Storage of fiber-guided light in a nanofiber-trapped ensemble of cold atoms

Tapered optical fibers with a nanofiber waist are versatile light-matter interfaces. Of particular interest are laser-cooled atoms trapped in the evanescent field surrounding the optical nanofiber: they exhibit both long ground-state coherence times and efficient coupling to fiber-guided fields. Here, we demonstrate electromagnetically induced transparency, slow light, and the storage of fiber-guided optical pulses in an ensemble of cold atoms trapped in a nanofiber-based optical lattice. We measure group velocities of 50 m/s. Moreover, we store optical pulses at the single-photon level and retrieve them on demand in the fiber after 2 mu s with an overall efficiency of (3.0 +/- 0.4) %. Our results show that nanofiber-based interfaces for cold atoms have great potential for the realization of building blocks for future optical quantum information networks. (C) 2015 Optical Society of America