Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Twisted superfluid phase in the extended one-dimensional Bose-Hubbard
  model   In one-dimensional systems a twisted superfluid phase is found which is
induced by a spontaneous breaking of the time-reversal symmetry. Using the
density-matrix renormalization group allows us to show that the excitation
energy gap closes exponentially causing a quasi-degenerate ground state. The
two degenerate ground states are connected by the time-reversal symmetry which
manifests itself in an alternating complex phase of the long-range correlation
function. The quantum phase transition to the twisted superfluid is driven by
pair tunneling processes in an extended Bose-Hubbard model. The phase
boundaries of several other phases are discussed including a supersolid, a pair
superfluid, and a pair supersolid phase as well as a highly unconventional Mott
insulator with a degenerate ground state and a staggered pair correlation
function.

30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
2
The categories of this paper are: math