Metasurface-mediated quantum entanglement via bound states in the continuum

Scalable quantum technologies demand entanglement between many distant quantum emitters (QEs), for which we propose using high-Q, spatially extended bound states in the continuum (BICs) in all-dielectric metasurfaces. We show that QE-BIC coupling efficiencies (β-factors) can exceed $80%$, comparable to waveguides even without further mode engineering, but within a 2D geometry that naturally accommodates large QE arrays and relaxes strict emitter placement. Inter-QE entanglement is generated faster than in free space, is significantly amplified, and persists over several resonant wavelengths. Optimality requires large β-factors but moderately small Purcell factors. Our results establish all-dielectric metasurfaces as a practical, scalable platform for leading-edge quantum photonics.