Physics with New Molecular Systems: Quantum Interactions, Cooling, and Applications

新分子系统物理学：量子相互作用、冷却和应用

• 批准号: 1505961
• 负责人: John Doyle
• 金额: $ 48万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1505961&HistoricalAwards=false
• 关键词: Physics; New; Molecular; Systems; Quantum

Atoms are the basic building blocks of nature and their behavior is governed by a microscopic theory of matter called quantum mechanics. Our understanding of nearly everything we see in nature relies on quantum mechanics as applied to atoms and their close cousins, molecules (two or more atoms stuck together by a chemical bond). From humans and other living things to computers and the internet, physical systems can be explained only by knowing how atoms and molecules behave in detail. Yet, although quantum mechanics has been very successful in describing very simple atomic systems, we do not yet know how to apply the theory quantitatively to describe all the phenomena that we see. In particular, to invent new technological and biological substances, we need to understand the quantum mechanics of atoms and molecules better. The eventual goal of much of physics (including atomic physics) is to have a complete understanding of all matter and the tools to invent new types of matter. This project is a step toward developing a detailed quantum understanding of the interactions between atoms and molecules in a gas at a very low temperature. When cooled, the quantum nature of atoms and molecules is greatly amplified, exposing its nature to careful study. The essential experimental approach to this work is to use magnetic trapping of atoms and molecules to study their collisions using laser spectroscopy. The technical method will be to use buffer-gas cooling to form a beam of atoms and molecules, which will be optically pumped into magnetically trapped states as they pass through the trapping region. Half the molecules in the beam are originally in the low-field-seeking quantum state. These molecules lose energy as they approach the magnetic field maximum of the trap, where they will be optically pumped into their high-field-seeking state. These molecules then continue to lose energy as they travel toward the trap center. Near the trap center lasers pump the molecules into their trapped state. Only two photons are scattered in this process and this (along with energy loss as the molecules pass through the trap) leads to irreversible trap loading. We will trap molecules of calcium monofluoride and other small molecules into a magnetic trap using this method. Atoms can also be co-loaded with molecules, at high enough density for evaporative cooling. We will co-load lithium and/or potassium atoms and study collisions between them and the trapped molecules, testing molecular theory and investigating a route toward ultracold molecules using sympathetic cooling. Spectroscopy will reveal both the state distribution of the molecules, as well as their number and temperature. Investigation of trap loss can be used to study spin-relaxation collisions (for which there is detailed theory for some atom-molecule pairs). The longer term goal of this work is to enable observation of exchange of energy and other phenomena in increasingly complex atom-molecule collisions, starting with diatomic and triatomic molecules. This will add to our fundamental understanding of nature and help science to design new physical systems and new tools for chemistry and biology.

原子是自然的基本基础，其行为受称为量子力学的物质理论的控制。我们对自然界中所见的几乎所有事物的理解都依赖于适用于原子及其近乎堂兄的量子力学，即分子（两个或多个原子被化学键粘在一起）。从人类和其他生物到计算机和互联网，只能通过了解原子和分子如何详细行为来解释物理系统。但是，尽管量子力学在描述非常简单的原子系统方面非常成功，但我们尚不知道如何定量地应用理论来描述我们看到的所有现象。特别是，要发明新的技术和生物学物质，我们需要更好地了解原子和分子的量子力学。许多物理学（包括原子物理学）的最终目标是对所有物质和发明新类型物质的工具有完整的了解。该项目是在非常低温下气体中原子与分子之间相互作用的详细量子理解的一步。冷却后，原子和分子的量子性质会大大放大，使其性质暴露于仔细研究中。这项工作的基本实验方法是使用原子和分子的磁诱捕使用激光光谱研究其碰撞。技术方法将是使用缓冲液冷却形成原子和分子的束，该原子和分子将在通过捕获区域时将其光学地泵入磁性捕获状态。梁中的一半分子最初位于低场寻求量子状态。这些分子在接近陷阱的磁场最大值时会失去能量，在那里它们将光学地泵入他们的高田间寻求状态。这些分子在驶向陷阱中心时继续失去能量。在陷阱中心附近，激光器将分子泵入其被困状态。在此过程中，只有两个光子散布了，并且（随着分子穿过陷阱的能量损失）会导致不可逆的陷阱载荷。我们将使用此方法将单氟钙和其他小分子的钙分子捕获到磁陷阱中。原子也可以与分子共同加载，以足够高的密度进行蒸发冷却。我们将共同负载锂和/或钾原子，并研究它们与捕获分子之间的碰撞，测试分子理论，并使用交感神经冷却研究迈向超低分子的途径。光谱法将揭示分子的状态分布及其数量和温度。对陷阱损失的研究可用于研究自旋 - 浮肿碰撞（对于某些原子分子对有详细的理论）。这项工作的长期目标是能够在日益复杂的原子 - 分子碰撞中观察能量和其他现象的交换，从双原子和三局分子开始。这将增加我们对自然的基本理解，并帮助科学设计新的物理系统和新的化学和生物学工具。