Field Of The Quantum Properties Of Atomic Interaction Process Control Problems

Quantum entanglement is one of the most remarkable characters of quantum mechanics, is also a very important resource in quantum communication. It has important applications in quantum teleportation> quantum dense coding,quantum error-correcting,and quantum computation, Especially the multi-particle entanglement play an important role in the engineering of quantum state.The cavity quantum electrodynamics (cavity QED) can help us to understand non-classical effects and reveal the interaction dynamics of atoms and optical fields. With the experimental developments concerning cavity QED, electrodynamics (QED) technique has been proven to be one of promising candidates for the physical realization of quantum information processing. In this thesis, we focus our research on the long-distance controlling of quantum characteristics for non-local entangled system after the evolution of cavity QED. The main results of this thesis are as follows:1. Firstly, we introduced the concept of quantum entanglement and the relevant knowledge of the biggest entangled state for three particles. We also explained the way of measuring quantum entanglement in partial transposition negative eigenvalue method. Secondly, we introduced non-classical effects of atom behavior interacting with light fields.2. Two-mode fields of two-mode entangled coherent lights are poured into two cavities separately and simultaneously. Two of two-level atoms in three-body entangled state initially, are put in two cavities respectively, interacting separately with two-mode coherent light fields resonantly. After the evolution of cavity QED, photon detection for coherent light fields and selective measurement for atoms are carried out. Through controlling the interaction time and the parameters of two light fields, Non-classical effects of the third atom, of W state outside the cavity, are controlled, such as the collapse-revival phenomenon of atom's occupancy and atomic dipole squeezing phenomenon, thus the stronger long-distance controlling for the non- classical characteristics of the atom can be achieved.3. Considered one of two-level atoms in entangled state interacts with a single mode and double-photon cavity field resonantly. After the evolution of cavity QED, photon detection for cavity field is carried out. Through controlling the interaction time and the parameters of light fields as well as the entanglement degree of two entangled atoms in the initial state, the stronger non-classical effects of the atom outside the cavity are controlled, such as atomic dipole squeezing phenomenon. Simultaneously using the same method, the entanglement evolution between two atoms as the channel of the long-distance controlling is also controlled. Thus controlling of quantum characteristics for two-atom system is achieved effectively. And the relation of entanglement and squeezing is found.