Dynamical properties of two-band superlattices with strong interband coupling in real space under the action of ac and dc－ac fields

Within a two-band tight-binding model driven by ac and dc－ac electric fields, using numerical methods, we investigate the dynamics of electrons and the quasi-energy spectrum of the system with strong interband coupling in real space. We find that when the bandwidth is suppressed to a value much smaller than the field frequency, the dynamical localization can exist in the system. The corresponding regions are found for the occurrence of dynamical localization in the parameter space.     

交变电场驱动下耦合双量子点中激子的动力学行为

利用两点Hubbard模型和Floquet定理，研究了交变电场驱动下耦合双量子点中激子的动力学行为.计算结果表明，系统准能级随交变电场振幅的变化出现一系列严格交叉和回避交叉.在最低的两个准能级的第一个严格交叉点处，初始局域状态一般能够保持，并且随着点内的电子空穴之间库仑相互作用的增强，动态局域化的程度会提高.在最低的两个准能级的第二和第三个严格交叉点处，随着交变电场的增强，这种动态局域化被破坏.在偏离准能严格交叉点和回避交叉点，则不能存在动态局域化现象. 关键词： Floquet态 准能 局域态     

方波电场驱动下的Rabi振荡

研究了方波电场驱动下的双Bloch带的紧束缚模型.借助Fourier分析,得到了在弱耦合极限下Rabi振荡及Rabi频率的解析解;这些结果均由电子的数值演化所证实.     

Transport characteristics of Rabi oscillations in the two-band superlattices

We investigated the transport characteristics of Rabi oscillations, by using numerical methods, within a two-band tight-binding model driven by dc－ac electric fields. We found that Rabi oscillations make the long-time average current a sharply change, i.e. the current have resonant peaks appearing. Rabi oscillations are destroyed by dephasing; these peaks are the signatures of Rabi oscillations on the current response. The strong interband coupling will change the conditions of Rabi oscillations and, correspondingly, changes the places where the current resonant peaks appear.     

交变电场驱动下三量子点中双电子的动力学

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。     

在强交变电场驱动下线形三量子点分子中激子的动态局域化行为

采用三点Hubbard模型和Floquet定理，研究了在强交变电场驱动下线形三量子点分子中激子的动力学行为.数值计算表明，尽管驱动电场倾向使电子和空穴在空间上分离，但在合适的 外电场驱动下，初始局域在一个量子点中的电子和空穴依旧保持其初始局域状态.应用微扰 理论求解Floquet方程，从而得到准能的解析解.表明在准能级发生交叉点，激子可呈现出动 态局域化. 关键词： Floquet态 准能 局域态 动态局域化     

Effects of bias on dynamics of an AC-driven two-electron quantum-dot molecule

The effects of bias on the dynamical localization of two interacting electrons in a pair of coupled quantum dots driven by external AC fields have been numerically investigated. With an effective two-site model and Floquet formalism,the time-dependent Schroedinger equation is numerically solved and the Pmin, the minimum of the population evolution of the initial state within a certain time period, is used to quantify the degree of the dynamical localization. Results indicate that the bias can change the energy of the initial state and break the dynamical symmetry of the system with a pure AC field. And the amplitude of the AC field with dynamical localization phenomenon changes with bias. All the numerical results are explained by the perturbation theory and two-level approximation.     

Quantization of nonintegrable maps

Using Heisenberg's matrix formulation of quantum mechanics, a method is given for quantizing volume-preserving polynomial mappings. The energy levels of the linear map are obtained exactly and those of the cubic, nonintegrable map are obtained approximately and numerically.     

Dynamic Behavior and Quasi—energy Spectrum of Multiband Superlattice Bloch Electrons in Quantum Kicked Potential

In this paper,we study the dynamic behavior and quasi-energy spectrum of multiband superlattics Bloch electrons in quantum kicked potential.We show analytically and numerically the avoided crossing and band suppression about the quasi-energy spectrum.The dynamic nonlocalization,and the electron oscillation behavior between two bands.