色散和杂质对双参量非对称高斯势量子点量子比特的影响  

Influence of dispersion and impurity on double-parameter asymmetric Gaussian quantum dot qubit

作　　者：乌云其木格[1] 韩超[2] 额尔敦朝鲁[2] Wuyunqimuge;Han Chao;Eerdunchaolu(College of Physics and Electronic Information,Inner Mongolia University for Nationalities,Tongliao 028043,China;Institute of Condensed Matter Physics,Hebei Normal University of Science and Technology,Qinhuangdao 066004,China)

机构地区：[1]内蒙古民族大学物理与电子信息学院,通辽028043 [2]河北科技师范学院凝聚态物理研究所,秦皇岛066004

出　　处：《物理学报》2019年第24期322-328,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51902085);内蒙古自治区自然科学基金(批准号:2019MS01011)资助的课题~~

摘　　要：选取双参量非对称高斯势描写量子点中电子的受限效应,采用LLP-Pekar变换变分法研究了色散和杂质对量子点量子比特性质的影响.结果表明,量子点量子比特中电子的概率密度随非对称高斯势阱宽的减小而呈现显著振荡,并随介电常数比的增加而减小;量子比特振动周期随高斯势阱深的增加或介电常数比的增加而减小;退相干时间随介电常数比的增加或色散系数的增加而增大;相位旋转品质因子随介电常数比的增加或色散系数的增加而增大.Selecting the double-parameter asymmetric Gaussian(AG)potential to describe the confinement effect of electrons in a quantum dot,the ground state and the first excited state energy eigenvalues and eigenfunctions of the three-body interaction system that are composed of the electrons,the impurity and the longitudinal optical phonon are derived by using the Lee-Low-Pines unitary transformation and the Pekar-type variational method,and the two-level structure required for a qubit is constructed.The influences of material parameters such as the dispersion coefficient,dielectric constant(DC)ratio,and electron-phonon coupling(EPC)constant on the probability density and the oscillation period of electron in the AG potential qubit are investigated.Based on the Fermi gold rule and the even-order approximation,the effects of the DC ratio,the dispersion coefficient and the EPC constant on the qubit decoherence are studied.And then the influences of the dispersion coefficient,the DC ratio and the EPC constant on the phase rotation manipulation of the qubit sphere are discussed.Numerical results show that the dispersion coefficient,the DC ratio and EPC constant of the medium have both advantages and disadvantages for the formation and information storage of qubits.The probability density of electrons in quantum dot qubits decreases with DC ratio increasing and exhibits significant oscillations as the well width of the AG potential decreases;the oscillation period of the qubit decreases with the well depth of the AG potential or the DC ratio increasing;the decoherence time increases with DC ratio or dispersion coefficient increasing;the phase rotation quality factor increases with DC ratio or dispersion coefficient increasing.Using the double-parameter AG potential to describe the confinement of electrons in quantum dot will better reflect the quantization properties of qubit.Increasing the dispersion coefficient or the DC ratio of the material is beneficial to not only the phase rotation manipulation of the qubit sphere,but a

关 键 词：量子比特 非对称高斯势 概率密度 振动周期 退相干时间 相位旋转品质因子 

分 类 号：TN9[电子电信—信息与通信工程]