Phase dynamics in an AC driven multiterminal Josephson junction analogue

TL;DR

This paper presents an analog circuit model to study the complex phase dynamics and inverse AC Josephson effect in multiterminal Josephson junctions, revealing stable phase-locked states and the influence of circuit parameters.

Contribution

It introduces a tunable analog circuit that emulates three-terminal Josephson junction dynamics, enabling exploration of phase locking and Shapiro steps beyond low-temperature experiments.

Findings

Integer phase locked states observed in overdamped networks

Fractional Shapiro steps appear with higher quality factors

Transverse coupling influences junction synchronization

Abstract

In the presence of an AC drive, multiterminal Josephson junctions exhibit the inverse AC Josephson effect, where the oscillations of the superconducting phase of each junction can lock onto one another or onto the external drive. The competition between these different phase locked states results in a complex array of quantized voltage plateaus whose stability strongly depend on the circuit parameters of the shunted junctions. This phase diagram cannot be explored with low temperature transport experiments alone, given the breadth of the parameter space, so we present an easily tunable analog circuit whose dynamical properties emulate those of a three terminal junction. We focus on the observation of the multiterminal inverse AC Josephson effect, and we discuss how to identify Shapiro steps associated with each of the three junctions as well as their quartet states. We only observe integer phase locked states in strongly overdamped networks, but fractional Shapiro steps appear as well when the quality factor of the junctions increases. Finally, we discuss the role of transverse coupling in the synchronization of the junctions.