title: Dispersive optical interface based on nanofiber-trapped atoms.
abstract: We dispersively interface an ensemble of 1000 atoms trapped in the evanescent field surrounding a tapered optical nanofiber. This method relies on the azimuthally asymmetric coupling of the ensemble with the evanescent field of an off-resonant probe beam, transmitted through the nanofiber. The resulting birefringence and dispersion are significant; we observe a phase shift per atom of ∼1  mrad at a detuning of 6 times the natural linewidth, corresponding to an effective resonant optical density per atom of 0.027. Moreover, we utilize this strong dispersion to nondestructively determine the number of atoms.
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
authors.forename: S T
authors.initials: ST
authors.lastname: Dawkins
authors.forename: R
authors.initials: R
authors.lastname: Mitsch
authors.forename: D
authors.initials: D
authors.lastname: Reitz
authors.forename: E
authors.initials: E
authors.lastname: Vetsch
authors.forename: A
authors.initials: A
authors.lastname: Rauschenbeutel