Theory of elementary excitations in unstable Bose-Einstein condensates
Soft Condensed Matter
2007-05-23 v1
Abstract
Like classical fluids, quantum gases may suffer from hydrodynamic instabilities. Our paper develops a quantum version of the classical stability analysis in fluids, the Bogoliubov theory of elementary excitations in unstable Bose-Einstein condensates. In unstable condensates the excitation modes have complex frequencies. We derive the normalization conditions for unstable modes such that they can serve in a mode decomposition of the non-condensed component. Furthermore, we develop approximative techniques to determine the spectrum and the mode functions. Finally, we apply our theory to a sonic white hole and find that the spectrum of unstable modes is intrinsically discrete.
Keywords
Cite
@article{arxiv.cond-mat/0211462,
title = {Theory of elementary excitations in unstable Bose-Einstein condensates},
author = {U. Leonhardt and T. Kiss and P. Ohberg},
journal= {arXiv preprint arXiv:cond-mat/0211462},
year = {2007}
}