Violation of Onsager's theorem in approximate master equation approaches

TL;DR

This paper investigates the failure of common approximate master equations to satisfy Onsager's theorem in thermoelectric transport, revealing deviations that scale with lead-coupling strength in double quantum dot systems.

Contribution

It demonstrates that perturbative approaches like Redfield and second-order von Neumann master equations violate Onsager's theorem in modeling quantum transport.

Findings

Violations of Onsager's theorem scale with lead-coupling strength.

Perturbative approaches fail to maintain thermodynamic consistency.

Deviations occur beyond the systematic order of the approaches.

Abstract

The consistency with Onsager's theorem is examined for commonly used perturbative approaches, such as the Redfield and second-order von Neumann master equations, for thermoelectric transport through nanostructures. We study a double quantum dot, which requires coherences between states for a correct description, and we find that these perturbative approaches violate Onsager's theorem. We show that the deviations from the theorem scale with the lead-coupling strength in an order beyond the one considered systematically in the respective approach.