COHERENT OPTICAL CONTROL OF THE QUANTUM STATE OF A SINGLE QUANTUM-DOT

Picosecond optical excitation was used to coherently control the excit ation in a single quantum dot on a time scale that is short compared w ith the time scale for loss of quantum coherence. The excitonic wave f unction was manipulated by controlling the optical phase of the two-pu lse sequence through timing and polarization. Wave function engineerin g techniques, developed in atomic and molecular systems, were used to monitor and control a nonstationary quantum mechanical state composed of a superposition of eigenstates. The results extend the concept of c oherent control in semiconductors to the limit of a single quantum sys tem in a zero-dimensional quantum dot.