Round 2 verification audit for C063

Model: gpt-5

Claim: For a drive (C) Rabi-frequency imbalance Omega_C^{(2)} = Omega_C^{(1)}(1+epsilon) with theta=3 pi/4, the singlet is repumped with probability p ~= 1.4 epsilon^2 per cycle, so p<<1e-4 requires epsilon<<1e-2.

Source alignment: source/supp_content.tex:121-121 (Supp. Mat. S3)

Prior official verdict: verified with failure_reason None.

Executable evidence: run.py. Sandbox rerun logs: run.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: Simulate a single cycle with an imbalanced drive (C) at theta=3 pi/4 and fit the per-cycle singlet-loss probability to 1.4 epsilon^2; check the 1e-4/1e-2 threshold.. 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: Paper: drive-C imbalance Omega_C^(2)=Omega_C^(1)(1+eps), theta=3pi/4 -> singlet repumped with p~1.4 eps^2/cycle; p<<1e-4 needs eps<<1e-2. Simulation (U_C -> per-ion rotations theta and theta(1+eps), one cycle S_C_imb S_B S_A applied to |Psi->): per-cycle singlet loss is purely quadratic, p/eps^2=1.388 over eps in [0.002,0.05], LSQ fit c=1.386 vs paper 1.4 (~1%). Threshold p<<1e-4 -> eps<<8.5e-3, consistent with eps<<1e-2. Clean match -> verified.