具有三自旋相互作用XX模型纠缠特性研究

Entanglement properties of XX model with three spin interactions

利用Concurrence判据,研究了具有三自旋相互作用的XX模型的纠缠特性;分别在铁磁和反铁磁模型中研究了三自旋相互作用J_2和温度T对两自旋纠缠度的影响.结果表明,三自旋相互作用J_2提高系统的两体纠缠度,但是提高程度会因最近邻自旋间发生铁磁、反铁磁相互作用而有所差异;并且J_2影响两自旋系统纠缠消失的临界温度T_C,T_C会随J_2的增大而减小.系统温度T影响两体纠缠度,随着温度的降低,纠缠度会得到提高.此外,分别在系统本征态和基态中研究了两自旋的纠缠度,求出了系统发生量子相变的量子临界点.

Using the Concurrence criterion, we investigate the entanglement properties of XX model with three spin interactions. The effects of the three spin interaction J2 and temperature T on the entanglement are discussed in both ferromagnetic and anti-ferromagnetic cases. Our results show that J2 en hances the entanglement of the system, but the extent is difference for ferromagnetic and anti-ferromagnetic cases. J2 also affects the critical temperature Tc, at which the entanglement disappears. Tc decreases with the increasing of J2. Moreover, our results also indicate that the maximal entanglement increases with the decreasing of system temperature T. In addition, we also investigate the pairwise entanglement of the eigenstates of the Hamiltonian and discuss the ground-state entanglement. We obtain the quantum critical point at which the quantum phase transition takes place.