Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Acoustic square-root topological insulators   Square-root topological states are new topological phases, whose topological
property is inherited from the square of the Hamiltonian. We realize the
first-order and second-order square-root topological insulators in phononic
crystals, by putting additional cavities on connecting tubes in the acoustic
Su-Schrieffer-Heeger model and the honeycomb lattice, respectively. Because of
the square-root procedure, the bulk gap of the squared Hamiltonian is doubled.
In both two bulk gaps, the square-root topological insulators possess multiple
localized modes, i.e., the end and corner states, which are evidently confirmed
by our calculations and experimental observations. We further propose a
second-order square-root topological semimetal by stacking the decorated
honeycomb lattice to three dimensions.

17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math