Quantum control of nonlinear thermoelectricity at the nanoscale

TL;DR

This paper demonstrates how quantum coherence regulation in nanostructures like quantum dots can significantly enhance nonlinear thermoelectric effects, offering new pathways for efficient nanoscale heat engines.

Contribution

It introduces a theoretical framework for controlling nonlinear thermoelectricity via quantum coherence, including analytical models and optimization strategies for quantum-dot heat engines.

Findings

Quantum coherence regulation enhances thermoelectric performance.

Fano resonance can induce thermoelectric enhancement.

Optimal gate voltages improve efficiency and power output.

Abstract

We theoretically study how one can control and enhance nonlinear thermoelectricity by regulating quantum coherence in nanostructures such as a quantum dot system or a single-molecule junction. In nanostructures, the typical temperature scale is much smaller than the resonance width, which largely suppresses thermoelectric effects. Yet we demonstrate one can achieve a reasonably good thermoelectric performance by regulating quantum coherence. Engaging a quantum-dot interferometer (a quantum dot embedded in the ring geometry) as a heat engine, we explore the idea of thermoelectric enhancement induced by the Fano resonance. We develop an analytical treatment of fully nonlinear responses for a dot with or without strong interaction. Based on the microscopic model with the nonequilibrium Green function technique, we show how to enhance efficiency and/or output power as well as where to locate an optimal gate voltage. We also argue how to assess nonlinear thermoelectricity by linear-response quantities.