Ultrafast Dynamic Control of Spin and Charge Density Oscillations in a GaAs Quantum Well

TL;DR

This paper demonstrates the ultrafast generation and control of spin and charge density oscillations in a GaAs quantum well using shaped laser pulses, enabling independent manipulation of these collective modes.

Contribution

It introduces a method to selectively control spin and charge density oscillations in quantum wells via resonant stimulated Raman scattering with shaped laser pulses.

Findings

Successful real-time monitoring of electron oscillations.

Independent control of spin and charge modes achieved.

Oscillation frequencies match theoretical intersubband excitations.

Abstract

We use subpicosecond laser pulses to generate and monitor in real time collective oscillations of electrons in a modulation-doped GaAs quantum well. The observed frequencies match those of intersubband spin- and charge-density excitations. Light couples to coherent density fluctuations through resonant stimulated Raman scattering. Because the spin- and charge-related modes obey different selection rules and resonant behavior, the amplitudes of the corresponding oscillations can be independently controlled by using shaped pulses of the proper polarization.