Materials loss characterization using superconducting microwave resonators

ORAL

Abstract

Continued improvements in the relaxation and coherence times of niobium and tantalum superconducting qubits have been recently demonstrated. Nonetheless, the device performance is still limited by materials loss, such as two-level system defects at poorly controlled interfaces. In this work, we characterized Ta/Nb lumped element resonators with varying material composition to compare different loss mechanisms between tantalum and niobium circuits. We also employed resonator design with diverse impedance to identify the dominant regime of defect coupling. Critical parameters such as surface participation ratio at interfaces are extracted through two-step finite-element simulation and correlate with the results from extensive materials characterization.

*This work was funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under Contract No. DE-AC02-05-CH11231 "High Coherence Multilayer Superconducting Structures for Large Scale Qubit Integration and Photonic Transduction program (QIS-LBNL) and the Samsung Advanced Institute of Technology under Research Agreement 37305. Work at the Molecular Foundry was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02- 05CH11231 (SEM, TEM, and XPS characterization and data analysis).

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Presenters

  • Ziqi (Candice) Kang

    • University of California, Berkeley

Authors

  • Ziqi (Candice) Kang

    • University of California, Berkeley

  • Kan-Heng Lee

    • Lawrence Berkeley National Laboratory

  • Larry Chen

    • University of California, Berkeley

  • Maria Virginia Pires Altoe

    • Lawrence Berkeley National Laboratory

  • David I Santiago

    • Lawrence Berkeley National Laboratory

  • Irfan Siddiqi

    • University of California, Berkeley