Non-equilibrium Critical Phenomena in Many-Body Quantum Systems

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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.