SQUID based resistance bridge for shot noise measurement on low impedance samples

TL;DR

This paper introduces a SQUID-based resistance bridge capable of measuring shot noise in low impedance samples with high precision, enabling reliable analysis of Andreev reflection effects at cryogenic temperatures.

Contribution

The paper presents a novel SQUID-based resistance bridge that achieves high sensitivity and low intrinsic noise for shot noise measurements in low impedance samples.

Findings

Successful measurement of shot noise in superconductor/normal/superconductor junctions

Detection of Andreev reflection enhanced shot noise

System outperforms classical measurement schemes at 4.2K

Abstract

We present a resistance bridge which uses a SQUID to measure the shot noise in low impedance samples. The experimental requirements are high DC bias currents (typically 10mA) together with high AC sensitivity (pA/VHz). This system is used to investigate the shot noise in Superconductor/Normal/Superconductor junctions where Andreev reflection enhanced shot noise is expected. Because our setup has an intrinsic noise much smaller than the thermal noise of the resistance bridge at 4.2K, reliable results can be obtained on impedances out of the range of classical measurement schemes.