Thermalization after canonical quenches

After preparing a macroscopic, isolated system out of equilibrium, we generically expect it to relax towards a thermal equilibrium state over time. Understanding this ubiquity of thermalization from the basic laws of quantum mechanics is an ongoing research endeavor, which led to the discovery of possible relaxation mechanisms (e.g., the eigenstate thermalization hypothesis/ETH), but also identified situations where systems defy the fate of thermalization (e.g., integrability, Hilbert space fragmentation). I will present various recent analytical insights into the relaxation of quantum many-body systems after canonical quenches, meaning that the system is brought out of equilibrium by a sudden change of some of its parameters. The results include necessary conditions for thermalization, a proof of rethermalization after local quenches, and a subtlety in the ETH that challenges its perceived fundamental role for thermalization.