Entanglement of the Thermal State of an Anisotropic XYZ Spin Chain in an Inhomogeneous Constant Magnetic Field

A system of a two-qubit Heisenberg anisotropic XYZ spin chain in an inhomogeneous constant magnetic field with the Dzyaloshinskii–Moriya interaction is studied. The energy eigenvalues, the corresponding eigenstates and the thermal states of the system are evaluated. The entanglement is investigated according to Wootter's concurrence. The concurrence is studied against temperature for different values of the parameters involved.