Optical measurements of strong microwave fields with Rydberg atoms in a vapor cell

TL;DR

This paper demonstrates a method to measure strong microwave electric fields using Rydberg atoms in a vapor cell through spectral analysis of electromagnetically induced transparency, achieving high precision in field measurement.

Contribution

The study introduces an all-optical technique employing Rydberg atom spectroscopy and Floquet modeling for precise measurement of high-power microwave fields in a vapor cell.

Findings

Achieved an electric field measurement precision of 6%.

Modeled Rydberg level energies with Floquet theory showing excellent agreement.

Demonstrated optical detection of microwave fields up to 230V/m.

Abstract

We present a spectral analysis of Rydberg atoms in strong microwave fields using electromagnetically induced transparency (EIT) as an all-optical readout. The measured spectroscopic response enables optical, atom-based electric field measurements of high-power microwaves. In our experiments, microwaves are irradiated into a room-temperature rubidium vapor cell. The microwaves are tuned near the two-photon 65D-66D Rydberg transition and reach an electric field strength of 230V/m, about 20% of the microwave ionization threshold of these atoms. A Floquet treatment is used to model the Rydberg level energies and their excitation rates. We arrive at an empirical model for the field-strength distribution inside the spectroscopic cell that yields excellent overall agreement between the measured and calculated Rydberg EIT-Floquet spectra. Using spectral features in the Floquet maps we achieve an absolute strong-field measurement precision of 6%.