Elucidating the local atomic and electronic structure of amorphous oxidized superconducting niobium films
Abstract
Qubits made from superconducting materials are a mature platform for quantum information science application, such as quantum computing. However, material-based losses are now a limiting factor in reaching the coherence times needed for applications. In particular, knowledge of the atomistic structure and properties of the circuit materials is needed to identify, understand, and mitigate material-based decoherence channels. In this work, we characterize the atomic structure of the native oxide film formed on Nb resonators by comparing fluctuation electron microscopy experiments to density functional theory calculations, finding that an amorphous layer is consistent with an Nb2O5 stoichiometry. Comparing x-ray absorption measurements at the Oxygen K edge with first-principles calculations, we find evidence of d-type magnetic impurities in our sample, known to cause impedance in proximal superconductors. This work identifies the structural and chemical composition of the oxide layer grown on Nb superconductors and shows that soft x-ray absorption can fingerprint magnetic impurities in these superconducting systems.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 13, 2021
- Source ID
- 10.1063/5.0069549
Entities
People
- Adam M Schwartzberg
- Alpha T. N'Diaye
- D Frank Ogletree
- Ellis Kennedy
- Evan Sheridan
- Irfan Siddiqi
- John Vinson
- M. Virginia P. Altoe
- Mary C. Scott
- Sinéad Griffin
- Thomas Harrelson
Organizations
- Advanced Light Source
- Air Force Office of Scientific Research
- Fulbright Association
- King's College London
- Lawrence Berkeley National Laboratory
- National Institute of Standards and Technology
- National Science Foundation
- United States Department of Energy
- University of California