Spatial period doubling in Bose-Einstein condensates in an optical lattice
Abstract
We demonstrate that there exist stationary states of Bose-Einstein condensates in an optical lattice that do not satisfy the usual Bloch periodicity condition. Using the discrete model appropriate to the tight-binding limit we determine energy bands for period-doubled states in a one-dimensional lattice. In a complementary approach we calculate the band structure from the Gross-Pitaevskii 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 period-doubled states with the same energy. The period-doubled 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:cond-mat/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 Bose-Einstein condensates in periodic potentials solitons vortices and topological excitations;
- Solitons;
- Condensed Matter - Soft Condensed Matter
- E-Print:
- 4 pages, 3 figures, change of content