Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Topologically protected defect states in open photonic systems with
  non-hermitian charge-conjugation and parity-time symmetry   We show that topologically protected defect states can exist in open (leaky
or lossy) systems even when these systems are topologically trivial in the
closed limit. The states appear from within the continuum, thus in absence of a
band gap, and are generated via exceptional points (a spectral transition that
occurs in open wave and quantum systems with a generalized time-reversal
symmetry), or via a degeneracy induced by charge-conjugation-symmetry (which is
related to the pole transition of Majorana zero modes). We demonstrate these
findings for a leaking passive coupled-resonator optical waveguide with
asymmmetric internal scattering, where the required symmetries (non-hermitian
versions of time-reversal symmetry, chirality and charge-conjugation) emerge
dynamically.

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The categories of this paper are: ao-sci
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The categories of this paper are: cs
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
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The categories of this paper are: acc-phys