Phase-Locking in Strongly Coupled Squid Cells

TL;DR

This paper investigates phase-locking phenomena in strongly coupled SQUID cells with minimal inductance, revealing unique locking behavior and phase transitions near half a flux quantum.

Contribution

It provides the first analytical and numerical analysis of phase-locking in strongly coupled SQUID cells with very small inductance, contrasting with traditional high-inductance models.

Findings

Junction phases are locked with small phase difference across most external flux values.

Phase difference rapidly approaches π near half a flux quantum.

Strong coupling leads to distinct phase-locking behavior compared to high-inductance SQUIDs.

Abstract

Within the RSJ model we performed an analytical and numerical investigation of SQUID cells consisting of two Josephson junctions shunted by an extremely small inductance leading to strong coupling of the elements. Contrary to the well-known behavior of cells shunted by a high inductance voltage phases of the junctions are locked with very small phase difference for almost all values of external flux. Only for external flux in the vicinity of half a flux quantum phase difference rises rapidly to $\pi$.