Phase Transitions and Non-equilibrium Dynamics in Homogeneous Quantum Gases

均质量子气体中的相变和非平衡动力学

• 批准号: EP/N011759/1
• 负责人: Zoran Hadzibabic
• 金额: $ 140.67万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FN011759%2F1
• 关键词: Phase; Transitions; Non; equilibrium; Dynamics

Atomic gases cooled to less than a millionth of a degree above absolute zero temperature offer flexible experimental systems for fundamental studies of quantum mechanical effects. In particular they offer excellent test-beds for theories of many-body phenomena, such as Bose-Einstein condensation and superfluidity, which arise from the collective behaviour of many interacting particles. Over the past two decades, studies of many-body physics with ultracold atomic gases have been very successful. The resulting improved understanding of the fundamental principles of quantum mechanics is promising to also lead to many practical applications, including the development of novel materials, navigation instruments, and platforms for quantum information processing. A complete understanding of many-body physics, necessary for such developments, must include both equilibrium and non-equilibrium phenomena, and in the latter respect ultracold atomic gases offer some significant experimental advantages. Specifically they feature relatively long characteristic timescales (milliseconds to seconds), which allow for time-resolved studies of non-equilibrium processes.Traditionally, an important difference between "conventional" many-body systems, such as liquid helium and solid-state materials, and ultracold gases has been that the former are usually spatially uniform, while the latter were produced in bowl-like harmonic traps. This difference can sometimes be addressed using the so-called local density approximation (LDA), which assumes that the gas density varies slowly in space. However, for studies of some very important problems this is a serious hindrance. In particular, LDA breaks down close to phase transitions between different states of matter, where the particles become correlated over very large distances, and where some of the most interesting non-equilibrium effects also emerge. Recently, our group has made a major breakthrough in the field of ultracold atoms by creating first quantum gases in an essentially uniform trapping potential of an optical-box trap. This allows for closer connections with both other many-body systems and the theoretical calculations, and has opened up completely new research possibilities. It has already led to an important advance in the studies of non-equilibrium many-body physics, namely the most direct confirmation so far of the Kibble-Zurek theory of the dynamics of continuous phase transitions, which has implications as far reaching as understanding the formation of large structures in the early universe.Under this Fellowship we will focus on fully capitalising on these exciting new developments. We will perform a comprehensive study of non-equilibrium phenomena in a homogeneous Bose gas with dynamically tuneable interactions, and will also collaborate with two other internationally leading groups, at College de France and MIT, to extend these studies to low-dimensional systems and Fermi gases. This will cement the UK's leadership in the emerging field of homogeneous quantum gases and more generally enhance the UK's position in the highly competitive field of ultracold atoms.

原子气体冷却到比绝对零度高出不到百万分之一度的温度，为量子力学效应的基础研究提供了灵活的实验系统。特别是，它们为多体现象的理论提供了极好的试验台，例如玻色-爱因斯坦凝聚和超流，这些理论是由许多相互作用的粒子的集体行为产生的。在过去的二十年里，利用超冷原子气体进行多体物理的研究非常成功。由此产生的对量子力学基本原理的理解也有望导致许多实际应用，包括开发新材料、导航仪器和量子信息处理平台。对多体物理的完整理解是这种发展所必需的，必须同时包括平衡和非平衡现象，而在后一方面，超冷原子气体提供了一些显著的实验优势。具体地说，它们具有相对较长的特征时间尺度(毫秒到秒)，这使得对非平衡过程的时间分辨研究成为可能。传统上，液氦和固态材料等传统的多体系统与超冷气体之间的一个重要区别是，前者通常在空间上是均匀的，而后者是在碗状的谐波陷阱中产生的。这种差异有时可以用所谓的局部密度近似(LDA)来解决，它假设气体密度在空间中缓慢变化。然而，对于一些非常重要的问题的研究，这是一个严重的障碍。特别是，LDA在物质不同状态之间的相变附近分解，在那里粒子在非常长的距离上变得相互关联，并且一些最有趣的非平衡效应也出现了。最近，我们团队在超冷原子领域取得了重大突破，在光盒陷阱的基本均匀囚禁势中创造了第一个量子气体。这允许与其他多体系统和理论计算建立更紧密的联系，并开辟了全新的研究可能性。它已经导致了非平衡多体物理研究的一项重要进展，即迄今为止最直接地证实了Kibble-Zurek关于连续相变动力学的理论，这一理论的意义深远到理解早期宇宙中大结构的形成。在这项研究中，我们将专注于充分利用这些令人兴奋的新发展。我们将对具有动态可调谐相互作用的均匀玻色气体中的非平衡现象进行全面的研究，并将与法国学院和麻省理工学院的另外两个国际领先小组合作，将这些研究扩展到低维系统和费米气体。这将巩固英国在新兴均质量子气体领域的领导地位，更广泛地提高英国在竞争激烈的超冷原子领域的地位。

项目成果

Observation of first and second sound in a BKT superfluid

• DOI: 10.1038/s41586-021-03537-9
• 发表时间: 2021-06-10
• 期刊: NATURE
• 影响因子: 64.8
• 作者: Christodoulou, Panagiotis;Galka, Maciej;Hadzibabic, Zoran
• 通讯作者: Hadzibabic, Zoran

Can Three-Body Recombination Purify a Quantum Gas?

三体复合可以纯化量子气体吗？

• DOI: 10.1103/physrevlett.123.020405
• 发表时间: 2019
• 期刊: Physical review letters
• 影响因子: 8.6
• 作者: Dogra LH

Universal equation of state for wave turbulence in a quantum gas

• DOI: 10.1038/s41586-023-06240-z
• 发表时间: 2022-12
• 期刊: Nature
• 影响因子: 64.8
• 作者: Lena H. Dogra;G. Martirosyan;T. Hilker;Jake A. P. Glidden;Jivr'i Etrych;Alec Cao;Christoph Eigen;Robert P. Smith;Z. Hadzibabic

Universal equation of state for wave turbulence in a quantum gas.

量子气体中波湍流的通用状态方程。

• DOI: 10.17863/cam.96640
• 发表时间: 2023
• 作者: Dogra L

Universal Scaling Laws in the Dynamics of a Homogeneous Unitary Bose Gas

均质酉玻色气体动力学中的通用标度定律

• DOI: 10.48550/arxiv.1708.09844
• 发表时间: 2017
• 作者: Eigen C