多量子位Heisenberg XX链中的杂质纠缠

通过分析系统的杂质位与其余部分间的纠缠N_1-A以及单个正常位与其余部分间的纠缠N_L-A研究了匀强磁场作用下含杂质Heisenberg XX链的纠缠特性.研究表明三量子位时纠缠存在的临界温度依赖于杂质参数J₁和匀强磁场B.研究发现，当量子位L为奇数时，纠缠N_1-A随量子位的增加而增大，而L为偶数时则相反，并且量子位L为偶数时的纠缠大于量子位L为奇数时的纠缠；对N_L-A, 量子位L为奇数时，纠缠随杂质参数J₁的变化与L=3类似，而L为偶数时纠缠随杂质参数|J₁|的增加而增加.

Multipartite entanglement in the Heisenberg XX chain with impurity

We studied the entanglements of the Heisenberg XX chain with impurity in the presence of a uniform magnetic field along the z axes by means of negativity. Through analyzing N_L-A and N_1-A, we show that the critical temperatures for nonzero negativities depend on the impurity parameter J₁ and the magnetic field B. It is also shown that as qubit L increases, the entanglements increase when L is odd but decrease when L is even. And the entanglements of the even-qubit chains are larger than those of the odd-qubit chains. The condition is similar with L=3 for N_L-A when qubit L is odd, but the entanglements increase with the increase of even qubit L.