Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Advances in high-order harmonic generation sources for time-resolved
  investigations   We review the main research directions ongoing in the development of
high-harmonic generation-based extreme ultraviolet sources for the
synthesization and application of trains and isolated attosecond pulses to
time-resolved spectroscopy. A few experimental and theoretical works will be
discussed in connection to well-established attosecond techniques. In this
context, we present the unique possibilities offered for time-resolved
investigations on the attosecond timescale by the new Extreme Light
Infrastructure Attosecond Light Pulse Source, which is currently under
construction.

31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
19
The categories of this paper are: eess