Ultrafast dynamic control of spin and charge density oscillations in a GaAs quantum well

The generation and monitoring of real time collective oscillations of electrons in an modulation-doped GaAs quantum well was discussed using subpicosecond laser pulses. It was found that the observed frequencies matched those of intersubband spin- and charge-density excitations. It was observed that light coupled to coherent density fluctuations through resonant stimulated Raman scattering. Analysis shows that the amplitudes of the corresponding oscillations was independently controlled by using shaped pulses of the proper polarization.