Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Propagation of spatially entangled qudits through free space   We show the propagation of entangled states of high-dimensional quantum
systems. The qudits states were generated using the transverse correlation of
the twin photons produced by spontaneous parametric down-conversion. Their
free-space distribution was performed at the laboratory scale and the
propagated states maintained a high-fidelity with their original form. The use
of entangled qudits allow an increase in the quantity of information that can
be transmitted and may also guarantee more privacy for communicating parties.
Therefore, studies about propagating entangled states of qudits are important
for the effort of building quantum communication networks.

25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn