Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of Magic Angle and Wall State in Twisted Bilayer Photonic
  Graphene   Graphene, a one-layer honeycomb lattice of carbon atoms, exhibits
unconventional phenomena and attracts much interest since its discovery.
Recently, an unexpected Mott-like insulator state induced by moir\'e pattern
and a superconducting state are observed in magic-angle-twisted bilayer
graphene, especially, without correlations between electrons, which gives more
hints for the understanding and investigation of strongly correlated phenomena.
The photon as boson, behaving differently with fermion, can also retrieve the
unconventional phenomena of graphene, such as the bearded edge state which is
even never been observed in graphene due to the unstability. Here, we present a
direct observation of magic angle and wall state in twisted bilayer photonic
graphene. We successfully observe the strong localization and rapid diffusion
of photon at the regions with AA and AB stacking order around the magic angle,
respectively. Most importantly, we find a wall state showing the photon
distribution distinctly separate at the regions with AA and AB/BA stacking
order in the lowest-energy band. The mechanism underlying the wall states may
help to understand the existence of both Mott-like insulating state and
superconducting state in magic-angle twisted bilayer graphene. The
accessibility of magic angle in twisted bilayer photonic graphene adds the
boson behavior into graphene superlattice and the observation of wall state
will also deep the understanding of matter.

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The categories of this paper are: stat
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-lat
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The categories of this paper are: supr-con
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The categories of this paper are: atom-ph
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The categories of this paper are: q-alg
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The categories of this paper are: astro-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
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The categories of this paper are: q-bio
1
The categories of this paper are: cs