Kinetic equations for a quantum dynamical system interacting with a thermal reservoir and a random field

The nonequilibrium density matrix method for quantum systems is used to investigate the relaxation of a dynamical system that interacts with a thermal reservoir and with a random external field. Kinetic equations that describe the evolution of the populations of the states of the dynamical system are obtained. The probabilities of transitions between the states of the system are found as functions of the temperature and the parameters of the random field, which is modeled by a discrete Markov process of telegraph type. Relaxation transitions in a three-level dynamical system are considered as applications.