Non-local Supercurrent of Quartets in a Three-Terminal Josephson Junction

TL;DR

This paper reports the discovery of a non-local supercurrent carried by entangled electron quartets in a three-terminal Josephson junction, supported by experimental measurements and theoretical analysis.

Contribution

It introduces a novel non-local supercurrent mechanism involving quartets and a new type of Andreev bound state in three-terminal superconducting devices.

Findings

Observation of non-local supercurrent in three-terminal junctions

Existence of a new Andreev bound state in nonlinear regimes

Experimental validation through conductance and fluctuation measurements

Abstract

We report an observation of a new, non dissipative and non local supercurrent, carried by quartets; each consisting of four entangled electrons. The supercurrent is a result of a novel Andreev bound state (ABS), formed among three superconducting terminals. While in a two-terminal Josephson junction the usual ABS, and thus the DC Josephson current, exist only in equilibrium, in the present realization the ABS exists also in the strongly nonlinear regime (biased terminals). The presence of supercurrent carried by quartets was established by performing non-local conductance and cross-correlation of current fluctuations measurements, in different devices made of aluminum-InAs nanowire junctions. An extensive and detailed theoretical study is intertwined with the experimental results.