Study On Quantum Transport Of Time-dependent Quantum Dot System

The quantum transport of electrons passing through mesoscopic systems has been an active research area.The electron transport theory and the preparation of nanodevices have been widely used,providing an important foundation for designing and improving the characteristic of quantum setup.With the accuracy requirements for devices are getting higher and higher,a variety of factors that have an impact on transport properties more and more attention has been paid,in particular,small changes in the material interface structure over time have effect on the transport properties of the system.In this paper,we consider the structural changes in the quantum dots and electrode interface,to study the quantum transport properties of quantum dot systems.Firstly,we introduce a theoretical method based on the non-equilibrium Green’s function to solve the transport problem of the time-dependent system.It uses the difference in scale between electronic tuning and interface oscillation to separate the time into central time and relative time,we expand Kadanoff-Baym equation in the Wigner space according to the derivative gradient of the central time,and then obtain the expression about the central time derivative of retarded(advance,less)Green’s function.Next,we consider the oscillation of the coupling interface between quantum dot and electrode to study the transport properties of the parallel double quantum dot AB ring.Assuming that the tunneling amplitudes between the quantum dot and the electrode have a linear dependence on the amplitude of the interface oscillation,the research results show that the interface oscillation will cause a correction term for the conductance of the quantum dot system when the oscillation is not considered.As the change of the linear coupling parameter between the coupling strength and the oscillation amplitude,the resonance peak of the conductance changes from one to two with the change of the quantum dot energy.The coupling between two quantum dots can cause the position of the resonant peak of conductance to change,and the extent of change is related to the magnitude of the coupling strength.Two magnetic fluxes of equal magnitude and opposite directions are applied to the two AB sub-rings,change the size of the magnetic flux,when the phase caused by the magnetic flux is not equal toπ/ 2 integer multiple,the zero-order conductance will have the Fano effect,and the correction term will also enhance this effect,greatly changing the transport performance of the system.