Tunable superconducting coupling of quantum dots via Andreev bound states in semiconductor-superconductor nanowires

TL;DR

This paper proposes a method to achieve tunable superconducting coupling between quantum dots using Andreev bound states in semiconductor-superconductor nanowires, overcoming previous limitations in control and suppression.

Contribution

It introduces a novel approach to control quantum dot couplings via Andreev bound states, enabling independent tuning of Cooper pair and single-electron couplings.

Findings

Tunable effective couplings can be mediated by Andreev bound states.

Coupling suppression issues are significantly reduced.

Experimental extraction of coupling strengths is feasible through resonant current measurements.

Abstract

Semiconductor quantum dots have proven to be a useful platform for quantum simulation in the solid state. However, implementing a superconducting coupling between quantum dots mediated by a Cooper pair has so far suffered from limited tunability and strong suppression. This has limited applications such as Cooper pair splitting and quantum dot simulation of topological Kitaev chains. In this work, we propose how to mediate tunable effective couplings via Andreev bound states in a semiconductor-superconductor nanowire connecting two quantum dots. We show that in this way it is possible to individually control both the coupling mediated by Cooper pairs and by single electrons by changing the properties of the Andreev bound states with easily accessible experimental parameters. In addition, the problem of coupling suppression is greatly mitigated. We also propose how to experimentally extract the coupling strengths from resonant current in a three-terminal junction. Our proposal will enable future experiments that have not been possible so far.