How fast can correlations spread in a quantum many-body system? In contrast to relativistic quantum field theory, no “speed limit” exists in non-relativistic quantum mechanics, allowing in principle for the propagation of information over arbitrary distances in arbitrary short times. However, one could naively expect that in real physical systems short-range interactions allow information to propagate only with a finite velocity. Here we report on the time-resolved detection of propagating correlations in an interacting quantum many-body system. By quenching a one-dimensional quantum gas in an optical lattice, we reveal how quasiparticle pairs transport correlations with a finite velocity across the system, resulting in an effective light cone for the quantum dynamics.
since Jan. 2011 Associate Professor at the University of Geneva (Switzerland) since Oct. 2008 Chargé de Recherche de 2eme class (CNRS) at CPHT, École Polytechnique (France) 2007-2010 Junior Research Chair of the network 'Triangle de la Physique' 2005-2007 Postdoc at University of Geneva working with T. Giamarchi 2005 PhD, RWTH Aachen, supervisors J. von Delft and U. Schollwöck Thesis: 'The adaptive time-dependent density-matrix renormalization group method: developement and applications' Awards: 2010 Prize for Physics of 'Akademie der Wissenschaften zu Goettingen' 2009 'Hertha Sponer Preis' of the German Physical Society (DPG)