open-standards/wai/wai-quantum/README.md

wai-quantum

A deterministic quantum stack in pure Rust. Byte-exact circuit simulation, the operational layer around it, and signed energy-accounted receipts binding every stage.

No QPU, no cloud service, no vendor SDK, and no system libraries — so the same source runs natively, in the browser via wasm, and as a WASI component at the edge, producing byte-identical results and receipts on all three.

[dependencies]
wai-quantum = "0.3"

use wai_quantum::quantum::Circuit;
use wai_quantum::quantum_toolchain as qt;

let mut c = Circuit::new(3);
c.h(0).cx(0, 1).cx(1, 2);              // GHZ
let sv = c.simulate().unwrap();
println!("{:?}", qt::top_outcomes(&sv, 2));   // |000> 0.5, |111> 0.5
// a portable identity for the reconstruction — same on every machine
let h: [u8; 32] = sv.statevector_hash();

What's in it

Feature	What it gives you

Cross-architecture reproducibility is tested, not asserted. The full test suite passes under wasm32-wasip2 on wasmtime as well as natively, and the floating-point results — entropy, the Holevo bound — are pinned to their exact IEEE-754 bits, so a platform that computes something different fails the suite instead of quietly returning a different number:

CARGO_TARGET_WASM32_WASIP2_RUNNER=wasmtime cargo test --release --target wasm32-wasip2 --features full

The same binary answers what a state carries, not only what a circuit does:

wai-quantum entropy bell --keep 0    # half a Bell pair: 1 bit, invisible to a state vector
wai-quantum channel depolarizing --prob 0.5
wai-quantum bb84 --eavesdrop         # interception shows up in the error rate
wai-quantum chsh                     # 2 sqrt(2), exactly, not sampled
wai-quantum qutrit                   # d = 3, not just qubits

channel prints the Holevo bound before and after, and it can only fall: noise never creates information.

| quantum | byte-exact statevector simulation (dyadic Clifford+T+P(k)) | | quantum_toolchain | algorithm library, backend recommendation, OpenQASM 2/3 ingest of what the mainstream toolchains actually export — both register and both measurement spellings, rx/ry/rz/sx/u/u2/u3/crz, and exact rational-multiple-of-pi angles (non-dyadic angles are refused, never rounded) — Bloch / entanglement / purity analysis | | quantum_stabilizer | stabilizer (CHP) tableau — O(n²), scales far past statevector | | quantum_mps | tensor-network (matrix-product-state) backend | | quantum_pauli | sparse-Pauli / Heisenberg observable propagation | | quantum_receipt | signed, energy-accounted receipt over a reconstruction | | quantum_ops | the operations/attestation layer | | quantum_cal, quantum_control, quantum_noise | calibration, filter-function robust control, DD noise spectroscopy, Cycle-Benchmarking noise learning | | quantum_mitigate | zero-noise extrapolation, readout M3, classical shadows | | quantum_qec | CSS codes (distance verified by exhaustive search, not asserted) — rotated surface [[d²,1,d]], toric, bivariate-bicycle, and the [[7,1,3]] colour code, whose self-duality buys a transversal logical Hadamard — one round, no ancillas, no surgery — verified on the simulator, with the surface code shown failing the same move — with two decoders: union-find (weighted matching, single-shot, space-time with faulty measurement, and circuit-level with hook errors; imports and exports Stim-syntax detector error models, so other tools' noise models decode here and ours decode there) and Relay-BP (for qLDPC) | | quantum_compile | Clifford routing + stabilizer-tableau equivalence proof | | quantum_atom | neutral-atom register preparation (Hungarian / LSAP) | | quantum_qir | QIR export + ingest — emit and parse QIR (the QIR Alliance's LLVM-based IR); emitted modules validated with llvm-as, and 9 of 10 catalog algorithms re-ingest to a bit-identical statevector | | quantum_comm | key distribution and security: BB84 with an intercept-resend eavesdropper (a quiet channel gives a perfect key; interception costs a quarter of it), and the no-cloning theorem priced | | quantum_qudit | qubits and qutrits: the Weyl–Heisenberg group, the Fourier gate over Z_d, the controlled sum — exact for d = 2 and 3 | | quantum_info | mixed states: density matrices, the partial trace, purity, exact Pauli expectations, and CHSH against the classical and Tsirelson bounds | | quantum_source | the limits on encoding and transport: von Neumann entropy, the Schumacher limit, and the Holevo bound — which says n qubits carry at most n classical bits, so quantum does not compress classical media | | quantum_channel | transport itself: Kraus channels (bit flip, dephasing, depolarizing, amplitude damping), and linear-inversion tomography to see what actually arrived — with the law that a channel can only lose information, never create it | | quantum_qbom | Quantum Bill of Materials — stage receipts into one manifest | | quantum_vml, quantum_phasor, quantum_qfhrr, quantum_kernel, quantum_qdata, quantum_phasor_meter | the interference / phasor ML layer | | full | everything |

Default features are quantum, quantum_toolchain, quantum_receipt.

Speed

Byte-exactness is the contract, so the simulator is optimised only in ways that cannot move a single amplitude: identity does nothing, a diagonal gate phases half the state with one multiply rather than four, and X — so CX — is a swap with no arithmetic at all. fxmul(ONE, x) == x exactly in this fixed point, which is what makes those paths provably identical rather than merely close, and they are checked against the previous implementation amplitude by amplitude.

An all-real matrix — H, and any real rotation — halves its multiplies too, since the imaginary cross terms are multiplications by exactly zero.

At 20 qubits that is 8.9x on Z, 7.1x on X, 4.6x on CZ, 4.3x on CX, 3.4x on T, 1.9x on Y and 1.8x on H.

Determinism

Simulation is byte-exact: amplitudes are dyadic fixed-point, so a circuit reconstructs to the same statevector_hash on every machine and every target. The approximate methods (MPS truncation, the phasor/ML layer) are reproducible f64 — IEEE-754-strict, identical given the same inputs and seed — and are documented as such rather than claimed byte-exact.

A receipt separates the two halves of a cost honestly: work is portable-exact (n_ops · 2^n amplitude updates, recomputed by the verifier, so a sink cannot inflate it) and energy is measured-attested (only the signer can vouch for its own silicon). Signatures travel between substrates because the computation is reproducible — not because two runtimes agreed to trust each other.

Also available

• A CLI (wai-quantum in the wai crate) — run circuits, emit OpenQASM, seal and verify receipts, native or under wasmtime.
• A WASI-HTTP component serving the stack as an ordinary HTTP handler.
• Browser demos and a course: https://wai.transaction.science/quantum-ide

License

Apache-2.0