Ultra-cold atoms confined to optical lattices are a unique condensed matter system. I will discuss the case of 2D Bose systems, where the atoms are free to move in two directions, but strongly confined in the third.

Bose-condensed rubidium atoms are loaded into a 3D optical lattice with an average occupancy of one atom per-site. An ensemble of 2D lattice systems are realized when one direction of the 3D lattice is much deeper than the remaining two. These 2D systems exhibit a superfluid-insulator transition as the lattice depth (in the remaining 2 directions) is increased. I present new measurements that show that the conventional signature of long-range order, namely diffraction, disappears continuously as the Mott state develops, likewise the coherence-length continuously decreases. We also probe this transition via correlations in atom shot noise, which are sensitive only to atoms in the Mott state.

Last updated on Tuesday, 11 April 2006 by Victor Yakovenko