Non-local heat harvesting, refrigeration and thermometry based on triple quantum dot systems

Optimal non-local heat engines, refrigeration engines and thermometers based on dual quantum dots demand a sharp step-like transition in the energy-resolved system-to-reservoir coupling around the quantum dot ground states. Such an abrupt step-like change in the system-to-reservoir coupling cannot be achieved practically. Here, I discuss a realistic design for non-local heat engine, refrigeration engine and thermometer based on triple quantum dot set-up, that circumvents the necessity for any change in the system-to-reservoir coupling, demanded by the optimal dual dot setups. Proceeding further, I discuss the the performance of the triple dot set-up and point out that the set-up, when employed as heat and refrigeration engine, delivers approximately 50~70% performance of that of the optimal dual dot set-up. However, the triple dot thermometer surpasses the performance of the dual dot thermometer by a significant margin, in addition to sppressing thermometry induced drift in the target reservoir temperature. The novelty of the discussed triple dot set-up lies in fabrication simplicity along with reasonable performance, making it suitable for practical deployment as non-local heat engine, refrigeration engine and thermometer.