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

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 structure 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.