8th RQC Seminar
Dr. Sunmi Kim（情報通信研究機構（NICT））
Superconducting qubits with nitride Josephson junctions
In this talk, I introduce our recent works on the development of all-nitride superconducting qubit on silicon substrate . We have fabricated an all-nitride capacitively-shunted flux qubit coupled to a half-wavelength coplanar waveguide resonator by utilizing the growth technique of a full-epitaxial NbN/AlN/NbN tri-layer. Also, by employing a Si substrate instead of a conventional MgO substrate for epitaxial growth of NbN film, this nitride flux qubit has demonstrated a significant improvement in coherence times, such as T1 = 16.3 μs and T2 = 21.5 μs, which are more than an order of magnitude longer than those reported in the literature using MgO substrates . These results are an important step towards constructing a new platform for superconducting quantum hardware.
 S. Kim et al., Communications Materials 2, 98 (2021).
 Y. Nakamura et al., Appl. Phys. Lett. 99, 212502 (2011).
Flyer: 8th RQC Seminar Flyer