P.I. Arseyev

Phonon assisted tunneling in Josephson junctions

Abstract The expression for additional subgap current in the presence of electron–phonon interaction is derived. We show that the phonon assisted tunneling leads to the appearance of peaks on current-voltage characteristics at the Josephson frequencies corresponding to the Raman-active phonons. The relation of the obtained results to the experimental observation are discussed.

Localized charge bifurcation in the coupled quantum dots

Abstract We theoretically analyzed localized charge relaxation in a double quantum dot (QD) system coupled with continuous spectrum states in the presence of Coulomb interaction between electrons within a dot. We have found that for a wide range of the system parameters charge relaxation occurs through two stable regimes with significantly different relaxation rates. A certain instant of time exists in the system at which rapid switching between stable regimes takes place. We consider this phenomenon to be applicable for the creation of active elements in nano-electronics based on the fast transition effect between two stable states.

Charge and spin configurations in the coupled quantum dots with Coulomb correlations induced by tunneling current

We investigated the peculiarities of non-equilibrium charge states and spin configurations in the system of two strongly coupled quantum dots (QDs) weakly connected to the electrodes in the presence of Coulomb correlations. We analyzed the modification of non-equilibrium charge states and different spin configurations of the system in a wide range of applied bias voltage and revealed well pronounced ranges of system parameters where negative tunneling conductivity appears due to the Coulomb correlations.

Coulomb correlations effects on localized charge relaxation in the coupled quantum dots

We analyzed localized charge time evolution in the system of two interacting quantum dots (QD) (artificial molecule) coupled with the continuous spectrum states. We demonstrated that Coulomb interaction modifies relaxation rates and is responsible for non-monotonic time evolution of the localized charge. We suggested new mechanism of this non-monotonic charge time evolution connected with charge redistribution between different relaxation channels in each QD.

Tunneling transport through multi-electrons states in coupled quantum dots with Coulomb correlations

Abstract We investigated the peculiarities of non-equilibrium charge configurations in the system of two strongly coupled quantum dots (QDs) weakly connected to the reservoirs in the presence of Coulomb correlations. We revealed that total electron occupation demonstrates in some cases significant decreasing with increasing of applied bias – contrary to the situation when Coulomb correlations are absent and found well pronounced ranges of system parameters where negative tunneling conductivity appears due to the Coulomb correlations.

Charge trapping in the system of interacting quantum dots

Abstract We analyzed the localized charge dynamics in the system of N 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 electron 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 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.

Non-stationary spin-filtering effects in correlated quantum dot

Abstract The influence of external magnetic field switching “on” and “off” on the non-stationary spin-polarized currents in the system of correlated single-level quantum dot coupled to non-magnetic electronic reservoirs has been analyzed. It was shown that considered system can be used for the effective spin filtering by analyzing its non-stationary characteristics in particular range of applied bias voltage.

Time evolution of an entangled initial state in coupled quantum dots with Coulomb correlations

We proved that for arbitrary mixed state the concurrence and the entanglement are determined by the average value of electron’s pair correlation functions particular combinations. We analyzed the dynamics of the initial two-electronic state in two interacting single-level quantum dots (QDs) with Coulomb correlations, weakly tunnel coupled with an electronic reservoir. We obtained correlation functions of all orders for electrons in the QDs by decoupling high-order correlations between localized and band electrons in the reservoir. Analysis of the pair correlation functions time evolution allows to follow the changes of the concurrence and the entanglement during the relaxation and transient processes. We investigated dependence of the concurrence on the value of Coulomb interaction and energy levels spacing and found its monotonic behavior. The most interesting physical effect is that more entangled state than the initial one can be formed during the charge relaxation due to the Coulomb correlations. We also demonstrated that behavior of the two-electronic entangled state pair correlation functions in coupled QDs points to the fulfillment of the Hund’s rule for the strong Coulomb interaction. We revealed the appearance of dynamical inverse occupation of the QDs energy levels during the relaxation processes. Our results open up further perspectives in solid state quantum information based on the controllable dynamics of the entangled electronic states.

Non-stationary spin-polarized tunneling currents tuning by means of applied bias changing

We study time evolution of the opposite spin electron occupation numbers for the single Anderson impurity localized between two macroscopic leads in the presence of applied bias voltage. It was shown that non-stationary spin-polarized currents are present in the both leads and their polarization and direction in each lead can be controlled by the the applied bias voltage changing.

Two-level quantum dot susceptibility and polarization in the presence of Coulomb correlations

Susceptibility and polarization of two-level quantum dot (QD) with Coulomb correlations between localized electrons weakly connected to the reservoirs were carefully analyzed. It was revealed that both susceptibility and polarization depend strongly on high-order correlation functions of localized in QD electrons. It was demonstrated that susceptibility and polarization can be controlled by changing of applied bias voltage value, Coulomb correlations strength and Rabi frequency.