Optical trap for an atom around the midpoint between two coupled identical parallel optical nanofibers

Fam Le Kien,Síle Nic Chormaic,Thomas Busch

doi:10.1103/physreva.103.063106

Abstract

We study the trapping of a ground-state cesium atom in a small region around the midpoint between two coupled identical parallel optical nanofibers. We suggest to use a blue-detuned guided light field in the odd $\mathcal{E}_z$-sine array mode to produce an optical potential with a local minimum of exact zero at the midpoint between the nanofibers. We find that the effects of the van der Waals potential on the total trapping potential around the minimum point are not significant when the fiber separation distance and the power of the guided light field are large. For appropriate realistic parameters, a net trapping potential with a significant depth of about 1 mK, a large coherence time of several seconds, and a large recoil-heating-limited trap lifetime of several hours can be obtained. We investigate the dependencies of the trapping potential on the power of the guided light field, the fiber radius, the wavelength of light, and the fiber separation distance.

Highlights

Optical nanofibers are tapered fibers with a subwavelength diameter and significantly differing core and cladding refractive indices [1]
We have studied the trapping potential of a ground-state cesium atom in a small region around the midpoint between two coupled identical parallel optical nanofibers
We have suggested to use a blue-detuned guided light field in the odd Ez-sine array mode of the two nanofibers to produce an optical potential with a local minimum at the midpoint between the nanofibers

Summary

INTRODUCTION

Optical nanofibers are tapered fibers with a subwavelength diameter and significantly differing core and cladding refractive indices [1]. A successful technique for trapping atoms near a nanofiber is to combine optical dipole forces of a blue- and a reddetuned guided light field [5,6]. It has been shown that the distribution of the field intensity in the odd Ez-sine array mode has a local minimum of exactly zero at the midpoint between the nanofibers [40] This feature can be used to trap atoms with a single blue-detuned light field. We study the possibility of trapping a groundstate cesium atom in a small region around the midpoint between two coupled identical parallel optical nanofibers.

ODD Ez-SINE ARRAY MODE OF TWO IDENTICAL PARALLEL NANOFIBERS

TRAPPING POTENTIAL OF AN ATOM OUTSIDE THE NANOFIBERS

Total potential

SUMMARY