Evaluation of Self-Field Effects in Magnetometers Based on Meander-Shaped Arrays of Josephson Junctions or SQUIDs Connected in Series.

Arrays of superconducting quantum interference devices (SQUIDs) are highly sensitive magnetometers that can operate without a flux-locked loop, as opposed to single SQUID magnetometers. They have no source of ambiguity and benefit from a larger bandwidth. They can be used to measure absolute magnetic fields with a dynamic range scaling as the number of SQUIDs they contain.

Dynamic properties of high-T superconducting nano-junctions made with a focused helium ion beam.

The Josephson junction (JJ) is the corner stone of superconducting electronics and quantum information processing. While the technology for fabricating low T JJ is mature and delivers quantum circuits able to reach the "quantum supremacy", the fabrication of reproducible and low-noise high-T JJ is still a challenge to be taken up. Here we report on noise properties at RF frequencies of recently introduced high-T Josephson nano-junctions fabricated by mean of a Helium ion beam focused at sub-nanometer scale on a YBaCuO thin film.