EDGE STATES IN THE FRACTIONAL QUANTUM HALL-EFFECT

We have studied nonlocal electrical transport over macroscopic distances in the regime of the fractional quantum Hall effect (FQHE). Experiments clearly demonstrate dissipationless edge-state conduction associated with the FQHE. Surprisingly, our data imply that there is no edge-state conduction near filling factor-nu = 1/2 and on the low-nu-side of the nu = 1 QHE state, while edge-state conduction is observed near nu = 3/2 and on the high-nu-side of the nu = 1 QHE state. We also observe that the electron-hole symmetry is broken for the edge states in a confined geometry.