Optimized Coplanar Waveguide Resonators for a Superconductor-Atom Interface

TL;DR

This paper presents the design and characterization of superconducting coplanar waveguide resonators optimized for strong coupling with trapped Rydberg atoms, enabling advances in superconductor-atom quantum interfaces.

Contribution

It introduces a novel resonator design with high quality factors and enhanced electric fields, facilitating strong coupling in superconductor-atom hybrid systems.

Findings

Resonator quality factors above 10^4 at 4.2 K

Incorporation of copper electrodes enhances electric fields

Design enables strong coupling in cavity QED

Abstract

We describe the design and characterization of superconducting coplanar waveguide cavities tailored to facilitate strong coupling between superconducting quantum circuits and single trapped Rydberg atoms. For initial superconductor-atom experiments at 4.2 K, we show that resonator quality factors above $10^4$ can be readily achieved. Furthermore, we demonstrate that the incorporation of thick-film copper electrodes at a voltage antinode of the resonator provides a route to enhance the zero-point electric fields of the resonator in a trapping region that is 40 $\mu$m above the chip surface, thereby minimizing chip heating from scattered trap light. The combination of high resonator quality factor and strong electric dipole coupling between the resonator and the atom should make it possible to achieve the strong coupling limit of cavity quantum electrodynamics with this system.