Dzyaloshinskii-Moriya interaction effects on the entanglement dynamics of a two qubit XXZ spin system in non-Markovian environment

We investigate the entanglement dynamics of a two-qubit Heisenberg XXZ chain with Dzyaloshinskii-Moriya (DM) interactions, interacting with an anisotropic spin bath in thermal equilibrium at temperature T, driven by an external magnetic field B along the z-axis. We establish that, for an initially entangled qubit pair, the DM interactions generate entanglement and enhance it in the revival region. At high temperatures and for weak coupling between the two qubits, the DM interactions preserve entanglement. It is seen that increasing simultaneously the XY component Ω, and the z-component Γz, of the Heinsenberg interaction does not increase the entanglement, but it can rather be improved by increasing their anisotropy χ=|Γz−Ω|. These effects are weakened when the magnetic field B and the Heisenberg coupling are switched on. If the two-qubits are prepared in an initially separable state, the DM interaction instead has a negative effect on their entanglement. As a whole, entanglement can better be preserved in the spin chain even at high temperatures by increasing the external magnetic field B and the Heisenberg couplings, and by tuning the strengths of the Heinsenberg couplings and the DM interaction.