Understanding loss mechanisms in tantalum-based superconducting circuits

ORAL

Abstract

Tantalum as a material platform for superconducting qubits has shown longer relaxation times on average than other commonly used materials, such as Al, TiN, and Nb. In this work, we explore the loss mechanisms in tantalum circuits including loss tangent and defect coupling. We grow niobium and alpha-tantalum on silicon substrate, and fabricate lumped-element resonators with varying characteristics and composition in our experiments. Materials properties at each interface are extracted through two-step finite-element simulation and correlate with the results from extensive materials characterization including XPS, TEM and EDS. The work here will provide a pathway to understand the origin of the loss channels in group V element superconductors, and ultimately enable us to improve the resonator quality factor and qubit relaxation time in superconducting quantum circuits.

* 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). 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 P Altoe

    Lawrence Berkeley National Laboratory, Molecular Foundry, Lawrence Berkeley National Laboratory

  • David I Santiago

    Lawrence Berkeley National Laboratory

  • Irfan Siddiqi

    University of California, Berkeley