实用化态制备误差容忍参考系无关量子密钥分发协议

Study of practical state-preparation error tolerant referenceframeindependent quantum key distribution protocol

在实际量子密钥分发系统中,实际器件不理想可能导致系统存在安全性隐患.比如,光源端的编码设备不理想,可能导致量子态存在误差;探测端的探测器存在缺陷,可能产生后脉冲或死时间效应,从而影响系统的实际安全性.因此,本文提出了一种同时考虑光源端和探测器缺陷的实用化态制备误差容忍参考系无关量子密钥分发协议.本文采用三强度诱骗态方案开展建模分析与数值仿真计算.本协议通过利用虚拟态方法估算相位误码率,降低了态制备误差对密钥率的影响;同时对探测器端的缺陷进行相应参数刻画,具有较强的鲁棒性,为参考系无关量子密钥分发协议的实际应用提供了重要参考价值.

Quantum key distribution(QKD)enables the establishment of shared keys between two distant users,Alice and Bob,based on the fundamental principles of quantum mechanics,and it has proven to possess information-theoretic security.In most of QKD systems,Alice and Bob require a shared reference frame,and real-time calibration of the reference frame increases system costs and reduces its performance.Fortunately,the reference-frame-independent QKD protocol has been proposed,overcoming reference-frame drift issues and receiving widespread attention.However,in practical QKD systems,the non-ideal characteristics of realistic devices introduce certain inconsistency between the theory and the practice.In real-world quantum key distribution systems,device imperfections can lead to security vulnerabilities,thereby reducing system security.For example,imperfections in the encoding apparatus at the source end may result in errors in the quantum states.The inherent defects in the detection part may cause after-pulse effects and dead-time effects,thus reducing the key rate.Therefore,in this work,we propose a practical state-preparation error tolerant reference-frame-independent quantum key distribution protocol by taking imperfections in both the source and the detectors into account.Moreover,a three-intensity decoy-state scheme for modeling analysis and numerical simulations is employed.In this protocol,we reduce the influence of state-preparation errors on the key rate by utilizing virtual state methods to precisely estimate the phase-error rate.Furthermore,by characterizing the effects of after-pulses and dead-time on the key rate,our protocol exhibits higher robustness and can effectively address issues related to detector imperfections.This approach can also be extended to other quantum key distribution protocols with higher security levels,such as measurement-device-independent quantum key distribution protocol and twin-field quantum key distribution,further mitigating the influence of device imperfections on practical implementation of QKD system.Therefore,our present work provide important reference value for putting the quantum key distributions into practical application.