Proximity nanovalve with large phase-tunable thermal conductance

TL;DR

This paper introduces a phase-controlled quantum heat valve using a superconducting proximity effect, enabling precise thermal regulation at sub-Kelvin temperatures for advanced caloritronic applications.

Contribution

It presents a novel proximity nanovalve design based on SQUIPT that achieves large, tunable thermal conductance controlled by magnetic flux.

Findings

Temperature swings exceeding 100 mK achieved.

Flux-to-temperature transfer coefficients up to 500 mK/Φ₀.

Performance improves at lower bath temperatures.

Abstract

We propose a phase-controlled heat-flux quantum valve based on the proximity effect driven by a superconducting quantum interference proximity transistor (SQUIPT). Its operation relies on the phase-dependent quasiparticle density of states in the Josephson weak-link of the SQUIPT which controls thermal transport across the device. In a realistic Al/Cu-based setup the structure can provide efficient control of thermal current inducing temperature swings exceeding $\sim100$~mK, and flux-to-temperature transfer coefficients up to $\sim 500$~mK/$\Phi_0$ below 100~mK. The nanovalve performances improve by lowering the bath temperature, making the proposed structure a promising building-block for the implementation of coherent caloritronic devices operating below 1~K.