发表机构
School of Mathematical and Physical Sciences, University of Sheffield（谢菲尔德大学数学与物理科学学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文分析基于发射器-腔系统的光子CZ门性能，发现单双光子波包形状优化存在权衡，导致平均保真度限制在约60%。
AI 中文摘要
本文分析了基于N个含二能级发射器的波导耦合腔的光子CZ门的性能。我们利用量子光学的输入-输出形式推导了单个腔的单光子和双光子散射矩阵，并利用SLH形式推导了N>1个腔的散射矩阵，从而能够计算CZ门的保真度。我们考虑两个输入高斯波包，它们以发射器-腔系统的双光子跃迁为中心，并发现优化单光子和双光子波包形状之间存在权衡。虽然对于大的发射器-腔耦合率，单光子波包得以保留（此时与单光子跃迁的重叠很小），但对于较小的耦合率（与腔衰减率乘以腔数相当），双光子波包获得了必要的π相移。我们发现，当对所有输入态进行平均时，这种权衡将CZ门的保真度限制在约60%。
英文摘要
In this paper we analyze the performance of photonic CZ gates based on N waveguide-coupled cavities containing two-level emitters. We derive single- and two-photon scattering matrices for one cavity using the input-output formalism of quantum optics and for N>1 cavities using the SLH formalism, allowing us to compute the CZ gate fidelity. We consider two input Gaussian wave packets that are centered on a two-photon transition of the emitter-cavity system, and find a trade-off between optimizing the single-photon and two-photon wave packet shape. While the single-photon wave packet is preserved for large emitter-cavity coupling rates, where there is little overlap with the single-photon transitions, the two-photon wave packet acquires the necessary $π$ phase shift for smaller coupling rates, comparable to the cavity decay rate multiplied by the number of cavities. We find that this trade-off limits the CZ gate fidelity to approximately 60% when averaging over all input states.
Comments30 pages, 9 figures
