Round 2 verification audit for C034

Model: gpt-5

Claim: The unitary gate based on the same Hamiltonian H_A produces (|down,down> - i|ee>)/sqrt(2) with a fidelity >~ 99% [Mehta2020].

Source alignment: source/main.tex:155-155 (Experimental error analysis)

Prior official verdict: verified with failure_reason None.

Executable evidence: none. Sandbox rerun logs: none.

Independent audit: I read the citation audit and local extracted citation text. The evidence is full-text citation support rather than a computation; the cited source statements support the platform/result attribution in the claim.

Decision: Round 2 verdict is verified with failure_reason None and limitations []. Notes: Mehta2020 = 'Integrated optical multi-ion quantum logic' (arXiv:2002.02258, Nature 586, 533), companion paper from the same group, fetched full text. It reports a unitary Molmer-Sorensen (sigma_x sigma_x) entangling gate that ideally produces exactly (1/sqrt(2))(|down,down> - i|up,up>) = (|dd> - i|ee>)/sqrt(2) starting from |down,down>, with measured Bell-state fidelity 99.3(2)% (parity-oscillation contrast 99.2(2)%, gate-time populations 99.4(1)%). Paper claim: same H_A-type unitary gate produces (|dd> - i|ee>)/sqrt(2) with fidelity >~99%. State form, gate Hamiltonian type, and fidelity (99.3% >= 99%) all match. Conclusion: verified.