Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Topological properties of two-dimensional photonic square lattice
  without $C_4$ and $M_{x(y)}$ symmetries   Rich topological phenomena, edge states and two types of corner states, are
unveiled in a two-dimensional square-lattice dielectric photonic crystal
without both $C_4$ and $M_{x(y)}$ symmetries. Specifically, non-trivial type-I
corner states, which do not exist in systems with $C_4$ and $M_{x(y)}$ since
the degeneracy, are protected by non-zero quadrupole moment, no longer
quantized to but less than $0.5$. Excellent properties, e.g. sub-wavelength
localization and air-concentrated field distribution, are presented. Type-II
corner states, induced by long-range interactions, are easier realized due to
asymmetry. This work broadens the topological physics for the symmetries-broken
systems and provides potential applications.

29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg