Sympathetic Cooling and Collisions of Atomic and Molecular Ions with Ultracold Atoms

利用离子与第二种(超冷)中性原子(如钠)的碰撞，研究了俘获原子和分子离子的共鸣冷却，这些中性原子以前已经被激光冷却到绝对零度以上不到1/1000度。这项研究的重点是作为冷却机制的极低能离子-中性原子碰撞，实验上对此知之甚少。对经典(牛顿)和量子(薛定谔-海森堡)散射的边界进行了新的探索。所研究的离子-中性相互作用是非常普遍的，涉及到离子电场对中性伙伴的极化(电荷分离)；然后极化的中性原子反过来强烈吸引离子。分子(和分子离子)很难直接激光冷却，因此这项工作将打开应用于太阳系和星际空间的一般能量交换过程，控制接近零开尔文的离子-分子放热反应，在晶格中产生分子离子的维格纳晶体，离子的精确光谱，超精密的原子和分子离子时钟，以及潜在的涉及捕获离子阵列的量子计算机或量子存储寄存器。该项目使用一种特殊的离子-中性混合陷阱(MOT和Paul陷阱组合)来重叠碱金属原子云和各种离子(例如，Ca+、Na2+、Na+)，并能够观察冷却速度和由此发生的反应。这项基础研究涉及原子物理、分子物理、频率标准、空间物理和天体物理、量子信息和记忆及其许多应用。康涅狄格大学的原子、分子和光学物理(AMO)研究目前有10名在职教员和约38名研究生，他们通过个人研究、与同行的互动、每周研究研讨会和座谈会、学者访问、公共讲座和社区推广，接受涉及所有这些领域的广泛教育。研究成果经常在会议上发表。PI的一名物理专业本科生量子力学的学生现在正在参与这个项目的博士级研究。三名本科生暑期学生和两名来自海德堡大学的交换生参与了这项活动。鼓励本科生参加相关自主学习项目。该项目的学生接受了广泛的基本实验物理技术的教育，包括超高真空、激光冷却和捕获、光学、激光光谱学、离子操纵和探测等。

Sympathetic cooling of trapped atomic and molecular ions is investigated by using ion collisions with a second (ultracold) species of neutral atoms (e.g. sodium) which have previously been laser cooled to less than 1/1000th degree above absolute zero. This research focuses on very low energy ion-neutral atomic collisions as the cooling mechanism, about which very little is known experimentally. The boundaries of classical (Newtonian) and quantum (Schroedinger-Heisenberg) scattering are explored in new ways. The ion-neutral interaction under study is very general, involving the polarization (charge separation) of the neutral partner by the electric field of the ion; the polarized neutral atom then acts back to strongly attract the ion. Molecules (and molecular ions) are very difficult to laser cool directly, so this work should open up applications to general energy exchange processes in the solar system and interstellar space, control of ion-molecule exothermic reactions near zero Kelvin, generation of Wigner crystals of molecular ions in a lattice, precision spectroscopy of ions, ultraprecise atomic and molecular ion clocks, and potentially, quantum computers or quantum memory registers involving arrays of trapped ions. The project uses a special hybrid ion-neutral trap (MOT and Paul trap combination) to overlap clouds of alkali-metal atoms and various kinds of ions (e.g. Ca+, Na2+, Na+) and to allow observation of the rates of cooling and reactions that occur as a result. This basic research is relevant to atomic physics, molecular physics, frequency standards, space physics and astrophysics, quantum information and memories and their many applications. Atomic, molecular and optical physics (AMO) research at the University of Connecticut currently involves 10 active faculty and ~38 graduate students who receive a broad education involving all these areas, through their individual research, interaction with peers, weekly research seminars and colloquia, visits from scholars, public lectures and community outreach. Research results are frequently presented at conferences. One of the PI's students in undergraduate quantum mechanics for physics majors is now involved in PhD-level research on this project. Three undergraduate summer students, along with two exchange students from the University of Heidelberg have been involved. Undergraduates are encouraged to participate in related independent study projects. Students on the project receive a broad education in basic experimental physics techniques, including ultrahigh vacuum, laser cooling and trapping, optics, laser spectroscopy, ion manipulation and detection, etc.