Fundamental aspects of Aharonov-Bohm quantum machines: Thermoelectric heatengines and diodes.

Abstract

The study of heat-to-work conversion has gained considerable attention in recent years, highlighting the potential of nanoscale systems to achieve energy conversion in steady-state devices without the involvement of macroscopic moving parts. The operation of these devices is predicated on the steady-state flows of quantum particles, including electrons, photons, and phonons. This review examines the theoretical frameworks governing these steady-state flows within various mesoscopic or nanoscale devices, such as thermoelectric heat engines, particularly in the context of quantum dot Aharonov-Bohm interferometric configurations. Naturally, quantum interference effects hold great promise for enhancing the thermoelectric transport properties of these quantum devices by allowing more precise control over energy levels and transport pathways, thus improving heat-to-work conversion. Driven quantum dot Aharonov-Bohm networks offer an ideal platform for studying these engines, thanks to their ability to maintain quantum coherence and provide precise experimental control. Unlike bulk systems, nanoscale systems such as quantum dots reveal distinct quantum interference phenomena, including sharp features in transmission spectra and Fano resonances. This review highlights the distinction between optimization methods that produce boxcar functions and coherent control methods that result in complex interference patterns. This review reveals that the effective design of thermoelectric heat engines requires careful tailoring of quantum interference and the magnetic field-induced effects to enhance performance. In addition, We focus on the fundamental questions about the bounds of these thermoelectric machines. Particular emphasis is given to how magnetic fields can change the bounds of power or efficiency and the relationship between quantum theories of transport and the laws of thermodynamics. These machines with broken time-reversal symmetry provides insights into directional dependencies and asymmetries in quantum transport. We offer a thorough overview of past and current research on quantum thermoelectric heat engines using the Aharonov-Bohm effect and present a detailed review of three-terminal Aharonov-Bohm heat engines, where broken time-reversal symmetry can induce a coherent diode effect. Our review also covers bounds on power and efficiency in systems with broken time-reversal symmetry. We close the review by presenting open questions, summaries, and conclusions.