Correlations of heat and charge currents in quantum-dot thermoelectric engines

TL;DR

This paper investigates the noise and correlation properties of heat and charge currents in a quantum-dot thermoelectric engine, revealing optimal conditions for energy conversion and the role of fluctuations in maintaining non-equilibrium states.

Contribution

It introduces an analysis of heat-charge current correlations in a quantum-dot thermoelectric engine, highlighting optimal tunneling configurations and fluctuation-driven non-equilibrium states.

Findings

Maximal charge-heat cross-correlations occur at specific tunneling conditions.

Heat can be pumped into the hot source by a driven charge current.

At the stall voltage, fluctuations sustain the non-equilibrium state.

Abstract

We analyze the noise properties of both electric charge and heat currents as well as their correlations in a quantum-dot based thermoelectric engine. The engine is a three-terminal conductor with crossed heat and charge flows where heat fluctuations can be monitored by a charge detector. We investigate the mutual influence of charge and heat dynamics and how it is manifested in the current and noise properties. In the presence of energy-dependent tunneling, operating conditions are discussed where a charge current can be generated by heat conversion. In addition, heat can be pumped into the hot source by driving a charge current in the coupled conductor. An optimal configuration is found for structures in which the energy dependence of tunneling maximizes asymmetric transmission with maximal charge-heat cross-correlations. Remarkably, at a voltage that stalls the heat engine we find that in the optimal case the non-equilibrium state is maintained by fluctuations in the heat and charge current only.