Spatially resolving classical and quantum entanglement with structured photons

Nonseparability in classical and quantum states of light gives rise to the notions of classical (local) and quantum (nonlocal) entanglement, usually defined as global features of the fields and states. Here we use concurrence as a measure of this nonseparability and show that it can be spatially resolved, revealing regions of maximum nonseparability and regions with no nonseparability. We use the topical examples of vectorial structured light and its quantum analog, a hybrid spatial mode and polarization entangled states, to test the approach on both local and nonlocal forms of entanglement. Our work has wide reaching implications, for instance, in understanding the spatial dependence of coherence and polarization in vectorial light, as well as in quantum entangled states for imaging, where spatial correlations are vital.