Shifting a Quantum Wire through a Disordered Crystal: Observation of Conductance Fluctuations in Real Space

A quantum wire is spatially displaced by suitable electric fields with respect to the scattering potentials inside a semiconductor crystal. As a function of the wire position, the low-temperature conductance shows reproducible fluctuations. Their characteristic temperature scale is a few hundred millikelvin, indicating a phase-coherent effect. One fluctuation is attributed to a single bump in the scattering potential entering or leaving the wire.