Realization of bichromatic optical superlattices

Abstract

We present the experimental realization of optical superlattices created by exposing laser cooled ${}^{85}\mathrm{Rb}$ atoms to a bichromatic standing-wave light field. The two light frequencies are tuned close to the ${D}_{1}$ and ${D}_{2}$ lines of ${}^{85}\mathrm{Rb}.$ The total optical potential seen by the atoms exhibits a modulation at the spatial beat period of the two light fields in addition to the typical periodicity on the scale of an optical wavelength. The bichromatic light field cools the atoms into the superlattice potential, resulting in a density modulation on a macroscopic scale. We have observed the density modulation directly in one- and three-dimensional superlattice configurations using an absorption imaging technique.