Mainz 2017 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 31: Poster: Quantum Optics and Photonics I
Q 31.10: Poster
Dienstag, 7. März 2017, 17:00–19:00, P OG1+2
Universal scaling and non-thermal fixed points in spin systems — •Stefanie Czischek1, Halil Cakir1, Markus Karl1, Michael Kastner2, Markus K. Oberthaler1, and Thomas Gasenzer1 — 1Kirchhoff-Institut für Physik, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany — 2Institute of Theoretical Physics, University of Stellenbosch, Stellenbosch 7600, South Africa
We study the dynamical build-up of correlations after sudden quenches in spin systems using the discrete truncated Wigner approximation. In particular, we consider quenches from large external fields into the vicinity of a quantum critical point within the paramagnetic phase. We calculate correlation lengths and study their time evolution at different distances from the critical point. For the transverse-field Ising chain, we find that the discrete truncated Wigner approximation is in good agreement with exact analytical and numerical results. Our exact results show that the correlation function takes the form given by a generalized Gibbs ensemble already after short times and small relative distances, which is also found in the discrete truncated Wigner approximation. The agreement of both results for quenches into the vicinity of the critical point suggests that the discrete truncated Wigner approximation may be used to determine the correlation dynamics after quenches for spin systems which are not exactly solvable, in one and higher dimensions.