Freiburg 2019 – scientific programme

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FM: Fall Meeting

FM 35: Entanglement: Many-Body Dynamics I

FM 35.6: Talk

Tuesday, September 24, 2019, 15:15–15:30, 2004

Reversible quantum information spreading in many-body systems near criticality — •Benjamin Geiger, Quirin Hummel, Juan-Diego Urbina, and Klaus Richter — Institut für Theoretische Physik, Universität Regensburg

Quantum chaotic interacting N-particle systems are assumed to show fast and irreversible spreading of quantum information on short (Ehrenfest) time scales ∼ logN . Here we show that, near criticality, certain many-body systems exhibit fast initial scrambling, followed subsequently by oscillatory behavior between reentrant localization and delocalization of information in Hilbert space. Specifically, we consider quantum critical bosonic systems with attractive contact interaction that exhibit locally unstable dynamics in the corresponding many-body phase space of the large-N limit. Semiclassical quantization of the latter accounts for many-body correlations in excellent agreement with simulations. Most notably, it predicts an asymptotically constant local level spacing ∼ 1/τ, again given by τ∼logN, if the quantum phase transition is driven by a single (slow) degree of freedom. This unique timescale governs the long-time behavior of out-of-time-order correlators and entanglement entropies that, in certain scenarios, feature quasi-periodic recurrences indicating reversibility.