中文摘要：

研究了在均匀磁场中的三格点Heisenberg XX自旋环,通过控制一个格点的耦合参数,来调控另外两个格点之间的纠缠.理论上发现当控制格点的耦合参数比未控制格点的耦合参数小时,未控制格点间的纠缠随磁场变化会出现一个纠缠值为1的平台.在较低温度下,平台的宽度与未控制格点间的耦合参数值相等,是一个很好的纠缠开关.同时,分析了存在两个控制格点的情况,也可以得到纠缠值为1的开关,并发现自旋相互作用具有线性关系.

英文摘要：

This paper is devoted to analyse the three-qubit Heisenberg XX rings in a uniform magnetic field, and by controlling of the coupling of a site we can change the entanglement between other two sites. We find that thermal entanglement exhibits a platform-like behaviour and entangled value is equal to 1 when coupling of the site which was controlled is small than that was not controlled,the width of the platform-like region could he controlled by changing the coupling between was not sites, This novel property may be used as a quantum entanglement switch. At the same time, we analyse the situation that two sites were controlled, the entanglement maximal switch still can be realized. Moreover, we find that there are linear relation in the spin-spin interactions.