Phys.org  June 6, 2024 All-optical generation of photonic vortices requires sufficiently strong nonlinearity that is typically achieved in the classical optics regime. Researchers in Israel realized quantum vortices of photons that resulted from a strong photon-photon interaction in a quantum nonlinear optical medium. The interaction caused faster phase accumulation for copropagating photons, producing a quantum vortex-antivortex pair within the two-photon wave function. For three photons, the formation of vortex lines and a central vortex ring confirmed the existence of a genuine three-photon interaction. The wave function topology, governed by two- and three-photon bound states, imposed a conditional phase shift of […]