The Differential Phase Shift Of Quantum Key Distribution

With the development of information science and technology, more and more scientists and engineers pay attention to the security of information transmission nowadays. In recent years, quantum cryptography has attracted wide concern and make great progress in theory and experiment, due to its peculiar characteristics of perfect security in communication. A novel protocol—differential phase shift quantum key distribution (DPS-QKD), proposed by Kyo Inoue, Edo Waks and Yoshihisa Yamamoto, is described and discussed in this dissertation. A scheme of quantum random number generator is proposed and realized by our research group.The research progress of QKD and the significance of random number is discussed firstly. The fundamental concept and theory of quantum cryptography is introduced respectively. The three mainstream protocols in QKD—BB84、 E91and B92are discussed and analyzed later. Then, a novel and feasible scheme of a quantum random number generator (QRNG) is presented in detail. The QRNG based on the process of splitting a beam of photons by using symmetrical Y-branch waveguide is realized. The choice of a single photon between the two outputs of the Y-branch is physical random. Photon stream is detected by single-photon detectors, and a string of binary random numbers(i.e. raw quantum key) can be generated by utilizing high-speed data acquisition circuits. At last, the specific scheme of DPS-QKD, as well its security, is introduced and analyzed. The DPS-QKD system is successfully demonstrated in experiment.