基于连续变量的经典-量子信息共信道同传系统拉曼散射影响分析

经典-量子共信道同传是量子保密通信关键应用技术之一，其能够解决当前量子信息与经典信息需不同光纤分别传输的难点问题，可显著降低应用成本。本文针对基于波分复用技术的连续变量量子密钥与经典信息同传的方案，定量分析了系统拉曼散射噪声特性，在前向和后向两种不同经典信息传输模式下，仿真对比研究了拉曼散射噪声对系统安全密钥率的影响。结果表明：经典信息采用前向传输模式时系统安全密钥率明显大于后向传输模式；在固定信道输入功率时，短距离通信时拉曼散射噪声对安全密钥率的影响较小，随距离的增长，拉曼噪声影响不可忽略；在固定通信距离时，在一定数值范围内的额外噪声对系统的安全密钥率影响较小，在L=50km时，此数值为0.07N0 。

Analysis of Raman scattering in multiplexed classical and quantum transmission channel system based on continuous variable

The multiplexed classical and quantum transmission was one of the key application technologies of quantum secret communications, which could solve the problem that quantum information cannot transmit with classical information in a single fiber, it could reduce the application cost significantly. Aiming at the scheme that multiplex continuous variable quantum key with classical information based on WDM technology, this text quantitative analysis the characteristic of Raman scattering in the system ,under the condition that the classical information propagate in the forward mode or in the backward mode, and comparative study the vary of the secure key rate due to Raman scattering noise. The analysis shows that, the secure key rate in the forward classical transmission mode system is larger than it in the backward classical transmission mode system; if classical input power is a fixed value, the secure key rate variation induced by Ranman scattering in short distance is very small, the influence is more and more large when the distance increase; and the change triggered by the noise within a certain range of values could be ignored. The influence induced by noise in the range of 0.07N0 can negligible when the transmission distance is 50km.