交变电场驱动下三量子点中双电子的动力学  

Dynamical Behaviors of Two Electrons Confined in a Line Shape Coupled Three Quantum Dots Driven by an AC Electric Field

作　　者：刘承师[1] 马本堃[1] 

机构地区：[1]北京师范大学物理系,北京100875

出　　处：《光学学报》2004年第5期700-704,共5页Acta Optica Sinica

基　　金：教育部博士点基金 (96 0 0 2 70 3)资助课题

摘　　要：采用三点哈巴德模型及弗洛盖定理 ,研究了交变电场驱动下线形三量子点分子中双电子的动力学行为。由于系统哈密顿量中不包含自旋反转项 ,所以系统单态和三重态子空间是完全解耦的 ,可以分开进行讨论。研究表明 ,自旋三重态九维子空间还可以进一步分解成三个不相耦合的子空间 ,在每一个子空间中 ,动力学行为与交变电场驱动的双量子点中双电子的动力学行为相似。对自旋单态 6维子空间 ,数值计算还表明 ,在合适的外加交变电场驱动下 ,电子在量子点之间的隧穿被抑制 ,初始局域在一个量子点中的两个电子能够在一定时间内保持其局域状态。With the three-site Hubbard model and Floquet theorem, the dynamical behaviors of two electrons confined in a line shape coupled three quantum dots driven by an AC electric field are investigated. The Hamiltonian contains no spin-flip terms, so the singlet and triplet sub-spaces are completely decoupled and can be analyzed separately. The analysis indicates that the nine-dimensional triplet sub-spaces can be divided intos three-dimensional sub-spaces with the same direction of spin respectively, and the dynamical behaviors in each three-dimensional sub-space are similar to that of two-electron singlet state in coupled two-quantum dots driven by AC electric field. In the six-dimensional spin singlet sub-space, the calculations show that, for certain combination of frequency and strength of applied AC field, the tunnelling between various configurations can be strongly quenched. Specially, two electrons localized initially in one quantum dot can hold on for a span of time. Using the perturbation approach to solve the Floquet function leads to a detailed understanding of this effect.

关 键 词：交变电场 弗洛盖态 量子点 动态局域化 局域态 哈密顿量 

分 类 号：O471.1[理学—半导体物理]