Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Symmetry between absorption and amplification in disordered media   We address the issue of whether amplification, like absorption, suppresses
wave transmission at large gain, as has been claimed in previous studies of
wave propagation in active random media. A closer examination reveals that the
paradoxical symmetry between absorption and amplification is an artifact of
unphysical solutions from the time-independent wave equation. Solutions from
the time-dependent equation demonstrate clearly that when gain is above the
threshold, the amplitude of both the transmitted and the reflected wave
actually increases with time, apparently without bound. The implications of the
current finding is discussed

17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
6
The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an