Collaborative Research: Cold Rydberg Atoms

合作研究：冷里德伯原子

• 批准号: 1607377
• 负责人: Michael Noel
• 金额: $ 34.35万
• 依托单位: Bryn Mawr College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1607377&HistoricalAwards=false
• 关键词: Collaborative; Research; Cold; Rydberg; Atoms

The goals of this project are twofold: first, to understand and control the movement of energy among strongly connected groups of atoms, and second, to improve an experimental technique for measuring the energy distribution among these atoms. These general goals are present in many areas of science (for example, in the study of the transport of energy in metals) but they are often difficult to realize for the simple reason that solids are densely packed with atoms and typically opaque. This work will be done in an "ultracold gas" of atoms that are cooled so that they move slowly like the atoms in a solid, but are at low density. Collections of these atoms are transparent and can be probed and controlled with lasers. If the outer electrons in these atoms are excited to high energy levels, then the atoms can exchange energy in ways that are similar to other quantum systems. Using a combination of simulation and experimental imaging techniques, the transport of energy will be measured. In this way, the project aims to create and study atomic systems that will yield insight into both fundamental quantum mechanics and the behavior of materials. The second goal of this project concerns a widely used experimental technique in which the energy level of an electron is measured by using a rapidly increasing electric field to rip off, or ionize, the outermost electron from the atom. The stripped electron is accelerated to a detector and the resulting signal is characteristic of the electron's original energy level. However, the ionization process is complex and nearby energy levels produce signals which are indistinguishable. This project will precisely shape the electric field pulse so that the signals from closely spaced energy levels can be distinguished, making new experiments possible in many areas of atomic physics.In this project, the valence electron of ultracold rubidium atoms in a magneto-optical trap is excited to a weakly bound state of high principle quantum number, or Rydberg state. Both the spatial distribution of the atoms and the internal states to which they are excited are precisely controlled. The atoms in such a sample exchange energy through a dipole-dipole interaction. Building upon earlier work implementing "state selective field ionization" with two parallel cylinders of atoms excited to two different Rydberg states, other geometries and state distributions will be explored. As the electron's amplitude traverses the many avoided crossings on the way to ionization it splits due to Landau-Zener transitions and spreads throughout many Stark levels, complicating the identification of the original electronic energy level. Previous attempts at manipulating the electron's path to ionization have focused on coarsely determining the slope of the electric field ramp. Since there are hundreds of avoided crossings on the way to ionization, a genetic algorithm will be used to design the electric field ramp. In addition, recent simulations have revealed the possibility of observing the anisotropic nature of the dipole-dipole interaction as well as Anderson localization.

该项目的目标有两个：首先，了解和控制强连接原子团之间的能量运动，其次，改进测量这些原子之间能量分布的实验技术。 这些总体目标存在于许多科学领域（例如，在金属能量传输的研究中），但它们通常难以实现，原因很简单，因为固体中原子密集且通常不透明。这项工作将在原子的“超冷气体”中完成，这些原子被冷却，使它们像固体中的原子一样缓慢移动，但密度较低。这些原子的集合是透明的，可以用激光探测和控制。如果这些原子中的外层电子被激发到高能级，那么原子就可以以类似于其他量子系统的方式交换能量。结合模拟和实验成像技术，将测量能量的传输。 通过这种方式，该项目旨在创建和研究原子系统，从而深入了解基本量子力学和材料行为。该项目的第二个目标涉及一种广泛使用的实验技术，其中通过使用快速增加的电场从原子中剥离或电离最外层的电子来测量电子的能级。剥离的电子被加速到检测器，产生的信号是电子原始能级的特征。然而，电离过程很复杂，附近的能级会产生难以区分的信号。该项目将精确地塑造电场脉冲，以便能够区分来自紧密间隔能级的信号，从而使原子物理许多领域的新实验成为可能。在该项目中，磁光陷阱中的超冷铷原子的价电子被激发到高原理量子数的弱束缚态，即里德伯态。原子的空间分布和它们被激发的内部状态都受到精确控制。这种样品中的原子通过偶极-偶极相互作用交换能量。在早期工作的基础上，利用两个平行的原子圆柱体激发到两种不同的里德堡态来实现“态选择性场电离”，其他几何结构和态分布也将被探索。当电子的振幅在电离过程中穿过许多避免的交叉点时，它会由于朗道-齐纳跃迁而分裂，并扩散到许多斯塔克能级，从而使原始电子能级的识别变得复杂。先前操纵电子电离路径的尝试主要集中于粗略确定电场斜坡的斜率。由于电离途中有数百个避免的交叉点，因此将使用遗传算法来设计电场斜坡。此外，最近的模拟揭示了观察偶极子-偶极子相互作用的各向异性性质以及安德森局域化的可能性。