Experimental evidence for a surface distribution of two-level systems in superconducting lithographed microwave resonators

Abstract

We present measurements of the temperature-dependent frequency shift of five niobium superconducting coplanar waveguide microresonators with center strip widths ranging from 3 $\mu$m to 50 $\mu$m, taken at temperatures in the range 100-800 mK, far below the 9.2 K transition temperature of niobium. These data agree well with the two-level system (TLS) theory. Fits to this theory provide information on the number of TLS that interact with each resonator geometry. The geometrical scaling indicates a surface distribution of TLS, and the data are consistent with a TLS surface layer thickness of order a few nm, as might be expected for a native oxide layer.

3 figures, submitted to APL

References in corpus (3)

• Coherent quantum state storage and transfer between two phase qubits via a resonant cavity
• Microwave Dielectric Loss at Single Photon Energies and milliKelvin Temperatures
• Temperature Dependence of the Frequency and Noise of Superconducting Coplanar Waveguide Resonators

Cited by in corpus (5)

• Controlling the spontaneous emission of a superconducting transmon qubit
• Two-resonator circuit QED: A superconducting quantum switch
• Microwave response of vortices in superconducting thin films of Re and Al
• A semi-empirical model for two-level system noise in superconducting microresonators
• Contribution of dielectrics to frequency and noise of NbTiN superconducting resonators