Spatial period doubling in BoseEinstein condensates in an optical lattice
Abstract
We demonstrate that there exist stationary states of BoseEinstein condensates in an optical lattice that do not satisfy the usual Bloch periodicity condition. Using the discrete model appropriate to the tightbinding limit we determine energy bands for perioddoubled states in a onedimensional lattice. In a complementary approach we calculate the band structure from the GrossPitaevskii equation, considering both states of the usual Bloch form and states which have the Bloch form for a period equal to twice that of the optical lattice. We show that the onset of dynamical instability of states of the usual Bloch form coincides with the occurrence of perioddoubled states with the same energy. The perioddoubled states are shown to be related to periodic trains of solitons.
 Publication:

Physical Review A
 Pub Date:
 April 2004
 DOI:
 10.1103/PhysRevA.69.043604
 arXiv:
 arXiv:condmat/0307183
 Bibcode:
 2004PhRvA..69d3604M
 Keywords:

 03.75.Kk;
 03.75.Lm;
 05.45.Yv;
 Dynamic properties of condensates;
 collective and hydrodynamic excitations superfluid flow;
 Tunneling Josephson effect BoseEinstein condensates in periodic potentials solitons vortices and topological excitations;
 Solitons;
 Condensed Matter  Soft Condensed Matter
 EPrint:
 4 pages, 3 figures, change of content