{\pi} junction transition in InAs self-assembled quantum dot coupled with SQUID

TL;DR

This study demonstrates a { extpi} junction transition in InAs self-assembled quantum dots coupled with a SQUID, revealing controllable phase shifts and supercurrent behavior relevant for quantum information technologies.

Contribution

It provides the first direct observation of { extpi} phase shift and negative supercurrent in InAs SAQDs coupled to a SQUID, with tunable energy levels and coupling.

Findings

Observation of { extpi} phase shift in InAs SAQDs

Control of supercurrent via gate tuning

Potential for quantum information device applications

Abstract

We report the transport measurements on the InAs self-assembled quantum dots (SAQDs) which have a unique structural zero-dimensionality, coupled to a superconducting quantum interference device (SQUID). Owing to the SQUID geometry, we directly observe a {\pi} phase shift in the current phase relation and the negative supercurrent indicating {\pi} junction behavior by not only tuning the energy level of SAQD by back-gate but also controlling the coupling between SAQD and electrodes by side-gate. Our results inspire new future quantum information devices which can link optical, spin, and superconducting state.