A quantum point contact is a narrow constriction between two wider electron reservoirs. With extensive numerical calculations we showed that an electronic state with a spin-1/2 magnetic moment forms in the contact under quite general conditions. In addition, we showed that such an impurity can also form at large magnetic fields, for a specific value of the field, and sometimes even at the opening of the second transverse mode in the contact. We found out that a magnetic impurity forms for a wide range of electron densities in the reservoirs.
COBISS.SI-ID: 20336679
Magnetic properties of doped superconductors show at low doping unusual scaling behaviour: for doping levels, which still support metallic behaviour, the local susceptibility depends predominantly on the ratio E/kBT, where E is the excitation energy and T the temperature. In our work we have presented a theory, whereby the scaling behaviour can be understood as a consequence of a few simple ingredients: a) the collective modes are strongly overdamped at low E, and b) there is no long-range order at low T.
COBISS.SI-ID: 1719652
Fidelity serves as a benchmark for the reliability in quantum information processes has recently attracted much interest as a measure of the susceptibility of dynamics to perturbations. A rich variety of regimes for fidelity decay have emerged. The main theoretical approach used in the review is using time correlation functions while Vanicek's uniform approach to semiclassics and random matrix theory provide important alternatives and show complementary aspects.
COBISS.SI-ID: 1972068
Fidelity serves as a benchmark for the reliability in quantum information processes has recently attracted much interest as a measure of the susceptibility of dynamics to perturbations. A rich variety of regimes for fidelity decay have emerged. The main theoretical approach used in the review is using time correlation functions while Vanicek's uniform approach to semiclassics and random matrix theory provide important alternatives and show complementary aspects.
COBISS.SI-ID: 20869415
Conducting nano-particle films are of great importance for the nanoelectronics, primarily because of single-electron-processes, which are made possible by nanosize of the capacitively coupled nanoparticles. In collaboration with the experimental group in Nottingham, we have studied the structure and conduction properties of the selfassembled films with gold nano-particles on a substrate. We have developed a numerical model for the current transport via single-electron tunneling through the junctions between nano-particles when the film is driven by the voltage difference.
COBISS.SI-ID: 20694311