Investigation On Optimization Of The Quantum Cryptography Communication System And Quantum Logic Gates

Quantum information is an active research field, which can be used to develop the next generation computer and communication systems, and it will play a more and more important role in information technology. This thesis mainly focuses on investigation on the quantum cryptography communication system and quantum logic gates. Quantum cryptography communication system is based on principles of quantum mechanics, thereby it can provide absolute security of information. Quantum logic gate is a functional component which realizes solid state quantum information processing. This thesis consists of two main parts: the optimization of quantum cryptography communication system and the construction and manipulation of quantum logic gate. The main works are given as follows:Firstly, analysis of quantum cryptography communication system according to a certain cryptography protocol is carried out, including connecting method and detector. Based on the above, the origins of noise, especially the influences of input pulse parameters and the optical fiber in the system, are investigated. Therefore, the optimal scheme of quantum cryptography communication system is presented. Furthermore, the performance of the optimal system is verified with program in MATLAB.Secondly, the characteristic of different quantum logic gates and quantum bit is analyzed. Coupled-resonator optical waveguides (CROW) can be constructed through flexible design and doping of photonic crystal. Then the quantum logic gate can be implemented based on the CROW. Finally, the method of manipulation of quantum state with various elements is discussed and the mathematical simulation of it is demonstrated.