Finite-Frequency Shot Noise Of Electron Through A Serially Coupled Double Quantum Dot System With Effective Spin-Orbit Coupling Field

The finite-frequency shot noise of electron transport through single molecule devices has become a powerful diagnostic tool for characterizing electron transport characteristics because it can extract the information about the transport time scales associated with the internal energy structures of the single molecule devices and probe the internal dynamics of the single molecule devices which cannot be obtained through the average current and the zero-frequency shot noise.In addition,the quantum dot system has become a candidate quantum system for implementing spintronics due to the tunability of its experimental parameters.Here,how to manipulate and detect the spin degree of freedom based on the spin-orbit coupling(SOC)effect have received much attention and have been studied extensively.Therefore,the influence of the spin-orbit coupling effect on the electron transport properties of electron transport through coupled quantum dot systems has become an important and promising research field in condensed matter physics.However,most of the previous investigations on quantum transport in QD systems with SOC or spin-flip scattering were focused mainly on the average current19–21 or the zero-frequency shot noise.Although the influence of the magnitude of the spin-flip scattering on the finite-frequency shot noise in a single QD have already been studied,the dependence of the finite-frequency shot noise on the internal energy structures of coupled QD systems and the spin polarization of the two electrodes has not yet been revealed,which requires further studies.Especially,in coupled QD systems,extracting quantitatively the magnitude of the spin-orbit coupling through the finite-frequency shot noise is still an open issue.In this paper,based on an effective particle-number-resolved quantum master equation,we study the influences of the magnitude of the SOC,the magnitude of the external magnetic field,the energy-level detuning and the spin polarization rates of the two electrodes on the finite frequency shot noise of electron transport through the serially coupled double QD system with SOC weakly coupled to two ferromagnetic electrodes,and discuss the feasibility of extracting quantitatively the magnitude of the SOC through the finite-frequency shot noise.We demonstrate that the finite-frequency shot noise displays an obvious dip,and the dip position,which is determined by the energy difference between the coherent singly-occupied eigenstates of the quantum dot system.In particular,the spin polarizations of the source and drain electrodes determine the width of the dip of the finite-frequency shot noise but have no influence on the position of the dip.These results suggest that the dip position of the finite frequency shot noise can be used to quantitatively extract the information about the energy difference between the coherent singly-occupied eigenstates and the magnitude of Rashba spin-orbit coupling.The predicted properties of the finite-frequency shot noise are of particular interest for understanding of the internal dynamics of the coupled quantum dot systems.