Enhanced thermal entanglement in an anisotropic Heisenberg XYZ chain

The thermal entanglement in the Heisenberg XYZ chain is investigated in the presence of an external magnetic field B. In the two-qubit system, the critical magnetic field Bc is increased by introducing the interaction of the z component of two neighboring spins Jz. This interaction not only improves the critical temperature Tc, but also enhances the entanglement for a particular fixed B. We also analyze the pairwise entanglement between nearest neighbors in three qubits. The pairwise entanglement, for a fixed T, can become strong by controlling B and Jz