Metasurface-enabled quantum holograms with hybrid entanglement

Metasurfaces, with their capability to control all possible dimensions of light, have become integral to quantum optical applications, including quantum state generation, operation, and tomography. We utilize a metasurface to generate polarization–hologram hybrid entanglement between a signal–idler photon pair to construct a quantum hologram. The properties of the quantum hologram can be revealed by collapsing the polarization degree of freedom of the idler photon, inducing interference between two holographic states of the signal photon as a meaningful and selective erasure of the holographic content. On the contrary, interference disappears when the idler photon is detected without observing polarization. This process can be further interpreted as a quantum holographic eraser, where the erasing action is visualized with erased contents in holograms. Our construction of a polarization–hologram hybrid entangled state with metasurfaces will be useful for quantum communication with enhanced robustness, anticounterfeiting applications through the additional quantum degrees of freedom or phase difference between two holographic states, and as an emerging platform for exploring fundamental quantum concepts for entanglement and nonlocality.