Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cavity Opto-Mechanics with a Bose-Einstein Condensate   Cavity opto-mechanics studies the coupling between a mechanical oscillator
and a cavity field, with the aim to shed light on the border between classical
and quantum physics. Here we report on a cavity opto-mechanical system in which
a collective density excitation of a Bose-Einstein condensate is shown to serve
as the mechanical oscillator coupled to the cavity field. We observe that a few
photons inside the ultrahigh-finesse cavity trigger a strongly driven
back-action dynamics, in quantitative agreement with a cavity opto-mechanical
model. With this experiment we approach the strong coupling regime of cavity
opto-mechanics, where a single excitation of the mechanical oscillator
significantly influences the cavity field. The work opens up new directions to
investigate mechanical oscillators in the quantum regime and quantum gases with
non-local coupling.

8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn