Collective Phenomena at the Interface Between the Quantum and Classical Worlds

在原子尺度上，支配世界的法则与支配人类尺度的法则截然不同；也就是量子力学定律。我们在人类尺度上经历的行为是如何从这个潜在的量子世界中产生的，这给科学带来了一些最深刻的问题。这些问题不仅具有根本性的意义，还具有深远的技术含义：随着硅芯片的制造包含越来越多的组件，它们接近量子力学效应开始占主导地位的规模。纳米技术的出现也将带来类似的挑战。本提案中描述的工作旨在以多种方式扩展原子尺度/量子力学行为与人类尺度/经典行为之间过渡的知识。在某些被称为量子临界的系统中，许多量子成分以这样一种方式相互作用，使得群体行为介于量子和经典之间。这些系统还有一个额外的有用特性，即它们的群体行为在很大程度上与小尺度细节无关（这种特性被称为普遍性）。最重要的是，这一特性使我们在理解这些系统方面取得了进展。在这个提议的研究中，我打算探索量子临界行为的极限；它如何应对被强烈地赶出平衡，以及在某些情况下，它如何被其他行为所取代。

On the atomic scale, the world is governed by very different laws from those that operate on the human scale; namely the laws of quantum mechanics. The way in which the behaviour that we experience on the human scale emerges from this underlying quantum world presents science with some of its deepest questions. As well as their fundamental import, these questions have profound technological implications: as silicon chips are made which contain more and more components, they approach a scale where quantum mechanical effects begin to dominate. The advent of nano-technology will bring similar challenges.The work described in this proposal seeks to extend knowledge of the transition between the atomic scale/quantum mechanical behaviour and the human scale/classical behaviour in a number of ways.In certain systems - known as quantum-critical - many quantum constituents interact with one-another in such a way that the group behaviour is part way between quantum and classical. These systems have the additional useful property that their group behaviour is largely independent of small scale details (a property known as universality). This property, above all, has allowed progress to be made in understanding these systems.In this proposed research, I intend to explore the limits of quantum-critical behaviour; how it responds to being driven strongly out of equilibrium and how it may be replaced by alternative behaviour in certain circumstances.