Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Entanglement in atomic systems interacting with single-photon pulses in
  free space   New technologies providing tight focusing lens and mirrors with large
numerical apertures and electro-optic modulation of single photons are now
available for the investigation of photon-atom interactions without a cavity.
From the theoretical side, new models must be developed which take into account
the intrinsic open system aspect of the problem as well as details about atomic
relative positions and temporal (spectral) features of the pulses. In this
paper, we investigate the generation of nonclassical correlations between two
atoms in free space interacting with a quantized pulse containing just one
single photon. For this purpose, we develop a general theoretical approach
which allows us to find the equations of motion for single- and two-body atomic
operators from which we obtained the system density operator. We show that one
single photon is capable of promoting substantial entanglement between two
initially ground state atoms, and we analyze the dependence of these
correlations on atomic relative positions (vacuum effects) and spectral
features of the single photon pulse.

31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph