Abdelâali Boudjemaâ, G. V. Shlyapnikov
We discuss fluctuations in a dilute two-dimensional Bose-condensed dipolar gas, which has a roton-maxon character of the excitation spectrum. We calculate the density-density correlation function, fluctuation corrections to the chemical potential, compressibility, and the normal (superfluid) fraction. It is shown that the presence of the roton strongly enhances fluctuations of the density, and we establish the validity criterion of the Bogoliubov approach. At zero temperature the condensate depletion becomes significant if the roton minimum is sufficiently close to zero. At finite temperatures exceeding the roton energy and the interaction between particles, the effect of thermal fluctuations is stronger and it may lead to a large normal fraction of the gas.
View original:
http://arxiv.org/abs/1212.1136
No comments:
Post a Comment