Weakly nonlinear ac response: theory and application

Abstract

We report a microscopic and general theoretical formalism for electrical response, which is appropriate for both dc and ac weakly nonlinear quantum transport. The formalism emphasizes the fundamental requirements of current conservation and gauge invariance. It makes a formal connection between linear response and scattering matrix theory at the weakly nonlinear level. We present three examples of application of this formalism to analyze the dynamic conductance and the nonlinear-nonequilibrium charge distribution for multiprobe coherent quantum conductors. © 1999 The American Physical Society.