Effect of Rare Fluctuations on the Thermalization of Isolated Quantum Systems

摘要: We consider the question of thermalization for isolated quantum systems after a sudden parameter change, so-called quench. In particular, we investigate prerequisites thermalization, focusing on statistical properties time-averaged density matrix and expectation values observables in final eigenstates. find that eigenstates, which are rare compared to typical ones sampled by microcanonical distribution, responsible absence some infinite integrable models play an important role nonintegrable finite size, such as Bose-Hubbard model. stress importance size effects discuss two scenarios thermalization.