Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measuring High-Order Phonon Correlations in an Optomechanical Resonator   We use single photon detectors to probe the motional state of a superfluid
$^4$He resonator of mass $\sim1$ ng. The arrival times of Stokes and
anti-Stokes photons (scattered by the resonator's acoustic mode) are used to
measure the resonator's phonon coherences up to the fourth order. By
post-selecting on photon detection events, we also measure coherences in the
resonator when $\leq3$ phonons have been added or subtracted. These
measurements are found to be consistent with predictions that assume the
acoustic mode to be in thermal equilibrium with a bath through a Markovian
coupling.

19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con