Instabilities of a Bose-Einstein condensate with mixed nonlinear and linear lattices

Bose-Einstein condensates (BECs) in periodic potentials generate interesting physics on the instabilities of Bloch states. The lowest-energy Bloch states of BECs in pure nonlinear lattices are dynamically and Landau unstable, which breaks down BEC superfluidity. In this paper we propose to use an out-of-phase linear lattice to stabilize them. The stabilization mechanism is revealed by the averaged interaction. We further incorporate a constant interaction into BECs with mixed nonlinear and linear lattices and reveal its effect on the instabilities of Bloch states in the lowest band.

Automated summary

In this paper, a method to stabilize the Bloch states in BECs is proposed, which is achieved by using an out-of-phase linear lattice. The stabilization mechanism is explained through the averaged interaction. Furthermore, the effect of incorporating a constant interaction into BECs with mixed nonlinear and linear lattices on the instabilities of Bloch states in the lowest band is revealed.