  We investigate the influence of the photon statistics on the excitation
dynamics of a single two level system. A single semiconductor quantum dot
represents the two level system and is resonantly excited either with coherent
laser light, or excited with chaotic light, with photon statistics
corresponding to that of thermal radiation. Experimentally, we observe a
reduced absorption cross-section under chaotic excitation in the steady-state.
In the transient regime, the Rabi oscillations observable under coherent
excitation disappear under chaotic excitation. Likewise, in the emission
spectrum the well-known Mollow triplet, which we observe under coherent drive,
disappears under chaotic excitation. Our observations are fully consistent with
theoretical predictions based on the semi-classical Bloch equation approach.
