Study On The Properties Of Quantum Information Dynamics Within Atoms-Cavities-fields System

In this thesis, the present situation of cavity quantum electrodynamics in the field of quantum information has been analyzed, and the conclusions, in the theory and experiments on the preparing the quantum states by using the atoms interacting with cavity fields, is summarized. According to the basic principle of cavity quantum electrodynamics and the peculiarity of the atoms and cavities, a model of multi-atoms and cavities has been proposed and the physical process transmitting quantum information in the system is studied and some new physical phenomena have been discovered and discussed.Following is the main achievements:1 , A novel way of transmitting quantum information has been discovered in a multi-cavity-atom physical system. In this system, atoms can pick up the quantum information stored in the state of the cavity field and carry it out of the cavities in which there is a quantumstate that consists of the lowest two Fock states | 0) and |1) arbitrarily when the atoms, whichall are initially in ground states, cross the cavities with a controlled speed. On the other hand, the atoms can release the quantum information into the cavities when the atoms are in the state thatconsists of the ground states | g) and excited | e) arbitrarily and after the atoms cross thecavities. By this means, one can realize the information exchange between cavities and atoms. We also discussed the information transfer between two sets of cavities through the atomic macroscopic motion and the twice passage of the cavities.2, From the viewpoint of quantum information theory, a multi-atom and multi-cavity system, the interaction between the atoms and the fields in the cavities is described by the intensity dependent coupling J-C model, was investigated. It has been discovered that the atomic maximal entangled state can be transformed into the maximal odd-even-like coherent entangled state, whereas the maximal odd-even-like coherent entangled state can be transformed into the atomic maximal entangled state. The swapping between the continuous and discrete variable entangled states has been realized.3, A physical process, in which one bit or many bits cavity-field states are teleported, is studied. The cavity-field state consists of vacuum and a photon, including disentangled pure and entangled state. In this section, a key technologic, the multi-atom beams distributed detection method by resonant atom-cavity interaction when atoms cross the cavities, is presented to readout the cavity-field Bell states via measuring the atomic states and also needs using an atom crosses the two cavities by non-resonant atom-cavity interaction in order to realize a non-demolition measurement in advance.4, According to the theory of multi-mode squeezed states in references 10-13, we had studied in detail the sum-squeezing effects of the fields in the system of two-mode non-correlated coherent state light field interacted with the V-type three-level atom in the higher-Q Kerr medium cavity. The result indicates that, Sum-squeezing effects depend intensely on the Kerr nonlinear coefficients (x) and the average number of photons and when x<1,...