The nonadiabatic entropy production is a useful tool for the thermodynamic analysis of continuously dissipating, nonequilibrium steady states. For open quantum systems, two seemingly distinct definitions for the nonadiabatic entropy production have appeared in the literature, one based on the quantum relative entropy and the other based on quantum trajectories. We show that these two formulations are equivalent. Furthermore, this equivalence leads us to a proof of the monotonicity of the quantum relative entropy under a special class of completely-positive, trace-preserving quantum maps, which circumvents difficulties associated with the noncommuntative structure of operators.Keywords Quantum nonequilibrium thermodynamics · Nonadiabatic entropy production · Quantum relative entropy monotonicity
IntroductionA diversity of physical systems are prevented from relaxing to thermodynamic equilibrium by nonconservative forces or nonequilibrium boundary conditions. Instead, they are maintained in a nonequilibrium steady state characterized by continuously dissipating currents [1,2,3]. As thermodynamic systems, the second law of thermodynamics requires their entropy production rate to always be positive,Ṡ tot ≥ 0. Unfortunately, this inequality is uninformative for driven transitions between distinct nonequilibrium steady states,