Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Demonstration of fold and cusp catastrophes in an atomic cloud reflected
  from an optical barrier in the presence of gravity   We experimentally demonstrate first-order (fold) and second-order (cusp)
catastrophes in the density of an atomic cloud reflected from an optical
barrier in the presence of gravity, and show their corresponding universal
asymptotic behavior. The cusp point enables robust, field-free refocusing of an
expanding atomic cloud with a wide velocity distribution. Specifically, the
density attained at the cusp point in our experiment reached 65% of the peak
density of the atoms in the trap prior to their release. We thereby add
caustics to the various phenomena with parallels in optics that can be
harnessed for manipulation of cold atoms. The structural stability of
catastrophes provides inherent robustness against variations in the system's
dynamics and initial conditions, making them suitable for manipulation of atoms
under imperfect conditions and limited controllability.

20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess