Delayed thermalization in the mass-deformed Sachdev-Ye-Kitaev model

We study the thermalizing properties of the mass-deformed Sachdev-Ye-Kitaev model, in a regime of parameters where the eigenstates are ergodically extended over just portions of the full Fock space, as an all-to-all toy model of many-body localization (MBL). Our numerical results strongly support the hypothesis that, although considerably delayed, thermalization is still present in this regime. Our results add to recent studies indicating that MBL should be interpreted as a strict Fock-space localization.