Correlations between charge and heat currents in an interacting quantum dot

TL;DR

This paper investigates how charge and heat currents are correlated in an interacting quantum dot under different voltage and temperature conditions, revealing complex behaviors influenced by Coulomb interactions.

Contribution

It provides a detailed analysis of charge-heat current correlations in a quantum dot with Coulomb interactions using the Hartree approximation, highlighting non-linear and non-monotonous behaviors.

Findings

Heat cross-correlator can change sign, unlike charge cross-correlator.

Coulomb interactions expand the voltage range with negative heat cross-correlations.

Correlators show non-linear voltage dependence and non-monotonous temperature effects.

Abstract

We consider an interacting quantum dot connected to two reservoirs driven at distinct voltage/temperature and we study the correlations between charge and heat currents first as a function of the applied voltage bias, and second as a function of the temperature gradient between the two reservoirs. The Coulomb interactions in the quantum dot are treated using the Hartree approximation and the dot occupation number is determined self-consistently. The correlators exhibit structures in their voltage dependency which are highly non-linear when the coupling between the dot and the reservoirs is weak, and their behavior with temperature is non-monotonous. Moreover the sign of heat cross-correlator can change contrary to what happens with the charge cross-correlator which is always negative. The presence of Coulomb interactions enlarges the domain of voltage in which the heat cross-correlator is negative.