Photon–phonon entanglement in the acousto-optic interaction of vector beams

Abstract

We demonstrate that acousto-optic diffraction under certain conditions can be accompanied by inter-system photon–phonon entanglement. A photon diffracted during Stokes acousto-optic interaction of acoustic and optical vector beams represents a vector beam that manifests the intra-system entanglement between its states characterized by the different signs of circular polarization and orbital angular momentum. At the same time, a diffracted photon and an acoustic phonon emitted in the process of acousto-optic interaction demonstrate the inter-system entanglement between their circularly polarized vortex states.