Interactions With and Between Rydberg Atoms

里德伯原子之间的相互作用

• 批准号: 1404419
• 负责人: Francis Robicheaux
• 金额: $ 22.5万
• 依托单位: Purdue University
• 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: 2014-09-01 至 2018-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1404419&HistoricalAwards=false
• 关键词: Interactions; Between; Rydberg; Atoms

Typical atoms and molecules in a gas are compact and nearly impervious to all but the strongest electric and magnetic fields that can be applied in a laboratory, and they hardly interact with each other except for the rare cases when they pass within tiny distances of each other. Using simple lasers, one of the electrons in an atom or molecule can acquire so much energy that it is only barely bound to the atom or molecule. An atom with such a weakly bound electron is called a Rydberg atom after Johannes Rydberg who gave a mathematical description of the allowed energies. Because the electron is weakly attached to the atom or molecule, its properties can be controlled using modest fields that are easily accessible. Also, the interaction between two or more Rydberg atoms is millions of times larger than is usual which gives interesting atom-atom effects even for a dilute gas.The main technical goal of this project is to calculate the properties of a single Rydberg atom in static electric or magnetic fields or in laser fields and to calculate the properties of many interacting Rydberg atoms. Within the past decade, there have been an increasing number of experimental groups investigating different arrangements of Rydberg atoms or molecules and fields. One of the general goals of this project is to provide understanding of the experimental results and/or to propose new arrangements worth studying. The reason for investigating a Rydberg atom in different fields is that there is nearly full external control of this quantum system so that it is possible to learn what properties of the interaction control how energy and/or particles move within a closed system. There is a similar reason for studying many interacting Rydberg atoms: the flow of energy through a purely quantum is a fundamental question and is worth studying in different situations. Lastly, there have been several proposals to use Rydberg atoms as components in quantum computers and/or as non-linear optical devices. Thus, studies which use state-of-the-art computational techniques could aid in the understanding of the feasibility of these proposals.This project will investigate several situations where the exaggerated electronic properties of Rydberg atoms are the main common feature. Calculations for systems that consist of a single Rydberg atom exposed to strong fields as well as many Rydberg atoms that interact through their large electric dipole moments will be performed. For all of the systems, the group will use either fully quantum or a mixture of quantum and classical methods in the calculations. The main long term goal of this project is to develop theoretical and computational tools that allow the quantitative description of complex quantum phenomena. The calculations proposed involve highly excited states where the many nodes of the wave function allow for complex phenomena or involve many body systems where the correlations between particles lead to nontrivial dynamics. At a basic level, this goal is a fundamental goal of nearly all atomic theory proposals. Thus, the lessons learned in these studies could be of wide interest. Also, understanding these systems could allow for experimental control of complex states and many body systems.There are a couple of projects that investigate how a single Rydberg atom behaves when exposed to strong fields. The first situation is when an atom is exposed to the structured potential that arises in a bottle-beam trap; when the nucleus is off-center, this potential has little symmetry with respect to the nucleus so that nearly all states are mixed together. The second situation is to understand the role that quantum friction (in the form of spontaneous emission) plays in a driven quantum system; this system is interesting because the classical dynamics leads to the oscillator locking to the drive. The classical motion does not decay out of the O-point and, thus, can remain forever with high energy even though 'friction' is present. The projects involving two or more interacting Rydberg atoms focus on separate aspects of this system but invoke similar computational tools and theoretical ideas. One project is to study the kick an atom receives due to Rydberg-Rydberg interactions, especially for blockaded systems. This kick arises due to the finite interaction energy between the atoms and could have implications for quantum computation schemes. Another project is to study Anderson localization in a Rydberg gas: the randomness in the placement of atoms translates into a randomness in the hopping amplitude of an excitation. A goal is to understand how the 1/R3 dependence in the hopping amplitude affects the basic properties of Anderson localization. Another project is to understand the role that near-field versus far-field dipole-dipole interactions play within a Rydberg gas. By systematically varying the types of states participating in the dipole-dipole interaction, one can tune the system from predominantly near-field (states with large principle quantum number) to far-field (states with small principle quantum number). Lastly, calculations of the interaction between two Rydberg atoms with large electric dipole moments aligned along an external electric field and how it affects the relative motion of the atoms will be performed. This will investigate whether it is possible to vary the direction of the electric field in a rapid, time dependent manner so that the atoms form a dynamically stable molecule.

气体中的典型原子和分子是致密的，除了实验室中可以应用的最强电场和磁场之外，几乎不受所有电场和磁场的影响，并且除了在极少数情况下它们在彼此之间的微小距离内通过时之外，它们之间几乎不发生相互作用。 。使用简单的激光，原子或分子中的一个电子可以获得如此多的能量，以至于它几乎无法与原子或分子结合。具有这种弱束缚电子的原子被称为里德伯原子，约翰内斯·里德伯对允许的能量进行了数学描述。由于电子与原子或分子的连接较弱，因此可以使用易于接近的适度场来控制其特性。此外，两个或多个里德伯原子之间的相互作用比通常情况大数百万倍，即使对于稀气体也能产生有趣的原子-原子效应。该项目的主要技术目标是计算静态中单个里德伯原子的性质电场、磁场或激光场，并计算许多相互作用的里德伯原子的性质。在过去的十年中，越来越多的实验小组研究里德伯原子或分子和场的不同排列。该项目的总体目标之一是提供对实验结果的理解和/或提出值得研究的新安排。在不同领域研究里德伯原子的原因是，这个量子系统几乎完全受到外部控制，因此可以了解相互作用的哪些属性控制能量和/或粒子在封闭系统内的移动方式。研究许多相互作用的里德伯原子也有类似的原因：通过纯量子的能量流动是一个基本问题，值得在不同情况下研究。最后，已经有一些建议使用里德伯原子作为量子计算机和/或非线性光学设备的组件。因此，使用最先进的计算技术的研究可以帮助理解这些建议的可行性。该项目将研究几种以里德伯原子夸大的电子特性为主要共同特征的情况。将计算由暴露于强场的单个里德伯原子以及通过其大电偶极矩相互作用的许多里德伯原子组成的系统。对于所有系统，该小组将在计算中使用全量子方法或量子和经典方法的混合方法。该项目的主要长期目标是开发能够定量描述复杂量子现象的理论和计算工具。所提出的计算涉及高度激发态，其中波函数的许多节点允许复杂的现象，或涉及许多物体系统，其中粒子之间的相关性导致不平凡的动力学。在基本层面上，这个目标是几乎所有原子理论提案的基本目标。因此，这些研究中吸取的教训可能会引起广泛的兴趣。此外，了解这些系统可以对复杂状态和许多身体系统进行实验控制。有几个项目研究单个里德伯原子在暴露于强场时的行为。第一种情况是当原子暴露于瓶束陷阱中产生的结构势时；当原子核偏离中心时，该势相对于原子核几乎不对称，因此几乎所有状态都混合在一起。第二种情况是了解量子摩擦（以自发发射的形式）在受驱动的量子系统中所起的作用；这个系统很有趣，因为经典动力学导致振荡器锁定到驱动器。经典运动不会在 O 点之外衰减，因此即使存在“摩擦”，也可以永远保持高能量。 涉及两个或多个相互作用的里德伯原子的项目侧重于该系统的不同方面，但引用了类似的计算工具和理论思想。其中一个项目是研究原子由于里德堡-里德堡相互作用而受到的冲击，特别是对于封锁的系统。这种反冲是由于原子之间的有限相互作用能量而产生的，并且可能对量子计算方案产生影响。另一个项目是研究里德伯气体中的安德森定位：原子放置的随机性转化为激发的跳跃幅度的随机性。目标是了解跳跃幅度的 1/R3 依赖性如何影响安德森定位的基本属性。另一个项目是了解近场与远场偶极子-偶极子相互作用在里德堡气体中所起的作用。通过系统地改变参与偶极子-偶极子相互作用的状态类型，可以将系统从主要是近场（具有大主量子数的状态）调整到远场（具有小主量子数的状态）。最后，将计算两个具有沿外部电场排列的大电偶极矩的里德伯原子之间的相互作用，以及它如何影响原子的相对运动。这将研究是否可以以快速、时间相关的方式改变电场的方向，从而使原子形成动态稳定的分子。