Quantum Entanglement And Nonlocality Of Multiphoton Entangled States

Recently, with the development of quantum mechanics, quantum information theory has become one of the frontest areas in physics and information science. Quantum mechanics is composed of theory foundation of modern physics with relativity. However, Quantum entanglement and quantum non-locality are two profound and peculiar characteristics of quantum mechanics. They are also essential concepts of contemporary quantum information science. Thery are not only theory foundation to realize quantum technology, but also have quite fascination potential applications to quantum information science and technology. So quantum entanglement and quantum nonlocality have become hot topics. Quantum entanglement has played an important role in quantum information theory and been viewed as an essential resource of quantum information processing. It is also a main reason for fundamental differences with classical information. It has been extensively used in quantum information processing and quantum communication. Such as quantum computation, quantum cryptography, quantum dense coding and quantum teleporation etc. Its distinct characteristic is its quantum nonlocality. Quantum entanglement of multi-particle system is a important manner to embody quantum nonlocality. Most of questions in quantum information theory are concerned with quantum entanglement phenomenon.This thesis is devoted to investigating quantum entanglement and quantum nonlocality of multi-phton entangled states: In chaper 2, we introduce the basic theory of quantum entanglement and quantum nonlocality. We describe simply the definition of quantum entanglement and measurement of the degree of quantum entanglement; Involving the definition of quantum nonlocality, EPR paradox and Bell inequalities and their extention. Our tasks are from chaper 3 to 5, In chaper 3, our innovations lie that we investigate the entanglement characters of multi-phton entangled states. We calculate the von Neumann entropy of them and conclude that the von Neumann entropy are changed periodically by entanglement angle for the case of different photon number. And we can see the von Neumann entropy is increased by adding...