Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Correlated electron-hole State in Twisted Double Bilayer Graphene   When twisted to angles near 1{\deg}, graphene multilayers provide a new
window on electron correlation physics by hosting gate-tuneable
strongly-correlated states, including insulators, superconductors, and unusual
magnets. Here we report the discovery of a new member of the family,
density-wave states, in double bilayer graphene twisted to 2.37{\deg}. At this
angle the moir\'e states retain much of their isolated bilayer character,
allowing their bilayer projections to be separately controlled by gates. We use
this property to generate an energetic overlap between narrow isolated electron
and hole bands with good nesting properties. Our measurements reveal the
formation of ordered states with reconstructed Fermi surfaces, consistent with
density-wave states, for equal electron and hole densities. These states can be
tuned without introducing chemical dopants, thus opening the door to a new
class of fundamental studies of density-waves and their interplay with
superconductivity and other types of order, a central issue in quantum matter
physics.

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The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
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The categories of this paper are: econ
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom