Non local Andreev reflection in a carbon nanotube superconducting quantum interference device

TL;DR

This paper explores a carbon nanotube SQUID that exhibits non-local Andreev reflection, affecting its critical current and phase relation, and offers insights into phase coherence in crossed Andreev processes.

Contribution

It introduces a detailed analysis of non-local Andreev reflection in a carbon nanotube SQUID, including effects of interface transparency and implications for phase coherence.

Findings

Non local processes reduce the critical current.

Current-phase relation is modified by non local effects.

Device geometry can probe phase coherence of crossed Andreev reflection.

Abstract

We investigate a superconducting quantum interference device (SQUID) based on carbon nanotubes in a fork geometry [J.-P. Cleuziou {\it et al.}, Nature Nanotechnology {\bf 1}, 53 (2006)], involving tunneling of evanescent quasiparticles through a superconductor over a distance comparable to the superconducting coherence length, with therefore ``non local'' processes generalizing non local Andreev reflection and elastic cotunneling. Non local processes induce a reduction of the critical current and modify the current-phase relation. We discuss arbitrary interface transparencies. Such devices in fork geometries are candidates for probing the phase coherence of crossed Andreev reflection.