The expression for additional subgap current in the presence of electron-phonon interaction is derived. We show that the phonon assisted tunneling leads to appearance of peaks on current-voltage characteristics at the Josephson frequencies corresponding to the Raman-active phonons. The relation of the obtained results to experimental observations are discussed.Comment: 8 pages, submitted to PR

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.

The interaction between electrons and the vibrational degrees of freedom of a molecular quantum dot can lead to an exponential suppression of the conductance, an effect which is commonly termed Franck-Condon blockade. Here, we investigate this effect in a quantum dot driven by time-periodic gate voltages and tunneling amplitudes using nonequilibrium Green's functions and a Floquet expansion. Building on previous results showing that driving can lift the Franck-Condon blockade, we investigate driving protocols which can be used to pump charge across the quantum dot. In particular, we show that due to the strongly coupled nature of the system, the pump current at resonance is an exponential function of the drive strength.

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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.