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Coherence in low-energy excitations of magnetic systems

磁系统低能激励的相干性

基本信息

批准号：
EP/D049717/1
负责人：
Andrew Fisher
金额：
$ 45.17万
依托单位：
University College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2006
资助国家：
英国
起止时间：
2006 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FD049717%2F1
关键词：
Coherence low energy excitations magnetic

项目摘要

The effects of quantum physics normally show up only in very small things (such as atoms or molecules). Recently, however, quantum behaviour has shown up in macrosocpic objects, such as magnetic materials. If one takes such a material and subjects it to the magnetic field from an alternating current, one finds that the way it responds is dominated by well-defined excitations that ring quantum-mechanically for surprisingly long times. These new excitations are a little like new particles, emerging from the complex and disordered state of the magnet.Why does this happen? At present, nobody knows. The reason is that we have no theory that can describe precisely which aspescts of a system continue to behave quantum-mechanically as its size is increased. The aim of this project is to provide such a theory, by generalising previous approaches which look at the way other measurable quantities (such as the degree of coordination among the magnetic atoms) change as we look on longer and longer length-scales.Why is this interesting? If these long-lived quantum-mechanical excitations can be properly understood, we will have access to new quantum-mechanical objects with which we can not only test fundamental theories, but which can also act as building blocks for technology. For example, they might be used to represent or process information in new ways.

量子物理的影响通常只出现在非常小的物体上(如原子或分子)。然而，最近，量子行为已经在宏观物体上表现出来，比如磁性材料。如果人们拿出这样一种材料，并将其置于交流电产生的磁场中，人们会发现，它的响应方式是由定义明确的激发主导的，这些激发以量子力学的方式响起了惊人的长时间。这些新的激发有点像新粒子，从复杂无序的磁状态中出现。为什么会发生这种情况？目前，没有人知道。原因是，我们没有理论可以准确地描述一个系统的哪些方面随着其规模的增加而继续以量子力学的方式表现。这个项目的目的是提供这样一个理论，通过概括以前的方法，当我们看越来越长的长度尺度时，这些方法观察其他可测量的量(如磁性原子之间的配位度)的变化方式。为什么这很有趣？如果能够正确地理解这些长期存在的量子力学激发，我们将有机会获得新的量子力学对象，我们不仅可以用它们来测试基本理论，还可以用它们作为技术的基石。例如，它们可能被用来以新的方式表示或处理信息。