arXiv:1001.4667 · Physical Review A
Symmetry breaking in a localized interacting binary Bose-Einstein condensate in a bichromatic optical lattice
Yongshan Cheng, Sadhan K. Adhikari
Abstract
By direct numerical simulation of the time-dependent Gross-Pitaevskii equation using the split-step Fourier spectral method, we study different aspects of the localization of a cigar-shaped interacting binary (two-component) Bose-Einstein condensate (BEC) in a one-dimensional bichromatic quasiperiodic optical-lattice potential, as used in a recent experiment on the localization of a BEC [Roati et al., Nature 453, 895 (2008)]. We consider two types of localized states: (i) when both localized components have a maximum of density at the origin $x=0$, and (ii) when the first component has a maximum of density and the second a minimum of density at $x=0$. In the noninteracting case, the density profiles are symmetric around $x=0$. We numerically study the breakdown of this symmetry due to interspecies and intraspecies interactions acting on the two components. Where possible, we have compared the numerical results with a time-dependent variational analysis. We also demonstrate the stability of the localized symmetry-broken BEC states under small perturbation.