拓扑量子相变的动力学性质研究

项目名称： 拓扑量子相变的动力学性质研究

项目编号： No.10874215

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 向涛

作者单位： 中国科学院物理研究所

项目金额： 40万元

中文摘要： 本项目按照研究计划，围绕拓扑量子相变的动力学性质这个主题，对拓扑量子系统的相变及机理、拓扑量子序的刻画问题做了系统分析。 提出了在对称性部分破缺的量子系统由熵驱动的相变理论，丰富了相变理论的内涵。研究了朗道相变理论禁戒的拓扑量子相变问题。这种相变系统有分数化的临界量子激发和解禁闭的量子相变，是近年来研究的一个热点方向。我们找到了两个可能存在这种新的相变现象的自旋模型，为这方面的研究提供了一个好的起点。提出用最大非定域弦序参量来表征拓扑量子序的理论，对深入研究拓扑对称性的破缺机理有参考价值。

中文关键词： 拓扑量子相变；拓扑激发；非阿贝尔统计；量子计算

英文摘要： We have investigated systematically physical problems related to the dynamical properties of topological quantum phase transtion, in particular the microscopic mechanism of topological phase transition and the characterization of topological quantum orders. We have proposed a novel theory of phase transition driven by the entropy for the system which has partial symmetry breaking. This work enriches the Landau continuous phase transition theory. We have studied a special kind continuous quantum phase transition which is forbidden by the Landau phase transition theory. This kind of system is physically interesting since it contains a deconfined quantum phase and its critical excitations are fractionalized. Based on solid numerical calculation, we found two quantum spin models, defined in one and two dimensional lattice systems, respectively, which may be taken as two candidates for further studying the Landau-forbidden phase transition. We have showed that the topological quantum order can be characterized by the maximal non-local string order parameter, which can be used to further explore the mechanism oftopological symmetry breaking.

英文关键词： topological phase transition; topological excitation; non-Abelian statistics; quantum computation