Regensburg 2019 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 4: Nonequilibrium Quantum Many-Body Systems 1 (joint session TT/DY)
TT 4.11: Talk
Monday, April 1, 2019, 12:15–12:30, H22
Sub-ballistic growth of Rényi entropies due to diffusion — •Tibor Rakovszky1, Frank Pollmann1, and Curt von Keyserlingk2 — 1Department of Physics, T42, Technische Universität München, James-Franck-Straße 1, D-85748 Garching, Germany — 2University of Birmingham, School of Physics & Astronomy, B15 2TT, UK
The growth of entanglement plays a fundamental role in the process of thermalization in closed quantum systems and has recently become amenable to experimental detection, through the measurement of so-called higher Rényi entropies. In this talk I will show that the behavior of such Rényi entropies can be qualitatively different from that of the theoretically more studied von Neumann entropy; in particular I will argue that the former grow sub-ballistically, as √t, in systems with diffusive transport. I provide evidence for this in both a U(1) symmetric random circuit model and in a non-integrable spin chain, where energy is the sole conserved quantity: I show how our results can be interpreted as a consequence of local quantum fluctuations in conserved densities.