Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Interaction effects and quantum phase transitions in topological
  insulators   We study strong correlation effects in topological insulators via the Lanczos
algorithm, which we utilize to calculate the exact many-particle ground-state
wave function and its topological properties. We analyze the simple,
noninteracting Haldane model on a honeycomb lattice with known topological
properties and demonstrate that these properties are already evident in small
clusters. Next, we consider interacting fermions by introducing repulsive
nearest-neighbor interactions. A first-order quantum phase transition was
discovered at finite interaction strength between the topological band
insulator and a topologically trivial Mott insulating phase by use of the
fidelity metric and the charge-density-wave structure factor. We construct the
phase diagram at $T = 0$ as a function of the interaction strength and the
complex phase for the next-nearest-neighbor hoppings. Finally, we consider the
Haldane model with interacting hard-core bosons, where no evidence for a
topological phase is observed. An important general conclusion of our work is
that despite the intrinsic nonlocality of topological phases their key
topological properties manifest themselves already in small systems and
therefore can be studied numerically via exact diagonalization and observed
experimentally, e.g., with trapped ions and cold atoms in optical lattices.

12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph