  Magneto-optical effect is a fundamental but broad concept in magnetic
mediums. Here we propose a scheme for its quantum emulation using ultracold
atoms. By representing the light-medium interaction in the quantum-emulation
manner, the artificial magneto-optical effect emerges under an entirely
different mechanism from the conventional picture. The underlying polarization
state extracted in the synthetic dimension displays a different response to
various experimental setups. Notably, the magneto-optical rotation is related
to the bulk topology in synthetic dimensions, and thus provides an unambiguous
evidence for the desired topological magneto-optical effect, which has not been
developed hitherto in ultracold atoms. This scheme is simple and feasible, and
can be realized by current experimental techniques. The implementation of the
scheme is able to offer an intriguing platform for exploring topological
magneto-optical effects and associated physics.
