RUI: Topological Excitations in Spinor Bose-Einstein Condensates

长期以来，人类一直对对称着迷，这是任何照镜子或仔细观察自己左手和右手的人都熟悉的概念。事实上，对称是一个基本的组织原则，出现在每一个科学学科中。在物理学中，对称性通常表现在拓扑学方面，或者研究形状和结构如何可能或不可能连续地相互变形。正如2016年诺贝尔奖所承认的那样，拓扑学最近已成为现代物理学中一个重要且日益相关的主题。在不同的物理系统中共享的拓扑特征允许互补的研究，即使这些系统是非常不同的。例如，类似的物理学既可以在最高能量的巨型粒子加速器中研究，也可以在最冷温度的台式仪器中研究。这项研究的核心是超冷环境，它是一种稀释气体，冷却到绝对零度以上几百亿分之一度，在这一点上，它发展出的特性使它成为一种控制良好的“宇宙”，在这种宇宙中，可能会召唤出类似于“真实”宇宙中可能出现的粒子，或者，也许更有趣的是，可能不会出现。该项目将研究这些类粒子现象的产生和时间演化，包括点状单极子和被称为“skyrmions”和“knots”的扩展粒子。这样的实验可以提供对许多不同拓扑系统的现象和行为的洞察，并有助于基于它们的操纵和控制的新兴技术。该科学项目还将通过为几名积极进取的本科生以及一名研究生研究员提供技术和科学培训机会，加强前沿实验研究与本科教育之间的关系。在这些方面，它有助于下一代公民科学家的教育。类粒子拓扑结构在物理学中无处不在，出现在宇宙学、粒子物理学和凝聚态物理学等领域。它们可以表现出惊人的持久性，因为它们的特征是守恒的拓扑电荷。超流体，如稀气玻色-爱因斯坦凝聚体，为在高度控制的环境中研究这些激发提供了新的和令人兴奋的机会。超流体的基本对称性（和磁相）决定了它能支持什么样的拓扑激励。这个实验研究项目检查了自旋为1和自旋为2的玻色-爱因斯坦凝聚体中的三维拓扑激发，包括单极子、结和skyrmions。自旋-1实验将探索激发态产生后的时间演化。自旋-2实验将从创建和探索更广泛的可用磁相允许的拓扑激发开始，并回答有关其时间演化的类似问题。通过将冷凝液暴露于随时间变化的磁场和光场中，将产生激发，随后将使用已建立的成像技术对超流体进行仔细检查，以确定其特征。这些结果有望直接有助于我们对拓扑激发的科学理解，这些拓扑激发在物理学的许多分支中都有出现。该科学项目还将通过为几名积极进取的本科生以及一名研究生研究员提供技术和科学培训机会，加强前沿实验研究与本科教育之间的关系。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。

Humans have long had a fascination with symmetry, a concept familiar to anyone who has glanced in a mirror or contemplated their left and right hands. Indeed, symmetry is a fundamental organizing principle that appears in every scientific discipline. In physics, symmetries often manifest themselves in terms of topology, or the study of how shapes and structures may - or may not - be deformed continuously into one another. Topology has recently emerged as an important and increasingly relevant topic in modern physics, as recognized by the 2016 Nobel Prize. Shared topological features in different physical systems permit complementary studies, even when those systems are extremely different. For example, similar physics can be studied both in giant particle accelerators at the highest energies and in tabletop apparatus at the coldest temperatures. The ultracold environment central to this research is a dilute gas cooled to tens of billionths of a degree above absolute zero, at which point it develops properties that make it into a kind of well-controlled "universe" into which may be summoned analogues of particles that might - or, perhaps more interestingly, might not - appear in the "real" universe. This project will study the creation and time-evolution of these particle-like phenomena, including point-like monopoles and extended particles known as "skyrmions" and "knots." Such experiments can provide insight into the phenomena and behavior of many different topological systems, and contribute to emerging technologies based on their manipulation and control. The scientific program will also enhance the relationship between cutting-edge experimental research and undergraduate education by providing technological and scientific training opportunities for several highly motivated undergraduates, as well as for a graduate student researcher. In these ways it contributes to the education of the next generation of citizen-scientists.Particle-like topological structures are ubiquitous in physics, appearing in cosmology, particle physics, and condensed-matter physics, among others. They can exhibit a surprising degree of persistence, as they are characterized by a conserved topological charge. Superfluids, such as dilute-gas Bose-Einstein condensates, provide new and exciting opportunities to examine these excitations in highly-controlled environments. The underlying symmetries (and magnetic phases) of a superfluid determine what kinds of topological excitations it can support. This experimental research program examines three-dimensional topological excitations within spin-1 and spin-2 Bose-Einstein condensates, including monopoles, knots, and skyrmions. The spin-1 experiments will explore the time evolution of the excitations following their creation. The spin-2 experiments will begin by creating and exploring the topological excitations permitted by the wider variety of available magnetic phases, and answer similar questions about their time-evolution. The excitations will be created by exposing the condensate to time-dependent magnetic and optical fields, and will be subsequently characterized by close examination of the superfluid using established imaging techniques. The results are expected to contribute directly to our scientific understanding of topological excitations across the many branches of physics in which they appear. The scientific program will also enhance the relationship between cutting-edge experimental research and undergraduate education by providing technological and scientific training opportunities for several highly motivated undergraduates, as well as for a graduate student researcher.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.