Non-equilibrium Critical Phenomena in Many-Body Quantum Systems

该奖项支持对非平衡态物质量子特性的研究和教育。量子力学支配着微观世界，在微观世界中，原子和电子的行为方式与直觉不符。它还描述了许多粒子形成集体量子态的物质的宏观相。然而，量子特性在高温下通常是模糊的，并且远离固定的平衡状态，这种情况发生在实际系统中，实际上几乎从未与外部扰动隔离。另一方面，量子力学的真正应用需要在可以操纵远离平衡的大型系统中利用这些特性。该项目的目标是确定“量子”在非常低的温度下远离静止状态的情况。PI将识别许多粒子远离平衡的集体行为，并将识别它们的行为是普遍的程度，即独立于单个系统的特殊性。拟议的研究将有助于确定控制量子系统并保护其量子特征远离平衡的新途径，这一方向可能对量子存储器和量子计算应用有用。为了吸引更广泛的公众，PI正在与密歇根州的物理学家和密歇根州立大学博物馆艺术实验室的当地艺术家合作，计划举办一系列名为“薛定谔的猫在城里！”的研讨会。这些工作坊将在互动的环境中吸引公众，也将涉及基于物理概念的艺术创作。最近的实验进展为非平衡量子现象的新时代打开了一扇窗。它们也对我们的描述能力提出了巨大的挑战，因为大多数熟悉的物理工具都是专门为平衡条件下的系统设计的。虽然非平衡量子多体系统因其量子特性而具有新的令人兴奋的可能性，但它们往往最终表现出有效的经典行为。这极大地限制了量子域的范围，实际上将其限制在低温下的无扰动平台上。对于在相变附近出现的临界行为，这个问题尤其尖锐：非平衡量子系统没有达到，或者贡献远远超过，理解经典系统中临界现象的伟大胜利。该奖项支持一项综合研究、教育和推广计划，重点关注远离平衡的宏观量子系统的动力学。PI旨在通过识别真正的非平衡量子行为出现的情况来显著拓宽现有的视角。这将在系统参数突然变化后的孤立量子系统以及连续驱动的开放量子系统的长时间和短时间动力学的四种设置中实现。目标是发现新的动力学和量子普适性类，在平衡中没有对应的。本提案的一个具体目标是在孤立和开放量子系统的不同设置中开发一个统一的框架。提出的研究将有助于确定控制量子系统和保护其量子特征远离平衡的新途径，这一方向可能对存储和处理量子信息的应用有用。为了吸引更广泛的公众，PI正在与密歇根州的物理学家和密歇根州立大学博物馆艺术实验室的当地艺术家合作，计划举办一系列名为“薛定谔的猫在城里！”的研讨会。这些工作坊将在互动的环境中吸引公众，也将涉及基于物理概念的艺术创作。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 award supports research and education towards understanding the quantum properties of matter away from equilibrium. Quantum mechanics governs the microscopic world, where atoms and electrons behave in ways that defy intuition. It also describes macroscopic phases of matter where many particles form a collective quantum state. However, quantum properties are generally obscured at high temperatures and away from a stationary equilibrium state, a situation that occurs in real systems that are in practice almost never isolated from external perturbations. On the other hand, true applications of quantum mechanics require harnessing such properties in large systems that can be manipulated away from equilibrium.The goal of the project is to identify situations where "quantumness" persists far from a stationary state at very low temperatures. The PI will identify the collective behavior of many particles away from equilibrium and will identify the degree to which their behavior is universal, i.e. independent of the individual system's particularities.The proposed research will help identify new avenues to control quantum systems and to protect their quantum features far from equilibrium, a direction that could be useful for quantum memory and quantum computing applications. To engage the broader public, the PI is planning a series of workshops called "Schroedinger's Cat is in Town!" in partnership with Michigan-based physicists and local artists from the Michigan State University Museum Art Lab. These workshops will engage the public in an interactive setting and will also involve creating art based on physics concepts.TECHNICAL SUMMARYRecent experimental advances have opened a window to a new era of nonequilibrium quantum phenomena. They have also posed a great challenge to our descriptive capabilities as most of the familiar tools in physics are specifically designed for systems under equilibrium conditions. While nonequilibrium quantum many-body systems hold promise for new and exciting possibilities stemming from their quantum nature, they often end up exhibiting an effective classical behavior. This significantly limits the range of the quantum domain and in fact restricts it to unperturbed platforms at low temperatures. The issue is especially acute for critical behavior emerging near phase transitions: nonequilibrium quantum systems have not matched, or contributed much beyond, the grand triumph of understanding critical phenomena in classical systems.This award supports an integrated research, education, and outreach program focused on the dynamics of macroscopic quantum systems far from equilibrium. The PI aims to significantly broaden the existing perspective by identifying situations where a genuinely nonequilibrium, quantum behavior emerges. This will be achieved in four settings of long- and short-time dynamics in both isolated quantum systems after a sudden change of system parameters, as well as in open quantum systems that are continuously driven. The goal is to discover novel dynamical and quantum universality classes with no counterpart in equilibrium. A specific aim of this proposal is to develop a unified framework in the different settings of isolated and open quantum systems.The proposed research will help identify new avenues to control quantum systems and to protect their quantum features far from equilibrium, a direction that could be useful for applications in storaging and processing of quantum information. To engage the broader public, the PI is planning a series of workshops called "Schroedinger's Cat is in Town!" in partnership with Michigan-based physicists and local artists from the Michigan State University Museum Art Lab. These workshops will engage the public in an interactive setting and will also involve creating art based on physics concepts.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.