Dipole force free optical control and cooling of nanofiber trapped atoms

TL;DR

This paper introduces a dipole force free optical scheme for controlling and cooling atoms near nanofibers, enabling prolonged trapping and independent manipulation of atomic states using guided light.

Contribution

It presents a novel dipole force free method for coupling and cooling atomic radial motion in nanofiber traps, achieving prolonged trap lifetime and independent control of atomic degrees of freedom.

Findings

Demonstrated all-optical coupling of cesium hyperfine states and motional sidebands.

Prolonged atomic trap lifetime via Raman sideband cooling of radial motion.

Achieved full control of internal and external atomic states with guided light.

Abstract

The evanescent field surrounding nano-scale optical waveguides offers an efficient interface between light and mesoscopic ensembles of neutral atoms. However, the thermal motion of trapped atoms, combined with the strong radial gradients of the guided light, leads to a time-modulated coupling between atoms and the light mode, thus giving rise to additional noise and motional dephasing of collective states. Here, we present a dipole force free scheme for coupling of the radial motional states, utilizing the strong intensity gradient of the guided mode and demonstrate all-optical coupling of the cesium hyperfine ground states and motional sideband transitions. We utilize this to prolong the trap lifetime of an atomic ensemble by Raman sideband cooling of the radial motion, which has not been demonstrated in nano-optical structures previously. Our work points towards full and independent control of internal and external atomic degrees of freedom using guided light modes only.