Entanglement Entropy Signature of Quantum Phase Transitions in a Multiple Spin Interactions Model

• Published in: Communications in theoretical physics Vol. 55; no. 2; pp. 349 - 358
• Main Author: 黄海林
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.02.2011
• Subjects: Collapse; Entanglement; Entropy; Excitation; Ground state; Magnetization; Phase transformations; Signatures; 格林函数理论; 相互作用模型; 自旋模型; 自旋相互作用
• ISSN: 0253-6102
• DOI: 10.1088/0253-6102/55/2/27

Through the Jordan Wigner transformation, the entanglement entropy and ground state phase diagrams of exactly solvable spin model with alternating and multiple spin exchange interactions are investigated by means of Green＇s function theory. In the absence of four-spin interactions, the ground state presents plentiful quantum phases due to the multiple spin interactions and magnetic fields. It is shown that the two-site entanglement entropy is a good indicator of quantum phase transition （QPT）. In addition, the alternating interactions can destroy the magnetization plateau and wash out the spin-gap of low-lying excitations. However, in the presence of four-spin interactions, apart from the second order QPTs, the system manifests the first order OPT at the tricritical point and an additional new phase called ＂spin waves＂, which is due to the collapse of the continuous tower-like low-lying excitations modulated by the four-spin interactions for large three-spin couplings.