Nonlinear regime for enhanced performance of an Aharonov–Bohm heat engine

Géraldine Haack,Francesco Giazotto

doi:10.1116/5.0064936

Abstract

Thermal transport and quantum thermodynamics at the nanoscale are nowadays garnering increasing attention, in particular, in the context of quantum technologies. Experiments relevant for quantum technology are expected to be performed in the nonlinear regime. In this work, we build on previous results derived in the linear response regime for the performance of an Aharonov–Bohm (AB) interferometer operated as a heat engine. In the nonlinear regime, we demonstrate the tunability, large efficiency, and thermopower that this mesoscopic quantum machine can achieve, confirming the exciting perspectives that this AB ring offers for developing efficient thermal machines in the fully quantum regime.

Highlights

Electrons traveling through the ring acquire two fundamentally different phase factors
We focus on two key parameters, the external gate voltage Vg and the magnetic flux UAB, and fix the other parameters based on Ref. 13
We have analyzed a coherent mesoscopic heat engine consisting of an Aharonov–Bohm quantum interferometer operated in the full nonlinear regime

Summary

AB THERMOELECTRICITY IN THE NONLINEAR REGIME

We start with the thermoelectric properties of the AB ring in an open-circuit configuration. It can already be seen that the external voltage Vg provides an important tunability for controlling Vth. To further explore the thermoelectric response of the AB ring in the nonlinear regime, we show in Fig. 3 the thermovoltage as a function of the gate voltage and magnetic flux [panel (a)], and as a function of the temperature bias [panel (b) as a function of Th, Tc being fixed]. The differential Seebeck coefficient can be two orders of magnitude larger than the one in the linear response regime: the maximum of the blue curve reaches 15 mV/K, whereas the maximum attainable in the linear response regime was of the order of 300 lV/K.13 This confirms the excellent thermoelectric response of this phase-coherent mesoscopic device and motivates the rest of this contribution where we investigate its behavior as a quantum heat engine in a closed-circuit configuration The differential Seebeck coefficient can be two orders of magnitude larger than the one in the linear response regime: the maximum of the blue curve reaches 15 mV/K, whereas the maximum attainable in the linear response regime was of the order of 300 lV/K.13 This confirms the excellent thermoelectric response of this phase-coherent mesoscopic device and motivates the rest of this contribution where we investigate its behavior as a quantum heat engine in a closed-circuit configuration

AB THERMOELECTRICITY IN A CLOSED-CIRCUIT CONFIGURATION

POWER AND EFFICIENCY OF THE AB HEAT ENGINE IN THE NONLINEAR RESPONSE REGIME

CONCLUSIONS AND PERSPECTIVES

E À l0 hvd k2ðEÞ