Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Generation of entangled 3D localized quantum wave-packets via optical
  parametric amplification   In the framework of the paraxial and of the slowly varying envelope
approximations, with reference to a normally dispersive medium or to vacuum,
the electromagnetic field is given as a continuous quantum superposition of
non-dispersive and non-diffracting wave-packets (namely X-waves). Entangled
states as pairs of elementary excitations traveling at (approximately) the same
velocity are found in optical parametric amplification.

26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
10
The categories of this paper are: q-bio