Optical lattices populated by neutral atoms are a good candidate for storing quantum information. Normally, internal degrees of freedom such as the hyperfine state are used to create the basic information unit, the qubit. However, atoms also possess motional degrees of freedom; for example, the confinement of atoms in the lattice wells creates quantized vibrational states. These motional degrees of freedom are usually controlled by introducing time-dependent lattice potentials. Now, Förster et

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... l. use microwave fields to effect transitions between vibrational levels of opposite hyperfine states of Cs atoms. Atoms in the two hyperfine states are loaded into two lattices spatially offset from each other. This arrangement enables transitions between different vibrational states, but the probability depends on the overlap of the (offset) wave functions. If the lattice is deep, transitions only happen between neighboring, slightly offset wells; if it is shallow, the offset can be increased and the atom becomes delocalized. Effective initialization into the lowest vibrational state is achieved, and Rabi oscillations between arbitrary vibrational states are demonstrated. This approach may lead to full control of quantum transport, likely a necessity for processing quantum information in this system. -JS