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：如果物理系统受到震动，其恢复平衡的速率是其物理特性的重要衡量标准。在材料中，我们习惯于在其对小电场和磁场的响应的背景下测量此类速率。例如，电场脉冲后金属中电流衰减的速率可以与其光学电导率中低频“德鲁德”响应的宽度相关，用电场轮询液体后偏振衰减的速率与之相对应。到宽峰的宽度相比之下，能量弛豫率是控制许多过程的基本速率，但不幸的是，它不能通过使用小场的传统电动测量直接测量。大太赫兹范围的平衡场可以推动材料远离允许测量新参数的系统，其相互作用或能带结构具有非常规的特征，这些特征将以有趣的方式影响能量弛豫。各种材料的能量弛豫率该项目还包括在教育和推广方面的广泛举措，在培养具有独特技能的学生方面具有特殊的教育价值，使他们成为高科技行业的劳动力。约翰·霍普金斯大学物理博览会上的角色——一项外展活动，每年在周六的活动中让数百人参观霍普金斯大学的实验室，让他们接触到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他们合作。资源匮乏的当地学校。技术摘要：该项目旨在通过新型非线性“泵浦探针”太赫兹光谱研究强相关、拓扑和无序系统中的能量弛豫、时间演化和热化的基本方面。研究团队将利用这种形式的最新进展。太赫兹范围的二维相干光谱（及其相关光谱）以获得有关相关金属和拓扑金属以及无序电子玻璃的能量弛豫的新信息，测量将强调扩展的太赫兹范围（此处为 0.1 - ）。 40 THz [0.4 - 165 meV]），通常响应针对低能量涌现自由度，但实验将使用通过近红外的完整光子能量。太赫兹范围动力学和量子材料的非线性响应的主题是。一个广泛的有效开放区域，其中有很多兴趣和一些理论，但在其他方面，该团队将研究铜酸盐“普朗克耗散”状态下的能量弛豫率。据推测，它们的反常特性反映了由最大允许的非弹性散射引起的内在量子力学界限，该团队将揭示超导体的起源。通过探索能量弛豫与这种边界尺度的相互作用，凝聚态物理中面临的另一个长期挑战是理解具有强相互作用和强无序性的材料。该团队将使用太赫兹二维相干光谱和太赫兹泵浦探针光谱技术来解决 3D 金属-绝缘体转变绝缘侧掺杂半导体“电子玻璃”态的热化和时间演化问题。在这种玻璃中，电子子系统内部的能量弛豫机制和与晶格的耦合预计会有很大不同，这项研究的结果可能与多体局域化中缺乏热化有关。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。