29 research outputs found
Charge on the quantum dot in the presence of tunneling current
The calculation of the charge present in central region of the double barrier
structure at non-equilibrium conditions is discussed. We propose here a simple
method to calculate non equilibrium Green's functions which allows consistent
calculations of retarded and distribution functions. To illustrate the approach
we calculate the charge on the quantum dot coupled {\it via} tunnel barriers to
two external leads having different chemical potentials and .
The obtained results have been compared with other approaches existing in the
literature. They all agree in the equilibrium situation and the departures grow
with increasing the difference .Comment: 9 pages, 2 (.eps) figures, to be published in Solid State Commu
Non-equilibrium Kondo effect in asymmetrically coupled quantum dot
The quantum dot asymmetrically coupled to the external leads has been
analysed theoretically by means of the equation of motion (EOM) technique and
the non-crossing approximation (NCA). The system has been described by the
single impurity Anderson model. To calculate the conductance across the device
the non-equilibrium Green's function technique has been used. The obtained
results show the importance of the asymmetry of the coupling for the appearance
of the Kondo peak at nonzero voltages and qualitatively explain recent
experiments.Comment: 7 pages, 6 figures, Physical Review B (accepted for publication
Electron transport through strongly interacting quantum dot coupled to normal metal and superconductor
We study the electron transport through the quantum dot coupled to the normal
metal and BCS-like superconductor (N - QD - S) in the presence of the Kondo
effect and Andreev scattering. The system is described by the single impurity
Anderson model in the limit of strong on-dot interaction. We use recently
proposed equation of motion technique for Keldysh nonequilibrium Green's
function together with the modified slave boson approach to study the electron
transport. We derive formula for the current which contains various tunneling
processes and apply it to study the transport through the system. We find that
the Andreev conductance is strongly suppressed and there is no zero-bias
(Kondo) anomaly in the differential conductance. We discuss effects of the
particle-hole asymmetry in the electrodes as well as the asymmetry in the
couplings.Comment: Supercond. Sci. Technol. - accepted for publicatio