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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/G049394/2
负责人：
Claudio Castelnovo
金额：
$ 21.98万
依托单位：
Royal Holloway University of London
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FG049394%2F2
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.

长期以来，人们一直对凝聚态物理和宇宙学等不同领域感兴趣，了解相变过程中如何出现有序，以及相应缺陷的行为。然而，到目前为止，大多数工作都是关于相变的，这种相变允许用局域有序参数来描述Landau-Ginzburg(LG)。近年来，人们发现了许多脱离LG范式的理论模型和实验系统。例如，在量子霍尔系统中，拓扑有序在低温下表现为一种突现的--而不是破缺的--对称性，并且它不能被局部观察者检测到。在受挫的磁体中，例如稀土钛酸盐中的Ho和Dy，在极低的温度下仍存在大量的熵。系统仍然是无序的，但与高温时的方式不同：低温下的无序相实际上被赋予了一种突现(规范)对称性，非常类似于螺线管磁场的对称性。在拓扑有序的情况下，这种低温相不允许立即进行Lg描述，因此需要开发新的技术来研究其性质。由于缺乏Landau-Ginzburg描述，传统的相序动力学方法的基础不再适用。这一提议的目的是填补这一空白，并研究在这些新的、奇异的物质相中如何出现秩序，以及这如何反映在其缺陷的动力学中。从具体的案例研究开始，包括经典和量子系统，这个项目将首先关注解决该领域的悬而未决的问题。例如，了解最近在受挫磁性材料上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、保护和编织操作与拓扑缺陷的动力学密切相关。一旦发展了足够多的系统特有知识，该项目的重点将转移到为这类系统开发一个全面的相序动力学框架，这是目前文献中所缺少的。