wai-quantum 0.3.28: the dense state vector at any angle, the same bits threaded or not #147

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dcharlot merged 1 commit from wai-quantum-sv into main 2026-10-05 05:06:49 -04:00

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dcharlot commented 2026-10-04 17:02:01 -04:00

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Stacked on #145 → #144 → #143. Merge those in order first. Until then this diff also shows their commits.

What

wai-quantum 0.3.28 adds quantum_sv, the dense state vector at any angle. The byte-exact simulator is fixed-point and dyadic by design. This is the general state vector for everything else: arbitrary rotations, √W, fSim and random unitaries. It is also the ground truth that approximate methods are measured against, up to about 30 qubits.

• Layout. Real and imaginary parts are held in separate arrays. Qubit 0 is the most significant bit, matching the tensor networks.
• Kernels. Unrolled one- and two-qubit kernels, a general k-qubit kernel, and a diagonal fast path.
• Fusion around multi-qubit gates. One-qubit gates are absorbed into the multi-qubit gates on their qubits. Above width 2, adjacent multi-qubit gates also merge. Each move only crosses gates on other qubits, so the unitary is unchanged.
• Threads, with no unsafe code. Work is split into block-aligned slices. For gates on the top qubits, it is split at the top target bit instead, or into four quarters for adjacent pairs.
• One arithmetic per amplitude. Every kernel path computes each amplitude through the same row sum, in the same order. Threading therefore never changes a bit.
• Reductions (norm, Pauli expectations, sorted-uniform sampling) are summed in fixed chunks.
• gates. The Gate type moves here from quantum_tn and is re-exported there. It comes with the standard gates by name: H, X, Y, Z, S, T, √X/√Y/√W, RX/RY/RZ, phase, CX, CZ, SWAP, iSWAP, CPhase, RZZ and fSim.
• CLI. wai-quantum sv --file CIRCUIT.jsonl [--fuse W] [--top K | --sample S | --expect "Z0 Z1; X3"] [--json]. tn now shares its circuit reader.

Evidence

Against an independent simulator. Final states of random circuits agree to 2·10⁻¹⁶ at fusion widths 0, 2 and 4. The circuits are phased-XZ rotations, fSim gates and partial iSWAPs on 8, 12 and 16 qubits.

Two methods in one crate. Tensor-network amplitudes equal the state vector's to 10⁻¹² on 18 qubits (tests/tn_vs_sv.rs). This covers five bitstrings and an open-output batch, contracted with sliced plans.

Speed. A 26-qubit, depth-20 circuit of 770 gates runs in about 9 s at fusion width 2, in double precision, on one machine. Unfused it takes 15.5 s. Before the split-path threading and fusion around multi-qubit gates it took 78–124 s.

A determinism bug caught and closed. The first native-vs-WASI pin disagreed:

• Cause. A threaded path for gates on the top qubits summed matrix rows in a different order from the block kernel that a single thread (or WASI) uses.
• Fix. Every multi-qubit kernel now goes through one shared row sum.
• Guard. A native test forces 1, 2, 3, 8 and 32 threads at fusion widths 0–4 and demands identical states and reductions. CI runs the pins natively only, so this is the guard CI can see. Reversing one kernel's sum makes that test fail, and only that test.

Tests

• Every kernel path matches an independent gate-by-gate reference, including at 16 qubits, where the split paths run.
• Named-gate identities hold: √X² = X, √Y² = Y, √W² = W, T² = S, S² = Z.
• Bell-state expectations, sampling balance and expectation values are checked against direct sums.

Pins and suite

• bit_identity pins a 16-qubit run at widths 0, 2 and 3 that exercises every path. All 13 pins pass natively and under wasm32-wasip2.
• sv and tn output is byte-identical natively and as a WASI component.
• cargo test --locked --features full --lib --tests (debug): 377 + 13 + 2 + 1 + 3 passed.
• Every feature builds alone with zero warnings, and clippy is clean on the new code.

🤖 Generated with Claude Code

**Stacked on #145 → #144 → #143.** Merge those in order first. Until then this diff also shows their commits. ## What `wai-quantum` 0.3.28 adds **`quantum_sv`, the dense state vector at any angle**. The byte-exact simulator is fixed-point and dyadic by design. This is the general state vector for everything else: arbitrary rotations, √W, fSim and random unitaries. It is also the ground truth that approximate methods are measured against, up to about 30 qubits. - **Layout.** Real and imaginary parts are held in separate arrays. Qubit 0 is the most significant bit, matching the tensor networks. - **Kernels.** Unrolled one- and two-qubit kernels, a general k-qubit kernel, and a diagonal fast path. - **Fusion around multi-qubit gates.** One-qubit gates are absorbed into the multi-qubit gates on their qubits. Above width 2, adjacent multi-qubit gates also merge. Each move only crosses gates on other qubits, so the unitary is unchanged. - **Threads, with no unsafe code.** Work is split into block-aligned slices. For gates on the top qubits, it is split at the top target bit instead, or into four quarters for adjacent pairs. - **One arithmetic per amplitude.** Every kernel path computes each amplitude through the same row sum, in the same order. Threading therefore never changes a bit. - **Reductions** (norm, Pauli expectations, sorted-uniform sampling) are summed in fixed chunks. - **`gates`.** The `Gate` type moves here from `quantum_tn` and is re-exported there. It comes with the standard gates by name: H, X, Y, Z, S, T, √X/√Y/√W, RX/RY/RZ, phase, CX, CZ, SWAP, iSWAP, CPhase, RZZ and fSim. - **CLI.** `wai-quantum sv --file CIRCUIT.jsonl [--fuse W] [--top K | --sample S | --expect "Z0 Z1; X3"] [--json]`. `tn` now shares its circuit reader. ## Evidence **Against an independent simulator.** Final states of random circuits agree to **2·10⁻¹⁶** at fusion widths 0, 2 and 4. The circuits are phased-XZ rotations, fSim gates and partial iSWAPs on 8, 12 and 16 qubits. **Two methods in one crate.** Tensor-network amplitudes equal the state vector's to 10⁻¹² on 18 qubits (`tests/tn_vs_sv.rs`). This covers five bitstrings and an open-output batch, contracted with sliced plans. **Speed.** A 26-qubit, depth-20 circuit of 770 gates runs in about 9 s at fusion width 2, in double precision, on one machine. Unfused it takes 15.5 s. Before the split-path threading and fusion around multi-qubit gates it took 78–124 s. **A determinism bug caught and closed.** The first native-vs-WASI pin disagreed: - **Cause.** A threaded path for gates on the top qubits summed matrix rows in a different order from the block kernel that a single thread (or WASI) uses. - **Fix.** Every multi-qubit kernel now goes through one shared row sum. - **Guard.** A native test forces 1, 2, 3, 8 and 32 threads at fusion widths 0–4 and demands identical states and reductions. CI runs the pins natively only, so this is the guard CI can see. Reversing one kernel's sum makes that test fail, and only that test. **Tests** - Every kernel path matches an independent gate-by-gate reference, including at 16 qubits, where the split paths run. - Named-gate identities hold: √X² = X, √Y² = Y, √W² = W, T² = S, S² = Z. - Bell-state expectations, sampling balance and expectation values are checked against direct sums. **Pins and suite** - `bit_identity` pins a 16-qubit run at widths 0, 2 and 3 that exercises every path. All 13 pins pass natively and under `wasm32-wasip2`. - `sv` and `tn` output is byte-identical natively and as a WASI component. - `cargo test --locked --features full --lib --tests` (debug): 377 + 13 + 2 + 1 + 3 passed. - Every feature builds alone with zero warnings, and clippy is clean on the new code. 🤖 Generated with [Claude Code](https://claude.com/claude-code)

dcharlot added 4 commits 2026-10-04 17:02:01 -04:00

wai-quantum 0.3.25: error correction at circuit level, sampled, modelled and decoded exactly ... ed592d76f9

quantum_frame takes an error-correction experiment as what it is: a noisy
Clifford circuit with detectors and observables.

- parse reads the ecosystem's circuit text (resets and measurements in Z and
  X, H/S/sqrt(X)/Paulis/CX/CZ/SWAP, flip and depolarizing noise, detectors,
  observables, REPEAT), and refuses anything else rather than skipping it.
- sample is bit-packed Pauli-frame simulation, 64 shots per word, with
  geometric skipping between noise hits; reproducible from
  (circuit, shots, seed).
- error_model derives the detector error model by backward sensitivity
  propagation. It converts depolarizing channels to equivalent independent
  mechanisms exactly, XOR-merges identical ones, and refuses non-deterministic
  detectors. A graphlike mechanism stays one matching edge; otherwise it splits
  into X and Z halves, then into per-qubit parts.
- surface_code_memory generates the rotated surface-code memory experiment.

quantum_match decodes by exact minimum-weight perfect matching: Dijkstra on
integer weights, with boundary paths computed once and dominated pairs cut,
then Edmonds' blossom. memory_experiment and fit_code_model measure
P(d) = a(p/p*)^((d+1)/2): a = 0.023, p* = 0.0100 under uniform circuit
noise, and CodeFit::surface_code feeds that into a resource estimate.

Checked against an independent implementation:
- generated circuits identical byte for byte (135 configurations, d 2-15,
  1-8 rounds);
- error models identical mechanism for mechanism, to 1e-12 in probability
  (41 circuits: rotated and unrotated surface codes in both bases,
  repetition codes);
- decoded logical error rates within 1.4 standard errors on all 12 grid
  points.

tests/frame_reference.rs keeps a circuit and a model from that implementation
as fixtures. Blossom equals brute force on 3000 random graphs. A mirrored
random Clifford circuit over every gate type ties the sampler's forward rules
to the model's backward ones. Mutating the depolarizing conversion, any gate
rule on either side, the determinism check or the decomposition fails a named
test. bit_identity pins sampling, decoding and the fit natively and under
wasm32-wasip2; repro gains an in-crate exp, within an ulp.

CLI: wai-quantum qec [-d --rounds --p --shots --seed --json] | --file |
--circuit | --dem | --fit, and estimate --prefactor/--threshold for a
measured code. Byte-identical natively and under wasm32-wasip2.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

wai-quantum 0.3.26: tensor-network contraction, hyper-optimised, sliced, bit-identical ... ae0d1c4cd4

quantum_tn turns a circuit (any unitary on any qubits, as a matrix) into the
tensor network of one amplitude or an open-output batch, and contracts it.

- Network::amplitude builds the network; simplify absorbs vectors and
  one-qubit gates into neighbours.
- find_path is a seeded hyper-optimiser over two tree families:
  - randomised greedy, scoring size(out)/c - c(size(a)+size(b)) with Gumbel
    noise;
  - recursive bipartition, multilevel (heavy-edge coarsening, several
    initial cuts, refinement at every level), with greedy leaves.
  Families alternate until one leads; later trials sample near the best
  parameters. The best few trees are reconfigured: subtrees of up to eight
  tensors are re-contracted optimally by subset dynamic programming, until
  nothing improves.
- slice fixes the index that leaves the least total work until the largest
  intermediate fits the cap, pricing each candidate incrementally. A second
  search round then finds a tree for the network with the first round's
  slices fixed (all, or the more valuable half).
- contract_plan contracts every slice in a fixed accumulation order and sums
  them in order. Threads are bounded by an 8 GiB budget; WASI runs
  sequentially. The bits are the same everywhere.

Measured on single amplitudes of random circuits on the 54-qubit
advantage-experiment grid (fSim(pi/2, pi/6), staggered couplers), 256 trials,
under ten seconds each, in log10 operations:
  m = 10: 10.48   m = 12: 13.91   m = 14: 14.63   m = 16: 17.60   m = 20: 18.77
An independently developed hyper-optimiser, given the identical networks,
lands within 0.4 of these at every depth, in either direction. The 54-qubit,
10-cycle amplitude, contracted here in 16 slices, agrees with an independent
contraction to 12 significant figures.

Tests:
- Amplitudes match a dense state vector for every tree family, with
  reconfiguration and with slicing.
- Reconfiguration reaches the exact optimum on 40 random small networks.
- Incremental slice pricing matches a full recount.
- The same seed gives the same plan.
- Mutating the permutation, the complex product, the contraction's summed
  indices, slice pricing, the slice offset or the reconfiguration DP fails a
  named test.
- bit_identity pins a plan and its sliced, threaded amplitude natively and
  under wasm32-wasip2.

CLI: wai-quantum tn --file CIRCUIT.jsonl [--bits --open --trials --seed
--cap-log2 --plan-only --json], byte-identical natively and under
wasm32-wasip2.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

wai-quantum 0.3.27: Gaussian boson sampling, exactly ... 6ab907e107

A photonic sampler's outcome probabilities are hafnians (photon-number
detection) or torontonians (threshold detection) of its Gaussian state.
quantum_gbs computes both exactly and reproducibly.

- hafnian: power traces, a sum over 2^{n/2} pair subsets, each the
  lambda^{n/2} coefficient of exp(sum tr(B^k) lambda^k / 2k). The traces come
  from a Householder Hessenberg reduction, La Budde's characteristic
  polynomial and Newton's identities: O(n^3 2^{n/2}).
- torontonian: inclusion-exclusion over the 2^m clicked-mode subsets.
- Both sums run in 64 fixed chunks, threaded natively and sequential on WASI,
  added in chunk order, so the bits do not depend on threading.
- GaussianState: squeezed vacua through an interferometer with uniform loss,
  as the complex covariance in the (a, a-dagger) basis.
- click_probability, photon_probability: exact pattern probabilities.
- sample_clicks: exact samples, drawn mode by mode from marginal
  torontonians.
- click_marginals, check_samples: the one- and two-mode click statistics
  every sampler of the state must reproduce, polynomial in the modes, and a
  z-score check of observed patterns against them.

Against an independent implementation:
- click probabilities of three lossy states, every pattern: 1.1e-10;
- photon probabilities up to four photons: 2.3e-13;
- hafnians: 1.5e-12 up to 20x20 and 4.5e-8 at 36x36, where the alternating
  sum loses precision on either side. A 36x36 hafnian takes under 2 s.

Tests:
- hafnians match exhaustion over matchings, and (2k-1)!!;
- squeezed vacuum reproduces its textbook click and photon statistics;
- click probabilities sum to one with loss;
- exact samples reproduce marginals and full-pattern frequencies, and pass
  the check, while a different interferometer fails it.
Mutating the hafnian sign, La Budde's recurrence, Newton's identities, the
torontonian sign or the loss channel fails a named test. bit_identity pins a
24x24 hafnian and a 14-click torontonian (threaded natively, sequential under
WASI), probabilities, samples and marginals, on both targets.

CLI: wai-quantum gbs --squeezing ... [--eta --seed | --unitary] [--sample K |
--check FILE] [--json], byte-identical natively and under wasm32-wasip2.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

wai-quantum 0.3.28: the dense state vector at any angle, the same bits threaded or not ... 38a205ee33

The byte-exact simulator is fixed-point and dyadic by design. quantum_sv is
the general state vector for everything else (arbitrary rotations, sqrt W,
fSim, random unitaries), and the ground truth approximate methods are
measured against, up to about 30 qubits.

- Split real and imaginary arrays; qubit 0 most significant, as in the
  tensor networks.
- Kernels: unrolled one- and two-qubit, general k-qubit, and a diagonal
  fast path.
- Fusion around multi-qubit gates: pending one-qubit gates join the next
  multi-qubit gate on their qubit, trailing ones the last, and above width 2
  adjacent multi-qubit gates merge. Each move only crosses gates on other
  qubits.
- Threads, with no unsafe code: block-aligned slices, and for gates on the
  top qubits a split at the top target bit, or into four quarters for
  adjacent pairs.
- Every path computes each amplitude through one row sum in one order, so
  threading never changes a bit. The native-vs-WASI pin caught a path whose
  sum ran in a different order; the fix is the shared row_dot, and a test
  now forces 1/2/3/8/32 threads and demands identical states (falsified by
  reversing one kernel's sum).
- Reductions (norm, Pauli expectations, sorted-uniform sampling) are summed
  in fixed chunks.

gates: Gate moves here from quantum_tn (re-exported there), with the
standard gates by name: H, X, Y, Z, S, T, sqrt X/Y/W, RX/RY/RZ, phase, CX,
CZ, SWAP, iSWAP, CPhase, RZZ, fSim.

Checked:
- final states of random circuits on 8, 12 and 16 qubits agree with an
  independent simulator to 2e-16 at fusion widths 0, 2 and 4;
- tensor-network amplitudes equal the state vector's to 1e-12 on 18 qubits
  (tests/tn_vs_sv.rs);
- a 26-qubit, depth-20, 770-gate circuit runs in about 9 s at width 2, in
  double precision.

CLI: wai-quantum sv --file CIRCUIT.jsonl [--fuse --top --sample --expect
--json]; tn shares its circuit reader. Byte-identical natively and under
wasm32-wasip2.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

dcharlot referenced this pull request 2026-10-04 17:34:08 -04:00

wai-quantum 0.3.29: the architecture around the code, priced, and the 2025 factoring machine re-run #148

dcharlot referenced this pull request 2026-10-04 21:30:58 -04:00

wai-quantum 0.3.30: qLDPC memory at circuit level, re-derived from the circuit up #150

dcharlot merged commit 04be3315af into main 2026-10-05 05:06:49 -04:00

dcharlot referenced this pull request from a commit 2026-10-05 05:06:51 -04:00

Merge pull request 'wai-quantum 0.3.28: the dense state vector at any angle, the same bits threaded or not' (#147) from wai-quantum-sv into main

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