Exciton and biexciton preparation via coherent swing-up excitation in a GaAs quantum dot embedded in a micropillar cavity

Coherent control of quantum emitters is essential for scalable quantum photonic technologies. The recently
proposed swing up of the quantum emitter population (SUPER) scheme allows efficient and coherent state
preparation via off-resonant, red-detuned laser pulses, simplifying laser suppression and enhancing photon
collection. We present a systematic study of SUPER excitation applied to a single GaAs quantum dot in a
low-Q micropillar cavity. We first identify the optimal excitation conditions for SUPER, and then compare
the key figures of merit against the well-established two-photon excitation (TPE). Despite requiring higher
excitation powers, SUPER achieves near-unity population inversion of the exciton state (∼95%) and high
single-photon purity (g(2) = 0.03) comparable to that under TPE, while also exhibiting a shortened decay time
(∼200 ps) reducing the time jitter in the exciton population. A polarization-resolved analysis reveals that when
both excitation and collection are aligned with one of the exciton dipoles, SUPER results in highly polarized
single-photon emission, exceeding the resonant TPE saturation by a factor of 1.45. Under optimized excitation
conditions, we also observe biexciton preparation via a distinct SUPER resonance, constituting an experimental
demonstration of biexciton preparation using SUPER. These findings are in good agreement with a proposed
four-level theoretical model that incorporates the biexciton state. Furthermore, we report that, strikingly, a
slight misalignment of laser polarization induces an additional SUPER resonance that selectively populates the
orthogonal exciton dipole, without altering the nominal excitation polarization. This unexpected behavior reveals
a new degree of freedom for coherent state preparation. Our findings establish the SUPER scheme as a versatile
tool for state-selective exciton and biexciton control, with strong potential for quantum photonic applications.