Efficiency and power output of a two-stroke quantum heat engine with a collisional model consisting of N ≤ 5 qubits

Heat engines are thermal devices that convert input energy from a thermal reservoir to generate useful work. However, not all energy is converted into mechanical work—some is discarded into a heat sink, such that the measure of the ratio of work output to heat input is called efficiency. The power of a heat engine characterizes the work-output rate. In the quantum regime, quantum heat engines (QHEs) operate the same way but use quantum matter as a working substance.