A ballistic quantum ring Josephson interferometer

TL;DR

This paper reports the creation of a ballistic Josephson interferometer using a quantum ring in an InAs heterostructure, demonstrating h/e flux periodicity and opening avenues for Majorana fermion research.

Contribution

It presents the first realization of a ballistic quantum ring Josephson interferometer with flux oscillations confirming ballistic transport.

Findings

Observed h/e flux periodicity in Josephson current

Confirmed ballistic nature of the device

Paves way for Majorana fermion studies

Abstract

We report the realization of a ballistic Josephson interferometer. The interferometer is made by a quantum ring etched in a nanofabricated two-dimensional electron gas confined in an InAs-based heterostructure laterally contacted to superconducting niobium leads. The Josephson current flowing through the structure shows oscillations with h/e flux periodicity when threading the loop with a perpendicular magnetic field. This periodicity, in sharp contrast with the h/2e one observed in conventional dc superconducting quantum interference devices, confirms the ballistic nature of the device in agreement with theoretical predictions. This system paves the way for the implementation of interferometric Josephson pi-junctions, and for the investigation of Majorana fermions.