Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 8: Posters Transport

TT 8.15: Poster

Freitag, 4. März 2005, 14:00–18:00, Poster TU C

Cotunneling and coherent tunneling through quantum dots — •Bernhard Wunsch, Michael Tews, and Daniela Pfannkuche — 1. Institut für Theoretische Physik, Universität Hamburg

We study transport through a quantum dot coupled to two electronic reservoirs. Including all transport processes up to fourth order in tunneling [1] we go systematically beyond a master equation approach with transition rates obtained from Fermi’s Golden rule. Thus we are able to describe transport structures within the coulomb blockade regime due to cotunneling which allow to measure the excitation spectrum of the dot. In particular we identify peaks in the differential conductance inside the coulomb blockade which are due to a sequential tunneling process out of an excited state allowed by a previous inelastic cotunneling event[1]. Furthermore we investigate the effect of coherent tunneling, where different transport channels may interfere with each other and the quantum dot may be in a superposition of eigenstates [3].

[1] J. König, J. Schmid, H. Schoeller, and G. Schön, Phys. Rev. B 54 16820 (1996)

[2] M. Tews, Annalen der Physik 13 249-304 (2004)

[3] D. Boese, W. Hofstetter, and H. Schoeller, Phys. Rev. B 66 125315 (2002)