论文标题
四方旋转1/2平方簇中的稳健量子纠缠和传送：关于循环四旋转效果的理论研究
Robust quantum entanglement and teleportation in the tetrapartite spin-1/2 square clusters: Theoretical study on the effect of a cyclic four-spin exchange
论文作者
论文摘要
在四核方形群集上，与循环四翼互动的四核方形群集在四核方形群集上，纠缠$π_4$的缠结平均值和抗磁性自旋1/2 XXX Heisenberg模型的平均值得到了严格的检查。该型号包括两个最近的氯交换耦合$ j_1 $和$ j_2 $，因此$ j_1 \ gg j_2 $。当环状四旋转交换为零时，整个纠缠$π_4$的最大值将在低温和相对较高的磁场$（b \ of j_1）$下实现。同样，在高温和高磁场上，双旋转与交换耦合$ j_1 $之间的最大两分纠缠是可以实现的。该数量仍然活着，以足够的高温和高磁场值与相关的交换耦合$ j_1 $相当。环状四旋转交换的非零值显着增强了整个纠缠的程度，而它削弱了两部分纠缠程度。我们证明，整个纠缠达到了一个非常规的最小值，在循环四旋转交换的特殊参数区域几乎小于$ j_1 $的十个数量级，该系统处于量子抗铁磁状态。 The real complex $[\text{Cu}_4\text{L}_4(\text{H}_2\text{O})_4](\text{ClO}_4)_4$ as a strong antiferromagnetic tetranuclear square compound provides us an experimental representative to estimate the strength of the whole and bipartite entanglements at high enough temperature.已经证明，该复合物的纠缠否定性尚未取决于所考虑的环状四旋转相互作用，即使其大小明显小于$ j_1 $。
The whole entanglement measure so-called geometric $Π_4$ average of tangles and bipartite entanglement of the antiferromagnetic spin-1/2 XXX Heisenberg model on a tetranuclear square cluster with cyclic four-spin interaction are rigorously examined by the help of thermal negativities. The model comprises two nearest-neighbor exchange couplings $J_1$ and $J_2$ such that $J_1\gg J_2$. When the cyclic four-spin exchange is zero, the maximum value of whole entanglement $Π_4$ is achieved at low enough temperatures and relatively high magnetic fields $(B\approx J_1)$. Also, maximum bipartite entanglement between pair spins with exchange coupling $J_1$ is achievable at high temperature and high magnetic field. This quantity remains alive for sufficiently high temperature and high magnetic field values comparable with the relevant exchange coupling $J_1$. A nonzero value of the cyclic four-spin exchange notably enhances the degree of the whole entanglement, while it weakens the bipartite entanglement degree. We demonstrate that the whole entanglement reaches an unconventional minimum at a special parameter region of cyclic four-spin exchange almost ten order of magnitude smaller than $J_1$, where the system is in a quantum antiferromagnetic state. The real complex $[\text{Cu}_4\text{L}_4(\text{H}_2\text{O})_4](\text{ClO}_4)_4$ as a strong antiferromagnetic tetranuclear square compound provides us an experimental representative to estimate the strength of the whole and bipartite entanglements at high enough temperature. It is demonstrated that the entanglement negativities of this complex are yet depend on the considered cyclic four-spin interaction even though its magnitude is significantly smaller than $J_1$.
