世界最高水準の長寿命超伝導共振器を開発～量子メモリや誤り訂正の基盤技術として期待～

2025-06-13 理化学研究所,情報通信研究機構,東京大学

スパイラル形状の高Q値超伝導共振器（イメージ）

＜関連情報＞

• https://www.riken.jp/press/2025/20250613_1/index.html
• https://epjquantumtechnology.springeropen.com/articles/10.1140/epjqt/s40507-025-00367-w

超伝導平面共振器における1000万に迫る本質的な品質係数：スパイラル形状が可能にする Intrinsic quality factors approaching 10 million in superconducting planar resonators enabled by spiral geometry

Yusuke Tominaga,Shotaro Shirai,Yuji Hishida,Hirotaka Terai & Atsushi Noguchi
EPJ Quantum Technology  Published:13 June 2025
DOI:https://doi.org/10.1140/epjqt/s40507-025-00367-w

Abstract

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 Q_i=(9.6±1.5)×10⁶ at the single-photon level and Q_i=(9.91±0.39)×10⁷ at high power, which is more than twice as high as those for coplanar waveguide (CPW) resonators under identical conditions on the same chip. 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).