[C-6] Quantum Computing IV

[C-6-04] Reducing Microwave Dielectric Losses of Niobium Superconducting Resonators by a Tantalum Cap Layer

〇Yoshiro Urade¹, Kunihiro Inomata¹, Kay Yakushiji¹, Manabu Tsujimoto¹, Takahiro Yamada¹, Wataru Mizubayashi¹ (1. AIST (Japan))

Presentation style: On-site (in-person)

https://doi.org/10.7567/SSDM.2022.C-6-04

Niobium (Nb), a common material for electrodes of state-of-the-art superconducting qubits, experiences large microwave dielectric losses due to its surface oxide. Mitigating such losses of superconducting materials is crucial for improving the quality of superconducting qubits. To this end, we propose adding a tantalum cap layer on a Nb film. Superconducting resonators based on the composite film have been characterized using microwaves, and a significant increase in the internal quality factor of the resonators has been confirmed. The proposed composite film is expected to improve the coherence time of superconducting qubits.