Europhys. Lett.
Volume 68, Number 5, December 2004
Page(s) 699 - 705
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 03 November 2004
Europhys. Lett., 68 (5), pp. 699-705 (2004)
DOI: 10.1209/epl/i2004-10258-6

Discrete charging of a quantum dot strongly coupled to external leads

R. Berkovits1, F. von Oppen2 and J. W. Kantelhardt3

1  The Minerva Center, Department of Physics, Bar-Ilan University Ramat-Gan 52900, Israel
2  Institut für Theoretische Physik, Freie Universität Berlin Arnimallee 14, 14195 Berlin, Germany
3  Institut für Theoretische Physik III, Justus-Liebig-Universität Giessen 35392 Giessen, Germany

received 19 May 2004; accepted 30 September 2004
published online 3 November 2004

We examine a quantum dot with $N_{\ab{dot}}$ levels which is strongly coupled to leads for varying number of channels N in the leads. It is shown both analytically and numerically that for strong couplings between the dot and the leads, at least $N_{\ab{dot}}-N$ bound states (akin to subradiant states in optics) remain on the dot. These bound states exhibit discrete charging and, for a significant range of charging energies, strong Coulomb blockade behavior as a function of the chemical potential. The physics changes for large charging energy, where the same (superradiant) state is repeatedly charged.

73.23.Hk - Coulomb blockade; single-electron tunneling.
71.15.Dx - Computational methodology (Brillouin zone sampling, iterative diagonalization, pseudopotential construction).
73.23.-b - Electronic transport in mesoscopic systems.

© EDP Sciences 2004