Dynamical Bloch band suppression in an optical lattice

Summary form only given. We report the observation of dynamical suppression of Bloch bands due to an AC field. Our system consists of laser-cooled atoms in an optical lattice, rather than electrons in a superlattice. The main advantage of our system is the long coherence times, limited only by residual spontaneous scattering. In our experiment we trap neutral sodium atoms in the lowest band of a one-dimensional optical lattice. We then modulate the position of the potential to realize both an intense AC field and a weak spectroscopic probe in order to directly observe band suppression.