Free-space quantum key distribution (QKD) with modulating retro-reflectors (MRR) is adopted to simplify the pointing requirements in practical experiment, which has the potential for mobile and flexible QKD platforms. However, this protocol suffers double-pass weak turbulence that may affect the performance of the QKD experiment in free-space links. In this paper, the free-space QKD with MRR under double-pass correlated turbulent channel is analyzed to examine the relationship between system performance and two parameters of the fading correlation coefficient and the turbulence intensity. The threshold post-selection method (P-RTS) is extended to MRR-QKD scheme under correlated turbulent channel and the simulations show that the P-RTS method is effective to alleviate the effect of atmospheric turbulence and suitable for the situation of double-pass correlated turbulent channel to make the protocol more practical in actual environment.

采用具有调制后向反射器（MRR）的自由空间量子密钥分发（QKD）可以简化实际实验中的指向要求，这对于移动和灵活的QKD平台具有潜力。但是，此协议遭受双通弱湍流，这可能会影响自由空间链接中QKD实验的性能。本文分析了双通相关湍流通道下具有MRR的自由空间QKD，以检验系统性能与衰落相关系数和湍流强度两个参数之间的关系。