基于Kolmogorov及非Kolmogorov湍流模型,分析了大气湍流对光子轨道角动量(OAM)的散射效应,得到了探测端不同OAM模式的概率。分析了两种湍流条件下OAM编码测量设备无关量子密钥分发(MDI-QKD)的密钥生成率与最大传输距离。仿真结果表明,当光束在大气信道传输时,光束的径向强度逐渐增大,湍流对光子OAM的散射效应逐渐增强,初始OAM发散为相邻OAM模式并趋于无规则分布,探测端测得初始OAM模式的概率不断减小。大气湍流下OAM编码MDI-QKD的最大传输距离比偏振编码MDI-QKD的长约10 km。

Based on the Kolmogorov and non-Kolmogorov turbulence models, the scattering effect of atmospheric turbulence on orbital angular momentum (OAM) is analyzed and the probabilities of different OAM modes are obtained at the detecting end. The key generation rates and the maximum propagation distances of OAM-encoded measurement-device-independent quantum key distributions (MDI-QKD) under two atmospheric turbulence conditions are analyzed. The simulation results show that, with the increase of the radial intensity during the light beams are propagating in the atmospheric signal channels, the scattering effect of the turbulence on OAM is gradually enhanced, and the initial OAM states are gradually diverted to the adjacent modes with a tendency of random distribution. The probabilities of initial OAM states at the detecting end decrease gradually. The maximum propagation distance for the OAM-encoded MDI-QKD is about 10 km longer than that for the polarization-encoded MDI-QKD under the atmospheric turbulence.