Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Entanglement of a Mesoscopic Field with an Atom induced by Photon
  Graininess in a Cavity   We observe that a mesoscopic field made of several tens of microwave photons
exhibits quantum features when interacting with a single Rydberg atom in a
high-Q cavity. The field is split into two components whose phases differ by an
angle inversely proportional to the square root of the average photon number.
The field and the atomic dipole are phase-entangled. These manifestations of
photon graininess vanish at the classical limit. This experiment opens the way
to studies of large Schrodinger cat states at the quantum-classical boundary.

37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
19
The categories of this paper are: eess
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph