Preparation And Study Of Quantum Entangled States

Quantum information is a new subject, which is the combination of quantum mechanics and information science. Compared with classical information, quantum information has shown some distinguished advantages. If quantum computation and communication can be realized, there will be a profound revolution in information technology. Nowadays, some flourishing progress about quantum information has been obtained in both theory and experiment.Quantum entanglement is an extraordinary phenomenon, which only belongs to quantum mechanics. Entangled states are not only used to testify some basic quantum theories, but also used as a kind of efficient resource in quantum teleportation, quantum dense coding, quantum cryptography, and so on. We can think that the quantum entangled states have been involved in almost every part of quantum information, and play an important role in quantum information. So, how to prepare entangled states becomes a very important study.In this thesis we will discuss some aspects as follows:1: We will first introduce how the entangled state was put forward, and give the definition and some distinctive qualities of entangled state. Then, we prove the non-localization of quantum mechanics in detail based on Bell's theorem.2: Many existing different theory schemes for preparation of entangled states and some progress in experiment will be shown. We discuss a series of cavity quantum electrodynamics schemes for preparing entangled states emphatically. There are two cases of interaction between atom and cavity mode: resonance and large detuning. Last, we present a new scheme to prepare multi-cavity fields Schrodinger cat state.3: We will show how entangled states are used in quantum information. First, we introduce the basic idea of quantum dense coding, quantum cryptography and quantum teleportation. Then, we introduce a scheme for teleportation of an unknownquantum state without the Bell-state measurement via cavity quantum electrodynamics.