arXiv:2302.05478 · Journal of Modern Optics

On the paraxial approximation in quantum optics II: henochromatic modes of a Maxwell field

M. Fernanda Jongewaard de Boer, Christopher Beetle

Published Mar 3, 2026• 1 citation

Abstract

A companion paper Beetle and Jongewaard de Boer (The paraxial approximation in quantum optics I: henochromatic modes of a scalar field. J Mod Opt. 2025) has argued that the best way to associate single-particle quantum states of a scalar field to the modes of a narrowly collimated beam of classical radiation modelled in the paraxial approximation uses the ‘henochromatic’ states previously introduced by Sudarshan et al. (Paraxial-wave optics and relativistic front description. II. The vector theory. Phys Rev A. 1983;28:2921–2932. doi: 10.1103/PhysRevA.28.2921, Paraxial-wave optics and relativistic front description. I. The scalar theory. Phys Rev A. 1983;28:2933–2942. doi: 10.1103/PhysRevA.28.2921). This paper extends that result to Maxwell fields, again emphasizing the central role of unitarity in defining the association. The principal new technical element in the present discussion has to do with the intertwining of polarization and spatial degrees of freedom in the resulting single-photon states.

DOI: 10.1080/09500340.2026.2626917

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