经典-量子共纤传输的单光子量子密码系统研究

With the engineering development of quantum cryptography, quantum cryptography systems that transmit all signals with single fiber become more and more attractive. However, the intensity of classical signals is more than seven orders of magnitude stronger than the intensity of quantum signals, which causes terrible disturbance on quantum signals if classical and quantum signals co-transmit in the same fiber. And, related researches on this area is very scattered and limited. In combination with our own conditions and advantages, we will take comprehensive research on the single-photon quantum cryptography system with classical and quantum signals co-transmission in the same fiber. First, focusing on the nonlinear disturbance from the classical signals, and through theoretic analysis and experimental measurement, we will construct a theory model of the single-photon quantum cryptography system with classical and quantum signals co-transmission in the same fiber. Then, based on our own two kinds of the single-photon quantum cryptography system, we will explore effective solutions to suppress noise and extract quantum signals, in this stage，we would get positive results to satisfy the need of engineering development. Finally, through organic combination of several noise suppression technologies, we will design a single-photon quantum cryptography system with classical and quantum signals co-transmission in the same fiber, this quantum cryptography system has high compatibility and compatibility. The fruits of this project will promote the engineering development of quantum cryptography, and provide new ideas and methods for extremely strong and weak signals co-transmission in the same fiber.

随着量子密码技术实用化的推进，单根光纤完成全部通信的量子密码系统显得越发具有吸引力。但是经典信号的光强超过量子信号七个数量级还多，共纤传输会对量子信号造成极大干扰，目前国内外相关研究较为零散，且具有较多的局限性，本项目拟以经典-量子共纤传输的单光子量子密码系统为研究对象，结合自身优势，开展综合性的科学研究。项目将围绕解决共纤传输时经典信号对量子信号的非线性干扰这一科学难题而展开，通过理论分析和实验测试，构建经典-量子共纤传输单光子量子密码系统的理论模型；通过结合项目组已有的两类单光子量子密码系统，探索抑制干扰和提取量子信号的有效方案，形成阶段性成果，初步满足实用化需求；最终通过综合性研究，将多种噪声抑制技术有机结合，设计并实现具有较高兼容性和可靠性的经典-量子共纤传输的单光子量子密码系统。项目的研究成果将促进实用化量子密码系统的研究，为极强信号与极弱信号共纤传输提供新的思路和方法。

量子密码技术中密钥分发的协商过程和加密应用过程都离不开经典通信。为推进量子密码技术的实用化，本项目将单根光纤完成经典和量子全部通信作为研究目标，通过理论模拟和实验测试相结合的方式，设计并实现了经典-量子共纤传输的单光子量子密码系统。经典信号的光强超过量子信号七个数量级还多，其在光纤介质中的非线性效应，特别是自发拉曼噪声会对量子信号的探测造成极大的干扰，项目从波分复用、时分复用和空分复用三个层面着手，探索抑制干扰和提取量子信号的有效方案，降低经典信号传输过程中对量子信号探测造成的干扰。而针对不同的应用场景，骨干线路的高速量子密码系统，接入网的中低速量子密码系统，甚至不同的覆盖范围和不同的光纤类型，项目组均进行了测试分析。此外，对新出现的具有高误码容忍的协议，在经典-量子共纤传输系统方面具有较好的发展前景，项目也展开研究。项目的成果不仅为后续实用化研究积累了基本数据和设计原型，也为极强信号与极弱信号共纤传输研究奠定了理论和实验基础。