Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unveiling pseudospin and angular momentum in photonic graphene   Pseudospin, an additional degree of freedom inherent in graphene, plays a key
role in understanding many fundamental phenomena such as the anomalous quantum
Hall effect, electron chirality and Klein paradox. Unlike the electron spin,
the pseudospin was traditionally considered as an unmeasurable quantity, immune
to Stern-Gerlach-type experiments. Recently, however, it has been suggested
that graphene pseudospin is a real angular momentum that might manifest itself
as an observable quantity, but so far direct tests of such a momentum remained
unfruitful. Here, by selective excitation of two sublattices of an artificial
photonic graphene, we demonstrate pseudospin-mediated vortex generation and
topological charge flipping in otherwise uniform optical beams with Bloch
momentum traversing through the Dirac points. Corroborated by numerical
solutions of the linear massless Dirac-Weyl equation, we show that pseudospin
can turn into orbital angular momentum completely, thus upholding the belief
that pseudospin is not merely for theoretical elegance but rather physically
measurable.

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The categories of this paper are: econ
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
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The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
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The categories of this paper are: math-ph
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: math
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
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The categories of this paper are: dg-ga
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The categories of this paper are: chem-ph
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The categories of this paper are: comp-gas