Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultrafast Quantum-path Interferometry Revealing the Generation Process
  of Coherent Phonons   Optical dual-pulse pumping actively creates quantum-mechanical superposition
of the electronic and phononic states in a bulk solid. We here made transient
reflectivity measurements in an n-GaAs using a pair of relative-phase-locked
femtosecond pulses and found characteristic interference fringes. This is a
result of quantum-path interference peculiar to the dual-pulse excitation as
indicated by theoretical calculation. Our observation reveals that the pathway
of coherent phonon generation in the n-GaAs is impulsive stimulated Raman
scattering at the displaced potential due to the surface-charge field, even
though the photon energy lies in the opaque region.

10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat