Manipulation of coherent atom waves using accelerated two-dimensional optical lattices

We study the dynamics of Bose-Einstein condensates in accelerated two-dimensional (2D) optical square lattices by numerically solving the Gross-Pitaevskii equation. We consider the regime with negligible mean-field interactions and examine in detail the pulses of atom clouds ejected from the condensate due to Landau-Zener tunnelling. The pulses exhibit patterned structures that can be understood from the momentum-space dynamics of the condensate. Apart from conceiving the realization of a pulsed 2D atom laser, we demonstrate that, by exploring the band structure of the lattice, the Landau-Zener tunnelling and Bragg reflection of the condensate inside the optical lattice can provide a means of manipulation of coherent atom waves.