Round 2 verification audit for C066

Model: gpt-5

Claim: The states |down,up> and |up,down> acquire a relative phase phi = 2 epsilon Delta t, so a system initially in |Psi^-> is found in |Psi^+> after one drive-(A) cycle (t = 2 x 2 pi/delta) with probability p = sin^2(phi/2) ~= 0.5.

Source alignment: source/supp_content.tex:125-125 (Supp. Mat. S4)

Prior official verdict: partial with failure_reason mismatch.

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

Independent audit: I inspected the symbolic and numeric script against supp_content.tex:125. The symbolic mapping P(Psi+)=sin^2(phi/2) is correct. Plugging the paper-stated eps=0.05, Delta=2pi25 kHz, and t=2(2pi/delta) gives p=0.768, not the printed approx 0.5. The qualitative large-error claim holds, but the numeric estimate is not reproduced; partial/mismatch remains.

Decision: Round 2 verdict is partial with failure_reason mismatch and limitations ['paper_text_only_reimplementation']. Notes: Structural relations CONFIRMED: phi = 2 eps Delta t is the correct differential relative phase, and P(|Psi+>) = sin^2(phi/2) is verified symbolically (sympy). NUMERIC mismatch: with eps=0.05, Delta=2pi x 25 kHz, delta=2pi x 14.7 kHz, t=2*(2pi/delta)=136.05 us, phi=2.137 rad and p=sin^2(phi/2)=0.768. Paper states p ~= 0.5; recomputed p ~= 0.77 (abs diff 0.27 vs 0.5). The ~0.5 is a rough order-of-magnitude 'large per-cycle error' statement; the qualitative conclusion (near order-unity error destroying the protocol) holds for either value. -> partial / mismatch.