CAREER: New Regimes of Coherent Nonequilibrium Dynamics in Quantum Many-Body Systems

About This Grant

NONTECHNICAL SUMMARY This CAREER award supports theoretical research and education in the broad field of nonequilibrium quantum dynamics with a view towards emerging quantum technologies. Quantum computing is a new mode of computation that harnesses the principles of quantum mechanics to store and process information. Rapid experimental progress is ushering in an era of useful near-term quantum computing platforms, with potential applications ranging from cryptography to drug design. Quantum computation relies on controlling the nonequilibrium dynamics of systems of many interacting quantum particles. Comprehending such dynamics thus plays a critical role in enabling future advances. Many-particle quantum systems tend to lose information about the state in which they were prepared. This tendency, known as quantum ergodicity, is detrimental to quantum computation, which hinges on the ability to preserve delicate quantum states and perform operations on them. The research component of this project will develop a theoretical understanding of a variety of mechanisms through which quantum ergodicity can be avoided. It will also consider how to realize these mechanisms on present-day quantum hardware with the long-term goal of expanding the toolkit for the study and manipulation of complex quantum systems. Quantum science and technology has been identified as a key national research priority. Sustaining leadership in this field requires nurturing a robust quantum workforce. To this end, the education component of this project includes developing an interdisciplinary quantum computing curriculum, whose success will grow the quantum talent pipeline. The principal investigator will also partner with institutional initiatives to engage in outreach around quantum physics topics. These activities will reach hundreds of precollege and college students and tap into popular excitement about quantum physics using hands-on activities and active learning approaches. TECHNICAL SUMMARY This CAREER award supports theoretical research and education in the broad field of nonequilibrium quantum dynamics with a view towards emerging quantum technologies. The research component addresses the foundational question of how quantum many-body systems can fail to relax to thermal equilibrium and maintain quantum coherence in the presence of strong interactions. Research activities are organized into three interrelated thrusts whose goals are: (1) Elucidate the role of emergent dynamical constraints in the far-from-equilibrium behavior of gauge theories and related quantum spin models. This question will be investigated using a combination of perturbation theory and numerical exact diagonalization to extract the timescales of relaxation processes in such systems. (2) Explore a general construction of quantum many-body scars, a dynamical regime where thermalization can be avoided by preparing the system in a special class of initial states. The construction hinges on the use of infinite-temperature thermofield-double states, which are of interest in both the high-energy physics and quantum information science communities. (3) Discover novel roadblocks to thermalization and decoherence intrinsic to quantum circuits, the natural setting for quantum computation. This project focuses on quantum circuits related to classical cellular automata, as well as circuits based on deterministic aperioidic sequences. All three topics are relevant to present-day experiments on platforms including cold atomic gases of bosons and fermions, arrays of Rydberg atoms in optical tweezers, and present day noisy intermediate-scale quantum hardware. Quantum science and technology has been identified as a key national research priority. Sustaining leadership in this field requires nurturing a robust quantum workforce. To this end, the education component of this project includes developing an interdisciplinary quantum computing curriculum, whose success will grow the quantum talent pipeline. The principal investigator will also partner with institutional initiatives to engage in outreach around quantum physics topics. These activities will reach hundreds of precollege and college students and tap into popular excitement about quantum physics using hands-on activities and active learning approaches. 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.