Structured light, transmission and scattering

Numerous theoretical and experimental studies have established the principle that beams conveying orbital angular momentum offer a rich scope for information transfer. However, it is not clear how far it is practicable to operate such a concept at the single-photon level - especially when such a beam propagates through a system in which scattering can occur. In cases where scattering leads to photon deflection, it produces losses; however in terms of the retention of information content, there should be more concern over forward scattering. Based on a quantum electrodynamical formulation of theory, this paper aims to frame and resolve the key issues. A quantum amplitude is constructed for the representation of single and multiple scattering events in the propagation an individual photon, from a suitably structured beam. The analysis identifies potential limitations of principle, undermining complete fidelity of quantum information transmission.