Compact superconducting microwave resonators based on Al-AlOx-Al capacitor

Abstract

We address the scaling-up problem for superconducting quantum circuits by using lumpedelement resonators based on a new fabrication method of aluminum -aluminum oxide -aluminum (Al/AlOx/Al) parallel-plate capacitors. The size of the resonators is only 0.04 mm 2 , which is more than one order smaller than the typical size of coplanar resonators (1 mm 2 ). The fabrication method we developed easily fits into the standard superconducting qubits fabrication process. We have obtained capacitance per area 14 fF/µm 2 and the internal quality factor 1 × 10 3 − 8 × 10 3 at the single-photon level. Our results show that such devices based on Al/AlOx/Al capacitors could be further applied to the qubit readout scheme, including resonators, filters, amplifiers, as well as microwave metamaterials and novel types of qubits, such as 0 − π qubit.