Resonant suppression of the quantized Hall effect in ballistic junctions

We have fabricated a quantum dot with four leads attached via variable-width constrictions. At high magnetic fields and low temperatures, the h/2${\mathit{e}}^2$ and h/4${\mathit{e}}^2$ quantized Hall pleateaux observed for wide constrictions are replaced by a series of minima that go to zero or below as the constrictions are squeezed. These resonances are explained well by a recent model proposed by Kirczenow (following paper) to describe this structure, in which each lead transmits only one edge state. The minima can be explained by interference between edge states near the constrictions.