Signatures of bath-induced quantum avalanches in a many-body–localized system

Many-body localization has been established as a robust exception of thermalization, yet its fate remains unclear when being brought in contact with a thermal inclusion. We realize a many-body-localized system coupled to a thermal inclusion of different size and study its dynamics. We observe accelerated transport from the inclusion to the localized system, driven by a quantum avalanche propagating through the localized system. To investigate how the avalanche develops, we probe the single-site entropy and study the thermalization of the system. Moreover, multipoint correlations between the inclusion and the localized system are evaluated to look for the existence of high-order process. Our study presents interesting signals regarding the stability of many-body-localized systems and their critical behavior.