  We study the phonon-induced dephasing of the exciton state in a quantum dot
excited by a sequence of ultra-short pulses. We show that the multiple-pulse
control leads to a considerable improvement of the coherence of the optically
excited state. For a fixed control time window, the optimized pulsed control
often leads to a higher degree of coherence than the control by a smooth single
Gaussian pulse. The reduction of dephasing is considerable already for 2-3
pulses.
