Electrical control of Kondo effect and superconducting transport in a side-gated InAs quantum dot Josephson junction

TL;DR

This study demonstrates electrical control over the Kondo effect and superconducting transport in an InAs quantum dot Josephson junction, revealing how gate tuning influences the interplay between Kondo correlations and superconductivity.

Contribution

It introduces a side-gate technique to tune QD-lead coupling while maintaining constant electron number, enabling detailed study of Kondo-superconductor interactions.

Findings

Supercurrent decreases as Kondo temperature drops below the superconducting gap.

Side-gate tuning effectively modulates the QD-lead tunnel coupling.

Qualitative agreement with theoretical predictions on Kondo-superconductivity competition.

Abstract

We measure the non-dissipative supercurrent in a single InAs self-assembled quantum dot (QD) coupled to superconducting leads. The QD occupation is both tuned by a back-gate electrode and lateral side-gate. The geometry of the side-gate allows tuning of the QD-lead tunnel coupling in a region of constant electron number with appropriate orbital state. Using the side-gate effect we study the competition between Kondo correlations and superconducting pairing on the QD, observing a decrease in the supercurrent when the Kondo temperature is reduced below the superconducting energy gap in qualitative agreement with theoretical predictions.