Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dual bound states in the continuum in metamaterials   Bound state in the continuum (BIC) is a mathematical concept with an infinite
radiative quality factor (Q) that exists only in an ideal infinite array. It
was first proposed in quantum mechanics, and extended to general wave phenomena
such as acoustic, water, elastic, and electromagnetic waves. In photonics, it
is essential to achieve high Q resonances for enhanced light-mater interactions
that could enable low-threshold lasers, ultrasensitive sensors, and optical
tweezers. Here, we demonstrate dual bound states in the continuum in a
subwavelength planar metamaterial cavity that reveal symmetry-protected
features excited by orthogonal polarizations. The spectral features of dual
BICs are experimentally verified in the terahertz domain by breaking the C2
symmetry that invokes a leakage channel. The radiative Q factors tend to
infinity at a discrete symmetry-restoring point and obey an inverse square
dependence on the structural asymmetry. Metamaterials allow field confinement
in extremely small mode volumes, thereby improving the rate of spontaneous
emission in the cavity with a much larger Purcell factor along with high Q
factor. The symmetry-protected BICs in metamaterials also possess the unique
advantage of scalability at different wavelengths for potential applications in
sensing, lasing, switching, and spectral filtering.

25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
6
The categories of this paper are: astro-ph
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn