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DY: Fachverband Dynamik und Statistische Physik

DY 42: Focus: Many-Body Quantum Chaos

DY 42.6: Vortrag

Donnerstag, 4. April 2019, 11:15–11:30, H20

Scrambling and quantum butterfly effect in critical systems: instability vs. chaos — •Benjamin Geiger, Quirin Hummel, Juan Diego Urbina, and Klaus Richter — Universität Regensburg

The investigation of scrambling of information in interacting quantum systems has recently attracted a lot of attention as a manifestation of many-body quantum chaos. However, it has been demonstrated that certain integrable systems that are subject to quantum phase transitions allow for fast information scrambling if they are tuned close to their critical point [1]. To investigate the origin of this quasi-chaotic behavior we studied a momentum-truncated model of an attractive one-dimensional Bose gas using established semiclassical methods. We find that the quantum critical behavior has its origin in the appearance of a separatrix in the classcial phase space that renders the classical dynamics locally unstable. This leads to quasichaotic features the underlying quantum system, i.e., a fast growth of multiparticle entanglement and exponential growth of certain out-of-time ordered correlators, in counter-intuitive coexistence with asymptotic periodicity of the respective quantities.
[1] Dvali et al. Phys. Rev. D 88, 124041 (2013)