Physical Review A
High-dimensional quantum nature of ghost angular Young’s diffraction
Lixiang Chen, Jonathan Leach, Barry Jack, Miles J. Padgett, Sonja Franke‐Arnold, Weilong She
Abstract
We propose a technique to characterize the dimensionality of entangled sources affected by any environment, including phase and amplitude masks or atmospheric turbulence. We illustrate this technique on the example of angular ghost diffraction using the orbital angular momentum (OAM) spectrum generated by a nonlocal double slit. We realize a nonlocal angular double slit by placing single angular slits in the paths of the signal and idler modes of the entangled light field generated by parametric down-conversion. Based on the observed OAM spectrum and the measured Shannon dimensionality spectrum of the possible quantum channels that contribute to Young's ghost diffraction, we calculate the associated dimensionality ${D}_{\mathrm{total}}$. The measured ${D}_{\mathrm{total}}$ ranges between 1 and 2.74 depending on the opening angle of the angular slits. The ability to quantify the nature of high-dimensional entanglement is vital when considering quantum information protocols.