Nonadiabatic electron charge pumping in coupled semiconductor quantum dots

Abstract

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.

Quenched dynamics of entangled states in correlated quantum dots

“…The first term in each right-hand part of Eqs. (13) [Γ · (n σ 21 +n σ 12 ) or Γ · (n σ 11 +n σ 22 )] appears due to the interference effects caused by the charge relaxation to reservoir through different possible channels, similar to the Fano effect. These terms are absent if only one quantum dot is coupled to reservoir.…”

Diagnostics of many-particle electronic states: Non-stationary currents and residual charge dynamics

“…Matrix element, which corresponds to transitions between this state and empty states is equal to zero. This transition is forbidden by the symmetry of the tunneling Hamiltonian (4). If there is the way of allowed transitions from initial state to the "dark state" during relaxation processes, the residual charge is trapped in this one-particle state.…”

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

“…By means of Heisenberg equations of motion one can get system of equations exactly taking into account correlations of electron filling numbers in localized states in all orders [27], [28] (for weak tunneling coupling to the leads). But it is rather tedious to restore the information about the definite charge and spin configurations with different number of electrons from all order correlators for initial levels occupation numbers.…”