Abstract
We theoretically investigate the propagation of heat currents in a three-terminal quantum dot engine. Electron–electron interactions introduce state-dependent processes which can be resolved by energy-dependent tunneling rates. We identify the relevant transitions which define the operation of the system as a thermal transistor or a thermal diode. In the former case, thermal-induced charge fluctuations in the gate dot modify the thermal currents in the conductor with suppressed heat injection, resulting in huge amplification factors and the possible gating with arbitrarily low energy cost. In the latter case, enhanced correlations of the state-selective tunneling transitions redistribute heat flows giving high rectification coefficients and the unexpected cooling of one conductor terminal by heating the other one. We propose quantum dot arrays as a possible way to achieve the extreme tunneling asymmetries required for the different operations.
Highlights
The control of heat flows in electronic conductors is one of the present day technological challenges
Besides the conversion of heat currents into electrical power which is the main focus of thermoelectrics, there is the possibility of making all-thermal circuits that work only with heat currents and temperature gradients
The presence of different gaps due to interaction effects (e.g. Coulomb blockade) or superconductor interfaces can be controlled. This possibility has been evident in the last years with the proposal and experimental realization of heat engines [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17] and electronic refrigerators [1, 18,19,20,21,22,23,24] based on nanoscale systems, and with the detection of heat currents [18, 25,26,27,28,29]
Summary
The control of heat flows in electronic conductors is one of the present day technological challenges. In mesoscopic conductors, the dominant interaction can be engineered by introducing additional components which mediate the coupling to the environment, e.g. a quantum point contact [53], quantum dots [11, 12, 54], or photonic cavities [55,56,57] This allows one to define different interfaces for the different operations. We propose a multi-terminal system of two capacitively coupled quantum dots as a versatile configuration for the efficient manipulation of electronic heat currents, as sketched in figure 1. Energy exchange mediated by electrostatic coupling has the additional advantage of allowing for defining thermal insulating system-gate interfaces This way eventual heat currents leaking from the gate to the conductor, e.g. due to phonons, are suppressed.
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