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.Comment: 13 page