Thermal Entanglement And Entanglement Dynamics Of Spin System With Dzialoshinskii-Moriya Interaction

Quantum entanglement is one of the most striking features of quantum mechanics and has been found important not only in studying fundamental problems of quantum mechanics but also holds the key to applications in the implementation of quantum information processing. Based on quantum entanglement, we can realize quantum dense coding, quantum teleportation, quantum cryptography and so on, which cannot be resolved by classical theory. Therefore, it's becoming very important to control quantum entanglement. In order to apply the quantum information processing into the reality, we need the extended and integrated systems. Spin system is such a solid system. In this thesis, we will focus on studying the thermal entanglement and entanglement dynamics of Hesienberg model and Ising model with Dzialoshinskii-Moriya (DM) anisotropic antisymmetric interaction. The main contents of this thesis are given as follows:(1) The effect of DM interaction on entanglement of a two-qubit Ising model in an inhomogeneous magnetic field is investigated. Negativity, the measurement of entanglement, is calculated. The evolvement of entanglement dependences on DM interaction, the homogeneous magnetic field B and the inhomogeneous magnetic field h are discussed.(2) We investigate the entanglement dynamics of two-spin Ising model with the DM interaction in an inhomogeneous magnetic field. By means of concurrence theory, we analyze in detail the effects of the DM interaction, the degree of inhomogeneous magnetic field and the purity of the initial state on the time of ESD (entanglement sudden death).(3) The effect of intrinsic decoherence on entanglement in a two-qubit Heisenberg XXZ with DM interaction is investigated. It is found that the intrinsic decoherence, DM interaction and the homogeneous magnetic field give significant influence to the entanglement by employing the concurrence as entanglement measure. The paper is useful for the deeper study of the influence of DM interaction on thermal entanglement and entanglement dynamics.