Ultrafast quantum-path interferometry of photo-absorption involving excitons in a GaAs multiple-quantum-well structure

Using a pump-probe protocol with pairs of relative-phase-locked femtosecond pulses, we gathered transient reflectivity measurements from a multiple quantum well structure of GaAs/Al0.3Ga0.7As at 10 K. Quantum beating between heavy-hole and light-hole excitons was observed as an oscillation in the transient reflectivity. Its intensity was coherently controlled by controlling the delay between two successive pump pulses. We found characteristic interference fringes arising from the interference of the photo-induced excitons traversing entangled quantum paths. As established in theory, these fringes are peculiar to this dual-pulse excitation via photo-absorption.

Automated summary

Using a pump-probe protocol, we measured the transient reflectivity of a GaAs/Al0.3Ga0.7As multiple quantum well structure at 10 K. Quantum beating between heavy-hole and light-hole excitons was observed, causing oscillations in the reflectivity. The intensity of these oscillations could be controlled by adjusting the delay between the pump pulses. Additionally, interference fringes were observed, indicating the presence of entangled quantum paths for the photo-induced excitons.