Quantum physics in in quantum dots

27.4.2009: Prof. Dr. Klaus Ensslin (ETH-Zürich): Electrons in quantum dots are confined in all three spatial dimensions. In semiconduc-tors the confinement potential, the number of the electrons and the tunnel coupling of the quantum dot to the outside world can be tuned by gate electrodes. With suitable detec-tors it is possible to monitor the current through the quantum dot in a time-resolved fash-ion on the level of individual electrons allowing ultra-sensitive current and noise meas-urement. Similar to a double slit experiment in vacuum, the Aharonov-Bohm effect can be exploited in a ring geometry to measure the interference of individual electrons. For coupled quantum systems the question of back action and correlated detection can be investigated. While this development has lead to exquisite control of quantum systems in conventional semiconductors, quantum dots in graphene, a single layer of carbon atoms, hold the promise for ever smaller and better controlled quantum structures and longer coherence times.