The Key Technology Research In Continuous Variable Quantum Key Distribution System

Information security is an important research topic; a widely usedmathematical cryptography relies on mathematical problems without strictproof. However with the breakthrouths on the computing power of currentcomputers and the accelerated progress in the development of quantumcomputers, this information security system depends on the mathematicalpassword will be faced with severe challenges. People begin to look for a newencryption method to deal with the impending situation. Outstanding researchachievements in quantum realm make people focus on the quantum, and thenquantum cryptography is proposed. The emergence of quantum cryptographyhas opened up new ideas and new ways based on the physical mechanismabout cryptography. It brings development opportunity to cryptography andcommunication disciplines. Quantum cryptography is a nascent discipline, butits appearance changes the traditional encryption methods which are based onmathematical methods, and its unconditional security based on the physicalcharacteristics of quantum brings an unparalleled advantage. Quantumcryptography will play an important role in the field of communication. Greatprospects of quantum cryptography, especially in the military field, and itscommercial value will attract a lot of resources and manpower to conductresearch in universities, government and research institutions.Quantum key distribution is the most charismatic in quantumcryptography; this is based on the one-time pad encryption methods in classicencryption. If the key is secure, one-time pad encryption will be unconditionally secure. Quantum key distribution is mainly divided intodiscrete variable quantum key distribution technology and continuousvariable quantum key distribution technology. Discrete variable quantum keydistribution technology is the first quantum key distribution technology to bewidely study and achieved certain results. Compared with discrete variablequantum key distribution technology, continuous variable quantum keydistribution technology has its own unique congenital advantages. Thesecongenital advantages are mainly on the follow aspects. First on thepreparation of the information carrier, continuous variable quantum signal iseasily prepared, and the required equipment is cheap and eases to integrate.Secondly on the rate of key distribution, the key generation rate of continuousvariable quantum key distribution technology is very high. Thirdly on thestability of the system, continuous variable quantum key distribution systemhas very good communication stability and robustness.In this paper, the continuous variable quantum key distributiontechnology and system are illustrated. Hardware and software architecture ofcontinuous variable quantum key distribution system are in detail discussedand analyzed. The key technologies and subject difficulties are researched, thesynchronization protocol design and stability analysis of this system areillustrated in detail, and several innovative technical solutions are proposed.The major work is as follows in this paper:(1) The research on synchronization technology based on continuousvariable quantum key distribution system. A method of spontaneoussynchronization based on a continuous variable quantum key distributionsystem is proposed. This method can effectively overcome the disturbanceeffects which are generated by the environment in the transmission process ofcontinuous variable quantum. The scheme realizes the synchronizationbetween the sending terminal and the receiving.The mechanism of this synchronization scheme is theoretically introduced, and then based on acontinuous variable quantum key distribution system the feasibility of thissynchronization scheme is verify. The experiments on this system are carriedout. Based on the experimental data, the key performance indicators for thissynchronization scheme such as required time and successful probability areanalyzed.(2) The research on synchronous clock based on continuous variablequantum key distribution system. This paper begins with the characteristic ofcontinuous variable quantum key distribution system to elaborate the systemsynchronous clock requires. Several clock synchronization schemes areproposed based on these requirements, and the adjustion of every scheme tothe system architecture is analysed, the influence of every scheme to thesecurity of continuous variable quantum key is analysed. Then a detailedanalysis of the advantages and disadvantages of each approach are illustrated.(3) The research on phase compensation technology based on continuousvariable quantum key distribution system. A new phase compensation schemebased on continuous variable quantum key distribution system is proposed.This scheme can effectively eliminate the influences by the environmentalfactors in optical communication process. First the mechanism of this phasecompensation program is theoretically introduced, and then theimplementation is verified. The key performance indicators of this phasecompensation program are analysed.