DEMONSTRATION OF DEVICE CONDUCTANCE MODULATION BY ELECTROSTATIC CONTROL OF THE ELECTRON PHASE

In this paper we describe a novel effect observed in a quantum wire co ntaining two parallel ''artificial'' (i.e., electrostatically defined antidots) impurities. At low magnetic fields we observe a series of re sistance peaks. These occur at magnetic fields for which classical ele ctron trajectories are commensurate with the device geometry. The resi stance peaks are modulated by periodic oscillations that can be observ ed both as a function of the applied magnetic field or the gate voltag e, which controls the size of the impurities. These oscillations are a nalyzed in terms of the classical action of ballistic electrons on clo sed trajectories, the related phase gained along these trajectories, a nd the resulting quantum interference effect. We show that these oscil lations when observed as a function of gate voltage are consistent wit h changes of the electron wavelength along part of the electron trajec tory. The device conductance is thus being modulated by the electrosta tic control of the electron phase.