  Electronic Mach-Zehnder interferometers in the Quantum Hall (QH) regime are
currently discussed for the realization of quantum information schemes. A
recently proposed device architecture employs interference between two
co-propagating edge channels. Here we demonstrate the precise control of
individual edge-channel trajectories in quantum point contact devices in the QH
regime. The biased tip of an atomic force microscope is used as a moveable
local gate to pilot individual edge channels. Our results are discussed in
light of the implementation of multi-edge interferometers.

Mesoscale and Nanoscale Physics