Fisica Matematica Quench dynamics and memory preservation in quantum integrable systems
Spyros Sotiriadis
12-04-2016 - 14:30 AULA 311 (SEMINARI) Largo San L. Murialdo,1
One of the foundations of statistical physics is that only minimal information is required for the description of macroscopic systems. Research in quantum one-dimensional integrable systems out-of-equilibrium has recently revealed relaxation towards a non-thermal statistical ensemble that violates this principle due to the presence of an infinite number of local integrals of motion. The information content of this ensemble remains however a riddle. By studying the dynamics after suddenly switching-off the interactions in an isolated quantum system (a so-called quantum quench), we will show that the time evolution under a massive Gaussian field theory erases all memory of non-Gaussian correlations that are present in the initial state, keeping information only about the initial two-point correlation function. On the other hand, in the massless case in one spatial dimension we will show that an enormous amount of information about the initial state survives even at infinitely large times, in contrast to earlier expectations. We provide an intuitive explanation of the above results based on the cluster decomposition principle and the hydrodynamic character of the evolution. Lastly we will discuss applications to cold atom experiments and generalisations to spin chains. |