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

本项目的目标是研究“里德伯兴奋阻断”。“原子将被冷却到极低的温度，并进入高能状态，称为里德伯态。 在里德伯态中，最外层的电子（或原子中带负电荷的部分）以极大的轨道围绕原子核（或原子核）运动。 由于这些大的轨道，里德伯态的原子具有相对于自然或基态原子的性质被夸大的性质。 其中一个性质是里德伯原子在相隔很远时会相互作用很强，即使它们没有净电荷。 通常，当激光照射一组原子时，每个原子中最外层的电子很容易被提升到里德伯态。 然而，多个里德伯原子之间的相互作用导致这种激发被抑制或“阻断”，并导致产生比其他情况下更少的里德伯原子。 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”）。 量子计算机有可能彻底改变数据安全和加密。 目前的项目将集中在过程中，使里德伯激发阻断功能不太有效（状态混合相互作用）。 从本质上讲，如果试图使用激光将原子置于给定的里德堡态，原子将混合到其他状态。 这种混合“打破了封锁”，并导致了大量的里德堡原子。 本研究的目标是量化状态混合相互作用降低阻断效率的程度，了解引起混合的物理机制，并研究导致最佳激发阻断的实验参数。 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小化不必要影响的方式使用封锁。 该项目还包括一个重要的教育部分。 PI将为不同的群体开发教育模块，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入门物理课堂中问题解决表现的影响。 所有的工作都将在一所以本科为主的大学进行，其中有相当一部分是第一代大学生。里德堡激发阻断是一种高度激发的原子之间的强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。 有人认为，状态混合的相互作用，这是由多粒子里德伯态之间的耦合附近的福斯特共振，可能会妥协的有效性，否则有利的条件下，激发抑制。 然而，在实验上，封锁受到损害的程度是未知的，因为大量的状态混合总是伴随着共振附近的改善封锁。 在这个项目中，在何种程度上状态混合降低封锁效率将量化使用磁光阱中的铷里德伯原子的状态选择场电离光谱。 这项工作将导致更好地了解负责增强状态混合的物理机制。 此外，该项目将包括对福斯特共振附近最佳阻断的实验条件进行系统研究。PI将为通识教育课程设计一个关于激光冷却和捕获的教育模块，以及一个关于表征磁光阱中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.