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arXiv · 2605.30425

Dually tunable YBCO coplanar waveguide resonators based on helium-ion-generated Josephson inductances

Kenny Fohmann·Timo J. Glebe-Märklin·Benedikt Wilde·Mohamad Kazouini·Christoph Schmid·Dieter Koelle·Reinhold Kleiner·Daniel Bothner
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Abstract

Superconducting microwave circuits with and without Josephson inductances are the Swiss Army knife for many experiments and technologies from quantum information science to astrophysical particle detectors. Despite a large variety of existing circuit types, thin film materials and Josephson junction technologies, a flexible and reliable platform for high-magnetic-field and high-temperature applications is yet to be found. In this manuscript, we investigate coplanar waveguide cavities made of the high-temperature cuprate superconductor YBa$_2$Cu$_3$O$_7$ (YBCO), integrated with Josephson inductances and quantum interferometers that are generated by the controlled local irradiation of the YBCO with a focused helium ion beam. We obtain strongly flux-tunable microwave resonators, which not only display periodic interferometer oscillations of resonance frequency and decay rate, but also a superimposed Fraunhofer-like modulation pattern. The latter originates from the magnetic field tuning of the individual Josephson junction critical currents due to the out-of-plane junction barriers. It allows adjusting resonance frequency and flux responsivity independently of each other, potentially enabling tunable microwave circuits with low sensitivity to external magnetic-field noise over a broad range of frequencies. Finally, we investigate the temperature dependence of the cavities, show that they have promising characteristics up to 14$\,$K, and present a model for the junction-induced cavity losses.

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Kenny Fohmann, Timo J. Glebe-Märklin, Benedikt Wilde, Mohamad Kazouini, Christoph Schmid, Dieter Koelle, Reinhold Kleiner, Daniel Bothner. 2026-05-28. Dually tunable YBCO coplanar waveguide resonators based on helium-ion-generated Josephson inductances. https://arxiv.org/abs/2605.30425

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