# Crossed Andreev Reflection in InSb Flake Josephson Junctions

## TL;DR

This paper investigates superconducting interference in InSb flake Josephson junctions, revealing an even-odd pattern linked to crossed Andreev reflection, with implications for topological states and non-local entanglement.

## Contribution

It demonstrates the occurrence of crossed Andreev reflection in InSb flakes and links it to specific edge conduction and unique interference patterns, advancing understanding of non-local superconducting processes.

## Key findings

- Observation of an even-odd interference pattern.
- Identification of edge-specific conduction related to crystal facets.
- Evidence supporting crossed Andreev reflection as the underlying mechanism.

## Abstract

We study superconducting quantum interference in InSb flake Josephson junctions. An even-odd effect in the amplitude and periodicity of the superconducting quantum interference pattern is found. Interestingly, the occurrence of this pattern coincides with enhanced conduction at both edges of the flake, as is deduced from measuring a SQUID pattern at reduced gate voltages. We identify the specific crystal facet of the edge with enhanced conduction, and confirm this by measuring multiple devices. Furthermore, we argue the even-odd effect is due to crossed Andreev reflection, a process where a Cooper pair splits up over the two edges and recombines at the opposite contact. An entirely $h/e$ periodic SQUID pattern, as well as the observation of both even-odd and odd-even effects, corroborates this conclusion. Crossed Andreev reflection could be harnessed for creating a topological state of matter or performing experiments on the non-local spin-entanglement of spatially separated Cooper pairs.