Abstract
Every conductance measurement on metallic systems is affected to some degree by random quantum interference arising from the particular disordered microscopic arrangement of the electron scatterers. We have measured the conductance variations of submicron inversion layer segments in silicon MOSFETs, systematically changing the length, width, inelastic diffusion length, gate voltage, magnetic field and temperature. The statistical properties of the observed conductance variations agree quantitatively with the theory of universal conductance fluctuations, demonstrating that random quantum interference causes rms conductance changes of magnitude e2/h in each phase-coherent subunit of each conducting segment. In small, narrow devices, the fractional conductance variations are of order unity, resulting in large resistance changes. By studying the effects of trapping single electrons at individual interference traps, we demonstrate that the random quantum interference can be extremely sensitive to changing a single scatterer.