Thermalization of an Open Quantum System Via Full Diagonalization

Thermalization, the irreversible relaxation of a system to thermodynamic equilibrium, ultimately arises from the reversible dynamics of many-body quantum systems. Weakly coupling a small system to a large many-body quantum system (heat bath) results in the equilibration of the small system to the Boltzmann distribution. We solve numerically, using full diagonalization, a model in which a small system is coupled to a large quantum system, and retrieve the thermodynamic behavior from the underlying quantum mechanics. We discuss the mechanism of thermalization, and the applications of our simulation for exploring the behavior of damped quantum systems.