Stability of Bose-Einstein Condensates in a Kronig-Penney Potential

Published

October 16, 2008

Author(s)

Ippei Danshita, S Tsuchiya

Abstract

We study the stability of Bose-Einstein condensates with superfluid currents in a one-dimensional periodic potential. By using the Kronig-Penney model, the condensate and Bogoliubov bands are analytically calculated and the stability of condensates in a periodic potential is discussed. The Landau and dynamical instabilities occur in a Kronig-Penney potential when the quasimomentum of the condensate exceeds certain critical values as in a sinusoidal potential. It is found that the onsets of the Landau and dynamical instabilities coincide with the point where the perfect transmission of low energy excitations through eachpotential barrier is forbidden. The Landau instability is caused by the excitations with small $q$ and the dynamical instability is caused by the excitations with $q=\pi/a$ at their onsets, where $q$ is the quasimomentum of excitation and $a$ is the lattice constant. A swallow-tail energy loop appears at the edge of the first condensate band when the mean-field energy is sufficiently larger than the strength of the periodic potential. We find that

Citation

Physical Review A (Atomic, Molecular and Optical Physics)

Pub Type

Journals

Keywords

Bogoliubov equations, Bose-Einstein condensation, Kronig-Penney, optical lattice

Citation

Danshita, I. and Tsuchiya, S. (2008), Stability of Bose-Einstein Condensates in a Kronig-Penney Potential, Physical Review A (Atomic, Molecular and Optical Physics) (Accessed April 19, 2024)