Thermal entanglement in a two-qubit Heisenberg<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>X</mml:mi><mml:mi>X</mml:mi><mml:mi>Z</mml:mi></mml:mrow></mml:math>spin chain under an inhomogeneous magnetic field 论文

摘要

The thermal entanglement in a two-qubit Heisenberg $XXZ$ spin chain is investigated under an inhomogeneous magnetic field $b$. We show that the ground-state entanglement is independent of the interaction of $z$-component ${J}_{z}$. The thermal entanglement at the fixed temperature can be enhanced when ${J}_{z}$ increases. We strictly show that for any temperature $T$ and ${J}_{z}$, the entanglement is symmetric with respect to zero inhomogeneous magnetic field, and the critical inhomogeneous magnetic field ${b}_{c}$ is independent of ${J}_{z}$. The critical magnetic field ${B}_{c}$ increases with the increasing $\ensuremath{\mid}b\ensuremath{\mid}$ but the maximum entanglement value that the system can arrive at becomes smaller.