Fabrication and surface treatment of electron-beam evaporated niobium for low-loss coplanar waveguide resonators

ORAL

Abstract

We characterize low-loss electron-beam evaporated niobium thin films deposited under ultra-high vacuum conditions. Slow deposition yields films with a high superconducting transition temperature (9.20±0.06 K) as well as a residual resistivity ratio of 4.8. We fabricate the films into coplanar waveguide resonators to extract the intrinsic loss due to the presence of two-level-system fluctuators using microwave measurements. For a coplanar waveguide resonator gap of 2 μm, the films exhibit filling-factor-adjusted two-level-system loss tangents as low as 1.5×10−7 with single-photon regime internal quality factors in excess of one million after removing native surface oxides of the niobium.

*This research was supported by NSF Grant No. PHY-1752844 (CAREER), NSF Grant No. DMR-1945278 (CAREER), and the John Templeton Foundation Grant No. 61835.

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Publication: https://aip.scitation.org/doi/full/10.1063/5.0066441

Presenters

  • Daria Kowsari

    • Washington University, St. Louis

Authors

  • Daria Kowsari

    • Washington University, St. Louis

  • Kaiwen Zheng

    • Washington University
    • Washington University, St. Louis

  • Jonathan T Monroe

    • Washington University, St. Louis

  • Nathan J Thobaben

    • Saint Louis University

  • Xinyi Du

    • Washington University, St. Louis

  • Patrick M Harrington

    • Massachusetts Institute of Technology MI
    • Department of Electrical Engineering & Computer Science and Department of Physics, Massachusetts Institute of Technology
    • Massachusetts Institute of Technology MIT
    • Massachusetts Institute of Technology

  • Erik A Henriksen

    • Washington University, St. Louis

  • David S Wisbey

    • Saint Louis University

  • Kater W Murch

    • Washington University, St. Louis