[18p-S2_202-1~10] KS.2 Quantum Information Engineering Group

3:30 PM - 3:45 PM JST(6:30 AM - 6:45 AM UTC)

[18p-S2_202-6] Enhanced Coherence in Transmon Qubits Based on Sidewall Spacer Passivated Epitaxial NbN/AlN/NbN Junctions

〇(M2)Koki Honda¹, Daiki Kurihara¹, Tokunoshin Uchida¹, Hiroki Kutsuma¹, Hirotaka Terai², Taro Yamashita¹ (1.Tohoku Univ., 2.NICT)

Keywords:

superconducting qubit,sidewall spacer structure,NbN/AlN/NbN Josephson junction

In epitaxial NbN/AlN/NbN junctions, decoherence induced by two-level systems (TLSs) is expected to be suppressed by employing a crystalline aluminum nitride (AlN) tunnel barrier. In this work, we focused on the sidewall spacer structure, which has been applied to Nb-based qubits and demonstrated improved coherence properties. We fabricated superconducting transmon qubits with sidewall spacer passivated NbN/AlN/NbN junctions on high-resistivity Si wafers. We will discuss the details of the fabrication process and the measurement results of transmon qubits with these junctions.