Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hitting a BEC with a comb: Evolution of interference patterns inside a
  magnetic trap   We study the evolution inside a harmonic trap of Bose-Einstein condensates
released from the periodic potential of an optical lattice. After a
time-of-flight, harmonic motion of the interference peaks is observed as well
as a breathing motion in the direction perpendicular to the optical lattice. We
interpret these results in terms of a simple physical model and discuss the
possibility of more detailed studies of such a system.

22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys