Enhancing Intrinsic Quality Factors Approaching 10 Million in Superconducting Planar Resonators via Spiral Geometry

  1. Yusuke Tominaga,
  2. Shotaro Shirai,
  3. Yuji Hishida,
  4. Hirotaka Terai,
  5. and Atsushi Noguchi
This study investigates the use of spiral geometry in superconducting resonators to achieve high intrinsic quality factors, crucial for applications in quantum computation and quantum sensing. We fabricated Archimedean Spiral Resonators (ASRs) using domain-matched epitaxially grown titanium nitride (TiN) on silicon wafers, achieving intrinsic quality factors of Qi=(9.6±1.5)×106 at the single-photon level and Qi=(9.91±0.39)×107 at high power, significantly outperforming traditional coplanar waveguide (CPW) resonators. We conducted a comprehensive numerical analysis using COMSOL to calculate surface participation ratios (PRs) at critical interfaces: metal-air, metal-substrate, and substrate-air. Our findings reveal that ASRs have lower PRs than CPWs, explaining their superior quality factors and reduced coupling to two-level systems (TLSs).
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