CAREER: Precision Measurements with Ultracold Diatomic Molecules

非技术描述：对“几点了？”这个问题的回答。最终可以追溯到基于原子内部滴答的主时钟。过去，这些主时钟精度的提高使得我们在汽车和智能手机中使用的GPS系统等创新能够在地球上定位我们的位置。未来对时钟的改进有望实现类似的创新，这些创新才刚刚开始想象。目前的项目寻求通过使用分子而不是原子来更准确地跟踪时间来扩大我们可以实现的科学和技术的范围。分子提供了一种基于与原子钟不同的物理基础的量子钟的可能性：原子核振动而不是电子跃迁。由两个原子组成的简单分子将在绝对零度附近产生，并被困在驻波光中，以确保与环境几乎完全隔离。这些锶分子具有非常明确的内部能态，可以用激光进行精确的操纵和探测。这个时钟对宇宙演化过程中可能发生的电子与质子质量比的变化很敏感，对可能出现在纳米尺度上的尚未发现的力也很敏感。技术描述：一种新的基于激光冷却锶原子的超冷双原子分子最近被主要研究人员的研究小组证明。这项工作(基于对这些二聚体的光学捕获、操纵和成像)将使分子物理中的精确测量以及对可能指示标准模型以外的新物理的基本定律的测试成为可能。初步工作表明，通过在激发态和基态下对该分子应用原子晶格钟技术，可以直接测量分子波函数的非绝热科里奥利混合角；这些角对于描述原子连续体附近的弱分子键至关重要。这个项目将进一步刻画这些弱束缚系统从绝热行为到非绝热行为的转变。此外，紧密结合的超冷基态锶二聚体将被创建用于振动光谱，或分子振动时钟。如果更好地理解范德华类型的原子间相互作用的质量标度，这个时钟可能会将纳米级质量依赖力的知识提高几个数量级。当该分子的晶格光谱的系统效应得到更好的表征，并将状态不敏感的晶格俘获作为本项目的一部分进行优化时，该分子钟可以为电子与质子质量比的稳定性设定最佳的模型无关的极限。坚固的分子钟在大地测量、导航和基础科学测试中都有应用。特别努力让来自纽约市当地社区的年轻公立学校学生参与到科学家的日常工作中来。

Non-technical description:The answer to the question "what time is it?" ultimately traces back to master clocks that are based on the internal ticking of atoms. Increasing the accuracy of these master clocks has in the past enabled such innovations as the GPS systems that we use in our cars and smartphones to locate our position on the globe. Future improvements in clocks can be expected to enable similar innovations that are only just beginning to be imagined. The present project seeks to extend the scope of the science and technology we can achieve by keeping track of time ever more accurately, using molecules instead of atoms. Molecules present the possibility of a quantum clock based on different physics than atomic clocks: nuclear vibrations rather than electronic transitions. Simple molecules that consist of two atoms will be created near the temperature of absolute zero and trapped in standing waves of light to ensure nearly complete isolation from the environment. These strontium molecules possess very well defined internal energy states that allow precise manipulation and probing with laser light. This clock is sensitive to variations in the electron-to-proton mass ratio that may occur as the universe evolves, and to yet undiscovered forces that might appear at nanometer scales. Technical description:A new class of ultracold diatomic molecules based on laser-cooled strontium atoms was recently demonstrated by the primary investigator's research group. This work (based on optical trapping, manipulation, and imaging of these dimers) will enable precision measurements in molecular physics as well as tests of fundamental laws that may indicate new physics beyond the Standard Model. Initial work indicates that by applying atomic lattice-clock techniques to this molecule in both the excited and ground states, a direct measurement of the nonadiabatic Coriolis mixing angles of the molecular wavefunctions can be performed; these angles are critical for describing weak molecular bonding near the atomic continuum. This project will further characterize the transition from adiabatic to nonadiabatic behavior in these weakly bound systems. Additionally, tightly bound ultracold ground-state strontium dimers will be created for vibrational spectroscopy, or a molecular vibrational clock. If the mass scaling of the van der Waals type interatomic interaction is better understood, this clock can potentially improve the knowledge of nanometer-scale mass-dependent forces by several orders of magnitude. When the systematic effects of lattice spectroscopy of this molecule are better characterized and state-insensitive lattice trapping is optimized as part of this project, this molecular clock can set the best model-independent limit on the stability of the electron-to-proton mass ratio. Robust molecular clocks have applications in geodesy, navigation, and tests of fundamental science. Special efforts are made to involve young public school students from local New York City neighborhoods and expose them to the day-to-day work of scientists.