Erasing the orbital angular momentum information of a photon

Quantum erasers with paths in the form of physical slits have been studied extensively and proven instrumental in probing wave-particle duality in quantum mechanics. Here we replace physical paths (slits) with abstract paths of orbital angular momentum (OAM). Using spin-orbit hybrid entanglement of photons, we show that the OAM content of a photon can be erased with a complementary polarization projection of one of the entangled pair. The result is the (dis)appearance of azimuthal fringes based on whether the ``which-OAM'' information was erased. We extend this concept to a delayed measurement scheme and show that the OAM information and fringe visibility are complementary.