Evidence for non-linear quasiparticle tunneling between fractional quantum Hall edges

Remarkable nonlinearities in the differential tunneling conductance between fractional quantum Hall edge states at a constriction are observed in the weak-backscattering regime. In the $\nu $ = 1/3 state a peak develops as temperature is increased and its width is determined by the fractional charge. In the range $2/3 \le \nu \le 1/3$ this width displays a symmetric behavior around $\nu $ = 1/2. We discuss the consistency of these results with available theoretical predictions for inter-edge quasiparticle tunneling in the weak-backscattering regime.