This paper reports on the experimental diagnostics of an entanglement-swapping protocol by means of collective entanglement witness. Our approach is suitable to detect disturbances occurring in the preparation of quantum states, quantum-communication channels, and imperfect Bell-state projections. More specifically, we demonstrate that our method can distinguish disturbances such as depolarization, phase damping, amplitude damping, and imperfect Bell-state measurement by observing four probabilities and estimating collective entanglement witness. Since entanglement swapping is a key procedure for quantum repeaters, quantum relays, device-independent quantum communications, and entanglement-assisted error correction, this can aid in faster and practical resolutions of quality of transmission related problems as our approach requires fewer measurements than other means of diagnostics.

中文翻译：

---

集体纠缠测试对纠缠交换的实验诊断

本文报告了通过集体纠缠目击者进行纠缠交换协议的实验诊断。我们的方法适用于检测在准备量子态，量子通信通道和不完善的贝尔态投影时发生的干扰。更具体地说，我们证明了我们的方法可以通过观察四个概率并估计集体纠缠证人来区分诸如去极化，相位阻尼，幅度阻尼和不完善的贝尔状态测量等干扰。由于纠缠交换是量子中继器，量子中继，与设备无关的量子通信和纠缠辅助纠错的关键过程，