Universal conductance fluctuations
= Universal conductance fluctuations
{title2=$\delta G\sim e^2/h$}
A coherent disordered mesoscopic conductor has reproducible, sample-dependent conductance variations when magnetic field, carrier energy or disorder configuration changes. Their typical scale is of order $e^2/h$ in a fully coherent diffusive sample, with numerical factors determined by symmetry, dimensionality and geometry. Thermal averaging and finite <phase coherence length> reduce the measured amplitude.