Coherent oscillations of a wave packet in a semiconductor double-quantum-well structure

We present the first observation of the spatial dynamics of a wavepacket in a solid. Using an ultrashort laser pulse, we create an excitonic wavepacket in one well of an asymmetric double quantum well structure. The oscillation of this wavepacket from one well to another and back is traced by time- resolved pump-probe spectroscopy as well as time- resolved degenerate fourwave-mixing. We present results for two GaAs/AlGaAs double quantum wells with oscillation periods of about 1.3ps and 800fs, respectively. The experimental observations are compared with a theory that shows that the two experimental techniques give complementary information about the relaxation dynamics of the coupled system. The analysis of the experiment explains the strong damping of the oscillations by the fast thermalization between the delocalized states. We present the first study of the dynamics of an extended electronic wave packet in a solid. The wave packet is created in a GaAs/AlGaAs double-quantum-well stru cture by ultrashort pulse excitation. We observe the oscillatory motion of the wave packet between the two wells by using time-resolved degenerate four-wave-mixing and pump-and-probe spectroscopy