Demonstration of a state-insensitive, compensated nanofiber trap

Abstract

We report the experimental realization of an optical trap that localizes single Cs atoms ≃ 215 nm from surface of a dielectric nanober. By operating at magic wavelengths for pairs of counterpropagating red- and blue-detuned trapping beams, dierential scalar light shifts are eliminated, and vector shifts are suppressed by ≈ 250. We thereby measure an absorption linewidth Γ/2π = 5.7 ± 0.1 MHz for the Cs 6S_(1/2), F = 4 → 6P_(3/2), F' = 5 transition, where Γ_0/2π = 5.2 MHz in free space. Optical depth d ≃ 66 is observed, corresponding to an optical depth per atom d_1 ≃ 0.08. These advances provide an important capability for the implementation of functional quantum optical networks and precision atomic spectroscopy near dielectric surfaces.