CAREER: A Versatile Quantum Simulator for Fermionic Ordering

该职业奖支持开发一种新颖而通用的“量子模拟器”，旨在更好地理解固体材料的特性。除了密度和弹性等属性外，材料还具有导电性和磁性等特性，这些特性源于将原子聚集在一起的密集电子气体的基本量子力学行为。材料的一些复杂和技术上重要的特性，如超导性和磁性，只能用量子理论来理解。不幸的是，量子力学对这些特性的中心地位意味着用经典计算设备模拟它们要么无效，要么效率低下。该奖项支持另一种方法，其中获奖者和他的学生正在开发一个模拟器，能够利用原子的量子特性对材料的底层物理进行建模。为了在锂原子中产生量子效应，他们需要同时将原子冷却到绝对零度以上百万分之一度，并使它们表现得像固体材料一样。学生们将使用一组激光使原子减速以达到冷却的目的，另一组激光将原子固定在适当的位置。对这个奖项至关重要的是，包括获奖者在内的科学家们已经开发出一种技术来震动固定的原子，这迫使它们模拟比以前可能的更大范围的材料。该奖项将进一步加深对技术相关材料的科学见解，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外，该奖项还支持亚特兰大地区的高中生和教师在夏季在实验室工作，使用机械和电子（“机电一体化”）自动化工具，以提高实验室的生产力。所获得的最先进实验室设置的技能和知识将用于为高中物理实验室开发类似的工具。该奖项支持使用激光冷却的超冷锂进行材料量子模拟的新方法。材料中许多有争议的重要细节都与费米表面有关，费米表面是导电电子所在的地方。该项目将采用振荡光学晶格，这可以在很大程度上控制费米表面的形状。因此，费米曲面将被调整为支持或不支持某些类型的秩序。关于这些不同形式的秩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，从一个很好理解的显微镜模型生成，可以直接与理论进行比较。该项目团队将在超冷锂原子气体中使用共振光学晶格振动来调整费米表面形状。该项目的目标包括促进具有显著动量依赖性的相互作用，在颈部闭合（Lifshitz）跃迁中展示两个合并的费米表面，并在没有晶格声子模式存在以提供替代机制的“干净”场景中创建套接驱动的密度波形成模型。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。

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.