FULLY COUPLED MODEL VERSUS ROTATING-WAVE APPROXIMATION IN THE ASYMPTOTIC TIME EVOLUTION OF SPIN SYSTEMS

In the frame of the generalized master equation (GME) approach, an analysis of the asymptotic spin relaxation is made for different j values. The fully coupled (FC) model and the rotating-wave approximation (RWA) for the system-reservoir coupling are considered and it is seen that they give rise to structurally different GMEs. In particular, we examine the evolution of the diagonal and off-diagonal matrix elements of the density operator, the mean values of the relevant observables and the equilibrium solution for both coupling models and display their significant differences. Particularly the spin j = 1 case is examined.