2026-10-22 · arXiv Quantum Physics
arXiv:2610.30098v1 Announce Type: new
Abstract: A two-level emitter chirally coupled to a waveguide imprints a $\pi$ conditional phase on a two-photon pulse, a key component assumed in quantum photonic neural network architectures, but whether it survives the pure dephasing of a solid-state emitter is unknown, since no two-photon scattering treatment includes it. We derive the dephased two-photon amplitude in closed form and validate it against an independent Fock-state master equation. The conditional phase is pinned at exactly $\pi$ at every dephasing rate examined: dephasing destroys the amplitude carrying the nonlinear phase rather than rotating it. The one- and two-photon channels are not attenuated equally, so dephasing does not simply scale the node down but reweights it between photon-number sectors---an error no phase setting can train away. The standard factorization of two-photon correlators, exact for arbitrary loss, fails at first order in $\gamma_\phi$, discarding $16$--$81\%$ of pairs over $\gamma_\phi/\gamma=0.1$--$1$.
原文链接：https://arxiv.org/abs/2610.30098
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