An optical vortex is a laser beam with a helical wavefront. Its main property is a twisted Poynting vector and an associated orbital angular momentum (OAM) of the photon whose value is quantized by an integer l which is the direction and number of the helix branches. The OAM is one of the variables that can be used for quantum technologies.
The Recife group was a pioneer in the use and understanding of OAM in 4-wave mixing showing its transfer, storage and retrieval. I will give the evolution of the field which today leads to OAM entanglement and quantum simulation using OAMs.