Press releases
Please quote Nature Physics as the source of these items.
The October 2007 issue of Nature Physics is available online.
October 2007
Count down, and up
Online this week in Nature Physics, Matthias Ediger and co-workers describe optical studies of quantum dots — semiconductor nanostructures that confine electrons or 'holes' — containing a record number of six electrons or holes.
Previous studies on dots with up to three electrons or one hole — a positive entity left when an electron is removed — have revealed profound changes due to interactions between the charged entities. For example, each added electron makes it harder for the next one to enter. This behaviour is expected. However, the behaviour of holes is unexpected. Instead of populating the available energy levels in the same way as electrons, that is, sequentially from the lowest to the highest, a hole can seem to skip a low energy state and instead occupy a higher one. The authors' explanation of this behaviour involves an additional interaction between the hole and the crystalline lattice of the dot — the spin-orbit effect. Holes therefore seem to be more complicated than electrons.
Quantum dots show promise for use in quantum information technology, but first we need to understand the basic science and control of the energy states. This new study takes an important step in this direction.
Peculiar many-body effects revealed in the spectroscopy of highly charged quantum dots
M. Ediger, G. Bester, A. Badolato, P. M. Petroff, K. Karrai, A. Zunger & R. J. Warburton
Published online: 14 October 2007 | doi 10.1038/nphys748