  We study theoretically quantum dynamics of interacting bosons in artificial
magnetic fields as engineered in recent ultracold atomic experiments, where
quantum cyclotron orbital motion has been observed. With exact numerical
simulations and perturbative analyses, we find that interactions induce damping
in the cyclotron motion. The damping time is found to be dependent on
interaction and tunneling strengths monotonically, while its dependence on
magnetic flux is non-monotonic. Sufficiently strong interactions would render
bosons dynamically localized inhibiting the cyclotron motion. The damping
predicted by us can be construed as an interaction-induced quantum decoherence
of the cyclotron motion.
