Loss mechanisms in superconducting thin film microwave resonators

Autor: M. Haeberlein, Christoph W. Zollitsch, Edwin P. Menzel, F. Wulschner, P. Eder, Jan Goetz, Frank Deppe, A. Marx, Michael Fischer, Rudolf Gross, Kirill G. Fedorov, Sebastian Meier, E. Xie
Rok vydání: 2016
Předmět:
Zdroj: Journal of Applied Physics. 119:015304
ISSN: 1089-7550
0021-8979
DOI: 10.1063/1.4939299
Popis: 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.
Databáze: OpenAIRE