Contribution of dielectrics to frequency and noise of NbTiN superconducting resonators

Abstract

We study NbTiN resonators by measurements of the temperature dependent resonance frequency and frequency noise. Additionally, resonators are studied covered with $\mathrm{Si}{\mathrm{O}}_x$ dielectric layers of various thicknesses. The resonance frequency develops a nonmonotonic temperature dependence with increasing $\mathrm{Si}{\mathrm{O}}_x$ layer thickness. The increase in the noise is independent of the $\mathrm{Si}{\mathrm{O}}_x$ thickness, demonstrating that the noise is not dominantly related to the low temperature resonance frequency deviations.