摘要
利用二能级近似理论分析了外场驱动下非对称耦合双量子点中激子的动力学行为,并给出了局域化的条件.分析发现:当外场振幅较小时,库仑相互作用扮演着重要角色,激子的动力学行为主要发生在低能级子空间,场强和频率之比是Bessel方程的根时,准能发生回避交叉,激子的局域化现象发生.随着外场振幅增大,激子解体,电子和空穴可以独立在量子点之间隧穿.借助于Floquet理论,进行了数值计算,计算结果与理论分析相符.
Dynamics of an exciton in asymmetric double coupled quantum dots with an ac-electric field are analyzed based on the two-level systems theory,and the conditions in which dynamical localization occurs is determined.Theoretical analysis shows that when the amplitude of the ac-field is small,the Coulomb interaction plays an important role and the electron and hole can’t be divided.The dynamics of the exciton are mainly confined in a low-energy subspace.When the ratio of the amplitude and frequency is the root of the Bessel function,the electron and hole are localized in one dot.But when the amplitude of the ac-field is much larger,the electron and hole can be divided.The numerical results,based on Floquet theory,agree well with the theoretical analysis.
