Luminescence quantum beats of strain-induced GaAs quantum dots

Quantum beats of the strain-induced GaAs quantum dots were observed in the time-resolved photoluminescence in the magnetic field parallel and perpendicular to the growth direction. Quantum beats observed under the longitudinal magnetic field are caused by quantum interference of bright excitons showing Zeeman splitting. The oscillation period depends on the angle between the growth direction of the crystal and the magnetic field. Analysis based on the spin Hamiltonian for excitons explains the observed data and gives g factors 0.51, 0.17, and 0.34 to the exciton, electron, and heavy hole, respectively. Quantum beats coming from electron Larmor precession were observed under the transverse magnetic field. The isotropic electron g factor is observed in contrast to the anisotropic electron g factor for the corresponding quantum well and is ascribed to the strain-induced opposite energy shift of heavy- and light-hole bands.