Quantum interactions of LG beams

Summary form only given. The aim of this work is to promote the development of a quantum framework for formulating the interactions of Laguerre-Gaussian beams and others of related structure, in which a helical wavefront confers an endowment with orbital angular momentum. We explore changes in selection rules in the context of non-linear processes, especially second harmonic generation and sum-frequency generation processes, and the effects of higher electric and magnetic multipoles. We evaluate the forces and torques that can act on molecules endowed with electric or magnetic multipoles.