Coherent backscattering of light off one-dimensional atomic strings

We present the first experimental realization of coherent Bragg scattering off a one-dimensional (1D) system -- two strings of atoms strongly coupled to a single photonic mode -- realized by trapping atoms in the evanescent field of a tapered optical fiber (TOF), which also guides the probe light. We report nearly 12% power reflection from strings containing only about one thousand cesium atoms, an enhancement of two orders of magnitude compared to reflection from randomly positioned atoms. This result paves the road towards collective strong coupling in 1D atom-photon systems. Our approach also allows for a straightforward fiber connection between several distant 1D atomic crystals.