Quantum Many-Body Physics in Spin-Orbit Coupled Bose Gases

一般观众摘要：许多技术上重要的材料特性，如金属的导电性，可以通过研究材料中单个粒子(例如电子)的行为来了解。然而，一些新的材料性质，如超导和磁性，取决于粒子之间的相互作用。当这种粒子间的相互作用很强时，可能会出现无法用单粒子图像解释的有趣性质。此外，自旋-轨道耦合(SOC)--粒子的自旋和运动之间的相互作用--在一系列现象中发挥着关键作用。粒子间相互作用和SOC之间的相互作用可能导致新的量子材料，这为拓扑量子计算机和无耗散电子学等先进技术带来了希望。由于不完善和缺乏实验可控性，直接研究这种材料可能是具有挑战性的。该项目旨在建立一个基于原子玻色气体的高度可控的量子模拟器，以探索低维量子流体中由相互作用和SOC/规范场之间的相互作用而产生的新的强关联量子现象。其目的是为设计新材料和发明新的量子器件提供有用的见解。这个项目将加强从事这项工作的实验小组和该领域的理论家之间的合作。此外，该项目将把研究与物理和工程专业的研究生和本科生的教育结合起来。这些学生将在跨学科的环境中学习，获得原子/分子/光学物理、凝聚态物理、量子物理、光子学和电子学等领域的知识和技能。技术观众摘要：实验团队将设计一种原子(RB-87)玻色气体，受到合成规范场和有效自旋轨道耦合(SOC)的影响，这种气体具有基于光学晶格(由激光产生的周期势)和合成空间(利用原子的内态构成)的新几何结构。晶格的存在可以将原子限制在具有可控粒子间相互作用和关联的低维几何中，从而允许研究由相互作用和合成规范场之间的相互作用引起的新的量子多体物理。该项目的一个主要方向是研究具有非平凡几何结构的空间中受规范场约束的原子，并探索此类空间固有的新物理。例如，设计合成磁场穿过合成圆柱面实现了合成霍尔柱，其中出现了具有对称性保护的拓扑带结构的晶格。该计划将研究相互作用对这些拓扑带以及相关的量子输运、动力学和相变的影响。这样的玻色气体还可以在允许增强的和可调的粒子间相互作用的真实空间一维管中制备。作为另一个例子，该团队的目标是沿一维管子制备具有一维SOC的玻色气体，其中真实空间和SOC的尺寸精确匹配将显著增加一维SOC的影响，并增强一维量子涨落，导致新的多体现象。理论上预测SOC和可调谐粒子间相互作用将修正著名的Tonks-Luttinger物理，从而产生例如非Luttinger量子液体。该计划不仅对冷原子研究感兴趣，而且与凝聚态物理有关，例如对相互作用的拓扑物理/超流体和新的低维强关联量子物质的见解。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。

General audience abstract:Many technologically important material properties, such as the conductivity of metals, can be understood by studying the behavior of a single particle (e.g. an electron) in the material. However, some novel material properties, such as superconductivity and magnetism, depend on how particles interact with one another. When such interparticle interactions are strong, intriguing properties that cannot be explained by the single-particle picture may emerge. In addition, spin-orbit coupling (SOC) - the interaction between a particle’s spin and its motion - plays a crucial role in a wide range of phenomena. The interplay between interparticle interactions and SOC may lead to new quantum materials which hold promise for advanced technologies such as topological quantum computers and dissipationless electronics. Directly studying such materials can be challenging because of imperfections and the lack of experimental controllability. This project aims to build a highly controllable quantum simulator based on atomic Bose gases to explore novel strongly correlated quantum phenomena induced by the interplay between interactions and SOC/gauge fields in low-dimensional quantum fluids. The aim is to provide useful insights for designing new materials and inventing new quantum devices. This project will enhance collaborations between the experimental group doing this work and theorists in the field. Further, the project will integrate research with the education of graduate and undergraduate students from both physics and engineering. These students will learn in an interdisciplinary environment and acquire knowledge and skills in such areas as atomic/molecular/optical physics, condensed matter physics, quantum physics, photonics and electronics. Technical audience abstract:The experimental team will engineer an atomic (Rb-87) Bose gas subjected to synthetic gauge fields and effective spin orbit coupling (SOC) (optically generated using Raman coupling) in novel geometries based on optical lattices (periodic potentials created by lasers) and synthetic spaces (constructed using internal states of atoms). The presence of the lattices can confine atoms in low dimensional geometries with controllable inter-particle interactions and correlations, allowing for studying novel quantum many-body physics induced by the interplay between interactions and synthetic gauge fields. One main direction of the project is to study atoms subjected to gauge fields in spaces with nontrivial geometries, and to explore novel physics inherent to such spaces. For example, engineering a synthetic magnetic field threading a synthetic cylindrical surface realizes a synthetic Hall cylinder where a lattice with a symmetry-protected topological band structure emerges. The program will study the effects of interactions on such topological bands and associated quantum transport, dynamics and phase transitions. Such a Bose gas can be further prepared in real-space 1D tubes which allow for enhanced and tunable inter-particle interactions. As another example, the team aims to prepare a Bose gas with 1D SOC along the 1D tubes, where the exact match of the dimension of both the real space and SOC would notably increase the effects of 1D SOC and also enhance the quantum fluctuations in 1D, leading to new many-body phenomena. The interplay between SOC and tunable inter-particle interactions is theoretically predicted to modify the well-known Tonks-Luttinger physics, giving rise to e.g. non-Luttinger quantum liquids. This program is not only interesting for cold atom research, but is also relevant for condensed matter physics, such as insights to interacting topological physics/superfluids and novel strongly correlated quantum matter in low dimensions.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.