Spin-polarized transport through a single-level quantum dot interacting with a local phonon mode is studied in the frame of the nonequilibrium Green-function technique. It is shown that strong electron–phonon interaction gives rise to a significant current suppression, to additional resonance peaks in the differential conductance as well as to oscillations of the tunnel magnetoresistance. Also,...

We investigate a system of three tunnel-coupled semiconductor quantum dots in a triangular geometry, one of which is connected to a metallic lead, in the regime where each dot is essentially singly occupied. Both ferromagnetic and antiferromagnetic spin2 Kondo regimes, separated by a quantum phase transition, are shown to arise on tuning the interdot tunnel couplings and should be accessible ex...

We study dc charge and spin transport through a weakly coupled quantum dot, driven by a nonadiabatic periodic change of system parameters. We generalize the model of Tien and Gordon to simultaneously oscillating voltages and tunnel couplings. When applying our general result to the two-parameter charge pumping in quantum dots, we find interference effects between the oscillations of the voltage...

We investigate the effect of local electron correlations on transport through parallel quantum dots. The linear conductance as a function of gate voltage is strongly affected by the interplay of the interaction U and quantum interference. We find a pair of novel correlation-induced resonances separated by an energy scale that depends exponentially on U. The effect is robust against a small detu...

We report on the realization of a single-electron source, where current is transported through a single-level quantum dot (Q) tunnel coupled to two superconducting leads (S). When driven with an ac gate voltage, the experiment demonstrates electron turnstile operation. Compared to the more conventional superconductor-normal-metal-superconductor turnstile, our superconductor-quantum-dot-supercon...

We calculate current, spin current and tunnel magnetoresistance (TMR) for a quantum dot coupled to ferromagnetic leads in the presence of a square wave of bias voltage. Our results are obtained via time-dependent nonequilibrium Green function. Both parallel and antiparallel lead magnetization alignments are considered. The main findings include a wave of spin accumulation and spin current that ...

We consider the continuous measurement of a double quantum dot by a weakly coupled detector ~tunnel point contact nearby!. While the conventional approach describes the gradual system decoherence due to the measurement, we study the situation when the detector output is explicitly recorded that leads to the opposite effect: gradual purification of the double-dot density matrix. The nonlinear La...

Systematic ensemble photoluminescence studies have been performed on type-I InP-quantum dots in Al0.20Ga0.80InP barriers, emitting at approximately 1.85 eV at 5 K. The influence of different barrier configurations as well as the incorporation of additional tunnel barriers on the optical properties has been investigated. The confinement energy between the dot barrier and the surrounding barrier ...

three different nanostructured semiconductor lasers were studied – the quantum dot passively mode-locked laser, the dual-mode quantum dot laser and the optically-injected quantum dot distributed feedback laser. The key milestones achieved were: 1) the use of optical feedback to reduce the timing jitter of the pulsed lasers from 295 fs/cycle to 32 fs/cycle, 2) experimental determination of the o...

We numerically calculated the full capacitance matrices for both one-dimensional (1D) and two-dimensional (2D) quantum-dot arrays. We found it is necessary to use the full capacitance matrix in modeling coupled quantum dot arrays due to weaker screening in these systems in comparison with arrays of normal metal tunnel junctions. The static soliton potential distributions in both 1D and 2D array...