Encouraged by the latest experimental developments as well as by the theoretical interest on the near‐field (NF) optics of semiconductor quantum dots (QDs), we present our most recent theoretical results on the NF optical absorption and photoluminescence (PL) of single and coupled III‐V QDs subjected additionally to an external magnetic field of variable orientation and magnitude. The zero‐magnetic‐field “structural” QD symmetry can be destroyed varying the magnetic field orientation. The asymmetry induced by the magnetic field ‐except for specific orientations along symmetry axes‐ can be uncovered in the near‐field but not in the far‐field spectra. Hence, we predict that NF magnetoabsorption experiments, of realistic spatial resolution, will be in the position to bring to light the QD symmetry.

We examine the intersubband transition dynamics of a single semiconductor quantum well when the ground and the first excited subbands are coupled by strong electromagnetic fields, with emphasis given to controlled intersubband population inversion. The system dynamics is described by the nonlinear density matrix equations that include the effects of electron‐electron interactions. We present analytical results for the electromagnetic field that can lead to high‐efficiency population inversion in the system. The validity of the analytical results is tested with numerical solutions of the density matrix equations for various values of the electron sheet density for a realistic GaAs/AlGaAs quantum well.

We develop a fully quantum-mechanical theory for the interaction of light and electron–hole excitations in semiconductor quantum dots. Our theoretical analysis results in an expression for the photoluminescence intensity of quantum dots in the linear regime. Taking into account the single-particle Hamiltonian, the free-photon Hamiltonian, the electron–hole interaction Hamiltonian, and the interaction of carriers with light, and applying the Heisenberg equation of motion to the photon number expectation values, to the carrier distribution functions and to the correlation term between the photon generation (destruction) and electron–hole pair, we obtain a set of luminescence equations. Under quasi-equilibrium conditions, these equations become a closed-set of equations. We solve them analytically, in the linear regime, and we find an approximate solution of the incoherent photoluminescence intensity. The validity of the theoretical analysis is tested by investigating the emission spectra in the high-temperature regime, interpreting the experimental findings for the emission spectra of a lens-shaped In0.5Ga0.5As self-assembled quantum dot. Our theoretical predictions for the interlevel spacing as well as for the dephasing time caused by electron–longitudinal optical phonon interactions are in good agreement with the experimental results.

The rationale of this magnetoencephalographic (MEG) study was the quest for temporal aspects of the fMRI-characterized hemispheric asymmetries of auditory cortex functions during the processing of simple linearly frequency-modulated (FM) tones. We searched for parameters which distinguish a stimulus-related task condition—the categorical discrimination of direction (upward versus downward) of frequency modulation—from mere exposure to the same FM tones. We found that the M100-peak latency after FM tones was significantly shorter in the task condition than in the exposure condition, in the left but not in the right hemisphere.

Under an in-plane magnetic field, the density of states of quasi-two-dimensional carriers deviates from the occasionally stereotypic step-like form both quantitatively and qualitatively. Here we study how this affects the spin-subband populations and the spin-polarization as functions of the temperature, T, and the in-plane magnetic field, B, for narrow to wide dilute-magnetic-semiconductor quantum wells. We examine a wide range of material and structural parameters, focusing on the quantum well width, the magnitude of the spin-spin exchange interaction, and the sheet carrier concentration. Generally, increasing T, the carrier spin-splitting, Uoσ, decreases, augmenting the influence of the “minority”-spin carriers. Increasing B, Uoσ, increases and, accordingly, carriers populate “majority”-spin subbands while they abandon “minority”-spin subbands. Furthermore, in line with the density of states modification, all energetically higher subbands become gradually depopulated. We also indicate the ranges where the system is completely spin-polarized.

We examine a quantum dot (QD) illuminated in the near field with subwavelength spatial resolution, while simultaneously it is subjected to a magnetic field of variable orientation and magnitude. The magnetic field orientation can conserve or destroy the zero-magnetic-field ("structural") symmetry. The asymmetry induced by the magnetic field -except for specific orientations along symmetry axes- can be uncovered in the near-field (NF) but not in the far-field (FF) spectra. We predict that NF magnetoabsorption experiments of realistic spatial resolution could reveal the QD symmetry. This exceptional symmetry-resolving power of the near-field optics, is lost in the far field.