Monte Carlo wave function (MCWF) approach to dissipative quantum systems interacting with a single-mode quantized field

We investigate the quantum dynamics of a dissipative molecular system interacting with a single-mode coherent field (with an initial average photon number 8) using the Monte Carlo wave function (MCWF) method. As quantum dissipation, we consider cavity relaxation (the dissipation of an internal single mode to outer mode) and molecular population relaxation and molecular coherent (phase) relaxation caused by nuclear vibration. In this study, we elucidate the effects of these dissipations on the unique quantum dynamic behaviors of this coupled system, e.g., collapse-revival behavior of Rabi oscillations, using the diagonal and off-diagonal molecular density matrices. It is found that although slight cavity relaxation suppresses the revival of molecular population similarly to other relaxation effects with larger decay rates the cavity relaxation hardly suppresses the increase in the off-diagonal molecular density matrix (representing the degree of coherency between the ground and excited states) in the quiescent region, the feature of which is related to the generation of the Schrodinger cat state, in contrast to molecular phase and population relaxations. (C) 2003 Wiley Periodicals, Inc.