Klaus Ritcher, from Regensburg University, will give a seminar entitled«Probing the Quantum Mechanics of Many-Body Chaos», as part of the seminar series of the Theory and Simulation of Materiales, organized by Álvaro Gómez-León and Sigmund Kohler.
Date: January 31st, 2020, 12:00 h.
Location: Events room. Instituto de Ciencia de Materiales de Madrid.
Abstract: The dynamics and spread of quantum information in complex many-body systems is presently attracting a lot of attention across various fields, ranging from cold atom physics via condensed quantum matter to high energy physics and quantum gravity. This includes questions of how a quantum system thermalizes and phenomena like many-body interference and localization, more generally non-classicality in many-particle quantum physics. Here concepts that are based on echoes, i.e. «rewinding» time, provide a powerful way to monitor complex quantum dynamics and its stability. Central to these developments are so-called out-of-time-order correlators (OTOCs) as sensitive probes for chaos and the temporal growth of complexity in interacting systems. We will address such phenomena for quantum critical and quantum chaotic systems using semiclassical path integral techniques based on interfering Feynman paths, thereby bridging the classical and quantum many-body world. These methods enable us to compute echoes and OTOCs including entanglement and correlation effects. Moreover, on the numerical side we devise a semiclassical method for Bose-Hubbard systems far-out-of equilibrium that allows us to calculate many-body quantum interference on time scales far beyond the famous Ehrenfest/scrambling time.