Ultrahigh Linearity of the Magnetic-Flux-to-Voltage Response of Proximity-Based Mesoscopic Bi-SQUIDs

Superconducting double-loop interferometers (bi-SQUIDs) have been introduced to produce magnetic flux sensors specifically designed exhibit ultra-highly linear voltage response as a function of the flux. These devices are very important for quantum sensing and signal processing signals oscillating at radio-frequencies range electromagnetic spectrum. Here, we report an Al bi-SQUIDs based on proximitized mesoscopic Cu Josephson junctions. Such scheme provides alternative fabrication approach conventional tunnel junction-based interferometers, where junction characteristics and, consequently, flux-to-voltage flux-to-critical current device can be largely easily tailored by geometry metallic weak-links. We discuss performance such showing full characterization switching drop \textit{vs.} temperatures operation ranging from 30 mK $\sim 1$ K. The figure merit transfer total harmonic distortion also discussed. latter estimate linearity response, which obtained values large 45 dB. result let us foresee already pair with that achieved in arrays composed hundreds interferometers.