Resistance fluctuations in narrow AlGaAs/GaAs heterostructures: Direct evidence of fractional charge in the fractional quantum hall effect

In 2-m-wide Hall bars of high-mobility GaAs/AlGaAs heterostructure resistance fluctuations of quasiperiod "B0.016 T are observed near the diagonal resistance minima for Landau-level filling factors =1,2,3,4. This behavior is consistent with resonant reflection through magnetically bound states as a mechanism for the breakdown of dissipationless transport in narrow channels. In the =(1/3 minimum of the fractional quantum Hall effect we observe similar fluctuation structure, but with a period of 0.05 T3"B, indicative of transport by quasiparticles of fractional charge e/3.