Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-Ray Entangled Photon Production in Collisions of Laser Beams with
  Relativistic Ions   A method is suggested to produce, with the help of colliding laser photons
with bunches of relativistic ions having two energy levels, both intense beams
of monochromatic polarized X-ray fluorescence photons and significant number of
X-ray entangled photons, via double Doppler transformation. Nonlinear
susceptibility of the ions, the cross section and the rate of production of
such photons at RHIC are estimated. Such beams of X-ray photons can be detected
and applied to solve various problems, in a manner similar to the usage of
optical photons.

9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
23
The categories of this paper are: solv-int