Microscopy of Ultracold Polar Molecules in Optical Lattices

原子或分子等微观粒子的世界受量子力学定律的支配。虽然这些定律描述了我们日常经验中不熟悉的现象，但它们可以用来设计革命性的技术。例如，非常精确的时钟或功能强大的计算机可以解决从药物发现到人工智能等不同领域的棘手问题。在许多应用中利用量子力学的力量的一个关键要求是获得对相互作用的量子粒子的大型系统的微观控制。该奖项支持一种仪器的开发，即一种“分子量子气体显微镜”，它将在数千个分子的气体中实现这种水平的控制。与原子相比，即使是实验中使用的非常简单的分子也表现出丰富的行为。例如，分子在空间中翻滚，组成分子的原子相对于彼此振动。此外，由不同原子组成的分子是“极性”的，其行为很像冰箱磁铁，即使在很远的距离也会产生强烈的相互作用。通过将分子气体冷却到非常低的温度，它们运动的量子性质和它们强烈的相互作用发挥着越来越重要的作用，并导致分子重新排列成不寻常的物质状态。这些状态将直接在单个分子水平上使用分子显微镜进行成像和控制。该项目将进一步加深我们对相互作用量子物质的理解，对设计具有新技术特性的材料具有潜在的影响。它还具有实现基于分子的量子计算平台的潜力。这项研究将在新兴的量子科学领域培养研究生，为他们未来在学术界、工业界和国家实验室的职业生涯做好准备。极性分子的超冷气体在量子计算、精密测量和研究国家控制的化学反应等方面具有广阔的应用前景。最近备受关注的一个应用是多体现象的量子模拟。极性分子之间相互作用的长程和各向异性的特性使得量子模拟能够处理当代凝聚态物理中的各种感兴趣的领域，包括非平衡量子动力学、拓扑物质和量子磁性。这一新兴领域的一个突出挑战是测量和操纵相互作用阵列中单个分子的量子态的能力。该项目将开发显微技术，能够以单点精度提取光学晶格中单个基态分子的位置，并确定它们的旋转态。为此，分子将以状态敏感的方式解离成它们的组成原子，随后将使用成熟的原子量子气体显微镜技术进行检测。该项目还将研究玻色子分子蒸发到量子简并，使用强大的电场来抑制非弹性碰撞。简并分子玻色气体中的强偶极相互作用有望导致新的物质相，包括自组织晶体和分数Mott绝缘体。分子量子气体显微镜将能够直接成像和控制这些阶段及其激发。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The world of microscopic particles like atoms or molecules is governed by the laws of quantum mechanics. While these laws describe phenomena unfamiliar in our daily experience, they can be used to engineer revolutionary technologies. Examples include very precise clocks or powerful computers that can solve intractable problems in diverse fields ranging from drug discovery to artificial intelligence. A key requirement for harnessing the power of quantum mechanics for many applications is gaining microscopic control over large systems of interacting quantum particles. This award supports the development of an instrument, a "molecular quantum gas microscope" that will achieve this level of control in a gas of thousands of molecules. Even the very simple molecules used in this experiment exhibit rich behaviors compared to atoms. For example, molecules tumble in space, and the constituent atoms vibrate relative to each other. In addition, molecules made of different atoms are "polar," behaving much like fridge magnets that interact strongly even at a large distance. By cooling molecular gases down to very low temperatures, the quantum nature of their motions and their strong mutual interactions play an increasingly important role and lead to the rearrangement of the molecules into unusual states of matter. These states will be directly imaged and controlled at the level of individual molecules using the molecular microscope. The project will further our understanding of interacting quantum matter, with a potential impact on designing materials with new technological properties. It also holds the potential for realizing a molecule-based platform for quantum computing. The research will train graduate students in the burgeoning field of quantum science, preparing them for future careers in academia, industry and national labs. Ultracold gases of polar molecules are promising for many applications including quantum computation, precision measurements and studies of state-controlled chemical reactions. One application that has been the subject of much recent attention is the quantum simulation of many-body phenomena. The long-range and anisotropic character of the interactions between polar molecules enables quantum simulations that address a variety of areas of contemporary interest in condensed matter physics including out-of-equilibrium quantum dynamics, topological matter and quantum magnetism. An outstanding challenge in this emerging field is the ability to measure and manipulate the quantum state of individual molecules in an interacting array. This project will develop microscopy techniques that enable the extraction of the positions of individual ground-state molecules in an optical lattice with single-site accuracy and the determination of their rotational state. To that end, molecules will be dissociated in a state-sensitive way into their constituent atoms, which will be subsequently detected using well-developed atomic quantum gas microscopy techniques. The project will also study the evaporation of the bosonic molecules to quantum degeneracy, using a large electric field to suppress inelastic collisions. The strong dipolar interactions in a degenerate molecular Bose gas are expected to lead to novel phases of matter, including self-organized crystals and fractional Mott insulators. The molecular quantum gas microscope will enable direct imaging and control of these phases and their excitations.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.