A tapered optical nanofiber simultaneously used to trap and optically
interface of cold atoms through evanescent fields constitutes a new and well
controllable hybrid quantum system. The atoms are trapped in two parallel 1D
optical lattices generated by suitable far blue and red detuned evanescent
field modes very close to opposite sides of the nanofiber surface. Collective
electronic excitations (excitons) of each of the optical lattices are
resonantly coupled to the second lattice forming symmetric and antisymmetric
common excitons. In contrast to the inverse cube dependence of the individual
atomic dipole-dipole interaction, we analytically find an exponentially
decaying coupling strength with distance between the lattices. The resulting
symmetric (bright) excitons strongly interact with the resonant nanofiber
photons to form fiber polaritons, which can be observed through linear optical
spectra. For large enough wave vectors the polariton decay rate to free space
is strongly reduced, which should render this system ideal for the realization
of long range quantum communication between atomic ensembles.Comment: 9 pages, 9 figure