CAREER: The Effect of State-Mixing Interactions on the Rydberg Excitation Blockade

该项目的目标是研究“里德堡激励封锁”。原子将被冷却到极低的温度，并进入被称为里德堡态的高能态。在里德堡理论中，最外层的电子(或原子的负电荷分量)在围绕原子核(或原子核)的极大轨道上运行。由于这些大的轨道，里德堡态的原子具有相对于其自然或基态原子的性质被夸大的性质。里德堡原子的一个这样的性质是，当它们相隔很远的距离时，即使它们没有净电荷，它们也会相互作用很强。通常，当激光照射到一组原子上时，每个原子中最外层的电子很容易被提升到里德堡态。然而，多个里德堡原子之间的相互作用会导致这种激发被抑制或“阻止”，并导致产生的里德堡原子比其他情况下产生的更少。这种对激发的抑制可能有助于将单个原子用作计算机中的“比特”(“中性原子量子计算”)。量子计算机有可能给数据安全和加密带来革命性的变化。本项目将侧重于使里德堡激发封锁的作用变得不那么有效的过程(状态混合作用)。从本质上讲，如果一个人试图用激光把原子放入一个给定的里德堡态，原子就会混合成其他态。这种混合“打破了封锁”，并导致了不受欢迎的大量里德堡原子。本研究的目的是量化状态混合相互作用降低阻塞效率的程度，了解产生混合的物理机制，并研究导致最佳激发阻塞的实验参数。了解这些问题将允许其他研究人员在开发量子计算机时以最大限度地减少不必要的影响的方式使用封锁。该项目还涉及到一个重要的教育部分。PI将为不同的群体开发教育模块，范围从普通教育学生到高级物理学生。PI还将研究元认知练习对物理入门课堂中问题解决成绩的影响。所有工作将在一所以本科为主的大学完成，其中有相当一部分第一代大学生。里德堡激发封锁是一种高激发原子之间强烈相互作用抑制激光激发的过程，是最近一系列实验成果的核心。有人提出，Förster共振附近的多粒子Rydberg态之间的耦合导致的态混合相互作用，可能会在其他有利条件下损害激发抑制的有效性。然而，在实验上，封锁被破坏的程度一直是未知的，因为大量的状态混合总是伴随着共振附近的改进封锁。在这个项目中，态混合降低阻塞效率的程度将使用磁光囚禁中Rydberg原子的态选择场电离光谱来量化。这项工作将有助于更好地理解导致状态混合增强的物理机制。此外，该项目还将对Förster共振附近最佳封锁的实验条件进行系统研究。PI将为一门普通教育课程设计一个关于激光冷却和陷阱的教学模块，以及一个关于表征磁光陷阱中的超冷原子云的高级实验室实验。

The goal of this project is to study the "Rydberg excitation blockade." Atoms will be cooled to extremely low temperatures and put into high energy states called Rydberg states. In Rydberg states the outermost electron (or the negatively charged component of an atom) travels in extremely large orbits around the nucleus (or the core of an atom). Because of these large orbits, atoms in Rydberg states have properties which are exaggerated relative to the properties of atoms in their natural, or ground state. One such property is that Rydberg atoms interact strongly with each other when separated by large distances, even though they have no net charge. Normally, when a laser is shined on a group of atoms, the outermost electron in each atom is readily promoted to Rydberg states. However, the interactions among multiple Rydberg atoms causes this excitation to be suppressed, or "blocked," and leads to the creation of fewer Rydberg atoms than would otherwise be created. This suppression of excitation may help enable the use of single atoms as the "bits" in computer ("neutral atom quantum computing"). Quantum computers have the potential to revolutionize data security and encryption. The present project will focus on processes which make the Rydberg excitation blockade function less effectively (state-mixing interactions). Essentially, if one tries to put atoms into a given Rydberg state using a laser, the atoms will mix into other states. This mixing "breaks the blockade" and leads to an undesirably large number of Rydberg atoms. The goals of the present research are to quantify the extent to which state mixing interactions reduce the blockade efficiency, to understand the physical mechanism which gives rise to the mixing, and to study the experimental parameters which lead to the best excitation blockade. Understanding these issues will allow other researchers to use the blockade in a way that minimizes unwanted effects when developing a quantum computer. The project also involves a significant educational component. The PI will develop educational modules for a diverse group, ranging from general education students to advanced physics students. The PI will also study the impact of metacognitive exercises on problem solving performance in the introductory physics classroom. All work will be done at a primarily undergraduate university with a significant fraction of first-generation college students.The Rydberg excitation blockade, a process whereby strong interactions among highly-excited atoms suppress laser excitation, has been at the heart of an array of recent experimental achievements. It has been suggested that state-mixing interactions, which result from couplings among multi-particle Rydberg states near a Förster resonance, may compromise the effectiveness of the excitation suppression under otherwise favorable conditions. Experimentally, however, the extent to which the blockade is compromised has been unknown, as large amounts of state mixing have always accompanied an improved blockade near resonance. In this project, the extent to which state-mixing reduces the blockade efficiency will be quantified using state-selective field ionization spectroscopy of rubidium Rydberg atoms in a magneto-optical trap. This work will lead to a better understanding of the physical mechanism responsible for enhanced state-mixing. Additionally, the project will include a systematic study of the experimental conditions for the best blockade near a Förster resonance. The PI will design an eduational module on laser cooling and trapping for a general education course as well as an advanced laboratory experiment on characterizing an ultracold atom cloud in a magneto optical trap.