Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Collective dynamics and expansion of a Bose-Einstein condensate in a
  random potential   We investigate the dynamics of a Bose-Einstein condensate in the presence of
a random potential created by optical speckles. We first consider the effect of
a weak disorder on the dipole and quadrupole collective oscillations, finding
uncorrelated frequency shifts of the two modes with respect to the pure
harmonic case. This behaviour, predicted by a sum rules approach, is confirmed
by the numerical solution of the Gross-Pitaevskii equation. Then we analyze the
role of disorder on the one-dimensional expansion in an optical guide,
discussing possible localization effects. Our theoretical analysis provides a
useful insight into the recent experiments performed at LENS [J. Lye et al.,
Phys. Rev. Lett. 95, 070401 (2005); C. Fort et al., cond-mat/0507144].

24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th