wai-quantum 0.3.40: rectangle space groups, a sector referee on its own basis, and a sector larger than the network #194

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dcharlot merged 3 commits from wai-quantum-nqs-rectangle into main 2026-10-09 03:48:28 -04:00

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2026-10-08

Transaction Science

wai-quantum 0.3.40: a sector larger than the network, held to its exact answer ...

On the periodic 6 × 4 J1-J2 lattice at J2 = J1/2 the orbit referee
places the ground state (−12.54059845, equal to the full 24-spin
diagonalisation) in the sector even under the half turn and both
reflections at momentum zero, with even parity: 15 578 configurations
up to symmetry, against a complex α = 1 network's 624 parameters.
After 600 steps, energies over every configuration: translations
guided 1.06e-3; rectangle group unguided 8.32e-3; rectangle group
guided 5.57e-4.

On the 6 × 6 open Heisenberg lattice (unprojected, α = 2, 800 steps)
the guide doubled the error, so unprojected networks keep sampling
|ψ|²; the docs say so.

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

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2026-10-08 19:47:12 -04:00

Transaction Science

nqs_ground: a projected network up to 24 spins is held to its sector alone ...

The full reference was computed first and then replaced by the
sector's; past 20 spins that first step was a DMRG run (136 s on the
6 × 4 torus, and 3 % off the exact energy) whose answer was thrown
away.

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

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2026-10-08 14:17:42 -04:00

Transaction Science

wai-quantum: rectangle space groups, and the sector referee on the sector's own basis ...

Symmetry::rectangle projects onto the translations of an lx × ly torus
with its half turn and axis reflections, in one of their four
one-dimensional representations (RectIrrep), at momentum 0 or π along
each direction.

SpinModel::exact_ground_energy_in now works on one state per orbit of
the group, Σ_g χ(g)|g·r⟩ normalised for each least configuration r
that no element of character −1 fixes, up to 24 spins. The projector
referee it replaces is kept in the tests, and the two agree to 1e-9 in
all 24 sectors of the 4 × 3 J1-J2 torus, on a 10-site ring, and on an
Ising ring in a transverse field. The identity alone gives the plain
diagonalisation; the flip alone splits it in two.

The CLI and nqs_ground take --reflections a1|a2|b1|b2, and hold a
projected network to its sector up to 24 spins.

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

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2026-10-08 13:12:32 -04:00