Radio-frequency-modulated Rydberg states in a vapor cell

TL;DR

This paper demonstrates the use of rubidium Rydberg atoms in a vapor cell as sensors for strong RF electric fields, employing electromagnetically induced transparency and Floquet theory for precise measurements and analysis.

Contribution

It introduces a method for measuring strong RF fields using Rydberg atoms with detailed spectroscopic analysis and theoretical modeling of level modulation.

Findings

Rydberg levels exhibit Stark shifts and sidebands under RF modulation.

High fields cause intersection with hydrogenic manifolds, enabling precision measurements.

Floquet theory accurately describes strong-field level behavior.

Abstract

We measure strong radio-frequency (RF) electric fields using rubidium Rydberg atoms prepared in a room-temperature vapor cell as field sensors. Electromagnetically induced transparency is employed as an optical readout. We RF-modulate the 60$S_{1/2}$ and 58$D_{5/2}$ Rydberg states with 50~MHz and 100~MHz fields, respectively. For weak to moderate RF fields, the Rydberg levels become Stark-shifted, and sidebands appear at even multiples of the driving frequency. In high fields, the adjacent hydrogenic manifold begins to intersect the shifted levels, providing rich spectroscopic structure suitable for precision field measurements. A quantitative description of strong-field level modulation and mixing of $S$ and $D$ states with hydrogenic states is provided by Floquet theory. Additionally, we estimate the shielding of DC electric fields in the interior of the glass vapor cell.