EAGER: SUPER: Light-Induced Room-Temperature Superconductivity at Light Pressure

该奖项支持利用光诱导和探测超导性的理论和实验研究以及教育。在常规超导体中，在足够低的温度下，电子形成一种集体量子力学状态，具有不寻常的特性，包括无电阻导电的能力。超导性通常发生在看似极端的条件下，要么出现在非常低的温度下，一些常见的气体是液体，要么出现在非常高的压力下，接近行星核心深处的压力，就像最近对轻元素氢基化合物的证明那样。然而，最近激光物理学的实验进展表明，光和压力一样，可以作为一种“旋钮”来控制材料的电子行为，这表明在更高的温度或更接近环境条件的适度压力下获得超导性的另一种惊人的可能性。该项目的中心目标是利用量身定制的光照射来研究和控制超导化合物的电子特性。虽然传统的超导性在稳定的平衡状态下得到了很好的研究，但超导体中电子对强外场（如光）的响应仍然知之甚少，并且构成了这一理论和实验结合努力的主要焦点。该项目涉及理论模型的发展，以预测轻元素超导体在晶格振动的目标激发下脱离平衡的响应。pi将重点关注被称为富勒化物和氢化物的含碳和含氢材料。一个具体的目标是绘制路径，利用这些振动模式作为压力的替代品，推动从绝缘或金属状态到超导状态的转变。实验将涉及光谱学测量，作为与激光脉冲击中材料时间同步的时间函数。了解这些反应可以帮助指导理论建模，并有助于设计下一代电子设备。这个项目除了标准的教授课堂教学和博士后和学生的指导外，还包括一些活动。pi正在开发新的课程和新的推广方法，将量子材料广泛地介绍给STEM学生和公众。特别是，第一代大学本科生将参与研究问题，使他们对超导量子材料的现代研究有一种感觉。技术总结：该奖项主要关注光在光元素量子材料中诱导超导性的应用。虽然非常规铜超导体在环境条件下保持着最高超导转变温度的记录，但最近的一系列实验证明了轻元素传统超导体的高转变温度。这些范围从富勒化物到氢化物，在压力下具有具有里程碑意义的近室温超导性。虽然这些材料的超导性需要极高的压力，但最近对铜酸盐、有机电荷转移盐和氢化物进行的一系列开创性实验表明，光脉冲照射原则上可以提供一种替代方法，以诱导长寿命的超导特征脱离平衡。该项目的目标是在理论上和实验上证明，光可以有效地替代外部压力的作用，并在大大降低的压力和高温下诱导非平衡超导状态。为此，pi将对两类化合物（富勒化物和氢化物）进行理论建模和光泵太赫兹探针实验。对于前者，一个关键的目标是实验演示和理论描述光诱导绝缘体-超导体跃迁在Mott-Jahn-Teller绝缘体中失去平衡和在高温下，重点是通过声子的选择性光激发来模拟外部压力的作用。对于后者，pi的目的是证明在压力下氢化物的光诱导超导性。为了实现电子配对的可控增强，pi将从理论上和实验上研究这些材料中声子谱的目标激发和非谐波的作用。该项目的成功将代表对远离平衡的量子相的理解的进步，并可能为在环境条件下实现轻元素超导开辟新的研究方向。教育贡献包括教学和学习活动的整合，使K-12学生和公众能够在研究实验室之外看到宏观量子现象，并提高他们对所涉及的STEM领域的认识。这些活动包括指导博士后和第一代大学本科生，以及与富兰克林研究所科学博物馆合作，在现场进行演示，并将视频录制为K-12学生的交互式虚拟学习程序。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARYThis EAGER award supports theoretical and experimental research, and education on using light to induce and probe superconductivity. In conventional superconductors at sufficiently low temperature, electrons form a collective quantum mechanical state with unusual properties including the ability to conduct electricity without resistance. Superconductivity typically often occurs under seemingly extreme conditions, appearing either at very low temperatures where some common gases are liquids or, as recently demonstrated for light-element hydrogen-based compounds, under very high pressures approaching those found deep in the core of planets. However, recent experimental advances in laser physics suggest that light, like pressure, can act as a kind of "knob" to control the electronic behavior of materials, suggesting a striking alternative possibility of attaining superconductivity at much higher temperatures or more modest pressures approaching ambient conditions. The central goal of this project is to leverage tailored irradiation with light to study and control electronic properties of superconducting compounds. While conventional superconductivity is well-studied in the steady state of equilibrium, the response of electrons in superconductors to strong external fields such as a light remains less understood and constitutes the main focus of this combined theoretical and experimental effort. This project involves the development of theoretical models to predict the response of light-element superconductors driven out of equilibrium by targeted excitation of crystal lattice vibrations. The PIs will focus on classes of carbon and hydrogen bearing materials known as fullerides and hydrides. A specific aim is to chart pathways to utilize these vibrational modes as a substitute for pressure, to drive transformations from an insulating or metallic states to a superconducting state. Experiments will be performed involving optical spectroscopy measurements as a function of time synchronized to the time the laser pulse hits the material. Understanding the responses could help guide theoretical modeling and help in the design of future generation of electronic devices. This project includes several activities beyond standard professorial classroom teaching and mentoring of postdocs and students. The PIs are working on new course development and new outreach methods that will be a broad introduction of quantum materials to the STEM students and the general public. Particularly, first-generation college undergraduates will be involved in research problem to give them a sense of modern research in superconducting quantum materials.TECHNICAL SUMMARYThis EAGER award focuses on the use of light to induce superconductivity in light-element quantum materials. While unconventional cuprate superconductors hold the record for highest superconducting transition temperature at ambient conditions, a series of recent experiments demonstrated high transition temperatures in light-element conventional superconductors. These range from the fullerides to hydrides with landmark near-room-temperature superconductivity under pressure. While superconductivity in these materials requires extremely high pressures, recently a series of seminal experiments on cuprates, organic charge-transfer salts, and hydrides suggest that irradiation with optical pulses can in principle provide an alternative way to induce long-lived superconducting signatures out of equilibrium.The goal of this project is to demonstrate theoretically and experimentally that light can effectively be a substitute in the role of external pressure and induce a non-equilibrium superconducting state at much reduced pressures and high temperatures. To this end, the PIs will perform theoretical modeling and optical-pump terahertz-probe experiments on two classes of compounds, the fullerides and hydrides. For the former, a key aim is the experimental demonstration and theoretical description of a light-induced insulator-superconductor transition in the Mott-Jahn-Teller insulator out of equilibrium and at elevated temperatures, with emphasis on mimicking the role of external pressure through selective optical excitation of phonons. For the latter, the PIs aim to demonstrate light induced superconductivity in hydrides under pressure. To achieve a controlled enhancement of electronic pairing, the PIs will investigate theoretically and experimentally, targeted excitation of the phonon spectrum in these materials and the role of anharmonicities.The success of this project will represent an advance in the understanding of quantum phases driven far out of equilibrium and may open new research directions towards achieving light-element superconductivity at ambient conditions. Educational contributions include the integration of teaching and learning activities that will enable K-12 students and the general public to see macroscopic quantum phenomena outside of research laboratories and to raise their awareness of the STEM fields involved. These activities include mentoring postdocs and first-generation college undergraduate students, as well as working with the Franklin Institute Science Museum to perform demos onsite and record the videos into interactive virtual learning programming for K-12 students.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.