Studies On Dynamics Evolution Of Quantum Discord In Heisenberg Model

With the development of quantum theory, quantum correlations are one of the most striking feature in quantum mechanics, which have been paid more attention and studied extensively by people. Quantum correlations are widely used in the field of quantum information science, such as quantum coding, quantum key distribution and quantum teleportation, etc. And they play a non-negligible role in quantum communication and information processing. In this paper we study on dynamics evolution of quantum correlations. There are two important conclusions as follow:First, We investigate on quantum correlations in Heisenberg XXZ model under different magnetic field conditions acting on two qubits:(ⅰ) In the presence and absence of an external magnetic field, quantum discord cannot vanish when there is no quantum entanglement at a finite temperature T. This suggests that quantum discord is more stronger than quantum entanglement under the decoherence environment,(ⅱ) In the case of a magnetic field, we can conclude that nonuniform magnetic field is more beneficial for both quantum entanglement and quantum discord than uniform magnetic field,(ⅲ) For the spin-spin coupling constant.J2the quantum discord can detect quantum phase transition while the entanglement cannot regardless of external magnetic fields appears or disappears.Second, we investigate on dynamics evolution of quantum correlations considering two-qubit in Heisenberg XY model with the Dzyaloshinskii—Moriya (DM) interaction under Markovian environment. In this model, we mainly discuss three types of decoherence environment:ⅰ) a dissipative environment;ⅱ) the infinite temperature or noisy environment; ⅲ) a dephasing environment. There are two results about such three environment:(ⅰ) There is a critical value of DM interaction for which quantum entanglement while quantum discord and classical correlation remain non-zero when considering without decoherence.(ⅱ) In the case of decoherence, that is, considering the external environment, the dynamics of various correlations are different, mainly depends on the types of the interaction of system and environment.