Observation of supercurrent enhancement in SNS junctions by non-equilibrium injection into supercurrent carrying bound Andreev states

TL;DR

This study demonstrates that non-equilibrium injection into Andreev bound states in a mesoscopic SNS device can enhance supercurrent, even at temperatures where equilibrium supercurrent is absent.

Contribution

First experimental observation of supercurrent enhancement via non-equilibrium injection into Andreev states in a three-terminal SNS device.

Findings

Supercurrent is maximized when injection bias equals the superconducting gap divided by e.

Enhancement persists at temperatures where equilibrium supercurrent vanishes.

Injection at specific bias conditions leads to supercurrent increase.

Abstract

We report for the first time enhancement of the supercurrent by means of injection in a mesoscopic three terminal planar SNSNS device made of Al on GaAs. When a current is injected from one of the superconducting Al electrodes at an injection bias $V=\Delta(T)/e$, the DC Josephson current between the other two superconducting electrodes has a maximum, giving evidence for an enhancement due to a non-equilibrium injection into bound Andreev states of the underlying semiconductor. The effect persists to temperatures where the equilibrium supercurrent has vanished.