Realistic non-local refrigeration engine based on Coulomb coupled systems

TL;DR

This paper introduces a Coulomb-coupled quantum dot refrigeration system that enables non-local cooling without changing energy-resolved system-reservoir couplings, highlighting its performance limits and operational conditions.

Contribution

It presents a novel non-local refrigeration engine based on Coulomb-coupled quantum dots, simplifying fabrication while maintaining effective cooling performance.

Findings

Maximum cooling power is about 70% of the optimal design.

Achieving lower target reservoir temperatures requires voltages above a threshold V_TH.

Cooling power and efficiency decrease at lower target temperatures.

Abstract

Employing Coulomb-coupled systems, we demonstrate a cryogenic non-local refrigeration engine, that circumvents the need for a change in the energy resolved system-to-reservoir coupling, demanded by the recently proposed non-local refrigerators. We demonstrate that an intentionally introduced energy difference between the ground states of adjacent tunnel coupled quantum dots, associated with Coulomb coupling, is sufficient to extract heat from a remote target reservoir. Investigating the performance and operating regime using quantum-master-equation (QME) approach, we point out to some crucial aspects of the proposed refrigeration engine. In particular, we demonstrate that the maximum cooling power for the proposed set-up is limited to about $70\%$ of the optimal design. Proceeding further, we point out that to achieve a target reservoir temperature, lower compared to the average temperature of the current path, the applied voltage must be greater than a given threshold voltage $V_{TH}$, that increases with decrease in the target reservoir temperature. In addition, we demonstrate that the maximum cooling power, as well as the coefficient of performance deteriorates as one approaches a lower target reservoir temperature. The novelty of the proposed refrigeration engine is the integration of fabrication simplicity along with descent cooling power. The idea proposed in this paper may pave the way towards the realization of efficient non-local cryogenic refrigeration systems.