Nonadiabatic loading of a Bose-Einstein condensate into the ground state of an optical lattice

We present a scheme for rapidly loading a Bose-Einstein condensate into a single Bloch state of a weak optical lattice at a quasimomentum of q=hk. Rabi cycling of the Bose-Einstein condensate between momentum states is modified by a phase shift applied to the lattice. By appropriately choosing the magnitude and timing of the phase shift, we demonstrate nearly perfect loading of the lattice ground state, the signature of which is an abrupt halt to the Rabi cycling.