Interlevel electromagnetic response of quantum dots of shapes with uniaxial rotation symmetry

Abstract

Within the density response and density matrix formalisms, employing the self-consistent field approach in the quasistatic limit it is considered the interlevel infrared electromagnetic response of individual infinite deep quantum dots ͑QDs͒ as well as of two-dimensional infinite square lattices of the identical QDs of different shapes with uniaxial rotation symmetry: semispherical, lens, slightly ellipsoidal, and cylindrical. It is shown that the QD shape can critically affect the interlevel optical properties of the considered QD systems, in particular, the dependence of the QD polarizability upon the polarization of the incident radiation. To facilitate consideration of the dipole coupled interlevel transitions and of the formation of ͑interacting͒ modes of the electron interlevel collective excitation, and calculation of the absorption spectra for the QDs, illustrative maps of the transitions are utilized and the concept of the "m family" for the eigenstates is found to be fruitful, where m is the magnetic quantum number labeling the eigenstates of the QDs. It is shown that the shape and size of QDs can impact the depolarization effect considerably. Numerical calculations show that the dipole-dipole interaction approximation very well describes the depolarization shift caused by the interdot electron-electron interaction for each of the considered QD shapes and for any reasonable values of the size parameters of the lattices.

Effect of Electron–Electron Interaction on Nonlinear Near-Resonance Electromagnetic Response of Quantum Dot Systems

“…1 The only physical quantity which is affected by the self-interaction is ðṼ 2121 ½Dq 12 ðI; xÞÞ: More precisely, ðṼ 2121 ½Dq 12 ðI; xÞÞ includes the selfinteraction contribution, which should be eliminated by taking into account the configuration of the states and transitions and number of electrons in a QD. 1,2 In the following, we consider a two-state electron system with one electron per QD. In this case Dq ð0Þ 12 ¼ 1 and to eliminate the self-interaction contribution the required modification is as V 2121 ½Dq 12 ðI; xÞ !Ṽ 2121 ½Dq 12 ðI; xÞ; whereṼ 2121 1 V 2121 ÀL 2121 andL 2121 ¼ 2L 2121 E 21 ; and L 2121 represents the self-interaction contribution.…”

“…The manybody interaction not only affects essentially the electromagnetic response of QD systems but it also determines, forms, and governs many fundamental optical properties of QD systems (see, e.g., Refs. [1][2][3]. In this work we considered some nonlinear optical features of QDs resulted from the many-body effects, which could be a basis for designing nano-optoelectronic devices.…”

Anisotropic exciton Stark shift in hemispherical quantum dots

“…[1][2][3][4][5][6][7] With nanostructure sizes decreasing, the geometrical shapes of nanostructures become more and more important because they significantly modify the electronic structures and modulate other physical properties. [8][9][10] Since the spherical symmetry is broken, HQDs are able to control many properties of macroscopic materials by means of quantum-mechanical effects. They provide a threedimensional carrier confinement resulting in the superior carrier localization and optical confinement capabilities.…”