Soliton-like unipolar objects in nonequilibrium dissipative media

Abstract

For electromagnetic pulses without a carrier frequency, propagating in a system of multilevel atoms with a fast irreversible relaxation of the induced dipole moment, but a slow relaxation of the populations of quantum states, the nonlinear integro-differential equations of the ‘reaction–diffusion’ type are derived. One-dimensional soliton-like solutions of these equations in the form of unipolar pulses are found and analyzed. It is shown that such pulses can be formed in a nonequilibrium medium. These pulses transfer a medium to other metastable states, which depend on the input conditions. The propagation of these soliton-like signals is accompanied by a change in the populations of quantum states of atoms in the modes of switching waves with the memory of input conditions.