Thermodynamics of Minimal Coupling Quantum Heat Engines

The minimal-coupling quantum heat engine is a thermal machine consisting of an explicit energy storage system, heat baths, and a working body, which couples alternatively to subsystems through discrete steps – energy conserving two-body quantum operations. Within this paradigm, it is presented a general framework of quantum thermodynamics, where a process of the work extraction is fundamentally limited by a flow of non-passive energy (ergotropy), while energy dissipation is expressed through a flow of passive energy. The main result is finding the optimal efficiency and work extracted per cycle of the three-stroke engine with the two-level working body. One of key new tools is the introduced “control-marginal state” – one which acts only on a working body Hilbert space but encapsulates all the features of total working body-battery system regarding work extraction.
Link to the paper: https://arxiv.org/abs/2003.05788