Nonlinear conductance of a quantum point contact
= Nonlinear conductance of a quantum point contact
{title2=$dI/dV=(e^2/h)\sum_n[T_n(\mu_S)+T_n(\mu_D)]$}
At zero <temperature>, a rigid spin-degenerate transmission spectrum with symmetric source/drain bias has $\mu_{S,D}=E_F\pm eV/2$ and the displayed differential conductance. Half-integer plateaus in units $2e^2/h$ occur when the two bias-window edges sample different channel counts. The bias convention and electrostatic response matter.