研究了带有次近邻和三体相互作用的S =1自旋链的保真率和纠缠熵.通过密度矩阵重整化群数值方法计算了三体相互作用对保真率的影响,并分析了其与量子相变的关系.研究表明保真率可以探测Haldane相与二聚物相之间的相变.此外还研究了该相变与量子纠缠熵的关系.通过保真率和量子纠缠熵这两个信息观测量得到的结果和弦序参量得到的结果一致.在此基础之上给出了相图.%In the present work, we study the fidelity susceptibility and the entanglement entropy in an antiferromagnetic spin-1 chain with additional next-nearest neighbor interactions and three-site interactions,which are given by H=i (J1Si·Si+1+J2Si·Si+2)+i [J3(Si·Si+1)(Si+1·Si+2)+h.c.]. By using the density matrix renormalization group method,the ground-state properties of the system are calculated with very high accuracy. We investigate the effect of the three-site interaction J3on the fidelity susceptibility numerically, and then analyze its relation with the quantum phase transition (QPT). The fidelity measures the similarity between two states, and the fidelity susceptibility describes the associated changing rate. The QPT is intuitively accompanied by an abrupt change in the structure of the ground-state wave function,so generally a peak of the fidelity susceptibility indicates a QPT and the location of the peak denotes the critical point. For the case of J2= 0, a peak of the fidelity susceptibility is found by varying J3,and the height of the peak grows as the system size increases. The location of the peak shifts to a slightly lower J3up to a particular value as the system size increases. Through a finite size scaling,the critical point Jc3=0.111 of the QPT from the Haldane spin liquid to the dimerized phase is identified. We also study the effect of the three-site interaction on the entanglement entropy between the right half part and the rest. It is noted that the peak of the entanglement entropy does not coincide with the critical point. Instead,the critical point is determined by the position at which the first-order derivative of the entanglement entropy takes its minimum,since a second-order QPT is signaled by the first derivative of density matrix element. Moreover,the entanglement entropy disappears when J3=1/6, which corresponds to the size-independent Majumdar-Ghosh point. The positions of quantum critical points extracted from these two quantum information observables agree well with those obtained by the string order parameters, which characterizes the topological order in the Haldane phase. Secondly, we also study the case of J2=0, and obtain the critical points by both the fidelity susceptibility and the entanglement entropy. Finally we provide a ground-state phase diagram of the system. To sum up, the quantum information observables are effective tools for detecting diverse QPTs in spin-1 models.
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