Quantitative phase gradient microscopy with spatially entangled photons

We present an entanglement-based quantitative phase gradient microscopy technique that employs principles from quantum ghost imaging and ghost diffraction. In this method, a transparent sample is illuminated by both photons of an entangled pair - one detected in the near-field (position) and the other in the far-field (momentum). Due to the strong correlations offered by position-momentum entanglement, both conjugate observables can be inferred nonlocally, effectively enabling simultaneous acces...