Abstract
We analyze the noise properties of both electric charge and heat currents as well as their correlations in a quantum-dot based thermoelectric engine. The engine is a three-terminal conductor with crossed heat and charge flows where heat fluctuations can be monitored by a charge detector. We investigate the mutual influence of charge and heat dynamics and how it is manifested in the current and noise properties. In the presence of energy-dependent tunneling, operating conditions are discussed where a charge current can be generated by heat conversion. In addition, heat can be pumped into the hot source by driving a charge current in the coupled conductor. An optimal configuration is found for structures in which the energy dependence of tunneling maximizes asymmetric transmission with maximal charge–heat cross-correlations. Remarkably, at a voltage that stalls the heat engine we find that in the optimal case the non-equilibrium state is maintained by fluctuations in the heat and charge currents only.
Highlights
Thermoelectric effects have been a subject in the physics of mesoscopic conductors almost since the beginning of the field, both experimentally [1, 2] and theoretically [3, 4, 5]
We have investigated the noise and cross-correlations of charge and heat currents in a quantum-dot energy harvester which can be measured by a charge detector
We demonstrated that finite equilibrium cross-correlations are related to the charge current generated by conversion of heat flow between conductors held at different temperatures [21, 22, 23] and rely on the energy-dependent asymmetry of the tunnel couplings
Summary
Thermoelectric effects have been a subject in the physics of mesoscopic conductors almost since the beginning of the field, both experimentally [1, 2] and theoretically [3, 4, 5]. Recent proposals include models for heat transfer mediated by electron-electron interaction [21, 22, 23, 24], electron-boson coupling [25, 26, 27], an electromagnetic environment [28], or a generic heat source [29, 30, 31, 32] In such geometries, a finite electronic current is generated between the two terminals of an unbiased conductor by correlating the transfer of charge and the absorption of energy from the hot source. The heat and charge current statistics become identical Applied to thermoelectrics, such configurations are useful for achieving a tight energy-matter coupling, I ∝ J, which is required for Carnot efficient converters in two- [19, 55] and three-terminal [21]. The fluctuations of heat carried by electrons have been investigated in two terminal conductors [56, 57, 58] and single particle sources [59]
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