Spin Squeezing and Entanglement in Bose-Einstein Condensates

这项研究将推动量子增强型计量学的最先进水平，在这种计量学中，对时间和频率、电磁场和惯性力等技术上重要的量进行测量，灵敏度接近基本量子理论设定的极限。这项研究的技术分支可能会导致用于导航和磁力测量的精密传感器、原子钟和新兴量子技术，包括量子计算、量子模拟和量子通信。这项研究的主要活动是对冷却到接近绝对零度的超冷原子进行实验研究，在那里它们形成一种独特的量子相干态物质，称为玻色-爱因斯坦凝聚体。这些实验由研究生和本科生进行，他们在先进的实验室技术和量子科学方面获得了重要的专业知识。此外，通过将研究成果纳入课堂讲课、维护一个充满活力的网站、主持实验室参观、访问当地学校和促进关于这项工作的受欢迎的新闻发布，向广大受众传播这项研究。具体地说，这个研究项目将研究具有内部自旋自由度的原子玻色-爱因斯坦凝聚体中的量子压缩和纠缠态。研究使用了限制在光学陷阱中的Rb原子玻色-爱因斯坦凝聚体(BEC)。原子系综内部自旋自由度的动态演化源于与自旋相关的碰撞相互作用，这些相互作用产生了自旋系综的量子关联或纠缠态。这个量子系统非常简单，使得基态和非平衡激发态的演化都可以与理论预测进行定量比较。然而，它提供了一系列丰富的现象，包括自发对称性破坏、纠缠态和非平凡的几何相位。该实验平台提供了一个强大的工具组合来探索重要的主题，包括量子临界现象和大规模纠缠态的产生。这项研究的一个共同主题是有限尺寸效应的作用，这些效应表现在系统的量子涨落中，这些研究将提供对许多物理领域重要的多粒子量子力学基本原理的洞察。这项工作将建立在最近的量子自旋动力学研究的基础上，这些研究包括自旋向列相压缩的测量，动力学稳定性和参数激发的演示，二阶量子相变的高精度研究，以及跨量子临界点激发的Kibble-Zurek普适性的探索。这个奖项反映了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，被认为是值得支持的。

This research will advance the state of the art in quantum-enhanced metrology, in which measurements of technically important quantities such as time and frequency, electro-magnetic fields and inertial forces are made with sensitivities approaching the limits set by fundamental quantum theory. Technological off-shoots of this research could lead to precision sensors for navigation and magnetometry, atomic clocks and emerging quantum technologies, including quantum computing, quantum simulation and quantum communication. The primary activity of the research is experimental investigation of ultracold atoms cooled to near absolute zero temperature where they form a uniquely quantum coherent state of matter known as a Bose-Einstein condensate. The experiments are performed by graduate students and undergraduate students who gain important expertise in the advanced laboratory techniques and quantum science. Additionally, the research is disseminated to a broad audience by incorporating results into classroom lectures, maintaining a dynamic website, hosting laboratory tours, making visits to local schools and facilitating popular press releases about the work. Specifically, this research project will investigate quantum squeezed and entangled states in atomic Bose-Einstein condensates with internal spin degrees of freedom. The investigations employ rubidium atomic Bose-Einstein condensates (BEC) confined in optical traps. The dynamic evolution of the internal spin degrees of freedom of the ensemble of atoms results from spin-dependent collisional interactions that generate quantum correlated or entangled states of the spin ensembles. This quantum system is simple enough so that both the ground state and evolution of non-equilibrium excited states can be quantitatively compared to theoretical predictions. Yet it offers a rich array of phenomena including spontaneous symmetry-breaking, entangled states and non-trivial geometric phases. The experimental platform provides a powerful combination of tools to explore important topics including quantum critical phenomena and the generation of massively entangled states. A common theme of the research is the role of finite size effects that are manifested in the quantum fluctuations of the system, and these studies will provide insight into fundamental principles of many-particle quantum mechanics that are important to many areas of physics. This work will build upon recent investigations of quantum spin dynamics that include the measurement of spin-nematic squeezing, demonstration of dynamical stabilization and parametric excitation, high precision studies of a second order quantum phase transition, and exploration of Kibble-Zurek universality in excitations across a quantum critical point.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.