We discuss a model of a unitary evolution of two-qubits where the joint Hamiltonian is so chosen that one of the qubits acts as a bath and thermalizes the other qubit which is acting as the system. The corresponding master equation for the system, for a specific choice of parameters, takes the Gorini-Kossakowski-Lindblad-Sudarshan (GKLS) form with constant coefficients representing pumping and damping of a single qubit system. Based on this model we construct an Otto cycle connected to a single qubit bath and study its thermodynamic properties. Our analysis goes beyond the conventional weak coupling scenario and illustrates the effects of finite bath including non-Markovianity. We find closed form expressions for efficiency (coefficient of performance), power (cooling power) for heat engine regime (refrigerator regime) for different modifications of the joint Hamiltonian.
Nobel Prize in Physics 2022 awarded to Alain Aspect, John Clauser and Anton Zeilinger!