Quantum information and sensing with structured light

Vectorial modes of light, a type of structured light where the polarization varies across the beam profile, are a useful tool both in classical and quantum applications. In quantum communication, for instance, these modes enable rotational invariant protocols, therefore overcoming the requirement of a shared reference frame between users. Moreover, structured light can be a resource for enhanced sensing purposes as for instance in the "photonic gears" technique. This quantum inspired scheme enables a boost of sensitivity in mechanical displacements measurement thanks to a bidirectional mapping between the polarization state and a properly tailored vectorial mode of a paraxial light beam. Finally, we will discuss how quantum interference can be controlled and tailored for structured light modes, therefore providing a key ingredient for exploiting the full potential of complex light in the quantum domain.