2015/10/31 by Jan Goetz, Frank Deppe, Max Haeberlein +10
Physics and Astronomy · #Coplanar waveguide #Electrical conductor #Josephson effect #Microwave #Niobium #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Resonator #Substrate (aquarium) #Superconducting and THz Device Technology #Superconductivity #cond-mat.mes-hall #cond-mat.supr-con
paper · pdf · doi:10.1063/1.4939299
published as J. Appl. Phys. 119, 015304 (2016)
openalex publication_date 2016/01/05 · arxiv created 2016/01/23 · arxiv updated 2016/01/26 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present a systematic analysis of the internal losses of superconducting coplanar waveguide microwave resonators based on niobium thin films on silicon substrates. In particular, we investigate losses introduced by Nb/Al interfaces in the center conductor, which is important for experiments where Al based Josephson junctions are integrated into Nb based circuits. We find that these interfaces can be a strong source for two-level state (TLS) losses, when the interfaces are not positioned at current nodes of the resonator. In addition to TLS losses, for resonators including Al, quasiparticle losses become relevant above 200 mK. Finally, we investigate how losses generated by eddy currents in conductive material on the backside of the substrate can be minimized by using thick enough substrates or metals with high conductivity on the substrate backside.