Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlocal photon correlations and violation of Bell inequalities for
  spatially separated classical light fields   It is theoretically and experimentally shown that photons emitted by
statistically independent incoherent classical light sources and measured in
the far field in spatially separated modes may display spatial correlations
akin to path-entanglement of photons produced by quantum sources. By measuring
higher order photon-correlations at different locations, i.e., $m$ photons in
one mode and one photon in another mode, we experimentally demonstrate for $m
\geq 6$ a violation of Bell-type inequalities for spatial degrees of freedom.
The spatial correlations among the photons can be understood from state
projection where the detection of the first $m$ photons projects the sources
onto a state which emits the subsequent photon in a strongly correlated manner.
From this perspective the entanglement and violation of Bell's inequalities
appears as a consequence of nonvanishing cross correlations between
noncommuting quadrature phase components of the two spatially separated fields
after $m$ photons have been recorded. In this way we show that classical
systems may produce spatial field correlations violating local realistic
theories.

17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th