Thermalization and dynamics in the single-impurity Anderson model

Abstract

A thorough test of the eigenstate thermalization hypothesis (ETH) for the single-impurity Anderson model, performed with the aid of the numerical renormalization group (NRG) method, finds good support for ETH. The mechanism responsible for effective thermalization within the NRG can be identified as Anderson orthogonality: the more charge that needs to flow to or from infinity after applying a local excitation within the Wilson chain, the more the system looks thermal afterwards at an increased temperature. For the same reason, however, thermalization fails if charge rearrangement after the excitation remains mostly local. In these cases, the different statistical ensembles lead to different results, and their behavior needs to be understood as a microscopic quantum quench only. This analysis provides new and important insight into the process of thermalization and dynamics of systems exhibiting strong, nontrivial correlations.