Crossed Andreev reflection and elastic co-tunneling in a three-site Kitaev chain nanowire device

TL;DR

This paper demonstrates the realization of a three-site Kitaev chain in an InSb nanowire device, showing pairwise crossed Andreev reflection and elastic co-tunneling, advancing the development of topological superconductivity in quantum-dot systems.

Contribution

It provides the first experimental demonstration of a minimal three-site Kitaev chain with well-defined bulk and edge, highlighting key processes for topological superconductivity.

Findings

Observation of pairwise crossed Andreev reflection

Detection of elastic co-tunneling between neighboring dots

Sequential tunneling involving all three quantum dots

Abstract

The formation of a topological superconducting phase in a quantum-dot-based Kitaev chain requires nearest neighbor crossed Andreev reflection and elastic co-tunneling. Here we report on a hybrid InSb nanowire in a three-site Kitaev chain geometry - the smallest system with well-defined bulk and edge - where two superconductor-semiconductor hybrids separate three quantum dots. We demonstrate pairwise crossed Andreev reflection and elastic co-tunneling between both pairs of neighboring dots and show sequential tunneling processes involving all three quantum dots. These results are the next step towards the realization of topological superconductivity in long Kitaev chain devices with many coupled quantum dots.