We introduce an all-electrical measurement technique, which makes it possible to prepare and detect the ground and excited many-particle states in self-assembled InAs QDs at 4K. This way, the pure-electron spectra of QD-hydrogen, -helium and -lithium
are resolved. Comparison with detailed many-body calculations enables us to identify the different charge configurations and in particular detect the singlet and triplet spin states of QD helium. Furthermore, the time-resolved evolution of the density of states from non-equilibrium to equilibrium charge occupation is shown.
We experimentally investigate interference effects in transport across a single incompressible strip at the edge of the quantum Hall system by using a Fabry-Perot type interferometer. We find the interference oscillations in transport across the inco
mpressible strips with local filling factors $ u_c=1, 4/3, 2/3$ even at high imbalances, exceeding the spectral gaps. In contrast, there is no sign of the interference in transport across the principal Laughlin $ u_c=1/3$ incompressible strip. This indicates, that even at fractional $ u_c$, the interference effects are caused by normal electrons. The oscillations period is determined by the effective interferometer area, which is sensitive to the filling factors because of screening effects.
