Based on an analytical expression for the photoluminescence (PL) intensity of individual quantum dots (QDs) in the linear regime, we investigate its dependence upon the size of self‐assembled InGaAs QDs. We prove that decreasing the QD size, the PL‐emission spectrum moves to higher energy, due to the confinement‐induced blue‐shift of the electronic levels and the redshift from the increased Coulomb interaction caused by the compression of the exciton radii. This shift is in agreement with experimental results. Moreover, we show that larger dots provide more intense PL spectra.

We examined effects of the task of categorizing linear frequency-modulated (FM) sweeps into rising and falling on auditory evoked magnetic fields (AEFs) from the human auditory cortex, recorded by means of whole-head magnetoencephalography. AEFs in this task condition were compared with those in a passive condition where subjects had been asked to just passively listen to the same stimulus material. We found that the M100-peak latency was significantly shorter for the task condition than for the passive condition in the left but not in the right hemisphere. Furthermore, the M100-peak latency was significantly shorter in the right than in the left hemisphere for the passive and the task conditions. In contrast, the M100-peak amplitude did not differ significantly between conditions, nor between hemispheres. We also analyzed the activation strength derived from the integral of the absolute magnetic field over constant time windows between stimulus onset and 260 ms. We isolated an early, narrow time range between about 60 ms and 80 ms that showed larger values in the task condition, most prominently in the right hemisphere. These results add to other imaging and lesion studies which suggest a specific role of the right auditory cortex in identifying FM sweep direction and thus in categorizing FM sweeps into rising and falling.

Due to the competition between spatial and magnetic confinement, the density of states (DOS) of a quasi-two-dimensional system deviates from the ideal step-like form both quantitatively and qualitatively. 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 (QWs). We focus on the QW width, the magnitude of the spin–spin exchange interaction, and the sheet carrier concentration dependence. We look for ranges where the system is completely spin polarized. Increasing T, the carrier spin splitting, U0σU0σ">, decreases, while on increasing B, U0σ"> U0σ increases. Moreover, due to the DOS modification, all energetically higher subbands become gradually depopulated.

We investigate the emission spectra of individual lens-shaped self-assembled quantum dots (QDs) in the high-temperature regime in order to contribute to the fine structural analysis and to the appreciation of the QDs’ optical response. Our theoretical analysis results in an expression for the photoluminescence (PL) intensity of QDs in the linear regime, which reproduces satisfactorily the experimentally observed PL signal of individual lens-shaped In0.5Ga0.5As self-assembled QDs. Using the appropriate material parameters, the 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 experiment.

We study theoretically the potential for control of the electron population in a single GaAs/AlGaAs quantum well that is coupled by strong pulsed electromagnetic fields. Using numerical calculations we present the conditions that lead to high-efficiency intersubband population inversion.