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

Abstract: Coherent control of quantum emitters is essential for scalable quantum photonic technologies. The recently proposed swing-up of quantum emitter (SUPER) scheme enables the coherent preparation of excitons via off-resonant, red-detuned laser pulses, offering highly efficient single-photon generation. We present a systematic study of SUPER excitation applied to a single GaAs quantum dot in a low-Q micropillar cavity. After identifying optimal excitation conditions, we benchmark the SUPER scheme against above-band, p-shell, and two-photon biexciton excitation (TPE). Despite requiring higher excitation powers, SUPER achieves near-unity population inversion ($\sim$95 %) and high single-photon purity ($g^{(2)}=0.03$), comparable to TPE, while also yielding a shortened exciton decay time ($\sim$200 ps), indicative of direct, efficient exciton preparation. A polarization-resolved analysis reveals that, when both excitation and collection are aligned with the exciton dipole, SUPER results in a highly polarized single-photon emission exceeding resonant TPE saturation by a factor of 1.45. Under optimal excitation conditions, we also observe biexciton preparation via a distinct SUPER resonance, confirmed by unpolarized exciton emission, extended lifetime due to the biexciton-exciton cascade, and biexciton emission, constituting the first experimental demonstrations of biexciton preparation under SUPER. These findings are in good agreement with a proposed four-level theoretical model including the biexciton. We also report that, strikingly, a slight misalignment of laser polarization induces an additional SUPER resonance that selectively populates the orthogonal exciton state without altering the nominal excitation polarization. These findings establish the SUPER scheme as a versatile tool for state-selective exciton and biexciton control, with strong potential for quantum photonic applications.