Random telegraph fluctuations in granular microwave resonators

Microwave circuit electrodynamics of disordered superconductors is a very active research topic spawning wide range experiments and applications. For compact superconducting elements, the transition to an insulating state poses limit maximum attainable kinetic inductance. It is, therefore, vital study fundamental noise properties thin films close this transition, particularly in situations where good coherence temporal stability required. In paper, we present measurements on granular aluminum microwave resonators with high normal resistances, influence superconductor insulator phase visible. We trace fluctuations resonance frequency observe, addition 1/f pattern, distinct excess noise, reminiscent random telegraph signal. The shows strong dependency resistivity as well sample temperature but not applied power.