Comparison of Nb and Ta pentoxide loss tangents for superconducting quantum devices
Abstract
Superconducting transmon qubits are commonly made with thin-film Nb wiring, but recent studies have shown increased performance with Ta wiring. In this work, we compare the resonator-induced single photon, millikelvin dielectric loss for pentoxides of Nb (Nb2O5) and Ta (Ta2O5) in order to further understand limiting losses in qubits. Nb and Ta pentoxides of three thicknesses are deposited via pulsed laser deposition onto nominally identical coplanar waveguide resonators. The two-level system loss tangent is determined to be 0.0064 (0.0035) for Nb2O5 (Ta2O5) for a dielectric constant of 10. This work indicates that qubits with Nb wiring are affected by higher loss arising from the native pentoxide itself, likely in addition to the presence of suboxides, which are largely absent in Ta.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (17)
D. P. Goronzy
Department of Materials Science and Engineering, Northwestern University 1 , Evanston, Illinois 60208,
W. W. Mah
Department of Materials Science and Engineering, Northwestern University 1 , Evanston, Illinois 60208,
P. G. Lim
Applied Physics Graduate Program, Northwestern University 2 , Evanston, Illinois 60208,
T. Guess
National Institute for Standards and Technology Boulder 3 , Boulder, Colorado 80309,
S. Majumder
D. A. Garcia-Wetten
Department of Materials Science and Engineering, Northwestern University 1 , Evanston, Illinois 60208,
M. J. Walker
Department of Materials Science and Engineering, Northwestern University 1 , Evanston, Illinois 60208,
J. Ramírez
Departamento de Ingeniería Química Industrial y del Medio Ambiente, Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid 2 , 28006 Madrid,
W.-R. Syong
National Institute for Standards and Technology Boulder 3 , Boulder, Colorado 80309,
D. Bennett
National Institute for Standards and Technology Boulder 3 , Boulder, Colorado 80309,
M. Vissers
National Institute of Standards and Technology 2 , Boulder, Colorado 80305,
R. dos Reis
Department of Materials Science and Engineering, Northwestern University 1 , Evanston, Illinois 60208,
T. Pham
V. P. Dravid
Department of Materials Science and Engineering, Northwestern University 1 , Evanston, Illinois 60208,
M. C. Hersam
Department of Materials Science and Engineering, Northwestern University 1 , Evanston, Illinois 60208,
M. J. Bedzyk
Department of Materials Science and Engineering, Northwestern University 1 , Evanston, Illinois 60208,
C. R. H. McRae
National Institute for Standards and Technology Boulder 3 , Boulder, Colorado 80309,