  We provide evidence that a clean kicked Bose-Hubbard model exhibits a
many-body dynamically localized phase. This phase shows ergodicity breaking up
to the largest sizes we were able to consider. We argue that this property
persists in the limit of large size. The Floquet states violate eigenstate
thermalization and then the asymptotic value of local observables depends on
the initial state and is not thermal. This implies that the system does not
generically heat up to infinite temperature, for almost all the initial states.
Differently from many-body localization here the entanglement entropy linearly
increases in time. This increase corresponds to space-delocalized Floquet
states which are nevertheless localized across specific subsectors of the
Hilbert space: In this way the system is prevented from randomly exploring all
the Hilbert space and does not thermalize.
