Efficient and tunable Aharonov-Bohm quantum heat engine

We propose a quantum heat engine based on an Aharonov-Bohm interferometer in a two-terminal geometry and investigate its thermoelectric performances in the linear response regime. Sizeable thermopower (up to ~0.3mV/K) as well as ZT values largely exceeding unity can be achieved by simply adjusting parameters of the setup and temperature bias across the interferometer, leading to thermal efficiency at maximum power approaching 30% of the Carnot limit. This is close to the optimal efficiency at maximum power achievable for a two-terminal heat engine. Changing the magnetic flux, the asymmetry of the structure, a side-gate bias voltage through a capacitively coupled electrode, and the transmission of the T junctions connecting the AB ring to the contacts allows us to finely tune the operation of the quantum heat engine. The exploration of the parameters' space demonstrates that the high performances of the Aharonov-Bohm two-terminal device as a quantum heat engine are stable over a wide range of temperatures and length imbalances, promising for experimental realization.