The Research Of Controlled-NOT Gate And Entanglement Of Interaction Between Atoms And Optical Field

Quantum information science, which mainly includes quantum computer and quantum communication has increasingly evolved as a new object.Because the carrier of. Information in this subject, all the problems related to information should be resolved by means of quantum theory.Therefore; quantum information science exhibits a number of advantages corresponding to classical counterpart. In the past few years, quantum information has made a surprise progress both in theoretical and experimental fields; it has created many miracles, such as absolute secure quantum key, quantum dense coding quantum teleportation, and so on. Quantum communication is an important branch of quantum information science, and mostly involves quantum teleportation, quantum dense coding, quantum secret share, quantum secure communication.The idea of the cavity QED is to trap several atoms in a small high quality optical cavity. Quantum information can again be stored in the internal states of the atoms. The trapped atoms will provide quantum memory and optical cavities will be utilized both to perform quantum gates and to transfer quantum information. With the experimental developments concerning cavity QED, electrodynamics(QED)technique has been proven to be a promising candidate for the physical realization of quantum information processing. In this thesis, we focus our research on the applications of cavity QED to quantum information. The main results of this thesis are as follows:1 Based on the research of Tavis-Cumming model of interaction between light and atom.using the calculating method of concurrence We investigate the entanglement character in a system of two coupling atoms interacting with a single-mode field. The influences of the atomic dipole-dipole and initial state interaction on the degree of the entanglement are discussed.Results of research shows: (1)Through calculating the concurrence entanglement between coupling doubling atoms and single radical field in the T-C Model and analyzing the character of entanglement. We can conclude hat entanglement show periodically oscillating.(2) The atomic initial state affects the oscillating amplitude, but not influence the periodicity of oscillating.(3) By the increasing ofΩ.the oscillating shape shows regulation.2. To implement controlled-NOT gate, We propose a scheme which using system of coupling double atoms interacting with single-mode optical field. Result shows: While cavity field is prepared to be initially in the coherent state and double atoms is in the specially primary state,under the condition of large detuning,we can achieve controlled-NOT gate by controlling the time of interaction of cavity field and double atoms.