Molecular Lattice Clock for Precision Measurements and Ultracold Chemistry

原子和分子科学与有关自然基本定律的大问题之间的联系正在增长。 原子和分子遵循量子物理学的规则，因此具有离散的能态。 控制这些量子态的新技术正在导致新一代的桌面实验，这些实验可以在广泛的可能能量和基本相互作用类型上提供新物理学的一瞥。 这些实验前所未有的范围来自于对原子和分子量子态以及任何不良环境影响的完美控制。 从原子和分子物理学实验中获得的基本见解包括：对那些从时间上看并不相同的过程的严格限制;对自然界几个基本常数的测量和对它们是否真正恒定的检验;寻找尚未被理解但被假设包含宇宙大部分能量的暗能量和暗物质;爱因斯坦的广义相对论的测试，并寻找可能的新的物理力量。 在许多类型的实验方法中，原子钟作为极其精确的测量工具发挥着特殊的作用，有助于解决各种科学问题。 另一方面，分子比原子拥有更多类型的内部运动和量子态，例如，分子成分相对于彼此的振动。 以分子振动为中心机制的时钟可以获得原子钟无法实现的新的基本测量。 近年来，分子冷却和量子态控制研究取得了重大进展。 这使得最先进的分子钟成为可能，该分子钟利用朝向绝对零度冷却的分子，其中精确度和准确度的运动退化几乎被消除。 在该项目中，将开发振动分子晶格钟及其首次科学应用，包括在纳米尺度上测试牛顿引力。 此外，这项工作在计量学、超冷温度下的化学和基础物理学领域之间建立了广泛的联系。在光学晶格中紧密捕获中性分子提供了具有大信噪比的测量，同时消除了导致分子态叠加快速退相干的运动效应。 这项资助的获得者最近的工作导致了基于振动动力学的分子钟的开发，其质量因子Q接近一万亿，与十多年前最好的原子钟相匹配。 实现分子状态不敏感，捕获是这一成功的关键。 这一起点使时钟已经适用于一类新的高精度测量。主要的科学应用是对原子间力的超精确测量。 结合同时开发的最先进的量子化学理论，这种基于时钟的测量应该导致在纳米尺度上对非牛顿引力的最佳限制，同时提供分子量子电动力学的测试。 分子钟还将产生一个独立于模型的测量电子与质子质量比的时间稳定性。 Q的进一步改进取决于对双光子分子光解离过程的理解，这将分子钟与超冷化学领域智能地联系起来。 该项目将实现的分子状态之间的长相干时间与量子信息和分子量子位的多体实验高度相关。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The connection between the science of atoms and molecules and the big questions relating to the fundamental laws of nature is growing. Atoms and molecules obey the rules of quantum physics and thus have discrete energy states. The new techniques of controlling these quantum states are leading to a new generation of table-top experiments that can offer a glimpse of new physics over an extensive range of possible energies and types of fundamental interactions. The unprecedented reach of these experiments arises from an immaculate control of atomic and molecular quantum states as well as of any undesirable environmental influences. The fundamental insights gained from experiments in atomic and molecular physics include the tight constraints on processes that do not appear the same if viewed backwards in time; measurements of several fundamental constants of nature and tests of whether they are truly constant; searches for dark energy and dark matter that are not yet understood but are hypothesized to contain most of the energy of the universe; tests of Einstein's general relativity; and searches for possible new physical forces. Among many types of such experimental approaches, atomic clocks play a special role as extremely precise measurement tools, contributing to diverse scientific questions. On the other hand, molecules possess significantly more types of internal motions and quantum states than atoms, - for example, vibrations of the molecular constituents relative to each other. A clock based on molecular vibrations as its central mechanism can access new fundamental measurements that are out of reach for atomic clocks. Significant progress has recently taken place in molecular cooling and quantum state control. This makes possible state-of-the-art molecular clocks that utilize molecules cooled toward absolute zero, where motional degradation of precision and accuracy is nearly eliminated. In this project, a vibrational molecular lattice clock and its first scientific applications, including tests of Newtonian gravity at nanometer length scales, will be developed. Furthermore, this work makes broad connections between the fields of metrology, chemistry at ultracold temperatures, and fundamental physics.Tightly trapping neutral molecules in an optical lattice affords measurements with a large signal-to-noise ratio while eliminating motional effects that lead to rapid decoherence of the molecular state superpositions. Recent work by the recipients of this grant resulted in the development of a molecular clock based on vibrational dynamics, with a quality factor Q of nearly a trillion, matching the best atomic clocks of just over a decade ago. Realizing molecular state-insensitive, trapping is a key to this success. This starting point makes the clock already applicable to a new class of high-precision measurements. The primary scientific application is for an ultraprecise measurement of an interatomic force. Combined with state-of-the-art quantum chemistry theory developed concurrently, this clock-based measurement should lead to the best limit on non-Newtonian gravity at the nanometer scale, while providing tests of molecular quantum electrodynamics. The molecular clock will also yield a model-independent measurement of the temporal stability of the electron-to-proton mass ratio. Further improvement in Q is contingent on understanding two-photon molecular photodissociation processes, which intellectually connects the molecular clock with the field of ultracold chemistry. The long coherence times between molecular states that will be achieved in this project are highly relevant to quantum-information and many-body experiments with molecular qubits.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.