Physical Review A
Spatially localized structures and oscillons in atomic Bose-Einstein condensates confined in optical lattices
M. V. Charukhchyan, Evgeny S. Sedov, Sergei M Arakelyan, A. P. Alodjants
Abstract
We consider the problem of formation of small-amplitude spatially localized oscillatory structures for atomic Bose-Einstein condensates confined in two- and three-dimensional optical lattices, respectively. Our approach is based on applying the regions with different signs of atomic effective masses where an atomic system exhibits effective hyperbolic dispersion within the first Brillouin zone. By using the $\mathbf{kp}$ method we have demonstrated mapping of the initial Gross-Pitaevskii equation on nonlinear Klein-Gordon and/or Ginzburg-Landau-Higgs equations, which is inherent in matter fields within ${\ensuremath{\phi}}^{4}$-field theories. Formation of breatherlike oscillating localized states---atomic oscillons---as well as kink-shaped states have been predicted in this case. Apart from classical field theories atomic field oscillons occurring in finite lattice structures possess a critical number of particles for their formation. The obtained results pave the way to simulating some analogues of fundamental cosmological processes occurring during our Universe's evolution and to modeling nonlinear hyperbolic metamaterials with condensed matter (atomic) systems.