Evaluation of electron-electron interactions in coupled quantum dots by using far-infrared spectra

We have studied the far-infrared spectra of two-electron vertically coupled quantum dots in an axial magnetic field by exact diagonalization. The calculated results show an obvious difference in role between the interactions for spin S = 1 and for spin S = O. The results support the possibility to evaluate the interactions by far-infrared spectroscopy in vertically coupled quantum dots.

Single Photon Scattering in a Pair of Waveguides Coupled by a Whispering-Gallery Resonator Interacting with a Semiconductor Quantum Dot

The single photon scattering properties in a pair of waveguides coupled by a whispering-gallery resonator in- teracting with a semiconductor quantum dot are investigated theoretically. The two waveguides support four possible ports for an incident single photon. The quantum dot is considered a V-type system. The incident direction-dependent single photon scattering properties are studied and equal-output probability from the four ports for a single photon incident is discussed. The influences of backscattering between the two modes of the whispering-gallery resonator for incident direction-dependent single photon scattering properties are also pre- sented.

Three-Electron Quantum Dots in Zero Magnetic Field

By using the exact diagonalization method,a system of three electrons confined in a parabolic quantumdot in zero magnetic field is studied.The ground-state electronic structures and orbital and spin angular momentatransitions as a function of the confined strength are investigated.We find that the confinement may cause accidentaldegeneracies between levels with different low-lying states and the inversion of the energy values.The present,resultsare useful to understanding the optical properties and internal electron-electron correlations of quantum dot materials.

The energy levels of a two-electron two-dimensional parabolic quantum dot

This paper studies the two-electron total energy and the energy of the electron-electron interaction by using a variational method of Pekar type on the condition of electric-LO-phonon strong coupling in a parabolic quantum dot. It considers the following three cases： 1） two electrons are in the ground state; 2） one electron is in the ground state, the other is in the first-excited state; 3） two electrons are in the first-excited state. The relations of the two-electron total energy and the energy of the electron-electron interaction on the Coulomb binding parameter, the electron-LO-phonon coupling constant and the confinement length of the quantum dot are derived in the three cases.

Dispersion Theory of Polaron in a Parabolic Quantum Dot at Finite Temperatures

By using the dispersion theory instead of the Frhlich Hamiltonian,the polaron energy in a quantum dot with a parabolic confinement potential is investigated at finite temperatures.It is found that the self-trapping energy of the polaron decreases with the increasing temperature,and the temperature effect is more obvious in quantum dots with weaker confinement.

Ground State Transitions of Four-Electron Quantum Dots in Zero Magnetic Field

<Abstract>In this paper,we study four electrons confined in a parabolic quantum dot in the absence of magnetic field,by the exact diagonalization method.The ground-state electronic structures and orbital and spin angular momenta transitions as a function of the confined strength are investigated.We find that the confinement may cause accidental degeneracies between levels with different low-lying states and the inversion of the energy values.The present results are useful to understand the optical properties and internal electron-electron correlations of quantum dot materials.

Influence of temperature and LO phonon on the effective mass of bipolarons in polar semiconductor quantum dots

The temperature and LO phonon effects of the bipolaron in polar semiconductor quantum dots(QDs)are studied by using the Tokuda modified linear-combination operator method and the Lee-Low-Pines variational method.The expressions for the mean number of LO phonons and the effective mass of the bipolaron are derived.Numerical results show that the mean number of LO phonons of the bipolaron decreases with increasing the temperature and the relative distance r between two electrons,but increases with increasing the electron-phonon coupling strengthα.The effective mass of the bipolaron M* increases rapidly with increasing the relative distance r between two electrons when r is smaller,and it reaches a maximum at r≈4.05r p,while after that,M*decreases slowly with increasing r.The effective mass of the bipolaron M*decreases with increasing the temperature.The electron-phonon coupling strengthαmarkedly influences the changes of mean number of LO phonons and the effective mass M*with the relative distance r and the temperature parameter γ.

A Two-Electron Quantum Ring Under Magnetic Fields

我们在垂直同类的磁场的影响下面计算一枚二电子的量戒指的低状态的精力层次。计算被在有效团的近似以内使用准确 diagonalization 的方法做。地面状态电子结构和尖动量转变作为一个磁场的力量的功能被揭示了。

声子之间相互作用对半导体量子点中磁极化子性质的影响

研究了半导体量子点中磁极化子的性质.采用线性组合算符和微扰法,导出了半导体量子点中磁极化子的基态能量.在计及电子在反冲效应中发射和吸收不同波矢的声子之间相互作用时,讨论了对半导体量子点中磁极化子的基态能量的影响.通过数值计算表明,半导体量子点中磁极化子的基态能量随量子点的有效受限长度的减小而迅速增大,随磁场的增加而增加,对于弱磁场声子之间相互作用的影响不能忽略.

D^-中心量子点的极化子效应(英文)

利用少体物理的方法 ,研究了半导体量子点中负施主杂质低激发态能谱的极化子效应 ,发现随着量子点的尺寸改变 ,有和没有电—声相互作用的影响 ,其能级顺序的改变是不一样的 .另一方面 ,我们计算了负施主杂质中心的基本束缚能随量子点半径的变化关系 。

Rashba效应影响下InAs/GaAs自组织量子点中极化子性质

考虑Rashab自旋—轨道相互作用对半导体量子点中极化子基态能量的影响.采用LLP中耦合的方法处理了电子—声子相互作用.结果表明由于Rashba效应的影响使得极化子的基态能量分列为上下两支而且Rashba自旋—轨道相互作用能与总的基态能及其它能量成分间的比例关系,随电子波矢K变化非常显著.Rashba自旋—轨道相互用作使得量子点中极化子基态能量在无任何外磁场的情况下发生分裂,所以完全不同于强磁场影响下的简单Zeeman效应,然而,自旋—轨道相互作用引起的分裂有时掺杂着Zeeman分裂,因此它引起的分裂属于复杂分裂.声子对总能量的贡献为负,由于声子的存在极化子争裂能较裸电子更为稳定.

Woods-Saxon限制势两电子量子点的自旋单态—三重态跃迁(英文)

使用Woods-Saxon限制势,研究了磁场对二维两电子量子点系统的影响,研究方法的优点是在模型位阱中可以通过两个参数改变限制范围。计算是在有效质量近似框架下采用矩阵对角化方法进行,发现了一个基态行为(自旋单态—三重态跃迁)作为磁场强度的函数。此外还发现Woods-Saxon限制垒的位置和斜率对二维两电子量子点系统的基态跃迁和低激发态性质是重要的。

Rashba效应影响下半导体量子点中弱耦合极化子的性质

采用改进的线性组合算符和幺正变换的方法研究Rashba效应影响下量子点中弱耦合极化子的性质.导出了Rashba效应影响下量子点中弱耦合极化子的振动频率、有效质量、基态分裂能和相互作用能.数值计算结果表明表明随Rashba自旋-轨道耦合常数α_R的增加由于声子作用产生的附加能量能对零磁场下自旋分裂能的影响占有绝对优势.所以,研究Rashba自旋轨道相互作时声子的影响不可忽略.

磁场内双声子作用对量子点中极化子的影响

为突出双声子相互作用对磁场内量子点中极化子的影响,简化了理论模型,把库仑势对电子质量的影响用电子在能带中的质量来代替。使用线性组合算符和么正变换对系统进行理论计算,导出了半导体量子点中磁极化子的基态和各部分能量。当考虑电子在反冲效应中反射和吸收不同波矢的声子之间相互作用时,讨论了这种作用对半导体量子点中磁极化子基态能量的影响。通过数值计算表明,半导体量子点中磁极化子的基态能量随量子点的有效受限长度的减小而迅速增大,随磁场的增加而增加。当磁场较弱时,声子之间的相互作用对极化子性质的影响是不能忽略的。