Corinna Kollath, University of Geneva

Correlation dynamics and decoherence in ultracold quantum gases

University of Geneva 

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. Further we investigate the destruction of coherence by dissipation.