Dielectric loss extraction for superconducting microwave resonators
Corey Rae H. McRae, Russell Lake, Junling Long, Mustafa Bal, Xian Wu, Battogtokh Jugdersuren, Thomas Metcalf, Xiao Liu, David P. Pappas
The investigation of two-level-state (TLS) loss in dielectric materials and interfaces remains at the forefront of materials research in superconducting quantum circuits. We demonstrate a method of TLS loss extraction of a thin film dielectric by measuring a lumped element resonator fabricated from a superconductor-dielectric-superconductor trilayer. We extract the dielectric loss by formulating a circuit model for a lumped element resonator with TLS loss and then fitting to this model using measurements from a set of three resonator designs: a coplanar waveguide resonator, a lumped element resonator with an interdigitated capacitor, and a lumped element resonator with a parallel plate capacitor that includes the dielectric thin film of interest. Unlike other methods, this allows accurate measurement of materials with TLS loss lower than 10−6. We demonstrate this method by extracting a TLS loss of 1.02x10−3 for sputtered Al2O3 using a set of samples fabricated from an Al/ Al2O3 /Al trilayer. We observe a difference of 11% between extracted loss of the trilayer with and without the implementation of this method.