Dresden 2020 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 48: Statistical Physics far from Thermal Equilibrium

DY 48.7: Talk

Thursday, March 19, 2020, 11:15–11:30, ZEU 147

Ageing and non-markovian effects in the exactly solved quantum O(n)-model — •Sascha Wald¹, Alessio Chiocchetta², Malte Henkel³, and Andrea Gambassi⁴ — ¹Max-Planck-Institut für Physik Komplexer Systeme, Nöthnitzer Straße 38, 01187, Dresden, Germany — ²Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany — ³Laboratoire de Physique et Chimie Théoriques (CNRS UMR 7019), Université de Lorraine Nancy, B.P. 70239, 54506 Vandoeuvre lès Nancy, France — ⁴SISSA - International School for Advanced Studies and INFN, via Bonomea 265, I-34136 Trieste, Italy

The effects of quantum noise on the non-equilibrium dynamics of many-body quantum systems, after a quantum quench, are analysed. Quantum noise, as opposed to the classical white noise, is inherently non-Markovian and the resulting dynamics is affected by memory effects, which lead to changes compared to Markovian white noises. In order to systematically analyse these effects, we study the quantum O(n)-model at large n, in contact with a bath at zero temperature. Starting from the quantum Langevin equation, the dynamical equations are explicitly solved. The universal properties of the dynamics, as given by the quantum noise and after a quantum quench, are analysed by studying the two-time correlation and response functions. Quantum coarsening and quantum ageing in these observables are highlighted and compared with their classical counterparts. In particular, the validity of the fluctuation-dissipation theorem after a quantum quench is studied in detail.