Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On-demand coherent perfect absorption in complex scattering systems:
  time delay divergence and enhanced sensitivity to perturbations   Non-Hermitian photonic systems capable of perfectly absorbing incident
radiation recently attracted much attention both because fundamentally they
correspond to an exotic scattering phenomenon (a real-valued scattering matrix
zero) and because their extreme sensitivity holds great technological promise.
The sharp reflection dip is a hallmark feature underlying many envisioned
applications in precision sensing, secure communication and wave filtering.
However, a rigorous link between the underlying scattering anomaly and the
sensitivity of the system to a perturbation is still missing. Here, we develop
a theoretical description in complex scattering systems which quantitatively
explains the shape of the reflection dip. We further demonstrate that coherent
perfect absorption (CPA) is associated with a phase singularity and we relate
the sign of the diverging time delay to the mismatch between excitation rate
and intrinsic decay rate. We confirm our theoretical predictions in experiments
based on a three-dimensional chaotic cavity excited by eight channels. Rather
than relying on operation frequency and attenuation inside the system to be two
free parameters, we achieve "on-demand" CPA at an arbitrary frequency by
tweaking the chaotic cavity's scattering properties with programmable meta-atom
inclusions. Finally, we theoretically prove and experimentally verify the
optimal sensitivity of the CPA condition to minute perturbations of the system.

34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th