Electron interferometer in the integer QH regime

We report experiments on an electron interferometer fabricated from high mobility, low density GaAs/AlGaAs heterostructure material. In this device, a nearly circular electron island is separated from the 2DES by two nearly open constrictions. In the integer QH regime $f$ = 1 and 2, we observe Aharonov-Bohm-like oscillations of conductance. The interference closed path is comprised by the two edge states circling the island, coupled by tunneling in the constrictions, the radius $r \sim $ 900 nm is determined from the oscillation period. The radius can be tuned by application of a bias V$_{FG}$ to the four front gates. We find approximately linear dependence d$r$/dV$_{FG }$= 0.25 nm/mV. We compare the experimental results to the island B = 0 electron density profile obtained in classical electrostatic models of Gelfand and Halperin, PRB \textbf{49}, 1862 (1994) and Chklovskii el al., PRB \textbf{46}, 4026 (1992).