  We propose a scheme for producing directed motion in a lattice system by
applying a periodic driving potential. By controlling the dynamics by means of
the effect known as coherent destruction of tunneling, we demonstrate a novel
ratchet-like effect that enables particles to be coherently manipulated and
steered without requiring local control. Entanglement between particles can
also be controllably generated, which points to the attractive possibility of
using these technique for quantum information processing.
