Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of topological valley transport of sound in sonic crystals   Valley pseudospin, labeling quantum states of energy extrema in momentum
space, is attracting tremendous attention1-13 because of its potential in
constructing new carrier of information. Compared with the non-topological bulk
valley transport realized soon after predictions1-5, the topological valley
transport in domain walls6-13 is extremely challenging owing to the
inter-valley scattering inevitably induced by atomic scale imperfectness, until
the recent electronic signature observed in bilayer graphene12,13. Here we
report the first experimental observation of topological valley transport of
sound in sonic crystals. The macroscopic nature of sonic crystals permits the
flexible and accurate design of domain walls. In addition to a direct
visualization of the valley-selective edge modes through spatial scanning of
sound field, reflection immunity is observed in sharply curved interfaces. The
topologically protected interface transport of sound, strikingly different from
that in traditional sound waveguides14,15, may serve as the basis of designing
devices with unconventional functions.

14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph