  The dissipative response of a quantum system upon a time-dependent drive can
be exploited as a probe of its geometric and topological properties. In this
work, we explore the implications of such phenomena in the context of
two-dimensional gases subjected to a uniform magnetic field. It is shown that a
filled Landau level exhibits a quantized circular dichroism, which can be
traced back to its underlying non-trivial topology. Based on selection rules,
we find that this quantized circular dichroism can be suitably described in
terms of Rabi oscillations, whose frequencies satisfy simple quantization laws.
Moreover, we discuss how these quantized dissipative responses can be probed
locally, both in the bulk and at the boundaries of the quantum Hall system.
This work suggests alternative forms of topological probes in quantum systems
based on circular dichroism.
