约化忠实度和冯·诺依曼熵分析J₁-J₂海森堡自旋链的相变问题

约化忠实度和冯·诺依曼熵分析J 1 -J 2 海森堡自旋链的相变问题 Reduced Fidelity and von Neumann Entropy Approach to Quantum Phase Transition for the J 1 -J 2 Heisenberg Spin Chain 谢义亮 XIE Yiliang 1 first-author 揭泉林 JIE Quanlin 1 武汉大学物理科学与技术学院 武汉大学物理科学与技术学院 School of Physics and Technology,Wuhan University School of Physics and Technology,Wuhan University 采用精确对角化方法,研究自旋1/2一维J1-J2海森堡自旋链模型的相变问题.通过计算激发态下自旋格点群的约化忠实度和冯·诺依曼熵,确定了该系统由自旋液体态到二聚态之间的K-T相变,并通过外推法,确定相变点位置L→∞,λc=0.241 14.研究结果表明,难以用传统序参量来刻画的K-T相变可以用自旋格点群（子系统）的约化忠实度和冯·诺依曼熵来反映. In this paper,exact diagonalization（ED）method is used to investigate the quantum phase transition in one-dimension spin 1/2 J1-J2 Heisenberg model.Through the calculation of reduced fidelity and von Neumann entropy of spin cluster in the excited states of the model,the phase transition point of Kosterlitz-Thouless transition（K-T）is determined between spin fluid and dimerized phase in the system,and its theoretical value L→∞,λc=0.241 14 in the phase transition point are drawn by extrapolation.The results suggest that,K-T phase transition,elusive to be characterized through traditional order parameter,is accessible by using these two calculation methods of reduced fidelity and von Neumann entropy of spin cluster（subsystem）. 量子相变 海森堡自旋链 约化忠实度 冯·诺依曼熵 quantum phase transition Heisenberg spin chain reduced fidelity von Neumann entropy 10.14188/j.1671-8836.2014.03.001 O469 国家自然科学基金资助项目（10875087） 2014-03-01 2021-04-01 3 60