Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Matter-wave gap solitons in atomic bandgap structures   We demonstrate that a Bose-Einstein condensate in an optical lattice forms a
reconfigurable matter-wave structure with a band-gap spectrum, which resembles
a nonlinear photonic crystal for light waves. We study in detail the case of a
two-dimensional square optical lattice and show that this atomic bandgap
structure allows nonlinear localization of atomic Bloch waves in the form of
two-dimensional matter-wave gap solitons.

17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
3
The categories of this paper are: physics
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th