Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Efficient single-spatial-mode periodically-poled KTiOPO_4 waveguide
  source for high-dimensional entanglement-based quantum key distribution   We demonstrate generation of high-purity photon pairs at 1560 nm in a single
spatial mode from a periodically-poled KTiOPO_4 (PPKTP) waveguide. With nearly
lossless spectral filtering, the PPKTP waveguide source shows approximately 80
% single-mode fiber coupling efficiency and is well suited for high-dimensional
time-energy entanglement-based quantum key distribution. Using high-count-rate
self-differencing InGaAs single-photon avalanche photodiodes configured with
either square or sinusoidal gating, we achieve > 1 Mbit/s raw key generation
with 3 bits-per-photon encoding, and, to the best of our knowledge, the highest
reported Franson quantum-interference visibility of 98.2 % without subtraction
of accidental coincidences.

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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: math
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The categories of this paper are: q-bio
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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-th
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The categories of this paper are: atom-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: acc-phys
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The categories of this paper are: q-fin