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Loop structure of the lowest Bloch band for a Bose-Einstein condensate

Dmitri Diakonov·L. M. Jensen·C. J. Pethick·H. Smith
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Abstract

We investigate analytically and numerically Bloch waves for a Bose--Einstein condensate in a sinusoidal external potential. At low densities the dependence of the energy on the quasimomentum is similar to that for a single particle, but at densities greater than a critical one the lowest band becomes triple-valued near the boundary of the first Brillouin zone and develops the structure characteristic of the swallow-tail catastrophe. We comment on the experimental consequences of this behavior.

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Dmitri Diakonov, L. M. Jensen, C. J. Pethick, H. Smith. 2001-11-16. Loop structure of the lowest Bloch band for a Bose-Einstein condensate. https://doi.org/10.1103/physreva.66.013604

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