Influence of microwave fields on electron transport through a quantum dot in the presence of direct tunneling between leads

Abstract

We consider the time-dependent electron transport through a quantum dot coupled to two leads in the presence of the additional over-dot (bridge) tunneling channel. By using the evolution operator method together with the wide-band limit approximation we derived the analytical formulaes for the quantum dot charge and current flowing in the system. The influence of the external microwave field on the time-average quantum dot charge, the current and the derivatives of the average current with respect to the gate and source-drain voltages has been investigated for a wide range of parameters.

Charging time effects and transient current beats in horizontal and vertical quantum dot systems

“…In such systems many interesting effects have been predicted and observed e.g. photon-assisted tunnelling, electron pumping or excited states transport [15][16][17][18][19]. The propagation of sinusoidal or train-like pulses through a quantum wire can also lead to charge or spin pumping [20][21][22].…”

Mono-parametric charge pumping through a quantum dot coupled with energy-gapped leads

“…The time evolution of the QD charge and the current flowing between leads and the dot is described in terms of the time-evolution operator U (t, t 0 ) given (in the interaction representation) by the equation ( = 1) [39,40,42]:…”

“…[39][40][41][42]. The problem we study here is relatively complex because we consider the time-dependent transport through the system with energy-gapped band structure of the leads.…”

“…In the case when the lead's DOS varies slowly with energy (in the vicinity of the levels of the central scattering region) a wide band approximation (WBL) can be used with the energyindependent spectral density function [43]. This procedure drastically simplifies mathematical derivations which often leads to analytical formulas for the current or QD charge in the stationary as well as time-dependent processes [24,40,[42][43][44]. However, electron reservoirs are often characterized by complex band structures which need nontrivial calculations beyond the WBL approximation especially for time-dependent forces acting on the system, e.g.…”

Spin-Dependent Transient Effects in Electron Transport in the Quantum Dot System

“…[1][2][3][4]). However, in the context of emerging field of spintronic or recent experimental advances in the studies of the QD subjected to ultrafast voltage pulses, it would be desirable to perform the time-dependent simulations of the charge and spin dynamics also in a transient timescale when some QD system parameters were suddenly changed.…”