Supercurrent Quantization in Narrow Channel SNS Junctions

TL;DR

This paper investigates supercurrent quantization in narrow SNS Josephson junctions, revealing how Andreev levels form and lead to non-universal supercurrent quantization depending on junction parameters.

Contribution

It provides a detailed analysis of the excitation spectrum and supercurrent quantization in narrow ballistic SNS junctions, highlighting the dependence on junction parameters.

Findings

Supercurrent quantization occurs due to Andreev levels in narrow SNS junctions.

The quantization behavior is non-universal and varies with junction parameters.

Increasing chemical potential converts electronic levels into supercurrent-carrying Andreev levels.

Abstract

We determine the quasi-particle excitation spectrum in the normal region of a narrow ballistic superconductor--normal-metal--superconductor (SNS) Josephson contact. Increasing the effective chemical potential in the contact converts the electronic levels into Andreev-levels carrying supercurrent. The opening of these superchannels leads to a supercurrent quantization which exhibits a non-universal behavior in general and we discuss its dependence on the junction parameters.