A ballistic two-dimensional-electron-gas Andreev interferometer

TL;DR

This paper demonstrates a ballistic Andreev interferometer using an InAs 2D electron gas with superconducting Nb, showing strong magnetic modulation, low flux noise, and operation up to 7K, paving the way for advanced quantum devices.

Contribution

The work introduces a novel ballistic Andreev interferometer based on InAs 2D electron gas coupled with Nb, enabling new quantum applications and investigations.

Findings

Strong magnetic modulations observed due to quasiparticle interference.

Flux noise measured at approximately 80 μΦ₀/√Hz.

Voltage oscillations persist up to about 7 K.

Abstract

We report the realization and investigation of a ballistic Andreev interferometer based on an InAs two dimensional electron gas coupled to a superconducting Nb loop. We observe strong magnetic modulations in the voltage drop across the device due to quasiparticle interference within the weak-link. The interferometer exhibits flux noise down to $\sim 80\, \mu\Phi_0/\sqrt{\textrm{Hz}}$, and a robust behavior in temperature with voltage oscillations surviving up to $\sim7\,$K. Besides this remarkable performance, the device represents a crucial first step for the realization of a fully-tunable ballistic superconducting magnetometer and embodies a potential new platform for the investigation of Majorana bound states as well as non-local entanglement of Cooper pairs.