Coherent dynamics of the swing-up excitation technique

Efficiently exciting quantum two-level systems in the solid state is a key focus in quantum technologies. Balancing efficient filtering of quantum emission, spin- and polarization preservation, coherence, and ensuring good photon quality has led to a variety of excitation methods. However, each scheme comes with drawbacks, often limited to specific setups or level schemes. Recently, Bracht et al. proposed a technique based on two red-detuned excitation pulses which enable a coherent high-fidelity swing-up effect of the population to the excited state, with successful demonstration of its functionality by Karli et al..

In this contribution, we study the coherent dynamics of the swing-up technique with an InGaAs quantum dot. We explore the multidimensional excitation parameter space to identify optimal conditions for high-fidelity population inversion, revealing distinct resonances and assessing parameter interdependence - both in experiment and numerical simulation.

Furthermore, we analyze the single-photon performance of our two-level system under swing-up excitation, finding near-perfect single-photon purity with a raw value of g⁽²⁾(0)= 0.033. In contrast, the measured indistinguishability is limited to v_HOM= 0.439 which can be attributed to the impact of the high laser intensities on the semiconductor environment of the quantum dot. We conclude that the method is very promising, although further engineering is required to make it suitable for applications.