  Realizing strongly-correlated topological phases of ultracold gases is a
central goal for ongoing experiments. And while fractional quantum Hall states
could soon be implemented in small atomic ensembles, detecting their signatures
in few-particle settings remains a fundamental challenge. In this work, we
numerically analyze the center-of-mass Hall drift of a small ensemble of
hardcore bosons, initially prepared in the ground state of the
Harper-Hofstadter-Hubbard model in a box potential. By monitoring the Hall
drift upon release, for a wide range of magnetic flux values, we identify an
emergent Hall plateau compatible with a fractional Chern insulator state: the
extracted Hall conductivity approaches a fractional value determined by the
many-body Chern number, while the width of the plateau agrees with the spectral
and topological properties of the prepared ground state. Besides, a direct
application of Streda's formula indicates that such Hall plateaus can also be
directly obtained from static density-profile measurements. Our calculations
suggest that fractional Chern insulators can be detected in cold-atom
experiments, using available detection methods.
