CAREER: Non-Equilibrium Quantum Physics in Solid-State Spin Chains

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Non-technical abstract: Statistical mechanics and thermodynamics underlie nearly all fields of science, including biology, chemistry, and physics. This project studies phenomena in objects that do not reach thermal equilibrium with their surroundings, such as an imaginary coffee cup that stays hot forever. The study of these systems is important and may have diverse applications in fields like high-temperature superconductivity and quantum computing. A significant component of this project involves education and outreach efforts to address the “leaky pipeline,” which prevents women and minorities from full involvement in scientific research. The PI is developing interactive, week-long courses in experimental physics for middle- and high-school students during the summer and workshops during the school year designed to ignite a passion for experimental research in the next generation of scientists. The PI is also developing a quantum technology course for undergraduates and is mentoring undergraduate and graduate students in state-of-the-art quantum nanotechnology.Technical abstract: The research objective of this project is to investigate non-equilibrium quantum physics in quantum-dot spin chains. The fundamental postulate of statistical mechanics is that a physical system will sample every possible configuration available to it with equal probability, leading to thermodynamic equilibrium. In a bizarre phenomenon called many-body localization, this assumption breaks down, and disorder in the system prevents thermalization, even in the presence of inter-particle interactions. Another unusual hallmark of localized states is the appearance of time-crystal phases. Just as conventional crystals spontaneously break spatial translation symmetry, time crystals can break time-translation symmetry. In time crystals, a subharmonic response of the system to a periodic drive persists indefinitely. Many-body localization and time-crystals challenge our understanding of statistical mechanics and thermodynamics and will prove valuable resources for quantum information processing. Evidence of localization and time-crystals in solid-state materials remains elusive. The specific objectives of this project involve using spin chains in gate-defined quantum-dot arrays to explore many-body localization and time-crystals in condensed matter systems and uncover their phase diagrams.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.