Noise and dissipation in superconducting granular aluminum circuits

In recent years, granular aluminum has emerged to a promising candidate to fill the gap of a high performance, high kinetic inductance material in superconducting detectors, amplifiers, and qubits. In this work, the noise properties of superconducting resonators made from granular aluminum films are studied in detail. The fluctuations of their fundamental frequency are analyzed, and electric fields are employed to investigate dielectric loss, revealing strongly coupled, microscopic two-level defects. The findings lead to a better understanding of disordered materials in the context of superconducting qubits and other quantum circuits.