We investigate, in detail, a triple quantum dot system that exploits Coulomb coupling to achieve nonlocal refrigeration. The system under investigation is a derivative of the nonlocal thermodynamic engine, originally proposed by Sánchez and Büttiker [Phys. Rev. B 83, 085428 (2011)], that employs quadruple quantum dots to attain efficient nonlocal heat harvesting. Investigating the cooling performance and operating regime using the quantum master equation approach, we point out some crucial aspects of the refrigeration engine. In particular, we demonstrate that the maximum cooling power for the setup is limited to about $70\%$ of the optimal design. Proceeding further, we point out that to achieve a target reservoir temperature lower than the average temperature of the current path, the applied voltage must be greater than a given threshold voltage $V_{\mathrm{TH}}$ that increases with the 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 triple quantum dot system, investigated in this paper, combines fabrication simplicity along with descent cooling power and may pave the way towards the practical realization of efficient nonlocal cryogenic refrigeration systems.

中文翻译：

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基于库仑耦合系统的逼真的非本地制冷引擎

我们将详细研究利用库仑耦合实现非局部制冷的三重量子点系统。所研究的系统是非局部热力学发动机的衍生产品，最初由Sánchez和Büttiker提出。版本B 83，085428（2011）]，即使用四量子点达到有效的非局部热收获。使用量子主方程方法研究制冷性能和运行方式，我们指出了制冷发动机的一些关键方面。特别是，我们证明了该设置的最大冷却功率被限制为大约$70％$最佳设计。进一步，我们指出，要使目标储层温度低于电流路径的平均温度，施加的电压必须大于给定的阈值电压$V_{\mathrm{TH}}$随着目标储层温度的降低而增加。此外，我们证明了最大冷却功率以及性能系数会随着接近较低的目标油箱温度而降低。本文研究的三重量子点系统结合了制造的简便性和下降的冷却能力，可以为有效实现非局部低温制冷系统的实现铺平道路。