The Dynamic Properties Of Quantum Entanglement And Nonlocality In Multipartite Cavity-reservoir Systems

Quantum entanglement is one of the most important physical resources in quantum information processing, which has been widely applied to quantum teleportation, quantum key distribution, quantum dense coding, universal quantum computing, and so on. Nonlocality is a different correlation from entanglement, which plays an important role in quantum secure communication. All the entangled states have the nonlocality, and the two kinds of correlation have deep connections. In the real quantum information processing, the environment around the physical system can lead the quantum entanglement and nonlocality to degrade. The decay of quantum resources induced by environment noise is an important topic in the quantum information processing field. This thesis is focused on the dynamical properties of quantum entanglement and nonlocality in multipartite cavity-reservoir systems. We study the detection of multipartite entanglement in GHZ and W mixed state, and investigate the dynamics of quantum entanglement and measurement-induced nonlocality in bipartite mixed maximally entangled states.The thesis is divided into three parts. In chapter one, we introduce some basic concepts, such as quantum entanglement, entanglement distribution and measurement-induced nonlocality, and so on. In chapter two, we study the detection of multipartite entanglement in GHZ and W mixed states, where two methods based on GHZ symmetry and entanglement monogamy are utilized. We find that the two methods have different merits. The GHZ symmetry method gives a clear entanglement structure, while the monogamy method has a strong detection ability. In chapter three, we first study the negativity and measurementinduced nonlocality of the mixed maximally entangled state in multipartite cavity-reservoir dynamics. It is found that the maximal entanglement cannot guarantee the maximal nonlocality. Along the time evolution, the entanglement of mixed maximal entangled state disappears in a finite time, rather than the asymptotic way like the measurement-induced nonlocality. Furthermore, our numerical analysis shows that the squared negativity is monogamous and the measurement-induced nonlocality is polygamous in the multipartite cavity-reservoir systems. In addition, we give the dynamical evolution of multi-photon states and analyze the dynamics of high dimensional pure maximally entangled state. We show that the high dimensional pure maximally entangled state exhibits the entanglement sudden death phenomenon too.