Low-loss superconducting resonant circuits using vacuum-gap-based microwave components

TL;DR

This paper demonstrates the fabrication of high-quality superconducting microwave circuits using vacuum-gap technology that reduces dielectric losses, achieving high internal quality factors and enabling complex quantum devices.

Contribution

The authors developed an improved vacuum-gap fabrication process with novel wiring crossovers and capacitors, enhancing yield and performance of superconducting circuits.

Findings

Achieved internal quality factors up to 165,000 at 50 mK.

Demonstrated large vacuum-gap capacitors up to 180 pF.

Produced complex circuits like multiplexed resonators and phase qubits.

Abstract

We have produced high-quality complex microwave circuits, such as multiplexed resonators and superconducting phase qubits, using a "vacuum-gap" technology that eliminates lossy dielectric materials. We have improved our design and fabrication strategy beyond our earlier work, leading to increased yield, enabling the realization of these complex circuits. We incorporate both novel vacuum-gap wiring crossovers (VGX) for gradiometric inductors and vacuum-gap capacitors(VGC) on chip to produce resonant circuits that have large internal quality factors (30,000<Q<165,000) at 50 mK, outperforming most dielectric-filled devices. Resonators with VGCs as large as 180 pF confirm single mode behavior of our lumped-element components.