Phase-ordering kinetics and defect dynamics beyond the Landau-Ginzburg description

超出 Landau-Ginzburg 描述的相序动力学和缺陷动力学

基本信息

批准号：
EP/G049394/1
负责人：
Claudio Castelnovo
金额：
$ 31.79万
依托单位：
University of Oxford
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2009
资助国家：
英国
起止时间：
2009 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FG049394%2F1
关键词：
Phase ordering kinetics defect dynamics

项目摘要

Understanding how order emerges across a phase transition, and the behaviour of the corresponding defects, have long been of interest in fields as diverse as condensed matter physics and cosmology. Most of the work to date, however, is concerned with phase transitions that allow for a Landau-Ginzburg (LG) description in terms of a local order parameter. Recent years have witnessed the discovery of a wide range of theoretical models and experimental systems that escape the LG paradigm. For example, in quantum Hall systems, topological order appears as an emergent -- rather than broken -- symmetry at low temperatures, and it cannot be detected by local observables. In frustrated magnets, such as rare earth titanates of Holmium and Dysprosium, an extensive entropy survives down to very low temperatures. The system remains disordered, yet not in the same way as at high temperature: the disordered phase at low temperatures is in fact endowed with an emergent (gauge) symmetry, very much akin to the one of a solenoidal magnetic field. As in the case of topological order, this low temperature phase does not allow for an immediate LG description, and new techniques need be developed in order to investigate its properties. Lacking a Landau-Ginzburg description, the very bases of a conventional approach to phase-ordering kinetics no longer apply. The aim of this proposal is to fill in this gap, and investigate how order emerges in these new, exotic phases of matter, and how this reflects in the dynamics of its defects. Starting from specific case studies, encompassing both classical and quantum systems, this project will be first concerned with addressing outstanding questions in the field. For example, understanding the non-conventional relaxation and response properties recently observed in experiments on frustrated magnetic materials; as well as investigating the characteristic time scales in topological quantum computing, where issues of preparation, protection, and braiding operations are closely related to the dynamics of topological defects. Once a sufficient body of system-specific knowledge has been developed, the priority of the project will shift towards developing a comprehensive framework of phase-ordering kinetics for this type of systems, which is currently missing in the literature.

了解相变中秩序如何出现以及相应缺陷的行为长期以来一直引起凝聚态物理学和宇宙学等不同领域的兴趣。然而，迄今为止的大部分工作都与相变有关，这些相变允许根据局部有序参数进行 Landau-Ginzburg (LG) 描述。近年来，人们发现了大量摆脱 LG 范式的理论模型和实验系统。例如，在量子霍尔系统中，拓扑序在低温下表现为新兴的对称性，而不是破缺的对称性，并且无法通过局部可观测量来检测。在受阻磁体中，例如钬和镝的稀土钛酸盐，在非常低的温度下仍存在大量的熵。该系统仍然是无序的，但与高温下的方式不同：低温下的无序相实际上被赋予了一种新兴的（规范）对称性，非常类似于螺线管磁场的对称性。与拓扑顺序的情况一样，这种低温相不允许立即进行 LG 描述，需要开发新技术来研究其特性。由于缺乏朗道-金兹堡描述，传统相序动力学方法的基础不再适用。该提案的目的是填补这一空白，并研究秩序如何在这些新的、奇异的物质相中出现，以及这如何反映在其缺陷的动态中。该项目从具体案例研究开始，涵盖经典系统和量子系统，首先关注解决该领域的突出问题。例如，了解最近在受挫磁性材料实验中观察到的非常规弛豫和响应特性；以及研究拓扑量子计算中的特征时间尺度，其中准备、保护和编织操作问题与拓扑缺陷的动态密切相关。一旦开发了足够的系统特定知识，该项目的优先事项将转向为此类系统开发相序动力学的综合框架，而目前文献中缺少该框架。