Josephson diode effect in monolithic dc-SQUIDs based on 3D Dayem nanobridges

TL;DR

This paper presents a theory, fabrication, and demonstration of a monolithic dc-SQUID with 3D Dayem nanobridges that acts as a magnetic flux-tunable supercurrent diode with up to 20% rectification efficiency, without needing a finite loop inductance.

Contribution

It introduces a novel superconducting diode device based on 3D Dayem nanobridges that achieves efficient rectification without the limitations of loop inductance.

Findings

Achieves up to 20% rectification efficiency

Operates as a magnetic flux-tunable supercurrent diode

Does not require finite loop inductance for rectification

Abstract

It was recently experimentally proved that the superconducting counterpart of a diode, i.e., a device that realizes nonreciprocal Cooper pairs transport, can be realized by breaking the spatial and time-reversal symmetry of a system simultaneously. Here we report the theory, fabrication, and operation of a monolithic dc superconducting quantum interference device (dc-SQUID) that embedding three-dimensional (3D) Dayem nanobridges as weak links realizes an efficient and magnetic flux-tunable supercurrent diode. The device is entirely realized in Al and achieves a maximum rectification efficiency of $\sim 20\%$, which stems from the high harmonic content of its current-to-phase relation only without the need of any sizable screening current caused by a finite loop inductance. Our interferometer can be easily integrated with state-of-the-art superconducting electronics, and since it does not require a finite loop inductance to provide large rectification its downsizing is not limited by the geometrical constraints of the superconducting ring.