Generation Of Entangled Coherent States

A combination of quantum mechanics and information science yields a new subject, namely, quantum information science. Nowadays some flourish progress about quantum information has been obtained in both theory and experiment, meanwhile quantum information has shown some distinguished advantages compared with classical information. Therefore, quantum information will inaugurate a new way for the development of information science. Quantum communication is a very important branch of quantum information. Quantum communication mainly includes preparation of quantum state, quantum teleportation, quantum dense coding, quantum key distribution, and so on. Born as a new cross subject of information science and quantum mechanics, quantum information is undoubtedly a fruitful production of quantum mechanics. Meanwhile, it wildly enriches the research field of quantum mechanics and greatly promotes the development of quantum theory. As a fundamental Physical resource for quantum information Processing quantum entangled states are extensively used in quantum computation and quantum communication,quantum teleportation,quantum dense coding,and so on. In recent years,the preparation of continuous variable entanglement and its application in quantum optics and quantum information are acting on a frontier field. As continuous variable entanglement,entangled coherent states attract more and more attentions of people. In this paper, we present two schemes to generate entangled coherent states, one is to generate Bell-type entangled coherent states and cluster-type entangled coherent states based on cavity QED, the other is to generate such states in free-traveling optical fields. They have their own advantages.The paper is organized as follows: In the first chapter, we make a summary and introduce its research purpose and main contents. In the second chapter, we introduce some knowledge about quantum information. The third and the fourth are the main work we do. In the third chapter, we investigate the scheme to generate Bell-type and cluster-type entangled coherent states based on cavity QED. In the fourth chapter, we propose a protocol for generating cluster-type entangled coherent states in free-traveling optical fields. And in the last chapter, we make some conclusion and foreground.