Entanglement of finite spin chains at factorizing fields

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

Departamento de Física, FCE, UBA

Workshop; THE QUANTUM MECHANICS OF THE XXI CENTURY: MANIPULATION OF COHERENT ATOMIC MATTER : Eleventh J. J. Giambiagi Winter School.; 2009

Departamento de Física, FCE, UBA, CONICET

We examine the entanglement of finite chains with anisotropic $XYZ$ couplings of arbitrary range at transverse factorizing  fields. At these fields the system exhibits a degenerate parity breaking ground state  which is exactly separable. It is shown, however, that in finite chains the side limits of the ground state pairwise entanglement at these fields are actually  non-zero, corresponding such fields to a ground state parity transition. These limits are  independent of both the pair separation and interaction range, and can be  directly related to the magnetization step. Illustrative exact results for nearest neighbor as well as full rangecouplings  will be shown. Other general properties at such points will also be discussed.