Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Twisted Radio Waves and Twisted Thermodynamics   We present and analyze a gedanken experiment and show that the assumption
that an antenna operating at a single frequency can transmit more than two
independent information channels to the far field violates the Second Law of
Thermodynamics. Transmission of a large number of channels, each associated
with an angular momentum "twisted wave" mode, to the far field in free space is
therefore not possible.

35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
19
The categories of this paper are: eess
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
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The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th