Normal metal tunnel junction-based superconducting quantum interference proximity transistor: the N-SQUIPT

TL;DR

This paper introduces a novel N-SQUIPT device that uses a normal metal probe, enabling full modulation of the wire's density of states with minimal power dissipation, suitable for ultra-low power cryogenic applications.

Contribution

The paper presents a new N-SQUIPT design that eliminates Josephson coupling, achieving significant improvements in modulation and power efficiency over previous SQUIPT devices.

Findings

Achieved full modulation of density of states with magnetic field.

Power dissipation as low as 10^{-17} W.

Enhanced sensitivity by up to four orders of magnitude.

Abstract

We report the fabrication and characterization of an alternative design for a superconducting quantum interference proximity transistor (SQUIPT) based on a normal metal (N) probe. The absence of direct Josephson coupling between the proximized metal nanowire and the N probe allows us to observe the full modulation of the wire density of states around zero voltage and current \textit{via} the application of an external magnetic field. This results into a drastic suppression of power dissipation which can be as low as a few $\sim 10^{-17}$ W. In this context the interferometer allows an improvement of up to four orders of magnitude with respect to earlier SQUIPT designs, and makes it ideal for extra-low power cryogenic applications. In addition, the N-SQUIPT has been recently predicted to be the enabling candidate for the implementation of coherent caloritronic devices based on proximity effect.