Quantum phase gradient imaging using a nonlocal metasurface system

Abstract

Quantum phase imaging enables the analysis of transparent samples with thickness and refractive index variations in scenarios requiring precise measurements under low-light conditions. Here, we present a compact quantum phase-gradient imaging system integrating a lithium niobate (LiNbO 3 ) metasurface for generating spatially entangled photon pairs and a silicon (Si) metasurface for phase gradient extraction. By leveraging nonlocal resonances, the LiNbO 3 metasurface enables efficient spontaneous parametric down-conversion (SPDC) with all-optically angularly tunable emissio..