Fabrication and characterization of low loss and high inductance Josephson tunnel junction chains for quantum circuits

Linear chains of tightly packed Josephson junctions can realize a very high kinetic inductance circuit element, superinductance, with minimal losses. Superinductance is used in a conventional fluxonium qubit, but it has also been put forward as a key element of a fault-tolerant quantum circuits toolbox [1]. We report fabrication and microwave characterization of linear Al/AlOx/Al Josephson tunnel junction chains and discuss their advantages and limitations as superinductors. [1]: 10.1103/PhysRevA.87.052306