wai-quantum 0.6.6: Clifford circuits measured in a product basis, exactly, by cut-rank #340

Merged

dcharlot merged 5 commits from wai/quantum-cutrank-0.6.6 into main 2026-10-19 20:26:27 -04:00

Conversation 0 Commits 5 Files changed 18 +1662 -11

2026-10-19

Transaction Science

wai-quantum cutrank: clippy's is_multiple_of and an enumerated loop ...

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

c1c325002f

• View at this point in history

2026-10-19 11:29:49 -04:00

Transaction Science

wai-quantum 0.6.6: the cut-rank engine in the README and changelog ...

A feature row and a section for quantum_cutrank; the changelog entry; the
version in every lockfile that pins it.

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

f599f0a6fc

• View at this point in history

2026-10-19 11:23:35 -04:00

Transaction Science

wai-quantum examples: patched cross-entropy benchmarking from shots (patch_xeb) and one amplitude's contraction cost (tn_cost) ...

patch_xeb simulates each patch of a patched circuit exactly on the dense
state vector and scores the measured shots (normalised linear XEB per
patch, the product, its error). On a published 61-qubit experiment's
release it reproduces the released per-circuit fidelities to 5e-7 (their
JSON's rounding). tn_cost prints log10 of one amplitude's contraction cost
as find_path sees it, with the largest intermediate and the slices.

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

bdd46363b5

• View at this point in history

2026-10-19 11:21:04 -04:00

Transaction Science

wai-quantum cutrank: the steps planned once, tables stored at a chosen precision, and orders annealed for less work ...

- The table operations (coordinate swaps, kernel merges, doublings, XOR
  sums, the sign masks) depend on the graph and the order alone, so they
  are planned once per state; an amplitude or a sample only runs passes.
- Precision::Single stores the table in f32 (arithmetic stays f64): half
  the memory and traffic, amplitudes within 1e-5 of the double ones (test).
- A merge followed by a doubling is one pass; a doubling no longer
  zero-fills. Every pass is cut into fixed chunks, so reductions do not
  depend on the threads.
- work() = Σ 2^cut, passes() tallies the passes by kind, and
  anneal_order(moves, seed) searches orders by simulated annealing, never
  returning a worse one (test: lower work, same amplitudes).

On the tracker's 70-qubit random graph-state instance (build host):
natural order, max cut 32: amplitude 6.2 s (f64) / 4.7 s (f32), sample
7.5 s (f32). Annealed order (seed 3, 20 000 moves): max cut 29, work 6.5×
less, largest table 4 GiB in f32: amplitude 0.53 s, exact sample 1.49 s,
amplitudes agreeing with the natural order's double ones to 1e-7.

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

70af6b4dcd

• View at this point in history

2026-10-19 11:21:04 -04:00

Transaction Science

wai-quantum: exact amplitudes and samples of a Clifford circuit measured in a product basis, by cut-rank elimination ...

Tableau::graph_form writes the state as local Cliffords on a graph state.
quantum_cutrank (feature quantum_cutrank, in full) then sums
⟨x|⊗V_q|ψ⟩ = 2^{-n/2} Σ_z ∏ W_q[x_q][z_q] (−1)^{Σ_{a~b} z_a z_b} one qubit at a
time along an order, in a table of 2^{cut-rank} entries: each qubit is an
in-place pass (a merge where the boundary space loses a dimension, the
qubit's signed terms, a doubling or an XOR-shifted sum for its edges
ahead). By Parseval the table's norm is the prefix probability, so the same
passes sample exactly. Reductions are summed in fixed chunks.

Tests: the graph form rebuilds the state (40 random circuits); amplitudes
equal the state vector's in probability and relative phase (30 circuits up
to 12 qubits); forward, reverse and shuffled orders agree (24–54 qubits, at
least 30 comparisons); samples follow the exact law (60k shots) and are
seeded; cut-ranks of GHZ and product states. Mutants caught: merge signs,
the sampling choice, the graph form without its S, the doubling's sign.

examples/cutrank_qasm reads an OpenQASM 2 Clifford bulk with a closing
single-qubit layer. On the tracker's 70-qubit random graph-state instance
(max cut 32 bits, matching an independent tableau): an exact amplitude in
about 7.6 s and an exact sample in about 14 s on the build host, 69 GB peak
in f64.

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

bf22681fae

• View at this point in history

2026-10-19 11:21:04 -04:00