IFLP   13074
INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
artículos
Título:
Evaluation of pairwise entanglement in translationally invariant systems with the random phase approximation
Autor/es:
MATERA, J. M.; ROSSIGNOLI, R. D.; CANOSA, N.
Revista:
PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS
Referencias:
Año: 2008 vol. 78 p. 42319 - 42319
ISSN:
1050-2947
Resumen:
We discuss a general mean field plus random phase approximation (RPA)
for describing composite systems at zero and finite temperature. We
analyze in particular its implementation in finite systems invariant
under translations, where for uniform mean fields it requires just the
solution of simple local-type RPA equations. As test and application,
we use the method for evaluating the entanglement between two spins in
cyclic spin1/2 chains with both long- and short-range anisotropic XY-type
couplings in a uniform transverse magnetic field. The approach is shown
to provide an accurate analytic description of the concurrence for
strong fields, for any coupling range, pair separation, or chain size,
where it predicts an entanglement range which can be at most twice that
of the interaction. It also correctly predicts the existence of a
separability field together with full entanglement range in its
vicinity. The general accuracy of the approach improves as the range of
the interaction increases.