Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 48: Superconductivity: Heterostructures, Andreev Scattering, Proximity Effect, Vortices
TT 48.11: Vortrag
Freitag, 30. März 2012, 12:15–12:30, H 2053
Driven superconducting proximity effect in interacting quantum dots — •Ali G. Moghaddam1, Michele Governale2, and Jürgen König1 — 1Theoretische Physik, Universität Duisburg-Essen and CeNIDE, 47048 Duisburg, Germany — 2School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand
We show that strong superconducting correlations can be induced in an interacting quantum dot (QD) using fast oscillations in the effective coupling between the dot and superconducting leads which drive the dot out of equilibrium. This is in contrast with the well-known equilibrium state suppression of proximity effect in interacting QDs. In fact although interaction prohibits the superposition of empty (0) and doubly-occupied (d) states, fast coherent dynamics accompanied by the fast variations in the tunnel coupling can produce a nonequilibrium finite probability for such a superposition. Subsequently the superconducting correlations are established inside the QD when the energy difference between 0 and d states coincide with the frequency of driving oscillations. Simultaneously the nonequilibrium occupation probabilities of 0 and d states cause a pumping current flowing to the normal lead connected to the dot. Finally we demonstrate coherent oscillations in both dot charge and current by applying a pulsed oscillatory field to the coupling of dot and superconductor which show the possibility of coherent manipulation in the subspace of 0 and d states by changing the pulse duration.