Eur. Phys. J. B 18, 311-318 (2000)
https://doi.org/10.1007/s100510070063

The different effect of electron-electron interaction on the spectrum of atoms and quantum dots^*

¹ Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
² Department of Physics and Solid State Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel

Received: 3 April 2000
Revised: 7 August 2000
Published online: 15 November 2000

Abstract

Though atoms and quantum dots typically contain a comparable number of electrons, the number of discrete levels resolved in spectroscopy experiments is very different for the two systems. In atoms, hundreds of levels are observed while in quantum dots that number is usually smaller than 10. In the present work, this difference is traced to the different confining potentials in these systems. In atoms, the soft confining potential leads to large spatial extent of the excited electron's wave function and hence to weak Coulomb interaction with the rest of the atomic electrons. The resulting level broadening is smaller than the single particle level spacing and decreases as the excitation energy is increased. In quantum dots, on the other hand, the sharp confining potential results in electron-electron scattering rates that grow rapidly with energy and fairly quickly exceed the approximately constant single particle level spacing. The number of discrete levels in quantum dots is hence limited by electron-electron interaction, whose effect is negligible in atoms.