Center for Ultracold Atoms

理解和控制量子世界是物理科学面临的巨大挑战之一。迎接这些挑战可以为设计新形式的物质开辟道路，并可能为信息处理开辟新的途径。在这个探索中，强相互作用的系统既是当前最大的科学挑战，也是最高的潜在回报。超冷原子为追求这一目标提供了一种新的媒介，因为它们可以以前所未有的精度进行控制和操纵，并且可以以惊人的清晰度进行观察。这项工作的智力价值在于探索自然和人工材料的工作原理，理解复杂的量子系统，探索工程量子系统的基本物理和潜在应用。到目前为止，许多强相关系统的性质，它们的动力学行为，以及量子控制对复杂量子系统的基本和实际限制还没有得到很好的理解。此外，尽管受控量子系统有着巨大的前景，但只有很少的实际应用是已知的。该中心的工作将试图揭开这些谜团。这可能会导致物质的新量子相的产生，对多体量子系统的更好理解和极大地改进控制，以及这些系统的新应用。在这些考虑的推动下，超冷原子中心在两个主题的指导下开展研究：多体系统和强相关态；和量子相干控制的少体系统。这些科学主题是互补的。特别是，在第一个主题中，强相关系统可以通过设计稀释超冷气体大云的相互作用和运动来实现。这种自上而下的量子系统方法在CUA中与第二个主题相匹配，其中自下而上的方法使用单个粒子的相干量子控制；可控制的量子集可以连接起来，以建立越来越复杂的量子系统。在CUA的第三阶段，我们仍然专注于这两个关键的科学主题，但在我们的研究范围内增加了一个主要的内容，包括新的类原子和混合量子系统。具体来说，我们使用和研究类原子固体杂质，纳米级光子和等离子体腔和波导，以及超导和纳米机械谐振器，以便在一个新的，以前无法达到的水平上获得量子控制和操纵。这些系统与冷原子有一个共同的特性，即它们可以用原子物理学的概念和工具精确地制备和操纵。我们增加这些新方法的主要动机是将AMO技术扩展到精确的量子态控制，以实现“真实”原子无法实现的全新参数体系。同时，我们将利用这些系统探索新的科学方向和潜在的应用。在主题1中，多体系统领域，项目包括使用量子显微镜或单原子杂质对强相关态的微观控制和探测，远离平衡的多体动力学研究，以及具有强相关性的新系统的实现，特别是量子磁性和自旋晶格系统的研究。在主题2中，少体系统领域，我们继续我们在强耦合原子-光子系统的量子态控制方面的工作，并通过将焦点转移到类原子和量子混合系统来增加对CUA的主要扩展。最近的开创性工作（主要来自CUA）表明，冷原子科学的精确方法现在可以应用于某些固态量子系统。这允许创造长寿命的相干叠加态，并在以前无法达到的长度和能量尺度上产生量子纠缠（例如，在稀原子气体和固体物质之间）。此外，新的强相互作用的AMO系统，如里德堡原子，极性分子和离子晶体将被探索，有时作为一个混合系统的一部分。这些新系统为访问新的参数制度和设备集成的新方法提供了途径。一个主要的新焦点将是混合系统，在混合系统中，不同的量子平台是耦合的（例如，固态自旋和光子，分子和超导体，孤立的原子和纳米级波导）。这些途径可能会导致可扩展量子系统的重大进展，以及新应用程序的开发。在这项工作的过程中，AMO物理学和纳米科学之间的一个新的科学接口将被探索。这项工作的广泛影响跨越了广泛的领域，包括材料科学、计量学、传感、通信和计算、化学物理、生物科学和能源研究。一些可能性包括：晶格限制原子或极性分子的量子模拟可能会揭示诸如高tc超导体之类的材料，并最终导致具有定制设计特性的新材料的开发。对光与物质之间的量子接口的研究可能使我们能够开发出用于远距离量子通信和密码术的实用系统。相关原子态的鲁棒生成，例如与光学时钟跃迁兼容的系统中的自旋压缩态，可以潜在地将时钟性能扩展到前所未有的水平。量子控制的类原子和混合系统，如金刚石中的NV中心，可能会在纳米尺度上产生独特的生物系统磁场探针。在低光水平下量子非线性光学的研究可以为节能的全光开关和计算提供新的途径。在纳米尺度上理解和控制光与物质的相互作用可能最终导致能量收集和转换的新方法。除了作为一个研究中心，该中心还将利用现有的和新的努力，继续把重点放在教育和推广上。一系列得到良好支持的活动将继续对K-12、本科和研究生阶段（包括在中央大学核心机构内外）以及更广泛的研究界和公众产生影响。成功的持续活动包括面向未来高中教师的TOPS项目和原子物理学暑期强化课程（向全世界的学生和其他研究人员开放）。我们在第三阶段开始的一项新活动的一个例子是制作解释性视频，描述针对学生和公众的CUA研究。我们还启动了一些项目，邀请有兴趣的少数族裔服务机构的本科生到美国大学进行暑期研究，并启动了一些项目，让高中生接触到美国大学的研究。CUA的一个标志是灵活地增加新的外展和教育项目，因为他们的构想，我们将继续这一传统。中国科学院的一个主要影响是对研究生和博士后的教育。大批年轻的中大研究人员已晋升到学术界和工业界的领导地位。通过赞助研讨会、两年一次的原子物理暑期学校、原子量子气体虚拟期刊及其访客计划，美国量子力学协会与科学界分享了它的愿景和专业知识。

Understanding and controlling the quantum world are among the great challenges of physical science. Meeting these challenges can open the way to the design of new forms of matter and possibly new paths to information processing. In this quest, strongly interacting systems present both the current greatest scientific challenges and also the highest potential rewards. Ultracold atoms provide a new medium for pursuing this quest because they can be controlled and manipulated with a precision never previously possible, and observed with a clarity that can be breathtaking. The intellectual merit of this work is the quest to discover how natural and artificial materials work, to understand complex quantum systems, and to explore the basic physics and potential applications of engineered quantum systems. As of now, the nature of many strongly correlated systems, their dynamical behavior, and the fundamental and practical limits of quantum control over complex quantum systems are not well understood. Furthermore, only very few practical applications of controlled quantum systems are known, despite the great promise they hold. The work of the Center will attempt to uncover these mysteries. This may lead to the creation of new quantum phases of matter, to a better understanding and greatly improved control over many-body quantum systems, and to new applications of such systems.Motivated by these considerations, the Center for Ultracold Atoms carries out research guided by the two themes of: Many-body systems and strongly correlated states; and Quantum coherent control of few-body systems. These scientific themes are complementary. In particular, within the first theme, strongly correlated systems can be realized by engineering the interactions and motion of large clouds of dilute ultracold gases. This kind of top-down approach to quantum systems is matched in the CUA with the second theme, where a bottom-up approach uses coherent quantum control of individual particles; controllable sets of quanta can be connected to build up increasingly more complex quantum systems. In what is now the third phase of the CUA, we retain focus on these two key scientific themes, but with a major addition to our spectrum of research to include new atom-like and hybrid quantum systems. Specifically, we use and study atom-like solid-state impurities, nanoscale photonic and plasmonic cavities and waveguides, as well as superconducting and nano-mechanical resonators in order to obtain quantum control and manipulation at a new, previously inaccessible level. These systems share with cold atoms the property that they can be precisely prepared and manipulated using the concepts and tools of atomic physics. Our key motivation for adding these new approaches is to extend the AMO techniques for precise quantum state control to completely new parameter regimes not accessible with "real" atoms. At the same time we will use these systems to explore new scientific directions and potential applications.Within theme 1, the area of many-body systems, projects include microscopic control and probing of strongly correlated states using a quantum microscope or single atom impurities, the study of many-body dynamics far away from equilibrium, and the realization of new systems with strong correlations, in particular the study of quantum magnetism and spin-lattice systems simulated using polar molecules. Within theme 2, the area of few-body systems, we continue our work on quantum state control of strongly coupled atom-photon systems, as well as add a major extension to the CUA by shifting focus towards atom-like and quantum hybrid systems. Recent pioneering work (with major contributions from the CUA) has shown that the precise methods of cold atom science can now be applied to certain solid-state quantum systems. This allows for the creation of long-lived coherent superposition states and the generation of quantum entanglements at previously inaccessible length and energy scales (e.g. between those of dilute atomic gases and solid matter). In addition, novel strongly interacting AMO systems such as Rydberg atoms, polar molecules and ion crystals will be explored, sometimes as part of a hybrid system. These new systems offer avenues to access new parameter regimes and new approaches to device integration. A major new focus will be on hybrid systems, where disparate quantum platforms are coupled (e.g. solid-state spins and photons, molecules and superconductors, isolated atoms and nanoscale waveguides). Such avenues may result in major advances towards scalable quantum systems, and in the development of new classes of applications. In the course of this work a new scientific interface between AMO physics and nanoscience will be explored. The broader impacts of this work span a wide range of areas, including materials science, metrology, sensing, communication and computation, chemical physics, biological science and energy research. Some possibilities include: The quantum simulation possible with lattice confined atoms or polar molecules could shed light on materials such as high-Tc superconductors, and eventually result in development of new materials with custom-designed properties. Work on quantum interfaces between light and matter may allow us to develop practical systems for long-distance quantum communication and cryptography. Robust generation of correlated atomic states, such as spin-squeezed states in systems compatible with optical clock transitions, can potentially extend clock performance to unprecedented levels. Quantum controlled atom-like and hybrid systems such as NV centers in diamond may yield unique probes for magnetic fields in biological systems at the nanoscale. Work on quantum nonlinear optics at low light levels could result in new approaches for energy-efficient all-optical switching and computation. Understanding and control of light-matter interaction at nanoscales could eventually result in novel approaches for energy harvesting and conversion.As well as being a research center, the CUA will continue its focus on education and outreach, using both existing and new efforts. A full spectrum of well-supported activities will continue to make an impact at the K-12, undergraduate and graduate levels (both inside and outside the CUA core institutions), as well as the broader research community and the public. Examples of successful continuing activities include the TOPS program for future high school teachers and the intensive summer course in atomic physics (open to students and other researchers worldwide). An example of a new activity we begin in phase 3 is the production of explanatory videos that describe CUA research, aimed at students and the public. We are also initiating programs to bring to the CUA, for summer research, interested undergraduates from minority serving institutions and programs to expose high-school students to CUA research. A hallmark of the CUA has been the flexible addition of new outreach and education programs as they are conceived, and we will continue this tradition. A major impact of the CUA is through its education of graduate students and postdocs. A large number of young CUA researchers have advanced to leadership positions in academia and industry. Through sponsorship of workshops, the biannual Atomic Physics summer school, the Virtual Journal of Atomic Quantum Gases, and its visitors program, the CUA shares its vision and expertise with the scientific community.