Round 2 verification audit for C005

Model: gpt-5

Claim: Drive (C) is described by the unitary U_C(theta) = exp(i (theta/2) sigma_x) tensor exp(i (theta/2) sigma_x), with sigma_x = |up><up|.

Source alignment: source/main.tex:107-108 (Dissipation scheme)

Prior official verdict: verified with failure_reason None.

Executable evidence: sympy_check.py. Sandbox rerun logs: sympy_check.log.

Independent audit: I scanned the copied script for imports/shared helper dependencies and reran it through the sandbox. The code is self-contained in this attempt directory and targets the claim strategy: Verify U_C is a symmetric (collective) rotation that cycles population within the triplet subspace while leaving |Psi^-> invariant.. I checked the relevant family model rather than relying only on exit status; the rerun is treated as one reproducibility input.

Decision: Round 2 verdict is verified with failure_reason None and limitations []. Notes: U_C(theta)=exp(i theta S_x) collective rotation. For theta in {0,0.2,0.5,0.716,1.0}pi: U_C|Psi->=|Psi-> (overlap 1.0, no phase) and triplet subspace invariant; U_C(0.5pi) cycles triplet population (|dd> changes). Matches ground truth (U_C leaves singlet invariant). -> verified.