Fano factor reduction on the 0.7 structure in a ballistic one-dimensional wire

We have measured the non-equilibrium current noise in a ballistic one-dimensional wire which exhibits an additional conductance plateau at $0.7\times2e^2/h$. The Fano factor shows a clear reduction on the 0.7 structure, and eventually vanishes upon applying a strong parallel magnetic field. These results provide experimental evidence that the 0.7 structure is associated with two conduction channels which have different transmission probabilities.