Tunable Superconducting Coupling of Quantum Dots via Andreev Bound States in Semiconductor-Superconductor Nanowires

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 Letter, 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.

Automated summary

Semiconductor quantum dots have emerged as a promising platform for solid-state quantum simulation. However, the implementation of superconducting coupling between quantum dots mediated by Cooper pairs has been limited by tunability and suppression issues. In this study, the authors propose a method to achieve tunable effective couplings between quantum dots using Andreev bound states in a semiconductor-superconductor nanowire. They demonstrate that the properties of the Andreev bound states can be easily controlled to individually manipulate the coupling mediated by Cooper pairs and single electrons, while mitigating the problem of coupling suppression. The authors also suggest an experimental approach to extract the coupling strengths from resonant current in a three-terminal junction. This proposal opens up new possibilities for future experiments in the field.