Fidelity For Quantum Systems Of Light-atoms Interaction

Quantum optics mainly researches on light field interaction with atoms and non-classical characteristics of light field. In resent years, with the governments pay more and more attention on quantum communication and quantum computer study, Fidelity for quantum state is also become an important research field. In This Thesis, the fidelity for the system of an effective two-level atom interaction with quantization light field with intensity dependent is the mainly research object.We mainly focus on the influence of the light field parameters, the two-level atom initial phase and detuning on the total system of light field and atom, the subsystem of the light field and the subsystem of the atom.In this thesis, the objects include three parts:Firstly, the Jaynes-Cummings model of atom interaction with field with intensity dependent is established. Secondly, the exact solution of the Jaynes Cummings model with intensity dependent was given, and the analytic expression of fidelity for total system, light-field system and atomic system were derived. Finally, the evolution laws of the fidelities for quantum states were analyzed with numerical method. In this thesis, the mainly content as follows:(1) The fidelity of quantum states were investigated on some systems in Jaynes-Cummings model with intensity dependent containing atomic motion under action of coherent state light field. A series of novel results were found such as:some influence on the fidelities of quantum states with atomic initial phase, velocity of atomic motion and field mode structure parameters et al.(2) The fidelity for quantum state of a two-level atom interaction with binomial light field systems were studied. Some influence factors on the fidelity were analyzed and discussed such as the atom phase, parameters of binomial light field, velocity of the atom and the parameter of the cavity. In addition, the variation and reason of the quantum state fidelity were discussed when the binomial field reduced to the coherent state light field, and how to get high fidelity was also illustrated.(3) The quantum state fidelity of entangled two-atom interaction with coherent state field with intensity dependent was studied. We found that the initial average photon number and detuning parameter have influence on the fidelity of systems.(4) The quantum state fidelity of atom interaction with nonlinear coherent state with intensity dependent under the condition of detuning was researched. We found that the initial phase of atom, the parameters of nonlinear coherent state and detuning are all have great influence on the fidelity of systems, and summarized the way of get high fidelity.