Lindblad和Redfield方程对自旋链平衡性质的研究

In this paper,we have derived the concrete forms of Lindblad equation and Redfield equation in the spin chain by the method by Prosen et al. Then the average magnetic moment and nearest neighbor correlation functions of one-dimensional homogeneous quantum Ising chain whose two ends are connected with baths with the same tempertuare are numerically simulated. By contrast of analytical results, we find when the system internal is in weak coupling which is to say the external field h is greater than the exchange interaction between the spin J,the calculated results of two equations above are both very close to the analytical result.But when the system internal is in tight coupling which is to say h is close to J, both of results calculated by two equations above have a gap. It is proved that the two eqations are derived through different approximation conditions of kinetic eqation. Moreover,when the temperature is higher,compared with the Lindblad equation, the Redfield equation is more close to the analytical result.