C042 - The state after N cycles is rho_N = [S(Phi,gamma,theta)]^N rho_0 in vectorized form, and...
Verdict: verified
Location: Supp. Mat. S1, Eq. (S2)
Type / expected artifact: math / math
Claim: The state after N cycles is rho_N = [S(Phi,gamma,theta)]^N rho_0 in vectorized form, and the fidelity follows F(N) ~= 1 - C_0 lambda_max^N = 1 - C_0 e^{-N/N_0}, where lambda_max is the second-largest eigenvalue and 1/N_0 the convergence rate.
Models: extraction claude-opus-4-8; verification gpt-5; verification_chain claude-opus-4-8 -> gpt-5; verdict_chain verified -> verified.
Source location(s): source/supp_content.tex:15-23 (Eq. (S2)).
Conclusion
Derivation (derivation.md): spectral decomposition S=sum_k lambda_k |r_k>><
Verification details
Derivation excerpt: One cycle is the linear superoperator $S$ acting on $\mathrm{vec}(\rho)$ (column stacking), established in C040. Iterating $N$ cycles is therefore $$\mathrm{vec}(\rho_N) = S^N\,\mathrm{vec}(\rho_0), \qquad \rho_N = \mathrm{unvec}\!\left(S^N\,\mathrm{vec}(\rho_0)\right).$$
Executable rerun: run.py exited 0 in 0.531s; log verification/C042/attempts/R002/run.log.
Output excerpt:
[optimal] S^N vec == repeated step err: 7.770384787854966e-17
[optimal] lambda_max=0.876964 (complex 0.8770-0.0000j) N0=-1/log=7.6168
[optimal] fit slope=-0.131289 log(lambda_max)=-0.131289 -1/slope (N0_fit)=7.6168 C0=0.8892
[optimal] max rel residual (C0 lam^N vs sim, N>=20): 1.085e-09
[generic] S^N vec == repeated step err: 8.037642502610834e-17
[generic] lambda_max=0.912953 (complex 0.9130+0.0000j) N0=-1/log=10.9805
[generic] fit slope=-0.091071 log(lambda_max)=-0.091071 -1/slope (N0_fit)=10.9805 C0=0.8924
[generic] max rel residual (C0 lam^N vs sim, N>=20): 7.884e-06
PASS