  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.
