Resolving magnetic-sublevel structure in Rydberg Autler-Townes spectra with arbitrary RF polarization

TL;DR

This paper demonstrates how elliptical RF polarization affects magnetic sublevel coupling in Rydberg atoms, leading to complex Autler-Townes spectra, and provides a comprehensive theoretical and experimental framework for understanding these effects.

Contribution

The authors develop a full multi-level Hamiltonian model that accounts for arbitrary RF polarization, explaining previously unexplained spectral features in Rydberg Autler-Townes spectra.

Findings

Spectral features depend on RF ellipticity and magnetic sublevel coupling.

Resolved multiple peaks in spectra match theoretical predictions.

Homogeneous RF fields enable complete resolution of dressed states.

Abstract

We investigate the role of magnetic sublevels in Autler-Townes spectra of Rydberg atoms driven by radio-frequency (RF) fields with arbitrary polarization. While conventional treatments predict two symmetric sidebands from independent mJ transitions, experiments have reported additional unexplained spectral features. We show that these arise from elliptical RF polarization, which coherently couples multiple magnetic sublevels and requires a full multi-level treatment. We develop and diagonalize a Hamiltonian including all coupled mJ sublevels, predicting polarization-dependent degeneracies that produce two, three, or four resolved peaks. Using long-wavelength transitions and an anechoic environment we realize homogeneous RF fields that for the first time enable complete resolution of the mJ-dependent dressed states. We observe excellent agreement with theory as the RF ellipticity is varied. These results demonstrate that RF polarization fundamentally modifies Autler-Townes spectra and provide a consistent framework for interpreting magnetic-sublevel structure, with implications for Rydberg-based RF electrometry and polarimetry.