Quantum orbital angular momentum of elliptically-symmetric light

TL;DR

This paper provides a quantum mechanical analysis of elliptically-symmetric light fields, revealing unique properties of their orbital angular momentum that could impact quantum communication and information processing.

Contribution

It introduces a quantum formalism for Ince-Gauss modes, showing how their orbital angular momentum varies with ellipticity and uncovering novel behaviors.

Findings

Orbital angular momentum varies non-monotonically with ellipticity

Existence of stable beams with non-integer orbital angular momentum

Orthogonal modes can share the same orbital angular momentum

Abstract

We present a quantum mechanical analysis of the orbital angular momentum of a class of recently discovered elliptically-symmetric stable light fields --- the so-called Ince-Gauss modes. We study, in a fully quantum formalism, how the orbital angular momentum of these beams varies with their ellipticity and discover several compelling features, including: non-monotonic behavior, stable beams with real continuous (non-integer) orbital angular momenta, and orthogonal modes with the same orbital angular momenta. We explore, and explain in detail, the reasons for this behavior. These features may have application to quantum key distribution, atom trapping, and quantum informatics in general --- as the ellipticity opens up a new way of navigating the photonic Hilbert space.