  It is demonstrated how the exciton and the biexciton state of a quantum dot
can be prepared with high fidelity on a picosecond time-scale by driving the
dot with a strong laser pulse that is tuned above the exciton resonance for
exciton preparation and in resonance with the exciton transition for biexciton
preparation. The proposed schemes make use of the phonon-induced relaxation
towards photon dressed states in optically driven quantum dots and combine the
simplicity of Rabi flopping with the robustness of adiabatic rapid passage
schemes. Our protocols allow for an on-demand, fast and almost perfect state
preparation even at strong carrier-phonon interaction where other schemes fail.
In fact, the performance of the presented protocols is shown to be the better
the stronger the carrier-phonon interaction is.
