  We argue that dynamics of gapless Fractional Quantum Hall Edge states is
essentially non-linear and that it features fractionally quantized solitons
propagating along the edge. Observation of solitons would be a direct evidence
of fractional charges. We show that the non-linear dynamics of the Laughlin's
FQH state is governed by the quantum Benjamin-Ono equation. Non-linear dynamics
of gapless edge states is determined by gapped modes in the bulk of FQH liquid.
The dispersion of edge modes is traced to the double boundary layer of FQH
states.
