Temporal coherent control in semiconductor quantum structures

Temporal coherent control experiment have been performed on semiconductor q uantum well structures, using a sequence of polarized excitation pulses. Th e oscillatory behaviour of the populations , spin and alignment of the exci ton states are observed through the time resolved secondary emission when t he time separation between the two excitation pulses is varied. We show tha t, in specular detection direction, for bare quantum wells at 10 K and low exciton densities, the oscillations amplitude decay is determined by the ex citon inhomogeneous broadening. In non-specular detection directions howeve r, when the SE is dominated by resonant Rayleigh scattering, the decay is l onger and becomes temperature dependent, which strongly supports that it is now determined by the exciton dephasing time.