Fidelity Of Quantum State In A System Of A Moving Two-level Atom Interacting With Light For Multi-photon Transitional Process

With the application of quantum mechanics in the field of information science, this new interdisciplinary that quantum information science gradually has formed. In the field of quantum information, the quantum state is the carrier of information, the transmission of which must involve the distortion, so the problem of the quantum state fidelity has attracted the attention of a great number of people, and conducted extensive and in-depth research. In his paper, using the full quantum theory, the fidelity of light-field interacting with atomic system is studied from the following aspects:The first chapter introduces the definition of fidelity of quantum state and basic theory of damping Jaynes-Cummings model; two typical optical fields—the Schrodinger cat state light field and Pólya state light field, were also presented.In the second chapter, the fidelity evolution in a system which is composed of a multi-photon transition moving two-level atom interacting with the Schr?dinger cat state is studied. The influences of the strength of light field, the phase angle between the two coherent states, the atomic motion and the number of transition photon on the fidelity in a system are discussed.In the third chapter, the fidelity of quantum state in a system which two atoms interacting with two mode vacuum state light field in a damping Jaynes-Cummings model is studied. The influences of the parameters such as the initial state of atoms, transition frequency, the frequency of the cavity field, dissipative damping parameters on the fidelity of quantum states in the system are analyzed.In the fourth chapter, The fidelity in a system which is composed of a multi-photon transition moving two-level atom interacting with Pólya state light is studied. The influences of the atomic initial state, field-mode structure parameter, the maximum photon number of the light, the optical field parameters and the values of the transitional photon number on the fidelity of the system are also analyzed.