Evidence for saturation of channel transmission from conductance   fluctuations in atomic-size point contacts
  The conductance of atomic size contacts has a small, random, voltage dependent component analogous to conductance fluctuations observed in diffusive wires (UCF). A new effect is observed in gold contacts, consisting of a marked suppression of these fluctuations when the conductance of the contact is close to integer multiples of the conductance quantum. Using a model based on the Landauer-Buettiker formalism we interpret this effect as evidence that the conductance tends to be built up from fully transmitted (i.e., saturated) channels plus a single, which is partially transmitted. 
B. Ludoph, M.H. Devoret, D. Esteve, C. Urbina and J.M. van Ruitenbeek