Entanglement and teleportation through thermal equilibrium state of spins in the XXZ model

We study the pairwise entanglement of a three-qubit spins in the XXZ model, and teleport an unknown state using the spin chain in the thermal equilibrium as a quantum channel. The effects of coupling strength, magnetic field, the anisotropy and temperature oil the entanglement and fidelity are investigated. We find that the ferromagnetic spin chain is suitable for quantum teleportation, while the antiferromagnetic one is not. We give the maximal average fidelity, and the condition under which the maximal average fidelity is obtained. In addition, the relation between the entanglement and fidelity is studied,, and we find that the considered entanglement cannot completely reflect the fidelity. (c) 2005 Elsevier B.V. All rights reserved.