Anisotropy and Magnetic Field Effects on the Entanglement of a Two Qubit Heisenberg XY Chain
G. Lagmago Kamta, Anthony F. Starace · Physical Review Letters · 2002
We investigate the entanglement of a two-qubit anisotropic Heisenberg XY chain in thermal equilibrium at temperature T in the presence of an external magnetic field B along the z axis. By means of the combined influences of anisotropic interactions and a magnetic field B, one is able to produce entanglement for any finite T, by adjusting the magnetic field strength. This contrasts with the isotropic interaction or the B = 0 cases, for which there is no entanglement above a critical temperature T(c) that is independent of the external B field.