wai-quantum 0.6.7: tensor networks that split controlled gates and fix projections #343

Merged

dcharlot merged 3 commits from wai/quantum-tn-split-0.6.7 into main 2026-10-19 22:37:45 -04:00

Conversation 0 Commits 3 Files changed 16 +365 -20

2026-10-19

Transaction Science

wai-quantum 0.6.7: the changelog entry, and the version in every lockfile that pins it ...

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

50c6f8ec95

• View at this point in history

2026-10-19 20:29:45 -04:00

Transaction Science

wai-quantum tn: Network::reduce fixes the indices a tensor allows one value of ...

Where a tensor is zero unless index i takes v, every tensor holding i keeps
its entries at v and drops i, repeated until nothing changes; then simplify.
Only zeros are read and entries selected. Projections run through diagonal
gates and the deltas of split ones, so a CZ beside a projected output becomes
scalars. Open indices are never fixed. simplify itself is unchanged, so
networks that do not call reduce keep their bits.

On the same 61-qubit CZ circuits (depth 8/12/16/20, 64 trials): log10
multiply-adds 5.35/8.25/11.22/14.26 split and reduced, against 6.58/9.23/
12.09/15.16 split alone and 8.03/12.46/16.09/19.64 whole and simplified.

tn_cost, the CLI's tn subcommand and the service's tensor_network method
reduce their split networks. Tests: split networks reduced, and whole-gate
networks reduced, give the state vector's amplitudes; open outputs too.

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

382cf672a2

• View at this point in history

2026-10-19 20:29:22 -04:00

Transaction Science

wai-quantum tn: split controlled and diagonal gates at their block-diagonal qubits ...

Network::amplitude_split builds the same network as Network::amplitude but
splits each gate on two or more qubits at every qubit it is block-diagonal on
(a control, or a qubit it is diagonal on): G = Σ_a |a⟩⟨a| ⊗ G_a becomes the
delta δ(out, in, k) on that qubit's wire and the blocks G_k, joined by a bond
of dimension 2. Only zeros of the matrix are read, so the amplitudes are the
same entries' sums. A cut through a CZ or CX then costs 2, not 4.

On the 61-qubit CZ circuits of a published release, depth 8/12/16/20, the
search (64 trials) finds log10 multiply-adds 6.58/9.23/12.09/15.16 on split
networks against 8.03/12.46/16.09/19.64 on whole-gate ones. 1024 trials do not
lower them further.

tn_cost, the wai-quantum CLI's tn subcommand (--whole-gates for the old
networks) and the service's tensor_network method build split networks.

Tests: split networks give the state vector's amplitudes on circuits of CZ,
CX both ways, a controlled random unitary, random diagonal gates, Toffoli,
CCZ and random two-qubit unitaries, with outputs projected and open; CZ and
CX split and a random unitary does not, CX at its control; on a 4 × 5 CZ grid
of 12 layers the split network's tree costs less than an eighth of the
whole-gate one's.

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

36b1137a23

• View at this point in history

2026-10-19 20:29:22 -04:00