Pairwise entanglement in finite spin arrays at finite temperature

MATERA, J. M.; CANOSA, N.; ROSSIGNOLI, R. D.

Ciudad Autónoma de Buenos Aire

Congreso; XI Giambiagi Winter School. The Quantum Mechanics of XXI Century: Manipulation of Coherent Atomic Matter; 2009

Departamento de Física J. J. Giambiagi, UBA

We examine the thermal pairwise entanglement in a symmetric system of n spins fully connected through anisotropic XYZ-type couplings embedded in a transverse magnetic field. We consider both the exact evaluation together with that obtained with the static path+random phase approximation RPA and the ensuing mean field+RPA. The latter is shown to provide an accurate analytic description of the thermal concurrence in large systems. We also analyze the limit temperature for pairwise entanglement, which is shown to increase for large fields.Special finite-size effects are also discussed.