Ultrafast dynamics in a single CdSe/ZnSe quantum dot

We have performed two-color femtosecond pump-probe spectroscopy on a single self-assembled CdSe/ZnSe quantum dot. The transient quantum dynamics was probed with resonant excitation and detection. Microphotoluminescence (PL) spectrum of the quantum dot is also measured. The resonant generation of a highly energetic exciton ("hot exciton") by the pump pulse results in an instantaneous bleaching of the exciton resonance at 2.112 eV via Coulomb renormalization of the transition.