# An Upper Bound on the Rate of Information Transfer in Optical Vortex Beams

## TL;DR

This paper establishes an upper limit on the amount of information that can be transferred using optical vortex beams, which carry orbital angular momentum, based on recent findings about their group velocity.

## Contribution

It provides a theoretical upper bound on information transfer rates in optical vortex beams, linking orbital angular momentum to practical communication limits.

## Key findings

- Group velocity is inversely proportional to the orbital quantum number l.
- An upper bound on information transfer rate in optical vortex beams is derived.
- Optical vortex states form a potentially infinite basis for encoding information.

## Abstract

Light endowed with orbital angular momentum, commonly termed optical vortex light, has an azimuthal phase indexed by the orbital quantum number $l$. In contrast to the two basis states of the optical spin angular momentum, the interest in the information content of optical vortex beams is centred on the assumption that $\lvert{l}\rangle{}$ forms a countably infinite set of basis states. The recent experimental observation that group velocity is inversely proportional to $l$ provides a theoretical basis for a practical measure of information transfer. This Letter sets an upper bound on that measure.