A realistic non-local heat engine based on Coulomb-coupled systems

Abstract

Optimal non-local heat engines based on Coulomb-coupled systems demand a sharp step-like change in the energy-resolved system-to-reservoir coupling around the ground state of quantum dots. Such a sharp step-like transition in the system-to-reservoir coupling cannot be achieved in a realistic scenario. Here, I propose a realistic design for a non-local heat engine based on the Coulomb-coupled system, which circumvents the need for any change in the system-to-reservoir coupling, demanded by the optimal setups discussed in the literature. I demonstrate that an intentionally introduced asymmetry (or energy difference) in the ground state configuration between adjacent tunnel-coupled quantum dots, in conjugation with Coulomb coupling, is sufficient to convert the stochastic fluctuations from a non-local heat source into a directed flow of thermoelectric current. The performance, along with the regime of operation, of the proposed heat engine is then theoretically investigated using the quantum master-equation approach. It is demonstrated that the theoretical maximum power output for the proposed setup is limited to about 50% of the optimal design. Despite a lower performance compared to the optimal setup, the novelty of the proposed design lies in the conjunction of fabrication simplicity along with a reasonable power output. At the end, the sequential transport processes leading to a performance deterioration of the proposed setup are analyzed and a method to alleviate such transport processes is discussed. The setup proposed in this paper can be used to design and fabricate high-performance non-local cryogenic heat engines.