  Existing techniques for synthesizing gauge fields are able to bring a
two-dimensional cloud of harmonically trapped bosonic atoms into a regime where
the occupied single-particle states are restricted to the lowest Landau level
(LLL). Repulsive short-range interactions drive various transitions from fully
condensed into strongly correlated states. In these different phases we study
the response of the system to quasihole excitations induced by a laser beam. We
find that in the Laughlin state the quasihole performs a coherent constant
rotation around the center, ensuring conservation of angular momentum. This is
distinct to any other regime with higher density, where the quasihole is found
to decay. At a characteristic time, the decay process is reversed, and revivals
of the quasihole can be observed in the density. Measuring the period and
position of the revival can be used as a spectroscopic tool to identify the
strongly correlated phases in systems with a finite number of atoms.
