Demonstration of a State-Insensitive, Compensated Nanofiber Trap

Abstract

We report the experimental realization of an optical trap that localizes single Cs atoms $\ensuremath{\simeq}215\text{ }\text{ }\mathrm{nm}$ from the surface of a dielectric nanofiber. By operating at magic wavelengths for pairs of counterpropagating red- and blue-detuned trapping beams, differential scalar light shifts are eliminated, and vector shifts are suppressed by $\ensuremath{\approx}250$. We thereby measure an absorption linewidth $\ensuremath{\Gamma}/2\ensuremath{\pi}=5.7\ifmmode\pm\else\textpm\fi{}0.1\text{ }\text{ }\mathrm{MHz}$ for the Cs $6{S}_{1/2}$, $F=4\ensuremath{\rightarrow}6{P}_{3/2}$, ${F}^{\ensuremath{'}}=5$ transition, where ${\ensuremath{\Gamma}}_{0}/2\ensuremath{\pi}=5.2\text{ }\text{ }\mathrm{MHz}$ in free space. An optical depth $d\ensuremath{\simeq}66$ is observed, corresponding to an optical depth per atom ${d}_{1}\ensuremath{\simeq}0.08$. These advances provide an important capability for the implementation of functional quantum optical networks and precision atomic spectroscopy near dielectric surfaces.