Strong light shifts from near-resonant and polychromatic fields: comparison of Floquet theory and experiment

TL;DR

This paper develops a non-perturbative numerical method to calculate strong light shifts in atoms caused by multiple optical fields and confirms its accuracy through experiments with cold rubidium atoms, showing good agreement with theory.

Contribution

The paper introduces a novel non-perturbative numerical technique for calculating strong light shifts in atoms under complex optical field conditions, validated by experimental spectroscopy.

Findings

The numerical method accurately predicts light-induced level shifts.

Experimental results agree with theoretical predictions.

Strong nonlinear shifts observed at high light intensities.

Abstract

We present a non-perturbative numerical technique for calculating strong light shifts in atoms under the influence of multiple optical fields with arbitrary polarization. We confirm our technique experimentally by performing spectroscopy of a cloud of cold $^{87}$Rb atoms subjected to $\sim$ kW/cm$^2$ intensities of light at 1560.492 nm simultaneous with 1529.269 nm or 1529.282 nm. In these conditions the excited state resonances at 1529.26 nm and 1529.36 nm induce strong level mixing and the shifts are highly nonlinear. By absorption spectroscopy, we observe that the induced shifts of the 5P3/2 hyperfine Zeeman sublevels agree well with our theoretical predictions.. We propose the application of our theory and experiment to accurate measurements of excited-state electric-dipole matrix elements.