Nonequilibrium Quantum Mechanics of Strongly Correlated Systems

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NON-TECHNICAL SUMMARY:The award supports research and education on the dynamics of complex systems where both quantum mechanics as well as strong interactions between many particles are important. This challenging regime has many open questions of relevance for a new generation of experiments and quantum devices. The PI and her research team will study how such systems evolve in time, whether their collective temporal behavior can show some system-independent universal properties, and under what conditions traces of their initial state disappear completely. The projects will bring together concepts from diverse fields of physics.The award has a strong educational component that involves the active participation of graduate and undergraduate students, and a postdoctoral research scientist. The results of the projects will be presented at workshops and conferences, and will be incorporated in a review article in a journal widely read by the community. The project will lead to the development of new theoretical approaches to study the dynamics of complex systems, and will address fundamental questions of relevance to quantum information and quantum computing. The PI will also participate in outreach activities that are part of a continuing partnership between the NYU physics department and local schools.TECHNICAL SUMMARY:The award supports research and education on nonequilibrium phenomena in strongly correlated quantum systems. The focus will be to study quench dynamics in closed and open quantum systems with applications to cold-atomic gases, ultra-fast pump-probe spectroscopy of solid-state systems, and light-matter coupled systems.The project has several components:a) The research team will build on their recent work where universal aging behavior was found after a quantum quench to the critical point of an isolated bosonic O(N) model, and explore similar universality in other kinds of bosonic and fermionic models. Large-N and dimensional expansions methods will be used to study the time-evolution, and to identify scaling behavior at intermediate times, as well as light-cone dynamics.b) The research team will also study the dynamics of entanglement entropy and entanglement spectrum after a quantum quench. This study will be carried out for quenches to the critical point, as well as for interacting one-dimensional systems with strong disorder.c) The research team has access to some exact results for the quench dynamics coming from the large-N limit of interacting field theories. These exact results will be used as a benchmark for developing time-dependent variational methods based on tensor network states.The goal of the projects will be to obtain general results not only on universal dynamics after a quantum quench, but also on the dynamics of entanglement entropy and entanglement spectra. Thus, results will be obtained on how fast information travels after a quantum quench, and how this depends on how excited the system is, its dimensionality, proximity to a critical point, range of interactions, and how ergodic the system is. The project will also result in the development of new methods to study nonequilibrium quantum systems.The award has a strong educational component that involves the active participation of graduate, undergraduate students, and a postdoctoral research scientist. The results of the projects will be presented at workshops and conferences, and will be incorporated in a review article on quantum quenches. The award will lead to the development of new theoretical approaches to study nonequilibrium phenomena. Moreover the PI's study of entanglement dynamics will address fundamental questions of relevance to quantum information and quantum computing. In addition, the PI will participate in outreach activities that are part of a continuing partnership between the NYU physics department and local schools.