Granular superconductors for high kinetic inductance and low loss quantum devices

Granular aluminum is a promising material for high kinetic inductance devices such as qubit circuits. It has the advantage over atomically disordered materials such as NbN_x, to maintain a high kinetic inductance concomitantly with a high quality factor. We show that high quality nano-scale granular aluminum films having a sharp superconducting transition with normal state resistivity values on the order of $1×105 μΩ cm$ and kinetic inductance values on the order of $10 nH/◻$ can be obtained, surpassing the state-of-the-art values. We argue that this is a result of the different nature of the metal-to-insulator transition, being electronic correlations driven (Mott type) in the former and disorder driven (Anderson type) in the latter.