Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exceptional points of PT-symmetric reflectionless states in complex
  scattering systems   We investigate experimentally and analytically the coalescence of
reflectionless (RL) states in symmetric complex wave-scattering systems. We
observe RL-exceptional points (EPs), first, with a conventional Fabry-Perot
system for which the scattering strength within the system is tuned
symmetrically, and then with single- and multi-channel symmetric disordered
systems. We identify that an EP of the parity-time (PT)-symmetric RL-operator
is obtained when the spacing between central frequencies of two natural
resonances of the system is equal to the decay rate into incoming and outgoing
channels. Finally, we leverage the transfer functions associated with RL and
RL-EPs states to implement first- and second-order analog differentiation.

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The categories of this paper are: dg-ga
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
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The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
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The categories of this paper are: q-alg
25
The categories of this paper are: patt-sol
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The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
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The categories of this paper are: q-fin