Kavli Affiliate: Kristin A. Persson
| First 5 Authors: Evan Sheridan, Thomas F. Harrelson, Eric Sivonxay, Kristin A. Persson, M. Virginia P. Altoé
| Summary:
The performance of superconducting qubits is orders of magnitude below what
is expected from theoretical estimates based on the loss tangents of the
constituent bulk materials. This has been attributed to the presence of
uncontrolled surface oxides formed during fabrication which can introduce
defects and impurities that create decoherence channels. Here, we develop an ab
initio Shiba theory to investigate the microscopic origin of magnetic-induced
decoherence in niobium thin film superconductors and the formation of native
oxides. Our ab initio calculations encompass the roles of structural disorder,
stoichiometry, and strain on the formation of decoherence-inducing local spin
moments. With parameters derived from these first-principles calculations we
develop an effective quasi-classical model of magnetic-induced losses in the
superconductor. We identify d-channel losses (associated with oxygen vacancies)
as especially parasitic, resulting in a residual zero temperature surface
impedance. This work provides a route to connecting atomic scale properties of
superconducting materials and macroscopic decoherence channels affecting
quantum systems.
| Search Query: ArXiv Query: search_query=au:”Kristin A. Persson”&id_list=&start=0&max_results=10