水下与水上平台间的量子密钥分发系统关键技术研究

The underwater safety communication is of great strategic significance for marine safety and marine resources development. It can well meet the requirements of military secret communication between underwater submarine and aircraft, satellite, etc. that quantum key distribution (QKD) between underwater and above surface terminals is implemented. At present, the research of underwater quantum communication is just in the beginning, and it is still in the theoretical research stage and there has been none result reported about experimental research. Both the United States and China researchers have shown that the 100m distance QKD is feasible under the clear seawater. However, underwater QKD has many problems, such as large channel loss, strong background noise in the large field of view, and immature blue-green laser source technology for QKD. .This project plans to carry out key technologies research from a variety of perspectives, including theoretical simulation of channel model, fast narrow-pulse blue-green laser source, underwater high precision time synchronization between sender and reciever and time-gate filtering, etc. A high efficiency and low noise quantum channel link will be established between underwater and above surface terminals. A prototype demonstration of underwater QKD experiment will be completed to verify the feasibility of QKD via underwater and above surface terminal. This project will accumulate several key technologies for the future practical quantum secure communication between submarines, unmanned underwater vehicles and above surface terminals and promote the research and practical development of underwater quantum communication.

基于海水介质的水下安全通信对海洋军事安全和海洋资源开发有着重要战略意义。基于水下与水上平台间的量子密钥分发的研究实现可以很好的满足水下潜艇与飞机、卫星等水上目标军事保密通信需求。目前水下量子通信研究刚刚起步，还处于理论研究阶段，尚未见实验研究成果报道。美国和我国研究人员均已理论计算表明了清澈海水下100m距离量子密钥分发是可行的。然而，水下量子密钥分发面临信道损耗大、大视场角接收下背景噪声强、蓝绿量子光源技术不成熟等难题。.本项目从信道模型理论模拟、高速窄脉冲蓝绿量子光源、水下高精度时间同步和滤波等多角度开展关键技术研究，建立水下与水上平台间的高效率低噪声量子信道链路。通过水下与水上平台之间的量子密钥分发的可行性验证，完成原型实验演示，为未来实用化对潜艇、无人水下航行器等水下目标的量子保密通信积累关键技术，推动水下量子通信的研究和实用化发展。

基于水下与水上平台间的量子密钥分发的研究实现可以很好的满足水下潜艇与飞机、卫星等水上目标保密通信需求。本项目面向这一目标，开展了若干关键技术攻关研究，包括跨波动海水界面的量子信道影响分析、蓝绿波段量子光源技术、水下大视场光学接收天线、高精度时间同步等。分析结果表明波动海水界面引起的光子偏振态改变对量子通信误码率影响有限。实现了重复频率1MHz，脉冲宽度14ns的532nm量子诱骗态光源，实现了高效率倍频的全固态激光器技术。研制了百mrad级接收视场角的水下光学接收天线。实现了一套基于FPGA TDC的高速相位同步方案，相位同步精度达到3.8ps。研制了一整套完整的面向水上-水下量子密钥分发的原型系统，并实现了原型实验演示，在50cm真实海水样品信道下实现了量子密钥分发，积累安全密钥4.8 kb，平均安全密钥产生率为6.82 bps，误码率为3.74%。本项目的研究成果表明水下与水上平台开展量子密钥分发具有可行性，相关技术的积累推动了水下量子通信研究的进一步发展，对于海洋军事安全和海洋资源开发有着重要战略意义。