Gate-control of the current-flux relation of a Josephson quantum interferometer based on proximitized metallic nanojuntions

TL;DR

This paper demonstrates a gate-controlled Josephson interferometer using proximitized metallic weak-links, showing tunable current-flux relations and potential for nanoscale magnetometry.

Contribution

It introduces a novel gate-tunable metallic Josephson interferometer with controllable current-flux behavior via electrostatic gating.

Findings

Gate voltage modifies the current-flux relation.

Presence of $\pi$-channels affects the phase coherence.

Interferometer shows potential for nanoscale magnetic sensing.

Abstract

We demonstrate an Al superconducting quantum interference device in which the Josephson junctions are implemented through gate-controlled proximitized Cu mesoscopic weak-links. The latter behave analogously to genuine superconducting metals in terms of the response to electrostatic gating, and provide a good performance in terms of current-modulation visibility. We show that, through the application of a static gate voltage, we are able to modify the interferometer current-flux relation in a fashion which seems compatible with the introduction of $\pi$-channels within the gated weak-link. Our results suggest that the microscopic mechanism at the origin of the suppression of the switching current in the interferometer is apparently phase coherent, resulting in an overall damping of the superconducting phase rigidity. We finally tackle the performance of the interferometer in terms of responsivity to magnetic flux variations in the dissipative regime, and discuss the practical relevance of gated proximity-based all-metallic SQUIDs for magnetometry at the nanoscale.