Potassium Atoms in 2D Triangular Superlattice

我们对材料理解的进步推动了先进技术的发展。考虑到一种材料是由特定选择的原子元素以特定的晶体形式组成的，我们试图了解材料在电导、热传导、磁化等方面的宏观特性。这种理解通常是从数值模拟中获得的。然而，一种新的材料科学探索范式正在出现：量子模拟。在这种新方法中，通过创建材料的物理模拟来理解材料的性质，即一个高度控制的系统，它遵循与控制真实材料相同的微观规则，但是物理性质可以很容易地调整和测量。在这个项目中，研究小组将使用钾原子气体来模拟材料的特性，将其冷却到极低的温度，并将其捕获在几个激光束相交处产生的规则结构中（光学晶格）。这种光学晶格中超冷原子气体的运动模拟了晶体中电子的运动。通过拍摄原子气体的高分辨率图像，该团队将获得可以指导新材料设计的见解。参与该项目的学生将在不断扩大的量子信息科学领域获得宝贵的培训。该项目的具体科学重点是几何挫折和平面带在人工超冷原子和固态材料中的作用。超冷钾原子将被放置在几种几何形状的光学晶格中，包括蜂窝晶格和kagome晶格。这两种晶格都支持包含平带的能带结构，即能量不随准动量变化的宏观简并态。该团队将利用钾的费米子同位素40-K进行实验，以探测和验证这些带的平坦性，探索平坦带对流动费米子热力学的影响，并研究费米子在平坦带光学晶格中的金属态、铁磁性态、电荷密度波调制态和超导态的可能性。这项工作的发现将推进我们对出现在平带和重费米子材料中的复杂电子相的认识。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。

Advanced technologies are fueled by advances in our understanding of materials. Given that a material is composed of a specific selection of atomic elements in a specific crystalline form, we seek to understand what are the macroscopic properties of the material in terms of electrical and heat conduction, magnetization, and so on. This understanding is often obtained from numerical simulation. However, a new paradigm is emerging for the exploration of materials science: quantum simulation. In this new approach, properties of a material are understood by creating a physical simulacrum of the material, i.e. a highly controlled system that obeys the same microscopic rules as those governing the real material, but a system in which physical properties can be readily tuned and measured. In this project, the research team will simulate the properties of materials using a gas of potassium atoms, cooled to extremely low temperatures, and trapped within a regular structure produced at the intersection of several laser beams (an optical lattice). The motion of the ultracold gas of atoms in this optical lattice mimics the motion of electrons in a crystal. By taking high-resolution images of the atomic gas, the team will gain insight that can guide the design of new materials. Students engaged in the project will receive valuable training in the expanding field of quantum information science. The specific scientific focus of this project is the role of geometric frustration and flat bands in artificial ultracold atomic and also solid state materials. Ultracold potassium atoms will be placed within optical lattices of several geometries, including the honeycomb lattice and the kagome lattice. Both these lattices support a band structure that includes flat bands, i.e. a macroscopic degeneracy of states in which the energy does not vary with quasi-momentum. The team will conduct experiments using the fermionic isotope of potassium, 40-K, in order to probe and verify the flatness of these bands, explore the implication of flat bands on the thermodynamics of itinerant fermions, and study the possibility of metallic, ferromagnetic, charge-density-wave modulated, and superconducting states of fermions in flat-band optical lattices. The findings of this work will advance our knowledge of complex electronic phases that arise in flat-band and heavy-fermion materials.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.