Frequency modulation of Rydberg states by radio frequency electromagnetic fields

TL;DR

This paper demonstrates how radio-frequency electric fields can modulate Rydberg states in rubidium vapor, creating measurable sidebands in EIT signals that reveal the RF field's strength and atomic polarizability.

Contribution

It introduces a method to generate and analyze sidebands in Rydberg EIT signals caused by RF fields, enabling electric field measurement via Stark effect in thermal vapor.

Findings

Sidebands in EIT signals are generated by RF modulation of Rydberg states.

The sideband strength varies with RF voltage following a Bessel function pattern.

Atomic polarizability for the 54S1/2 state is estimated as 1.01×10^8 Hz/(V/cm)^2.

Abstract

In this work, we demonstrate the generation of sidebands in electromagnetically induced transparency (EIT) signal due to frequency modulation of Rydberg states in $^{87}\text{Rb}$ thermal vapor. An oscillating radio-frequency (RF) electric field generated through a pair of parallel-placed copper plates leads to modulation of the Rydberg state by virtue of Stark effect where the frequency and strength of the sidebands quantify the RF electric field present. The variation of the strength of the EIT peak and the sidebands with RF voltage is observed to vary as a function of the Bessel function of modulation index. It provides an estimate of the atomic polarizability in the medium, which for $54S_{1/2}$ state, is found to be $(h)\cdot1.01\times10^8$ $\text{Hz/(V/cm)}^2$.