Spectroscopic, Collisional, and Laser Cooling Studies of Atomic Gadolinium

原子钆的光谱、碰撞和激光冷却研究

• 批准号: 1404496
• 负责人: Clayton Simien
• 金额: $ 22.96万
• 依托单位: University of Alabama at Birmingham
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-15 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1404496&HistoricalAwards=false
• 关键词: Spectroscopic; Collisional; Laser; Cooling; Studies

A new element will be investigated as a prospective candidate for a next generation optical atomic clock and for laser cooling. Atomic clocks have been instrumental in the advancement of science and technology in the twentieth century, leading to innovations such as global positioning, advance communications, and tests of fundamental particle physics. A next generation optical atomic clock would extend the capabilities of these systems and will enable a renaissance of timing applications such as enhanced security for data routing and communications, advanced earth and space time-based navigation, geophysical surveying, testing Einstein's Theory of General Relativity, and searches for variations in the fundamental constants of the universe. Laser cooling is a technique for which the mechanical action of light is used to reduce the velocity of an atom in a gas. The use of lasers to cool atoms opened up new frontiers in physics ranging from the formation of new states of matter to enabling novel nanotechnologies. The extension of laser cooling to a new atomic species will enable the creation of novel ultracold atomic systems with unique properties and dynamics. The goal of this project is to investigate the atomic physics properties and implement laser cooling of atomic gadolinium for its potential use as an optical frequency standard and as a step to create new research avenues in atomic physics cross-fertilized with condensed matter physics. More specifically, these experiments will use lasers as a probe to determine the influence of external perturbations that limits its accuracy as an atomic clock. In addition, the spectral features of gadolinium will be characterized as a diagnostic tool to determine its cooling limits. This specific milestone will enable a gadolinium optical clock of greater accuracy and the realization of exotic ultracold quantum physics systems. This research program will support and train undergraduate and graduate students to become the next generation of scientists and engineers for fundamental and applied research in Atomic, Molecular, and Optical Physics. This project is an experimental research program directed towards investigating collisional and spectroscopic properties of atomic gadolinium (Gd). Gd is a novel class of atom that has an exotic electronic configuration and large ground state magnetic moment, which allows it to have submerged shell optical clock transitions, ultracold collisions having ground state angular momentum, and exotic quantum gas phases and phenomenon dominated by dipole-dipole forces. In particular, the collision studies involve measurements of collision quenching cross sections, and pressure broadening and shifts of the atomic states and line shapes of the optical clock and laser cooling transitions inside a Gd vapor cell. The objective is to characterize the collision sensitivity of these atomic transitions to give insight into the combined action of electron screening and configurational interactions. In addition, the radiative lifetimes, hyperfine structure, and isotope shifts of identified intercombination laser cooling transitions will be determined using laser induce fluorescence spectroscopy with an atomic beam. The determination of these spectroscopic properties are necessary for implementing narrow-line laser cooling for both bosonic and fermonic isotopes of gadolinium. Narrow-line laser cooling is essential for achieving quantum degeneracy with gadolinium, since its large ground state magnetic moment prevents evaporative cooling in a magnetic trap. In addition, laser cooling and trapping using electric-dipole transitions will be executed to create a magneto-optical trap of gadolinium as a first step towards performing precision measurements, investigating ultracold collision, and for studying atomic dipolar physics.The experimental program will have three categories of broader impacts. First, forbidden transitions of rare earth elements are virtually unexplored. These atomic resonances are well suited as potential candidates for next generation frequency standards, with Q-factors nearly four orders of magnitude larger than current neutral atom clock lines, a suppression of black-body radiations shifts by exponents in the fine structure constant, and reduced sensitivity to collision. Moreover, for Standard Model Physics, these transitions have enhanced sensitivities to variations in the fine structure constant. Second, a laser cooled and trapped gas of gadolinium will have many applications: For nuclear physics, astrophysics, and biomedicine, laser cooled Gd will allow for economizing nuclear fuel consumption, ultrasensitive isotope trace analysis of the element for cosmo-chemical studies and biomedical sample testing respectively. Also with respect to nanostructure fabrication, an ultracold gas of Gd can be used for controlled doping or nanoscale milling to create novel magnetic devices. Third, graduate and undergraduate students who will help perform the proposed experiments will be trained. A goal of this project is to attract and retain more students in Atomic Molecular and Optical physics through the involvement of university students in the proposed experiments. This is augmented by the fact that the University of Alabama at Birmingham (UAB) is a major research institution in the geographical region with an annual enrollment of nearly 18,000 students, and the research project involves the extensive use of lasers that is ideal for capturing a student's imagination. An additional goal is to recruit underrepresented minorities, which represents 25 percent of UAB's student population. Underrepresented minorities represent a large untapped wealth of potential for becoming contributors in the fields of science and engineering. To help address this matter a major plan is to involve minority graduate, undergraduate, and high school students via existing UAB outreach and REU programs to participate in research projects in the Simien Spectroscopy and Laser Cooling group. Furthermore, special outreach activities will be done with the aim to get K - 12 students interested in science and engineering by performing various physics, chemistry, and material science demonstration at local schools in the region.

一种新的元素将被研究作为下一代光学原子钟和激光冷却的潜在候选者。原子钟在20世纪的科学和技术进步中发挥了重要作用，导致了全球定位、先进通信和基本粒子物理学测试等创新。下一代光学原子钟将扩展这些系统的功能，并将实现定时应用的复兴，例如增强数据路由和通信的安全性，先进的地球和空间时间导航，地球物理测量，测试爱因斯坦的广义相对论，以及搜索宇宙基本常数的变化。激光冷却是一种利用光的机械作用来降低气体中原子的速度的技术。利用激光冷却原子开辟了物理学的新领域，从物质新状态的形成到新型纳米技术的实现。将激光冷却扩展到一种新的原子物种将使具有独特性质和动力学的新型超冷原子系统的产生成为可能。该项目的目标是研究原子物理特性，并实现原子钆的激光冷却，以实现其作为光学频率标准的潜在用途，并作为在原子物理学中创建与凝聚态物理学交叉发展的新研究途径的一步。更具体地说，这些实验将使用激光作为探针来确定限制其作为原子钟精度的外部扰动的影响。此外，钆的光谱特征将被表征为确定其冷却极限的诊断工具。这一特殊的里程碑将使钆光钟具有更高的精度，并实现奇异的超冷量子物理系统。该研究项目将支持和培养本科生和研究生成为原子、分子和光学物理基础和应用研究的下一代科学家和工程师。本项目是一个实验研究项目，旨在研究原子钆（Gd）的碰撞和光谱特性。Gd是一类新颖的原子，它具有奇异的电子构型和大的基态磁矩，这使得它具有淹没壳光学时钟跃迁，具有基态角动量的超冷碰撞，以及奇异的量子气相和由偶极-偶极力主导的现象。特别是，碰撞研究涉及碰撞淬火截面的测量，以及Gd蒸气池内原子态的压力增宽和位移以及光学时钟和激光冷却跃迁的线形状。目的是表征这些原子跃迁的碰撞灵敏度，以深入了解电子筛选和构型相互作用的联合作用。此外，将利用原子束激光诱导荧光光谱法测定已确定的互组合激光冷却跃迁的辐射寿命、超精细结构和同位素位移。这些光谱性质的测定对于实现钆的玻色子和铁元素同位素的窄线激光冷却是必要的。窄线激光冷却对于实现钆的量子简并是必不可少的，因为它的大基态磁矩阻止了磁阱中的蒸发冷却。此外，利用电偶极跃迁的激光冷却和捕获将被执行，以创建钆的磁光阱，作为进行精确测量，研究超冷碰撞和研究原子偶极物理的第一步。这个实验项目将产生三种更广泛的影响。首先，稀土元素的禁止过渡几乎没有被探索过。这些原子共振非常适合作为下一代频率标准的潜在候选者，其q因子比当前的中性原子钟线大近四个数量级，在精细结构常数中抑制了黑体辐射的指数位移，并且降低了对碰撞的灵敏度。此外，对于标准模型物理学来说，这些转变增强了对精细结构常数变化的敏感性。其次，激光冷却和捕获的钆气体将有许多应用：在核物理、天体物理和生物医学领域，激光冷却的钆将允许节省核燃料消耗，超灵敏的同位素痕量分析元素，分别用于宇宙化学研究和生物医学样品测试。此外，在纳米结构制造方面，Gd的超冷气体可用于控制掺杂或纳米级铣削以制造新型磁性器件。第三，将对参与实验的研究生和本科生进行培训。该项目的目标是通过让大学生参与拟议的实验来吸引和留住更多的原子分子和光学物理学生。阿拉巴马大学伯明翰分校（UAB）是该地区的主要研究机构，每年招收近18,000名学生，该研究项目涉及广泛使用激光，这是捕获学生想象力的理想选择，这一事实进一步增强了这一点。另一个目标是招收未被充分代表的少数民族，他们占UAB学生总数的25%。未被充分代表的少数民族代表着一笔巨大的未开发的财富，可以成为科学和工程领域的贡献者。为了帮助解决这个问题，一个主要的计划是通过现有的UAB外展和REU计划让少数民族研究生、本科生和高中生参与到Simien光谱和激光冷却小组的研究项目中来。此外，还将在该地区的学校进行各种物理、化学、材料科学示范，以提高K - 12学生对科学和工程的兴趣。