Metastable Trapped Ions for Clockwork and Probing Nuclear Structure

科学家用来了解宇宙的一些最灵敏的探测器实际上是单原子。 为了获得这种灵敏度，带电原子（离子）被单独隔离在真空室中，通过激光冷却到接近绝对零度，并在称为离子阱的电磁场中悬浮。 镱离子，可以说是这类科学中最受欢迎的，可以在一个独特的（而且知之甚少的）“亚稳态”激发态中储存能量多年。 罕见的原子效应已经被预测存在于这种亚稳态中，这应该使它特别适合于建造原子钟和观察原子的微小核的形状。 该计划首次对这些效应进行实验研究，以深入了解这种不寻常状态所提供的高精度测量能力。该计划旨在观察和研究相对未开发（I=5/2）的镱-173同位素的低位2F 7/2状态中存在的两种不寻常特征。 首先，理论上预测173 Yb+的超精细诱导态混合会使2F 7/2态的六个超精细能级中的四个能级的寿命减少大约两个数量级（与171 Yb+相比），达到实验所需的几天水平。 该小组正在测量每个受影响的超精细状态的这种效应，以确定当该系统取代当前的171同位素作为时钟时，交流斯塔克位移系统误差的相应减少将有多大。 其次，该小组正在展示一种测量173 Yb+的2F 7/2态（目前未知）超精细结构的方案。电子态和原子核的大自旋允许这种“原子核的电子显微镜”显示其电磁多极矩的签名的可能性，包括核磁八极，电十六极，甚至可能是磁性32-该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准。

Some of the most sensitive probes scientists have for learning about the universe are in fact single atoms. To access this sensitivity, charged atoms (ions) are individually isolated in vacuum chambers, cooled to nearly absolute zero by lasers, and levitated in electromagnetic fields known as ion traps. Ytterbium ions, arguably the most popular for this type of science, can store energy for years in a unique (and poorly understood) "metastable" excited state. Rare atomic effects have been predicted to exist in this metastable state that should make it particularly good for building atomic clocks and seeing the shape of the atom's tiny nucleus. This program is experimentally studying these effects for the first time to gain insight into the high precision measurement capabilities offered by this unusual state.This program seeks to observe and study two unusual features that have been predicted to exist in the low-lying 2F7/2 state of the relatively unexplored (I=5/2) ytterbium-173 isotope. First, hyperfine-induced state mixing 173Yb+ has been theoretically predicted to reduce the lifetime of four of the six hyperfine levels of the 2F7/2 state by approximately two orders of magnitude (as compared to 171Yb+) to the experimentally-desirable level of a few days. The group is measuring this effect for each affected hyperfine state to determine how large the corresponding reduction in ac Stark shift systematic error will be when this system is used in place of the current 171 isotope as a clock. Second, the group is demonstrating a scheme to measure the (currently unknown) hyperfine structure in the 2F7/2 state of 173Yb+. The large spin of both the electronic state and the nucleus allows the possibility that this "electron microscope for the nucleus" will show signatures of its electromagnetic multipole moments, including the nuclear magnetic octupole, electric hexadecapole, and possibly even the magnetic 32-pole moment.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.