Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin relaxation and band excitation of a dipolar BEC in 2D optical
  lattices   We observe interband transitions mediated by the dipole-dipole interaction
for an array of 1D quantum gases of chromium atoms, trapped in a 2D optical
lattice. Interband transitions occur when dipolar relaxation releases an energy
which matches or overcomes the lattice band gap. We analyze the role of
tunneling in higher lattice bands on this process. We compare the experimental
dipolar relaxation rate with a calculation based on a multiple Fermi Golden
Rule approach, when the lattice sites are symmetric, and the magnetic field is
parallel to the lattice axis. We also show that an almost complete suppression
of dipolar relaxation is obtained below a magnetic field threshold set by the
depth of the lattice: 1D quantum gases in an excited Zeeman state then become
metastable.

1
The categories of this paper are: cs
3
The categories of this paper are: physics
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph