Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Reduced density matrix and entanglement entropy of permutationally
  invariant quantum many-body systems   In this paper we discuss the properties of the reduced density matrix of
quantum many body systems with permutational symmetry and present basic
quantification of the entanglement in terms of the von Neumann (VNE), Renyi and
Tsallis entropies. In particular, we show, on the specific example of the spin
$1/2$ Heisenberg model, how the RDM acquires a block diagonal form with respect
to the quantum number $k$ fixing the polarization in the subsystem conservation
of $S_{z}$ and with respect to the irreducible representations of the
$\mathbf{S_{n}}$ group. Analytical expression for the RDM elements and for the
RDM spectrum are derived for states of arbitrary permutational symmetry and for
arbitrary polarizations. The temperature dependence and scaling of the VNE
across a finite temperature phase transition is discussed and the RDM moments
and the R\'{e}nyi and Tsallis entropies calculated both for symmetric ground
states of the Heisenberg chain and for maximally mixed states.

37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex