CAREER: Floquet Route to Non-Equilibrium Phases of Matter in Cavity QED

该职业奖支持非通常稳定平衡状态下光与物质相互作用状态的理论研究和教育。我们周围的世界是由量子力学描述的，然而量子力学现象在我们的日常生活中是缺席的。这种异常来自于构成日常物品的许多相互作用的原子的巨大复杂性，这些原子冲淡了量子效应，给出了经典世界。通过将电子和原子从这个复杂的环境中分离出来，实验学家们在越来越多的大型实用设备中实现量子效应方面取得了巨大的进步，这被称为第二次量子革命。这场革命将进一步推动人们在最基本的层面上理解量子物理学，这也是本次CAREER奖的首要目标。这项研究将集中在一类被称为多体腔量子电动力学（QED）的系统上，它可以获得光的量子特性，并洞察光与物质之间的相互作用。量子力学告诉我们，光以称为光子的单个单位出现，但传统的激光器包含太多的光子，因此不可能从每个光子中看到量子效应。腔QED的工作原理是将光限制在两个几乎完美的镜子之间。然后，一个人准备的状态不是数百万或数十亿的光子在腔中，而是一个或两个。当光子数低到可以看到单个光子时，光子的行为是量子力学的。多体腔QED由这些光子与具有量子力学行为的原子相互作用组成。该项目将研究这些系统在被踢出平衡状态时的反应，由于光和物质之间的量子力学推拉，预计将给出定性的新特征。这些相互作用将进一步在各种量子技术中提供应用，例如下一代激光器和高精度传感器。这项研究将通过一个围绕设计虚拟现实（VR）模块的教育项目进行补充，该模块允许用户与氢原子等简单的量子力学系统进行交互。虚拟现实模块通过将用户缩小到氢原子的大小，使他们能够直接与量子力学世界互动。从教育的角度来看，量子VR模块将提供一种新的途径来学习量子力学的基本规则，而不需要数学开销。随着量子力学日益成为科学技术不可或缺的一部分，这将创造与培养下一代科学家和工程师相关的理解和兴奋。本职业奖支持光与物质相互作用的非平衡态的理论研究和教育。时间周期或Floquet驱动是工程量子系统最强大的工具之一。传统上，使用强高频驱动来修改有效哈密顿量，使中性原子中的强有效磁场等人工结构得以实现。最近，人们发现了新的物质相，它们利用了弗洛凯驱动的基本非平衡性质。Floquet时间晶体等例子在他们的理论发现后很快就被实现了，为新的非平衡路径打开了通往对称破断的大门。在实践中，Floquet驱动通常是通过微波或光子来实现的。将这些光子限制在一个腔内，它们也可以被视为量子自由度，这是一种被称为多体腔量子电动力学（QED）的范式。半经典的Floquet极限是在空腔光子占用较大时获得的，但空腔提供了通过减少光子数达到量子极限的有趣可能性，从而进入强耦合量子光和物质的不同状态。本研究将研究物质非平衡Floquet相的多体腔QED极限。这样做自然会导致具有异常行为的物质的新非平衡状态，这可能被认为是由本地相互作用和由腔介导的全局相互作用之间的竞争引起的。该研究将涉及三个广泛的方向：(1)理解热化和多体局域化之间的竞争，(2)证明对称破缺状态，如空腔存在下的时间晶体，以及(3)对耦合到一个或多个空腔的物质拓扑状态进行分类，包括量子化光子泵。这项工作将在多体腔QED和Floquet物理学这两个活跃但大多独立的领域之间架起一座桥梁，为研究位于通常考虑的极限之间的物质的新相提供了一条途径。研究小组将扩展物质非平衡相的分类，其中由短期和长期相互作用相互作用引起的异常状态仍然特别具有挑战性。实验实现将探索氮空位中心、超导电路、超冷原子和捕获离子。由此产生的强耦合光与物质的纠缠态将与量子信息的基础科学和量子计量的应用相关。这项研究将通过设计一个虚拟现实（VR）模块来补充，允许用户与简单的量子力学系统进行交互。量子虚拟现实将阐述量子力学的一些关键方面，如电子的波动性质、量子测量和辐射衰变，这些对许多学习者来说都是难以捉摸的。这对于公共科学和技术应用都是至关重要的，因为量子技术变得越来越相关，降低了科学家、工程师和公众的进入门槛。来自用户的反馈将成为未来在更广泛的量子系统中开发可视化方法的种子。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。

NONTECHNICAL SUMMARYThis CAREER award supports theoretical research and education into states of interacting light and matter that are not in usual steady states of equilibrium. The world around us is described by quantum mechanics, yet quantum mechanical phenomena are absent from our day-to-day life. This anomaly comes from the enormous complexity of the many interacting atoms that make up everyday objects, which wash out quantum effects to give the classical world. By isolating electrons and atoms from this complex environment, experimentalists have made enormous strides towards realizing quantum effects in increasing large and practical devices, which has become known as the second quantum revolution. This revolution will further the need for understanding quantum physics at its most fundamental level, which is the overarching goal of this CAREER award. The research will focus on a class of systems known as many-body cavity quantum electrodynamics (QED), which gives access to quantum properties of light and insight into the interaction between light and matter. Quantum mechanics tells us that light comes in individual units called photons, but conventional lasers contain so many photons that seeing quantum effects from each one is impossible. Cavity QED works by confining the light between two nearly perfect mirrors. One then prepares states where there are not millions or billions of photons in the cavity, but rather one or two. When the photon number is so low that individual photons can be seen, the photons behave quantum mechanically. Many-body cavity QED consists of these photons interacting with atoms that behave quantum mechanically as well. This project will study how these systems respond when they are kicked out of equilibrium, which is anticipated to give qualitatively new features due to the quantum mechanical push and pull between the light and the matter. These interactions should further provide applications down the road in a variety of quantum technologies, such as next-generation lasers and high-precision sensors.The research will be complemented by an educational program built around designing a virtual reality (VR) module allowing users to interact with simple quantum mechanical systems such as the hydrogen atom. By virtually shrinking the user to the size of the hydrogen atom, the VR module will enable them to interact with the quantum mechanical world directly. From an educational standpoint, the quantum VR module will provide a new route to learn about the fundamental rules of quantum mechanics without the mathematical overhead. This will create understanding and excitement which is relevant to training next-generation scientists and engineers, as quantum mechanics becomes an increasingly indispensable part of science and technology.TECHNICAL SUMMARYThis CAREER award supports theoretical research and education into nonequilibrium states of interacting light and matter. Time-periodic, or Floquet, driving is one of the most powerful tools for engineering quantum systems. Traditionally, a strong high frequency drive is used to modify the effective Hamiltonian, enabling the realization of artificial structures such as strong effective magnetic fields in neutral atoms. Recently, new phases of matter have been discovered that exploit the fundamentally nonequilibrium nature of the Floquet drive. Examples such as the Floquet time crystal were quickly realized after their theoretical discovery, opening the door for novel nonequilibrium routes to symmetry breaking.In practice, the Floquet drive is often done by microwave or optical photons. Confining these photons to a cavity, they may also be treated as quantum degrees of freedom, a paradigm known as many-body cavity quantum electrodynamics (QED). The semiclassical Floquet limit is obtained when the cavity photon occupation is large, but cavities afford the intriguing possibility of going to quantum limit by decreasing the photon number, thus accessing a different regime of strongly coupled quantum light and matter.This research will study the many-body cavity QED limit of nonequilibrium Floquet phases of matter. Doing so naturally leads to new nonequilibrium states of matter with anomalous behavior, which may be thought of as arising from competition between native local interactions and global interactions mediated by the cavity. The research will involve three broad directions: (1) understanding the competition between thermalization and many-body localization in a cavity, (2) demonstrating symmetry breaking states such as time crystals in the presence of the cavity, and (3) classifying topological states of matter coupled to one or more cavities, including quantized photon pumps.This work will bridge the active but mostly independent fields of many-body cavity QED and Floquet physics, providing a pathway to new phases of matter that lie between the limits that are often considered. The research team will extend the classification of nonequilibrium phases of matter, where anomalous states induced by the interplay of short- and long-range interactions remain particularly challenging. Experimental realizations will be explored in nitrogen vacancy centers, superconducting circuits, ultracold atoms, and trapped ions. The resulting entangled states of strongly coupled light and matter will have relevance to the fundamental science of quantum information and applications in quantum metrology.This research will be complemented by designing a virtual reality (VR) module allowing users to interact with simple quantum mechanical systems. The quantum VR will illustrate some key aspects of quantum mechanics, such as the wave nature of electrons, quantum measurements, and radiative decay, which have proved elusive to many learners. This is vital for both public science and technological applications as quantum technologies become increasingly relevant, lowering the barrier to entry for scientists, engineers, and members of the public. Feedback from users will serve as a seed for future development of visualization methods in a broader range of quantum systems.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.