Low energy electrodynamics of strongly interacting disordered systems: quantum phase transitions and many-body localization

强相互作用无序系统的低能电动力学：量子相变和多体局域化

• 批准号: 1508645
• 负责人: Norman Armitage
• 金额: $ 36.76万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1508645&HistoricalAwards=false
• 关键词: Low; energy; electrodynamics; strongly; interacting

Nontechnical description:It is hardly an exaggeration that most of what we know about physical systems comes from their response to perturbations at their characteristic frequencies. For instance, the fundamental tone of a plucked violin string depends on the length of the string, the tension in it, and its thickness. This is true from the acoustics of a violin to the energies of atoms. Unfortunately the natural frequency scales of many solid materials fall in a spectral range, which has been prohibitively difficult to access technically until recently. This project takes advantage of recent dramatic technical advances in THz and microwave spectroscopy to characterize the natural frequency scales of disordered solids. Material systems like superconductors, which can conduct electricity without resistance and various insulating states are being studied. The investigations performed herein give essential information to develop new materials with important technological implications. These technological developments are coupled to a broad initiative in education and outreach. The work is of particular educational value to students owing to the low frequency electrodynamics techniques that are employed and which are finding broad application in research and private industry. Public outreach activities in the form of the Johns Hopkins Physics Fair is also being realized. Technical description:Interactions, disorder, and their interplay is a central theme of modern condensed matter physics. This project is exploring two areas of intense recent interest where strong interactions and disorder conspire to create exotic low temperature states of quantum matter: the 2D superconductor insulator quantum phase transition and the phenomena of ``many-­body localization". They are being investigated by a number of novel low energy electrodynamic probes available in the PI's group. The 2D superconductor-­insulator transition (2D SIT) is a paradigmatic example of a quantum phase transition (QPT) -­ a topic of much interest in the condensed matter physics. Recent advances in low temperature microwave spectroscopies are being exploited to provide the first true dynamic information about this phase transition in thin superconducting (InO) films. The phenomena of many-­body localization is also being investigated. Recently Basko, Aleiner, and Altshuler demonstrated that for systems with strong enough disorder, localization can prevent energy or particle transport, so that the system fails to equilibrate and to be its own heat bath. This implies that (in the absence of delocalized degrees of freedom like phonons) there should be a finite temperature localization transition. We are investigating the relaxation dynamics of both electron glass systems and disordered Ising chains and among other things looking for changes in the THz relaxation as function of optical pump parameters.

非技术描述：我们对物理系统所知道的大多数知识都不是夸张的，因为它们在其特征频率下对扰动的响应。例如，小提琴弦的基本音调取决于弦的长度，其中的张力及其厚度。从小提琴的声学到原子的能量，这是正确的。不幸的是，许多固体材料的固有频率尺度位于光谱范围内，直到最近才能在技术上很难进入。该项目利用了最近在THZ和微波光谱方面的巨大技术进步来表征无序固体的固有频率尺度。像超导体这样的物质系统可以在没有阻力的情况下进行电力，并且正在研究各种绝缘状态。本文进行的调查提供了重要的信息，以开发具有重要技术意义的新材料。这些技术发展与教育和宣传方面的广泛倡议相结合。由于采用的低频电子技术并在研究和私营业中发现广泛的应用，这项工作对学生具有特别的教育价值。也正在实现以约翰·霍普金斯物理博览会形式的公共外展活动。技术描述：相互作用，混乱及其相互作用是现代冷凝物理物理学的核心主题。该项目正在探索两个强烈感兴趣的领域，在这些领域中，强烈的相互作用和混乱共同创造了量子问题的异国情调的低温状态：2D超导体绝缘子量子相变和``多体性定位''的现象。它们正在由PI小组中许多新颖的低能动力问题进行了研究。 2D超导体 - 绝缘体转变（2D SIT）是量子相变（QPT）的范式示例 - 对凝结物理学引起的极大兴趣的话题。正在探索低温微波光谱的最新进展，以在薄超导（INO）膜中提供有关此相变的第一个真实动态信息。也正在研究多体定位的现象。最近，Basko，Aleiner和Altshuler证明，对于具有足够障碍的系统，定位可以防止能量或颗粒传输，因此该系统无法平衡并成为其自身的热浴。这意味着（如果没有像声子一样的自由度），应该有有限的温度定位过渡。我们正在研究电子玻璃系统和无序的伊斯丁链的松弛动力学，以及其他希望随着光泵参数功能而改变THZ松弛的变化。