Three-qubit Thermal Entanglement via Entanglement Swapping on Two-qubit Heisenberg XY chains

摘要

In this paper we consider the generation of a three-qubit GHZ-like thermalstate by applying the entanglement swapping scheme of Zukowski {\it et al.}[Ann. N. Y. Acad. Sci. {\bf 755}, 91 (1995)] to three pairs of two-qubitHeisenberg XY chains. The quality of the resulting three-qubit entanglement isstudied by analyzing the teleportation fidelity, when it is used as a resourcein the teleportation protocol of Karlsson {\it et al.}[Phys. Rev. A {\bf 58},4394 (1998)]. We show that even though thermal noise in the original two-qubitstates is amplified by the entanglement swapping process, we are still able toachieve nonclassical fidelities for the anisotropic Heisenberg XY chains atfinitely higher and higher temperatures by adjusting the strengths of anexternal magnetic field. This has a positive implication on the solid-staterealization of a quantum computer.