Heat transport in a two-level system driven by a time-dependent temperature

TL;DR

This paper explores a quantum two-level system acting as a thermal diode driven by a periodically modulated temperature difference, advancing the design of non-linear thermal components for thermotronic circuits.

Contribution

It introduces a non-equilibrium Green's function method extended to time domain for analyzing time-dependent thermal transport in a quantum system.

Findings

The qubit functions as a thermal diode and capacitor.

Capacitance is tunable via reservoir coupling.

Potential for designing advanced thermal circuits.

Abstract

The field of thermotronics aims to develop thermal circuits that operate with temperature biases and heat currents just as how electronic circuits are based on voltages and electric currents. Here, we investigate a thermal half-wave rectifier based on a quantum two-level system (a qubit) that is driven by a periodically modulated temperature difference across it. To this end, we present a non-equilibrium Green's function technique, which we extend to the time domain to account for the time-dependent temperature in one of two thermal reservoirs connected to the qubit. We find that the qubit acts a thermal diode in parallel with a thermal capacitor, whose capacitance is controlled by the coupling to the reservoirs. These findings are important for the efforts to design non-linear thermal components such as heat rectifiers and multipliers that operate with more than one diode.