Optimized proximity thermometer for ultra-sensitive detection

TL;DR

This paper develops and tests an optimized proximity-based superconducting thermometer, combining experimental device testing with a theoretical model to enhance ultra-sensitive temperature detection.

Contribution

It introduces a new method for optimizing proximity thermometers using experimental device variations and a theoretical model based on Usadel equations and Coulomb blockade.

Findings

Optimal device configurations improve sensitivity.

The theoretical model accurately predicts device performance.

Calibration techniques are established for future improvements.

Abstract

We present a set of experiments to optimize the performance of the noninvasive thermometer based on proximity superconductivity. Current through a standard tunnel junction between an aluminum superconductor and a copper electrode is controlled by the strength of the proximity induced to this normal metal, which in turn is determined by the position of a direct superconducting contact from the tunnel junction. Several devices with different distances were tested. We develop a theoretical model based on Usadel equations and dynamic Coulomb blockade which reproduces the measured results and yields a tool to calibrate the thermometer and to optimize it further in future experiments.