Spin Squeezing and Entanglement in Bose-Einstein Condensates

这项研究将推动量子增强计量学的发展，在量子增强计量学中，测量技术上重要的量，如时间和频率，电磁场和惯性力，其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强计的精密传感器、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实验研究超冷原子冷却到接近绝对零度的温度，在那里它们形成一种独特的量子相干物质状态，称为玻色-爱因斯坦凝聚态。这些实验是由研究生和本科生进行的，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座、维护动态网站、举办实验室参观、访问当地学校和促进有关工作的流行新闻发布，将研究成果传播给广泛的受众。具体来说，本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态和纠缠态。研究使用了铷原子玻色-爱因斯坦凝聚体（BEC），这些凝聚体被限制在光学阱中。原子系综内部自旋自由度的动态演化是自旋依赖的碰撞相互作用的结果，这些相互作用产生自旋系综的量子相关态或纠缠态。这个量子系统足够简单，因此基态和非平衡激发态的演化都可以定量地与理论预测相比较。然而，它提供了丰富的现象阵列，包括自发对称破缺，纠缠态和非平凡的几何相。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。研究的一个共同主题是在系统的量子涨落中表现出来的有限尺寸效应的作用，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见解。这项工作将建立在最近的量子自旋动力学研究的基础上，包括自旋向列挤压的测量，动态稳定和参数激发的演示，二阶量子相变的高精度研究，以及跨越量子临界点激发的Kibble-Zurek普适性的探索。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 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.