[10p-A24-1~15] 11.4 Junction and circuit fabrication process, digital applications

2:00 PM - 2:15 PM JST(5:00 AM - 5:15 AM UTC)

[10p-A24-1] All-Nitride Superconducting Qubits with Energy Relaxation Times Exceeding 800 μs

〇Sunmi Kim¹, Hirotaka Terai², Tomoko Fuse¹, Sahel Ashhab¹, Shotaro Shirai³, Atsushi Noguchi^3,4,5, Kouichi Semba^1,6 (1.NICT Tokyo, 2.NICT Kobe, 3.RIKEN RQC, 4.Univ. of Tokyo (Arts&Sci.), 5.InaRIS, 6.Univ. of Tokyo (Sci.))

Keywords:

superconducting qubit,NbN,Coherence

Compared to conventional Al-based devices, all-nitride superconducting qubits offer distinct advantages, such as the formation of epitaxial tunnel barriers that reduce two-level system (TLS) noise, and a larger energy gap that effectively suppresses quasiparticle-induced decoherence. In this talk, we report our recent progress in improving the coherence times of all-nitride transmon qubits fabricated on silicon substrates. Through the optimization of thin-film growth and device geometry, combined with the integration of TiN resonators to minimize dielectric losses and an upgraded sample packaging design, we have successfully achieved an energy relaxation time (T₁) exceeding 800 μs. This achievement represents a significant milestone toward realizing large-scale quantum processors.