Hiding images in quantum correlations

Photon-pair correlations in spontaneous parametric down conversion (SPDC) processes are ubiquitous in quantum photonics. In this work, we engineer these correlations by imaging arbitrarily chosen objects in the second order correlations of spatially-entangled photon pairs produced by type-I SPDC in a non-linear crystal. Our approach is effective with both amplitude and phase objects, even when the beam intensity is spatially shaped. Additionally, we show that it is resistant to scattering by applying wavefront shaping techniques. We also find that certain phase patterns can refocus through the scattering medium exclusively with photon pairs, and not with classical coherent light. Consequently, the transmission of an image through the scattering medium is only possible if it is correlation encoded; coherent light alone cannot reconstruct the image. Our approach enables the transmission of complex, high-dimensional information using quantum correlations of photons, offering significant potential for advancing quantum communication and imaging protocols.