Figure 1

(a) Schematic SQD energy diagram. The exciton is excited to the first excited state, $|x⟩$ ($|y⟩$), then relaxes nonradiatively to the excitonic ground state, $|g⟩$, and finally radiatively decays back to the vacuum state, $|v⟩$ (no exciton), emitting $x$- ($y$)-polarized PL. (b) Laser polarization.Reuse & Permissions

Figure 2

Theoretical evolution of the three-level V system as a function of the effective pulse area, for various initial conditions and effective polarization angles.Reuse & Permissions

Figure 3

Experimental evolution of the three-level V system, using single-pulse (left) and two-pulse excitation (right). (a) $y$-polarized and (b) $x$-polarized PL signal as a function of pulse area, for an excitation polarization angle $\alpha =\pi /4$. The difference $\mathrm{PL}(y)-\mathrm{PL}(x)$ is plotted in (c). (d) $y$-polarized and (e) $x$-polarized PL signal as a function of pulse area, using a $\pi$ prepulse with $\alpha =\pi /2$. The temporal delay between the two pulses was fixed, while the pulse area of the second pulse with $\alpha =\pi /4$ was varied. For each value of the pulse area, the relative phase between the two pulses was scanned over one period and the PL maxima and minima were recorded. The solid lines represent the simulated envelopes. (f) Difference between the averages of $\mathrm{PL}(x)$ and $\mathrm{PL}(y)$. The schematics at the bottom are meant to illustrate the population floppings pictorially.Reuse & Permissions