A thermal superconducting quantum interference proximity transistor

Ingrid Fadelli is a writer for Phys.org.

Superconductivity is a state in which matter has no electrical resistance and does not allow magnetic fields to be penetrated. Due to the proximity effect, these materials are known to be highly effective thermal insulators and can also influence the density of nearby metallic or superconducting wires.

Researchers at CNR and Scuola Normale Superiore in Italy have recently developed a transistor that takes advantage of this specific quality of superconductors. Their transistor, dubbed a thermal superconducting quantum interference proximity transistor, was introduced in a paper.

The frame of phase-coherent caloritronics is where our work lies, and it aims to envision and realize devices able to master the energy transfer in different quantum technology architectures.

The main idea behind T-SQUIPT is to control the thermal properties of a metal or superconductor through the so-called superconducting proximity effect. The transistor exploits the quantum phase to control the density of states in a metal in the vicinity of a superconductor.

Giazotto said that the T-SQUIPT was first proposed several years ago by some of the authors of the recent paper.

Normal metals can allow electrons in their crystals to transfer heat and charge, which makes them good conductors of both heat and electricity. Superconductors are poor thermal conductors as the main free carriers in their crystals are Cooper pairs. The charged pairs of electrons cannot transfer heat.

The core concept of T-SQUIP is a small island of aluminum that can be made into a metal with quantum interference, and placed in a metallic contact with the island.

Superconductivity is reinforced and the island behaves as a good thermal insulator when the quantum values of the flux quantum pierce the loop. The island behaves as a good thermal conductor if superconductivity is suppressed.

This unique design, first introduced by the researchers in a paper published in 2014, allows them to suppress or reinforce superconductivity in their transistor at will, simply by applying an external magnetic field. A thermal valve is when the aluminum island in the transistor can be fully manipulated.

Giazotto and his colleagues demonstrated this ability of their transistor by sinking heat from a metallic electrode into it, which was also coupled to the aluminum island through a tunnel contact. Their findings show the feasibility of manipulating the energy transport qualities of quantum devices.

Giazotto said that the control of the heat transport opens the way to realize structures where the thermal counterparts of electronic devices, such as thermal transistors, memories, logic gates and thermoelectric engines, are realized.

The T-SQUIPT transistor could pave the way for the realization of a variety of new devices in the future. The paper enhances the current understanding of energy transfer at the nanoscale, which could improve its management.

The recent work by Giazotto and his colleagues could lead to new studies about the quantum thermodynamics in superconductivity. In their next studies, the team at CNR and Scuola Normale Superiore will try to improve the performance of T-SQUIPT by improving the design of the thermal valve and by using superconducting materials.

Giazotto plans to study the time response of the memory cell in order to investigate its ability to retain data over several days.

More information: Nadia Ligato et al, Thermal superconducting quantum interference proximity transistor, Nature Physics (2022). DOI: 10.1038/s41567-022-01578-z

E. Strambini and his co-authors wrote about a proximity nanovalve with large phase-tunable thermal conductance. There is a DOI of 10.1063/1.4893759.

Journal information: Applied Physics Letters , Nature Physics

The Science X Network will be launched in 2022.

Citation: A thermal superconducting quantum interference proximity transistor (2022, May 5) retrieved 5 May 2022 from https://phys.org/news/2022-05-thermal-superconducting-quantum-proximity-transistor.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.