Global entanglement in XXZ chains

N. CANOSA; R. ROSSIGNOLI

PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS

American Physical Society

Lugar: N.Y.; Año: 2006 vol. 73 p. 223471 - 223478

1050-2947

We examine the thermal entanglement of XXZ-type Heisenberg chains in thepresence of a uniform magnetic field along the z axes, through the evaluation of the negativity associated with bipartitions of the whole system andsubsystems. Limit temperatures for non-zero global negativities are shown todepend on the asymmetry Delta but not on the uniform field, and can be muchhigher than those limiting pairwise entanglement. It is also shown that globalbipartite entanglement may exist for T>0 even for Deltageq 1, i.e., whenthe system is fully aligned (and hence separable) at T=0, and that thebipartition leading to the highest limit temperature depends on Delta.