[17p-W8E_308-1~15] 11.5 Junction and circuit fabrication process, digital applications

4:30 PM - 4:45 PM JST(7:30 AM - 7:45 AM UTC)

[17p-W8E_308-11] Coherence measurement of nitride superconducting transmon qubit

〇Tomoko Fuse¹, Sunmi Kim¹, Sahel Ashhab¹, Shotaro Shirai², Atsushi Noguchi^2,3,4, Fumiki Yoshihara^1,5, Hirotaka Terai¹ (1.NICT, 2.RIKEN, 3.Univ. of Tokyo, 4.InaRIS, 5.Tokyo Univ. of Sci.)

Keywords:

superconducting qubit,epitaxial Josephson junction,transmon

We fabricated a nitride transmon qubit, where participation of the junction capacitance is 10 % of the total capacitance, using a NbN/AlN/NbN epitaxial Josephson junction on a Si substrate. We evaluated its coherence properties and observed an energy relaxation time, T₁, of 258 μs and a spin-echo dephasing time of 39 μs. The measurements were performed using a sample package, which has the same design as the package used to evaluate a transmon qubit with T₁ over 400 μs and a resonator with an internal quality factor over 10⁷ in a two-dimensional circuit.