发表机构
School of Quantum Technology, Defence Institute of Advanced Technology（量子技术学院，国防先进技术研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究评估自由空间QHQ波片与光纤FPC两种被动偏振补偿技术，通过逐路径优化实现光纤偏振纠缠光子补偿，恢复高可见度、高保真度纠缠，为短距离量子通信链路提供系统框架。
AI 中文摘要
通过光纤实现纠缠分发对量子通信网络至关重要，但光纤传输会改变光子偏振，进而改变偏振纠缠态的观测关联，因此需要偏振补偿以在测量基中恢复所需的纠缠态。本文实验评估两种被动偏振补偿技术：自由空间四分之一-二分之一-四分之一（QHQ）波片结构，以及光纤内置三桨光纤偏振控制器（FPC）。通过系统的逐路径优化程序，对每一路下转换光子路径的偏振变换进行独立补偿。采用两种技术均成功恢复高质量偏振关联与纠缠，在三个相互无偏基中可见度超过93%，保真度高于94.5%。结果表明，基于自由空间波片与基于光纤控制器的补偿效果相当，为实验室及短距离量子通信链路建立了系统框架。
英文摘要
Entanglement distribution through optical fibers is essential for quantum communication networks; however, fiber transmission can alter photon polarization and modify the observed correlations of polarization-entangled states, necessitating polarization compensation to recover the desired entangled state in the measurement basis. Here, we experimentally evaluate two passive polarization compensation techniques: a free-space Quarter-Half-Quarter (QHQ) waveplate configuration and an in-fiber three-paddle Fiber Polarization Controller (FPC). The polarization transformation along each downconverted-photon path is independently compensated through a systematic path-by-path optimization procedure. Using both techniques, we recover high-quality polarization correlations and entanglement, with visibilities exceeding $93\%$ in three mutually unbiased bases and fidelities above $94.5\%$. The results demonstrate comparable restoration using free-space waveplate-based and fiber-based control, establishing a systematic framework for laboratory and short-reach quantum communication links.
Comments12 Pages, 4 Figures and 13 images
