Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Transformation of subradiant state to superradiant state in a thick
  resonant medium   The propagation of a step pulse through a thick resonant absorber with
homogeneously broadened absorption line is considered. It is shown that a
specific subradiant state is naturally developed in the absorber due to the
formation of the spatial domains of the atomic coherence with opposite phases.
It is proposed to divide the absorber into slices in accord with these domains
and place the phase shifters in front of the first slice and between the other
slices. If the phase shifters are switched on simultaneously at a particular
moment of time, elapsed from the beginning of the step pulse, a strong sharp
pulse is generated at the output of the last slice of the absorber. The effect
is explained by the phasing of the atomic coherence along all slices of the
absorber, which transforms subradiant state of atom-field system to
superradiant state.

28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an