The quest for the perfect single-photon source includes finding the optimal protocol for exciting the quantum emitter. Coherent optical excitation was, up until now, achieved by tuning the laser pulses to the transition frequency of the emitter, either directly or in average. Recently, it was theoretically discovered that an excitation with two red-detuned pulses is also possible where neither of which would yield a significant upperlevel population individually. We show that the so-called swing-up of quantum emitter population (SUPER) scheme can be implemented experimentally with similar properties to existing schemes by precise amplitude shaping of a broadband pulse. Because of its truly off-resonant nature, this scheme has the prospect of powering high-purity photon sources with superior photon count rate.

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Nanoscale bright sources that produce high-purity single photons and high-fidelity entangled photon
pairs are the building blocks to realize high security quantum communication devices. To achieve high
communication rates, it is desirable to have an ensemble of quantum emitters that can be collectively
excited, despite their spectral variability. In case of semiconductor quantum dots, Rabi rotations are
the most popular method for resonant excitation. However, these cannot assure a universal, highly ef-
ficient excited state preparation, due to the sensitivity to excitation parameters. In contrast, Adiabatic
Rapid Passage (ARP), relying on chirped optical pulses, is immune to quantum dot spectral inhomo-
geneity. Here, we show that the robustness of ARP holds true for the simultaneous excitation of the
biexciton states in multiple, spatially separated and spectrally different quantum dots. For positive
chirps, we also find a regime where the influence of phonons relax the sensitivity to spectral detunings
and lower the needed excitation power. Being able to generate high-purity photons from spatially
multiplexed quantum dot sources using the biexciton to ground state cascade is a big step towards the
implementation of high photon rate, entanglement-based quantum key distribution protocols.

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