Radial and angular rotons in trapped dipolar gases
Statistical Mechanics
2009-11-11 v1
Abstract
We study Bose-Einstein condensates with purely dipolar interactions in oblate (pancake) traps. We find that the condensate always becomes unstable to collapse when the number of particles is sufficiently large. We analyze the instability, and find that it is the trapped-gas analogue of the ``roton-maxon'' instability previously reported for a gas that is unconfined in two dimensions. In addition, we find that under certain circumstances, the condensate wave function attains a biconcave shape, with its maximum density away from the center of the gas. These biconcave condensates become unstable due to azimuthl excitation - an angular roton.
Cite
@article{arxiv.cond-mat/0607704,
title = {Radial and angular rotons in trapped dipolar gases},
author = {Shai Ronen and Daniele C. E. Bortolotti and John. L. Bohn},
journal= {arXiv preprint arXiv:cond-mat/0607704},
year = {2009}
}
Comments
4 pages, 3 figures