Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Coherence expansion and polariton condensate formation in a
  semiconductor microcavity   The dynamics of the expansion of the first order spatial coherence g(1) for a
polariton system in a high-Q GaAs microcavity was investigated on the basis of
Young's double slit experiment under 3 ps pulse excitation at the conditions of
polariton Bose-Einstein condensation. It was found that in the process of
condensate formation the coherence expands with a constant velocity of about
10^8 cm/s. The measured coherence is smaller than that in thermally equilibrium
system during the growth of condensate density and well exceeds it at the end
of condensate decay. The onset of spatial coherence is governed by polariton
relaxation while condensate amplitude and phase fluctuations are not
suppressed.

28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
3
The categories of this paper are: physics
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys