Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superradiance of molecular nitrogen ions in strong laser fields   We perform a combined theoretical and experimental investigation of the
superradiance in the quantum coherent system generated by strong laser fields.
The semiclassical theory of superradiance that includes the superradiant
temporal profile, character duration, time delay, intensity is derived. The
experimental data and theoretical predictions of 391-nm forward emission as a
function of nitrogen gas pressure are compared and show good agreement. Our
results not only demonstrate that the time-delayed optical amplification inside
the molecular nitrogen ions is superradiance, but also reveal the quantum
optical properties of strong-field physics.

10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th