Qian Xuerui, Zhang Chunhui, Yuan Huawei, Zhou Xingyu, Li Jian, Wang Qin
Institute of Quantum Information and Technology, Nanjing University of Posts and Telecommunications, Nanjing 210003, China.
Broadband Wireless Communication and Sensor Network Technology, Key Lab of Ministry of Education, NUPT, Nanjing 210003, China.
Entropy (Basel). 2022 Apr 23;24(5):592. doi: 10.3390/e24050592.
Twin-field quantum key distribution (TF-QKD) can break the repeaterless linear bound and possess the measurement-device-independent security, and thus seems very promising in practical applications of quantum secure communication. In most reported TF-QKD protocols, light sources are assumed to possess trusted and fixed photon number distributions (PND), which are unrealistic assumptions in practical applications. Fortunately, the light source monitoring (LSM) method is proposed to circumvent this problem by actively adjusting the attenuation coefficient and monitoring the photon number distribution of light sources. However, the active light source monitoring (ALSM) method may induce additional modulation errors due to imperfect attenuation devices, deteriorating practical performances of TF-QKD systems. In this manuscript, we propose a passive light source monitoring (PLSM) scheme for TF-QKD, and employ the sending-or-not-sending (SNS) TF-QKD as an example for illustration. Simulation results show that our present work can greatly exceed both the original SNS protocol and the ALSM scheme when light source fluctuations and modulation errors are taken into account.
双场量子密钥分发（TF-QKD）能够突破无中继线性限制并具备测量设备无关安全性，因此在量子安全通信的实际应用中似乎非常有前景。在大多数已报道的TF-QKD协议中，假设光源具有可信且固定的光子数分布（PND），而这在实际应用中是不现实的假设。幸运的是，提出了光源监测（LSM）方法，通过主动调整衰减系数并监测光源的光子数分布来规避此问题。然而，主动光源监测（ALSM）方法可能由于衰减设备不完善而引入额外的调制误差，从而恶化TF-QKD系统的实际性能。在本论文中，我们提出了一种用于TF-QKD的被动光源监测（PLSM）方案，并以发送-不发送（SNS）TF-QKD为例进行说明。仿真结果表明，当考虑光源波动和调制误差时，我们目前的工作能够大大超越原始的SNS协议和ALSM方案。
