  In the study of the thermalization of closed quantum systems, the role of
kinetic constraints on the temporal dynamics and the eventual thermalization is
attracting significant interest. Kinetic constraints typically lead to
long-lived metastable states depending on initial conditions. We consider a
model of interacting hardcore bosons with an additional kinetic constraint that
was originally devised to capture glassy dynamics at high densities. As a main
result, we demonstrate that the system is highly prone to localization in the
presence of uncorrelated disorder. Adding disorder quickly triggers long-lived
dynamics as evidenced in the time evolution of density autocorrelations.
Moreover, the kinetic constraint favors localization also in the eigenstates,
where a finite-size transition to a many-body localized phase occurs for much
lower disorder strengths than for the same model without a kinetic constraint.
Our work sheds light on the intricate interplay of kinetic constraints and
localization and may provide additional control over many-body localized phases
in the time domain.
