Microresonators Fabricated from High-Kinetic-Inductance Aluminum Films

We have studied superconducting coplanar-waveguide (CPW) resonators fabricated from disordered films of aluminum. The very high kinetic inductance of these films, inherent to disordered materials, allows us to implement ultrashort (200 mu m at 5 GHz resonance frequency) and high-impedance (up to 5 k Omega) half-wavelength resonators. We have shown that the intrinsic losses in these resonators at temperatures less than or similar to 250 mK are limited by resonator coupling to two-level systems (TLSs) in the environment. The demonstrated internal quality factors are comparable with those for CPW resonators made of conventional superconductors. The high kinetic inductance and well-understood losses make these disordered aluminum resonators promising for a wide range of microwave applications, which include kinetic-inductance photon detectors and superconducting quantum circuits.