Period-Doubled Bloch States in a Bose–Einstein Condensate
Bao-Guo Yang1 , Peng-Ju Tang1 , Xin-Xin Guo1 , Xu-Zong Chen1 , Biao Wu2** , Xiao-Ji Zhou1**
1 School of Electronics Engineering and Computer Science, Peking University, Beijing 1008712 International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871
Abstract ：We study systematically the period-doubled Bloch states for a weakly interacting Bose–Einstein condensate in a one-dimensional optical lattice. This kind of state is of form $\psi_k=e^{ikx}\phi_k(x)$, where $\phi_k(x)$ is of a period twice the optical lattice constant. Our numerical results show how these nonlinear period-doubled states grow out of linear period-doubled states at a quarter away from the Brillouin zone center as the repulsive interatomic interaction increases. This is corroborated by our analytical results. We find that all nonlinear period-doubled Bloch states have both Landau instability and dynamical instability.
收稿日期: 2018-05-02
出版日期: 2018-06-24
:
03.75.Lm
(Tunneling, Josephson effect, Bose-Einstein condensates in periodic potentials, solitons, vortices, and topological excitations)
67.85.Hj
(Bose-Einstein condensates in optical potentials)
67.85.Bc
(Static properties of condensates)
67.85.De
(Dynamic properties of condensates; excitations, and superfluid flow)
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2018, Vol. 35 
