Quantum Key Distribution Systems And Quantum Random Number Generator

During information age, information security, which is now guarded by modern cryptography, always is of great importance for every nation, every group and every body. But with the development of quantum information sciences, maybe modern cryptography is not really secure any more under the attack of quantum computer in future. At the same time, quantum cryptography, based upon Heisenberg's Uncertainly principle, which guarantees its absolute security.Our Quantum Cryptography research group focuses on developing a fiber optic Quantum Key Distribution (QKD) system based on phase encoded single photons. My work during past two years in this group is reported in this article.Firstly the principle of QKD is introduced, its previous development and prospect is described secondly. Our experimental work is the main part. After the description of the framework of our system, the implementation of its basic modules, including single photon source, single photon detectors, optical fiber phase modulator and data acquisition and processing program, is reported. Our system is based on BB84 protocol. The working wavelength is 850nm and transmission distance is 1.1Km. My own job concentrates on single photon detector, data acquisition and processing program.At the same time, I have implemented a Quantum Random Number Generator based on the intrinsic randomness of quantum mechanics, which will be used in our future QKD systems and can be developed into a kind of product. The random events are realized by the choice of single photons between the two outputs of a beamsplitter. Its byte generation rate is about 40KHZ and the generated byte sequence can pass randomness test.