Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Trapping of Rb atoms by ac electric fields   We demonstrate trapping of an ultracold gas of neutral atoms in a macroscopic
ac electric trap. Three-dimensional confinement is obtained by switching
between two saddle-point configurations of the electric field. Stable trapping
is observed in a narrow range of switching frequencies around 60 Hz. The
dynamic confinement of the atoms is directly visualized at different phases of
the ac switching cycle. We observe about 10^5 Rb atoms in the 1 mm^3 large and
several microkelvins deep trap with a lifetime of approximately 5 s.

27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an