Rabi-flopping of the ground state exciton in a single self-assembled quantum dot

We report Rabi-oscillations of the ground state exciton in a single self-assembled quantum dot (QD). Experimentally, we apply a photocurrent (PC) technique, that enables us to monitor the occupation probability of the exciton state by measuring the dc tunneling current out of the QD. Coherent PC spectrocopy was performed by resonant ps-excitation of the ground state exciton. Rabi-oscillations are shown to be directly reflected in the PC. In the case of π-pulse excitation, we receive a quantitative PC given by I=f×e, with the repetition frequency of the experiment f and the elementary charge e. In our experiment we nearly reach this maximum current showing that our experiment acts as a quantitative proof for Rabi-flopping in a single QD. In a systematic study of field-dependence we find Rabi-oscillations with reduced PC amplitude.