Accurate heat currents via reorganized master equation.

Abstract

The accurate characterization of energy exchanges between nanoscale quantum systems and their environments is of paramount importance for quantum technologies, and central to quantum thermodynamics. Here, we show that, in order to accurately approximate steady-state heat currents via perturbative master equations, the coupling-induced reorganization correction to the system's energy must be carefully taken into account. Not doing so may yield sizable errors, especially at low or even moderate temperatures. In particular, we show how a "reorganized master equation" can produce very accurate estimates for the heat currents when the reorganization energy is weak and one works with environments with a broad spectrum. Notably, such master equation outperforms its "nonreorganized" counterpart in the calculation of heat currents, at modeling dynamics, and at correctly capturing equilibration. This is so even if both types of equation are derived to the same order of perturbation theory. Most importantly, working with reorganized master equations does not involve additional complications when compared with alternative approaches. Also, invoking the secular approximation to secure thermodynamic consistency does not compromise their precision.