  In this work we demonstrate that non-random mechanisms that lead to
single-particle localization may also lead to many-body localization, even in
the absence of disorder. In particular, we consider interacting spins and
fermions in the presence of a linear potential. In the non-interacting limit,
these models show the well known Wannier-Stark localization. We analyze the
fate of this localization in the presence of interactions. Remarkably, we find
that beyond a critical value of the potential gradient, these models exhibit
non-ergodic behavior as indicated by their spectral and dynamical properties.
These models, therefore, constitute a new class of generic non-random models
that fail to thermalize. As such, they suggest new directions for
experimentally exploring and understanding the phenomena of many-body
localization. We supplement our work by showing that by employing machine
learning techniques, the level statistics of a system may be calculated without
generating and diagonalizing the Hamiltonian, which allows a generation of
large statistics.
