| The quantum entanglement properties concerned with the interactionbetween atom and optical field in a system has been a very important contentto study in the field of quantum optics. In actual problem, the couplingcoefficient of atom and field is possibly variational. It is valuable inconsidering the entangled properties of moving atom and cavity field. Usingthe negative entropy method, it is mainly discussed that the quantumproperties in a system interacting moving atom with several light-fields. Themain content of this thesis are as follows:In chapter one, the negative entropy method on quantum entanglementand several spread J-C models is introduced, the concepts of the binomialstate light-field and the coherent optical field are explained.In chapter two, the quantum entanglement character of the system in J-Cmodel with multi-photon Gaussian coupling is studied. The influences of theatomic initial state, the atomic motion, the detuning, the average photonnumber of the light field and the transition photon number on theentanglement character of the system are discussed. The results show that thevalue of the entanglement degree of the system changes in the form ofoscillation-stability-oscillation when the atomic motion are considered. Theatomic initial state affects the entanglement degree of the system. When theatomic initial state tends to pure state, the entanglement degree of the systemis larger relatively. With the increase of the average photon number, the valueof the entanglement degree of the system becomes smaller, but the period forthe stable value in the time domain is almost unchanged. Increasing thetransition photon number, the value of the entanglement degree of the systembecomes larger, the period for the stable value in the time domain becomesshorter. As the detuning value increases, the entanglement is disappearinggradually. In chapter three, the quantum entanglement character of the system ofthe binomial optical field interacting with the moving atom is studied. Theinfluences of the atomic initial state, the field-mode structure parameter, themaximum photon number of the binomial field, the coefficient of thebinomial field, the transition photon number and the detuning are discussed.The results show that the value of the entanglement degree of the systemappears regular evolution and ESD phenomenon when the atomic motion isconsidered. The increasing of the field-mode structure parameter shortens theperiod of the entanglement and results in a slight decreasing of the amplitude.The atomic initial state affects the entanglement degree of the system. Whenthe atomic initial state tends to pure state, the entanglement degree of thesystem is larger relatively. With the increase of the maximum photon numberof the binomial field, the value of the entanglement degree of the systembecomes small, but the period for the regular evolution is almost unchanged.When the field is in the middle states, the entanglement degree is smallerrelatively. With the increase of the transition photon number, the value of theentanglement degree of the system becomes larger, the period of theoscillation becomes shorter, meanwhile the oscillation of the system becomesfaster and faster. With the detuning increasing, the entanglement becomessmall.In chapter four, the quantum entanglement character of the system of thecoherent optical field interacting with the moving atom is studied. Theinfluences of the atomic initial state, the field-mode structure parameter, theaverage photon number of the coherent field, the detuning, and the transitionphoton number on the entanglement character of the system are discussed.The results show that the value of the entanglement degree of the systemappears regular evolution and ESD phenomenon when the atomic motion isconsidered. When the atomic initial state tends to pure state, the entanglementdegree of the system is larger relatively. With the increase of the averagephoton number of the coherent field, the value of the entanglement degree ofthe system becomes small, but the period for the regular evolution is almost unchanged. With the increase of the transition photon number, the value of theentanglement degree of the system becomes larger, the period of theoscillation becomes shorter, meanwhile the oscillation of the system becomesfaster and faster. With the detuning increasing, the entanglement becomessmall. |
