CAREER: A Versatile Quantum Simulator for Fermionic Ordering

这一职业奖支持开发一种新颖而多功能的“量子模拟器”，旨在更好地了解固体材料的性质。除了密度和弹性等属性外，材料还具有导电性和磁性等属性，这些属性源于将原子聚集在一起的致密电子气体的量子力学行为。材料的一些种类繁多的复杂性质和技术上的重要性质，如超导和磁性，只能用量子理论来理解。不幸的是，量子力学对这些性质的中心性意味着用经典计算设备模拟它们要么是无效的，要么是低效的。该奖项支持另一种方法，即获奖者和他的学生正在开发一种模拟器，能够使用原子的量子属性来模拟材料的基本物理。为了发挥锂原子中的量子效应，他们需要同时将原子冷却到绝对零度以上百万分之一度以内，并使它们像固体材料一样发挥作用。学生们将使用一套激光使原子减速以实现冷却，并使用另一套激光将原子固定在适当的位置。对这一奖项至关重要的是，包括获奖者在内的科学家们已经开发出一种摇动被钉住的原子的技术，这将迫使它们模拟比以前可能的更大范围的材料。该奖项将进一步科学地洞察与技术相关的材料，并支持新一代学生理解量子相互作用。除了支持研究生的培训，该奖项还支持来自亚特兰大地区的高中生和教师整个夏天在实验室工作，开发机械和电子(机电)自动化工具，以提高实验室生产率。所获得的最先进实验室的技能和知识将用于为高中物理实验室开发类似的工具。该奖项支持一种使用激光冷却、超冷锂对材料进行量子模拟的新方法。材料中许多有争议的重要细节都与传导电子所在的费米面有关。该项目将使用抖动的光学晶格，这允许在很大程度上控制费米面的形状。因此，费米面将被调谐到有利于或不利于某些类型的有序。关于这些不同形式的有序如何竞争或共存的重要问题可以得到回答，并创建复杂的相图，这些相图是从一个众所周知的显微镜模型生成的，可以直接与理论进行比较。该项目团队将使用超冷锂原子气体中的共振光学晶格振动来调整费米表面的形状。该项目的目标包括促进与显著动量相关的相互作用，在颈部闭合(Lifshitz)转变处展示两个合并的费米面，以及在不存在晶格声子模的“干净”场景中创建嵌套驱动的密度波形成模型以提供替代机制。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This CAREER award supports the development of a novel and versatile “quantum simulator” aimed at better understanding the properties of solid materials. In addition to attributes like density and elasticity, materials have properties such as electrical conductivity and magnetism that result from the fundamentally quantum mechanical behavior of the dense gas of electrons holding the atoms together. Some of the wide variety of complex and technologically important properties of materials, such as superconductivity and magnetism, can only be understood using quantum theory. Unfortunately, the centrality of quantum mechanics to these properties means that simulating them with classical computation devices is either ineffective or inefficient. This award supports an alternative approach, wherein the awardee and his students are developing a simulator capable of modeling the underlying physics of materials using the quantum properties of atoms. In order to bring out the quantum effects in lithium atoms, they need to simultaneously cool the atoms to within one millionth of a degree above absolute zero and cause them to act like a solid material. Students will use one set of lasers to slow the atoms down to achieve the cooling, and another set of lasers to pin them in place. Critical to this award, scientists, including the awardee, have developed a technique to shake the pinned atoms, which coerces them into emulating a much larger range of materials than previously possible. This award will further scientific insight into materials of technological relevance, as well as support a new generation of students in understanding quantum interactions. In addition to supporting the training of graduate students, the award supports high school students and teachers from the Atlanta area to work in the lab over the summer on mechanical and electronic (“mechatronic”) automation tools to increase lab productivity. The skills and knowledge of state-of-the-art laboratory set up acquired will be used to develop similar tools for the high school physics lab.This award supports a novel approach to quantum simulation of materials using laser cooled, ultra-cold lithium. Many of the details of debated importance in materials relate to the Fermi surface, where the conduction electrons live. The project will employ shaken optical lattices, which allow a great degree of control over the shape of the Fermi surface. Thereby, the Fermi surface will be tuned to favor or disfavor certain types of order. Important questions about how these different forms of order can compete or co-exist can be answered, and create complex phase diagrams generated from a well understood microscope model that can be directly compared with theory. The project team will use resonant optical lattice shaking in a gas of ultracold lithium atoms to tune the Fermi surface shape. The project goals include facilitating interactions with significant momentum dependence, demonstrating two merging Fermi surfaces at a neck closing (Lifshitz) transition, and creating models of nesting-driven density wave formation in a “clean” scenario where no lattice phonon modes exist to provide an alternate mechanism.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.