CeNS Colloquium

Prof. Axel Lorke, Faculty of Physics and CENIDE, University of Duisburg-Essen

Quantum dots are small semiconductor structures, - small enough so thatelectrons inside them will be confined to their quantum mechanical groundstates. They have long been ideal model systems to study the dynamics of singleelectrons and their interaction with other charge carriers. As such, they haveoften been labeled “artificial atoms”, and many of the phenomena, known fromatomic and molecular physics have been replicated in quantum dots - however,on a completely different length scale and with the tunability that semiconductornanotechnology offers. In the past, the approaches to study quantum dots werelargely separated into two separate fields, namely optical and transportspectroscopy.In this talk, the atom-like structure and basic quantum properties of selfassembledquantum dots will reviewed. Recent developments will be presentedthat make it possible to investigate the non-equilibrium dynamics of carriers,injected into excited electronic states. Making use of a combination of optical andtransport spectroscopy, it will be shown how it is possible to “watch” (by opticalmeans) individual quantum events of single electrons, tunneling into and out of aquantum dot. The resulting random telegraph signal can be statisticallyevaluated to reveal both equilibrium and non-equilibrium properties.