98 research outputs found
Enhancement of parametric pumping due to Andreev reflection
We report properties of parametric electron pumping in the presence of a
superconducting lead. Due to a constructive interference between the direct
reflection and the multiple Andreev reflection, the pumped current is greatly
enhanced. For both quantum point contacts and double barrier structures at
resonance, we obtain exact solutions in the weak pumping regime showing that
, which should be compared with the result of conductance
. Numerical results are also provided for the strong pumping
regime showing interesting Andreev assisted pumping behaviour
Nonlinear I-V Characteristics of a Mesoscopic Conductor
We present a general theoretical formulation, based on nonequilibrium Green's
functions, for nonlinear DC transport in multi-probe mesoscopic conductors. The
theory is gauge invariant and is useful for the predictions of current-voltage
characteristics and the nonequilibrium charge pile-ups inside the conductor. We
have provided a detailed comparison between the gauge invariant scattering
matrix theory and our theory. We have also given several examples where the I-V
curve can be obtained analytically. The effects of exchange and correlation
have been considered explicitly
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