External Field Control of Ultracold Atom-Molecule Mixtures: Quantum Collision Dynamics, Chemical Reactions, and Sympathetic Cooling

超冷原子分子混合物的外场控制：量子碰撞动力学、化学反应和交感冷却

• 批准号: 1607610
• 负责人: Timur Tscherbul
• 金额: $ 26.99万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 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: 2016-09-15 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1607610&HistoricalAwards=false
• 关键词: External; Field; Control; Ultracold; Atom

This project aims at the development of a new, rigorous, and computationally efficient quantum scattering methodology for the theoretical description of low-temperature atom-molecule collisions and chemical reactions in the presence of external electromagnetic fields. A new methodology is needed in order to expand the number and variety of molecular species that can be cooled to the ultra-cold temperatures at which quantum phenomena become dominant. Until recently, the range of molecular species available for experiments in the ultra-cold domain has been limited to those diatomic molecules which can be produced by laser-induced binding of ultra-cold alkali-metal atoms. Expanding this range to include more complex molecular species requires the adoption of appropriate cooling techniques, especially so-called sympathetic cooling, by which elastic atom-molecule collisions within an ultra-cold alkali-metal atom "bath" serve to reduce the temperature of the participating molecules. The process of sympathetic cooling is effective providing that inelastic collisions which could internally heat the molecules, or which might expel them from the trapping environment, can be suppressed. The computational requirements for the accurate description of the relevant collisional processes are stringent, because the molecules involved are highly anisotropic, and because the trapping field environment of the molecule is also generally anisotropic. This project will provide much needed theoretical support to experimental groups honing the sympathetic cooling technique. If the technique is successful, it will drastically extend the range of molecular species available in the ultra-cold regime, with far-reaching implications for ultra-cold molecule-based quantum information processing, quantum simulation, controlled chemistry, and fundamental symmetry tests. As a basis for the improved methodology, the total angular momentum representation of molecular scattering states will be used. The methodology will be applied to elucidate the prospects for sympathetic cooling of the experimentally relevant polar molecules CaH, SrF, and SrOH with the alkali-metal atoms Li and Rb in magnetic and magneto-optical traps. The scientists will also explore new scenarios for controlling atom-molecule chemical reactions via tuning molecular Zeeman states, inducing vibrational Feshbach resonances, and applying superimposed electric and magnetic fields. The graduate students supported by this project will get extensive training in quantum scattering theory, molecular physics, numerical analysis, and computer programming, which will allow them to engage in collaboration with leading experimental groups, and gain international recognition for their research. The proposed work connects the fields of atomic and molecular physics and physical chemistry, thereby enhancing research collaborations between the Physics and Chemistry Departments of the University of Navada, Reno.

该项目旨在开发一种新的，严格和计算有效的量子散射方法，用于在存在外部电磁场的情况下对低温原子 - 分子碰撞和化学反应的理论描述。需要一种新的方法来扩大可以冷却到量子现象成为主导地位的超冷温度的分子物种的数量和种类。直到最近，可用于在超冷结构域中实验的分子物种范围限于那些可通过激光诱导的超冷碱金属原子结合而产生的双原子分子。扩展该范围以包括更复杂的分子物种，需要采用适当的冷却技术，尤其是所谓的交感神经冷却，通过该冷却，在超冷碱金属原子“浴”中弹性原子 - 分子碰撞可降低参与分子的温度。同情冷却的过程有效地说，可以抑制可能内部加热分子或可能将它们排出捕获环境的非弹性碰撞。准确描述相关碰撞过程的计算要求非常严格，因为所涉及的分子是高度各向异性的，并且由于该分子的捕获场环境通常也是各向异性的。 该项目将为磨练同情冷却技术的实验组提供急需的理论支持。如果该技术成功，它将极大地扩展超冷方案中可用的分子物种的范围，对基于超冷分子的量子信息处理，量子模拟，受控化学和基本对称性测试的影响深远。作为改进方法的基础，将使用分子散射状态的总角动量表示。该方法将用于阐明在磁性和磁光陷阱中与碱金属原子LI和RB的实验相关的极性分子CAH，SRF和SROH的交感前景。科学家还将探索通过调整分子Zeeman状态来控制原子 - 分子化学反应的新场景，诱发振动式Feshbach共振，并应用叠加的电场和磁场。该项目支持的研究生将获得量子散射理论，分子物理学，数值分析和计算机编程的广泛培训，这将使他们能够与领先的实验组合作，并为其研究获得国际认可。提出的工作将原子和分子物理学和物理化学领域联系起来，从而增强了里诺·纳瓦达大学物理和化学系之间的研究合作。