Resonant many-electron dynamics on helium

二维（2D）电子系统是现代物理学的核心兴趣。这些系统的参数可以以可控的方式变化，从而可以在可控的环境中探索各种各样的量子多体现象。不仅在基础物理学，而且在纳米技术和量子信息科学中，理解这些系统仍然是进步的主要动力。液氦表面的电子是实验发现的第一个二维电子系统，它们仍然是已知最原始的二维系统。在低温下，超流氦的表面非常干净，没有几乎所有其他材料系统中不可避免的缺陷和缺陷。放置在超流体表面附近的电子会被束缚在超流体表面上，并漂浮在距离表面约10纳米的真空中。它们展示了多体量子动力学的丰富方面。最吸引人的一个方面是系统的灵活性和可调性。通过改变电子的密度和系统的几何形状，可以有效地改变电子之间相互作用的影响。这项研究工作的目的是利用现有的控制来研究凝聚态物理的基本问题。核心兴趣是不同量子系统之间相互作用的相互作用，以及这种相互作用如何影响远离热平衡的电子动力学。没有确立这种动态背后的一般原则。由于氦上的电子系统是如此原始，它是研究耦合量子系统的独特工具。本工作将运用现代实验和理论物理的各种工具来揭示该系统的基本特征。氦上的电子系统也是一个理想的候选者，可以整合到量子设备中，并有可能开发出新的量子技术。在这方面特别感兴趣的是量子信息科学中使用的设备。由于这些特点，氦上的电子也是培养对基础科学和QIS技术感兴趣的学生的理想平台。技术摘要：这项实验和理论联合研究的目的是了解液氦上多电子系统的共振动力学。这些非平凡的动力学是由氦表面的强电子关联和电子系统与量子激发的相互作用产生的。这项研究将解决这样的问题：如果系统被逐出热平衡，这种相互作用是如何改变系统的行为的。具体而言，实验和理论工作将：(1)研究高频激发下的线性和非线性共振响应，目的是了解在强直流场驱动下Wigner晶体中强相关和多体极化效应的相互作用，该效应有效地增强了电子与氦激发的耦合；（ii）探索晶体相中电子迁移率的巨大非线性的本质，以及量子波动对结晶的影响，使用能够计数经过它的单个电子的单电子晶体管；(3)利用压电表面声波研究这些波与电子系统的等离子体模式之间的共振相互作用，并研究高频电子迁移率；（iv）研究多电子系统中的量子涨落和经典涨落如何影响面内磁场中子带间电子吸收的光谱，该磁场耦合了面内和面外运动，使系统模拟了具有受控电子-声子耦合的色中心的光学响应。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。

Non-Technical Abstract:Two-dimensional (2D) electron systems are of central interest for modern physics. The parameters of these systems can be varied in a controllable way, enabling the exploration of a wide variety of quantum many-body phenomena in a controlled setting. Understanding these systems continues to be a major driver for progress, not only in fundamental physics, but also in nanotechnology and quantum information science. Electrons on the surface of liquid helium were the first two-dimensional electron system discovered experimentally, and they still stand out as the most pristine known 2D system. Superfluid helium at low temperatures functions as a fantastically clean surface without defects and imperfections that are unavoidable in almost all other material systems. Electrons placed near this superfluid surface become bound to it and float in vacuum about 10 nanometers above the surface. They exhibit rich aspects of many-body quantum dynamics. One of the most attractive aspects is the flexibility and tunability of the system. The effects of the interaction between electrons can be effectively modified by changing their density and the geometry of the system. This research work aims to use the available controls to study fundamental problems of condensed-matter physics. Of central interest is the interplay of interactions between different quantum systems and how this interplay affects the electron dynamics away from thermal equilibrium. No general principles underlying such dynamics have been established. Because the system of electrons on helium is so pristine, it is a unique tool for the studies of coupled quantum systems. This work will use various tools of modern experimental and theoretical physics to reveal the basic features of the system. The system of electrons on helium is also an ideal candidate for incorporating into quantum devices and to potentially developing novel quantum technologies. Of particular interest in this respect are devices used in quantum information science. Because of these features electrons on helium are also an ideal platform for training students interested in fundamental science and QIS technologies.Technical Abstract:The goal of this joint experimental and theoretical effort is to understand the resonant dynamics of the many-electron system on liquid helium. These non-trivial dynamics result from the interplay the strong electron correlations and the interaction of the electron system with the quantum excitations of the helium surface. The research will address the question of how this interplay modifies the behavior of the system if it is driven away from thermal equilibrium. Specifically, the experimental and theoretical work will (i) study the linear and nonlinear resonant response to high-frequency excitation with the goal to understand the interplay of the strong correlations and the many-body polaronic effect in a Wigner crystal driven by a strong dc field which effectively strengthens the electron coupling to the helium excitations; (ii) explore the nature of the giant nonlinearity of the electron mobility in the crystalline phase and the effect of quantum fluctuations on the crystallization using a single-electron transistor able to count individual electrons as they move past it; (iii) utilize piezoelectric surface acoustic waves to investigate resonant interaction between these waves and plasmonic modes of the electron system and to study the high-frequency electron mobility; and (iv) investigate how quantum and classical fluctuations in the many-electron system affect the spectrum of the inter-subband electron absorption in an in-plane magnetic field that couples in-plane and out-of-plane motion, making the system mimic the optical response of color centers with controlled electron-phonon coupling.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.