Suppression of the critical current of a balanced SQUID

TL;DR

This paper experimentally investigates a balanced SQUID with three Josephson junctions, showing that its critical current suppression depends mainly on inductances, achieving a suppression ratio over 300.

Contribution

It demonstrates a balanced SQUID design where critical current suppression is primarily limited by inductances, not junction parameters.

Findings

Critical current suppression ratio exceeds 300.

Suppression depends mainly on SQUID inductances.

Maximum critical current observed is 30 nA.

Abstract

We present an experimental study of the magnetic flux dependence of the critical current of a balanced SQUID with three Josephson junctions in parallel. Unlike for ordinary dc SQUIDs, the suppression of the critical current does not depend on the exact parameters of the Josephson junctions. The suppression is essentially limited only by the inductances of the SQUID loops. We demonstrate a critical current suppression ratio of higher than 300 in a balanced SQUID with a maximum critical current 30 nA.