Zhu Yiwu, Mao Lei, Hu Hui, Wang Yijun
School of Automation, Central South University, Changsha 410083, China.
Entropy (Basel). 2023 Feb 7;25(2):307. doi: 10.3390/e25020307.
Continuous variable quantum key distribution (CVQKD) can be potentially implemented through seawater channels, whereas the involved oceanic turbulence has a negative effect on the maximal transmission distance of quantum communication systems. Here, we demonstrate the effects of the oceanic turbulence on the performance of the CVQKD system and suggest an implementation feasibility of the passive CVQKD through the oceanic turbulence-based channel. We achieve the channel transmittance characterized by the transmission distance and depth of the seawater. Moreover, a non-Gaussian approach is used for performance improvement while counteracting the effects of excess noises on the oceanic channel. Numerical simulations show that the photon operation (PO) unit can bring reductions of excess noise when taking into account the oceanic turbulence, and hence results in performance improvement in terms of transmission distance and depth as well. The passive CVQKD explores the intrinsic field fluctuations of a thermal source without using an active scheme and hence has a promising application in chip integration for portable quantum communications.
连续变量量子密钥分发（CVQKD）可以通过海水信道潜在地实现，然而，其中涉及的海洋湍流对量子通信系统的最大传输距离有负面影响。在此，我们展示了海洋湍流对CVQKD系统性能的影响，并提出了通过基于海洋湍流的信道实现无源CVQKD的可行性。我们获得了以海水传输距离和深度为特征的信道透射率。此外，在抵消海洋信道上过量噪声影响的同时，采用非高斯方法来提高性能。数值模拟表明，考虑海洋湍流时，光子操作（PO）单元可以降低过量噪声，从而在传输距离和深度方面也提高了性能。无源CVQKD无需使用有源方案即可探索热光源的固有场涨落，因此在便携式量子通信的芯片集成方面具有广阔的应用前景。
