  In the framework of quantum field theory we discuss the emergence of a phase
locking among the electromagnetic modes and the matter components on an
extended space-time region. We discuss the formation of extended domains
exhibiting in their fundamental states non-vanishing order parameters, whose
existence is not included in the Lagrangian. Our discussion is motivated by the
interest in the study of the general problem of the stability of mesoscopic and
macroscopic complex systems arising from fluctuating quantum components in
connection with the problem of defect formation during the process of
non-equilibrium symmetry breaking phase transitions characterized by an order
parameter.
