Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultrafast optical spectroscopy of strongly correlated materials and
  high-temperature superconductors: a non-equilibrium approach   In the last two decades, non-equilibrium spectroscopies have evolved from
avant-garde studies to crucial tools for expanding our understanding of the
physics of strongly correlated materials. The possibility of obtaining
simultaneously spectroscopic and temporal information has led to insights that
are complementary to (and in several cases beyond) those attainable by studying
the matter at equilibrium. Multiple phase transitions and new orders arising
from competing interactions are benchmark examples where the interplay among
electrons, lattice, and spin dynamics can be disentangled because of the
different timescales that characterize the recovery of the initial ground
state. The nature of the broken-symmetry phases and of the bosonic excitations
that mediate the electronic interactions, eventually leading to
superconductivity or other exotic states, can be revealed by observing the
sub-picosecond dynamics of impulsively excited states. Recent experimental
developments have made possible to monitor the time-evolution of both the
single-particle and collective excitations under extreme conditions, such as
those arising from strong and selective photo-stimulation.
  Here, we review the most recent achievements in the experimental and
theoretical studies of the non-equilibrium electronic, optical, structural and
magnetic properties of correlated materials. The focus will be mainly on the
prototypical case of correlated oxides that exhibit unconventional
superconductivity or other exotic phases, even though the discussion will
extend also to other topical systems. The necessity of extending the actual
experimental capabilities and the numerical and analytic tools to
microscopically treat the non-equilibrium phenomena beyond the simple
phenomenological approaches represents one of the most challenging new frontier
in physics.

30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an