Dynamic phases of synthetic bath at negative temperatures

Quantum thermal devices are typically designed to perform work beyond classical ability, with their potential to utilize quantum coherence as a resource. Here, we investigate that an energy-carrying molecular model for donor and acceptor coupling to two physical baths and an external driving field offers diverse functions transformed among heat engine, refrigerator, and thermal accelerator. The counter-rotating component of the driving field can induce behavior where the heat flows from the cold bath to the hot one and an output work is done. It is, thus, evident that the precise modulation of the synthetic bath whose inverse temperature varies continuously from negative to positive enables all modes of energy transfer in the phase diagram. The non-equilibrium quantum thermodynamics for realistic devices is further investigated when the external driving field is switched on and off periodically.