Spreading of correlations and entanglement after a quench in the   one-dimensional Bose-Hubbard model
  We investigate the spreading of information in a one-dimensional Bose-Hubbard system after a sudden parameter change. In particular, we study the time-evolution of correlations and entanglement following a quench. The investigated quantities show a light-cone like evolution, i.e. the spreading with a finite velocity. We discuss the relation of this veloctiy to other characteristic velocities of the system, like the sound velocity. The entanglement is investigated using two different measures, the von-Neuman entropy and mutual information. Whereas the von-Neumann entropy grows rapidly with time the mutual information between two small subsystems can as well decrease after an initial increase. Additionally we show that the static von Neuman entropy characterises the location of the quantum phase transition. 
Andreas Laeuchli, Corinna Kollath