Unidirectional and collective emission of integrated quantum emitters
Phys. Rev. Applied 26, 044044 – Published 15 October, 2026
DOI: https://doi.org/10.1103/vmkn-2hc8
Abstract
Controlling the radiative dynamics of quantum emitters in structured environments is fundamental to quantum optics and light-matter interaction engineering. Photonic crystal slabs offer a versatile platform for engineering emission anisotropy, yet simultaneously achieving high directionality, radiative efficiency, and collective coherence remains a central challenge. In this work, we present a comprehensive framework that quantifies directional emission through an iso-frequency-contour straightness parameter combined with spatial Fourier analysis of the radiation field. For single emitters in square-lattice slabs, we show that dielectric and geometric tuning can simultaneously realize a high Purcell factor (PF) and robust unidirectional propagation. Extending the analysis to multiemitter arrays, however, reveals an intrinsic trade-off of open nanophotonic systems: the extreme local-field confinement that maximizes the PF inherently suppresses the long-range coherent coupling required for cooperative superradiance. By operating in a moderate Purcell regime with emitters centered in air holes, we demonstrate that highly directional propagation and scalable collective emission can coexist. We further examine lattice symmetry and find that, within the parameter regimes specifically evaluated, square lattices provide more robust single-channel unidirectional emission than the triangular lattices considered. These results establish design principles for integrated quantum light sources with controlled spatiotemporal coherence.
