Inhomogeneous broadening of optical transitions of 87Rb atoms in an optical nanofiber trap

TL;DR

This study demonstrates optical trapping of 87Rb atoms around a nanofiber and models the resulting broadening of their absorption profile due to vector light shifts, providing insights into atom-light interactions in nanofiber traps.

Contribution

The paper introduces a comprehensive model including scalar, vector, and tensor light shifts to explain absorption broadening in 87Rb nanofiber traps, advancing understanding of atom-light interactions.

Findings

Vector light shifts cause asymmetric absorption profiles.

The model accurately predicts broadening based on atom temperature and position.

The approach enables estimation of atom numbers in the trap.

Abstract

We experimentally demonstrate optical trapping of 87Rb atoms using a two-color evanescent field around an optical nanofiber. In our trapping geometry, a blue-detuned traveling wave whose polarization is nearly parallel to the polarization of a red-detuned standing wave produces significant vector light shifts that lead to broadening of the absorption profile of a near-resonant beam at the trapping site. A model that includes scalar, vector, and tensor light shifts of the probe transition $5S_{1/2}$-$5P_{3/2}$ from the trapping beams, weighted by the temperature-dependent position of the atoms in the trap, qualitatively describes the observed asymmetric profile and explains differences with previous experiments that used Cs atoms. The model provides a consistent way to extract the number of atoms in the trap.