Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Entanglement in the Quantum Heisenberg XY model   We study the entanglement in the quantum Heisenberg XY model in which the
so-called W entangled states can be generated for 3 or 4 qubits. By the concept
of concurrence, we study the entanglement in the time evolution of the XY
model. We investigate the thermal entanglement in the two-qubit isotropic XY
model with a magnetic field and in the anisotropic XY model, and find that the
thermal entanglement exists for both ferromagnetic and antiferromagnetic cases.
Some evidences of the quantum phase transition also appear in these simple
models.

18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int