Study On The Dynamics Of Multi-Atom In Coupled-Cavities

The system of coupled cavities is an effective system in studying the interaction between atoms and photons and has received much attention recently. Quantum-state manipulation has been a hot spot in research for a long time. Quantum computation, quantum communication and quantum cryptography are strongly relative to manipulation of quantum states. The shift from theoretical to experimental works needs to go through a long process because of the variation of parameters and effects of noise. Thus it is necessary to research quantum systems coupled to an environment. We study the dissipative dynamics of atoms and photons in a coupled cavity and protect the transformation from cavity decay and atomic spontaneous emission. It can be exploited for reducing the difficulty of the experiment. This dissertation investigates the process of dissipative dynamics between two-level atoms and coupled cavities.Firstly, the system with a high quality cavity coupled to a strong dissipative cavity which consists of two two-level atoms is analyzed. By using the approximate method and the condition of strong dissipation, we simplify the calculations and obtain the required resonance condition of dynamic evolution. By means of numerical simulation, the relationship between parameters and the quantum state transfer is also explored. Based on the mechanism, two-atom entanglement can be generated. We produce and control the quantum state in open systems beneficial to the future research.Secondly, three-cavity systems are analyzed based on the master equation. For ring cavities, the periodical quantum state transfer between two cavities plays dominant roles, because the direct effect is stronger than the indirect effect. In order to investigate the anti-interference ability of the coupled quantum system, we compared the strong dissipative process with the weak one. We also get the result of coupling coefficient influencing cycle. For linetype cavities, an advisable modification of our parameters allows the strong correlation of the separated cavities. Thus the system might open up a promising perspective for realizing long-distance quantum communications.Finally, we discuss the dynamics of the coupled quantum system consisting of ensemble of N two-level atoms. From previous studies, the Dicke model and the Holstein-Primakoff(HP) transformation have been used to resolve atomic ensemble. On this basis, we describe quantum states completely by Fock state and Wigner distribution function and achieve the transfer between atoms and cavity. In addition, two-mode squeezed coherent state are obtained in this system. The results show that our antiinterference method can be applied in coupled quantum system with an atomic ensemble.