Coherent current states in mesoscopic four-terminal Josephson junction

TL;DR

This paper develops a comprehensive theory for ballistic four-terminal Josephson junctions, revealing nonlocal supercurrent coupling and magnetic flux effects in mesoscopic systems, with implications for controlling quantum states.

Contribution

It introduces a new theoretical framework for four-terminal Josephson junctions, highlighting nonlocal supercurrent interactions and magnetic flux-induced effects in mesoscopic structures.

Findings

Nonlocal coupling leads to flux-induced currents in other rings.

Magnetic flux can regulate phase distributions and supercurrents.

Current vortex states and phase slip centers can form under certain conditions.

Abstract

A theory is offered for the ballistic 4-terminal Josephson junction. The studied system consists of a mesoscopic two-dimensional normal rectangular layer which is attached in each side to the bulk superconducting banks (terminals). The relation between the currents through the different terminals, which is valid for arbitrary temperatures and junction sizes, is obtained. The nonlocal coupling of the supercurrents leads to a new effect, specific for the mesoscopic weak link between two superconducting rings; an applied magnetic flux through one of the rings produces a magnetic flux in the other ring even in the absence of an external flux through the other one. The phase dependent distributions of the local density of Andreev states, of the supercurrents and of the induced order parameter are obtained. The "interference pattern" for the anomalous average inside the two dimensional region can be regulated by the applied magnetic fluxes or the transport currents. For some values of the phase differences between the terminals, the current vortex state and the two dimensional phase slip center are appeared.