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.