Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An acoustic black hole in a stationary hydrodynamic flow of microcavity
  polaritons   We report an experimental study of superfluid hydrodynamic effects in a
one-dimensional polariton fluid flowing along a laterally patterned
semiconductor microcavity and hitting a micron-sized engineered defect. At high
excitation power, superfluid propagation effects are observed in the polariton
dynamics, in particular, a sharp acoustic horizon is formed at the defect
position, separating regions of sub- and super-sonic flow. Our experimental
findings are quantitatively reproduced by theoretical calculations based on a
generalized Gross-Pitaevskii equation. Promising perspectives to observe
Hawking radiation via photon correlation measurements are illustrated.

37
The categories of this paper are: supr-con
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics