The Generation Of Entanglement State And The Implementation Of Phase Gate Base On Faraday Rotation And Cavity Qed System

The classical information systems are close to the development limit for the rapid development of it's integration, and the quantum effect becomes more and more evidence. In order to break the limit of classical information systems, quantum information science is established. As a new technology, quantum information mainly includes quantum computation and quantum communication. Entanglement is the crucial means of the quantum communication, and the multi-qubit entanglemrnt states especially play the role of basic channel in the quantum communication. The phase gate is necessary for implementing the quantum computation. So, the study of the physical realization of quantum entanglement state and phase gate is very important for quantum information science.The cavity QED system plays a significant role in Quantum information process because it is a ideal physical implementation system. We can achieve many quantum information processes in low-Q cavity by applying the Faraday Rotation mechanism to the Cavity QED system, and this also would great lower experimental difficulties. So it is of great vaule to study the quantum information process based on the Faraday Rotation mechanism and the Cavity QED system. Because of the above reasons, I chose this field for my graduate study. The main contents of this dissertation include three aspects.1. Based on the input-output relation of the cavity and the Faraday Rotation mechanism, we propose a scheme for generating the n-atom GHZ state. In the scheme, the n-atom trapped respectively in n spatially separate cavities without strong coupling. We just need a single photon interaction with the atom-cavity system in every step, it means that we just need single photon detection but many photons detection. All of this merits made our scheme much more efficient and easy to be realized. The successful probabilities of our protocol approach unity in the ideal case.2. Using the same principle above, we propose a scheme for generating the 1 Dmension (1D) and 2D n-atom cluster state. The atomic spontaneous emission is suppressed by encoding the information in the ground state. This scheme could be implement in low-Q cavity, and the success rate is good in the ideal case.3. We propose a scheme for realizing two photons phase gate in the case of low-Q factor and weak coupling. Our scheme could be implemented experimentally with high-quality single photons resources and the Technology of Repeatting The Operations Until To Success.