Current noise in quantum dot thermoelectric engines

TL;DR

This paper presents a theoretical analysis of a quantum dot thermoelectric engine, emphasizing the importance of next-to-leading order tunneling effects on performance and fluctuations, and exploring quantum advantages over classical bounds.

Contribution

It introduces a detailed theoretical framework including strong interactions and next-to-leading order tunneling, revealing their impact on efficiency and noise in quantum dot engines.

Findings

Next-to-leading order tunneling significantly affects efficiency and noise characteristics.

Quantum effects can potentially violate thermodynamic uncertainty relations, indicating quantum advantage.

For the studied heat engine, quantum effects do not violate but reinforce the bounds set by thermodynamic uncertainty relations.

Abstract

We theoretically investigate a thermoelectric heat engine based on a single-level quantum dot, calculating average quantities such as current, heat current, output power, and efficiency, as well as fluctuations (noise). Our theory is based on a diagrammatic expansion of the memory kernel together with counting statistics, and we investigate the effects of strong interactions and next-to-leading order tunneling. Accounting for next-to-leading order tunneling is crucial for a correct description when operating at high power and high efficiency, and in particular affect the qualitative behavior of the Fano factor and efficiency. We compare our results with the so-called thermodynamic uncertainty relations, which provide a lower bound on the fluctuations for a given efficiency. In principle, the conventional thermodynamic uncertainty relations can be violated by the non-Markovian quantum effects originating from next-to-leading order tunneling, providing a type of quantum advantage. However, for the specific heat engine realization we consider here, we find that next-to-leading order tunneling does not lead to such violations, but in fact always pushes the results further away from the bound set by the thermodynamic uncertainty relations.