# Robust field-dressed spectra of diatomics in an optical lattice

## TL;DR

This study investigates the absorption spectra of Na2 molecules in an optical lattice, revealing a surprisingly robust spectrum insensitive to the dressing field, with subtle signatures of light-induced conical intersections emerging under certain conditions.

## Contribution

It demonstrates the robustness of the absorption spectrum of diatomic molecules in an optical lattice despite the presence of light-induced conical intersections and explores conditions where their signatures appear.

## Key findings

- Spectra are insensitive to dressing field intensity and wavelength.
- LICI signatures are subtle and require artificial broadening to be observed.
- The absorption spectrum remains robust despite nonadiabatic phenomena.

## Abstract

The absorption spectra of the cold Na2 molecule dressed by a linearly polarized standing laser wave is investigated. In the studied scenario the rotational motion of the molecules is frozen while the vibrational and translational degrees of freedom are accounted for as dynamical variables. In such a situation a light-induced conical intersection (LICI) can be formed. To measure the spectra a weak field is used whose propagation direction is perpendicular to the direction of the dressing field but has identical polarization direction. Although LICIs are present in our model, the simulations demonstrate a very robust absorption spectrum, which is insensitive to the intensity and the wavelength of the dressing field and which does not reflect clear signatures of light-induced nonadiabatic phenomena related to the strong mixing between the electronic, vibration and translational motions. However, by widening artificially the very narrow translational energy level gaps, the fingerprint of the LICI appears to some extent in the spectrum.