Planar Superconducting Whispering Gallery Mode Resonators

TL;DR

This paper presents a novel planar superconducting whispering gallery mode resonator architecture that achieves high quality factors and serves as a platform for materials characterization in quantum signal processing.

Contribution

It introduces a new '2.5D' resonator design combining 3D and planar features, with high energy storage efficiency and exceptional quality factors.

Findings

Internal Q factors above 3 million at single photon level

Stored 98% of energy in vacuum

Placed an upper bound on aluminum surface resistance (<250nOhms)

Abstract

We introduce a microwave circuit architecture for quantum signal processing combining design principles borrowed from high-Q 3D resonators in the quantum regime and from planar structures fabricated with standard lithography. The resulting '2.5D' whispering-gallery mode resonators store 98% of their energy in vacuum. We have measured internal quality factors above 3 million at the single photon level and have used the device as a materials characterization platform to place an upper bound on the surface resistance of thin film aluminum of less than 250nOhms.