Preparation For Entangled States Of Atoms Via Adiabatic Passage In Coupled Cavity System

Quantum information science, as a subject of leading emerging disciplines in the scientific fields, makes a combination between quantum mechanics and information science and a great breakthrough has been made both in the experiments and theories. As an important resource in quantum information processing, how to prepare the entangled states has been of significance on the development of quantum information. Recently, stimulated Raman adiabatic passage has also become one kind of new technology to prepare entangled states. Many researchers put forward schemes based on combining the entangled states of atoms and stimulated Raman adiabatic passage. This paper focuses on the preparation of entangled states which is based on the adiabatic passage in coupled cavity systems. The main contents are structured as follows:The entangled states and the master equation of quantum systems are introduced in the first chapter. Firstly, we focus on the appearance and definition of the entangled states, and the development of the entangled states, as well as several common entangled states etc. Secondly, we deduce the master equation under the weak coupling approximation, Markov approximation and rotating wave approximation. Finally, we give the conceptions of the fidelity of quantum entangled states.The basic theoretical of the quantum optics are introduced in the second chapter, including the cavity QED and stimulated Raman adiabatic passage (STIRAP). We focus on the introduction of cavity-fiber coupled systems and the coupled cavity systems which have their advantages respectively, and explore the importance of these two systems for large-scale quantum information processing. For stimulated Raman adiabatic passage, we mainly introduce the adiabatic control. We also study the selection of the pulses. It turns out that a perfect evolution can be found if the proper shape of the pulses are selected.In the third chapter, how to generate Greenberger-Horne-Zeilinger states of trapped in spatially separated cavities connected by optical fibers based on stimulated Raman adiabatic process are investigated. We choose the Gaussian shapes of the classical fields appropriately and show the numerical simulation for the preparation of the GHZ states, then analyze the influence of each parameter on the fidelity. The results show that the fidelity is not sensitive to the fluctuations of experimental parameters and the changing of evolution time. And we can obtain the multi-atom GHZ states by increasing the number of cavities.In the forth chapter, the preparation of the entangled states between atoms in the coupled-cavity QED system is studied, which makes use of the adiabatic evolution of the dark state. In this scheme, three four-level atoms are also trapped in three coupled-cavities. Here, we adopt directly coupled-cavity QED system, as a result, the operation is more easily when compared with the cavity-fiber QED system. According to the numerical simulation, we can obtain a high fidelity. By increasing the number of cavities, we find that the multi-atom entangled states can be prepared.Finally, the results are summarized at the end of the paper.