Waveguide excitation and spin pumping of chirally coupled quantum dots
S. Germanis, Xuchao Chen, R. Dost, D. Hallett, Edmund Clarke, Pallavi Patil, M. S. Skolnick, L. R. Wilson, Hamidreza Siampour, A. Mark Fox
Abstract
On-chip excitation of single quantum emitters is a key requirement for developing scalable quantum photonic technologies. Here, we report a remote excitation protocol on an integrated semiconductor chip, in which a single quantum dot (QD) is driven in-plane via a photonic-crystal waveguide through a p -shell optical transition. The chirality of the waveguide mode is exploited to achieve both directional absorption and directional emission, resulting in a substantial enhancement in directional contrast, as measured for the Zeeman components of the waveguide-coupled QD. This remote excitation scheme enables near-unity directionality (≥0.95) across ∼56% of the waveguide area, with significant overlap with the Purcell-enhanced region, where the electric field intensity profile is near its peak. In contrast, conventional out-of-plane local excitation yields only ∼25% overlap. This enhancement increases the likelihood of locating Purcell-enhanced QDs in regions that support high directionality, allowing the experimental demonstration of a six-fold enhancement in the decay rate of a QD with directionality of 90±3%. The remote p-shell excitation protocol thus establishes a benchmark for waveguide quantum optics by combining Purcell enhancement with high directionality. This approach enables efficient on-chip spin initialization and control in solid-state quantum technologies operating in high-β-factor regimes, with implications for scalable quantum networks and integrated devices.