Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlinear Schrodinger equations with a multiple-well potential and a
  Stark-type perturbation   A Bose-Einstein condensate (BEC) confined in a one-dimensional lattice under
the effect of an external homogeneous field is described by the
Gross-Pitaevskii equation. Here we prove that such an equation can be reduced,
in the semiclassical limit and in the case of a lattice with a finite number of
wells, to a finite-dimensional discrete nonlinear Schrodinger equation. Then,
by means of numerical experiments we show that the BEC's center of mass
exhibits an oscillating behavior with modulated amplitude; in particular, we
show that the oscillating period actually depends on the shape of the initial
wavefunction of the condensate as well as on the strength of the nonlinear
term. This fact opens a question concerning the validity of a method proposed
for the determination of the gravitational constant by means of the measurement
of the oscillating period.

32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat
6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph