Coherent control of resonant quantum well emission

We have investigated the manipulation of the phase and amplitude of the sta te of a three-level exciton system by excitation with pairs of phase-locked optical pulses. We demonstrate coherent control over the phase of quantum beating between the light- and heavy-hole excitons which are the components of the system. The state of the system is monitored by rime-resolved detec tion of the resonant secondary emission coupled out of the system in non-ph ase-matched directions by virtue of the static disorder. We show that the a mplitude of the coherent manipulation must diminish as a function of time d elay between the components of the pulse pair in a way which takes into acc ount both the dephasing of the excitons and their unphasing which arises fr om inhomogeneous broadening.