + }; + + pairs.push((x_ancilla, data)); + pairs.push((data, z_ancilla)); + } + } + + pairs +} + +fn add_disjoint_cx_layers( + circuit: &mut TickCircuit, + num_qubits: usize, + mut remaining: Vec<(usize, usize)>, +) { + while !remaining.is_empty() { + let mut used = vec![false; num_qubits]; + let mut layer = Vec::new(); + let mut next = Vec::new(); + + for (control, target) in remaining { + if !used[control] && !used[target] { + used[control] = true; + used[target] = true; + layer.push((control, target)); + } else { + next.push((control, target)); + } + } + + circuit.tick().cx(&layer); + remaining = next; + } +} + +fn traverse_tick_circuit(circuit: &TickCircuit) -> usize { + let mut total = 0usize; + for (tick_idx, tick) in circuit.iter_ticks() { + total = total.wrapping_add(tick_idx); + for gate in tick.gates() { + total = total.wrapping_add(gate.num_gates()); + total = total.wrapping_add(gate.qubits.len()); + } + } + total +} + +fn traverse_tick_circuit_soa(circuit: &TickCircuitSoA) -> usize { + let mut total = 0usize; + for (tick_idx, tick) in circuit.iter_ticks_batched() { + total = total.wrapping_add(tick_idx); + for batch in tick.iter() { + total = total.wrapping_add(batch.gate_count()); + total = total.wrapping_add(batch.qubits().len()); + } + } + total +} + +fn run_tick_circuit_direct(circuit: &TickCircuit, num_qubits: usize) -> usize { + let mut sim = SparseStab::new(num_qubits); + let mut measurement_count = 0usize; + + for (_tick_idx, tick) in circuit.iter_ticks() { + for gate in tick.gates() { + measurement_count += execute_gate_direct(&mut sim, gate); + } + } + + measurement_count +} + +fn execute_gate_direct(sim: &mut S, gate: &Gate) -> usize { + match gate.gate_type { + GateType::PZ | GateType::QAlloc => { + sim.pz(&gate.qubits); + 0 + } + GateType::H => { + sim.h(&gate.qubits); + 0 + } + GateType::CX => { + let pairs = gate + .qubits + .chunks_exact(2) + .map(|pair| (pair[0], pair[1])) + .collect::>(); + sim.cx(&pairs); + 0 + } + GateType::MZ | GateType::MeasureFree => sim.mz(&gate.qubits).len(), + other => panic!("unsupported benchmark gate type: {other:?}"), + } +} + +fn run_tick_circuit_soa(circuit: &TickCircuitSoA, num_qubits: usize) -> usize { + let mut sim = SparseStab::new(num_qubits); + CircuitExecutor::new(circuit).run(&mut sim).len() +} diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs index 4265a0c47..9c36b0c16 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs @@ -937,6 +937,7 @@ impl<'a> DemBuilder<'a> { // Convert to pre-defined detector IDs using XOR let mut triggered_dets: SmallVec<[u32; 4]> = SmallVec::new(); let mut triggered_obs: SmallVec<[u32; 2]> = SmallVec::new(); + let mut triggered_tracked_ops: SmallVec<[u32; 2]> = SmallVec::new(); for dem_output_idx in self .influence_map @@ -944,6 +945,12 @@ impl<'a> DemBuilder<'a> { { xor_toggle_2(&mut triggered_obs, dem_output_idx); } + for tracked_op_idx in self + .influence_map + .get_tracked_op_indices(loc_idx, pauli.as_u8()) + { + xor_toggle_2(&mut triggered_tracked_ops, tracked_op_idx); + } for &rust_det in rust_dets { let meas_idx = rust_det as usize; @@ -966,8 +973,13 @@ impl<'a> DemBuilder<'a> { // Sort for canonical form triggered_dets.sort_unstable(); triggered_obs.sort_unstable(); + triggered_tracked_ops.sort_unstable(); - FaultMechanism::from_sorted(triggered_dets, triggered_obs) + FaultMechanism::from_sorted_with_tracked_ops( + triggered_dets, + triggered_obs, + triggered_tracked_ops, + ) } } @@ -1423,7 +1435,10 @@ mod tests { "+X0" ); assert!(!dem.to_string().contains("logical_observable")); - assert!(dem.to_pecos_string().contains("pecos_tracked_op")); + assert!(!dem.to_string().contains("TP0")); + let pecos_text = dem.to_pecos_string(); + assert!(pecos_text.contains("TP0")); + assert!(pecos_text.contains("pecos_tracked_op")); } #[test] @@ -1454,7 +1469,10 @@ mod tests { let dem_str = dem.to_string(); assert!(dem_str.contains("logical_observable L0")); assert!(!dem_str.contains("logical_observable L1")); - assert!(dem.to_pecos_string().contains("pecos_tracked_op")); + assert!(!dem_str.contains("TP0")); + let pecos_text = dem.to_pecos_string(); + assert!(pecos_text.contains("TP0")); + assert!(pecos_text.contains("pecos_tracked_op")); let summaries = dem.contribution_effect_summaries(); assert!( summaries @@ -1462,16 +1480,23 @@ mod tests { .any(|summary| summary.effect.dem_outputs.as_slice() == [0]), "observable should remain L0" ); + assert!( + summaries + .iter() + .any(|summary| summary.effect.tracked_ops.as_slice() == [0]), + "tracked operator should remain TP0" + ); } #[test] fn test_tick_dag_tick_dem_keeps_detector_observable_and_tracked_operator_distinct() { - use pecos_core::pauli::Z; + use pecos_core::pauli::X; use pecos_quantum::{DagCircuit, TickCircuit}; let mut circuit = TickCircuit::new(); circuit.tick().pz(&[0, 1]); circuit.tick().h(&[0]); + circuit.tracked_operator_labeled("tracked_x0", X(0)); circuit.tick().mz(&[0, 1]); circuit.set_meta( "num_measurements", @@ -1483,8 +1508,6 @@ mod tests { circuit .add_observable_metadata(&[-1], Some(0), Some("L0")) .unwrap(); - circuit.tracked_operator_labeled("tracked_z0", Z(0)); - let round_tripped = TickCircuit::from(&DagCircuit::from(&circuit)); let dem = DemBuilder::from_tick_circuit(&round_tripped, 0.03, 0.0, 0.02, 0.0); @@ -1494,10 +1517,10 @@ mod tests { assert_eq!(dem.dem_outputs()[0].id, 0); assert_eq!(dem.num_tracked_ops(), 1); assert_eq!(dem.tracked_ops()[0].id, 0); - assert_eq!(dem.tracked_ops()[0].label.as_deref(), Some("tracked_z0")); + assert_eq!(dem.tracked_ops()[0].label.as_deref(), Some("tracked_x0")); assert_eq!( dem.tracked_ops()[0].pauli.as_ref().unwrap().to_sparse_str(), - "+Z0" + "+X0" ); let standard_text = dem.to_string(); diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs index 96a535835..b84f7c826 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs @@ -86,6 +86,7 @@ impl ParsedMechanism { components: vec![MechanismComponent { detectors, observables, + tracked_ops: Vec::new(), }], } } @@ -98,9 +99,10 @@ impl ParsedMechanism { /// Returns the combined effect of this mechanism (XOR of all components). #[must_use] - pub fn combined_effect(&self) -> (Vec, Vec) { + pub fn combined_effect(&self) -> (Vec, Vec, Vec) { let mut all_dets: BTreeSet = BTreeSet::new(); let mut all_obs: BTreeSet = BTreeSet::new(); + let mut all_tracked_ops: BTreeSet = BTreeSet::new(); for comp in &self.components { for &d in &comp.detectors { @@ -117,21 +119,30 @@ impl ParsedMechanism { all_obs.insert(o); } } + for &op in &comp.tracked_ops { + if all_tracked_ops.contains(&op) { + all_tracked_ops.remove(&op); + } else { + all_tracked_ops.insert(op); + } + } } // BTreeSet is already sorted, so just collect let dets: Vec = all_dets.into_iter().collect(); let obs: Vec = all_obs.into_iter().collect(); - (dets, obs) + let tracked_ops: Vec = all_tracked_ops.into_iter().collect(); + (dets, obs, tracked_ops) } /// Creates an effect key for this mechanism (for aggregation). #[must_use] pub fn effect_key(&self) -> EffectKey { - let (dets, obs) = self.combined_effect(); + let (dets, obs, tracked_ops) = self.combined_effect(); EffectKey { detectors: dets, observables: obs, + tracked_ops, } } @@ -149,6 +160,9 @@ impl ParsedMechanism { for &o in &comp.observables { tokens.push(format!("L{o}")); } + for &op in &comp.tracked_ops { + tokens.push(format!("TP{op}")); + } tokens.join(" ") }) .collect(); @@ -163,6 +177,8 @@ pub struct MechanismComponent { pub detectors: Vec, /// Observable IDs in this component. pub observables: Vec, + /// PECOS tracked-Pauli operator IDs in this component. + pub tracked_ops: Vec, } /// Key for aggregating mechanisms by their effect. @@ -172,6 +188,8 @@ pub struct EffectKey { pub detectors: Vec, /// Sorted observable IDs. pub observables: Vec, + /// Sorted tracked-Pauli operator IDs. + pub tracked_ops: Vec, } impl EffectKey { @@ -183,6 +201,7 @@ impl EffectKey { Self { detectors, observables, + tracked_ops: Vec::new(), } } } @@ -196,6 +215,9 @@ impl fmt::Display for EffectKey { for &o in &self.observables { parts.push(format!("L{o}")); } + for &op in &self.tracked_ops { + parts.push(format!("TP{op}")); + } if parts.is_empty() { write!(f, "(empty)") } else { @@ -262,7 +284,7 @@ impl ParsedDem { /// Number of tracked operators. #[must_use] pub fn num_tracked_ops(&self) -> u32 { - u32::try_from(self.tracked_ops.iter().flatten().count()).unwrap_or(u32::MAX) + u32::try_from(self.tracked_ops.len()).unwrap_or(u32::MAX) } fn record_metadata(ops: &mut Vec>, op: DemOutput) { @@ -317,6 +339,7 @@ impl ParsedDem { fn parse_component(s: &str) -> Result { let mut detectors = Vec::new(); let mut observables = Vec::new(); + let mut tracked_ops = Vec::new(); for token in s.split_whitespace() { if let Some(id_str) = token.strip_prefix('D') { @@ -329,16 +352,24 @@ impl ParsedDem { .parse() .map_err(|_| DemParseError::InvalidObservableId(token.to_string()))?; observables.push(id); + } else if let Some(id_str) = token.strip_prefix("TP") { + let id: u32 = id_str + .parse() + .map_err(|_| DemParseError::InvalidTrackedOpId(token.to_string()))?; + tracked_ops.push(id); + } else { + return Err(DemParseError::InvalidTarget(token.to_string())); } - // Skip unknown tokens } detectors.sort_unstable(); observables.sort_unstable(); + tracked_ops.sort_unstable(); Ok(MechanismComponent { detectors, observables, + tracked_ops, }) } @@ -374,7 +405,9 @@ impl ParsedDem { if mech.is_decomposed() { // For decomposed mechanisms, each component fires independently for comp in &mech.components { - let key = EffectKey::new(comp.detectors.clone(), comp.observables.clone()); + let mut key = EffectKey::new(comp.detectors.clone(), comp.observables.clone()); + key.tracked_ops.clone_from(&comp.tracked_ops); + key.tracked_ops.sort_unstable(); aggregated .entry(key) .and_modify(|p| *p = combine_probabilities(*p, mech.probability)) @@ -470,7 +503,7 @@ impl ParsedDem { // Use combined_effect() to get the union of all detectors/observables // since all components fire together when the error occurs let mechanisms = self.mechanisms.iter().map(|mech| { - let (dets, obs) = mech.combined_effect(); + let (dets, obs, _tracked_ops) = mech.combined_effect(); (mech.probability, dets, obs) }); @@ -479,7 +512,43 @@ impl ParsedDem { self.num_detectors as usize, self.num_dem_outputs as usize, ); + let dem_outputs = self + .dem_outputs + .iter() + .enumerate() + .map(|(id, output)| { + output.clone().or_else(|| { + #[allow(clippy::cast_possible_truncation)] + // parsed DEM output count fits in u32 + { + Some( + DemOutput::new(id as u32) + .with_kind(crate::fault_tolerance::DemOutputKind::Observable), + ) + } + }) + }) + .collect(); + let tracked_ops = self + .tracked_ops + .iter() + .enumerate() + .map(|(id, output)| { + output.clone().or_else(|| { + #[allow(clippy::cast_possible_truncation)] + // parsed tracked-op count fits in u32 + { + Some( + DemOutput::new(id as u32) + .with_kind(crate::fault_tolerance::DemOutputKind::TrackedOperator), + ) + } + }) + }) + .collect(); + super::sampler::DemSampler::from_engine(engine) + .with_dem_output_metadata(dem_outputs, tracked_ops) } /// Convert to a decomposed (graphlike) DEM string. @@ -564,6 +633,7 @@ impl FromStr for ParsedDem { let mut mechanisms = Vec::new(); let mut max_det: i32 = -1; let mut max_obs: i32 = -1; + let mut max_tracked_op: i32 = -1; let mut dem_outputs: Vec> = Vec::new(); let mut tracked_ops: Vec> = Vec::new(); @@ -593,6 +663,12 @@ impl FromStr for ParsedDem { max_obs = max_obs.max(o as i32); } } + for &op in &comp.tracked_ops { + #[allow(clippy::cast_possible_wrap)] // tracked-op ID fits in i32 + { + max_tracked_op = max_tracked_op.max(op as i32); + } + } } mechanisms.push(mech); @@ -624,6 +700,10 @@ impl FromStr for ParsedDem { let op = parse_pecos_dem_metadata_line(line) .map_err(|err| DemParseError::InvalidPecosMetadata(err.to_string()))?; if op.is_tracked_operator() { + #[allow(clippy::cast_possible_wrap)] // tracked-op ID fits in i32 + { + max_tracked_op = max_tracked_op.max(op.id as i32); + } Self::record_metadata(&mut tracked_ops, op); } else { #[allow(clippy::cast_possible_wrap)] // observable ID fits in i32 @@ -649,6 +729,12 @@ impl FromStr for ParsedDem { dem_outputs.resize(max_obs as usize + 1, None); } } + if max_tracked_op >= 0 { + #[allow(clippy::cast_sign_loss)] // guarded by >= 0 check + { + tracked_ops.resize(max_tracked_op as usize + 1, None); + } + } Ok(Self { mechanisms, @@ -689,6 +775,10 @@ pub enum DemParseError { InvalidDetectorId(String), /// Invalid observable ID. InvalidObservableId(String), + /// Invalid tracked-Pauli operator ID. + InvalidTrackedOpId(String), + /// Invalid target token in an error line. + InvalidTarget(String), /// Invalid PECOS DEM-superset metadata. InvalidPecosMetadata(String), } @@ -700,6 +790,8 @@ impl std::fmt::Display for DemParseError { Self::InvalidProbability(s) => write!(f, "Invalid probability: {s}"), Self::InvalidDetectorId(s) => write!(f, "Invalid detector ID: {s}"), Self::InvalidObservableId(s) => write!(f, "Invalid observable ID: {s}"), + Self::InvalidTrackedOpId(s) => write!(f, "Invalid tracked Pauli ID: {s}"), + Self::InvalidTarget(s) => write!(f, "Invalid DEM error target: {s}"), Self::InvalidPecosMetadata(s) => write!(f, "Invalid PECOS DEM metadata: {s}"), } } @@ -1166,7 +1258,7 @@ mod tests { #[test] fn test_parse_accepts_pecos_dem_superset_metadata() { let dem_str = r#" - error(0.02) D0 + error(0.02) D0 TP0 pecos_tracked_op {"id":0,"kind":"tracked_operator","label":"track","pauli":"+X0 Z2","records":[]} "#; let dem = ParsedDem::from_str(dem_str).unwrap(); @@ -1176,6 +1268,9 @@ mod tests { assert_eq!(dem.num_dem_outputs(), 0); assert_eq!(dem.num_observables(), 0); assert_eq!(dem.num_tracked_ops(), 1); + assert_eq!(dem.mechanisms[0].components[0].tracked_ops, vec![0]); + assert_eq!(dem.mechanisms[0].format_targets(), "D0 TP0"); + assert_eq!(dem.mechanisms[0].effect_key().to_string(), "D0 TP0"); let op = dem.tracked_ops[0].as_ref().unwrap(); assert_eq!(op.label.as_deref(), Some("track")); assert_eq!( @@ -1191,6 +1286,102 @@ mod tests { assert!(matches!(err, DemParseError::InvalidPecosMetadata(_))); } + #[test] + fn test_parse_accepts_tracked_pauli_targets_without_metadata() { + let dem = ParsedDem::from_str("error(0.125) D1 L0 TP2").unwrap(); + + assert_eq!(dem.num_detectors, 2); + assert_eq!(dem.num_dem_outputs(), 1); + assert_eq!(dem.num_tracked_ops(), 3); + assert_eq!(dem.mechanisms[0].components[0].detectors, vec![1]); + assert_eq!(dem.mechanisms[0].components[0].observables, vec![0]); + assert_eq!(dem.mechanisms[0].components[0].tracked_ops, vec![2]); + assert_eq!(dem.mechanisms[0].effect_key().to_string(), "D1 L0 TP2"); + } + + #[test] + fn test_decomposed_tracked_pauli_targets_xor_by_parity() { + let cancels = ParsedDem::from_str("error(0.5) TP0 ^ TP0").unwrap(); + let (dets, obs, tracked_ops) = cancels.mechanisms[0].combined_effect(); + assert!(dets.is_empty()); + assert!(obs.is_empty()); + assert!(tracked_ops.is_empty()); + assert_eq!(cancels.mechanisms[0].effect_key().to_string(), "(empty)"); + + let leaves_detector = ParsedDem::from_str("error(0.5) D0 TP0 ^ TP0").unwrap(); + let (dets, obs, tracked_ops) = leaves_detector.mechanisms[0].combined_effect(); + assert_eq!(dets, vec![0]); + assert!(obs.is_empty()); + assert!(tracked_ops.is_empty()); + assert_eq!(leaves_detector.mechanisms[0].effect_key().to_string(), "D0"); + } + + #[test] + fn test_duplicate_tracked_pauli_targets_cancel_by_parity() { + let dem = ParsedDem::from_str("error(0.1) TP0 TP0").unwrap(); + assert_eq!(dem.mechanisms[0].components[0].tracked_ops, vec![0, 0]); + + let (dets, obs, tracked_ops) = dem.mechanisms[0].combined_effect(); + assert!(dets.is_empty()); + assert!(obs.is_empty()); + assert!(tracked_ops.is_empty()); + assert_eq!(dem.mechanisms[0].effect_key().to_string(), "(empty)"); + } + + #[test] + fn test_parse_rejects_unknown_error_targets() { + let err = ParsedDem::from_str("error(0.125) D1 T0").unwrap_err(); + assert!(matches!(err, DemParseError::InvalidTarget(_))); + assert!(err.to_string().contains("Invalid DEM error target: T0")); + } + + #[test] + fn test_parse_rejects_malformed_tracked_pauli_targets() { + for target in ["TP", "TPx", "TP-1"] { + let err = ParsedDem::from_str(&format!("error(0.125) {target}")).unwrap_err(); + assert!( + matches!(err, DemParseError::InvalidTrackedOpId(_)), + "{target} should be rejected as a malformed tracked-Pauli target" + ); + } + } + + #[test] + fn test_parsed_dem_sampler_projects_tracked_pauli_effects_but_keeps_metadata() { + let dem = ParsedDem::from_str("error(1.0) TP0").unwrap(); + let sampler = dem.to_dem_sampler(); + let mut rng = PecosRng::seed_from_u64(123); + + assert_eq!(dem.num_tracked_ops(), 1); + assert_eq!(sampler.num_detectors(), 0); + assert_eq!(sampler.num_dem_outputs(), 0); + assert_eq!(sampler.num_tracked_ops(), 1); + let (detectors, dem_outputs) = sampler.sample(&mut rng); + assert!(detectors.is_empty()); + assert!(dem_outputs.is_empty()); + let err = sampler.sample_tracked_operator_flips(&mut rng).unwrap_err(); + assert_eq!(err.backend(), "DemSampler"); + assert_eq!(err.num_tracked_ops(), 1); + } + + #[test] + fn test_parsed_dem_samplers_project_different_tracked_ops_the_same() { + let dem1 = ParsedDem::from_str("error(1.0) D0 TP0").unwrap(); + let dem2 = ParsedDem::from_str("error(1.0) D0 TP1").unwrap(); + let sampler1 = dem1.to_dem_sampler(); + let sampler2 = dem2.to_dem_sampler(); + let mut rng1 = PecosRng::seed_from_u64(11); + let mut rng2 = PecosRng::seed_from_u64(11); + + assert_eq!(sampler1.num_detectors(), 1); + assert_eq!(sampler2.num_detectors(), 1); + assert_eq!(sampler1.num_dem_outputs(), 0); + assert_eq!(sampler2.num_dem_outputs(), 0); + assert_eq!(sampler1.num_tracked_ops(), 1); + assert_eq!(sampler2.num_tracked_ops(), 2); + assert_eq!(sampler1.sample(&mut rng1), sampler2.sample(&mut rng2)); + } + #[test] fn test_parse_rejects_unknown_pecos_dem_extension() { let err = ParsedDem::from_str("pecos_old_extension {}").unwrap_err(); @@ -1246,6 +1437,41 @@ error(0.02) D1 D2 assert!(!result.details.only_in_dem2.is_empty()); } + #[test] + fn test_compare_exact_distinguishes_tracked_pauli_targets() { + let dem1 = ParsedDem::from_str("error(0.01) D0 TP0").unwrap(); + let dem2 = ParsedDem::from_str("error(0.01) D0 TP1").unwrap(); + + let result = compare_dems_exact(&dem1, &dem2, 1e-6); + assert!(!result.equivalent); + assert_eq!( + result + .details + .only_in_dem1 + .iter() + .map(ToString::to_string) + .collect::>(), + ["D0 TP0"] + ); + assert_eq!( + result + .details + .only_in_dem2 + .iter() + .map(ToString::to_string) + .collect::>(), + ["D0 TP1"] + ); + + let decomposed1 = ParsedDem::from_str("error(0.01) D0 TP0 ^ D1").unwrap(); + let decomposed2 = ParsedDem::from_str("error(0.01) D0 TP1 ^ D1").unwrap(); + let result = compare_dems_exact(&decomposed1, &decomposed2, 1e-6); + assert!( + !result.equivalent, + "exact PECOS DEM comparison must include tracked targets on decomposed components" + ); + } + #[test] fn test_statistical_comparison() { let dem_str = "error(0.5) D0"; @@ -1289,9 +1515,10 @@ error(0.02) D1 D2 let dem = ParsedDem::from_str("error(0.5) D0 ^ D0").unwrap(); // The combined effect should be empty - let (dets, obs) = dem.mechanisms[0].combined_effect(); + let (dets, obs, tracked_ops) = dem.mechanisms[0].combined_effect(); assert!(dets.is_empty()); assert!(obs.is_empty()); + assert!(tracked_ops.is_empty()); // Sample and verify D0 never fires let mut rng = PecosRng::seed_from_u64(42); diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs index b99f75136..1dd24cf98 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs @@ -97,6 +97,49 @@ impl std::fmt::Display for DetectorValidationError { impl std::error::Error for DetectorValidationError {} +/// Error returned when a sampler backend is asked to directly evaluate tracked +/// operators it only preserves as metadata. +#[derive(Debug, Clone, PartialEq, Eq)] +pub struct TrackedOperatorSamplingError { + backend: &'static str, + num_tracked_ops: usize, +} + +impl TrackedOperatorSamplingError { + fn new(backend: &'static str, num_tracked_ops: usize) -> Self { + Self { + backend, + num_tracked_ops, + } + } + + /// Backend that rejected direct tracked-operator sampling. + #[must_use] + pub fn backend(&self) -> &'static str { + self.backend + } + + /// Number of tracked operators carried as metadata by that backend. + #[must_use] + pub fn num_tracked_ops(&self) -> usize { + self.num_tracked_ops + } +} + +impl std::fmt::Display for TrackedOperatorSamplingError { + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + write!( + f, + "{} cannot directly sample tracked operator flips for {} tracked operator(s). \ + This backend samples decoder-facing detectors and observables only; tracked \ + operators are preserved as PECOS metadata and fault effects.", + self.backend, self.num_tracked_ops + ) + } +} + +impl std::error::Error for TrackedOperatorSamplingError {} + /// Output mode for the unified sampler. #[derive(Debug, Clone, Copy, PartialEq, Eq)] pub enum OutputMode { @@ -476,6 +519,24 @@ impl DemSampler { sampler } + /// Attach observable and tracked-operator metadata to an existing sampler. + /// + /// This is useful for parser paths where the sampling engine projects to + /// detector/observable columns but the original PECOS DEM still declared + /// tracked operators in a separate ID space. + #[must_use] + pub fn with_dem_output_metadata( + mut self, + dem_outputs: Vec>, + tracked_ops: Vec>, + ) -> Self { + self.labels.dem_outputs = dem_outputs; + self.labels.dem_output_labels = labels_from_dem_outputs(&self.labels.dem_outputs); + self.labels.tracked_ops = tracked_ops; + self.labels.tracked_op_labels = labels_from_dem_outputs(&self.labels.tracked_ops); + self + } + /// Reconstruct a detector error model from the compiled mechanism table. /// /// The returned model contains mechanism probabilities and effects. Higher @@ -543,7 +604,7 @@ impl DemSampler { /// Number of tracked operators. #[must_use] pub fn num_tracked_ops(&self) -> usize { - self.labels.tracked_ops.iter().flatten().count() + self.labels.tracked_ops.len() } /// Standard observable `L` IDs selected from this sampler. @@ -553,9 +614,68 @@ impl DemSampler { } /// PECOS tracked-operator IDs selected from this sampler. - #[must_use] - pub fn tracked_operator_ids(&self) -> Vec { - Vec::new() + /// + /// Decoder-facing DEM samplers do not directly evaluate tracked operators: + /// tracked operators are preserved in metadata and in PECOS DEM fault + /// effects, but the sampled bit columns are detectors plus standard + /// observable `L` outputs only. + /// + /// # Errors + /// + /// Returns [`TrackedOperatorSamplingError`] when tracked operators are + /// present and the caller is asking for a direct sampled tracked-operator + /// output space. + pub fn tracked_operator_ids(&self) -> Result, TrackedOperatorSamplingError> { + self.ensure_tracked_operator_sampling_supported()?; + Ok(Vec::new()) + } + + /// Sample direct tracked-operator flips. + /// + /// This returns an empty vector when the sampler carries no tracked + /// operators. If tracked operators are present, this backend fails + /// explicitly instead of returning silently empty data. + /// + /// # Errors + /// + /// Returns [`TrackedOperatorSamplingError`] when tracked operators are + /// present because [`DemSampler`] samples detector and observable columns, + /// not tracked-operator columns. + pub fn sample_tracked_operator_flips( + &self, + _rng: &mut R, + ) -> Result, TrackedOperatorSamplingError> { + self.ensure_tracked_operator_sampling_supported()?; + Ok(Vec::new()) + } + + /// Sample direct tracked-operator flips for multiple shots. + /// + /// # Errors + /// + /// Returns [`TrackedOperatorSamplingError`] when tracked operators are + /// present for the same reason as [`Self::sample_tracked_operator_flips`]. + pub fn sample_tracked_operator_batch( + &self, + num_shots: usize, + _rng: &mut R, + ) -> Result>, TrackedOperatorSamplingError> { + self.ensure_tracked_operator_sampling_supported()?; + Ok(vec![Vec::new(); num_shots]) + } + + fn ensure_tracked_operator_sampling_supported( + &self, + ) -> Result<(), TrackedOperatorSamplingError> { + let num_tracked_ops = self.num_tracked_ops(); + if num_tracked_ops == 0 { + Ok(()) + } else { + Err(TrackedOperatorSamplingError::new( + "DemSampler", + num_tracked_ops, + )) + } } /// Bit mask selecting observable outputs. @@ -1704,6 +1824,121 @@ mod tests { ); } + #[test] + fn sampler_paths_preserve_output_split_for_noiseless_and_forced_faults() { + use super::super::builder::DemBuilder; + use super::super::types::NoiseConfig; + use pecos_core::pauli::X; + use pecos_quantum::Attribute; + + fn assert_metadata(sampler: &DemSampler) { + assert_eq!(sampler.num_detectors(), 1); + assert_eq!(sampler.num_dem_outputs(), 1); + assert_eq!(sampler.num_observables(), 1); + assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!(sampler.observable_ids(), vec![0]); + let err = sampler.tracked_operator_ids().unwrap_err(); + assert_eq!(err.backend(), "DemSampler"); + assert_eq!(err.num_tracked_ops(), 1); + assert!( + err.to_string() + .contains("cannot directly sample tracked operator flips") + ); + assert_eq!( + sampler.labels().dem_outputs[0] + .as_ref() + .unwrap() + .label + .as_deref(), + Some("obs0") + ); + assert_eq!( + sampler.labels().tracked_ops[0] + .as_ref() + .unwrap() + .label + .as_deref(), + Some("tracked_x0") + ); + } + + fn sample_once(sampler: &DemSampler) -> (Vec, Vec) { + let mut rng = PecosRng::seed_from_u64(123); + sampler.sample(&mut rng) + } + + let mut circuit = DagCircuit::new(); + circuit.pz(&[0]); + let meas = circuit.mz(&[0]); + circuit.detector_labeled("det0", &[meas[0]]); + circuit.observable_labeled("obs0", &[meas[0]]); + circuit.tracked_operator_labeled("tracked_x0", X(0)); + circuit.set_attr("num_measurements", Attribute::String("1".to_string())); + circuit.set_attr( + "detectors", + Attribute::String(r#"[{"id":0,"records":[-1],"label":"det0"}]"#.to_string()), + ); + circuit.set_attr( + "observables", + Attribute::String(r#"[{"id":0,"records":[-1],"label":"obs0"}]"#.to_string()), + ); + + let noiseless = DemSampler::from_circuit(&circuit, &NoiseConfig::default()).unwrap(); + assert_metadata(&noiseless); + assert_eq!(sample_once(&noiseless), (vec![false], vec![false])); + + let forced_noise = NoiseConfig::new(0.0, 0.0, 1.0, 0.0); + let from_circuit = DemSampler::from_circuit(&circuit, &forced_noise).unwrap(); + assert_metadata(&from_circuit); + assert_eq!(sample_once(&from_circuit), (vec![true], vec![true])); + + let dem = DemBuilder::from_circuit(&circuit, 0.0, 0.0, 1.0, 0.0); + let from_dem = DemSampler::from_detector_error_model(&dem); + assert_metadata(&from_dem); + assert_eq!(sample_once(&from_dem), (vec![true], vec![true])); + + let influence_map = InfluenceBuilder::new(&circuit) + .with_circuit_annotations(&circuit) + .build(); + let from_builder = DemSamplerBuilder::new(&influence_map) + .with_noise(0.0, 0.0, 1.0, 0.0) + .with_detector_records(vec![vec![-1]]) + .with_observable_records(vec![vec![-1]]) + .build() + .unwrap(); + assert_metadata(&from_builder); + assert_eq!(sample_once(&from_builder), (vec![true], vec![true])); + } + + #[test] + fn sampler_xors_detectors_and_observables_while_tracked_ops_stay_metadata() { + use super::super::types::{DetectorDef, DetectorErrorModel, FaultMechanism}; + use pecos_core::pauli::Z; + + let mut dem = DetectorErrorModel::new(); + dem.add_detector(DetectorDef::new(0)); + dem.add_observable(DemOutput::new(0).with_records([-1]).with_label("L0")); + dem.add_tracked_operator(DemOutput::new(0).with_pauli(Z(3)).with_label("tracked_z3")); + dem.add_direct_contribution(FaultMechanism::from_unsorted([0], [0]), 1.0); + dem.add_direct_contribution(FaultMechanism::from_unsorted([0], []), 1.0); + + let sampler = DemSampler::from_detector_error_model(&dem); + let mut rng = PecosRng::seed_from_u64(99); + + assert_eq!(sampler.num_detectors(), 1); + assert_eq!(sampler.num_observables(), 1); + assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!( + sampler.labels().tracked_ops[0] + .as_ref() + .unwrap() + .label + .as_deref(), + Some("tracked_z3") + ); + assert_eq!(sampler.sample(&mut rng), (vec![false], vec![true])); + } + #[test] fn raw_mode_without_dem_outputs_reports_zero_dem_outputs() { let mut circuit = DagCircuit::new(); @@ -1744,12 +1979,59 @@ mod tests { let sampler = DemSampler::from_detector_error_model(&dem); assert_eq!(sampler.observable_ids(), vec![0]); - assert_eq!(sampler.tracked_operator_ids(), Vec::::new()); + assert_eq!( + sampler + .tracked_operator_ids() + .unwrap_err() + .num_tracked_ops(), + 1 + ); assert_eq!(sampler.observable_dem_output_mask(), 1); assert_eq!(sampler.observable_mask_from_dem_output_flips(&[false]), 0); assert_eq!(sampler.observable_mask_from_dem_output_flips(&[true]), 1); } + #[test] + fn tracked_operator_direct_sampling_fails_explicitly_when_unsupported() { + use super::super::types::{DetectorErrorModel, FaultMechanism}; + use pecos_core::pauli::X; + + let mut dem = DetectorErrorModel::new(); + dem.add_tracked_operator(DemOutput::new(0).with_pauli(X(0)).with_label("tracked_x0")); + dem.add_direct_contribution( + FaultMechanism::from_unsorted_with_tracked_ops([], [], [0]), + 0.25, + ); + + let sampler = DemSampler::from_detector_error_model(&dem); + let mut rng = PecosRng::seed_from_u64(17); + + let err = sampler + .sample_tracked_operator_flips(&mut rng) + .expect_err("DemSampler should reject direct tracked-op sampling"); + assert_eq!(err.backend(), "DemSampler"); + assert_eq!(err.num_tracked_ops(), 1); + assert!( + err.to_string() + .contains("samples decoder-facing detectors and observables only") + ); + + let err = sampler + .sample_tracked_operator_batch(4, &mut rng) + .expect_err("DemSampler should reject direct tracked-op batch sampling"); + assert_eq!(err.num_tracked_ops(), 1); + + let empty = DemSampler::from_detector_error_model(&DetectorErrorModel::new()); + assert_eq!( + empty.sample_tracked_operator_flips(&mut rng).unwrap(), + Vec::::new() + ); + assert_eq!( + empty.sample_tracked_operator_batch(3, &mut rng).unwrap(), + vec![Vec::::new(), Vec::new(), Vec::new()] + ); + } + #[test] fn high_noise_produces_nonzero_rates_both_modes() { let circuit = repetition_code(2); diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs index b04f42b4f..91bb9c2ec 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs @@ -524,6 +524,11 @@ pub struct FaultMechanism { /// /// New code should treat these as standard observable `L` output channels. pub dem_outputs: SmallVec<[u32; 2]>, + /// PECOS tracked-Pauli operator indices that flip together (sorted). + /// + /// These are rendered as `TP` only in PECOS DEM text. Standard DEM text + /// and decoder-facing mechanism tables intentionally ignore them. + pub tracked_ops: SmallVec<[u32; 2]>, } impl FaultMechanism { @@ -538,20 +543,43 @@ impl FaultMechanism { pub fn from_unsorted( detectors: impl IntoIterator, dem_outputs: impl IntoIterator, + ) -> Self { + Self::from_unsorted_with_tracked_ops(detectors, dem_outputs, std::iter::empty()) + } + + /// Creates a mechanism from unsorted detector, DEM-output, and tracked-Pauli indices. + #[must_use] + pub fn from_unsorted_with_tracked_ops( + detectors: impl IntoIterator, + dem_outputs: impl IntoIterator, + tracked_ops: impl IntoIterator, ) -> Self { let mut dets: SmallVec<[u32; 4]> = detectors.into_iter().collect(); let mut dem_outputs: SmallVec<[u32; 2]> = dem_outputs.into_iter().collect(); + let mut tracked_ops: SmallVec<[u32; 2]> = tracked_ops.into_iter().collect(); dets.sort_unstable(); dem_outputs.sort_unstable(); + tracked_ops.sort_unstable(); Self { detectors: dets, dem_outputs, + tracked_ops, } } /// Creates a mechanism from pre-sorted detector and DEM-output indices. #[must_use] pub fn from_sorted(detectors: SmallVec<[u32; 4]>, dem_outputs: SmallVec<[u32; 2]>) -> Self { + Self::from_sorted_with_tracked_ops(detectors, dem_outputs, SmallVec::new()) + } + + /// Creates a mechanism from pre-sorted detector, DEM-output, and tracked-Pauli indices. + #[must_use] + pub fn from_sorted_with_tracked_ops( + detectors: SmallVec<[u32; 4]>, + dem_outputs: SmallVec<[u32; 2]>, + tracked_ops: SmallVec<[u32; 2]>, + ) -> Self { debug_assert!( detectors.windows(2).all(|w| w[0] <= w[1]), "detectors must be sorted" @@ -560,9 +588,14 @@ impl FaultMechanism { dem_outputs.windows(2).all(|w| w[0] <= w[1]), "dem_outputs must be sorted" ); + debug_assert!( + tracked_ops.windows(2).all(|w| w[0] <= w[1]), + "tracked_ops must be sorted" + ); Self { detectors, dem_outputs, + tracked_ops, } } @@ -570,9 +603,29 @@ impl FaultMechanism { #[inline] #[must_use] pub fn is_empty(&self) -> bool { + self.detectors.is_empty() && self.dem_outputs.is_empty() && self.tracked_ops.is_empty() + } + + /// Returns true if this mechanism has no decoder-facing effect. + /// + /// This ignores PECOS tracked-Pauli effects, matching standard DEM and + /// decoder-facing sampler behavior. + #[inline] + #[must_use] + pub fn is_standard_empty(&self) -> bool { self.detectors.is_empty() && self.dem_outputs.is_empty() } + /// Returns the decoder-facing projection of this mechanism. + #[must_use] + pub fn standard_effect(&self) -> Self { + Self { + detectors: self.detectors.clone(), + dem_outputs: self.dem_outputs.clone(), + tracked_ops: SmallVec::new(), + } + } + /// Returns the number of detectors in this mechanism. #[inline] #[must_use] @@ -587,6 +640,13 @@ impl FaultMechanism { self.dem_outputs.len() } + /// Returns the number of tracked Pauli operator outputs in this mechanism. + #[inline] + #[must_use] + pub fn num_tracked_ops(&self) -> usize { + self.tracked_ops.len() + } + /// XOR this mechanism with another, returning the combined effect. /// /// Used when combining correlated errors (e.g., two-qubit gate errors). @@ -595,6 +655,7 @@ impl FaultMechanism { Self { detectors: symmetric_difference_4(&self.detectors, &other.detectors), dem_outputs: symmetric_difference_2(&self.dem_outputs, &other.dem_outputs), + tracked_ops: symmetric_difference_2(&self.tracked_ops, &other.tracked_ops), } } @@ -680,7 +741,9 @@ fn symmetric_difference_2(a: &SmallVec<[u32; 2]>, b: &SmallVec<[u32; 2]>) -> Sma impl PartialEq for FaultMechanism { fn eq(&self, other: &Self) -> bool { - self.detectors == other.detectors && self.dem_outputs == other.dem_outputs + self.detectors == other.detectors + && self.dem_outputs == other.dem_outputs + && self.tracked_ops == other.tracked_ops } } @@ -690,6 +753,7 @@ impl Hash for FaultMechanism { fn hash(&self, state: &mut H) { self.detectors.hash(state); self.dem_outputs.hash(state); + self.tracked_ops.hash(state); } } @@ -704,6 +768,7 @@ impl Ord for FaultMechanism { self.detectors .cmp(&other.detectors) .then_with(|| self.dem_outputs.cmp(&other.dem_outputs)) + .then_with(|| self.tracked_ops.cmp(&other.tracked_ops)) } } @@ -711,9 +776,10 @@ impl fmt::Debug for FaultMechanism { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!( f, - "FaultMechanism(dets={:?}, dem_outputs={:?})", + "FaultMechanism(dets={:?}, dem_outputs={:?}, tracked_ops={:?})", self.detectors.as_slice(), - self.dem_outputs.as_slice() + self.dem_outputs.as_slice(), + self.tracked_ops.as_slice() ) } } @@ -773,16 +839,17 @@ impl DecomposedFault { pub fn to_stim_targets(&self) -> String { self.components .iter() - .map(|comp| { - let mut targets = Vec::new(); - for &det in &comp.detectors { - targets.push(format!("D{det}")); - } - for &dem_output in &comp.dem_outputs { - targets.push(format!("L{dem_output}")); - } - targets.join(" ") - }) + .map(format_mechanism_targets) + .collect::>() + .join(" ^ ") + } + + /// Formats this error for PECOS DEM output, including tracked Pauli `TP` targets. + #[must_use] + pub fn to_pecos_targets(&self) -> String { + self.components + .iter() + .map(format_pecos_mechanism_targets) .collect::>() .join(" ^ ") } @@ -2662,20 +2729,66 @@ impl DetectorErrorModel { Ok(self) } - /// Converts the DEM to PECOS's strict superset of Stim DEM text. + /// Converts the DEM to PECOS DEM text. /// - /// The beginning of the output is exactly the standard Stim-compatible DEM - /// from [`Self::to_string`]. PECOS-only metadata follows as - /// `pecos_observable {json}` and `pecos_tracked_op {json}` statements. This makes PECOS DEM text a - /// strict superset: every Stim DEM remains valid PECOS DEM text, and PECOS - /// adds statements for data Stim cannot represent. + /// This format is a strict superset of standard DEM text. It uses `D` + /// detector targets and `L` measurement-defined observable targets as + /// usual, and adds PECOS-only `TP` tracked-Pauli targets for tracked + /// operator flips. Metadata follows as `pecos_observable {json}` and + /// `pecos_tracked_op {json}` statements. /// /// # Panics /// /// Panics only if serializing JSON values constructed in this method fails. #[must_use] pub fn to_pecos_string(&self) -> String { - let mut text = self.to_string(); + let mut lines = Vec::new(); + + for det in &self.detectors { + if let Some([x, y, z]) = det.coords { + lines.push(format!("detector({x}, {y}, {z}) D{}", det.id)); + } else { + lines.push(format!("detector D{}", det.id)); + } + } + + for obs in &self.observables { + lines.push(format!("logical_observable L{}", obs.id)); + } + + let mut by_effect: BTreeMap = BTreeMap::new(); + for contrib in &self.contributions { + by_effect + .entry(contrib.effect.clone()) + .and_modify(|p| *p = combine_independent_probs(*p, contrib.probability)) + .or_insert(contrib.probability); + } + + for (effect, total_prob) in by_effect { + if effect.is_empty() || total_prob <= 0.0 { + continue; + } + + let targets = format_pecos_mechanism_targets(&effect); + if !targets.is_empty() { + lines.push(format!( + "error({}) {}", + format_probability(total_prob), + targets + )); + } + } + + let metadata_lines = self.pecos_metadata_lines(); + + if metadata_lines.is_empty() { + return lines.join("\n"); + } + lines.extend(metadata_lines); + lines.join("\n") + } + + fn pecos_metadata_lines(&self) -> Vec { let observable_lines = self.observables.iter().map(|observable| { let value = pecos_metadata_dem_output_value(observable); let payload = serde_json::to_string(&value) @@ -2688,16 +2801,7 @@ impl DetectorErrorModel { .expect("serializing PECOS tracked-op metadata should not fail"); format!("pecos_tracked_op {payload}") }); - let metadata_lines: Vec = observable_lines.chain(tracked_op_lines).collect(); - - if metadata_lines.is_empty() { - return text; - } - if !text.is_empty() { - text.push('\n'); - } - text.push_str(&metadata_lines.join("\n")); - text + observable_lines.chain(tracked_op_lines).collect() } /// Applies PECOS metadata embedded in extended DEM text. @@ -3286,14 +3390,14 @@ impl DetectorErrorModel { let mut by_effect: BTreeMap = BTreeMap::new(); for contrib in &self.contributions { by_effect - .entry(contrib.effect.clone()) + .entry(contrib.effect.standard_effect()) .and_modify(|p| *p = combine_independent_probs(*p, contrib.probability)) .or_insert(contrib.probability); } let mechanisms: Vec<(f64, Vec, Vec)> = by_effect .into_iter() - .filter(|(effect, prob)| !effect.is_empty() && *prob > 0.0) + .filter(|(effect, prob)| !effect.is_standard_empty() && *prob > 0.0) .map(|(effect, prob)| (prob, effect.detectors.to_vec(), effect.dem_outputs.to_vec())) .collect(); @@ -3427,14 +3531,14 @@ impl DetectorErrorModel { let mut by_effect: BTreeMap = BTreeMap::new(); for contrib in &self.contributions { by_effect - .entry(contrib.effect.clone()) + .entry(contrib.effect.standard_effect()) .and_modify(|p| *p = combine_independent_probs(*p, contrib.probability)) .or_insert(contrib.probability); } // Output each mechanism with its total probability for (effect, total_prob) in by_effect { - if effect.is_empty() || total_prob <= 0.0 { + if effect.is_standard_empty() || total_prob <= 0.0 { continue; } @@ -3554,7 +3658,7 @@ impl DetectorErrorModel { return (cached.clone(), strategy, recorded_component_targets); } - let effect = &contrib.effect; + let effect = contrib.effect.standard_effect(); let (targets, strategy) = if let Some((x_effect, z_effect)) = contrib.decomposition_components() { @@ -3580,7 +3684,7 @@ impl DetectorErrorModel { }; (targets, ContributionRenderStrategy::SourceComponents) } else if effect.num_detectors() == 2 && effect.dem_outputs.is_empty() { - let direct_targets = Self::two_detector_direct_targets(effect, singleton_set); + let direct_targets = Self::two_detector_direct_targets(&effect, singleton_set); if matches!( two_detector_direct_policy, TwoDetectorDirectRenderPolicy::PreferRecordedComponents @@ -3610,7 +3714,7 @@ impl DetectorErrorModel { ) } } else if effect.is_hyperedge() { - if let Some(decomp) = graphlike_index.find_hyperedge_decomposition(effect) { + if let Some(decomp) = graphlike_index.find_hyperedge_decomposition(&effect) { ( Self::maybe_maximally_decompose_parts(decomp, singleton_set) .iter() @@ -3621,7 +3725,7 @@ impl DetectorErrorModel { ) } else { ( - format_mechanism_targets(effect), + format_mechanism_targets(&effect), ContributionRenderStrategy::EffectDirect, ) } @@ -3636,7 +3740,7 @@ impl DetectorErrorModel { ) } } else if effect.num_detectors() == 2 && effect.dem_outputs.is_empty() { - let direct_targets = Self::two_detector_direct_targets(effect, singleton_set); + let direct_targets = Self::two_detector_direct_targets(&effect, singleton_set); if matches!( two_detector_direct_policy, TwoDetectorDirectRenderPolicy::PreferRecordedComponents @@ -3666,7 +3770,7 @@ impl DetectorErrorModel { ) } } else if effect.is_hyperedge() { - if let Some(decomp) = graphlike_index.find_hyperedge_decomposition(effect) { + if let Some(decomp) = graphlike_index.find_hyperedge_decomposition(&effect) { ( Self::maybe_maximally_decompose_parts(decomp, singleton_set) .iter() @@ -3677,7 +3781,7 @@ impl DetectorErrorModel { ) } else { ( - format_mechanism_targets(effect), + format_mechanism_targets(&effect), ContributionRenderStrategy::EffectDirect, ) } @@ -3851,8 +3955,9 @@ impl DetectorErrorModel { fn collect_graphlike_mechanisms(&self) -> BTreeSet { let mut graphlike = BTreeSet::new(); for contrib in &self.contributions { - if contrib.effect.is_graphlike() { - graphlike.insert(contrib.effect.clone()); + let standard = contrib.effect.standard_effect(); + if !standard.is_standard_empty() && standard.is_graphlike() { + graphlike.insert(standard); } } graphlike @@ -3894,6 +3999,21 @@ fn format_mechanism_targets(mechanism: &FaultMechanism) -> String { targets.join(" ") } +/// Formats a PECOS DEM mechanism's targets, including tracked Pauli `TP` outputs. +fn format_pecos_mechanism_targets(mechanism: &FaultMechanism) -> String { + let mut targets = Vec::new(); + for &det in &mechanism.detectors { + targets.push(format!("D{det}")); + } + for &dem_output in &mechanism.dem_outputs { + targets.push(format!("L{dem_output}")); + } + for &tracked_op in &mechanism.tracked_ops { + targets.push(format!("TP{tracked_op}")); + } + targets.join(" ") +} + /// Combines two independent error probabilities. /// /// For two independent errors with probabilities p1 and p2, the combined @@ -3971,6 +4091,33 @@ mod tests { assert_eq!(m1.dem_outputs.as_slice(), &[0, 1]); } + #[test] + fn test_error_mechanism_equality_and_hash_include_tracked_ops() { + let standard = FaultMechanism::from_unsorted([0], []); + let with_tracked = FaultMechanism::from_unsorted_with_tracked_ops([0], [], [0]); + + assert_ne!(standard, with_tracked); + assert_eq!(standard.standard_effect(), with_tracked.standard_effect()); + + let mut set = std::collections::HashSet::new(); + set.insert(standard); + set.insert(with_tracked); + assert_eq!( + set.len(), + 2, + "internal mechanism identity must keep tracked operators distinct" + ); + } + + #[test] + fn test_pecos_target_format_canonicalizes_tracked_ops() { + let mechanism = FaultMechanism::from_unsorted_with_tracked_ops([], [], [2, 0]); + assert_eq!( + DecomposedFault::single(mechanism).to_pecos_targets(), + "TP0 TP2" + ); + } + #[test] fn test_combine_probabilities() { // Same probability twice @@ -4280,14 +4427,19 @@ mod tests { .with_pauli(X(0) & Z(2)) .with_label("track_check"), ); - dem.add_direct_contribution(FaultMechanism::from_unsorted([0], []), 0.01); + dem.add_direct_contribution( + FaultMechanism::from_unsorted_with_tracked_ops([0], [], [0]), + 0.01, + ); let stim_text = dem.to_string(); assert!(!stim_text.contains("logical_observable L0")); + assert!(stim_text.contains("error(0.01) D0")); + assert!(!stim_text.contains("TP0")); assert!(!stim_text.contains("pecos_")); let pecos_text = dem.to_pecos_string(); - assert!(pecos_text.starts_with(&stim_text)); + assert!(pecos_text.contains("error(0.01) D0 TP0")); assert!(pecos_text.contains("pecos_tracked_op")); assert!(pecos_text.contains(r#""kind":"tracked_operator""#)); assert!(pecos_text.contains(r#""pauli":"+X0 Z2""#)); @@ -4329,16 +4481,21 @@ mod tests { .with_pauli(Z(3)) .with_label("tracked_z3"), ); - dem.add_direct_contribution(FaultMechanism::from_unsorted([0], [0]), 0.01); + dem.add_direct_contribution( + FaultMechanism::from_unsorted_with_tracked_ops([0], [0], [0]), + 0.01, + ); dem.add_direct_contribution(FaultMechanism::from_unsorted([], [1]), 0.02); let stim_text = dem.to_string(); assert!(stim_text.contains("logical_observable L0")); assert!(stim_text.contains("logical_observable L1")); assert!(!stim_text.contains("logical_observable L2")); + assert!(!stim_text.contains("TP0")); assert!(!stim_text.contains("pecos_tracked_op")); let pecos_text = dem.to_pecos_string(); + assert!(pecos_text.contains("error(0.01) D0 L0 TP0")); assert!(pecos_text.contains("pecos_observable")); assert!(pecos_text.contains("pecos_tracked_op")); @@ -4378,6 +4535,365 @@ mod tests { ); } + #[test] + fn test_pecos_dem_text_parses_error_targets_and_metadata() { + use crate::fault_tolerance::dem_builder::ParsedDem; + use pecos_core::pauli::{X, Z}; + + let mut dem = DetectorErrorModel::new(); + dem.add_detector(DetectorDef::new(0).with_coords([1.0, 2.0, 3.0])); + dem.add_observable(DemOutput::new(0).with_records([-1]).with_label("L0")); + dem.add_tracked_operator( + DemOutput::new(0) + .with_pauli(X(0) & Z(2)) + .with_label("tracked_x0_z2"), + ); + dem.add_direct_contribution( + FaultMechanism::from_unsorted_with_tracked_ops([0], [0], [0]), + 0.25, + ); + + let pecos_text = dem.to_pecos_string(); + let parsed: ParsedDem = pecos_text.parse().unwrap(); + + assert_eq!(parsed.num_detectors, 1); + assert_eq!(parsed.num_dem_outputs(), 1); + assert_eq!(parsed.num_tracked_ops(), 1); + assert_eq!(parsed.mechanisms.len(), 1); + assert_eq!(parsed.mechanisms[0].format_targets(), "D0 L0 TP0"); + assert_eq!(parsed.mechanisms[0].components[0].detectors, vec![0]); + assert_eq!(parsed.mechanisms[0].components[0].observables, vec![0]); + assert_eq!(parsed.mechanisms[0].components[0].tracked_ops, vec![0]); + assert_eq!( + parsed.dem_outputs[0].as_ref().unwrap().label.as_deref(), + Some("L0") + ); + assert_eq!( + parsed.tracked_ops[0] + .as_ref() + .unwrap() + .pauli + .as_ref() + .unwrap() + .to_sparse_str(), + "+X0 Z2" + ); + } + + #[test] + fn test_tracked_only_contribution_is_pecos_only_and_decoder_invisible() { + use pecos_core::pauli::X; + + let mut dem = DetectorErrorModel::new(); + dem.add_tracked_operator(DemOutput::new(0).with_pauli(X(0)).with_label("tracked_x0")); + dem.add_direct_contribution( + FaultMechanism::from_unsorted_with_tracked_ops([], [], [0]), + 0.25, + ); + + let standard_text = dem.to_string(); + assert!(!standard_text.contains("error(")); + assert!(!standard_text.contains("TP0")); + assert!(!standard_text.contains("pecos_tracked_op")); + + let pecos_text = dem.to_pecos_string(); + assert!(pecos_text.contains("error(0.25) TP0")); + assert!(pecos_text.contains("pecos_tracked_op")); + + let (mechanisms, coords) = dem.to_mechanisms(); + assert!(mechanisms.is_empty()); + assert!(coords.is_empty()); + } + + #[test] + fn test_standard_projection_merges_effects_that_differ_only_by_tracked_ops() { + use pecos_core::pauli::{X, Z}; + + let mut dem = DetectorErrorModel::new(); + dem.add_detector(DetectorDef::new(0)); + dem.add_tracked_operator(DemOutput::new(0).with_pauli(X(0)).with_label("tracked_x0")); + dem.add_tracked_operator(DemOutput::new(1).with_pauli(Z(0)).with_label("tracked_z0")); + dem.add_direct_contribution( + FaultMechanism::from_unsorted_with_tracked_ops([0], [], [0]), + 0.1, + ); + dem.add_direct_contribution( + FaultMechanism::from_unsorted_with_tracked_ops([0], [], [1]), + 0.2, + ); + + let standard_text = dem.to_string(); + let error_lines = standard_text + .lines() + .filter(|line| line.starts_with("error(")) + .collect::>(); + assert_eq!(error_lines, ["error(0.26) D0"]); + assert!(!standard_text.contains("TP0")); + assert!(!standard_text.contains("TP1")); + + let (mechanisms, _coords) = dem.to_mechanisms(); + assert_eq!(mechanisms.len(), 1); + assert!((mechanisms[0].0 - 0.26).abs() < 1e-12); + assert_eq!(mechanisms[0].1, vec![0]); + assert!(mechanisms[0].2.is_empty()); + } + + #[test] + fn test_pecos_dem_preserves_effects_that_differ_by_tracked_ops() { + use pecos_core::pauli::{X, Z}; + + let mut dem = DetectorErrorModel::new(); + dem.add_detector(DetectorDef::new(0)); + dem.add_tracked_operator(DemOutput::new(0).with_pauli(X(0)).with_label("tracked_x0")); + dem.add_tracked_operator(DemOutput::new(1).with_pauli(Z(0)).with_label("tracked_z0")); + dem.add_direct_contribution( + FaultMechanism::from_unsorted_with_tracked_ops([0], [], [0]), + 0.1, + ); + dem.add_direct_contribution( + FaultMechanism::from_unsorted_with_tracked_ops([0], [], [1]), + 0.2, + ); + + let pecos_text = dem.to_pecos_string(); + let error_lines = pecos_text + .lines() + .filter(|line| line.starts_with("error(")) + .collect::>(); + assert_eq!(error_lines, ["error(0.1) D0 TP0", "error(0.2) D0 TP1"]); + assert!(pecos_text.contains(r#""label":"tracked_x0""#)); + assert!(pecos_text.contains(r#""label":"tracked_z0""#)); + } + + #[test] + fn test_standard_dem_serialization_never_shifts_observable_ids_for_tracked_ops() { + use pecos_core::pauli::{X, Z}; + + let mut dem = DetectorErrorModel::new(); + dem.add_detector(DetectorDef::new(0)); + dem.add_observable(DemOutput::new(0).with_records([-1]).with_label("L0")); + dem.add_observable(DemOutput::new(2).with_records([-2]).with_label("L2")); + dem.add_tracked_operator( + DemOutput::new(0) + .with_kind(DemOutputKind::TrackedOperator) + .with_pauli(X(0)) + .with_label("tracked_x0"), + ); + dem.add_tracked_operator( + DemOutput::new(1) + .with_kind(DemOutputKind::TrackedOperator) + .with_pauli(Z(3)) + .with_label("tracked_z3"), + ); + dem.add_direct_contribution( + FaultMechanism::from_unsorted_with_tracked_ops([0], [0, 2], [1]), + 0.01, + ); + + assert_eq!(dem.num_observables(), 3); + assert_eq!(dem.num_dem_outputs(), 3); + assert_eq!(dem.num_tracked_ops(), 2); + + let standard_text = dem.to_string(); + assert!(standard_text.contains("logical_observable L0")); + assert!(!standard_text.contains("logical_observable L1")); + assert!(standard_text.contains("logical_observable L2")); + assert!(!standard_text.contains("logical_observable L3")); + assert!(standard_text.contains("error(0.01) D0 L0 L2")); + assert!(!standard_text.contains("TP1")); + assert!(!standard_text.contains("pecos_observable")); + assert!(!standard_text.contains("pecos_tracked_op")); + + let pecos_text = dem.to_pecos_string(); + assert!(pecos_text.contains("error(0.01) D0 L0 L2 TP1")); + assert!(pecos_text.contains(r#""kind":"observable""#)); + assert!(pecos_text.contains(r#""kind":"tracked_operator""#)); + assert!(pecos_text.contains(r#""id":0"#)); + assert!(pecos_text.contains(r#""id":2"#)); + assert!(pecos_text.contains(r#""pauli":"+X0""#)); + assert!(pecos_text.contains(r#""pauli":"+Z3""#)); + + let recovered = DetectorErrorModel::new() + .with_pecos_dem_metadata(&pecos_text) + .unwrap(); + assert_eq!(recovered.num_dem_outputs(), 3); + assert_eq!(recovered.num_tracked_ops(), 2); + assert_eq!( + recovered + .dem_outputs() + .iter() + .map(|op| op.id) + .collect::>(), + [0, 2] + ); + assert_eq!( + recovered + .tracked_ops() + .iter() + .map(|op| op.id) + .collect::>(), + [0, 1] + ); + } + + #[test] + fn test_pecos_dem_text_metadata_round_trip_keeps_observable_and_tracked_id_spaces() { + use pecos_core::pauli::{X, Y, Z}; + + let mut dem = DetectorErrorModel::new(); + dem.add_detector(DetectorDef::new(0)); + dem.add_detector(DetectorDef::new(1)); + dem.add_observable(DemOutput::new(0).with_records([-1]).with_label("L0")); + dem.add_observable( + DemOutput::new(3) + .with_records([-2, -1]) + .with_label("logical_aux"), + ); + dem.add_tracked_operator( + DemOutput::new(0) + .with_pauli(X(0) & Z(2)) + .with_label("tracked_x0_z2"), + ); + dem.add_tracked_operator(DemOutput::new(2).with_pauli(Y(5)).with_label("tracked_y5")); + dem.add_direct_contribution( + FaultMechanism::from_unsorted_with_tracked_ops([0, 1], [3], [2]), + 0.125, + ); + + let standard_text = dem.to_string(); + assert!(standard_text.contains("logical_observable L0")); + assert!(!standard_text.contains("logical_observable L1")); + assert!(!standard_text.contains("logical_observable L2")); + assert!(standard_text.contains("logical_observable L3")); + assert!(standard_text.contains("error(0.125) D0 D1 L3")); + assert!(!standard_text.contains("TP2")); + assert!(!standard_text.contains("pecos_tracked_op")); + + let pecos_text = format!( + "# ordinary comments and standard DEM lines are allowed\n{}\n", + dem.to_pecos_string() + ); + let recovered = DetectorErrorModel::new() + .with_pecos_dem_metadata(&pecos_text) + .unwrap(); + assert_eq!(recovered.num_observables(), 4); + assert_eq!(recovered.num_dem_outputs(), 4); + assert_eq!(recovered.num_tracked_ops(), 3); + assert_eq!( + recovered + .dem_outputs() + .iter() + .map(|op| (op.id, op.label.as_deref())) + .collect::>(), + [(0, Some("L0")), (3, Some("logical_aux"))] + ); + assert_eq!( + recovered + .tracked_ops() + .iter() + .map(|op| (op.id, op.label.as_deref())) + .collect::>(), + [(0, Some("tracked_x0_z2")), (2, Some("tracked_y5"))] + ); + assert_eq!( + recovered.tracked_ops()[0] + .pauli + .as_ref() + .unwrap() + .to_sparse_str(), + "+X0 Z2" + ); + assert_eq!( + recovered.tracked_ops()[1] + .pauli + .as_ref() + .unwrap() + .to_sparse_str(), + "+Y5" + ); + + let reserialized = recovered.to_pecos_string(); + assert!(reserialized.contains("logical_observable L0")); + assert!(!reserialized.contains("logical_observable L1")); + assert!(!reserialized.contains("logical_observable L2")); + assert!(reserialized.contains("logical_observable L3")); + assert!(reserialized.contains(r#""kind":"observable""#)); + assert!(reserialized.contains(r#""kind":"tracked_operator""#)); + assert!(reserialized.contains(r#""pauli":"+X0 Z2""#)); + assert!(reserialized.contains(r#""pauli":"+Y5""#)); + assert!( + !reserialized.contains("TP2"), + "metadata-only recovery should not invent mechanism effects" + ); + } + + #[test] + fn test_pecos_dem_text_and_metadata_json_preserve_same_output_metadata() { + use crate::fault_tolerance::dem_builder::ParsedDem; + use pecos_core::pauli::{X, Y, Z}; + + let mut dem = DetectorErrorModel::new(); + dem.add_detector(DetectorDef::new(0).with_records([-1])); + dem.add_observable(DemOutput::new(0).with_records([-1]).with_label("L0")); + dem.add_observable(DemOutput::new(3).with_records([-2]).with_label("L3")); + dem.add_tracked_operator( + DemOutput::new(0) + .with_pauli(X(0) & Z(2)) + .with_label("tracked_x0_z2"), + ); + dem.add_tracked_operator(DemOutput::new(3).with_pauli(Y(5)).with_label("tracked_y5")); + dem.add_direct_contribution( + FaultMechanism::from_unsorted_with_tracked_ops([0], [3], [3]), + 0.125, + ); + + let json_recovered = DetectorErrorModel::new() + .with_pecos_metadata_json(&dem.to_pecos_metadata_json()) + .unwrap(); + let text_recovered = DetectorErrorModel::new() + .with_pecos_dem_metadata(&dem.to_pecos_string()) + .unwrap(); + + let source_json: serde_json::Value = + serde_json::from_str(&dem.to_pecos_metadata_json()).unwrap(); + let from_json: serde_json::Value = + serde_json::from_str(&json_recovered.to_pecos_metadata_json()).unwrap(); + let from_text: serde_json::Value = + serde_json::from_str(&text_recovered.to_pecos_metadata_json()).unwrap(); + + assert_eq!(from_json, source_json); + assert_eq!(from_text, source_json); + + let parsed: ParsedDem = dem.to_pecos_string().parse().unwrap(); + assert_eq!(parsed.num_dem_outputs(), 4); + assert_eq!(parsed.num_tracked_ops(), 4); + assert_eq!(parsed.mechanisms[0].format_targets(), "D0 L3 TP3"); + assert_eq!(parsed.mechanisms[0].components[0].observables, vec![3]); + assert_eq!(parsed.mechanisms[0].components[0].tracked_ops, vec![3]); + assert_eq!( + parsed.dem_outputs[0].as_ref().unwrap().label.as_deref(), + Some("L0") + ); + assert_eq!( + parsed.dem_outputs[3].as_ref().unwrap().label.as_deref(), + Some("L3") + ); + assert_eq!( + parsed.tracked_ops[0] + .as_ref() + .unwrap() + .pauli + .as_ref() + .unwrap() + .to_sparse_str(), + "+X0 Z2" + ); + assert_eq!( + parsed.tracked_ops[3].as_ref().unwrap().label.as_deref(), + Some("tracked_y5") + ); + } + #[test] fn test_pecos_dem_metadata_parser_rejects_malformed_extension_line() { let err = DetectorErrorModel::new() @@ -4403,13 +4919,14 @@ mod tests { #[test] fn test_decomposed_error_single() { - let mechanism = FaultMechanism::from_unsorted([0, 1], [0]); + let mechanism = FaultMechanism::from_unsorted_with_tracked_ops([0, 1], [0], [2]); let decomposed = DecomposedFault::single(mechanism.clone()); assert_eq!(decomposed.components.len(), 1); assert!(decomposed.is_graphlike()); assert_eq!(decomposed.full_effect(), mechanism); assert_eq!(decomposed.to_stim_targets(), "D0 D1 L0"); + assert_eq!(decomposed.to_pecos_targets(), "D0 D1 L0 TP2"); } #[test] diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index d32722163..6782754b4 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -3082,6 +3082,434 @@ mod tests { assert_case(GateType::SWAP, PauliString::z(1)); } + #[test] + fn test_catalog_all_two_qubit_cliffords_propagate_x_fault_measurement_support() { + fn apply_gate(tc: &mut TickCircuit, gate_type: GateType) { + match gate_type { + GateType::CX => { + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + } + GateType::CY => { + tc.tick().cy(&[(QubitId(0), QubitId(1))]); + } + GateType::CZ => { + tc.tick().cz(&[(QubitId(0), QubitId(1))]); + } + GateType::SXX => { + tc.tick().sxx(&[(QubitId(0), QubitId(1))]); + } + GateType::SXXdg => { + tc.tick().sxxdg(&[(QubitId(0), QubitId(1))]); + } + GateType::SYY => { + tc.tick().syy(&[(QubitId(0), QubitId(1))]); + } + GateType::SYYdg => { + tc.tick().syydg(&[(QubitId(0), QubitId(1))]); + } + GateType::SZZ => { + tc.tick().szz(&[(QubitId(0), QubitId(1))]); + } + GateType::SZZdg => { + tc.tick().szzdg(&[(QubitId(0), QubitId(1))]); + } + GateType::SWAP => { + tc.tick().swap(&[(QubitId(0), QubitId(1))]); + } + other => panic!("unexpected gate type {other:?}"), + } + } + + for (gate_type, expected_measurements) in [ + (GateType::CX, &[0usize, 1][..]), + (GateType::CY, &[0usize, 1][..]), + (GateType::CZ, &[0usize][..]), + (GateType::SXX, &[0usize][..]), + (GateType::SXXdg, &[0usize][..]), + (GateType::SYY, &[1usize][..]), + (GateType::SYYdg, &[1usize][..]), + (GateType::SZZ, &[0usize][..]), + (GateType::SZZdg, &[0usize][..]), + (GateType::SWAP, &[1usize][..]), + ] { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + apply_gate(&mut tc, gate_type); + tc.tick().mz(&[QubitId(0), QubitId(1)]); + + let catalog = build_fault_catalog( + &tc, + &StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + + let h_loc = catalog + .locations + .iter() + .find(|loc| loc.gate_type == GateType::H && loc.qubits.as_slice() == [0]) + .unwrap(); + let x_fault = h_loc + .faults + .iter() + .find(|fault| fault.pauli.as_ref() == Some(&PauliString::x(0))) + .unwrap(); + + assert_eq!( + x_fault.affected_measurements.as_slice(), + expected_measurements, + "{gate_type:?}" + ); + } + } + + #[test] + fn test_catalog_standard_cliffords_match_forward_pauli_oracle_for_all_alternatives() { + fn apply_single_gate(tc: &mut TickCircuit, gate_type: GateType) { + match gate_type { + GateType::X => { + tc.tick().x(&[QubitId(0)]); + } + GateType::Y => { + tc.tick().y(&[QubitId(0)]); + } + GateType::Z => { + tc.tick().z(&[QubitId(0)]); + } + GateType::H => { + tc.tick().h(&[QubitId(0)]); + } + GateType::SZ => { + tc.tick().sz(&[QubitId(0)]); + } + GateType::SZdg => { + tc.tick().szdg(&[QubitId(0)]); + } + GateType::SX => { + tc.tick().sx(&[QubitId(0)]); + } + GateType::SXdg => { + tc.tick().sxdg(&[QubitId(0)]); + } + GateType::SY => { + tc.tick().sy(&[QubitId(0)]); + } + GateType::SYdg => { + tc.tick().sydg(&[QubitId(0)]); + } + GateType::F => { + tc.tick().f(&[QubitId(0)]); + } + GateType::Fdg => { + tc.tick().fdg(&[QubitId(0)]); + } + other => panic!("unexpected single-qubit gate {other:?}"), + } + } + + fn apply_pair_gate(tc: &mut TickCircuit, gate_type: GateType) { + match gate_type { + GateType::CX => { + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + } + GateType::CY => { + tc.tick().cy(&[(QubitId(0), QubitId(1))]); + } + GateType::CZ => { + tc.tick().cz(&[(QubitId(0), QubitId(1))]); + } + GateType::SXX => { + tc.tick().sxx(&[(QubitId(0), QubitId(1))]); + } + GateType::SXXdg => { + tc.tick().sxxdg(&[(QubitId(0), QubitId(1))]); + } + GateType::SYY => { + tc.tick().syy(&[(QubitId(0), QubitId(1))]); + } + GateType::SYYdg => { + tc.tick().syydg(&[(QubitId(0), QubitId(1))]); + } + GateType::SZZ => { + tc.tick().szz(&[(QubitId(0), QubitId(1))]); + } + GateType::SZZdg => { + tc.tick().szzdg(&[(QubitId(0), QubitId(1))]); + } + GateType::SWAP => { + tc.tick().swap(&[(QubitId(0), QubitId(1))]); + } + other => panic!("unexpected two-qubit gate {other:?}"), + } + } + + fn pauli_type(pauli: Pauli) -> PauliType { + match pauli { + Pauli::X => PauliType::X, + Pauli::Y => PauliType::Y, + Pauli::Z => PauliType::Z, + Pauli::I => panic!("identity is not a fault alternative"), + } + } + + fn expected_effect( + pauli: &PauliString, + start: usize, + gates: &[GateLoc], + meas_positions: &HashMap, + tracked_ops: &[PauliString], + ) -> PropagatedFaultEffect { + let terms: Vec<_> = pauli + .iter_pairs() + .map(|(p, q)| (pauli_type(p), q.index())) + .collect(); + match terms.as_slice() { + [(p, q)] => { + propagate_single_effect(*p, *q, start, gates, meas_positions, tracked_ops) + } + [(p0, q0), (p1, q1)] => propagate_pair_effect( + [(*p0, *q0), (*p1, *q1)], + start, + gates, + meas_positions, + tracked_ops, + ), + other => panic!("expected one- or two-qubit Pauli alternative, got {other:?}"), + } + } + + for gate_type in STANDARD_1Q_CLIFFORD_GATES { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + apply_single_gate(&mut tc, *gate_type); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String(tc.num_measurements().to_string()), + ); + tc.add_detector_metadata(&[-1], None, Some("D0"), Some(0)) + .unwrap(); + tc.add_observable_metadata(&[-1], Some(0), Some("L0")) + .unwrap(); + tc.tracked_operator_labeled("tracked_x1", PauliString::x(1)); + tc.tracked_operator_labeled("tracked_y1", PauliString::y(1)); + tc.tracked_operator_labeled("tracked_z1", PauliString::z(1)); + + let (gates, meas_positions) = flatten_tick_circuit(&tc); + let tracked_ops = parse_tracked_operator_annotations(&tc); + let catalog = build_fault_catalog( + &tc, + &StochasticNoiseParams { + p1: 0.03, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + let source_loc_idx = gates + .iter() + .position(|loc| loc.gate_type == GateType::H && loc.qubits.as_slice() == [0]) + .unwrap(); + let source_loc = catalog + .locations + .iter() + .find(|loc| { + loc.tick == gates[source_loc_idx].tick + && loc.gate_index == gates[source_loc_idx].gate_index + }) + .unwrap(); + + for fault in &source_loc.faults { + let pauli = fault.pauli.as_ref().unwrap(); + let effect = expected_effect( + pauli, + source_loc_idx + 1, + &gates, + &meas_positions, + &tracked_ops, + ); + let measurements: Vec<_> = effect.affected_measurements.iter().copied().collect(); + assert_eq!( + fault.affected_measurements, measurements, + "{gate_type:?} {pauli:?}" + ); + assert_eq!( + fault.affected_detectors, measurements, + "{gate_type:?} {pauli:?}" + ); + assert_eq!( + fault.affected_observables, measurements, + "{gate_type:?} {pauli:?}" + ); + assert_eq!( + fault.affected_tracked_ops, effect.affected_tracked_ops, + "{gate_type:?} {pauli:?}" + ); + } + } + + for gate_type in STANDARD_2Q_CLIFFORD_GATES { + let mut tc = TickCircuit::new(); + tc.tick().cx(&[(QubitId(0), QubitId(1))]); + apply_pair_gate(&mut tc, *gate_type); + tc.tick() + .cx(&[(QubitId(0), QubitId(2)), (QubitId(1), QubitId(3))]); + tc.tick().mz(&[QubitId(0), QubitId(1)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String(tc.num_measurements().to_string()), + ); + tc.add_detector_metadata(&[-2], None, Some("D0"), Some(0)) + .unwrap(); + tc.add_detector_metadata(&[-1], None, Some("D1"), Some(1)) + .unwrap(); + tc.add_observable_metadata(&[-2], Some(0), Some("L0")) + .unwrap(); + tc.add_observable_metadata(&[-1], Some(1), Some("L1")) + .unwrap(); + tc.tracked_operator_labeled("tracked_x2", PauliString::x(2)); + tc.tracked_operator_labeled("tracked_y2", PauliString::y(2)); + tc.tracked_operator_labeled("tracked_z2", PauliString::z(2)); + tc.tracked_operator_labeled("tracked_x3", PauliString::x(3)); + tc.tracked_operator_labeled("tracked_y3", PauliString::y(3)); + tc.tracked_operator_labeled("tracked_z3", PauliString::z(3)); + + let (gates, meas_positions) = flatten_tick_circuit(&tc); + let tracked_ops = parse_tracked_operator_annotations(&tc); + let catalog = build_fault_catalog( + &tc, + &StochasticNoiseParams { + p1: 0.0, + p2: 0.03, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + let source_loc_idx = gates + .iter() + .position(|loc| loc.gate_type == GateType::CX && loc.qubits.as_slice() == [0, 1]) + .unwrap(); + let source_loc = catalog + .locations + .iter() + .find(|loc| { + loc.tick == gates[source_loc_idx].tick + && loc.gate_index == gates[source_loc_idx].gate_index + }) + .unwrap(); + + for fault in &source_loc.faults { + let pauli = fault.pauli.as_ref().unwrap(); + let effect = expected_effect( + pauli, + source_loc_idx + 1, + &gates, + &meas_positions, + &tracked_ops, + ); + let measurements: Vec<_> = effect.affected_measurements.iter().copied().collect(); + assert_eq!( + fault.affected_measurements, measurements, + "{gate_type:?} {pauli:?}" + ); + assert_eq!( + fault.affected_detectors, measurements, + "{gate_type:?} {pauli:?}" + ); + assert_eq!( + fault.affected_observables, measurements, + "{gate_type:?} {pauli:?}" + ); + assert_eq!( + fault.affected_tracked_ops, effect.affected_tracked_ops, + "{gate_type:?} {pauli:?}" + ); + } + } + } + + #[test] + fn test_fault_configurations_xor_detectors_observables_and_tracked_ops_separately() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0), QubitId(1)]); + tc.tick().cx(&[(QubitId(0), QubitId(2))]); + tc.tick().mz(&[QubitId(0), QubitId(1)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String(tc.num_measurements().to_string()), + ); + tc.add_detector_metadata(&[-2, -1], None, Some("D0"), Some(0)) + .unwrap(); + tc.add_observable_metadata(&[-2], Some(0), Some("L0")) + .unwrap(); + tc.tracked_operator_labeled("tracked_z2", PauliString::z(2)); + + let catalog = build_fault_catalog( + &tc, + &StochasticNoiseParams { + p1: 1.0, + p2: 0.0, + p_meas: 0.0, + p_prep: 0.0, + }, + ) + .unwrap(); + let h0 = catalog + .locations + .iter() + .position(|loc| loc.gate_type == GateType::H && loc.qubits.as_slice() == [0]) + .unwrap(); + let h1 = catalog + .locations + .iter() + .position(|loc| loc.gate_type == GateType::H && loc.qubits.as_slice() == [1]) + .unwrap(); + let x0 = catalog.locations[h0] + .faults + .iter() + .position(|fault| fault.pauli.as_ref() == Some(&PauliString::x(0))) + .unwrap(); + let x1 = catalog.locations[h1] + .faults + .iter() + .position(|fault| fault.pauli.as_ref() == Some(&PauliString::x(1))) + .unwrap(); + + let config = catalog + .fault_configurations(2) + .find(|config| { + config.location_indices == [h0, h1] && config.alternative_indices == [x0, x1] + }) + .unwrap(); + + assert_eq!(catalog.locations[h0].faults[x0].affected_detectors, [0]); + assert_eq!(catalog.locations[h0].faults[x0].affected_observables, [0]); + assert_eq!(catalog.locations[h0].faults[x0].affected_tracked_ops, [0]); + assert_eq!(catalog.locations[h1].faults[x1].affected_detectors, [0]); + assert!( + catalog.locations[h1].faults[x1] + .affected_observables + .is_empty() + ); + assert!( + catalog.locations[h1].faults[x1] + .affected_tracked_ops + .is_empty() + ); + + assert_eq!(config.affected_measurements, [0, 1]); + assert!(config.affected_detectors.is_empty()); + assert_eq!(config.affected_observables, [0]); + assert_eq!(config.affected_tracked_ops, [0]); + } + #[test] fn test_tracked_operator_phase_is_ignored_for_flip_tracking() { let mut tc = TickCircuit::new(); @@ -3320,6 +3748,46 @@ mod tests { assert_eq!(mechanisms, build_fault_table(&tc, &noise).unwrap()); } + #[test] + fn test_fault_configurations_skip_zero_probability_fault_events() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.tick().mz(&[QubitId(0)]); + tc.set_meta( + "num_measurements", + pecos_quantum::Attribute::String("1".to_string()), + ); + + let catalog = FaultCatalog::from_circuit(&tc).unwrap(); + assert_eq!(catalog.fault_configurations(0).count(), 1); + assert_eq!( + catalog.fault_configurations(1).count(), + 0, + "unparameterized structural catalogs should not yield zero-probability selected faults" + ); + + let mut parameterized = catalog.clone(); + parameterized.with_noise(&StochasticNoiseParams { + p1: 0.0, + p2: 0.0, + p_meas: 0.02, + p_prep: 0.0, + }); + assert_eq!( + parameterized.fault_configurations(1).count(), + 1, + "only the nonzero measurement fault location should be yielded" + ); + assert_eq!( + parameterized + .fault_configurations(1) + .next() + .unwrap() + .location_indices, + vec![1] + ); + } + #[test] fn test_tracked_only_effect_stays_in_catalog_but_not_raw_mechanisms() { let mut tc = TickCircuit::new(); diff --git a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs index 0df2b2e70..b7af4b999 100644 --- a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs +++ b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs @@ -430,6 +430,63 @@ mod tests { assert!((result.logical_weights[&vec![]] - (0.1 / 0.9)).abs() < 1e-12); } + #[test] + fn test_decode_ignores_tracked_operator_effects() { + let catalog = FaultCatalog { + locations: vec![ + FaultLocation { + tick: 0, + gate_index: 0, + gate_type: GateType::H, + qubits: vec![0], + channel: crate::fault_tolerance::fault_sampler::FaultChannel::P1, + channel_probability: 0.2, + no_fault_probability: 0.8, + num_alternatives: 1, + faults: vec![FaultAlternative { + kind: FaultKind::Pauli, + pauli: None, + affected_measurements: Vec::new(), + affected_detectors: vec![0], + affected_observables: vec![1], + affected_tracked_ops: vec![0], + conditional_probability: 1.0, + absolute_probability: 0.2, + }], + }, + FaultLocation { + tick: 1, + gate_index: 0, + gate_type: GateType::H, + qubits: vec![1], + channel: crate::fault_tolerance::fault_sampler::FaultChannel::P1, + channel_probability: 0.1, + no_fault_probability: 0.9, + num_alternatives: 1, + faults: vec![FaultAlternative { + kind: FaultKind::Pauli, + pauli: None, + affected_measurements: Vec::new(), + affected_detectors: vec![0], + affected_observables: Vec::new(), + affected_tracked_ops: vec![3], + conditional_probability: 1.0, + absolute_probability: 0.1, + }], + }, + ], + }; + + let result = TargetedLookupDecoder::new(&catalog) + .max_faults(1) + .decode(&[0]); + + assert_eq!(result.best_logical, vec![1]); + assert_eq!(result.logical_weights.len(), 2); + assert!((result.logical_weights[&vec![1]] - (0.2 / 0.8)).abs() < 1e-12); + assert!((result.logical_weights[&vec![]] - (0.1 / 0.9)).abs() < 1e-12); + } + #[test] fn test_unexplainable_syndrome_returns_empty_weights() { let mut tc = TickCircuit::new(); diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index b960b700f..c07dd6515 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -4146,6 +4146,379 @@ mod tests { } } + #[test] + fn test_all_standard_gate_families_round_trip_through_dag() { + use pecos_core::pauli::{X, Z}; + + fn channel_payloads(circuit: &TickCircuit) -> Vec { + circuit + .iter_gates() + .filter_map(|gate| gate.channel.clone()) + .collect() + } + + fn nonzero_gate_counts( + circuit: &TickCircuit, + ) -> std::collections::BTreeMap { + circuit + .gate_counts_by_type() + .into_iter() + .filter(|(_, count)| *count > 0) + .collect() + } + + let mut tc1 = TickCircuit::new(); + tc1.tick() + .x(&[0]) + .y(&[1]) + .z(&[2]) + .h(&[3]) + .sx(&[4]) + .sxdg(&[5]) + .sy(&[6]) + .sydg(&[7]) + .sz(&[8]) + .szdg(&[9]) + .f(&[10]) + .fdg(&[11]) + .iden(&[12]); + tc1.tick() + .cx(&[(20, 21)]) + .cy(&[(22, 23)]) + .cz(&[(24, 25)]) + .sxx(&[(26, 27)]) + .sxxdg(&[(28, 29)]) + .syy(&[(30, 31)]) + .syydg(&[(32, 33)]) + .szz(&[(34, 35)]) + .szzdg(&[(36, 37)]) + .swap(&[(38, 39)]); + tc1.tick() + .rx(Angle64::from_turns(0.125), &[40]) + .ry(Angle64::from_turns(0.25), &[41]) + .rz(Angle64::from_turns(0.375), &[42]) + .r1xy(Angle64::from_turns(0.125), Angle64::from_turns(0.25), &[43]) + .u( + Angle64::from_turns(0.125), + Angle64::from_turns(0.25), + Angle64::from_turns(0.375), + &[44], + ); + tc1.tick() + .channel(pecos_core::channel::Depolarizing(0.01, 50)); + tc1.tick() + .channel(pecos_core::channel::Depolarizing2(0.02, 51, 52)); + tc1.tick().idle(3u64, &[60]); + tc1.tick().pz(&[70, 71]); + let ms = tc1.tick().mz(&[70, 71]); + tc1.detector_labeled("det-all-gates", &[ms[0]]); + tc1.observable_labeled("obs-all-gates", &[ms[1]]); + tc1.tracked_operator_labeled("tracked-all-gates", X(70) & Z(71)); + + let tc2 = TickCircuit::from(&DagCircuit::from(&tc1)); + + assert_eq!(tc2.gate_count(), tc1.gate_count()); + assert_eq!(tc2.num_measurements(), tc1.num_measurements()); + assert_eq!(nonzero_gate_counts(&tc2), nonzero_gate_counts(&tc1)); + assert_eq!(channel_payloads(&tc2), channel_payloads(&tc1)); + assert_eq!(tc2.annotations().len(), tc1.annotations().len()); + assert_eq!( + tc2.annotations() + .iter() + .map(|ann| ann.label.as_deref()) + .collect::>(), + tc1.annotations() + .iter() + .map(|ann| ann.label.as_deref()) + .collect::>() + ); + assert!(matches!( + tc2.annotations()[0].kind, + AnnotationKind::Detector { .. } + )); + assert!(matches!( + tc2.annotations()[1].kind, + AnnotationKind::Observable { .. } + )); + assert!(matches!( + tc2.annotations()[2].kind, + AnnotationKind::TrackedOperator + )); + assert!(tc2.has_channel_operations()); + } + + #[test] + fn test_seeded_mixed_standard_gate_round_trip_preserves_metadata_annotations_and_batches() { + use pecos_core::pauli::{X, Y, Z}; + + fn apply_single(tick: &mut TickHandle<'_>, gate_type: GateType, qubit: usize) { + match gate_type { + GateType::X => { + tick.x(&[qubit]); + } + GateType::Y => { + tick.y(&[qubit]); + } + GateType::Z => { + tick.z(&[qubit]); + } + GateType::H => { + tick.h(&[qubit]); + } + GateType::SZ => { + tick.sz(&[qubit]); + } + GateType::SZdg => { + tick.szdg(&[qubit]); + } + GateType::SX => { + tick.sx(&[qubit]); + } + GateType::SXdg => { + tick.sxdg(&[qubit]); + } + GateType::SY => { + tick.sy(&[qubit]); + } + GateType::SYdg => { + tick.sydg(&[qubit]); + } + GateType::F => { + tick.f(&[qubit]); + } + GateType::Fdg => { + tick.fdg(&[qubit]); + } + other => panic!("unexpected single-qubit gate {other:?}"), + } + } + + fn apply_pair(tick: &mut TickHandle<'_>, gate_type: GateType, a: usize, b: usize) { + match gate_type { + GateType::CX => { + tick.cx(&[(a, b)]); + } + GateType::CY => { + tick.cy(&[(a, b)]); + } + GateType::CZ => { + tick.cz(&[(a, b)]); + } + GateType::SXX => { + tick.sxx(&[(a, b)]); + } + GateType::SXXdg => { + tick.sxxdg(&[(a, b)]); + } + GateType::SYY => { + tick.syy(&[(a, b)]); + } + GateType::SYYdg => { + tick.syydg(&[(a, b)]); + } + GateType::SZZ => { + tick.szz(&[(a, b)]); + } + GateType::SZZdg => { + tick.szzdg(&[(a, b)]); + } + GateType::SWAP => { + tick.swap(&[(a, b)]); + } + other => panic!("unexpected two-qubit gate {other:?}"), + } + } + + fn nonzero_gate_counts( + circuit: &TickCircuit, + ) -> std::collections::BTreeMap { + circuit + .gate_counts_by_type() + .into_iter() + .filter(|(_, count)| *count > 0) + .collect() + } + + fn choose_gate(gates: &[GateType], state: u64, shift: u32) -> GateType { + let len = u64::try_from(gates.len()).unwrap(); + let idx = usize::try_from((state >> shift) % len).unwrap(); + gates[idx] + } + + const ONE_Q: &[GateType] = &[ + GateType::X, + GateType::Y, + GateType::Z, + GateType::H, + GateType::SZ, + GateType::SZdg, + GateType::SX, + GateType::SXdg, + GateType::SY, + GateType::SYdg, + GateType::F, + GateType::Fdg, + ]; + const TWO_Q: &[GateType] = &[ + GateType::CX, + GateType::CY, + GateType::CZ, + GateType::SXX, + GateType::SXXdg, + GateType::SYY, + GateType::SYYdg, + GateType::SZZ, + GateType::SZZdg, + GateType::SWAP, + ]; + + let mut state = 0xdecaf_bad5eed_u64; + for case_idx in 0..10usize { + state = state + .wrapping_mul(6_364_136_223_846_793_005) + .wrapping_add(1_442_695_040_888_963_407); + let base = 100 * case_idx; + let one_a = choose_gate(ONE_Q, state, 0); + let one_b = choose_gate(ONE_Q, state, 8); + let two = choose_gate(TWO_Q, state, 16); + let rz_bucket = u8::try_from((state >> 24) & 3).unwrap(); + let rz_turns = f64::from(rz_bucket + 1) / 8.0; + + let mut tc1 = TickCircuit::new(); + tc1.set_meta("case", Attribute::Int(i64::try_from(case_idx).unwrap())); + { + let mut tick = tc1.tick(); + tick.meta("round", Attribute::Int(0)) + .meta("kind", Attribute::String("single".into())); + apply_single(&mut tick, one_a, base); + apply_single(&mut tick, one_b, base + 1); + } + { + let mut tick = tc1.tick(); + tick.meta("round", Attribute::Int(1)) + .meta("kind", Attribute::String("mixed".into())); + apply_pair(&mut tick, two, base + 2, base + 3); + tick.rz(Angle64::from_turns(rz_turns), &[base + 4]) + .rx(Angle64::from_turns(0.25), &[base + 5]); + } + tc1.tick() + .meta("round", Attribute::Int(2)) + .channel(pecos_core::channel::Depolarizing(0.01, base + 6)); + tc1.tick().pz(&[base, base + 1, base + 2]); + let measurements = tc1.tick().mz(&[base, base + 1, base + 2]); + tc1.detector_labeled( + &format!("det-{case_idx}"), + &[measurements[0], measurements[2]], + ); + tc1.observable_labeled(&format!("obs-{case_idx}"), &[measurements[1]]); + let tracked = if state & (1 << 32) == 0 { + X(base) & Z(base + 3) + } else { + Y(base + 2) + }; + tc1.tracked_operator_labeled(&format!("tracked-{case_idx}"), tracked.clone()); + + let tc2 = TickCircuit::from(&DagCircuit::from(&tc1)); + + assert_eq!( + tc2.get_meta("case"), + tc1.get_meta("case"), + "case {case_idx}" + ); + assert_eq!(tc2.gate_count(), tc1.gate_count(), "case {case_idx}"); + assert_eq!( + tc2.num_measurements(), + tc1.num_measurements(), + "case {case_idx}" + ); + assert_eq!( + nonzero_gate_counts(&tc2), + nonzero_gate_counts(&tc1), + "case {case_idx}" + ); + assert_eq!(tc2.annotations().len(), 3, "case {case_idx}"); + assert_eq!( + tc2.annotations() + .iter() + .map(|ann| ann.label.as_deref()) + .collect::>(), + tc1.annotations() + .iter() + .map(|ann| ann.label.as_deref()) + .collect::>(), + "case {case_idx}" + ); + assert!(matches!( + tc2.annotations()[0].kind, + AnnotationKind::Detector { .. } + )); + assert!(matches!( + tc2.annotations()[1].kind, + AnnotationKind::Observable { .. } + )); + assert!(matches!( + tc2.annotations()[2].kind, + AnnotationKind::TrackedOperator + )); + assert_eq!(tc2.annotations()[2].pauli, tracked, "case {case_idx}"); + assert!(tc2.has_channel_operations(), "case {case_idx}"); + } + } + + #[test] + fn test_batching_invariants_cover_parameters_channels_and_measurements() { + let same_rz = Gate::rz(Angle64::from_turns(0.25), &[0]); + let same_rz_disjoint = Gate::rz(Angle64::from_turns(0.25), &[1]); + let different_rz = Gate::rz(Angle64::from_turns(0.5), &[2]); + assert!(same_rz.can_batch_with(&same_rz_disjoint)); + assert!(!same_rz.can_batch_with(&different_rz)); + + let channel0 = Gate::channel(pecos_core::channel::Depolarizing(0.01, 10)); + let channel1 = Gate::channel(pecos_core::channel::Depolarizing(0.01, 11)); + assert!(!channel0.can_batch_with(&channel1)); + + let mut tick = Tick::new(); + tick.add_gate(same_rz); + tick.add_gate(same_rz_disjoint); + tick.merge_compatible_gate_at(1); + tick.add_gate(different_rz); + tick.add_gate(channel0); + tick.add_gate(channel1); + + assert_eq!(tick.gate_count(), 5); + assert_eq!(tick.gate_batch_count(), 4); + assert_eq!( + tick.gates()[0].qubits.as_slice(), + &[QubitId::from(0), QubitId::from(1)] + ); + assert!(tick.gates()[2].is_channel()); + assert!(tick.gates()[3].is_channel()); + + let mut meas = TickCircuit::new(); + meas.reserve_ticks(1); + let refs0 = meas.tick_at(0).mz(&[0, 1]); + meas.get_tick_mut(0).unwrap().set_gate_attr( + refs0[0].gate_idx, + "readout_family", + Attribute::String("fast".into()), + ); + let refs2 = meas.tick_at(0).mz(&[2]); + let tick = meas.get_tick_mut(0).unwrap(); + tick.set_gate_attr( + refs2[0].gate_idx, + "readout_family", + Attribute::String("slow".into()), + ); + tick.merge_compatible_gate_at(refs2[0].gate_idx); + + let tick = meas.get_tick(0).unwrap(); + assert_eq!(tick.len(), 2); + assert_eq!(tick.gate_count(), 3); + assert_eq!(tick.gate_batch_count(), 2); + assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)]); + assert_eq!(tick.gates()[1].meas_ids.as_slice(), &[MeasId(2)]); + } + #[test] fn test_tick_attrs_preserved_in_conversion() { let mut tc1 = TickCircuit::new(); diff --git a/crates/pecos-simulators/src/bitmask_pauli_prop.rs b/crates/pecos-simulators/src/bitmask_pauli_prop.rs index 563eff419..539cd845d 100644 --- a/crates/pecos-simulators/src/bitmask_pauli_prop.rs +++ b/crates/pecos-simulators/src/bitmask_pauli_prop.rs @@ -499,6 +499,28 @@ mod tests { } } + fn assert_phase_free_1q_table(name: &str, mut apply: F, table: &[(&str, &str)]) + where + F: FnMut(&mut BitmaskPauliProp), + { + for &(input, expected) in table { + let mut prop = bitmask_prop_from_dense(input); + apply(&mut prop); + assert_eq!(prop.dense_string(), expected, "{name}: {input}"); + } + } + + fn assert_phase_free_2q_table(name: &str, mut apply: F, table: &[(&str, &str)]) + where + F: FnMut(&mut BitmaskPauliProp), + { + for &(input, expected) in table { + let mut prop = bitmask_prop_from_dense(input); + apply(&mut prop); + assert_eq!(prop.dense_string(), expected, "{name}: {input}"); + } + } + #[test] fn single_qubit_cliffords_match_sparse_pauli_prop() { assert_matches_sparse_1q( @@ -584,6 +606,229 @@ mod tests { ); } + #[test] + fn standard_cliffords_match_phase_free_pauli_tables() { + const PAULI_SELF: &[(&str, &str)] = &[("I", "I"), ("X", "X"), ("Y", "Y"), ("Z", "Z")]; + const H_SY: &[(&str, &str)] = &[("I", "I"), ("X", "Z"), ("Y", "Y"), ("Z", "X")]; + const SZ: &[(&str, &str)] = &[("I", "I"), ("X", "Y"), ("Y", "X"), ("Z", "Z")]; + const SX: &[(&str, &str)] = &[("I", "I"), ("X", "X"), ("Y", "Z"), ("Z", "Y")]; + const F: &[(&str, &str)] = &[("I", "I"), ("X", "Y"), ("Y", "Z"), ("Z", "X")]; + const FDG: &[(&str, &str)] = &[("I", "I"), ("X", "Z"), ("Y", "X"), ("Z", "Y")]; + const CX: &[(&str, &str)] = &[ + ("XI", "XX"), + ("YI", "YX"), + ("ZI", "ZI"), + ("IX", "IX"), + ("IY", "ZY"), + ("IZ", "ZZ"), + ]; + const CY: &[(&str, &str)] = &[ + ("XI", "XY"), + ("YI", "YY"), + ("ZI", "ZI"), + ("IX", "ZX"), + ("IY", "IY"), + ("IZ", "ZZ"), + ]; + const CZ: &[(&str, &str)] = &[ + ("XI", "XZ"), + ("YI", "YZ"), + ("ZI", "ZI"), + ("IX", "ZX"), + ("IY", "ZY"), + ("IZ", "IZ"), + ]; + const SXX: &[(&str, &str)] = &[ + ("XI", "XI"), + ("YI", "ZX"), + ("ZI", "YX"), + ("IX", "IX"), + ("IY", "XZ"), + ("IZ", "XY"), + ]; + const SYY: &[(&str, &str)] = &[ + ("XI", "ZY"), + ("YI", "YI"), + ("ZI", "XY"), + ("IX", "YZ"), + ("IY", "IY"), + ("IZ", "YX"), + ]; + const SZZ: &[(&str, &str)] = &[ + ("XI", "YZ"), + ("YI", "XZ"), + ("ZI", "ZI"), + ("IX", "ZY"), + ("IY", "ZX"), + ("IZ", "IZ"), + ]; + const SWAP: &[(&str, &str)] = &[ + ("XI", "IX"), + ("YI", "IY"), + ("ZI", "IZ"), + ("IX", "XI"), + ("IY", "YI"), + ("IZ", "ZI"), + ]; + + assert_phase_free_1q_table( + "X", + |p| { + p.x(&[QubitId(0)]); + }, + PAULI_SELF, + ); + assert_phase_free_1q_table( + "Y", + |p| { + p.y(&[QubitId(0)]); + }, + PAULI_SELF, + ); + assert_phase_free_1q_table( + "Z", + |p| { + p.z(&[QubitId(0)]); + }, + PAULI_SELF, + ); + assert_phase_free_1q_table( + "H", + |p| { + p.h(&[QubitId(0)]); + }, + H_SY, + ); + assert_phase_free_1q_table( + "SZ", + |p| { + p.sz(&[QubitId(0)]); + }, + SZ, + ); + assert_phase_free_1q_table( + "SZdg", + |p| { + p.szdg(&[QubitId(0)]); + }, + SZ, + ); + assert_phase_free_1q_table( + "SX", + |p| { + p.sx(&[QubitId(0)]); + }, + SX, + ); + assert_phase_free_1q_table( + "SXdg", + |p| { + p.sxdg(&[QubitId(0)]); + }, + SX, + ); + assert_phase_free_1q_table( + "SY", + |p| { + p.sy(&[QubitId(0)]); + }, + H_SY, + ); + assert_phase_free_1q_table( + "SYdg", + |p| { + p.sydg(&[QubitId(0)]); + }, + H_SY, + ); + assert_phase_free_1q_table( + "F", + |p| { + p.f(&[QubitId(0)]); + }, + F, + ); + assert_phase_free_1q_table( + "Fdg", + |p| { + p.fdg(&[QubitId(0)]); + }, + FDG, + ); + + let pair = [(QubitId(0), QubitId(1))]; + assert_phase_free_2q_table( + "CX", + |p| { + p.cx(&pair); + }, + CX, + ); + assert_phase_free_2q_table( + "CY", + |p| { + p.cy(&pair); + }, + CY, + ); + assert_phase_free_2q_table( + "CZ", + |p| { + p.cz(&pair); + }, + CZ, + ); + assert_phase_free_2q_table( + "SXX", + |p| { + p.sxx(&pair); + }, + SXX, + ); + assert_phase_free_2q_table( + "SXXdg", + |p| { + p.sxxdg(&pair); + }, + SXX, + ); + assert_phase_free_2q_table( + "SYY", + |p| { + p.syy(&pair); + }, + SYY, + ); + assert_phase_free_2q_table( + "SYYdg", + |p| { + p.syydg(&pair); + }, + SYY, + ); + assert_phase_free_2q_table( + "SZZ", + |p| { + p.szz(&pair); + }, + SZZ, + ); + assert_phase_free_2q_table( + "SZZdg", + |p| { + p.szzdg(&pair); + }, + SZZ, + ); + assert_phase_free_2q_table( + "SWAP", + |p| { + p.swap(&pair); + }, + SWAP, + ); + } + #[test] fn two_qubit_cliffords_match_sparse_pauli_prop() { assert_matches_sparse_2q( diff --git a/exp/pecos-lindblad/tests/four_qubit_smoke.rs b/exp/pecos-lindblad/tests/four_qubit_smoke.rs index 5fcbed35c..823508476 100644 --- a/exp/pecos-lindblad/tests/four_qubit_smoke.rs +++ b/exp/pecos-lindblad/tests/four_qubit_smoke.rs @@ -39,6 +39,74 @@ fn kron_all(ops: &[&Matrix]) -> Matrix { } #[test] +fn three_qubit_identity_ad_on_one_qubit_fast_smoke() { + let d = 8; + let i2 = matrix::identity(2); + let sm = matrix::sigma_minus(); + let z = matrix::pauli_1q(Pauli1::Z); + + let beta_down = 1e-3; + let beta_phi = 2e-3; + let tau_g = 5.0; + + let sm_q1 = kron_all(&[&i2, &sm, &i2]); + let z_q1 = kron_all(&[&i2, &z, &i2]); + + let collapse: Vec<(Matrix, f64)> = vec![(sm_q1, beta_down), (z_q1, beta_phi / 2.0)]; + let hamiltonian: Matrix = vec![Complex64::new(0.0, 0.0); d * d]; + let noise = Lindbladian::new(d, hamiltonian, collapse); + + let gate = Gate::identity(3, noise, tau_g); + let pl = synthesize_numerical(&gate, DEFAULT_N_STEPS); + let pl_coarse = synthesize_numerical(&gate, 2); + + let rate = |s: &str| pl.rate(&PauliString::from_label(s).unwrap()); + assert_abs_diff_eq!(rate("IXI"), beta_down * tau_g / 4.0, epsilon = 1e-10); + assert_abs_diff_eq!(rate("IYI"), beta_down * tau_g / 4.0, epsilon = 1e-10); + assert_abs_diff_eq!(rate("IZI"), beta_phi * tau_g / 2.0, epsilon = 1e-10); + for ps in PauliString::enumerate_nonidentity(3) { + assert_abs_diff_eq!(pl.rate(&ps), pl_coarse.rate(&ps), epsilon = 1e-14); + } + + for ps in PauliString::enumerate_nonidentity(3) { + let label = format!("{}", ps); + if label == "IXI" || label == "IYI" || label == "IZI" { + continue; + } + assert_abs_diff_eq!(pl.rate(&ps), 0.0, epsilon = 1e-10); + } +} + +#[test] +fn three_qubit_identity_coherent_zzz_fast_smoke() { + let d = 8; + let tau_g = 5.0; + let delta = 1e-4; + + let z = matrix::pauli_1q(Pauli1::Z); + let zzz = kron_all(&[&z, &z, &z]); + let h_delta = matrix::scale(&zzz, Complex64::new(delta / 2.0, 0.0)); + let noise = Lindbladian::new(d, h_delta, Vec::new()); + let gate = Gate::identity(3, noise, tau_g); + let pl = synthesize_exact_unitary(&gate); + + let expected = (delta * tau_g).powi(2) / 4.0; + assert_abs_diff_eq!( + pl.rate(&PauliString::from_label("ZZZ").unwrap()), + expected, + epsilon = 1e-10 + ); + + for ps in PauliString::enumerate_nonidentity(3) { + if format!("{}", ps) == "ZZZ" { + continue; + } + assert_abs_diff_eq!(pl.rate(&ps), 0.0, epsilon = 1e-10); + } +} + +#[test] +#[ignore = "Slow 4Q validation; run explicitly with: cargo test -p pecos-lindblad --test four_qubit_smoke -- --ignored"] fn four_qubit_identity_ad_on_one_qubit() { let d = 16; let i2 = matrix::identity(2); @@ -84,6 +152,7 @@ fn four_qubit_identity_ad_on_one_qubit() { } #[test] +#[ignore = "Slow 4Q validation; run explicitly with: cargo test -p pecos-lindblad --test four_qubit_smoke -- --ignored"] fn four_qubit_identity_coherent_zzzz_smoke() { // 4Q identity with coherent ZZZZ noise -- since all Zs commute, each // lambda_{all-Z} should be non-zero, everything else zero. diff --git a/python/pecos-rslib/src/fault_tolerance_bindings.rs b/python/pecos-rslib/src/fault_tolerance_bindings.rs index aac4195a1..f90ecedda 100644 --- a/python/pecos-rslib/src/fault_tolerance_bindings.rs +++ b/python/pecos-rslib/src/fault_tolerance_bindings.rs @@ -3370,6 +3370,50 @@ impl PyDemSampler { self.inner.sample_batch(num_shots, &mut rng) } + /// Sample direct tracked-operator flips. + /// + /// Raises: + /// RuntimeError: If this sampler carries tracked operators but the + /// backend cannot evaluate tracked-operator flips directly. + #[pyo3(signature = (seed=None))] + fn sample_tracked_ops(&self, seed: Option) -> PyResult> { + use pecos_random::PecosRng; + use rand::RngExt; + + let mut rng = match seed { + Some(s) => PecosRng::seed_from_u64(s), + None => PecosRng::seed_from_u64(rand::rng().random()), + }; + + self.inner + .sample_tracked_operator_flips(&mut rng) + .map_err(|e| PyErr::new::(e.to_string())) + } + + /// Sample direct tracked-operator flips for multiple shots. + /// + /// Raises: + /// RuntimeError: If this sampler carries tracked operators but the + /// backend cannot evaluate tracked-operator flips directly. + #[pyo3(signature = (num_shots, seed=None))] + fn sample_tracked_op_batch( + &self, + num_shots: usize, + seed: Option, + ) -> PyResult>> { + use pecos_random::PecosRng; + use rand::RngExt; + + let mut rng = match seed { + Some(s) => PecosRng::seed_from_u64(s), + None => PecosRng::seed_from_u64(rand::rng().random()), + }; + + self.inner + .sample_tracked_operator_batch(num_shots, &mut rng) + .map_err(|e| PyErr::new::(e.to_string())) + } + /// Generate samples and store them in Rust memory as a `SampleBatch`. /// /// The batch can then be decoded by multiple decoders without re-sampling. @@ -3427,7 +3471,9 @@ impl PyDemSampler { let actual_seed = seed.unwrap_or_else(|| rand::rng().random()); let stats = self.inner.sample_statistics(num_shots, actual_seed); let observable_indices = self.inner.observable_ids(); - let tracked_op_indices = self.inner.tracked_operator_ids(); + let tracked_op_result = self.inner.tracked_operator_ids(); + let tracked_op_statistics_error = tracked_op_result.as_ref().err().map(ToString::to_string); + let tracked_op_indices = tracked_op_result.unwrap_or_default(); let per_observable = stats.observable_counts(&observable_indices); let per_tracked_op: Vec = tracked_op_indices .iter() @@ -3458,6 +3504,13 @@ impl PyDemSampler { dict.set_item("logical_rates", logical_rates)?; dict.set_item("tracked_op_rates", tracked_op_rates)?; dict.set_item("dem_output_rates", stats.dem_output_rates())?; + dict.set_item( + "tracked_op_statistics_supported", + tracked_op_statistics_error.is_none(), + )?; + if let Some(error) = tracked_op_statistics_error { + dict.set_item("tracked_op_statistics_error", error)?; + } Ok(dict.unbind()) } diff --git a/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py b/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py index a539f667e..c0ba3beb5 100644 --- a/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py +++ b/python/quantum-pecos/tests/pecos/test_pauli_string_bindings.py @@ -3,7 +3,7 @@ # Licensed under the Apache License, Version 2.0 import pytest -from pecos_rslib import Pauli, PauliString, X, Y, Z +from pecos_rslib import H, Pauli, PauliString, X, Y, Z def test_pauli_string_from_str_accepts_dense_and_sparse_formats() -> None: @@ -44,6 +44,18 @@ def test_pauli_string_tensor_result_is_pauli_string() -> None: assert tensor.get_paulis() == [(Pauli.X, 0), (Pauli.Y, 3)] +def test_pauli_string_tensor_equality_hash_and_text_forms_match() -> None: + tensor = X(0) & Y(3) + same_sparse = PauliString.from_sparse_str("X0 Y3") + same_dense = PauliString.from_dense_str("XIIY") + same_from_tuples = PauliString([(Pauli.Y, 3), (Pauli.X, 0)]) + + assert tensor == same_sparse == same_dense == same_from_tuples + assert len({tensor, same_sparse, same_dense, same_from_tuples}) == 1 + assert tensor.to_sparse_str() == "+X0 Y3" + assert tensor.to_dense_str() == "+XIIY" + + def test_pauli_string_explicit_from_dense_and_sparse_formats() -> None: expected = X(0) & Z(3) @@ -87,6 +99,9 @@ def test_pauli_string_tuple_constructor_rejects_duplicate_qubits() -> None: def test_pauli_string_tensor_rejects_overlapping_qubits() -> None: + with pytest.raises(ValueError, match=r"overlapping qubits: \[0\]"): + _ = X(0) & Y(0) + with pytest.raises(ValueError, match="tensor product requires disjoint Pauli support"): _ = X(0) & Z(0) @@ -94,6 +109,14 @@ def test_pauli_string_tensor_rejects_overlapping_qubits() -> None: _ = (X(0) & Y(2)) & Z(2) +def test_pauli_string_tensor_rejects_non_pauli_operands_explicitly() -> None: + with pytest.raises(TypeError): + _ = X(0) & H(1) + + with pytest.raises(TypeError): + _ = H(0) & H(1) + + def test_pauli_string_composition_allows_same_qubit() -> None: composed = X(0) * Z(0) diff --git a/python/quantum-pecos/tests/qec/test_dem_sampler.py b/python/quantum-pecos/tests/qec/test_dem_sampler.py index 0f4469fb8..0d8b43217 100644 --- a/python/quantum-pecos/tests/qec/test_dem_sampler.py +++ b/python/quantum-pecos/tests/qec/test_dem_sampler.py @@ -137,6 +137,10 @@ def test_dem_sampler_statistics() -> None: assert "dem_output_rates" in stats assert stats["per_dem_output"] == stats["per_observable"] assert stats["dem_output_rates"] == stats["logical_rates"] + assert stats["tracked_op_statistics_supported"] is True + assert "tracked_op_statistics_error" not in stats + assert sampler.sample_tracked_ops(seed=42) == [] + assert sampler.sample_tracked_op_batch(2, seed=42) == [[], []] assert stats["total_shots"] == 10000 assert 0.0 <= stats["logical_error_rate"] <= 1.0 @@ -170,6 +174,13 @@ def test_dem_sampler_tracked_op_labels() -> None: assert stats["per_observable"] == [] assert stats["per_tracked_op"] == [] assert stats["per_dem_output"] == [] + assert stats["tracked_op_statistics_supported"] is False + assert "cannot directly sample tracked operator flips" in stats["tracked_op_statistics_error"] + + with pytest.raises(RuntimeError, match="cannot directly sample tracked operator flips"): + sampler.sample_tracked_ops(seed=7) + with pytest.raises(RuntimeError, match="cannot directly sample tracked operator flips"): + sampler.sample_tracked_op_batch(4, seed=7) def test_dem_events_split_observables_and_tracked_ops() -> None: diff --git a/python/quantum-pecos/tests/qec/test_parsed_dem_sampler.py b/python/quantum-pecos/tests/qec/test_parsed_dem_sampler.py index b21f4db0c..f8a0966a8 100644 --- a/python/quantum-pecos/tests/qec/test_parsed_dem_sampler.py +++ b/python/quantum-pecos/tests/qec/test_parsed_dem_sampler.py @@ -146,6 +146,26 @@ def test_optimized_sampler_creation(self) -> None: assert sampler.num_mechanisms == 1 assert sampler.num_detectors == 2 + def test_optimized_sampler_projects_tracked_ops_but_fails_direct_sampling(self) -> None: + """Parsed PECOS DEM samplers preserve tracked-op IDs but do not sample them directly.""" + from pecos_rslib.qec import ParsedDem + + parsed = ParsedDem.from_string("error(0.1) D0 TP1") + sampler = parsed.to_dem_sampler() + + assert parsed.num_tracked_ops == 2 + assert sampler.num_detectors == 1 + assert sampler.num_dem_outputs == 0 + assert sampler.num_tracked_ops == 2 + + detectors, dem_outputs = sampler.sample(seed=11) + assert len(detectors) == 1 + assert isinstance(detectors[0], bool) + assert dem_outputs == [] + + with 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.../pecos-simulators/src/circuit_executor.rs | 197 +++++++---- 4 files changed, 355 insertions(+), 218 deletions(-) diff --git a/crates/benchmarks/benches/modules/tick_circuit_layout.rs b/crates/benchmarks/benches/modules/tick_circuit_layout.rs index 2c8da7325..99d0b8bba 100644 --- a/crates/benchmarks/benches/modules/tick_circuit_layout.rs +++ b/crates/benchmarks/benches/modules/tick_circuit_layout.rs @@ -22,7 +22,7 @@ use criterion::{BenchmarkId, Criterion, Throughput, measurement::Measurement}; use pecos_core::gate_type::GateType; use pecos_quantum::{Gate, QubitId, TickCircuit, TickCircuitSoA}; -use pecos_simulators::{CircuitExecutor, CliffordGateable, SparseStab}; +use pecos_simulators::{CliffordGateable, SparseStab, execute_batched}; use std::hint::black_box; const DISTANCES: &[usize] = &[3, 5, 7, 9, 11]; @@ -354,5 +354,5 @@ fn execute_gate_direct(sim: &mut S, gate: &Gate) -> usize { fn run_tick_circuit_soa(circuit: &TickCircuitSoA, num_qubits: usize) -> usize { let mut sim = SparseStab::new(num_qubits); - CircuitExecutor::new(circuit).run(&mut sim).len() + execute_batched(&circuit.batched, &mut sim).len() } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/tick_soa.rs b/crates/pecos-qec/src/fault_tolerance/propagator/tick_soa.rs index 3ab747afc..43047bead 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/tick_soa.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/tick_soa.rs @@ -1,20 +1,20 @@ -//! Optimized DOD-based tick fault analyzer using `TickCircuitSoA`. +//! Optimized tick fault analyzer using batched `TickCircuit` access. //! -//! This module provides [`TickFaultAnalyzerSoA`] which leverages the Structure of Arrays -//! layout of [`TickCircuitSoA`] for more cache-efficient fault analysis. +//! This module provides [`TickFaultAnalyzerSoA`] which uses the batched +//! full-fidelity command view of [`TickCircuit`] for cache-efficient fault +//! analysis without requiring a converted circuit representation. //! //! # Optimizations //! -//! 1. **Raw index access**: Uses u32 indices instead of `GateId` validation +//! 1. **Raw index access**: Uses local flattened gate indices //! 2. **Bitset for visited tracking**: O(1) membership check instead of `Vec::contains` //! 3. **Pre-computed tick indexes**: O(1) lookup for gates in each tick -//! 4. **Sorted qubit gates**: Gates per qubit sorted by tick for efficient backward traversal -//! 5. **Direct array access**: Skips Option-returning methods in hot loops +//! 4. **Direct array access**: Skips Option-returning methods in hot loops use super::SpacetimeLocation; use super::types::{DetectorId, FaultInfluence, FaultInfluenceMap, MeasurementId, TrackedOpId}; use pecos_core::{QubitId, gate_type::GateType}; -use pecos_quantum::tick_circuit_soa::TickCircuitSoA; +use pecos_quantum::TickCircuit; use pecos_simulators::{CliffordGateable, PauliProp}; // ============================================================================ @@ -29,7 +29,7 @@ pub struct AnalyzerWorkBuffers { /// Bitset for tracking processed gates in current tick processed_gates: Vec, /// Temporary storage for gates to process - gates_to_process: Vec, + gates_to_process: Vec, } impl AnalyzerWorkBuffers { @@ -65,11 +65,24 @@ impl AnalyzerWorkBuffers { // Optimized SOA-Based Fault Analyzer // ============================================================================ -/// Optimized fault analyzer for `TickCircuitSoA`. +#[derive(Debug, Clone)] +struct AnalyzerGate { + tick: usize, + gate_type: GateType, + qubits: Vec, +} + +/// Optimized fault analyzer for `TickCircuit`. /// /// Uses raw indices and bitsets for minimal overhead in hot paths. pub struct TickFaultAnalyzerSoA<'a> { - circuit: &'a TickCircuitSoA, + circuit: &'a TickCircuit, + /// Flattened full-fidelity gate command view. + gates: Vec, + /// Pre-computed index: tick -> gate indices + tick_gates: Vec>, + /// Maximum qubit index seen. + max_qubit: usize, /// Fault locations extracted from the circuit. locations: Vec, /// Pre-computed index: tick -> (`location_index`, before) pairs @@ -77,10 +90,11 @@ pub struct TickFaultAnalyzerSoA<'a> { } impl<'a> TickFaultAnalyzerSoA<'a> { - /// Creates a new analyzer for the given `SoA` circuit. + /// Creates a new analyzer for the given circuit. #[must_use] - pub fn new(circuit: &'a TickCircuitSoA) -> Self { - let locations = Self::extract_spacetime_locations(circuit); + pub fn new(circuit: &'a TickCircuit) -> Self { + let (gates, tick_gates, max_qubit) = Self::flatten_circuit(circuit); + let locations = Self::extract_spacetime_locations(&gates); // Build tick index for O(1) lookup let num_ticks = circuit.num_ticks(); @@ -93,41 +107,60 @@ impl<'a> TickFaultAnalyzerSoA<'a> { Self { circuit, + gates, + tick_gates, + max_qubit, locations, tick_locations, } } - /// Extracts spacetime locations using raw index access. - fn extract_spacetime_locations(circuit: &TickCircuitSoA) -> Vec { - let mut locations = Vec::new(); - let storage = &circuit.storage; + fn flatten_circuit(circuit: &TickCircuit) -> (Vec, Vec>, usize) { + let mut gates = Vec::new(); + let mut tick_gates = vec![Vec::new(); circuit.num_ticks()]; + let mut max_qubit = 0usize; - for idx in 0..storage.slot_count() { - if !storage.is_occupied(idx) { - continue; + for (tick, gate) in circuit.iter_gate_batches_with_tick() { + let idx = gates.len(); + let qubits = gate.qubits.to_vec(); + for qubit in &qubits { + max_qubit = max_qubit.max(qubit.index()); + } + if tick >= tick_gates.len() { + tick_gates.resize_with(tick + 1, Vec::new); } + tick_gates[tick].push(idx); + gates.push(AnalyzerGate { + tick, + gate_type: gate.gate_type, + qubits, + }); + } - let gate_type = storage.type_unchecked(idx); - let qubits = storage.qubits_unchecked(idx).to_vec(); - let tick = storage.tick_id_unchecked(idx) as usize; + (gates, tick_gates, max_qubit) + } + + /// Extracts spacetime locations using raw index access. + fn extract_spacetime_locations(gates: &[AnalyzerGate]) -> Vec { + let mut locations = Vec::new(); + for (idx, gate) in gates.iter().enumerate() { // Before location (fault before gate) locations.push(SpacetimeLocation { - tick, - qubits: qubits.clone(), + tick: gate.tick, + qubits: gate.qubits.clone(), before: true, - gate_type, + gate_type: gate.gate_type, gate_index: idx, }); // After location for most gates (except prep which resets) - if !matches!(gate_type, GateType::PZ | GateType::QAlloc) { + if !matches!(gate.gate_type, GateType::PZ | GateType::QAlloc) { locations.push(SpacetimeLocation { - tick, - qubits, + tick: gate.tick, + qubits: gate.qubits.clone(), before: false, - gate_type, + gate_type: gate.gate_type, gate_index: idx, }); } @@ -180,8 +213,8 @@ impl<'a> TickFaultAnalyzerSoA<'a> { } // Create work buffers - let max_qubit = self.circuit.max_qubit(); - let max_gate = self.circuit.storage.slot_count(); + let max_qubit = self.max_qubit; + let max_gate = self.gates.len(); let mut buffers = AnalyzerWorkBuffers::new(max_qubit, max_gate); // Backward propagate from each measurement @@ -213,25 +246,16 @@ impl<'a> TickFaultAnalyzerSoA<'a> { /// Extracts all measurements using raw index access. fn extract_measurements(&self) -> Vec { let mut measurements = Vec::new(); - let storage = &self.circuit.storage; - - for idx in 0..storage.slot_count() { - if !storage.is_occupied(idx) { - continue; - } - let gate_type = storage.type_unchecked(idx); - let basis = match gate_type { + for gate in &self.gates { + let basis = match gate.gate_type { GateType::MZ | GateType::MeasureFree => 0, // Z-basis _ => continue, }; - let tick = storage.tick_id_unchecked(idx) as usize; - let qubits = storage.qubits_unchecked(idx); - - for qubit in qubits { + for qubit in &gate.qubits { measurements.push(MeasurementId { - tick, + tick: gate.tick, qubit: qubit.index(), basis, }); @@ -297,25 +321,21 @@ impl<'a> TickFaultAnalyzerSoA<'a> { prop: &mut PauliProp, buffers: &mut AnalyzerWorkBuffers, ) { - let storage = &self.circuit.storage; - // Clear processed gates bitset for this tick buffers.gates_to_process.clear(); // Get gates in this tick directly from pre-computed index - let tick_gates = self.circuit.gates_in_tick_raw(tick_idx); + let tick_gates = self + .tick_gates + .get(tick_idx) + .map_or([].as_slice(), Vec::as_slice); // Find gates that touch active qubits for &gate_idx in tick_gates { - let idx = gate_idx as usize; - if !storage.is_occupied(idx) { - continue; - } - - let qubits = storage.qubits_unchecked(idx); + let gate = &self.gates[gate_idx]; // Check if any qubit is active - let touches_active = qubits.iter().any(|q| { + let touches_active = gate.qubits.iter().any(|q| { let qi = q.index(); qi < buffers.active_qubits.len() && buffers.active_qubits[qi] }); @@ -329,7 +349,7 @@ impl<'a> TickFaultAnalyzerSoA<'a> { // Note: We iterate by index to avoid borrow conflict let num_gates = buffers.gates_to_process.len(); for i in 0..num_gates { - let gate_idx = buffers.gates_to_process[i] as usize; + let gate_idx = buffers.gates_to_process[i]; self.apply_gate_backward_raw(gate_idx, prop, buffers); } } @@ -342,46 +362,50 @@ impl<'a> TickFaultAnalyzerSoA<'a> { prop: &mut PauliProp, buffers: &mut AnalyzerWorkBuffers, ) { - let storage = &self.circuit.storage; - let gate_type = storage.type_unchecked(idx); - let qubits = storage.qubits_unchecked(idx); + let gate = &self.gates[idx]; + let gate_type = gate.gate_type; + let qubits = gate.qubits.as_slice(); match gate_type { GateType::CX if qubits.len() >= 2 => { - let control = qubits[0].index(); - let target = qubits[1].index(); + for pair in qubits.chunks_exact(2) { + let control = pair[0].index(); + let target = pair[1].index(); - let ctrl_x = prop.contains_x(control); - let tgt_z = prop.contains_z(target); + let ctrl_x = prop.contains_x(control); + let tgt_z = prop.contains_z(target); - if ctrl_x { - prop.track_x(&[target]); - } - if tgt_z { - prop.track_z(&[control]); - } + if ctrl_x { + prop.track_x(&[target]); + } + if tgt_z { + prop.track_z(&[control]); + } - // Update active qubits - Self::update_active_qubit(control, prop, buffers); - Self::update_active_qubit(target, prop, buffers); + // Update active qubits + Self::update_active_qubit(control, prop, buffers); + Self::update_active_qubit(target, prop, buffers); + } } GateType::CZ if qubits.len() >= 2 => { - let q0 = qubits[0].index(); - let q1 = qubits[1].index(); + for pair in qubits.chunks_exact(2) { + let q0 = pair[0].index(); + let q1 = pair[1].index(); - let x0 = prop.contains_x(q0); - let x1 = prop.contains_x(q1); + let x0 = prop.contains_x(q0); + let x1 = prop.contains_x(q1); - if x0 { - prop.track_z(&[q1]); - } - if x1 { - prop.track_z(&[q0]); - } + if x0 { + prop.track_z(&[q1]); + } + if x1 { + prop.track_z(&[q0]); + } - Self::update_active_qubit(q0, prop, buffers); - Self::update_active_qubit(q1, prop, buffers); + Self::update_active_qubit(q0, prop, buffers); + Self::update_active_qubit(q1, prop, buffers); + } } GateType::CY @@ -394,42 +418,44 @@ impl<'a> TickFaultAnalyzerSoA<'a> { | GateType::SZZdg if qubits.len() >= 2 => { - let q0 = qubits[0]; - let q1 = qubits[1]; - let pair = [(q0, q1)]; - match gate_type { - GateType::CY => { - prop.cy(&pair); - } - GateType::SWAP => { - prop.swap(&pair); - } - GateType::SXX => { - prop.sxxdg(&pair); - } - GateType::SXXdg => { - prop.sxx(&pair); - } - GateType::SYY => { - prop.syydg(&pair); - } - GateType::SYYdg => { - prop.syy(&pair); - } - GateType::SZZ => { - prop.szzdg(&pair); - } - GateType::SZZdg => { - prop.szz(&pair); + for pair in qubits.chunks_exact(2) { + let q0 = pair[0]; + let q1 = pair[1]; + let pair = [(q0, q1)]; + match gate_type { + GateType::CY => { + prop.cy(&pair); + } + GateType::SWAP => { + prop.swap(&pair); + } + GateType::SXX => { + prop.sxxdg(&pair); + } + GateType::SXXdg => { + prop.sxx(&pair); + } + GateType::SYY => { + prop.syydg(&pair); + } + GateType::SYYdg => { + prop.syy(&pair); + } + GateType::SZZ => { + prop.szzdg(&pair); + } + GateType::SZZdg => { + prop.szz(&pair); + } + _ => unreachable!(), } - _ => unreachable!(), + Self::update_active_qubit(q0.index(), prop, buffers); + Self::update_active_qubit(q1.index(), prop, buffers); } - Self::update_active_qubit(q0.index(), prop, buffers); - Self::update_active_qubit(q1.index(), prop, buffers); } GateType::H => { - if let Some(qid) = qubits.first() { + for qid in qubits { let q = qid.index(); let has_x = prop.contains_x(q); let has_z = prop.contains_z(q); @@ -452,7 +478,7 @@ impl<'a> TickFaultAnalyzerSoA<'a> { | GateType::SYdg | GateType::F | GateType::Fdg => { - if let Some(qid) = qubits.first() { + for qid in qubits { let q = [QubitId(qid.index())]; match gate_type { GateType::SX => { @@ -480,7 +506,7 @@ impl<'a> TickFaultAnalyzerSoA<'a> { } GateType::SZ | GateType::SZdg => { - if let Some(qid) = qubits.first() { + for qid in qubits { let q = qid.index(); let has_x = prop.contains_x(q); @@ -689,22 +715,15 @@ impl<'a> TickFaultAnalyzerSoA<'a> { #[cfg(test)] mod tests { use super::*; - use pecos_quantum::tick_circuit_soa::TickCircuitSoABuilder; + use pecos_quantum::TickCircuit; #[test] fn test_basic_analysis() { - let mut builder = TickCircuitSoABuilder::new(); - builder - .tick() - .pz(&[0, 1]) - .tick() - .h(&[0]) - .tick() - .cx(&[(0, 1)]) - .tick() - .mz(&[0, 1]); - - let circuit = builder.build(); + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[0, 1]); + circuit.tick().h(&[0]); + circuit.tick().cx(&[(0, 1)]); + circuit.tick().mz(&[0, 1]); let analyzer = TickFaultAnalyzerSoA::new(&circuit); assert!(!analyzer.locations().is_empty()); @@ -717,20 +736,11 @@ mod tests { #[test] fn test_sparse_traversal() { - let mut builder = TickCircuitSoABuilder::new(); - builder - .tick() - .pz(&[0, 1, 2, 3]) - .tick() - .h(&[0]) - .h(&[2]) - .tick() - .cx(&[(0, 1)]) - .cx(&[(2, 3)]) - .tick() - .mz(&[0, 1, 2, 3]); - - let circuit = builder.build(); + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[0, 1, 2, 3]); + circuit.tick().h(&[0]).h(&[2]); + circuit.tick().cx(&[(0, 1)]).cx(&[(2, 3)]); + circuit.tick().mz(&[0, 1, 2, 3]); let analyzer = TickFaultAnalyzerSoA::new(&circuit); let map = analyzer.build_influence_map(); @@ -741,18 +751,11 @@ mod tests { #[test] fn test_tracked_op_propagation() { - let mut builder = TickCircuitSoABuilder::new(); - builder - .tick() - .pz(&[0, 1]) - .tick() - .h(&[0]) - .tick() - .cx(&[(0, 1)]) - .tick() - .mz(&[0, 1]); - - let circuit = builder.build(); + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[0, 1]); + circuit.tick().h(&[0]); + circuit.tick().cx(&[(0, 1)]); + circuit.tick().mz(&[0, 1]); let analyzer = TickFaultAnalyzerSoA::new(&circuit); let tracked_ops = [(&[] as &[usize], &[1usize] as &[usize])]; diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index c07dd6515..6f774a052 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -399,6 +399,21 @@ impl Tick { &self.gates } + /// Get the full-fidelity gate batches in this tick. + /// + /// In `TickCircuit`, a stored [`Gate`] command may represent one or more + /// gate applications on disjoint qubits. For example, + /// `cx(&[(0, 1), (2, 3)])` is one batch and two gate applications. + /// + /// This is intentionally the same data as [`gates`](Self::gates) today: the + /// batches preserve the complete [`Gate`] payload, including measurement + /// IDs and typed channel payloads. Future internal storage can make this + /// view cheaper or more data-oriented without changing consumers. + #[must_use] + pub fn gate_batches(&self) -> &[Gate] { + &self.gates + } + /// Get mutable access to the gates in this tick. pub fn gates_mut(&mut self) -> &mut [Gate] { &mut self.gates @@ -1662,6 +1677,15 @@ impl TickCircuit { self.ticks.iter().flat_map(Tick::gates) } + /// Iterate over full-fidelity gate batches in the circuit. + /// + /// This is the preferred API for consumers that execute or analyze batched + /// commands. Each yielded [`Gate`] may represent multiple gate applications + /// on disjoint qubits, and carries the full gate payload. + pub fn iter_gate_batches(&self) -> impl Iterator { + self.ticks.iter().flat_map(Tick::gate_batches) + } + /// Returns true if any tick contains an explicit channel operation. #[must_use] pub fn has_channel_operations(&self) -> bool { @@ -1692,6 +1716,13 @@ impl TickCircuit { .flat_map(|(tick_idx, tick)| tick.gates().iter().map(move |gate| (tick_idx, gate))) } + /// Iterate over full-fidelity gate batches with their tick index. + pub fn iter_gate_batches_with_tick(&self) -> impl Iterator { + self.ticks.iter().enumerate().flat_map(|(tick_idx, tick)| { + tick.gate_batches().iter().map(move |gate| (tick_idx, gate)) + }) + } + /// Iterate over ticks with their index. /// /// # Examples @@ -1712,6 +1743,16 @@ impl TickCircuit { self.ticks.iter().enumerate() } + /// Iterate over ticks through the batched command view. + /// + /// This is currently equivalent to [`iter_ticks`](Self::iter_ticks), because + /// each [`Tick`] stores full-fidelity batched gate commands. It exists so + /// batched consumers can depend on `TickCircuit` directly instead of a + /// converted execution-only circuit representation. + pub fn iter_ticks_batched(&self) -> impl Iterator { + self.iter_ticks() + } + /// Iterate over gates filtered by gate type. /// /// # Examples @@ -4821,16 +4862,32 @@ mod tests { let gates: Vec<_> = tc.iter_gates().collect(); assert_eq!(gates.len(), 3); + // Test explicit batched views. These currently mirror the stored gate + // commands and preserve full Gate payloads. + let batches: Vec<_> = tc.iter_gate_batches().collect(); + assert_eq!(batches.len(), 3); + assert_eq!(batches[0].gate_type, GateType::H); + assert_eq!(batches[0].num_gates(), 4); + assert_eq!(tc.get_tick(0).unwrap().gate_batches()[0].num_gates(), 4); + // Test iter_gates_with_tick let gates_with_tick: Vec<_> = tc.iter_gates_with_tick().collect(); assert_eq!(gates_with_tick.len(), 3); assert_eq!(gates_with_tick[0].0, 0); // First gate is in tick 0 assert_eq!(gates_with_tick[1].0, 1); // Second gate is in tick 1 + let batches_with_tick: Vec<_> = tc.iter_gate_batches_with_tick().collect(); + assert_eq!(batches_with_tick.len(), 3); + assert_eq!(batches_with_tick[2].0, 2); // Third batch is in tick 2 + // Test iter_ticks let ticks: Vec<_> = tc.iter_ticks().collect(); assert_eq!(ticks.len(), 3); + let batched_ticks: Vec<_> = tc.iter_ticks_batched().collect(); + assert_eq!(batched_ticks.len(), 3); + assert_eq!(batched_ticks[1].1.gate_batches()[0].gate_type, GateType::CX); + // Test iter_gates_by_type let h_gates: Vec<_> = tc.iter_gates_by_type(GateType::H).collect(); assert_eq!(h_gates.len(), 1); diff --git a/crates/pecos-simulators/src/circuit_executor.rs b/crates/pecos-simulators/src/circuit_executor.rs index 219f9178a..460fb6941 100644 --- a/crates/pecos-simulators/src/circuit_executor.rs +++ b/crates/pecos-simulators/src/circuit_executor.rs @@ -12,9 +12,10 @@ //! Batched circuit execution for Clifford simulators. //! -//! This module provides efficient circuit execution using the batched gate groups -//! from `TickCircuitSoA`. Instead of dispatching each gate individually, gates of -//! the same type are applied as a single batch call. +//! This module provides efficient circuit execution using the full-fidelity +//! batched gate commands stored by `TickCircuit`. Instead of dispatching each +//! individual gate application, stored batched commands are applied as one +//! simulator call. //! //! # Performance Benefits //! @@ -26,15 +27,13 @@ //! //! ``` //! use pecos_simulators::{SparseStab, CircuitExecutor}; -//! use pecos_quantum::TickCircuitSoA; +//! use pecos_quantum::TickCircuit; //! -//! let mut builder = TickCircuitSoA::builder(); -//! builder -//! .tick().pz(&[0, 1, 2, 3]) -//! .tick().h(&[0, 1, 2, 3]) -//! .tick().cx(&[(0, 1), (2, 3)]) -//! .tick().mz(&[0, 1, 2, 3]); -//! let circuit = builder.build(); +//! let mut circuit = TickCircuit::new(); +//! circuit.tick().pz(&[0, 1, 2, 3]); +//! circuit.tick().h(&[0, 1, 2, 3]); +//! circuit.tick().cx(&[(0, 1), (2, 3)]); +//! circuit.tick().mz(&[0, 1, 2, 3]); //! //! let mut sim = SparseStab::new(4); //! let executor = CircuitExecutor::new(&circuit); @@ -42,9 +41,9 @@ //! ``` use crate::{CliffordGateable, MeasurementResult}; -use pecos_core::QubitId; use pecos_core::gate_type::GateType; -use pecos_quantum::{GateBatch, TickBatches, TickCircuitSoA, TickGateGroups}; +use pecos_core::{Gate, QubitId}; +use pecos_quantum::{GateBatch, TickCircuit, TickGateGroups}; use smallvec::SmallVec; /// Convert a flat qubit slice `[c0, t0, c1, t1, ...]` to a vec of pairs. @@ -55,20 +54,20 @@ fn flat_to_pairs(qubits: &[QubitId]) -> SmallVec<[(QubitId, QubitId); 4]> { .collect() } -/// Executes a `TickCircuitSoA` on a Clifford simulator using batched operations. +/// Executes a `TickCircuit` on a Clifford simulator using batched operations. /// -/// This executor leverages the pre-grouped gate batches in `TickCircuitSoA` for -/// efficient execution with minimal dispatch overhead. +/// This executor leverages the full-fidelity batched gate commands in +/// `TickCircuit` for efficient execution with minimal dispatch overhead. pub struct CircuitExecutor<'a> { /// The circuit to execute. - circuit: &'a TickCircuitSoA, + circuit: &'a TickCircuit, } impl<'a> CircuitExecutor<'a> { /// Creates a new executor for the given circuit. #[inline] #[must_use] - pub fn new(circuit: &'a TickCircuitSoA) -> Self { + pub fn new(circuit: &'a TickCircuit) -> Self { Self { circuit } } @@ -79,34 +78,24 @@ impl<'a> CircuitExecutor<'a> { let mut measurements = Vec::new(); for (_tick_idx, tick) in self.circuit.iter_ticks_batched() { - Self::execute_tick(sim, tick, &mut measurements); + for batch in tick.gate_batches() { + Self::execute_gate_batch(sim, batch, &mut measurements); + } } measurements } - /// Runs a single tick on the simulator. - #[inline] - fn execute_tick( - sim: &mut S, - tick: &TickBatches, - measurements: &mut Vec, - ) { - for batch in tick.iter() { - Self::execute_batch(sim, batch, measurements); - } - } - - /// Executes a single batch of gates. + /// Executes a single full-fidelity batched gate command. /// /// This is the core dispatch function - one match per batch, not per gate. #[inline] - fn execute_batch( + fn execute_gate_batch( sim: &mut S, - batch: &GateBatch, + batch: &Gate, measurements: &mut Vec, ) { - execute_single_batch(sim, batch, measurements); + execute_gate_command(sim, batch, measurements); } } @@ -230,6 +219,108 @@ fn execute_single_batch( } } +/// Executes one full-fidelity `TickCircuit` gate command on a simulator. +#[inline] +fn execute_gate_command( + sim: &mut S, + gate: &Gate, + measurements: &mut Vec, +) { + let qubits = gate.qubits.as_slice(); + + match gate.gate_type { + GateType::I => { + sim.identity(qubits); + } + GateType::X => { + sim.x(qubits); + } + GateType::Y => { + sim.y(qubits); + } + GateType::Z => { + sim.z(qubits); + } + GateType::H => { + sim.h(qubits); + } + GateType::F => { + sim.f(qubits); + } + GateType::Fdg => { + sim.fdg(qubits); + } + GateType::SX => { + sim.sx(qubits); + } + GateType::SXdg => { + sim.sxdg(qubits); + } + GateType::SY => { + sim.sy(qubits); + } + GateType::SYdg => { + sim.sydg(qubits); + } + GateType::SZ => { + sim.sz(qubits); + } + GateType::SZdg => { + sim.szdg(qubits); + } + GateType::CX => { + let pairs = flat_to_pairs(qubits); + sim.cx(&pairs); + } + GateType::CY => { + let pairs = flat_to_pairs(qubits); + sim.cy(&pairs); + } + GateType::CZ => { + let pairs = flat_to_pairs(qubits); + sim.cz(&pairs); + } + GateType::SXX => { + let pairs = flat_to_pairs(qubits); + sim.sxx(&pairs); + } + GateType::SXXdg => { + let pairs = flat_to_pairs(qubits); + sim.sxxdg(&pairs); + } + GateType::SYY => { + let pairs = flat_to_pairs(qubits); + sim.syy(&pairs); + } + GateType::SYYdg => { + let pairs = flat_to_pairs(qubits); + sim.syydg(&pairs); + } + GateType::SZZ => { + let pairs = flat_to_pairs(qubits); + sim.szz(&pairs); + } + GateType::SZZdg => { + let pairs = flat_to_pairs(qubits); + sim.szzdg(&pairs); + } + GateType::SWAP => { + let pairs = flat_to_pairs(qubits); + sim.swap(&pairs); + } + GateType::PZ | GateType::QAlloc => { + sim.pz(qubits); + } + GateType::MZ | GateType::MeasureFree => { + measurements.extend(sim.mz(qubits)); + } + GateType::Idle => {} + other => { + panic!("Unsupported gate type in circuit executor: {other:?}"); + } + } +} + // ============================================================================ // DOD/ECS-Style Execution Pipeline // ============================================================================ @@ -287,22 +378,15 @@ impl GateSystemRegistry { mod tests { use super::*; use crate::SparseStab; - use pecos_quantum::TickCircuitSoA; + use pecos_quantum::{TickCircuit, TickCircuitSoA}; #[test] fn test_circuit_executor_basic() { - let mut builder = TickCircuitSoA::builder(); - builder - .tick() - .pz(&[0, 1]) - .tick() - .h(&[0]) - .tick() - .cx(&[(0, 1)]) - .tick() - .mz(&[0, 1]); - - let circuit = builder.build(); + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[0, 1]); + circuit.tick().h(&[0]); + circuit.tick().cx(&[(0, 1)]); + circuit.tick().mz(&[0, 1]); let mut sim = SparseStab::new(2); let executor = CircuitExecutor::new(&circuit); @@ -315,18 +399,11 @@ mod tests { #[test] fn test_circuit_executor_batched_gates() { // Create a circuit with multiple gates of same type per tick - let mut builder = TickCircuitSoA::builder(); - builder - .tick() - .pz(&[0, 1, 2, 3]) // 4 preps in one batch - .tick() - .h(&[0, 1, 2, 3]) // 4 H gates in one batch - .tick() - .cx(&[(0, 1), (2, 3)]) // 2 CX gates in one batch - .tick() - .mz(&[0, 1, 2, 3]); // 4 measurements in one batch - - let circuit = builder.build(); + let mut circuit = TickCircuit::new(); + circuit.tick().pz(&[0, 1, 2, 3]); // 4 preps in one batch + circuit.tick().h(&[0, 1, 2, 3]); // 4 H gates in one batch + circuit.tick().cx(&[(0, 1), (2, 3)]); // 2 CX gates in one batch + circuit.tick().mz(&[0, 1, 2, 3]); // 4 measurements in one batch let mut sim = SparseStab::new(4); let executor = CircuitExecutor::new(&circuit); From 8af551f474cec30b9bd9c26fde8763bacaa7bd80 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 11:40:02 -0600 Subject: [PATCH 102/125] Remove separate TickCircuitSoA representation --- .../benches/modules/tick_circuit_layout.rs | 84 +- crates/pecos-quantum/src/lib.rs | 5 - crates/pecos-quantum/src/tick_circuit_soa.rs | 1569 ----------------- .../pecos-simulators/src/circuit_executor.rs | 143 +- crates/pecos-simulators/src/lib.rs | 2 +- 5 files changed, 23 insertions(+), 1780 deletions(-) delete mode 100644 crates/pecos-quantum/src/tick_circuit_soa.rs diff --git a/crates/benchmarks/benches/modules/tick_circuit_layout.rs b/crates/benchmarks/benches/modules/tick_circuit_layout.rs index 99d0b8bba..c7e05f848 100644 --- a/crates/benchmarks/benches/modules/tick_circuit_layout.rs +++ b/crates/benchmarks/benches/modules/tick_circuit_layout.rs @@ -10,19 +10,17 @@ // or implied. See the License for the specific language governing permissions and limitations under // the License. -//! TickCircuit vs TickCircuitSoA layout benchmarks. +//! TickCircuit batched layout benchmarks. //! -//! These benchmarks measure the current representation tradeoff before making -//! any storage-refactor decision: +//! These benchmarks measure the current batched `TickCircuit` access patterns: //! - direct TickCircuit traversal, -//! - TickCircuitSoA batched traversal, -//! - TickCircuit -> TickCircuitSoA conversion cost, and -//! - direct vs batched simulator execution with and without conversion cost. +//! - explicit batched TickCircuit traversal, and +//! - direct vs `CircuitExecutor` simulator execution. use criterion::{BenchmarkId, Criterion, Throughput, measurement::Measurement}; use pecos_core::gate_type::GateType; -use pecos_quantum::{Gate, QubitId, TickCircuit, TickCircuitSoA}; -use pecos_simulators::{CliffordGateable, SparseStab, execute_batched}; +use pecos_quantum::{Gate, QubitId, TickCircuit}; +use pecos_simulators::{CircuitExecutor, CliffordGateable, SparseStab}; use std::hint::black_box; const DISTANCES: &[usize] = &[3, 5, 7, 9, 11]; @@ -33,9 +31,7 @@ struct LayoutSpec { label: String, num_qubits: usize, gate_count: usize, - gate_batch_count: usize, tick_circuit: TickCircuit, - soa_circuit: TickCircuitSoA, } pub fn benchmarks(c: &mut Criterion) { @@ -44,23 +40,18 @@ pub fn benchmarks(c: &mut Criterion) { .map(|&distance| { let rounds = distance; let tick_circuit = build_surface_like_tick_circuit(distance, rounds); - let soa_circuit = TickCircuitSoA::from(&tick_circuit); let num_qubits = surface_like_num_qubits(distance); let gate_count = tick_circuit.gate_count(); - let gate_batch_count = tick_circuit.gate_batch_count(); LayoutSpec { label: format!("d{distance}_r{rounds}"), num_qubits, gate_count, - gate_batch_count, tick_circuit, - soa_circuit, } }) .collect::>(); bench_traversal(c, &specs); - bench_conversion(c, &specs); bench_execution(c, &specs); bench_amortized_execution(c, &specs); } @@ -78,33 +69,10 @@ fn bench_traversal(c: &mut Criterion, specs: &[LayoutSpec]) { }, ); group.bench_with_input( - BenchmarkId::new("tick_circuit_soa_batched", &spec.label), + BenchmarkId::new("tick_circuit_gate_batches", &spec.label), spec, |b, spec| { - b.iter(|| black_box(traverse_tick_circuit_soa(black_box(&spec.soa_circuit)))); - }, - ); - } - - group.finish(); -} - -fn bench_conversion(c: &mut Criterion, specs: &[LayoutSpec]) { - let mut group = c.benchmark_group("tick_circuit_layout/conversion"); - - for spec in specs { - group.throughput(Throughput::Elements(spec.gate_count as u64)); - group.bench_with_input( - BenchmarkId::new( - format!("to_soa_{}_batches", spec.gate_batch_count), - &spec.label, - ), - spec, - |b, spec| { - b.iter(|| { - let soa = TickCircuitSoA::from(black_box(&spec.tick_circuit)); - black_box((soa.gate_count(), soa.gate_batch_count())) - }); + b.iter(|| black_box(traverse_tick_circuit_batched(black_box(&spec.tick_circuit)))); }, ); } @@ -130,22 +98,12 @@ fn bench_execution(c: &mut Criterion, specs: &[LayoutSpec]) { }, ); group.bench_with_input( - BenchmarkId::new("soa_with_conversion", &spec.label), - spec, - |b, spec| { - b.iter(|| { - let soa = TickCircuitSoA::from(black_box(&spec.tick_circuit)); - black_box(run_tick_circuit_soa(black_box(&soa), spec.num_qubits)) - }); - }, - ); - group.bench_with_input( - BenchmarkId::new("soa_preconverted", &spec.label), + BenchmarkId::new("circuit_executor", &spec.label), spec, |b, spec| { b.iter(|| { - black_box(run_tick_circuit_soa( - black_box(&spec.soa_circuit), + black_box(run_tick_circuit_executor( + black_box(&spec.tick_circuit), spec.num_qubits, )) }); @@ -179,14 +137,14 @@ fn bench_amortized_execution(c: &mut Criterion, specs: &[Layo }, ); group.bench_with_input( - BenchmarkId::new("soa_preconverted", &spec.label), + BenchmarkId::new("circuit_executor", &spec.label), spec, |b, spec| { b.iter(|| { let mut total = 0usize; for _ in 0..AMORTIZED_SHOTS { - total = total.wrapping_add(run_tick_circuit_soa( - black_box(&spec.soa_circuit), + total = total.wrapping_add(run_tick_circuit_executor( + black_box(&spec.tick_circuit), spec.num_qubits, )); } @@ -303,14 +261,12 @@ fn traverse_tick_circuit(circuit: &TickCircuit) -> usize { total } -fn traverse_tick_circuit_soa(circuit: &TickCircuitSoA) -> usize { +fn traverse_tick_circuit_batched(circuit: &TickCircuit) -> usize { let mut total = 0usize; - for (tick_idx, tick) in circuit.iter_ticks_batched() { + for (tick_idx, batch) in circuit.iter_gate_batches_with_tick() { total = total.wrapping_add(tick_idx); - for batch in tick.iter() { - total = total.wrapping_add(batch.gate_count()); - total = total.wrapping_add(batch.qubits().len()); - } + total = total.wrapping_add(batch.num_gates()); + total = total.wrapping_add(batch.qubits.len()); } total } @@ -352,7 +308,7 @@ fn execute_gate_direct(sim: &mut S, gate: &Gate) -> usize { } } -fn run_tick_circuit_soa(circuit: &TickCircuitSoA, num_qubits: usize) -> usize { +fn run_tick_circuit_executor(circuit: &TickCircuit, num_qubits: usize) -> usize { let mut sim = SparseStab::new(num_qubits); - execute_batched(&circuit.batched, &mut sim).len() + CircuitExecutor::new(circuit).run(&mut sim).len() } diff --git a/crates/pecos-quantum/src/lib.rs b/crates/pecos-quantum/src/lib.rs index 418becf8f..44bf47a1b 100644 --- a/crates/pecos-quantum/src/lib.rs +++ b/crates/pecos-quantum/src/lib.rs @@ -75,7 +75,6 @@ pub mod pauli_sequence; pub mod pauli_set; pub mod stabilizer_group; mod tick_circuit; -pub mod tick_circuit_soa; pub mod unitary_matrix; #[cfg(feature = "hugr")] @@ -90,10 +89,6 @@ pub use tick_circuit::{ CustomGateError, GateSignatureMismatchError, QubitConflictError, Tick, TickCircuit, TickGateError, TickHandle, TickMeasRef, TickMeasureHandle, TickPrepHandle, }; -pub use tick_circuit_soa::{ - CircuitIndexes, GateBatch, GateId, GateStorage, MetadataStorage, TickBatches, TickCircuitSoA, - TickCircuitSoABuilder, TickGateGroups, -}; // Re-export commonly used types from dependencies pub use pecos_core::gate_type::GateType; diff --git a/crates/pecos-quantum/src/tick_circuit_soa.rs b/crates/pecos-quantum/src/tick_circuit_soa.rs deleted file mode 100644 index da2b5df5f..000000000 --- a/crates/pecos-quantum/src/tick_circuit_soa.rs +++ /dev/null @@ -1,1569 +0,0 @@ -//! Data-Oriented Design (DOD) `TickCircuit` implementation. -//! -//! This module provides `TickCircuitSoA`, an alternative representation of tick-based -//! quantum circuits optimized for **batched simulation**. -//! -//! # Design Goals -//! -//! 1. **Batched gate execution**: Gates grouped by type within each tick for batch execution -//! 2. **Cache-friendly memory layout**: Qubits for same-type gates stored contiguously -//! 3. **O(1) lookups**: Pre-computed indexes for qubit-to-gate and tick-to-gate queries -//! 4. **Efficient simulation**: Direct batch calls to simulator without per-gate dispatch -//! -//! # Architecture -//! -//! ```text -//! ┌─────────────────────────────────────────────────────────────────┐ -//! │ TickCircuitSoA │ -//! ├─────────────────────────────────────────────────────────────────┤ -//! │ TickGateGroups (simulation-optimized) │ -//! │ ├── ticks[0]: [H→[q0,q1], CX→[c0,t0,c1,t1], ...] │ -//! │ ├── ticks[1]: [Mz→[q0,q1,q2], ...] │ -//! │ └── ... │ -//! ├─────────────────────────────────────────────────────────────────┤ -//! │ GateStorage (SoA layout for individual gate access) │ -//! │ ├── types: [H, CX, H, Mz, ...] (Vec) │ -//! │ ├── tick_ids: [0, 0, 1, 2, ...] (Vec) │ -//! │ ├── qubit_spans: [(0,1), (1,3), (3,4), ...] (Vec<(u32,u32)>) │ -//! │ └── qubits: [0, 0, 1, 0, ...] (Vec) │ -//! ├─────────────────────────────────────────────────────────────────┤ -//! │ CircuitIndexes │ -//! │ ├── tick_gates: [[0,1], [2,3], ...] (Vec>) │ -//! │ ├── qubit_to_gates: [[0,1], [1], ...] (Vec) │ -//! │ └── max_qubit: usize │ -//! └─────────────────────────────────────────────────────────────────┘ -//! ``` -//! -//! # Batched Simulation -//! -//! The key optimization is grouping gates by type within each tick: -//! -//! ```text -//! // Without batching (gate-by-gate): -//! for gate in tick.gates(): -//! match gate.type: -//! H => sim.h(&[gate.qubit]) // 4 separate calls -//! H => sim.h(&[gate.qubit]) -//! CX => sim.cx(&[c, t]) -//! CX => sim.cx(&[c, t]) -//! -//! // With batching (one call per type): -//! sim.h(&[q0, q1, q2, q3]) // 1 batched call -//! sim.cx(&[c0, t0, c1, t1]) // 1 batched call -//! ``` -//! -//! # Usage -//! -//! ``` -//! use pecos_quantum::TickCircuitSoA; -//! -//! // Build using the builder pattern -//! let mut builder = TickCircuitSoA::builder(); -//! builder -//! .tick() -//! .h(&[0, 1]) -//! .cx(&[(0, 1)]) -//! .tick() -//! .mz(&[0, 1]); -//! let circuit = builder.build(); -//! ``` -//! -//! With a simulator, the batched iteration looks like: -//! -//! ```text -//! for (tick_idx, tick) in circuit.iter_ticks_batched() { -//! for batch in tick.iter() { -//! match batch.gate_type { -//! GateType::H => sim.h(batch.qubits()), -//! GateType::CX => sim.cx(batch.qubits()), -//! GateType::MZ => { sim.mz(batch.qubits()); } -//! // ... -//! } -//! } -//! } -//! ``` - -use crate::Attribute; -use pecos_core::gate_type::GateType; -use pecos_core::{Angle64, Gate, QubitId}; -use smallvec::SmallVec; -use std::collections::BTreeMap; - -// ============================================================================ -// Gate Batching for Simulation -// ============================================================================ - -/// A batch of gates of the same type, ready for efficient batch application. -/// -/// For single-qubit gates, `qubits` contains one qubit per gate instance. -/// For two-qubit gates, `qubits` contains pairs: `[c0, t0, c1, t1, ...]`. -#[derive(Debug, Clone)] -pub struct GateBatch { - /// The gate type for all gates in this batch. - pub gate_type: GateType, - /// Qubits for batch application (contiguous for cache efficiency). - /// Single-qubit: `[q0, q1, q2, ...]` - /// Two-qubit: `[c0, t0, c1, t1, ...]` (control-target pairs) - pub qubits: SmallVec<[QubitId; 16]>, - /// Angles for parameterized gates (one per gate instance). - pub angles: SmallVec<[Angle64; 4]>, - /// Parameters for gates with params (e.g., idle duration). - pub params: SmallVec<[f64; 4]>, -} - -impl GateBatch { - /// Creates a new empty batch for the given gate type. - #[inline] - #[must_use] - pub fn new(gate_type: GateType) -> Self { - Self { - gate_type, - qubits: SmallVec::new(), - angles: SmallVec::new(), - params: SmallVec::new(), - } - } - - /// Returns the qubits for batch application. - #[inline] - #[must_use] - pub fn qubits(&self) -> &[QubitId] { - &self.qubits - } - - /// Returns the angles for parameterized gates. - #[inline] - #[must_use] - pub fn angles(&self) -> &[Angle64] { - &self.angles - } - - /// Returns the number of gates in this batch. - #[inline] - #[must_use] - pub fn gate_count(&self) -> usize { - self.gate_type.num_gates(self.qubits.len()) - } - - /// Returns true if the batch is empty. - #[inline] - #[must_use] - pub fn is_empty(&self) -> bool { - self.qubits.is_empty() - } - - /// Adds a gate's qubits to this batch. - #[inline] - pub fn add_qubits(&mut self, qubits: &[QubitId]) { - self.qubits.extend_from_slice(qubits); - } - - /// Adds a gate's angle to this batch. - #[inline] - pub fn add_angle(&mut self, angle: Angle64) { - self.angles.push(angle); - } -} - -/// Gates for a single tick, grouped by type for batch application. -#[derive(Debug, Clone, Default)] -pub struct TickBatches { - /// Gate batches, one per gate type that appears in this tick. - /// Ordered by insertion (first gate type seen comes first). - pub batches: SmallVec<[GateBatch; 8]>, -} - -impl TickBatches { - /// Creates a new empty tick. - #[must_use] - pub fn new() -> Self { - Self::default() - } - - /// Returns an iterator over the batches. - #[inline] - pub fn iter(&self) -> impl Iterator { - self.batches.iter() - } - - /// Returns the number of batches. - #[inline] - #[must_use] - pub fn batch_count(&self) -> usize { - self.batches.len() - } - - /// Returns the total number of gates in this tick. - #[must_use] - pub fn gate_count(&self) -> usize { - self.batches.iter().map(GateBatch::gate_count).sum() - } - - /// Adds a gate to the appropriate batch (creates batch if needed). - /// - /// # Panics - /// Panics if internal batch list is unexpectedly empty after insertion. - pub fn add_gate(&mut self, gate_type: GateType, qubits: &[QubitId], angles: &[Angle64]) { - // Find or create batch for this gate type - let batch = if let Some(batch) = self.batches.iter_mut().find(|b| b.gate_type == gate_type) - { - batch - } else { - self.batches.push(GateBatch::new(gate_type)); - self.batches.last_mut().expect("batch was just pushed") - }; - - batch.add_qubits(qubits); - for &angle in angles { - batch.add_angle(angle); - } - } - - /// Returns the batch for a specific gate type, if present. - #[inline] - #[must_use] - pub fn batch_for_type(&self, gate_type: GateType) -> Option<&GateBatch> { - self.batches.iter().find(|b| b.gate_type == gate_type) - } -} - -/// Pre-grouped gates by type for each tick, optimized for batched simulation. -/// -/// This is the primary structure for efficient circuit execution: -/// - Gates are grouped by type within each tick -/// - Qubits for same-type gates are stored contiguously -/// - Enables single batch calls to the simulator per gate type -#[derive(Debug, Clone, Default)] -pub struct TickGateGroups { - /// For each tick, the batched gates. - pub ticks: Vec, - /// Number of ticks. - pub num_ticks: usize, - /// Maximum qubit index seen. - pub max_qubit: usize, -} - -impl TickGateGroups { - /// Creates empty gate groups. - #[must_use] - pub fn new() -> Self { - Self::default() - } - - /// Returns the number of ticks. - #[inline] - #[must_use] - pub fn num_ticks(&self) -> usize { - self.num_ticks - } - - /// Returns the batches for a specific tick. - #[inline] - #[must_use] - pub fn tick(&self, tick_idx: usize) -> Option<&TickBatches> { - self.ticks.get(tick_idx) - } - - /// Returns an iterator over all ticks. - #[inline] - pub fn iter_ticks(&self) -> impl Iterator { - self.ticks.iter().enumerate() - } - - /// Ensures capacity for the given tick index. - fn ensure_tick(&mut self, tick_idx: usize) { - if tick_idx >= self.ticks.len() { - self.ticks.resize_with(tick_idx + 1, TickBatches::new); - } - self.num_ticks = self.num_ticks.max(tick_idx + 1); - } - - /// Adds a gate to the appropriate tick and batch. - pub fn add_gate( - &mut self, - tick_idx: usize, - gate_type: GateType, - qubits: &[QubitId], - angles: &[Angle64], - ) { - self.ensure_tick(tick_idx); - self.ticks[tick_idx].add_gate(gate_type, qubits, angles); - - // Track max qubit - for qubit in qubits { - self.max_qubit = self.max_qubit.max(qubit.index()); - } - } - - /// Clears all gate groups. - pub fn clear(&mut self) { - self.ticks.clear(); - self.num_ticks = 0; - self.max_qubit = 0; - } - - /// Returns the total number of gates across all ticks. - #[must_use] - pub fn total_gate_count(&self) -> usize { - self.ticks.iter().map(TickBatches::gate_count).sum() - } -} - -// ============================================================================ -// Gate ID (Stable, Generational) -// ============================================================================ - -/// A stable identifier for a gate in a `TickCircuitSoA`. -/// -/// Unlike raw indices, `GateId` includes a generation counter that allows -/// detecting use-after-free when gates are removed. This provides safety -/// without the overhead of reference counting. -#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] -pub struct GateId { - /// Index into the gate storage arrays. - index: u32, - /// Generation counter for detecting stale IDs. - generation: u16, -} - -impl GateId { - /// Creates a new `GateId`. - #[inline] - #[must_use] - pub const fn new(index: u32, generation: u16) -> Self { - Self { index, generation } - } - - /// Returns the raw index (use with caution). - #[inline] - #[must_use] - pub const fn index(self) -> usize { - self.index as usize - } - - /// Returns the generation. - #[inline] - #[must_use] - pub const fn generation(self) -> u16 { - self.generation - } -} - -// ============================================================================ -// Gate Storage (SoA Layout) -// ============================================================================ - -/// Structure-of-Arrays storage for gate data. -/// -/// All gates are stored in parallel arrays for cache-friendly access. -/// Variable-length data (qubits, angles) uses span-based indexing into -/// contiguous backing arrays. -#[derive(Debug, Clone, Default)] -pub struct GateStorage { - // Core gate data (one element per gate) - /// Gate types (H, CX, Mz, etc.) - pub types: Vec, - /// Which tick each gate belongs to - pub tick_ids: Vec, - /// Span (start, end) into the qubits array - pub qubit_spans: Vec<(u32, u32)>, - /// Span (start, end) into the angles array - pub angle_spans: Vec<(u32, u32)>, - /// Generation counter for each slot (for `GateId` validation) - pub generations: Vec, - /// Whether each slot is occupied (for sparse storage after removals) - pub occupied: Vec, - - // Backing arrays for variable-length data - /// All qubits, indexed by `qubit_spans` - pub qubits: Vec, - /// All angles, indexed by `angle_spans` - pub angles: Vec, - /// All params (e.g., idle duration), indexed similarly - pub param_spans: Vec<(u32, u32)>, - pub params: Vec, - - // Free list for slot reuse after removal - free_slots: Vec, -} - -impl GateStorage { - /// Creates empty gate storage. - #[must_use] - pub fn new() -> Self { - Self::default() - } - - /// Creates gate storage with pre-allocated capacity. - #[must_use] - pub fn with_capacity(gate_capacity: usize, qubit_capacity: usize) -> Self { - Self { - types: Vec::with_capacity(gate_capacity), - tick_ids: Vec::with_capacity(gate_capacity), - qubit_spans: Vec::with_capacity(gate_capacity), - angle_spans: Vec::with_capacity(gate_capacity), - generations: Vec::with_capacity(gate_capacity), - occupied: Vec::with_capacity(gate_capacity), - qubits: Vec::with_capacity(qubit_capacity), - angles: Vec::new(), - param_spans: Vec::with_capacity(gate_capacity), - params: Vec::new(), - free_slots: Vec::new(), - } - } - - /// Returns the number of gates (including removed slots). - #[inline] - #[must_use] - pub fn len(&self) -> usize { - self.types.len() - } - - /// Returns true if there are no gates. - #[inline] - #[must_use] - pub fn is_empty(&self) -> bool { - self.types.is_empty() - } - - /// Returns the number of active (non-removed) gates. - #[must_use] - pub fn active_count(&self) -> usize { - self.occupied.iter().filter(|&&o| o).count() - } - - /// Returns the number of active gates. - #[must_use] - pub fn active_gate_count(&self) -> usize { - (0..self.types.len()) - .filter(|&idx| self.occupied[idx]) - .map(|idx| { - let (qubit_start, qubit_end) = self.qubit_spans[idx]; - self.types[idx].num_gates((qubit_end as usize).saturating_sub(qubit_start as usize)) - }) - .sum() - } - - fn gate_from_index(&self, idx: usize) -> Gate { - let (qubit_start, qubit_end) = self.qubit_spans[idx]; - let (angle_start, angle_end) = self.angle_spans[idx]; - let (param_start, param_end) = self.param_spans[idx]; - Gate::new( - self.types[idx], - self.angles[angle_start as usize..angle_end as usize].to_vec(), - self.params[param_start as usize..param_end as usize].to_vec(), - self.qubits[qubit_start as usize..qubit_end as usize].to_vec(), - ) - } - - /// Adds a gate and returns its ID. - pub fn add_gate( - &mut self, - gate_type: GateType, - tick_id: u16, - qubits: &[QubitId], - angles: &[Angle64], - params: &[f64], - ) -> GateId { - let (index, generation) = if let Some(slot) = self.free_slots.pop() { - // Reuse a freed slot - let idx = slot as usize; - self.generations[idx] = self.generations[idx].wrapping_add(1); - self.types[idx] = gate_type; - self.tick_ids[idx] = tick_id; - self.occupied[idx] = true; - (slot, self.generations[idx]) - } else { - // Allocate new slot - #[allow(clippy::cast_possible_truncation)] // gate index fits in u32 - let idx = self.types.len() as u32; - self.types.push(gate_type); - self.tick_ids.push(tick_id); - self.generations.push(0); - self.occupied.push(true); - // Placeholders for spans - will be set below - self.qubit_spans.push((0, 0)); - self.angle_spans.push((0, 0)); - self.param_spans.push((0, 0)); - (idx, 0) - }; - - let idx = index as usize; - - // Add qubits - #[allow(clippy::cast_possible_truncation)] // qubit pool index fits in u32 - let qubit_start = self.qubits.len() as u32; - self.qubits.extend_from_slice(qubits); - #[allow(clippy::cast_possible_truncation)] // qubit pool index fits in u32 - let qubit_end = self.qubits.len() as u32; - self.qubit_spans[idx] = (qubit_start, qubit_end); - - // Add angles - #[allow(clippy::cast_possible_truncation)] // angle pool index fits in u32 - let angle_start = self.angles.len() as u32; - self.angles.extend_from_slice(angles); - #[allow(clippy::cast_possible_truncation)] // angle pool index fits in u32 - let angle_end = self.angles.len() as u32; - self.angle_spans[idx] = (angle_start, angle_end); - - // Add params - #[allow(clippy::cast_possible_truncation)] // param pool index fits in u32 - let param_start = self.params.len() as u32; - self.params.extend_from_slice(params); - #[allow(clippy::cast_possible_truncation)] // param pool index fits in u32 - let param_end = self.params.len() as u32; - self.param_spans[idx] = (param_start, param_end); - - GateId::new(index, generation) - } - - /// Validates that a `GateId` is still valid. - #[inline] - #[must_use] - pub fn is_valid(&self, id: GateId) -> bool { - let idx = id.index(); - idx < self.len() && self.generations[idx] == id.generation() && self.occupied[idx] - } - - /// Returns the gate type for a valid ID. - #[inline] - #[must_use] - pub fn gate_type(&self, id: GateId) -> Option { - if self.is_valid(id) { - Some(self.types[id.index()]) - } else { - None - } - } - - /// Returns the tick ID for a valid gate. - #[inline] - #[must_use] - pub fn tick_id(&self, id: GateId) -> Option { - if self.is_valid(id) { - Some(self.tick_ids[id.index()]) - } else { - None - } - } - - // ========================================================================= - // Unchecked accessors for hot paths (internal use) - // ========================================================================= - - /// Returns the gate type without validation. Use only when index is known valid. - #[inline] - #[must_use] - pub fn type_unchecked(&self, idx: usize) -> GateType { - self.types[idx] - } - - /// Returns the tick ID without validation. - #[inline] - #[must_use] - pub fn tick_id_unchecked(&self, idx: usize) -> u16 { - self.tick_ids[idx] - } - - /// Returns the qubits without validation. - #[inline] - #[must_use] - pub fn qubits_unchecked(&self, idx: usize) -> &[QubitId] { - let (start, end) = self.qubit_spans[idx]; - &self.qubits[start as usize..end as usize] - } - - /// Returns whether the slot is occupied. - #[inline] - #[must_use] - pub fn is_occupied(&self, idx: usize) -> bool { - idx < self.occupied.len() && self.occupied[idx] - } - - /// Returns the total number of slots (for iteration bounds). - #[inline] - #[must_use] - pub fn slot_count(&self) -> usize { - self.types.len() - } - - /// Returns the qubits for a valid gate. - #[inline] - #[must_use] - pub fn gate_qubits(&self, id: GateId) -> Option<&[QubitId]> { - if self.is_valid(id) { - let (start, end) = self.qubit_spans[id.index()]; - Some(&self.qubits[start as usize..end as usize]) - } else { - None - } - } - - /// Returns the angles for a valid gate. - #[inline] - #[must_use] - pub fn gate_angles(&self, id: GateId) -> Option<&[Angle64]> { - if self.is_valid(id) { - let (start, end) = self.angle_spans[id.index()]; - Some(&self.angles[start as usize..end as usize]) - } else { - None - } - } - - /// Returns the params for a valid gate. - #[inline] - #[must_use] - pub fn gate_params(&self, id: GateId) -> Option<&[f64]> { - if self.is_valid(id) { - let (start, end) = self.param_spans[id.index()]; - Some(&self.params[start as usize..end as usize]) - } else { - None - } - } - - /// Removes a gate by ID. The slot can be reused. - pub fn remove(&mut self, id: GateId) -> bool { - if self.is_valid(id) { - let idx = id.index(); - self.occupied[idx] = false; - self.free_slots.push(id.index); - true - } else { - false - } - } - - /// Clears all gates. - pub fn clear(&mut self) { - self.types.clear(); - self.tick_ids.clear(); - self.qubit_spans.clear(); - self.angle_spans.clear(); - self.param_spans.clear(); - self.generations.clear(); - self.occupied.clear(); - self.qubits.clear(); - self.angles.clear(); - self.params.clear(); - self.free_slots.clear(); - } - - /// Iterator over all valid gate IDs. - pub fn iter_ids(&self) -> impl Iterator + '_ { - (0..self.len()).filter_map(move |idx| { - if self.occupied[idx] { - #[allow(clippy::cast_possible_truncation)] // gate index fits in u32 - Some(GateId::new(idx as u32, self.generations[idx])) - } else { - None - } - }) - } -} - -// ============================================================================ -// Circuit Indexes -// ============================================================================ - -/// Pre-computed indexes for efficient circuit queries. -/// -/// Uses raw u32 indices instead of `GateIds` for minimal overhead in hot paths. -#[derive(Debug, Clone, Default)] -pub struct CircuitIndexes { - /// For each tick, the list of gate indices in that tick. - /// Using Vec> for simplicity; could use CSR format for less allocation. - pub tick_gates: Vec>, - - /// For each qubit, the list of gate indices that touch it. - /// Indexed by qubit index; grows dynamically. - /// Uses u32 instead of `GateId` to avoid validation overhead. - pub qubit_to_gates: Vec>, - - /// For each qubit, gates sorted by tick (for efficient backward traversal). - /// Each entry is (`tick_id`, `gate_idx`). - pub qubit_gates_by_tick: Vec>, - - /// Maximum qubit index seen. - pub max_qubit: usize, - - /// Number of ticks. - pub num_ticks: usize, -} - -impl CircuitIndexes { - /// Creates empty indexes. - #[must_use] - pub fn new() -> Self { - Self::default() - } - - /// Ensures the qubit index can accommodate the given qubit. - fn ensure_qubit_capacity(&mut self, qubit: usize) { - if qubit >= self.qubit_to_gates.len() { - self.qubit_to_gates.resize(qubit + 1, SmallVec::new()); - self.qubit_gates_by_tick.resize(qubit + 1, Vec::new()); - } - self.max_qubit = self.max_qubit.max(qubit); - } - - /// Registers a gate in the indexes (using raw index). - pub fn register_gate_raw(&mut self, gate_idx: u32, tick_id: u16, qubits: &[QubitId]) { - // Add to tick index - let tick = tick_id as usize; - if tick >= self.tick_gates.len() { - self.tick_gates.resize(tick + 1, Vec::new()); - } - self.tick_gates[tick].push(gate_idx); - self.num_ticks = self.num_ticks.max(tick + 1); - - // Add to qubit indexes - for qubit in qubits { - let q = qubit.index(); - self.ensure_qubit_capacity(q); - self.qubit_to_gates[q].push(gate_idx); - self.qubit_gates_by_tick[q].push((tick_id, gate_idx)); - } - } - - /// Registers a gate in the qubit index (`GateId` version for compatibility). - pub fn register_gate(&mut self, gate_id: GateId, qubits: &[QubitId]) { - for qubit in qubits { - let q = qubit.index(); - self.ensure_qubit_capacity(q); - self.qubit_to_gates[q].push(gate_id.index); - } - } - - /// Returns all gate indices touching the given qubit. - #[inline] - #[must_use] - pub fn gates_touching_qubit_raw(&self, qubit: usize) -> &[u32] { - if qubit < self.qubit_to_gates.len() { - &self.qubit_to_gates[qubit] - } else { - &[] - } - } - - /// Returns all gates touching the given qubit (`GateId` version). - #[inline] - #[must_use] - pub fn gates_touching_qubit(&self, _qubit: usize) -> &[GateId] { - // Note: This is a bit of a hack - we're reinterpreting u32 as GateId - // In practice, for read-only circuits without removal, generation is always 0 - &[] // Return empty - use gates_touching_qubit_raw instead - } - - /// Returns gate indices in a specific tick. - #[inline] - #[must_use] - pub fn gates_in_tick(&self, tick: usize) -> &[u32] { - if tick < self.tick_gates.len() { - &self.tick_gates[tick] - } else { - &[] - } - } - - /// Returns gates on a qubit sorted by tick (for backward traversal). - #[inline] - #[must_use] - pub fn qubit_gates_sorted(&self, qubit: usize) -> &[(u16, u32)] { - if qubit < self.qubit_gates_by_tick.len() { - &self.qubit_gates_by_tick[qubit] - } else { - &[] - } - } - - /// Sorts the `qubit_gates_by_tick` for each qubit (call after building). - pub fn finalize(&mut self) { - for gates in &mut self.qubit_gates_by_tick { - gates.sort_by_key(|&(tick, _)| tick); - } - } - - /// Clears all indexes. - pub fn clear(&mut self) { - self.tick_gates.clear(); - self.qubit_to_gates.clear(); - self.qubit_gates_by_tick.clear(); - self.max_qubit = 0; - self.num_ticks = 0; - } - - /// Rebuilds indexes from gate storage. - pub fn rebuild(&mut self, storage: &GateStorage) { - self.clear(); - - for idx in 0..storage.slot_count() { - if storage.is_occupied(idx) { - let tick_id = storage.tick_id_unchecked(idx); - let qubits = storage.qubits_unchecked(idx); - #[allow(clippy::cast_possible_truncation)] // gate index fits in u32 - self.register_gate_raw(idx as u32, tick_id, qubits); - } - } - - self.finalize(); - } -} - -// ============================================================================ -// Metadata Storage -// ============================================================================ - -/// Lazy metadata storage - only allocates when metadata is actually used. -#[derive(Debug, Clone, Default)] -pub struct MetadataStorage { - /// Per-gate attributes. - pub gate_attrs: BTreeMap>, - /// Per-tick attributes. - pub tick_attrs: Vec>, - /// Circuit-level attributes. - pub circuit_attrs: BTreeMap, -} - -impl MetadataStorage { - /// Creates empty metadata storage. - #[must_use] - pub fn new() -> Self { - Self::default() - } - - /// Sets a gate attribute. - pub fn set_gate_attr(&mut self, gate_id: GateId, key: &str, value: Attribute) { - self.gate_attrs - .entry(gate_id) - .or_default() - .insert(key.to_string(), value); - } - - /// Gets a gate attribute. - #[must_use] - pub fn get_gate_attr(&self, gate_id: GateId, key: &str) -> Option<&Attribute> { - self.gate_attrs.get(&gate_id).and_then(|m| m.get(key)) - } - - /// Sets a tick attribute. - pub fn set_tick_attr(&mut self, tick: usize, key: &str, value: Attribute) { - if tick >= self.tick_attrs.len() { - self.tick_attrs.resize(tick + 1, BTreeMap::new()); - } - self.tick_attrs[tick].insert(key.to_string(), value); - } - - /// Gets a tick attribute. - #[must_use] - pub fn get_tick_attr(&self, tick: usize, key: &str) -> Option<&Attribute> { - self.tick_attrs.get(tick).and_then(|m| m.get(key)) - } - - /// Sets a circuit attribute. - pub fn set_circuit_attr(&mut self, key: &str, value: Attribute) { - self.circuit_attrs.insert(key.to_string(), value); - } - - /// Gets a circuit attribute. - #[must_use] - pub fn get_circuit_attr(&self, key: &str) -> Option<&Attribute> { - self.circuit_attrs.get(key) - } - - /// Clears all metadata. - pub fn clear(&mut self) { - self.gate_attrs.clear(); - self.tick_attrs.clear(); - self.circuit_attrs.clear(); - } -} - -fn normalized_attrs( - gate_attrs: &BTreeMap>, - gate_id: GateId, -) -> Option<&BTreeMap> { - gate_attrs.get(&gate_id).filter(|attrs| !attrs.is_empty()) -} - -// ============================================================================ -// TickCircuitSoA -// ============================================================================ - -/// A tick-based quantum circuit optimized for batched simulation. -/// -/// This is a DOD (Data-Oriented Design) alternative to [`TickCircuit`](crate::TickCircuit) -/// that provides: -/// - **Batched simulation**: Gates grouped by type for efficient batch execution -/// - **Cache-friendly access**: Qubits for same-type gates stored contiguously -/// - **Individual gate access**: `SoA` storage for analysis workloads -#[derive(Debug, Clone, Default)] -pub struct TickCircuitSoA { - /// Gates grouped by type for batched simulation (primary interface). - pub batched: TickGateGroups, - /// Gate data in `SoA` layout (for individual gate access). - pub storage: GateStorage, - /// Pre-computed indexes. - pub indexes: CircuitIndexes, - /// Metadata (lazy allocation). - pub metadata: MetadataStorage, -} - -impl TickCircuitSoA { - /// Creates a new empty circuit. - #[must_use] - pub fn new() -> Self { - Self::default() - } - - /// Creates a builder for constructing circuits with a fluent API. - #[must_use] - pub fn builder() -> TickCircuitSoABuilder { - TickCircuitSoABuilder::new() - } - - /// Returns the number of ticks. - #[inline] - #[must_use] - pub fn num_ticks(&self) -> usize { - self.indexes.num_ticks - } - - /// Returns the total number of active gates. - #[inline] - #[must_use] - pub fn gate_count(&self) -> usize { - self.storage.active_gate_count() - } - - /// Returns the number of compatible gate batches across all ticks. - /// - /// This is a representation-level batch count: gates share a batch only - /// when they are identical except for disjoint qubits and have equivalent - /// per-gate metadata. - #[must_use] - pub fn gate_batch_count(&self) -> usize { - let mut total = 0; - - for tick in 0..self.indexes.num_ticks { - let mut representative_indices: Vec = Vec::new(); - - 'gate: for &gate_idx in self.indexes.gates_in_tick(tick) { - if !self.storage.is_occupied(gate_idx as usize) { - continue; - } - let gate = self.storage.gate_from_index(gate_idx as usize); - let gate_id = GateId::new(gate_idx, self.storage.generations[gate_idx as usize]); - - for &rep_idx in &representative_indices { - let rep_gate = self.storage.gate_from_index(rep_idx as usize); - let rep_id = GateId::new(rep_idx, self.storage.generations[rep_idx as usize]); - if normalized_attrs(&self.metadata.gate_attrs, rep_id) - == normalized_attrs(&self.metadata.gate_attrs, gate_id) - && rep_gate.can_batch_with(&gate) - { - continue 'gate; - } - } - - representative_indices.push(gate_idx); - } - - total += representative_indices.len(); - } - - total - } - - /// Returns the maximum qubit index. - #[inline] - #[must_use] - pub fn max_qubit(&self) -> usize { - self.indexes.max_qubit - } - - /// Returns the gate type for a gate ID. - #[inline] - #[must_use] - pub fn gate_type(&self, id: GateId) -> Option { - self.storage.gate_type(id) - } - - /// Returns the qubits for a gate ID. - #[inline] - #[must_use] - pub fn gate_qubits(&self, id: GateId) -> Option<&[QubitId]> { - self.storage.gate_qubits(id) - } - - /// Returns the angles for a gate ID. - #[inline] - #[must_use] - pub fn gate_angles(&self, id: GateId) -> Option<&[Angle64]> { - self.storage.gate_angles(id) - } - - /// Returns all gates touching a specific qubit. - #[inline] - #[must_use] - pub fn gates_touching_qubit(&self, qubit: usize) -> &[GateId] { - self.indexes.gates_touching_qubit(qubit) - } - - /// Returns all gate indices touching a specific qubit (optimized, no validation). - #[inline] - #[must_use] - pub fn gates_touching_qubit_raw(&self, qubit: usize) -> &[u32] { - self.indexes.gates_touching_qubit_raw(qubit) - } - - /// Returns gate indices in a specific tick (optimized, O(1)). - #[inline] - #[must_use] - pub fn gates_in_tick_raw(&self, tick: usize) -> &[u32] { - self.indexes.gates_in_tick(tick) - } - - /// Returns gates on a qubit sorted by tick (for backward traversal). - #[inline] - #[must_use] - pub fn qubit_gates_sorted(&self, qubit: usize) -> &[(u16, u32)] { - self.indexes.qubit_gates_sorted(qubit) - } - - /// Validates that a gate ID is still valid. - #[inline] - #[must_use] - pub fn is_valid(&self, id: GateId) -> bool { - self.storage.is_valid(id) - } - - /// Iterator over all valid gate IDs. - pub fn iter_gate_ids(&self) -> impl Iterator + '_ { - self.storage.iter_ids() - } - - /// Iterator over gate IDs in a specific tick. - #[allow(clippy::cast_possible_truncation)] // tick index fits in u16 - pub fn gates_in_tick(&self, tick: usize) -> impl Iterator + '_ { - self.storage - .iter_ids() - .filter(move |&id| self.storage.tick_id(id) == Some(tick as u16)) - } - - // ========================================================================= - // Batched Simulation API - // ========================================================================= - - /// Returns an iterator over ticks with batched gates for simulation. - /// - /// This is the primary API for efficient circuit simulation: - /// ```text - /// for (tick_idx, tick) in circuit.iter_ticks_batched() { - /// for batch in tick.iter() { - /// match batch.gate_type { - /// GateType::H => sim.h(batch.qubits()), - /// GateType::CX => sim.cx(batch.qubits()), - /// // ... - /// } - /// } - /// } - /// ``` - #[inline] - pub fn iter_ticks_batched(&self) -> impl Iterator { - self.batched.iter_ticks() - } - - /// Returns the batched gates for a specific tick. - #[inline] - #[must_use] - pub fn tick_batched(&self, tick: usize) -> Option<&TickBatches> { - self.batched.tick(tick) - } - - /// Returns the number of ticks (from batched representation). - #[inline] - #[must_use] - pub fn num_ticks_batched(&self) -> usize { - self.batched.num_ticks() - } - - /// Clears the circuit. - pub fn clear(&mut self) { - self.batched.clear(); - self.storage.clear(); - self.indexes.clear(); - self.metadata.clear(); - } - - /// Rebuilds indexes after modifications. - pub fn rebuild_indexes(&mut self) { - self.indexes.rebuild(&self.storage); - } -} - -// ============================================================================ -// Builder Pattern -// ============================================================================ - -/// Builder for constructing `TickCircuitSoA` with a fluent API. -#[derive(Debug)] -pub struct TickCircuitSoABuilder { - batched: TickGateGroups, - storage: GateStorage, - indexes: CircuitIndexes, - metadata: MetadataStorage, - current_tick: u16, - last_gate_id: Option, -} - -impl TickCircuitSoABuilder { - /// Creates a new builder. - #[must_use] - pub fn new() -> Self { - Self { - batched: TickGateGroups::new(), - storage: GateStorage::new(), - indexes: CircuitIndexes::new(), - metadata: MetadataStorage::new(), - current_tick: 0, - last_gate_id: None, - } - } - - /// Starts a new tick. - pub fn tick(&mut self) -> &mut Self { - // Update num_ticks - self.indexes.num_ticks = (self.current_tick + 1) as usize; - self.current_tick += 1; - self.last_gate_id = None; - self - } - - /// Adds a gate to the current tick. - fn add_gate( - &mut self, - gate_type: GateType, - qubits: &[QubitId], - angles: &[Angle64], - params: &[f64], - ) -> &mut Self { - let tick = self.current_tick.saturating_sub(1); - - // Add to batched representation (primary for simulation) - self.batched - .add_gate(tick as usize, gate_type, qubits, angles); - - // Add to SoA storage (for individual gate access) - let gate_id = self - .storage - .add_gate(gate_type, tick, qubits, angles, params); - - // Update indexes - self.indexes.register_gate_raw(gate_id.index, tick, qubits); - self.last_gate_id = Some(gate_id); - self - } - - /// Sets metadata on the last added gate (or tick if no gate yet). - pub fn meta(&mut self, key: &str, value: impl Into) -> &mut Self { - if let Some(gate_id) = self.last_gate_id { - self.metadata.set_gate_attr(gate_id, key, value.into()); - } else { - // Set tick-level metadata - let tick = self.current_tick.saturating_sub(1) as usize; - self.metadata.set_tick_attr(tick, key, value.into()); - } - self - } - - /// Builds the final circuit. - #[must_use] - pub fn build(mut self) -> TickCircuitSoA { - // Finalize indexes (sort qubit gates by tick for efficient traversal) - self.indexes.finalize(); - TickCircuitSoA { - batched: self.batched, - storage: self.storage, - indexes: self.indexes, - metadata: self.metadata, - } - } - - // ========================================================================= - // Gate methods (mirror TickHandle API) - // ========================================================================= - - /// Apply Hadamard gate(s). - pub fn h(&mut self, qubits: &[impl Into + Copy]) -> &mut Self { - let qs: Vec = qubits.iter().map(|&q| q.into()).collect(); - self.add_gate(GateType::H, &qs, &[], &[]) - } - - /// Apply X gate(s). - pub fn x(&mut self, qubits: &[impl Into + Copy]) -> &mut Self { - let qs: Vec = qubits.iter().map(|&q| q.into()).collect(); - self.add_gate(GateType::X, &qs, &[], &[]) - } - - /// Apply Y gate(s). - pub fn y(&mut self, qubits: &[impl Into + Copy]) -> &mut Self { - let qs: Vec = qubits.iter().map(|&q| q.into()).collect(); - self.add_gate(GateType::Y, &qs, &[], &[]) - } - - /// Apply Z gate(s). - pub fn z(&mut self, qubits: &[impl Into + Copy]) -> &mut Self { - let qs: Vec = qubits.iter().map(|&q| q.into()).collect(); - self.add_gate(GateType::Z, &qs, &[], &[]) - } - - /// Apply SX gate(s). - pub fn sx(&mut self, qubits: &[impl Into + Copy]) -> &mut Self { - let qs: Vec = qubits.iter().map(|&q| q.into()).collect(); - self.add_gate(GateType::SX, &qs, &[], &[]) - } - - /// Apply SY gate(s). - pub fn sy(&mut self, qubits: &[impl Into + Copy]) -> &mut Self { - let qs: Vec = qubits.iter().map(|&q| q.into()).collect(); - self.add_gate(GateType::SY, &qs, &[], &[]) - } - - /// Apply SZ gate(s). - pub fn sz(&mut self, qubits: &[impl Into + Copy]) -> &mut Self { - let qs: Vec = qubits.iter().map(|&q| q.into()).collect(); - self.add_gate(GateType::SZ, &qs, &[], &[]) - } - - /// Apply CX gate(s). - pub fn cx( - &mut self, - pairs: &[(impl Into + Copy, impl Into + Copy)], - ) -> &mut Self { - let qs: Vec = pairs - .iter() - .flat_map(|&(c, t)| [c.into(), t.into()]) - .collect(); - self.add_gate(GateType::CX, &qs, &[], &[]) - } - - /// Apply CZ gate(s). - pub fn cz( - &mut self, - pairs: &[(impl Into + Copy, impl Into + Copy)], - ) -> &mut Self { - let qs: Vec = pairs - .iter() - .flat_map(|&(a, b)| [a.into(), b.into()]) - .collect(); - self.add_gate(GateType::CZ, &qs, &[], &[]) - } - - /// Prepare qubit(s) in |0⟩. - pub fn pz(&mut self, qubits: &[impl Into + Copy]) -> &mut Self { - let qs: Vec = qubits.iter().map(|&q| q.into()).collect(); - self.add_gate(GateType::PZ, &qs, &[], &[]) - } - - /// Measure qubit(s) in Z basis. - pub fn mz(&mut self, qubits: &[impl Into + Copy]) -> &mut Self { - let qs: Vec = qubits.iter().map(|&q| q.into()).collect(); - self.add_gate(GateType::MZ, &qs, &[], &[]) - } -} - -impl Default for TickCircuitSoABuilder { - fn default() -> Self { - Self::new() - } -} - -// ============================================================================ -// Conversion from TickCircuit -// ============================================================================ - -impl From<&crate::TickCircuit> for TickCircuitSoA { - fn from(tc: &crate::TickCircuit) -> Self { - let mut builder = TickCircuitSoABuilder::new(); - - for (tick_idx, tick_data) in tc.iter_ticks() { - // Ensure we're at the right tick - #[allow(clippy::cast_possible_truncation)] // tick index fits in u16 - while builder.current_tick <= tick_idx as u16 { - builder.tick(); - } - - for (gate_idx, gate) in tick_data.gates().iter().enumerate() { - let qubits: Vec = gate.qubits.to_vec(); - let angles: Vec = gate.angles.to_vec(); - let params: Vec = gate.params.to_vec(); - - let tick_num = builder.current_tick.saturating_sub(1); - - // Add to batched representation (primary for simulation) - builder - .batched - .add_gate(tick_num as usize, gate.gate_type, &qubits, &angles); - - // Add to SoA storage (for individual gate access) - let gate_id = - builder - .storage - .add_gate(gate.gate_type, tick_num, &qubits, &angles, ¶ms); - builder - .indexes - .register_gate_raw(gate_id.index, tick_num, &qubits); - - // Copy gate attributes - for (key, value) in tick_data.gate_attrs(gate_idx) { - builder.metadata.set_gate_attr(gate_id, key, value.clone()); - } - } - - // Copy tick attributes - for (key, value) in tick_data.tick_attrs() { - builder.metadata.set_tick_attr(tick_idx, key, value.clone()); - } - } - - // Copy circuit attributes - for (key, value) in tc.circuit_attrs() { - builder.metadata.set_circuit_attr(key, value.clone()); - } - - builder.build() - } -} - -#[cfg(test)] -mod tests { - use super::*; - - #[test] - fn test_basic_construction() { - let mut builder = TickCircuitSoA::builder(); - builder - .tick() - .pz(&[0, 1]) - .tick() - .h(&[0]) - .cx(&[(0, 1)]) - .tick() - .mz(&[0, 1]); - - let circuit = builder.build(); - - assert_eq!(circuit.num_ticks(), 3); - assert_eq!(circuit.gate_count(), 6); // 2 PZ, 1 H, 1 CX, 2 MZ - } - - #[test] - fn test_gate_lookup() { - let mut builder = TickCircuitSoA::builder(); - builder.tick().h(&[0]).x(&[1]); - - let circuit = builder.build(); - - // Find all gates - let gate_ids: Vec<_> = circuit.iter_gate_ids().collect(); - assert_eq!(gate_ids.len(), 2); - - // Check gate types - assert_eq!(circuit.gate_type(gate_ids[0]), Some(GateType::H)); - assert_eq!(circuit.gate_type(gate_ids[1]), Some(GateType::X)); - - // Check qubits - assert_eq!( - circuit.gate_qubits(gate_ids[0]), - Some([QubitId::from(0)].as_slice()) - ); - assert_eq!( - circuit.gate_qubits(gate_ids[1]), - Some([QubitId::from(1)].as_slice()) - ); - } - - #[test] - fn test_qubit_index() { - let mut builder = TickCircuitSoA::builder(); - builder.tick().h(&[0]).x(&[1]).tick().cx(&[(0, 1)]); - - let circuit = builder.build(); - - // Gates on qubit 0: H and CX (using raw accessor for efficiency) - let q0_gates = circuit.gates_touching_qubit_raw(0); - assert_eq!(q0_gates.len(), 2); - - // Gates on qubit 1: X and CX - let q1_gates = circuit.gates_touching_qubit_raw(1); - assert_eq!(q1_gates.len(), 2); - - // Gates on qubit 2: none - let q2_gates = circuit.gates_touching_qubit_raw(2); - assert_eq!(q2_gates.len(), 0); - } - - #[test] - fn test_metadata() { - let mut builder = TickCircuitSoA::builder(); - builder - .tick() - .meta("round", Attribute::Int(0)) - .h(&[0]) - .meta("duration", Attribute::Float(50.0)); - - let circuit = builder.build(); - - // Check tick metadata - assert_eq!( - circuit.metadata.get_tick_attr(0, "round"), - Some(&Attribute::Int(0)) - ); - - // Check gate metadata - let gate_ids: Vec<_> = circuit.iter_gate_ids().collect(); - assert_eq!( - circuit.metadata.get_gate_attr(gate_ids[0], "duration"), - Some(&Attribute::Float(50.0)) - ); - } - - #[test] - fn test_gate_removal() { - let mut builder = TickCircuitSoA::builder(); - builder.tick().h(&[0]).x(&[1]); - - let mut circuit = builder.build(); - let gate_ids: Vec<_> = circuit.iter_gate_ids().collect(); - - assert_eq!(circuit.gate_count(), 2); - - // Remove first gate - assert!(circuit.storage.remove(gate_ids[0])); - assert_eq!(circuit.gate_count(), 1); - - // Gate ID is now invalid - assert!(!circuit.is_valid(gate_ids[0])); - assert!(circuit.is_valid(gate_ids[1])); - } - - #[test] - fn test_generational_ids() { - let mut storage = GateStorage::new(); - - // Add and remove a gate - let id1 = storage.add_gate(GateType::H, 0, &[QubitId::from(0)], &[], &[]); - assert!(storage.is_valid(id1)); - - storage.remove(id1); - assert!(!storage.is_valid(id1)); - - // Add another gate - reuses the slot with new generation - let id2 = storage.add_gate(GateType::X, 0, &[QubitId::from(0)], &[], &[]); - assert!(storage.is_valid(id2)); - assert!(!storage.is_valid(id1)); // Old ID still invalid - - // Same index, different generation - assert_eq!(id1.index(), id2.index()); - assert_ne!(id1.generation(), id2.generation()); - } - - #[test] - fn test_batched_simulation_api() { - let mut builder = TickCircuitSoA::builder(); - builder - .tick() - .pz(&[0, 1, 2, 3]) // 4 preps - .tick() - .h(&[0, 1]) // 2 H gates - .x(&[2, 3]) // 2 X gates - .tick() - .cx(&[(0, 1), (2, 3)]) // 2 CX gates - .tick() - .mz(&[0, 1, 2, 3]); // 4 measurements - - let circuit = builder.build(); - - // Check tick count - assert_eq!(circuit.num_ticks_batched(), 4); - assert_eq!(circuit.gate_count(), 14); - assert_eq!(circuit.gate_batch_count(), 5); - - // Check tick 0: preps batched together - let tick0 = circuit.tick_batched(0).unwrap(); - assert_eq!(tick0.batch_count(), 1); - let prep_batch = tick0.batch_for_type(GateType::PZ).unwrap(); - assert_eq!(prep_batch.qubits().len(), 4); - assert_eq!(prep_batch.gate_count(), 4); - - // Check tick 1: H and X are separate batches - let tick1 = circuit.tick_batched(1).unwrap(); - assert_eq!(tick1.batch_count(), 2); - let h_batch = tick1.batch_for_type(GateType::H).unwrap(); - assert_eq!(h_batch.qubits().len(), 2); - let x_batch = tick1.batch_for_type(GateType::X).unwrap(); - assert_eq!(x_batch.qubits().len(), 2); - - // Check tick 2: CX gates batched - let tick2 = circuit.tick_batched(2).unwrap(); - assert_eq!(tick2.batch_count(), 1); - let cx_batch = tick2.batch_for_type(GateType::CX).unwrap(); - assert_eq!(cx_batch.qubits().len(), 4); // 2 pairs = 4 qubits - assert_eq!(cx_batch.gate_count(), 2); - - // Check tick 3: measurements batched - let tick3 = circuit.tick_batched(3).unwrap(); - assert_eq!(tick3.batch_count(), 1); - let mz_batch = tick3.batch_for_type(GateType::MZ).unwrap(); - assert_eq!(mz_batch.qubits().len(), 4); - assert_eq!(mz_batch.gate_count(), 4); - } - - #[test] - fn test_gate_batch_count_respects_metadata() { - let mut same = crate::TickCircuit::new(); - { - let mut tick = same.tick(); - tick.h(&[0]) - .meta("calibration", Attribute::String("a".into())); - tick.h(&[1]) - .meta("calibration", Attribute::String("a".into())); - } - let same_soa = TickCircuitSoA::from(&same); - assert_eq!(same_soa.gate_count(), 2); - assert_eq!(same_soa.gate_batch_count(), 1); - - let mut different = crate::TickCircuit::new(); - { - let mut tick = different.tick(); - tick.h(&[0]) - .meta("calibration", Attribute::String("a".into())); - tick.h(&[1]) - .meta("calibration", Attribute::String("b".into())); - } - let different_soa = TickCircuitSoA::from(&different); - assert_eq!(different_soa.gate_count(), 2); - assert_eq!(different_soa.gate_batch_count(), 2); - } - - #[test] - fn test_iter_ticks_batched() { - let mut builder = TickCircuitSoA::builder(); - builder.tick().h(&[0, 1, 2]).tick().cx(&[(0, 1)]); - - let circuit = builder.build(); - - // Iterate and count - let mut tick_count = 0; - let mut total_batches = 0; - for (_tick_idx, tick) in circuit.iter_ticks_batched() { - tick_count += 1; - total_batches += tick.batch_count(); - } - - assert_eq!(tick_count, 2); - assert_eq!(total_batches, 2); // H batch + CX batch - } -} diff --git a/crates/pecos-simulators/src/circuit_executor.rs b/crates/pecos-simulators/src/circuit_executor.rs index 460fb6941..e4cf66735 100644 --- a/crates/pecos-simulators/src/circuit_executor.rs +++ b/crates/pecos-simulators/src/circuit_executor.rs @@ -43,7 +43,7 @@ use crate::{CliffordGateable, MeasurementResult}; use pecos_core::gate_type::GateType; use pecos_core::{Gate, QubitId}; -use pecos_quantum::{GateBatch, TickCircuit, TickGateGroups}; +use pecos_quantum::TickCircuit; use smallvec::SmallVec; /// Convert a flat qubit slice `[c0, t0, c1, t1, ...]` to a vec of pairs. @@ -99,126 +99,6 @@ impl<'a> CircuitExecutor<'a> { } } -/// Executes a `TickGateGroups` directly on a simulator. -/// -/// This is a simpler interface when you have gate groups but not the full circuit. -pub fn execute_batched( - groups: &TickGateGroups, - sim: &mut S, -) -> Vec { - let mut measurements = Vec::new(); - - for (_tick_idx, tick) in groups.iter_ticks() { - for batch in tick.iter() { - execute_single_batch(sim, batch, &mut measurements); - } - } - - measurements -} - -/// Executes a single batch on a simulator. -#[inline] -fn execute_single_batch( - sim: &mut S, - batch: &GateBatch, - measurements: &mut Vec, -) { - let qubits = batch.qubits(); - - match batch.gate_type { - GateType::I => { - sim.identity(qubits); - } - GateType::X => { - sim.x(qubits); - } - GateType::Y => { - sim.y(qubits); - } - GateType::Z => { - sim.z(qubits); - } - GateType::H => { - sim.h(qubits); - } - GateType::F => { - sim.f(qubits); - } - GateType::Fdg => { - sim.fdg(qubits); - } - GateType::SX => { - sim.sx(qubits); - } - GateType::SXdg => { - sim.sxdg(qubits); - } - GateType::SY => { - sim.sy(qubits); - } - GateType::SYdg => { - sim.sydg(qubits); - } - GateType::SZ => { - sim.sz(qubits); - } - GateType::SZdg => { - sim.szdg(qubits); - } - GateType::CX => { - let pairs = flat_to_pairs(qubits); - sim.cx(&pairs); - } - GateType::CY => { - let pairs = flat_to_pairs(qubits); - sim.cy(&pairs); - } - GateType::CZ => { - let pairs = flat_to_pairs(qubits); - sim.cz(&pairs); - } - GateType::SXX => { - let pairs = flat_to_pairs(qubits); - sim.sxx(&pairs); - } - GateType::SXXdg => { - let pairs = flat_to_pairs(qubits); - sim.sxxdg(&pairs); - } - GateType::SYY => { - let pairs = flat_to_pairs(qubits); - sim.syy(&pairs); - } - GateType::SYYdg => { - let pairs = flat_to_pairs(qubits); - sim.syydg(&pairs); - } - GateType::SZZ => { - let pairs = flat_to_pairs(qubits); - sim.szz(&pairs); - } - GateType::SZZdg => { - let pairs = flat_to_pairs(qubits); - sim.szzdg(&pairs); - } - GateType::SWAP => { - let pairs = flat_to_pairs(qubits); - sim.swap(&pairs); - } - GateType::PZ | GateType::QAlloc => { - sim.pz(qubits); - } - GateType::MZ | GateType::MeasureFree => { - measurements.extend(sim.mz(qubits)); - } - GateType::Idle => {} - other => { - panic!("Unsupported gate type in circuit executor: {other:?}"); - } - } -} - /// Executes one full-fidelity `TickCircuit` gate command on a simulator. #[inline] fn execute_gate_command( @@ -378,7 +258,7 @@ impl GateSystemRegistry { mod tests { use super::*; use crate::SparseStab; - use pecos_quantum::{TickCircuit, TickCircuitSoA}; + use pecos_quantum::TickCircuit; #[test] fn test_circuit_executor_basic() { @@ -412,23 +292,4 @@ mod tests { // Should have 4 measurements assert_eq!(measurements.len(), 4); } - - #[test] - fn test_execute_batched_function() { - let mut builder = TickCircuitSoA::builder(); - builder - .tick() - .pz(&[0, 1]) - .tick() - .h(&[0, 1]) - .tick() - .mz(&[0, 1]); - - let circuit = builder.build(); - - let mut sim = SparseStab::new(2); - let measurements = execute_batched(&circuit.batched, &mut sim); - - assert_eq!(measurements.len(), 2); - } } diff --git a/crates/pecos-simulators/src/lib.rs b/crates/pecos-simulators/src/lib.rs index 4ffe87828..88791d4bd 100644 --- a/crates/pecos-simulators/src/lib.rs +++ b/crates/pecos-simulators/src/lib.rs @@ -62,7 +62,7 @@ pub use arbitrary_rotation_gateable::ArbitraryRotationGateable; pub use batched_ops::{BatchedOps, CommandBuffer, RawOps}; #[doc(hidden)] pub use bitmask_pauli_prop::BitmaskPauliProp; -pub use circuit_executor::{CircuitExecutor, GateSystem, GateSystemRegistry, execute_batched}; +pub use circuit_executor::{CircuitExecutor, GateSystem, GateSystemRegistry}; pub use clifford_gateable::{CliffordGateable, MeasurementResult}; pub use coin_toss::CoinToss; /// Sparse index representation of stabilizer/destabilizer generators. From fb5e069e5abae449a122b2cfe6978f4371c7ab86 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 11:42:02 -0600 Subject: [PATCH 103/125] Rename tick analyzer to batched --- crates/pecos-qec/src/fault_tolerance/propagator.rs | 4 ++-- .../propagator/{tick_soa.rs => tick_batched.rs} | 14 +++++++------- 2 files changed, 9 insertions(+), 9 deletions(-) rename crates/pecos-qec/src/fault_tolerance/propagator/{tick_soa.rs => tick_batched.rs} (98%) diff --git a/crates/pecos-qec/src/fault_tolerance/propagator.rs b/crates/pecos-qec/src/fault_tolerance/propagator.rs index 5bee37eeb..aea82a9f6 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator.rs @@ -97,7 +97,7 @@ mod checker; pub mod dag; mod pauli; mod tick; -mod tick_soa; +mod tick_batched; pub mod types; // Re-export from submodules @@ -113,7 +113,7 @@ pub use pauli::{ propagate_tick_range, }; pub use tick::TickFaultAnalyzer; -pub use tick_soa::TickFaultAnalyzerSoA; +pub use tick_batched::TickFaultAnalyzerBatched; pub use types::{ DemOutputIdx, DetectorId, DetectorIdx, FaultInfluence, FaultInfluenceMap, LocationId, MeasurementId, NodeId, Pauli, TrackedOpId, TrackedOpIdx, diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/tick_soa.rs b/crates/pecos-qec/src/fault_tolerance/propagator/tick_batched.rs similarity index 98% rename from crates/pecos-qec/src/fault_tolerance/propagator/tick_soa.rs rename to crates/pecos-qec/src/fault_tolerance/propagator/tick_batched.rs index 43047bead..3884d8e95 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/tick_soa.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/tick_batched.rs @@ -1,6 +1,6 @@ //! Optimized tick fault analyzer using batched `TickCircuit` access. //! -//! This module provides [`TickFaultAnalyzerSoA`] which uses the batched +//! This module provides [`TickFaultAnalyzerBatched`] which uses the batched //! full-fidelity command view of [`TickCircuit`] for cache-efficient fault //! analysis without requiring a converted circuit representation. //! @@ -62,7 +62,7 @@ impl AnalyzerWorkBuffers { } // ============================================================================ -// Optimized SOA-Based Fault Analyzer +// Optimized Batched Tick Fault Analyzer // ============================================================================ #[derive(Debug, Clone)] @@ -75,7 +75,7 @@ struct AnalyzerGate { /// Optimized fault analyzer for `TickCircuit`. /// /// Uses raw indices and bitsets for minimal overhead in hot paths. -pub struct TickFaultAnalyzerSoA<'a> { +pub struct TickFaultAnalyzerBatched<'a> { circuit: &'a TickCircuit, /// Flattened full-fidelity gate command view. gates: Vec, @@ -89,7 +89,7 @@ pub struct TickFaultAnalyzerSoA<'a> { tick_locations: Vec>, } -impl<'a> TickFaultAnalyzerSoA<'a> { +impl<'a> TickFaultAnalyzerBatched<'a> { /// Creates a new analyzer for the given circuit. #[must_use] pub fn new(circuit: &'a TickCircuit) -> Self { @@ -724,7 +724,7 @@ mod tests { circuit.tick().h(&[0]); circuit.tick().cx(&[(0, 1)]); circuit.tick().mz(&[0, 1]); - let analyzer = TickFaultAnalyzerSoA::new(&circuit); + let analyzer = TickFaultAnalyzerBatched::new(&circuit); assert!(!analyzer.locations().is_empty()); @@ -741,7 +741,7 @@ mod tests { circuit.tick().h(&[0]).h(&[2]); circuit.tick().cx(&[(0, 1)]).cx(&[(2, 3)]); circuit.tick().mz(&[0, 1, 2, 3]); - let analyzer = TickFaultAnalyzerSoA::new(&circuit); + let analyzer = TickFaultAnalyzerBatched::new(&circuit); let map = analyzer.build_influence_map(); @@ -756,7 +756,7 @@ mod tests { circuit.tick().h(&[0]); circuit.tick().cx(&[(0, 1)]); circuit.tick().mz(&[0, 1]); - let analyzer = TickFaultAnalyzerSoA::new(&circuit); + let analyzer = TickFaultAnalyzerBatched::new(&circuit); let tracked_ops = [(&[] as &[usize], &[1usize] as &[usize])]; let map = analyzer.build_influence_map_with_tracked_ops(&tracked_ops); From e8f38dc52d5cfbc84e6f2db114daf923e44e5b66 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 11:45:42 -0600 Subject: [PATCH 104/125] Clarify Tick internal batched command storage --- crates/pecos-quantum/src/tick_circuit.rs | 236 ++++++++++++++--------- 1 file changed, 140 insertions(+), 96 deletions(-) diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index 6f774a052..6deed9cbf 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -328,9 +328,9 @@ impl From for CustomGateError { /// A single time slice containing gates that execute in parallel. #[derive(Debug, Clone, Default)] pub struct Tick { - /// Gates in this tick (all act on disjoint qubits). - gates: Vec, - /// Metadata for each gate, indexed by position in `gates`. + /// Gate batches in this tick (all act on disjoint qubits). + gate_batches: Vec, + /// Metadata for each gate batch, indexed by position in `gate_batches`. gate_attrs: BTreeMap>, /// Tick-level metadata. attrs: BTreeMap, @@ -358,13 +358,13 @@ impl Tick { /// `cx(&[(0, 1), (2, 3)])` count as one stored command. #[must_use] pub fn len(&self) -> usize { - self.gates.len() + self.gate_batches.len() } /// Get the number of individual gates in this tick. #[must_use] pub fn gate_count(&self) -> usize { - self.gates.iter().map(Gate::num_gates).sum() + self.gate_batches.iter().map(Gate::num_gates).sum() } /// Get the number of compatible gate batches in this tick. @@ -374,10 +374,10 @@ impl Tick { #[must_use] pub fn gate_batch_count(&self) -> usize { let mut representative_indices: Vec = Vec::new(); - 'gate: for (idx, gate) in self.gates.iter().enumerate() { + 'gate: for (idx, gate) in self.gate_batches.iter().enumerate() { for &rep_idx in &representative_indices { if self.gate_attrs_equivalent(rep_idx, idx) - && self.gates[rep_idx].can_batch_with(gate) + && self.gate_batches[rep_idx].can_batch_with(gate) { continue 'gate; } @@ -390,13 +390,13 @@ impl Tick { /// Check if the tick is empty. #[must_use] pub fn is_empty(&self) -> bool { - self.gates.is_empty() + self.gate_batches.is_empty() } /// Get the gates in this tick. #[must_use] pub fn gates(&self) -> &[Gate] { - &self.gates + &self.gate_batches } /// Get the full-fidelity gate batches in this tick. @@ -411,12 +411,12 @@ impl Tick { /// view cheaper or more data-oriented without changing consumers. #[must_use] pub fn gate_batches(&self) -> &[Gate] { - &self.gates + &self.gate_batches } /// Get mutable access to the gates in this tick. pub fn gates_mut(&mut self) -> &mut [Gate] { - &mut self.gates + &mut self.gate_batches } /// Add a gate to this tick. @@ -432,8 +432,8 @@ impl Tick { } fn push_gate_unchecked(&mut self, gate: Gate) -> usize { - let idx = self.gates.len(); - self.gates.push(gate); + let idx = self.gate_batches.len(); + self.gate_batches.push(gate); idx } @@ -465,7 +465,7 @@ impl Tick { } fn compatible_empty_attr_batch(&self, gate: &Gate) -> Option { - self.gates + self.gate_batches .iter() .enumerate() .find(|(idx, existing)| self.gate_has_no_attrs(*idx) && existing.can_batch_with(gate)) @@ -473,7 +473,7 @@ impl Tick { } fn whole_gate_piece(&self, gate_idx: usize) -> GateBatchPiece { - let gate = &self.gates[gate_idx]; + let gate = &self.gate_batches[gate_idx]; GateBatchPiece { gate_idx, qubit_start: 0, @@ -484,21 +484,21 @@ impl Tick { } fn merge_compatible_piece_at(&mut self, piece: GateBatchPiece) -> GateBatchPiece { - if piece.gate_idx >= self.gates.len() { + if piece.gate_idx >= self.gate_batches.len() { return piece; } let Some(target_idx) = (0..piece.gate_idx).find(|&idx| { self.gate_attrs_equivalent(idx, piece.gate_idx) - && self.gates[idx].can_batch_with(&self.gates[piece.gate_idx]) + && self.gate_batches[idx].can_batch_with(&self.gate_batches[piece.gate_idx]) }) else { return piece; }; - let qubit_start = self.gates[target_idx].qubits.len(); - let meas_id_start = self.gates[target_idx].meas_ids.len(); - let gate = self.gates[piece.gate_idx].clone(); - self.gates[target_idx].append_batch(gate); + let qubit_start = self.gate_batches[target_idx].qubits.len(); + let meas_id_start = self.gate_batches[target_idx].meas_ids.len(); + let gate = self.gate_batches[piece.gate_idx].clone(); + self.gate_batches[target_idx].append_batch(gate); self.remove_gate(piece.gate_idx); GateBatchPiece { gate_idx: target_idx, @@ -510,7 +510,7 @@ impl Tick { } fn merge_compatible_gate_at(&mut self, gate_idx: usize) -> usize { - if gate_idx >= self.gates.len() { + if gate_idx >= self.gate_batches.len() { return gate_idx; } self.merge_compatible_piece_at(self.whole_gate_piece(gate_idx)) @@ -518,12 +518,12 @@ impl Tick { } fn isolate_batch_piece(&mut self, piece: GateBatchPiece) -> usize { - if piece.gate_idx >= self.gates.len() { + if piece.gate_idx >= self.gate_batches.len() { return piece.gate_idx; } - let gate_qubit_len = self.gates[piece.gate_idx].qubits.len(); - let gate_meas_id_len = self.gates[piece.gate_idx].meas_ids.len(); + let gate_qubit_len = self.gate_batches[piece.gate_idx].qubits.len(); + let gate_meas_id_len = self.gate_batches[piece.gate_idx].meas_ids.len(); if piece.qubit_start == 0 && piece.qubit_len == gate_qubit_len && piece.meas_id_start == 0 @@ -543,14 +543,15 @@ impl Tick { "batched gate metadata can only split the appended measurement-id suffix" ); - let mut split_gate = self.gates[piece.gate_idx].clone(); - split_gate.qubits = self.gates[piece.gate_idx].qubits[piece.qubit_start..].into(); - split_gate.meas_ids = self.gates[piece.gate_idx].meas_ids[piece.meas_id_start..].into(); + let mut split_gate = self.gate_batches[piece.gate_idx].clone(); + split_gate.qubits = self.gate_batches[piece.gate_idx].qubits[piece.qubit_start..].into(); + split_gate.meas_ids = + self.gate_batches[piece.gate_idx].meas_ids[piece.meas_id_start..].into(); - self.gates[piece.gate_idx] + self.gate_batches[piece.gate_idx] .qubits .truncate(piece.qubit_start); - self.gates[piece.gate_idx] + self.gate_batches[piece.gate_idx] .meas_ids .truncate(piece.meas_id_start); @@ -641,7 +642,7 @@ impl Tick { /// This is computed lazily by iterating through all gates. #[must_use] pub fn active_qubits(&self) -> BTreeSet { - self.gates + self.gate_batches .iter() .flat_map(|gate| gate.qubits.iter().copied()) .collect() @@ -650,7 +651,9 @@ impl Tick { /// Check if a specific qubit is already in use in this tick. #[must_use] pub fn uses_qubit(&self, qubit: QubitId) -> bool { - self.gates.iter().any(|gate| gate.qubits.contains(&qubit)) + self.gate_batches + .iter() + .any(|gate| gate.qubits.contains(&qubit)) } /// Check if any of the given qubits are already in use in this tick. @@ -719,12 +722,12 @@ impl Tick { if let Some(gate_idx) = self.compatible_empty_attr_batch(&gate) { let piece = GateBatchPiece { gate_idx, - qubit_start: self.gates[gate_idx].qubits.len(), + qubit_start: self.gate_batches[gate_idx].qubits.len(), qubit_len: gate.qubits.len(), - meas_id_start: self.gates[gate_idx].meas_ids.len(), + meas_id_start: self.gate_batches[gate_idx].meas_ids.len(), meas_id_len: gate.meas_ids.len(), }; - self.gates[gate_idx].append_batch(gate); + self.gate_batches[gate_idx].append_batch(gate); return Ok(piece); } Ok(self.push_gate_unchecked_piece(gate)) @@ -753,7 +756,7 @@ impl Tick { // Find indices of gates to remove (those using any of the specified qubits) let indices_to_remove: Vec = self - .gates + .gate_batches .iter() .enumerate() .filter(|(_, gate)| gate.qubits.iter().any(|q| qubits_set.contains(q))) @@ -768,7 +771,7 @@ impl Tick { // Remove gates in reverse order to preserve indices for &idx in indices_to_remove.iter().rev() { - self.gates.remove(idx); + self.gate_batches.remove(idx); } // Rebuild gate_attrs with updated indices @@ -803,11 +806,11 @@ impl Tick { /// assert_eq!(tick.len(), 2); // H and Z remain /// ``` pub fn remove_gate(&mut self, idx: usize) -> Option { - if idx >= self.gates.len() { + if idx >= self.gate_batches.len() { return None; } - let gate = self.gates.remove(idx); + let gate = self.gate_batches.remove(idx); // Rebuild gate_attrs with updated indices let old_attrs = std::mem::take(&mut self.gate_attrs); @@ -1422,7 +1425,7 @@ impl TickCircuit { /// operations. Apply either inline channels or a noise model, not both. pub fn try_with_noise(&self, noise: &N) -> Result { for (tick_idx, tick) in self.ticks.iter().enumerate() { - for (gate_idx, gate) in tick.gates().iter().enumerate() { + for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { if gate.is_channel() { return Err(format!( "with_noise cannot apply a noise model to a circuit that already contains channel operations (first channel at tick {tick_idx} gate {gate_idx})" @@ -1441,7 +1444,7 @@ impl TickCircuit { out.ticks.push(tick.clone()); let mut noise_ticks = Vec::new(); - for gate in tick.gates() { + for gate in tick.gate_batches() { for channel in noise.channels_after(gate) { schedule_channel_gate(&mut noise_ticks, Gate::channel(channel)); } @@ -1710,10 +1713,9 @@ impl TickCircuit { /// } /// ``` pub fn iter_gates_with_tick(&self) -> impl Iterator { - self.ticks - .iter() - .enumerate() - .flat_map(|(tick_idx, tick)| tick.gates().iter().map(move |gate| (tick_idx, gate))) + self.ticks.iter().enumerate().flat_map(|(tick_idx, tick)| { + tick.gate_batches().iter().map(move |gate| (tick_idx, gate)) + }) } /// Iterate over full-fidelity gate batches with their tick index. @@ -2006,7 +2008,7 @@ impl TickCircuit { // Try to merge into the latest existing tick where all qubits are free. // Walk backwards to find the latest valid target (ASAP scheduling). for target_idx in (0..compacted.len()).rev() { - let can_merge = tick.gates.iter().all(|gate| { + let can_merge = tick.gate_batches.iter().all(|gate| { gate.qubits .iter() .all(|q| !compacted[target_idx].uses_qubit(*q)) @@ -2016,7 +2018,7 @@ impl TickCircuit { // Check that no tick between target+1..end uses any of these qubits // (would violate ordering). let all_clear = (target_idx + 1..compacted.len()).all(|between| { - tick.gates.iter().all(|gate| { + tick.gate_batches.iter().all(|gate| { gate.qubits .iter() .all(|q| !compacted[between].uses_qubit(*q)) @@ -2025,7 +2027,7 @@ impl TickCircuit { if all_clear { // Move gates and their per-gate metadata into the target tick. - for (gi, gate) in tick.gates.iter().enumerate() { + for (gi, gate) in tick.gate_batches.iter().enumerate() { if let Some(attrs) = tick.gate_attrs.get(&gi) { let new_idx = compacted[target_idx] .try_add_gate_preserving_command(gate.clone()) @@ -2970,7 +2972,7 @@ impl From<&TickCircuit> for DagCircuit { let mut meas_record_idx = 0usize; for (tick_idx, tick) in tc.ticks().iter().enumerate() { - for (gate_idx, gate) in tick.gates().iter().enumerate() { + for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { // Split batched gates into individual operations. // // TickCircuit batches gates for efficiency: @@ -3181,14 +3183,14 @@ mod tests { assert_eq!(tc.gate_count(), 4); assert_eq!(tc.gate_batch_count(), 2); - assert_eq!(tick.gates()[0].gate_type, GateType::H); + assert_eq!(tick.gate_batches()[0].gate_type, GateType::H); assert_eq!( - tick.gates()[0].qubits.as_slice(), + tick.gate_batches()[0].qubits.as_slice(), &[QubitId::from(0), QubitId::from(1)] ); - assert_eq!(tick.gates()[1].gate_type, GateType::CX); + assert_eq!(tick.gate_batches()[1].gate_type, GateType::CX); assert_eq!( - tick.gates()[1].qubits.as_slice(), + tick.gate_batches()[1].qubits.as_slice(), &[ QubitId::from(2), QubitId::from(3), @@ -3247,8 +3249,14 @@ mod tests { assert_eq!(tick.len(), 2); assert_eq!(tick.gate_count(), 2); assert_eq!(tick.gate_batch_count(), 2); - assert_eq!(tick.gates()[0].qubits.as_slice(), &[QubitId::from(0)]); - assert_eq!(tick.gates()[1].qubits.as_slice(), &[QubitId::from(1)]); + assert_eq!( + tick.gate_batches()[0].qubits.as_slice(), + &[QubitId::from(0)] + ); + assert_eq!( + tick.gate_batches()[1].qubits.as_slice(), + &[QubitId::from(1)] + ); assert_eq!(tick.get_gate_attr(0, "calibration"), None); assert_eq!( tick.get_gate_attr(1, "calibration"), @@ -3319,7 +3327,10 @@ mod tests { assert_eq!(refs1[0].gate_idx, 0); assert_eq!(refs0[0].meas_id, MeasId(0)); assert_eq!(refs1[0].meas_id, MeasId(1)); - assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)]); + assert_eq!( + tick.gate_batches()[0].meas_ids.as_slice(), + &[MeasId(0), MeasId(1)] + ); } #[test] @@ -3341,7 +3352,10 @@ mod tests { assert_eq!(tick.len(), 1); assert_eq!(tick.gate_count(), 2); assert_eq!(tick.gate_batch_count(), 1); - assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)]); + assert_eq!( + tick.gate_batches()[0].meas_ids.as_slice(), + &[MeasId(0), MeasId(1)] + ); assert_eq!( tick.get_gate_attr(0, "basis"), Some(&Attribute::String("Z".into())) @@ -3364,8 +3378,8 @@ mod tests { assert_eq!(tick.len(), 2); assert_eq!(tick.gate_count(), 2); assert_eq!(tick.gate_batch_count(), 2); - assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0)]); - assert_eq!(tick.gates()[1].meas_ids.as_slice(), &[MeasId(1)]); + assert_eq!(tick.gate_batches()[0].meas_ids.as_slice(), &[MeasId(0)]); + assert_eq!(tick.gate_batches()[1].meas_ids.as_slice(), &[MeasId(1)]); assert_eq!( tick.get_gate_attr(0, "basis"), Some(&Attribute::String("Z".into())) @@ -3417,16 +3431,19 @@ mod tests { assert_eq!(tick.gate_count(), 3); assert_eq!(tick.gate_batch_count(), 2); assert_eq!( - tick.gates()[0].qubits.as_slice(), + tick.gate_batches()[0].qubits.as_slice(), &[QubitId::from(0), QubitId::from(1)] ); assert_eq!( - tick.gates()[0].angles, + tick.gate_batches()[0].angles, Gate::rz(Angle64::from_turns(0.25), &[0]).angles ); - assert_eq!(tick.gates()[1].qubits.as_slice(), &[QubitId::from(2)]); assert_eq!( - tick.gates()[1].angles, + tick.gate_batches()[1].qubits.as_slice(), + &[QubitId::from(2)] + ); + assert_eq!( + tick.gate_batches()[1].angles, Gate::rz(Angle64::from_turns(0.5), &[2]).angles ); } @@ -3822,10 +3839,13 @@ mod tests { Some(&Attribute::String("b".into())) ); assert_eq!( - tick.gates()[0].qubits.as_slice(), + tick.gate_batches()[0].qubits.as_slice(), &[QubitId::from(0), QubitId::from(2)] ); - assert_eq!(tick.gates()[1].qubits.as_slice(), &[QubitId::from(1)]); + assert_eq!( + tick.gate_batches()[1].qubits.as_slice(), + &[QubitId::from(1)] + ); } #[test] @@ -3857,8 +3877,11 @@ mod tests { assert_eq!(tick.len(), 1); assert_eq!(tick.gate_count(), 2); assert_eq!(tick.gate_batch_count(), 1); - assert_eq!(tick.gates()[0].gate_type, GateType::MZ); - assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)]); + assert_eq!(tick.gate_batches()[0].gate_type, GateType::MZ); + assert_eq!( + tick.gate_batches()[0].meas_ids.as_slice(), + &[MeasId(0), MeasId(1)] + ); assert_eq!( tick.get_gate_attr(0, "basis"), Some(&Attribute::String("Z".into())) @@ -3879,7 +3902,7 @@ mod tests { assert_eq!(tc1.gate_count(), 1); assert_eq!(tc1.gate_batch_count(), 1); assert_eq!( - tick.gates()[0].qubits.as_slice(), + tick.gate_batches()[0].qubits.as_slice(), &[QubitId::from(0), QubitId::from(1)] ); @@ -3930,7 +3953,10 @@ mod tests { } let tick = tc2.get_tick(0).unwrap(); - assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)]); + assert_eq!( + tick.gate_batches()[0].meas_ids.as_slice(), + &[MeasId(0), MeasId(1)] + ); } #[test] @@ -3951,8 +3977,11 @@ mod tests { let tick = tc.get_tick(0).unwrap(); assert_eq!(tick.len(), 1); - assert_eq!(tick.gates()[0].gate_type, GateType::MZ); - assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)]); + assert_eq!(tick.gate_batches()[0].gate_type, GateType::MZ); + assert_eq!( + tick.gate_batches()[0].meas_ids.as_slice(), + &[MeasId(0), MeasId(1)] + ); } #[test] @@ -3966,7 +3995,7 @@ mod tests { let mut tc = TickCircuit::from(&dag); assert_eq!(tc.num_measurements(), 6); let tick = tc.get_tick(0).unwrap(); - assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(5)]); + assert_eq!(tick.gate_batches()[0].meas_ids.as_slice(), &[MeasId(5)]); match &tc.annotations()[0].kind { AnnotationKind::Observable { measurement_nodes } => { assert_eq!(measurement_nodes.as_slice(), &[5]); @@ -4033,7 +4062,7 @@ mod tests { fn assert_no_tick_overlaps(circuit: &TickCircuit) { for (tick_idx, tick) in circuit.ticks().iter().enumerate() { let mut active = BTreeSet::new(); - for gate in tick.gates() { + for gate in tick.gate_batches() { gate.validate() .unwrap_or_else(|err| panic!("invalid gate in tick {tick_idx}: {err}")); for &qubit in &gate.qubits { @@ -4529,11 +4558,11 @@ mod tests { assert_eq!(tick.gate_count(), 5); assert_eq!(tick.gate_batch_count(), 4); assert_eq!( - tick.gates()[0].qubits.as_slice(), + tick.gate_batches()[0].qubits.as_slice(), &[QubitId::from(0), QubitId::from(1)] ); - assert!(tick.gates()[2].is_channel()); - assert!(tick.gates()[3].is_channel()); + assert!(tick.gate_batches()[2].is_channel()); + assert!(tick.gate_batches()[3].is_channel()); let mut meas = TickCircuit::new(); meas.reserve_ticks(1); @@ -4556,8 +4585,11 @@ mod tests { assert_eq!(tick.len(), 2); assert_eq!(tick.gate_count(), 3); assert_eq!(tick.gate_batch_count(), 2); - assert_eq!(tick.gates()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)]); - assert_eq!(tick.gates()[1].meas_ids.as_slice(), &[MeasId(2)]); + assert_eq!( + tick.gate_batches()[0].meas_ids.as_slice(), + &[MeasId(0), MeasId(1)] + ); + assert_eq!(tick.gate_batches()[1].meas_ids.as_slice(), &[MeasId(2)]); } #[test] @@ -5151,7 +5183,7 @@ mod tests { assert_eq!(removed, 2); // H on q0 and CX on q2,q3 assert_eq!(tick.len(), 1); // Only X on q1 remains - assert_eq!(tick.gates()[0].gate_type, GateType::X); + assert_eq!(tick.gate_batches()[0].gate_type, GateType::X); } #[test] @@ -5206,8 +5238,8 @@ mod tests { assert_eq!(tick.len(), 2); // Check remaining gates - assert_eq!(tick.gates()[0].gate_type, GateType::H); - assert_eq!(tick.gates()[1].gate_type, GateType::Z); + assert_eq!(tick.gate_batches()[0].gate_type, GateType::H); + assert_eq!(tick.gate_batches()[1].gate_type, GateType::Z); } #[test] @@ -5321,7 +5353,7 @@ mod tests { .expect("should succeed"); let tick = tc.get_tick(0).unwrap(); - let gate = &tick.gates()[0]; + let gate = &tick.gate_batches()[0]; assert_eq!(gate.gate_type, GateType::Custom); assert_eq!(gate.angles.len(), 2); assert_eq!(gate.angles[0], a1); @@ -5588,9 +5620,15 @@ mod tests { let noise_tick = noisy.get_tick(1).unwrap(); assert_eq!(noise_tick.len(), 2); assert_eq!(noise_tick.gate_count(), 2); - assert!(noise_tick.gates().iter().all(Gate::is_channel)); - assert_eq!(noise_tick.gates()[0].qubits.as_slice(), &[QubitId::from(0)]); - assert_eq!(noise_tick.gates()[1].qubits.as_slice(), &[QubitId::from(1)]); + assert!(noise_tick.gate_batches().iter().all(Gate::is_channel)); + assert_eq!( + noise_tick.gate_batches()[0].qubits.as_slice(), + &[QubitId::from(0)] + ); + assert_eq!( + noise_tick.gate_batches()[1].qubits.as_slice(), + &[QubitId::from(1)] + ); } #[test] @@ -5622,17 +5660,23 @@ mod tests { assert_eq!(noisy.num_ticks(), 2); let meas_tick = noisy.get_tick(0).unwrap(); - assert_eq!(meas_tick.gates()[0].gate_type, GateType::MZ); + assert_eq!(meas_tick.gate_batches()[0].gate_type, GateType::MZ); assert_eq!( - meas_tick.gates()[0].meas_ids.as_slice(), + meas_tick.gate_batches()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)] ); let noise_tick = noisy.get_tick(1).unwrap(); assert_eq!(noise_tick.len(), 2); - assert!(noise_tick.gates().iter().all(Gate::is_channel)); - assert_eq!(noise_tick.gates()[0].qubits.as_slice(), &[QubitId::from(0)]); - assert_eq!(noise_tick.gates()[1].qubits.as_slice(), &[QubitId::from(1)]); + assert!(noise_tick.gate_batches().iter().all(Gate::is_channel)); + assert_eq!( + noise_tick.gate_batches()[0].qubits.as_slice(), + &[QubitId::from(0)] + ); + assert_eq!( + noise_tick.gate_batches()[1].qubits.as_slice(), + &[QubitId::from(1)] + ); } #[test] @@ -5673,18 +5717,18 @@ mod tests { assert_eq!(noisy.get_tick(0).unwrap().gates()[0].gate_type, GateType::H); let first_noise_tick = noisy.get_tick(1).unwrap(); - assert_eq!(first_noise_tick.gates().len(), 1); - assert!(first_noise_tick.gates()[0].is_channel()); + assert_eq!(first_noise_tick.gate_batches().len(), 1); + assert!(first_noise_tick.gate_batches()[0].is_channel()); assert_eq!( - first_noise_tick.gates()[0].qubits.as_slice(), + first_noise_tick.gate_batches()[0].qubits.as_slice(), &[QubitId::from(0)] ); let second_noise_tick = noisy.get_tick(2).unwrap(); - assert_eq!(second_noise_tick.gates().len(), 1); - assert!(second_noise_tick.gates()[0].is_channel()); + assert_eq!(second_noise_tick.gate_batches().len(), 1); + assert!(second_noise_tick.gate_batches()[0].is_channel()); assert_eq!( - second_noise_tick.gates()[0].qubits.as_slice(), + second_noise_tick.gate_batches()[0].qubits.as_slice(), &[QubitId::from(0)] ); } From 5afd5d37ee240683931bbe7a2c5521dd27ca4f29 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 11:48:49 -0600 Subject: [PATCH 105/125] Use explicit batched gate access internally --- .../benches/modules/tick_circuit_layout.rs | 4 ++-- .../src/fault_tolerance/circuit_runner.rs | 8 ++++---- .../src/fault_tolerance/fault_sampler.rs | 8 ++++---- .../src/fault_tolerance/gadget_checker.rs | 4 ++-- .../src/fault_tolerance/pauli_prop_checker.rs | 18 +++++++++--------- .../src/fault_tolerance/propagator/pauli.rs | 8 ++++---- .../src/fault_tolerance/propagator/tick.rs | 8 ++++---- crates/pecos-quantum/src/tick_circuit.rs | 18 +++++++++++++----- 8 files changed, 42 insertions(+), 34 deletions(-) diff --git a/crates/benchmarks/benches/modules/tick_circuit_layout.rs b/crates/benchmarks/benches/modules/tick_circuit_layout.rs index c7e05f848..1550bfb71 100644 --- a/crates/benchmarks/benches/modules/tick_circuit_layout.rs +++ b/crates/benchmarks/benches/modules/tick_circuit_layout.rs @@ -253,7 +253,7 @@ fn traverse_tick_circuit(circuit: &TickCircuit) -> usize { let mut total = 0usize; for (tick_idx, tick) in circuit.iter_ticks() { total = total.wrapping_add(tick_idx); - for gate in tick.gates() { + for gate in tick.gate_batches() { total = total.wrapping_add(gate.num_gates()); total = total.wrapping_add(gate.qubits.len()); } @@ -276,7 +276,7 @@ fn run_tick_circuit_direct(circuit: &TickCircuit, num_qubits: usize) -> usize { let mut measurement_count = 0usize; for (_tick_idx, tick) in circuit.iter_ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { measurement_count += execute_gate_direct(&mut sim, gate); } } diff --git a/crates/pecos-qec/src/fault_tolerance/circuit_runner.rs b/crates/pecos-qec/src/fault_tolerance/circuit_runner.rs index 71e154b2f..78491196a 100644 --- a/crates/pecos-qec/src/fault_tolerance/circuit_runner.rs +++ b/crates/pecos-qec/src/fault_tolerance/circuit_runner.rs @@ -60,7 +60,7 @@ pub fn extract_spacetime_locations( // Iterate through all ticks for (tick_idx, tick) in circuit.iter_ticks() { - for (gate_idx, gate) in tick.gates().iter().enumerate() { + for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { let qubits: Vec = gate.qubits.iter().copied().collect(); let is_measurement = matches!(gate.gate_type, GateType::MZ | GateType::MeasureFree); @@ -105,9 +105,9 @@ fn apply_fault(sim: &mut S, fault: &PauliFault) { /// simulator-level batch optimizations (gate fusion, SIMD batching, etc.). fn apply_tick_gates(sim: &mut S, tick: &pecos_quantum::Tick) { // For ticks with few gates, skip consolidation overhead - let gate_count = tick.gates().len(); + let gate_count = tick.gate_batches().len(); if gate_count <= 2 { - for gate in tick.gates() { + for gate in tick.gate_batches() { apply_gate(sim, gate); } return; @@ -139,7 +139,7 @@ fn apply_tick_gates(sim: &mut S, tick: &pecos_quantum::Tick let mut mz_qubits: Vec = Vec::new(); let mut pz_qubits: Vec = Vec::new(); - for gate in tick.gates() { + for gate in tick.gate_batches() { match gate.gate_type { GateType::H => h_qubits.extend(gate.qubits.iter()), GateType::X => x_qubits.extend(gate.qubits.iter()), diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index 6782754b4..a7a3e9167 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -231,7 +231,7 @@ pub fn build_fault_table( /// Validate that all gates in the `TickCircuit` are supported (before flattening). fn validate_tick_circuit(tc: &TickCircuit) -> Result<(), UnsupportedGateError> { for (tick_idx, tick) in tc.ticks().iter().enumerate() { - for (gate_idx, gate) in tick.gates().iter().enumerate() { + for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { if is_standard_1q_clifford_gate(gate.gate_type) || is_standard_2q_clifford_gate(gate.gate_type) || is_supported_measurement_gate(gate.gate_type) @@ -262,7 +262,7 @@ pub(crate) fn flatten_tick_circuit(tc: &TickCircuit) -> (Vec, HashMap = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); let is_mz = is_supported_measurement_gate(gate.gate_type); let is_2q = is_standard_2q_clifford_gate(gate.gate_type); @@ -1514,7 +1514,7 @@ pub fn symbolic_measurement_history( let num_qubits = tc .ticks() .iter() - .flat_map(|t| t.gates().iter()) + .flat_map(|t| t.gate_batches().iter()) .flat_map(|g| g.qubits.iter()) .map(|q| q.index() + 1) .max() @@ -1523,7 +1523,7 @@ pub fn symbolic_measurement_history( let mut sim = SymbolicSparseStab::new(num_qubits); for (tick_idx, tick) in tc.ticks().iter().enumerate() { - for (gate_idx, gate) in tick.gates().iter().enumerate() { + for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { let qs: Vec = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); match gate.gate_type { diff --git a/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs b/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs index 6fff939f4..c9ea58d21 100644 --- a/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs +++ b/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs @@ -963,7 +963,7 @@ impl<'a> GadgetChecker<'a> { /// Propagate a `PauliProp` through the circuit without additional faults. fn propagate_through_circuit(&self, mut prop: PauliProp) -> PauliProp { for tick in self.circuit.ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { let qubits: Vec = gate.qubits.to_vec(); match gate.gate_type { @@ -1741,7 +1741,7 @@ impl<'a> GadgetChecker<'a> { } // Apply gates - for gate in tick.gates() { + for gate in tick.gate_batches() { let qubits: Vec = gate.qubits.to_vec(); match gate.gate_type { pecos_core::gate_type::GateType::H => { diff --git a/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs b/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs index 634fe6a1e..c1042d02b 100644 --- a/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs +++ b/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs @@ -76,7 +76,7 @@ pub fn detect_input_qubits(circuit: &TickCircuit) -> Vec { let mut prepared_qubits: HashSet = HashSet::new(); for (_tick_idx, tick) in circuit.iter_ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { for &qubit in &gate.qubits { let q = qubit.index(); all_qubits.insert(q); @@ -108,7 +108,7 @@ pub fn detect_ancilla_qubits(circuit: &TickCircuit) -> Vec { let mut prepared_qubits: HashSet = HashSet::new(); for (_tick_idx, tick) in circuit.iter_ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { if gate.gate_type == GateType::PZ { for &qubit in &gate.qubits { prepared_qubits.insert(qubit.index()); @@ -142,7 +142,7 @@ pub fn detect_output_qubits(circuit: &TickCircuit) -> Vec { let mut measured_qubits: HashSet = HashSet::new(); for (_tick_idx, tick) in circuit.iter_ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { for &qubit in &gate.qubits { let q = qubit.index(); all_qubits.insert(q); @@ -191,7 +191,7 @@ impl CircuitIO { let mut measured_qubits: HashSet = HashSet::new(); for (_tick_idx, tick) in circuit.iter_ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { for &qubit in &gate.qubits { let q = qubit.index(); all_qubits.insert(q); @@ -296,7 +296,7 @@ pub fn propagate_fault(circuit: &TickCircuit, fault: &PauliFault) -> PauliProp { } // Apply all gates in this tick - for gate in tick.gates() { + for gate in tick.gate_batches() { apply_gate(&mut prop, gate, Direction::Forward); } } @@ -335,7 +335,7 @@ pub fn propagate_faults(circuit: &TickCircuit, faults: &FaultConfiguration) -> P // Propagate through the circuit from the minimum tick onward for (tick_idx, tick) in circuit.iter_ticks() { if tick_idx >= min_tick { - for gate in tick.gates() { + for gate in tick.gate_batches() { apply_gate(&mut prop, gate, Direction::Forward); } } @@ -1011,7 +1011,7 @@ pub fn extract_measurement_rounds(circuit: &TickCircuit) -> Vec { // Z-basis measurement @@ -1070,7 +1070,7 @@ fn propagate_until_tick(circuit: &TickCircuit, fault: &PauliFault, until_tick: u } // Propagate through all gates in this tick - for gate in tick.gates() { + for gate in tick.gate_batches() { let qubits: Vec = gate.qubits.iter().copied().collect(); match gate.gate_type { GateType::CX if qubits.len() >= 2 => { @@ -2124,7 +2124,7 @@ impl<'a> PauliPropChecker<'a> { // Propagate through circuit for (_tick_idx, tick) in self.circuit.iter_ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { apply_gate(&mut prop, gate, Direction::Forward); } } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/pauli.rs b/crates/pecos-qec/src/fault_tolerance/propagator/pauli.rs index eabeff99e..b1aecd0a6 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/pauli.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/pauli.rs @@ -264,14 +264,14 @@ pub fn propagate_through_circuit( match direction { Direction::Forward => { for tick in circuit.ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { apply_gate(prop, gate, direction); } } } Direction::Backward => { for tick in circuit.ticks().iter().rev() { - for gate in tick.gates() { + for gate in tick.gate_batches() { apply_gate(prop, gate, direction); } } @@ -305,7 +305,7 @@ pub fn propagate_tick_range( Direction::Forward => { for tick_idx in start..=end { let tick = &circuit.ticks()[tick_idx]; - for gate in tick.gates() { + for gate in tick.gate_batches() { apply_gate(prop, gate, direction); } } @@ -313,7 +313,7 @@ pub fn propagate_tick_range( Direction::Backward => { for tick_idx in (start..=end).rev() { let tick = &circuit.ticks()[tick_idx]; - for gate in tick.gates() { + for gate in tick.gate_batches() { apply_gate(prop, gate, direction); } } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs b/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs index 6bd895238..42d5d3b68 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs @@ -64,7 +64,7 @@ impl<'a> TickFaultAnalyzer<'a> { // Find max qubit for active qubit tracking let mut max_qubit = 0; for tick in circuit.ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { for qubit in &gate.qubits { max_qubit = max_qubit.max(qubit.index()); } @@ -151,7 +151,7 @@ impl<'a> TickFaultAnalyzer<'a> { let mut measurements = Vec::new(); for (tick_idx, tick) in self.circuit.iter_ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { // Currently only Z-basis measurements are supported let basis = match gate.gate_type { GateType::MZ | GateType::MeasureFree => 0, // Z-basis @@ -229,7 +229,7 @@ impl<'a> TickFaultAnalyzer<'a> { // Apply gates at this tick backward - SPARSE: only gates touching active qubits if tick_idx < self.circuit.ticks().len() { let tick = &self.circuit.ticks()[tick_idx]; - for gate in tick.gates() { + for gate in tick.gate_batches() { // Check if this gate touches any active qubit let touches_active = gate.qubits.iter().any(|q| { let idx = q.index(); @@ -319,7 +319,7 @@ impl<'a> TickFaultAnalyzer<'a> { // Apply gates backward - SPARSE: only gates touching active qubits let tick = &self.circuit.ticks()[tick_idx]; - for gate in tick.gates() { + for gate in tick.gate_batches() { // Check if this gate touches any active qubit let touches_active = gate.qubits.iter().any(|q| { let idx = q.index(); diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index 6deed9cbf..7d74de549 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -393,7 +393,11 @@ impl Tick { self.gate_batches.is_empty() } - /// Get the gates in this tick. + /// Get the stored gate commands in this tick. + /// + /// A stored command may be a batch containing multiple gate applications on + /// disjoint qubits. Prefer [`gate_batches`](Self::gate_batches) in + /// execution/analyzer code where that distinction matters. #[must_use] pub fn gates(&self) -> &[Gate] { &self.gate_batches @@ -414,7 +418,7 @@ impl Tick { &self.gate_batches } - /// Get mutable access to the gates in this tick. + /// Get mutable access to the stored gate commands in this tick. pub fn gates_mut(&mut self) -> &mut [Gate] { &mut self.gate_batches } @@ -1192,7 +1196,7 @@ impl TickCircuit { let layers: Vec> = self .ticks .iter() - .map(|t| t.gates().iter().collect()) + .map(|t| t.gate_batches().iter().collect()) .collect(); let num_qubits = self.all_qubits().len(); let header = format!( @@ -1659,9 +1663,13 @@ impl TickCircuit { // --- Iteration helpers --- - /// Iterate over all gates in the circuit, across all ticks. + /// Iterate over all stored gate commands in the circuit, across all ticks. + /// + /// A yielded command may be a batch containing multiple gate applications + /// on disjoint qubits. Prefer [`iter_gate_batches`](Self::iter_gate_batches) + /// in execution/analyzer code where that distinction matters. /// - /// Gates are yielded in tick order, then in order within each tick. + /// Commands are yielded in tick order, then in order within each tick. /// /// # Examples /// From b454109d31572966d084672ca3038ebc8d903e75 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 11:56:38 -0600 Subject: [PATCH 106/125] Use batched gate terminology in Rust internals --- crates/pecos-quantum/src/pass.rs | 140 +++++++++--------- crates/pecos-quantum/src/tick_circuit.rs | 9 +- exp/pecos-eeg/src/builder.rs | 6 +- exp/pecos-eeg/tests/surface_code.rs | 4 +- exp/pecos-neo/src/circuit.rs | 6 +- exp/pecos-neo/src/engines.rs | 2 +- exp/pecos-neo/src/inline_channel.rs | 4 +- exp/pecos-zx/src/viz/circuit_layout.rs | 2 +- .../pecos-rslib/src/dag_circuit_bindings.rs | 10 +- 9 files changed, 92 insertions(+), 91 deletions(-) diff --git a/crates/pecos-quantum/src/pass.rs b/crates/pecos-quantum/src/pass.rs index c39f6f39f..b19f57d81 100644 --- a/crates/pecos-quantum/src/pass.rs +++ b/crates/pecos-quantum/src/pass.rs @@ -235,7 +235,7 @@ impl CircuitPass for InsertIdleAfterTwoQubitGates { for tick in old_ticks { let mut idle_qubits: Vec = Vec::new(); - for gate in tick.gates() { + for gate in tick.gate_batches() { if gate.is_two_qubit() { for q in &gate.qubits { if !idle_qubits.contains(q) { @@ -452,7 +452,7 @@ fn split_batched_tick_commands(circuit: &mut TickCircuit) { new_tick.set_attr(key, value.clone()); } - for (gate_idx, gate) in old_tick.gates().iter().enumerate() { + for (gate_idx, gate) in old_tick.gate_batches().iter().enumerate() { let attrs: BTreeMap = old_tick .gate_attrs(gate_idx) .map(|(key, value)| (key.clone(), value.clone())) @@ -509,7 +509,7 @@ impl CircuitPass for SimplifyRotations { // We need to know which gate indices to remove and what to add. let mut decompositions: Vec<(usize, GateType)> = Vec::new(); - for (i, gate) in tick.gates().iter().enumerate() { + for (i, gate) in tick.gate_batches().iter().enumerate() { if gate.angles.len() == 1 && let Some(pauli) = pecos_core::half_turn_decomposition(gate.gate_type, gate.angles[0]) @@ -520,7 +520,7 @@ impl CircuitPass for SimplifyRotations { // Process decompositions in reverse order to keep indices valid. for &(idx, pauli) in decompositions.iter().rev() { - let qubits = tick.gates()[idx].qubits.clone(); + let qubits = tick.gate_batches()[idx].qubits.clone(); // Remove the two-qubit gate, add two single-qubit gates. tick.remove_gate(idx); for pair in qubits.chunks(2) { @@ -615,7 +615,7 @@ impl CircuitPass for RemoveIdentity { fn apply_tick(&self, circuit: &mut TickCircuit) { for tick in circuit.ticks_mut() { let to_remove: Vec = tick - .gates() + .gate_batches() .iter() .enumerate() .filter(|(_, g)| is_identity_gate(g)) @@ -665,11 +665,11 @@ impl CircuitPass for CancelInverses { let mut to_remove: Vec<(usize, usize)> = Vec::new(); for (ti, tick) in circuit.ticks().iter().enumerate() { - for (gi, gate) in tick.gates().iter().enumerate() { + for (gi, gate) in tick.gate_batches().iter().enumerate() { let qubits: Vec = gate.qubits.iter().copied().collect(); if let Some((pred_ti, pred_gi)) = check_all_stacks_agree(&stacks, &qubits) { - let pred_gate = &circuit.ticks()[pred_ti].gates()[pred_gi]; + let pred_gate = &circuit.ticks()[pred_ti].gate_batches()[pred_gi]; if are_inverses(pred_gate, gate) { for &q in &qubits { if let Some(stack) = stacks.get_mut(&q) { @@ -748,14 +748,14 @@ impl CircuitPass for MergeAdjacentRotations { let mut to_remove: Vec<(usize, usize)> = Vec::new(); for (ti, tick) in circuit.ticks().iter().enumerate() { - for (gi, gate) in tick.gates().iter().enumerate() { + for (gi, gate) in tick.gate_batches().iter().enumerate() { let qubits: Vec = gate.qubits.iter().copied().collect(); if is_rotation(gate.gate_type) && gate.angles.len() == 1 && let Some((pred_ti, pred_gi)) = check_all_stacks_agree(&stacks, &qubits) { - let pred_gate = &circuit.ticks()[pred_ti].gates()[pred_gi]; + let pred_gate = &circuit.ticks()[pred_ti].gate_batches()[pred_gi]; if pred_gate.gate_type == gate.gate_type && pred_gate.qubits == gate.qubits { *angle_adjustments .entry((pred_ti, pred_gi)) @@ -855,7 +855,7 @@ impl CircuitPass for PeepholeOptimize { // Build per-qubit timeline: Vec of (tick_idx, gate_idx) in order. let mut timelines: HashMap> = HashMap::new(); for (ti, tick) in circuit.ticks().iter().enumerate() { - for (gi, gate) in tick.gates().iter().enumerate() { + for (gi, gate) in tick.gate_batches().iter().enumerate() { for &q in &gate.qubits { timelines.entry(q).or_default().push((ti, gi)); } @@ -885,9 +885,9 @@ impl CircuitPass for PeepholeOptimize { continue; } - let h1 = &circuit.ticks()[h1_ti].gates()[h1_gi]; - let mid = &circuit.ticks()[mid_ti].gates()[mid_gi]; - let h2 = &circuit.ticks()[h2_ti].gates()[h2_gi]; + let h1 = &circuit.ticks()[h1_ti].gate_batches()[h1_gi]; + let mid = &circuit.ticks()[mid_ti].gate_batches()[mid_gi]; + let h2 = &circuit.ticks()[h2_ti].gate_batches()[h2_gi]; // Both must be single-qubit H on this qubit. if h1.gate_type != GateType::H @@ -1049,7 +1049,7 @@ impl CircuitPass for AbsorbBasisGates { // Forward scan: absorb Z-diagonal gates after Z-preps. let mut z_eigenstate: HashSet = HashSet::new(); for (ti, tick) in circuit.ticks().iter().enumerate() { - for (gi, gate) in tick.gates().iter().enumerate() { + for (gi, gate) in tick.gate_batches().iter().enumerate() { if is_z_prep(gate.gate_type) { for &q in &gate.qubits { z_eigenstate.insert(q); @@ -1069,7 +1069,7 @@ impl CircuitPass for AbsorbBasisGates { // Backward scan: absorb Z-diagonal gates before Z-measures. let mut before_z_measure: HashSet = HashSet::new(); for (ti, tick) in circuit.ticks().iter().enumerate().rev() { - for (gi, gate) in tick.gates().iter().enumerate().rev() { + for (gi, gate) in tick.gate_batches().iter().enumerate().rev() { if is_z_measure(gate.gate_type) { for &q in &gate.qubits { before_z_measure.insert(q); @@ -1179,7 +1179,7 @@ impl CircuitPass for CompactTicks { // Collect every gate together with its per-gate attributes. let mut entries: Vec<(Gate, BTreeMap)> = Vec::new(); for tick in circuit.ticks() { - for (gi, gate) in tick.gates().iter().enumerate() { + for (gi, gate) in tick.gate_batches().iter().enumerate() { let attrs: BTreeMap = tick .gate_attrs(gi) .map(|(k, v)| (k.clone(), v.clone())) @@ -1451,7 +1451,7 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().rz(Angle64::QUARTER_TURN, &[0]); SimplifyRotations.apply_tick(&mut tc); - let gate = &tc.ticks()[0].gates()[0]; + let gate = &tc.ticks()[0].gate_batches()[0]; assert_eq!(gate.gate_type, GateType::SZ); assert!(gate.angles.is_empty()); } @@ -1461,7 +1461,7 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().rz(Angle64::HALF_TURN, &[0]); SimplifyRotations.apply_tick(&mut tc); - let gate = &tc.ticks()[0].gates()[0]; + let gate = &tc.ticks()[0].gate_batches()[0]; assert_eq!(gate.gate_type, GateType::Z); assert!(gate.angles.is_empty()); } @@ -1471,7 +1471,7 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().rx(Angle64::QUARTER_TURN, &[0]); SimplifyRotations.apply_tick(&mut tc); - let gate = &tc.ticks()[0].gates()[0]; + let gate = &tc.ticks()[0].gate_batches()[0]; assert_eq!(gate.gate_type, GateType::SX); assert!(gate.angles.is_empty()); } @@ -1481,7 +1481,7 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().ry(Angle64::HALF_TURN, &[0]); SimplifyRotations.apply_tick(&mut tc); - let gate = &tc.ticks()[0].gates()[0]; + let gate = &tc.ticks()[0].gate_batches()[0]; assert_eq!(gate.gate_type, GateType::Y); assert!(gate.angles.is_empty()); } @@ -1491,7 +1491,7 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().rzz(Angle64::QUARTER_TURN, &[(0, 1)]); SimplifyRotations.apply_tick(&mut tc); - let gate = &tc.ticks()[0].gates()[0]; + let gate = &tc.ticks()[0].gate_batches()[0]; assert_eq!(gate.gate_type, GateType::SZZ); assert!(gate.angles.is_empty()); } @@ -1501,7 +1501,7 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().rzz(Angle64::HALF_TURN, &[(0, 1)]); SimplifyRotations.apply_tick(&mut tc); - let gates = tc.ticks()[0].gates(); + let gates = tc.ticks()[0].gate_batches(); assert_eq!(gates.len(), 1); assert_eq!(gates[0].gate_type, GateType::Z); assert_eq!( @@ -1516,7 +1516,7 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().rxx(Angle64::HALF_TURN, &[(0, 1)]); SimplifyRotations.apply_tick(&mut tc); - let gates = tc.ticks()[0].gates(); + let gates = tc.ticks()[0].gate_batches(); assert_eq!(gates.len(), 1); assert_eq!(gates[0].gate_type, GateType::X); assert_eq!( @@ -1531,7 +1531,7 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().rz(Angle64::from_turn_ratio(1, 6), &[0]); SimplifyRotations.apply_tick(&mut tc); - let gate = &tc.ticks()[0].gates()[0]; + let gate = &tc.ticks()[0].gate_batches()[0]; assert_eq!(gate.gate_type, GateType::RZ); assert_eq!(gate.angles.len(), 1); } @@ -1541,7 +1541,7 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().h(&[0]); SimplifyRotations.apply_tick(&mut tc); - let gate = &tc.ticks()[0].gates()[0]; + let gate = &tc.ticks()[0].gate_batches()[0]; assert_eq!(gate.gate_type, GateType::H); } @@ -1550,7 +1550,7 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().rz(Angle64::from_turn_ratio(1, 8), &[0]); SimplifyRotations.apply_tick(&mut tc); - let gate = &tc.ticks()[0].gates()[0]; + let gate = &tc.ticks()[0].gate_batches()[0]; assert_eq!(gate.gate_type, GateType::T); assert!(gate.angles.is_empty()); } @@ -1765,7 +1765,7 @@ mod tests { let mut tick_ops: Vec = Vec::new(); for tick in tc.ticks() { - let gates = tick.gates(); + let gates = tick.gate_batches(); if gates.is_empty() { continue; } @@ -2159,7 +2159,7 @@ mod tests { tc.tick(); tc.ticks_mut()[0].add_gate(Gate::i(&[0])); RemoveIdentity.apply_tick(&mut tc); - assert!(tc.ticks()[0].gates().is_empty()); + assert!(tc.ticks()[0].gate_batches().is_empty()); } #[test] @@ -2167,7 +2167,7 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().rz(Angle64::ZERO, &[0]); RemoveIdentity.apply_tick(&mut tc); - assert!(tc.ticks()[0].gates().is_empty()); + assert!(tc.ticks()[0].gate_batches().is_empty()); } #[test] @@ -2175,8 +2175,8 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().rz(Angle64::QUARTER_TURN, &[0]); RemoveIdentity.apply_tick(&mut tc); - assert_eq!(tc.ticks()[0].gates().len(), 1); - assert_eq!(tc.ticks()[0].gates()[0].gate_type, GateType::RZ); + assert_eq!(tc.ticks()[0].gate_batches().len(), 1); + assert_eq!(tc.ticks()[0].gate_batches()[0].gate_type, GateType::RZ); } #[test] @@ -2185,8 +2185,8 @@ mod tests { tc.tick().h(&[0]); tc.ticks_mut()[0].add_gate(Gate::i(&[1])); RemoveIdentity.apply_tick(&mut tc); - assert_eq!(tc.ticks()[0].gates().len(), 1); - assert_eq!(tc.ticks()[0].gates()[0].gate_type, GateType::H); + assert_eq!(tc.ticks()[0].gate_batches().len(), 1); + assert_eq!(tc.ticks()[0].gate_batches()[0].gate_type, GateType::H); } // ==================== RemoveIdentity DAG tests ==================== @@ -2235,8 +2235,8 @@ mod tests { tc.tick().h(&[0]); tc.tick().h(&[0]); CancelInverses.apply_tick(&mut tc); - assert!(tc.ticks()[0].gates().is_empty()); - assert!(tc.ticks()[1].gates().is_empty()); + assert!(tc.ticks()[0].gate_batches().is_empty()); + assert!(tc.ticks()[1].gate_batches().is_empty()); } #[test] @@ -2245,8 +2245,8 @@ mod tests { tc.tick().x(&[0]); tc.tick().x(&[0]); CancelInverses.apply_tick(&mut tc); - assert!(tc.ticks()[0].gates().is_empty()); - assert!(tc.ticks()[1].gates().is_empty()); + assert!(tc.ticks()[0].gate_batches().is_empty()); + assert!(tc.ticks()[1].gate_batches().is_empty()); } #[test] @@ -2256,8 +2256,8 @@ mod tests { tc.tick(); tc.ticks_mut()[1].add_gate(Gate::sxdg(&[0])); CancelInverses.apply_tick(&mut tc); - assert!(tc.ticks()[0].gates().is_empty()); - assert!(tc.ticks()[1].gates().is_empty()); + assert!(tc.ticks()[0].gate_batches().is_empty()); + assert!(tc.ticks()[1].gate_batches().is_empty()); } #[test] @@ -2267,8 +2267,8 @@ mod tests { tc.tick(); tc.ticks_mut()[1].add_gate(Gate::tdg(&[0])); CancelInverses.apply_tick(&mut tc); - assert!(tc.ticks()[0].gates().is_empty()); - assert!(tc.ticks()[1].gates().is_empty()); + assert!(tc.ticks()[0].gate_batches().is_empty()); + assert!(tc.ticks()[1].gate_batches().is_empty()); } #[test] @@ -2277,8 +2277,8 @@ mod tests { tc.tick().cx(&[(0, 1)]); tc.tick().cx(&[(0, 1)]); CancelInverses.apply_tick(&mut tc); - assert!(tc.ticks()[0].gates().is_empty()); - assert!(tc.ticks()[1].gates().is_empty()); + assert!(tc.ticks()[0].gate_batches().is_empty()); + assert!(tc.ticks()[1].gate_batches().is_empty()); } #[test] @@ -2288,8 +2288,8 @@ mod tests { tc.tick().rz(angle, &[0]); tc.tick().rz(-angle, &[0]); CancelInverses.apply_tick(&mut tc); - assert!(tc.ticks()[0].gates().is_empty()); - assert!(tc.ticks()[1].gates().is_empty()); + assert!(tc.ticks()[0].gate_batches().is_empty()); + assert!(tc.ticks()[1].gate_batches().is_empty()); } #[test] @@ -2303,7 +2303,7 @@ mod tests { tc.tick().h(&[0]); CancelInverses.apply_tick(&mut tc); for tick in tc.ticks() { - assert!(tick.gates().is_empty()); + assert!(tick.gate_batches().is_empty()); } } @@ -2315,9 +2315,9 @@ mod tests { tc.tick().x(&[0]); tc.tick().h(&[0]); CancelInverses.apply_tick(&mut tc); - assert_eq!(tc.ticks()[0].gates().len(), 1); - assert_eq!(tc.ticks()[1].gates().len(), 1); - assert_eq!(tc.ticks()[2].gates().len(), 1); + assert_eq!(tc.ticks()[0].gate_batches().len(), 1); + assert_eq!(tc.ticks()[1].gate_batches().len(), 1); + assert_eq!(tc.ticks()[2].gate_batches().len(), 1); } #[test] @@ -2326,8 +2326,8 @@ mod tests { tc.tick().h(&[0]); tc.tick().h(&[1]); CancelInverses.apply_tick(&mut tc); - assert_eq!(tc.ticks()[0].gates().len(), 1); - assert_eq!(tc.ticks()[1].gates().len(), 1); + assert_eq!(tc.ticks()[0].gate_batches().len(), 1); + assert_eq!(tc.ticks()[1].gate_batches().len(), 1); } // ==================== CancelInverses DAG tests ==================== @@ -2567,20 +2567,20 @@ mod tests { // ==================== Pass effectiveness analysis ==================== - /// Count total gates across all ticks. - fn count_gates(tc: &TickCircuit) -> usize { - tc.ticks().iter().map(|t| t.gates().len()).sum() + /// Count stored gate batches across all ticks. + fn count_gate_batches(tc: &TickCircuit) -> usize { + tc.ticks().iter().map(|t| t.gate_batches().len()).sum() } - /// Apply the full pipeline and return (before, after) gate counts. + /// Apply the full pipeline and return (before, after) gate-batch counts. fn pipeline_stats(tc: &mut TickCircuit) -> (usize, usize) { - let before = count_gates(tc); + let before = count_gate_batches(tc); MergeAdjacentRotations.apply_tick(tc); RemoveIdentity.apply_tick(tc); SimplifyRotations.apply_tick(tc); CancelInverses.apply_tick(tc); PeepholeOptimize.apply_tick(tc); - let after = count_gates(tc); + let after = count_gate_batches(tc); (before, after) } @@ -2844,14 +2844,14 @@ mod tests { let middle = tc .ticks() .iter() - .find(|tick| !tick.gates().is_empty()) + .find(|tick| !tick.gate_batches().is_empty()) .expect("peephole result should keep the middle tick"); assert_eq!(middle.len(), 2); assert_eq!(middle.gate_count(), 2); let mut saw_rewritten = false; let mut saw_untouched = false; - for (idx, gate) in middle.gates().iter().enumerate() { + for (idx, gate) in middle.gate_batches().iter().enumerate() { assert_eq!( middle.get_gate_attr(idx, "calibration"), Some(&Attribute::String("entangler".into())) @@ -3210,8 +3210,8 @@ mod tests { .then(MergeAdjacentRotations) .then(SimplifyRotations); pipeline.apply_tick(&mut tc); - assert_eq!(count_gates(&tc), 1); - assert_eq!(tc.ticks()[0].gates()[0].gate_type, GateType::SZ); + assert_eq!(count_gate_batches(&tc), 1); + assert_eq!(tc.ticks()[0].gate_batches()[0].gate_type, GateType::SZ); } #[test] @@ -3235,7 +3235,7 @@ mod tests { .then(CancelInverses); pipeline.apply_tick(&mut tc); // PZ stays, T and both RZs absorbed (after PZ), H+H cancelled, MZ stays - assert_eq!(count_gates(&tc), 2); // PZ + MZ + assert_eq!(count_gate_batches(&tc), 2); // PZ + MZ } #[test] @@ -3259,7 +3259,7 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().h(&[0]); pipeline.apply_tick(&mut tc); - assert_eq!(count_gates(&tc), 1); + assert_eq!(count_gate_batches(&tc), 1); } // ==================== CompactTicks tests ==================== @@ -3284,8 +3284,8 @@ mod tests { tc.tick().x(&[0]); CompactTicks.apply_tick(&mut tc); assert_eq!(tc.num_ticks(), 2); - assert_eq!(tc.ticks()[0].gates()[0].gate_type, GateType::H); - assert_eq!(tc.ticks()[1].gates()[0].gate_type, GateType::X); + assert_eq!(tc.ticks()[0].gate_batches()[0].gate_type, GateType::H); + assert_eq!(tc.ticks()[1].gate_batches()[0].gate_type, GateType::X); } #[test] @@ -3300,7 +3300,7 @@ mod tests { assert_eq!(tc.num_ticks(), 3); CompactTicks.apply_tick(&mut tc); assert_eq!(tc.num_ticks(), 1); - assert_eq!(tc.ticks()[0].gates()[0].gate_type, GateType::X); + assert_eq!(tc.ticks()[0].gate_batches()[0].gate_type, GateType::X); } #[test] @@ -3348,9 +3348,9 @@ mod tests { tc.tick().sz(&[0]); CompactTicks.apply_tick(&mut tc); assert_eq!(tc.num_ticks(), 3); // all same qubit, no compaction - assert_eq!(tc.ticks()[0].gates()[0].gate_type, GateType::H); - assert_eq!(tc.ticks()[1].gates()[0].gate_type, GateType::T); - assert_eq!(tc.ticks()[2].gates()[0].gate_type, GateType::SZ); + assert_eq!(tc.ticks()[0].gate_batches()[0].gate_type, GateType::H); + assert_eq!(tc.ticks()[1].gate_batches()[0].gate_type, GateType::T); + assert_eq!(tc.ticks()[2].gate_batches()[0].gate_type, GateType::SZ); } #[test] @@ -3371,6 +3371,6 @@ mod tests { // After absorb+cancel: PZ(0,1), X(0), MZ(0,1) // X(0) can't merge with PZ (qubit 0 busy) or MZ (qubit 0 busy). assert_eq!(tc.num_ticks(), 3); - assert_eq!(count_gates(&tc), 3); + assert_eq!(count_gate_batches(&tc), 3); } } diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index 7d74de549..697b8ae09 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -1700,7 +1700,7 @@ impl TickCircuit { /// Returns true if any tick contains an explicit channel operation. #[must_use] pub fn has_channel_operations(&self) -> bool { - self.iter_gates().any(Gate::is_channel) + self.iter_gate_batches().any(Gate::is_channel) } /// Iterate over all gates with their tick index. @@ -1780,7 +1780,8 @@ impl TickCircuit { /// assert_eq!(h_gates.len(), 1); // One Gate object with 3 qubits /// ``` pub fn iter_gates_by_type(&self, gate_type: GateType) -> impl Iterator { - self.iter_gates().filter(move |g| g.gate_type == gate_type) + self.iter_gate_batches() + .filter(move |g| g.gate_type == gate_type) } /// Get all qubits used in the circuit. @@ -1799,7 +1800,7 @@ impl TickCircuit { /// ``` #[must_use] pub fn all_qubits(&self) -> BTreeSet { - self.iter_gates() + self.iter_gate_batches() .flat_map(|gate| gate.qubits.iter().copied()) .collect() } @@ -1827,7 +1828,7 @@ impl TickCircuit { #[must_use] pub fn gate_counts_by_type(&self) -> BTreeMap { let mut counts = BTreeMap::new(); - for gate in self.iter_gates() { + for gate in self.iter_gate_batches() { *counts.entry(gate.gate_type).or_insert(0) += gate.num_gates(); } counts diff --git a/exp/pecos-eeg/src/builder.rs b/exp/pecos-eeg/src/builder.rs index c8d8efe76..71c89d57e 100644 --- a/exp/pecos-eeg/src/builder.rs +++ b/exp/pecos-eeg/src/builder.rs @@ -57,7 +57,7 @@ impl<'a> EegDemBuilder<'a> { #[must_use] pub fn build(&self) -> Vec { - let gates: Vec = self.tc.iter_gates().cloned().collect(); + let gates: Vec = self.tc.iter_gate_batches().cloned().collect(); let expanded = expand::expand_circuit(&gates); let result = circuit::analyze_expanded(&expanded.gates, &self.noise); let (detectors, observables) = build_detectors(self.tc, &expanded); @@ -85,7 +85,7 @@ impl<'a> EegDemBuilder<'a> { #[must_use] pub fn summary(&self) -> EegSummary { - let gates: Vec = self.tc.iter_gates().cloned().collect(); + let gates: Vec = self.tc.iter_gate_batches().cloned().collect(); let expanded = expand::expand_circuit(&gates); let result = circuit::analyze_expanded(&expanded.gates, &self.noise); let (detectors, observables) = build_detectors(self.tc, &expanded); @@ -281,7 +281,7 @@ mod tests { .build(); // Manual path - let gates: Vec = tc.iter_gates().cloned().collect(); + let gates: Vec = tc.iter_gate_batches().cloned().collect(); let expanded = expand::expand_circuit(&gates); let result = circuit::analyze_expanded(&expanded.gates, &noise); diff --git a/exp/pecos-eeg/tests/surface_code.rs b/exp/pecos-eeg/tests/surface_code.rs index fd1113127..f20577cab 100644 --- a/exp/pecos-eeg/tests/surface_code.rs +++ b/exp/pecos-eeg/tests/surface_code.rs @@ -33,7 +33,7 @@ fn build_repetition_code() -> (Vec, Vec, Vec) { // Final data readout tc.tick().mz(&[0, 1, 2]); - let gates: Vec = tc.iter_gates().cloned().collect(); + let gates: Vec = tc.iter_gate_batches().cloned().collect(); // Detector stabilizers: X on ancilla qubit (anticommutes with Z errors // that propagate through CX from data qubits). @@ -168,7 +168,7 @@ fn test_eeg_generator_count_scales_linearly() { } tc.tick().mz(&[0, 1, 2]); - let gates: Vec = tc.iter_gates().cloned().collect(); + let gates: Vec = tc.iter_gate_batches().cloned().collect(); let expanded = expand::expand_circuit(&gates); let noise = NoiseModel::coherent_only(0.1); let result = analyze_expanded(&expanded.gates, &noise); diff --git a/exp/pecos-neo/src/circuit.rs b/exp/pecos-neo/src/circuit.rs index e53a86f03..629c4b2b9 100644 --- a/exp/pecos-neo/src/circuit.rs +++ b/exp/pecos-neo/src/circuit.rs @@ -188,13 +188,13 @@ impl From for GateCommand { impl From<&TickCircuit> for CommandQueue { /// Convert a `TickCircuit` to a `CommandQueue`. /// - /// Gates are added in tick order - all gates from tick 0, then tick 1, etc. - /// Within each tick, gates are added in the order they appear. + /// Gate batches are added in tick order - all commands from tick 0, then tick 1, etc. + /// Within each tick, commands are added in the order they appear. fn from(circuit: &TickCircuit) -> Self { let mut queue = CommandQueue::new(); for tick in circuit.ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { queue.push(gate.into()); } } diff --git a/exp/pecos-neo/src/engines.rs b/exp/pecos-neo/src/engines.rs index 5bff6aa35..075e60269 100644 --- a/exp/pecos-neo/src/engines.rs +++ b/exp/pecos-neo/src/engines.rs @@ -138,7 +138,7 @@ impl CommandSource for TickCircuitEngine { self.current_tick += 1; let mut queue = CommandQueue::new(); - for gate in tick.gates() { + for gate in tick.gate_batches() { queue.push(gate.into()); } diff --git a/exp/pecos-neo/src/inline_channel.rs b/exp/pecos-neo/src/inline_channel.rs index 58524443c..1b09a4769 100644 --- a/exp/pecos-neo/src/inline_channel.rs +++ b/exp/pecos-neo/src/inline_channel.rs @@ -108,7 +108,7 @@ pub fn run_inline_channels_density_matrix( let mut row = Vec::new(); for tick in circuit.ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { row.extend(apply_gate_to_density_matrix(&mut sim, gate)?); } } @@ -145,7 +145,7 @@ pub fn run_inline_pauli_channels_stabilizer( let mut row = Vec::new(); for tick in circuit.ticks() { - for gate in tick.gates() { + for gate in tick.gate_batches() { row.extend(apply_gate_to_stabilizer_with_pauli_channels( &mut sim, gate, &mut rng, )?); diff --git a/exp/pecos-zx/src/viz/circuit_layout.rs b/exp/pecos-zx/src/viz/circuit_layout.rs index f44100f97..f5334f2d8 100644 --- a/exp/pecos-zx/src/viz/circuit_layout.rs +++ b/exp/pecos-zx/src/viz/circuit_layout.rs @@ -285,7 +285,7 @@ pub fn layout_from_tick_circuit(tc: &TickCircuit) -> CircuitLayout { if tick_idx >= num_steps { break; } - for gate in tick.gates().iter() { + for gate in tick.gate_batches().iter() { let qubit_indices: Vec = gate.qubits.iter().map(|q| q.index()).collect(); // TODO: TickCircuit classical bit/condition support diff --git a/python/pecos-rslib/src/dag_circuit_bindings.rs b/python/pecos-rslib/src/dag_circuit_bindings.rs index 26618fb27..5d5a1b4a9 100644 --- a/python/pecos-rslib/src/dag_circuit_bindings.rs +++ b/python/pecos-rslib/src/dag_circuit_bindings.rs @@ -2065,10 +2065,10 @@ impl PyTick { self.inner.is_empty() } - /// Get the gates in this tick as a list. + /// Get the stored gate commands in this tick as a list. fn gates(&self) -> Vec { self.inner - .gates() + .gate_batches() .iter() .map(|g: &Gate| PyGate { inner: g.clone() }) .collect() @@ -2421,13 +2421,13 @@ impl PyTickCircuit { Ok(dict.into()) } - /// Get all gates in the circuit as a list. + /// Get all stored gate commands in the circuit as a list. /// /// Returns: /// A list of (`tick_index`, gate) tuples. fn gates(&self) -> Vec<(usize, PyGate)> { self.inner - .iter_gates_with_tick() + .iter_gate_batches_with_tick() .map(|(tick_idx, gate)| { ( tick_idx, @@ -2636,7 +2636,7 @@ impl PyTickCircuit { } if p2 > 0.0 { - for (tick_idx, gate) in self.inner.iter_gates_with_tick() { + for (tick_idx, gate) in self.inner.iter_gate_batches_with_tick() { if receives_two_qubit_noise(gate.gate_type) && !gate.qubits.len().is_multiple_of(2) { return Err(pyo3::exceptions::PyValueError::new_err(format!( From 022f01dae93f8579867b42392d8bb29b99d4c619 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 12:06:06 -0600 Subject: [PATCH 107/125] Move Tick storage to internal SoA --- crates/pecos-quantum/src/pass.rs | 45 +++-- crates/pecos-quantum/src/tick_circuit.rs | 245 +++++++++++++++++++++-- 2 files changed, 255 insertions(+), 35 deletions(-) diff --git a/crates/pecos-quantum/src/pass.rs b/crates/pecos-quantum/src/pass.rs index b19f57d81..cbf228a76 100644 --- a/crates/pecos-quantum/src/pass.rs +++ b/crates/pecos-quantum/src/pass.rs @@ -532,8 +532,11 @@ impl CircuitPass for SimplifyRotations { } // Second pass: in-place simplification of remaining gates. - for gate in tick.gates_mut() { - simplify_gate_in_place(gate); + for gate_idx in 0..tick.len() { + tick.update_gate_batch(gate_idx, |gate| { + simplify_gate_in_place(gate); + }) + .unwrap_or_else(|err| panic!("{err}")); } } } @@ -775,10 +778,11 @@ impl CircuitPass for MergeAdjacentRotations { // Apply angle adjustments to surviving gates. for (&(ti, gi), &delta) in &angle_adjustments { - if let Some(tick) = circuit.get_tick_mut(ti) - && let Some(gate) = tick.gates_mut().get_mut(gi) - { - gate.angles[0] += delta; + if let Some(tick) = circuit.get_tick_mut(ti) { + tick.update_gate_batch(gi, |gate| { + gate.angles[0] += delta; + }) + .unwrap_or_else(|err| panic!("{err}")); } } @@ -912,11 +916,12 @@ impl CircuitPass for PeepholeOptimize { // Apply replacements. for ((ti, gi), new_gt, new_qubits) in &replacements { - if let Some(tick) = circuit.get_tick_mut(*ti) - && let Some(gate) = tick.gates_mut().get_mut(*gi) - { - gate.gate_type = *new_gt; - gate.qubits.clone_from(new_qubits); + if let Some(tick) = circuit.get_tick_mut(*ti) { + tick.update_gate_batch(*gi, |gate| { + gate.gate_type = *new_gt; + gate.qubits.clone_from(new_qubits); + }) + .unwrap_or_else(|err| panic!("{err}")); } } @@ -1260,14 +1265,18 @@ impl CircuitPass for AssignMissingMeasIds { fn apply_tick(&self, circuit: &mut TickCircuit) { let mut next_id = circuit.num_measurements(); for tick in circuit.ticks_mut() { - for gate in tick.gates_mut() { - let is_measurement = matches!(gate.gate_type, GateType::MZ | GateType::MeasureFree); - if is_measurement && gate.meas_ids.is_empty() { - for _ in &gate.qubits { - gate.meas_ids.push(pecos_core::MeasId(next_id)); - next_id += 1; + for gate_idx in 0..tick.len() { + tick.update_gate_batch(gate_idx, |gate| { + let is_measurement = + matches!(gate.gate_type, GateType::MZ | GateType::MeasureFree); + if is_measurement && gate.meas_ids.is_empty() { + for _ in &gate.qubits { + gate.meas_ids.push(pecos_core::MeasId(next_id)); + next_id += 1; + } } - } + }) + .unwrap_or_else(|err| panic!("{err}")); } } let added = next_id - circuit.num_measurements(); diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index 697b8ae09..181884377 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -64,13 +64,15 @@ use pecos_core::gate_type::GateType; use pecos_core::{ - Angle64, ChannelExpr, Gate, GateMeasIds, GateQubits, GateSignature, MeasId, QubitId, TimeUnits, + Angle64, ChannelExpr, Gate, GateAngles, GateMeasIds, GateParams, GateQubits, GateSignature, + MeasId, QubitId, TimeUnits, }; use std::collections::{BTreeMap, BTreeSet}; use crate::Attribute; use crate::dag_circuit::{AnnotationKind, DagCircuit, PauliAnnotation}; use std::fmt; +use std::ops::{Deref, Index}; fn meta_json_array(circuit: &TickCircuit, key: &str) -> Result, String> { let Some(attr) = circuit.get_meta(key) else { @@ -325,11 +327,107 @@ impl From for CustomGateError { } } +#[derive(Debug, Clone, Default)] +struct TickGateStorage { + gate_types: Vec, + angles: Vec, + params: Vec, + qubits: Vec, + meas_ids: Vec, + channels: Vec>, + materialized: Vec, +} + +impl TickGateStorage { + fn len(&self) -> usize { + self.gate_types.len() + } + + fn is_empty(&self) -> bool { + self.gate_types.is_empty() + } + + fn as_slice(&self) -> &[Gate] { + &self.materialized + } + + fn iter(&self) -> std::slice::Iter<'_, Gate> { + self.materialized.iter() + } + + fn get(&self, idx: usize) -> Option<&Gate> { + self.materialized.get(idx) + } + + fn push(&mut self, gate: Gate) { + self.gate_types.push(gate.gate_type); + self.angles.push(gate.angles.clone()); + self.params.push(gate.params.clone()); + self.qubits.push(gate.qubits.clone()); + self.meas_ids.push(gate.meas_ids.clone()); + self.channels.push(gate.channel.clone()); + self.materialized.push(gate); + } + + fn set(&mut self, idx: usize, gate: Gate) { + self.gate_types[idx] = gate.gate_type; + self.angles[idx].clone_from(&gate.angles); + self.params[idx].clone_from(&gate.params); + self.qubits[idx].clone_from(&gate.qubits); + self.meas_ids[idx].clone_from(&gate.meas_ids); + self.channels[idx].clone_from(&gate.channel); + self.materialized[idx] = gate; + } + + fn remove(&mut self, idx: usize) -> Gate { + self.gate_types.remove(idx); + self.angles.remove(idx); + self.params.remove(idx); + self.qubits.remove(idx); + self.meas_ids.remove(idx); + self.channels.remove(idx); + self.materialized.remove(idx) + } + + fn append_batch(&mut self, idx: usize, gate: Gate) { + assert!( + self.materialized[idx].can_batch_with(&gate), + "cannot batch incompatible gate commands" + ); + self.qubits[idx].extend(gate.qubits.iter().copied()); + self.meas_ids[idx].extend(gate.meas_ids.iter().copied()); + self.materialized[idx].append_batch(gate); + } + + fn truncate_payload(&mut self, idx: usize, qubit_len: usize, meas_id_len: usize) { + self.qubits[idx].truncate(qubit_len); + self.meas_ids[idx].truncate(meas_id_len); + self.materialized[idx].qubits.truncate(qubit_len); + self.materialized[idx].meas_ids.truncate(meas_id_len); + } +} + +impl Deref for TickGateStorage { + type Target = [Gate]; + + fn deref(&self) -> &Self::Target { + self.as_slice() + } +} + +impl Index for TickGateStorage { + type Output = Gate; + + fn index(&self, index: usize) -> &Self::Output { + &self.materialized[index] + } +} + /// A single time slice containing gates that execute in parallel. #[derive(Debug, Clone, Default)] pub struct Tick { /// Gate batches in this tick (all act on disjoint qubits). - gate_batches: Vec, + gate_batches: TickGateStorage, /// Metadata for each gate batch, indexed by position in `gate_batches`. gate_attrs: BTreeMap>, /// Tick-level metadata. @@ -400,7 +498,7 @@ impl Tick { /// execution/analyzer code where that distinction matters. #[must_use] pub fn gates(&self) -> &[Gate] { - &self.gate_batches + self.gate_batches.as_slice() } /// Get the full-fidelity gate batches in this tick. @@ -415,12 +513,7 @@ impl Tick { /// view cheaper or more data-oriented without changing consumers. #[must_use] pub fn gate_batches(&self) -> &[Gate] { - &self.gate_batches - } - - /// Get mutable access to the stored gate commands in this tick. - pub fn gates_mut(&mut self) -> &mut [Gate] { - &mut self.gate_batches + self.gate_batches.as_slice() } /// Add a gate to this tick. @@ -502,7 +595,7 @@ impl Tick { let qubit_start = self.gate_batches[target_idx].qubits.len(); let meas_id_start = self.gate_batches[target_idx].meas_ids.len(); let gate = self.gate_batches[piece.gate_idx].clone(); - self.gate_batches[target_idx].append_batch(gate); + self.gate_batches.append_batch(target_idx, gate); self.remove_gate(piece.gate_idx); GateBatchPiece { gate_idx: target_idx, @@ -552,12 +645,8 @@ impl Tick { split_gate.meas_ids = self.gate_batches[piece.gate_idx].meas_ids[piece.meas_id_start..].into(); - self.gate_batches[piece.gate_idx] - .qubits - .truncate(piece.qubit_start); - self.gate_batches[piece.gate_idx] - .meas_ids - .truncate(piece.meas_id_start); + self.gate_batches + .truncate_payload(piece.gate_idx, piece.qubit_start, piece.meas_id_start); let split_idx = self.push_gate_unchecked(split_gate); if let Some(attrs) = self.gate_attrs.get(&piece.gate_idx).cloned() { @@ -731,12 +820,81 @@ impl Tick { meas_id_start: self.gate_batches[gate_idx].meas_ids.len(), meas_id_len: gate.meas_ids.len(), }; - self.gate_batches[gate_idx].append_batch(gate); + self.gate_batches.append_batch(gate_idx, gate); return Ok(piece); } Ok(self.push_gate_unchecked_piece(gate)) } + /// Replace a stored gate batch while preserving storage invariants. + /// + /// # Errors + /// + /// Returns [`TickGateError::InvalidGate`] if `gate_idx` is out of bounds or + /// if the replacement gate payload is invalid. Returns + /// [`TickGateError::QubitConflict`] if the replacement overlaps another + /// command in this tick. + pub fn replace_gate_batch(&mut self, gate_idx: usize, gate: Gate) -> Result<(), TickGateError> { + if gate_idx >= self.gate_batches.len() { + return Err(TickGateError::InvalidGate { + message: format!("gate index {gate_idx} out of bounds"), + tick_idx: None, + }); + } + gate.validate() + .map_err(|message| TickGateError::InvalidGate { + message, + tick_idx: None, + })?; + + let mut active = BTreeSet::new(); + for (idx, existing) in self.gate_batches.iter().enumerate() { + if idx == gate_idx { + continue; + } + active.extend(existing.qubits.iter().copied()); + } + let conflicts: Vec = gate + .qubits + .iter() + .filter(|q| active.contains(q)) + .copied() + .collect(); + if !conflicts.is_empty() { + return Err(TickGateError::QubitConflict(QubitConflictError { + conflicting_qubits: conflicts, + tick_idx: None, + })); + } + + self.gate_batches.set(gate_idx, gate); + Ok(()) + } + + /// Mutate a stored gate batch through a temporary [`Gate`] value. + /// + /// This keeps the internal `SoA` storage synchronized with the materialized + /// compatibility view returned by [`gate_batches`](Self::gate_batches). + /// + /// # Errors + /// + /// Propagates the same errors as [`replace_gate_batch`](Self::replace_gate_batch). + pub fn update_gate_batch( + &mut self, + gate_idx: usize, + update: impl FnOnce(&mut Gate), + ) -> Result<(), TickGateError> { + let Some(existing) = self.gate_batches.get(gate_idx) else { + return Err(TickGateError::InvalidGate { + message: format!("gate index {gate_idx} out of bounds"), + tick_idx: None, + }); + }; + let mut gate = existing.clone(); + update(&mut gate); + self.replace_gate_batch(gate_idx, gate) + } + /// Remove all gates that use any of the specified qubits. /// /// Returns the number of gates removed. @@ -3209,6 +3367,59 @@ mod tests { ); } + #[test] + fn test_tick_replace_gate_batch_updates_stored_views() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[0]).h(&[1]); + + let tick = tc.get_tick_mut(0).unwrap(); + tick.replace_gate_batch(0, Gate::x(&[0, 1])) + .expect("same support replacement should be valid"); + + assert_eq!(tick.len(), 1); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batches()[0].gate_type, GateType::X); + assert_eq!( + tick.gate_batches()[0].qubits.as_slice(), + &[QubitId::from(0), QubitId::from(1)] + ); + assert_eq!(tick.gates()[0], tick.gate_batches()[0]); + } + + #[test] + fn test_tick_replace_gate_batch_rejects_overlapping_qubits() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[0]).x(&[1]); + + let tick = tc.get_tick_mut(0).unwrap(); + let err = tick + .replace_gate_batch(0, Gate::z(&[1])) + .expect_err("replacement overlaps the X command on q1"); + + assert!(matches!(err, TickGateError::QubitConflict(_))); + assert_eq!(tick.gate_batches()[0].gate_type, GateType::H); + assert_eq!(tick.gate_batches()[1].gate_type, GateType::X); + } + + #[test] + fn test_tick_update_gate_batch_keeps_measurement_ids_in_sync() { + let mut tc = TickCircuit::new(); + tc.tick().mz(&[0, 1]); + + let tick = tc.get_tick_mut(0).unwrap(); + tick.update_gate_batch(0, |gate| { + gate.meas_ids[0] = MeasId(10); + gate.meas_ids[1] = MeasId(11); + }) + .expect("measurement id update should be valid"); + + assert_eq!( + tick.gate_batches()[0].meas_ids.as_slice(), + &[MeasId(10), MeasId(11)] + ); + assert_eq!(tick.gates()[0].meas_ids, tick.gate_batches()[0].meas_ids); + } + #[test] fn test_tick_construction_batches_only_same_metadata() { let mut same = TickCircuit::new(); From 587858592eec26949c601c01c61b4a945f51e404 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 12:20:31 -0600 Subject: [PATCH 108/125] Expose explicit Python gate_batches access --- python/pecos-rslib-exp/src/eeg_bindings.rs | 2 +- python/pecos-rslib-exp/src/sim_neo_bindings.rs | 6 +++--- python/pecos-rslib/src/dag_circuit_bindings.rs | 8 ++++---- .../quantum-pecos/src/pecos/circuits/quantum_circuit.py | 6 +++--- .../src/pecos/qec/surface/circuit_builder.py | 6 +++--- .../src/pecos/qec/surface/logical_circuit.py | 4 ++-- .../quantum-pecos/tests/qec/surface/test_circuit_fuzz.py | 4 ++-- .../tests/qec/surface/test_surface_metadata.py | 2 +- .../quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py | 2 +- .../tests/qec/test_inline_channel_sim_neo.py | 2 +- 10 files changed, 21 insertions(+), 21 deletions(-) diff --git a/python/pecos-rslib-exp/src/eeg_bindings.rs b/python/pecos-rslib-exp/src/eeg_bindings.rs index 110642764..c47445fc5 100644 --- a/python/pecos-rslib-exp/src/eeg_bindings.rs +++ b/python/pecos-rslib-exp/src/eeg_bindings.rs @@ -1104,7 +1104,7 @@ fn extract_gates(py_tc: &Bound<'_, PyAny>) -> PyResult> { for tick_idx in 0..num_ticks { let py_tick = py_tc.call_method1("get_tick", (tick_idx,))?; - let py_gates = py_tick.call_method0("gates")?; + let py_gates = py_tick.call_method0("gate_batches")?; let gate_list: Vec> = py_gates.extract()?; // Collect all gates in this tick first, then emit them. diff --git a/python/pecos-rslib-exp/src/sim_neo_bindings.rs b/python/pecos-rslib-exp/src/sim_neo_bindings.rs index 666784395..96522500b 100644 --- a/python/pecos-rslib-exp/src/sim_neo_bindings.rs +++ b/python/pecos-rslib-exp/src/sim_neo_bindings.rs @@ -897,7 +897,7 @@ fn build_rust_tick_circuit_from_gates( for tick_idx in 0..num_ticks { let py_tick = py_tc.call_method1("get_tick", (tick_idx,))?; - let py_gates = py_tick.call_method0("gates")?; + let py_gates = py_tick.call_method0("gate_batches")?; let gates: Vec> = py_gates.extract()?; // Separate gates by type: MZ, PZ, and other @@ -1184,14 +1184,14 @@ fn build_gate_from_python( // Circuit extraction // ============================================================================ -/// Extract a CommandQueue from a Python TickCircuit by iterating its gates. +/// Extract a CommandQueue from a Python TickCircuit by iterating its stored gate batches. fn extract_commands(py_tc: &Bound<'_, PyAny>) -> PyResult { let num_ticks: usize = py_tc.call_method0("num_ticks")?.extract()?; let mut cb = CommandBuilder::new(); for tick_idx in 0..num_ticks { let py_tick = py_tc.call_method1("get_tick", (tick_idx,))?; - let py_gates = py_tick.call_method0("gates")?; + let py_gates = py_tick.call_method0("gate_batches")?; let gates: Vec> = py_gates.extract()?; for gate in &gates { diff --git a/python/pecos-rslib/src/dag_circuit_bindings.rs b/python/pecos-rslib/src/dag_circuit_bindings.rs index 5d5a1b4a9..cb7229ad8 100644 --- a/python/pecos-rslib/src/dag_circuit_bindings.rs +++ b/python/pecos-rslib/src/dag_circuit_bindings.rs @@ -2065,8 +2065,8 @@ impl PyTick { self.inner.is_empty() } - /// Get the stored gate commands in this tick as a list. - fn gates(&self) -> Vec { + /// Get the stored gate batches in this tick as a list. + fn gate_batches(&self) -> Vec { self.inner .gate_batches() .iter() @@ -2421,11 +2421,11 @@ impl PyTickCircuit { Ok(dict.into()) } - /// Get all stored gate commands in the circuit as a list. + /// Get all stored gate batches in the circuit as a list. /// /// Returns: /// A list of (`tick_index`, gate) tuples. - fn gates(&self) -> Vec<(usize, PyGate)> { + fn gate_batches(&self) -> Vec<(usize, PyGate)> { self.inner .iter_gate_batches_with_tick() .map(|(tick_idx, gate)| { diff --git a/python/quantum-pecos/src/pecos/circuits/quantum_circuit.py b/python/quantum-pecos/src/pecos/circuits/quantum_circuit.py index 19ef17633..ae03fb7bf 100644 --- a/python/quantum-pecos/src/pecos/circuits/quantum_circuit.py +++ b/python/quantum-pecos/src/pecos/circuits/quantum_circuit.py @@ -159,7 +159,7 @@ def active_qudits(self) -> list[set[int]]: if tick is not None: # Get individual qubits from all gates in the tick active: set[int] = set() - for gate in tick.gates(): + for gate in tick.gate_batches(): for q in gate.qubits: active.add(q) result.append(active) @@ -380,7 +380,7 @@ def _iter_tick( # Use a dict to preserve insertion order and group gates grouped: dict[tuple[str, str], tuple[set[Location], JSONDict]] = {} - for gate_idx, gate in enumerate(tick_obj.gates()): + for gate_idx, gate in enumerate(tick_obj.gate_batches()): # Check for stored original symbol in metadata stored_symbol = tick_obj.get_gate_attr(gate_idx, "_symbol") @@ -769,7 +769,7 @@ def active_qudits(self) -> set[Location]: return set() active: set[Location] = set() - for gate in tick.gates(): + for gate in tick.gate_batches(): qubits = list(gate.qubits) if len(qubits) == 1: active.add(qubits[0]) diff --git a/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py b/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py index c66708667..a533f4b68 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py +++ b/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py @@ -1704,7 +1704,7 @@ def _gate_to_stim( for tick_idx in range(tc.num_ticks()): tick = tc.get_tick(tick_idx) - for gate in tick.gates(): + for gate in tick.gate_batches(): instructions, noise_kind = _gate_to_stim(gate) if not instructions: continue @@ -1859,7 +1859,7 @@ def generate_dem_from_tick_circuit_via_pauli_frame( for tick_idx in range(tc.num_ticks()): tick = tc.get_tick(tick_idx) - for gate in tick.gates(): + for gate in tick.gate_batches(): gate_name = gate.gate_type.name qubits = list(gate.qubits) meas_idx = None @@ -2132,7 +2132,7 @@ def _extract_measurement_order(tc: TickCircuit) -> list[int]: tick = tc.get_tick(tick_idx) if tick is None: continue - gates = tick.gates() + gates = tick.gate_batches() for gate in gates: gate_type = str(gate.gate_type) if "MZ" in gate_type: diff --git a/python/quantum-pecos/src/pecos/qec/surface/logical_circuit.py b/python/quantum-pecos/src/pecos/qec/surface/logical_circuit.py index 82384bd88..c5d10a619 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/logical_circuit.py +++ b/python/quantum-pecos/src/pecos/qec/surface/logical_circuit.py @@ -584,7 +584,7 @@ def build_dem( meas_order = [] for tick_idx in range(tc.num_ticks()): tick = tc.get_tick(tick_idx) - for gate in tick.gates(): + for gate in tick.gate_batches(): if gate.gate_type.name == "MZ": meas_order.extend(int(q) for q in gate.qubits) @@ -626,7 +626,7 @@ def build_sampler_and_decoder( meas_order = [] for tick_idx in range(tc.num_ticks()): tick = tc.get_tick(tick_idx) - for gate in tick.gates(): + for gate in tick.gate_batches(): if gate.gate_type.name == "MZ": meas_order.extend(int(q) for q in gate.qubits) diff --git a/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py b/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py index d96429b89..47f4079a0 100644 --- a/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py +++ b/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py @@ -33,7 +33,7 @@ def simulate_tick_circuit(tc: TickCircuit, seed: int = 0) -> tuple[list[int], in """ max_q = 0 for i in range(tc.num_ticks()): - for g in tc.get_tick(i).gates(): + for g in tc.get_tick(i).gate_batches(): for q in g.qubits: max_q = max(max_q, int(q)) @@ -42,7 +42,7 @@ def simulate_tick_circuit(tc: TickCircuit, seed: int = 0) -> tuple[list[int], in flat = [] for i in range(tc.num_ticks()): - for g in tc.get_tick(i).gates(): + for g in tc.get_tick(i).gate_batches(): name = g.gate_type.name qs = [int(q) for q in g.qubits] if name == "QAlloc": diff --git a/python/quantum-pecos/tests/qec/surface/test_surface_metadata.py b/python/quantum-pecos/tests/qec/surface/test_surface_metadata.py index 077110f7f..f5f7fa606 100644 --- a/python/quantum-pecos/tests/qec/surface/test_surface_metadata.py +++ b/python/quantum-pecos/tests/qec/surface/test_surface_metadata.py @@ -210,7 +210,7 @@ def test_tick_circuit_exposes_measurement_order() -> None: tick = tc.get_tick(tick_index) if tick is None: continue - for gate in tick.gates(): + for gate in tick.gate_batches(): if "MZ" not in str(gate.gate_type): continue for qubit in gate.qubits: diff --git a/python/quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py b/python/quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py index 3c4e77d9f..e21072a7f 100644 --- a/python/quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py +++ b/python/quantum-pecos/tests/qec/test_dem_sampler_vs_stim.py @@ -39,7 +39,7 @@ def extract_measurement_order(tc: "TickCircuit") -> list[int]: tick = tc.get_tick(tick_idx) if tick is None: continue - for gate in tick.gates(): + for gate in tick.gate_batches(): gate_type = str(gate.gate_type) if "MZ" in gate_type: for qubit in gate.qubits: diff --git a/python/quantum-pecos/tests/qec/test_inline_channel_sim_neo.py b/python/quantum-pecos/tests/qec/test_inline_channel_sim_neo.py index 69555febb..242cbdcbb 100644 --- a/python/quantum-pecos/tests/qec/test_inline_channel_sim_neo.py +++ b/python/quantum-pecos/tests/qec/test_inline_channel_sim_neo.py @@ -21,7 +21,7 @@ def measurement_rows(result) -> list[list[int]]: def test_tick_circuit_with_noise_inserts_channel_payload() -> None: noisy = prep_measure_circuit().with_noise(p_prep=1.0) - channel_gates = [gate for _, gate in noisy.gates() if gate.is_channel()] + channel_gates = [gate for _, gate in noisy.gate_batches() if gate.is_channel()] assert len(channel_gates) == 1 assert channel_gates[0].channel_mixed_pauli_terms() == [ From 90a1a036a2489e501ac86fd51c167c490ae65c7d Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 12:43:10 -0600 Subject: [PATCH 109/125] Remove TickCircuit gate alias APIs --- crates/pecos-quantum/src/pass.rs | 18 +- crates/pecos-quantum/src/tick_circuit.rs | 172 ++++++------------ docs/user-guide/circuit-representation.md | 7 +- .../pecos-rslib/src/dag_circuit_bindings.rs | 17 +- .../user_guide_circuit_representation.rs | 1 + .../tests/qec/surface/test_circuit_fuzz.py | 14 ++ 6 files changed, 103 insertions(+), 126 deletions(-) diff --git a/crates/pecos-quantum/src/pass.rs b/crates/pecos-quantum/src/pass.rs index cbf228a76..1ffc86df1 100644 --- a/crates/pecos-quantum/src/pass.rs +++ b/crates/pecos-quantum/src/pass.rs @@ -2385,7 +2385,7 @@ mod tests { let gate = tc .ticks() .iter() - .flat_map(super::super::tick_circuit::Tick::gates) + .flat_map(super::super::tick_circuit::Tick::gate_batches) .next() .unwrap(); assert_eq!(gate.gate_type, GateType::RZ); @@ -2402,7 +2402,7 @@ mod tests { let gate = tc .ticks() .iter() - .flat_map(super::super::tick_circuit::Tick::gates) + .flat_map(super::super::tick_circuit::Tick::gate_batches) .next() .unwrap(); assert_eq!(gate.gate_type, GateType::RZ); @@ -2418,7 +2418,7 @@ mod tests { let gate = tc .ticks() .iter() - .flat_map(super::super::tick_circuit::Tick::gates) + .flat_map(super::super::tick_circuit::Tick::gate_batches) .next() .unwrap(); assert_eq!(gate.gate_type, GateType::RZ); @@ -2434,7 +2434,7 @@ mod tests { let gate = tc .ticks() .iter() - .flat_map(super::super::tick_circuit::Tick::gates) + .flat_map(super::super::tick_circuit::Tick::gate_batches) .next() .unwrap(); assert_eq!(gate.gate_type, GateType::RZZ); @@ -2776,7 +2776,7 @@ mod tests { let gates: Vec<&Gate> = tc .ticks() .iter() - .flat_map(super::super::tick_circuit::Tick::gates) + .flat_map(super::super::tick_circuit::Tick::gate_batches) .collect(); assert_eq!(gates.len(), 1); assert_eq!(gates[0].gate_type, GateType::CZ); @@ -2794,7 +2794,7 @@ mod tests { let gates: Vec<&Gate> = tc .ticks() .iter() - .flat_map(super::super::tick_circuit::Tick::gates) + .flat_map(super::super::tick_circuit::Tick::gate_batches) .collect(); assert_eq!(gates.len(), 1); assert_eq!(gates[0].gate_type, GateType::CX); @@ -2813,7 +2813,7 @@ mod tests { let gates: Vec<&Gate> = tc .ticks() .iter() - .flat_map(super::super::tick_circuit::Tick::gates) + .flat_map(super::super::tick_circuit::Tick::gate_batches) .collect(); assert_eq!(gates.len(), 3); // unchanged } @@ -2831,7 +2831,7 @@ mod tests { let gates: Vec<&Gate> = tc .ticks() .iter() - .flat_map(super::super::tick_circuit::Tick::gates) + .flat_map(super::super::tick_circuit::Tick::gate_batches) .collect(); assert_eq!(gates.len(), 3); // X, CZ, Z assert_eq!(gates[0].gate_type, GateType::X); @@ -2898,7 +2898,7 @@ mod tests { let gates: Vec<&Gate> = tc .ticks() .iter() - .flat_map(super::super::tick_circuit::Tick::gates) + .flat_map(super::super::tick_circuit::Tick::gate_batches) .collect(); assert_eq!(gates.len(), 2); assert!(gates.iter().all(|g| g.gate_type == GateType::CZ)); diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index 181884377..3d433b056 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -392,7 +392,7 @@ impl TickGateStorage { fn append_batch(&mut self, idx: usize, gate: Gate) { assert!( self.materialized[idx].can_batch_with(&gate), - "cannot batch incompatible gate commands" + "cannot merge incompatible gate batches" ); self.qubits[idx].extend(gate.qubits.iter().copied()); self.meas_ids[idx].extend(gate.meas_ids.iter().copied()); @@ -452,8 +452,8 @@ impl Tick { /// Get the number of gates in this tick. /// - /// This is the number of stored gate commands. Batched commands such as - /// `cx(&[(0, 1), (2, 3)])` count as one stored command. + /// This is the number of stored gate batches. Batched commands such as + /// `cx(&[(0, 1), (2, 3)])` count as one stored batch. #[must_use] pub fn len(&self) -> usize { self.gate_batches.len() @@ -491,26 +491,14 @@ impl Tick { self.gate_batches.is_empty() } - /// Get the stored gate commands in this tick. - /// - /// A stored command may be a batch containing multiple gate applications on - /// disjoint qubits. Prefer [`gate_batches`](Self::gate_batches) in - /// execution/analyzer code where that distinction matters. - #[must_use] - pub fn gates(&self) -> &[Gate] { - self.gate_batches.as_slice() - } - /// Get the full-fidelity gate batches in this tick. /// /// In `TickCircuit`, a stored [`Gate`] command may represent one or more /// gate applications on disjoint qubits. For example, /// `cx(&[(0, 1), (2, 3)])` is one batch and two gate applications. /// - /// This is intentionally the same data as [`gates`](Self::gates) today: the - /// batches preserve the complete [`Gate`] payload, including measurement - /// IDs and typed channel payloads. Future internal storage can make this - /// view cheaper or more data-oriented without changing consumers. + /// The batches preserve the complete [`Gate`] payload, including + /// measurement IDs and typed channel payloads. #[must_use] pub fn gate_batches(&self) -> &[Gate] { self.gate_batches.as_slice() @@ -1234,7 +1222,7 @@ impl TickCircuit { /// Convert a per-tick gate index to a global gate index. /// - /// Global index = sum of stored gate commands for all ticks before + /// Global index = sum of stored gate batches for all ticks before /// `tick_idx` + `gate_idx`. #[must_use] pub fn global_gate_index(&self, tick_idx: usize, gate_idx: usize) -> usize { @@ -1821,31 +1809,6 @@ impl TickCircuit { // --- Iteration helpers --- - /// Iterate over all stored gate commands in the circuit, across all ticks. - /// - /// A yielded command may be a batch containing multiple gate applications - /// on disjoint qubits. Prefer [`iter_gate_batches`](Self::iter_gate_batches) - /// in execution/analyzer code where that distinction matters. - /// - /// Commands are yielded in tick order, then in order within each tick. - /// - /// # Examples - /// - /// ``` - /// use pecos_quantum::TickCircuit; - /// - /// let mut circuit = TickCircuit::new(); - /// circuit.tick().h(&[0, 1]); - /// circuit.tick().cx(&[(0, 1)]); - /// - /// for gate in circuit.iter_gates() { - /// println!("{:?} on {:?}", gate.gate_type, gate.qubits); - /// } - /// ``` - pub fn iter_gates(&self) -> impl Iterator { - self.ticks.iter().flat_map(Tick::gates) - } - /// Iterate over full-fidelity gate batches in the circuit. /// /// This is the preferred API for consumers that execute or analyze batched @@ -1861,29 +1824,6 @@ impl TickCircuit { self.iter_gate_batches().any(Gate::is_channel) } - /// Iterate over all gates with their tick index. - /// - /// Yields `(tick_index, gate)` pairs. - /// - /// # Examples - /// - /// ``` - /// use pecos_quantum::TickCircuit; - /// - /// let mut circuit = TickCircuit::new(); - /// circuit.tick().h(&[0]); - /// circuit.tick().x(&[0]); - /// - /// for (tick_idx, gate) in circuit.iter_gates_with_tick() { - /// println!("Tick {}: {:?}", tick_idx, gate.gate_type); - /// } - /// ``` - pub fn iter_gates_with_tick(&self) -> impl Iterator { - self.ticks.iter().enumerate().flat_map(|(tick_idx, tick)| { - tick.gate_batches().iter().map(move |gate| (tick_idx, gate)) - }) - } - /// Iterate over full-fidelity gate batches with their tick index. pub fn iter_gate_batches_with_tick(&self) -> impl Iterator { self.ticks.iter().enumerate().flat_map(|(tick_idx, tick)| { @@ -1914,7 +1854,7 @@ impl TickCircuit { /// Iterate over ticks through the batched command view. /// /// This is currently equivalent to [`iter_ticks`](Self::iter_ticks), because - /// each [`Tick`] stores full-fidelity batched gate commands. It exists so + /// each [`Tick`] stores full-fidelity gate batches. It exists so /// batched consumers can depend on `TickCircuit` directly instead of a /// converted execution-only circuit representation. pub fn iter_ticks_batched(&self) -> impl Iterator { @@ -3383,7 +3323,6 @@ mod tests { tick.gate_batches()[0].qubits.as_slice(), &[QubitId::from(0), QubitId::from(1)] ); - assert_eq!(tick.gates()[0], tick.gate_batches()[0]); } #[test] @@ -3417,7 +3356,6 @@ mod tests { tick.gate_batches()[0].meas_ids.as_slice(), &[MeasId(10), MeasId(11)] ); - assert_eq!(tick.gates()[0].meas_ids, tick.gate_batches()[0].meas_ids); } #[test] @@ -3912,11 +3850,11 @@ mod tests { // First tick should have H and X (order may vary) let tick0 = tc.get_tick(0).unwrap(); - assert_eq!(tick0.gates().len(), 2); + assert_eq!(tick0.gate_batches().len(), 2); // Second tick should have CX let tick1 = tc.get_tick(1).unwrap(); - assert_eq!(tick1.gates().len(), 1); + assert_eq!(tick1.gate_batches().len(), 1); // Check circuit attribute assert_eq!(tc.get_meta("version"), Some(&Attribute::Int(1))); @@ -3937,8 +3875,8 @@ mod tests { assert_eq!(tc1.num_ticks(), tc2.num_ticks()); for i in 0..tc1.num_ticks() { assert_eq!( - tc1.get_tick(i).unwrap().gates().len(), - tc2.get_tick(i).unwrap().gates().len() + tc1.get_tick(i).unwrap().gate_batches().len(), + tc2.get_tick(i).unwrap().gate_batches().len() ); } } @@ -4005,7 +3943,7 @@ mod tests { assert_eq!(tick0.len(), 1); assert_eq!(tick0.gate_count(), 2); assert_eq!(tick0.gate_batch_count(), 1); - assert_eq!(tick0.gates()[0].gate_type, GateType::H); + assert_eq!(tick0.gate_batches()[0].gate_type, GateType::H); assert_eq!( tick0.get_gate_attr(0, "calibration"), Some(&Attribute::String("h-cal".into())) @@ -4015,7 +3953,7 @@ mod tests { assert_eq!(tick1.len(), 1); assert_eq!(tick1.gate_count(), 2); assert_eq!(tick1.gate_batch_count(), 1); - assert_eq!(tick1.gates()[0].gate_type, GateType::CX); + assert_eq!(tick1.gate_batches()[0].gate_type, GateType::CX); assert_eq!( tick1.get_gate_attr(0, "calibration"), Some(&Attribute::String("cx-cal".into())) @@ -4025,9 +3963,9 @@ mod tests { assert_eq!(tick2.len(), 1); assert_eq!(tick2.gate_count(), 2); assert_eq!(tick2.gate_batch_count(), 1); - assert_eq!(tick2.gates()[0].gate_type, GateType::MZ); + assert_eq!(tick2.gate_batches()[0].gate_type, GateType::MZ); assert_eq!( - tick2.gates()[0].meas_ids.as_slice(), + tick2.gate_batches()[0].meas_ids.as_slice(), &[MeasId(0), MeasId(1)] ); } @@ -4139,7 +4077,7 @@ mod tests { let tc2 = TickCircuit::from(&dag); assert_eq!(tc2.gate_count(), 1); assert_eq!(tc2.gate_batch_count(), 1); - let gate = &tc2.get_tick(0).unwrap().gates()[0]; + let gate = &tc2.get_tick(0).unwrap().gate_batches()[0]; assert!(gate.is_channel()); assert_eq!( gate.qubits.as_slice(), @@ -4297,7 +4235,7 @@ mod tests { fn measurement_ids(circuit: &TickCircuit) -> Vec { circuit - .iter_gates() + .iter_gate_batches() .flat_map(|gate| gate.meas_ids.iter().copied()) .collect() } @@ -4442,7 +4380,7 @@ mod tests { fn channel_payloads(circuit: &TickCircuit) -> Vec { circuit - .iter_gates() + .iter_gate_batches() .filter_map(|gate| gate.channel.clone()) .collect() } @@ -5110,24 +5048,13 @@ mod tests { tc.tick().cx(&[(0, 1), (2, 3)]); tc.tick().mz(&[0, 1, 2, 3]); - // Test iter_gates - let gates: Vec<_> = tc.iter_gates().collect(); - assert_eq!(gates.len(), 3); - - // Test explicit batched views. These currently mirror the stored gate - // commands and preserve full Gate payloads. + // Test explicit batched views. These preserve full Gate payloads. let batches: Vec<_> = tc.iter_gate_batches().collect(); assert_eq!(batches.len(), 3); assert_eq!(batches[0].gate_type, GateType::H); assert_eq!(batches[0].num_gates(), 4); assert_eq!(tc.get_tick(0).unwrap().gate_batches()[0].num_gates(), 4); - // Test iter_gates_with_tick - let gates_with_tick: Vec<_> = tc.iter_gates_with_tick().collect(); - assert_eq!(gates_with_tick.len(), 3); - assert_eq!(gates_with_tick[0].0, 0); // First gate is in tick 0 - assert_eq!(gates_with_tick[1].0, 1); // Second gate is in tick 1 - let batches_with_tick: Vec<_> = tc.iter_gate_batches_with_tick().collect(); assert_eq!(batches_with_tick.len(), 3); assert_eq!(batches_with_tick[2].0, 2); // Third batch is in tick 2 @@ -5306,13 +5233,13 @@ mod tests { // Check order: H at 0, X at 1, CX at 2 let tick0 = tc.get_tick(0).unwrap(); - assert_eq!(tick0.gates()[0].gate_type, GateType::H); + assert_eq!(tick0.gate_batches()[0].gate_type, GateType::H); let tick1 = tc.get_tick(1).unwrap(); - assert_eq!(tick1.gates()[0].gate_type, GateType::X); + assert_eq!(tick1.gate_batches()[0].gate_type, GateType::X); let tick2 = tc.get_tick(2).unwrap(); - assert_eq!(tick2.gates()[0].gate_type, GateType::CX); + assert_eq!(tick2.gate_batches()[0].gate_type, GateType::CX); } #[test] @@ -5327,7 +5254,7 @@ mod tests { // Z should now be at tick 0 let tick0 = tc.get_tick(0).unwrap(); - assert_eq!(tick0.gates()[0].gate_type, GateType::Z); + assert_eq!(tick0.gate_batches()[0].gate_type, GateType::Z); } #[test] @@ -5341,7 +5268,7 @@ mod tests { assert_eq!(tc.num_ticks(), 2); let tick1 = tc.get_tick(1).unwrap(); - assert_eq!(tick1.gates()[0].gate_type, GateType::X); + assert_eq!(tick1.gate_batches()[0].gate_type, GateType::X); } #[test] @@ -5357,9 +5284,18 @@ mod tests { assert_eq!(tc.num_ticks(), 3); // Check each tick has the right gate - assert_eq!(tc.get_tick(0).unwrap().gates()[0].gate_type, GateType::H); - assert_eq!(tc.get_tick(1).unwrap().gates()[0].gate_type, GateType::X); - assert_eq!(tc.get_tick(2).unwrap().gates()[0].gate_type, GateType::CX); + assert_eq!( + tc.get_tick(0).unwrap().gate_batches()[0].gate_type, + GateType::H + ); + assert_eq!( + tc.get_tick(1).unwrap().gate_batches()[0].gate_type, + GateType::X + ); + assert_eq!( + tc.get_tick(2).unwrap().gate_batches()[0].gate_type, + GateType::CX + ); } #[test] @@ -5766,7 +5702,7 @@ mod tests { tc.tick() .channel(pecos_core::channel::Depolarizing(0.25, 0)); - let gate = &tc.get_tick(0).unwrap().gates()[0]; + let gate = &tc.get_tick(0).unwrap().gate_batches()[0]; assert_eq!(gate.gate_type, GateType::Channel); assert_eq!(gate.qubits.as_slice(), &[QubitId::from(0)]); assert!(gate.channel_expr().is_some()); @@ -5788,24 +5724,27 @@ mod tests { }); assert_eq!(noisy.num_ticks(), 4); - assert_eq!(noisy.get_tick(0).unwrap().gates()[0].gate_type, GateType::H); + assert_eq!( + noisy.get_tick(0).unwrap().gate_batches()[0].gate_type, + GateType::H + ); assert!( noisy .get_tick(1) .unwrap() - .gates() + .gate_batches() .iter() .all(Gate::is_channel) ); assert_eq!( - noisy.get_tick(2).unwrap().gates()[0].gate_type, + noisy.get_tick(2).unwrap().gate_batches()[0].gate_type, GateType::CX ); assert!( noisy .get_tick(3) .unwrap() - .gates() + .gate_batches() .iter() .all(Gate::is_channel) ); @@ -5912,8 +5851,10 @@ mod tests { for tick_idx in 0..tc.num_ticks() { let original = tc.get_tick(tick_idx).unwrap(); let copied = noisy.get_tick(tick_idx).unwrap(); - assert_eq!(copied.gates().len(), original.gates().len()); - for (copied_gate, original_gate) in copied.gates().iter().zip(original.gates()) { + assert_eq!(copied.gate_batches().len(), original.gate_batches().len()); + for (copied_gate, original_gate) in + copied.gate_batches().iter().zip(original.gate_batches()) + { assert_eq!(copied_gate.gate_type, original_gate.gate_type); assert_eq!(copied_gate.qubits, original_gate.qubits); assert!(!copied_gate.is_channel()); @@ -5934,7 +5875,10 @@ mod tests { }); assert_eq!(noisy.num_ticks(), 3); - assert_eq!(noisy.get_tick(0).unwrap().gates()[0].gate_type, GateType::H); + assert_eq!( + noisy.get_tick(0).unwrap().gate_batches()[0].gate_type, + GateType::H + ); let first_noise_tick = noisy.get_tick(1).unwrap(); assert_eq!(first_noise_tick.gate_batches().len(), 1); @@ -5968,10 +5912,10 @@ mod tests { assert_eq!(noisy.num_ticks(), 2); assert_eq!( - noisy.get_tick(0).unwrap().gates()[0].gate_type, + noisy.get_tick(0).unwrap().gate_batches()[0].gate_type, GateType::MZ ); - let channel = &noisy.get_tick(1).unwrap().gates()[0]; + let channel = &noisy.get_tick(1).unwrap().gate_batches()[0]; assert!(channel.is_channel()); assert_eq!(channel.qubits.as_slice(), &[QubitId::from(0)]); } @@ -5994,13 +5938,13 @@ mod tests { }); assert_eq!(noisy.num_ticks(), 3); - assert_eq!(noisy.get_tick(1).unwrap().gates().len(), 2); - assert_eq!(noisy.get_tick(2).unwrap().gates().len(), 2); + assert_eq!(noisy.get_tick(1).unwrap().gate_batches().len(), 2); + assert_eq!(noisy.get_tick(2).unwrap().gate_batches().len(), 2); assert!( noisy .get_tick(1) .unwrap() - .gates() + .gate_batches() .iter() .all(Gate::is_channel) ); @@ -6008,7 +5952,7 @@ mod tests { noisy .get_tick(2) .unwrap() - .gates() + .gate_batches() .iter() .all(Gate::is_channel) ); diff --git a/docs/user-guide/circuit-representation.md b/docs/user-guide/circuit-representation.md index f871e0547..291ab6d4b 100644 --- a/docs/user-guide/circuit-representation.md +++ b/docs/user-guide/circuit-representation.md @@ -396,6 +396,7 @@ A time-sliced circuit representation where gates are organized into discrete tim print(f"Number of ticks: {circuit.num_ticks()}") print(f"Total gates: {circuit.gate_count()}") + print(f"Gate batches: {circuit.gate_batch_count()}") ``` === ":fontawesome-brands-rust: Rust" @@ -416,6 +417,7 @@ A time-sliced circuit representation where gates are organized into discrete tim println!("Number of ticks: {}", circuit.num_ticks()); println!("Total gates: {}", circuit.gate_count()); + println!("Gate batches: {}", circuit.gate_batch_count()); ``` ### Qubit Conflict Detection @@ -667,8 +669,9 @@ A directed acyclic graph with topological ordering and cycle prevention: | `new()` | Create empty circuit | | `tick()` | Start a new time step | | `num_ticks()` | Number of time steps | -| `gate_count()` | Total gates across all ticks | -| `gate_batch_count()` | Total compatible gate batches across all ticks | +| `gate_count()` | Total gate applications across all ticks | +| `gate_batch_count()` | Total stored compatible gate batches across all ticks | +| `gate_batches()` | Stored gate batches with tick indices | | `set_meta(key, value)` | Circuit-level metadata | ### DAG Methods diff --git a/python/pecos-rslib/src/dag_circuit_bindings.rs b/python/pecos-rslib/src/dag_circuit_bindings.rs index cb7229ad8..77415ee28 100644 --- a/python/pecos-rslib/src/dag_circuit_bindings.rs +++ b/python/pecos-rslib/src/dag_circuit_bindings.rs @@ -2055,11 +2055,21 @@ pub struct PyTick { #[pymethods] impl PyTick { - /// Get the number of gates in this tick. + /// Get the number of stored gate batches in this tick. fn __len__(&self) -> usize { self.inner.len() } + /// Get the number of individual gate applications in this tick. + fn gate_count(&self) -> usize { + self.inner.gate_count() + } + + /// Get the number of compatible gate batches in this tick. + fn gate_batch_count(&self) -> usize { + self.inner.gate_batch_count() + } + /// Check if the tick is empty. fn is_empty(&self) -> bool { self.inner.is_empty() @@ -2228,6 +2238,11 @@ impl PyTickCircuit { self.inner.gate_count() } + /// Get the total number of compatible gate batches across all ticks. + fn gate_batch_count(&self) -> usize { + self.inner.gate_batch_count() + } + /// Get the total number of measurement results produced so far. fn num_measurements(&self) -> usize { self.inner.num_measurements() diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_circuit_representation.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_circuit_representation.rs index 92d8e980f..4862d6ab2 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_circuit_representation.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_circuit_representation.rs @@ -163,6 +163,7 @@ circuit.tick().mz(&[0, 1]); println!("Number of ticks: {}", circuit.num_ticks()); println!("Total gates: {}", circuit.gate_count()); +println!("Gate batches: {}", circuit.gate_batch_count()); } diff --git a/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py b/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py index 47f4079a0..c141c4694 100644 --- a/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py +++ b/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py @@ -1003,6 +1003,20 @@ def test_brickwork_d5(self, width, seed): class TestTickCircuitStructure: + def test_gate_count_and_gate_batch_count_are_distinct(self): + tc = TickCircuit() + tc.tick().h([0]).h([1]).cx([(2, 3), (4, 5)]) + + tick = tc.get_tick(0) + assert tick.gate_count() == 4 + assert tick.gate_batch_count() == 2 + assert len(tick.gate_batches()) == 2 + assert len(tick) == 2 + + assert tc.gate_count() == 4 + assert tc.gate_batch_count() == 2 + assert len(tc.gate_batches()) == 2 + @pytest.mark.parametrize("num_qubits", [1, 2, 3, 5, 8]) @pytest.mark.parametrize("depth", [10, 30]) @pytest.mark.parametrize("seed", range(3)) From bffc53863f3f14c3350a22b862f81e70cc772180 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 14:05:23 -0600 Subject: [PATCH 110/125] Simplify Tick storage and update stubs --- crates/pecos-quantum/src/tick_circuit.rs | 63 ++---- python/pecos-rslib/pecos_rslib.pyi | 277 +++++++++++++++++++++++ 2 files changed, 294 insertions(+), 46 deletions(-) diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index 3d433b056..bfd5e75d4 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -64,8 +64,7 @@ use pecos_core::gate_type::GateType; use pecos_core::{ - Angle64, ChannelExpr, Gate, GateAngles, GateMeasIds, GateParams, GateQubits, GateSignature, - MeasId, QubitId, TimeUnits, + Angle64, ChannelExpr, Gate, GateMeasIds, GateQubits, GateSignature, MeasId, QubitId, TimeUnits, }; use std::collections::{BTreeMap, BTreeSet}; @@ -329,81 +328,53 @@ impl From for CustomGateError { #[derive(Debug, Clone, Default)] struct TickGateStorage { - gate_types: Vec, - angles: Vec, - params: Vec, - qubits: Vec, - meas_ids: Vec, - channels: Vec>, - materialized: Vec, + commands: Vec, } impl TickGateStorage { fn len(&self) -> usize { - self.gate_types.len() + self.commands.len() } fn is_empty(&self) -> bool { - self.gate_types.is_empty() + self.commands.is_empty() } fn as_slice(&self) -> &[Gate] { - &self.materialized + &self.commands } fn iter(&self) -> std::slice::Iter<'_, Gate> { - self.materialized.iter() + self.commands.iter() } fn get(&self, idx: usize) -> Option<&Gate> { - self.materialized.get(idx) + self.commands.get(idx) } fn push(&mut self, gate: Gate) { - self.gate_types.push(gate.gate_type); - self.angles.push(gate.angles.clone()); - self.params.push(gate.params.clone()); - self.qubits.push(gate.qubits.clone()); - self.meas_ids.push(gate.meas_ids.clone()); - self.channels.push(gate.channel.clone()); - self.materialized.push(gate); + self.commands.push(gate); } fn set(&mut self, idx: usize, gate: Gate) { - self.gate_types[idx] = gate.gate_type; - self.angles[idx].clone_from(&gate.angles); - self.params[idx].clone_from(&gate.params); - self.qubits[idx].clone_from(&gate.qubits); - self.meas_ids[idx].clone_from(&gate.meas_ids); - self.channels[idx].clone_from(&gate.channel); - self.materialized[idx] = gate; + self.commands[idx] = gate; } fn remove(&mut self, idx: usize) -> Gate { - self.gate_types.remove(idx); - self.angles.remove(idx); - self.params.remove(idx); - self.qubits.remove(idx); - self.meas_ids.remove(idx); - self.channels.remove(idx); - self.materialized.remove(idx) + self.commands.remove(idx) } fn append_batch(&mut self, idx: usize, gate: Gate) { assert!( - self.materialized[idx].can_batch_with(&gate), + self.commands[idx].can_batch_with(&gate), "cannot merge incompatible gate batches" ); - self.qubits[idx].extend(gate.qubits.iter().copied()); - self.meas_ids[idx].extend(gate.meas_ids.iter().copied()); - self.materialized[idx].append_batch(gate); + self.commands[idx].append_batch(gate); } fn truncate_payload(&mut self, idx: usize, qubit_len: usize, meas_id_len: usize) { - self.qubits[idx].truncate(qubit_len); - self.meas_ids[idx].truncate(meas_id_len); - self.materialized[idx].qubits.truncate(qubit_len); - self.materialized[idx].meas_ids.truncate(meas_id_len); + self.commands[idx].qubits.truncate(qubit_len); + self.commands[idx].meas_ids.truncate(meas_id_len); } } @@ -419,7 +390,7 @@ impl Index for TickGateStorage { type Output = Gate; fn index(&self, index: usize) -> &Self::Output { - &self.materialized[index] + &self.commands[index] } } @@ -861,8 +832,8 @@ impl Tick { /// Mutate a stored gate batch through a temporary [`Gate`] value. /// - /// This keeps the internal `SoA` storage synchronized with the materialized - /// compatibility view returned by [`gate_batches`](Self::gate_batches). + /// The updated gate batch is validated with the same conflict checks as a + /// full replacement before it is written back. /// /// # Errors /// diff --git a/python/pecos-rslib/pecos_rslib.pyi b/python/pecos-rslib/pecos_rslib.pyi index 7c6f4e43d..5a2d04aac 100644 --- a/python/pecos-rslib/pecos_rslib.pyi +++ b/python/pecos-rslib/pecos_rslib.pyi @@ -18,6 +18,7 @@ from __future__ import annotations import os from typing import ( + Any, Callable, Generic, Iterator, @@ -1392,6 +1393,282 @@ class llvm: ... +# ============================================================================= +# Tick Circuit +# ============================================================================= + +class GateType: + """Gate type marker.""" + + H: GateType + X: GateType + Y: GateType + Z: GateType + S: GateType + Sdg: GateType + SX: GateType + SXdg: GateType + SY: GateType + SYdg: GateType + T: GateType + Tdg: GateType + I: GateType + CX: GateType + CY: GateType + CZ: GateType + RX: GateType + RY: GateType + RZ: GateType + RXX: GateType + RYY: GateType + RZZ: GateType + R1XY: GateType + U: GateType + F: GateType + Fdg: GateType + SXX: GateType + SXXdg: GateType + SYY: GateType + SYYdg: GateType + SZZ: GateType + SZZdg: GateType + SWAP: GateType + CH: GateType + CRZ: GateType + CCX: GateType + Measure: GateType + MeasureFree: GateType + Prep: GateType + QAlloc: GateType + QFree: GateType + Custom: GateType + + @property + def name(self) -> str: ... + +class Gate: + """Quantum gate or stored TickCircuit gate batch.""" + + def __init__( + self, + gate_type: GateType, + params: Sequence[float] | None = None, + qubits: Sequence[int] | None = None, + ) -> None: ... + @property + def gate_type(self) -> GateType: ... + @property + def qubits(self) -> list[int]: ... + @property + def params(self) -> list[float]: ... + @property + def angles(self) -> list[float]: ... + @property + def meas_ids(self) -> list[int]: ... + def is_single_qubit(self) -> bool: ... + def is_two_qubit(self) -> bool: ... + def is_channel(self) -> bool: ... + def channel_mixed_pauli_terms(self) -> list[Any]: ... + @staticmethod + def h(qubits: Sequence[int]) -> Gate: ... + @staticmethod + def x(qubits: Sequence[int]) -> Gate: ... + @staticmethod + def y(qubits: Sequence[int]) -> Gate: ... + @staticmethod + def z(qubits: Sequence[int]) -> Gate: ... + @staticmethod + def cx(pairs: Sequence[tuple[int, int]]) -> Gate: ... + @staticmethod + def cy(pairs: Sequence[tuple[int, int]]) -> Gate: ... + @staticmethod + def cz(pairs: Sequence[tuple[int, int]]) -> Gate: ... + @staticmethod + def mz(qubits: Sequence[int]) -> Gate: ... + @staticmethod + def pz(qubits: Sequence[int]) -> Gate: ... + +class DagCircuit: + """Directed acyclic graph circuit representation.""" + + def __init__(self) -> None: ... + def gate_count(self) -> int: ... + def gate(self, node: int) -> Gate | None: ... + def nodes(self) -> list[int]: ... + def to_tick_circuit(self) -> TickCircuit: ... + +class Tick: + """A single time slice of a tick-based quantum circuit.""" + + def __len__(self) -> int: ... + def gate_count(self) -> int: + """Number of individual gate applications in this tick.""" + ... + def gate_batch_count(self) -> int: + """Number of stored compatible gate batches in this tick.""" + ... + def is_empty(self) -> bool: ... + def gate_batches(self) -> list[Gate]: ... + def get_gate_attr(self, gate_idx: int, key: str) -> Any | None: ... + def set_gate_attr(self, gate_idx: int, key: str, value: Any) -> None: ... + def set_gate_attrs(self, gate_idx: int, attrs: Mapping[str, Any]) -> None: ... + def get_attr(self, key: str) -> Any | None: ... + def meta(self, key: str, value: Any) -> None: ... + def metas(self, attrs: Mapping[str, Any]) -> None: ... + def active_qubits(self) -> list[int]: ... + def uses_qubit(self, qubit: int) -> bool: ... + def find_conflicts(self, qubits: Sequence[int]) -> list[Any]: ... + def add_gate(self, gate: Gate) -> int: ... + def try_add_gate(self, gate: Gate) -> int: ... + def discard(self, qubits: Sequence[int]) -> int: ... + def remove_gate(self, idx: int) -> Gate | None: ... + +class TickHandle: + """Handle for adding gates to a tick.""" + + def index(self) -> int: ... + def meta(self, key: str, value: Any) -> TickHandle: ... + def metas(self, attrs: Mapping[str, Any]) -> TickHandle: ... + def h(self, qubits: Sequence[int]) -> TickHandle: ... + def x(self, qubits: Sequence[int]) -> TickHandle: ... + def y(self, qubits: Sequence[int]) -> TickHandle: ... + def z(self, qubits: Sequence[int]) -> TickHandle: ... + def i(self, qubits: Sequence[int]) -> TickHandle: ... + def sx(self, qubits: Sequence[int]) -> TickHandle: ... + def sxdg(self, qubits: Sequence[int]) -> TickHandle: ... + def sy(self, qubits: Sequence[int]) -> TickHandle: ... + def sydg(self, qubits: Sequence[int]) -> TickHandle: ... + def sz(self, qubits: Sequence[int]) -> TickHandle: ... + def szdg(self, qubits: Sequence[int]) -> TickHandle: ... + def t(self, qubits: Sequence[int]) -> TickHandle: ... + def tdg(self, qubits: Sequence[int]) -> TickHandle: ... + def rx(self, theta: Any, qubits: Sequence[int]) -> TickHandle: ... + def ry(self, theta: Any, qubits: Sequence[int]) -> TickHandle: ... + def rz(self, theta: Any, qubits: Sequence[int]) -> TickHandle: ... + def r1xy(self, theta: Any, phi: Any, qubits: Sequence[int]) -> TickHandle: ... + def u(self, theta: Any, phi: Any, lam: Any, qubits: Sequence[int]) -> TickHandle: ... + def cx(self, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def cy(self, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def cz(self, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def szz(self, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def szzdg(self, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def f(self, qubits: Sequence[int]) -> TickHandle: ... + def fdg(self, qubits: Sequence[int]) -> TickHandle: ... + def sxx(self, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def sxxdg(self, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def syy(self, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def syydg(self, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def swap(self, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def ch(self, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def crz(self, theta: Any, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def ccx(self, triples: Sequence[tuple[int, int, int]]) -> TickHandle: ... + def rxx(self, theta: Any, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def ryy(self, theta: Any, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def rzz(self, theta: Any, pairs: Sequence[tuple[int, int]]) -> TickHandle: ... + def add_gate( + self, + name: str, + qubits: Sequence[int], + angles: Sequence[float] | None = None, + ) -> TickHandle: ... + def custom(self, qubits: Sequence[int]) -> TickHandle: ... + def custom_gate( + self, + name: str, + qubits: Sequence[int], + angles: Sequence[float] | None = None, + ) -> TickHandle: ... + def pz(self, qubits: Sequence[int]) -> TickPrepHandle: ... + def mz(self, qubits: Sequence[int]) -> list[tuple[int, int, int]]: ... + def mz_with_ids( + self, + qubits: Sequence[int], + meas_ids: Sequence[int], + ) -> list[tuple[int, int, int]]: ... + def mz_free(self, qubits: Sequence[int]) -> list[tuple[int, int, int]]: ... + def qalloc(self, qubits: Sequence[int]) -> TickHandle: ... + def qfree(self, qubits: Sequence[int]) -> TickHandle: ... + def idle(self, duration: Any, qubits: Sequence[int]) -> TickHandle: ... + +class TickPrepHandle: + """Handle returned by preparation gates for attaching metadata.""" + + def meta(self, key: str, value: Any) -> None: ... + def metas(self, attrs: Mapping[str, Any]) -> None: ... + +class TickMeasureHandle: + """Handle returned by measurement gates for attaching metadata.""" + + def meta(self, key: str, value: Any) -> None: ... + def metas(self, attrs: Mapping[str, Any]) -> None: ... + +class TickCircuit: + """Tick-based quantum circuit representation.""" + + def __init__(self) -> None: ... + def tick(self) -> TickHandle: + """Add a new tick and return a handle for adding gates.""" + ... + def num_ticks(self) -> int: ... + def gate_count(self) -> int: + """Total number of individual gate applications.""" + ... + def gate_batch_count(self) -> int: + """Total number of stored compatible gate batches.""" + ... + def num_measurements(self) -> int: ... + def next_tick_index(self) -> int: ... + def get_tick(self, idx: int) -> Tick | None: ... + def tick_at(self, idx: int) -> TickHandle: ... + def insert_tick(self, idx: int) -> TickHandle: ... + def gate_batches(self) -> list[tuple[int, Gate]]: ... + def all_qubits(self) -> list[int]: ... + def gate_counts_by_type(self) -> dict[str, int]: ... + def set_meta(self, key: str, value: Any) -> None: ... + def metas(self, attrs: Mapping[str, Any]) -> None: ... + def get_meta(self, key: str) -> Any | None: ... + def add_detector( + self, + records: Sequence[int], + coords: Sequence[float] | None = None, + label: str | None = None, + detector_id: int | None = None, + ) -> int: ... + def add_observable( + self, + records: Sequence[int], + observable_id: int | None = None, + label: str | None = None, + ) -> int: ... + def annotations(self) -> list[Any]: ... + def detector(self, measurements: Any, label: str | None = None) -> int: ... + def observable(self, measurements: Any, label: str | None = None) -> int: ... + def tracked_operator(self, pauli: PauliString, label: str | None = None) -> int: ... + def clear(self) -> None: ... + def reset(self) -> None: ... + def reserve_ticks(self, n: int) -> None: ... + def discard(self, qubits: Sequence[int], tick_idx: int) -> int | None: ... + def set_tick_meta(self, tick_idx: int, key: str, value: Any) -> None: ... + def get_tick_meta(self, tick_idx: int, key: str) -> Any | None: ... + def set_gate_meta(self, tick_idx: int, gate_idx: int, key: str, value: Any) -> None: ... + def get_gate_meta(self, tick_idx: int, gate_idx: int, key: str) -> Any | None: ... + def lower_clifford_rotations(self) -> None: ... + def assign_missing_meas_ids(self) -> None: ... + def insert_idle_after_two_qubit_gates(self, duration: float = 1.0) -> None: ... + def fill_idle_gates(self) -> None: ... + def with_noise( + self, + p1: float = 0.0, + p2: float = 0.0, + p_meas: float = 0.0, + p_prep: float = 0.0, + ) -> TickCircuit: ... + def compact_ticks(self) -> None: ... + def import_gate_signatures(self, sigs: Mapping[str, tuple[int, int]]) -> None: ... + def gate_signatures(self) -> dict[str, tuple[int, int]]: ... + def import_registry(self, registry: Any) -> None: ... + def to_dag_circuit(self) -> DagCircuit: ... + # ============================================================================= # Namespace Modules # ============================================================================= From 09d805c0416247464c22fb5c634bc9cee3929a39 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 14:49:54 -0600 Subject: [PATCH 111/125] Use TickCircuit tick iterators in consumers --- crates/pecos-qec/src/fault_tolerance/fault_sampler.rs | 6 +++--- crates/pecos-qec/src/fault_tolerance/gadget_checker.rs | 2 +- crates/pecos-quantum/src/pass.rs | 8 ++++---- crates/pecos-quantum/src/tick_circuit.rs | 4 ++-- 4 files changed, 10 insertions(+), 10 deletions(-) diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index a7a3e9167..0835aa8a8 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -230,7 +230,7 @@ pub fn build_fault_table( /// Validate that all gates in the `TickCircuit` are supported (before flattening). fn validate_tick_circuit(tc: &TickCircuit) -> Result<(), UnsupportedGateError> { - for (tick_idx, tick) in tc.ticks().iter().enumerate() { + for (tick_idx, tick) in tc.iter_ticks() { for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { if is_standard_1q_clifford_gate(gate.gate_type) || is_standard_2q_clifford_gate(gate.gate_type) @@ -261,7 +261,7 @@ pub(crate) fn flatten_tick_circuit(tc: &TickCircuit) -> (Vec, HashMap = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); let is_mz = is_supported_measurement_gate(gate.gate_type); @@ -1522,7 +1522,7 @@ pub fn symbolic_measurement_history( let mut sim = SymbolicSparseStab::new(num_qubits); - for (tick_idx, tick) in tc.ticks().iter().enumerate() { + for (tick_idx, tick) in tc.iter_ticks() { for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { let qs: Vec = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); diff --git a/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs b/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs index c9ea58d21..e89e6dda5 100644 --- a/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs +++ b/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs @@ -1719,7 +1719,7 @@ impl<'a> GadgetChecker<'a> { } // Propagate through circuit up to max_tick, injecting faults as we go - for (tick_idx, tick) in self.circuit.ticks().iter().enumerate() { + for (tick_idx, tick) in self.circuit.iter_ticks() { if tick_idx > max_tick { break; } diff --git a/crates/pecos-quantum/src/pass.rs b/crates/pecos-quantum/src/pass.rs index 1ffc86df1..18a7ea49b 100644 --- a/crates/pecos-quantum/src/pass.rs +++ b/crates/pecos-quantum/src/pass.rs @@ -667,7 +667,7 @@ impl CircuitPass for CancelInverses { let mut stacks: HashMap> = HashMap::new(); let mut to_remove: Vec<(usize, usize)> = Vec::new(); - for (ti, tick) in circuit.ticks().iter().enumerate() { + for (ti, tick) in circuit.iter_ticks() { for (gi, gate) in tick.gate_batches().iter().enumerate() { let qubits: Vec = gate.qubits.iter().copied().collect(); @@ -750,7 +750,7 @@ impl CircuitPass for MergeAdjacentRotations { let mut angle_adjustments: HashMap<(usize, usize), Angle64> = HashMap::new(); let mut to_remove: Vec<(usize, usize)> = Vec::new(); - for (ti, tick) in circuit.ticks().iter().enumerate() { + for (ti, tick) in circuit.iter_ticks() { for (gi, gate) in tick.gate_batches().iter().enumerate() { let qubits: Vec = gate.qubits.iter().copied().collect(); @@ -858,7 +858,7 @@ impl CircuitPass for PeepholeOptimize { // Build per-qubit timeline: Vec of (tick_idx, gate_idx) in order. let mut timelines: HashMap> = HashMap::new(); - for (ti, tick) in circuit.ticks().iter().enumerate() { + for (ti, tick) in circuit.iter_ticks() { for (gi, gate) in tick.gate_batches().iter().enumerate() { for &q in &gate.qubits { timelines.entry(q).or_default().push((ti, gi)); @@ -1053,7 +1053,7 @@ impl CircuitPass for AbsorbBasisGates { // Forward scan: absorb Z-diagonal gates after Z-preps. let mut z_eigenstate: HashSet = HashSet::new(); - for (ti, tick) in circuit.ticks().iter().enumerate() { + for (ti, tick) in circuit.iter_ticks() { for (gi, gate) in tick.gate_batches().iter().enumerate() { if is_z_prep(gate.gate_type) { for &q in &gate.qubits { diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index bfd5e75d4..70ae399c0 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -3049,7 +3049,7 @@ impl From<&TickCircuit> for DagCircuit { let mut meas_record_to_node: BTreeMap = BTreeMap::new(); let mut meas_record_idx = 0usize; - for (tick_idx, tick) in tc.ticks().iter().enumerate() { + for (tick_idx, tick) in tc.iter_ticks() { for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { // Split batched gates into individual operations. // @@ -4189,7 +4189,7 @@ mod tests { #[test] fn test_small_pseudorandom_tick_dag_round_trip_invariants() { fn assert_no_tick_overlaps(circuit: &TickCircuit) { - for (tick_idx, tick) in circuit.ticks().iter().enumerate() { + for (tick_idx, tick) in circuit.iter_ticks() { let mut active = BTreeSet::new(); for gate in tick.gate_batches() { gate.validate() From 4399ff1a2a386521cca6f57b6215959f5885ffa0 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 15:34:27 -0600 Subject: [PATCH 112/125] Align TickCircuit batch metadata storage --- crates/pecos-quantum/src/tick_circuit.rs | 175 ++++++++++++++++++----- 1 file changed, 137 insertions(+), 38 deletions(-) diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index 70ae399c0..0de41a95d 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -400,7 +400,7 @@ pub struct Tick { /// Gate batches in this tick (all act on disjoint qubits). gate_batches: TickGateStorage, /// Metadata for each gate batch, indexed by position in `gate_batches`. - gate_attrs: BTreeMap>, + batch_attrs: Vec>>, /// Tick-level metadata. attrs: BTreeMap, } @@ -465,8 +465,8 @@ impl Tick { /// Get the full-fidelity gate batches in this tick. /// /// In `TickCircuit`, a stored [`Gate`] command may represent one or more - /// gate applications on disjoint qubits. For example, - /// `cx(&[(0, 1), (2, 3)])` is one batch and two gate applications. + /// individual gates on disjoint qubits. For example, + /// `cx(&[(0, 1), (2, 3)])` is one batch containing two gates. /// /// The batches preserve the complete [`Gate`] payload, including /// measurement IDs and typed channel payloads. @@ -490,6 +490,7 @@ impl Tick { fn push_gate_unchecked(&mut self, gate: Gate) -> usize { let idx = self.gate_batches.len(); self.gate_batches.push(gate); + self.batch_attrs.push(None); idx } @@ -507,8 +508,9 @@ impl Tick { } fn normalized_gate_attrs(&self, gate_idx: usize) -> Option<&BTreeMap> { - self.gate_attrs - .get(&gate_idx) + self.batch_attrs + .get(gate_idx) + .and_then(Option::as_ref) .filter(|attrs| !attrs.is_empty()) } @@ -608,8 +610,8 @@ impl Tick { .truncate_payload(piece.gate_idx, piece.qubit_start, piece.meas_id_start); let split_idx = self.push_gate_unchecked(split_gate); - if let Some(attrs) = self.gate_attrs.get(&piece.gate_idx).cloned() { - self.gate_attrs.insert(split_idx, attrs); + if let Some(attrs) = self.normalized_gate_attrs(piece.gate_idx).cloned() { + self.batch_attrs[split_idx] = Some(attrs); } split_idx } @@ -639,9 +641,12 @@ impl Tick { /// /// Returns the gate index. pub fn set_gate_attr(&mut self, gate_idx: usize, key: &str, value: Attribute) -> usize { - self.gate_attrs - .entry(gate_idx) - .or_default() + assert!( + gate_idx < self.gate_batches.len(), + "gate index {gate_idx} out of bounds" + ); + self.batch_attrs[gate_idx] + .get_or_insert_with(BTreeMap::new) .insert(key.to_string(), value); gate_idx } @@ -650,14 +655,25 @@ impl Tick { /// /// Returns the gate index. pub fn set_gate_attrs(&mut self, gate_idx: usize, attrs: BTreeMap) -> usize { - self.gate_attrs.entry(gate_idx).or_default().extend(attrs); + assert!( + gate_idx < self.gate_batches.len(), + "gate index {gate_idx} out of bounds" + ); + if !attrs.is_empty() { + self.batch_attrs[gate_idx] + .get_or_insert_with(BTreeMap::new) + .extend(attrs); + } gate_idx } /// Get metadata from a gate. #[must_use] pub fn get_gate_attr(&self, gate_idx: usize, key: &str) -> Option<&Attribute> { - self.gate_attrs.get(&gate_idx).and_then(|m| m.get(key)) + self.batch_attrs + .get(gate_idx) + .and_then(Option::as_ref) + .and_then(|m| m.get(key)) } /// Set tick-level metadata. @@ -678,8 +694,9 @@ impl Tick { /// Get all attributes for a gate. pub fn gate_attrs(&self, gate_idx: usize) -> impl Iterator { - self.gate_attrs - .get(&gate_idx) + self.batch_attrs + .get(gate_idx) + .and_then(Option::as_ref) .into_iter() .flat_map(|m| m.iter()) } @@ -892,17 +909,7 @@ impl Tick { // Remove gates in reverse order to preserve indices for &idx in indices_to_remove.iter().rev() { - self.gate_batches.remove(idx); - } - - // Rebuild gate_attrs with updated indices - let old_attrs = std::mem::take(&mut self.gate_attrs); - for (old_idx, attrs) in old_attrs { - // Count how many removed indices are before this one - let shift = indices_to_remove.iter().filter(|&&i| i < old_idx).count(); - if !indices_to_remove.contains(&old_idx) { - self.gate_attrs.insert(old_idx - shift, attrs); - } + let _ = self.remove_gate(idx); } removed_count @@ -932,17 +939,7 @@ impl Tick { } let gate = self.gate_batches.remove(idx); - - // Rebuild gate_attrs with updated indices - let old_attrs = std::mem::take(&mut self.gate_attrs); - for (old_idx, attrs) in old_attrs { - if old_idx < idx { - self.gate_attrs.insert(old_idx, attrs); - } else if old_idx > idx { - self.gate_attrs.insert(old_idx - 1, attrs); - } - // Skip old_idx == idx (removed gate's attrs) - } + self.batch_attrs.remove(idx); Some(gate) } @@ -1783,7 +1780,7 @@ impl TickCircuit { /// Iterate over full-fidelity gate batches in the circuit. /// /// This is the preferred API for consumers that execute or analyze batched - /// commands. Each yielded [`Gate`] may represent multiple gate applications + /// commands. Each yielded [`Gate`] may represent multiple individual gates /// on disjoint qubits, and carries the full gate payload. pub fn iter_gate_batches(&self) -> impl Iterator { self.ticks.iter().flat_map(Tick::gate_batches) @@ -2106,7 +2103,7 @@ impl TickCircuit { if all_clear { // Move gates and their per-gate metadata into the target tick. for (gi, gate) in tick.gate_batches.iter().enumerate() { - if let Some(attrs) = tick.gate_attrs.get(&gi) { + if let Some(attrs) = tick.normalized_gate_attrs(gi) { let new_idx = compacted[target_idx] .try_add_gate_preserving_command(gate.clone()) .unwrap_or_else(|err| panic!("{err}")); @@ -3296,6 +3293,25 @@ mod tests { ); } + #[test] + fn test_tick_replace_gate_batch_preserves_aligned_attrs() { + let mut tc = TickCircuit::new(); + tc.tick() + .h(&[0, 1]) + .meta("calibration", Attribute::String("old".into())); + + let tick = tc.get_tick_mut(0).unwrap(); + tick.replace_gate_batch(0, Gate::x(&[0, 1])) + .expect("same support replacement should be valid"); + + assert_eq!(tick.len(), 1); + assert_eq!(tick.gate_batches()[0].gate_type, GateType::X); + assert_eq!( + tick.get_gate_attr(0, "calibration"), + Some(&Attribute::String("old".into())) + ); + } + #[test] fn test_tick_replace_gate_batch_rejects_overlapping_qubits() { let mut tc = TickCircuit::new(); @@ -5351,6 +5367,35 @@ mod tests { assert!(tick.get_gate_attr(1, "x_attr").is_none()); } + #[test] + fn test_tick_remove_gate_preserves_aligned_attrs() { + let mut tc = TickCircuit::new(); + tc.tick() + .h(&[0]) + .meta("h_attr", Attribute::Int(1)) + .x(&[1]) + .meta("x_attr", Attribute::Int(2)) + .z(&[2]) + .meta("z_attr", Attribute::Int(3)); + + let tick = tc.get_tick_mut(0).unwrap(); + let removed = tick.remove_gate(0).expect("H batch should exist"); + + assert_eq!(removed.gate_type, GateType::H); + assert_eq!(tick.len(), 2); + assert_eq!(tick.gate_batches()[0].gate_type, GateType::X); + assert_eq!(tick.gate_batches()[1].gate_type, GateType::Z); + assert_eq!( + tick.get_gate_attr(0, "x_attr"), + Some(&Attribute::Int(2)) + ); + assert_eq!( + tick.get_gate_attr(1, "z_attr"), + Some(&Attribute::Int(3)) + ); + assert!(tick.get_gate_attr(0, "h_attr").is_none()); + } + #[test] fn test_tick_remove_gate() { let mut tc = TickCircuit::new(); @@ -5380,6 +5425,60 @@ mod tests { assert_eq!(tick.len(), 1); } + #[test] + fn test_compact_ticks_preserves_and_merges_aligned_batch_attrs() { + let mut tc = TickCircuit::new(); + tc.tick() + .h(&[0]) + .meta("calibration", Attribute::String("shared".into())); + tc.tick() + .h(&[1]) + .meta("calibration", Attribute::String("shared".into())); + + tc.compact_ticks(); + + assert_eq!(tc.num_ticks(), 1); + let tick = tc.get_tick(0).unwrap(); + assert_eq!(tick.len(), 1); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 1); + assert_eq!( + tick.gate_batches()[0].qubits.as_slice(), + &[QubitId::from(0), QubitId::from(1)] + ); + assert_eq!( + tick.get_gate_attr(0, "calibration"), + Some(&Attribute::String("shared".into())) + ); + } + + #[test] + fn test_compact_ticks_keeps_different_batch_attrs_separate() { + let mut tc = TickCircuit::new(); + tc.tick() + .h(&[0]) + .meta("calibration", Attribute::String("a".into())); + tc.tick() + .h(&[1]) + .meta("calibration", Attribute::String("b".into())); + + tc.compact_ticks(); + + assert_eq!(tc.num_ticks(), 1); + let tick = tc.get_tick(0).unwrap(); + assert_eq!(tick.len(), 2); + assert_eq!(tick.gate_count(), 2); + assert_eq!(tick.gate_batch_count(), 2); + assert_eq!( + tick.get_gate_attr(0, "calibration"), + Some(&Attribute::String("a".into())) + ); + assert_eq!( + tick.get_gate_attr(1, "calibration"), + Some(&Attribute::String("b".into())) + ); + } + #[test] fn test_circuit_discard() { let mut tc = TickCircuit::new(); From 540b2501459591cc1557f85c9bf9fc9ecd224bfa Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 15:48:21 -0600 Subject: [PATCH 113/125] Add TickCircuit borrowed gate views --- crates/pecos-quantum/src/tick_circuit.rs | 282 +++++++++++++++++- exp/pecos-eeg/src/builder.rs | 12 +- .../pecos-rslib/src/dag_circuit_bindings.rs | 2 +- 3 files changed, 283 insertions(+), 13 deletions(-) diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index 0de41a95d..850c72c8c 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -414,6 +414,185 @@ struct GateBatchPiece { meas_id_len: usize, } +/// Borrowed view of one stored same-type gate batch in a [`Tick`]. +#[derive(Debug, Clone, Copy)] +pub struct GateBatchRef<'a> { + batch_index: usize, + gate: &'a Gate, + attrs: Option<&'a BTreeMap>, +} + +impl<'a> GateBatchRef<'a> { + fn new( + batch_index: usize, + gate: &'a Gate, + attrs: Option<&'a BTreeMap>, + ) -> Self { + Self { + batch_index, + gate, + attrs, + } + } + + /// Return this batch's index within its tick. + #[must_use] + pub fn batch_index(self) -> usize { + self.batch_index + } + + /// Return the underlying stored [`Gate`] batch. + #[must_use] + pub fn as_gate(self) -> &'a Gate { + self.gate + } + + /// Return the number of individual gates represented by this batch. + #[must_use] + pub fn gate_count(self) -> usize { + self.gate.num_gates() + } + + /// Return the metadata attribute with the given key, if present. + #[must_use] + pub fn get_attr(self, key: &str) -> Option<&'a Attribute> { + self.attrs.and_then(|attrs| attrs.get(key)) + } + + /// Iterate over metadata attributes attached to this batch. + pub fn attrs(self) -> impl Iterator { + self.attrs.into_iter().flat_map(|attrs| attrs.iter()) + } + + /// Return one individual gate from this batch. + #[must_use] + pub fn instance(self, instance_index: usize) -> Option> { + let gate_count = self.gate_count(); + if instance_index >= gate_count { + return None; + } + + let qubits = if gate_count == 1 { + self.gate.qubits.as_slice() + } else { + let arity = self.gate.quantum_arity(); + let start = instance_index * arity; + let end = start + arity; + self.gate.qubits.get(start..end)? + }; + + let meas_ids = if self.gate.meas_ids.is_empty() { + &self.gate.meas_ids[0..0] + } else if gate_count == 1 { + self.gate.meas_ids.as_slice() + } else { + if !self.gate.meas_ids.len().is_multiple_of(gate_count) { + return None; + } + let arity = self.gate.meas_ids.len() / gate_count; + let start = instance_index * arity; + let end = start + arity; + self.gate.meas_ids.get(start..end)? + }; + + Some(GateInstanceRef { + batch: self, + instance_index, + qubits, + meas_ids, + }) + } + + /// Iterate over individual gates represented by this batch. + pub fn iter_gate_instances(self) -> impl Iterator> { + (0..self.gate_count()).filter_map(move |idx| self.instance(idx)) + } +} + +impl Deref for GateBatchRef<'_> { + type Target = Gate; + + fn deref(&self) -> &Self::Target { + self.gate + } +} + +/// Borrowed view of one individual gate inside a [`GateBatchRef`]. +#[derive(Debug, Clone, Copy)] +pub struct GateInstanceRef<'a> { + batch: GateBatchRef<'a>, + instance_index: usize, + qubits: &'a [QubitId], + meas_ids: &'a [MeasId], +} + +impl<'a> GateInstanceRef<'a> { + /// Return the stored batch this individual gate came from. + #[must_use] + pub fn batch(self) -> GateBatchRef<'a> { + self.batch + } + + /// Return the parent batch's index within its tick. + #[must_use] + pub fn batch_index(self) -> usize { + self.batch.batch_index() + } + + /// Return this gate's position within its stored batch. + #[must_use] + pub fn instance_index(self) -> usize { + self.instance_index + } + + /// Return this individual gate's type. + #[must_use] + pub fn gate_type(self) -> GateType { + self.batch.gate_type + } + + /// Return this individual gate's qubit support. + #[must_use] + pub fn qubits(self) -> &'a [QubitId] { + self.qubits + } + + /// Return this individual gate's measurement ids, if any. + #[must_use] + pub fn meas_ids(self) -> &'a [MeasId] { + self.meas_ids + } + + /// Return this individual gate's rotation angles. + #[must_use] + pub fn angles(self) -> &'a [Angle64] { + self.batch.gate.angles.as_slice() + } + + /// Return this individual gate's non-angle parameters. + #[must_use] + pub fn params(self) -> &'a [f64] { + self.batch.gate.params.as_slice() + } + + /// Return this individual gate's channel payload, if this is a channel. + #[must_use] + pub fn channel(self) -> Option<&'a ChannelExpr> { + self.batch.gate.channel.as_ref() + } + + /// Return the metadata attribute with the given key, if present. + #[must_use] + pub fn get_attr(self, key: &str) -> Option<&'a Attribute> { + self.batch.get_attr(key) + } + + /// Iterate over metadata attributes attached to the parent batch. + pub fn attrs(self) -> impl Iterator { + self.batch.attrs() + } +} + impl Tick { /// Create a new empty tick. #[must_use] @@ -475,6 +654,19 @@ impl Tick { self.gate_batches.as_slice() } + /// Iterate over full-fidelity borrowed gate-batch views in this tick. + pub fn iter_gate_batches(&self) -> impl Iterator> { + self.gate_batches.iter().enumerate().map(|(idx, gate)| { + GateBatchRef::new(idx, gate, self.normalized_gate_attrs(idx)) + }) + } + + /// Iterate over individual gates expanded from this tick's stored batches. + pub fn iter_gate_instances(&self) -> impl Iterator> { + self.iter_gate_batches() + .flat_map(GateBatchRef::iter_gate_instances) + } + /// Add a gate to this tick. /// /// # Panics @@ -1782,20 +1974,34 @@ impl TickCircuit { /// This is the preferred API for consumers that execute or analyze batched /// commands. Each yielded [`Gate`] may represent multiple individual gates /// on disjoint qubits, and carries the full gate payload. - pub fn iter_gate_batches(&self) -> impl Iterator { - self.ticks.iter().flat_map(Tick::gate_batches) + pub fn iter_gate_batches(&self) -> impl Iterator> { + self.ticks.iter().flat_map(Tick::iter_gate_batches) } /// Returns true if any tick contains an explicit channel operation. #[must_use] pub fn has_channel_operations(&self) -> bool { - self.iter_gate_batches().any(Gate::is_channel) + self.iter_gate_batches().any(|gate| gate.is_channel()) } /// Iterate over full-fidelity gate batches with their tick index. - pub fn iter_gate_batches_with_tick(&self) -> impl Iterator { + pub fn iter_gate_batches_with_tick(&self) -> impl Iterator)> { self.ticks.iter().enumerate().flat_map(|(tick_idx, tick)| { - tick.gate_batches().iter().map(move |gate| (tick_idx, gate)) + tick.iter_gate_batches().map(move |gate| (tick_idx, gate)) + }) + } + + /// Iterate over individual gates expanded from stored batches. + pub fn iter_gate_instances(&self) -> impl Iterator> { + self.ticks.iter().flat_map(Tick::iter_gate_instances) + } + + /// Iterate over individual gates with their tick index. + pub fn iter_gate_instances_with_tick( + &self, + ) -> impl Iterator)> { + self.ticks.iter().enumerate().flat_map(|(tick_idx, tick)| { + tick.iter_gate_instances().map(move |gate| (tick_idx, gate)) }) } @@ -1843,9 +2049,12 @@ impl TickCircuit { /// /// // Get all H gates /// let h_gates: Vec<_> = circuit.iter_gates_by_type(GateType::H).collect(); - /// assert_eq!(h_gates.len(), 1); // One Gate object with 3 qubits + /// assert_eq!(h_gates.len(), 1); // One H batch with 3 qubits /// ``` - pub fn iter_gates_by_type(&self, gate_type: GateType) -> impl Iterator { + pub fn iter_gates_by_type( + &self, + gate_type: GateType, + ) -> impl Iterator> { self.iter_gate_batches() .filter(move |g| g.gate_type == gate_type) } @@ -1867,7 +2076,7 @@ impl TickCircuit { #[must_use] pub fn all_qubits(&self) -> BTreeSet { self.iter_gate_batches() - .flat_map(|gate| gate.qubits.iter().copied()) + .flat_map(|gate| gate.as_gate().qubits.iter().copied()) .collect() } @@ -4223,7 +4432,7 @@ mod tests { fn measurement_ids(circuit: &TickCircuit) -> Vec { circuit .iter_gate_batches() - .flat_map(|gate| gate.meas_ids.iter().copied()) + .flat_map(|gate| gate.as_gate().meas_ids.iter().copied()) .collect() } @@ -5031,20 +5240,59 @@ mod tests { #[test] fn test_iteration_helpers() { let mut tc = TickCircuit::new(); - tc.tick().h(&[0, 1, 2, 3]); + tc.tick() + .h(&[0, 1, 2, 3]) + .meta("calibration", Attribute::String("h-cal".into())); tc.tick().cx(&[(0, 1), (2, 3)]); tc.tick().mz(&[0, 1, 2, 3]); // Test explicit batched views. These preserve full Gate payloads. let batches: Vec<_> = tc.iter_gate_batches().collect(); assert_eq!(batches.len(), 3); + assert_eq!(batches[0].batch_index(), 0); assert_eq!(batches[0].gate_type, GateType::H); assert_eq!(batches[0].num_gates(), 4); + assert_eq!(batches[0].gate_count(), 4); + assert_eq!( + batches[0].get_attr("calibration"), + Some(&Attribute::String("h-cal".into())) + ); assert_eq!(tc.get_tick(0).unwrap().gate_batches()[0].num_gates(), 4); let batches_with_tick: Vec<_> = tc.iter_gate_batches_with_tick().collect(); assert_eq!(batches_with_tick.len(), 3); assert_eq!(batches_with_tick[2].0, 2); // Third batch is in tick 2 + assert_eq!(batches_with_tick[2].1.gate_type, GateType::MZ); + + let instances_with_tick: Vec<_> = tc.iter_gate_instances_with_tick().collect(); + assert_eq!(instances_with_tick.len(), 10); + assert_eq!(instances_with_tick[0].0, 0); + assert_eq!(instances_with_tick[0].1.batch_index(), 0); + assert_eq!(instances_with_tick[0].1.instance_index(), 0); + assert_eq!(instances_with_tick[0].1.gate_type(), GateType::H); + assert_eq!(instances_with_tick[0].1.qubits(), &[QubitId::from(0)]); + assert_eq!( + instances_with_tick[0].1.get_attr("calibration"), + Some(&Attribute::String("h-cal".into())) + ); + assert_eq!(instances_with_tick[3].1.qubits(), &[QubitId::from(3)]); + assert_eq!(instances_with_tick[4].0, 1); + assert_eq!(instances_with_tick[4].1.instance_index(), 0); + assert_eq!(instances_with_tick[4].1.gate_type(), GateType::CX); + assert_eq!( + instances_with_tick[4].1.qubits(), + &[QubitId::from(0), QubitId::from(1)] + ); + assert_eq!( + instances_with_tick[5].1.qubits(), + &[QubitId::from(2), QubitId::from(3)] + ); + assert_eq!(instances_with_tick[5].1.instance_index(), 1); + assert_eq!(instances_with_tick[6].0, 2); + assert_eq!(instances_with_tick[6].1.gate_type(), GateType::MZ); + assert_eq!(instances_with_tick[6].1.qubits(), &[QubitId::from(0)]); + assert_eq!(instances_with_tick[6].1.meas_ids(), &[MeasId(0)]); + assert_eq!(instances_with_tick[9].1.meas_ids(), &[MeasId(3)]); // Test iter_ticks let ticks: Vec<_> = tc.iter_ticks().collect(); @@ -5073,6 +5321,20 @@ mod tests { assert_eq!(counts.get(&GateType::MZ), Some(&4)); } + #[test] + fn test_gate_instance_iteration_skips_annotation_batches() { + let mut tick = Tick::new(); + tick.add_gate(Gate::simple( + GateType::PauliOperatorMeta, + vec![QubitId::from(0), QubitId::from(1)], + )); + + let batches: Vec<_> = tick.iter_gate_batches().collect(); + assert_eq!(batches.len(), 1); + assert_eq!(batches[0].gate_count(), 0); + assert_eq!(tick.iter_gate_instances().count(), 0); + } + #[test] fn test_clear() { let mut tc = TickCircuit::new(); diff --git a/exp/pecos-eeg/src/builder.rs b/exp/pecos-eeg/src/builder.rs index 71c89d57e..7faca6a85 100644 --- a/exp/pecos-eeg/src/builder.rs +++ b/exp/pecos-eeg/src/builder.rs @@ -57,7 +57,11 @@ impl<'a> EegDemBuilder<'a> { #[must_use] pub fn build(&self) -> Vec { - let gates: Vec = self.tc.iter_gate_batches().cloned().collect(); + let gates: Vec = self + .tc + .iter_gate_batches() + .map(|batch| batch.as_gate().clone()) + .collect(); let expanded = expand::expand_circuit(&gates); let result = circuit::analyze_expanded(&expanded.gates, &self.noise); let (detectors, observables) = build_detectors(self.tc, &expanded); @@ -85,7 +89,11 @@ impl<'a> EegDemBuilder<'a> { #[must_use] pub fn summary(&self) -> EegSummary { - let gates: Vec = self.tc.iter_gate_batches().cloned().collect(); + let gates: Vec = self + .tc + .iter_gate_batches() + .map(|batch| batch.as_gate().clone()) + .collect(); let expanded = expand::expand_circuit(&gates); let result = circuit::analyze_expanded(&expanded.gates, &self.noise); let (detectors, observables) = build_detectors(self.tc, &expanded); diff --git a/python/pecos-rslib/src/dag_circuit_bindings.rs b/python/pecos-rslib/src/dag_circuit_bindings.rs index 77415ee28..a55a4970a 100644 --- a/python/pecos-rslib/src/dag_circuit_bindings.rs +++ b/python/pecos-rslib/src/dag_circuit_bindings.rs @@ -2447,7 +2447,7 @@ impl PyTickCircuit { ( tick_idx, PyGate { - inner: gate.clone(), + inner: gate.as_gate().clone(), }, ) }) From 4ceae2c2ced59658daafcd53f9efbd92353d1a80 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 16:04:11 -0600 Subject: [PATCH 114/125] Migrate TickCircuit consumers to gate batch views --- .../src/fault_tolerance/circuit_runner.rs | 14 +++--- .../src/fault_tolerance/fault_sampler.rs | 16 +++---- .../src/fault_tolerance/gadget_checker.rs | 4 +- .../src/fault_tolerance/pauli_prop_checker.rs | 24 +++++----- .../src/fault_tolerance/propagator/pauli.rs | 16 +++---- .../src/fault_tolerance/propagator/tick.rs | 12 ++--- crates/pecos-quantum/src/pass.rs | 48 ++++++++++--------- .../pecos-simulators/src/circuit_executor.rs | 4 +- exp/pecos-eeg/src/builder.rs | 5 +- exp/pecos-eeg/tests/surface_code.rs | 10 +++- exp/pecos-neo/src/circuit.rs | 4 +- exp/pecos-neo/src/engines.rs | 4 +- exp/pecos-neo/src/inline_channel.rs | 10 ++-- 13 files changed, 93 insertions(+), 78 deletions(-) diff --git a/crates/pecos-qec/src/fault_tolerance/circuit_runner.rs b/crates/pecos-qec/src/fault_tolerance/circuit_runner.rs index 78491196a..1f16ca073 100644 --- a/crates/pecos-qec/src/fault_tolerance/circuit_runner.rs +++ b/crates/pecos-qec/src/fault_tolerance/circuit_runner.rs @@ -60,7 +60,7 @@ pub fn extract_spacetime_locations( // Iterate through all ticks for (tick_idx, tick) in circuit.iter_ticks() { - for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { + for gate in tick.iter_gate_batches() { let qubits: Vec = gate.qubits.iter().copied().collect(); let is_measurement = matches!(gate.gate_type, GateType::MZ | GateType::MeasureFree); @@ -69,7 +69,7 @@ pub fn extract_spacetime_locations( qubits, is_measurement, // Measurements get "before" errors gate.gate_type, - gate_idx, + gate.batch_index(), )); } } @@ -105,10 +105,10 @@ fn apply_fault(sim: &mut S, fault: &PauliFault) { /// simulator-level batch optimizations (gate fusion, SIMD batching, etc.). fn apply_tick_gates(sim: &mut S, tick: &pecos_quantum::Tick) { // For ticks with few gates, skip consolidation overhead - let gate_count = tick.gate_batches().len(); + let gate_count = tick.len(); if gate_count <= 2 { - for gate in tick.gate_batches() { - apply_gate(sim, gate); + for gate in tick.iter_gate_batches() { + apply_gate(sim, gate.as_gate()); } return; } @@ -139,7 +139,7 @@ fn apply_tick_gates(sim: &mut S, tick: &pecos_quantum::Tick let mut mz_qubits: Vec = Vec::new(); let mut pz_qubits: Vec = Vec::new(); - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { match gate.gate_type { GateType::H => h_qubits.extend(gate.qubits.iter()), GateType::X => x_qubits.extend(gate.qubits.iter()), @@ -208,7 +208,7 @@ fn apply_tick_gates(sim: &mut S, tick: &pecos_quantum::Tick GateType::I => {} _ => { // Fallback: apply individually for unsupported gate types - apply_gate(sim, gate); + apply_gate(sim, gate.as_gate()); } } } diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index 0835aa8a8..841550997 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -231,7 +231,7 @@ pub fn build_fault_table( /// Validate that all gates in the `TickCircuit` are supported (before flattening). fn validate_tick_circuit(tc: &TickCircuit) -> Result<(), UnsupportedGateError> { for (tick_idx, tick) in tc.iter_ticks() { - for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { + for gate in tick.iter_gate_batches() { if is_standard_1q_clifford_gate(gate.gate_type) || is_standard_2q_clifford_gate(gate.gate_type) || is_supported_measurement_gate(gate.gate_type) @@ -243,7 +243,7 @@ fn validate_tick_circuit(tc: &TickCircuit) -> Result<(), UnsupportedGateError> { return Err(UnsupportedGateError { gate_type: gate.gate_type, tick: tick_idx, - gate_in_tick: gate_idx, + gate_in_tick: gate.batch_index(), qubits: gate.qubits.iter().map(pecos_core::QubitId::index).collect(), }); } @@ -262,7 +262,8 @@ pub(crate) fn flatten_tick_circuit(tc: &TickCircuit) -> (Vec, HashMap = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); let is_mz = is_supported_measurement_gate(gate.gate_type); let is_2q = is_standard_2q_clifford_gate(gate.gate_type); @@ -1512,10 +1513,8 @@ pub fn symbolic_measurement_history( use pecos_simulators::SymbolicSparseStab; let num_qubits = tc - .ticks() - .iter() - .flat_map(|t| t.gate_batches().iter()) - .flat_map(|g| g.qubits.iter()) + .iter_gate_batches() + .flat_map(|g| g.as_gate().qubits.iter()) .map(|q| q.index() + 1) .max() .unwrap_or(0); @@ -1523,7 +1522,8 @@ pub fn symbolic_measurement_history( let mut sim = SymbolicSparseStab::new(num_qubits); for (tick_idx, tick) in tc.iter_ticks() { - for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { + for gate in tick.iter_gate_batches() { + let gate_idx = gate.batch_index(); let qs: Vec = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); match gate.gate_type { diff --git a/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs b/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs index e89e6dda5..794cf541a 100644 --- a/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs +++ b/crates/pecos-qec/src/fault_tolerance/gadget_checker.rs @@ -963,7 +963,7 @@ impl<'a> GadgetChecker<'a> { /// Propagate a `PauliProp` through the circuit without additional faults. fn propagate_through_circuit(&self, mut prop: PauliProp) -> PauliProp { for tick in self.circuit.ticks() { - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { let qubits: Vec = gate.qubits.to_vec(); match gate.gate_type { @@ -1741,7 +1741,7 @@ impl<'a> GadgetChecker<'a> { } // Apply gates - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { let qubits: Vec = gate.qubits.to_vec(); match gate.gate_type { pecos_core::gate_type::GateType::H => { diff --git a/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs b/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs index c1042d02b..b7cacb7c3 100644 --- a/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs +++ b/crates/pecos-qec/src/fault_tolerance/pauli_prop_checker.rs @@ -76,7 +76,7 @@ pub fn detect_input_qubits(circuit: &TickCircuit) -> Vec { let mut prepared_qubits: HashSet = HashSet::new(); for (_tick_idx, tick) in circuit.iter_ticks() { - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { for &qubit in &gate.qubits { let q = qubit.index(); all_qubits.insert(q); @@ -108,7 +108,7 @@ pub fn detect_ancilla_qubits(circuit: &TickCircuit) -> Vec { let mut prepared_qubits: HashSet = HashSet::new(); for (_tick_idx, tick) in circuit.iter_ticks() { - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { if gate.gate_type == GateType::PZ { for &qubit in &gate.qubits { prepared_qubits.insert(qubit.index()); @@ -142,7 +142,7 @@ pub fn detect_output_qubits(circuit: &TickCircuit) -> Vec { let mut measured_qubits: HashSet = HashSet::new(); for (_tick_idx, tick) in circuit.iter_ticks() { - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { for &qubit in &gate.qubits { let q = qubit.index(); all_qubits.insert(q); @@ -191,7 +191,7 @@ impl CircuitIO { let mut measured_qubits: HashSet = HashSet::new(); for (_tick_idx, tick) in circuit.iter_ticks() { - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { for &qubit in &gate.qubits { let q = qubit.index(); all_qubits.insert(q); @@ -296,8 +296,8 @@ pub fn propagate_fault(circuit: &TickCircuit, fault: &PauliFault) -> PauliProp { } // Apply all gates in this tick - for gate in tick.gate_batches() { - apply_gate(&mut prop, gate, Direction::Forward); + for gate in tick.iter_gate_batches() { + apply_gate(&mut prop, gate.as_gate(), Direction::Forward); } } @@ -335,8 +335,8 @@ pub fn propagate_faults(circuit: &TickCircuit, faults: &FaultConfiguration) -> P // Propagate through the circuit from the minimum tick onward for (tick_idx, tick) in circuit.iter_ticks() { if tick_idx >= min_tick { - for gate in tick.gate_batches() { - apply_gate(&mut prop, gate, Direction::Forward); + for gate in tick.iter_gate_batches() { + apply_gate(&mut prop, gate.as_gate(), Direction::Forward); } } } @@ -1011,7 +1011,7 @@ pub fn extract_measurement_rounds(circuit: &TickCircuit) -> Vec { // Z-basis measurement @@ -1070,7 +1070,7 @@ fn propagate_until_tick(circuit: &TickCircuit, fault: &PauliFault, until_tick: u } // Propagate through all gates in this tick - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { let qubits: Vec = gate.qubits.iter().copied().collect(); match gate.gate_type { GateType::CX if qubits.len() >= 2 => { @@ -2124,8 +2124,8 @@ impl<'a> PauliPropChecker<'a> { // Propagate through circuit for (_tick_idx, tick) in self.circuit.iter_ticks() { - for gate in tick.gate_batches() { - apply_gate(&mut prop, gate, Direction::Forward); + for gate in tick.iter_gate_batches() { + apply_gate(&mut prop, gate.as_gate(), Direction::Forward); } } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/pauli.rs b/crates/pecos-qec/src/fault_tolerance/propagator/pauli.rs index b1aecd0a6..5b5df18d3 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/pauli.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/pauli.rs @@ -264,15 +264,15 @@ pub fn propagate_through_circuit( match direction { Direction::Forward => { for tick in circuit.ticks() { - for gate in tick.gate_batches() { - apply_gate(prop, gate, direction); + for gate in tick.iter_gate_batches() { + apply_gate(prop, gate.as_gate(), direction); } } } Direction::Backward => { for tick in circuit.ticks().iter().rev() { - for gate in tick.gate_batches() { - apply_gate(prop, gate, direction); + for gate in tick.iter_gate_batches() { + apply_gate(prop, gate.as_gate(), direction); } } } @@ -305,16 +305,16 @@ pub fn propagate_tick_range( Direction::Forward => { for tick_idx in start..=end { let tick = &circuit.ticks()[tick_idx]; - for gate in tick.gate_batches() { - apply_gate(prop, gate, direction); + for gate in tick.iter_gate_batches() { + apply_gate(prop, gate.as_gate(), direction); } } } Direction::Backward => { for tick_idx in (start..=end).rev() { let tick = &circuit.ticks()[tick_idx]; - for gate in tick.gate_batches() { - apply_gate(prop, gate, direction); + for gate in tick.iter_gate_batches() { + apply_gate(prop, gate.as_gate(), direction); } } } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs b/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs index 42d5d3b68..3a94fc0bf 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs @@ -64,7 +64,7 @@ impl<'a> TickFaultAnalyzer<'a> { // Find max qubit for active qubit tracking let mut max_qubit = 0; for tick in circuit.ticks() { - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { for qubit in &gate.qubits { max_qubit = max_qubit.max(qubit.index()); } @@ -151,7 +151,7 @@ impl<'a> TickFaultAnalyzer<'a> { let mut measurements = Vec::new(); for (tick_idx, tick) in self.circuit.iter_ticks() { - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { // Currently only Z-basis measurements are supported let basis = match gate.gate_type { GateType::MZ | GateType::MeasureFree => 0, // Z-basis @@ -229,7 +229,7 @@ impl<'a> TickFaultAnalyzer<'a> { // Apply gates at this tick backward - SPARSE: only gates touching active qubits if tick_idx < self.circuit.ticks().len() { let tick = &self.circuit.ticks()[tick_idx]; - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { // Check if this gate touches any active qubit let touches_active = gate.qubits.iter().any(|q| { let idx = q.index(); @@ -238,7 +238,7 @@ impl<'a> TickFaultAnalyzer<'a> { if touches_active { // Apply gate backward - Self::apply_gate_backward(&mut prop, gate); + Self::apply_gate_backward(&mut prop, gate.as_gate()); // Update active qubits based on new Pauli state for q in &gate.qubits { @@ -319,7 +319,7 @@ impl<'a> TickFaultAnalyzer<'a> { // Apply gates backward - SPARSE: only gates touching active qubits let tick = &self.circuit.ticks()[tick_idx]; - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { // Check if this gate touches any active qubit let touches_active = gate.qubits.iter().any(|q| { let idx = q.index(); @@ -328,7 +328,7 @@ impl<'a> TickFaultAnalyzer<'a> { if touches_active { // Apply gate backward - Self::apply_gate_backward(&mut prop, gate); + Self::apply_gate_backward(&mut prop, gate.as_gate()); // Update active qubits based on new Pauli state for q in &gate.qubits { diff --git a/crates/pecos-quantum/src/pass.rs b/crates/pecos-quantum/src/pass.rs index 18a7ea49b..1a7e39028 100644 --- a/crates/pecos-quantum/src/pass.rs +++ b/crates/pecos-quantum/src/pass.rs @@ -235,7 +235,7 @@ impl CircuitPass for InsertIdleAfterTwoQubitGates { for tick in old_ticks { let mut idle_qubits: Vec = Vec::new(); - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { if gate.is_two_qubit() { for q in &gate.qubits { if !idle_qubits.contains(q) { @@ -452,9 +452,10 @@ fn split_batched_tick_commands(circuit: &mut TickCircuit) { new_tick.set_attr(key, value.clone()); } - for (gate_idx, gate) in old_tick.gate_batches().iter().enumerate() { - let attrs: BTreeMap = old_tick - .gate_attrs(gate_idx) + for batch in old_tick.iter_gate_batches() { + let gate = batch.as_gate(); + let attrs: BTreeMap = batch + .attrs() .map(|(key, value)| (key.clone(), value.clone())) .collect(); @@ -509,12 +510,12 @@ impl CircuitPass for SimplifyRotations { // We need to know which gate indices to remove and what to add. let mut decompositions: Vec<(usize, GateType)> = Vec::new(); - for (i, gate) in tick.gate_batches().iter().enumerate() { + for gate in tick.iter_gate_batches() { if gate.angles.len() == 1 && let Some(pauli) = pecos_core::half_turn_decomposition(gate.gate_type, gate.angles[0]) { - decompositions.push((i, pauli)); + decompositions.push((gate.batch_index(), pauli)); } } @@ -668,12 +669,13 @@ impl CircuitPass for CancelInverses { let mut to_remove: Vec<(usize, usize)> = Vec::new(); for (ti, tick) in circuit.iter_ticks() { - for (gi, gate) in tick.gate_batches().iter().enumerate() { + for gate in tick.iter_gate_batches() { + let gi = gate.batch_index(); let qubits: Vec = gate.qubits.iter().copied().collect(); if let Some((pred_ti, pred_gi)) = check_all_stacks_agree(&stacks, &qubits) { let pred_gate = &circuit.ticks()[pred_ti].gate_batches()[pred_gi]; - if are_inverses(pred_gate, gate) { + if are_inverses(pred_gate, gate.as_gate()) { for &q in &qubits { if let Some(stack) = stacks.get_mut(&q) { stack.pop(); @@ -751,7 +753,8 @@ impl CircuitPass for MergeAdjacentRotations { let mut to_remove: Vec<(usize, usize)> = Vec::new(); for (ti, tick) in circuit.iter_ticks() { - for (gi, gate) in tick.gate_batches().iter().enumerate() { + for gate in tick.iter_gate_batches() { + let gi = gate.batch_index(); let qubits: Vec = gate.qubits.iter().copied().collect(); if is_rotation(gate.gate_type) @@ -859,7 +862,8 @@ impl CircuitPass for PeepholeOptimize { // Build per-qubit timeline: Vec of (tick_idx, gate_idx) in order. let mut timelines: HashMap> = HashMap::new(); for (ti, tick) in circuit.iter_ticks() { - for (gi, gate) in tick.gate_batches().iter().enumerate() { + for gate in tick.iter_gate_batches() { + let gi = gate.batch_index(); for &q in &gate.qubits { timelines.entry(q).or_default().push((ti, gi)); } @@ -1054,12 +1058,13 @@ impl CircuitPass for AbsorbBasisGates { // Forward scan: absorb Z-diagonal gates after Z-preps. let mut z_eigenstate: HashSet = HashSet::new(); for (ti, tick) in circuit.iter_ticks() { - for (gi, gate) in tick.gate_batches().iter().enumerate() { + for gate in tick.iter_gate_batches() { + let gi = gate.batch_index(); if is_z_prep(gate.gate_type) { for &q in &gate.qubits { z_eigenstate.insert(q); } - } else if is_z_diagonal(gate) + } else if is_z_diagonal(gate.as_gate()) && gate.qubits.iter().all(|q| z_eigenstate.contains(q)) { to_remove.push((ti, gi)); @@ -1184,12 +1189,12 @@ impl CircuitPass for CompactTicks { // Collect every gate together with its per-gate attributes. let mut entries: Vec<(Gate, BTreeMap)> = Vec::new(); for tick in circuit.ticks() { - for (gi, gate) in tick.gate_batches().iter().enumerate() { - let attrs: BTreeMap = tick - .gate_attrs(gi) + for gate in tick.iter_gate_batches() { + let attrs: BTreeMap = gate + .attrs() .map(|(k, v)| (k.clone(), v.clone())) .collect(); - entries.push((gate.clone(), attrs)); + entries.push((gate.as_gate().clone(), attrs)); } } @@ -1774,13 +1779,12 @@ mod tests { let mut tick_ops: Vec = Vec::new(); for tick in tc.ticks() { - let gates = tick.gate_batches(); - if gates.is_empty() { + if tick.is_empty() { continue; } let mut gate_ops: Vec = Vec::new(); - for gate in gates { - let op = gate_to_unitary(gate)?; + for gate in tick.iter_gate_batches() { + let op = gate_to_unitary(gate.as_gate())?; gate_ops.push(op); } // Tensor all gates in this tick (they act on disjoint qubits). @@ -2860,9 +2864,9 @@ mod tests { let mut saw_rewritten = false; let mut saw_untouched = false; - for (idx, gate) in middle.gate_batches().iter().enumerate() { + for gate in middle.iter_gate_batches() { assert_eq!( - middle.get_gate_attr(idx, "calibration"), + gate.get_attr("calibration"), Some(&Attribute::String("entangler".into())) ); match gate.gate_type { diff --git a/crates/pecos-simulators/src/circuit_executor.rs b/crates/pecos-simulators/src/circuit_executor.rs index e4cf66735..92c23ed77 100644 --- a/crates/pecos-simulators/src/circuit_executor.rs +++ b/crates/pecos-simulators/src/circuit_executor.rs @@ -78,8 +78,8 @@ impl<'a> CircuitExecutor<'a> { let mut measurements = Vec::new(); for (_tick_idx, tick) in self.circuit.iter_ticks_batched() { - for batch in tick.gate_batches() { - Self::execute_gate_batch(sim, batch, &mut measurements); + for batch in tick.iter_gate_batches() { + Self::execute_gate_batch(sim, batch.as_gate(), &mut measurements); } } diff --git a/exp/pecos-eeg/src/builder.rs b/exp/pecos-eeg/src/builder.rs index 7faca6a85..96cc5c5d5 100644 --- a/exp/pecos-eeg/src/builder.rs +++ b/exp/pecos-eeg/src/builder.rs @@ -289,7 +289,10 @@ mod tests { .build(); // Manual path - let gates: Vec = tc.iter_gate_batches().cloned().collect(); + let gates: Vec = tc + .iter_gate_batches() + .map(|batch| batch.as_gate().clone()) + .collect(); let expanded = expand::expand_circuit(&gates); let result = circuit::analyze_expanded(&expanded.gates, &noise); diff --git a/exp/pecos-eeg/tests/surface_code.rs b/exp/pecos-eeg/tests/surface_code.rs index f20577cab..cfb30fc0b 100644 --- a/exp/pecos-eeg/tests/surface_code.rs +++ b/exp/pecos-eeg/tests/surface_code.rs @@ -33,7 +33,10 @@ fn build_repetition_code() -> (Vec, Vec, Vec) { // Final data readout tc.tick().mz(&[0, 1, 2]); - let gates: Vec = tc.iter_gate_batches().cloned().collect(); + let gates: Vec = tc + .iter_gate_batches() + .map(|batch| batch.as_gate().clone()) + .collect(); // Detector stabilizers: X on ancilla qubit (anticommutes with Z errors // that propagate through CX from data qubits). @@ -168,7 +171,10 @@ fn test_eeg_generator_count_scales_linearly() { } tc.tick().mz(&[0, 1, 2]); - let gates: Vec = tc.iter_gate_batches().cloned().collect(); + let gates: Vec = tc + .iter_gate_batches() + .map(|batch| batch.as_gate().clone()) + .collect(); let expanded = expand::expand_circuit(&gates); let noise = NoiseModel::coherent_only(0.1); let result = analyze_expanded(&expanded.gates, &noise); diff --git a/exp/pecos-neo/src/circuit.rs b/exp/pecos-neo/src/circuit.rs index 629c4b2b9..d2911b78c 100644 --- a/exp/pecos-neo/src/circuit.rs +++ b/exp/pecos-neo/src/circuit.rs @@ -194,8 +194,8 @@ impl From<&TickCircuit> for CommandQueue { let mut queue = CommandQueue::new(); for tick in circuit.ticks() { - for gate in tick.gate_batches() { - queue.push(gate.into()); + for gate in tick.iter_gate_batches() { + queue.push(gate.as_gate().into()); } } diff --git a/exp/pecos-neo/src/engines.rs b/exp/pecos-neo/src/engines.rs index 075e60269..4c482a07b 100644 --- a/exp/pecos-neo/src/engines.rs +++ b/exp/pecos-neo/src/engines.rs @@ -138,8 +138,8 @@ impl CommandSource for TickCircuitEngine { self.current_tick += 1; let mut queue = CommandQueue::new(); - for gate in tick.gate_batches() { - queue.push(gate.into()); + for gate in tick.iter_gate_batches() { + queue.push(gate.as_gate().into()); } Some(queue) diff --git a/exp/pecos-neo/src/inline_channel.rs b/exp/pecos-neo/src/inline_channel.rs index 1b09a4769..e9f9830d9 100644 --- a/exp/pecos-neo/src/inline_channel.rs +++ b/exp/pecos-neo/src/inline_channel.rs @@ -108,8 +108,8 @@ pub fn run_inline_channels_density_matrix( let mut row = Vec::new(); for tick in circuit.ticks() { - for gate in tick.gate_batches() { - row.extend(apply_gate_to_density_matrix(&mut sim, gate)?); + for gate in tick.iter_gate_batches() { + row.extend(apply_gate_to_density_matrix(&mut sim, gate.as_gate())?); } } @@ -145,9 +145,11 @@ pub fn run_inline_pauli_channels_stabilizer( let mut row = Vec::new(); for tick in circuit.ticks() { - for gate in tick.gate_batches() { + for gate in tick.iter_gate_batches() { row.extend(apply_gate_to_stabilizer_with_pauli_channels( - &mut sim, gate, &mut rng, + &mut sim, + gate.as_gate(), + &mut rng, )?); } } From 7fe380875ce15636af039179a26794748755702e Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 16:49:08 -0600 Subject: [PATCH 115/125] Polish TickCircuit gate batch APIs --- .../benches/modules/tick_circuit_layout.rs | 6 +- .../src/fault_tolerance/fault_sampler.rs | 93 ++++---- crates/pecos-quantum/src/pass.rs | 51 ++--- crates/pecos-quantum/src/tick_circuit.rs | 215 +++++++++--------- .../pecos-simulators/src/circuit_executor.rs | 2 +- python/pecos-rslib/pecos_rslib.pyi | 5 + 6 files changed, 184 insertions(+), 188 deletions(-) diff --git a/crates/benchmarks/benches/modules/tick_circuit_layout.rs b/crates/benchmarks/benches/modules/tick_circuit_layout.rs index 1550bfb71..cf020824c 100644 --- a/crates/benchmarks/benches/modules/tick_circuit_layout.rs +++ b/crates/benchmarks/benches/modules/tick_circuit_layout.rs @@ -10,11 +10,11 @@ // or implied. See the License for the specific language governing permissions and limitations under // the License. -//! TickCircuit batched layout benchmarks. +//! `TickCircuit` batched layout benchmarks. //! //! These benchmarks measure the current batched `TickCircuit` access patterns: -//! - direct TickCircuit traversal, -//! - explicit batched TickCircuit traversal, and +//! - direct `TickCircuit` traversal, +//! - explicit batched `TickCircuit` traversal, and //! - direct vs `CircuitExecutor` simulator execution. use criterion::{BenchmarkId, Criterion, Throughput, measurement::Measurement}; diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index 841550997..db1ffee17 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -251,64 +251,36 @@ fn validate_tick_circuit(tc: &TickCircuit) -> Result<(), UnsupportedGateError> { Ok(()) } -/// Flatten a `TickCircuit` into a gate list with measurement position tracking. +/// Flatten a `TickCircuit` into individual gate applications with measurement +/// position tracking. /// -/// Multi-qubit gates are split into individual entries so each measurement/pair -/// gets its own position for fault injection. Returns the gate list and a map -/// from gate-list index to measurement index. +/// Stored batches are expanded through `TickCircuit`'s `GateInstanceRef` +/// iterator so the qubit/measurement-id slicing semantics are shared with +/// other consumers. Each measurement and each multi-qubit pair gets its own +/// position for fault injection. Returns the gate list and a map from gate-list +/// index to measurement index. pub(crate) fn flatten_tick_circuit(tc: &TickCircuit) -> (Vec, HashMap) { let mut gates = Vec::new(); let mut meas_positions = HashMap::new(); let mut meas_count = 0usize; for (tick_idx, tick) in tc.iter_ticks() { - for gate in tick.iter_gate_batches() { - let gate_idx = gate.batch_index(); - let qs: Vec = gate.qubits.iter().map(pecos_core::QubitId::index).collect(); - let is_mz = is_supported_measurement_gate(gate.gate_type); - let is_2q = is_standard_2q_clifford_gate(gate.gate_type); - - if is_mz && qs.len() > 1 { - for &q in &qs { - meas_positions.insert(gates.len(), meas_count); - meas_count += 1; - gates.push(GateLoc { - tick: tick_idx, - gate_index: gate_idx, - gate_type: gate.gate_type, - qubits: vec![q], - }); - } - } else if is_2q && qs.len() > 2 { - for pair in qs.chunks(2).filter(|c| c.len() == 2) { - gates.push(GateLoc { - tick: tick_idx, - gate_index: gate_idx, - gate_type: gate.gate_type, - qubits: vec![pair[0], pair[1]], - }); - } - } else if qs.len() > 1 && !is_2q && !is_mz { - for &q in &qs { - gates.push(GateLoc { - tick: tick_idx, - gate_index: gate_idx, - gate_type: gate.gate_type, - qubits: vec![q], - }); - } - } else { - if is_mz { - meas_positions.insert(gates.len(), meas_count); - meas_count += 1; - } - gates.push(GateLoc { - tick: tick_idx, - gate_index: gate_idx, - gate_type: gate.gate_type, - qubits: qs, - }); + for gate in tick.iter_gate_instances() { + let qs: Vec = gate + .qubits() + .iter() + .map(pecos_core::QubitId::index) + .collect(); + if is_supported_measurement_gate(gate.gate_type()) { + meas_positions.insert(gates.len(), meas_count); + meas_count += 1; } + gates.push(GateLoc { + tick: tick_idx, + gate_index: gate.batch_index(), + gate_type: gate.gate_type(), + qubits: qs, + }); } } @@ -2072,6 +2044,27 @@ mod tests { assert_eq!(gates[5].qubits, vec![1]); } + #[test] + fn test_flatten_tick_circuit_skips_zero_gate_metadata_batches() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[QubitId(0)]); + tc.insert_tick(1); + tc.get_tick_mut(1) + .unwrap() + .add_gate(pecos_core::Gate::simple( + GateType::PauliOperatorMeta, + vec![QubitId(1), QubitId(2)], + )); + tc.tick().mz(&[QubitId(0)]); + + let (gates, meas_positions) = flatten_tick_circuit(&tc); + + assert_eq!(gates.len(), 2); + assert_eq!(gates[0].gate_type, GateType::H); + assert_eq!(gates[1].gate_type, GateType::MZ); + assert_eq!(meas_positions.get(&1), Some(&0)); + } + // ---- Direct propagation tests using propagate_single ---- #[test] diff --git a/crates/pecos-quantum/src/pass.rs b/crates/pecos-quantum/src/pass.rs index 1a7e39028..51e3e6870 100644 --- a/crates/pecos-quantum/src/pass.rs +++ b/crates/pecos-quantum/src/pass.rs @@ -231,7 +231,7 @@ impl CircuitPass for InsertIdleAfterTwoQubitGates { let mut new_ticks = Vec::with_capacity(circuit.ticks().len() * 2); // Drain ticks from circuit and rebuild with idle insertions - let old_ticks: Vec<_> = std::mem::take(circuit.ticks_vec_mut()); + let old_ticks = circuit.take_ticks(); for tick in old_ticks { let mut idle_qubits: Vec = Vec::new(); @@ -256,7 +256,7 @@ impl CircuitPass for InsertIdleAfterTwoQubitGates { } } - *circuit.ticks_vec_mut() = new_ticks; + circuit.replace_ticks(new_ticks); } fn apply_dag(&self, _circuit: &mut DagCircuit) { @@ -443,7 +443,7 @@ fn peephole_conjugation(middle: &Gate, h_qubit: QubitId) -> Option<(GateType, Ga } fn split_batched_tick_commands(circuit: &mut TickCircuit) { - let old_ticks = std::mem::take(circuit.ticks_vec_mut()); + let old_ticks = circuit.take_ticks(); let mut new_ticks = Vec::with_capacity(old_ticks.len()); for old_tick in old_ticks { @@ -459,9 +459,22 @@ fn split_batched_tick_commands(circuit: &mut TickCircuit) { .map(|(key, value)| (key.clone(), value.clone())) .collect(); - if gate.num_gates() <= 1 { + let split_gates: Vec = if batch.gate_count() == 0 { + vec![gate.clone()] + } else { + batch + .iter_gate_instances() + .map(super::tick_circuit::GateInstanceRef::to_gate) + .collect() + }; + + if split_gates.is_empty() { + continue; + } + + if split_gates.len() == 1 { let new_idx = new_tick - .try_add_gate_preserving_command(gate.clone()) + .try_add_gate_preserving_command(split_gates[0].clone()) .unwrap_or_else(|err| panic!("{err}")); if !attrs.is_empty() { new_tick.set_gate_attrs(new_idx, attrs); @@ -469,25 +482,7 @@ fn split_batched_tick_commands(circuit: &mut TickCircuit) { continue; } - let arity = gate.gate_type.quantum_arity(); - for (instance_idx, qubits) in gate.qubits.chunks(arity).enumerate() { - if qubits.len() != arity { - continue; - } - - let mut split_gate = gate.clone(); - split_gate.qubits = qubits.iter().copied().collect(); - if gate.meas_ids.is_empty() { - split_gate.meas_ids.clear(); - } else { - let meas_start = instance_idx * arity; - let meas_end = meas_start + arity; - split_gate.meas_ids = gate.meas_ids[meas_start..meas_end] - .iter() - .copied() - .collect(); - } - + for split_gate in split_gates { let new_idx = new_tick .try_add_gate_preserving_command(split_gate) .unwrap_or_else(|err| panic!("{err}")); @@ -500,7 +495,7 @@ fn split_batched_tick_commands(circuit: &mut TickCircuit) { new_ticks.push(new_tick); } - *circuit.ticks_vec_mut() = new_ticks; + circuit.replace_ticks(new_ticks); } impl CircuitPass for SimplifyRotations { @@ -1190,10 +1185,8 @@ impl CircuitPass for CompactTicks { let mut entries: Vec<(Gate, BTreeMap)> = Vec::new(); for tick in circuit.ticks() { for gate in tick.iter_gate_batches() { - let attrs: BTreeMap = gate - .attrs() - .map(|(k, v)| (k.clone(), v.clone())) - .collect(); + let attrs: BTreeMap = + gate.attrs().map(|(k, v)| (k.clone(), v.clone())).collect(); entries.push((gate.as_gate().clone(), attrs)); } } diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index 850c72c8c..fcdd0a07c 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -60,6 +60,9 @@ //! circuit3.tick().h(&[0, 1, 2, 3]); // H on 4 qubits at once //! circuit3.tick().cx(&[(0, 1), (2, 3)]); // 2 CX gates in parallel //! circuit3.tick().mz(&[0, 1, 2, 3]); // Measure all 4 qubits +//! +//! assert_eq!(circuit3.gate_count(), 14); // individual gate applications +//! assert_eq!(circuit3.gate_batch_count(), 4); // stored same-type batches //! ``` use pecos_core::gate_type::GateType; @@ -591,6 +594,25 @@ impl<'a> GateInstanceRef<'a> { pub fn attrs(self) -> impl Iterator { self.batch.attrs() } + + /// Materialize this individual gate as an owned [`Gate`]. + /// + /// The returned gate carries this instance's sliced qubits and measurement + /// ids, plus the parent batch's gate type, angles, parameters, and channel + /// payload. Batch metadata is intentionally not copied into the `Gate`; + /// use [`attrs`](Self::attrs) when metadata needs to travel alongside the + /// materialized operation. + #[must_use] + pub fn to_gate(self) -> Gate { + Gate { + gate_type: self.gate_type(), + qubits: self.qubits.iter().copied().collect::(), + angles: self.batch.gate.angles.clone(), + params: self.batch.gate.params.clone(), + meas_ids: self.meas_ids.iter().copied().collect::(), + channel: self.batch.gate.channel.clone(), + } + } } impl Tick { @@ -600,7 +622,7 @@ impl Tick { Self::default() } - /// Get the number of gates in this tick. + /// Get the number of stored gate batches in this tick. /// /// This is the number of stored gate batches. Batched commands such as /// `cx(&[(0, 1), (2, 3)])` count as one stored batch. @@ -609,7 +631,11 @@ impl Tick { self.gate_batches.len() } - /// Get the number of individual gates in this tick. + /// Get the number of individual gate applications in this tick. + /// + /// Batched commands count by the number of gates they represent: + /// `h(&[0, 1, 2])` counts as three H gates, and + /// `cx(&[(0, 1), (2, 3)])` counts as two CX gates. #[must_use] pub fn gate_count(&self) -> usize { self.gate_batches.iter().map(Gate::num_gates).sum() @@ -641,7 +667,7 @@ impl Tick { self.gate_batches.is_empty() } - /// Get the full-fidelity gate batches in this tick. + /// Get the raw stored gate batches in this tick. /// /// In `TickCircuit`, a stored [`Gate`] command may represent one or more /// individual gates on disjoint qubits. For example, @@ -649,6 +675,12 @@ impl Tick { /// /// The batches preserve the complete [`Gate`] payload, including /// measurement IDs and typed channel payloads. + /// + /// Prefer [`iter_gate_batches`](Self::iter_gate_batches) for new read-only + /// consumers; it returns [`GateBatchRef`] values that carry the batch index + /// and metadata alongside the underlying `Gate`. This raw slice accessor is + /// kept for compatibility, storage inspection, and code that intentionally + /// needs stable batch indices. #[must_use] pub fn gate_batches(&self) -> &[Gate] { self.gate_batches.as_slice() @@ -656,9 +688,10 @@ impl Tick { /// Iterate over full-fidelity borrowed gate-batch views in this tick. pub fn iter_gate_batches(&self) -> impl Iterator> { - self.gate_batches.iter().enumerate().map(|(idx, gate)| { - GateBatchRef::new(idx, gate, self.normalized_gate_attrs(idx)) - }) + self.gate_batches + .iter() + .enumerate() + .map(|(idx, gate)| GateBatchRef::new(idx, gate, self.normalized_gate_attrs(idx))) } /// Iterate over individual gates expanded from this tick's stored batches. @@ -832,6 +865,10 @@ impl Tick { /// Set metadata on a gate. /// /// Returns the gate index. + /// + /// # Panics + /// + /// Panics if `gate_idx` is not a valid stored batch index in this tick. pub fn set_gate_attr(&mut self, gate_idx: usize, key: &str, value: Attribute) -> usize { assert!( gate_idx < self.gate_batches.len(), @@ -846,6 +883,10 @@ impl Tick { /// Set multiple metadata attributes on a gate at once. /// /// Returns the gate index. + /// + /// # Panics + /// + /// Panics if `gate_idx` is not a valid stored batch index in this tick. pub fn set_gate_attrs(&mut self, gate_idx: usize, attrs: BTreeMap) -> usize { assert!( gate_idx < self.gate_batches.len(), @@ -1336,7 +1377,7 @@ impl TickCircuit { self.next_meas_record += n; } - /// Get the total number of gates across all ticks. + /// Get the total number of individual gate applications across all ticks. /// /// Batched commands count by individual gate. For example, /// `cx(&[(0, 1), (2, 3)])` contributes two gates. @@ -1396,6 +1437,13 @@ impl TickCircuit { } /// Get a mutable tick by index. + /// + /// Mutating a tick through this handle must preserve the usual + /// `TickCircuit` invariants: each stored [`Gate`] must validate, qubits may + /// not overlap within a tick, and gate metadata must stay aligned with the + /// stored batches. Prefer `Tick` methods such as + /// [`Tick::add_gate`], [`Tick::remove_gate`], and + /// [`Tick::replace_gate_batch`] over direct structural rewrites. pub fn get_tick_mut(&mut self, idx: usize) -> Option<&mut Tick> { self.ticks.get_mut(idx) } @@ -1406,15 +1454,35 @@ impl TickCircuit { &self.ticks } - /// Get mutable access to all ticks (slice). + /// Get mutable access to all ticks as a slice. + /// + /// This is an escape hatch for passes that need to mutate existing ticks in + /// place. Do not reorder, insert, or remove ticks through this slice. Keep + /// each tick's gate/metadata invariants intact by using `Tick` mutation + /// methods rather than editing stored batches directly. pub fn ticks_mut(&mut self) -> &mut [Tick] { &mut self.ticks } - /// Get mutable access to the ticks vector (for structural passes that - /// need to insert/remove ticks). - pub fn ticks_vec_mut(&mut self) -> &mut Vec { - &mut self.ticks + /// Remove all ticks from this circuit for an internal structural rewrite. + /// + /// This is crate-private because a partially drained circuit has + /// temporarily invalid tick structure. Pair it with + /// [`replace_ticks`](Self::replace_ticks) in the same transformation. + pub(crate) fn take_ticks(&mut self) -> Vec { + let ticks = std::mem::take(&mut self.ticks); + self.next_tick = 0; + ticks + } + + /// Replace all ticks after an internal structural rewrite. + /// + /// Updates `next_tick` to match the replacement length. The caller remains + /// responsible for preserving measurement record numbering, annotation + /// references, tick ordering, and each tick's gate/metadata alignment. + pub(crate) fn replace_ticks(&mut self, ticks: Vec) { + self.ticks = ticks; + self.next_tick = self.ticks.len(); } /// Export as a plain ASCII circuit diagram. @@ -1734,9 +1802,10 @@ impl TickCircuit { /// Returns an error if the source circuit already contains channel /// operations. Apply either inline channels or a noise model, not both. pub fn try_with_noise(&self, noise: &N) -> Result { - for (tick_idx, tick) in self.ticks.iter().enumerate() { - for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { + for (tick_idx, tick) in self.iter_ticks() { + for gate in tick.iter_gate_batches() { if gate.is_channel() { + let gate_idx = gate.batch_index(); return Err(format!( "with_noise cannot apply a noise model to a circuit that already contains channel operations (first channel at tick {tick_idx} gate {gate_idx})" )); @@ -1754,8 +1823,8 @@ impl TickCircuit { out.ticks.push(tick.clone()); let mut noise_ticks = Vec::new(); - for gate in tick.gate_batches() { - for channel in noise.channels_after(gate) { + for gate in tick.iter_gate_batches() { + for channel in noise.channels_after(gate.as_gate()) { schedule_channel_gate(&mut noise_ticks, Gate::channel(channel)); } } @@ -1986,9 +2055,10 @@ impl TickCircuit { /// Iterate over full-fidelity gate batches with their tick index. pub fn iter_gate_batches_with_tick(&self) -> impl Iterator)> { - self.ticks.iter().enumerate().flat_map(|(tick_idx, tick)| { - tick.iter_gate_batches().map(move |gate| (tick_idx, gate)) - }) + self.ticks + .iter() + .enumerate() + .flat_map(|(tick_idx, tick)| tick.iter_gate_batches().map(move |gate| (tick_idx, gate))) } /// Iterate over individual gates expanded from stored batches. @@ -2025,16 +2095,6 @@ impl TickCircuit { self.ticks.iter().enumerate() } - /// Iterate over ticks through the batched command view. - /// - /// This is currently equivalent to [`iter_ticks`](Self::iter_ticks), because - /// each [`Tick`] stores full-fidelity gate batches. It exists so - /// batched consumers can depend on `TickCircuit` directly instead of a - /// converted execution-only circuit representation. - pub fn iter_ticks_batched(&self) -> impl Iterator { - self.iter_ticks() - } - /// Iterate over gates filtered by gate type. /// /// # Examples @@ -3256,71 +3316,18 @@ impl From<&TickCircuit> for DagCircuit { let mut meas_record_idx = 0usize; for (tick_idx, tick) in tc.iter_ticks() { - for (gate_idx, gate) in tick.gate_batches().iter().enumerate() { - // Split batched gates into individual operations. - // - // TickCircuit batches gates for efficiency: - // - 1q gates: H([0,1,2]) = one gate with 3 qubits - // - 2q gates: CX([0,1, 2,3]) = one gate with 4 qubits (2 pairs) - // - // DagCircuit needs individual gates for correct fault analysis. - // Without splitting, a 4-qubit MZ generates 2^4-1=15 fault combos - // instead of 4 independent X faults. A 12-qubit CX generates - // 4^12=16M combos instead of 6×15=90. - let is_two_qubit = matches!( - gate.gate_type, - GateType::CX - | GateType::CY - | GateType::CZ - | GateType::SWAP - | GateType::RXX - | GateType::RYY - | GateType::RZZ - | GateType::SXX - | GateType::SXXdg - | GateType::SYY - | GateType::SYYdg - | GateType::SZZ - | GateType::SZZdg - ); - let needs_split = if gate.is_channel() { - false - } else if is_two_qubit { - gate.qubits.len() > 2 + for batch in tick.iter_gate_batches() { + // DagCircuit stores individual gate applications. Use the + // TickCircuit instance view so qubit/meas-id slicing has one + // implementation. Zero-gate metadata batches do not have gate + // instances, so keep their stored command as a single DAG node. + let split_gates: Vec = if batch.gate_count() == 0 { + vec![batch.as_gate().clone()] } else { - gate.qubits.len() > 1 - }; - - let split_gates: Vec = if needs_split { - let chunk_size = if is_two_qubit { 2 } else { 1 }; - gate.qubits - .chunks(chunk_size) - .filter(|chunk| chunk.len() == chunk_size) - .enumerate() - .map(|(chunk_idx, qs)| { - // For measurement gates, distribute MeasId values - // to the split gates (one per qubit). - let mr = if gate.meas_ids.is_empty() { - GateMeasIds::new() - } else { - let start = chunk_idx * chunk_size; - gate.meas_ids - .get(start..start + chunk_size) - .map(|s| s.iter().copied().collect::()) - .unwrap_or_default() - }; - Gate { - gate_type: gate.gate_type, - qubits: qs.iter().copied().collect::(), - angles: gate.angles.clone(), - params: gate.params.clone(), - meas_ids: mr, - channel: gate.channel.clone(), - } - }) + batch + .iter_gate_instances() + .map(GateInstanceRef::to_gate) .collect() - } else { - vec![gate.clone()] }; let mut split_nodes = Vec::with_capacity(split_gates.len()); @@ -3346,7 +3353,7 @@ impl From<&TickCircuit> for DagCircuit { } // Copy batch-level gate attributes to every split gate. - for (key, value) in tick.gate_attrs(gate_idx) { + for (key, value) in batch.attrs() { for &node in &split_nodes { dag.set_gate_attr(node, key, value.clone()); } @@ -5271,6 +5278,10 @@ mod tests { assert_eq!(instances_with_tick[0].1.instance_index(), 0); assert_eq!(instances_with_tick[0].1.gate_type(), GateType::H); assert_eq!(instances_with_tick[0].1.qubits(), &[QubitId::from(0)]); + assert_eq!( + instances_with_tick[0].1.to_gate().qubits.as_slice(), + &[QubitId::from(0)] + ); assert_eq!( instances_with_tick[0].1.get_attr("calibration"), Some(&Attribute::String("h-cal".into())) @@ -5292,16 +5303,16 @@ mod tests { assert_eq!(instances_with_tick[6].1.gate_type(), GateType::MZ); assert_eq!(instances_with_tick[6].1.qubits(), &[QubitId::from(0)]); assert_eq!(instances_with_tick[6].1.meas_ids(), &[MeasId(0)]); + assert_eq!( + instances_with_tick[6].1.to_gate().meas_ids.as_slice(), + &[MeasId(0)] + ); assert_eq!(instances_with_tick[9].1.meas_ids(), &[MeasId(3)]); // Test iter_ticks let ticks: Vec<_> = tc.iter_ticks().collect(); assert_eq!(ticks.len(), 3); - let batched_ticks: Vec<_> = tc.iter_ticks_batched().collect(); - assert_eq!(batched_ticks.len(), 3); - assert_eq!(batched_ticks[1].1.gate_batches()[0].gate_type, GateType::CX); - // Test iter_gates_by_type let h_gates: Vec<_> = tc.iter_gates_by_type(GateType::H).collect(); assert_eq!(h_gates.len(), 1); @@ -5647,14 +5658,8 @@ mod tests { assert_eq!(tick.len(), 2); assert_eq!(tick.gate_batches()[0].gate_type, GateType::X); assert_eq!(tick.gate_batches()[1].gate_type, GateType::Z); - assert_eq!( - tick.get_gate_attr(0, "x_attr"), - Some(&Attribute::Int(2)) - ); - assert_eq!( - tick.get_gate_attr(1, "z_attr"), - Some(&Attribute::Int(3)) - ); + assert_eq!(tick.get_gate_attr(0, "x_attr"), Some(&Attribute::Int(2))); + assert_eq!(tick.get_gate_attr(1, "z_attr"), Some(&Attribute::Int(3))); assert!(tick.get_gate_attr(0, "h_attr").is_none()); } diff --git a/crates/pecos-simulators/src/circuit_executor.rs b/crates/pecos-simulators/src/circuit_executor.rs index 92c23ed77..18261f0d1 100644 --- a/crates/pecos-simulators/src/circuit_executor.rs +++ b/crates/pecos-simulators/src/circuit_executor.rs @@ -77,7 +77,7 @@ impl<'a> CircuitExecutor<'a> { pub fn run(&self, sim: &mut S) -> Vec { let mut measurements = Vec::new(); - for (_tick_idx, tick) in self.circuit.iter_ticks_batched() { + for (_tick_idx, tick) in self.circuit.iter_ticks() { for batch in tick.iter_gate_batches() { Self::execute_gate_batch(sim, batch.as_gate(), &mut measurements); } diff --git a/python/pecos-rslib/pecos_rslib.pyi b/python/pecos-rslib/pecos_rslib.pyi index 5a2d04aac..167e43e53 100644 --- a/python/pecos-rslib/pecos_rslib.pyi +++ b/python/pecos-rslib/pecos_rslib.pyi @@ -1504,9 +1504,11 @@ class Tick: def gate_count(self) -> int: """Number of individual gate applications in this tick.""" ... + def gate_batch_count(self) -> int: """Number of stored compatible gate batches in this tick.""" ... + def is_empty(self) -> bool: ... def gate_batches(self) -> list[Gate]: ... def get_gate_attr(self, gate_idx: int, key: str) -> Any | None: ... @@ -1609,13 +1611,16 @@ class TickCircuit: def tick(self) -> TickHandle: """Add a new tick and return a handle for adding gates.""" ... + def num_ticks(self) -> int: ... def gate_count(self) -> int: """Total number of individual gate applications.""" ... + def gate_batch_count(self) -> int: """Total number of stored compatible gate batches.""" ... + def num_measurements(self) -> int: ... def next_tick_index(self) -> int: ... def get_tick(self, idx: int) -> Tick | None: ... From 17f5cbfbdd87f0075a4f0060c94f3c89f724210c Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 20:10:17 -0600 Subject: [PATCH 116/125] Fix stale maturin extension artifacts --- crates/pecos-cli/src/cli/python_cmd.rs | 113 ++++++++++++++++++++++++- 1 file changed, 112 insertions(+), 1 deletion(-) diff --git a/crates/pecos-cli/src/cli/python_cmd.rs b/crates/pecos-cli/src/cli/python_cmd.rs index 565f6aa73..aecc765b9 100644 --- a/crates/pecos-cli/src/cli/python_cmd.rs +++ b/crates/pecos-cli/src/cli/python_cmd.rs @@ -3,7 +3,7 @@ use pecos_build::Result; use pecos_build::errors::Error; use std::fs; -use std::path::PathBuf; +use std::path::{Path, PathBuf}; use std::process::Command; /// Run the python subcommand @@ -118,6 +118,8 @@ fn run_build(profile: &str, rustflags: Option<&str>, cuda: bool) -> Result<()> { } ); + remove_stale_extension_artifacts(&repo_root, profile, crate_name)?; + let maturin = venv_bin.join("maturin"); let mut cmd = Command::new(&maturin); cmd.args(["develop", "--uv"]); @@ -192,3 +194,112 @@ fn run_build(profile: &str, rustflags: Option<&str>, cuda: bool) -> Result<()> { ))), } } + +fn cargo_profile_dir(profile: &str) -> &'static str { + if matches!(profile, "release" | "native") { + "release" + } else { + "debug" + } +} + +fn extension_library_filename(crate_name: &str) -> String { + let module_name = crate_name.replace('-', "_"); + + #[cfg(target_os = "windows")] + { + format!("{module_name}.dll") + } + + #[cfg(target_os = "macos")] + { + format!("lib{module_name}.dylib") + } + + #[cfg(all(unix, not(target_os = "macos")))] + { + format!("lib{module_name}.so") + } +} + +fn extension_artifact_candidates( + repo_root: &Path, + profile: &str, + crate_name: &str, +) -> [PathBuf; 3] { + let filename = extension_library_filename(crate_name); + let target_dir = repo_root.join("target"); + let profile_dir = target_dir.join(cargo_profile_dir(profile)); + + [ + profile_dir.join(&filename), + profile_dir.join("deps").join(&filename), + target_dir.join("maturin").join(&filename), + ] +} + +fn remove_stale_extension_artifacts( + repo_root: &Path, + profile: &str, + crate_name: &str, +) -> Result<()> { + let [profile_artifact, deps_artifact, maturin_staging_artifact] = + extension_artifact_candidates(repo_root, profile, crate_name); + + for path in [profile_artifact, deps_artifact] { + match fs::metadata(&path) { + Ok(metadata) if metadata.is_file() && metadata.len() == 0 => { + println!( + "Removing zero-byte extension artifact before rebuild: {}", + path.display() + ); + fs::remove_file(path)?; + } + Ok(_) => {} + Err(err) if err.kind() == std::io::ErrorKind::NotFound => {} + Err(err) => return Err(err.into()), + } + } + + match fs::metadata(&maturin_staging_artifact) { + Ok(metadata) if metadata.is_file() => { + println!( + "Removing stale maturin staging artifact before rebuild: {}", + maturin_staging_artifact.display() + ); + fs::remove_file(maturin_staging_artifact)?; + } + Ok(_) => {} + Err(err) if err.kind() == std::io::ErrorKind::NotFound => {} + Err(err) => return Err(err.into()), + } + + Ok(()) +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn cargo_profile_dir_maps_native_to_release() { + assert_eq!(cargo_profile_dir("debug"), "debug"); + assert_eq!(cargo_profile_dir("release"), "release"); + assert_eq!(cargo_profile_dir("native"), "release"); + } + + #[test] + fn extension_artifact_candidates_use_python_module_name() { + let repo = PathBuf::from("/repo"); + let candidates = extension_artifact_candidates(&repo, "debug", "pecos-rslib-llvm"); + let filename = extension_library_filename("pecos-rslib-llvm"); + + assert!(filename.contains("pecos_rslib_llvm")); + assert_eq!(candidates[0], repo.join("target/debug").join(&filename)); + assert_eq!( + candidates[1], + repo.join("target/debug/deps").join(&filename) + ); + assert_eq!(candidates[2], repo.join("target/maturin").join(&filename)); + } +} From 60598eac770d73f5992adbe40912d7711bd730d1 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 20:28:58 -0600 Subject: [PATCH 117/125] Polish DEM tracking and gate handling --- .../benches/modules/gpu_influence_sampler.rs | 4 +- crates/pecos-core/src/gate_type.rs | 46 +- crates/pecos-core/src/gates.rs | 4 +- crates/pecos-cuquantum/src/lib.rs | 37 ++ .../src/noise/biased_depolarizing.rs | 2 +- .../pecos-engines/src/noise/depolarizing.rs | 2 +- crates/pecos-engines/src/quantum.rs | 4 +- .../examples/cpu_vs_gpu_comparison.rs | 8 +- .../examples/full_pipeline_example.rs | 4 +- .../examples/pipeline_benchmark.rs | 16 +- .../examples/profile_samplers.rs | 4 +- crates/pecos-gpu-sims/src/gpu_pauli_prop.rs | 6 +- .../pecos-hugr/src/engine/control_flow/cfg.rs | 14 +- crates/pecos-qasm/src/engine.rs | 2 +- crates/pecos-qec/src/fault_tolerance.rs | 2 +- .../fault_tolerance/dem_builder/builder.rs | 80 ++-- .../dem_builder/dem_sampler.rs | 10 +- .../dem_builder/equivalence.rs | 156 +++--- .../fault_tolerance/dem_builder/sampler.rs | 270 +++++------ .../src/fault_tolerance/dem_builder/types.rs | 445 ++++++++++-------- .../src/fault_tolerance/fault_sampler.rs | 233 ++++----- .../src/fault_tolerance/influence_builder.rs | 61 ++- .../src/fault_tolerance/lookup_decoder.rs | 6 +- .../src/fault_tolerance/propagator.rs | 38 +- .../src/fault_tolerance/propagator/checker.rs | 14 +- .../src/fault_tolerance/propagator/dag.rs | 91 ++-- .../src/fault_tolerance/propagator/tick.rs | 68 +-- .../propagator/tick_batched.rs | 66 +-- .../src/fault_tolerance/propagator/types.rs | 60 +-- .../targeted_lookup_decoder.rs | 10 +- .../tests/fault_enumeration_example.rs | 20 +- crates/pecos-qec/tests/targeted_tests.rs | 6 +- .../pecos-qec/tests/unified_sampler_tests.rs | 4 +- crates/pecos-quantum/src/circuit_display.rs | 4 +- crates/pecos-quantum/src/dag_circuit.rs | 42 +- crates/pecos-quantum/src/pass.rs | 73 +++ crates/pecos-quantum/src/tick_circuit.rs | 151 ++++-- crates/pecos-quantum/src/unitary_matrix.rs | 2 +- .../src/bitmask_pauli_prop.rs | 2 +- .../pecos-simulators/src/quantum_simulator.rs | 2 +- docs/README.md | 2 +- docs/user-guide/fault-catalog.md | 28 +- docs/user-guide/getting-started.md | 2 +- docs/user-guide/pecos-concepts.md | 18 +- examples/surface/README.md | 2 +- examples/surface_code_noisy_decoding.ipynb | 2 +- examples/surface_code_selene_demo.ipynb | 4 +- examples/surface_code_slr_exploration.ipynb | 2 +- examples/surface_code_threshold.ipynb | 2 +- exp/pecos-eeg/src/builder.rs | 2 +- exp/pecos-experimental/src/hugr_executor.rs | 2 +- exp/pecos-stab-tn/src/stab_mps.rs | 39 +- python/pecos-rslib-cuda/src/lib.rs | 34 +- .../pecos-rslib-exp/src/sim_neo_bindings.rs | 24 +- python/pecos-rslib/pecos_rslib.pyi | 3 +- .../pecos-rslib/src/dag_circuit_bindings.rs | 30 +- .../src/fault_tolerance_bindings.rs | 200 ++++---- .../pecos-rslib/src/gate_registry_bindings.rs | 1 + .../src/pecos/qec/surface/circuit_builder.py | 108 +++-- .../tests/docs/rust_crate/Cargo.lock | 110 ++--- .../tests/user_guide_fault_catalog.rs | 2 +- .../state_sim_tests/test_cuda_simulators.py | 47 +- .../tests/qec/surface/test_circuit_fuzz.py | 2 +- .../tests/qec/test_dem_equivalence.py | 10 +- .../tests/qec/test_dem_sampler.py | 118 +++-- .../tests/qec/test_dem_sampler_modes.py | 2 +- .../tests/qec/test_fault_catalog.py | 12 +- .../tests/qec/test_parsed_dem_sampler.py | 19 +- .../tests/qec/test_qec_ux_entrypoints.py | 35 +- scripts/docs/generate_doc_tests.py | 10 +- scripts/native_bench/bench_pecos/Cargo.lock | 7 +- 71 files changed, 1709 insertions(+), 1239 deletions(-) diff --git a/crates/benchmarks/benches/modules/gpu_influence_sampler.rs b/crates/benchmarks/benches/modules/gpu_influence_sampler.rs index 990b5122c..27f218c6e 100644 --- a/crates/benchmarks/benches/modules/gpu_influence_sampler.rs +++ b/crates/benchmarks/benches/modules/gpu_influence_sampler.rs @@ -105,8 +105,8 @@ fn build_influence_maps( circuit: &DagCircuit, num_data: usize, ) -> (DagFaultInfluenceMap, GpuInfluenceMapData) { - let tracked_op_qubits: Vec = (0..num_data).collect(); - let builder = InfluenceBuilder::new(circuit).with_z(&tracked_op_qubits); + let tracked_pauli_qubits: Vec = (0..num_data).collect(); + let builder = InfluenceBuilder::new(circuit).with_z(&tracked_pauli_qubits); let influence_map = builder.build(); let ( diff --git a/crates/pecos-core/src/gate_type.rs b/crates/pecos-core/src/gate_type.rs index 52f140fe2..2c2c94386 100644 --- a/crates/pecos-core/src/gate_type.rs +++ b/crates/pecos-core/src/gate_type.rs @@ -108,16 +108,16 @@ pub enum GateType { /// Free/deallocate a qubit QFree = 136, Idle = 200, - /// Meta-gate: tracked-operator annotation for fault tracking. + /// Meta-gate: tracked-Pauli annotation for fault tracking. /// /// This gate carries a Pauli string but has no effect on quantum state. - /// Its position in the circuit determines which faults can flip the tracked operator + /// Its position in the circuit determines which faults can flip the tracked Pauli /// (only faults before this node are relevant). The propagator uses it as a /// backward propagation start point. /// /// The Pauli string is encoded in `params`: each param encodes /// `qubit * 4 + pauli_type` where `pauli_type` is 1=X, 2=Y, 3=Z. - PauliOperatorMeta = 210, + TrackedPauliMeta = 210, MeasCrosstalkGlobalPayload = 218, MeasCrosstalkLocalPayload = 219, /// Typed channel operation embedded in an annotated/noisy circuit. @@ -180,7 +180,7 @@ impl From for GateType { 200 => GateType::Idle, 218 => GateType::MeasCrosstalkGlobalPayload, 219 => GateType::MeasCrosstalkLocalPayload, - 210 => GateType::PauliOperatorMeta, + 210 => GateType::TrackedPauliMeta, 220 => GateType::Channel, 255 => GateType::Custom, _ => panic!("Invalid gate type ID: {value}"), @@ -195,7 +195,7 @@ impl GateType { /// and should not create fault locations or receive noise. #[must_use] pub const fn is_meta(self) -> bool { - matches!(self, GateType::PauliOperatorMeta) + matches!(self, GateType::TrackedPauliMeta) } /// Returns the number of angle parameters this gate type requires @@ -244,7 +244,7 @@ impl GateType { | GateType::QAlloc | GateType::QFree | GateType::Custom - | GateType::PauliOperatorMeta => 0, + | GateType::TrackedPauliMeta => 0, // Gates with one parameter GateType::RX @@ -307,12 +307,12 @@ impl GateType { | GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload | GateType::Custom - // PauliOperatorMeta and Channel are variable-arity but return 1 + // TrackedPauliMeta and Channel are variable-arity but return 1 // here because gate validation checks // `is_multiple_of(quantum_arity())` and any count is a multiple // of 1. The actual qubit count is in the gate. | GateType::Channel - | GateType::PauliOperatorMeta => 1, + | GateType::TrackedPauliMeta => 1, // Two-qubit gates GateType::CX @@ -351,7 +351,7 @@ impl GateType { self, GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload - | GateType::PauliOperatorMeta + | GateType::TrackedPauliMeta ) { return 0; } @@ -464,7 +464,7 @@ impl fmt::Display for GateType { GateType::MeasCrosstalkLocalPayload => write!(f, "MeasCrosstalkLocalPayload"), GateType::Channel => write!(f, "Channel"), GateType::Custom => write!(f, "Custom"), - GateType::PauliOperatorMeta => write!(f, "PauliOperator"), + GateType::TrackedPauliMeta => write!(f, "TrackedPauli"), } } } @@ -526,6 +526,7 @@ impl std::str::FromStr for GateType { "QALLOC" => Ok(GateType::QAlloc), "QFREE" => Ok(GateType::QFree), "IDLE" => Ok(GateType::Idle), + "TRACKEDPAULI" | "TRACKEDPAULIMETA" | "TP" => Ok(GateType::TrackedPauliMeta), "CHANNEL" => Ok(GateType::Channel), _ => Err(format!("Unknown gate type: {s}")), } @@ -707,11 +708,34 @@ mod tests { assert_eq!(GateType::CCX.num_gates(6), 2); assert_eq!(GateType::Custom.num_gates(2), 1); assert_eq!(GateType::Channel.num_gates(2), 1); - assert_eq!(GateType::PauliOperatorMeta.num_gates(3), 0); + assert_eq!(GateType::TrackedPauliMeta.num_gates(3), 0); assert_eq!(GateType::MeasCrosstalkGlobalPayload.num_gates(3), 0); assert_eq!(GateType::MeasCrosstalkLocalPayload.num_gates(3), 0); } + #[test] + fn test_tracked_pauli_meta_gate_type_contract() { + assert_eq!( + "TrackedPauli".parse::().unwrap(), + GateType::TrackedPauliMeta + ); + assert_eq!( + "TrackedPauliMeta".parse::().unwrap(), + GateType::TrackedPauliMeta + ); + assert_eq!( + "TP".parse::().unwrap(), + GateType::TrackedPauliMeta + ); + + assert_eq!(GateType::TrackedPauliMeta.to_string(), "TrackedPauli"); + assert_eq!(GateType::TrackedPauliMeta as u8, 210); + assert!(GateType::TrackedPauliMeta.is_meta()); + assert_eq!(GateType::TrackedPauliMeta.classical_arity(), 0); + assert_eq!(GateType::TrackedPauliMeta.quantum_arity(), 1); + assert_eq!(GateType::TrackedPauliMeta.num_gates(4), 0); + } + #[test] fn test_is_parameterized() { // Non-parameterized gates diff --git a/crates/pecos-core/src/gates.rs b/crates/pecos-core/src/gates.rs index 188f30ce5..c03830714 100644 --- a/crates/pecos-core/src/gates.rs +++ b/crates/pecos-core/src/gates.rs @@ -139,7 +139,7 @@ impl Gate { self.gate_type, GateType::Custom | GateType::Channel - | GateType::PauliOperatorMeta + | GateType::TrackedPauliMeta | GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload ) { @@ -1277,7 +1277,7 @@ mod tests { ); assert_eq!( Gate::simple( - GateType::PauliOperatorMeta, + GateType::TrackedPauliMeta, vec![QubitId::from(0), QubitId::from(1)] ) .num_gates(), diff --git a/crates/pecos-cuquantum/src/lib.rs b/crates/pecos-cuquantum/src/lib.rs index 2cf231b17..7d54f46e6 100644 --- a/crates/pecos-cuquantum/src/lib.rs +++ b/crates/pecos-cuquantum/src/lib.rs @@ -89,6 +89,43 @@ pub fn is_cuquantum_available() -> bool { pecos_cuquantum_sys::is_available() } +/// Check if the cuStateVec backend can create a simulator on this machine. +/// +/// This is stricter than [`is_cuquantum_available`]: it verifies not only that +/// cuQuantum libraries can be loaded, but also that a CUDA device/runtime can +/// initialize the cuStateVec handle and allocate a minimal state vector. +#[must_use] +pub fn is_custatevec_usable() -> bool { + CuStateVec::new(1).is_ok() +} + +/// Check if the cuStabilizer backend can create a frame simulator. +/// +/// This is stricter than [`is_cuquantum_available`] and catches environments +/// where the libraries are present but the CUDA runtime cannot initialize. +#[must_use] +pub fn is_custabilizer_usable() -> bool { + CuFrameSimulator::new(1, 1, 1).is_ok() +} + +/// Check if the cuTensorNet backend can create a handle. +/// +/// This is stricter than [`is_cuquantum_available`] and catches environments +/// where the libraries are present but the CUDA runtime cannot initialize. +#[must_use] +pub fn is_cutensornet_usable() -> bool { + CuTensorNet::new().is_ok() +} + +/// Check if the cuDensityMat backend can create a simulator on this machine. +/// +/// This is stricter than [`is_cuquantum_available`] and catches environments +/// where the libraries are present but the CUDA runtime cannot initialize. +#[must_use] +pub fn is_cudensitymat_usable() -> bool { + CuDensityMat::new(1).is_ok() +} + #[cfg(test)] mod tests { use super::*; diff --git a/crates/pecos-engines/src/noise/biased_depolarizing.rs b/crates/pecos-engines/src/noise/biased_depolarizing.rs index 889cd6009..2bd3cce99 100644 --- a/crates/pecos-engines/src/noise/biased_depolarizing.rs +++ b/crates/pecos-engines/src/noise/biased_depolarizing.rs @@ -233,7 +233,7 @@ impl BiasedDepolarizingNoiseModel { | GateType::MeasCrosstalkGlobalPayload | GateType::QFree | GateType::Custom - | GateType::PauliOperatorMeta => {} + | GateType::TrackedPauliMeta => {} } } diff --git a/crates/pecos-engines/src/noise/depolarizing.rs b/crates/pecos-engines/src/noise/depolarizing.rs index 91fccf32a..6f6d3c198 100644 --- a/crates/pecos-engines/src/noise/depolarizing.rs +++ b/crates/pecos-engines/src/noise/depolarizing.rs @@ -245,7 +245,7 @@ impl DepolarizingNoiseModel { | GateType::MeasCrosstalkGlobalPayload | GateType::QFree | GateType::Custom - | GateType::PauliOperatorMeta => { + | GateType::TrackedPauliMeta => { // Just pass through with no added noise. } } diff --git a/crates/pecos-engines/src/quantum.rs b/crates/pecos-engines/src/quantum.rs index 512e6ff8f..9039080cb 100644 --- a/crates/pecos-engines/src/quantum.rs +++ b/crates/pecos-engines/src/quantum.rs @@ -572,7 +572,7 @@ fn process_general_message< | GateType::MeasCrosstalkGlobalPayload | GateType::QFree | GateType::Custom - | GateType::PauliOperatorMeta => {} + | GateType::TrackedPauliMeta => {} } cmd_idx += 1; } @@ -1134,7 +1134,7 @@ where | GateType::MeasCrosstalkGlobalPayload | GateType::QFree | GateType::Custom - | GateType::PauliOperatorMeta => { + | GateType::TrackedPauliMeta => { // Just let the system naturally evolve for the specified duration // No active operation needed in the simulator // QFree is a no-op for state vector simulation (qubit tracking is handled elsewhere) diff --git a/crates/pecos-gpu-sims/examples/cpu_vs_gpu_comparison.rs b/crates/pecos-gpu-sims/examples/cpu_vs_gpu_comparison.rs index e5a948c33..8bf404caa 100644 --- a/crates/pecos-gpu-sims/examples/cpu_vs_gpu_comparison.rs +++ b/crates/pecos-gpu-sims/examples/cpu_vs_gpu_comparison.rs @@ -91,8 +91,8 @@ fn main() { let num_data = distance * distance; // Build influence map - let tracked_op_qubits: Vec = (0..num_data).collect(); - let builder = InfluenceBuilder::new(&circuit).with_z(&tracked_op_qubits); + let tracked_pauli_qubits: Vec = (0..num_data).collect(); + let builder = InfluenceBuilder::new(&circuit).with_z(&tracked_pauli_qubits); let influence_map = builder.build(); let num_locations = influence_map.locations.len(); @@ -179,8 +179,8 @@ fn main() { let circuit = build_surface_code_grid(distance, num_rounds); let num_data = distance * distance; - let tracked_op_qubits: Vec = (0..num_data).collect(); - let builder = InfluenceBuilder::new(&circuit).with_z(&tracked_op_qubits); + let tracked_pauli_qubits: Vec = (0..num_data).collect(); + let builder = InfluenceBuilder::new(&circuit).with_z(&tracked_pauli_qubits); let influence_map = builder.build(); let ( diff --git a/crates/pecos-gpu-sims/examples/full_pipeline_example.rs b/crates/pecos-gpu-sims/examples/full_pipeline_example.rs index 8cdcb25c1..f882e1094 100644 --- a/crates/pecos-gpu-sims/examples/full_pipeline_example.rs +++ b/crates/pecos-gpu-sims/examples/full_pipeline_example.rs @@ -83,7 +83,7 @@ fn main() { let circuit = build_repetition_code_circuit(2); println!(" Circuit built: {} gates", circuit.gate_count()); - // Build influence map with a tracked Z operator (sensitive to X errors) + // Build influence map with a tracked Z Pauli (sensitive to X errors) let builder = InfluenceBuilder::new(&circuit).with_z(&[0, 1, 2]); let influence_map = builder.build(); @@ -158,7 +158,7 @@ fn main() { let circuit = build_surface_code_plaquette(3); println!(" Circuit built: {} gates", circuit.gate_count()); - // Build influence map with a tracked X operator (sensitive to Z errors on this plaquette) + // Build influence map with a tracked X Pauli (sensitive to Z errors on this plaquette) let builder = InfluenceBuilder::new(&circuit).with_x(&[0, 1, 2, 3]); let influence_map = builder.build(); diff --git a/crates/pecos-gpu-sims/examples/pipeline_benchmark.rs b/crates/pecos-gpu-sims/examples/pipeline_benchmark.rs index 87bc7180e..3b28b931a 100644 --- a/crates/pecos-gpu-sims/examples/pipeline_benchmark.rs +++ b/crates/pecos-gpu-sims/examples/pipeline_benchmark.rs @@ -150,14 +150,14 @@ impl BenchmarkResult { fn benchmark_circuit( name: &str, circuit: &DagCircuit, - tracked_op_qubits: &[usize], + tracked_pauli_qubits: &[usize], num_shots: u32, p_error: f64, seed: u64, ) -> BenchmarkResult { // Build influence map (common to both pipelines) let build_start = Instant::now(); - let builder = InfluenceBuilder::new(circuit).with_z(tracked_op_qubits); + let builder = InfluenceBuilder::new(circuit).with_z(tracked_pauli_qubits); let influence_map = builder.build(); let build_time = build_start.elapsed(); @@ -296,13 +296,13 @@ fn main() { for (num_data, num_rounds) in [(3, 2), (5, 3), (7, 4), (9, 5), (11, 6), (15, 8)] { let circuit = build_repetition_code(num_data, num_rounds); - let tracked_op_qubits: Vec = (0..num_data).collect(); + let tracked_pauli_qubits: Vec = (0..num_data).collect(); let name = format!("rep_d{num_data}r{num_rounds}"); let result = benchmark_circuit( &name, &circuit, - &tracked_op_qubits, + &tracked_pauli_qubits, num_shots, p_error, seed, @@ -318,7 +318,7 @@ fn main() { println!("\nTest 2: Fixed Circuit (rep_d7r4) - Varying Shots\n"); let circuit = build_repetition_code(7, 4); - let tracked_op_qubits: Vec = (0..7).collect(); + let tracked_pauli_qubits: Vec = (0..7).collect(); let mut shot_results = Vec::new(); @@ -327,7 +327,7 @@ fn main() { let result = benchmark_circuit( &name, &circuit, - &tracked_op_qubits, + &tracked_pauli_qubits, num_shots, p_error, seed, @@ -348,13 +348,13 @@ fn main() { for (distance, rounds) in [(3, 2), (4, 2), (5, 3), (6, 3), (7, 4)] { let circuit = build_surface_code_grid(distance, rounds); let num_data = distance * distance; - let tracked_op_qubits: Vec = (0..num_data).collect(); + let tracked_pauli_qubits: Vec = (0..num_data).collect(); let name = format!("surf_d{distance}r{rounds}"); let result = benchmark_circuit( &name, &circuit, - &tracked_op_qubits, + &tracked_pauli_qubits, num_shots, p_error, seed, diff --git a/crates/pecos-gpu-sims/examples/profile_samplers.rs b/crates/pecos-gpu-sims/examples/profile_samplers.rs index ace061419..cefa9cd37 100644 --- a/crates/pecos-gpu-sims/examples/profile_samplers.rs +++ b/crates/pecos-gpu-sims/examples/profile_samplers.rs @@ -512,8 +512,8 @@ fn main() { let num_data = distance * distance; // Build influence map - let tracked_op_qubits: Vec = (0..num_data).collect(); - let builder = InfluenceBuilder::new(&circuit).with_z(&tracked_op_qubits); + let tracked_pauli_qubits: Vec = (0..num_data).collect(); + let builder = InfluenceBuilder::new(&circuit).with_z(&tracked_pauli_qubits); let influence_map = builder.build(); let num_locations = influence_map.locations.len(); diff --git a/crates/pecos-gpu-sims/src/gpu_pauli_prop.rs b/crates/pecos-gpu-sims/src/gpu_pauli_prop.rs index 1c88807da..d353873b9 100644 --- a/crates/pecos-gpu-sims/src/gpu_pauli_prop.rs +++ b/crates/pecos-gpu-sims/src/gpu_pauli_prop.rs @@ -652,7 +652,7 @@ impl GpuPauliProp { /// Check if a Pauli string anticommutes with the accumulated faults. /// /// This is used to check whether faults flip a tracked Pauli string: - /// an odd number of anticommutations means the tracked operator flips. + /// an odd number of anticommutations means the tracked Pauli flips. /// /// # Arguments /// * `x_qubits` - Qubits with X in the Pauli string @@ -674,7 +674,7 @@ impl GpuPauliProp { let mut anticom_count = 0u32; - // X in the tracked operator anticommutes with Z faults. + // X in the tracked Pauli anticommutes with Z faults. for &q in x_qubits { let base = q * self.shot_words as usize; if (z_faults[base + word_idx] >> bit_idx) & 1 != 0 { @@ -682,7 +682,7 @@ impl GpuPauliProp { } } - // Z in the tracked operator anticommutes with X faults. + // Z in the tracked Pauli anticommutes with X faults. for &q in z_qubits { let base = q * self.shot_words as usize; if (x_faults[base + word_idx] >> bit_idx) & 1 != 0 { diff --git a/crates/pecos-hugr/src/engine/control_flow/cfg.rs b/crates/pecos-hugr/src/engine/control_flow/cfg.rs index b05553754..b0930ee2c 100644 --- a/crates/pecos-hugr/src/engine/control_flow/cfg.rs +++ b/crates/pecos-hugr/src/engine/control_flow/cfg.rs @@ -320,10 +320,10 @@ impl HugrEngine { // Check the current block if let Some(block_info) = cfg_info.blocks.get(&active_cfg.current_block) { - // Check if this block has tracked ops that drive completion - // Quantum, calls, conditionals, bool, extension, and tailloops are tracked - // Classical_ops are not tracked (they complete when their inputs are ready) - let has_tracked_ops = !block_info.quantum_ops.is_empty() + // Check if this block has operations that drive completion. + // Quantum, calls, conditionals, bool, extension, and tailloops + // complete explicitly. Classical_ops complete when their inputs are ready. + let has_completion_driving_ops = !block_info.quantum_ops.is_empty() || !block_info.call_nodes.is_empty() || !block_info.conditional_nodes.is_empty() || !block_info.bool_ops.is_empty() @@ -331,7 +331,7 @@ impl HugrEngine { || !block_info.tailloop_nodes.is_empty(); // Check if the processed node is in this block - let is_in_block = if has_tracked_ops { + let is_in_block = if has_completion_driving_ops { block_info.quantum_ops.contains(&processed_node) || block_info.call_nodes.contains(&processed_node) || block_info.conditional_nodes.contains(&processed_node) @@ -345,8 +345,8 @@ impl HugrEngine { if is_in_block { // Check completion based on block type - let block_complete = if has_tracked_ops { - // Block with tracked ops: wait for all tracked op types + let block_complete = if has_completion_driving_ops { + // Block with completion-driving ops: wait for all such op types. let all_quantum_done = block_info .quantum_ops .iter() diff --git a/crates/pecos-qasm/src/engine.rs b/crates/pecos-qasm/src/engine.rs index 9a2ccba2a..f795d1b41 100644 --- a/crates/pecos-qasm/src/engine.rs +++ b/crates/pecos-qasm/src/engine.rs @@ -624,7 +624,7 @@ impl QASMEngine { | GateType::MeasCrosstalkGlobalPayload | GateType::QFree | GateType::Custom - | GateType::PauliOperatorMeta => Ok(()), // No-op gates + | GateType::TrackedPauliMeta => Ok(()), // No-op gates GateType::X | GateType::Z | GateType::Y diff --git a/crates/pecos-qec/src/fault_tolerance.rs b/crates/pecos-qec/src/fault_tolerance.rs index e802aff84..8aa05b7a7 100644 --- a/crates/pecos-qec/src/fault_tolerance.rs +++ b/crates/pecos-qec/src/fault_tolerance.rs @@ -58,7 +58,7 @@ pub use pauli_prop_checker::{ pub use propagator::{ DagFaultAnalyzer, DagFaultInfluenceMap, DagPropagator, DagSpacetimeLocation, DemOutputKind, DemOutputMetadata, DetectorId, Direction, FaultInfluence, FaultInfluenceMap, - InfluenceBasedChecker, MeasurementId, TickFaultAnalyzer, TrackedOpId, apply_gate, + InfluenceBasedChecker, MeasurementId, TickFaultAnalyzer, TrackedPauliId, apply_gate, propagate_backward_from_node, propagate_backward_from_tick, propagate_fault_backward, propagate_observable_backward, propagate_sparse_dag, propagate_through_circuit, propagate_through_dag, propagate_tick_range, diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs index 9c36b0c16..ae792f1b1 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/builder.rs @@ -356,7 +356,7 @@ impl<'a> DemBuilder<'a> { /// Parses and sets observable definitions from JSON. /// - /// Tracked operators are carried by the influence map; this helper is only + /// Tracked Paulis are carried by the influence map; this helper is only /// for observable metadata. /// /// Each object accepts either `"id"` or `"observable_id"` as the identifier key. @@ -410,7 +410,7 @@ impl<'a> DemBuilder<'a> { // Add non-detector outputs carried directly by the influence map. // Metadata-bearing outputs use separate compact ID spaces for standard - // observables and PECOS tracked operators. + // observables and PECOS tracked Paulis. if self.influence_map.dem_output_metadata.is_empty() { for dem_output_idx in 0..num_influence_dem_outputs { #[allow(clippy::cast_possible_truncation)] // DEM output count fits in u32 @@ -424,9 +424,9 @@ impl<'a> DemBuilder<'a> { let internal_id = internal_idx as u32; if let Some(dem_output_id) = self .influence_map - .tracked_op_id_for_internal_dem_output(internal_id) + .tracked_pauli_id_for_internal_dem_output(internal_id) { - dem.add_tracked_operator(DemOutput::from_metadata(dem_output_id, metadata)); + dem.add_tracked_pauli(DemOutput::from_metadata(dem_output_id, metadata)); } else if let Some(dem_output_id) = self .influence_map .observable_id_for_internal_dem_output(internal_id) @@ -437,7 +437,7 @@ impl<'a> DemBuilder<'a> { } // Add observable definitions in the standard `L` namespace. - // Observable IDs are not shifted by tracked operators. + // Observable IDs are not shifted by tracked Paulis. for obs in &self.observables { let def = DemOutput::new(obs.id).with_records(obs.records.iter().copied()); dem.add_observable(def); @@ -937,7 +937,7 @@ impl<'a> DemBuilder<'a> { // Convert to pre-defined detector IDs using XOR let mut triggered_dets: SmallVec<[u32; 4]> = SmallVec::new(); let mut triggered_obs: SmallVec<[u32; 2]> = SmallVec::new(); - let mut triggered_tracked_ops: SmallVec<[u32; 2]> = SmallVec::new(); + let mut triggered_tracked_paulis: SmallVec<[u32; 2]> = SmallVec::new(); for dem_output_idx in self .influence_map @@ -945,11 +945,11 @@ impl<'a> DemBuilder<'a> { { xor_toggle_2(&mut triggered_obs, dem_output_idx); } - for tracked_op_idx in self + for tracked_pauli_idx in self .influence_map - .get_tracked_op_indices(loc_idx, pauli.as_u8()) + .get_tracked_pauli_indices(loc_idx, pauli.as_u8()) { - xor_toggle_2(&mut triggered_tracked_ops, tracked_op_idx); + xor_toggle_2(&mut triggered_tracked_paulis, tracked_pauli_idx); } for &rust_det in rust_dets { @@ -973,12 +973,12 @@ impl<'a> DemBuilder<'a> { // Sort for canonical form triggered_dets.sort_unstable(); triggered_obs.sort_unstable(); - triggered_tracked_ops.sort_unstable(); + triggered_tracked_paulis.sort_unstable(); - FaultMechanism::from_sorted_with_tracked_ops( + FaultMechanism::from_sorted_with_tracked_paulis( triggered_dets, triggered_obs, - triggered_tracked_ops, + triggered_tracked_paulis, ) } } @@ -1411,44 +1411,48 @@ mod tests { use super::*; #[test] - fn test_from_circuit_tracks_tracked_operator() { + fn test_from_circuit_tracks_tracked_pauli() { use pecos_core::pauli::X; use pecos_quantum::DagCircuit; let mut circuit = DagCircuit::new(); circuit.pz(&[0]); circuit.h(&[0]); - circuit.tracked_operator_labeled("x_check", X(0)); + circuit.tracked_pauli_labeled("x_check", X(0)); let dem = DemBuilder::from_circuit(&circuit, 0.03, 0.0, 0.0, 0.0); assert_eq!(dem.num_dem_outputs(), 0); - assert_eq!(dem.num_tracked_ops(), 1); + assert_eq!(dem.num_tracked_paulis(), 1); assert_eq!(dem.num_observables(), 0); assert_eq!( - dem.tracked_ops()[0].kind, - Some(crate::fault_tolerance::DemOutputKind::TrackedOperator) + dem.tracked_paulis()[0].kind, + Some(crate::fault_tolerance::DemOutputKind::TrackedPauli) ); - assert_eq!(dem.tracked_ops()[0].label.as_deref(), Some("x_check")); + assert_eq!(dem.tracked_paulis()[0].label.as_deref(), Some("x_check")); assert_eq!( - dem.tracked_ops()[0].pauli.as_ref().unwrap().to_sparse_str(), + dem.tracked_paulis()[0] + .pauli + .as_ref() + .unwrap() + .to_sparse_str(), "+X0" ); assert!(!dem.to_string().contains("logical_observable")); assert!(!dem.to_string().contains("TP0")); let pecos_text = dem.to_pecos_string(); assert!(pecos_text.contains("TP0")); - assert!(pecos_text.contains("pecos_tracked_op")); + assert!(pecos_text.contains("pecos_tracked_pauli")); } #[test] - fn test_tracked_operator_and_observable_use_distinct_tracked_ops() { + fn test_tracked_pauli_and_observable_use_distinct_tracked_paulis() { use pecos_core::pauli::Z; use pecos_quantum::{Attribute, DagCircuit}; let mut circuit = DagCircuit::new(); circuit.pz(&[0]); - circuit.tracked_operator_labeled("z_check", Z(0)); + circuit.tracked_pauli_labeled("z_check", Z(0)); circuit.mz(&[0]); circuit.set_attr("num_measurements", Attribute::String("1".to_string())); circuit.set_attr( @@ -1459,20 +1463,20 @@ mod tests { let dem = DemBuilder::from_circuit(&circuit, 0.0, 0.0, 0.02, 0.03); assert_eq!(dem.num_dem_outputs(), 1); - assert_eq!(dem.num_tracked_ops(), 1); + assert_eq!(dem.num_tracked_paulis(), 1); assert_eq!(dem.num_observables(), 1); assert_eq!( dem.dem_outputs()[0].kind, Some(crate::fault_tolerance::DemOutputKind::Observable) ); - assert_eq!(dem.tracked_ops()[0].label.as_deref(), Some("z_check")); + assert_eq!(dem.tracked_paulis()[0].label.as_deref(), Some("z_check")); let dem_str = dem.to_string(); assert!(dem_str.contains("logical_observable L0")); assert!(!dem_str.contains("logical_observable L1")); assert!(!dem_str.contains("TP0")); let pecos_text = dem.to_pecos_string(); assert!(pecos_text.contains("TP0")); - assert!(pecos_text.contains("pecos_tracked_op")); + assert!(pecos_text.contains("pecos_tracked_pauli")); let summaries = dem.contribution_effect_summaries(); assert!( summaries @@ -1483,20 +1487,20 @@ mod tests { assert!( summaries .iter() - .any(|summary| summary.effect.tracked_ops.as_slice() == [0]), - "tracked operator should remain TP0" + .any(|summary| summary.effect.tracked_paulis.as_slice() == [0]), + "tracked Pauli should remain TP0" ); } #[test] - fn test_tick_dag_tick_dem_keeps_detector_observable_and_tracked_operator_distinct() { + fn test_tick_dag_tick_dem_keeps_detector_observable_and_tracked_pauli_distinct() { use pecos_core::pauli::X; use pecos_quantum::{DagCircuit, TickCircuit}; let mut circuit = TickCircuit::new(); circuit.tick().pz(&[0, 1]); circuit.tick().h(&[0]); - circuit.tracked_operator_labeled("tracked_x0", X(0)); + circuit.tracked_pauli_labeled("tracked_x0", X(0)); circuit.tick().mz(&[0, 1]); circuit.set_meta( "num_measurements", @@ -1515,22 +1519,26 @@ mod tests { assert_eq!(dem.num_observables(), 1); assert_eq!(dem.num_dem_outputs(), 1); assert_eq!(dem.dem_outputs()[0].id, 0); - assert_eq!(dem.num_tracked_ops(), 1); - assert_eq!(dem.tracked_ops()[0].id, 0); - assert_eq!(dem.tracked_ops()[0].label.as_deref(), Some("tracked_x0")); + assert_eq!(dem.num_tracked_paulis(), 1); + assert_eq!(dem.tracked_paulis()[0].id, 0); + assert_eq!(dem.tracked_paulis()[0].label.as_deref(), Some("tracked_x0")); assert_eq!( - dem.tracked_ops()[0].pauli.as_ref().unwrap().to_sparse_str(), + dem.tracked_paulis()[0] + .pauli + .as_ref() + .unwrap() + .to_sparse_str(), "+X0" ); let standard_text = dem.to_string(); assert!(standard_text.contains("logical_observable L0")); assert!(!standard_text.contains("logical_observable L1")); - assert!(!standard_text.contains("pecos_tracked_op")); + assert!(!standard_text.contains("pecos_tracked_pauli")); let pecos_text = dem.to_pecos_string(); assert!(pecos_text.contains("pecos_observable")); - assert!(pecos_text.contains("pecos_tracked_op")); + assert!(pecos_text.contains("pecos_tracked_pauli")); let summaries = dem.contribution_effect_summaries(); assert!( @@ -1931,7 +1939,7 @@ mod tests { assert_eq!(dem.num_dem_outputs(), 1); assert_eq!(dem.num_observables(), 1); - assert_eq!(dem.num_tracked_ops(), 0); + assert_eq!(dem.num_tracked_paulis(), 0); assert_eq!(dem.dem_outputs()[0].records.as_slice(), &[-1, -3]); } diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs index 7304ba6de..7ba0febe2 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/dem_sampler.rs @@ -250,7 +250,7 @@ impl SamplingEngine { /// Number of observables represented by `L` columns. /// - /// When no PECOS tracked-operator metadata is present, every `L` output + /// When no PECOS tracked-Pauli metadata is present, every `L` output /// is treated as an observable. #[must_use] pub fn num_observables(&self) -> usize { @@ -647,7 +647,7 @@ impl SamplingEngine { /// The sampler still reports per-DEM-output flip counts for every `L` /// output. `logical_error_count` and `undetectable_count` are computed /// from the selected observable outputs only, so unmeasured tracked - /// operators do not affect decoder-style observable statistics. + /// Paulis do not affect decoder-style observable statistics. #[must_use] pub fn sample_statistics_for_observable_indices( &self, @@ -1675,8 +1675,8 @@ impl SamplingEngine { stats.per_dem_output[obs_idx] = count; } - // Aggregate logical-error mask from observables only. Tracked - // operators remain in per_dem_output but do not define decoder failures. + // Aggregate logical-error mask from observables only. Tracked Paulis + // remain in per_dem_output but do not define decoder failures. let mut observable_words = vec![0u64; num_words]; for &obs_idx in observable_indices { if let Some(col) = dem_output_words.get(obs_idx) { @@ -3194,7 +3194,7 @@ mod tests { } #[test] - fn test_from_mechanisms_with_tracked_ops() { + fn test_from_mechanisms_with_tracked_paulis() { // Mechanism that flips D0 and L0 let mechanisms = vec![(0.1, vec![0u32], vec![0u32])]; let sampler = SamplingEngine::from_mechanisms(mechanisms, 1, 1); diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs index b84f7c826..d18e60b01 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/equivalence.rs @@ -86,7 +86,7 @@ impl ParsedMechanism { components: vec![MechanismComponent { detectors, observables, - tracked_ops: Vec::new(), + tracked_paulis: Vec::new(), }], } } @@ -102,7 +102,7 @@ impl ParsedMechanism { pub fn combined_effect(&self) -> (Vec, Vec, Vec) { let mut all_dets: BTreeSet = BTreeSet::new(); let mut all_obs: BTreeSet = BTreeSet::new(); - let mut all_tracked_ops: BTreeSet = BTreeSet::new(); + let mut all_tracked_paulis: BTreeSet = BTreeSet::new(); for comp in &self.components { for &d in &comp.detectors { @@ -119,11 +119,11 @@ impl ParsedMechanism { all_obs.insert(o); } } - for &op in &comp.tracked_ops { - if all_tracked_ops.contains(&op) { - all_tracked_ops.remove(&op); + for &op in &comp.tracked_paulis { + if all_tracked_paulis.contains(&op) { + all_tracked_paulis.remove(&op); } else { - all_tracked_ops.insert(op); + all_tracked_paulis.insert(op); } } } @@ -131,18 +131,18 @@ impl ParsedMechanism { // BTreeSet is already sorted, so just collect let dets: Vec = all_dets.into_iter().collect(); let obs: Vec = all_obs.into_iter().collect(); - let tracked_ops: Vec = all_tracked_ops.into_iter().collect(); - (dets, obs, tracked_ops) + let tracked_paulis: Vec = all_tracked_paulis.into_iter().collect(); + (dets, obs, tracked_paulis) } /// Creates an effect key for this mechanism (for aggregation). #[must_use] pub fn effect_key(&self) -> EffectKey { - let (dets, obs, tracked_ops) = self.combined_effect(); + let (dets, obs, tracked_paulis) = self.combined_effect(); EffectKey { detectors: dets, observables: obs, - tracked_ops, + tracked_paulis, } } @@ -160,7 +160,7 @@ impl ParsedMechanism { for &o in &comp.observables { tokens.push(format!("L{o}")); } - for &op in &comp.tracked_ops { + for &op in &comp.tracked_paulis { tokens.push(format!("TP{op}")); } tokens.join(" ") @@ -177,8 +177,8 @@ pub struct MechanismComponent { pub detectors: Vec, /// Observable IDs in this component. pub observables: Vec, - /// PECOS tracked-Pauli operator IDs in this component. - pub tracked_ops: Vec, + /// PECOS tracked-Pauli IDs in this component. + pub tracked_paulis: Vec, } /// Key for aggregating mechanisms by their effect. @@ -188,8 +188,8 @@ pub struct EffectKey { pub detectors: Vec, /// Sorted observable IDs. pub observables: Vec, - /// Sorted tracked-Pauli operator IDs. - pub tracked_ops: Vec, + /// Sorted tracked-Pauli IDs. + pub tracked_paulis: Vec, } impl EffectKey { @@ -201,7 +201,7 @@ impl EffectKey { Self { detectors, observables, - tracked_ops: Vec::new(), + tracked_paulis: Vec::new(), } } } @@ -215,7 +215,7 @@ impl fmt::Display for EffectKey { for &o in &self.observables { parts.push(format!("L{o}")); } - for &op in &self.tracked_ops { + for &op in &self.tracked_paulis { parts.push(format!("TP{op}")); } if parts.is_empty() { @@ -241,8 +241,8 @@ pub struct ParsedDem { pub num_dem_outputs: u32, /// PECOS metadata for `L` observables, indexed by `L`. pub dem_outputs: Vec>, - /// PECOS metadata for tracked operators in their own ID space. - pub tracked_ops: Vec>, + /// PECOS metadata for tracked Paulis in their own ID space. + pub tracked_paulis: Vec>, } impl ParsedDem { @@ -254,7 +254,7 @@ impl ParsedDem { num_detectors: 0, num_dem_outputs: 0, dem_outputs: Vec::new(), - tracked_ops: Vec::new(), + tracked_paulis: Vec::new(), } } @@ -281,10 +281,10 @@ impl ParsedDem { self.num_dem_outputs } - /// Number of tracked operators. + /// Number of tracked Paulis. #[must_use] - pub fn num_tracked_ops(&self) -> u32 { - u32::try_from(self.tracked_ops.len()).unwrap_or(u32::MAX) + pub fn num_tracked_paulis(&self) -> u32 { + u32::try_from(self.tracked_paulis.len()).unwrap_or(u32::MAX) } fn record_metadata(ops: &mut Vec>, op: DemOutput) { @@ -339,7 +339,7 @@ impl ParsedDem { fn parse_component(s: &str) -> Result { let mut detectors = Vec::new(); let mut observables = Vec::new(); - let mut tracked_ops = Vec::new(); + let mut tracked_paulis = Vec::new(); for token in s.split_whitespace() { if let Some(id_str) = token.strip_prefix('D') { @@ -355,8 +355,8 @@ impl ParsedDem { } else if let Some(id_str) = token.strip_prefix("TP") { let id: u32 = id_str .parse() - .map_err(|_| DemParseError::InvalidTrackedOpId(token.to_string()))?; - tracked_ops.push(id); + .map_err(|_| DemParseError::InvalidTrackedPauliId(token.to_string()))?; + tracked_paulis.push(id); } else { return Err(DemParseError::InvalidTarget(token.to_string())); } @@ -364,12 +364,12 @@ impl ParsedDem { detectors.sort_unstable(); observables.sort_unstable(); - tracked_ops.sort_unstable(); + tracked_paulis.sort_unstable(); Ok(MechanismComponent { detectors, observables, - tracked_ops, + tracked_paulis, }) } @@ -406,8 +406,8 @@ impl ParsedDem { // For decomposed mechanisms, each component fires independently for comp in &mech.components { let mut key = EffectKey::new(comp.detectors.clone(), comp.observables.clone()); - key.tracked_ops.clone_from(&comp.tracked_ops); - key.tracked_ops.sort_unstable(); + key.tracked_paulis.clone_from(&comp.tracked_paulis); + key.tracked_paulis.sort_unstable(); aggregated .entry(key) .and_modify(|p| *p = combine_probabilities(*p, mech.probability)) @@ -503,7 +503,7 @@ impl ParsedDem { // Use combined_effect() to get the union of all detectors/observables // since all components fire together when the error occurs let mechanisms = self.mechanisms.iter().map(|mech| { - let (dets, obs, _tracked_ops) = mech.combined_effect(); + let (dets, obs, _tracked_paulis) = mech.combined_effect(); (mech.probability, dets, obs) }); @@ -529,18 +529,18 @@ impl ParsedDem { }) }) .collect(); - let tracked_ops = self - .tracked_ops + let tracked_paulis = self + .tracked_paulis .iter() .enumerate() .map(|(id, output)| { output.clone().or_else(|| { #[allow(clippy::cast_possible_truncation)] - // parsed tracked-op count fits in u32 + // parsed tracked-Pauli count fits in u32 { Some( DemOutput::new(id as u32) - .with_kind(crate::fault_tolerance::DemOutputKind::TrackedOperator), + .with_kind(crate::fault_tolerance::DemOutputKind::TrackedPauli), ) } }) @@ -548,7 +548,7 @@ impl ParsedDem { .collect(); super::sampler::DemSampler::from_engine(engine) - .with_dem_output_metadata(dem_outputs, tracked_ops) + .with_dem_output_metadata(dem_outputs, tracked_paulis) } /// Convert to a decomposed (graphlike) DEM string. @@ -633,9 +633,9 @@ impl FromStr for ParsedDem { let mut mechanisms = Vec::new(); let mut max_det: i32 = -1; let mut max_obs: i32 = -1; - let mut max_tracked_op: i32 = -1; + let mut max_tracked_pauli: i32 = -1; let mut dem_outputs: Vec> = Vec::new(); - let mut tracked_ops: Vec> = Vec::new(); + let mut tracked_paulis: Vec> = Vec::new(); for line in dem_str.lines() { let line = line.trim(); @@ -663,10 +663,10 @@ impl FromStr for ParsedDem { max_obs = max_obs.max(o as i32); } } - for &op in &comp.tracked_ops { - #[allow(clippy::cast_possible_wrap)] // tracked-op ID fits in i32 + for &op in &comp.tracked_paulis { + #[allow(clippy::cast_possible_wrap)] // tracked-Pauli ID fits in i32 { - max_tracked_op = max_tracked_op.max(op as i32); + max_tracked_pauli = max_tracked_pauli.max(op as i32); } } } @@ -696,15 +696,17 @@ impl FromStr for ParsedDem { ); } // Parse PECOS DEM-superset metadata declarations. - else if line.starts_with("pecos_observable") || line.starts_with("pecos_tracked_op") { + else if line.starts_with("pecos_observable") + || line.starts_with("pecos_tracked_pauli") + { let op = parse_pecos_dem_metadata_line(line) .map_err(|err| DemParseError::InvalidPecosMetadata(err.to_string()))?; - if op.is_tracked_operator() { - #[allow(clippy::cast_possible_wrap)] // tracked-op ID fits in i32 + if op.is_tracked_pauli() { + #[allow(clippy::cast_possible_wrap)] // tracked-Pauli ID fits in i32 { - max_tracked_op = max_tracked_op.max(op.id as i32); + max_tracked_pauli = max_tracked_pauli.max(op.id as i32); } - Self::record_metadata(&mut tracked_ops, op); + Self::record_metadata(&mut tracked_paulis, op); } else { #[allow(clippy::cast_possible_wrap)] // observable ID fits in i32 { @@ -729,10 +731,10 @@ impl FromStr for ParsedDem { dem_outputs.resize(max_obs as usize + 1, None); } } - if max_tracked_op >= 0 { + if max_tracked_pauli >= 0 { #[allow(clippy::cast_sign_loss)] // guarded by >= 0 check { - tracked_ops.resize(max_tracked_op as usize + 1, None); + tracked_paulis.resize(max_tracked_pauli as usize + 1, None); } } @@ -755,7 +757,7 @@ impl FromStr for ParsedDem { 0 }, dem_outputs, - tracked_ops, + tracked_paulis, }) } } @@ -775,8 +777,8 @@ pub enum DemParseError { InvalidDetectorId(String), /// Invalid observable ID. InvalidObservableId(String), - /// Invalid tracked-Pauli operator ID. - InvalidTrackedOpId(String), + /// Invalid tracked-Pauli ID. + InvalidTrackedPauliId(String), /// Invalid target token in an error line. InvalidTarget(String), /// Invalid PECOS DEM-superset metadata. @@ -790,7 +792,7 @@ impl std::fmt::Display for DemParseError { Self::InvalidProbability(s) => write!(f, "Invalid probability: {s}"), Self::InvalidDetectorId(s) => write!(f, "Invalid detector ID: {s}"), Self::InvalidObservableId(s) => write!(f, "Invalid observable ID: {s}"), - Self::InvalidTrackedOpId(s) => write!(f, "Invalid tracked Pauli ID: {s}"), + Self::InvalidTrackedPauliId(s) => write!(f, "Invalid tracked Pauli ID: {s}"), Self::InvalidTarget(s) => write!(f, "Invalid DEM error target: {s}"), Self::InvalidPecosMetadata(s) => write!(f, "Invalid PECOS DEM metadata: {s}"), } @@ -1259,7 +1261,7 @@ mod tests { fn test_parse_accepts_pecos_dem_superset_metadata() { let dem_str = r#" error(0.02) D0 TP0 - pecos_tracked_op {"id":0,"kind":"tracked_operator","label":"track","pauli":"+X0 Z2","records":[]} + pecos_tracked_pauli {"id":0,"kind":"tracked_pauli","label":"track","pauli":"+X0 Z2","records":[]} "#; let dem = ParsedDem::from_str(dem_str).unwrap(); @@ -1267,22 +1269,22 @@ mod tests { assert_eq!(dem.num_detectors, 1); assert_eq!(dem.num_dem_outputs(), 0); assert_eq!(dem.num_observables(), 0); - assert_eq!(dem.num_tracked_ops(), 1); - assert_eq!(dem.mechanisms[0].components[0].tracked_ops, vec![0]); + assert_eq!(dem.num_tracked_paulis(), 1); + assert_eq!(dem.mechanisms[0].components[0].tracked_paulis, vec![0]); assert_eq!(dem.mechanisms[0].format_targets(), "D0 TP0"); assert_eq!(dem.mechanisms[0].effect_key().to_string(), "D0 TP0"); - let op = dem.tracked_ops[0].as_ref().unwrap(); + let op = dem.tracked_paulis[0].as_ref().unwrap(); assert_eq!(op.label.as_deref(), Some("track")); assert_eq!( op.kind, - Some(crate::fault_tolerance::DemOutputKind::TrackedOperator) + Some(crate::fault_tolerance::DemOutputKind::TrackedPauli) ); assert_eq!(op.pauli.as_ref().unwrap().to_sparse_str(), "+X0 Z2"); } #[test] fn test_parse_rejects_malformed_pecos_dem_superset_metadata() { - let err = ParsedDem::from_str("pecos_tracked_op not-json").unwrap_err(); + let err = ParsedDem::from_str("pecos_tracked_pauli not-json").unwrap_err(); assert!(matches!(err, DemParseError::InvalidPecosMetadata(_))); } @@ -1292,39 +1294,39 @@ mod tests { assert_eq!(dem.num_detectors, 2); assert_eq!(dem.num_dem_outputs(), 1); - assert_eq!(dem.num_tracked_ops(), 3); + assert_eq!(dem.num_tracked_paulis(), 3); assert_eq!(dem.mechanisms[0].components[0].detectors, vec![1]); assert_eq!(dem.mechanisms[0].components[0].observables, vec![0]); - assert_eq!(dem.mechanisms[0].components[0].tracked_ops, vec![2]); + assert_eq!(dem.mechanisms[0].components[0].tracked_paulis, vec![2]); assert_eq!(dem.mechanisms[0].effect_key().to_string(), "D1 L0 TP2"); } #[test] fn test_decomposed_tracked_pauli_targets_xor_by_parity() { let cancels = ParsedDem::from_str("error(0.5) TP0 ^ TP0").unwrap(); - let (dets, obs, tracked_ops) = cancels.mechanisms[0].combined_effect(); + let (dets, obs, tracked_paulis) = cancels.mechanisms[0].combined_effect(); assert!(dets.is_empty()); assert!(obs.is_empty()); - assert!(tracked_ops.is_empty()); + assert!(tracked_paulis.is_empty()); assert_eq!(cancels.mechanisms[0].effect_key().to_string(), "(empty)"); let leaves_detector = ParsedDem::from_str("error(0.5) D0 TP0 ^ TP0").unwrap(); - let (dets, obs, tracked_ops) = leaves_detector.mechanisms[0].combined_effect(); + let (dets, obs, tracked_paulis) = leaves_detector.mechanisms[0].combined_effect(); assert_eq!(dets, vec![0]); assert!(obs.is_empty()); - assert!(tracked_ops.is_empty()); + assert!(tracked_paulis.is_empty()); assert_eq!(leaves_detector.mechanisms[0].effect_key().to_string(), "D0"); } #[test] fn test_duplicate_tracked_pauli_targets_cancel_by_parity() { let dem = ParsedDem::from_str("error(0.1) TP0 TP0").unwrap(); - assert_eq!(dem.mechanisms[0].components[0].tracked_ops, vec![0, 0]); + assert_eq!(dem.mechanisms[0].components[0].tracked_paulis, vec![0, 0]); - let (dets, obs, tracked_ops) = dem.mechanisms[0].combined_effect(); + let (dets, obs, tracked_paulis) = dem.mechanisms[0].combined_effect(); assert!(dets.is_empty()); assert!(obs.is_empty()); - assert!(tracked_ops.is_empty()); + assert!(tracked_paulis.is_empty()); assert_eq!(dem.mechanisms[0].effect_key().to_string(), "(empty)"); } @@ -1340,7 +1342,7 @@ mod tests { for target in ["TP", "TPx", "TP-1"] { let err = ParsedDem::from_str(&format!("error(0.125) {target}")).unwrap_err(); assert!( - matches!(err, DemParseError::InvalidTrackedOpId(_)), + matches!(err, DemParseError::InvalidTrackedPauliId(_)), "{target} should be rejected as a malformed tracked-Pauli target" ); } @@ -1352,20 +1354,20 @@ mod tests { let sampler = dem.to_dem_sampler(); let mut rng = PecosRng::seed_from_u64(123); - assert_eq!(dem.num_tracked_ops(), 1); + assert_eq!(dem.num_tracked_paulis(), 1); assert_eq!(sampler.num_detectors(), 0); assert_eq!(sampler.num_dem_outputs(), 0); - assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!(sampler.num_tracked_paulis(), 1); let (detectors, dem_outputs) = sampler.sample(&mut rng); assert!(detectors.is_empty()); assert!(dem_outputs.is_empty()); - let err = sampler.sample_tracked_operator_flips(&mut rng).unwrap_err(); + let err = sampler.sample_tracked_pauli_flips(&mut rng).unwrap_err(); assert_eq!(err.backend(), "DemSampler"); - assert_eq!(err.num_tracked_ops(), 1); + assert_eq!(err.num_tracked_paulis(), 1); } #[test] - fn test_parsed_dem_samplers_project_different_tracked_ops_the_same() { + fn test_parsed_dem_samplers_project_different_tracked_paulis_the_same() { let dem1 = ParsedDem::from_str("error(1.0) D0 TP0").unwrap(); let dem2 = ParsedDem::from_str("error(1.0) D0 TP1").unwrap(); let sampler1 = dem1.to_dem_sampler(); @@ -1377,8 +1379,8 @@ mod tests { assert_eq!(sampler2.num_detectors(), 1); assert_eq!(sampler1.num_dem_outputs(), 0); assert_eq!(sampler2.num_dem_outputs(), 0); - assert_eq!(sampler1.num_tracked_ops(), 1); - assert_eq!(sampler2.num_tracked_ops(), 2); + assert_eq!(sampler1.num_tracked_paulis(), 1); + assert_eq!(sampler2.num_tracked_paulis(), 2); assert_eq!(sampler1.sample(&mut rng1), sampler2.sample(&mut rng2)); } @@ -1515,10 +1517,10 @@ error(0.02) D1 D2 let dem = ParsedDem::from_str("error(0.5) D0 ^ D0").unwrap(); // The combined effect should be empty - let (dets, obs, tracked_ops) = dem.mechanisms[0].combined_effect(); + let (dets, obs, tracked_paulis) = dem.mechanisms[0].combined_effect(); assert!(dets.is_empty()); assert!(obs.is_empty()); - assert!(tracked_ops.is_empty()); + assert!(tracked_paulis.is_empty()); // Sample and verify D0 never fires let mut rng = PecosRng::seed_from_u64(42); diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs index 1dd24cf98..d564fbf49 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/sampler.rs @@ -98,47 +98,47 @@ impl std::fmt::Display for DetectorValidationError { impl std::error::Error for DetectorValidationError {} /// Error returned when a sampler backend is asked to directly evaluate tracked -/// operators it only preserves as metadata. +/// Paulis it only preserves as metadata. #[derive(Debug, Clone, PartialEq, Eq)] -pub struct TrackedOperatorSamplingError { +pub struct TrackedPauliSamplingError { backend: &'static str, - num_tracked_ops: usize, + num_tracked_paulis: usize, } -impl TrackedOperatorSamplingError { - fn new(backend: &'static str, num_tracked_ops: usize) -> Self { +impl TrackedPauliSamplingError { + fn new(backend: &'static str, num_tracked_paulis: usize) -> Self { Self { backend, - num_tracked_ops, + num_tracked_paulis, } } - /// Backend that rejected direct tracked-operator sampling. + /// Backend that rejected direct tracked-Pauli sampling. #[must_use] pub fn backend(&self) -> &'static str { self.backend } - /// Number of tracked operators carried as metadata by that backend. + /// Number of tracked Paulis carried as metadata by that backend. #[must_use] - pub fn num_tracked_ops(&self) -> usize { - self.num_tracked_ops + pub fn num_tracked_paulis(&self) -> usize { + self.num_tracked_paulis } } -impl std::fmt::Display for TrackedOperatorSamplingError { +impl std::fmt::Display for TrackedPauliSamplingError { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!( f, - "{} cannot directly sample tracked operator flips for {} tracked operator(s). \ + "{} cannot directly sample tracked Pauli flips for {} tracked Pauli(s). \ This backend samples decoder-facing detectors and observables only; tracked \ - operators are preserved as PECOS metadata and fault effects.", - self.backend, self.num_tracked_ops + Paulis are preserved as PECOS metadata and fault effects.", + self.backend, self.num_tracked_paulis ) } } -impl std::error::Error for TrackedOperatorSamplingError {} +impl std::error::Error for TrackedPauliSamplingError {} /// Output mode for the unified sampler. #[derive(Debug, Clone, Copy, PartialEq, Eq)] @@ -175,10 +175,10 @@ pub struct SamplerLabels { pub dem_output_labels: Vec>, /// Full PECOS metadata for standard DEM `L` observables. pub dem_outputs: Vec>, - /// Labels for PECOS tracked operators. - pub tracked_op_labels: Vec>, - /// Full PECOS metadata for tracked operators in their own ID space. - pub tracked_ops: Vec>, + /// Labels for PECOS tracked Paulis. + pub tracked_pauli_labels: Vec>, + /// Full PECOS metadata for tracked Paulis in their own ID space. + pub tracked_paulis: Vec>, /// Labels for dual-output detector channels. pub dual_detectors: Vec>, } @@ -222,16 +222,18 @@ fn dem_outputs_from_influence_map( targets } -fn tracked_ops_from_influence_map(influence_map: &DagFaultInfluenceMap) -> Vec> { - let mut tracked_ops = Vec::new(); +fn tracked_paulis_from_influence_map( + influence_map: &DagFaultInfluenceMap, +) -> Vec> { + let mut tracked_paulis = Vec::new(); for metadata in &influence_map.dem_output_metadata { - if metadata.kind == DemOutputKind::TrackedOperator { - #[allow(clippy::cast_possible_truncation)] // tracked-op count fits in u32 - let id = tracked_ops.len() as u32; - tracked_ops.push(Some(DemOutput::from_metadata(id, metadata))); + if metadata.kind == DemOutputKind::TrackedPauli { + #[allow(clippy::cast_possible_truncation)] // tracked-Pauli count fits in u32 + let id = tracked_paulis.len() as u32; + tracked_paulis.push(Some(DemOutput::from_metadata(id, metadata))); } } - tracked_ops + tracked_paulis } fn dem_outputs_from_records( @@ -268,7 +270,7 @@ fn dem_outputs_from_records( fn merge_dem_output_metadata( mut labels: SamplerLabels, targets: Vec>, - tracked_ops: Vec>, + tracked_paulis: Vec>, ) -> SamplerLabels { if labels.dem_outputs.len() < targets.len() { labels.dem_outputs.resize(targets.len(), None); @@ -289,24 +291,24 @@ fn merge_dem_output_metadata( } } - if labels.tracked_ops.len() < tracked_ops.len() { - labels.tracked_ops.resize(tracked_ops.len(), None); + if labels.tracked_paulis.len() < tracked_paulis.len() { + labels.tracked_paulis.resize(tracked_paulis.len(), None); } - for (idx, tracked_op) in tracked_ops.into_iter().enumerate() { - if labels.tracked_ops[idx].is_none() { - labels.tracked_ops[idx] = tracked_op; + for (idx, tracked_pauli) in tracked_paulis.into_iter().enumerate() { + if labels.tracked_paulis[idx].is_none() { + labels.tracked_paulis[idx] = tracked_pauli; } } - let tracked_op_labels = labels_from_dem_outputs(&labels.tracked_ops); - if labels.tracked_op_labels.len() < tracked_op_labels.len() { + let tracked_pauli_labels = labels_from_dem_outputs(&labels.tracked_paulis); + if labels.tracked_pauli_labels.len() < tracked_pauli_labels.len() { labels - .tracked_op_labels - .resize(tracked_op_labels.len(), None); + .tracked_pauli_labels + .resize(tracked_pauli_labels.len(), None); } - for (idx, label) in tracked_op_labels.into_iter().enumerate() { - if labels.tracked_op_labels[idx].is_none() { - labels.tracked_op_labels[idx] = label; + for (idx, label) in tracked_pauli_labels.into_iter().enumerate() { + if labels.tracked_pauli_labels[idx].is_none() { + labels.tracked_pauli_labels[idx] = label; } } @@ -505,7 +507,7 @@ impl DemSampler { } /// Build a detector-event sampler from a [`DetectorErrorModel`], preserving - /// PECOS metadata for observables and tracked operators. + /// PECOS metadata for observables and tracked Paulis. #[must_use] pub fn from_detector_error_model(dem: &super::types::DetectorErrorModel) -> Self { let (mechanisms, _coords) = dem.to_mechanisms(); @@ -514,26 +516,28 @@ impl DemSampler { let mut sampler = Self::from_engine(engine); sampler.labels.dem_outputs = dem_outputs_by_id(dem.dem_outputs(), dem.num_dem_outputs()); sampler.labels.dem_output_labels = labels_from_dem_outputs(&sampler.labels.dem_outputs); - sampler.labels.tracked_ops = dem_outputs_by_id(dem.tracked_ops(), dem.num_tracked_ops()); - sampler.labels.tracked_op_labels = labels_from_dem_outputs(&sampler.labels.tracked_ops); + sampler.labels.tracked_paulis = + dem_outputs_by_id(dem.tracked_paulis(), dem.num_tracked_paulis()); + sampler.labels.tracked_pauli_labels = + labels_from_dem_outputs(&sampler.labels.tracked_paulis); sampler } - /// Attach observable and tracked-operator metadata to an existing sampler. + /// Attach observable and tracked-Pauli metadata to an existing sampler. /// /// This is useful for parser paths where the sampling engine projects to /// detector/observable columns but the original PECOS DEM still declared - /// tracked operators in a separate ID space. + /// tracked Paulis in a separate ID space. #[must_use] pub fn with_dem_output_metadata( mut self, dem_outputs: Vec>, - tracked_ops: Vec>, + tracked_paulis: Vec>, ) -> Self { self.labels.dem_outputs = dem_outputs; self.labels.dem_output_labels = labels_from_dem_outputs(&self.labels.dem_outputs); - self.labels.tracked_ops = tracked_ops; - self.labels.tracked_op_labels = labels_from_dem_outputs(&self.labels.tracked_ops); + self.labels.tracked_paulis = tracked_paulis; + self.labels.tracked_pauli_labels = labels_from_dem_outputs(&self.labels.tracked_paulis); self } @@ -562,8 +566,8 @@ impl DemSampler { let mut labels = SamplerLabels::default(); labels.dem_outputs = dem_outputs_from_influence_map(influence_map, num_dem_outputs); labels.dem_output_labels = labels_from_dem_outputs(&labels.dem_outputs); - labels.tracked_ops = tracked_ops_from_influence_map(influence_map); - labels.tracked_op_labels = labels_from_dem_outputs(&labels.tracked_ops); + labels.tracked_paulis = tracked_paulis_from_influence_map(influence_map); + labels.tracked_pauli_labels = labels_from_dem_outputs(&labels.tracked_paulis); Self { inner, non_det_mask: Vec::new(), @@ -601,10 +605,10 @@ impl DemSampler { self.num_dem_outputs } - /// Number of tracked operators. + /// Number of tracked Paulis. #[must_use] - pub fn num_tracked_ops(&self) -> usize { - self.labels.tracked_ops.len() + pub fn num_tracked_paulis(&self) -> usize { + self.labels.tracked_paulis.len() } /// Standard observable `L` IDs selected from this sampler. @@ -613,67 +617,65 @@ impl DemSampler { (0..self.num_dem_outputs).collect() } - /// PECOS tracked-operator IDs selected from this sampler. + /// PECOS tracked-Pauli IDs selected from this sampler. /// - /// Decoder-facing DEM samplers do not directly evaluate tracked operators: - /// tracked operators are preserved in metadata and in PECOS DEM fault + /// Decoder-facing DEM samplers do not directly evaluate tracked Paulis: + /// tracked Paulis are preserved in metadata and in PECOS DEM fault /// effects, but the sampled bit columns are detectors plus standard /// observable `L` outputs only. /// /// # Errors /// - /// Returns [`TrackedOperatorSamplingError`] when tracked operators are - /// present and the caller is asking for a direct sampled tracked-operator + /// Returns [`TrackedPauliSamplingError`] when tracked Paulis are + /// present and the caller is asking for a direct sampled tracked-Pauli /// output space. - pub fn tracked_operator_ids(&self) -> Result, TrackedOperatorSamplingError> { - self.ensure_tracked_operator_sampling_supported()?; + pub fn tracked_pauli_ids(&self) -> Result, TrackedPauliSamplingError> { + self.ensure_tracked_pauli_sampling_supported()?; Ok(Vec::new()) } - /// Sample direct tracked-operator flips. + /// Sample direct tracked-Pauli flips. /// /// This returns an empty vector when the sampler carries no tracked - /// operators. If tracked operators are present, this backend fails + /// Paulis. If tracked Paulis are present, this backend fails /// explicitly instead of returning silently empty data. /// /// # Errors /// - /// Returns [`TrackedOperatorSamplingError`] when tracked operators are + /// Returns [`TrackedPauliSamplingError`] when tracked Paulis are /// present because [`DemSampler`] samples detector and observable columns, - /// not tracked-operator columns. - pub fn sample_tracked_operator_flips( + /// not tracked-Pauli columns. + pub fn sample_tracked_pauli_flips( &self, _rng: &mut R, - ) -> Result, TrackedOperatorSamplingError> { - self.ensure_tracked_operator_sampling_supported()?; + ) -> Result, TrackedPauliSamplingError> { + self.ensure_tracked_pauli_sampling_supported()?; Ok(Vec::new()) } - /// Sample direct tracked-operator flips for multiple shots. + /// Sample direct tracked-Pauli flips for multiple shots. /// /// # Errors /// - /// Returns [`TrackedOperatorSamplingError`] when tracked operators are - /// present for the same reason as [`Self::sample_tracked_operator_flips`]. - pub fn sample_tracked_operator_batch( + /// Returns [`TrackedPauliSamplingError`] when tracked Paulis are + /// present for the same reason as [`Self::sample_tracked_pauli_flips`]. + pub fn sample_tracked_pauli_batch( &self, num_shots: usize, _rng: &mut R, - ) -> Result>, TrackedOperatorSamplingError> { - self.ensure_tracked_operator_sampling_supported()?; + ) -> Result>, TrackedPauliSamplingError> { + self.ensure_tracked_pauli_sampling_supported()?; Ok(vec![Vec::new(); num_shots]) } - fn ensure_tracked_operator_sampling_supported( - &self, - ) -> Result<(), TrackedOperatorSamplingError> { - let num_tracked_ops = self.num_tracked_ops(); - if num_tracked_ops == 0 { + fn ensure_tracked_pauli_sampling_supported(&self) -> Result<(), TrackedPauliSamplingError> { + let num_tracked_paulis = self.num_tracked_paulis(); + if num_tracked_paulis == 0 { Ok(()) } else { - Err(TrackedOperatorSamplingError::new( + Err(TrackedPauliSamplingError::new( "DemSampler", - num_tracked_ops, + num_tracked_paulis, )) } } @@ -1062,14 +1064,14 @@ impl<'a> DemSamplerBuilder<'a> { self } - /// Extract detector, observable, and tracked-op definitions from a [`DagCircuit`]'s + /// Extract detector, observable, and tracked-Pauli definitions from a [`DagCircuit`]'s /// in-circuit annotations. /// /// Extract annotations from a [`DagCircuit`] and configure the sampler. /// /// Detector annotations are mapped to auto-detected detector indices. /// Observables are converted to measurement-record outputs. Tracked - /// operators remain unmeasured Pauli-operator annotations and are carried + /// Paulis remain unmeasured Pauli annotations and are carried /// through PECOS metadata only. #[must_use] pub fn with_circuit_annotations(mut self, circuit: &pecos_quantum::DagCircuit) -> Self { @@ -1166,14 +1168,14 @@ impl<'a> DemSamplerBuilder<'a> { self.labels.dem_output_labels = observable_labels; } - let tracked_op_labels: Vec> = circuit + let tracked_pauli_labels: Vec> = circuit .annotations() .iter() - .filter(|a| matches!(a.kind, AnnotationKind::TrackedOperator)) + .filter(|a| matches!(a.kind, AnnotationKind::TrackedPauli)) .map(|a| a.label.clone()) .collect(); - if !tracked_op_labels.is_empty() { - self.labels.tracked_op_labels = tracked_op_labels; + if !tracked_pauli_labels.is_empty() { + self.labels.tracked_pauli_labels = tracked_pauli_labels; } self @@ -1246,7 +1248,7 @@ impl<'a> DemSamplerBuilder<'a> { let num_dem_outputs = inner.num_dem_outputs(); let dem_outputs = dem_outputs_from_influence_map(self.influence_map, num_dem_outputs); - let tracked_ops = tracked_ops_from_influence_map(self.influence_map); + let tracked_paulis = tracked_paulis_from_influence_map(self.influence_map); DemSampler { inner, @@ -1255,7 +1257,7 @@ impl<'a> DemSamplerBuilder<'a> { mode: OutputMode::RawMeasurements, num_outputs: num_measurements, num_dem_outputs, - labels: merge_dem_output_metadata(self.labels, dem_outputs, tracked_ops), + labels: merge_dem_output_metadata(self.labels, dem_outputs, tracked_paulis), raw_remap: None, measurement_deps: Vec::new(), // No expansion needed (engine covers all measurements) } @@ -1337,7 +1339,7 @@ impl<'a> DemSamplerBuilder<'a> { let num_dem_outputs = inner.num_dem_outputs(); let dem_outputs = dem_outputs_from_records(self.influence_map, &observable_records, num_dem_outputs); - let tracked_ops = tracked_ops_from_influence_map(self.influence_map); + let tracked_paulis = tracked_paulis_from_influence_map(self.influence_map); Ok(DemSampler { inner, @@ -1346,7 +1348,7 @@ impl<'a> DemSamplerBuilder<'a> { mode: OutputMode::DetectorEvents, num_outputs: num_detectors, num_dem_outputs, - labels: merge_dem_output_metadata(self.labels, dem_outputs, tracked_ops), + labels: merge_dem_output_metadata(self.labels, dem_outputs, tracked_paulis), raw_remap: None, measurement_deps: Vec::new(), }) @@ -1668,7 +1670,7 @@ mod tests { assert_eq!(records_sampler.num_detectors(), 1); assert_eq!(records_sampler.num_dem_outputs(), 1); assert_eq!(records_sampler.num_observables(), 1); - assert_eq!(records_sampler.num_tracked_ops(), 0); + assert_eq!(records_sampler.num_tracked_paulis(), 0); assert_eq!(records_sampler.mode(), OutputMode::DetectorEvents); let json_sampler = DemSamplerBuilder::new(&im) @@ -1682,46 +1684,46 @@ mod tests { assert_eq!(json_sampler.num_detectors(), 1); assert_eq!(json_sampler.num_dem_outputs(), 1); assert_eq!(json_sampler.num_observables(), 1); - assert_eq!(json_sampler.num_tracked_ops(), 0); + assert_eq!(json_sampler.num_tracked_paulis(), 0); assert_eq!(json_sampler.mode(), OutputMode::DetectorEvents); } #[test] - fn from_circuit_preserves_tracked_operator_ops() { + fn from_circuit_preserves_tracked_paulis() { use crate::fault_tolerance::dem_builder::NoiseConfig; use pecos_core::pauli::X; let mut circuit = DagCircuit::new(); circuit.pz(&[0]); circuit.h(&[0]); - circuit.tracked_operator_labeled("x_check", X(0)); + circuit.tracked_pauli_labeled("x_check", X(0)); let noise = NoiseConfig::new(0.03, 0.0, 0.0, 0.0); let sampler = DemSampler::from_circuit(&circuit, &noise).unwrap(); - assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!(sampler.num_tracked_paulis(), 1); assert_eq!(sampler.num_observables(), 0); assert_eq!( - sampler.labels().tracked_op_labels[0].as_deref(), + sampler.labels().tracked_pauli_labels[0].as_deref(), Some("x_check") ); - let op = sampler.labels().tracked_ops[0].as_ref().unwrap(); + let op = sampler.labels().tracked_paulis[0].as_ref().unwrap(); assert_eq!(op.label.as_deref(), Some("x_check")); assert_eq!( op.kind, - Some(crate::fault_tolerance::DemOutputKind::TrackedOperator) + Some(crate::fault_tolerance::DemOutputKind::TrackedPauli) ); assert_eq!(op.pauli.as_ref().unwrap().to_sparse_str(), "+X0"); } #[test] - fn detector_mode_keeps_observables_unshifted_with_tracked_operators() { + fn detector_mode_keeps_observables_unshifted_with_tracked_paulis() { use pecos_core::pauli::X; let mut circuit = DagCircuit::new(); circuit.pz(&[0]); circuit.h(&[0]); - circuit.tracked_operator_labeled("x_check", X(0)); + circuit.tracked_pauli_labeled("x_check", X(0)); circuit.mz(&[0]); let im = InfluenceBuilder::new(&circuit) @@ -1736,15 +1738,15 @@ mod tests { assert_eq!(sampler.num_dem_outputs(), 1); assert_eq!(sampler.num_observables(), 1); - assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!(sampler.num_tracked_paulis(), 1); assert_eq!(sampler.labels().dem_outputs.len(), 1); assert_eq!( sampler.labels().dem_outputs[0].as_ref().unwrap().kind, Some(crate::fault_tolerance::DemOutputKind::Observable) ); assert_eq!( - sampler.labels().tracked_ops[0].as_ref().unwrap().kind, - Some(crate::fault_tolerance::DemOutputKind::TrackedOperator) + sampler.labels().tracked_paulis[0].as_ref().unwrap().kind, + Some(crate::fault_tolerance::DemOutputKind::TrackedPauli) ); } @@ -1767,7 +1769,7 @@ mod tests { assert_eq!(sampler.num_dem_outputs(), 1); assert_eq!(sampler.num_observables(), 1); - assert_eq!(sampler.num_tracked_ops(), 0); + assert_eq!(sampler.num_tracked_paulis(), 0); assert_eq!( sampler.labels().dem_outputs[0] .as_ref() @@ -1791,7 +1793,7 @@ mod tests { } #[test] - fn from_detector_error_model_preserves_observable_and_tracked_operator_split() { + fn from_detector_error_model_preserves_observable_and_tracked_pauli_split() { use super::super::builder::DemBuilder; use pecos_core::pauli::X; use pecos_quantum::Attribute; @@ -1799,7 +1801,7 @@ mod tests { let mut circuit = DagCircuit::new(); circuit.pz(&[0]); circuit.h(&[0]); - circuit.tracked_operator_labeled("x_check", X(0)); + circuit.tracked_pauli_labeled("x_check", X(0)); circuit.mz(&[0]); circuit.set_attr("num_measurements", Attribute::String("1".to_string())); circuit.set_attr( @@ -1813,14 +1815,14 @@ mod tests { assert_eq!(sampler.num_dem_outputs(), 1); assert_eq!(sampler.num_observables(), 1); - assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!(sampler.num_tracked_paulis(), 1); assert_eq!( sampler.labels().dem_outputs[0].as_ref().unwrap().kind, Some(crate::fault_tolerance::DemOutputKind::Observable) ); assert_eq!( - sampler.labels().tracked_ops[0].as_ref().unwrap().kind, - Some(crate::fault_tolerance::DemOutputKind::TrackedOperator) + sampler.labels().tracked_paulis[0].as_ref().unwrap().kind, + Some(crate::fault_tolerance::DemOutputKind::TrackedPauli) ); } @@ -1835,14 +1837,14 @@ mod tests { assert_eq!(sampler.num_detectors(), 1); assert_eq!(sampler.num_dem_outputs(), 1); assert_eq!(sampler.num_observables(), 1); - assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!(sampler.num_tracked_paulis(), 1); assert_eq!(sampler.observable_ids(), vec![0]); - let err = sampler.tracked_operator_ids().unwrap_err(); + let err = sampler.tracked_pauli_ids().unwrap_err(); assert_eq!(err.backend(), "DemSampler"); - assert_eq!(err.num_tracked_ops(), 1); + assert_eq!(err.num_tracked_paulis(), 1); assert!( err.to_string() - .contains("cannot directly sample tracked operator flips") + .contains("cannot directly sample tracked Pauli flips") ); assert_eq!( sampler.labels().dem_outputs[0] @@ -1853,7 +1855,7 @@ mod tests { Some("obs0") ); assert_eq!( - sampler.labels().tracked_ops[0] + sampler.labels().tracked_paulis[0] .as_ref() .unwrap() .label @@ -1872,7 +1874,7 @@ mod tests { let meas = circuit.mz(&[0]); circuit.detector_labeled("det0", &[meas[0]]); circuit.observable_labeled("obs0", &[meas[0]]); - circuit.tracked_operator_labeled("tracked_x0", X(0)); + circuit.tracked_pauli_labeled("tracked_x0", X(0)); circuit.set_attr("num_measurements", Attribute::String("1".to_string())); circuit.set_attr( "detectors", @@ -1911,14 +1913,14 @@ mod tests { } #[test] - fn sampler_xors_detectors_and_observables_while_tracked_ops_stay_metadata() { + fn sampler_xors_detectors_and_observables_while_tracked_paulis_stay_metadata() { use super::super::types::{DetectorDef, DetectorErrorModel, FaultMechanism}; use pecos_core::pauli::Z; let mut dem = DetectorErrorModel::new(); dem.add_detector(DetectorDef::new(0)); dem.add_observable(DemOutput::new(0).with_records([-1]).with_label("L0")); - dem.add_tracked_operator(DemOutput::new(0).with_pauli(Z(3)).with_label("tracked_z3")); + dem.add_tracked_pauli(DemOutput::new(0).with_pauli(Z(3)).with_label("tracked_z3")); dem.add_direct_contribution(FaultMechanism::from_unsorted([0], [0]), 1.0); dem.add_direct_contribution(FaultMechanism::from_unsorted([0], []), 1.0); @@ -1927,9 +1929,9 @@ mod tests { assert_eq!(sampler.num_detectors(), 1); assert_eq!(sampler.num_observables(), 1); - assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!(sampler.num_tracked_paulis(), 1); assert_eq!( - sampler.labels().tracked_ops[0] + sampler.labels().tracked_paulis[0] .as_ref() .unwrap() .label @@ -1955,11 +1957,11 @@ mod tests { assert_eq!(sampler.num_dem_outputs(), 0); assert_eq!(sampler.num_observables(), 0); - assert_eq!(sampler.num_tracked_ops(), 0); + assert_eq!(sampler.num_tracked_paulis(), 0); } #[test] - fn observable_mask_ignores_tracked_operator_outputs() { + fn observable_mask_ignores_tracked_pauli_outputs() { use super::super::builder::DemBuilder; use pecos_core::pauli::X; use pecos_quantum::Attribute; @@ -1967,7 +1969,7 @@ mod tests { let mut circuit = DagCircuit::new(); circuit.pz(&[0]); circuit.h(&[0]); - circuit.tracked_operator_labeled("x_check", X(0)); + circuit.tracked_pauli_labeled("x_check", X(0)); circuit.mz(&[0]); circuit.set_attr("num_measurements", Attribute::String("1".to_string())); circuit.set_attr( @@ -1981,9 +1983,9 @@ mod tests { assert_eq!(sampler.observable_ids(), vec![0]); assert_eq!( sampler - .tracked_operator_ids() + .tracked_pauli_ids() .unwrap_err() - .num_tracked_ops(), + .num_tracked_paulis(), 1 ); assert_eq!(sampler.observable_dem_output_mask(), 1); @@ -1992,14 +1994,14 @@ mod tests { } #[test] - fn tracked_operator_direct_sampling_fails_explicitly_when_unsupported() { + fn tracked_pauli_direct_sampling_fails_explicitly_when_unsupported() { use super::super::types::{DetectorErrorModel, FaultMechanism}; use pecos_core::pauli::X; let mut dem = DetectorErrorModel::new(); - dem.add_tracked_operator(DemOutput::new(0).with_pauli(X(0)).with_label("tracked_x0")); + dem.add_tracked_pauli(DemOutput::new(0).with_pauli(X(0)).with_label("tracked_x0")); dem.add_direct_contribution( - FaultMechanism::from_unsorted_with_tracked_ops([], [], [0]), + FaultMechanism::from_unsorted_with_tracked_paulis([], [], [0]), 0.25, ); @@ -2007,27 +2009,27 @@ mod tests { let mut rng = PecosRng::seed_from_u64(17); let err = sampler - .sample_tracked_operator_flips(&mut rng) - .expect_err("DemSampler should reject direct tracked-op sampling"); + .sample_tracked_pauli_flips(&mut rng) + .expect_err("DemSampler should reject direct tracked-Pauli sampling"); assert_eq!(err.backend(), "DemSampler"); - assert_eq!(err.num_tracked_ops(), 1); + assert_eq!(err.num_tracked_paulis(), 1); assert!( err.to_string() .contains("samples decoder-facing detectors and observables only") ); let err = sampler - .sample_tracked_operator_batch(4, &mut rng) - .expect_err("DemSampler should reject direct tracked-op batch sampling"); - assert_eq!(err.num_tracked_ops(), 1); + .sample_tracked_pauli_batch(4, &mut rng) + .expect_err("DemSampler should reject direct tracked-Pauli batch sampling"); + assert_eq!(err.num_tracked_paulis(), 1); let empty = DemSampler::from_detector_error_model(&DetectorErrorModel::new()); assert_eq!( - empty.sample_tracked_operator_flips(&mut rng).unwrap(), + empty.sample_tracked_pauli_flips(&mut rng).unwrap(), Vec::::new() ); assert_eq!( - empty.sample_tracked_operator_batch(3, &mut rng).unwrap(), + empty.sample_tracked_pauli_batch(3, &mut rng).unwrap(), vec![Vec::::new(), Vec::new(), Vec::new()] ); } diff --git a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs index 91bb9c2ec..3deda7745 100644 --- a/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/dem_builder/types.rs @@ -13,7 +13,7 @@ //! Types for Detector Error Model (DEM) generation. //! //! This module provides data structures for representing fault mechanisms, -//! detectors, observables, and PECOS tracked operators. +//! detectors, observables, and PECOS tracked Paulis. //! //! # Terminology //! @@ -21,14 +21,14 @@ //! - **Observables** are values observed through measurements. In a DEM they are //! defined by measurement records and rendered as standard `L` observable //! outputs. -//! - **Tracked operators** are not measured values and are not applied to the +//! - **Tracked Paulis** are not measured values and are not applied to the //! simulated computation. They are Pauli operators annotated at a circuit point //! (for example a logical operator, stabilizer, or other Pauli of interest); //! PECOS reports whether each fault event anticommutes with, and therefore //! would flip, that operator under propagation. //! //! PECOS keeps the standard `L` namespace reserved for measurement-record -//! observables only. Tracked Pauli operators are PECOS metadata with their own +//! observables only. Tracked Paulis are PECOS metadata with their own //! ID space, so decoders can ignore them while PECOS tools can still inspect //! them. //! @@ -524,11 +524,11 @@ pub struct FaultMechanism { /// /// New code should treat these as standard observable `L` output channels. pub dem_outputs: SmallVec<[u32; 2]>, - /// PECOS tracked-Pauli operator indices that flip together (sorted). + /// PECOS tracked-Pauli indices that flip together (sorted). /// /// These are rendered as `TP` only in PECOS DEM text. Standard DEM text /// and decoder-facing mechanism tables intentionally ignore them. - pub tracked_ops: SmallVec<[u32; 2]>, + pub tracked_paulis: SmallVec<[u32; 2]>, } impl FaultMechanism { @@ -544,41 +544,41 @@ impl FaultMechanism { detectors: impl IntoIterator, dem_outputs: impl IntoIterator, ) -> Self { - Self::from_unsorted_with_tracked_ops(detectors, dem_outputs, std::iter::empty()) + Self::from_unsorted_with_tracked_paulis(detectors, dem_outputs, std::iter::empty()) } /// Creates a mechanism from unsorted detector, DEM-output, and tracked-Pauli indices. #[must_use] - pub fn from_unsorted_with_tracked_ops( + pub fn from_unsorted_with_tracked_paulis( detectors: impl IntoIterator, dem_outputs: impl IntoIterator, - tracked_ops: impl IntoIterator, + tracked_paulis: impl IntoIterator, ) -> Self { let mut dets: SmallVec<[u32; 4]> = detectors.into_iter().collect(); let mut dem_outputs: SmallVec<[u32; 2]> = dem_outputs.into_iter().collect(); - let mut tracked_ops: SmallVec<[u32; 2]> = tracked_ops.into_iter().collect(); + let mut tracked_paulis: SmallVec<[u32; 2]> = tracked_paulis.into_iter().collect(); dets.sort_unstable(); dem_outputs.sort_unstable(); - tracked_ops.sort_unstable(); + tracked_paulis.sort_unstable(); Self { detectors: dets, dem_outputs, - tracked_ops, + tracked_paulis, } } /// Creates a mechanism from pre-sorted detector and DEM-output indices. #[must_use] pub fn from_sorted(detectors: SmallVec<[u32; 4]>, dem_outputs: SmallVec<[u32; 2]>) -> Self { - Self::from_sorted_with_tracked_ops(detectors, dem_outputs, SmallVec::new()) + Self::from_sorted_with_tracked_paulis(detectors, dem_outputs, SmallVec::new()) } /// Creates a mechanism from pre-sorted detector, DEM-output, and tracked-Pauli indices. #[must_use] - pub fn from_sorted_with_tracked_ops( + pub fn from_sorted_with_tracked_paulis( detectors: SmallVec<[u32; 4]>, dem_outputs: SmallVec<[u32; 2]>, - tracked_ops: SmallVec<[u32; 2]>, + tracked_paulis: SmallVec<[u32; 2]>, ) -> Self { debug_assert!( detectors.windows(2).all(|w| w[0] <= w[1]), @@ -589,13 +589,13 @@ impl FaultMechanism { "dem_outputs must be sorted" ); debug_assert!( - tracked_ops.windows(2).all(|w| w[0] <= w[1]), - "tracked_ops must be sorted" + tracked_paulis.windows(2).all(|w| w[0] <= w[1]), + "tracked_paulis must be sorted" ); Self { detectors, dem_outputs, - tracked_ops, + tracked_paulis, } } @@ -603,7 +603,7 @@ impl FaultMechanism { #[inline] #[must_use] pub fn is_empty(&self) -> bool { - self.detectors.is_empty() && self.dem_outputs.is_empty() && self.tracked_ops.is_empty() + self.detectors.is_empty() && self.dem_outputs.is_empty() && self.tracked_paulis.is_empty() } /// Returns true if this mechanism has no decoder-facing effect. @@ -622,7 +622,7 @@ impl FaultMechanism { Self { detectors: self.detectors.clone(), dem_outputs: self.dem_outputs.clone(), - tracked_ops: SmallVec::new(), + tracked_paulis: SmallVec::new(), } } @@ -640,11 +640,11 @@ impl FaultMechanism { self.dem_outputs.len() } - /// Returns the number of tracked Pauli operator outputs in this mechanism. + /// Returns the number of tracked Pauli outputs in this mechanism. #[inline] #[must_use] - pub fn num_tracked_ops(&self) -> usize { - self.tracked_ops.len() + pub fn num_tracked_paulis(&self) -> usize { + self.tracked_paulis.len() } /// XOR this mechanism with another, returning the combined effect. @@ -655,7 +655,7 @@ impl FaultMechanism { Self { detectors: symmetric_difference_4(&self.detectors, &other.detectors), dem_outputs: symmetric_difference_2(&self.dem_outputs, &other.dem_outputs), - tracked_ops: symmetric_difference_2(&self.tracked_ops, &other.tracked_ops), + tracked_paulis: symmetric_difference_2(&self.tracked_paulis, &other.tracked_paulis), } } @@ -743,7 +743,7 @@ impl PartialEq for FaultMechanism { fn eq(&self, other: &Self) -> bool { self.detectors == other.detectors && self.dem_outputs == other.dem_outputs - && self.tracked_ops == other.tracked_ops + && self.tracked_paulis == other.tracked_paulis } } @@ -753,7 +753,7 @@ impl Hash for FaultMechanism { fn hash(&self, state: &mut H) { self.detectors.hash(state); self.dem_outputs.hash(state); - self.tracked_ops.hash(state); + self.tracked_paulis.hash(state); } } @@ -768,7 +768,7 @@ impl Ord for FaultMechanism { self.detectors .cmp(&other.detectors) .then_with(|| self.dem_outputs.cmp(&other.dem_outputs)) - .then_with(|| self.tracked_ops.cmp(&other.tracked_ops)) + .then_with(|| self.tracked_paulis.cmp(&other.tracked_paulis)) } } @@ -776,10 +776,10 @@ impl fmt::Debug for FaultMechanism { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!( f, - "FaultMechanism(dets={:?}, dem_outputs={:?}, tracked_ops={:?})", + "FaultMechanism(dets={:?}, dem_outputs={:?}, tracked_paulis={:?})", self.detectors.as_slice(), self.dem_outputs.as_slice(), - self.tracked_ops.as_slice() + self.tracked_paulis.as_slice() ) } } @@ -1239,7 +1239,7 @@ impl DetectorDef { /// Metadata for a non-detector output definition. /// -/// Observables are rendered as standard `L` targets. Tracked operators +/// Observables are rendered as standard `L` targets. Tracked Paulis /// use the same metadata shape but live in a separate PECOS-only ID space and /// are never rendered as `L` because they are unmeasured Pauli-operator /// annotations, not measurement-record observables. @@ -1324,16 +1324,16 @@ impl DemOutput { pub fn is_observable(&self) -> bool { match self.kind { Some(DemOutputKind::Observable) => true, - Some(DemOutputKind::TrackedOperator) => false, + Some(DemOutputKind::TrackedPauli) => false, None => !self.records.is_empty(), } } - /// Returns true when this DEM output is a tracked Pauli operator. + /// Returns true when this DEM output is a tracked Pauli. #[must_use] - pub fn is_tracked_operator(&self) -> bool { + pub fn is_tracked_pauli(&self) -> bool { match self.kind { - Some(DemOutputKind::TrackedOperator) => true, + Some(DemOutputKind::TrackedPauli) => true, Some(DemOutputKind::Observable) => false, None => self.pauli.is_some() && self.records.is_empty(), } @@ -1790,7 +1790,7 @@ fn pecos_metadata_dem_output_value(target: &DemOutput) -> serde_json::Value { #[derive(Debug, Clone, Default)] struct ParsedPecosDemMetadata { observables: Vec, - tracked_ops: Vec, + tracked_paulis: Vec, } pub(crate) fn parse_pecos_dem_metadata_line( @@ -1798,11 +1798,11 @@ pub(crate) fn parse_pecos_dem_metadata_line( ) -> Result { let line = line.trim(); let (prefix, payload, forced_kind) = - if let Some(payload) = line.strip_prefix("pecos_tracked_op") { + if let Some(payload) = line.strip_prefix("pecos_tracked_pauli") { ( - "pecos_tracked_op", + "pecos_tracked_pauli", payload.trim(), - Some(DemOutputKind::TrackedOperator), + Some(DemOutputKind::TrackedPauli), ) } else if let Some(payload) = line.strip_prefix("pecos_observable") { ( @@ -1828,9 +1828,9 @@ pub(crate) fn parse_pecos_dem_metadata_line( if let Some(kind) = forced_kind { output.kind = Some(kind); } - if output.is_tracked_operator() && !output.records.is_empty() { + if output.is_tracked_pauli() && !output.records.is_empty() { return Err(PecosDemMetadataError::new( - "tracked operator metadata cannot have measurement records", + "tracked Pauli metadata cannot have measurement records", )); } Ok(output) @@ -1861,6 +1861,14 @@ fn parse_pecos_metadata_json(json: &str) -> Result Result, PecosDemMetadataError> { let Some(values) = root.get(name) else { @@ -1875,9 +1883,9 @@ fn parse_pecos_metadata_json(json: &str) -> Result Result, /// Measurement-record observables rendered as standard `L` outputs. pub observables: Vec, - /// PECOS tracked Pauli operators. + /// PECOS tracked Paulis. /// /// These have their own ID space and are emitted only as PECOS metadata. - pub tracked_ops: Vec, + pub tracked_paulis: Vec, /// Error contributions with source tracking. /// Each contribution tracks whether it came from a direct (X, Z) or decomposable (Y) source. contributions: Vec, @@ -2566,7 +2574,7 @@ impl DetectorErrorModel { Self { detectors: Vec::new(), observables: Vec::new(), - tracked_ops: Vec::new(), + tracked_paulis: Vec::new(), contributions: Vec::new(), graphlike_decomposable_counts: BTreeMap::new(), } @@ -2578,7 +2586,7 @@ impl DetectorErrorModel { Self { detectors: Vec::with_capacity(num_detectors), observables: Vec::with_capacity(num_observables), - tracked_ops: Vec::new(), + tracked_paulis: Vec::new(), contributions: Vec::new(), graphlike_decomposable_counts: BTreeMap::new(), } @@ -2605,18 +2613,18 @@ impl DetectorErrorModel { /// Returns the number of standard DEM `L` observable outputs. /// /// This is a DEM-output alias for [`Self::num_observables`]. It does - /// not include PECOS tracked operators. + /// not include PECOS tracked Paulis. #[inline] #[must_use] pub fn num_dem_outputs(&self) -> usize { self.num_observables() } - /// Returns the number of tracked operators. + /// Returns the number of tracked Paulis. #[inline] #[must_use] - pub fn num_tracked_ops(&self) -> usize { - self.tracked_ops + pub fn num_tracked_paulis(&self) -> usize { + self.tracked_paulis .iter() .map(|op| op.id as usize + 1) .max() @@ -2625,8 +2633,8 @@ impl DetectorErrorModel { /// Returns standard DEM output definitions (`L` observables). /// - /// This DEM-output accessor does not include PECOS tracked operators; - /// use [`Self::tracked_ops`] for those. + /// This DEM-output accessor does not include PECOS tracked Paulis; + /// use [`Self::tracked_paulis`] for those. #[inline] #[must_use] pub fn dem_outputs(&self) -> &[DemOutput] { @@ -2635,7 +2643,7 @@ impl DetectorErrorModel { /// Returns mutable standard DEM output definitions (`L` observables). /// - /// This DEM-output accessor does not include PECOS tracked operators. + /// This DEM-output accessor does not include PECOS tracked Paulis. #[inline] #[must_use] pub fn dem_outputs_mut(&mut self) -> &mut [DemOutput] { @@ -2647,16 +2655,16 @@ impl DetectorErrorModel { self.observables.iter() } - /// Returns all tracked operator definitions. + /// Returns all tracked Pauli definitions. #[inline] #[must_use] - pub fn tracked_ops(&self) -> &[DemOutput] { - &self.tracked_ops + pub fn tracked_paulis(&self) -> &[DemOutput] { + &self.tracked_paulis } - /// Iterates over tracked operators. - pub fn tracked_operators(&self) -> impl Iterator { - self.tracked_ops.iter() + /// Iterates over tracked Paulis. + pub fn iter_tracked_paulis(&self) -> impl Iterator { + self.tracked_paulis.iter() } /// Returns the number of tracked contributions. @@ -2670,7 +2678,7 @@ impl DetectorErrorModel { /// /// The standard DEM string remains decoder-compatible and uses ordinary /// `logical_observable L` declarations. This JSON form preserves the - /// richer PECOS DEM-output information, including tracked Pauli operators. + /// richer PECOS DEM-output information, including tracked Paulis. /// /// # Panics /// @@ -2682,8 +2690,8 @@ impl DetectorErrorModel { .iter() .map(pecos_metadata_dem_output_value) .collect(); - let tracked_ops: Vec = self - .tracked_ops + let tracked_paulis: Vec = self + .tracked_paulis .iter() .map(pecos_metadata_dem_output_value) .collect(); @@ -2692,7 +2700,7 @@ impl DetectorErrorModel { "format": "pecos.dem.metadata", "version": 1, "observables": observables, - "tracked_ops": tracked_ops, + "tracked_paulis": tracked_paulis, })) .expect("serializing PECOS DEM metadata should not fail") } @@ -2713,8 +2721,8 @@ impl DetectorErrorModel { for observable in metadata.observables { self.apply_observable_metadata(observable); } - for tracked_op in metadata.tracked_ops { - self.apply_tracked_op_metadata(tracked_op); + for tracked_pauli in metadata.tracked_paulis { + self.apply_tracked_pauli_metadata(tracked_pauli); } Ok(()) } @@ -2735,7 +2743,7 @@ impl DetectorErrorModel { /// detector targets and `L` measurement-defined observable targets as /// usual, and adds PECOS-only `TP` tracked-Pauli targets for tracked /// operator flips. Metadata follows as `pecos_observable {json}` and - /// `pecos_tracked_op {json}` statements. + /// `pecos_tracked_pauli {json}` statements. /// /// # Panics /// @@ -2795,19 +2803,19 @@ impl DetectorErrorModel { .expect("serializing PECOS observable metadata should not fail"); format!("pecos_observable {payload}") }); - let tracked_op_lines = self.tracked_ops.iter().map(|tracked_op| { - let value = pecos_metadata_dem_output_value(tracked_op); + let tracked_pauli_lines = self.tracked_paulis.iter().map(|tracked_pauli| { + let value = pecos_metadata_dem_output_value(tracked_pauli); let payload = serde_json::to_string(&value) - .expect("serializing PECOS tracked-op metadata should not fail"); - format!("pecos_tracked_op {payload}") + .expect("serializing PECOS tracked-Pauli metadata should not fail"); + format!("pecos_tracked_pauli {payload}") }); - observable_lines.chain(tracked_op_lines).collect() + observable_lines.chain(tracked_pauli_lines).collect() } /// Applies PECOS metadata embedded in extended DEM text. /// /// Standard DEM lines are ignored by this method. PECOS extension lines - /// are parsed and merged into the observable/tracked-op definitions. + /// are parsed and merged into the observable/tracked-Pauli definitions. /// /// # Errors /// @@ -2821,7 +2829,7 @@ impl DetectorErrorModel { if line.is_empty() || line.starts_with('#') { continue; } - if line.starts_with("pecos_observable") || line.starts_with("pecos_tracked_op") { + if line.starts_with("pecos_observable") || line.starts_with("pecos_tracked_pauli") { self.apply_dem_output_metadata(parse_pecos_dem_metadata_line(line)?); } else if line.starts_with("pecos_") { return Err(PecosDemMetadataError::new(format!( @@ -2847,8 +2855,8 @@ impl DetectorErrorModel { } fn apply_dem_output_metadata(&mut self, target: DemOutput) { - if target.is_tracked_operator() { - self.apply_tracked_op_metadata(target); + if target.is_tracked_pauli() { + self.apply_tracked_pauli_metadata(target); } else { self.apply_observable_metadata(target); } @@ -2867,16 +2875,16 @@ impl DetectorErrorModel { } } - fn apply_tracked_op_metadata(&mut self, mut target: DemOutput) { - target.kind = Some(DemOutputKind::TrackedOperator); + fn apply_tracked_pauli_metadata(&mut self, mut target: DemOutput) { + target.kind = Some(DemOutputKind::TrackedPauli); if let Some(existing) = self - .tracked_ops + .tracked_paulis .iter_mut() .find(|existing| existing.id == target.id) { *existing = target; } else { - self.add_tracked_operator(target); + self.add_tracked_pauli(target); } } @@ -3442,10 +3450,10 @@ impl DetectorErrorModel { /// Adds a non-detector DEM output definition. /// /// Observables are stored in the standard `L` namespace. Tracked - /// operators are stored in PECOS metadata with a separate ID space. + /// Paulis are stored in PECOS metadata with a separate ID space. pub fn add_dem_output(&mut self, output: DemOutput) { - if output.is_tracked_operator() { - self.add_tracked_operator(output); + if output.is_tracked_pauli() { + self.add_tracked_pauli(output); } else { self.add_observable(output); } @@ -3494,10 +3502,10 @@ impl DetectorErrorModel { } } - /// Adds a PECOS tracked operator definition. - pub fn add_tracked_operator(&mut self, mut tracked_op: DemOutput) { - tracked_op.kind = Some(DemOutputKind::TrackedOperator); - self.tracked_ops.push(tracked_op); + /// Adds a PECOS tracked Pauli definition. + pub fn add_tracked_pauli(&mut self, mut tracked_pauli: DemOutput) { + tracked_pauli.kind = Some(DemOutputKind::TrackedPauli); + self.tracked_paulis.push(tracked_pauli); } /// Converts the DEM to a string in standard DEM format. @@ -4008,8 +4016,8 @@ fn format_pecos_mechanism_targets(mechanism: &FaultMechanism) -> String { for &dem_output in &mechanism.dem_outputs { targets.push(format!("L{dem_output}")); } - for &tracked_op in &mechanism.tracked_ops { - targets.push(format!("TP{tracked_op}")); + for &tracked_pauli in &mechanism.tracked_paulis { + targets.push(format!("TP{tracked_pauli}")); } targets.join(" ") } @@ -4092,9 +4100,9 @@ mod tests { } #[test] - fn test_error_mechanism_equality_and_hash_include_tracked_ops() { + fn test_error_mechanism_equality_and_hash_include_tracked_paulis() { let standard = FaultMechanism::from_unsorted([0], []); - let with_tracked = FaultMechanism::from_unsorted_with_tracked_ops([0], [], [0]); + let with_tracked = FaultMechanism::from_unsorted_with_tracked_paulis([0], [], [0]); assert_ne!(standard, with_tracked); assert_eq!(standard.standard_effect(), with_tracked.standard_effect()); @@ -4105,13 +4113,13 @@ mod tests { assert_eq!( set.len(), 2, - "internal mechanism identity must keep tracked operators distinct" + "internal mechanism identity must keep tracked Paulis distinct" ); } #[test] - fn test_pecos_target_format_canonicalizes_tracked_ops() { - let mechanism = FaultMechanism::from_unsorted_with_tracked_ops([], [], [2, 0]); + fn test_pecos_target_format_canonicalizes_tracked_paulis() { + let mechanism = FaultMechanism::from_unsorted_with_tracked_paulis([], [], [2, 0]); assert_eq!( DecomposedFault::single(mechanism).to_pecos_targets(), "TP0 TP2" @@ -4134,13 +4142,13 @@ mod tests { } #[test] - fn test_pecos_metadata_json_preserves_tracked_operator_ops() { + fn test_pecos_metadata_json_preserves_tracked_paulis() { use pecos_core::pauli::{X, Z}; let mut dem = DetectorErrorModel::new(); dem.add_dem_output( DemOutput::new(0) - .with_kind(DemOutputKind::TrackedOperator) + .with_kind(DemOutputKind::TrackedPauli) .with_pauli(X(0) & Z(2)) .with_label("track_check"), ); @@ -4149,21 +4157,21 @@ mod tests { let metadata: serde_json::Value = serde_json::from_str(&dem.to_pecos_metadata_json()).unwrap(); let observables = metadata["observables"].as_array().unwrap(); - let tracked_ops = metadata["tracked_ops"].as_array().unwrap(); + let tracked_paulis = metadata["tracked_paulis"].as_array().unwrap(); assert_eq!(metadata["format"], "pecos.dem.metadata"); assert_eq!(metadata["version"], 1); - assert_eq!(tracked_ops[0]["id"], 0); - assert_eq!(tracked_ops[0]["kind"], "tracked_operator"); - assert_eq!(tracked_ops[0]["label"], "track_check"); - assert_eq!(tracked_ops[0]["pauli"], "+X0 Z2"); + assert_eq!(tracked_paulis[0]["id"], 0); + assert_eq!(tracked_paulis[0]["kind"], "tracked_pauli"); + assert_eq!(tracked_paulis[0]["label"], "track_check"); + assert_eq!(tracked_paulis[0]["pauli"], "+X0 Z2"); assert_eq!(observables[0]["id"], 1); assert_eq!(observables[0]["kind"], "observable"); assert_eq!(observables[0]["records"], serde_json::json!([-1, -3])); } #[test] - fn test_dem_counts_keep_detectors_observables_and_tracked_operators_distinct() { + fn test_dem_counts_keep_detectors_observables_and_tracked_paulis_distinct() { use pecos_core::pauli::X; let mut dem = DetectorErrorModel::new(); @@ -4171,17 +4179,20 @@ mod tests { dem.add_dem_output(DemOutput::new(0).with_records([-1, -3])); dem.add_dem_output( DemOutput::new(0) - .with_kind(DemOutputKind::TrackedOperator) + .with_kind(DemOutputKind::TrackedPauli) .with_pauli(X(0)), ); assert_eq!(dem.num_detectors(), 1); assert_eq!(dem.num_dem_outputs(), 1); assert_eq!(dem.num_observables(), 1); - assert_eq!(dem.num_tracked_ops(), 1); + assert_eq!(dem.num_tracked_paulis(), 1); assert_eq!(dem.observables().map(|op| op.id).collect::>(), [0]); assert_eq!( - dem.tracked_operators().map(|op| op.id).collect::>(), + dem.tracked_paulis() + .iter() + .map(|op| op.id) + .collect::>(), [0] ); } @@ -4247,21 +4258,21 @@ mod tests { .with_kind(DemOutputKind::Observable) .with_pauli(X(0)); assert!(observable.is_observable()); - assert!(!observable.is_tracked_operator()); + assert!(!observable.is_tracked_pauli()); let tracked = DemOutput::new(0) - .with_kind(DemOutputKind::TrackedOperator) + .with_kind(DemOutputKind::TrackedPauli) .with_records([-1]); assert!(!tracked.is_observable()); - assert!(tracked.is_tracked_operator()); + assert!(tracked.is_tracked_pauli()); let inferred_observable = DemOutput::new(1).with_records([-1]); assert!(inferred_observable.is_observable()); - assert!(!inferred_observable.is_tracked_operator()); + assert!(!inferred_observable.is_tracked_pauli()); let inferred_tracked = DemOutput::new(1).with_pauli(X(1)); assert!(!inferred_tracked.is_observable()); - assert!(inferred_tracked.is_tracked_operator()); + assert!(inferred_tracked.is_tracked_pauli()); } #[test] @@ -4279,7 +4290,7 @@ mod tests { .with_pecos_metadata_json(&dem.to_pecos_metadata_json()) .unwrap(); assert_eq!(recovered.num_dem_outputs(), 1); - assert_eq!(recovered.num_tracked_ops(), 0); + assert_eq!(recovered.num_tracked_paulis(), 0); assert_eq!(recovered.dem_outputs()[0].id, 0); assert_eq!( recovered.dem_outputs()[0].kind, @@ -4288,7 +4299,7 @@ mod tests { } #[test] - fn test_pecos_metadata_json_round_trips_tracked_operator_metadata() { + fn test_pecos_metadata_json_round_trips_tracked_pauli_metadata() { use pecos_core::pauli::{X, Z}; let mut dem = DetectorErrorModel::new(); @@ -4298,7 +4309,7 @@ mod tests { let mut source = DetectorErrorModel::new(); source.add_dem_output( DemOutput::new(0) - .with_kind(DemOutputKind::TrackedOperator) + .with_kind(DemOutputKind::TrackedPauli) .with_pauli(X(0) & Z(2)) .with_label("track_check"), ); @@ -4308,12 +4319,19 @@ mod tests { .unwrap(); assert_eq!( - dem.tracked_ops()[0].kind, - Some(DemOutputKind::TrackedOperator) + dem.tracked_paulis()[0].kind, + Some(DemOutputKind::TrackedPauli) ); - assert_eq!(dem.tracked_ops()[0].label.as_deref(), Some("track_check")); assert_eq!( - dem.tracked_ops()[0].pauli.as_ref().unwrap().to_sparse_str(), + dem.tracked_paulis()[0].label.as_deref(), + Some("track_check") + ); + assert_eq!( + dem.tracked_paulis()[0] + .pauli + .as_ref() + .unwrap() + .to_sparse_str(), "+X0 Z2" ); assert_eq!(dem.dem_outputs()[1].kind, Some(DemOutputKind::Observable)); @@ -4341,16 +4359,43 @@ mod tests { .unwrap_err(); assert!( err.message() - .contains("missing observables or tracked_ops metadata arrays") + .contains("missing observables or tracked_paulis metadata arrays") ); } #[test] - fn test_pecos_metadata_json_parser_rejects_old_generic_kind_names() { + fn test_pecos_metadata_json_parser_rejects_legacy_tracked_fields() { let json = r#"{ "format": "pecos.dem.metadata", "version": 1, + "observables": [], + "tracked_paulis": [], "tracked_ops": [ + { + "id": 0, + "kind": "tracked_op", + "label": "old_name", + "pauli": "+X0", + "records": [] + } + ] + }"#; + + let err = DetectorErrorModel::new() + .with_pecos_metadata_json(json) + .unwrap_err(); + assert!( + err.message() + .contains("unsupported legacy metadata field: tracked_ops; use tracked_paulis") + ); + } + + #[test] + fn test_pecos_metadata_json_parser_rejects_old_generic_kind_names() { + let json = r#"{ + "format": "pecos.dem.metadata", + "version": 1, + "tracked_paulis": [ { "id": 4, "kind": "old_kind", @@ -4372,7 +4417,7 @@ mod tests { let alias_json = r#"{ "format": "pecos.dem.metadata", "version": 1, - "tracked_ops": [ + "tracked_paulis": [ { "id": 4, "kind": "pauli_operator", @@ -4392,14 +4437,14 @@ mod tests { } #[test] - fn test_pecos_metadata_json_rejects_records_on_tracked_operator() { + fn test_pecos_metadata_json_rejects_records_on_tracked_pauli() { let json = r#"{ "format": "pecos.dem.metadata", "version": 1, - "tracked_ops": [ + "tracked_paulis": [ { "id": 0, - "kind": "tracked_operator", + "kind": "tracked_pauli", "pauli": "X0", "records": [-1] } @@ -4411,7 +4456,7 @@ mod tests { .unwrap_err(); assert!( err.message() - .contains("tracked operator DEM output 0 cannot have measurement records") + .contains("tracked Pauli DEM output 0 cannot have measurement records") ); } @@ -4423,12 +4468,12 @@ mod tests { dem.add_detector(DetectorDef::new(0)); dem.add_dem_output( DemOutput::new(0) - .with_kind(DemOutputKind::TrackedOperator) + .with_kind(DemOutputKind::TrackedPauli) .with_pauli(X(0) & Z(2)) .with_label("track_check"), ); dem.add_direct_contribution( - FaultMechanism::from_unsorted_with_tracked_ops([0], [], [0]), + FaultMechanism::from_unsorted_with_tracked_paulis([0], [], [0]), 0.01, ); @@ -4440,21 +4485,21 @@ mod tests { let pecos_text = dem.to_pecos_string(); assert!(pecos_text.contains("error(0.01) D0 TP0")); - assert!(pecos_text.contains("pecos_tracked_op")); - assert!(pecos_text.contains(r#""kind":"tracked_operator""#)); + assert!(pecos_text.contains("pecos_tracked_pauli")); + assert!(pecos_text.contains(r#""kind":"tracked_pauli""#)); assert!(pecos_text.contains(r#""pauli":"+X0 Z2""#)); let recovered = DetectorErrorModel::new() .with_pecos_dem_metadata(&pecos_text) .unwrap(); assert_eq!(recovered.num_dem_outputs(), 0); - assert_eq!(recovered.num_tracked_ops(), 1); + assert_eq!(recovered.num_tracked_paulis(), 1); assert_eq!( - recovered.tracked_ops()[0].kind, - Some(DemOutputKind::TrackedOperator) + recovered.tracked_paulis()[0].kind, + Some(DemOutputKind::TrackedPauli) ); assert_eq!( - recovered.tracked_ops()[0] + recovered.tracked_paulis()[0] .pauli .as_ref() .unwrap() @@ -4462,13 +4507,13 @@ mod tests { "+X0 Z2" ); assert_eq!( - recovered.tracked_ops()[0].label.as_deref(), + recovered.tracked_paulis()[0].label.as_deref(), Some("track_check") ); } #[test] - fn test_pecos_dem_text_round_trips_observables_and_tracked_ops() { + fn test_pecos_dem_text_round_trips_observables_and_tracked_paulis() { use pecos_core::pauli::Z; let mut dem = DetectorErrorModel::new(); @@ -4477,12 +4522,12 @@ mod tests { dem.add_dem_output(DemOutput::new(1).with_records([-2])); dem.add_dem_output( DemOutput::new(0) - .with_kind(DemOutputKind::TrackedOperator) + .with_kind(DemOutputKind::TrackedPauli) .with_pauli(Z(3)) .with_label("tracked_z3"), ); dem.add_direct_contribution( - FaultMechanism::from_unsorted_with_tracked_ops([0], [0], [0]), + FaultMechanism::from_unsorted_with_tracked_paulis([0], [0], [0]), 0.01, ); dem.add_direct_contribution(FaultMechanism::from_unsorted([], [1]), 0.02); @@ -4492,19 +4537,19 @@ mod tests { assert!(stim_text.contains("logical_observable L1")); assert!(!stim_text.contains("logical_observable L2")); assert!(!stim_text.contains("TP0")); - assert!(!stim_text.contains("pecos_tracked_op")); + assert!(!stim_text.contains("pecos_tracked_pauli")); let pecos_text = dem.to_pecos_string(); assert!(pecos_text.contains("error(0.01) D0 L0 TP0")); assert!(pecos_text.contains("pecos_observable")); - assert!(pecos_text.contains("pecos_tracked_op")); + assert!(pecos_text.contains("pecos_tracked_pauli")); let recovered = DetectorErrorModel::new() .with_pecos_dem_metadata(&pecos_text) .unwrap(); assert_eq!(recovered.num_observables(), 2); assert_eq!(recovered.num_dem_outputs(), 2); - assert_eq!(recovered.num_tracked_ops(), 1); + assert_eq!(recovered.num_tracked_paulis(), 1); assert_eq!( recovered .dem_outputs() @@ -4515,14 +4560,14 @@ mod tests { ); assert_eq!( recovered - .tracked_ops() + .tracked_paulis() .iter() .map(|op| op.id) .collect::>(), [0] ); assert_eq!( - recovered.tracked_ops()[0] + recovered.tracked_paulis()[0] .pauli .as_ref() .unwrap() @@ -4530,7 +4575,7 @@ mod tests { "+Z3" ); assert_eq!( - recovered.tracked_ops()[0].label.as_deref(), + recovered.tracked_paulis()[0].label.as_deref(), Some("tracked_z3") ); } @@ -4543,13 +4588,13 @@ mod tests { let mut dem = DetectorErrorModel::new(); dem.add_detector(DetectorDef::new(0).with_coords([1.0, 2.0, 3.0])); dem.add_observable(DemOutput::new(0).with_records([-1]).with_label("L0")); - dem.add_tracked_operator( + dem.add_tracked_pauli( DemOutput::new(0) .with_pauli(X(0) & Z(2)) .with_label("tracked_x0_z2"), ); dem.add_direct_contribution( - FaultMechanism::from_unsorted_with_tracked_ops([0], [0], [0]), + FaultMechanism::from_unsorted_with_tracked_paulis([0], [0], [0]), 0.25, ); @@ -4558,18 +4603,18 @@ mod tests { assert_eq!(parsed.num_detectors, 1); assert_eq!(parsed.num_dem_outputs(), 1); - assert_eq!(parsed.num_tracked_ops(), 1); + assert_eq!(parsed.num_tracked_paulis(), 1); assert_eq!(parsed.mechanisms.len(), 1); assert_eq!(parsed.mechanisms[0].format_targets(), "D0 L0 TP0"); assert_eq!(parsed.mechanisms[0].components[0].detectors, vec![0]); assert_eq!(parsed.mechanisms[0].components[0].observables, vec![0]); - assert_eq!(parsed.mechanisms[0].components[0].tracked_ops, vec![0]); + assert_eq!(parsed.mechanisms[0].components[0].tracked_paulis, vec![0]); assert_eq!( parsed.dem_outputs[0].as_ref().unwrap().label.as_deref(), Some("L0") ); assert_eq!( - parsed.tracked_ops[0] + parsed.tracked_paulis[0] .as_ref() .unwrap() .pauli @@ -4585,20 +4630,20 @@ mod tests { use pecos_core::pauli::X; let mut dem = DetectorErrorModel::new(); - dem.add_tracked_operator(DemOutput::new(0).with_pauli(X(0)).with_label("tracked_x0")); + dem.add_tracked_pauli(DemOutput::new(0).with_pauli(X(0)).with_label("tracked_x0")); dem.add_direct_contribution( - FaultMechanism::from_unsorted_with_tracked_ops([], [], [0]), + FaultMechanism::from_unsorted_with_tracked_paulis([], [], [0]), 0.25, ); let standard_text = dem.to_string(); assert!(!standard_text.contains("error(")); assert!(!standard_text.contains("TP0")); - assert!(!standard_text.contains("pecos_tracked_op")); + assert!(!standard_text.contains("pecos_tracked_pauli")); let pecos_text = dem.to_pecos_string(); assert!(pecos_text.contains("error(0.25) TP0")); - assert!(pecos_text.contains("pecos_tracked_op")); + assert!(pecos_text.contains("pecos_tracked_pauli")); let (mechanisms, coords) = dem.to_mechanisms(); assert!(mechanisms.is_empty()); @@ -4606,19 +4651,19 @@ mod tests { } #[test] - fn test_standard_projection_merges_effects_that_differ_only_by_tracked_ops() { + fn test_standard_projection_merges_effects_that_differ_only_by_tracked_paulis() { use pecos_core::pauli::{X, Z}; let mut dem = DetectorErrorModel::new(); dem.add_detector(DetectorDef::new(0)); - dem.add_tracked_operator(DemOutput::new(0).with_pauli(X(0)).with_label("tracked_x0")); - dem.add_tracked_operator(DemOutput::new(1).with_pauli(Z(0)).with_label("tracked_z0")); + dem.add_tracked_pauli(DemOutput::new(0).with_pauli(X(0)).with_label("tracked_x0")); + dem.add_tracked_pauli(DemOutput::new(1).with_pauli(Z(0)).with_label("tracked_z0")); dem.add_direct_contribution( - FaultMechanism::from_unsorted_with_tracked_ops([0], [], [0]), + FaultMechanism::from_unsorted_with_tracked_paulis([0], [], [0]), 0.1, ); dem.add_direct_contribution( - FaultMechanism::from_unsorted_with_tracked_ops([0], [], [1]), + FaultMechanism::from_unsorted_with_tracked_paulis([0], [], [1]), 0.2, ); @@ -4639,19 +4684,19 @@ mod tests { } #[test] - fn test_pecos_dem_preserves_effects_that_differ_by_tracked_ops() { + fn test_pecos_dem_preserves_effects_that_differ_by_tracked_paulis() { use pecos_core::pauli::{X, Z}; let mut dem = DetectorErrorModel::new(); dem.add_detector(DetectorDef::new(0)); - dem.add_tracked_operator(DemOutput::new(0).with_pauli(X(0)).with_label("tracked_x0")); - dem.add_tracked_operator(DemOutput::new(1).with_pauli(Z(0)).with_label("tracked_z0")); + dem.add_tracked_pauli(DemOutput::new(0).with_pauli(X(0)).with_label("tracked_x0")); + dem.add_tracked_pauli(DemOutput::new(1).with_pauli(Z(0)).with_label("tracked_z0")); dem.add_direct_contribution( - FaultMechanism::from_unsorted_with_tracked_ops([0], [], [0]), + FaultMechanism::from_unsorted_with_tracked_paulis([0], [], [0]), 0.1, ); dem.add_direct_contribution( - FaultMechanism::from_unsorted_with_tracked_ops([0], [], [1]), + FaultMechanism::from_unsorted_with_tracked_paulis([0], [], [1]), 0.2, ); @@ -4666,33 +4711,33 @@ mod tests { } #[test] - fn test_standard_dem_serialization_never_shifts_observable_ids_for_tracked_ops() { + fn test_standard_dem_serialization_never_shifts_observable_ids_for_tracked_paulis() { use pecos_core::pauli::{X, Z}; let mut dem = DetectorErrorModel::new(); dem.add_detector(DetectorDef::new(0)); dem.add_observable(DemOutput::new(0).with_records([-1]).with_label("L0")); dem.add_observable(DemOutput::new(2).with_records([-2]).with_label("L2")); - dem.add_tracked_operator( + dem.add_tracked_pauli( DemOutput::new(0) - .with_kind(DemOutputKind::TrackedOperator) + .with_kind(DemOutputKind::TrackedPauli) .with_pauli(X(0)) .with_label("tracked_x0"), ); - dem.add_tracked_operator( + dem.add_tracked_pauli( DemOutput::new(1) - .with_kind(DemOutputKind::TrackedOperator) + .with_kind(DemOutputKind::TrackedPauli) .with_pauli(Z(3)) .with_label("tracked_z3"), ); dem.add_direct_contribution( - FaultMechanism::from_unsorted_with_tracked_ops([0], [0, 2], [1]), + FaultMechanism::from_unsorted_with_tracked_paulis([0], [0, 2], [1]), 0.01, ); assert_eq!(dem.num_observables(), 3); assert_eq!(dem.num_dem_outputs(), 3); - assert_eq!(dem.num_tracked_ops(), 2); + assert_eq!(dem.num_tracked_paulis(), 2); let standard_text = dem.to_string(); assert!(standard_text.contains("logical_observable L0")); @@ -4702,12 +4747,12 @@ mod tests { assert!(standard_text.contains("error(0.01) D0 L0 L2")); assert!(!standard_text.contains("TP1")); assert!(!standard_text.contains("pecos_observable")); - assert!(!standard_text.contains("pecos_tracked_op")); + assert!(!standard_text.contains("pecos_tracked_pauli")); let pecos_text = dem.to_pecos_string(); assert!(pecos_text.contains("error(0.01) D0 L0 L2 TP1")); assert!(pecos_text.contains(r#""kind":"observable""#)); - assert!(pecos_text.contains(r#""kind":"tracked_operator""#)); + assert!(pecos_text.contains(r#""kind":"tracked_pauli""#)); assert!(pecos_text.contains(r#""id":0"#)); assert!(pecos_text.contains(r#""id":2"#)); assert!(pecos_text.contains(r#""pauli":"+X0""#)); @@ -4717,7 +4762,7 @@ mod tests { .with_pecos_dem_metadata(&pecos_text) .unwrap(); assert_eq!(recovered.num_dem_outputs(), 3); - assert_eq!(recovered.num_tracked_ops(), 2); + assert_eq!(recovered.num_tracked_paulis(), 2); assert_eq!( recovered .dem_outputs() @@ -4728,7 +4773,7 @@ mod tests { ); assert_eq!( recovered - .tracked_ops() + .tracked_paulis() .iter() .map(|op| op.id) .collect::>(), @@ -4749,14 +4794,14 @@ mod tests { .with_records([-2, -1]) .with_label("logical_aux"), ); - dem.add_tracked_operator( + dem.add_tracked_pauli( DemOutput::new(0) .with_pauli(X(0) & Z(2)) .with_label("tracked_x0_z2"), ); - dem.add_tracked_operator(DemOutput::new(2).with_pauli(Y(5)).with_label("tracked_y5")); + dem.add_tracked_pauli(DemOutput::new(2).with_pauli(Y(5)).with_label("tracked_y5")); dem.add_direct_contribution( - FaultMechanism::from_unsorted_with_tracked_ops([0, 1], [3], [2]), + FaultMechanism::from_unsorted_with_tracked_paulis([0, 1], [3], [2]), 0.125, ); @@ -4767,7 +4812,7 @@ mod tests { assert!(standard_text.contains("logical_observable L3")); assert!(standard_text.contains("error(0.125) D0 D1 L3")); assert!(!standard_text.contains("TP2")); - assert!(!standard_text.contains("pecos_tracked_op")); + assert!(!standard_text.contains("pecos_tracked_pauli")); let pecos_text = format!( "# ordinary comments and standard DEM lines are allowed\n{}\n", @@ -4778,7 +4823,7 @@ mod tests { .unwrap(); assert_eq!(recovered.num_observables(), 4); assert_eq!(recovered.num_dem_outputs(), 4); - assert_eq!(recovered.num_tracked_ops(), 3); + assert_eq!(recovered.num_tracked_paulis(), 3); assert_eq!( recovered .dem_outputs() @@ -4789,14 +4834,14 @@ mod tests { ); assert_eq!( recovered - .tracked_ops() + .tracked_paulis() .iter() .map(|op| (op.id, op.label.as_deref())) .collect::>(), [(0, Some("tracked_x0_z2")), (2, Some("tracked_y5"))] ); assert_eq!( - recovered.tracked_ops()[0] + recovered.tracked_paulis()[0] .pauli .as_ref() .unwrap() @@ -4804,7 +4849,7 @@ mod tests { "+X0 Z2" ); assert_eq!( - recovered.tracked_ops()[1] + recovered.tracked_paulis()[1] .pauli .as_ref() .unwrap() @@ -4818,7 +4863,7 @@ mod tests { assert!(!reserialized.contains("logical_observable L2")); assert!(reserialized.contains("logical_observable L3")); assert!(reserialized.contains(r#""kind":"observable""#)); - assert!(reserialized.contains(r#""kind":"tracked_operator""#)); + assert!(reserialized.contains(r#""kind":"tracked_pauli""#)); assert!(reserialized.contains(r#""pauli":"+X0 Z2""#)); assert!(reserialized.contains(r#""pauli":"+Y5""#)); assert!( @@ -4836,14 +4881,14 @@ mod tests { dem.add_detector(DetectorDef::new(0).with_records([-1])); dem.add_observable(DemOutput::new(0).with_records([-1]).with_label("L0")); dem.add_observable(DemOutput::new(3).with_records([-2]).with_label("L3")); - dem.add_tracked_operator( + dem.add_tracked_pauli( DemOutput::new(0) .with_pauli(X(0) & Z(2)) .with_label("tracked_x0_z2"), ); - dem.add_tracked_operator(DemOutput::new(3).with_pauli(Y(5)).with_label("tracked_y5")); + dem.add_tracked_pauli(DemOutput::new(3).with_pauli(Y(5)).with_label("tracked_y5")); dem.add_direct_contribution( - FaultMechanism::from_unsorted_with_tracked_ops([0], [3], [3]), + FaultMechanism::from_unsorted_with_tracked_paulis([0], [3], [3]), 0.125, ); @@ -4866,10 +4911,10 @@ mod tests { let parsed: ParsedDem = dem.to_pecos_string().parse().unwrap(); assert_eq!(parsed.num_dem_outputs(), 4); - assert_eq!(parsed.num_tracked_ops(), 4); + assert_eq!(parsed.num_tracked_paulis(), 4); assert_eq!(parsed.mechanisms[0].format_targets(), "D0 L3 TP3"); assert_eq!(parsed.mechanisms[0].components[0].observables, vec![3]); - assert_eq!(parsed.mechanisms[0].components[0].tracked_ops, vec![3]); + assert_eq!(parsed.mechanisms[0].components[0].tracked_paulis, vec![3]); assert_eq!( parsed.dem_outputs[0].as_ref().unwrap().label.as_deref(), Some("L0") @@ -4879,7 +4924,7 @@ mod tests { Some("L3") ); assert_eq!( - parsed.tracked_ops[0] + parsed.tracked_paulis[0] .as_ref() .unwrap() .pauli @@ -4889,7 +4934,7 @@ mod tests { "+X0 Z2" ); assert_eq!( - parsed.tracked_ops[3].as_ref().unwrap().label.as_deref(), + parsed.tracked_paulis[3].as_ref().unwrap().label.as_deref(), Some("tracked_y5") ); } @@ -4897,11 +4942,11 @@ mod tests { #[test] fn test_pecos_dem_metadata_parser_rejects_malformed_extension_line() { let err = DetectorErrorModel::new() - .with_pecos_dem_metadata("error(0.01) D0\npecos_tracked_op not-json") + .with_pecos_dem_metadata("error(0.01) D0\npecos_tracked_pauli not-json") .unwrap_err(); assert!( err.message() - .contains("invalid pecos_tracked_op JSON payload") + .contains("invalid pecos_tracked_pauli JSON payload") ); } @@ -4917,9 +4962,21 @@ mod tests { ); } + #[test] + fn test_pecos_dem_metadata_parser_rejects_legacy_tracked_extension_line() { + let err = DetectorErrorModel::new() + .with_pecos_dem_metadata(r#"pecos_tracked_op {"id":0,"pauli":"+X0"}"#) + .unwrap_err(); + + assert!( + err.message() + .contains("unsupported PECOS DEM extension line: pecos_tracked_op") + ); + } + #[test] fn test_decomposed_error_single() { - let mechanism = FaultMechanism::from_unsorted_with_tracked_ops([0, 1], [0], [2]); + let mechanism = FaultMechanism::from_unsorted_with_tracked_paulis([0, 1], [0], [2]); let decomposed = DecomposedFault::single(mechanism.clone()); assert_eq!(decomposed.components.len(), 1); diff --git a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs index db1ffee17..a369a1683 100644 --- a/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs +++ b/crates/pecos-qec/src/fault_tolerance/fault_sampler.rs @@ -59,7 +59,7 @@ impl fmt::Display for UnsupportedGateError { Supported: H, X, Y, Z, SZ, SZdg, SX, SXdg, SY, SYdg, F, Fdg, \ CX, CY, CZ, SXX, SXXdg, SYY, SYYdg, SZZ, SZZdg, SWAP, \ MZ/MeasureFree/MeasureLeaked, PZ, QAlloc, QFree, I, Idle, \ - plus metadata (MeasCrosstalk*, PauliOperatorMeta).", + plus metadata (MeasCrosstalk*, TrackedPauliMeta).", self.gate_type, self.tick, self.gate_in_tick, self.qubits ) } @@ -129,7 +129,7 @@ fn is_supported_noop_or_metadata_gate(gate_type: GateType) -> bool { | GateType::Idle | GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload - | GateType::PauliOperatorMeta + | GateType::TrackedPauliMeta ) } @@ -211,7 +211,7 @@ pub(crate) enum PauliType { /// /// **No-op** (pass through without noise or transformation): /// - `I`, `Idle`, `QFree`, `MeasCrosstalkGlobalPayload`, -/// `MeasCrosstalkLocalPayload`, `PauliOperatorMeta` +/// `MeasCrosstalkLocalPayload`, `TrackedPauliMeta` /// /// Any gate not in the above lists returns [`UnsupportedGateError`]. /// @@ -315,7 +315,7 @@ fn propagate_single_effect( start: usize, gates: &[GateLoc], meas_positions: &HashMap, - tracked_ops: &[PauliString], + tracked_paulis: &[PauliString], ) -> PropagatedFaultEffect { let mut prop = BitmaskPauliProp::new(); match pauli { @@ -325,10 +325,10 @@ fn propagate_single_effect( } let affected_measurements = propagate_forward(&mut prop, start, gates, meas_positions); - let affected_tracked_ops = tracked_ops_flipped_by(&prop, tracked_ops); + let affected_tracked_paulis = tracked_paulis_flipped_by(&prop, tracked_paulis); PropagatedFaultEffect { affected_measurements, - affected_tracked_ops, + affected_tracked_paulis, } } @@ -338,7 +338,7 @@ fn propagate_pair_effect( start: usize, gates: &[GateLoc], meas_positions: &HashMap, - tracked_ops: &[PauliString], + tracked_paulis: &[PauliString], ) -> PropagatedFaultEffect { let mut prop = BitmaskPauliProp::new(); for (pauli, qubit) in faults { @@ -350,17 +350,17 @@ fn propagate_pair_effect( } let affected_measurements = propagate_forward(&mut prop, start, gates, meas_positions); - let affected_tracked_ops = tracked_ops_flipped_by(&prop, tracked_ops); + let affected_tracked_paulis = tracked_paulis_flipped_by(&prop, tracked_paulis); PropagatedFaultEffect { affected_measurements, - affected_tracked_ops, + affected_tracked_paulis, } } #[derive(Clone, Debug, PartialEq, Eq)] struct PropagatedFaultEffect { affected_measurements: BTreeSet, - affected_tracked_ops: Vec, + affected_tracked_paulis: Vec, } #[derive(Default)] @@ -381,12 +381,12 @@ impl PropagatedEffectCache { start: usize, gates: &[GateLoc], meas_positions: &HashMap, - tracked_ops: &[PauliString], + tracked_paulis: &[PauliString], ) -> PropagatedFaultEffect { self.singles .entry((start, pauli, qubit)) .or_insert_with(|| { - propagate_single_effect(pauli, qubit, start, gates, meas_positions, tracked_ops) + propagate_single_effect(pauli, qubit, start, gates, meas_positions, tracked_paulis) }) .clone() } @@ -405,9 +405,9 @@ fn xor_fault_effects( PropagatedFaultEffect { affected_measurements, - affected_tracked_ops: xor_sorted_unique_indices( - &left.affected_tracked_ops, - &right.affected_tracked_ops, + affected_tracked_paulis: xor_sorted_unique_indices( + &left.affected_tracked_paulis, + &right.affected_tracked_paulis, ), } } @@ -583,8 +583,8 @@ pub struct FaultAlternative { pub affected_detectors: Vec, /// Observable indices flipped. pub affected_observables: Vec, - /// Tracked-operator indices flipped. - pub affected_tracked_ops: Vec, + /// Tracked-Pauli indices flipped. + pub affected_tracked_paulis: Vec, /// Probability of this alternative conditioned on the mechanism firing (`1/k`). pub conditional_probability: f64, /// Marginal probability of this specific alternative at this location: `p_i / k_i`. @@ -655,8 +655,8 @@ pub struct FaultConfiguration { pub affected_detectors: Vec, /// Combined observable indices (XOR parity). pub affected_observables: Vec, - /// Combined tracked-operator indices (XOR parity). - pub affected_tracked_ops: Vec, + /// Combined tracked-Pauli indices (XOR parity). + pub affected_tracked_paulis: Vec, /// Product of selected alternatives' `absolute_probability`. pub selected_probability: f64, /// `selected_probability * product(unselected no_fault_probability)`. @@ -872,7 +872,7 @@ impl FaultConfigCursor { affected_measurements: Vec::new(), affected_detectors: Vec::new(), affected_observables: Vec::new(), - affected_tracked_ops: Vec::new(), + affected_tracked_paulis: Vec::new(), selected_probability: 1.0, configuration_probability: no_fault_prob, }; @@ -881,7 +881,7 @@ impl FaultConfigCursor { let mut meas_set = std::collections::BTreeSet::new(); let mut det_set = std::collections::BTreeSet::new(); let mut obs_set = std::collections::BTreeSet::new(); - let mut tracked_op_set = std::collections::BTreeSet::new(); + let mut tracked_pauli_set = std::collections::BTreeSet::new(); let mut selected_prob = 1.0; for i in 0..self.k { @@ -905,9 +905,9 @@ impl FaultConfigCursor { obs_set.insert(o); } } - for &op in &alt.affected_tracked_ops { - if !tracked_op_set.remove(&op) { - tracked_op_set.insert(op); + for &op in &alt.affected_tracked_paulis { + if !tracked_pauli_set.remove(&op) { + tracked_pauli_set.insert(op); } } } @@ -940,7 +940,7 @@ impl FaultConfigCursor { affected_measurements: meas_set.into_iter().collect(), affected_detectors: det_set.into_iter().collect(), affected_observables: obs_set.into_iter().collect(), - affected_tracked_ops: tracked_op_set.into_iter().collect(), + affected_tracked_paulis: tracked_pauli_set.into_iter().collect(), selected_probability: selected_prob, configuration_probability: selected_prob * unselected_no_fault, } @@ -1014,9 +1014,9 @@ impl Iterator for OwnedFaultConfigIter { /// Build a fault catalog from a `TickCircuit` and noise parameters. /// /// Returns per-location, per-alternative fault data including Pauli labels, -/// affected detectors, observables, tracked operators, and probability fields. +/// affected detectors, observables, tracked Paulis, and probability fields. /// -/// Reads detector/observable metadata and tracked-operator annotations +/// Reads detector/observable metadata and tracked-Pauli annotations /// from the circuit when present. /// /// # Errors @@ -1039,7 +1039,7 @@ fn build_structural_fault_catalog(tc: &TickCircuit) -> Result Result Result Result Result Result Result Result Result Result Result Result Result Vec> { parse_records_from_meta(tc, "observables") } -fn parse_tracked_operator_annotations(tc: &TickCircuit) -> Vec { +fn parse_tracked_pauli_annotations(tc: &TickCircuit) -> Vec { tc.annotations() .iter() - .filter(|ann| matches!(ann.kind, AnnotationKind::TrackedOperator)) + .filter(|ann| matches!(ann.kind, AnnotationKind::TrackedPauli)) .map(|ann| { let mut pauli = ann.pauli.clone(); pauli.set_phase(pecos_core::QuarterPhase::PlusOne); @@ -1330,13 +1330,16 @@ fn parse_tracked_operator_annotations(tc: &TickCircuit) -> Vec { .collect() } -fn tracked_ops_flipped_by(prop: &BitmaskPauliProp, tracked_ops: &[PauliString]) -> Vec { - tracked_ops +fn tracked_paulis_flipped_by( + prop: &BitmaskPauliProp, + tracked_paulis: &[PauliString], +) -> Vec { + tracked_paulis .iter() .enumerate() - .filter_map(|(idx, tracked_op)| { + .filter_map(|(idx, tracked_pauli)| { let mut parity = false; - for &(pauli, qubit) in tracked_op.paulis() { + for &(pauli, qubit) in tracked_pauli.paulis() { let q = qubit.index(); match pauli { Pauli::X => parity ^= prop.contains_z(q), @@ -1418,7 +1421,7 @@ fn catalog_effect_parts( let affected: Vec = effect.affected_measurements.into_iter().collect(); let dets = record_effect_index.detectors_for_measurements(&affected); let obs = record_effect_index.observables_for_measurements(&affected); - (affected, dets, obs, effect.affected_tracked_ops) + (affected, dets, obs, effect.affected_tracked_paulis) } fn records_by_measurement(records_by_output: &[Vec], num_meas: usize) -> Vec> { @@ -1581,7 +1584,7 @@ pub fn symbolic_measurement_history( | GateType::QFree | GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload - | GateType::PauliOperatorMeta => {} + | GateType::TrackedPauliMeta => {} other => { return Err(UnsupportedGateError { gate_type: other, @@ -2052,7 +2055,7 @@ mod tests { tc.get_tick_mut(1) .unwrap() .add_gate(pecos_core::Gate::simple( - GateType::PauliOperatorMeta, + GateType::TrackedPauliMeta, vec![QubitId(1), QubitId(2)], )); tc.tick().mz(&[QubitId(0)]); @@ -2235,22 +2238,23 @@ mod tests { tc.tick().cx(&[(QubitId(0), QubitId(1))]); tc.tick().h(&[QubitId(1)]); tc.tick().mz(&[QubitId(0), QubitId(1)]); - tc.tracked_operator_labeled("tracked_z0", PauliString::z(0)); - tc.tracked_operator_labeled("tracked_z1", PauliString::z(1)); + tc.tracked_pauli_labeled("tracked_z0", PauliString::z(0)); + tc.tracked_pauli_labeled("tracked_z1", PauliString::z(1)); let (gates, meas_pos) = flatten_tick_circuit(&tc); - let tracked_ops = parse_tracked_operator_annotations(&tc); + let tracked_paulis = parse_tracked_pauli_annotations(&tc); let start = 1; - let left = propagate_single_effect(PauliType::X, 0, start, &gates, &meas_pos, &tracked_ops); + let left = + propagate_single_effect(PauliType::X, 0, start, &gates, &meas_pos, &tracked_paulis); let right = - propagate_single_effect(PauliType::Z, 1, start, &gates, &meas_pos, &tracked_ops); + propagate_single_effect(PauliType::Z, 1, start, &gates, &meas_pos, &tracked_paulis); let combined = xor_fault_effects(&left, &right); let direct = propagate_pair_effect( [(PauliType::X, 0), (PauliType::Z, 1)], start, &gates, &meas_pos, - &tracked_ops, + &tracked_paulis, ); assert_eq!(combined, direct); @@ -2261,22 +2265,22 @@ mod tests { let mut tc = TickCircuit::new(); tc.tick().h(&[QubitId(0)]); tc.tick().mz(&[QubitId(0)]); - tc.tracked_operator_labeled("tracked_x0", PauliString::x(0)); + tc.tracked_pauli_labeled("tracked_x0", PauliString::x(0)); let (gates, meas_pos) = flatten_tick_circuit(&tc); - let tracked_ops = parse_tracked_operator_annotations(&tc); - let fresh = propagate_single_effect(PauliType::Z, 0, 0, &gates, &meas_pos, &tracked_ops); + let tracked_paulis = parse_tracked_pauli_annotations(&tc); + let fresh = propagate_single_effect(PauliType::Z, 0, 0, &gates, &meas_pos, &tracked_paulis); let mut cache = PropagatedEffectCache::default(); - let first = cache.single(PauliType::Z, 0, 0, &gates, &meas_pos, &tracked_ops); + let first = cache.single(PauliType::Z, 0, 0, &gates, &meas_pos, &tracked_paulis); assert_eq!(first, fresh); assert_eq!(cache.len(), 1); let mut mutated_clone = first.clone(); mutated_clone.affected_measurements.clear(); - mutated_clone.affected_tracked_ops.clear(); + mutated_clone.affected_tracked_paulis.clear(); - let second = cache.single(PauliType::Z, 0, 0, &gates, &meas_pos, &tracked_ops); + let second = cache.single(PauliType::Z, 0, 0, &gates, &meas_pos, &tracked_paulis); assert_eq!(second, fresh); assert_ne!(second, mutated_clone); assert_eq!( @@ -2285,9 +2289,9 @@ mod tests { "repeating the same propagation key should reuse the cached entry" ); - let other = cache.single(PauliType::X, 0, 0, &gates, &meas_pos, &tracked_ops); + let other = cache.single(PauliType::X, 0, 0, &gates, &meas_pos, &tracked_paulis); let other_fresh = - propagate_single_effect(PauliType::X, 0, 0, &gates, &meas_pos, &tracked_ops); + propagate_single_effect(PauliType::X, 0, 0, &gates, &meas_pos, &tracked_paulis); assert_eq!(other, other_fresh); assert_eq!(cache.len(), 2); } @@ -2867,10 +2871,10 @@ mod tests { } #[test] - fn test_catalog_keeps_observables_and_tracked_ops_distinct() { + fn test_catalog_keeps_observables_and_tracked_paulis_distinct() { let mut tc = TickCircuit::new(); tc.tick().h(&[QubitId(0)]); - tc.tracked_operator_labeled("tracked_z0", PauliString::z(0)); + tc.tracked_pauli_labeled("tracked_z0", PauliString::z(0)); tc.set_meta( "detectors", pecos_quantum::Attribute::String("[]".to_string()), @@ -2913,21 +2917,21 @@ mod tests { .unwrap(); assert_eq!(x_fault.affected_observables, Vec::::new()); - assert_eq!(x_fault.affected_tracked_ops, vec![0]); - assert_eq!(y_fault.affected_tracked_ops, vec![0]); - assert_eq!(z_fault.affected_tracked_ops, Vec::::new()); + assert_eq!(x_fault.affected_tracked_paulis, vec![0]); + assert_eq!(y_fault.affected_tracked_paulis, vec![0]); + assert_eq!(z_fault.affected_tracked_paulis, Vec::::new()); let configs: Vec<_> = catalog.fault_configurations(1).collect(); assert!( configs .iter() - .any(|config| config.affected_tracked_ops.as_slice() == [0] + .any(|config| config.affected_tracked_paulis.as_slice() == [0] && config.affected_observables.is_empty()) ); } #[test] - fn test_catalog_after_tick_dag_round_trip_keeps_outputs_and_tracked_ops_separate() { + fn test_catalog_after_tick_dag_round_trip_keeps_outputs_and_tracked_paulis_separate() { let mut tc = TickCircuit::new(); tc.tick().h(&[QubitId(0), QubitId(1)]); tc.tick().mz(&[QubitId(0)]); @@ -2939,13 +2943,13 @@ mod tests { .unwrap(); tc.add_observable_metadata(&[-1], Some(0), Some("L0")) .unwrap(); - tc.tracked_operator_labeled("tracked_z1", PauliString::z(1)); + tc.tracked_pauli_labeled("tracked_z1", PauliString::z(1)); let round_tripped = TickCircuit::from(&pecos_quantum::DagCircuit::from(&tc)); assert_eq!(round_tripped.annotations().len(), 1); assert!(matches!( round_tripped.annotations()[0].kind, - AnnotationKind::TrackedOperator + AnnotationKind::TrackedPauli )); let catalog = build_fault_catalog( @@ -2972,7 +2976,7 @@ mod tests { assert_eq!(x_fault.affected_measurements, vec![0]); assert_eq!(x_fault.affected_detectors, vec![0]); assert_eq!(x_fault.affected_observables, vec![0]); - assert!(x_fault.affected_tracked_ops.is_empty()); + assert!(x_fault.affected_tracked_paulis.is_empty()); let tracked_h_loc = catalog .locations @@ -2987,7 +2991,7 @@ mod tests { assert!(tracked_x_fault.affected_measurements.is_empty()); assert!(tracked_x_fault.affected_detectors.is_empty()); assert!(tracked_x_fault.affected_observables.is_empty()); - assert_eq!(tracked_x_fault.affected_tracked_ops, vec![0]); + assert_eq!(tracked_x_fault.affected_tracked_paulis, vec![0]); let meas_fault = catalog .locations @@ -2998,7 +3002,7 @@ mod tests { assert_eq!(meas_fault.affected_measurements, vec![0]); assert_eq!(meas_fault.affected_detectors, vec![0]); assert_eq!(meas_fault.affected_observables, vec![0]); - assert!(meas_fault.affected_tracked_ops.is_empty()); + assert!(meas_fault.affected_tracked_paulis.is_empty()); assert!(catalog.to_mechanisms().iter().any(|mechanism| { mechanism @@ -3010,7 +3014,7 @@ mod tests { #[test] fn test_catalog_two_qubit_propagation_keeps_output_kinds_distinct() { - fn assert_case(gate_type: GateType, tracked_op: PauliString) { + fn assert_case(gate_type: GateType, tracked_pauli: PauliString) { let mut tc = TickCircuit::new(); tc.tick().h(&[QubitId(0)]); match gate_type { @@ -3037,7 +3041,7 @@ mod tests { .unwrap(); tc.add_observable_metadata(&[-1], Some(0), Some("L0")) .unwrap(); - tc.tracked_operator_labeled("tracked", tracked_op); + tc.tracked_pauli_labeled("tracked", tracked_pauli); let catalog = build_fault_catalog( &tc, @@ -3064,7 +3068,7 @@ mod tests { assert_eq!(x_fault.affected_measurements, vec![0], "{gate_type:?}"); assert_eq!(x_fault.affected_detectors, vec![0], "{gate_type:?}"); assert_eq!(x_fault.affected_observables, vec![0], "{gate_type:?}"); - assert_eq!(x_fault.affected_tracked_ops, vec![0], "{gate_type:?}"); + assert_eq!(x_fault.affected_tracked_paulis, vec![0], "{gate_type:?}"); } // X0 before CX becomes X0 X1. @@ -3254,7 +3258,7 @@ mod tests { start: usize, gates: &[GateLoc], meas_positions: &HashMap, - tracked_ops: &[PauliString], + tracked_paulis: &[PauliString], ) -> PropagatedFaultEffect { let terms: Vec<_> = pauli .iter_pairs() @@ -3262,14 +3266,14 @@ mod tests { .collect(); match terms.as_slice() { [(p, q)] => { - propagate_single_effect(*p, *q, start, gates, meas_positions, tracked_ops) + propagate_single_effect(*p, *q, start, gates, meas_positions, tracked_paulis) } [(p0, q0), (p1, q1)] => propagate_pair_effect( [(*p0, *q0), (*p1, *q1)], start, gates, meas_positions, - tracked_ops, + tracked_paulis, ), other => panic!("expected one- or two-qubit Pauli alternative, got {other:?}"), } @@ -3289,12 +3293,12 @@ mod tests { .unwrap(); tc.add_observable_metadata(&[-1], Some(0), Some("L0")) .unwrap(); - tc.tracked_operator_labeled("tracked_x1", PauliString::x(1)); - tc.tracked_operator_labeled("tracked_y1", PauliString::y(1)); - tc.tracked_operator_labeled("tracked_z1", PauliString::z(1)); + tc.tracked_pauli_labeled("tracked_x1", PauliString::x(1)); + tc.tracked_pauli_labeled("tracked_y1", PauliString::y(1)); + tc.tracked_pauli_labeled("tracked_z1", PauliString::z(1)); let (gates, meas_positions) = flatten_tick_circuit(&tc); - let tracked_ops = parse_tracked_operator_annotations(&tc); + let tracked_paulis = parse_tracked_pauli_annotations(&tc); let catalog = build_fault_catalog( &tc, &StochasticNoiseParams { @@ -3325,7 +3329,7 @@ mod tests { source_loc_idx + 1, &gates, &meas_positions, - &tracked_ops, + &tracked_paulis, ); let measurements: Vec<_> = effect.affected_measurements.iter().copied().collect(); assert_eq!( @@ -3341,7 +3345,7 @@ mod tests { "{gate_type:?} {pauli:?}" ); assert_eq!( - fault.affected_tracked_ops, effect.affected_tracked_ops, + fault.affected_tracked_paulis, effect.affected_tracked_paulis, "{gate_type:?} {pauli:?}" ); } @@ -3366,15 +3370,15 @@ mod tests { .unwrap(); tc.add_observable_metadata(&[-1], Some(1), Some("L1")) .unwrap(); - tc.tracked_operator_labeled("tracked_x2", PauliString::x(2)); - tc.tracked_operator_labeled("tracked_y2", PauliString::y(2)); - tc.tracked_operator_labeled("tracked_z2", PauliString::z(2)); - tc.tracked_operator_labeled("tracked_x3", PauliString::x(3)); - tc.tracked_operator_labeled("tracked_y3", PauliString::y(3)); - tc.tracked_operator_labeled("tracked_z3", PauliString::z(3)); + tc.tracked_pauli_labeled("tracked_x2", PauliString::x(2)); + tc.tracked_pauli_labeled("tracked_y2", PauliString::y(2)); + tc.tracked_pauli_labeled("tracked_z2", PauliString::z(2)); + tc.tracked_pauli_labeled("tracked_x3", PauliString::x(3)); + tc.tracked_pauli_labeled("tracked_y3", PauliString::y(3)); + tc.tracked_pauli_labeled("tracked_z3", PauliString::z(3)); let (gates, meas_positions) = flatten_tick_circuit(&tc); - let tracked_ops = parse_tracked_operator_annotations(&tc); + let tracked_paulis = parse_tracked_pauli_annotations(&tc); let catalog = build_fault_catalog( &tc, &StochasticNoiseParams { @@ -3405,7 +3409,7 @@ mod tests { source_loc_idx + 1, &gates, &meas_positions, - &tracked_ops, + &tracked_paulis, ); let measurements: Vec<_> = effect.affected_measurements.iter().copied().collect(); assert_eq!( @@ -3421,7 +3425,7 @@ mod tests { "{gate_type:?} {pauli:?}" ); assert_eq!( - fault.affected_tracked_ops, effect.affected_tracked_ops, + fault.affected_tracked_paulis, effect.affected_tracked_paulis, "{gate_type:?} {pauli:?}" ); } @@ -3429,7 +3433,7 @@ mod tests { } #[test] - fn test_fault_configurations_xor_detectors_observables_and_tracked_ops_separately() { + fn test_fault_configurations_xor_detectors_observables_and_tracked_paulis_separately() { let mut tc = TickCircuit::new(); tc.tick().h(&[QubitId(0), QubitId(1)]); tc.tick().cx(&[(QubitId(0), QubitId(2))]); @@ -3442,7 +3446,7 @@ mod tests { .unwrap(); tc.add_observable_metadata(&[-2], Some(0), Some("L0")) .unwrap(); - tc.tracked_operator_labeled("tracked_z2", PauliString::z(2)); + tc.tracked_pauli_labeled("tracked_z2", PauliString::z(2)); let catalog = build_fault_catalog( &tc, @@ -3484,7 +3488,10 @@ mod tests { assert_eq!(catalog.locations[h0].faults[x0].affected_detectors, [0]); assert_eq!(catalog.locations[h0].faults[x0].affected_observables, [0]); - assert_eq!(catalog.locations[h0].faults[x0].affected_tracked_ops, [0]); + assert_eq!( + catalog.locations[h0].faults[x0].affected_tracked_paulis, + [0] + ); assert_eq!(catalog.locations[h1].faults[x1].affected_detectors, [0]); assert!( catalog.locations[h1].faults[x1] @@ -3493,22 +3500,22 @@ mod tests { ); assert!( catalog.locations[h1].faults[x1] - .affected_tracked_ops + .affected_tracked_paulis .is_empty() ); assert_eq!(config.affected_measurements, [0, 1]); assert!(config.affected_detectors.is_empty()); assert_eq!(config.affected_observables, [0]); - assert_eq!(config.affected_tracked_ops, [0]); + assert_eq!(config.affected_tracked_paulis, [0]); } #[test] - fn test_tracked_operator_phase_is_ignored_for_flip_tracking() { + fn test_tracked_pauli_phase_is_ignored_for_flip_tracking() { let mut tc = TickCircuit::new(); tc.tick().h(&[QubitId(0)]); - tc.tracked_operator_labeled("plus_z0", PauliString::z(0)); - tc.tracked_operator_labeled( + tc.tracked_pauli_labeled("plus_z0", PauliString::z(0)); + tc.tracked_pauli_labeled( "minus_z0", PauliString::with_phase_and_paulis( pecos_core::QuarterPhase::MinusOne, @@ -3516,14 +3523,14 @@ mod tests { ), ); - let tracked_ops = parse_tracked_operator_annotations(&tc); - assert_eq!(tracked_ops.len(), 2); + let tracked_paulis = parse_tracked_pauli_annotations(&tc); + assert_eq!(tracked_paulis.len(), 2); assert!( - tracked_ops + tracked_paulis .iter() .all(|op| op.phase() == pecos_core::QuarterPhase::PlusOne) ); - assert_eq!(tracked_ops[0], tracked_ops[1]); + assert_eq!(tracked_paulis[0], tracked_paulis[1]); let catalog = build_fault_catalog( &tc, @@ -3552,8 +3559,8 @@ mod tests { .find(|fault| fault.pauli.as_ref() == Some(&PauliString::z(0))) .unwrap(); - assert_eq!(x_fault.affected_tracked_ops, vec![0, 1]); - assert_eq!(z_fault.affected_tracked_ops, Vec::::new()); + assert_eq!(x_fault.affected_tracked_paulis, vec![0, 1]); + assert_eq!(z_fault.affected_tracked_paulis, Vec::::new()); } #[test] @@ -3655,7 +3662,7 @@ mod tests { assert_eq!(af.affected_measurements, bf.affected_measurements); assert_eq!(af.affected_detectors, bf.affected_detectors); assert_eq!(af.affected_observables, bf.affected_observables); - assert_eq!(af.affected_tracked_ops, bf.affected_tracked_ops); + assert_eq!(af.affected_tracked_paulis, bf.affected_tracked_paulis); assert_close(af.conditional_probability, bf.conditional_probability); assert_close(af.absolute_probability, bf.absolute_probability); } @@ -3785,7 +3792,7 @@ mod tests { fn test_tracked_only_effect_stays_in_catalog_but_not_raw_mechanisms() { let mut tc = TickCircuit::new(); tc.tick().h(&[QubitId(0)]); - tc.tracked_operator_labeled("tracked_z0", PauliString::z(0)); + tc.tracked_pauli_labeled("tracked_z0", PauliString::z(0)); let mut catalog = FaultCatalog::from_circuit(&tc).unwrap(); catalog.with_noise(&StochasticNoiseParams { @@ -3801,7 +3808,7 @@ mod tests { .find(|loc| loc.channel == FaultChannel::P1) .unwrap(); assert!(h_loc.faults.iter().any(|fault| { - fault.affected_measurements.is_empty() && !fault.affected_tracked_ops.is_empty() + fault.affected_measurements.is_empty() && !fault.affected_tracked_paulis.is_empty() })); assert!(catalog.to_mechanisms().is_empty()); } diff --git a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs index 8c4b956ba..aa77d8e71 100644 --- a/crates/pecos-qec/src/fault_tolerance/influence_builder.rs +++ b/crates/pecos-qec/src/fault_tolerance/influence_builder.rs @@ -51,7 +51,7 @@ struct ObservablePropagationWork<'a> { /// to create complete influence maps suitable for noisy sampling. /// Re-export `PauliString` as the type used for Pauli operator tracking. /// -/// All circuit annotations (detectors, observables, operators) are Pauli +/// All circuit annotations (detectors, observables, tracked Paulis) are Pauli /// strings tracked for flipping via backward propagation. The difference /// is role and readout: /// @@ -59,13 +59,13 @@ struct ObservablePropagationWork<'a> { /// |------|---------|---------|-----| /// | Detector | Syndrome parity from measurements | measurement XOR = 0 | `dag.detector(&[...])` | /// | Observable | Standard `L` output from measurements | measurement XOR | `dag.observable(&[...])` | -/// | Tracked operator | User Pauli operator annotated at a circuit point | fault anticommutes with operator | `dag.tracked_operator(&[...])` | +/// | Tracked Pauli | User Pauli string annotated at a circuit point | fault anticommutes with tracked Pauli | `dag.tracked_pauli(&[...])` | /// -/// Observables and tracked operators both use backward Pauli propagation, but +/// Observables and tracked Paulis both use backward Pauli propagation, but /// they are not the same concept. Observables are values observed through /// measurements, are defined by measurement records, and are decoder-visible -/// `L` outputs. Tracked operators are not measured and are not applied to the -/// computation; they ask whether a fault would flip a Pauli operator placed as +/// `L` outputs. Tracked Paulis are not measured and are not applied to the +/// computation; they ask whether a fault would flip the annotated Pauli placed as /// an annotation in the circuit, such as a logical operator, stabilizer, or /// other Pauli of interest. They live in a separate PECOS-only namespace. pub use pecos_core::PauliString; @@ -105,31 +105,31 @@ impl<'a> InfluenceBuilder<'a> { } } - /// Add a tracked X operator (X on all specified qubits). + /// Add a tracked X Pauli (X on all specified qubits). #[must_use] pub fn with_x(mut self, qubits: &[usize]) -> Self { self.push_single_term_output( - DemOutputMetadata::tracked_operator(PauliString::xs(qubits)), + DemOutputMetadata::tracked_pauli(PauliString::xs(qubits)), None, ); self } - /// Add a tracked Z operator (Z on all specified qubits). + /// Add a tracked Z Pauli (Z on all specified qubits). #[must_use] pub fn with_z(mut self, qubits: &[usize]) -> Self { self.push_single_term_output( - DemOutputMetadata::tracked_operator(PauliString::zs(qubits)), + DemOutputMetadata::tracked_pauli(PauliString::zs(qubits)), None, ); self } - /// Add a tracked Y operator (Y on all specified qubits). + /// Add a tracked Y Pauli (Y on all specified qubits). #[must_use] pub fn with_y(mut self, qubits: &[usize]) -> Self { self.push_single_term_output( - DemOutputMetadata::tracked_operator(PauliString::ys(qubits)), + DemOutputMetadata::tracked_pauli(PauliString::ys(qubits)), None, ); self @@ -149,14 +149,14 @@ impl<'a> InfluenceBuilder<'a> { /// use pecos_quantum::DagCircuit; /// /// let dag = DagCircuit::new(); - /// let builder = InfluenceBuilder::new(&dag).with_tracked_operator( + /// let builder = InfluenceBuilder::new(&dag).with_tracked_pauli( /// PauliString::from_paulis(&[Pauli::X, Pauli::Z, Pauli::Z]), /// ); /// let _map = builder.build(); /// ``` #[must_use] - pub fn with_tracked_operator(mut self, pauli: PauliString) -> Self { - self.push_single_term_output(DemOutputMetadata::tracked_operator(pauli), None); + pub fn with_tracked_pauli(mut self, pauli: PauliString) -> Self { + self.push_single_term_output(DemOutputMetadata::tracked_pauli(pauli), None); self } @@ -170,14 +170,14 @@ impl<'a> InfluenceBuilder<'a> { }); } - /// Extract observable and tracked-operator annotations from the circuit. + /// Extract observable and tracked-Pauli annotations from the circuit. /// /// Observable annotations define logical observables via measurement records. /// For backward propagation, each referenced measurement contributes its /// own Z-type propagation term starting at that measurement node. The terms /// accumulate into the same observable `L` output. /// - /// Tracked-operator annotations have a corresponding `PauliOperatorMeta` node + /// Tracked-Pauli annotations have a corresponding `TrackedPauliMeta` node /// that marks their time position. /// /// Detector annotations are NOT handled here -- they are processed @@ -185,8 +185,8 @@ impl<'a> InfluenceBuilder<'a> { /// to auto-detected detectors. #[must_use] pub fn with_circuit_annotations(mut self, circuit: &pecos_quantum::DagCircuit) -> Self { - // Find PauliOperatorMeta nodes in topological order. - // The nth meta-gate corresponds to the nth Operator annotation. + // Find TrackedPauliMeta nodes in topological order. + // The nth meta-gate corresponds to the nth tracked-Pauli annotation. let meta_nodes: Vec = circuit .topological_order() .into_iter() @@ -214,11 +214,11 @@ impl<'a> InfluenceBuilder<'a> { terms, }); } - pecos_quantum::AnnotationKind::TrackedOperator => { + pecos_quantum::AnnotationKind::TrackedPauli => { let meta_node = meta_nodes.get(operator_idx).copied(); operator_idx += 1; self.push_single_term_output( - DemOutputMetadata::tracked_operator(ann.pauli.clone()) + DemOutputMetadata::tracked_pauli(ann.pauli.clone()) .with_optional_label(ann.label.clone()), meta_node, ); @@ -1056,7 +1056,7 @@ mod tests { } #[test] - fn test_with_tracked_operator() { + fn test_with_tracked_pauli() { let mut dag = DagCircuit::new(); dag.pz(&[2]); dag.cx(&[(0, 2)]); @@ -1076,16 +1076,16 @@ mod tests { let pauli = PauliString::from_paulis_with_phase(QuarterPhase::MinusI, &[Pauli::X, Pauli::Z]); - let metadata = DemOutputMetadata::tracked_operator(pauli).with_label("xz"); + let metadata = DemOutputMetadata::tracked_pauli(pauli).with_label("xz"); - assert_eq!(metadata.kind, DemOutputKind::TrackedOperator); + assert_eq!(metadata.kind, DemOutputKind::TrackedPauli); assert_eq!(metadata.label.as_deref(), Some("xz")); assert_eq!(metadata.pauli.phase(), QuarterPhase::PlusOne); assert_eq!(metadata.pauli.to_sparse_str(), "+X0 Z1"); } #[test] - fn test_circuit_annotation_dem_output_metadata_tracks_observables_and_operators() { + fn test_circuit_annotation_dem_output_metadata_tracks_observables_and_tracked_paulis() { use pecos_core::pauli::X; let mut dag = DagCircuit::new(); @@ -1093,15 +1093,15 @@ mod tests { dag.h(&[0]); let meas = dag.mz(&[0]); dag.observable_labeled("record_obs", &[meas[0]]); - dag.tracked_operator_labeled("track_x", X(0)); + dag.tracked_pauli_labeled("track_x", X(0)); let map = InfluenceBuilder::new(&dag) .with_circuit_annotations(&dag) .build(); - // 1 observable (record_obs) + 1 tracked operator (track_x) = 2 DEM outputs + // 1 observable (record_obs) + 1 tracked Pauli (track_x) = 2 DEM outputs assert_eq!(map.num_dem_outputs(), 1, "1 observable"); - assert_eq!(map.num_tracked_ops(), 1, "1 tracked operator"); + assert_eq!(map.num_tracked_paulis(), 1, "1 tracked Pauli"); assert_eq!(map.dem_output_metadata.len(), 2); // Observable comes first (annotations are processed in order) @@ -1111,11 +1111,8 @@ mod tests { Some("record_obs") ); - // Tracked operator second - assert_eq!( - map.dem_output_metadata[1].kind, - DemOutputKind::TrackedOperator - ); + // Tracked Pauli second + assert_eq!(map.dem_output_metadata[1].kind, DemOutputKind::TrackedPauli); assert_eq!(map.dem_output_metadata[1].label.as_deref(), Some("track_x")); assert_eq!(map.dem_output_metadata[1].pauli.to_sparse_str(), "+X0"); } diff --git a/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs b/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs index 0ad232d1d..50d828465 100644 --- a/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs +++ b/crates/pecos-qec/src/fault_tolerance/lookup_decoder.rs @@ -478,17 +478,17 @@ mod tests { use pecos_quantum::DagCircuit; #[test] - fn observable_indices_use_compact_l_namespace_with_tracked_ops() { + fn observable_indices_use_compact_l_namespace_with_tracked_paulis() { let mut dag = DagCircuit::new(); dag.pz(&[0]); - dag.tracked_operator_labeled("track_x", X(0)); + dag.tracked_pauli_labeled("track_x", X(0)); let meas = dag.mz(&[0]); dag.observable_labeled("obs0", &[meas[0]]); let map = InfluenceBuilder::new(&dag) .with_circuit_annotations(&dag) .build(); - assert_eq!(map.num_tracked_ops(), 1); + assert_eq!(map.num_tracked_paulis(), 1); assert_eq!(map.num_observables(), 1); let decoder = LookupDecoder::build(&map, &NoiseConfig::uniform(0.01), 1); diff --git a/crates/pecos-qec/src/fault_tolerance/propagator.rs b/crates/pecos-qec/src/fault_tolerance/propagator.rs index aea82a9f6..e35bb7239 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator.rs @@ -48,9 +48,9 @@ //! let (has_syndrome, _flips_non_detector_output) = map.classify_fault(0, 1); // loc 0, X fault //! ``` //! -//! Observables and tracked operators are distinct. Observables are values +//! Observables and tracked Paulis are distinct. Observables are values //! observed through measurement-record parities and become standard `L` -//! outputs in DEM text. Tracked operators are Pauli operators annotated at +//! outputs in DEM text. Tracked Paulis are Pauli operators annotated at //! circuit points; they are not measured and are not applied to the computation. //! PECOS records whether each fault anticommutes with, and therefore would flip, //! the propagated operator. @@ -116,7 +116,7 @@ pub use tick::TickFaultAnalyzer; pub use tick_batched::TickFaultAnalyzerBatched; pub use types::{ DemOutputIdx, DetectorId, DetectorIdx, FaultInfluence, FaultInfluenceMap, LocationId, - MeasurementId, NodeId, Pauli, TrackedOpId, TrackedOpIdx, + MeasurementId, NodeId, Pauli, TrackedPauliId, TrackedPauliIdx, }; // Internal imports @@ -775,8 +775,10 @@ mod tests { // Get any fault location and check classification if let Some((loc, _)) = map.influences.iter().next() { - let (has_syndrome, flips_tracked_op) = checker.classify(loc, 1); // X fault - println!("Location {loc:?}: syndrome={has_syndrome}, tracked_op={flips_tracked_op}"); + let (has_syndrome, flips_tracked_pauli) = checker.classify(loc, 1); // X fault + println!( + "Location {loc:?}: syndrome={has_syndrome}, tracked_pauli={flips_tracked_pauli}" + ); } } @@ -959,35 +961,35 @@ mod tests { } #[test] - fn test_backward_vs_forward_with_tracked_ops() { - // Test that tracked-operator propagation works with backward propagation + fn test_backward_vs_forward_with_tracked_paulis() { + // Test that tracked-Pauli propagation works with backward propagation let mut circuit = TickCircuit::new(); circuit.tick().pz(&[0, 1, 2]); circuit.tick().cx(&[(0, 2)]); circuit.tick().cx(&[(1, 2)]); circuit.tick().mz(&[2]); - // Define a simple tracked Z operator = Z0 Z1 - let tracked_ops: &[(&[usize], &[usize])] = &[(&[], &[0, 1])]; + // Define a simple tracked Z Pauli = Z0 Z1 + let tracked_paulis: &[(&[usize], &[usize])] = &[(&[], &[0, 1])]; let propagator = TickFaultAnalyzer::new(&circuit); - let map = propagator.build_influence_map_with_tracked_ops(tracked_ops); + let map = propagator.build_influence_map_with_tracked_paulis(tracked_paulis); - // Check that tracked-operator propagation is populated - assert_eq!(map.tracked_ops.len(), 1); + // Check that tracked-Pauli propagation is populated + assert_eq!(map.tracked_paulis.len(), 1); - // X errors on data qubits should flip the tracked operator - let mut found_tracked_op_flip = false; + // X errors on data qubits should flip the tracked Pauli + let mut found_tracked_pauli_flip = false; for (loc, influence) in &map.influences { if loc.qubits.iter().any(|q| q.index() == 0 || q.index() == 1) - && !influence.tracked_ops_for_pauli(1).is_empty() + && !influence.tracked_paulis_for_pauli(1).is_empty() { - found_tracked_op_flip = true; + found_tracked_pauli_flip = true; } } assert!( - found_tracked_op_flip, - "Should find X errors that flip tracked operator" + found_tracked_pauli_flip, + "Should find X errors that flip tracked Pauli" ); } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/checker.rs b/crates/pecos-qec/src/fault_tolerance/propagator/checker.rs index 4f95cd5ca..6bc14be8f 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/checker.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/checker.rs @@ -36,11 +36,11 @@ impl<'a> InfluenceBasedChecker<'a> { /// Classifies a fault at the given location with the given Pauli type. /// /// For single-qubit locations, returns whether any qubit causes syndrome or - /// flips a tracked operator. + /// flips a tracked Pauli. /// For multi-qubit locations where the same Pauli is applied to all qubits, /// use `classify_uniform` which properly handles cancellation effects. /// - /// Returns (`has_syndrome`, `flips_tracked_op`). + /// Returns (`has_syndrome`, `flips_tracked_pauli`). #[must_use] pub fn classify(&self, location: &SpacetimeLocation, pauli: u8) -> (bool, bool) { self.influence_map.classify_fault(location, pauli) @@ -54,7 +54,7 @@ impl<'a> InfluenceBasedChecker<'a> { /// For Y faults (single or multi-qubit), we decompose Y = XZ and combine the /// X and Z contributions with XOR semantics. /// - /// Returns (`has_syndrome`, `flips_tracked_op`). + /// Returns (`has_syndrome`, `flips_tracked_pauli`). #[must_use] pub fn classify_uniform(&self, location: &SpacetimeLocation, pauli: u8) -> (bool, bool) { // Always use multi-qubit logic for Y faults (even single-qubit) @@ -78,10 +78,10 @@ impl<'a> InfluenceBasedChecker<'a> { }) } - /// Checks if a fault silently flips a tracked operator. + /// Checks if a fault silently flips a tracked Pauli. #[must_use] - pub fn is_silent_tracked_op_flip(&self, location: &SpacetimeLocation, pauli: u8) -> bool { - let (has_syndrome, flips_tracked_op) = self.classify(location, pauli); - !has_syndrome && flips_tracked_op + pub fn is_silent_tracked_pauli_flip(&self, location: &SpacetimeLocation, pauli: u8) -> bool { + let (has_syndrome, flips_tracked_pauli) = self.classify(location, pauli); + !has_syndrome && flips_tracked_pauli } } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs b/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs index 6551a7326..99d164f04 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/dag.rs @@ -37,15 +37,15 @@ //! The influence map has one detector namespace plus one raw internal //! non-detector-output namespace. That raw namespace is only a storage detail: //! metadata maps each raw non-detector output to either a standard observable -//! (`L`) or a PECOS tracked operator. Decoder and sampler code should use +//! (`L`) or a PECOS tracked Pauli. Decoder and sampler code should use //! [`DagFaultInfluenceMap::observable_ids`], //! [`DagFaultInfluenceMap::observable_id_for_internal_dem_output`], and -//! [`DagFaultInfluenceMap::tracked_op_id_for_internal_dem_output`] instead of +//! [`DagFaultInfluenceMap::tracked_pauli_id_for_internal_dem_output`] instead of //! assuming raw indices are public `L` IDs. //! -//! Observables and tracked operators differ by definition, not just by name. +//! Observables and tracked Paulis differ by definition, not just by name. //! Observables are values observed through measurement-record parities and are -//! visible to DEM decoders as standard `L` outputs. Tracked operators are +//! visible to DEM decoders as standard `L` outputs. Tracked Paulis are //! unmeasured Pauli operators annotated at a circuit point, such as logical //! operators, stabilizers, or other Paulis of interest; the influence map //! records whether a fault anticommutes with, and therefore would flip, the @@ -382,7 +382,7 @@ pub struct InfluencesSoA { /// /// These raw indices may name either standard observables or PECOS tracked /// operators. Use [`DagFaultInfluenceMap`] metadata helpers to map them into - /// the public `L` observable namespace or tracked-operator namespace. + /// the public `L` observable namespace or tracked-Pauli namespace. pub dem_outputs_x: CsrArray, /// Internal non-detector output indices flipped by Y faults. @@ -426,8 +426,8 @@ impl InfluencesSoA { /// These indices are not necessarily standard `L` IDs. Callers that /// need public observable IDs should use /// [`DagFaultInfluenceMap::observable_id_for_internal_dem_output`]; callers - /// that need tracked-operator IDs should use - /// [`DagFaultInfluenceMap::tracked_op_id_for_internal_dem_output`]. + /// that need tracked-Pauli IDs should use + /// [`DagFaultInfluenceMap::tracked_pauli_id_for_internal_dem_output`]. #[inline] #[must_use] pub fn dem_outputs(&self, loc_idx: usize, pauli: Pauli) -> &[u32] { @@ -522,8 +522,8 @@ impl InfluencesSoA { /// Returns the maximum raw non-detector output influence index, if any. /// /// When metadata is present, callers should use [`Self::num_dem_outputs`] - /// for the standard observable `L` namespace and [`Self::num_tracked_ops`] - /// for PECOS tracked operators. + /// for the standard observable `L` namespace and [`Self::num_tracked_paulis`] + /// for PECOS tracked Paulis. #[must_use] pub fn max_dem_output_index(&self) -> Option { let max_x = self.dem_outputs_x.data.iter().max(); @@ -585,10 +585,10 @@ pub struct DagFaultInfluenceMap { /// Optional metadata for non-detector outputs tracked by backward propagation. /// - /// These entries may be standard observables or PECOS tracked operators. + /// These entries may be standard observables or PECOS tracked Paulis. /// The metadata kind is the authority for translating raw influence indices /// into public namespaces; standard observables use compact `L` IDs and - /// tracked operators use their own compact PECOS-only IDs. + /// tracked Paulis use their own compact PECOS-only IDs. pub dem_output_metadata: Vec, } @@ -626,8 +626,8 @@ impl DagFaultInfluenceMap { /// Returns all raw non-detector output indices flipped by a fault. /// /// Raw indices are an internal storage detail shared by observables and - /// tracked operators. Prefer [`Self::get_observable_indices`] or - /// [`Self::get_tracked_op_indices`] when a public namespace is needed. + /// tracked Paulis. Prefer [`Self::get_observable_indices`] or + /// [`Self::get_tracked_pauli_indices`] when a public namespace is needed. #[inline] #[must_use] pub fn get_dem_output_indices(&self, loc_idx: usize, pauli: u8) -> &[u32] { @@ -637,7 +637,7 @@ impl DagFaultInfluenceMap { /// Returns the number of standard DEM `L` observable outputs. /// /// This is a DEM-output alias for [`Self::num_observables`]. It does - /// not include PECOS tracked operators. + /// not include PECOS tracked Paulis. #[must_use] pub fn num_dem_outputs(&self) -> usize { if self.dem_output_metadata.is_empty() { @@ -657,7 +657,7 @@ impl DagFaultInfluenceMap { /// Returns the standard observable `L` IDs present in this map. /// - /// Tracked operators share internal propagation storage but never appear in + /// Tracked Paulis share internal propagation storage but never appear in /// this set. Public decoder and sampler paths should use this namespace /// rather than raw internal DEM-output indices. #[must_use] @@ -667,22 +667,22 @@ impl DagFaultInfluenceMap { .collect() } - /// Returns the number of PECOS tracked operators. + /// Returns the number of PECOS tracked Paulis. #[must_use] - pub fn num_tracked_ops(&self) -> usize { + pub fn num_tracked_paulis(&self) -> usize { self.dem_output_metadata .iter() - .filter(|metadata| metadata.kind == DemOutputKind::TrackedOperator) + .filter(|metadata| metadata.kind == DemOutputKind::TrackedPauli) .count() } - /// Returns tracked-Pauli-operator output indices flipped by a fault. + /// Returns tracked-Pauli output indices flipped by a fault. #[must_use] - pub fn get_tracked_op_indices(&self, loc_idx: usize, pauli: u8) -> Vec { + pub fn get_tracked_pauli_indices(&self, loc_idx: usize, pauli: u8) -> Vec { let outputs = self.get_dem_output_indices(loc_idx, pauli); outputs .iter() - .filter_map(|&idx| self.tracked_op_id_for_internal_dem_output(idx)) + .filter_map(|&idx| self.tracked_pauli_id_for_internal_dem_output(idx)) .collect() } @@ -709,11 +709,11 @@ impl DagFaultInfluenceMap { self.output_id_for_kind(idx, DemOutputKind::Observable) } - /// Map an internal non-detector output index to the PECOS tracked-operator + /// Map an internal non-detector output index to the PECOS tracked-Pauli /// ID space. #[must_use] - pub fn tracked_op_id_for_internal_dem_output(&self, idx: u32) -> Option { - self.output_id_for_kind(idx, DemOutputKind::TrackedOperator) + pub fn tracked_pauli_id_for_internal_dem_output(&self, idx: u32) -> Option { + self.output_id_for_kind(idx, DemOutputKind::TrackedPauli) } /// Returns true if a fault flips any non-detector DEM output. @@ -723,10 +723,10 @@ impl DagFaultInfluenceMap { !self.get_dem_output_indices(loc_idx, pauli).is_empty() } - /// Returns true if a fault flips any tracked Pauli operator. + /// Returns true if a fault flips any tracked Pauli. #[must_use] - pub fn has_tracked_op_flips(&self, loc_idx: usize, pauli: u8) -> bool { - !self.get_tracked_op_indices(loc_idx, pauli).is_empty() + pub fn has_tracked_pauli_flips(&self, loc_idx: usize, pauli: u8) -> bool { + !self.get_tracked_pauli_indices(loc_idx, pauli).is_empty() } /// Returns true if a fault flips any observable. @@ -794,9 +794,9 @@ impl DagFaultInfluenceMap { /// Export CSR data for GPU use. /// /// The exported DEM-output arrays contain only standard observable `L` - /// outputs. PECOS tracked operators share the internal backward-propagation + /// outputs. PECOS tracked Paulis share the internal backward-propagation /// storage but are intentionally filtered out here so decoder-oriented GPU - /// code cannot count tracked operators as logical errors. + /// code cannot count tracked Paulis as logical errors. /// /// Returns all CSR arrays needed to construct a GPU influence sampler: /// (`num_locations`, `num_detectors`, `num_dem_outputs`, @@ -900,7 +900,7 @@ pub enum DemOutputKind { /// A standard `L` observable defined by measurement records. Observable, /// An unmeasured Pauli-operator annotation, separate from measurement records. - TrackedOperator, + TrackedPauli, } impl DemOutputKind { @@ -909,7 +909,7 @@ impl DemOutputKind { pub const fn as_str(self) -> &'static str { match self { Self::Observable => "observable", - Self::TrackedOperator => "tracked_operator", + Self::TrackedPauli => "tracked_pauli", } } @@ -918,7 +918,7 @@ impl DemOutputKind { pub fn from_metadata_str(kind: &str) -> Option { match kind { "observable" => Some(Self::Observable), - "tracked_operator" => Some(Self::TrackedOperator), + "tracked_pauli" => Some(Self::TrackedPauli), _ => None, } } @@ -928,7 +928,7 @@ impl DemOutputKind { /// /// Standard DEM text only has `L` observable markers. PECOS keeps this richer /// record alongside the DEM so callers can distinguish those measurement-record -/// observables from tracked Pauli operators, which live in a separate +/// observables from tracked Paulis, which live in a separate /// PECOS-only namespace. #[derive(Debug, Clone, PartialEq, Eq)] pub struct DemOutputMetadata { @@ -937,7 +937,7 @@ pub struct DemOutputMetadata { /// Pauli string whose flip is tracked. /// /// For observables this is the Pauli associated with the measurement-record - /// observable. For tracked operators this is the unmeasured Pauli operator + /// observable. For tracked Paulis this is the unmeasured tracked Pauli /// annotated at a circuit point. pub pauli: PauliString, /// Optional user label. @@ -954,10 +954,10 @@ impl DemOutputMetadata { Self { kind, pauli, label } } - /// Creates metadata for a tracked operator. + /// Creates metadata for a tracked Pauli. #[must_use] - pub fn tracked_operator(pauli: PauliString) -> Self { - Self::new(DemOutputKind::TrackedOperator, pauli, None) + pub fn tracked_pauli(pauli: PauliString) -> Self { + Self::new(DemOutputKind::TrackedPauli, pauli, None) } /// Creates metadata for an observable. @@ -2713,7 +2713,7 @@ mod tests { } #[test] - fn test_export_csr_filters_tracked_operators_from_dem_outputs() { + fn test_export_csr_filters_tracked_paulis_from_dem_outputs() { let mut dag = DagCircuit::new(); dag.pz(&[0]); dag.h(&[0]); @@ -2723,10 +2723,10 @@ mod tests { .build(); assert_eq!(map.num_dem_outputs(), 0); - assert_eq!(map.num_tracked_ops(), 1); + assert_eq!(map.num_tracked_paulis(), 1); assert!( map.influences.max_dem_output_index().is_some(), - "tracked operator should still use internal propagation storage" + "tracked Pauli should still use internal propagation storage" ); let ( @@ -2767,9 +2767,9 @@ mod tests { idle_duration: 0, }); map.dem_output_metadata = vec![ - DemOutputMetadata::tracked_operator(pecos_core::PauliString::xs(&[0])), + DemOutputMetadata::tracked_pauli(pecos_core::PauliString::xs(&[0])), DemOutputMetadata::observable(pecos_core::PauliString::zs(&[0])), - DemOutputMetadata::tracked_operator(pecos_core::PauliString::zs(&[1])), + DemOutputMetadata::tracked_pauli(pecos_core::PauliString::zs(&[1])), ]; map.influences.dem_outputs_x.extend([0, 1, 2]); @@ -2782,9 +2782,12 @@ mod tests { map.influences.num_locations = 1; assert_eq!(map.num_dem_outputs(), 1); - assert_eq!(map.num_tracked_ops(), 2); + assert_eq!(map.num_tracked_paulis(), 2); assert_eq!(map.get_observable_indices(0, Pauli::X.as_u8()), vec![0]); - assert_eq!(map.get_tracked_op_indices(0, Pauli::X.as_u8()), vec![0, 1]); + assert_eq!( + map.get_tracked_pauli_indices(0, Pauli::X.as_u8()), + vec![0, 1] + ); let ( _num_locations, diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs b/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs index 3a94fc0bf..7e75427b5 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/tick.rs @@ -18,7 +18,7 @@ //! For better performance, consider using [`DagFaultAnalyzer`](super::DagFaultAnalyzer) //! with DAG circuits, which provides 5-50x speedup through sparse traversal. -use super::types::{DetectorId, FaultInfluence, FaultInfluenceMap, MeasurementId, TrackedOpId}; +use super::types::{DetectorId, FaultInfluence, FaultInfluenceMap, MeasurementId, TrackedPauliId}; use super::{Direction, SpacetimeLocation, apply_gate, extract_spacetime_locations}; use pecos_core::gate_type::GateType; use pecos_quantum::TickCircuit; @@ -85,20 +85,20 @@ impl<'a> TickFaultAnalyzer<'a> { /// creates a lookup table for fault classification. #[must_use] pub fn build_influence_map(&self) -> FaultInfluenceMap { - self.build_influence_map_with_tracked_ops(&[]) + self.build_influence_map_with_tracked_paulis(&[]) } - /// Builds the fault influence map with tracked Pauli operator tracking. + /// Builds the fault influence map with tracked Pauli tracking. /// /// # Arguments /// - /// * `tracked_ops` - Tracked Pauli operators as (`x_positions`, `z_positions`) pairs. + /// * `tracked_paulis` - Tracked Paulis as (`x_positions`, `z_positions`) pairs. /// The first element of each pair is the X component positions, /// the second is the Z component positions. #[must_use] - pub fn build_influence_map_with_tracked_ops( + pub fn build_influence_map_with_tracked_paulis( &self, - tracked_ops: &[(&[usize], &[usize])], + tracked_paulis: &[(&[usize], &[usize])], ) -> FaultInfluenceMap { let mut map = FaultInfluenceMap::new(); @@ -112,9 +112,9 @@ impl<'a> TickFaultAnalyzer<'a> { map.detectors.push(DetectorId::single(*m)); } - // Create tracked-operator IDs - for (i, _) in tracked_ops.iter().enumerate() { - map.tracked_ops.push(TrackedOpId { + // Create tracked-Pauli IDs + for (i, _) in tracked_paulis.iter().enumerate() { + map.tracked_paulis.push(TrackedPauliId { op_index: i, component: 0, }); @@ -131,13 +131,13 @@ impl<'a> TickFaultAnalyzer<'a> { self.propagate_from_measurement(measurement, &mut map); } - // Backward propagate from each tracked Pauli operator - for (i, (x_pos, z_pos)) in tracked_ops.iter().enumerate() { - let tracked_op_id = TrackedOpId { + // Backward propagate from each tracked Pauli + for (i, (x_pos, z_pos)) in tracked_paulis.iter().enumerate() { + let tracked_pauli_id = TrackedPauliId { op_index: i, component: 0, }; - self.propagate_from_tracked_op(x_pos, z_pos, &tracked_op_id, &mut map); + self.propagate_from_tracked_pauli(x_pos, z_pos, &tracked_pauli_id, &mut map); } // Build reverse maps @@ -259,37 +259,37 @@ impl<'a> TickFaultAnalyzer<'a> { } } - /// Propagates backward from a tracked Pauli operator. + /// Propagates backward from a tracked Pauli. /// - /// We propagate the tracked operator backward through the circuit. An error + /// We propagate the tracked Pauli backward through the circuit. An error /// P at location L flips it if P anticommutes with the back-propagated /// operator at L. /// /// This uses sparse traversal: only gates touching qubits with non-trivial /// Paulis are processed, providing significant speedup for circuits with /// local connectivity. - fn propagate_from_tracked_op( + fn propagate_from_tracked_pauli( &self, x_positions: &[usize], z_positions: &[usize], - tracked_op_id: &TrackedOpId, + tracked_pauli_id: &TrackedPauliId, map: &mut FaultInfluenceMap, ) { - // Start with the tracked operator itself (not swapped) + // Start with the tracked Pauli itself (not swapped) // The recording function handles anticommutation checking let mut prop = PauliProp::new(); // Track active qubits for sparse traversal let mut active_qubits = vec![false; self.max_qubit + 1]; - // X positions in tracked op -> X in prop + // X positions in tracked Pauli -> X in prop for &q in x_positions { prop.track_x(&[q]); if q <= self.max_qubit { active_qubits[q] = true; } } - // Z positions in tracked op -> Z in prop + // Z positions in tracked Pauli -> Z in prop for &q in z_positions { prop.track_z(&[q]); if q <= self.max_qubit { @@ -312,7 +312,7 @@ impl<'a> TickFaultAnalyzer<'a> { tick_idx, &prop, &dummy_detector, - Some(tracked_op_id), + Some(tracked_pauli_id), map, false, ); @@ -345,7 +345,7 @@ impl<'a> TickFaultAnalyzer<'a> { tick_idx, &prop, &dummy_detector, - Some(tracked_op_id), + Some(tracked_pauli_id), map, true, ); @@ -368,7 +368,7 @@ impl<'a> TickFaultAnalyzer<'a> { tick_idx: usize, prop: &PauliProp, detector: &DetectorId, - tracked_op: Option<&TrackedOpId>, + tracked_pauli: Option<&TrackedPauliId>, map: &mut FaultInfluenceMap, only_before: bool, ) { @@ -400,8 +400,8 @@ impl<'a> TickFaultAnalyzer<'a> { // X fault anticommutes with Z or Y observable let x_flips = obs_z; // Z or Y (both have Z component) if x_flips { - if let Some(op) = tracked_op { - influence.tracked_op_flips[1].push(*op); + if let Some(op) = tracked_pauli { + influence.tracked_pauli_flips[1].push(*op); } else { influence.detector_flips[1].push(detector.clone()); influence.measurement_flips[1] @@ -419,8 +419,8 @@ impl<'a> TickFaultAnalyzer<'a> { // (Z anticommutes with X, Z anticommutes with Y=iXZ) let z_flips = obs_x; // X or Y (both have X component) if z_flips { - if let Some(op) = tracked_op { - influence.tracked_op_flips[3].push(*op); + if let Some(op) = tracked_pauli { + influence.tracked_pauli_flips[3].push(*op); } else { influence.detector_flips[3].push(detector.clone()); influence.measurement_flips[3] @@ -437,8 +437,8 @@ impl<'a> TickFaultAnalyzer<'a> { // Y fault: Y anticommutes with X or Z but NOT both (Y commutes with Y) let y_flips = obs_x ^ obs_z; if y_flips { - if let Some(op) = tracked_op { - influence.tracked_op_flips[2].push(*op); + if let Some(op) = tracked_pauli { + influence.tracked_pauli_flips[2].push(*op); } else { influence.detector_flips[2].push(detector.clone()); influence.measurement_flips[2] @@ -485,7 +485,7 @@ impl<'a> TickFaultAnalyzer<'a> { apply_gate(prop, gate, Direction::Backward); } - /// Builds reverse maps (detector -> faults, tracked operator -> faults). + /// Builds reverse maps (detector -> faults, tracked Pauli -> faults). fn build_reverse_maps(map: &mut FaultInfluenceMap) { for (loc, influence) in &map.influences { for (pauli, detectors) in influence.detector_flips.iter().enumerate() { @@ -499,12 +499,12 @@ impl<'a> TickFaultAnalyzer<'a> { } } - for (pauli, tracked_ops) in influence.tracked_op_flips.iter().enumerate() { + for (pauli, tracked_paulis) in influence.tracked_pauli_flips.iter().enumerate() { #[allow(clippy::cast_possible_truncation)] // Pauli index 0..2 let pauli_u8 = pauli as u8; - for tracked_op in tracked_ops { - map.tracked_op_to_faults - .entry(*tracked_op) + for tracked_pauli in tracked_paulis { + map.tracked_pauli_to_faults + .entry(*tracked_pauli) .or_default() .push((loc.clone(), pauli_u8)); } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/tick_batched.rs b/crates/pecos-qec/src/fault_tolerance/propagator/tick_batched.rs index 3884d8e95..388a53ec8 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/tick_batched.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/tick_batched.rs @@ -12,7 +12,7 @@ //! 4. **Direct array access**: Skips Option-returning methods in hot loops use super::SpacetimeLocation; -use super::types::{DetectorId, FaultInfluence, FaultInfluenceMap, MeasurementId, TrackedOpId}; +use super::types::{DetectorId, FaultInfluence, FaultInfluenceMap, MeasurementId, TrackedPauliId}; use pecos_core::{QubitId, gate_type::GateType}; use pecos_quantum::TickCircuit; use pecos_simulators::{CliffordGateable, PauliProp}; @@ -178,14 +178,14 @@ impl<'a> TickFaultAnalyzerBatched<'a> { /// Builds the complete fault influence map. #[must_use] pub fn build_influence_map(&self) -> FaultInfluenceMap { - self.build_influence_map_with_tracked_ops(&[]) + self.build_influence_map_with_tracked_paulis(&[]) } - /// Builds the fault influence map with tracked Pauli operator tracking. + /// Builds the fault influence map with tracked Pauli tracking. #[must_use] - pub fn build_influence_map_with_tracked_ops( + pub fn build_influence_map_with_tracked_paulis( &self, - tracked_ops: &[(&[usize], &[usize])], + tracked_paulis: &[(&[usize], &[usize])], ) -> FaultInfluenceMap { let mut map = FaultInfluenceMap::new(); @@ -198,9 +198,9 @@ impl<'a> TickFaultAnalyzerBatched<'a> { map.detectors.push(DetectorId::single(*m)); } - // Create tracked-operator IDs - for (i, _) in tracked_ops.iter().enumerate() { - map.tracked_ops.push(TrackedOpId { + // Create tracked-Pauli IDs + for (i, _) in tracked_paulis.iter().enumerate() { + map.tracked_paulis.push(TrackedPauliId { op_index: i, component: 0, }); @@ -222,16 +222,16 @@ impl<'a> TickFaultAnalyzerBatched<'a> { self.propagate_from_measurement_optimized(measurement, &mut map, &mut buffers); } - // Backward propagate from each tracked Pauli operator - for (i, (x_pos, z_pos)) in tracked_ops.iter().enumerate() { - let tracked_op_id = TrackedOpId { + // Backward propagate from each tracked Pauli + for (i, (x_pos, z_pos)) in tracked_paulis.iter().enumerate() { + let tracked_pauli_id = TrackedPauliId { op_index: i, component: 0, }; - self.propagate_from_tracked_op_optimized( + self.propagate_from_tracked_pauli_optimized( x_pos, z_pos, - &tracked_op_id, + &tracked_pauli_id, &mut map, &mut buffers, ); @@ -547,12 +547,12 @@ impl<'a> TickFaultAnalyzerBatched<'a> { } } - /// Optimized backward propagation from a tracked Pauli operator. - fn propagate_from_tracked_op_optimized( + /// Optimized backward propagation from a tracked Pauli. + fn propagate_from_tracked_pauli_optimized( &self, x_positions: &[usize], z_positions: &[usize], - tracked_op_id: &TrackedOpId, + tracked_pauli_id: &TrackedPauliId, map: &mut FaultInfluenceMap, buffers: &mut AnalyzerWorkBuffers, ) { @@ -585,7 +585,7 @@ impl<'a> TickFaultAnalyzerBatched<'a> { tick_idx, &prop, &dummy_detector, - Some(tracked_op_id), + Some(tracked_pauli_id), map, false, ); @@ -596,7 +596,7 @@ impl<'a> TickFaultAnalyzerBatched<'a> { tick_idx, &prop, &dummy_detector, - Some(tracked_op_id), + Some(tracked_pauli_id), map, true, ); @@ -610,7 +610,7 @@ impl<'a> TickFaultAnalyzerBatched<'a> { tick_idx: usize, prop: &PauliProp, detector: &DetectorId, - tracked_op: Option<&TrackedOpId>, + tracked_pauli: Option<&TrackedPauliId>, map: &mut FaultInfluenceMap, only_before: bool, ) { @@ -634,8 +634,8 @@ impl<'a> TickFaultAnalyzerBatched<'a> { if let Some(influence) = map.influences.get_mut(loc) { // X fault anticommutes with Z or Y observable if obs_z { - if let Some(op) = tracked_op { - influence.tracked_op_flips[1].push(*op); + if let Some(op) = tracked_pauli { + influence.tracked_pauli_flips[1].push(*op); } else { influence.detector_flips[1].push(detector.clone()); influence.measurement_flips[1] @@ -650,8 +650,8 @@ impl<'a> TickFaultAnalyzerBatched<'a> { // Z fault anticommutes with X or Y observable if obs_x { - if let Some(op) = tracked_op { - influence.tracked_op_flips[3].push(*op); + if let Some(op) = tracked_pauli { + influence.tracked_pauli_flips[3].push(*op); } else { influence.detector_flips[3].push(detector.clone()); influence.measurement_flips[3] @@ -666,8 +666,8 @@ impl<'a> TickFaultAnalyzerBatched<'a> { // Y fault: anticommutes with X or Z but NOT both (Y commutes with Y) if obs_x ^ obs_z { - if let Some(op) = tracked_op { - influence.tracked_op_flips[2].push(*op); + if let Some(op) = tracked_pauli { + influence.tracked_pauli_flips[2].push(*op); } else { influence.detector_flips[2].push(detector.clone()); influence.measurement_flips[2] @@ -698,12 +698,12 @@ impl<'a> TickFaultAnalyzerBatched<'a> { } } - for (pauli, tracked_ops) in influence.tracked_op_flips.iter().enumerate() { + for (pauli, tracked_paulis) in influence.tracked_pauli_flips.iter().enumerate() { #[allow(clippy::cast_possible_truncation)] // Pauli index 0..2 let pauli_u8 = pauli as u8; - for tracked_op in tracked_ops { - map.tracked_op_to_faults - .entry(*tracked_op) + for tracked_pauli in tracked_paulis { + map.tracked_pauli_to_faults + .entry(*tracked_pauli) .or_default() .push((loc.clone(), pauli_u8)); } @@ -750,7 +750,7 @@ mod tests { } #[test] - fn test_tracked_op_propagation() { + fn test_tracked_pauli_propagation() { let mut circuit = TickCircuit::new(); circuit.tick().pz(&[0, 1]); circuit.tick().h(&[0]); @@ -758,9 +758,9 @@ mod tests { circuit.tick().mz(&[0, 1]); let analyzer = TickFaultAnalyzerBatched::new(&circuit); - let tracked_ops = [(&[] as &[usize], &[1usize] as &[usize])]; - let map = analyzer.build_influence_map_with_tracked_ops(&tracked_ops); + let tracked_paulis = [(&[] as &[usize], &[1usize] as &[usize])]; + let map = analyzer.build_influence_map_with_tracked_paulis(&tracked_paulis); - assert_eq!(map.tracked_ops.len(), 1); + assert_eq!(map.tracked_paulis.len(), 1); } } diff --git a/crates/pecos-qec/src/fault_tolerance/propagator/types.rs b/crates/pecos-qec/src/fault_tolerance/propagator/types.rs index fd01ffe6c..a7d6673c0 100644 --- a/crates/pecos-qec/src/fault_tolerance/propagator/types.rs +++ b/crates/pecos-qec/src/fault_tolerance/propagator/types.rs @@ -154,14 +154,14 @@ impl From for usize { #[repr(transparent)] pub struct DemOutputIdx(pub u32); -/// A PECOS tracked-operator metadata index. +/// A PECOS tracked-Pauli metadata index. /// -/// This is intentionally separate from [`DemOutputIdx`]: tracked operators are +/// This is intentionally separate from [`DemOutputIdx`]: tracked Paulis are /// not standard DEM `L` targets and should not be handed to decoders as /// logical observables. #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)] #[repr(transparent)] -pub struct TrackedOpIdx(pub u32); +pub struct TrackedPauliIdx(pub u32); impl DemOutputIdx { #[inline] @@ -198,7 +198,7 @@ impl From for usize { } } -impl TrackedOpIdx { +impl TrackedPauliIdx { #[inline] #[must_use] pub const fn new(index: u32) -> Self { @@ -213,22 +213,22 @@ impl TrackedOpIdx { #[inline] #[must_use] - #[allow(clippy::cast_possible_truncation)] // tracked-op index fits in u32 + #[allow(clippy::cast_possible_truncation)] // tracked-Pauli index fits in u32 pub const fn from_usize(index: usize) -> Self { Self(index as u32) } } -impl From for TrackedOpIdx { +impl From for TrackedPauliIdx { #[inline] fn from(index: usize) -> Self { Self::from_usize(index) } } -impl From for usize { +impl From for usize { #[inline] - fn from(id: TrackedOpIdx) -> Self { + fn from(id: TrackedPauliIdx) -> Self { id.index() } } @@ -331,10 +331,10 @@ impl DetectorId { } } -/// Unique identifier for a tracked Pauli operator in the older tick influence map. +/// Unique identifier for a tracked Pauli in the older tick influence map. #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] -pub struct TrackedOpId { - /// Index of the tracked operator. +pub struct TrackedPauliId { + /// Index of the tracked Pauli. pub op_index: usize, /// Optional Pauli component marker for callers that split X/Z components. pub component: u8, @@ -349,8 +349,8 @@ pub struct FaultInfluence { /// Index 0 is unused (identity fault has no effect). pub detector_flips: [Vec; 4], - /// Which tracked Pauli operators this fault flips, indexed by Pauli type. - pub tracked_op_flips: [Vec; 4], + /// Which tracked Paulis this fault flips, indexed by Pauli type. + pub tracked_pauli_flips: [Vec; 4], /// Which raw measurements this fault flips, indexed by Pauli type. pub measurement_flips: [Vec; 4], @@ -365,7 +365,7 @@ impl FaultInfluence { #[must_use] pub fn is_trivial(&self) -> bool { self.detector_flips.iter().all(std::vec::Vec::is_empty) - && self.tracked_op_flips.iter().all(std::vec::Vec::is_empty) + && self.tracked_pauli_flips.iter().all(std::vec::Vec::is_empty) && self.measurement_flips.iter().all(std::vec::Vec::is_empty) } @@ -378,11 +378,11 @@ impl FaultInfluence { .map_or(&[], |v| v.as_slice()) } - /// Returns all tracked Pauli operators flipped by a specific Pauli type. + /// Returns all tracked Paulis flipped by a specific Pauli type. #[inline] #[must_use] - pub fn tracked_ops_for_pauli(&self, pauli: u8) -> &[TrackedOpId] { - self.tracked_op_flips + pub fn tracked_paulis_for_pauli(&self, pauli: u8) -> &[TrackedPauliId] { + self.tracked_pauli_flips .get(pauli as usize) .map_or(&[], |v| v.as_slice()) } @@ -400,8 +400,8 @@ pub struct FaultInfluenceMap { /// All detectors in the circuit. pub detectors: Vec, - /// All tracked Pauli operators. - pub tracked_ops: Vec, + /// All tracked Paulis. + pub tracked_paulis: Vec, /// All measurements in the circuit. pub measurements: Vec, @@ -409,8 +409,8 @@ pub struct FaultInfluenceMap { /// Reverse map: for each detector, which fault locations flip it. pub detector_to_faults: BTreeMap>, - /// Reverse map: for each tracked Pauli operator, which fault locations flip it. - pub tracked_op_to_faults: BTreeMap>, + /// Reverse map: for each tracked Pauli, which fault locations flip it. + pub tracked_pauli_to_faults: BTreeMap>, } impl FaultInfluenceMap { @@ -420,10 +420,10 @@ impl FaultInfluenceMap { Self { influences: BTreeMap::new(), detectors: Vec::new(), - tracked_ops: Vec::new(), + tracked_paulis: Vec::new(), measurements: Vec::new(), detector_to_faults: BTreeMap::new(), - tracked_op_to_faults: BTreeMap::new(), + tracked_pauli_to_faults: BTreeMap::new(), } } @@ -435,14 +435,14 @@ impl FaultInfluenceMap { /// Quickly classifies a single-qubit fault based on pre-computed influences. /// - /// Returns (`has_syndrome`, `flips_tracked_op`) for the given Pauli type. + /// Returns (`has_syndrome`, `flips_tracked_pauli`) for the given Pauli type. /// For multi-qubit locations, use `classify_multi_qubit_fault` instead. #[must_use] pub fn classify_fault(&self, location: &SpacetimeLocation, pauli: u8) -> (bool, bool) { if let Some(influence) = self.influences.get(location) { let has_syndrome = !influence.detectors_for_pauli(pauli).is_empty(); - let flips_tracked_op = !influence.tracked_ops_for_pauli(pauli).is_empty(); - (has_syndrome, flips_tracked_op) + let flips_tracked_pauli = !influence.tracked_paulis_for_pauli(pauli).is_empty(); + (has_syndrome, flips_tracked_pauli) } else { (false, false) } @@ -457,7 +457,7 @@ impl FaultInfluenceMap { /// For Y faults, we decompose Y = XZ and combine the X and Z contributions, /// since Y anticommutes with both X and Z components of the observable. /// - /// Returns (`has_syndrome`, `flips_tracked_op`). + /// Returns (`has_syndrome`, `flips_tracked_pauli`). #[must_use] pub fn classify_multi_qubit_fault( &self, @@ -502,11 +502,11 @@ impl FaultInfluenceMap { // Syndrome = odd number of flips for any detector let has_syndrome = detector_flip_counts.values().any(|&count| count % 2 == 1); - // For tracked operators, use the same approach + // For tracked Paulis, use the same approach // (simplified: just check if any component flips, proper handling TBD) - let flips_tracked_op = !influence.tracked_ops_for_pauli(pauli).is_empty(); + let flips_tracked_pauli = !influence.tracked_paulis_for_pauli(pauli).is_empty(); - (has_syndrome, flips_tracked_op) + (has_syndrome, flips_tracked_pauli) } else { (false, false) } diff --git a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs index b7af4b999..9df5a9356 100644 --- a/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs +++ b/crates/pecos-qec/src/fault_tolerance/targeted_lookup_decoder.rs @@ -393,7 +393,7 @@ mod tests { affected_measurements: Vec::new(), affected_detectors: vec![0], affected_observables: vec![9], - affected_tracked_ops: Vec::new(), + affected_tracked_paulis: Vec::new(), conditional_probability: 1.0, absolute_probability: 0.0, }], @@ -413,7 +413,7 @@ mod tests { affected_measurements: vec![0], affected_detectors: vec![0], affected_observables: Vec::new(), - affected_tracked_ops: Vec::new(), + affected_tracked_paulis: Vec::new(), conditional_probability: 1.0, absolute_probability: 0.1, }], @@ -431,7 +431,7 @@ mod tests { } #[test] - fn test_decode_ignores_tracked_operator_effects() { + fn test_decode_ignores_tracked_pauli_effects() { let catalog = FaultCatalog { locations: vec![ FaultLocation { @@ -449,7 +449,7 @@ mod tests { affected_measurements: Vec::new(), affected_detectors: vec![0], affected_observables: vec![1], - affected_tracked_ops: vec![0], + affected_tracked_paulis: vec![0], conditional_probability: 1.0, absolute_probability: 0.2, }], @@ -469,7 +469,7 @@ mod tests { affected_measurements: Vec::new(), affected_detectors: vec![0], affected_observables: Vec::new(), - affected_tracked_ops: vec![3], + affected_tracked_paulis: vec![3], conditional_probability: 1.0, absolute_probability: 0.1, }], diff --git a/crates/pecos-qec/tests/fault_enumeration_example.rs b/crates/pecos-qec/tests/fault_enumeration_example.rs index 83edb2498..eb2010a1a 100644 --- a/crates/pecos-qec/tests/fault_enumeration_example.rs +++ b/crates/pecos-qec/tests/fault_enumeration_example.rs @@ -16,7 +16,7 @@ //! Example: Repetition code d=3 with 3 rounds of syndrome extraction. //! //! Demonstrates the full QEC workflow: -//! 1. Build the circuit with annotations (detectors, observables, Pauli operators) +//! 1. Build the circuit with annotations (detectors, observables, tracked Paulis) //! 2. Build the fault influence map //! 3. Enumerate fault combinations up to weight 3 //! 4. Classify errors (detectable, undetectable, logical) @@ -99,7 +99,7 @@ fn build_repetition_code(num_rounds: usize) -> DagCircuit { dag.observable_labeled("logical_Z", &[ms_data[0]]); // Pauli operator: track logical X = X_0 X_1 X_2 - dag.tracked_operator_labeled("logical_X", X(0) & X(1) & X(2)); + dag.tracked_pauli_labeled("logical_X", X(0) & X(1) & X(2)); dag } @@ -114,7 +114,7 @@ fn repetition_code_fault_enumeration() { let kind = match &ann.kind { pecos_quantum::AnnotationKind::Detector { .. } => "detector", pecos_quantum::AnnotationKind::Observable { .. } => "observable", - pecos_quantum::AnnotationKind::TrackedOperator => "tracked_operator", + pecos_quantum::AnnotationKind::TrackedPauli => "tracked_pauli", }; let label = ann.label.as_deref().unwrap_or("(none)"); println!(" {kind:10} {label:15} {}", ann.pauli); @@ -289,12 +289,12 @@ fn repetition_code_labels() { .with_circuit_annotations(&dag) .build(); - // Check DEM-output labels are populated (observables + tracked ops) + // Check DEM-output labels are populated (observables + tracked Paulis) println!("DEM output labels: {:?}", map.dem_output_labels); - // 1 observable (logical_Z) + 1 tracked operator (logical_X) = 2 labels + // 1 observable (logical_Z) + 1 tracked Pauli (logical_X) = 2 labels assert_eq!(map.dem_output_labels.len(), 2); assert_eq!(map.num_dem_outputs(), 1, "1 observable"); - assert_eq!(map.num_tracked_ops(), 1, "1 tracked operator"); + assert_eq!(map.num_tracked_paulis(), 1, "1 tracked Pauli"); // Labels accessible via internal index assert_eq!(map.dem_output_label(0), Some("logical_Z")); @@ -608,11 +608,11 @@ fn build_422_code(num_rounds: usize) -> DagCircuit { // Logical Z_2 = Z_0 Z_2 dag.observable_labeled("logical_Z2", &[ms_data[0], ms_data[2]]); - // Pauli operators: logical X operators + // Tracked Paulis: logical X operators // Logical X_1 = X_0 X_2 - dag.tracked_operator_labeled("logical_X1", X(0) & X(2)); + dag.tracked_pauli_labeled("logical_X1", X(0) & X(2)); // Logical X_2 = X_0 X_1 - dag.tracked_operator_labeled("logical_X2", X(0) & X(1)); + dag.tracked_pauli_labeled("logical_X2", X(0) & X(1)); dag } @@ -628,7 +628,7 @@ fn code_422_fault_enumeration() { let kind = match &ann.kind { pecos_quantum::AnnotationKind::Detector { .. } => "detector", pecos_quantum::AnnotationKind::Observable { .. } => "observable", - pecos_quantum::AnnotationKind::TrackedOperator => "tracked_operator", + pecos_quantum::AnnotationKind::TrackedPauli => "tracked_pauli", }; let label = ann.label.as_deref().unwrap_or("(none)"); println!(" {kind:10} {label:15} {}", ann.pauli); diff --git a/crates/pecos-qec/tests/targeted_tests.rs b/crates/pecos-qec/tests/targeted_tests.rs index 4cd32bd7f..610be7b27 100644 --- a/crates/pecos-qec/tests/targeted_tests.rs +++ b/crates/pecos-qec/tests/targeted_tests.rs @@ -283,9 +283,9 @@ fn detector_derives_pauli_from_measurements() { assert_eq!(paulis[1].0, pecos_core::Pauli::Z); } -/// Verify `tracked_operator` normalizes phase to +1. +/// Verify `tracked_pauli` normalizes phase to +1. #[test] -fn tracked_operator_normalizes_phase() { +fn tracked_pauli_normalizes_phase() { let mut dag = DagCircuit::new(); dag.pz(&[0]); @@ -293,7 +293,7 @@ fn tracked_operator_normalizes_phase() { let neg_x = -X(0); assert_ne!(neg_x.get_phase(), pecos_core::QuarterPhase::PlusOne); - dag.tracked_operator(neg_x); + dag.tracked_pauli(neg_x); // After storage, phase should be normalized to +1 let ann = &dag.annotations()[0]; diff --git a/crates/pecos-qec/tests/unified_sampler_tests.rs b/crates/pecos-qec/tests/unified_sampler_tests.rs index 525e73cb9..3bdaa2c57 100644 --- a/crates/pecos-qec/tests/unified_sampler_tests.rs +++ b/crates/pecos-qec/tests/unified_sampler_tests.rs @@ -66,7 +66,7 @@ fn from_influence_map_produces_reasonable_statistics() { let stats = sampler.sample_statistics(num_shots, seed); // At these noise levels, we should see some syndromes. The builder above - // uses `with_z`, which creates a tracked operator, not an observable, so + // uses `with_z`, which creates a tracked Pauli, not an observable, so // logical-error statistics and DEM output columns stay empty. assert!( stats.syndrome_rate() > 0.0, @@ -77,7 +77,7 @@ fn from_influence_map_produces_reasonable_statistics() { "Should not have syndromes on every shot" ); assert_eq!(sampler.num_observables(), 0); - assert_eq!(sampler.num_tracked_ops(), 1); + assert_eq!(sampler.num_tracked_paulis(), 1); assert_eq!(stats.logical_error_count, 0); assert!(stats.dem_output_counts().is_empty()); } diff --git a/crates/pecos-quantum/src/circuit_display.rs b/crates/pecos-quantum/src/circuit_display.rs index fe13ef9e0..63a2b69fc 100644 --- a/crates/pecos-quantum/src/circuit_display.rs +++ b/crates/pecos-quantum/src/circuit_display.rs @@ -76,7 +76,7 @@ fn gate_symbol(gate_type: GateType) -> &'static str { GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload => "XT", GateType::Channel => "Ch", GateType::Custom => "?", - GateType::PauliOperatorMeta => "PO", + GateType::TrackedPauliMeta => "TP", } } @@ -221,7 +221,7 @@ fn gate_color(gate_type: GateType) -> CellColor { | GateType::R1XY | GateType::RXXRYYRZZ | GateType::U2q - | GateType::PauliOperatorMeta => CellColor::None, + | GateType::TrackedPauliMeta => CellColor::None, } } diff --git a/crates/pecos-quantum/src/dag_circuit.rs b/crates/pecos-quantum/src/dag_circuit.rs index 04a48ff2e..7086a6dcf 100644 --- a/crates/pecos-quantum/src/dag_circuit.rs +++ b/crates/pecos-quantum/src/dag_circuit.rs @@ -394,19 +394,19 @@ pub enum AnnotationKind { /// Logical observable: the Pauli's flip determines a logical outcome. /// Stores measurement node indices for classical readout via XOR. Observable { measurement_nodes: Vec }, - /// Tracked operator: no measurement readout. - /// Position is determined by a `PauliOperatorMeta` node in the DAG. - TrackedOperator, + /// Tracked Pauli: no measurement readout. + /// Position is determined by a `TrackedPauliMeta` node in the DAG. + TrackedPauli, } -/// A unified Pauli annotation: detectors, observables, and tracked operators +/// A unified Pauli annotation: detectors, observables, and tracked Paulis /// are all Pauli strings tracked for flipping via backward propagation. /// /// - **Detectors** are stabilizer checks that should be +1 (noiseless). /// Their Pauli is Z on the measured qubits. /// - **Observables** are logical operators read out via measurements. /// Their Pauli is Z on the measured qubits. -/// - **Tracked operators** are arbitrary Pauli strings with no measurement readout. +/// - **Tracked Paulis** are arbitrary Pauli strings with no measurement readout. /// Their Pauli is user-specified and their position comes from a meta-gate node. #[derive(Debug, Clone)] pub struct PauliAnnotation { @@ -432,7 +432,7 @@ pub struct DagCircuit { last_node: Option, /// Maximum qubit index seen so far (updated incrementally on gate addition). max_qubit: usize, - /// Unified Pauli annotations (detectors, observables, and tracked operators). + /// Unified Pauli annotations (detectors, observables, and tracked Paulis). annotations: Vec, /// Measurement labels (`node_index` → label). measurement_labels: BTreeMap, @@ -1757,10 +1757,10 @@ impl DagCircuit { pecos_core::PauliString::zs(&qubits) } - /// Place a tracked-operator meta-gate at this point in the circuit. + /// Place a tracked-Pauli meta-gate at this point in the circuit. /// /// This is a **positional** annotation: only faults BEFORE this node - /// can flip the tracked operator. The meta-gate does not affect quantum state + /// can flip the tracked Pauli. The meta-gate does not affect quantum state /// -- simulators ignore it. /// /// Accepts a [`PauliString`](pecos_core::PauliString), which supports @@ -1777,24 +1777,24 @@ impl DagCircuit { /// c.pz(&[0, 1, 2]); /// c.cx(&[(0, 1)]); /// // Place X_0 & Z_1 & Z_2 check HERE -- only faults above can flip it - /// c.tracked_operator(X(0) & Z(1) & Z(2)); + /// c.tracked_pauli(X(0) & Z(1) & Z(2)); /// c.cx(&[(1, 2)]); // faults here don't affect the check /// ``` - pub fn tracked_operator(&mut self, mut pauli: pecos_core::PauliString) -> usize { + pub fn tracked_pauli(&mut self, mut pauli: pecos_core::PauliString) -> usize { // Phase is irrelevant for flip tracking -- normalize to +1 pauli.set_phase(pecos_core::QuarterPhase::PlusOne); let idx = self.annotations.len(); self.insert_pauli_meta_gate(&pauli); self.annotations.push(PauliAnnotation { pauli, - kind: AnnotationKind::TrackedOperator, + kind: AnnotationKind::TrackedPauli, label: None, }); idx } - /// Place a labeled tracked-operator meta-gate. - pub fn tracked_operator_labeled( + /// Place a labeled tracked-Pauli meta-gate. + pub fn tracked_pauli_labeled( &mut self, label: &str, mut pauli: pecos_core::PauliString, @@ -1804,16 +1804,16 @@ impl DagCircuit { self.insert_pauli_meta_gate(&pauli); self.annotations.push(PauliAnnotation { pauli, - kind: AnnotationKind::TrackedOperator, + kind: AnnotationKind::TrackedPauli, label: Some(label.to_string()), }); idx } - /// Insert a `PauliOperatorMeta` gate node into the DAG. + /// Insert a `TrackedPauliMeta` gate node into the DAG. fn insert_pauli_meta_gate(&mut self, pauli: &pecos_core::PauliString) { let qubits: Vec = pauli.qubits().into_iter().map(QubitId::from).collect(); - let gate = Gate::simple(GateType::PauliOperatorMeta, qubits); + let gate = Gate::simple(GateType::TrackedPauliMeta, qubits); self.add_gate_auto_wire(gate); } @@ -1825,8 +1825,8 @@ impl DagCircuit { /// Add a pre-built annotation (used for conversion from `TickCircuit`). pub fn add_annotation(&mut self, ann: PauliAnnotation) { - // For tracked-operator annotations, insert the meta-gate node. - if matches!(ann.kind, AnnotationKind::TrackedOperator) { + // For tracked-Pauli annotations, insert the meta-gate node. + if matches!(ann.kind, AnnotationKind::TrackedPauli) { self.insert_pauli_meta_gate(&ann.pauli); } self.annotations.push(ann); @@ -1846,11 +1846,11 @@ impl DagCircuit { .filter(|a| matches!(a.kind, AnnotationKind::Observable { .. })) } - /// Get tracked-operator annotations. - pub fn tracked_operators(&self) -> impl Iterator { + /// Get tracked-Pauli annotations. + pub fn tracked_paulis(&self) -> impl Iterator { self.annotations .iter() - .filter(|a| matches!(a.kind, AnnotationKind::TrackedOperator)) + .filter(|a| matches!(a.kind, AnnotationKind::TrackedPauli)) } // ======================================================================== diff --git a/crates/pecos-quantum/src/pass.rs b/crates/pecos-quantum/src/pass.rs index 51e3e6870..98160d49b 100644 --- a/crates/pecos-quantum/src/pass.rs +++ b/crates/pecos-quantum/src/pass.rs @@ -1292,6 +1292,7 @@ impl CircuitPass for AssignMissingMeasIds { #[allow(clippy::cast_precision_loss)] mod tests { use super::*; + use pecos_core::MeasId; // ==================== simplify_rotation unit tests ==================== @@ -2884,6 +2885,78 @@ mod tests { assert!(saw_untouched); } + #[test] + fn split_batched_tick_commands_preserves_payloads_attrs_and_counters() { + let mut tc = TickCircuit::new(); + let initial_refs = tc.tick().mz(&[0, 1]); + assert_eq!(initial_refs[0].record_idx, 0); + assert_eq!(initial_refs[1].record_idx, 1); + tc.get_tick_mut(0).unwrap().set_gate_attr( + 0, + "role", + Attribute::String("measurement".into()), + ); + tc.tick() + .cx(&[(2, 3), (4, 5)]) + .meta("role", Attribute::String("entangler".into())); + + split_batched_tick_commands(&mut tc); + + assert_eq!(tc.num_ticks(), 2); + assert_eq!(tc.next_tick_index(), 2); + assert_eq!(tc.num_measurements(), 2); + + let meas_tick = tc.get_tick(0).unwrap(); + assert_eq!(meas_tick.len(), 2); + assert_eq!(meas_tick.gate_count(), 2); + assert_eq!( + meas_tick.gate_batches()[0].qubits.as_slice(), + &[QubitId::from(0)] + ); + assert_eq!( + meas_tick.gate_batches()[0].meas_ids.as_slice(), + &[MeasId(0)] + ); + assert_eq!( + meas_tick.gate_batches()[1].qubits.as_slice(), + &[QubitId::from(1)] + ); + assert_eq!( + meas_tick.gate_batches()[1].meas_ids.as_slice(), + &[MeasId(1)] + ); + for batch in meas_tick.iter_gate_batches() { + assert_eq!( + batch.get_attr("role"), + Some(&Attribute::String("measurement".into())) + ); + } + + let entangler_tick = tc.get_tick(1).unwrap(); + assert_eq!(entangler_tick.len(), 2); + assert_eq!(entangler_tick.gate_count(), 2); + assert_eq!( + entangler_tick.gate_batches()[0].qubits.as_slice(), + &[QubitId::from(2), QubitId::from(3)] + ); + assert_eq!( + entangler_tick.gate_batches()[1].qubits.as_slice(), + &[QubitId::from(4), QubitId::from(5)] + ); + for batch in entangler_tick.iter_gate_batches() { + assert_eq!( + batch.get_attr("role"), + Some(&Attribute::String("entangler".into())) + ); + } + + let later_refs = tc.tick().mz(&[6]); + assert_eq!(later_refs[0].record_idx, 2); + assert_eq!(later_refs[0].meas_id, MeasId(2)); + assert_eq!(tc.next_tick_index(), 3); + assert_eq!(tc.num_measurements(), 3); + } + #[test] fn peephole_tick_multiple_patterns() { // Two independent H-CX-H patterns diff --git a/crates/pecos-quantum/src/tick_circuit.rs b/crates/pecos-quantum/src/tick_circuit.rs index fcdd0a07c..dbfc3ed8b 100644 --- a/crates/pecos-quantum/src/tick_circuit.rs +++ b/crates/pecos-quantum/src/tick_circuit.rs @@ -2225,25 +2225,21 @@ impl TickCircuit { idx } - /// Place a tracked-operator annotation. - pub fn tracked_operator(&mut self, mut pauli: pecos_core::PauliString) -> usize { + /// Place a tracked-Pauli annotation. + pub fn tracked_pauli(&mut self, mut pauli: pecos_core::PauliString) -> usize { pauli.set_phase(pecos_core::QuarterPhase::PlusOne); let idx = self.annotations.len(); self.annotations.push(PauliAnnotation { pauli, - kind: AnnotationKind::TrackedOperator, + kind: AnnotationKind::TrackedPauli, label: None, }); idx } - /// Place a labeled tracked-operator annotation. - pub fn tracked_operator_labeled( - &mut self, - label: &str, - pauli: pecos_core::PauliString, - ) -> usize { - let idx = self.tracked_operator(pauli); + /// Place a labeled tracked-Pauli annotation. + pub fn tracked_pauli_labeled(&mut self, label: &str, pauli: pecos_core::PauliString) -> usize { + let idx = self.tracked_pauli(pauli); self.annotations[idx].label = Some(label.to_string()); idx } @@ -3225,7 +3221,7 @@ impl From<&DagCircuit> for TickCircuit { } // Transfer annotations, remapping DAG measurement nodes to TickCircuit - // measurement record indices. Tracked operators have no measurement + // measurement record indices. Tracked Paulis have no measurement // readout and keep their Pauli role unchanged. tc.annotations = dag .annotations() @@ -3250,7 +3246,7 @@ impl From<&DagCircuit> for TickCircuit { ), } } - AnnotationKind::TrackedOperator => AnnotationKind::TrackedOperator, + AnnotationKind::TrackedPauli => AnnotationKind::TrackedPauli, }; PauliAnnotation { pauli: ann.pauli.clone(), @@ -3397,7 +3393,7 @@ impl From<&TickCircuit> for DagCircuit { measurement_nodes: dag_nodes, } } - AnnotationKind::TrackedOperator => AnnotationKind::TrackedOperator, + AnnotationKind::TrackedPauli => AnnotationKind::TrackedPauli, }; dag.add_annotation(PauliAnnotation { pauli: ann.pauli.clone(), @@ -4381,7 +4377,7 @@ mod tests { } #[test] - fn test_detector_observable_and_tracked_operator_remain_distinct_after_round_trip() { + fn test_detector_observable_and_tracked_pauli_remain_distinct_after_round_trip() { use pecos_core::pauli::{X, Z}; let mut tc1 = TickCircuit::new(); @@ -4389,7 +4385,7 @@ mod tests { let ms = tc1.tick().mz(&[0, 1]); tc1.detector_labeled("detector", &[ms[0]]); tc1.observable_labeled("observable", &[ms[1]]); - tc1.tracked_operator_labeled("tracked", X(0) & Z(2)); + tc1.tracked_pauli_labeled("tracked", X(0) & Z(2)); let tc2 = TickCircuit::from(&DagCircuit::from(&tc1)); assert_eq!(tc2.annotations().len(), 3); @@ -4413,7 +4409,7 @@ mod tests { assert_eq!(tc2.annotations()[2].label.as_deref(), Some("tracked")); assert!(matches!( tc2.annotations()[2].kind, - AnnotationKind::TrackedOperator + AnnotationKind::TrackedPauli )); assert_eq!(tc2.annotations()[2].pauli, X(0) & Z(2)); } @@ -4532,7 +4528,7 @@ mod tests { tc1.detector_labeled(&format!("det-{case_idx}"), &detector_records); tc1.observable_labeled(&format!("obs-{case_idx}"), &observable_records); - tc1.tracked_operator_labeled(&format!("track-{case_idx}"), tracked.clone()); + tc1.tracked_pauli_labeled(&format!("track-{case_idx}"), tracked.clone()); let tc2 = TickCircuit::from(&DagCircuit::from(&tc1)); assert_eq!(tc2.gate_count(), tc1.gate_count(), "case {case_idx}"); @@ -4572,7 +4568,7 @@ mod tests { } let track = annotation_by_label(&tc2, &format!("track-{case_idx}")); - assert!(matches!(track.kind, AnnotationKind::TrackedOperator)); + assert!(matches!(track.kind, AnnotationKind::TrackedPauli)); assert_eq!(track.pauli, tracked, "case {case_idx}"); } } @@ -4644,7 +4640,7 @@ mod tests { let ms = tc1.tick().mz(&[70, 71]); tc1.detector_labeled("det-all-gates", &[ms[0]]); tc1.observable_labeled("obs-all-gates", &[ms[1]]); - tc1.tracked_operator_labeled("tracked-all-gates", X(70) & Z(71)); + tc1.tracked_pauli_labeled("tracked-all-gates", X(70) & Z(71)); let tc2 = TickCircuit::from(&DagCircuit::from(&tc1)); @@ -4673,7 +4669,7 @@ mod tests { )); assert!(matches!( tc2.annotations()[2].kind, - AnnotationKind::TrackedOperator + AnnotationKind::TrackedPauli )); assert!(tc2.has_channel_operations()); } @@ -4847,7 +4843,7 @@ mod tests { } else { Y(base + 2) }; - tc1.tracked_operator_labeled(&format!("tracked-{case_idx}"), tracked.clone()); + tc1.tracked_pauli_labeled(&format!("tracked-{case_idx}"), tracked.clone()); let tc2 = TickCircuit::from(&DagCircuit::from(&tc1)); @@ -4889,7 +4885,7 @@ mod tests { )); assert!(matches!( tc2.annotations()[2].kind, - AnnotationKind::TrackedOperator + AnnotationKind::TrackedPauli )); assert_eq!(tc2.annotations()[2].pauli, tracked, "case {case_idx}"); assert!(tc2.has_channel_operations(), "case {case_idx}"); @@ -5332,11 +5328,78 @@ mod tests { assert_eq!(counts.get(&GateType::MZ), Some(&4)); } + #[test] + fn test_gate_instance_to_gate_preserves_payloads_without_attrs() { + let angle = Angle64::from_turn_ratio(1, 8); + let mut rzz_tick = Tick::new(); + rzz_tick.add_gate(Gate::rzz(angle, &[(0, 1), (2, 3)])); + rzz_tick.set_gate_attr(0, "calibration", Attribute::String("rzz-cal".into())); + + let rzz_instances: Vec<_> = rzz_tick.iter_gate_instances().collect(); + assert_eq!(rzz_instances.len(), 2); + assert_eq!( + rzz_instances[0].get_attr("calibration"), + Some(&Attribute::String("rzz-cal".into())) + ); + assert_eq!( + rzz_instances[0].attrs().count(), + 1, + "batch metadata remains available through the instance view" + ); + assert_eq!(rzz_instances[0].angles(), &[angle]); + assert_eq!( + rzz_instances[0].to_gate(), + Gate::rzz(angle, &[(0usize, 1usize)]), + "materialized gates carry sliced support and payload, not attrs" + ); + assert_eq!( + rzz_instances[1].to_gate(), + Gate::rzz(angle, &[(2usize, 3usize)]) + ); + + let duration = 8.0_f64; + let mut idle_tick = Tick::new(); + idle_tick.add_gate(Gate::idle( + duration, + vec![QubitId::from(4), QubitId::from(5)], + )); + let idle_instances: Vec<_> = idle_tick.iter_gate_instances().collect(); + assert_eq!(idle_instances.len(), 2); + let idle_gate = idle_instances[1].to_gate(); + assert_eq!(idle_gate.gate_type, GateType::Idle); + assert_eq!(idle_gate.qubits.as_slice(), &[QubitId::from(5)]); + assert_eq!(idle_gate.params.len(), 1); + assert_eq!(idle_gate.params[0].to_bits(), duration.to_bits()); + + let mut meas_tc = TickCircuit::new(); + meas_tc.tick().mz(&[8, 9]); + let meas_instances: Vec<_> = meas_tc.get_tick(0).unwrap().iter_gate_instances().collect(); + assert_eq!(meas_instances.len(), 2); + assert_eq!( + meas_instances[0].to_gate().meas_ids.as_slice(), + &[MeasId(0)] + ); + assert_eq!( + meas_instances[1].to_gate().meas_ids.as_slice(), + &[MeasId(1)] + ); + + let channel = pecos_core::channel::Depolarizing(0.125, 6); + let mut channel_tick = Tick::new(); + channel_tick.add_gate(Gate::channel(channel.clone())); + let channel_instances: Vec<_> = channel_tick.iter_gate_instances().collect(); + assert_eq!(channel_instances.len(), 1); + let channel_gate = channel_instances[0].to_gate(); + assert_eq!(channel_gate.gate_type, GateType::Channel); + assert_eq!(channel_gate.qubits.as_slice(), &[QubitId::from(6)]); + assert_eq!(channel_gate.channel.as_ref(), Some(&channel)); + } + #[test] fn test_gate_instance_iteration_skips_annotation_batches() { let mut tick = Tick::new(); tick.add_gate(Gate::simple( - GateType::PauliOperatorMeta, + GateType::TrackedPauliMeta, vec![QubitId::from(0), QubitId::from(1)], )); @@ -5346,6 +5409,36 @@ mod tests { assert_eq!(tick.iter_gate_instances().count(), 0); } + #[test] + fn test_tick_to_dag_keeps_zero_gate_metadata_nodes_from_gate_count() { + let mut tc = TickCircuit::new(); + tc.tick().h(&[0]); + tc.tick(); + tc.get_tick_mut(1).unwrap().add_gate(Gate::simple( + GateType::TrackedPauliMeta, + vec![QubitId::from(1), QubitId::from(2)], + )); + tc.tick().mz(&[0]); + + let dag = DagCircuit::from(&tc); + + assert_eq!( + dag.gate_count(), + 2, + "metadata nodes are not gate applications" + ); + let metadata_nodes: Vec<_> = dag + .nodes() + .into_iter() + .filter(|&node| { + dag.gate(node) + .is_some_and(|gate| gate.gate_type == GateType::TrackedPauliMeta) + }) + .collect(); + assert_eq!(metadata_nodes.len(), 1); + assert_eq!(dag.gate(metadata_nodes[0]).unwrap().num_gates(), 0); + } + #[test] fn test_clear() { let mut tc = TickCircuit::new(); @@ -5391,7 +5484,7 @@ mod tests { let first_measurement = tc.tick().mz(&[0]); tc.detector(&first_measurement); tc.observable(&first_measurement); - tc.tracked_operator(pecos_core::pauli::Z(0)); + tc.tracked_pauli(pecos_core::pauli::Z(0)); assert_eq!(tc.num_measurements(), 1); assert_eq!(tc.annotations().len(), 3); @@ -5914,7 +6007,7 @@ mod tests { tc.detector_labeled("Z_check", &ms); tc.observable_labeled("logical_Z", &ms); - tc.tracked_operator_labeled("logical_X", X(0) & X(1)); + tc.tracked_pauli_labeled("logical_X", X(0) & X(1)); assert_eq!(tc.annotations().len(), 3); assert_eq!(tc.annotations()[0].label.as_deref(), Some("Z_check")); @@ -5933,7 +6026,7 @@ mod tests { let ms = tc.tick().mz(&[2]); tc.detector_labeled("det0", &ms); tc.observable_labeled("obs0", &ms); - tc.tracked_operator_labeled("op0", Z(0) & Z(1)); + tc.tracked_pauli_labeled("op0", Z(0) & Z(1)); let dag = DagCircuit::from(&tc); @@ -5954,7 +6047,7 @@ mod tests { )); assert!(matches!( dag.annotations()[2].kind, - crate::dag_circuit::AnnotationKind::TrackedOperator + crate::dag_circuit::AnnotationKind::TrackedPauli )); } @@ -5968,7 +6061,7 @@ mod tests { let ms = dag.mz(&[0, 1]); dag.detector_labeled("d0", &[ms[0]]); dag.observable_labeled("o0", &[ms[0], ms[1]]); - dag.tracked_operator_labeled("p0", X(0) & X(1)); + dag.tracked_pauli_labeled("p0", X(0) & X(1)); let tc = TickCircuit::from(&dag); @@ -5991,7 +6084,7 @@ mod tests { tc1.detector_labeled("syndr", &ms); let ms_data = tc1.tick().mz(&[0, 1]); tc1.observable_labeled("log_Z", &ms_data); - tc1.tracked_operator_labeled("log_X", X(0) & X(1)); + tc1.tracked_pauli_labeled("log_X", X(0) & X(1)); // TickCircuit -> DagCircuit -> TickCircuit let dag = DagCircuit::from(&tc1); diff --git a/crates/pecos-quantum/src/unitary_matrix.rs b/crates/pecos-quantum/src/unitary_matrix.rs index 07d8905f8..27ffbfeea 100644 --- a/crates/pecos-quantum/src/unitary_matrix.rs +++ b/crates/pecos-quantum/src/unitary_matrix.rs @@ -1951,7 +1951,7 @@ fn gate_to_matrix(gate_type: GateType, qubits: &[usize], num_qubits: usize) -> D | GateType::MeasCrosstalkLocalPayload | GateType::Channel | GateType::Custom - | GateType::PauliOperatorMeta => { + | GateType::TrackedPauliMeta => { panic!("GateType::{gate_type:?} cannot be converted to a unitary matrix") } } diff --git a/crates/pecos-simulators/src/bitmask_pauli_prop.rs b/crates/pecos-simulators/src/bitmask_pauli_prop.rs index 539cd845d..2fead22f4 100644 --- a/crates/pecos-simulators/src/bitmask_pauli_prop.rs +++ b/crates/pecos-simulators/src/bitmask_pauli_prop.rs @@ -14,7 +14,7 @@ //! //! This type tracks only the binary X/Z support of a propagating Pauli. It //! intentionally ignores global phase, matching the fault-catalog use case -//! where only measurement flips and anticommutation with tracked operators +//! where only measurement flips and anticommutation with tracked Paulis //! matter. use crate::clifford_gateable::{CliffordGateable, MeasurementResult}; diff --git a/crates/pecos-simulators/src/quantum_simulator.rs b/crates/pecos-simulators/src/quantum_simulator.rs index 4b747d0bb..740b45116 100644 --- a/crates/pecos-simulators/src/quantum_simulator.rs +++ b/crates/pecos-simulators/src/quantum_simulator.rs @@ -19,7 +19,7 @@ pub trait QuantumSimulator { /// /// The exact meaning of reset depends on the simulator type: /// - For state vector simulators: resets to |0⟩ state - /// - For observable propagators: clears tracked operators + /// - For observable propagators: clears tracked Paulis /// - For stabilizer simulators: resets to trivial stabilizer group /// /// # Returns diff --git a/docs/README.md b/docs/README.md index c6abac082..9eab704d6 100644 --- a/docs/README.md +++ b/docs/README.md @@ -115,7 +115,7 @@ PECOS is available in multiple languages: This documentation is organized to help you get the most out of PECOS: - **[User Guide](user-guide/getting-started.md)**: Tutorials and guides for using PECOS -- **[PECOS Concepts](user-guide/pecos-concepts.md)**: Core terminology for detectors, observables, tracked operators, gates, and noise +- **[PECOS Concepts](user-guide/pecos-concepts.md)**: Core terminology for detectors, observables, tracked Paulis, gates, and noise - **[Concepts](concepts/index.md)**: Physics, math, and algorithms behind the simulators - **API Reference**: Detailed API documentation - [Python API](https://quantum-pecos.readthedocs.io/en/latest/) diff --git a/docs/user-guide/fault-catalog.md b/docs/user-guide/fault-catalog.md index acae9458d..f5a7e2f18 100644 --- a/docs/user-guide/fault-catalog.md +++ b/docs/user-guide/fault-catalog.md @@ -57,7 +57,7 @@ JSON strings by hand. single-qubit depolarizing channel, 15 alternatives for two-qubit). - When the location fires, exactly one alternative is chosen uniformly. - Each alternative records which measurements, detectors, observables, and - tracked operators it flips. + tracked Paulis it flips. - Multi-fault effects combine by XOR parity. ## Structural vs Parameterized Catalogs @@ -187,13 +187,13 @@ Each `FaultAlternative` is one possible outcome when its parent location fires. | `measurements` | Raw measurement indices flipped | | `detectors` | Detector indices flipped | | `observables` | Observable indices flipped | -| `tracked_ops` | Tracked operator indices flipped | +| `tracked_paulis` | Tracked Pauli indices flipped | | `conditional_probability` | `1 / k_i` (structural, does not depend on noise) | | `absolute_probability` | `p_i / k_i` (0 if unparameterized) | | `channel_probability` | Same `p_i` as the parent location | The four effect fields (`measurements`, `detectors`, `observables`, -`tracked_ops`) are structural -- they depend on the circuit topology, not the +`tracked_paulis`) are structural -- they depend on the circuit topology, not the noise model. They are populated during construction and never change when noise is re-parameterized. @@ -206,7 +206,7 @@ for loc in catalog: print(f" measurements: {fault.measurements}") print(f" detectors: {fault.detectors}") print(f" observables: {fault.observables}") - print(f" tracked_ops: {fault.tracked_ops}") + print(f" tracked_paulis: {fault.tracked_paulis}") ``` `fault.absolute_probability` is local to one fault location. It is not the @@ -437,7 +437,7 @@ for loc in &catalog.locations { fault.kind, fault.affected_detectors, fault.affected_observables, - fault.affected_tracked_ops, + fault.affected_tracked_paulis, fault.absolute_probability ); } @@ -492,13 +492,13 @@ D0 flipped by None at MZ([0]) ## Tracked Operators -Tracked operators are Pauli operators that the catalog monitors for +Tracked Paulis are Pauli strings that the catalog monitors for anticommutation with fault events. Unlike observables, they have no measurement records -- they are detected by forward Pauli propagation. See [PECOS Concepts](pecos-concepts.md) for the full detector, observable, -and tracked-operator distinction. +and tracked-Pauli distinction. -Add tracked operators to a circuit via `tracked_operator`: +Add tracked Paulis to a circuit via `tracked_pauli`: ```python @@ -508,21 +508,21 @@ tc2.set_meta("num_measurements", "0") tc2.set_meta("detectors", "[]") tc2.set_meta("observables", "[]") # Track Z on qubit 0 -- X and Y faults after H anticommute with Z -tc2.tracked_operator(Z(0), label="track_Z0") +tc2.tracked_pauli(Z(0), label="track_Z0") cat2 = fault_catalog(tc2, p1=0.01, p2=0.0, p_meas=0.0, p_prep=0.0) for loc in cat2: for alt in loc.faults: - if alt.tracked_ops: - print(f"{alt.pauli} flips tracked ops {alt.tracked_ops}") + if alt.tracked_paulis: + print(f"{alt.pauli} flips tracked Paulis {alt.tracked_paulis}") ``` ```output -X_0 flips tracked ops [0] -Y_0 flips tracked ops [0] +X_0 flips tracked Paulis [0] +Y_0 flips tracked Paulis [0] ``` No measurement is needed -- the catalog detects that X and Y faults after H -anticommute with the tracked Z operator. This is useful for studying logical +anticommute with the tracked Z Pauli. This is useful for studying logical operator propagation independently of measurement outcomes. ## Raw Measurement Sampling diff --git a/docs/user-guide/getting-started.md b/docs/user-guide/getting-started.md index 11d6264cb..8fbeb2b16 100644 --- a/docs/user-guide/getting-started.md +++ b/docs/user-guide/getting-started.md @@ -167,7 +167,7 @@ The Python example uses a state vector simulator, which supports all quantum gat ## Next Steps - **[HUGR & Guppy Simulation](hugr-simulation.md)**: Measurement-based control flow and advanced Guppy features -- **[PECOS Concepts](pecos-concepts.md)**: Detectors, observables, tracked operators, gates, channels, and fault locations +- **[PECOS Concepts](pecos-concepts.md)**: Detectors, observables, tracked Paulis, gates, channels, and fault locations - **[QASM Simulation](qasm-simulation.md)**: Full QASM simulation API for existing OpenQASM code - **[Simulators](simulators.md)**: Choose the right simulation backend - **[Noise Model Builders](noise-model-builders.md)**: Add realistic noise to your simulations diff --git a/docs/user-guide/pecos-concepts.md b/docs/user-guide/pecos-concepts.md index 0db073949..607d9aa97 100644 --- a/docs/user-guide/pecos-concepts.md +++ b/docs/user-guide/pecos-concepts.md @@ -10,7 +10,7 @@ the public API should make the distinction clear. |---|---|---|---| | Detector | A parity check on measurement records | Measurement record metadata | Syndrome bit | | Observable | A measured logical or experiment output | Measurement record metadata | Logical class decoded from the syndrome | -| Tracked operator | A Pauli operator inserted as a non-physical probe | Circuit annotation | Analysis output, ignored by ordinary DEM decoders | +| Tracked Pauli | A Pauli operator inserted as a non-physical probe | Circuit annotation | Analysis output, ignored by ordinary DEM decoders | | Gate | An ideal operation in a circuit | Circuit builder | No noise unless a noise model attaches it | | Channel | A physical CPTP map, often noise | Noise model or explicit channel op | Source of stochastic or coherent faults | | Fault location | One independent place a modeled fault can occur | Fault catalog | Unit of fault enumeration and sampling | @@ -28,20 +28,20 @@ measurement records, so they are things the experiment can observe directly or infer from recorded measurement data. Logical error rate terminology in PECOS continues to refer to errors in these logical observables. -**Tracked operators** are Pauli operators placed at a circuit point as probes. +**Tracked Paulis** are Pauli strings placed at a circuit point as probes. They are not measured by that annotation and do not become detector syndrome bits. Fault-analysis code asks whether propagated faults anticommute with the -tracked operator at that point. A tracked operator might be a logical operator, -a stabilizer, or another Pauli probe useful for analysis. +tracked Pauli at that point. A tracked Pauli might be a logical operator, +a stabilizer, or another tracked Pauli useful for analysis. Error events can therefore flip three independent kinds of output: - detectors: what syndrome bits changed - observables: what measured logical or experiment outputs changed -- tracked operators: what Pauli probes anticommute with the propagated fault +- tracked Paulis: which tracked Paulis anticommute with the propagated fault -Do not merge observable IDs and tracked-operator IDs. Observable `0` is always -observable `0`; tracked operators have their own ID space and their own metadata. +Do not merge observable IDs and tracked-Pauli IDs. Observable `0` is always +observable `0`; tracked Paulis have their own ID space and their own metadata. ## Operator Construction @@ -115,7 +115,7 @@ This keeps two actions separate: PECOS detector-error models represent detector and observable effects that ordinary decoders consume. PECOS-specific metadata can also carry tracked -operators for analysis, but tracked operators are not logical observables and +Paulis for analysis, but tracked Paulis are not logical observables and ordinary DEM decoders should ignore them. The fault catalog gives the most detailed per-location view: @@ -123,7 +123,7 @@ The fault catalog gives the most detailed per-location view: - `affected_measurements`: raw measurement flips - `affected_detectors`: syndrome flips - `affected_observables`: measurement-defined logical or experiment outputs -- `affected_tracked_ops`: Pauli probes flipped by anticommutation +- `affected_tracked_paulis`: tracked Paulis flipped by anticommutation ## Recommended Surface-Code Memory Path diff --git a/examples/surface/README.md b/examples/surface/README.md index a0659867f..d7bc1afba 100644 --- a/examples/surface/README.md +++ b/examples/surface/README.md @@ -19,7 +19,7 @@ cargo run -p pecos-qec --example surface_d3_fault_catalog_lookup ``` The expensive loop stays in Rust: for `k = 0..=2`, the example lazily walks -`catalog.fault_configurations(k)`, XORs detector/tracked-op effects via the +`catalog.fault_configurations(k)`, XORs detector/tracked-Pauli effects via the catalog iterator, and sums `configuration_probability` into a `syndrome -> logical -> probability` table. diff --git a/examples/surface_code_noisy_decoding.ipynb b/examples/surface_code_noisy_decoding.ipynb index 96404c39c..330d661d7 100644 --- a/examples/surface_code_noisy_decoding.ipynb +++ b/examples/surface_code_noisy_decoding.ipynb @@ -1115,7 +1115,7 @@ "builder.with_measurement_order(measurement_order)\n", "builder.with_detectors_json(detectors_json)\n", "if observables_json:\n", - " builder.with_tracked_ops_json(observables_json)\n", + " builder.with_tracked_paulis_json(observables_json)\n", "\n", "pecos_dem = builder.build()\n", "\n", diff --git a/examples/surface_code_selene_demo.ipynb b/examples/surface_code_selene_demo.ipynb index bc8742626..3844f7882 100644 --- a/examples/surface_code_selene_demo.ipynb +++ b/examples/surface_code_selene_demo.ipynb @@ -668,7 +668,7 @@ "PECOS provides native DEM generation that works directly with TickCircuit,\n", "without requiring Stim as an intermediate step. The workflow is:\n", "\n", - "1. `SurfacePatch` -> `TickCircuit` (with detector/tracked-op metadata)\n", + "1. `SurfacePatch` -> `TickCircuit` (with detector/tracked-Pauli metadata)\n", "2. `TickCircuit` -> `DagCircuit` -> `DagFaultAnalyzer` -> `DemBuilder`\n", "3. `DemBuilder` -> DEM string (Stim-compatible format)\n", "\n", @@ -736,7 +736,7 @@ " builder.with_measurement_order(measurement_order)\n", " builder.with_detectors_json(detectors_json)\n", " if observables_json:\n", - " builder.with_tracked_ops_json(observables_json)\n", + " builder.with_tracked_paulis_json(observables_json)\n", "\n", " return builder.build()" ] diff --git a/examples/surface_code_slr_exploration.ipynb b/examples/surface_code_slr_exploration.ipynb index 9f286c86c..4af7f0ec4 100644 --- a/examples/surface_code_slr_exploration.ipynb +++ b/examples/surface_code_slr_exploration.ipynb @@ -630,7 +630,7 @@ "\n", "4. **Key gaps for parity with circuit builder:**\n", " - No TickCircuit generator\n", - " - No detector/tracked-op annotation support\n", + " - No detector/tracked-Pauli annotation support\n", " - No semantic phase metadata\n", " - No gate-level metadata (labels, stabilizer info)\n", " - No CNOT scheduling in SLR's surface library\n", diff --git a/examples/surface_code_threshold.ipynb b/examples/surface_code_threshold.ipynb index ab5977207..90e15a997 100644 --- a/examples/surface_code_threshold.ipynb +++ b/examples/surface_code_threshold.ipynb @@ -169,7 +169,7 @@ " builder.with_measurement_order(measurement_order)\n", " builder.with_detectors_json(detectors_json)\n", " if observables_json:\n", - " builder.with_tracked_ops_json(observables_json)\n", + " builder.with_tracked_paulis_json(observables_json)\n", "\n", " dem = builder.build()\n", " return dem.to_string(), dem.to_string_decomposed()\n", diff --git a/exp/pecos-eeg/src/builder.rs b/exp/pecos-eeg/src/builder.rs index 96cc5c5d5..4eaa9cad6 100644 --- a/exp/pecos-eeg/src/builder.rs +++ b/exp/pecos-eeg/src/builder.rs @@ -213,7 +213,7 @@ fn build_detectors( pauli: bitmask, }); } - AnnotationKind::TrackedOperator => {} + AnnotationKind::TrackedPauli => {} } } diff --git a/exp/pecos-experimental/src/hugr_executor.rs b/exp/pecos-experimental/src/hugr_executor.rs index 9bdfa411b..c514664df 100644 --- a/exp/pecos-experimental/src/hugr_executor.rs +++ b/exp/pecos-experimental/src/hugr_executor.rs @@ -214,7 +214,7 @@ where | GateType::Idle | GateType::MeasCrosstalkGlobalPayload | GateType::MeasCrosstalkLocalPayload - | GateType::PauliOperatorMeta => {} + | GateType::TrackedPauliMeta => {} // Single-qubit Clifford gates GateType::X => { diff --git a/exp/pecos-stab-tn/src/stab_mps.rs b/exp/pecos-stab-tn/src/stab_mps.rs index c6a082852..4a115d751 100644 --- a/exp/pecos-stab-tn/src/stab_mps.rs +++ b/exp/pecos-stab-tn/src/stab_mps.rs @@ -5899,39 +5899,28 @@ mod tests { } #[test] - fn test_pauli_frame_faster_than_eager_for_many_noise_injects() { - // Timing sanity check: many Pauli injections into frame should - // be far faster than applying each to tableau. - use std::time::Instant; - let n = 32; - let num_injects = 10_000; + fn test_pauli_frame_matches_eager_for_many_noise_injects() { + let n = 6; + let num_injects = 1_000; let mut stn_frame = StabMps::builder(n) .seed(1) .pauli_frame_tracking(true) .build(); - let start = Instant::now(); - for _ in 0..num_injects { - stn_frame.apply_depolarizing(QubitId(0), 1.0); - } - let t_frame = start.elapsed().as_secs_f64(); - let mut stn_eager = StabMps::builder(n).seed(1).build(); - let start = Instant::now(); - for _ in 0..num_injects { - stn_eager.apply_depolarizing(QubitId(0), 1.0); + + for k in 0..num_injects { + let q = QubitId(k % n); + let frame_pauli = stn_frame.apply_depolarizing(q, 1.0); + let eager_pauli = stn_eager.apply_depolarizing(q, 1.0); + assert_eq!(frame_pauli, eager_pauli); } - let t_eager = start.elapsed().as_secs_f64(); - // Frame tracking should be at least 2x faster. - eprintln!( - "Pauli frame: {t_frame:.4}s; eager: {t_eager:.4}s → {:.1}x", - t_eager / t_frame - ); - assert!( - t_frame * 2.0 < t_eager, - "frame tracking should be >2x faster: frame={t_frame:.4}s eager={t_eager:.4}s" - ); + stn_frame.flush_pauli_frame_to_state(); + let frame_sv = stn_frame.state_vector(); + let eager_sv = stn_eager.state_vector(); + + assert_state_vectors_match(&frame_sv, &eager_sv, "frame vs eager Pauli injections"); } #[test] diff --git a/python/pecos-rslib-cuda/src/lib.rs b/python/pecos-rslib-cuda/src/lib.rs index 1f3b61047..e68c01c60 100644 --- a/python/pecos-rslib-cuda/src/lib.rs +++ b/python/pecos-rslib-cuda/src/lib.rs @@ -19,7 +19,9 @@ use pecos_core::{Angle64, QubitId}; use pecos_cuquantum::{ ArbitraryRotationGateable, CliffordGateable, CuDensityMat, CuStabilizer, CuStateVec, - CuTensorNet, QuantumSimulator, is_cuquantum_available as cuquantum_available, + CuTensorNet, QuantumSimulator, is_cudensitymat_usable as cudensitymat_usable, + is_cuquantum_available as cuquantum_available, is_custabilizer_usable as custabilizer_usable, + is_custatevec_usable as custatevec_usable, is_cutensornet_usable as cutensornet_usable, }; use pyo3::exceptions::PyRuntimeError; use pyo3::prelude::*; @@ -32,6 +34,30 @@ fn is_cuquantum_available() -> bool { cuquantum_available() } +/// Check if the cuStateVec backend can create a simulator on this system. +#[pyfunction] +fn is_custatevec_usable() -> bool { + custatevec_usable() +} + +/// Check if the cuStabilizer backend can create a frame simulator on this system. +#[pyfunction] +fn is_custabilizer_usable() -> bool { + custabilizer_usable() +} + +/// Check if the cuTensorNet backend can create a handle on this system. +#[pyfunction] +fn is_cutensornet_usable() -> bool { + cutensornet_usable() +} + +/// Check if the cuDensityMat backend can create a simulator on this system. +#[pyfunction] +fn is_cudensitymat_usable() -> bool { + cudensitymat_usable() +} + /// GPU-accelerated state vector quantum simulator using cuQuantum. /// /// This simulator can handle up to approximately 30 qubits (limited by GPU memory). @@ -851,8 +877,12 @@ impl PyCuDensityMat { fn pecos_rslib_cuda(_py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> { log::debug!("pecos_rslib_cuda module initializing..."); - // Add availability check function + // Add availability check functions m.add_function(wrap_pyfunction!(is_cuquantum_available, m)?)?; + m.add_function(wrap_pyfunction!(is_custatevec_usable, m)?)?; + m.add_function(wrap_pyfunction!(is_custabilizer_usable, m)?)?; + m.add_function(wrap_pyfunction!(is_cutensornet_usable, m)?)?; + m.add_function(wrap_pyfunction!(is_cudensitymat_usable, m)?)?; // Add simulator classes m.add_class::()?; diff --git a/python/pecos-rslib-exp/src/sim_neo_bindings.rs b/python/pecos-rslib-exp/src/sim_neo_bindings.rs index 96522500b..57fd31c7f 100644 --- a/python/pecos-rslib-exp/src/sim_neo_bindings.rs +++ b/python/pecos-rslib-exp/src/sim_neo_bindings.rs @@ -975,7 +975,7 @@ fn build_rust_tick_circuit_from_gates( create_annotations_from_json(&mut tc, &s, &all_meas_refs, false); tc.set_meta("observables", Attribute::String(s)); } - copy_tracked_operator_annotations_from_python(py_tc, &mut tc)?; + copy_tracked_pauli_annotations_from_python(py_tc, &mut tc)?; // Compact for performance tc.compact_ticks(); @@ -983,7 +983,7 @@ fn build_rust_tick_circuit_from_gates( Ok(tc) } -fn copy_tracked_operator_annotations_from_python( +fn copy_tracked_pauli_annotations_from_python( py_tc: &pyo3::Bound<'_, pyo3::PyAny>, tc: &mut pecos_quantum::TickCircuit, ) -> PyResult<()> { @@ -994,21 +994,21 @@ fn copy_tracked_operator_annotations_from_python( for ann in annotations.try_iter()? { let ann = ann?; let kind: String = ann.get_item("kind")?.extract()?; - if kind != "tracked_operator" { + if kind != "tracked_pauli" { continue; } let pauli_obj = ann.get_item("pauli")?; let pauli_text = pauli_obj.str()?.to_string(); let pauli = parse_python_pauli_string(&pauli_text).ok_or_else(|| { pyo3::exceptions::PyValueError::new_err(format!( - "Could not parse tracked operator annotation: {pauli_text}" + "Could not parse tracked Pauli annotation: {pauli_text}" )) })?; let label: Option = ann.get_item("label")?.extract()?; if let Some(label) = label { - tc.tracked_operator_labeled(&label, pauli); + tc.tracked_pauli_labeled(&label, pauli); } else { - tc.tracked_operator(pauli); + tc.tracked_pauli(pauli); } } @@ -1399,9 +1399,9 @@ pub struct PyFaultAlternative { /// Observable indices flipped #[pyo3(get)] observables: Vec, - /// Tracked-operator indices flipped + /// Tracked-Pauli indices flipped #[pyo3(get)] - tracked_ops: Vec, + tracked_paulis: Vec, /// Probability of this alternative given the mechanism fires (1/k) #[pyo3(get)] conditional_probability: f64, @@ -1468,7 +1468,7 @@ pub struct PyFaultConfiguration { #[pyo3(get)] observables: Vec, #[pyo3(get)] - tracked_ops: Vec, + tracked_paulis: Vec, #[pyo3(get)] selected_probability: f64, #[pyo3(get)] @@ -1517,7 +1517,7 @@ impl PyFaultConfigurationIter { measurements: config.affected_measurements, detectors: config.affected_detectors, observables: config.affected_observables, - tracked_ops: config.affected_tracked_ops, + tracked_paulis: config.affected_tracked_paulis, selected_probability: config.selected_probability, configuration_probability: config.configuration_probability, }) @@ -1620,7 +1620,7 @@ fn py_locations_from_catalog( measurements: fault.affected_measurements.clone(), detectors: fault.affected_detectors.clone(), observables: fault.affected_observables.clone(), - tracked_ops: fault.affected_tracked_ops.clone(), + tracked_paulis: fault.affected_tracked_paulis.clone(), conditional_probability: fault.conditional_probability, absolute_probability: fault.absolute_probability, channel_probability: loc.channel_probability, @@ -1788,7 +1788,7 @@ impl PyFaultCatalog { /// /// Each ``FaultAlternative`` has: ``fault.kind``, ``fault.pauli`` (a real /// PECOS ``PauliString`` or ``None``), ``fault.detectors``, ``fault.observables``, -/// ``fault.tracked_ops``, ``fault.measurements``, ``fault.conditional_probability``, +/// ``fault.tracked_paulis``, ``fault.measurements``, ``fault.conditional_probability``, /// ``fault.absolute_probability``, ``fault.channel_probability``. /// /// When noise is omitted, returns a structural catalog with zero probabilities. diff --git a/python/pecos-rslib/pecos_rslib.pyi b/python/pecos-rslib/pecos_rslib.pyi index 167e43e53..afab181c1 100644 --- a/python/pecos-rslib/pecos_rslib.pyi +++ b/python/pecos-rslib/pecos_rslib.pyi @@ -1441,6 +1441,7 @@ class GateType: Prep: GateType QAlloc: GateType QFree: GateType + TrackedPauliMeta: GateType Custom: GateType @property @@ -1648,7 +1649,7 @@ class TickCircuit: def annotations(self) -> list[Any]: ... def detector(self, measurements: Any, label: str | None = None) -> int: ... def observable(self, measurements: Any, label: str | None = None) -> int: ... - def tracked_operator(self, pauli: PauliString, label: str | None = None) -> int: ... + def tracked_pauli(self, pauli: PauliString, label: str | None = None) -> int: ... def clear(self) -> None: ... def reset(self) -> None: ... def reserve_ticks(self, n: int) -> None: ... diff --git a/python/pecos-rslib/src/dag_circuit_bindings.rs b/python/pecos-rslib/src/dag_circuit_bindings.rs index a55a4970a..31bd12985 100644 --- a/python/pecos-rslib/src/dag_circuit_bindings.rs +++ b/python/pecos-rslib/src/dag_circuit_bindings.rs @@ -605,6 +605,14 @@ impl PyGateType { } } + #[classattr] + #[pyo3(name = "TrackedPauliMeta")] + fn tracked_pauli_meta() -> Self { + Self { + inner: GateType::TrackedPauliMeta, + } + } + #[classattr] #[pyo3(name = "Custom")] fn custom() -> Self { @@ -1455,7 +1463,7 @@ impl PyDagCircuit { }) } - /// Place a tracked-operator annotation at this point in the circuit. + /// Place a tracked-Pauli annotation at this point in the circuit. /// /// Only faults BEFORE this annotation can flip the operator. /// Accepts a `PauliString`, which supports `PauliString.X(0) & PauliString.Z(1)`. @@ -1469,17 +1477,17 @@ impl PyDagCircuit { /// /// Example: /// >>> from pecos import PauliString - /// >>> dag.tracked_operator(PauliString.Z(0) & PauliString.Z(1)) + /// >>> dag.tracked_pauli(PauliString.Z(0) & PauliString.Z(1)) #[pyo3(signature = (pauli, label=None))] - fn tracked_operator( + fn tracked_pauli( &mut self, pauli: &crate::pauli_bindings::PauliString, label: Option, ) -> usize { if let Some(l) = label { - self.inner.tracked_operator_labeled(&l, pauli.inner.clone()) + self.inner.tracked_pauli_labeled(&l, pauli.inner.clone()) } else { - self.inner.tracked_operator(pauli.inner.clone()) + self.inner.tracked_pauli(pauli.inner.clone()) } } @@ -1498,7 +1506,7 @@ impl PyDagCircuit { let kind_str = match &ann.kind { pecos_quantum::AnnotationKind::Detector { .. } => "detector", pecos_quantum::AnnotationKind::Observable { .. } => "observable", - pecos_quantum::AnnotationKind::TrackedOperator => "tracked_operator", + pecos_quantum::AnnotationKind::TrackedPauli => "tracked_pauli", }; dict.set_item("kind", kind_str)?; dict.set_item("label", &ann.label)?; @@ -2828,17 +2836,17 @@ impl PyTickCircuit { Ok(idx) } - /// Place a tracked-operator annotation. + /// Place a tracked-Pauli annotation. #[pyo3(signature = (pauli, label=None))] - fn tracked_operator( + fn tracked_pauli( &mut self, pauli: &crate::pauli_bindings::PauliString, label: Option, ) -> usize { if let Some(l) = label { - self.inner.tracked_operator_labeled(&l, pauli.inner.clone()) + self.inner.tracked_pauli_labeled(&l, pauli.inner.clone()) } else { - self.inner.tracked_operator(pauli.inner.clone()) + self.inner.tracked_pauli(pauli.inner.clone()) } } @@ -2854,7 +2862,7 @@ impl PyTickCircuit { let kind_str = match &ann.kind { pecos_quantum::AnnotationKind::Detector { .. } => "detector", pecos_quantum::AnnotationKind::Observable { .. } => "observable", - pecos_quantum::AnnotationKind::TrackedOperator => "tracked_operator", + pecos_quantum::AnnotationKind::TrackedPauli => "tracked_pauli", }; dict.set_item("kind", kind_str)?; dict.set_item("label", &ann.label)?; diff --git a/python/pecos-rslib/src/fault_tolerance_bindings.rs b/python/pecos-rslib/src/fault_tolerance_bindings.rs index f90ecedda..4d2e459e6 100644 --- a/python/pecos-rslib/src/fault_tolerance_bindings.rs +++ b/python/pecos-rslib/src/fault_tolerance_bindings.rs @@ -213,10 +213,10 @@ impl PyDagFaultInfluenceMap { self.inner.num_observables() } - /// Number of tracked operators. + /// Number of tracked Paulis. #[getter] - fn num_tracked_ops(&self) -> usize { - self.inner.num_tracked_ops() + fn num_tracked_paulis(&self) -> usize { + self.inner.num_tracked_paulis() } /// Get all fault locations. @@ -281,23 +281,23 @@ impl PyDagFaultInfluenceMap { /// Get raw internal non-detector influence indices flipped by a fault. /// /// These are implementation indices used to propagate both observables and - /// tracked operators. Prefer `get_dem_output_indices`, - /// `get_observable_indices`, or `get_tracked_op_indices` for public DEM + /// tracked Paulis. Prefer `get_dem_output_indices`, + /// `get_observable_indices`, or `get_tracked_pauli_indices` for public DEM /// semantics. fn get_internal_dem_output_indices(&self, loc_idx: usize, pauli: u8) -> Vec { self.inner.get_dem_output_indices(loc_idx, pauli).to_vec() } - /// Get tracked-operator indices flipped by a fault. + /// Get tracked-Pauli indices flipped by a fault. /// /// Args: /// `loc_idx`: Location index. /// pauli: Pauli type (1=X, 2=Y, 3=Z). /// /// Returns: - /// List of tracked-operator indices that are flipped by this fault. - fn get_tracked_op_indices(&self, loc_idx: usize, pauli: u8) -> Vec { - self.inner.get_tracked_op_indices(loc_idx, pauli) + /// List of tracked-Pauli indices that are flipped by this fault. + fn get_tracked_pauli_indices(&self, loc_idx: usize, pauli: u8) -> Vec { + self.inner.get_tracked_pauli_indices(loc_idx, pauli) } /// Get observable indices flipped by a fault. @@ -329,16 +329,16 @@ impl PyDagFaultInfluenceMap { self.inner.has_observable_flips(loc_idx, pauli) } - /// Check if a fault at the given location flips any tracked op. + /// Check if a fault at the given location flips any tracked Pauli. /// /// Args: /// `loc_idx`: Location index. /// pauli: Pauli type (1=X, 2=Y, 3=Z). /// /// Returns: - /// True if the fault flips at least one tracked op. - fn has_tracked_op_flips(&self, loc_idx: usize, pauli: u8) -> bool { - self.inner.has_tracked_op_flips(loc_idx, pauli) + /// True if the fault flips at least one tracked Pauli. + fn has_tracked_pauli_flips(&self, loc_idx: usize, pauli: u8) -> bool { + self.inner.has_tracked_pauli_flips(loc_idx, pauli) } /// Get memory statistics for this influence map. @@ -399,7 +399,7 @@ impl PyDagFaultInfluenceMap { dict.set_item("num_dem_outputs", num_dem_outputs)?; dict.set_item("num_internal_dem_outputs", num_internal_dem_outputs)?; dict.set_item("num_observables", self.num_observables())?; - dict.set_item("num_tracked_ops", self.num_tracked_ops())?; + dict.set_item("num_tracked_paulis", self.num_tracked_paulis())?; dict.set_item("detector_offsets_x", det_off_x)?; dict.set_item("detector_data_x", det_data_x)?; dict.set_item("detector_offsets_y", det_off_y)?; @@ -430,10 +430,10 @@ impl PyDagFaultInfluenceMap { fn __repr__(&self) -> String { format!( - "DagFaultInfluenceMap(locations={}, detectors={}, tracked_ops={})", + "DagFaultInfluenceMap(locations={}, detectors={}, tracked_paulis={})", self.num_locations(), self.num_detectors(), - self.num_tracked_ops() + self.num_tracked_paulis() ) } @@ -554,7 +554,7 @@ impl PyDagFaultAnalyzer { /// dag = DagCircuit() /// # ... build circuit ... /// -/// # Build influence map with tracked Pauli operators +/// # Build influence map with tracked Paulis /// builder = InfluenceBuilder(dag) /// builder.with_tracked_z([0, 1, 2]) # Track a Z string on these qubits /// influence_map = builder.build() @@ -564,8 +564,8 @@ pub struct PyInfluenceBuilder { dag: DagCircuit, tracked_x_qubits: Vec, tracked_z_qubits: Vec, - tracked_operators: Vec, - use_circuit_tracked_operators: bool, + tracked_paulis: Vec, + use_circuit_tracked_paulis: bool, } #[pymethods] @@ -580,17 +580,17 @@ impl PyInfluenceBuilder { dag: dag.inner.clone(), tracked_x_qubits: Vec::new(), tracked_z_qubits: Vec::new(), - tracked_operators: Vec::new(), - use_circuit_tracked_operators: false, + tracked_paulis: Vec::new(), + use_circuit_tracked_paulis: false, } } - /// Add an X-string tracked operator. + /// Add an X-string tracked Pauli. /// - /// The operator is X on all specified qubits and is sensitive to Z errors. + /// The tracked Pauli is X on all specified qubits and is sensitive to Z errors. /// /// Args: - /// qubits: List of qubit indices for the tracked X operator. + /// qubits: List of qubit indices for the tracked X Pauli. /// /// Returns: /// Self for method chaining. @@ -599,12 +599,12 @@ impl PyInfluenceBuilder { slf } - /// Add a Z-string tracked operator. + /// Add a Z-string tracked Pauli. /// - /// The operator is Z on all specified qubits and is sensitive to X errors. + /// The tracked Pauli is Z on all specified qubits and is sensitive to X errors. /// /// Args: - /// qubits: List of qubit indices for the tracked Z operator. + /// qubits: List of qubit indices for the tracked Z Pauli. /// /// Returns: /// Self for method chaining. @@ -613,7 +613,7 @@ impl PyInfluenceBuilder { slf } - /// Add a Pauli operator to track. + /// Add a tracked Pauli. /// /// Each entry is a `(qubit, pauli)` tuple where pauli is "X", "Y", or "Z". /// @@ -622,7 +622,7 @@ impl PyInfluenceBuilder { /// /// Returns: /// Self for method chaining. - fn with_tracked_operator( + fn with_tracked_pauli( mut slf: PyRefMut<'_, Self>, entries: Vec<(usize, String)>, ) -> PyResult> { @@ -640,7 +640,7 @@ impl PyInfluenceBuilder { Ok((pauli, pecos_core::QubitId::from(*qubit))) }) .collect::>()?; - slf.tracked_operators + slf.tracked_paulis .push(pecos_core::PauliString::with_phase_and_paulis( pecos_core::QuarterPhase::PlusOne, paulis, @@ -648,16 +648,16 @@ impl PyInfluenceBuilder { Ok(slf) } - /// Use annotations from the circuit (observables and Pauli operators). + /// Use annotations from the circuit (observables and tracked Paulis). /// - /// Extracts observable and `tracked_operator()` annotations from the - /// circuit. Pauli operators are tracked with positional awareness + /// Extracts observable and `tracked_pauli()` annotations from the + /// circuit. Tracked Paulis are propagated with positional awareness /// (only faults before each annotation's position affect it). /// /// Returns: /// Self for method chaining. fn with_circuit_annotations(mut slf: PyRefMut<'_, Self>) -> PyRefMut<'_, Self> { - slf.use_circuit_tracked_operators = true; + slf.use_circuit_tracked_paulis = true; slf } @@ -669,7 +669,7 @@ impl PyInfluenceBuilder { /// 3. Backward propagation to build the influence map /// /// Returns: - /// `DagFaultInfluenceMap` with proper detector definitions and tracked operators. + /// `DagFaultInfluenceMap` with proper detector definitions and tracked Paulis. fn build(&self) -> PyDagFaultInfluenceMap { let mut builder = RustInfluenceBuilder::new(&self.dag); @@ -680,11 +680,11 @@ impl PyInfluenceBuilder { builder = builder.with_z(&self.tracked_z_qubits); } - if self.use_circuit_tracked_operators { + if self.use_circuit_tracked_paulis { builder = builder.with_circuit_annotations(&self.dag); } - for pauli in &self.tracked_operators { - builder = builder.with_tracked_operator(pauli.clone()); + for pauli in &self.tracked_paulis { + builder = builder.with_tracked_pauli(pauli.clone()); } let inner = builder.build(); @@ -693,11 +693,11 @@ impl PyInfluenceBuilder { fn __repr__(&self) -> String { format!( - "InfluenceBuilder(tracked_x={:?}, tracked_z={:?}, tracked_operators={}, circuit_annotations={})", + "InfluenceBuilder(tracked_x={:?}, tracked_z={:?}, tracked_paulis={}, circuit_annotations={})", self.tracked_x_qubits, self.tracked_z_qubits, - self.tracked_operators.len(), - self.use_circuit_tracked_operators, + self.tracked_paulis.len(), + self.use_circuit_tracked_paulis, ) } } @@ -744,18 +744,18 @@ fn split_dem_outputs_for_dem( } let mut observables = Vec::new(); - let mut tracked_ops = Vec::new(); + let mut tracked_paulis = Vec::new(); for &output_id in dem_outputs { if let Some(output) = dem.dem_outputs().get(output_id as usize) { if output.is_observable() { observables.push(output_id); } - if output.is_tracked_operator() { - tracked_ops.push(output_id); + if output.is_tracked_pauli() { + tracked_paulis.push(output_id); } } } - (observables, tracked_ops) + (observables, tracked_paulis) } fn contribution_summary_to_pydict( @@ -766,10 +766,10 @@ fn contribution_summary_to_pydict( let dict = pyo3::types::PyDict::new(py); dict.set_item("detectors", summary.effect.detectors.to_vec())?; let dem_outputs = summary.effect.dem_outputs.to_vec(); - let (observables, tracked_ops) = split_dem_outputs_for_dem(&dem_outputs, dem); + let (observables, tracked_paulis) = split_dem_outputs_for_dem(&dem_outputs, dem); dict.set_item("dem_outputs", &dem_outputs)?; dict.set_item("observables", observables)?; - dict.set_item("tracked_ops", tracked_ops)?; + dict.set_item("tracked_paulis", tracked_paulis)?; dict.set_item("num_contributions", summary.num_contributions)?; dict.set_item("total_probability", summary.total_probability)?; dict.set_item("direct_count", summary.direct_count)?; @@ -791,10 +791,10 @@ fn contribution_render_summary_to_pydict( let dict = pyo3::types::PyDict::new(py); dict.set_item("detectors", summary.effect.detectors.to_vec())?; let dem_outputs = summary.effect.dem_outputs.to_vec(); - let (observables, tracked_ops) = split_dem_outputs_for_dem(&dem_outputs, dem); + let (observables, tracked_paulis) = split_dem_outputs_for_dem(&dem_outputs, dem); dict.set_item("dem_outputs", &dem_outputs)?; dict.set_item("observables", observables)?; - dict.set_item("tracked_ops", tracked_ops)?; + dict.set_item("tracked_paulis", tracked_paulis)?; dict.set_item("rendered_targets", summary.rendered_targets)?; dict.set_item("num_contributions", summary.num_contributions)?; dict.set_item("total_probability", summary.total_probability)?; @@ -869,10 +869,10 @@ fn contribution_record_to_pydict( let dict = pyo3::types::PyDict::new(py); dict.set_item("detectors", contribution.effect.detectors.to_vec())?; let dem_outputs = contribution.effect.dem_outputs.to_vec(); - let (observables, tracked_ops) = split_dem_outputs_for_dem(&dem_outputs, dem); + let (observables, tracked_paulis) = split_dem_outputs_for_dem(&dem_outputs, dem); dict.set_item("dem_outputs", &dem_outputs)?; dict.set_item("observables", observables)?; - dict.set_item("tracked_ops", tracked_ops)?; + dict.set_item("tracked_paulis", tracked_paulis)?; dict.set_item("probability", contribution.probability)?; dict.set_item("location_indices", contribution.location_indices.to_vec())?; dict.set_item( @@ -944,7 +944,7 @@ fn contribution_record_to_pydict( impl PyDetectorErrorModel { /// Build a DetectorErrorModel directly from a circuit and noise. /// - /// Accepts both `TickCircuit` and `DagCircuit`. Reads detector/tracked-op + /// Accepts both `TickCircuit` and `DagCircuit`. Reads detector/tracked-Pauli /// definitions from circuit metadata. /// /// Example: @@ -981,6 +981,21 @@ impl PyDetectorErrorModel { } } + /// Build a DetectorErrorModel from PECOS DEM metadata JSON. + /// + /// This imports observable and tracked-Pauli metadata only; mechanism + /// errors must be provided through DEM text or built from a circuit. + /// + /// Raises: + /// `ValueError`: If the metadata JSON is malformed or uses unsupported fields. + #[staticmethod] + fn from_pecos_metadata_json(json: &str) -> PyResult { + let inner = RustDetectorErrorModel::new() + .with_pecos_metadata_json(json) + .map_err(|err| pyo3::exceptions::PyValueError::new_err(err.to_string()))?; + Ok(Self { inner }) + } + /// Number of detectors in the model. #[getter] fn num_detectors(&self) -> usize { @@ -999,10 +1014,10 @@ impl PyDetectorErrorModel { self.inner.num_dem_outputs() } - /// Number of tracked operators in the model. + /// Number of tracked Paulis in the model. #[getter] - fn num_tracked_ops(&self) -> usize { - self.inner.num_tracked_ops() + fn num_tracked_paulis(&self) -> usize { + self.inner.num_tracked_paulis() } /// Convert the DEM to a string in standard DEM format. @@ -1163,11 +1178,11 @@ impl PyDetectorErrorModel { fn __repr__(&self) -> String { format!( - "DetectorErrorModel(detectors={}, dem_outputs={}, observables={}, tracked_ops={}, contributions={})", + "DetectorErrorModel(detectors={}, dem_outputs={}, observables={}, tracked_paulis={}, contributions={})", self.num_detectors(), self.num_dem_outputs(), self.num_observables(), - self.num_tracked_ops(), + self.num_tracked_paulis(), self.num_contributions() ) } @@ -1296,7 +1311,7 @@ impl PyDemBuilder { /// Set the observable definitions from JSON. /// - /// Tracked operators are carried by the influence map; this helper is for + /// Tracked Paulis are carried by the influence map; this helper is for /// observable metadata. fn with_observables_json(mut slf: PyRefMut<'_, Self>, json: String) -> PyRefMut<'_, Self> { slf.observables_json = Some(json); @@ -3319,10 +3334,10 @@ impl PyDemSampler { self.inner.num_dem_outputs() } - /// Number of tracked operators. + /// Number of tracked Paulis. #[getter] - fn num_tracked_ops(&self) -> usize { - self.inner.num_tracked_ops() + fn num_tracked_paulis(&self) -> usize { + self.inner.num_tracked_paulis() } /// Sample a single shot. @@ -3370,13 +3385,13 @@ impl PyDemSampler { self.inner.sample_batch(num_shots, &mut rng) } - /// Sample direct tracked-operator flips. + /// Sample direct tracked-Pauli flips. /// /// Raises: - /// RuntimeError: If this sampler carries tracked operators but the - /// backend cannot evaluate tracked-operator flips directly. + /// RuntimeError: If this sampler carries tracked Paulis but the + /// backend cannot evaluate tracked-Pauli flips directly. #[pyo3(signature = (seed=None))] - fn sample_tracked_ops(&self, seed: Option) -> PyResult> { + fn sample_tracked_paulis(&self, seed: Option) -> PyResult> { use pecos_random::PecosRng; use rand::RngExt; @@ -3386,17 +3401,17 @@ impl PyDemSampler { }; self.inner - .sample_tracked_operator_flips(&mut rng) + .sample_tracked_pauli_flips(&mut rng) .map_err(|e| PyErr::new::(e.to_string())) } - /// Sample direct tracked-operator flips for multiple shots. + /// Sample direct tracked-Pauli flips for multiple shots. /// /// Raises: - /// RuntimeError: If this sampler carries tracked operators but the - /// backend cannot evaluate tracked-operator flips directly. + /// RuntimeError: If this sampler carries tracked Paulis but the + /// backend cannot evaluate tracked-Pauli flips directly. #[pyo3(signature = (num_shots, seed=None))] - fn sample_tracked_op_batch( + fn sample_tracked_pauli_batch( &self, num_shots: usize, seed: Option, @@ -3410,7 +3425,7 @@ impl PyDemSampler { }; self.inner - .sample_tracked_operator_batch(num_shots, &mut rng) + .sample_tracked_pauli_batch(num_shots, &mut rng) .map_err(|e| PyErr::new::(e.to_string())) } @@ -3471,11 +3486,12 @@ impl PyDemSampler { let actual_seed = seed.unwrap_or_else(|| rand::rng().random()); let stats = self.inner.sample_statistics(num_shots, actual_seed); let observable_indices = self.inner.observable_ids(); - let tracked_op_result = self.inner.tracked_operator_ids(); - let tracked_op_statistics_error = tracked_op_result.as_ref().err().map(ToString::to_string); - let tracked_op_indices = tracked_op_result.unwrap_or_default(); + let tracked_pauli_result = self.inner.tracked_pauli_ids(); + let tracked_pauli_statistics_error = + tracked_pauli_result.as_ref().err().map(ToString::to_string); + let tracked_pauli_indices = tracked_pauli_result.unwrap_or_default(); let per_observable = stats.observable_counts(&observable_indices); - let per_tracked_op: Vec = tracked_op_indices + let per_tracked_pauli: Vec = tracked_pauli_indices .iter() .filter_map(|&idx| stats.dem_output_counts().get(idx).copied()) .collect(); @@ -3483,7 +3499,7 @@ impl PyDemSampler { #[allow(clippy::cast_precision_loss)] // Counts are converted to rates for Python reporting. let n = stats.total_shots as f64; #[allow(clippy::cast_precision_loss)] // Counts are converted to rates for Python reporting. - let tracked_op_rates: Vec = per_tracked_op + let tracked_pauli_rates: Vec = per_tracked_pauli .iter() .map(|&count| count as f64 / n) .collect(); @@ -3498,18 +3514,18 @@ impl PyDemSampler { dict.set_item("undetectable_rate", stats.undetectable_rate())?; dict.set_item("per_detector", &stats.per_detector)?; dict.set_item("per_observable", per_observable)?; - dict.set_item("per_tracked_op", per_tracked_op)?; + dict.set_item("per_tracked_pauli", per_tracked_pauli)?; dict.set_item("per_dem_output", stats.dem_output_counts())?; dict.set_item("detector_rates", stats.detector_rates())?; dict.set_item("logical_rates", logical_rates)?; - dict.set_item("tracked_op_rates", tracked_op_rates)?; + dict.set_item("tracked_pauli_rates", tracked_pauli_rates)?; dict.set_item("dem_output_rates", stats.dem_output_rates())?; dict.set_item( - "tracked_op_statistics_supported", - tracked_op_statistics_error.is_none(), + "tracked_pauli_statistics_supported", + tracked_pauli_statistics_error.is_none(), )?; - if let Some(error) = tracked_op_statistics_error { - dict.set_item("tracked_op_statistics_error", error)?; + if let Some(error) = tracked_pauli_statistics_error { + dict.set_item("tracked_pauli_statistics_error", error)?; } Ok(dict.unbind()) } @@ -3520,7 +3536,7 @@ impl PyDemSampler { /// - `outputs`: labels for output channels (raw measurements or detectors) /// - `dem_outputs`: labels for all DEM `L` targets /// - `observables`: labels for observables - /// - `tracked_ops`: labels for tracked operators + /// - `tracked_paulis`: labels for tracked Paulis /// - `dual_detectors`: labels for dual-output detector channels fn labels(&self, py: Python<'_>) -> PyResult> { let labels = self.inner.labels(); @@ -3528,7 +3544,7 @@ impl PyDemSampler { dict.set_item("outputs", &labels.outputs)?; dict.set_item("dem_outputs", &labels.dem_output_labels)?; dict.set_item("observables", &labels.dem_output_labels)?; - dict.set_item("tracked_ops", &labels.tracked_op_labels)?; + dict.set_item("tracked_paulis", &labels.tracked_pauli_labels)?; dict.set_item("dual_detectors", &labels.dual_detectors)?; Ok(dict.unbind()) } @@ -3662,12 +3678,12 @@ impl PyDemSampler { fn __repr__(&self) -> String { format!( - "DemSampler(mechanisms={}, outputs={}, dem_outputs={}, observables={}, tracked_ops={})", + "DemSampler(mechanisms={}, outputs={}, dem_outputs={}, observables={}, tracked_paulis={})", self.num_mechanisms(), self.num_outputs(), self.num_dem_outputs(), self.num_observables(), - self.num_tracked_ops(), + self.num_tracked_paulis(), ) } } @@ -3736,7 +3752,7 @@ impl PyDemSamplerBuilder { /// Set observable definitions from JSON. /// - /// Tracked operators are carried by the influence map; this helper is for + /// Tracked Paulis are carried by the influence map; this helper is for /// observable metadata. fn with_observables_json(mut slf: PyRefMut<'_, Self>, json: String) -> PyRefMut<'_, Self> { slf.observables_json = Some(json); @@ -3979,10 +3995,10 @@ impl PyParsedDem { self.inner.num_dem_outputs() } - /// Number of tracked operators. + /// Number of tracked Paulis. #[getter] - fn num_tracked_ops(&self) -> u32 { - self.inner.num_tracked_ops() + fn num_tracked_paulis(&self) -> u32 { + self.inner.num_tracked_paulis() } /// Convert to a decomposed (graphlike) DEM string. @@ -4088,12 +4104,12 @@ impl PyParsedDem { fn __repr__(&self) -> String { format!( - "ParsedDem(mechanisms={}, detectors={}, dem_outputs={}, observables={}, tracked_ops={})", + "ParsedDem(mechanisms={}, detectors={}, dem_outputs={}, observables={}, tracked_paulis={})", self.inner.mechanisms.len(), self.inner.num_detectors, self.inner.num_dem_outputs(), self.inner.num_observables(), - self.inner.num_tracked_ops() + self.inner.num_tracked_paulis() ) } } diff --git a/python/pecos-rslib/src/gate_registry_bindings.rs b/python/pecos-rslib/src/gate_registry_bindings.rs index b0d718111..5bb237c93 100644 --- a/python/pecos-rslib/src/gate_registry_bindings.rs +++ b/python/pecos-rslib/src/gate_registry_bindings.rs @@ -59,6 +59,7 @@ fn parse_gate_type(name: &str) -> PyResult { "QAlloc" => Ok(GateType::QAlloc), "QFree" => Ok(GateType::QFree), "Idle" => Ok(GateType::Idle), + "TrackedPauli" | "TrackedPauliMeta" | "TP" => Ok(GateType::TrackedPauliMeta), _ => Err(pyo3::exceptions::PyValueError::new_err(format!( "Unknown gate type: '{name}'" ))), diff --git a/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py b/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py index a533f4b68..14ce63767 100644 --- a/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py +++ b/python/quantum-pecos/src/pecos/qec/surface/circuit_builder.py @@ -887,9 +887,9 @@ def render( current_cx_round = 0 final_meas_start = 0 - # Store all tick metadata to apply at the end (workaround for metadata - # being lost when new ticks are created) - # Format: {tick_idx: {'phase': str, 'round': int, 'cx_round': int, 'gates': [(label, role), ...]}} + # Store tick-level metadata to apply at the end by tick index. Gate + # metadata is attached immediately as each gate is emitted so it + # participates in TickCircuit's batching decisions. all_tick_metadata: dict[int, dict] = {} def get_stabilizer_from_label(label: str) -> str: @@ -982,7 +982,6 @@ def new_tick() -> TickHandle: "phase": current_phase, "round": current_round, "cx_round": current_cx_round, - "gates": [], } return current_tick_handle @@ -1001,24 +1000,34 @@ def mark_qubits_used(qubits: list[int]) -> None: """Mark qubits as used in current tick.""" qubits_in_current_tick.update(qubits) - def queue_gate_metadata(meta: dict | None = None) -> None: - """Queue metadata for the current gate. + def gate_metadata(meta: dict | None = None) -> dict: + """Build metadata for the current gate context. Args: meta: Optional dict with gate metadata (e.g., {"label": "data[0]"}) """ - if current_tick_idx >= 0: - context = { - "phase": current_phase, - } - if current_round >= 0: - context["syndrome_round"] = current_round - if current_cx_round > 0: - context["cx_round"] = current_cx_round - merged_meta = context - if meta: - merged_meta = {**context, **meta} - all_tick_metadata[current_tick_idx]["gates"].append(merged_meta) + context: dict[str, object] = { + "phase": current_phase, + } + if current_round >= 0: + context["syndrome_round"] = current_round + if current_cx_round > 0: + context["cx_round"] = current_cx_round + if meta: + return {**context, **meta} + return context + + def apply_gate_metadata(handle: TickHandle, meta: dict | None = None) -> None: + """Attach metadata to the gate most recently added to a handle.""" + handle.metas(gate_metadata(meta)) + + def apply_measurement_metadata(meas_refs: list, meta: dict | None = None) -> None: + """Attach metadata to the measurement gate just emitted.""" + if not meas_refs: + return + tick_idx, gate_idx, _ = meas_refs[0] + for key, value in gate_metadata(meta).items(): + circuit.set_gate_meta(tick_idx, gate_idx, key, value) for op in ops: if op.op_type == OpType.COMMENT: @@ -1049,58 +1058,58 @@ def queue_gate_metadata(meta: dict | None = None) -> None: tick.qalloc([q]) allocated.add(q) else: - tick.pz([q]) + tick = tick.pz([q]) mark_qubits_used([q]) # Label helps identify which qubit (e.g., "data[0]", "ax0") meta = get_ancilla_gate_metadata(q, op.label) if op.label: meta["label"] = op.label - queue_gate_metadata(meta or None) + apply_gate_metadata(tick, meta or None) elif op.op_type == OpType.PREP: q = op.qubits[0] - get_tick_for_qubits([q]).pz([q]) + tick = get_tick_for_qubits([q]).pz([q]) mark_qubits_used([q]) meta = get_ancilla_gate_metadata(q, op.label) if op.label: meta["label"] = op.label - queue_gate_metadata(meta or None) + apply_gate_metadata(tick, meta or None) elif op.op_type == OpType.H: q = op.qubits[0] - get_tick_for_qubits([q]).h([q]) + tick = get_tick_for_qubits([q]).h([q]) mark_qubits_used([q]) meta = get_ancilla_gate_metadata(q, op.label) if op.label: meta["label"] = op.label - queue_gate_metadata(meta or None) + apply_gate_metadata(tick, meta or None) elif op.op_type == OpType.X: q = op.qubits[0] - get_tick_for_qubits([q]).x([q]) + tick = get_tick_for_qubits([q]).x([q]) mark_qubits_used([q]) meta = get_ancilla_gate_metadata(q, op.label) if op.label: meta["label"] = op.label - queue_gate_metadata(meta or None) + apply_gate_metadata(tick, meta or None) elif op.op_type == OpType.Z: q = op.qubits[0] - get_tick_for_qubits([q]).z([q]) + tick = get_tick_for_qubits([q]).z([q]) mark_qubits_used([q]) meta = get_ancilla_gate_metadata(q, op.label) if op.label: meta["label"] = op.label - queue_gate_metadata(meta or None) + apply_gate_metadata(tick, meta or None) elif op.op_type == OpType.CX: qubits = op.qubits - get_tick_for_qubits(qubits).cx([(qubits[0], qubits[1])]) + tick = get_tick_for_qubits(qubits).cx([(qubits[0], qubits[1])]) mark_qubits_used(qubits) meta = get_cx_gate_metadata(qubits[0], qubits[1], op.label) if op.label: meta["label"] = op.label - queue_gate_metadata(meta or None) + apply_gate_metadata(tick, meta or None) elif op.op_type == OpType.MEASURE: q = op.qubits[0] @@ -1110,7 +1119,7 @@ def queue_gate_metadata(meta: dict | None = None) -> None: meta = get_ancilla_gate_metadata(q, op.label) if op.label: meta["label"] = op.label - queue_gate_metadata(meta or None) + apply_measurement_metadata(meas_refs, meta or None) # Track measurement index and refs for detectors if op.label.startswith("sx"): @@ -1132,9 +1141,8 @@ def queue_gate_metadata(meta: dict | None = None) -> None: current_tick_handle = None qubits_in_current_tick = set() - # Apply tick-level and gate-level metadata - # We use the circuit's set_tick_meta and set_gate_meta methods - # which modify the ticks in place (unlike get_tick() which returns a copy) + # Apply tick-level metadata in place. Gate metadata is attached as each + # gate is emitted so batching decisions can account for it immediately. for tick_idx, tick_meta in all_tick_metadata.items(): # Set tick-level metadata circuit.set_tick_meta(tick_idx, "phase", tick_meta["phase"]) @@ -1143,12 +1151,6 @@ def queue_gate_metadata(meta: dict | None = None) -> None: if tick_meta["cx_round"] > 0: circuit.set_tick_meta(tick_idx, "cx_round", tick_meta["cx_round"]) - # Set gate-level metadata (only for gates that have meaningful metadata) - for gate_idx, gate_meta in enumerate(tick_meta["gates"]): - if gate_meta: - for key, value in gate_meta.items(): - circuit.set_gate_meta(tick_idx, gate_idx, key, value) - # Add detector annotations as metadata if self.add_detectors: geom = patch.geometry @@ -2321,16 +2323,16 @@ def generate_dem_from_tick_circuit_via_autodetection( Args: tc: TickCircuit (detector annotations not required) - tracked_z_qubits: Qubit indices for a tracked Z operator (for X error tracking) - tracked_x_qubits: Qubit indices for a tracked X operator (for Z error tracking) + tracked_z_qubits: Qubit indices for a tracked Z Pauli (for X error tracking) + tracked_x_qubits: Qubit indices for a tracked X Pauli (for Z error tracking) p1: Single-qubit depolarizing error rate p2: Two-qubit depolarizing error rate p_meas: Measurement error rate p_prep: Initialization (prep) error rate Returns: - PECOS DEM string. With no tracked operators this is Stim-compatible; - tracked operators are represented with PECOS `pecos_tracked_op` + PECOS DEM string. With no tracked Paulis this is Stim-compatible; + tracked Paulis are represented with PECOS `pecos_tracked_pauli` metadata lines. """ import json @@ -2411,26 +2413,28 @@ def _pauli_string(pauli: str, qubits: list[int] | None) -> str: return "+I" return "+" + " ".join(f"{pauli}{q}" for q in qubits) - tracked_op_metadata = [] + tracked_pauli_metadata = [] if tracked_x_qubits: - tracked_op_metadata.append( + tracked_pauli_metadata.append( { - "id": len(tracked_op_metadata), - "kind": "tracked_operator", + "id": len(tracked_pauli_metadata), + "kind": "tracked_pauli", "label": "tracked_x", "pauli": _pauli_string("X", tracked_x_qubits), }, ) if tracked_z_qubits: - tracked_op_metadata.append( + tracked_pauli_metadata.append( { - "id": len(tracked_op_metadata), - "kind": "tracked_operator", + "id": len(tracked_pauli_metadata), + "kind": "tracked_pauli", "label": "tracked_z", "pauli": _pauli_string("Z", tracked_z_qubits), }, ) - lines.extend(f"pecos_tracked_op {json.dumps(metadata, separators=(',', ':'))}" for metadata in tracked_op_metadata) + lines.extend( + f"pecos_tracked_pauli {json.dumps(metadata, separators=(',', ':'))}" for metadata in tracked_pauli_metadata + ) # Add error mechanisms for (dets, dem_outputs), prob in sorted( diff --git a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock index dcd1e1d96..54c0f47d5 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock +++ b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock @@ -610,27 +610,27 @@ dependencies = [ [[package]] name = "cranelift-assembler-x64" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "046d4b584c3bb9b5eb500c8f29549bec36be11000f1ba2a927cef3d1a9875691" +checksum = "adc822414b18d1f5b1b33ce1441534e311e62fef86ebb5b9d382af857d0272c9" dependencies = [ "cranelift-assembler-x64-meta", ] [[package]] name = "cranelift-assembler-x64-meta" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b9b194a7870becb1490366fc0ae392ccd188065ff35f8391e77ac659db6fb977" +checksum = "8c646808b06f4532478d8d6057d74f15c3322f10d995d9486e7dcea405bf521a" dependencies = [ "cranelift-srcgen", ] [[package]] name = "cranelift-bforest" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "bb6a4ab44c6b371e661846b97dab687387a60ac4e2f864e2d4257284aad9e889" +checksum = "7b5996f01a686b2349cdb379083ec5ad3e8cb8767fb2d495d3a4f2ee4163a18d" dependencies = [ "cranelift-entity", "wasmtime-internal-core", @@ -638,9 +638,9 @@ dependencies = [ [[package]] name = "cranelift-bitset" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b8b7a44150c2f471a94023482bda1902710746e4bed9f9973d60c5a94319b06d" +checksum = "523fea83273f6a985520f57788809a4de2165794d9ab00fb1254fceb4f5aa00c" dependencies = [ "serde", "serde_derive", @@ -649,9 +649,9 @@ dependencies = [ [[package]] name = "cranelift-codegen" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "01b06598133b1dd76758b8b95f8d6747c124124aade50cea96a3d88b962da9fa" +checksum = "d73d1e372730b5f64ed1a2bd9f01fe4686c8ec14a28034e3084e530c8d951878" dependencies = [ "bumpalo", "cranelift-assembler-x64", @@ -677,9 +677,9 @@ dependencies = [ [[package]] name = "cranelift-codegen-meta" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "6190e2e7bcf0a678da2f715363d34ed530fedf7a2f0ab75edaefef72a70465ff" +checksum = "b0319c18165e93dc1ebf78946a8da0b1c341c95b4a39729a69574671639bdb5f" dependencies = [ "cranelift-assembler-x64-meta", "cranelift-codegen-shared", @@ -690,24 +690,24 @@ dependencies = [ [[package]] name = "cranelift-codegen-shared" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "f583cf203d1aa8b79560e3b01f929bdacf9070b015eec4ea9c46e22a3f83e4a0" +checksum = "9195cd8aeecb55e401aa96b2eaa55921636e8246c127ed7908f7ef7e0d40f270" [[package]] name = "cranelift-control" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "803159df35cc398ae54473c150b16d6c77e92ab2948be638488de126a3328fbc" +checksum = "8976c2154b74136322befc74222ab5c7249edd7e2604f8cbef2b94975541ffb9" dependencies = [ "arbitrary", ] [[package]] name = "cranelift-entity" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "3109e417257082d88087f5bcce677525bdaa8322b88dd7f175ed1a1fd41d546c" +checksum = "6038b3147c7982f4951150d5f96c7c06c1e7214b99d4b4a98607aadf8ded89d1" dependencies = [ "cranelift-bitset", "serde", @@ -717,9 +717,9 @@ dependencies = [ [[package]] name = "cranelift-frontend" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "14db6b0e0e4994c581092df78d837be2072578f7cb2528f96a6cf895e56dee63" +checksum = "4cbd294abe236e23cc3d907b0936226b6a8342db7636daa9c7c72be1e323420e" dependencies = [ "cranelift-codegen", "log", @@ -729,15 +729,15 @@ dependencies = [ [[package]] name = "cranelift-isle" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "ec66ea5025c7317383699778282ac98741d68444f956e3b1d7b62f12b7216e67" +checksum = "b5a90b6ed3aba84189352a87badeb93b2126d3724225a42dc67fdce53d1b139c" [[package]] name = "cranelift-native" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "373ade56438e6232619d85678477d0a88a31b3581936e0503e61e96b546b0800" +checksum = "c3ec0cc1a54e22925eacf4fc3dc815f907734d3b377899d19d52bec04863e853" dependencies = [ "cranelift-codegen", "libc", @@ -746,9 +746,9 @@ dependencies = [ [[package]] name = "cranelift-srcgen" -version = "0.130.1" +version = "0.130.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "ef53619d3cd5c78fd998c6d9420547af26b72e6456f94c2a8a2334cb76b42baa" +checksum = "948865622f87f30907bb46fbb081b235ae63c1896a99a83c26a003305c1fa82d" [[package]] name = "crc" @@ -1076,7 +1076,7 @@ dependencies = [ "libc", "option-ext", "redox_users", - "windows-sys 0.59.0", + "windows-sys 0.60.2", ] [[package]] @@ -1203,7 +1203,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb" dependencies = [ "libc", - "windows-sys 0.59.0", + "windows-sys 0.52.0", ] [[package]] @@ -3259,9 +3259,9 @@ dependencies = [ [[package]] name = "pulley-interpreter" -version = "43.0.1" +version = "43.0.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "010dec3755eb61b2f1051ecb3611b718460b7a74c131e474de2af20a845938af" +checksum = "7ec12fe19a9588315a49fe5704502a9c02d6a198303314b0c7c86123b06d29e5" dependencies = [ "cranelift-bitset", "log", @@ -3271,9 +3271,9 @@ dependencies = [ [[package]] name = "pulley-macros" -version = "43.0.1" +version = "43.0.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "ad360c32e85ca4b083ac0e2b6856e8f11c3d5060dafa7d5dc57b370857fa3018" +checksum = "36f7d5ef31ebf1b46cd7e722ffef934e670d7e462f49aa01cde07b9b76dca580" dependencies = [ "proc-macro2", "quote", @@ -3727,7 +3727,7 @@ dependencies = [ "errno", "libc", "linux-raw-sys", - "windows-sys 0.59.0", + "windows-sys 0.52.0", ] [[package]] @@ -3784,7 +3784,7 @@ dependencies = [ "security-framework", "security-framework-sys", "webpki-root-certs", - "windows-sys 0.59.0", + "windows-sys 0.52.0", ] [[package]] @@ -4323,10 +4323,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "32497e9a4c7b38532efcdebeef879707aa9f794296a4f0244f6f69e9bc8574bd" dependencies = [ "fastrand", - "getrandom 0.3.4", + "getrandom 0.4.2", "once_cell", "rustix", - "windows-sys 0.59.0", + "windows-sys 0.52.0", ] [[package]] @@ -4962,9 +4962,9 @@ dependencies = [ [[package]] name = "wasmtime" -version = "43.0.1" +version = "43.0.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "ce205cd643d661b5ba5ba4717e13730262e8cdbc8f2eacbc7b906d45c1a74026" +checksum = "efb1ed5899dde98357cfdcf647a4614498798719793898245b4b34e663addabf" dependencies = [ "addr2line", "async-trait", @@ -5000,9 +5000,9 @@ dependencies = [ [[package]] name = "wasmtime-environ" -version = "43.0.1" +version = "43.0.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "0b8b78abf3677d4a0a5db82e5015b4d085ff3a1b8b472cbb8c70d4b769f019ce" +checksum = "4172382dcc785c31d0e862c6780a18f5dd437914d22c4691351f965ef751c821" dependencies = [ "anyhow", "cranelift-bforest", @@ -5027,9 +5027,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-core" -version = "43.0.1" +version = "43.0.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "22632b187e1b0716f1b9ac57ad29013bed33175fcb19e10bb6896126f82fac67" +checksum = "9a3820b174f477d2a7083209d1ad5353fcdb11eaea434b2137b8681029460dd3" dependencies = [ "hashbrown 0.16.1", "libm", @@ -5038,9 +5038,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-cranelift" -version = "43.0.1" +version = "43.0.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "8b3ca07b3e0bb3429674b173b5800577719d600774dd81bff58f775c0aaa64ee" +checksum = "d1679d205caf9766c6aa309d45bb3e7c634d7725e3164404df33824b9f7c4fb7" dependencies = [ "cfg-if", "cranelift-codegen", @@ -5065,9 +5065,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-fiber" -version = "43.0.1" +version = "43.0.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "20c8b2c9704eb1f33ead025ec16038277ccb63d0a14c31e99d5b765d7c36da55" +checksum = "f1e505254058be5b0df458d670ee42d9eafe2349d04c1296e9dc01071dc20a85" dependencies = [ "cc", "cfg-if", @@ -5080,9 +5080,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-jit-debug" -version = "43.0.1" +version = "43.0.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "d950310d07391d34369f62c48336ebb14eacbd4d6f772bb5f349c24e838e0664" +checksum = "1c2e05b345f1773e59c20e6ad7298fd6857cdea245023d88bb659c96d8f0ea72" dependencies = [ "cc", "wasmtime-internal-versioned-export-macros", @@ -5090,9 +5090,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-jit-icache-coherence" -version = "43.0.1" +version = "43.0.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "3606662c156962d096be3127b8b8ae8ee2f8be3f896dad29259ff01ddb64abfd" +checksum = "b86701b234a4643e3f111869aa792b3a05a06e02d486ee9cb6c04dae16b52dab" dependencies = [ "cfg-if", "libc", @@ -5102,9 +5102,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-unwinder" -version = "43.0.1" +version = "43.0.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "75eef0747e52dc545b075f64fd0e0cc237ae738e641266b1970e07e2d744bc32" +checksum = "f63558d801beb83dde9b336eb4ae049019aee26627926edb32cd119d7e4c83cd" dependencies = [ "cfg-if", "cranelift-codegen", @@ -5115,9 +5115,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-versioned-export-macros" -version = "43.0.1" +version = "43.0.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "d8b0a5dab02a8fb527f547855ecc0e05f9fdc3d5bd57b8b080349408f9a6cece" +checksum = "737c4d956fc3a848541a064afb683dd2771132a6b125be5baaf95c4379aa47df" dependencies = [ "proc-macro2", "quote", @@ -5201,7 +5201,7 @@ version = "0.1.11" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "c2a7b1c03c876122aa43f3020e6c3c3ee5c05081c9a00739faf7503aeba10d22" dependencies = [ - "windows-sys 0.59.0", + "windows-sys 0.52.0", ] [[package]] diff --git a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_catalog.rs b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_catalog.rs index 4864f605b..385fdc037 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_catalog.rs +++ b/python/quantum-pecos/tests/docs/rust_crate/tests/user_guide_fault_catalog.rs @@ -55,7 +55,7 @@ FaultCatalog, StochasticNoiseParams, fault.kind, fault.affected_detectors, fault.affected_observables, - fault.affected_tracked_ops, + fault.affected_tracked_paulis, fault.absolute_probability ); } diff --git a/python/quantum-pecos/tests/pecos/integration/state_sim_tests/test_cuda_simulators.py b/python/quantum-pecos/tests/pecos/integration/state_sim_tests/test_cuda_simulators.py index 3cf7a5c48..e5b118e4f 100644 --- a/python/quantum-pecos/tests/pecos/integration/state_sim_tests/test_cuda_simulators.py +++ b/python/quantum-pecos/tests/pecos/integration/state_sim_tests/test_cuda_simulators.py @@ -23,13 +23,28 @@ import pytest -# Check if CUDA simulators are available +# Check if CUDA simulator libraries and runtime-backed simulators are available. try: - from pecos_rslib_cuda import is_cuquantum_available + from pecos_rslib_cuda import ( + is_cudensitymat_usable, + is_cuquantum_available, + is_custabilizer_usable, + is_custatevec_usable, + is_cutensornet_usable, + ) CUQUANTUM_AVAILABLE = is_cuquantum_available() except ImportError: CUQUANTUM_AVAILABLE = False + CUSTATEVEC_USABLE = False + CUSTABILIZER_USABLE = False + CUTENSORNET_USABLE = False + CUDENSITYMAT_USABLE = False +else: + CUSTATEVEC_USABLE = is_custatevec_usable() + CUSTABILIZER_USABLE = is_custabilizer_usable() + CUTENSORNET_USABLE = is_cutensornet_usable() + CUDENSITYMAT_USABLE = is_cudensitymat_usable() # Skip all tests in this module if cuQuantum is not available pytestmark = pytest.mark.skipif( @@ -41,6 +56,11 @@ class TestCudaStateVec: """Tests for CudaStateVec (Rust cuQuantum state vector simulator).""" + pytestmark = pytest.mark.skipif( + not CUSTATEVEC_USABLE, + reason="CudaStateVec runtime is not usable on this machine", + ) + def test_import(self) -> None: """Test that CudaStateVec can be imported.""" from pecos.simulators import CudaStateVec @@ -172,6 +192,11 @@ def test_run_gate_interface(self) -> None: class TestCudaStabilizer: """Tests for CudaStabilizer (Rust cuQuantum stabilizer simulator).""" + pytestmark = pytest.mark.skipif( + not CUSTABILIZER_USABLE, + reason="CudaStabilizer runtime is not usable on this machine", + ) + def test_import(self) -> None: """Test that CudaStabilizer can be imported.""" from pecos.simulators import CudaStabilizer @@ -275,6 +300,11 @@ def test_surface_code_syndrome(self) -> None: class TestCuTensorNet: """Tests for CuTensorNet handle.""" + pytestmark = pytest.mark.skipif( + not CUTENSORNET_USABLE, + reason="CuTensorNet runtime is not usable on this machine", + ) + def test_import(self) -> None: """Test that CuTensorNet can be imported from pecos_rslib_cuda.""" from pecos_rslib_cuda import CuTensorNet @@ -300,6 +330,11 @@ def test_version(self) -> None: class TestCuDensityMat: """Tests for CuDensityMat density matrix simulator.""" + pytestmark = pytest.mark.skipif( + not CUDENSITYMAT_USABLE, + reason="CuDensityMat runtime is not usable on this machine", + ) + def test_import(self) -> None: """Test that CuDensityMat can be imported from pecos_rslib_cuda.""" from pecos_rslib_cuda import CuDensityMat @@ -337,6 +372,10 @@ def test_small_qubit_count(self) -> None: class TestQuantumSimulatorBackend: """Tests for QuantumSimulator with CUDA backends.""" + @pytest.mark.skipif( + not CUSTATEVEC_USABLE, + reason="CudaStateVec runtime is not usable on this machine", + ) def test_cuda_statevec_backend(self) -> None: """Test QuantumSimulator with CudaStateVec backend.""" from pecos.simulators.quantum_simulator import QuantumSimulator @@ -346,6 +385,10 @@ def test_cuda_statevec_backend(self) -> None: assert sim.num_qubits == 4 + @pytest.mark.skipif( + not CUSTABILIZER_USABLE, + reason="CudaStabilizer runtime is not usable on this machine", + ) def test_cuda_stabilizer_backend(self) -> None: """Test QuantumSimulator with CudaStabilizer backend.""" from pecos.simulators.quantum_simulator import QuantumSimulator diff --git a/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py b/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py index c141c4694..d368f82d9 100644 --- a/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py +++ b/python/quantum-pecos/tests/qec/surface/test_circuit_fuzz.py @@ -6,7 +6,7 @@ Generates random stabilizer circuits, runs them at two levels: 1. Physical: single-qubit PECOS SparseStab (ground truth) 2. Logical: encoded in a surface code via LogicalCircuitBuilder, - TickCircuit replayed on SparseStab with detector/tracked-op checking + TickCircuit replayed on SparseStab with detector/tracked-Pauli checking No Stim dependency. Pure PECOS end-to-end. """ diff --git a/python/quantum-pecos/tests/qec/test_dem_equivalence.py b/python/quantum-pecos/tests/qec/test_dem_equivalence.py index cf653246b..073470eff 100644 --- a/python/quantum-pecos/tests/qec/test_dem_equivalence.py +++ b/python/quantum-pecos/tests/qec/test_dem_equivalence.py @@ -25,10 +25,10 @@ def test_parse_simple_mechanism(self) -> None: assert dem.num_mechanisms == 1 assert dem.num_detectors == 2 assert dem.num_observables == 0 - assert dem.num_tracked_ops == 0 + assert dem.num_tracked_paulis == 0 - def test_parse_mechanism_with_tracked_op(self) -> None: - """Parse mechanism with a Stim DEM output exposed as a tracked op.""" + def test_parse_mechanism_with_tracked_pauli(self) -> None: + """Parse mechanism with a Stim DEM output exposed as a tracked Pauli.""" dem_str = "error(0.02) D0 L0" dem = ParsedDem.from_string(dem_str) @@ -36,7 +36,7 @@ def test_parse_mechanism_with_tracked_op(self) -> None: assert dem.num_detectors == 1 assert dem.num_dem_outputs == 1 assert dem.num_observables == 1 - assert dem.num_tracked_ops == 0 + assert dem.num_tracked_paulis == 0 def test_parse_decomposed_mechanism(self) -> None: """Parse a decomposed mechanism (XOR chain).""" @@ -60,7 +60,7 @@ def test_parse_multiple_mechanisms(self) -> None: assert dem.num_detectors == 3 assert dem.num_dem_outputs == 1 assert dem.num_observables == 1 - assert dem.num_tracked_ops == 0 + assert dem.num_tracked_paulis == 0 def test_parse_detector_declarations(self) -> None: """Parse detector declarations.""" diff --git a/python/quantum-pecos/tests/qec/test_dem_sampler.py b/python/quantum-pecos/tests/qec/test_dem_sampler.py index 0d8b43217..5728e7e4e 100644 --- a/python/quantum-pecos/tests/qec/test_dem_sampler.py +++ b/python/quantum-pecos/tests/qec/test_dem_sampler.py @@ -62,7 +62,7 @@ def test_dem_sampler_sampling() -> None: assert sampler.num_dem_outputs == 1 assert sampler.num_observables == 1 - assert sampler.num_tracked_ops == 0 + assert sampler.num_tracked_paulis == 0 # Single sample det_events, obs_flips = sampler.sample(seed=42) @@ -135,63 +135,93 @@ def test_dem_sampler_statistics() -> None: assert "undetectable_rate" in stats assert "per_dem_output" in stats assert "dem_output_rates" in stats + assert "observable_error_count" not in stats + assert "observable_error_rate" not in stats + assert "per_tracked_op" not in stats + assert "tracked_op_statistics_supported" not in stats assert stats["per_dem_output"] == stats["per_observable"] assert stats["dem_output_rates"] == stats["logical_rates"] - assert stats["tracked_op_statistics_supported"] is True - assert "tracked_op_statistics_error" not in stats - assert sampler.sample_tracked_ops(seed=42) == [] - assert sampler.sample_tracked_op_batch(2, seed=42) == [[], []] + assert stats["tracked_pauli_statistics_supported"] is True + assert "tracked_pauli_statistics_error" not in stats + assert sampler.sample_tracked_paulis(seed=42) == [] + assert sampler.sample_tracked_pauli_batch(2, seed=42) == [[], []] assert stats["total_shots"] == 10000 assert 0.0 <= stats["logical_error_rate"] <= 1.0 assert 0.0 <= stats["syndrome_rate"] <= 1.0 -def test_dem_sampler_tracked_op_labels() -> None: - """Test sampler labels expose PECOS tracked-op terminology.""" +def test_dem_sampler_tracked_pauli_labels() -> None: + """Test sampler labels expose PECOS tracked-Pauli terminology.""" from pecos_rslib import DagCircuit, PauliString from pecos_rslib.qec import DemSampler dag = DagCircuit() dag.pz([0]) dag.h([0]) - dag.tracked_operator(PauliString.from_str("X"), label="x_check") + dag.tracked_pauli(PauliString.from_str("X"), label="x_check") sampler = DemSampler.from_circuit(dag, p1=0.03, p2=0.0, p_meas=0.0, p_prep=0.0) labels = sampler.labels() - assert sampler.num_tracked_ops == 1 + assert sampler.num_tracked_paulis == 1 assert sampler.num_dem_outputs == 0 assert sampler.num_observables == 0 assert "dem_outputs" in labels - assert "tracked_ops" in labels + assert "tracked_paulis" in labels assert labels["dem_outputs"] == [] - assert labels["tracked_ops"] == ["x_check"] + assert labels["tracked_paulis"] == ["x_check"] stats = sampler.sample_statistics(2000, seed=7) assert stats["logical_error_count"] == 0 assert stats["per_observable"] == [] - assert stats["per_tracked_op"] == [] + assert stats["per_tracked_pauli"] == [] assert stats["per_dem_output"] == [] - assert stats["tracked_op_statistics_supported"] is False - assert "cannot directly sample tracked operator flips" in stats["tracked_op_statistics_error"] + assert stats["tracked_pauli_statistics_supported"] is False + assert "cannot directly sample tracked Pauli flips" in stats["tracked_pauli_statistics_error"] - with pytest.raises(RuntimeError, match="cannot directly sample tracked operator flips"): - sampler.sample_tracked_ops(seed=7) - with pytest.raises(RuntimeError, match="cannot directly sample tracked operator flips"): - sampler.sample_tracked_op_batch(4, seed=7) + with pytest.raises(RuntimeError, match="cannot directly sample tracked Pauli flips"): + sampler.sample_tracked_paulis(seed=7) + with pytest.raises(RuntimeError, match="cannot directly sample tracked Pauli flips"): + sampler.sample_tracked_pauli_batch(4, seed=7) -def test_dem_events_split_observables_and_tracked_ops() -> None: - """DEM summaries report detector, observable, and tracked-operator effects separately.""" +def test_detector_error_model_rejects_legacy_tracked_metadata_json() -> None: + """Python metadata import should fail fast on legacy tracked-op fields.""" + from pecos_rslib.qec import DetectorErrorModel + + old_json = """ + { + "format": "pecos.dem.metadata", + "version": 1, + "observables": [], + "tracked_paulis": [], + "tracked_ops": [ + { + "id": 0, + "kind": "tracked_op", + "label": "old_name", + "pauli": "+X0", + "records": [] + } + ] + } + """ + + with pytest.raises(ValueError, match="unsupported legacy metadata field: tracked_ops"): + DetectorErrorModel.from_pecos_metadata_json(old_json) + + +def test_dem_events_split_observables_and_tracked_paulis() -> None: + """DEM summaries report detector, observable, and tracked-Pauli effects separately.""" from pecos_rslib import DagCircuit, PauliString from pecos_rslib.qec import DetectorErrorModel dag = DagCircuit() dag.pz([0]) dag.h([0]) - dag.tracked_operator(PauliString.from_str("X"), label="x_check") + dag.tracked_pauli(PauliString.from_str("X"), label="x_check") dag.mz([0]) dag.set_attr("num_measurements", "1") dag.set_attr("observables", '[{"id": 0, "records": [-1]}]') @@ -207,26 +237,26 @@ def test_dem_events_split_observables_and_tracked_ops() -> None: assert dem.num_dem_outputs == 1 assert dem.num_observables == 1 - assert dem.num_tracked_ops == 1 + assert dem.num_tracked_paulis == 1 assert sampler.num_dem_outputs == 1 assert sampler.num_observables == 1 - assert sampler.num_tracked_ops == 1 - assert sampler.labels()["tracked_ops"] == ["x_check"] + assert sampler.num_tracked_paulis == 1 + assert sampler.labels()["tracked_paulis"] == ["x_check"] summaries = dem.contribution_effect_summaries() assert summaries assert all("dem_outputs" in row for row in summaries) assert all("observables" in row for row in summaries) - assert all("tracked_ops" in row for row in summaries) + assert all("tracked_paulis" in row for row in summaries) observable_hits = {idx for row in summaries for idx in row["observables"]} - tracked_hits = {idx for row in summaries for idx in row["tracked_ops"]} + tracked_hits = {idx for row in summaries for idx in row["tracked_paulis"]} assert 0 in observable_hits assert tracked_hits == set() -def test_sample_decode_count_ignores_tracked_ops() -> None: - """Decoder error counting uses observables, not tracked operators.""" +def test_sample_decode_count_ignores_tracked_paulis() -> None: + """Decoder error counting uses observables, not tracked Paulis.""" from pecos_rslib import DagCircuit, PauliString from pecos_rslib.qec import DemSampler, DetectorErrorModel @@ -234,7 +264,7 @@ def test_sample_decode_count_ignores_tracked_ops() -> None: dag.pz([0]) dag.pz([1]) dag.h([1]) - dag.tracked_operator(PauliString.from_str("IZ"), label="tracked_z") + dag.tracked_pauli(PauliString.from_str("IZ"), label="tracked_z") dag.mz([0]) dag.set_attr("num_measurements", "1") dag.set_attr("detectors", '[{"id": 0, "records": [-1]}]') @@ -257,7 +287,7 @@ def test_sample_decode_count_ignores_tracked_ops() -> None: assert sampler.num_dem_outputs == 1 assert sampler.num_observables == 1 - assert sampler.num_tracked_ops == 1 + assert sampler.num_tracked_paulis == 1 assert "logical_observable L0" in dem.to_string() assert "logical_observable L1" not in dem.to_string() @@ -265,8 +295,8 @@ def test_sample_decode_count_ignores_tracked_ops() -> None: assert errors == 0 -def test_influence_map_tracks_dem_outputs_and_tracked_ops_separately() -> None: - """Test influence maps expose DEM outputs and filtered tracked operators.""" +def test_influence_map_tracks_dem_outputs_and_tracked_paulis_separately() -> None: + """Test influence maps expose DEM outputs and filtered tracked Paulis.""" from pecos_rslib import DagCircuit from pecos_rslib.qec import InfluenceBuilder @@ -275,33 +305,33 @@ def test_influence_map_tracks_dem_outputs_and_tracked_ops_separately() -> None: dag.h([0]) builder = InfluenceBuilder(dag) - builder.with_tracked_operator([(0, "X")]) + builder.with_tracked_pauli([(0, "X")]) influence_map = builder.build() - assert influence_map.num_tracked_ops > 0 + assert influence_map.num_tracked_paulis > 0 assert influence_map.num_observables == 0 assert influence_map.num_dem_outputs == 0 csr = influence_map.export_csr() assert csr["num_dem_outputs"] == influence_map.num_dem_outputs - assert csr["num_internal_dem_outputs"] == influence_map.num_tracked_ops + assert csr["num_internal_dem_outputs"] == influence_map.num_tracked_paulis assert csr["num_observables"] == 0 - assert csr["num_tracked_ops"] == influence_map.num_tracked_ops + assert csr["num_tracked_paulis"] == influence_map.num_tracked_paulis assert "dem_output_offsets_x" in csr assert "dem_output_data_x" in csr for loc_idx in range(influence_map.num_locations): - tracked = influence_map.get_tracked_op_indices(loc_idx, 1) + tracked = influence_map.get_tracked_pauli_indices(loc_idx, 1) dem_outputs = influence_map.get_dem_output_indices(loc_idx, 1) internal_dem_outputs = influence_map.get_internal_dem_output_indices(loc_idx, 1) assert dem_outputs == [] assert tracked == internal_dem_outputs assert not influence_map.has_dem_output_flips(loc_idx, 1) - assert influence_map.has_tracked_op_flips(loc_idx, 1) == bool(tracked) + assert influence_map.has_tracked_pauli_flips(loc_idx, 1) == bool(tracked) -def test_influence_builder_does_not_add_empty_tracked_ops() -> None: - """An unconfigured Python InfluenceBuilder should not create identity tracked ops.""" +def test_influence_builder_does_not_add_empty_tracked_paulis() -> None: + """An unconfigured Python InfluenceBuilder should not create identity tracked Paulis.""" from pecos_rslib import DagCircuit from pecos_rslib.qec import InfluenceBuilder @@ -314,11 +344,11 @@ def test_influence_builder_does_not_add_empty_tracked_ops() -> None: assert influence_map.num_dem_outputs == 0 assert influence_map.num_observables == 0 - assert influence_map.num_tracked_ops == 0 + assert influence_map.num_tracked_paulis == 0 def test_influence_builder_tracked_x_z_are_dem_outputs() -> None: - """Tracked X/Z helpers create tracked operators, not observables.""" + """Tracked X/Z helpers create tracked Paulis, not observables.""" from pecos_rslib import DagCircuit from pecos_rslib.qec import InfluenceBuilder @@ -333,7 +363,7 @@ def test_influence_builder_tracked_x_z_are_dem_outputs() -> None: assert influence_map.num_dem_outputs == 0 assert influence_map.num_observables == 0 - assert influence_map.num_tracked_ops == 2 + assert influence_map.num_tracked_paulis == 2 def test_dem_sampler_zero_noise() -> None: @@ -383,7 +413,7 @@ def test_dem_sampler_repr() -> None: assert "DemSampler" in repr_str assert "mechanisms" in repr_str assert "dem_outputs" in repr_str - assert "tracked_ops" in repr_str + assert "tracked_paulis" in repr_str if __name__ == "__main__": diff --git a/python/quantum-pecos/tests/qec/test_dem_sampler_modes.py b/python/quantum-pecos/tests/qec/test_dem_sampler_modes.py index c0d8eedf1..24a113e61 100644 --- a/python/quantum-pecos/tests/qec/test_dem_sampler_modes.py +++ b/python/quantum-pecos/tests/qec/test_dem_sampler_modes.py @@ -135,7 +135,7 @@ def test_detector_mode_sample_shape(self) -> None: assert len(obs_flips) == 1 assert sampler.num_dem_outputs == 1 assert sampler.num_observables == 1 - assert sampler.num_tracked_ops == 0 + assert sampler.num_tracked_paulis == 0 def test_detector_mode_matches_dem_sampler_builder(self) -> None: """DemSampler detector mode should match DemSamplerBuilder exactly.""" diff --git a/python/quantum-pecos/tests/qec/test_fault_catalog.py b/python/quantum-pecos/tests/qec/test_fault_catalog.py index e33a00533..bd2950276 100644 --- a/python/quantum-pecos/tests/qec/test_fault_catalog.py +++ b/python/quantum-pecos/tests/qec/test_fault_catalog.py @@ -89,7 +89,7 @@ def test_fault_alternative_attributes(self): assert hasattr(fault, "pauli") assert hasattr(fault, "detectors") assert hasattr(fault, "observables") - assert hasattr(fault, "tracked_ops") + assert hasattr(fault, "tracked_paulis") assert hasattr(fault, "measurements") assert hasattr(fault, "conditional_probability") assert hasattr(fault, "absolute_probability") @@ -479,7 +479,7 @@ def test_returns_lazy_iterator_not_list(self): assert hasattr(first, "location_indices") assert hasattr(first, "locations") assert hasattr(first, "faults") - assert hasattr(first, "tracked_ops") + assert hasattr(first, "tracked_paulis") def test_yielded_locations_and_faults(self): tc = build_h_mz() @@ -495,10 +495,10 @@ def test_yielded_locations_and_faults(self): loc = catalog.locations[first.location_indices[0]] assert first.faults[0] is loc.faults[first.alternative_indices[0]] - def test_tracked_ops_are_distinct_from_observables(self): + def test_tracked_paulis_are_distinct_from_observables(self): tc = TickCircuit() tc.tick().h([0]) - tc.tracked_operator(PauliString.from_str("Z"), label="tracked_z") + tc.tracked_pauli(PauliString.from_str("Z"), label="tracked_z") tc.set_meta("detectors", "[]") tc.set_meta("observables", "[]") @@ -506,10 +506,10 @@ def test_tracked_ops_are_distinct_from_observables(self): catalog = fault_catalog(tc, noise) h_loc = next(loc for loc in catalog if loc.gate_type == "H") - tracked = [fault.tracked_ops for fault in h_loc.faults] + tracked = [fault.tracked_paulis for fault in h_loc.faults] assert tracked.count([0]) == 2 assert tracked.count([]) == 1 assert all(fault.observables == [] for fault in h_loc.faults) configs = list(catalog.fault_configurations(1)) - assert any(c.tracked_ops == [0] and c.observables == [] for c in configs) + assert any(c.tracked_paulis == [0] and c.observables == [] for c in configs) diff --git a/python/quantum-pecos/tests/qec/test_parsed_dem_sampler.py b/python/quantum-pecos/tests/qec/test_parsed_dem_sampler.py index f8a0966a8..11537c084 100644 --- a/python/quantum-pecos/tests/qec/test_parsed_dem_sampler.py +++ b/python/quantum-pecos/tests/qec/test_parsed_dem_sampler.py @@ -146,25 +146,32 @@ def test_optimized_sampler_creation(self) -> None: assert sampler.num_mechanisms == 1 assert sampler.num_detectors == 2 - def test_optimized_sampler_projects_tracked_ops_but_fails_direct_sampling(self) -> None: - """Parsed PECOS DEM samplers preserve tracked-op IDs but do not sample them directly.""" + def test_optimized_sampler_projects_tracked_paulis_but_fails_direct_sampling(self) -> None: + """Parsed PECOS DEM samplers preserve tracked-Pauli IDs but do not sample them directly.""" from pecos_rslib.qec import ParsedDem parsed = ParsedDem.from_string("error(0.1) D0 TP1") sampler = parsed.to_dem_sampler() - assert parsed.num_tracked_ops == 2 + assert parsed.num_tracked_paulis == 2 assert sampler.num_detectors == 1 assert sampler.num_dem_outputs == 0 - assert sampler.num_tracked_ops == 2 + assert sampler.num_tracked_paulis == 2 detectors, dem_outputs = sampler.sample(seed=11) assert len(detectors) == 1 assert isinstance(detectors[0], bool) assert dem_outputs == [] - with pytest.raises(RuntimeError, match="cannot directly sample tracked operator flips"): - sampler.sample_tracked_ops(seed=11) + with pytest.raises(RuntimeError, match="cannot directly sample tracked Pauli flips"): + sampler.sample_tracked_paulis(seed=11) + + def test_parser_rejects_legacy_tracked_metadata_extension(self) -> None: + """The PECOS DEM parser should not accept old tracked-op extension lines.""" + from pecos_rslib.qec import ParsedDem + + with pytest.raises(ValueError, match="unsupported PECOS DEM extension line"): + ParsedDem.from_string('pecos_tracked_op {"id":0,"pauli":"+X0"}') def test_optimized_matches_naive_sampler(self) -> None: """Optimized sampler should produce same statistics as naive sampler.""" diff --git a/python/quantum-pecos/tests/qec/test_qec_ux_entrypoints.py b/python/quantum-pecos/tests/qec/test_qec_ux_entrypoints.py index 435603e54..f22efa311 100644 --- a/python/quantum-pecos/tests/qec/test_qec_ux_entrypoints.py +++ b/python/quantum-pecos/tests/qec/test_qec_ux_entrypoints.py @@ -3,6 +3,7 @@ from __future__ import annotations import json +from pathlib import Path import pytest @@ -79,6 +80,38 @@ def test_tick_circuit_metadata_helpers_build_detector_and_observable_json() -> N assert int(tc.get_meta("num_observables")) == 3 +def test_tracked_pauli_public_api_uses_current_names_only() -> None: + from pecos.quantum import DagCircuit, GateRegistry, GateType, TickCircuit, X + + assert GateType.TrackedPauliMeta.name == "TrackedPauli" + assert repr(GateType.TrackedPauliMeta) == "GateType.TrackedPauli" + + stub_text = (Path(__file__).parents[3] / "pecos-rslib" / "pecos_rslib.pyi").read_text() + assert "TrackedPauliMeta: GateType" in stub_text + assert "TrackedOperator" not in stub_text + + for circuit in (DagCircuit(), TickCircuit()): + assert hasattr(circuit, "tracked_pauli") + assert not hasattr(circuit, "tracked_operator") + assert not hasattr(circuit, "tracked_op") + + idx = circuit.tracked_pauli(X(0), label="x_probe") + assert idx == 0 + assert circuit.annotations()[0]["kind"] == "tracked_pauli" + assert circuit.annotations()[0]["label"] == "x_probe" + + for alias in ("TrackedPauli", "TrackedPauliMeta", "TP"): + registry = GateRegistry() + registry.define(f"Use{alias}", 1).step(alias, [0]).register_into(registry) + assert registry.decompose(f"Use{alias}", [7], []) == [ + ("TrackedPauli", [7], [], {}), + ] + + registry = GateRegistry() + with pytest.raises(ValueError, match="Unknown gate type"): + registry.define("Legacy", 1).step("TrackedOperator", [0]) + + def test_tick_circuit_observable_helper_rejects_conflicting_label_id() -> None: from pecos.quantum import TickCircuit @@ -94,7 +127,7 @@ def test_tick_circuit_reset_clears_annotations_and_measurement_records() -> None measurements = tc.tick().mz([0]) tc.detector(measurements) tc.observable(measurements) - tc.tracked_operator(Z(0)) + tc.tracked_pauli(Z(0)) assert tc.num_measurements() == 1 assert len(tc.annotations()) == 3 diff --git a/scripts/docs/generate_doc_tests.py b/scripts/docs/generate_doc_tests.py index 5503db0e2..d716c37af 100755 --- a/scripts/docs/generate_doc_tests.py +++ b/scripts/docs/generate_doc_tests.py @@ -21,7 +21,7 @@ Supported markers in markdown: or - Skip this block - Skip if CUDA+cupy not available - - Skip if CUDA Rust bindings not available + - Skip if CUDA Rust simulators cannot initialize - Expect error matching regex pattern - Expect stdout to contain text - Skip if Python module is unavailable @@ -468,7 +468,7 @@ def generate_test_function(block: CodeBlock, file_stem: str) -> str: ) elif block.skip_if_no_cuda_rust: lines.append( - '@pytest.mark.skipif(not cuda_rust_available(), reason="CUDA Rust bindings not available")', + '@pytest.mark.skipif(not cuda_rust_available(), reason="CUDA Rust simulator runtime not available")', ) lines.extend(f"@pytest.mark.{mark}" for mark in block.marks) @@ -899,10 +899,10 @@ def generate_test_file(file_path: Path, blocks: list[CodeBlock]) -> str: [ "", "def _check_cuda_rust() -> bool:", - ' """Return True if CUDA Rust bindings (pecos_rslib_cuda) are available."""', + ' """Return True if CUDA Rust simulators can initialize."""', " try:", - " from pecos_rslib_cuda import is_cuquantum_available", - " return is_cuquantum_available()", + " from pecos_rslib_cuda import is_custabilizer_usable, is_custatevec_usable", + " return is_custatevec_usable() and is_custabilizer_usable()", " except ImportError:", " return False", "", diff --git a/scripts/native_bench/bench_pecos/Cargo.lock b/scripts/native_bench/bench_pecos/Cargo.lock index 02bd8a052..23fa1c190 100644 --- a/scripts/native_bench/bench_pecos/Cargo.lock +++ b/scripts/native_bench/bench_pecos/Cargo.lock @@ -2081,6 +2081,8 @@ dependencies = [ "num-complex", "pecos-core", "pecos-num", + "pecos-random", + "serde_json", "smallvec", ] @@ -2098,6 +2100,7 @@ dependencies = [ name = "pecos-simulators" version = "0.2.0-dev.0" dependencies = [ + "nalgebra", "num-complex", "pecos-core", "pecos-quantum", @@ -2664,9 +2667,9 @@ checksum = "f87165f0995f63a9fbeea62b64d10b4d9d8e78ec6d7d51fb2125fda7bb36788f" [[package]] name = "rustls-webpki" -version = "0.103.11" +version = "0.103.13" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "20a6af516fea4b20eccceaf166e8aa666ac996208e8a644ce3ef5aa783bc7cd4" +checksum = "61c429a8649f110dddef65e2a5ad240f747e85f7758a6bccc7e5777bd33f756e" dependencies = [ "aws-lc-rs", "ring", From a8dc453856c54f4792d15357b620afd550918c50 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 21:43:43 -0600 Subject: [PATCH 118/125] Upgrade Rust Wasmtime to 44 --- .github/workflows/python-release.yml | 2 + Cargo.lock | 150 ++++++----- Cargo.toml | 2 +- pyproject.toml | 1 - .../tests/docs/rust_crate/Cargo.lock | 243 +++++++++++------- uv.lock | 27 +- 6 files changed, 236 insertions(+), 189 deletions(-) diff --git a/.github/workflows/python-release.yml b/.github/workflows/python-release.yml index 57411c197..305fcfdf3 100644 --- a/.github/workflows/python-release.yml +++ b/.github/workflows/python-release.yml @@ -182,6 +182,7 @@ jobs: # Build configuration CIBW_BUILD: "cp310-*" CIBW_SKIP: "*-win32 *-manylinux_i686 *-musllinux*" + CIBW_BUILD_VERBOSITY: "1" CIBW_ARCHS_LINUX: ${{ matrix.cibw_archs }} CIBW_MANYLINUX_X86_64_IMAGE: "manylinux_2_28" CIBW_MANYLINUX_AARCH64_IMAGE: "manylinux_2_28" @@ -269,6 +270,7 @@ jobs: env: CIBW_BUILD: "cp310-*" CIBW_SKIP: "*-win32 *-manylinux_i686 *-musllinux*" + CIBW_BUILD_VERBOSITY: "1" CIBW_ARCHS_LINUX: ${{ matrix.cibw_archs }} CIBW_MANYLINUX_X86_64_IMAGE: "manylinux_2_28" CIBW_MANYLINUX_AARCH64_IMAGE: "manylinux_2_28" diff --git a/Cargo.lock b/Cargo.lock index d8cd88315..167eb8a3f 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -802,9 +802,9 @@ dependencies = [ [[package]] name = "clap_complete" -version = "4.6.4" +version = "4.6.5" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "e3e962dae2b1e5007fe9e3db363ddc43a8bf25546d279f7a8a4401204690e80c" +checksum = "e0a7a9bfdb35811f9e59832f0f05975114d2251b415fb534108e6f34060fd772" dependencies = [ "clap 4.6.1", ] @@ -932,6 +932,15 @@ dependencies = [ "winapi", ] +[[package]] +name = "cpp_demangle" +version = "0.4.5" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "f2bb79cb74d735044c972aae58ed0aaa9a837e85b01106a54c39e42e97f62253" +dependencies = [ + "cfg-if", +] + [[package]] name = "cpufeatures" version = "0.2.17" @@ -952,27 +961,27 @@ dependencies = [ [[package]] name = "cranelift-assembler-x64" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "adc822414b18d1f5b1b33ce1441534e311e62fef86ebb5b9d382af857d0272c9" +checksum = "f8628cc4ba7f88a9205a7ee42327697abc61195a1e3d92cfae172d6a946e722e" dependencies = [ "cranelift-assembler-x64-meta", ] [[package]] name = "cranelift-assembler-x64-meta" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "8c646808b06f4532478d8d6057d74f15c3322f10d995d9486e7dcea405bf521a" +checksum = "d582754487e6c9a065a91c42ccf1bdd8d5977af33468dac5ae9bec0ce88acb3e" dependencies = [ "cranelift-srcgen", ] [[package]] name = "cranelift-bforest" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "7b5996f01a686b2349cdb379083ec5ad3e8cb8767fb2d495d3a4f2ee4163a18d" +checksum = "fb59c81ace12ee7c33074db7903d4d75d1f40b28cd3e8e6f491de57b29129eb9" dependencies = [ "cranelift-entity", "wasmtime-internal-core", @@ -980,9 +989,9 @@ dependencies = [ [[package]] name = "cranelift-bitset" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "523fea83273f6a985520f57788809a4de2165794d9ab00fb1254fceb4f5aa00c" +checksum = "f25c06993a681be9cf3140798a3d4ac5bec955e7444416a2fdc87fda8567285d" dependencies = [ "serde", "serde_derive", @@ -991,9 +1000,9 @@ dependencies = [ [[package]] name = "cranelift-codegen" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "d73d1e372730b5f64ed1a2bd9f01fe4686c8ec14a28034e3084e530c8d951878" +checksum = "27b61f95c5a211918f5d336254a61a488b36a5818de47a868e8c4658dce9cccc" dependencies = [ "bumpalo", "cranelift-assembler-x64", @@ -1019,9 +1028,9 @@ dependencies = [ [[package]] name = "cranelift-codegen-meta" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b0319c18165e93dc1ebf78946a8da0b1c341c95b4a39729a69574671639bdb5f" +checksum = "0b85aa822fce72080d041d7c2cf7c3f5c6ecdea7afae68379ba4ef85269c4fa5" dependencies = [ "cranelift-assembler-x64-meta", "cranelift-codegen-shared", @@ -1032,24 +1041,24 @@ dependencies = [ [[package]] name = "cranelift-codegen-shared" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "9195cd8aeecb55e401aa96b2eaa55921636e8246c127ed7908f7ef7e0d40f270" +checksum = "833eb9fc89326cd072cc19e96892f09b5692c0dfe17cd4da2858ba30c2cd85c0" [[package]] name = "cranelift-control" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "8976c2154b74136322befc74222ab5c7249edd7e2604f8cbef2b94975541ffb9" +checksum = "9d005320f487e6e8a3edcc7f2fd4f43fcc9946d1013bf206ea649789ac1617fc" dependencies = [ "arbitrary", ] [[package]] name = "cranelift-entity" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "6038b3147c7982f4951150d5f96c7c06c1e7214b99d4b4a98607aadf8ded89d1" +checksum = "5e62ef34c6e720f347a79ece043e8584e242d168911da640bac654a33a6aaaf5" dependencies = [ "cranelift-bitset", "serde", @@ -1059,9 +1068,9 @@ dependencies = [ [[package]] name = "cranelift-frontend" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "4cbd294abe236e23cc3d907b0936226b6a8342db7636daa9c7c72be1e323420e" +checksum = "dfa2ad00399dd47e7e7e33cb1dc23b0e39ed9dcd01e8f026fc37af91655031b8" dependencies = [ "cranelift-codegen", "log", @@ -1071,15 +1080,15 @@ dependencies = [ [[package]] name = "cranelift-isle" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b5a90b6ed3aba84189352a87badeb93b2126d3724225a42dc67fdce53d1b139c" +checksum = "02c51975ed217b4e8e5a7fd11e9ec83a96104bdff311dddcb505d1d8a9fd7fc6" [[package]] name = "cranelift-native" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "c3ec0cc1a54e22925eacf4fc3dc815f907734d3b377899d19d52bec04863e853" +checksum = "f9b1889e00da9729d8f8525f3c12998ded86ea709058ff844ebe00b97548de0e" dependencies = [ "cranelift-codegen", "libc", @@ -1088,9 +1097,9 @@ dependencies = [ [[package]] name = "cranelift-srcgen" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "948865622f87f30907bb46fbb081b235ae63c1896a99a83c26a003305c1fa82d" +checksum = "d5a8f82fd5124f009f72167e60139245cd3b56cfd4b53050f22110c48c5f4da1" [[package]] name = "crc" @@ -2257,6 +2266,9 @@ name = "hashbrown" version = "0.17.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "ed5909b6e89a2db4456e54cd5f673791d7eca6732202bbf2a9cc504fe2f9b84a" +dependencies = [ + "foldhash 0.2.0", +] [[package]] name = "heapz" @@ -3627,12 +3639,12 @@ dependencies = [ [[package]] name = "object" -version = "0.38.1" +version = "0.39.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "271638cd5fa9cca89c4c304675ca658efc4e64a66c716b7cfe1afb4b9611dbbc" +checksum = "2e5a6c098c7a3b6547378093f5cc30bc54fd361ce711e05293a5cc589562739b" dependencies = [ "crc32fast", - "hashbrown 0.16.1", + "hashbrown 0.17.1", "indexmap 2.14.0", "memchr", ] @@ -4966,9 +4978,9 @@ dependencies = [ [[package]] name = "pulley-interpreter" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "7ec12fe19a9588315a49fe5704502a9c02d6a198303314b0c7c86123b06d29e5" +checksum = "b9326e3a0093d170582cf64ed9e4cf253b8aac155ec4a294ff62330450bbf094" dependencies = [ "cranelift-bitset", "log", @@ -4978,9 +4990,9 @@ dependencies = [ [[package]] name = "pulley-macros" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "36f7d5ef31ebf1b46cd7e722ffef934e670d7e462f49aa01cde07b9b76dca580" +checksum = "00c6433917e3789605b1f4cd2a589f637ff17212344e7fa5ba99544625ba52c7" dependencies = [ "proc-macro2", "quote", @@ -5666,6 +5678,12 @@ dependencies = [ "unicode-ident", ] +[[package]] +name = "rustc-demangle" +version = "0.1.27" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "b50b8869d9fc858ce7266cce0194bd74df58b9d0e3f6df3a9fc8eb470d95c09d" + [[package]] name = "rustc-hash" version = "1.1.0" @@ -7174,12 +7192,12 @@ dependencies = [ [[package]] name = "wasm-encoder" -version = "0.245.1" +version = "0.246.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "3f9dca005e69bf015e45577e415b9af8c67e8ee3c0e38b5b0add5aa92581ed5c" +checksum = "61fb705ce81adde29d2a8e99d87995e39a6e927358c91398f374474746070ef7" dependencies = [ "leb128fmt", - "wasmparser 0.245.1", + "wasmparser 0.246.2", ] [[package]] @@ -7218,9 +7236,9 @@ dependencies = [ [[package]] name = "wasmparser" -version = "0.245.1" +version = "0.246.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "4f08c9adee0428b7bddf3890fc27e015ac4b761cc608c822667102b8bfd6995e" +checksum = "71cde4757396defafd25417cfb36aa3161027d06d865b0c24baaae229aac005d" dependencies = [ "bitflags 2.11.1", "hashbrown 0.16.1", @@ -7242,20 +7260,20 @@ dependencies = [ [[package]] name = "wasmprinter" -version = "0.245.1" +version = "0.246.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "5f41517a3716fbb8ccf46daa9c1325f760fcbff5168e75c7392288e410b91ac8" +checksum = "6e41f7493ba994b8a779430a4c25ff550fd5a40d291693af43a6ef48688f00e3" dependencies = [ "anyhow", "termcolor", - "wasmparser 0.245.1", + "wasmparser 0.246.2", ] [[package]] name = "wasmtime" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "efb1ed5899dde98357cfdcf647a4614498798719793898245b4b34e663addabf" +checksum = "372db8bbad8ec962038101f75ab2c3ffcd18797d7d3ae877a58ab9873cd0c4bd" dependencies = [ "addr2line", "async-trait", @@ -7276,7 +7294,7 @@ dependencies = [ "serde_derive", "smallvec", "target-lexicon", - "wasmparser 0.245.1", + "wasmparser 0.246.2", "wasmtime-environ", "wasmtime-internal-core", "wasmtime-internal-cranelift", @@ -7291,11 +7309,12 @@ dependencies = [ [[package]] name = "wasmtime-environ" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "4172382dcc785c31d0e862c6780a18f5dd437914d22c4691351f965ef751c821" +checksum = "1e15aa0d1545e48d9b25ca604e9e27b4cd6d5886d30ac5787b57b3a2daf85b57" dependencies = [ "anyhow", + "cpp_demangle", "cranelift-bforest", "cranelift-bitset", "cranelift-entity", @@ -7305,22 +7324,23 @@ dependencies = [ "log", "object", "postcard", + "rustc-demangle", "serde", "serde_derive", "sha2 0.10.9", "smallvec", "target-lexicon", - "wasm-encoder 0.245.1", - "wasmparser 0.245.1", + "wasm-encoder 0.246.2", + "wasmparser 0.246.2", "wasmprinter", "wasmtime-internal-core", ] [[package]] name = "wasmtime-internal-core" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "9a3820b174f477d2a7083209d1ad5353fcdb11eaea434b2137b8681029460dd3" +checksum = "8f2c7fa6523647262bfb4095dbdf4087accefe525813e783f81a0c682f418ce4" dependencies = [ "hashbrown 0.16.1", "libm", @@ -7329,9 +7349,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-cranelift" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "d1679d205caf9766c6aa309d45bb3e7c634d7725e3164404df33824b9f7c4fb7" +checksum = "98c032f422e39061dfc43f32190c0a3526b04161ec4867f362958f3fe9d1fe29" dependencies = [ "cfg-if", "cranelift-codegen", @@ -7347,7 +7367,7 @@ dependencies = [ "smallvec", "target-lexicon", "thiserror 2.0.18", - "wasmparser 0.245.1", + "wasmparser 0.246.2", "wasmtime-environ", "wasmtime-internal-core", "wasmtime-internal-unwinder", @@ -7356,9 +7376,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-fiber" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "f1e505254058be5b0df458d670ee42d9eafe2349d04c1296e9dc01071dc20a85" +checksum = "d8dd76d80adf450cc260ba58f23c28030401930b19149695b1d121f7d621e791" dependencies = [ "cc", "cfg-if", @@ -7371,9 +7391,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-jit-debug" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "1c2e05b345f1773e59c20e6ad7298fd6857cdea245023d88bb659c96d8f0ea72" +checksum = "ab453cc600b28ee5d3f9495aa6d4cb2c81eda40903e9287296b548fba8b2391d" dependencies = [ "cc", "wasmtime-internal-versioned-export-macros", @@ -7381,9 +7401,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-jit-icache-coherence" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b86701b234a4643e3f111869aa792b3a05a06e02d486ee9cb6c04dae16b52dab" +checksum = "6a1859e920871515d324fb9757c3e448d6ed1512ca6ccdff14b6e016505d6ada" dependencies = [ "cfg-if", "libc", @@ -7393,9 +7413,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-unwinder" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "f63558d801beb83dde9b336eb4ae049019aee26627926edb32cd119d7e4c83cd" +checksum = "f1dfe405bd6adb1386d935a30f16a236bd4ef0d3c383e7cbbab98d063c9d9b73" dependencies = [ "cfg-if", "cranelift-codegen", @@ -7406,9 +7426,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-versioned-export-macros" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "737c4d956fc3a848541a064afb683dd2771132a6b125be5baaf95c4379aa47df" +checksum = "2a9b9165fc45d42c81edfe3e9cb458e58720594ad5db6553c4079ea041a4a581" dependencies = [ "proc-macro2", "quote", diff --git a/Cargo.toml b/Cargo.toml index 0f10afafb..5cdaae24b 100644 --- a/Cargo.toml +++ b/Cargo.toml @@ -70,7 +70,7 @@ tket-qsystem = { version = "0.23", default-features = false } hugr-core = "=0.25.6" # --- WebAssembly --- -wasmtime = { version = "43", default-features = false, features = [ +wasmtime = { version = "44", default-features = false, features = [ "cranelift", "runtime", "wat", diff --git a/pyproject.toml b/pyproject.toml index 890192207..0b973b433 100644 --- a/pyproject.toml +++ b/pyproject.toml @@ -55,7 +55,6 @@ test = [ # exact pins so workspace tests run against a reproducible environment "pytest-timeout==2.4.0", "hypothesis==6.152.1", "stim==1.15.0", # Stim-comparison and decomposition-invariant tests - "wasmtime==43.0.0", # WebAssembly runtime exercised by integration tests "matplotlib>=2.2.0", # Surface-patch render tests import matplotlib directly ] examples = [ # extras used by the examples/ tree and notebook walkthroughs diff --git a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock index 54c0f47d5..9b4910bed 100644 --- a/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock +++ b/python/quantum-pecos/tests/docs/rust_crate/Cargo.lock @@ -590,6 +590,15 @@ version = "0.8.7" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "773648b94d0e5d620f64f280777445740e61fe701025087ec8b57f45c791888b" +[[package]] +name = "cpp_demangle" +version = "0.4.5" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "f2bb79cb74d735044c972aae58ed0aaa9a837e85b01106a54c39e42e97f62253" +dependencies = [ + "cfg-if", +] + [[package]] name = "cpufeatures" version = "0.2.17" @@ -610,27 +619,27 @@ dependencies = [ [[package]] name = "cranelift-assembler-x64" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "adc822414b18d1f5b1b33ce1441534e311e62fef86ebb5b9d382af857d0272c9" +checksum = "f8628cc4ba7f88a9205a7ee42327697abc61195a1e3d92cfae172d6a946e722e" dependencies = [ "cranelift-assembler-x64-meta", ] [[package]] name = "cranelift-assembler-x64-meta" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "8c646808b06f4532478d8d6057d74f15c3322f10d995d9486e7dcea405bf521a" +checksum = "d582754487e6c9a065a91c42ccf1bdd8d5977af33468dac5ae9bec0ce88acb3e" dependencies = [ "cranelift-srcgen", ] [[package]] name = "cranelift-bforest" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "7b5996f01a686b2349cdb379083ec5ad3e8cb8767fb2d495d3a4f2ee4163a18d" +checksum = "fb59c81ace12ee7c33074db7903d4d75d1f40b28cd3e8e6f491de57b29129eb9" dependencies = [ "cranelift-entity", "wasmtime-internal-core", @@ -638,9 +647,9 @@ dependencies = [ [[package]] name = "cranelift-bitset" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "523fea83273f6a985520f57788809a4de2165794d9ab00fb1254fceb4f5aa00c" +checksum = "f25c06993a681be9cf3140798a3d4ac5bec955e7444416a2fdc87fda8567285d" dependencies = [ "serde", "serde_derive", @@ -649,9 +658,9 @@ dependencies = [ [[package]] name = "cranelift-codegen" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "d73d1e372730b5f64ed1a2bd9f01fe4686c8ec14a28034e3084e530c8d951878" +checksum = "27b61f95c5a211918f5d336254a61a488b36a5818de47a868e8c4658dce9cccc" dependencies = [ "bumpalo", "cranelift-assembler-x64", @@ -677,9 +686,9 @@ dependencies = [ [[package]] name = "cranelift-codegen-meta" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b0319c18165e93dc1ebf78946a8da0b1c341c95b4a39729a69574671639bdb5f" +checksum = "0b85aa822fce72080d041d7c2cf7c3f5c6ecdea7afae68379ba4ef85269c4fa5" dependencies = [ "cranelift-assembler-x64-meta", "cranelift-codegen-shared", @@ -690,24 +699,24 @@ dependencies = [ [[package]] name = "cranelift-codegen-shared" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "9195cd8aeecb55e401aa96b2eaa55921636e8246c127ed7908f7ef7e0d40f270" +checksum = "833eb9fc89326cd072cc19e96892f09b5692c0dfe17cd4da2858ba30c2cd85c0" [[package]] name = "cranelift-control" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "8976c2154b74136322befc74222ab5c7249edd7e2604f8cbef2b94975541ffb9" +checksum = "9d005320f487e6e8a3edcc7f2fd4f43fcc9946d1013bf206ea649789ac1617fc" dependencies = [ "arbitrary", ] [[package]] name = "cranelift-entity" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "6038b3147c7982f4951150d5f96c7c06c1e7214b99d4b4a98607aadf8ded89d1" +checksum = "5e62ef34c6e720f347a79ece043e8584e242d168911da640bac654a33a6aaaf5" dependencies = [ "cranelift-bitset", "serde", @@ -717,9 +726,9 @@ dependencies = [ [[package]] name = "cranelift-frontend" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "4cbd294abe236e23cc3d907b0936226b6a8342db7636daa9c7c72be1e323420e" +checksum = "dfa2ad00399dd47e7e7e33cb1dc23b0e39ed9dcd01e8f026fc37af91655031b8" dependencies = [ "cranelift-codegen", "log", @@ -729,15 +738,15 @@ dependencies = [ [[package]] name = "cranelift-isle" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b5a90b6ed3aba84189352a87badeb93b2126d3724225a42dc67fdce53d1b139c" +checksum = "02c51975ed217b4e8e5a7fd11e9ec83a96104bdff311dddcb505d1d8a9fd7fc6" [[package]] name = "cranelift-native" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "c3ec0cc1a54e22925eacf4fc3dc815f907734d3b377899d19d52bec04863e853" +checksum = "f9b1889e00da9729d8f8525f3c12998ded86ea709058ff844ebe00b97548de0e" dependencies = [ "cranelift-codegen", "libc", @@ -746,9 +755,9 @@ dependencies = [ [[package]] name = "cranelift-srcgen" -version = "0.130.2" +version = "0.131.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "948865622f87f30907bb46fbb081b235ae63c1896a99a83c26a003305c1fa82d" +checksum = "d5a8f82fd5124f009f72167e60139245cd3b56cfd4b53050f22110c48c5f4da1" [[package]] name = "crc" @@ -871,7 +880,7 @@ checksum = "b0f4697d190a142477b16aef7da8a99bfdc41e7e8b1687583c0d23a79c7afc1e" dependencies = [ "cc", "codespan-reporting", - "indexmap 2.13.0", + "indexmap 2.14.0", "proc-macro2", "quote", "scratch", @@ -886,7 +895,7 @@ checksum = "d0956799fa8678d4c50eed028f2de1c0552ae183c76e976cf7ca8c4e36a7c328" dependencies = [ "clap", "codespan-reporting", - "indexmap 2.13.0", + "indexmap 2.14.0", "proc-macro2", "quote", "syn", @@ -904,7 +913,7 @@ version = "1.0.194" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "e6acc6b5822b9526adfb4fc377b67128fdd60aac757cc4a741a6278603f763cf" dependencies = [ - "indexmap 2.13.0", + "indexmap 2.14.0", "proc-macro2", "quote", "syn", @@ -1203,7 +1212,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb" dependencies = [ "libc", - "windows-sys 0.52.0", + "windows-sys 0.59.0", ] [[package]] @@ -1436,7 +1445,7 @@ checksum = "0bf7f043f89559805f8c7cacc432749b2fa0d0a0a9ee46ce47164ed5ba7f126c" dependencies = [ "fnv", "hashbrown 0.16.1", - "indexmap 2.13.0", + "indexmap 2.14.0", "stable_deref_trait", ] @@ -1579,6 +1588,15 @@ dependencies = [ "serde_core", ] +[[package]] +name = "hashbrown" +version = "0.17.1" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "ed5909b6e89a2db4456e54cd5f673791d7eca6732202bbf2a9cc504fe2f9b84a" +dependencies = [ + "foldhash 0.2.0", +] + [[package]] name = "heck" version = "0.4.1" @@ -1677,7 +1695,7 @@ dependencies = [ "enum_dispatch", "html-escape", "hugr-model", - "indexmap 2.13.0", + "indexmap 2.14.0", "itertools 0.14.0", "ordered-float", "pastey", @@ -1731,7 +1749,7 @@ dependencies = [ "bumpalo", "capnp", "derive_more 2.1.1", - "indexmap 2.13.0", + "indexmap 2.14.0", "itertools 0.14.0", "ordered-float", "pest", @@ -1983,12 +2001,12 @@ dependencies = [ [[package]] name = "indexmap" -version = "2.13.0" +version = "2.14.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "7714e70437a7dc3ac8eb7e6f8df75fd8eb422675fc7678aff7364301092b1017" +checksum = "d466e9454f08e4a911e14806c24e16fba1b4c121d1ea474396f396069cf949d9" dependencies = [ "equivalent", - "hashbrown 0.16.1", + "hashbrown 0.17.1", "serde", "serde_core", ] @@ -2537,13 +2555,13 @@ dependencies = [ [[package]] name = "object" -version = "0.38.1" +version = "0.39.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "271638cd5fa9cca89c4c304675ca658efc4e64a66c716b7cfe1afb4b9611dbbc" +checksum = "2e5a6c098c7a3b6547378093f5cc30bc54fd361ce711e05293a5cc589562739b" dependencies = [ "crc32fast", - "hashbrown 0.16.1", - "indexmap 2.13.0", + "hashbrown 0.17.1", + "indexmap 2.14.0", "memchr", ] @@ -3088,7 +3106,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "b4c5cc86750666a3ed20bdaf5ca2a0344f9c67674cae0515bec2da16fbaa47db" dependencies = [ "fixedbitset 0.4.2", - "indexmap 2.13.0", + "indexmap 2.14.0", ] [[package]] @@ -3099,7 +3117,7 @@ checksum = "8701b58ea97060d5e5b155d383a69952a60943f0e6dfe30b04c287beb0b27455" dependencies = [ "fixedbitset 0.5.7", "hashbrown 0.15.5", - "indexmap 2.13.0", + "indexmap 2.14.0", "serde", ] @@ -3222,7 +3240,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "93980406f12d9f8140ed5abe7155acb10bb1e69ea55c88960b9c2f117445ef96" dependencies = [ "equivalent", - "indexmap 2.13.0", + "indexmap 2.14.0", "serde", ] @@ -3259,9 +3277,9 @@ dependencies = [ [[package]] name = "pulley-interpreter" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "7ec12fe19a9588315a49fe5704502a9c02d6a198303314b0c7c86123b06d29e5" +checksum = "b9326e3a0093d170582cf64ed9e4cf253b8aac155ec4a294ff62330450bbf094" dependencies = [ "cranelift-bitset", "log", @@ -3271,9 +3289,9 @@ dependencies = [ [[package]] name = "pulley-macros" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "36f7d5ef31ebf1b46cd7e722ffef934e670d7e462f49aa01cde07b9b76dca580" +checksum = "00c6433917e3789605b1f4cd2a589f637ff17212344e7fa5ba99544625ba52c7" dependencies = [ "proc-macro2", "quote", @@ -3702,6 +3720,12 @@ dependencies = [ "unicode-ident", ] +[[package]] +name = "rustc-demangle" +version = "0.1.27" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "b50b8869d9fc858ce7266cce0194bd74df58b9d0e3f6df3a9fc8eb470d95c09d" + [[package]] name = "rustc-hash" version = "2.1.1" @@ -3727,7 +3751,7 @@ dependencies = [ "errno", "libc", "linux-raw-sys", - "windows-sys 0.52.0", + "windows-sys 0.59.0", ] [[package]] @@ -3784,7 +3808,7 @@ dependencies = [ "security-framework", "security-framework-sys", "webpki-root-certs", - "windows-sys 0.52.0", + "windows-sys 0.59.0", ] [[package]] @@ -4060,7 +4084,7 @@ dependencies = [ "chrono", "hex", "indexmap 1.9.3", - "indexmap 2.13.0", + "indexmap 2.14.0", "schemars 0.9.0", "schemars 1.2.1", "serde_core", @@ -4326,7 +4350,7 @@ dependencies = [ "getrandom 0.4.2", "once_cell", "rustix", - "windows-sys 0.52.0", + "windows-sys 0.59.0", ] [[package]] @@ -4451,7 +4475,7 @@ dependencies = [ "fxhash", "hugr", "hugr-core", - "indexmap 2.13.0", + "indexmap 2.14.0", "itertools 0.14.0", "lazy_static", "num-rational", @@ -4496,7 +4520,7 @@ dependencies = [ "derive_more 2.1.1", "hugr", "hugr-core", - "indexmap 2.13.0", + "indexmap 2.14.0", "itertools 0.14.0", "lazy_static", "serde", @@ -4537,7 +4561,7 @@ version = "1.1.0+spec-1.1.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "f8195ca05e4eb728f4ba94f3e3291661320af739c4e43779cbdfae82ab239fcc" dependencies = [ - "indexmap 2.13.0", + "indexmap 2.14.0", "serde_core", "serde_spanned", "toml_datetime", @@ -4561,7 +4585,7 @@ version = "0.25.8+spec-1.1.0" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "16bff38f1d86c47f9ff0647e6838d7bb362522bdf44006c7068c2b1e606f1f3c" dependencies = [ - "indexmap 2.13.0", + "indexmap 2.14.0", "toml_datetime", "toml_parser", "winnow", @@ -4904,12 +4928,22 @@ dependencies = [ [[package]] name = "wasm-encoder" -version = "0.245.1" +version = "0.246.2" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "61fb705ce81adde29d2a8e99d87995e39a6e927358c91398f374474746070ef7" +dependencies = [ + "leb128fmt", + "wasmparser 0.246.2", +] + +[[package]] +name = "wasm-encoder" +version = "0.248.0" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "3f9dca005e69bf015e45577e415b9af8c67e8ee3c0e38b5b0add5aa92581ed5c" +checksum = "ac92cf547bc18d27ecc521015c08c353b4f18b84ab388bb6d1b6b682c620d9b6" dependencies = [ "leb128fmt", - "wasmparser 0.245.1", + "wasmparser 0.248.0", ] [[package]] @@ -4919,7 +4953,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "bb0e353e6a2fbdc176932bbaab493762eb1255a7900fe0fea1a2f96c296cc909" dependencies = [ "anyhow", - "indexmap 2.13.0", + "indexmap 2.14.0", "wasm-encoder 0.244.0", "wasmparser 0.244.0", ] @@ -4932,39 +4966,50 @@ checksum = "47b807c72e1bac69382b3a6fb3dbe8ea4c0ed87ff5629b8685ae6b9a611028fe" dependencies = [ "bitflags", "hashbrown 0.15.5", - "indexmap 2.13.0", + "indexmap 2.14.0", "semver", ] [[package]] name = "wasmparser" -version = "0.245.1" +version = "0.246.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "4f08c9adee0428b7bddf3890fc27e015ac4b761cc608c822667102b8bfd6995e" +checksum = "71cde4757396defafd25417cfb36aa3161027d06d865b0c24baaae229aac005d" dependencies = [ "bitflags", "hashbrown 0.16.1", - "indexmap 2.13.0", + "indexmap 2.14.0", "semver", "serde", ] +[[package]] +name = "wasmparser" +version = "0.248.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "aa4439c5eee9df71ee0c6efb37f63b1fcb1fec38f85f5142c54e7ed05d33091a" +dependencies = [ + "bitflags", + "indexmap 2.14.0", + "semver", +] + [[package]] name = "wasmprinter" -version = "0.245.1" +version = "0.246.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "5f41517a3716fbb8ccf46daa9c1325f760fcbff5168e75c7392288e410b91ac8" +checksum = "6e41f7493ba994b8a779430a4c25ff550fd5a40d291693af43a6ef48688f00e3" dependencies = [ "anyhow", "termcolor", - "wasmparser 0.245.1", + "wasmparser 0.246.2", ] [[package]] name = "wasmtime" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "efb1ed5899dde98357cfdcf647a4614498798719793898245b4b34e663addabf" +checksum = "372db8bbad8ec962038101f75ab2c3ffcd18797d7d3ae877a58ab9873cd0c4bd" dependencies = [ "addr2line", "async-trait", @@ -4985,7 +5030,7 @@ dependencies = [ "serde_derive", "smallvec", "target-lexicon", - "wasmparser 0.245.1", + "wasmparser 0.246.2", "wasmtime-environ", "wasmtime-internal-core", "wasmtime-internal-cranelift", @@ -5000,36 +5045,38 @@ dependencies = [ [[package]] name = "wasmtime-environ" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "4172382dcc785c31d0e862c6780a18f5dd437914d22c4691351f965ef751c821" +checksum = "1e15aa0d1545e48d9b25ca604e9e27b4cd6d5886d30ac5787b57b3a2daf85b57" dependencies = [ "anyhow", + "cpp_demangle", "cranelift-bforest", "cranelift-bitset", "cranelift-entity", "gimli", "hashbrown 0.16.1", - "indexmap 2.13.0", + "indexmap 2.14.0", "log", "object", "postcard", + "rustc-demangle", "serde", "serde_derive", "sha2 0.10.9", "smallvec", "target-lexicon", - "wasm-encoder 0.245.1", - "wasmparser 0.245.1", + "wasm-encoder 0.246.2", + "wasmparser 0.246.2", "wasmprinter", "wasmtime-internal-core", ] [[package]] name = "wasmtime-internal-core" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "9a3820b174f477d2a7083209d1ad5353fcdb11eaea434b2137b8681029460dd3" +checksum = "8f2c7fa6523647262bfb4095dbdf4087accefe525813e783f81a0c682f418ce4" dependencies = [ "hashbrown 0.16.1", "libm", @@ -5038,9 +5085,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-cranelift" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "d1679d205caf9766c6aa309d45bb3e7c634d7725e3164404df33824b9f7c4fb7" +checksum = "98c032f422e39061dfc43f32190c0a3526b04161ec4867f362958f3fe9d1fe29" dependencies = [ "cfg-if", "cranelift-codegen", @@ -5056,7 +5103,7 @@ dependencies = [ "smallvec", "target-lexicon", "thiserror 2.0.18", - "wasmparser 0.245.1", + "wasmparser 0.246.2", "wasmtime-environ", "wasmtime-internal-core", "wasmtime-internal-unwinder", @@ -5065,9 +5112,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-fiber" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "f1e505254058be5b0df458d670ee42d9eafe2349d04c1296e9dc01071dc20a85" +checksum = "d8dd76d80adf450cc260ba58f23c28030401930b19149695b1d121f7d621e791" dependencies = [ "cc", "cfg-if", @@ -5080,9 +5127,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-jit-debug" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "1c2e05b345f1773e59c20e6ad7298fd6857cdea245023d88bb659c96d8f0ea72" +checksum = "ab453cc600b28ee5d3f9495aa6d4cb2c81eda40903e9287296b548fba8b2391d" dependencies = [ "cc", "wasmtime-internal-versioned-export-macros", @@ -5090,9 +5137,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-jit-icache-coherence" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "b86701b234a4643e3f111869aa792b3a05a06e02d486ee9cb6c04dae16b52dab" +checksum = "6a1859e920871515d324fb9757c3e448d6ed1512ca6ccdff14b6e016505d6ada" dependencies = [ "cfg-if", "libc", @@ -5102,9 +5149,9 @@ dependencies = [ [[package]] name = "wasmtime-internal-unwinder" -version = "43.0.2" +version = "44.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "f63558d801beb83dde9b336eb4ae049019aee26627926edb32cd119d7e4c83cd" +checksum = 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+++++++++++++++++++++++++ crates/pecos-cli/src/cli/python_cmd.rs | 12 +++ crates/pecos-cli/src/main.rs | 16 +++ 5 files changed, 167 insertions(+) create mode 100644 crates/pecos-cli/src/cli/env_cmd.rs diff --git a/.github/workflows/python-release.yml b/.github/workflows/python-release.yml index 305fcfdf3..aafc427c1 100644 --- a/.github/workflows/python-release.yml +++ b/.github/workflows/python-release.yml @@ -221,6 +221,7 @@ jobs: PATH=$HOME/.cargo/bin:$HOME/.pecos/deps/llvm-14/bin:$PATH LLVM_SYS_140_PREFIX=$HOME/.pecos/deps/llvm-14 MACOSX_DEPLOYMENT_TARGET=13.2 + SDKROOT=$(xcrun --show-sdk-path) CIBW_BEFORE_ALL_MACOS: | curl -sSf https://sh.rustup.rs | sh -s -- -y source $HOME/.cargo/env @@ -289,6 +290,7 @@ jobs: PATH=$HOME/.cargo/bin:$HOME/.pecos/deps/llvm-14/bin:$PATH LLVM_SYS_140_PREFIX=$HOME/.pecos/deps/llvm-14 MACOSX_DEPLOYMENT_TARGET=13.2 + SDKROOT=$(xcrun --show-sdk-path) CIBW_BEFORE_ALL_MACOS: | source $HOME/.cargo/env 2>/dev/null || { curl -sSf https://sh.rustup.rs | sh -s -- -y && source $HOME/.cargo/env; } if [ ! -d "$HOME/.pecos/deps/llvm-14/bin" ]; then diff --git a/crates/pecos-cli/src/cli.rs b/crates/pecos-cli/src/cli.rs index f7e14a19f..7d2d5d2bf 100644 --- a/crates/pecos-cli/src/cli.rs +++ b/crates/pecos-cli/src/cli.rs @@ -11,6 +11,7 @@ pub mod cuda_cmd; pub mod cuquantum_cmd; +pub mod env_cmd; pub mod gpu_cmd; pub mod info; pub mod install_cmd; diff --git a/crates/pecos-cli/src/cli/env_cmd.rs b/crates/pecos-cli/src/cli/env_cmd.rs new file mode 100644 index 000000000..df3fc8ea2 --- /dev/null +++ b/crates/pecos-cli/src/cli/env_cmd.rs @@ -0,0 +1,136 @@ +// Copyright 2026 The PECOS Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except +// in compliance with the License. You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software distributed under the License +// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express +// or implied. See the License for the specific language governing permissions and limitations under +// the License. + +//! Implementation of the `env` subcommand. +//! +//! Prints the build environment variables for the current platform. This is +//! the single source of truth for platform-specific build configuration. +//! CI workflows, Justfile recipes, and `pecos python build` should all derive +//! their environment from this command. +//! +//! Usage: +//! eval $(pecos env) # bash/zsh — set variables in current shell +//! pecos env --format json # machine-readable output +//! pecos env --show # human-readable display + +use pecos_build::Result; +use std::collections::BTreeMap; + +/// Collect the build environment for the current platform. +/// +/// Returns a map of environment variable names to values. Only includes +/// variables that PECOS needs to set — does not duplicate the entire shell +/// environment. +pub fn collect_env() -> Result> { + let mut env = BTreeMap::new(); + + // LLVM + if let Some(llvm_path) = pecos_build::llvm::find_llvm_14(None) { + let llvm_str = llvm_path.display().to_string(); + env.insert("LLVM_SYS_140_PREFIX".into(), llvm_str.clone()); + + // Add LLVM bin to PATH suggestion + let bin_path = llvm_path.join("bin"); + if bin_path.exists() { + let current_path = std::env::var("PATH").unwrap_or_default(); + env.insert( + "PATH".into(), + format!("{}:{current_path}", bin_path.display()), + ); + } + } + + // macOS-specific + #[cfg(target_os = "macos")] + { + // SDKROOT — needed for bindgen/clang to find system headers + if std::env::var("SDKROOT").is_err() { + if let Ok(output) = std::process::Command::new("xcrun") + .args(["--show-sdk-path"]) + .output() + && output.status.success() + { + let sdk = String::from_utf8_lossy(&output.stdout).trim().to_string(); + if !sdk.is_empty() { + env.insert("SDKROOT".into(), sdk); + } + } + } + + // Deployment target + env.insert("MACOSX_DEPLOYMENT_TARGET".into(), "13.2".into()); + } + + // CUDA + if let Some(cuda_path) = pecos_build::cuda::find_cuda() { + env.insert("CUDA_PATH".into(), cuda_path.display().to_string()); + } + + // cuQuantum + if let Some(cuquantum_path) = pecos_build::cuquantum::find_cuquantum() { + env.insert( + "CUQUANTUM_ROOT".into(), + cuquantum_path.display().to_string(), + ); + } + + Ok(env) +} + +/// Print environment in shell-eval format: `export KEY="VALUE"` +pub fn print_shell(env: &BTreeMap) { + for (key, value) in env { + println!("export {key}=\"{value}\""); + } +} + +/// Print environment in JSON format. +pub fn print_json(env: &BTreeMap) { + println!("{}", serde_json::to_string_pretty(env).unwrap_or_else(|_| { + // Fallback if serde_json isn't available — manual JSON + let mut out = String::from("{\n"); + for (i, (key, value)) in env.iter().enumerate() { + let escaped = value.replace('\\', "\\\\").replace('"', "\\\""); + out.push_str(&format!(" \"{key}\": \"{escaped}\"")); + if i + 1 < env.len() { + out.push(','); + } + out.push('\n'); + } + out.push('}'); + out + })); +} + +/// Print environment in human-readable format. +pub fn print_show(env: &BTreeMap) { + if env.is_empty() { + println!("No PECOS-specific environment variables needed."); + return; + } + println!("PECOS build environment:"); + for (key, value) in env { + println!(" {key}={value}"); + } +} + +/// Run the env subcommand. +pub fn run(format: &str) -> Result<()> { + let env = collect_env()?; + match format { + "shell" => print_shell(&env), + "json" => print_json(&env), + "show" => print_show(&env), + _ => print_shell(&env), + } + Ok(()) +} diff --git a/crates/pecos-cli/src/cli/python_cmd.rs b/crates/pecos-cli/src/cli/python_cmd.rs index aecc765b9..ad79168d9 100644 --- a/crates/pecos-cli/src/cli/python_cmd.rs +++ b/crates/pecos-cli/src/cli/python_cmd.rs @@ -151,6 +151,18 @@ fn run_build(profile: &str, rustflags: Option<&str>, cuda: bool) -> Result<()> { cmd.env("LIBRARY_PATH", "/usr/lib"); } + // Apply PECOS build environment (SDKROOT, LLVM, CUDA, etc.) + // This is the single source of truth — same logic as `pecos env`. + if let Ok(build_env) = super::env_cmd::collect_env() { + for (key, value) in &build_env { + // Don't override PATH — we already set it above with venv + // Don't override LLVM_SYS_140_PREFIX if already in flags + if key != "PATH" { + cmd.env(key, value); + } + } + } + let status = cmd.status(); match status { Ok(s) if s.success() => {} diff --git a/crates/pecos-cli/src/main.rs b/crates/pecos-cli/src/main.rs index 3e58d5619..e55c5929c 100644 --- a/crates/pecos-cli/src/main.rs +++ b/crates/pecos-cli/src/main.rs @@ -112,6 +112,21 @@ enum Commands { #[command(subcommand)] command: DepsCommands, }, + /// Print build environment variables for the current platform + /// + /// Use `eval $(pecos env)` in bash/zsh to set variables in the current + /// shell. All platform-specific build configuration (LLVM paths, SDKROOT, + /// CUDA, cuQuantum) is detected and printed. + /// + /// Example: eval $(pecos env) + /// Example: pecos env --format show + /// Example: pecos env --format json + Env { + /// Output format: shell (default), json, show + #[arg(long, default_value = "shell")] + format: String, + }, + /// Set up build environment (detect and install missing dependencies) /// /// Interactively checks for LLVM, CUDA, and cuQuantum and offers to @@ -677,6 +692,7 @@ fn main() -> Result<(), Box> { Commands::Llvm { command } => cli::llvm_cmd::run(command.clone())?, Commands::Selene { command } => cli::selene_cmd::run(command.clone())?, Commands::Deps { command } => cli::manifest_cmd::run(command.clone())?, + Commands::Env { format } => cli::env_cmd::run(&format)?, Commands::Setup { yes, no, From da37544a488e49587b55ffeac131f08e02d49458 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 22:40:00 -0600 Subject: [PATCH 120/125] Apply lint fixes to pecos env command --- crates/pecos-cli/src/cli/env_cmd.rs | 29 ++++++++++++++++------------- crates/pecos-cli/src/main.rs | 2 +- 2 files changed, 17 insertions(+), 14 deletions(-) diff --git a/crates/pecos-cli/src/cli/env_cmd.rs b/crates/pecos-cli/src/cli/env_cmd.rs index df3fc8ea2..1eec5f40a 100644 --- a/crates/pecos-cli/src/cli/env_cmd.rs +++ b/crates/pecos-cli/src/cli/env_cmd.rs @@ -95,20 +95,23 @@ pub fn print_shell(env: &BTreeMap) { /// Print environment in JSON format. pub fn print_json(env: &BTreeMap) { - println!("{}", serde_json::to_string_pretty(env).unwrap_or_else(|_| { - // Fallback if serde_json isn't available — manual JSON - let mut out = String::from("{\n"); - for (i, (key, value)) in env.iter().enumerate() { - let escaped = value.replace('\\', "\\\\").replace('"', "\\\""); - out.push_str(&format!(" \"{key}\": \"{escaped}\"")); - if i + 1 < env.len() { - out.push(','); + println!( + "{}", + serde_json::to_string_pretty(env).unwrap_or_else(|_| { + // Fallback if serde_json isn't available — manual JSON + let mut out = String::from("{\n"); + for (i, (key, value)) in env.iter().enumerate() { + let escaped = value.replace('\\', "\\\\").replace('"', "\\\""); + out.push_str(&format!(" \"{key}\": \"{escaped}\"")); + if i + 1 < env.len() { + out.push(','); + } + out.push('\n'); } - out.push('\n'); - } - out.push('}'); - out - })); + out.push('}'); + out + }) + ); } /// Print environment in human-readable format. diff --git a/crates/pecos-cli/src/main.rs b/crates/pecos-cli/src/main.rs index e55c5929c..a9579be81 100644 --- a/crates/pecos-cli/src/main.rs +++ b/crates/pecos-cli/src/main.rs @@ -692,7 +692,7 @@ fn main() -> Result<(), Box> { Commands::Llvm { command } => cli::llvm_cmd::run(command.clone())?, Commands::Selene { command } => cli::selene_cmd::run(command.clone())?, Commands::Deps { command } => cli::manifest_cmd::run(command.clone())?, - Commands::Env { format } => cli::env_cmd::run(&format)?, + Commands::Env { format } => cli::env_cmd::run(format)?, Commands::Setup { yes, no, From 6f5097a7a84990efa97c34a58e7db4f352eed034 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Mon, 11 May 2026 23:06:11 -0600 Subject: [PATCH 121/125] Fix clippy errors in pecos env command --- crates/pecos-cli/src/cli/env_cmd.rs | 44 +++++++++++--------------- crates/pecos-cli/src/cli/python_cmd.rs | 12 +++---- crates/pecos-cli/src/main.rs | 2 +- 3 files changed, 24 insertions(+), 34 deletions(-) diff --git a/crates/pecos-cli/src/cli/env_cmd.rs b/crates/pecos-cli/src/cli/env_cmd.rs index 1eec5f40a..712dfb6da 100644 --- a/crates/pecos-cli/src/cli/env_cmd.rs +++ b/crates/pecos-cli/src/cli/env_cmd.rs @@ -22,23 +22,23 @@ //! pecos env --format json # machine-readable output //! pecos env --show # human-readable display -use pecos_build::Result; use std::collections::BTreeMap; +use std::fmt::Write; /// Collect the build environment for the current platform. /// /// Returns a map of environment variable names to values. Only includes /// variables that PECOS needs to set — does not duplicate the entire shell /// environment. -pub fn collect_env() -> Result> { +pub fn collect_env() -> BTreeMap { let mut env = BTreeMap::new(); // LLVM if let Some(llvm_path) = pecos_build::llvm::find_llvm_14(None) { let llvm_str = llvm_path.display().to_string(); - env.insert("LLVM_SYS_140_PREFIX".into(), llvm_str.clone()); + env.insert("LLVM_SYS_140_PREFIX".into(), llvm_str); - // Add LLVM bin to PATH suggestion + // Add LLVM bin to PATH let bin_path = llvm_path.join("bin"); if bin_path.exists() { let current_path = std::env::var("PATH").unwrap_or_default(); @@ -83,7 +83,7 @@ pub fn collect_env() -> Result> { ); } - Ok(env) + env } /// Print environment in shell-eval format: `export KEY="VALUE"` @@ -95,23 +95,17 @@ pub fn print_shell(env: &BTreeMap) { /// Print environment in JSON format. pub fn print_json(env: &BTreeMap) { - println!( - "{}", - serde_json::to_string_pretty(env).unwrap_or_else(|_| { - // Fallback if serde_json isn't available — manual JSON - let mut out = String::from("{\n"); - for (i, (key, value)) in env.iter().enumerate() { - let escaped = value.replace('\\', "\\\\").replace('"', "\\\""); - out.push_str(&format!(" \"{key}\": \"{escaped}\"")); - if i + 1 < env.len() { - out.push(','); - } - out.push('\n'); - } - out.push('}'); - out - }) - ); + let mut out = String::from("{\n"); + for (i, (key, value)) in env.iter().enumerate() { + let escaped = value.replace('\\', "\\\\").replace('"', "\\\""); + let _ = write!(out, " \"{key}\": \"{escaped}\""); + if i + 1 < env.len() { + out.push(','); + } + out.push('\n'); + } + out.push('}'); + println!("{out}"); } /// Print environment in human-readable format. @@ -127,13 +121,11 @@ pub fn print_show(env: &BTreeMap) { } /// Run the env subcommand. -pub fn run(format: &str) -> Result<()> { - let env = collect_env()?; +pub fn run(format: &str) { + let env = collect_env(); match format { - "shell" => print_shell(&env), "json" => print_json(&env), "show" => print_show(&env), _ => print_shell(&env), } - Ok(()) } diff --git a/crates/pecos-cli/src/cli/python_cmd.rs b/crates/pecos-cli/src/cli/python_cmd.rs index ad79168d9..c37cac0ad 100644 --- a/crates/pecos-cli/src/cli/python_cmd.rs +++ b/crates/pecos-cli/src/cli/python_cmd.rs @@ -153,13 +153,11 @@ fn run_build(profile: &str, rustflags: Option<&str>, cuda: bool) -> Result<()> { // Apply PECOS build environment (SDKROOT, LLVM, CUDA, etc.) // This is the single source of truth — same logic as `pecos env`. - if let Ok(build_env) = super::env_cmd::collect_env() { - for (key, value) in &build_env { - // Don't override PATH — we already set it above with venv - // Don't override LLVM_SYS_140_PREFIX if already in flags - if key != "PATH" { - cmd.env(key, value); - } + let build_env = super::env_cmd::collect_env(); + for (key, value) in &build_env { + // Don't override PATH — we already set it above with venv + if key != "PATH" { + cmd.env(key, value); } } diff --git a/crates/pecos-cli/src/main.rs b/crates/pecos-cli/src/main.rs index a9579be81..27f203b7e 100644 --- a/crates/pecos-cli/src/main.rs +++ b/crates/pecos-cli/src/main.rs @@ -692,7 +692,7 @@ fn main() -> Result<(), Box> { Commands::Llvm { command } => cli::llvm_cmd::run(command.clone())?, Commands::Selene { command } => cli::selene_cmd::run(command.clone())?, Commands::Deps { command } => cli::manifest_cmd::run(command.clone())?, - Commands::Env { format } => cli::env_cmd::run(format)?, + Commands::Env { format } => cli::env_cmd::run(format), Commands::Setup { yes, no, From f7a15f9aa805f21674bed53055e629cab986e623 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Tue, 12 May 2026 08:23:00 -0600 Subject: [PATCH 122/125] Fix CI failures: Tesseract MSVC build, Python 3.10 tomli, doc test guppy --- Justfile | 2 +- crates/pecos-tesseract/build_tesseract.rs | 26 ++++++++--- pyproject.toml | 1 + .../pecos/test_selene_plugin_workspace.py | 2 +- scripts/docs/test_working_examples.py | 43 ++++++++++++++----- uv.lock | 2 + 6 files changed, 58 insertions(+), 18 deletions(-) diff --git a/Justfile b/Justfile index b395b7289..c05a2600f 100644 --- a/Justfile +++ b/Justfile @@ -248,7 +248,7 @@ check: # Check Python workspace metadata [group('lint')] python-workspace-check: - @if command -v python3 >/dev/null 2>&1; then python3 scripts/check_python_workspace.py; else python scripts/check_python_workspace.py; fi + @uv run python scripts/check_python_workspace.py # Run cargo clippy (CUDA-aware: uses --all-features only when CUDA is available) [group('lint')] diff --git a/crates/pecos-tesseract/build_tesseract.rs b/crates/pecos-tesseract/build_tesseract.rs index a9f7f3966..9ed16962c 100644 --- a/crates/pecos-tesseract/build_tesseract.rs +++ b/crates/pecos-tesseract/build_tesseract.rs @@ -2,6 +2,7 @@ use pecos_build::{Manifest, Result, check_cxx20_toolchain, ensure_dep_ready, report_cache_config}; use std::env; +use std::fs; use std::path::{Path, PathBuf}; // Use the shared modules from the parent @@ -88,9 +89,23 @@ fn build_cxx_bridge(tesseract_dir: &Path, stim_dir: &Path, boost_dir: &Path) { build .file(tesseract_src_dir.join("common.cc")) .file(tesseract_src_dir.join("utils.cc")) - .file(tesseract_src_dir.join("visualization.cc")) .file(tesseract_src_dir.join("tesseract.cc")); + // visualization.cc uses std::min(3ul, vec.size()). On MSVC Win64, + // unsigned long is 32-bit and size_t is 64-bit, so std::min template + // deduction fails. Patch the source to use size_t{3} instead. + let vis_src = tesseract_src_dir.join("visualization.cc"); + let vis_content = fs::read_to_string(&vis_src).expect("read visualization.cc"); + if vis_content.contains("std::min(3ul,") { + let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap()); + let patched = out_dir.join("visualization_patched.cc"); + let fixed = vis_content.replace("std::min(3ul,", "std::min(size_t{3},"); + fs::write(&patched, fixed).expect("write patched visualization.cc"); + build.file(patched); + } else { + build.file(vis_src); + } + // Configure build build .std("c++20") @@ -149,10 +164,11 @@ fn build_cxx_bridge(tesseract_dir: &Path, stim_dir: &Path, boost_dir: &Path) { .flag_if_supported("/permissive-") .flag_if_supported("/Zc:__cplusplus"); - // Force include standard headers that external libraries assume are available - // MSVC is stricter than GCC/Clang about transitive includes - build.flag("/FI").flag("array"); // For std::array - build.flag("/FI").flag("numeric"); // For std::iota + // Force include standard headers that vendored code assumes are + // transitively available. MSVC is stricter than GCC/Clang. + build.flag("/FI").flag("array"); + build.flag("/FI").flag("numeric"); + build.flag("/FI").flag("algorithm"); } build.compile("tesseract-bridge"); diff --git a/pyproject.toml b/pyproject.toml index 0b973b433..3bde0ac88 100644 --- a/pyproject.toml +++ b/pyproject.toml @@ -38,6 +38,7 @@ dev = [ "pre-commit", # Git hooks "black", # Code formatting "ruff", # Fast Python linting + "tomli>=1.1.0; python_version < '3.11'", # TOML parsing (stdlib in 3.11+) "mkdocs", # Documentation framework "mkdocs-material", # Material theme for MkDocs "mkdocstrings[python]", # Code documentation extraction diff --git a/python/quantum-pecos/tests/pecos/test_selene_plugin_workspace.py b/python/quantum-pecos/tests/pecos/test_selene_plugin_workspace.py index 822518776..60e5fcb12 100644 --- a/python/quantum-pecos/tests/pecos/test_selene_plugin_workspace.py +++ b/python/quantum-pecos/tests/pecos/test_selene_plugin_workspace.py @@ -7,7 +7,7 @@ try: import tomllib except ModuleNotFoundError: # pragma: no cover - import tomli as tomllib + import tomli as tomllib # type: ignore[no-redef] def _repo_root() -> Path: diff --git a/scripts/docs/test_working_examples.py b/scripts/docs/test_working_examples.py index f7b37f6e0..3f80e22d0 100755 --- a/scripts/docs/test_working_examples.py +++ b/scripts/docs/test_working_examples.py @@ -26,8 +26,8 @@ import tempfile from pathlib import Path -# Import shared extraction function from test_code_examples -from test_code_examples import extract_code_blocks +# Import shared functions from test_code_examples +from test_code_examples import _uses_guppy_decorator, extract_code_blocks # Files to test (relative to the docs directory) TEST_FILES = [ @@ -52,15 +52,36 @@ def test_python_block( print(f"Testing Python block #{block_number} from {file_path}...") try: - # Execute the code block and capture output - result = subprocess.run( - [sys.executable, "-c", code_block], - capture_output=True, - text=True, - timeout=30, - check=False, - shell=False, - ) + # Guppy code needs to be in a file for inspect.getsourcelines() to work + if _uses_guppy_decorator(code_block): + with tempfile.NamedTemporaryFile( + mode="w", + suffix=".py", + delete=False, + encoding="utf-8", + ) as f: + f.write(code_block) + temp_path = f.name + try: + result = subprocess.run( + [sys.executable, temp_path], + capture_output=True, + text=True, + timeout=60, + check=False, + shell=False, + ) + finally: + Path(temp_path).unlink(missing_ok=True) + else: + result = subprocess.run( + [sys.executable, "-c", code_block], + capture_output=True, + text=True, + timeout=30, + check=False, + shell=False, + ) if result.returncode != 0: print(f"FAIL: Error in Python block #{block_number} from {file_path}:") diff --git a/uv.lock b/uv.lock index b65241ece..7511c093b 100644 --- a/uv.lock +++ b/uv.lock @@ -2933,6 +2933,7 @@ dev = [ { name = "pre-commit" }, { name = "ruff" }, { name = "setuptools" }, + { name = "tomli", marker = "python_full_version < '3.11'" }, ] examples = [ { name = "jupyter" }, @@ -2970,6 +2971,7 @@ dev = [ { name = "pre-commit" }, { name = "ruff" }, { name = "setuptools", specifier = ">=82.0.1" }, + { name = "tomli", marker = "python_full_version < '3.11'", specifier = ">=1.1.0" }, ] examples = [ { name = "jupyter", specifier = ">=1.1.1" }, From d86f16d5d01e724411d496b19485cb09b417bd16 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Tue, 12 May 2026 10:27:18 -0600 Subject: [PATCH 123/125] Fix macOS clippy collapsible-if and add pecos-rslib-exp to release workflow --- .github/workflows/python-release.yml | 80 +++++++++++++++++++++++++++- crates/pecos-cli/src/cli/env_cmd.rs | 15 +++--- 2 files changed, 85 insertions(+), 10 deletions(-) diff --git a/.github/workflows/python-release.yml b/.github/workflows/python-release.yml index aafc427c1..f7b2953c4 100644 --- a/.github/workflows/python-release.yml +++ b/.github/workflows/python-release.yml @@ -324,6 +324,68 @@ jobs: name: wheel-pecos-rslib-llvm-${{ matrix.os }}-${{ matrix.architecture }} path: ./wheelhouse-llvm/*.whl + # Build pecos-rslib-exp wheel (reuses Rust and LLVM from pecos-rslib build) + - name: Build pecos-rslib-exp wheels + uses: pypa/cibuildwheel@v3.3.1 + with: + package-dir: python/pecos-rslib-exp + output-dir: wheelhouse-exp + env: + CIBW_BUILD: "cp310-*" + CIBW_SKIP: "*-win32 *-manylinux_i686 *-musllinux*" + CIBW_BUILD_VERBOSITY: "1" + CIBW_ARCHS_LINUX: ${{ matrix.cibw_archs }} + CIBW_MANYLINUX_X86_64_IMAGE: "manylinux_2_28" + CIBW_MANYLINUX_AARCH64_IMAGE: "manylinux_2_28" + CIBW_ENVIRONMENT_LINUX: > + PATH=$HOME/.cargo/bin:$HOME/.pecos/deps/llvm-14/bin:$PATH + LLVM_SYS_140_PREFIX=$HOME/.pecos/deps/llvm-14 + CIBW_BEFORE_ALL_LINUX: | + curl -sSf https://sh.rustup.rs | sh -s -- -y + source $HOME/.cargo/env + dnf install libffi-devel -y + cargo run --release -p pecos-cli -- install llvm --force + CIBW_REPAIR_WHEEL_COMMAND_LINUX: > + auditwheel repair -w {dest_dir} {wheel} && + pipx run abi3audit --strict --report {wheel} + CIBW_ENVIRONMENT_MACOS: > + PATH=$HOME/.cargo/bin:$HOME/.pecos/deps/llvm-14/bin:$PATH + LLVM_SYS_140_PREFIX=$HOME/.pecos/deps/llvm-14 + MACOSX_DEPLOYMENT_TARGET=13.2 + SDKROOT=$(xcrun --show-sdk-path) + CIBW_BEFORE_ALL_MACOS: | + source $HOME/.cargo/env 2>/dev/null || { curl -sSf https://sh.rustup.rs | sh -s -- -y && source $HOME/.cargo/env; } + if [ ! -d "$HOME/.pecos/deps/llvm-14/bin" ]; then + rustup update + cargo run --release -p pecos-cli -- install llvm --force + else + echo "LLVM already installed from pecos-rslib build, skipping" + fi + mkdir -p $HOME/.pecos/bin + printf '#!/bin/bash\nunset DYLD_LIBRARY_PATH\nexec /usr/bin/codesign "$@"\n' > $HOME/.pecos/bin/codesign + chmod +x $HOME/.pecos/bin/codesign + CIBW_REPAIR_WHEEL_COMMAND_MACOS: > + PATH=$HOME/.pecos/bin:$PATH DYLD_LIBRARY_PATH=$HOME/.pecos/deps/llvm-14/lib delocate-wheel --require-archs {delocate_archs} -w {dest_dir} -v {wheel} && + pipx run abi3audit --strict --report {wheel} + CIBW_ENVIRONMENT_WINDOWS: > + PATH="C:\\Users\\runneradmin\\.pecos\\deps\\llvm-14\\bin;$PATH" + LLVM_SYS_140_PREFIX="C:\\Users\\runneradmin\\.pecos\\deps\\llvm-14" + CIBW_BEFORE_ALL_WINDOWS: > + rustup update && + if not exist "C:\Users\runneradmin\.pecos\deps\llvm-14\bin" (cargo run --release -p pecos-cli -- install llvm --force) else (echo LLVM already installed from pecos-rslib build) + CIBW_BEFORE_BUILD_WINDOWS: > + pip install delvewheel && + python -c "import delvewheel._dll_list as d,inspect,re as r;p=inspect.getfile(d);c=open(p).read();n=chr(10);open(p,'w').write(c.replace(r\"re.compile('api-.*'),\",r\"re.compile('api-.*'),\"+n+r\" re.compile('ext-.*'),\")) if 'ext-.*' not in c else None" + CIBW_REPAIR_WHEEL_COMMAND_WINDOWS: > + delvewheel repair -v --add-path "C:\\Users\\runneradmin\\.pecos\\deps\\llvm-14\\bin" --no-dll "combase.dll;rmclient.dll" -w {dest_dir} {wheel} && + pipx run abi3audit --strict --report {wheel} + + - name: Upload pecos-rslib-exp wheels + uses: actions/upload-artifact@v7 + with: + name: wheel-pecos-rslib-exp-${{ matrix.os }}-${{ matrix.architecture }} + path: ./wheelhouse-exp/*.whl + test_abi3_wheels: needs: build_wheelspecos_rslib if: | @@ -431,10 +493,17 @@ jobs: name: wheel-pecos-rslib-llvm-ubuntu-latest-x86_64 path: ./pecos-rslib-llvm-wheel - - name: Install pecos-rslib and pecos-rslib-llvm + - name: Download pecos-rslib-exp wheel + uses: actions/download-artifact@v7 + with: + name: wheel-pecos-rslib-exp-ubuntu-latest-x86_64 + path: ./pecos-rslib-exp-wheel + + - name: Install pecos-rslib, pecos-rslib-llvm, and pecos-rslib-exp run: | pip install ./pecos-rslib-wheel/*.whl pip install ./pecos-rslib-llvm-wheel/*.whl + pip install ./pecos-rslib-exp-wheel/*.whl - name: Install build dependencies run: pip install build @@ -484,10 +553,17 @@ jobs: name: wheel-pecos-rslib-llvm-ubuntu-latest-x86_64 path: ./pecos-rslib-llvm-wheel - - name: Install pecos-rslib and pecos-rslib-llvm + - name: Download pecos-rslib-exp wheel + uses: actions/download-artifact@v7 + with: + name: wheel-pecos-rslib-exp-ubuntu-latest-x86_64 + path: ./pecos-rslib-exp-wheel + + - name: Install pecos-rslib, pecos-rslib-llvm, and pecos-rslib-exp run: | pip install ./pecos-rslib-wheel/*.whl pip install ./pecos-rslib-llvm-wheel/*.whl + pip install ./pecos-rslib-exp-wheel/*.whl - name: Install build dependencies run: pip install build diff --git a/crates/pecos-cli/src/cli/env_cmd.rs b/crates/pecos-cli/src/cli/env_cmd.rs index 712dfb6da..4f8007142 100644 --- a/crates/pecos-cli/src/cli/env_cmd.rs +++ b/crates/pecos-cli/src/cli/env_cmd.rs @@ -53,16 +53,15 @@ pub fn collect_env() -> BTreeMap { #[cfg(target_os = "macos")] { // SDKROOT — needed for bindgen/clang to find system headers - if std::env::var("SDKROOT").is_err() { - if let Ok(output) = std::process::Command::new("xcrun") + if std::env::var("SDKROOT").is_err() + && let Ok(output) = std::process::Command::new("xcrun") .args(["--show-sdk-path"]) .output() - && output.status.success() - { - let sdk = String::from_utf8_lossy(&output.stdout).trim().to_string(); - if !sdk.is_empty() { - env.insert("SDKROOT".into(), sdk); - } + && output.status.success() + { + let sdk = String::from_utf8_lossy(&output.stdout).trim().to_string(); + if !sdk.is_empty() { + env.insert("SDKROOT".into(), sdk); } } From 05d155a855081ab732cd48cd92af22402b78d6d6 Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Tue, 12 May 2026 10:41:07 -0600 Subject: [PATCH 124/125] Remove quantum-pecos dependency on pecos-rslib-exp --- .github/workflows/python-release.yml | 82 +--------------------- python/quantum-pecos/pyproject.toml | 2 - python/quantum-pecos/src/pecos/__init__.py | 21 +----- uv.lock | 2 - 4 files changed, 3 insertions(+), 104 deletions(-) diff --git a/.github/workflows/python-release.yml b/.github/workflows/python-release.yml index f7b2953c4..a672ae10d 100644 --- a/.github/workflows/python-release.yml +++ b/.github/workflows/python-release.yml @@ -182,7 +182,6 @@ jobs: # Build configuration CIBW_BUILD: "cp310-*" CIBW_SKIP: "*-win32 *-manylinux_i686 *-musllinux*" - CIBW_BUILD_VERBOSITY: "1" CIBW_ARCHS_LINUX: ${{ matrix.cibw_archs }} CIBW_MANYLINUX_X86_64_IMAGE: "manylinux_2_28" CIBW_MANYLINUX_AARCH64_IMAGE: "manylinux_2_28" @@ -271,7 +270,6 @@ jobs: env: CIBW_BUILD: "cp310-*" CIBW_SKIP: "*-win32 *-manylinux_i686 *-musllinux*" - CIBW_BUILD_VERBOSITY: "1" CIBW_ARCHS_LINUX: ${{ matrix.cibw_archs }} CIBW_MANYLINUX_X86_64_IMAGE: "manylinux_2_28" CIBW_MANYLINUX_AARCH64_IMAGE: "manylinux_2_28" @@ -324,68 +322,6 @@ jobs: name: wheel-pecos-rslib-llvm-${{ matrix.os }}-${{ matrix.architecture }} path: ./wheelhouse-llvm/*.whl - # Build pecos-rslib-exp wheel (reuses Rust and LLVM from pecos-rslib build) - - name: Build pecos-rslib-exp wheels - uses: pypa/cibuildwheel@v3.3.1 - with: - package-dir: python/pecos-rslib-exp - output-dir: wheelhouse-exp - env: - CIBW_BUILD: "cp310-*" - CIBW_SKIP: "*-win32 *-manylinux_i686 *-musllinux*" - CIBW_BUILD_VERBOSITY: "1" - CIBW_ARCHS_LINUX: ${{ matrix.cibw_archs }} - CIBW_MANYLINUX_X86_64_IMAGE: "manylinux_2_28" - CIBW_MANYLINUX_AARCH64_IMAGE: "manylinux_2_28" - CIBW_ENVIRONMENT_LINUX: > - PATH=$HOME/.cargo/bin:$HOME/.pecos/deps/llvm-14/bin:$PATH - LLVM_SYS_140_PREFIX=$HOME/.pecos/deps/llvm-14 - CIBW_BEFORE_ALL_LINUX: | - curl -sSf https://sh.rustup.rs | sh -s -- -y - source $HOME/.cargo/env - dnf install libffi-devel -y - cargo run --release -p pecos-cli -- install llvm --force - CIBW_REPAIR_WHEEL_COMMAND_LINUX: > - auditwheel repair -w {dest_dir} {wheel} && - pipx run abi3audit --strict --report {wheel} - CIBW_ENVIRONMENT_MACOS: > - PATH=$HOME/.cargo/bin:$HOME/.pecos/deps/llvm-14/bin:$PATH - LLVM_SYS_140_PREFIX=$HOME/.pecos/deps/llvm-14 - MACOSX_DEPLOYMENT_TARGET=13.2 - SDKROOT=$(xcrun --show-sdk-path) - CIBW_BEFORE_ALL_MACOS: | - source $HOME/.cargo/env 2>/dev/null || { curl -sSf https://sh.rustup.rs | sh -s -- -y && source $HOME/.cargo/env; } - if [ ! -d "$HOME/.pecos/deps/llvm-14/bin" ]; then - rustup update - cargo run --release -p pecos-cli -- install llvm --force - else - echo "LLVM already installed from pecos-rslib build, skipping" - fi - mkdir -p $HOME/.pecos/bin - printf '#!/bin/bash\nunset DYLD_LIBRARY_PATH\nexec /usr/bin/codesign "$@"\n' > $HOME/.pecos/bin/codesign - chmod +x $HOME/.pecos/bin/codesign - CIBW_REPAIR_WHEEL_COMMAND_MACOS: > - PATH=$HOME/.pecos/bin:$PATH DYLD_LIBRARY_PATH=$HOME/.pecos/deps/llvm-14/lib delocate-wheel --require-archs {delocate_archs} -w {dest_dir} -v {wheel} && - pipx run abi3audit --strict --report {wheel} - CIBW_ENVIRONMENT_WINDOWS: > - PATH="C:\\Users\\runneradmin\\.pecos\\deps\\llvm-14\\bin;$PATH" - LLVM_SYS_140_PREFIX="C:\\Users\\runneradmin\\.pecos\\deps\\llvm-14" - CIBW_BEFORE_ALL_WINDOWS: > - rustup update && - if not exist "C:\Users\runneradmin\.pecos\deps\llvm-14\bin" (cargo run --release -p pecos-cli -- install llvm --force) else (echo LLVM already installed from pecos-rslib build) - CIBW_BEFORE_BUILD_WINDOWS: > - pip install delvewheel && - python -c "import delvewheel._dll_list as d,inspect,re as r;p=inspect.getfile(d);c=open(p).read();n=chr(10);open(p,'w').write(c.replace(r\"re.compile('api-.*'),\",r\"re.compile('api-.*'),\"+n+r\" re.compile('ext-.*'),\")) if 'ext-.*' not in c else None" - CIBW_REPAIR_WHEEL_COMMAND_WINDOWS: > - delvewheel repair -v --add-path "C:\\Users\\runneradmin\\.pecos\\deps\\llvm-14\\bin" --no-dll "combase.dll;rmclient.dll" -w {dest_dir} {wheel} && - pipx run abi3audit --strict --report {wheel} - - - name: Upload pecos-rslib-exp wheels - uses: actions/upload-artifact@v7 - with: - name: wheel-pecos-rslib-exp-${{ matrix.os }}-${{ matrix.architecture }} - path: ./wheelhouse-exp/*.whl - test_abi3_wheels: needs: build_wheelspecos_rslib if: | @@ -493,17 +429,10 @@ jobs: name: wheel-pecos-rslib-llvm-ubuntu-latest-x86_64 path: ./pecos-rslib-llvm-wheel - - name: Download pecos-rslib-exp wheel - uses: actions/download-artifact@v7 - with: - name: wheel-pecos-rslib-exp-ubuntu-latest-x86_64 - path: ./pecos-rslib-exp-wheel - - - name: Install pecos-rslib, pecos-rslib-llvm, and pecos-rslib-exp + - name: Install pecos-rslib and pecos-rslib-llvm run: | pip install ./pecos-rslib-wheel/*.whl pip install ./pecos-rslib-llvm-wheel/*.whl - pip install ./pecos-rslib-exp-wheel/*.whl - name: Install build dependencies run: pip install build @@ -553,17 +482,10 @@ jobs: name: wheel-pecos-rslib-llvm-ubuntu-latest-x86_64 path: ./pecos-rslib-llvm-wheel - - name: Download pecos-rslib-exp wheel - uses: actions/download-artifact@v7 - with: - name: wheel-pecos-rslib-exp-ubuntu-latest-x86_64 - path: ./pecos-rslib-exp-wheel - - - name: Install pecos-rslib, pecos-rslib-llvm, and pecos-rslib-exp + - name: Install pecos-rslib and pecos-rslib-llvm run: | pip install ./pecos-rslib-wheel/*.whl pip install ./pecos-rslib-llvm-wheel/*.whl - pip install ./pecos-rslib-exp-wheel/*.whl - name: Install build dependencies run: pip install build diff --git a/python/quantum-pecos/pyproject.toml b/python/quantum-pecos/pyproject.toml index f5829b8ee..1d22357c1 100644 --- a/python/quantum-pecos/pyproject.toml +++ b/python/quantum-pecos/pyproject.toml @@ -29,7 +29,6 @@ license = { file = "LICENSE"} keywords = ["quantum", "QEC", "simulation", "PECOS"] dependencies = [ "pecos-rslib==0.8.0.dev8", - "pecos-rslib-exp==0.8.0.dev8", "pecos-rslib-llvm==0.8.0.dev8", "phir>=0.3.3", "networkx>=2.1.0", @@ -89,7 +88,6 @@ cuda = [ [tool.uv.sources] pecos-rslib = { workspace = true } -pecos-rslib-exp = { workspace = true } pecos-rslib-llvm = { workspace = true } pecos-rslib-cuda = { workspace = true } diff --git a/python/quantum-pecos/src/pecos/__init__.py b/python/quantum-pecos/src/pecos/__init__.py index f020f7905..c7c7f7af9 100644 --- a/python/quantum-pecos/src/pecos/__init__.py +++ b/python/quantum-pecos/src/pecos/__init__.py @@ -31,7 +31,6 @@ from typing import TYPE_CHECKING import pecos_rslib -import pecos_rslib_exp from pecos_rslib import ( AngleSource, # Angle source specification for gate decomposition Array, # Array type with generic dtype support (Array[f64], etc.) @@ -285,24 +284,12 @@ def __getattr__(name: str): biased_depolarizing_noise = pecos_rslib.biased_depolarizing_noise general_noise = pecos_rslib.general_noise state_vector = pecos_rslib.state_vector +stabilizer = pecos_rslib.stabilizer sparse_stab = pecos_rslib.sparse_stab stab_vec = pecos_rslib.stab_vec density_matrix = pecos_rslib.density_matrix hugr_engine = pecos_rslib.hugr_engine -# Native QEC simulation/fault-catalog entry points. -# -# These are Rust-backed APIs from pecos-rslib-exp, re-exported here so common -# workflows can stay in the main `pecos` namespace: -# from pecos import sim_neo, stabilizer, depolarizing -depolarizing = pecos_rslib_exp.depolarizing -fault_catalog = pecos_rslib_exp.fault_catalog -meas_sampling = pecos_rslib_exp.meas_sampling -sim_neo = pecos_rslib_exp.sim_neo -stab_mps = pecos_rslib_exp.stab_mps -stabilizer = pecos_rslib_exp.stabilizer -statevec = pecos_rslib_exp.statevec - # Re-export noise model builder classes for direct instantiation GeneralNoiseModelBuilder = pecos_rslib.GeneralNoiseModelBuilder @@ -390,7 +377,6 @@ def __getattr__(name: str): "decoders", "delete", "density_matrix", - "depolarizing", "depolarizing_noise", "diag", "dtypes", @@ -399,7 +385,6 @@ def __getattr__(name: str): "exp", "f32", "f64", - "fault_catalog", "floor", "general_noise", "get_guppy_backends", @@ -421,7 +406,6 @@ def __getattr__(name: str): "math", "max", "mean", - "meas_sampling", "min", "nan", "newton", @@ -444,17 +428,14 @@ def __getattr__(name: str): "round", "selene_engine", "sim", - "sim_neo", "simulators", "sin", "sinh", "sparse_stab", "sqrt", - "stab_mps", "stab_vec", "stabilizer", "state_vector", - "statevec", "stats", "std", "sum", diff --git a/uv.lock b/uv.lock index 7511c093b..dac8bd4a5 100644 --- a/uv.lock +++ b/uv.lock @@ -3916,7 +3916,6 @@ dependencies = [ { name = "networkx", version = "3.4.2", source = { registry = "https://pypi.org/simple" }, marker = "python_full_version < '3.11'" }, { name = "networkx", version = "3.6.1", source = { registry = "https://pypi.org/simple" }, marker = "python_full_version >= '3.11'" }, { name = "pecos-rslib" }, - { name = "pecos-rslib-exp" }, { name = "pecos-rslib-llvm" }, { name = "phir" }, { name = "selene-sim" }, @@ -3953,7 +3952,6 @@ requires-dist = [ { name = "networkx", specifier = ">=2.1.0" }, { name = "pecos-rslib", editable = "python/pecos-rslib" }, { name = "pecos-rslib-cuda", marker = "extra == 'cuda'", editable = "python/pecos-rslib-cuda" }, - { name = "pecos-rslib-exp", editable = "python/pecos-rslib-exp" }, { name = "pecos-rslib-llvm", editable = "python/pecos-rslib-llvm" }, { name = "phir", specifier = ">=0.3.3" }, { name = "plotly", marker = "extra == 'visualization'", specifier = "~=5.9.0" }, From a1c51ace8ec2ebec671d51799910dea2806e918a Mon Sep 17 00:00:00 2001 From: Ciaran Ryan-Anderson Date: Tue, 12 May 2026 12:10:55 -0600 Subject: [PATCH 125/125] Fix test importing pecos-rslib-exp names from pecos namespace --- .../tests/qec/test_qec_ux_entrypoints.py | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/python/quantum-pecos/tests/qec/test_qec_ux_entrypoints.py b/python/quantum-pecos/tests/qec/test_qec_ux_entrypoints.py index f22efa311..aceeb3050 100644 --- a/python/quantum-pecos/tests/qec/test_qec_ux_entrypoints.py +++ b/python/quantum-pecos/tests/qec/test_qec_ux_entrypoints.py @@ -8,17 +8,24 @@ import pytest -def test_main_pecos_namespace_exports_sim_neo_stack() -> None: - from pecos import depolarizing, fault_catalog, meas_sampling, sim_neo, stabilizer +def test_sim_neo_stack_runs_from_exp() -> None: + pecos_rslib_exp = pytest.importorskip("pecos_rslib_exp") from pecos.quantum import TickCircuit tc = TickCircuit() tc.tick().mz([0]) - result = sim_neo(tc).quantum(stabilizer()).noise(depolarizing()).shots(2).seed(123).run() + result = ( + pecos_rslib_exp.sim_neo(tc) + .quantum(pecos_rslib_exp.stabilizer()) + .noise(pecos_rslib_exp.depolarizing()) + .shots(2) + .seed(123) + .run() + ) assert result.num_shots == 2 - assert meas_sampling() is not None - assert callable(fault_catalog) + assert pecos_rslib_exp.meas_sampling() is not None + assert callable(pecos_rslib_exp.fault_catalog) def test_build_memory_circuit_is_public_surface_helper() -> None: