Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High Fidelity Detection of the Orbital Angular Momentum of Light by Time
  Mapping   We demonstrate high-fidelity detection of the orbital angular momentum (OAM)
of light using a compact and practical OAM spectrometer that maps the OAM
spectrum to time. The spectrometer consists of a single optical delay loop to
achieve timing mapping, a vortex phase plate that iteratively decreases the OAM
value, and a single mode fibre to distinguish zero from non-zero OAM states.
Light with arbitrarily OAM compositions can be measured. For light with OAM up
to 4hbar, we measured an average crosstalk of -21.3 dB, which is mainly limited
by the purity of the input states and optical alignment.

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The categories of this paper are: gr-qc
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga
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The categories of this paper are: cs
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The categories of this paper are: math
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The categories of this paper are: alg-geom
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas