Simulating infinite baths using finite baths with periodic refreshing

A large part of research in quantum physics, biology, chemistry and engineering revolves around understanding quantum many-body systems connected to multiple baths which can all have different temperatures and chemical potentials. However, a general approach for the numerically exact description of the dynamics of such open quantum many-body systems has remained an outstanding problem. The main difficulty in simulating such set-ups stems from the baths having infinite degrees of freedom. Here we show that it is possible to accurately simulate the dynamics of a wide class of such open quantum many-body systems using finite and rather small-sized baths, when the baths are refreshed to their original initial states periodically after a carefully chosen time interval. This tremendously simplifies obtaining the dynamics of such set-ups, albeit in discrete time steps. When combined with existing tensor network approaches, this provides an extremely efficient and general technique to obtain numerically exact dynamics of a large class of interacting open quantum many-body systems beyond all other state-of-the-art techniques.