Charge fluctuations in nonlinear heat transport

TL;DR

This paper demonstrates that charge fluctuations significantly influence nonlinear heat conductance in interacting nanostructures, revealing new energy-transport resonances and challenging traditional virtual occupation assumptions.

Contribution

It introduces the importance of charge fluctuations in nonlinear heat transport and highlights the limitations of virtual occupation models in describing heat conductance.

Findings

Charge fluctuations are crucial for nonlinear heat conductance.

Energy-transport resonances occur in the Coulomb blockade regime.

Negative differential heat conductance can be observed.

Abstract

We show that charge fluctuation processes are crucial for the nonlinear heat conductance through an interacting nanostructure, even far from a resonance. We illustrate this for an Anderson quantum dot accounting for the first two leading orders of the tunneling in a master equation. The often made assumption that off-resonant transport proceeds entirely by virtual occupation of charge states, underlying exchange-scattering models, can fail dramatically for heat transport. The identified energy-transport resonances in the Coulomb blockade regime provide new qualitative information about relaxation processes, for instance by strong negative differential heat conductance relative to the heat current. These can go unnoticed in the charge current, making nonlinear heat-transport spectroscopy with energy-level control a promising experimental tool.