Quantum correlations and thermodynamic performances of two-qubit engines with local and common baths

Abstract

We investigate heat engines whose working substance is made of two coupled qubits performing a generalized Otto cycle by varying their applied magnetic field or their interaction strength during the compression and expansion strokes. During the heating and cooling strokes, the two qubits are coupled to local and common environments that are not necessarily at equilibrium. We find instances of quantum engines coupled to nonequilibrium common environments exhibiting nontrivial connections to quantum correlations as witnessed by a monotonic dependence of the work produced on quantum discord and entanglement.