We analyzed the localized charge dynamics in the system of interacting single-level quantum dots (QDs) coupled to the continuous spectrum states in the presence of Coulomb interaction between electrons within the dots. Different dots geometry and initial charge configurations were considered. The analysis was performed by means of Heisenberg equations for localized electrons pair correlators. We revealed that charge trapping takes place for a wide range of system parameters and we suggested the QDs geometry for experimental observations of this phenomenon. We demonstrated significant suppression of Coulomb correlations with the increasing of QDs number. We found the appearance of several time scales with the strongly different relaxation rates for a wide range of the Coulomb interaction values.
We analyze time evolution of the opposite spin electron occupation for the single Anderson impurity coupled to two reservoirs in the presence of applied bias voltage. We demonstrate that non-stationary spin-polarized currents are flowing in the both leads. We reveal that spin polarization and direction of the non-stationary currents in each lead can be simultaneously inverted by the sudden changing of the applied bias voltage.
We investigated the typical time scales of the Kondo correlations formation for the single-state Anderson model, when coupling to the reservoir is switched on at the initial time moment. The influence of the Kondo effect appearance on the system non-stationary characteristics was analyzed and discussed.
We analyzed theoretically localized charge relaxation in a double quantum dot (QD) system coupled with continuous spectrum states in the presence of localized electrons Coulomb interaction in a single QD. We have found that for a wide range of system parameters charge relaxation occurs through two stable regimes with significantly different relaxation rates. A peculiar time moment exists in the system at which rapid switching between stable regimes takes place. We consider this phenomenon to be applicable for creation of active elements in nano-electronics based on the fast transition effect between two stable states.
Idealized graphene monolayer is considered neglecting the van der Waals potential of the substrate and the role of the nonmagnetic impurities. The effect of the long-range Coulomb repulsion in an ensemble of Dirac fermions on the formation of the superconducting pairing in a monolayer is studied in the framework of the Kohn–Luttinger mechanism. The electronic structure of graphene is described in the strong coupling Wannier representation on the hexagonal lattice. We use the Shubin–Vonsowsky model which takes into account the intra- and intersite Coulomb repulsions of electrons. The Cooper instability is established by solving the Bethe–Salpeter integral equation, in which the role of the effective interaction is played by the renormalized scattering amplitude. The renormalized amplitude contains the Kohn–Luttinger polarization contributions up to and including the second-order terms in the Coulomb repulsion. We construct the superconductive phase diagram for the idealized graphene monolayer and show that the Kohn–Luttinger renormalizations and the intersite Coulomb repulsion significantly affect the interplay between the superconducting phases with f-,d+id-, and p+ip-wave symmetries of the order parameter.