Novel measures of thermalization and time-evolution of strongly correlated, disordered, and topological systems by nonlinear THz spectroscopy

通过非线性太赫兹光谱测量强相关、无序和拓扑系统的热化和时间演化的新方法

• 批准号: 2226666
• 负责人: Norman Armitage
• 金额: $ 36万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-02-01 至 2026-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2226666&HistoricalAwards=false
• 关键词: Novel; measures; thermalization; time; evolution

Non-Technical Abstract:If a physical system is shaken, the rate that it returns to equilibrium is an important measure of its physics. In materials, we are used to measuring such rates in the context of their response to small electric and magnetic fields. For instance, the rate that current decays in a metal after an electric field impulse can be related to the width of its low-frequency “Drude” response in its optical conductivity. The rate that polarization decays after polling a liquid with an electric field corresponds to the width of the broad peak in the Debye relaxational functional form. In contrast, the energy relaxation rate is a fundamental rate that governs many processes, but which is unfortunately not measured straightforwardly via conventional electrodynamic measurements using small fields. This proposal concerns the development of measurement tools to probe materials with large THz range fields that can push materials far from equilibrium allowing new parameters to be measured. The systems of interest in this proposal possess unconventional features with regards to their interactions or band structures that will affect energy relaxation in interesting ways. The team will investigate the rates of energy relaxation in a variety of materials with interesting quantum mechanical correlations. This project also includes a broad initiative in education and outreach. The work is of particular educational value in training students with unique skills to prepare them as the work force in high-tech industries. The research team will play active roles in the Johns Hopkins Physics Fair- an outreach activity which brings hundreds of people each year through Hopkins' labs during a Saturday event and exposes them to various physics demonstrations and activities. The team will also give demonstration shows at the Physics Fair and work with under-resourced local schools.Technical Abstract:This is a project to investigate fundamental aspects of energy relaxation, time-evolution, and thermalization in strongly correlated, topological, and disordered systems by new nonlinear “pump-probe” THz spectroscopies. The research team will exploit recent developments in the form of THz range 2D coherent spectroscopy (and its relatives) to get new information about energy relaxation in correlated and topological metals, as well as disordered electron glasses. Measurements will emphasize the extended THz range (here 0.1 - 40 THz [0.4 - 165 meV]) where generally responses target the low energy emergent degrees of freedom, but experiments will use a full complement of photon energies up through the near infrared. This topic of THz range dynamics and nonlinear response of quantum materials is an effectively wide-open area, in which there has been much interest and some theory, but very few experiments. Among other aspects, the team will investigate the rates of energy relaxation in the regime of “Plankian dissipation” in the cuprate superconductors. It has been conjectured that their anomalous properties reflect an intrinsic quantum mechanical bound on the rate of relaxation that arises from maximally allowed inelastic scattering. This has been inferred from the resistivity experiments, among others. The team will shed light on the origin of this remarkable property by probing the interplay of energy relaxation with this bounding scale. Another project that will confront a long-standing challenge in condensed matter physics is the understanding of materials with both strong interactions and strong disorder. The team will investigate the issue of thermalization and time-evolution in the “electron- glass” state of doped semiconductors on the insulating side of the 3D metal-insulator transition. The team will use both the novel technique of THz 2D coherent and THz pump-probe spectroscopy. The mechanism of energy relaxation, both internal to the electron sub-system and coupling to the lattice are expected to be very different in such glasses and the results of this study may have relevance to the lack of thermalization in many-body localized systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术摘要：如果一个物理系统被震动，它恢复平衡的速度是衡量其物理性质的一个重要指标。在材料中，我们习惯于在它们对小电场和磁场的响应的背景下测量这样的速率。例如，在电场脉冲之后，电流在金属中衰减的速率可以与其光学电导率中的低频“德鲁德”响应的宽度有关。在用电场轮询液体之后，极化衰减的速率对应于德拜弛豫函数形式中的宽峰的宽度。相比之下，能量弛豫速率是支配许多过程的基本速率，但遗憾的是，不能通过使用小场的常规电动测量直接测量。 该提议涉及测量工具的开发，以探测具有大THz范围场的材料，该场可以将材料推离平衡，从而允许测量新的参数。 在这个建议中感兴趣的系统具有非常规的功能，关于他们的相互作用或能带结构，将影响能量弛豫有趣的方式。 该团队将研究具有有趣的量子力学相关性的各种材料的能量弛豫速率。 该项目还包括一项广泛的教育和外联举措。这项工作在培养学生的独特技能方面具有特别的教育价值，使他们成为高科技行业的劳动力。该研究小组将在约翰霍普金斯物理博览会上发挥积极作用-这是一项外联活动，每年在周六的活动中通过霍普金斯的实验室吸引数百人，并使他们接触各种物理演示和活动。该团队还将在物理博览会上进行演示，并与资源不足的当地学校合作。技术摘要：这是一个通过新的非线性"泵浦-探测"太赫兹光谱来研究强关联、拓扑和无序系统中能量弛豫、时间演化和热化的基本方面的项目。该研究小组将利用THz范围2D相干光谱（及其相关技术）的最新发展，以获得有关相关和拓扑金属以及无序电子玻璃中能量弛豫的新信息。测量将强调扩展的THz范围（这里为0.1 - 40 THz [0.4 - 165 meV]），其中响应通常针对低能量出射自由度，但实验将使用近红外光子能量的全部补充。量子材料的太赫兹范围动力学和非线性响应是一个非常开放的领域，人们对这一领域的研究兴趣很大，也有一定的理论基础，但实验研究很少。 在其他方面，该小组将研究在铜酸盐超导体的"浮游生物耗散"制度的能量弛豫率。 它已被证实，他们的反常性质反映了内在的量子力学约束的弛豫率，所产生的最大允许的非弹性散射。这已经从电阻率实验等中推断出来。该团队将通过探索能量弛豫与这种束缚尺度的相互作用来揭示这种显着性质的起源。 另一个将面临凝聚态物理学长期挑战的项目是对具有强相互作用和强无序的材料的理解。该团队将研究3D金属-绝缘体过渡绝缘侧掺杂半导体的"电子-玻璃"状态中的热化和时间演化问题。该团队将使用THz 2D相干和THz泵浦探测光谱的新技术。能量弛豫的机制，无论是内部的电子子系统和耦合到晶格预计将是非常不同的，在这样的玻璃和本研究的结果可能有相关性的缺乏热化在多体本地化systems.This奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。