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 =1/2 and on the low- side of the =1 QHE state, while edge-state conduction is observed near =3/2 and on the high- side of the =1 QHE state. We also observe that the electron-hole symmetry is broken for the edge states in a confined geometry.