Topological Protection and Non-Equilibrium States in Strongly Correlated Electron Systems

强相关电子系统中的拓扑保护和非平衡态

• 批准号: EP/I031014/1
• 负责人: Peter Wahl
• 金额: $ 704.5万
• 依托单位: University of St Andrews
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FI031014%2F1
• 关键词: Topological; Protection; Non; Equilibrium; States

A paper mbius strip is like a cylinder in which the paper twists as it goes round. It looks looks quite like the simple cylinder, but it cannot be transformed into one without some drastic action such as cutting it with a pair of scissors. The mathematics describing this fact is known as topology. It allows the classification of shapes and objects into sets whose members are fundamentally similar to each other, and fundamentally different from objects in other sets. This seems abstract, and it is. However, abstract concepts can sometimes point the way to futuristic applications of sciences. One of the ambitious dreams of modern physics and electrical engineering is to build a quantum computer, a machine that would function completely differently to today's computers, and be a step-change in technology. In order to do that, one has to harness a property of quantum mechanics called 'coherence', which allows its laws to be realised. In the everyday world, fully coherent systems are extremely rare, because when they couple with everything around them, that environment acts like a source of strong random noise that scrambles the system up. This 'decoherence' is one of the core problems of the field. Ground-breaking theoretical research over the last decade has shown that there might be special classes of quantum system which are topologically distinct from the vast majority of other systems. This means that they will not couple to the environmental noise that is such a problem, and offer a route to overcoming decoherence. The second key issue for an electronics revolution is understanding what happens when you severely disturb even a normal quantum mechanical system. This is called driving it from equilibrium, and is going to be more and more important as we try to make electronics run faster and over smaller distances. We understand equilibrium quantum physics very well, but as soon as we go far from equilibrium we enter unexplored territory.In this Programme, we will address both these issues. Building on a breakthrough which has shown that topology is much more important in modern materials than we had ever suspected, we will perform a series of interlinked projects aimed at establishing which materials are most likely to offer topological protection from decoherence. Although ambitious, this is not an empty dream. Microsoft, who formally support our work, have created an entire research centre in the USA to work towards it. Their efforts are mainly theoretical, while ours will be mainly concerned with concrete experiments both on naturally occurring materials and on specially engineered hybrids. The second thrust of our Programme, non-equilibrium quantum mechanics, will be mostly theoretical work to begin with. Its primary focus will be gaining insights that will be of relevance to futuristic electronics in general, but we believe there is particular value in coupling that work with the investigation of topological effects. Nothing is proven yet, but there are good grounds to think that non-equilibrium systems may themselves ultimately prove to be the best platform for stablising the topological excitations that so many people are seeking.Our work is highly adventurous, and will push back the frontiers of current knowledge. Doing it as a co-ordinated Programme will bring exactly the cross-fertilisation of ideas and techniques, and of experiment and theory, that maximises the chances of success. The scale of a Programme also enables engaging with top international collaborators. In addition to working with Microsoft's research centre, we will exchange ideas and personnel with groups from Harvard, Berkeley, Cornell and Princeton in the USA, Grenoble in France and Tokyo and Kyoto in Japan. Major challenges require this level of global collaboration, which will expose the young people who we will train to the very best minds.

纸带就像一个圆柱体，纸在圆柱体中旋转。它看起来很像一个简单的圆柱体，但如果没有一些剧烈的动作，比如用剪刀剪断它，它就不可能变成一个圆柱体。描述这一事实的数学方法称为拓扑学。它允许将形状和对象分类为成员彼此基本相似、与其他集合中的对象根本不同的集合。这看起来很抽象，事实也的确如此。然而，抽象的概念有时可以为科学的未来应用指明方向。现代物理和电气工程的一个雄心勃勃的梦想是建造一台量子计算机，一台功能与今天的计算机完全不同的机器，并成为技术上的一大进步。为了做到这一点，人们必须利用量子力学的一种称为“相干性”的性质，这使得它的定律得以实现。在日常生活中，完全连贯的系统是极其罕见的，因为当它们与周围的一切耦合时，环境就像一个强烈的随机噪声源，扰乱了系统。这种“退相干”是该领域的核心问题之一。过去十年开创性的理论研究表明，可能存在一些特殊类型的量子系统，它们在拓扑上与绝大多数其他系统截然不同。这意味着它们将不会与环境噪音耦合，这是一个这样的问题，并提供了一条克服消相干的途径。电子革命的第二个关键问题是理解当你严重干扰甚至是正常的量子力学系统时会发生什么。这就是所谓的驱使它脱离平衡，随着我们试图让电子运行得更快、距离更短，这一点将变得越来越重要。我们非常了解平衡量子物理，但一旦我们远离平衡，我们就进入了未知的领域。在这个项目中，我们将解决这两个问题。在一项突破的基础上，我们将进行一系列相互关联的项目，旨在确定哪些材料最有可能提供拓扑保护，使其免受退相干的影响。这一突破表明，拓扑在现代材料中比我们想象的要重要得多。尽管雄心勃勃，但这并不是一个空想。微软正式支持我们的工作，已经在美国建立了一个完整的研究中心来致力于此。他们的努力主要是理论上的，而我们将主要关注在自然材料和特殊工程杂交材料上的具体实验。我们计划的第二个主旨，非平衡量子力学，首先将主要是理论工作。它的主要重点将是获得与未来电子学总体相关的见解，但我们相信，将其与拓扑效应的研究结合起来具有特别的价值。目前还没有任何证据，但有充分的理由认为，非平衡系统本身可能最终被证明是稳定许多人正在寻找的拓扑激发的最佳平台。我们的工作非常冒险，将推动当前知识的前沿。把它作为一个协调的计划来做，将恰恰带来思想和技术以及实验和理论的交叉交融，从而最大化成功的机会。方案的规模也使其能够与顶尖的国际合作者接触。除了与微软的研究中心合作外，我们还将与来自美国的哈佛、伯克利、康奈尔和普林斯顿，法国的格勒诺布尔和日本的东京和京都的团体交流想法和人员。重大挑战需要这种水平的全球合作，这将使我们将培养的年轻人接触到最优秀的人才。

项目成果

Resonant soft X-ray scattering, stripe order, and the electron spectral function in cuprates

铜酸盐中的共振软 X 射线散射、条纹顺序和电子能谱函数

• DOI: 10.1016/j.physc.2012.04.006
• 发表时间: 2012
• 期刊: Superconductivity
• 作者: Abbamonte P

Atomic-scale coexistence of short-range magnetic order and superconductivity in Fe$_{1+y}$Se$_{0.1}$Te$_{0.9}$

Fe$_{1 y}$Se$_{0.1}$Te$_{0.9}$ 中短程磁序与超导性的原子尺度共存

• DOI: 10.48550/arxiv.1711.10389
• 发表时间: 2017
• 作者: Aluru R

Anisotropic impurity states, quasiparticle scattering and nematic transport in underdoped Ca(Fe1-xCox)2As2

• DOI: 10.1038/nphys2544
• 发表时间: 2013-04-01
• 期刊: NATURE PHYSICS
• 影响因子: 19.6
• 作者: Allan, M. P.;Chuang, T-M.;Davis, J. C.
• 通讯作者: Davis, J. C.

Modulated magnetism in PrPtAl

• DOI: 10.1038/nphys3238
• 发表时间: 2015-04-01
• 期刊: NATURE PHYSICS
• 影响因子: 19.6
• 作者: Abdul-Jabbar, Gino;Sokolov, Dmitry A.;Huxley, Andrew D.
• 通讯作者: Huxley, Andrew D.

Identifying the 'fingerprint' of antiferromagnetic spin fluctuations in iron pnictide superconductors

• DOI: 10.1038/nphys3187
• 发表时间: 2014-02
• 期刊: Nature Physics
• 影响因子: 19.6
• 作者: M. Allan;Kyungmin Lee;Andreas W. Rost;Mark H. Fischer;F. Massee;K. Kihou;Chul-Ho Lee;A. Iyo;H. Eisaki;T. Chuang;J. C. Davis;Eun-Ah Kim