Excitation of complex spin dynamics patterns in a quantum-dot electron spin ensemble

We exploit the flexibility offered by an (In, Ga)As/GaAs quantum dot spin ensemble to demonstrate that complex dynamic evolutions can be excited in the ensemble magnetization and accessed by tailored pulsed laser protocols. The modes for spin precession about a magnetic field are adapted to the periodic excitation protocol such that at specific times the magnetization can effectively be decomposed in two, three, or four equal components with angles of pi, 2 pi/3, or pi/2 between them. Optical orientation of these components by an additional laser pulse leads to the generation of higher harmonics in the spin precession, as evidenced by time-resolved ellipticity measurements.