Time-dependent resonant tunneling transport: Keldysh and Kadanoff-Baym nonequilibrium Green's functions in an analytically soluble problem

摘要

Here we address two nonequilibrium Green's functions approaches for aresonant tunneling structure under a sudden switch of a bias. Our aim is tostress that the time-dependent Keldysh formulation of Jauho, Wingreen and Meir,and the partition-free scheme of Stefanucci and Almbladh are formallyequivalent in the ubiquitous case of wide-band limit and noninteractingelectrons, if leads and dot are in equilibrium before the time-dependentperturbation. We develop explicit closed formulas of the lesser Green'sfunction and time-dependent current, reminding that the different integrationlimits preclude a face-to-face comparison of two approaches. This study shedslight on both practices, which are of great interest to the mesoscopictransport community.