2003/12/31 by Artem M. Dudarev, Roberto B. Diener, Qian Niu
Physics and Astronomy · #cond-mat.soft
paper · pdf · doi:10.1088/1464-4266/6/5/010
published as J. Opt. B: Quantum Semiclass. Opt. 6 (May 2004) S231-S240 · 16 subfigures, v2: added a section on delocalization and references
arxiv created 2004/02/21 · arxiv updated 2009/12/01
We suggest a method to experimentally obtain two-dimensional matter-wave discrete solitons with a \it self-repulsive BEC in optical lattices. At the edge of the Brillouin zone, a wave packet effective mass is negative which could be treated as inversion of the nonlinearity sign. Above critical nonlinearity this makes the wave packets collapse partially into localized modes with a chemical potential located in the gap between the first and the second bands. This critical nonlinearity is also associated with the smallest nonlinearity for which the discrete solitons are possible in the gap. Extensive numerical simulations for square and asymmetric honeycomb lattices in continuous model illustrate every stage of the process.