基于量子存储的长距离测量设备无关量子密钥分配研究∗

摘要

We propose a long distance measurement-device-independent (MDI) quantum-key-distribution (QKD) with quan-tum memory, and analyze the relationship between the key generation rate and the storage efficiency of quantum memory. Our protocol is considered and compared with MDI-QKD without quantum memory. We present general formulas for our protocol with three-intensity decoy states. The simulation results show that the maximum secure distance supported by MDI-QKD with quantum memory is about 500 km, while the maximum secure distance of MDI-QKD without quan-tum memory is only 216 km. With certain limits, prolonging the time of maintaining the necessary quantum fidelity can increase security key transmission distance. Furthermore, the protocol is robust against device imperfection such as quantum memory decoherence effects, which can be easily applied to practical QKD system.%针对量子中继器短时间内难以应用于长距离量子密钥分配系统的问题,提出了基于量子存储的长距离测量设备无关量子密钥分配协议,分析了其密钥生成率与存储效率、信道传输效率和安全传输距离等参数间的关系,研究了该协议中量子存储单元的退相干效应对最终密钥生成率的影响,比较了经典测量设备无关量子密钥分配协议和基于量子存储的测量设备无关量子密钥分配协议的密钥生成率与安全传输距离的关系。仿真结果表明,添加量子存储单元后,协议的安全传输距离由无量子存储的216 km增加至500 km,且量子存储退相干效应带来的误码对最终的密钥生成率影响较小。实验中可以采取调节信号光强度的方式提高测量设备无关量子密钥分配系统的密钥生成率,为实用量子密钥分配实验提供了重要的理论参数。