Quantum theory of a laser soliton

TL;DR

This paper develops a quantum electrodynamics framework for spatial laser solitons in wide-aperture lasers with saturable absorption, analyzing their quantum statistical features and potential for quantum squeezing.

Contribution

It introduces a quantum Heisenberg-Langevin equation for laser solitons, incorporating Langevin sources and adiabatic approximation, to study their quantum properties and squeezing potential.

Findings

Formulated a quantum model for laser solitons.

Analyzed quantum statistical features of solitons.

Discussed conditions for observing quantum squeezing.

Abstract

The Heisenberg-Langevin equation for a spatial laser soliton in a wide-aperture laser with saturable absorption is constructed within the framework of consistent quantum electrodynamics. We discuss in detail the canonical variables for the generation field and the material two-level medium, consisting of centres providing amplification and absorption. It is assumed that laser generation evolves in time much more slowly than an atomic media. This assumption makes it possible to apply the adiabatic approximation and construct a closed equation for the amplitude of a laser field. Much attention is paid to the formulation of Langevin sources when deriving the equation since they play a decisive role in the formation of solitons' quantum statistical features. To provide an appropriate procedure for observing the quantum squeezing of a soliton, synchronization of laser generation by an external weak electromagnetic field is considered. Here we also present the results of the analysis of a classical laser soliton (neglecting the quantum fluctuations), which serves as the basis for further consideration of quantum effects.