Research On Transport Properties And Quantum Computing Based On HgTe Quantum Dots

In recent years,the size of integrated circuits has entered the mesoscopic size standard,and various physical effects can hinder the progress and development of integrated circuits,thereby constraining Moore’s law.Therefore,in order to continue and expand integrated circuits,optimization of device materials for integrated circuits can be considered.Hg Te topological insulator quantum dot is a new type of material with internal insulation and surface conductivity,and there are edge states with opposite spin,so it has the potential to form devices.Therefore,this article investigates the current transport of small-sized Hg Te quantum dots between ferromagnetic electrodes;Meanwhile,due to the presence of several ferromagnetic electrodes with gate voltage around the Hg Te quantum dot qbit,it is difficult to place other double Hg Te quantum dot qbits next to one Hg Te quantum dot qbit.Therefore,this article proposes a theoretically feasible multi Hg Te quantum dot qbit programmable manipulation coupling scheme.The specific research content and contributions are as follows:(1)Firstly,the energy band and electronic density of states functions of small-sized Hg Te quantum dots are derived.Then,the energy band and electronic density of states diagrams are drawn based on this function to understand the distribution of edge state electrons in quantum dots and compare them with traditional quantum dots.Then,the current formula of Hg Te topological insulator quantum dot between two ferromagnetic electrodes is derived by using the non-equilibrium Green’s function method.Based on the current formula,the effects of quantum dot thickness,temperature and defects on the transport current are studied.The experimental results indicate that due to the energy band of the edge states of small-sized Hg Te quantum dots located within the bulk state bandgap,current will be generated under small bias,resulting in better transport performance of Hg Te quantum dots compared to traditional semiconductor quantum dots.At the same time,the transport conductivity decreases as the thickness of the quantum dot increases,the temperature increases,and the defect increases.(2)The specific method of realizing qbit with Hg Te quantum dot structure is introduced,including Hamiltonian form of electronic qbit and spin qbit,physical realization,manipulation method,etc.The coupling systems of several Hg Te quantum dots,as well as the coupling effects: repulsion and exchange,are also analyzed.At the same time,a simple multi qbit programmable manipulation coupling path is proposed,it solves the problem that a single quantum dot qbit cannot couple multiple adjacent quantum dot qbits at the same time.Figure [14] Table [1] Reference [45]...