Coupling Rydberg atoms to microwave fields in a superconducting coplanar waveguide resonator

TL;DR

This study demonstrates the coupling of Rydberg helium atoms to microwave fields within a superconducting coplanar waveguide resonator, enabling detailed investigation of atom-resonator interactions at cryogenic temperatures.

Contribution

It introduces a novel experimental setup for coupling Rydberg atoms to superconducting microwave resonators and explores their coherent interactions.

Findings

Successful coupling of Rydberg helium atoms to microwave fields in a superconducting resonator

Observation of Rabi oscillations indicating coherent atom-resonator interactions

Effective state detection via pulsed electric field ionization

Abstract

Rydberg helium atoms traveling in pulsed supersonic beams have been coupled to microwave fields in a superconducting coplanar waveguide (CPW) resonator. The atoms were initially prepared in the 1s55s $^3$S$_1$ Rydberg level by two-color two-photon laser excitation from the metastable 1s2s $^3$S$_1$ level. Two-photon microwave transitions between the 1s55s $^3$S$_1$ and 1s56s $^3$S$_1$ levels were then driven by the 19.556 GHz third-harmonic microwave field in a quarter-wave CPW resonator. This superconducting microwave resonator was fabricated from niobium nitride on a silicon substrate and operated at temperatures between 3.65 and 4.30 K. The populations of the Rydberg levels in the experiments were determined by state-selective pulsed electric field ionization. The coherence of the atom-resonator coupling was studied by time-domain measurements of Rabi oscillations.