Li Wei, Wang Le, Zhao Shengmei
Nanjing University of Posts and Telecommunications, Institute of Signal Processing and Transmission, Nanjing, 210003, China.
Nanjing University of Posts and Telecommunications, Key Lab Broadband Wireless Communication and Sensor Network, Ministy of Education, Nanjing, 210003, China.
Sci Rep. 2019 Oct 29;9(1):15466. doi: 10.1038/s41598-019-51848-9.
Two time-reversal quantum key distribution (QKD) schemes are the quantum entanglement based device-independent (DI)-QKD and measurement-device-independent (MDI)-QKD. The recently proposed twin field (TF)-QKD, also known as phase-matching (PM)-QKD, has improved the key rate bound from O(η) to O[Formula: see text] with η the channel transmittance. In fact, TF-QKD is a kind of MDI-QKD but based on single-photon detection. In this paper, we propose a different PM-QKD based on single-photon entanglement, referred to as single-photon entanglement-based phase-matching (SEPM)-QKD, which can be viewed as a time-reversed version of the TF-QKD. Detection loopholes of the standard Bell test, which often occur in DI-QKD over long transmission distances, are not present in this protocol because the measurement settings and key information are the same quantity which is encoded in the local weak coherent state. We give a security proof of SEPM-QKD and demonstrate in theory that it is secure against all collective attacks and beam-splitting attacks. The simulation results show that the key rate enjoys a bound of O[Formula: see text] with respect to the transmittance. SEPM-QKD not only helps us understand TF-QKD more deeply, but also hints at a feasible approach to eliminate detection loopholes in DI-QKD for long-distance communications.
两种时间反演量子密钥分发（QKD）方案是基于量子纠缠的设备无关（DI）-QKD和测量设备无关（MDI）-QKD。最近提出的双场（TF）-QKD，也称为相位匹配（PM）-QKD，已将密钥率界限从O(η)提高到O[公式：见正文]，其中η为信道透射率。实际上，TF-QKD是一种基于单光子探测的MDI-QKD。在本文中，我们提出了一种基于单光子纠缠的不同的PM-QKD，称为基于单光子纠缠的相位匹配（SEPM）-QKD，它可以被视为TF-QKD的时间反演版本。标准贝尔测试的探测漏洞在该协议中不存在，而在长传输距离的DI-QKD中经常出现，因为测量设置和密钥信息是编码在本地弱相干态中的相同量。我们给出了SEPM-QKD的安全性证明，并在理论上证明了它对所有集体攻击和分束攻击都是安全的。仿真结果表明，密钥率相对于透射率具有O[公式：见正文]的界限。SEPM-QKD不仅有助于我们更深入地理解TF-QKD，还暗示了一种消除长距离通信中DI-QKD探测漏洞的可行方法。
