QII-TAQS: Quantum Control of Ultracold Atoms in Optical Lattices for Inertial Sensing for Space Applications

要知道自己在地球上的位置，只需在智能手机上打开一个地图应用程序。这得益于全球定位卫星（GPS）基础设施的可用性。然而，知道航天器在星际或深空中的位置是一个相当困难的挑战。目前，航天器的位置信息主要是通过在飞行器和地球上的无线电发射机之间发送的无线电信号获得的，有时也通过从飞行器向附近的物体（如行星或其他大型物体）发送的无线电信号获得。这种辐射位置传感成本高，速度慢。这个研究项目是量子物理学家、航空航天工程师和控制系统工程师之间的合作，重点是开发新的量子技术，利用原子作为非常精确的惯性传感器来测量航天器的加速度和旋转。具体来说，新的量子技术使用的是被激光束限制和操纵的原子，形成光学晶格。原子惯性传感器与高精度的原子钟相结合，作为导航系统的核心，不需要任何外部参考，如无线电信号或图像来提供位置信息。因为原子有质量，它们直接受到导致车辆加速或旋转的力的影响。利用量子叠加，研究人员利用原子的量子波特性来非常精确地测量这些力。在行星际空间中，即使是非常微小的小行星撞击的力量，随着时间的推移，也会大大改变航天器的轨道：目前没有任何技术精确到足以追踪如此微小的力量。要完全知道一艘宇宙飞船经过一个大质量物体附近时的位置，就必须考虑到引力的影响。这是通过测量航天器内不同位置的原子同时受到的加速度来实现的。重力梯度法还提供了监测地球健康状况的重要手段：例如，地球重力场随着极地冰块的移动而变化。因此，这项新量子技术的研究可能会改进地球监测工具，并极大地促进太空旅行。本研究利用基础科学和工程技术，推进基于光学原子晶格的惯性传感技术，用于测量加速度、旋转和重力，统称为惯性传感。人们普遍认为，量子技术在国家安全、科学和商业领域的应用中具有颠覆性潜力。例如，在gps被拒绝的环境中导航，目前是武装部队非常关注的问题。在某些情况下，与传统技术（如环形激光和光纤陀螺仪）相比，基于原子干涉测量的惯性传感器在性能上提供了数量级的改进。的确，实验室系统已经展现出突破性的表现。这项工作设想的应用程序具有重要的尺寸限制，并且环境有时是高度动态的。为了解决这些实际问题，研究重点是基于光学原子晶格的先进惯性传感器。利用干涉对激光束将激光冷却的原子限制在周期性结构中产生光学晶格。光学晶格可以用许多g（地球表面的重力加速度）的加速度来限制原子。通过调制形成光学晶格的激光束来操纵超冷原子量子态的新方法，将为一种全新的量子原子干涉惯性传感器提供一条途径，这种传感器能够在动态环境中工作，同时保持小的外形因素。关键的创新将从对晶格中原子的多体物理的深刻理解与反馈和控制方法的发展相结合，这些方法可用于优化定制惯性传感器对给定传感场景的响应。这项工作的领域侧重于空间应用，如地球重力监测和深空卫星导航。本研究的主要目的是将光学原子晶格传感器从纯粹的科学研究发展到工程研究。从战略上讲，这项工作代表了惯性传感量子技术路线图的第一个里程碑。这项工作的高级目标是建立一个传感器原型设施，作为开发和测试传感器概念的平台，该设施将提供给未来几代学生和工业界。随着时间的推移，其他关键的经典工程学科将被引入到一个协作的努力中，以推进系统层面的整体技术水平。该奖项反映了美国国家科学基金会的法定使命，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。

Knowing one's location on Earth is simply a matter of opening a Maps application on a smartphone. This is made possible by the availability of the Global Positioning Satellite (GPS) infrastructure. Knowing a spacecraft's position in interplanetary or deep space, however, is a considerably more difficult challenge. Spacecraft position information is presently obtained primarily using radio signals sent between the vehicle and radio transmitters on Earth, and sometimes by radio signals sent from the craft to a nearby object, such as a planet or other large object. Such radiometric position sensing is costly and slow. This research project, a collaboration between quantum physicists, aerospace engineers, and control systems engineers, centers on the development of new quantum technology that uses atoms as very precise inertial sensors to measure accelerations and rotations of a spacecraft. Specifically, the new quantum technology uses atoms that are confined and manipulated by laser beams forming an optical lattice. Combined with a highly-accurate atomic clock, the atomic inertial sensor serves as the core of a navigation system that does not need any external references such as radio signals or images to provide position information. Because atoms have mass, they are directly affected by forces that cause a vehicle to accelerate and or rotate. Using quantum superposition, the researchers take advantage of the quantum wave properties of atoms to measure these forces very precisely. In interplanetary space, even the forces of impact of very tiny asteroids can add up to change the trajectory of a spacecraft significantly over time: no current technology is precise enough to track such small forces. To know completely the position of a spacecraft that passes near a massive body one must account for the effects of gravitational forces. This is done by measuring acceleration forces on atoms at the same time at different places within the spacecraft. Gravity gradiometry also provides a significant means of monitoring the health of the Earth: for example, the Earth's gravity field changes with shifts in the polar ice masses. This research in new quantum technology is thus likely to lead to improved tools for Earth monitoring as well as greatly facilitating space travel. This research employs basic science and engineering toward the advancement of optical atomic lattice-based inertial sensing for measuring acceleration, rotation, and gravity, collectively referred to as inertial sensing. Quantum technology is widely acknowledged to hold disruptive potential in applications of interest to national security, science, and commercial industry. Navigation in a GPS-denied environment, for example, is currently of great concern for the armed services. In some cases, inertial sensors based on atom interferometry offer orders-of-magnitude improvement in performance compared to classical technologies such as ring laser and fiber gyroscopes. Indeed, laboratory systems have exhibited groundbreaking performance. This work envisions applications where significant size constraints are at play and the environment is sometimes highly dynamic. To address such practical considerations, the investigation focuses on advanced inertial sensors based on optical atomic lattices. An optical lattice is produced using interfering pairs of laser beams to confine laser-cooled atoms in periodic structures. Optical lattices can confine atoms with accelerations of many g (the gravitational acceleration at the Earth's surface). New methods for manipulating the quantum state of ultracold atoms by modulating the laser beams forming the optical lattice will provide a pathway to an entirely new class of quantum-enabled atom interferometric inertial sensors capable of operating in a dynamic environment while maintaining a small form factor. Key innovations will evolve from combining a deep understanding of the many-body physics of atoms in lattices with the development of feedback-and-control methods that can be used to optimally tailor the inertial sensor response to a given sensing scenario. The domain of this work focuses on space applications such as monitoring of the Earth's gravity and navigation of satellites in deep space. A primary purpose of this research is the evolution of optical atomic lattice sensors from a purely scientific endeavor to an engineering one. Strategically, this work represents the first milestone of an inertial sensing quantum technology roadmap. The high-level goal of this effort is to establish a sensor prototype facility that will be made available to future generations of students and to industry as a platform on which to develop and test sensor concepts. Over time, other critical classical engineering disciplines will be brought into a collaborative effort to advance the overall state-of-the-art at the system level.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.