Hybrid Quantum Private Communication With Continuous-variable And Discrete-variable Signals

In modern society, information security is an important research topic.Quantum cryptography is an emerging discipline that is based on information security.It brings development opportunity to cryptography and communication disciplines.It has changed the conventional encryption which is only dependent on mathematical and logical way and opened up new ideas and methods of the cryptography disciplines based on the physical mechanisms. In addition, its unconditional security which is based on physical characteristics brings it unparalleled advantage.From the viewpoint of future trends, whether in people’s communication life, or in the military field of country, quantum private communication has great application perspective and commercial values.The quantum key distribution technology is the most popular in quantum secure communication.The quantum key distribution technology is divided into discrete-variable quantum key distribution technology and continuous-variable quantum key distribution technology. Discrete variable quantum key distribution technology is the first to be widely studied and achieved a very significant achievement. With the gradual study of the discrete variable quantum key distribution technology, people discovered and began to study continuous variable quantum key distribution technology.Due to the coherent state is significantly easier to obtain, the continuous variable quantum key distribution technology also achieved significant results.Currently, the QKD system implementing with discrete-variable or continuous-variable has been entering the practical application era. From the viewpoint of the quantum private communication, if various QKD techniques could share a same optical networking infrastructure, one may integrate the CVQKD and/or DVQKD systems into the existing fiber telecommunication network system. Clearly, this way will be an optimal way for QKD application in optical fiber network since this way may reduce the communication complexity of the network system.This paper focuses on exploring the mutual influence among the continuous-variable quantum signal, the discrete-variable quantum signal and the classic optical signal.The main researches are listed as following:K We design and complete the total optical circuits of a fiber-based discrete-variable quantum key distribution system. We describe the design of the optical system in detail, including the structure of the optical components and the control of polarization.The single mode fiber is used in the system. Then we introduce the control block of the system and test the key parameters of the optical device in the system, and evaluate the performance of the optical system.2n We design a hybrid quantum communication network models based on the continuous-variables quantum key distribution,discrete-variable quantum key distribution and classic optical system. This paper builds a hybrid access network system,which uses a wavelength multiplexing technology to achieve the continuous variables, discrete variables and the classic three-way independent optical signal’s parallel transmission in the same fiber. This paper systematically analyzes the generation and modulation of the multi-channel signal, and then describes the theoretical model based on the Gaussian modulation and the BB84protocol in detail.3-. We experimentally investigated the mutual effects among the discrete-variable quantum key distribution, the continuous-variable quantum key distribution and the classic optical fiber communication via a fiber channel. We consider the relative errors caused by the single photon signal on the Gaussian modulation CVQKD protocol, Clearly, if a same result is obtained, we may judge that the CVQKD system is not sensitive to the discrete-variable signal.However,if a different result is obtained, the CVQKD system is influenced by the discrete-variable signal. And then we consider the QBER caused by the coherent state signal as well as the local oscillator signal on the BB84QKD protocol. In addition, the influence of the classic optical signal on the DVQKD system is also investigated.If the same QBER is obtained, we will know that the discrete-variable quantum signal is not sensitive to continuous-variable quantum key distribution and the classic optical signals.