Dynamics of thermal entanglement of anisotropically coupled two-qubit system in a time-dependent magnetic field

We investigate the dynamics of entanglement; of a two-qubit system coupled through anisotropic XYZ Heisenberg interaction at finite temperature in the presence of a time-dependent non-homogeneous magnetic field. We find that; for an isotropic coupling and homogeneous magnetic field the thermal entanglement decreases monotonically with both temperature and mean magnetic field amplitude at all times and its time evolution is quite slow. For a non-homogeneous field or anisotropic coupling the entanglement shows an oscillatory behavior in time. The amplitude of the oscillation decreases with temperature but increases with the non-homogeneity of the field. As a function of temperature the entanglement shows revival phenomena. at all times for anisotropic coupling and a small non-homogeneity in the field. As the degree of non-homogeneity increases the revival phenomena disappear. The anisotropy leads to an oscillation in entanglement as a function of the magnetic field amplitude at all times. The entanglement oscillation despite its decaying amplitude sustains for very large values of the magnetic field which becomes even much larger as the non-homogeneity increases. The frequency of the oscillation increases rapidly as we increase the non-homogeneity of the magnetic field and also as time passes.