Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Single photon absorption by a single atom: from heralded absorption to
  polarization state mapping   Together with photon emission, the absorption of a single photon by a single
atom is a fundamental process in matter-light interaction that manifests its
quantum mechanical nature. As an experimentally controlled process, it is a key
tool for the realization of quantum technologies. In particular, in an
atom/photon based quantum network scenario, in which localized atomic particles
are used as quantum information processing nodes while photons are used as
carriers of quantum information between distant nodes, controlling both
emission and absorption of single photons by single atoms is required for
quantum coherent state mapping between the two entities. Most experimental
efforts to date have focused on establishing the control of single photon
emission by single trapped atoms, and the implementation of quantum networking
protocols using this interaction. In this chapter, we describe experimental
efforts to control the process of single photon absorption by single trapped
ions. We describe a series of experiments in which polarization entangled
photon pairs, generated by a spontaneous parametric down-conversion source, are
coupled to a single ion. First the source is operated to generate heralded
single photons, and coincidences between the absorption event of one photon of
the pair and the detection of the heralding partner photon are observed. We
then show how polarization control in the process is established, leading to
the manifestation of the photonic polarization entanglement in the absorption
process. Finally, we introduce protocols in which this interaction scheme is
harnessed to perform tasks in a quantum network, such as entanglement
distribution among distant nodes of the network, and we demonstrate a specific
protocol for heralded, high-fidelity photon-to-atom quantum state transfer.

5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics