Dissertation > Mathematical sciences and chemical > Physics > Theoretical Physics > Quantum theory

Continuous Variable Quantum Cryptography Communication Experiment.

Author DaiWenChao
Tutor ZengGuiHua
School Shanghai Jiaotong University
Course Communication and Information System
Keywords continuous variable quantum key distribution quan-tum stream encryption real-tim voice integrated secure system
CLC O413
Type Master's thesis
Year 2012
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Quantum secure communication technology is an emerging discipline. It haschanged the traditional method of encryption, which is based on mathematics theory.The Quantum secure communication technology brings in complete revolution intothe communication discipline and The technology based on quantum theory will def-initely play a more and more important role in people’s daily lives. The bright future,enormous commercial value and the great advantage in military field, attract manyuniversities, governments and research institutes to invest huge resources to make in-tensive study in this subject. In recent years, many novel quantum communicationprotocols are put forward, the security verification is gradually improved and reportsabout prototypes and networks of quantum communication emerges a lot. It is safeto conclude that in the future, there will be a great development opportunity in thequantum secure communication field.Compared to the discrete variable quantum cryptography, the continuous vari-able quantum cryptography has great advantages, such as lower cost, larger capaci-ty, reasonable stability and higher secure key rate. The continuous variable quantumcryptography will definitely lead the long-term development of this discipline. In thisthesis, we discuss the continuous quantum cryptography in detail. Key technologiesand subject difficulties are researched. The secure analysis, protocol design, opticallayout, software architecture, hardware development and prototype manufacture areall detailedly and deeply introduced. Several innovative technologies are presented inthis thesis.The following work are presented in this thesis.(1) The research on quantum key distribution and quantum stream encryption, both protocol are based on continuous variable. In the two different experiment, weintroduce all the design details, from theoretical secure analysis to the practicaloptical layout. The design details are organized and presented in modularizedway. Several factors which in?uence the stability and error rate are introducedand corresponding solutions are put forward, such as phase compensation algo-rithm. In addition, The experiment results of these two system are given in thisthesis. The sifted key rate with reverse reconciliation is 8.6 and 3.9 kb/s in thequantum key distribution scheme under the individual attack and the collectiveattack, respectively. The quantum stream encryption system with a 500 kb/smodulation rate over 27.2 km of optical fiber can make clear real-time voicecommunication and transmit txt, photo and other data on a error rate level of10?4.(2) The design of quantum integrated secure communication platform. An inte-grated quantum secure communication system is experimentally investigated.Two quantum communication protocols are involved in the presented system.One is used for generating the secret key which is obtained using continuousvariable quantum key distribution scheme, and the other serves to encrypt anddecrypt the stream private data using a pure quantum cryptographic algorithm.The two parts share weak coherent light source and detection node, achieving a“All-Quantum”communication platform. The design details of this integratedplatform are presented. The optical layout and software development are intro-duced. Additionally, some key problems in prototype development are explainedand resolved.

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