Creation and characterization of vector vortex modes for classical and quantum communication

TL;DR

This paper reviews the creation, characterization, and propagation of vector vortex modes in classical and quantum communication, highlighting their potential and challenges in information transfer.

Contribution

It provides new insights into the propagation behavior of vector vortex modes and compares detection schemes, advancing understanding in classical and quantum communication applications.

Findings

Modal cross-talk causes decay of vector states into scalar modes

Probabilistic detection reduces quantum communication benefits

Deterministic detection improves information preservation

Abstract

Vector vortex beams are structured states of light that are non-separable in their polarisation and spatial mode, they are eigenmodes of free-space and many fibre systems, and have the capacity to be used as a modal basis for both classical and quantum communication. Here we outline recent progress in our understanding of these modes, from their creation to their characterization and detection. We then use these tools to study the propagation behaviour of such modes in free-space and optical fibre and show that modal cross-talk results in a decay of vector states into separable scalar modes, with a concomitant loss of information. We present a comparison between probabilistic and deterministic detection schemes showing that the former, while ubiquitous, negates the very benefit of increased dimensionality in quantum communication while reducing signal in classical communication links. This work provides a useful introduction to the field as well as presenting new findings and perspectives to advance it further.