Collapse and Revivals of Wave Packets in Optical Lattices

We study the effects of dispersion, tunneling, and dissipation on wave-packet oscillations resembling coherent states of atoms in optical lattices. The wave packets are prepared by suddenly shifting the lattice after equilibration of the atoms at the lattice sites. The atoms oscillate in the light-shift potential wells, which exert a force arising from photon redistribution between lattice beams. We measure the resultant periodic intensity exchange between the beams, obtaining information on the wave-packet evolution. We observe a strong impact of dissipation on the overall shape and the time of revivals, as well as a suppression of tunneling by weak magnetic fields.