Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Geometry and superfluidity of the flat band in a non-Hermitian optical
  lattice   We propose an ultracold-atom setting where a fermionic superfluidity with
attractive s-wave interaction is uploaded in a non-Hermitian Lieb optical
lattice. The existence of a real-energy flat band solution is revealed. We show
that the interplay between the skin effect and flat-band localization leads to
exotic localization properties. We develop a multiband mean-field description
of this system and use both order parameters and superfluid weight to describe
the phase transition. A relation between the superfluid weight and
non-Hermitian quantum metric of the quantum states manifold is built. We find
non-monotone criticality depending on the non-Hermiticity, and the
non-reciprocity prominently enhances the phase coherence of the pairing field,
suggesting ubiquitous critical behavior of the non-Hermitian fermionic
superfluidity.

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The categories of this paper are: physics
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
19
The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: plasm-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: alg-geom